OncoSimulR: genetic simulation with arbitrary epistasis and mutator genes in asexual populations.

PubMed

Diaz-Uriarte, Ramon

2017-06-15

OncoSimulR implements forward-time genetic simulations of biallelic loci in asexual populations with special focus on cancer progression. Fitness can be defined as an arbitrary function of genetic interactions between multiple genes or modules of genes, including epistasis, restrictions in the order of accumulation of mutations, and order effects. Mutation rates can differ among genes, and can be affected by (anti)mutator genes. Also available are sampling from simulations (including single-cell sampling), plotting the genealogical relationships of clones and generating and plotting fitness landscapes. Implemented in R and C ++, freely available from BioConductor for Linux, Mac and Windows under the GNU GPL license. Version 2.5.9 or higher available from: http://www.bioconductor.org/packages/devel/bioc/html/OncoSimulR.html . GitHub repository at: https://github.com/rdiaz02/OncoSimul. ramon.diaz@iib.uam.es. Supplementary data are available at Bioinformatics online. © The Author 2017. Published by Oxford University Press.

The effect of newly induced mutations on the fitness of genotypes and populations of yeast (Saccharomyces cerevisiae).

PubMed

Orthen, E; Lange, P; Wöhrmann, K

1984-12-01

This paper analyses the fate of artificially induced mutations and their importance to the fitness of populations of the yeast, Saccharomyces cerevisiae, an increasingly important model organism in population genetics. Diploid strains, treated with UV and EMS, were cultured asexually for approximately 540 generations and under conditions where the asexual growth was interrupted by a sexual phase. Growth rates of 100 randomly sampled diploid clones were estimated at the beginning and at the end of the experiment. After the induction of sporulation the growth rates of 100 randomly sampled spores were measured. UV and EMS treatment decreases the average growth rate of the clones significantly but increases the variability in comparison to the untreated control. After selection over approximately 540 generations, variability in growth rates was reduced to that of the untreated control. No increase in mean population fitness was observed. However, the results show that after selection there still exists a large amount of hidden genetic variability in the populations which is revealed when the clones are cultivated in environments other than those in which selection took place. A sexual phase increased the reduction of the induced variability.

Genetic analysis of the roles of agaA, agaI, and agaS genes in the N-acetyl-D-galactosamine and D-galactosamine catabolic pathways in Escherichia coli strains O157:H7 and C

PubMed Central

2013-01-01

Background The catabolic pathways of N-acetyl-D-galactosamine (Aga) and D-galactosamine (Gam) in E. coli were proposed from bioinformatic analysis of the aga/gam regulon in E. coli K-12 and later from studies using E. coli C. Of the thirteen genes in this cluster, the roles of agaA, agaI, and agaS predicted to code for Aga-6-P-deacetylase, Gam-6-P deaminase/isomerase, and ketose-aldolase isomerase, respectively, have not been experimentally tested. Here we study their roles in Aga and Gam utilization in E. coli O157:H7 and in E. coli C. Results Knockout mutants in agaA, agaI, and agaS were constructed to test their roles in Aga and Gam utilization. Knockout mutants in the N-acetylglucosamine (GlcNAc) pathway genes nagA and nagB coding for GlcNAc-6-P deacetylase and glucosamine-6-P deaminase/isomerase, respectively, and double knockout mutants ΔagaA ΔnagA and ∆agaI ∆nagB were also constructed to investigate if there is any interplay of these enzymes between the Aga/Gam and the GlcNAc pathways. It is shown that Aga utilization was unaffected in ΔagaA mutants but ΔagaA ΔnagA mutants were blocked in Aga and GlcNAc utilization. E. coli C ΔnagA could not grow on GlcNAc but could grow when the aga/gam regulon was constitutively expressed. Complementation of ΔagaA ΔnagA mutants with either agaA or nagA resulted in growth on both Aga and GlcNAc. It was also found that ΔagaI, ΔnagB, and ∆agaI ΔnagB mutants were unaffected in utilization of Aga and Gam. Importantly, ΔagaS mutants were blocked in Aga and Gam utilization. Expression analysis of relevant genes in these strains with different genetic backgrounds by real time RT-PCR supported these observations. Conclusions Aga utilization was not affected in ΔagaA mutants because nagA was expressed and substituted for agaA. Complementation of ΔagaA ΔnagA mutants with either agaA or nagA also showed that both agaA and nagA can substitute for each other. The ∆agaI, ∆nagB, and ∆agaI ∆nagB mutants were not affected in Aga and Gam utilization indicating that neither agaI nor nagB is involved in the deamination and isomerization of Gam-6-P. We propose that agaS codes for Gam-6-P deaminase/isomerase in the Aga/Gam pathway. PMID:23634833

Pre-exposure to simultaneous, but not individual, climate change stressors limits acclimation capacity of Irukandji jellyfish polyps to predicted climate scenarios

NASA Astrophysics Data System (ADS)

Klein, Shannon G.; Pitt, Kylie A.; Carroll, Anthony R.

2017-09-01

Researchers have investigated the immediate effects of end-of-century climate change scenarios on many marine species, yet it remains unclear whether we can reliably predict how marine species may respond to future conditions because biota may become either more or less resistant over time. Here, we examined the role of pre-exposure to elevated temperature and reduced pH in mitigating the potential negative effects of future ocean conditions on polyps of a dangerous Irukandji jellyfish Alatina alata. We pre-exposed polyps to elevated temperature (28 °C) and reduced pH (7.6), in a full factorial experiment that ran for 14 d. We secondarily exposed original polyps and their daughter polyps to either current (pH 8.0, 25 °C) or future conditions (pH 7.6, 28 °C) for a further 34 d to assess potential phenotypic plastic responses and whether asexual offspring could benefit from parental pre-exposure. Polyp fitness was characterised as asexual reproduction, respiration, feeding, and protein concentrations. Pre-exposure to elevated temperature alone partially mitigated the negative effects of future conditions on polyp fitness, while pre-exposure to reduced pH in isolation completely mitigated the negative effects of future conditions on polyp fitness. Pre-exposure to the dual stressors, however, reduced fitness under future conditions relative to those in the control treatment. Under future conditions, polyps had higher respiration rates regardless of the conditions they were pre-exposed to, suggesting that metabolic rates will be higher under future conditions. Parent and daughter polyps responded similarly to the various treatments tested, demonstrating that parental pre-exposure did not confer any benefit to asexual offspring under future conditions. Importantly, we demonstrate that while pre-exposure to the stressors individually may allow Irukandji polyps to acclimate over short timescales, the stressors are unlikely to occur in isolation in the long term, and thus, warming and acidification in parallel may prevent polyp populations from acclimating to future ocean conditions.

The effects of outbreeding on a parasitoid wasp fixed for infection with a parthenogenesis-inducing Wolbachia symbiont.

PubMed

Lindsey, A R I; Stouthamer, R

2017-12-01

Trichogramma wasps can be rendered asexual by infection with the maternally inherited symbiont Wolbachia. Previous studies indicate the Wolbachia strains infecting Trichogramma wasps are host-specific, inferred by failed horizontal transfer of Wolbachia to novel Trichogramma hosts. Additionally, Trichogramma can become dependent upon their Wolbachia infection for the production of female offspring, leaving them irreversibly asexual, further linking host and symbiont. We hypothesized Wolbachia strains infecting irreversibly asexual, resistant to horizontal transfer Trichogramma would show adaptation to a particular host genetic background. To test this, we mated Wolbachia-dependent females with males from a Wolbachia-naïve population to create heterozygous wasps. We measured sex ratios and fecundity, a proxy for Wolbachia fitness, produced by heterozygous wasps, and by their recombinant offspring. We find a heterozygote advantage, resulting in higher fitness for Wolbachia, as wasps will produce more offspring without any reduction in the proportion of females. While recombinant wasps did not differ in total fecundity after 10 days, recombinants produced fewer offspring early on, leading to an increased female-biased sex ratio for the whole brood. Despite the previously identified barriers to horizontal transfer of Wolbachia to and from Trichogramma pretiosum, there were no apparent barriers for Wolbachia to induce parthenogenesis in these non-native backgrounds. This is likely due to the route of infection being introgression rather than horizontal transfer, and possibly the co-evolution of Wolbachia with the mitochondria rather than the nuclear genome. These results help to elucidate the mechanisms by which Wolbachia adapt to hosts and the evolution of host-symbiont phenotypes.

Genetic architecture and the evolution of sex.

PubMed

Lohaus, Rolf; Burch, Christina L; Azevedo, Ricardo B R

2010-01-01

Theoretical investigations of the advantages of sex have tended to treat the genetic architecture of organisms as static and have not considered that genetic architecture might coevolve with reproductive mode. As a result, some potential advantages of sex may have been missed. Using a gene network model, we recently showed that recombination imposes selection for robustness to mutation and that negative epistasis can evolve as a by-product of this selection. These results motivated a detailed exploration of the mutational deterministic hypothesis, a hypothesis in which the advantage of sex depends critically on epistasis. We found that sexual populations do evolve higher mean fitness and lower genetic load than asexual populations at equilibrium, and, under moderate stabilizing selection and large population size, these equilibrium sexual populations resist invasion by asexuals. However, we found no evidence that these long- and short-term advantages to sex were explained by the negative epistasis that evolved in our experiments. The long-term advantage of sex was that sexual populations evolved a lower deleterious mutation rate, but this property was not sufficient to account for the ability of sexual populations to resist invasion by asexuals. The ability to resist asexual invasion was acquired simultaneously with an increase in recombinational robustness that minimized the cost of sex. These observations provide the first direct evidence that sexual reproduction does indeed select for conditions that favor its own maintenance. Furthermore, our results highlight the importance of considering a dynamic view of the genetic architecture to understand the evolution of sex and recombination.

Patterns of Asexuality in China: Sexual Activity, Sexual and Romantic Attraction, and Sexual Desire.

PubMed

Zheng, Lijun; Su, Yanchen

2018-05-01

This study examined patterns of asexuality in Chinese asexual people in terms of sexual activities, sexual/romantic attraction, and sexual desire. The sample included 227 (64 men and 163 women) asexual participants and 57 (26 men and 31 women) uncertain asexual participants recruited from social networks for asexual people. The control group included 217 (115 men and 102 women) heterosexual participants recruited from general social networks. Participants scoring 40 or higher on the Asexuality Identification Scale were classified as asexual. Asexual participants reported having less frequent masturbation, sexual intercourse experience, and sexual and romantic attraction compared to heterosexual participants. Lower sexual attraction among asexuals indicated that "people who experience little or no sexual attraction" would be a more appropriate definition of asexuality. The pattern of uncertain asexual participants' sexual/romantic attraction and sexual desire was intermediate between heterosexual and asexual participants. Asexual participants scored significantly lower on dyadic sexual desire and slightly lower on solitary sexual desire than heterosexual participants. There were significant differences in sexual activities and solitary sexual desire among romantic orientation categories. Homoromantic participants showed higher dyadic sexual desire and were more likely to engage in masturbation, indicating the heterogeneity among asexual people. The findings indicated that Chinese asexual people showed similar patterns of asexuality as in Western nations. Specifically, asexual people have little or no sexual attraction, non-partner-orientated sexual desire, and are heterogeneous in sexual activities and sexual desire. This implies similar mechanisms underlying the etiology of asexuality across cultures.

Appropriate for gestational age (AGA)

MedlinePlus

Fetal age; Gestation; Development - AGA; Growth - AGA; Neonatal care - AGA; Newborn care - AGA ... Gestational age is the common term used during pregnancy to describe how far along the pregnancy is. It is ...

Androgenetic alopecia in men aged 40-69 years: prevalence and risk factors.

PubMed

Severi, G; Sinclair, R; Hopper, J L; English, D R; McCredie, M R E; Boyle, P; Giles, G G

2003-12-01

The epidemiology of androgenetic alopecia (AGA) is not fully understood. Although a strong genetic basis has long been identified, little is known of its non-genetic causes. To estimate the prevalence of and to determine risk factors for AGA in men aged 40-69 years in Australia. Men (n = 1390) were recruited at random from the electoral rolls to serve as controls in a population-based case-control study of prostate cancer. All were interviewed in person and direct observations of AGA were made. Men were grouped into the following categories; no AGA, frontal AGA, vertex AGA and full AGA (frontal and vertex AGA). Epidemiological data collected from these men were used for an analysis of risk factors for each AGA category using unconditional logistic regression with AGA category as the response variable adjusting for age, education and country of birth. The prevalence of vertex and full AGA increased with age from 31% (age 40-55 years) to 53% (age 65-69 years). Conversely, the proportion of men with only frontal AGA was very similar across all age groups (31-33%). No associations were found between pubertal growth spurt or acne, reports of adult body size at time of interview, urinary symptom score, marital status, or current smoking status or duration of smoking and the risk of any form of AGA. The consumption of alcohol was associated with a significant increase in risk of frontal and vertex AGA but not full AGA. Men with vertex AGA had fewer female sexual partners but average ejaculatory frequency did not differ between men in different AGA categories. Reported weight and lean body mass at reaching maturity at about 21 years of age were negatively associated with vertex balding (P for trend < 0.05) but not with frontal AGA or full AGA. Evidence for environmental influences on AGA remains very slight. Our study failed to confirm previously reported or hypothesized associations with smoking and benign prostatic hypertrophy. The associations that we found with alcohol consumption and with lean body mass at age 21 years would be worthy of further research if they were able to be replicated in other studies.

Occurrence of Parthenogenesis in Potato Tuber Moth

PubMed Central

Liu, Yan; Hu, Chun-Hua; Wang, Chun-Ya; Xiong, Yan; Li, Zong-Kai; Xiao, Chun

2018-01-01

Abstract Parthenogenesis, a natural form of asexual reproduction produced from unfertilized eggs, occurs in many insects in Hemiptera and Hymenoptera, but very rarely in Lepidoptera. The current study aimed to test the larval density dependent occurrence of parthenogenesis in potato tuber moth, Phthorimaea operculella (Zeller; Lepidoptera: Gelechiidae) under laboratory conditions. More than 10% of females out of 25 tested females that developed from the high larval density treatment at 45 larvae per tuber were capable to reproduce asexually. Both male and female offspring were produced parthenogenetically. The sexually reproductive offspring of a laboratory parthenogenetic population had a lower egg hatch rate, shorter larval stage, and shorter male life span when compared with the non-parthenogenetic population. This suggests that the sexually reproductive offspring of parthenogenetic population have a decreased overall fitness compared to the sexually reproductive offspring of non-parthenogenetic population.

Coming to an Asexual Identity: Negotiating Identity, Negotiating Desire.

PubMed

Scherrer, Kristin S

2008-10-01

Sexuality is generally considered an important aspect of self-hood. Therefore, individuals who do not experience sexual attraction, and embrace an asexual identity are in a unique position to inform the social construction of sexuality. This study explores the experiences of asexual individuals utilizing open ended Internet survey data from 102 self-identified asexual people. In this paper I describe several distinct aspects of asexual identities: the meanings of sexual, and therefore, asexual behaviors, essentialist characterizations of asexuality, and lastly, interest in romance as a distinct dimension of sexuality. These findings have implications not only for asexual identities, but also for the connections of asexuality with other marginalized sexualities.

Genomic and Proteomic Analyses of the Agarolytic System Expressed by Saccharophagus degradans 2-40†

PubMed Central

Ekborg, Nathan A.; Taylor, Larry E.; Longmire, Atkinson G.; Henrissat, Bernard; Weiner, Ronald M.; Hutcheson, Steven W.

2006-01-01

Saccharophagus degradans 2-40 (formerly Microbulbifer degradans 2-40) is a marine gamma-subgroup proteobacterium capable of degrading many complex polysaccharides, such as agar. While several agarolytic systems have been characterized biochemically, the genetics of agarolytic systems have been only partially determined. By use of genomic, proteomic, and genetic approaches, the components of the S. degradans 2-40 agarolytic system were identified. Five agarases were identified in the S. degradans 2-40 genome. Aga50A and Aga50D include GH50 domains. Aga86C and Aga86E contain GH86 domains, whereas Aga16B carries a GH16 domain. Novel family 6 carbohydrate binding modules (CBM6) were identified in Aga16B and Aga86E. Aga86C has an amino-terminal acylation site, suggesting that it is surface associated. Aga16B, Aga86C, and Aga86E were detected by mass spectrometry in agarolytic fractions obtained from culture filtrates of agar-grown cells. Deletion analysis revealed that aga50A and aga86E were essential for the metabolism of agarose. Aga16B was shown to endolytically degrade agarose to release neoagarotetraose, similarly to a β-agarase I, whereas Aga86E was demonstrated to exolytically degrade agarose to form neoagarobiose. The agarolytic system of S. degradans 2-40 is thus predicted to be composed of a secreted endo-acting GH16-dependent depolymerase, a surface-associated GH50-dependent depolymerase, an exo-acting GH86-dependent agarase, and an α-neoagarobiose hydrolase to release galactose from agarose. PMID:16672483

Understanding asexual identity as a means to facilitate culturally competent care: A systematic literature review.

PubMed

Jones, Catriona; Hayter, Mark; Jomeen, Julie

2017-12-01

To provide a contemporary overview of asexuality and the implications this has for healthcare practice. Individuals belonging to sexual minority groups face many barriers in accessing appropriate health care. The term "sexual minority group" is usually used to refer to lesbian women, gay, bisexual and transgender individuals. Anecdotal and research evidence suggests that those who identify as asexual have similar poor experiences. Systematic review and qualitative analysis. This work uses a systematic review and qualitative analysis of the existing interview data from self-identified asexuals, to construct features of the asexual identity. The findings will help practitioners and health professionals develop an understanding of this poorly understood construct. Ultimately this work is aimed at facilitating culturally competent care in the context of asexuality. Qualitative analysis produced three themes, which can be used, not only to frame asexuality in a positive and normalising way, but also to provide greater understanding of asexuality, "romantic differences coupled with sexual indifference," "validation through engagement with asexual communities" and "a diversity of subasexual identities." Having some understanding of what it means to identify as asexual, and respecting the choices made by asexuals can markedly improve the experiences of those who embrace an asexual identity when engaging with health care. Anecdotal evidence, taken from one of the largest asexual online forums, suggests that a number of self-identified asexuals choose not to disclose their identity to healthcare professionals through fear of their asexual status being pathologised, problematised or judged. Given that asexuality is a poorly understood concept, this may be due to lack of understanding on behalf of healthcare providers. The review provides health professionals and practitioners working in clinical settings with some insights of the features of an asexual identity to facilitate culturally competent care. © 2017 John Wiley & Sons Ltd.

A Qualitative Exploration of the "Coming Out" Process for Asexual Individuals.

PubMed

Robbins, Nicolette K; Low, Kathryn Graff; Query, Anna N

2016-04-01

"Coming out" is an important process not only for identity formation in sexual minorities, but also for increasing access to romantic partners of similar identities (Vaughan & Waehler, 2010). It is unclear how asexuality and the variations within the asexual community are revealed and communicated in the coming out process. Some asexual individuals may find no practical value in coming out, as they do not seek romantic partnerships, while others pursue romantic relationships that are devoid of sexual activity. To date, virtually no psychological research has explored the "coming out" experience for those with an asexual identity. The current research analyzed the "coming out" narratives of 169 self-identified asexual individuals recruited from three online asexual communities using a phenomenological approach. Salient themes were extracted from narratives about the experience of developing an asexual identity. Themes included skepticism from family and friends, lack of acceptance and misunderstanding, non-disclosure of the asexual identity, relief upon discovering the asexual community, and the role of the internet in asexual identity discovery and expression. A theoretical model of asexual identity development is proposed based on these findings.

Biochemical characterization and comparison of aspartylglucosaminidases secreted in venom of the parasitoid wasps Asobara tabida and Leptopilina heterotoma

PubMed Central

Coulette, Quentin; Lemauf, Séverine; Colinet, Dominique; Prévost, Geneviève; Anselme, Caroline; Poirié, Marylène

2017-01-01

Aspartylglucosaminidase (AGA) is a low-abundance intracellular enzyme that plays a key role in the last stage of glycoproteins degradation, and whose deficiency leads to human aspartylglucosaminuria, a lysosomal storage disease. Surprisingly, high amounts of AGA-like proteins are secreted in the venom of two phylogenetically distant hymenopteran parasitoid wasp species, Asobara tabida (Braconidae) and Leptopilina heterotoma (Cynipidae). These venom AGAs have a similar domain organization as mammalian AGAs. They share with them key residues for autocatalysis and activity, and the mature α- and β-subunits also form an (αβ)2 structure in solution. Interestingly, only one of these AGAs subunits (α for AtAGA and β for LhAGA) is glycosylated instead of the two subunits for lysosomal human AGA (hAGA), and these glycosylations are partially resistant to PGNase F treatment. The two venom AGAs are secreted as fully activated enzymes, they have a similar aspartylglucosaminidase activity and are both also efficient asparaginases. Once AGAs are injected into the larvae of the Drosophila melanogaster host, the asparaginase activity may play a role in modulating their physiology. Altogether, our data provide new elements for a better understanding of the secretion and the role of venom AGAs as virulence factors in the parasitoid wasps’ success. PMID:28742131

Crystallization and preliminary X-ray diffraction studies of two thermostable α-galactosidases from glycoside hydrolase family 36

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foucault, M.; Watzlawick, H.; Mattes, R.

2006-02-01

The α-galactosidases AgaA, AgaB and AgaA A355E mutant from Geobacillus stearothermophilus have been overexpressed in Escherichia coli. Crystals of AgaB and AgaA A355E have been obtained by the vapour-diffusion method and synchrotron data have been collected to 2.0 and 2.8 Å resolution, respectively. α-Galactosidases from thermophilic organisms have gained interest owing to their applications in the sugar industry. The α-galactosidases AgaA, AgaB and AgaA A355E mutant from Geobacillus stearothermophilus have been overexpressed in Escherichia coli. Crystals of AgaB and AgaA A355E have been obtained by the vapour-diffusion method and synchrotron data have been collected to 2.0 and 2.8 Å resolution,more » respectively. Crystals of AgaB belong to space group I222 or I2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 87.5, b = 113.3, c = 161.6 Å. Crystals of AgaA A355E belong to space group P3{sub 1}21 or P3{sub 2}21, with unit-cell parameters a = b = 150.1, c = 233.2 Å.« less

Contribution of hair density and hair diameter to the appearance and progression of androgenetic alopecia in Japanese men.

PubMed

Ishino, A; Takahashi, T; Suzuki, J; Nakazawa, Y; Iwabuchi, T; Tajima, M

2014-11-01

Androgenetic alopecia (AGA) is the most common type of baldness in men. The balding process is associated with the gradual miniaturization of hair follicles and successive hair loss. However, the relative contributions of hair density and diameter to AGA are still unclear. Hair density and hair diameter were investigated in Japanese men with or without AGA to elucidate the importance of these factors in the balding process. Male Japanese subjects with or without AGA (n = 369) were included in this study. Hair appearance at the vertex was evaluated by comparison with a series of standard photographs. Hair density was measured using a phototrichogram-based videomicroscopy technique, and hair diameter was assessed by comparison with a series of calibrated threads on the phototrichogram image. All subjects with AGA were ≥ 25 years of age. The mean percentage of thick hairs (> 80 μm) in all subjects with AGA was significantly lower than that in subjects without AGA aged ≥ 25 years (P < 0·01), but the mean percentage of vellus hairs (< 40 μm) in subjects with AGA was significantly higher (P < 0·001). By contrast, the mean density of the hair in all patients with AGA did not significantly differ from the density of those without AGA aged ≥ 25 years. However, the mean density of the hair in subjects without AGA aged < 25 years was significantly higher than that of both subjects without AGA aged ≥ 25 years (P < 0·001) and all subjects with AGA. Hair loss in men with AGA results mainly from the miniaturization of hair follicles rather than the loss of hair (shedding), at least for individuals who are ≥ 25 years of age and present with AGA. © 2014 British Association of Dermatologists.

Accelerated Mutation Accumulation in Asexual Lineages of a Freshwater Snail

PubMed Central

Neiman, Maurine; Hehman, Gery; Miller, Joseph T.; Logsdon, John M.; Taylor, Douglas R.

2010-01-01

Sexual reproduction is both extremely costly and widespread relative to asexual reproduction, meaning that it must also confer profound advantages in order to persist. One theorized benefit of sex is that it facilitates the clearance of harmful mutations, which would accumulate more rapidly in the absence of recombination. The extent to which ineffective purifying selection and mutation accumulation are direct consequences of asexuality and whether the accelerated buildup of harmful mutations in asexuals can occur rapidly enough to maintain sex within natural populations, however, remain as open questions. We addressed key components of these questions by estimating the rate of mutation accumulation in the mitochondrial genomes of multiple sexual and asexual representatives of Potamopyrgus antipodarum, a New Zealand snail characterized by mixed sexual/asexual populations. We found that increased mutation accumulation is associated with asexuality and occurs rapidly enough to be detected in recently derived asexual lineages of P. antipodarum. Our results demonstrate that increased mutation accumulation in asexuals can differentially affect coexisting and ecologically similar sexual and asexual lineages. The accelerated rate of mutation accumulation observed in asexual P. antipodarum provides some of the most direct evidence to date for a link between asexuality and mutation accumulation and implies that mutational buildup could be rapid enough to contribute to the short-term evolutionary mechanisms that favor sexual reproduction. PMID:19995828

No sex in fungus-farming ants or their crops.

PubMed

Himler, Anna G; Caldera, Eric J; Baer, Boris C; Fernández-Marín, Hermógenes; Mueller, Ulrich G

2009-07-22

Asexual reproduction imposes evolutionary handicaps on asexual species, rendering them prone to extinction, because asexual reproduction generates novel genotypes and purges deleterious mutations at lower rates than sexual reproduction. Here, we report the first case of complete asexuality in ants, the fungus-growing ant Mycocepurus smithii, where queens reproduce asexually but workers are sterile, which is doubly enigmatic because the clonal colonies of M. smithii also depend on clonal fungi for food. Degenerate female mating anatomy, extensive field and laboratory surveys, and DNA fingerprinting implicate complete asexuality in this widespread ant species. Maternally inherited bacteria (e.g. Wolbachia, Cardinium) and the fungal cultivars can be ruled out as agents inducing asexuality. M. smithii societies of clonal females provide a unique system to test theories of parent-offspring conflict and reproductive policing in social insects. Asexuality of both ant farmer and fungal crop challenges traditional views proposing that sexual farmer ants outpace coevolving sexual crop pathogens, and thus compensate for vulnerabilities of their asexual crops. Either the double asexuality of both farmer and crop may permit the host to fully exploit advantages of asexuality for unknown reasons or frequent switching between crops (symbiont reassociation) generates novel ant-fungus combinations, which may compensate for any evolutionary handicaps of asexuality in M. smithii.

Sexual Fantasy and Masturbation Among Asexual Individuals: An In-Depth Exploration.

PubMed

Yule, Morag A; Brotto, Lori A; Gorzalka, Boris B

2017-01-01

Human asexuality is generally defined as a lack of sexual attraction. We used online questionnaires to investigate reasons for masturbation, and explored and compared the contents of sexual fantasies of asexual individuals (identified using the Asexual Identification Scale) with those of sexual individuals. A total of 351 asexual participants (292 women, 59 men) and 388 sexual participants (221 women, 167 men) participated. Asexual women were significantly less likely to masturbate than sexual women, sexual men, and asexual men. Asexual women were less likely to report masturbating for sexual pleasure or fun than their sexual counterparts, and asexual men were less likely to report masturbating for sexual pleasure than sexual men. Both asexual women and men were significantly more likely than sexual women and men to report that they had never had a sexual fantasy. Of those who have had a sexual fantasy, asexual women and men were significantly more likely to endorse the response "my fantasies do not involve other people" compared to sexual participants, and consistently scored each sexual fantasy on a questionnaire as being less sexually exciting than did sexual participants. When using an open-ended format, asexual participants were more likely to report having fantasies about sexual activities that did not involve themselves, and were less likely to fantasize about topics such as group sex, public sex, and having an affair. Interestingly, there was a large amount of overlap between sexual fantasies of asexual and sexual participants. Notably, both asexual and sexual participants (both men and women) were equally likely to fantasize about topics such as fetishes and BDSM.

A simple mathematical model of gradual Darwinian evolution: emergence of a Gaussian trait distribution in adaptation along a fitness gradient.

PubMed

Biktashev, Vadim N

2014-04-01

We consider a simple mathematical model of gradual Darwinian evolution in continuous time and continuous trait space, due to intraspecific competition for common resource in an asexually reproducing population in constant environment, while far from evolutionary stable equilibrium. The model admits exact analytical solution. In particular, Gaussian distribution of the trait emerges from generic initial conditions.

Is biomass a reliable estimate of plant fitness?1

PubMed Central

Younginger, Brett S.; Sirová, Dagmara; Cruzan, Mitchell B.; Ballhorn, Daniel J.

2017-01-01

The measurement of fitness is critical to biological research. Although the determination of fitness for some organisms may be relatively straightforward under controlled conditions, it is often a difficult or nearly impossible task in nature. Plants are no exception. The potential for long-distance pollen dispersal, likelihood of multiple reproductive events per inflorescence, varying degrees of reproductive growth in perennials, and asexual reproduction all confound accurate fitness measurements. For these reasons, biomass is frequently used as a proxy for plant fitness. However, the suitability of indirect fitness measurements such as plant size is rarely evaluated. This review outlines the important associations between plant performance, fecundity, and fitness. We make a case for the reliability of biomass as an estimate of fitness when comparing conspecifics of the same age class. We reviewed 170 studies on plant fitness and discuss the metrics commonly employed for fitness estimations. We find that biomass or growth rate are frequently used and often positively associated with fecundity, which in turn suggests greater overall fitness. Our results support the utility of biomass as an appropriate surrogate for fitness under many circumstances, and suggest that additional fitness measures should be reported along with biomass or growth rate whenever possible. PMID:28224055

Characterization of Streptomyces spp. isolated from the rhizosphere of oil palm and evaluation of their ability to suppress basal stem rot disease in oil palm seedlings when applied as powder formulations in a glasshouse trial.

PubMed

Shariffah-Muzaimah, S A; Idris, A S; Madihah, A Z; Dzolkhifli, O; Kamaruzzaman, S; Maizatul-Suriza, M

2017-12-18

Ganoderma boninense, the main causal agent of oil palm (Elaeis guineensis) basal stem rot (BSR), severely reduces oil palm yields around the world. To reduce reliance on fungicide applications to control BSR, we are investigating the efficacy of alternative control methods, such as the application of biological control agents. In this study, we used four Streptomyces-like actinomycetes (isolates AGA43, AGA48, AGA347 and AGA506) that had been isolated from the oil palm rhizosphere and screened for antagonism towards G. boninense in a previous study. The aim of this study was to characterize these four isolates and then to assess their ability to suppress BSR in oil palm seedlings when applied individually to the soil in a vermiculite powder formulation. Analysis of partial 16S rRNA gene sequences (512 bp) revealed that the isolates exhibited a very high level of sequence similarity (> 98%) with GenBank reference sequences. Isolates AGA347 and AGA506 showed 99% similarity with Streptomyces hygroscopicus subsp. hygroscopicus and Streptomyces ahygroscopicus, respectively. Isolates AGA43 and AGA48 also belonged to the Streptomyces genus. The most effective formulation, AGA347, reduced BSR in seedlings by 73.1%. Formulations using the known antifungal producer Streptomyces noursei, AGA043, AGA048 or AGA506 reduced BSR by 47.4, 30.1, 54.8 and 44.1%, respectively. This glasshouse trial indicates that these Streptomyces spp. show promise as potential biological control agents against Ganoderma in oil palm. Further investigations are needed to determine the mechanism of antagonism and to increase the shelf life of Streptomyces formulations.

Physiological and subjective sexual arousal in self-identified asexual women.

PubMed

Brotto, Lori A; Yule, Morag A

2011-08-01

Asexuality can be defined as a lifelong lack of sexual attraction. Empirical research on asexuality reveals significantly lower self-reported sexual desire and arousal and lower rates of sexual activity; however, the speculation that there may also be an impaired psychophysiological sexual arousal response has never been tested. The aim of this study was to compare genital (vaginal pulse amplitude; VPA) and subjective sexual arousal in asexual and non-asexual women. Thirty-eight women between the ages of 19 and 55 years (10 heterosexual, 10 bisexual, 11 homosexual, and 7 asexual) viewed neutral and erotic audiovisual stimuli while VPA and self-reported sexual arousal and affect were measured. There were no significant group differences in the increased VPA and self-reported sexual arousal response to the erotic film between the groups. Asexuals showed significantly less positive affect, sensuality-sexual attraction, and self-reported autonomic arousal to the erotic film compared to the other groups; however, there were no group differences in negative affect or anxiety. Genital-subjective sexual arousal concordance was significantly positive for the asexual women and non-significant for the other three groups, suggesting higher levels of interoceptive awareness among asexuals. Taken together, the findings suggest normal subjective and physiological sexual arousal capacity in asexual women and challenge the view that asexuality should be characterized as a sexual dysfunction.

Compulsory sexuality.

PubMed

Emens, Elizabeth F

2014-02-01

Asexuality is an emerging identity category that challenges the common assumption that everyone is defined by some type of sexual attraction. Asexuals--those who report feeling no sexual attraction to others--constitute one percent of the population, according to one prominent study. In recent years, some individuals have begun to identify as asexual and to connect around their experiences interacting with a sexual society. Asexuality has also become a protected classification under the antidiscrimination law of one state and several localities, but legal scholarship has thus far neglected the subject. This Article introduces asexuality to the legal literature as a category of analysis, an object of empirical study, and a phenomenon of medical science. It then offers a close examination of the growing community of self-identified asexuals. Asexual identity has revealing intersections with the more familiar categories of gender, sexual orientation, and disability, and inspires new models for understanding sexuality. Thinking about asexuality also sheds light on our legal system. Ours is arguably a sexual law, predicated on the assumption that sex is important. This Article uses asexuality to develop a framework for identifying the ways that law privileges sexuality. Across various fields, these interactions include legal requirements of sexual activity, special carve-outs to shield sexuality from law, legal protections from others' sexuality, and legal protections for sexual identity. Applying this framework, the Article traces several ways that our sexual law burdens, and occasionally benefits, asexuals. This Article concludes by closely examining asexuality's prospects for broader inclusion into federal, state, and local antidiscrimination laws.

Exploiting the Adaptation Dynamics to Predict the Distribution of Beneficial Fitness Effects

PubMed Central

2016-01-01

Adaptation of asexual populations is driven by beneficial mutations and therefore the dynamics of this process, besides other factors, depends on the distribution of beneficial fitness effects. It is known that on uncorrelated fitness landscapes, this distribution can only be of three types: truncated, exponential and power law. We performed extensive stochastic simulations to study the adaptation dynamics on rugged fitness landscapes, and identified two quantities that can be used to distinguish the underlying distribution of beneficial fitness effects. The first quantity studied here is the fitness difference between successive mutations that spread in the population, which is found to decrease in the case of truncated distributions, remains nearly a constant for exponentially decaying distributions and increases when the fitness distribution decays as a power law. The second quantity of interest, namely, the rate of change of fitness with time also shows quantitatively different behaviour for different beneficial fitness distributions. The patterns displayed by the two aforementioned quantities are found to hold good for both low and high mutation rates. We discuss how these patterns can be exploited to determine the distribution of beneficial fitness effects in microbial experiments. PMID:26990188

EXPERIMENTAL STUDIES OF THE EVOLUTIONARY SIGNIFICANCE OF SEXUAL REPRODUCTION. V. A FIELD TEST OF THE SIB-COMPETITION LOTTERY HYPOTHESIS.

PubMed

Kelley, Steven E

1989-08-01

Sexually and asexually derived tillers of Anthoxanthum odoratum were planted directly in the field to test the hypothesis that competition among groups of sexual and asexual siblings favors the maintenance of sexual reproduction in populations. The results showed a substantial fitness advantage for sexual tillers. However, in contrast with the models, the advantage of sex did not increase with increasing numbers of colonists in the patch, there were multiple survivors among colonists, and an advantage was observed even for singly planted tillers. When a truncation-selection scheme was imposed ex post facto on the data, the relative performance of sexual tillers was similar to that predicted by the Bulmer (1980) model, suggesting that sib-competition models fail due to the violation of the assumption of truncation selection. The advantage of sex was not correlated with the presence of other species, total percentage cover, or species diversity, although sites where sex was favored were physically clustered. © 1989 The Society for the Study of Evolution.

Role of epistasis on the fixation probability of a non-mutator in an adapted asexual population.

PubMed

James, Ananthu

2016-10-21

The mutation rate of a well adapted population is prone to reduction so as to have a lower mutational load. We aim to understand the role of epistatic interactions between the fitness affecting mutations in this process. Using a multitype branching process, the fixation probability of a single non-mutator emerging in a large asexual mutator population is analytically calculated here. The mutator population undergoes deleterious mutations at constant, but at a much higher rate than that of the non-mutator. We find that antagonistic epistasis lowers the chances of mutation rate reduction, while synergistic epistasis enhances it. Below a critical value of epistasis, the fixation probability behaves non-monotonically with variation in the mutation rate of the background population. Moreover, the variation of this critical value of the epistasis parameter with the strength of the mutator is discussed in the appendix. For synergistic epistasis, when selection is varied, the fixation probability reduces overall, with damped oscillations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mutation load and the extinction of large populations

NASA Astrophysics Data System (ADS)

Bernardes, A. T.

1996-02-01

In the time evolution of finite populations, the accumulation of harmful mutations in further generations might lead to a temporal decay in the mean fitness of the whole population that, after sufficient time, would reduce population size and so lead to extinction. This joint action of mutation load and population reduction is called Mutational Meltdown and is usually considered only to occur in small asexual or very small sexual populations. However, the problem of extinction cannot be discussed in a proper way if one previously assumes the existence of an equilibrium state, as initially discussed in this paper. By performing simulations in a genetically inspired model for time-changing populations, we show that mutational meltdown also occurs in large asexual populations and that the mean time to extinction is a nonmonotonic function of the selection coefficient. The stochasticity of the extinction process is also discussed. The extinction of small sexual N ∼ 700 populations is shown and our results confirm the assumption that the existence of recombination might be a powerful mechanism to avoid extinction.

Linear Combination Fitting (LCF)-XANES analysis of As speciation in selected mine-impacted materials

EPA Pesticide Factsheets

This table provides sample identification labels and classification of sample type (tailings, calcinated, grey slime). For each sample, total arsenic and iron concentrations determined by acid digestion and ICP analysis are provided along with arsenic in-vitro bioaccessibility (As IVBA) values to estimate arsenic risk. Lastly, the table provides linear combination fitting results from synchrotron XANES analysis showing the distribution of arsenic speciation phases present in each sample along with fitting error (R-factor).This dataset is associated with the following publication:Ollson, C., E. Smith, K. Scheckel, A. Betts, and A. Juhasz. Assessment of arsenic speciation and bioaccessibility in mine-impacted materials. Diana Aga, Wonyong Choi, Andrew Daugulis, Gianluca Li Puma, Gerasimos Lyberatos, and Joo Hwa Tay JOURNAL OF HAZARDOUS MATERIALS. Elsevier Science Ltd, New York, NY, USA, 313: 130-137, (2016).

Asexuality: Sexual Orientation, Paraphilia, Sexual Dysfunction, or None of the Above?

PubMed

Brotto, Lori A; Yule, Morag

2017-04-01

Although lack of sexual attraction was first quantified by Kinsey, large-scale and systematic research on the prevalence and correlates of asexuality has only emerged over the past decade. Several theories have been posited to account for the nature of asexuality. The goal of this review was to consider the evidence for whether asexuality is best classified as a psychiatric syndrome (or a symptom of one), a sexual dysfunction, or a paraphilia. Based on the available science, we believe there is not sufficient evidence to support the categorization of asexuality as a psychiatric condition (or symptom of one) or as a disorder of sexual desire. There is some evidence that a subset of self-identified asexuals have a paraphilia. We also considered evidence supporting the classification of asexuality as a unique sexual orientation. We conclude that asexuality is a heterogeneous entity that likely meets conditions for a sexual orientation, and that researchers should further explore evidence for such a categorization.

Distribution of fixed beneficial mutations and the rate of adaptation in asexual populations

PubMed Central

Good, Benjamin H.; Rouzine, Igor M.; Balick, Daniel J.; Hallatschek, Oskar; Desai, Michael M.

2012-01-01

When large asexual populations adapt, competition between simultaneously segregating mutations slows the rate of adaptation and restricts the set of mutations that eventually fix. This phenomenon of interference arises from competition between mutations of different strengths as well as competition between mutations that arise on different fitness backgrounds. Previous work has explored each of these effects in isolation, but the way they combine to influence the dynamics of adaptation remains largely unknown. Here, we describe a theoretical model to treat both aspects of interference in large populations. We calculate the rate of adaptation and the distribution of fixed mutational effects accumulated by the population. We focus particular attention on the case when the effects of beneficial mutations are exponentially distributed, as well as on a more general class of exponential-like distributions. In both cases, we show that the rate of adaptation and the influence of genetic background on the fixation of new mutants is equivalent to an effective model with a single selection coefficient and rescaled mutation rate, and we explicitly calculate these effective parameters. We find that the effective selection coefficient exactly coincides with the most common fixed mutational effect. This equivalence leads to an intuitive picture of the relative importance of different types of interference effects, which can shift dramatically as a function of the population size, mutation rate, and the underlying distribution of fitness effects. PMID:22371564

Evaluation of androgen receptor gene as a candidate gene in female androgenetic alopecia.

PubMed

el-Samahy, May H; Shaheen, Maha A; Saddik, Dina E B; Abdel-Fattah, Nermeen S A; el-Sawi, Mohammad A; Mahran, Manal Z; Shehab, Abeer A A

2009-06-01

Genetic polymorphisms of the androgen receptor (AR) gene have been studied in male androgenetic alopecia (AGA); however, little is known about gene polymorphism and female AGA. To evaluate the AR gene as a candidate gene for female AGA. Thirty premenopausal Egyptian female patients with AGA (mean age, 32.3 +/- 7 years) and 11 age- and sex-matched controls were included. All subjects underwent laboratory and pelvic ultrasound evaluation to exclude other precipitating cause(s) of hair loss. Scalp biopsy was taken and the AR gene was evaluated using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). According to Ludwig's classification, all patients had type II AGA. Statistical analysis showed no statistically significant difference in genotype (chi(2) = 5.513, P > or = 0.05) or allele frequency (chi(2) = 1.312, P > or = 0.05) between patients and controls. There was also no statistically significant difference between the genotype and allele frequency with disease duration. In contrast with male AGA, no association was found between type II AGA in Egyptian women and the AR gene. Therefore, the genetic study of this gene does not serve as a biomarker for the identification of women with a predisposition to AGA.

Coexistence of sexual individuals and genetically isolated asexual counterparts in a thrips.

PubMed

Kobayashi, Kazuya; Yoshimura, Jin; Hasegawa, Eisuke

2013-11-21

Sex is a paradoxical phenomenon because it is less efficient compared with asexual reproduction. To resolve this paradox we need a direct comparison between sexual and asexual forms. In many organisms, however, sexual and asexual forms do not occur in the same habitat, or at the same time. In a few cases where sexual and asexual forms are found in a single population, some (though rare) genetic exchange is usually detected between the two forms. When genetic exchange occurs a direct comparison is impossible. Here we investigate a thrips exhibiting both sexual and asexual forms (lineages) that are morphologically indistinguishable. We examine if the two forms are genetically isolated. Phylogeny based on nuclear genes confirms that the sexual and asexual lineages are genetically differentiated. Thus we demonstrate that the current system has certain advantages over existing and previously used model systems in the evolution of sexual reproduction.

Comparative toxicant sensitivity of sexual and asexual reproduction in the rotifer Brachionus calyciflorus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snell, T.W.; Carmona, M.J.

Cyclically parthenogenetic zooplankters like rotifers are important tools for assessing toxicity in aquatic environments. Sexual reproduction is an essential component of rotifer life cycles, but current toxicity tests utilize only asexual reproduction. The authors compared the effects of four toxicants on asexual and sexual reproduction of the rotifer Brachionus calyciflorus. Toxicants had a differential effect on sexual and asexual reproduction, with sexual reproduction consistently the most sensitive. Concentrations of 0.2 {mu}g/ml PCP (sodium pentachlorophenate) had no effect on the asexual reproductive rate, but significantly reduced sexual reproduction. Likewise, chlorpyrifos concentrations of 0.3 {mu}g/ml had no significant effect on asexual reproduction,more » but sexual reproduction was significantly reduced. There was no difference in NOECs, LOECs, and chronic values for asexual and sexual reproduction for cadmium and naphthol tests. However, comparison of toxicant effect levels revealed that sexual reproduction was more strongly reduced at each toxicant concentration. The four toxicants tested inhibited sexual reproduction 2 to 68 times more than asexual reproduction at the lowest observed effect concentrations. Toxicants inhibited sexual reproduction in its initial step: sexual female production. Because sexual reproduction is more sensitive, toxicity tests based exclusively on asexual reproduction may not be protective of rotifer life cycles.« less

Genetic Control of Contagious Asexuality in the Pea Aphid

PubMed Central

Jaquiéry, Julie; Stoeckel, Solenn; Larose, Chloé; Nouhaud, Pierre; Rispe, Claude; Mieuzet, Lucie; Bonhomme, Joël; Mahéo, Frédérique; Legeai, Fabrice; Gauthier, Jean-Pierre; Prunier-Leterme, Nathalie; Tagu, Denis; Simon, Jean-Christophe

2014-01-01

Although evolutionary transitions from sexual to asexual reproduction are frequent in eukaryotes, the genetic bases of such shifts toward asexuality remain largely unknown. We addressed this issue in an aphid species where both sexual and obligate asexual lineages coexist in natural populations. These sexual and asexual lineages may occasionally interbreed because some asexual lineages maintain a residual production of males potentially able to mate with the females produced by sexual lineages. Hence, this species is an ideal model to study the genetic basis of the loss of sexual reproduction with quantitative genetic and population genomic approaches. Our analysis of the co-segregation of ∼300 molecular markers and reproductive phenotype in experimental crosses pinpointed an X-linked region controlling obligate asexuality, this state of character being recessive. A population genetic analysis (>400-marker genome scan) on wild sexual and asexual genotypes from geographically distant populations under divergent selection for reproductive strategies detected a strong signature of divergent selection in the genomic region identified by the experimental crosses. These population genetic data confirm the implication of the candidate region in the control of reproductive mode in wild populations originating from 700 km apart. Patterns of genetic differentiation along chromosomes suggest bidirectional gene flow between populations with distinct reproductive modes, supporting contagious asexuality as a prevailing route to permanent parthenogenesis in pea aphids. This genetic system provides new insights into the mechanisms of coexistence of sexual and asexual aphid lineages. PMID:25473828

Asexuality Development among Middle Aged and Older Men

PubMed Central

Huang, Yan-Ping; Chen, Bin; Ping, Ping; Wang, Hong-Xiang; Hu, Kai; Yang, Hao; Zhang, Tao; Feng, Tan; Jin, Yan; Han, Yin-Fa; Wang, Yi-Xin; Huang, Yi-Ran

2014-01-01

Objectives To assess erectile function in middle-aged and older men with asexuality status and further analyze their specific reasons for this condition. Subjects and Methods Men who had regular sexual intercourse attempts (sex frequency≥1 time per month) were classified into mild erectile dysfunction (ED), moderate to severe ED and non-ED according to International Index of Erectile Function-5, and men having no sexual intercourse attempts for at least 6 months were defined as having an asexuality status. The risk factors associated with ED were collected in a sample of 1,531 Chinese men aged 40 to 80 years, and the self-report reasons for asexuality were recorded in asexual cohort individually. Comparative analyses and multivariate regression models were conducted among these groups. Results The prevalence rates of ED and asexuality status were 49.9% and 37.2%. The asexuality status group had higher risk factors than the moderate to severe ED group in terms of old age (age≥65, adjusted odds ratio (OR) 17.69 versus (Vs.) 7.19), diabetes (crude OR: 2.40 Vs. 2.36) and hypertension (crude OR: 1.78 Vs. 1.72). The specific reasons for the asexuality status were “erectile difficulty” (52.9%), “do not care about sexuality” (53.5%)”, “no longer necessary to have sexuality at this age” (47.7%), “severe stress” (44.4%), “severe fatigue” (26.3%) and “masturbation” (26.9%). Conclusions Men with an asexual status suffer from higher risk factors for ED than men with moderate to severe ED. The majority of this asexual status could be attributed to a full ED, although the reasons for this transient asexuality also involved sexual attitudes and interests, sexual partners and masturbation. PMID:24667838

Population density shapes patterns of survival and reproduction in Eleutheria dichotoma (Hydrozoa: Anthoathecata).

PubMed

Dańko, Aleksandra; Schaible, Ralf; Pijanowska, Joanna; Dańko, Maciej J

2018-01-01

Budding hydromedusae have high reproductive rates due to asexual reproduction and can occur in high population densities along the coasts, specifically in tidal pools. In laboratory experiments, we investigated the effects of population density on the survival and reproductive strategies of a single clone of Eleutheria dichotoma . We found that sexual reproduction occurs with the highest rate at medium population densities. Increased sexual reproduction was associated with lower budding (asexual reproduction) and survival probability. Sexual reproduction results in the production of motile larvae that can, in contrast to medusae, seek to escape unfavorable conditions by actively looking for better environments. The successful settlement of a larva results in starting the polyp stage, which is probably more resistant to environmental conditions. This is the first study that has examined the life-history strategies of the budding hydromedusa E. dichotoma by conducting a long-term experiment with a relatively large sample size that allowed for the examination of age-specific mortality and reproductive rates. We found that most sexual and asexual reproduction occurred at the beginning of life following a very rapid process of maturation. The parametric models fitted to the mortality data showed that population density was associated with an increase in the rate of aging, an increase in the level of late-life mortality plateau, and a decrease in the hidden heterogeneity in individual mortality rates. The effects of population density on life-history traits are discussed in the context of resource allocation and the r/K-strategies' continuum concept.

Deletion of a non-catalytic region increases the enzymatic activity of a β-agarase from Flammeovirga sp. MY04

NASA Astrophysics Data System (ADS)

Han, Wenjun; Gu, Jingyan; Liu, Huihui; Li, Fuchuan; Wu, Zhihong; Li, Yuezhong

2015-10-01

A Glycoside hydrolase (GH) typically contains one catalytic module and varied non-catalytic regions (NCRs). However, effects of the NCRs to the catalytic modules remain mostly unclear except the carbohydrate-binding modules (CBMs). AgaG4 is a GH16 endo- β-agarase of the agarolytic marine bacterium Flammeovirga sp. MY04. The enzyme consists of an extra sugar-binding peptide within the catalytic module, with no predictable CBMs but function-unknown sequences in the NCR, which is a new characteristic of agarase sequences. In this study, we deleted the NCR sequence, a 140-amino acid peptide at the C-terminus and expressed the truncated gene, agaG4-T140, in Escherichia coli. After purification and refolding, the truncated agarase rAgaG4-T140 retained the same catalytic temperature and pH value as rAgaG4. Using combined fluorescent labeling, HPLC and MS/MS techniques, we identified the end-products of agarose degradation by rAgaG4-T140 as neoagarotetraose and neoagarohexaose, with a final molar ratio of 1.53:1 and a conversion ratio of approximately 70%, which were similar to those of rAgaG4. However, the truncated agarase rAgaG4-T140 markedly decreased in protein solubility by 15 times and increased in enzymatic activities by 35 times. The oligosaccharide production of rAgaG4-T140 was approximately 25 times the weight of that produced by equimolar rAgaG4. This study provides some insights into the influences of NCR on the biochemical characteristics of agarase AgaG4 and implies some new strategies to improve the properties of a GH enzyme.

Understanding patient and physician perceptions of male androgenetic alopecia treatments in Asia-Pacific and Latin America.

PubMed

Lulic, Zrinka; Inui, Shigeki; Sim, Woo-Young; Kang, Hoon; Choi, Gwang Seong; Hong, Woosung; Hatanaka, Toshiki; Wilson, Timothy; Manyak, Michael

2017-08-01

This survey aimed to explore patient and physician attitudes towards male androgenetic alopecia (AGA), satisfaction with currently available male AGA treatments and investigate the factors affecting treatment choice. The survey was carried out in five countries (Japan, South Korea, Taiwan, Mexico and Brazil) between November and December 2015 using a standard market research methodology. Questionnaires were completed by patients with male AGA or hair loss/thinning and practicing physicians who were responsible for prescribing AGA treatment. In total, 835 patients and 338 physicians completed the questionnaire. Overall, 37.6% of patients reported satisfaction with the treatments they had used. The highest patient satisfaction was reported for 5-alpha-reductase inhibitors (53.9% of patients satisfied). In all countries, physicians were more likely than patients to think that male AGA has a major impact on patient confidence (89.3% vs 70.4%, respectively). There was agreement by physicians and patients that male AGA patients who are involved in their treatment decisions have better outcomes. Patients who were satisfied with AGA treatments were more likely to have the level of involvement they desired in treatment decisions (69.1% of satisfied patients) than dissatisfied patients (56.4% of dissatisfied patients). This survey provides valuable insights into the attitudes of patients and physicians in Asia and Latin America about male AGA and its treatments. The survey identified areas of disconnect between physicians and patients regarding the impact of male AGA, treatment consultations and the importance of treatment attributes. It also highlights the need for physicians to spend sufficient time with patients discussing AGA treatment approaches. © 2017 GlaxoSmithKline. The Journal of Dermatology published by John Wiley & Sons Australia, Ltd on behalf of Japanese Dermatological Association.

Cryptic sexual populations account for genetic diversity and ecological success in a widely distributed, asexual fungus-growing ant.

PubMed

Rabeling, Christian; Gonzales, Omar; Schultz, Ted R; Bacci, Maurício; Garcia, Marcos V B; Verhaagh, Manfred; Ishak, Heather D; Mueller, Ulrich G

2011-07-26

Sex and recombination are central processes in life generating genetic diversity. Organisms that rely on asexual propagation risk extinction due to the loss of genetic diversity and the inability to adapt to changing environmental conditions. The fungus-growing ant species Mycocepurus smithii was thought to be obligately asexual because only parthenogenetic populations have been collected from widely separated geographic localities. Nonetheless, M. smithii is ecologically successful, with the most extensive distribution and the highest population densities of any fungus-growing ant. Here we report that M. smithii actually consists of a mosaic of asexual and sexual populations that are nonrandomly distributed geographically. The sexual populations cluster along the Rio Amazonas and the Rio Negro and appear to be the source of independently evolved and widely distributed asexual lineages, or clones. Either apomixis or automixis with central fusion and low recombination rates is inferred to be the cytogenetic mechanism underlying parthenogenesis in M. smithii. Males appear to be entirely absent from asexual populations, but their existence in sexual populations is indicated by the presence of sperm in the reproductive tracts of queens. A phylogenetic analysis of the genus suggests that M. smithii is monophyletic, rendering a hybrid origin of asexuality unlikely. Instead, a mitochondrial phylogeny of sexual and asexual populations suggests multiple independent origins of asexual reproduction, and a divergence-dating analysis indicates that M. smithii evolved 0.5-1.65 million years ago. Understanding the evolutionary origin and maintenance of asexual reproduction in this species contributes to a general understanding of the adaptive significance of sex.

Freedom, invisibility, and community: a qualitative study of self-identification with asexuality.

PubMed

MacNeela, Pádraig; Murphy, Aisling

2015-04-01

A significant body of research is now emerging on the subjective meaning of asexuality. This study explored how self-identification as asexual is managed, both as a threat to the self-concept and a source of personal meaning. A total of 66 self-identified asexuals were recruited from an asexuality internet community and responded to open-ended questions on an online survey. Of these, 31 participants identified as female, 15 as male, 18 gave a different label such as genderqueer or androgynous, and two did not provide information on gender. A thematic analysis of the transcripts resulted in three themes. Socially, asexuality attracted denial and resistance due to incompatibility with heteronormative societal expectations. Despite the threat to self-integrity arising from asexuality being socially rejected, it was typically assimilated as a valued and meaningful orientation on an intra-personal level, aided by information and support from the online community. A second level of threat to self arose whereby other self-identifications, especially gender, had to be reconciled with a non-sexual persona. The accommodation made to other elements of the self was reflected in complex sub-identities. The findings were interpreted using identity process theory to understand how threats arising from self-identifying as asexual are managed. Although asexuality emerges as an orientation to sexuality that can be reconciled with the self, its invisibility or outright rejection in society constitute an on-going challenge.

Characterization of Ca2+ channel currents in cultured rat cerebellar granule neurones.

PubMed

Pearson, H A; Sutton, K G; Scott, R H; Dolphin, A C

1995-02-01

1. High-threshold voltage-gated calcium channel currents (IBa) were studied in cultured rat cerebellar granule neurones using the whole-cell patch clamp technique with 10 mM Ba2+ as the charge carrier. The putative P-type component of whole-cell current was characterized by utilizing the toxin omega-agatoxin IVA (omega-Aga IVA) in combination with other blockers. 2. omega-Aga IVA (100 nM) inhibited the high voltage-activated (HVA) IBa by 40.9 +/- 3.4% (n = 27), and the dissociation constant Kd was 2.7 nM. Maximal inhibition occurred within a 2-3 min time course, and was irreversible. The isolated omega-Aga IVA-sensitive current was non-inactivating. 3. omega-Aga IVA exhibited overlapping selectivity with both N- and L-channel blockers; omega-conotoxin GVIA (omega-CTX GVIA) (1 microM) and the dihydropyridine (-)-202-709 (1 microM), respectively. Together these toxins reduced the omega-Aga IVA-sensitive component to just 4.5 +/- 1.4% (n = 3). Thus only a small proportion of the current can be unequivocally attributed to P-type current. Inhibition of the HVA IBa by omega-Aga IA also reduced the proportion of omega-Aga IVA-sensitive current to 28.0 +/- 3.2% (n = 3). 4. Application of omega-Aga IVA and a synthetic form of funnel-web toxin, N-(7-amino-4-azaheptyl)-L-argininamide (sFTX-3.3; 10 microM), produced an additive block of the HVA IBa. Consequently these two toxins do not act on the same channel in cerebellar granule neurones. 5. omega-Aga IVA inhibition of low voltage-activated (LVA) IBa was studied in the ND7-23 neuronal cell line. omega-Aga IVA (100 nM) reduced the LVA current by 41.3 +/- 3.2% (n = 17) in a fully reversible manner with no shift in the steady-state inactivation of the channel. 6. A component of current insensitive to N-, L- and P-channel blockers remained unclassified in all our studies. This component, and also that remaining following block by omega-Aga IVA and omega-Aga IA, exhibited relatively rapid, although incomplete, inactivation compared to the other currents isolated in this study. 7. In conclusion, omega-Aga IVA inhibits a component of current in cultured cerebellar granule neurones which overlaps almost completely with that inhibited by L- and N-channel blockers. In addition, a large component of whole-cell current in these neurones still remains unclassified.

Correlation between anatomy of the scapula and the incidence of rotator cuff tear and glenohumeral osteoarthritis via radiological study.

PubMed

Miswan, Mohd Fairudz Bin Mohd; Saman, Mohd Shahril Bin Ahmad; Hui, Teo Seow; Al-Fayyadh, Mohamed Zubair Mohamed; Ali, Mohamed Razif Bin Mohamed; Min, Ng Wuey

2017-01-01

We conducted a study to elucidate the correlation between the anatomy of the shoulder joint with the development of rotator cuff tear (RCT) and glenohumeral osteoarthritis (GHOA) by using acromioglenoid angle (AGA). The AGA is a new measured angle formed between the line from midglenoid to lateral end of the acromion with the line parallel to the glenoid surface. The AGA was measured in a group of 85 shoulders with RCT, 49 with GHOA and 103 non-RCT/GHOA control shoulders. The AGA was compared with other radiological parameters, such as, the critical shoulder angle (CSA), the acromion index (AI) and the acromiohumeral interval (AHI). Correlational and regression analysis were performed using SPSS 20. The mean AGA was 50.9° (45.2-56.5°) in the control group, 53.3° (47.6-59.1°) in RCT group and 45.5° (37.7-53.2°) in OA group. Among patients with AGA > 51.5°, 61% were in the RCT group and among patients with AGA < 44.5°, 56% were in OA group. Pearson correlation analysis had shown significant correlation between AGA and CSA ( r = 0.925, p < 0.001). It was also significant of AHI in RCT group with mean 6.6 mm (4.7-8.5 mm) and significant AI in OA group with mean 0.68 (0.57-0.78) with p value < 0.001 respectively. The AGA method of measurement is an excellent predictive parameter for diagnosing RCT and GHOA.

Recurrent loss of sex is associated with accumulation of deleterious mutations in Oenothera.

PubMed

Hollister, Jesse D; Greiner, Stephan; Wang, Wei; Wang, Jun; Zhang, Yong; Wong, Gane Ka-Shu; Wright, Stephen I; Johnson, Marc T J

2015-04-01

Sexual reproduction is nearly universal among eukaryotes. Theory predicts that the rarity of asexual eukaryotic species is in part caused by accumulation of deleterious mutations and heightened extinction risk associated with suppressed recombination and segregation in asexual species. We tested this prediction with a large data set of 62 transcriptomes from 29 species in the plant genus Oenothera, spanning ten independent transitions between sexual and a functionally asexual genetic system called permanent translocation heterozygosity. Illumina short-read sequencing and de novo transcript assembly yielded an average of 16.4 Mb of sequence per individual. Here, we show that functionally asexual species accumulate more deleterious mutations than sexual species using both population genomic and phylogenetic analysis. At an individual level, asexual species exhibited 1.8 × higher heterozygosity than sexual species. Within species, we detected a higher proportion of nonsynonymous polymorphism relative to synonymous variation within asexual compared with sexual species, indicating reduced efficacy of purifying selection. Asexual species also exhibited a greater proportion of transcripts with premature stop codons. The increased proportion of nonsynonymous mutations was also positively correlated with divergence time between sexual and asexual species, consistent with Muller's ratchet. Between species, we detected repeated increases in the ratio of nonsynonymous to synonymous divergence in asexual species compared with sexually reproducing sister taxa, indicating increased accumulation of deleterious mutations. These results confirm that an important advantage of sex is that it facilitates selection against deleterious alleles, which might help to explain the dearth of extant asexual species. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Origination of asexual plantlets in three species of Crassulaceae.

PubMed

Guo, Jiansheng; Liu, Hailiang; He, Yangyang; Cui, Xianghuan; Du, Xiling; Zhu, Jian

2015-03-01

During asexual plant reproduction, cells from different organs can be reprogrammed to produce new individuals, a process that requires the coordination of cell cycle reactivation with the acquisition of other cellular morphological characteristics. However, the factors that influence the variety of asexual reproduction have not yet been determined. Here, we report on plantlet formation in Kalanchoe daigremontiana, Graptopetalum paraguayense, and Crassula portulacea (Crassulaceae) and analyse the effect of initiating cells on asexual reproduction in these three species. Additionally, the roles of WUSCHEL (WUS) and CUP-SHAPED COTYLEDON 1 (CUC1) in the asexual reproduction of these species were analysed through qRT-PCR. Our results indicated that pre-existing stem cell-like cells at the sites of asexual reproduction were responsible for the formation of plantlets. These cells were arrested in different phases of the cell cycle and showed different cell morphological characteristics and cell counts. The accumulation of auxin and cytokinin at the sites of asexual plantlet formation indicated their important functions, particularly for cell cycle reactivation. These differences may influence the pattern and complexity of asexual reproduction in these Crassulaceae species. Additionally, the dynamic expression levels of CUC1 and WUS may indicate that CUC1 functions in the formation of callus and shoot meristems; whereas, WUS was only associated with shoot induction.

Blood Plasma-Derived Anti-Glycan Antibodies to Sialylated and Sulfated Glycans Identify Ovarian Cancer Patients

PubMed Central

Pochechueva, Tatiana; Chinarev, Alexander; Schoetzau, Andreas; Fedier, André; Bovin, Nicolai V.; Hacker, Neville F.; Jacob, Francis; Heinzelmann-Schwarz, Viola

2016-01-01

Altered levels of naturally occurring anti-glycan antibodies (AGA) circulating in human blood plasma are found in different pathologies including cancer. Here the levels of AGA directed against 22 negatively charged (sialylated and sulfated) glycans were assessed in high-grade serous ovarian cancer (HGSOC, n = 22) patients and benign controls (n = 31) using our previously developed suspension glycan array (SGA). Specifically, the ability of AGA to differentiate between controls and HGSOC, the most common and aggressive type of ovarian cancer with a poor outcome was determined. Results were compared to CA125, the commonly used ovarian cancer biomarker. AGA to seven glycans that significantly (P<0.05) differentiated between HGSOC and control were identified: AGA to top candidates SiaTn and 6-OSulfo-TF (both IgM) differentiated comparably to CA125. The area under the curve (AUC) of a panel of AGA to 5 glycans (SiaTn, 6-OSulfo-TF, 6-OSulfo-LN, SiaLea, and GM2) (0.878) was comparable to CA125 (0.864), but it markedly increased (0.985) when combined with CA125. AGA to SiaTn and 6-OSulfo-TF were also valuable predictors for HGSOC when CA125 values appeared inconclusive, i.e. were below a certain threshold. AGA-glycan binding was in some cases isotype-dependent and sensitive to glycosidic linkage switch (α2–6 vs. α2–3), to sialylation, and to sulfation of the glycans. In conclusion, plasma-derived AGA to sialylated and sulfated glycans including SiaTn and 6-OSulfo-TF detected by SGA present a valuable alternative to CA125 for differentiating controls from HGSOC patients and for predicting the likelihood of HGSOC, and may be potential HGSOC tumor markers. PMID:27764122

Blood Plasma-Derived Anti-Glycan Antibodies to Sialylated and Sulfated Glycans Identify Ovarian Cancer Patients.

PubMed

Pochechueva, Tatiana; Chinarev, Alexander; Schoetzau, Andreas; Fedier, André; Bovin, Nicolai V; Hacker, Neville F; Jacob, Francis; Heinzelmann-Schwarz, Viola

2016-01-01

Altered levels of naturally occurring anti-glycan antibodies (AGA) circulating in human blood plasma are found in different pathologies including cancer. Here the levels of AGA directed against 22 negatively charged (sialylated and sulfated) glycans were assessed in high-grade serous ovarian cancer (HGSOC, n = 22) patients and benign controls (n = 31) using our previously developed suspension glycan array (SGA). Specifically, the ability of AGA to differentiate between controls and HGSOC, the most common and aggressive type of ovarian cancer with a poor outcome was determined. Results were compared to CA125, the commonly used ovarian cancer biomarker. AGA to seven glycans that significantly (P<0.05) differentiated between HGSOC and control were identified: AGA to top candidates SiaTn and 6-OSulfo-TF (both IgM) differentiated comparably to CA125. The area under the curve (AUC) of a panel of AGA to 5 glycans (SiaTn, 6-OSulfo-TF, 6-OSulfo-LN, SiaLea, and GM2) (0.878) was comparable to CA125 (0.864), but it markedly increased (0.985) when combined with CA125. AGA to SiaTn and 6-OSulfo-TF were also valuable predictors for HGSOC when CA125 values appeared inconclusive, i.e. were below a certain threshold. AGA-glycan binding was in some cases isotype-dependent and sensitive to glycosidic linkage switch (α2-6 vs. α2-3), to sialylation, and to sulfation of the glycans. In conclusion, plasma-derived AGA to sialylated and sulfated glycans including SiaTn and 6-OSulfo-TF detected by SGA present a valuable alternative to CA125 for differentiating controls from HGSOC patients and for predicting the likelihood of HGSOC, and may be potential HGSOC tumor markers.

Habitat heterogeneity favors asexual reproduction in natural populations of grassthrips

PubMed Central

Lavanchy, Guillaume; Strehler, Marie; Llanos Roman, Maria Noemi; Lessard‐Therrien, Malie; Humbert, Jean‐Yves; Dumas, Zoé; Jalvingh, Kirsten; Ghali, Karim; Fontcuberta García‐Cuenca, Amaranta; Zijlstra, Bart; Arlettaz, Raphaël; Schwander, Tanja

2016-01-01

Explaining the overwhelming success of sex among eukaryotes is difficult given the obvious costs of sex relative to asexuality. Different studies have shown that sex can provide benefits in spatially heterogeneous environments under specific conditions, but whether spatial heterogeneity commonly contributes to the maintenance of sex in natural populations remains unknown. We experimentally manipulated habitat heterogeneity for sexual and asexual thrips lineages in natural populations and under seminatural mesocosm conditions by varying the number of hostplants available to these herbivorous insects. Asexual lineages rapidly replaced the sexual ones, independently of the level of habitat heterogeneity in mesocosms. In natural populations, the success of sexual thrips decreased with increasing habitat heterogeneity, with sexual thrips apparently only persisting in certain types of hostplant communities. Our results illustrate how genetic diversity‐based mechanisms can favor asexuality instead of sex when sexual lineages co‐occur with genetically variable asexual lineages. PMID:27346066

Consequences of Asexuality in Natural Populations: Insights from Stick Insects.

PubMed

Bast, Jens; Parker, Darren J; Dumas, Zoé; Jalvingh, Kirsten M; Tran Van, Patrick; Jaron, Kamil S; Figuet, Emeric; Brandt, Alexander; Galtier, Nicolas; Schwander, Tanja

2018-07-01

Recombination is a fundamental process with significant impacts on genome evolution. Predicted consequences of the loss of recombination include a reduced effectiveness of selection, changes in the amount of neutral polymorphisms segregating in populations, and an arrest of GC-biased gene conversion. Although these consequences are empirically well documented for nonrecombining genome portions, it remains largely unknown if they extend to the whole genome scale in asexual organisms. We identify the consequences of asexuality using de novo transcriptomes of five independently derived, obligately asexual lineages of stick insects, and their sexual sister-species. We find strong evidence for higher rates of deleterious mutation accumulation, lower levels of segregating polymorphisms and arrested GC-biased gene conversion in asexuals as compared with sexuals. Taken together, our study conclusively shows that predicted consequences of genome evolution under asexuality can indeed be found in natural populations.

Biological markers of asexuality: Handedness, birth order, and finger length ratios in self-identified asexual men and women.

PubMed

Yule, Morag A; Brotto, Lori A; Gorzalka, Boris B

2014-02-01

Human asexuality is defined as a lack of sexual attraction to anyone or anything and it has been suggested that it may be best conceptualized as a sexual orientation. Non-right-handedness, fraternal birth order, and finger length ratio (2D:4D) are early neurodevelopmental markers associated with sexual orientation. We conducted an Internet study investigating the relationship between self-identification as asexual, handedness, number of older siblings, and self-measured finger-lengths in comparison to individuals of other sexual orientation groups. A total of 325 asexuals (60 men and 265 women; M age, 24.8 years), 690 heterosexuals (190 men and 500 women; M age, 23.5 years), and 268 non-heterosexuals (homosexual and bisexual; 64 men and 204 women; M age, 29.0 years) completed online questionnaires. Asexual men and women were 2.4 and 2.5 times, respectively, more likely to be non-right-handed than their heterosexual counterparts and there were significant differences between sexual orientation groups in number of older brothers and older sisters, and this depended on handedness. Asexual and non-heterosexual men were more likely to be later-born than heterosexual men, and asexual women were more likely to be earlier-born than non-heterosexual women. We found no significant differences between sexual orientation groups on measurements of 2D:4D ratio. This is one of the first studies to test and provide preliminary empirical support for an underlying neurodevelopmental basis to account for the lack of sexual attraction characteristic of asexuality.

Use of an acoustic helium analyzer for measuring lung volumes.

PubMed

Krumpe, P E; MacDannald, H J; Finley, T N; Schear, H E; Hall, J; Cribbs, D

1981-01-01

We have evaluated the use of an acoustic gas analyzer (AGA) for the measurement of total lung capacity (TLC) by single-breath helium dilution. The AGA has a rapid response time (0-90% response = 160 ms for 10% He), is linear for helium concentration of 0.1-10%, is stable over a wide range of ambient temperatures, and is small and portable. We plotted the output of the AGA vs. expired lung volume after a vital capacity breath of 10% He. However, since the AGA is sensitive to changes in speed of sound relative to air, the AGA output signal also reports an artifact due to alveolar gases. We corrected for this artifact by replotting a single-breath expiration after a vital capacity breath of room air. Mean alveolar helium concentration (HeA) was then measured by planimetry, using this alveolar gas curve as the base line. TLC was calculated using the HeA from the corrected AGA output and compared with TLC calculated from HeA simultaneously measured using a mass spectrometer (MS). In 12 normal subjects and 9 patients with chronic obstructive pulmonary disease (COPD) TLC-AGA and TLC-MS were compared by linear regression analysis; correlation coefficient (r) was 0.973 for normals and 0.968 for COPD patients (P less than 0.001). This single-breath; estimation of TLC using the corrected signal of the AGA vs. Expired volume seems ideally suited for the measurement of subdivisions of lung volume in field studies.

IgM ganglioside GM1 antibodies in patients with autoimmune disease or neuropathy, and controls.

PubMed Central

Bansal, A S; Abdul-Karim, B; Malik, R A; Goulding, P; Pumphrey, R S; Boulton, A J; Holt, P L; Wilson, P B

1994-01-01

AIMS--To compare the titre of anti-ganglioside antibodies (AGA) to GM1 ganglioside in patients with central and peripheral neurological disease and pure motor and sensorimotor neuropathy, in patients with classic autoimmune diseases, and controls. METHODS--AGA to GM1 were measured using an enzyme linked immunosorbent assay (ELISA) technique, highly purified bovine GM1 ganglioside, and sequential dilution of control and test sera. Antibody titre was calculated using the optical density readings of three consecutive serum dilutions multiplied by the dilution factor. RESULTS--A considerable overlap was evident in the titre of AGA to GM1 in control and test sera. High antibody titres were most frequent in patients with multifocal motor neuropathy with conduction block (MMNCB). Low AGA titre were observed in several patient groups. Compared with the controls, the median titre of AGA to GM1 was significantly higher in patients with multiple sclerosis, rheumatoid arthritis, primary Sjögren's syndrome and systemic lupus erythematosus. In contrast, the median titre in patients with diabetic peripheral neuropathy, motor neurone disease, sensorimotor neuropathy and chronic inflammatory demyelinating polyneuropathy was no different from that in normal control subjects. CONCLUSIONS--Estimation of AGA to GM1 may be helpful in the diagnosis of MMNCB in patients with a pure motor neuropathy but in few other conditions. Low titre AGA to GM1 are evident in several autoimmune conditions. The pathogenetic importance of AGA to GM1 in patients with neuropathy is not clear. PMID:8027366

Ribosome stalling and peptidyl-tRNA drop-off during translational delay at AGA codons

PubMed Central

Cruz-Vera, Luis Rogelio; Magos-Castro, Marco Antonio; Zamora-Romo, Efraín; Guarneros, Gabriel

2004-01-01

Minigenes encoding the peptide Met–Arg–Arg have been used to study the mechanism of toxicity of AGA codons proximal to the start codon or prior to the termination codon in bacteria. The codon sequences of the ‘mini-ORFs’ employed were initiator, combinations of AGA and CGA, and terminator. Both, AGA and CGA are low-usage Arg codons in ORFs of Escherichia coli but, whilst AGA is translated by the scarce tRNAArg4, CGA is recognized by the abundant tRNAArg2. Overexpression of minigenes harbouring AGA in the third position, next to a termination codon, was deleterious to the cell and led to the accumulation of peptidyl-tRNAArg4 and of the peptidyl-tRNA cognate to the preceding CGA or AGA Arg triplet. The minigenes carrying CGA in the third position were not toxic. Minigene-mediated toxicity and peptidyl-tRNA accumulation were suppressed by overproduction of tRNAArg4 but not by overproduction of peptidyl-tRNA hydrolase, an enzyme that is only active on substrates that have been released from the ribosome. Consistent with these findings, peptidyl-tRNAArg4 was identified to be mainly associated with ribosomes in a stand-by complex. These and previous results support the hypothesis that the primary mechanism of inhibition of protein synthesis by AGA triplets in pth+ cells involves sequestration of tRNAs as peptidyl-tRNA on the stalled ribosome. PMID:15317870

The dynamics of adapting, unregulated populations and a modified fundamental theorem.

PubMed

O'Dwyer, James P

2013-01-06

A population in a novel environment will accumulate adaptive mutations over time, and the dynamics of this process depend on the underlying fitness landscape: the fitness of and mutational distance between possible genotypes in the population. Despite its fundamental importance for understanding the evolution of a population, inferring this landscape from empirical data has been problematic. We develop a theoretical framework to describe the adaptation of a stochastic, asexual, unregulated, polymorphic population undergoing beneficial, neutral and deleterious mutations on a correlated fitness landscape. We generate quantitative predictions for the change in the mean fitness and within-population variance in fitness over time, and find a simple, analytical relationship between the distribution of fitness effects arising from a single mutation, and the change in mean population fitness over time: a variant of Fisher's 'fundamental theorem' which explicitly depends on the form of the landscape. Our framework can therefore be thought of in three ways: (i) as a set of theoretical predictions for adaptation in an exponentially growing phase, with applications in pathogen populations, tumours or other unregulated populations; (ii) as an analytically tractable problem to potentially guide theoretical analysis of regulated populations; and (iii) as a basis for developing empirical methods to infer general features of a fitness landscape.

Loss of sexual recombination and segregation is associated with increased diversification in evening primroses.

PubMed

Johnson, Marc T J; Fitzjohn, Richard G; Smith, Stacey D; Rausher, Mark D; Otto, Sarah P

2011-11-01

The loss of sexual recombination and segregation in asexual organisms has been portrayed as an irreversible process that commits asexually reproducing lineages to reduced diversification. We test this hypothesis by estimating rates of speciation, extinction, and transition between sexuality and functional asexuality in the evening primroses. Specifically, we estimate these rates using the recently developed BiSSE (Binary State Speciation and Extinction) phylogenetic comparative method, which employs maximum likelihood and Bayesian techniques. We infer that net diversification rates (speciation minus extinction) in functionally asexual evening primrose lineages are roughly eight times faster than diversification rates in sexual lineages, largely due to higher speciation rates in asexual lineages. We further reject the hypothesis that a loss of recombination and segregation is irreversible because the transition rate from functional asexuality to sexuality is significantly greater than zero and in fact exceeded the reverse rate. These results provide the first empirical evidence in support of the alternative theoretical prediction that asexual populations should instead diversify more rapidly than sexual populations because they are free from the homogenizing effects of sexual recombination and segregation. Although asexual reproduction may often constrain adaptive evolution, our results show that the loss of recombination and segregation need not be an evolutionary dead end in terms of diversification of lineages. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

Origin, divergence, and phylogeny of asexual Epichloë endophyte in Elymus species from western China.

PubMed

Song, Hui; Nan, Zhibiao

2015-01-01

Asexual Epichloë species are likely derived directly from sexual Epichloë species that then lost their capacity for sexual reproduction or lost sexual reproduction because of interspecific hybridization between distinct lineages of sexual Epichloë and/or asexual Epichloë species. In this study we isolated asexual Epichloë endophytes from Elymus species in western China and sequenced intron-rich regions in the genes encoding β-tubulin (tubB) and translation elongation factor 1-α (tefA). Our results showed that there are no gene copies of tubB and tefA in any of the isolates. Phylogenetic analysis showed that sequences in this study formed a single clade with asexual Epichloë bromicola from Hordeum brevisubulatum, which implies asexual Epichloë endophytes that are symbionts in a western Chinese Elymus species likely share a common ancestor with asexual E. bromicola from European H. brevisubulatum. In addition, our results revealed that asexual E. bromicola isolates that are symbionts in a western Chinese Elymus species and sexual Epichloë species that are symbionts in a North American Elymus species have a different origin. Further analysis found that Epichloë species likely originated in Eurasia. In addition, the results support the hypothesis that migratory birds or humans might have aided the dispersal of these fungal endophytes to other continents.

Origin, Divergence, and Phylogeny of Asexual Epichloë Endophyte in Elymus Species from Western China

PubMed Central

Song, Hui; Nan, Zhibiao

2015-01-01

Asexual Epichloë species are likely derived directly from sexual Epichloë species that then lost their capacity for sexual reproduction or lost sexual reproduction because of interspecific hybridization between distinct lineages of sexual Epichloë and/or asexual Epichloë species. In this study we isolated asexual Epichloë endophytes from Elymus species in western China and sequenced intron-rich regions in the genes encoding β-tubulin (tubB) and translation elongation factor 1-α (tefA). Our results showed that there are no gene copies of tubB and tefA in any of the isolates. Phylogenetic analysis showed that sequences in this study formed a single clade with asexual Epichloë bromicola from Hordeum brevisubulatum, which implies asexual Epichloë endophytes that are symbionts in a western Chinese Elymus species likely share a common ancestor with asexual E. bromicola from European H. brevisubulatum. In addition, our results revealed that asexual E. bromicola isolates that are symbionts in a western Chinese Elymus species and sexual Epichloë species that are symbionts in a North American Elymus species have a different origin. Further analysis found that Epichloë species likely originated in Eurasia. In addition, the results support the hypothesis that migratory birds or humans might have aided the dispersal of these fungal endophytes to other continents. PMID:25970178

Exact solutions for the selection-mutation equilibrium in the Crow-Kimura evolutionary model.

PubMed

Semenov, Yuri S; Novozhilov, Artem S

2015-08-01

We reformulate the eigenvalue problem for the selection-mutation equilibrium distribution in the case of a haploid asexually reproduced population in the form of an equation for an unknown probability generating function of this distribution. The special form of this equation in the infinite sequence limit allows us to obtain analytically the steady state distributions for a number of particular cases of the fitness landscape. The general approach is illustrated by examples; theoretical findings are compared with numerical calculations. Copyright © 2015. Published by Elsevier Inc.

Multi-therapies in androgenetic alopecia: review and clinical experiences.

PubMed

Rossi, Alfredo; Anzalone, Alessia; Fortuna, Maria Caterina; Caro, Gemma; Garelli, Valentina; Pranteda, Giulia; Carlesimo, Marta

2016-11-01

Androgenetic alopecia (AGA) is a genetically determined progressive hair-loss condition which represents the most common cause of hair loss in men. The use of the medical term androgenetic alopecia reflects current knowledge about the important role of androgens and genetic factors in its etiology. In addition to androgen-dependent changes in the hair cycle, sustained microscopic follicular inflammation contributes to its onset. Furthermore, Prostaglandins have been demonstrated to have the ability in modulating hair follicle cycle; in particular, PGD2 inhibits hair growth while PGE2/F2a promote growth. Due to the progressive nature of AGA, the treatment should be started early and continued indefinitely, since the benefit will not be maintained upon ceasing therapy. To date, only two therapeutic agents have been approved by the Food and Drug Administration and European Medicines Agency for the treatment of AGA: topical minoxidil and oral finasteride. Considering the many pathogenetic mechanisms involved in AGA, various treatment options are available: topical and systemic drugs may be used and the choice depends on various factors including grading of AGA, patients' pathological conditions, practicability, costs and risks. So, the treatment for AGA should be based on personalized therapy and targeted at the different pathophysiological aspects of AGA. © 2016 Wiley Periodicals, Inc.

Dispersal and life history strategies in epiphyte metacommunities: alternative solutions to survival in patchy, dynamic landscapes.

PubMed

Löbel, Swantje; Rydin, Håkan

2009-09-01

Host trees for obligate epiphytes are dynamic patches that emerge, grow and fall, and metacommunity diversity critically depends on efficient dispersal. Even though species that disperse by large asexual diaspores are strongly dispersal limited, asexual dispersal is common. The stronger dispersal limitation of asexually reproducing species compared to species reproducing sexually via small spores may be compensated by higher growth rates, lower sensitivity to habitat conditions, higher competitive ability or younger reproductive age. We compared growth and reproduction of different groups of epiphytic bryophytes with contrasting dispersal (asexual vs. sexual) and life history strategies (colonists, short- and long-lived shuttle species, perennial stayers) in an old-growth forest stand in the boreo-nemoral region in eastern Sweden. No differences were seen in relative growth rates between asexual and sexual species. Long-lived shuttles had lower growth rates than colonists and perennial stayers. Most groups grew best at intermediate bark pH. Interactions with other epiphytes had a small, often positive effect on growth. Neither differences in sensitivity of growth to habitat conditions nor differences in competitive abilities among species groups were found. Habitat conditions, however, influenced the production of sporophytes, but not of asexual diaspores. Presence of sporophytes negatively affected growth, whereas presence of asexual diaspores did not. Sexual species had to reach a certain colony size before starting to reproduce, whereas no such threshold existed for asexual reproduction. The results indicate that the epiphyte metacommunity is structured by two main trade-offs: dispersal distance vs. reproductive age, and dispersal distance vs. sensitivity to habitat quality. There seems to be a trade-off between growth and sexual reproduction, but not asexual. Trade-offs in species traits may be shaped by conflicting selection pressures imposed by habitat turnover and connectivity rather than by species interactions.

Second Generation Multi-Gas Monitor for ISS and Orion: The Anomaly Gas Analyzer

NASA Technical Reports Server (NTRS)

Mudgett, Paul D.; Coan, Mary R.; Limero, Thomas; Pilgrim, Jeffrey S.

2017-01-01

First flight of AGA on Orion First flight of AGA on ISS Because of high reliability and long calibration interval, we recommend TDLS based monitors be considered for submarines Sea trials of AGA would be a logical follow-on to the MGM sea trial that is currently underway.

Digit-Length Ratios (2D:4D) as a Phenotypic Indicator of in Utero Androgen Exposure is Not Prognostic for Androgenic Alopecia: a Descriptive-Analytic Study of 1200 Iranian Men.

PubMed

Feily, Amir; Hosseinpoor, Masoomeh; Bakhti, Ali; Nekuyi, Mohamad; Sobhanian, Saeed; Fathinezhad, Zahra; Sahraei, Reza; Ramirez-Fort, Marigdalia K

2016-06-15

The etiology of androgenic alopecia (AGA) involves several factors, including genetics, androgens, age and nutrition. Digit-length ratio of the index and ring finger (2D:4D) is an indicator of prenatal exposure to sex hormones. There is a paucity of studies that systemically review the possible positive predictive value of 2D:4D in the development of AGA. We performed a single-site, descriptive-analytical study among a racially homogeneous population. Our results revealed that no significant association was determined between right 2D:4D and AGA severity within our entire population (P=0.384, r=0.025), however a positive correlation coefficient was identified in subjects above the age of 40. Based on the receiver operating characteristic curve analysis, 2D:4D does not predict the development of AGA. AGA is truly a multifactorial disease. Further, our findings suggest that increased in utero exposure to androgens as a fetus does not predispose men to develop AGA.

Isolation and Characterization of a Glycosyl Hydrolase Family 16 β-Agarase from a Mangrove Soil Metagenomic Library

PubMed Central

Mai, Zhimao; Su, Hongfei; Zhang, Si

2016-01-01

A mangrove soil metagenomic library was constructed and a β-agarase gene designated as AgaML was isolated by functional screening. The gene encoded for a 659-amino-acids polypeptide with an estimated molecular mass of 71.6 kDa. The deduced polypeptide sequences of AgaML showed the highest identity of 73% with the glycoside hydrolase family 16 β-agarase from Microbulbifer agarilyticus in the GenBank database. AgaML was cloned and highly expressed in Escherichia coli BL21(DE3). The purified recombinant protein, AgaML, showed optimal activity at 50 °C and pH 7.0. The kinetic parameters of Km and Vmax values toward agarose were 4.6 mg·mL−1 and 967.5 μM·min−1·mg−1, respectively. AgaML hydrolyzed the β-1,4-glycosidic linkages of agar to generate neoagarotetraose (NA4) and neoagarohexaose (NA6) as the main products. These characteristics suggest that AgaML has potential application in cosmetic, pharmaceuticals and food industries. PMID:27548158

Bioactives in Chinese Proprietary Medicine Modulates 5α-Reductase Activity and Gene Expression Associated with Androgenetic Alopecia

PubMed Central

Tan, Justin J. Y.; Pan, Jing; Sun, Lihan; Zhang, Junying; Wu, Chunyong; Kang, Lifeng

2017-01-01

Androgenetic alopecia (AGA) is characterized by a progressive and patterned transformation of thick, pigmented terminal scalp hairs into short, hypo-pigmented vellus-like hairs. The use of Minoxidil and Finasteride to treat AGA are often associated with complications in safety and efficacy. However, herbal remedies are deemed to have lesser side effects in many societies. This study aims to identify potential hair growth properties of individual compounds from a Chinese proprietary medicine known as Yangxue Shengfa capsule (YSC), used in China for many years for improving AGA. Six marker compounds, including 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside (TSG), Chlorogenic acid, Emodin, Ferulic acid, Isoimperatorin, and Paeoniflorin were used for simultaneous HPLC quantification and anti-AGA in-vitro screening. Simultaneous quantification of these components was performed on 75% (v/v) methanol extracts of YSC, using a Welch Ultimate XB-C18 column and gradient elution. Five compounds significantly promoted cell proliferation in cultured immortalized human Dermal Papilla Cells (DPC). Multiple genes associated with the progression of AGA, including IGF-1, DKK-1, and TGF-β1, were found to be regulated by some of these compounds. Interestingly, Ferulic acid and Emodin demonstrated good pharmacological properties against AGA, thereby concluding the potential of these bioactives to be used in the treatment against AGA. PMID:28450835

Sexual conflict and the evolution of asexuality at low population densities.

PubMed

Gerber, Nina; Kokko, Hanna

2016-10-26

Theories for the evolution of sex rarely include facultatively sexual reproduction. Sexual harassment by males is an underappreciated factor: it should at first sight increase the relative advantage of asexual reproduction by increasing the cost of sex. However, if the same females can perform either sexual or asexual life cycles, then females trying to reproduce asexually may not escape harassment. If resisting male harassment is costly, it might be beneficial for a female to accept a mating and undertake a sexual life cycle rather than 'insist' on an asexual one. We investigate the effects of sexual harassment on the maintenance of sex under different population densities. Our model shows that resisting matings pays off at low population densities, which leads to the complete extinction of males, and thus to the evolution of completely asexual populations. Facultative sex persists in a narrow range of slightly higher densities. At high densities, selection favours giving up resisting male mating attempts and thus sexual reproduction takes over. These interactions between the outcomes of sexual conflict and population density suggest an explanation for the rarity of facultative sex and also patterns of geographical parthenogenesis, where marginal environments with potentially low densities are associated with asexuality. © 2016 The Author(s).

Comparison of Natural Gas Storage Estimates from the EIA and AGA

EIA Publications

1997-01-01

The Energy Information Administration (EIA) has been publishing monthly storage information for years. In order to address the need for more timely information, in 1994 the American Gas Association (AGA) began publishing weekly storage levels. Both the EIA and the AGA series provide estimates of the total working gas in storage, but use significantly different methodologies.

[Effects of electro-acupuncture on expression of triggering receptor expressed on myeloid cells 1 in ankle joint synovial tissue of acute gouty arthritis rats].

PubMed

Zhang, Chao-Nan; Huang, Xue-Kuan; Luo, Yan; Jiang, Juan; Wan, Lei; Wang, Ling

2015-01-01

To investigate the effects of electro-acupuncture (EA) on the expression of triggering receptor expressed on myeloid cell (TREM)l in ankle joint synovial tissue of acute gouty arthritis (AGA) rats. Forty male SD rats were randomly divided into 4 groups: normal, AGA, medication and EA group, 10 rats in each group. AGA model was established by induced monosodium urate (MSU) method, except the normal group. Tow days before AGA model was established, normal and AGA groups were lavaged with normal saline (20 ml/kg), medication group was lavaged with colchicine solution (20 ml/kg), EA(1.5-2 Hz, D.-D.wave, 9v; 1-3 rnA) was applied to "Sanyinjiao" (SP6), "jiexi" (ST41) and "Kunlun" (BL60) for 20 min, once daily;continuously for 9 days. Then observed the changes in dysfunction, and the content of TNF-α and IL-lβ detected by ELISA, the expression of TREM-l detected by immunohistochemistry and western blot. Compared to the normal group, the AGA group of the dysfunction index increased significantly (P<0.01), the content of TNF-α and IL-lβ increased significantly (P<0.05), the expression of TREM-l in synovial tissue increased significantly (P<0.05); the medication and EA groups compared to the AGA group, the dysfunction index decreased significantly (P<0.01), the content of TNF-α and IL-lβ decreased significantly (P<0.05), the expression of TREM-l in synovial tissue decreased significantly (P<0.05); there were not statistically significant between the medication and EA group (P>0.05). EA treating AGA may be through down-regulating the expression of TREM -1 in synovial tissue.

Ghrelin and obestatin plasma levels and ghrelin/obestatin prepropeptide gene polymorphisms in small for gestational age infants.

PubMed

Zhang, Shulian; Zhai, Guanpeng; Zhang, Jinping; Zhou, Jianguo; Chen, Chao

2014-12-01

To investigate plasma ghrelin and obestatin levels, and ghrelin/obestatin prepropeptide gene polymorphisms, in sequentially enrolled small for gestational age (SGA) infants. Neonates were sequentially enrolled into this study and were then subdivided into different groups, according to different study aims and availability of study materials. Consequently, plasma ghrelin and obestatin levels were measured in term SGA, term appropriate for gestational age (AGA), term large for gestational age (LGA), preterm SGA and preterm AGA neonates. Levels of both peptides were also measured in AGA infants of different gestational ages, and in term AGA neonates at different days following birth. Three ghrelin/obestatin prepropeptide gene single nucleotide polymorphisms (SNPs), Arg51Gln, Leu72Met, and Gln90Leu, were measured in neonates. The study involved a total cohort of 581 neonates. Out of 150 neonates (30 term AGA, 30 term SGA, 30 term LGA, 30 preterm AGA, and 30 preterm SGA), plasma obestatin levels were significantly higher in term SGA versus term LGA neonates (0.21 ± 0.02 ng/ml versus 0.17 ± 0.01 ng/ml, respectively). Out of a wider cohort, there were no significant differences in genotypes and allele frequencies of Arg51Gln, Leu72Met, and Gln90Leu SNPs between term SGA and AGA neonates, or between preterm SGA and AGA neonates. Ghrelin/obestatin prepropeptide polymorphisms were not found to be associated with SGA status in neonates; however, ghrelin and obestatin levels may be involved in growth and development. Further studies are required to understand the relationship between ghrelin, obestatin and prenatal development. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Analyses between Reproductive Behavior, Genetic Diversity and Pythium Responsiveness in Zingiber spp. Reveal an Adaptive Significance for Hemiclonality

PubMed Central

Thomas, Geethu E.; Geetha, Kiran A.; Augustine, Lesly; Mamiyil, Sabu; Thomas, George

2016-01-01

Mode of reproduction is generally considered to have long-range evolutionary implications on population survival. Because sexual reproduction produces genetically diverse genotypes, this mode of reproduction is predicted to positively influence the success potential of offspring in evolutionary arms race with parasites (Red queen) whereas, without segregation and recombination, the obligate asexual multiplication may push a species into extinction due to the steady accumulation of deleterious mutations (Muller’s ratchet). However, the extent of linearity between reproductive strategies, genetic diversity and population fitness, and the contributions of different breeding strategies to population fitness are yet to be understood clearly. Genus Zingiber belonging to the pan-tropic family Zingiberaceae represents a good system to study contributions of different breeding behavior on genetic diversity and population fitness, as this genus comprises species with contrasting breeding systems. In this study, we analyzed breeding behavior, amplified fragment length polymorphism diversity and response to the soft-rot pathogen Pythium aphanidermatum in 18 natural populations of three wild Zingiber spp.: Z. neesanum, Z. nimmonii, and Z. zerumbet, together with the obligately asexual cultivated congener, ginger (Z. officinale). Ginger showed an exceptionally narrow genetic base, and adding to this, all the tested cultivars were uniformly susceptible to soft-rot. Concordant with the postulates of Muller’s ratchet, the background selection may be continuously pushing ginger into the ancestral state, rendering it inefficient in host-pathogen coevolution. Z. neesanum and Z. nimmonii populations were sexual and genetically diverse; however, contrary to Red Queen expectations, the populations were highly susceptible to soft-rot. Z. zerumbet showed a hemiclonal breeding behavior. The populations inhabiting forest understory were large and continuous, sexual and genetically diverse, but were susceptible, whereas populations inhabiting the revenue land were fragmented and monoclonal, but were resistant. It may be possible that, when genetic recombination becomes at a premium due to the genetic constraints imparted by habitat fragmentation or pathogen pressure, Z. zerumbet PMID:28066470

Coalescence with Background and Balancing Selection in Systems with Bi- and Uniparental Reproduction: Contrasting Partial Asexuality and Selfing

PubMed Central

Agrawal, Aneil F.; Hartfield, Matthew

2016-01-01

Uniparental reproduction in diploids, via asexual reproduction or selfing, reduces the independence with which separate loci are transmitted across generations. This is expected to increase the extent to which a neutral marker is affected by selection elsewhere in the genome. Such effects have previously been quantified in coalescent models involving selfing. Here we examine the effects of background selection and balancing selection in diploids capable of both sexual and asexual reproduction (i.e., partial asexuality). We find that the effect of background selection on reducing coalescent time (and effective population size) can be orders of magnitude greater when rates of sex are low than when sex is common. This is because asexuality enhances the effects of background selection through both a recombination effect and a segregation effect. We show that there are several reasons that the strength of background selection differs between systems with partial asexuality and those with comparable levels of uniparental reproduction via selfing. Expectations for reductions in Ne via background selection have been verified using stochastic simulations. In contrast to background selection, balancing selection increases the coalescence time for a linked neutral site. With partial asexuality, the effect of balancing selection is somewhat dependent upon the mode of selection (e.g., heterozygote advantage vs. negative frequency-dependent selection) in a manner that does not apply to selfing. This is because the frequency of heterozygotes, which are required for recombination onto alternative genetic backgrounds, is more dependent on the pattern of selection with partial asexuality than with selfing. PMID:26584901

Coalescence with Background and Balancing Selection in Systems with Bi- and Uniparental Reproduction: Contrasting Partial Asexuality and Selfing.

PubMed

Agrawal, Aneil F; Hartfield, Matthew

2016-01-01

Uniparental reproduction in diploids, via asexual reproduction or selfing, reduces the independence with which separate loci are transmitted across generations. This is expected to increase the extent to which a neutral marker is affected by selection elsewhere in the genome. Such effects have previously been quantified in coalescent models involving selfing. Here we examine the effects of background selection and balancing selection in diploids capable of both sexual and asexual reproduction (i.e., partial asexuality). We find that the effect of background selection on reducing coalescent time (and effective population size) can be orders of magnitude greater when rates of sex are low than when sex is common. This is because asexuality enhances the effects of background selection through both a recombination effect and a segregation effect. We show that there are several reasons that the strength of background selection differs between systems with partial asexuality and those with comparable levels of uniparental reproduction via selfing. Expectations for reductions in Ne via background selection have been verified using stochastic simulations. In contrast to background selection, balancing selection increases the coalescence time for a linked neutral site. With partial asexuality, the effect of balancing selection is somewhat dependent upon the mode of selection (e.g., heterozygote advantage vs. negative frequency-dependent selection) in a manner that does not apply to selfing. This is because the frequency of heterozygotes, which are required for recombination onto alternative genetic backgrounds, is more dependent on the pattern of selection with partial asexuality than with selfing. Copyright © 2016 by the Genetics Society of America.

A Perspective on the Importance of Reproductive Mode in Astrobiology

NASA Astrophysics Data System (ADS)

Van Doninck, Karine; Schön, Isa; Martens, Koen

2003-12-01

Reproduction is a vital characteristic of life, and sex is the most common reproductive mode in the eukaryotic world. Sex and reproduction are not necessarily linked mechanisms: Sexuality without reproduction exists, while several forms of asexual reproduction are known. The occurrence of sexuality itself is paradoxical, as it is very costly in evolutionary terms. Most of the hypotheses (more than 20) attempting to explain the prevalence of sex fall into two categories: Sex either creates good gene combinations for adaptation to environments or eliminates bad gene combinations counteracting the accumulation of mutations. In spite of this apparent wealth of beneficial effects of sex, asexuality is not rare. Most eukaryotic, asexual lineages are short-lived and can only persist through the presence of sexual roots, but at least two animal groups, bdelloid rotifers and darwinulid ostracods, seem to claim the status of ancient asexuals. Research on (a)sexuality is relevant to astrobiology in a number of ways. First, strong relationships between the origin and persistence of life in extreme environments and reproductive mode are known. Second, the "habitability" of nonterrestrial environments to life greatly depends on reproductive mode. Whereas asexuals can do equally well or better in harsh environments, they fail to adapt fast enough to changing abiotic and biotic environments. Third, it has been shown that plants reproduce mainly asexually in space, and sperm production and motility in some vertebrates are hampered. Both findings indicate that extraterrestrial life under conditions different from Earth might be dominated by asexual reproduction. Finally, for exchange of biological material between planets, the choice of reproductive mode will be important.

Asexual Reproduction Does Not Apparently Increase the Rate of Chromosomal Evolution: Karyotype Stability in Diploid and Triploid Clonal Hybrid Fish (Cobitis, Cypriniformes, Teleostei)

PubMed Central

Majtánová, Zuzana; Choleva, Lukáš; Symonová, Radka; Ráb, Petr; Kotusz, Jan; Pekárik, Ladislav; Janko, Karel

2016-01-01

Interspecific hybridization, polyploidization and transitions from sexuality to asexuality considerably affect organismal genomes. Especially the last mentioned process has been assumed to play a significant role in the initiation of chromosomal rearrangements, causing increased rates of karyotype evolution. We used cytogenetic analysis and molecular dating of cladogenetic events to compare the rate of changes of chromosome morphology and karyotype in asexually and sexually reproducing counterparts in European spined loach fish (Cobitis). We studied metaphases of three sexually reproducing species and their diploid and polyploid hybrid clones of different age of origin. The material includes artificial F1 hybrid strains, representatives of lineage originated in Holocene epoch, and also individuals of an oldest known age to date (roughly 0.37 MYA). Thereafter we applied GISH technique as a marker to differentiate parental chromosomal sets in hybrids. Although the sexual species accumulated remarkable chromosomal rearrangements after their speciation, we observed no differences in chromosome numbers and/or morphology among karyotypes of asexual hybrids. These hybrids possess chromosome sets originating from respective parental species with no cytogenetically detectable recombinations, suggesting their integrity even in a long term. The switch to asexual reproduction thus did not provoke any significant acceleration of the rate of chromosomal evolution in Cobitis. Asexual animals described in other case studies reproduce ameiotically, while Cobitis hybrids described here produce eggs likely through modified meiosis. Therefore, our findings indicate that the effect of asexuality on the rate of chromosomal change may be context-dependent rather than universal and related to particular type of asexual reproduction. PMID:26808475

Asexual Reproduction Does Not Apparently Increase the Rate of Chromosomal Evolution: Karyotype Stability in Diploid and Triploid Clonal Hybrid Fish (Cobitis, Cypriniformes, Teleostei).

PubMed

Majtánová, Zuzana; Choleva, Lukáš; Symonová, Radka; Ráb, Petr; Kotusz, Jan; Pekárik, Ladislav; Janko, Karel

2016-01-01

Interspecific hybridization, polyploidization and transitions from sexuality to asexuality considerably affect organismal genomes. Especially the last mentioned process has been assumed to play a significant role in the initiation of chromosomal rearrangements, causing increased rates of karyotype evolution. We used cytogenetic analysis and molecular dating of cladogenetic events to compare the rate of changes of chromosome morphology and karyotype in asexually and sexually reproducing counterparts in European spined loach fish (Cobitis). We studied metaphases of three sexually reproducing species and their diploid and polyploid hybrid clones of different age of origin. The material includes artificial F1 hybrid strains, representatives of lineage originated in Holocene epoch, and also individuals of an oldest known age to date (roughly 0.37 MYA). Thereafter we applied GISH technique as a marker to differentiate parental chromosomal sets in hybrids. Although the sexual species accumulated remarkable chromosomal rearrangements after their speciation, we observed no differences in chromosome numbers and/or morphology among karyotypes of asexual hybrids. These hybrids possess chromosome sets originating from respective parental species with no cytogenetically detectable recombinations, suggesting their integrity even in a long term. The switch to asexual reproduction thus did not provoke any significant acceleration of the rate of chromosomal evolution in Cobitis. Asexual animals described in other case studies reproduce ameiotically, while Cobitis hybrids described here produce eggs likely through modified meiosis. Therefore, our findings indicate that the effect of asexuality on the rate of chromosomal change may be context-dependent rather than universal and related to particular type of asexual reproduction.

A little bit of sex matters for genome evolution in asexual plants.

PubMed

Hojsgaard, Diego; Hörandl, Elvira

2015-01-01

Genome evolution in asexual organisms is theoretically expected to be shaped by various factors: first, hybrid origin, and polyploidy confer a genomic constitution of highly heterozygous genotypes with multiple copies of genes; second, asexuality confers a lack of recombination and variation in populations, which reduces the efficiency of selection against deleterious mutations; hence, the accumulation of mutations and a gradual increase in mutational load (Muller's ratchet) would lead to rapid extinction of asexual lineages; third, allelic sequence divergence is expected to result in rapid divergence of lineages (Meselson effect). Recent transcriptome studies on the asexual polyploid complex Ranunculus auricomus using single-nucleotide polymorphisms confirmed neutral allelic sequence divergence within a short time frame, but rejected a hypothesis of a genome-wide accumulation of mutations in asexuals compared to sexuals, except for a few genes related to reproductive development. We discuss a general model that the observed incidence of facultative sexuality in plants may unmask deleterious mutations with partial dominance and expose them efficiently to purging selection. A little bit of sex may help to avoid genomic decay and extinction.

Molecular Markers to Detect the Formation of Heterokaryon and Homokaryon from Asexual Spores of the Caterpillar Medicinal Mushroom, Cordyceps militaris (Ascomycetes).

PubMed

Wang, Hong; Cai, Tao; Wei, Jing; Feng, Aiping; Lin, Nan; Bao, Dapeng

2015-01-01

Cordyceps militaris is widely cultivated on artificial media in China; however, the cultures often are afflicted with the degeneration of nonfruiting strains. To understand the mechanism of degeneration of C. militaris, from the heterokaryotic strain into the homokaryotic strain, we examined the mating-type genes present in individual asexual spores. Further, we determined the distribution ratio of the different mating-type genes among a sample of asexual spores and the growth rate of heterokaryotic and homokaryotic strains of C. militaris. The distribution ratio of 3 groups of asexual spores from C. militaris heterokaryotic strains was determined as 1:1:1 by statistical analysis, whereas that of the two types of nuclei among asexual spores was 1:1. Nearly two-thirds of the asexual spore isolates were homokaryon, which showed a growth speed similar to the heterokaryon. However, the homokaryon (bearing mating-type MAT-HMG) grew significantly faster at times compared with the heterokaryon. Therefore, the purity of the spawn was difficult to establish. C. militaris heterokaryotic strains can transform into a homokaryotic strain following continued subculture.

Sex drives intracellular conflict in yeast.

PubMed

Harrison, E; MacLean, R C; Koufopanou, V; Burt, A

2014-08-01

Theory predicts that sex can drive the evolution of conflict within the cell. During asexual reproduction, genetic material within the cell is inherited as a single unit, selecting for cooperation both within the genome as well as between the extra-genomic elements within the cell (e.g. plasmids and endosymbionts). Under sexual reproduction, this unity is broken down as parental genomes are distributed between meiotic progeny. Genetic elements able to transmit to more than 50% of meiotic progeny have a transmission advantage over the rest of the genome and are able to spread, even where they reduce the fitness of the individual as a whole. Sexual reproduction is therefore expected to drive the evolution of selfish genetic elements (SGEs). Here, we directly test this hypothesis by studying the evolution of two independent SGEs, the 2-μm plasmid and selfish mitochondria, in populations of Saccharomyces cerevisiae. Following 22 rounds of sexual reproduction, 2-μm copy number increased by approximately 13.2 (±5.6) copies per cell, whereas in asexual populations copy number decreased by approximately 5.1 (±1.5) copies per cell. Given that the burden imposed by this parasite increases with copy number, these results support the idea that sex drives the evolution of increased SGE virulence. Moreover, we found that mitochondria that are respiratory-deficient rapidly invaded sexual but not asexual populations, demonstrating that frequent outcrossed sex can drive the de novo evolution of genetic parasites. Our study highlights the genomic perils of sex and suggests that SGEs may play a key role in driving major evolutionary transitions, such as uniparental inheritance. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Do the venous blood samples replicate malaria parasite densities found in capillary blood? A field study performed in naturally-infected asymptomatic children in Cameroon.

PubMed

Sandeu, Maurice M; Bayibéki, Albert N; Tchioffo, Majoline T; Abate, Luc; Gimonneau, Geoffrey; Awono-Ambéné, Parfait H; Nsango, Sandrine E; Diallo, Diadier; Berry, Antoine; Texier, Gaétan; Morlais, Isabelle

2017-08-17

The measure of new drug- or vaccine-based approaches for malaria control is based on direct membrane feeding assays (DMFAs) where gametocyte-infected blood samples are offered to mosquitoes through an artificial feeder system. Gametocyte donors are identified by the microscopic detection and quantification of malaria blood stages on blood films prepared using either capillary or venous blood. However, parasites are known to sequester in the microvasculature and this phenomenon may alter accurate detection of parasites in blood films. The blood source may then impact the success of mosquito feeding experiments and investigations are needed for the implementation of DMFAs under natural conditions. Thick blood smears were prepared from blood obtained from asymptomatic children attending primary schools in the vicinity of Mfou (Cameroon) over four transmission seasons. Parasite densities were determined microscopically from capillary and venous blood for 137 naturally-infected gametocyte carriers. The effect of the blood source on gametocyte and asexual stage densities was then assessed by fitting cumulative link mixed models (CLMM). DMFAs were performed to compare the infectiousness of gametocytes from the different blood sources to mosquitoes. Prevalence of Plasmodium falciparum asexual stages among asymptomatic children aged from 4 to 15 years was 51.8% (2116/4087). The overall prevalence of P. falciparum gametocyte carriage was 8.9% and varied from one school to another. No difference in the density of gametocyte and asexual stages was found between capillary and venous blood. Attempts to perform DMFAs with capillary blood failed. Plasmodium falciparum malaria parasite densities do not differ between capillary and venous blood in asymptomatic subjects for both gametocyte and trophozoite stages. This finding suggests that the blood source should not interfere with transmission efficiency in DMFAs.

Sexual versus Asexual Reproduction: Distinct Outcomes in Relative Abundance of Parthenogenetic Mealybugs following Recent Colonization.

PubMed

Tabata, Jun; Ichiki, Ryoko T; Tanaka, Hirotaka; Kageyama, Daisuke

2016-01-01

Asexual reproduction, including parthenogenesis in which embryos develop within a female without fertilization, is assumed to confer advantages over sexual reproduction, which includes a "cost of males." Sexual reproduction largely predominates in animals, however, indicating that this cost is outweighed by the genetic and/or ecological benefits of sexuality, including the acquisition of advantageous mutations occurring in different individuals and the elimination of deleterious mutations. But the evolution of sexual reproduction remains unclear, because we have limited examples that demonstrate the relative success of sexual lineages in the face of competition from asexual lineages in the same environment. Here we investigated a sympatric occurrence of sexual and asexual reproduction in the pineapple mealybug, Dysmicoccus brevipes. This pest invaded southwestern Japan, including Okinawa and Ishigaki Islands, in the 1930s in association with imported pineapple plants. Our recent censuses demonstrated that on Okinawa sexually reproducing individuals can coexist with and even dominate asexual individuals in the presence of habitat and resource competition, which is considered to be severe for this nearly immobile insect. Molecular phylogeny based on partial DNA sequences in the mitochondrial and nuclear genomes, as well as the endosymbiotic bacterial genome, revealed that the asexual lineage diverged from a common sexual ancestor in the relatively recent past. In contrast, only the asexual lineage exhibiting obligate apomictic thelytoky was discovered on Ishigaki. Co-existence of the two lineages cannot be explained by the results of laboratory experiments, which showed that the intrinsic rate of increase in the sexual lineage was not obviously superior to that of the asexual lineage. Differences in biotic and/or abiotic selective forces operating on the two islands might be the cause of this discrepancy. This biological system offers a unique opportunity to assess the relative success of sexual versus asexual lineages with an unusual morphology and life cycle.

Consequences of clonality for sexual fitness: Clonal expansion enhances fitness under spatially restricted dispersal.

PubMed

Van Drunen, Wendy E; van Kleunen, Mark; Dorken, Marcel E

2015-07-21

Clonality is a pervasive feature of sessile organisms, but this form of asexual reproduction is thought to interfere with sexual fitness via the movement of gametes among the modules that comprise the clone. This within-clone movement of gametes is expected to reduce sexual fitness via mate limitation of male reproductive success and, in some cases, via the production of highly inbred (i.e., self-fertilized) offspring. However, clonality also results in the spatial expansion of the genetic individual (i.e., genet), and this should decrease distances gametes and sexually produced offspring must travel to avoid competing with other gametes and offspring from the same clone. The extent to which any negative effects of clonality on mating success might be offset by the positive effects of spatial expansion is poorly understood. Here, we develop spatially explicit models in which fitness was determined by the success of genets through their male and female sex functions. Our results indicate that clonality serves to increase sexual fitness when it is associated with the outward expansion of the genet. Our models further reveal that the main fitness benefit of clonal expansion might occur through the dispersal of offspring over a wider area compared with nonclonal phenotypes. We conclude that, instead of interfering with sexual reproduction, clonal expansion should often serve to enhance sexual fitness.

A comparison of the metabolism of the abortifacient compounds from Ponderosa pine needles in conditioned versus naive cattle.

PubMed

Welch, K D; Gardner, D R; Pfister, J A; Panter, K E; Zieglar, J; Hall, J O

2012-12-01

Isocupressic acid (ICA) is the abortifacient compound in ponderosa pine (Pinus ponderosa L.) needles, which can cause late-term abortions in cattle (Bos taurus). However, cattle rapidly metabolize ICA to agathic acid (AGA) and subsequent metabolites. When pine needles are dosed orally to cattle, no ICA is detected in their serum, whereas AGA is readily detected. Recent research has demonstrated that AGA is also an abortifacient compound in cattle. The observation has been made that when cattle are dosed with labdane acids for an extended time, the concentration of AGA in serum increases for 1 to 2 d but then decreases to baseline after 5 to 6 d even though they are still being dosed twice daily. Therefore, in this study we investigated whether cattle conditioned to pine needles metabolize ICA, and its metabolites, faster than naïve cattle. Agathic acid was readily detected in the serum of naïve cattle fed ponderosa pine needles, whereas very little AGA was detected in the serum of cattle conditioned to pine needles. We also compared the metabolism of ICA in vitro using rumen cultures from pine-needle-conditioned and naïve cattle. In the rumen cultures from conditioned cattle, AGA concentrations were dramatically less than rumen cultures from naïve cattle. Thus, an adaptation occurs to cattle conditioned to pine needles such that the metabolism AGA by the rumen microflora is altered.

Ex-vivo assessment and non-invasive in vivo imaging of internal hemorrhages in Aga2/+ mutant mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ermolayev, Vladimir; Cohrs, Christian M.; Mohajerani, Pouyan

Highlights: ► Aga2/+ mice, model for Osteogenesis imperfecta, have type I collagen mutation. ► Aga2/+ mice display both moderate and severe phenotypes lethal 6–11th postnatal. ► Internal hemorrhages studied in Aga2/+ vs. control mice at 6 and 9 days postnatal. ► Anatomical and functional findings in-vivo contrasted to the ex-vivo appearance. -- Abstract: Mutations in type I collagen genes (COL1A1/2) typically lead to Osteogenesis imperfecta, the most common heritable cause of skeletal fractures and bone deformation in humans. Heterozygous Col1a1{sup Aga2/+}, animals with a dominant mutation in the terminal C-propeptide domain of type I collagen develop typical skeletal hallmarks andmore » internal hemorrhages starting from 6 day after birth. The disease progression for Aga2/+ mice, however, is not uniform differing between severe phenotype lethal at the 6–11th day of life, and moderate-to-severe one with survival to adulthood. Herein we investigated whether a new modality that combines X-ray computer tomography with fluorescence tomography in one hybrid system can be employed to study internal bleedings in relation to bone fractures and obtain insights into disease progression. The disease phenotype was characterized on Aga2/+ vs. wild type mice between 6 and 9 days postnatal. Anatomical and functional findings obtained in-vivo were contrasted to the ex-vivo appearance of the same tissues under cryo-slicing.« less

A mouse model of androgenetic alopecia.

PubMed

Crabtree, Judy S; Kilbourne, Edward J; Peano, Bryan J; Chippari, Susan; Kenney, Thomas; McNally, Christopher; Wang, Wei; Harris, Heather A; Winneker, Richard C; Nagpal, Sunil; Thompson, Catherine C

2010-05-01

Androgenetic alopecia (AGA), commonly known as male pattern baldness, is a form of hair loss that occurs in both males and females. Although the exact cause of AGA is not known, it is associated with genetic predisposition through traits related to androgen synthesis/metabolism and androgen signaling mediated by the androgen receptor (AR). Current therapies for AGA show limited efficacy and are often associated with undesirable side effects. A major hurdle to developing new therapies for AGA is the lack of small animal models to support drug discovery research. Here, we report the first rodent model of AGA. Previous work demonstrating that the interaction between androgen-bound AR and beta-catenin can inhibit Wnt signaling led us to test the hypothesis that expression of AR in hair follicle cells could interfere with hair growth in an androgen-dependent manner. Transgenic mice overexpressing human AR in the skin under control of the keratin 5 promoter were generated. Keratin 5-human AR transgenic mice exposed to high levels of 5alpha-dihydrotestosterone showed delayed hair regeneration, mimicking the AGA scalp. This effect is AR mediated, because treatment with the AR antagonist hydroxyflutamide inhibited the effect of dihydrotestosterone on hair growth. These results support the hypothesis that androgen-mediated hair loss is AR dependent and suggest that AR and beta-catenin mediate this effect. These mice can now be used to test new therapeutic agents for the treatment of AGA, accelerating the drug discovery process.

Study of gene expression alteration in male androgenetic alopecia: evidence of predominant molecular signalling pathways.

PubMed

Michel, L; Reygagne, P; Benech, P; Jean-Louis, F; Scalvino, S; Ly Ka So, S; Hamidou, Z; Bianovici, S; Pouch, J; Ducos, B; Bonnet, M; Bensussan, A; Patatian, A; Lati, E; Wdzieczak-Bakala, J; Choulot, J-C; Loing, E; Hocquaux, M

2017-11-01

Male androgenetic alopecia (AGA) is the most common form of hair loss in men. It is characterized by a distinct pattern of progressive hair loss starting from the frontal area and the vertex of the scalp. Although several genetic risk loci have been identified, relevant genes for AGA remain to be defined. To identify biomarkers associated with AGA. Molecular biomarkers associated with premature AGA were identified through gene expression analysis using cDNA generated from scalp vertex biopsies of hairless or bald men with premature AGA, and healthy volunteers. This monocentric study reveals that genes encoding mast cell granule enzymes, inflammatory mediators and immunoglobulin-associated immune mediators were significantly overexpressed in AGA. In contrast, underexpressed genes appear to be associated with the Wnt/β-catenin and bone morphogenic protein/transforming growth factor-β signalling pathways. Although involvement of these pathways in hair follicle regeneration is well described, functional interpretation of the transcriptomic data highlights different events that account for their inhibition. In particular, one of these events depends on the dysregulated expression of proopiomelanocortin, as confirmed by polymerase chain reaction and immunohistochemistry. In addition, lower expression of CYP27B1 in patients with AGA supports the notion that changes in vitamin D metabolism contributes to hair loss. This study provides compelling evidence for distinct molecular events contributing to alopecia that may pave the way for new therapeutic approaches. © 2017 British Association of Dermatologists.

Gene expression analysis of parthenogenetic embryonic development of the pea aphid, Acyrthosiphon pisum, suggests that aphid parthenogenesis evolved from meiotic oogenesis.

PubMed

Srinivasan, Dayalan G; Abdelhady, Ahmed; Stern, David L

2014-01-01

Aphids exhibit a form of phenotypic plasticity, called polyphenism, in which genetically identical females reproduce sexually during one part of the life cycle and asexually (via parthenogenesis) during the remainder of the life cycle. The molecular basis for aphid parthenogenesis is unknown. Cytological observations of aphid parthenogenesis suggest that asexual oogenesis evolved either through a modification of meiosis or from a mitotic process. As a test of these alternatives, we assessed the expression levels and expression patterns of canonical meiotic recombination and germline genes in the sexual and asexual ovaries of the pea aphid, Acyrthosiphon pisum. We observed expression of all meiosis genes in similar patterns in asexual and sexual ovaries, with the exception that some genes encoding Argonaute-family members were not expressed in sexual ovaries. In addition, we observed that asexual aphid tissues accumulated unspliced transcripts of Spo11, whereas sexual aphid tissues accumulated primarily spliced transcripts. In situ hybridization revealed Spo11 transcript in sexual germ cells and undetectable levels of Spo11 transcript in asexual germ cells. We also found that an obligately asexual strain of pea aphid produced little spliced Spo11 transcript. Together, these results suggest that parthenogenetic oogenesis evolved from a meiosis-like, and not a mitosis-like, process and that the aphid reproductive polyphenism may involve a modification of Spo11 gene activity.

Gene Expression Analysis of Parthenogenetic Embryonic Development of the Pea Aphid, Acyrthosiphon pisum, Suggests That Aphid Parthenogenesis Evolved from Meiotic Oogenesis

PubMed Central

Srinivasan, Dayalan G.; Abdelhady, Ahmed; Stern, David L.

2014-01-01

Aphids exhibit a form of phenotypic plasticity, called polyphenism, in which genetically identical females reproduce sexually during one part of the life cycle and asexually (via parthenogenesis) during the remainder of the life cycle. The molecular basis for aphid parthenogenesis is unknown. Cytological observations of aphid parthenogenesis suggest that asexual oogenesis evolved either through a modification of meiosis or from a mitotic process. As a test of these alternatives, we assessed the expression levels and expression patterns of canonical meiotic recombination and germline genes in the sexual and asexual ovaries of the pea aphid, Acyrthosiphon pisum. We observed expression of all meiosis genes in similar patterns in asexual and sexual ovaries, with the exception that some genes encoding Argonaute-family members were not expressed in sexual ovaries. In addition, we observed that asexual aphid tissues accumulated unspliced transcripts of Spo11, whereas sexual aphid tissues accumulated primarily spliced transcripts. In situ hybridization revealed Spo11 transcript in sexual germ cells and undetectable levels of Spo11 transcript in asexual germ cells. We also found that an obligately asexual strain of pea aphid produced little spliced Spo11 transcript. Together, these results suggest that parthenogenetic oogenesis evolved from a meiosis-like, and not a mitosis-like, process and that the aphid reproductive polyphenism may involve a modification of Spo11 gene activity. PMID:25501006

Effect of Intra- and Extrauterine Growth on Long-Term Neurologic Outcomes of Very Preterm Infants.

PubMed

Guellec, Isabelle; Lapillonne, Alexandre; Marret, Stephane; Picaud, Jean-Charles; Mitanchez, Delphine; Charkaluk, Marie-Laure; Fresson, Jeanne; Arnaud, Catherine; Flamand, Cyril; Cambonie, Gilles; Kaminski, Monique; Roze, Jean-Christophe; Ancel, Pierre-Yves

2016-08-01

To determine whether extrauterine growth is associated with neurologic outcomes and if this association varies by prenatal growth profile. For 1493 preterms from the EPIPAGE (Étude Épidémiologique sur les Petits Âges Gestationnels [Epidemiological Study on Small Gestational Ages]) cohort, appropriate for gestational-age (AGA) was defined by birth weight >-2 SD and small for gestational-age (SGA) by birth weight ≤-2 SD. Extra-uterine growth was defined by weight gain or loss between birth and 6 months by z-score change. Growth following-the-curve (FTC) was defined as weight change -1 to +1 SD, catch-down-growth (CD) as weight loss ≥1 SD, and catch-up-growth (CU) as weight gain ≥1 SD. At 5 years, a complete medical examination (n = 1305) and cognitive evaluation with the Kauffman Assessment Battery for Children (n = 1130) were performed. Behavioral difficulties at 5 years and school performance at 8 years were assessed (n = 1095). Overall, 42.5% of preterms were AGA-FTC, 20.2% AGA-CD, 17.1% AGA-CU, 5.6% SGA-FTC, and 14.5% SGA-CU. Outcomes did not differ between CU and FTC preterm AGA infants. Risk of cerebral palsy was greater for AGA-CD compared with AGA-FTC (aOR 2.26 [95% CI 1.37-3.72]). As compared with children with SGA-CU, SGA-FTC children showed no significant increased risk of cognitive deficiency (aOR 1.41[0.94-2.12]) or school difficulties (aOR 1.60 [0.84-3.03]). Compared with AGA-FTC, SGA showed increased risk of cognitive deficiency (SGA-FTC aOR 2.19 [1.25-3.84]) and inattention-hyperactivity (SGA-CU aOR 1.65 [1.05-2.60]). Deficient postnatal growth was associated with poor neurologic outcome for AGA and SGA preterm infants. CU growth does not add additional benefits. Regardless of type of postnatal growth, SGA infants showed behavioral problems and cognitive deficiency. Copyright © 2016 Elsevier Inc. All rights reserved.

Geometry correction Algorithm for UAV Remote Sensing Image Based on Improved Neural Network

NASA Astrophysics Data System (ADS)

Liu, Ruian; Liu, Nan; Zeng, Beibei; Chen, Tingting; Yin, Ninghao

2018-03-01

Aiming at the disadvantage of current geometry correction algorithm for UAV remote sensing image, a new algorithm is proposed. Adaptive genetic algorithm (AGA) and RBF neural network are introduced into this algorithm. And combined with the geometry correction principle for UAV remote sensing image, the algorithm and solving steps of AGA-RBF are presented in order to realize geometry correction for UAV remote sensing. The correction accuracy and operational efficiency is improved through optimizing the structure and connection weight of RBF neural network separately with AGA and LMS algorithm. Finally, experiments show that AGA-RBF algorithm has the advantages of high correction accuracy, high running rate and strong generalization ability.

Arginaseless Neurospora: Genetics, Physiology, and Polyamine Synthesis

PubMed Central

Davis, Rowland H.; Lawless, Mary B.; Port, Loretta A.

1970-01-01

Four arginaseless mutants of Neurospora crassa have been isolated. All carry mutations which lie at a single locus, aga, on linkage group VIIR. A study of aga strains shows the arginase reaction to be the major, perhaps the only, route of arginine consumption in Neurospora other than protein synthesis. Ornithine-δ-transaminase, the second enzyme of the arginine catabolic pathway, is present and normally inducible by arginine in aga strains, and ornithine transcarbamylase, an enzyme of arginine synthesis, also has normal activity. Arginine inhibits the growth of aga strains. The inhibition can be reversed by spermidine, putrescine (1,4-diaminobutane), or ornithine. The results suggest that ornithine is the major source of the putrescine moiety of polyamines in Neurospora, and that putrescine is an essential growth factor for this organism. The inhibition of aga strains by arginine can be attributed to feedback inhibition of ornithine synthesis by arginine, combined with the complete lack of ornithine normally provided by the arginase reaction. PMID:5419257

Adaptations to different habitats in sexual and asexual populations of parasitoid wasps: a meta-analysis.

PubMed

Amat, Isabelle; van Alphen, Jacques J M; Kacelnik, Alex; Desouhant, Emmanuel; Bernstein, Carlos

2017-01-01

Coexistence of sexual and asexual populations remains a key question in evolutionary ecology. We address the question how an asexual and a sexual form of the parasitoid Venturia canescens can coexist in southern Europe. We test the hypothesis that both forms are adapted to different habitats within their area of distribution. Sexuals inhabit natural environments that are highly unpredictable, and where density of wasps and their hosts is low and patchily distributed. Asexuals instead are common in anthropic environments (e.g., grain stores) where host outbreaks offer periods when egg-load is the main constraint on reproductive output. We present a meta-analysis of known adaptations to these habitats. Differences in behavior, physiology and life-history traits between sexual and asexual wasps were standardized in term of effect size (Cohen's d value; Cohen, 1988). Seeking consilience from the differences between multiple traits, we found that sexuals invest more in longevity at the expense of egg-load, are more mobile, and display higher plasticity in response to thermal variability than asexual counterparts. Thus, each form has consistent multiple adaptations to the ecological circumstances in the contrasting environments.

Neutral and selection-driven decay of sexual traits in asexual stick insects

PubMed Central

Schwander, Tanja; Crespi, Bernard J.; Gries, Regine; Gries, Gerhard

2013-01-01

Environmental shifts and lifestyle changes may result in formerly adaptive traits becoming non-functional or maladaptive. The subsequent decay of such traits highlights the importance of natural selection for adaptations, yet its causes have rarely been investigated. To study the fate of formerly adaptive traits after lifestyle changes, we evaluated sexual traits in five independently derived asexual lineages, including traits that are specific to males and therefore not exposed to selection. At least four of the asexual lineages retained the capacity to produce males that display normal courtship behaviours and are able to fertilize eggs of females from related sexual species. The maintenance of male traits may stem from pleiotropy, or from these traits only regressing via drift, which may require millions of years to generate phenotypic effects. By contrast, we found parallel decay of sexual traits in females. Asexual females produced altered airborne and contact signals, had modified sperm storage organs, and lost the ability to fertilize their eggs, impeding reversals to sexual reproduction. Female sexual traits were decayed even in recently derived asexuals, suggesting that trait changes following the evolution of asexuality, when they occur, proceed rapidly and are driven by selective processes rather than drift. PMID:23782880

Adaptations to different habitats in sexual and asexual populations of parasitoid wasps: a meta-analysis

PubMed Central

van Alphen, Jacques J.M.; Kacelnik, Alex; Desouhant, Emmanuel

2017-01-01

Background Coexistence of sexual and asexual populations remains a key question in evolutionary ecology. We address the question how an asexual and a sexual form of the parasitoid Venturia canescens can coexist in southern Europe. We test the hypothesis that both forms are adapted to different habitats within their area of distribution. Sexuals inhabit natural environments that are highly unpredictable, and where density of wasps and their hosts is low and patchily distributed. Asexuals instead are common in anthropic environments (e.g., grain stores) where host outbreaks offer periods when egg-load is the main constraint on reproductive output. Methods We present a meta-analysis of known adaptations to these habitats. Differences in behavior, physiology and life-history traits between sexual and asexual wasps were standardized in term of effect size (Cohen’s d value; Cohen, 1988). Results Seeking consilience from the differences between multiple traits, we found that sexuals invest more in longevity at the expense of egg-load, are more mobile, and display higher plasticity in response to thermal variability than asexual counterparts. Discussion Thus, each form has consistent multiple adaptations to the ecological circumstances in the contrasting environments. PMID:28924495

Asexual Reproduction in Holothurians

PubMed Central

Dolmatov, Igor Yu.

2014-01-01

Aspects of asexual reproduction in holothurians are discussed. Holothurians are significant as fishery and aquaculture items and have high commercial value. The last review on holothurian asexual reproduction was published 18 years ago and included only 8 species. An analysis of the available literature shows that asexual reproduction has now been confirmed in 16 holothurian species. Five additional species are also most likely capable of fission. The recent discovery of new fissiparous holothurian species indicates that this reproduction mode is more widespread in Holothuroidea than previously believed. New data about the history of the discovery of asexual reproduction in holothurians, features of fission, and regeneration of anterior and posterior fragments are described here. Asexual reproduction is obviously controlled by the integrated systems of the organism, primarily the nervous system. Special molecular mechanisms appear to determine the location where fission occurs along the anterior-posterior axis of the body. Alteration of the connective tissue strength of the body wall may play an important role during fission of holothurians. The basic mechanism of fission is the interaction of matrix metalloproteinases, their inhibitors, and enzymes forming cross-link complexes between fibrils of collagen. The population dynamics of fissiparous holothurians are discussed. PMID:25405228

Anti-ganglioside antibodies in patients with systemic lupus erythematosus and neurological manifestations.

PubMed

Labrador-Horrillo, M; Martinez-Valle, F; Gallardo, E; Rojas-Garcia, R; Ordi-Ros, J; Vilardell, M

2012-05-01

Anti-ganglioside antibodies (AGA) have been associated with several peripheral neuropathies, such as Miller-Fisher syndrome, Guillain-Barré syndrome and multifocal motor neuropathy. They have also been studied in patients with systemic lupus erythematosus (SLE), focusing on neuropsychiatric manifestations and peripheral neuropathy, but the results are contradictory. To study the presence of AGA in a large cohort of patients with SLE and neuropsychiatric manifestations. Serum from 65 consecutive patients with SLE and neuropsychiatric manifestations, collected from 1985 to 2009, was tested for the presence of AGA antibodies (GM1, GM2, GM3, asialo-GM1 GD1a, GD1b, GD3, GT1b, GQ1b) using a standard enzyme-linked immunosorbent assay ELISA test (INCAT 1999) and thin layer chromatography (TLC). Positive results for asialo-GM1 (IgM) were found in 10 patients, 6 were positive for asialo-GM1 (IgM and IgG), and 4 were positive for other AGA such as GM1, GM2, GM3, GD1b, GT1b, GD3, (mainly IgM). Clinical and statistical studies showed no correlation between AGA and neuropsychiatric manifestations of SLE. Although some patients showed reactivity to AGA, these antibodies are not a useful marker of neuropsychiatric manifestations in SLE patients.

Comparison of serum 25-hydroxy vitamin D levels between mothers with small for gestational age and appropriate for gestational age newborns in Kerman.

PubMed

Mirzaei, Fatemeh; Amiri Moghadam, Tayebeh; Arasteh, Peyman

2015-04-01

Vitamin D deficiency during pregnancy is associated with some adverse pregnancy outcomes but its relationship with fetal growth is unknown. We compared the 25-hydroxy vitamin D levels between mothers and their small for gestational age (SGA) newborns with mothers and their appropriate for gestational age (AGA) newborns. The study population included pregnant women that referred to Afzalipour Hospital in Kerman from 2012 to 2013. The case and control group consisted of 40 pregnant mothers with SGA and AGA newborns, respectively. The maternal and infants 25-hydroxy vitamin D levels were measured in the two groups. 25-hydroxy vitamin D deficiency (<20 ng/ml) was statistically higher in women with SGA newborns in comparison to women with AGA newborns (p=0.003).Vitamin D deficiency was higher among the SGA newborns in comparison to AGA newborns (25% vs. 17.5%), although this finding was not statistically meaningful (p=0.379). The relationship of vitamin D deficiency levels between mothers and infants in both the SGA group and the AGA group was significant. Our study reveals a high prevalence of vitamin D deficiency in women with SGA infants in comparison to women with AGA children. In addition, maternal vitamin D deficiency is associated with its deficiency in newborns.

P-type calcium channels in rat neocortical neurones.

PubMed Central

Brown, A M; Sayer, R J; Schwindt, P C; Crill, W E

1994-01-01

1. The high threshold, voltage-activated (HVA) calcium current was recorded from acutely isolated rat neocortical pyramidal neurones using the whole-cell patch technique to examine the effect of agents that block P-type calcium channels and to compare their effects to those of omega-conotoxin GVIA (omega-CgTX) and nifedipine. 2. When applied at a saturating concentration (100 nM) the peptide toxins omega-Aga-IVA and synthetic omega-Aga-IVA blocked 31.5 and 33.0% of the HVA current respectively. 3. A saturating concentration of nifedipine (10 microM) inhibited 48.2% of the omega-Aga-IVA-sensitive current, whereas saturating concentrations of both omega-Aga-IVA (100 nM) and omega-CgTX (10 microM) blocked separate specific components of the HVA current. 4. Partially purified funnel web spider toxin (FTX) at a dilution of 1:1000 blocked 81.4% of the HVA current and occluded the inhibitory effect of omega-Aga-IVA. Synthetic FTX 3.3 arginine polyamine (sFTX) at a concentration of 1 mM blocked 61.2% of the HVA current rapidly and reversibly. The effects of sFTX were partially occluded by pre-application of omega-Aga-IVA. We conclude that neither FTX nor sFTX blocked a specific component of the HVA current in these cells. 5. In view of the specificity of omega-Aga-IVA for P-type calcium channels in other preparations and for a specific component of the HVA current in dissociated neocortical neurones we conclude that about 30% of the HVA current in these neurones flow through P-channels. PMID:7517449

P-type calcium channels in rat neocortical neurones.

PubMed

Brown, A M; Sayer, R J; Schwindt, P C; Crill, W E

1994-03-01

1. The high threshold, voltage-activated (HVA) calcium current was recorded from acutely isolated rat neocortical pyramidal neurones using the whole-cell patch technique to examine the effect of agents that block P-type calcium channels and to compare their effects to those of omega-conotoxin GVIA (omega-CgTX) and nifedipine. 2. When applied at a saturating concentration (100 nM) the peptide toxins omega-Aga-IVA and synthetic omega-Aga-IVA blocked 31.5 and 33.0% of the HVA current respectively. 3. A saturating concentration of nifedipine (10 microM) inhibited 48.2% of the omega-Aga-IVA-sensitive current, whereas saturating concentrations of both omega-Aga-IVA (100 nM) and omega-CgTX (10 microM) blocked separate specific components of the HVA current. 4. Partially purified funnel web spider toxin (FTX) at a dilution of 1:1000 blocked 81.4% of the HVA current and occluded the inhibitory effect of omega-Aga-IVA. Synthetic FTX 3.3 arginine polyamine (sFTX) at a concentration of 1 mM blocked 61.2% of the HVA current rapidly and reversibly. The effects of sFTX were partially occluded by pre-application of omega-Aga-IVA. We conclude that neither FTX nor sFTX blocked a specific component of the HVA current in these cells. 5. In view of the specificity of omega-Aga-IVA for P-type calcium channels in other preparations and for a specific component of the HVA current in dissociated neocortical neurones we conclude that about 30% of the HVA current in these neurones flow through P-channels.

Association between androgenetic alopecia and coronary artery disease in young male patients.

PubMed

Sharma, Kamal H; Jindal, Anchal

2014-01-01

Several studies have demonstrated an association between androgenetic alopecia (AGA) and cardiovascular disease. Still controversies exist regarding the association. Are they truly associated? The purpose of the present study was to assess the prevalence of AGA and establish its association in young (<45 years) Asian Indian Gujarati male patients having coronary artery disease (CAD). Case-control prospective multicentric study was carried out on 424 men. Case group consisted of 212 male subjects having CAD (Group 1) and another 212, either sibling or first degree male relative of the case subjects (having no evidence of CAD) were considered as the control group (Group 2). Age, total cholesterol, incidence of diabetes mellitus, and hypertension were similar in both groups. The degree of alopecia was assessed using the Norwood-Hamilton scale for men. Statistical analysis was performed using Chi-square test. AGA was found in 80 (37.73%) young CAD patients (Group 1), whereas 44 (20.7%) of patients had alopecia in the control group (Group 2). There was statistically significant association between male AGA and CAD (P = 0.001). Odds ratio was 2.70 (95% confidence interval [CI], 1.72 ± 4.26). Statistically significant association was found between high grade baldness (Grades IV-VII) and CAD in young men (P < 0.05). Odds ratio = 2.36 (95% CI, 1.108 ± 5.033). There is statistically significant association of AGA in young Asian Gujarati male with CAD and the prevalence of AGA in young CAD patient is 37.73%. This study implies early onset AGA in male is independently associated with CAD, though mechanisms need to be investigated.

Association of anti-gangliosides antibodies and anti-CMV antibodies in Guillain-Barré syndrome.

PubMed

Wang, Lijuan; Shao, Chunqing; Yang, Chunjiao; Kang, Xixiong; Zhang, Guojun

2017-05-01

Numerous types of infection were closely related to GBS, mainly including Campylobacter jejuni , Cytomegalovirus, which may lead to the production of anti-gangliosides antibodies (AGA) . Currently, although there are increased studies on the AGA and a few studies of anti-CMV antibodies in GBS, the association between them remains poorly documented. Therefore, our research aims to analyze the correlation of anti-CMV antibodies and AGA in GBS. A total of 29 patients with GBS were enrolled in this study. The CMV antibodies were tested by the electrochemiluminescence immunoassay "ECLIA" (Roche Diagnostics GmbH). The serum gangliosides were determined by The EUROLINE test kit. Of the 29 patients with GBS, 9 (31%) were AGA-seropositive, in which 22 were CMV-IgG positive in CSF at the same time, but all 29 samples were CMV-IgM negative in both serum and CSF. In the AGA-positive group, the rate of both serum and CSF positive was 87.5% (7/8), higher than 50% (7/14) of the negative group, although no statistical significance was found. In addition, we found that there was a trend of higher ratio of men, a younger age onset, less frequent preceding infection, a higher level of CSF proteins, and less frequent cranial nerve deficits, although the data did not reach a statistical significance. In spite of no statistical significance association was found between serum AGA and CMV-IgG in serum and CSF. However, we found that there was a trend of high positive rate of both serum and CSF-CMV-IgG in AGA-positive than the negative group. So we should further expand the sample size to analyze the association between AGA and CMV or other neurotropic virus antibodies in various diseases, to observe whether they could be serological marker of these diseases (especially GBS) or the underlying pathogenesis.

Routine delivery of artemisinin-based combination treatment at fixed health facilities reduces malaria prevalence in Tanzania: an observational study

PubMed Central

2012-01-01

Background Artemisinin-based combination therapy (ACT) has been promoted as a means to reduce malaria transmission due to their ability to kill both asexual blood stages of malaria parasites, which sustain infections over long periods and the immature derived sexual stages responsible for infecting mosquitoes and onward transmission. Early studies reported a temporal association between ACT introduction and reduced malaria transmission in a number of ecological settings. However, these reports have come from areas with low to moderate malaria transmission, been confounded by the presence of other interventions or environmental changes that may have reduced malaria transmission, and have not included a comparison group without ACT. This report presents results from the first large-scale observational study to assess the impact of case management with ACT on population-level measures of malaria endemicity in an area with intense transmission where the benefits of effective infection clearance might be compromised by frequent and repeated re-infection. Methods A pre-post observational study with a non-randomized comparison group was conducted at two sites in Tanzania. Both sites used sulphadoxine-pyrimethamine (SP) monotherapy as a first-line anti-malarial from mid-2001 through 2002. In 2003, the ACT, artesunate (AS) co-administered with SP (AS + SP), was introduced in all fixed health facilities in the intervention site, including both public and registered non-governmental facilities. Population-level prevalence of Plasmodium falciparum asexual parasitaemia and gametocytaemia were assessed using light microscopy from samples collected during representative household surveys in 2001, 2002, 2004, 2005 and 2006. Findings Among 37,309 observations included in the analysis, annual asexual parasitaemia prevalence in persons of all ages ranged from 11% to 28% and gametocytaemia prevalence ranged from <1% to 2% between the two sites and across the five survey years. A multivariable logistic regression model was fitted to adjust for age, socioeconomic status, bed net use and rainfall. In the presence of consistently high coverage and efficacy of SP monotherapy and AS + SP in the comparison and intervention areas, the introduction of ACT in the intervention site was associated with a modest reduction in the adjusted asexual parasitaemia prevalence of 5 percentage-points or 23% (p < 0.0001) relative to the comparison site. Gametocytaemia prevalence did not differ significantly (p = 0.30). Interpretation The introduction of ACT at fixed health facilities only modestly reduced asexual parasitaemia prevalence. ACT is effective for treatment of uncomplicated malaria and should have substantial public health impact on morbidity and mortality, but is unlikely to reduce malaria transmission substantially in much of sub-Saharan Africa where individuals are rapidly re-infected. PMID:22545573

Evolutionary branching under multi-dimensional evolutionary constraints.

PubMed

Ito, Hiroshi; Sasaki, Akira

2016-10-21

The fitness of an existing phenotype and of a potential mutant should generally depend on the frequencies of other existing phenotypes. Adaptive evolution driven by such frequency-dependent fitness functions can be analyzed effectively using adaptive dynamics theory, assuming rare mutation and asexual reproduction. When possible mutations are restricted to certain directions due to developmental, physiological, or physical constraints, the resulting adaptive evolution may be restricted to subspaces (constraint surfaces) with fewer dimensionalities than the original trait spaces. To analyze such dynamics along constraint surfaces efficiently, we develop a Lagrange multiplier method in the framework of adaptive dynamics theory. On constraint surfaces of arbitrary dimensionalities described with equality constraints, our method efficiently finds local evolutionarily stable strategies, convergence stable points, and evolutionary branching points. We also derive the conditions for the existence of evolutionary branching points on constraint surfaces when the shapes of the surfaces can be chosen freely. Copyright © 2016 Elsevier Ltd. All rights reserved.

Accelerated crossing of fitness valleys through division of labor and cheating in asexual populations

NASA Astrophysics Data System (ADS)

Komarova, Natalia L.; Urwin, Erin; Wodarz, Dominik

2012-12-01

Complex traits can require the accumulation of multiple mutations that are individually deleterious. Their evolution requires a fitness valley to be crossed, which can take relatively long time spans. A new evolutionary mechanism is described that accelerates the emergence of complex phenotypes, based on a ``division of labor'' game and the occurrence of cheaters. If each intermediate mutation leads to a product that can be shared with others, the complex type can arise relatively quickly as an emergent property among cooperating individuals, without any given individual having to accumulate all mutations. Moreover, the emergence of cheaters that destroy cooperative interactions can lead to the emergence of individuals that have accumulated all necessary mutations on a time scale that is significantly faster than observed in the absence of cooperation and cheating. Application of this mechanism to somatic and microbial evolution is discussed, including evolutionary processes in tumors, biofilms, and viral infections.

Accelerated crossing of fitness valleys through division of labor and cheating in asexual populations

PubMed Central

Komarova, Natalia L.; Urwin, Erin; Wodarz, Dominik

2012-01-01

Complex traits can require the accumulation of multiple mutations that are individually deleterious. Their evolution requires a fitness valley to be crossed, which can take relatively long time spans. A new evolutionary mechanism is described that accelerates the emergence of complex phenotypes, based on a “division of labor” game and the occurrence of cheaters. If each intermediate mutation leads to a product that can be shared with others, the complex type can arise relatively quickly as an emergent property among cooperating individuals, without any given individual having to accumulate all mutations. Moreover, the emergence of cheaters that destroy cooperative interactions can lead to the emergence of individuals that have accumulated all necessary mutations on a time scale that is significantly faster than observed in the absence of cooperation and cheating. Application of this mechanism to somatic and microbial evolution is discussed, including evolutionary processes in tumors, biofilms, and viral infections. PMID:23209877

Association Between Androgenetic Alopecia and Coronary Artery Disease in Young Male Patients

PubMed Central

Sharma, Kamal H; Jindal, Anchal

2014-01-01

Background: Several studies have demonstrated an association between androgenetic alopecia (AGA) and cardiovascular disease. Still controversies exist regarding the association. Are they truly associated? Objective: The purpose of the present study was to assess the prevalence of AGA and establish its association in young (<45 years) Asian Indian Gujarati male patients having coronary artery disease (CAD). Materials and Methods: Case-control prospective multicentric study was carried out on 424 men. Case group consisted of 212 male subjects having CAD (Group 1) and another 212, either sibling or first degree male relative of the case subjects (having no evidence of CAD) were considered as the control group (Group 2). Age, total cholesterol, incidence of diabetes mellitus, and hypertension were similar in both groups. The degree of alopecia was assessed using the Norwood-Hamilton scale for men. Statistical analysis was performed using Chi-square test. Results: AGA was found in 80 (37.73%) young CAD patients (Group 1), whereas 44 (20.7%) of patients had alopecia in the control group (Group 2). There was statistically significant association between male AGA and CAD (P = 0.001). Odds ratio was 2.70 (95% confidence interval [CI], 1.72 ± 4.26). Statistically significant association was found between high grade baldness (Grades IV-VII) and CAD in young men (P < 0.05). Odds ratio = 2.36 (95% CI, 1.108 ± 5.033). There is statistically significant association of AGA in young Asian Gujarati male with CAD and the prevalence of AGA in young CAD patient is 37.73%. Conclusion: This study implies early onset AGA in male is independently associated with CAD, though mechanisms need to be investigated. PMID:25114445

Birth weight and long-term metabolic outcomes: does the definition of smallness matter?

PubMed

Verkauskiene, R; Figueras, F; Deghmoun, S; Chevenne, D; Gardosi, J; Levy-Marchal, M

2008-01-01

To establish the role of individual definition of smallness at birth in the association between birth weight and long-term metabolic outcomes. Lipid profile and oral glucose tolerance test were performed in young adults (22 years) born either small (SGA) or appropriate for gestational age (AGA). AGA/SGA were defined by both population-based and customized methods adjusting for individual maternal/pregnancy characteristics. 825 individuals were classified as AGA and 575 as SGA by both methods, 131 were SGA by the population-based method only (SGA(pop)) and 22 were SGA by the customized method only (SGA(cust)). SGA(cust) subjects had higher total cholesterol and triglyceride levels and lower high-density lipoprotein cholesterol concentrations than SGA(pop) and AGA subjects, however, insignificantly when adjusted for age, gender and body mass index. The homeostasis model assessment for insulin resistance (HOMA-IR) index was higher in the SGA(cust) (p = 0.05) and SGA(pop) (p = 0.02) versus the AGA group. Controlling for the HOMA-IR index, the insulinogenic index was significantly lower in the SGA(cust) versus SGA(pop) (p = 0.001) and AGA (p = 0.003) groups. In SGA(cust) individuals, the HOMA-IR index was clearly shifted to higher, while the insulinogenic index to lower tertiles of AGA distribution; SGA(pop) subjects had the HOMA-IR and insulinogenic index predominantly in the highest tertiles. Individualized birth weight standards allow to better identify subjects who failed to reach their genetic potential of intrauterine growth and are at higher risk of metabolic disturbances and impaired insulin secretion later in life. Copyright 2008 S. Karger AG, Basel.

Sex-specific gene expression during asexual development of Neurospora crassa.

PubMed

Wang, Zheng; Kin, Koryu; López-Giráldez, Francesc; Johannesson, Hanna; Townsend, Jeffrey P

2012-07-01

The impact of loci that determine sexual identity upon the asexual, dominant stage of fungal life history has been well studied. To investigate their impact, expression differences between strains of different mating type during asexual development were assayed, with RNA sampled from otherwise largely isogenic mat A and mat a strains of Neurospora crassa at early, middle, and late clonal stages of development. We observed significant differences in overall gene expression between mating types across clonal development, especially at late development stages. The expression levels of mating-type genes and pheromone genes were assayed by reverse transcription and quantitative PCR, revealing expression of pheromone and receptor genes in strains of both mating types in all development stages, and revealing that mating type (mat) genes were increasingly expressed over the course of asexual development. Interestingly, among differentially expressed genes, the mat A genotype more frequently exhibited a higher expression level than mat a, and demonstrated greater transcriptional regulatory dynamism. Significant up-regulation of expression was observed for many late light-responsive genes at late asexual development stages. Further investigation of the impact of light and the roles of light response genes in asexual development of both mating types are warranted. Copyright © 2012 Elsevier Inc. All rights reserved.

Asexual sporulation facilitates adaptation: The emergence of azole resistance in Aspergillus fumigatus.

PubMed

Zhang, Jianhua; Debets, Alfons J M; Verweij, Paul E; Melchers, Willem J G; Zwaan, Bas J; Schoustra, Sijmen E

2015-10-01

Understanding the occurrence and spread of azole resistance in Aspergillus fumigatus is crucial for public health. It has been hypothesized that asexual sporulation, which is abundant in nature, is essential for phenotypic expression of azole resistance mutations in A. fumigatus facilitating subsequent spread through natural selection. Furthermore, the disease aspergilloma is associated with asexual sporulation within the lungs of patients and the emergence of azole resistance. This study assessed the evolutionary advantage of asexual sporulation by growing the fungus under pressure of one of five different azole fungicides over seven weeks and by comparing the rate of adaptation between scenarios of culturing with and without asexual sporulation. Results unequivocally show that asexual sporulation facilitates adaptation. This can be explained by the combination of more effective selection because of the transition from a multicellular to a unicellular stage, and by increased mutation supply due to the production of spores, which involves numerous mitotic divisions. Insights from this study are essential to unravel the resistance mechanisms of sporulating pathogens to chemical compounds and disease agents in general, and for designing strategies that prevent or overcome the emerging threat of azole resistance in particular. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

The roles of sexual and asexual reproduction in the origin and dissemination of strains causing fungal infectious disease outbreaks.

PubMed

Ashu, Eta Ebasi; Xu, Jianping

2015-12-01

Sexual reproduction commonly refers to the reproductive process in which genomes from two sources are combined into a single cell through mating and then the zygote genomes are partitioned to progeny cells through meiosis. Reproduction in the absence of mating and meiosis is referred to as asexual or clonal reproduction. One major advantage of sexual reproduction is that it generates genetic variation among progeny which may allow for faster adaptation of the population to novel and/or stressful environments. However, adaptation to stressful or new environments can still occur through mutation, in the absence of sex. In this review, we analyzed the relative contributions of sexual and asexual reproduction in the origin and spread of strains causing fungal infectious diseases outbreaks. The necessity of sex and the ability of asexual fungi to initiate outbreaks are discussed. We propose a framework that relates the modes of reproduction to the origin and propagation of fungal disease outbreaks. Our analyses suggest that both sexual and asexual reproduction can play critical roles in the origin of outbreak strains and that the rapid spread of outbreak strains is often accomplished through asexual expansion. Copyright © 2015 Elsevier B.V. All rights reserved.

Heritable gene expression differences between apomictic clone members in Taraxacum officinale: Insights into early stages of evolutionary divergence in asexual plants.

PubMed

Ferreira de Carvalho, Julie; Oplaat, Carla; Pappas, Nikolaos; Derks, Martijn; de Ridder, Dick; Verhoeven, Koen J F

2016-03-08

Asexual reproduction has the potential to enhance deleterious mutation accumulation and to constrain adaptive evolution. One source of mutations that can be especially relevant in recent asexuals is activity of transposable elements (TEs), which may have experienced selection for high transposition rates in sexual ancestor populations. Predictions of genomic divergence under asexual reproduction therefore likely include a large contribution of transposable elements but limited adaptive divergence. For plants empirical insight into genome divergence under asexual reproduction remains limited. Here, we characterize expression divergence between clone members of a single apomictic lineage of the common dandelion (Taraxacum officinale) to contribute to our knowledge of genome evolution under asexuality. Using RNA-Seq, we show that about one third of heritable divergence within the apomictic lineage is driven by TEs and TE-related gene activity. In addition, we identify non-random transcriptional differences in pathways related to acyl-lipid and abscisic acid metabolisms which might reflect functional divergence within the apomictic lineage. We analyze SNPs in the transcriptome to assess genetic divergence between the apomictic clone members and reveal that heritable expression differences between the accessions are not explained simply by genome-wide genetic divergence. The present study depicts a first effort towards a more complete understanding of apomictic plant genome evolution. We identify abundant TE activity and ecologically relevant functional genes and pathways affecting heritable within-lineage expression divergence. These findings offer valuable resources for future work looking at epigenetic silencing and Cis-regulation of gene expression with particular emphasis on the effects of TE activity on asexual species' genome.

Hybridization and polyploidy enable genomic plasticity without sex in the most devastating plant-parasitic nematodes

PubMed Central

Perfus-Barbeoch, Laetitia; Da Rocha, Martine; Sallet, Erika; Bailly-Bechet, Marc; Castagnone-Sereno, Philippe; Flot, Jean-François; Kozlowski, Djampa K.; Cazareth, Julie; Couloux, Arnaud; Da Silva, Corinne; Guy, Julie; Kim-Jo, Yu-Jin; Rancurel, Corinne; Abad, Pierre; Wincker, Patrick

2017-01-01

Root-knot nematodes (genus Meloidogyne) exhibit a diversity of reproductive modes ranging from obligatory sexual to fully asexual reproduction. Intriguingly, the most widespread and devastating species to global agriculture are those that reproduce asexually, without meiosis. To disentangle this surprising parasitic success despite the absence of sex and genetic exchanges, we have sequenced and assembled the genomes of three obligatory ameiotic and asexual Meloidogyne. We have compared them to those of relatives able to perform meiosis and sexual reproduction. We show that the genomes of ameiotic asexual Meloidogyne are large, polyploid and made of duplicated regions with a high within-species average nucleotide divergence of ~8%. Phylogenomic analysis of the genes present in these duplicated regions suggests that they originated from multiple hybridization events and are thus homoeologs. We found that up to 22% of homoeologous gene pairs were under positive selection and these genes covered a wide spectrum of predicted functional categories. To biologically assess functional divergence, we compared expression patterns of homoeologous gene pairs across developmental life stages using an RNAseq approach in the most economically important asexually-reproducing nematode. We showed that >60% of homoeologous gene pairs display diverged expression patterns. These results suggest a substantial functional impact of the genome structure. Contrasting with high within-species nuclear genome divergence, mitochondrial genome divergence between the three ameiotic asexuals was very low, signifying that these putative hybrids share a recent common maternal ancestor. Transposable elements (TE) cover a ~1.7 times higher proportion of the genomes of the ameiotic asexual Meloidogyne compared to the sexual relative and might also participate in their plasticity. The intriguing parasitic success of asexually-reproducing Meloidogyne species could be partly explained by their TE-rich composite genomes, resulting from allopolyploidization events, and promoting plasticity and functional divergence between gene copies in the absence of sex and meiosis. PMID:28594822

Conventional and novel stem cell based therapies for androgenic alopecia

PubMed Central

Talavera-Adame, Dodanim; Newman, Daniella; Newman, Nathan

2017-01-01

The prevalence of androgenic alopecia (AGA) increases with age and it affects both men and women. Patients diagnosed with AGA may experience decreased quality of life, depression, and feel self-conscious. There are a variety of therapeutic options ranging from prescription drugs to non-prescription medications. Currently, AGA involves an annual global market revenue of US$4 billion and a growth rate of 1.8%, indicating a growing consumer market. Although natural and synthetic ingredients can promote hair growth and, therefore, be useful to treat AGA, some of them have important adverse effects and unknown mechanisms of action that limit their use and benefits. Biologic factors that include signaling from stem cells, dermal papilla cells, and platelet-rich plasma are some of the current therapeutic agents being studied for hair restoration with milder side effects. However, most of the mechanisms exerted by these factors in hair restoration are still being researched. In this review, we analyze the therapeutic agents that have been used for AGA and emphasize the potential of new therapies based on advances in stem cell technologies and regenerative medicine. PMID:28979149

Conventional and novel stem cell based therapies for androgenic alopecia.

PubMed

Talavera-Adame, Dodanim; Newman, Daniella; Newman, Nathan

2017-01-01

The prevalence of androgenic alopecia (AGA) increases with age and it affects both men and women. Patients diagnosed with AGA may experience decreased quality of life, depression, and feel self-conscious. There are a variety of therapeutic options ranging from prescription drugs to non-prescription medications. Currently, AGA involves an annual global market revenue of US$4 billion and a growth rate of 1.8%, indicating a growing consumer market. Although natural and synthetic ingredients can promote hair growth and, therefore, be useful to treat AGA, some of them have important adverse effects and unknown mechanisms of action that limit their use and benefits. Biologic factors that include signaling from stem cells, dermal papilla cells, and platelet-rich plasma are some of the current therapeutic agents being studied for hair restoration with milder side effects. However, most of the mechanisms exerted by these factors in hair restoration are still being researched. In this review, we analyze the therapeutic agents that have been used for AGA and emphasize the potential of new therapies based on advances in stem cell technologies and regenerative medicine.

Automated assembly of oligosaccharides containing multiple cis-glycosidic linkages

NASA Astrophysics Data System (ADS)

Hahm, Heung Sik; Hurevich, Mattan; Seeberger, Peter H.

2016-09-01

Automated glycan assembly (AGA) has advanced from a concept to a commercial technology that rapidly provides access to diverse oligosaccharide chains as long as 30-mers. To date, AGA was mainly employed to incorporate trans-glycosidic linkages, where C2 participating protecting groups ensure stereoselective couplings. Stereocontrol during the installation of cis-glycosidic linkages cannot rely on C2-participation and anomeric mixtures are typically formed. Here, we demonstrate that oligosaccharides containing multiple cis-glycosidic linkages can be prepared efficiently by AGA using monosaccharide building blocks equipped with remote participating protecting groups. The concept is illustrated by the automated syntheses of biologically relevant oligosaccharides bearing various cis-galactosidic and cis-glucosidic linkages. This work provides further proof that AGA facilitates the synthesis of complex oligosaccharides with multiple cis-linkages and other biologically important oligosaccharides.

Evolution of eukaryotic microbial pathogens via covert sexual reproduction

PubMed Central

Heitman, Joseph

2010-01-01

Sexual reproduction enables eukaryotic organisms to re-assort genetic diversity and purge deleterious mutations, producing better-fit progeny. Sex arose early and pervades eukaryotes. Fungal and parasite pathogens once thought asexual have maintained cryptic sexual cycles, including unisexual or parasexual reproduction. As pathogens become niche and host-adapted, sex appears to specialize to promote inbreeding and clonality yet maintain out-crossing potential. During self-fertile sexual modes, sex itself may generate genetic diversity de novo. Mating-type loci govern fungal sexual identity; how parasites establish sexual identity is unknown. Comparing and contrasting fungal and parasite sex promises to reveal how microbial pathogens evolved and are evolving. PMID:20638645

Experiments with digital organisms on the origin and maintenance of sex in changing environments.

PubMed

Misevic, Dusan; Ofria, Charles; Lenski, Richard E

2010-01-01

Many theories have been proposed to explain the evolution of sex, but the question remains unsettled owing to a paucity of compelling empirical tests. The crux of the problem is to understand the prevalence of sexual reproduction in the natural world, despite obvious costs relative to asexual reproduction. Here we perform experiments with digital organisms (evolving computer programs) to test the hypothesis that sexual reproduction is advantageous in changing environments. We varied the frequency and magnitude of environmental change, while the digital organisms could evolve their mode of reproduction as well as the traits affecting their fitness (reproductive rate) under the various conditions. Sex became the dominant mode of reproduction only when the environment changed rapidly and substantially (with particular functions changing from maladaptive to adaptive and vice versa). Even under these conditions, it was easier to maintain sexual reproduction than for sex to invade a formerly asexual population, although sometimes sex did invade and spread despite the obstacles to becoming established. Several diverse properties of the ancestral genomes, including epistasis and modularity, had no effect on the subsequent evolution of reproductive mode. Our study provides some limited support for the importance of changing environments to the evolution of sex, while also reinforcing the difficulty of evolving and maintaining sexual reproduction.

Genetic diversity in the interference selection limit.

PubMed

Good, Benjamin H; Walczak, Aleksandra M; Neher, Richard A; Desai, Michael M

2014-03-01

Pervasive natural selection can strongly influence observed patterns of genetic variation, but these effects remain poorly understood when multiple selected variants segregate in nearby regions of the genome. Classical population genetics fails to account for interference between linked mutations, which grows increasingly severe as the density of selected polymorphisms increases. Here, we describe a simple limit that emerges when interference is common, in which the fitness effects of individual mutations play a relatively minor role. Instead, similar to models of quantitative genetics, molecular evolution is determined by the variance in fitness within the population, defined over an effectively asexual segment of the genome (a "linkage block"). We exploit this insensitivity in a new "coarse-grained" coalescent framework, which approximates the effects of many weakly selected mutations with a smaller number of strongly selected mutations that create the same variance in fitness. This approximation generates accurate and efficient predictions for silent site variability when interference is common. However, these results suggest that there is reduced power to resolve individual selection pressures when interference is sufficiently widespread, since a broad range of parameters possess nearly identical patterns of silent site variability.

Genes necessary for expression of a virulence determinant and for transmission of Plasmodium falciparum are located on a 0.3-megabase region of chromosome 9.

PubMed Central

Day, K P; Karamalis, F; Thompson, J; Barnes, D A; Peterson, C; Brown, H; Brown, G V; Kemp, D J

1993-01-01

Virulence of the human malaria parasite Plasmodium falciparum is believed to relate to adhesion of parasitized erythrocytes to postcapillary venular endothelium (asexual cytoadherence). Transmission of malaria to the mosquito vector involves a switch from asexual to sexual development (gametocytogenesis). Continuous in vitro culture of P. falciparum frequently results in irreversible loss of asexual cytoadherence and gametocytogenesis. Field isolates and cloned lines differing in expression of these phenotypes were karyotyped by pulse-field gel electrophoresis. This analysis showed that expression of both phenotypes mapped to a 0.3-Mb subtelomeric deletion of chromosome 9. This deletion frequently occurs during adaptation of parasite isolates to in vitro culture. Parasites with this deletion did not express the variant surface agglutination phenotype and the putative asexual cytoadherence ligand designated P. falciparum erythrocyte membrane protein 1, which has recently been shown to undergo antigenic variation. The syntenic relationship between asexual cytoadherence and gametocytogenesis suggests that expression of these phenotypes is genetically linked. One explanation for this linkage is that both developmental pathways share a common cytoadherence mechanism. This proposed biological and genetic linkage between a virulence factor (asexual cytoadherence) and transmissibility (gametocytogenesis) would help explain why a high degree of virulence has evolved and been maintained in falciparum malaria. Images Fig. 1 Fig. 2 Fig. 3 PMID:8367496

Shifting from clonal to sexual reproduction in aphids: physiological and developmental aspects.

PubMed

Le Trionnaire, Gaël; Hardie, Jim; Jaubert-Possamai, Stéphanie; Simon, Jean-Christophe; Tagu, Denis

2008-08-01

Developmental biology is one of the fastest growing and fascinating research fields in life sciences. Among the wide range of embryonic development, a fundamental difference exists between organisms with sexual or asexual development. Aphids are unusual organisms which display alternative pathways of sexual and asexual development, the orientation of the pathway being determined by environmental conditions. These insects offer an adapted system in which to study developmental plasticity, because a side-by-side comparison of sexual and asexual development can be made in individuals with the same genotype. In this review, we describe the developmental mechanisms that have evolved in aphids for alternative sexual and asexual reproduction. In particular, we discuss how environmental cues orientate the reproductive mode of aphids from signal perception to endocrine regulation, and propose a comparative analysis of sexual and asexual gametogenesis and embryogenesis, which has been possible due to the development of molecular methods. As a result of the recent development of genomic resources in aphids, we expect these species will permit major advances in the study of the genomic basis underlying the choice of developmental fate and multiple reproduction strategies.

Evolution of the asexual queen succession system and its underlying mechanisms in termites.

PubMed

Matsuura, Kenji

2017-01-01

One major advantage of sexual reproduction over asexual reproduction is its promotion of genetic variation, although it reduces the genetic contribution to offspring. Queens of social insects double their contribution to the gene pool, while overuse of asexual reproduction may reduce the ability of the colony to adapt to environmental stress because of the loss of genetic diversity. Recent studies have revealed that queens of some termite species can solve this tradeoff by using parthenogenesis to produce the next generation of queens and sexual reproduction to produce other colony members. This reproductive system, known as asexual queen succession (AQS), has been identified in the subterranean termites Reticulitermes speratus, Reticulitermes virginicus and Reticulitermes lucifugus and in the Neotropical higher termites Embiratermes neotenicus and Cavitermes tuberosus The studies presented here have uncovered the unusual modes of reproduction in termites and have aimed to identify their underlying mechanisms. The study of AQS, the mixed use of sexual and asexual reproduction, is of fundamental importance as it may provide a key to solve the evolutionary paradox of sex. © 2017. Published by The Company of Biologists Ltd.

Differential effect of assisted reproductive technology and small-for-gestational age on fetal cardiac remodeling.

PubMed

Valenzuela-Alcaraz, B; Crispi, F; Cruz-Lemini, M; Bijnens, B; García-Otero, L; Sitges, M; Balasch, J; Gratacós, E

2017-07-01

Fetuses conceived by assisted reproductive technology (ART) and those that are small-for-gestational age (SGA) show cardiovascular remodeling in utero; however, these two conditions are often associated. We aimed to evaluate the differential effect of ART and SGA on fetal cardiac remodeling. This was a prospective cohort study of term singleton pregnancies seen at our department between April 2011 and September 2013. The cohort was divided according to fetal growth and mode of conception into the following four groups: 102 appropriate-for-gestational-age (AGA) fetuses conceived spontaneously (controls), 72 AGA fetuses conceived by ART (ART-AGA), 31 SGA fetuses conceived by ART (ART-SGA) and 28 SGA fetuses conceived naturally (Spont-SGA). SGA was defined as birth weight < 10 th centile. Fetal echocardiography was performed at 28-32 weeks to assess cardiac dimensions, geometry and function. ART fetuses had dilated atria (mean left atrium-to-heart area ratio: controls, 15 ± 2.7%; ART-AGA, 18 ± 4.1%; Spont-SGA, 14 ± 3.7%) and more globular ventricles (left ventricular sphericity index: controls, 1.77 ± 0.2; ART-AGA, 1.68 ± 0.2; Spont-SGA, 1.72 ± 0.2), with normally sized hearts. In contrast, SGA fetuses had enlarged hearts (cardiothoracic ratio: controls, 24 ± 3%; ART-AGA, 24 ± 4%; Spont-SGA, 29 ± 6%), preserved atrial size, more globular and concentric hypertrophic ventricles (left ventricle relative wall thickness: controls, 0.48 ± 0.17; ART-AGA, 0.54 ± 0.13; Spont-SGA, 0.63 ± 0.23). Both ART and SGA fetuses had decreased longitudinal motion (tricuspid annular ring displacement: controls, 6.5 ± 0.8 mm; ART-AGA, 5.5 ± 0.7 mm; Spont-SGA, 5.9 ± 0.6 mm) and impaired relaxation (left isovolumetric relaxation time: controls, 47.0 ± 7.3 ms; ART-AGA, 50.0 ± 7.9 ms; Spont-SGA, 49.5 ± 9.3 ms). ART-SGA fetuses presented a combination of features from both ART and SGA groups. SGA and conception with ART were associated with distinct patterns of fetal cardiac remodeling, supporting the concept that they are independent causes of cardiac programming. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Cost-effectiveness analysis of a quantitative immunochemical test for colorectal cancer screening.

PubMed

Wilschut, Janneke A; Hol, Lieke; Dekker, Evelien; Jansen, Jan B; Van Leerdam, Monique E; Lansdorp-Vogelaar, Iris; Kuipers, Ernst J; Habbema, J Dik F; Van Ballegooijen, Marjolein

2011-11-01

Two European randomized trials (N = 30,000) compared guaiac fecal occult blood testing with quantitative fecal immunochemical testing (FIT) and showed better attendance rates and test characteristics for FIT. We aimed to identify the most cost-effective FIT cutoff level for referral to colonoscopy based on data from these trials and allowing for differences in screening ages. We used the validated MIcrosimulation SCreening ANalysis (MISCAN)-Colon microsimulation model to estimate costs and effects of different screening strategies for FIT cutoff levels of 50, 75, 100, 150, and 200 ng/mL hemoglobin. For each cutoff level, screening strategies were assessed with various age ranges and screening intervals. We assumed sufficient colonoscopy capacity for all strategies. At all cost levels, FIT screening was most effective with the 50 ng/mL cutoff level. The incremental cost-effectiveness ratio of biennial screening between ages 55 and 75 years using FIT at 50 ng/mL, for example, was 3900 euro per life year gained. Annual screening had an incremental cost-effectiveness ratio of 14,900 euro per life year gained, in combination with a wider age range (between ages 45 and 80 years). In the sensitivity analysis, 50 ng/mL remained the preferred cutoff level. FIT screening is more cost-effective at a cutoff level of 50 ng/mL than at higher cutoff levels. This supports the recommendation to use FIT at a cutoff level of 50 ng/mL, which is considerably lower than the values used in current practice. Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.

Safety of topical minoxidil solution: a one-year, prospective, observational study.

PubMed

Shapiro, Jerry

2003-01-01

Topical minoxidil solution (TMS) is widely used for androgenetic alopecia (AGA), and this is the first report of a large safety trial. The aim of the study was to evaluate the safety profile of TMS by comparing hospitalization and death rates among subjects using TMS with controls. Cardiovascular safety and pregnancy outcomes were evaluated, and usage patterns were described. All subjects were followed at baseline, 3, 6, 9, and 12 months. Usage patterns, pregnancy status, overnight hospital stays, and cardiovascular risk factors were evaluated. Subjects rated effectiveness of TMS in the treatment of AGA. Statistical analyses were conducted to determine if TMS was associated with an increased risk of death or hospitalization. TMS is a safe and effective treatment for AGA. There were no increases in cardiovascular events and no apparent increased risk for adverse pregnancy outcomes. This large, prospective study demonstrated the overall safety of TMS in the treatment of AGA.

One size fits one: pharmacogenetics in gastroenterology.

PubMed

Porayette, Prashanth; Flockhart, David; Gupta, Sandeep K

2014-04-01

Individual variability in response and development of adverse effects to drugs is a major challenge in clinical practice. Pharmacogenomics refers to the aspect of personalized medicine where the patient's genetic information instructs the selection and dosage of therapy while also predicting its adverse effects profile. Sequencing of the entire human genome has given us the opportunity to study commonly used drugs as well as newer therapeutic agents in a new light, opening up opportunities for better drug efficacy and decreased adverse effects. This article highlights developments in pharmacogenomics, relates these to practice of gastroenterology, and outlines roadblocks in translation of this knowledge into clinical practice. Copyright © 2014 AGA Institute. Published by Elsevier Inc. All rights reserved.

Interactions between tafenoquine and artemisinin-combination therapy partner drug in asexual and sexual stage Plasmodium falciparum.

PubMed

Kemirembe, Karen; Cabrera, Mynthia; Cui, Liwang

2017-08-01

The 8-aminoquinoline tafenoquine (TFQ), a primaquine derivative, is currently in late-stage clinical development for the radical cure of P. vivax. Here drug interactions between TFQ and chloroquine and six artemisinin-combination therapy (ACT) partner drugs in P. falciparum asexual stages and gametocytes were investigated. TFQ was mostly synergistic with the ACT-partner drugs in asexual parasites regardless of genetic backgrounds. However, at fixed ratios of 1:3, 1:1 and 3:1, TFQ only interacted synergistically with naphthoquine, pyronaridine and piperaquine in gametocytes. This study indicated that TFQ and ACT-partner drugs will likely have increased potency against asexual stages of the malaria parasites, whereas some drugs may interfere with each other against the P. falciparum gametocytes. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Androgenic alopecia is associated with less dietary soy, lower [corrected] blood vanadium and rs1160312 1 polymorphism in Taiwanese communities.

PubMed

Lai, Ching-Huang; Chu, Nain-Feng; Chang, Chi-Wen; Wang, Shu-Li; Yang, Hsin-Chou; Chu, Chi-Ming; Chang, Chu-Ting; Lin, Ming-Huang; Chien, Wu-Chien; Su, Sui-Lung; Chou, Yu-Ching; Chen, Kang-Hua; Wang, Wei-Ming; Liou, Saou-Hsing

2013-01-01

Although the genetic basis of androgenic alopecia has been clearly established, little is known about its non-genetic causes, such as environmental and lifestyle factors. This study investigated blood and urine heavy metals concentrations, environmental exposure factors, personal behaviors, dietary intakes and the genotypes of related susceptibility genes in patients with androgenic alopecia (AGA). Age, AGA level, residence area, work hours, sleep patterns, cigarette usage, alcohol consumption, betel nut usage, hair treatments, eating habits, body heavy metals concentrations and rs1998076, rs913063, rs1160312 and rs201571 SNP genotype data were collected from 354 men. Logistic regression analysis was performed to examine whether any of the factors displayed odds ratios (ORs) indicating association with moderate to severe AGA (≥ IV). Subsequently, Hosmer-Lemeshow, Nagelkerke R(2) and accuracy tests were conducted to help establish an optimal model. Moderate to severe AGA was associated with the AA genotype of rs1160312 (22.50, 95% CI 3.99-126.83), blood vanadium concentration (0.02, 95% CI 0.01-0.04), and regular consumption of soy bean drinks (0.23, 95% CI 0.06-0.85), after adjustment for age. The results were corroborated by the Hosmer-Lemeshow test (P = 0.73), Nagelkerke R(2) (0.59), accuracy test (0.816) and area under the curve (AUC; 0.90, 0.847-0.951) analysis. Blood vanadium and frequent soy bean drink consumption may provide protect effects against AGA. Accordingly, blood vanadium concentrations, the AA genotype of rs1160312 and frequent consumption of soy bean drinks are associated with AGA.

Statistical aspects of evolution under natural selection, with implications for the advantage of sexual reproduction.

PubMed

Crouch, Daniel J M

2017-10-27

The prevalence of sexual reproduction remains mysterious, as it poses clear evolutionary drawbacks compared to reproducing asexually. Several possible explanations exist, with one of the most likely being that finite population size causes linkage disequilibria to randomly generate and impede the progress of natural selection, and that these are eroded by recombination via sexual reproduction. Previous investigations have either analysed this phenomenon in detail for small numbers of loci, or performed population simulations for many loci. Here we present a quantitative genetic model for fitness, based on the Price Equation, in order to examine the theoretical consequences of randomly generated linkage disequilibria when there are many loci. In addition, most previous work has been concerned with the long-term consequences of deleterious linkage disequilibria for population fitness. The expected change in mean fitness between consecutive generations, a measure of short-term evolutionary success, is shown under random environmental influences to be related to the autocovariance in mean fitness between the generations, capturing the effects of stochastic forces such as genetic drift. Interaction between genetic drift and natural selection, due to randomly generated linkage disequilibria, is demonstrated to be one possible source of mean fitness autocovariance. This suggests a possible role for sexual reproduction in reducing the negative effects of genetic drift, thereby improving the short-term efficacy of natural selection. Copyright © 2017 Elsevier Ltd. All rights reserved.

Detection of Gene Flow from Sexual to Asexual Lineages in Thrips tabaci (Thysanoptera: Thripidae)

PubMed Central

Li, Xiao-Wei; Wang, Ping; Fail, Jozsef; Shelton, Anthony M.

2015-01-01

Populations of Thrips tabaci are known to have two sympatric but genetically isolated reproductive modes, arrhenotoky (sexual reproduction) and thelytoky (asexual reproduction). Herein, we report behavioral, ecological and genetic studies to determine whether there is gene flow between arrhenotokous and thelytokous T. tabaci. We did not detect significant preference by arrhenotokous males to mate with females of a particular reproductive mode, nor did we detect significant behavioral differences between arrhenotokous males mated with arrhenotokous or thelytokous females in their pre-copulation, copulation duration and mating frequency. Productive gene transfer resulting from the mating between the two modes was experimentally confirmed. Gene transfer from arrhenotokous T. tabaci to thelytokous T. tabaci was further validated by confirmation of the passage of the arrhenotokous male-originated nuclear gene (histone H3 gene) allele to the F2 generation. These behavioral, ecological and genetic studies confirmed gene transfer from the sexual arrhenotokous mode to the asexual thelytokous mode of T. tabaci in the laboratory. These results demonstrate that asexual T. tabaci populations may acquire genetic variability from sexual populations, which could offset the long-term disadvantage of asexual reproduction. PMID:26375283

Variation in the strength of male mate choice allows long-term coexistence of sperm-dependent asexuals and their sexual hosts.

PubMed

Mee, Jonathan A; Otto, Sarah P

2010-10-01

In several asexual taxa, reproduction requires mating with related sexual species to stimulate egg development, even though genetic material is not incorporated from the sexuals (gynogenesis). In cases in which gynogens do not invest in male function, they can potentially have a twofold competitive advantage over sexuals because the asexuals avoid the cost of producing males. If unmitigated, however, the competitive success of the asexuals would ultimately lead to their own demise, following the extinction of the sexual species that stimulate egg development. We have studied a model of mate choice among sexual individuals and asexual gynogens, where males of the sexual species preferentially mate with sexual females over gynogenetic females, to determine if such mating preferences can stably maintain both gynogenetic and sexual individuals within a community. Our model shows that stable coexistence of gynogens and their sexual hosts can occur when there is variation among males in the degree of preference for mating with sexual females and when pickier males pay a higher cost of preference. © 2010 The Author(s). Journal compilation © 2010 The Society for the Study of Evolution.

Drug Treatment for Androgenetic Alopecia: First Italian Questionnaire Survey on What Dermatologists Think about Finasteride.

PubMed

Sorbellini, Elisabetta; Pinto, Daniela; Marzani, Barbara; Rinaldi, Fabio

2018-06-01

Treatment with finasteride 1 mg/day represents the therapy of choice for androgenetic alopecia (AGA). We investigated how Italian dermatologists approach use of finasteride for treatment of AGA and common side effects reported by patients. A tablet-based survey was conducted from February 2017 to January 2018 in Italy to investigating use of 1 mg/day finasteride in the treatment of AGA. Approximately 1153 Italian dermatologists were surveyed about prescription frequency, therapy duration, treatment practices, and side effects eventually reported. Dermatologists considered treatment with 1 mg/day finasteride to be the most efficacious treatment for AGA, as reflecting by its long-term (5 years) prescription. Data on sexual side effects from our survey are in line with previous scientific evidence, especially regarding loss of libido, erectile dysfunction, and problems with ejaculation, but also in the psychological sphere and regarding physical impairments such as myalgia and loss of muscle tone. This is the first preliminary observational study on how Italian dermatologists approach use of finasteride to treat AGA. Although side effects have been reported, especially in the sexual sphere, lack of alternative treatments with the same efficacy leads dermatologists to prescribe 1 mg/day finasteride with a tendency to prolong therapy in the long term. Giuliani S.p.A.

Pancreatic cancer biology and genetics from an evolutionary perspective

PubMed Central

Makohon-Moore, Alvin; Iacobuzio-Donahue, Christine A.

2017-01-01

Cancer is an evolutionary disease, containing the hallmarks of an asexually reproducing unicellular organism subject to evolutionary paradigms. Pancreatic ductal adenocarcinoma (hereafter referred to as pancreatic cancer) is a particularly robust example of this phenomenon. Genomic features indicate that pancreatic cancer cells are selected for fitness advantages when encountering the geographic and resource-depleted constraints of the microenvironment. Phenotypic adaptations to these pressures help disseminated cells to survive in secondary sites, a major clinical problem for patients with this disease. In this Review we gather the wide-ranging aspects of pancreatic cancer research into a single concept rooted in Darwinian evolution, with the goal of identifying novel insights and opportunities for study. PMID:27444064

The Fitness Consequences of Aneuploidy Are Driven by Condition-Dependent Gene Effects

PubMed Central

Sunshine, Anna B.; Payen, Celia; Ong, Giang T.; Liachko, Ivan; Tan, Kean Ming; Dunham, Maitreya J.

2015-01-01

Aneuploidy is a hallmark of tumor cells, and yet the precise relationship between aneuploidy and a cell’s proliferative ability, or cellular fitness, has remained elusive. In this study, we have combined a detailed analysis of aneuploid clones isolated from laboratory-evolved populations of Saccharomyces cerevisiae with a systematic, genome-wide screen for the fitness effects of telomeric amplifications to address the relationship between aneuploidy and cellular fitness. We found that aneuploid clones rise to high population frequencies in nutrient-limited evolution experiments and show increased fitness relative to wild type. Direct competition experiments confirmed that three out of four aneuploid events isolated from evolved populations were themselves sufficient to improve fitness. To expand the scope beyond this small number of exemplars, we created a genome-wide collection of >1,800 diploid yeast strains, each containing a different telomeric amplicon (Tamp), ranging in size from 0.4 to 1,000 kb. Using pooled competition experiments in nutrient-limited chemostats followed by high-throughput sequencing of strain-identifying barcodes, we determined the fitness effects of these >1,800 Tamps under three different conditions. Our data revealed that the fitness landscape explored by telomeric amplifications is much broader than that explored by single-gene amplifications. As also observed in the evolved clones, we found the fitness effects of most Tamps to be condition specific, with a minority showing common effects in all three conditions. By integrating our data with previous work that examined the fitness effects of single-gene amplifications genome-wide, we found that a small number of genes within each Tamp are centrally responsible for each Tamp’s fitness effects. Our genome-wide Tamp screen confirmed that telomeric amplifications identified in laboratory-evolved populations generally increased fitness. Our results show that Tamps are mutations that produce large, typically condition-dependent changes in fitness that are important drivers of increased fitness in asexually evolving populations. PMID:26011532

Humanin Derivatives Inhibit Necrotic Cell Death in Neurons

PubMed Central

Cohen, Aviv; Lerner-Yardeni, Jenny; Meridor, David; Kasher, Roni; Nathan, Ilana; Parola, Abraham H

2015-01-01

Humanin and its derivatives are peptides known for their protective antiapoptotic effects against Alzheimer’s disease. Herein, we identify a novel function of the humanin-derivative AGA(C8R)-HNG17 (namely, protection against cellular necrosis). Necrosis is one of the main modes of cell death, which was until recently considered an unmoderated process. However, recent findings suggest the opposite. We have found that AGA(C8R)-HNG17 confers protection against necrosis in the neuronal cell lines PC-12 and NSC-34, where necrosis is induced in a glucose-free medium by either chemohypoxia or by a shift from apoptosis to necrosis. Our studies in traumatic brain injury models in mice, where necrosis is the main mode of neuronal cell death, have shown that AGA(C8R)-HNG17 has a protective effect. This result is demonstrated by a decrease in a neuronal severity score and by a reduction in brain edema, as measured by magnetic resonance imaging (MRI). An insight into the peptide’s antinecrotic mechanism was attained through measurements of cellular ATP levels in PC-12 cells under necrotic conditions, showing that the peptide mitigates a necrosis-associated decrease in ATP levels. Further, we demonstrate the peptide’s direct enhancement of the activity of ATP synthase activity, isolated from rat-liver mitochondria, suggesting that AGA(C8R)-HNG17 targets the mitochondria and regulates cellular ATP levels. Thus, AGA(C8R)-HNG17 has potential use for the development of drug therapies for necrosis-related diseases, for example, traumatic brain injury, stroke, myocardial infarction, and other conditions for which no efficient drug-based treatment is currently available. Finally, this study provides new insight into the mechanisms underlying the antinecrotic mode of action of AGA(C8R)-HNG17. PMID:26062019

Aminoglycoside antibiotics as a tool for the study of the biological role of calcium ions. Historical overview.

PubMed

Corrado, A P; de Morais, I P; Prado, W A

1989-01-01

Beginning with the pioneering work of Vital-Brazil and Corrado (1957), which suggested a possible interaction between aminoglycoside antibiotics (AGA) and calcium ions at the neuromuscular junction, the authors review the studies that demonstrated the existence of a competitive antagonism between AGA and calcium ions. In view of the low liposolubility of AGA and their inability to cross biological membranes, this antagonism seems to occur exclusively at calcium-binding sites at the level of the outer opening of calcium channels of the N-subtype, which are also the sites of interaction of omega-conotoxin. Being highly water soluble, AGA are easily removed from their binding sites with a consequent rapid reversal of their effects, a factor of primary importance to explain their wide use as tools in the pharmacological analysis of the study of the biological role of calcium ion on the membrane's outer surface. This use has advantages over the use of inorganic di- and trivalent cations such as Mg2+, Mn2+, Cd2+, Ni2+, La3+, etc., since the latter, though they are considered to be the most specific competitive antagonists of calcium ions, may induce biphasic effects due to their ability to cross the membranes and replace calcium and/or increase intracellular calcium concentration. The performance of AGA is also superior when compared with the so-called "specific" organic calcium antagonists--verapamil and nifedipine derivatives--since the latter, in addition to inducing possible biphasic effects, antagonize calcium in a non-competitive manner. Finally, the authors remark that AGA-Ca2+ antagonism relevance is not limited only to basic aspects and that it may have therapeutic implications since it provides alternatives for reducing the toxic adverse effects of this important group of antibiotics.

Carboxyhemoglobin levels in umbilical cord blood of women with pre-eclampsia and intrauterine growth restriction.

PubMed

Yusuf, Kamran; Kamaluddeen, Majeeda; Wilson, R Douglas; Akierman, Albert

2012-11-01

Pre-eclampsia (PE) and intrauterine growth restriction (IUGR) are associated with abnormal placentation. Heme oxygenase (HO) and carbon monoxide (CO) are involved in normal placental development and function and vasomotor control in the placenta. The objective of our study was to measure CO levels, as assessed by carboxyhemoglobin (COHb) levels in the umbilical cord arterial blood of women with PE, normotensive IUGR (<10th percentile for birth weight), and normotensive pregnancies with appropriate-for-gestational age (AGA) infants. We prospectively analyzed COHb levels in the umbilical arterial blood of women with PE, normotensive IUGR, and normotensive AGA pregnancies. Exclusion criteria included cigarette smoke exposure, hemolytic disorders, a positive direct anti-globulin test, chronic hypertension, fever, and any significant medical illness. COHb levels were measured using the ABL 725 blood gas analyzer. There were 41 women in the normotensive AGA group, 42 in the PE group, and 36 in the normotensive IUGR group. Maternal age, mode of delivery, gravidity, parity, and gender of the infants were similar in the three groups. Gestational age and birth weight were significantly higher in the normotensive AGA group compared with the other two groups. COHb levels were significantly lower in the PE group compared with the normotensive AGA group (0.38±0.06% vs. 0.77±0.11%, P<0.05). COHb levels, although lower in the normotensive IUGR group compared with the normotensive AGA group, did not reach statistical significance. Our data suggests the HO-CO system may have a role in the pathogenesis of PE. We also, for the first time, provide information on umbilical arterial COHb levels in normotensive IUGR pregnancies.

Phenotypic plasticity in reproductive effort: malaria parasites respond to resource availability

PubMed Central

Repton, Charlotte; O'Donnell, Aidan J.; Schneider, Petra; Reece, Sarah E.

2017-01-01

The trade-off between survival and reproduction is fundamental in the life history of all sexually reproducing organisms. This includes malaria parasites, which rely on asexually replicating stages for within-host survival and on sexually reproducing stages (gametocytes) for between-host transmission. The proportion of asexual stages that form gametocytes (reproductive effort) varies during infections—i.e. is phenotypically plastic—in response to changes in a number of within-host factors, including anaemia. However, how the density and age structure of red blood cell (RBC) resources shape plasticity in reproductive effort and impacts upon parasite fitness is controversial. Here, we examine how and why the rodent malaria parasite Plasmodium chabaudi alters its reproductive effort in response to experimental perturbations of the density and age structure of RBCs. We show that all four of the genotypes studied increase reproductive effort when the proportion of RBCs that are immature is elevated during host anaemia, and that the responses of the genotypes differ. We propose that anaemia (counterintuitively) generates a resource-rich environment in which parasites can afford to allocate more energy to reproduction (i.e. transmission) and that anaemia also exposes genetic variation to selection. From an applied perspective, adaptive plasticity in parasite reproductive effort could explain the maintenance of genetic variation for virulence and why anaemia is often observed as a risk factor for transmission in human infections. PMID:28768894

EVALUATION OF THE RELATIONSHIP BETWEEN ANDROGENETIC ALOPECIA AND DEMODEX INFESTATION

PubMed Central

Zari, Javidi; Abdolmajid, Fata; Masood, Maleki; Vahid, Mashayekhi; Yalda, Nahidi

2008-01-01

Introduction: Androgenetic alopecia (AGA) is one of the most common dermatologic disorders with a multifactorial etiology. Inflammatory activators such as Demodex infestation may play a role in the pathogenesis of some cases of androgenetic alopecia that do not respond to common treatments such as minoxidil and finasteride. The goal of this study is to evaluate the relationship between Demodex infestation and AGA. Materials and Methods: In this case-control study, 41 patients with AGA referred to the Dermatology Clinic of Imam Reza Hospital and 33 healthy individuals were evaluated as control. All of them were between 20 and 40 years old men. In order to identify Demodex infestation they were referred to the Parasitology laboratory. Results: Demodex was detected in 19.5% of patients and 15.2% of controls; therefore, there was no significant relationship between them statistically (P = 0.0787). Most of patients (85.4%) had greasy hair. The most common pattern of baldness was II degree in Hamilton scale. Conclusion: There is no relation between AGA and Demodex. PMID:19881989

Effect of the SOS response on the mean fitness of unicellular populations: a quasispecies approach.

PubMed

Kama, Amit; Tannenbaum, Emmanuel

2010-11-30

The goal of this paper is to develop a mathematical model that analyzes the selective advantage of the SOS response in unicellular organisms. To this end, this paper develops a quasispecies model that incorporates the SOS response. We consider a unicellular, asexually replicating population of organisms, whose genomes consist of a single, double-stranded DNA molecule, i.e. one chromosome. We assume that repair of post-replication mismatched base-pairs occurs with probability , and that the SOS response is triggered when the total number of mismatched base-pairs is at least . We further assume that the per-mismatch SOS elimination rate is characterized by a first-order rate constant . For a single fitness peak landscape where the master genome can sustain up to mismatches and remain viable, this model is analytically solvable in the limit of infinite sequence length. The results, which are confirmed by stochastic simulations, indicate that the SOS response does indeed confer a fitness advantage to a population, provided that it is only activated when DNA damage is so extensive that a cell will die if it does not attempt to repair its DNA.

Genetic Diversity in the Interference Selection Limit

PubMed Central

Good, Benjamin H.; Walczak, Aleksandra M.; Neher, Richard A.; Desai, Michael M.

2014-01-01

Pervasive natural selection can strongly influence observed patterns of genetic variation, but these effects remain poorly understood when multiple selected variants segregate in nearby regions of the genome. Classical population genetics fails to account for interference between linked mutations, which grows increasingly severe as the density of selected polymorphisms increases. Here, we describe a simple limit that emerges when interference is common, in which the fitness effects of individual mutations play a relatively minor role. Instead, similar to models of quantitative genetics, molecular evolution is determined by the variance in fitness within the population, defined over an effectively asexual segment of the genome (a “linkage block”). We exploit this insensitivity in a new “coarse-grained” coalescent framework, which approximates the effects of many weakly selected mutations with a smaller number of strongly selected mutations that create the same variance in fitness. This approximation generates accurate and efficient predictions for silent site variability when interference is common. However, these results suggest that there is reduced power to resolve individual selection pressures when interference is sufficiently widespread, since a broad range of parameters possess nearly identical patterns of silent site variability. PMID:24675740

[Relationship of plasma ghrelin, IGF-1 and insulin with the growth and development of 2 -7 year-old children with small for gestational age at birth].

PubMed

Cheng, Yaying; Song, Guangyao; Zhou, Lixia; Cai, Baoping; Zhao, Xiumian; Yin, Jianying

2012-01-01

To explore the relationship of Ghrelin, insulin-like growth factor-1 (IGF-1) and insulin with the growth and development of 2 -7 year-old children with small for gestational age (SGA) at birth. The levels of ghrelin, IGF-1, IGFBP-3, insulin and glucose were measured in the children with preterm SGA and term SGA and compared with the children with preterm appropriate for gestational age (AGA) and term AGA. The correlation of ghrelin with IGF-1, IGFBP-3 and insulin was analyzed. Plasma ghrelin in preterm SGA was higher than that in term SGA (P < 0.05), and there was no significant difference between preterm SGA and preterm AGA (P > 0.05). Plasma ghrelin in preterm AGA and term SGA was higher than that in term AGA (P < 0.05, P < 0.01 respectively). Serum IGF-1 and IGFBP-3 in preterm SGA were lower than those in term SGA (P < 0.05 for all) and serum IGF-1 and IGFBP-3 in preterm AGA were much lower than those in term AGA (P < 0.0001 for all). The level of serum insulin was the highest in term SGA. The trend of insulin resistance index (IRI) was similar to insulin. There were negative correlations of ghrelin with other indexes (weight SDS, IGF-1, IGFBP-3, insulin and IRI) in preterm SGA and term SGA (in preterm SGA r = -0.683, P < 0.002; r = -0.749, P < 0.001; r = -0.828, P < 0.001; r = -0.694, P < 0.005; r = -0.822, P < 0.001; in term SGA r = -0.792, P < 0.001; r = -0.707, P < 0.002; r = -0.615, P < 0.01; r = -0.648, P < 0.005; r = -0.679, P < 0.005). Ghrelin is involved in the regulation of growth and development of preterm and SGA children, regardless of the magnitude of their catch up growth. As a re-regulatory factor to insulin, ghrelin regulates the energy metabolism in a form of negative feedback.

Self-Organized Criticality in an Asexual Model?

NASA Astrophysics Data System (ADS)

Chisholm, Colin; Jan, Naeem; Gibbs, Peter; Erzan, Ayşe.

Recent work has shown that the distribution of steady state mutations for an asexual ``bacteria'' model has features similar to that seen in Self-Organized Critical (SOC) sandpile model of Bak et al. We investigate this coincidence further and search for ``self-organized critical'' state for bacteria but instead find that the SOC sandpile critical behavior is very sensitive; critical behavior is destroyed with small perturbations effectively when the absorption of sand is introduced. It is only in the limit when the length of the genome of the bacteria tends to infinity that SOC properties are recovered for the asexual model.

Use of videos for Distribution Construction and Maintenance (DC M) training

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, G.M.

This paper presents the results of a survey taken among members of the American Gas Association (AGA)'s Distribution Construction and Maintenance (DC M) committee to gauge the extent, sources, mode of use, and degree of satisfaction with videos as a training aid in distribution construction and maintenance skills. Also cites AGA Engineering Technical Note, DCM-88-3-1, as a catalog of the videos listed by respondents to the survey. Comments on the various sources of training videos and the characteristics of videos from each. Conference presentation included showing of a sampling of video segments from these various sources. 1 fig.

Novel Therapeutic Strategy for the Prevention of Bone Fractures

DTIC Science & Technology

2013-06-01

AGA GAG GGA GAT GCT CAG TGT TGG M32599 18S AGT GCG GGT CAT AAG CTT GC GGG CCT CAC TAA AC CAT CCA V00851 β-actin GTT TGA GAC CTT CAA CAC CCC GTG ...GCC ATC TCC TGC TCG AAG TC Meredith et al 2011* Mstn ACT GGA CCT CTC GAT AGA ACA CTC ACT TAG TGC TGT GTG TGT GGA GAT NM_010834.2 IGF-1 CAG...ACA GGA GCC CAG GAA AG AAG TGC CGT ATC CCA GAG GA NM_184052 MHC ACA GTC AGA GGT GTG ACTC AGC CG CCG ACT TGC GGA GGA AAG GTG C NM_001099635 Murf1

Novel Therapeutic Strategy for the Prevention of Bone Fractures

DTIC Science & Technology

2014-08-01

GAC CTT CAA CAC CCC GTG GCC ATC TCC TGC TCG AAG TC Meredith et al 2011* Mstn ACT GGA CCT CTC GAT AGA ACA CTC ACT TAG TGC TGT GTG TGT GGA GAT...NM_010834.2 IGF-1 CAG ACA GGA GCC CAG GAA AG AAG TGC CGT ATC CCA GAG GA NM_184052 MHC ACA GTC AGA GGT GTG ACTC AGC CG CCG ACT TGC GGA GGA AAG GTG C...AGC AGA GA TGA GTG CCT GCG GTA CAG AT NM_007553.2 RUNX-2 GGA AAG GCA CTG ACT GAC CTA ACA AAT TCT AAG CTT GGG AGG A NM_009820 Osx ACT ACC CAC CCT TCC

Sex and the Imperfect Fungi.

PubMed

Dyer, Paul S; Kück, Ulrich

2017-06-01

Approximately 20% of species in the fungal kingdom are only known to reproduce by asexual means despite the many supposed advantages of sexual reproduction. However, in recent years, sexual cycles have been induced in a series of emblematic "asexual" species. We describe how these discoveries were made, building on observations of evidence for sexual potential or "cryptic sexuality" from population genetic analyses; the presence, distribution, and functionality of mating-type genes; genome analyses revealing the presence of genes linked to sexuality; the functionality of sex-related genes; and formation of sex-related developmental structures. We then describe specific studies that led to the discovery of mating and sex in certain Candida , Aspergillus , Penicillium , and Trichoderma species and discuss the implications of sex including the beneficial exploitation of the sexual cycle. We next consider whether there might be any truly asexual fungal species. We suggest that, although rare, imperfect fungi may genuinely be present in nature and that certain human activities, combined with the genetic flexibility that is a hallmark of the fungal kingdom, might favor the evolution of asexuality under certain conditions. Finally, we argue that fungal species should not be thought of as simply asexual or sexual, but rather as being composed of isolates on a continuum of sexual fertility.

Spermatozoa Production by Triploid Males in the New Zealand Freshwater Snail Potamopyrgus antipodarum

PubMed Central

Soper, D.M.; Neiman, M.; Savytskyy, O.P.; Zolan, M.E.; Lively, C.M.

2013-01-01

Asexual lineages derived from dioecious taxa are typically assumed to be all female. Even so, asexual females from a variety of animal taxa occasionally produce males. The existence of these males sets the stage for potential gene flow across asexual lineages as well as between sexual and asexual lineages. A recent study showed that asexual triploid female Potamopyrgus antipodarum, a New Zealand freshwater snail often used as a model to study sexual reproduction, occasionally produce triploid male offspring. Here, we show that these triploid male P. antipodarum 1) have testes that produce morphologically normal sperm, 2) make larger sperm cells that contain more nuclear DNA than the sperm produced by diploid sexual males, and 3) produce sperm that range in DNA content from haploid to diploid, and are often aneuploid. Analysis of meiotic chromosomes of triploid males showed that aberrant pairing during prophase I likely accounts for the high variation in DNA content among sperm. These results indicate that triploid male P. antipodarum produce sperm, but the extent to which these sperm are able to fertilize female ova remains unclear. Our results also suggest that the general assumption of sterility in triploid males should be more closely examined in other species in which such males are occasionally produced. PMID:24307744

Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elements

PubMed Central

Gogarten, J Peter; Hilario, Elena

2006-01-01

Self splicing introns and inteins that rely on a homing endonuclease for propagation are parasitic genetic elements. Their life-cycle and evolutionary fate has been described through the homing cycle. According to this model the homing endonuclease is selected for function only during the spreading phase of the parasite. This phase ends when the parasitic element is fixed in the population. Upon fixation the homing endonuclease is no longer under selection, and its activity is lost through random processes. Recent analyses of these parasitic elements with functional homing endonucleases suggest that this model in its most simple form is not always applicable. Apparently, functioning homing endonuclease can persist over long evolutionary times in populations and species that are thought to be asexual or nearly asexual. Here we review these recent findings and discuss their implications. Reasons for the long-term persistence of a functional homing endonuclease include: More recombination (sexual and as a result of gene transfer) than previously assumed for these organisms; complex population structures that prevent the element from being fixed; a balance between active spreading of the homing endonuclease and a decrease in fitness caused by the parasite in the host organism; or a function of the homing endonuclease that increases the fitness of the host organism and results in purifying selection for the homing endonuclease activity, even after fixation in a local population. In the future, more detailed studies of the population dynamics of the activity and regulation of homing endonucleases are needed to decide between these possibilities, and to determine their relative contributions to the long term survival of parasitic genes within a population. Two outstanding publications on the amoeba Naegleria group I intron (Wikmark et al. BMC Evol Biol 2006, 6:39) and the PRP8 inteins in ascomycetes (Butler et al.BMC Evol Biol 2006, 6:42) provide important stepping stones towards integrated studies on how these parasitic elements evolve through time together with, or despite, their hosts. PMID:17101053

Timing of host feeding drives rhythms in parasite replication

PubMed Central

Cumnock, Katherine; Schneider, David; Subudhi, Amit; Savill, Nicholas J.

2018-01-01

Circadian rhythms enable organisms to synchronise the processes underpinning survival and reproduction to anticipate daily changes in the external environment. Recent work shows that daily (circadian) rhythms also enable parasites to maximise fitness in the context of ecological interactions with their hosts. Because parasite rhythms matter for their fitness, understanding how they are regulated could lead to innovative ways to reduce the severity and spread of diseases. Here, we examine how host circadian rhythms influence rhythms in the asexual replication of malaria parasites. Asexual replication is responsible for the severity of malaria and fuels transmission of the disease, yet, how parasite rhythms are driven remains a mystery. We perturbed feeding rhythms of hosts by 12 hours (i.e. diurnal feeding in nocturnal mice) to desynchronise the host’s peripheral oscillators from the central, light-entrained oscillator in the brain and their rhythmic outputs. We demonstrate that the rhythms of rodent malaria parasites in day-fed hosts become inverted relative to the rhythms of parasites in night-fed hosts. Our results reveal that the host’s peripheral rhythms (associated with the timing of feeding and metabolism), but not rhythms driven by the central, light-entrained circadian oscillator in the brain, determine the timing (phase) of parasite rhythms. Further investigation reveals that parasite rhythms correlate closely with blood glucose rhythms. In addition, we show that parasite rhythms resynchronise to the altered host feeding rhythms when food availability is shifted, which is not mediated through rhythms in the host immune system. Our observations suggest that parasites actively control their developmental rhythms. Finally, counter to expectation, the severity of disease symptoms expressed by hosts was not affected by desynchronisation of their central and peripheral rhythms. Our study at the intersection of disease ecology and chronobiology opens up a new arena for studying host-parasite-vector coevolution and has broad implications for applied bioscience. PMID:29481559

Fashionably late partners have more fruitful encounters: Impact of the timing of co-infection and pathogenicity on sexual reproduction in Zymoseptoria tritici.

PubMed

Suffert, Frédéric; Delestre, Ghislain; Carpentier, Florence; Gazeau, Gwilherm; Walker, Anne-Sophie; Gélisse, Sandrine; Duplaix, Clémentine

2016-07-01

The wheat pathogen Zymoseptoria tritici is a relevant fungal model organism for investigations of the epidemiological determinants of sexual reproduction. The objective of this experimental study was to determine which intrinsic factors, including parental fitness and timing conditions of infection, affect the numbers of ascospores produced. We first performed 28 crosses on adult wheat plants in semi-controlled conditions, with 10 isolates characterized for their fitness traits. We validated the efficiency of the crossing method, opening up new perspectives for epidemiological studies. We found that the ability to reproduce sexually was determined, at least partly, by the parental genotypes. We also found that the number of ascospores released was correlated with the mean size of the sporulating lesions of the parental isolates on the one hand, and the absolute difference in the latent periods of these isolates on the other. No functional trade-off between the two modes of reproduction in Z. tritici was revealed: there was no adaptive compromise between pathogenicity (asexual multiplication on leaves) and transmission (intensity of sexual reproduction on wheat debris). Moreover, a few days' difference in the latent periods of the two parental isolates, such that one progressed more rapidly in the host tissue than the other, seemed to be slightly beneficial to ascosporogenesis. This may be because the first parental isolate breaks down host defenses, thereby facilitating infection for the other parental isolate. However, a larger difference (a few weeks), generated by leaving two to three weeks between the inoculations of the plant with the parental isolates, was clearly detrimental to ascosporogenesis. In this case, the host tissues were likely colonized by the first isolate, leaving less host resources available for the second, consistent with a competition effect during the asexual stage. Copyright © 2016 Elsevier Inc. All rights reserved.

A novel base change leading to Hb Vanderbilt [β89(F5)Ser→Arg, AGT>AGA].

PubMed

Goodyer, Matthew J; Elhassadi, Ezzat I; Percy, Melanie J; McMullin, Mary F

2011-01-01

We describe a high oxygen affinity hemoglobin (Hb) variant (Hb Vanderbilt) as a result of a heterozygous novel base change from T to A at codon 89 (AGT>AGA) leading to an amino acid change from serine to arginine.

Different long-term response to growth hormone therapy in small- versus appropriate-for-gestational-age children with growth hormone deficiency.

PubMed

Meazza, Cristina; Pagani, Sara; Pietra, Benedetta; Tinelli, Carmine; Calcaterra, Valeria; Bozzola, Elena; Bozzola, Mauro

2013-01-01

The role of birth weight on growth hormone (GH) therapy response in GH-deficient (GHD) children has not been fully elucidated. Therefore, we examined the growth of 23 small-for-gestational-age GHD children (SGA-GHD, 11 females and 12 males), 26 appropriate-for-gestational-age GHD children (AGA-GHD, 11 females and 15 males) during the first 5 years of GH therapy and that of 22 non-GH-treated SGA children (12 females and 10 males). We collected height and height velocity measurements yearly. In AGA-GHD children, height was always greater than in the SGA groups and significantly increased from the fourth year of treatment. Height velocity was higher (SGA-GHD: 1.72 ± 0.30 standard deviation score, SDS, AGA-GHD: 2.67 ± 0.21 SDS; p = 0.039) in AGA-GHD children during the first year of treatment. The AGA-GHD group showed the highest percentage (52.4%) of subjects surpassing mid-parental height and the greatest height gain after 5 years of follow-up. Our results show that birth size is an important factor affecting the response to GH therapy in GHD children during the first 5 years of treatment. The paediatric endocrinologist should be aware of this factor when planning the management of GHD children born SGA. Copyright © 2013 S. Karger AG, Basel.

How to infer relative fitness from a sample of genomic sequences.

PubMed

Dayarian, Adel; Shraiman, Boris I

2014-07-01

Mounting evidence suggests that natural populations can harbor extensive fitness diversity with numerous genomic loci under selection. It is also known that genealogical trees for populations under selection are quantifiably different from those expected under neutral evolution and described statistically by Kingman's coalescent. While differences in the statistical structure of genealogies have long been used as a test for the presence of selection, the full extent of the information that they contain has not been exploited. Here we demonstrate that the shape of the reconstructed genealogical tree for a moderately large number of random genomic samples taken from a fitness diverse, but otherwise unstructured, asexual population can be used to predict the relative fitness of individuals within the sample. To achieve this we define a heuristic algorithm, which we test in silico, using simulations of a Wright-Fisher model for a realistic range of mutation rates and selection strength. Our inferred fitness ranking is based on a linear discriminator that identifies rapidly coalescing lineages in the reconstructed tree. Inferred fitness ranking correlates strongly with actual fitness, with a genome in the top 10% ranked being in the top 20% fittest with false discovery rate of 0.1-0.3, depending on the mutation/selection parameters. The ranking also enables us to predict the genotypes that future populations inherit from the present one. While the inference accuracy increases monotonically with sample size, samples of 200 nearly saturate the performance. We propose that our approach can be used for inferring relative fitness of genomes obtained in single-cell sequencing of tumors and in monitoring viral outbreaks. Copyright © 2014 by the Genetics Society of America.

Quantifying the Role of Population Subdivision in Evolution on Rugged Fitness Landscapes

PubMed Central

Bitbol, Anne-Florence; Schwab, David J.

2014-01-01

Natural selection drives populations towards higher fitness, but crossing fitness valleys or plateaus may facilitate progress up a rugged fitness landscape involving epistasis. We investigate quantitatively the effect of subdividing an asexual population on the time it takes to cross a fitness valley or plateau. We focus on a generic and minimal model that includes only population subdivision into equivalent demes connected by global migration, and does not require significant size changes of the demes, environmental heterogeneity or specific geographic structure. We determine the optimal speedup of valley or plateau crossing that can be gained by subdivision, if the process is driven by the deme that crosses fastest. We show that isolated demes have to be in the sequential fixation regime for subdivision to significantly accelerate crossing. Using Markov chain theory, we obtain analytical expressions for the conditions under which optimal speedup is achieved: valley or plateau crossing by the subdivided population is then as fast as that of its fastest deme. We verify our analytical predictions through stochastic simulations. We demonstrate that subdivision can substantially accelerate the crossing of fitness valleys and plateaus in a wide range of parameters extending beyond the optimal window. We study the effect of varying the degree of subdivision of a population, and investigate the trade-off between the magnitude of the optimal speedup and the width of the parameter range over which it occurs. Our results, obtained for fitness valleys and plateaus, also hold for weakly beneficial intermediate mutations. Finally, we extend our work to the case of a population connected by migration to one or several smaller islands. Our results demonstrate that subdivision with migration alone can significantly accelerate the crossing of fitness valleys and plateaus, and shed light onto the quantitative conditions necessary for this to occur. PMID:25122220

Asexuality: an extreme variant of sexual desire disorder?

PubMed

Brotto, Lori A; Yule, Morag A; Gorzalka, Boris B

2015-03-01

Human asexuality is defined as a lack of sexual attraction to anyone or anything. Various theories have been proposed to explain how asexuality should best be classified, and some have maintained that asexuality is an extreme variant of hypoactive sexual desire disorder (HSDD)-a sexual dysfunction characterized by a lack of interest in sex and significant distress. To date, this has never been empirically examined. Using measures of sexual desire and behavior, sex-related distress, personality, and psychopathology, the aim of the current study was to compare individuals scoring above the cutoff for asexuality identification (AIS >40) (n = 192) to sexual individuals (n = 231). The sexual group was further divided into a control group (n = 122), a HSDD group (n = 50), and a group with symptoms of low desire that were nondistressing (n = 59). Analyses were controlled for age. Individuals in the AIS >40 group had a greater likelihood of never previously engaging in sexual intercourse, fantasies, or kissing and petting than all other groups and a lower likelihood of experiencing sex-related distress than those with HSDD. For women, those in the HSDD and AIS >40 groups had significantly lower desire than the subclinical HSDD and control groups. Men in the AIS >40 group had significantly lower desire than the other three groups. Symptoms of depression were highest among those with subclinical HSDD and HSDD, whereas there were no group differences on alexithymia or desirable responding. A binary logistic regression indicated that relationship status (long-term dating/married), sexual desire, sex-related distress, and lower alexithymia scores were the best predictors of group membership (HSDD vs. AIS >40). Taken together, these results challenge the speculation that asexuality should be classified as a sexual dysfunction of low desire. © 2014 International Society for Sexual Medicine.

Impact of three phthalate esters on the sexual reproduction of the Monogonont rotifer, Brachionus calyciflorus.

PubMed

Cruciani, V; Iovine, C; Thomé, J-P; Joaquim-Justo, C

2016-01-01

Phthalate esters are widespread contaminants that can cause endocrine disruption in vertebrates. Studies showed that molecules with hormonal activities in vertebrates and invertebrates can affect asexual and sexual reproduction in rotifers. We investigated the impact of di-hexylethyl phthalate (DEHP), di-butyl phthalate (DBP) and butylbenzyl phthalate (BBP), on the asexual and sexual reproduction of the freshwater monogonont rotifer Brachionus calyciflorus in order to determine a potential environmental risk for sexual reproduction. We observed that DEHP has no significant impact on both asexual and sexual reproduction up to 2 mg/L. DBP has a positive effect on asexual reproduction at concentrations from 0.05 to 1 mg/L, but depresses it at 2 mg/L. Sexual reproduction is only affected at 2 mg/L and the impact observed is negative. BBP displayed a negative impact on both asexual and sexual reproduction at 1 and 2 mg/L. However we showed that the impacts of BBP on mixis and fertilization rates observed are due to the decrease in population growth rates at these concentrations and not to a direct impact of BBP on the mixis and the fertilization processes. Our results show that sexual reproduction in B. calyciflorus is not more sensitive than asexual reproduction to any of the substances tested which indicates the mode of action of these molecules is related to general toxicity and not to an interference with potential endocrine regulation of sexual reproduction. Comparison of effect concentrations and surface water contamination by phthalate esters suggests these compounds do not constitute a risk for primary consumers in these environments.

On the Genealogy of Asexual Diploids

NASA Astrophysics Data System (ADS)

Lam, Fumei; Langley, Charles H.; Song, Yun S.

Given molecular genetic data from diploid individuals that, at present, reproduce mostly or exclusively asexually without recombination, an important problem in evolutionary biology is detecting evidence of past sexual reproduction (i.e., meiosis and mating) and recombination (both meiotic and mitotic). However, currently there is a lack of computational tools for carrying out such a study. In this paper, we formulate a new problem of reconstructing diploid genealogies under the assumption of no sexual reproduction or recombination, with the ultimate goal being to devise genealogy-based tools for testing deviation from these assumptions. We first consider the infinite-sites model of mutation and develop linear-time algorithms to test the existence of an asexual diploid genealogy compatible with the infinite-sites model of mutation, and to construct one if it exists. Then, we relax the infinite-sites assumption and develop an integer linear programming formulation to reconstruct asexual diploid genealogies with the minimum number of homoplasy (back or recurrent mutation) events. We apply our algorithms on simulated data sets with sizes of biological interest.

[Morphofunctional organization of reserve stem cells providing for asexual and sexual reproduction of invertebrates].

PubMed

Isaeva, V V; Akhmadieva, A V; Aleksandriova, Ia N; Shukaliuk, A I

2009-01-01

Published and original data indicating evolutionary conservation of the morphofunctional organization of reserve stem cells providing for asexual and sexual reproduction of invertebrates are reviewed. Stem cells were studied in representatives of five animal types: archeocytes in sponge Oscarella malakhovi (Porifera), large interstitial cells in colonial hydroid Obelia longissima (Cnidaria), neoblasts in an asexual race of planarian Girardia tigrina (Platyhelmintes), stem cells in colonial rhizocephalans Peltogasterella gracilis, Polyascus polygenea, and Thylacoplethus isaevae (Arthropoda), and colonial ascidian Botryllus tuberatus (Chordata). Stem cells in animals of such diverse taxa feature the presence of germinal granules, are positive for proliferating cell nuclear antigen, demonstrate alkaline phosphatase activity (at marker of embryonic stem cells and primary germ cells in vertebrates), and rhizocephalan stem cells express the vasa-like gene (such genes are expressed in germline cells of different metazoans). The self-renewing pool of stem cells is the cellular basis of the reproductive strategy including sexual and asexual reproduction.

Sex as a strategy against rapidly evolving parasites

PubMed Central

Tinkler, Shona K.; Tinsley, Matthew C.

2016-01-01

Why is sex ubiquitous when asexual reproduction is much less costly? Sex disrupts coadapted gene complexes; it also causes costs associated with mate finding and the production of males who do not themselves bear offspring. Theory predicts parasites select for host sex, because genetically variable offspring can escape infection from parasites adapted to infect the previous generations. We examine this using a facultative sexual crustacean, Daphnia magna, and its sterilizing bacterial parasite, Pasteuria ramosa. We obtained sexually and asexually produced offspring from wild-caught hosts and exposed them to contemporary parasites or parasites isolated from the same population one year later. We found rapid parasite adaptation to replicate within asexual but not sexual offspring. Moreover, sexually produced offspring were twice as resistant to infection as asexuals when exposed to parasites that had coevolved alongside their parents (i.e. the year two parasite). This fulfils the requirement that the benefits of sex must be both large and rapid for sex to be favoured by selection. PMID:28003455

Sex as a strategy against rapidly evolving parasites.

PubMed

Auld, Stuart K J R; Tinkler, Shona K; Tinsley, Matthew C

2016-12-28

Why is sex ubiquitous when asexual reproduction is much less costly? Sex disrupts coadapted gene complexes; it also causes costs associated with mate finding and the production of males who do not themselves bear offspring. Theory predicts parasites select for host sex, because genetically variable offspring can escape infection from parasites adapted to infect the previous generations. We examine this using a facultative sexual crustacean, Daphnia magna, and its sterilizing bacterial parasite, Pasteuria ramosa We obtained sexually and asexually produced offspring from wild-caught hosts and exposed them to contemporary parasites or parasites isolated from the same population one year later. We found rapid parasite adaptation to replicate within asexual but not sexual offspring. Moreover, sexually produced offspring were twice as resistant to infection as asexuals when exposed to parasites that had coevolved alongside their parents (i.e. the year two parasite). This fulfils the requirement that the benefits of sex must be both large and rapid for sex to be favoured by selection. © 2016 The Author(s).

Population genomics reveals the origin and asexual evolution of human infective trypanosomes

PubMed Central

Weir, William; Capewell, Paul; Foth, Bernardo; Clucas, Caroline; Pountain, Andrew; Steketee, Pieter; Veitch, Nicola; Koffi, Mathurin; De Meeûs, Thierry; Kaboré, Jacques; Camara, Mamadou; Cooper, Anneli; Tait, Andy; Jamonneau, Vincent; Bucheton, Bruno; Berriman, Matt; MacLeod, Annette

2016-01-01

Evolutionary theory predicts that the lack of recombination and chromosomal re-assortment in strictly asexual organisms results in homologous chromosomes irreversibly accumulating mutations and thus evolving independently of each other, a phenomenon termed the Meselson effect. We apply a population genomics approach to examine this effect in an important human pathogen, Trypanosoma brucei gambiense. We determine that T.b. gambiense is evolving strictly asexually and is derived from a single progenitor, which emerged within the last 10,000 years. We demonstrate the Meselson effect for the first time at the genome-wide level in any organism and show large regions of loss of heterozygosity, which we hypothesise to be a short-term compensatory mechanism for counteracting deleterious mutations. Our study sheds new light on the genomic and evolutionary consequences of strict asexuality, which this pathogen uses as it exploits a new biological niche, the human population. DOI: http://dx.doi.org/10.7554/eLife.11473.001 PMID:26809473

Picturing space for lesbian nonsexualities: rethinking sex-normative commitments through The Kids Are All Right (2010).

PubMed

Gupta, Kristina

2013-01-01

This article examines representations of lesbian nonsexuality in the film The Kids Are All Right and in responses to the film by feminist and queer scholars. In some moments, the film offers a limited endorsement of lesbian nonsexuality, placing pressure on the category lesbian to include nonsexuality and asexuality. However, in their responses to the film, many feminist and queer scholars rejected nonsexuality as an aspect of lesbian experience, placing pressure on the category lesbian to exclude nonsexual and asexual women. Asexual activism challenges scholars to question their sex-normative commitments and to keep the category lesbian open and flexible.

Parasites in sexual and asexual mollies (Poecilia, Poeciliidae, Teleostei): a case for the Red Queen?

PubMed Central

Tobler, Michael; Schlupp, Ingo

2005-01-01

The maintenance of sexual reproduction in the face of its supposed costs is a major paradox in evolutionary biology. The Red Queen hypothesis, which states that sex is an adaptation to fast-evolving parasites, is currently one of the most recognized explanations for the ubiquity of sex and predicts that asexual lineages should suffer from a higher parasite load if they coexist with closely related sexuals. We tested this prediction using four populations of the sexual fish species Poecilia latipinna and its asexual relative Poecilia formosa. Contrary to expectation, no differences in parasite load could be detected between the two species. PMID:17148156

Clustering and phase transitions on a neutral landscape

NASA Astrophysics Data System (ADS)

Scott, Adam D.; King, Dawn M.; Marić, Nevena; Bahar, Sonya

2013-06-01

Recent computational studies have shown that speciation can occur under neutral conditions, i.e., when the simulated organisms all have identical fitness. These works bear comparison with mathematical studies of clustering on neutral landscapes in the context of branching and coalescing random walks. Here, we show that sympatric clustering/speciation can occur on a neutral landscape whose dimensions specify only the simulated organisms’ phenotypes. We demonstrate that clustering occurs not only in the case of assortative mating, but also in the case of asexual fission; it is not observed in the control case of random mating. We find that the population size and the number of clusters undergo a second-order non-equilibrium phase transition as the maximum mutation size is varied.

Identification of highly variable supernumerary chromosome segments in an asexual pathogen

USDA-ARS?s Scientific Manuscript database

Supernumerary chromosome segments are known to harbor different transposons from their essential counterparts. The aim of this study was to investigate the role of transposons in the origin and evolution of supernumerary segments in the asexual fungal pathogen Fusariumvirguliforme. We compared the g...

Loss of Sexual Reproduction and Dwarfing in a Small Metazoan

PubMed Central

Stelzer, Claus-Peter; Schmidt, Johanna; Wiedlroither, Anneliese; Riss, Simone

2010-01-01

Background Asexuality has major theoretical advantages over sexual reproduction, yet newly formed asexual lineages rarely endure. The success, or failure, of such lineages is affected by their mechanism of origin, because it determines their initial genetic makeup and variability. Most previously described mechanisms imply that asexual lineages are randomly frozen subsamples of a sexual population. Methodology/Principal Findings We found that transitions to obligate parthenogenesis (OP) in the rotifer Brachionus calyciflorus, a small freshwater invertebrate which normally reproduces by cyclical parthenogenesis, were controlled by a simple Mendelian inheritance. Pedigree analysis suggested that obligate parthenogens were homozygous for a recessive allele, which caused inability to respond to the chemical signals that normally induce sexual reproduction in this species. Alternative mechanisms, such as ploidy changes, could be ruled out on the basis of flow cytometric measurements and genetic marker analysis. Interestingly, obligate parthenogens were also dwarfs (approximately 50% smaller than cyclical parthenogens), indicating pleiotropy or linkage with genes that strongly affect body size. We found no adverse effects of OP on survival or fecundity. Conclusions/Significance This mechanism of inheritance implies that genes causing OP may evolve within sexual populations and remain undetected in the heterozygous state long before they get frequent enough to actually cause a transition to asexual reproduction. In this process, genetic variation at other loci might become linked to OP genes, leading to non-random associations between asexuality and other phenotypic traits. PMID:20862222

Genetics and other factors in the aetiology of female pattern hair loss.

PubMed

Redler, Silke; Messenger, Andrew G; Betz, Regina C

2017-06-01

Pattern hair loss is the most common form of hair loss in both women and men. Male pattern hair loss, also termed male androgenetic alopecia (M-AGA), is an androgen-dependent trait that is predominantly genetically determined. Androgen-mediated mechanisms are probably involved in female pattern hair loss (FPHL) in some women but the evidence is less strong than in M-AGA; other non-androgenic pathways, including environmental influences, may contribute to the aetiology. Genome-wide association studies have identified several genetic loci for M-AGA and have provided better insight into the underlying biology. However, the role of heritable factors in Female Pattern Hair Loss (FPHL) is largely unknown. Recently published studies have been restricted to candidate gene approaches and could not clearly identify any susceptibility locus/gene for FPHL but suggest that the aetiology differs substantially from that of M-AGA. Hypotheses about possible pathomechanisms of FPHL as well as the results of the genetic studies performed to date are summarized. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Sex versus asex: An analysis of the role of variance conversion.

PubMed

Lewis-Pye, Andrew E M; Montalbán, Antonio

2017-04-01

The question as to why most complex organisms reproduce sexually remains a very active research area in evolutionary biology. Theories dating back to Weismann have suggested that the key may lie in the creation of increased variability in offspring, causing enhanced response to selection. Under appropriate conditions, selection is known to result in the generation of negative linkage disequilibrium, with the effect of recombination then being to increase genetic variance by reducing these negative associations between alleles. It has therefore been a matter of significant interest to understand precisely those conditions resulting in negative linkage disequilibrium, and to recognise also the conditions in which the corresponding increase in genetic variation will be advantageous. Here, we prove rigorous results for the multi-locus case, detailing the build up of negative linkage disequilibrium, and describing the long term effect on population fitness for models with and without bounds on fitness contributions from individual alleles. Under the assumption of large but finite bounds on fitness contributions from alleles, the non-linear nature of the effect of recombination on a population presents serious obstacles in finding the genetic composition of populations at equilibrium, and in establishing convergence to those equilibria. We describe techniques for analysing the long term behaviour of sexual and asexual populations for such models, and use these techniques to establish conditions resulting in higher fitnesses for sexually reproducing populations. Copyright © 2017 Elsevier Inc. All rights reserved.

Fitness of RNA virus decreased by Muller's ratchet

NASA Astrophysics Data System (ADS)

Chao, Lin

1990-11-01

WHY sex exists remains an unsolved problem in biology1-3. If mutations are on the average deleterious, a high mutation rate can account for the evolution of sex4. One form of this mutational hypothesis is Muller's ratchet5,6. If the mutation rate is high, mutation-free individuals become rare and they can be lost by genetic drift in small populations. In asexual populations, as Muller5 noted, the loss is irreversible and the load of deleterious mutations increases in a ratchet-like manner with the successive loss of the least-mutated individuals. Sex can be advantageous because it increases the fitness of sexual populations by re-creating mutation-free individuals from mutated individuals and stops (or slows) Muller's ratchet. Although Muller's ratchet is an appealing hypothesis, it has been investigated and documented experimentally in only one group of organisms-ciliated protozoa2. I initiated a study to examine the role of Muller's ratchet on the evolution of sex in RNA viruses and report here a significant decrease in fitness due to Muller's ratchet in 20 lineages of the RNA bacteriophage Φ6. These results show that deleterious mutations are generated at a sufficiently high rate to advance Muller's ratchet in an RNA virus and that beneficial, backward and compensatory mutations cannot stop the ratchet in the observed range of fitness decrease.

Maintaining evolvability.

PubMed

Crow, James F

2008-12-01

Although molecular methods, such as QTL mapping, have revealed a number of loci with large effects, it is still likely that the bulk of quantitative variability is due to multiple factors, each with small effect. Typically, these have a large additive component. Conventional wisdom argues that selection, natural or artificial, uses up additive variance and thus depletes its supply. Over time, the variance should be reduced, and at equilibrium be near zero. This is especially expected for fitness and traits highly correlated with it. Yet, populations typically have a great deal of additive variance, and do not seem to run out of genetic variability even after many generations of directional selection. Long-term selection experiments show that populations continue to retain seemingly undiminished additive variance despite large changes in the mean value. I propose that there are several reasons for this. (i) The environment is continually changing so that what was formerly most fit no longer is. (ii) There is an input of genetic variance from mutation, and sometimes from migration. (iii) As intermediate-frequency alleles increase in frequency towards one, producing less variance (as p --> 1, p(1 - p) --> 0), others that were originally near zero become more common and increase the variance. Thus, a roughly constant variance is maintained. (iv) There is always selection for fitness and for characters closely related to it. To the extent that the trait is heritable, later generations inherit a disproportionate number of genes acting additively on the trait, thus increasing genetic variance. For these reasons a selected population retains its ability to evolve. Of course, genes with large effect are also important. Conspicuous examples are the small number of loci that changed teosinte to maize, and major phylogenetic changes in the animal kingdom. The relative importance of these along with duplications, chromosome rearrangements, horizontal transmission and polyploidy is yet to be determined. It is likely that only a case-by-case analysis will provide the answers. Despite the difficulties that complex interactions cause for evolution in Mendelian populations, such populations nevertheless evolve very well. Longlasting species must have evolved mechanisms for coping with such problems. Since such difficulties do not arise in asexual populations, a comparison of epistatic patterns in closely related sexual and asexual species might provide some important insights.

The solution structure of omega-Aga-IVB, a P-type calcium channel antagonist from venom of the funnel web spider, Agelenopsis aperta.

PubMed

Reily, M D; Thanabal, V; Adams, M E

1995-02-01

The 48 amino acid peptides omega-Aga-IVA and omega-Aga-IVB are the first agents known to specifically block P-type calcium channels in mammalian brain, thus complementing the existing suite of pharmacological tools used for characterizing calcium channels. These peptides provide a new set of probes for studies aimed at elucidating the structural basis underlying the subtype specificity of calcium channel antagonists. We used 288 NMR-derived constraints in a protocol combining distance geometry and molecular dynamics employing the program DGII, followed by energy minimization with Discover to derive the three-dimensional structure of omega-Aga-IVB. The toxin consists of a well-defined core region, comprising seven solvent-shielded residues and a well-defined triple-stranded beta-sheet. Four loop regions have average backbone rms deviations between 0.38 and 1.31 A, two of which are well-defined type-II beta-turns. Other structural features include disordered C- and N-termini and several conserved basic amino acids that are clustered on one face of the molecule. The reported structure suggests a possible surface for interaction with the channel. This surface contains amino acids that are identical to those of another known P-type calcium channel antagonist, omega-Aga-IVA, and is rich in basic residues that may have a role in binding to the anionic sites in the extracellular regions of the calcium channel.

Coordination Chemistry of Diiodine and Implications for the Oxidation Capacity of the Synergistic Ag(+) /X2 (X=Cl, Br, I) System.

PubMed

Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

2016-08-01

The synergistic Ag(+) /X2 system (X=Cl, Br, I) is a very strong, but ill-defined oxidant-more powerful than X2 or Ag(+) alone. Intermediates for its action may include [Agm (X2 )n ](m+) complexes. Here, we report on an unexpectedly variable coordination chemistry of diiodine towards this direction: (A)Ag-I2 -Ag(A), [Ag2 (I2 )4 ](2+) (A(-) )2 and [Ag2 (I2 )6 ](2+) (A(-) )2 ⋅(I2 )x≈0.65 form by reaction of Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) with diiodine (single crystal/powder XRD, Raman spectra and quantum-mechanical calculations). The molecular (A)Ag-I2 -Ag(A) is ideally set up to act as a 2 e(-) oxidant with stoichiometric formation of 2 AgI and 2 A(-) . Preliminary reactivity tests proved this (A)Ag-I2 -Ag(A) starting material to oxidize n-C5 H12 , C3 H8 , CH2 Cl2 , P4 or S8 at room temperature. A rough estimate of its electron affinity places it amongst very strong oxidizers like MF6 (M=4d metals). This suggests that (A)Ag-I2 -Ag(A) will serve as an easily in bulk accessible, well-defined, and very potent oxidant with multiple applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Concerted evolution of life stage performances signals recent selection on yeast nitrogen use.

PubMed

Ibstedt, Sebastian; Stenberg, Simon; Bagés, Sara; Gjuvsland, Arne B; Salinas, Francisco; Kourtchenko, Olga; Samy, Jeevan K A; Blomberg, Anders; Omholt, Stig W; Liti, Gianni; Beltran, Gemma; Warringer, Jonas

2015-01-01

Exposing natural selection driving phenotypic and genotypic adaptive differentiation is an extraordinary challenge. Given that an organism's life stages are exposed to the same environmental variations, we reasoned that fitness components, such as the lag, rate, and efficiency of growth, directly reflecting performance in these life stages, should often be selected in concert. We therefore conjectured that correlations between fitness components over natural isolates, in a particular environmental context, would constitute a robust signal of recent selection. Critically, this test for selection requires fitness components to be determined by different genetic loci. To explore our conjecture, we exhaustively evaluated the lag, rate, and efficiency of asexual population growth of natural isolates of the model yeast Saccharomyces cerevisiae in a large variety of nitrogen-limited environments. Overall, fitness components were well correlated under nitrogen restriction. Yeast isolates were further crossed in all pairwise combinations and coinheritance of each fitness component and genetic markers were traced. Trait variations tended to map to quantitative trait loci (QTL) that were private to a single fitness component. We further traced QTLs down to single-nucleotide resolution and uncovered loss-of-function mutations in RIM15, PUT4, DAL1, and DAL4 as the genetic basis for nitrogen source use variations. Effects of SNPs were unique for a single fitness component, strongly arguing against pleiotropy between lag, rate, and efficiency of reproduction under nitrogen restriction. The strong correlations between life stage performances that cannot be explained by pleiotropy compellingly support adaptive differentiation of yeast nitrogen source use and suggest a generic approach for detecting selection. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Three new combinations in Drepanopeziza for species on poplar

USDA-ARS?s Scientific Manuscript database

Three species of Drepanopeziza that cause diseases of poplars have been known using scientific names for their sexual and asexual morphs, which is no longer allowed with the change to one scientific name for fungi. For each species, the oldest epithet is provided by the asexual morph; however, neith...

Temporal and Spatial Regulation of Gene Expression during Asexual Development of Neurospora crassa

USDA-ARS?s Scientific Manuscript database

In this study we profiled spatial and temporal transcriptional changes during asexual sporulation in the filamentous fungus Neurospora crassa. Aerial tissue was separated from the mycelium to allow detection of genes specific to each tissue. We identified 2641 genes that were differentially expresse...

Potato (Solanum tuberosum) greenhouse tuber production as an assay for asexual reproduction effects from herbicides

EPA Science Inventory

The present study determined whether young potato plants can be used as an assay to indicate potential effects of pesticides on asexual reproduction. Solanum tuberosum (Russet Burbank) plants were grown from seed pieces in a mineral soil in pots under greenhouse conditions. Plant...

American Gastroenterological Association guidelines are inaccurate in detecting pancreatic cysts with advanced neoplasia: a clinicopathologic study of 225 patients with supporting molecular data.

PubMed

Singhi, Aatur D; Zeh, Herbert J; Brand, Randall E; Nikiforova, Marina N; Chennat, Jennifer S; Fasanella, Kenneth E; Khalid, Asif; Papachristou, Georgios I; Slivka, Adam; Hogg, Melissa; Lee, Kenneth K; Tsung, Allan; Zureikat, Amer H; McGrath, Kevin

2016-06-01

The American Gastroenterological Association (AGA) recently reported evidence-based guidelines for the management of asymptomatic neoplastic pancreatic cysts. These guidelines advocate a higher threshold for surgical resection than prior guidelines and imaging surveillance for a considerable number of patients with pancreatic cysts. The aims of this study were to assess the accuracy of the AGA guidelines in detecting advanced neoplasia and present an alternative approach to pancreatic cysts. The study population consisted of 225 patients who underwent EUS-guided FNA for pancreatic cysts between January 2014 and May 2015. For each patient, clinical findings, EUS features, cytopathology results, carcinoembryonic antigen analysis, and molecular testing of pancreatic cyst fluid were reviewed. Molecular testing included the assessment of hotspot mutations and deletions for KRAS, GNAS, VHL, TP53, PIK3CA, and PTEN. Diagnostic pathology results were available for 41 patients (18%), with 13 (6%) harboring advanced neoplasia. Among these cases, the AGA guidelines identified advanced neoplasia with 62% sensitivity, 79% specificity, 57% positive predictive value, and 82% negative predictive value. Moreover, the AGA guidelines missed 45% of intraductal papillary mucinous neoplasms with adenocarcinoma or high-grade dysplasia. For cases without confirmatory pathology, 27 of 184 patients (15%) with serous cystadenomas (SCAs) based on EUS findings and/or VHL alterations would continue magnetic resonance imaging (MRI) surveillance. In comparison, a novel algorithmic pathway using molecular testing of pancreatic cyst fluid detected advanced neoplasias with 100% sensitivity, 90% specificity, 79% positive predictive value, and 100% negative predictive value. The AGA guidelines were inaccurate in detecting pancreatic cysts with advanced neoplasia. Furthermore, because the AGA guidelines manage all neoplastic cysts similarly, patients with SCAs will continue to undergo unnecessary MRI surveillance. The results of an alternative approach with integrative molecular testing are encouraging but require further validation. Copyright © 2016 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

A Comparison of the Hormonal Profile of Early Androgenetic Alopecia in Men With the Phenotypic Equivalent of Polycystic Ovarian Syndrome in Women.

PubMed

Sanke, Sarita; Chander, Ram; Jain, Anju; Garg, Taru; Yadav, Pravesh

2016-09-01

Early androgenetic alopecia (AGA) is patterned hair loss occurring before age 30 years. Early AGA in men is frequently reported as the phenotypic equivalent of polycystic ovarian syndrome (PCOS) in women, which carries the risk of developing obesity, metabolic syndrome, and cardiovascular diseases. Very few studies have been conducted to evaluate this. To study the hormonal profile of men with early AGA and to evaluate if early AGA in men can be considered as the phenotypic equivalent of PCOS, the associated risks of which are well known. This case-control study was conducted from January 1, 2014, to March 31, 2015, in a tertiary care government hospital. Fifty-seven men aged 19 to 30 years presenting with patterned hair loss were recruited as study participants. Thirty-two age-matched men with no evidence of hair loss were recruited as controls. Men who had any established endocrine disorder, diabetes mellitus, or cardiovascular disease and those who took any oral medication or hormonal treatment for hair loss were excluded from the study. The serum concentrations of total testosterone, sex hormone-binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, fasting plasma glucose, and insulin levels were measured. Insulin resistance (IR) and free androgen index (FAI) were calculated and compared with age- and sex-matched controls. The primary outcome was to measure the clinico-endocrinological profiles (LH, FSH, SHBG, DHEAS, and testosterone levels) of men with early AGA and to compare it with the PCOS profile; the secondary outcome was to establish a relationship between this endocrinological profile and IR. Compared with the 32 controls, the 57 participants with AGA showed significantly increased mean (SD) levels of testosterone (24.61 [7.97] vs 20.57 [4.9] nmol/L; P = .04), DHEAS (3.63 [2.19] vs 2.64 [1.49] µg/mL; P = .02), LH (7.78 [3.19] vs 4.56 [2.01] mIU/mL; P < .001), and prolactin (14.14 [9.48] vs 9.97 [3.12] ng/mL; P = .01) and decreased mean levels of FSH (4.02 [2.69] vs 5.66 [1.93] mIU/mL; P < .001) and SHBG (35.07 [11.11] vs 46.41 [14.03] nmol/L; P < .001). The mean FAI and LH/FSH ratio were was also increased in the AGA group. These hormonal parameters resemble the well-known profile of women with PCOS. The mean (SD) insulin levels did not show any significant difference between the cases and controls (6.34 [3.92] vs 5.09 [3.38] μIU/mL; P = .07). There was no statistically significant association between hormone levels and AGA or IR grade severity. Men with early AGA could be considered as male phenotypic equivalents of women with PCOS. They can be at risk of developing the same complications associated with PCOS, including obesity, metabolic syndrome, IR, cardiovascular diseases, and infertility.

Life in the Cosmic Context. An Astrobiology Course as an Experiment in Transdisciplinarity

NASA Astrophysics Data System (ADS)

Friaça, A. C. S.; Janot Pacheco, E.

2014-10-01

``Life in the Cosmic Context" (AGA0316) is the astrobiology course offered by University of São Paulo to undergraduate students of science and humanities majors. The variety of background of the population attending AGA0316 and the broad scope of the addresssed issues makes this course a laboratory of transdisciplinarity.

Transmitter release and presynaptic Ca2+ currents blocked by the spider toxin omega-Aga-IVA.

PubMed

Protti, D A; Uchitel, O D

1993-12-13

Mammalian neuromuscular transmission is resistant to L and N type calcium channel blockers but very sensitive to a low molecular weight funnel web spider venom toxin, FTX, which selectively blocks P type calcium channels. To further characterize the calcium channels involved in neuromuscular transmission we studied the effect of omega Agatoxin (omega-Aga-IVA) a polypeptide P type channel blocker from the same spider venom. We show that omega-Aga-IVA is a potent and irreversible inhibitor of the presynaptic Ca2+ currents and of acetylcholine release induced by electrical stimulation or by K+ depolarization. This provides further evidences that transmitter release at the mammalian neuromuscular junction is mediated by P type Ca2+ channels.

MULTI-COMPONENT ANALYSIS OF POSITION-VELOCITY CUBES OF THE HH 34 JET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez-Gonzalez, A.; Esquivel, A.; Raga, A. C.

We present an analysis of H{alpha} spectra of the HH 34 jet with two-dimensional spectral resolution. We carry out multi-Gaussian fits to the spatially resolved line profiles and derive maps of the intensity, radial velocity, and velocity width of each of the components. We find that close to the outflow source we have three components: a high (negative) radial velocity component with a well-collimated, jet-like morphology; an intermediate velocity component with a broader morphology; and a positive radial velocity component with a non-collimated morphology and large linewidth. We suggest that this positive velocity component is associated with jet emission scatteredmore » in stationary dust present in the circumstellar environment. Farther away from the outflow source, we find only two components (a high, negative radial velocity component, which has a narrower spatial distribution than an intermediate velocity component). The fitting procedure was carried out with the new AGA-V1 code, which is available online and is described in detail in this paper.« less

Internal brooding favours pre-metamorphic chimerism in a non-colonial cnidarian, the sea anemone Urticina felina

PubMed Central

Mercier, Annie; Sun, Zhao; Hamel, Jean-François

2011-01-01

The concept of intraorganismal genetic heterogeneity resulting from allogeneic fusion (i.e. chimerism) has almost exclusively been explored in modular organisms that have the capacity to reproduce asexually, such as colonial ascidians and corals. Apart from medical conditions in mammals, the natural development of chimeras across ontogenetic stages has not been investigated in any unitary organism incapable of asexual propagation. Furthermore, chimerism was mainly studied among gregarious settlers to show that clustering of genetically similar individuals upon settlement promotes the occurrence of multi-chimeras exhibiting greater fitness. The possible occurrence of chimeric embryos and larvae prior to settlement has not received any attention. Here we document for the first time the presence of natural chimeras in brooded embryos and larvae of a unitary cnidarian, the sea anemone Urticina felina. Rates of visible bi- and multi-chimerism of up to 3.13 per cent were measured in the broods of 16 females. Apart from these sectorial chimeras, monitored fusion events also yielded homogeneous chimeric entities (mega-larvae) suggesting that the actual rates of natural chimerism in U. felina are greater than predicted by visual assessment. In support of this assumption, the broods of certain individuals comprised a dominant proportion (to 90%) of inexplicably large embryos and larvae (relative to oocyte size). Findings of fusion and chimerism in a unitary organism add a novel dimension to the framework within which the mechanisms and evolutionary significance of genetic heterogeneity in animal taxa can be explored. PMID:21508035

A simple culture method inducing sexual reproduction by Fusarium graminearum, the primary causal agent of Fusarium head blight

USDA-ARS?s Scientific Manuscript database

The homothallic ascomycete fungus Fusarium graminearum is the primary causal agent of Fusarium head blight (FHB), a devastating disease of wheat and barley worldwide. The fungus undergoes both asexual and sexual stages in its life cycle. The asexual stage produces conidiospores, whereas the sexual s...

75 FR 3711 - Listing Endangered and Threatened Wildlife and Designating Critical Habitat; 12-month...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-22

... recruitment, and successful reattachment and recruitment of asexual fragments in water depths shallower than 30 meters in four areas in Florida, Puerto Rico, and the U.S. Virgin Islands. The petition seeks to... settlement and recruitment, and the reattachment and recruitment of asexual fragments in water depths...

Plant Growth-Promoting Rhizobacteria Stimulate Vegetative Growth and Asexual Reproduction of Kalanchoe daigremontiana.

PubMed

Park, Yong-Soon; Park, Kyungseok; Kloepper, Joseph W; Ryu, Choong-Min

2015-09-01

Certain bacterial species associate with plant roots in soil. The plant growth-promoting rhizobacteria (PGPR) stimulate plant growth and yield in greenhouse and field. Here, we examined whether application of known bacilli PGPR strains stimulated growth and asexual reproduction in the succulent plant Kalanchoe daigremontiana. Four PGPR strains B. amyloliquefaciens IN937a, B. cereus BS107, B. pumilus INR7, and B. subtilis GB03 were applied to young plantlets by soil-drenching, and plant growth and development was monitored for three months. Aerial growth was significantly stimulated in PGPR-inoculated plants, which was observed as increases in plant height, shoot weight, and stem width. The stimulated growth influenced plant development by increasing the total number of leaves per plant. Treatment with bacilli also increased the total root biomass compared with that of control plants, and led to a 2-fold increase in asexual reproduction and plantlet formation on the leaf. Collectively, our results firstly demonstrate that Bacillus spp. promote vegetative development of K. daigremontiana, and the enhanced growth stimulates asexual reproduction and plantlet formation.

Ontology for the asexual development and anatomy of the colonial chordate Botryllus schlosseri.

PubMed

Manni, Lucia; Gasparini, Fabio; Hotta, Kohji; Ishizuka, Katherine J; Ricci, Lorenzo; Tiozzo, Stefano; Voskoboynik, Ayelet; Dauga, Delphine

2014-01-01

Ontologies provide an important resource to integrate information. For developmental biology and comparative anatomy studies, ontologies of a species are used to formalize and annotate data that are related to anatomical structures, their lineage and timing of development. Here, we have constructed the first ontology for anatomy and asexual development (blastogenesis) of a bilaterian, the colonial tunicate Botryllus schlosseri. Tunicates, like Botryllus schlosseri, are non-vertebrates and the only chordate taxon species that reproduce both sexually and asexually. Their tadpole larval stage possesses structures characteristic of all chordates, i.e. a notochord, a dorsal neural tube, and gill slits. Larvae settle and metamorphose into individuals that are either solitary or colonial. The latter reproduce both sexually and asexually and these two reproductive modes lead to essentially the same adult body plan. The Botryllus schlosseri Ontology of Development and Anatomy (BODA) will facilitate the comparison between both types of development. BODA uses the rules defined by the Open Biomedical Ontologies Foundry. It is based on studies that investigate the anatomy, blastogenesis and regeneration of this organism. BODA features allow the users to easily search and identify anatomical structures in the colony, to define the developmental stage, and to follow the morphogenetic events of a tissue and/or organ of interest throughout asexual development. We invite the scientific community to use this resource as a reference for the anatomy and developmental ontology of B. schlosseri and encourage recommendations for updates and improvements.

Transcriptional Changes in the Transition from Vegetative Cells to Asexual Development in the Model Fungus Aspergillus nidulans

PubMed Central

Garzia, Aitor; Etxebeste, Oier; Rodríguez-Romero, Julio; Fischer, Reinhard; Espeso, Eduardo A.

2013-01-01

Morphogenesis encompasses programmed changes in gene expression that lead to the development of specialized cell types. In the model fungus Aspergillus nidulans, asexual development involves the formation of characteristic cell types, collectively known as the conidiophore. With the aim of determining the transcriptional changes that occur upon induction of asexual development, we have applied massive mRNA sequencing to compare the expression pattern of 19-h-old submerged vegetative cells (hyphae) with that of similar hyphae after exposure to the air for 5 h. We found that the expression of 2,222 (20.3%) of the predicted 10,943 A. nidulans transcripts was significantly modified after air exposure, 2,035 being downregulated and 187 upregulated. The activation during this transition of genes that belong specifically to the asexual developmental pathway was confirmed. Another remarkable quantitative change occurred in the expression of genes involved in carbon or nitrogen primary metabolism. Genes participating in polar growth or sexual development were transcriptionally repressed, as were those belonging to the HogA/SakA stress response mitogen-activated protein (MAP) kinase pathway. We also identified significant expression changes in several genes purportedly involved in redox balance, transmembrane transport, secondary metabolite production, or transcriptional regulation, mainly binuclear-zinc cluster transcription factors. Genes coding for these four activities were usually grouped in metabolic clusters, which may bring regulatory implications for the induction of asexual development. These results provide a blueprint for further stage-specific gene expression studies during conidiophore development. PMID:23264642

Is meiosis a fundamental cause of inviability among sexual and asexual plants and animals?

PubMed

Levitis, Daniel A; Zimmerman, Kolea; Pringle, Anne

2017-08-16

Differences in viability between asexually and sexually generated offspring strongly influence the selective advantage and therefore the prevalence of sexual reproduction (sex). However, no general principle predicts when sexual offspring will be more viable than asexual offspring. We hypothesize that when any kind of reproduction is based on a more complex cellular process, it will encompass more potential failure points, and therefore lower offspring viability. Asexual reproduction (asex) can be simpler than sex, when offspring are generated using only mitosis. However, when asex includes meiosis and meiotic restitution, gamete production is more complex than in sex. We test our hypothesis by comparing the viability of asexual and closely related sexual offspring across a wide range of plants and animals, and demonstrate that meiotic asex does result in lower viability than sex; without meiosis, asex is mechanistically simple and provides higher viability than sex. This phylogenetically robust pattern is supported in 42 of 44 comparisons drawn from diverse plants and animals, and is not explained by the other variables included in our model. Other mechanisms may impact viability, such as effects of reproductive mode on heterozygosity and subsequent viability, but we propose the complexity of cellular processes of reproduction, particularly meiosis, as a fundamental cause of early developmental failure and mortality. Meiosis, the leading cause of inviability in humans, emerges as a likely explanation of offspring inviability among diverse eukaryotes. © 2017 The Author(s).

Geographic parthenogenesis and plant-enemy interactions in the common dandelion.

PubMed

Verhoeven, Koen J F; Biere, Arjen

2013-01-28

Many species with sexual and asexual variants show a pattern of geographic parthenogenesis where asexuals have broader and higher-latitude distribution than sexuals. Because sexual reproduction is often considered a costly evolutionary strategy that is advantageous in the face of selection by coevolving pests and pathogens, one possible explanation for geographic parthenogenesis is that populations at higher latitudes are exposed to fewer pests and pathogens. We tested this hypothesis in the common dandelion (Taraxacum officinale), a species with well-established geographic parthenogenesis, by screening prevalence and effects of several specialized pests and pathogens in natural dandelion populations. We did a population survey of 18 dandelion populations along a geographic transect that ranged from the area where sexual and asexual dandelions co-occur northward into the area where only asexuals occur. In addition we used four southern and four northern populations in a 8x8 cross-inoculation greenhouse experiment in which plants were exposed experimentally to each other's natural field soil microbial communities. The cross-inoculation experiment indicated a higher pathogenicity of soil microbial communities from the southern, mostly sexual, populations compared to soil microbial communities from the northern asexual populations. Northern dandelion populations also showed reduced infestation by a specialized seed-eating weevil. A similar trend of reduced rust fungus infection in northern populations was observed but this trend was not statistically significant. The prevalence of pests and pathogens decreased along the south-to-north axis of geographic parthenogenesis. This highlights the potential of biotic interactions in shaping patterns of geographic parthenogenesis.

Ontology for the Asexual Development and Anatomy of the Colonial Chordate Botryllus schlosseri

PubMed Central

Manni, Lucia; Gasparini, Fabio; Hotta, Kohji; Ishizuka, Katherine J.; Ricci, Lorenzo; Tiozzo, Stefano; Voskoboynik, Ayelet; Dauga, Delphine

2014-01-01

Ontologies provide an important resource to integrate information. For developmental biology and comparative anatomy studies, ontologies of a species are used to formalize and annotate data that are related to anatomical structures, their lineage and timing of development. Here, we have constructed the first ontology for anatomy and asexual development (blastogenesis) of a bilaterian, the colonial tunicate Botryllus schlosseri. Tunicates, like Botryllus schlosseri, are non-vertebrates and the only chordate taxon species that reproduce both sexually and asexually. Their tadpole larval stage possesses structures characteristic of all chordates, i.e. a notochord, a dorsal neural tube, and gill slits. Larvae settle and metamorphose into individuals that are either solitary or colonial. The latter reproduce both sexually and asexually and these two reproductive modes lead to essentially the same adult body plan. The Botryllus schlosseri Ontology of Development and Anatomy (BODA) will facilitate the comparison between both types of development. BODA uses the rules defined by the Open Biomedical Ontologies Foundry. It is based on studies that investigate the anatomy, blastogenesis and regeneration of this organism. BODA features allow the users to easily search and identify anatomical structures in the colony, to define the developmental stage, and to follow the morphogenetic events of a tissue and/or organ of interest throughout asexual development. We invite the scientific community to use this resource as a reference for the anatomy and developmental ontology of B. schlosseri and encourage recommendations for updates and improvements. PMID:24789338

Effects of cold treatments on fitness and mode of reproduction in the diploid and polyploid alpine plant Ranunculus kuepferi (Ranunculaceae).

PubMed

Klatt, Simone; Schinkel, Christoph C F; Kirchheimer, Bernhard; Dullinger, Stefan; Hörandl, Elvira

2018-06-08

Alpine plants grow in harsh environments and are thought to face occasional frost during the sensitive reproductive phase. Apomixis (asexual reproduction via seed) can be advantageous when sexual reproduction is disturbed by cold stress. Apomictic polyploids tend to grow in colder climates than their sexual diploid relatives. Whether cold temperatures actually induce apomixis was unknown to date. We tested experimentally in climate cabinets for effects of low temperatures and repeated frost on phenology, fitness and mode of reproduction in diploid and tetraploid cytotypes of the alpine species Ranunculus kuepferi. The reproduction mode was determined via flow cytometric seed screening (FCSS). Diploids produced the first flowers earlier than the tetraploids in all treatments. Cold treatments significantly reduced the fitness of both cytotypes regarding seed set, and increased the frequency of apomictic seed formation in diploids, but not in tetraploids. Over consecutive years, the degree of facultative apomixis showed individual phenotypic plasticity. Cold stress is correlated to expression of apomixis in warm-adapted, diploid R. kuepferi, while temperature-tolerant tetraploids just maintain facultative apomixis as a possible adaptation to colder climates. However, expression of apomixis may not depend on polyploidy, but rather on failure of the sexual pathway.

Comparative transcriptome analysis of obligately asexual and cyclically sexual rotifers reveals genes with putative functions in sexual reproduction, dormancy, and asexual egg production.

PubMed

Hanson, Sara J; Stelzer, Claus-Peter; Welch, David B Mark; Logsdon, John M

2013-06-19

Sexual reproduction is a widely studied biological process because it is critically important to the genetics, evolution, and ecology of eukaryotes. Despite decades of study on this topic, no comprehensive explanation has been accepted that explains the evolutionary forces underlying its prevalence and persistence in nature. Monogonont rotifers offer a useful system for experimental studies relating to the evolution of sexual reproduction due to their rapid reproductive rate and close relationship to the putatively ancient asexual bdelloid rotifers. However, little is known about the molecular underpinnings of sex in any rotifer species. We generated mRNA-seq libraries for obligate parthenogenetic (OP) and cyclical parthenogenetic (CP) strains of the monogonont rotifer, Brachionus calyciflorus, to identify genes specific to both modes of reproduction. Our differential expression analysis identified receptors with putative roles in signaling pathways responsible for the transition from asexual to sexual reproduction. Differential expression of a specific copy of the duplicated cell cycle regulatory gene CDC20 and specific copies of histone H2A suggest that such duplications may underlie the phenotypic plasticity required for reproductive mode switch in monogononts. We further identified differential expression of genes involved in the formation of resting eggs, a process linked exclusively to sex in this species. Finally, we identified transcripts from the bdelloid rotifer Adineta ricciae that have significant sequence similarity to genes with higher expression in CP strains of B. calyciflorus. Our analysis of global gene expression differences between facultatively sexual and exclusively asexual populations of B. calyciflorus provides insights into the molecular nature of sexual reproduction in rotifers. Furthermore, our results offer insight into the evolution of obligate asexuality in bdelloid rotifers and provide indicators important for the use of monogononts as a model system for investigating the evolution of sexual reproduction.

Topical application of the Wnt/β-catenin activator methyl vanillate increases hair count and hair mass index in women with androgenetic alopecia.

PubMed

Tosti, Antonella; Zaiac, Martin N; Canazza, Agnese; Sanchis-Gomar, Fabian; Pareja-Galeano, Helios; Alis, Rafael; Lucia, Alejandro; Emanuele, Enzo

2016-12-01

Activation of the WNT/β-catenin pathway has emerged as a potential therapeutic target in androgenetic alopecia (AGA). Methyl vanillate (MV) - a safe plant-derived ingredient - has been recently shown to activate the WNT/β-catenin signaling. Objectives Two distinct substudies were conducted. First, we designed a 6-month, uncontrolled, open-label clinical study to investigate whether topically applied MV may increase hair count and hair mass index (HMI) in female AGA. Second, we conducted a molecular study on the effect of MV on WNT10B mRNA expression in scalp biopsies of women with AGA. A total of 20 Caucasian women (age range: 25-57 years) with AGA (Sinclair grade 1-2) were included. The research product was an alcohol-free formulation supplied in the form of a spray containing 0.2% MV as the active ingredient. In the clinical study, hair count and HMI were found to increase at 6 months by 6% (P < 0.01) and 12% (P < 0.001), respectively, compared with baseline. No participant discontinued treatment due to adverse effects, and the overall patient satisfaction was good. At the molecular level, the topical application of the research product resulted in a 32% increase in WNT10B mRNA expression levels in the temporal scalp area (P < 0.001). Our pilot data suggest that topical MV can increase hair count and HMI by inducing WNT10B expression in the scalp, potentially serving as a novel treatment strategy for female AGA. © 2016 Wiley Periodicals, Inc.

Identification of a new plant extract for androgenic alopecia treatment using a non-radioactive human hair dermal papilla cell-based assay.

PubMed

Jain, Ruchy; Monthakantirat, Orawan; Tengamnuay, Parkpoom; De-Eknamkul, Wanchai

2016-01-21

Androgenic alopecia (AGA) is a major type of human scalp hair loss, which is caused by two androgens: testosterone (T) and 5α-dihydrotestosterone (5α-DHT). Both androgens bind to the androgen receptor (AR) and induce androgen-sensitive genes within the human hair dermal papilla cells (HHDPCs), but 5α-DHT exhibits much higher binding affinity and potency than T does in inducing the involved androgen-sensitive genes. Changes in the induction of androgen-sensitive genes during AGA are caused by the over-production of 5α-DHT by the 5α-reductase (5α-R) enzyme; therefore, one possible method to treat AGA is to inhibit this enzymatic reaction. RT-PCR was used to identify the presence of the 5α-R and AR within HHDPCs. A newly developed AGA-relevant HHDPC-based assay combined with non-radioactive thin layer chromatography (TLC) detection was used for screening crude plant extracts for the identification of new 5α-R inhibitors. HHDPCs expressed both 5α-R type 1 isoform of the enzyme (5α-R1) and AR in all of the passages used in this study. Among the thirty tested extracts, Avicennia marina (AM) displayed the highest inhibitory activity at the final concentration of 10 μg/ml, as the production of 5α-DHT decreased by 52% (IC50 = 9.21 ± 0.38 μg/ml). Avicennia marina (AM) was identified as a potential candidate for the treatment of AGA based on its 5α-R1-inhibitory activity.

[Obstetric prognostic factors of newborn infants with very low birth weight (< or = 1,500 gram) with reference to survival rate and early childhood development].

PubMed

Hamm, W; Göhring, U J; Günther, M; Kribs, A; Neuhaus, W; Roth, B; Bolte, A

1995-03-01

Prognostic factors influencing survival in 235 very low birthweight prematures (< or = 1500 g) born between 1986 and 15.11. 1993 at the Department of Obstetrics and Gynaecology, University Hospital of Cologne, were retrospectively evaluated. Chromosomal anomalies and severe congenital malformations were excluded. Of 180 singletons 84 were classified as appropriate-for-gestational-age (AGA) and 96 as small-for-gestational-age (SGA). By interrogating the attending paediatricians data regarding the early development of 62/65 surviving singletons born between 1986 to 1990 were recorded (follow-up rate 95%). Survival was significantly correlated to singleton pregnancy (p < 0.05), female sex (p = 0.001) and in the AGA-prematures to prenatal corticoid prophylaxis. With similar mean birthweight SGA-singletons showed a three weeks higher mean gestational age; the mortality showed an inverse correlation to birthweight and gestational age being 11% higher in the AGA-group compared with the SGA-group (32% versus 21%). At the age of between 11 months and 6 years severe handicaps and developmental retardations were found more often in previous AGA-prematures (6/26) than in previous SGA-prematures (4/36); type and degree of later handicap were not correlated to birthweight. According to our results survival rates of very low birthweight prematures are strongly influenced by singleton pregnancy, by fetal sex, by gestational age and in the AGA-group by prenatal corticoid prophylaxis; mortality shows an inverted correlation to birthweight and gestational age, whereas the later prognosis of survivors does not seem to be influenced by birthweight or gestational age.

Efficacy of a cosmetic phyto-caffeine shampoo in female androgenetic alopecia.

PubMed

Bussoletti, Carolina; Tolaini, Maria V; Celleno, Leonardo

2018-03-06

Androgenetic alopecia (AGA) is the most common type of hair loss in both males as well as females, occurring in up to 57% of women by the age of 80 years. Androgenetic alopecia is associated with a high psychological burden and often results in substantially reduced quality of life, poor body image and low self-esteem, particularly in women. Caffeine-based products have shown promise, both in vitro and in vivo, as potential treatments for AGA. This study was performed to determine the efficacy of a phyto-caffeine- containing shampoo used over a 6-month period in female subjects with AGA. This was a single-centre, double-blind parallel trial in which female subjects with AGA were randomized to either a phyto-caffeine-containing shampoo or a control shampoo. The primary endpoint was the change from baseline in the number of hairs pulled in a hair pull test at 6 months. Hair loss intensity, hair strength, subject satisfaction and tolerability were also assessed. Subjects using the phyto-caffeine-containing shampoo had significantly fewer hairs pulled in a hair pull test at 6 months, compared with subjects using the control shampoo (-3.1 vs -0.5 hairs; p<0.001). The majority of pre-specified secondary endpoints were also significantly improved for subjects using the phyto-caffeine- containing shampoo, compared with controls. Both products were very well tolerated. Compared with a control shampoo, a phyto-caffeine-containing shampoo was more efficacious, with respect to the number of hairs being pulled out at 6 months, hair loss intensity and hair strength in subjects with AGA.

Use of an alpha-galactosidase gene as a food-grade selection marker for Streptococcus thermophilus.

PubMed

Labrie, S; Bart, C; Vadeboncoeur, C; Moineau, S

2005-07-01

The alpha-galactosidase gene (aga) of Lactococcus raffinolactis ATCC 43920 was previously shown to be an efficient food-grade selection marker in Lactococcus lactis and Pediococcus acidilactici but not in Streptococcus thermophilus. In this study, we demonstrated that the alpha-galactosidase of L. raffinolactis is thermolabile and inoperative at 42 degrees C, the optimal growth temperature of S. thermophilus. An in vitro assay indicated that the activity of this alpha-galactosidase at 42 degrees C was only 3% of that at 30 degrees C, whereas the enzyme retained 23% of its activity at 37 degrees C. Transformation of Strep. thermophilus RD733 with the shuttle-vector pNZ123 bearing the aga gene of L. raffinolactis (pRAF301) generated transformants that were stable and able to grow on melibiose and raffinose at 37 degrees C or below. The transformed cells possessed 6-fold more alpha-galactosidase activity after growth on melibiose than cells grown on lactose. Slot-blot analyses of aga mRNA indicated that repression by lactose occurred at the transcriptional level. The presence of pRAF301 did not interfere with the lactic acid production when the transformed cells of Strep. thermophilus were grown at the optimal temperature in milk. Using the recombinant plasmid pRAF301, which carries a chloramphenicol resistance gene in addition to aga, we showed that both markers were equally efficient at differentiating transformed from nontransformed cells. The aga gene of L. raffinolactis can be used as a highly efficient selection marker in Strep. thermophilus.

Evaluation of Commercially Available Open Circuit Scuba Regulators

DTIC Science & Technology

1987-08-01

ANNEX B LIST OF MANUFACTURERS 1. AGA/IISIERSPIRO U.S. Distributor Intersiro AB AGA/INTERSPIRO S-181 81 Lidingo Sweden Pistol Shop Road Rockfall ...RWV--*-- 40.0 RWV DACOR PACER XLE360 --G- 2.5 OW 600 80 1000 psig Supply Pressure -=70 -- 500 6050 7040 . GI "C - 300 , 𔄃° 4O- 30 200 0100 1030 0 0 0

Use of low-level laser therapy as monotherapy or concomitant therapy for male and female androgenetic alopecia.

PubMed

Munck, Andréia; Gavazzoni, Maria Fernanda; Trüeb, Ralph M

2014-04-01

Androgenetic alopecia (AGA) is the most common form of hair loss in men and in women. Currently, minoxidil and finasteride are the treatments with the highest levels of medical evidence, but patients who exhibit intolerance or poor response to these treatments are in need of additional treatment modalities. The aim was to evaluate the efficacy and safety of low-level laser therapy (LLLT) for AGA, either as monotherapy or as concomitant therapy with minoxidil or finasteride, in an office-based setting. Retrospective observational study of male and female patients with AGA, treated with the 655 nm-HairMax Laser Comb(®), in an office-based setting. Efficacy was assessed with global photographic imaging. Of 32 patients (21 female, 11 male), 8 showed significant, 20 moderate, and 4 no improvement. Improvement was seen both with monotherapy and with concomitant therapy. Improvement was observed as early as 3 months and was sustained up to a maximum observation time of 24 months. No adverse reactions were reported. LLLT represents a potentially effective treatment for both male and female AGA, either as monotherapy or concomitant therapy. Combination treatments with minoxidil, finasteride, and LLLT may act synergistic to enhance hair growth.

Reduced genetic influence on childhood obesity in small for gestational age children

PubMed Central

2013-01-01

Background Children born small-for-gestational-age (SGA) are at increased risk of developing obesity and metabolic diseases later in life, a risk which is magnified if followed by accelerated postnatal growth. We investigated whether common gene variants associated with adult obesity were associated with increased postnatal growth, as measured by BMI z-score, in children born SGA and appropriate for gestational age (AGA) in the Auckland Birthweight Collaborative. Methods A total of 37 candidate SNPs were genotyped on 547 European children (228 SGA and 319 AGA). Repeated measures of BMI (z-score) were used for assessing obesity status, and results were corrected for multiple testing using the false discovery rate. Results SGA children had a lower BMI z-score than non-SGA children at assessment age 3.5, 7 and 11 years. We confirmed 27 variants within 14 obesity risk genes to be individually associated with increasing early childhood BMI, predominantly in those born AGA. Conclusions Genetic risk variants are less important in influencing early childhood BMI in those born SGA than in those born AGA, suggesting that non-genetic or environmental factors may be more important in influencing childhood BMI in those born SGA. PMID:23339409

Characterization of a Glycoside Hydrolase Family 27 α-Galactosidase from Pontibacter Reveals Its Novel Salt-Protease Tolerance and Transglycosylation Activity.

PubMed

Zhou, Junpei; Liu, Yu; Lu, Qian; Zhang, Rui; Wu, Qian; Li, Chunyan; Li, Junjun; Tang, Xianghua; Xu, Bo; Ding, Junmei; Han, Nanyu; Huang, Zunxi

2016-03-23

α-Galactosidases are of great interest in various applications. A glycoside hydrolase family 27 α-galactosidase was cloned from Pontibacter sp. harbored in a saline soil and expressed in Escherichia coli. The purified recombinant enzyme (rAgaAHJ8) was little or not affected by 3.5-30.0% (w/v) NaCl, 10.0-100.0 mM Pb(CH3COO)2, 10.0-60.0 mM ZnSO4, or 8.3-100.0 mg mL(-1) trypsin and by most metal ions and chemical reagents at 1.0 and 10.0 mM concentrations. The degree of synergy on enzymatic degradation of locust bean gum and guar gum by an endomannanase and rAgaAHJ8 was 1.22-1.54. In the presence of trypsin, the amount of reducing sugars released from soybean milk treated by rAgaAHJ8 was approximately 3.8-fold compared with that treated by a commercial α-galactosidase. rAgaAHJ8 showed transglycosylation activity when using sucrose, raffinose, and 3-methyl-1-butanol as the acceptors. Furthermore, potential factors for salt adaptation of the enzyme were presumed.

Competing sexual and asexual generic names in Pucciniomycotina and Ustilaginomycotina (Basidiomycota) and recommendations for use

USDA-ARS?s Scientific Manuscript database

With the change to one scientific name for fungi, generic names representing sexual and asexual morphs have been evaluated to determine which name to use when two names represent the same genus and thus compete for use. In this paper generic names of the Pucciniomycotina and Ustilaginomycotina are e...

Cryptic Fitness Advantage: Diploids Invade Haploid Populations Despite Lacking Any Apparent Advantage as Measured by Standard Fitness Assays

PubMed Central

Gerstein, Aleeza C.; Otto, Sarah P.

2011-01-01

Ploidy varies tremendously within and between species, yet the factors that influence when or why ploidy variants are adaptive remains poorly understood. Our previous work found that diploid individuals repeatedly arose within ten replicate haploid populations of Saccharomyces cerevisiae, and in each case we witnessed diploid takeover within 1800 asexual generations of batch culture evolution in the lab. The character that allowed diploids to rise in frequency within haploid populations remains unknown. Here we present a number of experiments conducted with the goal to determine what this trait (or traits) might have been. Experiments were conducted both by sampling a small number of colonies from the stocks frozen every two weeks (93 generations) during the original experiment, as well through sampling a larger number of colonies at the two time points where polymorphism for ploidy was most prevalent. Surprisingly, none of our fitness component measures (lag phase, growth rate, biomass production) indicated an advantage to diploidy. Similarly, competition assays against a common competitor and direct competition between haploid and diploid colonies isolated from the same time point failed to indicate a diploid advantage. Furthermore, we uncovered a tremendous amount of trait variation among colonies of the same ploidy level. Only late-appearing diploids showed a competitive advantage over haploids, indicating that the fitness advantage that allowed eventual takeover was not diploidy per se but an attribute of a subset of diploid lineages. Nevertheless, the initial rise in diploids to intermediate frequency cannot be explained by any of the fitness measures used; we suggest that the resolution to this mystery is negative frequency-dependent selection, which is ignored in the standard fitness measures used. PMID:22174734

Non-adaptive and adaptive hybrid approaches for enhancing water quality management

NASA Astrophysics Data System (ADS)

Kalwij, Ineke M.; Peralta, Richard C.

2008-09-01

SummaryUsing optimization to help solve groundwater management problems cost-effectively is becoming increasingly important. Hybrid optimization approaches, that combine two or more optimization algorithms, will become valuable and common tools for addressing complex nonlinear hydrologic problems. Hybrid heuristic optimizers have capabilities far beyond those of a simple genetic algorithm (SGA), and are continuously improving. SGAs having only parent selection, crossover, and mutation are inefficient and rarely used for optimizing contaminant transport management. Even an advanced genetic algorithm (AGA) that includes elitism (to emphasize using the best strategies as parents) and healing (to help assure optimal strategy feasibility) is undesirably inefficient. Much more efficient than an AGA is the presented hybrid (AGCT), which adds comprehensive tabu search (TS) features to an AGA. TS mechanisms (TS probability, tabu list size, search coarseness and solution space size, and a TS threshold value) force the optimizer to search portions of the solution space that yield superior pumping strategies, and to avoid reproducing similar or inferior strategies. An AGCT characteristic is that TS control parameters are unchanging during optimization. However, TS parameter values that are ideal for optimization commencement can be undesirable when nearing assumed global optimality. The second presented hybrid, termed global converger (GC), is significantly better than the AGCT. GC includes AGCT plus feedback-driven auto-adaptive control that dynamically changes TS parameters during run-time. Before comparing AGCT and GC, we empirically derived scaled dimensionless TS control parameter guidelines by evaluating 50 sets of parameter values for a hypothetical optimization problem. For the hypothetical area, AGCT optimized both well locations and pumping rates. The parameters are useful starting values because using trial-and-error to identify an ideal combination of control parameter values for a new optimization problem can be time consuming. For comparison, AGA, AGCT, and GC are applied to optimize pumping rates for assumed well locations of a complex large-scale contaminant transport and remediation optimization problem at Blaine Naval Ammunition Depot (NAD). Both hybrid approaches converged more closely to the optimal solution than the non-hybrid AGA. GC averaged 18.79% better convergence than AGCT, and 31.9% than AGA, within the same computation time (12.5 days). AGCT averaged 13.1% better convergence than AGA. The GC can significantly reduce the burden of employing computationally intensive hydrologic simulation models within a limited time period and for real-world optimization problems. Although demonstrated for a groundwater quality problem, it is also applicable to other arenas, such as managing salt water intrusion and surface water contaminant loading.

The Perceptions of the Preparedness of Medical Graduates to Take on Internship Responsibilities in Low Resource Hospitals in Kenya

ERIC Educational Resources Information Center

Muthaura, Patricia N.; Khamis, Tashmin K.

2013-01-01

The Aga Khan University is developing an Undergraduate Medical Education (UGME) curriculum for implementation in East Africa in 2016, which aims to serve the health needs of the populations there. Pilot focus group discussions of recent interns were conducted at the Aga Khan University Hospital, Nairobi to find out: (1) If Kenyan medical students…

[Growth patterns of appropriate for gestational age infants of gestational diabetic mothers during the first year].

PubMed

Zhao, Y L; Ma, R M; Zhang, Y; Mo, Y X; Chen, Z; Sun, Y H; Ding, Z B

2016-08-02

To explore the growth pattern of appropriate for gestational age (AGA) infants of mother with gestational diabetes mellitus (GDM). The objects of this study were offspring of women who delivered in our hospital from January to December 2011. The GDM group included 70 AGA infants (36 male cases and 34 female cases) of mother with GDM. The control group included 154 AGA infants (66 male cases and 88 female cases) of women with normal glucose tolerance. The data of demographic characteristics of mothers of two groups were collected. Body weight and length of infants in two groups were measured at 3, 6 and 12 months age respectively. Body mass index (BMI), weight and height gain during infancy (0-3 months, 3-6 months and 6-12 months) of infants in two groups were also calculated. Body weight, length and BMI of male AGA infants in GDM group were less than that of control group at 3 months and 6 months age, but more than that of control group at 12 months age, however, there were no significant differences between two group(P>0.05). The weight and height gain during infancy (0-3 months, 3-6 months) of male AGA infants in GDM group were lower than that of control group, but the difference was statistically significant only at 3-6 months[(1.1±0.4) vs (1.4±0.4) kg, P=0.040; (4.9±2.3) vs (6.3±1.2) cm, P=0.026]. The weight and height gain during infancy (6-12 months) of male AGA infants of gestational diabetic mothers were higher than that of control group, but the difference was not statistically significant[(2.1±0.5) vs (1.8±0.5) kg, P=0.361; (8.4±1.3) vs (7.8±1.4) cm, P=0.464]. Male infants of gestational diabetic mothers grew slowly during their infancy of 0-6 months, and then their growth became increasingly fast, which suggested that the influence of intrauterine hyperglycemia environment of GDM mothers on fetal growth might continue after birth.

The role of sexual vs. asexual recruitment of Artemisia wudanica in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

NASA Astrophysics Data System (ADS)

Wang, Yongcui; Alberto, Busso Carlos; Jiang, Deming; Ala, Musa; Li, Xuehua; Zhou, Quanlai; Lin, Jixiang; Ren, Guohua; Jia, Lian

2016-04-01

Artemisia wudanica is an endemic, perennial, pioneering psammophyte species in the sand dune ecosystems of western Horqin Sand Land in northern China. However, no studies have addressed how sexual and asexual reproduction modes of A. wudanica perform at the transitional zones between active dune inter-dune lowlands and active dunes. In early spring, quadrats were randomly set up in the study area to monitor surviving seedling and/or ramet density and frequency coming from sexual/asexual reproduction of A. wudanica. Iron sticks were inserted near each quadrat to determine wind erosion intensity (WE). Additionally, soil samples were collected nearby each quadrat to test for soil moisture (SM), organic matter (OM) and pH. Surviving seedlings of A. wudanica showed an inverse response in comparison with ramets to SM, OM and WE. Soil moisture showed the most positive effect, and WE the negative effect, on surviving, sexual reproduction seedlings. Contrarily, WE had the most positive effect, and SM the negative effect, on asexual reproduction ramets. This suggests that increases in SM and decreases in WE should benefit recruitment of A. wudanica seedlings. On the contrary, ramets coming from asexual reproduction showed a different response to environmental factors in transition zone habitats. While SM was not a key constraint for the survival of seedlings, they showed a better, positive response to wind erosion environments. Overall, various study environmental parameters could be improved to foster A. wudanica invasion and settlement in the plant community through different reproductive modes, thereby promoting vegetation restoration and rehabilitation.

Diapause and maintenance of facultative sexual reproductive strategies

PubMed Central

Lehtonen, Jussi

2016-01-01

Facultative sex combines sexual and asexual reproduction in the same individual (or clone) and allows for a large diversity of life-history patterns regarding the timing, frequency and intensity of sexual episodes. In addition, other life-history traits such as a diapause stage may become linked to sex. Here, we develop a matrix modelling framework for addressing the cost of sex in facultative sexuals, in constant, periodic and stochastically fluctuating environments. The model is parametrized using life-history data from Brachionus calyciflorus, a facultative sexual rotifer in which sex and diapause are linked. Sexual propensity was an important driver of costs in constant environments, in which high costs (always > onefold, and sometimes > twofold) indicated that asexuals should outcompete facultative sexuals. By contrast, stochastic environments with high temporal autocorrelation favoured facultative sex over obligate asex, in particular, if the penalty to fecundity in ‘bad’ environments was large. In such environments, obligate asexuals were constrained by their life cycle length (i.e. time from birth to last reproductive adult age class), which determined an upper limit to the number of consecutive bad periods they could tolerate. Nevertheless, when facultative asexuals with different sexual propensities competed simultaneously against each other and asex, the lowest sex propensity was the most successful in stochastic environments with positive autocorrelation. Our results suggest that a highly specific mechanism (i.e. diapause linked to sex) can alone stabilize facultative sex in these animals, and protect it from invasion of both asexual and pure sexual strategies. This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’. PMID:27619700

The chastity of amoebae: re-evaluating evidence for sex in amoeboid organisms

PubMed Central

Lahr, Daniel J. G.; Parfrey, Laura Wegener; Mitchell, Edward A. D.; Katz, Laura A.; Lara, Enrique

2011-01-01

Amoebae are generally assumed to be asexual. We argue that this view is a relict of early classification schemes that lumped all amoebae together inside the ‘lower’ protozoa, separated from the ‘higher’ plants, animals and fungi. This artificial classification allowed microbial eukaryotes, including amoebae, to be dismissed as primitive, and implied that the biological rules and theories developed for macro-organisms need not apply to microbes. Eukaryotic diversity is made up of 70+ lineages, most of which are microbial. Plants, animals and fungi are nested among these microbial lineages. Thus, theories on the prevalence and maintenance of sex developed for macro-organisms should in fact apply to microbial eukaryotes, though the theories may need to be refined and generalized (e.g. to account for the variation in sexual strategies and prevalence of facultative sex in natural populations of many microbial eukaryotes). We use a revised phylogenetic framework to assess evidence for sex in several amoeboid lineages that are traditionally considered asexual, and we interpret this evidence in light of theories on the evolution of sex developed for macro-organisms. We emphasize that the limited data available for many lineages coupled with natural variation in microbial life cycles overestimate the extent of asexuality. Mapping sexuality onto the eukaryotic tree of life demonstrates that the majority of amoeboid lineages are, contrary to popular belief, anciently sexual, and that most asexual groups have probably arisen recently and independently. Additionally, several unusual genomic traits are prevalent in amoeboid lineages, including cyclic polyploidy, which may serve as alternative mechanisms to minimize the deleterious effects of asexuality. PMID:21429931

Benefits of a Recombination-Proficient Escherichia coli System for Adaptive Laboratory Evolution.

PubMed

Peabody, George; Winkler, James; Fountain, Weston; Castro, David A; Leiva-Aravena, Enzo; Kao, Katy C

2016-11-15

Adaptive laboratory evolution typically involves the propagation of organisms asexually to select for mutants with the desired phenotypes. However, asexual evolution is prone to competition among beneficial mutations (clonal interference) and the accumulation of hitchhiking and neutral mutations. The benefits of horizontal gene transfer toward overcoming these known disadvantages of asexual evolution were characterized in a strain of Escherichia coli engineered for superior sexual recombination (genderless). Specifically, we experimentally validated the capacity of the genderless strain to reduce the mutational load and recombine beneficial mutations. We also confirmed that inclusion of multiple origins of transfer influences both the frequency of genetic exchange throughout the chromosome and the linkage of donor DNA. We built a simple kinetic model to estimate recombination frequency as a function of transfer size and relative genotype enrichment in batch transfers; the model output correlated well with the experimental data. Our results provide strong support for the advantages of utilizing the genderless strain over its asexual counterpart during adaptive laboratory evolution for generating beneficial mutants with reduced mutational load. Over 80 years ago Fisher and Muller began a debate on the origins of sexual recombination. Although many aspects of sexual recombination have been examined at length, experimental evidence behind the behaviors of recombination in many systems and the means to harness it remain elusive. In this study, we sought to experimentally validate some advantages of recombination in typically asexual Escherichia coli and determine if a sexual strain of E. coli can become an effective tool for strain development. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Benefits of a Recombination-Proficient Escherichia coli System for Adaptive Laboratory Evolution

PubMed Central

Peabody, George; Winkler, James; Fountain, Weston; Castro, David A.; Leiva-Aravena, Enzo

2016-01-01

ABSTRACT Adaptive laboratory evolution typically involves the propagation of organisms asexually to select for mutants with the desired phenotypes. However, asexual evolution is prone to competition among beneficial mutations (clonal interference) and the accumulation of hitchhiking and neutral mutations. The benefits of horizontal gene transfer toward overcoming these known disadvantages of asexual evolution were characterized in a strain of Escherichia coli engineered for superior sexual recombination (genderless). Specifically, we experimentally validated the capacity of the genderless strain to reduce the mutational load and recombine beneficial mutations. We also confirmed that inclusion of multiple origins of transfer influences both the frequency of genetic exchange throughout the chromosome and the linkage of donor DNA. We built a simple kinetic model to estimate recombination frequency as a function of transfer size and relative genotype enrichment in batch transfers; the model output correlated well with the experimental data. Our results provide strong support for the advantages of utilizing the genderless strain over its asexual counterpart during adaptive laboratory evolution for generating beneficial mutants with reduced mutational load. IMPORTANCE Over 80 years ago Fisher and Muller began a debate on the origins of sexual recombination. Although many aspects of sexual recombination have been examined at length, experimental evidence behind the behaviors of recombination in many systems and the means to harness it remain elusive. In this study, we sought to experimentally validate some advantages of recombination in typically asexual Escherichia coli and determine if a sexual strain of E. coli can become an effective tool for strain development. PMID:27613685

Geographic parthenogenesis and plant-enemy interactions in the common dandelion

PubMed Central

2013-01-01

Background Many species with sexual and asexual variants show a pattern of geographic parthenogenesis where asexuals have broader and higher-latitude distribution than sexuals. Because sexual reproduction is often considered a costly evolutionary strategy that is advantageous in the face of selection by coevolving pests and pathogens, one possible explanation for geographic parthenogenesis is that populations at higher latitudes are exposed to fewer pests and pathogens. We tested this hypothesis in the common dandelion (Taraxacum officinale), a species with well-established geographic parthenogenesis, by screening prevalence and effects of several specialized pests and pathogens in natural dandelion populations. Results We did a population survey of 18 dandelion populations along a geographic transect that ranged from the area where sexual and asexual dandelions co-occur northward into the area where only asexuals occur. In addition we used four southern and four northern populations in a 8x8 cross-inoculation greenhouse experiment in which plants were exposed experimentally to each other’s natural field soil microbial communities. The cross-inoculation experiment indicated a higher pathogenicity of soil microbial communities from the southern, mostly sexual, populations compared to soil microbial communities from the northern asexual populations. Northern dandelion populations also showed reduced infestation by a specialized seed-eating weevil. A similar trend of reduced rust fungus infection in northern populations was observed but this trend was not statistically significant. Conclusions The prevalence of pests and pathogens decreased along the south-to-north axis of geographic parthenogenesis. This highlights the potential of biotic interactions in shaping patterns of geographic parthenogenesis. PMID:23356700

Intraspecific competition facilitates the evolution of tolerance to insect damage in the perennial plant Solanum carolinense.

PubMed

McNutt, David W; Halpern, Stacey L; Barrows, Kahaili; Underwood, Nora

2012-12-01

Tolerance to herbivory (the degree to which plants maintain fitness after damage) is a key component of plant defense, so understanding how natural selection and evolutionary constraints act on tolerance traits is important to general theories of plant-herbivore interactions. These factors may be affected by plant competition, which often interacts with damage to influence trait expression and fitness. However, few studies have manipulated competitor density to examine the evolutionary effects of competition on tolerance. In this study, we tested whether intraspecific competition affects four aspects of the evolution of tolerance to herbivory in the perennial plant Solanum carolinense: phenotypic expression, expression of genetic variation, the adaptive value of tolerance, and costs of tolerance. We manipulated insect damage and intraspecific competition for clonal lines of S. carolinense in a greenhouse experiment, and measured tolerance in terms of sexual and asexual fitness components. Compared to plants growing at low density, plants growing at high density had greater expression of and genetic variation in tolerance, and experienced greater fitness benefits from tolerance when damaged. Tolerance was not costly for plants growing at either density, and only plants growing at low density benefited from tolerance when undamaged, perhaps due to greater intrinsic growth rates of more tolerant genotypes. These results suggest that competition is likely to facilitate the evolution of tolerance in S. carolinense, and perhaps in other plants that regularly experience competition, while spatio-temporal variation in density may maintain genetic variation in tolerance.

A multigenerational effect of parental age on offspring size but not fitness in common duckweed (Lemna minor).

PubMed

Barks, P M; Laird, R A

2016-04-01

Classic theories on the evolution of senescence make the simplifying assumption that all offspring are of equal quality, so that demographic senescence only manifests through declining rates of survival or fecundity. However, there is now evidence that, in addition to declining rates of survival and fecundity, many organisms are subject to age-related declines in the quality of offspring produced (i.e. parental age effects). Recent modelling approaches allow for the incorporation of parental age effects into classic demographic analyses, assuming that such effects are limited to a single generation. Does this 'single-generation' assumption hold? To find out, we conducted a laboratory study with the aquatic plant Lemna minor, a species for which parental age effects have been demonstrated previously. We compared the size and fitness of 423 laboratory-cultured plants (asexually derived ramets) representing various birth orders, and ancestral 'birth-order genealogies'. We found that offspring size and fitness both declined with increasing 'immediate' birth order (i.e. birth order with respect to the immediate parent), but only offspring size was affected by ancestral birth order. Thus, the assumption that parental age effects on offspring fitness are limited to a single generation does in fact hold for L. minor. This result will guide theorists aiming to refine and generalize modelling approaches that incorporate parental age effects into evolutionary theory on senescence. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Discourses Governing Lesbian, Gay, Bisexual, Transgender, Queer, Intersex, and Asexual Teachers' Disclosure of Sexual Orientation and Gender History

ERIC Educational Resources Information Center

Bower-Phipps, Laura

2017-01-01

Significant progress has been made in equal rights for lesbian, gay, bisexual, transgender, queer, intersex, and asexual (LGBTQIA) individuals, yet schools remain institutions where sexual and gender diversity are marginalized and/or silenced. Queer theory, a non-linear theory that disrupts dominant beliefs about gender and sexuality and what…

Cyclical parthenogenesis and viviparity in aphids as evolutionary novelties.

PubMed

Davis, Gregory K

2012-09-01

Evolutionary novelties represent challenges to biologists, particularly those who would like to understand the developmental and genetic changes responsible for their appearance. Most modern aphids possess two apparent evolutionary novelties: cyclical parthenogenesis (a life cycle with both sexual and asexual phases) and viviparity (internal development and live birth of progeny) in their asexual phase. Here I discuss the evolution of these apparent novelties from a developmental standpoint. Although a full understanding of the evolution of cyclical parthenogenesis and viviparity in aphids can seem a daunting task, these complex transitions can at least be broken down into a handful of steps. I argue that these should include the following: a differentiation of two developmentally distinct oocytes; de novo synthesis of centrosomes and modification of meiosis during asexual oogenesis; a loss or bypass of any cell cycle arrest and changes in key developmental events during viviparous oogenesis; and a change in how mothers specify the sexual vs. asexual fates of their progeny. Grappling with the nature of such steps and the order in which they occurred ought to increase our understanding and reduce the apparent novelty of complex evolutionary transitions. © 2012 Wiley Periodicals, Inc.

In Vitro Activities of Primaquine-Schizonticide Combinations on Asexual Blood Stages and Gametocytes of Plasmodium falciparum

PubMed Central

Cabrera, Mynthia

2015-01-01

Currently, the World Health Organization recommends addition of a 0.25-mg base/kg single dose of primaquine (PQ) to artemisinin combination therapies (ACTs) for Plasmodium falciparum malaria as a gametocytocidal agent for reducing transmission. Here, we investigated the potential interactions of PQ with the long-lasting components of the ACT drugs for eliminating the asexual blood stages and gametocytes of in vitro-cultured P. falciparum strains. Using the SYBR green I assay for asexual parasites and a flow cytometry-based assay for gametocytes, we determined the interactions of PQ with the schizonticides chloroquine, mefloquine, piperaquine, lumefantrine, and naphthoquine. With the sums of fractional inhibitory concentrations and isobolograms, we were able to determine mostly synergistic interactions for the various PQ and schizonticide combinations on the blood stages of P. falciparum laboratory strains. The synergism in inhibiting asexual stages and gametocytes was highly evident with PQ-naphthoquine, whereas synergism was moderate for the PQ-piperaquine, PQ-chloroquine, and PQ-mefloquine combinations. We have detected potentially antagonistic interactions between PQ and lumefantrine under certain drug combination ratios, suggesting that precautions might be needed when PQ is added as the gametocytocide to the artemether-lumefantrine ACT (Coartem). PMID:26416869

Genome structure of bdelloid rotifers: shaped by asexuality or desiccation?

PubMed

Gladyshev, Eugene A; Arkhipova, Irina R

2010-01-01

Bdelloid rotifers are microscopic invertebrate animals best known for their ancient asexuality and the ability to survive desiccation at any life stage. Both factors are expected to have a profound influence on their genome structure. Recent molecular studies demonstrated that, although the gene-rich regions of bdelloid genomes are organized as colinear pairs of closely related sequences and depleted in repetitive DNA, subtelomeric regions harbor diverse transposable elements and horizontally acquired genes of foreign origin. Although asexuality is expected to result in depletion of deleterious transposons, only desiccation appears to have the power to produce all the uncovered genomic peculiarities. Repair of desiccation-induced DNA damage would require the presence of a homologous template, maintaining colinear pairs in gene-rich regions and selecting against insertion of repetitive DNA that might cause chromosomal rearrangements. Desiccation may also induce a transient state of competence in recovering animals, allowing them to acquire environmental DNA. Even if bdelloids engage in rare or obscure forms of sexual reproduction, all these features could still be present. The relative contribution of asexuality and desiccation to genome organization may be clarified by analyzing whole-genome sequences and comparing foreign gene and transposon content in species which lost the ability to survive desiccation.

First real-time observation of transverse division in azooxanthellate scleractinian corals

PubMed Central

Tokuda, Yuki; Haraguchi, Hiroko; Ezaki, Yoichi

2017-01-01

Asexual reproduction is one of the most important traits in the evolutionary history of corals. No real-time observations of asexual reproduction in azooxanthellate solitary scleractinian corals have been conducted to date. Here, we describe previously unknown aspects of asexual reproduction by using Truncatoflabellum spheniscus (Family Flabellidae) based on observations of transverse division conducted over 1200 days. The findings revealed that (1) transverse division was caused by decalcification; (2) compared to the anthocyathus (upper part of the divided corallum), the soft parts of the anthocaulus (lower part of the divided corallum) were severely damaged and injured during division; (3) these injuries were repaired rapidly; and (4) the anthocaulus regrew and repeatedly produced anthocyathi by means of transverse division. Differences in the patterns of soft-part regeneration and repair, as well as differences in skeletal growth rates between the anthocaulus and the anthocyathus imply that the ecological requirements and reproductive success are different from each other immediately after division. The findings provide important clues for unravelling why asexual reproduction appeared frequently in free-living corals, and the extent to which those modes of reproduction has affected the adaptive and evolutionary success of scleractinian corals throughout the Phanerozoic. PMID:28150745

First real-time observation of transverse division in azooxanthellate scleractinian corals

NASA Astrophysics Data System (ADS)

Tokuda, Yuki; Haraguchi, Hiroko; Ezaki, Yoichi

2017-02-01

Asexual reproduction is one of the most important traits in the evolutionary history of corals. No real-time observations of asexual reproduction in azooxanthellate solitary scleractinian corals have been conducted to date. Here, we describe previously unknown aspects of asexual reproduction by using Truncatoflabellum spheniscus (Family Flabellidae) based on observations of transverse division conducted over 1200 days. The findings revealed that (1) transverse division was caused by decalcification; (2) compared to the anthocyathus (upper part of the divided corallum), the soft parts of the anthocaulus (lower part of the divided corallum) were severely damaged and injured during division; (3) these injuries were repaired rapidly; and (4) the anthocaulus regrew and repeatedly produced anthocyathi by means of transverse division. Differences in the patterns of soft-part regeneration and repair, as well as differences in skeletal growth rates between the anthocaulus and the anthocyathus imply that the ecological requirements and reproductive success are different from each other immediately after division. The findings provide important clues for unravelling why asexual reproduction appeared frequently in free-living corals, and the extent to which those modes of reproduction has affected the adaptive and evolutionary success of scleractinian corals throughout the Phanerozoic.

Department of National Defence's use of thermography for facilities maintenance

NASA Astrophysics Data System (ADS)

Kittson, John E.

1990-03-01

Since the late seventies DND through the Director General Works has been actively encouraging the use of thermography as an efficient and effective technique for supporting preventive maintenance quality assurance and energy conservation programs at Canadian Forces Bases (CFBs). This paper will provide an overview of DND''s experiences in the utilization of thermography for facilities maintenance applications. 1. HISTORICAL MILESTONES The following are milestones of DND''s use of thermography: a. Purchase of Infrared Equipment In 1976/77 DND purchased five AGA 750 Infrared Thermovision Systems which were distributed to commands. In 1980/81/82 six AGA liOs five AGA TPT8Os two AGA 782s and one AGA 720 were acquired. Finally DND also purchased seven AGEMA 870 systems during 1987/88. b. First and Second Interdepartaental Building Thermography Courses In 1978 and 1980 DND hosted two building thermography courses that were conducted by Public Works Canada. c. CE Thermographer Specialist Training Courses DND developed a training standard in 1983 for Construction Engineering (CE) Thermographer qualification which included all CE applications of thermography. The first annual inhouse training course was conducted at CFB Borden Ontario in 1984. These are now being conducted at the CFB Chilliwack Detachment in Vernon British Columbia. 2 . MARKETING FACILITIES MAINTENANCE IR Of paramount importance for successfully developing DND appreciation for thermography was providing familiarization training to CE staff at commands and bases. These threeday presentations emphasized motivational factors conducting thermographic surveys and utilizing infrared data of roofs electrical/mechanical systems heating plants steam distribution and building enclosures. These factors consisted mainly of the following objectives: a. preventive maintenance by locating deficiencies to be repaired b. quality assurance by verification of workmanship materials and design c. energy conservation by locating heat loss areas 2 / SPIE Vol. 1313 Thermosense XII (1990)

Prescribing Habits for Androgenic Alopecia Among Dermatologists in Spain in 2017: A Cross-Sectional Study.

PubMed

Pindado-Ortega, C; Saceda-Corralo, D; Buendía-Castaño, D; Fernández-González, P; Moreno-Arrones, Ó M; Fonda-Pascual, P; Alegre-Sánchez, A; Rodrigues-Barata, A R; Vañó-Galván, S

2018-04-12

Topical minoxidil and oral finasteride are the only drugs approved for the treatment of androgenetic alopecia (AGA) in Spain. However, the management of this condition is highly variable because numerous treatments are used off-label. The main aim of this study was to describe the prescribing habits of dermatologists in Spain for male AGA (MAGA) and female AGA (FAGA). Descriptive cross-sectional study using online questionnaires completed by dermatologists working in Spain. The responses of 241 dermatologists were analyzed. The most common treatments prescribed for MAGA were minoxidil (98%), oral finasteride (96%), nutricosmetics (44%), topical finasteride (37%), oral dutasteride (33%), platelet-rich plasma (14%), and low-level laser therapy (8%). For premenopausal FAGA, the most common treatments were topical minoxidil (98%), oral contraceptives (81%), nutricosmetics (72%), cyproterone acetate (58%), oral finasteride (39%), topical finasteride (39%), spironolactone (27%), platelet-rich plasma (20%), oral dutasteride (20%), oral flutamide (18%), and low-level laser therapy (7%). Finally, for postmenopausal FAGA, the most common treatments prescribed were topical minoxidil (98%), oral finasteride (84%), nutricosmetics (68%), topical finasteride (50%), oral dutasteride (35%), platelet-rich plasma (21%), spironolactone (16%), cyproterone acetate (16%), oral flutamide (9%), and low-level laser therapy (9%). A limitation of our study is that we did not analyze novel AGA treatments such as oral minoxidil and dutasteride mesotherapy. The most common treatments prescribed for AGA by dermatologists in Spain are topical minoxidil, oral finasteride, and nutricosmetics for MAGA and postmenopausal FAGA and topical minoxidil, oral contraceptives, and nutricosmetics for premenopausal FAGA. Copyright © 2018 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.

Variations in Health Insurance Policies Regarding Biologic Therapy Use in Inflammatory Bowel Disease.

PubMed

Yadav, Abhijeet; Foromera, Joshua; Feuerstein, Ilana; Falchuk, Kenneth R; Feuerstein, Joseph D

2017-06-01

The American Gastroenterological Association (AGA) has developed guidelines for the management of ulcerative colitis and Crohn's disease (CD) recommending anti-TNF therapy in moderate-severe disease. However, which drug is used is often dictated by insurance company policies. We sought to determine the insurance policy requirements prior to approval of biologic therapies. Using the National Association of Insurance Commissioners report of the top 125 insurance companies by market share in 2014, we reviewed the first 50 that had online policies regarding anti-TNF and vedolizumab available. Policies were reviewed for criteria needed for approval of anti-TNF or vedolizumab therapy, and for compliance with the current AGA clinical pathway recommendations. Ninety-eight percent of policies are inconsistent with the AGA ulcerative colitis pathway and require step-wise drug failure before approval of an anti-TNF. Only 11% of the policies allowed starting vedolizumab without initial failures of an anti-TNF agent, and 21% required the failure of two or more anti-TNF agents. Ninety percent of the policies are inconsistent with AGA CD pathway and require step-wise drug failure before approval of an anti-TNF. Seventy-four percent allowed for initiating infliximab specifically for fistulizing CD. Twenty-eight percent required failing of at least two or more drugs before starting anti-TNF. Only 8% policies allowed starting vedolizumab without initial failures of an anti-TNF agent, and 28% required the failure of two anti-TNF agents. The majority of the policies reviewed fail to adhere to the current AGA pathway recommendations for ulcerative colitis and CD. Further interventions are needed to better align policies with optimal evidence-based drug therapy.

Association of stress with anxiety and depression during pregnancy.

PubMed

Gul, Fouzia; Sherin, Akhtar; Jabeen, Mussarrat; Khan, Shajaat Ali

2017-12-01

To find out the association of stress with anxiety and depression during pregnancy and to identify common stressors in women. This cross-sectional study was conducted at Divisional Headquarters Teaching Hospital, Kohat, Pakistan, from February 2011 to October 2012, and comprised pregnant women. Convenient sampling technique was used. The participants were administered Urdu-translated version of A-Z perceived stress scale and Aga Khan University anxiety and depression scale. Women with a score of >19 on the Aga Khan University scale were labelled as anxious and depressed. Data was collected on a pre-designed proforma. SPSS 17 was used for data analysis. There were 500 participants with an overall mean age of 28.3±6.3 years. The overall mean stress score on A-Z perceived stress scale was 12.93±5.19 and mean Aga Khan University anxiety and depression scale score was 28.58±13.82. Mean A-Z score was 14.18±4.881 in women with anxiety-depression and 9.75±4.58 in non-depressed women (p<0.001). Mean Aga Khan score in women with >10 stressors was significantly higher (32.18±13.79) compared to women with <10 stressors (19.87±9.30) (p<0.01). A-Z stressors score had significant positive correlation with the Aga Khan scale (p<0.001]. The most common stressors were concern about husband's worries and concern about feeling unwell during pregnancy, present in 433(86.6%) patients each, followed by concern about increase in the prices of everyday goods which was present in 364(72.8%) patients. The magnitude of stress was significantly associated with high anxiety and depression during pregnancy.

[Effects of postnatal growth retardation on early neurodevelopment in premature infants with intrauterine growth retardation].

PubMed

Cai, Yue-Ju; Song, Yan-Yan; Huang, Zhi-Jian; Li, Jian; Qi, Jun-Ye; Xiao, Xu-Wen; Wang, Lan-Xiu

2015-09-01

To study the effects of postnatal growth retardation on early neurodevelopment in premature infants with intrauterine growth retardation (IUGR). A retrospective analysis was performed on the clinical data of 171 premature infants who were born between May 2008 and May 2012 and were followed up until a corrected gestational age of 6 months. These infants were classified into two groups: IUGR group (n=40) and appropriate for gestational age (AGA) group (n=131). The growth retardation rates at the corrected gestational ages of 40 weeks, 3 months, and 6 months, as well as the neurodevelopmental outcome (evaluated by Gesell Developmental Scale) at corrected gestational ages of 3 and 6 months, were compared between the two groups. The growth retardation rate in the IUGR group was significantly higher than in the AGA group at the corrected gestational ages of 40 weeks, 3 months, and 6 months. All five developmental quotients evaluated by Gesell Developmental Scale (gross motor, fine motor, language, adaptability and individuality) in the IUGR group were significantly lower than in the AGA group at the corrected gestational ages of 3 months. At the corrected gestational age of 6 months, the developmental quotients of fine motor and language in the IUGR group were significantly lower than in the AGA group, however, there were no significant differences in the developmental quotients of gross motor, adaptability and individuality between the two groups. All five developmental quotients in IUGR infants with catch-up lag in weight were significantly lower than in IUGR and AGA infants who had caught up well. Growth retardation at early postnatal stages may adversely affect the early neurodevelopment in infants with IUGR.

Substrate Recognition and Hydrolysis by a Family 50 exo-β-Agarase, Aga50D, from the Marine Bacterium Saccharophagus degradans*

PubMed Central

Pluvinage, Benjamin; Hehemann, Jan-Hendrik; Boraston, Alisdair B.

2013-01-01

The bacteria that metabolize agarose use multiple enzymes of complementary specificities to hydrolyze the glycosidic linkages in agarose, a linear polymer comprising the repeating disaccharide subunit of neoagarobiose (3,6-anhydro-l-galactose-α-(1,3)-d-galactose) that are β-(1,4)-linked. Here we present the crystal structure of a glycoside hydrolase family 50 exo-β-agarase, Aga50D, from the marine microbe Saccharophagus degradans. This enzyme catalyzes a critical step in the metabolism of agarose by S. degradans through cleaving agarose oligomers into neoagarobiose products that can be further processed into monomers. The crystal structure of Aga50D to 1.9 Å resolution reveals a (β/α)8-barrel fold that is elaborated with a β-sandwich domain and extensive loops. The structures of catalytically inactivated Aga50D in complex with non-hydrolyzed neoagarotetraose (2.05 Å resolution) and neoagarooctaose (2.30 Å resolution) provide views of Michaelis complexes for a β-agarase. In these structures, the d-galactose residue in the −1 subsite is distorted into a 1S3 skew boat conformation. The relative positioning of the putative catalytic residues are most consistent with a retaining catalytic mechanism. Additionally, the neoagarooctaose complex showed that this extended substrate made substantial interactions with the β-sandwich domain, which resembles a carbohydrate-binding module, thus creating additional plus (+) subsites and funneling the polymeric substrate through the tunnel-shaped active site. A synthesis of these results in combination with an additional neoagarobiose product complex suggests a potential exo-processive mode of action of Aga50D on the agarose double helix. PMID:23921382

Distinguishing pathological from constitutional small for gestational age births in population-based studies.

PubMed

Ananth, Cande V; Vintzileos, Anthony M

2009-10-01

Small for gestational age (SGA) can occur following a pathological process or may represent constitutionally small fetuses. However, distinguishing these processes is often difficult, especially in large studies, where the term SGA is often used as a proxy for restricted fetal growth. Since biologic variation in fetal size is largely a third trimester phenomenon, we hypothesized that the definition of SGA at term may include a sizeable proportion of constitutionally small fetuses. In contrast, since biologic variation in fetal size is not fully expressed in (early) preterm gestations, it is plausible that SGA in early preterm gestations would comprise a large proportion of growth restricted fetuses. We compared mortality and morbidity rates between SGA and appropriate for gestational age (AGA) babies. A population-based study of over 19million non-malformed, singleton births (1995-04) in the United States was performed. Gestational age (24-44weeks) was based on a clinical estimate. SGA and AGA were defined as sex-specific birthweight <10th and 25-74th centiles, respectively, for gestational age. All analyses were adjusted for a variety of confounding factors. Excess mortality risk in SGA and AGA babies. On an additive scale, stillbirth and neonatal mortality rates were higher at every preterm gestation among SGA than AGA births, and similar at term gestations. An inverse relationship between gestational age and excess deaths between SGA and AGA babies delivered at <37weeks was evident. In early preterm gestations, the definition of SGA may well be justified as a proxy for IUGR. In contrast, SGA babies that are delivered at term are likely to be constitutionally small.

The use of low-level light therapy in the treatment of androgenetic alopecia and female pattern hair loss.

PubMed

Gupta, Aditya K; Daigle, Deanne

2014-04-01

Androgenetic alopecia (AGA) or female pattern hair loss (FPHL) is the most common form of hair loss in men and women. Despite its common occurrence, our understanding of the etiology of AGA and FPHL remains incomplete. As such, traditional therapies demonstrate modest efficacies and new therapies continue to be sought. Low-level light therapy (LLLT) is a relatively new technique used to promote hair growth in both men and women with AGA and FPHL. Currently, there exist several LLLT devices marketed for the treatment of alopecia, which claim to stimulate hair growth; yet marketing these devices only requires that safety, not efficacy, be established. A handful of studies have since investigated the efficacy of LLLT for alopecia with mixed results. These studies suffered from power, confounding and analysis issues which resulted in a high risk of bias in LLLT studies. Due to the paucity of well-conducted randomized controlled trials, the efficacy of LLLT devices remains unclear. Randomized controlled trials of LLLT conducted and reported according to the Consolidated Standards of Reporting Trials (CONSORT) statement would greatly increase the credibility of the evidence and clarify the ambiguity of the effectiveness of LLLT in the treatment of AGA and FPHL.

Use of Low-Level Laser Therapy as Monotherapy or Concomitant Therapy for Male and Female Androgenetic Alopecia

PubMed Central

Munck, Andréia; Gavazzoni, Maria Fernanda; Trüeb, Ralph M

2014-01-01

Background: Androgenetic alopecia (AGA) is the most common form of hair loss in men and in women. Currently, minoxidil and finasteride are the treatments with the highest levels of medical evidence, but patients who exhibit intolerance or poor response to these treatments are in need of additional treatment modalities. Objective: The aim was to evaluate the efficacy and safety of low-level laser therapy (LLLT) for AGA, either as monotherapy or as concomitant therapy with minoxidil or finasteride, in an office-based setting. Materials and Methods: Retrospective observational study of male and female patients with AGA, treated with the 655 nm-HairMax Laser Comb®, in an office-based setting. Efficacy was assessed with global photographic imaging. Results: Of 32 patients (21 female, 11 male), 8 showed significant, 20 moderate, and 4 no improvement. Improvement was seen both with monotherapy and with concomitant therapy. Improvement was observed as early as 3 months and was sustained up to a maximum observation time of 24 months. No adverse reactions were reported. Conclusions: LLLT represents a potentially effective treatment for both male and female AGA, either as monotherapy or concomitant therapy. Combination treatments with minoxidil, finasteride, and LLLT may act synergistic to enhance hair growth. PMID:25191036

Molecular cloning, characterization and enzymatic properties of a novel βeta-agarase from a marine isolate Psudoalteromonas SP. AG52

PubMed Central

Oh, Chulhong; Nikapitiya, Chamilani; Lee, Youngdeuk; Whang, Ilson; Kang, Do-Hyung; Heo, Soo-Jin; Choi, Young-Ung; Lee, Jehee

2010-01-01

An agar-degrading Pseudoalteromonas sp. AG52 bacterial strain was identified from the red seaweed Gelidium amansii collected from Jeju Island, Korea. A β-agarase gene which has 96.8% nucleotide identity to Aeromonas β-agarase was cloned from this strain, and was designated as agaA. The coding region is 870 bp, encoding 290 amino acids and possesses characteristic features of the glycoside hydrolase family (GHF)-16. The predicted molecular mass of the mature protein was 32 kDa. The recombinant β-agarase (rAgaA) was overexpressed in Escherichia coli and purified as a fusion protein. The optimal temperature and pH for activity were 55 °C and 5.5, respectively. The enzyme had a specific activity of 105.1 and 79.5 unit/mg toward agar and agarose, respectively. The pattern of agar hydrolysis demonstrated that the enzyme is an endo-type β-agarase, producing neoagarohexaose and neoagarotetraose as the final main products. Since, Pseudoalteromonas sp. AG52 encodes an agaA gene, which has greater identity to Aeromonas β-agarase, the enzyme could be considered as novel, with its unique bio chemical characteristics. Altogether, the purified rAgaA has potential for use in industrial applications such as development of cosmetics and pharmaceuticals. PMID:24031567

Low-level light therapy for androgenetic alopecia: a 24-week, randomized, double-blind, sham device-controlled multicenter trial.

PubMed

Kim, Hyojin; Choi, Jee Woong; Kim, Jun Young; Shin, Jung Won; Lee, Seok-Jong; Huh, Chang-Hun

2013-08-01

Androgenetic alopecia (AGA) is a common disorder affecting men and women. Finasteride and minoxidil are well-known, effective treatment methods, but patients who exhibit a poor response to these methods have no additional adequate treatment modalities. To evaluate the efficacy and safety of a low-level light therapy (LLLT) device for the treatment of AGA. This study was designed as a 24-week, randomized, double-blind, sham device-controlled trial. Forty subjects with AGA were enrolled and scheduled to receive treatment with a helmet-type, home-use LLLT device emitting wavelengths of 630, 650, and 660 nm or a sham device for 18 minutes daily. Investigator and subject performed phototrichogram assessment (hair density and thickness) and global assessment of hair regrowth for evaluation. After 24 weeks of treatment, the LLLT group showed significantly greater hair density than the sham device group. Mean hair diameter improved statistically significantly more in the LLLT group than in the sham device group. Investigator global assessment showed a significant difference between the two groups, but that of the subject did not. No serious adverse reactions were detected. LLLT could be an effective treatment for AGA. © 2013 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

Female-patterned alopecia in teenage brothers with unusual histologic features.

PubMed

Carlson, J Andrew; Malysz, Jozef; Schwartz, Joseph

2006-11-01

Patterned hair loss, follicular miniaturization, and increased telogen hair counts characterize androgenic alopecia (AGA). Follicular inflammation in AGA has been associated with treatment resistance and progressive hair loss. Brothers, 15 and 18 years old, presented with frontal and mid-scalp hair loss with an intact frontal hairline noted over a 1-year period. The elder reported past use of androgenic steroids. Laboratory assessment for metabolic and hormonal abnormalities was unrevealing, and hair pull test was negative. Scalp biopsies revealed decreased terminal hairs, marked diameter variation of anagen hairs, decreased terminal to vellus hair ratios (3.7:1/3.4:1, older/younger), and increased telogen counts (23%/21%). Infrabulbar and peri-isthmic (follicular bulge region) lymphocytic infiltrates were present. Hair loss has progressed, unabated by daily topical 0.5% clobetasol (for 6 months), daily 5% minoxidil (1 year), and latter, daily oral finasteride (2 years - older brother only). Based on patterned hair loss and miniaturized hairs, these brothers have AGA. The female pattern of hair loss (diffuse hair loss affecting the central scalp with preservation of frontal hair line) coupled with follicular isthmic lymphocytic inflammation represents an unusual presentation, possibly a treatment resistant, inflammatory variant of AGA. The differential diagnosis includes exogenous androgen-mediated hair loss, cicatricial pattern hair loss, or the superimposition of alopecia areata.

Asexual reproduction induces a rapid and permanent loss of sexual reproduction capacity in the rice fungal pathogen Magnaporthe oryzae: results of in vitro experimental evolution assays

PubMed Central

2012-01-01

Background Sexual reproduction is common in eukaryotic microorganisms, with few species reproducing exclusively asexually. However, in some organisms, such as fungi, asexual reproduction alternates with episodic sexual reproduction events. Fungi are thus appropriate organisms for studies of the reasons for the selection of sexuality or clonality and of the mechanisms underlying this selection. Magnaporthe oryzae, an Ascomycete causing blast disease on rice, reproduces mostly asexually in natura. Sexual reproduction is possible in vitro and requires (i) two strains of opposite mating types including (ii) at least one female-fertile strain (i.e. a strain able to produce perithecia, the female organs in which meiosis occurs). Female-fertile strains are found only in limited areas of Asia, in which evidence for contemporary recombination has recently been obtained. We induced the forced evolution of four Chinese female-fertile strains in vitro by the weekly transfer of asexual spores (conidia) between Petri dishes. We aimed to determine whether female fertility was rapidly lost in the absence of sexual reproduction and whether this loss was controlled genetically or epigenetically. Results All the strains became female-sterile after 10 to 19 rounds of selection under asexual conditions. As no single-spore isolation was carried out, the observed decrease in the production of perithecia reflected the emergence and the invasion of female-sterile mutants. The female-sterile phenotype segregated in the offspring of crosses between female-sterile evolved strains and female-fertile wild-type strains. This segregation was maintained in the second generation in backcrosses. Female-sterile evolved strains were subjected to several stresses, but none induced the restoration of female fertility. This loss of fertility was therefore probably due to genetic rather than epigenetic mechanisms. In competition experiments, female-sterile mutants produced similar numbers of viable conidia to wild-type strains, but released them more efficiently. This advantage may account for the invasion of our populations by female-sterile mutants. Conclusions We show for the first time that, in the absence of sexual reproduction, female-sterile mutants of M. oryzae rice strains can arise and increase in abundance in asexual generations. This change in phenotype was frequent and probably caused by mutation. These results suggest that female fertility may have been lost rapidly during the dispersion of the fungus from Asia to the rest of the world. PMID:22458778

Gonad establishment during asexual reproduction in the annelid Pristina leidyi.

PubMed

Özpolat, B Duygu; Bely, Alexandra E

2015-09-01

Animals that can reproduce by both asexual agametic reproduction and sexual reproduction must transmit or re-establish their germ line post-embryonically. Although such a dual reproductive mode has evolved repeatedly among animals, how asexually produced individuals establish their germ line remains poorly understood in most groups. We investigated germ line development in the annelid Pristina leidyi, a species that typically reproduces asexually by paratomic fission, intercalating a new tail and head in the middle of the body followed by splitting. We found that in fissioning individuals, gonads occur in anterior segments in the anterior-most individual as well as in new heads forming within fission zones. Homologs of the germ line/multipotency genes piwi, vasa, and nanos are expressed in the gonads, as well as in proliferative tissues including the posterior growth zone, fission zone, and regeneration blastema. In fissioning animals, certain cells on the ventral nerve cord express a homolog of piwi, are abundant near fission zones, and sometimes make contact with gonads. Such cells are typically undetectable near the blastema and posterior growth zone. Time-lapse imaging provides direct evidence that cells on the ventral nerve cord migrate preferentially towards fission zones. Our findings indicate that gonads form routinely in fissioning individuals, that a population of piwi-positive cells on the ventral nerve cord is associated with fission and gonads, and that cells resembling these piwi-positive cells migrate along the ventral nerve cord. We suggest that the piwi-positive ventral cells are germ cells that transmit the germ line across asexually produced individuals via migration along the ventral nerve cord. Copyright © 2015 Elsevier Inc. All rights reserved.

Evolutionary dynamics of phenotype-structured populations: from individual-level mechanisms to population-level consequences

NASA Astrophysics Data System (ADS)

Chisholm, Rebecca H.; Lorenzi, Tommaso; Desvillettes, Laurent; Hughes, Barry D.

2016-08-01

Epigenetic mechanisms are increasingly recognised as integral to the adaptation of species that face environmental changes. In particular, empirical work has provided important insights into the contribution of epigenetic mechanisms to the persistence of clonal species, from which a number of verbal explanations have emerged that are suited to logical testing by proof-of-concept mathematical models. Here, we present a stochastic agent-based model and a related deterministic integrodifferential equation model for the evolution of a phenotype-structured population composed of asexually-reproducing and competing organisms which are exposed to novel environmental conditions. This setting has relevance to the study of biological systems where colonising asexual populations must survive and rapidly adapt to hostile environments, like pathogenesis, invasion and tumour metastasis. We explore how evolution might proceed when epigenetic variation in gene expression can change the reproductive capacity of individuals within the population in the new environment. Simulations and analyses of our models clarify the conditions under which certain evolutionary paths are possible and illustrate that while epigenetic mechanisms may facilitate adaptation in asexual species faced with environmental change, they can also lead to a type of "epigenetic load" and contribute to extinction. Moreover, our results offer a formal basis for the claim that constant environments favour individuals with low rates of stochastic phenotypic variation. Finally, our model provides a "proof of concept" of the verbal hypothesis that phenotypic stability is a key driver in rescuing the adaptive potential of an asexual lineage and supports the notion that intense selection pressure can, to an extent, offset the deleterious effects of high phenotypic instability and biased epimutations, and steer an asexual population back from the brink of an evolutionary dead end.

Promising therapies for treating and/or preventing androgenic alopecia.

PubMed

McElwee, K J; Shapiro, J S

2012-06-01

Androgenetic alopecia (AGA) may affect up to 70% of men and 40% of women at some point in their lifetime. While men typically present with a distinctive alopecia pattern involving hairline recession and vertex balding, women normally exhibit a diffuse hair thinning over the top of their scalps. The treatment standard in dermatology clinics continues to be minoxidil and finasteride with hair transplantation as a surgical option. Here we briefly review current therapeutic options and treatments under active investigation. Dutasteride and ketoconazole are also employed for AGA, while prostaglandin analogues latanoprost and bimatoprost are being investigated for their hair growth promoting potential. Laser treatment products available for home use and from cosmetic clinics are becoming popular. In the future, new cell mediated treatment approaches may be available for AGA. While there are a number of potential treatment options, good clinical trial data proving hair growth efficacy is limited.

Gonadotropin levels in urine during early postnatal period in small for gestational age preterm male infants with fetal growth restriction.

PubMed

Nagai, S; Kawai, M; Myowa-Yamakoshi, M; Morimoto, T; Matsukura, T; Heike, T

2017-07-01

The objective of this study was to estimate gonadotropin concentrations in small for gestational age (SGA) male infants with the reactivation of the hypothalamic-pituitary-gonadal axis during the first few months of life that is important for genital development. We prospectively examined 15 SGA and 15 appropriate for gestational age (AGA) preterm male infants between 2013 and 2014 at Kyoto University Hospital. Gonadotropin concentrations (luteinizing hormone (LH) and follicle-stimulating hormone (FSH)) were measured in serial urine samples from the postnatal days 7 to 168 and compared between SGA and AGA infants using the Mann-Whitney test. A longitudinal analysis showed that SGA infants had higher LH and lower FSH concentrations (P=0.004 and P=0.006, respectively) than AGA infants. Male infants who are SGA at birth because of fetal growth restriction have gonadotropin secretion abnormalities in the first few months of life.

Variations of Human DNA Polymerase Genes as Biomarkers of Prostate Cancer Progression

DTIC Science & Technology

2011-07-01

Forward sequence Reverse sequence Sequence contextb 1 g.39835C4Tc P169S 15 25 gTG GGG TC CTT g.39897C4T Intronic 22 15 AGA T GGt TA AAT g.39985T4C...Intronic 34 25 AGA TT tAA AAG g.40051C4Tc P184S 19 34 TGt CT GGA ATT 4 g.39835C4Tc P169S 19 29 gTG GGG TC CTT g.40051C4Tc P184S 23 34 TGt CT GGA ATT 6 g...39835C4Tc P169S 14 24 gTG GGG TC CTT g.40051C4Tc P184S 21 32 TGt CT GGA ATT 11 g.40055A4G D185G 28 35 TTC C AGA C AAG g.40073A4G Y191C 28 20 gGA T AtG CC

Asexual-sexual morph connection in the type species of Berkleasmium.

PubMed

Tanney, Joey; Miller, Andrew N

2017-06-01

Berkleasmium is a polyphyletic genus comprising 37 dematiaceous hyphomycetous species. In this study, independent collections of the type species, B. concinnum , were made from Eastern North America. Nuclear internal transcribed spacer rDNA (ITS) and partial nuc 28S large subunit rDNA (LSU) sequences obtained from collections and subsequent cultures showed that Berkleasmium concinnum is the asexual morph of Neoacanthostigma septoconstrictum ( Tubeufiaceae , Tubeufiales ). Phylogenies inferred from Bayesian inference and maximum likelihood analyses of ITS-LSU sequence data confirmed this asexual-sexual morph connection and a re-examination of fungarium reference specimens also revealed the co-occurrence of N. septoconstrictum ascomata and B. concinnum sporodochia. Neoacanthostigma septoconstrictum is therefore synonymized under B. concinnum on the basis of priority. A specimen identified as N. septoconstrictum from Thailand is described as N. thailandicum sp. nov., based on morphological and genetic distinctiveness.

Testing a Hypothesis for the Evolution of Sex

NASA Astrophysics Data System (ADS)

Örçal, Bora; Tüzel, Erkan; Sevim, Volkan; Jan, Naeem; Erzan, Ayşe.

An asexual set of primitive bacteria is simulated with a bit-string Penna model with a Fermi function for survival. A recent hypothesis by Jan, Stauffer, and Moseley on the evolution of sex from asexual cells as a strategy for trying to escape the effects of deleterious mutations is checked. This strategy is found to provide a successful scenario for the evolution of a stable macroscopic sexual population.

Differential evolution of asexual and sexual females in a benign culture environment

PubMed Central

Snell, Terry W.

2013-01-01

Here we report one of the first investigations of evolvability of lifespan and reproduction in metazoans, examining both extrinsic and intrinsic factors. We tested effects on senescence of an environmental variable (simulated lake hydroperiod, the length of time an aquatic habitat is inundated), female reproductive physiology (asexual females that reproduce by ameiosis, versus sexual females reproducing by meiosis), and time in a benign culture environment (minimal, if any, external mortality factors). To do this we established chemostat cultures of the rotifer Brachionus plicatilis s.s., and maintained the cultures for 385 d. Hydroperiod alone or in interaction with the effects of time in the benign environment (season) or reproductive physiology had no significant effect on the net reproductive rate, generation time, or rate of aging. Yet combining animals from both ephemeral and permanent hydroperiods revealed a 26% increase in asexual female lifespan across seasons (23% decrease in the rate of aging) and a 56% increase in asexual fecundity, suggesting that maintenance in benign laboratory conditions leads to slower aging. The relative stasis of traits for sexual females implies an impact of reproductive physiology on evolvability. In addition we found a positive correlation between fecundity and lifespan, suggesting an absence of trade-offs in life history traits in the benign laboratory environment. PMID:24795527

Dynamics of asexual reproduction in flatworms

NASA Astrophysics Data System (ADS)

Schoetz, Eva-Maria; Talbot, Jared; Dunkel, Joern

2010-03-01

Planarians (flatworms) are one of the simplest bilaterally symmetric organisms and famous for their extraordinary regenerative capabilities. One can cut a worm in 100 pieces and after a few weeks one obtains 100 new worms that have reconstructed their entire body, including a central nervous system. This amazing regenerative capability is due to a population of stem cells distributed throughout the planarian body. These stem cells do not only allow the worms to heal without scarring after wounding, they also allow for asexual reproduction: Planarians can split themselves in two, and then regenerate the missing body parts within about a week. Naively, one would think that this kind of asexual reproduction could be captured by simple models that describe cell growth in bacteria or other lower organisms. However, we find that there is much more to the story by monitoring >15 generations of many individuals, as well as the long-term behavior (> 9 months) of worm populations under different environmental conditions, such as population density, temperature, and feeding frequency. Surprisingly, we observe that reproduction decreases with increasing food supply, opposite to the relationship between food and reproduction in other asexually reproducing organisms (e.g. bacteria, yeast), and causing obese worms. Finally, our data allows us to address the question of aging in an organism that is thought to be ``forever young''.

The frequency of sex in fungi

PubMed Central

James, Timothy Y.

2016-01-01

Fungi are a diverse group of organisms with a huge variation in reproductive strategy. While almost all species can reproduce sexually, many reproduce asexually most of the time. When sexual reproduction does occur, large variation exists in the amount of in- and out-breeding. While budding yeast is expected to outcross only once every 10 000 generations, other fungi are obligate outcrossers with well-mixed panmictic populations. In this review, we give an overview of the costs and benefits of sexual and asexual reproduction in fungi, and the mechanisms that evolved in fungi to reduce the costs of either mode. The proximate molecular mechanisms potentiating outcrossing and meiosis appear to be present in nearly all fungi, making them of little use for predicting outcrossing rates, but also suggesting the absence of true ancient asexual lineages. We review how population genetic methods can be used to estimate the frequency of sex in fungi and provide empirical data that support a mixed mode of reproduction in many species with rare to frequent sex in between rounds of mitotic reproduction. Finally, we highlight how these estimates might be affected by the fungus-specific mechanisms that evolved to reduce the costs of sexual and asexual reproduction. This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’. PMID:27619703

The frequency of sex in fungi.

PubMed

Nieuwenhuis, Bart P S; James, Timothy Y

2016-10-19

Fungi are a diverse group of organisms with a huge variation in reproductive strategy. While almost all species can reproduce sexually, many reproduce asexually most of the time. When sexual reproduction does occur, large variation exists in the amount of in- and out-breeding. While budding yeast is expected to outcross only once every 10 000 generations, other fungi are obligate outcrossers with well-mixed panmictic populations. In this review, we give an overview of the costs and benefits of sexual and asexual reproduction in fungi, and the mechanisms that evolved in fungi to reduce the costs of either mode. The proximate molecular mechanisms potentiating outcrossing and meiosis appear to be present in nearly all fungi, making them of little use for predicting outcrossing rates, but also suggesting the absence of true ancient asexual lineages. We review how population genetic methods can be used to estimate the frequency of sex in fungi and provide empirical data that support a mixed mode of reproduction in many species with rare to frequent sex in between rounds of mitotic reproduction. Finally, we highlight how these estimates might be affected by the fungus-specific mechanisms that evolved to reduce the costs of sexual and asexual reproduction.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'. © 2016 The Author(s).

Evidence of parasexual activity in "asexual amoebae" Cochliopodium spp. (Amoebozoa): extensive cellular and nuclear fusion.

PubMed

Tekle, Yonas I; Anderson, O Roger; Lecky, Ariel F

2014-09-01

The majority of microbial eukaryotes have long been considered asexual, though new evidence indicates sex, or sexual-like (parasexual) behaviors that deviate from the usual union of two gametes, among other variant aspects. Over a dozen amoebozoans are implicated to have sexual stages. However, the exact mechanism by which sex occurs in these lineages remains elusive. This is mainly due to the diverse quality and cryptic nature of their life cycle. In this study we present evidence of some previously unreported aspects of the life cycle of an amoeba, Cochliopodium, that undergoes unusual intraspecific interactions using light microscopy and immunocytochemistry. Similar to other amoebozoans, Cochliopodium, is considered asexual with no published reports of sex or parasexuality. We also investigated environmental conditions that govern the observed intraspecific interactions. Both light microscopic and immunocytochemistry evidence demonstrates Cochliopodium undergoes cellular fusion (plasmogamy) and nuclear fusion (karyogamy). Large plasmodia eventually undergo karyogamy and contain large fused, polyploid, nuclei. These are observed to fragment, subsequently, by karyotomy (nuclear fission) and cytoplasmic fission to yield uninucleated amoebae. This process could lead to a non-meiotic, parasexual exchange of chromosomes in Cochliopodium. These findings strongly suggest that Cochliopodium is involved in parasexual activity and should no longer be considered strictly asexual. Copyright © 2014 Elsevier GmbH. All rights reserved.

In Vitro Activities of Primaquine-Schizonticide Combinations on Asexual Blood Stages and Gametocytes of Plasmodium falciparum.

PubMed

Cabrera, Mynthia; Cui, Liwang

2015-12-01

Currently, the World Health Organization recommends addition of a 0.25-mg base/kg single dose of primaquine (PQ) to artemisinin combination therapies (ACTs) for Plasmodium falciparum malaria as a gametocytocidal agent for reducing transmission. Here, we investigated the potential interactions of PQ with the long-lasting components of the ACT drugs for eliminating the asexual blood stages and gametocytes of in vitro-cultured P. falciparum strains. Using the SYBR green I assay for asexual parasites and a flow cytometry-based assay for gametocytes, we determined the interactions of PQ with the schizonticides chloroquine, mefloquine, piperaquine, lumefantrine, and naphthoquine. With the sums of fractional inhibitory concentrations and isobolograms, we were able to determine mostly synergistic interactions for the various PQ and schizonticide combinations on the blood stages of P. falciparum laboratory strains. The synergism in inhibiting asexual stages and gametocytes was highly evident with PQ-naphthoquine, whereas synergism was moderate for the PQ-piperaquine, PQ-chloroquine, and PQ-mefloquine combinations. We have detected potentially antagonistic interactions between PQ and lumefantrine under certain drug combination ratios, suggesting that precautions might be needed when PQ is added as the gametocytocide to the artemether-lumefantrine ACT (Coartem). Copyright © 2015, American Society for Microbiology. All Rights Reserved.

The Pattern of Genetic Variability in Apomictic Clones of Taraxacum officinale Indicates the Alternation of Asexual and Sexual Histories of Apomicts

PubMed Central

Majeský, Ľuboš; Vašut, Radim J.; Kitner, Miloslav; Trávníček, Bohumil

2012-01-01

Dandelions (genus Taraxacum) comprise a group of sexual diploids and apomictic polyploids with a complicated reticular evolution. Apomixis (clonal reproduction through seeds) in this genus is considered to be obligate, and therefore represent a good model for studying the role of asexual reproduction in microevolutionary processes of apomictic genera. In our study, a total of 187 apomictic individuals composing a set of nine microspecies (sampled across wide geographic area in Europe) were genotyped for six microsatellite loci and for 162 amplified fragment length polymorphism (AFLP) markers. Our results indicated that significant genetic similarity existed within accessions with low numbers of genotypes. Genotypic variability was high among accessions but low within accessions. Clustering methods discriminated individuals into nine groups corresponding to their phenotypes. Furthermore, two groups of apomictic genotypes were observed, which suggests that they had different asexual histories. A matrix compatibility test suggests that most of the variability within accession groups was mutational in origin. However, the presence of recombination was also detected. The accumulation of mutations in asexual clones leads to the establishment of a network of clone mates. However, this study suggests that the clones primarily originated from the hybridisation between sexual and apomicts. PMID:22870257

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jordan, Jacob A.; Jubin, Robert Thomas

US regulations could require the removal of both iodine and tritium from the off-gas stream of a used nuclear fuel (UNF) reprocessing facility. Advanced tritium pretreatment is a pretreatment step that uses high concentrations of NOR2R in a gas stream to volatilize tritium and iodine from UNF prior to traditional dissolution. The gaseous effluent from this process would then require abatement to remove tritium and iodine, but high levels of NOR2R could have a detrimental effect on the ability of various solid sorbents to remove the volatile radionuclides. For tritium and iodine, the sorbents of interest are 3Å molecular sievemore » (3AMS) for tritium and reduced silver mordenite (AgP 0 PZ), silver-functionalized silica-aerogel (AgAerogel), and silver-nitrate-impregnated alumina (AgA) for iodine. Prior research has demonstrated that exposure to high concentrations of NOR2R can reduce the iodine loading capacity of AgP 0 PZ by > 90% when exposed for 1 week. Research in Japan has demonstrated that AgA is more robust to NOR2R exposure than AgZ. The testing described here was intended to assess the effects of high concentrations of NOR2R on the iodine capture capacity of AgA and the water adsorption capacity of 3AMS. To determine the effect of extended exposure of the sorbents to NOR2R, both 3AMS and AgA were aged in a 75% NOR2R environment prior to loading. The 3AMS samples were aged for 1, 4, and 5.5 weeks at 40°C. They were then loaded with water in a 10°C dew point stream (corresponding to a water concentration of ~12,000 ppmv) at 40°C. There was no significant change in the water adsorption capacity of the 3AMS upon exposure to 75% NOR2R. The AgA samples were aged for 1, 2, and 4 weeks at 150°C and were loaded with 50 ppmv IR2R at 150°C. The results show that the iodine capture capacity of AgA is reduced by exposure to high concentrations of NOR2R. The iodine capacity reductions were 16%, 36%, and 76% for 1, 2, and 4 week exposures, respectively. This is less of a capacity loss than that seen in similar testing with the AgP 0 PZ sorbent.« less

Illness perception in patients with androgenetic alopecia and alopecia areata in China.

PubMed

Yu, Nan-Lan; Tan, Huan; Song, Zhi-Qiang; Yang, Xi-Chuan

2016-07-01

The aim of the present study was to provide more information on the role of illness perception in patients with androgenetic alopecia (AGA) and those with alopecia areata (AA), and to further investigate the relationship of illness perception with psychological disorders and dermatological QoL. The study included 342 patients who were diagnosed with AGA (n=212) or AA (n=130) for the first time at our institution between October 2013 and December 2014. All patients were surveyed before clinical examination by several questionnaires including the Brief Illness Perception, Self-rating Depression Scale, Self-rating Anxiety Scale, and Dermatology Life Quality Index (DLQI). In the AGA patients, the illness perception and QoL were low, whereas the prevalence of clinical depression and anxiety was higher compared to the AA patients. Illness perception was associated with psychological distress and low QoL in both groups, and some illness perception dimensions were found to be significant predictors of the DLQI scores. Illness perception plays an important role in AGA and AA patients, and is associated with psychological distress and low QoL. The identification of critical components of illness perception in alopecia patients could help to understand alopecia specificities, to design consultations and interventions according to the perception, and to improve physical and mental outcomes as well as QoL in alopecia patients. Copyright © 2016 Elsevier Inc. All rights reserved.

A Single-Centre, Randomized, Double-Blind, Placebo-Controlled Clinical Trial to Investigate the Efficacy and Safety of Minoxidil Topical Foam in Frontotemporal and Vertex Androgenetic Alopecia in Men.

PubMed

Hillmann, Kathrin; Garcia Bartels, Natalie; Kottner, Jan; Stroux, Andrea; Canfield, Douglas; Blume-Peytavi, Ulrike

2015-01-01

5% minoxidil formulations twice daily are effective in treating vertex male androgenetic alopecia (AGA); however, efficacy and safety data in frontotemporal regions are lacking. To assess the efficacy of 5% minoxidil topical foam (5% MTF) in the frontotemporal region of male AGA patients after 24 weeks of treatment compared to placebo treatment and to the vertex region. Seventy males with moderate AGA applied 5% MTF or placebo foam (plaTF) twice daily for 24 weeks in frontotemporal and vertex regions. Target area non-vellus hair count (TAHC) was the primary end point. Frontotemporal and vertex TAHC and target area cumulative non-vellus hair width (TAHW) showed similar responses to 5% MTF with significant increases up to week 16 compared to baseline (p < 0.001). After 24 weeks of treatment, frontotemporal TAHW increased significantly in the 5% MTF group compared to the plaTF group (p = 0.017), while TAHC showed a similar non-significant increase from baseline in both regions. At 24 weeks, 5% MTF users rated a significant improvement in scalp coverage for the frontotemporal (p = 0.016) and vertex areas (p = 0.027). 5% MTF twice a day promotes hair density and width in both frontotemporal and vertex regions in men with moderate stages of AGA. © 2015 S. Karger AG, Basel.

Prostaglandin D2 Inhibits Hair Growth and Is Elevated in Bald Scalp of Men with Androgenetic Alopecia

PubMed Central

Garza, Luis A.; Liu, Yaping; Yang, Zaixin; Alagesan, Brinda; Lawson, John A.; Norberg, Scott M.; Loy, Dorothy E.; Zhao, Tailun; Blatt, Hanz B.; Stanton, David C.; Carrasco, Lee; Ahluwalia, Gurpreet; Fischer, Susan M.; FitzGerald, Garret A.; Cotsarelis, George

2012-01-01

Testosterone is necessary for the development of male pattern baldness, known as androgenetic alopecia (AGA); yet, the mechanisms for decreased hair growth in this disorder are unclear. We show that prostaglandin D2 synthase (PTGDS) is elevated at the mRNA and protein levels in bald scalp compared to haired scalp of men with AGA. The product of PTGDS enzyme activity, prostaglandin D2 (PGD2), is similarly elevated in bald scalp. During normal follicle cycling in mice, Ptgds and PGD2 levels increase immediately preceding the regression phase, suggesting an inhibitory effect on hair growth. We show that PGD2 inhibits hair growth in explanted human hair follicles and when applied topically to mice. Hair growth inhibition requires the PGD2 receptor G protein (heterotrimeric guanine nucleotide)–coupled receptor 44 (GPR44), but not the PGD2 receptor 1 (PTGDR). Furthermore, we find that a transgenic mouse, K14-Ptgs2, which targets prostaglandin-endoperoxide synthase 2 expression to the skin, demonstrates elevated levels of PGD2 in the skin and develops alopecia, follicular miniaturization, and sebaceous gland hyperplasia, which are all hallmarks of human AGA. These results define PGD2 as an inhibitor of hair growth in AGA and suggest the PGD2-GPR44 pathway as a potential target for treatment. PMID:22440736

Blockade of Androgen Markers Using a Novel Betasitosterol, Thioctic Acid and Carnitine-containing Compound in Prostate and Hair Follicle Cell-based Assays.

PubMed

Chen, Li; Wang, Jiaolong; Mouser, Glen; Li, Yan Chun; Marcovici, Geno

2016-06-01

Androgenetic alopecia (AGA) affects approximately 70% of men and 40% of women in an age-dependent manner and is partially mediated by androgen hormones. Benign prostatic hyperplasia (BPH) similarly affects 50% of the male population, rising by 10% each decade. Finasteride inhibits 5-alpha reductase (5AR) and is used to treat both disorders, despite offering limited clinical benefits accompanied by significant adverse side effects. Building on our previous work demonstrating the efficacy of naturally derived 5AR inhibitors (such as stigmasterol and beta sitosterol), we hypothesize that targeting 5AR as well as inflammatory pathways may yield improved efficacy in AGA and BPH. Here we address these dual pathomechanisms by examining the potency of a novel composition using in vitro assays of representative cell lines for AGA (hair follicle dermal papilla cells) and BPH (LNCaP prostate cells), respectively. Exposure of cells to the novel test composition down-regulated mRNA expression profiles characteristic of both disease processes, which outperformed finasteride. Changes in mRNA expression were corroborated at the protein level as assessed by western blotting. These studies provide proof of concept that novel, naturally derived compositions simultaneously targeting 5AR and inflammatory mediators may represent a rational approach to treating AGA and BPH. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Enzymatic liquefaction of agarose above the sol-gel transition temperature using a thermostable endo-type β-agarase, Aga16B.

PubMed

Kim, Jung Hyun; Yun, Eun Ju; Seo, Nari; Yu, Sora; Kim, Dong Hyun; Cho, Kyung Mun; An, Hyun Joo; Kim, Jae-Han; Choi, In-Geol; Kim, Kyoung Heon

2017-02-01

The main carbohydrate of red macroalgae is agarose, a heterogeneous polysaccharide composed of D-galactose and 3,6-anhydro-L-galactose. When saccharifying agarose by enzymes, the unique physical properties of agarose, namely the sol-gel transition and the near-insolubility of agarose in water, limit the accessibility of agarose to the enzymes. Due to the lower accessibility of agarose to enzymes in the gel state than to the sol state, it is important to prevent the sol-gel transition by performing the enzymatic liquefaction of agarose at a temperature higher than the sol-gel transition temperature of agarose. In this study, a thermostable endo-type β-agarase, Aga16B, originating from Saccharophagus degradans 2-40 T , was characterized and introduced in the liquefaction process. Aga16B was thermostable up to 50 °C and depolymerized agarose mainly into neoagarooligosaccharides with degrees of polymerization 4 and 6. Aga16B was applied to enzymatic liquefaction of agarose at 45 °C, which was above the sol-gel transition temperature of 1 % (w/v) agarose (∼35 °C) when cooling agarose. This is the first systematic demonstration of enzymatic liquefaction of agarose, enabled by determining the sol-gel temperature of agarose under specific conditions and by characterizing the thermostability of an endo-type β-agarase.

Foetal growth restriction is associated with poor reading and spelling skills at eight years to 10 years of age.

PubMed

Partanen, Lea; Korkalainen, Noora; Mäkikallio, Kaarin; Olsén, Päivi; Laukkanen-Nevala, Päivi; Yliherva, Anneli

2018-01-01

Foetal growth restriction (FGR) is associated with communication problems, which might lead to poor literacy skills. The reading and spelling skills of eight- to 10-year-old FGR children born at 24-40 gestational weeks were compared with those of their gestational age-matched, appropriately grown (AGA) peers. A prospectively collected cohort of 37 FGR and 31 AGA children was recruited prenatally at a Finnish tertiary care centre during 1998-2001. The children's reading and spelling skills were assessed using standardised tests for Finnish-speaking second and third graders. Significantly more children performed below the 10th percentile normal values for reading and spelling skills in the FGR group than in the AGA group. At nine years of age, the FGR children had significantly poorer performance in word reading skills and reading fluency, reading accuracy and reading comprehension than the AGA controls. No between-group differences were detected at eight years of age. FGR is associated with poor performance in reading and spelling skills. A third of the FGR children performed below the 10th percentile normal values at nine years of age. These results indicate a need to continuously evaluate linguistic and literacy skills as FGR children age to ensure optimal support. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

Does Haplodiploidy Purge Inbreeding Depression in Rotifer Populations?

PubMed Central

Tortajada, Ana M.; Carmona, María José; Serra, Manuel

2009-01-01

Background Inbreeding depression is an important evolutionary factor, particularly when new habitats are colonized by few individuals. Then, inbreeding depression by drift could favour the establishment of later immigrants because their hybrid offspring would enjoy higher fitness. Rotifers are the only major zooplanktonic group where information on inbreeding depression is still critically scarce, despite the fact that in cyclical parthenogenetic rotifers males are haploid and could purge deleterious recessive alleles, thereby decreasing inbreeding depression. Methodology/Principal Findings We studied the effects of inbreeding in two populations of the cyclical parthenogenetic rotifer Brachionus plicatilis. For each population, we compared both the parental fertilization proportion and F1 fitness components from intraclonal (selfed) and interclonal (outcrossed) crosses. The parental fertilization proportion was similar for both types of crosses, suggesting that there is no mechanism to avoid selfing. In the F1 generation of both populations, we found evidence of inbreeding depression for the fitness components associated with asexual reproduction; whereas inbreeding depression was only found for one of the two sexual reproduction fitness components measured. Conclusions/Significance Our results show that rotifers, like other major zooplanktonic groups, can be affected by inbreeding depression in different stages of their life cycle. These results suggest that haplodiploidy does not purge efficiently deleterious recessive alleles. The inbreeding depression detected here has important implications when a rotifer population is founded and intraclonal crossing is likely to occur. Thus, during the foundation of new populations inbreeding depression may provide opportunities for new immigrants, increasing gene flow between populations, and affecting genetic differentiation. PMID:19997616

Ploidy, sex and crossing over in an evolutionary aging model

NASA Astrophysics Data System (ADS)

Lobo, Matheus P.; Onody, Roberto N.

2006-02-01

Nowadays, many forms of reproduction coexist in nature: Asexual, sexual, apomictic and meiotic parthenogenesis, hermaphroditism and parasex. The mechanisms of their evolution and what made them successful reproductive alternatives are very challenging and debated questions. Here, using a simple evolutionary aging model, we give a possible scenario. By studying the performance of populations where individuals may have diverse characteristics-different ploidies, sex with or without crossing over, as well as the absence of sex-we find an evolution sequence that may explain why there are actually two major or leading groups: Sexual and asexual. We also investigate the dependence of these characteristics on different conditions of fertility and deleterious mutations. Finally, if the primeval organisms on Earth were, in fact, asexual individuals we conjecture that the sexual form of reproduction could have more easily been set and found its niche during a period of low-intensity mutations.

Transposable elements in sexual and ancient asexual taxa

PubMed Central

Arkhipova, Irina; Meselson, Matthew

2000-01-01

Sexual reproduction allows deleterious transposable elements to proliferate in populations, whereas the loss of sex, by preventing their spread, has been predicted eventually to result in a population free of such elements [Hickey, D. A. (1982) Genetics 101, 519–531]. We tested this expectation by screening representatives of a majority of animal phyla for LINE-like and gypsy-like reverse transcriptases and mariner/Tc1-like transposases. All species tested positive for reverse transcriptases except rotifers of the class Bdelloidea, the largest eukaryotic taxon in which males, hermaphrodites, and meiosis are unknown and for which ancient asexuality is supported by molecular genetic evidence. Mariner-like transposases are distributed sporadically among species and are present in bdelloid rotifers. The remarkable lack of LINE-like and gypsy-like retrotransposons in bdelloids and their ubiquitous presence in other taxa support the view that eukaryotic retrotransposons are sexually transmitted nuclear parasites and that bdelloid rotifers evolved asexually. PMID:11121049

Growth restriction and gender influence cerebral oxygenation in preterm neonates.

PubMed

Cohen, Emily; Baerts, Willem; Alderliesten, Thomas; Derks, Jan; Lemmers, Petra; van Bel, Frank

2016-03-01

To investigate the effect of fetal growth restriction and gender on cerebral oxygenation in preterm neonates during the first 3 days of life. Case-control study. Neonatal Intensive Care Unit of the Wilhelmina Children's Hospital, The Netherlands. 68 (41 males) small for gestational age (SGA) (birth weight <10th percentile) and 136 (82 males) appropriate for gestational age (AGA) (birth weight 20th-80th percentile) neonates, matched for gender, gestational age, ventilatory and blood pressure support. Regional cerebral oxygen saturation (rScO2) and cerebral fractional tissue oxygen extraction (cFTOE) as measured by near-infrared spectroscopy throughout the first 72 h of life were compared between SGA and AGA neonates. The effect of gender was also explored within these comparisons. SGA neonates demonstrated higher rScO2 (71% SEM 0.2 vs 68% SEM 0.2) and lower cFTOE (0.25 SEM 0.002 vs 0.29 SEM 0.002) than AGA neonates. There was an independent effect of gender on rScO2 and cFTOE, resulting in the finding that SGA males displayed highest rScO2 and lowest cFTOE (73% SEM 0.3 respectively 0.24 SEM 0.003). AGA males and SGA females showed comparable rScO2 (69% SEM 0.2 vs 69% SEM 0.4) and cFTOE (0.28 SEM 0.002 vs 0.28 SEM 0.004). AGA females showed lowest rScO2 and highest cFTOE (66% SEM 0.2 respectively 0.30 SEM 0.002). Growth restriction and gender influence cerebral oxygenation and oxygen extraction in preterm neonates throughout the first 3 days of life. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Comparison of Fetal and Neonatal Growth Curves in Detecting Growth Restriction

PubMed Central

Marconi, Anna Maria; Ronzoni, Stefania; Bozzetti, Patrizia; Vailati, Simona; Morabito, Alberto; Battaglia, Frederick C

2009-01-01

Objective To evaluate the outcome of intrauterine growth restriction (IUGR) infants with abnormal pulsatility index of the umbilical artery according to the neonatal birth weight/gestational age standards and the intrauterine growth charts. Methods We analyzed 53 pregnancies with severe IUGR classified as Group 2 (22 IUGR: abnormal pulsatility index and normal fetal heart rate) and Group 3 (31 IUGR: abnormal pulsatility index and fetal heart rate). Neonatal birth weight/gestational age distribution, body size measurements, maternal characteristics and obstetric outcome, and neonatal major and minor morbidity and mortality were compared with those obtained in 79 singleton pregnancies with normal fetal growth and pulsatility index, matched for gestational age [appropriate for gestational age (AGA) group]. Differences were analyzed with the χ2 test and the Student’s t test. Differences between means corrected for gestational age in the different groups were assessed by analysis of covariance test. A P value <0.05 was considered significant. Results At delivery, utilizing the neonatal standards, 25/53 (47%) IUGR showed a birthweight above the 10th percentile (IUGRAGA) whereas in 28, birthweight was below the 10th percentile (IUGRSGA). All body size measurements were significantly higher in AGA than in IUGRAGA and IUGRSGA. Forty-nine out of 79 (62%) AGA and 49/53 (92%) IUGR were admitted in the neonatal intensive care unit (p<0.001). One out of 79 (1%) AGA and 6/53 (11%) IUGR newborns died within 28 days (p<0.02). Major and minor morbidity was not different. Conclusion This study shows that neonatal outcome is similar in IUGR of the same clinical severity, whether or not they could be defined AGA or SGA according to the neonatal standards. Neonatal curves are misleading in detecting low birthweight infants and should be utilized only when obstetrical data are unavailable. PMID:19037030

Silver Complexes of Dihalogen Molecules.

PubMed

Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

2016-08-01

The perfluorohexane-soluble and donor-free silver compound Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) prepared using a facile novel route has unprecedented capabilities to form unusual and weakly bound complexes. Here, we report on the three dihalogen-silver complexes Ag(Cl2 )A, Ag(Br2 )A, and Ag(I2 )A derived from the soluble silver compound Ag(A) (characterized by single-crystal/powder XRD, Raman spectra, and quantum-mechanical calculations). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Risk factors for Plasmodium falciparum and Plasmodium vivax gametocyte carriage in Papua New Guinean children with uncomplicated malaria.

PubMed

Karl, Stephan; Laman, Moses; Moore, Brioni R; Benjamin, John M; Salib, Mary; Lorry, Lina; Maripal, Samuel; Siba, Peter; Robinson, Leanne J; Mueller, Ivo; Davis, Timothy M E

2016-08-01

There are limited data on gametocytaemia risk factors before/after treatment with artemisinin combination therapy in children from areas with transmission of multiple Plasmodium species. We utilised data from a randomised trial comparing artemether-lumefantrine (AL) and artemisinin-naphthoquine (AN) in 230 Papua New Guinean children aged 0.5-5 years with uncomplicated malaria in whom determinants of gametocytaemia by light microscopy were assessed at baseline using logistic regression and during follow-up using multilevel mixed effects modelling. Seventy-four (32%) and 18 (8%) children presented with P. falciparum and P. vivax gametocytaemia, respectively. Baseline P. falciparum gametocytaemia was associated with Hackett spleen grade 1 (odds ratio (95% CI) 4.01 (1.60-10.05) vs grade 0; P<0.001) and haemoglobin (0.95 (0.92-0.97) per 1g/L increase; P<0.001), and P. falciparum asexual parasitaemia in slide-positive cases (0.36 (0.19-0.68) for a 10-fold increase; P=0.002). Baseline P. vivax gametocytaemia was associated with Hackett grade 2 (12.66 (1.31-122.56); P=0.028), mixed P. falciparum/vivax infection (0.16 (0.03-1.00); P=0.050), P. vivax asexual parasitaemia (5.68 (0.98-33.04); P=0.053) and haemoglobin (0.94 (0.88-1.00); P=0.056). For post-treatment P. falciparum gametocytaemia, independent predictors were AN vs AL treatment (4.09 (1.43-11.65)), haemoglobin (0.95 (0.93-0.97)), presence/absence of P. falciparum asexual forms (3.40 (1.66-0.68)) and day post-treatment (0.086 (0.82-0.90)) (P<0.001). Post-treatment P. vivax gametocytaemia was predicted by presence of P. vivax asexual forms (596 (12-28,433); P<0.001). Consistent with slow P. falciparum gametocyte maturation, low haemoglobin, low asexual parasite density and higher spleen grading, markers of increased prior infection exposure/immunity, were strong associates of pre-treatment gametocyte positivity. The persistent inverse association between P. falciparum gametocytaemia and haemoglobin during follow-up suggests an important role for bone marrow modulation of gametocytogenesis. In P. vivax infections, baseline and post-treatment gametocyte carriage was positively related to the acute parasite burden, reflecting the close association between the development of asexual and sexual forms. Copyright © 2016 Elsevier B.V. All rights reserved.

What does the geography of parthenogenesis teach us about sex?

PubMed

Tilquin, Anaïs; Kokko, Hanna

2016-10-19

Theory predicts that sexual reproduction is difficult to maintain if asexuality is an option, yet sex is very common. To understand why, it is important to pay attention to repeatably occurring conditions that favour transitions to, or persistence of, asexuality. Geographic parthenogenesis is a term that has been applied to describe a large variety of patterns where sexual and related asexual forms differ in their geographic distribution. Often asexuality is stated to occur in a habitat that is, in some sense, marginal, but the interpretation differs across studies: parthenogens might not only predominate near the margin of the sexuals' distribution, but might also extend far beyond the sexual range; they may be disproportionately found in newly colonizable areas (e.g. areas previously glaciated), or in habitats where abiotic selection pressures are relatively stronger than biotic ones (e.g. cold, dry). Here, we review the various patterns proposed in the literature, the hypotheses put forward to explain them, and the assumptions they rely on. Surprisingly, few mathematical models consider geographic parthenogenesis as their focal question, but all models for the evolution of sex could be evaluated in this framework if the (often ecological) causal factors vary predictably with geography. We also recommend broadening the taxa studied beyond the traditional favourites.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'. © 2016 The Author(s).

Comparative Transcriptomic and Proteomic Analyses Reveal a FluG-Mediated Signaling Pathway Relating to Asexual Sporulation of Antrodia camphorata.

PubMed

Li, Hua-Xiang; Lu, Zhen-Ming; Zhu, Qing; Gong, Jin-Song; Geng, Yan; Shi, Jin-Song; Xu, Zheng-Hong; Ma, Yan-He

2017-09-01

Medicinal mushroom Antrodia camphorata sporulate large numbers of arthroconidia in submerged fermentation, which is rarely reported in basidiomycetous fungi. Nevertheless, the molecular mechanisms underlying this asexual sporulation (conidiation) remain unclear. Here, we used comparative transcriptomic and proteomic approaches to elucidate possible signaling pathway relating to the asexual sporulation of A. camphorata. First, 104 differentially expressed proteins and 2586 differential cDNA sequences during the culture process of A. camphorata were identified by 2DE and RNA-seq, respectively. By applying bioinformatics analysis, a total of 67 genes which might play roles in the sporulation were obtained, and 18 of these genes, including fluG, sfgA, SfaD, flbA, flbB, flbC, flbD, nsdD, brlA, abaA, wetA, ganB, fadA, PkaA, veA, velB, vosA, and stuA might be involved in a potential FluG-mediated signaling pathway. Furthermore, the mRNA expression levels of the 18 genes in the proposed FluG-mediated signaling pathway were analyzed by quantitative real-time PCR. In summary, our study helps elucidate the molecular mechanisms underlying the asexual sporulation of A. camphorata, and provides also useful transcripts and proteome for further bioinformatics study of this valuable medicinal mushroom. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aspergillus, its sexual states and the new International Code of Nomenclature.

PubMed

Pitt, John I; Taylor, John W

2014-01-01

The newly adopted International Code of Nomenclature for algae, fungi and plants (ICN) demands that dimorphic fungi, in particular those with both sexual and asexual names, now bear a single name. Although priority is no longer associated with the mode of reproduction, the ICN requires justification for choosing an asexual name over an existing sexual one. The phylogenetic approach that made dual nomenclature for fungi obsolete can be used to help choose names for large groups of fungi that are best known by asexual names. Here we apply this approach to one of the largest and most diverse asexual genera, the genus Aspergillus. We find that existing sexual names may be given to well supported clades of fungi with distinct phenotypes, which include sexual morphology as well as physiological attributes associated with xerophily, thermophily and mycotoxin production. One group of species important to food production and food safety, Aspergillus subgen. Circumdati, lacks a well supported clade; here we propose that the name Aspergillus be retained for this group. Recognizing that nomenclature has economic and social implications, particularly for old, important genera, we discuss the consequences of various scenarios to implement the new "one name for one fungus" article in the ICN, showing that our approach requires the fewest appeals to the ICN while retaining the name Aspergillus for many of the most economically and socially important species. © 2014 by The Mycological Society of America.

Robust inducible Cre recombinase activity in the human malaria parasite Plasmodium falciparum enables efficient gene deletion within a single asexual erythrocytic growth cycle.

PubMed

Collins, Christine R; Das, Sujaan; Wong, Eleanor H; Andenmatten, Nicole; Stallmach, Robert; Hackett, Fiona; Herman, Jean-Paul; Müller, Sylke; Meissner, Markus; Blackman, Michael J

2013-05-01

Asexual blood stages of the malaria parasite, which cause all the pathology associated with malaria, can readily be genetically modified by homologous recombination, enabling the functional study of parasite genes that are not essential in this part of the life cycle. However, no widely applicable method for conditional mutagenesis of essential asexual blood-stage malarial genes is available, hindering their functional analysis. We report the application of the DiCre conditional recombinase system to Plasmodium falciparum, the causative agent of the most dangerous form of malaria. We show that DiCre can be used to obtain rapid, highly regulated site-specific recombination in P. falciparum, capable of excising loxP-flanked sequences from a genomic locus with close to 100% efficiency within the time-span of a single erythrocytic growth cycle. DiCre-mediated deletion of the SERA5 3' UTR failed to reduce expression of the gene due to the existence of alternative cryptic polyadenylation sites within the modified locus. However, we successfully used the system to recycle the most widely used drug resistance marker for P. falciparum, human dihydrofolate reductase, in the process producing constitutively DiCre-expressing P. falciparum clones that have broad utility for the functional analysis of essential asexual blood-stage parasite genes. © 2013 John Wiley & Sons Ltd.

What does the geography of parthenogenesis teach us about sex?

PubMed Central

Kokko, Hanna

2016-01-01

Theory predicts that sexual reproduction is difficult to maintain if asexuality is an option, yet sex is very common. To understand why, it is important to pay attention to repeatably occurring conditions that favour transitions to, or persistence of, asexuality. Geographic parthenogenesis is a term that has been applied to describe a large variety of patterns where sexual and related asexual forms differ in their geographic distribution. Often asexuality is stated to occur in a habitat that is, in some sense, marginal, but the interpretation differs across studies: parthenogens might not only predominate near the margin of the sexuals' distribution, but might also extend far beyond the sexual range; they may be disproportionately found in newly colonizable areas (e.g. areas previously glaciated), or in habitats where abiotic selection pressures are relatively stronger than biotic ones (e.g. cold, dry). Here, we review the various patterns proposed in the literature, the hypotheses put forward to explain them, and the assumptions they rely on. Surprisingly, few mathematical models consider geographic parthenogenesis as their focal question, but all models for the evolution of sex could be evaluated in this framework if the (often ecological) causal factors vary predictably with geography. We also recommend broadening the taxa studied beyond the traditional favourites. This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’. PMID:27619701

Associations Between Helminth Infections, Plasmodium falciparum Parasite Carriage and Antibody Responses to Sexual and Asexual Stage Malarial Antigens.

PubMed

Ateba-Ngoa, Ulysse; Jones, Sophie; Zinsou, Jeannot Fréjus; Honkpehedji, Josiane; Adegnika, Ayola Akim; Agobe, Jean-Claude Dejon; Massinga-Loembe, Marguerite; Mordmüller, Benjamin; Bousema, Teun; Yazdanbakhsh, Maria

2016-08-03

Infections with helminths and Plasmodium spp. overlap in their geographical distribution. It has been postulated that helminth infections may influence malarial transmission by altering Plasmodium falciparum gametocytogenesis. This cross-sectional study assessed the effect of helminth infections on P. falciparum gametocyte carriage and on humoral immune responses to sexual stage antigens in Gabon. Schistosoma haematobium and filarial infections as well as P. falciparum asexual forms and gametocyte carriage were determined. The antibody responses measured were to sexual (Pfs230, Pfs48/45) and asexual P. falciparum antigens (AMA1, MSP1, and GLURP). A total of 287 subjects were included. The prevalence of microscopically detectable P. falciparum asexual parasites was higher in S. haematobium-infected subjects in comparison to their uninfected counterparts (47% versus 26%, P = 0.003), but this was not different when filarial infections were considered. Plasmodium falciparum gametocyte carriage was similar between Schistosoma- or filaria-infected and uninfected subjects. We observed a significant decrease of Pfs48/45 immunoglobulin G titer in S. haematobium-infected subjects (P = 0.037), whereas no difference was seen for Pfs230 antibody titer, nor for antibodies to AMA1, MSP1, or GLURP. Our findings suggest an effect of S. haematobium on antibody responses to some P. falciparum gametocyte antigens that may have consequences for transmission-blocking immunity. © The American Society of Tropical Medicine and Hygiene.

Low-level laser/light therapy for androgenetic alopecia.

PubMed

Gupta, Aditya K; Lyons, Danika C A; Abramovits, William

2014-01-01

Androgenetic alopecia (AGA) is a persistent and pervasive condition that affects men worldwide. Some common treatment options for AGA include hair prosthetics, oral and topical medications, and surgical hair restoration (SHR). Pharmaceutical and SHR treatments are associated with limitations including adverse side effects and significant financial burden. Low-level laser or light (LLL) devices offer alternative treatment options that are not typically associated with adverse side effects or significant costs. There are clinic- and home-based LLL devices. One home-based laser comb device has set a standard for others; however, this device requires time devoted to carefully moving the comb through the hair to allow laser penetration to the scalp. A novel helmet-like LLL device for hair growth has proven effective in preliminary trials and allows for hands-free use. Regardless, there are few clinical trials that have been conducted regarding LLL devices for AGA and results are mixed. Further research is required to establish the true efficacy of these devices for hair growth in comparison to existing alternative therapies.

Novel enzymatic assay predicts minoxidil response in the treatment of androgenetic alopecia.

PubMed

Goren, Andy; Castano, Juan Antonio; McCoy, John; Bermudez, Fernando; Lotti, Torello

2014-01-01

Topical minoxidil is the most common drug used for the treatment of androgenetic alopecia (AGA) in men and women. Although topical minoxidil exhibits a good safety profile, the efficacy in the overall population remains relatively low at 30-40%. To observe significant improvement in hair growth, minoxidil is typically used daily for a period of at least 3-4 months. Due to the significant time commitment and low response rate, a biomarker for predicting patient response prior to therapy would be advantageous. Minoxidil is converted in the scalp to its active form, minoxidil sulfate, by the sulfotransferase enzyme SULT1A1. We hypothesized that SULT1A1 enzyme activity in the hair follicle correlates with minoxidil response for the treatment of AGA. Our preliminary retrospective study of a SULT1A1 activity assay demonstrates 95% sensitivity and 73% specificity in predicting minoxidil treatment response for AGA. A larger prospective study is now under way to further validate this novel assay. © 2013 Wiley Periodicals, Inc.

Lysine-Tryptophan-Crosslinked Peptides Produced by Radical SAM Enzymes in Pathogenic Streptococci.

PubMed

Schramma, Kelsey R; Seyedsayamdost, Mohammad R

2017-04-21

Macrocycles represent a common structural framework in many naturally occurring peptides. Several strategies exist for macrocyclization, and the enzymes that incorporate them are of great interest, as they enhance our repertoire for creating complex molecules. We recently discovered a new peptide cyclization reaction involving a crosslink between the side chains of lysine and tryptophan that is installed by a radical SAM enzyme. Herein, we characterize relatives of this metalloenzyme from the pathogens Streptococcus agalactiae and Streptococcus suis. Our results show that the corresponding enzymes, which we call AgaB and SuiB, contain multiple [4Fe-4S] clusters and catalyze Lys-Trp crosslink formation in their respective substrates. Subsequent high-resolution-MS and 2D-NMR analyses located the site of macrocyclization. Moreover, we report that AgaB can accept modified substrates containing natural or unnatural amino acids. Aside from providing insights into the mechanism of this unusual modification, the substrate promiscuity of AgaB may be exploited to create diverse macrocyclic peptides.

The distribution of intra-genomically variable dinoflagellate symbionts at Lord Howe Island, Australia

NASA Astrophysics Data System (ADS)

Wilkinson, Shaun P.; Pontasch, Stefanie; Fisher, Paul L.; Davy, Simon K.

2016-06-01

The symbiotic dinoflagellates of corals and other marine invertebrates ( Symbiodinium) are essential to the development of shallow-water coral reefs. This genus contains considerable genetic diversity and a corresponding range of physiological and ecological traits. Most genetic variation arises through the accumulation of somatic mutations that arise during asexual reproduction. Yet growing evidence suggests that occasional sexual reproductive events also occur within, and perhaps between, Symbiodinium lineages, further contributing to the pool of genetic variation available for evolutionary adaptation. Intra-genomic variation can therefore arise from both sexual and asexual reproductive processes, making it difficult to discern its underlying causes and consequences. We used quantitative PCR targeting the ITS2 locus to estimate proportions of genetically homogeneous symbionts and intra-genomically variable Symbiodinium (IGV Symbiodinium) in the reef-building coral Pocillopora damicornis at Lord Howe Island, Australia. We then sampled colonies through time and at a variety of spatial scales to find out whether the distribution of these symbionts followed patterns consistent with niche partitioning. Estimated ratios of homogeneous to IGV Symbiodinium varied between colonies within sites (metres to tens of metres) and between sites separated by hundreds to thousands of metres, but remained stable within colonies through time. Symbiont ratios followed a temperature gradient, with the local thermal maximum emerging as a negative predictor for the estimated proportional abundance of IGV Symbiodinium. While this pattern may result from fine-scale spatial population structure, it is consistent with an increased susceptibility to thermal stress, suggesting that the evolutionary processes that generate IGV (such as inter-lineage recombination and the accumulation of somatic mutations at the ITS2 locus) may have important implications for the fitness of the symbiont and that of the coral host.

Juvenile honest food solicitation and parental investment as a life history strategy: A kin demographic selection model.

PubMed

Garay, József; Csiszár, Villő; Móri, Tamás F; Szilágyi, András; Varga, Zoltán; Számadó, Szabolcs

2018-01-01

Parent-offspring communication remains an unresolved challenge for biologist. The difficulty of the challenge comes from the fact that it is a multifaceted problem with connections to life-history evolution, parent-offspring conflict, kin selection and signalling. Previous efforts mainly focused on modelling resource allocation at the expense of the dynamic interaction during a reproductive season. Here we present a two-stage model of begging where the first stage models the interaction between nestlings and parents within a nest and the second stage models the life-history trade-offs. We show in an asexual population that honest begging results in decreased variance of collected food between siblings, which leads to mean number of surviving offspring. Thus, honest begging can be seen as a special bet-hedging against informational uncertainty, which not just decreases the variance of fitness but also increases the arithmetic mean.

Juvenile honest food solicitation and parental investment as a life history strategy: A kin demographic selection model

PubMed Central

Szilágyi, András; Varga, Zoltán

2018-01-01

Parent-offspring communication remains an unresolved challenge for biologist. The difficulty of the challenge comes from the fact that it is a multifaceted problem with connections to life-history evolution, parent-offspring conflict, kin selection and signalling. Previous efforts mainly focused on modelling resource allocation at the expense of the dynamic interaction during a reproductive season. Here we present a two-stage model of begging where the first stage models the interaction between nestlings and parents within a nest and the second stage models the life-history trade-offs. We show in an asexual population that honest begging results in decreased variance of collected food between siblings, which leads to mean number of surviving offspring. Thus, honest begging can be seen as a special bet-hedging against informational uncertainty, which not just decreases the variance of fitness but also increases the arithmetic mean. PMID:29494630

The evolutionary theory of asymmetry by V. Geodakyan

NASA Astrophysics Data System (ADS)

Geodakyan, Sergey V.

2015-08-01

For more than 150 years, all biological theories, including those of C. Darwin and Mendel, were based on the idea of synchronous evolution. They fit for unitary monomodal systems (asexual, symmetrical) but do not work for binary (dioecious, asymmetrical) ones. Examples of such binary conjugated differentiations are two sexes, DNA-proteins, autosomes-sex chromosomes, right and left brain hemispheres, and hands. For their understanding, "asynchronous" theories are needed. Such theories were proposed by Russian theoretical biologist Vigen A. Geodakyan for sexual, brain and body, and chromosomal differentiations. All theories are interconnected and are based on the principle of conjugated subsystems. This article covers the basic tenets of the evolutionary theory of asymmetry and answers the following questions: What benefits does lateralization provide? What logic, what principle is it based on? Why do brain hemispheres control the opposite sides of the body? Why laterality is closely related to sex? What are the biological prerequisites of terrorism?

Strategies for the Evolution of Sex

NASA Astrophysics Data System (ADS)

Erzan, Ayse

2002-03-01

Using a bit-string model of evolution we find a successful route to diploidy and sex in simple organisms, for a step-like fitness function. Assuming that an excess of deleterious mutations triggers the conversion of haploids to diploidy and sex, we find that only one pair of sexual organisms can take over a finite population, if they engage in sexual reproduction under unfavorable conditions, and otherwise perform mitosis. Then, a haploid-diploid (HD) cycle is established, with an abbreviated haploid phase, as in present day sexual reproduction. If crossover is allowed during meiosis, HD cycles of arbitrary duration can be maintained. We find that the sexual population has a higher mortality rate than asexual diploids, but also a relaxation rate that is an order of magnitude higher. As a result, sexuals have a higher adaptability and lower mutational load on the average, since they can select out the undesirable genes much faster.

Production of a Highly Protease-Resistant Fungal α-Galactosidase in Transgenic Maize Seeds for Simplified Feed Processing

PubMed Central

Zhou, Xiaojin; Zhang, Wei; Xu, Xiaolu; Chen, Rumei; Meng, Qingchang; Yuan, Jianhua; Yang, Peilong; Yao, Bin

2015-01-01

Raffinose-family oligosaccharide (RFO) in soybeans is one of the major anti-nutritional factors for poultry and livestocks. α-Galactosidase is commonly supplemented into the animal feed to hydrolyze α-1,6-galactosidic bonds on the RFOs. To simplify the feed processing, a protease-resistant α-galactosidase encoding gene from Gibberella sp. strain F75, aga-F75, was modified by codon optimization and heterologously expressed in the embryos of transgentic maize driven by the embryo-specific promoter ZM-leg1A. The progenies were produced by backcrossing with the commercial inbred variety Zheng58. PCR, southern blot and western blot analysis confirmed the stable integration and tissue specific expression of the modified gene, aga-F75m, in seeds over four generations. The expression level of Aga-F75M reached up to 10,000 units per kilogram of maize seeds. In comparison with its counterpart produced in Pichia pastoris strain GS115, maize seed-derived Aga-F75M showed a lower temperature optimum (50°C) and lower stability over alkaline pH range, but better thermal stability at 60°C to 70°C and resistance to feed pelleting inactivation (80°C). This is the first report of producing α-galactosidase in transgenic plant. The study offers an effective and economic approach for direct utilization of α-galactosidase-producing maize without any purification or supplementation procedures in the feed processing. PMID:26053048

beta subunits influence the biophysical and pharmacological differences between P- and Q-type calcium currents expressed in a mammalian cell line.

PubMed

Moreno, H; Rudy, B; Llinás, R

1997-12-09

Human epithelial kidney cells (HEK) were prepared to coexpress alpha1A, alpha2delta with different beta calcium channel subunits and green fluorescence protein. To compare the calcium currents observed in these cells with the native neuronal currents, electrophysiological and pharmacological tools were used conjointly. Whole-cell current recordings of human epithelial kidney alpha1A-transfected cells showed small inactivating currents in 80 mM Ba2+ that were relatively insensitive to calcium blockers. Coexpression of alpha1A, betaIb, and alpha2delta produced a robust inactivating current detected in 10 mM Ba2+, reversibly blockable with low concentration of omega-agatoxin IVA (omega-Aga IVA) or synthetic funnel-web spider toxin (sFTX). Barium currents were also supported by alpha1A, beta2a, alpha2delta subunits, which demonstrated the slowest inactivation and were relatively insensitive to omega-Aga IVA and sFTX. Coexpression of beta3 with the same combination as above produced inactivating currents also insensitive to low concentration of omega-Aga IVA and sFTX. These data indicate that the combination alpha1A, betaIb, alpha2delta best resembles P-type channels given the rate of inactivation and the high sensitivity to omega-Aga IVA and sFTX. More importantly, the specificity of the channel blocker is highly influenced by the beta subunit associated with the alpha1A subunit.

Production of a Highly Protease-Resistant Fungal α-Galactosidase in Transgenic Maize Seeds for Simplified Feed Processing.

PubMed

Yang, Wenxia; Zhang, Yuhong; Zhou, Xiaojin; Zhang, Wei; Xu, Xiaolu; Chen, Rumei; Meng, Qingchang; Yuan, Jianhua; Yang, Peilong; Yao, Bin

2015-01-01

Raffinose-family oligosaccharide (RFO) in soybeans is one of the major anti-nutritional factors for poultry and livestocks. α-Galactosidase is commonly supplemented into the animal feed to hydrolyze α-1,6-galactosidic bonds on the RFOs. To simplify the feed processing, a protease-resistant α-galactosidase encoding gene from Gibberella sp. strain F75, aga-F75, was modified by codon optimization and heterologously expressed in the embryos of transgentic maize driven by the embryo-specific promoter ZM-leg1A. The progenies were produced by backcrossing with the commercial inbred variety Zheng58. PCR, southern blot and western blot analysis confirmed the stable integration and tissue specific expression of the modified gene, aga-F75m, in seeds over four generations. The expression level of Aga-F75M reached up to 10,000 units per kilogram of maize seeds. In comparison with its counterpart produced in Pichia pastoris strain GS115, maize seed-derived Aga-F75M showed a lower temperature optimum (50 °C) and lower stability over alkaline pH range, but better thermal stability at 60 °C to 70 °C and resistance to feed pelleting inactivation (80 °C). This is the first report of producing α-galactosidase in transgenic plant. The study offers an effective and economic approach for direct utilization of α-galactosidase-producing maize without any purification or supplementation procedures in the feed processing.

Topical minoxidil fortified with finasteride: An account of maintenance of hair density after replacing oral finasteride.

PubMed

Chandrashekar, B S; Nandhini, T; Vasanth, Vani; Sriram, Rashmi; Navale, Shreya

2015-01-01

Finasteride acts by reducing dihydrotestosterone levels, thereby inhibiting miniaturization of hair follicles in patients with androgenetic alopecia (AGA). Oral finasteride is associated with side effects such as decreased libido, sexual dysfunction, and gynecomastia. The aim of the following study is to assess the efficacy of maintaining hair growth with 5% topical minoxidil fortified with 0.1% finasteride in patients with AGA after initial treatment with 5% topical minoxidil and oral finasteride for two years. A retrospective assessment was done in 50 male patients aged 20-40 years with AGA. All the patients had been initially treated with topical minoxidil and oral finasteride for a period of two years, after which the oral finasteride was replaced with topical minoxidil fortified with finasteride. Five of 50 patients had discontinued the treatment for a period of 8-12 months and were then resumed with only topical minoxidil fortified with finasteride. The patients' case sheets and photographs were reviewed by independent observers and the efficacy of minoxidil-finasteride combination was assessed. Of the 45 patients who underwent a continuous treatment for AGA, 84.44% maintained a good hair density with topical minoxidil-finasteride combinatio. Of the five patients who discontinued oral finasteride for 8-12 months, four demonstrated good improvement in hair density when treatment was resumed with topical minoxidil-finasteride combination. Topical finasteride can be considered for hair density maintenance after initial improvement with oral finasteride, thereby obviating the indefinite use of oral finasteride.

Auditory pathway maturational study in small for gestational age preterm infants.

PubMed

Angrisani, Rosanna Giaffredo; Diniz, Edna Maria Albuquerque; Guinsburg, Ruth; Ferraro, Alexandre Archanjo; Azevedo, Marisa Frasson de; Matas, Carla Gentile

2014-01-01

To follow up the maturation of the auditory pathway in preterm infants small for gestational age (SGA), through the study of absolute and interpeak latencies of auditory brainstem response (ABR) in the first six months of age. This multicentric prospective cross-sectional and longitudinal study assessed 76 newborn infants, 35 SGA and 41 appropriate for gestational age (AGA), born between 33 and 36 weeks in the first evaluation. The ABR was carried out in three moments (neonatal period, three months and six months). Twenty-nine SGA and 33 AGA (62 infants), between 51 and 54 weeks (corrected age), returned for the second evaluation. In the third evaluation, 49 infants (23 SGA and 26 AGA), with age range from 63 to 65 weeks (corrected age), were assessed. The bilateral presence of Transient Evoked Otoacoustic Emissions and normal tympanogram were inclusion criteria. It was found interaural symmetry in both groups. The comparison between the two groups throughout the three periods studied showed no significant differences in the ABR parameters, except for the latencies of wave III in the period between three and six months. As for the maturation with tone burst 0.5 and 1 kHz, it was found that the groups did not differ. The findings suggest that, in the premature infants, the maturational process of the auditory pathway occurs in a similar rate for SGA and AGA. These results also suggest that prematurity is a more relevant factor for the maturation of the auditory pathway than birth weight.

Basal body structure and composition in the apicomplexans Toxoplasma and Plasmodium.

PubMed

Francia, Maria E; Dubremetz, Jean-Francois; Morrissette, Naomi S

2015-01-01

The phylum Apicomplexa encompasses numerous important human and animal disease-causing parasites, including the Plasmodium species, and Toxoplasma gondii, causative agents of malaria and toxoplasmosis, respectively. Apicomplexans proliferate by asexual replication and can also undergo sexual recombination. Most life cycle stages of the parasite lack flagella; these structures only appear on male gametes. Although male gametes (microgametes) assemble a typical 9+2 axoneme, the structure of the templating basal body is poorly defined. Moreover, the relationship between asexual stage centrioles and microgamete basal bodies remains unclear. While asexual stages of Plasmodium lack defined centriole structures, the asexual stages of Toxoplasma and closely related coccidian apicomplexans contain centrioles that consist of nine singlet microtubules and a central tubule. There are relatively few ultra-structural images of Toxoplasma microgametes, which only develop in cat intestinal epithelium. Only a subset of these include sections through the basal body: to date, none have unambiguously captured organization of the basal body structure. Moreover, it is unclear whether this basal body is derived from pre-existing asexual stage centrioles or is synthesized de novo. Basal bodies in Plasmodium microgametes are thought to be synthesized de novo, and their assembly remains ill-defined. Apicomplexan genomes harbor genes encoding δ- and ε-tubulin homologs, potentially enabling these parasites to assemble a typical triplet basal body structure. Moreover, the UNIMOD components (SAS6, SAS4/CPAP, and BLD10/CEP135) are conserved in these organisms. However, other widely conserved basal body and flagellar biogenesis elements are missing from apicomplexan genomes. These differences may indicate variations in flagellar biogenesis pathways and in basal body arrangement within the phylum. As apicomplexan basal bodies are distinct from their metazoan counterparts, it may be possible to selectively target parasite structures in order to inhibit microgamete motility which drives generation of genetic diversity in Toxoplasma and transmission for Plasmodium.

Health benefits and cost-effectiveness of a hybrid screening strategy for colorectal cancer.

PubMed

Dinh, Tuan; Ladabaum, Uri; Alperin, Peter; Caldwell, Cindy; Smith, Robert; Levin, Theodore R

2013-09-01

Colorectal cancer (CRC) screening guidelines recommend screening schedules for each single type of test except for concurrent sigmoidoscopy and fecal occult blood test (FOBT). We investigated the cost-effectiveness of a hybrid screening strategy that was based on a fecal immunological test (FIT) and colonoscopy. We conducted a cost-effectiveness analysis by using the Archimedes Model to evaluate the effects of different CRC screening strategies on health outcomes and costs related to CRC in a population that represents members of Kaiser Permanente Northern California. The Archimedes Model is a large-scale simulation of human physiology, diseases, interventions, and health care systems. The CRC submodel in the Archimedes Model was derived from public databases, published epidemiologic studies, and clinical trials. A hybrid screening strategy led to substantial reductions in CRC incidence and mortality, gains in quality-adjusted life years (QALYs), and reductions in costs, comparable with those of the best single-test strategies. Screening by annual FIT of patients 50-65 years old and then a single colonoscopy when they were 66 years old (FIT/COLOx1) reduced CRC incidence by 72% and gained 110 QALYs for every 1000 people during a period of 30 years, compared with no screening. Compared with annual FIT, FIT/COLOx1 gained 1400 QALYs/100,000 persons at an incremental cost of $9700/QALY gained and required 55% fewer FITs. Compared with FIT/COLOx1, colonoscopy at 10-year intervals gained 500 QALYs/100,000 at an incremental cost of $35,100/QALY gained but required 37% more colonoscopies. Over the ranges of parameters examined, the cost-effectiveness of hybrid screening strategies was slightly more sensitive to the adherence rate with colonoscopy than the adherence rate with yearly FIT. Uncertainties associated with estimates of FIT performance within a program setting and sensitivities for flat and right-sided lesions are expected to have significant impacts on the cost-effectiveness results. In our simulation model, a strategy of annual or biennial FIT, beginning when patients are 50 years old, with a single colonoscopy when they are 66 years old, delivers clinical and economic outcomes similar to those of CRC screening by single-modality strategies, with a favorable impact on resources demand. Copyright © 2013 AGA Institute. Published by Elsevier Inc. All rights reserved.

Profiling the repertoire of phenotypes influenced by environmental cues that occur during asexual reproduction.

PubMed

Dombrovsky, Aviv; Arthaud, Laury; Ledger, Terence N; Tares, Sophie; Robichon, Alain

2009-11-01

The aphid Acyrthosiphon pisum population is composed of different morphs, such as winged and wingless parthenogens, males, and sexual females. The combined effect of reduced photoperiodicity and cold in fall triggers the apparition of sexual morphs. In contrast they reproduce asexually in spring and summer. In our current study, we provide evidence that clonal individuals display phenotypic variability within asexual morph categories. We describe that clones sharing the same morphological features, which arose from the same founder mother, constitute a repertoire of variants with distinct behavioral and physiological traits. Our results suggest that the prevailing environmental conditions influence the recruitment of adaptive phenotypes from a cohort of clonal individuals exhibiting considerable molecular diversity. However, we observed that the variability might be reduced or enhanced by external factors, but is never abolished in accordance with a model of stochastically produced phenotypes. This overall mechanism allows the renewal of colonies from a few adapted individuals that survive drastic episodic changes in a fluctuating environment.

High-Throughput Assay and Discovery of Small Molecules that Interrupt Malaria Transmission

PubMed Central

Plouffe, David M.; Wree, Melanie; Du, Alan Y.; Meister, Stephan; Li, Fengwu; Patra, Kailash; Lubar, Aristea; Okitsu, Shinji L.; Flannery, Erika L.; Kato, Nobutaka; Tanaseichuk, Olga; Comer, Eamon; Zhou, Bin; Kuhen, Kelli; Zhou, Yingyao; Leroy, Didier; Schreiber, Stuart L.; Scherer, Christina A.; Vinetz, Joseph; Winzeler, Elizabeth A.

2016-01-01

Summary Preventing transmission is an important element of malaria control. However, most of the current available methods to assay for malaria transmission blocking are relatively low throughput and cannot be applied to large chemical libraries. We have developed a high-throughput and cost-effective assay, the Saponin-lysis Sexual Stage Assay (SaLSSA), for identifying small molecules with transmission-blocking capacity. SaLSSA analysis of 13,983 unique compounds uncovered that >90% of well-characterized antimalarials, including endoperoxides and 4-aminoquinolines, as well as compounds active against asexual blood stages, lost most of their killing activity when parasites developed into metabolically quiescent stage V gametocytes. On the other hand, we identified compounds with consistent low nanomolar transmission-blocking activity, some of which showed cross-reactivity against asexual blood and liver stages. The data clearly emphasize substantial physiological differences between sexual and asexual parasites and provide a tool and starting points for the discovery and development of transmission-blocking drugs. PMID:26749441

Sexual reproduction as a response to H sub 2 O sub 2 damage in Schizosaccharomyces pombe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernstein, C.; Johns, V.

1989-04-01

Although sexual reproduction is widespread, its adaptive advantage over asexual reproduction is unclear. One major advantage of sex may be its promotion of recombinational repair of DNA damage during meiosis. This idea predicts that treatment of the asexual form of a facultatively sexual-asexual eucaryote with a DNA-damaging agent may cause it to enter the sexual cycle more frequently. Endogenous hydrogen peroxide is a major natural source of DNA damage. Thus, the authors treated vegetative cells of Schizosaccharomyces pombe with hydrogen peroxide to test if sexual reproduction increases. Among untreated stationary-phase S. pombe populations the sexual spores produced by meiosis representedmore » about 1% of the total cells. However, treatment of late-exponential-phase vegetative cells with hydrogen peroxide increased the percentage of meiotic spores in the stationary phase by 4- to 18-fold. Oxidative damage therefore induces sexual reproduction in a facultatively sexual organism, a result expected by the hypothesis that sex promotes DNA repair.« less

Profiling the repertoire of phenotypes influenced by environmental cues that occur during asexual reproduction

PubMed Central

Dombrovsky, Aviv; Arthaud, Laury; Ledger, Terence N.; Tares, Sophie; Robichon, Alain

2009-01-01

The aphid Acyrthosiphon pisum population is composed of different morphs, such as winged and wingless parthenogens, males, and sexual females. The combined effect of reduced photoperiodicity and cold in fall triggers the apparition of sexual morphs. In contrast they reproduce asexually in spring and summer. In our current study, we provide evidence that clonal individuals display phenotypic variability within asexual morph categories. We describe that clones sharing the same morphological features, which arose from the same founder mother, constitute a repertoire of variants with distinct behavioral and physiological traits. Our results suggest that the prevailing environmental conditions influence the recruitment of adaptive phenotypes from a cohort of clonal individuals exhibiting considerable molecular diversity. However, we observed that the variability might be reduced or enhanced by external factors, but is never abolished in accordance with a model of stochastically produced phenotypes. This overall mechanism allows the renewal of colonies from a few adapted individuals that survive drastic episodic changes in a fluctuating environment. PMID:19635846

Observations of asexual reproductive strategies in Antarctic hexactinellid sponges from ROV video records

NASA Astrophysics Data System (ADS)

Teixidó, Núria; Gili, Josep-Maria; Uriz, María-J.; Gutt, Julian; Arntz, Wolf E.

2006-04-01

Hexactinellid sponges are one of the structuring taxa of benthic communities on the Weddell Sea shelf (Antarctica). However, little is known about their reproduction patterns (larval development, release, settlement, and recruitment), particularly in relation to sexual and asexual processes in sponge populations. Video stations obtained during several expeditions covering a wide depth range and different areas recorded a high frequency of asexual reproductive strategies (ARS) (bipartition and budding) among hexactinellids. Analysis of seabed video strips between 108 and 256 m depth, representing an area of 1400 m 2, showed that about 28% of these sponges exhibited ARS. The Rossella nuda type dominated most of the video stations and exhibited the highest proportion of budding (35%). This proportion increased with the size class. Size class >20 cm exhibited in all the stations a mean value of 8.3±0.7 (SE) for primary and of 2.5±0.2 (SE) for secondary propagules per sponge, respectively. Results from a shallow station (Stn 059, 117 m depth) showed the highest relative abundance of R. nuda type and budding (>20 cm ˜72%, 10-20 cm ˜60%, 5-10 cm ˜12%, and <5 cm ˜3%). A potential influence of iceberg scouring disturbance on the occurrence of budding and number of propagules also was investigated. We conclude that asexual reproduction in hexactinellid sponges may be more frequent than has been thought before and it may greatly influence the genetic structure of populations.

The role of hybridization in the origin and spread of asexuality in Daphnia

PubMed Central

Xu, Sen; Innes, David J.; Lynch, Michael; Cristescu, Melania E.

2014-01-01

The molecular mechanisms leading to asexuality remain little understood despite their substantial bearing on why sexual reproduction is dominant in nature. Here we examine the role of hybridization in the origin and spread of obligate asexuality in Daphnia pulex, arguably the best-documented case of contagious asexuality. Obligately parthenogenetic (OP) clones of D. pulex have traditionally been separated into “hybrid” (Ldh SF) and “non-hybrid” (Ldh SS) forms because the lactase dehydrogenase (Ldh) locus distinguishes the cyclically parthenogenetic (CP) lake dwelling Daphnia pulicaria (Ldh FF) from its ephemeral pond dwelling sister species D. pulex (Ldh SS). The results of our population genetic analyses based on microsatellite loci suggest that both Ldh SS and SF OP individuals can originate from the crossing of CP female F1 (D. pulex × D. pulicaria) and backcrosses with males from OP lineages carrying genes that suppress meiosis specifically in female offspring. In previous studies, a suite of diagnostic markers was found to be associated with OP in Ldh SS D. pulex lineages. Our association mapping supports a similar genetic mechanism for the spread of obligate parthenogenesis in Ldh SF OP individuals. Interestingly, our study shows that CP D. pulicaria carry many of the diagnostic microsatellite alleles associated with obligate parthenogenesis. We argue that the assemblage of mutations that suppress meiosis and underlie obligate parthenogenesis in D. pulex originated due to a unique historical hybridization and introgression event between D. pulex and D. pulicaria. PMID:23879327

[The effects of electro-acupuncture on the signaling pathway of TLR/MYD88 in ankle joint synovial tissue of acute gouty arthritis rats].

PubMed

Zhang, Chao-nan; Huang, Xue-kuan; Luo, Yan; Jiang, Juan; Wan, Lei; Wang, Ling

2014-11-01

To investigate the effects of electro-acupuncture ( EA) on the related protein expression of the signaling pathway of the toll-like receptor2 (TLR2)/myeloid differentiation factor (MYD) 88 in ankle joint synovial tissue of acute gouty arthritis (AGA) rats. Fifty male SD rats were randomly divided into 5 groups: normal group, SMD group, AGA model group, medication group and EA group, 10 rats in each group. SMD group established model by inducing SMD, other groups established AGA model by inducing monosodium urate, except the normal group. Two days before model was established, normal and SMD and AGA model groups were lavaged with normal saline (20 mL/kg), medication group was lavaged with colchicine solution (1 mg/kg), EA (1. 5-2 Hz, D.-D. wave, 9 V, 1-3 mA) was applied to"Sanyinjiao" (SP6),"Jiexi"(ST41) and "kunlun" (BL60) for 20 min, once daily, continuously for 9 days. Then the join sewlling index was observed periodically, the protein expression of TLR2 and MYD88 was determined by immunohistochemistry. Compared to the normal group, the join sewlling of the SMD group in test join increased significantly (P<0. 05) and the protein expression of TLR2 and MYD88 in synovial tissue has not statistically significant (P>0.05), the oin sewlling and protein expression of TLR2 and MYD88 in synovial tissue of model group increased significantly P<0. 05); The medication and EA group compared to the model group, the protein expression of TLR2 and MYD88 in synovial tissue decreased significantly (P <0. 05), the join sewlling in test join decreased significantly P<1. 05); There were not statistically significant between the EA group and the medication group (P>0.05). EA can alleviate the symptoms of AGA, which may be related to regulation of the protein expression Y TRI and MYD88 in the TLR/MYD88 signaling pathway.

Left-dominant arrhythmogenic cardiomyopathy in a large family: associated desmosomal or nondesmosomal genotype?

PubMed

Groeneweg, Judith A; van der Zwaag, Paul A; Jongbloed, Jan D H; Cox, Moniek G P J; Vreeker, Arnold; de Boer, Rudolf A; van der Heijden, Jeroen F; van Veen, Toon A B; McKenna, William J; van Tintelen, J Peter; Dooijes, Dennis; Hauer, Richard N W

2013-04-01

Arrhythmogenic cardiomyopathy (AC) is considered a predominantly right ventricular (RV) desmosomal disease. However, left-dominant forms due to desmosomal gene mutations, including PKP2 variant c.419C>T, have been described. Recently, a nondesmosomal phospholamban (PLN) mutation (c.40_42delAGA) has been identified, causing dilated cardiomyopathy and arrhythmias. To gain more insight into pathogenicity of the PKP2 variant c.419C>T by cosegregation analysis of the PKP2 variant c.419C>T vs the PLN mutation c.40_42delAGA. A Dutch family (13 family members, median age 49 years, range 34-71 years) with ventricular tachycardia underwent (1) meticulous phenotypic characterization and (2) screening of 5 desmosomal genes (PKP2, DSC2, DSG2, DSP, JUP) and PLN. Six family members fulfilled 2010 AC Task Force Criteria. Seven had signs of left ventricular (LV) involvement (inverted T waves in leads V4-V6, LV wall motion abnormalities and late enhancement, and reduced LV ejection fraction), including 6 family members with proven AC. The PKP2 variant c.419C>T was found as a single variant in 3 family members, combined with the PLN mutation c.40_42delAGA in 3 others. PLN mutation was found in 9 family members, including the 6 with AC and all 7 with LV involvement. The PLN mutation c.40_42delAGA was found as a single mutation in 6, combined with the PKP2 variant c.419C>T in 3 others. A low-voltage electrocardiogram was seen in 4 of 9 PLN mutation-positive subjects. None of the family members with the single PKP2 variant showed any sign of RV or LV involvement. The PLN mutation c.40_42delAGA cosegregates with AC and with electrocardiographic and structural LV abnormalities. In this family, there was no evidence of disease-causing contribution of the PKP2 variant c.419C>T. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Randomized outcome trial of nutrient-enriched formula and neurodevelopment outcome in preterm infants.

PubMed

Giannì, Maria Lorella; Roggero, Paola; Amato, Orsola; Picciolini, Odoardo; Piemontese, Pasqua; Liotto, Nadia; Taroni, Francesca; Mosca, Fabio

2014-03-19

Preterm infants are at risk for adverse neurodevelopment. Furthermore, nutrition may play a key role in supporting neurodevelopment. The aim of this study was to evaluate whether a nutrient-enriched formula fed to preterm infants after hospital discharge could improve their neurodevelopment at 24 months (term-corrected age). We conducted an observer-blinded, single-center, randomized controlled trial in infants admitted to the Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, University of Milan, Italy between 2009 and 2011. Inclusion criteria were gestational age < 32 weeks and/or birth weight < 1500 g, and being fed human milk for < 20% of the total milk intake. Exclusion criteria were congenital malformations or conditions that could interfere with growth or body composition. Included infants were randomized to receive a standard full-term formula or a nutrient-enriched formula up until 6 months of corrected age, using two computer-generated randomization lists; one appropriate for gestational age (AGA) and one for small for gestational age (SGA) infants. We assessed neurodevelopment at 24 months of corrected age using the Griffiths Mental Development Scale and related subscales (locomotor, personal-social, hearing and speech, hand and eye coordination, and performance). Of the 207 randomized infants, 181 completed the study. 52 AGA and 35 SGA infants were fed a nutrient-enriched formula, whereas 56 AGA and 38 SGA infants were fed a standard full-term formula. The general quotient at 24 months of corrected age was not significantly different between infants randomized to receive a nutrient-enriched formula compared with a standard term formula up until 6 months of corrected age (AGA infants: 93.8 ± 12.6 vs. 92.4 ± 10.4, respectively; SGA infants: 96.1 ± 9.9 vs. 98.2 ± 9, respectively). The scores of related subscales were also similar among groups. This study found that feeding preterm infants a nutrient-enriched formula after discharge does not affect neurodevelopment at 24 months of corrected age, in either AGA or SGA infants, free from major comorbidities. Current Controlled Trials (http://www.controlled-trials.com/ISRCTN30189842) London, UK.

Low-level laser therapy as a treatment for androgenetic alopecia.

PubMed

Afifi, Ladan; Maranda, Eric L; Zarei, Mina; Delcanto, Gina M; Falto-Aizpurua, Leyre; Kluijfhout, Wouter P; Jimenez, Joaquin J

2017-01-01

Androgenetic alopecia (AGA) affects 50% of males by age 50 and 50% of females by age 80. Recently, the use of low-level laser therapy (LLLT) has been proposed as a treatment for hair loss and to stimulate hair regrowth in AGA. This paper aims to review the existing research studies to determine whether LLLT is an effective therapy for AGA based on objective measurements and patient satisfaction. A systematic literature review was done to identify articles on Medline, Google Scholar, and Embase that were published between January 1960 and November 2015. All search hits were screened by two reviewers and examined for relevant abstracts and titles. Articles were divided based on study design and assessed for risk of bias. Eleven studies were evaluated, which investigated a total of 680 patients, consisting of 444 males and 236 females. Nine out of 11 studies assessing hair count/hair density found statistically significant improvements in both males and females following LLLT treatment. Additionally, hair thickness and tensile strength significantly improved in two out of four studies. Patient satisfaction was investigated in five studies, and was overall positive, though not as profound as the objective outcomes. The majority of studies covered in this review found an overall improvement in hair regrowth, thickness, and patient satisfaction following LLLT therapy. Although we should be cautious when interpreting these findings, LLLT therapy seems to be a promising monotherapy for AGA and may serve as an effective alternative for individuals unwilling to use medical therapy or undergo surgical options. Lasers Surg. Med. 49:27-39, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

A Proposal of an Effective Platelet-rich Plasma Protocol for the Treatment of Androgenetic Alopecia

PubMed Central

Ferrando, Juan; García-García, Sandra Cecilia; González-de-Cossío, Ana Cecilia; Bou, Lola; Navarra, Esperanza

2017-01-01

Background: Platelet-rich plasma (PRP) has emerged as a promising treatment for androgenetic alopecia (AGA). In spite of the several studies previously reported, to date, a standardized protocol for PRP preparation and application, as well as a standard method for evaluating results has not been established. Aims: The aim of this study is to propose a standardized method for preparation and application of PRP for male AGA (MAGA) and female AGA (FAGA) and assess its safety and efficacy as a co-adjuvant therapy. Materials and Methods: Seventy-eight patients, 19 men and 59 women with AGA Grades II–IV in Ebling's scale, currently on treatment with topical minoxidil and/or oral finasteride for more than a year without improvement, were included in this study. PRP was prepared using a single spin method, and injected in affected areas for 3 monthly sessions, followed by 3 bimonthly sessions. A decrease of at least one grade in Ebling's scale was considered a successful result. Results: After the 6° session, 71.4% of MAGA and 73.4% of FAGA patients reached a successful outcome while 21.4% and 16.3%, respectively, remained without changes. Only 7.1% of MAGA and 10.2% of FAGA presented worsening of their condition. Conclusions: PRP together with a periodical application protocol can be considered effective as a coadjuvant therapy in patients who no longer respond to pharmacological treatments. Ebling's scale was a practical and reliable parameter to allow a better evaluation in both MAGA and FAGA. PMID:29118521

The effect of sex on the repeatability of evolution in different environments.

PubMed

Lachapelle, Josianne; Colegrave, Nick

2017-04-01

The adaptive function of sex has been extensively studied, while less consideration has been given to the potential downstream consequences of sex on evolution. Here, we investigate one such potential consequence, the effect of sex on the repeatability of evolution. By affecting the repeatability of evolution, sex could have important implications for biodiversity, and for our ability to make predictions about the outcome of environmental change. We allowed asexual and sexual populations of Chlamydomonas reinhardtii to evolve in novel environments and monitored both their change in fitness and variance in fitness after evolution. Sex affected the repeatability of evolution by changing the importance of the effect of selection, chance, and ancestral constraints on the outcome of the evolutionary process. In particular, the effects of sex were highly dependent on the initial genetic composition of the population and on the environment. Given the lack of a consistent effect of sex on repeatability across the environments used here, further studies to dissect in more detail the underlying reasons for these differences as well as studies in additional environments are required if we are to have a general understanding of the effects of sex on the repeatability of evolution. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Epistasis increases the rate of conditionally neutral substitution in an adapting population.

PubMed

Draghi, Jeremy A; Parsons, Todd L; Plotkin, Joshua B

2011-04-01

Kimura observed that the rate of neutral substitution should equal the neutral mutation rate. This classic result is central to our understanding of molecular evolution, and it continues to influence phylogenetics, genomics, and the interpretation of evolution experiments. By demonstrating that neutral mutations substitute at a rate independent of population size and selection at linked sites, Kimura provided an influential justification for the idea of a molecular clock and emphasized the importance of genetic drift in shaping molecular evolution. But when epistasis among sites is common, as numerous empirical studies suggest, do neutral mutations substitute according to Kimura's expectation? Here we study simulated, asexual populations of RNA molecules, and we observe that conditionally neutral mutations--i.e., mutations that do not alter the fitness of the individual in which they arise, but that may alter the fitness effects of subsequent mutations--substitute much more often than expected while a population is adapting. We quantify these effects using a simple population-genetic model that elucidates how the substitution rate at conditionally neutral sites depends on the population size, mutation rate, strength of selection, and prevalence of epistasis. We discuss the implications of these results for our understanding of the molecular clock, and for the interpretation of molecular variation in laboratory and natural populations.

Epistasis Increases the Rate of Conditionally Neutral Substitution in an Adapting Population

PubMed Central

Draghi, Jeremy A.; Parsons, Todd L.; Plotkin, Joshua B.

2011-01-01

Kimura observed that the rate of neutral substitution should equal the neutral mutation rate. This classic result is central to our understanding of molecular evolution, and it continues to influence phylogenetics, genomics, and the interpretation of evolution experiments. By demonstrating that neutral mutations substitute at a rate independent of population size and selection at linked sites, Kimura provided an influential justification for the idea of a molecular clock and emphasized the importance of genetic drift in shaping molecular evolution. But when epistasis among sites is common, as numerous empirical studies suggest, do neutral mutations substitute according to Kimura's expectation? Here we study simulated, asexual populations of RNA molecules, and we observe that conditionally neutral mutations—i.e., mutations that do not alter the fitness of the individual in which they arise, but that may alter the fitness effects of subsequent mutations—substitute much more often than expected while a population is adapting. We quantify these effects using a simple population-genetic model that elucidates how the substitution rate at conditionally neutral sites depends on the population size, mutation rate, strength of selection, and prevalence of epistasis. We discuss the implications of these results for our understanding of the molecular clock, and for the interpretation of molecular variation in laboratory and natural populations. PMID:21288876

The hawk-dove game in a sexually reproducing species explains a colourful polymorphism of an endangered bird.

PubMed

Kokko, Hanna; Griffith, Simon C; Pryke, Sarah R

2014-10-22

The hawk-dove game famously introduced strategic game theory thinking into biology and forms the basis of arguments for limited aggression in animal populations. However, aggressive 'hawks' and peaceful 'doves', with strategies inherited in a discrete manner, have never been documented in a real animal population. Thus, the applicability of game-theoretic arguments to real populations might be contested. Here, we show that the head-colour polymorphism of red and black Gouldian finches (Erythrura gouldiae) provides a real-life example. The aggressive red morph is behaviourally dominant and successfully invades black populations, but when red 'hawks' become too common, their fitness is severely compromised (via decreased parental ability). We also investigate the effects of real-life deviations, particularly sexual reproduction, from the simple original game, which assumed asexual reproduction. A protected polymorphism requires mate choice to be sufficiently assortative. Assortative mating is adaptive for individuals because of genetic incompatibilities affecting hybrid offspring fitness, but by allowing red 'hawks' to persist, it also leads to significantly reduced population sizes. Because reductions in male contributions to parental care are generally known to lead to lower population productivity in birds, we expect zero-sum competition to often have wide ranging population consequences. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

A novel α-galactosidase from the thermophilic probiotic Bacillus coagulans with remarkable protease-resistance and high hydrolytic activity

PubMed Central

Zhao, Ruili; Zhao, Rui; Tu, Yishuai; Zhang, Xiaoming; Deng, Liping

2018-01-01

A novel α-galactosidase of glycoside hydrolase family 36 was cloned from Bacillus coagulans, overexpressed in Escherichia coli, and characterized. The purified enzyme Aga-BC7050 was 85 kDa according to SDS-PAGE and 168 kDa according to gel filtration, indicating that its native structure is a dimer. With p-nitrophenyl-α-d- galactopyranoside (pNPGal) as the substrate, optimal temperature and pH were 55 °C and 6.0, respectively. At 60 °C for 30 min, it retained > 50% of its activity. It was stable at pH 5.0–10.0, and showed remarkable resistance to proteinase K, subtilisin A, α-chymotrypsin, and trypsin. Its activity was not inhibited by glucose, sucrose, xylose, or fructose, but was slightly inhibited at galactose concentrations up to 100 mM. Aga-BC7050 was highly active toward pNPGal, melibiose, raffinose, and stachyose. It completely hydrolyzed melibiose, raffinose, and stachyose in < 30 min. These characteristics suggest that Aga-BC7050 could be used in feed and food industries and sugar processing. PMID:29738566

Exploring the Role of Different Neonatal Nutrition Regimens during the First Week of Life by Urinary GC-MS Metabolomics

PubMed Central

Dessì, Angelica; Murgia, Antonio; Agostino, Rocco; Pattumelli, Maria Grazia; Schirru, Andrea; Scano, Paola; Fanos, Vassilios; Caboni, Pierluigi

2016-01-01

In this study, a gas-chromatography mass spectrometry (GC-MS) metabolomics study was applied to examine urine metabolite profiles of different classes of neonates under different nutrition regimens. The study population included 35 neonates, exclusively either breastfed or formula milk fed, in a seven-day timeframe. Urine samples were collected from intrauterine growth restriction (IUGR), large for gestational age (LGA), and appropriate gestational age (AGA) neonates. At birth, IUGR and LGA neonates showed similarities in their urine metabolite profiles that differed from AGA. When neonates started milk feeding, their metabolite excretion profile was strongly characterized by the different diet regimens. After three days of formula milk nutrition, urine had higher levels of glucose, galactose, glycine and myo-inositol, while up-regulated aconitic acid, aminomalonic acid and adipic acid were found in breast milk fed neonates. At seven days, neonates fed with formula milk shared higher levels of pseudouridine with IUGR and LGA at birth. Breastfed neonates shared up-regulated pyroglutamic acid, citric acid, and homoserine, with AGA at birth. The role of most important metabolites is herein discussed. PMID:26907266

Circulating GLP-1 in infants born small-for-gestational-age: breast-feeding versus formula-feeding.

PubMed

Díaz, M; Bassols, J; Sebastiani, G; López-Bermejo, A; Ibáñez, L; de Zegher, F

2015-10-01

Prenatal growth restraint associates with the risk for later diabetes, particularly if such restraint is followed by postnatal formula-feeding (FOF) rather than breast-feeding (BRF). Circulating incretins can influence the neonatal programming of hypothalamic setpoints for appetite and energy expenditure, and are thus candidate mediators of the long-term effects exerted by early nutrition. We have tested this concept by measuring (at birth and at age 4 months) the circulating concentrations of glucagon-like peptide-1 (GLP-1) in BRF infants born appropriate-for-gestational-age (AGA; n=63) and in small-for-gestational-age (SGA) infants receiving either BRF (n=28) or FOF (n=26). At birth, concentrations of GLP-1 were similar in AGA and SGA infants. At 4 months, pre-feeding GLP-1 concentrations were higher than at birth; SGA-BRF infants had GLP-1 concentrations similar to those in AGA-BRF infants but SGA-FOF infants had higher concentrations. In conclusion, nutrition appears to influence the circulating GLP-1 concentrations in SGA infants and may thereby modulate long-term diabetes risk.

Expression and enzymatic characterization of a cold-adapted β-agarase from Antarctic bacterium Pseudoalteromonas sp. NJ21

NASA Astrophysics Data System (ADS)

Li, Jiang; Sha, Yujie

2015-03-01

An agar-degrading bacterium, designated as Pseudoalteromonas sp. NJ21, was isolated from an Antarctic sediment sample. The agarase gene aga1161 from Pseudoalteromonas sp. NJ21 consisting of a 2 382-bp coding region was cloned. The gene encodes a 793-amino acids protein and was found to possess characteristic features of the Glyco_hydro_42 family. The recombinant agarase (rAga1161) was overexpressed in Escherichia coli and purified as a fusion protein. Enzyme activity analysis revealed that the optimum temperature and pH for the purified recombinant agarase were 30-40°C and 8.0, respectively. rAga1161 was found to maintain as much as 80% of its maximum activity at 10°C, which is typical of a coldadapted enzyme. The pattern of agar hydrolysis demonstrated that the enzyme is an β-agarase, producing neoagarobiose (NA2) as the final main product. Furthermore, this work is the first proof of an agarolytic activity in Antarctic bacteria and these results indicate the potential for the Antarctic agarase as a catalyst in medicine, food and cosmetic industries.

On the Uselessness of Men - Comparison of Sexual and Asexual Reproduction

NASA Astrophysics Data System (ADS)

Stauffer, D.; Sá Martins, J. S.; de Oliveira, S. Moss

A comparison of sexual with asexual reproduction in the Penna aging model for a single species shows the separation into males and females at a disadvantage due to the halved number of births. Also meiotic and apomictic parthenogenesis and hermaphroditism seem better than sex, even when the individuals follow the suggestion of Jan et al. to engage in sex only when their lifes are endangered by a large number of harmful mutations. In our comparison, we looked only for intrinsic effects, not for external influences like parasites or environmental catastrophes.

Solar system 'fast mission' trajectories using aerogravity assist

NASA Technical Reports Server (NTRS)

Randolph, James E.; Mcronald, Angus D.

1992-01-01

Initial analyses of the aerogravity assist (AGA) delivery technique to solar system targets (and beyond) has been encouraging. Mission opportunities are introduced that do not exist with typical gravity assist trajectories and current launch capabilities. The technique has the most payoff for high-energy missions such as outer planet orbiters and flybys. The goal of this technique is to reduce the flight duration significantly and to eliminate propulsion for orbit insertion. The paper will discuss detailed analyses and parametric studies that consider launch opportunities for missions to the sun, Saturn, Uranus, Neptune, and Pluto using AGA at Venus and Mars.

Comparison of the Efficacy of Homologous and Autologous Platelet-Rich Plasma (PRP) for Treating Androgenic Alopecia.

PubMed

Ince, Bilsev; Yildirim, Mehmet Emin Cem; Dadaci, Mehmet; Avunduk, Mustafa Cihat; Savaci, Nedim

2018-02-01

Androgenetic alopecia (AGA), the most common cause of hair loss in both sexes, accounts for 95% of all cases of hair loss. Although the literature has suggested that both nonactivated (n-PRP) and activated autologous (a-PRP) PRP can be used to treat AGA, we did not find any study investigating the use of homologous PRP (h-PRP) for this purpose. Also, to the best of our knowledge, there are no studies comparing the efficacy of h-PRP, a-PRP, or n-PRP on AGA therapy. The aim of this study was to compare the increase in hair density, average number of platelets, complications, preparation, and duration of application in the treatment of AGA using a-PRP, n-PRP, and h-PRP. Between 2014 and 2015, we studied male patients who had experienced increased hair loss in the last year. Patients were divided into three groups: Group 1 received n-PRP, Group 2 received active PRP, and Group 3 received h-PRP. For Group 1, PRP was prepared by a single centrifugation prepared from the patient's own blood. For Group 2, the PRP was prepared from the patient's own blood, but a second centrifugation was applied for platelet activation with calcium chloride. For Group 3, the PRP was prepared from pooled platelets with the same blood group as the patient from the blood center. PRP was injected at 1, 2, and 6 months. The hair density (n/cm 2 ) of each patient before and after injection was calculated. Each patient was assigned a fixed evaluation point at the time of application to calculate hair density. At 2, 6, and 12 months after the first treatment, the increase in hair density was calculated as 11.2, 26.1, and 32.4%, respectively, in Group 1; 8.1, 12.5, and 20.8%, respectively, in Group 2; and 16.09, 36.41, and 41.76%, respectively, in Group 3. The increase in hair density was statistically significantly greater in Group 1 than in Group 2 and more so in Group 3 than in both groups among all controls (p < 0.05). The efficacy of both PRPs was determined in AGA treatment in our study. However, it was determined statistically that the increase in hair density with h-PRP was greater than with autologous PRP groups. We believe that h-PRP therapy can be used in patients with AGA presenting with hair loss. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Invasion of novel habitats uncouples haplo-diplontic life cycles.

PubMed

Krueger-Hadfield, Stacy A; Kollars, Nicole M; Byers, James E; Greig, Thomas W; Hammann, Mareike; Murray, David C; Murren, Courtney J; Strand, Allan E; Terada, Ryuta; Weinberger, Florian; Sotka, Erik E

2016-08-01

Baker's Law predicts uniparental reproduction will facilitate colonization success in novel habitats. While evidence supports this prediction among colonizing plants and animals, few studies have investigated shifts in reproductive mode in haplo-diplontic species in which both prolonged haploid and diploid stages separate meiosis and fertilization in time and space. Due to this separation, asexual reproduction can yield the dominance of one of the ploidy stages in colonizing populations. We tested for shifts in ploidy and reproductive mode across native and introduced populations of the red seaweed Gracilaria vermiculophylla. Native populations in the northwest Pacific Ocean were nearly always attached by holdfasts to hard substrata and, as is characteristic of the genus, haploid-diploid ratios were slightly diploid-biased. In contrast, along North American and European coastlines, introduced populations nearly always floated atop soft-sediment mudflats and were overwhelmingly dominated by diploid thalli without holdfasts. Introduced populations exhibited population genetic signals consistent with extensive vegetative fragmentation, while native populations did not. Thus, the ecological shift from attached to unattached thalli, ostensibly necessitated by the invasion of soft-sediment habitats, correlated with shifts from sexual to asexual reproduction and slight to strong diploid bias. We extend Baker's Law by predicting other colonizing haplo-diplontic species will show similar increases in asexuality that correlate with the dominance of one ploidy stage. Labile mating systems likely facilitate colonization success and subsequent range expansion, but for haplo-diplontic species, the long-term eco-evolutionary impacts will depend on which ploidy stage is lost and the degree to which asexual reproduction is canalized. © 2016 John Wiley & Sons Ltd.

Effects of functionally asexual reproduction on quantitative genetic variation in the evening primroses (Oenothera, Onagraceae).

PubMed

Godfrey, Ryan M; Johnson, Marc T J

2014-11-01

It has long been predicted that a loss of sexual reproduction leads to decreased heritable variation within populations and increased differentiation between populations. Despite an abundance of theory, there are few empirical tests of how sex affects genetic variation in phenotypic traits, especially for plants. Here we test whether repeated losses of two critical components of sex (recombination and segregation) in the evening primroses (Oenothera L., Onagraceae) affect quantitative genetic variation within and between populations. We sampled multiple genetic families from 3-5 populations from each of eight Oenothera species, which represented four independent transitions between sexual reproduction and a functionally asexual genetic system called "permanent translocation heterozygosity." We used quantitative genetics methods to partition genetic variation within and between populations for eight plant traits related to growth, leaf physiology, flowering, and resistance to herbivores. Heritability was, on average, 74% higher in sexual Oenothera populations than in functionally asexual populations, with plant growth rate, specific leaf area, and the percentage of leaf water content showing the strongest differences. By contrast, genetic differentiation among populations was 2.8× higher in functionally asexual vs. sexual Oenothera species. This difference was particularly strong for specific leaf area. Sexual populations tended to exhibit higher genetic correlations among traits, but this difference was weakly supported. These results support the prediction that sexual reproduction maintains higher genetic variation within populations, which may facilitate adaptive evolution. We also found partial support for the prediction that a loss of sex leads to greater population differentiation, which may elevate speciation rates. © 2014 Botanical Society of America, Inc.

Facultative use of thelytokous parthenogenesis for queen production in the polyandrous ant Cataglyphis cursor.

PubMed

Doums, C; Cronin, A L; Ruel, C; Fédérici, P; Haussy, C; Tirard, C; Monnin, T

2013-07-01

The evolutionary paradox of sex remains one of the major debates in evolutionary biology. The study of species capable of both sexual and asexual reproduction can elucidate factors important in the evolution of sex. One such species is the ant Cataglyphis cursor, where the queen maximizes the transmission of her genes by producing new queens (gynes) asexually while simultaneously maintaining a genetically diverse workforce via the sexual production of workers. We show that the queen can also produce gynes sexually and may do so to offset the costs of asexual reproduction. We genotyped 235 gynes from 18 colonies and found that half were sexually produced. A few colonies contained both sexually and asexually produced gynes. Although workers in this species can also use thelytoky, we found no evidence of worker production of gynes based on genotypes of 471 workers from the six colonies producing sexual gynes. Gynes are thus mainly, and potentially exclusively, produced by the queen. Simulations of gynes inbreeding level following one to ten generations of automictic thelytoky suggest that the queen switches between or combines thelytoky and sex, which may reduce the costs of inbreeding. This is supported by the relatively small size of inbred gynes in one colony, although we found no relationship between the level of inbreeding and immune parameters. Such facultative use of sex and thelytoky by individual queens contrasts with other known forms of parthenogenesis in ants, which are typically characterized by distinct lineages specializing in one strategy or the other. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

The genetics of obligate parthenogenesis in an aphid species and its consequences for the maintenance of alternative reproductive modes.

PubMed

Dedryver, C-A; Le Gallic, J-F; Mahéo, F; Simon, J-C; Dedryver, F

2013-01-01

Although loss of sex is widespread among metazoans, the genetic mechanisms underlying the transition to asexuality are poorly understood. Aphids are good models to address this issue because they frequently show reproductive-mode variation at the species level, involving cyclical parthenogens (CP) that reproduce sexually once a year and obligate parthenogens (OP) that reproduce asexually all year round. Here, we explore the genetic basis of OP in the cereal aphid Sitobion avenae by crossing several genotypes with contrasting reproductive modes and then characterising the reproductive phenotypes of F1 and F2 offspring. The analysis of phenotypic variation in F1 and F2 progenies suggests that at least two autosomal loci control OP in S. avenae. First, the transition to asexuality seems to depend on a single recessive locus, because the offspring from self-crossed cyclical parthenogenetic genotypes contain either 0 or 25% OP. Second, as we observed OP in the F1 progenies from crosses between CP and OP, and some CP in the offspring from outcrossed OP, a dominant 'suppressor' gene may also be involved, being inactive when in a recessive homozygous state in CP; this is the most parsimonious explanation for these results. This oligogenic inheritance of OP in S. avenae appears to be an efficient genetic system to generate new OP genotypes continually. It also allows asexuality-inducing alleles to be protected locally during harsh winters when extreme frost kills most OP, and then to spread very quickly after winter.

Modelling the Geographical Range of a Species with Variable Life-History

PubMed Central

Macfadyen, Sarina; Kriticos, Darren J.

2012-01-01

We show how a climatic niche model can be used to describe the potential geographic distribution of a pest species with variable life-history, and illustrate how to estimate biogeographic pest threats that vary across space. The models were used to explore factors that affect pest risk (irrigation and presences of host plant). A combination of current distribution records and published experimental data were used to construct separate models for the asexual and sexual lineages of Rhopalosiphum padi (Linnaeus) (Hemiptera: Aphididae). The two models were combined with knowledge of host plant presence to classify the global pest risk posed by R. padi. Whilst R. padi has a relatively limited area in which sexual lineages can persist year round, a much larger area is suitable for transient sexual and asexual lineages to exist. The greatest risk of establishment of persistent sexual and asexual populations is in areas with warm temperate climates. At the global scale the models show very little difference in risk patterns between natural rainfall and irrigation scenarios, but in Australia, the amount of land suitable for persistent asexual and transient sexual populations decreases (by 20%) if drought stress is no longer alleviated by irrigation. This approach proved useful for modelling the potential distribution of a species that has a variable life-history. We were able to use the model outputs to examine factors such as irrigation practices and host plant presence that altered the nature (transient or permanent) and extent of pest risk. The composite niche maps indicate pest risk in terms that are useful to both biosecurity agencies and pest managers. PMID:22808133

Molecular evidence that the asexual industrial fungus Trichoderma reesei is a clonal derivative of the ascomycete Hypocrea jecorina.

PubMed Central

Kuhls, K; Lieckfeldt, E; Samuels, G J; Kovacs, W; Meyer, W; Petrini, O; Gams, W; Börner, T; Kubicek, C P

1996-01-01

The relationship of the important cellulase producing asexual fungus Trichoderma reesei to its putative teleomorphic (sexual) ancestor Hypocrea jecorina and other species of the Trichoderma sect. Longibrachiatum was studied by PCR-fingerprinting and sequence analyses of the nuclear ribosomal DNA region containing the internal transcribed spacers (ITS-1 and ITS-2) and the 5.8S rRNA gene. The differences in the corresponding ITS sequences allowed a grouping of anamorphic (asexual) species of Trichoderma sect. Longibrachiatum into Trichoderma longibrachiatum, Trichoderma pseudokoningii, and Trichoderma reesei. The sexual species Hypocrea schweinitzii and H. jecorina were also clearly separated from each other. H. jecorina and T. reesei exhibited identical sequences, suggesting close relatedness or even species identity. Intraspecific and interspecific variation in the PCR-fingerprinting patterns supported the differentiation of species based on ITS sequences, the grouping of the strains, and the assignment of these strains to individual species. The variations between T. reesei and H. jecorina were at the same order of magnitude as found between all strains of H. jecorina, but much lower than the observed interspecific variations. Identical ITS sequences and the high similarity of PCR-fingerprinting patterns indicate a very close relationship between T. reesei and H. jecorina, whereas differences of the ITS sequences and the PCR-fingerprinting patterns show a clear phylogenetic distance between T. reesei/H. jecorina and T. longibrachiatum. T. reesei is considered to be an asexual, clonal line derived from a population of the tropical ascomycete H. jecorina. Images Fig. 2 PMID:8755548

Cytochrome P450 2D-mediated metabolism is not necessary for tafenoquine and primaquine to eradicate the erythrocytic stages of Plasmodium berghei.

PubMed

Milner, Erin E; Berman, Jonathan; Caridha, Diana; Dickson, Samuel P; Hickman, Mark; Lee, Patricia J; Marcsisin, Sean R; Read, Lisa T; Roncal, Norma; Vesely, Brian A; Xie, Lisa H; Zhang, Jing; Zhang, Ping; Li, Qigui

2016-12-07

Due to the ability of the 8-aminoquinolines (8AQs) to kill different stages of the malaria parasite, primaquine (PQ) and tafenoquine (TQ) are vital for causal prophylaxis and the eradication of erythrocytic Plasmodium sp. parasites. Recognizing the potential role of cytochrome (CYP) 450 2D6 in the metabolism and subsequent hepatic efficacy of 8-aminoquinolines, studies were designed to explore whether CYP2D-mediated metabolism was related to the ability of single-dose PQ and TQ to eliminate the asexual and sexual erythrocytic stages of Plasmodium berghei. An IV P. berghei sporozoite murine challenge model was utilized to directly compare causal prophylactic and erythrocytic activity (asexual and sexual parasite stages) dose-response relationships in C57BL/6 wild-type (WT) mice and subsequently compare the erythrocytic activity of PQ and TQ in WT and CYP2D knock-out (KO) mice. Single-dose administration of either 25 mg/kg TQ or 40 mg/kg PQ eradicated the erythrocytic stages (asexual and sexual) of P. berghei in C57BL WT and CYP2D KO mice. In WT animals, the apparent elimination of hepatic infections occurs at lower doses of PQ than are required to eliminate erythrocytic infections. In contrast, the minimally effective dose of TQ needed to achieve causal prophylaxis and to eradicate erythrocytic parasites was analogous. The genetic deletion of the CYP2D cluster does not affect the ability of PQ or TQ to eradicate the blood stages (asexual and sexual) of P. berghei after single-dose administration.

Asexual and sexual replication in sporulating organisms

NASA Astrophysics Data System (ADS)

Lee, Bohyun; Tannenbaum, Emmanuel

2007-08-01

Replication via sporulation is the replication strategy for all multicellular life, and may even be observed in unicellular life (such as with budding yeast). We consider diploid populations replicating via one of two possible sporulation mechanisms. (1) Asexual sporulation, whereby adult organisms produce single-celled diploid spores that grow into adults themselves. (2) Sexual sporulation, whereby adult organisms produce single-celled diploid spores that divide into haploid gametes. The haploid gametes enter a haploid “pool,” where they may recombine with other haploids to form a diploid spore that then grows into an adult. We consider a haploid fusion rate given by second-order reaction kinetics. We work with a simplified model where the diploid genome consists of only two chromosomes, each of which may be rendered defective with a single point mutation of the wild-type. We find that the asexual strategy is favored when the rate of spore production is high compared to the characteristic growth rate from a spore to a reproducing adult. Conversely, the sexual strategy is favored when the rate of spore production is low compared to the characteristic growth rate from a spore to a reproducing adult. As the characteristic growth time increases, or as the population density increases, the critical ratio of spore production rate to organism growth rate at which the asexual strategy overtakes the sexual one is pushed to higher values. Therefore, the results of this model suggest that, for complex multicellular organisms, sexual replication is favored at high population densities and low growth and sporulation rates.

Uniparental Inheritance Promotes Adaptive Evolution in Cytoplasmic Genomes

PubMed Central

Christie, Joshua R.; Beekman, Madeleine

2017-01-01

Eukaryotes carry numerous asexual cytoplasmic genomes (mitochondria and plastids). Lacking recombination, asexual genomes should theoretically suffer from impaired adaptive evolution. Yet, empirical evidence indicates that cytoplasmic genomes experience higher levels of adaptive evolution than predicted by theory. In this study, we use a computational model to show that the unique biology of cytoplasmic genomes—specifically their organization into host cells and their uniparental (maternal) inheritance—enable them to undergo effective adaptive evolution. Uniparental inheritance of cytoplasmic genomes decreases competition between different beneficial substitutions (clonal interference), promoting the accumulation of beneficial substitutions. Uniparental inheritance also facilitates selection against deleterious cytoplasmic substitutions, slowing Muller’s ratchet. In addition, uniparental inheritance generally reduces genetic hitchhiking of deleterious substitutions during selective sweeps. Overall, uniparental inheritance promotes adaptive evolution by increasing the level of beneficial substitutions relative to deleterious substitutions. When we assume that cytoplasmic genome inheritance is biparental, decreasing the number of genomes transmitted during gametogenesis (bottleneck) aids adaptive evolution. Nevertheless, adaptive evolution is always more efficient when inheritance is uniparental. Our findings explain empirical observations that cytoplasmic genomes—despite their asexual mode of reproduction—can readily undergo adaptive evolution. PMID:28025277

Size Matters!. Birth Size and a Size-Independent Stochastic Term Determine Asexual Reproduction Dynamics in Freshwater Planarians

NASA Astrophysics Data System (ADS)

Thomas, Michael A.; Quinodoz, Sofia; Schötz, Eva-Maria

2012-09-01

Asexual reproduction by division in higher organisms is rare, because a prerequisite is the ability to regenerate an entire organism from a piece of the original body. Freshwater planarians are one of the few animals that can reproduce this way, but little is known about the regulation of their reproduction cycles or strategies. We have previously shown that a planarian's reproduction strategy is randomized to include fragmentations, producing multiple offspring, as well as binary fissions, and can be partially explained by a maximum relative entropy principle. In this study we attempt to decompose the factors controlling their reproduction cycle. Based on recent studies on the cell cycle of budding yeast, which suggest that molecular noise in gene expression and cell size at birth together control cell cycle variability, we investigated whether the variability in planarian reproduction waiting times could be similarly regulated. We find that such a model can indeed explain the observed distribution of waiting times between birth and next reproductive event, suggesting that birth size and a stochastic noise term govern the reproduction dynamics of asexual planarians.

Life-Span Extension by Caloric Restriction Is Determined by Type and Level of Food Reduction and by Reproductive Mode in Brachionus manjavacas (Rotifera)

PubMed Central

2013-01-01

We measured life span and fecundity of three reproductive modes in a clone of the monogonont rotifer Brachionus manjavacas subjected to chronic caloric restriction (CCR) over a range of food concentrations or to intermittent fasting (IF). IF increased life span 50%–70% for all three modes, whereas CCR increased life span of asexual females derived from sexually or asexually produced eggs, but not that of sexual females. The main effect of CR on both asexual modes was to delay death at young ages, rather than to prevent death at middle ages or to greatly extend maximum life span; in contrast CR in sexual females greatly increased the life span of a few long-lived individuals. Lifetime fecundity did not decrease with CCR, suggesting a lack of resource allocation trade-off between somatic maintenance and reproduction. Multiple outcomes for a clonal lineage indicate that different responses are established through epigenetic programming, whereas differences in life-span allocations suggest that multiple genetic mechanisms mediate life-span extension. PMID:22904096

Geographic parthenogenesis in a consumer-resource model for sexual reproduction.

PubMed

Song, Yixian; Scheu, Stefan; Drossel, Barbara

2011-03-21

The phenomenon of geographic parthenogenesis is closely tied to the question of why sexual reproduction is the dominant mode of reproduction in animals and plants. Geographic parthenogenesis describes the fact that many species reproduce asexually at the boundaries of their range. We present a mathematical model that derives the dominance of sexuals at the center and the dominance of asexuals at the boundary of a species' range from exactly the same mechanism. Our model is based on a set of resources that regrow slowly and that can be consumed only by those individuals that have a suitable genotype. Genotype is implemented by a multilocus model with two alleles at each locus, and with free recombination during production of sexual offspring. The model is tailored to seasonal species with intermittent mixis and low survival of offspring, such as Daphnia and aphids. Several patches of resources are arranged in a row, with a gradient of those parameters that typically vary through the range of species. By letting sexually and asexually reproducing populations compete, we obtain the typical patterns of geographic parthenogenesis. Copyright © 2010 Elsevier Ltd. All rights reserved.

Fungal spore germination into yeast or mycelium: possible implications of dimorphism in evolution and human pathogenesis

NASA Astrophysics Data System (ADS)

Ghormade, Vandana; Deshpande, M. V.

The ability of dimorphism in fungi is conventionally regarded as a reversible change between the two vegetative forms, yeast and mycelium, in response to environmental change. A zygomycetous isolate, Benjaminiella poitrasii, exhibited yeast-mycelium transition in response to the change in temperature (37-28 °C) and decrease in glucose concentration. For the first time the presence of dimorphic response during asexual and sexual spore germination is reported under the dimorphism-triggering conditions in B. poitrasii. The zygospores germinated into budding yeast when subjected to yeast-form supporting conditions. The mycelium-form favoring conditions gave rise to true mycelium. Similarly, the asexual spores displayed a dimorphic response during germination. Our observations suggest that dimorphism is an intrinsic ability present in the vegetative, asexual, and sexual forms of the fungus. As dimorphic fungi are intermediate to the unicellular yeast and the filamentous forms, understanding of the dimorphic character could be useful to trace the evolutionary relationships among taxonomically different fungi. Moreover, the implications of spore germination during the onset of pathogenesis and in drug development for human health care are discussed.

Life-span extension by caloric restriction is determined by type and level of food reduction and by reproductive mode in Brachionus manjavacas (Rotifera).

PubMed

Gribble, Kristin E; Welch, David B Mark

2013-04-01

We measured life span and fecundity of three reproductive modes in a clone of the monogonont rotifer Brachionus manjavacas subjected to chronic caloric restriction (CCR) over a range of food concentrations or to intermittent fasting (IF). IF increased life span 50%-70% for all three modes, whereas CCR increased life span of asexual females derived from sexually or asexually produced eggs, but not that of sexual females. The main effect of CR on both asexual modes was to delay death at young ages, rather than to prevent death at middle ages or to greatly extend maximum life span; in contrast CR in sexual females greatly increased the life span of a few long-lived individuals. Lifetime fecundity did not decrease with CCR, suggesting a lack of resource allocation trade-off between somatic maintenance and reproduction. Multiple outcomes for a clonal lineage indicate that different responses are established through epigenetic programming, whereas differences in life-span allocations suggest that multiple genetic mechanisms mediate life-span extension.

Gluten sensitivity in patients with IgA nephropathy.

PubMed

Smerud, Hilde Kloster; Fellström, Bengt; Hällgren, Roger; Osagie, Sonia; Venge, Per; Kristjánsson, Gudjón

2009-08-01

Coeliac disease is more frequent in IgA nephropathy (IgAN) patients compared to the healthy population. Several hypotheses postulate that food antigens like gluten may be involved in the onset of IgAN. In this study, we used a recently developed mucosal patch technique to evaluate the rectal mucosal inflammatory reaction to gluten in patients with IgAN (n = 27) compared to healthy subjects (n = 18). The rectal mucosal production of nitric oxide (NO) and release of myeloperoxidase (MPO) and eosinophil cationic protein (ECP) were measured. Serum samples were analysed for IgA and IgG antigliadin antibodies (AGA), IgA antibodies against tissue transglutaminase and IgA endomysium antibodies. Gluten reactivity, defined as increase in MPO and/or NO after gluten exposure, was observed in 8 of 27 IgAN patients. The prevalence of HLA-DQ2 and DQ8 was not increased among gluten-sensitive patients, and the total prevalence among IgAN patients was the same as for the normal population. An elevated serum IgA AGA response was seen in 9 of 27 IgAN patients. The increase in IgA AGA did not correlate with the gluten sensitivity as measured by NO and/or MPO. A specific serum IgG AGA response was seen in one patient only. Antibodies against tissue transglutaminase and endomysium were not observed. It is concluded that approximately one-third of our IgAN patients have a rectal mucosal sensitivity to gluten, but without signs of coeliac disease, and we hypothesize that such sub-clinical inflammation to gluten might be involved in the pathogenesis of IgAN in a subgroup of patients.

Similar response patterns to topical minoxidil foam 5% in frontal and vertex scalp of men with androgenetic alopecia: a microarray analysis.

PubMed

Mirmirani, P; Consolo, M; Oyetakin-White, P; Baron, E; Leahy, P; Karnik, P

2015-06-01

There are regional variations in the scalp hair miniaturization seen in androgenetic alopecia (AGA). Use of topical minoxidil can lead to reversal of miniaturization in the vertex scalp. However, its effects on other scalp regions have been less well studied. To determine whether scalp biopsies from men with AGA show variable gene expression before and after 8 weeks of treatment with minoxidil topical foam 5% (MTF) vs. placebo. A placebo-controlled double-blinded prospective pilot study of MTF vs. placebo was conducted in 16 healthy men aged 18-49 years with Hamilton-Norwood type IV-V thinning. The subjects were asked to apply the treatment (active drug or placebo) to the scalp twice daily for 8 weeks. Stereotactic scalp photographs were taken at the baseline and final visits, to monitor global hair growth. Scalp biopsies were taken at the leading edge of hair loss from the frontal and vertex scalp before and after treatment with MTF and placebo, and microarray analysis was performed using the Affymetrix GeneChip HG U133 Plus 2.0. Global stereotactic photographs showed that MTF induced hair growth in both the frontal and vertex scalp of patients with AGA. Regional differences in gene expression profiles were observed before treatment. However, MTF treatment induced the expression of hair keratin-associated genes and decreased the expression of epidermal differentiation complex and inflammatory genes in both scalp regions. These data suggest that MTF is effective in the treatment of both the frontal and vertex scalp of patients with AGA. © 2014 British Association of Dermatologists.

Prevalence of dermatologic manifestations and metabolic biomarkers in women with polycystic ovary syndrome in north China.

PubMed

Feng, Jin-Ge; Guo, Yan; Ma, Li-Ang; Xing, Jin; Sun, Rui-Feng; Zhu, Wei

2018-06-01

Cutaneous features of hyperandrogenism in polycystic ovary syndrome (PCOS) include acne, hirsutism, seborrhea, androgenic alopecia (AGA), and acanthosis nigricans (AN). However, the relationships have not been well known broadly in terms of clinical hyperandrogenism and biochemical markers. The aim of this study was to investigate biochemical and metabolic parameters in relation to cutaneous characters women in with and without PCOS. This was a cross-sectional retrospective study including 186 women with PCOS and 113 age-matched without PCOS women. Acne grade, hirsutism, seborrhea, AGA, and AN were recorded. Hormonal and metabolic parameters were measured. The most common finding was acne, and AN was the least dermatological manifestations between PCOS and non-PCOS groups. The severity location and type of acne did not differ in PCOS women compared to non-PCOS women. Significant differences were found with respect to free androgen index (FAI) (P = .036), sex hormone-binding globulin (SHBG) (P = .023), and body mass index (BMI) (P = .001) between PCOS with acne and PCOS without acne groups. Overall, age (P = .005) was significantly decreased, while BMI (P = .004) was significantly higher in PCOS with hirsutism. The mean serum total testosterone (TT), dehydroepiandrosterone sulfate, and FAI were significantly elevated, but SHBG was decreased between PCOS with and without hirsutism groups. There were significantly different BMI (P = .018) and triglyceride (P = .024) except other hormonal parameter of without AGA group. This study indicated a strong correlation between hirsutism and metabolic abnormalities. Hirsutism is the most common cutaneous finding in PCOS women. Acne and AGA are associated with other manifestations of clinical hyperandrogenism, but not obvious markers of biochemical hyperandrogenemia and metabolic dysfunction. © 2017 Wiley Periodicals, Inc.

Circulating osteoprotegerin and sRANKL concentrations in the perinatal period at term. The impact of intrauterine growth restriction.

PubMed

Briana, Despina D; Boutsikou, Maria; Baka, Stavroula; Hassiakos, Demetrios; Gourgiotis, Demetrios; Malamitsi-Puchner, Ariadne

2009-01-01

Intrauterine growth restriction (IUGR) has been associated with low bone mass in infancy and increased risk for osteoporosis development in adult life. Osteoprotegerin (OPG) and receptor activator of nuclear factor-kappaB ligand (RANKL) are main determinants of bone resorption. To investigate OPG and soluble RANKL (sRANKL) concentrations in maternal, fetal and neonatal serum of IUGR patients and appropriate for gestational age (AGA) pregnancies. Additionally, plasma intact parathormone (PTH) concentrations were evaluated. Circulating OPG, sRANKL and PTH concentrations were measured in 40 mothers and their singleton full-term fetuses-neonates (AGA: n = 20, and IUGR: n =20) on postnatal days 1 (N1) and 4 (N4). No significant differences in OPG, sRANKL or PTH concentrations were observed between AGA and IUGR groups. In both groups, maternal OPG concentrations were elevated compared with fetal, and N1 and N4 concentrations (p < or = 0.045 in all cases). N4 sRANKL concentrations were elevated compared with maternal, fetal and N1 ones (p < or = 0.01 in all cases). Fetal and N1 sRANKL concentrations correlated positively with PTH levels (r = 0.642, p = 0.024 and r = 0.584, p = 0.046, respectively). The lack of a difference in circulating OPG, sRANKL or PTH concentrations between IUGR cases and AGA controls suggests that the low bone mass of IUGR infants may not be related to higher bone resorption rates. The increased maternal, compared with fetal/neonatal, OPG concentrations may suggest their placental origin. The lower OPG and higher sRANKL concentrations in fetuses and neonates could represent high bone resorption rates. Copyright 2009 S. Karger AG, Basel.

The effects of silver ions on copper metabolism in rats.

PubMed

Ilyechova, E Yu; Saveliev, A N; Skvortsov, A N; Babich, P S; Zatulovskaia, Yu A; Pliss, M G; Korzhevskii, D E; Tsymbalenko, N V; Puchkova, L V

2014-10-01

The influence of short and prolonged diet containing silver ions (Ag-diet) on copper metabolism was studied. Two groups of animals were used: one group of adult rats received a Ag-diet for one month (Ag-A1) and another group received a Ag-diet for 6 months from birth (Ag-N6). In Ag-A1 rats, the Ag-diet caused a dramatic decrease of copper status indexes that was manifested as ceruloplasmin-associated copper deficiency. In Ag-N6 rats, copper status indexes decreased only 2-fold as compared to control rats. In rats of both groups, silver entered the bloodstream and accumulated in the liver. Silver was incorporated into ceruloplasmin (Cp), but not SOD1. In the liver, a prolonged Ag-diet caused a decrease of the expression level of genes, associated with copper metabolism. Comparative spectrophotometric analysis of partially purified Cp fractions has shown that Cp from Ag-N6 rats was closer to holo-Cp by specific enzymatic activities and tertiary structure than Cp from Ag-A1 rats. However, Cp of Ag-N6 differs from control holo-Cp and Cp of Ag-A1 in its affinity to DEAE-Sepharose and in its binding properties to lectins. In the bloodstream of Ag-N6, two Cp forms are present as shown in pulse-experiments on rats with the liver isolated from circulation. One of the Cp isoforms is of hepatic origin, and the other is of extrahepatic origin; the latter is characterized by a faster rate of secretion than hepatic Cp. These data allowed us to suggest that the disturbance of holo-Cp formation in the liver was compensated by induction of extrahepatic Cp synthesis. The possible biological importance of these effects is discussed.

Application of a global reference for fetal-weight and birthweight percentiles in predicting infant mortality.

PubMed

Ding, G; Tian, Y; Zhang, Y; Pang, Y; Zhang, J S; Zhang, J

2013-12-01

To determine whether the recently published A global reference for fetal-weight and birthweight percentiles (Global Reference) improves small- (SGA), appropriate- (AGA), and large-for-gestational-age (LGA) definitions in predicting infant mortality. Population-based cohort study. The US Linked Livebirth and Infant Death records between 1995 and 2004. Singleton births with birthweight >500 g born at 24-41 weeks of gestation. We compared infant mortality rates of SGA, AGA, and LGA infants classified by three different references: the Global Reference; a commonly used birthweight reference; and Hadlock's ultrasound reference. Infant mortality rates. Among 33 997 719 eligible liveborn singleton births, 25% of preterm and 9% of term infants were classified differently for SGA, AGA, and LGA by the Global Reference and the birthweight reference. The Global Reference indicated higher mortality rates in preterm SGA and preterm LGA infants than the birthweight reference. The mortality rate was considerably higher in infants classified as preterm SGA by the Global Reference but not by the birthweight reference, compared with the corresponding infants classified by the birthweight reference but not by the Global Reference (105.7 versus 12.9 per 1000, RR 8.17, 95% CI 7.38-9.06). Yet, the differences in mortality rates were much smaller in term infants than in preterm infants. Black infants had a particularly higher mortality rate than other races in AGA and LGA preterm and term infants. In respect to the commonly used birthweight reference, the Global Reference increases the identification of infant deaths by improved classification of abnormal newborn size at birth, and these advantages were more obvious in preterm than in term infants. © 2013 RCOG.

Efficacy and safety of a new 5% minoxidil formulation in male androgenetic alopecia: A randomized, placebo-controlled, double-blind, noninferiority study.

PubMed

Blume-Peytavi, Ulrike; Issiakhem, Zahida; Gautier, Stephanie; Kottner, Jan; Wigger-Alberti, Walter; Fischer, Tobias; Hoffmann, Rolf; Tonner, Françoise; Bouroubi, Athmane; Voisard, Jean-Jacques

2018-04-16

Androgenetic alopecia (AGA) is the most common cause of hair loss in men. Topical minoxidil solutions can help to treat AGA but have to be applied continuously to be effective. A new minoxidil formulation with improved cosmetic characteristics (DC0120, Pierre-Fabre Dermatologie) was tested for noninferiority vs a comparator minoxidil product (ALOSTIL ® , Johnson & Johnson) in stimulating hair growth in men with AGA. Two 10 cm 2 areas on the scalp of each subject were randomized to receive DC0120, the comparator, or one of their corresponding vehicles, applied twice per day for 16 weeks. Nonvellus target area hair count (TAHC) was measured within treatment areas at baseline (day 1) and after 8 and 16 weeks by digital phototrichogram. Two hundred and twenty subjects were included and randomized, of which 210 completed the study. The mean change in nonvellus TAHC between baseline and week 16 was +22.0 hairs/cm 2 (95% CI: 18.1; 25.9) in the DC0120 group and +20.5 hairs/cm 2 (95% CI: 16.6; 24.4) in the comparator group. The adjusted mean difference in TAHC changes between the two treatments was +1.5 hairs/cm 2 (95% CI -2.3; 5.2), with the lower 95% confidence interval above the noninferiority threshold of -7 hairs/cm 2 . This indicated that DC0120 was noninferior to the comparator. Both minoxidil treatments also increased nonvellus TAHC compared to vehicle groups at 8 and 16 weeks. No new safety signals were observed. DC0120 was as safe and effective as a similar marketed minoxidil product for stimulating hair growth in men with AGA. © 2018 Wiley Periodicals, Inc.

A Comparative Study of Microneedling with Platelet-rich Plasma Plus Topical Minoxidil (5%) and Topical Minoxidil (5%) Alone in Androgenetic Alopecia.

PubMed

Shah, Kaksha B; Shah, Aarti N; Solanki, Rekha B; Raval, Ranjan C

2017-01-01

There are very few studies evaluating efficacy of platelet-rich plasma (PRP) in hair restoration and its combination with microneedling. As far as ascertained, there is no study to evaluate efficacy of microneedling with PRP plus topical minoxidil (5%) versus topical minoxidil (5%) alone in androgenetic alopecia (AGA). This study aims (1) to compare the efficacy of (a) topical minoxidil (5%) alone and (b) topical minoxidil (5%) + microneedling with PRP in men between 18 and 50 years with AGA Grade III to V vertex (Norwood-Hamilton scale) and (2) to perform objective and subjective evaluation based on clinical improvement and photographic evidence. The study was conducted in the outpatient department of dermatology, venereology, and leprology in tertiary care hospital. It was open, prospective study. Fifty patients with AGA were selected on the basis of inclusion and exclusion criteria. These patients were randomly divided into two groups of 25 patients each and were given following treatment: (i) Group A: topical minoxidil (5%) alone and (ii) Group B: topical minoxidil (5%) + microneedling with platelet-rich plasma (PRP). Patients were assessed before starting the treatment and at the end of 6 months on the basis of (a) Patient's self-assessment based on standardized seven-point scale compared with baseline (b) Physician's assessment based on standardized seven-point scale of hair growth compared with baseline. There was a significant improvement ( P < 0.05) in both patients' assessment and investigator's assessment in Group B as compared to Group A at the end of 6 months. Microneedling with PRP is safe, effective, and a promising tool for the management of AGA.

Prenatal and post-natal cost of small for gestational age infants: a national study.

PubMed

Marzouk, Alicia; Filipovic-Pierucci, Antoine; Baud, Olivier; Tsatsaris, Vassilis; Ego, Anne; Charles, Marie-Aline; Goffinet, François; Evain-Brion, Danièle; Durand-Zaleski, Isabelle

2017-03-21

Small for gestational age (SGA) infants are at increased risk for preterm birth morbidities as well as a range of adverse perinatal outcomes that result in part from associated premature birth. We sought to evaluate the costs of SGA versus appropriate for gestational age (AGA) infants in France from pregnancy through the first year of life and separate the contributions of prematurity from the contribution of foetal growth on costs. This is a cross-sectional population-based study using national hospital discharge data from French public and private hospitals. SGA infants were defined as newborns with a birth weight below the 10th percentile of French intrauterine growth curves adjusted for foetal sex. AGA infants were defined as newborns with a birth weight between the 25th and the 75th. All births were selected between January 1st, 2011 and December 31st, 2011. Costs were calculated from the hospital perspective for both mothers and children using their diagnostic related group and the French national cost study. Hospital outcomes were extracted from the database and compared by gestational age and mode of delivery. Of 777,720 total births in 2011, 84,688 SGA births (10.9%) and 395,760 AGA births (50.8%) were identified. After adjustment for gestational age, the cost for an SGA infant was €2,783 higher than for an AGA infant. The total maternal and infant hospital cost of SGA in France was estimated at 23% the total cost for deliveries. The high cost is explained by higher complication rates, more frequent hospital readmissions and longer lengths of stay. Being small for gestational age is an independent contributor to 1-year hospital costs for both mothers and infants.

Identifying a parsimonious model for predicting academic achievement in undergraduate medical education: A confirmatory factor analysis

PubMed Central

Ali, Syeda Kauser; Baig, Lubna Ansari; Violato, Claudio; Zahid, Onaiza

2017-01-01

Objectives: This study was conducted to adduce evidence of validity for admissions tests and processes and for identifying a parsimonious model that predicts students’ academic achievement in Medical College. Methods: Psychometric study done on admission data and assessment scores for five years of medical studies at Aga Khan University Medical College, Pakistan using confirmatory factor analysis (CFA) and structured equation modeling (SEM). Sample included 276 medical students admitted in 2003, 2004 and 2005. Results: The SEM supported the existence of covariance between verbal reasoning, science and clinical knowledge for predicting achievement in medical school employing Maximum Likelihood (ML) estimations (n=112). Fit indices: χ2 (21) = 59.70, p =<.0001; CFI=.873; RMSEA = 0.129; SRMR = 0.093. Conclusions: This study shows that in addition to biology and chemistry which have been traditionally used as major criteria for admission to medical colleges in Pakistan; mathematics has proven to be a better predictor for higher achievements in medical college. PMID:29067063

Identifying a parsimonious model for predicting academic achievement in undergraduate medical education: A confirmatory factor analysis.

PubMed

Ali, Syeda Kauser; Baig, Lubna Ansari; Violato, Claudio; Zahid, Onaiza

2017-01-01

This study was conducted to adduce evidence of validity for admissions tests and processes and for identifying a parsimonious model that predicts students' academic achievement in Medical College. Psychometric study done on admission data and assessment scores for five years of medical studies at Aga Khan University Medical College, Pakistan using confirmatory factor analysis (CFA) and structured equation modeling (SEM). Sample included 276 medical students admitted in 2003, 2004 and 2005. The SEM supported the existence of covariance between verbal reasoning, science and clinical knowledge for predicting achievement in medical school employing Maximum Likelihood (ML) estimations (n=112). Fit indices: χ 2 (21) = 59.70, p =<.0001; CFI=.873; RMSEA = 0.129; SRMR = 0.093. This study shows that in addition to biology and chemistry which have been traditionally used as major criteria for admission to medical colleges in Pakistan; mathematics has proven to be a better predictor for higher achievements in medical college.

Candidate Insect Repellent AI3-35713-aGa N-Pentylvaleramide

DTIC Science & Technology

1976-10-19

0 Io -44 0 0 ON . w *0. 4) L0 0 ~ -- 0t, M- N 41 M , y ) *4Ur 0 f E0 4) MN 4) O.* r U 4J404 Ul~ r, eo 0 r. a.O~U f- n AN 1. ) 41$44 r. 4 0 -. ) MJ N ...TOPICAL HAZARD EVALUATION . , OF CANDIDATE INSECT REPELLENT AI3-35713-aGa N -PENTYLVALERAMIDE STUDY NO. 51-0802-77 AUGUST 1975 - AUGUST 1976 Approved...CLASSIFICATION DO’ THIS PAGE (Wlhet Der. Znftro* REPORT DOCUMENTATION PAGE EA~D N RM 1. REPORT NUMBER 2. GOVT ACCESSION No. 3. RECIPIENT’S CATALOG NUMBER 51

Age-Related DNA Methylation Changes and Neoplastic Transformation of the Human Prostate

DTIC Science & Technology

2011-07-01

Vol. 4 Issue 1 Figure 4. Methylation and expression analysis of the Sprouty1. (A) Representative program traces for Sprouty1. Gray colums represents...5’-ggt acc CCC TCC TGA GCT CAT GGT AAC CT-3’ Fwd 6 (-509) 5’-ggt acc CTT CTG GTT TGG AGC ACA GTG CAA AG-3’ Fwd 5 (-1318) 5’ggt acc AGA AGA CCT...CCC GAG GTG GAT GTT A-3’ Fwd3 (-2025) 5’-ggt acc CTG TCA ATC ACC GGG AGC-3’ Reverse (+8) 5’-gct agc AAT CCG CAC TGA ATA AAT AGT TGA C-3’. For

Improving genetic immobilization of a cellulase on yeast cell surface for bioethanol production using cellulose.

PubMed

Yang, Jinying; Dang, Hongyue; Lu, Jian Ren

2013-04-01

In this study, Saccharomyces cerevisiae was genetically engineered to harbor the capability of utilizing celluloses for bioethanol production by displaying active cellulolytic enzymes on the cell surface. An endo-1,4-β-glucanase gene egX was cloned from Bacillus pumilus C-9 and its expression products, the EGX cellulases, were displayed on the cell surface of S. cerevisiae by fusing egX with aga2 that encodes the binding subunit of the S. cerevisiae cell wall protein α-agglutinin. To achieve high gene copies and stability, multicopy integration was obtained by integrating the fusion aga2-egX gene into the rDNA region of the S. cerevisiae chromosome. To achieve high expression and surface display efficiency, the aga2-egX gene was expressed under the control of a strong promoter. The presence of the enzymatically active cellulase fusion proteins on the S. cerevisiae cell surface was verified by carboxymethyl cellulase activity assay and immunofluorescence microscopy. This work presented a promising strategy to genetically engineer yeasts to perform efficient fermentation of cellulosic materials for bioethanol production. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Identifying nutrient sources to three lagoons at Ofu and Olosega, American Samoa using δ15N of benthic macroalgae

USGS Publications Warehouse

Garrison, Virginia H.; Kroeger, Kevin D.; Fenner, Douglas; Craig, Peter

2007-01-01

Degradation of nearshore habitats is a serious problem in some areas of American Samoa, such as in Pago Pago Harbor on Tutuila Island, and is a smaller but chronic problem in other areas. Sedimentation, pollution, nutrient enrichment from surface runoff or groundwater, and trampling are the major factors causing the changes (Peshut and Brooks, 2005). On the outer islands of Ofu and Olosega (Manu’a Islands; Fig. 1), there is an interesting contrast between relatively pristine lagoon habitats not far from comparatively degraded lagoon habitats. To’aga lagoon on the southeast side of Ofu Island (Fig. 1) has clear waters, a high diversity of corals and fishes, no human habitations, and an undeveloped watershed with no streams. To’aga lagoon is within the boundaries of the National Park of American Samoa and is the site of long-term research on coral reef resilience and global climate change. Only 3 km to the east of To’aga is a degraded lagoon that fronts Olosega Village. The Olosega lagoon is similar in size but has significantly less live coral than To’aga, and blooms of filamentous algae have been reported to cover the Olosega lagoon/reef flat bottom (unpublished data, PC; Fig. 2). The islands are influenced by the same regional-scale and biogeochemical regimes, and both islands are remnants of a volcanic caldera (Craig, 2005). Thus, local factors operating on the scale of a kilometer or less are thought to be driving the differences observed between lagoons. Land disturbance is limited to a road linking the villages, the clearing of vegetation for buildings, and two village dump sites located on the narrow strip of land between the steep slopes of the islands and the shoreline; there is no industry or associated pollution on either island. Cesspools are used for sewage disposal. Nutrient enrichment (from cesspools) of groundwater and the lagoon, as well as trampling during gleaning of reef organisms, are possible factors affecting the spatial relief and benthic composition of the lagoons. A pristine lagoon site (To’aga) and two that may be influenced by adjacent human populations (Ofu and Olosega Villages) were selected for study.

Gut barrier failure biomarkers are associated with poor disease outcome in patients with primary sclerosing cholangitis

PubMed Central

Tornai, Tamas; Palyu, Eszter; Vitalis, Zsuzsanna; Tornai, Istvan; Tornai, David; Antal-Szalmas, Peter; Norman, Gary L; Shums, Zakera; Veres, Gabor; Dezsofi, Antal; Par, Gabriella; Par, Alajos; Orosz, Peter; Szalay, Ferenc; Lakatos, Peter Laszlo; Papp, Maria

2017-01-01

AIM To assess the prevalence of a panel of serologic markers that reflect gut barrier dysfunction in a mixed cohort of pediatric and adult primary sclerosing cholangitis (PSC) patients. METHODS Sera of 67 PSC patients [median age (range): 32 (5-79) years, concomitant IBD: 67% and cirrhosis: 20%] were assayed for the presence of antibodies against to F-actin (AAA IgA/IgG) and gliadin (AGA IgA/IgG)] and for serum level of intestinal fatty acid-binding protein (I-FABP) by ELISA. Markers of lipopolysaccharide (LPS) exposure [LPS binding protein (LBP)] and various anti-microbial antibodies [anti-OMP Plus IgA and endotoxin core IgA antibody (EndoCAb)] were also determined. Poor disease outcome was defined as orthotopic liver transplantation and/or liver-related death during the follow-up [median: 99 (14-106) mo]. One hundred and fifty-three healthy subjects (HCONT) and 172 ulcerative colitis (UC) patients were the controls. RESULTS A total of 28.4%, 28.0%, 9% and 20.9% of PSC patients were positive for AAA IgA, AAA IgG, AGA IgA and AGA IgG, respectively. Frequencies of AAA IgA and AAA IgG (P < 0.001, for both) and AGA IgG (P = 0.01, for both) but not AGA IgA were significantly higher compared to both of the HCONT and the UC groups. In survival analysis, AAA IgA-positivity was revealed as an independent predictor of poor disease outcome after adjusting either for the presence of cirrhosis [HR = 5.15 (1.27-20.86), P = 0.022 or for the Mayo risk score (HR = 4.24 (0.99-18.21), P = 0.052]. AAA IgA-positivity was significantly associated with higher frequency of anti-microbial antibodies (P < 0.001 for EndoCab IgA and P = 0.012 for anti-OMP Plus IgA) and higher level of the enterocyte damage marker (median I-FABPAAA IgA pos vs neg: 365 vs 166 pg/mL, P = 0.011), but not with serum LBP level. CONCLUSION Presence of IgA type AAA identified PSC patients with progressive disease. Moreover, it is associated with enhanced mucosal immune response to various microbial antigens and enterocyte damage further highlighting the importance of the gut-liver interaction in PSC. PMID:28839442

Stress and sex in malaria parasites: Why does commitment vary?

PubMed

Carter, Lucy M; Kafsack, Björn F C; Llinás, Manuel; Mideo, Nicole; Pollitt, Laura C; Reece, Sarah E

2013-01-01

For vector-borne parasites such as malaria, how within- and between-host processes interact to shape transmission is poorly understood. In the host, malaria parasites replicate asexually but for transmission to occur, specialized sexual stages (gametocytes) must be produced. Despite the central role that gametocytes play in disease transmission, explanations of why parasites adjust gametocyte production in response to in-host factors remain controversial. We propose that evolutionary theory developed to explain variation in reproductive effort in multicellular organisms, provides a framework to understand gametocyte investment strategies. We examine why parasites adjust investment in gametocytes according to the impact of changing conditions on their in-host survival. We then outline experiments required to determine whether plasticity in gametocyte investment enables parasites to maintain fitness in a variable environment. Gametocytes are a target for anti-malarial transmission-blocking interventions so understanding plasticity in investment is central to maximizing the success of control measures in the face of parasite evolution.

Characterizing Phase Transitions in a Model of Neutral Evolutionary Dynamics

NASA Astrophysics Data System (ADS)

Scott, Adam; King, Dawn; Bahar, Sonya

2013-03-01

An evolutionary model was recently introduced for sympatric, phenotypic evolution over a variable fitness landscape with assortative mating (Dees & Bahar 2010). Organisms in the model are described by coordinates in a two-dimensional phenotype space, born at random coordinates with limited variation from their parents as determined by a mutation parameter, mutability. The model has been extended to include both neutral evolution and asexual reproduction in Scott et al (submitted). It has been demonstrated that a second order, non-equilibrium phase transition occurs for the temporal dynamics as the mutability is varied, for both the original model and for neutral conditions. This transition likely belongs to the directed percolation universality class. In contrast, the spatial dynamics of the model shows characteristics of an ordinary percolation phase transition. Here, we characterize the phase transitions exhibited by this model by determining critical exponents for the relaxation times, characteristic lengths, and cluster (species) mass distributions. Missouri Research Board; J.S. McDonnell Foundation

A Genome-wide CRISPR Screen in Toxoplasma Identifies Essential Apicomplexan Genes.

PubMed

Sidik, Saima M; Huet, Diego; Ganesan, Suresh M; Huynh, My-Hang; Wang, Tim; Nasamu, Armiyaw S; Thiru, Prathapan; Saeij, Jeroen P J; Carruthers, Vern B; Niles, Jacquin C; Lourido, Sebastian

2016-09-08

Apicomplexan parasites are leading causes of human and livestock diseases such as malaria and toxoplasmosis, yet most of their genes remain uncharacterized. Here, we present the first genome-wide genetic screen of an apicomplexan. We adapted CRISPR/Cas9 to assess the contribution of each gene from the parasite Toxoplasma gondii during infection of human fibroblasts. Our analysis defines ∼200 previously uncharacterized, fitness-conferring genes unique to the phylum, from which 16 were investigated, revealing essential functions during infection of human cells. Secondary screens identify as an invasion factor the claudin-like apicomplexan microneme protein (CLAMP), which resembles mammalian tight-junction proteins and localizes to secretory organelles, making it critical to the initiation of infection. CLAMP is present throughout sequenced apicomplexan genomes and is essential during the asexual stages of the malaria parasite Plasmodium falciparum. These results provide broad-based functional information on T. gondii genes and will facilitate future approaches to expand the horizon of antiparasitic interventions. Copyright © 2016 Elsevier Inc. All rights reserved.

The Putative Protein Methyltransferase LAE1 of Trichoderma atroviride Is a Key Regulator of Asexual Development and Mycoparasitism

PubMed Central

Aghcheh, Razieh Karimi; Druzhinina, Irina S.; Kubicek, Christian P.

2013-01-01

In Ascomycota the protein methyltransferase LaeA is a global regulator that affects the expression of secondary metabolite gene clusters, and controls sexual and asexual development. The common mycoparasitic fungus Trichoderma atroviride is one of the most widely studied agents of biological control of plant-pathogenic fungi that also serves as a model for the research on regulation of asexual sporulation (conidiation) by environmental stimuli such as light and/or mechanical injury. In order to learn the possible involvement of LAE1 in these two traits, we assessed the effect of deletion and overexpression of lae1 gene on conidiation and mycoparasitic interaction. In the presence of light, conidiation was 50% decreased in a Δ lae1 and 30–50% increased in lae1-overexpressing (OElae1) strains. In darkness, Δ lae1 strains did not sporulate, and the OElae1 strains produced as much spores as the parent strain. Loss-of-function of lae1 also abolished sporulation triggered by mechanical injury of the mycelia. Deletion of lae1 also increased the sensitivity of T. atroviride to oxidative stress, abolished its ability to defend against other fungi and led to a loss of mycoparasitic behaviour, whereas the OElae1 strains displayed enhanced mycoparasitic vigor. The loss of mycoparasitic activity in the Δ lae1 strain correlated with a significant underexpressionn of several genes normally upregulated during mycoparasitic interaction (proteases, GH16 ß-glucanases, polyketide synthases and small cystein-rich secreted proteins), which in turn was reflected in the partial reduction of formation of fungicidal water soluble metabolites and volatile compounds. Our study shows T. atroviride LAE1 is essential for asexual reproduction in the dark and for defense and parasitism on other fungi. PMID:23826217

Planarian D-amino acid oxidase is involved in ovarian development during sexual induction.

PubMed

Maezawa, Takanobu; Tanaka, Hiroyuki; Nakagawa, Haruka; Ono, Mizuki; Aoki, Manabu; Matsumoto, Midori; Ishida, Tetsuo; Horiike, Kihachiro; Kobayashi, Kazuya

2014-05-01

To elucidate the molecular mechanisms underlying switching from asexual to sexual reproduction, namely sexual induction, we developed an assay system for sexual induction in the hermaphroditic planarian species Dugesia ryukyuensis. Ovarian development is the initial and essential step in sexual induction, and it is followed by the formation of other reproductive organs, including the testes. Here, we report a function of a planarian D-amino acid oxidase, Dr-DAO, in the control of ovarian development in planarians. Asexual worms showed significantly more widespread expression of Dr-DAO in the parenchymal space than did sexual worms. Inhibition of Dr-DAO by RNAi caused the formation of immature ovaries. In addition, we found that feeding asexual worms 5 specific D-amino acids could induce the formation of immature ovaries that are similar to those observed in Dr-DAO knockdown worms, suggesting that Dr-DAO inhibits the formation of immature ovaries by degrading these D-amino acids. Following sexual induction, Dr-DAO expression was observed in the ovaries. The knockdown of Dr-DAO during sexual induction delayed the maturation of the other reproductive organs, as well as ovary. These findings suggest that Dr-DAO acts to promote ovarian maturation and that complete sexual induction depends on the production of mature ovaries. We propose that Dr-DAO produced in somatic cells prevents the onset of sexual induction in the asexual state, and then after sexual induction, the female germ cells specifically produce Dr-DAO to induce full maturation. Therefore, Dr-DAO produced in somatic and female germline cells may play different roles in sexual induction. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Identification of genes associated with asexual reproduction in Phyllosticta citricarpa mutants obtained through Agrobacterium tumefaciens transformation.

PubMed

Goulin, Eduardo Henrique; Savi, Daiani Cristina; Petters, Desirrê Alexia Lourenço; Kava, Vanessa; Galli-Terasawa, Lygia; Silva, Geraldo José; Glienke, Chirlei

2016-11-01

Phyllosticta citricarpa is the epidemiological agent of Citrus Black Spot (CBS) disease, which is responsible for large economic losses worldwide. CBS is characterized by the presence of spores (pycnidiospores) in dark lesions of fruit, which are also responsible for short distance dispersal of the disease. The identification of genes involved in asexual reproduction of P. citricarpa can be an alternative for directional disease control. We analyzed a library of mutants obtained through Agrobacterium tumefaciens transformation system, looking for alterations in growth and reproductive structure formation. Two mutant strains were found to have lost the ability to form pycnidia. The flanking T-DNA insertion regions were identified on P. citricarpa genome by using blast analysis and further gene prediction. The predicted genes containing the T-DNA insertions were identified as Spindle Poison Sensitivity Scp3, Ion Transport protein, and Cullin Binding proteins. The Ion Transport and Cullin Binding proteins are known to be correlated with sexual and asexual reproduction in fungi; however, the exact mechanism by which these proteins act on spore formation in P. citricarpa needs to be better characterized. The Scp3 proteins are suggested here for the first time as being associated with asexual reproduction in fungus. This protein is associated with microtubule formation, and as microtubules play an essential role as spindle machinery for chromosome segregation and cytokinesis, insertions in this gene can lead to abnormal formations, such as that observed here in P. citricarpa. We suggest these genes as new targets for fungicide development and CBS disease control, by iRNA. Copyright © 2016 Elsevier GmbH. All rights reserved.

FigA, a putative homolog of low-affinity calcium system member Fig1 in Saccharomyces cerevisiae, is involved in growth and asexual and sexual development in Aspergillus nidulans.

PubMed

Zhang, Shizhu; Zheng, Hailin; Long, Nanbiao; Carbó, Natalia; Chen, Peiying; Aguilar, Pablo S; Lu, Ling

2014-02-01

Calcium-mediated signaling pathways are widely employed in eukaryotes and are implicated in the regulation of diverse biological processes. In Saccharomyces cerevisiae, at least two different calcium uptake systems have been identified: the high-affinity calcium influx system (HACS) and the low-affinity calcium influx system (LACS). Compared to the HACS, the LACS in fungi is not well known. In this study, FigA, a homolog of the LACS member Fig1 from S. cerevisiae, was functionally characterized in the filamentous fungus Aspergillus nidulans. Loss of figA resulted in retardant hyphal growth and a sharp reduction of conidial production. Most importantly, FigA is essential for the homothallic mating (self-fertilization) process; further, FigA is required for heterothallic mating (outcrossing) in the absence of HACS midA. Interestingly, in a figA deletion mutant, adding extracellular Ca(2+) rescued the hyphal growth defects but could not restore asexual and sexual reproduction. Furthermore, quantitative PCR results revealed that figA deletion sharply decreased the expression of brlA and nsdD, which are known as key regulators during asexual and sexual development, respectively. In addition, green fluorescent protein (GFP) tagging at the C terminus of FigA (FigA::GFP) showed that FigA localized to the center of the septum in mature hyphal cells, to the location between vesicles and metulae, and between the junctions of metulae and phialides in conidiophores. Thus, our findings suggest that FigA, apart from being a member of a calcium uptake system in A. nidulans, may play multiple unexplored roles during hyphal growth and asexual and sexual development.

Lineage dynamics and mutation-selection balance in non-adapting asexual populations

NASA Astrophysics Data System (ADS)

Pénisson, Sophie; Sniegowski, Paul D.; Colato, Alexandre; Gerrish, Philip J.

2013-02-01

In classical population genetics, mutation-selection balance refers to the equilibrium frequency of a deleterious allele established and maintained under two opposing forces: recurrent mutation, which tends to increase the frequency of the allele; and selection, which tends to decrease its frequency. In a haploid population, if μ denotes the per capita rate of production of the deleterious allele by mutation and s denotes the selective disadvantage of carrying the allele, then the classical mutation-selection balance frequency of the allele is approximated by μ/s. This calculation assumes that lineages carrying the mutant allele in question—the ‘focal allele’—do not accumulate deleterious mutations linked to the focal allele. In principle, indirect selection against the focal allele caused by such additional mutations can decrease the frequency of the focal allele below the classical mutation-selection balance. This effect of indirect selection will be strongest in an asexual population, in which the entire genome is in linkage. Here, we use an approach based on a multitype branching process to investigate this effect, analyzing lineage dynamics under mutation, direct selection, and indirect selection in a non-adapting asexual population. We find that the equilibrium balance between recurrent mutation to the focal allele and the forces of direct and indirect selection against the focal allele is closely approximated by γμ/(s + U) (s = 0 if the focal allele is neutral), where γ ≈ eθθ-(ω+θ)(ω + θ)(Γ(ω + θ) - Γ(ω + θ,θ)), \\theta =U/\\tilde {s}, and \\omega =s/\\tilde {s}; U denotes the genomic deleterious mutation rate and \\tilde {s} denotes the geometric mean selective disadvantage of deleterious mutations elsewhere on the genome. This mutation-selection balance for asexual populations can remain surprisingly invariant over wide ranges of the mutation rate.

An empirical approach to the stopping power of solids and gases for ions from 3Li to 18Ar

NASA Astrophysics Data System (ADS)

Paul, Helmut; Schinner, Andreas

2001-08-01

A large collection of stopping power data for projectiles from 3Li to 18Ar is investigated as a possible basis for producing a table of stopping powers. We divide the experimental stopping powers for a particular projectile (nuclear charge Z1) by those for alpha particles in the same element, as given in ICRU Report 49. With proper normalization, we then obtain experimental stopping power ratios Srel that lie approximately on a single curve, provided we treat solid and gaseous targets separately, and provided we exclude H 2 and He targets. For every projectile, this curve is then fitted by a 3-parameter sigmoid function Srel= Srel( a, b, c). We find that the three parameters a, b and c depend smoothly on Z1 and can themselves be fitted by suitable functions af, bf and cf of Z1, separately for solid and gaseous targets. The low energy limit (coefficient a) for solids agrees approximately with the prediction by Lindhard and Scharff. We find that agas< asol in almost all cases. Introducing the coefficients af , bf and cf in Srel, we can calculate the stopping power for any ion (3⩽ Z1⩽18), and for any element (except H 2 and He) and any mixture or compound contained in the ICRU table.

Sexual recombination as a tool for engineering industrial Penicillium chrysogenum strains.

PubMed

Dahlmann, Tim A; Böhm, Julia; Becker, Kordula; Kück, Ulrich

2015-11-01

The recent discovery and functional characterization of opposite mating-type loci in the industrial penicillin producer Penicillium chrysogenum demonstrated their regulatory role in sexual as well as asexual development. Subsequent experiments further showed that a sexual life cycle can be induced in P. chrysogenum that was for long believed to reproduce exclusively by asexual propagation. Finally, crossing of wild type and production strains resulted in the generation of recombinant ascospore isolates. We predict from these recent findings that recombinant progeny for industrial applications can be obtained by sexual crossings and discuss experimental difficulties that occur when parental strains with karyotype heterogeneity are used for mating.

DNA transposon dynamics in populations of Daphnia pulex with and without sex.

PubMed

Schaack, Sarah; Pritham, Ellen J; Wolf, Abby; Lynch, Michael

2010-08-07

We investigate the role of recombination in transposable element (TE) proliferation in the cyclical parthenogen, Daphnia pulex. Recombination provides a mechanism by which the rate of both TE gain and loss can be accelerated, a duality that has long intrigued many biologists interested in the influence of sex on mutation accumulation. We compared TE loads among populations of D. pulex where sex occurs regularly (cyclical parthenogens or 'sexuals') with those in which the ability to reproduce sexually has been completely lost (obligate 'asexuals') for six different families of DNA transposons. Transposon display assays showed that sexuals have more TEs than asexuals, contrary to the expectations under Muller's ratchet but consistent with the idea that sex facilitates TE spread. Sexuals also exhibit higher insertion site polymorphism among lineages, as predicted because recombination accelerates rates of loss and gain. Asexuals, however, have proportionally more singletons (loci occupied in a single isolate), which differs from previous studies where selfing and outcrossing were used as a proxy for high and low recombination. Our multi-element survey reveals that the impact of sex on TE proliferation is consistent among different Class II TE families and we discuss the genomic consequences of different reproductive strategies over long time periods.

Polymorphism and methylation patterns in Agave tequilana Weber var. 'Azul' plants propagated asexually by three different methods.

PubMed

Díaz-Martínez, Miriam; Nava-Cedillo, Alejandro; Guzmán-López, José Alfredo; Escobar-Guzmán, Rocío; Simpson, June

2012-04-01

Genetic variation in three forms of asexually propagated Agave tequilana Weber var. 'Azul' plants namely offsets, bulbils and in vitro cultured individuals was studied by AFLP analysis. Low levels of variation were observed between mother plants and offsets and a higher level between mother plant and bulbils. Families obtained from commercial plantations showed lower levels of variation in comparison to families grown as ornamentals. No variation was observed between the original explant and four generations of in vitro cultured plants. Epigenetic variation was also studied by analyzing changes in methylation patterns between mother plants and offspring in each form of asexual reproduction. Offsets and bulbils showed an overall decrease in methylation whereas in vitro cultured plants showed patterns specific to each generation: Generations 1 and 4 showed overall demethylation whereas Generations 2 and 3 showed increased methylation. Analysis of ESTs associated with transposable elements revealed higher proportions of ESTs from Ty1-copia-like, Gypsy and CACTA transposable elements in cDNA libraries obtained from pluripotent tissue suggesting a possible correlation between methylation patterns, expression of transposable element associated genes and somaclonal variation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Uniparental Inheritance Promotes Adaptive Evolution in Cytoplasmic Genomes.

PubMed

Christie, Joshua R; Beekman, Madeleine

2017-03-01

Eukaryotes carry numerous asexual cytoplasmic genomes (mitochondria and plastids). Lacking recombination, asexual genomes should theoretically suffer from impaired adaptive evolution. Yet, empirical evidence indicates that cytoplasmic genomes experience higher levels of adaptive evolution than predicted by theory. In this study, we use a computational model to show that the unique biology of cytoplasmic genomes-specifically their organization into host cells and their uniparental (maternal) inheritance-enable them to undergo effective adaptive evolution. Uniparental inheritance of cytoplasmic genomes decreases competition between different beneficial substitutions (clonal interference), promoting the accumulation of beneficial substitutions. Uniparental inheritance also facilitates selection against deleterious cytoplasmic substitutions, slowing Muller's ratchet. In addition, uniparental inheritance generally reduces genetic hitchhiking of deleterious substitutions during selective sweeps. Overall, uniparental inheritance promotes adaptive evolution by increasing the level of beneficial substitutions relative to deleterious substitutions. When we assume that cytoplasmic genome inheritance is biparental, decreasing the number of genomes transmitted during gametogenesis (bottleneck) aids adaptive evolution. Nevertheless, adaptive evolution is always more efficient when inheritance is uniparental. Our findings explain empirical observations that cytoplasmic genomes-despite their asexual mode of reproduction-can readily undergo adaptive evolution. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Facultative parthenogenesis in the Ryukyu drywood termite Neotermes koshunensis

PubMed Central

Kobayashi, Kazuya; Miyaguni, Yasushi

2016-01-01

Parthenogenesis is a relatively rare reproductive mode in nature compared to sex. In social insects, the evolution of parthenogenesis has a notable impact on their life histories. Some termites with parthenogenetic ability produce numerous non-dispersing supplementary queens asexually, whereas other castes are produced via sexual reproduction. This asexual queen succession (AQS) system is adaptive because hundreds of the asexual queens improve the reproductive potential of the colony and maintain the genetic diversity within the colony. However, the evolutionary process of the AQS system remains unclear because parthenogenetic species without this system are unknown. Here, we report facultative parthenogenesis in the drywood termite Neotermes koshunensis. Although the eggs produced by females isolated from males hatched, the hatching rate of those eggs was lower than that of the eggs produced by females kept with males. These parthenogenetic offspring inherited only the maternal alleles and showed high homozygosity, which indicates that the mechanism of ploidy restoration is terminal fusion. A previous study showed that most colonies of this species have a single queen or orphan; thus, the AQS system has not evolved despite their parthenogenetic ability. Further investigations of N. koshunensis will reveal how parthenogenesis evolved and its role in the insect societies. PMID:27464523

Facultative parthenogenesis in the Ryukyu drywood termite Neotermes koshunensis.

PubMed

Kobayashi, Kazuya; Miyaguni, Yasushi

2016-07-28

Parthenogenesis is a relatively rare reproductive mode in nature compared to sex. In social insects, the evolution of parthenogenesis has a notable impact on their life histories. Some termites with parthenogenetic ability produce numerous non-dispersing supplementary queens asexually, whereas other castes are produced via sexual reproduction. This asexual queen succession (AQS) system is adaptive because hundreds of the asexual queens improve the reproductive potential of the colony and maintain the genetic diversity within the colony. However, the evolutionary process of the AQS system remains unclear because parthenogenetic species without this system are unknown. Here, we report facultative parthenogenesis in the drywood termite Neotermes koshunensis. Although the eggs produced by females isolated from males hatched, the hatching rate of those eggs was lower than that of the eggs produced by females kept with males. These parthenogenetic offspring inherited only the maternal alleles and showed high homozygosity, which indicates that the mechanism of ploidy restoration is terminal fusion. A previous study showed that most colonies of this species have a single queen or orphan; thus, the AQS system has not evolved despite their parthenogenetic ability. Further investigations of N. koshunensis will reveal how parthenogenesis evolved and its role in the insect societies.

Morphological alterations in the freshwater rotifer Brachionus calyciflorus Pallas 1766 (Rotifera: Monogononta) caused by vinclozolin chronic exposure.

PubMed

Alvarado-Flores, Jesús; Rico-Martínez, Roberto; Adabache-Ortíz, Araceli; Silva-Briano, Marcelo

2015-05-01

Vinclozolin (VZ) is a dicarboximide fungicide widely used on fruits, vegetables and wines, effective against fungi plagues. In this study we characterized the effects of VZ using a 4-day reproductive chronic assay with the freshwater rotifer Brachionus calyciflorus. The assay included observations of several features of asexual and sexual reproduction. Our results indicate that VZ: (a) increased asexual and sexual reproduction, (b) caused severe abnormality in females and (c) these abnormalities were inherited by sexual and asexual reproduction. At 1.2 mg/L three abnormal females were found out of 457 total females (0.66 %). This low percentage is consistent and reproducible according to further analysis, where we increased the number of replicates and total females exposed to 1.2 mg/L of VZ, and found 18 abnormal females out of 2868 total females (0.63 % abnormality). Interestingly, abnormal females found at 5.6 mg/L VZ exposure, were able to show mating behavior. Our results suggest that VZ behaves as a strong endocrine disruptor whose effects show the characteristic inverted-U-shape exposure concentration response curve regarding the intrinsic population increase and the percentage of abnormalities as endpoints.

Anaemia following Artemisinin-Based Combination Treatments of Uncomplicated Plasmodium falciparum Malaria in Children: Temporal Patterns of Haematocrit and the Use of Uncomplicated Hyperparasitaemia as a Model for Evaluating Late-Appearing Anaemia.

PubMed

Sowunmi, Akin; Akano, Kazeem; Ntadom, Godwin; Ayede, Adejumoke; Oguche, Stephen; Agomo, Chimere; Okafor, Henrietta; Watila, Ismaila; Meremikwu, Martin; Ogala, William; Agomo, Philip; Adowoye, Elsie; Fatunmbi, Bayo; Aderoyeje, Temitope; Happi, Christian; Gbotosho, Grace; Folarin, Onikepe

2017-01-01

In severe malaria, intravenous artesunate may cause delayed haemolytic anaemia but there has been little evaluation of the propensity of oral artemisinin-based combination treatments (ACTs) to cause late-appearing anaemia. The frequency of anaemia (haematocrit <30%), and temporal changes in haematocrit were evaluated in 1,191 malarious children following ACTs. "Haematocrit conservation" was evaluated by using the fall in haematocrit/1,000 asexual parasites cleared from the peripheral blood (FIH/1,000 asexual parasites cpb), and the ratio of the average haematocrit (on the first 3 days of starting treatment):total parasitaemia cleared. The frequency of anaemia decreased significantly following treatment. FIH/1,000 asexual parasites cpb, average haematocrit:total parasitaemia cleared, and mean haematocrit 5 weeks after treatment began were significantly lower in hyperparasitaemic children than in children without hyperparasitaemia, suggesting haematocrit conservation during treatment followed later by a loss of haematocrit. Asymptomatic late-appearing anaemia occurred in 6% of the children. Artesunate-amodiaquine and artemether-lumefantrine contribute to haematocrit conservation at high parasitaemias but may cause late-appearing anaemia. © 2017 S. Karger AG, Basel.

Artemisone and artemiside - potent pan-reactive antimalarial agents that also synergize redox imbalance in P. falciparum transmissible gametocyte stages.

PubMed

Coertzen, Dina; Reader, Janette; van der Watt, Mariëtte; Nondaba, Sindisiwe H; Gibhard, Liezl; Wiesner, Lubbe; Smith, Peter; D'Alessandro, Sarah; Taramelli, Donatella; Ning Wong, Ho; du Preez, Jan L; Wu, Ronald Wai Keung; Birkholtz, Lyn-Marie; Haynes, Richard K

2018-06-04

The emergence of resistance towards artemisinin combination therapies (ACTs) by the malaria parasite Plasmodium falciparum has the potential to severely compromise malaria control. Therefore, development of new artemisinins in combination with new drugs that impart activities towards both intraerythrocytic proliferative asexual and transmissible gametocyte stages, in particular those of resistant parasites, are urgently required. We define artemisinins as oxidant drugs through their ability to oxidize reduced flavin cofactors of flavin disulfide reductases critical for maintaining redox-homeostasis in the malaria parasite. Here we compare the activities of 10-amino artemisinin derivatives towards the asexual and gametocyte stages of P. falciparum parasites. Of these, artemisone and artemiside inhibited asexual and gametocyte stages, particularly stage V gametocytes in the low nM range. Further, treatment of both early and late gametocyte stages with artemisone or artemiside combined with the pro-oxidant redox partner methylene blue displays notable synergism. These data suggest that modulation of redox-homeostasis likely is an important druggable process, particularly in gametocytes, and thereby enhances the prospect of using combinations of oxidant and redox drugs for malaria control. Copyright © 2018 American Society for Microbiology.

CRISPR-Cas9-modified pfmdr1 protects Plasmodium falciparum asexual blood stages and gametocytes against a class of piperazine-containing compounds but potentiates artemisinin-based combination therapy partner drugs.

PubMed

Ng, Caroline L; Siciliano, Giulia; Lee, Marcus C S; de Almeida, Mariana J; Corey, Victoria C; Bopp, Selina E; Bertuccini, Lucia; Wittlin, Sergio; Kasdin, Rachel G; Le Bihan, Amélie; Clozel, Martine; Winzeler, Elizabeth A; Alano, Pietro; Fidock, David A

2016-08-01

Emerging resistance to first-line antimalarial combination therapies threatens malaria treatment and the global elimination campaign. Improved therapeutic strategies are required to protect existing drugs and enhance treatment efficacy. We report that the piperazine-containing compound ACT-451840 exhibits single-digit nanomolar inhibition of the Plasmodium falciparum asexual blood stages and transmissible gametocyte forms. Genome sequence analyses of in vitro-derived ACT-451840-resistant parasites revealed single nucleotide polymorphisms in pfmdr1, which encodes a digestive vacuole membrane-bound ATP-binding cassette transporter known to alter P. falciparum susceptibility to multiple first-line antimalarials. CRISPR-Cas9 based gene editing confirmed that PfMDR1 point mutations mediated ACT-451840 resistance. Resistant parasites demonstrated increased susceptibility to the clinical drugs lumefantrine, mefloquine, quinine and amodiaquine. Stage V gametocytes harboring Cas9-introduced pfmdr1 mutations also acquired ACT-451840 resistance. These findings reveal that PfMDR1 mutations can impart resistance to compounds active against asexual blood stages and mature gametocytes. Exploiting PfMDR1 resistance mechanisms provides new opportunities for developing disease-relieving and transmission-blocking antimalarials. © 2016 John Wiley & Sons Ltd.

Wnt affects symmetry and morphogenesis during post-embryonic development in colonial chordates.

PubMed

Di Maio, Alessandro; Setar, Leah; Tiozzo, Stefano; De Tomaso, Anthony W

2015-01-01

Wnt signaling is one of the earliest and most highly conserved regulatory pathways for the establishment of the body axes during regeneration and early development. In regeneration, body axes determination occurs independently of tissue rearrangement and early developmental cues. Modulation of the Wnt signaling in either process has shown to result in unusual body axis phenotypes. Botryllus schlosseri is a colonial ascidian that can regenerate its entire body through asexual budding. This processes leads to an adult body via a stereotypical developmental pathway (called blastogenesis), without proceeding through any embryonic developmental stages. In this study, we describe the role of the canonical Wnt pathway during the early stages of asexual development. We characterized expression of three Wnt ligands (Wnt2B, Wnt5A, and Wnt9A) by in situ hybridization and qRT-PCR. Chemical manipulation of the pathway resulted in atypical budding due to the duplication of the A/P axes, supernumerary budding, and loss of the overall cell apical-basal polarity. Our results suggest that Wnt signaling is used for equivalent developmental processes both during embryogenesis and asexual development in an adult organism, suggesting that patterning mechanisms driving morphogenesis are conserved, independent of embryonic, or regenerative development.

Memory and obesity affect the population dynamics of asexual freshwater planarians

NASA Astrophysics Data System (ADS)

Dunkel, Jörn; Talbot, Jared; Schötz, Eva-Maria

2011-04-01

Asexual reproduction in multicellular organisms is a complex biophysical process that is not yet well understood quantitatively. Here, we report a detailed population study for the asexual freshwater planarian Schmidtea mediterranea, which can reproduce via transverse fission due to a large stem cell contingent. Our long-term observations of isolated non-interacting planarian populations reveal that the characteristic fission waiting time distributions for head and tail fragments differ significantly from each other. The stochastic fission dynamics of tail fragments exhibits non-negligible memory effects, implying that an accurate mathematical description of future data should be based on non-Markovian tree models. By comparing the effective growth of non-interacting planarian populations with those of self-interacting populations, we are able to quantify the influence of interactions between flatworms and physical conditions on the population growth. A surprising result is the non-monotonic relationship between effective population growth rate and nutrient supply: planarians exhibit a tendency to become 'obese' if the feeding frequency exceeds a critical level, resulting in a decreased reproduction activity. This suggests that these flatworms, which possess many genes homologous to those of humans, could become a new model system for studying dietary effects on reproduction and regeneration in multicellular organisms.

How Large Asexual Populations Adapt

NASA Astrophysics Data System (ADS)

Desai, Michael

2007-03-01

We often think of beneficial mutations as being rare, and of adaptation as a sequence of selected substitutions: a beneficial mutation occurs, spreads through a population in a selective sweep, then later another beneficial mutation occurs, and so on. This simple picture is the basis for much of our intuition about adaptive evolution, and underlies a number of practical techniques for analyzing sequence data. Yet many large and mostly asexual populations -- including a wide variety of unicellular organisms and viruses -- live in a very different world. In these populations, beneficial mutations are common, and frequently interfere or cooperate with one another as they all attempt to sweep simultaneously. This radically changes the way these populations adapt: rather than an orderly sequence of selective sweeps, evolution is a constant swarm of competing and interfering mutations. I will describe some aspects of these dynamics, including why large asexual populations cannot evolve very quickly and the character of the diversity they maintain. I will explain how this changes our expectations of sequence data, how sex can help a population adapt, and the potential role of ``mutator'' phenotypes with abnormally high mutation rates. Finally, I will discuss comparisons of these predictions with evolution experiments in laboratory yeast populations.

The interplay between the effectiveness of the grass-endophyte mutualism and the genetic variability of the host plant

PubMed Central

Gundel, Pedro E; Omacini, Marina; Sadras, Victor O; Ghersa, Claudio M

2010-01-01

Neotyphodium endophytic fungi, the asexual state of Epichloë species, protect cool-season grasses against stresses. The outcomes of Neotyphodium-grass symbioses are agronomically relevant as they may affect the productivity of pastures. It has been suggested that the mutualism is characteristic of agronomic grasses and that differential rates of gene flow between both partners’ populations are expected to disrupt the specificity of the association and, thus, the mutualism in wild grasses. We propose that compatibility is necessary but not sufficient to explain the outcomes of Neotyphodium-grass symbiosis, and advance a model that links genetic compatibility, mutualism effectiveness, and endophyte transmission efficiency. For endophytes that reproduce clonally and depend on allogamous hosts for reproduction and dissemination, we propose that this symbiosis works as an integrated entity where gene flow promotes its fitness and evolution. Compatibility between the host plant and the fungal endophyte would be high in genetically close parents; however, mutualism effectiveness and transmission efficiency would be low in fitness depressed host plants. Increasing the genetic distance of mating parents would increase mutualism effectiveness and transmission efficiency. This tendency would be broken when the genetic distance between parents is high (out-breeding depression). Our model allows for testable hypotheses that would contribute to understand the coevolutionary origin and future of the endophyte-grass mutualism. PMID:25567945

Selection on overdominant genes maintains heterozygosity along multiple chromosomes in a clonal lineage of honey bee.

PubMed

Goudie, Frances; Allsopp, Michael H; Oldroyd, Benjamin P

2014-01-01

Correlations between fitness and genome-wide heterozygosity (heterozygosity-fitness correlations, HFCs) have been reported across a wide range of taxa. The genetic basis of these correlations is controversial: do they arise from genome-wide inbreeding ("general effects") or the "local effects" of overdominant loci acting in linkage disequilibrium with neutral loci? In an asexual thelytokous lineage of the Cape honey bee (Apis mellifera capensis), the effects of inbreeding have been homogenized across the population, making this an ideal system in which to detect overdominant loci, and to make inferences about the importance of overdominance on HFCs in general. Here we investigate the pattern of zygosity along two chromosomes in 42 workers from the clonal Cape honey bee population. On chromosome III (which contains the sex-locus, a gene that is homozygous-lethal) and chromosome IV we show that the pattern of zygosity is characterized by loss of heterozygosity in short regions followed by the telomeric restoration of heterozygosity. We infer that at least four selectively overdominant genes maintain heterozygosity on chromosome III and three on chromosome IV via local effects acting on neutral markers in linkage disequilibrium. We conclude that heterozygote advantage and local effects may be more common and evolutionarily significant than is generally appreciated. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Profound Effects of Population Density on Fitness-Related Traits in an Invasive Freshwater Snail

PubMed Central

Zachar, Nicholas; Neiman, Maurine

2013-01-01

Population density can profoundly influence fitness-related traits and population dynamics, and density dependence plays a key role in many prominent ecological and evolutionary hypotheses. Here, we evaluated how individual-level changes in population density affect growth rate and embryo production early in reproductive maturity in two different asexual lineages of Potamopyrgus antipodarum, a New Zealand freshwater snail that is an important model system for ecotoxicology and the evolution of sexual reproduction as well as a potentially destructive worldwide invader. We showed that population density had a major influence on individual growth rate and early-maturity embryo production, effects that were often apparent even when comparing treatments that differed in population density by only one individual. While individual growth rate generally decreased as population density increased, we detected a hump-shaped relationship between embryo production and density, with females from intermediate-density treatments producing the most embryos and females from low- and high-density treatments producing the fewest embryos. The two lineages responded similarly to the treatments, indicating that these effects of population density might apply more broadly across P. antipodarum. These results indicate that there are profound and complex relationships between population density, growth rate, and early-maturity embryo production in at least two lineages of this important model system, with potential implications for the study of invasive populations, research on the maintenance of sex, and approaches used in ecotoxicology. PMID:24278240

Profound effects of population density on fitness-related traits in an invasive freshwater snail.

PubMed

Zachar, Nicholas; Neiman, Maurine

2013-01-01

Population density can profoundly influence fitness-related traits and population dynamics, and density dependence plays a key role in many prominent ecological and evolutionary hypotheses. Here, we evaluated how individual-level changes in population density affect growth rate and embryo production early in reproductive maturity in two different asexual lineages of Potamopyrgus antipodarum, a New Zealand freshwater snail that is an important model system for ecotoxicology and the evolution of sexual reproduction as well as a potentially destructive worldwide invader. We showed that population density had a major influence on individual growth rate and early-maturity embryo production, effects that were often apparent even when comparing treatments that differed in population density by only one individual. While individual growth rate generally decreased as population density increased, we detected a hump-shaped relationship between embryo production and density, with females from intermediate-density treatments producing the most embryos and females from low- and high-density treatments producing the fewest embryos. The two lineages responded similarly to the treatments, indicating that these effects of population density might apply more broadly across P. antipodarum. These results indicate that there are profound and complex relationships between population density, growth rate, and early-maturity embryo production in at least two lineages of this important model system, with potential implications for the study of invasive populations, research on the maintenance of sex, and approaches used in ecotoxicology.

Treatments options for alopecia.

PubMed

Iorizzo, Matilde; Tosti, Antonella

2015-01-01

Hair disorders have a very high social and psychological impact. Treatment is often frustrating and time-consuming both for the patients and the clinicians and requires special skills and expertise. This paper aims to provide an overview of available treatments for the most common forms of alopecia in adults (androgenetic alopecia [AGA], alopecia areata and cicatricial alopecias) after reviewing the literature in PubMed, Google Scholar and ClinicalTrial.gov. Before starting treatment, it is very important to confirm diagnosis and discuss patient's expectations. Treatment of hair disorders requires time and first results are usually visible a few months after beginning of therapy. Treatment of most hair disorders is mostly not evidenced-based as randomized controlled trials are available only for AGA.

Cost-Effectiveness of Screening Individuals With Cystic Fibrosis for Colorectal Cancer.

PubMed

Gini, Andrea; Zauber, Ann G; Cenin, Dayna R; Omidvari, Amir-Houshang; Hempstead, Sarah E; Fink, Aliza K; Lowenfels, Albert B; Lansdorp-Vogelaar, Iris

2017-12-27

Individuals with cystic fibrosis are at increased risk of colorectal cancer (CRC) compared to the general population, and risk is higher among those who received an organ transplant. We performed a cost-effectiveness analysis to determine optimal CRC screening strategies for patients with cystic fibrosis. We adjusted the existing Microsimulation Screening Analysis-Colon microsimulation model to reflect increased CRC risk and lower life expectancy in patients with cystic fibrosis. Modeling was performed separately for individuals who never received an organ transplant and patients who had received an organ transplant. We modeled 76 colonoscopy screening strategies that varied the age range and screening interval. The optimal screening strategy was determined based on a willingness to pay threshold of $100,000 per life-year gained. Sensitivity and supplementary analyses were performed, including fecal immunochemical test (FIT) as an alternative test, earlier ages of transplantation, and increased rates of colonoscopy complications, to assess whether optimal screening strategies would change. Colonoscopy every 5 years, starting at age 40 years, was the optimal colonoscopy strategy for patients with cystic fibrosis who never received an organ transplant; this strategy prevented 79% of deaths from CRC. Among patients with cystic fibrosis who had received an organ transplant, optimal colonoscopy screening should start at an age of 30 or 35 years, depending on the patient's age at time of transplantation. Annual FIT screening was predicted to be cost-effective for patients with cystic fibrosis. However, the level of accuracy of the FIT in population is not clear. Using a Microsimulation Screening Analysis-Colon microsimulation model, we found screening of patients with cystic fibrosis for CRC to be cost-effective. Due to the higher risk in these patients for CRC, screening should start at an earlier age with a shorter screening interval. The findings of this study (especially those on FIT screening) may be limited by restricted evidence available for patients with cystic fibrosis. Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.

Cost Effectiveness of Screening Individuals With Cystic Fibrosis for Colorectal Cancer.

PubMed

Gini, Andrea; Zauber, Ann G; Cenin, Dayna R; Omidvari, Amir-Houshang; Hempstead, Sarah E; Fink, Aliza K; Lowenfels, Albert B; Lansdorp-Vogelaar, Iris

2018-02-01

Individuals with cystic fibrosis are at increased risk of colorectal cancer (CRC) compared with the general population, and risk is higher among those who received an organ transplant. We performed a cost-effectiveness analysis to determine optimal CRC screening strategies for patients with cystic fibrosis. We adjusted the existing Microsimulation Screening Analysis-Colon model to reflect increased CRC risk and lower life expectancy in patients with cystic fibrosis. Modeling was performed separately for individuals who never received an organ transplant and patients who had received an organ transplant. We modeled 76 colonoscopy screening strategies that varied the age range and screening interval. The optimal screening strategy was determined based on a willingness to pay threshold of $100,000 per life-year gained. Sensitivity and supplementary analyses were performed, including fecal immunochemical test (FIT) as an alternative test, earlier ages of transplantation, and increased rates of colonoscopy complications, to assess if optimal screening strategies would change. Colonoscopy every 5 years, starting at an age of 40 years, was the optimal colonoscopy strategy for patients with cystic fibrosis who never received an organ transplant; this strategy prevented 79% of deaths from CRC. Among patients with cystic fibrosis who had received an organ transplant, optimal colonoscopy screening should start at an age of 30 or 35 years, depending on the patient's age at time of transplantation. Annual FIT screening was predicted to be cost-effective for patients with cystic fibrosis. However, the level of accuracy of the FIT in this population is not clear. Using a Microsimulation Screening Analysis-Colon model, we found screening of patients with cystic fibrosis for CRC to be cost effective. Because of the higher risk of CRC in these patients, screening should start at an earlier age with a shorter screening interval. The findings of this study (especially those on FIT screening) may be limited by restricted evidence available for patients with cystic fibrosis. Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.

Efficacy and safety of 3% minoxidil versus combined 3% minoxidil / 0.1% finasteride in male pattern hair loss: a randomized, double-blind, comparative study.

PubMed

Tanglertsampan, Chuchai

2012-10-01

Topical minoxidil and oral finasteride have been used to treat men with androgenetic alopecia (AGA). There are concerns about side effects of oral finasteride especially erectile dysfunction. To compare the efficacy and safety of the 24 weeks application of 3% minoxidil lotion (MNX) versus combined 3% minoxidil and 0.1% finasteride lotion (MFX) in men with AGA. Forty men with AGA were randomized treated with MNX or MFX. Efficacy was evaluated by hair counts and global photographic assessment. Safety assessment was performed by history and physical examination. At week 24, hair counts were increased from baseline in both groups. However paired t-test revealed statistical difference only in MFX group (p = 0.044). Unpaired t-test revealed no statistical difference between two groups with respect to change of hair counts at 24 weeks from baseline (p = 0.503). MFX showed significantly higher efficacy than MNX by global photographic assessment (p = 0.003). There was no significant difference in side effects between both groups. Although change of hair counts was not statistically different between two groups, global photographic assessment showed significantly greater improvement in the MFX group than the MNX group. There was no sexual side effect. MFX may be a safe and effective treatment option.

Insulin resistance and its association with catch-up growth in Chinese children born small for gestational age.

PubMed

Liu, Chunhua; Wu, Baiyan; Lin, Niyang; Fang, Xiaoyi

2017-01-01

To assess insulin resistance and β-cell function from birth to age 4 years and to examine their associations with catch-up growth (CUG) in Chinese small-for-gestational-age (SGA) children. Weight and height were measured yearly from birth to age 4 years, and transformed into age- and gender-adjusted SD scores. Fasting serum insulin and glucose were measured, and fasting insulin resistance and β-cell function were estimated using the homeostasis model assessment (HOMA). The mean HOMA-IR of the SGA group was significantly lower than that of the appropriate-for-gestational-age (AGA) group at ages 2 and 3 years old, and the mean HOMA% of the SGA group was significantly lower than that of the AGA group at age 4 years old. At 4 years of age, HOMA for insulin resistance was positively correlated with the height gain and SD of height gain between 0 and 5 months, and HOMA% was positively correlated with the weight gain and SD of weight gain between 6 and 12 months in SGA children. SGA children with CUG show a greater propensity to develop insulin resistance than AGA children between ages 2 and 4 years old. HOMA parameters are related to CUG in the first year of life. © 2016 The Obesity Society.

Automated Visualization and Quantification of Spiral Artery Blood Flow Entering the First-Trimester Placenta, Using 3-D Power Doppler Ultrasound.

PubMed

Stevenson, Gordon N; Noble, J Alison; Welsh, Alec W; Impey, Lawrence; Collins, Sally L

2018-03-01

The goal of our research was to quantify the placental vascularity in 3-D at 11-13 + 6 wk of pregnancy at precise distances from the utero-placental interface (UPI) using 3-D power Doppler ultrasound. With this automated image analysis technique, differences in vascularity between normal and pathologic pregnancies may be observed. The algorithm was validated using a computer-generated image phantom and applied retrospectively in 143 patients. The following features from the PD data were recorded: The number of spiral artery jets into the inter-villous space, total geometric and PD area. These were automatically measured at discrete millimeter distances from the UPI. Differences in features were compared with pregnancy outcomes: Pre-eclamptic versus normal, all small-for-gestational age (SGA) to appropriate-for-gestational age (AGA) patients and AGA versus SGA in normotensives (Mann-Whitney). The Benjamini-Hochberg procedure was used (false discovery rate 10%) for multiple comparison testing. Features decreased with increasing distance from the UPI (Kruskal-Wallis test; p <0.001). At 2- 3 mm from the UPI, all features were smaller in pre-eclamptic compared with normal patients and for some in SGA compared with AGA patients (p <0.05). For AGA versus SGA in normotensive patients, no significant differences were found. Number of jets measured at 2-5 mm from the UPI did not vary because of the position of the placenta in the uterus (ANOVA; p > 0.05). This method provides a new in-vivo imaging tool for examining spiral artery development through pregnancy. Size and number of entrances of blood flow into the UPI could potentially be used to identify high-risk pregnancies and may provide a new imaging biomarker for placental insufficiency. Copyright © 2018 World Federation for Ultrasound in Medicine and Biology. Published by Elsevier Inc. All rights reserved.

Functional role of gap junctions in cytokine-induced leukocyte adhesion to endothelium in vivo

PubMed Central

Véliz, Loreto P.; González, Francisco G.; Duling, Brian R.; Sáez, Juan C.; Boric, Mauricio P.

2008-01-01

To assess the hypothesis that gap junctions (GJs) participate on leukocyte-endothelium interactions in the inflammatory response, we compared leukocyte adhesion and transmigration elicited by cytokine stimulation in the presence or absence of GJ blockers in the hamster cheek pouch and also in the cremaster muscle of wild-type (WT) and endothelium-specific connexin 43 (Cx43) null mice (Cx43e−/−). In the cheek pouch, topical tumor necrosis factor-α (TNF-α; 150 ng/ml, 15 min) caused a sustained increment in the number of leukocytes adhered to venular endothelium (LAV) and located at perivenular regions (LPV). Superfusion with the GJ blockers 18-α-glycyrrhetinic acid (AGA; 75 μM) or 18-β-glycyrrhetinic acid (50 μM) abolished the TNF-α-induced increase in LAV and LPV; carbenoxolone (75 μM) or oleamide (100 μM) reduced LAV by 50 and 75%, respectively, and LPV to a lesser extent. None of these GJ blockers modified venular diameter, blood flow, or leukocyte rolling. In contrast, glycyrrhizin (75 μM), a non-GJ blocker analog of AGA, was devoid of effect. Interestingly, when AGA was removed 90 min after TNF-α stimulation, LAV started to rise at a similar rate as in control. Conversely, application of AGA 90 min after TNF-α reduced the number of previously adhered cells. In WT mice, intrascrotal injection of TNF-α (0.5 μg/0.3 ml) increased LAV (fourfold) and LPV (threefold) compared with saline-injected controls. In contrast to the observations in WT animals, TNF-α stimulation did not increase LAV or LPV in Cx43e−/− mice. These results demonstrate an important role for GJ communication in leukocyte adhesion and transmigration during acute inflammation in vivo and further suggest that endothelial Cx43 is key in these processes. PMID:18599597

Real-Time Monitoring of Results During First Year of Dutch Colorectal Cancer Screening Program and Optimization by Altering Fecal Immunochemical Test Cut-Off Levels.

PubMed

Toes-Zoutendijk, Esther; van Leerdam, Monique E; Dekker, Evelien; van Hees, Frank; Penning, Corine; Nagtegaal, Iris; van der Meulen, Miriam P; van Vuuren, Anneke J; Kuipers, Ernst J; Bonfrer, Johannes M G; Biermann, Katharina; Thomeer, Maarten G J; van Veldhuizen, Harriët; Kroep, Sonja; van Ballegooijen, Marjolein; Meijer, Gerrit A; de Koning, Harry J; Spaander, Manon C W; Lansdorp-Vogelaar, Iris

2017-03-01

After careful pilot studies and planning, the national screening program for colorectal cancer (CRC), with biennial fecal immunochemical tests (FITs), was initiated in The Netherlands in 2014. A national information system for real-time monitoring was developed to allow for timely evaluation. Data were collected from the first year of this screening program to determine the importance of planning and monitoring for optimal screening program performance. The national information system of the CRC screening program kept track of the number of invitations sent in 2014, FIT kits returned, and colonoscopies performed. Age-adjusted rates of participation, the number of positive test results, and positive predictive values (PPVs) for advanced neoplasia were determined weekly, quarterly, and yearly. In 2014, there were 741,914 persons invited for FIT; of these, 529,056 (71.3%; 95% CI, 71.2%-71.4%) participated. A few months into the program, real-time monitoring showed that rates of participation and positive test results (10.6%; 95% CI, 10.5%-10.8%) were higher than predicted and the PPV was lower (42.1%; 95% CI, 41.3%-42.9%) than predicted based on pilot studies. To reduce the burden of unnecessary colonoscopies and alleviate colonoscopy capacity, the cut-off level for a positive FIT result was increased from 15 to 47 μg Hb/g feces halfway through 2014. This adjustment decreased the percentage of positive test results to 6.7% (95% CI, 6.6%-6.8%) and increased the PPV to 49.1% (95% CI, 48.3%-49.9%). In total, the first year of the Dutch screening program resulted in the detection of 2483 cancers and 12,030 advanced adenomas. Close monitoring of the implementation of the Dutch national CRC screening program allowed for instant adjustment of the FIT cut-off levels to optimize program performance. Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.

Morphogenetic circuitry regulating growth and development in the dimorphic pathogen Penicillium marneffei.

PubMed

Boyce, Kylie J; Andrianopoulos, Alex

2013-02-01

Penicillium marneffei is an emerging human-pathogenic fungus endemic to Southeast Asia. Like a number of other fungal pathogens, P. marneffei exhibits temperature-dependent dimorphic growth and grows in two distinct cellular morphologies, hyphae at 25°C and yeast cells at 37°C. Hyphae can differentiate to produce the infectious agents, asexual spores (conidia), which are inhaled into the host lung, where they are phagocytosed by pulmonary alveolar macrophages. Within macrophages, conidia germinate into unicellular yeast cells, which divide by fission. This minireview focuses on the current understanding of the genes required for the morphogenetic control of conidial germination, hyphal growth, asexual development, and yeast morphogenesis in P. marneffei.

Harnessing recombination to speed adaptive evolution in Escherichia coli.

PubMed

Winkler, James; Kao, Katy C

2012-09-01

Evolutionary engineering typically involves asexual propagation of a strain to improve a desired phenotype. However, asexual populations suffer from extensive clonal interference, a phenomenon where distinct lineages of beneficial clones compete and are often lost from the population given sufficient time. Improved adaptive mutants can likely be generated by genetic exchange between lineages, thereby reducing clonal interference. We present a system that allows continuous in situ recombination by using an Esherichia coli F-based conjugation system lacking surface exclusion. Evolution experiments revealed that Hfr-mediated recombination significantly speeds adaptation in certain circumstances. These results show that our system is stable, effective, and suitable for use in evolutionary engineering applications. Copyright © 2012 Elsevier Inc. All rights reserved.

Screening for G6PD Deficiency Among Neonates with Neonatal Jaundice Admitted to Tertiary Care Center: A Need in Disguise.

PubMed

Kumar, Kishwer; Sohaila, Arjumand; Tikmani, Shiyam Sunder; Khan, Iqtidar Ahmed; Zafar, Anila

2015-08-01

This study was conducted to determine the association of Glucose-6-Phosphate Dehydrogenase (G-6-PD) deficiency among neonates admitted with jaundice at the neonatal intensive care unit, well baby nursery and neonatal step down nursery of the Aga Khan University Hospital, Karachi, Pakistan, from January to June 2010. A total of 205 neonates following the selection criteria were included. All selected neonates have their venous blood drawn, saved in EDTA bottle and sent to laboratory of The Aga Khan University Hospital (AKUH). The laboratory results of whether G-6-PD deficiency was present or not was recorded in the proforma. G-6-PD was deficient in 19 neonates (9.3%). All neonates were male.

Cytospora species from Populus and Salix in China with C. davidiana sp. nov.

PubMed

Wang, Yan-Li; Lu, Quan; Decock, Cony; Li, Yong-Xia; Zhang, Xing-Yao

2015-05-01

Poplar and willow plantations have become widespread in China, in order to meet national economic and environmental needs. The emergence of several pathogens is enhanced by climatic change and associated human factors. Species of Cytospora are well-known pathogens on poplar and willow, and cause stem cankers and diebacks. In the present study, we conducted a survey of Cytospora species occurring on Populus spp. and Salix spp. in China. We used morphological examination and phylogenetic inferences, based on the DNA sequence data from the internal transcribed spacer regions (ITS1, 5.8S rDNA, and ITS2) and partial β-tubulin gene, to identify six Cytospora species occurring on poplar and willow. Five of these species belonged to known taxa, viz. Cytospora chrysosperma (asexual state of Valsa sordida), Cytospora translucens (asexual state of Leucostoma translucens), Cytospora fugax (asexual state of Valsa salicina), Cytospora atrocirrhata, and Cytospora kantschavelii. Our study yielded a new species, Cytospora davidiana sp. nov., on poplar. The new species is characterized by typical torsellioid conidiomata. An additional Cytospora sp. 1, which formed a distinct clade in the phylogenetic inferences, remains unnamed; the paucity of available materials prevented phenotypical characterization. Copyright © 2015 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

A Global Survey of ATPase Activity in Plasmodium falciparum Asexual Blood Stages and Gametocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortega, Corrie; Frando, Andrew; Webb-Robertson, Bobbie-Jo

Effective malaria control and elimination in hyperendemic areas of the world will require treatment of disease-causing Plasmodium falciparum (Pf) blood stage infection but also blocking parasite transmission from humans to mosquito to prevent disease spread. Numerous antimalarial drugs have become ineffective due to parasite drug resistance and many currently used therapies do not kill gametocytes, highly specialized sexual parasite stages with distinct physiology that are necessary for transmission from the human host to the mosquito vector. Further confounding next generation drug development against Pf is the lack of known biochemical activity for most parasite gene products as well as themore » unknown metabolic needs of non-replicating gametocyte. Here, we take a systematic activity-based proteomics approach to survey the large and druggable ATPase family that is associated with replicating blood stage asexual parasites and transmissible gametocytes. We experimentally confirm existing annotation and predict ATPase function for 38 uncharacterized proteins. ATPase activity broadly changes during the transition from asexual schizonts to gametocytes, indicating altered metabolism and regulatory roles of ATPases specific for each lifecycle stage. By mapping the activity of ATPases associated with gametocytogenesis, we assign biochemical activity to a large number of uncharacterized proteins and identify new candidate transmission blocking targets.« less

Genome Reduction Uncovers a Large Dispensable Genome and Adaptive Role for Copy Number Variation in Asexually Propagated Solanum tuberosum[OPEN

PubMed Central

Hardigan, Michael A.; Crisovan, Emily; Hamilton, John P.; Laimbeer, Parker; Leisner, Courtney P.; Manrique-Carpintero, Norma C.; Newton, Linsey; Pham, Gina M.; Vaillancourt, Brieanne; Zeng, Zixian; Jiang, Jiming

2016-01-01

Clonally reproducing plants have the potential to bear a significantly greater mutational load than sexually reproducing species. To investigate this possibility, we examined the breadth of genome-wide structural variation in a panel of monoploid/doubled monoploid clones generated from native populations of diploid potato (Solanum tuberosum), a highly heterozygous asexually propagated plant. As rare instances of purely homozygous clones, they provided an ideal set for determining the degree of structural variation tolerated by this species and deriving its minimal gene complement. Extensive copy number variation (CNV) was uncovered, impacting 219.8 Mb (30.2%) of the potato genome with nearly 30% of genes subject to at least partial duplication or deletion, revealing the highly heterogeneous nature of the potato genome. Dispensable genes (>7000) were associated with limited transcription and/or a recent evolutionary history, with lower deletion frequency observed in genes conserved across angiosperms. Association of CNV with plant adaptation was highlighted by enrichment in gene clusters encoding functions for environmental stress response, with gene duplication playing a part in species-specific expansions of stress-related gene families. This study revealed unique impacts of CNV in a species with asexual reproductive habits and how CNV may drive adaption through evolution of key stress pathways. PMID:26772996

Lineage Selection and the Maintenance of Sex.

PubMed

de Vienne, Damien M; Giraud, Tatiana; Gouyon, Pierre-Henri

2013-01-01

Sex predominates in eukaryotes, despite its short-term disadvantage when compared to asexuality. Myriad models have suggested that short-term advantages of sex may be sufficient to counterbalance its twofold costs. However, despite decades of experimental work seeking such evidence, no evolutionary mechanism has yet achieved broad recognition as explanation for the maintenance of sex. We explore here, through lineage-selection models, the conditions favouring the maintenance of sex. In the first model, we allowed the rate of transition to asexuality to evolve, to determine whether lineage selection favoured species with the strongest constraints preventing the loss of sex. In the second model, we simulated more explicitly the mechanisms underlying the higher extinction rates of asexual lineages than of their sexual counterparts. We linked extinction rates to the ecological and/or genetic features of lineages, thereby providing a formalisation of the only figure included in Darwin's "The origin of species". Our results reinforce the view that the long-term advantages of sex and lineage selection may provide the most satisfactory explanations for the maintenance of sex in eukaryotes, which is still poorly recognized, and provide figures and a simulation website for training and educational purposes. Short-term benefits may play a role, but it is also essential to take into account the selection of lineages for a thorough understanding of the maintenance of sex.

Plasmodium falciparum Calcium-Dependent Protein Kinase 2 Is Critical for Male Gametocyte Exflagellation but Not Essential for Asexual Proliferation

PubMed Central

Molina-Cruz, Alvaro; Brzostowski, Joseph; Mu, Jianbing

2017-01-01

ABSTRACT Drug development efforts have focused mostly on the asexual blood stages of the malaria parasite Plasmodium falciparum. Except for primaquine, which has its own limitations, there are no available drugs that target the transmission of the parasite to mosquitoes. Therefore, there is a need to validate new parasite proteins that can be targeted for blocking transmission. P. falciparum calcium-dependent protein kinases (PfCDPKs) play critical roles at various stages of the parasite life cycle and, importantly, are absent in the human host. These features mark them as attractive drug targets. In this study, using CRISPR/Cas9 we successfully knocked out PfCDPK2 from blood-stage parasites, which was previously thought to be an indispensable protein. The growth rate of the PfCDPK2 knockout (KO) parasites was similar to that of wild-type parasites, confirming that PfCDPK2 function is not essential for the asexual proliferation of the parasite in vitro. The mature male and female gametocytes of PfCDPK2 KO parasites become round after induction. However, they fail to infect female Anopheles stephensi mosquitoes due to a defect(s) in male gametocyte exflagellation and possibly in female gametes. PMID:29042501

Widespread occurrence of lysine methylation in Plasmodium falciparum proteins at asexual blood stages.

PubMed

Kaur, Inderjeet; Zeeshan, Mohammad; Saini, Ekta; Kaushik, Abhinav; Mohmmed, Asif; Gupta, Dinesh; Malhotra, Pawan

2016-10-20

Post-transcriptional and post-translational modifications play a major role in Plasmodium life cycle regulation. Lysine methylation of histone proteins is well documented in several organisms, however in recent years lysine methylation of proteins outside histone code is emerging out as an important post-translational modification (PTM). In the present study we have performed global analysis of lysine methylation of proteins in asexual blood stages of Plasmodium falciparum development. We immunoprecipitated stage specific Plasmodium lysates using anti-methyl lysine specific antibodies that immunostained the asexual blood stage parasites. Using liquid chromatography and tandem mass spectrometry analysis, 570 lysine methylated proteins at three different blood stages were identified. Analysis of the peptide sequences identified 605 methylated sites within 422 proteins. Functional classification of the methylated proteins revealed that the proteins are mainly involved in nucleotide metabolic processes, chromatin organization, transport, homeostatic processes and protein folding. The motif analysis of the methylated lysine peptides reveals novel motifs. Many of the identified lysine methylated proteins are also interacting partners/substrates of PfSET domain proteins as revealed by STRING database analysis. Our findings suggest that the protein methylation at lysine residues is widespread in Plasmodium and plays an important regulatory role in diverse set of the parasite pathways.

Progressing the global antimalarial portfolio: finding drugs which target multiple Plasmodium life stages.

PubMed

Smith, Paul W; Diagana, Thierry T; Yeung, Bryan K S

2014-01-01

The number of novel antimalarial candidates entering preclinical development has seen an increase over the last several years. Most of these drug candidates were originally identified as hits coming from screening large chemical libraries specifically targeting the asexual blood stages of Plasmodium falciparum. Indeed, a large proportion of the current antimalarial arsenal has mainly targeted the asexual blood stage which is responsible for clinical symptoms of the disease. However, as part of the eradication agenda and to address resistance, any next-generation antimalarial should have additional activity on at least one other parasite life stage, i.e. gametocytocidal and/or tissue schizonticidal activity. We have applied this approach by screening compounds with intrinsic activity on asexual blood stages in assays against sexual and liver stages and identified two new antimalarial chemotypes with activity on multiple parasite life stages. This strategy can be expanded to identify other chemical classes of molecules with similar activity profiles for the next generation antimalarials. The following review summarizes the discovery of the spiroindolones and imidazolopiperazine classes of antimalarials developed by the NGBS consortium (Novartis Institute for Tropical Diseases, Genomic Institute of the Novartis Research Foundation, Biomedical Primate Research Center, and the Swiss Tropical and Public Health Institute) currently in clinical trials.

Within-population covariation between sexual reproduction and susceptibility to local parasites.

PubMed

Gibson, Amanda K; Xu, Julie Y; Lively, Curtis M

2016-09-01

Evolutionary biology has yet to reconcile the ubiquity of sex with its costs relative to asexual reproduction. Here, we test the hypothesis that coevolving parasites maintain sex in their hosts. Specifically, we examined the distributions of sexual reproduction and susceptibility to local parasites within a single population of freshwater snails (Potamopyrgus antipodarum). Susceptibility to local trematode parasites (Microphallus sp.) is a relative measure of the strength of coevolutionary selection in this system. Thus, if coevolving parasites maintain sex, sexual snails should be common where susceptibility is high. We tested this prediction in a mixed population of sexual and asexual snails by measuring the susceptibility of snails from multiple sites in a lake. Consistent with the prediction, the frequency of sexual snails was tightly and positively correlated with susceptibility to local parasites. Strikingly, in just two years, asexual females increased in frequency at sites where susceptibility declined. We also found that the frequency of sexual females covaries more strongly with susceptibility than with the prevalence of Microphallus infection in the field. In linking susceptibility to the frequency of sexual hosts, our results directly implicate spatial variation in coevolutionary selection in driving the geographic mosaic of sex. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

GmcA Is a Putative Glucose-Methanol-Choline Oxidoreductase Required for the Induction of Asexual Development in Aspergillus nidulans

PubMed Central

Etxebeste, Oier; Herrero-García, Erika; Cortese, Marc S.; Garzia, Aitor; Oiartzabal-Arano, Elixabet; de los Ríos, Vivian; Ugalde, Unai; Espeso, Eduardo A.

2012-01-01

Aspergillus nidulans asexual differentiation is induced by Upstream Developmental Activators (UDAs) that include the bZIP-type Transcription Factor (TF) FlbB. A 2D-PAGE/MS-MS-coupled screen for proteins differentially expressed in the presence and absence of FlbB identified 18 candidates. Most candidates belong to GO term classes involved in osmotic and/or oxidative stress response. Among these, we focused on GmcA, a putative glucose-methanol-choline oxidoreductase which is upregulated in a ΔflbB background. GmcA is not required for growth since no differences were detected in the radial extension upon deletion of gmcA. However, its activity is required to induce conidiation under specific culture conditions. A ΔgmcA strain conidiates profusely under acid conditions but displays a characteristic fluffy aconidial phenotype in alkaline medium. The absence of asexual development in a ΔgmcA strain can be suppressed, on one hand, using high concentrations of non-fermentable carbon sources like glycerol, and on the other hand, when the cMyb-type UDA TF flbD is overexpressed. Overall, the results obtained in this work support a role for GmcA at early stages of conidiophore initiation. PMID:22792266

Antiplasmodial activities of dyes against Plasmodium falciparum asexual and sexual stages: Contrasted uptakes of triarylmethanes Brilliant green, Green S (E142), and Patent Blue V (E131) by erythrocytes.

PubMed

Leba, Louis-Jérôme; Popovici, Jean; Estevez, Yannick; Pelleau, Stéphane; Legrand, Eric; Musset, Lise; Duplais, Christophe

2017-12-01

The search for safe antimalarial compounds acting against asexual symptom-responsible stages and sexual transmission-responsible forms of Plasmodium species is one of the major challenges in malaria elimination programs. So far, among current drugs approved for human use, only primaquine has transmission-blocking activity. The discovery of small molecules targeting different Plasmodium falciparum life stages remains a priority in antimalarial drug research. In this context, several independent studies have recently reported antiplasmodial and transmission-blocking activities of commonly used stains, dyes and fluorescent probes against P. falciparum including chloroquine-resistant isolates. Herein we have studied the antimalarial activities of dyes with different scaffold and we report that the triarylmethane dye (TRAM) Brilliant green inhibits the growth of asexual stages (IC 50  ≤ 2 μM) and has exflagellation-blocking activity (IC 50  ≤ 800 nM) against P. falciparum reference strains (3D7, 7G8) and chloroquine-resistant clinical isolate (Q206). In a second step we have investigated the antiplasmodial activities of two polysulfonated triarylmethane food dyes. Green S (E142) is weakly active against P. falciparum asexual stage (IC 50 ≃ 17 μM) whereas Patent Blue V (E131) is inactive in both antimalarial assays. By applying liquid chromatography techniques for the culture supernatant analysis after cell washings and lysis, we report the detection of Brilliant green in erythrocytes, the selective uptake of Green S (E142) by infected erythrocytes, whereas Patent Blue V (E131) could not be detected within non-infected and 3D7-infected erythrocytes. Overall, our results suggest that two polysulfonated food dyes might display different affinity with transporters or channels on infected RBC membrane. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Gα proteins Gvm2 and Gvm3 regulate vegetative growth, asexual development, and pathogenicityon apple in Valsa mali.

PubMed

Song, Na; Dai, Qingqing; Zhu, Baitao; Wu, Yuxing; Xu, Ming; Voegele, Ralf Thomas; Gao, Xiaoning; Kang, Zhensheng; Huang, Lili

2017-01-01

In fungi, heterotrimeric guanine-nucleotide binding proteins (G-proteins) are key elements of signal transduction pathways, which control growth, asexual and sexual development, as well as virulence. In this study, we have identified two genes encoding heterotrimeric G protein alpha subunits, named Gvm2 and Gvm3, from Valsa mali, the causal agent of apple Valsa canker. Characterization of Gvm2 and Gvm3 mutants indicates that Gvm3 may be a crucial regulator of vegetative growth. Deletion of the corresponding gene results in a 20% reduction in growth rate. Besides, Gvm2 and Gvm3 seem to be involved in asexual reproduction, and mutants are hypersensitive to oxidative and cell membrane stresses. Interestingly, both G protein alpha subunits were most probably involved in V. mali virulence. In infection assays using Malus domestica cv. 'Fuji' leaves and twigs, the size of lesions caused by deletion mutants △Gvm2, or △Gvm3 are significantly reduced. Furthermore, many genes encoding hydrolytic enzymes-important virulence factors in V. mali-are expressed at a lower level in these deletion mutants. Our results suggest that Gvm2 and Gvm3 play an important role in virulence probably by regulation of expression of cell wall degrading enzymes. △Gvm2, and △Gvm3 mutants were further analyzed with respect to their impact on the transcript levels of genes in the cAMP/PKA pathway. The expression of the genes encoding adenylate cyclase VmAC, protein kinase A (PKA) regulatory subunit VmPKR, and PKA catalytic subunit VmPKA1 are down-regulated in both mutants. Further analyses indicated that intracellular cAMP level and PKA activity are down-regulated in the △Gvm3 mutant, but are basically unchanged in the △Gvm2 mutant. Overall, our findings indicate that both Gvm2 and Gvm3 play diverse roles in the modulation of vegetative growth, asexual development, and virulence in V. mali.

Intelligent Space Tube Optimization for speeding ground water remedial design.

PubMed

Kalwij, Ineke M; Peralta, Richard C

2008-01-01

An innovative Intelligent Space Tube Optimization (ISTO) two-stage approach facilitates solving complex nonlinear flow and contaminant transport management problems. It reduces computational effort of designing optimal ground water remediation systems and strategies for an assumed set of wells. ISTO's stage 1 defines an adaptive mobile space tube that lengthens toward the optimal solution. The space tube has overlapping multidimensional subspaces. Stage 1 generates several strategies within the space tube, trains neural surrogate simulators (NSS) using the limited space tube data, and optimizes using an advanced genetic algorithm (AGA) with NSS. Stage 1 speeds evaluating assumed well locations and combinations. For a large complex plume of solvents and explosives, ISTO stage 1 reaches within 10% of the optimal solution 25% faster than an efficient AGA coupled with comprehensive tabu search (AGCT) does by itself. ISTO input parameters include space tube radius and number of strategies used to train NSS per cycle. Larger radii can speed convergence to optimality for optimizations that achieve it but might increase the number of optimizations reaching it. ISTO stage 2 automatically refines the NSS-AGA stage 1 optimal strategy using heuristic optimization (we used AGCT), without using NSS surrogates. Stage 2 explores the entire solution space. ISTO is applicable for many heuristic optimization settings in which the numerical simulator is computationally intensive, and one would like to reduce that burden.

Minigene-like inhibition of protein synthesis mediated by hungry codons near the start codon

PubMed Central

Jacinto-Loeza, Eva; Vivanco-Domínguez, Serafín; Guarneros, Gabriel; Hernández-Sánchez, Javier

2008-01-01

Rare AGA or AGG codons close to the initiation codon inhibit protein synthesis by a tRNA-sequestering mechanism as toxic minigenes do. To further understand this mechanism, a parallel analysis of protein synthesis and peptidyl-tRNA accumulation was performed using both a set of lacZ constructs where AGAAGA codons were moved codon by codon from +2, +3 up to +7, +8 positions and a series of 3–8 codon minigenes containing AGAAGA codons before the stop codon. β-Galactosidase synthesis from the AGAAGA lacZ constructs (in a Pth defective in vitro system without exogenous tRNA) diminished as the AGAAGA codons were closer to AUG codon. Likewise, β-galactosidase expression from the reporter +7 AGA lacZ gene (plus tRNA, 0.25 μg/μl) waned as the AGAAGAUAA minigene shortened. Pth counteracted both the length-dependent minigene effect on the expression of β-galactosidase from the +7 AGA lacZ reporter gene and the positional effect from the AGAAGA lacZ constructs. The +2, +3 AGAAGA lacZ construct and the shortest +2, +3 AGAAGAUAA minigene accumulated the highest percentage of peptidyl-tRNAArg4. These observations lead us to propose that hungry codons at early positions, albeit with less strength, inhibit protein synthesis by a minigene-like mechanism involving accumulation of peptidyl-tRNA. PMID:18583364

Factors related to respiration influencing survival and respiratory function in patients with amyotrophic lateral sclerosis: a retrospective study.

PubMed

Leonardis, L; Dolenc Grošelj, L; Vidmar, G

2012-12-01

Various breathing abnormalities (Neurology 2009; 73: 1218) have been proposed as indicators for the introduction of non-invasive positive-pressure ventilation (NIV) in patients with amyotrophic lateral sclerosis (ALS). We were interested in the usefulness of symptoms of respiratory insufficiency and abnormal results of daytime arterial gas analyses (AGA) as predictors of survival and the effect of NIV on respiratory volumes and pressures. Reported symptoms, respiratory subscore of the ALS Functional Rating Scale (ALSFRS-r), Norris scale (Norris-r), and AGA were retrospectively analyzed in 189 ALS patients. Longitudinal follow-up of forced vital capacity (FVC), maximal inspiratory and expiratory pressure (MIP, MEP), and sniff nasal pressure (SNP) were analyzed with regard to the introduction of NIV. Respiratory symptoms were a bad prognostic sign (P = 0.007). Abnormalities in Norris-r, ALSFRS-r, pO(2), pCO(2), and oxygen saturation tended to be associated with a shorter survival, although they were not statistically significant. NIV prolonged survival and reduced the decline in FVC (P = 0.007), MIP, MEP, and SNP (the last three were not statistically significant). Symptoms, abnormal FVC, and AGA do not always coincide, and they can appear in a different sequence. Any respiratory abnormality should prompt the clinician to start discussing NIV with the patient. NIV prolongs survival and improves respiratory function. © 2012 The Author(s) European Journal of Neurology © 2012 EFNS.

Pre-eclampsia- an additional risk factor for cognitive impairment at school age after intrauterine growth restriction and very preterm birth.

PubMed

Morsing, E; Maršál, K

2014-02-01

To explore the possible influence of pre-eclampsia on cognitive outcome in children born very preterm after intrauterine growth restriction (IUGR) and abnormal umbilical artery blood flow. Cognitive function was evaluated at 5-8 years of age with Wechsler scales in 34 children born before 30 gestational weeks after IUGR (PT-IUGR) (11 children were exposed to maternal pre-eclampsia, 23 non-exposed) and in 34 children with no maternal pre-eclampsia and birth weight appropriate-for-gestational age (PT-AGA) matched for gestational age at birth, gender and age at examination. The subjects in the PT-IUGR group exposed to maternal pre-eclampsia had lower mean verbal IQ (VIQ) (mean ± SD 74 ± 16) and lower full scale IQ (FSIQ) (70 ± 19) in comparison with both the non-exposed PT-IUGR (VIQ 89 ± 15; p=0.013; FSIQ 83 ± 14, p=0.029), and, the PT-AGA group (VIQ 96 ± 15, p<0.001; FSIQ 90 ± 14, p=0.001). The differences remained significant after adjustment for known confounders. VIQ and FSIQ did not differ between the non-exposed IUGR and PT-AGA children. Fetal exposure to maternal pre-eclampsia seems to have an additional negative impact to that of IUGR on cognitive function in children born very preterm. Copyright © 2013 Elsevier Ltd. All rights reserved.

Inhibition of inflammatory gene expression in keratinocytes using a composition containing carnitine, thioctic Acid and saw palmetto extract.

PubMed

Chittur, Sridar; Parr, Brian; Marcovici, Geno

2011-01-01

Chronic inflammation of the hair follicle (HF) is considered a contributing factor in the pathogenesis of androgenetic alopecia (AGA). Previously, we clinically tested liposterolic extract of Serenoa repens (LSESr) and its glycoside, β-sitosterol, in subjects with AGA and showed a highly positive response to treatment. In this study, we sought to determine whether blockade of inflammation using a composition containing LSESr as well as two anti-inflammatory agents (carnitine and thioctic acid) could alter the expression of molecular markers of inflammation in a well-established in vitro system. Using a well-validated assay representative of HF keratinocytes, specifically, stimulation of cultured human keratinocyte cells in vitro, we measured changes in gene expression of a spectrum of well-known inflammatory markers. Lipopolysaccharide (LPS) provided an inflammatory stimulus. In particular, we found that the composition effectively suppressed LPS-activated gene expression of chemokines, including CCL17, CXCL6 and LTB(4) associated with pathways involved in inflammation and apoptosis. Our data support the hypothesis that the test compound exhibits anti-inflammatory characteristics in a well-established in vitro assay representing HF keratinocyte gene expression. These findings suggest that 5-alpha reductase inhibitors combined with blockade of inflammatory processes could represent a novel two-pronged approach in the treatment of AGA with improved efficacy over current modalities.

Homocysteine in small-for-gestational age and appropriate-for-gestational age preterm neonates from mothers receiving folic acid supplementation.

PubMed

Gomes, Thushari S; Lindner, Ulrike; Tennekoon, Kamani H; Karandagoda, Wimal; Gortner, Ludwig; Obeid, Rima

2010-08-01

Prematurity and small-for-gestational age (SGA) neonates are at risk for postnatal complications. Concentrations of total homocysteine (tHcy) might be related to neonatal outcome. We hypothesized that concentrations of tHcy are not related to growth restriction in neonates from mothers receiving 5 mg/day folic acid. We studied a total of 133 preterm neonates from normotensive mothers; SGA (n=96) and appropriate-for-gestational age (AGA, n=37). Concentrations of tHcy, folate and vitamin B12 were measured in venous umbilical cord plasma. AGA preterm neonates had higher mean birth weight (BW) compared to SGA preterms (2472 g vs. 2007 g; p<0.001) of comparable mean gestational age (GA) (35.1 vs. 35.7 weeks; p=0.059). Concentrations of tHcy (4.86 vs. 4.95 micromol/L), folate (63.3 vs. 55.7 nmol/L), and vitamin B12 (409 vs. 394 pmol/L) were not significantly different between the groups. GA was a strong positive predictor, BW was a significant negative predictor of cord plasma folate. Vitamin B12 concentration was a significant negative predictor of cord tHcy. Concentrations of tHcy did not differ between SGA and AGA preterm neonates born to mothers supplemented with folic acid. This finding argues against a causal role for folate deficiency or increased tHcy in growth restriction.

Synthesis of nitrogen-doped activated graphene aerogel/gold nanoparticles and its application for electrochemical detection of hydroquinone and o-dihydroxybenzene

NASA Astrophysics Data System (ADS)

Juanjuan, Zhang; Ruiyi, Li; Zaijun, Li; Junkang, Liu; Zhiguo, Gu; Guangli, Wang

2014-04-01

Graphene aerogel materials have attracted increasing attention owing to their large specific surface area, high conductivity and electronic interactions. Here, we report for the first time a novel strategy for the synthesis of nitrogen-doped activated graphene aerogel/gold nanoparticles (N-doped AGA/GNs). First, the mixture of graphite oxide, 2,4,6-trihydroxybenzaldehyde, urea and potassium hydroxide was dispersed in water and subsequently heated to form a graphene oxide hydrogel. Then, the hydrogel was dried by freeze-drying and reduced by thermal annealing in an Ar/H2 environment in sequence. Finally, GNs were adsorbed on the surface of the N-doped AGA. The resulting N-doped AGA/GNs offers excellent electronic conductivity (2.8 × 103 S m-1), specific surface area (1258 m2 g-1), well-defined 3D hierarchical porous structure and apparent heterogeneous electron transfer rate constant (40.78 +/- 0.15 cm s-1), which are notably better than that of previous graphene aerogel materials. Moreover, the N-doped AGA/GNs was used as a new sensing material for the electrochemical detection of hydroquinone (HQ) and o-dihydroxybenzene (DHB). Owing to the greatly enhanced electron transfer and mass transport, the sensor displays ultrasensitive electrochemical response to HQ and DHB. Its differential pulse voltammetric peak current linearly increases with the increase of HQ and DHB in the range of 5.0 × 10-8 to 1.8 × 10-4 M for HQ and 1 × 10-8 to 2.0 × 10-4 M for DHB. The detection limit is 1.5 × 10-8 M for HQ and 3.3 × 10-9 M for DHB (S/N = 3). This method provides the advantage of sensitivity, repeatability and stability compared with other HQ and DHB sensors. The sensor has been successfully applied to detection of HQ and DHB in real water samples with the spiked recovery in the range of 96.8-103.2%. The study also provides a promising approach for the fabrication of various graphene aerogel materials with improved electrochemical performances, which can be potentially applied in biosensors, electrocatalysis, and energy storage/conversion devices.Graphene aerogel materials have attracted increasing attention owing to their large specific surface area, high conductivity and electronic interactions. Here, we report for the first time a novel strategy for the synthesis of nitrogen-doped activated graphene aerogel/gold nanoparticles (N-doped AGA/GNs). First, the mixture of graphite oxide, 2,4,6-trihydroxybenzaldehyde, urea and potassium hydroxide was dispersed in water and subsequently heated to form a graphene oxide hydrogel. Then, the hydrogel was dried by freeze-drying and reduced by thermal annealing in an Ar/H2 environment in sequence. Finally, GNs were adsorbed on the surface of the N-doped AGA. The resulting N-doped AGA/GNs offers excellent electronic conductivity (2.8 × 103 S m-1), specific surface area (1258 m2 g-1), well-defined 3D hierarchical porous structure and apparent heterogeneous electron transfer rate constant (40.78 +/- 0.15 cm s-1), which are notably better than that of previous graphene aerogel materials. Moreover, the N-doped AGA/GNs was used as a new sensing material for the electrochemical detection of hydroquinone (HQ) and o-dihydroxybenzene (DHB). Owing to the greatly enhanced electron transfer and mass transport, the sensor displays ultrasensitive electrochemical response to HQ and DHB. Its differential pulse voltammetric peak current linearly increases with the increase of HQ and DHB in the range of 5.0 × 10-8 to 1.8 × 10-4 M for HQ and 1 × 10-8 to 2.0 × 10-4 M for DHB. The detection limit is 1.5 × 10-8 M for HQ and 3.3 × 10-9 M for DHB (S/N = 3). This method provides the advantage of sensitivity, repeatability and stability compared with other HQ and DHB sensors. The sensor has been successfully applied to detection of HQ and DHB in real water samples with the spiked recovery in the range of 96.8-103.2%. The study also provides a promising approach for the fabrication of various graphene aerogel materials with improved electrochemical performances, which can be potentially applied in biosensors, electrocatalysis, and energy storage/conversion devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00005f

Fixation probability of a nonmutator in a large population of asexual mutators.

PubMed

Jain, Kavita; James, Ananthu

2017-11-21

In an adapted population of mutators in which most mutations are deleterious, a nonmutator that lowers the mutation rate is under indirect selection and can sweep to fixation. Using a multitype branching process, we calculate the fixation probability of a rare nonmutator in a large population of asexual mutators. We show that when beneficial mutations are absent, the fixation probability is a nonmonotonic function of the mutation rate of the mutator: it first increases sublinearly and then decreases exponentially. We also find that beneficial mutations can enhance the fixation probability of a nonmutator. Our analysis is relevant to an understanding of recent experiments in which a reduction in the mutation rates has been observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Mathematical Model for Alternation of Polygamy and Parthenogenesis: Stability Versus Efficiency and Analogy with Parasitism.

PubMed

Sanchez-Palencia, Evariste; Lherminier, Philippe; Françoise, Jean-Pierre

2016-12-01

The present work is a contribution to the understanding of the sempiternal problem of the "burden of factor two" implied by sexual reproduction versus asexual one, as males are energy consumers not contributing to the production of offspring. We construct a deterministic mathematical model in population dynamics where a species enjoys both sexual and parthenogenetic capabilities of reproduction and lives on a limited resource. We then show how polygamy implies instability of a parthenogenetic population with a small number of sexually born males. This instability implies evolution of the system towards an attractor involving both (sexual and asexual) populations (which does not imply optimality of the population). We also exhibit the analogy with a parasite/host system.

Selection for sex in finite populations.

PubMed

Roze, D

2014-07-01

Finite population size generates interference between selected loci, which has been shown to favour increased rates of recombination. In this article, I present different analytical models exploring selection acting on a 'sex modifier locus' (that affects the relative investment into asexual and sexual reproduction) in a finite population. Two forms of selective forces act on the modifier: direct selection due to intrinsic costs associated with sexual reproduction and indirect selection generated by one or two other loci affecting fitness. The results show that indirect selective forces differ from those acting on a recombination modifier even in the case of a haploid population: in particular, a single selected locus generates indirect selection for sex, while two loci are required in the case of a recombination modifier. This effect stems from the fact that modifier alleles increasing sex escape more easily from low-fitness genetic backgrounds than alleles coding for lower rates of sex. Extrapolating the results from three-locus models to a large number of loci at mutation-selection balance indicates that in the parameter range where indirect selection is strong enough to outweigh a substantial cost of sex, interactions between selected loci have a stronger effect than the sum of individual effects of each selected locus. Comparisons with multilocus simulation results show that such extrapolations may provide correct predictions for the evolutionarily stable rate of sex, unless the cost of sex is high. © 2014 The Author. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Hitchhiking and epistasis give rise to cohort dynamics in adapting populations

PubMed Central

Buskirk, Sean W.; Peace, Ryan Emily; Lang, Gregory I.

2017-01-01

Beneficial mutations are the driving force of adaptive evolution. In asexual populations, the identification of beneficial alleles is confounded by the presence of genetically linked hitchhiker mutations. Parallel evolution experiments enable the recognition of common targets of selection; yet these targets are inherently enriched for genes of large target size and mutations of large effect. A comprehensive study of individual mutations is necessary to create a realistic picture of the evolutionarily significant spectrum of beneficial mutations. Here we use a bulk-segregant approach to identify the beneficial mutations across 11 lineages of experimentally evolved yeast populations. We report that nearly 80% of detected mutations have no discernible effects on fitness and less than 1% are deleterious. We determine the distribution of driver and hitchhiker mutations in 31 mutational cohorts, groups of mutations that arise synchronously from low frequency and track tightly with one another. Surprisingly, we find that one-third of cohorts lack identifiable driver mutations. In addition, we identify intracohort synergistic epistasis between alleles of hsl7 and kel1, which arose together in a low-frequency lineage. PMID:28720700

40 CFR 98.444 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

...), the American Gas Association (AGA), the American Society of Mechanical Engineers (ASME), the American... any flow meter calibrations performed are National Institute of Standards and Technology (NIST...

Identification of the Ga interstitial in Al(x)Ga(1-x)As by optically detected magnetic resonance

NASA Technical Reports Server (NTRS)

Kennedy, T. A.; Spencer, M. G.

1986-01-01

A new optically detected magnetic resonance spectrum in Al(x)Ga(1-x)As is reported and assigned to native Ga interstitials. Luminescence-quenching signals were observed over the energy region from 0.75 to 1.1 eV. The optically detected magnetic resonance is nearly isotropic, with spin-Hamiltonian parameters g = 2.025 + or - 0.006, central hyperfine splitting A(Ga-69) = 0.050 + or - 0.001/cm, and A(Ga-71) = 0.064 + or - 0.001/cm for H near the 001 line. The strong hyperfine coupling denotes an electronic state of A1 symmetry, which current theories predict for the Ga interstitial but not the Ga antisite. The slight anisotropy probably indicates that the Ga(i) is paired with a second, unknown defect.

Pathogenetic Influences of Human Herpesvirus 8 (HHV-8) in Prostate Cancer Progression

DTIC Science & Technology

2012-05-25

expression of each GOI were calculated by raising 2 to the negative value ΔΔCt for each sample. Primer sequences used were: AR-F: 5’ ATG GTG AGC AGA... GTG CCC TAT C 3’ AR- R: 5’ ATG GTC CCT GGC AGT CTC CAA A 3’ PSA-F: CGC AAG TTC ACC CTC AGA AGG T 3’ PSA-R: 5’ GAC GTG ATA CCT TGA AGC ACA CC 3’ MSMB-F...TGG CGT TCC AGG GAC TCA T 3’ Zeb1-F: 5’ GGC ATA CAC CTA CTC AAC TAC GG 3’ Zeb1-R: 5’ TGG GCG GTG TAG AAT CAG AGT C 3’ Snail-F: 5’ TGC CCT CAA GAT

Comparative Transcriptional Analysis of Asexual and Sexual Morphs Reveals Possible Mechanisms in Reproductive Polyphenism of the Cotton Aphid

PubMed Central

Jiang, Feng; Guo, Wei; Zhou, Shu-Tang

2014-01-01

Aphids, the destructive insect pests in the agriculture, horticulture and forestry, are capable of reproducing asexually and sexually upon environmental change. However, the molecular basis of aphid reproductive mode switch remains an enigma. Here we report a comparative analysis of differential gene expression profiling among parthenogenetic females, gynoparae and sexual females of the cotton aphid Aphis gossypii, using the RNA-seq approach with next-generation sequencing platforms, followed by RT-qPCR. At the cutoff criteria of fold change ≥2 and P<0.01, we identified 741 up- and 879 down-regulated genes in gynoparae versus parthenogenetic females, 2,101 up- and 2,210 down-regulated genes in sexual females compared to gynoparae, and 1,614 up- and 2,238 down-regulated genes in sexual females relative to parthenogenetic females. Gene ontology category and KEGG pathway analysis suggest the involvement of differentially expressed genes in multiple cellular signaling pathways into the reproductive mode transition, including phototransduction, cuticle composition, progesterone-mediated oocyte maturation and endocrine regulation. This study forms a basis for deciphering the molecular mechanisms underlying the shift from asexual to sexual reproduction in the cotton aphid. It also provides valuable resources for future studies on this host-alternating aphid species, and the insight into the understanding of reproductive mode plasticity in different aphid species. PMID:24915491

Lineage Selection and the Maintenance of Sex

PubMed Central

de Vienne, Damien M.; Giraud, Tatiana; Gouyon, Pierre-Henri

2013-01-01

Sex predominates in eukaryotes, despite its short-term disadvantage when compared to asexuality. Myriad models have suggested that short-term advantages of sex may be sufficient to counterbalance its twofold costs. However, despite decades of experimental work seeking such evidence, no evolutionary mechanism has yet achieved broad recognition as explanation for the maintenance of sex. We explore here, through lineage-selection models, the conditions favouring the maintenance of sex. In the first model, we allowed the rate of transition to asexuality to evolve, to determine whether lineage selection favoured species with the strongest constraints preventing the loss of sex. In the second model, we simulated more explicitly the mechanisms underlying the higher extinction rates of asexual lineages than of their sexual counterparts. We linked extinction rates to the ecological and/or genetic features of lineages, thereby providing a formalisation of the only figure included in Darwin's “The origin of species”. Our results reinforce the view that the long-term advantages of sex and lineage selection may provide the most satisfactory explanations for the maintenance of sex in eukaryotes, which is still poorly recognized, and provide figures and a simulation website for training and educational purposes. Short-term benefits may play a role, but it is also essential to take into account the selection of lineages for a thorough understanding of the maintenance of sex. PMID:23825582

Sex in an uncertain world: environmental stochasticity helps restore competitive balance between sexually and asexually reproducing populations.

PubMed

Park, A W; Vandekerkhove, J; Michalakis, Y

2014-08-01

Like many organisms, individuals of the freshwater ostracod species Eucypris virens exhibit either obligate sexual or asexual reproductive modes. Both types of individual routinely co-occur, including in the same temporary freshwater pond (their natural habitat in which they undergo seasonal diapause). Given the well-known two-fold cost of sex, this begs the question of how sexually reproducing individuals are able to coexist with their asexual counterparts in spite of such overwhelming costs. Environmental stochasticity in the form of 'false dawn' inundations (where the first hydration is ephemeral and causes loss of early hatching individuals) may provide an advantage to the sexual subpopulation, which shows greater variation in hatching times following inundation. We explore the potential role of environmental stochasticity in this system using life-history data analysis, climate data, and matrix projection models. In the absence of environmental stochasticity, the population growth rate is significantly lower in sexual subpopulations. Climate data reveal that 'false dawn' inundations are common. Using matrix projection modelling with and without environmental stochasticity, we demonstrate that this phenomenon can restore appreciable balance to the system, in terms of population growth rates. This provides support for the role of environmental stochasticity in helping to explain the maintenance of sex and the occurrence of geographical parthenogenesis. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Rgs1 regulates multiple Gα subunits in Magnaporthe pathogenesis, asexual growth and thigmotropism

PubMed Central

Liu, Hao; Suresh, Angayarkanni; Willard, Francis S; Siderovski, David P; Lu, Shen; Naqvi, Naweed I

2007-01-01

Regulators of G-protein signaling (RGS proteins) negatively regulate heterotrimeric G-protein cascades that enable eukaryotic cells to perceive and respond to external stimuli. The rice-blast fungus Magnaporthe grisea forms specialized infection structures called appressoria in response to inductive surface cues. We isolated Magnaporthe RGS1 in a screen for mutants that form precocious appressoria on non-inductive surfaces. We report that a thigmotropic cue is necessary for initiating appressoria and for accumulating cAMP. Similar to an RGS1-deletion strain, magAG187S (RGS-insensitive Gαs) and magAQ208L (GTPase-dead) mutants accumulated excessive cAMP and elaborated appressoria on non-inductive surfaces, suggesting that Rgs1 regulates MagA during pathogenesis. Rgs1 was also found to negatively regulate the Gαi subunit MagB during asexual development. Deficiency of MAGB suppressed the hyper-conidiation defect in RGS1-deletion strain, whereas magBG183S and magBQ204L mutants produced more conidia, similar to the RGS1-deletion strain. Rgs1 physically interacted with GDP·AlF4−-activated forms of MagA, MagB and MagC (a GαII subunit). Thus, Rgs1 serves as a negative regulator of all Gα subunits in Magnaporthe and controls important developmental events during asexual and pathogenic development. PMID:17255942

Characterization of oxylipins and dioxygenase genes in the asexual fungus Aspergillus niger

PubMed Central

2009-01-01

Background Aspergillus niger is an ascomycetous fungus that is known to reproduce through asexual spores, only. Interestingly, recent genome analysis of A. niger has revealed the presence of a full complement of functional genes related to sexual reproduction [1]. An example of such genes are the dioxygenase genes which in Aspergillus nidulans, have been shown to be connected to oxylipin production and regulation of both sexual and asexual sporulation [2-4]. Nevertheless, the presence of sex related genes alone does not confirm sexual sporulation in A. niger. Results The current study shows experimentally that A. niger produces the oxylipins 8,11-dihydroxy octadecadienoic acid (8,11-diHOD), 5,8-dihydroxy octadecadienoic acid (5,8-diHOD), lactonized 5,8-diHOD, 8-hydroxy octadecadienoic acid (8-HOD), 10-hydroxy octadecadienoic acid (10-HOD), small amounts of 8-hydroxy octadecamonoenoic acid (8-HOM), 9-hydroxy octadecadienoic acid (9-HOD) and 13-hydroxy octadecadienoic acid (13-HOD). Importantly, this study shows that the A. niger genome contains three putative dioxygenase genes, ppoA, ppoC and ppoD. Expression analysis confirmed that all three genes are indeed expressed under the conditions tested. Conclusion A. niger produces the same oxylipins and has similar dioxygenase genes as A. nidulans. Their presence could point towards the existence of sexual reproduction in A. niger or a broader role for the gene products in physiology, than just sexual development. PMID:19309517

PfCDPK1 is critical for malaria parasite gametogenesis and mosquito infection

PubMed Central

Bansal, Abhisheka; Molina-Cruz, Alvaro; Brzostowski, Joseph; Liu, Poching; Luo, Yan; Gunalan, Karthigayan; Li, Yuesheng; Ribeiro, José M. C.; Miller, Louis H.

2018-01-01

Efforts to knock out Plasmodium falciparum calcium-dependent protein kinase 1 (PfCDPK1) from asexual erythrocytic stage have not been successful, indicating an indispensable role of the enzyme in asexual growth. We recently reported generation of a transgenic parasite with mutant CDPK1 [Bansal A, et al. (2016) MBio 7:e02011-16]. The mutant CDPK1 (T145M) had reduced activity of transphosphorylation. We reasoned that CDPK1 could be disrupted in the mutant parasites. Consistent with this assumption, CDPK1 was successfully disrupted in the mutant parasites using CRISPR/Cas9. We and others could not disrupt PfCDPK1 in the WT parasites. The CDPK1 KO parasites show a slow growth rate compared with the WT and the CDPK1 T145M parasites. Additionally, the CDPK1 KO parasites show a defect in both male and female gametogenesis and could not establish an infection in mosquitoes. Complementation of the KO parasite with full-length PfCDPK1 partially rescued the asexual growth defect and mosquito infection. Comparative global transcriptomics of WT and the CDPK1 KO schizonts using RNA-seq show significantly high transcript expression of gametocyte-specific genes in the CDPK1 KO parasites. This study conclusively demonstrates that CDPK1 is a good target for developing transmission-blocking drugs. PMID:29311293

PfCDPK1 is critical for malaria parasite gametogenesis and mosquito infection.

PubMed

Bansal, Abhisheka; Molina-Cruz, Alvaro; Brzostowski, Joseph; Liu, Poching; Luo, Yan; Gunalan, Karthigayan; Li, Yuesheng; Ribeiro, José M C; Miller, Louis H

2018-01-23

Efforts to knock out Plasmodium falciparum calcium-dependent protein kinase 1 ( Pf CDPK1) from asexual erythrocytic stage have not been successful, indicating an indispensable role of the enzyme in asexual growth. We recently reported generation of a transgenic parasite with mutant CDPK1 [Bansal A, et al. (2016) MBio 7:e02011-16]. The mutant CDPK1 (T145M) had reduced activity of transphosphorylation. We reasoned that CDPK1 could be disrupted in the mutant parasites. Consistent with this assumption, CDPK1 was successfully disrupted in the mutant parasites using CRISPR/Cas9. We and others could not disrupt Pf CDPK1 in the WT parasites. The CDPK1 KO parasites show a slow growth rate compared with the WT and the CDPK1 T145M parasites. Additionally, the CDPK1 KO parasites show a defect in both male and female gametogenesis and could not establish an infection in mosquitoes. Complementation of the KO parasite with full-length Pf CDPK1 partially rescued the asexual growth defect and mosquito infection. Comparative global transcriptomics of WT and the CDPK1 KO schizonts using RNA-seq show significantly high transcript expression of gametocyte-specific genes in the CDPK1 KO parasites. This study conclusively demonstrates that CDPK1 is a good target for developing transmission-blocking drugs. Copyright © 2018 the Author(s). Published by PNAS.

Antimalarial agents against both sexual and asexual parasites stages: structure-activity relationships and biological studies of the Malaria Box compound 1-[5-(4-bromo-2-chlorophenyl)furan-2-yl]-N-[(piperidin-4-yl)methyl]methanamine (MMV019918) and analogues.

PubMed

Vallone, Alessandra; D'Alessandro, Sarah; Brogi, Simone; Brindisi, Margherita; Chemi, Giulia; Alfano, Gloria; Lamponi, Stefania; Lee, Soon Goo; Jez, Joseph M; Koolen, Karin J M; Dechering, Koen J; Saponara, Simona; Fusi, Fabio; Gorelli, Beatrice; Taramelli, Donatella; Parapini, Silvia; Caldelari, Reto; Campiani, Giuseppe; Gemma, Sandra; Butini, Stefania

2018-04-25

Therapies addressing multiple stages of Plasmodium falciparum life cycle are highly desirable for implementing malaria elimination strategies. MMV019918 (1, 1-[5-(4-bromo-2-chlorophenyl)furan-2-yl]-N-[(piperidin-4-yl)methyl]methanamine) was selected from the MMV Malaria Box for its dual activity against both asexual stages and gametocytes. In-depth structure-activity relationship studies and cytotoxicity evaluation led to the selection of 25 for further biological investigation. The potential transmission blocking activity of 25 versus P. falciparum was confirmed through the standard membrane-feeding assay. Both 1 and 25 significantly prolonged atrioventricular conduction time in Langendorff-isolated rat hearts, and showed inhibitory activity of Ba 2+ current through Ca v 1.2 channels. An in silico target-fishing study suggested the enzyme phosphoethanolamine methyltransferase (PfPMT) as a potential target. However, compound activity against PfPMT did not track with the antiplasmodial activity, suggesting the latter activity relies on a different molecular target. Nevertheless, 25 showed interesting activity against PfPMT, which could be an important starting point for the identification of more potent inhibitors active against both sexual and asexual stages of the parasite. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Convergent acquisition of non-embryonic development in styelid ascidians.

PubMed

Alié, Alexandre; Hiebert, Laurel Sky; Simion, Paul; Scelzo, Marta; Prünster, Maria Mandela; Lotito, Sonia; Delsuc, Frédéric; Douzery, Emmanuel J P; Dantec, Christelle; Lemaire, Patrick; Darras, Sébastien; Kawamura, Kazuo; Brown, Federico D; Tiozzo, Stefano

2018-04-11

Asexual propagation and whole body regeneration are forms of non-embryonic development (NED) widespread across animal phyla and central in life history and evolutionary diversification of metazoans. Whereas it is challenging to reconstruct the gains or losses of NED at large phylogenetic scale, comparative studies could benefit from being conducted at more restricted taxonomic scale, in groups for which phylogenetic relationships are well established. The ascidian family of Styelidae encompasses strictly sexually reproducing solitary forms as well as colonial species that combine sexual reproduction with different forms of NED. To date, the phylogenetic relationships between colonial and solitary styelids remain controversial and so is the pattern of NED evolution. In this study, we built an original pipeline to combine 8 genomes with 18 de novo assembled transcriptomes and constructed datasets of unambiguously orthologous genes. Using a phylogenomic super-matrix of 4,908 genes from these 26 tunicates we provided a robust phylogeny of this family of chordates, which supports two convergent acquisitions of NED. This result prompted us to further describe the budding process in the species Polyandrocarpa zorritensis, leading to the discovery of a novel mechanism of asexual development. While the pipeline and the datasets produced can be used for further phylogenetic reconstructions in tunicates, the phylogeny provided here sets an evolutionary framework for future experimental studies on the emergence and disappearance of complex characters such as asexual propagation and whole body regeneration.

Insight into phagocytosis of mature sexual (gametocyte) stages of Plasmodium falciparum using a human monocyte cell line.

PubMed

Bansal, Geetha P; Weinstein, Corey S; Kumar, Nirbhay

2016-05-01

During natural infection malaria parasites are injected into the bloodstream of a human host by the bite of an infected female Anopheles mosquito. Both asexual and mature sexual stages of Plasmodium circulate in the blood. Asexual forms are responsible for clinical malaria while sexual stages are responsible for continued transmission via the mosquitoes. Immune responses generated against various life cycle stages of the parasite have important roles in resistance to malaria and in reducing malaria transmission. Phagocytosis of free merozoites and erythrocytic asexual stages has been well studied, but very little is known about similar phagocytic clearance of mature sexual stages, which are critical for transmission. We evaluated phagocytic uptake of mature sexual (gametocyte) stage parasites by a human monocyte cell line in the absence of immune sera. We found that intact mature stages do not undergo phagocytosis, unless they are either killed or freed from erythrocytes. In view of this observation, we propose that the inability of mature gametocytes to be phagocytized may actually result in malaria transmission advantage. On the other hand, mature gametocytes that are not transmitted to mosquitoes during infection will eventually die and undergo phagocytosis, initiating immune responses that may have transmission blocking potential. A better understanding of early phagocytic clearance and immune responses to gametocytes may identify additional targets for transmission blocking strategies. Copyright © 2016 Elsevier B.V. All rights reserved.

Sexual Plasticity and Self-Fertilization in the Sea Anemone Aiptasia diaphana

PubMed Central

Schlesinger, Ami; Kramarsky-Winter, Esti; Rosenfeld, Hanna; Armoza-Zvoloni, Rachel; Loya, Yossi

2010-01-01

Traits that influence reproductive success and contribute to reproductive isolation in animal and plant populations are a central focus of evolutionary biology. In the present study we used an experimental approach to demonstrate the occurrence of environmental effects on sexual and asexual reproduction, and provide evidence for sexual plasticity and inter-clonal fertilization in laboratory-cultured lines of the sea anemone Aiptasia diaphana. We showed that in A. diaphana, both asexual reproduction by pedal laceration, and sexual reproduction have seasonal components. The rate of pedal laceration was ten-fold higher under summer photoperiod and water temperature conditions than under winter conditions. The onset of gametogenesis coincided with the rising water temperatures occurring in spring, and spawning occurred under parameters that emulated summer photoperiod and temperature conditions. In addition, we showed that under laboratory conditions, asexually produced clones derived from a single founder individual exhibit sexual plasticity, resulting in the development of both male and female individuals. Moreover, a single female founder produced not only males and females but also hermaphrodite individuals. We further demonstrated that A. diaphana can fertilize within and between clone lines, producing swimming planula larvae. These diverse reproductive strategies may explain the species success as invader of artificial marine substrates. We suggest that these diverse reproductive strategies, together with their unique evolutionary position, make Aiptasia diaphana an excellent model for studying the evolution of sex. PMID:20686700

Expansion of Genes Encoding piRNA-Associated Argonaute Proteins in the Pea Aphid: Diversification of Expression Profiles in Different Plastic Morphs

PubMed Central

Lu, Hsiao-ling; Tanguy, Sylvie; Rispe, Claude; Gauthier, Jean-Pierre; Walsh, Tom; Gordon, Karl; Edwards, Owain; Tagu, Denis; Chang, Chun-che; Jaubert-Possamai, Stéphanie

2011-01-01

Piwi-interacting RNAs (piRNAs) are known to regulate transposon activity in germ cells of several animal models that propagate sexually. However, the role of piRNAs during asexual reproduction remains almost unknown. Aphids that can alternate sexual and asexual reproduction cycles in response to seasonal changes of photoperiod provide a unique opportunity to study piRNAs and the piRNA pathway in both reproductive modes. Taking advantage of the recently sequenced genome of the pea aphid Acyrthosiphon pisum, we found an unusually large lineage-specific expansion of genes encoding the Piwi sub-clade of Argonaute proteins. In situ hybridisation showed differential expressions between the duplicated piwi copies: while Api-piwi2 and Api-piwi6 are “specialised” in germ cells their most closely related copy, respectively Api-piwi5 and Api-piwi3, are expressed in the somatic cells. The differential expression was also identified in duplicated ago3: Api-ago3a in germ cells and Api-ago3b in somatic cells. Moreover, analyses of expression profiles of the expanded piwi and ago3 genes by semi-quantitative RT-PCR showed that expressions varied according to the reproductive types. These specific expression patterns suggest that expanded aphid piwi and ago3 genes have distinct roles in asexual and sexual reproduction. PMID:22162754

Superclone Expansion, Long-Distance Clonal Dispersal and Local Genetic Structuring in the Coral Pocillopora damicornis Type β in Reunion Island, South Western Indian Ocean.

PubMed

Gélin, Pauline; Fauvelot, Cécile; Mehn, Vincent; Bureau, Sophie; Rouzé, Héloïse; Magalon, Hélène

2017-01-01

The scleractinian coral Pocillopora damicornis type β is known to present a mixed reproduction mode: through sexual reproduction, new genotypes are created, while asexual reproduction insures their propagation. In order to investigate the relative proportion of each reproduction mode in P. damicornis type β populations from Reunion Island, Indian Ocean, clonal propagation along the west coast was assessed through four sampling sites with increasing geographical distance between sites. Coral colonies were sampled either exhaustively, randomly or haphazardly within each site, and genotypic diversity was assessed using 13 microsatellite loci over a total of 510 P. damicornis type β determined a posteriori from their mtDNA haplotype (a 840 bp sequenced fragment of the Open Reading Frame). Overall, 47% of all the sampled colonies presented the same multi-locus genotype (MLG), a superclone, suggesting that asexual propagation is extremely important in Reunion Island. Within each site, numerous MLGs were shared by several colonies, suggesting local clonal propagation through fragmentation. Moreover, some of these MLGs were found to be shared among several sites located 40 km apart. While asexual reproduction by fragmentation seems unlikely over long distances, our results suggest a production of parthenogenetic larvae. Despite shared MLGs, two differentiated clusters were enclosed among populations of the west coast of Reunion Island, revealing the necessity to set up appropriate managing strategies at a local scale.

Bone Marrow Is a Major Parasite Reservoir in Plasmodium vivax Infection

PubMed Central

2018-01-01

ABSTRACT Plasmodium vivax causes heavy burdens of disease across malarious regions worldwide. Mature P. vivax asexual and transmissive gametocyte stages occur in the blood circulation, and it is often assumed that accumulation/sequestration in tissues is not an important phase in their development. Here, we present a systematic study of P. vivax stage distributions in infected tissues of nonhuman primate (NHP) malaria models as well as in blood from human infections. In a comparative analysis of the transcriptomes of P. vivax and Plasmodium falciparum blood-stage parasites, we found a conserved cascade of stage-specific gene expression despite the greatly different gametocyte maturity times of these two species. Using this knowledge, we validated a set of conserved asexual- and gametocyte-stage markers both by quantitative real-time PCR and by antibody assays of peripheral blood samples from infected patients and NHP (Aotus sp.). Histological analyses of P. vivax parasites in organs of 13 infected NHP (Aotus and Saimiri species) demonstrated a major fraction of immature gametocytes in the parenchyma of the bone marrow, while asexual schizont forms were enriched to a somewhat lesser extent in this region of the bone marrow as well as in sinusoids of the liver. These findings suggest that the bone marrow is an important reservoir for gametocyte development and proliferation of malaria parasites. PMID:29739900

Convergent Acquisition of Nonembryonic Development in Styelid Ascidians

PubMed Central

Alié, Alexandre; Hiebert, Laurel Sky; Simion, Paul; Scelzo, Marta; Prünster, Maria Mandela; Lotito, Sonia; Delsuc, Frédéric; Douzery, Emmanuel J P; Dantec, Christelle; Lemaire, Patrick; Darras, Sébastien; Kawamura, Kazuo; Brown, Federico D; Tiozzo, Stefano

2018-01-01

Abstract Asexual propagation and whole body regeneration are forms of nonembryonic development (NED) widespread across animal phyla and central in life history and evolutionary diversification of metazoans. Whereas it is challenging to reconstruct the gains or losses of NED at large phylogenetic scale, comparative studies could benefit from being conducted at more restricted taxonomic scale, in groups for which phylogenetic relationships are well established. The ascidian family of Styelidae encompasses strictly sexually reproducing solitary forms as well as colonial species that combine sexual reproduction with different forms of NED. To date, the phylogenetic relationships between colonial and solitary styelids remain controversial and so is the pattern of NED evolution. In this study, we built an original pipeline to combine eight genomes with 18 de novo assembled transcriptomes and constructed data sets of unambiguously orthologous genes. Using a phylogenomic super-matrix of 4,908 genes from these 26 tunicates we provided a robust phylogeny of this family of chordates, which supports two convergent acquisitions of NED. This result prompted us to further describe the budding process in the species Polyandrocarpa zorritensis, leading to the discovery of a novel mechanism of asexual development. Whereas the pipeline and the data sets produced can be used for further phylogenetic reconstructions in tunicates, the phylogeny provided here sets an evolutionary framework for future experimental studies on the emergence and disappearance of complex characters such as asexual propagation and whole body regeneration. PMID:29660002

The effects of verapamil and diltiazem on N-, P- and Q-type calcium channels mediating dopamine release in rat striatum

PubMed Central

Dobrev, Dobromir; Milde, Alexander S; Andreas, Klaus; Ravens, Ursula

1999-01-01

The putative inhibitory effects of verapamil and diltiazem on neuronal non-L-type Ca2+ channels were studied by investigating their effects on either K+- or veratridine-evoked [3H]-dopamine ([3H]-DA) release in rat striatal slices. Involvement of N-, P- and Q-type channels was identified by sensitivity of [3H]-DA release to ω-conotoxin GVIA (ω-CTx-GVIA), ω-agatoxin IVA (ω-Aga-IVA) and ω-conotoxin MVIIC (ω-CTx-MVIIC), respectively.KCl (50 mM)-evoked [3H]-DA release was abolished in the absence of Ca2+, and was insensitive to dihydropyridines (up to 30 μM). It was significantly blocked by ω-CTx-GVIA (1 μM), ω-Aga-IVA (30 nM) and was confirmed to be abolished by ω-CTx-MVIIC (3 μM), indicating involvement of N-, P- and Q-type channel subtypes.Verapamil and diltiazem inhibited K+-evoked [3H]-DA release in a concentration-dependent manner. The inhibitory effects of verapamil or diltiazem (each 30 μM) were fully additive to the effect of ω-CTx-GVIA (1 μM), whereas co-application with ω-Aga-IVA (30 nM) produced similar effects to those of ω-Aga-IVA alone.As shown previously, veratridine-evoked [3H]-DA release in Ca2+ containing medium exclusively involves Q-type Ca2+ channels. Here, diltiazem (30 μM) did not inhibit veratridine-evoked [3H]-DA release, whereas verapamil (30 μM) partially inhibited it, indicating possible involvement of Q-type channels in verapamil-induced inhibition. However, verapamil (30 μM) inhibited this release even in the absence of extracellular Ca2+, suggesting that Na+ rather than Q-type Ca2+ channels are involved.Taken together, our results suggest that verapamil can block P- and at higher concentrations possibly N- and Q-type Ca2+ channels linked to [3H]-DA release, whereas diltiazem appears to block P-type Ca2+ channels only. PMID:10385261

Birth-weight, insulin levels, and HOMA-IR in newborns at term.

PubMed

Simental-Mendía, Luis E; Castañeda-Chacón, Argelia; Rodríguez-Morán, Martha; Guerrero-Romero, Fernando

2012-07-07

Recent studies have demonstrated that low and high birth-weight at birth are risk factors of developing diabetes. The aim of this study was to determine if the abnormal birth-weight is related with hyperinsulinemia and elevated index of the Homeostasis Model assessment for Insulin Resistance (HOMA-IR) at birth, in at term newborns. Newborns with gestational age between 38 and 41 weeks, products of normal pregnancies of healthy mothers aged 18 to 39 years, were eligible to participate. Small-for-gestational age (SGA) and large-for-gestational age (LGA) newborns were compared with appropriate-for-gestational (AGA) age newborns. Incomplete or unclear data about mother's health status, diabetes, gestational diabetes, history of gestational diabetes, hypertension, pre-eclampsia, eclampsia, and other conditions that affect glucose metabolism were exclusion criteria. Hyperinsulinemia was defined by serum insulin levels ≥13.0 μU/mL and IR by HOMA-IR ≥2.60. Multiple logistic regression analysis was used to determine the odds ratio (OR) that computes the association between birth-weight (independent variable) with hyperinsulinemia and HOMA-IR index (dependent variables). A total of 107 newborns were enrolled; 13, 22, and 72 with SGA, LGA, and AGA, respectively. Hyperinsulinemia was identified in 2 (15.4%), 6 (27.3%), and 5 (6.9%) with SGA, LGA, and AGA (p=0.03), whereas IR in 3 (23.1%), 8 (36.4%), and 10 (13.9%) newborns with SGA, LGA and AGA (p=0.06). The LGA showed a strong association with hyperinsulinemia (OR 5.02; CI 95%, 1.15-22.3; p=0.01) and HOMA-IR (OR 3.54; CI 95%, 1.03-12.16; p=0.02); although without statistical significance, the SGA showed a tendency of association with hyperinsulinemia (OR 2.43; CI 95%, 0.43-17.3 p=0.29) and HOMA-IR (OR 1.86; CI 95%, 0.33-9.37; p=0.41). Our results suggest that LGA is associated with hyperinsulinemia and elevated HOMA-IR at birth whereas the SGA show a tendency of association.

Low Birthweight Increases the Likelihood of Severe Steatosis in Pediatric Non-Alcoholic Fatty Liver Disease.

PubMed

Bugianesi, Elisabetta; Bizzarri, Carla; Rosso, Chiara; Mosca, Antonella; Panera, Nadia; Veraldi, Silvio; Dotta, Andrea; Giannone, Germana; Raponi, Massimiliano; Cappa, Marco; Alisi, Anna; Nobili, Valerio

2017-08-01

Small for gestational age (SGA) is associated with an increased risk of non-alcoholic fatty liver disease (NAFLD). Our aim was to investigate the correlation of birthweight with the severity of liver damage in a large cohort of children with NAFLD. Two hundred and eighty-eight consecutive Caucasian Italian overweight/obese children with biopsy-proven NAFLD were included in the study. We examined the relative association of each histological feature of NAFLD with metabolic alterations, insulin-resistance, I148M polymorphism in the patatin-like phospholipase domain-containing protein 3 (PNPLA3) gene, and birthweight relative to gestational age. In the whole NAFLD cohort, 12.2% of patients were SGA, 62.8% appropriate for gestational age (AGA), and 25% large for gestational age (LGA). SGA children had a higher prevalence of severe steatosis (69%) and severe portal inflammation (14%) compared with the AGA and LGA groups. Notably, severe steatosis (>66%) was decreasing from SGA to AGA and LGA, whereas the prevalence of moderate steatosis (33-66%) was similar in three groups. The prevalence of type 1 NAFLD is higher in the LGA group with respect to the other two groups (25% vs.5.2% vs.9.4%), whereas the SGA group shows a higher prevalence of overlap type (85.8%) with respect to the LGA group (51.4%) but not compared with the AGA group (75%). At multivariable regression analysis, SGA at birth increased fourfold the likelihood of severe steatosis (odds ratio (OR) 4.0, 95% confidence interval (CI) 1.43-10.9, P=0.008) and threefold the likelihood of NAFLD Activity Score (NAS)≥5 (OR 2.98, 95% CI 1.06-8.33, P=0.037) independently of homeostasis model assessment of insulin resistance and PNPLA3 genotype. The PNPLA3-CC wild-type genotype was the strongest independent predictor of the absence of significant fibrosis (OR 0.26, 95% CI 0.13-0.52, P=<0.001). In children with NAFLD, the risk of severe steatosis is increased by SGA at birth, independent of and in addition to other powerful risk factors (insulin-resistance and I148M variant of the PNPLA3 gene).

Plant germline formation: common concepts and developmental flexibility in sexual and asexual reproduction.

PubMed

Schmidt, Anja; Schmid, Marc W; Grossniklaus, Ueli

2015-01-15

The life cycle of flowering plants alternates between two heteromorphic generations: a diploid sporophytic generation and a haploid gametophytic generation. During the development of the plant reproductive lineages - the germlines - typically, single sporophytic (somatic) cells in the flower become committed to undergo meiosis. The resulting spores subsequently develop into highly polarized and differentiated haploid gametophytes that harbour the gametes. Recent studies have provided insights into the genetic basis and regulatory programs underlying cell specification and the acquisition of reproductive fate during both sexual reproduction and asexual (apomictic) reproduction. As we review here, these recent advances emphasize the importance of transcriptional, translational and post-transcriptional regulation, and the role of epigenetic regulatory pathways and hormonal activity. © 2015. Published by The Company of Biologists Ltd.

The effect of sulphadoxine/pyrimethamine on gametocytes in falciparum malaria.

PubMed

Ittiravivongs, A; Vasuvat, C; Kongrod, S

1984-09-01

A study of the effect of sulphadoxine/pyrimethamine (Fansidar) on P. falciparum's gametocytes in peripheral blood was carried out in Western Thailand. One group of 77 patients with asexual form P. falciparum sensitive to Fansidar were followed weekly to detect the appearance and the duration of gametocytes in peripheral blood after Fansidar treatment on the basis of thick blood film examination. Another group of 14 patients with sexual form P. falciparum was not given any antimalarial treatment and also followed up weekly. No significant difference of average duration of detectable gametocytes was observed between the groups. The average number of days that gametocytes appeared after asexual form in patients receiving treatment was the same as in the untreated group. It is unlikely that Fansidar has the stimulating effect on gametocytogenesis as previously reported.

Trade-offs drive resource specialization and the gradual establishment of ecotypes

PubMed Central

2014-01-01

Background Speciation is driven by many different factors. Among those are trade-offs between different ways an organism utilizes resources, and these trade-offs can constrain the manner in which selection can optimize traits. Limited migration among allopatric populations and species interactions can also drive speciation, but here we ask if trade-offs alone are sufficient to drive speciation in the absence of other factors. Results We present a model to study the effects of trade-offs on specialization and adaptive radiation in asexual organisms based solely on competition for limiting resources, where trade-offs are stronger the greater an organism’s ability to utilize resources. In this model resources are perfectly substitutable, and fitness is derived from the consumption of these resources. The model contains no spatial parameters, and is therefore strictly sympatric. We quantify the degree of specialization by the number of ecotypes evolved and the niche breadth of the population, and observe that these are sensitive to resource influx and trade-offs. Resource influx has a strong effect on the degree of specialization, with a clear transition between minimal diversification at high influx and multiple species evolving at low resource influx. At low resource influx the degree of specialization further depends on the strength of the trade-offs, with more ecotypes evolving the stronger trade-offs are. The specialized organisms persist through negative frequency-dependent selection. In addition, by analyzing one of the evolutionary radiations in greater detail we demonstrate that a single mutation alone is not enough to establish a new ecotype, even though phylogenetic reconstruction identifies that mutation as the branching point. Instead, it takes a series of additional mutations to ensure the stable coexistence of the new ecotype in the background of the existing ones. Conclusions Trade-offs are sufficient to drive the evolution of specialization in sympatric asexual populations. Without trade-offs to restrain traits, generalists evolve and diversity decreases. The observation that several mutations are required to complete speciation, even when a single mutation creates the new species, highlights the gradual nature of speciation and the importance of phyletic evolution. PMID:24885598

40 CFR 98.474 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... American National Standards Institute (ANSI), the American Gas Association (AGA), the American Society of... Standards and Technology (NIST) traceable. (c) General. (1) If you measure the concentration of any CO2...

Clinical utility and validity of minoxidil response testing in androgenetic alopecia.

PubMed

Goren, Andy; Shapiro, Jerry; Roberts, Janet; McCoy, John; Desai, Nisha; Zarrab, Zoulikha; Pietrzak, Aldona; Lotti, Torello

2015-01-01

Clinical response to 5% topical minoxidil for the treatment of androgenetic alopecia (AGA) is typically observed after 3-6 months. Approximately 40% of patients will regrow hair. Given the prolonged treatment time required to elicit a response, a diagnostic test for ruling out nonresponders would have significant clinical utility. Two studies have previously reported that sulfotransferase enzyme activity in plucked hair follicles predicts a patient's response to topical minoxidil therapy. The aim of this study was to assess the clinical utility and validity of minoxidil response testing. In this communication, the present authors conducted an analysis of completed and ongoing studies of minoxidil response testing. The analysis confirmed the clinical utility of a sulfotransferase enzyme test in successfully ruling out 95.9% of nonresponders to topical minoxidil for the treatment of AGA. © 2014 Wiley Periodicals, Inc.

Increasing transcultural awareness: the McMaster-Aga Khan-CIDA Project workshop model.

PubMed

Smith, S E

1997-01-01

McMaster-Aga Khan-CIDA Project personnel at McMaster University School of Nursing over a period of four years designed and conducted eight one-day introductory workshops for nurses, faculty, staff, host families, and others involved with Pakistani nurses and Lady Health Visitors studying in Canada. The workshops (entitled Increasing Intercultural Awareness) assisted the Canadian and international participants to improve their awareness and knowledge of transcultural communication in preparation for working and socializing together. Using a participatory and active-learning approach, the workshop method introduced participants to transcultural communication; emphasized appreciation of cultural values, similarities and differences; and provided country-specific information on Pakistan. This article outlines the workshop design and rationale and describes specific examples of the transcultural nursing principles, practices, and teaching activities included in the one-day event.

Structural stability, electronic structure and mechanical properties of alkali gallium hydrides AGaH{sub 4} (A = Li, Na)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santhosh, M.; Rajeswarapalanichamy, R., E-mail: rrpalanichamy@gmail.com; Manikandan, M.

2016-05-06

Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of alkali gallium hydrides AGaH{sub 4} (A = Li, Na) for three different crystal structures, namely tetragonal (P42{sub 1}c), tetragonal (P4{sub 2}/nmc) and monoclinic (P2{sub 1}/c). Among the considered structures, tetragonal (P42{sub 1}c) phase is found to be the most stable phase for these hydrides at normal pressure. A pressure induced structural phase transition from tetragonal (P42{sub 1}c) to tetragonal (P4{sub 2}/nmc) is observed. The electronic structure reveals that these hydrides are insulators. The calculated elastic constants indicate that these ternary imides are mechanically stablemore » at normal pressure.« less

Body water content of extremely preterm infants at birth

PubMed Central

Hartnoll, G.; Betremieux, P.; Modi, N.

2000-01-01

BACKGROUND—Preterm birth is often associated with impaired growth. Small for gestational age status confers additional risk.
AIM—To determine the body water content of appropriately grown (AGA) and small for gestational age (SGA) preterm infants in order to provide a baseline for longitudinal studies of growth after preterm birth.
METHODS—All infants born at the Hammersmith and Queen Charlotte's Hospitals between 25 and 30 weeks gestational age were eligible for entry into the study. Informed parental consent was obtained as soon after delivery as possible, after which the extracellular fluid content was determined by bromide dilution and total body water by H218O dilution.
RESULTS—Forty two preterm infants were studied. SGA infants had a significantly higher body water content than AGA infants (906 (833-954) and 844 (637-958) ml/kg respectively; median (range); p = 0.019). There were no differences in extracellular and intracellular fluid volumes, nor in the ratio of extracellular to intracellular fluid. Estimates of relative adiposity suggest a body fat content of about 7% in AGA infants, assuming negligible fat content in SGA infants and lean body tissue hydration to be equivalent in the two groups.
CONCLUSIONS—Novel values for the body water composition of the SGA preterm infant at 25-30 weeks gestation are presented. The data do not support the view that SGA infants have extracellular dehydration, nor is their regulation of body water impaired.

 PMID:10873174

Similar Response Patterns to 5%Topical Minoxidil Foam in Frontal and Vertex Scalp of Men with Androgenetic Alopecia: A Microarray Analysis

PubMed Central

Mirmirani, P.; Consolo, M.; Oyetakin-White, P.; Baron, E.; Leahy, P.; Karnik, P.

2014-01-01

Summary Background There are regional variations in scalp hair miniaturization seen in androgenetic alopecia (AGA). Use of topical minoxidil can lead to reversal of miniaturization in the vertex scalp. However, its effects on other scalp regions are less well studied. Methods A placebo controlled double-blinded prospective pilot study of minoxidil topical foam 5% (MTF) vs placebo was conducted in sixteen healthy men ages 18-49 with Hamilton-Norwood type IV-V thinning. The subjects were asked to apply the treatment (active drug or placebo) to the scalp twice daily for eight weeks. Stereotactic scalp photographs were taken at the baseline and final visits to monitor global hair growth. Scalp biopsies were done at the leading edge of hair loss from the frontal and vertex scalp before and after treatment with MTF and placebo and microarray analysis was done using the Affymetrix GeneChip HG U133 Plus 2.0. Results Global stereotactic photographs showed that MTF induced hair growth in both the frontal and vertex scalp of AGA patients. Regional differences in gene expression profiles were observed before treatment. However, MTF treatment induced the expression of hair keratin associated genes and decreased the expression of epidermal differentiation complex (EDC) and inflammatory genes in both scalp regions. Conclusions These data suggest that MTF is effective in the treatment of both the frontal and vertex scalp of AGA patients. PMID:25204361

Efficacy and Safety of Minoxidil 5% Foam in Combination With a Botanical Hair Solution in Men With Androgenic Alopecia.

PubMed

Keaney, Terrence C; Pham, Hanh; von Grote, Erika; Meckfessel, Matthew H

2016-04-01

Androgenic alopecia (AGA) is the most common type of hair loss in men, characterized by hair miniaturization, hairline recession, and vertex balding. It affects approximately 50% of men, negatively affecting self-esteem and sociability. Topical minoxidil formulations are approved up to a 5% concentration for men, but patient adherence to treatment is challenged by gradual results that may be perceived as a lack of initial benefit. Herbal extracts, which are also believed to promote healthier-looking hair, have a long history of use in hair care formulations. The safety and efficacy of a twice-daily regimen of 5% minoxidil foam used in combination with a novel botanical hair solution was evaluated in a 12-week, multicenter, single-arm, open label study in 56 subjects with mild to moderate AGA. Assessments included investigator ratings of improvement and subject self-ratings of satisfaction. Investigator ratings indicated significant improvement in scalp hair coverage and perception of overall treatment benefit in as early as 4 weeks (P<.001). Subject self-ratings were significant for improved hair growth and hair appearance in as few as 4 weeks (P<.05). The regimen was well tolerated, and subjects indicated a high degree of satisfaction. Investigator and subject-assessed efficacy and subject satisfaction with this novel regimen provide clinicians with an effective treatment option for AGA that also provides a high level of patient satisfaction, which may help promote patient adherence to long-term treatment.

Two euAGAMOUS Genes Control C-Function in Medicago truncatula

PubMed Central

Gómez-Mena, Concepción; Constantin, Gabriela D.; Wen, Jiangqi; Mysore, Kirankumar S.; Lund, Ole S.; Johansen, Elisabeth; Beltrán, José Pío; Cañas, Luis A.

2014-01-01

C-function MADS-box transcription factors belong to the AGAMOUS (AG) lineage and specify both stamen and carpel identity and floral meristem determinacy. In core eudicots, the AG lineage is further divided into two branches, the euAG and PLE lineages. Functional analyses across flowering plants strongly support the idea that duplicated AG lineage genes have different degrees of subfunctionalization of the C-function. The legume Medicago truncatula contains three C-lineage genes in its genome: two euAG genes (MtAGa and MtAGb) and one PLENA-like gene (MtSHP). This species is therefore a good experimental system to study the effects of gene duplication within the AG subfamily. We have studied the respective functions of each euAG genes in M. truncatula employing expression analyses and reverse genetic approaches. Our results show that the M. truncatula euAG- and PLENA-like genes are an example of subfunctionalization as a result of a change in expression pattern. MtAGa and MtAGb are the only genes showing a full C-function activity, concomitant with their ancestral expression profile, early in the floral meristem, and in the third and fourth floral whorls during floral development. In contrast, MtSHP expression appears late during floral development suggesting it does not contribute significantly to the C-function. Furthermore, the redundant MtAGa and MtAGb paralogs have been retained which provides the overall dosage required to specify the C-function in M. truncatula. PMID:25105497

Endothelial progenitor cells in mothers of low-birthweight infants: a link between defective placental vascularization and increased cardiovascular risk?

PubMed

King, Thomas F J; Bergin, David A; Kent, Etaoin M; Manning, Fiona; Reeves, Emer P; Dicker, Patrick; McElvaney, Noel G; Sreenan, Seamus; Malone, Fergal D; McDermott, John H

2013-01-01

Offspring birthweight is inversely associated with future maternal cardiovascular mortality, a relationship that has yet to be fully elucidated. Endothelial progenitor cells (EPCs) are thought to play a key role in vasculogenesis, and EPC numbers reflect cardiovascular risk. Our objective was to ascertain whether EPC number or function was reduced in mothers of low-birthweight infants. This was a prospective cohort study in a general antenatal department of a university maternity hospital. Twenty-three mothers of small for gestational age (SGA) infants (birthweight < 10th centile) and 23 mothers of appropriate for gestational age (AGA) infants (birthweight ≥ 10th centile) were recruited. Maternal EPC number and function, conventional cardiovascular risk markers, and cord blood adiponectin were measured. Median EPC count was lower (294 vs. 367, P = 0.005) and EPC migration was reduced (0.91 vs. 1.59, P < 0.001) in SGA compared with AGA infants, with no difference in EPC adhesion (0.221 vs. 0.284 fluorescence units, P = 0.257). Maternal triglyceride levels were higher in SGA than AGA infants (0.98 vs. 0.78 mmol/liter, P = 0.006), but there was no difference in cholesterol, glucose, insulin, glycosylated hemoglobin, adiponectin, or blood pressure. There was a moderate monotone (increasing) relationship between birthweight and umbilical cord blood adiponectin (r = 0.475, P = 0.005). Giving birth to an SGA infant was associated with lower maternal EPC number and reduced migratory function. Cord blood adiponectin was significantly correlated with birthweight.

Topical valproic acid increases the hair count in male patients with androgenetic alopecia: a randomized, comparative, clinical feasibility study using phototrichogram analysis.

PubMed

Jo, Seong Jin; Shin, Hyoseung; Park, Young Woon; Paik, Seung Hwan; Park, Won Seok; Jeong, Yeon Su; Shin, Hong Ju; Kwon, Ohsang

2014-04-01

Valproic acid (VPA), a widely used anticonvulsant, inhibits glycogen synthase kinase 3β and activates the Wnt/β-catenin pathway, which is associated with hair growth cycle and anagen induction. To assess the efficacy of topical VPA for treating androgenetic alopecia (AGA), we performed a randomized, double-blind, placebo-controlled clinical trial. Male patients with moderate AGA underwent treatment with either VPA (sodium valproate, 8.3%) or placebo spray for 24 weeks. The primary end-point for efficacy was the change in hair count during treatment, which was assessed by phototrichogram analysis. Of the 40 patients enrolled in the study, 27 (n = 15, VPA group; n = 12, placebo group) completed the entire protocol with good compliance. No statistical differences in age, hair loss duration and total hair count at baseline were found between the groups. The mean change in total hair count was significantly higher in the VPA group than in the placebo group (P = 0.047). Both groups experienced mostly mild and self-limited adverse events, but their differences in prevalence rates were similar between the two groups (P = 0.72). A subject treated with topical VPA developed ventricular tachycardia, but it did not seem to be related to the VPA spray. Topical VPA increased the total hair counts of our patients; therefore, it is a potential treatment option for AGA. © 2014 Japanese Dermatological Association.

Oral Finasteride Presents With Sexual-Unrelated Withdrawal in Long-Term Treated Androgenic Alopecia in Men.

PubMed

Perez-Mora, Nicolas; Velasco, Carlos; Bermüdez, Fernando

2015-01-01

Side effects associated with oral finasteride (FT) (1 mg/d) and topical 5% minoxidil (M5) have been previously described. The authors have evaluated long-term adverse effects and causes of long-term therapy withdrawal in patients with androgenic alopecia (AGA) treated with M5+FT vs M5 without FT. A total of 130 AGA patients with a minimum 2-year follow-up volunteered to complete a questionnaire on side effects. Patients' responses were classified as "never," "rarely," "sometimes," "often," and "all the time." An adverse effect was considered in the presence of an "often" or "all the time" response. A total of 100 patients received combined M5+FT and were compared with 30 patients receiving single-therapy M5 according to the physician's clinical criteria. Erectile dysfunction (3%), diminished libido (4%), and reduced ejaculation (7%) were present in patients taking M5+FT but were absent in patients taking M5. Only 1 of 100 patients taking M5+FT quit long-term therapy due to sexual adverse effects (diminished libido). The main causes for therapy withdrawal in the FT group were lack of positive results in 11% and in the M5 group side effects in 4% (P < .02). Increased body hair was different between groups: with 6.6% in the M5 group and 4% in the M5+FT group (P < .03). FT demonstrates sexual-unrelated reasons as the main cause of therapy withdrawal in long-term treated AGA patients.

Lifestyle Factors in Late Adolescence Associate With Later Development of Diverticular Disease Requiring Hospitalization.

PubMed

Järbrink-Sehgal, M Ellionore; Schmidt, Peter T; Sköldberg, Filip; Hemmingsson, Tomas; Hagström, Hannes; Andreasson, Anna

2018-04-12

The burden of diverticular disease on society is high and is increasing with an aging population. It is therefore important to identify risk factors for disease development or progression. Many lifestyle behaviors during adolescence affect risk for later disease. We searched for adolescent lifestyle factors that affect risk of diverticular disease later in life. We performed a retrospective analysis of data from 43,772 men (age, 18-20 y) conscripted to military service in Sweden from 1969 through 1970, with a follow-up period of 39 years. All conscripts underwent an extensive mental and physical health examination and completed questionnaires covering alcohol consumption, smoking, and use of recreational drugs; cardiovascular fitness was assessed using an ergometer cycle at the time of conscription. Outcome data were collected from national registers to identify discharge diagnoses of diverticular disease until the end of 2009. We performed Cox regression analysis to determine whether body mass index, cardiovascular fitness, smoking, use of recreational drugs, alcohol consumption, and risky use of alcohol, at time of conscription are independent risk factors for development of diverticular disease. Overweight and obese men had a 2-fold increased risk of diverticular disease compared to normal-weight men (hazard ratio, 2.00; P < .001). A high level of cardiovascular fitness was associated with a reduced risk of diverticular disease requiring hospitalization (P = .009). Smoking (P = .003), but not use of recreational drugs (P = .11), was associated with an increased risk of diverticular disease requiring hospitalization. Risky use of alcohol, but not alcohol consumption per se, was associated with a 43% increase in risk of diverticular disease requiring hospitalization (P = .007). In a retrospective analysis of data from 43,772 men in Sweden, we associated being overweight or obese, a smoker, a high-risk user of alcohol, and/or having a low level of cardiovascular fitness in late adolescence with an increased risk of developing diverticular disease requiring hospitalization later in life. Improving lifestyle factors among adolescents might reduce the economic burden of diverticular disease decades later. Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.

Activity of Herbal Medicines on Plasmodium falciparum Gametocytes: Implications for Malaria Transmission in Ghana

PubMed Central

Amoah, Linda Eva; Kakaney, Courage; Kwansa-Bentum, Bethel; Kusi, Kwadwo Asamoah

2015-01-01

Background Malaria still remains a major health issue in Ghana despite the introduction of Artemisinin-based combination therapy (ACT) coupled with other preventative measures such as the use of insecticide treated nets (ITNs). The global quest for eradication of malaria has heightened the interest of identifying drugs that target the sexual stage of the parasite, referred to as transmission-blocking drugs. This study aimed at assessing the efficacy and gametocydal effects of some commonly used herbal malaria products in Ghana. Methodology/Principal Findings After identifying herbal anti-malarial products frequently purchased on the Ghanaian market, ten of them were selected and lyophilized. In vitro drug sensitivity testing of different concentrations of the herbal products was carried out on asexual and in vitro generated gametocytes of the 3D7 strain of Plasmodium falciparum. The efficacies of the products were assessed by microscopy. Cultures containing low dose of RT also produced the least number of late stage gametocytes. Two of the herbal products CM and RT inhibited the growth of late stage gametocytes by > 80% at 100 μg/ml whilst KG was the most inhibitory to early stage gametocytes at that same concentration. However at 1 μg/ml, only YF significantly inhibited the survival of late stage gametocytes although at that same concentration YF barely inhibited the survival of early stage gametocytes. Conclusions/Significance Herbal product RT (Aloe schweinfurthii, Khaya senegalensis, Piliostigma thonningii and Cassia siamea) demonstrated properties of a highly efficacious gametocydal product. Low dose of herbal product RT exhibited the highest gametocydal activity and at 100 μg/ml, RT exhibited >80% inhibition of late stage gametocytes. However inhibition of asexual stage parasite by RT was not optimal. Improving the asexual inhibition of RT could convert RT into an ideal antimalarial herbal product. We also found that generally C. sanguinolenta containing herbal products exhibited gametocydal activity in addition to high asexual efficacy. Herbal products with high gametocydal activity can help in the fight to reduce malaria transmission. PMID:26562778

Resilience of Zostera muelleri seagrass to small-scale disturbances: the relative importance of asexual versus sexual recovery

PubMed Central

Macreadie, Peter I; York, Paul H; Sherman, Craig DH

2014-01-01

Resilience is the ability of an ecosystem to recover from disturbance without loss of essential function. Seagrass ecosystems are key marine and estuarine habitats that are under threat from a variety of natural and anthropogenic disturbances. The ability of these ecosystems to recovery from disturbance will to a large extent depend on the internsity and scale of the disturbance, and the relative importance of sexual versus asexual reproduction within populations. Here, we investigated the resilience of Zostera muelleri seagrass (Syn. Zostera capricorni) to small-scale disturbances at four locations in Lake Macquarie – Australia's largest coastal lake – and monitored recovery over a 65-week period. Resilience of Z. muelleri varied significantly with disturbance intensity; Z. muelleri recovered rapidly (within 2 weeks) from low-intensity disturbance (shoot loss), and rates of recovery appeared related to initial shoot length. Recovery via rhizome encroachment (asexual regeneration) from high-intensity disturbance (loss of entire plant) varied among locations, ranging from 18-35 weeks, whereas the ability to recover was apparently lost (at least within the time frame of this study) when recovery depended on sexual regeneration, suggesting that seeds do not provide a mechanism of recovery against intense small-scale disturbances. The lack of sexual recruits into disturbed sites is surprising as our initial surveys of genotypic diversity (using nine polymorphic microsatellite loci) at these location indicate that populations are maintained by a mix of sexual and asexual reproduction (genotypic diversity [R] varied from 0.24 to 0.44), and populations consisted of a mosaic of genotypes with on average 3.6 unique multilocus genotypes per 300 mm diameter plot. We therefore conclude that Z. muelleri populations within Lake Macquarie rely on clonal growth to recover from small-scale disturbances and that ongoing sexual recruitment by seeds into established seagrass beds (as opposed to bare areas arising from disturbance) must be the mechanism responsible for maintaining the observed mixed genetic composition of Z. muelleri seagrass meadows. PMID:24634729

Transmission rates of the bacterial endosymbiont, Neorickettsia risticii, during the asexual reproduction phase of its digenean host, Plagiorchis elegans, within naturally infected lymnaeid snails.

PubMed

Greiman, Stephen E; Tkach, Vasyl V; Vaughan, Jefferson A

2013-10-22

Neorickettsia are obligate intracellular bacterial endosymbionts of digenean parasites present in all lifestages of digeneans. Quantitative information on the transmission of neorickettsial endosymbionts throughout the complex life cycles of digeneans is lacking. This study quantified the transmission of Neorickettsia during the asexual reproductive phase of a digenean parasite, Plagiorchis elegans, developing within naturally parasitized lymnaeid pond snails. Lymnaea stagnalis snails were collected from 3 ponds in Nelson County, North Dakota and screened for the presence of digenean cercariae. Cercariae were identified to species by PCR and sequencing of the 28S rRNA gene. Neorickettsia infections were initially detected using nested PCR and sequencing of a partial 16S rRNA gene of pooled cercariae shed from each parasitized snail. Fifty to 100 single cercariae or sporocysts were isolated from each of six parasitized snails and tested for the presence of Neorickettsia using nested PCR to estimate the efficiency at which Neorickettsia were transmitted to cercariae during asexual development of the digenean. A total of 616 L. stagnalis were collected and 240 (39%) shed digenean cercariae. Of these, 18 (8%) were Neorickettsia-positive. Six Neorickettsia infections were selected to determine the transmission efficiency of Neorickettsia from mother to daughter sporocyst and from daughter sporocyst to cercaria. The prevalence of neorickettsiae in cercariae varied from 11 to 91%. The prevalence of neorickettsiae in sporocysts from one snail was 100%. Prevalence of Neorickettsia infection in cercariae of Plagiorchis elegans was variable and never reached 100%. Reasons for this are speculative, however, the low prevalence of Neorickettsia observed in some of our samples (11 to 52%) differs from the high prevalence of other, related bacterial endosymbionts, e.g. Wolbachia in Wolbachia-dependent filariid nematodes, where the prevalence among progeny is universally 100%. This suggests that, unlike the Wolbachia-filaria relationship, the Neorickettsia-digenean relationship is not obligatory mutualism. Our study represents the first quantitative estimate of the Neorickettsia transmission through the asexual phase of the digenean life cycle.

Emergent rules for codon choice elucidated by editing rare arginine codons in Escherichia coli

PubMed Central

Napolitano, Michael G.; Landon, Matthieu; Gregg, Christopher J.; Lajoie, Marc J.; Govindarajan, Lakshmi; Mosberg, Joshua A.; Kuznetsov, Gleb; Goodman, Daniel B.; Vargas-Rodriguez, Oscar; Isaacs, Farren J.; Söll, Dieter; Church, George M.

2016-01-01

The degeneracy of the genetic code allows nucleic acids to encode amino acid identity as well as noncoding information for gene regulation and genome maintenance. The rare arginine codons AGA and AGG (AGR) present a case study in codon choice, with AGRs encoding important transcriptional and translational properties distinct from the other synonymous alternatives (CGN). We created a strain of Escherichia coli with all 123 instances of AGR codons removed from all essential genes. We readily replaced 110 AGR codons with the synonymous CGU codons, but the remaining 13 “recalcitrant” AGRs required diversification to identify viable alternatives. Successful replacement codons tended to conserve local ribosomal binding site-like motifs and local mRNA secondary structure, sometimes at the expense of amino acid identity. Based on these observations, we empirically defined metrics for a multidimensional “safe replacement zone” (SRZ) within which alternative codons are more likely to be viable. To evaluate synonymous and nonsynonymous alternatives to essential AGRs further, we implemented a CRISPR/Cas9-based method to deplete a diversified population of a wild-type allele, allowing us to evaluate exhaustively the fitness impact of all 64 codon alternatives. Using this method, we confirmed the relevance of the SRZ by tracking codon fitness over time in 14 different genes, finding that codons that fall outside the SRZ are rapidly depleted from a growing population. Our unbiased and systematic strategy for identifying unpredicted design flaws in synthetic genomes and for elucidating rules governing codon choice will be crucial for designing genomes exhibiting radically altered genetic codes. PMID:27601680

Molecular evidence for the first records of facultative parthenogenesis in elapid snakes

PubMed Central

Sanders, K. L.

2018-01-01

Parthenogenesis is a form of asexual reproduction by which embryos develop from unfertilized eggs. Parthenogenesis occurs in reptiles; however, it is not yet known to occur in the widespread elapid snakes (Elapidae), which include well-known taxa such as cobras, mambas, taipans and sea snakes. Here, we describe the production of viable parthenogens in two species of Australo-Papuan elapids with divergent reproductive modes: the oviparous coastal/Papuan taipan (Oxyuranus scutellatus) and the viviparous southern death adder (Acanthophis antarcticus). Analyses of nuclear SNP data excluded paternity for putative fathers and convincingly demonstrated asexual reproduction, thus representing the first evidence of facultative parthenogenesis in Elapidae. Our finding has broad implications for understanding the evolution of reproductive diversity in snakes, as well as managing the conservation of genetic diversity in wild and captive populations. PMID:29515892

Molecular evidence for the first records of facultative parthenogenesis in elapid snakes.

PubMed

Allen, L; Sanders, K L; Thomson, V A

2018-02-01

Parthenogenesis is a form of asexual reproduction by which embryos develop from unfertilized eggs. Parthenogenesis occurs in reptiles; however, it is not yet known to occur in the widespread elapid snakes (Elapidae), which include well-known taxa such as cobras, mambas, taipans and sea snakes. Here, we describe the production of viable parthenogens in two species of Australo-Papuan elapids with divergent reproductive modes: the oviparous coastal/Papuan taipan ( Oxyuranus scutellatus ) and the viviparous southern death adder ( Acanthophis antarcticus ). Analyses of nuclear SNP data excluded paternity for putative fathers and convincingly demonstrated asexual reproduction, thus representing the first evidence of facultative parthenogenesis in Elapidae. Our finding has broad implications for understanding the evolution of reproductive diversity in snakes, as well as managing the conservation of genetic diversity in wild and captive populations.

Sponge budding is a spatiotemporal morphological patterning process: Insights from synchrotron radiation-based x-ray microtomography into the asexual reproduction of Tethya wilhelma.

PubMed

Hammel, Jörg U; Herzen, Julia; Beckmann, Felix; Nickel, Michael

2009-09-08

Primary agametic-asexual reproduction mechanisms such as budding and fission are present in all non-bilaterian and many bilaterian animal taxa and are likely to be metazoan ground pattern characters. Cnidarians display highly organized and regulated budding processes. In contrast, budding in poriferans was thought to be less specific and related to the general ability of this group to reorganize their tissues. Here we test the hypothesis of morphological pattern formation during sponge budding. We investigated the budding process in Tethya wilhelma (Demospongiae) by applying 3D morphometrics to high resolution synchrotron radiation-based x-ray microtomography (SR-muCT) image data. We followed the morphogenesis of characteristic body structures and identified distinct morphological states which indeed reveal characteristic spatiotemporal morphological patterns in sponge bud development. We discovered the distribution of skeletal elements, canal system and sponge tissue to be based on a sequential series of distinct morphological states. Based on morphometric data we defined four typical bud stages. Once they have reached the final stage buds are released as fully functional juvenile sponges which are morphologically and functionally equivalent to adult specimens. Our results demonstrate that budding in demosponges is considerably more highly organized and regulated than previously assumed. Morphological pattern formation in asexual reproduction with underlying genetic regulation seems to have evolved early in metazoans and was likely part of the developmental program of the last common ancestor of all Metazoa (LCAM).

Sponge budding is a spatiotemporal morphological patterning process: Insights from synchrotron radiation-based x-ray microtomography into the asexual reproduction of Tethya wilhelma

PubMed Central

Hammel, Jörg U; Herzen, Julia; Beckmann, Felix; Nickel, Michael

2009-01-01

Background Primary agametic-asexual reproduction mechanisms such as budding and fission are present in all non-bilaterian and many bilaterian animal taxa and are likely to be metazoan ground pattern characters. Cnidarians display highly organized and regulated budding processes. In contrast, budding in poriferans was thought to be less specific and related to the general ability of this group to reorganize their tissues. Here we test the hypothesis of morphological pattern formation during sponge budding. Results We investigated the budding process in Tethya wilhelma (Demospongiae) by applying 3D morphometrics to high resolution synchrotron radiation-based x-ray microtomography (SR-μCT) image data. We followed the morphogenesis of characteristic body structures and identified distinct morphological states which indeed reveal characteristic spatiotemporal morphological patterns in sponge bud development. We discovered the distribution of skeletal elements, canal system and sponge tissue to be based on a sequential series of distinct morphological states. Based on morphometric data we defined four typical bud stages. Once they have reached the final stage buds are released as fully functional juvenile sponges which are morphologically and functionally equivalent to adult specimens. Conclusion Our results demonstrate that budding in demosponges is considerably more highly organized and regulated than previously assumed. Morphological pattern formation in asexual reproduction with underlying genetic regulation seems to have evolved early in metazoans and was likely part of the developmental program of the last common ancestor of all Metazoa (LCAM). PMID:19737392

Conserved meiotic machinery in Glomus spp., a putatively ancient asexual fungal lineage.

PubMed

Halary, Sébastien; Malik, Shehre-Banoo; Lildhar, Levannia; Slamovits, Claudio H; Hijri, Mohamed; Corradi, Nicolas

2011-01-01

Arbuscular mycorrhizal fungi (AMF) represent an ecologically important and evolutionarily intriguing group of symbionts of land plants, currently thought to have propagated clonally for over 500 Myr. AMF produce multinucleate spores and may exchange nuclei through anastomosis, but meiosis has never been observed in this group. A provocative alternative for their successful and long asexual evolutionary history is that these organisms may have cryptic sex, allowing them to recombine alleles and compensate for deleterious mutations. This is partly supported by reports of recombination among some of their natural populations. We explored this hypothesis by searching for some of the primary tools for a sustainable sexual cycle--the genes whose products are required for proper completion of meiotic recombination in yeast--in the genomes of four AMF and compared them with homologs of representative ascomycete, basidiomycete, chytridiomycete, and zygomycete fungi. Our investigation used molecular and bioinformatic tools to identify homologs of 51 meiotic genes, including seven meiosis-specific genes and other "core meiotic genes" conserved in the genomes of the AMF Glomus diaphanum (MUCL 43196), Glomus irregulare (DAOM-197198), Glomus clarum (DAOM 234281), and Glomus cerebriforme (DAOM 227022). Homology of AMF meiosis-specific genes was verified by phylogenetic analyses with representative fungi, animals (Mus, Hydra), and a choanoflagellate (Monosiga). Together, these results indicate that these supposedly ancient asexual fungi may be capable of undergoing a conventional meiosis; a hypothesis that is consistent with previous reports of recombination within and across some of their populations.

Significant competitive advantage conferred by meiosis and syngamy in the yeast Saccharomyces cerevisiae.

PubMed Central

Birdsell, J; Wills, C

1996-01-01

The presumed advantages of genetic recombinations are difficult to demonstrate directly. To investigate the effects of recombination and background heterozygosity on competitive ability, we have performed serial-transfer competition experiments between isogenic sexual and asexual strains of the yeast Saccharomyces cerevisiae. The members of these diploid pairs of strains differed only in being heterozygous (sexual) or homozygous (asexual) at the mating type or MAT locus. Competing pairs had either a completely homozygous or a heterozygous genetic background, the latter being heterozygous at many different loci throughout the genome. A round of meiotic recombination (automixis) conferred a large and statistically significant enhancement of competitive ability on sexual strains with a heterozygous genetic background. By contrast, in homozygous background competitions, meiosis decreased the sexual strains' initial relative competitive ability. In all cases, however, the sexual strains outcompeted their isogenic asexual counterparts, whether meiotic recombination had occurred or not. In some genetic backgrounds, this was due in part to an overdominance effect on competitive advantage of heterozygosity at the MAT locus. The advantage of the sexual strains also increased significantly during the course of the homozygous background competitions, particularly when meiosis had occurred. This latter effect either did not occur or was very weak in heterozygous background competitions. Overall, sexual strains with heterozygous genetic backgrounds had a significantly higher initial relative competitive ability than those with homozygous backgrounds. The advantage of mating type heterozygosity in this organism extends far beyond the ability to recombine meiotically. PMID:8570658

Geographical parthenogenesis and population genetic structure in the alpine species Ranunculus kuepferi (Ranunculaceae).

PubMed

Cosendai, A-C; Wagner, J; Ladinig, U; Rosche, C; Hörandl, E

2013-06-01

Geographical parthenogenesis describes the enigmatic phenomenon that asexual organisms have larger distribution areas than their sexual relatives, especially in previously glaciated areas. Classical models suggest temporary advantages to asexuality in colonization scenarios because of uniparental reproduction and clonality. We analyzed population genetic structure and self-fertility of the plant species Ranunculus kuepferi on 59 populations from the whole distribution area (European Alps, Apennines and Corsica). Amplified fragment length polymorphisms (AFLPs) and five microsatellite loci revealed individual genotypes for all populations and mostly insignificant differences between diploid sexuals and tetraploid apomicts in all measures of genetic diversity. Low frequencies of private AFLP fragments/simple sequence repeat alleles, and character incompatibility analyses suggest that facultative recombination explains best the unexpectedly high genotypic diversity of apomicts. STRUCTURE analyses using AFLPs revealed a higher number of partitions and a stronger geographical subdivision for diploids than for tetraploids, which contradicts expectations of standard gene flow models, but indicates a reduction of genetic structure in asexuals. Apomictic populations exhibited high admixture near the sexual area, but appeared rather uniform in remote areas. Bagging experiments and analyses of pollen tube growth confirmed self-fertility for pollen-dependent apomicts, but self-sterility for diploid sexuals. Facultative apomixis combines advantages of both modes of reproduction: uniparental reproduction allows for rapid colonization of remote areas, whereas facultative sexuality and polyploidy maintains genetic diversity within apomictic populations. The density dependence of outcrossing limits range expansions of sexual populations.

Geographical parthenogenesis and population genetic structure in the alpine species Ranunculus kuepferi (Ranunculaceae)

PubMed Central

Cosendai, A-C; Wagner, J; Ladinig, U; Rosche, C; Hörandl, E

2013-01-01

Geographical parthenogenesis describes the enigmatic phenomenon that asexual organisms have larger distribution areas than their sexual relatives, especially in previously glaciated areas. Classical models suggest temporary advantages to asexuality in colonization scenarios because of uniparental reproduction and clonality. We analyzed population genetic structure and self-fertility of the plant species Ranunculus kuepferi on 59 populations from the whole distribution area (European Alps, Apennines and Corsica). Amplified fragment length polymorphisms (AFLPs) and five microsatellite loci revealed individual genotypes for all populations and mostly insignificant differences between diploid sexuals and tetraploid apomicts in all measures of genetic diversity. Low frequencies of private AFLP fragments/simple sequence repeat alleles, and character incompatibility analyses suggest that facultative recombination explains best the unexpectedly high genotypic diversity of apomicts. STRUCTURE analyses using AFLPs revealed a higher number of partitions and a stronger geographical subdivision for diploids than for tetraploids, which contradicts expectations of standard gene flow models, but indicates a reduction of genetic structure in asexuals. Apomictic populations exhibited high admixture near the sexual area, but appeared rather uniform in remote areas. Bagging experiments and analyses of pollen tube growth confirmed self-fertility for pollen-dependent apomicts, but self-sterility for diploid sexuals. Facultative apomixis combines advantages of both modes of reproduction: uniparental reproduction allows for rapid colonization of remote areas, whereas facultative sexuality and polyploidy maintains genetic diversity within apomictic populations. The density dependence of outcrossing limits range expansions of sexual populations. PMID:23403961

A combinational theory for maintenance of sex

PubMed Central

Hörandl, E

2010-01-01

Sexual reproduction implies high costs, but it is difficult to give evidence for evolutionary advantages that would explain the predominance of meiotic sex in eukaryotes. A combinational theory discussing evolution, maintenance and loss of sex may resolve the problem. The main function of sex is the restoration of DNA and consequently a higher quality of offspring. Recombination at meiosis evolved, perhaps, as a repair mechanism of DNA strand damages. This mechanism is most efficient for DNA restoration in multicellular eukaryotes, because the initial cell starts with a re-optimized genome, which is passed to all the daughter cells. Meiosis acts also as creator of variation in haploid stages, in which selection can purge most efficiently deleterious mutations. A prolonged diploid phase buffers the effects of deleterious recessive alleles as well as epigenetic defects and is thus optimal for prolonged growth periods. For complex multicellular organisms, the main advantage of sexuality is thus the alternation of diploid and haploid stages, combining advantages of both. A loss of sex is constrained by several, partly group-specific, developmental features. Hybridization may trigger shifts from sexual to asexual reproduction, but crossing barriers of the parental sexual species limit this process. For the concerted break-up of meiosis-outcrossing cycles plus silencing of secondary features, various group-specific changes in the regulatory system may be required. An establishment of asexuals requires special functional modifications and environmental opportunities. Costs for maintenance of meiotic sex are consequently lower than a shift to asexual reproduction. PMID:19623209

Hurricane-driven patterns of clonality in an ecosystem engineer: the Caribbean coral Montastraea annularis.

PubMed

Foster, Nicola L; Baums, Iliana B; Sanchez, Juan A; Paris, Claire B; Chollett, Iliana; Agudelo, Claudia L; Vermeij, Mark J A; Mumby, Peter J

2013-01-01

K-selected species with low rates of sexual recruitment may utilise storage effects where low adult mortality allows a number of individuals to persist through time until a favourable recruitment period occurs. Alternative methods of recruitment may become increasingly important for such species if the availability of favourable conditions for sexual recruitment decline under rising anthropogenic disturbance and climate change. Here, we test the hypotheses that asexual dispersal is an integral life history strategy not only in branching corals, as previously reported, but also in a columnar, 'K-selected' coral species, and that its prevalence is driven by the frequency of severe hurricane disturbance. Montastraea annularis is a long-lived major frame-work builder of Caribbean coral reefs but its survival is threatened by the consequences of climate induced disturbance, such as bleaching, ocean acidification and increased prevalence of disease. 700 M. annularis samples from 18 reefs within the Caribbean were genotyped using six polymorphic microsatellite loci. We demonstrate that asexual reproduction occurs at varying frequency across the species-range and significantly contributes to the local abundance of M. annularis, with its contribution increasing in areas with greater hurricane frequency. We tested several competing hypotheses that might explain the observed pattern of genotypic diversity. 64% of the variation in genotypic diversity among the sites was explained by hurricane incidence and reef slope, demonstrating that large-scale disturbances combine with local habitat characteristics to shape the balance between sexual and asexual reproduction in populations of M. annularis.

A putative APSES transcription factor is necessary for normal growth and development of Aspergillus nidulans.

PubMed

Lee, Ji-Yeon; Kim, Lee-Han; Kim, Ha-Eun; Park, Jae-Sin; Han, Kap-Hoon; Han, Dong-Min

2013-12-01

The nsdD gene encoding a GATA type transcription factor positively controls sexual development in Aspergillus nidulans. According to microarray data, 20 genes that were upregulated by deleting nsdD during various life cycle stages were randomly selected and deleted for functional analysis. None of the mutants showed apparent changes in growth or development compared with those of the wild-type except the AN3154 gene that encodes a putative APSES transcription factor and is an ortholog of Saccharomyces cerevisiae swi4. Deleting AN3154 resulted in retarded growth and development, and the gene was named rgdA (retared growth and development). The rgdA deletion mutant developed a reduced number of conidia even under favorable conditions for asexual development. The retarded growth and development was partially suppressed by the veA1 mutation. The conidial heads of the mutant aborted, showing reduced and irregular shaped phialides. Fruiting body development was delayed compared with that in the wild-type. The mutant did not respond to various nutritional or environmental factors that affected the development patterns. The rgdA gene was expressed at low levels throughout the life cycle and was not significantly affected by several regulators of sexual and asexual development such as nsdD, veA, stuA, or brlA. However, the rgdA gene affected brlA and abaA expression, which function as key regulators of asexual sporulation, suggesting that rgdA functions upstream of those genes.

FvSTR1, a striatin orthologue in Fusarium virguliforme, is required for asexual development and virulence.

PubMed

Islam, Kazi T; Bond, Jason P; Fakhoury, Ahmad M

2017-08-01

The soil-borne fungus Fusarium virguliforme causes sudden death syndrome (SDS), one of the most devastating diseases of soybean in North and South America. Despite the importance of SDS, a clear understanding of the fungal pathogenicity factors that affect the development of this disease is still lacking. We have identified FvSTR1, a F. virguliforme gene, which encodes a protein similar to a family of striatin proteins previously reported to regulate signalling pathways, cell differentiation, conidiation, sexual development, and virulence in filamentous fungi. Striatins are multi-domain proteins that serve as scaffolding units in the striatin-interacting phosphatase and kinase (STRIPAK) complex in fungi and animals. To address the function of a striatin homologue in F. virguliforme, FvSTR1 was disrupted and functionally characterized using a gene knock out strategy. The resulting Fvstr1 mutants were largely impaired in conidiation and pigmentation, and displayed defective conidia and conidiophore morphology compared to the wild-type and ectopic transformants. Greenhouse virulence assays revealed that the disruption of FvSTR1 resulted in complete loss of virulence in F. virguliforme. Microtome studies using fluorescence microscopy showed that the Fvstr1 mutants were defective in their ability to colonize the vascular system. The Fvstr1 mutants also showed a reduced transcript level of genes involved in asexual reproduction and in the production of secondary metabolites. These results suggest that FvSTR1 has a critical role in asexual development and virulence in F. virguliforme.

Conserved Meiotic Machinery in Glomus spp., a Putatively Ancient Asexual Fungal Lineage

PubMed Central

Halary, Sébastien; Malik, Shehre-Banoo; Lildhar, Levannia; Slamovits, Claudio H.; Hijri, Mohamed; Corradi, Nicolas

2011-01-01

Arbuscular mycorrhizal fungi (AMF) represent an ecologically important and evolutionarily intriguing group of symbionts of land plants, currently thought to have propagated clonally for over 500 Myr. AMF produce multinucleate spores and may exchange nuclei through anastomosis, but meiosis has never been observed in this group. A provocative alternative for their successful and long asexual evolutionary history is that these organisms may have cryptic sex, allowing them to recombine alleles and compensate for deleterious mutations. This is partly supported by reports of recombination among some of their natural populations. We explored this hypothesis by searching for some of the primary tools for a sustainable sexual cycle—the genes whose products are required for proper completion of meiotic recombination in yeast—in the genomes of four AMF and compared them with homologs of representative ascomycete, basidiomycete, chytridiomycete, and zygomycete fungi. Our investigation used molecular and bioinformatic tools to identify homologs of 51 meiotic genes, including seven meiosis-specific genes and other “core meiotic genes” conserved in the genomes of the AMF Glomus diaphanum (MUCL 43196), Glomus irregulare (DAOM-197198), Glomus clarum (DAOM 234281), and Glomus cerebriforme (DAOM 227022). Homology of AMF meiosis-specific genes was verified by phylogenetic analyses with representative fungi, animals (Mus, Hydra), and a choanoflagellate (Monosiga). Together, these results indicate that these supposedly ancient asexual fungi may be capable of undergoing a conventional meiosis; a hypothesis that is consistent with previous reports of recombination within and across some of their populations. PMID:21876220

Regulation of Conidiation by Light in Aspergillus nidulans

PubMed Central

Ruger-Herreros, Carmen; Rodríguez-Romero, Julio; Fernández-Barranco, Raul; Olmedo, María; Fischer, Reinhard; Corrochano, Luis M.; Canovas, David

2011-01-01

Light regulates several aspects of the biology of many organisms, including the balance between asexual and sexual development in some fungi. To understand how light regulates fungal development at the molecular level we have used Aspergillus nidulans as a model. We have performed a genome-wide expression analysis that has allowed us to identify >400 genes upregulated and >100 genes downregulated by light in developmentally competent mycelium. Among the upregulated genes were genes required for the regulation of asexual development, one of the major biological responses to light in A. nidulans, which is a pathway controlled by the master regulatory gene brlA. The expression of brlA, like conidiation, is induced by light. A detailed analysis of brlA light regulation revealed increased expression after short exposures with a maximum after 60 min of light followed by photoadaptation with longer light exposures. In addition to brlA, genes flbA–C and fluG are also light regulated, and flbA–C are required for the correct light-dependent regulation of the upstream regulator fluG. We have found that light induction of brlA required the photoreceptor complex composed of a phytochrome FphA, and the white-collar homologs LreA and LreB, and the fluffy genes flbA–C. We propose that the activation of regulatory genes by light is the key event in the activation of asexual development by light in A. nidulans. PMID:21624998

Hurricane-Driven Patterns of Clonality in an Ecosystem Engineer: The Caribbean Coral Montastraea annularis

PubMed Central

Foster, Nicola L.; Baums, Iliana B.; Sanchez, Juan A.; Paris, Claire B.; Chollett, Iliana; Agudelo, Claudia L.; Vermeij, Mark J. A.; Mumby, Peter J.

2013-01-01

K-selected species with low rates of sexual recruitment may utilise storage effects where low adult mortality allows a number of individuals to persist through time until a favourable recruitment period occurs. Alternative methods of recruitment may become increasingly important for such species if the availability of favourable conditions for sexual recruitment decline under rising anthropogenic disturbance and climate change. Here, we test the hypotheses that asexual dispersal is an integral life history strategy not only in branching corals, as previously reported, but also in a columnar, ‘K-selected’ coral species, and that its prevalence is driven by the frequency of severe hurricane disturbance. Montastraea annularis is a long-lived major frame-work builder of Caribbean coral reefs but its survival is threatened by the consequences of climate induced disturbance, such as bleaching, ocean acidification and increased prevalence of disease. 700 M. annularis samples from 18 reefs within the Caribbean were genotyped using six polymorphic microsatellite loci. We demonstrate that asexual reproduction occurs at varying frequency across the species-range and significantly contributes to the local abundance of M. annularis, with its contribution increasing in areas with greater hurricane frequency. We tested several competing hypotheses that might explain the observed pattern of genotypic diversity. 64% of the variation in genotypic diversity among the sites was explained by hurricane incidence and reef slope, demonstrating that large-scale disturbances combine with local habitat characteristics to shape the balance between sexual and asexual reproduction in populations of M. annularis. PMID:23308185

Achyranthis bidentatae radix enhanced articular distribution and anti-inflammatory effect of berberine in Sanmiao Wan using an acute gouty arthritis rat model.

PubMed

Wu, Juan; Li, Jingya; Li, Wei; Sun, Bei; Xie, Jin; Cheng, Wenming; Zhang, Qunlin

2018-07-15

Sanmiao Wan (SMW) has been a basic prescription employed for the treatment for gout in the clinic since Yuan dynasty. Achyranthis bidentatae radix (ABR) is designed as a lower-guiding drug in SMW to augment the articular accumulation of active ingredients and improve the anti-inflammatory effect. Present study was undertaken to investigate the dose-response relationship of berberine in SMW between the articular concentration and anti-inflammatory effect in the knee joint under the lower-guiding of ABR. Rats were divided into control group, model group and SMW without or with low, medium and high doses of ABR groups. Rat model of acute gouty arthritis (AGA) was established by intra-articular injection of 0.2 mL monosodium urate crystal (20 mg/mL) inside knee joint cavity on day 2 during drug treatment slots. Knee joint swelling, synovial hyperplasia and inflammatory cell infiltration were investigated for anti-inflammatory study. The concentrations of berberine in rat plasma and tissues were determined by UPLC-MS/MS method. The effect of ABR on the expression levels of P-glycoprotein (P-gp) and MDR1 mRNA in the synovial tissues of knee joints in AGA rats was examined by Western blot and RT-qPCR assay, respectively. The distribution of berberine increased by 6.53%, 44.31% and 212.96% in the knee joint and 474.93%, 631.01% and 1063.3% in the ankle for SMW with low, medium and high doses of ABR groups, compared with SMW without ABR group. Similarly, the plasma level of berberine increased by 19.81%, 143.4% and 681.13%. On the contrary, the distribution of berberine evidently decreased 3.23, 10.61 and 46.21-fold in heart and 3.68, 6.74 and 24.78-fold in lung. SMW with different doses of ABR groups exhibited better efficiency than SMW without ABR group on ameliorating knee joint swelling, inhibiting synovial hyperplasia and alleviating inflammatory cell infiltration of AGA rats. The treatment with ABR could down-regulate the MDR1 mRNA and P-gp expressions of synovial tissues of knee joints in AGA rats. The enhanced articular distribution of berberine in SMW was attributed to the lower-guiding effect of ABR, which could evidently increase the plasma concentration of berberine, improve the supply of blood of inflamed joint, reduce the distribution of berberine in heart and lung and significantly inhibit the MDR1 mRNA and P-gp expression of synovial tissues of knee joints in AGA rats. The dose-response relationship of berberine between the enhanced articular concentration and improved anti-inflammatory effect in the knee joint under the lower-guiding of ABR was observed for the first time. Copyright © 2018 Elsevier B.V. All rights reserved.

A restoration genetics guide for coral reef conservation.

PubMed

Baums, Iliana B

2008-06-01

Worldwide degradation of coral reef communities has prompted a surge in restoration efforts. They proceed largely without considering genetic factors because traditionally, coral populations have been regarded as open over large areas with little potential for local adaptation. Since, biophysical and molecular studies indicated that most populations are closed over shorter time and smaller spatial scales. Thus, it is justified to re-examine the potential for site adaptation in corals. There is ample evidence for differentiated populations, inbreeding, asexual reproduction and the occurrence of ecotypes, factors that may facilitate local adaptation. Discovery of widespread local adaptation would influence coral restoration projects mainly with regard to the physical and evolutionary distance from the source wild and/or captive bred propagules may be moved without causing a loss of fitness in the restored population. Proposed causes for loss of fitness as a result of (plant) restoration efforts include founder effects, genetic swamping, inbreeding and/or outbreeding depression. Direct evidence for any of these processes is scarce in reef corals due to a lack of model species that allow for testing over multiple generations and the separation of the relative contributions of algal symbionts and their coral hosts to the overall performance of the coral colony. This gap in our knowledge may be closed by employing novel population genetic and genomics approaches. The use of molecular tools may aid managers in the selection of appropriate propagule sources, guide spatial arrangement of transplants, and help in assessing the success of coral restoration projects by tracking the performance of transplants, thereby generating important data for future coral reef conservation and restoration projects.

New structures of Fe3S for rare-earth-free permanent magnets

NASA Astrophysics Data System (ADS)

Yu, Shu; Zhao, Xin; Wu, Shunqing; Nguyen, Manh Cuong; Zhu, Zi-zhong; Wang, Cai-Zhuang; Ho, Kai-Ming

2018-02-01

We applied an adaptive genetic algorithm (AGA) to search for low-energy crystal structures of Fe3S. A number of structures with energies lower than that of the experimentally reported Pnma and I-4 structures have been obtained from our AGA searches. These low-energy structures can be classified as layer-motif and column-motif structures. In the column-motif structures, Fe atoms self-assemble into rods with a bcc type of underlying lattice, which are separated by the holes terminated by S atoms. In the layer-motif structures, the bulk Fe is broken into slabs of several layers passivated by S atoms. Magnetic property calculations showed that the column-motif structures exhibit reasonably high uniaxial magnetic anisotropy. In addition, we examined the effect of Co doping to Fe3S and found that magnetic anisotropy can be enhanced through Co doping.

New structures of Fe3S for rare-earth-free permanent magnets

DOE PAGES

Yu, Shu; Zhao, Xin; Wu, Shunqing; ...

2018-02-25

We applied adaptive genetic algorithm (AGA) to search for low-energy crystal structures of Fe 3S. A number of structures with energies lower than that of the experimentally reported Pnma and I-4 structures have been obtained from our AGA searches. These low-energy structures can be classified as layer-motif and column-motif structures. In the column-motif structures, Fe atoms self-assemble into rods with bcc type of underlying lattice, which are separated by the holes terminated by S atoms. In the layer-motif structures, the bulk Fe is broken into slabs of several layers passivated by S atoms. Magnetic properties calculations showed that the column-motifmore » structures exhibit reasonably high uniaxial magnetic anisotropy. In addition, we examined the effect of Co doping to Fe 3S and found magnetic anisotropy can be enhanced through Co doping.« less

[Clinical classification and genetic mutation study of two pedigrees with type II Waardenburg syndrome].

PubMed

Chen, Yong; Yang, Fuwei; Zheng, Hexin; Zhu, Ganghua; Hu, Peng; Wu, Weijing

2015-12-01

To explore the molecular etiology of two pedigrees affected with type II Waardenburg syndrome (WS2) and to provide genetic diagnosis and counseling. Blood samples were collected from the proband and his family members. Following extraction of genomic DNA, the coding sequences of PAX3, MITF, SOX10 and SNAI2 genes were amplified with PCR and subjected to DNA sequencing to detect potential mutations. A heterozygous deletional mutation c.649_651delAGA in exon 7 of the MITF gene has been identified in all patients from the first family, while no mutation was found in the other WS2 related genes including PAX3, MITF, SOX10 and SNAI2. The heterozygous deletion mutation c.649_651delAGA in exon 7 of the MITF gene probably underlies the disease in the first family. It is expected that other genes may also underlie WS2.

Germline regeneration: the worms' turn.

PubMed

Weisblat, David A

2006-06-20

Asexual reproduction in the annelid Enchytraeus japonensis entails the regeneration of primordial germ cells from body parts that lack gonads. New primordial germ cells arise from piwi-expressing germline stem cells that are distinct from somatic stem cells.

Reduced telomere length is not associated with early signs of vascular aging in young men born after intrauterine growth restriction: a paradox?

PubMed

Laganović, Mario; Bendix, Laila; Rubelj, Ivica; Kirhmajer, Majda Vrkić; Slade, Neda; Lela, Ivana Vuković; Premužić, Vedran; Nilsson, Peter M; Jelaković, Bojan

2014-08-01

The mechanisms that increase cardiovascular risk in individuals born small for gestational age (SGA) are not well understood. Telomere shortening has been suggested to be a predictor of disease onset. Our aim was to determine whether impaired intrauterine growth is associated with early signs of vascular aging and whether telomere length could be a biomarker of this pathway. One hundred and fourteen healthy young men born SGA or after normal pregnancy [appropriate for gestational age (AGA)] were enrolled. Patient data were gathered from questionnaires and clinical exams, including blood pressure (BP) measurement routine laboratory analyses, and carotid intima-media thickness (cIMT). Leukocyte telomere length (LTL) was assessed by quantitative PCR. Birth data were obtained from medical records. The SGA group had significantly higher pulse pressure and cIMT, and a trend to increased SBP and heart rate in comparison to the AGA group. Interestingly, SGA men exhibited a 42% longer LTL than the AGA group. LTL was inversely associated with age, BMI, BP and birth parameters. In multiple regression analysis, BMI was the key determinant of SBP and cIMT. Young men born SGA show early signs of vascular aging. Unexpectedly, in our cohort, the SGA group had longer telomeres than the normal controls. Although longer telomeres are predictive of better health in the future, our findings could indicate a faster telomere attrition rate and probable early onset of cardiovascular risk in SGA participants. Follow-up of this cohort will clarify hypothesis and validate telomere dynamics as indicators of future health risks.

Improvement of androgenetic alopecia with topical Sophora flavescens Aiton extract, and identification of the two active compounds in the extract that stimulate proliferation of human hair keratinocytes.

PubMed

Takahashi, T; Ishino, A; Arai, T; Hamada, C; Nakazawa, Y; Iwabuchi, T; Tajima, M

2016-04-01

Androgenetic alopecia (AGA) is a hair loss disorder that commonly affects middle-aged men. To date, the properties of a number of natural or synthetic substances have been investigated for their ability to improve the condition. To evaluate the hair growth-promoting activities of an extract from the root of Sophora flavescens Aiton. We used a human hair keratinocyte proliferation assay and ex vivo organ cultures of human hair follicle to examine the potential of the extract to stimulate hair growth via anagen elongation. We isolated the compounds promoting the growth of epithelial cells, and determined their chemical structures. A randomized, double-blinded, placebo-controlled clinical study for S. flavescens extract was carried out for 6 months with patients with AGA. The extract stimulated the proliferation of hair keratinocytes at a concentration of 0.1 ng/mL, while 100 ng/mL of the extract had a marked effect on hair shaft elongation in an organ culture of human hair follicle. Cell proliferation assay-directed fractionation led to the identification of two pterocarpan derivatives, L-maackiain and medicarpin, as active compounds that promote the proliferation of human hair keratinocytes. Studies in human subjects showed that improvement in the inspected alopecia scores in the lotion plus extract group were significant over a period of 6 months (P < 0.01). S. flavescens root extract is effective for the treatment of AGA. The isolated two pterocarpans might have important role in this effect. © 2015 British Association of Dermatologists.

Extremely preterm infants small for gestational age are at risk for motor impairment at 3 years corrected age.

PubMed

Kato, Takeshi; Mandai, Tsurue; Iwatani, Sota; Koda, Tsubasa; Nagasaka, Miwako; Fujita, Kaori; Kurokawa, Daisuke; Yamana, Keiji; Nishida, Kosuke; Taniguchi-Ikeda, Mariko; Tanimura, Kenji; Deguchi, Masashi; Yamada, Hideto; Iijima, Kazumoto; Morioka, Ichiro

2016-02-01

Few studies have targeted psychomotor development and associated perinatal risk factors in Japanese very low birth weight (VLBW) infants who are severely small for gestational age (SGA). A single-center study was conducted in 104 Japanese VLBW infants who were born preterm, due to maternal, umbilical cord, or placental abnormalities, between 2000 and 2007. Psychomotor development as a developmental quotient (DQ) was assessed using the Kyoto Scale of Psychological Development at 3 years corrected age. Severely SGA was defined as birth weight or length below -2 standard deviation values of the mean values at the same gestation. VLBW infants were divided into 2 subgroups based on gestational age at birth: ⩾28 weeks (n=64) and <28 weeks (n=40). DQs of infants with severe SGA were compared with those of infants who were appropriate for gestational age (AGA). Factors associated with developmental disabilities in VLBW infants with severe SGA (n=23) were determined. In the group born at ⩾28 weeks gestation, infants with severe SGA had normal DQ values and did not significantly differ from those with AGA. However, in the group born at <28 weeks gestation, severe SGA infants had significantly lower postural-motor DQ values than AGA infants. Gestational age <28 weeks was an independent factor for low postural-motor DQ, regardless of the cause of severe SGA or pregnancy termination. Extremely preterm newborns with severe SGA are at risk of motor developmental disability at age 3 years. Copyright © 2015 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Photo- and thermally induced property change in Ag diffusion into Ag/As2Se3 thin films

NASA Astrophysics Data System (ADS)

Aparimita, Adyasha; Sripan, C.; Ganesan, R.; Naik, Ramakanta

2018-03-01

In the present report, we have prepared As2Se3 and bilayer Ag/As2Se3 chalcogenide thin films prepared by thermal evaporation process. The top Ag layer is being diffused into the bottom As2Se3 layer by 532 nm laser irradiation and thermal annealing process. The photo and thermal energy drives the Ag+ ions into the As2Se3 matrix that enhances the formation of As-Se-Ag solid solution which shows the changes of optical properties such as transmission, absorption power, refractive index, and optical band gap. The transmission power drastically decreased for the thermal-induced film than the laser induced one; and the reverse effect is seen for the absorption coefficient. The non-linear refractive index is found to be increased due to the Ag diffusion into As2Se3 film. The indirect allowed optical band gap is being reduced by a significant amount of 0.17 eV (thermal diffusion) and 0.03 eV (photo diffusion) from the Ag/As2Se3 film. The Ag diffusion creates chemical disorderness in the film observed from the two parameters which measures the degree of disorder such as Urbach energy and Tauc parameter. The structural change is not noticed in the studied film as seen from the X-ray diffraction pattern. Scanning electron microscopy and atomic force microscopy investigations showed that the surface morphology was influenced by the diffusion phenomena. The change in optical constants in such type of film can be used in optical waveguides and optical devices.

The Clinical Response to Gluten Challenge: A Review of the Literature

PubMed Central

Bruins, Maaike J.

2013-01-01

The aim of this review was to identify, evaluate and summarize all relevant studies reporting on the clinical response to gluten challenge by adult or pediatric patients with suspected or diagnosed coeliac disease (CD) on a gluten-free diet. We evaluated the effect of gluten challenge on changes in symptoms, intestinal mucosa histology, and serum antibodies. A systematic electronic search was performed for studies published as of 1966 using PubMed and Scopus databases. In the reviewed studies, doses ranged from 0.2 to 30 g/day of wheat gluten or comprised a gluten-containing diet. The onset of symptoms upon gluten intake varied largely from days to months and did not parallel serum antibody or histological changes. Within 3 months of gluten challenge, 70%–100% of pediatric CD patients became positive for AGA-IgA and EMA-IgA antibodies and 50%–70% for AGA-IgG. A limited number of trials suggest that no more than half of adult patients developed positive AGA-IgA, EMA-IgA, tTG-IgA or DGP-IgA/IgG titers. Approximately 50%–100% of pediatric and adult patients experienced mucosal relapse of gluten provocation within 3 months, which was preceded by increased mucosal intra-epithelial lymphocytes within several days of challenge. A 3-month high-dose gluten challenge should be suitable to diagnose the majority of CD patients. In some cases prolonged challenge may be needed to verify diagnosis. Combination testing for antibodies and mucosal histology may fasten the diagnosis. PMID:24284613

Effects of maternal folic acid supplementation on gene methylation and being small for gestational age.

PubMed

Qian, Y-Y; Huang, X-L; Liang, H; Zhang, Z-F; Xu, J-H; Chen, J-P; Yuan, W; He, L; Wang, L; Miao, M-H; Du, J; Li, D-K

2016-10-01

Being small for gestational age (SGA), a foetal growth abnormality, has a long-lasting impact on childhood health. Its aetiology and underlying mechanisms are not well understood. Underlying epigenetic changes of imprinted genes have emerged as a potential pathological pathway because they may be associated with growth, including SGA. As a common methyl donor, folic acid (FA) is essential for DNA methylation, synthesis and repair, and FA supplementation is widely recommended for women planning pregnancy. The present study aimed to investigate the inter-relationships among methylation levels of two imprinted genes [H19 differentially methylated regions (DMRs) and MEST DMRs], maternal FA supplementation and SGA. We conducted a case-control study. Umbilical cord blood was taken from 39 SGA infants and 49 controls whose birth weights are appropriate for gestational age (AGA). DNA methylation levels of H19 and MEST DMRs were determined by an analysis of mass array quantitative methylation. Statistically significantly higher methylation levels were observed at sites 7.8, 9 and 17.18 of H19 (P = 0.030, 0.016 and 0.050, respectively) in the SGA infants compared to the AGA group. In addition, the association was stronger in male births where the mothers took FA around conception at six H19 sites (P = 0.004, 0.005, 0.048, 0.002, 0.021 and 0.005, respectively). Methylation levels at H19 DMRs were higher in SGA infants compared to AGA controls. It appears that the association may be influenced by maternal peri-conception FA supplementation and also be sex-specific. © 2016 The British Dietetic Association Ltd.

Haemostatic profile of healthy premature small for gestational age neonates.

PubMed

Mitsiakos, George; Giougi, Evaggelia; Chatziioannidis, Ilias; Karagianni, Paraskevi; Papadakis, Emmanouil; Tsakalidis, Christos; Papaioannou, Georgia; Malindretos, Pavlos; Nikolaidis, Nikolaos

2010-08-01

The pathogenetic profile of premature Small for Gestational Age (SGA) neonates is strongly related to their haemostatic equilibrium, which is inadequately understood. To evaluate coagulation and fibrinolysis in premature SGA neonates before intervening with Vitamin K administration. We performed a comparison of coagulation, natural inhibitors and fibrinolysis between SGA and Appropriate for Gestational Age (AGA) infants born prematurely [gestational age (G.A.) <37 weeks]. Study population consisted of 139 preterm newborns, 68 of whom were SGA (25 males and 43 females), while 71 were AGA (37 males and 34 females) that consisted the control group. Blood samples were obtained within 30 minutes following birth and before the administration of vitamin K. Investigation included: PT, INR, APTT, fibrinogen, coagulation factors II, V, VII, VIII, IX, X, XI, XII, von Willebrand factor, protein C and free protein S, antithrombin (AT), APCR, tPA and PAI-1. The independent t-test and the Mann-Whitney U test were used to compare the differences between the values of haemostatic parameters. Premature SGA infants presented significantly lower levels of fibrinogen (p<0.029) and higher levels of VIIIc factor, APCR, tPA and PAI-1 (p<0.041, 0.017, 0.021 and 0.019 respectively). The two groups had similar demographic characteristics (except from birth weight), without significant differences in the values of other haemostatic parameters. Despite the statistically significant differentiation in the levels of fibrinogen, VIIIc factor, APCR, tPA and PAI-1, the rest of haemostatic parameters have similar values between SGA and AGA preterms. (c) 2010 Elsevier Ltd. All rights reserved.

Does gender affect career satisfaction and advancement in gastroenterology? Results of an AGA institute-sponsored survey.

PubMed

Gerson, Lauren B; Twomey, Kay; Hecht, Gail; Lee, Linda; McQuaid, Ken; Pizarro, Theresa T; Street, Sarah; Yoshida, Cynthia; Early, Dayna

2007-04-01

Women comprise 19% of the American Gastroenterological Association (AGA) membership. We performed a prospective study to determine whether female gastroenterologists were less likely to achieve career advancement and satisfaction. We administered an online survey to AGA members from 2004-2006. The survey contained questions regarding effects of gender on career advancement, satisfaction with career, promotional policies, and integration of family and career. A total of 457 individuals (response rate 9% after 2 major invitations) completed the survey, including 262 (57%) women (20% in private practice, 53% in academic careers, and 27% trainees) and 195 men (23% in private practice, 58% in academic careers, and 19% trainees). The male gastroenterologists were significantly older (P < .005) and in their careers for significantly more years (P = .002). There were no significant differences with respect to marital status, number of children, or number of hours worked between the genders. Men were more likely to achieve the rank of full professor (P = .035), and significantly more women reported that gender affected their career advancement (47% vs 9%; P < .001). Women in academic careers reported less satisfaction with their careers (P = .01) and perceived more difficulty in achieving promotion and tenure. Women were more likely to choose private practice careers because of part-time options (P = .025). Equal numbers of men and women in practice reported difficulty balancing work and family life. Significantly more female than male gastroenterologists perceive that gender has affected their career advancement. Female academic gastroenterologists reported less overall career satisfaction and promotion than male academic gastroenterologists.

49 CFR 193.2013 - Incorporation by reference.

Code of Federal Regulations, 2010 CFR

2010-10-01

... MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY LIQUEFIED NATURAL... incorporated materials are available for inspection in the Pipeline and Hazardous Materials Safety... referenced material 49 CFR Reference A. American Gas Association (AGA): (1) “Purging Principles and Practices...

VeA of Aspergillus niger increases spore dispersing capacity by impacting conidiophore architecture.

PubMed

Wang, Fengfeng; Dijksterhuis, Jan; Wyatt, Timon; Wösten, Han A B; Bleichrodt, Robert-Jan

2015-01-01

Aspergillus species are highly abundant fungi worldwide. Their conidia are among the most dominant fungal spores in the air. Conidia are formed in chains on the vesicle of the asexual reproductive structure called the conidiophore. Here, it is shown that the velvet protein VeA of Aspergillus niger maximizes the diameter of the vesicle and the spore chain length. The length and width of the conidiophore stalk and vesicle were reduced nearly twofold in a ΔveA strain. The latter implies a fourfold reduced surface area to develop chains of spores. Over and above this, the conidial chain length was approximately fivefold reduced. The calculated 20-fold reduction in formation of conidia by ΔveA fits the 8- to 17-fold decrease in counted spore numbers. Notably, morphology of the ΔveA conidiophores of A. niger was very similar to that of wild-type Aspergillus sydowii. This suggests that VeA is key in conidiophore architecture diversity in the fungal kingdom. The finding that biomass formation of the A. niger ΔveA strain was reduced twofold shows that VeA not only impacts dispersion capacity but also colonization capacity of A. niger.

Coalescence and genetic diversity in sexual populations under selection.

PubMed

Neher, Richard A; Kessinger, Taylor A; Shraiman, Boris I

2013-09-24

In sexual populations, selection operates neither on the whole genome, which is repeatedly taken apart and reassembled by recombination, nor on individual alleles that are tightly linked to the chromosomal neighborhood. The resulting interference between linked alleles reduces the efficiency of selection and distorts patterns of genetic diversity. Inference of evolutionary history from diversity shaped by linked selection requires an understanding of these patterns. Here, we present a simple but powerful scaling analysis identifying the unit of selection as the genomic "linkage block" with a characteristic length, , determined in a self-consistent manner by the condition that the rate of recombination within the block is comparable to the fitness differences between different alleles of the block. We find that an asexual model with the strength of selection tuned to that of the linkage block provides an excellent description of genetic diversity and the site frequency spectra compared with computer simulations. This linkage block approximation is accurate for the entire spectrum of strength of selection and is particularly powerful in scenarios with many weakly selected loci. The latter limit allows us to characterize coalescence, genetic diversity, and the speed of adaptation in the infinitesimal model of quantitative genetics.

Deleterious Wolbachia in the ant Formica truncorum.

PubMed

Wenseleers, T; Sundström, L; Billen, J

2002-03-22

Wolbachia is a maternally inherited bacterium that may manipulate the reproduction of its arthropod hosts. In insects, it is known to lead to inviable matings, cause asexual reproduction or kill male offspring, all to its own benefit, but to the detriment of its host. In social Hymenoptera, Wolbachia occurs widely, but little is known about its fitness effects. We report on a Wolbachia infection in the wood ant Formica truncorum, and evaluate whether it influences reproductive patterns. All 33 colonies of the study population were infected, suggesting that Wolbachia infection is at, or close to, fixation. Interestingly, in colonies with fewer infected workers, significantly more sexuals are produced, indicating that Wolbachia has deleterious effects in this species. In addition, adult workers are shown to have significantly lower infection rates (45%) than worker pupae (87%) or virgin queens (94%), suggesting that workers lose their infection over life. Clearance of Wolbachia infection has, to our knowledge, never been shown in any other natural system, but we argue that it may, in this case, represent an adaptive strategy to reduce colony load. The cause of fixation requires further study, but our data strongly suggest that Wolbachia has no influence on the sex ratio in this species.

Correlated responses to clonal selection in populations of Daphnia pulicaria: mechanisms of genetic correlation and the creative power of sex.

PubMed

Dudycha, Jeffry L; Snoke-Smith, Margaret; Alía, Ricardo

2013-02-01

Genetic correlations among traits alter evolutionary trajectories due to indirect selection. Pleiotropy, chance linkage, and selection can all lead to genetic correlations, but have different consequences for phenotypic evolution. We sought to assess the mechanisms contributing to correlations with size at maturity in the cyclic parthenogen Daphnia pulicaria. We selected on size in each of four populations that differ in the frequency of sex, and evaluated correlated responses in a life table. Size at advanced adulthood, reproductive output, and adult growth rate clearly showed greater responses in high-sex populations, with a similar pattern in neonate size and r. This pattern is expected only when trait correlations are favored by selection and the frequency of sex favors the creation and demographic expansion of highly fit clones. Juvenile growth and age at maturity did not diverge consistently. The inter-clutch interval appeared to respond more strongly in low-sex populations, but this was not statistically significant. Our data support the hypothesis that correlated selection is the strongest driver of genetic correlations, and suggest that in organisms with both sexual and asexual reproduction, adaptation can be enhanced by recombination.

Genealogies of rapidly adapting populations

PubMed Central

Neher, Richard A.; Hallatschek, Oskar

2013-01-01

The genetic diversity of a species is shaped by its recent evolutionary history and can be used to infer demographic events or selective sweeps. Most inference methods are based on the null hypothesis that natural selection is a weak or infrequent evolutionary force. However, many species, particularly pathogens, are under continuous pressure to adapt in response to changing environments. A statistical framework for inference from diversity data of such populations is currently lacking. Towards this goal, we explore the properties of genealogies in a model of continual adaptation in asexual populations. We show that lineages trace back to a small pool of highly fit ancestors, in which almost simultaneous coalescence of more than two lineages frequently occurs. Whereas such multiple mergers are unlikely under the neutral coalescent, they create a unique genetic footprint in adapting populations. The site frequency spectrum of derived neutral alleles, for example, is nonmonotonic and has a peak at high frequencies, whereas Tajima’s D becomes more and more negative with increasing sample size. Because multiple merger coalescents emerge in many models of rapid adaptation, we argue that they should be considered as a null model for adapting populations. PMID:23269838

New Conceptions: Biosocial Innovations and the Family.

ERIC Educational Resources Information Center

Edwards, John N.

1991-01-01

Discusses asexual reproductive technologies (in vitro fertilization, cryopreservation, artificial insemination, sperm banks, genetic engineering, ovum transfer, cloning, ectogenesis, surrogacy) and suggests that theoretical implications of technologies may bring dramatic social changes in the family. Outlines symbolically representational…

Genetic and environmental effects on morphology and asexual reproduction in the moss, Bryum bicolor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, A.J.

A distinctive form of Bryum bicolor, characterized by stoutly excurrent costae and abundant asexual gemmae, occurs on heavy metal-contaminated tailings of the Conrad Hill Mine in the Piedmont of North Carolina. Plants from two mine site populations, plus two other populations from Richmond, Virginia, were grown on three types of soil in order to determine the degree to which morphological traits, including the number of gemmae per plant, can be modified by substrate. All populations grew equally well in the mine soil, and there was no evidence that plants from the mine site populations were physiologically adapted for growth onmore » the contaminated tailings. Leaf dimensions, costa length, and number of gemmae per stem were strongly influenced by substrate, although some differences between populations were maintained under experimental conditions. Populations also differed in the efficacy with which plants regenerated from gametophytic fragments.« less

The More the Merrier?. Entropy and Statistics of Asexual Reproduction in Freshwater Planarians

NASA Astrophysics Data System (ADS)

Quinodoz, Sofia; Thomas, Michael A.; Dunkel, Jörn; Schötz, Eva-Maria

2011-04-01

The trade-off between traits in life-history strategies has been widely studied for sexual and parthenogenetic organisms, but relatively little is known about the reproduction strategies of asexual animals. Here, we investigate clonal reproduction in the freshwater planarian Schmidtea mediterranea, an important model organism for regeneration and stem cell research. We find that these flatworms adopt a randomized reproduction strategy that comprises both asymmetric binary fission and fragmentation (generation of multiple offspring during a reproduction cycle). Fragmentation in planarians has primarily been regarded as an abnormal behavior in the past; using a large-scale experimental approach, we now show that about one third of the reproduction events in S. mediterranea are fragmentations, implying that fragmentation is part of their normal reproductive behavior. Our analysis further suggests that certain characteristic aspects of the reproduction statistics can be explained in terms of a maximum relative entropy principle.

Purification and partial characterization of PfHRP-II protein of Plasmodium falciparum.

PubMed

Ghimire, Prakash; Samantaray, J C; Mirdha, B R; Patra, A K; Panda, A K

2003-12-01

The human malarial parasite Plasmodium falciparum secretes various intra-and extra-cellular proteins during its asexual life cycle in human RBC. Histidine rich protein-II (HRP-II) is one of the most prominent proteins, found to be secreted by P. falciparum throughout the asexual cycle with the peak during mature schizont stage of the parasite development in human IRBC. The high histidine content (35% of the total amino acids in protein) of this protein suggested the potential to bind divalent metal ions. We have demonstrated by metal chelate chromatography, an extraordinary capacity of HRP-II to bind nickel ions (Ni++) and employed this characteristic to purify the extra-cellular HRP-II protein secreted by P. falciparum from culture supernatant. The identity of the purified protein was verified by the relative molecular weight on SDS-PAGE, by reacting with polyclonal antibodies directed against it using Western blot technique.

Sexuality: from stigma, stereotypes and secrecy to coming out, communication and choice.

PubMed

Nay, Rhonda; McAuliffe, Linda; Bauer, Michael

2007-03-01

Ageism and sexism have been remarkably successful in portraying sexuality as the preserve of young people and stereotyping older people as asexual. Older people have colluded in the stereotype by passing as asexual and generally keeping secret their ongoing interest in, or expression of, sexuality. The labelling as 'deviant' and associated stigma experienced by people who dare to breach societal stereotypes are recognized as tools used by powerful vested interests to maintain and manage the norms and values of society. Despite the sanctions, people do find ways of resisting, and over time norms and values change. This paper notes the centrality of sexuality to identity and argues that nursing is pivotally placed to recognize and value the older person's sexuality and support older people to 'come out' and re-claim the sexuality of their choice. It provides a provocative vision of how care and attitudes might look in 2025.

Genomic analyses of primitive, wild and cultivated citrus provide insights into asexual reproduction.

PubMed

Wang, Xia; Xu, Yuantao; Zhang, Siqi; Cao, Li; Huang, Yue; Cheng, Junfeng; Wu, Guizhi; Tian, Shilin; Chen, Chunli; Liu, Yan; Yu, Huiwen; Yang, Xiaoming; Lan, Hong; Wang, Nan; Wang, Lun; Xu, Jidi; Jiang, Xiaolin; Xie, Zongzhou; Tan, Meilian; Larkin, Robert M; Chen, Ling-Ling; Ma, Bin-Guang; Ruan, Yijun; Deng, Xiuxin; Xu, Qiang

2017-05-01

The emergence of apomixis-the transition from sexual to asexual reproduction-is a prominent feature of modern citrus. Here we de novo sequenced and comprehensively studied the genomes of four representative citrus species. Additionally, we sequenced 100 accessions of primitive, wild and cultivated citrus. Comparative population analysis suggested that genomic regions harboring energy- and reproduction-associated genes are probably under selection in cultivated citrus. We also narrowed the genetic locus responsible for citrus polyembryony, a form of apomixis, to an 80-kb region containing 11 candidate genes. One of these, CitRWP, is expressed at higher levels in ovules of polyembryonic cultivars. We found a miniature inverted-repeat transposable element insertion in the promoter region of CitRWP that cosegregated with polyembryony. This study provides new insights into citrus apomixis and constitutes a promising resource for the mining of agriculturally important genes.

Cytogenetic evidence for asexual evolution of bdelloid rotifers.

PubMed

Mark Welch, Jessica L; Mark Welch, David B; Meselson, Matthew

2004-02-10

DNA sequencing has shown individual bdelloid rotifer genomes to contain two or more diverged copies of every gene examined and has revealed no closely similar copies. These and other findings are consistent with long-term asexual evolution of bdelloids. It is not entirely ruled out, however, that bdelloid genomes consist of previously undetected pairs of sequences so similar as to be identical over the regions sequenced, as might result if bdelloids were highly inbred sexual diploids or polyploids. Here, we employ fluorescent in situ hybridization with cosmid probes to determine the copy number and chromosomal distribution of the heat shock gene hsp82 and adjacent sequences in the bdelloid Philodina roseola. We conclude that the four copies identified by sequencing are the only ones present and that each is on a separate chromosome. Bdelloids therefore are not highly homozygous sexually reproducing diploids or polyploids.

Characterization of 21 microsatellite markers from cogongrass, Imperata cylindrica (Poaceae), a weed species distributed worldwide.

PubMed

Chiang, Yu-Chung; Tsai, Chi-Chu; Hsu, Tsai-Wen; Chou, Chang-Hung

2012-11-01

Microsatellite loci were developed from Imperata cylindrica, a traditional medicinal herb in Asia and among the top 10 worst invasive weeds in the world, to aid in the identification of the limits of asexual clonal individuals. A total of 21 microsatellite markers, including 18 polymorphic and three monomorphic loci, were developed from I. cylindrica using a magnetic bead enrichment protocol. The primers amplified dinucleotide, trinucleotide, and complex repeats. The number of alleles ranged from one to 19 per locus, with an observed heterozygosity ranging from 0.09 to 1.00. Several loci deviated significantly from the within-population Hardy-Weinberg equilibrium as a result of asexual clonal reproduction. These polymorphic markers should be useful tools in further studies on the identification of the range of clonal reproduction units and the selection and classification of the medicinal cultivar.

A broad survey of recombination in animal mitochondria.

PubMed

Piganeau, Gwenaël; Gardner, Michael; Eyre-Walker, Adam

2004-12-01

Recombination in mitochondrial DNA (mtDNA) remains a controversial topic. Here we present a survey of 279 animal mtDNA data sets, of which 12 were from asexual species. Using four separate tests, we show that there is widespread evidence of recombination; for one test as many as 14.2% of the data sets reject a model of clonal inheritance and in several data sets, including primates, the recombinants can be identified visually. We show that none of the tests give significant results for obligate clonal species (apomictic pathogens) and that the sexual species show significantly greater evidence of recombination than asexual species. For some data sets, such as Macaca nemestrina, additional data sets suggest that the recombinants are not artifacts. For others, it cannot be determined whether the recombinants are real or produced by laboratory error. Either way, the results have important implications for how mtDNA is sequenced and used.

Mannosyltransferase is required for cell wall biosynthesis, morphology and control of asexual development in Neurospora crassa.

PubMed

Bowman, Shaun M; Piwowar, Amy; Ciocca, Maria; Free, Stephen J

2005-01-01

Two Neurospora mutants with a phenotype that includes a tight colonial growth pattern, an inability to form conidia and an inability to form protoperithecia have been isolated and characterized. The relevant mutations were mapped to the same locus on the sequenced Neurospora genome. The mutations responsible for the mutant phenotype then were identified by examining likely candidate genes from the mutant genomes at the mapped locus with PCR amplification and a sequencing assay. The results demonstrate that a map and sequence strategy is a feasible way to identify mutant genes in Neurospora. The gene responsible for the phenotype is a putative alpha-1,2-mannosyltransferase gene. The mutant cell wall has an altered composition demonstrating that the gene functions in cell wall biosynthesis. The results demonstrate that the mnt-1 gene is required for normal cell wall biosynthesis, morphology and for the regulation of asexual development.

Expanding the Species and Chemical Diversity of Penicillium Section Cinnamopurpurea

PubMed Central

Peterson, Stephen W.; Jurjević, Željko; Frisvad, Jens C.

2015-01-01

A set of isolates very similar to or potentially conspecific with an unidentified Penicillium isolate NRRL 735, was assembled using a BLAST search of ITS similarity among described (GenBank) and undescribed Penicillium isolates in our laboratories. DNA was amplified from six loci of the assembled isolates and sequenced. Two species in section Cinnamopurpurea are self-compatible sexual species, but the asexual species had polymorphic loci suggestive of sexual reproduction and variation in conidium size suggestive of ploidy level differences typical of heterothallism. Accordingly we use genealogical concordance analysis, a technique valid only in heterothallic organisms, for putatively asexual species. Seven new species were revealed in the analysis and are described here. Extrolite analysis showed that two of the new species, P. colei and P. monsserratidens produce the mycotoxin citreoviridin that has demonstrated pharmacological activity against human lung tumors. These isolates could provide leads in pharmaceutical research. PMID:25853891

Chemical signatures and new drug targets for gametocytocidal drug development

NASA Astrophysics Data System (ADS)

Sun, Wei; Tanaka, Takeshi Q.; Magle, Crystal T.; Huang, Wenwei; Southall, Noel; Huang, Ruili; Dehdashti, Seameen J.; McKew, John C.; Williamson, Kim C.; Zheng, Wei

2014-01-01

Control of parasite transmission is critical for the eradication of malaria. However, most antimalarial drugs are not active against P. falciparum gametocytes, responsible for the spread of malaria. Consequently, patients can remain infectious for weeks after the clearance of asexual parasites and clinical symptoms. Here we report the identification of 27 potent gametocytocidal compounds (IC50 < 1 μM) from screening 5,215 known drugs and compounds. All these compounds were active against three strains of gametocytes with different drug sensitivities and geographical origins, 3D7, HB3 and Dd2. Cheminformatic analysis revealed chemical signatures for P. falciparum sexual and asexual stages indicative of druggability and suggesting potential targets. Torin 2, a top lead compound (IC50 = 8 nM against gametocytes in vitro), completely blocked oocyst formation in a mouse model of transmission. These results provide critical new leads and potential targets to expand the repertoire of malaria transmission-blocking reagents.

The powdery mildews: a review of the world's most familiar (yet poorly known) plant pathogens.

PubMed

Glawe, Dean A

2008-01-01

The past decade has seen fundamental changes in our understanding of powdery mildews (Erysiphales). Research on molecular phylogeny demonstrated that Erysiphales are Leotiomycetes (inoperculate discomycetes) rather than Pyrenomycetes or Plectomycetes. Life cycles are surprisingly variable, including both sexual and asexual states, or only sexual states, or only asexual states. At least one species produces dematiaceous conidia. Analyses of rDNA sequences indicate that major lineages are more closely correlated with anamorphic features such as conidial ontogeny and morphology than with teleomorph features. Development of molecular clock models is enabling researchers to reconstruct patterns of coevolution and host-jumping, as well as ancient migration patterns. Geographic distributions of some species appear to be increasing rapidly but little is known about species diversity in many large areas, including North America. Powdery mildews may already be responding to climate change, suggesting they may be useful models for studying effects of climate change on plant diseases.