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Sample records for galapagoensis host genetic

  1. Some laelapine mites (Acari: Laelapidae) ectoparasitic on small mammals in the Galapagos Islands, including a new species of Gigantolaelaps from Aegialomys galapagoensis.

    PubMed

    Gettinger, Donald; Martins-Hatano, Fernanda; Gardner, Scott L

    2011-08-01

    A collection of laelapine mites from small mammals in the Galapagos Islands are identified and their host distributions reviewed. Two species of native rodents, Aegialomys galapagoensis and Nesoryzomys narboroughii, were infested only with laelapine species typical of Neotropical oryzomyine rodents; Rattus rattus was infested with Laelaps nuttalli, a host-specific ectoparasite endemic to Old World Rattus. A synopsis of Gigantolaelaps Fonseca is provided and we describe a new laelapine mite, Gigantolaelaps aegialomys n. sp., from the pelage of the rodent A. galapagoensis on Santa Fe Island. The new species has strong morphological affinities with a subgroup of Gigantolaelaps associated with a group of semiaquatic oryzomyine rodents ( Holochilus, Nectomys, Sooretamys, Pseudoryzomys , Oryzomys palustris). The other nominal species of this group, Gigantolaelaps mattogrossensis (Fonseca, 1935) and Gigantolaelaps goyanensis Fonseca, 1939 , are characterized by 10 setae on Tibia IV, large metapodal shields, and spiniform setae on Coxae I. Gigantolaelaps aegialomys is distinguished from these species by a lack of clearly spiniform setae on Coxa I, with setiform distal seta longer than the proximal; metapodal shields about the same size as the stigma; less than 100 µm separating the first pair of sternal setae.

  2. Treatment of candidiasis: insights from host genetics.

    PubMed

    Delsing, Corine E; Bleeker-Rovers, Chantal P; Kullberg, Bart-Jan; Netea, Mihai G

    2012-08-01

    Candida species are major causes of mucosal and invasive infections, leading to substantial morbidity and mortality. Despite the development of new classes of antifungal drugs, mortality in patients with systemic candidiasis remains high. Host-Candida interaction plays an important role in effective elimination of the pathogen. Genetic studies have rendered important insights into antifungal host defense and have identified potential targets for adjunctive therapy. In this article, the authors review the genetic variations in the host defense to Candida and their implications for the treatment of mucosal and systemic candidiasis.

  3. Phylogeography of the Galápagos hawk (Buteo galapagoensis): a recent arrival to the Galápagos Islands.

    PubMed

    Bollmer, Jennifer L; Kimball, Rebecca T; Whiteman, Noah Kerness; Sarasola, José Hernán; Parker, Patricia G

    2006-04-01

    Galápagos hawks (Buteo galapagoensis) are one of the most inbred bird species in the world, living in small, isolated island populations. We used mitochondrial sequence and nuclear minisatellite data to describe relationships among Galápagos hawk populations and their colonization history. We sampled 10 populations (encompassing the entire current species range of nine islands and one extirpated population), as well as the Galápagos hawk's closest mainland relative, the Swainson's hawk (B. swainsoni). There was little sequence divergence between Galápagos and Swainson's hawks (only 0.42% over almost 3kb of data), indicating that the hawks colonized Galápagos very recently, likely less than 300,000 years ago, making them the most recent arrivals of the studied taxa. There were only seven, closely related Galápagos hawk haplotypes, with most populations being monomorphic. The mitochondrial and minisatellite data together indicated a general pattern of rapid population expansion followed by genetic isolation of hawk breeding populations. The recent arrival, genetic isolation, and phenotypic differentiation among populations suggest that the Galápagos hawk, a rather new species itself, is in the earliest stages of further divergence.

  4. GENETICS OF HOST RANGE IN LEPIDOPTERA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genetic basis of complex, ecologically relevant traits is not well known for any organism. The question is particularly compelling where closely-related species have diverged radically in their adaptation to the environment. Differences in host plant use among moths and butterflies often provi...

  5. Giardia duodenalis genetic assemblages and hosts

    PubMed Central

    Heyworth, Martin F.

    2016-01-01

    Techniques for sub-classifying morphologically identical Giardia duodenalis trophozoites have included comparisons of the electrophoretic mobility of enzymes and of chromosomes, and sequencing of genes encoding β-giardin, triose phosphate isomerase, the small subunit of ribosomal RNA and glutamate dehydrogenase. To date, G. duodenalis organisms have been sub-classified into eight genetic assemblages (designated A–H). Genotyping of G. duodenalis organisms isolated from various hosts has shown that assemblages A and B infect the largest range of host species, and appear to be the main (or possibly only) G. duodenalis assemblages that undeniably infect human subjects. In at least some cases of assemblage A or B infection in wild mammals, there is suggestive evidence that the infection had resulted from environmental contamination by G. duodenalis cysts of human origin. PMID:26984116

  6. Impact of host genetic polymorphisms on vaccine induced antibody response

    PubMed Central

    Linnik, Janina E.; Egli, Adrian

    2016-01-01

    ABSTRACT Many host- and vaccine-specific factors modulate an antibody response. Host genetic polymorphisms, in particular, modulate the immune response in multiple ways on different scales. This review article describes how information on host genetic polymorphisms and corresponding immune cascades may be used to generate personalized vaccine strategies to optimize the antibody response. PMID:26809773

  7. Genetic architecture underlying host choice differentiation in the sympatric host races of Lochmaea capreae leaf beetles.

    PubMed

    Soudi, Shaghayegh; Reinhold, Klaus; Engqvist, Leif

    2016-04-01

    Speciation in herbivorous insects has received considerable attention during the last few decades. Much of this group's diversity originates from adaptive population divergence onto different host plants, which often involves the evolution of specialized patterns of host choice behaviour. Differences in host choice often translates directly into divergence in mating sites, and therefore positive assortative mating will be created which will act as a strong barrier to gene flow. In this study, we first explored whether host choice is a genetically determined trait in the sympatric willow and birch host races of the leaf feeding beetle Lochmaea capreae, or whether larval experience influences adult host choice. Once we had established that host choice is a genetically based trait we determined its genetic architecture. To achieve this, we employed a reciprocal transplant design in which offspring from pure willow and birch cross-types, F1, F2 and backcrosses were raised on each host plant and their preference was determined upon reaching adulthood. We then applied joint-scaling analysis to uncover the genetic architecture of host preference. Our results suggest that rearing host does not have a pronounced effect on adult's host choice; rather the segregation pattern implies the existence of genetic loci affecting host choice in these host races. The joint-scaling analysis revealed that population differences in host choice are mainly influenced by the contribution of additive genetic effects and also maternally inherited cytoplasmic effects. We explore the implications of our findings for evolutionary dynamics of sympatric host race formation and speciation.

  8. Correlations of Host Genetics and Gut Microbiome Composition

    PubMed Central

    Dąbrowska, Krystyna; Witkiewicz, Wojciech

    2016-01-01

    The human gut microbiome has a considerable impact on host health. The long list of microbiome-related health disorders raises the question of what in fact determines microbiome composition. In this review we sought to understand how the host itself impacts the structure of the gut microbiota population, specifically by correlations of host genetics and gut microbiome composition. Host genetic profile has been linked to differences in microbiome composition, thus suggesting that host genetics can shape the gut microbiome of the host. However, cause-consequence mechanisms behind these links are still unclear. A survey of the possible mechanisms allowing host genetics to shape microbiota composition in the gut demonstrated the major role of metabolic functions and the immune system. A considerable impact of other factors, such as diet, may outweigh the effects of host genetic background. More studies are necessary for good understanding of the relations between the host genetic profile, gut microbiome composition, and host health. According to the idea of personalized medicine, patient-tailored management of microbiota content remains a fascinating area for further inquiry. PMID:27625642

  9. Genetic differentiation among sympatric cuckoo host races: males matter.

    PubMed

    Fossøy, Frode; Antonov, Anton; Moksnes, Arne; Røskaft, Eivin; Vikan, Johan R; Møller, Anders P; Shykoff, Jacqui A; Stokke, Bård G

    2011-06-07

    Generalist parasites regularly evolve host-specific races that each specialize on one particular host species. Many host-specific races originate from geographically structured populations where local adaptations to different host species drive the differentiation of distinct races. However, in sympatric populations where several host races coexist, gene flow could potentially disrupt such host-specific adaptations. Here, we analyse genetic differentiation among three sympatrically breeding host races of the brood-parasitic common cuckoo, Cuculus canorus. In this species, host-specific adaptations are assumed to be controlled by females only, possibly via the female-specific W-chromosome, thereby avoiding that gene flow via males disrupts local adaptations. Although males were more likely to have offspring in two different host species (43% versus 7%), they did not have significantly more descendants being raised outside their putative foster species than females (9% versus 2%). We found significant genetic differentiation for both biparentally inherited microsatellite DNA markers and maternally inherited mitochondrial DNA markers. To our knowledge, this is the first study that finds significant genetic differentiation in biparentally inherited markers among cuckoo host-specific races. Our results imply that males also may contribute to the evolution and maintenance of the different races, and hence that the genes responsible for egg phenotype may be found on autosomal chromosomes rather than the female-specific W-chromosome as previously assumed.

  10. Health evaluation of Galapagos Hawks (Buteo galapagoensis) on Santiago Island, Galapagos.

    PubMed

    Deem, Sharon L; Rivera-Parra, Jose Luis; Parker, Patricia G

    2012-01-01

    Galapagos Hawks (Buteo galapagoensis), the only endemic, diurnal raptor species in Galapagos, are currently distributed on eight Galapagos Islands having been extirpated from three of the human-inhabited islands. In January 2009, we performed health assessments of 89 Galapagos Hawks on Santiago Island, Galapagos. Four of the 89 Galapagos Hawks (4%) evaluated had physical abnormalities. Blood parameters did not differ between males and females, except for aspartate transaminase values, which were significantly higher in females than males. No Galapagos Hawks tested positive for antibodies to avian encephalitis virus, Marek virus, and paramyxovirus-1 or to haemosporidian antigen. Chlamydophila psittaci antigen was detected in 2 of 86 Galapagos Hawks (2%), with 24 of 43 Galapagos Hawks (56%) antibody-positive for avian adenovirus-1 and 1 of 48 Galapagos Hawks (2%) antibody positive for Toxoplasma gondii. There were no significant differences in infectious disease results based on sex. This study contributes to the understanding of the health status of the Galapagos Hawk and to the establishment of baseline information for the species.

  11. Host Genetic and Environmental Effects on Mouse Cecum Microbiota

    SciTech Connect

    Campbell, James H; Foster, Carmen M; Vishnivetskaya, Tatiana A; Campbell, Alisha G; Yang, Zamin Koo; Wymore, Ann; Palumbo, Anthony Vito; Podar, Mircea

    2012-01-01

    The mammalian gut harbors complex and variable microbial communities, across both host phylogenetic space and conspecific individuals. A synergy of host genetic and environmental factors shape these communities and account for their variability, but their individual contributions and the selective pressures involved are still not well understood. We employed barcoded pyrosequencing of V1-2 and V4 regions of bacterial small subunit ribosomal RNA genes to characterize the effects of host genetics and environment on cecum assemblages in 10 genetically distinct, inbred mouse strains. Eight of these strains are the foundation of the Collaborative Cross (CC), a panel of mice derived from a genetically diverse set of inbred founder strains, designed specifically for complex trait analysis. Diversity of gut microbiota was characterized by complementing phylogenetic and distance-based, sequence-clustering approaches. Significant correlations were found between the mouse strains and their gut microbiota, reflected by distinct bacterial communities. Cohabitation and litter had a reduced, although detectable effect, and the microbiota response to these factors varied by strain. We identified bacterial phylotypes that appear to be discriminative and strain-specific to each mouse line used. Cohabitation of different strains of mice revealed an interaction of host genetic and environmental factors in shaping gut bacterial consortia, in which bacterial communities became more similar but retained strain specificity. This study provides a baseline analysis of intestinal bacterial communities in the eight CC progenitor strains and will be linked to integrated host genotype, phenotype and microbiota research on the resulting CC panel.

  12. Does genetic diversity limit disease spread in natural host populations?

    PubMed Central

    King, K C; Lively, C M

    2012-01-01

    It is a commonly held view that genetically homogenous host populations are more vulnerable to infection than genetically diverse populations. The underlying idea, known as the ‘monoculture effect,' is well documented in agricultural studies. Low genetic diversity in the wild can result from bottlenecks (that is, founder effects), biparental inbreeding or self-fertilization, any of which might increase the risk of epidemics. Host genetic diversity could buffer populations against epidemics in nature, but it is not clear how much diversity is required to prevent disease spread. Recent theoretical and empirical studies, particularly in Daphnia populations, have helped to establish that genetic diversity can reduce parasite transmission. Here, we review the present theoretical work and empirical evidence, and we suggest a new focus on finding ‘diversity thresholds.' PMID:22713998

  13. Standing genetic variation in host preference for mutualist microbial symbionts

    PubMed Central

    Simonsen, Anna K.; Stinchcombe, John R.

    2014-01-01

    Many models of mutualisms show that mutualisms are unstable if hosts lack mechanisms enabling preferential associations with mutualistic symbiotic partners over exploitative partners. Despite the theoretical importance of mutualism-stabilizing mechanisms, we have little empirical evidence to infer their evolutionary dynamics in response to exploitation by non-beneficial partners. Using a model mutualism—the interaction between legumes and nitrogen-fixing soil symbionts—we tested for quantitative genetic variation in plant responses to mutualistic and exploitative symbiotic rhizobia in controlled greenhouse conditions. We found significant broad-sense heritability in a legume host's preferential association with mutualistic over exploitative symbionts and selection to reduce frequency of associations with exploitative partners. We failed to detect evidence that selection will favour the loss of mutualism-stabilizing mechanisms in the absence of exploitation, as we found no evidence for a fitness cost to the host trait or indirect selection on genetically correlated traits. Our results show that genetic variation in the ability to preferentially reduce associations with an exploitative partner exists within mutualisms and is under selection, indicating that micro-evolutionary responses in mutualism-stabilizing traits in the face of rapidly evolving mutualistic and exploitative symbiotic bacteria can occur in natural host populations. PMID:25355477

  14. The genetic predisposition and the interplay of host genetics and gut microbiome in Crohn disease.

    PubMed

    Jianzhong, Hu

    2014-12-01

    Extensive genetic studies have identified more than 140 loci predisposing to Crohn disease (CD). Several major CD susceptibility genes have been shown to impair biological function with regard to immune response to recognizing and clearance of bacterial infection. Recent human microbiome studies suggest that the gut microbiome composition is differentiated in carriers of many risk variants of major CD susceptibility genes. This interplay between host genetics and its associated gut microbiome may play an essential role in the pathogenesis of CD. The ongoing microbiome research is aimed to investigate the detailed host genetics-microbiome interacting mechanism.

  15. Plasmodium genetic loci linked to host cytokine and chemokine responses

    PubMed Central

    Pattaradilokrat, Sittiporn; Li, Jian; Wu, Jian; Qi, Yanwei; Eastman, Richard T.; Zilversmit, Martine; Nair, Sethu C.; Huaman, Maria Cecilia; Quinones, Mariam; Jiang, Hongying; Li, Na; Zhu, Jun; Zhao, Keji; Kaneko, Osamu; Long, Carole A.; Su, Xin-zhuan

    2014-01-01

    Both host and parasite factors contribute to disease severity of malaria infection; however, the molecular mechanisms responsible for the disease and the host-parasite interactions involved remain largely unresolved. To investigate effects of parasite factors on host immune responses and pathogenesis, we measured levels of plasma cytokines/chemokines (CC) and growth rates in mice infected with two Plasmodium yoelii strains having different virulence phenotypes and in progeny from a genetic cross of the two parasites. Quantitative trait loci (QTL) analysis linked levels of many CCs, particularly IL-1β, IP-10, IFN-γ, MCP-1, and MIG, and early parasite growth rate to loci on multiple parasite chromosomes, including chromosomes 7, 9, 10, 12, and 13. Comparison of the genome sequences spanning the mapped loci revealed various candidate genes. The loci on chromosome 7 and 13 had significant (p < 0.005) additive effects on IL-1β, IL-5, and IP-10 responses, and the chromosome 9 and 12 loci had significant (p = 0.017) interaction. Infection of knockout mice showed critical roles of MCP-1 and IL-10 in parasitemia control and host mortality. These results provide important information for better understanding of malaria pathogenesis and can be used to examine the role of these factors in human malaria infection. PMID:24452266

  16. Plasmodium genetic loci linked to host cytokine and chemokine responses.

    PubMed

    Pattaradilokrat, S; Li, J; Wu, J; Qi, Y; Eastman, R T; Zilversmit, M; Nair, S C; Huaman, M C; Quinones, M; Jiang, H; Li, N; Zhu, J; Zhao, K; Kaneko, O; Long, C A; Su, X-z

    2014-01-01

    Both host and parasite factors contribute to disease severity of malaria infection; however, the molecular mechanisms responsible for the disease and the host-parasite interactions involved remain largely unresolved. To investigate the effects of parasite factors on host immune responses and pathogenesis, we measured levels of plasma cytokines/chemokines (CCs) and growth rates in mice infected with two Plasmodium yoelii strains having different virulence phenotypes and in progeny from a genetic cross of the two parasites. Quantitative trait loci (QTL) analysis linked levels of many CCs, particularly IL-1β, IP-10, IFN-γ, MCP-1 and MIG, and early parasite growth rate to loci on multiple parasite chromosomes, including chromosomes 7, 9, 10, 12 and 13. Comparison of the genome sequences spanning the mapped loci revealed various candidate genes. The loci on chromosomes 7 and 13 had significant (P<0.005) additive effects on IL-1β, IL-5 and IP-10 responses, and the chromosome 9 and 12 loci had significant (P=0.017) interaction. Infection of knockout mice showed critical roles of MCP-1 and IL-10 in parasitemia control and host mortality. These results provide important information for a better understanding of malaria pathogenesis and can be used to examine the role of these factors in human malaria infection.

  17. The genetics of host-virus coevolution in invertebrates.

    PubMed

    Obbard, Darren J; Dudas, Gytis

    2014-10-01

    Although viral infection and antiviral defence are ubiquitous, genetic data are currently unavailable from the vast majority of animal phyla-potentially biasing our overall perspective of the coevolutionary process. Rapid adaptive evolution is seen in some insect antiviral genes, consistent with invertebrate-virus 'arms-race' coevolution, but equivalent signatures of selection are hard to detect in viruses. We find that, despite the large differences in vertebrate, invertebrate, and plant immune responses, comparison of viral evolution fails to identify any difference among these hosts in the impact of positive selection. The best evidence for invertebrate-virus coevolution is currently provided by large-effect polymorphisms for host resistance and/or viral evasion, as these often appear to have arisen and spread recently, and can be favoured by virus-mediated selection.

  18. Association between host's genetic diversity and parasite burden in damselflies.

    PubMed

    Kaunisto, K M; Viitaniemi, H M; Leder, E H; Suhonen, J

    2013-08-01

    Recent research indicates that low genetic variation in individuals can increase susceptibility to parasite infection, yet evidence from natural invertebrate populations remains scarce. Here, we studied the relationship between genetic heterozygosity, measured as AFLP-based inbreeding coefficient fAFLP , and gregarine parasite burden from eleven damselfly, Calopteryx splendens, populations. We found that in the studied populations, 5-92% of males were parasitized by endoparasitic gregarines (Apicomplexa: Actinocephalidae). Number of parasites ranged from none to 47 parasites per male, and parasites were highly aggregated in a few hosts. Mean individual fAFLP did not differ between populations. Moreover, we found a positive association between individual's inbreeding coefficient and parasite burden. In other words, the more homozygous the individual, the more parasites it harbours. Thus, parasites are likely to pose strong selection pressure against inbreeding and homozygosity. Our results support the heterozygosity-fitness correlation hypothesis, which suggests the importance of heterozygosity for an individual's pathogen resistance.

  19. Genetic architecture of resistance in Daphnia hosts against two species of host-specific parasites

    PubMed Central

    Routtu, J; Ebert, D

    2015-01-01

    Understanding the genetic architecture of host resistance is key for understanding the evolution of host–parasite interactions. Evolutionary models often assume simple genetics based on few loci and strong epistasis. It is unknown, however, whether these assumptions apply to natural populations. Using a quantitative trait loci (QTL) approach, we explore the genetic architecture of resistance in the crustacean Daphnia magna to two of its natural parasites: the horizontally transmitted bacterium Pasteuria ramosa and the horizontally and vertically transmitted microsporidium Hamiltosporidium tvaerminnensis. These two systems have become models for studies on the evolution of host–parasite interactions. In the QTL panel used here, Daphnia's resistance to P. ramosa is controlled by a single major QTL (which explains 50% of the observed variation). Resistance to H. tvaerminnensis horizontal infections shows a signature of a quantitative trait based in multiple loci with weak epistatic interactions (together explaining 38% variation). Resistance to H. tvaerminnensis vertical infections, however, shows only one QTL (explaining 13.5% variance) that colocalizes with one of the QTLs for horizontal infections. QTLs for resistance to Pasteuria and Hamiltosporidium do not colocalize. We conclude that the genetics of resistance in D. magna are drastically different for these two parasites. Furthermore, we infer that based on these and earlier results, the mechanisms of coevolution differ strongly for the two host–parasite systems. Only the Pasteuria–Daphnia system is expected to follow the negative frequency-dependent selection (Red Queen) model. How coevolution works in the Hamiltosporidium–Daphnia system remains unclear. PMID:25335558

  20. Host - hepatitis C viral interactions: The role of genetics.

    PubMed

    Heim, Markus H; Bochud, Pierre-Yves; George, Jacob

    2016-10-01

    Hepatitis C virus (HCV) is a major cause of chronic viral hepatitis that can lead to cirrhosis and hepatocellular carcinoma. Only a minority of patients can clear the virus spontaneously. Elimination of HCV during acute infection correlates with a rapid induction of innate, especially interferon (IFN)-induced genes, and a delayed induction of adaptive immune responses. There is a strong association between genetic variants in the IFNλ (IL28B) locus with the rate of spontaneous clearance. Individuals with the ancestral IFNλ4 allele capable of producing a fully active IFNλ4 are paradoxically not able to clear HCV in the acute phase and develop chronic hepatitis C (CHC) with more than 90% probability. In the chronic phase of HCV infection, the wild-type IFNλ4 genotype is strongly associated with an induction of hundreds of classical type I/type III IFN stimulated genes in hepatocytes. However, the activation of the endogenous IFN system in the liver is ineffective in clearing HCV, and is even associated with impaired therapeutic responses to pegylated (Peg)IFNα containing treatments. While the role of genetic variation in the IFNλ locus to the outcome of CHC treatment has declined, it is clear that variation not only at this locus, but also at other loci, modulate clinically important liver phenotypes, including inflammation, fibrosis progression and the development of hepatocellular cancer. In this review, we summarize current knowledge about the role of genetics in the host response to viral hepatitis and the potential future evolution of knowledge in understanding host-viral interactions.

  1. Host dispersal as the driver of parasite genetic structure: a paradigm lost?

    PubMed

    Mazé-Guilmo, Elise; Blanchet, Simon; McCoy, Karen D; Loot, Géraldine

    2016-03-01

    Understanding traits influencing the distribution of genetic diversity has major ecological and evolutionary implications for host-parasite interactions. The genetic structure of parasites is expected to conform to that of their hosts, because host dispersal is generally assumed to drive parasite dispersal. Here, we used a meta-analysis to test this paradigm and determine whether traits related to host dispersal correctly predict the spatial co-distribution of host and parasite genetic variation. We compiled data from empirical work on local adaptation and host-parasite population genetic structure from a wide range of taxonomic groups. We found that genetic differentiation was significantly lower in parasites than in hosts, suggesting that dispersal may often be higher for parasites. A significant correlation in the pairwise genetic differentiation of hosts and parasites was evident, but surprisingly weak. These results were largely explained by parasite reproductive mode, the proportion of free-living stages in the parasite life cycle and the geographical extent of the study; variables related to host dispersal were poor predictors of genetic patterns. Our results do not dispel the paradigm that parasite population genetic structure depends on host dispersal. Rather, we highlight that alternative factors are also important in driving the co-distribution of host and parasite genetic variation.

  2. Dengue and dengue haemorrhagic fever: implications of host genetics.

    PubMed

    Chaturvedi, Umeshc; Nagar, Rachna; Shrivastava, Richa

    2006-07-01

    Little is known of the role of human leucocyte antigen (HLA) alleles or non-HLA alleles in determining resistance, susceptibility or the severity of acute viral infections. Dengue fever (DF) and dengue haemorrhagic fever (DHF) are suitable models for immunogenetic studies, yet only superficial efforts have been made to study dengue disease to date. DF and DHF can be caused by both primary and secondary infection by any of the four serotypes of the dengue virus. Differences in host susceptibility to infectious disease and disease severity cannot be attributed solely to the virus virulence. Variations in immune response, often associated with polymorphism in the human genome, can now be detected. Data on the influence of human genes in DF and DHF are discussed here in relation to (1) associations between HLA polymorphism and dengue disease susceptibility or resistance, (2) protective alleles influencing progression to severe disease, (3) alleles restricting CD4(+) and CD8(+) T lymphocytes, and (4) non-HLA genetic factors that may contribute to DHF evolution. Recent discoveries regarding genetic associations in other viral infections may provide clues to understanding the development of end-stage complications in dengue disease. The scanty positive data presented here indicate a need for detailed genetic studies in different ethnic groups in different countries during the acute phase of DF and DHF on a larger number of patients.

  3. Genetic and environmental control of host-gut microbiota interactions

    PubMed Central

    Org, Elin; Parks, Brian W.; Joo, Jong Wha J.; Emert, Benjamin; Schwartzman, William; Kang, Eun Yong; Mehrabian, Margarete; Pan, Calvin; Knight, Rob; Gunsalus, Robert; Drake, Thomas A.; Eskin, Eleazar; Lusis, Aldons J.

    2015-01-01

    Genetics provides a potentially powerful approach to dissect host-gut microbiota interactions. Toward this end, we profiled gut microbiota using 16s rRNA gene sequencing in a panel of 110 diverse inbred strains of mice. This panel has previously been studied for a wide range of metabolic traits and can be used for high-resolution association mapping. Using a SNP-based approach with a linear mixed model, we estimated the heritability of microbiota composition. We conclude that, in a controlled environment, the genetic background accounts for a substantial fraction of abundance of most common microbiota. The mice were previously studied for response to a high-fat, high-sucrose diet, and we hypothesized that the dietary response was determined in part by gut microbiota composition. We tested this using a cross-fostering strategy in which a strain showing a modest response, SWR, was seeded with microbiota from a strain showing a strong response, A×B19. Consistent with a role of microbiota in dietary response, the cross-fostered SWR pups exhibited a significantly increased response in weight gain. To examine specific microbiota contributing to the response, we identified various genera whose abundance correlated with dietary response. Among these, we chose Akkermansia muciniphila, a common anaerobe previously associated with metabolic effects. When administered to strain A×B19 by gavage, the dietary response was significantly blunted for obesity, plasma lipids, and insulin resistance. In an effort to further understand host-microbiota interactions, we mapped loci controlling microbiota composition and prioritized candidate genes. Our publicly available data provide a resource for future studies. PMID:26260972

  4. Continuous Influx of Genetic Material from Host to Virus Populations

    PubMed Central

    Gilbert, Clément; Peccoud, Jean; Chateigner, Aurélien; Moumen, Bouziane

    2016-01-01

    Many genes of large double-stranded DNA viruses have a cellular origin, suggesting that host-to-virus horizontal transfer (HT) of DNA is recurrent. Yet, the frequency of these transfers has never been assessed in viral populations. Here we used ultra-deep DNA sequencing of 21 baculovirus populations extracted from two moth species to show that a large diversity of moth DNA sequences (n = 86) can integrate into viral genomes during the course of a viral infection. The majority of the 86 different moth DNA sequences are transposable elements (TEs, n = 69) belonging to 10 superfamilies of DNA transposons and three superfamilies of retrotransposons. The remaining 17 sequences are moth sequences of unknown nature. In addition to bona fide DNA transposition, we uncover microhomology-mediated recombination as a mechanism explaining integration of moth sequences into viral genomes. Many sequences integrated multiple times at multiple positions along the viral genome. We detected a total of 27,504 insertions of moth sequences in the 21 viral populations and we calculate that on average, 4.8% of viruses harbor at least one moth sequence in these populations. Despite this substantial proportion, no insertion of moth DNA was maintained in any viral population after 10 successive infection cycles. Hence, there is a constant turnover of host DNA inserted into viral genomes each time the virus infects a moth. Finally, we found that at least 21 of the moth TEs integrated into viral genomes underwent repeated horizontal transfers between various insect species, including some lepidopterans susceptible to baculoviruses. Our results identify host DNA influx as a potent source of genetic diversity in viral populations. They also support a role for baculoviruses as vectors of DNA HT between insects, and call for an evaluation of possible gene or TE spread when using viruses as biopesticides or gene delivery vectors. PMID:26829124

  5. Probing Genetic Control of Swine Responses to PRRSV Infection: Current Progress of the PRRS Host Genetics Consortium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Understanding the role of host genetics in resistance to porcine reproductive and respiratory syndrome virus (PRRSV) infection, and the effects of PRRS on pig health and related growth, are goals of the PRRS Host Genetics Consortium (PHGC). Methods: The project uses a nursery pig model ...

  6. Mobile Introns Shape the Genetic Diversity of Their Host Genes

    PubMed Central

    Repar, Jelena; Warnecke, Tobias

    2017-01-01

    Self-splicing introns populate several highly conserved protein-coding genes in fungal and plant mitochondria. In fungi, many of these introns have retained their ability to spread to intron-free target sites, often assisted by intron-encoded endonucleases that initiate the homing process. Here, leveraging population genomic data from Saccharomyces cerevisiae, Schizosaccharomyces pombe, and Lachancea kluyveri, we expose nonrandom patterns of genetic diversity in exons that border self-splicing introns. In particular, we show that, in all three species, the density of single nucleotide polymorphisms increases as one approaches a mobile intron. Through multiple lines of evidence, we rule out relaxed purifying selection as the cause of uneven nucleotide diversity. Instead, our findings implicate intron mobility as a direct driver of host gene diversity. We discuss two mechanistic scenarios that are consistent with the data: either endonuclease activity and subsequent error-prone repair have left a mutational footprint on the insertion environment of mobile introns or nonrandom patterns of genetic diversity are caused by exonic coconversion, which occurs when introns spread to empty target sites via homologous recombination. Importantly, however, we show that exonic coconversion can only explain diversity gradients near intron–exon boundaries if the conversion template comes from outside the population. In other words, there must be pervasive and ongoing horizontal gene transfer of self-splicing introns into extant fungal populations. PMID:28193728

  7. Population genetic structure of a three-host tick, Amblyomma dissimile, in eastern Venezuela.

    PubMed

    Lampo, M; Rangel, Y; Mata, A

    1998-12-01

    Patterns of genetic variation for the tick Amblyomma dissimile were analyzed from a total of 200 ticks collected on 12 toads (Bufo marinus), 14 snakes (Boa constrictor), and 8 lizards (Iguana iguana) at 11 localities. The analyses were performed on electrophoretic data from 8 isozyme loci. Mean heterozygosity per locus was 6% (+/-3.1) per population. Differences in allelic frequencies among ticks from different individual hosts were the major source of genetic variability in this study. Host species was a smaller source of genetic variation. Genetic distances between localities varied according to which host species was present in each locality, and these appeared to be related to the extent of habitat overlap between host species. The smallest genetic distances between samples from different host species were recorded for I. iguana and B. constrictor. In contrast, the genetic distances between tick samples from B. marinus and either of the reptile species were significantly larger than between tick samples from this amphibian species. Ecological variables or the geographic distance did not explain the local patterns of differentiation observed in A. dissimile. Major genetic differences between island and mainland sites (0.03702) suggested an association between genetic distances and geographic isolation. The consistency between patterns of genetic variation and those of host home range overlap suggests that host dispersion is the main force structuring the genetic variation within this tick species.

  8. Cryptosporidium within-host genetic diversity: systematic bibliographical search and narrative overview.

    PubMed

    Grinberg, Alex; Widmer, Giovanni

    2016-07-01

    Knowledge of the within-host genetic diversity of a pathogen often has broad implications for disease management. Cryptosporidium protozoan parasites are among the most common causative agents of infectious diarrhoea. Current limitations of in vitro culture impose the use of uncultured isolates obtained directly from the hosts as operational units of Cryptosporidium genotyping. The validity of this practice is centred on the assumption of genetic homogeneity of the parasite within the host, and genetic studies often take little account of the within-host genetic diversity of Cryptosporidium. Yet, theory and experimental evidence contemplate genetic diversity of Cryptosporidium at the within-host scale, but this diversity is not easily identified by genotyping methods ill-suited for the resolution of DNA mixtures. We performed a systematic bibliographical search of the occurrence of within-host genetic diversity of Cryptosporidium parasites in epidemiological samples, between 2005 and 2015. Our results indicate that genetic diversity at the within-host scale, in the form of mixed species or intra-species diversity, has been identified in a large number (n=55) of epidemiological surveys of cryptosporidiosis in variable proportions, but has often been treated as a secondary finding and not analysed. As in malaria, there are indications that the scale of this diversity varies between geographical regions, perhaps depending on the prevailing transmission pathways. These results provide a significant knowledge base from which to draw alternative population genetic structure models, some of which are discussed in this paper.

  9. Postmating isolation and genetically variable host use in ecologically divergent host forms of Neochlamisus bebbianae leaf beetles.

    PubMed

    Egan, S P; Janson, E M; Brown, C G; Funk, D J

    2011-10-01

    Ecological speciation studies have more thoroughly addressed premating than postmating reproductive isolation. This study examines multiple postmating barriers between host forms of Neochlamisus bebbianae leaf beetles that specialize on Acer and Salix trees. We demonstrate cryptic isolation and reduced hybrid fitness via controlled matings of these host forms. These findings reveal host-associated postmating isolation, although a nonecological, 'intrinsic' basis for these patterns cannot be ruled out. Host preference and performance results among cross types further suggest sex-linked maternal effects on these traits, whereas family effects indicate their genetic basis and associated variation. Genes of major effect appear to influence these traits. Together with previous findings of premating isolation and adaptive differentiation in sympatry, our results meet many assumptions of 'speciation with gene flow' models. Here, such gene flow is likely asymmetric, with consequences for the dynamics of future ecological divergence and potential ecological speciation of these host forms.

  10. The Evolution and Genetics of Virus Host Shifts

    PubMed Central

    Longdon, Ben; Brockhurst, Michael A.; Russell, Colin A.; Welch, John J.; Jiggins, Francis M.

    2014-01-01

    Emerging viral diseases are often the product of a host shift, where a pathogen jumps from its original host into a novel species. Phylogenetic studies show that host shifts are a frequent event in the evolution of most pathogens, but why pathogens successfully jump between some host species but not others is only just becoming clear. The susceptibility of potential new hosts can vary enormously, with close relatives of the natural host typically being the most susceptible. Often, pathogens must adapt to successfully infect a novel host, for example by evolving to use different cell surface receptors, to escape the immune response, or to ensure they are transmitted by the new host. In viruses there are often limited molecular solutions to achieve this, and the same sequence changes are often seen each time a virus infects a particular host. These changes may come at a cost to other aspects of the pathogen's fitness, and this may sometimes prevent host shifts from occurring. Here we examine how these evolutionary factors affect patterns of host shifts and disease emergence. PMID:25375777

  11. The influence of host genetics on Marek's disease virus evolution.

    PubMed

    Hunt, Henry D; Dunn, John R

    2013-06-01

    Since the first report of a polyneuritis in chickens by Joseph Marek in 1907, the clinical nature of the disease has changed. Over the last five decades, the pathogenicity of the Marek's disease virus (MDV) has continued to evolve from the relatively mild strains observed in the 1960s to the more severe strains labeled very virulent plus currently observed in today's outbreaks. To understand the influence of host genetics, specifically the major histocompatibility complex (MHC), on virus evolution, a bacterial artificial chromosome-derived MDV (Md5B40BAC) was passed in vivo through resistant (MHC-B21) and susceptible (MHC-B13) Line 0 chickens. Criteria for selecting virus isolates for in vivo passage were based on virus replication in white blood cells 21 days after challenge and evaluation of MD pathology at necropsy. In the MHC-B13-susceptible line the Md5B40BAC virulence consistently increased from 18% Marek's disease (MD) after in vivo passage 1 (B13-IVP1 Md5B40BAC) to 94% MD after B13-IVP5 Md5B40BAC challenge. In the MHC-B21-resistant line MD virulence fluctuated from 28% at B21-IVP1 Md5B40BAC to a high of 65% in B21-IVP2 Md5B40BAC back to a low of 23% in B21-IVP5 Md5B40BAC-challenged chicks. Although the B21-IVP5 Md5B40BAC isolates were relatively mild in the MHC-B21 chicken line (56% MDV), they were highly virulent in the MHC-B13 line (100% MDV). From this series of experiments it would appear that MDV evolution toward greater virulence occurs in both susceptible and resistant MHC haplotypes, but the resulting increase in pathogenicity is constrained by the resistant MHC haplotype.

  12. Host behaviour drives parasite genetics at multiple geographic scales: population genetics of the chewing louse, Thomomydoecus minor.

    PubMed

    Harper, Sheree E; Spradling, Theresa A; Demastes, James W; Calhoun, Courtney S

    2015-08-01

    Pocket gophers and their symbiotic chewing lice form a host-parasite assemblage known for a high degree of cophylogeny, thought to be driven by life history parameters of both host and parasite that make host switching difficult. However, little work to date has focused on determining whether these life histories actually impact louse populations at the very fine scale of louse infrapopulations (individuals on a single host) at the same or at nearby host localities. We used microsatellite and mtDNA sequence data to make comparisons of chewing-louse (Thomomydoecus minor) population subdivision over time and over geographic space where there are different potential amounts of host interaction surrounding a zone of contact between two hybridizing pocket-gopher subspecies. We found that chewing lice had high levels of population isolation consistent with a paucity of horizontal transmission even at the very fine geographic scale of a single alfalfa field. We also found marked genetic discontinuity in louse populations corresponding with host subspecies and little, if any, admixture in the louse genetic groups even though the lice are closely related. The correlation of louse infrapopulation differentiation with host interaction at multiple scales, including across a discontinuity in pocket-gopher habitat, suggests that host behaviour is the primary driver of parasite genetics. This observation makes sense in light of the life histories of both chewing lice and pocket gophers and provides a powerful explanation for the well-documented pattern of parallel cladogenesis in pocket gophers and chewing lice.

  13. Analysis of host genetic diversity and viral entry as sources of between-host variation in viral load

    USGS Publications Warehouse

    Wargo, Andrew R.; Kell, Alison M.; Scott, Robert J.; Thorgaard, Gary H.; Kurath, Gael

    2012-01-01

    Little is known about the factors that drive the high levels of between-host variation in pathogen burden that are frequently observed in viral infections. Here, two factors thought to impact viral load variability, host genetic diversity and stochastic processes linked with viral entry into the host, were examined. This work was conducted with the aquatic vertebrate virus, Infectious hematopoietic necrosis virus (IHNV), in its natural host, rainbow trout. It was found that in controlled in vivo infections of IHNV, a suggestive trend of reduced between-fish viral load variation was observed in a clonal population of isogenic trout compared to a genetically diverse population of out-bred trout. However, this trend was not statistically significant for any of the four viral genotypes examined, and high levels of fish-to-fish variation persisted even in the isogenic trout population. A decrease in fish-to-fish viral load variation was also observed in virus injection challenges that bypassed the host entry step, compared to fish exposed to the virus through the natural water-borne immersion route of infection. This trend was significant for three of the four virus genotypes examined and suggests host entry may play a role in viral load variability. However, high levels of viral load variation also remained in the injection challenges. Together, these results indicate that although host genetic diversity and viral entry may play some role in between-fish viral load variation, they are not major factors. Other biological and non-biological parameters that may influence viral load variation are discussed.

  14. Modelling the evolution of common cuckoo host-races: speciation or genetic swamping?

    PubMed

    Krüger, O; Kolss, M

    2013-11-01

    Co-evolutionary arms races have provided clear evidence for evolutionary change, especially in host-parasite systems. The evolution of host-specific races in the common cuckoo (Cuculus canorus), however, is also an example where sexual conflict influences the outcome. Cuckoo females benefit from better adaptation to overcome host defences, whereas cuckoo males face a trade-off between the benefits of better adaptation to a host and the benefits of multiple mating with females from other host-races. The outcome of this trade-off might be genetic differentiation or prevention of it by genetic swamping. We use a simulation model to test which outcome is more likely with three sympatric cuckoo host-races. We assume a cost for cuckoo chicks that express a host adaptation allele not suited to their foster host species and that cuckoo males that switch to another host-race experience either a fitness benefit or cost. Over most of the parameter space, cuckoo male host-race fidelity increases significantly with time, and gene flow between host-races ceases within a few thousand to a hundred thousand generations. Our results hence support the idea that common cuckoo host-races might be in the incipient stages of speciation.

  15. Ecological and genetic aspects of grape phylloxera Daktulosphaira vitifoliae (Hemiptera: Phylloxeridae) performance on rootstock hosts.

    PubMed

    Forneck, A; Walker, M A; Blaich, R

    2001-12-01

    Performance and genetic variability of clonal lineages derived from one Californian and one German population of grape phylloxera, Daktulosphaira vitifoliae Fitch were studied on their natal grape rootstock host and on three novel hosts over four generations in an aseptic dual culture system. The ability of D. vitifoliae to adapt to new hosts was measured by changes in fitness (rm) over four generations. The performance of a given clonal lineage changed over successive generations, depending upon the host plant and the phylloxera group. Analysis of amplified fragment length polymorphism-polymerase chain reaction (AFLP-PCR) banding patterns from 40 individual parthenogenetic D. vitifoliae revealed equal levels of genetic variation both among the four clonal lineages analysed and within the different generations of one lineage. Analysis of molecular variance (AMOVA) showed no significant differences between the D. vitifoliae lineages reared on different host plants, nor was a correlation between host performance and genotype found.

  16. Host Genetic Control of the Microbiota Mediates the Drosophila Nutritional Phenotype

    PubMed Central

    Chaston, John M.; Dobson, Adam J.; Newell, Peter D.

    2015-01-01

    A wealth of studies has demonstrated that resident microorganisms (microbiota) influence the pattern of nutrient allocation to animal protein and energy stores, but it is unclear how the effects of the microbiota interact with other determinants of animal nutrition, including animal genetic factors and diet. Here, we demonstrate that members of the gut microbiota in Drosophila melanogaster mediate the effect of certain animal genetic determinants on an important nutritional trait, triglyceride (lipid) content. Parallel analysis of the taxonomic composition of the associated bacterial community and host nutritional indices (glucose, glycogen, triglyceride, and protein contents) in multiple Drosophila genotypes revealed significant associations between the abundance of certain microbial taxa, especially Acetobacteraceae and Xanthamonadaceae, and host nutritional phenotype. By a genome-wide association study of Drosophila lines colonized with a defined microbiota, multiple host genes were statistically associated with the abundance of one bacterium, Acetobacter tropicalis. Experiments using mutant Drosophila validated the genetic association evidence and reveal that host genetic control of microbiota abundance affects the nutritional status of the flies. These data indicate that the abundance of the resident microbiota is influenced by host genotype, with consequent effects on nutrient allocation patterns, demonstrating that host genetic control of the microbiome contributes to the genotype-phenotype relationship of the animal host. PMID:26567306

  17. Genetic Drift, Purifying Selection and Vector Genotype Shape Dengue Virus Intra-host Genetic Diversity in Mosquitoes.

    PubMed

    Lequime, Sebastian; Fontaine, Albin; Ar Gouilh, Meriadeg; Moltini-Conclois, Isabelle; Lambrechts, Louis

    2016-06-01

    Due to their error-prone replication, RNA viruses typically exist as a diverse population of closely related genomes, which is considered critical for their fitness and adaptive potential. Intra-host demographic fluctuations that stochastically reduce the effective size of viral populations are a challenge to maintaining genetic diversity during systemic host infection. Arthropod-borne viruses (arboviruses) traverse several anatomical barriers during infection of their arthropod vectors that are believed to impose population bottlenecks. These anatomical barriers have been associated with both maintenance of arboviral genetic diversity and alteration of the variant repertoire. Whether these patterns result from stochastic sampling (genetic drift) rather than natural selection, and/or from the influence of vector genetic heterogeneity has not been elucidated. Here, we used deep sequencing of full-length viral genomes to monitor the intra-host evolution of a wild-type dengue virus isolate during infection of several mosquito genetic backgrounds. We estimated a bottleneck size ranging from 5 to 42 founding viral genomes at initial midgut infection, irrespective of mosquito genotype, resulting in stochastic reshuffling of the variant repertoire. The observed level of genetic diversity increased following initial midgut infection but significantly differed between mosquito genetic backgrounds despite a similar initial bottleneck size. Natural selection was predominantly negative (purifying) during viral population expansion. Taken together, our results indicate that dengue virus intra-host genetic diversity in the mosquito vector is shaped by genetic drift and purifying selection, and point to a novel role for vector genetic factors in the genetic breadth of virus populations during infection. Identifying the evolutionary forces acting on arboviral populations within their arthropod vector provides novel insights into arbovirus evolution.

  18. Genetic Drift, Purifying Selection and Vector Genotype Shape Dengue Virus Intra-host Genetic Diversity in Mosquitoes

    PubMed Central

    Fontaine, Albin; Ar Gouilh, Meriadeg; Moltini-Conclois, Isabelle

    2016-01-01

    Due to their error-prone replication, RNA viruses typically exist as a diverse population of closely related genomes, which is considered critical for their fitness and adaptive potential. Intra-host demographic fluctuations that stochastically reduce the effective size of viral populations are a challenge to maintaining genetic diversity during systemic host infection. Arthropod-borne viruses (arboviruses) traverse several anatomical barriers during infection of their arthropod vectors that are believed to impose population bottlenecks. These anatomical barriers have been associated with both maintenance of arboviral genetic diversity and alteration of the variant repertoire. Whether these patterns result from stochastic sampling (genetic drift) rather than natural selection, and/or from the influence of vector genetic heterogeneity has not been elucidated. Here, we used deep sequencing of full-length viral genomes to monitor the intra-host evolution of a wild-type dengue virus isolate during infection of several mosquito genetic backgrounds. We estimated a bottleneck size ranging from 5 to 42 founding viral genomes at initial midgut infection, irrespective of mosquito genotype, resulting in stochastic reshuffling of the variant repertoire. The observed level of genetic diversity increased following initial midgut infection but significantly differed between mosquito genetic backgrounds despite a similar initial bottleneck size. Natural selection was predominantly negative (purifying) during viral population expansion. Taken together, our results indicate that dengue virus intra-host genetic diversity in the mosquito vector is shaped by genetic drift and purifying selection, and point to a novel role for vector genetic factors in the genetic breadth of virus populations during infection. Identifying the evolutionary forces acting on arboviral populations within their arthropod vector provides novel insights into arbovirus evolution. PMID:27304978

  19. Delicious poison: genetics of Drosophila host plant preference.

    PubMed

    Whiteman, Noah K; Pierce, Naomi E

    2008-09-01

    Insects use chemical cues to identify host plants, which suggests that chemosensory perception could be a target of natural selection during host specialization. Five papers using data from the 12 recently sequenced Drosophila genomes examined chemosensory gene function and evolution across specialist and generalist species. A functional study identifies odorant binding proteins that mediate loss of toxin avoidance in a specialist, and targeted genomic studies indicate specialists and island endemics lose chemosensory genes more rapidly than generalist and mainland relatives. Together, these studies suggest a mode of chemoreceptor evolution dominated by birth/death dynamics, coupled with a low level of potential positive selection.

  20. Comparative host-parasite population genetic structures: obligate fly ectoparasites on Galapagos seabirds.

    PubMed

    Levin, Iris I; Parker, Patricia G

    2013-08-01

    Parasites often have shorter generation times and, in some cases, faster mutation rates than their hosts, which can lead to greater population differentiation in the parasite relative to the host. Here we present a population genetic study of two ectoparasitic flies, Olfersia spinifera and Olfersia aenescens compared with their respective bird hosts, great frigatebirds (Fregata minor) and Nazca boobies (Sula granti). Olfersia spinifera is the vector of a haemosporidian parasite, Haemoproteus iwa, which infects frigatebirds throughout their range. Interestingly, there is no genetic differentiation in the haemosporidian parasite across this range despite strong genetic differentiation between Galapagos frigatebirds and their non-Galapagos conspecifics. It is possible that the broad distribution of this one H. iwa lineage could be facilitated by movement of infected O. spinifera. Therefore, we predicted more gene flow in both fly species compared with the bird hosts. Mitochondrial DNA sequence data from three genes per species indicated that despite marked differences in the genetic structure of the bird hosts, gene flow was very high in both fly species. A likely explanation involves non-breeding movements of hosts, including movement of juveniles, and movement by adult birds whose breeding attempt has failed, although we cannot rule out the possibility that closely related host species may be involved.

  1. Influence of early life exposure, host genetics and diet on the mouse gut microbiome and metabolome.

    PubMed

    Snijders, Antoine M; Langley, Sasha A; Kim, Young-Mo; Brislawn, Colin J; Noecker, Cecilia; Zink, Erika M; Fansler, Sarah J; Casey, Cameron P; Miller, Darla R; Huang, Yurong; Karpen, Gary H; Celniker, Susan E; Brown, James B; Borenstein, Elhanan; Jansson, Janet K; Metz, Thomas O; Mao, Jian-Hua

    2016-11-28

    Although the gut microbiome plays important roles in host physiology, health and disease(1), we lack understanding of the complex interplay between host genetics and early life environment on the microbial and metabolic composition of the gut. We used the genetically diverse Collaborative Cross mouse system(2) to discover that early life history impacts the microbiome composition, whereas dietary changes have only a moderate effect. By contrast, the gut metabolome was shaped mostly by diet, with specific non-dietary metabolites explained by microbial metabolism. Quantitative trait analysis identified mouse genetic trait loci (QTL) that impact the abundances of specific microbes. Human orthologues of genes in the mouse QTL are implicated in gastrointestinal cancer. Additionally, genes located in mouse QTL for Lactobacillales abundance are implicated in arthritis, rheumatic disease and diabetes. Furthermore, Lactobacillales abundance was predictive of higher host T-helper cell counts, suggesting an important link between Lactobacillales and host adaptive immunity.

  2. Influence of early life exposure, host genetics and diet on the mouse gut microbiome and metabolome

    SciTech Connect

    Snijders, Antoine M.; Langley, Sasha A.; Kim, Young-Mo; Brislawn, Colin J.; Noecker, Cecilia; Zink, Erika M.; Fansler, Sarah J.; Casey, Cameron P.; Miller, Darla R.; Huang, Yurong; Karpen, Gary H.; Celniker, Susan E.; Brown, James B.; Borenstein, Elhanan; Jansson, Janet K.; Metz, Thomas O.; Mao, Jian-Hua

    2016-11-28

    Although the gut microbiome plays important roles in host physiology, health and disease1, we lack understanding of the complex interplay between host genetics and early life environment on the microbial and metabolic composition of the gut.We used the genetically diverse Collaborative Cross mouse system2 to discover that early life history impacts themicrobiome composition, whereas dietary changes have only a moderate effect. By contrast, the gut metabolome was shaped mostly by diet, with specific non-dietary metabolites explained by microbial metabolism. Quantitative trait analysis identified mouse genetic trait loci (QTL) that impact the abundances of specific microbes. Human orthologues of genes in the mouse QTL are implicated in gastrointestinal cancer. Additionally, genes located in mouse QTL for Lactobacillales abundance are implicated in arthritis, rheumatic disease and diabetes. Furthermore, Lactobacillales abundance was predictive of higher host T-helper cell counts, suggesting an important link between Lactobacillales and host adaptive immunity.

  3. Host genetics is associated with the gut microbial community membership rather than the structure.

    PubMed

    Zhao, Peihua; Irwin, David M; Dong, Dong

    2016-04-26

    The issue of what factors shape the gut microbiota has been studied for years. However, questions on the contribution of host genetics to the colonizing process of the gut microbiota and to the extent that host genetics affect the gut microbiota have not yet been clearly answered. Most recently published reports have concluded that host genetics make a smaller contribution than other factors, such as diet, in determining the gut microbiota. Here we have exploited the increasing amount of fecal 16S rRNA gene sequencing data that are becoming available to conduct an analysis to assess the influence of host genetics on the diversity of the gut microbiota. By re-analyzing data obtained from over 5000 stool samples, representing individuals living on five continents and ranging in age from 3 days to 87 years, we found that the strength of the various factors affecting the membership or structure of the gut microbiota are quite different, which leads us to a hypothesis that the presence or absence of taxa is largely controlled by host genetics, whereas non-genetic factors regulate the abundance of each taxon. This hypothesis is supported by the finding that the genome similarity positively correlates with the similarity of community membership. Finally, we showed that only severe perturbations are able to alter the gut microbial community membership. In summary, our work provides new insights into understanding the complexities of the gut microbial community and how it responds to changes imposed on it.

  4. Relocation, high-latitude warming and host genetic identity shape the foliar fungal microbiome of poplars.

    PubMed

    Bálint, Miklós; Bartha, László; O'Hara, Robert B; Olson, Matthew S; Otte, Jürgen; Pfenninger, Markus; Robertson, Amanda L; Tiffin, Peter; Schmitt, Imke

    2015-01-01

    Micro-organisms associated with plants and animals affect host fitness, shape community structure and influence ecosystem properties. Climate change is expected to influence microbial communities, but their reactions are not well understood. Host-associated micro-organisms are influenced by the climate reactions of their hosts, which may undergo range shifts due to climatic niche tracking, or may be actively relocated to mitigate the effects of climate change. We used a common-garden experiment and rDNA metabarcoding to examine the effect of host relocation and high-latitude warming on the complex fungal endophytic microbiome associated with leaves of an ecologically dominant boreal forest tree (Populus balsamifera L.). We also considered the potential effects of poplar genetic identity in defining the reactions of the microbiome to the treatments. The relocation of hosts to the north increased the diversity of the microbiome and influenced its structure, with results indicating enemy release from plausible pathogens. High-latitude warming decreased microbiome diversity in comparison with natural northern conditions. The warming also caused structural changes, which made the fungal communities distinct in comparison with both low-latitude and high-latitude natural communities, and increased the abundance of plausible pathogens. The reactions of the microbiome to relocation and warming were strongly dependent on host genetic identity. This suggests that climate change effects on host-microbiome systems may be mediated by the interaction of environmental factors and the population genetic processes of the hosts.

  5. Host association drives genetic divergence in the bed bug, Cimex lectularius.

    PubMed

    Booth, Warren; Balvín, Ondřej; Vargo, Edward L; Vilímová, Jitka; Schal, Coby

    2015-03-01

    Genetic differentiation may exist among sympatric populations of a species due to long-term associations with alternative hosts (i.e. host-associated differentiation). While host-associated differentiation has been documented in several phytophagus insects, there are far fewer cases known in animal parasites. The bed bug, Cimex lectularius, a wingless insect, represents a potential model organism for elucidating the processes involved in host-associated differentiation in animal parasites with relatively limited mobility. In conjunction with the expansion of modern humans from Africa into Eurasia, it has been speculated that bed bugs extended their host range from bats to humans in their shared cave domiciles throughout Eurasia. C. lectularius that associate with humans have a cosmopolitan distribution, whereas those associated with bats occur across Europe, often in human-built structures. We assessed genetic structure and gene flow within and among populations collected in association with each host using mtDNA, microsatellite loci and knock-down resistance gene variants. Both nuclear and mitochondrial data support a lack of significant contemporary gene flow between host-specific populations. Within locations human-associated bed bug populations exhibit limited genetic diversity and elevated levels of inbreeding, likely due to human-mediated movement, infrequent additional introduction events per infestation, and pest control. In contrast, populations within bat roosts exhibit higher genetic diversity and lower levels of relatedness, suggesting populations are stable with temporal fluctuations due to host dispersal and bug mortality. In concert with previously published evidence of morphological and behavioural differentiation, the genetic data presented here suggest C. lectularius is currently undergoing lineage divergence through host association.

  6. The host acts as a genetic bottleneck during serial infections: an insect-fungal model system.

    PubMed

    Scully, Lisa R; Bidochka, Michael J

    2006-11-01

    The genetic variation of a pathogen population is a pivotal component of pathogen evolution, having important implications for emerging diseases, nosocomial infections, and laboratory subculturing practices. Furthermore, it is undoubtedly altered during infection of a host. We address this issue using an insect-fungal model system to examine the influence of serial host passage on the genetic variation of a pathogen population. Using amplified fragment length polymorphism, a strain of the opportunistic fungus, Aspergillus flavus, showing initially 98% genetic similarity, was assessed for changes in genetic diversity during repeated passage through Galleria mellonella larvae and compared to that of a parallel population serially subcultured on artificial media. In two independent trials, the genetic diversity of the population passed through the insect dropped significantly, while the genetic variation of the population subcultured on media increased or remained unchanged. However, there were no changes in virulence or the production of protease or aflatoxin, indicating an apparent lack of selection. We suggest that the insect acted as a genetic bottleneck, reducing the genetic diversity of the A. flavus population. The ability of a host to produce a genetic bottleneck in a pathogen population impacts our understanding of emerging diseases, nosocomial infections, and laboratory subculturing practices.

  7. The relative importance of host-plant genetic diversity in structuring the associated herbivore community.

    PubMed

    Tack, Ayco J M; Roslin, Tomas

    2011-08-01

    Recent studies suggest that intraspecific genetic diversity in one species may leave a substantial imprint on the surrounding community and ecosystem. Here, we test the hypothesis that genetic diversity within host-plant patches translates into consistent and ecologically important changes in the associated herbivore community. More specifically, we use potted, grafted oak saplings to construct 41 patches of four saplings each, with one, two, or four tree genotypes represented among the host plants. These patches were divided among two common gardens. Focusing first at the level of individual trees, we assess how tree-specific genotypic identity, patch-level genetic diversity, garden-level environmental variation, and their interactions affect the structure of the herbivore community. At the level of host-plant patches, we analyze whether the joint responses of herbivore species to environmental variation and genetic diversity result in differences in species diversity among tree quartets. Strikingly, both species-specific abundances and species diversity varied substantially among host-tree genotypes, among common gardens, and among specific locations within individual gardens. In contrast, the genetic diversity of the patch left a detectable imprint on local abundances of only two herbivore taxa. In both cases, the effect of genetic diversity was inconsistent among gardens and among host-plant genotypes. While the insect community differed significantly among individual host-plant genotypes, there were no interactive effects of the number of different genotypes within the patch. Overall, additive effects of intraspecific genetic diversity of the host plant explained a similar or lower proportion (7-10%) of variation in herbivore species diversity than did variation among common gardens. Combined with the few previous studies published to date, our study suggests that the impact of host-plant genetic diversity on the herbivore community can range from none to

  8. Inbreeding within human Schistosoma mansoni: do host-specific factors shape the genetic composition of parasite populations?

    PubMed

    Van den Broeck, F; Meurs, L; Raeymaekers, J A M; Boon, N; Dieye, T N; Volckaert, F A M; Polman, K; Huyse, T

    2014-07-01

    The size, structure and distribution of host populations are key determinants of the genetic composition of parasite populations. Despite the evolutionary and epidemiological merits, there has been little consideration of how host heterogeneities affect the evolutionary trajectories of parasite populations. We assessed the genetic composition of natural populations of the parasite Schistosoma mansoni in northern Senegal. A total of 1346 parasites were collected from 14 snail and 57 human hosts within three villages and individually genotyped using nine microsatellite markers. Human host demographic parameters (age, gender and village of residence) and co-infection with Schistosoma haematobium were documented, and S. mansoni infection intensities were quantified. F-statistics and clustering analyses revealed a random distribution (panmixia) of parasite genetic variation among villages and hosts, confirming the concept of human hosts as 'genetic mixing bowls' for schistosomes. Host gender and village of residence did not show any association with parasite genetics. Host age, however, was significantly correlated with parasite inbreeding and heterozygosity, with children being more infected by related parasites than adults. The patterns may be explained by (1) genotype-dependent 'concomitant immunity' that leads to selective recruitment of genetically unrelated worms with host age, and/or (2) the 'genetic mixing bowl' hypothesis, where older hosts have been exposed to a wider variety of parasite strains than children. The present study suggests that host-specific factors may shape the genetic composition of schistosome populations, revealing important insights into host-parasite interactions within a natural system.

  9. Geographic genetic differentiation of a malaria parasite, Plasmodium mexicanum, and its lizard host, Sceloporus occidentalis.

    PubMed

    Fricke, Jennifer M; Vardo-Zalik, Anne M; Schall, Jos J

    2010-04-01

    Gene flow, and resulting degree of genetic differentiation among populations, will shape geographic genetic patterns and possibly local adaptation of parasites and their hosts. Some studies of Plasmodium falciparum in humans show substantial differentiation of the parasite in locations separated by only a few kilometers, a paradoxical finding for a parasite in a large, mobile host. We examined genetic differentiation of the malaria parasite Plasmodium mexicanum, and its lizard host, Sceloporus occidentalis, at 8 sites in northern California, with the use of variable microsatellite markers for both species. These lizards are small and highly territorial, so we expected local genetic differentiation of both parasite and lizard. Populations of P. mexicanum were found to be differentiated by analysis of 5 markers (F(st) values >0.05-0.10) over distances as short as 230-400 m, and greatly differentiated (F(st) values >0.25) for sites separated by approximately 10 km. In contrast, the lizard host had no, or very low, levels of differentiation for 3 markers, even for sites >40 km distant. Thus, gene flow for the lizard was great, but despite the mobility of the vertebrate host, the parasite was locally genetically distinct. This discrepancy could result if infected lizards move little, but their noninfected relatives were more mobile. Previous studies on the virulence of P. mexicanum for fence lizards support this hypothesis. However, changing prevalence of the parasite, without changes in density of the lizard, could also result in this pattern.

  10. Genetic engineering alveolar macrophages for host resistance to PRRSV.

    PubMed

    Prather, Randall S; Whitworth, Kristin M; Schommer, Susan K; Wells, Kevin D

    2017-02-10

    Standard strategies for control of porcine reproductive and respiratory syndrome virus (PRRSV) have not been effective, as vaccines have not reduced the prevalence of disease and many producers depopulate after an outbreak. Another method of control would be to prevent the virus from infecting the pig. The virus was thought to infect alveolar macrophages by interaction with a variety of cell surface molecules. One popular model had PRRSV first interacting with heparin sulfate followed by binding to sialoadhesin and then being internalized into an endosome. Within the endosome, PRRSV was thought to interact with CD163 to uncoat the virus so the viral genome could be released into the cytosol and infect the cell. Other candidate receptors have included vimentin, CD151 and CD209. By using genetic engineering, it is possible to test the importance of individual entry mediators by knocking them out. Pigs engineered by knockout of sialoadhesin were still susceptible to infection, while CD163 knockout resulted in pigs that were resistant to infection. Genetic engineering is not only a valuable tool to determine the role of specific proteins in infection by PRRSV (in this case), but also provides a means to create animals resistant to disease. Genetic engineering of alveolar macrophages can also illuminate the role of other proteins in response to infection. We suggest that strategies to prevent infection be pursued to reduce the reservoir of virus.

  11. Rapid turnover of intra-host genetic diversity in Zucchini yellow mosaic virus.

    PubMed

    Simmons, Heather E; Holmes, Edward C; Stephenson, Andrew G

    2011-02-01

    Genetic diversity in RNA viruses is shaped by a variety of evolutionary processes, including the bottlenecks that may occur at inter-host transmission. However, how these processes structure genetic variation at the scale of individual hosts is only partly understood. We obtained intra-host sequence data for the coat protein (CP) gene of Zucchini yellow mosaic virus (ZYMV) from two horizontally transmitted populations - one via aphid, the other without - and with multiple samples from individual plants. We show that although mutations are generated relatively frequently within infected plants, attaining similar levels of genetic diversity to that seen in some animal RNA viruses (mean intra-sample diversity of 0.02%), most mutations are likely to be transient, deleterious, and purged rapidly. We also observed more population structure in the aphid transmitted viral population, including the same mutations in multiple clones, the presence of a sub-lineage, and evidence for the short-term complementation of defective genomes.

  12. Disturbance induced decoupling between host genetics and composition of the associated microbiome

    PubMed Central

    2013-01-01

    Background Studies of oyster microbiomes have revealed that a limited number of microbes, including pathogens, can dominate microbial communities in host tissues such as gills and gut. Much of the bacterial diversity however remains underexplored and unexplained, although environmental conditions and host genetics have been implicated. We used 454 next generation 16S rRNA amplicon sequencing of individually tagged PCR reactions to explore the diversity of bacterial communities in gill tissue of the invasive Pacific oyster Crassostrea gigas stemming from genetically differentiated beds under ambient outdoor conditions and after a multifaceted disturbance treatment imposing stress on the host. Results While the gill associated microbial communities in oysters were dominated by few abundant taxa (i.e. Sphingomonas, Mycoplasma) the distribution of rare bacterial groups correlated to relatedness between the hosts under ambient conditions. Exposing the host to disturbance broke apart this relationship by removing rare phylotypes thereby reducing overall microbial diversity. Shifts in the microbiome composition in response to stress did not result in a net increase in genera known to contain potentially pathogenic strains. Conclusion The decrease in microbial diversity and the disassociation between population genetic structure of the hosts and their associated microbiome suggest that disturbance (i.e. stress) may play a significant role for the assembly of the natural microbiome. Such community shifts may in turn also feed back on the course of disease and the occurrence of mass mortality events in oyster populations. PMID:24206899

  13. Genetic Analysis of Phytophthora nicotianae Populations from Different Hosts Using Microsatellite Markers.

    PubMed

    Biasi, Antonio; Martin, Frank N; Cacciola, Santa O; di San Lio, Gaetano Magnano; Grünwald, Niklaus J; Schena, Leonardo

    2016-09-01

    In all, 231 isolates of Phytophthora nicotianae representing 14 populations from different host genera, including agricultural crops (Citrus, Nicotiana, and Lycopersicon), potted ornamental species in nurseries (Lavandula, Convolvulus, Myrtus, Correa, and Ruta), and other plant genera were characterized using simple-sequence repeat markers. In total, 99 multilocus genotypes (MLG) were identified, revealing a strong association between genetic grouping and host of recovery, with most MLG being associated with a single host genus. Significant differences in the structure of populations were revealed but clonality prevailed in all populations. Isolates from Citrus were found to be genetically related regardless of their geographic origin and were characterized by high genetic uniformity and high inbreeding coefficients. Higher variability was observed for other populations and a significant geographical structuring was determined for isolates from Nicotiana. Detected differences were related to the propagation and cultivation systems of different crops. Isolates obtained from Citrus spp. are more likely to be distributed worldwide with infected plant material whereas Nicotiana and Lycopersicon spp. are propagated by seed, which would not contribute to the spread of the pathogen and result in a greater chance for geographic isolation of lineages. With regard to ornamental species in nurseries, the high genetic variation is likely the result of the admixture of diverse pathogen genotypes through the trade of infected plant material from various geographic origins, the presence of several hosts in the same nursery, and genetic recombination through sexual reproduction of this heterothallic species.

  14. Enhanced biofilm formation and multi-host transmission evolve from divergent genetic backgrounds in Campylobacter jejuni.

    PubMed

    Pascoe, Ben; Méric, Guillaume; Murray, Susan; Yahara, Koji; Mageiros, Leonardos; Bowen, Ryan; Jones, Nathan H; Jeeves, Rose E; Lappin-Scott, Hilary M; Asakura, Hiroshi; Sheppard, Samuel K

    2015-11-01

    Multicellular biofilms are an ancient bacterial adaptation that offers a protective environment for survival in hostile habitats. In microaerophilic organisms such as Campylobacter, biofilms play a key role in transmission to humans as the bacteria are exposed to atmospheric oxygen concentrations when leaving the reservoir host gut. Genetic determinants of biofilm formation differ between species, but little is known about how strains of the same species achieve the biofilm phenotype with different genetic backgrounds. Our approach combines genome-wide association studies with traditional microbiology techniques to investigate the genetic basis of biofilm formation in 102 Campylobacter jejuni isolates. We quantified biofilm formation among the isolates and identified hotspots of genetic variation in homologous sequences that correspond to variation in biofilm phenotypes. Thirteen genes demonstrated a statistically robust association including those involved in adhesion, motility, glycosylation, capsule production and oxidative stress. The genes associated with biofilm formation were different in the host generalist ST-21 and ST-45 clonal complexes, which are frequently isolated from multiple host species and clinical samples. This suggests the evolution of enhanced biofilm from different genetic backgrounds and a possible role in colonization of multiple hosts and transmission to humans.

  15. Genetic Dissection of the Host Tropism of Human-Tropic Pathogens

    PubMed Central

    Douam, Florian; Gaska, Jenna M.; Winer, Benjamin Y.; Ding, Qiang; von Schaewen, Markus; Ploss, Alexander

    2016-01-01

    Infectious diseases are the second leading cause of death worldwide. Although the host multitropism of some pathogens has rendered their manipulation possible in animal models, the human-restricted tropism of numerous viruses, bacteria, fungi, and parasites has seriously hampered our understanding of these pathogens. Hence, uncovering the genetic basis underlying the narrow tropism of such pathogens is critical for understanding their mechanisms of infection and pathogenesis. Moreover, such genetic dissection is essential for the generation of permissive animal models that can serve as critical tools for the development of therapeutics or vaccines against challenging human pathogens. In this review, we describe different experimental approaches utilized to uncover the genetic foundation regulating pathogen host tropism as well as their relevance for studying the tropism of several important human pathogens. Finally, we discuss the current and future uses of this knowledge for generating genetically modified animal models permissive for these pathogens. PMID:26407032

  16. Genetic Dissection of the Host Tropism of Human-Tropic Pathogens.

    PubMed

    Douam, Florian; Gaska, Jenna M; Winer, Benjamin Y; Ding, Qiang; von Schaewen, Markus; Ploss, Alexander

    2015-01-01

    Infectious diseases are the second leading cause of death worldwide. Although the host multitropism of some pathogens has rendered their manipulation possible in animal models, the human-restricted tropism of numerous viruses, bacteria, fungi, and parasites has seriously hampered our understanding of these pathogens. Hence, uncovering the genetic basis underlying the narrow tropism of such pathogens is critical for understanding their mechanisms of infection and pathogenesis. Moreover, such genetic dissection is essential for the generation of permissive animal models that can serve as critical tools for the development of therapeutics or vaccines against challenging human pathogens. In this review, we describe different experimental approaches utilized to uncover the genetic foundation regulating pathogen host tropism as well as their relevance for studying the tropism of several important human pathogens. Finally, we discuss the current and future uses of this knowledge for generating genetically modified animal models permissive for these pathogens.

  17. Genetic bottlenecks during systemic movement of Cucumber mosaic virus vary in different host plants

    SciTech Connect

    Ali, Akhtar; Roossinck, Marilyn J.

    2010-09-01

    Genetic bottlenecks are stochastic events that narrow variation in a population. We compared bottlenecks during the systemic infection of Cucumber mosaic virus (CMV) in four host plants. We mechanically inoculated an artificial population of twelve CMV mutants to young leaves of tomato, pepper, Nicotiana benthamiana, and squash. The inoculated leaves and primary and secondary systemically infected leaves were sampled at 2, 10, and 15 days post-inoculation. All twelve mutants were detected in all of the inoculated leaves. The number of mutants recovered from the systemically infected leaves of all host species was reduced significantly, indicating bottlenecks in systemic movement. The recovery frequencies of a few of the mutants were significantly different in each host probably due to host-specific selective forces. These results have implications for the differences in virus population variation that is seen in different host plants.

  18. Host genetic diversity enables Ebola hemorrhagic fever pathogenesis and resistance.

    PubMed

    Rasmussen, Angela L; Okumura, Atsushi; Ferris, Martin T; Green, Richard; Feldmann, Friederike; Kelly, Sara M; Scott, Dana P; Safronetz, David; Haddock, Elaine; LaCasse, Rachel; Thomas, Matthew J; Sova, Pavel; Carter, Victoria S; Weiss, Jeffrey M; Miller, Darla R; Shaw, Ginger D; Korth, Marcus J; Heise, Mark T; Baric, Ralph S; de Villena, Fernando Pardo-Manuel; Feldmann, Heinz; Katze, Michael G

    2014-11-21

    Existing mouse models of lethal Ebola virus infection do not reproduce hallmark symptoms of Ebola hemorrhagic fever, neither delayed blood coagulation and disseminated intravascular coagulation nor death from shock, thus restricting pathogenesis studies to nonhuman primates. Here we show that mice from the Collaborative Cross panel of recombinant inbred mice exhibit distinct disease phenotypes after mouse-adapted Ebola virus infection. Phenotypes range from complete resistance to lethal disease to severe hemorrhagic fever characterized by prolonged coagulation times and 100% mortality. Inflammatory signaling was associated with vascular permeability and endothelial activation, and resistance to lethal infection arose by induction of lymphocyte differentiation and cellular adhesion, probably mediated by the susceptibility allele Tek. These data indicate that genetic background determines susceptibility to Ebola hemorrhagic fever.

  19. Host and vector movement affects genetic diversity and spatial structure of Buggy Creek virus (Togaviridae).

    PubMed

    Brown, Charles R; Bomberger Brown, Mary; Padhi, Abinash; Foster, Jerome E; Moore, Amy T; Pfeffer, Martin; Komar, Nicholas

    2008-05-01

    Determining the degree of genetic variability and spatial structure of arthropod-borne viruses (arboviruses) may help in identifying where strains that potentially cause epidemics or epizootics occur. Genetic diversity in arboviruses is assumed to reflect relative mobility of their vertebrate hosts (and invertebrate vectors), with highly mobile hosts such as birds leading to genetic similarity of viruses over large areas. There are no empirical studies that have directly related host or vector movement to virus genetic diversity and spatial structure. Using the entire E2 glycoprotein-coding region of 377 Buggy Creek virus isolates taken from cimicid swallow bugs (Oeciacus vicarius), the principal invertebrate vector for this virus, we show that genetic diversity between sampling sites could be predicted by the extent of movement by transient cliff swallows (Petrochelidon pyrrhonota) between nesting colonies where the virus and vectors occur. Pairwise F(ST) values between colony sites declined significantly with increasing likelihood of a swallow moving between those sites per 2-day interval during the summer nesting season. Sites with more bird movement between them had virus more similar genetically than did pairs of sites with limited or no bird movement. For one virus lineage, Buggy Creek virus showed greater haplotype and nucleotide diversity at sites that had high probabilities of birds moving into or through them during the summer; these sites likely accumulated haplotypes by virtue of frequent virus introductions by birds. Cliff swallows probably move Buggy Creek virus by transporting infected bugs on their feet. The results provide the first empirical demonstration that genetic structure of an arbovirus is strongly associated with host/vector movement, and suggest caution in assuming that bird-dispersed arboviruses always have low genetic differentiation across different sites.

  20. Ecological and genetic factors influencing the transition between host-use strategies in sympatric Heliconius butterflies.

    PubMed

    Merrill, R M; Naisbit, R E; Mallet, J; Jiggins, C D

    2013-09-01

    Shifts in host-plant use by phytophagous insects have played a central role in their diversification. Evolving host-use strategies will reflect a trade-off between selection pressures. The ecological niche of herbivorous insects is partitioned along several dimensions, and if populations remain in contact, recombination will break down associations between relevant loci. As such, genetic architecture can profoundly affect the coordinated divergence of traits and subsequently the ability to exploit novel habitats. The closely related species Heliconius cydno and H. melpomene differ in mimetic colour pattern, habitat and host-plant use. We investigate the selection pressures and genetic basis underlying host-use differences in these two species. Host-plant surveys reveal that H. melpomene specializes on a single species of Passiflora. This is also true for the majority of other Heliconius species in secondary growth forest at our study site, as expected under a model of interspecific competition. In contrast, H. cydno, which uses closed-forest habitats where both Heliconius and Passiflora are less common, appears not to be restricted by competition and uses a broad selection of the available Passiflora. However, other selection pressures are likely involved, and field experiments reveal that early larval survival of both butterfly species is highest on Passiflora menispermifolia, but most markedly so for H. melpomene, the specialist on that host. Finally, we demonstrate an association between host-plant acceptance and colour pattern amongst interspecific hybrids, suggesting that major loci underlying these important ecological traits are physically linked in the genome. Together, our results reveal ecological and genetic associations between shifts in habitat, host use and mimetic colour pattern that have likely facilitated both speciation and coexistence.

  1. Ecological and Genetic Differences between Cacopsylla melanoneura (Hemiptera, Psyllidae) Populations Reveal Species Host Plant Preference

    PubMed Central

    Malagnini, Valeria; Pedrazzoli, Federico; Papetti, Chiara; Cainelli, Christian; Zasso, Rosaly; Gualandri, Valeria; Pozzebon, Alberto; Ioriatti, Claudio

    2013-01-01

    The psyllid Cacopsylla melanoneura is considered one of the vectors of ‘Candidatus Phytoplasma mali’, the causal agent of apple proliferation disease. In Northern Italy, overwintered C. melanoneura adults reach apple and hawthorn around the end of January. Nymph development takes place between March and the end of April. The new generation adults migrate onto conifers around mid-June and come back to the host plant species after overwintering. In this study we investigated behavioural differences, genetic differentiation and gene flow between samples of C. melanoneura collected from the two different host plants. Further analyses were performed on some samples collected from conifers. To assess the ecological differences, host-switching experiments were conducted on C. melanoneura samples collected from apple and hawthorn. Furthermore, the genetic structure of the samples was studied by genotyping microsatellite markers. The examined C. melanoneura samples performed better on their native host plant species. This was verified in terms of oviposition and development of the offspring. Data resulting from microsatellite analysis indicated a low, but statistically significant difference between collected-from-apple and hawthorn samples. In conclusion, both ecological and genetic results indicate a differentiation between C. melanoneura samples associated with the two host plants. PMID:23874980

  2. Genetic differentiation associated with host plants and geography among six widespread species of South American Blepharoneura fruit flies (Tephritidae).

    PubMed

    Ottens, K; Winkler, I S; Lewis, M L; Scheffer, S J; Gomes-Costa, G A; Condon, M A; Forbes, A A

    2017-04-01

    Tropical herbivorous insects are astonishingly diverse, and many are highly host-specific. Much evidence suggests that herbivorous insect diversity is a function of host plant diversity; yet, the diversity of some lineages exceeds the diversity of plants. Although most species of herbivorous fruit flies in the Neotropical genus Blepharoneura are strongly host-specific (they deposit their eggs in a single host plant species and flower sex), some species are collected from multiple hosts or flowers and these may represent examples of lineages that are diversifying via changes in host use. Here, we investigate patterns of diversification within six geographically widespread Blepharoneura species that have been collected and reared from at least two host plant species or host plant parts. We use microsatellites to (1) test for evidence of local genetic differentiation associated with different sympatric hosts (different plant species or flower sexes) and (2) examine geographic patterns of genetic differentiation across multiple South American collection sites. In four of the six fly species, we find evidence of local genetic differences between flies collected from different hosts. All six species show evidence of geographic structure, with consistent differences between flies collected in the Guiana Shield and flies collected in Amazonia. Continent-wide analyses reveal - in all but one instance - that genetically differentiated flies collected in sympatry from different host species or different sex flowers are not one another's closest relatives, indicating that genetic differences often arise in allopatry before, or at least coincident with, the evolution of novel host use.

  3. Analysis of the association between host genetics, smoking, and sputum microbiota in healthy humans

    PubMed Central

    Lim, Mi Young; Yoon, Hyo Shin; Rho, Mina; Sung, Joohon; Song, Yun-Mi; Lee, Kayoung; Ko, GwangPyo

    2016-01-01

    Recent studies showing clear differences in the airway microbiota between healthy and diseased individuals shed light on the importance of the airway microbiota in health. Here, we report the associations of host genetics and lifestyles such as smoking, alcohol consumption, and physical activity with the composition of the sputum microbiota using 16S rRNA gene sequence data generated from 257 sputum samples of Korean twin-family cohort. By estimating the heritability of each microbial taxon, we found that several taxa, including Providencia and Bacteroides, were significantly influenced by host genetic factors. Smoking had the strongest effect on the overall microbial community structure among the tested lifestyle factors. The abundances of Veillonella and Megasphaera were higher in current-smokers, and increased with the pack-year value and the Fagerstrom Test of Nicotine Dependence (FTND) score. In contrast, Haemophilus decreased with the pack-year of smoking and the FTND score. Co-occurrence network analysis showed that the taxa were clustered according to the direction of associations with smoking, and that the taxa influenced by host genetics were found together. These results demonstrate that the relationships among sputum microbial taxa are closely associated with not only smoking but also host genetics. PMID:27030383

  4. Mutualism effectiveness and vertical transmission of symbiotic fungal endophytes in response to host genetic background.

    PubMed

    Gundel, Pedro E; Martínez-Ghersa, María A; Omacini, Marina; Cuyeu, Romina; Pagano, Elba; Ríos, Raúl; Ghersa, Claudio M

    2012-12-01

    Certain species of the Pooideae subfamily develop stress tolerance and herbivory resistance through symbiosis with vertically transmitted, asexual fungi. This symbiosis is specific, and genetic factors modulate the compatibility between partners. Although gene flow is clearly a fitness trait in allogamous grasses, because it injects hybrid vigor and raw material for evolution, it could reduce compatibility and thus mutualism effectiveness. To explore the importance of host genetic background in modulating the performance of symbiosis, Lolium multiflorum plants, infected and noninfected with Neotyphodium occultans, were crossed with genetically distant plants of isolines (susceptible and resistant to diclofop-methyl herbicide) bred from two cultivars and exposed to stress. The endophyte improved seedling survival in genotypes susceptible to herbicide, while it had a negative effect on one of the genetically resistant crosses. Mutualism provided resistance to herbivory independently of the host genotype, but this effect vanished under stress. While no endophyte effect was observed on host reproductive success, it was increased by interpopulation plant crosses. Neither gene flow nor herbicide had an important impact on endophyte transmission. Host fitness improvements attributable to gene flow do not appear to result in direct conflict with mutualism while this seems to be an important mechanism for the ecological and contemporary evolution of the symbiotum.

  5. Mutualism effectiveness and vertical transmission of symbiotic fungal endophytes in response to host genetic background

    PubMed Central

    Gundel, Pedro E; Martínez-Ghersa, María A; Omacini, Marina; Cuyeu, Romina; Pagano, Elba; Ríos, Raúl; Ghersa, Claudio M

    2012-01-01

    Certain species of the Pooideae subfamily develop stress tolerance and herbivory resistance through symbiosis with vertically transmitted, asexual fungi. This symbiosis is specific, and genetic factors modulate the compatibility between partners. Although gene flow is clearly a fitness trait in allogamous grasses, because it injects hybrid vigor and raw material for evolution, it could reduce compatibility and thus mutualism effectiveness. To explore the importance of host genetic background in modulating the performance of symbiosis, Lolium multiflorum plants, infected and noninfected with Neotyphodium occultans, were crossed with genetically distant plants of isolines (susceptible and resistant to diclofop-methyl herbicide) bred from two cultivars and exposed to stress. The endophyte improved seedling survival in genotypes susceptible to herbicide, while it had a negative effect on one of the genetically resistant crosses. Mutualism provided resistance to herbivory independently of the host genotype, but this effect vanished under stress. While no endophyte effect was observed on host reproductive success, it was increased by interpopulation plant crosses. Neither gene flow nor herbicide had an important impact on endophyte transmission. Host fitness improvements attributable to gene flow do not appear to result in direct conflict with mutualism while this seems to be an important mechanism for the ecological and contemporary evolution of the symbiotum. PMID:23346228

  6. Analysis of the association between host genetics, smoking, and sputum microbiota in healthy humans.

    PubMed

    Lim, Mi Young; Yoon, Hyo Shin; Rho, Mina; Sung, Joohon; Song, Yun-Mi; Lee, Kayoung; Ko, GwangPyo

    2016-03-31

    Recent studies showing clear differences in the airway microbiota between healthy and diseased individuals shed light on the importance of the airway microbiota in health. Here, we report the associations of host genetics and lifestyles such as smoking, alcohol consumption, and physical activity with the composition of the sputum microbiota using 16S rRNA gene sequence data generated from 257 sputum samples of Korean twin-family cohort. By estimating the heritability of each microbial taxon, we found that several taxa, including Providencia and Bacteroides, were significantly influenced by host genetic factors. Smoking had the strongest effect on the overall microbial community structure among the tested lifestyle factors. The abundances of Veillonella and Megasphaera were higher in current-smokers, and increased with the pack-year value and the Fagerstrom Test of Nicotine Dependence (FTND) score. In contrast, Haemophilus decreased with the pack-year of smoking and the FTND score. Co-occurrence network analysis showed that the taxa were clustered according to the direction of associations with smoking, and that the taxa influenced by host genetics were found together. These results demonstrate that the relationships among sputum microbial taxa are closely associated with not only smoking but also host genetics.

  7. Host-parasite genetic interactions and virulence-transmission relationships in natural populations of monarch butterflies.

    PubMed

    de Roode, Jacobus C; Altizer, Sonia

    2010-02-01

    Evolutionary models predict that parasite virulence (parasite-induced host mortality) can evolve as a consequence of natural selection operating on between-host parasite transmission. Two major assumptions are that virulence and transmission are genetically related and that the relative virulence and transmission of parasite genotypes remain similar across host genotypes. We conducted a cross-infection experiment using monarch butterflies and their protozoan parasites from two populations in eastern and western North America. We tested each of 10 host family lines against each of 18 parasite genotypes and measured virulence (host life span) and parasite transmission potential (spore load). Consistent with virulence evolution theory, we found a positive relationship between virulence and transmission across parasite genotypes. However, the absolute values of virulence and transmission differed among host family lines, as did the rank order of parasite clones along the virulence-transmission relationship. Population-level analyses showed that parasites from western North America caused higher infection levels and virulence, but there was no evidence of local adaptation of parasites on sympatric hosts. Collectively, our results suggest that host genotypes can affect the strength and direction of selection on virulence in natural populations, and that predicting virulence evolution may require building genotype-specific interactions into simpler trade-off models.

  8. Genetic differentiation among Maconellicoccus hirsutus (Hemiptera: Pseudococcidae) populations living on different host plants.

    PubMed

    Rosas-García, Ninfa M; Sarmiento-Benavides, Sandra L; Villegas-Mendoza, Jesús M; Hernández-Delgado, Sanjuana; Mayek-Pérez, Netzahualcoyotl

    2010-06-01

    The pink hibiscus mealybug Maconellicoccus hirsutus (Green) is a dangerous pest that damages a wide variety of agricultural, horticultural, and forestry crops. Amplified fragment length polymorphism (AFLP) fingerprints were used to characterize the genetic variation of 11 M. hirsutus populations infesting three plant species in Nayarit, Mexico. Analysis was carried out using four primers combinations, producing 590 polymorphic bands. Cluster analysis, as well as bootstrap dendrogram and nonmetric multidimensional scaling analysis, grouped M. hirsutus populations according to their host plant. The estimated F(ST) values indicated a high differentiation in M. hirsutus populations among the three host plant species. These results were also supported by a Bayesian analysis, which indicated a population clustering robustness according to their host plant. Genetic variation among populations is not caused by geographic distances, as shown by a Mantel test.

  9. Genetic Factors and Host Traits Predict Spore Morphology for a Butterfly Pathogen

    PubMed Central

    Sander, Sarah E.; Altizer, Sonia; de Roode, Jacobus C.; Davis, Andrew K.

    2013-01-01

    Monarch butterflies (Danaus plexippus) throughout the world are commonly infected by the specialist pathogen Ophryocystis elektroscirrha (OE). This protozoan is transmitted when larvae ingest infectious stages (spores) scattered onto host plant leaves by infected adults. Parasites replicate internally during larval and pupal stages, and adult monarchs emerge covered with millions of dormant spores on the outsides of their bodies. Across multiple monarch populations, OE varies in prevalence and virulence. Here, we examined geographic and genetic variation in OE spore morphology using clonal parasite lineages derived from each of four host populations (eastern and western North America, South Florida and Hawaii). Spores were harvested from experimentally inoculated, captive-reared adult monarchs. Using light microscopy and digital image analysis, we measured the size, shape and color of 30 replicate spores per host. Analyses examined predictors of spore morphology, including parasite source population and clone, parasite load, and the following host traits: family line, sex, wing area, and wing color (orange and black pigmentation). Results showed significant differences in spore size and shape among parasite clones, suggesting genetic determinants of morphological variation. Spore size also increased with monarch wing size, and monarchs with larger and darker orange wings tended to have darker colored spores, consistent with the idea that parasite development depends on variation in host quality and resources. We found no evidence for effects of source population on variation in spore morphology. Collectively, these results provide support for heritable variation in spore morphology and a role for host traits in affecting parasite development. PMID:26462429

  10. Genetic evidence for female host-specific races of the common cuckoo.

    PubMed

    Gibbs, H L; Sorenson, M D; Marchetti, K; Brooke, M D; Davies, N B; Nakamura, H

    2000-09-14

    The common cuckoo Cuculus canorus is divided into host-specific races (gentes). Females of each race lay a distinctive egg type that tends to match the host's eggs, for instance, brown and spotted for meadow pipit hosts or plain blue for redstart hosts. The puzzle is how these gentes remain distinct. Here, we provide genetic evidence that gentes are restricted to female lineages, with cross mating by males maintaining the common cuckoo genetically as one species. We show that there is differentiation between gentes in maternally inherited mitochondrial DNA, but not in microsatellite loci of nuclear DNA. This supports recent behavioural evidence that female, but not male, common cuckoos specialize on a particular host, and is consistent with the possibility that genes affecting cuckoo egg type are located on the female-specific W sex chromosome. Our results also support the ideas that common cuckoos often switched hosts during evolution, and that some gentes may have multiple, independent origins, due to colonization by separate ancestral lineages.

  11. Genetic Diversity and Population Structure of Mycobacterium marinum: New Insights into Host and Environmental Specificities

    PubMed Central

    Broutin, Vincent; Bañuls, Anne-Laure; Aubry, Alexandra; Keck, Nicolas; Choisy, Marc; Bernardet, Jean-François; Michel, Christian; Raymond, Jean-Christophe; Libert, Cédric; Barnaud, Antoine; Stragier, Pieter; Portaels, Françoise; Terru, Dominique; Belon, Claudine; Dereure, Olivier; Gutierrez, Cristina; Boschiroli, Maria-Laura; Van De Perre, Philippe; Cambau, Emmanuelle

    2012-01-01

    Mycobacterium marinum causes a systemic tuberculosis-like disease in fish and skin infections in humans that can spread to deeper structures, resulting in tenosynovitis, arthritis, and osteomyelitis. However, little information is available concerning (i) the intraspecific genetic diversity of M. marinum isolated from humans and animals; (ii) M. marinum genotype circulation in the different ecosystems, and (iii) the link between M. marinum genetic diversity and hosts (humans and fish). Here, we conducted a genetic study on 89 M. marinum isolates from humans (n = 68) and fish (n = 21) by using mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) typing. The results show that the M. marinum population is genetically structured not only according to the host but also according to the ecosystem as well as to tissue tropism in humans. This suggests the existence of different genetic pools in the function of the biological and ecological compartments. Moreover, the presence of only certain M. marinum genotypes in humans suggests a different zoonotic potential of the M. marinum genotypes. Considering that the infection is linked to aquarium activity, a significant genetic difference was also detected when the human tissue tropism of M. marinum was taken into consideration, with a higher genetic polymorphism in strains isolated from patients with cutaneous forms than from individuals with deeper-structure infection. It appears that only few genotypes can produce deeper infections in humans, suggesting that the immune system might play a filtering role. PMID:22952269

  12. Health trajectories reveal the dynamic contributions of host genetic resistance and tolerance to infection outcome

    PubMed Central

    Lough, Graham; Kyriazakis, Ilias; Bergmann, Silke; Lengeling, Andreas; Doeschl-Wilson, Andrea B.

    2015-01-01

    Resistance and tolerance are two alternative strategies hosts can adopt to survive infections. Both strategies may be genetically controlled. To date, the relative contribution of resistance and tolerance to infection outcome is poorly understood. Here, we use a bioluminescent Listeria monocytogenes (Lm) infection challenge model to study the genetic determination and dynamic contributions of host resistance and tolerance to listeriosis in four genetically diverse mouse strains. Using conventional statistical analyses, we detect significant genetic variation in both resistance and tolerance, but cannot capture the time-dependent relative importance of either host strategy. We overcome these limitations through the development of novel statistical tools to analyse individual infection trajectories portraying simultaneous changes in infection severity and health. Based on these tools, early expression of resistance followed by expression of tolerance emerge as important hallmarks for surviving Lm infections. Our trajectory analysis further reveals that survivors and non-survivors follow distinct infection paths (which are also genetically determined) and provides new survival thresholds as objective endpoints in infection experiments. Future studies may use trajectories as novel traits for mapping and identifying genes that control infection dynamics and outcome. A Matlab script for user-friendly trajectory analysis is provided. PMID:26582028

  13. The influence of host genetics on erythrocytes and malaria infection: is there therapeutic potential?

    PubMed

    Lelliott, Patrick M; McMorran, Brendan J; Foote, Simon J; Burgio, Gaetan

    2015-07-29

    As parasites, Plasmodium species depend upon their host for survival. During the blood stage of their life-cycle parasites invade and reside within erythrocytes, commandeering host proteins and resources towards their own ends, and dramatically transforming the host cell. Parasites aptly avoid immune detection by minimizing the exposure of parasite proteins and removing themselves from circulation through cytoadherence. Erythrocytic disorders brought on by host genetic mutations can interfere with one or more of these processes, thereby providing a measure of protection against malaria to the host. This review summarizes recent findings regarding the mechanistic aspects of this protection, as mediated through the parasites interaction with abnormal erythrocytes. These novel findings include the reliance of the parasite on the host enzyme ferrochelatase, and the discovery of basigin and CD55 as obligate erythrocyte receptors for parasite invasion. The elucidation of these naturally occurring malaria resistance mechanisms is increasing the understanding of the host-parasite interaction, and as discussed below, is providing new insights into the development of therapies to prevent this disease.

  14. Ecological Genetics and Host Range Expansion by Busseola fusca (Lepidoptera: Noctuidae).

    PubMed

    Assefa, Y; Conlong, D E; Van Den Berg, J; Martin, L A

    2015-08-01

    The host plant range of pests can have important consequences for its evolution, and plays a critical role in the emergence and spread of a new pest outbreak. This study addresses the ecological genetics of the indigenous African maize stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae), in an attempt to investigate the evolutionary forces that may be involved in the recent host range expansion and establishment of this species in Ethiopian and southern African sugarcane. We used populations from Ethiopia, Zimbabwe, and South Africa to examine whether the host range expansion patterns shared by the Ethiopian and the southern African populations of B. fusca have evolved independently. Base-pair differences in the cytochrome oxidase I (COI) gene were used to characterize haplotype diversity and phylogenetic relationships. There were seven haplotypes among the 30 sequenced individuals collected on four host plant species from 17 localities in the four countries. Of the seven COI haplotypes identified, the two major ones occurred in both sugarcane and maize. Genetic analyses revealed no detectable genetic differentiation between southern African B. fusca populations from maize and sugarcane (FST = 0.019; P = 0.24). However, there was strong evidence of variation in genetic composition between populations of the pest from different geographic regions (FST = 0.948; P < 0.001). The main implication of these findings is that the B. fusca populations in maize in southern Africa are more likely to shift to sugarcane, suggesting that ecological opportunity is an important factor in host plant range expansion by a pest.

  15. Pseudomonas viridiflava, a Multi Host Plant Pathogen with Significant Genetic Variation at the Molecular Level

    PubMed Central

    Mpalantinaki, Evaggelia; Ververidis, Filippos; Goumas, Dimitrios E.

    2012-01-01

    The pectinolytic species Pseudomonas viridiflava has a wide host range among plants, causing foliar and stem necrotic lesions and basal stem and root rots. However, little is known about the molecular evolution of this species. In this study we investigated the intraspecies genetic variation of P. viridiflava amongst local (Cretan), as well as international isolates of the pathogen. The genetic and phenotypic variability were investigated by molecular fingerprinting (rep-PCR) and partial sequencing of three housekeeping genes (gyrB, rpoD and rpoB), and by biochemical and pathogenicity profiling. The biochemical tests and pathogenicity profiling did not reveal any variability among the isolates studied. However, the molecular fingerprinting patterns and housekeeping gene sequences clearly differentiated them. In a broader phylogenetic comparison of housekeeping gene sequences deposited in GenBank, significant genetic variability at the molecular level was found between isolates of P. viridiflava originated from different host species as well as among isolates from the same host. Our results provide a basis for more comprehensive understanding of the biology, sources and shifts in genetic diversity and evolution of P. viridiflava populations and should support the development of molecular identification tools and epidemiological studies in diseases caused by this species. PMID:22558343

  16. Host genetics of Epstein–Barr virus infection, latency and disease

    PubMed Central

    Houldcroft, Charlotte J; Kellam, Paul

    2015-01-01

    Epstein–Barr virus (EBV) infects 95% of the adult population and is the cause of infectious mononucleosis. It is also associated with 1% of cancers worldwide, such as nasopharyngeal carcinoma, Hodgkin's lymphoma and Burkitt's lymphoma. Human and cancer genetic studies are now major forces determining gene variants associated with many cancers, including nasopharyngeal carcinoma and Hodgkin's lymphoma. Host genetics is also important in infectious disease; however, there have been no large-scale efforts towards understanding the contribution that human genetic variation plays in primary EBV infection and latency. This review covers 25 years of studies into host genetic susceptibility to EBV infection and disease, from candidate gene studies, to the first genome-wide association study of EBV antibody response, and an EBV-status stratified genome-wide association study of Hodgkin's lymphoma. Although many genes are implicated in EBV-related disease, studies are often small, not replicated or followed up in a different disease. Larger, appropriately powered genomic studies to understand the host response to EBV will be needed to move our understanding of the biology of EBV infection beyond the handful of genes currently identified. Fifty years since the discovery of EBV and its identification as a human oncogenic virus, a glimpse of the future is shown by the first whole-genome and whole-exome studies, revealing new human genes at the heart of the host–EBV interaction. © 2014 The Authors. Reviews in Medical Virology published by John Wiley & Sons Ltd. PMID:25430668

  17. Genetic and Transcriptional Analysis of Human Host Response to Healthy Gut Microbiota

    PubMed Central

    Richards, Allison L.; Burns, Michael B.; Alazizi, Adnan; Barreiro, Luis B.; Pique-Regi, Roger

    2016-01-01

    ABSTRACT Many studies have demonstrated the importance of the gut microbiota in healthy and disease states. However, establishing the causality of host-microbiota interactions in humans is still challenging. Here, we describe a novel experimental system to define the transcriptional response induced by the microbiota for human cells and to shed light on the molecular mechanisms underlying host-gut microbiota interactions. In primary human colonic epithelial cells, we identified over 6,000 genes whose expression changed at various time points following coculturing with the gut microbiota of a healthy individual. Among the differentially expressed genes we found a 1.8-fold enrichment of genes associated with diseases that have been previously linked to the microbiome, such as obesity and colorectal cancer. In addition, our experimental system allowed us to identify 87 host single nucleotide polymorphisms (SNPs) that show allele-specific expression in 69 genes. Furthermore, for 12 SNPs in 12 different genes, allele-specific expression is conditional on the exposure to the microbiota. Of these 12 genes, 8 have been associated with diseases linked to the gut microbiota, specifically colorectal cancer, obesity, and type 2 diabetes. Our study demonstrates a scalable approach to study host-gut microbiota interactions and can be used to identify putative mechanisms for the interplay between host genetics and the microbiota in health and disease. IMPORTANCE The study of host-microbiota interactions in humans is largely limited to identifying associations between microbial communities and host phenotypes. While these studies have generated important insights on the links between the microbiota and human disease, the assessment of cause-and-effect relationships has been challenging. Although this relationship can be studied in germfree mice, this system is costly, and it is difficult to accurately account for the effects of host genotypic variation and environmental effects

  18. Genetic Structure of Natural Populations of Escherichia coli in Wild Hosts on Different Continents

    PubMed Central

    Souza, Valeria; Rocha, Martha; Valera, Aldo; Eguiarte, Luis E.

    1999-01-01

    Current knowledge of genotypic and phenotypic diversity in the species Escherichia coli is based almost entirely on strains recovered from humans or zoo animals. In this study, we analyzed a collection of 202 strains obtained from 81 mammalian species representing 39 families and 14 orders in Australia and the Americas, as well as several reference strains; we also included a strain from a reptile and 10 from different families of birds collected in Mexico. The strains were characterized genotypically by multilocus enzyme electrophoresis (MLEE) and phenotypically by patterns of sugar utilization, antibiotic resistance, and plasmid profile. MLEE analysis yielded an estimated genetic diversity (H) of 0.682 for 11 loci. The observed genetic diversity in this sample is the greatest yet reported for E. coli. However, this genetic diversity is not randomly distributed; geographic effects and host taxonomic group accounted for most of the genetic differentiation. The genetic relationship among the strains showed that they are more associated by origin and host order than is expected by chance. In a dendrogram, the ancestral cluster includes primarily strains from Australia and ECOR strains from groups B and C. The most differentiated E. coli in our analysis are strains from Mexican carnivores and strains from humans, including those in the ECOR group A. The kinds and numbers of sugars utilized by the strains varied by host taxonomic group and country of origin. Strains isolated from bats were found to exploit the greatest range of sugars, while those from primates utilized the fewest. Toxins are more frequent in strains from rodents from both continents than in any other taxonomic group. Strains from Mexican wild mammals were, on average, as resistant to antibiotics as strains from humans in cities. On average, the Australian strains presented a lower antibiotic resistance than the Mexican strains. However, strains recovered from hosts in cities carried significantly more

  19. Host-plant-associated genetic differentiation in Northern French populations of the European corn borer.

    PubMed

    Martel, C; Réjasse, A; Rousset, F; Bethenod, M-T; Bourguet, D

    2003-02-01

    The phytophagous insects that damage crops are often polyphagous, feeding on several types of crop and on weeds. The refuges constituted by noncrop host plants may be useful in managing the evolution in pest species of resistance to the Bacillus thuringiensis toxins produced by transgenic crops. However, the benefits of these refuges may be limited because host-plant diversity may drive genetic divergence and possibly even host-plant-mediated sympatric speciation. The European corn borer, Ostrinia nubilalis Hübner (Lepidoptera: Crambidae), is the main pest of maize in Europe and North America, where it was introduced early in the 20th century. It has a wide host range but feeds principally on mugwort (Artemisia vulgaris L.) and maize (Zea mays L.). O. nubilalis is found on mugwort only in the northern part of France, whereas it is found on maize throughout France. The extent of genetic variation at allozyme markers was investigated in populations collected from the two host plants over the entire geographical distribution of the European corn borer on mugwort in France. Allelic differentiation between pairs of populations and hierarchical analyses of pools of samples from each host plant indicate that the group of populations feeding on maize differed from the group of populations feeding on mugwort. Our results suggest (1) host-plant-related divergent selection at the genomic region surrounding the Mpi locus and (2) limited gene flow between the populations feeding on mugwort and those infesting maize fields. These data indicate that adults emerging from mugwort would not be useful for managing the evolution of resistance to the B. thuringiensis toxins in European corn borer populations.

  20. Xylitol production by yeasts isolated from rotting wood in the Galápagos Islands, Ecuador, and description of Cyberlindnera galapagoensis f.a., sp. nov.

    PubMed

    Guamán-Burneo, Maria C; Dussán, Kelly J; Cadete, Raquel M; Cheab, Monaliza A M; Portero, Patricia; Carvajal-Barriga, Enrique J; da Silva, Sílvio S; Rosa, Carlos A

    2015-10-01

    This study evaluated D-xylose-assimilating yeasts that are associated with rotting wood from the Galápagos Archipelago, Ecuador, for xylitol production from hemicellulose hydrolysates. A total of 140 yeast strains were isolated. Yeasts related to the clades Yamadazyma, Kazachstania, Kurtzmaniella, Lodderomyces, Metschnikowia and Saturnispora were predominant. In culture assays using sugarcane bagasse hemicellulose hydrolysate, Candida tropicalis CLQCA-24SC-125 showed the highest xylitol production, yield and productivity (27.1 g L(-1) xylitol, Y p/s (xyl) = 0.67 g g(-1), Qp = 0.38 g L(-1). A new species of Cyberlindnera, strain CLQCA-24SC-025, was responsible for the second highest xylitol production (24 g L(-1), Y p/s (xyl) = 0.64 g g(-1), Qp = 0.33 g L(-1) h(-1)) on sugarcane hydrolysate. The new xylitol-producing species Cyberlindnera galapagoensis f.a., sp. nov., is proposed to accommodate the strain CLQCA-24SC-025(T) (=UFMG-CM-Y517(T); CBS 13997(T)). The MycoBank number is MB 812171.

  1. Inbreeding within human Schistosoma mansoni: do host-specific factors shape the genetic composition of parasite populations?

    PubMed Central

    Van den Broeck, F; Meurs, L; Raeymaekers, J A M; Boon, N; Dieye, T N; Volckaert, F A M; Polman, K; Huyse, T

    2014-01-01

    The size, structure and distribution of host populations are key determinants of the genetic composition of parasite populations. Despite the evolutionary and epidemiological merits, there has been little consideration of how host heterogeneities affect the evolutionary trajectories of parasite populations. We assessed the genetic composition of natural populations of the parasite Schistosoma mansoni in northern Senegal. A total of 1346 parasites were collected from 14 snail and 57 human hosts within three villages and individually genotyped using nine microsatellite markers. Human host demographic parameters (age, gender and village of residence) and co-infection with Schistosoma haematobium were documented, and S. mansoni infection intensities were quantified. F-statistics and clustering analyses revealed a random distribution (panmixia) of parasite genetic variation among villages and hosts, confirming the concept of human hosts as ‘genetic mixing bowls' for schistosomes. Host gender and village of residence did not show any association with parasite genetics. Host age, however, was significantly correlated with parasite inbreeding and heterozygosity, with children being more infected by related parasites than adults. The patterns may be explained by (1) genotype-dependent ‘concomitant immunity' that leads to selective recruitment of genetically unrelated worms with host age, and/or (2) the ‘genetic mixing bowl' hypothesis, where older hosts have been exposed to a wider variety of parasite strains than children. The present study suggests that host-specific factors may shape the genetic composition of schistosome populations, revealing important insights into host–parasite interactions within a natural system. PMID:24619176

  2. Genetic Markers of the Host in Persons Living with HTLV-1, HIV and HCV Infections.

    PubMed

    Assone, Tatiane; Paiva, Arthur; Fonseca, Luiz Augusto M; Casseb, Jorge

    2016-02-03

    Human T-cell leukemia virus type 1 (HTLV-1), hepatitis C virus (HCV) and human immunodeficiency virus type 1 (HIV-1) are prevalent worldwide, and share similar means of transmission. These infections may influence each other in evolution and outcome, including cancer or immunodeficiency. Many studies have reported the influence of genetic markers on the host immune response against different persistent viral infections, such as HTLV-1 infection, pointing to the importance of the individual genetic background on their outcomes. However, despite recent advances on the knowledge of the pathogenesis of HTLV-1 infection, gaps in the understanding of the role of the individual genetic background on the progress to disease clinically manifested still remain. In this scenario, much less is known regarding the influence of genetic factors in the context of dual or triple infections or their influence on the underlying mechanisms that lead to outcomes that differ from those observed in monoinfection. This review describes the main factors involved in the virus-host balance, especially for some particular human leukocyte antigen (HLA) haplotypes, and other important genetic markers in the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and other persistent viruses, such as HIV and HCV.

  3. Genetic Markers of the Host in Persons Living with HTLV-1, HIV and HCV Infections

    PubMed Central

    Assone, Tatiane; Paiva, Arthur; Fonseca, Luiz Augusto M.; Casseb, Jorge

    2016-01-01

    Human T-cell leukemia virus type 1 (HTLV-1), hepatitis C virus (HCV) and human immunodeficiency virus type 1 (HIV-1) are prevalent worldwide, and share similar means of transmission. These infections may influence each other in evolution and outcome, including cancer or immunodeficiency. Many studies have reported the influence of genetic markers on the host immune response against different persistent viral infections, such as HTLV-1 infection, pointing to the importance of the individual genetic background on their outcomes. However, despite recent advances on the knowledge of the pathogenesis of HTLV-1 infection, gaps in the understanding of the role of the individual genetic background on the progress to disease clinically manifested still remain. In this scenario, much less is known regarding the influence of genetic factors in the context of dual or triple infections or their influence on the underlying mechanisms that lead to outcomes that differ from those observed in monoinfection. This review describes the main factors involved in the virus–host balance, especially for some particular human leukocyte antigen (HLA) haplotypes, and other important genetic markers in the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and other persistent viruses, such as HIV and HCV. PMID:26848682

  4. Alteration of Genetic Make-up in Karnal Bunt Pathogen (Tilletia indica) of Wheat in Presence of Host Determinants

    PubMed Central

    Gupta, Atul K.; Seneviratne, J. M.; Bala, Ritu; Jaiswal, J. P.; Kumar, Anil

    2015-01-01

    Alteration of genetic make-up of the isolates and monosporidial strains of Tilletia indica causing Karnal bunt (KB) disease in wheat was analyzed using DNA markers and SDS-PAGE. The generation of new variation with different growth characteristics is not a generalized feature and is not only dependant on the original genetic make up of the base isolate/monosporidial strains but also on interaction with host. Host determinant(s) plays a significant role in the generation of variability and the effect is much pronounced in monosporidial strains with narrow genetic base as compared to broad genetic base. The most plausible explanation of genetic variation in presence of host determinant(s) are the recombination of genetic material from two different mycelial/sporidia through sexual mating as well as through para-sexual means. The morphological and development dependent variability further suggests that the variation in T. indica strains predominantly derived through the genetic rearrangements. PMID:26060428

  5. Differential Host Plant-Associated Genetic Variation Between Sympatric Mite Species of the Genus Oligonychus (Acari: Tetranychidae).

    PubMed

    Guzman-Valencia, Stephanie; Santillán-Galicia, Ma Teresa; Guzmán-Franco, Ariel W; Vega-Muñoz, Ricardo

    2017-01-12

    Adaptation to different host plants can lead to host-associated differentiation (HAD). The mites Oligonychus perseae and Oligonychus punicae have a broad range of host plants, but, to date, records of them coexisting sympatrically had only been reported on avocado. However, our field observations showed both species coexisting on host plants other than avocado. The lack of previous records of these mites on the host plants studied here suggests only recent divergence to new host plant species. Previous studies showed that O. punicae had a limited migration capacity compared with O. perseae, suggesting that O. punicae is more likely to develop a close host plant relationship leading to HAD. Adults of both species were collected from trees hosting both mite species. Three genera of host plants considered were Persea, Salix, and Alnus; two species within one genus were Alnus jorullensis and Alnus acuminata; and three varieties within one species were Persea americana var. Fuerte, var. Hass, and var. Criollo, a noncommercial variety. Using sequence data from a segment of the mitochondrial cytochrome oxidase subunit I, the phylogenetic relationships and genetic population structure of both mite species in relation to the host plant were determined. Oligonychus perseae populations showed a significant population structure in relation to host plant at the species and genus level, but there was no effect of variety. In contrast, host plant explained none of the genetic variation among O. punicae populations. The potential role of coexistence mechanisms in the contrasting genetic population structure of both mite species is discussed.

  6. Identification of Host Genes Involved in Geminivirus Infection Using a Reverse Genetics Approach

    PubMed Central

    Luna, Ana P.; Bejarano, Eduardo R.

    2011-01-01

    Geminiviruses, like all viruses, rely on the host cell machinery to establish a successful infection, but the identity and function of these required host proteins remain largely unknown. Tomato yellow leaf curl Sardinia virus (TYLCSV), a monopartite geminivirus, is one of the causal agents of the devastating Tomato yellow leaf curl disease (TYLCD). The transgenic 2IRGFP N. benthamiana plants, used in combination with Virus Induced Gene Silencing (VIGS), entail an important potential as a tool in reverse genetics studies to identify host factors involved in TYLCSV infection. Using these transgenic plants, we have made an accurate description of the evolution of TYLCSV replication in the host in both space and time. Moreover, we have determined that TYLCSV and Tobacco rattle virus (TRV) do not dramatically influence each other when co-infected in N. benthamiana, what makes the use of TRV-induced gene silencing in combination with TYLCSV for reverse genetic studies feasible. Finally, we have tested the effect of silencing candidate host genes on TYLCSV infection, identifying eighteen genes potentially involved in this process, fifteen of which had never been implicated in geminiviral infections before. Seven of the analyzed genes have a potential anti-viral effect, whereas the expression of the other eleven is required for a full infection. Interestingly, almost half of the genes altering TYLCSV infection play a role in postranslational modifications. Therefore, our results provide new insights into the molecular mechanisms underlying geminivirus infections, and at the same time reveal the 2IRGFP/VIGS system as a powerful tool for functional reverse genetics studies. PMID:21818318

  7. Host use evolution in Chrysochus milkweed beetles: evidence from behaviour, population genetics and phylogeny.

    PubMed

    Dobler, S; Farrell, B D

    1999-08-01

    In two sister species of leaf beetles with overlapping host associations, Chrysochus auratus and C. cobaltinus, we established diet breadth and food preference of local populations for evaluation together with genetic differentiation between populations. While C. auratus turned out to be monophagous on the same plant wherever we collected the beetles, the studied populations of C. cobaltinus fed on three different plant species in the field. Plant preference and ranking of the potential host plants significantly differed between these populations. The amount of genetic differentiation between populations was measured by a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay of a 1300 bp mitochondrial DNA (mtDNA) sequence. In addition, the dominant genotypes of all populations were sequenced. No genetic differentiation between the populations of C. auratus could be detected in the RFLP assay and sequence divergence was low (= 0.3%). In C. cobaltinus, on the other hand, genetic differentiation between populations was high, revealing a lack of gene flow over a much smaller scale and a maximum of 1.3% sequence divergence. C. cobaltinus thereby has the prerequisites for host race formation on different plants from the original host spectrum. Our sequence-based phylogeny estimate allows us to reconstruct historical diet evolution in Chrysochus. Starting from an original association with Asclepiadaceae, the common ancestor of C. auratus and C. cobaltinus included Apocynaceae in its diet. The strict specialization on Apocynum and the loss of acceptance of Asclepiadaceae observed in C. auratus could have resulted from a process similar to that displayed by C. cobaltinus populations.

  8. Interactions Within Susceptible Hosts Drive Establishment of Genetically Distinct Variants of an Insect-Borne Pathogen.

    PubMed

    Blaisdell, G K; Zhang, S; Bratburd, J R; Daane, K M; Cooper, M L; Almeida, R P P

    2015-08-01

    Coinfections are common, leading to pathogen interactions during transmission and establishment in a host. However, few studies have tested the relative strengths of pathogen interactions in vectors and hosts that determine the outcome of infection. We tested interactions between two genetically distinct variants of the mealybug-transmitted Grapevine leafroll-associated virus 3. The transmission efficiency of each variant in single variant inoculations by two vector species was determined. The effects of vector species, a coinfected source, and simultaneous inoculation from multiple hosts to one host on variant establishment were examined. Within-vector interactions could have a role in transmission from hosts containing mixed infections, but not when vectors were moved from separate singly infected source plants to a single recipient plant. The invasive Planococcus ficus (Signoret) was a more efficient vector than Pseudococcus viburni (Signoret). Transmission efficiency of the two variants did not differ in single variant inoculations. Overall infections were the same whether from singly or coinfected source plants. In mixed inoculations, establishment of one variant was reduced. Mixed inoculations from two singly infected source plants resulted in fewer mixed infections than expected by chance. Therefore, the observed outcome was determined subsequent to host inoculation rather than in the vector. The outcome may be due to resource competition between pathogens. Alternatively apparent competition may be responsible; the pathogens' differential ability to overcome host defenses and colonize the host may determine the final outcome of new infections. Detailed knowledge of interactions between pathogens during transmission and establishment could improve understanding and management of disease spread.

  9. Genetic changes accompanying the evolution of host specialization in Drosophila sechellia.

    PubMed

    Dworkin, Ian; Jones, Corbin D

    2009-02-01

    Changes in host specialization contribute to the diversification of phytophagous insects. When shifting to a new host, insects evolve new physiological, morphological, and behavioral adaptations. Our understanding of the genetic changes responsible for these adaptations is limited. For instance, we do not know how often host shifts involve gain-of-function vs. loss-of-function alleles. Recent work suggests that some genes involved in odor recognition are lost in specialists. Here we show that genes involved in detoxification and metabolism, as well as those affecting olfaction, have reduced gene expression in Drosophila sechellia-a specialist on the fruit of Morinda citrifolia. We screened for genes that differ in expression between D. sechellia and its generalist sister species, D. simulans. We also screened for genes that are differentially expressed in D. sechellia when these flies chose their preferred host vs. when they were forced onto other food. D. sechellia increases expression of genes involved with oogenesis and fatty acid metabolism when on its host. The majority of differentially expressed genes, however, appear downregulated in D. sechellia. For several functionally related genes, this decrease in expression is associated with apparent loss-of-function alleles. For example, the D. sechellia allele of Odorant binding protein 56e (Obp56e) harbors a premature stop codon. We show that knockdown of Obp56e activity significantly reduces the avoidance response of D. melanogaster toward M. citrifolia. We argue that apparent loss-of-function alleles like Obp56e potentially contributed to the initial adaptation of D. sechellia to its host. Our results suggest that a subset of genes reduce or lose function as a consequence of host specialization, which may explain why, in general, specialist insects tend to shift to chemically similar hosts.

  10. Genetic Changes Accompanying the Evolution of Host Specialization in Drosophila sechellia

    PubMed Central

    Dworkin, Ian; Jones, Corbin D.

    2009-01-01

    Changes in host specialization contribute to the diversification of phytophagous insects. When shifting to a new host, insects evolve new physiological, morphological, and behavioral adaptations. Our understanding of the genetic changes responsible for these adaptations is limited. For instance, we do not know how often host shifts involve gain-of-function vs. loss-of-function alleles. Recent work suggests that some genes involved in odor recognition are lost in specialists. Here we show that genes involved in detoxification and metabolism, as well as those affecting olfaction, have reduced gene expression in Drosophila sechellia—a specialist on the fruit of Morinda citrifolia. We screened for genes that differ in expression between D. sechellia and its generalist sister species, D. simulans. We also screened for genes that are differentially expressed in D. sechellia when these flies chose their preferred host vs. when they were forced onto other food. D. sechellia increases expression of genes involved with oogenesis and fatty acid metabolism when on its host. The majority of differentially expressed genes, however, appear downregulated in D. sechellia. For several functionally related genes, this decrease in expression is associated with apparent loss-of-function alleles. For example, the D. sechellia allele of Odorant binding protein 56e (Obp56e) harbors a premature stop codon. We show that knockdown of Obp56e activity significantly reduces the avoidance response of D. melanogaster toward M. citrifolia. We argue that apparent loss-of-function alleles like Obp56e potentially contributed to the initial adaptation of D. sechellia to its host. Our results suggest that a subset of genes reduce or lose function as a consequence of host specialization, which may explain why, in general, specialist insects tend to shift to chemically similar hosts. PMID:19033155

  11. Bovine Host Genetic Variation Influences Rumen Microbial Methane Production with Best Selection Criterion for Low Methane Emitting and Efficiently Feed Converting Hosts Based on Metagenomic Gene Abundance

    PubMed Central

    Roehe, Rainer; Dewhurst, Richard J.; Duthie, Carol-Anne; Rooke, John A.; McKain, Nest; Ross, Dave W.; Hyslop, Jimmy J.; Waterhouse, Anthony; Freeman, Tom C.

    2016-01-01

    Methane produced by methanogenic archaea in ruminants contributes significantly to anthropogenic greenhouse gas emissions. The host genetic link controlling microbial methane production is unknown and appropriate genetic selection strategies are not developed. We used sire progeny group differences to estimate the host genetic influence on rumen microbial methane production in a factorial experiment consisting of crossbred breed types and diets. Rumen metagenomic profiling was undertaken to investigate links between microbial genes and methane emissions or feed conversion efficiency. Sire progeny groups differed significantly in their methane emissions measured in respiration chambers. Ranking of the sire progeny groups based on methane emissions or relative archaeal abundance was consistent overall and within diet, suggesting that archaeal abundance in ruminal digesta is under host genetic control and can be used to genetically select animals without measuring methane directly. In the metagenomic analysis of rumen contents, we identified 3970 microbial genes of which 20 and 49 genes were significantly associated with methane emissions and feed conversion efficiency respectively. These explained 81% and 86% of the respective variation and were clustered in distinct functional gene networks. Methanogenesis genes (e.g. mcrA and fmdB) were associated with methane emissions, whilst host-microbiome cross talk genes (e.g. TSTA3 and FucI) were associated with feed conversion efficiency. These results strengthen the idea that the host animal controls its own microbiota to a significant extent and open up the implementation of effective breeding strategies using rumen microbial gene abundance as a predictor for difficult-to-measure traits on a large number of hosts. Generally, the results provide a proof of principle to use the relative abundance of microbial genes in the gastrointestinal tract of different species to predict their influence on traits e.g. human metabolism

  12. Bovine Host Genetic Variation Influences Rumen Microbial Methane Production with Best Selection Criterion for Low Methane Emitting and Efficiently Feed Converting Hosts Based on Metagenomic Gene Abundance.

    PubMed

    Roehe, Rainer; Dewhurst, Richard J; Duthie, Carol-Anne; Rooke, John A; McKain, Nest; Ross, Dave W; Hyslop, Jimmy J; Waterhouse, Anthony; Freeman, Tom C; Watson, Mick; Wallace, R John

    2016-02-01

    Methane produced by methanogenic archaea in ruminants contributes significantly to anthropogenic greenhouse gas emissions. The host genetic link controlling microbial methane production is unknown and appropriate genetic selection strategies are not developed. We used sire progeny group differences to estimate the host genetic influence on rumen microbial methane production in a factorial experiment consisting of crossbred breed types and diets. Rumen metagenomic profiling was undertaken to investigate links between microbial genes and methane emissions or feed conversion efficiency. Sire progeny groups differed significantly in their methane emissions measured in respiration chambers. Ranking of the sire progeny groups based on methane emissions or relative archaeal abundance was consistent overall and within diet, suggesting that archaeal abundance in ruminal digesta is under host genetic control and can be used to genetically select animals without measuring methane directly. In the metagenomic analysis of rumen contents, we identified 3970 microbial genes of which 20 and 49 genes were significantly associated with methane emissions and feed conversion efficiency respectively. These explained 81% and 86% of the respective variation and were clustered in distinct functional gene networks. Methanogenesis genes (e.g. mcrA and fmdB) were associated with methane emissions, whilst host-microbiome cross talk genes (e.g. TSTA3 and FucI) were associated with feed conversion efficiency. These results strengthen the idea that the host animal controls its own microbiota to a significant extent and open up the implementation of effective breeding strategies using rumen microbial gene abundance as a predictor for difficult-to-measure traits on a large number of hosts. Generally, the results provide a proof of principle to use the relative abundance of microbial genes in the gastrointestinal tract of different species to predict their influence on traits e.g. human metabolism

  13. Gut Microbiome and Infant Health: Brain-Gut-Microbiota Axis and Host Genetic Factors

    PubMed Central

    Cong, Xiaomei; Xu, Wanli; Romisher, Rachael; Poveda, Samantha; Forte, Shaina; Starkweather, Angela; Henderson, Wendy A.

    2016-01-01

    The development of the neonatal gut microbiome is influenced by multiple factors, such as delivery mode, feeding, medication use, hospital environment, early life stress, and genetics. The dysbiosis of gut microbiota persists during infancy, especially in high-risk preterm infants who experience lengthy stays in the Neonatal intensive care unit (NICU). Infant microbiome evolutionary trajectory is essentially parallel with the host (infant) neurodevelopmental process and growth. The role of the gut microbiome, the brain-gut signaling system, and its interaction with the host genetics have been shown to be related to both short and long term infant health and bio-behavioral development. The investigation of potential dysbiosis patterns in early childhood is still lacking and few studies have addressed this host-microbiome co-developmental process. Further research spanning a variety of fields of study is needed to focus on the mechanisms of brain-gut-microbiota signaling system and the dynamic host-microbial interaction in the regulation of health, stress and development in human newborns. PMID:27698614

  14. Gut Microbiome and Infant Health: Brain-Gut-Microbiota Axis and Host Genetic Factors.

    PubMed

    Cong, Xiaomei; Xu, Wanli; Romisher, Rachael; Poveda, Samantha; Forte, Shaina; Starkweather, Angela; Henderson, Wendy A

    2016-09-01

    The development of the neonatal gut microbiome is influenced by multiple factors, such as delivery mode, feeding, medication use, hospital environment, early life stress, and genetics. The dysbiosis of gut microbiota persists during infancy, especially in high-risk preterm infants who experience lengthy stays in the Neonatal intensive care unit (NICU). Infant microbiome evolutionary trajectory is essentially parallel with the host (infant) neurodevelopmental process and growth. The role of the gut microbiome, the brain-gut signaling system, and its interaction with the host genetics have been shown to be related to both short and long term infant health and bio-behavioral development. The investigation of potential dysbiosis patterns in early childhood is still lacking and few studies have addressed this host-microbiome co-developmental process. Further research spanning a variety of fields of study is needed to focus on the mechanisms of brain-gut-microbiota signaling system and the dynamic host-microbial interaction in the regulation of health, stress and development in human newborns.

  15. Effects of host genetics and environment on egg-associated microbiotas in brown trout (Salmo trutta).

    PubMed

    Wilkins, Laetitia G E; Fumagalli, Luca; Wedekind, Claus

    2016-10-01

    Recent studies found fish egg-specific bacterial communities that changed over the course of embryogenesis, suggesting an interaction between the developing host and its microbiota. Indeed, single-strain infections demonstrated that the virulence of opportunistic bacteria is influenced by environmental factors and host immune genes. However, the interplay between a fish embryo host and its microbiota has not been studied yet at the community level. To test whether host genetics affects the assemblage of egg-associated bacteria, adult brown trout (Salmo trutta) were sampled from a natural population. Their gametes were used for full-factorial in vitro fertilizations to separate sire from dam effects. In total, 2520 embryos were singly raised under experimental conditions that differently support microbial growth. High-throughput 16S rRNA amplicon sequencing was applied to characterize bacterial communities on milt and fertilized eggs across treatments. Dam and sire identity influenced embryo mortality, time until hatching and composition of egg-associated microbiotas, but no link between bacterial communities on milt and on fertilized eggs could be found. Elevated resources increased embryo mortality and modified bacterial communities with a shift in their putative functional potential. Resource availability did not significantly affect any parental effects on embryo performance. Sire identity affected bacterial diversity that turned out to be a significant predictor of hatching time: embryos associated with high bacterial diversity hatched later. We conclude that both host genetics and the availability of resources define diversity and composition of egg-associated bacterial communities that then affect the life history of their hosts.

  16. Rapid turnover of intra-host genetic diversity in Zucchini yellow mosaic virus

    PubMed Central

    Simmons, Heather E.; Holmes, Edward C.; Stephenson, Andrew G.

    2010-01-01

    Genetic diversity in RNA viruses is shaped by a variety of evolutionary processes, including the bottlenecks that may occur at inter-host transmission. However, how these processes structure genetic variation at the scale of individual hosts is only partly understood. We obtained intra-host sequence data for the coat protein (CP) gene of Zucchini yellow mosaic virus (ZYMV) from two horizontally transmitted populations – one via aphid, the other without – and with multiple samples from individual plants. We show that although mutations are generated relatively frequently within infected plants, attaining similar levels of genetic diversity to that seen in some animal RNA viruses (mean intra-sample diversity of 0.02%), most mutations are likely to be transient, deleterious, and purged rapidly. We also observed more population structure in the aphid transmitted viral population, including the same mutations in multiple clones, the presence of a sub-lineage, and evidence for the short-term complementation of defective genomes. PMID:21138748

  17. Identification of genetic loci that control mammary tumor susceptibility through the host microenvironment

    DOE PAGES

    Zhang, Pengju; Lo, Alvin; Huang, Yurong; ...

    2015-03-09

    The interplay between host genetics, tumor microenvironment and environmental exposure in cancer susceptibility remains poorly understood. Here we assessed the genetic control of stromal mediation of mammary tumor susceptibility to low dose ionizing radiation (LDIR) using backcrossed F1 into BALB/c (F1Bx) between cancer susceptible (BALB/c) and resistant (SPRET/EiJ) mouse strains. Tumor formation was evaluated after transplantation of non-irradiated Trp53-/- BALB/c mammary gland fragments into cleared fat pads of F1Bx hosts. Genome-wide linkage analysis revealed 2 genetic loci that constitute the baseline susceptibility via host microenvironment. However, once challenged with LDIR, we discovered 13 additional loci that were enriched for genesmore » involved in cytokines, including TGFβ1 signaling. Surprisingly, LDIR-treated F1Bx cohort significantly reduced incidence of mammary tumors from Trp53-/- fragments as well as prolonged tumor latency, compared to sham-treated controls. We demonstrated further that plasma levels of specific cytokines were significantly correlated with tumor latency. Using an ex vivo 3-D assay, we confirmed TGFβ1 as a strong candidate for reduced mammary invasion in SPRET/EiJ, which could explain resistance of this strain to mammary cancer risk following LDIR. Our results open possible new avenues to understand mechanisms of genes operating via the stroma that affect cancer risk from external environmental exposures.« less

  18. Identification of genetic loci that control mammary tumor susceptibility through the host microenvironment

    SciTech Connect

    Zhang, Pengju; Lo, Alvin; Huang, Yurong; Huang, Ge; Liang, Guozhou; Mott, Joni; Karpen, Gary H.; Blakely, Eleanor A.; Bissell, Mina J.; Barcellos-Hoff, Mary Helen; Snijders, Antoine M.; Mao, Jian-Hua

    2015-03-09

    The interplay between host genetics, tumor microenvironment and environmental exposure in cancer susceptibility remains poorly understood. Here we assessed the genetic control of stromal mediation of mammary tumor susceptibility to low dose ionizing radiation (LDIR) using backcrossed F1 into BALB/c (F1Bx) between cancer susceptible (BALB/c) and resistant (SPRET/EiJ) mouse strains. Tumor formation was evaluated after transplantation of non-irradiated Trp53-/- BALB/c mammary gland fragments into cleared fat pads of F1Bx hosts. Genome-wide linkage analysis revealed 2 genetic loci that constitute the baseline susceptibility via host microenvironment. However, once challenged with LDIR, we discovered 13 additional loci that were enriched for genes involved in cytokines, including TGFβ1 signaling. Surprisingly, LDIR-treated F1Bx cohort significantly reduced incidence of mammary tumors from Trp53-/- fragments as well as prolonged tumor latency, compared to sham-treated controls. We demonstrated further that plasma levels of specific cytokines were significantly correlated with tumor latency. Using an ex vivo 3-D assay, we confirmed TGFβ1 as a strong candidate for reduced mammary invasion in SPRET/EiJ, which could explain resistance of this strain to mammary cancer risk following LDIR. Our results open possible new avenues to understand mechanisms of genes operating via the stroma that affect cancer risk from external environmental exposures.

  19. Murine Gut Microbiota Is Defined by Host Genetics and Modulates Variation of Metabolic Traits

    PubMed Central

    Lu, Lu; Williams, Evan G.; Brewer, Simon; Andreux, Pénélope A.; Bastiaansen, John W. M.; Wang, Xusheng; Kachman, Stephen D.; Auwerx, Johan; Williams, Robert W.; Benson, Andrew K.; Peterson, Daniel A.; Ciobanu, Daniel C.

    2012-01-01

    The gastrointestinal tract harbors a complex and diverse microbiota that has an important role in host metabolism. Microbial diversity is influenced by a combination of environmental and host genetic factors and is associated with several polygenic diseases. In this study we combined next-generation sequencing, genetic mapping, and a set of physiological traits of the BXD mouse population to explore genetic factors that explain differences in gut microbiota and its impact on metabolic traits. Molecular profiling of the gut microbiota revealed important quantitative differences in microbial composition among BXD strains. These differences in gut microbial composition are influenced by host-genetics, which is complex and involves many loci. Linkage analysis defined Quantitative Trait Loci (QTLs) restricted to a particular taxon, branch or that influenced the variation of taxa across phyla. Gene expression within the gastrointestinal tract and sequence analysis of the parental genomes in the QTL regions uncovered candidate genes with potential to alter gut immunological profiles and impact the balance between gut microbial communities. A QTL region on Chr 4 that overlaps several interferon genes modulates the population of Bacteroides, and potentially Bacteroidetes and Firmicutes–the predominant BXD gut phyla. Irak4, a signaling molecule in the Toll-like receptor pathways is a candidate for the QTL on Chr15 that modulates Rikenellaceae, whereas Tgfb3, a cytokine modulating the barrier function of the intestine and tolerance to commensal bacteria, overlaps a QTL on Chr 12 that influence Prevotellaceae. Relationships between gut microflora, morphological and metabolic traits were uncovered, some potentially a result of common genetic sources of variation. PMID:22723961

  20. Evidence for Within-Host Genetic Recombination among the Human Pegiviral Strains in HIV Infected Subjects.

    PubMed

    Wu, Haoming; Padhi, Abinash; Xu, Junqiang; Gong, Xiaoyan; Tien, Po

    2016-01-01

    The non-pathogenic Human Pegivirus (HPgV, formerly GBV-C/HGV), the most prevalent RNA virus worldwide, is known to be associated with reduced morbidity and mortality in HIV-infected individuals. Although previous studies documented its ubiquity and important role in HIV-infected individuals, little is known about the underlying genetic mechanisms that maintain high genetic diversity of HPgV within the HIV-infected individuals. To assess the within-host genetic diversity of HPgV and forces that maintain such diversity within the co-infected hosts, we performed phylogenetic analyses taking into account 229 HPgV partial E1-E2 clonal sequences representing 15 male and 8 female co-infected HIV patients from Hubei province of central China. Our results revealed the presence of eleven strongly supported clades. While nine clades belonged to genotype 3, two clades belonged to genotype 2. Additionally, four clades that belonged to genotype 3 exhibited inter-clade recombination events. The presence of clonal sequences representing multiple clades within the HIV-infected individual provided the evidence of co-circulation of HPgV strains across the region. Of the 23 patients, six patients (i.e., five males and one female) were detected to have HPgV recombinant sequences. Our results also revealed that while male patients shared the viral strains with other patients, viral strains from the female patients had restricted dispersal. Taken together, the present study revealed that multiple infections with divergent HPgV viral strains may have caused within-host genetic recombination, predominantly in male patients, and therefore, could be the major driver in shaping genetic diversity of HPgV.

  1. Genetic diversity and distribution patterns of host insects of Caterpillar Fungus Ophiocordyceps sinensis in the Qinghai-Tibet Plateau.

    PubMed

    Quan, Qing-Mei; Chen, Ling-Ling; Wang, Xi; Li, Shan; Yang, Xiao-Ling; Zhu, Yun-Guo; Wang, Mu; Cheng, Zhou

    2014-01-01

    The caterpillar fungus Ophiocordyceps sinensis is one of the most valuable medicinal fungi in the world, and it requires host insects in family Hepialidae (Lepidoptera) to complete its life cycle. However, the genetic diversity and phylogeographic structures of the host insects remain to be explored. We analyzed the genetic diversity and temporal and spatial distribution patterns of genetic variation of the host insects throughout the O. sinensis distribution. Abundant haplotype and nucleotide diversity mainly existed in the areas of Nyingchi, ShangriLa, and around the edge of the Qinghai-Tibet Plateau, where are considered as the diversity center or micro-refuges of the host insects of O. sinensis. However, there was little genetic variation among host insects from 72.1% of all populations, indicating that the host species composition might be relatively simple in large-scale O. sinensis populations. All host insects are monophyletic except for those from four O. sinensis populations around Qinghai Lake. Significant phylogeographic structure (NST>GST, P<0.05) was revealed for the monophyletic host insects, and the three major phylogenetic groups corresponded with specific geographical areas. The divergence of most host insects was estimated to have occurred at ca. 3.7 Ma, shortly before the rapid uplift of the QTP. The geographical distribution and star-like network of the haplotypes implied that most host insects were derived from the relicts of a once-widespread host that subsequently became fragmented. Neutrality tests, mismatch distribution analysis, and expansion time estimation confirmed that most host insects presented recent demographic expansions that began ca. 0.118 Ma in the late Pleistocene. Therefore, the genetic diversity and distribution of the present-day insects should be attributed to effects of the Qinghai-Tibet Plateau uplift and glacial advance/retreat cycles during the Quaternary ice age. These results provide valuable information to guide

  2. Host Genetic Control of the Microbiome in Humans and Maise or Relating Host Genetic Variation to the Microbiome (2011 JGI User Meeting)

    SciTech Connect

    Ley, Ruth

    2011-03-23

    The U.S. Department of Energy Joint Genome Institute (JGI) invited scientists interested in the application of genomics to bioenergy and environmental issues, as well as all current and prospective users and collaborators, to attend the annual DOE JGI Genomics of Energy & Environment Meeting held March 22-24, 2011 in Walnut Creek, Calif. The emphasis of this meeting was on the genomics of renewable energy strategies, carbon cycling, environmental gene discovery, and engineering of fuel-producing organisms. The meeting features presentations by leading scientists advancing these topics. Ruth Ley of Cornell University gives a presentation on "Relating Host Genetic Variation to the Microbiome" at the 6th annual Genomics of Energy & Environment Meeting on March 23, 2011.

  3. Host Genetic Control of the Microbiome in Humans and Maise or Relating Host Genetic Variation to the Microbiome (2011 JGI User Meeting)

    ScienceCinema

    Ley, Ruth [Cornell University

    2016-07-12

    The U.S. Department of Energy Joint Genome Institute (JGI) invited scientists interested in the application of genomics to bioenergy and environmental issues, as well as all current and prospective users and collaborators, to attend the annual DOE JGI Genomics of Energy & Environment Meeting held March 22-24, 2011 in Walnut Creek, Calif. The emphasis of this meeting was on the genomics of renewable energy strategies, carbon cycling, environmental gene discovery, and engineering of fuel-producing organisms. The meeting features presentations by leading scientists advancing these topics. Ruth Ley of Cornell University gives a presentation on "Relating Host Genetic Variation to the Microbiome" at the 6th annual Genomics of Energy & Environment Meeting on March 23, 2011.

  4. Host plant use drives genetic differentiation in syntopic populations of Maculinea alcon

    PubMed Central

    Fürst, Matthias A.

    2016-01-01

    The rare socially parasitic butterfly Maculinea alcon occurs in two forms, which are characteristic of hygric or xeric habitats and which exploit different host plants and host ants. The status of these two forms has been the subject of considerable controversy. Populations of the two forms are usually spatially distinct, but at Răscruci in Romania both forms occur on the same site (syntopically). We examined the genetic differentiation between the two forms using eight microsatellite markers, and compared with a nearby hygric site, Şardu. Our results showed that while the two forms are strongly differentiated at Răscruci, it is the xeric form there that is most similar to the hygric form at Şardu, and Bayesian clustering algorithms suggest that these two populations have exchanged genes relatively recently. We found strong evidence for population substructuring, caused by high within host ant nest relatedness, indicating very limited dispersal of most ovipositing females, but not association with particular host ant species. Our results are consistent with the results of larger scale phylogeographic studies that suggest that the two forms represent local ecotypes specialising on different host plants, each with a distinct flowering phenology, providing a temporal rather than spatial barrier to gene flow. PMID:27069804

  5. Accidental genetic engineers: horizontal sequence transfer from parasitoid wasps to their Lepidopteran hosts.

    PubMed

    Schneider, Sean E; Thomas, James H

    2014-01-01

    We show here that 105 regions in two Lepidoptera genomes appear to derive from horizontally transferred wasp DNA. We experimentally verified the presence of two of these sequences in a diverse set of silkworm (Bombyx mori) genomes. We hypothesize that these horizontal transfers are made possible by the unusual strategy many parasitoid wasps employ of injecting hosts with endosymbiotic polydnaviruses to minimize the host's defense response. Because these virus-like particles deliver wasp DNA to the cells of the host, there has been much interest in whether genetic information can be permanently transferred from the wasp to the host. Two transferred sequences code for a BEN domain, known to be associated with polydnaviruses and transcriptional regulation. These findings represent the first documented cases of horizontal transfer of genes between two organisms by a polydnavirus. This presents an interesting evolutionary paradigm in which host species can acquire new sequences from parasitoid wasps that attack them. Hymenoptera and Lepidoptera diverged ∼300 MYA, making this type of event a source of novel sequences for recipient species. Unlike many other cases of horizontal transfer between two eukaryote species, these sequence transfers can be explained without the need to invoke the sequences 'hitchhiking' on a third organism (e.g. retrovirus) capable of independent reproduction. The cellular machinery necessary for the transfer is contained entirely in the wasp genome. The work presented here is the first such discovery of what is likely to be a broader phenomenon among species affected by these wasps.

  6. Population Genetics of Nosema apis and Nosema ceranae: One Host (Apis mellifera) and Two Different Histories.

    PubMed

    Maside, Xulio; Gómez-Moracho, Tamara; Jara, Laura; Martín-Hernández, Raquel; De la Rúa, Pilar; Higes, Mariano; Bartolomé, Carolina

    2015-01-01

    Two microsporidians are known to infect honey bees: Nosema apis and Nosema ceranae. Whereas population genetics data for the latter have been released in the last few years, such information is still missing for N. apis. Here we analyze the patterns of nucleotide polymorphism at three single-copy loci (PTP2, PTP3 and RPB1) in a collection of Apis mellifera isolates from all over the world, naturally infected either with N. apis (N = 22) or N. ceranae (N = 23), to provide new insights into the genetic diversity, demography and evolution of N. apis, as well as to compare them with evidence from N. ceranae. Neutral variation in N. apis and N. ceranae is of the order of 1%. This amount of diversity suggests that there is no substantial differentiation between the genetic content of the two nuclei present in these parasites, and evidence for genetic recombination provides a putative mechanism for the flow of genetic information between chromosomes. The analysis of the frequency spectrum of neutral variants reveals a significant surplus of low frequency variants, particularly in N. ceranae, and suggests that the populations of the two pathogens are not in mutation-drift equilibrium and that they have experienced a population expansion. Most of the variation in both species occurs within honey bee colonies (between 62%-90% of the total genetic variance), although in N. apis there is evidence for differentiation between parasites isolated from distinct A. mellifera lineages (20%-34% of the total variance), specifically between those collected from lineages A and C (or M). This scenario is consistent with a long-term host-parasite relationship and contrasts with the lack of differentiation observed among host-lineages in N. ceranae (< 4% of the variance), which suggests that the spread of this emergent pathogen throughout the A. mellifera worldwide population is a recent event.

  7. Population Genetics of Nosema apis and Nosema ceranae: One Host (Apis mellifera) and Two Different Histories

    PubMed Central

    Maside, Xulio; Gómez-Moracho, Tamara; Jara, Laura; Martín-Hernández, Raquel; De la Rúa, Pilar; Higes, Mariano; Bartolomé, Carolina

    2015-01-01

    Two microsporidians are known to infect honey bees: Nosema apis and Nosema ceranae. Whereas population genetics data for the latter have been released in the last few years, such information is still missing for N. apis. Here we analyze the patterns of nucleotide polymorphism at three single-copy loci (PTP2, PTP3 and RPB1) in a collection of Apis mellifera isolates from all over the world, naturally infected either with N. apis (N = 22) or N. ceranae (N = 23), to provide new insights into the genetic diversity, demography and evolution of N. apis, as well as to compare them with evidence from N. ceranae. Neutral variation in N. apis and N. ceranae is of the order of 1%. This amount of diversity suggests that there is no substantial differentiation between the genetic content of the two nuclei present in these parasites, and evidence for genetic recombination provides a putative mechanism for the flow of genetic information between chromosomes. The analysis of the frequency spectrum of neutral variants reveals a significant surplus of low frequency variants, particularly in N. ceranae, and suggests that the populations of the two pathogens are not in mutation-drift equilibrium and that they have experienced a population expansion. Most of the variation in both species occurs within honey bee colonies (between 62%-90% of the total genetic variance), although in N. apis there is evidence for differentiation between parasites isolated from distinct A. mellifera lineages (20%-34% of the total variance), specifically between those collected from lineages A and C (or M). This scenario is consistent with a long-term host-parasite relationship and contrasts with the lack of differentiation observed among host-lineages in N. ceranae (< 4% of the variance), which suggests that the spread of this emergent pathogen throughout the A. mellifera worldwide population is a recent event. PMID:26720131

  8. The cause of parasitic infection in natural populations of Daphnia (Crustacea: Cladocera): the role of host genetics.

    PubMed Central

    Little, T J; Ebert, D

    2000-01-01

    Disease patterns in nature may be determined by genetic variation for resistance or by factors, genetic or environmental, which influence the host-parasite encounter rate. Elucidating the cause of natural infection patterns has been a major pursuit of parasitologists, but it also matters for evolutionary biologists because host resistance genes must influence the expression of disease if parasite-mediated selection is to occur. We used a model system in order to disentangle the strict genetic component from other causes of infection in the wild. Using the crustacean Daphnia magna and its sterilizing bacterial parasite Pasteuria ramosa, we tested whether genetic variation for resistance, as determined under controlled conditions, accounted for the distribution of infections within natural populations. Specifically, we compared whether the clonally produced great-granddaughters of those individuals that were infected in field samples (but were subsequently 'cured' with antibiotics) were more susceptible than were the great-granddaughters of those individuals that were healthy in field samples. High doses of parasite spores led to increased infection in all four study populations, indicating the importance of encounter rate. Host genetics appeared to be irrelevant to natural infection patterns in one population. However, in three other populations hosts that were healthy in the field had greater genetic-based resistance than hosts that were infected in the field, unambiguously showing the effect of host genetic factors on the expression of disease in the wild. PMID:11416906

  9. Comparative Genome Sequencing Reveals Within-Host Genetic Changes in Neisseria meningitidis during Invasive Disease

    PubMed Central

    Klughammer, Johanna; Dittrich, Marcus; Blom, Jochen; Mitesser, Vera; Vogel, Ulrich; Frosch, Matthias; Goesmann, Alexander; Müller, Tobias

    2017-01-01

    Some members of the physiological human microbiome occasionally cause life-threatening disease even in immunocompetent individuals. A prime example of such a commensal pathogen is Neisseria meningitidis, which normally resides in the human nasopharynx but is also a leading cause of sepsis and epidemic meningitis. Using N. meningitidis as model organism, we tested the hypothesis that virulence of commensal pathogens is a consequence of within host evolution and selection of invasive variants due to mutations at contingency genes, a mechanism called phase variation. In line with the hypothesis that phase variation evolved as an adaptation to colonize diverse hosts, computational comparisons of all 27 to date completely sequenced and annotated meningococcal genomes retrieved from public databases showed that contingency genes are indeed enriched for genes involved in host interactions. To assess within-host genetic changes in meningococci, we further used ultra-deep whole-genome sequencing of throat-blood strain pairs isolated from four patients suffering from invasive meningococcal disease. We detected up to three mutations per strain pair, affecting predominantly contingency genes involved in type IV pilus biogenesis. However, there was not a single (set) of mutation(s) that could invariably be found in all four pairs of strains. Phenotypic assays further showed that these genetic changes were generally not associated with increased serum resistance, higher fitness in human blood ex vivo or differences in the interaction with human epithelial and endothelial cells in vitro. In conclusion, we hypothesize that virulence of meningococci results from accidental emergence of invasive variants during carriage and without within host evolution of invasive phenotypes during disease progression in vivo. PMID:28081260

  10. Hosts, distribution and genetic divergence (16S rDNA) of Amblyomma dubitatum (Acari: Ixodidae).

    PubMed

    Nava, Santiago; Venzal, José M; Labruna, Marcelo B; Mastropaolo, Mariano; González, Enrique M; Mangold, Atilio J; Guglielmone, Alberto A

    2010-08-01

    We supply information about hosts and distribution of Amblyomma dubitatum. In addition, we carry out an analysis of genetic divergence among specimens of A. dubitatum from different localities and with respect to other Neotropical Amblyomma species, using sequences of 16S rDNA gene. Although specimens of A. dubitatum were collected on several mammal species as cattle horse, Tapirus terrestris, Mazama gouazoubira, Tayassu pecari, Sus scrofa, Cerdocyon thous, Myocastor coypus, Allouata caraya, Glossophaga soricina and man, most records of immature and adult stages of A. dubitatum were made on Hydrochoerus hydrochaeris, making this rodent the principal host for all parasitic stages of this ticks. Cricetidae rodents (Lundomys molitor, Scapteromys tumidus), opossums (Didelphis albiventris) and vizcacha (Lagostomus maximus) also were recorded as hosts for immature stages. All findings of A. dubitatum correspond to localities of Argentina, Brazil, Paraguay and Uruguay, and they were concentrated in the Biogeographical provinces of Pampa, Chaco, Cerrado, Brazilian Atlantic Forest, Parana Forest and Araucaria angustifolia Forest. The distribution of A. dubitatum is narrower than that of its principal host, therefore environmental variables rather than hosts determine the distributional ranges of this tick. The intraspecific genetic divergence among 16S rDNA sequences of A. dubitatum ticks collected in different localities from Argentina, Brazil and Uruguay was in all cases lower than 0.8%, whereas the differences with the remaining Amblyomma species included in the analysis were always bigger than 6.8%. Thus, the taxonomic status of A. dubitatum along its distribution appears to be certain at the specific level.

  11. Genetic and behavioral discrimination of host plant populations of the leafbeetle, Psylliodes chalcomera, for biological control of yellow starthistle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molecular genetic techniques clearly distinguish three separate populations within the flea beetle "species" Psylliodes chalcomera that are associated with three different host plants (yellow starthistle, Scotch thistle and musk thistle). Preliminary studies have not revealed any reliable morpholog...

  12. Allopatric genetic origins for sympatric host-plant shifts and race formation in Rhagoletis

    PubMed Central

    Feder, Jeffrey L.; Berlocher, Stewart H.; Roethele, Joseph B.; Dambroski, Hattie; Smith, James J.; Perry, William L.; Gavrilovic, Vesna; Filchak, Kenneth E.; Rull, Juan; Aluja, Martin

    2003-01-01

    Tephritid fruit flies belonging to the Rhagoletis pomonella sibling species complex are controversial because they have been proposed to diverge in sympatry (in the absence of geographic isolation) by shifting and adapting to new host plants. Here, we report evidence suggesting a surprising source of genetic variation contributing to sympatric host shifts for these flies. From DNA sequence data for three nuclear loci and mtDNA, we infer that an ancestral, hawthorn-infesting R. pomonella population became geographically subdivided into Mexican and North American isolates ≈1.57 million years ago. Episodes of gene flow from Mexico subsequently infused the North American population with inversion polymorphism affecting key diapause traits, forming adaptive clines. Sometime later (perhaps ±1 million years), diapause variation in the latitudinal clines appears to have aided North American flies in adapting to a variety of plants with differing fruiting times, helping to spawn several new taxa. Thus, important raw genetic material facilitating the adaptive radiation of R. pomonella originated in a different time and place than the proximate ecological host shifts triggering sympatric divergence. PMID:12928500

  13. Environmental conditions and host genotype direct genetic diversity of Venturia ditricha, a fungal endophyte of birch trees.

    PubMed

    Ahlholm, Jouni U; Helander, Marjo; Henriksson, Janne; Metzler, Mary; Saikkonen, Kari

    2002-08-01

    We investigated whether genetic variation of a common foliar endophyte of birch trees, Venturia ditricha, is affected by environmental conditions or host genotype. Fungal samples were collected from 10 half-sibling families of mountain birch (Betula pubescens ssp. czerepanovii) grown in two environmental conditions with different daily average temperatures: a forested river valley and an adjacent open tundra (altitudinal difference 180 m). Genetic analysis of V. ditricha isolates was done using random amplified microsatellite polymerase chain reaction. We found that host genotypes, along with prevailing environmental conditions, influence the probability of infection by particular endophyte genotypes. The most susceptible host genotypes were highly infected with genetically similar endophyte genotypes, whereas the most resistant trees were poorly infected and they were infected by genetically dissimilar endophytes. Our results also showed environment-host genotype interactions, suggesting that the susceptibility of the host to a particular endophyte genotype may change in natural environments when environmental conditions are changed. It appears that a particular endophyte genotype needs to find the right host genotype for a successful infection. There are many host genotypes in natural stands; this means, from the point of view of the fungus, the environment is heterogeneous. Thus, under the influence of birch tree genotypes, genetically differentiated subgroups of the endophytic fungus may be formed in different environments.

  14. The genetic architecture of a complex ecological trait: host plant use in the specialist moth, HELIOTHIS SUBFLEXA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study of the genetic basis of ecological adaptation remains in its infancy, and most studies have focused on phenotypically simple traits. Host plant use by herbivorous insects is phenotypically complex. While research has illuminated the evolutionary determinants of host use, knowledge of its...

  15. Draft genome sequences of 53 genetically distinct isolates of Bordetella bronchiseptica representing 11 terrestrial and aquatic hosts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bordetella bronchiseptica infects a variety of mammalian and avian hosts. Here we report the genome sequences of 53 genetically distinct isolates, acquired from a broad range of terrestrial and aquatic animals. These data will greatly facilitate ongoing efforts to better understand evolution, host...

  16. Unexpected absence of genetic separation of a highly diverse population of hookworms from geographically isolated hosts.

    PubMed

    Haynes, Benjamin T; Marcus, Alan D; Higgins, Damien P; Gongora, Jaime; Gray, Rachael; Šlapeta, Jan

    2014-12-01

    The high natal site fidelity of endangered Australian sea lions (Neophoca cinerea) along the southern Australian coast suggests that their maternally transmitted parasitic species, such as hookworms, will have restricted potential for dispersal. If this is the case, we would expect to find a hookworm haplotype structure corresponding to that of the host mtDNA haplotype structure; that is, restricted among geographically separated colonies. In this study, we used a fragment of the cytochrome c oxidase I mitochondrial DNA (mtDNA) gene to investigate the diversity of hookworms (Uncinaria sanguinis) in N. cinerea to assess the importance of host distribution and ecology on the evolutionary history of the parasite. High haplotype (h=0.986) and nucleotide diversity (π=0.013) were seen, with 45 unique hookworm mtDNA haplotypes across N. cinerea colonies; with most of the variation (78%) arising from variability within hookworms from individual colonies. This is supported by the low genetic differentiation co-efficient (GST=0.007) and a high gene flow (Nm=35.25) indicating a high migration rate between the populations of hookworms. The haplotype network demonstrated no clear distribution and delineation of haplotypes according to geographical location. Our data rejects the vicariance hypothesis; that female host natal site fidelity and the transmammary route of infection restrict hookworm gene flow between N. cinerea populations and highlights the value of studies of parasite diversity and dispersal to challenge our understanding of parasite and host ecology.

  17. Prevalence, Genetic Diversity, and Host Range of Tectiviruses among Members of the Bacillus cereus Group

    PubMed Central

    Gillis, Annika

    2014-01-01

    GIL01, Bam35, GIL16, AP50, and Wip1 are tectiviruses preying on the Bacillus cereus group. Despite the significant contributions of phages in different biological processes, little is known about the dealings taking place between tectiviruses and their Gram-positive bacterial hosts. Therefore, this work focuses on characterizing the interactions between tectiviruses and the B. cereus group by assessing their occurrence and genetic diversity and evaluating their host range. To study the occurrence of tectiviruses in the B. cereus group, 2,000 isolates were evaluated using primers designed to be specific to two variable regions detected in previously described elements. PCR and propagation tests revealed that tectivirus-like elements occurred in less than 3% of the isolates. Regardless of this limited distribution, several novel tectiviruses were found, and partial DNA sequencing indicated that a greater diversity exists within the family Tectiviridae. Analyses of the selected variable regions, along with their host range, showed that tectiviruses in the B. cereus group can be clustered mainly into two different groups: the ones infecting B. anthracis and those isolated from other B. cereus group members. In order to address the host range of some novel tectiviruses, 120 strains were tested for sensitivity. The results showed that all the tested tectiviruses produced lysis in at least one B. cereus sensu lato strain. Moreover, no simple relationship between the infection patterns of the tectiviruses and their diversity was found. PMID:24795369

  18. Feature selection methods for identifying genetic determinants of host species in RNA viruses.

    PubMed

    Aguas, Ricardo; Ferguson, Neil M

    2013-01-01

    Despite environmental, social and ecological dependencies, emergence of zoonotic viruses in human populations is clearly also affected by genetic factors which determine cross-species transmission potential. RNA viruses pose an interesting case study given their mutation rates are orders of magnitude higher than any other pathogen--as reflected by the recent emergence of SARS and Influenza for example. Here, we show how feature selection techniques can be used to reliably classify viral sequences by host species, and to identify the crucial minority of host-specific sites in pathogen genomic data. The variability in alleles at those sites can be translated into prediction probabilities that a particular pathogen isolate is adapted to a given host. We illustrate the power of these methods by: 1) identifying the sites explaining SARS coronavirus differences between human, bat and palm civet samples; 2) showing how cross species jumps of rabies virus among bat populations can be readily identified; and 3) de novo identification of likely functional influenza host discriminant markers.

  19. Prevalence, genetic diversity, and host range of tectiviruses among members of the Bacillus cereus group.

    PubMed

    Gillis, Annika; Mahillon, Jacques

    2014-07-01

    GIL01, Bam35, GIL16, AP50, and Wip1 are tectiviruses preying on the Bacillus cereus group. Despite the significant contributions of phages in different biological processes, little is known about the dealings taking place between tectiviruses and their Gram-positive bacterial hosts. Therefore, this work focuses on characterizing the interactions between tectiviruses and the B. cereus group by assessing their occurrence and genetic diversity and evaluating their host range. To study the occurrence of tectiviruses in the B. cereus group, 2,000 isolates were evaluated using primers designed to be specific to two variable regions detected in previously described elements. PCR and propagation tests revealed that tectivirus-like elements occurred in less than 3% of the isolates. Regardless of this limited distribution, several novel tectiviruses were found, and partial DNA sequencing indicated that a greater diversity exists within the family Tectiviridae. Analyses of the selected variable regions, along with their host range, showed that tectiviruses in the B. cereus group can be clustered mainly into two different groups: the ones infecting B. anthracis and those isolated from other B. cereus group members. In order to address the host range of some novel tectiviruses, 120 strains were tested for sensitivity. The results showed that all the tested tectiviruses produced lysis in at least one B. cereus sensu lato strain. Moreover, no simple relationship between the infection patterns of the tectiviruses and their diversity was found.

  20. Natural host relationships and genetic diversity of Whitewater Arroyo virus in southern Texas.

    PubMed

    Fulhorst, Charles F; Milazzo, Mary Louise; Carroll, Darin S; Charrel, Remi N; Bradley, Robert D

    2002-07-01

    The purpose of this study was to refine our knowledge of the natural host relationships of Whitewater Arroyo (WWA) virus. Two hundred eight rodents, representing nine species, were captured in July 1999 on the Chaparral Wildlife Management Area in southern Texas and tested for evidence of arenavirus infection. Antibody to an arenavirus was found in seven (21.9%) of 32 southern plains woodrats (Neotoma micropus) and none of 168 other rodents. Infectious WWA virus was isolated from four antibody-positive southern plains woodrats, one of 25 antibody-negative southern plains woodrats, and none of 176 other rodents. Collectively, the results indicate that the southern plains woodrat is a principal host of WWA virus in southern Texas. Analyses of viral gene sequence data revealed substantial genetic diversity among WWA virus strains isolated from the woodrats, suggesting that multiple variants of the virus can coexist in a single woodrat species in a small geographic area.

  1. Genetic diversity, temporal dynamics, and host specificity in blood parasites of passerines in north China.

    PubMed

    Huang, Xi; Dong, Lu; Zhang, Chenglin; Zhang, Yanyun

    2015-12-01

    Avian blood parasites have been preliminarily studied in East Asia, but no data are available from long-term monitoring. The aim of this study was to evaluate the prevalence, genetic diversity, and temporal dynamics of Plasmodium, Haemoproteus, and Leucocytozoon in two passerine communities (one forest and one urban) in north China from 2008 to 2013, as well as the association between infected lineages and host specificities. Out of 633 birds from 40 species, 157 individuals (24.8 %) were infected; overall prevalence was 26.7 % and 16.8 % in two sites, respectively. The dominant avian blood parasite genus in the forest park changed yearly between Plasmodium and Haemoproteus, while the Leucocytozoon maintained a low infection level. Forty-four haplotypes were identified by sequencing a 432-bp fragment of the cytochrome b (cyt b) gene; more than 70 % were novel (six Plasmodium lineages, 16 Haemoproteus lineages, and nine Leucocytozoon lineages). Based on our data gathered over consecutive years, we found that the highly observed lineages of Haemoproteus showed higher host diversities than those of Plasmodium, and the most infected lineage EMEL01 (100 % identity with SGS1) take on the highest host diversity but low temporal diversity of the two genera, implying that this lineage infected a great diversity of species in certain years, but maintained a lower infection level or even disappeared in other years. The results suggest that genetic diversity of avian blood parasites in East Asia is high and provides scope for further research. In addition, compared with overall analysis, yearly prevalence monitoring is important in uncovering the temporal dynamic and host specificity variations over time.

  2. History, geography and host use shape genomewide patterns of genetic variation in the redheaded pine sawfly (Neodiprion lecontei).

    PubMed

    Bagley, Robin K; Sousa, Vitor C; Niemiller, Matthew L; Linnen, Catherine R

    2017-02-01

    Divergent host use has long been suspected to drive population differentiation and speciation in plant-feeding insects. Evaluating the contribution of divergent host use to genetic differentiation can be difficult, however, as dispersal limitation and population structure may also influence patterns of genetic variation. In this study, we use double-digest restriction-associated DNA (ddRAD) sequencing to test the hypothesis that divergent host use contributes to genetic differentiation among populations of the redheaded pine sawfly (Neodiprion lecontei), a widespread pest that uses multiple Pinus hosts throughout its range in eastern North America. Because this species has a broad range and specializes on host plants known to have migrated extensively during the Pleistocene, we first assess overall genetic structure using model-based and model-free clustering methods and identify three geographically distinct genetic clusters. Next, using a composite-likelihood approach based on the site frequency spectrum and a novel strategy for maximizing the utility of linked RAD markers, we infer the population topology and date divergence to the Pleistocene. Based on existing knowledge of Pinus refugia, estimated demographic parameters and patterns of diversity among sawfly populations, we propose a Pleistocene divergence scenario for N. lecontei. Finally, using Mantel and partial Mantel tests, we identify a significant relationship between genetic distance and geography in all clusters, and between genetic distance and host use in two of three clusters. Overall, our results indicate that Pleistocene isolation, dispersal limitation and ecological divergence all contribute to genomewide differentiation in this species and support the hypothesis that host use is a common driver of population divergence in host-specialized insects.

  3. Genetics of Graft-versus-Host Disease: The Major Histocompatibility Complex

    PubMed Central

    Petersdorf, Effie W.

    2013-01-01

    Graft-versus-host disease (GVHD) is a potentially life-threatening complication of allogeneic hematopoietic cell transplantation. Many genes are presumed to be involved in GVHD, but the best characterized genetic system is that of the human major histocompatibility complex (MHC) located on chromosome 6. Among the hundreds of genes located within the MHC region, the best known and characterized are the classical HLA genes, HLA-A, C, B, DRB1, DQB1, and DPB1. They play a fundamental role in T cell immune responses, and HLA-A, C, and B also function as ligands for the natural killer cell immunoglobulin-like receptors involved in innate immunity. This review highlights the state-of-the art in the field of histocompatibility and immunogenetics of the MHC with respect to genetic risk factors for GVHD. PMID:23182478

  4. Genetic uniformity of Echinococcus multilocularis collected from different intermediate host species in Hokkaido, Japan.

    PubMed

    Okamoto, Munehiro; Oku, Yuzaburo; Kurosawa, Tsutomu; Kamiya, Masao

    2007-02-01

    DNA from several isolates of Taenia taeniaeformis and Echinococcus multilocularis were digested with restriction enzymes and hybridized with digoxigenated oligonucleotide probe (CAC)5. Within the six wild isolates of Taenia taeniaeformis from Norway rats in Hokkaido, although several bands were common among isolates, fingerprinting patterns were specific to each isolate. In the case of E. multilocularis, regardless of hosts from which each isolate has been isolated, the five isolates collected from Hokkaido, showed the same fingerprinting pattern. These results indicate that there was very little genetic difference among these isolates. Although the fingerprinting pattern of E. multilocularis from St. Lawrence Is. was similar to that of the Hokkaido isolates, some bands were different from those in the Hokkaido isolates. Echinococcus multilocularis in Hokkaido seems to be closely-related genetically to that from St. Lawrence Is.

  5. Sympatric genetic differentiation of a generalist pathogenic fungus, Botrytis cinerea, on two different host plants, grapevine and bramble.

    PubMed

    Fournier, E; Giraud, T

    2008-01-01

    Prime candidates for sympatric ecological divergence include parasites that differentiate via host shifts, because different host species exert strong disruptive selection and because both hosts and parasites are continually co-evolving. Sympatric divergence may be fostered even more strongly in phytopathogenic fungi, in particular those where sex must occur on the host, which allows adaptation alone to restrict gene flow between populations developing on different hosts. We sampled populations of Botrytis cinerea, a generalist ascomycete fungus, on sympatric grapes and brambles in six regions in France. Microsatellite data were analyzed using standard population genetics, a population graph analysis and a Bayesian approach. In addition to confirming that B. cinerea reproduces sexually, our results showed that the fungal populations on the two hosts were significantly differentiated, indicating restricted gene flow, even in sympatry. In contrast, only weak geographical differentiation could be detected. These results support the possibility of sympatric divergence associated with host use in generalist parasites.

  6. Morphology and its underlying genetic regulation impact the interaction between Cryptococcus neoformans and its hosts.

    PubMed

    Lin, Jianfeng; Idnurm, Alexander; Lin, Xiaorong

    2015-06-01

    Cryptococcus neoformans is a fungus that causes the majority of fatal cryptococcal meningitis cases worldwide. This pathogen is capable of assuming different morphotypes: yeast, pseudohypha, and hypha. The yeast form is the most common cell type observed clinically. The hyphal and pseudohyphal forms are rarely observed in the clinical setting and are considered attenuated in virulence. However, as a ubiquitous environmental pathogen, Cryptococcus interacts with various organisms, and it is known to be parasitic to different hosts. Capitalizing on recent discoveries, morphogenesis regulators were manipulated to examine the impact of cell shape on the cryptococcal interaction with three different host systems: the soil amoeba Acanthamoeba castellanii (a protist), the greater wax moth Galleria mellonella (an insect), and the murine macrophage cell line J774A.1 (mammalian cells). The regulation of Ace2 and morphogenesis (RAM) pathway is a highly conserved pathway among eukaryotes that regulates cytokinesis. Disruption of any of five RAM components in Cryptococcus renders cells constitutively in the pseudohyphal form. The transcription factor Znf2 is the master activator of the yeast to hyphal transition. Deletion of ZNF2 locks cells in the yeast form, while overexpression of this regulator drives hyphal growth. Genetic epistasis analyses indicate that the RAM and the Znf2 pathways regulate distinct aspects of cryptococcal morphogenesis and independently of each other. These investigations using the Cryptococcus RAM and ZNF2 mutants indicate that cell shape, cell size, and likely cell surface properties weigh differently on the outcome of cryptococcal interactions with different hosts. Thus, certain traits evolved in Cryptococcus that are beneficial within one host might be detrimental when a different host is encountered.

  7. Susceptibility of carnivore hosts to strains of canine distemper virus from distinct genetic lineages.

    PubMed

    Nikolin, Veljko M; Wibbelt, Gudrun; Michler, Frank-Uwe F; Wolf, Peter; East, Marion L

    2012-04-23

    Using the complete haemagglutinin (HA) gene and partial phosphoprotein (P) gene we investigated the genotype of canine distemper virus (CDV) strains recovered from two wildlife species in Mecklenburg-Vorpommern, Germany. Phylogenetic analyses demonstrated significant differences between the strains from raccoons Procyon lotor (family Procyonidae) obtained in 2007 and strains from red foxes Vulpes vulpes (family Canidae) obtained in 2008. The raccoon strains belonged to the CDV European wildlife lineage whereas the red fox strains belonged to the CDV Europe lineage. We combined our genetic sequence data with published data from 138 CDV stains worldwide to investigate the proposed importance of amino acid substitutions in the SLAM binding region of the CDV HA protein at position 530 (G/E to R/D/N) and 549 (Y to H) to the spread of domestic dog-adapted CDV strains to other carnivores. We found no evidence that amino acid 530 was strongly affected by host species. Rather, site 530 was conserved within CDV lineages, regardless of host species. Contrary to expectation, strains from non-dog hosts did not exhibit a bias towards the predicted substitution Y549H. Wild canid hosts were more frequently infected by strains with 549Y, a pattern similar to domestic dogs. Non-canid strains showed no significant bias towards either H or Y at site 549, although there was a trend towards 549H. Significant differences between the prevalence of 549Y and 549H in wild canid strains and non-canid strains suggests a degree of virus adaptation to these categories of host.

  8. [Molecular-genetic analysis of wheat (T. aestivum L.) genome with introgression of Ae. cylindrica Host genetic elements].

    PubMed

    Galaev, A V; Sivolap, Iu M

    2005-01-01

    Wheat-aegilops hybrid plants Triticum aestivum L. (2n = 42) x Aegilops cylindrica Host (2n = 28) were investigated with using microsatellite markers. In two BC1F9 lines some genome modifications connected with losing DNA fragments of initial variety or appearing of Aegilops genome elements were detected. In some investigated hybrids new amplicons lacking in parental plants were found. Substitution of wheat chromosomes for aegilops chromosomes was not revealed. Analysis of microsatellite loci in BC2F5 plants showed stable introgression of aegilops genetic elements into wheat; elimination of some transferred aegilops DNA fragments in the course of backcrossing; decreasing size of introgressive elements after backcrossing. Introgressive lines were classified according to genome changes.

  9. Genetic diversity, host range, and distribution of tomato yellow leaf curl virus in Iran.

    PubMed

    Shirazi, M; Mozafari, J; Rakhshandehroo, F; Shams-Bakhsh, M

    2014-01-01

    Tomato yellow leaf curl virus (TYLCV) is considered one of the most important tomato pathogens in tropical and subtropical regions including Iran. During the years 2007 to 2009, a total number of 510 symptomatic and asymptomatic vegetable, ornamental and weed samples were collected from fields and greenhouses in ten provinces of Iran. Symptoms included stunting, yellowing, leaf curl and flower senescence. PCR with specific primers showed TYLCV infection in 184 samples (36%) such as cucumber, pepper, tomato and several weeds from seven provinces. Based on the geographical origin, host range and symptoms, twenty three representative isolates were selected for phylogenetic analysis. An amplicon with a size about 608 base pair (bp) comprising partial sequence of the coat (CP) and movement protein (MP) coding regions of the viral genome was sequenced and compared with the corresponding selected sequences available in GenBank for Iran and worldwide. Phylogenetic analyses on the basis of the nucleotide sequences indicated two geographically separated clades. Isolates collected from Hormozgan, Khuzestan and Kerman provinces were grouped together with other Iranian isolates including TYLCV-Ir2, TYLCV-Kahnooj, and an isolate from Oman. It was also revealed that isolates collected from Boushehr, Fars, Tehran, and Isfahan placed close to the Iranian isolate TYLCV-Abadeh and isolates from Israel and Egypt. No correlation was found between the genetic variation and the host species, but selected Iranian isolates were grouped on the basis of the geographical origins. Results of this study indicated a high genetic diversity among Iranian TYLCV isolates.

  10. Inter Individual Variations of the Fish Skin Microbiota: Host Genetics Basis of Mutualism?

    PubMed Central

    Boutin, Sébastien; Sauvage, Christopher; Bernatchez, Louis; Audet, Céline; Derome, Nicolas

    2014-01-01

    The commensal microbiota of fish skin is suspected to provide a protection against opportunist infections. The skin of fish harbors a complex and diverse microbiota that closely interacts with the surrounding water microbial communities. Up to now there is no clear evidence as to whether the host regulates the recruitment of environmental bacteria to build a specific skin microbiota. To address this question, we detected Quantitative Trait Loci (QTL) associated with the abundance of specific skin microbiota bacterial strains in brook charr (Salvelinus fontinalis), combining 16S RNA tagged-amplicon 454 pyrosequencing with genetic linkage analysis. Skin microbiota analysis revealed high inter-individual variation among 86 F2 fish progeny based upon the relative abundance of bacterial operational taxonomic units (OTUs). Out of those OTUs, the pathogenic strain Flavobacterium psychrophilum and the non-pathogenic strain Methylobacterium rhodesianum explained the majority of inter-individual distances. Furthermore, a strong negative correlation was found between Flavobacterium and Methylobacterium, suggesting a mutually competitive relationship. Finally, after considering a total of 266 markers, genetic linkage analysis highlighted three major QTL associated with the abundance of Lysobacter, Rheinheimera and Methylobacterium. All these three genera are known for their beneficial antibacterial activity. Overall, our results provide evidence that host genotype may regulate the abundance of specific genera among their surface microbiota. They also indicate that Lysobacter, Rheinheimera and Methylobacterium are potentially important genera in providing protection against pathogens. PMID:25068850

  11. Effect of host plant chemistry on genetic differentiation and reduction of gene flow among Anastrepha fraterculus (Diptera: Tephritidae) populations exploiting sympatric, synchronic hosts.

    PubMed

    Oroño, Luis; Paulin, Laura; Alberti, Andrea C; Hilal, Mirna; Ovruski, Sergio; Vilardi, Juan C; Rull, Juan; Aluja, Martin

    2013-08-01

    Herbivore host specialization includes changes in behavior, driven by locally induced adaptations to specific plants. These adaptations often result in sexual isolation that can be gauged through detection of reduced gene flow between host associated populations. Hypothetically, reduced gene flow can be mediated both by differential response to specific plant kairomones and by the influence of larval diet on some adult traits such as pheromone composition. These hypotheses could serve as a model to explain rapid radiation of phytophagous tephritid fruit flies, a group that includes several complexes of cryptic species. The South American Fruit Fly Anastrepha fraterculus (Wiedemann) is a complex of at least seven cryptic species among which pheromone mediated sexual isolation resulted in rapid differentiation. Cryptic species also exhibit differences in host affiliation. In search of a model explaining rapid radiation in this group, we studied host plant chemical composition and genetic structure of three host associated sympatric populations of A. fraterculus. Chemical composition among host plant fruit varied widely both for nutrient and potentially toxic secondary metabolite content. Adaptation to plant chemistry appears to have produced population differentiation. We found host mediated differentiation to be stronger between populations exploiting sympatric synchronic hosts differing in chemical composition, than between populations that exploit hosts that fruit in succession. Gene flow among such host associated populations was extremely low. We propose as a working hypothesis for future research, that for those differences to persist over time, isolating mechanisms such as male produced sex pheromones and female preferences resulting from adaptation to different larval diets should evolve.

  12. Interplay of host microbiota, genetic perturbations, and inflammation promotes local development of intestinal neoplasms in mice.

    PubMed

    Bongers, Gerold; Pacer, Michelle E; Geraldino, Thais H; Chen, Lili; He, Zhengxiang; Hashimoto, Daigo; Furtado, Glaucia C; Ochando, Jordi; Kelley, Kevin A; Clemente, Jose C; Merad, Miriam; van Bakel, Harm; Lira, Sergio A

    2014-03-10

    The preferential localization of some neoplasms, such as serrated polyps (SPs), in specific areas of the intestine suggests that nongenetic factors may be important for their development. To test this hypothesis, we took advantage of transgenic mice that expressed HB-EGF throughout the intestine but developed SPs only in the cecum. Here we show that a host-specific microbiome was associated with SPs and that alterations of the microbiota induced by antibiotic treatment or by embryo transfer rederivation markedly inhibited the formation of SPs in the cecum. Mechanistically, development of SPs was associated with a local decrease in epithelial barrier function, bacterial invasion, production of antimicrobials, and increased expression of several inflammatory factors such as IL-17, Cxcl2, Tnf-α, and IL-1. Increased numbers of neutrophils were found within the SPs, and their depletion significantly reduced polyp growth. Together these results indicate that nongenetic factors contribute to the development of SPs and suggest that the development of these intestinal neoplasms in the cecum is driven by the interplay between genetic changes in the host, an inflammatory response, and a host-specific microbiota.

  13. Interplay of host microbiota, genetic perturbations, and inflammation promotes local development of intestinal neoplasms in mice

    PubMed Central

    Bongers, Gerold; Pacer, Michelle E.; Geraldino, Thais H.; Chen, Lili; He, Zhengxiang; Hashimoto, Daigo; Furtado, Glaucia C.; Ochando, Jordi; Kelley, Kevin A.; Clemente, Jose C.; Merad, Miriam; van Bakel, Harm

    2014-01-01

    The preferential localization of some neoplasms, such as serrated polyps (SPs), in specific areas of the intestine suggests that nongenetic factors may be important for their development. To test this hypothesis, we took advantage of transgenic mice that expressed HB-EGF throughout the intestine but developed SPs only in the cecum. Here we show that a host-specific microbiome was associated with SPs and that alterations of the microbiota induced by antibiotic treatment or by embryo transfer rederivation markedly inhibited the formation of SPs in the cecum. Mechanistically, development of SPs was associated with a local decrease in epithelial barrier function, bacterial invasion, production of antimicrobials, and increased expression of several inflammatory factors such as IL-17, Cxcl2, Tnf-α, and IL-1. Increased numbers of neutrophils were found within the SPs, and their depletion significantly reduced polyp growth. Together these results indicate that nongenetic factors contribute to the development of SPs and suggest that the development of these intestinal neoplasms in the cecum is driven by the interplay between genetic changes in the host, an inflammatory response, and a host-specific microbiota. PMID:24590763

  14. Implications of host genetic variation on the risk and prevalence of infectious diseases transmitted through the environment.

    PubMed

    Doeschl-Wilson, Andrea B; Davidson, R; Conington, J; Roughsedge, T; Hutchings, M R; Villanueva, B

    2011-07-01

    Previous studies have shown that host genetic heterogeneity in the response to infectious challenge can affect the emergence risk and the severity of diseases transmitted through direct contact between individuals. However, there is substantial uncertainty about the degree and direction of influence owing to different definitions of genetic variation, most of which are not in line with the current understanding of the genetic architecture of disease traits. Also, the relevance of previous results for diseases transmitted through environmental sources is unclear. In this article a compartmental genetic-epidemiological model was developed to quantify the impact of host genetic diversity on epidemiological characteristics of diseases transmitted through a contaminated environment. The model was parameterized for footrot in sheep. Genetic variation was defined through continuous distributions with varying shape and degree of dispersion for different disease traits. The model predicts a strong impact of genetic heterogeneity on the disease risk and its progression and severity, as well as on observable host phenotypes, when dispersion in key epidemiological parameters is high. The impact of host variation depends on the disease trait for which variation occurs and on environmental conditions affecting pathogen survival. In particular, compared to homogeneous populations with the same average susceptibility, disease risk and severity are substantially higher in populations containing a large proportion of highly susceptible individuals, and the differences are strongest when environmental contamination is low. The implications of our results for the recording and analysis of disease data and for predicting response to selection are discussed.

  15. Genetic dissection of Flaviviridae host factors through genome-scale CRISPR screens

    PubMed Central

    Marceau, Caleb D.; Puschnik, Andreas S.; Majzoub, Karim; Ooi, Yaw Shin; Brewer, Susan M.; Fuchs, Gabriele; Swaminathan, Kavya; Mata, Miguel A.; Elias, Joshua E.; Sarnow, Peter; Carette, Jan E.

    2016-01-01

    Summary The Flaviviridae are a family of viruses that cause severe human diseases. For example, dengue virus (DENV) is a rapidly emerging pathogen causing an estimated 100 million symptomatic infections annually worldwide1. No approved antivirals are available to date and clinical trials with a tetravalent dengue vaccine showed disappointingly low protection rates2. Also hepatitis C virus (HCV) remains a major medical problem with 160 million chronically infected patients and only expensive treatment on the market3. Despite distinct differences in pathogenesis and mode of transmission, the two viruses share common replication strategies4. A detailed understanding of the host functions that determine viral infection is lacking. Here, we utilized a pooled CRISPR genetic screening strategy5,6 to comprehensively dissect host factors required for these two highly important Flaviviridae members. For DENV, we identified ER-associated multi-protein complexes involved in signal sequence recognition, N-linked glycosylation and ER associated degradation. Dengue virus replication was nearly completely abrogated in cells deficient in the oligosaccharyltransferase (OST) complex. Mechanistic studies pinpointed viral RNA replication and not entry or translation as critical step requiring the OST complex. Moreover, we showed that viral non-structural proteins bind to the OST complex. The identified ER-associated protein complexes were also important for other mosquito-borne flaviviruses including Zika virus, an emerging pathogen causing severe birth defects7. In contrast, the most significant genes identified in the HCV screen were distinct and included viral receptors, RNA binding proteins and enzymes involved in metabolism. We discovered an unexpected link between intracellular FAD levels and HCV replication. This study shows remarkable divergence in host dependency factors between DENV and HCV and illuminates novel host targets for antiviral therapy. PMID:27383987

  16. Chlorella species as hosts for genetic engineering and expression of heterologous proteins: Progress, challenge and perspective.

    PubMed

    Yang, Bo; Liu, Jin; Jiang, Yue; Chen, Feng

    2016-10-01

    The species of Chlorella represent a highly specialized group of green microalgae that can produce high levels of protein. Many Chlorella strains can grow rapidly and achieve high cell density under controlled conditions and are thus considered to be promising protein sources. Many advances in the genetic engineering of Chlorella have occurred in recent years, with significant developments in successful expression of heterologous proteins for various applications. Nevertheless, a lot of obstacles remain to be addressed, and a sophisticated and stable Chlorella expression system has yet to emerge. This review provides a brief summary of current knowledge on Chlorella and an overview of recent progress in the genetic engineering of Chlorella, and highlights the advances in the development of a genetic toolbox of Chlorella for heterologous protein expression. Research directions to further exploit the Chlorella expression system with respect to both challenges and perspectives are also discussed. This paper serves as a comprehensive literature review for the Chlorella community and will provide valuable insights into future exploration of Chlorella as a promising host for heterologous protein expression.

  17. Molecular evolution and population genetics of two Drosophila mettleri cytochrome P450 genes involved in host plant utilization

    PubMed Central

    Bono, Jeremy M.; Matzkin, Luciano M.; Castrezana, Sergio; Markow, Therese A.

    2009-01-01

    Understanding the genetic basis of adaptation is one of the primary goals of evolutionary biology. The evolution of xenobiotic resistance in insects has proven to be an especially suitable arena for studying the genetics of adaptation, and resistant phenotypes are known to result from both coding and regulatory changes. In this study, we examine the evolutionary history and population genetics of two Drosophila mettleri cytochrome P450 genes that are putatively involved in the detoxification of alkaloids present in two of its cactus hosts: saguaro (Carnegiea gigantea) and senita (Lophocereus schottii). Previous studies demonstrated that Cyp28A1 was highly upregulated following exposure to rotting senita tissue while Cyp4D10 was highly upregulated following exposure to rotting saguaro tissue. Here, we show that a subset of sites in Cyp28A1 experienced adaptive evolution specifically in the D. mettleri lineage. Moreover, neutrality tests in several populations were also consistent with a history of selection on Cyp28A1. In contrast, we did not find evidence for positive selection on Cyp4D10, though this certainly does not preclude its involvement in host plant use. A surprising result that emerged from our population genetic analyses was the presence of significant genetic differentiation between flies collected from different host plant species (saguaro and senita) at Organ Pipe National Monument, Arizona, USA. This preliminary evidence suggests that D. mettleri may have evolved into distinctive host races that specialize on different hosts, a possibility that warrants further investigation. PMID:18510584

  18. Parasite-host interaction in malaria: genetic clues and copy number variation

    PubMed Central

    2009-01-01

    In humans, infections contribute highly to mortality and morbidity rates worldwide. Malaria tropica is one of the major infectious diseases globally and is caused by the protozoan parasite Plasmodium falciparum. Plasmodia have accompanied human beings since the emergence of humankind. Due to its pathogenicity, malaria is a powerful selective force on the human genome. Genetic epidemiology approaches such as family and twin studies, candidate gene studies, and disease-association studies have identified a number of genes that mediate relative protection against the severest forms of the disease. New molecular approaches, including genome-wide association studies, have recently been performed to expand our knowledge on the functional effect of human variation in malaria. For the future, a systematic determination of gene-dosage effects and expression profiles of protective genes might unveil the functional impact of structural alterations in these genes on either side of the host-parasite interaction. PMID:19725943

  19. The gut microbiota composition in dichorionic triplet sets suggests a role for host genetic factors.

    PubMed

    Murphy, Kiera; O' Shea, Carol Anne; Ryan, C Anthony; Dempsey, Eugene M; O' Toole, Paul W; Stanton, Catherine; Ross, R Paul

    2015-01-01

    Monozygotic and dizygotic twin studies investigating the relative roles of host genetics and environmental factors in shaping gut microbiota composition have produced conflicting results. In this study, we investigated the gut microbiota composition of a healthy dichorionic triplet set. The dichorionic triplet set contained a pair of monozygotic twins and a fraternal sibling, with similar pre- and post-natal environmental conditions including feeding regime. V4 16S rRNA and rpoB amplicon pyrosequencing was employed to investigate microbiota composition, and the species and strain diversity of the culturable bifidobacterial population was also examined. At month 1, the monozygotic pair shared a similar microbiota distinct to the fraternal sibling. By month 12 however, the profile was more uniform between the three infants. Principal coordinate analysis (PCoA) of the microbiota composition revealed strong clustering of the monozygotic pair at month 1 and a separation of the fraternal infant. At months 2 and 3 the phylogenetic distance between the monozygotic pair and the fraternal sibling has greatly reduced and by month 12 the monozygotic pair no longer clustered separately from the fraternal infant. Pulse field gel electrophoresis (PFGE) analysis of the bifidobacterial population revealed a lack of strain diversity, with identical strains identified in all three infants at month 1 and 12. The microbiota of two antibiotic-treated dichorionic triplet sets was also investigated. Not surprisingly, in both triplet sets early life antibiotic administration appeared to be a major determinant of microbiota composition at month 1, irrespective of zygosity. By month 12, early antibiotic administration appeared to no longer exert such a strong influence on gut microbiota composition. We hypothesize that initially host genetics play a significant role in the composition of an individual's gut microbiota, unless an antibiotic intervention is given, but by month 12 environmental

  20. Population genetic analysis of a parasitic mycovirus to infer the invasion history of its fungal host.

    PubMed

    Schoebel, Corine N; Botella, Leticia; Lygis, Vaidotas; Rigling, Daniel

    2017-02-04

    Hymenoscyphus fraxineus mitovirus 1 (HfMV1) occurs in the fungus Hymenoscyphus fraxineus, an introduced plant pathogen responsible for the devastating ash dieback epidemic in Europe. Here, we explored the prevalence and genetic structure of HfMV1 to elucidate the invasion history of both the virus and the fungal host. A total of 1298 H. fraxineus isolates (181 from Japan and 1117 from Europe) were screened for the presence of this RNA virus and 301 virus-positive isolates subjected to partial sequence analysis of the viral RNA polymerase gene. Our results indicate a high mean prevalence (78.7%) of HfMV1 across European H. fraxineus isolates, which is supported by the observed high transmission rate (average 83.8%) of the mitovirus into sexual spores of its host. In accordance with an expected founder effect in the introduced population in Europe, only 1.1% of the Japanese isolates were tested virus positive. In Europe, HfMV1 shows low nucleotide diversity but a high number of haplotypes, which seem to be subject to strong purifying selection. Phylogenetic and clustering analysis detected two genetically distinct HfMV1 groups, both present throughout Europe. This pattern supports the hypothesis that only two (mitovirus-carrying) H. fraxineus individuals were introduced into Europe as previously suggested from the bi-allelic nature of the fungus. Moreover, our data points to reciprocal mating events between the two introduced individuals, which presumably initiated the ash dieback epidemic in Europe.

  1. Using host-associated genetic markers to investigate sources of fecal contamination in two Vermont streams

    USGS Publications Warehouse

    Medalie, Laura; Matthews, Leslie J.; Stelzer, Erin A.

    2011-01-01

    The use of host-associated Bacteroidales-based 16S ribosomal ribonucleic acid genetic markers was investigated as a tool for providing information to managers on sources of bacterial impairment in Vermont streams. The study was conducted during 2009 in two watersheds on the U.S. Environmental Protection Agency's 303(d) List of Impaired Waters, the Huntington and the Mettawee Rivers. Streamwater samples collected during high-flow and base-flow conditions were analyzed for concentrations of Escherichia coli (E. coli) and Bacteroidales genetic markers (General AllBac, Human qHF183 and BacHum, Ruminant BoBac, and Canid BacCan) to identify humans, ruminants, and canids as likely or unlikely major sources of fecal contamination. Fecal reference samples from each of the potential source groups, as well as from common species of wildlife, were collected during the same season and from the same watersheds as water samples. The results were combined with data from other states to assess marker cross reaction and to relate marker results to E. coli, the regulated water-quality parameter, with a higher degree of statistical significance. Results from samples from the Huntington River collected under different flow conditions on three dates indicated that humans were unlikely to be a major source of fecal contamination, except for a single positive result at one station that indicated the potential for human sources. Ruminants (deer, moose, cow, or sheep) were potential sources of fecal contamination at all six stations on the Huntington River during one high-flow event and at all but two stations during the other high-flow event. Canids were potential sources of fecal contamination at some stations during two high-flow events, with genetic-marker concentrations in samples from two of the six stations showing consistent positive results for canids for both storm dates. A base-flow sample showed no evidence of major fecal contamination in the Huntington River from humans

  2. Host and parasite genetics shape a link between Trypanosoma cruzi infection dynamics and chronic cardiomyopathy.

    PubMed

    Lewis, Michael D; Francisco, Amanda Fortes; Taylor, Martin C; Jayawardhana, Shiromani; Kelly, John M

    2016-10-01

    Host and parasite diversity are suspected to be key factors in Chagas disease pathogenesis. Experimental investigation of underlying mechanisms is hampered by a lack of tools to detect scarce, pleiotropic infection foci. We developed sensitive imaging models to track Trypanosoma cruzi infection dynamics and quantify tissue-specific parasite loads, with minimal sampling bias. We used this technology to investigate cardiomyopathy caused by highly divergent parasite strains in BALB/c, C3H/HeN and C57BL/6 mice. The gastrointestinal tract was unexpectedly found to be the primary site of chronic infection in all models. Immunosuppression induced expansion of parasite loads in the gut and was followed by widespread dissemination. These data indicate that differential immune control of T. cruzi occurs between tissues and shows that the large intestine and stomach provide permissive niches for active infection. The end-point frequency of heart-specific infections ranged from 0% in TcVI-CLBR-infected C57BL/6 to 88% in TcI-JR-infected C3H/HeN mice. Nevertheless, infection led to fibrotic cardiac pathology in all models. Heart disease severity was associated with the model-dependent frequency of dissemination outside the gut and inferred cumulative heart-specific parasite loads. We propose a model of cardiac pathogenesis driven by periodic trafficking of parasites into the heart, occurring at a frequency determined by host and parasite genetics.

  3. Genetic Determinism and Evolutionary Reconstruction of a Host Jump in a Plant Virus.

    PubMed

    Vassilakos, Nikon; Simon, Vincent; Tzima, Aliki; Johansen, Elisabeth; Moury, Benoît

    2016-02-01

    In spite of their widespread occurrence, only few host jumps by plant viruses have been evidenced and the molecular bases of even fewer have been determined. A combination of three independent approaches, 1) experimental evolution followed by reverse genetics analysis, 2) positive selection analysis, and 3) locus-by-locus analysis of molecular variance (AMOVA) allowed reconstructing the Potato virus Y (PVY; genus Potyvirus, family Potyviridae) jump to pepper (Capsicum annuum), probably from other solanaceous plants. Synthetic chimeras between infectious cDNA clones of two PVY isolates with contrasted levels of adaptation to C. annuum showed that the P3 and, to a lower extent, the CI cistron played important roles in infectivity toward C. annuum. The three analytical approaches pinpointed a single nonsynonymous substitution in the P3 and P3N-PIPO cistrons that evolved several times independently and conferred adaptation to C. annuum. In addition to increasing our knowledge of host jumps in plant viruses, this study illustrates also the efficiency of locus-by-locus AMOVA and combined approaches to identify adaptive mutations in the genome of RNA viruses.

  4. Genetic diversity and host range variation of Ralstonia solanacearum strains entering North America.

    PubMed

    Norman, David J; Zapata, Mildred; Gabriel, Dean W; Duan, Y P; Yuen, Jeanne M F; Mangravita-Novo, Arianna; Donahoo, Ryan S

    2009-09-01

    Each year, large volumes of ornamental and food plant propagative stock are imported into the North America; occasionally, Ralstonia solanacearum is found systemically infecting this plant material. In this study, 107 new R. solanacearum strains were collected over a 10-year period from imported propagative stock and compared with 32 previously characterized R. solanacearum strains using repetitive polymerase chain reaction (rep-PCR) element (BOX, ERIC, and REP) primers. Additional strain comparisons were made by sequencing the endoglucanase and the cytochrome b561 genes. Using rep-PCR primers, populations could be distinguished by biovar and, to a limited extent, country of origin and original host. Similarity coefficients among rep-PCR clusters within biovars were relatively low in many cases, indicating that disease outbreaks over time may have been caused by different clonal populations. Similar population differentiations of R. solanacearum were obtained when comparing strain sequences using either the endoglucanase or cytochrome b561 genes. We found that most of the new biovar 1 strains of R. solanacearum entering the United States were genetically distinct from the biovar 1 strains currently found infecting vegetable production. These introduced biovar 1 strains also had a broader host range and could infect not only tomato, tobacco, and potato but also anthurium and pothos and cause symptoms on banana. All introductions into North America of race 3, biovar 2 strains in the last few years have been linked to geranium production and appeared to be clonal.

  5. Genetic evidence confirms polygamous mating system in a crustacean parasite with multiple hosts.

    PubMed

    Jossart, Quentin; Wattier, Rémi A; Kastally, Chedly; Aron, Serge; David, Bruno; De Ridder, Chantal; Rigaud, Thierry

    2014-01-01

    Mating systems are diverse in animals, notably in crustaceans, but can be inferred from a limited set of parameters. Baeza and Thiel (2007) proposed a model predicting mating systems of symbiotic crustaceans with three host characteristics and the risk of predation. These authors proposed five mating systems, ranging from monogamy to polygynandry (where multiple mating occurs for both genders). Using microsatellite loci, we tested the putatively mating system of the ectoparasite crab Dissodactylus primitivus. We determined the mating frequencies of males and females, parentage assignment (COLONY & GERUD software) as well as the contents of female spermathecae. Our results are globally consistent with the model of Baeza and Thiel and showed, together with previous aquarium experiments, that this ectoparasite evolved a polygamous mating system where males and females move between hosts for mate search. Parentage analyses revealed that polyandry is frequent and concerns more than 60% of clutches, with clutches being fertilized by up to 6 different fathers. Polygyny is supported by the detection of eight males having sired two different broods. We also detected a significant paternity skew in 92% of the multipaternal broods. Moreover, this skew is probably higher than the estimation from the brood because additional alleles were detected in most of spermathecae. This high skew could be explained by several factors as sperm competition or cryptic female choice. Our genetic data, combined with previous anatomic analyses, provide consistent arguments to suggest sperm precedence in D. primitivus.

  6. AN ASSESSMENT OF HOST ASSOCIATIONS, GEOGRAPHIC DISTRIBUTIONS, AND GENETIC DIVERSITY OF AVIAN CHEWING LICE (INSECTA: PHTHIRAPTERA) FROM BENIN.

    PubMed

    Takano, Oona M; Mitchell, Preston S; Gustafsson, Daniel R; Adite, Alphonse; Voelker, Gary; Light, Jessica E

    2017-01-07

    Host associations of highly host-specific chewing lice (Insecta: Phthiraptera) across multiple avian species remains fairly undocumented in the West African country of Benin. Two hundred and seventeen bird specimens collected from multiple localities across Benin and housed at the Texas A&M University Biodiversity Research and Teaching Collections were examined for lice. Lice were identified and genetic data (mitochondrial COI and nuclear EF-1α genes) were obtained and phylogenetically analyzed. In total, we found 15 host associations, 7 of which were new to science. Genetically, most lice from Benin were unique and could represent new species. Based on host associations and unique genetic lineages, we estimate we discovered a minimum of 4 and possibly as many as 8 new chewing louse species. Given the lack of current data on chewing louse species distributions in Benin, this study adds to the knowledge of host associations, geographic distribution, and genetic variability of avian chewing louse species in West Africa.

  7. The Genetic Basis of Host Preference and Resting Behavior in the Major African Malaria Vector, Anopheles arabiensis

    PubMed Central

    Main, Bradley J; Lee, Yoosook; Ferguson, Heather M.; Kreppel, Katharina S.; Kihonda, Anicet; Govella, Nicodem J.; Collier, Travis C.; Cornel, Anthony J.; Eskin, Eleazar; Kang, Eun Yong; Nieman, Catelyn C.; Weakley, Allison M.; Lanzaro, Gregory C.

    2016-01-01

    Malaria transmission is dependent on the propensity of Anopheles mosquitoes to bite humans (anthropophily) instead of other dead end hosts. Recent increases in the usage of Long Lasting Insecticide Treated Nets (LLINs) in Africa have been associated with reductions in highly anthropophilic and endophilic vectors such as Anopheles gambiae s.s., leaving species with a broader host range, such as Anopheles arabiensis, as the most prominent remaining source of transmission in many settings. An. arabiensis appears to be more of a generalist in terms of its host choice and resting behavior, which may be due to phenotypic plasticity and/or segregating allelic variation. To investigate the genetic basis of host choice and resting behavior in An. arabiensis we sequenced the genomes of 23 human-fed and 25 cattle-fed mosquitoes collected both in-doors and out-doors in the Kilombero Valley, Tanzania. We identified a total of 4,820,851 SNPs, which were used to conduct the first genome-wide estimates of “SNP heritability” for host choice and resting behavior in this species. A genetic component was detected for host choice (human vs cow fed; permuted P = 0.002), but there was no evidence of a genetic component for resting behavior (indoors versus outside; permuted P = 0.465). A principal component analysis (PCA) segregated individuals based on genomic variation into three groups which were characterized by differences at the 2Rb and/or 3Ra paracentromeric chromosome inversions. There was a non-random distribution of cattle-fed mosquitoes between the PCA clusters, suggesting that alleles linked to the 2Rb and/or 3Ra inversions may influence host choice. Using a novel inversion genotyping assay, we detected a significant enrichment of the standard arrangement (non-inverted) of 3Ra among cattle-fed mosquitoes (N = 129) versus all non-cattle-fed individuals (N = 234; χ2, p = 0.007). Thus, tracking the frequency of the 3Ra in An. arabiensis populations may be of use to infer

  8. Clinical associations of host genetic variations in the genes of cytokines in critically ill patients.

    PubMed

    Belopolskaya, O B; Smelaya, T V; Moroz, V V; Golubev, A M; Salnikova, L E

    2015-06-01

    Host genetic variations may influence a changing profile of biochemical markers and outcome in patients with trauma/injury. The objective of this study was to assess clinical associations of single nucleotide polymorphisms (SNPs) in the genes of cytokines in critically ill patients. A total of 430 patients were genotyped for SNPs in the genes of pro- (IL1B, IL6, IL8) and anti-inflammatory (IL4, IL10, IL13) cytokines. The main end-points were sepsis, mortality and adult respiratory distress syndrome (ARDS). We evaluated the dynamic levels of bilirubin, blood urea nitrogen, creatine kinase, creatinine and lactate dehydrogenase in five points of measurements (between 1 and 14 days after admission) and correlated them with SNPs. High-producing alleles of proinflammatory cytokines protected patients against sepsis (IL1B -511A and IL8 -251A) and mortality (IL1B -511A). High-producing alleles of anti-inflammatory cytokines IL4 -589T and IL13 431A (144Gln) were less frequent in ARDS patients. The carriers of IL6 -174C/C genotypes were prone to the increased levels of biochemical markers and acute kidney and liver insufficiency. Genotype-dependent differences in the levels of biochemical indicators gradually increased to a maximal value on the 14th day after admission. These findings suggest that genetic variability in pro- and anti-inflammatory cytokines may contribute to different clinical phenotypes in patients at high risk of critical illness.

  9. Evidence for genetic diversity of Toxoplasma gondii in selected intermediate hosts in Serbia.

    PubMed

    Marković, Marija; Ivović, Vladimir; Stajner, Tijana; Djokić, Vitomir; Klun, Ivana; Bobić, Branko; Nikolić, Aleksandra; Djurković-Djaković, Olgica

    2014-05-01

    To contribute to the insight into the worldwide population structure of Toxoplasma gondii, we genetically characterized a total of eight strains isolated from intermediate hosts including humans, sheep and pigeons in Serbia. Although parasite DNA was detected in 28.2% (60/213) of the human samples from 162 patients serologically suspected of active toxoplasmosis, as well as in 5/7 seropositive pigeons and in 2/12 seropositive sheep examined, multilocus PCR-RFLP genotyping, using SAG1, 5'SAG2, 3'SAG2, GRA6, 5'GRA7 and 3'GRA7 as markers, was successful in only four human isolates (of which one was isolated from both the bronchoalveolar lavage fluid and blood samples of a single patient), one sheep and three pigeons. Of the eight isolates, five were type II (62.5%), one was type III, one was atypical, and one had a type I allele at GRA6 as the single locus genotyped. Although type II, as elsewhere in Europe, predominated, these results may suggest a higher genetic diversity of T. gondii in Serbia, reflecting local environmental contamination and also the geographical position of the country in South-East Europe.

  10. Global Genetic Differentiation in a Cosmopolitan Pest of Stored Beans: Effects of Geography, Host-Plant Usage and Anthropogenic Factors

    PubMed Central

    Tuda, Midori; Kagoshima, Kumiko; Toquenaga, Yukihiko; Arnqvist, Göran

    2014-01-01

    Genetic differentiation can be promoted allopatrically by geographic isolation of populations due to limited dispersal ability and diversification over time or sympatrically through, for example, host-race formation. In crop pests, the trading of crops across the world can lead to intermixing of genetically distinct pest populations. However, our understanding of the importance of allopatric and sympatric genetic differentiation in the face of anthropogenic genetic intermixing is limited. Here, we examined global sequence variation in two mitochondrial and one nuclear genes in the seed beetle Callosobruchus maculatus that uses different legumes as hosts. We analyzed 180 samples from 42 populations of this stored bean pest from tropical and subtropical continents and archipelagos: Africa, the Middle East, South and Southeast Asia, Oceania and South America. For the mitochondrial genes, there was weak but significant genetic differentiation across continents/archipelagos. Further, we found pronounced differentiation among subregions within continents/archipelagos both globally and within Africa but not within Asia. We suggest that multiple introductions into Asia and subsequent intermixing within Asia have generated this pattern. The isolation by distance hypothesis was supported globally (with or without continents controlled) but not when host species was restricted to cowpeas Vigna unguiculata, the ancestral host of C. maculatus. We also document significant among-host differentiation both globally and within Asia, but not within Africa. We failed to reject a scenario of a constant population size in the recent past combined with selective neutrality for the mitochondrial genes. We conclude that mitochondrial DNA differentiation is primarily due to geographic isolation within Africa and to multiple invasions by different alleles, followed by host shifts, within Asia. The weak inter-continental differentiation is most likely due to frequent inter-continental gene

  11. Global genetic differentiation in a cosmopolitan pest of stored beans: effects of geography, host-plant usage and anthropogenic factors.

    PubMed

    Tuda, Midori; Kagoshima, Kumiko; Toquenaga, Yukihiko; Arnqvist, Göran

    2014-01-01

    Genetic differentiation can be promoted allopatrically by geographic isolation of populations due to limited dispersal ability and diversification over time or sympatrically through, for example, host-race formation. In crop pests, the trading of crops across the world can lead to intermixing of genetically distinct pest populations. However, our understanding of the importance of allopatric and sympatric genetic differentiation in the face of anthropogenic genetic intermixing is limited. Here, we examined global sequence variation in two mitochondrial and one nuclear genes in the seed beetle Callosobruchus maculatus that uses different legumes as hosts. We analyzed 180 samples from 42 populations of this stored bean pest from tropical and subtropical continents and archipelagos: Africa, the Middle East, South and Southeast Asia, Oceania and South America. For the mitochondrial genes, there was weak but significant genetic differentiation across continents/archipelagos. Further, we found pronounced differentiation among subregions within continents/archipelagos both globally and within Africa but not within Asia. We suggest that multiple introductions into Asia and subsequent intermixing within Asia have generated this pattern. The isolation by distance hypothesis was supported globally (with or without continents controlled) but not when host species was restricted to cowpeas Vigna unguiculata, the ancestral host of C. maculatus. We also document significant among-host differentiation both globally and within Asia, but not within Africa. We failed to reject a scenario of a constant population size in the recent past combined with selective neutrality for the mitochondrial genes. We conclude that mitochondrial DNA differentiation is primarily due to geographic isolation within Africa and to multiple invasions by different alleles, followed by host shifts, within Asia. The weak inter-continental differentiation is most likely due to frequent inter-continental gene

  12. Resolving the infection process reveals striking differences in the contribution of environment, genetics and phylogeny to host-parasite interactions

    PubMed Central

    2011-01-01

    Background Infection processes consist of a sequence of steps, each critical for the interaction between host and parasite. Studies of host-parasite interactions rarely take into account the fact that different steps might be influenced by different factors and might, therefore, make different contributions to shaping coevolution. We designed a new method using the Daphnia magna - Pasteuria ramosa system, one of the rare examples where coevolution has been documented, in order to resolve the steps of the infection and analyse the factors that influence each of them. Results Using the transparent Daphnia hosts and fluorescently-labelled spores of the bacterium P. ramosa, we identified a sequence of infection steps: encounter between parasite and host; activation of parasite dormant spores; attachment of spores to the host; and parasite proliferation inside the host. The chances of encounter had been shown to depend on host genotype and environment. We tested the role of genetic and environmental factors in the newly described activation and attachment steps. Hosts of different genotypes, gender and species were all able to activate endospores of all parasite clones tested in different environments; suggesting that the activation cue is phylogenetically conserved. We next established that parasite attachment occurs onto the host oesophagus independently of host species, gender and environmental conditions. In contrast to spore activation, attachment depended strongly on the combination of host and parasite genotypes. Conclusions Our results show that different steps are influenced by different factors. Host-type-independent spore activation suggests that this step can be ruled out as a major factor in Daphnia-Pasteuria coevolution. On the other hand, we show that the attachment step is crucial for the pronounced genetic specificities of this system. We suggest that this one step can explain host population structure and could be a key force behind coevolutionary

  13. Genetic variation and host-parasite specificity of Striga resistance and tolerance in rice: the need for predictive breeding.

    PubMed

    Rodenburg, Jonne; Cissoko, Mamadou; Kayongo, Nicholas; Dieng, Ibnou; Bisikwa, Jenipher; Irakiza, Runyambo; Masoka, Isaac; Midega, Charles A O; Scholes, Julie D

    2017-02-13

    The parasitic weeds Striga asiatica and Striga hermonthica cause devastating yield losses to upland rice in Africa. Little is known about genetic variation in host resistance and tolerance across rice genotypes, in relation to virulence differences across Striga species and ecotypes. Diverse rice genotypes were phenotyped for the above traits in S. asiatica- (Tanzania) and S. hermonthica-infested fields (Kenya and Uganda) and under controlled conditions. New rice genotypes with either ecotype-specific or broad-spectrum resistance were identified. Resistance identified in the field was confirmed under controlled conditions, providing evidence that resistance was largely genetically determined. Striga-resistant genotypes contributed to yield security under Striga-infested conditions, although grain yield was also determined by the genotype-specific yield potential and tolerance. Tolerance, the physiological mechanism mitigating Striga effects on host growth and physiology, was unrelated to resistance, implying that any combination of high, medium or low levels of these traits can be found across rice genotypes. Striga virulence varies across species and ecotypes. The extent of Striga-induced host damage results from the interaction between parasite virulence and genetically determined levels of host-plant resistance and tolerance. These novel findings support the need for predictive breeding strategies based on knowledge of host resistance and parasite virulence.

  14. Limited genetic exchanges between populations of an insect pest living on uncultivated and related cultivated host plants

    PubMed Central

    Vialatte, Aude; Dedryver, Charles-Antoine; Simon, Jean-Christophe; Galman, Marina; Plantegenest, Manuel

    2005-01-01

    Habitats in agroecosystems are ephemeral, and are characterized by frequent disturbances forcing pest species to successively colonize various hosts belonging either to the cultivated or to the uncultivated part of the agricultural landscape. The role of wild habitats as reservoirs or refuges for the aphid Sitobion avenae that colonize cultivated fields was assessed by investigating the genetic structure of populations collected on both cereal crops (wheat, barley and oat) and uncultivated hosts (Yorkshire fog, cocksfoot, bulbous oatgrass and tall oatgrass) in western France. Classical genetic analyses and Bayesian clustering algorithms indicate that genetic differentiation is high between populations collected on uncultivated hosts and on crops, revealing a relatively limited gene flow between the uncultivated margins and the cultivated part of the agroecosystem. A closer genetic relatedness was observed between populations living on plants belonging to the same tribe (Triticeae, Poeae and Aveneae tribes) where aphid genotypes appeared not to be specialized on a single host, but rather using a group of related plant species. Causes of this ecological differentiation and its implications for integrated pest management of S. avenae as cereals pest are discussed. PMID:16024367

  15. A population genetic model of evolution of host-mate attraction and nonhost repulsion in a bark beetle Pityogenes bidentatus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies have shown that the bark beetle Pityogenes bidentatus (Coleoptera, Curculionidae, Scolytinae) avoids volatiles of nonhost trees (Norway spruce, birch, and oak) and healthy host Scotch pine when orienting to aggregation pheromone. A population genetic model of two behavioral genes was hypothe...

  16. Tick-Borne Transmission of Two Genetically Distinct Anaplasma marginale Strains following Superinfection of the Mammalian Reservoir Host

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Strain superinfection affects the dynamics of epidemiological spread of pathogens through a host population. Superinfection has recently been shown to occur for genetically distinct strains of the tick-borne pathogen Anaplasma marginale that encode distinctly different surface protein variants. Supe...

  17. Genetic variability among populations of Fusicladium species from different host trees and geographic locations in the USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peach and almond scab (caused by Fusicladium carpophilum) and pecan scab (caused by F. effusum) cause yield loss, downgrading of fruit, defoliation and subsequent decline of the orchard. To understand the levels of genetic diversity and divergence of the pathogens from different hosts and locations,...

  18. Limited genetic exchanges between populations of an insect pest living on uncultivated and related cultivated host plants.

    PubMed

    Vialatte, Aude; Dedryver, Charles-Antoine; Simon, Jean-Christophe; Galman, Marina; Plantegenest, Manuel

    2005-05-22

    Habitats in agroecosystems are ephemeral, and are characterized by frequent disturbances forcing pest species to successively colonize various hosts belonging either to the cultivated or to the uncultivated part of the agricultural landscape. The role of wild habitats as reservoirs or refuges for the aphid Sitobion avenae that colonize cultivated fields was assessed by investigating the genetic structure of populations collected on both cereal crops (wheat, barley and oat) and uncultivated hosts (Yorkshire fog, cocksfoot, bulbous oatgrass and tall oatgrass) in western France. Classical genetic analyses and Bayesian clustering algorithms indicate that genetic differentiation is high between populations collected on uncultivated hosts and on crops, revealing a relatively limited gene flow between the uncultivated margins and the cultivated part of the agroecosystem. A closer genetic relatedness was observed between populations living on plants belonging to the same tribe (Triticeae, Poeae and Aveneae tribes) where aphid genotypes appeared not to be specialized on a single host, but rather using a group of related plant species. Causes of this ecological differentiation and its implications for integrated pest management of S. avenae as cereals pest are discussed.

  19. Genetic isolation between two sympatric host plant races of the European corn borer, Ostrinia nubilalis Hubner. II: assortative mating and host-plant preferences for oviposition.

    PubMed

    Bethenod, M-T; Thomas, Y; Rousset, F; Frérot, B; Pélozuelo, L; Genestier, G; Bourguet, D

    2005-02-01

    The European corn borer, Ostrinia nubilalis Hubner, colonized maize (Zea mays L.) after its introduction into Europe about 500 years ago and is now considered one of the main pests of this crop. In northern France, two sympatric host races have been described: one feeding on maize and the other on mugwort (Artemisia vulgaris L.) and hop (Humulus lupulus L.). In a previous study, we showed that mating between the two races may be impeded by differences in the timing of moth emergence and in the composition of the sex pheromone produced by the females. In this study, we further investigated the genetic isolation of these two races using strains from the maize (Z strain) and mugwort (E strain) races selected for diagnostic alleles at two allozyme loci. In a cage containing maize and mugwort plants and located in natural conditions, mating between individuals of the same strain occurred more often than mating between males and females of the E and Z strains. In particular, we obtained no evidence for crosses between Z females and E males. We also found that females of the Z strain laid their eggs almost exclusively on maize, whereas females of the E strain laid their eggs preferentially, but not exclusively, on mugwort. These results suggest that the genetic differentiation between the two host races may also be favored by host-plant preference, one of the first steps toward sympatric speciation.

  20. Pervasive effects of a dominant foliar endophytic fungus on host genetic and phenotypic expression in a tropical tree

    PubMed Central

    Mejía, Luis C.; Herre, Edward A.; Sparks, Jed P.; Winter, Klaus; García, Milton N.; Van Bael, Sunshine A.; Stitt, Joseph; Shi, Zi; Zhang, Yufan; Guiltinan, Mark J.; Maximova, Siela N.

    2014-01-01

    It is increasingly recognized that macro-organisms (corals, insects, plants, vertebrates) consist of both host tissues and multiple microbial symbionts that play essential roles in their host's ecological and evolutionary success. Consequently, identifying benefits and costs of symbioses, as well as mechanisms underlying them are research priorities. All plants surveyed under natural conditions harbor foliar endophytic fungi (FEF) in their leaf tissues, often at high densities. Despite producing no visible effects on their hosts, experiments have nonetheless shown that FEF reduce pathogen and herbivore damage. Here, combining results from three genomic, and two physiological experiments, we demonstrate pervasive genetic and phenotypic effects of the apparently asymptomatic endophytes on their hosts. Specifically, inoculation of endophyte-free (E−) Theobroma cacao leaves with Colletotrichum tropicale (E+), the dominant FEF species in healthy T. cacao, induces consistent changes in the expression of hundreds of host genes, including many with known defensive functions. Further, E+ plants exhibited increased lignin and cellulose content, reduced maximum rates of photosynthesis (Amax), and enrichment of nitrogen-15 and carbon-13 isotopes. These phenotypic changes observed in E+ plants correspond to changes in expression of specific functional genes in related pathways. Moreover, a cacao gene (Tc00g04254) highly up-regulated by C. tropicale also confers resistance to pathogen damage in the absence of endophytes or their products in host tissues. Thus, the benefits of increased pathogen resistance in E+ plants are derived in part from up-regulation of intrinsic host defense responses, and appear to be offset by potential costs including reduced photosynthesis, altered host nitrogen metabolism, and endophyte heterotrophy of host tissues. Similar effects are likely in most plant-endophyte interactions, and should be recognized in the design and interpretation of genetic

  1. Genetic polymorphisms in host antiviral genes: associations with humoral and cellular immunity to measles vaccine.

    PubMed

    Haralambieva, Iana H; Ovsyannikova, Inna G; Umlauf, Benjamin J; Vierkant, Robert A; Shane Pankratz, V; Jacobson, Robert M; Poland, Gregory A

    2011-11-08

    Host antiviral genes are important regulators of antiviral immunity and plausible genetic determinants of immune response heterogeneity after vaccination. We genotyped and analyzed 307 common candidate tagSNPs from 12 antiviral genes in a cohort of 745 schoolchildren immunized with two doses of measles-mumps-rubella (MMR) vaccine. Associations between SNPs/haplotypes and measles virus-specific immune outcomes were assessed using linear regression methodologies in Caucasians and African-Americans. Genetic variants within the DDX58/RIG-I gene, including a coding polymorphism (rs3205166/Val800Val), were associated as single-SNPs (p≤0.017; although these SNPs did not remain significant after correction for false discovery rate/FDR) and in haplotype-level analysis, with measles-specific antibody variations in Caucasians (haplotype allele p-value=0.021; haplotype global p-value=0.076). Four DDX58 polymorphisms, in high LD, demonstrated also associations (after correction for FDR) with variations in both measles-specific IFN-γ and IL-2 secretion in Caucasians (p≤0.001, q=0.193). Two intronic OAS1 polymorphisms, including the functional OAS1 SNP rs10774671 (p=0.003), demonstrated evidence of association with a significant allele-dose-related increase in neutralizing antibody levels in African-Americans. Genotype and haplotype-level associations demonstrated the role of ADAR genetic variants, including a non-synonymous SNP (rs2229857/Arg384Lys; p=0.01), in regulating measles virus-specific IFN-γ Elispot responses in Caucasians (haplotype global p-value=0.017). After correction for FDR, 15 single-SNP associations (11 SNPs in Caucasians and 4 SNPs in African-Americans) still remained significant at the q-value<0.20. In conclusion, our findings strongly point to genetic variants/genes, involved in antiviral sensing and antiviral control, as critical determinants, differentially modulating the adaptive immune responses to live attenuated measles vaccine in Caucasians and

  2. Extreme mitochondrial variation in the Atlantic gall crab Opecarcinus hypostegus (Decapoda: Cryptochiridae) reveals adaptive genetic divergence over Agaricia coral hosts

    PubMed Central

    van Tienderen, Kaj M.; van der Meij, Sancia E. T.

    2017-01-01

    The effectiveness of migration in marine species exhibiting a pelagic larval stage is determined by various factors, such as ocean currents, pelagic larval stage duration and active habitat selection. Direct measurement of larval movements is difficult and, consequently, factors determining the gene flow patterns remain poorly understood for many species. Patterns of gene flow play a key role in maintaining genetic homogeneity in a species by dampening the effects of local adaptation. Coral-dwelling gall crabs (Cryptochiridae) are obligate symbionts of stony corals (Scleractinia). Preliminary data showed high genetic diversity on the COI gene for 19 Opecarcinus hypostegus specimens collected off Curaçao. In this study, an additional 176 specimens were sequenced and used to characterize the population structure along the leeward side of Curaçao. Extremely high COI genetic variation was observed, with 146 polymorphic sites and 187 unique haplotypes. To determine the cause of this high genetic diversity, various gene flow scenarios (geographical distance along the coast, genetic partitioning over depth, and genetic differentiation by coral host) were examined. Adaptive genetic divergence across Agariciidae host species is suggested to be the main cause for the observed high intra-specific variance, hypothesised as early signs of speciation in O. hypostegus. PMID:28079106

  3. Effects of parasitic sex-ratio distorters on host genetic structure in the Armadillidium vulgare-Wolbachia association.

    PubMed

    Verne, S; Johnson, M; Bouchon, D; Grandjean, F

    2012-02-01

    In the pill bug Armadillidium vulgare (Crustacea, Oniscidea), Wolbachia facilitates its spread through vertical transmission via the eggs by inducing feminization of genetic males. The spread of feminizing Wolbachia within and across populations is therefore expected to influence mitochondrial DNA (mtDNA) genetic structure by hitchhiking. To test this hypothesis, we analysed nuclear and mtDNA genetic structure, and Wolbachia prevalence in 13 populations of the pill bug host. Wolbachia prevalence (ranging from 0% to 100% of sampled females) was highly variable among populations. All three Wolbachia strains previously observed in A. vulgare were present (wVulC, wVulM and wVulP) with wVulC being the most prevalent (nine of 13 populations). The host showed a genetic structure on five microsatellite loci that is compatible with isolation by distance. The strong genetic structure observed on host mtDNA was correlated with Wolbachia prevalence: three mitotypes were in strong linkage disequilibrium with the three strains of Wolbachia. Neutrality tests showed that the mtDNA polymorphism is not neutral, and we thus suggest that this unusual pattern of mtDNA polymorphism found in A. vulgare was due to Wolbachia.

  4. Host Genetic Factors Associated with Symptomatic Primary HIV Infection and Disease Progression among Argentinean Seroconverters

    PubMed Central

    Coloccini, Romina Soledad; Dilernia, Dario; Ghiglione, Yanina; Turk, Gabriela; Laufer, Natalia; Rubio, Andrea; Socías, María Eugenia; Figueroa, María Inés; Sued, Omar; Cahn, Pedro; Salomón, Horacio; Mangano, Andrea; Pando, María Ángeles

    2014-01-01

    Background Variants in HIV-coreceptor C-C chemokine receptor type 5 (CCR5) and Human leukocyte antigen (HLA) genes are the most important host genetic factors associated with HIV infection and disease progression. Our aim was to analyze the association of these genetic factors in the presence of clinical symptoms during Primary HIV Infection (PHI) and disease progression within the first year. Methods Seventy subjects diagnosed during PHI were studied (55 symptomatic and 15 asymptomatic). Viral load (VL) and CD4 T-cell count were evaluated. HIV progression was defined by presence of B or C events and/or CD4 T-cell counts <350 cell/mm3. CCR5 haplotypes were characterized by polymerase chain reaction and SDM-PCR-RFLP. HLA-I characterization was performed by Sequencing. Results Symptoms during PHI were significantly associated with lower frequency of CCR5-CF1 (1.8% vs. 26.7%, p = 0.006). Rapid progression was significantly associated with higher frequency of CCR5-CF2 (16.7% vs. 0%, p = 0.024) and HLA-A*11 (16.7% vs. 1.2%, p = 0.003) and lower frequency of HLA-C*3 (2.8% vs. 17.5%, p = 0.035). Higher baseline VL was significantly associated with presence of HLA-A*11, HLA-A*24, and absence of HLA-A*31 and HLA-B*57. Higher 6-month VL was significantly associated with presence of CCR5-HHE, HLA-A*24, HLA-B*53, and absence of HLA-A*31 and CCR5-CF1. Lower baseline CD4 T-cell count was significantly associated with presence of HLA-A*24/*33, HLA-B*53, CCR5-CF2 and absence of HLA-A*01/*23 and CCR5-HHA. Lower 6-month CD4 T-cell count was associated with presence of HLA-A*24 and HLA-B*53, and absence of HLA-A*01 and HLA-B*07/*39. Moreover, lower 12-month CD4 T-cell count was significantly associated with presence of HLA-A*33, HLA-B*14, HLA-C*08, CCR5-CF2, and absence of HLA-B*07 and HLA-C*07. Conclusion Several host factors were significantly associated with disease progression in PHI subjects. Most results agree with previous studies performed in other groups

  5. Comprehensive Genetic Analysis of Early Host Body Reactions to the Bioactive and Bio-Inert Porous Scaffolds

    PubMed Central

    Ehashi, Tomo; Takemura, Taro; Hanagata, Nobutaka; Minowa, Takashi; Kobayashi, Hisatoshi; Ishihara, Kazuhiko; Yamaoka, Tetsuji

    2014-01-01

    To design scaffolds for tissue regeneration, details of the host body reaction to the scaffolds must be studied. Host body reactions have been investigated mainly by immunohistological observations for a long time. Despite of recent dramatic development in genetic analysis technologies, genetically comprehensive changes in host body reactions are hardly studied. There is no information about host body reactions that can predict successful tissue regeneration in the future. In the present study, porous polyethylene scaffolds were coated with bioactive collagen or bio-inert poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB) and were implanted subcutaneously and compared the host body reaction to those substrates by normalizing the result using control non-coat polyethylene scaffold. The comprehensive analyses of early host body reactions to the scaffolds were carried out using a DNA microarray assay. Within numerous genes which were expressed differently among these scaffolds, particular genes related to inflammation, wound healing, and angiogenesis were focused upon. Interleukin (IL)-1β and IL-10 are important cytokines in tissue responses to biomaterials because IL-1β promotes both inflammation and wound healing and IL-10 suppresses both of them. IL-1β was up-regulated in the collagen-coated scaffold. Collagen-specifically up-regulated genes contained both M1- and M2-macrophage-related genes. Marked vessel formation in the collagen-coated scaffold was occurred in accordance with the up-regulation of many angiogenesis-inducible factors. The DNA microarray assay provided global information regarding the host body reaction. Interestingly, several up-regulated genes were detected even on the very bio-inert PMB-coated surfaces and those genes include inflammation-suppressive and wound healing-suppressive IL-10, suggesting that not only active tissue response but also the inert response may relates to these genetic regulations. PMID:24454803

  6. Geographical, genetic and functional diversity of antiretroviral host factor TRIMCyp in cynomolgus macaque (Macaca fascicularis)

    PubMed Central

    Saito, Akatsuki; Kono, Ken; Nomaguchi, Masako; Yasutomi, Yasuhiro; Shioda, Tatsuo; Akari, Hirofumi

    2012-01-01

    The antiretroviral factor tripartite motif protein 5 (TRIM5) gene-derived isoform (TRIMCyp) has been found in at least three species of Old World monkey: rhesus (Macaca mulatta), pig-tailed (Macaca nemestrina) and cynomolgus (Macaca fascicularis) macaques. Although the frequency of TRIMCyp has been well studied in rhesus and pig-tailed macaques, the frequency and prevalence of TRIMCyp in cynomolgus macaques remain to be definitively elucidated. Here, the geographical and genetic diversity of TRIM5α/TRIMCyp in cynomolgus macaques was studied in comparison with their anti-lentiviral activity. It was found that the frequency of TRIMCyp in a population in the Philippines was significantly higher than those in Indonesian and Malaysian populations. Major and minor haplotypes of cynomolgus macaque TRIMCyp with single nucleotide polymorphisms in the cyclophilin A domain were also found. The functional significance of the polymorphism in TRIMCyp was examined, and it was demonstrated that the major haplotype of TRIMCyp suppressed human immunodeficiency virus type 1 (HIV-1) but not HIV-2, whilst the minor haplotype of TRIMCyp suppressed HIV-2 but not HIV-1. The major haplotype of TRIMCyp did not restrict a monkey-tropic HIV-1 clone, NL-DT5R, which contains a capsid with the simian immunodeficiency virus-derived loop between α-helices 4 and 5 and the entire vif gene. These results indicate that polymorphisms of TRIMCyp affect its anti-lentiviral activity. Overall, the results of this study will help our understanding of the genetic background of cynomolgus macaque TRIMCyp, as well as the host factors composing species barriers of primate lentiviruses. PMID:22113010

  7. Genetic structure and natural variation associated with host of origin in Penicillium expansum strains causing blue mould.

    PubMed

    Sanzani, S M; Montemurro, C; Di Rienzo, V; Solfrizzo, M; Ippolito, A

    2013-07-15

    Blue mould, caused by Penicillium expansum, is one of the most economically damaging postharvest diseases of pome fruits, although it may affect a wider host range, including sweet cherries and table grapes. Several reports on the role of mycotoxins in plant pathogenesis have been published, but few focussed on the influence of mycotoxins on the variation in host preference amongst producing fungi. In the present study the influence of the host on P. expansum pathogenicity/virulence was investigated, focussing mainly on the relationship with patulin production. Three P. expansum strain groups, originating from apples, sweet cherries, and table grapes (7 strains per host) were grown on their hosts of isolation and on artificial media derived from them. Strains within each P. expansum group proved to be more aggressive and produced more patulin than the other two groups under evaluation when grown on the host from which they originated. Table grape strains were the most aggressive (81% disease incidence) and strongest patulin producers (up to 554μg/g). The difference in aggressiveness amongst strains was appreciable only in the presence of a living host, suggesting that the complex pathogen-host interaction significantly influenced the ability of P. expansum to cause the disease. Incidence/severity of the disease and patulin production proved to be positively correlated, supporting the role of patulin as virulence/pathogenicity factor. The existence of genetic variation amongst isolates was confirmed by the High Resolution Melting method that was set up herein, which permitted discrimination of P. expansum from other species (P. chrysogenum and P. crustosum) and, within the same species, amongst the host of origin. Host effect on toxin production appeared to be exerted at a transcriptional level.

  8. Genetic dissection of host immune response in pneumonia development and progression

    PubMed Central

    Smelaya, Tamara V.; Belopolskaya, Olesya B.; Smirnova, Svetlana V.; Kuzovlev, Artem N.; Moroz, Viktor V.; Golubev, Arkadiy M.; Pabalan, Noel A.; Salnikova, Lyubov E.

    2016-01-01

    The role of host genetic variation in pneumonia development and outcome is poorly understood. We studied common polymorphisms in the genes of proinflammatory cytokines (IL6 rs1800795, IL8 rs4073, IL1B rs16944), anti-inflammatory cytokines (IL10 rs1800896, IL4 rs2243250, IL13 rs20541) and toll-like receptors (TLR2 rs5743708 and rs4696480, TLR4 rs4986791, TLR9 rs352139, rs5743836 and rs187084) in patients with community-acquired pneumonia (CAP) (390 cases, 203 controls) and nosocomial pneumonia (355 cases, 216 controls). Experimental data were included in a series of 11 meta-analyses and eight subset analyses related to pneumonia susceptibility and outcome. TLR2 rs5743708 minor genotype appeared to be associated with CAP/Legionnaires’ disease/pneumococcal disease. In CAP patients, the IL6 rs1800795-C allele was associated with severe sepsis/septic shock/severe systemic inflammatory response, while the IL10 rs1800896-A allele protected against the development of these critical conditions. To contribute to deciphering of the above results, we performed an in silico analysis and a qualitative synthesis of literature data addressing basal and stimulated genotype-specific expression level. This data together with database information on transcription factors’ affinity changes caused by SNPs in putative promoter regions, the results of linkage disequilibrium analysis along with SNPs functional annotations supported assumptions about the complexity underlying the revealed associations. PMID:27725770

  9. Host Genetic Variants and Gene Expression Patterns Associated with Epstein-Barr Virus Copy Number in Lymphoblastoid Cell Lines

    PubMed Central

    Houldcroft, Charlotte J.; Petrova, Velislava; Liu, Jimmy Z.; Frampton, Dan; Anderson, Carl A.; Gall, Astrid; Kellam, Paul

    2014-01-01

    Lymphoblastoid cell lines (LCLs) are commonly used in molecular genetics, supplying DNA for the HapMap and 1000 Genomes Projects, used to test chemotherapeutic agents, and informing the basis of a number of population genetics studies of gene expression. The process of transforming human B cells into LCLs requires the presence of Epstein-Barr virus (EBV), a double-stranded DNA virus which through B-cell immortalisation maintains an episomal virus genome in every cell of an LCL at variable copy numbers. Previous studies have reported that EBV alters host-gene expression and EBV copy number may be under host genetic control. We performed a genome-wide association study of EBV genome copy number in LCLs and found the phenotype to be highly heritable, although no individual SNPs achieved a significant association with EBV copy number. The expression of two host genes (CXCL16 and AGL) was positively correlated and expression of ADARB2 was negatively correlated with EBV copy number in a genotype-independent manner. This study shows an association between EBV copy number and the gene expression profile of LCLs, and suggests that EBV copy number should be considered as a covariate in future studies of host gene expression in LCLs. PMID:25290448

  10. A Comparative Analysis of Genetic Differentiation across Six Shared Willow Host Species in Leaf- and Bud-Galling Sawflies

    PubMed Central

    Leppänen, Sanna A.; Malm, Tobias; Värri, Kaisa; Nyman, Tommi

    2014-01-01

    Genetic divergence and speciation in plant-feeding insects could be driven by contrasting selection pressures imposed by different plant species and taxa. While numerous examples of host-associated differentiation (HAD) have been found, the overall importance of HAD in insect diversification remains unclear, as few studies have investigated its frequency in relation to all speciation events. One promising way to infer the prevalence and repeatability of HAD is to estimate genetic differentiation in multiple insect taxa that use the same set of hosts. To this end, we measured and compared variation in mitochondrial COI and nuclear ITS2 sequences in population samples of leaf-galling Pontania and bud-galling Euura sawflies (Hymenoptera: Tenthredinidae) collected from six Salix species in two replicate locations in northern Fennoscandia. We found evidence of frequent HAD in both species complexes, as individuals from the same willow species tended to cluster together on both mitochondrial and nuclear phylogenetic trees. Although few fixed differences among the putative species were found, hierarchical AMOVAs showed that most of the genetic variation in the samples was explained by host species rather than by sampling location. Nevertheless, the levels of HAD measured across specific pairs of host species were not correlated in the two focal galler groups. Hence, our results support the hypothesis of HAD as a central force in herbivore speciation, but also indicate that evolutionary trajectories are only weakly repeatable even in temporally overlapping radiations of related insect taxa. PMID:25551608

  11. Analysis of Genetic Variation in Brevipalpus yothersi (Acari: Tenuipalpidae) Populations from Four Species of Citrus Host Plants

    PubMed Central

    Salinas-Vargas, Delfina; Santillán-Galicia, Ma. Teresa; Guzmán-Franco, Ariel W.; Hernández-López, Antonio; Ortega-Arenas, Laura D.; Mora-Aguilera, Gustavo

    2016-01-01

    We studied species diversity and genetic variation among populations of Brevipalpus mites from four species of citrus host plants. We sampled mites on orange, lime, grapefruit and mandarin trees from orchards at six localities distributed in the five most important citrus producing states in Mexico. Genetic variation among citrus host plants and localities were assessed by analysis of nucleotide sequence data from fragments of the mitochondrial cytochrome oxidase subunit I (COI). Both Brevipalpus yothersi and B. californicus were found at these sites, and B. yothersi was the most abundant species found on all citrus species and in all localities sampled. B. californicus was found mainly on orange and mandarin and only in two of the states sampled. AMOVA and haplotype network analyses revealed no correlation between B. yothersi genetic population structure and geographical origin or citrus host plant species. Considering that a previous study reported greater genetic diversity in B. yothersi populations from Brazil than we observed in Mexico, we discuss the possibility that the Mexican populations may have originated in the southern region of America. PMID:27736923

  12. Genetic analysis of host-toxin interactions in the wheat-Stagonospora nodorum pathosystem

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stagonospora nodorum, causal agent of Stagonospora nodorum blotch (SNB) in wheat, produces multiple necrosis-inducing host-selective toxins (HSTs) that interact with dominant host sensitivity genes to cause disease. Absence of either the toxin or the dominant host gene precludes recognition and resu...

  13. Genetics of host-pathogen interactions in the wheat-Stagonospora nodorum pathosystem

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stagonospora nodorum causes the disease Stagonospora nodorum blotch (SNB) in wheat. S. nodorum produces numerous host-selective toxins (HSTs), all of which interact with dominant host sensitivity genes to cause disease. These host-toxin interactions are mirror images of classical gene-for-gene inter...

  14. Systems biology and systems genetics - novel innovative approaches to study host-pathogen interactions during influenza infection.

    PubMed

    Kollmus, Heike; Wilk, Esther; Schughart, Klaus

    2014-06-01

    Influenza represents a serious threat to public health with thousands of deaths each year. A deeper understanding of the host-pathogen interactions is urgently needed to evaluate individual and population risks for severe influenza disease and to identify new therapeutic targets. Here, we review recent progress in large scale omics technologies, systems genetics as well as new mathematical and computational developments that are now in place to apply a systems biology approach for a comprehensive description of the multidimensional host response to influenza infection. In addition, we describe how results from experimental animal models can be translated to humans, and we discuss some of the future challenges ahead.

  15. Cell type specificity and host genetic polymorphisms influence antibody-dependent enhancement of dengue virus infection.

    PubMed

    Boonnak, Kobporn; Dambach, Kaitlyn M; Donofrio, Gina C; Tassaneetrithep, Boonrat; Marovich, Mary A

    2011-02-01

    Antibody-dependent enhancement (ADE) is implicated in severe, usually secondary, dengue virus (DV) infections. Preexisting heterotypic antibodies, via their Fc-gamma receptor (FcγR) interactions, may increase disease severity through enhanced target cell infection. Greater numbers of infected target cells may contribute to higher viremia and excess cytokine levels often observed in severe disease. Monocytes, macrophages, and immature and mature dendritic cells (DC) are considered major cellular targets of DV. Apheresis of multiple donors allowed isolation of autologous primary myeloid target cell types for head-to-head comparison of infection rates, viral output, and cytokine production under direct infection (without antibody) or ADE conditions (with antibody). All studied cell types except immature DC supported ADE. All cells undergoing ADE secreted proinflammatory cytokines (interleukin-6 [IL-6] and tumor necrosis factor alpha [TNF-α]) at enhancement titers, but distinct cell-type-specific patterns were observed for other relevant proteins (alpha/beta interferon [IFN-α/β] and IL-10). Macrophages produced type I interferons (IFN-α/β) that were modulated by ADE. Mature DC mainly secreted IFN-β. Interestingly, only monocytes secreted IL-10, and only upon antibody-enhanced infection. While ADE infection rates were remarkably consistent in monocytes (10 to 15%) across donors, IL-10 protein levels varied according to previously described regulatory single nucleotide polymorphisms (SNPs) in the IL-10 promoter region. The homozygous GCC haplotype was associated with high-level IL-10 secretion, while the ACC and ATA haplotypes produced intermediate and low levels of IL-10, respectively. Our data suggest that ADE effects are cell type specific, are influenced by host genetics, and, depending on relative infection rates, may further contribute to the complexity of DV pathogenesis.

  16. Effect of host genetics on incidence of HIV neuroretinal disorder in patients with AIDS

    PubMed Central

    Sezgin, Efe; Hendrickson, Sher L.; Jabs, Douglas A.; Van Natta, Mark L.; Lewis, Richard A.; Troyer, Jennifer L.; O’Brien, Stephen J.

    2010-01-01

    Approximately 10 to 15% of patients with AIDS but without ocular opportunistic infections will have a presumed neuroretinal disorder (HIV-NRD), manifested by reduced contrast sensitivity and abnormal visual fields. The loss of contrast sensitivity often is sufficient to impair reading speed. To evaluate the effect of host genetics on HIV-NRD, we explored validated AIDS restriction gene variants CCR5Δ32, CCR2-64I, CCR5 P1, SDF-3`A, IL-10-5`A, RANTES -403A, RANTES -28G, RANTES-In1.1C, CX3CR1-249I, CX3CR1-280M, IFNG-179T, MDR1-3435T, and MCP-1364G, each of which has been implicated previously to influence HIV-1 infection, AIDS progression, therapy response, and antiviral drug metabolism, and an IL-10 receptor gene, IL-10R1, in the Longitudinal Study of the Ocular Complications of AIDS (LSOCA) cohort. In European Americans (cases=55, controls=290), IL-10-5`A variant and its promoter haplotype (HR=2.09, CI: 1.19–3.67, P = 0.01); in African Americans (cases=54, controls=180) RANTES-In1.1C and the associated haplotype (HR=2.72, CI: 1.48–5.00, P = 0.001), showed increased HIV-NRD susceptibility. While sample sizes are small and P values do not pass a strict Bonferroni correction, our results suggest that, in European Americans, an IL-10-related pathway, and, in African Americans, chemokine receptor ligand polymorphisms in RANTES are risk factors for HIV- NRD development. Clearly, further studies are warrented. PMID:20531015

  17. Dietary input of microbes and host genetic variation shape among-population differences in stickleback gut microbiota

    PubMed Central

    Smith, Chris CR; Snowberg, Lisa K; Gregory Caporaso, J; Knight, Rob; Bolnick, Daniel I

    2015-01-01

    To explain differences in gut microbial communities we must determine how processes regulating microbial community assembly (colonization, persistence) differ among hosts and affect microbiota composition. We surveyed the gut microbiota of threespine stickleback (Gasterosteus aculeatus) from 10 geographically clustered populations and sequenced environmental samples to track potential colonizing microbes and quantify the effects of host environment and genotype. Gut microbiota composition and diversity varied among populations. These among-population differences were associated with multiple covarying ecological variables: habitat type (lake, stream, estuary), lake geomorphology and food- (but not water-) associated microbiota. Fish genotype also covaried with gut microbiota composition; more genetically divergent populations exhibited more divergent gut microbiota. Our results suggest that population level differences in stickleback gut microbiota may depend more on internal sorting processes (host genotype) than on colonization processes (transient environmental effects). PMID:25909977

  18. Low genetic diversity in a snail intermediate host (Biomphalaria pfeifferi Krass, 1848) and schistosomiasis transmission in the Senegal River Basin.

    PubMed

    Campbell, G; Noble, L R; Rollinson, D; Southgate, V R; Webster, J P; Jones, C S

    2010-01-01

    Population genetic perturbations of intermediate hosts, often a consequence of human pressure on environmental resources, can precipitate unexpectedly severe disease outbreaks. Such disturbances are set to become increasingly common following range changes concomitant with climate shifts, dwindling natural resources and major infrastructure changes such as hydroprojects. Construction of the Diama dam in the Senegal River Basin (SRB) reduced river salinity, enabling the freshwater snail intermediate host Biomphalaria pfeifferi to rapidly expand its distribution. A serious public health problem ensued, with an epidemic of intestinal schistosomiasis occurring in the previously schistosome-free Richard-Toll region within 2 years. The current study aimed to assess the population variability of B. pfeifferi in the SRB, and speculate upon its subsequent impact on host-parasite interactions following such engineered ecological change. Genetic variation at nine polymorphic microsatellite loci revealed little population differentiation in SRB snails compared with those from natural habitats in Zimbabwe, where Schistosoma mansoni transmission is much lower. 'Open' SRB habitats are associated with greater water contact, smaller population sizes and less genetic diversity, with sites downstream of Richard-Toll showing greater inter- and intrapopulation variation, concomitant with less frequent human contact. These observations may be explained by rapid expansion into pristine habitat selecting for high fecundity genotypes at the expense of schistosome resistance, presenting S. mansoni with genetically homogenous highly fecund susceptible populations around the focal point, promoting development of a highly compatible host-parasite relationship. Longitudinal study of such systems may prove important in predicting public health risks engendered by future environmental engineering projects.

  19. Genomic Evidence for the Evolution of Streptococcus equi: Host Restriction, Increased Virulence, and Genetic Exchange with Human Pathogens

    PubMed Central

    Paillot, Romain; Steward, Karen F.; Webb, Katy; Ainslie, Fern; Jourdan, Thibaud; Bason, Nathalie C.; Holroyd, Nancy E.; Mungall, Karen; Quail, Michael A.; Sanders, Mandy; Simmonds, Mark; Willey, David; Brooks, Karen; Aanensen, David M.; Spratt, Brian G.; Jolley, Keith A.; Maiden, Martin C. J.; Kehoe, Michael; Chanter, Neil; Bentley, Stephen D.; Robinson, Carl; Maskell, Duncan J.; Parkhill, Julian; Waller, Andrew S.

    2009-01-01

    The continued evolution of bacterial pathogens has major implications for both human and animal disease, but the exchange of genetic material between host-restricted pathogens is rarely considered. Streptococcus equi subspecies equi (S. equi) is a host-restricted pathogen of horses that has evolved from the zoonotic pathogen Streptococcus equi subspecies zooepidemicus (S. zooepidemicus). These pathogens share approximately 80% genome sequence identity with the important human pathogen Streptococcus pyogenes. We sequenced and compared the genomes of S. equi 4047 and S. zooepidemicus H70 and screened S. equi and S. zooepidemicus strains from around the world to uncover evidence of the genetic events that have shaped the evolution of the S. equi genome and led to its emergence as a host-restricted pathogen. Our analysis provides evidence of functional loss due to mutation and deletion, coupled with pathogenic specialization through the acquisition of bacteriophage encoding a phospholipase A2 toxin, and four superantigens, and an integrative conjugative element carrying a novel iron acquisition system with similarity to the high pathogenicity island of Yersinia pestis. We also highlight that S. equi, S. zooepidemicus, and S. pyogenes share a common phage pool that enhances cross-species pathogen evolution. We conclude that the complex interplay of functional loss, pathogenic specialization, and genetic exchange between S. equi, S. zooepidemicus, and S. pyogenes continues to influence the evolution of these important streptococci. PMID:19325880

  20. Genetic architecture of gene expression underlying variation in host response to porcine reproductive and respiratory syndrome virus infection

    PubMed Central

    Kommadath, Arun; Bao, Hua; Choi, Igseo; Reecy, James M.; Koltes, James E.; Fritz-Waters, Elyn; Eisley, Chris J.; Grant, Jason R.; Rowland, Robert R. R.; Tuggle, Christopher K.; Dekkers, Jack C. M.; Lunney, Joan K.; Guan, Le Luo; Stothard, Paul; Plastow, Graham S.

    2017-01-01

    It has been shown that inter-individual variation in host response to porcine reproductive and respiratory syndrome (PRRS) has a heritable component, yet little is known about the underlying genetic architecture of gene expression in response to PRRS virus (PRRSV) infection. Here, we integrated genome-wide genotype, gene expression, viremia level, and weight gain data to identify genetic polymorphisms that are associated with variation in inter-individual gene expression and response to PRRSV infection in pigs. RNA-seq analysis of peripheral blood samples collected just prior to experimental challenge (day 0) and at 4, 7, 11 and 14 days post infection from 44 pigs revealed 6,430 differentially expressed genes at one or more time points post infection compared to the day 0 baseline. We mapped genetic polymorphisms that were associated with inter-individual differences in expression at each day and found evidence of cis-acting expression quantitative trait loci (cis-eQTL) for 869 expressed genes (qval < 0.05). Associations between cis-eQTL markers and host response phenotypes using 383 pigs suggest that host genotype-dependent differences in expression of GBP5, GBP6, CCHCR1 and CMPK2 affect viremia levels or weight gain in response to PRRSV infection. PMID:28393889

  1. Skin-scale genetic structure of Sarcoptes scabiei populations from individual hosts: empirical evidence from Iberian ibex-derived mites.

    PubMed

    Alasaad, S; Soglia, D; Sarasa, M; Soriguer, R C; Pérez, J M; Granados, J E; Rasero, R; Zhu, X Q; Rossi, L

    2008-12-01

    The objective of the present study was to examine the extent of genetic diversity among Sarcoptes scabiei individuals belonging to different skin subunits of the body from individual mangy hosts. Ten microsatellite primers were applied on 44 individual S. scabiei mites from three mangy Iberian ibexes from Sierra Nevada Mountain in Spain. Dendrograms of the mites from the individual Iberian ibexes, showing the proportion of shared alleles between pairs of individual mites representing three skin subpopulations (head, back, and abdomen subunits), allowed the clustering of some mite samples up to their skin subunits. This genetic diversity of S. scabiei at skin-scale did not have the same pattern in all considered hosts: for the first Iberian ibex (Cp1), only mites from the head subunit were grouped together; in the second individual (Cp2), the clustering was detected only for mites from the abdomen subunit; and for the third one (Cp3), only mites from the back subunit were clustered together. Our results suggest that the local colonization dynamics of S. scabiei would have influenced the nonrandom distribution of this ectoparasite, after a single infestation. Another presumable explanation to this skin-scale genetic structure could be the repeated infestations. To our knowledge, this is the first documentation of genetic structuring among S. scabiei at individual host skin-scale. Further studies are warranted to highlight determining factors of such trend, but the pattern underlined in the present study should be taken into account in diagnosis and monitoring protocols for studying the population genetic structure and life cycle of this neglected but important ectoparasite.

  2. Interactions of HIV and drugs of abuse: the importance of glia, neural progenitors, and host genetic factors.

    PubMed

    Hauser, Kurt F; Knapp, Pamela E

    2014-01-01

    Considerable insight has been gained into the comorbid, interactive effects of HIV and drug abuse in the brain using experimental models. This review, which considers opiates, methamphetamine, and cocaine, emphasizes the importance of host genetics and glial plasticity in driving the pathogenic neuron remodeling underlying neuro-acquired immunodeficiency syndrome and drug abuse comorbidity. Clinical findings are less concordant than experimental work, and the response of individuals to HIV and to drug abuse can vary tremendously. Host-genetic variability is important in determining viral tropism, neuropathogenesis, drug responses, and addictive behavior. However, genetic differences alone cannot account for individual variability in the brain "connectome." Environment and experience are critical determinants in the evolution of synaptic circuitry throughout life. Neurons and glia both exercise control over determinants of synaptic plasticity that are disrupted by HIV and drug abuse. Perivascular macrophages, microglia, and to a lesser extent astroglia can harbor the infection. Uninfected bystanders, especially astroglia, propagate and amplify inflammatory signals. Drug abuse by itself derails neuronal and glial function, and the outcome of chronic exposure is maladaptive plasticity. The negative consequences of coexposure to HIV and drug abuse are determined by numerous factors including genetics, sex, age, and multidrug exposure. Glia and some neurons are generated throughout life, and their progenitors appear to be targets of HIV and opiates/psychostimulants. The chronic nature of HIV and drug abuse appears to result in sustained alterations in the maturation and fate of neural progenitors, which may affect the balance of glial populations within multiple brain regions.

  3. Tests for the existence of genetic determination or conditioning in host selection by Anopheles albimanus (Diptera: Culicidae).

    PubMed

    Arredondo-Jimenez, J I; Bown, D N; Rodriguez, M H; Villarreal, C; Loyola, E G; Frederickson, C E

    1992-09-01

    The existence of sympatric populations within Anopheles albimanus Wiedemann with specific host preferences and the question of whether host selection has a genetic basis or is a learned characteristic were investigated. Progeny of wild females collected from corrals or human bait were reared in an insectary. F1 females were fed on a cow or on a human host, allowed to oviposit, and then were released in an experimental hut divided into three compartments. The side rooms occupied by two human or one calf baits were connected by a "funnel-like" cone with the central room in which mosquitoes were released. Females were released at 2000 hours and recaptured the next morning at 0600 hours. A fixed proportion of mosquitoes selected either host (approximately 65% cow and 35% human), irrespective of their parental origin or source of the first blood meal. The data indicate that the existence of cryptic populations with anthropophilic habits is unlikely and that a "learned" host selection also may be ruled out.

  4. Symbiodinium biogeography tracks environmental patterns rather than host genetics in a key Caribbean reef-builder, Orbicella annularis

    PubMed Central

    Tonk, Linda; Chollett, Iliana; Ortiz, Juan-Carlos; Dove, Sophie; Hoegh-Guldberg, Ove; Mumby, Peter J.

    2016-01-01

    The physiological performance of a reef-building coral is a combined outcome of both the coral host and its algal endosymbionts, Symbiodinium. While Orbicella annularis—a dominant reef-building coral in the Wider Caribbean—is known to be a flexible host in terms of the diversity of Symbiodinium types it can associate with, it is uncertain how this diversity varies across the Caribbean, and whether spatial variability in the symbiont community is related to either O. annularis genotype or environment. Here, we target the Symbiodinium-ITS2 gene to characterize and map dominant Symbiodinium hosted by O. annularis at an unprecedented spatial scale. We reveal northwest–southeast partitioning across the Caribbean, both in terms of the dominant symbiont taxa hosted and in assemblage diversity. Multivariate regression analyses incorporating a suite of environmental and genetic factors reveal that observed spatial patterns are predominantly explained by chronic thermal stress (summer temperatures) and are unrelated to host genotype. Furthermore, we were able to associate the presence of specific Symbiodinium types with local environmental drivers (for example, Symbiodinium C7 with areas experiencing cooler summers, B1j with nutrient loading and B17 with turbidity), associations that have not previously been described. PMID:27807263

  5. Host Genetic Factors Affect Susceptibility to Norovirus Infections in Burkina Faso

    PubMed Central

    Nordgren, Johan; Nitiema, Léon W.; Ouermi, Djeneba; Simpore, Jacques; Svensson, Lennart

    2013-01-01

    Norovirus (NoV) constitutes the second most common viral pathogen causing pediatric diarrhea after rotavirus. In Africa, diarrhea is a major health problem in children, and yet few studies have been performed regarding NoV. The association of histo-blood group antigens (HBGA) and susceptibility to NoV infection is well established in Caucasian populations with non-secretors being resistant to many common NoV strains. No study regarding HBGA and NoV susceptibility has yet been performed in Africa. We collected 309 stool and 208 saliva samples from diarrheal children in Ouagadougou, Burkina Faso; May 2009 to March 2010. NoV was detected using real-time PCR, and genotyped by sequencing. Saliva samples were ABO, Lewis and secretor phenotyped using in house ELISA assays. NoV was detected in 12% (n = 37) of the samples. The genotype diversity was unusually large; overall the 37 positive samples belonged to 14 genotypes. Only children <2 years of age were NoV positive and the GII.4 NoVs were more frequent in the late dry season (Jan-May). NoV infections were observed less in children with the secretor-negative phenotype or blood group A (OR 0.18; p = 0.012 and OR 0.31; p = 0.054; respectively), with two non-secretors infected with genotypes GII.7 and GII.4 respectively. Lewis-negative (Lea−b−) children, representing 32% of the study population, were susceptible to GII, but were not infected with any NoV GI. GII.4 strains preferentially infected children with blood group B whereas secretor-positive children with blood group O were infected with the largest variety of genotypes. This is the first study identifying host genetic factors associated with susceptibility to NoV in an African population, and suggests that while the non-secretor phenotype provides protection; the Lewis b antigen is not necessary for GII infection. PMID:23894502

  6. Does a facultative precocious life cycle predispose the marine trematode Proctoeces cf. lintoni to inbreeding and genetic differentiation among host species?

    PubMed

    Valdivia, I M; Criscione, C D; Cárdenas, L; Durán, C P; Oliva, M E

    2014-03-01

    Intraspecific variability in parasite life cycle complexity (number of hosts and species of hosts in the life cycle) may have an impact how parasite genetic variation is partitioned among individual parasites, host individuals or host species within a given area. Among digenean trematodes, a three-host life cycle is common. However, a few species are precocious and may reach sexual maturity in what is typically regarded as the second intermediate host. The objective of this study was to determine whether a precocious life cycle predisposes digeneans to possible inbreeding or genetic subdivision among host species. As a study system, we used the digenean Proctoeces cf. lintoni whose metacercariae precociously mature (facultative) without a cyst wall in the gonads of multiple sympatric species of keyhole limpets (Fissurella spp.), typically regarded as the second intermediate hosts. Genotyped parasites were collected from four species of limpets and the clingfish Sicyases sanguineus, the third and final host where sexual maturity occurs. We found very high microsatellite diversity, Hardy-Weinberg equilibrium over all genotyped individuals, and little to no genetic structuring among parasites collected from the different host species. The fact that metacercariae do not encyst in the keyhole limpets, coupled with the high mixing potential of an aquatic environment, likely promote panmixia in local populations of P. cf. lintoni.

  7. Genetic characterization of flea-derived Bartonella species from native animals in Australia suggests host-parasite co-evolution.

    PubMed

    Kaewmongkol, Gunn; Kaewmongkol, Sarawan; McInnes, Linda M; Burmej, Halina; Bennett, Mark D; Adams, Peter J; Ryan, Una; Irwin, Peter J; Fenwick, Stanley G

    2011-12-01

    Fleas are important arthropod vectors for a variety of diseases in veterinary and human medicine, and bacteria belonging to the genus Bartonella are among the organisms most commonly transmitted by these ectoparasites. Recently, a number of novel Bartonella species and novel species candidates have been reported in marsupial fleas in Australia. In the present study the genetic diversity of marsupial fleas was investigated; 10 species of fleas were collected from seven different marsupial and placental mammal hosts in Western Australia including woylies (Bettongia penicillata), western barred bandicoots (Perameles bougainville), mardos (Antechinus flavipes), bush rats (Rattus fuscipes), red foxes (Vulpes vulpes), feral cats (Felis catus) and rabbits (Oryctolagus cuniculus). PCR and sequence analysis of the cytochrome oxidase subunit I (COI) and the 18S rRNA genes from these fleas was performed. Concatenated phylogenetic analysis of the COI and 18S rRNA genes revealed a close genetic relationship between marsupial fleas, with Pygiopsylla hilli from woylies, Pygiopsylla tunneyi from western barred bandicoots and Acanthopsylla jordani from mardos, forming a separate cluster from fleas collected from the placental mammals in the same geographical area. The clustering of Bartonella species with their marsupial flea hosts suggests co-evolution of marsupial hosts, marsupial fleas and Bartonella species in Australia.

  8. Do pathogens reduce genetic diversity of their hosts? Variable effects of sylvatic plague in black-tailed prairie dogs.

    PubMed

    Sackett, Loren C; Collinge, Sharon K; Martin, Andrew P

    2013-05-01

    Introduced diseases can cause dramatic declines in-and even the loss of-natural populations. Extirpations may be followed by low recolonization rates, leading to inbreeding and a loss of genetic variation, with consequences on population viability. Conversely, extirpations may create vacant habitat patches that individuals from multiple source populations can colonize, potentially leading to an influx of variation. We tested these alternative hypotheses by sampling 15 colonies in a prairie dog metapopulation during 7 years that encompassed an outbreak of sylvatic plague, providing the opportunity to monitor genetic diversity before, during and after the outbreak. Analysis of nine microsatellite loci revealed that within the metapopulation, there was no change in diversity. However, within extirpated colonies, patterns varied: In half of the colonies, allelic richness after recovery was less than the preplague conditions, and in the other half, richness was greater than the preplague conditions. Finally, analysis of variation within individuals revealed that prairie dogs present in recolonized colonies had higher heterozygosity than those present before plague. We confirmed plague survivorship in six founders; these individuals had significantly higher heterozygosity than expected by chance. Collectively, our results suggest that high immigration rates can maintain genetic variation at a regional scale despite simultaneous extirpations in spatially proximate populations. Thus, virulent diseases may increase genetic diversity of host populations by creating vacant habitats that allow an influx of genetic diversity. Furthermore, even highly virulent diseases may not eliminate individuals randomly; rather, they may selectively remove the most inbred individuals.

  9. First detection of Sarcoptes scabiei from domesticated pig (Sus scrofa) and genetic characterization of S. scabiei from pet, farm and wild hosts in Israel.

    PubMed

    Erster, Oran; Roth, Asael; Pozzi, Paolo S; Bouznach, Arieli; Shkap, Varda

    2015-08-01

    In this report we describe for the first time the detection of Sarcoptes scabiei type suis mites on domestic pigs in Israel and examine its genetic variation compared with S. sabiei from other hosts. Microscopic examination of skin samples from S. scabiei-infested pigs (Sus scrofa domesticus) revealed all developmental stages of S. scabiei. To detect genetic differences between S. scabiei from different hosts, samples obtained from pig, rabbits (Orictolagus cuniculus), fox (Vulpes vulpes), jackal (Canis aureus) and hedgehog (Erinaceus concolor) were compared with GenBank-annotated sequences of three genetic markers. Segments from the following genes were examined: cytochrome C oxidase subunit 1 (COX1), glutathione-S-transferase 1 (GST1), and voltage-sensitive sodium channel (VSSC). COX1 analysis did not show correlation between host preference and genetic identity. However, GST1 and VSSC had a higher percentage of identical sites within S. scabiei type suis sequences, compared with samples from other hosts. Taking into account the limited numbers of GST1 and VSSC sequences available for comparison, this high similarity between sequences of geographically-distant, but host-related populations, may suggest that different host preference is at least partially correlated with genetic differences. This finding may help in future studies of the factors that drive host preferences in this parasite.

  10. Understanding phyolgenetic relationships among species in the Nosema/Vairimorpha clade: what does genetic similarity say about host switching in the microsporidia?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microsporidian species with high genetic identity based on rDNA phylogenies have been isolated from different insect species and even higher level host taxa across the globe. Complicating the picture, for genera such as the lepidopteran Nosema and Vairimorpha, isolates from different hosts may be mo...

  11. Influence of NleH effector expression, host genetics, and inflammation on Citrobacter rodentium colonization of mice.

    PubMed

    Feuerbacher, Leigh Ann; Hardwidge, Philip R

    2014-05-01

    The Escherichia coli NleH1 and NleH2 virulence proteins differentially regulate host transcription of innate immunity genes. The mouse pathogen Citrobacter rodentium encodes one NleH protein, which functions equivalently to E. coli NleH1. We examined the impact of host genetics and intestinal inflammation on the contribution of NleH to C. rodentium colonization of mice differing in LPS responsiveness. NleH expression was detrimental to C. rodentium in C57BL/10ScNJ mice, which do not mount LPS-induced inflammatory responses. This phenotype was reversed if inflammation was induced by chemical means. C. rodentium that expressed both E. coli NleH1 and NleH2 was hypervirulent in C3H/HeJ mice.

  12. Genetic Assignment Methods for Gaining Insight into the Management of Infectious Disease by Understanding Pathogen, Vector, and Host Movement

    PubMed Central

    Remais, Justin V.; Xiao, Ning; Akullian, Adam; Qiu, Dongchuan; Blair, David

    2011-01-01

    For many pathogens with environmental stages, or those carried by vectors or intermediate hosts, disease transmission is strongly influenced by pathogen, host, and vector movements across complex landscapes, and thus quantitative measures of movement rate and direction can reveal new opportunities for disease management and intervention. Genetic assignment methods are a set of powerful statistical approaches useful for establishing population membership of individuals. Recent theoretical improvements allow these techniques to be used to cost-effectively estimate the magnitude and direction of key movements in infectious disease systems, revealing important ecological and environmental features that facilitate or limit transmission. Here, we review the theory, statistical framework, and molecular markers that underlie assignment methods, and we critically examine recent applications of assignment tests in infectious disease epidemiology. Research directions that capitalize on use of the techniques are discussed, focusing on key parameters needing study for improved understanding of patterns of disease. PMID:21552326

  13. Genetic background of host-pathogen interaction between Cucumis sativus L. and Pseudomonas syringae pv. lachrymans.

    PubMed

    Olczak-Woltman, H; Schollenberger, M; Niemirowicz-Szczytt, K

    2009-01-01

    The interplay of plant resistance mechanisms and bacterial pathogenicity is very complex. This applies also to the interaction that takes place between the pathogen Pseudomonas syringae pv. lachrymans (Smith et Bryan) and the cucumber (Cucumis sativus L.) as its host plant. Research on P. syringae pv. lachrymans has led to the discovery of specific factors produced during pathogenesis, i.e. toxins or enzymes. Similarly, studies on cucumber have identified the specific types of plant resistance expressed, namely Systemic Acquired Resistance (SAR) or Induced Systemic Resistance (ISR). This paper presents a summary of the current state of knowledge about this particular host-pathogen interaction, with reference to general information about interactions of P. syringae pathovars with host plants.

  14. Response of a gall wasp community to genetic variation in the host plant Quercus crispula: a test using half-sib families

    NASA Astrophysics Data System (ADS)

    Ito, Masato; Ozaki, Kenichi

    2005-02-01

    The structure of a herbivore community may change consistently along the genetic cline of a host plant, change at particular points along the cline, or respond independently of the cline. To reveal such relationships between a gall wasp community and genetic variation in the host plant Quercus crispula, we examined patterns in the species richness and abundance of gall wasps along a genetic cline of the host plant, using 12 half-sib families from six different regions. The genetic relationships among the half-sib families of Q. crispula were quantified on the basis of leaf morphology, which represented a morphological cline from leaves typical of Q. crispula to leaves resembling another oak species, Q. dentata. The morphological cline could be regarded as a genetic cline caused by a history of hybridization with Q. dentata. The mean numbers of gall types varied among the half-sib families, but did not show a consistent increase or decrease along the genetic cline. This pattern could be explained by the fact that responses to host plant variation differed among the gall wasp species. The half-sib families were classified into three groups based on an ordination analysis of the species composition of the gall wasp community that to some extent also reflected the genetic cline of Q. crispula. This suggests that the species composition of gall wasps changed intermittently along the genetic cline, rather than gradually and consistently along the cline.

  15. Interactions of HIV and drugs of abuse: the importance of glia, neural progenitors, and host genetic factors

    PubMed Central

    Hauser, Kurt F.; Knapp, Pamela E.

    2015-01-01

    Considerable insight has been gained into the comorbid, interactive effects of HIV and drug abuse in the brain using experimental models. This review, which considers opiates, methamphetamine, and cocaine, emphasizes the importance of host genetics and glial plasticity in driving the pathogenic neuron remodeling underlying neuro-acquired immunodeficiency syndrome (neuroAIDS) and drug abuse comorbidity. Clinical findings are less concordant than experimental work, and the response of individuals to HIV and to drug abuse can vary tremendously. Host-genetic variability is important in determining viral tropism, neuropathogenesis, drug responses, and addictive behavior. However, genetic differences alone cannot account for individual variability in the brain “connectome”. Environment and experience are critical determinants in the evolution of synaptic circuitry throughout life. Neurons and glia both exercise control over determinants of synaptic plasticity that are disrupted by HIV and drug abuse. Perivascular macrophages, microglia, and to a lesser extent astroglia can harbor the infection. Uninfected bystanders, especially astroglia, propagate and amplify inflammatory signals. Drug abuse by itself derails neuronal and glial function, and the outcome of chronic exposure is maladaptive plasticity. The negative consequences of coexposure to HIV and drug abuse are determined by numerous factors including genetics, sex, age, and multidrug exposure. Glia and some neurons are generated throughout life and their progenitors appear to be targets of HIV and opiates/psychostimulants. The chronic nature of HIV and drug abuse appears to result in sustained alterations in the maturation and fate of neural progenitors, which may affect the balance of glial populations within multiple brain regions. PMID:25175867

  16. Genetic analysis of Phytophthora nicotianae populations from different hosts using microsatellite markers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two hundred thirty-one isolates of P. nicotianae representing 14 populations from different host genera, including agricultural crops (Citrus, Nicotiana, and Lycopersicon), potted ornamental species in nurseries (Lavandula, Convolvulus, Myrtus, Correa and Ruta) and other plant genera of lesser econo...

  17. Host plant associated genetic divergence of two Diatraea spp. (Lepidoptera: Crambidae) stemborers on novel crop plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diatraea lineolata and Diatraea saccharalis (Lepidoptera: Crambidae) are moths with stemboring larvae that feed and develop on economically important grasses. This study investigated whether these moths have diverged from a native host plant, corn, onto introduced crop plants including sorghum, suga...

  18. COMPETITIVE METAGENOMIC DNA HYBRIDIZATION IDENTIFIES HOST-SPECIFIC MICROBIAL GENETIC MARKERS IN COW FECAL SAMPLES

    EPA Science Inventory

    Several PCR methods have recently been developed to identify fecal contamination in surface waters. In all cases, researchers have relied on one gene or one microorganism for selection of host specific markers. Here, we describe the application of a genome fragment enrichment met...

  19. COMPETITIVE METAGENOMIC DNA HYBRIDIZATION IDENTIFIES HOST-SPECIFIC GENETIC MARKERS IN CATTLE FECAL SAMPLES - ABSTRACT

    EPA Science Inventory

    Several PCR methods have recently been developed to identify fecal contamination in surface waters. In all cases, researchers have relied on one gene or one microorganism for selection of host specific markers. Here, we describe the application of a genome fragment enrichment met...

  20. Genetic and host-associated differentiation within Thrips tabaci Lindeman (Thysanoptera: Thripidae) and its links to Tomato spotted wilt virus-vector competence.

    PubMed

    Westmore, G C; Poke, F S; Allen, G R; Wilson, C R

    2013-09-01

    Of eight thelytokous populations of onion thrips (Thrips tabaci) collected from potato (three populations), onion (four) or Chrysanthemum (one) hosts from various regions of Australia, only those from potato were capable of transmitting Tomato spotted wilt virus (TSWV) in controlled transmission experiments. Genetic differentiation of seven of these eight populations, and nine others not tested for TSWV vector competence, was examined by comparison of the DNA sequences of mitochondrial cytochrome oxidase subunit 1 (COI) gene. All Australian populations of T. tabaci grouped within the European 'L2' clade of Brunner et al. (2004). Within this clade the seven populations from potato, the three from onion, and the four from other hosts (Chrysanthemum, Impatiens, lucerne, blackberry nightshade) clustered as three distinct sub-groupings characterised by source host. Geographical source of thrips populations had no influence on genetic diversity. These results link genetic differentiation of thelytokous T. tabaci to source host and to TSWV vector capacity for the first time.

  1. Genetic and host-associated differentiation within Thrips tabaci Lindeman (Thysanoptera: Thripidae) and its links to Tomato spotted wilt virus-vector competence

    PubMed Central

    Westmore, G C; Poke, F S; Allen, G R; Wilson, C R

    2013-01-01

    Of eight thelytokous populations of onion thrips (Thrips tabaci) collected from potato (three populations), onion (four) or Chrysanthemum (one) hosts from various regions of Australia, only those from potato were capable of transmitting Tomato spotted wilt virus (TSWV) in controlled transmission experiments. Genetic differentiation of seven of these eight populations, and nine others not tested for TSWV vector competence, was examined by comparison of the DNA sequences of mitochondrial cytochrome oxidase subunit 1 (COI) gene. All Australian populations of T. tabaci grouped within the European ‘L2' clade of Brunner et al. (2004). Within this clade the seven populations from potato, the three from onion, and the four from other hosts (Chrysanthemum, Impatiens, lucerne, blackberry nightshade) clustered as three distinct sub-groupings characterised by source host. Geographical source of thrips populations had no influence on genetic diversity. These results link genetic differentiation of thelytokous T. tabaci to source host and to TSWV vector capacity for the first time. PMID:23632893

  2. Differences in straggling rates between two genera of dove lice (Insecta: Phthiraptera) reinforce population genetic and cophylogenetic patterns.

    PubMed

    Whiteman, Noah Kerness; Santiago-Alarcon, Diego; Johnson, Kevin P; Parker, Patricia G

    2004-09-01

    Differences in dispersal abilities have been implicated for causing disparate evolutionary patterns between Columbicola and Physconelloides lice (Insecta: Phthiraptera). However, no study has documented straggling (when lice are found on atypical hosts) rates within these lineages. We used the fact that the Galapagos Hawk, Buteo galapagoensis (Gould) (Falconiformes) feeds on the Galapagos Dove Zenaida galapagoensis Gould (Columbiformes) within an ecologically simplified setting. The Galapagos Dove is the only typical host of Columbicola macrourae (Wilson) and Physconelloides galapagensis (Kellogg and Huwana) in Galapagos. We quantitatively sampled and found these lice on both bird species. A DNA barcoding approach confirmed that stragglers were derived from Galapagos doves. We also collected a Bovicola sp. louse, likely originating from a goat (Capra hircus). On hawks, C. macrourae was significantly more prevalent than P. galapagensis. On doves, the two lice were equally prevalent and abundant. Differences in prevalence on hawks was a function of differences in straggling rate between lice, and not a reflection of their relative representation within the dove population. This provides further evidence that differences in dispersal abilities may drive differences in the degree of cospeciation in Columbicola and Phyconelloides lice, which have become model systems in evolutionary biology.

  3. Solving cryptogenic histories using host and parasite molecular genetics: the resolution of Littorina littorea's North American origin.

    PubMed

    Blakeslee, April M H; Byers, James E; Lesser, Michael P

    2008-08-01

    Even after decades of investigation using multiple sources of evidence, the natural histories of some species remain unclear (i.e. cryptogenic). A key example is Littorina littorea, the most abundant intertidal snail in northeastern North America. Native to Europe, the snail's ecological history in North America has been debated for over 100 years with no definitive resolution. To resolve its cryptogenic status, we used molecular genetics from a novel combination of the snail and a highly associated trematode parasite, Cryptocotyle lingua. Based on mitochondrial sequences of 370 L. littorea and 196 C. lingua individuals, our results demonstrate a significant reduction in genetic diversity in North America vs. Europe, North American haplotypes nested within European haplotypes, and mean divergence estimates of approxiamtely 500 years ago from Europe for both host and parasite--thus supporting a recent introduction of both host and parasite to North America from Europe. Our study therefore resolves not only a specific cryptogenic history, but it also demonstrates the success of our approach generally and could be used in resolving difficult invasion histories worldwide.

  4. When History Repeats Itself: Exploring the Genetic Architecture of Host-Plant Adaptation in Two Closely Related Lepidopteran Species

    PubMed Central

    Alexandre, Hermine; Ponsard, Sergine; Bourguet, Denis; Vitalis, Renaud; Audiot, Philippe; Cros-Arteil, Sandrine; Streiff, Réjane

    2013-01-01

    The genus Ostrinia includes two allopatric maize pests across Eurasia, namely the European corn borer (ECB, O. nubilalis) and the Asian corn borer (ACB, O. furnacalis). A third species, the Adzuki bean borer (ABB, O. scapulalis), occurs in sympatry with both the ECB and the ACB. The ABB mostly feeds on native dicots, which probably correspond to the ancestral host plant type for the genus Ostrinia. This situation offers the opportunity to characterize the two presumably independent adaptations or preadaptations to maize that occurred in the ECB and ACB. In the present study, we aimed at deciphering the genetic architecture of these two adaptations to maize, a monocot host plant recently introduced into Eurasia. To this end, we performed a genome scan analysis based on 684 AFLP markers in 12 populations of ECB, ACB and ABB. We detected 2 outlier AFLP loci when comparing French populations of the ECB and ABB, and 9 outliers when comparing Chinese populations of the ACB and ABB. These outliers were different in both countries, and we found no evidence of linkage disequilibrium between any two of them. These results suggest that adaptation or preadaptation to maize relies on a different genetic architecture in the ECB and ACB. However, this conclusion must be considered in light of the constraints inherent to genome scan approaches and of the intricate evolution of adaptation and reproductive isolation in the Ostrinia spp. complex. PMID:23874914

  5. Integrating High-Content Imaging and Chemical Genetics to Probe Host Cellular Pathways Critical for Yersinia Pestis Infection

    PubMed Central

    Kota, Krishna P.; Eaton, Brett; Lane, Douglas; Ulrich, Melanie; Ulrich, Ricky; Peyser, Brian D.; Robinson, Camenzind G.; Jaissle, James G.; Pegoraro, Gianluca; Bavari, Sina; Panchal, Rekha G.

    2013-01-01

    The molecular machinery that regulates the entry and survival of Yersinia pestis in host macrophages is poorly understood. Here, we report the development of automated high-content imaging assays to quantitate the internalization of virulent Y. pestis CO92 by macrophages and the subsequent activation of host NF-κB. Implementation of these assays in a focused chemical screen identified kinase inhibitors that inhibited both of these processes. Rac-2-ethoxy-3 octadecanamido-1-propylphosphocholine (a protein Kinase C inhibitor), wortmannin (a PI3K inhibitor), and parthenolide (an IκB kinase inhibitor), inhibited pathogen-induced NF-κB activation and reduced bacterial entry and survival within macrophages. Parthenolide inhibited NF-κB activation in response to stimulation with Pam3CSK4 (a TLR2 agonist), E. coli LPS (a TLR4 agonist) or Y. pestis infection, while the PI3K and PKC inhibitors were selective only for Y. pestis infection. Together, our results suggest that phagocytosis is the major stimulus for NF-κB activation in response to Y. pestis infection, and that Y. pestis entry into macrophages may involve the participation of protein kinases such as PI3K and PKC. More importantly, the automated image-based screening platform described here can be applied to the study of other bacteria in general and, in combination with chemical genetic screening, can be used to identify host cell functions facilitating the identification of novel antibacterial therapeutics. PMID:23383093

  6. A Cas9 Ribonucleoprotein Platform for Functional Genetic Studies of HIV-Host Interactions in Primary Human T Cells.

    PubMed

    Hultquist, Judd F; Schumann, Kathrin; Woo, Jonathan M; Manganaro, Lara; McGregor, Michael J; Doudna, Jennifer; Simon, Viviana; Krogan, Nevan J; Marson, Alexander

    2016-10-25

    New genetic tools are needed to understand the functional interactions between HIV and human host factors in primary cells. We recently developed a method to edit the genome of primary CD4(+) T cells by electroporation of CRISPR/Cas9 ribonucleoproteins (RNPs). Here, we adapted this methodology to a high-throughput platform for the efficient, arrayed editing of candidate host factors. CXCR4 or CCR5 knockout cells generated with this method are resistant to HIV infection in a tropism-dependent manner, whereas knockout of LEDGF or TNPO3 results in a tropism-independent reduction in infection. CRISPR/Cas9 RNPs can furthermore edit multiple genes simultaneously, enabling studies of interactions among multiple host and viral factors. Finally, in an arrayed screen of 45 genes associated with HIV integrase, we identified several candidate dependency/restriction factors, demonstrating the power of this approach as a discovery platform. This technology should accelerate target validation for pharmaceutical and cell-based therapies to cure HIV infection.

  7. A genetic system for Citrus Tristeza Virus using the non-natural host Nicotiana benthamiana: an update

    PubMed Central

    Ambrós, Silvia; Ruiz-Ruiz, Susana; Peña, Leandro; Moreno, Pedro

    2013-01-01

    In nature Citrus tristeza virus (CTV), genus Closterovirus, infects only the phloem cells of species of Citrus and related genera. Finding that the CTV T36 strain replicated in Nicotiana benthamiana (NB) protoplasts and produced normal virions allowed development of the first genetic system based on protoplast transfection with RNA transcribed from a full-genome cDNA clone, a laborious and uncertain system requiring several months for each experiment. We developed a more efficient system based on agroinfiltration of NB leaves with CTV-T36-based binary plasmids, which caused systemic infection in this non-natural host within a few weeks yielding in the upper leaves enough CTV virions to readily infect citrus by slash inoculation. Stem agroinoculation of citrus and NB plants with oncogenic strains of Agrobacterium tumefaciens carrying a CTV-T36 binary vector with a GUS marker, induced GUS positive galls in both species. However, while most NB tumors were CTV positive and many plants became systemically infected, no coat protein or viral RNA was detected in citrus tumors, even though CTV cDNA was readily detected by PCR in the same galls. This finding suggests (1) strong silencing or CTV RNA processing in transformed cells impairing infection progress, and (2) the need for using NB as an intermediate host in the genetic system. To maintain CTV-T36 in NB or assay other CTV genotypes in this host, we also tried to graft-transmit the virus from infected to healthy NB, or to mechanically inoculate NB leaves with virion extracts. While these trials were mostly unsuccessful on non-treated NB plants, agroinfiltration with silencing suppressors enabled for the first time infecting NB plants by side-grafting and by mechanical inoculation with virions, indicating that previous failure to infect NB was likely due to virus silencing in early infection steps. Using NB as a CTV host provides new possibilities to study virus-host interactions with a simple and reliable system. PMID

  8. Ecology of hantaviruses in Mexico: genetic identification of rodent host species and spillover infection.

    PubMed

    Saasa, Ngonda; Sánchez-Hernández, Cornelio; de Lourdes Romero-Almaraz, María; Guerrero-Ibarra, Ezequiel; Almazán-Catalán, Alberto; Yoshida, Haruka; Miyashita, Daisuke; Ishizuka, Mariko; Sanada, Takahiro; Seto, Takahiro; Yoshii, Kentaro; Ramos, Celso; Yoshimatsu, Kumiko; Arikawa, Jiro; Takashima, Ikuo; Kariwa, Hiroaki

    2012-09-01

    In our recent epidemiological survey conducted in Mexico for hantavirus infection, we identified three distinct viruses circulating in Mexican wild rodents, namely Montano virus (MTNV), Huitzilac virus (HUIV), and Carrizal virus (CARV). To gain a detailed understanding of hantavirus epidemiology and its associated hosts, 410 rodents were captured at eight collecting points in Morelos and Guerrero, Mexico, and examined for hantavirus seroprevalence, the presence of viral RNA, and rodent host species identification using cytochrome b gene sequences. Of the 32 species captured, seven species were positive for hantavirus: Peromyscus beatae (31/127; 24.4%), Reithrodontomys sumichrasti (6/15; 40%), Reithrodontomys megalotis (2/25; 8%), Peromyscus aztecus evides (1/1; 100%), Peromyscus megalops (1/41; 2.4%), Megadontomys thomasi (1/9; 11.1%), and Neotoma picta (1/6; 16.7%), with an overall prevalence of 10.5%; virus genome persisted in the majority of seropositive rodents. Nucleotide sequence and phylogenetic analysis showed that the viruses belonged mainly to the three lineages previously identified. The data showed that MTNV and CARV were primarily carried by P. beatae and R. sumichrasti, respectively. In addition, the data revealed an apparent complex interaction between hantaviruses and their hosts, suggesting active transmission and/or spillover infections within sympatric rodent species.

  9. Genetic structure of Aegilops cylindrica Host in its native range and in the United States of America.

    PubMed

    Gandhi, Harish T; Vales, M Isabel; Mallory-Smith, Carol; Riera-Lizarazu, Oscar

    2009-10-01

    Chloroplast and nuclear microsatellite markers were used to study genetic diversity and genetic structure of Aegilops cylindrica Host collected in its native range and in adventive sites in the USA. Our analysis suggests that Ae. cylindrica, an allotetraploid, arose from multiple hybridizations between Ae. markgrafii (Greuter) Hammer. and Ae. tauschii Coss. presumably along the Fertile Crescent, where the geographic distributions of its diploid progenitors overlap. However, the center of genetic diversity of this species now encompasses a larger area including northern Iraq, eastern Turkey, and Transcaucasia. Although the majority of accessions of Ae. cylindrica (87%) had D-type plastomes derived from Ae. tauschii, accessions with C-type plastomes (13%), derived from Ae. markgrafii, were also observed. This corroborates a previous study suggesting the dimaternal origin of Ae. cylindrica. Model-based and genetic distance-based clustering using both chloroplast and nuclear markers indicated that Ae. tauschii ssp. tauschii contributed one of its D-type plastomes and its D genome to Ae. cylindrica. Analysis of genetic structure using nuclear markers suggested that Ae. cylindrica accessions could be grouped into three subpopulations (arbitrarily named N-K1, N-K2, and N-K3). Members of the N-K1 subpopulation were the most numerous in its native range and members of the N-K2 subpopulation were the most common in the USA. Our analysis also indicated that Ae. cylindrica accessions in the USA were derived from a few founder genotypes. The frequency of Ae. cylindrica accessions with the C-type plastome in the USA (approximately 24%) was substantially higher than in its native range of distribution (approximately 3%) and all C-type Ae. cylindrica in the USA except one belonged to subpopulation N-K2. The high frequency of the C-type plastome in the USA may reflect a favorable nucleo-cytoplasmic combination.

  10. Environmental Mapping of Paracoccidioides spp. in Brazil Reveals New Clues into Genetic Diversity, Biogeography and Wild Host Association

    PubMed Central

    Arantes, Thales Domingos; Theodoro, Raquel Cordeiro; Teixeira, Marcus de Melo; Bosco, Sandra de Moraes Gimenes; Bagagli, Eduardo

    2016-01-01

    Background Paracoccidioides brasiliensis and Paracoccidioides lutzii are the etiological agents of Paracoccidioidomycosis (PCM), and are easily isolated from human patients. However, due to human migration and a long latency period, clinical isolates do not reflect the spatial distribution of these pathogens. Molecular detection of P. brasiliensis and P. lutzii from soil, as well as their isolation from wild animals such as armadillos, are important for monitoring their environmental and geographical distribution. This study aimed to detect and, for the first time, evaluate the genetic diversity of P. brasiliensis and P. lutzii for Paracoccidioidomycosis in endemic and non-endemic areas of the environment, by using Nested PCR and in situ hybridization techniques. Methods/Principal Findings Aerosol (n = 16) and soil (n = 34) samples from armadillo burrows, as well as armadillos (n = 7) were collected in endemic and non-endemic areas of PCM in the Southeastern, Midwestern and Northern regions of Brazil. Both P. brasiliensis and P. lutzii were detected in soil (67.5%) and aerosols (81%) by PCR of Internal Transcribed Spacer (ITS) region (60%), and also by in situ hybridization (83%). Fungal isolation from armadillo tissues was not possible. Sequences from both species of P. brasiliensis and P. lutzii were detected in all regions. In addition, we identified genetic Paracoccidioides variants in soil and aerosol samples which have never been reported before in clinical or armadillo samples, suggesting greater genetic variability in the environment than in vertebrate hosts. Conclusions/Significance Data may reflect the actual occurrence of Paracoccidioides species in their saprobic habitat, despite their absence/non-detection in seven armadillos evaluated in regions with high prevalence of PCM infection by P. lutzii. These results may indicate a possible ecological difference between P. brasiliensis and P. lutzii concerning their wild hosts. PMID:27045486

  11. IMPROVING PLANT GENETIC ENGINEERING BY MANIPULATING THE HOST. (R829479C001)

    EPA Science Inventory

    Agrobacterium-mediated transformation is a major technique for the genetic engineering of plants. However, there are many economically important crop and tree species that remain highly recalcitrant to Agrobacterium infection. Although attempts have been made to ...

  12. Genetic tool development for a new host for biotechnology, the thermotolerant bacterium Bacillus coagulans.

    PubMed

    Kovács, Akos T; van Hartskamp, Mariska; Kuipers, Oscar P; van Kranenburg, Richard

    2010-06-01

    Bacillus coagulans has good potential as an industrial production organism for platform chemicals from renewable resources but has limited genetic tools available. Here, we present a targeted gene disruption system using the Cre-lox system, development of a LacZ reporter assay for monitoring gene transcription, and heterologous d-lactate dehydrogenase expression.

  13. Comparative genomics of Campylobacter iguaniorum to unravel genetic regions associated with reptilian hosts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Campylobacter iguaniorum is genetically related to the species C. fetus, C. hyointestinalis, and C. lanienae. Reptiles, chelonians and lizards in particular, appear to be the primary reservoir of this Campylobacter species. Here we report the genome comparison of C. iguaniorum strain 1485E, isolated...

  14. Genetic Variability of Stolbur Phytoplasma in Hyalesthes obsoletus (Hemiptera: Cixiidae) and its Main Host Plants in Vineyard Agroecosystems.

    PubMed

    Landi, Lucia; Riolo, Paola; Murolo, Sergio; Romanazzi, Gianfranco; Nardi, Sandro; Isidoro, Nunzio

    2015-08-01

    Bois noir is an economically important grapevine yellows that is induced by 'Candidatus Phytoplasma solani' and principally vectored by the planthopper Hyalesthes obsoletus Signoret (Hemiptera: Cixiidae). This study explores the 'Ca. P. solani' genetic variability associated to the nettle-H. obsoletus and bindweed-H. obsoletus systems in vineyard agroecosystems of the central-eastern Italy. Molecular characterization of 'Ca. P. solani' isolates was carried out using polymerase chain reaction/restriction fragment length polymorphism to investigate the nonribosomal vmp1 gene. Seven phytoplasma vmp-types were detected among the host plants- and insect-associated field-collected samples. The vmp1 gene showed the highest polymorphism in the bindweed-H. obsoletus system, according to restriction fragment length polymorphism analysis, which is in agreement with nucleotide sequence analysis. Five vmp-types were associated with H. obsoletus from bindweed, of which one was solely restricted to planthoppers, with one genotype also in planthoppers from nettle. Type V12 was the most prevalent in both planthoppers and bindweed. H. obsoletus from nettle harbored three vmp-types, of which V3 was predominant. V3 was the only type detected for nettle. Our data demonstrate that planthoppers might have acquired some 'Ca. P. solani' profiles from other plant hosts before landing on nettle or bindweed. Overall, the different vmp1 gene rearrangements observed in these two plant hosts-H. obsoletus systems might represent different adaptations of the pathogen to the two host plants. Molecular information about the complex of vmp-types provides useful data for better understanding of Bois noir epidemiology in vineyard agroecosystem.

  15. The Genetic Architecture of a Complex Ecological Trait: Host Plant Use in the Specialist Moth, Heliothis subflexa

    PubMed Central

    Oppenheim, Sara J.; Gould, Fred; Hopper, Keith R.

    2012-01-01

    We used genetic mapping to examine the genetic architecture of differences in host plant use between two species of noctuid moths, Heliothis subflexa, a specialist on Physalis spp., and its close relative, the broad generalist H. virescens. We introgressed H. subflexa chromosomes into the H. virescens background and analyzed 1,462 backcross insects. The effects of H. subflexa-origin chromosomes were small when measured as the percent variation explained in backcross populations (0.2 to 5%), but were larger when considered in relation to the interspecific difference explained (1.5 to 165%). Most significant chromosomes had effects on more than one trait, and their effects varied between years, sexes, and genetic backgrounds. Different chromosomes could produce similar phenotypes, suggesting that the same trait might be controlled by different chromosomes in different backcross populations. It appears that many loci of small effect contribute to the use of Physalis by H. subflexa. We hypothesize that behavioral changes may have paved the way for physiological adaptation to Physalis by the generalist ancestor of H. subflexa and H. virescens. PMID:23106701

  16. The Interplay Between Host Genetic Variation, Viral Replication, and Microbial Translocation in Untreated HIV-Infected Individuals

    PubMed Central

    Perkins, Molly R.; Bartha, Istvan; Timmer, J. Katherina; Liebner, Julia C.; Wollinsky, David; Günthard, Huldrych F.; Hauser, Christoph; Bernasconi, Enos; Hoffmann, Matthias; Calmy, Alexandra; Battegay, Manuel; Telenti, Amalio; Douek, Daniel C.; Fellay, Jacques; Aubert, V.; Battegay, M.; Bernasconi, E.; Böni, J.; Bucher, H.C.; Burton-Jeangros, C.; Calmy, A.; Cavassini, M.; Dollenmaier, G.; Egger, M.; Elzi, L.; Fehr, J.; Fellay, J.; Furrer, H.; Fux, C.A.; Gorgievski, M.; Günthard, H.; Haerry, D.; Hasse, B.; Hirsch, H.H.; Hoffmann, M.; Hösli, I.; Kahlert, C.; Kaiser, L.; Keiser, O.; Klimkait, T.; Kouyos, R.; Kovari, H.; Ledergerber, B.; Martinetti, G.; Martinez de Tejada, B.; Metzner, K.; Müller, N.; Nadal, D.; Nicca, D.; Pantaleo, G.; Rauch, A.; Regenass, S.; Rickenbach, M.; Rudin, C.; Schöni-Affolter, F.; Schmid, P.; Schüpbach, J.; Speck, R.; Tarr, P.; Telenti, A.; Trkola, A.; Vernazza, P.; Weber, R.; Yerly, S.

    2015-01-01

    Systemic immune activation, a major determinant of human immunodeficiency virus (HIV) disease progression, is the result of a complex interplay between viral replication, dysregulation of the immune system, and microbial translocation due to gut mucosal damage. Although human genetic variants influencing HIV load have been identified, it is unknown how much the host genetic background contributes to interindividual differences in other determinants of HIV pathogenesis such as gut damage and microbial translocation. Using samples and data from 717 untreated participants in the Swiss HIV Cohort Study and a genome-wide association study design, we searched for human genetic determinants of plasma levels of intestinal fatty acid–binding protein (I-FABP/FABP2), a marker of gut damage, and of soluble CD14 (sCD14), a marker of lipopolysaccharide bioactivity and microbial translocation. We also assessed the correlations between HIV load, sCD14, and I-FABP. Although we found no genome-wide significant determinant of the tested plasma markers, we observed strong associations between sCD14 and both HIV load and I-FABP, shedding new light on the relationships between processes that drive progression of untreated HIV infection. PMID:25701868

  17. Genetic diversity and host specificity varies across three genera of blood parasites in ducks of the Pacific Americas Flyway

    USGS Publications Warehouse

    Reeves, Andrew B.; Smith, Matthew M.; Meixell, Brandt W.; Fleskes, Joseph P.; Ramey, Andrew M.

    2015-01-01

    Birds of the order Anseriformes, commonly referred to as waterfowl, are frequently infected by Haemosporidia of the genera Haemoproteus, Plasmodium, and Leucocytozoon via dipteran vectors. We analyzed nucleotide sequences of the Cytochrome b (Cytb) gene from parasites of these genera detected in six species of ducks from Alaska and California, USA to characterize the genetic diversity of Haemosporidia infecting waterfowl at two ends of the Pacific Americas Flyway. In addition, parasite Cytb sequences were compared to those available on a public database to investigate specificity of genetic lineages to hosts of the order Anseriformes. Haplotype and nucleotide diversity of Haemoproteus Cytb sequences was lower than was detected for Plasmodium and Leucocytozoon parasites. Although waterfowl are presumed to be infected by only a single species of Leucocytozoon, L. simondi, diversity indices were highest for haplotypes from this genus and sequences formed five distinct clades separated by genetic distances of 4.9%–7.6%, suggesting potential cryptic speciation. All Haemoproteus andLeucocytozoon haplotypes derived from waterfowl samples formed monophyletic clades in phylogenetic analyses and were unique to the order Anseriformes with few exceptions. In contrast, waterfowl-origin Plasmodium haplotypes were identical or closely related to lineages found in other avian orders. Our results suggest a more generalist strategy for Plasmodiumparasites infecting North American waterfowl as compared to those of the generaHaemoproteus and Leucocytozoon.

  18. No Major Host Genetic Risk Factor Contributed to A(H1N1)2009 Influenza Severity

    PubMed Central

    Garcia-Etxebarria, Koldo; Bracho, María Alma; Galán, Juan Carlos; Pumarola, Tomàs; Castilla, Jesús; Ortiz de Lejarazu, Raúl; Rodríguez-Dominguez, Mario; Quintela, Inés; Bonet, Núria; Garcia-Garcerà, Marc; Domínguez, Angela; González-Candelas, Fernando; Calafell, Francesc

    2015-01-01

    While most patients affected by the influenza A(H1N1) pandemic experienced mild symptoms, a small fraction required hospitalization, often without concomitant factors that could explain such a severe course. We hypothesize that host genetic factors could contribute to aggravate the disease. To test this hypothesis, we compared the allele frequencies of 547,296 genome-wide single nucleotide polymorphisms (SNPs) between 49 severe and 107 mild confirmed influenza A cases, as well as against a general population sample of 549 individuals. When comparing severe vs. mild influenza A cases, only one SNP was close to the conventional p = 5×10−8. This SNP, rs28454025, sits in an intron of the GSK233 gene, which is involved in a neural development, but seems not to have any connections with immunological or inflammatory functions. Indirectly, a previous association reported with CD55 was replicated. Although sample sizes are low, we show that the statistical power in our design was sufficient to detect highly-penetrant, quasi-Mendelian genetic factors. Hence, and assuming that rs28454025 is likely to be a false positive, no major genetic factor was detected that could explain poor influenza A course. PMID:26379185

  19. Genetic Diversity and Host Specificity Varies across Three Genera of Blood Parasites in Ducks of the Pacific Americas Flyway

    PubMed Central

    Reeves, Andrew B.; Smith, Mathew M.; Meixell, Brandt W.; Fleskes, Joseph P; Ramey, Andrew M.

    2015-01-01

    Birds of the order Anseriformes, commonly referred to as waterfowl, are frequently infected by Haemosporidia of the genera Haemoproteus, Plasmodium, and Leucocytozoon via dipteran vectors. We analyzed nucleotide sequences of the Cytochrome b (Cytb) gene from parasites of these genera detected in six species of ducks from Alaska and California, USA to characterize the genetic diversity of Haemosporidia infecting waterfowl at two ends of the Pacific Americas Flyway. In addition, parasite Cytb sequences were compared to those available on a public database to investigate specificity of genetic lineages to hosts of the order Anseriformes. Haplotype and nucleotide diversity of Haemoproteus Cytb sequences was lower than was detected for Plasmodium and Leucocytozoon parasites. Although waterfowl are presumed to be infected by only a single species of Leucocytozoon, L. simondi, diversity indices were highest for haplotypes from this genus and sequences formed five distinct clades separated by genetic distances of 4.9%–7.6%, suggesting potential cryptic speciation. All Haemoproteus and Leucocytozoon haplotypes derived from waterfowl samples formed monophyletic clades in phylogenetic analyses and were unique to the order Anseriformes with few exceptions. In contrast, waterfowl-origin Plasmodium haplotypes were identical or closely related to lineages found in other avian orders. Our results suggest a more generalist strategy for Plasmodium parasites infecting North American waterfowl as compared to those of the genera Haemoproteus and Leucocytozoon. PMID:25710468

  20. The host genetic background defines diverse immune-reactivity and susceptibility to chronic Pseudomonas aeruginosa respiratory infection

    PubMed Central

    Spagnuolo, Lorenza; Simone, Maura De; Lorè, Nicola Ivan; Fino, Ida De; Basso, Veronica; Mondino, Anna; Cigana, Cristina; Bragonzi, Alessandra

    2016-01-01

    Patients with P. aeruginosa airways infection show markedly variable clinical phenotypes likely influenced by genetic backgrounds. Here, we investigated the cellular events involved in resistance and susceptibility to P. aeruginosa chronic infection using genetically distinct inbred mouse strains. As for patients, different murine genotypes revealed variable susceptibility to infection. When directly compared, resistant C3H/HeOuJ and susceptible A/J strains revealed distinct immune responsiveness to the pathogen. In C3H/HeOuJ resistant mice, IL17-producing cells rapidly and transiently infiltrated the infected lung, and this was paralleled by the acute accumulation of alveolar macrophages, bacterial clearance and resolution of infection. In contrast, A/J susceptible mice revealed a more delayed and prolonged lung infiltration by IL17+ and IFNγ+ cells, persistence of innate inflammatory cells and establishment of chronic infection. We conclude that the host genetic background confers diverse immunoreactivity to P. aeruginosa and IL17-producing cells might contribute to the progress of chronic lung infection. PMID:27848994

  1. Fine-scale genetic analysis of Daphnia host populations infected by two virulent parasites - strong fluctuations in clonal structure at small temporal and spatial scales.

    PubMed

    Yin, Mingbo; Petrusek, Adam; Seda, Jaromir; Wolinska, Justyna

    2012-01-01

    Numerous theoretical studies suggest that parasites impose a strong selection pressure on their host, driving genetic changes within host populations. Yet evidence of this process in the wild is scarce. In the present study we surveyed, using high resolution microsatellite markers, the genetic structure of cyclically parthenogenetic Daphnia hosts within two different Daphnia communities belonging to the Daphnia longispina hybrid complex. One community, consisting of a single host species, was infected with the protozoan parasite Caullerya mesnili. The second community consisted of two parental Daphnia spp. and their hybrids, and was infected with the yeast parasite Metschnikowia. Significant differences in the clonal composition between random and infected sub-samples of Daphnia were detected on several occasions within both communities, indicating that host genotypes differ in resistance to both parasites. In addition, one parental species in the multi-taxon community was consistently under-infected, compared with the other taxa. Overall, our field data confirm that infection patterns are strongly affected by host genetic composition in various Daphnia-microparasite systems. Thus, parasite-driven selection operates in natural Daphnia populations and microparasites influence the clonal structure of host populations.

  2. Spatio-temporal Analysis of the Genetic Diversity of Arctic Rabies Viruses and Their Reservoir Hosts in Greenland

    PubMed Central

    Hanke, Dennis; Freuling, Conrad M.; Fischer, Susanne; Hueffer, Karsten; Hundertmark, Kris; Nadin-Davis, Susan; Marston, Denise; Fooks, Anthony R.; Bøtner, Anette; Mettenleiter, Thomas C.; Beer, Martin; Rasmussen, Thomas B.; Müller, Thomas F.; Höper, Dirk

    2016-01-01

    There has been limited knowledge on spatio-temporal epidemiology of zoonotic arctic fox rabies among countries bordering the Arctic, in particular Greenland. Previous molecular epidemiological studies have suggested the occurrence of one particular arctic rabies virus (RABV) lineage (arctic-3), but have been limited by a low number of available samples preventing in-depth high resolution phylogenetic analysis of RABVs at that time. However, an improved knowledge of the evolution, at a molecular level, of the circulating RABVs and a better understanding of the historical perspective of the disease in Greenland is necessary for better direct control measures on the island. These issues have been addressed by investigating the spatio-temporal genetic diversity of arctic RABVs and their reservoir host, the arctic fox, in Greenland using both full and partial genome sequences. Using a unique set of 79 arctic RABV full genome sequences from Greenland, Canada, USA (Alaska) and Russia obtained between 1977 and 2014, a description of the historic context in relation to the genetic diversity of currently circulating RABV in Greenland and neighboring Canadian Northern territories has been provided. The phylogenetic analysis confirmed delineation into four major arctic RABV lineages (arctic 1–4) with viruses from Greenland exclusively grouping into the circumpolar arctic-3 lineage. High resolution analysis enabled distinction of seven geographically distinct subclades (3.I – 3.VII) with two subclades containing viruses from both Greenland and Canada. By combining analysis of full length RABV genome sequences and host derived sequences encoding mitochondrial proteins obtained simultaneously from brain tissues of 49 arctic foxes, the interaction of viruses and their hosts was explored in detail. Such an approach can serve as a blueprint for analysis of infectious disease dynamics and virus-host interdependencies. The results showed a fine-scale spatial population structure

  3. Spatio-temporal Analysis of the Genetic Diversity of Arctic Rabies Viruses and Their Reservoir Hosts in Greenland.

    PubMed

    Hanke, Dennis; Freuling, Conrad M; Fischer, Susanne; Hueffer, Karsten; Hundertmark, Kris; Nadin-Davis, Susan; Marston, Denise; Fooks, Anthony R; Bøtner, Anette; Mettenleiter, Thomas C; Beer, Martin; Rasmussen, Thomas B; Müller, Thomas F; Höper, Dirk

    2016-07-01

    There has been limited knowledge on spatio-temporal epidemiology of zoonotic arctic fox rabies among countries bordering the Arctic, in particular Greenland. Previous molecular epidemiological studies have suggested the occurrence of one particular arctic rabies virus (RABV) lineage (arctic-3), but have been limited by a low number of available samples preventing in-depth high resolution phylogenetic analysis of RABVs at that time. However, an improved knowledge of the evolution, at a molecular level, of the circulating RABVs and a better understanding of the historical perspective of the disease in Greenland is necessary for better direct control measures on the island. These issues have been addressed by investigating the spatio-temporal genetic diversity of arctic RABVs and their reservoir host, the arctic fox, in Greenland using both full and partial genome sequences. Using a unique set of 79 arctic RABV full genome sequences from Greenland, Canada, USA (Alaska) and Russia obtained between 1977 and 2014, a description of the historic context in relation to the genetic diversity of currently circulating RABV in Greenland and neighboring Canadian Northern territories has been provided. The phylogenetic analysis confirmed delineation into four major arctic RABV lineages (arctic 1-4) with viruses from Greenland exclusively grouping into the circumpolar arctic-3 lineage. High resolution analysis enabled distinction of seven geographically distinct subclades (3.I - 3.VII) with two subclades containing viruses from both Greenland and Canada. By combining analysis of full length RABV genome sequences and host derived sequences encoding mitochondrial proteins obtained simultaneously from brain tissues of 49 arctic foxes, the interaction of viruses and their hosts was explored in detail. Such an approach can serve as a blueprint for analysis of infectious disease dynamics and virus-host interdependencies. The results showed a fine-scale spatial population structure in

  4. New hosts and genetic diversity of Flavobacterium columnare isolated from Brazilian native species and Nile tilapia.

    PubMed

    Barony, G M; Tavares, G C; Assis, G B N; Luz, R K; Figueiredo, H C P; Leal, C A G

    2015-11-17

    Flavobacterium columnare is responsible for disease outbreaks in freshwater fish farms. Several Brazilian native fish have been commercially exploited or studied for aquaculture purposes, including Amazon catfish Leiarius marmoratus × Pseudoplatystoma fasciatum and pacamã Lophiosilurus alexandri. This study aimed to identify the aetiology of disease outbreaks in Amazon catfish and pacamã hatcheries and to address the genetic diversity of F. columnare isolates obtained from diseased fish. Two outbreaks in Amazon catfish and pacamã hatcheries took place in 2010 and 2011. Four F. columnare strains were isolated from these fish and identified by PCR. The disease was successfully reproduced under experimental conditions for both fish species, fulfilling Koch's postulates. The genomovar of these 4 isolates and of an additional 11 isolates from Nile tilapia Oreochromis niloticus was determined by 16S rRNA restriction fragment length polymorphism PCR. The genetic diversity was evaluated by phylogenetic analysis of the 16S rRNA gene and repetitive extragenic palindromic PCR (REP-PCR). Most isolates (n = 13) belonged to genomovar II; the remaining 2 isolates (both from Nile tilapia) were assigned to genomovar I. Phylogenetic analysis and REP-PCR were able to demonstrate intragenomovar diversity. This is the first report of columnaris in Brazilian native Amazon catfish and pacamã. The Brazilian F. columnare isolates showed moderate diversity, and REP-PCR was demonstrated to be a feasible method to evaluate genetic variability in this bacterium.

  5. Establishment of a genetically marked insect-derived symbiont in multiple host plants.

    PubMed

    Bextine, Blake; Lampe, David; Lauzon, Carol; Jackson, Brian; Miller, Thomas A

    2005-01-01

    Alcaligenes xylosoxidans subsp. denitrificans, originally isolated from the cibarial region of the foregut of the glassy-winged sharpshooter (Homalodisca coagulata), was transformed using the Himar1 transposition system to express EGFP. Seedlings of six potential host plants were inoculated with transformed bacteria and 2 weeks later samples were taken 5 cm away and analyzed by quantitative real-time PCR using primers designed to amplify the gene insert. The largest colony of 3,591,427 cells/2 cm of A. xylosoxidans subsp. denitrificans was found in Citrus limon, with almost all plants testing positive in both trials. The amount of colonization decreased in the other plants tested in the following order: orange (Citrus sinensis "sweet orange") > chrysanthemum (Chrysanthemum grandiflora cv. "White Diamond") > periwinkle (Vinca rosea) > crepe myrtle (Lagerstroemia indica) > grapevine (Vitis vinifera cv. Chardonnay). The bacterium's preference for citrus paralleled the host insect's preference for this same plant. Additional tests determined that A. xylosoxidans subsp. denitrificans thrives as a nonpathogenic, xylem-associated endophyte.

  6. Comparative Genomics of Campylobacter iguaniorum to Unravel Genetic Regions Associated with Reptilian Hosts.

    PubMed

    Gilbert, Maarten J; Miller, William G; Yee, Emma; Kik, Marja; Zomer, Aldert L; Wagenaar, Jaap A; Duim, Birgitta

    2016-10-05

    Campylobacter iguaniorum is most closely related to the species C fetus, C hyointestinalis, and C lanienae Reptiles, chelonians and lizards in particular, appear to be a primary reservoir of this Campylobacter species. Here we report the genome comparison of C iguaniorum strain 1485E, isolated from a bearded dragon (Pogona vitticeps), and strain 2463D, isolated from a green iguana (Iguana iguana), with the genomes of closely related taxa, in particular with reptile-associated C fetus subsp. testudinum In contrast to C fetus, C iguaniorum is lacking an S-layer encoding region. Furthermore, a defined lipooligosaccharide biosynthesis locus, encoding multiple glycosyltransferases and bounded by waa genes, is absent from C iguaniorum Instead, multiple predicted glycosylation regions were identified in C iguaniorum One of these regions is > 50 kb with deviant G + C content, suggesting acquisition via lateral transfer. These similar, but non-homologous glycosylation regions were located at the same position on the genome in both strains. Multiple genes encoding respiratory enzymes not identified to date within the C. fetus clade were present. C iguaniorum shared highest homology with C hyointestinalis and C fetus. As in reptile-associated C fetus subsp. testudinum, a putative tricarballylate catabolism locus was identified. However, despite colonizing a shared host, no recent recombination between both taxa was detected. This genomic study provides a better understanding of host adaptation, virulence, phylogeny, and evolution of C iguaniorum and related Campylobacter taxa.

  7. Lack of population genetic structure and host specificity in the bat fly, Cyclopodia horsfieldi, across species of Pteropus bats in Southeast Asia

    PubMed Central

    2013-01-01

    Background Population-level studies of parasites have the potential to elucidate patterns of host movement and cross-species interactions that are not evident from host genealogy alone. Bat flies are obligate and generally host-specific blood-feeding parasites of bats. Old-World flies in the family Nycteribiidae are entirely wingless and depend on their hosts for long-distance dispersal; their population genetics has been unstudied to date. Methods We collected a total of 125 bat flies from three Pteropus species (Pteropus vampyrus, P. hypomelanus, and P. lylei) from eight localities in Malaysia, Cambodia, and Vietnam. We identified specimens morphologically and then sequenced three mitochondrial DNA gene fragments (CoI, CoII, cytB; 1744 basepairs total) from a subset of 45 bat flies. We measured genetic diversity, molecular variance, and population genetic subdivision (FST), and used phylogenetic and haplotype network analyses to quantify parasite genetic structure across host species and localities. Results All flies were identified as Cyclopodia horsfieldi with the exception of two individuals of Eucampsipoda sundaica. Low levels of population genetic structure were detected between populations of Cyclopodia horsfieldi from across a wide geographic range (~1000 km), and tests for isolation by distance were rejected. AMOVA results support a lack of geographic and host-specific population structure, with molecular variance primarily partitioned within populations. Pairwise FST values from flies collected from island populations of Pteropus hypomelanus in East and West Peninsular Malaysia supported predictions based on previous studies of host genetic structure. Conclusions The lack of population genetic structure and morphological variation observed in Cyclopodia horsfieldi is most likely due to frequent contact between flying fox species and subsequent high levels of parasite gene flow. Specifically, we suggest that Pteropus vampyrus may facilitate movement of

  8. Virus-induced diabetes mellitus. VI. Genetically determined host differences in the replicating of encephalomyocarditis virus in pancreatic beta cells

    PubMed Central

    1976-01-01

    Beta cells were isolated from strains of mice that were susceptible and resistant to encephalomyocarditis (EMC) viral-induced diabetes mellitus. Beta cells from susceptible mice that were infected in vivo with EMC virus showed higher viral titers, more severe degranulation, and lower concentrations of immunoreactive insulin than beta cells from resistant mice. Immunofluorescence and infectious center assays revealed that pancreas from susceptible mice contained at least 10 times more infected cells than pancreas from resistant mice. Beta cell cultures prepared from susceptible mice and infected in vitro also showed higher viral titers and more severe cytopathologic changes than beta cell cultures from resistant mice. In contrast to beta cell cultures, virus replicated equally well in primary embryo and kidney cell cultures from susceptible and resistant strains of mice. It is concluded that the development of EMC virus-induced diabetes is related to genetically determined host differences in the capacity of the virus to infect beta cells. PMID:177713

  9. Helicobacter pylori virulence genes and host genetic polymorphisms as risk factors for peptic ulcer disease.

    PubMed

    Miftahussurur, Muhammad; Yamaoka, Yoshio

    2015-01-01

    Helicobacter pylori infection plays an important role in the pathogenesis of peptic ulcer disease (PUD). Several factors have been proposed as possible H. pylori virulence determinants; for example, bacterial adhesins and gastric inflammation factors are associated with an increased risk of PUD. However, differences in bacterial virulence factors alone cannot explain the opposite ends of the PUD disease spectrum, that is duodenal and gastric ulcers; presumably, both bacterial and host factors contribute to the differential response. Carriers of the high-producer alleles of the pro-inflammatory cytokines IL-1B, IL-6, IL-8, IL-10, and TNF-α who also carry low-producer allele of anti-inflammatory cytokines have severe gastric mucosal inflammation, whereas carriers of the alternative alleles have mild inflammation. Recent reports have suggested that the PSCA and CYP2C19 ultra-rapid metabolizer genotypes are also associated with PUD.

  10. Helicobacter pylori virulence genes and host genetic polymorphisms as risk factors for peptic ulcer disease

    PubMed Central

    Yamaoka, Yoshio; Miftahussurur, Muhammad

    2017-01-01

    Helicobacter pylori infection plays an important role in the pathogenesis of peptic ulcer disease (PUD). Several factors have been proposed as possible H. pylori virulence determinants; for example, bacterial adhesins and gastric inflammation factors are associated with an increased risk of PUD. However, differences in bacterial virulence factors alone cannot explain the opposite ends of the PUD disease spectrum, i.e., duodenal and gastric ulcers; presumably, both bacterial and host factors contribute to the differential response. Carriers of the high-producer alleles of the pro-inflammatory cytokines interleukin (IL)-1B, IL-6, IL-8, IL-10, and tumor necrosis factor-α who also carry low-producer allele carriers of anti-inflammatory cytokines have severe gastric mucosal inflammation, whereas carriers of the alternative alleles have mild inflammation. Recent reports have suggested that the PSCA and CYP2C19 ultra-rapid metabolizer genotypes are also associated with PUD. PMID:26470920

  11. Genetic and environmental factors affecting host response to drugs and other chemical compounds in our environment.

    PubMed Central

    Vesell, E S; Passananti, G T

    1977-01-01

    Compared to laboratory animals, humans are extremely heterogenous with respect to the many factors that can influence the distribution and biological effects of toxic chemicals. This heterogeneity can prevent an accurate assessment of the impact of a particular toxic compound on the health of an individual subject. Some of the factors that can significantly modify the host response to certain drugs, which serve in this review as a model for environmental chemicals, are enumerated and discussed. Although the mechanisms by which many of these factors modify the biological effects of certain environmental chemicals and drugs have been determined in some cases, better definition of the nature of interactions between these factors and environmental chemicals in a particular individual is required at a biochemical and molecular level. Recommendations are offered for the further development of our knowledge concerning interactions between environmental chemicals and such factors in a particular individual. PMID:598349

  12. Bacterial host and reporter gene optimization for genetically encoded whole cell biosensors.

    PubMed

    Brutesco, Catherine; Prévéral, Sandra; Escoffier, Camille; Descamps, Elodie C T; Prudent, Elsa; Cayron, Julien; Dumas, Louis; Ricquebourg, Manon; Adryanczyk-Perrier, Géraldine; de Groot, Arjan; Garcia, Daniel; Rodrigue, Agnès; Pignol, David; Ginet, Nicolas

    2017-01-01

    Whole-cell biosensors based on reporter genes allow detection of toxic metals in water with high selectivity and sensitivity under laboratory conditions; nevertheless, their transfer to a commercial inline water analyzer requires specific adaptation and optimization to field conditions as well as economical considerations. We focused here on both the influence of the bacterial host and the choice of the reporter gene by following the responses of global toxicity biosensors based on constitutive bacterial promoters as well as arsenite biosensors based on the arsenite-inducible Pars promoter. We observed important variations of the bioluminescence emission levels in five different Escherichia coli strains harboring two different lux-based biosensors, suggesting that the best host strain has to be empirically selected for each new biosensor under construction. We also investigated the bioluminescence reporter gene system transferred into Deinococcus deserti, an environmental, desiccation- and radiation-tolerant bacterium that would reduce the manufacturing costs of bacterial biosensors for commercial water analyzers and open the field of biodetection in radioactive environments. We thus successfully obtained a cell survival biosensor and a metal biosensor able to detect a concentration as low as 100 nM of arsenite in D. deserti. We demonstrated that the arsenite biosensor resisted desiccation and remained functional after 7 days stored in air-dried D. deserti cells. We also report here the use of a new near-infrared (NIR) fluorescent reporter candidate, a bacteriophytochrome from the magnetotactic bacterium Magnetospirillum magneticum AMB-1, which showed a NIR fluorescent signal that remained optimal despite increasing sample turbidity, while in similar conditions, a drastic loss of the lux-based biosensors signal was observed.

  13. Host Genetics and Environment Drive Divergent Responses of Two Resource Sharing Gall-Formers on Norway Spruce: A Common Garden Analysis.

    PubMed

    Axelsson, E Petter; Iason, Glenn R; Julkunen-Tiitto, Riitta; Whitham, Thomas G

    2015-01-01

    A central issue in the field of community genetics is the expectation that trait variation among genotypes play a defining role in structuring associated species and in forming community phenotypes. Quantifying the existence of such community phenotypes in two common garden environments also has important consequences for our understanding of gene-by-environment interactions at the community level. The existence of community phenotypes has not been evaluated in the crowns of boreal forest trees. In this study we address the influence of tree genetics on needle chemistry and genetic x environment interactions on two gall-inducing adelgid aphids (Adelges spp. and Sacchiphantes spp.) that share the same elongating bud/shoot niche. We examine the hypothesis that the canopies of different genotypes of Norway spruce (Picea abies L.) support different community phenotypes. Three patterns emerged. First, the two gallers show clear differences in their response to host genetics and environment. Whereas genetics significantly affected the abundance of Adelges spp. galls, Sacchiphantes spp. was predominately affected by the environment suggesting that the genetic influence is stronger in Adelges spp. Second, the among family variation in genetically controlled resistance was large, i.e. fullsib families differed as much as 10 fold in susceptibility towards Adelges spp. (0.57 to 6.2 galls/branch). Also, the distribution of chemical profiles was continuous, showing both overlap as well as examples of significant differences among fullsib families. Third, despite the predicted effects of host chemistry on galls, principal component analyses using 31 different phenolic substances showed only limited association with galls and a similarity test showed that trees with similar phenolic chemical characteristics, did not host more similar communities of gallers. Nonetheless, the large genetic variation in trait expression and clear differences in how community members respond to host

  14. Host Genetics and Environment Drive Divergent Responses of Two Resource Sharing Gall-Formers on Norway Spruce: A Common Garden Analysis

    PubMed Central

    Axelsson, E. Petter; Iason, Glenn R.; Julkunen-Tiitto, Riitta; Whitham, Thomas G.

    2015-01-01

    A central issue in the field of community genetics is the expectation that trait variation among genotypes play a defining role in structuring associated species and in forming community phenotypes. Quantifying the existence of such community phenotypes in two common garden environments also has important consequences for our understanding of gene-by-environment interactions at the community level. The existence of community phenotypes has not been evaluated in the crowns of boreal forest trees. In this study we address the influence of tree genetics on needle chemistry and genetic x environment interactions on two gall-inducing adelgid aphids (Adelges spp. and Sacchiphantes spp.) that share the same elongating bud/shoot niche. We examine the hypothesis that the canopies of different genotypes of Norway spruce (Picea abies L.) support different community phenotypes. Three patterns emerged. First, the two gallers show clear differences in their response to host genetics and environment. Whereas genetics significantly affected the abundance of Adelges spp. galls, Sacchiphantes spp. was predominately affected by the environment suggesting that the genetic influence is stronger in Adelges spp. Second, the among family variation in genetically controlled resistance was large, i.e. fullsib families differed as much as 10 fold in susceptibility towards Adelges spp. (0.57 to 6.2 galls/branch). Also, the distribution of chemical profiles was continuous, showing both overlap as well as examples of significant differences among fullsib families. Third, despite the predicted effects of host chemistry on galls, principal component analyses using 31 different phenolic substances showed only limited association with galls and a similarity test showed that trees with similar phenolic chemical characteristics, did not host more similar communities of gallers. Nonetheless, the large genetic variation in trait expression and clear differences in how community members respond to host

  15. Genetic background affects the expansion of macrophage subsets in the lungs of Mycobacterium tuberculosis-infected hosts.

    PubMed

    Bertolini, Thais Barboza; de Souza, Alexandre Ignacio; Gembre, Ana Flávia; Piñeros, Annie Rocio; Prado, Rafael de Queiroz; Silva, João Santana; Ramalho, Leandra Naira Zambelli; Bonato, Vânia Luiza Deperon

    2016-05-01

    M1 macrophages are more effective in the induction of the inflammatory response and clearance of Mycobacterium tuberculosis than M2 macrophages. Infected C57BL/6 mice generate a stronger cellular immune response compared with BALB/c mice. We hypothesized that infected C57BL/6 mice would exhibit a higher frequency and function of M1 macrophages than infected BALB/c mice. Our findings show a higher ratio of macrophages to M2 macrophages in the lungs of chronically infected C57BL/6 mice compared with BALB/c mice. However, there was no difference in the functional ability of M1 and M2 macrophages for the two strains in vitro. In vivo, a deleterious role for M2 macrophages was confirmed by M2 cell transfer, which rendered the infected C57BL/6, but not the BALB/c mice, more susceptible and resulted in mild lung inflammation compared with C57BL/6 mice that did not undergo cell transfer. M1 cell transfer induced a higher inflammatory response, although not protective, in infected BALB/c mice compared with their counterparts that did not undergo cell transfer. These findings demonstrate that an inflammation mediated by M1 macrophages may not induce bacterial tolerance because protection depends on the host genetic background, which drives the magnitude of the inflammatory response against M. tuberculosis in the pulmonary microenvironment. The contribution of our findings is that although M1 macrophage is an effector leucocyte with microbicidal machinery, its dominant role depends on the balance of M1 and M2 subsets, which is driven by the host genetic background.

  16. Multi-input CRISPR/Cas genetic circuits that interface host regulatory networks.

    PubMed

    Nielsen, Alec A K; Voigt, Christopher A

    2014-11-24

    Genetic circuits require many regulatory parts in order to implement signal processing or execute algorithms in cells. A potentially scalable approach is to use dCas9, which employs small guide RNAs (sgRNAs) to repress genetic loci via the programmability of RNA:DNA base pairing. To this end, we use dCas9 and designed sgRNAs to build transcriptional logic gates and connect them to perform computation in living cells. We constructed a set of NOT gates by designing five synthetic Escherichia coli σ70 promoters that are repressed by corresponding sgRNAs, and these interactions do not exhibit crosstalk between each other. These sgRNAs exhibit high on-target repression (56- to 440-fold) and negligible off-target interactions (< 1.3-fold). These gates were connected to build larger circuits, including the Boolean-complete NOR gate and a 3-gate circuit consisting of four layered sgRNAs. The synthetic circuits were connected to the native E. coli regulatory network by designing output sgRNAs to target an E. coli transcription factor (malT). This converts the output of a synthetic circuit to a switch in cellular phenotype (sugar utilization, chemotaxis, phage resistance).

  17. Genetically based polymorphisms in morphology and life history associated with putative host races of the water lily leaf beetle, Galerucella nymphaeae.

    PubMed

    Pappers, Stephanie M; van der Velde, Gerard; Ouborg, N Joop; van Groenendael, Jan M

    2002-08-01

    A host race is a population that is partially reproductively isolated from other conspecific populations as a direct consequence of adaptation to a specific host. The initial step in host race formation is the establishment of genetically based polymorphisms in, for example, morphology, preference, or performance. In this study we investigated whether polymorphisms observed in Galerucella nymphaeae have a genetic component. Galerucella nymphaeae, the water lily leaf beetle, is a herbivore which feeds and oviposits on the plant hosts Nuphar lutea and Nymphaea alba (both Nymphaeaceae) and Rumex hydrolapathum and Polygonum amphibium (both Polygonaceae). A full reciprocal crossing scheme (16 crosses, each replicated 10 times) and subsequent transplantation of 1,001 egg clutches revealed a genetic basis for differences in body length and mandibular width. The heritability value of these traits, based on midparent-offspring regression, ranged between 0.53 and 0.83 for the different diets. Offspring from Nymphaeaceae parents were on average 12% larger and had on average 18% larger mandibles than offspring from Polygonaceae parents. Furthermore, highly significant correlations were found between feeding preference of the offspring and the feeding preference of their parents. Finally, two fitness components were measured: development time and survival. Development time was influenced by diet, survival both by cross type and diet, the latter of which suggest adaptation of the beetles. This suggestion is strengthened by a highly significant cross x diet interaction effect for development time as well as for survival, which is generally believed to indicate local adaptation. Although no absolute genetic incompatibility among putative host races was observed, survival of the between-host family offspring, on each diet separately, was lower than the survival of the within-host family offspring on that particular host. Survival of offspring of two Nymphaeaceae parents was about

  18. A Population Genomics Approach to Assessing the Genetic Basis of Within-Host Microevolution Underlying Recurrent Cryptococcal Meningitis Infection.

    PubMed

    Rhodes, Johanna; Beale, Mathew A; Vanhove, Mathieu; Jarvis, Joseph N; Kannambath, Shichina; Simpson, John A; Ryan, Anthea; Meintjes, Graeme; Harrison, Thomas S; Fisher, Matthew C; Bicanic, Tihana

    2017-04-03

    Recurrence of meningitis due to Cryptococcus neoformans after treatment causes substantial mortality in HIV/AIDS patients across sub-Saharan Africa. In order to determine whether recurrence occurred due to relapse of the original infecting isolate or reinfection with a different isolate weeks or months after initial treatment, we used whole-genome sequencing (WGS) to assess the genetic basis of infection in 17 HIV-infected individuals with recurrent cryptococcal meningitis (CM). Comparisons revealed a clonal relationship for 15 pairs of isolates recovered before and after recurrence showing relapse of the original infection. The two remaining pairs showed high levels of genetic heterogeneity; in one pair we found this to be a result of infection by mixed genotypes, while the second was a result of nonsense mutations in the gene encoding the DNA mismatch repair proteins MSH2, MSH5, and RAD5 These nonsense mutations led to a hypermutator state, leading to dramatically elevated rates of synonymous and nonsynonymous substitutions. Hypermutator phenotypes owing to nonsense mutations in these genes have not previously been reported in C. neoformans, and represent a novel pathway for rapid within-host adaptation and evolution of resistance to first-line antifungal drugs.

  19. Effectiveness of vaccination with recombinant HpaA from Helicobacter pylori is influenced by host genetic background.

    PubMed

    Sutton, Philip; Doidge, Christopher; Pinczower, Gideon; Wilson, John; Harbour, Stacey; Swierczak, Agnieszka; Lee, Adrian

    2007-07-01

    Several studies have explored the production and immunogenicity of HpaA as a potential protective antigen against Helicobacter pylori but little is known regarding its protective capabilities. We therefore evaluated the protective efficacy of recombinant HpaA (rHpaA) as a candidate vaccine antigen against H. pylori. To explore the impact of genetic diversity, inbred and outbred mice were prophylactically and therapeutically immunized with rHpaA adjuvanted with cholera toxin (CT). Prophylactic immunization induced a reduction in bacterial colonization in BALB/c and QS mice, but was ineffective in C57BL/6 mice, despite induction of antigen-specific antibodies. By contrast, therapeutic immunization was effective in all three strains of mice. Prophylactic immunization with CT-adjuvanted rHpaA was more effective when delivered via the nasal route than following intragastric delivery in BALB/c mice. However, HpaA-mediated protection was inferior to that induced by bacterial lysate. Hence, protective efficacy is inducible with vaccines containing HpaA, most relevantly shown in an outbred population of mice. The effectiveness of protection induced by HpaA antigen was influenced by host genetics and was less effective than lysate. HpaA therefore has potential for the development of effective immunization against H. pylori but this would probably entail the antigen to be one component of a multiantigenic vaccine.

  20. A Population Genomics Approach to Assessing the Genetic Basis of Within-Host Microevolution Underlying Recurrent Cryptococcal Meningitis Infection

    PubMed Central

    Rhodes, Johanna; Beale, Mathew A.; Vanhove, Mathieu; Jarvis, Joseph N.; Kannambath, Shichina; Simpson, John A.; Ryan, Anthea; Meintjes, Graeme; Harrison, Thomas S.; Fisher, Matthew C.; Bicanic, Tihana

    2017-01-01

    Recurrence of meningitis due to Cryptococcus neoformans after treatment causes substantial mortality in HIV/AIDS patients across sub-Saharan Africa. In order to determine whether recurrence occurred due to relapse of the original infecting isolate or reinfection with a different isolate weeks or months after initial treatment, we used whole-genome sequencing (WGS) to assess the genetic basis of infection in 17 HIV-infected individuals with recurrent cryptococcal meningitis (CM). Comparisons revealed a clonal relationship for 15 pairs of isolates recovered before and after recurrence showing relapse of the original infection. The two remaining pairs showed high levels of genetic heterogeneity; in one pair we found this to be a result of infection by mixed genotypes, while the second was a result of nonsense mutations in the gene encoding the DNA mismatch repair proteins MSH2, MSH5, and RAD5. These nonsense mutations led to a hypermutator state, leading to dramatically elevated rates of synonymous and nonsynonymous substitutions. Hypermutator phenotypes owing to nonsense mutations in these genes have not previously been reported in C. neoformans, and represent a novel pathway for rapid within-host adaptation and evolution of resistance to first-line antifungal drugs. PMID:28188180

  1. Reduced host-specificity in a parasite infecting non-littoral Lake Tanganyika cichlids evidenced by intraspecific morphological and genetic diversity

    PubMed Central

    Kmentová, Nikol; Gelnar, Milan; Mendlová, Monika; Van Steenberge, Maarten; Koblmüller, Stephan; Vanhove, Maarten P. M.

    2016-01-01

    Lake Tanganyika is well-known for its high species-richness and rapid radiation processes. Its assemblage of cichlid fishes recently gained momentum as a framework to study parasite ecology and evolution. It offers a rare chance to investigate the influence of a deepwater lifestyle in a freshwater fish-parasite system. Our study represents the first investigation of parasite intraspecific genetic structure related to host specificity in the lake. It focused on the monogenean flatworm Cichlidogyrus casuarinus infecting deepwater cichlids belonging to Bathybates and Hemibates. Morphological examination of C. casuarinus had previously suggested a broad host range, while the lake’s other Cichlidogyrus species are usually host specific. However, ongoing speciation or cryptic diversity could not be excluded. To distinguish between these hypotheses, we analysed intraspecific diversity of C. casuarinus. Monogeneans from nearly all representatives of the host genera were examined using morphometrics, geomorphometrics and genetics. We confirmed the low host-specificity of C. casuarinus based on morphology and nuclear DNA. Yet, intraspecific variation of sclerotized structures was observed. Nevertheless, the highly variable mitochondrial DNA indicated recent population expansion, but no ongoing parasite speciation, confirming, for the first time in freshwater, reduced parasite host specificity in the deepwater realm, probably an adaptation to low host availability. PMID:28004766

  2. IL-17 Genetic and Immunophenotypic Evaluation in Chronic Graft-versus-Host Disease

    PubMed Central

    Resende, Renata Gonçalves; Correia-Silva, Jeane de Fátima; Silva, Tarcília Aparecida; Salomão, Ulisses Eliezer; Marques-Silva, Luciano; Vieira, Érica Leandro Marciano; Dutra, Walderez Ornelas; Gomez, Ricardo Santiago

    2014-01-01

    Although interleukin-17 (IL-17) is a recently discovered cytokine associated with several autoimmune diseases, its role in the pathogenesis of chronic graft-versus-host disease (cGVHD) was not established yet. The objective of this study was to investigate the association of IL17A and IL17F genes polymorphisms and IL-17A and IL-17F levels with cGVHD. IL-17A expression was also investigated in CD4+ T cells of patients with systemic cGVHD. For Part I of the study, fifty-eight allo-HSCT recipients and donors were prospectively studied. Blood samples were obtained to determine IL17A and IL17F genes polymorphisms. Cytokines levels in blood and saliva were assessed by ELISA at days +35 and +100 after HSCT. In Part II, for the immunophenotypic evaluation, eight patients with systemic cGVHD were selected and the expression of IL-17A was evaluated. We found association between recipient AA genotype with systemic cGVHD. No association was observed between IL-17A levels and cGVHD. Lower IL-17A levels in the blood were associated with AA genotype. In flow cytometry analysis, decreased expression of IL-17A was observed in patients with cGVHD after stimulation. In conclusion, IL-17A may have an important role in the development of systemic cGVHD. PMID:25136146

  3. Host-microbe interactions have shaped the genetic architecture of inflammatory bowel disease

    PubMed Central

    Jostins, Luke; Ripke, Stephan; Weersma, Rinse K; Duerr, Richard H; McGovern, Dermot P; Hui, Ken Y; Lee, James C; Schumm, L Philip; Sharma, Yashoda; Anderson, Carl A; Essers, Jonah; Mitrovic, Mitja; Ning, Kaida; Cleynen, Isabelle; Theatre, Emilie; Spain, Sarah L; Raychaudhuri, Soumya; Goyette, Philippe; Wei, Zhi; Abraham, Clara; Achkar, Jean-Paul; Ahmad, Tariq; Amininejad, Leila; Ananthakrishnan, Ashwin N; Andersen, Vibeke; Andrews, Jane M; Baidoo, Leonard; Balschun, Tobias; Bampton, Peter A; Bitton, Alain; Boucher, Gabrielle; Brand, Stephan; Büning, Carsten; Cohain, Ariella; Cichon, Sven; D’Amato, Mauro; De Jong, Dirk; Devaney, Kathy L; Dubinsky, Marla; Edwards, Cathryn; Ellinghaus, David; Ferguson, Lynnette R; Franchimont, Denis; Fransen, Karin; Gearry, Richard; Georges, Michel; Gieger, Christian; Glas, Jürgen; Haritunians, Talin; Hart, Ailsa; Hawkey, Chris; Hedl, Matija; Hu, Xinli; Karlsen, Tom H; Kupcinskas, Limas; Kugathasan, Subra; Latiano, Anna; Laukens, Debby; Lawrance, Ian C; Lees, Charlie W; Louis, Edouard; Mahy, Gillian; Mansfield, John; Morgan, Angharad R; Mowat, Craig; Newman, William; Palmieri, Orazio; Ponsioen, Cyriel Y; Potocnik, Uros; Prescott, Natalie J; Regueiro, Miguel; Rotter, Jerome I; Russell, Richard K; Sanderson, Jeremy D; Sans, Miquel; Satsangi, Jack; Schreiber, Stefan; Simms, Lisa A; Sventoraityte, Jurgita; Targan, Stephan R; Taylor, Kent D; Tremelling, Mark; Verspaget, Hein W; De Vos, Martine; Wijmenga, Cisca; Wilson, David C; Winkelmann, Juliane; Xavier, Ramnik J; Zeissig, Sebastian; Zhang, Bin; Zhang, Clarence K; Zhao, Hongyu; Silverberg, Mark S; Annese, Vito; Hakonarson, Hakon; Brant, Steven R; Radford-Smith, Graham; Mathew, Christopher G; Rioux, John D; Schadt, Eric E; Daly, Mark J; Franke, Andre; Parkes, Miles; Vermeire, Severine; Barrett, Jeffrey C; Cho, Judy H

    2012-01-01

    Crohn’s disease (CD) and ulcerative colitis (UC), the two common forms of inflammatory bowel disease (IBD), affect over 2.5 million people of European ancestry with rising prevalence in other populations1. Genome-wide association studies (GWAS) and subsequent meta-analyses of CD and UC2,3 as separate phenotypes implicated previously unsuspected mechanisms, such as autophagy4, in pathogenesis and showed that some IBD loci are shared with other inflammatory diseases5. Here we expand knowledge of relevant pathways by undertaking a meta-analysis of CD and UC genome-wide association scans, with validation of significant findings in more than 75,000 cases and controls. We identify 71 new associations, for a total of 163 IBD loci that meet genome-wide significance thresholds. Most loci contribute to both phenotypes, and both directional and balancing selection effects are evident. Many IBD loci are also implicated in other immune-mediated disorders, most notably with ankylosing spondylitis and psoriasis. We also observe striking overlap between susceptibility loci for IBD and mycobacterial infection. Gene co-expression network analysis emphasizes this relationship, with pathways shared between host responses to mycobacteria and those predisposing to IBD. PMID:23128233

  4. Host-microbe interactions have shaped the genetic architecture of inflammatory bowel disease.

    PubMed

    Jostins, Luke; Ripke, Stephan; Weersma, Rinse K; Duerr, Richard H; McGovern, Dermot P; Hui, Ken Y; Lee, James C; Schumm, L Philip; Sharma, Yashoda; Anderson, Carl A; Essers, Jonah; Mitrovic, Mitja; Ning, Kaida; Cleynen, Isabelle; Theatre, Emilie; Spain, Sarah L; Raychaudhuri, Soumya; Goyette, Philippe; Wei, Zhi; Abraham, Clara; Achkar, Jean-Paul; Ahmad, Tariq; Amininejad, Leila; Ananthakrishnan, Ashwin N; Andersen, Vibeke; Andrews, Jane M; Baidoo, Leonard; Balschun, Tobias; Bampton, Peter A; Bitton, Alain; Boucher, Gabrielle; Brand, Stephan; Büning, Carsten; Cohain, Ariella; Cichon, Sven; D'Amato, Mauro; De Jong, Dirk; Devaney, Kathy L; Dubinsky, Marla; Edwards, Cathryn; Ellinghaus, David; Ferguson, Lynnette R; Franchimont, Denis; Fransen, Karin; Gearry, Richard; Georges, Michel; Gieger, Christian; Glas, Jürgen; Haritunians, Talin; Hart, Ailsa; Hawkey, Chris; Hedl, Matija; Hu, Xinli; Karlsen, Tom H; Kupcinskas, Limas; Kugathasan, Subra; Latiano, Anna; Laukens, Debby; Lawrance, Ian C; Lees, Charlie W; Louis, Edouard; Mahy, Gillian; Mansfield, John; Morgan, Angharad R; Mowat, Craig; Newman, William; Palmieri, Orazio; Ponsioen, Cyriel Y; Potocnik, Uros; Prescott, Natalie J; Regueiro, Miguel; Rotter, Jerome I; Russell, Richard K; Sanderson, Jeremy D; Sans, Miquel; Satsangi, Jack; Schreiber, Stefan; Simms, Lisa A; Sventoraityte, Jurgita; Targan, Stephan R; Taylor, Kent D; Tremelling, Mark; Verspaget, Hein W; De Vos, Martine; Wijmenga, Cisca; Wilson, David C; Winkelmann, Juliane; Xavier, Ramnik J; Zeissig, Sebastian; Zhang, Bin; Zhang, Clarence K; Zhao, Hongyu; Silverberg, Mark S; Annese, Vito; Hakonarson, Hakon; Brant, Steven R; Radford-Smith, Graham; Mathew, Christopher G; Rioux, John D; Schadt, Eric E; Daly, Mark J; Franke, Andre; Parkes, Miles; Vermeire, Severine; Barrett, Jeffrey C; Cho, Judy H

    2012-11-01

    Crohn's disease and ulcerative colitis, the two common forms of inflammatory bowel disease (IBD), affect over 2.5 million people of European ancestry, with rising prevalence in other populations. Genome-wide association studies and subsequent meta-analyses of these two diseases as separate phenotypes have implicated previously unsuspected mechanisms, such as autophagy, in their pathogenesis and showed that some IBD loci are shared with other inflammatory diseases. Here we expand on the knowledge of relevant pathways by undertaking a meta-analysis of Crohn's disease and ulcerative colitis genome-wide association scans, followed by extensive validation of significant findings, with a combined total of more than 75,000 cases and controls. We identify 71 new associations, for a total of 163 IBD loci, that meet genome-wide significance thresholds. Most loci contribute to both phenotypes, and both directional (consistently favouring one allele over the course of human history) and balancing (favouring the retention of both alleles within populations) selection effects are evident. Many IBD loci are also implicated in other immune-mediated disorders, most notably with ankylosing spondylitis and psoriasis. We also observe considerable overlap between susceptibility loci for IBD and mycobacterial infection. Gene co-expression network analysis emphasizes this relationship, with pathways shared between host responses to mycobacteria and those predisposing to IBD.

  5. Beneficial bacteria stimulate host immune cells to counteract dietary and genetic predisposition to mammary cancer in mice

    PubMed Central

    Lakritz, Jessica R; Poutahidis, Theofilos; Levkovich, Tatiana; Varian, Bernard J; Ibrahim, Yassin M; Chatzigiagkos, Antonis; Mirabal, Sheyla; Alm, Eric J; Erdman, Susan E

    2014-01-01

    Recent studies suggest health benefits including protection from cancer after eating fermented foods such as probiotic yogurt, though the mechanisms are not well understood. Here we tested mechanistic hypotheses using two different animal models: the first model studied development of mammary cancer when eating a Westernized diet, and the second studied animals with a genetic predilection to breast cancer. For the first model, outbred Swiss mice were fed a Westernized chow putting them at increased risk for development of mammary tumors. In this Westernized diet model, mammary carcinogenesis was inhibited by routine exposure to Lactobacillus reuteri ATCC-PTA-6475 in drinking water. The second model was FVB strain erbB2 (HER2) mutant mice, genetically susceptible to mammary tumors mimicking breast cancers in humans, being fed a regular (non-Westernized) chow diet. We found that oral supplement with these purified lactic acid bacteria alone was sufficient to inhibit features of mammary neoplasia in both models. The protective mechanism was determined to be microbially-triggered CD4+CD25+ lymphocytes. When isolated and transplanted into other subjects, these L. reuteri-stimulated lymphocytes were sufficient to convey transplantable anti-cancer protection in the cell recipient animals. These data demonstrate that host immune responses to environmental microbes significantly impact and inhibit cancer progression in distal tissues such as mammary glands, even in genetically susceptible mice. This leads us to conclude that consuming fermentative microbes such as L. reuteri may offer a tractable public health approach to help counteract the accumulated dietary and genetic carcinogenic events integral in the Westernized diet and lifestyle. What's new? Can eating fermented foods like yogurt ward off cancer? Recent studies have suggested it's possible. To find out how, these authors isolated the probiotic bacteria involved in fermentation and fed them to mice that were

  6. Genetic parameters for indicators of host resistance to parasites from weaning to hogget age in Merino sheep.

    PubMed

    Pollott, G E; Karlsson, L J E; Eady, S; Greeff, J C

    2004-10-01

    Fecal egg count (FEC) has been widely used as an indicator of host resistance to gastrointestinal parasites in sheep and has been shown to be a heritable trait. Two other possible indicators of parasites, dag score (DS; accumulated fecal material) and fecal consistency score (FCS), were investigated in this study, along with BW. All four traits were studied to see how heritability and genetic correlations varied with age from weaning (4 mo) to hogget age (approximately 400 d). More than 1,100 lambs, the offspring of 37 rams, were recorded eight times between weaning (3 to 5 mo of age) and hogget age (13 to 18 mo of age) on two farms. Sire models were fitted to the data from each trait at each recording and in a repeatability model involving the whole data set. Overall, the heritabilities were 0.28+/-0.072 (FEC), 0.11+/-0.036 (DS), 0.12+/-0.036 (FCS), and 0.23+/-0.070 (BW). By fitting random regression models to the time-series data, it was possible to see how these heritability values varied as the lambs aged, from weaning to hogget age. The heritability of FEC rose from 0.2 at weaning to 0.65 at 400 d. Dag score had a higher heritability (0.25) in the middle of the age range and a low value at weaning (<0.1) and hogget age (0.16). The heritability of FCS was low, with a value of 0.2 at weaning reducing to 0.05 as the animals aged. Body weight had zero heritability at weaning, which rose to greater than 0.6 at hogget age. Most traits had low genetic correlations between them, the only exception being that between FCS and DS (0.63). Most genetic correlations varied little over the age range with the exception of FEC and BW, which fell from 0 at weaning to -0.63 at hogget age. Whereas FCS and DS may be good indicators of scouring, they are very different from FEC as an indicator of host resistance to gastrointestinal parasites.

  7. The genetic basis of resistance and matching-allele interactions of a host-parasite system: The Daphnia magna-Pasteuria ramosa model.

    PubMed

    Bento, Gilberto; Routtu, Jarkko; Fields, Peter D; Bourgeois, Yann; Du Pasquier, Louis; Ebert, Dieter

    2017-02-21

    Negative frequency-dependent selection (NFDS) is an evolutionary mechanism suggested to govern host-parasite coevolution and the maintenance of genetic diversity at host resistance loci, such as the vertebrate MHC and R-genes in plants. Matching-allele interactions of hosts and parasites that prevent the emergence of host and parasite genotypes that are universally resistant and infective are a genetic mechanism predicted to underpin NFDS. The underlying genetics of matching-allele interactions are unknown even in host-parasite systems with empirical support for coevolution by NFDS, as is the case for the planktonic crustacean Daphnia magna and the bacterial pathogen Pasteuria ramosa. We fine-map one locus associated with D. magna resistance to P. ramosa and genetically characterize two haplotypes of the Pasteuria resistance (PR-) locus using de novo genome and transcriptome sequencing. Sequence comparison of PR-locus haplotypes finds dramatic structural polymorphisms between PR-locus haplotypes including a large portion of each haplotype being composed of non-homologous sequences resulting in haplotypes differing in size by 66 kb. The high divergence of PR-locus haplotypes suggest a history of multiple, diverse and repeated instances of structural mutation events and restricted recombination. Annotation of the haplotypes reveals striking differences in gene content. In particular, a group of glycosyltransferase genes that is present in the susceptible but absent in the resistant haplotype. Moreover, in natural populations, we find that the PR-locus polymorphism is associated with variation in resistance to different P. ramosa genotypes, pointing to the PR-locus polymorphism as being responsible for the matching-allele interactions that have been previously described for this system. Our results conclusively identify a genetic basis for the matching-allele interaction observed in a coevolving host-parasite system and provide a first insight into its molecular basis.

  8. The genetic basis of resistance and matching-allele interactions of a host-parasite system: The Daphnia magna-Pasteuria ramosa model

    PubMed Central

    Fields, Peter D.; Bourgeois, Yann; Du Pasquier, Louis; Ebert, Dieter

    2017-01-01

    Negative frequency-dependent selection (NFDS) is an evolutionary mechanism suggested to govern host-parasite coevolution and the maintenance of genetic diversity at host resistance loci, such as the vertebrate MHC and R-genes in plants. Matching-allele interactions of hosts and parasites that prevent the emergence of host and parasite genotypes that are universally resistant and infective are a genetic mechanism predicted to underpin NFDS. The underlying genetics of matching-allele interactions are unknown even in host-parasite systems with empirical support for coevolution by NFDS, as is the case for the planktonic crustacean Daphnia magna and the bacterial pathogen Pasteuria ramosa. We fine-map one locus associated with D. magna resistance to P. ramosa and genetically characterize two haplotypes of the Pasteuria resistance (PR-) locus using de novo genome and transcriptome sequencing. Sequence comparison of PR-locus haplotypes finds dramatic structural polymorphisms between PR-locus haplotypes including a large portion of each haplotype being composed of non-homologous sequences resulting in haplotypes differing in size by 66 kb. The high divergence of PR-locus haplotypes suggest a history of multiple, diverse and repeated instances of structural mutation events and restricted recombination. Annotation of the haplotypes reveals striking differences in gene content. In particular, a group of glycosyltransferase genes that is present in the susceptible but absent in the resistant haplotype. Moreover, in natural populations, we find that the PR-locus polymorphism is associated with variation in resistance to different P. ramosa genotypes, pointing to the PR-locus polymorphism as being responsible for the matching-allele interactions that have been previously described for this system. Our results conclusively identify a genetic basis for the matching-allele interaction observed in a coevolving host-parasite system and provide a first insight into its molecular basis

  9. Molecular evidence of host-associated genetic divergence in the holly leafminer Phytomyza glabricola (Diptera: Agromyzidae): apparent discordance among marker systems.

    PubMed

    Scheffer, Sonja J; Hawthorne, David J

    2007-07-01

    Host races play a central part in understanding the role of host plant mediated divergence and speciation of phytophagous insects. Of greatest interest are host-associated populations that have recently diverged; however, finding genetic evidence for very recent divergences is difficult because initially only a few loci are expected to evolve diagnostic differences. The holly leafminer Phytomyza glabricola feeds on two hollies, Ilex glabra and I. coriacea, that are broadly sympatric throughout most of their ranges. The leafminer is often present on both host plants and exhibits a dramatic life history difference on the two hosts, suggesting that host races may be present. We collected 1393 bp of mitochondrial cytochrome oxidase I (COI) sequence and amplified fragment length polymorphism (AFLP) data (45 polymorphic bands) from sympatric populations of flies reared from the two hosts. Phylogenetic and frequency analysis of mitochondrial COI sequence data uncovered considerable variation but no structuring by the host plant, and only limited differentiation among geographical locations. In contrast, analysis of AFLP frequency data found a significant effect with host plant, and a much smaller effect with geographical location. Likewise, neighbour-joining analysis of AFLP data resulted in clustering by host plant. The AFLP data indicate that P. glabricola is most likely comprised of two host races. Because there were no fixed differences in mitochondrial or AFLP data, this host-associated divergence is likely to have occurred very recently. P. glabricola therefore provides a new sympatric system for exploring the role of geography and ecological specialization in the speciation of phytophagous insects.

  10. Genetic Diversity and Population Structure of Busseola segeta Bowden (Lepidoptera; Noctuidae): A Case Study of Host Use Diversification in Guineo-Congolian Rainforest Relic Area, Kenya.

    PubMed

    Ong'amo, George O; Ru, Bruno P Le; Campagne, Pascal; Branca, Antoine; Calatayud, Paul-Andre; Capdevielle-Dulac, Claire; Silvain, Jean-Francois

    2012-11-06

    Habitat modification and fragmentation are considered as some of the factors that drive organism distribution and host use diversification. Indigenous African stem borer pests are thought to have diversified their host ranges to include maize [Zea mays L.] and sorghum [Sorghum bicolor (L.) Moench] in response to their increased availability through extensive cultivation. However, management efforts have been geared towards reducing pest populations in the cultivated fields with few attempts to understand possible evolution of "new" pest species. Recovery and growing persistence of Busseola segeta Bowden on maize (Zea mays L.) in Kakamega called for studies on the role of wild host plants on the invasion of crops by wild borer species. A two-year survey was carried out in a small agricultural landscape along the edge of Kakamega forest (Kenya) to assess host range and population genetic structure of B. segeta. The larvae of B. segeta were found on nine different plant species with the majority occurring on maize and sorghum. Of forty cytochrome b haplotypes identified, twenty-three occurred in both wild and cultivated habitats. The moths appear to fly long distances across the habitats with genetic analyses revealing weak differentiation between hosts in different habitats (FST = 0.016; p = 0.015). However, there was strong evidence of variation in genetic composition between growing seasons in the wild habitat (FST = 0.060; p < 0.001) with emergence or disappearance of haplotypes between habitats. Busseola segeta is an example of a phytophagous insect that utilizes plants with a human induced distribution range, maize, but does not show evidence of host race formation or reduction of gene flow among populations using different hosts. However, B. segeta is capable of becoming an important pest in the area and the current low densities may be attributed to the general low infestation levels and presence of a wide range of alternative hosts in the area.

  11. Host-plant specialization in the Drosophila melanogaster species complex: a physiological, behavioral, and genetical analysis.

    PubMed

    R'Kha, S; Capy, P; David, J R

    1991-03-01

    Drosophila sechellia, endemic to the Seychelles, breeds in a single resource, Morinda citrifolia, whereas its close sympatric relative, Drosophila simulans, is a cosmopolitan generalist breeding in a great variety of resources. The effects of morinda on various fitness traits of these two species, their F1 hybrids, and reciprocal backcrosses were analyzed. Morinda fruit is highly toxic to Drosophila species, except D. sechellia. The toxicity is expressed in adults, embryos, and larvae. In embryos, early mortality is a maternally inherited trait, depending only on mother's genotype. The tolerance of D. sechellia to morinda is fully dominant in F1 hybrids. Egg production is stimulated by morinda in D. sechellia but inhibited in D. simulans; in hybrids, the inhibition observed in D. simulans is dominant. Morinda is an oviposition attractant for D. sechellia but a repellent for D. simulans; F1 hybrids and backcross individuals exhibit intermediate, approximately additive, behavior. In the field, adult flies of the two species exhibit opposite behavior in that D. sechellia is attracted to morinda and D. simulans is attracted to banana; hybrids have an intermediate behavior. These differences between the species explain why they do not hybridize in nature although living in sympatry. The various traits have different genetic bases: three or four different genes, or groups of genes, differentiate the ecological niches of the two species.

  12. Host-plant specialization in the Drosophila melanogaster species complex: a physiological, behavioral, and genetical analysis.

    PubMed Central

    R'Kha, S; Capy, P; David, J R

    1991-01-01

    Drosophila sechellia, endemic to the Seychelles, breeds in a single resource, Morinda citrifolia, whereas its close sympatric relative, Drosophila simulans, is a cosmopolitan generalist breeding in a great variety of resources. The effects of morinda on various fitness traits of these two species, their F1 hybrids, and reciprocal backcrosses were analyzed. Morinda fruit is highly toxic to Drosophila species, except D. sechellia. The toxicity is expressed in adults, embryos, and larvae. In embryos, early mortality is a maternally inherited trait, depending only on mother's genotype. The tolerance of D. sechellia to morinda is fully dominant in F1 hybrids. Egg production is stimulated by morinda in D. sechellia but inhibited in D. simulans; in hybrids, the inhibition observed in D. simulans is dominant. Morinda is an oviposition attractant for D. sechellia but a repellent for D. simulans; F1 hybrids and backcross individuals exhibit intermediate, approximately additive, behavior. In the field, adult flies of the two species exhibit opposite behavior in that D. sechellia is attracted to morinda and D. simulans is attracted to banana; hybrids have an intermediate behavior. These differences between the species explain why they do not hybridize in nature although living in sympatry. The various traits have different genetic bases: three or four different genes, or groups of genes, differentiate the ecological niches of the two species. Images PMID:1900368

  13. The interplay of restriction-modification systems with mobile genetic elements and their prokaryotic hosts

    PubMed Central

    Oliveira, Pedro H.; Touchon, Marie; Rocha, Eduardo P.C.

    2014-01-01

    The roles of restriction-modification (R-M) systems in providing immunity against horizontal gene transfer (HGT) and in stabilizing mobile genetic elements (MGEs) have been much debated. However, few studies have precisely addressed the distribution of these systems in light of HGT, its mechanisms and its vectors. We analyzed the distribution of R-M systems in 2261 prokaryote genomes and found their frequency to be strongly dependent on the presence of MGEs, CRISPR-Cas systems, integrons and natural transformation. Yet R-M systems are rare in plasmids, in prophages and nearly absent from other phages. Their abundance depends on genome size for small genomes where it relates with HGT but saturates at two occurrences per genome. Chromosomal R-M systems might evolve under cycles of purifying and relaxed selection, where sequence conservation depends on the biochemical activity and complexity of the system and total gene loss is frequent. Surprisingly, analysis of 43 pan-genomes suggests that solitary R-M genes rarely arise from the degradation of R-M systems. Solitary genes are transferred by large MGEs, whereas complete systems are more frequently transferred autonomously or in small MGEs. Our results suggest means of testing the roles for R-M systems and their associations with MGEs. PMID:25120263

  14. Genetic differentiation among Maruca vitrata F. (Lepidoptera: Crambidae) populations on cultivated cowpea and wild host plants: implications for insect resistance management and biological control strategies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maruca vitrata is a polyphagous insect pest on a wide variety of leguminous plants in the tropics and subtropics. The contribution of host-associated genetic variation on population structure was investigated using analysis mitochondrial cox1 sequence and microsatellite marker data from M. vitrata c...

  15. The genetic structure of hypoderatid mites (Actinotrichida: Astigmata) parasitizing great cormorant (Phalacrocorax carbo) during host post-breeding dispersal in Milicz, SW Poland.

    PubMed

    Szudarek, Natalia; Kanarek, Gerard; Dabert, Jacek

    2017-03-01

    The astigmatid family Hypoderatidae includes over 80 mite species exhibiting peculiar life cycle. Deutonymphs are parasitic instars inhabiting subcutaneous or visceral tissues of birds and rodents, while all other instars are nidicolous forms. In this study we investigated genetic diversity of deutonymphs of two hypoderatid species, Neottialges evansi and Phalacrodectes gaudi, collected from 16 individuals of the great cormorant Phalacrocorax carbo in SW Poland during host post-breeding dispersal. The initial alternative hypotheses were: (1) populations of deutonymphs in both mite species found in tissues of particular bird individuals form genetically distinct populations, (2) mites are panmictic among hosts. The topologies of NJ phylogenetic trees and median-joining haplotype networks reconstructed for COI haplotypes revealed lack of hostdependent genetic structure in populations of N. evansi and P. gaudi. Furthermore, high haplotype diversity (Hd) and low nucleotide diversity (Pi) prove high genetic differentiation of both mite species. We concluded, that unlimited dispersal of mites among cormorant specimens could be explained by host specific breeding behavior: free mating between cormorants originating from different European populations and low contribution of reunited pairs in breeding colonies in subsequent breeding seasons, reuse of the same nest material by different members of the colony, and host behavior called prospecting.

  16. Borna disease virus-induced neuronal degeneration dependent on host genetic background and prevented by soluble factors.

    PubMed

    Wu, Yuan-Ju; Schulz, Herbert; Lin, Chia-Ching; Saar, Kathrin; Patone, Giannino; Fischer, Heike; Hübner, Norbert; Heimrich, Bernd; Schwemmle, Martin

    2013-01-29

    Infection of newborn rats with Borne disease virus (BDV) results in selective degeneration of granule cell neurons of the dentate gyrus (DG). To study cellular countermechanisms that might prevent this pathology, we screened for rat strains resistant to this BDV-induced neuronal degeneration. To this end, we infected hippocampal slice cultures of different rat strains with BDV and analyzed for the preservation of the DG. Whereas infected cultures of five rat strains, including Lewis (LEW) rats, exhibited a disrupted DG cytoarchitecture, slices of three other rat strains, including Sprague-Dawley (SD), were unaffected. However, efficiency of viral replication was comparable in susceptible and resistant cultures. Moreover, these rat strain-dependent differences in vulnerability were replicated in vivo in neonatally infected LEW and SD rats. Intriguingly, conditioned media from uninfected cultures of both LEW and SD rats could prevent BDV-induced DG damage in infected LEW hippocampal cultures, whereas infection with BDV suppressed the availability of these factors from LEW but not in SD hippocampal cultures. To gain further insights into the genetic basis for this rat strain-dependent susceptibility, we analyzed DG granule cell survival in BDV-infected cultures of hippocampal neurons derived from the F1 and F2 offspring of the crossing of SD and LEW rats. Genome-wide association analysis revealed one resistance locus on chromosome (chr) 6q16 in SD rats and, surprisingly, a locus on chr3q21-23 that was associated with susceptibility. Thus, BDV-induced neuronal degeneration is dependent on the host genetic background and is prevented by soluble protective factors in the disease-resistant SD rat strain.

  17. Host genetics and viral load in primary HIV-1 infection: clear evidence for gene by sex interactions.

    PubMed

    Li, Xuelin; Price, Matthew A; He, Dongning; Kamali, Anatoli; Karita, Etienne; Lakhi, Shabir; Sanders, Eduard J; Anzala, Omu; Amornkul, Pauli N; Allen, Susan; Hunter, Eric; Kaslow, Richard A; Gilmour, Jill; Tang, Jianming

    2014-09-01

    Research in the past two decades has generated unequivocal evidence that host genetic variations substantially account for the heterogeneous outcomes following human immunodeficiency virus type 1 (HIV-1) infection. In particular, genes encoding human leukocyte antigens (HLA) have various alleles, haplotypes, or specific motifs that can dictate the set-point (a relatively steady state) of plasma viral load (VL), although rapid viral evolution driven by innate and acquired immune responses can obscure the long-term relationships between HLA genotypes and HIV-1-related outcomes. In our analyses of VL data from 521 recent HIV-1 seroconverters enrolled from eastern and southern Africa, HLA-A*03:01 was strongly and persistently associated with low VL in women (frequency = 11.3 %, P < 0.0001) but not in men (frequency = 7.7 %, P = 0.66). This novel sex by HLA interaction (P = 0.003, q = 0.090) did not extend to other frequent HLA class I alleles (n = 34), although HLA-C*18:01 also showed a weak association with low VL in women only (frequency = 9.3 %, P = 0.042, q > 0.50). In a reduced multivariable model, age, sex, geography (clinical sites), previously identified HLA factors (HLA-B*18, B*45, B*53, and B*57), and the interaction term for female sex and HLA-A*03:01 collectively explained 17.0 % of the overall variance in geometric mean VL over a 3-year follow-up period (P < 0.0001). Multiple sensitivity analyses of longitudinal and cross-sectional VL data yielded consistent results. These findings can serve as a proof of principle that the gap of "missing heritability" in quantitative genetics can be partially bridged by a systematic evaluation of sex-specific associations.

  18. The role of host genetic factors in respiratory tract infectious diseases: systematic review, meta-analyses and field synopsis

    PubMed Central

    Patarčić, Inga; Gelemanović, Andrea; Kirin, Mirna; Kolčić, Ivana; Theodoratou, Evropi; Baillie, Kenneth J.; de Jong, Menno D.; Rudan, Igor; Campbell, Harry; Polašek, Ozren

    2015-01-01

    Host genetic factors have frequently been implicated in respiratory infectious diseases, often with inconsistent results in replication studies. We identified 386 studies from the total of 24,823 studies identified in a systematic search of four bibliographic databases. We performed meta-analyses of studies on tuberculosis, influenza, respiratory syncytial virus, SARS-Coronavirus and pneumonia. One single-nucleotide polymorphism from IL4 gene was significant for pooled respiratory infections (rs2070874; 1.66 [1.29–2.14]). We also detected an association of TLR2 gene with tuberculosis (rs5743708; 3.19 [2.03–5.02]). Subset analyses identified CCL2 as an additional risk factor for tuberculosis (rs1024611; OR = 0.79 [0.72–0.88]). The IL4-TLR2-CCL2 axis could be a highly interesting target for translation towards clinical use. However, this conclusion is based on low credibility of evidence - almost 95% of all identified studies had strong risk of bias or confounding. Future studies must build upon larger-scale collaborations, but also strictly adhere to the highest evidence-based principles in study design, in order to reduce research waste and provide clinically translatable evidence. PMID:26524966

  19. Genetic Diversity of Toxoplasma gondii Strains from Different Hosts and Geographical Regions by Sequence Analysis of GRA20 Gene.

    PubMed

    Ning, Hong-Rui; Huang, Si-Yang; Wang, Jin-Lei; Xu, Qian-Ming; Zhu, Xing-Quan

    2015-06-01

    Toxoplasma gondii is a eukaryotic parasite of the phylum Apicomplexa, which infects all warm-blood animals, including humans. In the present study, we examined sequence variation in dense granule 20 (GRA20) genes among T. gondii isolates collected from different hosts and geographical regions worldwide. The complete GRA20 genes were amplified from 16 T. gondii isolates using PCR, sequence were analyzed, and phylogenetic reconstruction was analyzed by maximum parsimony (MP) and maximum likelihood (ML) methods. The results showed that the complete GRA20 gene sequence was 1,586 bp in length among all the isolates used in this study, and the sequence variations in nucleotides were 0-7.9% among all strains. However, removing the type III strains (CTG, VEG), the sequence variations became very low, only 0-0.7%. These results indicated that the GRA20 sequence in type III was more divergence. Phylogenetic analysis of GRA20 sequences using MP and ML methods can differentiate 2 major clonal lineage types (type I and type III) into their respective clusters, indicating the GRA20 gene may represent a novel genetic marker for intraspecific phylogenetic analyses of T. gondii.

  20. Tricholoma matsutake in a natural Pinus densiflora forest: correspondence between above- and below-ground genets, association with multiple host trees and alteration of existing ectomycorrhizal communities.

    PubMed

    Lian, Chunlan; Narimatsu, Maki; Nara, Kazuhide; Hogetsu, Taizo

    2006-01-01

    Tricholoma matsutake (matsutake) is an ectomycorrhizal (ECM) fungus that produces economically important mushrooms in Japan. Here, we use microsatellite markers to identify genets of matsutake sporocarps and below-ground ECM tips, as well as associated host genotypes of Pinus densiflora. We also studied ECM fungal community structure inside, beneath and outside the matsutake fairy rings, using morphological and internal transcribed spacer (ITS) polymorphism analysis. Based on sporocarp samples, one to four genets were found within each fairy ring, and no genetic differentiation among six sites was detected. Matsutake ECM tips were only found beneath fairy rings and corresponded with the genotypes of the above-ground sporocarps. We detected nine below-ground matsutake genets, all of which colonized multiple pine trees (three to seven trees per genet). The ECM fungal community beneath fairy rings was species-poor and significantly differed from those inside and outside the fairy rings. We conclude that matsutake genets occasionally establish from basidiospores and expand on the root systems of multiple host trees. Although matsutake mycelia suppress other ECM fungi during expansion, most of them may recover after the passage of the fairy rings.

  1. Temporal and anatomical host resistance to chronic Salmonella infection is quantitatively dictated by Nramp1 and influenced by host genetic background.

    PubMed

    Loomis, Wendy P; Johnson, Matthew L; Brasfield, Alicia; Blanc, Marie-Pierre; Yi, Jaehun; Miller, Samuel I; Cookson, Brad T; Hajjar, Adeline M

    2014-01-01

    The lysosomal membrane transporter, Nramp1, plays a key role in innate immunity and resistance to infection with intracellular pathogens such as non-typhoidal Salmonella (NTS). NTS-susceptible C57BL/6 (B6) mice, which express the mutant Nramp1D169 allele, are unable to control acute infection with Salmonella enterica serovar Typhimurium following intraperitoneal or oral inoculation. Introducing functional Nramp1G169 into the B6 host background, either by constructing a congenic strain carrying Nramp1G169 from resistant A/J mice (Nramp-Cg) or overexpressing Nramp1G169 from a transgene (Nramp-Tg), conferred equivalent protection against acute Salmonella infection. In contrast, the contributions of Nramp1 for controlling chronic infection are more complex, involving temporal and anatomical differences in Nramp1-dependent host responses. Nramp-Cg, Nramp-Tg and NTS-resistant 129×1/SvJ mice survived oral Salmonella infection equally well for the first 2-3 weeks, providing evidence that Nramp1 contributes to the initial control of NTS bacteremia preceding establishment of chronic Salmonella infection. By day 30, increased host Nramp1 expression (Tg>Cg) provided greater protection as indicated by decreased splenic bacterial colonization (Tghost resistance is conferred by Nramp1 expression in NTS-susceptible mice, 2) restriction of systemic bacterial growth in the spleens of NTS-susceptible mice is enhanced by Nramp1 expression and dose-dependent, and 3) host genes other than Nramp1 also contribute to the ability of NTS-resistant 129×1/SvJ mice to control bacterial replication during chronic infection.

  2. Genetic Evidence of Contemporary Dispersal of the Intermediate Snail Host of Schistosoma japonicum: Movement of an NTD Host Is Facilitated by Land Use and Landscape Connectivity

    PubMed Central

    Chang, Howard; Li, Qunna; Hoover, Christopher M.; Wilke, Thomas; Clewing, Catharina; Carlton, Elizabeth J.; Liang, Song; Lu, Ding; Zhong, Bo; Remais, Justin V.

    2016-01-01

    Background While the dispersal of hosts and vectors—through active or passive movement—is known to facilitate the spread and re-emergence of certain infectious diseases, little is known about the movement ecology of Oncomelania spp., intermediate snail host of the parasite Schistosoma japonicum, and its consequences for the spread of schistosomiasis in East and Southeast Asia. In China, despite intense control programs aimed at preventing schistosomiasis transmission, there is evidence in recent years of re-emergence and persistence of infection in some areas, as well as an increase in the spatial extent of the snail host. A quantitative understanding of the dispersal characteristics of the intermediate host can provide new insights into the spatial dynamics of transmission, and can assist public health officials in limiting the geographic spread of infection. Methodology/Principal findings Oncomelania hupensis robertsoni snails (n = 833) were sampled from 29 sites in Sichuan, China, genotyped, and analyzed using Bayesian assignment to estimate the rate of recent snail migration across sites. Landscape connectivity between each site pair was estimated using the geographic distance distributions derived from nine environmental models: Euclidean, topography, incline, wetness, land use, watershed, stream use, streams and channels, and stream velocity. Among sites, 14.4% to 32.8% of sampled snails were identified as recent migrants, with 20 sites comprising >20% migrants. Migration rates were generally low between sites, but at 8 sites, over 10% of the overall host population originated from one proximal site. Greater landscape connectivity was significantly associated with increased odds of migration, with the minimum path distance (as opposed to median or first quartile) emerging as the strongest predictor across all environmental models. Models accounting for land use explained the largest proportion of the variance in migration rates between sites. A greater

  3. Expression of parasite genetic variation changes over the course of infection: implications of within-host dynamics for the evolution of virulence

    PubMed Central

    Clerc, Melanie; Ebert, Dieter; Hall, Matthew D.

    2015-01-01

    How infectious disease agents interact with their host changes during the course of infection and can alter the expression of disease-related traits. Yet by measuring parasite life-history traits at one or few moments during infection, studies have overlooked the impact of variable parasite growth trajectories on disease evolution. Here we show that infection-age-specific estimates of host and parasite fitness components can reveal new insight into the evolution of parasites. We do so by characterizing the within-host dynamics over an entire infection period for five genotypes of the castrating bacterial parasite Pasteuria ramosa infecting the crustacean Daphnia magna. Our results reveal that genetic variation for parasite-induced gigantism, host castration and parasite spore loads increases with the age of infection. Driving these patterns appears to be variation in how well the parasite maintains control of host reproduction late in the infection process. We discuss the evolutionary consequences of this finding with regard to natural selection acting on different ages of infection and the mechanism underlying the maintenance of castration efficiency. Our results highlight how elucidating within-host dynamics can shed light on the selective forces that shape infection strategies and the evolution of virulence. PMID:25761710

  4. Genetic Population Structure of Dastarcus helophoroides (Coleoptera: Bothrideridae) From Different Long-Horned Beetle Hosts Based on Complete Sequences of Mitochondrial COI.

    PubMed

    Zhang, Zhengqing; Chang, Yong; Li, Menglou

    2017-03-03

    Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) is an important natural enemy of long-horned beetles in China, Japan, and Korea. In this study, the genetic sequence of cytochrome oxidase subunit Ι was used to investigate the genetics and relationships within and among D. helophoroides populations collected from five different geographic locations. We used principal component analysis, heatmap, and Venn diagram results to determine the relationship between haplotypes and populations. In total, 26 haplotypes with 51 nucleotide polymorphic sites were defined, and low genetic diversity was found among the different populations. Significant genetic variations were observed mainly within populations, and no correlation was found between genetic distribution and geographical distance. Low pairwise fixation index values (-0.01424 to 0.04896) and high gene flows show that there was high gene exchange between populations. The codistributed haplotype DH01 was suggested to be the most ancestral haplotype, and other haplotypes were thought to have evolved from it through several mutations. In four of the populations, both common haplotypes (DH01, DH03, and DH22) and unique haplotypes were found. Low genetic diversity among different populations is related to a relatively high flight capacity, host movement, and human-aided dispersal of D. helophoroides. The high gene exchange and typically weak population genetic structure among five populations, especially among populations of Anoplophora glabripennis (Motschulsky), Monochamus alternatus (Hope), and Massicus raddei (Blessig), may suggest that these populations cross naturally in the field.

  5. Genetic covariation of the marine fungal symbiont Haloguignardia irritans (Ascomycota, Pezizomycotina) with its algal hosts Cystoseira and Halidrys (Phaeophyceae, Fucales) along the west coast of North America.

    PubMed

    Harvey, J B J; Goff, Lynda J

    2010-01-01

    The fungal endophyte Haloguignardia irritans induces gall formation on the brown algal genera Cystoseira and Halidrys occurring from Oregon to Baja California, Mexico. Here we examine genetic covariation and compare rDNA phylogenies to investigate the coevolutionary histories of H. irritans and its algal hosts. Despite recognition of H. irritans as a single morphological species, internal transcribed spacer rDNA sequences representative of its geographic range are characterized by sequence variation at the intraspecific to intrageneric levels. An assessment of parallel cladogenesis between endophyte and host phylogenies provides evidence for a combination of independent fungal divergence and host jumping, similar to that observed in terrestrial lichens. Our results suggest that reduced gene flow due to geographic isolation is a major contributing factor to more concerted covariation observed at one island site, rather than to differences among algal host species alone. Because geography and its effects on gene flow can create heterogeneous mosaics of coevolution for symbioses in terrestrial environments, our results support the notion that conservation efforts toward the maintenance of genetic diversity in marine environments should likewise consider geographic complexity and its effects on coevolving marine species.

  6. Deep sequencing reveals persistence of intra- and inter-host genetic diversity in natural and greenhouse populations of zucchini yellow mosaic virus.

    PubMed

    Simmons, H E; Dunham, J P; Stack, J C; Dickins, B J A; Pagán, I; Holmes, E C; Stephenson, A G

    2012-08-01

    The genetic diversity present in populations of RNA viruses is likely to be strongly modulated by aspects of their life history, including mode of transmission. However, how transmission mode shapes patterns of intra- and inter-host genetic diversity, particularly when acting in combination with de novo mutation, population bottlenecks and the selection of advantageous mutations, is poorly understood. To address these issues, this study performed ultradeep sequencing of zucchini yellow mosaic virus in a wild gourd, Cucurbita pepo ssp. texana, under two infection conditions: aphid vectored and mechanically inoculated, achieving a mean coverage of approximately 10 ,000×. It was shown that mutations persisted during inter-host transmission events in both the aphid vectored and mechanically inoculated populations, suggesting that the vector-imposed transmission bottleneck is not as extreme as previously supposed. Similarly, mutations were found to persist within individual hosts, arguing against strong systemic bottlenecks. Strikingly, mutations were seen to go to fixation in the aphid-vectored plants, suggestive of a major fitness advantage, but remained at low frequency in the mechanically inoculated plants. Overall, this study highlights the utility of ultradeep sequencing in providing high-resolution data capable of revealing the nature of virus evolution, particularly as the full spectrum of genetic diversity within a population may not be uncovered without sequence coverage of at least 2500-fold.

  7. Host Genetic Variations and Sex Differences Potentiate Predisposition, Severity, and Outcomes of Group A Streptococcus-Mediated Necrotizing Soft Tissue Infections

    PubMed Central

    Mukundan, Santhosh; Alagarsamy, Jeyashree; Laturnus, Donna

    2015-01-01

    Host genetic variations play an important role in several pathogenic diseases, and we previously provided strong evidence that these genetic variations contribute significantly to differences in susceptibility and clinical outcomes of invasive group A Streptococcus (GAS) patients, including sepsis and necrotizing soft tissue infections (NSTIs). The goal of the present study was to investigate how genetic variations and sex differences among four commonly used mouse strains contribute to variation in severity, manifestations, and outcomes of NSTIs. DBA/2J mice were more susceptible to NSTIs than C57BL/6J, BALB/c, and CD-1 mice, as exhibited by significantly greater bacteremia, excessive dissemination to the spleen, and significantly higher mortality. Differences in the sex of the mice also contributed to differences in disease severity and outcomes: DBA/2J female mice were relatively resistant compared to their male counterparts. However, DBA/2J mice exhibited minimal weight loss and developed smaller lesions than did the aforementioned strains. Moreover, at 48 h after infection, compared with C57BL/6J mice, DBA/2J mice had increased bacteremia, excessive dissemination to the spleen, and excessive concentrations of inflammatory cytokines and chemokines. These results indicate that variations in the host genetic context as well as sex play a dominant role in determining the severity of and susceptibility to GAS NSTIs. PMID:26573737

  8. Genetic variation of jointed goatgrass (Aegilops cylindrica Host.) from Iran using RAPD-PCR and SDS-PAGE of seed proteins.

    PubMed

    Farkhari, M; Naghavi, M R; Pyghambari, S A; Sabokdast

    2007-09-01

    Genetic variation of 28 populations of jointed goatgrass (Aegilops cylindrica Host.), collected from different parts of Iran, were evaluated using both RAPD-PCR and SDS-PAGE of seed proteins. The diversity within and between populations for the three-band High Molecular Weight (HMW) subunits of glutenin pattern were extremely low. Out of 15 screened primers of RAPD, 14 primers generated 133 reproducible fragments which among them 92 fragments were polymorphic (69%). Genetic similarity calculated from the RAPD data ranged from 0.64 to 0.98. A dendrogram was prepared on the basis of a similarity matrix using the UPGMA algorithm and separated the 28 populations into two groups. Confusion can happen between populations with the same origin as well as between populations of very diverse geographical origins. Our results show that compare to seed storage protein, RAPD is suitable for genetic diversity assessment in Ae. cylindrica populations.

  9. Genetic variation and variation in aggressiveness to native and exotic hosts among Brazilian populations of Ceratocystis fimbriata.

    PubMed

    Harrington, Thomas C; Thorpe, Daniel J; Alfenas, Acelino C

    2011-05-01

    Ceratocystis fimbriata is a complex of many species that cause wilt and cankers on woody plants and rot of storage roots or corms of many economically important crops worldwide. In Brazil, C. fimbriata infects different cultivated crop plants that are not native to Brazil, including Gmelina arborea, Eucalyptus spp., Mangifera indica (mango), Ficus carica (fig), and Colocasia esculenta (inhame). Phylogenetic analyses and inoculation studies were performed to test the hypothesis that there are host-specialized lineages of C. fimbriata in Brazil. The internal transcribed spacer region ribosomal DNA sequences varied greatly but there was little resolution of lineages based on these sequences. A portion of the MAT1-2 mating type gene showed less variation, and this variation corresponded more closely with host of origin. However, mango isolates were found scattered throughout the tree. Inoculation experiments on the five exotic hosts showed substantial variation in aggressiveness within and among pathogen populations. Native hosts from the same families as the exotic hosts tended to be less susceptible than the cultivated hosts, but there was little correlation between aggressiveness to the cultivated and native hosts of the same family. Cultivation and vegetative propagation of exotic crops may select for strains that are particularly aggressive on those crops.

  10. Host-associated genetic differentiation in a seed parasitic weevil Rhinusa antirrhini (Coleptera: Curculionidae) revealed by mitochondrial and nuclear sequence data.

    PubMed

    Hernández-Vera, Gerardo; Mitrović, Milana; Jović, Jelena; Tosevski, Ivo; Caldara, Roberto; Gassmann, Andre; Emerson, Brent C

    2010-06-01

    Plant feeding insects and the plants they feed upon represent an ecological association that is thought to be a key factor for the diversification of many plant feeding insects, through differential adaptation to different plant selective pressures. While a number of studies have investigated diversification of plant feeding insects above the species level, relatively less attention has been given to patterns of diversification within species, particularly those that also require plants for oviposition and subsequent larval development. In the case of plant feeding insects that also require plant tissues for the completion of their reproductive cycle through larval development, the divergent selective pressure not only acts on adults, but on the full life history of the insect. Here we focus attention on Rhinusa antirrhini (Curculionidae), a species of weevil broadly distributed across Europe that both feeds on, and oviposits and develops within, species of the plant genus Linaria (Plantaginaceae). Using a combination of mtDNA (COII) and nuclear DNA (EF1-alpha) sequencing and copulation experiments we assess evidence for host associated genetic differentiation within R. antirrhini. We find substantial genetic variation within this species that is best explained by ecological specialisation on different host plant taxa. This genetic differentiation is most pronounced in the mtDNA marker, with patterns of genetic variation at the nuclear marker suggesting incomplete lineage sorting and/or gene flow between different host plant forms of R. antirrhini, whose origin is estimated to date to the mid-Pliocene (3.77 Mya; 2.91-4.80 Mya).

  11. Genetic isolation between two sympatric host-plant races of the European corn borer, Ostrinia nubilalis Hübner. I. Sex pheromone, moth emergence timing, and parasitism.

    PubMed

    Thomas, Yan; Bethenod, Marie-Thérèse; Pelozuelo, Laurent; Frérot, Brigitte; Bourguet, Denis

    2003-02-01

    Adaptation to different environments may be a powerful source of genetic differentiation between populations. The biological traits selected in each environment can pleiotropically induce assortative mating between individuals of these genetically differentiated populations. This situation may facilitate sympatric speciation. Successful host shifts in phytophagous insects provide some of the best evidence for the ecological speciation that occurs, or has occurred, in sympatry. The European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), colonized maize after its introduction into Europe by humans about 500 years ago. In northern France, two sympatric host races feed on maize (Zea mays) and mugwort (Artemisia vulgaris), respectively. We investigated the factors involved in the genetic isolation of these two races at a field site near Paris, France. We identified two biological differences that might make a significant contribution to the genetic divergence between sympatric populations feeding on the two host plants. First, assortative mating may be due to differences in the moth emergence pattern between the two races: mugwort-race moths emerged on average 10 days earlier than maize-race moths. In addition, the males emerged earlier than females in both races. Hence, the likelihood of mating between maize-race males and mugwort-race females was higher than that of mating between mugwort-race males and maize-race females. Second, the females feeding on mugwort and maize produced sex pheromones with different E/Z isomeric ratios of delta-11-tetradecenyl acetate. This difference in mate recognition systems reinforces the potential for assortative mating in the two races. During the experiment, overwintering mortality was much lower on maize than on mugwort. This difference was due to a braconid parasitoid wasp, Macrocentrus cingulum, that killed more than 50% of the larvae overwintering on mugwort but did not infest larvae diapausing on maize. Hence, by

  12. Spatially Explicit Modeling of Schistosomiasis Risk in Eastern China Based on a Synthesis of Epidemiological, Environmental and Intermediate Host Genetic Data

    PubMed Central

    Schrader, Matthias; Hauffe, Torsten; Zhang, Zhijie; Davis, George M.; Jopp, Fred; Remais, Justin V.; Wilke, Thomas

    2013-01-01

    Schistosomiasis japonica is a major parasitic disease threatening millions of people in China. Though overall prevalence was greatly reduced during the second half of the past century, continued persistence in some areas and cases of re-emergence in others remain major concerns. As many regions in China are approaching disease elimination, obtaining quantitative data on Schistosoma japonicum parasites is increasingly difficult. This study examines the distribution of schistosomiasis in eastern China, taking advantage of the fact that the single intermediate host serves as a major transmission bottleneck. Epidemiological, population-genetic and high-resolution ecological data are combined to construct a predictive model capable of estimating the probability that schistosomiasis occurs in a target area (“spatially explicit schistosomiasis risk”). Results show that intermediate host genetic parameters are correlated with the distribution of endemic disease areas, and that five explanatory variables—altitude, minimum temperature, annual precipitation, genetic distance, and haplotype diversity—discriminate between endemic and non-endemic zones. Model predictions are correlated with human infection rates observed at the county level. Visualization of the model indicates that the highest risks of disease occur in the Dongting and Poyang lake regions, as expected, as well as in some floodplain areas of the Yangtze River. High risk areas are interconnected, suggesting the complex hydrological interplay of Dongting and Poyang lakes with the Yangtze River may be important for maintaining schistosomiasis in eastern China. Results demonstrate the value of genetic parameters for risk modeling, and particularly for reducing model prediction error. The findings have important consequences both for understanding the determinants of the current distribution of S. japonicum infections, and for designing future schistosomiasis surveillance and control strategies. The results

  13. Genetics

    MedlinePlus

    ... Inheritance; Heterozygous; Inheritance patterns; Heredity and disease; Heritable; Genetic markers ... The chromosomes are made up of strands of genetic information called DNA. Each chromosome contains sections of ...

  14. The Many Dimensions of Diet Breadth: Phytochemical, Genetic, Behavioral, and Physiological Perspectives on the Interaction between a Native Herbivore and an Exotic Host

    PubMed Central

    Harrison, Joshua G.; Gompert, Zachariah; Fordyce, James A.; Buerkle, C. Alex; Grinstead, Rachel; Jahner, Joshua P.; Mikel, Scott; Nice, Christopher C.; Santamaria, Aldrin; Forister, Matthew L.

    2016-01-01

    From the perspective of an herbivorous insect, conspecific host plants are not identical, and intraspecific variation in host nutritional quality or defensive capacity might mediate spatially variable outcomes in plant-insect interactions. Here we explore this possibility in the context of an ongoing host breadth expansion of a native butterfly (the Melissa blue, Lycaeides melissa) onto an exotic host plant (alfalfa, Medicago sativa). We examine variation among seven alfalfa populations that differed in terms of colonization by L. melissa; specifically, we examined variation in phytochemistry, foliar protein, and plant population genetic structure, as well as responses of caterpillars and adult butterflies to foliage from the same populations. Regional patterns of alfalfa colonization by L. melissa were well predicted by phytochemical variation, and colonized patches of alfalfa showed a similar level of inter-individual phytochemical diversity. However, phytochemical variation was a poor predictor of larval performance, despite the fact that survival and weight gain differed dramatically among caterpillars reared on plants from different alfalfa populations. Moreover, we observed a mismatch between alfalfa supporting the best larval performance and alfalfa favored by ovipositing females. Thus, the axes of plant variation that mediate interactions with L. melissa depend upon herbivore life history stage, which raises important issues for our understanding of adaptation to novel resources by an organism with a complex life history. PMID:26836490

  15. Prevalence, Genetic Characterization, and 18S Small Subunit Ribosomal RNA Diversity of Trypanosoma rangeli in Triatomine and Mammal Hosts in Endemic Areas for Chagas Disease in Ecuador

    PubMed Central

    Ocaña-Mayorga, Sofia; Aguirre-Villacis, Fernanda; Pinto, C. Miguel; Vallejo, Gustavo A.

    2015-01-01

    Abstract Trypanosoma rangeli is a nonpathogenic parasite for humans; however, its medical importance relies in its similarity and overlapping distribution with Trypanosoma cruzi, causal agent of Chagas disease in the Americas. The genetic diversity of T. rangeli and its association with host species (triatomines and mammals) has been identified along Central and the South America; however, it has not included data of isolates from Ecuador. This study reports infection with T. rangeli in 18 genera of mammal hosts and five species of triatomines in three environments (domestic, peridomestic, and sylvatic). Higher infection rates were found in the sylvatic environment, in close association with Rhodnius ecuadoriensis. The results of this study extend the range of hosts infected with this parasite and the geographic range of the T. rangeli genotype KP1(−)/lineage C in South America. It was not possible to detect variation on T. rangeli from the central coastal region and southern Ecuador with the analysis of the small subunit ribosomal RNA (SSU-rRNA) gene, even though these areas are ecologically different and a phenotypic subdivision of R. ecuadoriensis has been found. R. ecuadoriensis is considered one of the most important vectors for Chagas disease transmission in Ecuador due to its wide distribution and adaptability to diverse environments. An extensive knowledge of the trypanosomes circulating in this species of triatomine, and associated mammal hosts, is important for delineating transmission dynamics and preventive measures in the endemic areas of Ecuador and Northern Peru. PMID:26645579

  16. Prevalence, Genetic Characterization, and 18S Small Subunit Ribosomal RNA Diversity of Trypanosoma rangeli in Triatomine and Mammal Hosts in Endemic Areas for Chagas Disease in Ecuador.

    PubMed

    Ocaña-Mayorga, Sofia; Aguirre-Villacis, Fernanda; Pinto, C Miguel; Vallejo, Gustavo A; Grijalva, Mario J

    2015-12-01

    Trypanosoma rangeli is a nonpathogenic parasite for humans; however, its medical importance relies in its similarity and overlapping distribution with Trypanosoma cruzi, causal agent of Chagas disease in the Americas. The genetic diversity of T. rangeli and its association with host species (triatomines and mammals) has been identified along Central and the South America; however, it has not included data of isolates from Ecuador. This study reports infection with T. rangeli in 18 genera of mammal hosts and five species of triatomines in three environments (domestic, peridomestic, and sylvatic). Higher infection rates were found in the sylvatic environment, in close association with Rhodnius ecuadoriensis. The results of this study extend the range of hosts infected with this parasite and the geographic range of the T. rangeli genotype KP1(-)/lineage C in South America. It was not possible to detect variation on T. rangeli from the central coastal region and southern Ecuador with the analysis of the small subunit ribosomal RNA (SSU-rRNA) gene, even though these areas are ecologically different and a phenotypic subdivision of R. ecuadoriensis has been found. R. ecuadoriensis is considered one of the most important vectors for Chagas disease transmission in Ecuador due to its wide distribution and adaptability to diverse environments. An extensive knowledge of the trypanosomes circulating in this species of triatomine, and associated mammal hosts, is important for delineating transmission dynamics and preventive measures in the endemic areas of Ecuador and Northern Peru.

  17. Sequential Utilization of Hosts from Different Fly Families by Genetically Distinct, Sympatric Populations within the Entomophthora muscae Species Complex

    PubMed Central

    Gryganskyi, Andrii P.; Humber, Richard A.; Stajich, Jason E.; Mullens, Bradley; Anishchenko, Iryna M.; Vilgalys, Rytas

    2013-01-01

    The fungus Entomophthora muscae (Entomophthoromycota, Entomophthorales, Entomophthoraceae) is a widespread insect pathogen responsible for fatal epizootic events in many dipteran fly hosts. During epizootics in 2011 and 2012 in Durham, North Carolina, we observed a transition of fungal infections from one host, the plant-feeding fly Delia radicum, to a second host, the predatory fly Coenosia tigrina. Infections first appeared on Delia in the middle of March, but by the end of May, Coenosia comprised 100% of infected hosts. Multilocus sequence typing revealed that E. muscae in Durham comprises two distinct subpopulations (clades) with several haplotypes in each. Fungi from either clade are able to infect both fly species, but vary in their infection phenologies and host-specificities. Individuals of the more phylogenetically diverse clade I predominated during the beginning of the spring epizootic, infecting mostly phytophagous Delia flies. Clade II dominated in late April and May and affected mostly predatory Coenosia flies. Analysis of population structure revealed two subpopulations within E. muscae with limited gene exchange. This study provides the first evidence of recombination and population structure within the E. muscae species complex, and illustrates the complexity of insect-fungus relationships that should be considered for development of biological control methods. PMID:23951101

  18. Genetic gradient of a host-parasite pair along a river persisted ten years against physical mobility: Baltic Salmo salar vs. Gyrodactylus salaris.

    PubMed

    Lumme, Jaakko; Anttila, Pasi; Rintamäki, Päivi; Koski, Perttu; Romakkaniemi, Atso

    2016-11-01

    The Atlantic salmon, Salmo salar L., in the Tornio River in the Northern Baltic Sea basin accommodates a monogenean ectoparasite, Gyrodactylus salaris. The aim of the study was to understand the population structure of apparently co-adapted host-parasite system: no parasite-associated mortality has been reported. The parasite burden among salmon juveniles (parr) was monitored along 460km of the river in 2000-2009. Among the parr, 33.0% were infected (nfish=1913). The genetic structure of the parasite population was studied by sequencing an anonymous nuclear DNA marker (ADNAM1, three main genotypes) and mitochondrial CO1 (three clades, six haplotypes). During the ten years, the parasite population was strongly and stably genetically differentiated among up- and downstream nurseries (nADNAM1=411, FST=0.579; nCO1=443, FST=0.534). Infection prevalence among the smolts migrating to sea was higher than in the sedentary parr populations (82.2%, nfish=129). The spatial differentiation observed among the sedentary juveniles was reflected temporally in the smolt run: parasite genotypes dominating the upper part of the river arrived later than downstream dwellers (medians June 4 and June 2) to the trap 7km from the river mouth. The nuclear and mitochondrial markers were in stable disequilibrium which was not relaxed in the contact zone or among the smolts where the parasite clones often met on individual fish. Only five parasite specimens on smolts (nworms=217) were putative recent sexual recombinants. The contribution of extant salmon hatcheries into the infection was negligible. The host salmon population in Tornio River is known to show significant spatial differentiation (FST=0.022). The stable spatial genetic structure of the parasite against the high physical mobility suggested a possibility of local co-adaptation of the host-parasite subpopulations.

  19. The search for host genetic factors of HIV/AIDS pathogenesis in the post-genome era: progress to date and new avenues for discovery.

    PubMed

    Aouizerat, Bradley E; Pearce, C Leigh; Miaskowski, Christine

    2011-03-01

    Though pursuit of host genetic factors that influence the pathogenesis of HIV began over two decades ago, progress has been slow. Initial genome-level searches for variations associated with HIV-related traits have yielded interesting candidates, but less in the way of novel pathways to be exploited for therapeutic targets. More recent genome-wide association studies (GWAS) that include different phenotypes, novel designs, and that have examined different population characteristics suggest novel targets and affirm the utility of additional searches. Recent findings from these GWAS are reviewed, new directions for research are identified, and the promise of systems biology to yield novel insights is discussed.

  20. Host range and genetic relatedness of Colletotrichum acutatum isolates from fruit crops and leatherleaf fern in Florida.

    PubMed

    MacKenzie, S J; Peres, N A; Barquero, M P; Arauz, L F; Timmer, L W

    2009-05-01

    Isolates of Colletotrichum acutatum were collected from anthracnose-affected strawberry, leatherleaf fern, and Key lime; ripe-rot-affected blueberry; and postbloom fruit drop (PFD)-affected sweet orange in Florida. Additional isolates from ripe-rot-affected blueberry were collected from Georgia and North Carolina and from anthracnose-affected leatherleaf fern in Costa Rica. Pathogenicity tests on blueberry and strawberry fruit; foliage of Key lime, leatherleaf fern, and strawberry; and citrus flowers showed that isolates were highly pathogenic to their host of origin. Isolates were not pathogenic on foliage of heterologous hosts; however, several nonhomologous isolates were mildly or moderately pathogenic to citrus flowers and blueberry isolates were pathogenic to strawberry fruit. Based on sequence data from the internal transcribed spacer (ITS)1-5.8S rRNA-ITS2 region of the rDNA repeat, the glutaraldehyde-3-phosphate dehydrogenase intron 2 (G3PD), and the glutamine synthase intron 2 (GS), isolates from the same host were identical or very similar to each other and distinct from those isolated from other hosts. Isolates from leatherleaf fern in Florida were the only exception. Among these isolates, there were two distinct G3PD and GS sequences that occurred in three of four possible combinations. Only one of these combinations occurred in Costa Rica. Although maximum parsimony trees constructed from genomic regions individually displayed little or no homoplasy, there was a lack of concordance among genealogies that was consistent with a history of recombination. This lack of concordance was particularly evident within a clade containing PFD, Key lime, and leatherleaf fern isolates. Overall, the data indicated that it is unlikely that a pathogenic strain from one of the hosts examined would move to another of these hosts and produce an epidemic.

  1. Genetic evidence from mitochondrial, nuclear, and endosymbiont markers for the evolution of host plant associated species in the aphid genus Hyalopterus (Hemiptera: Aphididae).

    PubMed

    Lozier, Jeffrey D; Roderick, George K; Mills, Nicholas J

    2007-06-01

    Over the past several decades biologists' fascination with plant-herbivore interactions has generated intensive research into the implications of these interactions for insect diversification. The study of closely related phytophagous insect species or populations from an evolutionary perspective can help illuminate ecological and selective forces that drive these interactions. Here we present such an analysis for aphids in the genus Hyalopterus (Hemiptera: Aphididae), a cosmopolitan group that feeds on plants in the genus Prunus (Rosaceae). Hyalopterus currently contains two recognized species associated with different Prunus species, although the taxonomy and evolutionary history of the group is poorly understood. Using mitochondrial COI sequences, 16S rDNA sequences from the aphid endosymbiont Buchnera aphidicola, and nine microsatellite loci we investigated population structure in Hyalopterus from the most commonly used Prunus host species throughout the Mediterranean as well as in California, where the species H. pruni is an invasive pest. We found three deeply divergent lineages structured in large part by specific associations with plum, almond, and peach trees. There was no evidence that geographic or temporal barriers could explain the overall diversity in the genus. Levels of genetic differentiation are consistent with that typically attributed to aphid species and indicate divergence times older than the domestication of Prunus for agriculture. Interestingly, in addition to their typical hosts, aphids from each of the three lineages were frequently found on apricot trees. Apricot also appears to act as a resource mediated hybrid zone for plum and almond associated lineages. Together, results suggest that host plants have played a role in maintaining host-associated differentiation in Hyalopterus for as long as several million years, despite worldwide movement of host plants and the potential for ongoing hybridization.

  2. Host-Parasite Interactions in Chagas Disease: Genetically Unidentical Isolates of a Single Trypanosoma cruzi Strain Identified In Vitro via LSSP-PCR

    PubMed Central

    Nogueira-Paiva, Nívia Carolina; Vieira, Paula Melo de Abreu; Oliveri, Larissa Maris Rezende; Fonseca, Kátia da Silva; Pound-Lana, Gwenaelle; de Oliveira, Maykon Tavares; de Lana, Marta; Veloso, Vanja Maria; Reis, Alexandre Barbosa; Carneiro, Cláudia Martins

    2015-01-01

    The present study aims at establishing whether the diversity in pathogenesis within a genetically diverse host population infected with a single polyclonal strain of Trypanosoma cruzi is due to selection of specific subpopulations within the strain. For this purpose we infected Swiss mice, a genetically diverse population, with the polyclonal strain of Trypanosoma cruzi Berenice-78 and characterized via LSSP-PCR the kinetoplast DNA of subpopulations isolated from blood samples collected from the animals at various times after inoculation (3, 6 and 12 months after inoculation). We examined the biological behavior of the isolates in acellular medium and in vitro profiles of infectivity in Vero cell medium. We compared the characteristics of the isolates with the inoculating strain and with another strain, Berenice 62, isolated from the same patient 16 years earlier. We found that one of the isolates had intermediate behavior in comparison with Berenice-78 and Berenice-62 and a significantly different genetic profile by LSSP-PCR in comparison with the inoculating strain. We hereby demonstrate that genetically distinct Trypanosoma cruzi isolates may be obtained upon experimental murine infection with a single polyclonal Trypanosoma cruzi strain. PMID:26359864

  3. Host islands within the California Northern Channel Islands create fine-scale genetic structure in two sympatric species of the symbiotic ectomycorrhizal fungus Rhizopogon.

    PubMed

    Grubisha, Lisa C; Bergemann, Sarah E; Bruns, Thomas D

    2007-05-01

    We have examined fine-scale genetic structure of the symbiotic ectomycorrhizal fungi Rhizopogon occidentalis and R. vulgaris on two of the California Channel Islands using five and six microsatellite loci, respectively. Both Rhizopogon species are sympatric on Santa Cruz and Santa Rosa Islands and are ectomycorrhizal with bishop pine (Pinus muricata) on both islands or Santa Rosa Island Torrey pine (P. torreyana ssp. insularis) on Santa Rosa. The combination of disjunct pine host distributions and geographic barriers within and among the islands have created highly structured Rhizopogon populations over very short distances (8.5 km on Santa Cruz Island; F(ST) = 0.258, F(ST) = 0.056, R. occidentalis and R. vulgaris, respectively). Both species show similar patterns of genetic differentiation as a result of limited dispersal between host populations as revealed by a significant isolation by distance relationship (r = 0.69, P < 0.04; r = 0.93, P < 0.001, R. occidentalis and R. vulgaris, respectively) and Bayesian clustering analyses, and is most likely a function of the small foraging range of the few mammals that disperse Rhizopogon on these islands and the enormous spore bank characteristic of Rhizopogon species.

  4. Protein expression and genetic structure of the coral Porites lobata in an environmentally extreme Samoan back reef: Does host genotype limit phenotypic plasticity?

    USGS Publications Warehouse

    Barshis, D.J.; Stillman, J.H.; Gates, R.D.; Toonen, R.J.; Smith, L.W.; Birkeland, C.

    2010-01-01

    The degree to which coral reef ecosystems will be impacted by global climate change depends on regional and local differences in corals' susceptibility and resilience to environmental stressors. Here, we present data from a reciprocal transplant experiment using the common reef building coral Porites lobata between a highly fluctuating back reef environment that reaches stressful daily extremes, and a more stable, neighbouring forereef. Protein biomarker analyses assessing physiological contributions to stress resistance showed evidence for both fixed and environmental influence on biomarker response. Fixed influences were strongest for ubiquitin-conjugated proteins with consistently higher levels found in back reef source colonies both pre and post-transplant when compared with their forereef conspecifics. Additionally, genetic comparisons of back reef and forereef populations revealed significant population structure of both the nuclear ribosomal and mitochondrial genomes of the coral host (FST = 0.146 P < 0.0001, FST = 0.335 P < 0.0001 for rDNA and mtDNA, respectively), whereas algal endosymbiont populations were genetically indistinguishable between the two sites. We propose that the genotype of the coral host may drive limitations to the physiological responses of these corals when faced with new environmental conditions. This result is important in understanding genotypic and environmental interactions in the coral algal symbiosis and how corals may respond to future environmental changes. ?? 2010 Blackwell Publishing Ltd.

  5. Inbreeding in stochastic subdivided mating systems: the genetic consequences of host spatial structure, aggregated transmission dynamics and life history characteristics in parasite populations.

    PubMed

    Dharmarajan, Guha

    2015-03-01

    Inbreeding in parasite populations can have important epidemiological and evolutionary implications. However, theoretical models have predominantly focussed on the evolution of parasite populations under strong selection or in epidemic situations, and our understanding of neutral gene dynamics in parasite populations at equilibrium has been limited to verbal arguments or conceptual models. This study focusses on how host-parasite population dynamics affects observed levels of inbreeding in a random sample of parasites from an infinite population of hosts by bridging traditional genetic and parasitological processes utilizing a backward-forward branching Markov process embedded within a flexible statistical framework, the logarithmic-poisson mixture model. My results indicate that levels of inbreeding in parasites are impacted by demographic and/or transmission dynamics (subdivided mating, aggregated transmission dynamics and host spatial structure), and that this inbreeding is poorly estimated by 'equilibrium' levels of inbreeding calculated assuming regular systems of mating. Specifically, the model reveals that at low levels of inbreeding (F ≤ 0.1), equilibrium levels of inbreeding are lower than those observed, while at high levels of inbreeding the opposite pattern occurs. The model also indicates that inbreeding could have important epidemiological implications (e.g., the spread of recessive drug resistance genes) by directly impacting the observed frequency of rare homozygotes in parasite populations. My results indicate that frequencies of rare homozygotes are affected by aggregated transmission dynamics and host spatial structure, and also that an increase in the frequency of rare homozygotes can be caused by a decrease in effective population size solely due to the presence of a subdivided breeding system.

  6. Variation in host specificity and gene content in strains from genetically isolated lineages of the ectomycorrhizal fungus Paxillus involutus s. lat.

    PubMed

    Hedh, Jenny; Johansson, Tomas; Tunlid, Anders

    2009-10-01

    Ectomycorrhizal fungi are known to vary in host range. Some fungi can enter into symbiosis with multiple plant species, while others have restricted host ranges. The aim of this study was to examine variation in host specificity among strains from the basidiomycete Paxillus involutus s. lat. Recent studies have shown that this fungus consists of at least four genetically isolated lineages, phylogenetic species (PS) I (which corresponds to the morphological species Paxillus obscurosporus), PS II (P. involutus s. str.), PS III (Paxillus validus), and PS IV (not yet supported by any reference material). Thirty-five Paxillus strains of PS I to IV were examined in microcosms for their capacity to infect birch (Betula pendula) and spruce (Picea abies). Seventeen strains were compatible and formed mycorrhizae with both tree species. Seven strains were incompatible with both birch and spruce. The gene content in three pairs of incompatible and compatible strains PS I, II, and III were compared using microarray-based comparative genomic hybridizations. Of 4,113 P. involutus gene representatives analyzed, 390 varied in copy numbers in at least one of the three pairwise comparisons. Only three reporters showed significant changes in all three pairwise comparisons, and none of these were changed in a similar way in three comparisons. Our data indicate that changes in host range have occurred frequently and independently among strains in P. obscurosporus, P. involutus s. str., and P. validus. No evidence was obtained demonstrating that these changes have been associated with the gain or loss of similar genes in these three species.

  7. Genetic variability and chromosome-length polymorphisms of the witches' broom pathogen Crinipellis perniciosa from various plant hosts in South America.

    PubMed

    Rincones, Johana; Mazotti, Gabriel D; Griffith, Gareth W; Pomela, Alan; Figueira, Antonio; Leal, Gildemberg A; Queiroz, Marisa V; Pereira, Jorge F; Azevedo, Ricardo A; Pereira, Gonçalo A G; Meinhardt, Lyndel W

    2006-07-01

    Crinipellis perniciosa has been classified into at least four known biotypes associated with members of unrelated plant families. In this study, genetic variability is shown for 27 C (Cacao), 4 S (Solanum), and 7 L biotype (Liana) isolates of C. perniciosa collected from different regions of Brazil and South America. The objective was to investigate the genetic variability of the pathogen in the cacao-producing region of Bahia, Brazil, and elsewhere, through microsatellite analysis, and attempt to identify possible correlations between host specificity and electrophoretic karyotypes. The PCR-banding patterns were found to vary both within and between the different biotypes, and a correlation was established between the PCR-banding patterns and the chromosomal-banding patterns of each isolate. Microsatellite and chromosomal patterns among all of the L and S biotype isolates were distinctly different from the C biotypes analysed. A higher degree of genetic and chromosomal variability was found among C biotype isolates from the Amazon in comparison with C biotype isolates from Bahia, which seems to be comprised of only two main genotypes. This finding has important implications to the current cacao-breeding programme in Brazil.

  8. Whole genome sequencing to identify host genetic risk factors for severe outcomes of hepatitis a virus infection.

    PubMed

    Long, Dustin; Fix, Oren K; Deng, Xutao; Seielstad, Mark; Lauring, Adam S

    2014-10-01

    Acute liver failure is a severe, but rare, outcome of hepatitis A virus infection. Unusual presentations of prevalent infections have often been attributed to pathogen-specific immune deficits that exhibit Mendelian inheritance. Genome-wide resequencing of unrelated cases has proven to be a powerful approach for identifying highly penetrant risk alleles that underlie such syndromes. Rare mutations likely to affect protein expression or function can be identified from sequence data, and their association with a similarly rare phenotype rests on their existence in multiple affected individuals. A rare or novel sequence variant that is enriched to a significant degree in a genetically diverse cohort suggests a candidate susceptibility allele. Whole genome sequencing of ten individuals from ethnically diverse backgrounds with HAV-associated acute liver failure was performed. A set of rational filtering criteria was used to identify genetic variants that are rare in the population, but enriched in this cohort. Single nucleotide polymorphisms, insertions, and deletions were considered and autosomal dominant, autosomal recessive, and polygenic models were applied. Analysis of the protein-coding exome identified no single gene with putatively deleterious mutations shared by multiple individuals, arguing against a simple Mendelian model of inheritance. A number of rare variants were significantly enriched in this cohort, consistent with a complex and genetically heterogeneous trait. Several of the variants identified in this genome-wide study lie within genes important to hepatic pathophysiology and are candidate susceptibility alleles for hepatitis A virus infection.

  9. Change in Emiliania huxleyi Virus Assemblage Diversity but Not in Host Genetic Composition during an Ocean Acidification Mesocosm Experiment

    PubMed Central

    Highfield, Andrea; Joint, Ian; Gilbert, Jack A.; Crawfurd, Katharine J.; Schroeder, Declan C.

    2017-01-01

    Effects of elevated pCO2 on Emiliania huxleyi genetic diversity and the viruses that infect E. huxleyi (EhVs) have been investigated in large volume enclosures in a Norwegian fjord. Triplicate enclosures were bubbled with air enriched with CO2 to 760 ppmv whilst the other three enclosures were bubbled with air at ambient pCO2; phytoplankton growth was initiated by the addition of nitrate and phosphate. E. huxleyi was the dominant coccolithophore in all enclosures, but no difference in genetic diversity, based on DGGE analysis using primers specific to the calcium binding protein gene (gpa) were detected in any of the treatments. Chlorophyll concentrations and primary production were lower in the three elevated pCO2 treatments than in the ambient treatments. However, although coccolithophores numbers were reduced in two of the high-pCO2 treatments; in the third, there was no suppression of coccolithophores numbers, which were very similar to the three ambient treatments. In contrast, there was considerable variation in genetic diversity in the EhVs, as determined by analysis of the major capsid protein (mcp) gene. EhV diversity was much lower in the high-pCO2 treatment enclosure that did not show inhibition of E. huxleyi growth. Since virus infection is generally implicated as a major factor in terminating phytoplankton blooms, it is suggested that no study of the effect of ocean acidification in phytoplankton can be complete if it does not include an assessment of viruses. PMID:28282890

  10. Within Host Evolution Selects for a Dominant Genotype of Mycobacterium tuberculosis while T Cells Increase Pathogen Genetic Diversity

    PubMed Central

    Copin, Richard; Louie, Eddie; Escuyer, Vincent; Gagneux, Sebastien; Palmer, Guy H.

    2016-01-01

    Molecular epidemiological assessments, drug treatment optimization, and development of immunological interventions all depend on understanding pathogen adaptation and genetic variation, which differ for specific pathogens. Mycobacterium tuberculosis is an exceptionally successful human pathogen, yet beyond knowledge that this bacterium has low overall genomic variation but acquires drug resistance mutations, little is known of the factors that drive its population genomic characteristics. Here, we compared the genetic diversity of the bacteria that established infection to the bacterial populations obtained from infected tissues during murine M. tuberculosis pulmonary infection and human disseminated M. bovis BCG infection. We found that new mutations accumulate during in vitro culture, but that in vivo, purifying selection against new mutations dominates, indicating that M. tuberculosis follows a dominant lineage model of evolution. Comparing bacterial populations passaged in T cell-deficient and immunocompetent mice, we found that the presence of T cells is associated with an increase in the diversity of the M. tuberculosis genome. Together, our findings put M. tuberculosis genetic evolution in a new perspective and clarify the impact of T cells on sequence diversity of M. tuberculosis. PMID:27973588

  11. Evolutionary genetics and vector adaptation of recombinant viruses of the western equine encephalitis antigenic complex provides new insights into alphavirus diversity and host switching

    PubMed Central

    Allison, Andrew B.; Stallknecht, David E.; Holmes, Edward C.

    2014-01-01

    Western equine encephalitis virus (WEEV), Highlands J virus (HJV), and Fort Morgan virus (FMV) are the sole representatives of the WEE antigenic complex of the genus Alphavirus, family Togaviridae, that are endemic to North America. All three viruses have their ancestry in a recombination event involving eastern equine encephalitis virus (EEEV) and a Sindbis (SIN)-like virus that gave rise to a chimeric alphavirus that subsequently diversified into the present-day WEEV, HJV, and FMV. Here, we present a comparative analysis of the genetic, ecological, and evolutionary relationships among these recombinant-origin viruses, including the description of a nsP4 polymerase mutation in FMV that allows it to circumvent the host range barrier to Asian tiger mosquito cells, a vector species that is normally refractory to infection. Notably, we also provide evidence that the recombination event that gave rise to these three WEEV antigenic complex viruses may have occurred in North America. PMID:25463613

  12. Evolutionary genetics and vector adaptation of recombinant viruses of the western equine encephalitis antigenic complex provides new insights into alphavirus diversity and host switching.

    PubMed

    Allison, Andrew B; Stallknecht, David E; Holmes, Edward C

    2015-01-01

    Western equine encephalitis virus (WEEV), Highlands J virus (HJV), and Fort Morgan virus (FMV) are the sole representatives of the WEE antigenic complex of the genus Alphavirus, family Togaviridae, that are endemic to North America. All three viruses have their ancestry in a recombination event involving eastern equine encephalitis virus (EEEV) and a Sindbis (SIN)-like virus that gave rise to a chimeric alphavirus that subsequently diversified into the present-day WEEV, HJV, and FMV. Here, we present a comparative analysis of the genetic, ecological, and evolutionary relationships among these recombinant-origin viruses, including the description of a nsP4 polymerase mutation in FMV that allows it to circumvent the host range barrier to Asian tiger mosquito cells, a vector species that is normally refractory to infection. Notably, we also provide evidence that the recombination event that gave rise to these three WEEV antigenic complex viruses may have occurred in North America.

  13. Genetic tools link long-term demographic and life-history traits of anemonefish to their anemone hosts

    NASA Astrophysics Data System (ADS)

    Salles, Océane C.; Saenz-Agudelo, Pablo; Almany, Glenn R.; Berumen, Michael L.; Thorrold, Simon R.; Jones, Geoffrey P.; Planes, Serge

    2016-12-01

    The life-history traits and population dynamics of species are increasingly being attributed to the characteristics of their preferred habitats. While coral reef fish are often strongly associated with particular habitats, long-term studies establishing the demographic and life-history consequences of occupying different reef substrata are rare and no studies have monitored individuals in situ over their lifetime and determined the fate of their offspring. Here, we documented a quasi-turnover and local reproductive success for an entire population of orange clownfish ( Amphiprion percula) from Kimbe Island, Papua New Guinea, by taking bi-annual samples of DNA over a 10-yr period (2003-2013). We compared demographic and life-history traits of individuals living on two host anemone species, Heteractis magnifica and Stichodactyla gigantea, including female size, adult continued presence (a proxy for relative longevity range), early post-settlement growth, the number of eggs per clutch and `local' reproductive success (defined for each adult as the number of offspring returning to the natal population). Our results indicate that while the relative longevity of adults was similar on both host anemone species, females living in H. magnifica were larger than females in S. gigantea. However, despite females growing larger and producing more eggs on H. magnifica, we found that local reproductive success was significantly higher for clownfish living in S. gigantea. Life-history traits also exhibited local spatial variation, with higher local reproductive success recorded for adults living on S. gigantea on the eastern side of the island. Our findings support a `silver-spoon' hypothesis that predicts individuals that are fortunate enough to recruit into good habitat and location will be rewarded with higher long-term reproductive success and will make a disproportionate contribution to population renewal.

  14. Host genetic variations in glutathione-S-transferases, superoxide dismutases and catalase genes influence susceptibility to malaria infection in an Indian population.

    PubMed

    Fernandes, Rayzel C; Hasan, Marriyah; Gupta, Himanshu; Geetha, K; Rai, Padmalatha S; Hande, Manjunath H; D'Souza, Sydney C; Adhikari, Prabha; Brand, Angela; Satyamoorthy, Kapaettu

    2015-06-01

    Antioxidant enzymes can contribute to disease susceptibility or determine response to therapy in individuals with malaria. Genetic variations due to polymorphisms in host genes encoding antioxidant enzymes such as glutathione S-transferases-theta, mu, pi (GSTT, GSTM, GSTP), superoxide dismutases (SOD) and catalase (CAT), may therefore, influence inter-individual response to malaria pathology and propensity of infection caused by Plasmodium vivax (Pv) and Plasmodium falciparum (Pf). Therefore, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing, we investigated the association of deletions of GSTT1 and GSTM1, single nucleotide polymorphisms (SNPs) of GSTP1 (rs1695), SOD1 (rs2234694), SOD2 (rs4880, rs1141718), SOD3 (rs2536512) and CAT (rs1001179) in individuals infected with Pf (n = 100) and Pv (n = 100) against healthy controls (n = 150). Our data suggest a significant role for GSTM1 deletions in complicated Pv (p = 0.0007) malaria with ODDs ratio 3.8 [with 95 % confidence interval (CI) 1.9-7.4]. The results also indicated that polymorphisms present in GSTP1, SOD1 and CAT genes may be associated with malaria susceptibility (p < 0.05), whereas SOD3 polymorphism may play a role in malarial resistance (p < 0.05). In addition, we observed significant SNP-SNP interactions with synergistic genetic effects in SOD2, SOD3 and CAT genes for Pv and in SOD2 and SOD3 genes for Pf. In conclusion, our results provide convincing evidence for a relationship between polymorphisms in host antioxidant enzymes and susceptibility to malaria infection.

  15. Development of allergic airway disease in mice following antibiotic therapy and fungal microbiota increase: role of host genetics, antigen, and interleukin-13.

    PubMed

    Noverr, Mairi C; Falkowski, Nicole R; McDonald, Rod A; McKenzie, Andrew N; Huffnagle, Gary B

    2005-01-01

    Lending support to the hygiene hypothesis, epidemiological studies have demonstrated that allergic disease correlates with widespread use of antibiotics and alterations in fecal microbiota ("microflora"). Antibiotics also lead to overgrowth of the yeast Candida albicans, which can secrete potent prostaglandin-like immune response modulators, from the microbiota. We have recently developed a mouse model of antibiotic-induced gastrointestinal microbiota disruption that is characterized by stable increases in levels of gastrointestinal enteric bacteria and Candida. Using this model, we have previously demonstrated that microbiota disruption can drive the development of a CD4 T-cell-mediated airway allergic response to mold spore challenge in immunocompetent C57BL/6 mice without previous systemic antigen priming. The studies presented here address important questions concerning the universality of the model. To investigate the role of host genetics, we tested BALB/c mice. As with C57BL/6 mice, microbiota disruption promoted the development of an allergic response in the lungs of BALB/c mice upon subsequent challenge with mold spores. In addition, this allergic response required interleukin-13 (IL-13) (the response was absent in IL-13(-/-) mice). To investigate the role of antigen, we subjected mice with disrupted microbiota to intranasal challenge with ovalbumin (OVA). In the absence of systemic priming, only mice with altered microbiota developed airway allergic responses to OVA. The studies presented here demonstrate that the effects of microbiota disruption are largely independent of host genetics and the nature of the antigen and that IL-13 is required for the airway allergic response that follows microbiota disruption.

  16. Genetic variability in G2 and F2 region between biological clones of human respiratory syncytial virus with or without host immune selection pressure.

    PubMed

    Moraes, Claudia Trigo Pedroso; Oliveira, Danielle Bruna Leal; Campos, Angelica Cristine Almeida; Bosso, Patricia Alves; Lima, Hildener Nogueira; Stewien, Klaus Eberhard; Gilio, Alfredo Elias; Vieira, Sandra Elisabete; Botosso, Viviane Fongaro; Durigon, Edison Luiz

    2015-02-01

    Human respiratory syncytial virus (HRSV) is an important respiratory pathogens among children between zero-five years old. Host immunity and viral genetic variability are important factors that can make vaccine production difficult. In this work, differences between biological clones of HRSV were detected in clinical samples in the absence and presence of serum collected from children in the convalescent phase of the illness and from their biological mothers. Viral clones were selected by plaque assay in the absence and presence of serum and nucleotide sequences of the G2 and F2 genes of HRSV biological clones were compared. One non-synonymous mutation was found in the F gene (Ile5Asn) in one clone of an HRSV-B sample and one non-synonymous mutation was found in the G gene (Ser291Pro) in four clones of the same HRSV-B sample. Only one of these clones was obtained after treatment with the child's serum. In addition, some synonymous mutations were determined in two clones of the HRSV-A samples. In conclusion, it is possible that minor sequences could be selected by host antibodies contributing to the HRSV evolutionary process, hampering the development of an effective vaccine, since we verify the same codon alteration in absence and presence of human sera in individual clones of BR-85 sample.

  17. Host genetic resistance to root-knot nematodes, Meloidogyne spp., in Solanaceae: from genes to the field.

    PubMed

    Barbary, Arnaud; Djian-Caporalino, Caroline; Palloix, Alain; Castagnone-Sereno, Philippe

    2015-12-01

    Root-knot nematodes (RKNs) heavily damage most solanaceous crops worldwide. Fortunately, major resistance genes are available in a number of plant species, and their use provides a safe and economically relevant strategy for RKN control. From a structural point of view, these genes often harbour NBS-LRR motifs (i.e. a nucleotide binding site and a leucine rich repeat region near the carboxy terminus) and are organised in syntenic clusters in solanaceous genomes. Their introgression from wild to cultivated plants remains a challenge for breeders, although facilitated by marker-assisted selection. As shown with other pathosystems, the genetic background into which the resistance genes are introgressed is of prime importance to both the expression of the resistance and its durability, as exemplified by the recent discovery of quantitative trait loci conferring quantitative resistance to RKNs in pepper. The deployment of resistance genes at a large scale may result in the emergence and spread of virulent nematode populations able to overcome them, as already reported in tomato and pepper. Therefore, careful management of the resistance genes available in solanaceous crops is crucial to avoid significant reduction in the duration of RKN genetic control in the field. From that perspective, only rational management combining breeding and cultivation practices will allow the design and implementation of innovative, sustainable crop production systems that protect the resistance genes and maintain their durability.

  18. Genetic and grade and tonnage models for sandstone-hosted roll-type uranium deposits, Texas Coastal Plain, USA

    USGS Publications Warehouse

    Hall, Susan M.; Mihalasky, Mark J.; Tureck, Kathleen; Hammarstrom, Jane M.; Hannon, Mark

    2017-01-01

    The coincidence of a number of geologic and climatic factors combined to create conditions favorable for the development of mineable concentrations of uranium hosted by Eocene through Pliocene sandstones in the Texas Coastal Plain. Here 254 uranium occurrences, including 169 deposits, 73 prospects, 6 showings and 4 anomalies, have been identified. About 80 million pounds of U3O8 have been produced and about 60 million pounds of identified producible U3O8 remain in place. The development of economic roll-type uranium deposits requires a source, large-scale transport of uranium in groundwater, and deposition in reducing zones within a sedimentary sequence. The weight of the evidence supports a source from thick sequences of volcanic ash and volcaniclastic sediment derived mostly from the Trans-Pecos volcanic field and Sierra Madre Occidental that lie west of the region. The thickest accumulations of source material were deposited and preserved south and west of the San Marcos arch in the Catahoula Formation. By the early Oligocene, a formerly uniformly subtropical climate along the Gulf Coast transitioned to a zoned climate in which the southwestern portion of Texas Coastal Plain was dry, and the eastern portion humid. The more arid climate in the southwestern area supported weathering of volcanic ash source rocks during pedogenesis and early diagenesis, concentration of uranium in groundwater and movement through host sediments. During the middle Tertiary Era, abundant clastic sediments were deposited in thick sequences by bed-load dominated fluvial systems in long-lived channel complexes that provided transmissive conduits favoring transport of uranium-rich groundwater. Groundwater transported uranium through permeable sandstones that were hydrologically connected with source rocks, commonly across formation boundaries driven by isostatic loading and eustatic sea level changes. Uranium roll fronts formed as a result of the interaction of uranium-rich groundwater

  19. The genomes of closely related Pantoea ananatis maize seed endophytes having different effects on the host plant differ in secretion system genes and mobile genetic elements

    PubMed Central

    Sheibani-Tezerji, Raheleh; Naveed, Muhammad; Jehl, Marc-André; Sessitsch, Angela; Rattei, Thomas; Mitter, Birgit

    2015-01-01

    The seed as a habitat for microorganisms is as yet under-explored and has quite distinct characteristics as compared to other vegetative plant tissues. In this study, we investigated three closely related P. ananatis strains (named S6, S7, and S8), which were isolated from maize seeds of healthy plants. Plant inoculation experiments revealed that each of these strains exhibited a different phenotype ranging from weak pathogenic (S7), commensal (S8), to a beneficial, growth-promoting effect (S6) in maize. We performed a comparative genomics analysis in order to find genetic determinants responsible for the differences observed. Recent studies provided exciting insight into the genetic drivers of niche adaption and functional diversification of the genus Pantoea. However, we report here for the first time on the analysis of P. ananatis strains colonizing the same ecological niche but showing distinct interaction strategies with the host plant. Our comparative analysis revealed that genomes of these three strains are highly similar. However, genomic differences in genes encoding protein secretion systems and putative effectors, and transposase/integrases/phage related genes could be observed. PMID:26029184

  20. The genomes of closely related Pantoea ananatis maize seed endophytes having different effects on the host plant differ in secretion system genes and mobile genetic elements.

    PubMed

    Sheibani-Tezerji, Raheleh; Naveed, Muhammad; Jehl, Marc-André; Sessitsch, Angela; Rattei, Thomas; Mitter, Birgit

    2015-01-01

    The seed as a habitat for microorganisms is as yet under-explored and has quite distinct characteristics as compared to other vegetative plant tissues. In this study, we investigated three closely related P. ananatis strains (named S6, S7, and S8), which were isolated from maize seeds of healthy plants. Plant inoculation experiments revealed that each of these strains exhibited a different phenotype ranging from weak pathogenic (S7), commensal (S8), to a beneficial, growth-promoting effect (S6) in maize. We performed a comparative genomics analysis in order to find genetic determinants responsible for the differences observed. Recent studies provided exciting insight into the genetic drivers of niche adaption and functional diversification of the genus Pantoea. However, we report here for the first time on the analysis of P. ananatis strains colonizing the same ecological niche but showing distinct interaction strategies with the host plant. Our comparative analysis revealed that genomes of these three strains are highly similar. However, genomic differences in genes encoding protein secretion systems and putative effectors, and transposase/integrases/phage related genes could be observed.

  1. Biosynthesis of Polymyxins B, E, and P Using Genetically Engineered Polymyxin Synthetases in the Surrogate Host Bacillus subtilis.

    PubMed

    Kim, Se-Yu; Park, Soo-Young; Choi, Soo-Keun; Park, Seung-Hwan

    2015-07-01

    The development of diverse polymyxin derivatives is needed to solve the toxicity and resistance problems of polymyxins. However, no platform has generated polymyxin derivatives by genetically engineering a polymyxin synthetase, which is a nonribosomal peptide synthetase. In this study, we present a two-step approach for the construction of engineered polymyxin synthetases by substituting the adenylation (A) domains of polymyxin A synthetase, which is encoded by the pmxABCDE gene cluster of Paenibacillus polymyxa E681. First, the seventh L-threonine-specific A-domain region in pmxA was substituted with the Lleucine- specific A-domain region obtained from P. polymyxa ATCC21830 to make polymyxin E synthetase, and then the sixth D-leucine-specific A-domain region (A6-D-Leu-domain) was substituted with the D-phenylalanine-specific A-domain region (A6-D-Phe-domain) obtained from P. polymyxa F4 to make polymyxin B synthetase. This step was performed in Escherichia coli on a pmxA-containing fosmid, using the lambda Red recombination system and the sacB gene as a counter-selectable marker. Next, the modified pmxA gene was fused to pmxBCDE on the chromosome of Bacillus subtilis BSK4dA, and the resulting recombinant strains BSK4-PB and BSK4-PE were confirmed to produce polymyxins B and E, respectively. We also succeeded in constructing the B. subtilis BSK4-PP strain, which produces polymyxin P, by singly substituting the A6-D-Leu-domain with the A6-D-Phe-domain. This is the first report in which polymyxin derivatives were generated by genetically engineering polymyxin synthetases. The two recombinant B. subtilis strains will be useful for improving the commercial production of polymyxins B and E, and they will facilitate the generation of novel polymyxin derivatives.

  2. Community composition, host range and genetic structure of the fungal entomopathogen Beauveria in adjoining agricultural and seminatural habitats.

    PubMed

    Meyling, Nicolai V; Lübeck, Mette; Buckley, Ellen P; Eilenberg, Jørgen; Rehner, Stephen A

    2009-03-01

    Although intensively investigated for biological control of insect pests, little is known about the ecology of the fungal entomopathogenic genus Beauveria in natural or agricultural habitats. In this study, we used molecular phylogenetic and genotypic information to infer species diversity, reproductive potential and genetic structure of Beauveria occurring within a single arable field and bordering hedgerow in Denmark. Isolates were sampled from cultivated field and hedgerow soils, from insects harbouring latent fungal infections, and from the phylloplanes of three plant species common in the hedgerow flora. A nuclear phylogeny of this local Beauveria assemblage resolved seven phylogenetic species, including (i) five phylogenetic species within Beauveria bassiana sensu stricto; (ii) Clade C, a taxonomically uncharacterized species that is morphologically indistinguishable but phylogenetically distant from B. bassiana s.s.; and (iii) Beauveria brongniartii. All seven species were present throughout the hedgerow habitat, including as infections in insects. Significantly, only B. bassiana s.s. phylogenetic species Eu_1 was isolated from tilled soils. Mating type polymerase chain reaction assays demonstrated that all five B. bassiana s.s. phylogenetic species possess bipolar outcrossing mating systems. Of these, only the Eu_1 population contained two mating types; however, a 31:2 skew in MAT1:MAT2 mating types suggests a low frequency of sexual reproduction in this population. The four remaining B. bassiana s.s. phylogenetic species were fixed for single mating types and these populations are evidently clonal. Multilocus microsatellite genotyping revealed polymorphism in all five phylogenetic species of B. bassiana s.s.; however, all show evidence of clonal genetic structure.

  3. Plant resistance to aphid feeding: behavioral, physiological, genetic and molecular cues regulate aphid host selection and feeding.

    PubMed

    Smith, C Michael; Chuang, Wen-Po

    2014-04-01

    Aphids damage major world food and fiber crops through direct feeding and transmission of plant viruses. Fortunately, the development of many aphid-resistant crop plants has provided both ecological and economic benefits to food production. Plant characters governing aphid host selection often dictate eventual plant resistance or susceptibility to aphid herbivory, and these phenotypic characters have been successfully used to map aphid resistance genes. Aphid resistance is often inherited as a dominant trait, but is also polygenic and inherited as recessive or incompletely dominant traits. Most aphid-resistant cultivars exhibit constitutively expressed defenses, but some cultivars exhibit dramatic aphid-induced responses, resulting in the overexpression of large ensembles of putative aphid resistance genes. Two aphid resistance genes have been cloned. Mi-1.2, an NBS-LRR gene from wild tomato, confers resistance to potato aphid and three Meloidogyne root-knot nematode species, and Vat, an NBS-LRR gene from melon, controls resistance to the cotton/melon aphid and to some viruses. Virulence to aphid resistance genes of plants occurs in 17 aphid species--more than half of all arthropod biotypes demonstrating virulence. The continual appearance of aphid virulence underscores the need to identify new sources of resistance of diverse sequence and function in order to delay or prevent biotype development.

  4. The role of CD1d-restricted NKT cells in the clearance of Pseudomonas aeruginosa from the lung is dependent on the host genetic background.

    PubMed

    Benoit, Patrick; Sigounas, Vaia Yioula; Thompson, Jenna L; van Rooijen, Nico; Poynter, Matthew E; Wargo, Matthew J; Boyson, Jonathan E

    2015-06-01

    Pseudomonas aeruginosa is an important human opportunistic pathogen, accounting for a significant fraction of hospital-acquired lung infections. CD1d-restricted NKT cells comprise an unusual innate-like T cell subset that plays important roles in both bacterial and viral infections. Previous reports have differed in their conclusions regarding the role of NKT cells in clearance of P. aeruginosa from the lung. Since there is significant strain-dependent variation in NKT cell number and function among different inbred strains of mice, we investigated whether the role of NKT cells was dependent on the host genetic background. We found that NKT cells did indeed play a critical role in the clearance of P. aeruginosa from the lungs of BALB/c mice but that they played no discernible role in clearance from the lungs of C57BL/6 mice. We found that the strain-dependent role of NKT cells was associated with significant strain-dependent differences in cytokine production by lung NKT cells and that impaired clearance of P. aeruginosa in BALB/c CD1d(-/-) mice was associated with an increase in neutrophil influx to the lung and increased levels of proinflammatory cytokines and chemokines after infection. Finally, we found that the role of alveolar macrophages was also dependent on the genetic background. These data provide further support for a model in which the unusually high level of variability in NKT cell number and function among different genetic backgrounds may be an important contributor to infectious-disease susceptibility and pathology.

  5. Sex-Biased Transcriptome of Schistosoma mansoni: Host-Parasite Interaction, Genetic Determinants and Epigenetic Regulators Are Associated with Sexual Differentiation

    PubMed Central

    Picard, Marion A. L.; Boissier, Jérôme; Roquis, David; Grunau, Christoph; Allienne, Jean-François; Duval, David; Toulza, Eve; Arancibia, Nathalie; Caffrey, Conor R.; Long, Thavy; Nidelet, Sabine; Rohmer, Marine; Cosseau, Céline

    2016-01-01

    Background Among more than 20,000 species of hermaphroditic trematodes, Schistosomatidae are unusual since they have evolved gonochorism. In schistosomes, sex is determined by a female heterogametic system, but phenotypic sexual dimorphism appears only after infection of the vertebrate definitive host. The completion of gonad maturation occurs even later, after pairing. To date, the molecular mechanisms that trigger the sexual differentiation in these species remain unknown, and in vivo studies on the developing schistosomulum stages are lacking. To study the molecular basis of sex determination and sexual differentiation in schistosomes, we investigated the whole transcriptome of the human parasite Schistosoma mansoni in a stage- and sex-comparative manner. Methodology/ Principal Findings We performed a RNA-seq on males and females for five developmental stages: cercariae larvae, three in vivo schistosomulum stages and adults. We detected 7,168 genes differentially expressed between sexes in at least one of the developmental stages, and 4,065 of them were functionally annotated. Transcriptome data were completed with H3K27me3 histone modification analysis using ChIP-Seq before (in cercariae) and after (in adults) the phenotypic sexual dimorphism appearance. In this paper we present (i) candidate determinants of the sexual differentiation, (ii) sex-biased players of the interaction with the vertebrate host, and (iii) different dynamic of the H3K27me3 histone mark between sexes as an illustration of sex-biased epigenetic landscapes. Conclusions/ Significance Our work presents evidence that sexual differentiation in S. mansoni is accompanied by distinct male and female transcriptional landscapes of known players of the host-parasite crosstalk, genetic determinants and epigenetic regulators. Our results suggest that such combination could lead to the optimized sexual dimorphism of this parasitic species. As S. mansoni is pathogenic for humans, this study represents a

  6. A Statistical Framework for Microbial Source Attribution: Measuring Uncertainty in Host Transmission Events Inferred from Genetic Data (Part 2 of a 2 Part Report)

    SciTech Connect

    Allen, J; Velsko, S

    2009-11-16

    This report explores the question of whether meaningful conclusions can be drawn regarding the transmission relationship between two microbial samples on the basis of differences observed between the two sample's respective genomes. Unlike similar forensic applications using human DNA, the rapid rate of microbial genome evolution combined with the dynamics of infectious disease require a shift in thinking on what it means for two samples to 'match' in support of a forensic hypothesis. Previous outbreaks for SARS-CoV, FMDV and HIV were examined to investigate the question of how microbial sequence data can be used to draw inferences that link two infected individuals by direct transmission. The results are counter intuitive with respect to human DNA forensic applications in that some genetic change rather than exact matching improve confidence in inferring direct transmission links, however, too much genetic change poses challenges, which can weaken confidence in inferred links. High rates of infection coupled with relatively weak selective pressure observed in the SARS-CoV and FMDV data lead to fairly low confidence for direct transmission links. Confidence values for forensic hypotheses increased when testing for the possibility that samples are separated by at most a few intermediate hosts. Moreover, the observed outbreak conditions support the potential to provide high confidence values for hypothesis that exclude direct transmission links. Transmission inferences are based on the total number of observed or inferred genetic changes separating two sequences rather than uniquely weighing the importance of any one genetic mismatch. Thus, inferences are surprisingly robust in the presence of sequencing errors provided the error rates are randomly distributed across all samples in the reference outbreak database and the novel sequence samples in question. When the number of observed nucleotide mutations are limited due to characteristics of the outbreak or the

  7. Primary alveolar echinococcosis: course of larval development and antibody responses in intermediate host rodents with different genetic backgrounds after oral infection with eggs of Echinococcus multilocularis.

    PubMed

    Matsumoto, Jun; Kouguchi, Hirokazu; Oku, Yuzaburo; Yagi, Kinpei

    2010-09-01

    We investigated parasite establishment, subsequent larval development and antibody responses in gerbils, cotton rats and 4 inbred mouse strains until 16 weeks post inoculation (p.i.) with 200 eggs of Echinococcus multilocularis. The rate of parasite establishment in the liver determined at 4 weeks p.i. was highest in DBA/2, followed by AKR/N, C57BL/10 and C57BL/6 mice, whereas gerbils harboured few parasite foci. The accurate number of liver lesions in cotton rats could not be determined due to rapid growth and advanced multivesiculation of the parasite observed at 2 weeks p.i. The course of larval development was most advanced in DBA/2 mice with mature protoscolex formation at 16 weeks p.i., followed by AKR/N harbouring metacestodes with sparsely distributed immature protoscoleces. On the other hand, C57BL/6 and C57BL/10 mice had infertile metacestodes without any protoscolex formation. The parasite growth in mice was totally slower than those in gerbils and cotton rats. Specific IgG and IgM responses against 3 types of native crude antigens of larval E. multilocularis were evaluated using somatic extracts of and vesicle fluid of metacestode, and somatic extracts from purified protoscoleces. The 4 mouse strains demonstrated basically similar kinetics with apparent IgG and IgM increases at 9 weeks p.i. and thereafter, except C57BL/10, exhibited higher levels of IgM against crude antigens at some time point of infection. On the other hand, a follow-up determination of specific IgG and IgM levels against recombinant antigens from larval E. multilocularis revealed that each mouse strain showed different antibody-level kinetics. The findings in the present study demonstrate that the course of host-parasite interactions in primary alveolar echinococcosis, caused by larval E. multilocularis, clearly varies among intermediate host rodents with different genetic backgrounds.

  8. Genetics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genus Capsicum represents one of several well characterized Solanaceous genera. A wealth of classical and molecular genetics research is available for the genus. Information gleaned from its cultivated relatives, tomato and potato, provide further insight for basic and applied studies. Early ...

  9. Genetics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maintaining genetic variation in wild populations of Arctic organisms is fundamental to the long-term persistence of high latitude biodiversity. Variability is important because it provides options for species to respond to changing environmental conditions and novel challenges such as emerging path...

  10. Dual Role of Interleukin-4 (IL-4) in Pulmonary Paracoccidioidomycosis: Endogenous IL-4 Can Induce Protection or Exacerbation of Disease Depending on the Host Genetic Pattern

    PubMed Central

    Arruda, Celina; Valente-Ferreira, Rita C.; Pina, Adriana; Kashino, Suely S.; Fazioli, Raquel A.; Vaz, Celidéia A. C.; Franco, Marcello F.; Keller, Alexandre C.; Calich, Vera L. G.

    2004-01-01

    Resistance to paracoccidioidomycosis, the most important endemic mycosis in Latin America, is thought to be primarily mediated by cellular immunity and the production of gamma interferon. To assess the role of interleukin-4 (IL-4), a Th2 cytokine, pulmonary paracoccidioidomycosis in IL-4-depleted susceptible (B10.A) and intermediate (C57BL/6) mice was studied. Two different protocols were used to neutralize endogenous IL-4 in B10.A mice: 1 mg of anti-IL-4 monoclonal antibody (MAb)/week and 8 mg 1 day before intratracheal infection with 106 Paracoccidioides brasiliensis yeast cells. Unexpectedly, both protocols enhanced pulmonary infection but did not alter the levels of pulmonary cytokines and specific antibodies. Since in a previous work it was verified that C57BL/6 mice genetically deficient in IL-4 were more resistant to P. brasiliensis infection, we also investigated the effect of IL-4 depletion in this mouse strain. Treatment with the MAb at 1 mg/week led to less severe pulmonary disease associated with impaired synthesis of Th2 cytokines in the lungs and liver of control C57BL/6 mice. Conversely, in IL-4-depleted C57BL/6 mice, increased levels of tumor necrosis factor alpha and IL-12 were found in the lungs and liver, respectively. In addition, higher levels of immunoglobulin G2a (IgG2a) and lower levels of IgG1 antibodies were produced by IL-4-depleted mice than by control mice. Lung pathologic findings were equivalent in IL-4-depleted and untreated B10.A mice. In IL-4-depleted C57BL/6 mice, however, smaller and well-organized granulomas replaced the more extensive lesions that developed in untreated mice. These results clearly showed that IL-4 can have a protective or a disease-promoting effect in pulmonary paracoccidioidomycosis depending on the genetic background of the host. PMID:15213137

  11. Genetically modified human CD4(+) T cells can be evaluated in vivo without lethal graft-versus-host disease.

    PubMed

    Ali, Riyasat; Babad, Jeffrey; Follenzi, Antonia; Gebe, John A; Brehm, Michael A; Nepom, Gerald T; Shultz, Leonard D; Greiner, Dale L; DiLorenzo, Teresa P

    2016-08-01

    Adoptive cell immunotherapy for human diseases, including the use of T cells modified to express an anti-tumour T-cell receptor (TCR) or chimeric antigen receptor, is showing promise as an effective treatment modality. Further advances would be accelerated by the availability of a mouse model that would permit human T-cell engineering protocols and proposed genetic modifications to be evaluated in vivo. NOD-scid IL2rγ(null) (NSG) mice accept the engraftment of mature human T cells; however, long-term evaluation of transferred cells has been hampered by the xenogeneic graft-versus-host disease (GVHD) that occurs soon after cell transfer. We modified human primary CD4(+) T cells by lentiviral transduction to express a human TCR that recognizes a pancreatic beta cell-derived peptide in the context of HLA-DR4. The TCR-transduced cells were transferred to NSG mice engineered to express HLA-DR4 and to be deficient for murine class II MHC molecules. CD4(+) T-cell-depleted peripheral blood mononuclear cells were also transferred to facilitate engraftment. The transduced cells exhibited long-term survival (up to 3 months post-transfer) and lethal GVHD was not observed. This favourable outcome was dependent upon the pre-transfer T-cell transduction and culture conditions, which influenced both the kinetics of engraftment and the development of GVHD. This approach should now permit human T-cell transduction protocols and genetic modifications to be evaluated in vivo, and it should also facilitate the development of human disease models that incorporate human T cells.

  12. Multi-locus genotypes of Enterocytozoon bieneusi in captive Asiatic black bears in southwestern China: High genetic diversity, broad host range, and zoonotic potential

    PubMed Central

    Cao, Xuefeng; Song, Yuan; Wang, Wuyou; Huang, Xiangming; Liu, Xuehan; Hu, Yanchun; Fu, Hualin; He, Min; Wang, Ya; Zhang, Yue; Wu, Kongju; Peng, Guangneng

    2017-01-01

    Enterocytozoon bieneusi is an obligate eukaryotic intracellular parasite that infects a wide variety of vertebrate and invertebrate hosts. Although considerable research has been conducted on this organism, relatively little information is available on the occurrence of E. bieneusi in captive Asiatic black bears. The present study was performed to determine the prevalence, genetic diversity, and zoonotic potential of E. bieneusi in captive Asiatic black bears in zoos in southwestern China. Fecal specimens from Asiatic black bears in four zoos, located in four different cities, were collected and analyzed for the prevalence of E. bieneusi. The average prevalence of E. bieneusi was 27.4% (29/106), with the highest prevalence in Guiyang Zoo (36.4%, 16/44). Altogether, five genotypes of E. bieneusi were identified among the 29 E. bieneusi-positive samples, including three known genotypes (CHB1, SC02, and horse2) and two novel genotypes named ABB1 and ABB2. Multi-locus sequence typing using three microsatellites (MS1, MS3, and MS7) and one minisatellite (MS4) revealed V, III, V, and IV genotypes at these four loci, respectively. Phylogenetic analysis showed that the genotypes SC02 and ABB2 were clustered into group 1 of zoonotic potential, the genotypes CHB1 and ABB1 were clustered into a new group, and the genotype horse2 was clustered into group 6 of unclear zoonotic potential. In conclusion, this study identified two novel E. bieneusi genotypes in captive Asiatic black bears, and used microsatellite and minisatellite markers to reveal E. bieneusi genetic diversity. Moreover, our findings show that genotypes SC02 (identified in humans) and ABB2 belong to group 1 with zoonotic potential, suggesting the risk of transmission of E. bieneusi from Asiatic black bears to humans and other animals. PMID:28182656

  13. Contrasted Genetic Diversity, Relevance of Climate and Host Plants, and Comments on the Taxonomic Problems of the Genus Picoa (Pyronemataceae, Pezizales)

    PubMed Central

    Sbissi, Imed; Boudabous, Abdellatif; Fortas, Zohra; Moreno, Gabriel; Manjón, José Luis; Gtari, Maher

    2015-01-01

    The species concept within the genus Picoa Vittad. is here revisited in light of new molecular and ecological data obtained from samples collected throughout the Mediterranean basin. Two highly diverse widespread clades and four additional minor lineages were significantly supported by three genes dataset (ITS, 28s LSU and RPB2) inferences for 70 specimens. The two widespread clades occur in very different geographical and ecological areas associated with exclusive host plants in the genus Helianthemum. SEM study of spore surface morphology in these lineages revealed the existence of smooth ascospores in the majority of these clades. However the most frequent lineage in Europe and coastal North Africa displayed either smooth or verrucose spores. Hence this morphological criterion cannot be reliably used to discriminate between the different clades. In addition, SEM observations made on ascospores from several original collections of P. juniperi and P. lefebvrei supported the hypothesis that ornamentation depends on the degree of maturity in some of these lineages. Geographical and ecological, rather than morphological data are here suggested as the most useful characters to separate the different lineages in Picoa. Further studies focusing on these features are needed before the names P. juniperi and P. lefebvrei can be unambiguously linked with the genetic lineages observed. PMID:26390223

  14. Characterization and Genetic Analysis of Rice Mutant crr1 Exhibiting Compromised Non-host Resistance to Puccinia striiformis f. sp. tritici (Pst)

    PubMed Central

    Zhao, Jing; Yang, Yuheng; Yang, Donghe; Cheng, Yulin; Jiao, Min; Zhan, Gangming; Zhang, Hongchang; Wang, Junyi; Zhou, Kai; Huang, Lili; Kang, Zhensheng

    2016-01-01

    Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most devastating diseases of wheat in China. Rapid change to virulence following release of resistant cultivars necessitates ongoing discovery and exploitation of new resistance resources. Considerable effort has been directed at non-host resistance (NHR) which is believed to be durable. In the present study we identified rice mutant crr1 (compromised resistance to rust 1) that exhibited compromised NHR to Pst. Compared with wild type rice variety Nipponbare, crr1 mutant displayed a threefold increase in penetration rate by Pst, and enhanced hyphal growth. The pathogen also developed haustoria in crr1 mesophyll cells, but failed to sporulate. The response to the adapted rice pathogen Magnaporthe oryzae was unchanged in crr1 relative to the wild type. Several defense-related genes involved in the SA- and JA-mediated defense pathways response and in phytoalexin synthesis (such as OsPR1a, OsLOX1, and OsCPS4) were more rapidly and strongly induced in infected crr1 leaves than in the wild type, suggesting that other layers of defense are still in effect. Genetic analysis and mapping located the mutant loci at a region between markers ID14 and RM25792, which cover about 290 kb genome sequence on chromosome 10. Further fine mapping and cloning of the locus should provide further insights into NHR to rust fungi in rice, and may reveal new strategies for improving rust resistance in wheat. PMID:27965705

  15. The Human Skin Double-Stranded DNA Virome: Topographical and Temporal Diversity, Genetic Enrichment, and Dynamic Associations with the Host Microbiome

    PubMed Central

    Hannigan, Geoffrey D.; Meisel, Jacquelyn S.; Tyldsley, Amanda S.; Zheng, Qi; Hodkinson, Brendan P.; SanMiguel, Adam J.; Minot, Samuel; Bushman, Frederic D.

    2015-01-01

    ABSTRACT Viruses make up a major component of the human microbiota but are poorly understood in the skin, our primary barrier to the external environment. Viral communities have the potential to modulate states of cutaneous health and disease. Bacteriophages are known to influence the structure and function of microbial communities through predation and genetic exchange. Human viruses are associated with skin cancers and a multitude of cutaneous manifestations. Despite these important roles, little is known regarding the human skin virome and its interactions with the host microbiome. Here we evaluated the human cutaneous double-stranded DNA virome by metagenomic sequencing of DNA from purified virus-like particles (VLPs). In parallel, we employed metagenomic sequencing of the total skin microbiome to assess covariation and infer interactions with the virome. Samples were collected from 16 subjects at eight body sites over 1 month. In addition to the microenviroment, which is known to partition the bacterial and fungal microbiota, natural skin occlusion was strongly associated with skin virome community composition. Viral contigs were enriched for genes indicative of a temperate phage replication style and also maintained genes encoding potential antibiotic resistance and virulence factors. CRISPR spacers identified in the bacterial DNA sequences provided a record of phage predation and suggest a mechanism to explain spatial partitioning of skin phage communities. Finally, we modeled the structure of bacterial and phage communities together to reveal a complex microbial environment with a Corynebacterium hub. These results reveal the previously underappreciated diversity, encoded functions, and viral-microbial dynamic unique to the human skin virome. PMID:26489866

  16. Discovery of a “White-Gray-Opaque” Tristable Phenotypic Switching System in Candida albicans: Roles of Non-genetic Diversity in Host Adaptation

    PubMed Central

    Guan, Guobo; Dai, Yu; Nobile, Clarissa J.; Liang, Weihong; Cao, Chengjun; Zhang, Qiuyu; Zhong, Jin; Huang, Guanghua

    2014-01-01

    Non-genetic phenotypic variations play a critical role in the adaption to environmental changes in microbial organisms. Candida albicans, a major human fungal pathogen, can switch between several morphological phenotypes. This ability is critical for its commensal lifestyle and for its ability to cause infections. Here, we report the discovery of a novel morphological form in C. albicans, referred to as the “gray” phenotype, which forms a tristable phenotypic switching system with the previously reported white and opaque phenotypes. White, gray, and opaque cell types differ in a number of aspects including cellular and colony appearances, mating competency, secreted aspartyl proteinase (Sap) activities, and virulence. Of the three cell types, gray cells exhibit the highest Sap activity and the highest ability to cause cutaneous infections. The three phenotypes form a tristable phenotypic switching system, which is independent of the regulation of the mating type locus (MTL). Gray cells mate over 1,000 times more efficiently than do white cells, but less efficiently than do opaque cells. We further demonstrate that the master regulator of white-opaque switching, Wor1, is essential for opaque cell formation, but is not required for white-gray transitions. The Efg1 regulator is required for maintenance of the white phenotype, but is not required for gray-opaque transitions. Interestingly, the wor1/wor1 efg1/efg1 double mutant is locked in the gray phenotype, suggesting that Wor1 and Efg1 could function coordinately and play a central role in the regulation of gray cell formation. Global transcriptional analysis indicates that white, gray, and opaque cells exhibit distinct gene expression profiles, which partly explain their differences in causing infections, adaptation ability to diverse host niches, metabolic profiles, and stress responses. Therefore, the white-gray-opaque tristable phenotypic switching system in C. albicans may play a significant role in a wide

  17. The Drosophila melanogaster host model

    PubMed Central

    Igboin, Christina O.; Griffen, Ann L.; Leys, Eugene J.

    2012-01-01

    The deleterious and sometimes fatal outcomes of bacterial infectious diseases are the net result of the interactions between the pathogen and the host, and the genetically tractable fruit fly, Drosophila melanogaster, has emerged as a valuable tool for modeling the pathogen–host interactions of a wide variety of bacteria. These studies have revealed that there is a remarkable conservation of bacterial pathogenesis and host defence mechanisms between higher host organisms and Drosophila. This review presents an in-depth discussion of the Drosophila immune response, the Drosophila killing model, and the use of the model to examine bacterial–host interactions. The recent introduction of the Drosophila model into the oral microbiology field is discussed, specifically the use of the model to examine Porphyromonas gingivalis–host interactions, and finally the potential uses of this powerful model system to further elucidate oral bacterial-host interactions are addressed. PMID:22368770

  18. Genetically modified bacterial strains and novel bacterial artificial chromosome shuttle vectors for constructing environmental libraries and detecting heterologous natural products in multiple expression hosts.

    PubMed

    Martinez, Asuncion; Kolvek, Steven J; Yip, Choi Lai Tiong; Hopke, Joern; Brown, Kara A; MacNeil, Ian A; Osburne, Marcia S

    2004-04-01

    The enormous diversity of uncultured microorganisms in soil and other environments provides a potentially rich source of novel natural products, which is critically important for drug discovery efforts. Our investigators reported previously on the creation and screening of an Escherichia coli library containing soil DNA cloned and expressed in a bacterial artificial chromosome (BAC) vector. In that initial study, our group identified novel enzyme activities and a family of antibacterial small molecules encoded by soil DNA cloned and expressed in E. coli. To continue our pilot study of the utility and feasibility of this approach to natural product drug discovery, we have expanded our technology to include Streptomyces lividans and Pseudomonas putida as additional hosts with different expression capabilities, and herein we describe the tools we developed for transferring environmental libraries into all three expression hosts and screening for novel activities. These tools include derivatives of S. lividans that contain complete and unmarked deletions of the act and red endogenous pigment gene clusters, a derivative of P. putida that can accept environmental DNA vectors and integrate the heterologous DNA into the chromosome, and new BAC shuttle vectors for transferring large fragments of environmental DNA from E. coli to both S. lividans and P. putida by high-throughput conjugation. Finally, we used these tools to confirm that the three hosts have different expression capabilities for some known gene clusters.

  19. Rapidly expanding genetic diversity and host range of the Circoviridae viral family and other Rep encoding small circular ssDNA genomes

    PubMed Central

    Delwart, Eric; Li, Linlin

    2011-01-01

    The genomes of numerous circoviruses and distantly related circular DNA viruses encoding a rolling circle replication initiator protein (Rep) have been characterized from the tissues of mammals, fish, insects, and plants (geminivirus and nanovirus), human and animal feces, in an algae cell, and in diverse environmental samples. We review the genome organization, phylogenetic relationships and initial prevalence studies of cycloviruses, a proposed new genus in the Circoviridae family. Viral fossil rep sequences were also identified integrated on the chromosomes of mammals, frogs, lancelets, crustaceans, mites, gastropods, roundworms, placozoans, hydrozoans, protozoans, land plants, fungi, algae, and phytoplasma bacterias and their plasmids, reflecting their past host range. An ancient origin for viruses with rep-encoding single stranded small circular genomes, predating the diversification of eukaryotes, is discussed. The cellular hosts and pathogenicity of many recently described rep-containing circular genomes remain to be determined. Future studies of the virome of single cell and multi-cellular eukaryotes are likely to further extend the known diversity and host-range of small rep-containing circular viral genomes. PMID:22155583

  20. Evaluation of genetic diversity and host resistance to stem rust in durum wheat accessions from the USDA National Small Grains Collection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The USDA-ARS National Small Grains Collection (NSGC) located in Aberdeen, ID, maintains collections representing the global diversity of small grains and their wild relatives. To evaluate the utility of the NSGC durum wheat accessions, we assessed genetic diversity and LD patterns in a durum core s...

  1. Tourmaline occurrences within the Penamacor-Monsanto granitic pluton and host-rocks (Central Portugal): genetic implications of crystal-chemical and isotopic features

    NASA Astrophysics Data System (ADS)

    da Costa, I. Ribeiro; Mourão, C.; Récio, C.; Guimarães, F.; Antunes, I. M.; Ramos, J. Farinha; Barriga, F. J. A. S.; Palmer, M. R.; Milton, J. A.

    2014-04-01

    Tourmalinization associated with peraluminous granitic intrusions in metapelitic host-rocks has been widely recorded in the Iberian Peninsula, given the importance of tourmaline as a tracer of granite magma evolution and potential indicator of Sn-W mineralizations. In the Penamacor-Monsanto granite pluton (Central Eastern Portugal, Central Iberian Zone), tourmaline occurs: (1) as accessory phase in two-mica granitic rocks, muscovite-granites and aplites, (2) in quartz (±mica)-tourmaline rocks (tourmalinites) in several exocontact locations, and (3) as a rare detrital phase in contact zone hornfels and metapelitic host-rocks. Electron microprobe and stable isotope (δ18O, δD, δ11B) data provide clear distinctions between tourmaline populations from these different settings: (a) schorl-oxyschorl tourmalines from granitic rocks have variable foititic component (X□ = 17-57 %) and Mg/(Mg + Fe) ratios (0.19-0.50 in two-mica granitic rocks, and 0.05-0.19 in the more differentiated muscovite-granite and aplites); granitic tourmalines have constant δ18O values (12.1 ± 0.1 ‰), with wider-ranging δD (-78.2 ± 4.7 ‰) and δ11B (-10.7 to -9.0 ‰) values; (b) vein/breccia oxyschorl [Mg/(Mg + Fe) = 0.31-0.44] results from late, B- and Fe-enriched magma-derived fluids and is characterized by δ18O = 12.4 ‰, δD = -29.5 ‰, and δ11B = -9.3 ‰, while replacement tourmalines have more dravitic compositions [Mg/(Mg + Fe) = 0.26-0.64], close to that of detrital tourmaline in the surrounding metapelitic rocks, and yield relatively constant δ18O values (13.1-13.3 ‰), though wider-ranging δD (-58.5 to -36.5 ‰) and δ11B (-10.2 to -8.8 ‰) values; and (c) detrital tourmaline in contact rocks and regional host metasediments is mainly dravite [Mg/(Mg + Fe) = 0.35-0.78] and oxydravite [Mg/(Mg + Fe) = 0.51-0.58], respectively. Boron contents of the granitic rocks are low (<650 ppm) compared to the minimum B contents normally required for tourmaline saturation in

  2. Tracing early stages of species differentiation: Ecological, morphological and genetic divergence of Galápagos sea lion populations

    PubMed Central

    2008-01-01

    Background Oceans are high gene flow environments that are traditionally believed to hamper the build-up of genetic divergence. Despite this, divergence appears to occur occasionally at surprisingly small scales. The Galápagos archipelago provides an ideal opportunity to examine the evolutionary processes of local divergence in an isolated marine environment. Galápagos sea lions (Zalophus wollebaeki) are top predators in this unique setting and have an essentially unlimited dispersal capacity across the entire species range. In theory, this should oppose any genetic differentiation. Results We find significant ecological, morphological and genetic divergence between the western colonies and colonies from the central region of the archipelago that are exposed to different ecological conditions. Stable isotope analyses indicate that western animals use different food sources than those from the central area. This is likely due to niche partitioning with the second Galápagos eared seal species, the Galápagos fur seal (Arctocephalus galapagoensis) that exclusively dwells in the west. Stable isotope patterns correlate with significant differences in foraging-related skull morphology. Analyses of mitochondrial sequences as well as microsatellites reveal signs of initial genetic differentiation. Conclusion Our results suggest a key role of intra- as well as inter-specific niche segregation in the evolution of genetic structure among populations of a highly mobile species under conditions of free movement. Given the monophyletic arrival of the sea lions on the archipelago, our study challenges the view that geographical barriers are strictly needed for the build-up of genetic divergence. The study further raises the interesting prospect that in social, colonially breeding mammals additional forces, such as social structure or feeding traditions, might bear on the genetic partitioning of populations. PMID:18485220

  3. Host range and genetic diversity of croton yellow vein mosaic virus, a weed-infecting monopartite begomovirus causing leaf curl disease in tomato.

    PubMed

    Pramesh, D; Mandal, Bikash; Phaneendra, Chigurupati; Muniyappa, V

    2013-03-01

    Croton yellow vein mosaic virus (CYVMV) is a widely occurring begomovirus in Croton bonplandianum, a common weed in the Indian subcontinent. In this study, CYVMV (genus Begomovirus, family Geminiviridae) was transmitted by whiteflies (Bemisia tabaci) to as many as 35 plant species belonging to 11 families, including many vegetables, tobacco varieties, ornamentals and weeds. CYVMV produced bright yellow vein symptoms in croton, whereas in all the other host species, the virus produced leaf curl symptoms. CYVMV produced leaf curl in 13 tobacco species and 22 cultivars of Nicotiana tabacum and resembled tobacco leaf curl virus (TobLCV) in host reactions. However, CYVMV was distinguished from TobLCV in four differential hosts, Ageratum conyzoides, C. bonplandianum, Euphorbia geniculata and Sonchus bracyotis. The complete genome sequences of four isolates originating from northern, eastern and southern India revealed that a single species of DNA-A and a betasatellite, croton yellow vein mosaic betasatellite (CroYVMB) were associated with the yellow vein mosaic disease of croton. The sequence identity among the isolates of CYVMV DNA-A and CroYVMB occurring in diverse plant species was 91.8-97.9 % and 83.3-100 %, respectively. The CYVMV DNA-A and CroYVMB generated through rolling-circle amplification of the cloned DNAs produced typical symptoms of yellow vein mosaic and leaf curling in croton and tomato, respectively. The progeny virus from both the croton and tomato plants was transmitted successfully by B. tabaci. The present study establishes the etiology of yellow vein mosaic disease of C. bonplandianum and provides molecular evidence that a weed-infecting monopartite begomovirus causes leaf curl in tomato.

  4. A genetically distinct Schistosoma from Radix luteola from Nepal related to Schistosoma turkestanicum: A phylogenetic study of schistosome and snail host.

    PubMed

    Devkota, Ramesh; Brant, Sara V; Loker, Eric S

    2016-12-01

    During a survey of freshwater snails in the Terai region of southern Nepal, 16 of 2588 specimens of Radix luteola from 4 different habitats were found to be shedding schistosome cercariae. None of the 1411 specimens of Radix acuminata we collected were positive for schistosomes. Analysis of 28S, cox1, 16S and 12S sequences indicated that all the R. luteola-derived schistosomes were genetically very similar to one another and, although unambiguously grouping most closely to the widespread Asian species Schistosoma turkestanicum, were clearly genetically distinct from it. We lack information from other life cycle stages to verify the specific identity of these cercariae, but it is possible they are of Schistosoma bomfordi or Schistosoma dattai, both species previously known only from northern India, the latter species known to infect R. luteola. This study provides sequence evidence for a third genetically distinct lymnaeid-transmitted Schistosoma lineage in Asia (to go along with S. turkestanicum and S. incognitum). As a close relative of S. turkestanicum, it provides the first direct molecular evidence to accompany morphological results from earlier studies for the presence of a S. turkestanicum species group in Asia. It increases to five the number of known or suspected mammalian schistosome species to be present in the Terai region of Nepal. Radix luteola and R. acuminata were identified and differentiated using conchological features and by molecular phylogenetic analyses of cox1 and 16S genes.

  5. Genetic characterisation of Fasciola samples from different host species and geographical localities revealed the existence of F. hepatica and F. gigantica in Niger.

    PubMed

    Ali, H; Ai, L; Song, H Q; Ali, S; Lin, R Q; Seyni, B; Issa, G; Zhu, X Q

    2008-04-01

    In the present study, 16 samples representing Fasciola (Platyhelminthes: Trematoda: Digenea) from sheep and cattle from seven geographical locations in Niger were characterized genetically by sequences of the first (ITS-1) and second (ITS-2) internal transcribed spacers (ITS) of nuclear ribosomal DNA (rDNA). The ITS rDNA was amplified from individual liver flukes by polymerase chain reaction (PCR), and the amplicons were sequenced directly. The lengths of the ITS-1 and ITS-2 sequences were 422 and 361/362 bp, respectively, for all liver fluke samples sequenced. Comparison of the ITS sequences of the Niger Fasciola samples examined in the present study with that of Fasciola hepatica, Fasciola gigantica, and the "intermediate Fasciola" from elsewhere revealed that the Niger Fasciola samples examined represent two species, namely F. hepatica and F. gigantica. This is the first demonstration of the existence of both F. hepatica and F. gigantica in Niger by a genetic approach, which provides foundation for further studies on F. hepatica and F. gigantica in Niger and has implications for studying the population genetic structure of the Niger Fasciola and for the diagnosis and control of the disease they cause.

  6. Genetic Complexity of the Human Innate Host Defense Molecules, Surfactant Protein A1 (SP-A1) and SP-A2—Impact on Function

    PubMed Central

    Floros, Joanna; Wang, Guirong; Mikerov, Anatoly N.

    2010-01-01

    Innate immunity mechanisms play a critical role in the primary response to invading pathogenic microorganisms and other insulting agents. The innate lung immune system includes lung surfactant, a lipoprotein complex that carries out a function essential for life, that is, reduction of the surface tension at the air–liquid interphase of the alveolar space. By means of this function, pulmonary surfactant prevents lung collapse, therefore ensuring normal lung function and lung health. Pulmonary surfactant contains a number of host-defense molecules that are involved in the elimination of pathogens, viruses, particles, allergens, and other insults, as well as in the control of inflammation. This review is concerned with one of the surfactant proteins, the human (h) surfactant protein A (hSP-A), which, in addition to its role in surfactant-related functions, plays an important role in the modulation of lung host defense. The hSP-A locus has been identified with extensive complexity that may have an impact on its function, structure, and regulation. In humans, two genes—SP-A1 (SFTPA1) and SP-A2 (SFTPA2)—encode SP-A, with SP-A2 gene products being more biologically active than SP-A1 in most of the in vitro assays investigated. Although the two hSP-A genes share a high level of sequence similarity, differences in the structure and function between SP-A1 and SP-A2 have been observed in recent studies. In this review, we discuss the human SP-A complexity and how this may affect SP-A function. PMID:19392648

  7. The role of symbiont genetic distance and potential adaptability in host preference towards Pseudonocardia symbionts in Acromyrmex leaf-cutting ants.

    PubMed

    Poulsen, Michael; Maynard, Janielle; Roland, Damien L; Currie, Cameron R

    2011-01-01

    Fungus-growing ants display symbiont preference in behavioral assays, both towards the fungus they cultivate for food and Actinobacteria they maintain on their cuticle for antibiotic production against parasites. These Actinobacteria, genus Pseudonocardia Henssen (Pseudonocardiacea: Actinomycetales), help defend the ants' fungal mutualist from specialized parasites. In Acromyrmex Mayr (Hymenoptera: Formicidae) leaf-cutting ants, individual colonies maintain either a single or a few strains of Pseudonocardia, and the symbiont is primarily vertically transmitted between generations by colony-founding queens. A recent report found that Acromyrmex workers are able to differentiate between their native Pseudonocardia strain and non-native strains isolated from sympatric or allopatric Acromyrmex species, and show preference for their native strain. Here we explore worker preference when presented with two non-native strains, elucidating the role of genetic distance on preference between strains and Pseudonocardia origin. Our findings suggest that ants tend to prefer bacteria more closely related to their native bacterium and that genetic similarity is probably more important than whether symbionts are ant-associated or free-living. Preliminary findings suggest that when continued exposure to a novel Pseudonocardia strain occurs, ant symbiont preference is potentially adaptable, with colonies apparently being able to alter symbiont preference over time. These findings are discussed in relation to the role of adaptive recognition, potential ecological flexibility in symbiont preference, and more broadly, in relation to self versus non-self recognition.

  8. First genomic analysis of the broad-host-range Rhizobium sp. LPU83 strain, a member of the low-genetic diversity Oregon-like Rhizobium sp. group.

    PubMed

    Tejerizo, Gonzalo Torres; Del Papa, María Florencia; Draghi, Walter; Lozano, Mauricio; Giusti, María de Los Ángeles; Martini, Carla; Salas, María Eugenia; Salto, Ileana; Wibberg, Daniel; Szczepanowski, Rafael; Weidner, Stefan; Schlüter, Andreas; Lagares, Antonio; Pistorio, Mariano

    2011-08-20

    Alfalfa (Medicago sativa) is the most cultivated forage legume for cattle and animal feeding, occupying about 32 million hectares over the world. Management of the N₂-fixing symbiosis of this plant to maximize crop production is therefore an important objective. A fundamental constraint to this aim emerges when a moderately low soil pH hampers the establishment of an effective symbiosis with indigenous and/or inoculated rhizobia. Besides the association of alfalfa with Ensifer (Sinorhizobium) meliloti, this legume is able to establish a symbiosis with Ensifer (Sinorhizobium) medicae and with less characterized types of rhizobia, such as the Oregon-like strains, Rhizobium sp. Or191 initially isolated in the USA, and the Rhizobium sp. LPU83 strain, from Argentina. These strains are acid-tolerant, highly competitive for acidic-soil-alfalfa nodulation, but inefficient for biological nitrogen fixation with alfalfa. These features position the Oregon-like rhizobia as strains of potential risk in agricultural soils compared with the efficient symbiont E. meliloti. Moreover, the collected genetic information has revealed that the genomic structure of these rhizobial isolates is complex in terms of sequence similarities shared with other rhizobia. Such a "patched" genetic composition has obviously imposed severe restrictions to the classical taxonomy of these rhizobia. In this work we summarize the accumulated knowledge about the Oregon-like rhizobia and present a phylogenetic analysis based on genome sequence data of Rhizobium sp. LPU83 obtained by a high-throughput sequencing on the Genome Sequencer FLX Titanium platform. The accessibility of the complete genomic sequence will release up more experimental possibilities since this information will then enable biochemical studies as well as proteomics and transcriptomics approaches.

  9. Phages of lactic acid bacteria: The role of genetics in understanding phage-host interactions and their co-evolutionary processes

    SciTech Connect

    Mahony, Jennifer; Ainsworth, Stuart; Stockdale, Stephen; Sinderen, Douwe van

    2012-12-20

    Dairy fermentations are among the oldest food processing applications, aimed at preservation and shelf-life extension through the use of lactic acid bacteria (LAB) starter cultures, in particular strains of Lactococcus lactis, Streptococcus thermophilus, Lactobacillus spp. and Leuconostoc spp. Traditionally this was performed by continuous passaging of undefined cultures from a finished fermentation to initiate the next fermentation. More recently, consumer demands on consistent and desired flavours and textures of dairy products have led to a more defined approach to such processes. Dairy (starter) companies have responded to the need to define the nature and complexity of the starter culture mixes, and dairy fermentations are now frequently based on defined starter cultures of low complexity, where each starter component imparts specific technological properties that are desirable to the product. Both mixed and defined starter culture approaches create the perfect environment for the proliferation of (bacterio)phages capable of infecting these LAB. The repeated use of the same starter cultures in a single plant, coupled to the drive towards higher and consistent production levels, increases the risk and negative impact of phage infection. In this review we will discuss recent advances in tracking the adaptation of phages to the dairy industry, the advances in understanding LAB phage-host interactions, including evolutionary and genomic aspects.

  10. Construction and analysis of regulatory genetic networks in cervical cancer based on involved microRNAs, target genes, transcription factors and host genes

    PubMed Central

    WANG, NING; XU, ZHIWEN; WANG, KUNHAO; ZHU, MINGHUI; LI, YANG

    2014-01-01

    Over recent years, genes and microRNA (miRNA/miR) have been considered as key biological factors in human carcinogenesis. During cancer development, genes may act as multiple identities, including target genes of miRNA, transcription factors and host genes. The present study concentrated on the regulatory networks consisting of the biological factors involved in cervical cancer in order to investigate their features and affect on this specific pathology. Numerous raw data was collected and organized into purposeful structures, and adaptive procedures were defined for application to the prepared data. The networks were therefore built with the factors as basic components according to their interacting associations. The networks were constructed at three levels of interdependency, including a differentially-expressed network, a related network and a global network. Comparisons and analyses were made at a systematic level rather than from an isolated gene or miRNA. Critical hubs were extracted in the core networks and notable features were discussed, including self-adaption feedback regulation. The present study expounds the pathogenesis from a novel point of view and is proposed to provide inspiration for further investigation and therapy. PMID:24944708

  11. Genetics of incipient speciation in Drosophila mojavensis: II. Host plants and mating status influence cuticular hydrocarbon QTL expression and G x E interactions.

    PubMed

    Etges, William J; de Oliveira, Cassia Cardoso; Ritchie, Michael G; Noor, Mohamed A F

    2009-07-01

    We performed a quantitative trait locus (QTL) analysis of epicuticular hydrocarbon variation in 1650 F(2) males from crosses of Baja California and mainland Mexico populations of Drosophila mojavensis cultured on two major host cacti. Principal component (PC) analysis revealed five PCs that accounted for 82% of the total epicuticular hydrocarbon variation. Courtship trials with mainland females were used to characterize hydrocarbon profiles of mated and unmated F(2) males, and logistic regression analysis showed that cactus substrates, two PCs, and a PC by cactus interaction were associated with mating success. Multiple QTLs were detected for each hydrocarbon PC and seven G x E (cactus) interactions were uncovered for the X, second, and fourth chromosomes. Males from the courtship trials and virgins were used, so "exposure to females" was included as a factor in QTL analyses. "Exposed" males expressed significantly different hydrocarbon profiles than virgins for most QTLs, particularly for the two PCs associated with mating success. Ten QTLs showed G x E (exposure) interactions with most resulting from mainland genotypes expressing altered hydrocarbon amounts when exposed to females compared to Baja genotypes. Many cactus x exposure interaction terms detected across QTL and all PCs confirmed that organ pipe-reared males expressed significantly lower hydrocarbon amounts when exposed to females than when reared on agria cactus. Epicuticular hydrocarbon variation in D. mojavensis is therefore a multigenic trait with some epistasis, multiple QTLs exhibited pleiotropy, correlated groups of hydrocarbons and cactus substrates determined courtship success, and males altered their hydrocarbon profiles in response to females.

  12. Phenylketonuria Genetic Screening Simulation

    ERIC Educational Resources Information Center

    Erickson, Patti

    2012-01-01

    After agreeing to host over 200 students on a daylong genetics field trip, the author needed an easy-to-prepare genetics experiment to accompany the DNA-necklace and gel-electrophoresis activities already planned. One of the student's mothers is a pediatric physician at the local hospital, and she suggested exploring genetic-disease screening…

  13. Variation in Host and Pathogen in the Neonectria/Malus Interaction; toward an Understanding of the Genetic Basis of Resistance to European Canker

    PubMed Central

    Gómez-Cortecero, Antonio; Saville, Robert J.; Scheper, Reiny W. A.; Bowen, Joanna K.; Agripino De Medeiros, Hugo; Kingsnorth, Jennifer; Xu, Xiangming; Harrison, Richard J.

    2016-01-01

    Apple canker caused by the phytopathogenic fungus Neonectria ditissima is an economically important disease, which has spread in recent years to almost all pome-producing regions of the world. N. ditissima is able to cross-infect a wide range of apple varieties and causes branch and trunk lesions, known as cankers. Most modern apple varieties are susceptible and in extreme cases suffer from high mortality (up to 50%) in the early phase of orchard establishment. There is no known race structure of the pathogen and the global level of genetic diversity of the pathogen population is unknown. Resistance breeding is underway in many global breeding programmes, but nevertheless, a total resistance to canker has not yet been demonstrated. Here we present preliminary data from a survey of the phylogenetic relationships between global isolates of N. ditissima which reveals only slight evidence for population structure. In addition we report the results of four rapid screening tests to assess the response to N. ditissima in different apple scion and rootstock varieties, which reveals abundant variation in resistance responses in both cultivar and rootstock material. Further seedling tests show that the segregation patterns of resistance and susceptibility vary widely between crosses. We discuss inconsistencies in test performance with field observations and discuss future research opportunities in this area. PMID:27695463

  14. Chlamydia pneumoniae Is Genetically Diverse in Animals and Appears to Have Crossed the Host Barrier to Humans on (At Least) Two Occasions

    PubMed Central

    Mitchell, Candice M.; Hutton, Susan; Myers, Garry S. A.; Brunham, Robert; Timms, Peter

    2010-01-01

    Chlamydia pneumoniae is a common human and animal pathogen associated with a wide range of diseases. Since the first isolation of C. pneumoniae TWAR in 1965, all human isolates have been essentially clonal, providing little evolutionary insight. To address this gap, we investigated the genetic diversity of 30 isolates from diverse geographical locations, from both human and animal origin (amphibian, reptilian, equine and marsupial). Based on the level of variation that we observed at 23 discreet gene loci, it was clearly evident that the animal isolates were more diverse than the isolates of human origin. Furthermore, we show that C. pneumoniae isolates could be grouped into five major genotypes, A-E, with A, B, D and E genotypes linked by geographical location, whereas genotype C was found across multiple continents. Our evidence strongly supports two separate animal-to-human cross species transfer events in the evolutionary history of this pathogen. The C. pneumoniae human genotype identified in the USA, Canada, Taiwan, Iran, Japan, Korea and Australia (non-Indigenous) most likely originated from a single amphibian or reptilian lineage, which appears to have been previously geographically widespread. We identified a separate human lineage present in two Australian Indigenous isolates (independent geographical locations). This lineage is distinct and is present in Australian amphibians as well as a range of Australian marsupials. PMID:20502684

  15. Genetic variation in Surfactant Protein-A2 (SP-A2) leads to differential binding to Mycoplasma pneumoniae membranes and regulation of host responses

    PubMed Central

    Ledford, Julie G.; Voelker, Dennis R.; Addison, Kenneth J.; Wang, Ying; Nikam, Vinayak; Degan, Simone; Kandasamy, Pitachaimani; Tanyaratsrisakul, Sasipa; Fischer, Bernard M.; Kraft, Monica; Hollingsworth, John W.

    2015-01-01

    Mycoplasma pneumoniae (Mp) is an extracellular pathogen that colonizes mucosal surfaces of the respiratory tract and is associated with asthma exacerbations. Previous reports demonstrate that surfactant protein-A (SP-A) binds live Mp and mycoplasma membranes (MMF) with high affinity. Humans express a repertoire of single amino acid genetic variants of SP-A that may be associated with lung disease, and our findings demonstrate that allelic differences in SP-A2 (Gln223Lys) affect the binding to MMF. We show that SP-A−/− mice are more susceptible to MMF exposure and have significant increases in mucin production and neutrophil recruitment. Novel humanized-SP-A2 transgenic mice harboring the hSP-A2 223K allele exhibit reduced neutrophil influx and mucin production in the lungs, when challenged with MMF, compared to SP-A−/− mice. Conversely, mice expressing hSP-A2 223Q have increased neutrophil influx and mucin production that is similar to SP-A−/− mice. Using tracheal epithelial cell cultures, we show that enhanced mucin production to MMF occurs in the absence of SP-A, and is not dependent upon neutrophil recruitment. Increased phosphorylation of the epidermal growth factor receptor (EGFR) was evident in the lungs of MMF-challenged mice when SP-A was absent. Pharmacologic inhibition of EGFR prior to MMF challenge dramatically reduced mucin production in SP-A−/− mice. These findings suggest a protective role for SP-A in limiting MMF-stimulated mucin production that occurs through interference with EGFR mediated signaling. The SP-A interaction with the EGFR signaling pathway appears to occur in an allele specific manner that may have important implications for SP-A polymorphisms in human diseases. PMID:25957169

  16. Mycobacterium tuberculosis and the host response

    PubMed Central

    Kaufmann, Stefan H.E.; Cole, Stewart T.; Mizrahi, Valerie; Rubin, Eric; Nathan, Carl

    2005-01-01

    Mycobacterium tuberculosis remains a leading cause of morbidity and mortality worldwide. Advances reported at a recent international meeting highlight insights and controversies in the genetics of M. tuberculosis and the infected host, the nature of protective immune responses, adaptation of the bacillus to host-imposed stresses, animal models, and new techniques. PMID:15939785

  17. Host genetic resistance to Marek's disease sustains protective efficacy of herpesvirus of turkey in both experimental and commercial lines of chickens.

    PubMed

    Chang, Shuang; Xie, Qingmei; Dunn, John R; Ernst, Catherine W; Song, Jiuzhou; Zhang, Huanmin

    2014-04-01

    Marek's disease (MD) remains a continual threat to the poultry industry worldwide as the MD virus continues evolving in virulence. MD has been controlled primarily by intensive use of vaccines since 1969. Based on the antigenic and pathogenic differences of the viruses that the vaccines were derived from, commercially available MD vaccines are classified into three categories, MDV-1, -2, and -3 vaccines. This study was designed to compare the protective efficacy of MDV-1 (CVI988/Rispens) and MDV-3 (HVT) vaccines against challenge of a very virulent plus strain of Marek's disease virus (vv+MDV) in experimental and commercial egg-layer lines of chickens under controlled experimental conditions. The two experimental lines (63 and 72) of chickens carry a uniform MHC B*2 haplotype and are known to differ in resistance to MD. One of the two commercial egg-layer lines (WL and BL) segregates for three MHC haplotypes (B*2, B*15, and B*21); the other is unclear. MD incidences of the unvaccinated groups of both experimental lines and both commercial lines were 100% or close to 100% induced by the vv+MDV, 648A. Survived day patterns of the unvaccinated groups significantly differed between the two experimental lines, but did not between the two commercial lines, which suggested the two experimental lines do differ in resistance to MD but not between the two commercial lines. At manufacturers' recommended vaccine dosage, two HVTs conveyed comparable protection for the MD resistant line 63 chickens as did both CVI988/Rispens used in this study. The two HVTs also conveyed comparable protection for both commercial lines of chickens as did one of two CVI988/Rispens (CVI988/Rispens-A). At a 2000PFU uniform dose, HVT and CVI988/Rispens again conveyed comparable protection for the MD resistant experimental line of chickens. The findings suggest vaccine protective efficacy is modulated by factors including the types and the sources of vaccines and the genetic backgrounds of chickens

  18. Can host ecology and kin selection predict parasite virulence?

    PubMed

    Gleichsner, Alyssa M; Minchella, Dennis J

    2014-07-01

    Parasite virulence, or the damage a parasite does to its host, is measured in terms of both host costs (reductions in host growth, reproduction and survival) and parasite benefits (increased transmission and parasite numbers) in the literature. Much work has shown that ecological and genetic factors can be strong selective forces in virulence evolution. This review uses kin selection theory to explore how variations in host ecological parameters impact the genetic relatedness of parasite populations and thus virulence. We provide a broad overview of virulence and population genetics studies and then draw connections to existing knowledge about natural parasite populations. The impact of host movement (transporting parasites) and host resistance (filtering parasites) on the genetic structure and virulence of parasite populations is explored, and empirical studies of these factors using Plasmodium and trematode systems are proposed.

  19. Hosts and parasites as aliens.

    PubMed

    Taraschewski, H

    2006-06-01

    Over the past decades, various free-living animals (hosts) and their parasites have invaded recipient areas in which they had not previously occurred, thus gaining the status of aliens or exotics. In general this happened to a low extent for hundreds of years. With variable frequency, invasions have been followed by the dispersal and establishment of non-indigenous species, whether host or parasite. In the literature thus far, colonizations by both hosts and parasites have not been treated and reviewed together, although both are usually interwoven in various ways. As to those factors permitting invasive success and colonization strength, various hypotheses have been put forward depending on the scientific background of respective authors and on the conspicuousness of certain invasions. Researchers who have tried to analyse characteristic developmental patterns, the speed of dispersal or the degree of genetic divergence in populations of alien species have come to different conclusions. Among parasitologists, the applied aspects of parasite invasions, such as the negative effects on economically important hosts, have long been at the centre of interest. In this contribution, invasions by hosts as well as parasites are considered comparatively, revealing many similarities and a few differences. Two helminths, the liver fluke, Fasciola hepatica, of cattle and sheep and the swimbladder nematode, Anguillicola crassus, of eels are shown to be useful as model parasites for the study of animal invasions and environmental global change. Introductions of F. hepatica have been associated with imports of cattle or other grazing animals. In various target areas, susceptible lymnaeid snails serving as intermediate hosts were either naturally present and/or were introduced from the donor continent of the parasite (Europe) and/or from other regions which were not within the original range of the parasite, partly reflecting progressive stages of a global biota change. In several

  20. Ability of a Generalist Seed Beetle to Colonize an Exotic Host: Effects of Host Plant Origin and Oviposition Host.

    PubMed

    Amarillo-Suárez, A; Repizo, A; Robles, J; Diaz, J; Bustamante, S

    2017-02-02

    The colonization of an exotic species by native herbivores is more likely to occur if that herbivore is a generalist. There is little information on the life-history mechanisms used by native generalist insects to colonize exotic hosts and how these mechanisms are affected by host properties. We examined the ability of the generalist seed beetle Stator limbatus Horn to colonize an exotic species. We compared its host preference, acceptability, performance, and egg size when ovipositing and developing on two native (Pithecellobium dulce (Roxb.) Benth and Senegalia riparia (Kunth)) and one exotic legume species (Leucaena leucocephala (Lam.)). We also analyzed the seed chemistry. We found that females recognize the exotic species as an unfavorable host for larval development and that they delayed oviposition and laid fewer and larger eggs on the exotic species than on the native species. Survivorship on the exotic host was 0%. Additionally, seeds of the native species contain five chemical compounds that are absent in the exotic species, and the exotic species contains three sterols, which are absent in the native legumes. Genetically based differences between beetles adapted to different hosts, plastic responses toward new hosts, and chemical differences among seeds are important in host colonization and recognition of the exotic host. In conclusion, the generalist nature of S. limbatus does not influence its ability to colonize L. leucocephala. Explanations for the colonization of exotic hosts by generalist native species and for the success of invasive species must be complemented with studies measuring local adaptation and plasticity.

  1. Understanding Host-Switching by Ecological Fitting

    PubMed Central

    Araujo, Sabrina B. L.; Braga, Mariana Pires; Brooks, Daniel R.; Agosta, Salvatore J.; Hoberg, Eric P.; von Hartenthal, Francisco W.; Boeger, Walter A.

    2015-01-01

    Despite the fact that parasites are highly specialized with respect to their hosts, empirical evidence demonstrates that host switching rather than co-speciation is the dominant factor influencing the diversification of host-parasite associations. Ecological fitting in sloppy fitness space has been proposed as a mechanism allowing ecological specialists to host-switch readily. That proposal is tested herein using an individual-based model of host switching. The model considers a parasite species exposed to multiple host resources. Through time host range expansion can occur readily without the prior evolution of novel genetic capacities. It also produces non-linear variation in the size of the fitness space. The capacity for host colonization is strongly influenced by propagule pressure early in the process and by the size of the fitness space later. The simulations suggest that co-adaptation may be initiated by the temporary loss of less fit phenotypes. Further, parasites can persist for extended periods in sub-optimal hosts, and thus may colonize distantly related hosts by a "stepping-stone" process. PMID:26431199

  2. Two genetically related begomoviruses causing tomato leaf curl disease in Togo and Nigeria differ in virulence and host range but do not require a betasatellite for induction of disease symptoms.

    PubMed

    Kon, Tatsuya; Gilbertson, Robert L

    2012-01-01

    Tomato leaf curl disease (ToLCD) has emerged as a major constraint on tomato production in some parts of West Africa. In this study, begomoviruses associated with ToLCD in Togo and Nigeria were characterized, as well as a betasatellite associated with the disease in Togo. The genome organization of both viruses is typical of Old World monopartite begomoviruses. Sequence analysis revealed that the begomovirus from Togo is a variant of tomato leaf curl Kumasi virus (ToLCKuV) from Ghana, and it is designated ToLCKuV-[Togo:Pagouda:2006] (ToLCKuV-[TG:Pag:06]). The begomovirus from Nigeria has a recombinant genome, composed of sequences of ToLCKuV (major parent) and a cotton leaf curl Gezira virus (CLCuGV)-like virus, and possesses an unusual non-reiterated replication-associated protein (Rep) binding site. Moreover, because the sequence has <89% identity with those of previously characterized begomoviruses, it is a new species and is designated tomato leaf curl Nigeria virus-[Nigeria:Odogbo:2006] (ToLCNGV-[NG:Odo:06]). The cloned DNAs of ToLCKuV-TG and ToLCNGV were infectious and induced leaf curl symptoms in tomato plants, but ToLCNGV was comparatively more virulent. Both viruses also induced stunted growth and leaf curl symptoms in other solanaceous species (various Nicotiana spp. and Datura stramonium), whereas ToLCNGV but not ToLCKuV-TG induced symptoms in common bean plants. The betasatellite associated with ToLCD in Togo is genetically distinct (i.e., <78% nucleotide sequence identity with previously identified betasatellites) and is designated tomato leaf curl Togo betasatellite-[Togo:Pagouda:2006] (ToLCTGB-[TG:Pag:06]). Replication and systemic spread of ToLCTGB in tomato was mediated by ToLCKuV-TG and ToLCNGV; however, the betasatellite had no effect on disease symptoms induced by either begomovirus. In contrast, ToLCTGB increased symptom severity induced by both viruses in Nicotiana spp. and D. stramonium. Thus, although ToLCTGB increased symptom severity in a

  3. Host plant adaptation in Drosophila mettleri populations.

    PubMed

    Castrezana, Sergio; Bono, Jeremy M

    2012-01-01

    The process of local adaptation creates diversity among allopatric populations, and may eventually lead to speciation. Plant-feeding insect populations that specialize on different host species provide an excellent opportunity to evaluate the causes of ecological specialization and the subsequent consequences for diversity. In this study, we used geographically separated Drosophila mettleri populations that specialize on different host cacti to examine oviposition preference for and larval performance on an array of natural and non-natural hosts (eight total). We found evidence of local adaptation in performance on saguaro cactus (Carnegiea gigantea) for populations that are typically associated with this host, and to chemically divergent prickly pear species (Opuntia spp.) in a genetically isolated population on Santa Catalina Island. Moreover, each population exhibited reduced performance on the alternative host. This finding is consistent with trade-offs associated with adaptation to these chemically divergent hosts, although we also discuss alternative explanations for this pattern. For oviposition preference, Santa Catalina Island flies were more likely to oviposit on some prickly pear species, but all populations readily laid eggs on saguaro. Experiments with non-natural hosts suggest that factors such as ecological opportunity may play a more important role than host plant chemistry in explaining the lack of natural associations with some hosts.

  4. Host Plant Adaptation in Drosophila mettleri Populations

    PubMed Central

    Castrezana, Sergio; Bono, Jeremy M.

    2012-01-01

    The process of local adaptation creates diversity among allopatric populations, and may eventually lead to speciation. Plant-feeding insect populations that specialize on different host species provide an excellent opportunity to evaluate the causes of ecological specialization and the subsequent consequences for diversity. In this study, we used geographically separated Drosophila mettleri populations that specialize on different host cacti to examine oviposition preference for and larval performance on an array of natural and non-natural hosts (eight total). We found evidence of local adaptation in performance on saguaro cactus (Carnegiea gigantea) for populations that are typically associated with this host, and to chemically divergent prickly pear species (Opuntia spp.) in a genetically isolated population on Santa Catalina Island. Moreover, each population exhibited reduced performance on the alternative host. This finding is consistent with trade-offs associated with adaptation to these chemically divergent hosts, although we also discuss alternative explanations for this pattern. For oviposition preference, Santa Catalina Island flies were more likely to oviposit on some prickly pear species, but all populations readily laid eggs on saguaro. Experiments with non-natural hosts suggest that factors such as ecological opportunity may play a more important role than host plant chemistry in explaining the lack of natural associations with some hosts. PMID:22493678

  5. Host-microbe interactions in the developing zebrafish

    PubMed Central

    Kanther, Michelle; Rawls, John F.

    2010-01-01

    Summary of recent advances The amenability of the zebrafish to in vivo imaging and genetic analysis has fueled expanded use of this vertebrate model to investigate the molecular and cellular foundations of host-microbe relationships. Study of microbial encounters in zebrafish hosts has concentrated on developing embryonic and larval stages, when the advantages of the zebrafish model are maximized. A comprehensive understanding of these host-microbe interactions requires appreciation of the developmental context into which a microbe is introduced, as well as the effects of that microbial challenge on host ontogeny. In this review, we discuss how in vivo imaging and genetic analysis in zebrafish has advanced our knowledge of host-microbe interactions in the context of a developing vertebrate host. We focus on recent insights into immune cell ontogeny and function, commensal microbial relationships in the intestine, and microbial pathogenesis in zebrafish hosts. PMID:20153622

  6. Host defenses against cryptococcosis.

    PubMed

    Price, Michael S; Perfect, John R

    2011-01-01

    The interaction of pathogenic Cryptococcus species with their various hosts is somewhat unique compared to other fungal pathogens such as Aspergillus fumigatus and Candida albicans. Cryptococcus shares an intimate association with host immune cells, leading to enhanced intracellular growth. Furthermore, unlike most other fungal pathogens, the signs and symptoms of cryptococcal disease are typically self-inflicted by the host during the host's attempt to clear this invader from sensitive organ systems such as the central nervous system. In this review, we will summarize the story of host-Cryptococcus interactions to date and explore strategies to exploit the current knowledge for treatment of cryptococcal infections.

  7. Host and parasite genomics, an Australasian perspective.

    PubMed

    Peacock, C

    2010-08-01

    The last decade has seen rapid advances in the genetic technology that is allowing researchers to examine host-pathogen interactions at a whole organism level. The advent of 'affordable' post-genomic technology has opened up a world of proteomic, transcriptomic and metabolomic methodologies that have been utilized by research groups in the Australasian region to examine the hosts' response to parasitic infections. Significant contributions have been made to many areas of parasitic infections with particular strengths being in malaria vaccine development, genetic susceptibility to leishmaniasis, genomic and proteomic analysis of schistosomiasis and genetic determination of resistance to helminthes in domestic animals. This review highlights some of these studies that have made significant contributions to our knowledge of the pathogenesis of parasitic diseases with a particular emphasis placed on studies reported in the last couple of years.

  8. Host cells and methods for producing isoprenyl alkanoates

    SciTech Connect

    Lee, Taek Soon; Fortman, Jeffrey L.; Keasling, Jay D.

    2015-12-01

    The invention provides for a method of producing an isoprenyl alkanoate in a genetically modified host cell. In one embodiment, the method comprises culturing a genetically modified host cell which expresses an enzyme capable of catalyzing the esterification of an isoprenol and a straight-chain fatty acid, such as an alcohol acetyltransferase (AAT), wax ester synthase/diacylglycerol acyltransferase (WS/DGAT) or lipase, under a suitable condition so that the isoprenyl alkanoate is produced.

  9. Uncovering Wolbachia diversity upon artificial host transfer.

    PubMed

    Schneider, Daniela I; Riegler, Markus; Arthofer, Wolfgang; Merçot, Hervé; Stauffer, Christian; Miller, Wolfgang J

    2013-01-01

    The common endosymbiotic Wolbachia bacteria influence arthropod hosts in multiple ways. They are mostly recognized for their manipulations of host reproduction, yet, more recent studies demonstrate that Wolbachia also impact host behavior, metabolic pathways and immunity. Besides their biological and evolutionary roles, Wolbachia are new potential biological control agents for pest and vector management. Importantly, Wolbachia-based control strategies require controlled symbiont transfer between host species and predictable outcomes of novel Wolbachia-host associations. Theoretically, this artificial horizontal transfer could inflict genetic changes within transferred Wolbachia populations. This could be facilitated through de novo mutations in the novel recipient host or changes of haplotype frequencies of polymorphic Wolbachia populations when transferred from donor to recipient hosts. Here we show that Wolbachia resident in the European cherry fruit fly, Rhagoletis cerasi, exhibit ancestral and cryptic sequence polymorphism in three symbiont genes, which are exposed upon microinjection into the new hosts Drosophila simulans and Ceratitis capitata. Our analyses of Wolbachia in microinjected D. simulans over 150 generations after microinjection uncovered infections with multiple Wolbachia strains in trans-infected lines that had previously been typed as single infections. This confirms the persistence of low-titer Wolbachia strains in microinjection experiments that had previously escaped standard detection techniques. Our study demonstrates that infections by multiple Wolbachia strains can shift in prevalence after artificial host transfer driven by either stochastic or selective processes. Trans-infection of Wolbachia can claim fitness costs in new hosts and we speculate that these costs may have driven the shifts of Wolbachia strains that we saw in our model system.

  10. Coevolution of an avian host and its parasitic cuckoo.

    PubMed

    Servedio, Maria R; Lande, Russell

    2003-05-01

    We use a quantitative genetic model to examine the coevolution of host and cuckoo egg characters (termed "size" as a proxy for general appearance), host discrimination, and host and cuckoo population dynamics. A host decides whether to discard an egg using a comparison of the sizes of the eggs in her nest, which changes as host and cuckoo eggs evolve. Specifically, we assume that the probability that she discards the largest egg in her nest depends on how much larger it is than the second largest egg. This decision rule (i.e., the acceptable difference in egg sizes) also evolves, changing both the chance of successful rejection of a cuckoo egg in parasitized nests and the chance of mistaken rejection of a host egg in both parasitized and unparasitized nests. We find a stable equilibrium for coexistence of the host and cuckoo where there is cuckoo egg mimicry, evolutionary displacement of the host egg away from the cuckoo egg phenotype, and host discrimination against unusual eggs. Both host discrimination and host egg displacement are fairly weak at the equilibrium. Cuckoo egg mimicry, although imperfect, usually evolves more extensively and quickly than the responses of the host. Our model provides evidence for both the evolutionary equilibrium and evolutionary lag hypotheses of host acceptance of parasitic eggs.

  11. Glob-Hosts

    SciTech Connect

    Behlendorf, B.; Garlick, J.

    2007-08-31

    The glob-hosts utility manipulates hostlist strings in UNIX shell scripts. Hostlists are a parseable string representatin of list of hosts, which compress nicely when a group of hosts are named with contiguous numeric suffixes. For example, the hosts blue1, blue2, and blue3 can be represented by the hostlist string "blue1, blue2, blue3" or equivalently "blue[1-3]". The globhost utility cn peform the following operations on a hostlist string: count, size, expand, nth, union, minus, intersection, and exclude.

  12. Heritable variation in host tolerance and resistance inferred from a wild host-parasite system.

    PubMed

    Mazé-Guilmo, Elise; Loot, Géraldine; Páez, David J; Lefèvre, Thierry; Blanchet, Simon

    2014-03-22

    Hosts have evolved two distinct defence strategies against parasites: resistance (which prevents infection or limit parasite growth) and tolerance (which alleviates the fitness consequences of infection). However, heritable variation in resistance and tolerance and the genetic correlation between these two traits have rarely been characterized in wild host populations. Here, we estimate these parameters for both traits in Leuciscus burdigalensis, a freshwater fish parasitized by Tracheliastes polycolpus. We used a genetic database to construct a full-sib pedigree in a wild L. burdigalensis population. We then used univariate animal models to estimate inclusive heritability (i.e. all forms of genetic and non-genetic inheritance) in resistance and tolerance. Finally, we assessed the genetic correlation between these two traits using a bivariate animal model. We found significant heritability for resistance (H = 17.6%; 95% CI: 7.2-32.2%) and tolerance (H = 18.8%; 95% CI: 4.4-36.1%), whereas we found no evidence for the existence of a genetic correlation between these traits. Furthermore, we confirm that resistance and tolerance are strongly affected by environmental effects. Our results demonstrate that (i) heritable variation exists for parasite resistance and tolerance in wild host populations, and (ii) these traits can evolve independently in populations.

  13. Genetic Mapping

    MedlinePlus

    ... Fact Sheets Fact Sheets En Español: Mapeo Genético Genetic Mapping What is genetic mapping? How do researchers ... genetic map? What are genetic markers? What is genetic mapping? Among the main goals of the Human ...

  14. Genetic Counseling

    MedlinePlus

    ... Home > Pregnancy > Before or between pregnancies > Genetic counseling Genetic counseling E-mail to a friend Please fill ... a genetic counselor in your area. What is genetic counseling? Genetic counseling helps you understand how genes , ...

  15. Host-Specific Functional Significance of Caenorhabditis Gut Commensals

    PubMed Central

    Berg, Maureen; Zhou, Xiao Ying; Shapira, Michael

    2016-01-01

    The gut microbiota is an important contributor to host health and fitness. Given its importance, microbiota composition should not be left to chance. However, what determines this composition is far from clear, with results supporting contributions of both environmental factors and host genetics. To gauge the relative contributions of host genetics and environment, specifically the microbial diversity, we characterized the gut microbiotas of Caenorhabditis species spanning 200–300 million years of evolution, and raised on different composted soil environments. Comparisons were based on 16S rDNA deep sequencing data, as well as on functional evaluation of gut isolates. Worm microbiotas were distinct from those in their respective soil environment, and included bacteria previously identified as part of the C. elegans core microbiota. Microbiotas differed between experiments initiated with different soil communities, but within each experiment, worm microbiotas clustered according to host identity, demonstrating a dominant contribution of environmental diversity, but also a significant contribution of host genetics. The dominance of environmental contributions hindered identification of host-associated microbial taxa from 16S data. Characterization of gut isolates from C. elegans and C. briggsae, focusing on the core family Enterobacteriaceae, were also unable to expose phylogenetic distinctions between microbiotas of the two species. However, functional evaluation of the isolates revealed host-specific contributions, wherein gut commensals protected their own host from infection, but not a non-host. Identification of commensal host-specificity at the functional level, otherwise overlooked in standard sequence-based analyses, suggests that the contribution of host genetics to shaping of gut microbiotas may be greater than previously realized. PMID:27799924

  16. Host specificity in parasitic plants—perspectives from mistletoes

    PubMed Central

    Okubamichael, Desale Y.; Griffiths, Megan E.; Ward, David

    2016-01-01

    Host specificity has been investigated for centuries in mistletoes, viruses, insects, parasitoids, lice and flukes, yet it is poorly understood. Reviewing the numerous studies on mistletoe host specificity may contribute to our understanding of these plants and put into context the dynamics at work in root parasitic plants and animal parasites. The mechanisms that determine host specificity in mistletoes are not as well documented and understood as those in other groups of parasites. To rectify this, we synthesized the available literature and analyzed data compiled from herbaria, published monographs and our own field studies in South Africa. As for other groups of parasites, multiple factors influence mistletoe host specificity. Initially, pollination affects gene flow. Subsequently, seed dispersal vectors (birds and marsupials), host abundance and compatibility (genetic, morphological, physiological and chemical), history and environmental conditions affect the interaction of mistletoes and their hosts and determine host specificity. Mistletoe–host network analyses and a geographic mosaic approach combined with long-term monitoring of reciprocal transplant experiments, genetic analyses of confined mistletoe populations and comparative phylogenetic studies could provide further insights to our understanding of host specificity. Some of these approaches have been used to study animal–plant interactions and could be adopted to test and evaluate host specificity in mistletoes at local and larger geographic scales. PMID:27658817

  17. Paper Genetic Engineering.

    ERIC Educational Resources Information Center

    MacClintic, Scott D.; Nelson, Genevieve M.

    Bacterial transformation is a commonly used technique in genetic engineering that involves transferring a gene of interest into a bacterial host so that the bacteria can be used to produce large quantities of the gene product. Although several kits are available for performing bacterial transformation in the classroom, students do not always…

  18. Genetically Engineered Cyanobacteria

    NASA Technical Reports Server (NTRS)

    Zhou, Ruanbao (Inventor); Gibbons, William (Inventor)

    2015-01-01

    The disclosed embodiments provide cyanobacteria spp. that have been genetically engineered to have increased production of carbon-based products of interest. These genetically engineered hosts efficiently convert carbon dioxide and light into carbon-based products of interest such as long chained hydrocarbons. Several constructs containing polynucleotides encoding enzymes active in the metabolic pathways of cyanobacteria are disclosed. In many instances, the cyanobacteria strains have been further genetically modified to optimize production of the carbon-based products of interest. The optimization includes both up-regulation and down-regulation of particular genes.

  19. The roles of host factors in tombusvirus RNA recombination.

    PubMed

    Nagy, Peter D

    2011-01-01

    RNA viruses are the champions of evolution due to high frequency mutations and genetic recombination occurring during virus replication. These genetic events are due to the error-prone nature of viral RNA-dependent RNA polymerases (RdRp). Recently emerging models on viral RNA recombination, however, also include key roles for host and environmental factors. Accordingly, genome-wide screens and global proteomics approaches with Tomato bushy stunt virus (TBSV) and yeast (Saccharomyces cerevisiae) as a model host have identified 38 host proteins affecting viral RNA recombination. Follow-up studies have identified key host proteins and cellular pathways involved in TBSV RNA recombination. In addition, environmental factors, such as salt stress, have been shown to affect TBSV recombination via influencing key host or viral factors involved in the recombination process. These advances will help build more accurate models on viral recombination, evolution, and adaptation.

  20. Using host response modifiers in the treatment of periodontal disease.

    PubMed

    Novak, M John; Donley, Timothy G

    2002-01-01

    Periodontal disease is the result of a complex interaction between microbial plaque, the host's inflammatory response to the plaque, and host modifying factors (e.g., smoking, diabetes, genetics) that may have an impact on the disease process. It is known that plaque initiates periodontal disease but that the host response is responsible for the destruction of periodontal tissues. This article describes why host response modifiers may be used to help control inflammation and tissue destruction as part of the initial phase of periodontal therapy in selected patient groups.

  1. Host defenses in subcutaneous mycoses.

    PubMed

    Vera-Cabrera, Lucio; Salinas-Carmona, Mario Cesar; Waksman, Noemi; Messeguer-Pérez, Jonathan; Ocampo-Candiani, Jorge; Welsh, Oliverio

    2012-01-01

    Subcutaneous mycoses include diverse clinical syndromes, characterized by invasion of the skin and subcutaneous tissue by saprobic fungi. Individuals living in rural areas constantly suffer lesions or trauma; however, only a few of them develop disease. In this contribution, we describe recent advances in the understanding of the virulence of these organisms, focusing on the most prevalent infections, sporotrichosis, chromoblastomycosis, and mycetoma. Although these infectious diseases are considered neglected tropical diseases, modern molecular techniques have been able to identify the etiologic agents and observe variations in the former monolithic concept of the species, which was based mostly on morphologic characteristics. The complete genetic characterization of the causative agents, along with that of their host, will help in the understanding of the factors on which the development of these infections depends.

  2. [Genetics and genetic counseling].

    PubMed

    Izzi, Claudia; Liut, Francesca; Dallera, Nadia; Mazza, Cinzia; Magistroni, Riccardo; Savoldi, Gianfranco; Scolari, Francesco

    2016-01-01

    Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most frequent genetic disease, characterized by progressive development of bilateral renal cysts. Two causative genes have been identified: PKD1 and PKD2. ADPKD phenotype is highly variable. Typically, ADPKD is an adult onset disease. However, occasionally, ADPKD manifests as very early onset disease. The phenotypic variability of ADPKD can be explained at three genetic levels: genic, allelic and gene modifier effects. Recent advances in molecular screening for PKD gene mutations and the introduction of the new next generation sequencing (NGS)- based genotyping approach have generated considerable improvement regarding the knowledge of genetic basis of ADPKD. The purpose of this article is to provide a comprehensive review of the genetics of ADPKD, focusing on new insights in genotype-phenotype correlation and exploring novel clinical approach to genetic testing. Evaluation of these new genetic information requires a multidisciplinary approach involving a nephrologist and a clinical geneticist.

  3. Lichenicolous fungi show population subdivision by host species but do not share population history with their hosts.

    PubMed

    Werth, Silke; Millanes, Ana María; Wedin, Mats; Scheidegger, Christoph

    2013-01-01

    Lichenicolous fungi are a species-rich biological group growing on lichen thalli. Here, we analyze the genetic structure of the lichenicolous basidiomycete Tremella lobariacearum and three host species (Lobaria pulmonaria, Lobaria macaronesica, and Lobaria immixta) in Macaronesia. We used ordination and analysis of molecular variance to investigate the structuring of genetic variation, and a simulation test to investigate whether rDNA haplotypes of T. lobariacearum were significantly associated with host species. To investigate the evolutionary and demographic history of the lichenicolous fungus and its hosts, we used coalescent samplers to generate trees, and Bayesian skyline plots. We found that the hosts were most important in structuring populations of the lichenicolous species. Despite their wide geographic distribution, the same haplotypes of T. lobariacearum consistently associated with a given host species. Our results suggest that the Lobaria hosts create a selective environment for the lichenicolous fungus. Both the pathogen and the host populations exhibited substantial genetic structure. However, evolutionary and demographic histories differed between the parasite and its hosts, as evidenced by different divergence times and tree topologies.

  4. Broad host range plasmids.

    PubMed

    Jain, Aayushi; Srivastava, Preeti

    2013-11-01

    Plasmids are and will remain important cloning vehicles for biotechnology. They have also been associated with the spread of a number of diseases and therefore are a subject of environmental concern. With the advent of sequencing technologies, the database of plasmids is increasing. It will be of immense importance to identify the various bacterial hosts in which the plasmid can replicate. The present review article describes the features that confer broad host range to the plasmids, the molecular basis of plasmid host range evolution, and applications in recombinant DNA technology and environment.

  5. Susceptibility to Phytophthora ramorum in a key infectious host: landscape variation in host genotype, host phenotype, and environmental factors.

    PubMed

    Anacker, Brian L; Rank, Nathan E; Hüberli, Daniel; Garbelotto, Matteo; Gordon, Sarah; Harnik, Tami; Whitkus, Richard; Meentemeyer, Ross

    2008-01-01

    Sudden oak death is an emerging forest disease caused by the invasive pathogen Phytophthora ramorum. Genetic and environmental factors affecting susceptibility to P. ramorum in the key inoculum-producing host tree Umbellularia californica (bay laurel) were examined across a heterogeneous landscape in California, USA. Laboratory susceptibility trials were conducted on detached leaves and assessed field disease levels for 97 host trees from 12 225-m(2) plots. Genotype and phenotype characteristics were assessed for each tree. Effects of plot-level environmental conditions (understory microclimate, amount of solar radiation and topographic moisture potential) on disease expression were also evaluated. Susceptibility varied significantly among U. californica trees, with a fivefold difference in leaf lesion size. Lesion size was positively related to leaf area, but not to other phenotypic traits or to field disease level. Genetic diversity was structured at three spatial scales, but primarily among individuals within plots. Lesion size was significantly related to amplified fragment length polymorphism (AFLP) markers, but local environment explained most variation in field disease level. Thus, substantial genetic variation in susceptibility to P. ramorum occurs in its principal foliar host U. californica, but local environment mediates expression of susceptibility in nature.

  6. The alien replicon: Artificial genetic constructs to direct the synthesis of transmissible self-replicating RNAs: In vivo synthesised heterologous (alien) RNA constructs are capable of initiating self-replication following transmission to the host organism.

    PubMed

    Kochetov, Alex V

    2014-12-01

    Artificial genetic constructs that direct the synthesis of self-replicating RNA molecules are used widely to induce gene silencing, for bioproduction, and for vaccination. Interestingly, one variant of the self-replicon has not been discussed in the literature: namely, transgenic organisms that synthesise alien replicons. For example, plant cells may be easily genetically modified to produce bacteriophages or insect viruses. Alien replicon-producing organisms (ARPOs) may serve as a unique tool for biocontrol or to selectively influence the characteristics of a target organism. The ARPO approach would have to meet strict biosafety criteria, and its practical applications are problematic. However, a discussion on ARPO applicability would be valuable to outline the full set of options available in the bioengineering toolbox. In this paper, RNA replicons for bioengineering are reviewed briefly, and the ARPO approach is discussed.

  7. A Full-Length Infectious cDNA Clone of Zika Virus from the 2015 Epidemic in Brazil as a Genetic Platform for Studies of Virus-Host Interactions and Vaccine Development

    PubMed Central

    Tsetsarkin, Konstantin A.; Kenney, Heather; Chen, Rubing; Liu, Guangping; Manukyan, Hasmik; Whitehead, Stephen S.; Laassri, Majid

    2016-01-01

    ABSTRACT An arthropod-borne virus, Zika virus (ZIKV), has recently emerged as a major human pathogen. Associated with complications during perinatal development and Guillain-Barré syndrome in adults, ZIKV raises new challenges for understanding the molecular determinants of flavivirus pathogenesis. This underscores the necessity for the development of a reverse genetic system based on an epidemic ZIKV strain. Here, we describe the generation and characterization in cell cultures of an infectious cDNA clone of ZIKV isolated from the 2015 epidemic in Brazil. The cDNA-derived ZIKV replicated efficiently in a variety of cell lines, including those of both neuronal and placental origin. We observed that the growth of cDNA-derived virus was attenuated compared to the growth of the parental isolate in most cell lines, which correlates with substantial differences in sequence heterogeneity between these viruses that were determined by deep-sequencing analysis. Our findings support the role of genetic diversity in maintaining the replicative fitness of viral populations under changing conditions. Moreover, these results indicate that caution should be exercised when interpreting the results of reverse-genetics experiments in attempts to accurately predict the biology of natural viruses. Finally, a Vero cell-adapted cDNA clone of ZIKV was generated that can be used as a convenient platform for studies aimed at the development of ZIKV vaccines and therapeutics. PMID:27555311

  8. Host-Specific Patterns of Genetic Diversity among IncI1-Iγ and IncK Plasmids Encoding CMY-2 β-Lactamase in Escherichia coli Isolates from Humans, Poultry Meat, Poultry, and Dogs in Denmark

    PubMed Central

    Hansen, Katrine Hartung; Bortolaia, Valeria; Nielsen, Christine Ahl; Nielsen, Jesper Boye; Agersø, Yvonne

    2016-01-01

    ABSTRACT CMY-2 is the most common plasmid-mediated AmpC β-lactamase in Escherichia coli isolates of human and animal origin. The aim of this study was to elucidate the epidemiology of CMY-2-producing E. coli in Denmark. Strain and plasmid relatedness was studied in 93 CMY-2-producing clinical and commensal E. coli isolates collected from 2006 to 2012 from humans, retail poultry meat, broilers, and dogs. Multilocus sequence typing (MLST), antimicrobial susceptibility testing, and conjugation were performed in conjunction with plasmid replicon typing, plasmid multilocus sequence typing (pMLST), restriction fragment length polymorphism (RFLP), and sequencing of selected blaCMY-2-harboring plasmids. MLST revealed high strain diversity, with few E. coli lineages occurring in multiple host species and sample types. blaCMY-2 was detected on plasmids in 83 (89%) isolates. Most (75%) of the plasmids were conjugative and did not (96%) cotransfer resistance to antimicrobials other than cephalosporins. The main replicon types identified were IncI1-Iγ (55%) and IncK (39%). Isolates from different host species mainly carried distinct plasmid subtypes. Seven of the 18 human isolates harbored IncI1-Iγ/sequence type 2 (ST2), IncI1-Iγ/ST12, or IncK plasmids highly similar to those found among animal isolates, even though highly related human and animal plasmids differed by nonsynonymous single nucleotide polymorphisms (SNPs) or insertion sequence elements. This study clearly demonstrates that the epidemiology of CMY-2 can be understood only by thorough plasmid characterization. To date, the spread of this β-lactam resistance determinant in Denmark is mainly associated with IncK and IncI1-Iγ plasmids that are generally distributed according to host-specific patterns. These baseline data will be useful to assess the consequences of the increasing human exposure to CMY-2-producing E. coli via animal sources. IMPORTANCE CMY-2 is the most common plasmid-mediated AmpC

  9. New Genetics

    MedlinePlus

    ... Home > Science Education > The New Genetics The New Genetics Living Laboratories Classroom Poster Order a Free Copy ... Piece to a Century-Old Evolutionary Puzzle Computing Genetics Model Organisms RNA Interference The New Genetics is ...

  10. Genetic Disorders

    MedlinePlus

    ... Management Education & Events Advocacy For Patients About ACOG Genetic Disorders Home For Patients Search FAQs Genetic Disorders ... Spanish Genetic Disorders FAQ094, April 2014 PDF Format Genetic Disorders Pregnancy What are genes? What are chromosomes? ...

  11. Medical genetics

    SciTech Connect

    Nora, J.J.; Fraser, F.C.

    1989-01-01

    This book presents a discussion of medical genetics for the practitioner treating or counseling patients with genetic disease. It includes a discussion of the relationship of heredity and diseases, the chromosomal basis for heredity, gene frequencies, and genetics of development and maldevelopment. The authors also focus on teratology, somatic cell genetics, genetics and cancer, genetics of behavior.

  12. Revisiting the particular role of host shifts in initiating insect speciation.

    PubMed

    Forbes, Andrew A; Devine, Sara N; Hippee, Alaine C; Tvedte, Eric S; Ward, Anna K G; Widmayer, Heather A; Wilson, Caleb J

    2017-01-04

    The notion that shifts to new hosts can initiate insect speciation is more than 150 years old, yet widespread conflation with paradigms of sympatric speciation has led to confusion about how much support exists for this hypothesis. Here, we review 85 insect systems and evaluate the relationship between host shifting, reproductive isolation, and speciation. We sort insects into five categories: (1) systems in which a host shift has initiated speciation; (2) systems in which a host shift has made a contribution to speciation; (3) systems in which a host shift has caused the evolution of new reproductive isolating barriers; (4) systems with host-associated genetic differences; and (5) systems with no evidence of host-associated genetic differences. We find host-associated genetic structure in 65 systems, 43 of which show that host shifts have resulted in the evolution of new reproductive barriers. Twenty-six of the latter also support a role for host shifts in speciation, including eight studies that definitively support the hypothesis that a host shift has initiated speciation. While this review is agnostic as to the fraction of all insect speciation events to which host shifts have contributed, it clarifies that host shifts absolutely can and do initiate speciation.

  13. Identification of a classical mutant in the industrial host Aspergillus niger by systems genetics: LaeA is required for citric acid production and regulates the formation of some secondary metabolites

    DOE PAGES

    Niu, Jing; Arentshorst, Mark; Nair, P. Deepa S.; ...

    2015-11-13

    The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. nigermore » has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a ΔlaeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. As a result, we show that our systems genetics approach is a powerful tool to identify trait mutations.« less

  14. Identification of a classical mutant in the industrial host Aspergillus niger by systems genetics: LaeA is required for citric acid production and regulates the formation of some secondary metabolites

    SciTech Connect

    Niu, Jing; Arentshorst, Mark; Nair, P. Deepa S.; Dai, Ziyu; Baker, Scott E.; Frisvad, Jens C.; Nielsen, Kristian F.; Punt, Peter J.; Ram, Arthur F. J.

    2015-11-13

    The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. niger has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a ΔlaeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. As a result, we show that our systems genetics approach is a powerful tool to identify trait mutations.

  15. Identification of a Classical Mutant in the Industrial Host Aspergillus niger by Systems Genetics: LaeA Is Required for Citric Acid Production and Regulates the Formation of Some Secondary Metabolites.

    PubMed

    Niu, Jing; Arentshorst, Mark; Nair, P Deepa S; Dai, Ziyu; Baker, Scott E; Frisvad, Jens C; Nielsen, Kristian F; Punt, Peter J; Ram, Arthur F J

    2015-11-13

    The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. niger has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a ΔlaeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. Finally, we show that our systems genetics approach is a powerful tool to identify trait mutations.

  16. Identification of a Classical Mutant in the Industrial Host Aspergillus niger by Systems Genetics: LaeA Is Required for Citric Acid Production and Regulates the Formation of Some Secondary Metabolites

    PubMed Central

    Niu, Jing; Arentshorst, Mark; Nair, P. Deepa S.; Dai, Ziyu; Baker, Scott E.; Frisvad, Jens C.; Nielsen, Kristian F.; Punt, Peter J.; Ram, Arthur F.J.

    2015-01-01

    The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. niger has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a ΔlaeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. Finally, we show that our systems genetics approach is a powerful tool to identify trait mutations. PMID:26566947

  17. Genetic diversity and population structure of Synthesium pontoporiae (Digenea, Brachycladiidae) linked to its definitive host stocks, the endangered Franciscana dolphin, Pontoporia blainvillei (Pontoporiidae) off the coast of Brazil and Argentina.

    PubMed

    Marigo, J; Cunha, H A; Bertozzi, C P; Souza, S P; Rosas, F C W; Cremer, M J; Barreto, A S; de Oliveira, L R; Cappozzo, H L; Valente, A L S; Santos, C P; Vicente, A C P

    2015-01-01

    Pontoporia blainvillei (Gervais and d'Orbigny, 1844) is an endangered small cetacean endemic to South America with four Franciscana Management Areas (FMA) recognized as different population stocks. The role of the intestinal parasite Synthesium pontoporiae (Digenea: Brachycladiidae) as a possible biological marker to differentiate P. blainvillei stocks was evaluated using nuclear and mitochondrial DNA markers. Internal transcribed sequence 1 and 2 (ITS1 and ITS2) regions of S. pontoporiae did not show intraspecific variability. The mitochondrial NADH dehydrogenase subunit 3 (ND3) and cytochrome oxidase subunit I (COI) gene sequences suggested lack of population structure in S. pontoporiae and population expansion. The apparent panmixia of S. pontoporiae may be due to the high mobility of one or more of its intermediary hosts. Alternatively, it may be due to the small sample size. This result is incongruent with the previously proposed FMA.

  18. [Parasite-host relationships and treatment].

    PubMed

    Vuitton, Dominique-Angèle; Mantion, Georges; Bartholomot, Brigitte; Giraudoux, Patrick; Bresson-Hadni, Solange

    2008-01-01

    Alveolar echinococcosis (AE) is a parasitic disease caused by intrahepatic growth of the larval stage of the cestode Echinococcus multilocularis. The main definitive host in Europe is the fox. The adult worms live in the fox intestine and their oncospheres are disseminated by faeces. Wolves, dogs and cats may also serve as definitive hosts. Small rodents--especially voles in Europe and small lagomorphs in Asia--are the natural intermediate hosts. The tumour-like larva is composed of multiple vesicles which produce protoscoleces, the fertile stage of the E. multilocularis metacestode. Carnivores are infected by preying on infected rodents. Like rodents, humans are intermediate hosts and are infected either by eating uncooked vegetables and berries contaminated by faeces of infected carnivores, or by touching such animals. Humans are naturally resistant to metacestode development. Genetic characteristics are involved in susceptibility/resistance to E. multilocularis metacestodes. In humans and other intermediate animal hosts, immune suppression enhances parasite growth, which is normally controlled by cytotoxic mechanisms and delayed-type hypersensitivity. Tolerance of E. multilocularis is due in part to parasite characteristics (especially carbohydrate antigens of the laminated layer) and in part to the "anti-inflammatory/tolerogenic" cytokines IL-10 and TGF-beta. Treatment with interferon-a restores a cytokine balance favorable to the host and might be a new therapeutic option for AE patients. Vaccination is a scientifically sound but economically and politically Utopian means of preventing the disease. Prevention thus relies on simple lifestyle measures: cooking potentially contaminated food, regular treatment of domestic animals with praziquantel, and precautions when touching potentially infected definitive hosts (foxes and dogs).

  19. NASA HOST project overview

    NASA Technical Reports Server (NTRS)

    Sokolowski, Daniel E.

    1989-01-01

    NASA's Hot Section Technology (HOST) program has developed improved analytical models for the aerothermal environment, thermomechanical loading, material behavior, structural response, and service life of aircraft gas turbine engines' hot section components. These models, in conjunction with sophisticated computer codes, can be used in design analyses of critical combustor and turbine elements. Toward these ends, efforts were undertaken in instrumentation, combustion, turbine heat transfer, structural analysis, fatigue-fracture, and surface protection. Attention is presently given to the organization of HOST activities and their specific subject matter.

  20. Host age modulates within-host parasite competition

    PubMed Central

    Izhar, Rony; Routtu, Jarkko; Ben-Ami, Frida

    2015-01-01

    In many host populations, one of the most striking differences among hosts is their age. While parasite prevalence differences in relation to host age are well known, little is known on how host age impacts ecological and evolutionary dynamics of diseases. Using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa, we examined how host age at exposure influences within-host parasite competition and virulence. We found that multiply-exposed hosts were more susceptible to infection and suffered higher mortality than singly-exposed hosts. Hosts oldest at exposure were least often infected and vice versa. Furthermore, we found that in young multiply-exposed hosts competition was weak, allowing coexistence and transmission of both parasite clones, whereas in older multiply-exposed hosts competitive exclusion was observed. Thus, age-dependent parasite exposure and host demography (age structure) could together play an important role in mediating parasite evolution. At the individual level, our results demonstrate a previously unnoticed interaction of the host's immune system with host age, suggesting that the specificity of immune function changes as hosts mature. Therefore, evolutionary models of parasite virulence might benefit from incorporating age-dependent epidemiological parameters. PMID:25994010

  1. Evolution and genetic diversity of Theileria.

    PubMed

    Sivakumar, Thillaiampalam; Hayashida, Kyoko; Sugimoto, Chihiro; Yokoyama, Naoaki

    2014-10-01

    Theileria parasites infect a wide range of domestic and wild ruminants worldwide, causing diseases with varying degrees of severity. A broad classification, based on the parasite's ability to transform the leukocytes of host animals, divides Theileria into two groups, consisting of transforming and non-transforming species. The evolution of transforming Theileria has been accompanied by drastic changes in its genetic makeup, such as acquisition or expansion of gene families, which are thought to play critical roles in the transformation of host cells. Genetic variation among Theileria parasites is sometimes linked with host specificity and virulence in the parasites. Immunity against Theileria parasites primarily involves cell-mediated immune responses in the host. Immunodominance and major histocompatibility complex class I phenotype-specificity result in a host immunity that is tightly focused and strain-specific. Immune escape in Theileria is facilitated by genetic diversity in its antigenic determinants, which potentially results in a loss of T cell receptor recognition in its host. In the recent past, several reviews have focused on genetic diversity in the transforming species, Theileriaparva and Theileriaannulata. In contrast, genetic diversity in Theileriaorientalis, a benign non-transforming parasite, which occasionally causes disease outbreaks in cattle, has not been extensively examined. In this review, therefore, we provide an outline of the evolution of Theileria, which includes T. orientalis, and discuss the possible mechanisms generating genetic diversity among parasite populations. Additionally, we discuss the potential implications of a genetically diverse parasite population in the context of Theileria vaccine development.

  2. Medical genetics

    SciTech Connect

    Jorde, L.B.; Carey, J.C.; White, R.L.

    1995-10-01

    This book on the subject of medical genetics is a textbook aimed at a very broad audience: principally, medical students, nursing students, graduate, and undergraduate students. The book is actually a primer of general genetics as applied to humans and provides a well-balanced introduction to the scientific and clinical basis of human genetics. The twelve chapters include: Introduction, Basic Cell Biology, Genetic Variation, Autosomal Dominant and Recessive Inheritance, Sex-linked and Mitochondrial Inheritance, Clinical Cytogenetics, Gene Mapping, Immunogenetics, Cancer Genetics, Multifactorial Inheritance and Common Disease, Genetic Screening, Genetic Diagnosis and Gene Therapy, and Clinical Genetics and Genetic Counseling.

  3. Genetic algorithms

    NASA Technical Reports Server (NTRS)

    Wang, Lui; Bayer, Steven E.

    1991-01-01

    Genetic algorithms are mathematical, highly parallel, adaptive search procedures (i.e., problem solving methods) based loosely on the processes of natural genetics and Darwinian survival of the fittest. Basic genetic algorithms concepts are introduced, genetic algorithm applications are introduced, and results are presented from a project to develop a software tool that will enable the widespread use of genetic algorithm technology.

  4. A refined genetic model for the Laisvall and Vassbo Mississippi Valley-type sandstone-hosted deposits, Sweden: constraints from paragenetic studies, organic geochemistry, and S, C, N, and Sr isotope data

    NASA Astrophysics Data System (ADS)

    Saintilan, Nicolas J.; Spangenberg, Jorge E.; Samankassou, Elias; Kouzmanov, Kalin; Chiaradia, Massimo; Stephens, Michael B.; Fontboté, Lluís

    2016-06-01

    The current study has aimed to refine the previously proposed two-fluid mixing model for the Laisvall (sphalerite Rb-Sr age of 467 ± 5 Ma) and Vassbo Mississippi Valley-type deposits hosted in Ediacaran to Cambrian sandstone, Sweden. Premineralization cements include authigenic monazite, fluorapatite, and anatase in the Upper Sandstone at Laisvall, reflecting anoxic conditions during sandstone burial influenced by the euxinic character of the overlying carbonaceous middle Cambrian to Lower Ordovician Alum Shale Formation ( δ 13Corg = -33.0 to -29.5 ‰, δ 15Norg = 1.5 to 3.3 ‰, 0.33 to 3.03 wt% C, 0.02 to 0.08 wt% N). The available porosity for epigenetic mineralization, including that produced by subsequent partial dissolution of pre-Pb-Zn sulfide calcite and barite cements, was much higher in calcite- and barite-cemented sandstone paleoaquifers (29 % by QEMSCAN mapping) than in those mainly cemented by quartz (8 %). A major change in the Laisvall plumbing system is recognized by the transition from barite cementation to Pb-Zn sulfide precipitation in sandstone. Ba-bearing, reduced, and neutral fluids had a long premineralization residence time (highly radiogenic 87S/86Sr ratios of 0.718 to 0.723) in basement structures. As a result of an early Caledonian arc-continent collision and the development of a foreland basin, fluids migrated toward the craton and expelled Ba-bearing fluids from their host structures into overlying sandstone where they deposited barite upon mixing with a sulfate pool ( δ 34Sbarite = 14 to 33 ‰). Subsequently, slightly acidic brines initially residing in pre-Ediacaran rift sediments in the foredeep of the early Caledonian foreland basin migrated through the same plumbing system and acquired metals on the way. The bulk of Pb-Zn mineralization formed at temperatures between 120 and 180 °C by mixing of these brines with a pool of H2S ( δ 34S = 24 to 29 ‰) produced via thermochemical sulfate reduction (TSR) with oxidation of

  5. Host shift and speciation in a coral-feeding nudibranch

    PubMed Central

    Faucci, Anuschka; Toonen, Robert J; Hadfield, Michael G

    2006-01-01

    While the role of host preference in ecological speciation has been investigated extensively in terrestrial systems, very little is known in marine environments. Host preference combined with mate choice on the preferred host can lead to population subdivision and adaptation leading to host shifts. We use a phylogenetic approach based on two mitochondrial genetic markers to disentangle the taxonomic status and to investigate the role of host specificity in the speciation of the nudibranch genus Phestilla (Gastropoda, Opisthobranchia) from Guam, Palau and Hawaii. Species of the genus Phestilla complete their life cycle almost entirely on their specific host coral (species of Porites, Goniopora and Tubastrea). They reproduce on their host coral and their planktonic larvae require a host-specific chemical cue to metamorphose and settle onto their host. The phylogenetic trees of the combined cytochrome oxidase I and ribosomal 16S gene sequences clarify the relationship among species of Phestilla identifying most of the nominal species as monophyletic clades. We found a possible case of host shift from Porites to Goniopora and Tubastrea in sympatric Phestilla spp. This represents one of the first documented cases of host shift as a mechanism underlying speciation in a marine invertebrate. Furthermore, we found highly divergent clades within Phestilla sp. 1 and Phestilla minor (8.1–11.1%), suggesting cryptic speciation. The presence of a strong phylogenetic signal for the coral host confirms that the tight link between species of Phestilla and their host coral probably played an important role in speciation within this genus. PMID:17134995

  6. Host plant resistance against tomato spotted wilt virus in peanut (Arachis hypogaea) and its impact on susceptibility to the virus, virus population genetics, and vector feeding behavior and survival.

    PubMed

    Sundaraj, Sivamani; Srinivasan, Rajagopalbabu; Culbreath, Albert K; Riley, David G; Pappu, Hanu R

    2014-02-01

    Tomato spotted wilt virus (TSWV) severely affects peanut production in the southeastern United States. Breeding efforts over the last three decades resulted in the release of numerous peanut genotypes with field resistance to TSWV. The degree of field resistance in these genotypes has steadily increased over time, with recently released genotypes exhibiting a higher degree of field resistance than older genotypes. However, most new genotypes have never been evaluated in the greenhouse or laboratory against TSWV or thrips, and the mechanism of resistance is unknown. In this study, TSWV-resistant and -susceptible genotypes were subjected to TSWV mechanical inoculation. The incidence of TSWV infection was 71.7 to 87.2%. Estimation of TSWV nucleocapsid (N) gene copies did not reveal significant differences between resistant and susceptible genotypes. Parsimony and principal component analyses of N gene nucleotide sequences revealed inconsistent differences between virus isolates collected from resistant and susceptible genotypes and between old (collected in 1998) and new (2010) isolates. Amino acid sequence analyses indicated consistent differences between old and new isolates. In addition, we found evidence for overabundance of nonsynonymous substitutions. However, there was no evidence for positive selection. Purifying selection, population expansion, and differentiation seem to have influenced the TSWV populations temporally rather than positive selection induced by host resistance. Choice and no-choice tests indicated that resistant and susceptible genotypes differentially affected thrips feeding and survival. Thrips feeding and survival were suppressed on some resistant genotypes compared with susceptible genotypes. These findings reveal how TSWV resistance in peanut could influence evolution, epidemiology, and management of TSWV.

  7. A quantitative trait locus for recognition of foreign eggs in the host of a brood parasite.

    PubMed

    Martín-Gálvez, D; Soler, J J; Martínez, J G; Krupa, A P; Richard, M; Soler, M; Møller, A P; Burke, T

    2006-03-01

    Avian brood parasites reduce the reproductive output of their hosts and thereby select for defence mechanisms such as ejection of parasitic eggs. Such defence mechanisms simultaneously select for counter-defences in brood parasites, causing a coevolutionary arms race. Although coevolutionary models assume that defences and counter-defences are genetically influenced, this has never been demonstrated for brood parasites. Here, we give strong evidence for genetic differences between ejector and nonejectors, which could allow the study of such host defence at the genetic level, as well as studies of maintenance of genetic variation in defences. Briefly, we found that magpies, that are the main host of the great spotted cuckoo in Europe, have alleles of one microsatellite locus (Ase64) that segregate between accepters and rejecters of experimental parasitic eggs. Furthermore, differences in ejection rate among host populations exploited by the brood parasite covaried significantly with the genetic distance for this locus.

  8. Genetic diversity and population genetics of large lungworms (Dictyocaulus, Nematoda) in wild deer in Hungary.

    PubMed

    Ács, Zoltán; Hayward, Alexander; Sugár, László

    2016-09-01

    Dictyocaulus nematode worms live as parasites in the lower airways of ungulates and can cause significant disease in both wild and farmed hosts. This study represents the first population genetic analysis of large lungworms in wildlife. Specifically, we quantify genetic variation in Dictyocaulus lungworms from wild deer (red deer, fallow deer and roe deer) in Hungary, based on mitochondrial cytochrome c oxidase subunit 1 (cox1) sequence data, using population genetic and phylogenetic analyses. The studied Dictyocaulus taxa display considerable genetic diversity. At least one cryptic species and a new parasite-host relationship are revealed by our molecular study. Population genetic analyses for Dictyocaulus eckerti revealed high gene flow amongst weakly structured spatial populations that utilise the three host deer species considered here. Our results suggest that D. eckerti is a widespread generalist parasite in ungulates, with a diverse genetic backround and high evolutionary potential. In contrast, evidence of cryptic genetic structure at regional geographic scales was observed for Dictyocaulus capreolus, which infects just one host species, suggesting it is a specialist within the studied area. D. capreolus displayed lower genetic diversity overall, with only moderate gene flow compared to the closely related D. eckerti. We suggest that the differing vagility and dispersal behaviour of hosts are important contributing factors to the population structure of lungworms, and possibly other nematode parasites with single-host life cycles. Our findings are of relevance for the management of lungworms in deer farms and wild deer populations.

  9. Models and approaches to dissect host-symbiont specificity.

    PubMed

    Mandel, Mark J

    2010-11-01

    Animals are symbiotic superorganisms, composed of eukaryotic cells and specific microbial residents that perform essential functions for their host. As humans, we are beginning to appreciate the diversity and function of our own microbiota, but model systems are leading the field in illustrating the molecular mechanisms that allow specific relationships to be recapitulated during each host generation. This review focuses on models in which genetic screens, coupled with genomics, imaging, phylogenetics and population biology, have begun to allow a remarkably detailed investigation into the molecular dissection of the evolution of host specificity in animal symbionts.

  10. Monitoring host responses to the gut microbiota.

    PubMed

    Lichtman, Joshua S; Sonnenburg, Justin L; Elias, Joshua E

    2015-09-01

    The gastrointestinal (GI) ecosystem is increasingly understood to be a fundamental component of health, and has been identified as a new focal point for diagnosing, correcting and preventing countless disorders. Shotgun DNA sequencing has emerged as the dominant technology for determining the genetic and microbial composition of the gut microbiota. This technology has linked microbiota dysbioses to numerous GI diseases including inflammatory bowel disease, obesity and allergy, and to non-GI diseases like autism and depression. The importance of establishing causality in the deterioration of the host-microbiota relationship is well appreciated; however, discovery of candidate molecules and pathways that underlie mechanisms remains a major challenge. Targeted approaches, transcriptional assays, cytokine panels and imaging analyses, applied to animals, have yielded important insight into host responses to the microbiota. However, non-invasive, hypothesis-independent means of measuring host responses in humans are necessary to keep pace with similarly unbiased sequencing efforts that monitor microbes. Mass spectrometry-based proteomics has served this purpose in many other fields, but stool proteins exist in such diversity and dynamic range as to overwhelm conventional proteomics technologies. Focused analysis of host protein secretion into the gut lumen and monitoring proteome-level dynamics in stool provides a tractable route toward non-invasively evaluating dietary, microbial, surgical or pharmacological intervention efficacies. This review is intended to guide GI biologists and clinicians through the methods currently used to elucidate host responses in the gut, with a specific focus on mass spectrometry-based shotgun proteomics applied to the study of host protein dynamics within the GI ecosystem.

  11. Host Range Specificity in Verticillium dahliae.

    PubMed

    Bhat, R G; Subbarao, K V

    1999-12-01

    ABSTRACT Verticillium dahliae isolates from artichoke, bell pepper, cabbage, cauliflower, chili pepper, cotton, eggplant, lettuce, mint, potato, strawberry, tomato, and watermelon and V. albo-atrum from alfalfa were evaluated for their pathogenicity on all 14 hosts. One-month-old seedlings were inoculated with a spore suspension of about 10(7) conidia per ml using a root-dip technique and incubated in the greenhouse. Disease incidence and severity, plant height, and root and shoot dry weights were recorded 6 weeks after inoculation. Bell pepper, cabbage, cauliflower, cotton, eggplant, and mint isolates exhibited host specificity and differential pathogenicity on other hosts, whereas isolates from artichoke, lettuce, potato, strawberry, tomato, and watermelon did not. Bell pepper was resistant to all Verticillium isolates except isolates from bell pepper and eggplant. Thus, host specificity exists in some isolates of V. dahliae. The same isolates were characterized for vegetative compatibility groups (VCGs) through complementation of nitrate nonutilizing (nit) mutants. Cabbage and cauliflower isolates did not produce nit mutants. The isolate from cotton belonged to VCG 1; isolates from bell pepper, eggplant, potato, and tomato, to VCG 4; and the remaining isolates, to VCG 2. These isolates were also analyzed using the random amplified polymorphic DNA (RAPD) method. Forty random primers were screened, and eighteen of them amplified DNA from Verticillium. Based on RAPD banding patterns, cabbage and cauliflower isolates formed a unique group, distinct from other V. dahliae and V. albo-atrum groups. Minor genetic variations were observed among V. dahliae isolates from other hosts, regardless of whether they were host specific or not. There was no correlation among pathogenicity, VCGs, and RAPD banding patterns. Even though the isolates belonged to different VCGs, they shared similar RAPD profiles. These results suggest that management of Verticillium wilt in some crops

  12. Archaeal Extrachromosomal Genetic Elements

    PubMed Central

    Wang, Haina; Peng, Nan; Shah, Shiraz A.

    2015-01-01

    SUMMARY Research on archaeal extrachromosomal genetic elements (ECEs) has progressed rapidly in the past decade. To date, over 60 archaeal viruses and 60 plasmids have been isolated. These archaeal viruses exhibit an exceptional diversity in morphology, with a wide array of shapes, such as spindles, rods, filaments, spheres, head-tails, bottles, and droplets, and some of these new viruses have been classified into one order, 10 families, and 16 genera. Investigation of model archaeal viruses has yielded important insights into mechanisms underlining various steps in the viral life cycle, including infection, DNA replication and transcription, and virion egression. Many of these mechanisms are unprecedented for any known bacterial or eukaryal viruses. Studies of plasmids isolated from different archaeal hosts have also revealed a striking diversity in gene content and innovation in replication strategies. Highly divergent replication proteins are identified in both viral and plasmid genomes. Genomic studies of archaeal ECEs have revealed a modular sequence structure in which modules of DNA sequence are exchangeable within, as well as among, plasmid families and probably also between viruses and plasmids. In particular, it has been suggested that ECE-host interactions have shaped the coevolution of ECEs and their archaeal hosts. Furthermore, archaeal hosts have developed defense systems, including the innate restriction-modification (R-M) system and the adaptive CRISPR (clustered regularly interspaced short palindromic repeats) system, to restrict invasive plasmids and viruses. Together, these interactions permit a delicate balance between ECEs and their hosts, which is vitally important for maintaining an innovative gene reservoir carried by ECEs. In conclusion, while research on archaeal ECEs has just started to unravel the molecular biology of these genetic entities and their interactions with archaeal hosts, it is expected to accelerate in the next decade. PMID

  13. Genetic manipulation of Coxiella burnetii.

    PubMed

    Beare, Paul A

    2012-01-01

    Until very recently, Coxiella burnetii was viewed and studied as an obligate intracellular bacterium that relied exclusively on a eucaryotic host cell for growth. Other medically relevant obligate intracellular bacteria reside in the genera Anaplasma, Chlamydia, Ehrlichia, Orientia, and Rickettsia. An obligate intracellular lifestyle presents a significant obstacle to genetic transformation. Procedures that are straightforward with free-living bacteria, such as antibiotic selection and cloning, can be very difficult when growth of transformants is restricted to a host cell. Long-term passage in host cells to expand small transformant populations can further complicate the procedure. Despite these and other obstacles, at least rudimentary systems are currently available for genetic transformation of most obligate intracellular bacterial pathogens. Dramatically aiding the development of new genetic methods for C. burnetii is the recent discovery of a medium that supports host cell-free growth of the organism in liquid, and importantly, on solid media as clonal colonies. The expanded C. burnetii genetics toolbox now includes transposon systems for random mutagenesis and single-copy, site-specific chromosomal gene knock-ins, as well as a shuttle vector for heterologous gene expression and in trans complementation. A reliable method of targeted gene inactivation remains a challenge. Advances in C. burnetii genetic manipulation will allow identification of genes essential for intracellular parasitism and disease pathogenesis, and undoubtedly fuel new interest in this minimally studied bacterial pathogen.

  14. Antagonistic Coevolution of Marine Planktonic Viruses and Their Hosts

    NASA Astrophysics Data System (ADS)

    Martiny, Jennifer B. H.; Riemann, Lasse; Marston, Marcia F.; Middelboe, Mathias

    2014-01-01

    The potential for antagonistic coevolution between marine viruses and their (primarily bacterial) hosts is well documented, but our understanding of the consequences of this rapid evolution is in its infancy. Acquisition of resistance against co-occurring viruses and the subsequent evolution of virus host range in response have implications for bacterial mortality rates as well as for community composition and diversity. Drawing on examples from a range of environments, we consider the potential dynamics, underlying genetic mechanisms and fitness costs, and ecological impacts of virus-host coevolution in marine waters. Given that much of our knowledge is derived from laboratory experiments, we also discuss potential challenges and approaches in scaling up to diverse, complex networks of virus-host interactions. Finally, we note that a variety of novel approaches for characterizing virus-host interactions offer new hope for a mechanistic understanding of antagonistic coevolution in marine plankton.

  15. Antagonistic coevolution of marine planktonic viruses and their hosts.

    PubMed

    Martiny, Jennifer B H; Riemann, Lasse; Marston, Marcia F; Middelboe, Mathias

    2014-01-01

    The potential for antagonistic coevolution between marine viruses and their (primarily bacterial) hosts is well documented, but our understanding of the consequences of this rapid evolution is in its infancy. Acquisition of resistance against co-occurring viruses and the subsequent evolution of virus host range in response have implications for bacterial mortality rates as well as for community composition and diversity. Drawing on examples from a range of environments, we consider the potential dynamics, underlying genetic mechanisms and fitness costs, and ecological impacts of virus-host coevolution in marine waters. Given that much of our knowledge is derived from laboratory experiments, we also discuss potential challenges and approaches in scaling up to diverse, complex networks of virus-host interactions. Finally, we note that a variety of novel approaches for characterizing virus-host interactions offer new hope for a mechanistic understanding of antagonistic coevolution in marine plankton.

  16. Trematode parasites infect or die in snail hosts

    PubMed Central

    King, Kayla C.; Jokela, Jukka; Lively, Curtis M.

    2011-01-01

    The Red Queen hypothesis is based on the assumption that parasites must genetically match their hosts to infect them successfully. If the parasites fail, they are assumed to be killed by the host's immune system. Here, we tested this using sympatric (mostly susceptible) and allopatric (mostly resistant) populations of a freshwater snail and its trematode parasite. We determined whether parasites which do not infect are either killed or passed through the host's digestive tract and remain infectious. Our results show that parasites do not get a second chance: they either infect or are killed by the host. The results suggest strong selection against parasites that are not adapted to local host genotypes. PMID:20961880

  17. Scale insect host ranges are broader in the tropics.

    PubMed

    Hardy, Nate B; Peterson, Daniel A; Normark, Benjamin B

    2015-12-01

    The specificity of the interactions between plants and their consumers varies considerably. The evolutionary and ecological factors underlying this variation are unclear. Several potential explanatory factors vary with latitude, for example plant species richness and the intensity of herbivory. Here, we use comparative phylogenetic methods to test the effect of latitude on host range in scale insects. We find that, on average, scale insects that occur in lower latitudes are more polyphagous. This result is at odds with the general pattern of greater host-plant specificity of insects in the tropics. We propose that this disparity reflects a high cost for host specificity in scale insects, stemming from unusual aspects of scale insect life history, for example, passive wind-driven dispersal. More broadly, the strong evidence for pervasive effects of geography on host range across insect groups stands in stark contrast to the weak evidence for constraints on host range due to genetic trade-offs.

  18. Development of the Digital Engineering Laboratory Computer Network: Host-to-Node/Host-to-Host Protocols.

    DTIC Science & Technology

    1981-12-01

    HOST-TO-HOST PROTOCOLS THESIS AFIT,’GCS/EE/8lD-8 John W. Geist Capt USAF Approved for public release; distribution unlimited. AFIT/GCS/EE/81D-8...DEVELOPMENT OF THE DIGITAL ENGINEERING LABORATORY COMPUTER NETWORK: HOST-TO-NODE/HOST-TO-HOST PROTOCOLS THESIS Presented to the Faculty of the School of...development and operational implementation. I wish to express my appreciation to Dr. Gary B. Lamont, my thesis advisor, for his valued support and

  19. What Can Phages Tell Us about Host-Pathogen Coevolution?

    PubMed Central

    Dennehy, John J.

    2012-01-01

    The outcomes of host-parasite interactions depend on the coevolutionary forces acting upon them, but because every host-parasite relation is enmeshed in a web of biotic and abiotic interactions across a heterogeneous landscape, host-parasite coevolution has proven difficult to study. Simple laboratory phage-bacteria microcosms can ameliorate this difficulty by allowing controlled, well-replicated experiments with a limited number of interactors. Genetic, population, and life history data obtained from these studies permit a closer examination of the fundamental correlates of host-parasite coevolution. In this paper, I describe the results of phage-bacteria coevolutionary studies and their implications for the study of host-parasite coevolution. Recent experimental studies have confirmed phage-host coevolutionary dynamics in the laboratory and have shown that coevolution can increase parasite virulence, specialization, adaptation, and diversity. Genetically, coevolution frequently proceeds in a manner best described by the Gene for Gene model, typified by arms race dynamics, but certain contexts can result in Red Queen dynamics according to the Matching Alleles model. Although some features appear to apply only to phage-bacteria systems, other results are broadly generalizable and apply to all instances of antagonistic coevolution. With laboratory host-parasite coevolutionary studies, we can better understand the perplexing array of interactions that characterize organismal diversity in the wild. PMID:23213618

  20. A parasitic selfish gene that affects host promiscuity.

    PubMed

    Giraldo-Perez, Paulina; Goddard, Matthew R

    2013-11-07

    Selfish genes demonstrate transmission bias and invade sexual populations despite conferring no benefit to their hosts. While the molecular genetics and evolutionary dynamics of selfish genes are reasonably well characterized, their effects on hosts are not. Homing endonuclease genes (HEGs) are one well-studied family of selfish genes that are assumed to be benign. However, we show that carrying HEGs is costly for Saccharomyces cerevisiae, demonstrating that these genetic elements are not necessarily benign but maybe parasitic. We estimate a selective load of approximately 1-2% in 'natural' niches. The second aspect we examine is the ability of HEGs to affect hosts' sexual behaviour. As all selfish genes critically rely on sex for spread, then any selfish gene correlated with increased host sexuality will enjoy a transmission advantage. While classic parasites are known to manipulate host behaviour, we are not aware of any evidence showing a selfish gene is capable of affecting host promiscuity. The data presented here show a selfish element may increase the propensity of its eukaryote host to undergo sex and along with increased rates of non-Mendelian inheritance, this may counterbalance mitotic selective load and promote spread. Demonstration that selfish genes are correlated with increased promiscuity in eukaryotes connects with ideas suggesting that selfish genes promoted the evolution of sex initially.

  1. Gut microbiota, host gene expression, and aging.

    PubMed

    Patrignani, Paola; Tacconelli, Stefania; Bruno, Annalisa

    2014-01-01

    Novel concepts of disease susceptibility and development suggest an important role of gastrointestinal microbiota and microbial pathogens. They can contribute to physiological systems and disease processes, even outside of the gastrointestinal tract. There is increasing evidence that genetics of the host influence and interact with gut microbiota. Moreover, aging-associated oxidative stress may cause morphologic alterations of bacterial cells, thus influencing the aggressive potential and virulence markers of an anaerobic bacterium and finally the type of interaction with the host. At the same time, microbiota may influence host gene expression and it is becoming apparent that it may occur through the regulation of microRNAs. They are short single-stranded noncoding RNAs that regulate posttranscriptional gene expression by affecting mRNA stability and/or translational repression of their target mRNAs. The introduction of -omics approaches (such as metagenomics, metaproteomics, and metatranscriptomics) in microbiota research will certainly advance our knowledge of this area. This will lead to greatly deepen our understanding of the molecular targets in the homeostatic interaction between the gut microbiota and the host and, thereby, promises to reveal new ways to treat diseases and maintain health.

  2. Lack of Host Specialization on Winter Annual Grasses in the Fungal Seed Bank Pathogen Pyrenophora semeniperda

    PubMed Central

    Beckstead, Julie; Meyer, Susan E.; Ishizuka, Toby S.; McEvoy, Kelsey M.; Coleman, Craig E.

    2016-01-01

    Generalist plant pathogens may have wide host ranges, but many exhibit varying degrees of host specialization, with multiple pathogen races that have narrower host ranges. These races are often genetically distinct, with each race causing highest disease incidence on its host of origin. We examined host specialization in the seed pathogen Pyrenophora semeniperda by reciprocally inoculating pathogen strains from Bromus tectorum and from four other winter annual grass weeds (Bromus diandrus, Bromus rubens, Bromus arvensis and Taeniatherum caput-medusae) onto dormant seeds of B. tectorum and each alternate host. We found that host species varied in resistance and pathogen strains varied in aggressiveness, but there was no evidence for host specialization. Most variation in aggressiveness was among strains within populations and was expressed similarly on both hosts, resulting in a positive correlation between strain-level disease incidence on B. tectorum and on the alternate host. In spite of this lack of host specialization, we detected weak but significant population genetic structure as a function of host species using two neutral marker systems that yielded similar results. This genetic structure is most likely due to founder effects, as the pathogen is known to be dispersed with host seeds. All host species were highly susceptible to their own pathogen races. Tolerance to infection (i.e., the ability to germinate even when infected and thereby avoid seed mortality) increased as a function of seed germination rate, which in turn increased as dormancy was lost. Pyrenophora semeniperda apparently does not require host specialization to fully exploit these winter annual grass species, which share many life history features that make them ideal hosts for this pathogen. PMID:26950931

  3. Lack of Host Specialization on Winter Annual Grasses in the Fungal Seed Bank Pathogen Pyrenophora semeniperda.

    PubMed

    Beckstead, Julie; Meyer, Susan E; Ishizuka, Toby S; McEvoy, Kelsey M; Coleman, Craig E

    2016-01-01

    Generalist plant pathogens may have wide host ranges, but many exhibit varying degrees of host specialization, with multiple pathogen races that have narrower host ranges. These races are often genetically distinct, with each race causing highest disease incidence on its host of origin. We examined host specialization in the seed pathogen Pyrenophora semeniperda by reciprocally inoculating pathogen strains from Bromus tectorum and from four other winter annual grass weeds (Bromus diandrus, Bromus rubens, Bromus arvensis and Taeniatherum caput-medusae) onto dormant seeds of B. tectorum and each alternate host. We found that host species varied in resistance and pathogen strains varied in aggressiveness, but there was no evidence for host specialization. Most variation in aggressiveness was among strains within populations and was expressed similarly on both hosts, resulting in a positive correlation between strain-level disease incidence on B. tectorum and on the alternate host. In spite of this lack of host specialization, we detected weak but significant population genetic structure as a function of host species using two neutral marker systems that yielded similar results. This genetic structure is most likely due to founder effects, as the pathogen is known to be dispersed with host seeds. All host species were highly susceptible to their own pathogen races. Tolerance to infection (i.e., the ability to germinate even when infected and thereby avoid seed mortality) increased as a function of seed germination rate, which in turn increased as dormancy was lost. Pyrenophora semeniperda apparently does not require host specialization to fully exploit these winter annual grass species, which share many life history features that make them ideal hosts for this pathogen.

  4. Natural host defense mechanisms.

    PubMed

    Heggers, J P

    1979-10-01

    Severe injury, whether the result of a major accident, a large burn, or a complicated surgical operation, often results in sepsis. Under such conditions both specific and nonspecific host defense systems are affected. The individual facets of major concern are chemotaxis, phagocytosis, intracellular killing, complement depletion, and depression of humoral and cellular mediated immunity. The most profound changes occur in cell-mediated immunity. Within a few hours o injury, the number of circulating T cells becomes depleted, concomitantly thoracic duct lymphocytes are markedly reduced. This change is not only quantitative but functional. The clinical impact of these deficient host defense mechanisms lies in the fact that low virulent organisms may become a lethal threat to the injured patient. Currently, investigators are attempting to reverse thse deficiencies through the use of immunotherapy.

  5. Hosting a Katrina Evacuee.

    NASA Astrophysics Data System (ADS)

    Hoagland, David

    2008-03-01

    No individual or institution anticipated the impact on the academic research community of hurricane Katrina. When Tulane physicist Wayne Reed asked me to host his research group just a day or two after the disaster, with no authorization or understanding of the commitment, I agreed immediately and then pondered implications. Fortunately, colleagues helped in making the commitment real, only the bureaucracy of my public university posing small hindrances. Industry was remarkably generous in providing Reed with significant ``loaner'' equipment, and amazingly, a suite of custom Reed experiments was running within weeks. At the end, the most productive collaborations for Reed seemed not to have been with my group, with its similar research, but to other groups at my institution, particularly the synthetic chemists, who gained access to methods previously unique to Tulane while offering samples previously unique to UMass. Quickly designed projects exploiting this match turned out remarkably productive. Although begun with trepidation, hosting of Reed had huge positive benefits to me and UMass, and I believe, also to Reed and Tulane. Some key lessons for the future: (i) industry has capacity and willingness to help academic research during disruption (ii) commitment of a host institution must be immediate, without a wait for formal approvals or arrangement of special funding -- delay leads only to discouragement, (iii) continuing academic progress of displaced students must come first, and (iv) intellectual synergy rather than overlap should be the basis for seeking a host. Lastly, NSF or other funding agency should consider a program directly addressing the research needs of unexpectedly disrupted academic scientists, and most particularly, graduate students who face greatly extended studies.

  6. Differential genetic variation of chickens and MD vaccine protective efficacy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vaccine protective efficacy is determined by multiple factors including host genetics, the type of vaccine, vaccine dosage, the virulence and dose of challenging viruses, and the interval between vaccination and viral challenge. Studies on human immune responses to vaccinations suggest host genetic...

  7. New constitutive vectors: useful genetic engineering tools for biocatalysis.

    PubMed

    Xu, Youqiang; Tao, Fei; Ma, Cuiqing; Xu, Ping

    2013-04-01

    Constitutive vectors are useful tools for genetic engineering. Two constitutive vectors with high levels of expression and broad host ranges were developed and used in a range of Pseudomonas hosts. The vectors showed superior characteristics compared to the inducible vectors as well as the potential to be used as improved genetic tools for biocatalysis.

  8. Fatty acid-producing hosts

    DOEpatents

    Pfleger, Brian F; Lennen, Rebecca M

    2013-12-31

    Described are hosts for overproducing a fatty acid product such as a fatty acid. The hosts include an exogenous nucleic acid encoding a thioesterase and, optionally, an exogenous nucleic acid encoding an acetyl-CoA carboxylase, wherein an acyl-CoA synthetase in the hosts are functionally delected. The hosts prefereably include the nucleic acid encoding the thioesterase at an intermediate copy number. The hosts are preferably recominantly stable and growth-competent at 37.degree. C. Methods of producing a fatty acid product comprising culturing such hosts at 37.degree. C. are also described.

  9. Identification of a classical mutant in the industrial host Aspergillus niger by systems genetics: LaeA is required for citric acid production and regulates the formation of some secondary metabolites

    SciTech Connect

    Liu, Jing; Arentshorst, Mark; Nair, Deepa; Dai, Ziyu; Baker, Scott E.; Frisvad, Jens; Nielsen, Kristian F.; Punt, Peter J.; Ram, Arthur F.

    2016-01-11

    Rapid acidification of the culture medium by the production of organic acids and the production of acid-induced proteases are key characteristics of the filamentous fungus Aspergillus niger. The D15 mutant of A. niger is non-acidifying mutant and used often for the expression of recombinant proteins in A. niger, because of its reduced production of extracellular proteases under non-acidic conditions. In this study, the D15 mutant is characterized in detail. Strongly reduced levels of citric and oxalic acid were observed in the D15 mutant both in shake flask cultures and in controlled batch cultivations. To identify the mutation in the D15 mutant, we successfully combined high-throughput sequencing (Illumina) with bulk segregant analysis. Because of the lack of a sexual cycle for A. niger, the parasexual cycle was used to generate a pool of segregants. From the 52 single nucleotide polymorphisms (SNPs) between the parental strains, three SNPs were homozygous in the genomic DNA of pool of segregants. These three SNPs mapped to all the right arm of chromosome II, indicating that this region contains the genetic locus affecting the phenotype related to acid production. Of the three SNPs, one mutation resulted in a missense mutation in the gene encoding the A. niger homologue of the A. nidulans methyltransferase gene laeA. Complementation analysis of the original mutant with the laeA gene and targeted disruption of laeA further confirmed that LaeA is involved in citric acid production in A. niger lab (N402) and citric acid production strains (ATCC 11414). Analysis of the secondary metabolite (SM) profile of the laeA mutants indicate that LaeA is required for the production of several SMs (asperrubrol, atromentin and JBIR86), but deletion of laeA also resulted in the presence of SMs (aspernigrin A/B and BMS-192548) that were not detected in the wild-type strain. The levels of ten other SMs were not strongly affected as a result of laeA deletion indicating that only a

  10. Graft-versus-host disease

    MedlinePlus

    GVHD; Bone marrow transplant - graft-versus-host disease; Stem cell transplant - graft-versus-host disease; Allogeneic transplant - ... GVHD may occur after a bone marrow, or stem cell, transplant in which someone receives bone marrow ...

  11. A synthesis of mineralization styles with an integrated genetic model of carbonatite-syenite-hosted REE deposits in the Cenozoic Mianning-Dechang REE metallogenic belt, the eastern Tibetan Plateau, southwestern China

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Hou, Zengqian

    2017-04-01

    factors only occurs along the margins of a craton with a continental root, rather than in modern subduction zones where the lithosphere is relatively thin. U-Pb zircon dating indicates that the Maoniuping, Lizhuang, and Muluozhai alkali igneous complexes in the northern part of the belt formed at 27-22 Ma, whereas the Dalucao complex in the southern part of the belt formed at 12-11 Ma. Biotite and arfvedsonite in Lizhuang and Maoniuping REE deposit have 40Ar/39Ar ages of 30.8 ± 0.4 Ma (MSWD = 0.98) and 27.6 ± 2.0 Ma (MSWD = 0.06), respectively. Biotitaion alteration in syenite and fenitization caused by the relatively amount of carbonatite on syenite and host rocks is the main alteration along the whole belt. Initial Sr (0.7059-0.7079), 143Nd/144Nd (0.5123-0.5127), and 207Pb/204Pb (15.601-15.628) and 208Pb/204Pb (38.422-38.604) isotopic compositions of fluorite, barite, celestite, and calcite in the MD belt are similar to those of the associated syenite and carbonatite. Given the relatively high contents of Cl, F, SO42-, and CO2 in the rocks of the complexes, it is likely that the REEs were transported by these ligands within hydrothermal fluids, and the presence of bastnäsite indicates that the REEs were precipitated as fluorocarbonates. Petrographic, fluid inclusion, and field studies of the ores indicate that bastnäsite and other REE minerals formed during the final stages (<300 °C) of the evolution of magmatic-hydrothermal systems in the belt. The mineralization formed from magmatic and meteoric fluids containing CO2 derived from the decarbonation of carbonatite, as indicated by C-O isotopic values of hydrothermal calcite and bastnäsite (δ13C = -4.8 to -8.7 and δ18O = 5.8 to 12.5‰) and O-H isotopic values of quartz (330 °C) and arfvedsonite (260 °C), which correspond to fluid isotope compositions of δ18O = 0.3-9.8‰ and δD = -70.0 to -152.8‰ in the belt. This study indicates that formation the largest REE deposits are related to voluminous carbonatite

  12. Specific developmental pathways underlie host specificity in the parasitic plant Orobanche

    PubMed Central

    Hiscock, Simon

    2010-01-01

    Parasitic angiosperms are an ecologically and economically important group of plants. However our understanding of the basis for host specificity in these plants is embryonic. Recently we investigated host specificity in the parasitic angiosperm Orobanche minor, and demonstrated that this host generalist parasite comprises genetically defined races that are physiologically adapted to specific hosts. Populations occurring naturally on red clover (Trifolium pratense) and sea carrot (Daucus carota subsp. gummifer) respectively, showed distinct patterns of host specificity at various developmental stages, and a higher fitness on their natural hosts, suggesting these races are locally adapted. Here we discuss the implications of our findings from a broader perspective. We suggest that differences in signal responsiveness and perception by the parasite, as well as qualitative differences in signal production by the host, may elicit host specificity in this parasitic plant. Together with our earlier demonstration that these O. minor races are genetically distinct based on molecular markers, our recent data provide a snapshot of speciation in action, driven by host specificity. Indeed, host specificity may be an underestimated catalyst for speciation in parasitic plants generally. We propose that identifying host specific races using physiological techniques will complement conventional molecular marker-based approaches to provide a framework for delineating evolutionary relationships among cryptic host-specific parasitic plants. PMID:20081361

  13. Comparing mechanisms of host manipulation across host and parasite taxa

    USGS Publications Warehouse

    Lafferty, Kevin D.; Shaw, Jenny C.

    2013-01-01

    Parasites affect host behavior in several ways. They can alter activity, microhabitats or both. For trophically transmitted parasites (the focus of our study), decreased activity might impair the ability of hosts to respond to final-host predators, and increased activity and altered microhabitat choice might increase contact rates between hosts and final-host predators. In an analysis of trophically transmitted parasites, more parasite groups altered activity than altered microhabitat choice. Parasites that infected vertebrates were more likely to impair the host’s reaction to predators, whereas parasites that infected invertebrates were more likely to increase the host’s contact with predators. The site of infection might affect how parasites manipulate their hosts. For instance, parasites in the central nervous system seem particularly suited to manipulating host behavior. Manipulative parasites commonly occupy the body cavity, muscles and central nervous systems of their hosts. Acanthocephalans in the data set differed from other taxa in that they occurred exclusively in the body cavity of invertebrates. In addition, they were more likely to alter microhabitat choice than activity. Parasites in the body cavity (across parasite types) were more likely to be associated with increased host contact with predators. Parasites can manipulate the host through energetic drain, but most parasites use more sophisticated means. For instance, parasites target four physiological systems that shape behavior in both invertebrates and vertebrates: neural, endocrine, neuromodulatory and immunomodulatory. The interconnections between these systems make it difficult to isolate specific mechanisms of host behavioral manipulation.

  14. HUMAN DISPERSAL OF A WIDESPREAD ZOONOSIS IN A DOMESTICATED HOST

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We assessed the evolutionary consequences of swine husbandry for Trichinella spiralis, a food borne parasite that causes severe muscular disease. We find far less genetic diversity in parasites of domesticated pigs than in related parasites of wildlife hosts. In particular, pigs of European origin...

  15. Allergic Host Defenses

    PubMed Central

    Palm, Noah W.; Rosenstein, Rachel K.

    2012-01-01

    Allergies are generally thought to be a detrimental outcome of a mistargeted immune response that evolved to provide immunity to macro-parasites. Here we present arguments to suggest that allergic immunity plays an important role in host defense against noxious environmental substances, including venoms, hematophagous fluids, environmental xenobiotics and irritants. We argue that appropriately targeted allergic reactions are beneficial, although they can become detrimental when excessive. Furthermore, we suggest that allergic hypersensitivity evolved to elicit anticipatory responses and to promote avoidance of suboptimal environments. PMID:22538607

  16. Symbiotic conversations are revealed under genetic interrogation

    PubMed Central

    Ruby, Edward G.

    2013-01-01

    The recent development and application of molecular genetics to the symbionts of invertebrate animal species have advanced our knowledge of the biochemical communication that occurs between the host and its bacterial symbionts. In particular, the ability to manipulate these associations experimentally by introducing genetic variants of the symbionts into naive hosts has allowed the discovery of novel colonization mechanisms and factors. In addition, the role of the symbionts in inducing normal host development has been revealed, and its molecular basis described. In this Review, I discuss many of these developments, focusing on what has been discovered in five well-understood model systems. PMID:18794913

  17. Staphylococcus aureus Host Range and Human-Bovine Host Shift ▿†

    PubMed Central

    Sakwinska, Olga; Giddey, Marlyse; Moreillon, Martine; Morisset, Delphine; Waldvogel, Andreas; Moreillon, Philippe

    2011-01-01

    Staphylococcus aureus is a major agent of bovine mastitis. The concomitant emergence of pig-associated methicillin-resistant S. aureus (MRSA) in human carriage and infection requires a reexamination of the host range and specificity of human- and cow-associated S. aureus strains, something which has not been systematically studied previously. The genetic relatedness of 500 S. aureus isolates from bovine mastitis cases, 57 isolates from nasal carriage of farmers, and 133 isolates from nonfarmers was determined by amplified fragment length polymorphism (AFLP) analysis and spa typing. Multilocus sequence typing (MLST) was conducted on a subset of isolates to match AFLP clusters with MLST clonal complexes (CCs). This data set allowed us to study host range and host specificity and to estimate the extent of bovine-to-human transmission. The genotype compositions of S. aureus isolates from farmers and nonfarmers were very similar, while the mastitis isolates were quite distinct. Overall, transmission was low, but specific genotypes did show increased cow-to-human transmission. Unexpectedly, more than one-third of mastitis isolates belonged to CC8, a lineage which has not been considered to be bovine mastitis associated, but it is well known from human carriage and infection (i.e., USA300). Despite the fact that we did detect some transmission of other genotypes from cows to farmers, no transmission of CC8 isolates to farmers was detected, except for one tentative case. This was despite the close genetic relatedness of mastitis CC8 strains to nonfarmer carriage strains. These results suggest that the emergence of the new bovine-adapted genotype was due to a recent host shift from humans to cows concurrent with a loss of the ability to colonize humans. More broadly, our results indicate that host specificity is a lineage-specific trait that can rapidly evolve. PMID:21742927

  18. Host Specificity of Bacterial Pathogens

    PubMed Central

    Bäumler, Andreas; Fang, Ferric C.

    2013-01-01

    Most pathogens are able to infect multiple hosts but some are highly adapted to a single-host species. A detailed understanding of the basis of host specificity can provide important insights into molecular pathogenesis, the evolution of pathogenic microbes, and the potential for pathogens to cross the species barrier to infect new hosts. Comparative genomics and the development of humanized mouse models have provided important new tools with which to explore the basis of generalism and specialism. This review will examine host specificity of bacterial pathogens with a focus on generalist and specialist serovars of Salmonella enterica. PMID:24296346

  19. Ancient host specificity within a single species of brood parasitic bird

    PubMed Central

    Spottiswoode, Claire N.; Stryjewski, Katherine Faust; Quader, Suhel; Colebrook-Robjent, John F. R.; Sorenson, Michael D.

    2011-01-01

    Parasites that exploit multiple hosts often experience diversifying selection for host-specific adaptations. This can result in multiple strains of host specialists coexisting within a single parasitic species. A long-standing conundrum is how such sympatric host races can be maintained within a single parasitic species in the face of interbreeding among conspecifics specializing on different hosts. Striking examples are seen in certain avian brood parasites such as cuckoos, many of which show host-specific differentiation in traits such as host egg mimicry. Exploiting a Zambian egg collection amassed over several decades and supplemented by recent fieldwork, we show that the brood parasitic Greater Honeyguide Indicator indicator exhibits host-specific differentiation in both egg size and egg shape. Genetic analysis of honeyguide eggs and chicks show that two highly divergent mitochondrial DNA lineages are associated with ground- and tree-nesting hosts, respectively, indicating perfect fidelity to two mutually exclusive sets of host species for millions of years. Despite their age and apparent adaptive diversification, however, these ancient lineages are not cryptic species; a complete lack of differentiation in nuclear genes shows that mating between individuals reared by different hosts is sufficiently frequent to prevent speciation. These results indicate that host specificity is maternally inherited, that host-specific adaptation among conspecifics can be maintained without reproductive isolation, and that host specificity can be remarkably ancient in evolutionary terms. PMID:21949391

  20. Ancient host specificity within a single species of brood parasitic bird.

    PubMed

    Spottiswoode, Claire N; Stryjewski, Katherine Faust; Quader, Suhel; Colebrook-Robjent, John F R; Sorenson, Michael D

    2011-10-25

    Parasites that exploit multiple hosts often experience diversifying selection for host-specific adaptations. This can result in multiple strains of host specialists coexisting within a single parasitic species. A long-standing conundrum is how such sympatric host races can be maintained within a single parasitic species in the face of interbreeding among conspecifics specializing on different hosts. Striking examples are seen in certain avian brood parasites such as cuckoos, many of which show host-specific differentiation in traits such as host egg mimicry. Exploiting a Zambian egg collection amassed over several decades and supplemented by recent fieldwork, we show that the brood parasitic Greater Honeyguide Indicator indicator exhibits host-specific differentiation in both egg size and egg shape. Genetic analysis of honeyguide eggs and chicks show that two highly divergent mitochondrial DNA lineages are associated with ground- and tree-nesting hosts, respectively, indicating perfect fidelity to two mutually exclusive sets of host species for millions of years. Despite their age and apparent adaptive diversification, however, these ancient lineages are not cryptic species; a complete lack of differentiation in nuclear genes shows that mating between individuals reared by different hosts is sufficiently frequent to prevent speciation. These results indicate that host specificity is maternally inherited, that host-specific adaptation among conspecifics can be maintained without reproductive isolation, and that host specificity can be remarkably ancient in evolutionary terms.

  1. Genetic elements of plant viruses as tools for genetic engineering.

    PubMed Central

    Mushegian, A R; Shepherd, R J

    1995-01-01

    Viruses have developed successful strategies for propagation at the expense of their host cells. Efficient gene expression, genome multiplication, and invasion of the host are enabled by virus-encoded genetic elements, many of which are well characterized. Sequences derived from plant DNA and RNA viruses can be used to control expression of other genes in vivo. The main groups of plant virus genetic elements useful in genetic engineering are reviewed, including the signals for DNA-dependent and RNA-dependent RNA synthesis, sequences on the virus mRNAs that enable translational control, and sequences that control processing and intracellular sorting of virus proteins. Use of plant viruses as extrachromosomal expression vectors is also discussed, along with the issue of their stability. PMID:8531885

  2. Testing local host adaptation and phenotypic plasticity in a herbivore when alternative related host plants occur sympatrically.

    PubMed

    Ruiz-Montoya, Lorena; Núñez-Farfán, Juan

    2013-01-01

    Host race formation in phytophagous insects can be an early stage of adaptive speciation. However, the evolution of phenotypic plasticity in host use is another possible outcome. Using a reciprocal transplant experiment we tested the hypothesis of local adaptation in the aphid Brevicoryne brassicae. Aphid genotypes derived from two sympatric host plants, Brassica oleracea and B. campestris, were assessed in order to measure the extent of phenotypic plasticity in morphological and life history traits in relation to the host plants. We obtained an index of phenotypic plasticity for each genotype. Morphological variation of aphids was summarized by principal components analysis. Significant effects of recipient host on morphological variation and life history traits (establishment, age at first reproduction, number of nymphs, and intrinsic growth rate) were detected. We did not detected genotype × host plant interaction; in general the genotypes developed better on B. campestris, independent of the host plant species from which they were collected. Therefore, there was no evidence to suggest local adaptation. Regarding plasticity, significant differences among genotypes in the index of plasticity were detected. Furthermore, significant selection on PC1 (general aphid body size) on B. campestris, and on PC1 and PC2 (body length relative to body size) on B. oleracea was detected. The elevation of the reaction norm of PC1 and the slope of the reaction norm for PC2 (i.e., plasticity) were under directional selection. Thus, host plant species constitute distinct selective environments for B. brassicae. Aphid genotypes expressed different phenotypes in response to the host plant with low or nil fitness costs. Phenotypic plasticity and gene flow limits natural selection for host specialization promoting the maintenance of genetic variation in host exploitation.

  3. Testing Local Host Adaptation and Phenotypic Plasticity in a Herbivore When Alternative Related Host Plants Occur Sympatrically

    PubMed Central

    Ruiz-Montoya, Lorena; Núñez-Farfán, Juan

    2013-01-01

    Host race formation in phytophagous insects can be an early stage of adaptive speciation. However, the evolution of phenotypic plasticity in host use is another possible outcome. Using a reciprocal transplant experiment we tested the hypothesis of local adaptation in the aphid Brevicoryne brassicae. Aphid genotypes derived from two sympatric host plants, Brassica oleracea and B. campestris, were assessed in order to measure the extent of phenotypic plasticity in morphological and life history traits in relation to the host plants. We obtained an index of phenotypic plasticity for each genotype. Morphological variation of aphids was summarized by principal components analysis. Significant effects of recipient host on morphological variation and life history traits (establishment, age at first reproduction, number of nymphs, and intrinsic growth rate) were detected. We did not detected genotype × host plant interaction; in general the genotypes developed better on B. campestris, independent of the host plant species from which they were collected. Therefore, there was no evidence to suggest local adaptation. Regarding plasticity, significant differences among genotypes in the index of plasticity were detected. Furthermore, significant selection on PC1 (general aphid body size) on B. campestris, and on PC1 and PC2 (body length relative to body size) on B. oleracea was detected. The elevation of the reaction norm of PC1 and the slope of the reaction norm for PC2 (i.e., plasticity) were under directional selection. Thus, host plant species constitute distinct selective environments for B. brassicae. Aphid genotypes expressed different phenotypes in response to the host plant with low or nil fitness costs. Phenotypic plasticity and gene flow limits natural selection for host specialization promoting the maintenance of genetic variation in host exploitation. PMID:24265743

  4. Genetics, Epigenetics, and Genomics of Systemic Sclerosis.

    PubMed

    Salazar, Gloria; Mayes, Maureen D

    2015-08-01

    Systemic sclerosis (SSc) is a complex autoimmune disease that occurs in a genetically susceptible host. Genetic studies performed so far reveal that multiple genetic loci contribute to disease susceptibility in SSc. The purpose of this review is to discuss the current knowledge of genetics in SSc by exploring the observational evidence, the different genetic studies, and their modalities as well as the most relevant genes discovered by these. The importance of gene expression variation and the different mechanisms that govern it, including the recently discovered field of epigenetics, are also explored, with an emphasis on microRNA.

  5. Trans-oceanic host dispersal explains high seabird tick diversity on Cape Verde islands.

    PubMed

    Gómez-Díaz, E; Morris-Pocock, J A; González-Solís, J; McCoy, K D

    2012-08-23

    Parasites represent ideal models for unravelling biogeographic patterns and mechanisms of diversification on islands. Both host-mediated dispersal and within-island adaptation can shape parasite island assemblages. In this study, we examined patterns of genetic diversity and structure of Ornithodoros seabird ticks within the Cape Verde Archipelago in relation to their global phylogeography. Contrary to expectations, ticks from multiple, geographically distant clades mixed within the archipelago. Trans-oceanic colonization via host movements probably explains high local tick diversity, contrasting with previous research that suggests little large-scale dispersal in these birds. Although host specificity was not obvious at a global scale, host-associated genetic structure was found within Cape Verde colonies, indicating that post-colonization adaptation to specific hosts probably occurs. These results highlight the role of host metapopulation dynamics in the evolutionary ecology and epidemiology of avian parasites and pathogens.

  6. Expanded host diversity and geographic distribution of hantaviruses in sub-Saharan Africa.

    PubMed

    Kang, Hae Ji; Stanley, William T; Esselstyn, Jacob A; Gu, Se Hun; Yanagihara, Richard

    2014-07-01

    The recent discovery of hantaviruses in shrews and bats in West Africa suggests that other genetically distinct hantaviruses exist in East Africa. Genetic and phylogenetic analyses of newfound hantaviruses, detected in archival tissues from the Geata mouse shrew (Myosorex geata) and Kilimanjaro mouse shrew ( Myosorex zinki) captured in Tanzania, expands the host diversity and geographic distribution of hantaviruses and suggests that ancestral shrews and/or bats may have served as the original mammalian hosts of primordial hantaviruses.

  7. Host range, host specificity and hypothesized host shift events among viruses of lower vertebrates

    PubMed Central

    2011-01-01

    The successful replication of a viral agent in a host is a complex process that often leads to a species specificity of the virus and can make interspecies transmission difficult. Despite this difficulty, natural host switch seems to have been frequent among viruses of lower vertebrates, especially fish viruses, since there are several viruses known to be able to infect a wide range of species. In the present review we will focus on well documented reports of broad host range, variations in host specificity, and host shift events hypothesized for viruses within the genera Ranavirus, Novirhabdovirus, Betanodavirus, Isavirus, and some herpesvirus. PMID:21592358

  8. Transmission dynamics of two strains of Schistosoma mansoni utilizing novel intermediate and definitive hosts.

    PubMed

    Jones-Nelson, Omari; Thiele, Elizabeth A; Minchella, Dennis J

    2011-09-01

    The intimate host-parasite relationship mandates adaptation to the genetic and phenotypic variability of their counterparts. Here, inbred and outcrossed strains of Schistosoma mansoni were challenged with "local" and "novel" intermediate and definitive hosts to examine effects of genetic variability and novelty on infection success and dynamics. Genetically distinct lines of Biomphalaria glabrata intermediate hosts exposed to inbred and outcrossed S. mansoni larvae were assessed for differences in both snail and parasite life-history parameters. Cercariae from each parasite-snail treatment were used to infect "local" and "novel" Mus musculus definitive hosts to assess parasite infectivity and fitness. Outcrossed parasites significantly reduced snail growth, were more productive, and induced greater host mortality than inbred parasites. Mouse strain did not influence parasite infectivity or reproduction, but parasite and snail host genetic background did, affecting both sex-specific infectivity and parasite productivity. Overall, genetic background of S. mansoni and its intermediate snail host altered life history traits and transmission dynamics of the parasite throughout its life cycle.

  9. Avian host defense peptides.

    PubMed

    Cuperus, Tryntsje; Coorens, Maarten; van Dijk, Albert; Haagsman, Henk P

    2013-11-01

    Host defense peptides (HDPs) are important effector molecules of the innate immune system of vertebrates. These antimicrobial peptides are also present in invertebrates, plants and fungi. HDPs display broad-spectrum antimicrobial activities and fulfill an important role in the first line of defense of many organisms. It is becoming increasingly clear that in the animal kingdom the functions of HDPs are not confined to direct antimicrobial actions. Research in mammals has indicated that HDPs have many immunomodulatory functions and are also involved in other physiological processes ranging from development to wound healing. During the past five years our knowledge about avian HDPs has increased considerably. This review addresses our current knowledge on the evolution, regulation and biological functions of HDPs of birds.

  10. Host density drives the postglacial migration of the tree parasite, Epifagus virginiana

    PubMed Central

    Tsai, Yi-Hsin Erica; Manos, Paul S.

    2010-01-01

    To survive changes in climate, successful species shift their geographic ranges to remain in suitable habitats. For parasites and other highly specialized species, distributional changes not only are dictated by climate but can also be engineered by their hosts. The extent of host control on parasite range expansion is revealed through comparisons of host and parasite migration and demographic histories. However, understanding the codistributional history of entire forest communities is complicated by challenges in synthesizing datasets from multiple interacting species of differing datatypes. Here we integrate genetic and fossil pollen datasets from a host–parasite pair; specifically, the population structure of the parasitic plant (Epifagus virginiana) was compared with both its host (Fagus grandifolia) genetic patterns and abundance data from the paleopollen record of the last 21,000 y. Through tests of phylogeographic structure and spatial linear regression models we find, surprisingly, host range changes had little effect on the parasite's range expansion and instead host density is the main driver of parasite spread. Unlike other symbionts that have been used as proxies to track their host's movements, this parasite's migration routes are incongruent with the host and instead reflect the greater importance of host density in this community's assembly. Furthermore, these results confirm predictions of disease ecological models regarding the role of host density in the spread of pathogens. Due to host density constraints, highly specialized species may have low migration capacities and long lag times before colonization of new areas. PMID:20841421

  11. Host-associated differentiation in a pecan and water hickory Aphidomorpha community

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Host-Associated Differentiation (HAD) is the formation of genetically distinct, host-associated populations created and maintained by ecologically-mediated reproductive isolation. HAD potentially accounts for a high level of species diversity in parasites, including herbivorous insects. While case s...

  12. Geographic pattern of host-associated differentiation in Pseudatomoscelis seriatus (Reuter)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Host-associated differentiation (HAD) is the presence of genetically divergent, host-associated populations, and a phenomenon thought to promote diversity in parasitic organisms. HAD in phytophagous insects has mostly been documented in specialist, univoltine insects inhabiting feral ecosystems or i...

  13. Indication for Co-evolution of Lactobacillus johnsonii with its hosts

    PubMed Central

    2012-01-01

    Background The intestinal microbiota, composed of complex bacterial populations, is host-specific and affected by environmental factors as well as host genetics. One important bacterial group is the lactic acid bacteria (LAB), which include many health-promoting strains. Here, we studied the genetic variation within a potentially probiotic LAB species, Lactobacillus johnsonii, isolated from various hosts. Results A wide survey of 104 fecal samples was carried out for the isolation of L. johnsonii. As part of the isolation procedure, terminal restriction fragment length polymorphism (tRFLP) was performed to identify L. johnsonii within a selected narrow spectrum of fecal LAB. The tRFLP results showed host specificity of two bacterial species, the Enterococcus faecium species cluster and Lactobacillus intestinalis, to different host taxonomic groups while the appearance of L. johnsonii and E. faecalis was not correlated with any taxonomic group. The survey ultimately resulted in the isolation of L. johnsonii from few host species. The genetic variation among the 47 L. johnsonii strains isolated from the various hosts was analyzed based on variation at simple sequence repeats (SSR) loci and multi-locus sequence typing (MLST) of conserved hypothetical genes. The genetic relationships among the strains inferred by each of the methods were similar, revealing three different clusters of L. johnsonii strains, each cluster consisting of strains from a different host, i.e. chickens, humans or mice. Conclusions Our typing results support phylogenetic separation of L. johnsonii strains isolated from different animal hosts, suggesting specificity of L. johnsonii strains to their hosts. Taken together with the tRFLP results, that indicated the association of specific LAB species with the host taxonomy, our study supports co-evolution of the host and its intestinal lactic acid bacteria. PMID:22827843

  14. Genetic counseling

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000510.htm Genetic counseling To use the sharing features on this ... cystic fibrosis or Down syndrome. Who May Want Genetic Counseling? It is up to you whether or ...

  15. Genetic Disorders

    MedlinePlus

    ... This can cause a medical condition called a genetic disorder. You can inherit a gene mutation from ... during your lifetime. There are three types of genetic disorders: Single-gene disorders, where a mutation affects ...

  16. Genes for host-plant selection in Drosophila.

    PubMed

    Matsuo, Takashi

    2008-01-01

    Interactions between herbivorous insects and their host plants are rich in diversity. How such interactions evolved has been a central issue in ecology. A series of analyses on an example of host-plant adaptation in a Drosophila species suggest that neurogenetics can be a powerful tool for understanding how insects' ability to select a specific host plant has evolved. Drosophila sechellia is a specialist species that exclusively reproduces on the ripe fruit of Morinda citrifolia, which is toxic to other Drosophila species, including D. melanogaster and D. simulans, which are phylogenetically close to D. sechellia. Genetic analyses have revealed that multiple loci are involved in the physiological and behavioral adaptations of D. sechellia to the Morinda fruit. The behavioral adaptation includes the loss of avoidance of the host toxin and the enhanced sensitivity to the host odor. Two odorant-binding protein genes, Obp57d and Obp57e, are involved in the perception of the host toxin. D. sechellia has lost several putative bitter-taste receptor genes, which might also be involved in the loss of avoidance of the host toxin. The available genetic data support an evolutionary scenario, in which the shift in the host-plant selection was not achieved by the acquisition of novel abilities, but by the loss of already existing abilities. It is also suggested that the size of chemosensory gene families has a potential to be an index of complexity in insect-environment interaction, providing an opportunity to reexamine the longstanding "specialization as an evolutionary dead end" hypothesis.

  17. Genetic modification and genetic determinism.

    PubMed

    Resnik, David B; Vorhaus, Daniel B

    2006-06-26

    In this article we examine four objections to the genetic modification of human beings: the freedom argument, the giftedness argument, the authenticity argument, and the uniqueness argument. We then demonstrate that each of these arguments against genetic modification assumes a strong version of genetic determinism. Since these strong deterministic assumptions are false, the arguments against genetic modification, which assume and depend upon these assumptions, are therefore unsound. Serious discussion of the morality of genetic modification, and the development of sound science policy, should be driven by arguments that address the actual consequences of genetic modification for individuals and society, not by ones propped up by false or misleading biological assumptions.

  18. Genetic modification and genetic determinism

    PubMed Central

    Resnik, David B; Vorhaus, Daniel B

    2006-01-01

    In this article we examine four objections to the genetic modification of human beings: the freedom argument, the giftedness argument, the authenticity argument, and the uniqueness argument. We then demonstrate that each of these arguments against genetic modification assumes a strong version of genetic determinism. Since these strong deterministic assumptions are false, the arguments against genetic modification, which assume and depend upon these assumptions, are therefore unsound. Serious discussion of the morality of genetic modification, and the development of sound science policy, should be driven by arguments that address the actual consequences of genetic modification for individuals and society, not by ones propped up by false or misleading biological assumptions. PMID:16800884

  19. Multiple host shifts by the emerging honeybee parasite, Varroa jacobsoni.

    PubMed

    Roberts, J M K; Anderson, D L; Tay, W T

    2015-05-01

    Host shifts are a key mechanism of parasite evolution and responsible for the emergence of many economically important pathogens. Varroa destructor has been a major factor in global honeybee (Apis mellifera) declines since shifting hosts from the Asian honeybee (Apis cerana) > 50 years ago. Until recently, only two haplotypes of V. destructor (Korea and Japan) had successfully host shifted to A. mellifera. In 2008, the sister species V. jacobsoni was found for the first time parasitizing A. mellifera in Papua New Guinea (PNG). This recent host shift presents a serious threat to world apiculture but also provides the opportunity to examine host shifting in this system. We used 12 microsatellites to compare genetic variation of V. jacobsoni on A. mellifera in PNG with mites on A. cerana in both PNG and surrounding regions. We identified two distinct lineages of V. jacobsoni reproducing on A. mellifera in PNG. Our analysis indicated independent host shift events have occurred through small numbers of mites shifting from local A. cerana populations. Additional lineages were found in the neighbouring Papua and Solomon Islands that had partially host shifted to A. mellifera, that is producing immature offspring on drone brood only. These mites were likely in transition to full colonization of A. mellifera. Significant population structure between mites on the different hosts suggested host shifted V. jacobsoni populations may not still reproduce on A. cerana, although limited gene flow may exist. Our studies provide further insight into parasite host shift evolution and help characterize this new Varroa mite threat to A. mellifera worldwide.

  20. Imaging Genetics

    ERIC Educational Resources Information Center

    Munoz, Karen E.; Hyde, Luke W.; Hariri, Ahmad R.

    2009-01-01

    Imaging genetics is an experimental strategy that integrates molecular genetics and neuroimaging technology to examine biological mechanisms that mediate differences in behavior and the risks for psychiatric disorder. The basic principles in imaging genetics and the development of the field are discussed.

  1. Hitchhiking of host biology by beneficial symbionts enhances transmission

    PubMed Central

    Ott, Brittany M.; Cruciger, Michael; Dacks, Andrew M.; Rio, Rita V. M.

    2014-01-01

    Transmission plays a key role in the evolution of symbiosis. Mixed mode transmission combines horizontal and vertical mechanisms for symbiont acquisition. However, features that enable mixed transmission are poorly understood. Here, we determine the mechanistic basis for the recruitment of the beneficial bacterium, Aeromonas veronii by the leech, Hirudo verbana. We demonstrate that host mucosal secretions complement imperfect symbiont vertical transmission. First, we show that the A. veronii population within secretions originates from the host digestive tract and proliferates synchronously with shedding frequency, demonstrating the coupling of partner biology. Furthermore, leeches are attracted to these castings with oral contact proving sufficient for symbiont transmission. Leech attraction to mucus is not affected by the symbiont state of either the host or mucus, suggesting that A. veronii exploits preexisting host behavior and physiological traits. A dual transmission mode, integrating multiple layers of host contributions, may prove evolutionarily advantageous for a wide range of symbioses. Using such a strategy, host infection is ensured, while also providing access to a higher genetic diversity of symbionts. Countless host-associated microbes exhibit mixed mode transmission, supporting the use of the leech symbiosis as a model for enhancing our understanding of the specificity, establishment and persistence of microbiotas. PMID:25059557

  2. Reservoir Host Immune Responses to Emerging Zoonotic Viruses

    PubMed Central

    Mandl, Judith N.; Ahmed, Rafi; Barreiro, Luis B.; Daszak, Peter; Epstein, Jonathan H.; Virgin, Herbert W.; Feinberg, Mark B.

    2015-01-01

    Zoonotic viruses, such as HIV, Ebola virus, coronaviruses, influenza A viruses, hantaviruses, or henipaviruses, can result in profound pathology in humans. In contrast, populations of the reservoir hosts of zoonotic pathogens often appear to tolerate these infections with little evidence of disease. Why are viruses more dangerous in one species than another? Immunological studies investigating quant