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Sample records for 2n gamete formation

  1. Determination of n+1 gamete transmission rate of trisomics and location of gene controlling 2n gamete formation in Chinese cabbage (Brassica rapa).

    PubMed

    Zhang, Cheng-He; Li, Xiao-Feng; Shen, Shu-Xing; Yuan, He; Xuan, Shu-Xin

    2009-01-01

    A set of trisomics of Chinese cabbage was used for determining the n+1 gamete transmission rate and locating the gene controlling 2n gamete formation on the corresponding chromosome. The results showed that the transmission rates of extra chromosomes in different trisomics varied from 0% to 15.38% by male gametes and from 0% to 17.39% by female gametes. Of the nine F(2) populations derived from the hybridizations between each trisomic and Bp058 (2n gamete material), only Tri-4xBp058 showed that the segregation ratio of plants without 2n gamete formation to plants with 2n gamete formation was 10.38:1, which fitted the expected segregation ratio of the trisomics (AAa) based on the 7.37% of n+1 gamete transmission through female and 5.88% through male. In other populations the segregation ratios varied from 2.48:1 to 3.72:1, which fitted the expected 3:1 segregation ratio of the bisomics (Aa). These results suggested that the gene controlling 2n gamete formation in Chinese cabbage Bp058 was located on chromosome 4. Further trisomic analysis based on the chromosome segregation and the incomplete stochastic chromatid segregation indicated that the gene locus was tightly linked to the centromere.

  2. Exploitation of induced 2n-gametes for plant breeding.

    PubMed

    Younis, Adnan; Hwang, Yoon-Jung; Lim, Ki-Byung

    2014-02-01

    Unreduced gamete formation derived via abnormal meiotic cell division is an important approach to polyploidy breeding. This process is considered the main driving force in spontaneous polyploids formation in nature, but the potential application of these gametes to plant breeding has not been fully exploited. An effective mechanism for their artificial induction is needed to attain greater genetic variation and enable efficient use of unreduced gametes in breeding programs. Different approaches have been employed for 2n-pollen production including interspecific hybridization, manipulation of environmental factors and treatment with nitrous oxide, trifluralin, colchicine, oryzalin and other chemicals. These chemicals can act as a stimulus to produce viable 2n pollen; however, their exact mode of action, optimum concentration and developmental stages are still not known. Identification of efficient methods of inducing 2n-gamete formation will help increase pollen germination of sterile interspecific hybrids for inter-genomic recombination and introgression breeding to develop new polyploid cultivars and increase heterozygosity among plant populations. Additionally, the application of genomic tools and identification and isolation of genes and mechanisms involved in the induction of 2n-gamete will enable increased exploitation in different plant species, which will open new avenues for plant breeding. PMID:24311154

  3. Gamete formation without meiosis in Arabidopsis.

    PubMed

    Ravi, Maruthachalam; Marimuthu, Mohan P A; Siddiqi, Imran

    2008-02-28

    Apomixis, the formation of asexual seeds in plants, leads to populations that are genetically uniform maternal clones. The transfer of apomixis to crop plants holds great promise in plant breeding for fixation of heterozygosity and hybrid vigour because it would allow the propagation of hybrids over successive generations. Apomixis involves the production of unreduced (diploid) female gametes that retain the genotype of the parent plant (apomeiosis), followed by parthenogenetic development of the egg cell into an embryo and the formation of functional endosperm. The molecular mechanisms underlying apomixis are unknown. Here we show that mutation of the Arabidopsis gene DYAD/SWITCH1 (SWI1), a regulator of meiotic chromosome organization, leads to apomeiosis. We found that most fertile ovules in dyad plants form seeds that are triploid and that arise from the fertilization of an unreduced female gamete by a haploid male gamete. The unreduced female gametes fully retain parental heterozygosity across the genome, which is characteristic of apomeiosis. Our results show that the alteration of a single gene in a sexual plant can bring about functional apomeiosis, a major component of apomixis.

  4. The effect of 2n gametes on sex ratios in Actinidia.

    PubMed

    Seal, Alan G; Ferguson, A Ross; de Silva, H Nihal; Zhang, Jing-Li

    2012-09-01

    Sex can sometimes lead to complications. In some crops, 2n gametes have been exploited by plant breeders to transfer genetic variation between taxa of different ploidy levels. However, their role and use in dioecious genera have received relatively little attention. In the dioecious genus Actinidia (kiwifruit), seedling populations usually segregate equally for females and males as sex is determined by an XX female/XY male system. While fertilization involving 2n egg cells is not expected to affect the sex ratios of progenies, fertilization involving 2n pollen is likely to produce progenies with excess males. The extent of sex ratio distortion will depend on the relative contributions of first and second division restitution, and the frequency and location of cross-overs in meiosis. In this study, seedlings recovered from crosses between females of hexaploid Actinidia deliciosa and males of two diploid species, Actinidia chinensis and Actinidia eriantha, included a proportion of pentaploid hybrids presumably derived from fertilization involving 2n pollen. Most of these pentaploids were male, and a proportion of them were likely to be carrying two Y chromosomes. If used as parents in further crosses, males with multiple Y chromosomes are likely to cause distorted sex ratios in their immediate progenies. In dioecious genera such as Actinidia, the effects on sex ratios of different mechanisms of ploidy change need to be taken into account when considering the evolution of polyploidy and the design of breeding strategies involving ploidy manipulation.

  5. Meiotic aberrations during 2n pollen formation in Begonia.

    PubMed

    Dewitte, A; Eeckhaut, T; Van Huylenbroeck, J; Van Bockstaele, E

    2010-02-01

    Unreduced gametes are the driving force for the polyploidization of plants in nature, and are also an important tool for ploidy breeding. The final heterozygosity of a 2n pollen grain depends on the cytological mechanism behind 2n pollen formation. In this study, chromosome pairing and chromosome segregation during the microsporogenesis of seven Begonia genotypes were analysed using fluorescent chromosome staining on (squashed) pollen mother cells. Among the seven genotypes, five genotypes produce 2n pollen (B. 'Bubbles', B. 'Florence Rita', B. 'Orococo', B. 'Tamo' and B276) and two genotypes produce only normal n pollen (B. fischeri and B243). All 2n pollen producers showed a mechanism equivalent to first division restitution (FDR), in which chromosomes did not segregate during meiosis I but only during meiosis II. This FDR was the result of (a) an irregular chromosome pairing in B. 'Tamo', (b) stickiness of chromosomes associated with numerous chromosome bridges in B. 'Florence Rita' and B276, and (c) a combination of irregular chromosome pairing and stickiness of chromosomes in B. 'Bubbles'. The exact mechanism of the nuclear restitution in B. 'Orococo' could not be determined. Other mechanisms, such as early asymmetric cytokinesis, omission of meiosis II, parallel or tripolar spindle formation, were rather uncommon. Unpaired chromosomes (univalents) were observed in all genotypes, but they had moved to one of the poles by the end of anaphase I or II. Only B. 'Tamo' formed a high number of micronuclei. Consequently, this genotype formed a large number of malformed pollen. Obviously, chromosome behaviour during meiosis in Begonia is very dynamic, which may have important consequences for chromosome evolution and biodiversity within the genus.

  6. Complete asynapsis resulting in 2n pollen formation in Paspalum jesuiticum Parodi (Poaceae).

    PubMed

    Bernardo Filho, R A; Santos, A C C; Souza, F H D; Valls, J F M; Pagliarini, M S

    2014-01-01

    Cytological investigation revealed complete asynapsis during microsporogenesis in 2 wild accessions of Paspalum jesuiticum collected in distinct Brazilian regions. Both accessions were hexaploid (2n = 6x = 60) and 60 univalents could be counted at diakinesis. In this phase, the majority of meiocytes exhibited univalents with both chromatids. After alignment at the metaphase plate, the chromatids segregated to the poles. Only 1 meiotic division (equational) occurred, and after cytokinesis, a dyad with 2n microspores was formed. The genetic constitution of the 2n gametes was equivalent to that of first division restitution (FDR). Since recombination did not occur, 100% transmission of parental heterozygosity could be expected from the FDR 2n gametes. The meiotic behavior of both accessions suggested that they resulted from a recent natural hybridization event. The potential use of the 2n gametes in Paspalum breeding programs has been discussed. PMID:24535851

  7. Polyploidization mechanisms: temperature environment can induce diploid gamete formation in Rosa sp.

    PubMed

    Pécrix, Yann; Rallo, Géraldine; Folzer, Hélène; Cigna, Mireille; Gudin, Serge; Le Bris, Manuel

    2011-06-01

    Polyploidy is an important evolutionary phenomenon but the mechanisms by which polyploidy arises still remain underexplored. There may be an environmental component to polyploidization. This study aimed to clarify how temperature may promote diploid gamete formation considered an essential element for sexual polyploidization. First of all, a detailed cytological analysis of microsporogenesis and microgametogenesis was performed to target precisely the key developmental stages which are the most sensitive to temperature. Then, heat-induced modifications in sporad and pollen characteristics were analysed through an exposition of high temperature gradient. Rosa plants are sensitive to high temperatures with a developmental sensitivity window limited to meiosis. Moreover, the range of efficient temperatures is actually narrow. 36 °C at early meiosis led to a decrease in pollen viability, pollen ectexine defects but especially the appearance of numerous diploid pollen grains. They resulted from dyads or triads mainly formed following heat-induced spindle misorientations in telophase II. A high temperature environment has the potential to increase gamete ploidy level. The high frequencies of diplogametes obtained at some extreme temperatures support the hypothesis that polyploidization events could have occurred in adverse conditions and suggest polyploidization facilitating in a global change context. PMID:21398431

  8. Cell fusion as the formation mechanism of unreduced gametes in the gynogenetic diploid hybrid fish.

    PubMed

    Wang, Jing; Liu, Qingfeng; Luo, Kaikun; Chen, Xuan; Xiao, Jun; Zhang, Chun; Tao, Min; Zhao, Rurong; Liu, Shaojun

    2016-01-01

    The gynogenetic diploid hybrid clone line (GDH) derived from red crucian carp (♀ RCC) × common carp (♂ CC) possesses the unusual reproductive trait of producing unreduced diploid eggs. To identify the mechanism underlying this phenomenon, we examined the structure, in vivo developmental process and in vitro dynamic development of the GDH gonad. In summary, compared with RCC and CC, GDH showed certain special straits. First, a high frequency (84.7%) of germ cell fusion occurred in gonadal tissue culture in vitro as observed by time-lapse microscopy. Second, microstructural and ultrastructural observation showed numerous binucleated and multinucleated germ cells in the gonad, providing evidence of germ cell fusion in vivo. By contrast, in the diploid RCC and CC ovaries, neither cell fusion nor multinucleated cells were observed during the development of gonads. Third, the ovary of GDH remained at stage I for 10 months, whereas those of RCC and CC remained at that stage for 2 months, indicating that the GDH germ cells underwent abnormal development before meiosis. This report is the first to demonstrate that cell fusion facilitates the formation of unreduced gametes in vertebrates, which is a valuable finding for both evolutionary biology and reproductive biology. PMID:27530321

  9. Cell fusion as the formation mechanism of unreduced gametes in the gynogenetic diploid hybrid fish

    PubMed Central

    Wang, Jing; Liu, Qingfeng; Luo, Kaikun; Chen, Xuan; Xiao, Jun; Zhang, Chun; Tao, Min; Zhao, Rurong; Liu, Shaojun

    2016-01-01

    The gynogenetic diploid hybrid clone line (GDH) derived from red crucian carp (♀ RCC) × common carp (♂ CC) possesses the unusual reproductive trait of producing unreduced diploid eggs. To identify the mechanism underlying this phenomenon, we examined the structure, in vivo developmental process and in vitro dynamic development of the GDH gonad. In summary, compared with RCC and CC, GDH showed certain special straits. First, a high frequency (84.7%) of germ cell fusion occurred in gonadal tissue culture in vitro as observed by time-lapse microscopy. Second, microstructural and ultrastructural observation showed numerous binucleated and multinucleated germ cells in the gonad, providing evidence of germ cell fusion in vivo. By contrast, in the diploid RCC and CC ovaries, neither cell fusion nor multinucleated cells were observed during the development of gonads. Third, the ovary of GDH remained at stage I for 10 months, whereas those of RCC and CC remained at that stage for 2 months, indicating that the GDH germ cells underwent abnormal development before meiosis. This report is the first to demonstrate that cell fusion facilitates the formation of unreduced gametes in vertebrates, which is a valuable finding for both evolutionary biology and reproductive biology. PMID:27530321

  10. Cytomictic Anomalous Male Meiosis and 2n Pollen Grain Formation in Mertensia echioides Benth. (Boraginaceae) from Kashmir Himalaya

    PubMed Central

    Malik, Reyaz Ahmad; Gupta, Raghbir Chand; Kumari, Santosh; Malik, Akhtar Hussain

    2014-01-01

    Presently Mertensia echioides Benth. (Boraginaceae) collected from Kashmir Himalaya, India, is cytologically analyzed for the first time revealing 2n = 2x = 24 (diploid). Interestingly we found 4.3–6.2% syncytic meiocytes/PMCs with 2n = 4x = 48 (tetraploid) in addition to normal meiocytes (2n = 24) during male meiosis. These comparatively larger PMCs (pollen mother cells) lead to the formation of fertile giant 2n pollen grains. A frequency of 6.4–13.3% PMCs shows transfer of chromatin material at prophase-I and, therefore, results in aneuploid meiocytes. Whole chromatin transfer by the process of cytomixis could also have led to the formation of tetraploid cells. Translocation heterozygosity is also evident in the form of multivalents in 12–17% diploid (2x) meiocytes at diakinesis and metaphase-I and is reported for the first time in this species. The syncytes formed depict open chain hexavalent and quadrivalent formation in the three populations with different frequencies. Moreover chromatin stickiness at metaphase-I is observed in 45% of PMCs in population-1 (P-1). Syncyte or unreduced PMC formation leading to unreduced fertile gametes is here speculated to act as a possible way out for infraspecific polyploidization in the species. PMID:25544950

  11. Cytomictic anomalous male meiosis and 2n pollen grain formation in Mertensia echioides Benth. (Boraginaceae) from Kashmir Himalaya.

    PubMed

    Malik, Reyaz Ahmad; Gupta, Raghbir Chand; Kumari, Santosh; Malik, Akhtar Hussain

    2014-01-01

    Presently Mertensia echioides Benth. (Boraginaceae) collected from Kashmir Himalaya, India, is cytologically analyzed for the first time revealing 2n = 2x = 24 (diploid). Interestingly we found 4.3-6.2% syncytic meiocytes/PMCs with 2n = 4x = 48 (tetraploid) in addition to normal meiocytes (2n = 24) during male meiosis. These comparatively larger PMCs (pollen mother cells) lead to the formation of fertile giant 2n pollen grains. A frequency of 6.4-13.3% PMCs shows transfer of chromatin material at prophase-I and, therefore, results in aneuploid meiocytes. Whole chromatin transfer by the process of cytomixis could also have led to the formation of tetraploid cells. Translocation heterozygosity is also evident in the form of multivalents in 12-17% diploid (2x) meiocytes at diakinesis and metaphase-I and is reported for the first time in this species. The syncytes formed depict open chain hexavalent and quadrivalent formation in the three populations with different frequencies. Moreover chromatin stickiness at metaphase-I is observed in 45% of PMCs in population-1 (P-1). Syncyte or unreduced PMC formation leading to unreduced fertile gametes is here speculated to act as a possible way out for infraspecific polyploidization in the species. PMID:25544950

  12. Gamete Dialogs in Green Lineages.

    PubMed

    Mori, Toshiyuki; Kawai-Toyooka, Hiroko; Igawa, Tomoko; Nozaki, Hisayoshi

    2015-10-01

    Gamete fusion is a core process of sexual reproduction and, in both plants and animals, different sex gametes fuse within species. Although most of the molecular factors involved in gamete interaction are still unknown in various sex-possessing eukaryotes, reports of such factors in algae and land plants have been increasing in the past decade. In particular, knowledge of gamete interaction in flowering plants and green algae has increased since the identification of the conserved gamete fusion factor generative cell specific 1/hapless 2 (GCS1/HAP2). GCS1 was first identified as a pollen generative cell-specific transmembrane protein in the lily (Lilium longiflorum), and was then shown to function not only in flowering plant gamete fusion but also in various eukaryotes, including unicellular protists and metazoans. In addition, although initially restricted to Chlamydomonas, knowledge of gamete attachment in flowering plants was also acquired. This review focuses on recent progress in the study of gamete interaction in volvocine green algae and flowering plants and discusses conserved mechanisms of gamete recognition, attachment, and fusion leading to zygote formation.

  13. Cytological, molecular mechanisms and temperature stress regulating production of diploid male gametes in Dianthus caryophyllus L.

    PubMed

    Zhou, Xuhong; Mo, Xijun; Gui, Min; Wu, Xuewei; Jiang, Yalian; Ma, Lulin; Shi, Ziming; Luo, Ying; Tang, Wenru

    2015-12-01

    In plant evolution, because of its key role in sexual polyploidization or whole genome duplication events, diploid gamete formation is considered as an important component in diversification and speciation. Environmental stress often triggers unreduced gamete production. However, the molecular, cellular mechanisms and adverse temperature regulating diplogamete production in carnation remain poorly understood. Here, we investigate the cytological basis for 2n male gamete formation and describe the isolation and characterization of the first gene, DcPS1 (Dianthus Caryophyllus Parallel Spindle 1). In addition, we analyze influence of temperature stress on diploid gamete formation and transcript levels of DcPS1. Cytological evidence indicated that 2n male gamete formation is attributable to abnormal spindle orientation at male meiosis II. DcPS1 protein is conserved throughout the plant kingdom and carries domains suggestive of a regulatory function. DcPS1 expression analysis show DcPS1 gene probably have a role in 2n pollen formation. Unreduced pollen formation in various cultivation was sensitive to high or low temperature which was probably regulated by the level of DcPS1 transcripts. In a broader perspective, these findings can have potential applications in fundamental polyploidization research and plant breeding programs.

  14. The specification and global reprogramming of histone epigenetic marks during gamete formation and early embryo development in C. elegans.

    PubMed

    Samson, Mark; Jow, Margaret M; Wong, Catherine C L; Fitzpatrick, Colin; Aslanian, Aaron; Saucedo, Israel; Estrada, Rodrigo; Ito, Takashi; Park, Sung-kyu Robin; Yates, John R; Chu, Diana S

    2014-10-01

    In addition to the DNA contributed by sperm and oocytes, embryos receive parent-specific epigenetic information that can include histone variants, histone post-translational modifications (PTMs), and DNA methylation. However, a global view of how such marks are erased or retained during gamete formation and reprogrammed after fertilization is lacking. To focus on features conveyed by histones, we conducted a large-scale proteomic identification of histone variants and PTMs in sperm and mixed-stage embryo chromatin from C. elegans, a species that lacks conserved DNA methylation pathways. The fate of these histone marks was then tracked using immunostaining. Proteomic analysis found that sperm harbor ∼2.4 fold lower levels of histone PTMs than embryos and revealed differences in classes of PTMs between sperm and embryos. Sperm chromatin repackaging involves the incorporation of the sperm-specific histone H2A variant HTAS-1, a widespread erasure of histone acetylation, and the retention of histone methylation at sites that mark the transcriptional history of chromatin domains during spermatogenesis. After fertilization, we show HTAS-1 and 6 histone PTM marks distinguish sperm and oocyte chromatin in the new embryo and characterize distinct paternal and maternal histone remodeling events during the oocyte-to-embryo transition. These include the exchange of histone H2A that is marked by ubiquitination, retention of HTAS-1, removal of the H2A variant HTZ-1, and differential reprogramming of histone PTMs. This work identifies novel and conserved features of paternal chromatin that are specified during spermatogenesis and processed in the embryo. Furthermore, our results show that different species, even those with diverged DNA packaging and imprinting strategies, use conserved histone modification and removal mechanisms to reprogram epigenetic information. PMID:25299455

  15. Imaging-Based High-Throughput Screening Assay To Identify New Molecules with Transmission-Blocking Potential against Plasmodium falciparum Female Gamete Formation

    PubMed Central

    Miguel-Blanco, Celia; Lelièvre, Joël; Delves, Michael J.; Bardera, Ana I.; Presa, Jesús L.; López-Barragán, María José; Ruecker, Andrea; Marques, Sara; Sinden, Robert E.

    2015-01-01

    In response to a call for the global eradication of malaria, drug discovery has recently been extended to identify compounds that prevent the onward transmission of the parasite, which is mediated by Plasmodium falciparum stage V gametocytes. Lately, metabolic activity has been used in vitro as a surrogate for gametocyte viability; however, as gametocytes remain relatively quiescent at this stage, their ability to undergo onward development (gamete formation) may be a better measure of their functional viability. During gamete formation, female gametocytes undergo profound morphological changes and express translationally repressed mRNA. By assessing female gamete cell surface expression of one such repressed protein, Pfs25, as the readout for female gametocyte functional viability, we developed an imaging-based high-throughput screening (HTS) assay to identify transmission-blocking compounds. This assay, designated the P. falciparum female gametocyte activation assay (FGAA), was scaled up to a high-throughput format (Z′ factor, 0.7 ± 0.1) and subsequently validated using a selection of 50 known antimalarials from diverse chemical families. Only a few of these agents showed submicromolar 50% inhibitory concentrations in the assay: thiostrepton, methylene blue, and some endoperoxides. To determine the best conditions for HTS, a robustness test was performed with a selection of the GlaxoSmithKline Tres Cantos Antimalarial Set (TCAMS) and the final screening conditions for this library were determined to be a 2 μM concentration and 48 h of incubation with gametocytes. The P. falciparum FGAA has been proven to be a robust HTS assay faithful to Plasmodium transmission-stage cell biology, and it is an innovative useful tool for antimalarial drug discovery which aims to identify new molecules with transmission-blocking potential. PMID:25801574

  16. A new channel for the formation of hydrogen cyanide in CH2-N2 systems

    NASA Technical Reports Server (NTRS)

    Laufer, A. H.; Bass, A. M.

    1978-01-01

    The reaction between N2 and either the singlet or the triplet electronic state of CH2 is investigated in order to shed light on the formation of NO in fuel-rich hydrocarbon flames. For the reaction of N2 and the triplet CH2, a rate constant less than or equal to 10 to the minus 16th power cu cm/molecule-sec is obtained. The time history of hydrogen cyanide production from the CH2-N2 systems is discussed as a basis for understanding the possible reaction routes from HCN to NO.

  17. [Anonymity and gamete donation].

    PubMed

    Bujan, L; Le Lannou, D; Kunstmann, J-M

    2012-08-01

    In France the gamete donation is based on the major principles: anonymity, no payment, solidarity and this mode of procreation can be used only if a medical indication is present in recipient couples. In prerequisite and during the revision of the law of bioethics, a wide debate took place about the anonymity of gamete donation. The objectives of this article is to review the concept of the anonymity and its links with the questions of the origin, the secret of the modalities of the conception and the mourning of the fertility, children, donors and the recipient couples waiting for gamete donation. The international situation is also addressed. The contribution of the CECOS, the centers which practice the sperm and the egg donations is highlighted. The anonymity cannot be discussed without addressing all these links and the complexity of this particular mode of conception. To date, the French society has maintained the anonymity in the new law of bioethics. PMID:23141592

  18. In Vitro Assessment of Gamete Integrity

    EPA Science Inventory

    Drug and xenobiotics can compromise reproductive function by impairing gamete physiology and thereby blocking fertilization, or by damaging gamete DNA or chromatin and thereby causing pregnancy failure or birth defects. tandard measures of gamete integrity, such as morphology, mo...

  19. Spermatids as male gametes.

    PubMed

    Ogura, A; Yanagimachi, R

    1995-01-01

    Intracytoplasmic sperm injection (ICSI) is becoming increasingly popular in human infertility clinics as an efficient method for the treatment of male infertility. It is proposed that spermatids can be used as substitutes for spermatozoa if men are unable to produce sperm in their testes. At least in the hamster and mouse, the nuclei of round spermatids were capable of participating in syngamy when incorporated into homologous mature oocytes either by microsurgical ICSI or electrofusion. Normal mouse offspring were born after after electrofusion of oocytes with round spermatids. When culture in vitro of spermatogonia and spermatocytes is perfected, then spermatids, transforming spermatids and spermatozoa will all be able to be used as male gametes. PMID:7480833

  20. Artificial gametes from stem cells

    PubMed Central

    Moreno, Inmaculada; Míguez-Forjan, Jose Manuel

    2015-01-01

    The generation of artificial gametes is a real challenge for the scientific community today. In vitro development of human eggs and sperm will pave the way for the understanding of the complex process of human gametogenesis and will provide with human gametes for the study of infertility and the onset of some inherited disorders. However, the great promise of artificial gametes resides in their future application on reproductive treatments for all these people wishing to have genetically related children and for which gamete donation is now their unique option of parenthood. This is the case of infertile patients devoid of suitable gametes, same sex couples, singles and those fertile couples in a high risk of transmitting serious diseases to their progeny. In the search of the best method to obtain artificial gametes, many researchers have successfully obtained human germ cell-like cells from stem cells at different stages of differentiation. In the near future, this field will evolve to new methods providing not only viable but also functional and safe artificial germ cells. These artificial sperm and eggs should be able to recapitulate all the genetic and epigenetic processes needed for the correct gametogenesis, fertilization and embryogenesis leading to the birth of a healthy and fertile newborn. PMID:26161331

  1. Reinforcement of gametic isolation in Drosophila.

    PubMed

    Matute, Daniel R

    2010-03-01

    Reinforcement, a process by which natural selection increases reproductive isolation between populations, has been suggested to be an important force in the formation of new species. However, all existing cases of reinforcement involve an increase in mate discrimination between species. Here, I report the first case of reinforcement of postmating prezygotic isolation (i.e., barriers that act after mating but before fertilization) in animals. On the slopes of the African island of São Tomé, Drosophila yakuba and its endemic sister species D. santomea hybridize within a well-demarcated hybrid zone. I find that D. yakuba females from within this zone, but not from outside it, show an increase in gametic isolation from males of D. santomea, an apparent result of natural selection acting to reduce maladaptive hybridization between species. To determine whether such a barrier could evolve under laboratory conditions, I exposed D. yakuba lines derived from allopatric populations to experimental sympatry with D. santomea, and found that both behavioral and gametic isolation become stronger after only four generations. Reinforcement thus appears to be the best explanation for the heightened gametic isolation seen in sympatry. This appears to be the first example in animals in which natural selection has promoted the evolution of stronger interspecific genetic barriers that act after mating but before fertilization. This suggests that many other genetic barriers between species have been increased by natural selection but have been overlooked because they are difficult to study.

  2. Weak maser emission of methyl formate toward Sagittarius B2(N) in the green bank telescope PRIMOS survey

    SciTech Connect

    Faure, A.; Wiesenfeld, L.; Szalewicz, K.

    2014-03-10

    A non-LTE radiative transfer treatment of cis-methyl formate (HCOOCH{sub 3}) rotational lines is presented for the first time using a set of theoretical collisional rate coefficients. These coefficients have been computed in the temperature range 5-30 K by combining coupled-channel scattering calculations with a high accuracy potential energy surface for HCOOCH{sub 3}-He. The results are compared to observations toward the Sagittarius B2(N) molecular cloud using the publicly available PRIMOS survey from the Green Bank Telescope. A total of 49 low-lying transitions of methyl formate, with upper levels below 25 K, are identified. These lines are found to probe a presumably cold (∼30 K), moderately dense (∼10{sup 4} cm{sup –3}), and extended region surrounding Sgr B2(N). The derived column density of ∼4 × 10{sup 14} cm{sup –2} is only a factor of ∼10 larger than the column density of the trans conformer in the same source. Provided that the two conformers have the same spatial distribution, this result suggests that strongly non-equilibrium processes must be involved in their synthesis. Finally, our calculations show that all detected emission lines with a frequency below 30 GHz are (collisionally pumped) weak masers amplifying the continuum of Sgr B2(N). This result demonstrates the importance and generality of non-LTE effects in the rotational spectra of complex organic molecules at centimeter wavelengths.

  3. Mitochondrial reticulation in shoot apical meristem cells of Arabidopsis provides a mechanism for homogenization of mtDNA prior to gamete formation.

    PubMed

    Seguí-Simarro, José M; Staehelin, L Andrew

    2009-03-01

    Plant mitochondria are typically portrayed as being small, oval organelles. However, a recent study has demonstrated that the chondriome of shoot apical meristem (SAM) cells of Arabidopsis thaliana is unique in having two types of mitochondria, a large, central, tentaculate mitochondrion and variable numbers of small, oval mitochondria in the cell cortex that fuse with and fission from the tentaculate mitochondrion. The tentaculate mitochondrion wraps around the nucleus and persists throughout the cell cycle, undergoing distinct changes in morphology and size in a cell cycle-dependent manner. Here we demonstrate that SAM cell plastids, which also contain DNA, do not reticulate, and address the question as to why SAM cell mitochondria but not plastids form reticulate structures. We postulate that the presence of a large, tentaculate mitochondrion in SAM cells provides an efficient means for homogenizing the mitochondrial DNA and proteins during vegetative life prior to gamete production, and that this mitochondrial architecture prevents speciation. The lack of plastid reticulation in the same cells most likely reflects on the fact that the individual plastids are much larger than the small mitochondria and therefore do not need to fuse to achieve efficient intermixing of their genomes.

  4. III. Gamete and embryo donation.

    PubMed

    2002-05-01

    Ethical considerations concerning gametes and embryo donation are discussed. Basic principles are outlined, focusing on the issues raised by the meaning of genetic links, regulation and the necessity for taking into account the welfare of the child. Relevant specific aspects concern anonymity, compensation for donation and the consent, screening and assessment of donors and recipients. PMID:11980773

  5. Measurements and Modeling of Nitric Oxide Formation in Counterflow, Premixed CH4/O2/N2 Flames

    NASA Technical Reports Server (NTRS)

    Thomsen, D. Douglas; Laurendeau, Normand M.

    2000-01-01

    Laser-induced fluorescence (LIF) measurements of NO concentration in a variety of CH4/O2/N2 flames are used to evaluate the chemical kinetics of NO formation. The analysis begins with previous measurements in flat, laminar, premixed CH4/O2/N2 flames stabilized on a water-cooled McKenna burner at pressures ranging from 1 to 14.6 atm, equivalence ratios from 0.5 to 1.6, and volumetric nitrogen/oxygen dilution ratios of 2.2, 3.1 and 3.76. These measured results are compared to predictions to determine the capabilities and limitations of the comprehensive kinetic mechanism developed by the Gas Research Institute (GRI), version 2.11. The model is shown to predict well the qualitative trends of NO formation in lean-premixed flames, while quantitatively underpredicting NO concentration by 30-50%. For rich flames, the model is unable to even qualitatively match the experimental results. These flames were found to be limited by low temperatures and an inability to separate the flame from the burner surface. In response to these limitations, a counterflow burner was designed for use in opposed premixed flame studies. A new LIF calibration technique was developed and applied to obtain quantitative measurements of NO concentration in laminar, counterflow premixed, CH4/O2/N2 flames at pressures ranging from 1 to 5.1 atm, equivalence ratios of 0.6 to 1.5, and an N2/O2 dilution ratio of 3.76. The counterflow premixed flame measurements are combined with measurements in burner-stabilized premixed flames and counterflow diffusion flames to build a comprehensive database for analysis of the GRI kinetic mechanism. Pathways, quantitative reaction path and sensitivity analyses are applied to the GRI mechanism for these flame conditions. The prompt NO mechanism is found to severely underpredict the amount of NO formed in rich premixed and nitrogen-diluted diffusion flames. This underprediction is traced to uncertainties in the CH kinetics as well as in the nitrogen oxidation chemistry

  6. Oviductal response to gametes and early embryos in mammals.

    PubMed

    Maillo, Veronica; Sánchez-Calabuig, Maria Jesus; Lopera-Vasquez, Ricaurte; Hamdi, Meriem; Gutierrez-Adan, Alfonso; Lonergan, Patrick; Rizos, Dimitrios

    2016-10-01

    The oviduct is a complex and organized thin tubular structure connecting the ovary with the uterus. It is the site of final sperm capacitation, oocyte fertilization and, in most species, the first 3-4days of early embryo development. The oviductal epithelium is made up of ciliary and secretory cells responsible for the secretion of proteins and other factors which contribute to the formation of the oviductal fluid. Despite significant research, most of the pathways and oviductal factors implicated in the crosstalk between gametes/early embryo and the oviduct remain unknown. Therefore, studying the oviductal environment is crucial to improve our understanding of the regulatory mechanisms controlling fertilization and embryo development. In vitro systems are a valuable tool to study in vivo pathways and mechanisms, particularly those in the oviducts which in livestock species are challenging to access. In studies of gamete and embryo interaction with the reproductive tract, oviductal epithelial cells, oviductal fluid and microvesicles co-cultured with gametes/embryos represent the most appropriate in vitro models to mimic the physiological conditions in vivo. PMID:27512123

  7. How safe is gamete micromanipulation by laser tweezers?

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten; Tromberg, Bruce J.; Tadir, Yona; Berns, Michael W.

    1998-04-01

    Laser tweezers, used as novel sterile micromanipulation tools of living cells, are employed in laser-assisted in vitro fertilization (IVF). For example, controlled spermatozoa transport with 1064 nm tweezers to human egg cells has been performed in European clinics in cases of male infertility. The interaction of approximately 100 mW near infrared (NIR) trapping beams at MW/cm2 intensity with human gametes results in low mean less than 2 K temperature increases and less than 100 pN trapping forces. Therefore, photothermal or photomechanical induced destructive effects appear unlikely. However, the high photon flux densities may induce simultaneous absorption of two NIR photons resulting in nonlinear interactions. These nonlinear interactions imply non-resonant two-photon excitation of endogenous cellular chromophores. In the case of less than 800 nm tweezers, UV- like damage effects may occur. The destructive effect is amplified when multimode cw lasers are used as tweezer sources due to longitudinal mode-beating effects and partial mode- locking. Spermatozoa damage within seconds using 760 nm traps due to formation of unstable ps pulses in a cw Ti:Sa ring laser is demonstrated. We recommend the use of greater than or equal to 800 nm traps for optical gamete micromanipulation. To our opinion, further basic studies on the influence of nonlinear effects of laser tweezers on human gamete are necessary.

  8. FORMATION OF PEPTIDE BONDS IN SPACE: A COMPREHENSIVE STUDY OF FORMAMIDE AND ACETAMIDE IN Sgr B2(N)

    SciTech Connect

    Halfen, D. T.; Ziurys, L. M.; Ilyushin, V. E-mail: lziurys@as.arizona.edu

    2011-12-10

    Extensive observations of acetamide (CH{sub 3}CONH{sub 2}) and formamide (NH{sub 2}CHO) have been conducted toward Sgr B2(N) at 1, 2, and 3 mm using the Submillimeter Telescope (SMT) and the 12 m antenna of the Arizona Radio Observatory. Over the frequency range 65-280 GHz, 132 transitions of acetamide have been observed as individual, distinguishable features, although in some cases they are partially blended. The unblended transitions in acetamide indicate V{sub LSR} = 63.2 {+-} 2.8 km s{sup -1} and {Delta}V{sub 1/2} = 12.5 {+-} 2.9 km s{sup -1}, line parameters that are very similar to that of formamide (NH{sub 2}CHO) and other organic species in Sgr B2(N). For formamide, 79 individual transitions were identified over the same frequency region. Rotational diagram analyses indicate the presence of two components for both species in Sgr B2(N). For acetamide, the colder component (E{sub u} < 40 K) exhibits a rotational temperature of T{sub rot} = 17 {+-} 4 K and a column density of N{sub tot} = 5.2 {+-} 3.5 Multiplication-Sign 10{sup 13} cm{sup -2}; the higher energy component has T{sub rot} = 171 {+-} 4 K and N{sub tot} = 6.4 {+-} 4.7 Multiplication-Sign 10{sup 14} cm{sup -2}. In the case of formamide, T{sub rot} = 26 {+-} 4 K and N{sub tot} = 1.6 {+-} 0.7 Multiplication-Sign 10{sup 14} cm{sup -2} for the colder component with T{sub rot} = 134 {+-} 17 K and N{sub tot} = 4.0 {+-} 1.2 Multiplication-Sign 10{sup 14} cm{sup -2} for the warmer region. The fractional abundances of acetamide are f (H{sub 2}) = 1.7 Multiplication-Sign 10{sup -11} and 2.1 Multiplication-Sign 10{sup -10} for the cold and warm components, and in formamide, f (H{sub 2}) = 5.3 Multiplication-Sign 10{sup -11} and 1.3 Multiplication-Sign 10{sup -10}. The similarity between the abundances and distributions of CH{sub 3}CONH{sub 2} and NH{sub 2}CHO suggests a synthetic connection. The abundance of acetamide, moreover, is only a factor of three lower than that of formaldehyde, and very similar to

  9. Kinetic modeling of the formation and growth of inorganic nano-particles during pulverized coal char combustion in O2/N2 and O2/CO2 atmospheres

    DOE PAGES

    Shaddix, Christopher R.; Niu, Yanqing; Hui, Shi'en; Wang, Shuai

    2016-08-01

    In this formation of nano-particles during coal char combustion, the vaporization of inorganic components in char and the subsequent homogeneous particle nucleation, heterogeneous condensation, coagulation, and coalescence play decisive roles. Furthermore, conventional measurements cannot provide detailed information on the dynamics of nano-particle formation and evolution, In this study, a sophisticated intrinsic char kinetics model that considers ash effects (including ash film formation, ash dilution, and ash vaporization acting in tandem), both oxidation and gasification by CO2 and H2O, homogeneous particle nucleation, heterogeneous vapor condensation, coagulation, and and coalescence mechanisms is developed and used to compare the temporal evolution of themore » number and size of nano-particles during coal char particle combustion as a function of char particle size, ash content, and oxygen content in O2/N2 and O2/CO2 atmospheres .« less

  10. Ion currents involved in gamete physiology.

    PubMed

    Gallo, Alessandra; Tosti, Elisabetta

    2015-01-01

    Gametes are electrogenic cells that modify their electrical properties in response to different stimuli. This behavior is due to the occurrence of ion currents flowing through ion channels located on the plasma membranes. The modulation of ion channels has been described during the processes of gamete maturation, activation and fertilization in most of the animal models studied. In particular, predominant ions involved in physiological events in oocyte and sperm have been recognized to be sodium, potassium and calcium. In this review, we give an overview on the occurrence, modulation and function of ion fluxes, from gametogenesis to early fertilization events, from marine animals to human. The implications for a dynamic role of ion currents in gamete physiology and their possible clinical and technological applications are discussed.

  11. Gamete activation: basic knowledge and clinical applications

    PubMed Central

    Tosti, Elisabetta; Ménézo, Yves

    2016-01-01

    Background The first clues to the process of gamete activation date back to nearly 60 years ago. The mutual activation of gametes is a crucial event during fertilization. In the testis and ovaries, spermatozoa and oocytes are in a state of meiotic and metabolic quiescence and require reciprocal signals in order to undergo functional changes that lead to competence for fertilization. First, the oocyte activates sperm by triggering motility, chemoattraction, binding and the acrosome reaction, culminating with the fusion of the two plasma membranes. At the end of this cascade of events, collectively known as sperm capacitation, sperm-induced oocyte activation occurs, generating electrical, morphological and metabolic modifications in the oocyte. Objective and rationale The aim of this review is to provide the current state of knowledge regarding the entire process of gamete activation in selected specific animal models that have contributed to our understanding of fertilization in mammals, including humans. Here we describe in detail the reciprocal induction of the two activation processes, the molecules involved and the mechanisms of cell interaction and signal transduction that ultimately result in successful embryo development and creation of a new individual. Search methods We carried out a literature survey with no restrictions on publication date (from the early 1950s to March 2016) using PubMed/Medline, Google Scholar and Web of Knowledge by utilizing common keywords applied in the field of fertilization and embryo development. We also screened the complete list of references published in the most recent research articles and relevant reviews published in English (both animal and human studies) on the topics investigated. Outcomes Literature on the principal animal models demonstrates that gamete activation is a pre-requisite for successful fertilization, and is a process common to all species studied to date. We provide a detailed description of the dramatic

  12. Random Genetic Drift and Gamete Frequency

    PubMed Central

    Mano, Shuhei

    2005-01-01

    An analytic expression of conditional expectation of transient gamete frequency, given that one of the two loci remains polymorphic, is obtained in terms of the diffusion process by calculating the moments of the distribution. Using this expression, a model where linkage disequilibrium is introduced by a single mutation is considered. The conditional expectation of the gamete frequency given that the locus with the mutant allele remains polymorphic is presented. The behavior is significantly different from the monotonic decrease observed in the deterministic model without random genetic drift. PMID:16371518

  13. 2006 Guidelines for Gamete and Embryo Donation.

    PubMed

    2006-11-01

    The 2006 Guidelines for Gamete and Embryo Donation provide the latest recommendations for evaluation of potential sperm, oocyte, and embryo donors, incorporating recent information about optimal screening and testing for sexually transmitted infections, genetic diseases, and psychological assessments. This revised American Society for Reproductive Medicine Practice Committee document incorporates recent information from the US Centers for Disease Control and Prevention, the US Food and Drug Administration, and the American Association of Tissue Banks, with which all programs offering gamete and embryo donation services must be thoroughly familiar. PMID:17055844

  14. Short pulse formation in a TEA CO{sub 2} laser using a CO{sub 2} - N{sub 2} - H{sub 2} gas mixture

    SciTech Connect

    Ivashchenko, M V; Karapuzikov, A I; Sherstov, I V

    2001-11-30

    The use of an optimal CO{sub 2} - N{sub 2} - H{sub 2} gas mixture with a high concentration of hydrogen (30% - 40%) was shown to allow the formation of high-power TEA CO{sub 2}-laser pulses with a base duration of {approx} 200 ns whose energy and peak power significantly exceed the parameters of pulses obtained in binary CO{sub 2} - H{sub 2} mixtures. Considering all the parameters, the helium-free 56% CO{sub 2} - 14% N{sub 2} - 30% H{sub 2} gas mixture at a pressure of 0.7 atm is optimal for the generation of short high-power pulses in the TEA CO{sub 2} laser. A small addition of nitrogen ([CO{sub 2}]/[N{sub 2}] {approx} 10 - 12) to the binary CO{sub 2} - H{sub 2} mixture not only substantially increases the pulse energy and peak power (by a factor of 3 - 3.5) but also shortens their duration at half-maximum with retention of the total (base) duration. (control of laser radiation parameters)

  15. CO2 + N2O mixture gas hydrate formation kinetics and effect of soil minerals on mixture-gas hydrate formation process

    NASA Astrophysics Data System (ADS)

    Enkh-Amgalan, T.; Kyung, D.; Lee, W.

    2012-12-01

    CO2 mitigation is one of the most pressing global scientific topics in last 30 years. Nitrous oxide (N2O) is one of the main greenhouse gases (GHGs) defined by the Kyoto Protocol and its global warming potential (GWP) of one metric ton is equivalent to 310 metric tons of CO2. They have similar physical and chemical properties and therefore, mixture-gas (50% CO2 + 50% N2O) hydrate formation process was studied experimentally and computationally. There were no significant research to reduce N20 gas and we tried to make hydrate to mitigate N20 and CO2 in same time. Mixture gas hydrate formation periods were approximately two times faster than pure N2O hydrate formation kinetic in general. The fastest induction time of mixture-gas hydrate formation observed in Illite and Quartz among various soil mineral suspensions. It was also observed that hydrate formation kinetic was faster with clay mineral suspensions such as Nontronite, Sphalerite and Montmorillonite. Temperature and pressure change were not significant on hydrate formation kinetic; however, induction time can be significantly affected by various chemical species forming under the different suspension pHs. The distribution of chemical species in each mineral suspension was estimated by a chemical equilibrium model, PHREEQC, and used for the identification of hydrate formation characteristics in the suspensions. With the experimental limitations, a study on the molecular scale modeling has a great importance for the prediction of phase behavior of the gas hydrates. We have also performed molecular dynamics computer simulations on N2O and CO2 hydrate structures to estimate the residual free energy of two-phase (hydrate cage and guest molecule) at three different temperature ranges of 260K, 273K, and 280K. The calculation result implies that N2O hydrates are thermodynamically stable at real-world gas hydrate existing condition within given temperature and pressure. This phenomenon proves that mixture-gas could be

  16. Increased complexity in interstellar chemistry: detection and chemical modeling of ethyl formate and n-propyl cyanide in Sagittarius B2(N)

    NASA Astrophysics Data System (ADS)

    Belloche, A.; Garrod, R. T.; Müller, H. S. P.; Menten, K. M.; Comito, C.; Schilke, P.

    2009-05-01

    Context: In recent years, organic molecules of increasing complexity have been found toward the prolific Galactic center source Sagittarius B2. Aims: We wish to explore the degree of complexity that the interstellar chemistry can reach in star-forming regions. Methods: We carried out a complete line survey of the hot cores Sgr B2(N) and (M) with the IRAM 30 m telescope in the 3 mm range, plus partial surveys at 2 and 1.3 mm. We analyzed this spectral survey in the local thermodynamical equilibrium approximation. We modeled the emission of all known molecules simultaneously, which allows us to search for less abundant, more complex molecules. We compared the derived column densities with the predictions of a coupled gas-phase and grain-surface chemical code. Results: We report the first detection in space of ethyl formate (C2H5OCHO) and n-propyl cyanide (C3H7CN) toward Sgr B2(N). The detection of n-propyl cyanide is based on refined spectroscopic parameters derived from combined analyses of available laboratory spectroscopic data. For each molecule, we identified spectral features at the predicted frequencies having intensities compatible with a unique rotation temperature. For an assumed source size of 3 arcsec, our modeling yields a column density of 5.4 × 1016 cm-2, a temperature of 100 K, and a linewidth of 7 km s-1 for ethyl formate. n-Propyl cyanide is detected with two velocity components having column densities of 1.5 × 1016 cm-2 and 6.6 × 1015 cm-2, respectively, for a source size of 3 arcsec, a temperature of 150 K, and a linewidth of 7 km s-1. The abundances of ethyl formate and n-propyl cyanide relative to H2 are estimated to be 3.6 × 10-9 and 1.0 × 10-9, respectively. We derived column density ratios of 0.8/15/1 for the related species t-HCOOH/CH3OCHO/C2H5OCHO and 108/80/1 for CH3CN/C2H5CN/C3H7CN. Our chemical modeling reproduces these ratios reasonably well. It suggests that the sequential, piecewise construction of ethyl and n-propyl cyanide from

  17. [Cultural diversity in gamete and embryos donation].

    PubMed

    Epelboin, S

    2014-09-01

    Through gamete and embryo donation have successively emerged new ways of designing individuals who, in turn, have generated mutations in the concept of parenthood. A debate is open to the society, which often raises ideological cleavages. Indeed, donation practices mobilize the conflicting interests of donor of gametes, the recipient couple, child, whose origins are complex, although his filiation is legally clear. Its place in the family genealogy can be examined in relation to other societies, which admit plural concepts called "classificatory" kinship. They set up role partition between parents and educators. Setting anthropological perspective provides a broadening of the reflection to answer questions from the donation practices, including genealogical questions of revelation to the child of his conception, his incorporation in family and social group and the importance of compensation of donation. PMID:25153433

  18. Ancestor embryos: embryonic gametes and genetic parenthood.

    PubMed

    Watt, Helen

    2014-11-01

    The proposal for reproducing human generations in vitro raises the question to what extent parenthood is possible in embryos and to what extent human rights and interests are dependent on conscious awareness. This paper argues that the interest in not being made a parent non-consensually for the benefit of others persists throughout the lifespan of the individual human organism. We do not become genetic parents by learning that we are parents; rather, we discover (or fail to discover) an existing genetic relationship between our offspring and ourselves. The claim to genetic parenthood of an embryo used for reproduction in vitro is, if anything, clearer than the claim of the adult for whom gametes are derived via ips cells, in that an embryo's cells, unlike an adult's somatic cells, are already functionally geared to producing gametes (among other types of cell). An embryo used to make gametes that are used in reproduction is immediately and non-consensually made a genetic parent and to that extent is wronged whether or not the parent embryo survives-as some could survive-the harvesting of cells. All human individuals carry objective interests in benefits appropriate to the kind of being they are; these include the stake in not being made a parent without one's consent, whether posthumously or otherwise.

  19. Gamete Recognition and Complementary Haplotypes in Sexual Penna Ageing Model

    NASA Astrophysics Data System (ADS)

    Cebrat, S.; Stauffer, D.

    In simulations of sexual reproduction with diploid individuals, we introduce female haploid gametes that recognize one specific allele of the genomes as a marker of the male haploid gametes. They fuse to zygotes preferably with male gametes having a different marker than their own. This gamete recognition enhances the advantage of complementary bit-strings in the simulated diploid individuals, at low recombination rates. Thus with rare recombinations the bit-strings evolve to be complementary; with recombination rates above approximately 0.1 they instead evolve under Darwinian purification selection, with few bits mutated.

  20. Gamete intrafallopian transfer: benefits of programmed stimulation.

    PubMed

    Pouly, J L; Janny, L; Canis, M; Vye, P; Boyer, C

    1989-12-01

    Fifty-six cycles of gamete intrafallopian transfer (GIFT) were performed after programming by administration of norethisterone in the previous cycle. Ovarian hyperstimulation was achieved with clomifene citrate and human menopausal gonadotropins. Only one GIFT was performed during a weekend (1.8%). The implantation rate was 41.1% and the evolutive pregnancy rate 30.4%. The endocrinological influence of these regimens are discussed by comparison of those observed in an in vitro fertilization program. The main influence is a decreased serum luteinizing hormone (LH) level in the preovulatory phase. PMID:2591558

  1. Gamete donation: ethical implications for donors.

    PubMed

    Shenfield, Francoise

    1999-01-01

    The interests of gamete donors have only recently been recognized in assisted reproduction; traditionally, the interests of the patients (typically a couple) and the prospective child are paramount. However, assisted reproduction would not be possible without donors, and the simple utilitarian view would be to place their interests first to maximize the availability of the practice. There are several ethical issues on both sides of the donor--recipient equation, some of which are mutual and others are in conflict. For example, the word 'donation' implies there is no payment. Informed consent for donation is essential if the autonomy of the donor is to be respected, and includes information about the results of screening. This is a sensitive issue, especially when pathology is found in a donor who is not being screened for his or her own immediate benefit. Counselling may result in donors refusing to take part, but may also lead to selection by the person recruiting the donors, sometimes as a consequence of examining the motivation of the donor. In this case, the main problem is the ethical basis of the selection process. Other aspects of gamete donation may lead to a conflict of interests between the donor, the recipients and even the prospective child, particularly in terms of anonymity and the information that is made available about the specific circumstances of donation. Implications and support counselling are essential tools in achieving an acceptable balance for all parties involved.

  2. [Gamete donation in an in vitro fertilization program].

    PubMed

    Zhang, L Z

    1993-12-01

    Two cases of gamete donation in an IVF program were reported in this paper. In the first case the wife with recurrent abortions was found to have chromosomal abnormality, her karyotype was 45,XX,-14,-14 + rob (14 Q 14 Q). She became pregnant after IVF-ET with donated ova, and was delivered of a normal male baby on June 12, 1992. The baby's karyotype was normal. The blood group of both the husband and wife was O, while that of the baby was B. The baby suffered from icterus neonatorum as a result of ABO incompatibility but recovered quickly after treatment. Further DNA finger print analysis of the husband, wife and baby, combined with the history of egg donation IVF, proved the relationship of the parents with the baby. In the second case the husband's karyotype was 46,XY, t(4; 9) (4Q+; 9Q-). The wife had also history of recurrent abortions. Since 1989, the wife received sperm donation IUI 5 times in another hospital without success. IVF-ET with donated sperms was performed in November 1991 resulting in clinical pregnancy. She was delivered of a pair of twins, one male and one female on July 20, 1992. The possibilities of different types of gamete formation during meiosis in carriers of chromosomal balanced translocation were briefly discussed. Donation of oocytes could be realized only in an IVF program, which is also the only way to propagate for the family. However, IVF with donated sperms is indicated in women with blocked tubes besides the male factor or after repeated failures of other assisted reproductive technologies. PMID:8137642

  3. Gamete attachment process revealed in flowering plant fertilization.

    PubMed

    Mori, Toshiyuki; Igawa, Tomoko

    2014-01-01

    Sex-possessing organisms perform sexual reproduction, in which gametes from different sexes fuse to produce offspring. In most eukaryotes, one or both sex gametes are motile, and gametes actively approach each other to fuse. However, in flowering plants, the gametes of both sexes lack motility. Two sperm cells (male gametes) that are contained in a pollen grain are recessively delivered via pollen tube elongation. After the pollen tube bursts, sperm cells are released toward the egg and central cells (female gametes) within an ovule ( Fig. 1 ). The precise mechanism of sperm cell movement after the pollen tube bursts remains unknown. Ultimately, one sperm cell fuses with the egg cell and the other one fuses with the central cell, producing an embryo and an endosperm, respectively. Fertilization in which 2 sets of gamete fusion events occur, called double fertilization, has been known for over 100 y. The fact that each morphologically identical sperm cell precisely recognizes its fusion partner strongly suggests that an accurate gamete interaction system(s) exists in flowering plants. PMID:25517689

  4. Multilocus half-tetrad analysis and centromere mapping in citrus: evidence of SDR mechanism for 2n megagametophyte production and partial chiasma interference in mandarin cv 'Fortune'.

    PubMed

    Cuenca, J; Froelicher, Y; Aleza, P; Juárez, J; Navarro, L; Ollitrault, P

    2011-10-01

    The genetic structure of 2n gametes and, particularly, the parental heterozygosity restitution at each locus depends on the meiotic process by which they originated, with first-division restitution and second-division restitution (SDR) being the two major mechanisms. The origin of 2n gametes in citrus is still controversial, although sexual polyploidisation is widely used for triploid seedless cultivar development. In this study, we report the analysis of 2n gametes of mandarin cv 'Fortune' by genotyping 171 triploid hybrids with 35 simple sequence repeat markers. The microsatellite DNA allele counting-peak ratios method for allele-dosage evaluation proved highly efficient in segregating triploid progenies and allowed half-tetrad analysis (HTA) by inferring the 2n gamete allelic configuration. All 2n gametes arose from the female genitor. The observed maternal heterozygosity restitution varied between 10 and 82%, depending on the locus, thus SDR appears to be the mechanism underlying 2n gamete production in mandarin cv 'Fortune'. A new method to locate the centromere, based on the best fit between observed heterozygosity restitution within a linkage group and theoretical functions under either partial or no chiasmata interference hypotheses was successfully applied to linkage group II. The maximum value of heterozygosity restitution and the pattern of restitution along this linkage group would suggest there is partial chiasma interference. The implications of such a restitution mechanism for citrus breeding are discussed.

  5. Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures

    PubMed Central

    2011-01-01

    Background Unreduced gametes (gametes with the somatic chromosome number) may provide a pathway for evolutionary speciation via allopolyploid formation. We evaluated the effect of genotype and temperature on male unreduced gamete formation in Brassica allotetraploids and their interspecific hybrids. The frequency of unreduced gametes post-meiosis was estimated in sporads from the frequency of dyads or giant tetrads, and in pollen from the frequency of viable giant pollen compared with viable normal pollen. Giant tetrads were twice the volume of normal tetrads, and presumably resulted from pre-meiotic doubling of chromosome number. Giant pollen was defined as pollen with more than 1.5 × normal diameter, under the assumption that the doubling of DNA content in unreduced gametes would approximately double the pollen cell volume. The effect of genotype was assessed in five B. napus, two B. carinata and one B. juncea parents and in 13 interspecific hybrid combinations. The effect of temperature was assessed in a subset of genotypes in hot (day/night 30°C/20°C), warm (25°C/15°C), cool (18°C/13°C) and cold (10°C/5°C) treatments. Results Based on estimates at the sporad stage, some interspecific hybrid genotypes produced unreduced gametes (range 0.06 to 3.29%) at more than an order of magnitude higher frequency than in the parents (range 0.00% to 0.11%). In nine hybrids that produced viable mature pollen, the frequency of viable giant pollen (range 0.2% to 33.5%) was much greater than in the parents (range 0.0% to 0.4%). Giant pollen, most likely formed from unreduced gametes, was more viable than normal pollen in hybrids. Two B. napus × B. carinata hybrids produced 9% and 23% unreduced gametes based on post-meiotic sporad observations in the cold temperature treatment, which was more than two orders of magnitude higher than in the parents. Conclusions These results demonstrate that sources of unreduced gametes, required for the triploid bridge hypothesis of

  6. Mammalian diversity: gametes, embryos and reproduction.

    PubMed

    Behringer, Richard R; Eakin, Guy S; Renfree, Marilyn B

    2006-01-01

    The class Mammalia is composed of approximately 4800 extant species. These mammalian species are divided into three subclasses that include the monotremes, marsupials and eutherians. Monotremes are remarkable because these mammals are born from eggs laid outside of the mother's body. Marsupial mammals have relatively short gestation periods and give birth to highly altricial young that continue a significant amount of 'fetal' development after birth, supported by a highly sophisticated lactation. Less than 10% of mammalian species are monotremes or marsupials, so the great majority of mammals are grouped into the subclass Eutheria, including mouse and human. Mammals exhibit great variety in morphology, physiology and reproduction. In the present article, we highlight some of this remarkable diversity relative to the mouse, one of the most widely used mammalian model organisms, and human. This diversity creates challenges and opportunities for gamete and embryo collection, culture and transfer technologies.

  7. Enigmas of mammalian gamete form and function.

    PubMed

    Bedford, J Michael

    2004-05-01

    The gametes of man and some other Eutheria have been manipulated successfully for practical reasons, but many gaps remain in our basic understanding of the way that they function. This situation stems not least from a failure to recognize the extent to which eutherian spermatozoa and eggs, and elements related to their operation, have come to differ from those of other groups. Novel features in the male that reflect this include a radical design of the sperm head with the acrosome seeming to function primarily in egg-coat binding rather than its lysis, a multifaceted post-testicular sperm maturation and an androgen/low-temperature-regulated system of sperm storage--both tied to the epididymis, a variable male accessory sex gland complex, and descent of the testis and epididymis to a scrotum. In the female, such novelties are represented in a need for sperm capacitation, in an unusual regulation of sperm transport within the oviduct, in the cumulus oophorus and character of the zona pellucida around the small egg, and in a unique configuration of gamete fusion. The collective evidence now suggests that many of these features reflect a new fertilisation strategy or its consequences, with most being causally linked. One initial 'domino' in this regard appears to be the small yolkless state of the egg and its intolerance for polyspermy, as determinants of the unusual mode of oviductal sperm transport and possibly the existence and form of the cumulus oophorus. However, a particularly influential first 'domino' appears to be the physical character of the eutherian zona pellucida. This differs from the egg coats of other animal groups by virtue of a resilient elasticity and thickness. These qualities allow this primary and often only coat to stretch and so persist during later expansion of the blastocyst, usually until close to implantation. At the same time, the dimensions, physical character, and particularly the relative protease-insensitivity of the zona appear to

  8. Gametic isolation in guppies (Poecilia reticulata)

    PubMed Central

    Ludlow, A.M; Magurran, A.E

    2006-01-01

    Post-mating reproductive isolating mechanisms may be among the earliest reproductive barriers to emerge among incipient species. Trinidadian guppy, Poecilia reticulata, populations in the Caroni and Oropouche drainages in Northern Trinidad exhibit marked genetic divergence and provide an ideal system in which to search for these barriers. We inseminated virgin females with equal amounts of sperm from two males, a ‘native’ male from the female's own population and a ‘foreign’ male from the other drainage. Artificial insemination ensured that mating order and mate choice did not affect the outcome. Paternities were assigned to the resulting broods using microsatellite markers. As predicted, sperm from native males had precedence over foreign sperm. Moreover, this effect was symmetrical for both drainages. In contrast, we detected no native sperm precedence in controls, in which females received sperm from the same and another population within the same drainage. Our results show that gametic isolation can arise between geographically proximate, though genetically divergent, populations of a single species and highlight the potential role of this process in speciation. PMID:16959638

  9. Gamete Donor Consent and Human Embryonic Stem Cell Research.

    PubMed

    Siegel, Andrew W

    2015-06-01

    There is a lack of consensus on whether the derivation and use of human embryonic stem cells (hESCs) from embryos remaining after infertility treatment morally require the informed consent of third-party gamete donors who contributed to the creation of the embryos. The principal guidelines for oversight and funding of hESC research in the United States make minimal or no demands for consent from gamete donors. In this article, I consider the arguments supporting and opposing gamete donor consent for hESC research and embryo research more broadly. I argue that it is not morally permissible to use leftover embryos in research without the informed consent of gamete donors, and that we should place restrictions on the use of existing hESC lines that may have been derived without informed consent. While the standard argument for this position relies on an appeal to gamete donors' interest in controlling what happens with their genetic material, I identify shortcomings with the standard approach and seek instead to locate the deeper moral foundations for gamete donor consent in rights to bodily integrity.

  10. Ploidy frequencies in plants with ploidy heterogeneity: fitting a general gametic model to empirical population data

    PubMed Central

    Suda, Jan; Herben, Tomáš

    2013-01-01

    Genome duplication (polyploidy) is a recurrent evolutionary process in plants, often conferring instant reproductive isolation and thus potentially leading to speciation. Outcome of the process is often seen in the field as different cytotypes co-occur in many plant populations. Failure of meiotic reduction during gametogenesis is widely acknowledged to be the main mode of polyploid formation. To get insight into its role in the dynamics of polyploidy generation under natural conditions, and coexistence of several ploidy levels, we developed a general gametic model for diploid–polyploid systems. This model predicts equilibrium ploidy frequencies as functions of several parameters, namely the unreduced gamete proportions and fertilities of higher ploidy plants. We used data on field ploidy frequencies for 39 presumably autopolyploid plant species/populations to infer numerical values of the model parameters (either analytically or using an optimization procedure). With the exception of a few species, the model fit was very high. The estimated proportions of unreduced gametes (median of 0.0089) matched published estimates well. Our results imply that conditions for cytotype coexistence in natural populations are likely to be less restrictive than previously assumed. In addition, rather simple models show sufficiently rich behaviour to explain the prevalence of polyploids among flowering plants. PMID:23193129

  11. Gamete production patterns, ploidy, and population genetics reveal evolutionary significant units in hybrid water frogs (Pelophylax esculentus).

    PubMed

    Pruvost, Nicolas B M; Hoffmann, Alexandra; Reyer, Heinz-Ulrich

    2013-09-01

    The European water frog Pelophylax esculentus is a natural hybrid between P. lessonae (genotype LL) and P. ridibundus (RR). It reproduces through hybridogenesis, eliminating one parental genome from its germline and producing gametes containing the genome of the other parental species. According to previous studies, this elimination and transmission pattern is very diverse. In mixed populations, where only diploid hybrids (LR) live in sympatry and mate with one or both parental species, the excluded genome varies among regions, and the remaining genome is transmitted clonally to haploid gametes. In all-hybrid populations consisting of diploid (LR) and triploid (LLR and/or LRR) frogs, diploid individuals also produce gametes clonally (1n in males, 2n in females), whereas triploids eliminate the genome they have in single copy and produce haploid gametes containing the recombined other genome. However, here, too, regional differences seem to exist, and some triploids have been reported to produce diploid gametes. In order to systematically study such regional and genotype differences in gamete production, their potential origin, and their consequences for the breeding system, we sampled frogs from five populations in three European countries, performed crossing experiments, and investigated the genetic variation through microsatellite analysis. For four populations, one in Poland, two in Germany, and one in Slovakia, our results confirmed the elimination and transmission pattern described above. In one Slovakian population, however, we found a totally different pattern. Here, triploid males (LLR) produce sperm with a clonally transmitted diploid LL genome, rather than a haploid recombined L genome, and LR females clonally produce haploid R eggs, rather than diploid LR eggs. These differences among the populations in gamete production go along with differences in genomotype composition, breeding system (i.e., the way triploids are produced), and genetic variation

  12. Multilocus half-tetrad analysis and centromere mapping in citrus: evidence of SDR mechanism for 2n megagametophyte production and partial chiasma interference in mandarin cv ‘Fortune'

    PubMed Central

    Cuenca, J; Froelicher, Y; Aleza, P; Juárez, J; Navarro, L; Ollitrault, P

    2011-01-01

    The genetic structure of 2n gametes and, particularly, the parental heterozygosity restitution at each locus depends on the meiotic process by which they originated, with first-division restitution and second-division restitution (SDR) being the two major mechanisms. The origin of 2n gametes in citrus is still controversial, although sexual polyploidisation is widely used for triploid seedless cultivar development. In this study, we report the analysis of 2n gametes of mandarin cv ‘Fortune' by genotyping 171 triploid hybrids with 35 simple sequence repeat markers. The microsatellite DNA allele counting-peak ratios method for allele-dosage evaluation proved highly efficient in segregating triploid progenies and allowed half-tetrad analysis (HTA) by inferring the 2n gamete allelic configuration. All 2n gametes arose from the female genitor. The observed maternal heterozygosity restitution varied between 10 and 82%, depending on the locus, thus SDR appears to be the mechanism underlying 2n gamete production in mandarin cv ‘Fortune'. A new method to locate the centromere, based on the best fit between observed heterozygosity restitution within a linkage group and theoretical functions under either partial or no chiasmata interference hypotheses was successfully applied to linkage group II. The maximum value of heterozygosity restitution and the pattern of restitution along this linkage group would suggest there is partial chiasma interference. The implications of such a restitution mechanism for citrus breeding are discussed. PMID:21587302

  13. Gamete quality in fish: evaluation parameters and determining factors.

    PubMed

    Valdebenito, Iván I; Gallegos, Patricia C; Effer, Brian R

    2015-04-01

    The quality of fish gametes, both male and female, are determined by several factors (age, management, feeding, chemical and physical factors, water quality, etc.) that have an impact on the survivability of embryos, larvae and/or fry in the short or long term. One of the most important factors is gamete ageing, especially for those species that are unable to spawn naturally in hatcheries. The chemical and physical factors in hatcheries and the nutrition that they provide can significantly alter harvest quality, especially from females; as a rule, males are more tolerant of stress conditions produced by inadequate feeding, management and/or poor water conditions. The stress produced on broodstock by inadequate conditions in hatcheries can produce adverse effects on gamete quality, survival rates, and the embryonic eggs after hatching.

  14. Recommendations for gamete and embryo donation: a committee opinion.

    PubMed

    2013-01-01

    This document provides the latest recommendations for evaluation of potential sperm, oocyte, and embryo donors, incorporating recent information about optimal screening and testing for sexually transmitted infections, genetic diseases, and psychological assessments. This revised document incorporates recent information from the U.S. Centers for Disease Control and Prevention, the US Food and Drug Administration, and the American Association of Tissue Banks, with which all programs offering gamete and embryo donation services must be thoroughly familiar, and replaces the document titled, "2008 Guidelines for Gamete and Embryo Donation: A Practice Committee Report," last published in Fertil Steril 2008;90:S30-44. PMID:23095142

  15. Production of diploid male gametes in Arabidopsis by cold-induced destabilization of postmeiotic radial microtubule arrays.

    PubMed

    De Storme, Nico; Copenhaver, Gregory P; Geelen, Danny

    2012-12-01

    Whole-genome duplication through the formation of diploid gametes is a major route for polyploidization, speciation, and diversification in plants. The prevalence of polyploids in adverse climates led us to hypothesize that abiotic stress conditions can induce or stimulate diploid gamete production. In this study, we show that short periods of cold stress induce the production of diploid and polyploid pollen in Arabidopsis (Arabidopsis thaliana). Using a combination of cytological and genetic analyses, we demonstrate that cold stress alters the formation of radial microtubule arrays at telophase II and consequently leads to defects in postmeiotic cytokinesis and cell wall formation. As a result, cold-stressed male meiosis generates triads, dyads, and monads that contain binuclear and polynuclear microspores. Fusion of nuclei in binuclear and polynuclear microspores occurs spontaneously before pollen mitosis I and eventually leads to the formation of diploid and polyploid pollen grains. Using segregation analyses, we also found that the majority of cold-induced dyads and triads are genetically equivalent to a second division restitution and produce diploid gametes that are highly homozygous. In a broader perspective, these findings offer insights into the fundamental mechanisms that regulate male gametogenesis in plants and demonstrate that their sensitivity to environmental stress has evolutionary significance and agronomic relevance in terms of polyploidization.

  16. Formation and X-ray Structures of Eight- and Sixteen-Membered Rings (ArC)(n)()N(2)(n)()(SPh)(n)() [n = 2, Ar = 4-XC(6)H(4) (X = Br, CF(3)); n = 4, Ar = 4-BrC(6)H(4)] and the Electronic Structures of (HC)(2)N(4)(SH)(2) and (HC)(2)N(4)(SH)(2)(2)(-).

    PubMed

    Chivers, Tristram; Parvez, Masood; Vargas-Baca, Ignacio; Ziegler, Tom; Zoricak, Peter

    1997-04-01

    Optimum yields of heterocyclic products are obtained when the reaction of 4-XC(6)H(4)CN(2)(SiMe(3))(3) (X = Br, CF(3)) with PhSCl in a 1:3 molar ratio in CH(2)Cl(2) is carried out at -100 degrees C followed by the mixture being warmed to -70 degrees C for 16 h. Under these conditions the eight-membered rings (4-XC(6)H(4))(2)C(2)N(4)S(2)Ph(2) (1b, X = Br; 1c, X = CF(3)) are obtained in 64 and 80% yields, respectively, in addition to the purple diazenes Z,E,Z-PhSN(4-XC(6)H(4))CN=NC(C(6)H(4)X-4)NSPh (2b, 8%; 2c, 19%) and, in the case of X = Br, the sixteen-membered ring (4-BrC(6)H(4))(4)C(4)N(8)S(4)Ph(4) (3) (8%). With a reaction time of 40 h the yield of 3 is increased to 25%. By contrast, the reaction of 3-BrC(6)H(4)CN(2)(SiMe(3))(3) with 3 equiv of PhSCl at -70 degrees C gives Z,E,Z-PhSN(3-BrC(6)H(4))CN=NC(3-BrC(6)H(4))NSPh in 75% yield. A possible pathway for the formation of cyclic products is proposed. The solid-state structures of 1b, 1c, and 3 were determined by X-ray crystallography. The eight-membered rings 1b and 1c adopt long boat conformations with the phenyl groups (attached to S) in equatorial positions. Density functional theory (DFT) calculations for the model ring system (HC)(2)N(4)(SH)(2) reveal that the observed C(2)(v)() geometry is the result of a second-order Jahn-Teller distortion of the planar (D(2)(h)()) structure. The chair conformer (C(2)(h)()) is only ca. 10 kJ mol(-)(1) higher in energy than the boat conformer. The hypothetical dianion (HC)(2)N(4)(SH)(2)(2)(-) is predicted to have a transannular S.S contact of about 2.5 Å. The sixteen-membered ring 3 has a cradle-like structure with S(4) symmetry.

  17. Experimental and numerical study of the role of NCN in prompt-NO formation in low-pressure CH{sub 4}-O{sub 2}-N{sub 2} and C{sub 2}H{sub 2}-O{sub 2}-N{sub 2} flames

    SciTech Connect

    Lamoureux, N.; Desgroux, P.; El Bakali, A.; Pauwels, J.F.

    2010-10-15

    We report an experimental and modeling study on prompt-NO formation in low-pressure (5.3 kPa) premixed flames. Special emphasis is given to the quantitative detection (and prediction) of NCN, whose role in prompt-NO formation has recently been confirmed in alkane flames. Here a rich ({phi} = 1.25) CH{sub 4}-O{sub 2}-N{sub 2} flame and rich ({phi} = 1.25) and stoichiometric C{sub 2}H{sub 2}-O{sub 2}-N{sub 2} flames have been investigated. Absolute concentration profiles of CH and NCN radicals and NO species are obtained by combining laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS). Temperature profile is determined in each flame using OH and NO-LIF thermometry. Flame modeling is performed to determine the role of NCN in prompt-NO formation and to test the capacity of the present chemical mechanisms to predict some intermediate species involved in prompt-NO formation. The methane flame is modeled using GDFkin registered 3.0{sub N}CN mechanism [El Bakali et al., Fuel 85 (2006), 896-909]. The acetylene flames are modeled using the Lindstedt and Skevis C/H/O mechanism [Lindstedt and Skevis, Proc. Combust. Inst. 28 (2000), 1801-1807], completed by the submechanism issued from GDFkin registered 3.0{sub N}CN for nitrogen chemistry. This submechanism includes the initiation reaction CH + N{sub 2} = NCN + H. Rate constants of NO-sensitive reactions of the submechanism are modified by taking into account the recent literature. In particular, the C{sub 2}O route could be explored thanks to a significant presence of C{sub 2}O in acetylene flames. Globally, the modified submechanism of nitrogen chemistry coupled with the two hydrocarbon mechanisms leads to a satisfying prediction of NCN and NO mole fraction profiles, even though refinements of rate constant determination is still required. The role of NCN in prompt-NO formation in acetylene flames is demonstrated. (author)

  18. Postmenopausal Motherhood Reloaded: Advanced Age and In Vitro Derived Gametes

    PubMed Central

    Cutas, Daniela; Smajdor, Anna

    2015-01-01

    In this paper we look at the implications of an emerging technology for the case in favor of, or against, postmenopausal motherhood. Technologies such as in vitro derived gametes (sperm and eggs derived from nonreproductive cells) have the potential to influence the ways in which reproductive medicine is practiced, and are already bringing new dimensions to debates in this area. We explain what in vitro derived gametes are and how their development may impact on the case of postmenopausal motherhood. We briefly review some of the concerns that postmenopausal motherhood has raised—and the implications that the successful development, and use in reproduction, of artificial gametes might have for such concerns. The concerns addressed include arguments from nature, risks and efficacy, reduced energy of the mother, and maternal life expectancy. We also consider whether the use of in vitro derived gametes to facilitate postmenopausal motherhood would contribute to reinforcing a narrow, geneticized account of reproduction and a pro-reproductive culture that encourages women to produce genetically related offspring at all costs. PMID:26074667

  19. Cryopreservation of gametes and embryos of non-domestic species.

    PubMed

    Leibo, S P; Songsasen, N

    2002-01-01

    Many species of mammals are threatened or endangered. Methods of assisted reproduction that are being used with increasing frequency to produce offspring of domestic animals and humans are often viewed as offering innovative ways to reproduce non-domestic species as well. Uncounted millions of live young of domestic or laboratory species have been produced from gametes and embryos stored at -70 degrees C or below, sometimes for as long as 25 to 35 yrs. Such methods of cryopreservation are now being applied with increasing frequency and urgency to preserve gametes and embryos of non-domestic and threatened species to establish "genome resource banks" or "frozen zoos." But levels of success to produce live young from such cryopreserved gametes or embryos vary considerably from species to species, as well as from individual to individual. It is sometimes thought that differences among species in fundamental characteristics of their gametes may determine the efficacy of cryopreservation and the production of live young. However, it may not be that ineffective cryopreservation is responsible for low success rates. Rather, the limiting factor may be insufficient information and knowledge of the most basic reproductive biology of such non-domestic species. Even standard methods of cryopreservation may be completely adequate to act as a "temporary" expedient to preserve germplasm of non-domestic species to permit time to acquire a fuller understanding of the biology and behavior of non-domestic species.

  20. DURATIONS OF GAMETE MOTILITY AND CONJUGATION ABILITY OF ULVA COMPRESSA (ULVOPHYCEAE)(1).

    PubMed

    Kuwano, Kazuyoshi; Hashioka, Takashi; Nishihara, Gregory N; Iima, Masafumi

    2012-04-01

    The present study was designed to develop a technique for crossing and to gain insight into how sexual reproduction contributes to the maintenance of local populations of Ulva compressa L. To examine the durations of gamete motility and conjugation ability, freshly released gametes were incubated for various periods of time prior to mixing both mating types. The conjugation ability of the gametes gradually declined after being released from the thalli when the gametes were incubated without mixing with the opposite mating type. The ability to conjugate decreased by half after 6 h, although most of the gametes remained motile. The gametes released 4 h later had the same level of conjugation ability when mixed immediately after releasing. When the mature thalli were wrapped in a moist paper towel to prevent gametes from being released, the gametes were preservable for 7 h without a significant decrease in their conjugation ability. Conjugation occurred soon after mixing gametes of both mating types and reached a plateau after 30 s. However, conjugation rates did not exceed a rate of ∼70%, even though freshly released gametes were used. Interestingly, a portion of the gametes newly conjugated 30 min after mixing both mating types, and conjugation rates reached a second plateau at ∼90%. Gametes with delayed conjugation are provided some period of time that allows them to be transported away and increases their chances of mating with more distant populations, thus contributing to the maintenance of genetic variation. PMID:27009729

  1. Formation of higher chloride complexes of Np(IV) and Pu(IV) in water-stable room-temperature ionic liquid [BuMeIm][Tf2N].

    PubMed

    Nikitenko, Sergey I; Moisy, Philippe

    2006-02-01

    A UV/vis/near-IR spectroscopic study shows that in [BuMeIm][(CF3SO2)2N] hydrophobic room-temperature ionic liquid solutions, [BuMeIm]2[AnCl6] complexes, where BuMeIm+ is 1-n-butyl-3-methylimidazolium and An(IV) is Np(IV) or Pu(IV), have an octahedral An(IV) environment similar to that observed in solid complexes. Water has no influence on the absorption spectra of AnCl6(2-) complexes, indicating their stability to hydrolysis in ionic liquid. Adding [BuMeIm]Cl modifies the UV/vis/near-IR absorption spectra of An(IV) in the ionic liquid and causes solids to precipitate. The solid-state reflectance spectra of the precipitates reveal considerable differences from the corresponding An(IV) hexachloro complexes. A voltammetric study indicates that AnCl6(2-) complexes are electrochemically inert in [BuMeIm][(CF3SO2)2N] at the glassy carbon working electrode. By contrast, quasi-reversible electrochemical reduction An(IV)/An(III) and An(IV) oxidation are observed in ionic liquids in the presence of [BuMeIm]Cl. The oxidation wave of noncoordinated chloride ions interferes with the An(IV) oxidation waves. The spectroscopic and voltammetric data clearly indicate the formation of nonoctahedral actinide(IV) chloride complexes with a Cl-/An(IV) ratio exceeding 6/1 in [BuMeIm][(CF3SO2)2N] in excess chloride ions.

  2. Further Evidence for a Polymorphism in Gametic Segregation in the Tetraploid Treefrog HYLA VERSICOLOR Using a Glutamate Oxaloacetic Transaminase Locus

    PubMed Central

    Danzmann, Roy G.; Bogart, James P.

    1983-01-01

    Intra- and interspecific cross combinations between the tetraploid treefrog Hyla versicolor, and between H. versicolor and the diploid treefrog Hyla chrysoscelis were performed. Progeny phenotypes resulting from these crosses were examined electrophoretically using a polymorphic glutamate oxaloacetic transminase (GOT-1) locus, to determine the mechanism of chromosome segregation in H. versicolor, and to test theoretical expectations for isozyme expression in interspecific (2n x 4n or 4n x 2n) hybrids. In some intraspecific tetraploid crosses progeny phenotypes fit a disomic mode of segregation, whereas in other crosses a tetrasomic mode of segregation was the most probable. Additional crosses produced phenotypic ratios that conformed to either a disomic or tetrasomic mode of segregation. These results suggest that a polymorphism, with respect to segregation of gametes, exists in H. versicolor, resulting from differences in chromosome pairings during meiosis I. This polymorphism in gametic segregation occurred in both sexes. Certain crosses, however, produced phenotypic ratios that did not conform to any chromosome segregation model. Progeny phenotypes observed from most interspecific crosses conformed to expected interspecific isozyme staining intensity models. Symmetrical heterozygotes, representing either a single dose for both alternate alleles or double doses for both alternate alleles, were also observed. Such phenotypes are unexpected in triploid progeny. A null allele was postulated to account for the aberrant segregation ratios and phenotypes observed in certain intra- and interspecific crosses. PMID:6852524

  3. Role of melatonin on production and preservation of gametes and embryos: a brief review.

    PubMed

    Cruz, Maria Helena Coelho; Leal, Claudia Lima Verde; da Cruz, Jurandir Ferreira; Tan, Dun-Xian; Reiter, Russel J

    2014-03-01

    The aim of this brief review is to clarify the role of melatonin in the production and preservation of mammalian gametes and embryos. Melatonin is an indoleamine synthesized from tryptophan in the pineal gland and other organs that operates as a hypothalamic-pituitary-gonadal axis modulator and regulates the waxing and waning of seasonal reproductive competence in photoperiodic mammals. A major function of the melatonin rhythm is to transmit information about the length of the daily photoperiod to the circadian and circannual systems in order to provide time-of-day and time-of-year information, respectively, to the organism. Melatonin is also a powerful antioxidant and anti-apoptotic agent, which is due to its direct scavenging of toxic oxygen derivatives and its ability to reduce the formation of reactive species. Mammalian gametes and embryos are highly vulnerable to oxidative stress due to the presence of high lipid levels; during artificial breeding procedures, these structures are exposed to dramatic changes in the microenvironment, which have a direct bearing on their function and viability. Free radicals influence the balance between oxidation-reduction reactions, disturb the transbilayer-phospholipid asymmetry of the plasma membrane and enhance lipid peroxidation. Melatonin, due to its amphiphilic nature, is undoubtedly useful in tissues by protecting them from free radical-mediated oxidative damage and cellular death. The supplementation of melatonin to semen extender or culture medium significantly improves sperm viability, oocyte competence and blastocyst development in vitro. PMID:24559971

  4. The CKI1 Histidine Kinase Specifies the Female Gametic Precursor of the Endosperm.

    PubMed

    Yuan, Li; Liu, Zhenning; Song, Xiaoya; Johnson, Cameron; Yu, Xiaolin; Sundaresan, Venkatesan

    2016-04-01

    Since the discovery of double fertilization, it has been recognized that flowering plants produce two highly dimorphic female gametes, the egg cell and central cell. These give rise, respectively, to the embryo and the endosperm, a nourishing tissue unique to flowering plants. Here we show that in Arabidopsis, endosperm formation requires the CYTOKININ INDEPENDENT 1 (CKI1) histidine kinase, an activator of the cytokinin signaling pathway, which specifies central cells and restricts egg cell fate. Dimorphism of the two adjacent gametes is mechanistically established in the syncytial embryo sac by spatially restricted CKI1 expression, followed by translocation of ER-localized CKI1 protein via nuclear migration. Cell specification by CKI1 likely involves activation of the cytokinin signaling pathway mediated by histidine phosphotransferases. Ectopic CKI1 expression generates non-propagating seeds with dual fertilized endosperms and no embryos. We conclude that CKI1-directed specification of the endosperm precursor central cell results in seeds containing an embryo and an endosperm. PMID:27046830

  5. Role of melatonin on production and preservation of gametes and embryos: a brief review.

    PubMed

    Cruz, Maria Helena Coelho; Leal, Claudia Lima Verde; da Cruz, Jurandir Ferreira; Tan, Dun-Xian; Reiter, Russel J

    2014-03-01

    The aim of this brief review is to clarify the role of melatonin in the production and preservation of mammalian gametes and embryos. Melatonin is an indoleamine synthesized from tryptophan in the pineal gland and other organs that operates as a hypothalamic-pituitary-gonadal axis modulator and regulates the waxing and waning of seasonal reproductive competence in photoperiodic mammals. A major function of the melatonin rhythm is to transmit information about the length of the daily photoperiod to the circadian and circannual systems in order to provide time-of-day and time-of-year information, respectively, to the organism. Melatonin is also a powerful antioxidant and anti-apoptotic agent, which is due to its direct scavenging of toxic oxygen derivatives and its ability to reduce the formation of reactive species. Mammalian gametes and embryos are highly vulnerable to oxidative stress due to the presence of high lipid levels; during artificial breeding procedures, these structures are exposed to dramatic changes in the microenvironment, which have a direct bearing on their function and viability. Free radicals influence the balance between oxidation-reduction reactions, disturb the transbilayer-phospholipid asymmetry of the plasma membrane and enhance lipid peroxidation. Melatonin, due to its amphiphilic nature, is undoubtedly useful in tissues by protecting them from free radical-mediated oxidative damage and cellular death. The supplementation of melatonin to semen extender or culture medium significantly improves sperm viability, oocyte competence and blastocyst development in vitro.

  6. Acrosome Reaction as a Preparation for Gamete Fusion.

    PubMed

    Cuasnicú, Patricia S; Da Ros, Vanina G; Weigel Muñoz, Mariana; Cohen, Débora J

    2016-01-01

    The acrosome reaction (AR) is a universal requisite for sperm-egg fusion. However, whereas through the animal kingdom fusion of spermatozoa with the egg plasma membrane occurs via the inner acrosomal membrane exposed after the AR, in eutherian mammals, gamete fusion takes place through a specialized region of the acrosome known as the equatorial segment (ES) which becomes fusogenic only after the AR is completed. This chapter focuses on the different molecular mechanisms involved in the acquisition of the fusogenicity of the ES after the AR. We provide an update of the knowledge about the proteins proposed to have a role in this process either by modifying cytoskeletal and/or membrane molecules or by relocalizing to the ES after the AR to subsequently participate in gamete fusion. PMID:27194355

  7. Stem cells to gametes: how far should we go?

    PubMed

    Whittaker, Peter

    2007-03-01

    Murine embryonic stem cells have recently been shown to be capable of differentiating in vitro into oocytes or sperm. Should these findings be duplicated using human embryonic stem cells, this would raise a number of social and ethical concerns, some specific to these particular developments, others shared with other aspects of stem cell research. This review outlines the properties of stem cells and their conversion to gametes. Concerns raised include embryo destruction, quality of gametes derived in this way, possibility for children with two male biological parents, movement towards germ line gene therapy and 'designer babies', and the future impacts on health service provisions. It is important that public discussion of some of these issues should take place.

  8. Stem cells to gametes: how far should we go?

    PubMed

    Whittaker, Peter

    2007-03-01

    Murine embryonic stem cells have recently been shown to be capable of differentiating in vitro into oocytes or sperm. Should these findings be duplicated using human embryonic stem cells, this would raise a number of social and ethical concerns, some specific to these particular developments, others shared with other aspects of stem cell research. This review outlines the properties of stem cells and their conversion to gametes. Concerns raised include embryo destruction, quality of gametes derived in this way, possibility for children with two male biological parents, movement towards germ line gene therapy and 'designer babies', and the future impacts on health service provisions. It is important that public discussion of some of these issues should take place. PMID:17454202

  9. Standard molar enthalpy of combustion and formation of quaternary ammonium tetrachlorozincate [n-CnH2n+1 N(CH3)3]2 ZnCl4.

    PubMed

    Ren, Biyan; Zhang, Shuying; Ruan, Bei; Wu, Kezhong; Zhang, Jianjun

    2013-12-01

    The standard molar enthalpy of combustion (Δc H (o) m) and formation (Δf H (o) m) of quaternary ammonium tetrachlorozincate [n-CnH2n+1N(CH3)3]2ZnCl4 have been determined for the hydrocarbon chain length from even number 8 to 18 of carbon atoms (n) by an oxygen-bomb combustion calorimeter. The results indicated that the values of Δc H (o) m increased and Δf H (o) m decreased with increasing chain length and showed a linear dependence on the number of carbon atoms, which were caused by that the order and rigidity of the hydrocarbon chain decreased with increasing the carbon atoms. The linear regression equations are -Δc H (o) m =1440.50n +3730.67 and -Δf H (o) m = -85.32n + 1688.22.

  10. Theoretical Investigations on the Formation and Dehydrogenation Reaction Pathways of H(NH2BH2)nH (n=1-4) Oligomers: Importance of Dihydrogen Interactions (DHI)

    SciTech Connect

    Li, Jun; Kathmann, Shawn M.; Hu, Han-Shi; Schenter, Gregory K.; Autrey, Thomas; Gutowski, Maciej S.

    2010-09-06

    The H(NH2BH2)nH oligomers are possible products from dehydrogenation of ammonia borane (NH3BH3) and ammonium borohydride (NH4BH4), which belong to a class of boron-nitrogen-hydrogen (BNHx) compounds that are promising materials for chemical hydrogen storage. Understanding the kinetics and reaction pathways of formation of these oligomers and their further dehydrogenation is essential for developing BNHx-based hydrogen storage materials. We have performed computational modeling using density functional theory (DFT), ab initio wavefunction theory, and Car-Parrinello molecular dynamics (CPMD) simulations on the energetics and formation pathways for the H(NH2BH2)nH (n=1-4) oligomers, polyaminoborane (PAB), from NH3BH3 monomers and the subsequent dehydrogenation steps to form polyiminoborane (PIB). Through transition state searches and evaluation of the intrinsic reaction coordinates, we have investigated the B-N bond cleavage, the reactions of NH3BH3 molecule with intermediates, dihydrogen release through intra- and intermolecular hydrogen transfer, dehydrocoupling/cyclization of the oligomers, and the dimerization of NH3BH3 molecules. We discovered the formation mechanism of H(NH2BH2)n+1H oligomers through reactions of the H(NH2BH2)nH oligomers first with BH3 followed by reactions with NH3 and the release of H2, where the BH3 and NH3 intermediates are formed through dissociation of NH3BH3. We also found that the dimerization of the NH3BH3 molecules to form c-(NH2BH2)2 is slightly exothermic, with an unexpected transition state that leads to the simultaneous release of two H2 molecules. The dehydrogenations of the oligomers are also exothermic, typically by less than 10 kcal/(mol of H2), with the largest exothermicity for n=3. The transition state search shows that the one-step direct dehydrocoupling cyclization of the oligomers is not a favored pathway because of high activation barriers. The dihydrogen bonding, in which protic (HN) hydrogens interact with hydridic

  11. Standard molar enthalpy of combustion and formation of quaternary ammonium tetrachlorozincate [n-CnH2n+1 N(CH3)3]2 ZnCl4.

    PubMed

    Ren, Biyan; Zhang, Shuying; Ruan, Bei; Wu, Kezhong; Zhang, Jianjun

    2013-12-01

    The standard molar enthalpy of combustion (Δc H (o) m) and formation (Δf H (o) m) of quaternary ammonium tetrachlorozincate [n-CnH2n+1N(CH3)3]2ZnCl4 have been determined for the hydrocarbon chain length from even number 8 to 18 of carbon atoms (n) by an oxygen-bomb combustion calorimeter. The results indicated that the values of Δc H (o) m increased and Δf H (o) m decreased with increasing chain length and showed a linear dependence on the number of carbon atoms, which were caused by that the order and rigidity of the hydrocarbon chain decreased with increasing the carbon atoms. The linear regression equations are -Δc H (o) m =1440.50n +3730.67 and -Δf H (o) m = -85.32n + 1688.22. PMID:23519475

  12. Central role of altruism in the recruitment of gamete donors.

    PubMed

    Pennings, Guido

    2015-03-01

    This paper explores problems associated with using altruism as the central value in gamete donation, and in doing so draws on empirical data that sheds light on why gamete donors choose to donate. Donation of bodily material is, arguably, supposed to be motivated by altruism, and this is the view taken by many European governments. Other values are often ignored or rejected as morally inappropriate. This paper analyses some conceptual and practical problems with the use of altruism as the motivation to determine moral acceptability-drawing on empirical data that suggests gamete donors are not motivated purely by altruism, and that motivations are in fact quite complex. Two problems are first analysed: (1) how do we distinguish altruistic from non-altruistic donations and (2) how do we distinguish between removing barriers and providing incentives. A final question, triggered by the Nuffield Council on Bioethics' report, is whether the meaning of the payment should be decided on the basis of an a priori definition or on the basis of the donors' subjective experience. It is concluded that there are different legitimate core values in donation, which should be balanced. In order to value the good generated by donation, donors with mixed motives should be accepted, as long as helping others is an important motive and also features in their motivation. PMID:25743052

  13. Gendering gametes: The unequal contributions of sperm and egg donors.

    PubMed

    Hertz, Rosanna; Nelson, Margaret K; Kramer, Wendy

    2015-12-01

    This paper compares three groups of gestational mothers who relied on gametes from donors they did not know. The three groups are women who have conceived with donor sperm and their own eggs, women who have conceived with donor eggs and a partner's sperm, and women who have conceived with embryos composed of both donor eggs and donor sperm. The paper explores three issues. First, it considers whether intending parents select sperm and egg donors for different attributes both when they are chosen as the only donor and when they are chosen as donors contributing to an entire embryo. Second, it examines how women imagine the donor. Finally, it looks at how women conceptualize the donor as an individual who contributes to their child's characteristics. Two significant findings emerged in this analysis of survey data. First, the data show that gametes are gendered with different attributes both when those gametes are separate and even more so when seen as complementary parts of a whole. Second, the data show that women minimize the impact of the egg donor (both when a sole contribution and especially when part of the complementary whole) and thus ignore the influence or impact of the egg donor relative to how they make sense of the influence or impact of the sperm donor. The data for this study comes from an online survey developed by the authors. PMID:26520059

  14. Gendering gametes: The unequal contributions of sperm and egg donors.

    PubMed

    Hertz, Rosanna; Nelson, Margaret K; Kramer, Wendy

    2015-12-01

    This paper compares three groups of gestational mothers who relied on gametes from donors they did not know. The three groups are women who have conceived with donor sperm and their own eggs, women who have conceived with donor eggs and a partner's sperm, and women who have conceived with embryos composed of both donor eggs and donor sperm. The paper explores three issues. First, it considers whether intending parents select sperm and egg donors for different attributes both when they are chosen as the only donor and when they are chosen as donors contributing to an entire embryo. Second, it examines how women imagine the donor. Finally, it looks at how women conceptualize the donor as an individual who contributes to their child's characteristics. Two significant findings emerged in this analysis of survey data. First, the data show that gametes are gendered with different attributes both when those gametes are separate and even more so when seen as complementary parts of a whole. Second, the data show that women minimize the impact of the egg donor (both when a sole contribution and especially when part of the complementary whole) and thus ignore the influence or impact of the egg donor relative to how they make sense of the influence or impact of the sperm donor. The data for this study comes from an online survey developed by the authors.

  15. Embryonic stem-cell gametes: the new frontier in human reproduction.

    PubMed

    Master, Zubin

    2006-04-01

    As infertility increases and gamete donations decline, an alternate source of sex cells may prove valuable for research and infertility treatment. This article examines the social and scientific value of gametes derived from the differentiation of established human embryonic stem (ES)-cell lines (ES-cell-derived gametes) and customized gametes created using nuclear transfer technologies to contain a haploid set of genes creating children genetically related to parent(s). ES-cell-derived gametes may be valuable as a resource for biomedical research, instruction and training in assisted reproductive technologies and perhaps for creating children. The creation of children by ES-cell-derived and customized gametes may not result in psychological harm to children but customized gametes may lead to physical harm to children or an accumulation of gene mutations in a population. Although the creation of new types of children using ES-cell gametes provides more reproductive choices to both fertile and infertile individuals, the risk or physical harm to children from customized gametes may be so severe that the scope of reproductive liberty must be limited. Further scientific and ethical analysis of the creation of children by ES-cell gametes is required.

  16. Segregation for Sexual Seed Production in Paspalum as Directed by Male Gametes of Apomictic Triploid Plants

    PubMed Central

    Martínez, Eric J.; Acuña, Carlos A.; Hojsgaard, Diego H.; Tcach, Mauricio A.; Quarin, Camilo L.

    2007-01-01

    Background and Aims Gametophytic apomixis is regularly associated with polyploidy. It has been hypothesized that apomixis is not present in diploid plants because of a pleiotropic lethal effect associated with monoploid gametes. Rare apomictic triploid plants for Paspalum notatum and P. simplex, which usually have sexual diploid and apomictic tetraploid races, were acquired. These triploids normally produce male gametes through meiosis with a range of chromosome numbers from monoploid (n = 10) to diploid (n = 20). The patterns of apomixis transmission in Paspalum were investigated in relation to the ploidy levels of gametes. Methods Intraspecific crosses were made between sexual diploid, triploid and tetraploid plants as female parents and apomictic triploid plants as male parents. Apomictic progeny were identified by using molecular markers completely linked to apomixis and the analysis of mature embryo sacs. The chromosome number of the male gamete was inferred from chromosome counts of each progeny. Key Results The chromosome numbers of the progeny indicated that the chromosome input of male gametes depended on the chromosome number of the female gamete. The apomictic trait was not transmitted through monoploid gametes, at least when the progeny was diploid. Diploid or near-diploid gametes transmitted apomixis at very low rates. Conclusions Since male monoploid gametes usually failed to form polyploid progenies, for example triploids after 4x × 3x crosses, it was not possible to determine whether apomixis could segregate in polyploid progenies by means of monoploid gametes. PMID:17766843

  17. Identification of higher plant GlsA, a putative morphogenesis factor of gametic cells.

    PubMed

    Mori, Toshiyuki; Kuroiwa, Haruko; Higashiyama, Tetsuya; Kuroiwa, Tsuneyoshi

    2003-06-27

    GlsA has been identified in an asexual-reproductive-cell (gonidia)-deficient mutant of Volvox as a chaperone-like protein essential for gonidia production. In this study, we isolated an angiosperm glsA (LlglsA) gene expressed during Lilium longiflorum pollen development. Immunoblot analyses showed that the strong LlGlsA expression occurred in the generative cell and its pattern during pollen development corresponded to that of alpha-tubulin. Morphological analyses succeeded in visualizing the dispersion of the strong LlGlsA signal in developing generative cells. In addition, multiple-immunofluorescence staining of LlGlsA and alpha-tubulin revealed that some of the dot-like LlGlsA signals were co-localized with microtubule filaments. From those results, we suggest that angiosperm GlsA functions as a chaperone modifying various structures during male gametic cell formation. PMID:12804602

  18. Thermodynamics of Boroxine Formation from the Aliphatic Boronic Acid Monomers R–B(OH)2 (R = H, H3C, H2N, HO, and F): A Computational Investigation

    PubMed Central

    Bhat, Krishna L.; Markham, George D.; Larkin, Joseph D.; Bock, Charles W.

    2011-01-01

    Boroxines are the 6-membered cyclotrimeric dehydration products of organoboronic acids: 3 R– B(OH)2 → R3B3O3 + 3 H2O, and in recent years have emerged as a useful class of organoboron molecules with applications in organic synthesis both as reagents and catalysts, as structural components in boronic acid derived pharmaceutical agents, as anion acceptors and electrolyte additives for battery materials [AL Korich and PM Iovine, Dalton Trans. 39 (2010) 1423–1431]. Second-order Møller-Plesset perturbation theory, in conjunction with the Dunning-Woon correlation-consistent cc-pVDZ, aug-cc-pVDZ, cc-pVTZ, and aug-cc-pVTZ basis sets, was used to investigate the structures and relative energies of the endo-exo, anti, and syn conformers of the aliphatic boronic acids R–B(OH)2 (R = H, H3C, H2N, HO, and F), as well as the thermodynamics of their boroxine formation; single-point calculations at the MP2/aug-cc-pVQZ, MP2/aug-cc-pV5Z, and CCSD(T)/aug-cc-pVTZ level using the MP2/aug-cc-pVTZ optimized geometries were also performed in selected cases. The endo-exo conformer was generally lowest in energy in vacuo, as well as in PCM and CPCM models of aqueous and carbon tetrachloride media. The values of ΔH2980 for boroxine formation via dehydration from the endo-exo conformers of these aliphatic boronic acids ranged from −2.9 for (H2N)3B3O3 to +12.2 kcal/mol for H3B3O3 at the MP2/aug-cc-pVTZ level in vacuo; for H3B3O3 the corresponding values in PCM:UFF implicit carbon tetrachloride and aqueous media were +11.2 and +9.8 kcal/mol, respectively. Based on our calculations, we recommend that ΔHf(298 K) for boroxine listed in the JANAF compilation needs to be revised from −290.0 kcal/mol to approximately −277.0 kcal/mol. PMID:21650154

  19. Understanding transgenerational epigenetic inheritance via the gametes in mammals.

    PubMed

    Daxinger, Lucia; Whitelaw, Emma

    2012-01-31

    It is known that information that is not contained in the DNA sequence - epigenetic information - can be inherited from the parent to the offspring. However, many questions remain unanswered regarding the extent and mechanisms of such inheritance. In this Review, we consider the evidence for transgenerational epigenetic inheritance via the gametes, including cases of environmentally induced epigenetic changes. The molecular basis of this inheritance remains unclear, but recent evidence points towards diffusible factors, in particular RNA, rather than DNA methylation or chromatin. Interestingly, many cases of epigenetic inheritance seem to involve repeat sequences.

  20. [In vitro strategies for human gametes production from stem cells].

    PubMed

    Tosca, Lucie; Courtot, Anne-Marie; Bennaceur-Griscelli, Annelise; Tachdjian, Gérard

    2011-10-01

    Embryonic stem cells (ESC) are self-renewal and pluripotent cells that are able to differentiate in vitro into several cell types in favourable conditions. Technical protocols for in vitro gametes production have been developed in mice and human species. The functionality of such differentiated cells is not always analysed and an early meiotic arrest is a current observation. These kinds of experimentations have also been tested from human induced pluripotent stem cells (IPSC). However, differentiation ends shortly at the primordial germ cell stage.

  1. Mandatory counseling for gamete donation recipients: ethical dilemmas.

    PubMed

    Benward, Jean

    2015-09-01

    Mental health professionals have engaged in mandatory pretreatment counseling and assessment of patients seeking treatment at IVF programs in the United States since the 1980s. At present, most recipient patients undergoing IVF with egg or embryo donation in the United States are required to meet with a mental health professional for one pretreatment session. Mandatory counseling of gamete recipients is fraught with ethical questions for the mental health professional. Attention to issues of autonomy, confidentiality, role clarity, along with self-evaluation and openness with the patient can help lessen the impact of these ethical challenges. PMID:26235569

  2. Recent microfluidic devices for studying gamete and embryo biomechanics.

    PubMed

    Lai, David; Takayama, Shuichi; Smith, Gary D

    2015-06-25

    The technical challenges of biomechanic research such as single cell analysis at a high monetary cost, labor, and time for just a small number of measurements is a good match to the strengths of microfluidic devices. New scientific discoveries in the fertilization and embryo development process, of which biomechanics is a major subset of interest, is crucial to fuel the continual improvement of clinical practice in assisted reproduction. The following review will highlight some recent microfluidic devices tailored for gamete and embryo biomechanics where biomimicry arises as a major theme of microfluidic device design and function, and the application of fundamental biomechanic principles are used to improve outcomes of cryopreservation.

  3. Regulatory considerations for global transfer of cryopreserved fish gametes

    USGS Publications Warehouse

    Jenkins, Jill A.; Tiersch, Terrence R.; Green, Christopher C.

    2011-01-01

    Federal and state resource managers, scientists, lawmakers, business and development investors, and the general public all struggle with issues surrounding the conservation of our biological heritage, especially in the face of increased population growth and consequent anthropogenic disturbances. Conservation interests include recovering exploited aquatic populations, decreasing the loss of genetic diversity, and reintroducing locally depleted species. However, research on husbandry and other techniques critical to implementing conservation strategies is often not started until few individuals remain. A program in the cryopreservation of gametes and embryos from aquatic species would address several of these conservation concerns by allowing the establishment of gene banks

  4. Recent microfluidic devices for studying gamete and embryo biomechanics.

    PubMed

    Lai, David; Takayama, Shuichi; Smith, Gary D

    2015-06-25

    The technical challenges of biomechanic research such as single cell analysis at a high monetary cost, labor, and time for just a small number of measurements is a good match to the strengths of microfluidic devices. New scientific discoveries in the fertilization and embryo development process, of which biomechanics is a major subset of interest, is crucial to fuel the continual improvement of clinical practice in assisted reproduction. The following review will highlight some recent microfluidic devices tailored for gamete and embryo biomechanics where biomimicry arises as a major theme of microfluidic device design and function, and the application of fundamental biomechanic principles are used to improve outcomes of cryopreservation. PMID:25801423

  5. Performance of non-motile male gametes in the sea: analysis of paternity and fertilization success in a natural population of a red seaweed, Gracilaria gracilis

    PubMed Central

    Engel, C. R.; Wattier, R.; Destombe, C.; Valero, M.

    1999-01-01

    In haploid–diploid red seaweeds, the dispersal of male gametes is presumed limited due to their lack of flagella. It has been suggested that this group suffers from sperm limitation and, consequently, that fertilization is relatively inefficient. Fertilization in most floridean rhodophytes results in the formation a cystocarp, a swelling on the haploid female thallus housing the diploid zygote and its thousands of diploid daughter spores. To study the performance of non-motile male gametes in the sea, we evaluated both female and male fertilization success in a natural population of the red marine alga Gracilaria gracilis. Female fertilization success, estimated by cystocarp yield per unit female thallus, was evaluated with respect to the availability of male gametes. Male fertilization success, estimated by the individual contribution of different males to zygotes, was assessed by paternity analyses on 350 cystocarps produced in one reproductive season using two microsatellite loci. The results show that cystocarp yield is not sperm limited and that the large variation in male fertilization success cannot be solely explained by the distance travelled by the male gamete to find a mate. Taken together, the results suggest that, not only is fertilization efficient, but that male–male competition and/or female choice may play a role in shaping population mating patterns.

  6. The gametic synapse: RNA transfer to the bovine oocyte.

    PubMed

    Macaulay, Angus D; Gilbert, Isabelle; Caballero, Julieta; Barreto, Rodrigo; Fournier, Eric; Tossou, Prudencio; Sirard, Marc-André; Clarke, Hugh J; Khandjian, Édouard W; Richard, Francois J; Hyttel, Poul; Robert, Claude

    2014-10-01

    Even after several decades of quiescent storage in the ovary, the female germ cell is capable of reinitiating transcription to build the reserves that are essential to support early embryonic development. In the current model of mammalian oogenesis, there exists bilateral communication between the gamete and the surrounding cells that is limited to paracrine signaling and direct transfer of small molecules via gap junctions existing at the end of the somatic cells' projections that are in contact with the oolemma. The purpose of this work was to explore the role of cumulus cell projections as a means of conductance of large molecules, including RNA, to the mammalian oocyte. By studying nascent RNA with confocal and transmission electron microscopy in combination with transcript detection, we show that the somatic cells surrounding the fully grown bovine oocyte contribute to the maternal reserves by actively transferring large cargo, including mRNA and long noncoding RNA. This occurrence was further demonstrated by the reconstruction of cumulus-oocyte complexes with transfected cumulus cells transferring a synthetic transcript. We propose selective transfer of transcripts occurs, the delivery of which is supported by a remarkable synapselike vesicular trafficking connection between the cumulus cells and the gamete. This unexpected exogenous contribution to the maternal stores offers a new perspective on the determinants of female fertility.

  7. Fertilization success in marine invertebrates: the influence of gamete age.

    PubMed

    Williams, Mark Elliott; Bentley, Matthew Graeme

    2002-02-01

    Gamete age has been postulated to be unimportant to the fertilization ecology of marine invertebrates. However, recent research suggests that, for some species at least, it may have a direct impact upon fertilization success. We present comparative data on the influence of gamete age on fertilization and development success in several marine invertebrates: the polychaetes Arenicola marina and Nereis virens and the asteroid echinoderm Asterias rubens. Oocytes are much longer lived in the polychaetes than in the echinoderm, with A. marina oocytes still capable of fertilizing and developing normally 96 h post-spawning. Developmental abnormalities and failure to reach blastula tend to occur well before the fertilizable life of the oocytes has expired. Sperm are similarly longer lived in the polychaetes; however, fertilizing capacity is markedly reduced following incubation in conspecific egg-conditioned seawater. These results are discussed in terms of the fertilization strategies of the three species. We further suggest that, for A. marina at least, longer-lived sperm and eggs are central to the fertilization strategy of this species.

  8. Gamete compatibility and sperm competition affect paternity and hybridization between sympatric Asterias sea stars.

    PubMed

    Harper, F M; Hart, M W

    2005-10-01

    Gamete interactions may strongly influence speciation and hybridization in sympatric broadcast-spawning marine invertebrates. We examined the role of gamete compatibility in species integrity using cross-fertilization studies between sympatric Asterias sea stars from a secondary contact zone in the northwest Atlantic. In crosses between single males and single females, gametes of both species were compatible and produced viable, fertile hybrid offspring, but with considerable variation in the receptivity of eggs to heterospecific sperm. Differential compatibility of heterospecific gametes was detected in sperm competition studies in which we used a nuclear DNA marker to assign paternity to larval offspring. Several families showed conspecific sperm precedence in A. forbesi eggs, and one family showed competitive superiority of A. forbesi sperm fertilizing A. rubens eggs. Gametic interactions are an important component of prezygotic reproductive isolation in sympatric Asterias. The interaction between gametes of these closely related sea stars is consistent with the function of gamete recognition systems that are known to mediate fertilization success and speciation in other marine invertebrates.

  9. Synchronous multispecific spawning on coral reefs: potential for hybridization and roles of gamete recognition.

    PubMed

    Babcock, R

    1995-01-01

    Problems of gamete recognition in corals and other mass-spawning invertebrates are potentially great. In 'mass spawnings', closely-related species or genera commonly spawn at the same time, or within 1 or 2 h of each other, increasing the potential for hybridization. Among mass-spawning corals, most of the species involved are hermaphrodites that package the gametes in buoyant bundles that float to the sea surface before breaking up. Local hydrodynamic features frequently act to aggregate gametes from many different species into slicks where both eggs and sperm can be viable for extended periods. Other mass-spawning invertebrate taxa, such as molluscs, polychaetes and various echinoderms, do not have buoyant gametes but also spawn with a high level of synchrony. Gametes of organisms participating in these spawning events must be able to successfully recognize conspecifics. If they cannot do this, either through sperm chemotaxis or by mechanisms at the level of sperm binding and penetration, there may be high levels of gamete wastage through hybridization. Alternatively, viable hybrids may be formed, a factor that could have contributed to the evolutionary history of mass-spawning taxa, as well as to the taxonomic difficulties that have plagued the taxonomy of groups such as reef-building corals. Within some mass-spawning taxa, pre-zygotic barriers to fertilization suggest relatively recent molecular evolution at gamete recognition loci.

  10. Ethical aspects of the use of stem cell derived gametes for reproduction.

    PubMed

    Mertes, Heidi; Pennings, Guido

    2010-09-01

    A lot of interest has been generated by the possibility of deriving gametes from embryonic stem cells and bone marrow stem cells. These stem cell derived gametes may become useful for research and for the treatment of infertility. In this article we consider prospectively the ethical issues that will arise if stem cell derived gametes are used in the clinic, making a distinction between concerns that only apply to embryonic stem cell derived gametes and concerns that are also relevant for gametes derived from adult stem cells. At present, it appears preferable to use non-embryonic stem cells for the derivation of gametes. Adult stem cell derived gametes do not present any problems with regard to the moral status of the human embryo, bypass the safety risks linked to SCNT and do not present any ambiguity or novel problems with regard to informed consent, psychological consequences for the child or genetic parenthood. A remaining ethical concern, however, regards the safety of the procedure in terms of the welfare of the resulting children. This should spark a thorough reflection on how far one must go to accommodate a person's wish to have a genetically related child.

  11. In Vitro Gamete Differentiation from Pluripotent Stem Cells as a Promising Therapy for Infertility.

    PubMed

    Mouka, Aurélie; Tachdjian, Gérard; Dupont, Joëlle; Drévillon, Loïc; Tosca, Lucie

    2016-04-01

    Generation of gametes derived in vitro from pluripotent stem cells holds promising prospects for future reproductive applications. Indeed, it provides information on molecular and cellular mechanisms underlying germ cell (GC) development and could offer a new potential treatment for infertility. Great progress has been made in derivation of gametes from embryonic stem cells, despite ethical issues. Induced pluripotent stem cells (iPSCs) technology allows the reprogramming of a differentiated somatic cell, possibly emanating from the patient, into a pluripotent state. With the emergence of iPSCs, several studies created primordial GC stage to mature gamete-like cells in vitro in mice and humans. Recent findings in GC derivation suggest that in mice, functional gametes can be generated in vitro. This strengthens the idea that it might be possible in the future to generate functional human sperm and oocytes from pluripotent stem cells in culture.

  12. In Vitro Gamete Differentiation from Pluripotent Stem Cells as a Promising Therapy for Infertility.

    PubMed

    Mouka, Aurélie; Tachdjian, Gérard; Dupont, Joëlle; Drévillon, Loïc; Tosca, Lucie

    2016-04-01

    Generation of gametes derived in vitro from pluripotent stem cells holds promising prospects for future reproductive applications. Indeed, it provides information on molecular and cellular mechanisms underlying germ cell (GC) development and could offer a new potential treatment for infertility. Great progress has been made in derivation of gametes from embryonic stem cells, despite ethical issues. Induced pluripotent stem cells (iPSCs) technology allows the reprogramming of a differentiated somatic cell, possibly emanating from the patient, into a pluripotent state. With the emergence of iPSCs, several studies created primordial GC stage to mature gamete-like cells in vitro in mice and humans. Recent findings in GC derivation suggest that in mice, functional gametes can be generated in vitro. This strengthens the idea that it might be possible in the future to generate functional human sperm and oocytes from pluripotent stem cells in culture. PMID:26873432

  13. [Gamete donation contracts: gift of life or sale of genetic material?].

    PubMed

    Raposo, Vera Lúcia

    2012-01-01

    When science made possible to overcome the biological limitation to infertility, gamete had become a "valuable good". Therefore, lawyers are asked to define their juridical status, their modality of transference, their possible uses and the legal protection reserved to them.

  14. GENDER-SPECIFIC DIFFERENCES IN THE RESPONSE OF MATURING GAMETES TO TOXIC INSULT

    EPA Science Inventory

    GENDER-SPECIFIC DIFFERENCES IN THE RESPONSE OF MATURING GAMETES TO TOXIC INSULT

    Sally D. Perreault, U. S. Environmental Toxicology Division, National Health and Environmental Effects Research Laboratory, Reproductive Toxicology Division, Research Triangle Park, NC 27711

  15. Epigenetic effects of methoxychlor and vinclozolin on male gametes.

    PubMed

    Paoloni-Giacobino, Ariane

    2014-01-01

    Imprinting is an epigenetic form of gene regulation that mediates a parent-of-origin-dependent expression of the alleles of a number of genes. Imprinting, which occurs at specific sites within or surrounding the gene, called differentially methylated domains, consists in a methylation of CpGs. The appropriate transmission of genomics imprints is essential for the control of embryonic development and fetal growth. A number of endocrine disruptors (EDs) affect male reproductive tract development and spermatogenesis. It was postulated that the genetic effects of EDs might be induced by alterations in gene imprinting. We tested two EDs: methoxychlor and vinclozolin. Their administration during gestation induced in the offspring a decrease in sperm counts and significant modifications in the methylation pattern of a selection of paternally and maternally expressed canonical imprinted genes. The observation that imprinting was largely untouched in somatic cells suggests that EDs exert their damaging effects via the process of reprogramming that is unique to gamete development. Interestingly, the effects were transgenerational, although disappearing gradually from F1 to F3. A systematic analysis showed a heterogeneity in the CpG sensitivity to EDs. We propose that the deleterious effects of EDs on the male reproductive system are mediated by imprinting defects in the sperm. The reported effects of EDs on human male spermatogenesis might be mediated by analogous imprinting alterations.

  16. Keeping mum about dad: "contracts" to protect gamete donor anonymity.

    PubMed

    Rees, Anne

    2012-06-01

    This article considers the legal status of so-called contracts for anonymity between fertility clinics and donors of gametes that were made in the period before legislation authorising disclosure. It notes that while clinics frequently cite the existence of these "contracts" to argue against retrospective legislation authorising disclosure of the donor's identity, they may be nothing more than one-sided statements of informed consent. However, the article notes that even if an agreement between a donor and a clinic is not contractual, it does not follow that a person conceived through assisted reproductive technology has any right of access to the identity of the donor. The writer has not been able to locate examples of written promises by the clinics promising anonymity. There are written promises by the donors not to seek the identity of the recipients. These promises do not bind the resulting offspring nor do they appear to be supported by consideration. The article suggests that the basis for any individual donor to restrain a clinic from revealing their identity may be found in promissory estoppel. Nevertheless, there is no real issue in Australia concerning clinics revealing these details absent legislative authority. The issue is whether parliaments will legislate to authorise the disclosure. The article notes that it would be rare for parliaments to legislate to overturn existing legal contracts but suggests that the contract argument may not be as strong as has been thought.

  17. Oocyte transfer and gamete intrafallopian transfer in the mare.

    PubMed

    Carnevale, E M

    2004-07-01

    Methods for the collection and transfer of equine oocytes have been developed, and uses of these techniques have resulted in new clinical and research possibilities. Because oocyte transfer avoids reproductive problems associated with the oviduct, uterus, and cervix, pregnancies can be produced from many mares that cannot carry a pregnancy or produce embryos. Oocytes for clinical transfers are usually collected from preovulatory follicles and cultured for a short interval or transferred directly into a recipient's oviduct. For oocyte transfer, the recipient is inseminated within the uterus. A large number (1 x 10(9) to 2 x 10(9)) of motile sperms are preferred for inseminations. In contrast, sperm and oocyte are transferred into the oviduct during gamete intrafallopian transfer (GIFT). Therefore, a lower number (1 x 10(5) to 2 x 10(5)) of sperm can be used. Potentially, GIFT could be used in situations where sperm numbers are limited. Use of oocyte transfer and GIFT in clinical and research settings will aid us in understanding the interactions between oocyte, sperm, and oviduct in the equine. PMID:15271484

  18. Smoking and reproduction: gene damage to human gametes and embryos.

    PubMed

    Zenzes, M T

    2000-01-01

    Assisted conception is a useful methodology for detecting disturbances in clinical outcome, meiotic maturation, and genetic integrity of human gametes. Germinal cells are vulnerable to genetic damage from smoking, but can repair damage during meiosis. In ejaculated spermatozoa, repair capacity declines drastically. Smoking alters the meiotic spindle of oocytes and spermatozoa, leading to chromosome errors which affect reproductive outcomes. Smoking is associated with reduced numbers of retrieved oocytes, leading to early age of menopause. Oocyte elimination occurs preferentially during meiosis I, a period sensitive to genetic damage. Smoking inhibits embryo fragmentation; inhibition may confer survival advantage to embryos genetically altered. Smoking is associated with low sperm quality, but clinical effects are not recognized. Cadmium (a heavy metal), nicotine (a toxic alkaloid), and its metabolite cotinine, are detectable in gonadal tissues and fluids in association with smoking. Cotinine incorporates into ovarian granulosa-lutein cells, compromising the developmental potential of follicles. Benzo[a]pyrene is a carcinogenic polycyclic aromatic hydrocarbon resulting from cigarette combustion. Its reactive metabolite binds covalently to DNA, forming adducts. Smoking-related adducts were detectable in ovarian granulosa-lutein cells, oocytes, spermatozoa and preimplantation embryos. Transmission of altered DNA from smoking by spermatozoa was demonstrated in preimplantation embryos and in association with increased risk of childhood cancer. PMID:10782570

  19. High resistance of Acropora coral gametes facing copper exposure.

    PubMed

    Puisay, Antoine; Pilon, Rosanne; Hédouin, Laetitia

    2015-02-01

    Pollution by heavy metals remains today an important threat to the health of humans and ecosystems, but there is still a paucity of data on the response of early life stages of key organisms. In this context, the present work assessed the fertilization success rate of two Acropora species (A. cytherea and A. pulchra) from the French Polynesia reefs exposed to six increasing copper concentrations in seawater. The two species showed a relatively high tolerance to copper (4h30-EC50 was 69.4 ± 4.8 μg L(-1) and 75.4 ± 6.4 μg L(-1) for A. cytherea and A. pulchra, respectively). As Cu concentration increases, an increasing proportion of deformed embryos was recorded (67.6% and 58.5% for A. cytherea and A. pulchra, respectively, at 220 μg Cu L(-1)). These results demonstrated thus, that high levels of copper could negatively impair the normal fertilization process of coral gametes and therefore alter the renewal of coral populations. Since the two Acropora species investigated in this study displayed a high resistance to copper, these results should be considered in the context of multiple stressors associated with climate change, where rising temperature or ocean acidification may significantly exacerbate copper toxicity.

  20. New methods for gamete rescue from gonads of nondomestic felids.

    PubMed

    Jewgenow, K; Blottner, S; Lengwinat, T; Meyer, H H

    1997-01-01

    Methods for rescuing oocytes and spermatozoa post mortem are described, which were adapted from domestic cat as a model. Ovaries were mechanically processed for large-scale recovery of oocytes. Numbers of intact cumulus-oocyte complexes (COCs) per animal and of preantral follicles per ovary were 18 +/- 2 and 2892 +/- 665 in domestic cats, respectively. Similar results were obtained from 13 individuals of 6 nondomestic felids: 16 +/- 2 COCs and 1867 +/- 1144 follicles. Preantral follicles were cultured for at least 7 days. Intact COCs were maturated for 24 h and fertilized in vitro with homologous or heterologous (from domestic cat) spermatozoa. Spermatozoa were collected from caudae epididymides (n = 11; five nondomestic species) and cryopreserved (n = 8) using a programmed freezer. The reproductive competence of oocytes collected post mortem was demonstrated by development to embryos (> or = 8 cells) in vitro. Spermatogenic efficiency of males was assessed by flow cytometric analysis of mitotic and meiotic testicular cells as well as by estimation of testosterone concentration in testes. The results demonstrate the possibility of retrospective assessment of male and female reproductive capacity. In conclusion, the described methods could be a useful part of gamete rescue programmes for endangered felids. PMID:9404269

  1. Regulation of mouse gamete interaction by a sperm tyrosine kinase.

    PubMed

    Leyton, L; LeGuen, P; Bunch, D; Saling, P M

    1992-12-15

    A 95-kDa mouse sperm protein has been previously identified as a putative receptor involved in the sperm-egg interactions that lead to fertilization. The ligand for this receptor is the zona pellucida glycoprotein ZP3. This constituent of the oocyte-specific extracellular matrix mediates not only sperm binding to the zona but also triggers acrosomal exocytosis. The latter, also termed the acrosome reaction, is a key regulatory event upon which fertilization is absolutely dependent. Previously, we showed that the 95-kDa protein that binds ZP3 is a substrate for tyrosine kinase, and its phosphotyrosine content increases after sperm-zona pellucida binding. Here, we show the presence of protein tyrosine kinase activity in sperm plasma membranes and in electroeluted 95-kDa protein. The tyrosine kinase activity of the isolated protein is stimulated by solubilized zona pellucida and inhibited by tyrphostin RG-50864, a membrane-permeable tyrosine kinase inhibitor. Furthermore, tyrphostin inhibits zona-triggered acrosomal exocytosis in a dose-dependent manner. These findings indicate that the 95-kDa protein participates in a critical regulatory event of gamete interaction; moreover, our experiments suggest that sperm protein tyrosine kinase may be an excellent target for the control of fertility.

  2. Natural variation in epigenetic pathways affects the specification of female gamete precursors in Arabidopsis.

    PubMed

    Rodríguez-Leal, Daniel; León-Martínez, Gloria; Abad-Vivero, Ursula; Vielle-Calzada, Jean-Philippe

    2015-04-01

    In angiosperms, the transition to the female gametophytic phase relies on the specification of premeiotic gamete precursors from sporophytic cells in the ovule. In Arabidopsis thaliana, a single diploid cell is specified as the premeiotic female gamete precursor. Here, we show that ecotypes of Arabidopsis exhibit differences in megasporogenesis leading to phenotypes reminiscent of defects in dominant mutations that epigenetically affect the specification of female gamete precursors. Intraspecific hybridization and polyploidy exacerbate these defects, which segregate quantitatively in F2 populations derived from ecotypic hybrids, suggesting that multiple loci control cell specification at the onset of female meiosis. This variation in cell differentiation is influenced by the activity of ARGONAUTE9 (AGO9) and RNA-DEPENDENT RNA POLYMERASE6 (RDR6), two genes involved in epigenetic silencing that control the specification of female gamete precursors. The pattern of transcriptional regulation and localization of AGO9 varies among ecotypes, and abnormal gamete precursors in ovules defective for RDR6 share identity with ectopic gamete precursors found in selected ecotypes. Our results indicate that differences in the epigenetic control of cell specification lead to natural phenotypic variation during megasporogenesis. We propose that this mechanism could be implicated in the emergence and evolution of the reproductive alternatives that prevail in flowering plants.

  3. [Issues surrounding the preservation and subsequent use of transsexual persons' gametes].

    PubMed

    Jouannet, Pierre

    2014-03-01

    Some transsexual persons wish to have their gametes frozen before gender transition, in order to preserve their fertility. This measure should be carried out, in strict compliance with the law, in case of orchidectomy, oophorectomy or hysterectomy However, as hormonal treatments do not irreversibly alter gonadal function, the reproductive capacity of trans-sexual persons can be maintained by avoiding surgical sterilization. There is therefore no obvious medical indication for cryopreserving gametes or germinal tissue in the absence of surgical sterilization. Moreover, the use of such cryopreserved gametes would, in principle, be considered mainly by a same-sex couple, something that French law currently prohibits. Regardless of these legal aspects, the issues surrounding the use of cryopreserved gametes, and its consequences, must not be ignored. If transsexual persons who are already parents may find ways of managing the change in both their personal and parental identity, the use of gametes stored prior to gender transition raises issues of identity whose consequences are difficult to assess, especially for the future child. Cryopreservation of gametes or germinal tissue cannot be undertaken without first considering whether their potential use is in keeping with what is, at present, medically and legally possible. In any case, it is up the physician to decide, on a case by case basis, whether or not to implement cryopreservation, taking into account the situation of the persons who request the procedure and their plans for parenthood.

  4. Natural Variation in Epigenetic Pathways Affects the Specification of Female Gamete Precursors in Arabidopsis[OPEN

    PubMed Central

    Rodríguez-Leal, Daniel; León-Martínez, Gloria; Abad-Vivero, Ursula; Vielle-Calzada, Jean-Philippe

    2015-01-01

    In angiosperms, the transition to the female gametophytic phase relies on the specification of premeiotic gamete precursors from sporophytic cells in the ovule. In Arabidopsis thaliana, a single diploid cell is specified as the premeiotic female gamete precursor. Here, we show that ecotypes of Arabidopsis exhibit differences in megasporogenesis leading to phenotypes reminiscent of defects in dominant mutations that epigenetically affect the specification of female gamete precursors. Intraspecific hybridization and polyploidy exacerbate these defects, which segregate quantitatively in F2 populations derived from ecotypic hybrids, suggesting that multiple loci control cell specification at the onset of female meiosis. This variation in cell differentiation is influenced by the activity of ARGONAUTE9 (AGO9) and RNA-DEPENDENT RNA POLYMERASE6 (RDR6), two genes involved in epigenetic silencing that control the specification of female gamete precursors. The pattern of transcriptional regulation and localization of AGO9 varies among ecotypes, and abnormal gamete precursors in ovules defective for RDR6 share identity with ectopic gamete precursors found in selected ecotypes. Our results indicate that differences in the epigenetic control of cell specification lead to natural phenotypic variation during megasporogenesis. We propose that this mechanism could be implicated in the emergence and evolution of the reproductive alternatives that prevail in flowering plants. PMID:25829442

  5. Estimating exotic gene flow into native pine stands: zygotic vs. gametic components.

    PubMed

    Unger, G M; Vendramin, G G; Robledo-Arnuncio, J J

    2014-11-01

    Monitoring contemporary gene flow from widespread exotic plantations is becoming an important problem in forest conservation genetics. In plants, where both seed and pollen disperse, three components of exotic gene flow with potentially unequal consequences should be, but have not been, explicitly distinguished: zygotic, male gametic and female gametic. Building on a previous model for estimating contemporary rates of zygotic and male gametic gene flow among plant populations, we present here an approach that additionally estimates the third (female gametic) gene flow component, based on a combination of uni- and biparentally inherited markers. Using this method and a combined set of chloroplast and nuclear microsatellites, we estimate gene flow rates from exotic plantations into two Iberian relict stands of maritime pine (Pinus pinaster) and Scots pine (Pinus sylvestris). Results show neither zygotic nor female gametic gene flow but moderate (6-8%) male gametic introgression for both species, implying significant dispersal of pollen, but not of seeds, from exotic plantations into native stands shortly after introduced trees reached reproductive maturity. Numerical simulation results suggest that the model yields reasonably accurate estimates for our empirical data sets, especially for larger samples. We discuss conservation management implications of observed levels of exposure to nonlocal genes and identify research needs to determine potentially associated hazards. Our approach should be useful for plant ecologists and ecosystem managers interested in the vectors of contemporary genetic connectivity among discrete plant populations.

  6. Natural variation in epigenetic pathways affects the specification of female gamete precursors in Arabidopsis.

    PubMed

    Rodríguez-Leal, Daniel; León-Martínez, Gloria; Abad-Vivero, Ursula; Vielle-Calzada, Jean-Philippe

    2015-04-01

    In angiosperms, the transition to the female gametophytic phase relies on the specification of premeiotic gamete precursors from sporophytic cells in the ovule. In Arabidopsis thaliana, a single diploid cell is specified as the premeiotic female gamete precursor. Here, we show that ecotypes of Arabidopsis exhibit differences in megasporogenesis leading to phenotypes reminiscent of defects in dominant mutations that epigenetically affect the specification of female gamete precursors. Intraspecific hybridization and polyploidy exacerbate these defects, which segregate quantitatively in F2 populations derived from ecotypic hybrids, suggesting that multiple loci control cell specification at the onset of female meiosis. This variation in cell differentiation is influenced by the activity of ARGONAUTE9 (AGO9) and RNA-DEPENDENT RNA POLYMERASE6 (RDR6), two genes involved in epigenetic silencing that control the specification of female gamete precursors. The pattern of transcriptional regulation and localization of AGO9 varies among ecotypes, and abnormal gamete precursors in ovules defective for RDR6 share identity with ectopic gamete precursors found in selected ecotypes. Our results indicate that differences in the epigenetic control of cell specification lead to natural phenotypic variation during megasporogenesis. We propose that this mechanism could be implicated in the emergence and evolution of the reproductive alternatives that prevail in flowering plants. PMID:25829442

  7. Cell-cell signalling in sexual chemotaxis: a basis for gametic differentiation, mating types and sexes.

    PubMed

    Hadjivasiliou, Zena; Iwasa, Yoh; Pomiankowski, Andrew

    2015-08-01

    While sex requires two parents, there is no obvious need for them to be differentiated into distinct mating types or sexes. Yet this is the predominate state of nature. Here, we argue that mating types could play a decisive role because they prevent the apparent inevitability of self-stimulation during sexual signalling. We rigorously assess this hypothesis by developing a model for signaller-detector dynamics based on chemical diffusion, chemotaxis and cell movement. Our model examines the conditions under which chemotaxis improves partner finding. Varying parameter values within ranges typical of protists and their environments, we show that simultaneous secretion and detection of a single chemoattractant can cause a multifold movement impediment and severely hinder mate finding. Mutually exclusive roles result in faster pair formation, even when cells conferring the same roles cannot pair up. This arrangement also allows the separate mating types to optimize their signalling or detecting roles, which is effectively impossible for cells that are both secretors and detectors. Our findings suggest that asymmetric roles in sexual chemotaxis (and possibly other forms of sexual signalling) are crucial, even without morphological differences, and may underlie the evolution of gametic differentiation among both mating types and sexes.

  8. Cell–cell signalling in sexual chemotaxis: a basis for gametic differentiation, mating types and sexes

    PubMed Central

    Hadjivasiliou, Zena; Iwasa, Yoh; Pomiankowski, Andrew

    2015-01-01

    While sex requires two parents, there is no obvious need for them to be differentiated into distinct mating types or sexes. Yet this is the predominate state of nature. Here, we argue that mating types could play a decisive role because they prevent the apparent inevitability of self-stimulation during sexual signalling. We rigorously assess this hypothesis by developing a model for signaller–detector dynamics based on chemical diffusion, chemotaxis and cell movement. Our model examines the conditions under which chemotaxis improves partner finding. Varying parameter values within ranges typical of protists and their environments, we show that simultaneous secretion and detection of a single chemoattractant can cause a multifold movement impediment and severely hinder mate finding. Mutually exclusive roles result in faster pair formation, even when cells conferring the same roles cannot pair up. This arrangement also allows the separate mating types to optimize their signalling or detecting roles, which is effectively impossible for cells that are both secretors and detectors. Our findings suggest that asymmetric roles in sexual chemotaxis (and possibly other forms of sexual signalling) are crucial, even without morphological differences, and may underlie the evolution of gametic differentiation among both mating types and sexes. PMID:26156301

  9. Comparison of three replication strategies in complex multicellular organisms: Asexual replication, sexual replication with identical gametes, and sexual replication with distinct sperm and egg gametes

    NASA Astrophysics Data System (ADS)

    Tannenbaum, Emmanuel

    2008-01-01

    This paper studies the mutation-selection balance in three simplified replication models. The first model considers a population of organisms replicating via the production of asexual spores. The second model considers a sexually replicating population that produces identical gametes. The third model considers a sexually replicating population that produces distinct sperm and egg gametes. All models assume diploid organisms whose genomes consist of two chromosomes, each of which is taken to be functional if equal to some master sequence, and defective otherwise. In the asexual population, the asexual diploid spores develop directly into adult organisms. In the sexual populations, the haploid gametes enter a haploid pool, where they may fuse with other haploids. The resulting immature diploid organisms then proceed to develop into mature organisms. Based on an analysis of all three models, we find that, as organism size increases, a sexually replicating population can only outcompete an asexually replicating population if the adult organisms produce distinct sperm and egg gametes. A sexual replication strategy that is based on the production of large numbers of sperm cells to fertilize a small number of eggs is found to be necessary in order to maintain a sufficiently low cost for sex for the strategy to be selected for over a purely asexual strategy. We discuss the usefulness of this model in understanding the evolution and maintenance of sexual replication as the preferred replication strategy in complex, multicellular organisms.

  10. Gamete manipulation for development: new methods for conception.

    PubMed

    Yanagimachi, R

    2001-01-01

    Mammalian oocytes microsurgically injected with spermatozoa can develop into normal offspring. Apparently the oocyte has the ability to decompose or eliminate such sperm components as the plasma membrane and acrosomal contents, which normally do not enter its cytoplasm. Species in which normal offspring were obtained by direct sperm injection include: human, mouse, rabbit, horse, sheep, cattle, pig, and monkey. In the mouse, normal offspring can also be obtained routinely by the injection of round spermatid nuclei into oocytes. This suggests that all post-meiotic modifications of spermatozoa (spermiogenesis, sperm maturation, capacitation and the acrosome reaction) evolved as processes solely dedicated to delivering male genomes into female gametes. Birth of normal offspring after injection of spermatocytes into maturing or mature oocytes suggests that the mechanisms controlling meiosis of male and female germ cells are similar, if not the same. Spermatozoa do not need to be morphologically normal or alive in the conventional sense to participate in embryo development; as long as they have intact genomes, they are able to produce normal offspring. Chromosomes within the first and second polar bodies can be used as substitutes for female pronuclei for the production of normal offspring. The nuclei of adult somatic cells can be used for production of animals. This procedure, involving introduction of cell nuclei into enucleated oocytes (genomic cloning), is rather inefficient at present. Many obstacles must be overcome before it is accepted as a safe, novel method to reproduce scientifically, medically or economically valuable animals. For human cloning the prime consideration must be the welfare of the child. PMID:11545162

  11. [Gamete donor karyotyping: between real usefulness and safety rules].

    PubMed

    Siffroi, J-P

    2004-09-01

    The Commission de génétique de la Fédération française des CECOS has recently sent a questionnaire to each CECOS asking for the year of activity starting, the number of karyotypes performed every year, the number and the type of chromosomal abnormalities and the consequences for the donation process. For sperm donors, 9410 karyotypes have been realized during a mean number of 21.3 years. Fifty-seven chromosomal abnormalities (0.6%) have led to the exclusion of the donors, twenty of which being directly dangerous for the offspring [eight t(13;14), three reciprocal translocations, two structural abnormalities of unknown origin and seven inversions]. Twenty-three anomalies (three supernumerary markers, five 47,XYY, five fragile sites and ten mosaicism) as well as nine other (three Y chromosome inversions and six pericentric inversions of chromosome 9), although considered either as innocuous or as chromosomal variants, have also been excluded. Lastly, five miscellaneous abnormalities have also been considered as exclusion factors. Familial data and sperm counts were known for 28 of these donors. For egg donors, only 681 karyotypes have been performed during a mean number of 7.8 years of activity. Five karyotype abnormalities have led to the exclusion of the donor: one 47,XXX, one mosaicism 45,X/47,XXX/46,XX, one case of non specific rearrangements in half of mitosis and two reciprocal translocations [t(8;20) (q13;p13) et t(3;17) (q26;p13)]. The consequences of this study on gamete donor genetic screening are discussed. PMID:15380766

  12. Sperm competition and the evolution of gametic compatibility in externally fertilizing taxa.

    PubMed

    Kosman, E T; Levitan, D R

    2014-12-01

    Proteins expressed on the surface of sperm and egg mediate gametic compatibility and these proteins can be subject to intense positive selection. In this review, we discuss what is known about the patterns of adaptive evolution of gamete recognition proteins (GRPs). We focus on species that broadcast eggs and sperm into the environment for external fertilization, as the ease of observing and manipulating gamete interactions has allowed for greater advances in the understanding of GRP evolution, uncomplicated by confounding behavioral and physiological components that offer alternative evolutionary targets in internal fertilizers. We discuss whether interspecific mechanisms, such as selection to avoid fertilization between species (reinforcement selection), or intraspecific mechanisms, such as selection to increase (or decrease) the affinity between eggs and sperm based on the intensity of sperm competition, may be responsible for the pattern of GRP evolution observed. Variation in these proteins appears to influence gametic compatibility; GRP divergence among species is a better predictor of hybrid fertilization than neutral genetic markers and GRP variation within species predicts reproductive success among individuals within a population. Evidence suggests that sperm competition may play a large role in the evolution of gametic compatibility. PMID:25323969

  13. Gamete retrieval in terminal conditions: is it practical? What are the consequences?

    PubMed

    Finnerty, James J; Karns, Logan B; Thomas, Theodore S; West, Rebecca W; Pinkerton, JoAnn V

    2002-06-01

    There is an increasing interest in, and request for, gamete retrieval from recently deceased or near-dead subjects for the purpose of posthumous procreation. This usually arises in an emergency situation with little time for physicians to consider ethical ramifications. Advance planning is needed to help these physicians make thoughtful decisions. After considering the complexity of the issues involved, the Ethics Consult Service and the Ethics Committee at the University of Virginia requested that we develop a policy on gamete retrieval for subjects in terminal conditions, which would govern and guide involved providers should this process be requested. Our team consisted of members of the Ethics Consult Service and Ethics Committee, as well as personnel who might be intimately involved in the gamete retrieval process, including the director of the Human Gamete and Embryo Laboratory, a urologist, and a reproductive endocrinologist. In addition to reviewing the current literature describing the actual processes involved, we explored the ethical implications of gamete retrieval in these situations. A policy was developed and approved by the Ethics Committee at our institution, and is included in this article. PMID:12099192

  14. The meaning of synthetic gametes for gay and lesbian people and bioethics too.

    PubMed

    Murphy, Timothy F

    2014-11-01

    Some commentators indirectly challenge the ethics of using synthetic gametes as a way for same-sex couples to have children with shared genetics. These commentators typically impose a moral burden of proof on same-sex couples they do not impose on opposite-sex couples in terms of their eligibility to have children. Other commentators directly raise objections to parenthood by same-sex couples on the grounds that it compromises the rights and/or welfare of children. Ironically, the prospect of synthetic gametes neutralises certain of these objections, insofar as they would ensure that children have parents whom they can know as their genetic parents, which outcome is not always possible when same-sex couples involve third parties as the source of gametes or embryos. Not all commentators in bioethics throw the use of synthetic gametes into doubt as far as same-sex couples are concerned, but even these commentators put parenting by gay men and lesbians at the conclusion of an argument rather than presupposing parental legitimacy from the outset. Synthetic gametes do raise questions of ethics in regard to parenthood for gay men and lesbians, but these are largely questions of access and equity, not questions of parental fitness and/or child welfare.

  15. Gamete donor anonymity and limits on numbers of offspring: the views of three stakeholders

    PubMed Central

    Nelson, Margaret K.; Hertz, Rosanna; Kramer, Wendy

    2015-01-01

    This paper discusses the attitudes of three groups of stakeholders in the world of assisted reproduction gamete donors, parents who use donated gamete, and offspring conceived with donated gametes with respect to the two issues of donor anonymity and limits on the number of offspring a single donor can produce. The data are drawn from on-line surveys which were made available between May 12, 2104 and August 15, 2014 to gamete donors, donor-conceived offspring, and parents who used donated gametes to conceive. A total of 325 donors (176 egg donors; 149 sperm donors) responded to the survey as did 2134 parents and 419 offspring. The data show that offspring are more opposed to donor anonymity than are parents and donors. Among offspring opposition to anonymity grows as they age. On the other hand, parents are most in favor of limits on numbers of offspring produced by a single donor. Parents worry about health and accidental contact between people conceived from the same donor. PMID:27774232

  16. Conservation of DNA Methylation Programming Between Mouse and Human Gametes and Preimplantation Embryos.

    PubMed

    White, Carlee R; MacDonald, William A; Mann, Mellissa R W

    2016-09-01

    In mice, assisted reproductive technologies (ARTs) applied during gametogenesis and preimplantation development can result in disruption of genomic imprinting. In humans, these technologies and/or subfertility have been linked to perturbations in genomic imprinting. To understand how ARTs and infertility affect DNA methylation, it is important to understand DNA methylation dynamics and the role of regulatory factors at these critical stages. Recent genome studies performed using mouse and human gametes and preimplantation embryos have shed light onto these processes. Here, we comprehensively review the current state of knowledge regarding global and imprinted DNA methylation programming in the mouse and human. Available data highlight striking similarities in mouse and human DNA methylation dynamics during gamete and preimplantation development. Just as fascinating, these studies have revealed sex-, gene-, and allele-specific differences in DNA methylation programming, warranting future investigation to untangle the complex regulation of DNA methylation dynamics during gamete and preimplantation development.

  17. Purple sea urchin Strongylocentrotus purpuratus gamete manipulation using optical trapping and microfluidics

    NASA Astrophysics Data System (ADS)

    Chandsawangbhuwana, Charlie; Shi, Linda Z.; Zhu, Qingyuan; Berns, Michael W.

    2013-04-01

    A system has been developed that allows for optical and fluidic manipulation of gametes. The optical manipulation is performed by using a single-point gradient trap with a 40× oil immersion PH3 1.3 NA objective on a Zeiss inverted microscope. The fluidic manipulation is performed by using a custom microfluidic chamber designed to fit into the short working distance between the condenser and objective. The system is validated using purple sea urchin Strongylocentrotus purpuratus gametes and has the potential to be used for mammalian in vitro fertilization and animal husbandry.

  18. Salmonid Gamete Preservation in the Snake River Basin, Annual Report 2002.

    SciTech Connect

    Young, William; Kucera, Paul

    2003-07-01

    In spite of an intensive management effort, chinook salmon (Oncorhynchus tshawytscha) and steelhead (Oncorhynchus mykiss) populations in the Northwest have not recovered and are currently listed as threatened species under the Endangered Species Act. In addition to the loss of diversity from stocks that have already gone extinct, decreased genetic diversity resulting from genetic drift and inbreeding is a major concern. Reduced population and genetic variability diminishes the environmental adaptability of individual species and entire ecological communities. The Nez Perce Tribe (NPT), in cooperation with Washington State University and the University of Idaho, established a germplasm repository in 1992 in order to preserve the remaining salmonid diversity in the region. The germplasm repository provides long-term storage for cryopreserved gametes. Although only male gametes can be cryopreserved, conserving the male component of genetic diversity will maintain future management options for species recovery. NPT efforts have focused on preserving salmon and steelhead gametes from the major river subbasins in the Snake River basin. However, the repository is available for all management agencies to contribute gamete samples from other regions and species. In 2002 a total of 570 viable semen samples were added to the germplasm repository. This included the gametes of 287 chinook salmon from the Lostine River, Catherine Creek, upper Grande Ronde River, Imnaha River (Lookingglass Hatchery), Lake Creek, South Fork Salmon River, Johnson Creek, Big Creek, Capehorn Creek, Marsh Creek, Pahsimeroi River (Pahsimeroi Hatchery), and upper Salmon River (Sawtooth Hatchery) and the gametes of 280 steelhead from the North Fork Clearwater River (Dworshak Hatchery), Fish Creek, Little Sheep Creek, Pahsimeroi River (Pahsimeroi Hatchery) and Snake River (Oxbow Hatchery). In addition, gametes from 60 Yakima River spring chinook and 34 Wenatchee River coho salmon were added to the

  19. 2008 Guidelines for gamete and embryo donation: a Practice Committee report.

    PubMed

    2008-11-01

    The 2008 Guidelines for Gamete and Embryo Donation provide the latest recommendations for evaluation of potential sperm, oocyte, and embryo donors, incorporating recent information about optimal screening and testing for sexually transmitted infections (STIs), genetic diseases, and psychological assessments. This revised document incorporates recent information from the U.S. Centers for Disease Control and Prevention, the U.S. Food and Drug Administration, and the American Association of Tissue Banks, with which all programs offering gamete and embryo donation services must be thoroughly familiar. PMID:19007645

  20. Synthesis and Characterization of Th2N2(NH) Isomorphous to Th2N3

    SciTech Connect

    Silva, G W Chinthaka M; Yeamans, Charles B.; Hunn, John D; Sattelberger, Alfred P; Czerwinski, Ken R.; Weck, Dr. Phil F

    2012-01-01

    Using a new, low-temperature, fluoride-based process, thorium nitride imide of the chemical formula Th{sub 2}N{sub 2}(NH) was synthesized from thorium dioxide via an ammonium thorium fluoride intermediate. The resulting product phase was characterized by powder X-ray diffraction (XRD) analysis and was found to be crystallographically similar to Th{sub 2}N{sub 3}. Its unit cell was hexagonal with a space group of P3m{bar 1} and lattice parameters of a = b = 3.886(1) and c = 6.185(2) {angstrom}. The presence of -NH in the nitride phase was verified by Fourier transform infrared spectroscopy (FTIR). Total energy calculations performed using all-electron scalar relativistic density functional theory (DFT) showed that the hydrogen atom in the Th{sub 2}N{sub 2}(NH) prefers to bond with nitrogen atoms occupying 1a Wyckoff positions of the unit cell. Lattice fringe disruptions observed in nanoparticle areas of the nitride species by high-resolution transmission electron microscopic (HRTEM) images also displayed some evidence for the presence of -NH group. As ThO{sub 2} was identified as an impurity, possible reaction mechanisms involving its formation are discussed.

  1. 9 CFR 93.905 - Declaration and other documents for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... live fish, fertilized eggs, and gametes. 93.905 Section 93.905 Animals and Animal Products ANIMAL AND... (INCLUDING POULTRY) AND ANIMAL PRODUCTS IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN... Animal Species General Provisions for Svc-Regulated Fish Species § 93.905 Declaration and other...

  2. 9 CFR 93.905 - Declaration and other documents for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... live fish, fertilized eggs, and gametes. 93.905 Section 93.905 Animals and Animal Products ANIMAL AND... (INCLUDING POULTRY) AND ANIMAL PRODUCTS IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN... Animal Species General Provisions for Svc-Regulated Fish Species § 93.905 Declaration and other...

  3. 9 CFR 93.905 - Declaration and other documents for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... live fish, fertilized eggs, and gametes. 93.905 Section 93.905 Animals and Animal Products ANIMAL AND... (INCLUDING POULTRY) AND ANIMAL PRODUCTS IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN... Animal Species General Provisions for Svc-Regulated Fish Species § 93.905 Declaration and other...

  4. 9 CFR 93.905 - Declaration and other documents for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... live fish, fertilized eggs, and gametes. 93.905 Section 93.905 Animals and Animal Products ANIMAL AND... (INCLUDING POULTRY) AND ANIMAL PRODUCTS IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN... Animal Species General Provisions for Svc-Regulated Fish Species § 93.905 Declaration and other...

  5. 9 CFR 93.905 - Declaration and other documents for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... live fish, fertilized eggs, and gametes. 93.905 Section 93.905 Animals and Animal Products ANIMAL AND... (INCLUDING POULTRY) AND ANIMAL PRODUCTS IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN... Animal Species General Provisions for Svc-Regulated Fish Species § 93.905 Declaration and other...

  6. Selection in the Rapid Evolution of Gamete Recognition Proteins in Marine Invertebrates

    PubMed Central

    Vacquier, Victor D.; Swanson, Willie J.

    2011-01-01

    Animal fertilization is governed by the interaction (binding) of proteins on the surfaces of sperm and egg. In many examples presented herein, fertilization proteins evolve rapidly and show the signature of positive selection (adaptive evolution). This review describes the molecular evolution of fertilization proteins in sea urchins, abalone, and oysters, animals with external fertilization that broadcast their gametes into seawater. Theories regarding the selective forces responsible for the rapid evolution driven by positive selection seen in many fertilization proteins are discussed. This strong selection acting on divergence of interacting fertilization proteins might lead to prezygotic reproductive isolation and be a significant factor in the speciation process. Since only a fraction of all eggs are fertilized and only an infinitesimal fraction of male gametes succeed in fertilizing an egg, gametes are obviously a category of entities subjected to intense selection. It is curious that this is never mentioned in the literature dealing with selection, perhaps because we know so little about fitness differences among gametes.(ErnstMayr, 1997) PMID:21730046

  7. Experimental approach to prezygotic chromosome screening using only a single pair of gametes in mice

    PubMed Central

    WATANABE, Hiroyuki; KOHDA, Atsushi; TATENO, Hiroyuki

    2015-01-01

    During in vitro embryo production, chromosome screening is essential to prevent pregnancy losses caused by embryonic chromosome aberrations. When the chromosome screening is completed before fertilization, gametes are effectively utilized as genetic resources. The aim of this study was to investigate whether chromosome screening of gametes accompanied by fertilization would be feasible using a single mouse spermatozoon and oocyte. Metaphase II oocytes were divided into a cytoplast and a karyoplast. For genome cloning of the gametes, androgenic and gynogenic embryos were produced by microinjection of sperm into cytoplasts and parthenogenetic activation of karyoplasts, respectively. Pairs of blastomeres from androgenic and gynogenic embryos were fused electrically to produce diploid embryos, which were transferred into pseudopregnant surrogate mothers to examine fetal development. Blastomeres from androgenic and gynogenic embryos were individually treated with calyculin A—a specific inhibitor of type 1 and 2A protein phosphatases—for 2 h to induce premature chromosome condensation. Thereafter, chromosome analysis of blastomeres, reflecting the genetic constitution of individual spermatozoa and oocytes, was performed, and we confirmed that most of the androgenic and gynogenic 2-cell embryos had a haploid set of chromosomes in their sister blastomeres. The reconstructed embryos from blastomeres of androgenic and gynogenic 2-cell embryos could be implanted and develop into live fetuses, albeit at low efficiency. This study indicates that prezygotic chromosome screening and embryo production using a single pair of gametes may be practicable. PMID:26234555

  8. The ethics of anonymous gamete donation: is there a right to know one's genetic origins?

    PubMed

    De Melo-Martín, Inmaculada

    2014-01-01

    A growing number of jurisdictions hold that gamete donors must be identifiable to the children born with their eggs or sperm, on grounds that being able to know about one's genetic origins is a fundamental moral right. But the argument for that belief has not yet been adequately made.

  9. Salmonid Gamete Preservation in the Snake River Basin, 1998 Annual Report.

    SciTech Connect

    Armstrong, Robyn; Kucera, Paul A.

    1999-03-01

    Steelhead (Oncorhynchus mykiss) and salmon (Oncorhynchus tshawytscha)populations in the Northwest are decreasing. The Nez Perce Tribe (Tribe) was funded in 1998 by the Bonneville Power Administration to coordinate gene banking of male gametes from Endangered Species Act (ESA) listed steelhead and spring and summer chinook salmon in the Snake River basin.

  10. Gamete signalling underlies the evolution of mating types and their number.

    PubMed

    Hadjivasiliou, Zena; Pomiankowski, Andrew

    2016-10-19

    The gametes of unicellular eukaryotes are morphologically identical, but are nonetheless divided into distinct mating types. The number of mating types varies enormously and can reach several thousand, yet most species have only two. Why do morphologically identical gametes need to be differentiated into self-incompatible mating types, and why is two the most common number of mating types? In this work, we explore a neglected hypothesis that there is a need for asymmetric signalling interactions between mating partners. Our review shows that isogamous gametes always interact asymmetrically throughout sex and argue that this asymmetry is favoured because it enhances the efficiency of the mating process. We further develop a simple mathematical model that allows us to study the evolution of the number of mating types based on the strength of signalling interactions between gametes. Novel mating types have an advantage as they are compatible with all others and rarely meet their own type. But if existing mating types coevolve to have strong mutual interactions, this restricts the spread of novel types. Similarly, coevolution is likely to drive out less attractive mating types. These countervailing forces specify the number of mating types that are evolutionarily stable.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'. PMID:27619695

  11. Study of aneuploidy and DNA fragmentation in gametes of patients with severe teratozoospermia.

    PubMed

    Perrin, A; Louanjli, N; Ziane, Y; Louanjli, T; Le Roy, C; Gueganic, N; Amice, V; De Braekeleer, M; Morel, F

    2011-02-01

    This study investigated meiotic segregation in spermatozoa to determine if severe teratozoospermia should prevent the use of intracytoplasmic sperm injection (ICSI) because of the high production of gametes with chromosomal aneuploidies and analysed DNA fragmentation in gametes from the same semen to determine if DNA integrity was worse in patients with severe teratozoospermia. Sperm samples from 12 infertile patients were studied by fluorescence in-situ hybridization for chromosomes X, Y, 13, 18 and 21 and by TdT (terminal deoxynucleotidyl transferase)-mediated dUDP nick-end labelling. Four patients with a majority of macrocephalic forms with multiple flagella had more than 99% spermatozoa with abnormal chromosomal content. The other patients (globozoospermia or other abnormalities concerning sperm heads) had no increased aneuploidy or a slightly significant increase (P<0.05). The rate of DNA fragmentation was significantly higher in infertile patients than in the controls (P<0.001; 14.3% versus 1.20%, respectively) but presented important variability. Therefore, ICSI should not be attempted if men have macrocephalic gametes with multiple flagella but morphology is not always a good predictor of chromosomal content, depending upon the kind of teratozoospermia. Evaluation of the rate of aneuploidy and DNA fragmentation in gametes of patients with severe teratozoospermia is recommended.

  12. Gamete signalling underlies the evolution of mating types and their number

    PubMed Central

    Hadjivasiliou, Zena; Pomiankowski, Andrew

    2016-01-01

    The gametes of unicellular eukaryotes are morphologically identical, but are nonetheless divided into distinct mating types. The number of mating types varies enormously and can reach several thousand, yet most species have only two. Why do morphologically identical gametes need to be differentiated into self-incompatible mating types, and why is two the most common number of mating types? In this work, we explore a neglected hypothesis that there is a need for asymmetric signalling interactions between mating partners. Our review shows that isogamous gametes always interact asymmetrically throughout sex and argue that this asymmetry is favoured because it enhances the efficiency of the mating process. We further develop a simple mathematical model that allows us to study the evolution of the number of mating types based on the strength of signalling interactions between gametes. Novel mating types have an advantage as they are compatible with all others and rarely meet their own type. But if existing mating types coevolve to have strong mutual interactions, this restricts the spread of novel types. Similarly, coevolution is likely to drive out less attractive mating types. These countervailing forces specify the number of mating types that are evolutionarily stable. This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’. PMID:27619695

  13. INDUCED CYTOMICTIC VARIATIONS AND SYNCYTE FORMATION DURING MICROSPOROGENESIS IN PHASEOLUS VULGARIS L.

    PubMed

    Kumar, G; Chaudhary, N

    2016-01-01

    The intercellular translocation of chromatin material along with other cytoplasmic contents among the proximate meiocytes lying in close contact with each other commonly referred as cytomixis was reported during microsporogenesis in Phaseolus vulgaris L., a member of the family Fabaceae. The phenomenon of cytomixis was observed at three administered doses of gamma rays viz. 100, 200, 300 Gy respectively in the diploid plants of Phaseolus vulgaris L. The gamma rays irradiated plants showed the characteristic feature of inter-meiocyte chromatin/chromosomes transmigration through various means.such as channel formation, beak formation or by direct adhesion between the PMC's (Pollen mother cells). The present study also reports the first instance of syncyte formation induced via cytomictic transmigration in Phaseolus vulgaris L. Though the frequency of syncyteformation was rather low yet these could play a significant role in plant evolution. It is speculated that syncyte enhances the ploidy level of plants by forming 2n gametes and may lead to the production ofpolyploid plants. The phenomenon of cytomixis shows a gradual inclination along with the increasing treatment doses of gamma rays. The preponderance of cytomixis was more frequent during meiosis I as compared to meiosis II. An interesting feature noticed during the present study was the channel formation among the microspores and fusion among the tetrads due to cell wall dissolution. The impact of this phenomenon is also visible on the development of post-meiotic products. The formation of heterosized pollen grains; a deviation from the normal pollen grains has also been reported. The production of gametes with unbalanced chromosomes is of utmost importance and should be given more attention in future studies as they possess the capability of inducing variations at the genomic level and can be further utilized in the improvement of germplasm. PMID:27281925

  14. Heats of Formation for the Boronic Acids R–B(OH)2 and Boroxines R3B3O3 (R=H, Li, HBe, H2B, H3C, H2N, HO, F, and Cl) Calculated at the G2, G3, and G4 Levels of Theory

    PubMed Central

    Bock, Charles W.; Larkin, Joseph D.

    2014-01-01

    Boronic acids (R–B(OH)2) and their boroxine (R3B3O3) dehydration products have emerged as important classes of compounds with a multitude of diverse applications. However, the available heats of formation for these compounds are not always as accurate as would be required for further use. In this study the heats of formation at 298.15 K of R–B(OH)2 and R3B3O3 (R = H, Li, HBe, H2B, H3C, H2N, HO, F, and Cl) have been calculated at the G2, G3[G3B3], and G4 levels of theory and used to determine the enthalpy changes for the dehydration reactions: 3 R–B(OH)2 → R3B3O3 + 3 H2O; comparisons are made with other rigorous levels of theory, e.g. CBS-Q[CBS-QB3] and W1U, as well as with experimental values wherever possible. Enthalpy changes for the dehydration reactions have also been calculated using second-order Møller-Plesset perturbation theory (MP2) with the Dunning-Woon correlation-consistent aug-cc-pVDZ and aug-cc-pVTZ basis sets, and B3LYP density functional theory with the 6-311++G(2df,2pd) basis set. With the exception of H2N-B(OH)2, the dehydration reactions are consistently predicted to be exothermic. Our results provide a cautionary note for the use of the B3LYP functional in the calculation of structures and energies of boronic acids and boroxines. Where comparisons could be made, the G4 and W1U predictions for the heats of formation of these boron compounds differ significantly. PMID:24653975

  15. The category of Z2 n -supermanifolds

    NASA Astrophysics Data System (ADS)

    Covolo, Tiffany; Grabowski, Janusz; Poncin, Norbert

    2016-07-01

    In physics and in mathematics Z2 n -gradings, n ≥ 2, appear in various fields. The corresponding sign rule is determined by the "scalar product" of the involved Z2 n -degrees. The Z2 n -supergeometry exhibits challenging differences with the classical one: nonzero degree even coordinates are not nilpotent, and even (respectively, odd) coordinates do not necessarily commute (respectively, anticommute) pairwise. In this article we develop the foundations of the theory: we define Z2 n -supermanifolds and provide examples in the ringed space and coordinate settings. We thus show that formal series are the appropriate substitute for nilpotency. Moreover, the class of Z2 • -supermanifolds is closed with respect to the tangent and cotangent functors. We explain that any n-fold vector bundle has a canonical "superization" to a Z2 n -supermanifold and prove that the fundamental theorem describing supermorphisms in terms of coordinates can be extended to the Z2 n -context.

  16. Gene expression profiles in rice gametes and zygotes: identification of gamete-enriched genes and up- or down-regulated genes in zygotes after fertilization.

    PubMed

    Abiko, Mafumi; Maeda, Hiroki; Tamura, Kentaro; Hara-Nishimura, Ikuko; Okamoto, Takashi

    2013-04-01

    In angiosperms, fertilization and subsequent zygotic development occur in embryo sacs deeply embedded in the ovaries; therefore, these processes are poorly elucidated. In this study, microarray-based transcriptome analyses were conducted on rice sperm cells, egg cells, and zygotes isolated from flowers to identify candidate genes involved in gametic and/or early zygotic development. Cell type-specific transcriptomes were obtained, and up- or down-regulated genes in zygotes after fertilization were identified, in addition to genes enriched in male and female gametes. A total of 325 putatively up-regulated and 94 putatively down-regulated genes in zygotes were obtained. Interestingly, several genes encoding homeobox proteins or transcription factors were identified as highly up-regulated genes after fertilization, and the gene ontology for up-regulated genes was highly enriched in functions related to chromatin/DNA organization and assembly. Because a gene encoding methyltransferase 1 was identified as a highly up-regulated gene in zygotes after fertilization, the effect of an inhibitor of this enzyme on zygote development was monitored. The inhibitor appeared partially to affect polarity or division asymmetry in rice zygotes, but it did not block normal embryo generation.

  17. A Putative Small Solute Transporter Is Responsible for the Secretion of G377 and TRAP-Containing Secretory Vesicles during Plasmodium Gamete Egress and Sporozoite Motility

    PubMed Central

    Kehrer, Jessica; Singer, Mirko; Lemgruber, Leandro; Silva, Patricia A. G. C.; Frischknecht, Friedrich; Mair, Gunnar R.

    2016-01-01

    Regulated protein secretion is required for malaria parasite life cycle progression and transmission between the mammalian host and mosquito vector. During transmission from the host to the vector, exocytosis of highly specialised secretory vesicles, such as osmiophilic bodies, is key to the dissolution of the red blood cell and parasitophorous vacuole membranes enabling gamete egress. The positioning of adhesins from the TRAP family, from micronemes to the sporozoite surface, is essential for gliding motility of the parasite and transmission from mosquito to mammalian host. Here we identify a conserved role for the putative pantothenate transporter PAT in Plasmodium berghei in vesicle fusion of two distinct classes of vesicles in gametocytes and sporozoites. PAT is a membrane component of osmiophilic bodies in gametocytes and micronemes in sporozoites. Despite normal formation and trafficking of osmiophilic bodies to the cell surface upon activation, PAT-deficient gametes fail to discharge their contents, remain intraerythrocytic and unavailable for fertilisation and further development in the mosquito. Sporozoites lacking PAT fail to secrete TRAP, are immotile and thus unable to infect the subsequent rodent host. Thus, P. berghei PAT appears to regulate exocytosis in two distinct populations of vesicles in two different life cycle forms rather than acting as pantothenic transporter during parasite transmission. PMID:27427910

  18. Ethical aspects of creating human-nonhuman chimeras capable of human gamete production and human pregnancy.

    PubMed

    Palacios-González, César

    2015-01-01

    In this paper I explore some of the moral issues that could emerge from the creation of human-nonhuman chimeras (HNH-chimeras) capable of human gamete production and human pregnancy. First I explore whether there is a cogent argument against the creation of HNH-chimeras that could produce human gametes. I conclude that so far there is none, and that in fact there is at least one good moral reason for producing such types of creatures. Afterwards I explore some of the moral problems that could emerge from the fact that a HNH-chimera could become pregnant with a human conceptus. I focus on two sets of problems: problems that would arise by virtue of the fact that a human is gestated by a nonhuman creature, and problems that would emerge from the fact that such pregnancies could affect the health of the HNH-chimera.

  19. Incest, gamete donation by siblings and the importance of the genetic link.

    PubMed

    Pennings, G

    2002-01-01

    Recently, several requests have emerged in which women wished to be impregnated with donor eggs fertilized with spermatozoa of their brother. An important argument advanced against such applications is that it is a kind of incest. Four definitions of incest are reviewed in this article to evaluate the acceptability of these demands. The first three (sexual intercourse, reproduction with gametes of first-degree relatives and symbolic incest) do not apply to the cases. However, when the sister and her brother intend to raise the child as social mother and father, these requests should be considered as "intentional incest". If the brother only functions as an uncle, the request of the woman resembles the currently accepted practice of oocyte donation from sister to sister. In that case, the wish to receive gametes from a first-degree relative is motivated by the wish to establish as far as possible a genetic link with the child.

  20. Genome-wide profiling of DNA methylation and gene expression in Crassostrea gigas male gametes

    PubMed Central

    Olson, Claire E.; Roberts, Steven B.

    2014-01-01

    DNA methylation patterns and functions are variable across invertebrate taxa. In order to provide a better understanding of DNA methylation in the Pacific oyster (Crassostrea gigas), we characterized the genome-wide DNA methylation profile in male gamete cells using whole-genome bisulfite sequencing. RNA-Seq analysis was performed to examine the relationship between DNA methylation and transcript expression. Methylation status of over 7.6 million CpG dinucleotides was described with a majority of methylated regions occurring among intragenic regions. Overall, 15% of the CpG dinucleotides were determined to be methylated and the mitochondrial genome lacked DNA methylation. Integrative analysis of DNA methylation and RNA-Seq data revealed a positive association between methylation status, both in gene bodies and putative promoter regions, and expression. This study provides a comprehensive characterization of the distribution of DNA methylation in the oyster male gamete tissue and suggests that DNA methylation is involved in gene regulatory activity. PMID:24987376

  1. Preserved echinoderm gametes as a useful and ready-to-use bioassay material.

    PubMed

    Kiyomoto, M; Hamanaka, G; Hirose, M; Yamaguchi, M

    2014-02-01

    Marine animals, and sea urchin species in particular, have several advantages for use in environmental research. However, the spawned eggs of the sea urchin quickly lose fertility, although the fertile period can be lengthened by the addition of antibiotics to the sea water (Epel et al., 2004). We evaluated five species of Japanese sea urchin and the gametes of Hemicentrotus pulcherrimus could be maintained for 2 weeks or more at low temperature with the addition of antibiotics to sea water. We also demonstrated the practicality of shipping these preserved gametes as experimental material for universities and schools to use immediately for bioassays of physical and chemical impacts on the marine environment. PMID:24129269

  2. MORPHOLOGY OF GAMETE MEMBRANE FUSION AND OF SPERM ENTRY INTO OOCYTES OF THE SEA URCHIN

    PubMed Central

    Franklin, Luther E.

    1965-01-01

    Sea urchin gametes predominate in molecular studies of fertilization, yet relatively little is known of the subcellular aspects of sperm entry in this group. Accordingly, it seemed desirable to make a detailed examination of sperm entry phenomena in sea urchins with the electron microscope. Gametes of the sea urchins Arbacia punctulata and Lytechinus variegatus were used in this study. Samples of eggs containing 2 to 8 per cent oocytes were selected and fixed with osmium tetroxide in sea water at various intervals after insemination. Fixed specimens were embedded in Epon 812, sectioned, and examined with an electron microscope. An apical vesicle was observed at the anterior end of the acrosome. The presence of this structure, together with other observations, suggested that initiation of the acrosome reaction in sea urchin sperm involves dehiscence of the acrosomal region with the subsequent release of the acrosomal granule. Contact and initial fusion of gamete membranes was observed in mature eggs and oocytes and invariably involved the extended acrosomal tubule of the spermatozoon. Only one spermatozoon normally enters the mature egg. The probability of locating such a sperm in ultrathin sections is exceedingly low. Several sperm do normally enter oocytes. Consequently, observations of sperm entry were primarily restricted to the latter. The manner of sperm entry into oocytes did not resemble phagocytosis. Organelles of the spermatozoon were progressively divested of their plasma membrane as they entered the ground cytoplasm of the oocyte fertilization cone. Initiation of the acrosome reaction, contact and initial fusion of gamete membranes, and sperm entry into oocytes of sea urchins conform to the Hydroides-Saccoglossus pattern of early fertilization events as described by Colwin and Colwin (13). PMID:19866669

  3. The functional domain of GCS1-based gamete fusion resides in the amino terminus in plant and parasite species.

    PubMed

    Mori, Toshiyuki; Hirai, Makoto; Kuroiwa, Tsuneyoshi; Miyagishima, Shin-ya

    2010-01-01

    Fertilization is one of the most important processes in all organisms utilizing sexual reproduction. In a previous study, we succeeded in identifying a novel male gametic transmembrane protein GCS1 (GENERATIVE CELL SPECIFIC 1), also called HAP2 (HAPLESS 2) in the male-sterile Arabidopsis thaliana mutants, as a factor critical to gamete fusion in flowering plants. Interestingly, GCS1 is highly conserved among various eukaryotes covering plants, protists and invertebrates. Of these organisms, Chlamydomonas (green alga) and Plasmodium (malaria parasite) GCS1s similarly show male gametic expression and gamete fusion function. Since it is generally believed that protein factors controlling gamete fusion have rapidly evolved and different organisms utilize species-specific gamete fusion factors, GCS1 may be an ancient fertilization factor derived from the common ancestor of those organisms above. And therefore, its molecular structure and function are important to understanding the common molecular mechanics of eukaryotic fertilization. In this study, we tried to detect the central functional domain(s) of GCS1, using complementation assay of Arabidopsis GCS1 mutant lines expressing modified GCS1. As a result, the positively-charged C-terminal sequence of this protein is dispensable for gamete fusion, while the highly conserved N-terminal domain is critical to GCS1 function. In addition, in vitro fertilization assay of Plasmodium berghei (mouse malaria parasite) knock-in lines expressing partly truncated GCS1 showed similar results. Those findings above indicate that the extracellular N-terminus alone is sufficient for GCS1-based gamete fusion.

  4. Reprotoxicity of gold, silver, and gold-silver alloy nanoparticles on mammalian gametes.

    PubMed

    Tiedemann, Daniela; Taylor, Ulrike; Rehbock, Christoph; Jakobi, Jurij; Klein, Sabine; Kues, Wilfried A; Barcikowski, Stephan; Rath, Detlef

    2014-03-01

    Metal and alloy nanoparticles are increasingly developed for biomedical applications, while a firm understanding of their biocompatibility is still missing. Various properties have been reported to influence the toxic potential of nanoparticles. This study aimed to assess the impact of nanoparticle size, surface ligands and chemical composition of gold, silver or gold-silver alloy nanoparticles on mammalian gametes. An in vitro assay for porcine gametes was developed, since these are delicate primary cells, for which well-established culture systems exist and functional parameters are defined. During coincubation with oocytes for 46 h neither any of the tested gold nanoparticles nor the gold-silver alloy particles with a silver molar fraction of up to 50% showed any impact on oocyte maturation. Alloy nanoparticles with 80% silver molar fraction and pure silver nanoparticles inhibited cumulus-oocyte maturation. Confocal microscopy revealed a selective uptake of gold nanoparticles by oocytes, while silver and alloy particles mainly accumulated in the cumulus cell layer surrounding the oocyte. Interestingly sperm vitality parameters (motility, membrane integrity and morphology) were not affected by any of the tested nanoparticles. Only sporadic association of nanoparticles with the sperm plasma membrane was found by transmission electron microscopy. In conclusion, mammalian oocytes were sensitive to silver containing nanoparticles. Likely, the delicate process of completing meiosis in maternal gametes features high vulnerability towards nanomaterial derived toxicity. The results imply that released Ag(+)-ions are responsible for the observed toxicity, but the compounding into an alloy seemed to alleviate the toxic effects to a certain extent.

  5. Making Muslim babies: IVF and gamete donation in Sunni versus Shi'a Islam.

    PubMed

    Inhorn, Marcia C

    2006-12-01

    Medical anthropological research on science, biotechnology, and religion has focused on the "local moral worlds" of men and women as they make difficult decisions regarding their health and the beginnings and endings of human life. This paper focuses on the local moral worlds of infertile Muslims as they attempt to make, in the religiously correct fashion, Muslim babies at in vitro fertilization (IVF) clinics in Egypt and Lebanon. As early as 1980, authoritative fatwas issued from Egypt's famed Al-Azhar University suggested that IVF and similar technologies are permissible as long as they do not involve any form of third-party donation (of sperm, eggs, embryos, or uteruses). Since the late 1990s, however, divergences in opinion over third-party gamete donation have occurred between Sunni and Shi'ite Muslims, with Iran's leading ayatollah permitting gamete donation under certain conditions. This Iranian fatwa has had profound implications for the country of Lebanon, where a Shi'ite majority also seeks IVF services. Based on three periods of ethnographic research in Egyptian and Lebanese IVF clinics, this paper explores official and unofficial religious discourses surrounding the practice of IVF and third-party donation in the Muslim world, as well as the gender implications of gamete donation for Muslim marriages. PMID:17051430

  6. Chemically moderated gamete preferences predict offspring fitness in a broadcast spawning invertebrate

    PubMed Central

    Oliver, Mathew; Evans, Jonathan P.

    2014-01-01

    Sperm chemoattraction, where sperm locate unfertilized eggs by following a concentration gradient of egg-derived chemoattractants, has been widely documented across numerous taxa. While marine invertebrates are favoured models for understanding the underlying mechanisms of sperm chemoattraction, the evolutionary forces underpinning the process remain enigmatic. Here, we show that in mussels (Mytilus galloprovincialis), chemically moderated gamete preferences promote assortative fertilizations between genetically compatible gametes. When offered the choice of egg clutches from two females, sperm exhibited consistent but differential ‘preferences’ for chemical cues secreted from conspecific eggs. Critically, our data reveal that the preferences shown by sperm during the egg-choice trials are highly predictive of early embryonic viability when eggs and sperm from the same individuals are mixed during standard (no-choice) fertilization assays. Moreover, we demonstrate that by experimentally separating chemoattractants from eggs, sperm swimming behaviour is differentially regulated by egg-derived chemoattractants, and that these changes in sperm behaviour are highly consistent with observed patterns of gamete preferences, fertilization and larval survival. Together, this integrated series of experiments reveals that the behaviour of sperm is fine-tuned to respond differentially to the chemical signals emitted from different conspecific eggs, and that these choices have measurable fitness benefits. PMID:24741014

  7. Counselling on disclosure of gamete donation to donor offspring: a search for facts

    PubMed Central

    Visser, M.; Kop, P.A.L.; van Wely, M.; van der Veen, F.; Gerrits, G.J.E.; van Zwieten, M.C.B.

    2012-01-01

    Background: High quality counseling of potential parents is needed in the process of disclosure to donor offspring, which is important for the child and for family relationships. We performed a search for facts to identify the role of counseling in couples undergoing gamete donation. Methods: We systematically searched Pubmed, EMBASE and Psychinfo. Studies were included if they reported on counseling in gamete donation. Results: A total of 20 studies were included. Twelve studies stated that counselling was offered. The reported studies reflected no consensus about when and how counselling in gamete donation should be offered and no theoretical background of the disclosure/ secrecy issue. About 50% of the parents expressed the need for guidance and support of a counsellor. Special concerns were the disclosure issue and the future contact with the donor. Parents did not receive the guidance and support they needed in the disclosure process after treatment. Conclusion: Empirical knowledge on counselling is lacking. This review demonstrates the need to know more precisely at what moments couples should be counselled, and which specific information and guidelines couples need to receive to be more confident in the disclosure process to donor offspring. PMID:24753905

  8. Photoprotective effect of coumarin and 3-hydroxycoumarin in sea urchin gametes and embryonic cells.

    PubMed

    de Araujo Leite, Jocelmo Cássio; de Castro, Tainá Myra Xavier; Barbosa-Filho, José Maria; de Siqueira-Junior, José Pinto; Marques-Santos, Luis Fernando

    2015-05-01

    Ultraviolet radiation B (UVB) represents 5% of all solar UV radiation and chronic exposure can induce harmful biological responses, including skin cancer. Prospection of new drugs with photoprotective properties and less toxic effects is constant and natural products have been the main options in this field. Coumarins are a group of natural phenolic compounds that shows several pharmacological activities. The aim of present work was to investigate the effect of coumarin and six derivatives in sea urchin gametes and zygotes exposed to UVB. Embryonic development assay was used to monitor UVB embryotoxicity. Firstly, we demonstrated that coumarin inhibited first embryonic cell division from 5 μM (EC50 = 52.9 μM) and its derivatives showed an embryotoxic effect ten times higher. Then, gametes or zygotes were treated with coumarin compounds before or after UVB exposure (UVB doses ranged from 0.056 to 0.9 kJm(-2)). Pretreatment of gametes or zygotes with coumarin or 3-hydroxycoumarin (1 μM, both) decreased UVB embryotoxic effect. Protective effect of the compounds was observed only when cells were treated previous to UVB exposure. Coumarin derivatives 4-hydroxycoumarin, 6-hydroxycoumarin, 7-hydroxycoumarin, 6,7-dihydroxycoumarin and 6-methoxy-7-hydroxycoumarin did not exhibit photoprotective activity. Our data provides evidences that coumarin and 3-hydroxycoumarin can be a promising class of photoprotective drugs.

  9. Pheromonal stimulation of spawning release of gametes by gonadotropin releasing hormone in the chiton, Mopalia sp.

    PubMed

    Gorbman, Aubrey; Whiteley, Arthur; Kavanaugh, Scott

    2003-03-01

    The chiton Mopalia sp., a mollusc, was exposed to various dilutions of gonadotropin releasing hormone (GnRH) in sea water to determine whether this peptide is capable of acting as a pheromone that could stimulate release of ripe gametes (spawning). Two of the peptides, lamprey GnRH-1 and tunicate GnRH-2, had this action at a higher concentration (1.0 mg/L) but dilutions to 50 microg/L no longer were effective. Three other GnRHs: lamprey GnRH-3, tunicate GnRH-1, and a modified chicken GnRH-2, had no such action under the same test conditions. Since the spawning response could be produced by some GnRHs and not by others, it would appear that some kind of molecular recognition is involved, possibly by specific binding to a receptor. In earlier preliminary experiments tunicate GnRH-2 rapidly stimulated gamete release in a hemichordate, Saccoglossus. Thus it is suggested that GnRHs, in at least some invertebrates, may function as pheromones, serving to stimulate simultaneous spawning of individuals in a population of animals, and in this way assure more successful fertilization in species that must release their gametes into the water in which they live.

  10. Making muslim babies: Ivf and gamete donation in sunni versus shi’a islam

    PubMed Central

    2006-01-01

    Medical anthropological research on science, biotechnology, and religion has focused on the “local moral worlds” of men and women as they make difficult decisions regarding their health and the beginnings and endings of human life. This paper focuses on the local moral worlds of infertile Muslims as they attempt to make, in the religiously correct fashion, Muslim babies at in vitro fertilization (IVF) clinics in Egypt and Lebanon. As early as 1980, authoritative fatwas issued from Egypt’s famed Al-Azhar University suggested that IVF and similar technologies are permissible as long as they do not involve any form of third-party donation (of sperm, eggs, embryos, or uteruses). Since the late 1990s, however, divergences in opinion over third-party gamete donation have occurred between Sunni and Shi’ite Muslims, with Iran’s leading ayatollah permitting gamete donation under certain conditions. This Iranian fatwa has had profound implications for the country of Lebanon, where a Shi’ite majority also seeks IVF services. Based on three periods of ethnographic research in Egyptian and Lebanese IVF clinics, this paper explores official and unofficial religious discourses surrounding the practice of IVF and third-party donation in the Muslim world, as well as the gender implications of gamete donation for Muslim marriages. PMID:17051430

  11. Globalization and gametes: reproductive 'tourism,' Islamic bioethics, and Middle Eastern modernity.

    PubMed

    Inhorn, Marcia C

    2011-04-01

    'Reproductive tourism' has been defined as the search for assisted reproductive technologies (ARTs) and human gametes (eggs, sperm, embryos) across national and international borders. This article conceptualizes reproductive tourism within 'global reproscapes,' which involve the circulation of actors, technologies, money, media, ideas, and human gametes, all moving in complicated manners across geographical landscapes. Focusing on the Muslim countries of the Middle East, the article explores the Islamic 'local moral worlds' informing the movements of Middle Eastern infertile couples. The ban on third-party gamete donation in Sunni Muslim-majority countries and the recent allowance of donor technologies in the Shia Muslim-majority countries of Iran and Lebanon have led to significant movements of infertile couples across Middle Eastern national borders. In the new millennium, Iran is leading the way into this 'brave new world' of high-tech, third-party assisted conception, with Islamic bioethical discourses being used to justify various forms of technological assistance. Although the Middle East is rarely regarded in this way, it is a key site for understanding the intersection of technoscience, religious morality, and modernity, all of which are deeply implicated in the new world of reproductive tourism. PMID:21563005

  12. Female and male gamete mitochondria are distinct and complementary in transcription, structure, and genome function.

    PubMed

    de Paula, Wilson B M; Agip, Ahmed-Noor A; Missirlis, Fanis; Ashworth, Rachel; Vizcay-Barrena, Gema; Lucas, Cathy H; Allen, John F

    2013-01-01

    Respiratory electron transport in mitochondria is coupled to ATP synthesis while generating mutagenic oxygen free radicals. Mitochondrial DNA mutation then accumulates with age, and may set a limit to the lifespan of individual, multicellular organisms. Why is this mutation not inherited? Here we demonstrate that female gametes-oocytes-have unusually small and simple mitochondria that are suppressed for DNA transcription, electron transport, and free radical production. By contrast, male gametes-sperm-and somatic cells of both sexes transcribe mitochondrial genes for respiratory electron carriers and produce oxygen free radicals. This germ-line division between mitochondria of sperm and egg is observed in both the vinegar fruitfly and the zebrafish-species spanning a major evolutionary divide within the animal kingdom. We interpret these findings as an evidence that oocyte mitochondria serve primarily as genetic templates, giving rise, irreversibly and in each new generation, to the familiar energy-transducing mitochondria of somatic cells and male gametes. Suppressed mitochondrial metabolism in the female germ line may therefore constitute a mechanism for increasing the fidelity of mitochondrial DNA inheritance.

  13. Effects of Cadmium and Zinc on the Gamete Viability, Fertilization, and Embryonic Development of Tripneustes gratilla (Linnaeus)

    PubMed Central

    Tualla, Ivan Patrick B.; Bitacura, Jayzon G.

    2016-01-01

    Heavy metals are frequently reported for their mutagenic and teratogenic effects on benthic organisms. Thus, this study aimed to determine the toxicity of cadmium (Cd) and zinc (Zn) in the gametes of T. gratilla and to compare its fertilization and embryonic development under the highest nongametotoxic concentrations of these heavy metals. Gamete viability of T. gratilla under CdCl2 and ZnSO4 treatments was assayed through resazurin reduction test (RRT) and was confirmed through gamete morphology assay. ZnSO4 was more toxic to T. gratilla gametes than CdCl2 and egg cells were more sensitive to both than the sperm cells. Higher concentrations of CdCl2 and ZnSO4 induced gamete apoptosis and necrosis while highest nongametotoxic concentrations were determined at 1 × 10−3 M and 1 × 10−4 M, respectively, and were used in an in vitro fertilization and embryonic development experiment. ZnSO4 treatment inhibited fertilization more than CdCl2 and yielded more deformed embryos, while both induced abnormalities and hindered further embryonic development. This study gives the first report on the specific concentrations of Cd and Zn that are toxic to T. gratilla gametes and has confirmed the teratogenic effects of these heavy metals. PMID:27200213

  14. Aeronca C-2N Deluxe Scout

    NASA Technical Reports Server (NTRS)

    1936-01-01

    Aeronca C-2N Deluxe Scout: Known as the 'Flying Bathtub,' the portly Aeronca C-2N Deluxe Scout was used during Langley's research into the stability of light planes. Gust structure and intensity at low altitude was also investigated with the C-2. This particular C-2 still exists, as part of the collection of the Experimental Aircraft Association's Museum in Oshkosh, Wisconsin.

  15. The limits of evidence: evidence based policy and the removal of gamete donor anonymity in the UK.

    PubMed

    Frith, Lucy

    2015-03-01

    This paper will critically examine the use of evidence in creating policy in the area of reproductive technologies. The use of evidence in health care and policy is not a new phenomenon. However, codified strategies for evidence appraisal in health care technology assessments and attempts to create evidence based policy initiatives suggest that the way evidence is used in practice and policy has changed. This paper will examine this trend by considering what is counted as 'good' evidence, difficulties in translating evidence into policy and practice and how evidence interacts with principles. To illustrate these points the removal of gamete donor anonymity in the UK in 2005 and the debates that preceded this change in the law will be examined. It will be argued that evidence will only ever take us so far and attention should also be paid to the underlying principles that guide policy. The paper will conclude with suggestions for how underlying principles can be more rigorously used in policy formation. PMID:25743050

  16. Properties of Superconducting Mo, Mo2n and Trilayer Mo2n-Mo-Mo2n Thin Films

    NASA Technical Reports Server (NTRS)

    Barrentine, E. M.; Stevenson, T. R.; Brown, A. D.; Lowitz, A. E.; Noroozian, O.; U-Yen, K.; Eshan, N.; Hsieh, W. T.; Moseley, S. H.; Wollack, E. J.

    2014-01-01

    We present measurements of the properties of thin film superconducting Mo, Mo2N and Mo2N/Mo/Mo2N trilayers of interest for microwave kinetic inductance detector (MKID) applications. Using microwave resonator devices, we investigate the transition temperature, energy gaps, kinetic inductance, and internal quality factors of these materials. We present an Usadel-based interpretation of the trilayer transition temperature as a function of trilayer thicknesses, and a 2-gap interpretation to understand the change in kinetic inductance and internal resonance quality factor (Q) as a function of temperature.

  17. Formation of hydroxyl radicals and kinetic study of 2-chlorophenol photocatalytic oxidation using C-doped TiO2, N-doped TiO2, and C,N Co-doped TiO2 under visible light.

    PubMed

    Ananpattarachai, Jirapat; Seraphin, Supapan; Kajitvichyanukul, Puangrat

    2016-02-01

    This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH(•)), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N-doped TiO2, and C,N co-doped TiO2 prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy were used to analyze the titania. The rate of formation of OH(•) for each type of titania was determined, and the OH-index was calculated. The kinetics of as-synthesized TiO2 catalysts in photocatalytic oxidation of 2-chlorophenol (2-CP) under visible light irradiation were evaluated. Results revealed that nitrogen was incorporated into the lattice of titania with the structure of O-Ti-N linkages in N-doped TiO2 and C,N co-doped TiO2. Carbon was joined to the Ti-O-C bond in the C-doped TiO2 and C,N co-doped TiO2. The 2-CP adsorption ability of C,N co-doped TiO2 and C-doped TiO2 originated from a layer composed of a complex carbonaceous mixture at the surface of TiO2. C,N co-doped TiO2 had highest formation rate of OH(•) and photocatalytic activity due to a synergistic effect of carbon and nitrogen co-doping. The order of photocatalytic activity per unit surface area was the same as that of the formation rate of OH(•) unit surface area in the following order: C,N co-doped TiO2 > C-doped TiO2 > N-doped TiO2 > undoped TiO2.

  18. Lack of response to unaligned chromosomes in mammalian female gametes.

    PubMed

    Sebestova, Jaroslava; Danylevska, Anna; Novakova, Lucia; Kubelka, Michal; Anger, Martin

    2012-08-15

    Chromosome segregation errors are highly frequent in mammalian female meiosis, and their incidence gradually increases with maternal age. The fate of aneuploid eggs is obviously dependent on the stringency of mechanisms for detecting unattached or repairing incorrectly attached kinetochores. In case of their failure, the newly formed embryo will inherit the impaired set of chromosomes, which will have severe consequences for its further development. Whether spindle assembly checkpoint (SAC) in oocytes is capable of arresting cell cycle progression in response to unaligned kinetochores was discussed for a long time. It is known that abolishing SAC increases frequency of chromosome segregation errors and causes precocious entry into anaphase; SAC, therefore, seems to be essential for normal chromosome segregation in meiosis I. However, it was also reported that for anaphase-promoting complex (APC) activation, which is a prerequisite for entering anaphase; alignment of only a critical mass of kinetochores on equatorial plane is sufficient. This indicates that the function of SAC and of cooperating chromosome attachment correction mechanisms in oocytes is different from somatic cells. To analyze this phenomenon, we used live cell confocal microscopy to monitor chromosome movements, spindle formation, APC activation and polar body extrusion (PBE) simultaneously in individual oocytes at various time points during first meiotic division. Our results, using oocytes from aged animals and interspecific crosses, demonstrate that multiple unaligned kinetochores and severe congression defects are tolerated at the metaphase to anaphase transition, although such cells retain sensitivity to nocodazole. This indicates that checkpoint mechanisms, operating in oocytes at this point, are essential for accurate timing of APC activation in meiosis I, but they are insufficient in detection or correction of unaligned chromosomes, preparing thus conditions for propagation of the aneuploidy

  19. Lack of response to unaligned chromosomes in mammalian female gametes

    PubMed Central

    Sebestova, Jaroslava; Danylevska, Anna; Novakova, Lucia; Kubelka, Michal; Anger, Martin

    2012-01-01

    Chromosome segregation errors are highly frequent in mammalian female meiosis, and their incidence gradually increases with maternal age. The fate of aneuploid eggs is obviously dependent on the stringency of mechanisms for detecting unattached or repairing incorrectly attached kinetochores. In case of their failure, the newly formed embryo will inherit the impaired set of chromosomes, which will have severe consequences for its further development. Whether spindle assembly checkpoint (SAC) in oocytes is capable of arresting cell cycle progression in response to unaligned kinetochores was discussed for a long time. It is known that abolishing SAC increases frequency of chromosome segregation errors and causes precocious entry into anaphase; SAC, therefore, seems to be essential for normal chromosome segregation in meiosis I. However, it was also reported that for anaphase-promoting complex (APC) activation, which is a prerequisite for entering anaphase; alignment of only a critical mass of kinetochores on equatorial plane is sufficient. This indicates that the function of SAC and of cooperating chromosome attachment correction mechanisms in oocytes is different from somatic cells. To analyze this phenomenon, we used live cell confocal microscopy to monitor chromosome movements, spindle formation, APC activation and polar body extrusion (PBE) simultaneously in individual oocytes at various time points during first meiotic division. Our results, using oocytes from aged animals and interspecific crosses, demonstrate that multiple unaligned kinetochores and severe congression defects are tolerated at the metaphase to anaphase transition, although such cells retain sensitivity to nocodazole. This indicates that checkpoint mechanisms, operating in oocytes at this point, are essential for accurate timing of APC activation in meiosis I, but they are insufficient in detection or correction of unaligned chromosomes, preparing thus conditions for propagation of the aneuploidy

  20. A theoretical investigation into the strength of N-NO2 bonds, ring strain and electrostatic potential upon formation of intermolecular H-bonds between HF and the nitro group in nitrogen heterocyclic rings C n H2n N-NO2 (n = 2-5), RDX and HMX.

    PubMed

    Wang, Bao-Guo; Ren, Fu-de; Shi, Wen-Jing

    2015-11-01

    Changes in N-NO2 bond strength, ring strain energy and electrostatic potential upon formation of intermolecular H-bonds between HF and the nitro group in nitrogen heterocyclic rings C n H2n N-NO2 (n = 2-5), RDX and HMX were investigated using DFT-B3LYP and MP2(full) methods with the 6-311++G(2df,2p) and aug-cc-pVTZ basis sets. Analysis of electron density shifts was also carried out. The results indicate that H-bonding energy correlates well with the increment of ring strain energy. Upon complex formation, the strength of the N-NO2 trigger-bond is enhanced, suggesting reduced sensitivity, while judged by the increased ring strain energy, sensitivity is increased. However, some features of the molecular surface electrostatic potential, such as a local maximum above the N-NO2 bond and ring, σ + (2) and electrostatic balance parameter ν, remain essentially unchanged upon complex formation, and only a small change in the impact sensitivity h 50 is suggested. It is not sufficient to determine sensitivity solely on the basis of trigger bond or ring strain; as a global feature of a molecule, the molecular surface electrostatic potential is available to help judge the change of sensitivity in H-bonded complexes. Graphical Abstract The strengthened N-NO2 bond suggests reduced sensitivity, while it is reverse by theincreased ring strain energy upon the complex formation. However, the molecular surfaceelectrostatic potential (V S) shows the little change of h 50. The V S should be taken into accountin the analysis of explosive sensitivity in the H-bonded complex.

  1. [Treatment of long-term sterility by intra-tubal gamete transfer].

    PubMed

    Seifert, B; Hoppe, I; Nickel, I; Mühlnickel, D; Kapitza, W; Karsten, U; Denck, D; Freese, C

    1988-01-01

    It is reported about a first successful program of gamete intra fallopian transfer (GIFT) as a supplement to intrauterine insemination and to in vitro fertilization (IVF). In 29 patients after HMG stimulation of the ovaries and laparoscopic aspiration of follicles recovered oocytes have been introduced together with prepared sperm via a special catheter directly into the ampulla of the oviduct. In 21 patients with different causes of infertility optimal stimulation conditions could be achieved. A pregnancy rate of 41.4% is the result of 29 GIFT events and 3 of them resulted in spontaneous term deliveries (10.3%).

  2. Oocyte banking for anticipated gamete exhaustion (AGE) is a preventive intervention, neither social nor nonmedical.

    PubMed

    Stoop, Dominic; van der Veen, Fulco; Deneyer, Michel; Nekkebroeck, Julie; Tournaye, Herman

    2014-05-01

    The scope of female fertility preservation through cryopreservation of oocytes or ovarian cortex has widened from mainly oncological indications to a variety of fertility-threatening conditions. So far, no specific universally accepted denomination name has been given to cryopreservation of oocytes or ovarian cortex for the prevention of age-related fertility decline. We argue that the commonly used phrases 'social' and 'nonmedical freezing' to denote the indication for cryopreservation are not entirely correct. We suggest 'AGE banking', as this has not only the advantage of being catchy but also depicts the exact indication for the strategy, anticipated gamete exhaustion.

  3. Oocyte banking for anticipated gamete exhaustion (AGE) is a preventive intervention, neither social nor nonmedical.

    PubMed

    Stoop, Dominic; van der Veen, Fulco; Deneyer, Michel; Nekkebroeck, Julie; Tournaye, Herman

    2014-05-01

    The scope of female fertility preservation through cryopreservation of oocytes or ovarian cortex has widened from mainly oncological indications to a variety of fertility-threatening conditions. So far, no specific universally accepted denomination name has been given to cryopreservation of oocytes or ovarian cortex for the prevention of age-related fertility decline. We argue that the commonly used phrases 'social' and 'nonmedical freezing' to denote the indication for cryopreservation are not entirely correct. We suggest 'AGE banking', as this has not only the advantage of being catchy but also depicts the exact indication for the strategy, anticipated gamete exhaustion. PMID:24631381

  4. The technology, law, and ethics of in vitro fertilization, gamete donation, and surrogate motherhood.

    PubMed

    Wasserman, D; Wachbroit, R

    1992-09-01

    This article examines some of the legal, ethical, and policy issues raised by the development and use of technologies for noncoital reproduction: gamete transfer and manipulation, in vitro fertilization, and zygote transfer and manipulation. After briefly describing these technologies, this article examines three closely related concerns raised by their introduction: (1) the effect of new technologies on the social understanding of parenthood and the legal regulation of the family; (2) the impact on women and children of a market in the material and services for producing children; and (3) the rights and interests involved in conflicts over the control and disposition of extrauterine embryos. PMID:1521422

  5. Assisted conception and South Asian communities in the UK: public perceptions of the use of donor gametes in infertility treatment.

    PubMed

    Culley, Lorraine; Hudson, Nicky; Rapport, Frances

    2013-03-01

    This paper explores 'public' attitudes to the use of donated gametes in infertility treatment amongst members of British South Asian communities in the UK. The study included 14 single-sex focus groups with a total of 100 participants of Indian, Pakistani and Bangladeshi origins in three English cities and 20 individual semi-structured interviews with key informants. It explores five themes from the data: childlessness and stigma; using sperm and using eggs; cultural connections; choosing gametes; religion and the use of donated gametes; and disclosure and the management of information. The paper demonstrates that the socio-cultural context of fertility treatment is highly relevant and those delivering services and those consulting the public need to be aware of cultural and gender differences. Third party assisted conception represents a challenge to received ideas of identity and has implications for social reproduction and kinship which go well beyond immediate conjugal relationships.

  6. Postcopulatory selection for dissimilar gametes maintains heterozygosity in the endangered North Atlantic right whale

    PubMed Central

    Frasier, T R; Gillett, R M; Hamilton, P K; Brown, M W; Kraus, S D; White, B N

    2013-01-01

    Although small populations are expected to lose genetic diversity through genetic drift and inbreeding, a number of mechanisms exist that could minimize this genetic decline. Examples include mate choice for unrelated mates and fertilization patterns biased toward genetically dissimilar gametes. Both processes have been widely documented, but the long-term implications have received little attention. Here, we combined over 25 years of field data with high-resolution genetic data to assess the long-term impacts of biased fertilization patterns in the endangered North Atlantic right whale. Offspring have higher levels of microsatellite heterozygosity than expected from this gene pool (effect size = 0.326, P < 0.011). This pattern is not due to precopulatory mate choice for genetically dissimilar mates (P < 0.600), but instead results from postcopulatory selection for gametes that are genetically dissimilar (effect size = 0.37, P < 0.003). The long-term implication is that heterozygosity has slowly increased in calves born throughout the study period, as opposed to the slight decline that was expected. Therefore, this mechanism represents a natural means through which small populations can mitigate the loss of genetic diversity over time. PMID:24223284

  7. Gametic synapses, nanotubes and sperm RNAs - Redefining the origin of maternal determinants.

    PubMed

    Kloc, Malgorzata; Kubiak, Jacek Z; Bilinski, Szczepan M

    2016-08-01

    The female germline cells, i.e., the oocytes/eggs, contain a subpopulation of unique organelles and molecules (RNA and proteins) collectively called "the maternal determinants" that are indispensable for the determination of cell fate in the developing embryo. Although it has been known for some time that somatic cells deliver low-molecular-weight molecules to the oocyte/egg, the paradigm has been that the larger molecules and organelles are synthesized by the female germline cells without input from the surrounding somatic cells. However, recent discoveries of novel types of intercellular connections such as gametic synapses and tunneling nanotubes, allowing the transfer of large, externally derived molecules to the oocyte/egg, may dismantle the paradigm of the transcriptional/translational self-containment of the female gamete and add novel and unexpected aspects to the origin and identity of maternal determinants. In addition, the discovery that sperm delivers various RNAs to the egg suggests that sperm may not only epigenetically modify the egg genome but also influence or modify information contained in the maternal determinants.

  8. Intrafallopian transfer of gametes and early stage embryos for in vivo culture in cattle.

    PubMed

    Wetscher, F; Havlicek, V; Huber, T; Gilles, M; Tesfaye, D; Griese, J; Wimmers, K; Schellander, K; Müller, M; Brem, G; Besenfelder, U

    2005-07-01

    It may be possible to avoid inadequate in vitro culture conditions by incubating gametes or embryos in the oviducts for a short time. Ideally, an optimized procedure should be devised, combining in vitro and in vivo systems, in order to achieve synchronization in cattle. We transferred gametes as well as embryos in various stages of development and placed them into the oviducts. Embryos were recovered on Day 7 by flushing of oviducts and uterine horns. Blastocyst rates were determined on Day 7 and on Day 8. Experimental designs included transfer of in vitro matured cumulus oocyte complexes into previously inseminated heifers (COCs group), transfer of in vitro matured COCs simultaneously with capacitated spermatozoa (GIFTs group), transfer of four to eight cell stage embryos developed in vitro after IVM/IVF (Cleaved Stages group) and a group of solely in vitro produced embryos (IVP control group). Our results indicate that in vivo culture of IVM/IVF embryos in the homologous bovine oviduct has a positive influence on subsequent pre-implantation development. In addition, we have evidence that in vitro maturation and in vivo fertilization cannot be synchronized. PMID:15935840

  9. Strategies for locating the female gamete: the importance of measuring sperm trajectories in three spatial dimensions.

    PubMed

    Guerrero, Adán; Carneiro, Jorge; Pimentel, Arturo; Wood, Christopher D; Corkidi, Gabriel; Darszon, Alberto

    2011-08-01

    The spermatozoon must find its female gamete partner and deliver its genetic material to generate a new individual. This requires that the spermatozoon be motile and endowed with sophisticated swimming strategies to locate the oocyte. A common strategy is chemotaxis, in which spermatozoa detect and follow a gradient of chemical signals released by the egg and its associated structures. Decoding the female gamete's positional information is a process that spermatozoa undergo in a three-dimensional (3D) space; however, due to their speed and small size, this process has been studied almost exclusively in spermatozoa restricted to swimming in two dimensions (2D). This review examines the relationship between the mechanics of sperm propulsion and the physiological function of these cells in 3D. It also considers whether it is possible to derive all the 3D sperm swimming characteristics by extrapolating from 2D measurements. It is concluded that full insight into flagellar beat dynamics, swimming paths and chemotaxis under physiological conditions will eventually require quantitative imaging of flagellar form, ion flux changes, cell trajectories and modelling of free-swimming spermatozoa in 3D.

  10. Intraspecific genetic analysis, gamete release performance, and growth of Sargassum muticum (Fucales, Phaeophyta) from China

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Pang, Shaojun; Gao, Suqin; Shan, Tifeng

    2013-11-01

    Sargassum muticum is one of the most abundant and conspicuous native macroalgae species on the northern coasts of China. It often forms large-scale seaweed beds in subtidal zones. This investigation was designed to understand the intraspecific genetic relationships of this alga based on samples collected from four northern coastal sites of China, and to evaluate gamete release and growth capacity in laboratory conditions. The nuclear internal transcribed spacer 2 (ITS2) sequences of 16 samples from four locations were identical. Based on cox3 gene and partial rbcLS operon sequences, intraspecific genetic variability was detected with three and two ribotypes, respectively. Temperature, not irradiance, was shown to significantly affect gamete release and fertilization. Elevated temperature and irradiance enhanced the growth of germlings and vegetative branchlets. Maximum growth rate of germlings was detected at 18-24°C and an irradiance of 60-100 μmol photons/(m2·s). Under ambient conditions (12-25°C and 60-125 μmol photons/(m2·s)), relative growth rate of young branchlets could reach 7.5%/d.

  11. Gametic synapses, nanotubes and sperm RNAs - Redefining the origin of maternal determinants.

    PubMed

    Kloc, Malgorzata; Kubiak, Jacek Z; Bilinski, Szczepan M

    2016-08-01

    The female germline cells, i.e., the oocytes/eggs, contain a subpopulation of unique organelles and molecules (RNA and proteins) collectively called "the maternal determinants" that are indispensable for the determination of cell fate in the developing embryo. Although it has been known for some time that somatic cells deliver low-molecular-weight molecules to the oocyte/egg, the paradigm has been that the larger molecules and organelles are synthesized by the female germline cells without input from the surrounding somatic cells. However, recent discoveries of novel types of intercellular connections such as gametic synapses and tunneling nanotubes, allowing the transfer of large, externally derived molecules to the oocyte/egg, may dismantle the paradigm of the transcriptional/translational self-containment of the female gamete and add novel and unexpected aspects to the origin and identity of maternal determinants. In addition, the discovery that sperm delivers various RNAs to the egg suggests that sperm may not only epigenetically modify the egg genome but also influence or modify information contained in the maternal determinants. PMID:27443627

  12. Triploid planarian reproduces truly bisexually with euploid gametes produced through a different meiotic system between sex.

    PubMed

    Chinone, Ayako; Nodono, Hanae; Matsumoto, Midori

    2014-06-01

    Although polyploids are common among plants and some animals, polyploidization often causes reproductive failure. Triploids, in particular, are characterized by the problems of chromosomal pairing and segregation during meiosis, which may cause aneuploid gametes and results in sterility. Thus, they are generally considered to reproduce only asexually. In the case of the Platyhelminthes Dugesia ryukyuensis, populations with triploid karyotypes are normally found in nature as both fissiparous and oviparous triploids. Fissiparous triploids can also be experimentally sexualized if they are fed sexual planarians, developing both gonads and other reproductive organs. Fully sexualized worms begin reproducing by copulation rather than fission. In this study, we examined the genotypes of the offspring obtained by breeding sexualized triploids and found that the offspring inherited genes from both parents, i.e., they reproduced truly bisexually. Furthermore, meiotic chromosome behavior in triploid sexualized planarians differed significantly between male and female germ lines, in that female germ line cells remained triploid until prophase I, whereas male germ line cells appeared to become diploid before entry into meiosis. Oocytes at the late diplotene stage contained not only paired bivalents but also unpaired univalents that were suggested to produce diploid eggs if they remained in subsequent processes. Triploid planarians may therefore form euploid gametes by different meiotic systems in female and male germ lines and thus are be able to reproduce sexually in contrast to many other triploid organisms. PMID:24402417

  13. Local gamete competition explains sex allocation and fertilization strategies in the sea.

    PubMed

    Henshaw, Jonathan M; Marshall, Dustin J; Jennions, Michael D; Kokko, Hanna

    2014-08-01

    Within and across taxa, there is much variation in the mode of fertilization, that is, whether eggs and/or sperm are released or kept inside or on the surface of the parent's body. Although the evolutionary consequences of fertilization mode are far-reaching, transitions in the fertilization mode itself have largely escaped theoretical attention. Here we develop the first evolutionary model of egg retention and release, which also considers transitions between hermaphroditism and dioecy as well as egg size evolution. We provide a unifying explanation for reported associations between small body size, hermaphroditism, and egg retention in marine invertebrates that have puzzled researchers for more than 3 decades. Our model, by including sperm limitation, shows that all these patterns can arise as an evolutionary response to local competition between eggs for fertilization. This can provide a general explanation for three empirical patterns: sperm casters tend to be smaller than related broadcast spawners, hermaphroditism is disproportionately common in sperm casters, and offspring of sperm casters are larger. Local gamete competition also explains a universal sexual asymmetry: females of some species retain their gametes while males release theirs, but the opposite ("egg casting") lacks evolutionary stability and is apparently not found in nature.

  14. Behavioural traits propagate across generations via segregated iterative-somatic and gametic epigenetic mechanisms.

    PubMed

    Mitchell, Emma; Klein, Shifra L; Argyropoulos, Kimon V; Sharma, Ali; Chan, Robin B; Toth, Judit Gal; Barboza, Luendreo; Bavley, Charlotte; Bortolozzi, Analia; Chen, Qiuying; Liu, Bingfang; Ingenito, Joanne; Mark, Willie; Dudakov, Jarrod; Gross, Steven; Di Paolo, Gilbert; Artigas, Francesc; van den Brink, Marcel; Toth, Miklos

    2016-01-01

    Parental behavioural traits can be transmitted by non-genetic mechanisms to the offspring. Although trait transmission via sperm has been extensively researched, epidemiological studies indicate the exclusive/prominent maternal transmission of many non-genetic traits. Since maternal conditions impact the offspring during gametogenesis and through fetal/early-postnatal life, the resultant phenotype is likely the aggregate of consecutive germline and somatic effects; a concept that has not been previously studied. Here, we dissected a complex maternally transmitted phenotype, reminiscent of comorbid generalized anxiety/depression, to elementary behaviours/domains and their transmission mechanisms in mice. We show that four anxiety/stress-reactive traits are transmitted via independent iterative-somatic and gametic epigenetic mechanisms across multiple generations. Somatic/gametic transmission alters DNA methylation at enhancers within synaptic genes whose functions can be linked to the behavioural traits. Traits have generation-dependent penetrance and sex specificity resulting in pleiotropy. A transmission-pathway-based concept can refine current inheritance models of psychiatric diseases and facilitate the development of better animal models and new therapeutic approaches.

  15. Gametic embryogenesis and haploid technology as valuable support to plant breeding.

    PubMed

    Germanà, Maria Antonietta

    2011-05-01

    Plant breeding is focused on continuously increasing crop production to meet the needs of an ever-growing world population, improving food quality to ensure a long and healthy life and address the problems of global warming and environment pollution, together with the challenges of developing novel sources of biofuels. The breeders' search for novel genetic combinations, with which to select plants with improved traits to satisfy both farmers and consumers, is endless. About half of the dramatic increase in crop yield obtained in the second half of the last century has been achieved thanks to the results of genetic improvement, while the residual advance has been due to the enhanced management techniques (pest and disease control, fertilization, and irrigation). Biotechnologies provide powerful tools for plant breeding, and among these ones, tissue culture, particularly haploid and doubled haploid technology, can effectively help to select superior plants. In fact, haploids (Hs), which are plants with gametophytic chromosome number, and doubled haploids (DHs), which are haploids that have undergone chromosome duplication, represent a particularly attractive biotechnological method to accelerate plant breeding. Currently, haploid technology, making possible through gametic embryogenesis the single-step development of complete homozygous lines from heterozygous parents, has already had a huge impact on agricultural systems of many agronomically important crops, representing an integral part in their improvement programmes. The aim of this review was to provide some background, recent advances, and future prospective on the employment of haploid technology through gametic embryogenesis as a powerful tool to support plant breeding.

  16. Postcopulatory selection for dissimilar gametes maintains heterozygosity in the endangered North Atlantic right whale.

    PubMed

    Frasier, T R; Gillett, R M; Hamilton, P K; Brown, M W; Kraus, S D; White, B N

    2013-09-01

    Although small populations are expected to lose genetic diversity through genetic drift and inbreeding, a number of mechanisms exist that could minimize this genetic decline. Examples include mate choice for unrelated mates and fertilization patterns biased toward genetically dissimilar gametes. Both processes have been widely documented, but the long-term implications have received little attention. Here, we combined over 25 years of field data with high-resolution genetic data to assess the long-term impacts of biased fertilization patterns in the endangered North Atlantic right whale. Offspring have higher levels of microsatellite heterozygosity than expected from this gene pool (effect size = 0.326, P < 0.011). This pattern is not due to precopulatory mate choice for genetically dissimilar mates (P < 0.600), but instead results from postcopulatory selection for gametes that are genetically dissimilar (effect size = 0.37, P < 0.003). The long-term implication is that heterozygosity has slowly increased in calves born throughout the study period, as opposed to the slight decline that was expected. Therefore, this mechanism represents a natural means through which small populations can mitigate the loss of genetic diversity over time. PMID:24223284

  17. Equivalence by descent: pedigree analysis with inbreeding and gametic phase disequilibrium.

    PubMed

    Denniston, C

    2000-01-01

    In the presence of gametic phase disequilibrium and inbreeding, multiple locus genotype frequencies cannot be written solely in terms of identity by descent (IBD) probabilities. Following Cockerham & Weir (1973) we introduce the concept of 'equivalence by descent' (EBD), an extension of the concept of IBD to include non-allelic genes. Two genes are said to be EBD if they derive ultimately from the same founding gamete of a pedigree. Allelic genes that are EBD are also IBD. For two loci 11 EBD probabilities, the 'J-coefficients,' are required and for three loci 117 J-coefficients are required to write genotype probabilities. It is shown how the 117 J-coefficients for three loci can be reduced to a basic set of 37. Computer programs, written in the algebraic programming language, MAPLE, are described which are capable of calculating the two- and three-locus J-coefficients for any pedigree, subject only to size limitations. The MAPLE packages are available from the author upon request.

  18. Behavioural traits propagate across generations via segregated iterative-somatic and gametic epigenetic mechanisms

    PubMed Central

    Mitchell, Emma; Klein, Shifra L.; Argyropoulos, Kimon V.; Sharma, Ali; Chan, Robin B.; Toth, Judit Gal; Barboza, Luendreo; Bavley, Charlotte; Bortolozzi, Analia; Chen, Qiuying; Liu, Bingfang; Ingenito, Joanne; Mark, Willie; Dudakov, Jarrod; Gross, Steven; Di Paolo, Gilbert; Artigas, Francesc; van den Brink, Marcel; Toth, Miklos

    2016-01-01

    Parental behavioural traits can be transmitted by non-genetic mechanisms to the offspring. Although trait transmission via sperm has been extensively researched, epidemiological studies indicate the exclusive/prominent maternal transmission of many non-genetic traits. Since maternal conditions impact the offspring during gametogenesis and through fetal/early-postnatal life, the resultant phenotype is likely the aggregate of consecutive germline and somatic effects; a concept that has not been previously studied. Here, we dissected a complex maternally transmitted phenotype, reminiscent of comorbid generalized anxiety/depression, to elementary behaviours/domains and their transmission mechanisms in mice. We show that four anxiety/stress-reactive traits are transmitted via independent iterative-somatic and gametic epigenetic mechanisms across multiple generations. Somatic/gametic transmission alters DNA methylation at enhancers within synaptic genes whose functions can be linked to the behavioural traits. Traits have generation-dependent penetrance and sex specificity resulting in pleiotropy. A transmission-pathway-based concept can refine current inheritance models of psychiatric diseases and facilitate the development of better animal models and new therapeutic approaches. PMID:27173585

  19. Developmental Coordination of Gamete Differentiation with Programmed Cell Death in Sporulating Yeast

    PubMed Central

    Eastwood, Michael D.

    2015-01-01

    The gametogenesis program of the budding yeast Saccharomyces cerevisiae, also known as sporulation, employs unusual internal meiotic divisions, after which all four meiotic products differentiate within the parental cell. We showed previously that sporulation is typically accompanied by the destruction of discarded immature meiotic products through their exposure to proteases released from the mother cell vacuole, which undergoes an apparent programmed rupture. Here we demonstrate that vacuolar rupture contributes to de facto programmed cell death (PCD) of the meiotic mother cell itself. Meiotic mother cell PCD is accompanied by an accumulation of depolarized mitochondria, organelle swelling, altered plasma membrane characteristics, and cytoplasmic clearance. To ensure that the gametes survive the destructive consequences of developing within a cell that is executing PCD, we hypothesized that PCD is restrained from occurring until spores have attained a threshold degree of differentiation. Consistent with this hypothesis, gene deletions that perturb all but the most terminal postmeiotic spore developmental stages are associated with altered PCD. In these mutants, meiotic mother cells exhibit a delay in vacuolar rupture and then appear to undergo an alternative form of PCD associated with catastrophic consequences for the underdeveloped spores. Our findings reveal yeast sporulation as a context of bona fide PCD that is developmentally coordinated with gamete differentiation. PMID:26092920

  20. Gamete derivation from stem cells: revisiting the concept of genetic parenthood.

    PubMed

    Mertes, Heidi

    2014-11-01

    Genetic parenthood is usually portrayed as a value-neutral concept that can be confirmed or rejected based on objective, scientific tests. However, on inspection, it is exposed as a very complex idea that we might need to consider as something that comes in different shapes and forms and that is open to interpretation rather than being clearly defined and fixed. Different people may therefore also desire different aspects of the general concept of genetic parenthood, which implies that some may not even be satisfied with gametes that have all the properties that their own natural gametes would have, whereas others may be satisfied with a much simpler solution. Encouraging infertility patients to gain insight into what it is exactly that they hope to gain by pursuing genetic parenthood (rather than choosing for donor conception or adoption) may lead them to recognise that the added advantage may be limited and may be acquired in other ways as well. Nevertheless, many people will find it difficult to let go of the desire for genetic parenthood as it is deeply rooted in our genes. Infertility is experienced as a grave medical condition and entails an intense grieving process for many. For that reason alone it is important that the medical and research community develop and apply methods to help people in their quest for genetic parenthood. On the other hand, it is important not to reinforce the dogma that genetic parenthood is 'the best kind of parenthood'.

  1. Gamete intra-fallopian transfer or intrauterine insemination after controlled ovarian hyperstimulation for treatment of infertility due to endometriosis.

    PubMed

    Lodhi, S; Abdel Fattah, A; Abozaid, T; Murphy, J; Formantini, E; Sasy, M; Barber, K; Abuzeid, M

    2004-09-01

    We compared the effectiveness of gamete intra-Fallopian transfer (GIFT) and intrauterine insemination (IUI) after controlled ovarian hyperstimulation (COH) in the treatment of infertility due to endometriosis. This was a retrospective study carried out at a tertiary teaching medical center. A total of 127 consecutive patients with endometriosis were treated with GIFT or IUI after COH between June 1990 and December 1998. Patients were divided into two groups. Group 1 (n = 97) included patients with stages 1 and 2 endometriosis, and group 2 (n = 30) included patients with stages 3 and 4 endometriosis. Laparoscopic conservative surgery for endometriosis was performed prior to IUI for patients in both group 1 and group 2. In group 1, 55 patients underwent 95 cycles of IUI after COH and 42 patients underwent 57 cycles of GIFT. In group 2, 14 patients underwent 16 cycles of IUI after COH, while 16 patients underwent 22 cycles of GIFT. The stimulation protocol for both GIFT and IUI was mid-luteal pituitary down-regulation with a gonadotropin releasing hormone agonist (GnRH-a) followed by gonadotropins. In group 1, the pregnancy rates (GIFT = 50.9%, IUI = 29.4%) and the delivery rates (GIFT = 28.1%, IUI = 14.7%) per cycle were significantly higher in GIFT compared to IUI (p = 0.009 and p = 0.05, respectively). There was no significant differences in the pregnancy rate (GIFT 69%, IUI 50.9%, respectively) or the delivery rate (GIFT 38.1%, IUI 25.5%) per patient. In group 2, there was no significant difference in the pregnancy rate (GIFT 54.5%, IUI 31.3%) or the delivery rate (GIFT 40.9%, IUI 12.5%) per cycle, but the difference in the pregnancy rate (GIFT 75%, IUI 35.7%) and the delivery rate (GIFT 56.3%, IUI 14.3%) per patient was significantly higher in GIFT compared to IUI (p = 0.04 and p = 0.02, respectively). We conclude that, when the same stimulation protocol is used in the early stages of endometriosis, a few cycles of IUI can achieve similar results to GIFT, and

  2. Modeling forage legume polycross pollen-parent gamete contributions to progeny based on empirical measurements with implications for effective polycross size

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Random mating is a fundamental assumption in quantitative genetic theory and assumes pollen-parents contribute uniform gamete numbers to the progeny generation; polycross-size-expected-inbreeding rests on this assumption. This study empirically determined polycross pollen-parent gamete frequency con...

  3. Gamete donors' expectations and experiences of contact with their donor offspring

    PubMed Central

    Kirkman, Maggie; Bourne, Kate; Fisher, Jane; Johnson, Louise; Hammarberg, Karin

    2014-01-01

    STUDY QUESTION What are the expectations and experiences of anonymous gamete donors about contact with their donor offspring? SUMMARY ANSWER Rather than consistently wanting to remain distant from their donor offspring, donors' expectations and experiences of contact with donor offspring ranged from none to a close personal relationship. WHAT IS KNOWN ALREADY Donor conception is part of assisted reproduction in many countries, but little is known about its continuing influence on gamete donors' lives. STUDY DESIGN, SIZE, DURATION A qualitative research model appropriate for understanding participants' views was employed; semi-structured interviews were conducted during January–March 2013. PARTICIPANTS/MATERIALS, SETTING, METHODS Before 1998, gamete donors in Victoria, Australia, were subject to evolving legislation that allowed them to remain anonymous or (from 1988) to consent to the release of identifying information. An opportunity to increase knowledge of donors' expectations and experiences of contact with their donor offspring recently arose in Victoria when a recommendation was made to introduce mandatory identification of donors on request from their donor offspring, with retrospective effect. Pre-1998 donors were invited through an advertising campaign to be interviewed about their views, experiences and expectations; 36 sperm donors and 6 egg donors participated. MAIN RESULTS AND THE ROLE OF CHANCE This research is unusual in achieving participation by donors who would not normally identify themselves to researchers or government inquiries. Qualitative thematic analysis revealed that most donors did not characterize themselves as parents of their donor offspring. Donors' expectations and experiences of contact with donor offspring ranged from none to a close personal relationship. LIMITATIONS, REASONS FOR CAUTION It is not possible to establish whether participants were representative of all pre-1998 donors. WIDER IMPLICATIONS OF THE FINDINGS Anonymous

  4. Salmonid Gamete Preservation in the Snake River Basin, 2001 Annual Report.

    SciTech Connect

    Armstrong, Robyn; Kucera, Paul

    2002-06-01

    Steelhead (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytscha) populations in the Northwest are decreasing. Genetic diversity is being lost at an alarming rate. Along with reduced population and genetic variability, the loss of biodiversity means a diminished environmental adaptability. The Nez Perce Tribe (Tribe) strives to ensure availability of genetic samples of the existing male salmonid population by establishing and maintaining a germplasm repository. The sampling strategy, initiated in 1992, has been to collect and preserve male salmon and steelhead genetic diversity across the geographic landscape by sampling within the major river subbasins in the Snake River basin, assuming a metapopulation structure existed historically. Gamete cryopreservation conserves genetic diversity in a germplasm repository, but is not a recovery action for listed fish species. The Tribe was funded in 2001 by the Bonneville Power Administration (BPA) and the U.S. Fish and Wildlife Service Lower Snake River Compensation Plan (LSRCP) to coordinate gene banking of male gametes from Endangered Species Act (ESA) listed steelhead and spring and summer chinook salmon in the Snake River basin. In 2001, a total of 398 viable chinook salmon semen samples from the Lostine River, Catherine Creek, upper Grande Ronde River, Lookingglass Hatchery (Imnaha River stock), Lake Creek, the South Fork Salmon River weir, Johnson Creek, Big Creek, Capehorn Creek, Marsh Creek, Pahsimeroi Hatchery, and Sawtooth Hatchery (upper Salmon River stock) were cryopreserved. Also, 295 samples of male steelhead gametes from Dworshak Hatchery, Fish Creek, Grande Ronde River, Little Sheep Creek, Pahsimeroi Hatchery and Oxbow Hatchery were also cryopreserved. The Grande Ronde chinook salmon captive broodstock program stores 680 cryopreserved samples at the University of Idaho as a long-term archive, half of the total samples. A total of 3,206 cryopreserved samples from Snake River basin steelhead and

  5. Comparative Mapping of the Oregon Wolfe Barley Using Doubled Haploid Lines Derived from Female and Male Gametes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Oregon Wolfe Barley mapping population is a resource for genetics research and instruction. Prior reports are based on a population of doubled haploid (DH) lines developed by the Hordeum bulbosum (H.b.) method, which samples female gametes. We developed new DH lines from the same cross using ant...

  6. 9 CFR 93.902 - Ports designated for the importation of live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of live fish, fertilized eggs, and gametes. 93.902 Section 93.902 Animals and Animal Products ANIMAL... (INCLUDING POULTRY) AND ANIMAL PRODUCTS IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN... Animal Species General Provisions for Svc-Regulated Fish Species § 93.902 Ports designated for...

  7. 9 CFR 93.902 - Ports designated for the importation of live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... of live fish, fertilized eggs, and gametes. 93.902 Section 93.902 Animals and Animal Products ANIMAL... (INCLUDING POULTRY) AND ANIMAL PRODUCTS IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN... Animal Species General Provisions for Svc-Regulated Fish Species § 93.902 Ports designated for...

  8. 9 CFR 93.902 - Ports designated for the importation of live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... of live fish, fertilized eggs, and gametes. 93.902 Section 93.902 Animals and Animal Products ANIMAL... (INCLUDING POULTRY) AND ANIMAL PRODUCTS IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN... Animal Species General Provisions for Svc-Regulated Fish Species § 93.902 Ports designated for...

  9. 9 CFR 93.902 - Ports designated for the importation of live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... of live fish, fertilized eggs, and gametes. 93.902 Section 93.902 Animals and Animal Products ANIMAL... (INCLUDING POULTRY) AND ANIMAL PRODUCTS IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN... Animal Species General Provisions for Svc-Regulated Fish Species § 93.902 Ports designated for...

  10. 9 CFR 93.902 - Ports designated for the importation of live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... of live fish, fertilized eggs, and gametes. 93.902 Section 93.902 Animals and Animal Products ANIMAL... (INCLUDING POULTRY) AND ANIMAL PRODUCTS IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN... Animal Species General Provisions for Svc-Regulated Fish Species § 93.902 Ports designated for...

  11. Reproductive and therapeutic cloning, germline therapy, and purchase of gametes and embryos: comments on Canadian legislation governing reproduction technologies

    PubMed Central

    Bernier, L; Gregoire, D

    2004-01-01

    In this article the three main topics covered in the new legislation are commented on: cloning, germline therapy, and purchase of gametes and embryos. Some important issues also covered in the new legislation, such as privacy and access to information, data protection, identity of donors, and inspection, will not be addressed. PMID:15574437

  12. Cryopreservation of Adult Male Spring and Summer Chinook Salmon Gametes in the Snake River Basin, 1997 Annual Report.

    SciTech Connect

    Faurot, Dave; Kucera, Paul A.; Armstrong, Robyn D.

    1998-06-01

    Chinook salmon populations in the Northwest are decreasing in number. The Nez Perce Tribe was funded in 1997 by the Bonneville Power Administration to coordinate and initiate gene banking of adult male gametes from Endangered Species Act (ESA) listed spring and summer chinook salmon in the Snake River basin.

  13. The Levels of Male Gametic Mitochondrial DNA Are Highly Regulated in Angiosperms with Regard to Mitochondrial Inheritance[W

    PubMed Central

    Wang, Dan-Yang; Zhang, Quan; Liu, Yang; Lin, Zhi-Fu; Zhang, Shao-Xiang; Sun, Meng-Xiang; Sodmergen

    2010-01-01

    The mechanisms that regulate mitochondrial inheritance are not yet clear, even though it is 100 years since the first description of non-Mendelian genetics. Here, we quantified the copy numbers of mitochondrial DNA (mtDNA) in the gametic cells of angiosperm species. We demonstrate that each egg cell from Arabidopsis thaliana, Antirrhinum majus, and Nicotiana tabacum possesses 59.0, 42.7, and 73.0 copies of mtDNA on average, respectively. These values are equivalent to those in Arabidopsis mesophyll cells, at 61.7 copies per cell. On the other hand, sperm or generative cells from Arabidopsis, A. majus, and N. tabacum possess minor amounts of mtDNA, at 0.083, 0.47, and 1 copy on average, respectively. We further reveal a 50-fold degradation of mtDNA during pollen development in A. majus. In contrast, markedly high levels of mtDNA are found in the male gametic cells of Cucumis melo and Pelargonium zonale (1296.3 and 256.7 copies, respectively). Our results provide direct evidence for mitochondrial genomic insufficiency in the eggs and somatic cells and indicate that a male gamete of an angiosperm may possess mtDNA at concentrations as high as 21-fold (C. melo) or as low as 0.1% (Arabidopsis) of the levels in somatic cells. These observations reveal the existence of a strong regulatory system for the male gametic mtDNA levels in angiosperms with regard to mitochondrial inheritance. PMID:20605854

  14. Rate constant and thermochemistry for K + O2 + N2 = KO2 + N2.

    PubMed

    Sorvajärvi, Tapio; Viljanen, Jan; Toivonen, Juha; Marshall, Paul; Glarborg, Peter

    2015-04-01

    The addition reaction of potassium atoms with oxygen has been studied using the collinear photofragmentation and atomic absorption spectroscopy (CPFAAS) method. KCl vapor was photolyzed with 266 nm pulses and the absorbance by K atoms at 766.5 nm was measured at various delay times with a narrow line width diode laser. Experiments were carried out with O2/N2 mixtures at a total pressure of 1 bar, over 748-1323 K. At the lower temperatures single exponential decays of [K] yielded the third-order rate constant for addition, kR1, whereas at higher temperatures equilibration was observed in the form of double exponential decays of [K], which yielded both kR1 and the equilibrium constant for KO2 formation. kR1 can be summarized as 1.07 × 10(-30)(T/1000 K)(-0.733) cm(6) molecule(-2) s(-1). Combination with literature values leads to a recommended kR1 of 5.5 × 10(-26)T(-1.55) exp(-10/T) cm(6) molecule(-2) s(-1) over 250-1320 K, with an error limit of a factor of 1.5. A van't Hoff analysis constrained to fit the computed ΔS298 yields a K-O2 bond dissociation enthalpy of 184.2 ± 4.0 kJ mol(-1) at 298 K and ΔfH298(KO2) = -95.2 ± 4.1 kJ mol(-1). The corresponding D0 is 181.5 ± 4.0 kJ mol(-1). This value compares well with a CCSD(T) extrapolation to the complete basis set limit, with all electrons correlated, of 177.9 kJ mol(-1). PMID:25775408

  15. Children Conceived by Gamete Donation: Psychological Adjustment and Mother-child Relationships at Age 7

    PubMed Central

    Golombok, Susan; Readings, Jennifer; Blake, Lucy; Casey, Polly; Mellish, Laura; Marks, Alex; Jadva, Vasanti

    2011-01-01

    An increasing number of babies are being born using donated sperm, where the child lacks a genetic link to the father, or donated eggs, where the child lacks a genetic link to the mother. This study examined the impact of telling children about their donor conception on mother-child relationships and children’s psychological adjustment. Assessments of maternal positivity, maternal negativity, mother-child interaction and child adjustment were administered to 32 egg donation, 36 donor insemination and 54 natural conception families with a 7-year-old child. Although no differences were found for maternal negativity or child adjustment, mothers in non-disclosing gamete donation families showed less positive interaction than mothers in natural conception families suggesting families may benefit from openness about the child’s genetic origins. PMID:21401244

  16. Collection of gametes from live axolotl, Ambystoma mexicanum, and standardization of in vitro fertilization.

    PubMed

    Mansour, N; Lahnsteiner, F; Patzner, R A

    2011-01-15

    This study established the first protocol for collection of gametes from live axolotl, Ambystoma mexicanum, by gentle abdominal massage and in vitro fertilization. To stimulate spermiation and ovulation, human chorionic gonadotrophin (hCG) and Ovopel pellets, which are commercially used to stimulate spawning in fish, were tested. The hCG was more effective than Ovopel pellets and yielded a higher semen volume in the injected males and a shorter response time in the females. Collected semen by this method was already motile and fertile. Fertile eggs could be collected in 3-4 successive collection times after the female has started the typical spawning behaviour. The fertilization condition that yielded the highest hatching rate was mixing semen with eggs before the addition of a fertilization saline solution (20 mmol/l NaCl, 1 mmol/l KCl, 1 mmol/l Mg(2)SO(4), 1 mmol Ca(2)Cl, 3 mmol NaHCO(3), 10 mmol/l Tris, pH 8.5 - Osmolality = 65 mosmol/kg). When the pH of the fertilization solution was increased to ≥ 10, the hatching rate was significantly increased. The use of fertilization solutions with osmolalities of ≥ 150 and ≥ 182 were accompanied with a significant decrease in hatching rates and the appearance of deformed larvae, respectively. In conclusion, a reliable protocol for gamete collection from live axolotl is established as a laboratory model of in vitro fertilization for urodele amphibians. This protocol may be transferable to endangered urodeles.

  17. Influence of sperm dilution and gamete contact time on the fertilization rate of scleractinian corals

    NASA Astrophysics Data System (ADS)

    Nozawa, Yoko; Isomura, Naoko; Fukami, Hironobu

    2015-12-01

    This study presents new information on the influence of sperm dilution on the fertilization rates of eight broadcast-spawning scleractinian coral species [three Acropora species and five merulinid species (three genera)]. The presented information nearly doubled the existing information, now totaling 17 species comprising eight acroporid species and nine merulinid species. No obvious differences in the fertilization rates were observed at the family and genus levels; furthermore, the fertilization curve estimated uniquely for Favites pentagona exhibited a strong sigmoid shape, indicating the existence of species-specific variation. In addition, a general fertilization response against sperm dilution was observed for the first time in broadcast-spawning scleractinian corals. The fertilization rate peaked (>75 %) at a sperm concentration of approximately 106 sperm mL-1 (optimal concentration) and rapidly declined to <50 % at a concentration of 104 sperm mL-1. The influence of gamete contact time (10, 30, and 60 min) on fertilization rates was also examined in two Acropora and four merulinid species, at the optimal sperm concentration. No influence of gamete contact time on fertilization rates was observed in two of the examined species ( Acropora papillare and Platygyra ryukyuensis), whereas reduced fertilization rates occurred mostly in the 10-min treatment for the other species. These results suggested that broadcast-spawning scleractinian corals can rapidly fertilize, indicating that these corals have a fair chance of achieving high fertilization success in the field under optimal conditions. The sperm concentration values (e.g., 104 sperm mL-1, indicating <50 % fertilization rates) may be useful in estimating the success of in situ fertilization of broadcast-spawning scleractinian corals, particularly in degraded, low-density populations where the degree of fertilization success is of management concern. Information on the fertilization ecology of scleractinian

  18. Effects of an oil production effluent on gametogenesis and gamete performance in the purple sea urchin (Strongylocentrotus purpuratus Stimpson)

    SciTech Connect

    Krause, P.R. . Dept. of Biological Sciences)

    1994-07-01

    Adult organisms subjected to chronic discharges from a point source of pollution may exhibit several sublethal responses. One such response is the impairment of gamete production. This may be expressed in the amount and/or quality of gametes produced by adults. In this study the effects of chronic exposure to produced water (an oil production effluent) on the gametogenesis and gamete performance of the purple sea urchin (Strongylocentrotus purpuratus Stimpson) were examined using an in situ caging experiment. Adult purple sea urchins were kept in benthic cages arrayed down-field from a discharging diffuser at 13 sites, with distances ranging from 5 to 1,000 m. Cage exposures were maintained in the field for eight weeks, and each cage held 25 animals. Gametogenesis was examined for each sex by comparing a size-independent measure of relative gonads ass as determined by analysis of covariance. Results showed that there was a significant negative relationship between these estimates of relative gonad mass and distance from the outfall for both sexes, indicating that sea urchins living closer to the outfall produced significantly larger gonads. Gamete performance was measured through a fertilization kinetics bioassay that held the concentration of eggs constant and varied the amount of sperm added. The proportion of eggs fertilized under each sperm concentration was determined and the response fit to a model of fertilizability showed a positive relationship with distance away from the outfall. These findings indicate that although adult sea urchins exposed to a produced water outfall exhibit larger gonads, they suffer a marked decrease in a gamete performance.

  19. Salmonid Gamete Preservation in the Snake River Basin : 2000 Annual Report.

    SciTech Connect

    Armstrong, Robyn; Kucera, Paul A.

    2001-06-01

    Steelhead (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytscha) populations in the Northwest are decreasing. Genetic diversity is being lost at an alarming rate. The Nez Perce Tribe (Tribe) strives to ensure availability of genetic samples of the existing male salmonid population by establishing and maintaining a germplasm repository. The sampling strategy, initiated in 1992, has been to collect and preserve male salmon and steelhead genetic diversity across the geographic landscape by sampling within the major river subbasins in the Snake River basin, assuming a metapopulation structure existed historically. Gamete cryopreservation conserves genetic diversity in a germplasm repository, but is not a recovery action for listed fish species. The Tribe was funded in 2000 by the Bonneville Power Administration (BPA) and the U.S. Fish and Wildlife Service Lower Snake River Compensation Plan (LSRCP) to coordinate gene banking of male gametes from Endangered Species Act listed steelhead and spring and summer chinook salmon in the Snake River basin. In 2000, a total of 349 viable chinook salmon semen samples from the Lostine River, Catherine Creek, upper Grande Ronde River, Lookingglass Hatchery (Imnaha River stock), Rapid River Hatchery, Lake Creek, the South Fork Salmon River weir, Johnson Creek, Big Creek, Capehorn Creek, Marsh Creek, Pahsimeroi Hatchery, and Sawtooth Hatchery (upper Salmon River stock) were cryopreserved. Also, 283 samples of male steelhead gametes from Dworshak Hatchery, Fish Creek, Grande Ronde River, Imnaha River, Little Sheep Creek, Pahsimeroi Hatchery and Oxbow Hatchery were also cryopreserved. The Tribe acquired 5 frozen steelhead samples from the Selway River collected in 1994 and 15 from Fish Creek sampled in 1993 from the U.S. Geological Survey, for addition into the germplasm repository. Also, 590 cryopreserved samples from the Grande Ronde chinook salmon captive broodstock program are being stored at the University of Idaho as

  20. ECO2N V2.0

    SciTech Connect

    Pan, Lehua; Spycher, Nicolas; Doughty, Christine; Pruess, Karsten

    2015-02-01

    ECO2N V2.0 is a fluid property module for the TOUGH2 simulator (Version 2.1) that was designed for applications to geologic sequestration of CO2 in saline aquifers and enhanced geothermal reservoirs. ECO2N V2.0 is an enhanced version of the previous ECO2N V1.0 module (Pruess, 2005). It expands the temperature range up to about 300oC whereas V1.0 can only be used for temperatures below about 110oC. V2.0 includes a comprehensive description of the thermodynamic and thermophysical properties of H2O - NaCl - CO2 mixtures, that reproduces fluid properties largely within experimental error for the temperature, pressure and salinity conditions 10 °C < T < 300 °C, P < 600 bar, and salinity up to halite saturation. This includes density, viscosity, and specific enthalpy of fluid phases as functions of temperature, pressure, and composition, as well as partitioning of mass components H2O, NaCl and CO2 among the different phases. In particular, V2.0 accounts for the effects of water on the thermophysical properties of the CO2-rich phase, which was ignored in V1.0, using a model consistent with the solubility models developed by Spycher and Pruess (2005, 2010). In terms of solubility models, V2.0 uses the same model for partitioning of mass components among the different phases (Spycher and Pruess, 2005) as V1.0 for the low temperature range (<99oC) but uses a new model (Spycher and Pruess, 2010) for the high temperature range (>109oC). In the transition range (99-109oC), a smooth interpolation is applied to estimate the partitioning as a function of the temperature. Flow processes can be modeled isothermally or non-isothermally, and phase conditions represented may include a single (aqueous or CO2-rich) phase, as well as two-phase (brine-CO2) mixtures. Fluid phases may appear or disappear in the course of a simulation, and solid salt may precipitate or dissolve. Note that the model cannot be applied to subcritical conditions that involves both liquid and gaseous CO2 unless

  1. ECO2N V2.0

    2015-02-01

    ECO2N V2.0 is a fluid property module for the TOUGH2 simulator (Version 2.1) that was designed for applications to geologic sequestration of CO2 in saline aquifers and enhanced geothermal reservoirs. ECO2N V2.0 is an enhanced version of the previous ECO2N V1.0 module (Pruess, 2005). It expands the temperature range up to about 300oC whereas V1.0 can only be used for temperatures below about 110oC. V2.0 includes a comprehensive description of the thermodynamic and thermophysical propertiesmore » of H2O - NaCl - CO2 mixtures, that reproduces fluid properties largely within experimental error for the temperature, pressure and salinity conditions 10 °C < T < 300 °C, P < 600 bar, and salinity up to halite saturation. This includes density, viscosity, and specific enthalpy of fluid phases as functions of temperature, pressure, and composition, as well as partitioning of mass components H2O, NaCl and CO2 among the different phases. In particular, V2.0 accounts for the effects of water on the thermophysical properties of the CO2-rich phase, which was ignored in V1.0, using a model consistent with the solubility models developed by Spycher and Pruess (2005, 2010). In terms of solubility models, V2.0 uses the same model for partitioning of mass components among the different phases (Spycher and Pruess, 2005) as V1.0 for the low temperature range (<99oC) but uses a new model (Spycher and Pruess, 2010) for the high temperature range (>109oC). In the transition range (99-109oC), a smooth interpolation is applied to estimate the partitioning as a function of the temperature. Flow processes can be modeled isothermally or non-isothermally, and phase conditions represented may include a single (aqueous or CO2-rich) phase, as well as two-phase (brine-CO2) mixtures. Fluid phases may appear or disappear in the course of a simulation, and solid salt may precipitate or dissolve. Note that the model cannot be applied to subcritical conditions that involves both liquid and gaseous CO2

  2. Effect of reproductive seasonality on gamete quality in the North American bison (Bison bison bison).

    PubMed

    Krishnakumar, S; Whiteside, D P; Elkin, B; Thundathil, J C

    2015-04-01

    The objective was to investigate the effects of reproductive seasonality on gamete quality in plains bison (Bison bison bison). Epididymal sperm (n = 61 per season), collected during the breeding season (July-September), had significantly higher post-thaw total motility (36.76 ± 14.18 vs 31.24 ± 12.74%), and lower linearity (0.36 ± 0.06 vs 0.39 ± 0.04) and wobbliness (0.49 ± 0.04 vs 0.51 ± 0.03; mean ± SD) compared to non-breeding season (January-March) samples. Representative samples (n = 4) from each season were used in heterologous IVF trials using cattle oocytes. Cleavage, morulae and blastocyst percentage were higher for breeding vs non-breeding season sperm samples (81.88 ± 6.8 vs 49.94 ± 6.77; 41.89 ± 13.40 vs 27.08 ± 23.21; and 30.49 ± 17.87 vs 13.72 ± 18.98%, respectively). Plains bison ovaries collected during the breeding (n = 97 pairs) and non-breeding (n = 100 pairs) seasons were classified as luteal or follicular. Oocytes recovered from these ovaries were classified into five grades based on morphology. There was no significant difference in the number of luteal ovaries or grades of oocytes recovered. Oocytes were matured, fertilized (with frozen sperm from three bison bulls) and cultured in vitro. Cleavage percentage was higher for oocytes collected during breeding vs non-breeding season (83.72 ± 6.42 vs 73.98 ± 6.43), with no significant difference in subsequent development to blastocysts. In summary, epididymal sperm from non-breeding season had decreased total motility and resulted in reduced embryo production in vitro. Oocytes collected during non-breeding season had reduced ability to be matured, fertilized and/or undergo cleavage in vitro. Data suggested that season influenced gamete quality in plains bison.

  3. Gamete ripening and hormonal correlates in three strains of lake trout

    USGS Publications Warehouse

    Foster, N.R.; O'Connor, D.V.; Schreck, C.B.

    1993-01-01

    In our 2-year laboratory study of hatchery-reared adult lake trout Salvelinus namaycush of the Seneca Lake, Marquette (Lake Superior Lean), and Jenny Lake strains, we compared gamete ripening times and changes in plasma concentrations of seven hormones. If interstrain differences in these traits were found, such differences might help explain the apparent failure of stocked fish of these strains to develop large, naturally reproducing populations in the Great Lakes. The complex temporal changes in plasma hormone levels that occur during sexual maturation in lake trout have not been previously described. We detected little evidence of temporal isolation that would prevent interbreeding among the three strains. Strain had no effect on ovulation date (OD) in either year. Strain did not affect spermiation onset date (SOD) in year 1 but did in year 2, when the mean SOD of Jenny Lake males was earlier than that of Seneca Lake males but not different from that of Marquette males. Hormonal data were normalized around ODs for individual females and SODs for individual males. In females, estradiol-17β (E2) was highest 8 weeks before the OD; the highest testosterone (T) level occurred 6 weeks before the OD, and the next highest level occurred simultaneously with the highest level of 11-ketotestosterone (11-KT) 2 weeks before the OD. Plasma levels of 17∝-hydroxy-20β-dihydroprogesterone (DHP) peaked 1 week before the OD, then abruptly declined immediately after. Cortisol (F), triiodothyronine (T3), and thyroxine (T4) were highly variable, but F was the only hormone that showed no trend with week in either year. In males, plasma E2 levels were highest 3 weeks before the SOD, highest levels of T and of 11-KT occurred simultaneously 2 weeks after the SOD, and DHP peaked 5 weeks after the SOD and 3 weeks after the highest levels of T and 11-KT. As in females, plasma levels of F, T3, and T4 were highly variable, and F was the only hormone that showed no trend with week in

  4. Localized bleaching in Hawaii causes tissue loss and a reduction in the number of gametes in Porites compressa

    NASA Astrophysics Data System (ADS)

    Sudek, M.; Aeby, G. S.; Davy, S. K.

    2012-06-01

    Localized bleaching (a discrete white area on the coral) was observed in one of the main framework-building corals in Hawaii, Porites compressa. This study aimed to determine the degree of virulence of the lesion. We investigated the whole-colony effects by following disease progression through time and examining the effect of localized bleaching on coral fecundity. After two months, 35 of 42 (83.3%) individually tagged colonies affected by localized bleaching showed tissue loss and partial colony mortality. Histological slides of healthy P. compressa and samples from colonies showing signs of localized bleaching were compared showing that affected colonies had a significant reduction (almost 50%) in gamete development, egg numbers, and egg size in the affected tissue. The observed localized bleaching results in both partial colony mortality and a reduced number of gametes and was termed Porites Bleaching with Tissue Loss (PBTL).

  5. Influences of DMP on the Fertilization Process and Subsequent Embryogenesis of Abalone (Haliotis diversicolor supertexta) by Gametes Exposure

    PubMed Central

    Cai, Zhong-Hua

    2011-01-01

    Di-methyl phthalate (DMP), a typical endocrine disrupting chemical (EDC), is ubiquitously distributed in aquatic environments; yet studies regarding its impact on gametes and the resulting effects on embryogenesis in marine gastropods are relatively scarce. In this study, the influences of DMP on the gametes and subsequent developmental process of abalone (Haliotis diversicolor supertexta, a representative marine benthic gastropod) were assessed. Newborn abalone eggs and sperm were exposed separately to different DMP concentrations (1, 10 or 100 ppb) for 60 min. At the end-point of exposure, the DMP-treated eggs and sperm were collected for analysis of their ultra-structures, ATPase activities and total lipid levels, and the fertilized gametes (embryos) were collected to monitor related reproductive parameters (fertilization rate, abnormal development rate and hatching success rate). Treatment with DMP did not significantly alter the structure or total lipid content of eggs at any of the doses tested. Hatching failures and morphological abnormalities were only observed with the highest dose of DMP (100 ppb). However, DMP exposure did suppress sperm ATPase activities and affect the morphological character of their mitochondria. DMP-treated sperm exhibited dose-dependent decreases in fertilization efficiency, morphogenesis and hatchability. Relatively obvious toxicological effects were observed when both sperm and eggs were exposed to DMP. Furthermore, RT-PCR results indicate that treatment of gametes with DMP changed the expression patterns of physiologically-regulated genes (cyp3a, 17β-HSD-11 and 17β-HSD-12) in subsequent embryogenesis. Taken together, this study proofed that pre-fertilization exposure of abalone eggs, sperm or both to DMP adversely affects the fertilization process and subsequent embryogenesis. PMID:22028799

  6. [Information, transmission, secrecy: What kind of discourse for children born by gamete donation?].

    PubMed

    Canneaux, M; Kobilinsky, N; Wolf, J P; Golse, B; Beauquier-Maccotta, B

    2016-01-01

    The number of children born through gamete donation grows by the conceptions made abroad. All the couples engaging in this process do not benefit from of the same support around the issues raised by the information to the child and its terms. Through a literature review, the authors explore the data on information intentions from parents to child and to entourage, the influence of the issue of anonymity, the effective rate information, the influences of the age of the child, the terms information and links with family dynamics. The quantitative findings underscore the complexity of this task, since 10-90 % of couples report an intention to inform their child from conception through donation, while 5-30 % actually inform them after birth. Fifty-nine to 93 % of the relatives are nevertheless informed. The authors will highlight the psychopathological tracks that support the possibility of narration for parents: the internalization of their infertility, the representation of the gift, the development of rivalry towards donors, the secrecy and privacy. The objective of this article is to enable carers to accompany this reflection among future parents, a better listening of the issues raise by the couples allowing shoring their process. PMID:27318771

  7. Effects of protracted cadmium exposure on gametes of the purple sea urchin, Arbacia punctulata

    SciTech Connect

    Bowen, W.J. III; Engel, D.W.

    1996-03-01

    Gametes and larvae of sea urchins and more specifically Arbacia punctulata have been used extensively in embryological studies and toxicity bioassay testing. Most of the experiments and bioassays have used the fertilized eggs of different sea urchin species and measured abnormal growth, malformations, or changes in the rates of growth as a function of contaminant exposure. Guida demonstrated that cupric ion activities of <10{sup -10.5} M caused reductions in the rates of growth of Arbacia Punctulata larvae and caused incomplete or malformed pluteal skeletons. These effects occurred at cupric ion concentrations that were in the same ranges as some measured in the more contaminated estuaries in the northeastern U.S. Sunda and coworkers also used sea urchin embryonic development to test potential trace metal toxicity in water samples collected from those same estuaries, and demonstrated toxicity potentially attributable to dissolved trace metals in the water column. The purpose of these experiments was to determine if protracted sublethal exposure of sexually mature sea urchins to dissolved cadmium in sea water would affect the viability of eggs and sperm, and whether it would affect fertilization and embryonic development and ultimately the larvae. The results of the experiments support the hypothesis that spermatogenesis and oogenesis were affected by cadmium exposure.

  8. Strategies for locating the female gamete: the importance of measuring sperm trajectories in three spatial dimensions

    PubMed Central

    Guerrero, Adán; Carneiro, Jorge; Pimentel, Arturo; Wood, Christopher D.; Corkidi, Gabriel; Darszon, Alberto

    2011-01-01

    The spermatozoon must find its female gamete partner and deliver its genetic material to generate a new individual. This requires that the spermatozoon be motile and endowed with sophisticated swimming strategies to locate the oocyte. A common strategy is chemotaxis, in which spermatozoa detect and follow a gradient of chemical signals released by the egg and its associated structures. Decoding the female gamete’s positional information is a process that spermatozoa undergo in a three-dimensional (3D) space; however, due to their speed and small size, this process has been studied almost exclusively in spermatozoa restricted to swimming in two dimensions (2D). This review examines the relationship between the mechanics of sperm propulsion and the physiological function of these cells in 3D. It also considers whether it is possible to derive all the 3D sperm swimming characteristics by extrapolating from 2D measurements. It is concluded that full insight into flagellar beat dynamics, swimming paths and chemotaxis under physiological conditions will eventually require quantitative imaging of flagellar form, ion flux changes, cell trajectories and modelling of free-swimming spermatozoa in 3D. PMID:21642645

  9. Effects of prolactin on gametes and zygotes during in vitro fertilization in mice.

    PubMed

    Fukuda, A; Noda, Y; Mori, T; Mori, C; Hashimoto, H; Hoshino, K

    1988-02-01

    Hyperprolactinemia is one of the major causative factors of infertility. However, the effect of prolactin on gametes during in vitro fertilization has not been elucidated. In the present study, the effects of mouse prolactin on the motility of spermatozoa, in vitro fertilization, and in vitro development of the zygote were investigated in mice using media containing three different concentrations (10, 50, and 100 ng/ml) of mouse prolactin. The development of unfertilized and fertilized oocytes (zygotes) was not affected in vitro by prolactin regardless of the amount of prolactin added to culture media. However, the fertilizing capacity of the spermatozoa was suppressed when they were preincubated for 90 min in culture media containing prolactin at concentrations of 50 and 100 ng/ml. The motility of spermatozoa was not affected by prolactin regardless of the concentration of prolactin used for preincubation. The present study indicates that prolactin may have some effects on the capacitation process of spermatozoa in vitro. This result should be taken into consideration in in vitro fertilization and embryo transfer procedures in humans.

  10. Regulating Gamete Donation in the U.S.: Ethical, Legal and Social Implications

    PubMed Central

    Sabatello, Maya

    2015-01-01

    This article explores the practice of gamete donation in the U.S. having in mind the larger question of what do we as a society owe children born as a result (donor-conceived children). Do recipient-parents have a duty to tell their donor-conceived child about his/her genetic origins? Should the identity of the donor be disclosed or remain anonymous? Does the child have a right to know her conception story and to receive information, including identifying information, about the donor? Furthermore, if a donor-conceived child has a right to know, who has the duty to tell her/him about it? The Article underscores the ethical, legal and social dilemmas that arise, comparing and contrasting with international developments in this arena. It highlights the market-based and more specific medical justifications for regulating this field, explores the emerging so-called right of the child to know his/her genetic origins (“the right to know”), and considers the challenges such a right evokes to existing legal culture and principles of medical ethics in the U.S. as well as other broader societal implications of such a right. PMID:26388996

  11. Cumulative pregnancy and live birth rates after gamete intra-Fallopian transfer.

    PubMed

    Rombauts, L; Dear, M; Breheny, S; Healy, D L

    1997-06-01

    To evaluate the efficacy of gamete intra-Fallopian transfer (GIFT) the Kaplan-Meier life table method was used to analyse a patient cohort treated with GIFT between 1991 and 1994. In a tertiary referral centre for reproductive medicine, 1628 women with a median age of 33 years and various causes of infertility were included to calculate cumulative pregnancy and live birth rates. Age and cause of infertility were main factor variables and the study was based on a total of 2941 consecutive GIFT cycles, leading to a first clinical pregnancy, and 3052 cycles, leading to a first live birth. The cumulative pregnancy and live birth rates were 49.6 and 38.8% respectively, after three initiated cycles and 64.1 and 52.0% respectively, after five initiated cycles. The multiple pregnancy rate was 22.6%. The implantation rate of 13.1% after GIFT demonstrates that the developing embryo benefits from a period of exposure within the environment of the Fallopian tube. The present results indicate that approximately 50% of couples will have at least one live baby after five initiated GIFT cycles. Advancing age was a major negative prognostic factor for the cumulative live birth rate because of higher cancellation rates, lower implantation rates and higher pregnancy failure rates. PMID:9222027

  12. [Information, transmission, secrecy: What kind of discourse for children born by gamete donation?].

    PubMed

    Canneaux, M; Kobilinsky, N; Wolf, J P; Golse, B; Beauquier-Maccotta, B

    2016-01-01

    The number of children born through gamete donation grows by the conceptions made abroad. All the couples engaging in this process do not benefit from of the same support around the issues raised by the information to the child and its terms. Through a literature review, the authors explore the data on information intentions from parents to child and to entourage, the influence of the issue of anonymity, the effective rate information, the influences of the age of the child, the terms information and links with family dynamics. The quantitative findings underscore the complexity of this task, since 10-90 % of couples report an intention to inform their child from conception through donation, while 5-30 % actually inform them after birth. Fifty-nine to 93 % of the relatives are nevertheless informed. The authors will highlight the psychopathological tracks that support the possibility of narration for parents: the internalization of their infertility, the representation of the gift, the development of rivalry towards donors, the secrecy and privacy. The objective of this article is to enable carers to accompany this reflection among future parents, a better listening of the issues raise by the couples allowing shoring their process.

  13. Telomere-to-centromere ratio of bovine clones, embryos, gametes, fetal cells, and adult cells.

    PubMed

    Meerdo, Lora N; Reed, William A; White, Kenneth L

    2005-01-01

    In 1997, Dolly, the first animal cloned from an adult cell, was born. It was announced in 1999 that Dolly might be aging faster than normal because her telomeres were shorter than age-matched control sheep. Telomeres, a repeated DNA sequence located at the ends of linear chromosomes, allow for base pair loss during DNA replication. Telomere shortening acts as a "mitotic clock," leading to replicative senescence. By using whole cell lysate and slot-blot analysis, we determined the telomere-to-centromere ratio (T/C) for bovine gametes, embryos, fetal tissues (brain, heart, lung, kidney, uterus, ovary, and skin), adult donor cells, and cloned embryos. Our data indicates a consistency in T/C among the various fetal tissues. The T/C of sperm is significantly lower than in oocytes. The T/C decreases from the oocyte to the 2-8-cell stage embryo, increases dramatically at the morula stage, and decreases at the blastocyst stage. Our data shows no significant difference in T/C between cloned embryos and in vitro fertilized (IVF) embryos, but there is a significant difference between cloned embryos and adult donor cells. In conclusion, the enucleated bovine oocyte has the ability to reestablish the telomere length of adult somatic cell donor nuclei. PMID:15996118

  14. An essential role of the basal body protein SAS-6 in Plasmodium male gamete development and malaria transmission.

    PubMed

    Marques, Sara R; Ramakrishnan, Chandra; Carzaniga, Raffaella; Blagborough, Andrew M; Delves, Michael J; Talman, Arthur M; Sinden, Robert E

    2015-02-01

    Gametocytes are the sole Plasmodium parasite stages that infect mosquitoes; therefore development of functional gametes is required for malaria transmission. Flagellum assembly of the Plasmodium male gamete differs from that of most other eukaryotes in that it is intracytoplasmic but retains a key conserved feature: axonemes assemble from basal bodies. The centriole/basal body protein SAS-6 normally regulates assembly and duplication of these organelles and its depletion causes severe flagellar/ciliary abnormalities in a diverse array of eukaryotes. Since basal body and flagellum assembly are intimately coupled to male gamete development in Plasmodium, we hypothesized that SAS-6 disruption may cause gametogenesis defects and perturb transmission. We show that Plasmodium berghei sas6 knockouts display severely abnormal male gametogenesis presenting reduced basal body numbers, axonemal assembly defects and abnormal nuclear allocation. The defects in gametogenesis reduce fertilization and render Pbsas6 knockouts less infectious to mosquitoes. Additionally, we show that lack of Pbsas6 blocks transmission from mosquito to vertebrate host, revealing an additional yet undefined role in ookinete to sporulating oocysts transition. These findings underscore the vulnerability of the basal body/SAS-6 to malaria transmission blocking interventions.

  15. Sex ratio and gamete size across eastern North America in Dictyostelium discoideum, a social amoeba with three sexes.

    PubMed

    Douglas, T E; Strassmann, J E; Queller, D C

    2016-07-01

    Theory indicates that numbers of mating types should tend towards infinity or remain at two. The social amoeba, Dictyostelium discoideum, however, has three mating types. It is therefore a mystery how this species has broken the threshold of two mating types, but has not increased towards a much higher number. Frequency-dependent selection on rare types in combination with isogamy, a form of reproduction involving gametes similar in size, could explain the evolution of multiple mating types in this system. Other factors, such as drift, may be preventing the evolution of more than three. We first looked for evidence of isogamy by measuring gamete size associated with each type. We found no evidence of size dissimilarities between gametes. We then looked for evidence of balancing selection, by examining mating type distributions in natural populations and comparing genetic differentiation at the mating type locus to that at more neutral loci. We found that mating type frequency varied among the three populations we examined, with only one of the three showing an even sex ratio, which does not support balancing selection. However, we found more population structure at neutral loci than the mating type locus, suggesting that the three mating types are indeed maintained at intermediate frequencies by balancing selection. Overall, the data are consistent with balancing selection acting on D. discoideum mating types, but with a sufficiently weak rare sex advantage to allow for drift, a potential explanation for why these amoebae have only three mating types.

  16. Food-Nonfood Discrimination in Ancestral Vertebrates: Gamete Cannibalism and the Origin of the Adaptive Immune System.

    PubMed

    Corcos, D

    2015-11-01

    Adaptive immunity is a complex system that appeared twice in vertebrates (in gnathostomes and in jawless fish) although it is not required for invertebrate defence. The adaptive immune system is tightly associated with self-non-self discrimination, and it is now clear that this interplay is not limited to the prevention of autoreactivity. Micro-organisms are usually considered for their pathogenicity or symbiotic ability, but, for most small metazoans, they mainly constitute food. Vertebrates are characterized by feeding by predation on larger preys, when compared to their ancestors who were filter feeders and ate micro-organisms. Predation gives a strong selective advantage, not only due to the availability of new food resources but also by the ability to eliminate competitors for environmental resources (intraguild predation (IGP)). Unlike size-structured IGP, intraspecific predation of juveniles, zygotes or gametes can be detrimental for species fitness in some circumstances. The ability of individuals to recognize highly polymorphic molecules on the surface of gametes present in the plankton and so distinguish self versus non-self gametes might have constituted a strong selective advantage in intraspecific competition. Here, I propose the theory that the capacity to rearrange receptors has been selected in ancestral vertebrates as a consequence of this strong need for discriminating between hetero-cannibalism versus filial cannibalism. This evolutionary origin sheds light on presently unexplained features of the immune system, including the existence of regulatory T cells and of non-pathogenic natural autoimmunity. PMID:26286030

  17. Sex ratio and gamete size across eastern North America in Dictyostelium discoideum, a social amoeba with three sexes.

    PubMed

    Douglas, T E; Strassmann, J E; Queller, D C

    2016-07-01

    Theory indicates that numbers of mating types should tend towards infinity or remain at two. The social amoeba, Dictyostelium discoideum, however, has three mating types. It is therefore a mystery how this species has broken the threshold of two mating types, but has not increased towards a much higher number. Frequency-dependent selection on rare types in combination with isogamy, a form of reproduction involving gametes similar in size, could explain the evolution of multiple mating types in this system. Other factors, such as drift, may be preventing the evolution of more than three. We first looked for evidence of isogamy by measuring gamete size associated with each type. We found no evidence of size dissimilarities between gametes. We then looked for evidence of balancing selection, by examining mating type distributions in natural populations and comparing genetic differentiation at the mating type locus to that at more neutral loci. We found that mating type frequency varied among the three populations we examined, with only one of the three showing an even sex ratio, which does not support balancing selection. However, we found more population structure at neutral loci than the mating type locus, suggesting that the three mating types are indeed maintained at intermediate frequencies by balancing selection. Overall, the data are consistent with balancing selection acting on D. discoideum mating types, but with a sufficiently weak rare sex advantage to allow for drift, a potential explanation for why these amoebae have only three mating types. PMID:27018644

  18. A single domain of the ZP2 zona pellucida protein mediates gamete recognition in mice and humans

    PubMed Central

    Avella, Matteo A.; Baibakov, Boris

    2014-01-01

    The extracellular zona pellucida surrounds ovulated eggs and mediates gamete recognition that is essential for mammalian fertilization. Zonae matrices contain three (mouse) or four (human) glycoproteins (ZP1–4), but which protein binds sperm remains controversial. A defining characteristic of an essential zona ligand is sterility after genetic ablation. We have established transgenic mice expressing human ZP4 that form zonae pellucidae in the absence of mouse or human ZP2. Neither mouse nor human sperm bound to these ovulated eggs, and these female mice were sterile after in vivo insemination or natural mating. The same phenotype was observed with truncated ZP2 that lacks a restricted domain within ZP251–149. Chimeric human/mouse ZP2 isoforms expressed in transgenic mice and recombinant peptide bead assays confirmed that this region accounts for the taxon specificity observed in human–mouse gamete recognition. These observations in transgenic mice document that the ZP251–149 sperm-binding domain is necessary for human and mouse gamete recognition and penetration through the zona pellucida. PMID:24934154

  19. Conundrums with penumbras: the right to privacy encompasses non-gamete providers who create preembryos with the intent to become parents.

    PubMed

    Dillon, Lainie M C

    2003-05-01

    To date, five state high courts have resolved disputes over frozen preembryos. These disputes arose during divorce proceedings between couples who had previously used assisted reproduction and cryopreserved excess preembryos. In each case, one spouse wished to have the preembryos destroyed, while the other wanted to be able to use or donate them in the future. The parties in these cases invoked the constitutional right to privacy to argue for dispositional control over the preembryos; two of the five cases were resolved by relying on this right. The constitutional right to privacy protects intimate decisions involving procreation, marriage, and family life. However, when couples use donated sperm or ova to create preembryos, a unique circumstance arises: one spouse--the gamete provider--is genetically related to the preembryos and the other is not. If courts resolve frozen preembryo disputes that involve non-gamete providers based on the constitutional right to privacy, they should find that the constitutional right to privacy encompasses the interests of both gamete and non-gamete providers. Individuals who create preembryos with the intent to become a parent have made an intimate decision involving procreation, marriage, and family life that falls squarely within the the right to privacy. In such cases, the couple together made the decision to create a family through the use of assisted reproduction, and the preembryos would not exist but for that joint decision. Therefore, gamete and non-gamete providers should be afforded equal constitutional protection in disputes over frozen preembryos.

  20. Symmetry Properties of Single-Walled BC2N Nanotubes

    SciTech Connect

    Pan, Hui; Feng, Yuan Ping; Lin, Jainyi

    2009-06-01

    The symmetry properties of the single-walled BC2N nanotubes were investigated. All the BC2N nanotubes possess nonsymmorphic line groups. In contrast with the carbon and boron nitride nanotubes, armchair and zigzag BC2N nanotubes belong to different line groups, depending on the index n (even or odd) and the vector chosen. The number of Raman- active phonon modes is almost twice that of the infrared-active phonon modes for all kinds of BC2N nanotubes.

  1. Specific transgenerational imprinting effects of the endocrine disruptor methoxychlor on male gametes.

    PubMed

    Stouder, Christelle; Paoloni-Giacobino, Ariane

    2011-02-01

    Endocrine-disrupting chemicals (EDCs), among which methoxychlor (MXC), have been reported to affect the male reproductive system. This study evaluates the possible deleterious effects of MXC on imprinted genes. After administration of the chemical in adult male mice or in pregnant mice we analyzed by pyrosequencing possible methylation defects in two paternally imprinted (H19 and Meg3 (Gtl2)) and three maternally imprinted (Mest (Peg1), Snrpn, and Peg3) genes in the sperm and in the tail, liver, and skeletal muscle DNAs of the adult male mice and of the male offspring. MXC treatment of adult mice decreased the percentages of methylated CpGs of Meg3 and increased those of Mest, Snrpn, and Peg3 in the sperm DNA. MXC treatment of pregnant mice decreased the mean sperm concentrations by 30% and altered the methylation pattern of all the imprinted genes tested in the F1 offspring. In the latter case, MXC effects were transgenerational but disappeared gradually from F1 to F3. MXC did not affect imprinting in the somatic cells, suggesting that it exerts its damaging effects via the process of reprogramming that is unique to gamete development. A systematic analysis at the CpG level showed a heterogeneity in the CpG sensitivity to MXC. This observation suggests that not only DNA methylation but also other epigenetic modifications can explain the transgenerational effects of MXC. The reported effects of EDCs on human male spermatogenesis might be mediated by complex imprinting alterations analogous to those described in this study.

  2. Divergent evolution of vitamin B9 binding underlies Juno-mediated adhesion of mammalian gametes.

    PubMed

    Han, Ling; Nishimura, Kaoru; Sadat Al Hosseini, Hamed; Bianchi, Enrica; Wright, Gavin J; Jovine, Luca

    2016-02-01

    The interaction between egg and sperm is the first necessary step of fertilization in all sexually reproducing organisms. A decade-long search for a protein pair mediating this event in mammals culminated in the identification of the glycosylphosphatidylinositol (GPI)-anchored glycoprotein Juno as the egg plasma membrane receptor of sperm Izumo1 [1,2]. The Juno-Izumo1 interaction was shown to be essential for fertilization since mice lacking either gene exhibit sex-specific sterility, making these proteins promising non-hormonal contraceptive targets [1,3]. No structural information is available on how gamete membranes interact at fertilization, and it is unclear how Juno - which was previously named folate receptor (FR) 4, based on sequence similarity considerations - triggers membrane adhesion by binding Izumo1. Here, we report the crystal structure of Juno and find that the overall fold is similar to that of FRα and FRβ but with significant flexibility within the area that corresponds to the rigid ligand-binding site of these bona fide folate receptors. This explains both the inability of Juno to bind vitamin B9/folic acid [1], and why mutations within the flexible region can either abolish or change the species specificity of this interaction. Furthermore, structural similarity between Juno and the cholesterol-binding Niemann-Pick disease type C1 protein (NPC1) suggests how the modified binding surface of Juno may recognize the helical structure of the amino-terminal domain of Izumo1. As Juno appears to be a mammalian innovation, our study indicates that a key evolutionary event in mammalian reproduction originated from the neofunctionalization of the vitamin B9-binding pocket of an ancestral folate receptor molecule.

  3. Divergent evolution of vitamin B9 binding underlies Juno-mediated adhesion of mammalian gametes

    PubMed Central

    Han, Ling; Nishimura, Kaoru; Sadat Al Hosseini, Hamed; Bianchi, Enrica; Wright, Gavin J.; Jovine, Luca

    2016-01-01

    Summary The interaction between egg and sperm is the first necessary step of fertilization in all sexually reproducing organisms. A decade-long search for a protein pair mediating this event in mammals culminated in the identification of the glycosylphosphatidylinositol (GPI)-anchored glycoprotein Juno as the egg plasma membrane receptor of sperm Izumo1 1, 2. The Juno–Izumo1 interaction was shown to be essential for fertilization since mice lacking either gene exhibit sex-specific sterility, making these proteins promising non-hormonal contraceptive targets 1, 3. No structural information is available on how gamete membranes interact at fertilization, and it is unclear how Juno — which was previously named folate receptor (FR) 4, based on sequence similarity considerations — triggers membrane adhesion by binding Izumo1. Here, we report the crystal structure of Juno and find that the overall fold is similar to that of FRα and FRβ but with significant flexibility within the area that corresponds to the rigid ligand-binding site of these bona fide folate receptors. This explains both the inability of Juno to bind vitamin B9/folic acid [1], and why mutations within the flexible region can either abolish or change the species specificity of this interaction. Furthermore, structural similarity between Juno and the cholesterol-binding Niemann-Pick disease type C1 protein (NPC1) suggests how the modified binding surface of Juno may recognize the helical structure of the amino-terminal domain of Izumo1. As Juno appears to be a mammalian innovation, our study indicates that a key evolutionary event in mammalian reproduction originated from the neofunctionalization of the vitamin B9-binding pocket of an ancestral folate receptor molecule. PMID:26859261

  4. The end of donor anonymity: how genetic testing is likely to drive anonymous gamete donation out of business.

    PubMed

    Harper, Joyce C; Kennett, Debbie; Reisel, Dan

    2016-06-01

    Thousands of people worldwide have been conceived using donor gametes, but not all parents tell their children of their origin. Several countries now allow donor-conceived offspring to potentially know their genetic parent if they are informed of their donor-conceived status. At the same time, personal genetic testing is a rapidly expanding field. Over 3 million people have already used direct-to-consumer genetic testing to find information about their ancestry, and many are participating in international genetic genealogy databases that will match them with relatives. The increased prevalence of these technologies poses numerous challenges to the current practice of gamete donation. (i) Whether they are donating in a country that practices anonymous donation or not, donors should be informed that their anonymity is not guaranteed, as they may be traced if their DNA, or that of a relative, is added to a database. (ii) Donor-conceived adults who have not been informed of their status may find out that they are donor-conceived. (iii) Parents using donor conception need to be fully informed that their children's DNA will identify that they are not the biological parents and they should be encouraged to disclose the use of donor gametes to their children. Together, these concerns make urgent a wide-ranging societal conversation about how to best safeguard and promote the interests of donor-conceived offspring and protect the rights of donors. Specifically, there is a need to ensure that new genetic information is communicated in a way that promotes both the safety and the privacy rights of offspring and donors alike. All parties concerned must be aware that, in 2016, donor anonymity does not exist.

  5. Gamete donation, information sharing and the best interests of the child: an overview of the psychosocial evidence.

    PubMed

    Freeman, Tabitha

    2015-03-01

    This paper overviews key empirical findings from social science research regarding the impact of gamete donation on child wellbeing. In particular, the paper addresses current regulatory debates concerning information sharing and the best interests of the child by considering psychosocial aspects of telling--or not telling--children about their donor conception and the identity of their donor. The paper identifies three core sets of empirical, ethical and policy concerns underpinning these debates relating to (i) the psychosocial impact of gamete donation per se on child wellbeing, (ii) the psychosocial impact of parental disclosure decisions on child wellbeing, and (iii) the psychosocial implications of donor identification for donor-conceived offspring. The paper illustrates how these concerns are framed by ideas about the significance-or not-of 'genetic relatedness'; ideas which have come to the fore in contemporary discussions about the potential consequences of donor-conceived individuals gaining access to their donor's identity. By drawing together research findings that may be pertinent to the regulation of gamete donation and information sharing, a further aim of this paper is to explore the potential use and misuse of empirical 'evidence' in ethical and policy debates. Whilst this paper starts from the premise that psychosocial data has a vital role in grounding normative discussions, it seeks to contribute to this dialogue by highlighting both the value and limitations of social science research. In particular, the paper argues for a cautious approach to applying psychosocial evidence to ethical issues that is sensitive to the caveats and nuances of research findings and the changing cultural and regulatory context.

  6. Gamete donation, information sharing and the best interests of the child: an overview of the psychosocial evidence

    PubMed Central

    Freeman, Tabitha

    2016-01-01

    This paper overviews key empirical findings from social science research regarding the impact of gamete donation on child wellbeing. In particular, the paper addresses current regulatory debates concerning information sharing and the best interests of the child by considering psychosocial aspects of telling - or not telling - children about their donor conception and the identity of their donor. The paper identifies three core sets of empirical, ethical and policy concerns underpinning these debates relating to (i) the psychosocial impact of gamete donation per se on child wellbeing, (ii) the psychosocial impact of parental disclosure decisions on child wellbeing, and (iii) the psychosocial implications of donor identification for donor-conceived offspring. The paper illustrates how these concerns are framed by ideas about the significance – or not – of ‘genetic relatedness’; ideas which have come to the fore in contemporary discussions about the potential consequences of donor-conceived individuals gaining access to their donor’s identity. By drawing together research findings that may be pertinent to the regulation of gamete donation and information sharing, a further aim of this paper is to explore the potential use and misuse of empirical ‘evidence’ in ethical and policy debates. Whilst this paper starts from the premise that psychosocial data has a vital role in grounding normative discussions, it seeks to contribute to this dialogue by highlighting both the value and limitations of social science research. In particular, the paper argues for a cautious approach to applying psychosocial evidence to ethical issues that is sensitive to the caveats and nuances of research findings and the changing cultural and regulatory context. PMID:25743051

  7. The end of donor anonymity: how genetic testing is likely to drive anonymous gamete donation out of business.

    PubMed

    Harper, Joyce C; Kennett, Debbie; Reisel, Dan

    2016-06-01

    Thousands of people worldwide have been conceived using donor gametes, but not all parents tell their children of their origin. Several countries now allow donor-conceived offspring to potentially know their genetic parent if they are informed of their donor-conceived status. At the same time, personal genetic testing is a rapidly expanding field. Over 3 million people have already used direct-to-consumer genetic testing to find information about their ancestry, and many are participating in international genetic genealogy databases that will match them with relatives. The increased prevalence of these technologies poses numerous challenges to the current practice of gamete donation. (i) Whether they are donating in a country that practices anonymous donation or not, donors should be informed that their anonymity is not guaranteed, as they may be traced if their DNA, or that of a relative, is added to a database. (ii) Donor-conceived adults who have not been informed of their status may find out that they are donor-conceived. (iii) Parents using donor conception need to be fully informed that their children's DNA will identify that they are not the biological parents and they should be encouraged to disclose the use of donor gametes to their children. Together, these concerns make urgent a wide-ranging societal conversation about how to best safeguard and promote the interests of donor-conceived offspring and protect the rights of donors. Specifically, there is a need to ensure that new genetic information is communicated in a way that promotes both the safety and the privacy rights of offspring and donors alike. All parties concerned must be aware that, in 2016, donor anonymity does not exist. PMID:27073260

  8. Theoretical study of edge states in BC2N nanoribbons with zigzag edges

    PubMed Central

    2013-01-01

    In this paper, electronic properties of BC2N nanoribbons with zigzag edges are studied theoretically using a tight binding model and the first-principles calculations based on the density functional theories. The zigzag BC2N nanoribbons have the flat bands when the atoms are arranged as B-C-N-C along the zigzag lines. In this arrangement, the effect of charge transfer is averaged since B and N atoms are doped in same sublattice sites. This effect is important for not only the formation of flat bands but also for the validity of the tight binding model for such system. PMID:23902682

  9. The effect of filamentous turf algal removal on the development of gametes of the coral Orbicella annularis.

    PubMed

    Cetz-Navarro, Neidy P; Carpizo-Ituarte, Eugenio J; Espinoza-Avalos, Julio; Chee-Barragán, Guillermina

    2015-01-01

    Macroalgae and filamentous turf algae (FTA) are abundant on degraded coral reefs, and the reproductive responses of corals may indicate sub-lethal stress under these conditions. The percentage of gametogenic stages (PGS) and the maximum diameter of eggs (MDE; or egg size) of Orbicella annularis were used to evaluate the effect of long- (7-10 months) and short-term (2.5 months) FTA removal (treatments T1 and T2, respectively) at both the beginning (May) and the end (August) of gametogenesis. Ramets (individual lobes of a colony) surrounded by FTA (T3) or crustose coralline algae (CCA; T4) were used as controls. The removal of FTA enhanced the development of gametes (i.e., a larger and higher percentage of mature gametes (PMG)) of O. annularis for T1 vs. T3 ramets in May and T1 and T2 vs. T3 ramets in August. Similar values of PGS and MDE between gametes from T3 and T4 in both May and August were unexpected because a previous study had shown that the same ramets of T4 (with higher tissue thickness, chlorophyll a cm-2 and zooxanthellae density and lower mitotic index values) were less stressed than ramets of T3. Evaluating coral stress through reproduction can reveal more sensitive responses than other biological parameters; within reproductive metrics, PGS can be a better stress indicator than egg size. The presence of turf algae strongly impacted the development of gametes and egg size (e.g., PMG in ramets with FTA removal increased almost twofold in comparison with ramets surrounded by FTA in August), most likely exerting negative chronic effects in the long run due to the ubiquity and permanence of turf algae in the Caribbean. These algae can be considered a stressor that affects coral sexual reproduction. Although the effects of turf algae on O. annularis are apparently less severe than those of other stressors, the future of this species is uncertain because of the combined impacts of these effects, the decline of O. annularis populations and the almost complete

  10. Hormonal induction of gamete release, and in-vitro fertilisation, in the critically endangered Southern Corroboree Frog, Pseudophryne corroboree

    PubMed Central

    2010-01-01

    Background Conservation Breeding Programs (CBP's) are playing an important role in the protection of critically endangered anuran amphibians, but for many species recruitment is not successful enough to maintain captive populations, or provide individuals for release. In response, there has been an increasing focus on the use of Assisted Reproductive Technologies (ART), including the administration of reproductive hormones to induce gamete release followed by in vitro fertilisation. The objective of this study was to test the efficacy of two exogenous hormones to induce gamete release, for the purpose of conducting in vitro fertilisation (IVF), in one of Australia's most critically endangered frog species, Pseudophryne corroboree. Methods Male frogs were administered a single dose of either human chorionic gonadotropin (hCG) or luteinizing hormone-releasing hormone (LHRHa), while female frogs received both a priming and ovulatory dose of LHRHa. Spermiation responses were evaluated at 3, 7, 12, 24, 36, 48, 60 and 72 h post hormone administration (PA), and sperm number and viability were quantified using fluorescent microscopy. Ovulation responses were evaluated by stripping females every 12 h PA for 5 days. Once gametes were obtained, IVF was attempted by combining spermic urine with oocytes in a dilute solution of simplified amphibian ringer (SAR). Results Administration of both hCG and LHRHa induced approximately 80% of males to release sperm over 72 h. Peak sperm release occurred at 12 h PA for hCG treated males and 36 h PA for LHRHa treated males. On average, LHRHa treated males released a significantly higher total number of live sperm, and a higher concentration of sperm, over a longer period. In female frogs, administration of LHRHa induced approximately 30% of individuals to release eggs. On average, eggs were released between 24 and 48 h PA, with a peak in egg release at 36 h PA. IVF resulted in a moderate percentage (54.72%) of eggs being fertilised

  11. Making gametes from pluripotent stem cells--a promising role for very small embryonic-like stem cells.

    PubMed

    Bhartiya, Deepa; Hinduja, Indira; Patel, Hiren; Bhilawadikar, Rashmi

    2014-11-24

    The urge to have one's own biological child supersedes any desire in life. Several options have been used to obtain gametes including pluripotent stem cells (embryonic ES and induced pluripotent iPS stem cells); gonadal stem cells (spermatogonial SSCs, ovarian OSCs stem cells), bone marrow, mesenchymal cells and fetal skin. However, the field poses a huge challenge including inefficient existing protocols for differentiation, epigenetic and genetic changes associated with extensive in vitro manipulation and also ethical/regulatory constraints. A tremendous leap in the field occurred using mouse ES and iPS cells wherein they were first differentiated into epiblast-like cells and then primordial germ cell-like cells. These on further development produced sperm, oocytes and live offspring (had associated genetic problems). Evidently differentiating pluripotent stem cells into primordial germ cells (PGCs) remains a major bottleneck. Against this backdrop, we propose that a novel population of pluripotent stem cells termed very small embryonic-like stem cells (VSELs) may serve as an alternative, potential source of autologus gametes, keeping in mind that they are indeed PGCs surviving in adult mammalian ovaries and testes. Both VSELs and PGCs are pluripotent, relatively quiescent because of epigenetic modifications of parentally imprinted genes loci like Igf2-H19 and KCNQ1p57, share several markers like Stella, Fragilis, Mvh, Dppa2, Dppa4, Sall4, Blimp1 and functional receptors. VSELs are localized in the basement membrane of seminiferous tubules in testis and in the ovary surface epithelium. Ovarian stem cells from mouse, rabbit, sheep, marmoset and humans (menopausal women and those with premature ovarian failure) spontaneously differentiate into oocyte-like structures in vitro with no additional requirement of growth factors. Thus a more pragmatic option to obtain autologus gametes may be the pluripotent VSELs and if we could manipulate them in vivo - existing

  12. The Effect of Filamentous Turf Algal Removal on the Development of Gametes of the Coral Orbicella annularis

    PubMed Central

    Cetz-Navarro, Neidy P.; Carpizo-Ituarte, Eugenio J.; Espinoza-Avalos, Julio; Chee-Barragán, Guillermina

    2015-01-01

    Macroalgae and filamentous turf algae (FTA) are abundant on degraded coral reefs, and the reproductive responses of corals may indicate sub-lethal stress under these conditions. The percentage of gametogenic stages (PGS) and the maximum diameter of eggs (MDE; or egg size) of Orbicella annularis were used to evaluate the effect of long- (7–10 months) and short-term (2.5 months) FTA removal (treatments T1 and T2, respectively) at both the beginning (May) and the end (August) of gametogenesis. Ramets (individual lobes of a colony) surrounded by FTA (T3) or crustose coralline algae (CCA; T4) were used as controls. The removal of FTA enhanced the development of gametes (i.e., a larger and higher percentage of mature gametes (PMG)) of O. annularis for T1 vs. T3 ramets in May and T1 and T2 vs. T3 ramets in August. Similar values of PGS and MDE between gametes from T3 and T4 in both May and August were unexpected because a previous study had shown that the same ramets of T4 (with higher tissue thickness, chlorophyll a cm-2 and zooxanthellae density and lower mitotic index values) were less stressed than ramets of T3. Evaluating coral stress through reproduction can reveal more sensitive responses than other biological parameters; within reproductive metrics, PGS can be a better stress indicator than egg size. The presence of turf algae strongly impacted the development of gametes and egg size (e.g., PMG in ramets with FTA removal increased almost twofold in comparison with ramets surrounded by FTA in August), most likely exerting negative chronic effects in the long run due to the ubiquity and permanence of turf algae in the Caribbean. These algae can be considered a stressor that affects coral sexual reproduction. Although the effects of turf algae on O. annularis are apparently less severe than those of other stressors, the future of this species is uncertain because of the combined impacts of these effects, the decline of O. annularis populations and the almost

  13. Selling blood and gametes during tough economic times: insights from Google search

    PubMed Central

    Wu, Jonathan A.; Ngo, Tin C.; Rothman, Cathy; Breyer, Benjamin; Eisenberg, Michael L.

    2016-01-01

    Introduction To use Google Insights search volume and publicly available economic indicators to test the hypothesis that sperm, egg, and blood donations increase during economic downturns and to demonstrate the feasibility of using Google search volume data to predict national trends in actual sperm, egg, and blood donations rates. Materials and methods Cross-correlation statistical analysis comparing Google search data for terms relating to blood, egg, and sperm donations with various economic indicators including the S&P 500 closing values, gross domestic product (GDP), the U.S. Index of Leading Indicators (U.S. Leading Index), gross savings rate, mortgage interest rates, unemployment rate, and consumer price index (CPI) from 2004–2011. A secondary analysis determined the Pearson correlation coefficient between Google search data with actual sperm, egg, and blood donation volume in the U.S. as measured by California Cryobank, the National Assisted Reproductive Technology Surveillance System, and the National Blood Collection and Utilization Survey, respectively. Significance of cross-correlation and Pearson correlation analysis as indicated by p value. Results There were several highly significant cross-correlation relationships between search volume and various economic indicators. Correlation between Google search volume for the term “sperm donation,” “egg donation,” and “blood donation” with actual number of sperm, egg and blood donations in the United States demonstrated Pearson correlation coefficients of 0.2 (p > 0.10), −0.1 (p > 0.10), and 0.07 (p > 0.10), respectively. Temporal analysis showed an improved correlation coefficient of 0.9 (p < 0.05) for blood donation when shifted 12 months later relative to Google search volume. Conclusion Google search volume data for search terms relating to sperm, egg, and blood donation increase during economic downturns. This finding suggests gamete and bodily fluid donations are influenced by market

  14. Gas-phase kinetics of the N + C2N reaction at low temperature.

    PubMed

    Stubbing, James W; Vanuzzo, Gianmarco; Moudens, Audrey; Loison, Jean-Christophe; Hickson, Kevin M

    2015-04-01

    The rate of the gas-phase N((4)S) + C2N(X(2)Πi) reaction has been measured in a continuous supersonic flow reactor down to 54 K through the relative-rate method using the N((4)S) + OH(X(2)Π) → H((2)S) + NO(X(2)Π) reaction as a reference. The microwave discharge technique was employed to produce high concentrations of atomic nitrogen. Pulsed laser photolysis of precursor molecules Cl3C2N and H2O2 at 212 nm in situ led to C2N and OH radical formation, respectively. The rate constant is shown to be approximately independent of temperature, in contrast to previous studies of atom-radical reactions involving atomic nitrogen. While the reaction rate is faster than previously estimated, astrochemical simulations indicate that this reaction is probably only a minor source of CN radicals in dense interstellar clouds.

  15. Investigation of the Semicoa 2N7616 and 2N7425 and the Microsemi 2N7480 for Single-Event Gate Rupture and Single-Event Burnout

    NASA Technical Reports Server (NTRS)

    Scheick, Leif

    2014-01-01

    Single-event-effect test results for hi-rel total-dose-hardened power MOSFETs are presented in this report. The 2N7616 and the 2N7425 from Semicoa and the 2N7480 from International Rectifier were tested to NASA test condition standards and requirements. The 2N7480 performed well and the data agree with the manufacture's data. The 2N7616 and 2N7425 were entry parts from Semicoa using a new device architecture. Unfortunately, the device performed poorly and Semicoa is withdrawing power MOSFETs from it line due to these data. Vertical metal-oxide-semiconductor field-effect transistors (MOSFETs) are the most commonly used power transistor. MOSFETs are typically employed in power supplies and high current switching applications. Due to the inherent high electric fields in the device, power MOSFETs are sensitive to heavy ion irradiation and can fail catastrophically as a result of single-event gate rupture (SEGR) or single-event burnout (SEB). Manufacturers have designed radiation-hardened power MOSFETs for space applications. See [1] through [5] for more information. The objective of this effort was to investigate the SEGR and SEB responses of two power MOSFETs recently produced. These tests will serve as a limited verification of these parts. It is acknowledged that further testing on the respective parts may be needed for some mission profiles.

  16. Susceptibility of gametes and embryos of the eastern oyster, Crassostrea virginica, to Karenia brevis and its toxins.

    PubMed

    Rolton, Anne; Soudant, Philippe; Vignier, Julien; Pierce, Richard; Henry, Michael; Shumway, Sandra E; Bricelj, V Monica; Volety, Aswani K

    2015-06-01

    The bivalve mollusc, Crassostrea virginica, is frequently exposed to blooms of Karenia brevis along the west coast of Florida during periods of spawning and early larval development. A continuous 4-day exposure of gametes and 2-4 cell stage embryos of C. virginica to whole-cell and culture filtrate of K. brevis at 500 and 5000 cells mL(-1), was followed by a 4-day 'recovery' period. Larval growth, percent of normal, abnormal and dead larvae, and the presence of food in the larval gut were measured throughout the exposure period. Results suggest that negative effects mainly occur during embryogenesis and early development. Damage to feeding apparatus/gut may occur during embryonic development or exposure to toxins may act as a feeding deterrent on non-toxic algae. Following 2-h in vitro exposure of gametes, differences in oocyte and sperm cell parameters were investigated using flow cytometry. The reduced sperm viability in the whole-cell 5000 cells mL(-1) treatment suggests the involvement of extracellular brevetoxins (PbTx) and perhaps other harmful, uncharacterized compounds associated with the K. brevis cell membrane. The cumulative effects of reduced sperm viability, fertilization success, embryonic and larval survival, and the near-annual exposure to blooms of K. brevis could cause significant bottlenecks on oyster recruitment.

  17. Epithelial and neural cadherin expression in the mammalian reproductive tract and gametes and their participation in fertilization-related events.

    PubMed

    Vazquez-Levin, Mónica Hebe; Marín-Briggiler, Clara Isabel; Caballero, Julieta Natalia; Veiga, María Florencia

    2015-05-01

    Mammalian fertilization involves a series of well-orchestrated cell-cell interaction steps between gametes, as well as among spermatozoa and somatic cells of both the male and female reproductive tracts. Cadherins are Ca(2+)-dependent glycoproteins that have been involved in cellular adhesion and signaling in somatic cells. Taking into account that Ca(2+) ions are required during fertilization, the involvement of these proteins in adhesion events during this process can be anticipated. This report presents an overview on two members of classical cadherins, Epithelial (E-) and Neural (N-) cadherin in reproductive biology. Its provides evidence of studies done by several research groups about the expression of E- and N-cadherin during spermatogenesis, oogenesis and folliculogenesis, and their involvement in gamete transport in the reproductive tracts. Moreover, it describes current knowledge of E- and N-cadherin presence in cells of the cumulus-oocyte complex and spermatozoa from several mammalian species, and shows gathered evidence on their participation in different steps of the fertilization process. A brief summary on general information of both proteins is also presented.

  18. Susceptibility of gametes and embryos of the eastern oyster, Crassostrea virginica, to Karenia brevis and its toxins.

    PubMed

    Rolton, Anne; Soudant, Philippe; Vignier, Julien; Pierce, Richard; Henry, Michael; Shumway, Sandra E; Bricelj, V Monica; Volety, Aswani K

    2015-06-01

    The bivalve mollusc, Crassostrea virginica, is frequently exposed to blooms of Karenia brevis along the west coast of Florida during periods of spawning and early larval development. A continuous 4-day exposure of gametes and 2-4 cell stage embryos of C. virginica to whole-cell and culture filtrate of K. brevis at 500 and 5000 cells mL(-1), was followed by a 4-day 'recovery' period. Larval growth, percent of normal, abnormal and dead larvae, and the presence of food in the larval gut were measured throughout the exposure period. Results suggest that negative effects mainly occur during embryogenesis and early development. Damage to feeding apparatus/gut may occur during embryonic development or exposure to toxins may act as a feeding deterrent on non-toxic algae. Following 2-h in vitro exposure of gametes, differences in oocyte and sperm cell parameters were investigated using flow cytometry. The reduced sperm viability in the whole-cell 5000 cells mL(-1) treatment suggests the involvement of extracellular brevetoxins (PbTx) and perhaps other harmful, uncharacterized compounds associated with the K. brevis cell membrane. The cumulative effects of reduced sperm viability, fertilization success, embryonic and larval survival, and the near-annual exposure to blooms of K. brevis could cause significant bottlenecks on oyster recruitment. PMID:25771241

  19. Changes in spawning time led to the speciation of the broadcast spawning corals Acropora digitifera and the cryptic species Acropora sp. 1 with similar gamete recognition systems

    NASA Astrophysics Data System (ADS)

    Ohki, Shun; Kowalski, Radoslaw K.; Kitanobo, Seiya; Morita, Masaya

    2015-12-01

    Multi-species spawning is reported in the coral genus Acropora, but hybridization in nature rarely occurs because of the incompatibility of gametes and the timing of spawning. However, the evolutionary relationships between gamete compatibility and spawning time are obscure. Investigations of gamete compatibility in sister species that spawn at different times may provide clues to answering this question. Acropora sp. 1 has been defined as a cryptic species of Acropora digitifera, and they are morphologically similar, but spawn in different months, suggesting that they are either a cryptic species or a different species. We examined the morphology and conducted crossing experiments using cryopreserved sperm. The morphologies (branch length, branch width, and outer diameter of axial corallites) of A. digitifera and Acropora sp. 1 differed significantly. A phylogenetic tree of partial Pax- C nuclear sequences from A. digitifera and Acropora sp. 1 shows that they are monophyletic and closely related genetically, based on F ST values and P-distance. These results imply that these two species originated recently from a common ancestor. In addition, cryopreserved sperm from both A. digitifera and Acropora sp. 1 showed bidirectional inter-crossing (cryopreserved sperm of A. digitifera and eggs of Acropora sp. 1 from Sesoko: 32.1 ± 6.7 %, control-conspecific cryopreserved sperm and eggs: 46.1 ± 10.6 %; cryopreserved sperm of Acropora sp. 1 and eggs of A. digitifera from Oku: 63.3 ± 16.6 %, control: 83.6 ± 6.0 %). The results suggest that the gametes of these two species are compatible and that the pre-zygotic isolation mechanism is relaxed because their gametes do not interact. Overall, these two species should be classified as distinct species, and changes in spawning time are related to speciation in a similar gamete recognition system.

  20. Theoretical investigation on the chemistry of entrapment of the elusive aminoborane (H2 N=BH2 ) molecule.

    PubMed

    Malakar, Tanmay; Bhunya, Sourav; Paul, Ankan

    2015-04-20

    Aminoborane (H2 N=BH2 ) is an elusive entity and is thought to be produced during dehydropolymerization of ammonia borane, a molecule of prime interest in the field of chemical hydrogen storage. The entrapment of H2 N=BH2 through hydroboration of exogenous cyclohexene has emerged as a routine technique to infer if free H2 N=BH2 is produced or not during metal-catalyzed ammonia borane dehydrogenation reactions. But to date, the underlying mechanism of this trapping reaction remains unexplored. Herein, by using DFT calculations, we have investigated the mechanism of trapping of H2 N=BH2 by cyclohexene. Contrary to conventional wisdom, our study revealed that the trapping of H2 N=BH2 does not occur through direct hydroboration of H2 N=BH2 on the double bond of cyclohexene. We found that autocatalysis by H2 N=BH2 is crucial for the entrapment of another H2 N=BH2 molecule by cyclohexene. Additionally, nucleophilic assistance from the solvent is also implicated for the entrapment reaction carried out in nucleophilic solvents. In THF, the rate-determining barrier for formation of the trapping product was predicted to be 16.7 kcal mol(-1) at M06 L(CPCM) level of theory.

  1. Formation and structural organization of the egg-sperm bundle of the scleractinian coral Montipora capitata

    NASA Astrophysics Data System (ADS)

    Padilla-Gamiño, J. L.; Weatherby, T. M.; Waller, R. G.; Gates, R. D.

    2011-06-01

    The majority of scleractinian corals are hermaphrodites that broadcast spawn their gametes separately or packaged as egg-sperm bundles during spawning events that are timed to the lunar cycle. The egg-sperm bundle is an efficient way of transporting gametes to the ocean surface where fertilization takes place, while minimizing sperm dilution and maximizing the opportunity for gamete encounters during a spawning event. To date, there are few studies that focus on the formation and structure of egg-sperm bundle. This study explores formation, ultrastructure, and longevity of the egg-sperm bundle in Montipora capitata, a major reef building coral in Hawai`i. Our results show that the egg-sperm bundle is formed by a mucus layer secreted by the oocytes. The sperm package is located at the center of each bundle, possibly reflecting the development of male and female gametes in different mesenteries. Once the egg-sperm bundle has reached the ocean surface, it breaks open within 10-35 min, depending on the environmental conditions (i.e., wind, water turbulence). Although the bundle has an ephemeral life span, the formation of an egg-sperm bundle is a fundamental part of the reproductive process that could be strongly influenced by climate change and deterioration of water quality (due to anthropogenic effects) and thus requires further investigation.

  2. Pattern formation in miniature: the female gametophyte of flowering plants.

    PubMed

    Sundaresan, Venkatesan; Alandete-Saez, Monica

    2010-01-01

    Plant reproduction involves gamete production by a haploid generation, the gametophyte. For flowering plants, a defining characteristic in the evolution from the 'naked-seed' plants, or gymnosperms, is a reduced female gametophyte, comprising just seven cells of four different types--a microcosm of pattern formation and gamete specification about which only little is known. However, several genes involved in the differentiation, fertilization and post-fertilization functions of the female gametophyte have been identified and, recently, the morphogenic activity of the plant hormone auxin has been found to mediate patterning and egg cell specification. This article reviews recent progress in understanding the pattern formation, maternal effects and evolution of this essential unit of plant reproduction. PMID:20040485

  3. Formation of triploid plants via possible polyspermy.

    PubMed

    Toda, Erika; Okamoto, Takashi

    2016-09-01

    Polyploidization is a common phenomenon in angiosperms, and polyploidy has played a major role in the long-term diversification and evolutionary success of plants. Triploid plants are considered as the intermediate stage in the formation of stable autotetraploid plants, and this pathway of tetraploid formation is known as the triploid bridge. As for the mechanism of triploid formation among diploid populations, fusion of an unreduced gamete with a reduced gamete is generally accepted. In addition, the possibility of polyspermy has been proposed for maize, wheat and some orchids, although it has been regarded as an uncommon mechanism of polyploid formation. One of the reasons why polyspermy is regarded as uncommon is because it is difficult to reproduce the polyspermy situation in zygotes and to analyze the developmental profiles of polyspermic zygotes. In the study, we produced polyspermic rice zygotes by electric fusion of an egg cell with two sperm cells and monitored their developmental profiles. The two sperm nuclei and the egg nucleus fused into a zygotic nucleus in the polyspermic zygote, and the triploid zygote divided into a two-celled embryo via mitotic division with a typical bipolar microtubule spindle. The two-celled proembryos developed and regenerated into triploid plants. These results suggest that polyspermic plant zygotes have the potential to form triploid embryos, and that polyspermy in angiosperms might be a pathway for the formation of triploid plants. PMID:27617495

  4. Assessing risks of invasion through gamete performance: farm Atlantic salmon sperm and eggs show equivalence in function, fertility, compatibility and competitiveness to wild Atlantic salmon

    PubMed Central

    Yeates, Sarah E; Einum, Sigurd; Fleming, Ian A; Holt, William V; Gage, Matthew JG

    2014-01-01

    Adaptations at the gamete level (a) evolve quickly, (b) appear sensitive to inbreeding and outbreeding and (c) have important influences on potential to reproduce. We apply this understanding to problems posed by escaped farm salmon and measure their potential to reproduce in the wild. Farm Atlantic salmon (Salmo salar) are a threat to biodiversity, because they escape in large numbers and can introgress, dilute or disrupt locally adapted wild gene pools. Experiments at the whole fish level have found farm reproductive potential to be significant, but inferior compared to wild adults, especially for males. Here, we assess reproductive performance at the gamete level through detailed in vitro comparisons of the form, function, fertility, compatibility and competitiveness of farm versus wild Atlantic salmon sperm and eggs, in conditions mimicking the natural gametic microenvironment, using fish raised under similar environmental conditions. Despite selective domestication and reduced genetic diversity, we find functional equivalence in all farm fish gamete traits compared with their wild ancestral strain. Our results identify a clear threat of farm salmon reproduction with wild fish and therefore encourage further consideration of using triploid farm strains with optimized traits for aquaculture and fish welfare, as triploid fish remain reproductively sterile following escape. PMID:24822083

  5. Evidence for a Polymorphism in Gametic Segregation Using a Malate Dehydrogenase Locus in the Tetraploid Treefrog HYLA VERSICOLOR

    PubMed Central

    Danzmann, Roy G.; Bogart, James P.

    1982-01-01

    Artificial cross combinations of tetraploid Hyla versicolor were analyzed electrophoretically using a polymorphic malate dehydrogenase locus (MDH-1) to determine the mechanism of chromosome segregation. Models for differentiating between disomic and tetrasomic inheritance are presented and tested. In some crosses progeny genotypes fit a disomic mode of segregation. In other crosses there is only evidence for a tetrasomic mode of segregation. Additional crosses produced genotypic ratios which conformed to either a disomic or tetrasomic mode of segregation. The same type of inheritance was demonstrated for any individual when used in multiple cross combinations. These results suggest that there exists in H. versicolor a polymorphism with respect to segregation of gametes, resulting from differences in chromosome pairings during meiosis I. PMID:7106558

  6. Reproductive semi-cloning respecting biparental embryo origin: embryos from syngamy between a gamete and a haploidized somatic cell.

    PubMed

    Tesarik, J

    2002-08-01

    Embryos formed by somatic cell nuclear transfer to enucleated oocytes (cloning) have given rise to viable offspring in several mammalian species. The possibility of future application of this technique to human assisted reproduction (reproductive cloning) has been widely debated. On this background there is current discussion of the potential for a cloning-derived technique, which aims at syngamy between a gamete nucleus from one parent and a somatic cell nucleus from the other. Critical analysis of the clinical indications, the current state of the art, biological concerns and ethical considerations relative to this technique, called here reproductive semi-cloning, are presented. Such a technique requires validation by further research before it can be considered as a treatment option. This debate explores issues raised by the technique.

  7. Reproductive and therapeutic cloning, germline therapy, and purchase of gametes and embryos: comments on Canadian legislation governing reproduction technologies.

    PubMed

    Bernier, L; Grégoire, D

    2004-12-01

    In Canada, the Assisted Human Reproduction Act received royal assent on 29 March 2004. The approach proposed by the federal government responds to Canadians' strong desire for an enforceable legislative framework in the field of reproduction technologies through criminal law. As a result of the widening gap between the rapid pace of technological change and governing legislation, a distinct need was perceived to create a regulatory framework to guide decisions regarding reproductive technologies. In this article the three main topics covered in the new legislation are commented on: cloning, germline therapy, and purchase of gametes and embryos. Some important issues also covered in the new legislation, such as privacy and access to information, data protection, identity of donors, and inspection, will not be addressed.

  8. Dynamics of an enzyme polymorphism in the isopod, Sphaeroma rugicauda (Leach). II. Sexual, gametic and fecundity selection.

    PubMed

    Edwards, J P; Heath, D J

    1983-10-01

    The estuarine isopod Sphaeroma rugicauda (Leach) exhibits a diallelic polymorphism at the locus coding for the enzyme Pgi. An investigation carried out during the animal's breeding season (June-July) in 1979 and 1980 indicated that the animals were mating at random. It also showed the s/s-homozygote females to be the earliest to release offspring and to be the most fecund of the three genotypes (f/f, f/s and s/s). Further, data from the wild population in 1980 and laboratory experiments indicated that male s-gametes were selected against in s/s females, resulting in offspring ratio distortions in f/s (male) X s/s (female) crosses, in favour of heterozygotes. The net effect of these selective pressures did not, however, significantly alter the genotype frequencies (found in the offspring) from expected values.

  9. Gamete-associated flavobacteria of the oviparous Chinook salmon (Oncorhynchus tshawytscha) in lakes Michigan and Huron, North America.

    PubMed

    Loch, Thomas P; Faisal, Mohamed

    2016-07-01

    Flavobacterial diseases, caused by multiple members of the Family Flavobacteriaceae, elicit serious losses in wild and farmed fish around the world. Flavobacteria are known to be transmitted horizontally; however, vertical transmission has been suspected but proven only for one fish-pathogenic flavobacterial species (e.g., Flavobacterium psychrophilum). Herein, we report on the isolation and molecular identification of multiple Flavobacterium and Chryseobacterium taxa from the ovarian fluid and eggs of feral Great Lakes Chinook salmon (Oncorhynchus tshawytscha). Identified egg- and ovarian fluid-associated flavobacteria were either well-known flavobacterial fish pathogens (e.g., F. psychrophilum and F. columnare), most similar to emerging fish-associated flavobacteria (e.g., F. spartansii, F. tructae, F. piscis, C. piscium, C. scophthalmum), or were distinct from all other described Chryseobacterium and Flavobacterium spp., as determined by phylogenetic analyses using neighbor-joining, Bayesian, and Maximum Likelihood methodologies. The gamete-associated flavobacteria fell into three groups (e.g., those that were recovered from the ovarian fluid but not eggs; those that were recovered from the ovarian fluid and eggs; and those that were recovered from eggs but not ovarian fluid), a portion of which were recovered from eggs that were surface disinfected with iodophor at the commonly used dose and duration for egg disinfection. Some gamete-associated flavobacteria were also found in renal, splenic, and neurological tissues. Systemic polymicrobial infections comprised of F. psychrophilum and F. columnare were also detected at nearly an 11% prevalence. This study highlights the potential role that sexual products of female Great Lakes Chinook salmon may play in the transmission of fish-associated flavobacteria. PMID:27350613

  10. Differential Replication of Two Chloroplast Genome Forms in Heteroplasmic Chlamydomonas reinhardtii Gametes Contributes to Alternative Inheritance Patterns

    PubMed Central

    Nishimura, Yoshiki; Stern, David B.

    2010-01-01

    Two mechanisms for chloroplast DNA replication have been revealed through the study of an unusual heteroplasmic strain of the green alga Chlamydomonas reinhardtii. Heteroplasmy is a state in which more than one genome type occurs in a mitochondrion or chloroplast. The Chlamydomonas strain spa19 bears two distinct chloroplast genomes, termed PS+ and PS−. PS+ genomes predominate and are stably maintained in vegetative cells, despite their lack of known replication origins. In sexual crosses with spa19 as the mating type plus parent, however, PS+ genomes are transmitted in only ∼25% of tetrads, whereas the PS− genomes are faithfully inherited in all progeny. In this research, we have explored the mechanism underlying this biased uniparental inheritance. We show that the relative reduction and dilution of PS+ vs. PS− genomes takes place during gametogenesis. Bromodeoxyuridine labeling, followed by immunoprecipitation and PCR, was used to compare replication activities of PS+ and PS− genomes. We found that the replication of PS+ genomes is specifically suppressed during gametogenesis and germination of zygospores, a phenomenon that also was observed when spa19 cells were treated with rifampicin, an inhibitor of the chloroplast RNA polymerase. Furthermore, when bromodeoxyuridine incorporation was compared at 11 sites within the chloroplast genome between vegetative cells, gametes, and rifampicin-treated cells by quantitative PCR, we found that incorporation was often reduced at the same sites in gametes that were also sensitive to rifampicin treatment. We conclude that a transcription-mediated form of DNA replication priming, which may be downregulated during gametogenesis, is indispensable for robust maintenance of PS+ genomes. These results highlight the potential for chloroplast genome copy number regulation through alternative replication strategies. PMID:20519744

  11. Exposure of Paracentrotus lividus male gametes to engineered nanoparticles affects skeletal bio-mineralization processes and larval plasticity.

    PubMed

    Gambardella, Chiara; Ferrando, Sara; Morgana, Silvia; Gallus, Lorenzo; Ramoino, Paola; Ravera, Silvia; Bramini, Mattia; Diaspro, Alberto; Faimali, Marco; Falugi, Carla

    2015-01-01

    The aim of this study is to contribute to the understanding of the mechanisms underlying nanoparticle (NP)-induced embryotoxicity in aquatic organisms. We previously demonstrated that exposure of male gametes to NPs causes non-dose-dependent skeletal damage in sea urchin (Paracentrotus lividus) larvae. In the present study, the molecular mechanisms responsible for these anomalies in sea urchin development from male gametes exposed to cobalt (Co), titanium dioxide (TiO2) and silver (Ag) NPs were investigated by histochemical, immunohistochemical and Western blot analyses. P. lividus sperm were exposed to different NP concentrations (from 0.0001 to 1 mg/L). The distribution of molecules related to skeletogenic cell identification, including ID5 immunoreactivity (IR), wheat germ agglutinin (WGA) affinity and fibronectin (FN) IR, were investigated by confocal laser scanning microscopy at the gastrula (24 h) and pluteus (72 h) stages. Our results identified a spatial correspondence among PMCs, ID5 IR and WGA affinity sites. The altered FN pattern suggests that it is responsible for the altered skeletogenic cell migration, while the Golgi apparatus of the skeletogenic cells, denoted by their WGA affinity, shows different aspects according to the degree of anomalies caused by NP concentrations. The ID5 IR, a specific marker of skeletogenic cells in sea urchin embryos (in particular of the msp130 protein responsible for Ca(2+) and Mg(2+) mineralization), localized in the cellular strands prefiguring the skeletal rods in the gastrula stage and, in the pluteus stage, was visible according to the degree of mineralization of the skeleton. In conclusion, the present study suggests that the investigated NPs suspended in seawater interfere with the bio-mineralization processes in marine organisms, and the results of this study offer a new series of specific endpoints for the mechanistic understanding of NP toxicity. PMID:25481784

  12. Modeling the interaction of gametes and embryos with the maternal genital tract: from in vivo to in silico.

    PubMed

    Van Soom, A; Vandaele, L; Peelman, L J; Goossens, K; Fazeli, A

    2010-04-01

    Understanding the complex interaction between gametes or embryos and the maternal genital tract requires the use of experimental models. The selection of the right model is an important task to undertake, and despite many new developments in this area, an ideal model system has not yet been developed. In this review article, we focus on how the most appropriate model species and model system can be selected, each with its particular advantages and disadvantages. Selection criteria need to be based on the evaluation of the aim of the experiment, the tools that are available to the scientist, and the ethics that are involved in working with particular animal species and model systems. Society and politics direct scientists to "Refine, Reduce, and Replace" the use of experimental animals, which means that the use of in vivo models is increasingly being discouraged. An in vivo model allows experimentation in the full biological environment of a living organism. In contrast with in vivo models, in vitro models are less complex and are abstracts of in vivo systems, leading often to results that are different from the in vivo situation. If an investigator could understand all the components of a complex biological system and re-create them as individual smaller models in a computer, he or she could create in silico models that would completely represent the complexity of in vivo models. We predict that in the future, in silico modeling will be the natural departure from in vivo, in situ, and in vitro modeling approaches. In addition to numerous advantages that this modeling approach can bring to studying maternal interaction with gametes and embryo, it is perhaps the only true alternative method to animal experimentation.

  13. Itinerant ferromagnetism in fermionic systems with SP (2 N) symmetry

    NASA Astrophysics Data System (ADS)

    Yang, Wang; Wu, Congjun

    The Ginzburg-Landau free energy of systems with SP (2 N) symmetry describes a second order phase transition on the mean field level, since the Casimir invariants of the SP (2 N) group can be only of even order combinations of the generators of the SP (2 N) group. This is in contrast with systems having the SU (N) symmetry, where the allowance of cubic term generally makes the phase transition into first order. In this work, we consider the Hertz-Millis type itinerant ferromagnetism in an interacting fermionic system with SP (2 N) symmetry, where the ferromagnetic orders are enriched by the multi-component nature of the system. The quantum criticality is discussed near the second order phase transition point.

  14. Packing density of HS(CH2)(n)COOH self-assembled monolayers.

    PubMed

    Snow, A W; Jernigan, G G; Ancona, M G

    2011-12-01

    Self-assembled monolayers (SAMs) of HS(CH(2))(n)COOH, n = 5, 10, 15 deposited from ethanol solution onto gold are prepared by five approaches, and their packing densities are evaluated by X-ray photoelectron spectroscopy (XPS) measurements. The five approaches are: (1) direct deposition; (2) acetic-acid-assisted deposition; (3) butyl-amine-assisted deposition; (4) displacement of a preformed HS(CH(2))(n)CH(3) (n = 5, 10, 15) SAMs; and (5) co-deposition with HS(CH(2))(n)CH(3) (n = 5, 10, 15). Packing density metrics are calculated from measurements of SAM and substrate photoemission intensities and their attenuations by two methods. In one case the attenuated photoemissions are expressed as a ratio relative to comparable measurements on an experimental HS(CH(2))(n)CH(3) model system. In the other case a new method is introduced where a calculated attenuation based on theoretical random coil and extended chain models is used as the reference to determine a packing density fraction. Packing densities are also correlated with the S2p(Au-bonded):Au4f peak area ratios and with shifts in the C1s binding energies. SAMs prepared by the direct deposition are a partial multilayer where a second molecular layer is physisorbed onto the SAM and not removable by solvent washing. The addition of acetic acid to the deposition solution disrupts dimer associations of HS(CH(2))(n)COOH in solution and at the surface of the monolayer and yields the most ordered monolayer with the highest density of -COOH groups. The addition of butyl amine results in a labile ammonium carbonate ion pair formation but results in a lower packing density in the SAM. The displacement of the preformed HS(CH(2))(n)CH(3) SAM and the co-deposition of HS(CH(2))(n)CH(3) with HS(CH(2))(n)COOH result in SAMs with little incorporation of the -COOH component.

  15. Development of novel chemical synthetic routes for nanocrystalline VN, Mo2N, and W2N nitride materials

    NASA Astrophysics Data System (ADS)

    Mishra, Pragnya Paramita; Panda, Rabi Narayan

    2015-06-01

    In this study, novel synthetic routes for the synthesis of VN, Mo2N and W2N binary nitrides have been presented. We have synthesized new precursors, i.e.V2O5 from citric acid based sol-gel method and Mo, W based ethylenediamine complex which are used for the nitridation experiments using solid urea (NH2CONH2) or ammonia (NH3(g)). We have successfully prepared phase pure nano-dimensional nitride materials. The estimated crystallite sizes and SEM particle sizes were found in the range of 4-16 nm and 111-870 nm, respectively. VN, Mo2N and W2N nitrides crystallize in fcc-cubic structures with the values of lattice parameters; 4.128, 4.165 and 4.175 Å for urea route and 4.112, 4.196 and 4.150Å for ammonia route, respectively.

  16. Holy Mitosis Batman, It's a Gamete: Blending (Bending) the Research Genre.

    ERIC Educational Resources Information Center

    Barton, Fred

    Ken Macrorie coined the term "I Search," which puts the writer at the center of the paper and seeks to put a human face on the data collected. Looking for a way to use the research writing assignment to help students learn to adjust their ideas to different formats by becoming more aware of how different structures can be shaped around their…

  17. Muscle fibre characteristics, enzyme activity and meat colour of wild boar (Sus scrofa s. L.) muscle with 2n=36 compared to those of phenotypically similar crossbreeds (2n=37 and 2n=38).

    PubMed

    Skewes, Oscar; Cádiz, Patricia; Merino, Victoria; Islas, Armando; Morales, Rodrigo

    2014-10-01

    The aim of the present study was to evaluate European wild boar (Sus scrofa s. L.) of chromosomal number 2n=36 in comparison with phenotypically similar crossbreeds (2n=37 and 2n=38) with respect to the muscle fibre characteristics and enzyme activity as well as meat colour in the longissimus dorsi (LD) and semimembranosus (SM) muscles. Differences in the proportion of IIA fibre in the LD muscle between karyotypes 2n=37 and 2n=38 were found. The 2n=36 group showed a lower muscle fibre cross-section area than the 2n=38 karyotype. The meat colour of the 2n=36 karyotype group was redder than 2n=37 and 2n=38. The muscle fibre cross-section area might explain the differences in colour of the meat of wild boar.

  18. Partial nitrogen loss in SrTaO2N and LaTiO2N oxynitride perovskites

    NASA Astrophysics Data System (ADS)

    Chen, Daixi; Habu, Daiki; Masubuchi, Yuji; Torii, Shuki; Kamiyama, Takashi; Kikkawa, Shinichi

    2016-04-01

    SrTaO2N heated in a helium atmosphere began to release nitrogen of approximately 30 at% at 950 °C while maintaining the perovskite structure and its color changed from orange to dark green. Then it decomposed above 1200 °C to a black mixture of Sr1.4Ta0.6O2.73, Ta2N, and Sr5Ta4O15. The second decomposition was not clearly observed when SrTaO2N was heated in a nitrogen atmosphere below 1550 °C. After heating at 1500 °C for 3 h under a 0.2 MPa nitrogen atmosphere, the perovskite product became dark green and conductive. Structure refinement results suggested that the product was a mixture of tetragonal and cubic perovskites with a decreased ordering of N3-/O2-. The sintered body was changed to an n-type semiconductor after a partial loss of nitrogen to be reduced from the originally insulating SrTaO2N perovskite lattice. LaTiO2N was confirmed to have a similar cis-configuration of the TiO4N2 octahedron as that of TaO4N2 in SrTaO2N. It also released some of its nitrogen at 800 °C changing its color from brown to black and then decomposed to a mixture of LaTiO3, La2O3, and TiN at 1100 °C. These temperatures are lower than those in SrTaO2N.

  19. Quantum Discord of 2 n -Dimensional Bell-Diagonal States

    NASA Astrophysics Data System (ADS)

    Jafarizadeh, M. A.; Karimi, N.; Amidi, D.; Zahir Olyaei, H.

    2016-03-01

    In this study, using the concept of relative entropy as a distance measure of correlations we investigate the important issue of evaluating quantum correlations such as entanglement, dissonance and classical correlations for 2 n -dimensional Bell-diagonal states. We provide an analytical technique, which describes how we find the closest classical states(CCS) and the closest separable states(CSS) for these states. Then analytical results are obtained for quantum discord of 2 n -dimensional Bell-diagonal states. As illustration, some special cases are examined. Finally, we investigate the additivity relation between the different correlations for the separable generalized Bloch sphere states.

  20. Successful pregnancy outcome following gamete intra-Fallopian transfer in a patient with Müllerian dysgenesis.

    PubMed

    Lee, Colin S S; Lie, Aldrin T M

    2012-05-01

    A 29-year-old lady with Müllerian dysgenesis was keen to have a baby. Clinically, she was medium built with well-developed secondary female sexual characteristics. There was a short and blind vagina. She had undergone surgery for an imperforated hymen. Her FSH and LH concentrations were normal. Laparoscopy revealed a patent right Fallopian tube, a rudimentary right uterus and extensive pelvic endometriosis. She subsequently underwent gamete intra-Fallopian transfer (GIFT). Oocyte retrieval was carried out laparoscopically and a total of nine oocytes were retrieved. Four of the oocytes were transferred together with motile spermatozoa into the right Fallopian tube and the remaining five oocytes were inseminated with spermatozoa for IVF. Three embryos resulted and were frozen. She subsequently developed moderate ovarian hyperstimulation syndrome. Serum β-human chorionic gonadotrophin concentration 14 days after GIFT was 1612 IU/l. Her antenatal care was relatively uneventful until 31 weeks of gestation when she was diagnosed to have intrauterine growth retardation and oligohydramnios. She then underwent an emergency Caesarean section at 32 weeks of pregnancy delivering a normal baby. This case study describes a successful pregnancy outcome following gamete intra-Fallopian transfer (GIFT) in a woman with malformation of the vagina (Müllerian dysgenesis). A 29-year-old lady with Müllerian dysgenesis diagnosed at 16 years of age was keen to become pregnant. Upon examination, a decision was made for a William's vulvovaginoplasty but as the patient was indecisive the surgery was deferred. Clinically, she is a medium-built lady with well-developed secondary female sexual characteristics. There was a short and blind vagina. Her serum FSH and LH concentrations were normal. Laparoscopy revealed a patent right Fallopian tube, a rudimentary right uterus and extensive pelvic endometriosis. She subsequently underwent GIFT. Nine oocytes were retrieved through laparoscopy. Four

  1. The role of OsMSH4 in male and female gamete development in rice meiosis

    PubMed Central

    Wang, Chaolong; Wang, Yang; Cheng, Zhijun; Zhao, Zhigang; Chen, Jun; Sheng, Peike; Yu, Yang; Ma, Weiwei; Duan, Erchao; Wu, Fuqing; Liu, Linglong; Qin, Ruizhen; Zhang, Xin; Guo, Xiuping; Wang, Jiulin; Jiang, Ling; Wan, Jianmin

    2016-01-01

    Meiosis is essential for gametogenesis in sexual reproduction in rice (Oryza sativa L.). We identified a MutS-homolog (MSH) family gene OsMSH4 in a trisomic plant. Cytological analysis showed that developments of both pollen and embryo sacs in an Osmsh4 mutant were blocked due to defective chromosome pairing. Compared with the wild type, the Osmsh4 mutant displayed a significant ~21.9% reduction in chiasma frequency, which followed a Poisson distribution, suggesting that class I crossover formation in the mutant was impaired. Temporal and spatial expression pattern analyses showed that OsMSH4 was preferentially expressed in meiocytes during their meiosis, indicating a critical role in gametogenesis. Subcellular localization showed that OsMSH4–green fluorescent protein was predominantly located in the nucleus. OsMSH4 could interact with another MSH member (OsMSH5) through the N-terminus and C-terminus, respectively. Direct physical interaction between OsMSH5, OsRPA1a, OsRPA2b, OsRPA1c, and OsRPA2c was identified by yeast two-hybrid assays and further validated by pull-down assays. Our results supported the conclusion that the OsMSH4/5 heterodimer plays a key role in regulation of crossover formation during rice meiosis by interaction with the RPA complex. PMID:26712826

  2. The role of OsMSH4 in male and female gamete development in rice meiosis.

    PubMed

    Wang, Chaolong; Wang, Yang; Cheng, Zhijun; Zhao, Zhigang; Chen, Jun; Sheng, Peike; Yu, Yang; Ma, Weiwei; Duan, Erchao; Wu, Fuqing; Liu, Linglong; Qin, Ruizhen; Zhang, Xin; Guo, Xiuping; Wang, Jiulin; Jiang, Ling; Wan, Jianmin

    2016-03-01

    Meiosis is essential for gametogenesis in sexual reproduction in rice (Oryza sativa L.). We identified a MutS-homolog (MSH) family gene OsMSH4 in a trisomic plant. Cytological analysis showed that developments of both pollen and embryo sacs in an Osmsh4 mutant were blocked due to defective chromosome pairing. Compared with the wild type, the Osmsh4 mutant displayed a significant ~21.9% reduction in chiasma frequency, which followed a Poisson distribution, suggesting that class I crossover formation in the mutant was impaired. Temporal and spatial expression pattern analyses showed that OsMSH4 was preferentially expressed in meiocytes during their meiosis, indicating a critical role in gametogenesis. Subcellular localization showed that OsMSH4-green fluorescent protein was predominantly located in the nucleus. OsMSH4 could interact with another MSH member (OsMSH5) through the N-terminus and C-terminus, respectively. Direct physical interaction between OsMSH5, OsRPA1a, OsRPA2b, OsRPA1c, and OsRPA2c was identified by yeast two-hybrid assays and further validated by pull-down assays. Our results supported the conclusion that the OsMSH4/5 heterodimer plays a key role in regulation of crossover formation during rice meiosis by interaction with the RPA complex.

  3. Tunable C2N Membrane for High Efficient Water Desalination.

    PubMed

    Yang, Yanmei; Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2016-07-07

    Water scarcity represents one of the most serious global problems of our time and challenges the advancements in desalination techniques. Although water-filtering architectures based on graphene have greatly advanced the approach to high performance desalination membranes, the controlled-generation of nanopores with particular diameter is tricky and has stunted its wide applications. Here, through molecular dynamic simulations and first-principles calculations, we propose that the recently reported graphene-like carbon nitride (g-C2N) monolayer can serve as high efficient filters for water desalination. Taking the advantages of the intrisic nanoporous structure and excellent mechanical properties of g-C2N, high water transparency and strong salt filtering capability have been demonstrated in our simulations. More importantly, the "open" and "closed" states of the g-C2N filter can be precisely regulated by tensile strain. It is found that the water permeability of g-C2N is significantly higher than that reported for graphene filters by almost one order of magnitude. In the light of the abundant family of graphene-like carbon nitride monolayered materials, our results thus offer a promising approach to the design of high efficient filteration architectures.

  4. Tunable C2N Membrane for High Efficient Water Desalination.

    PubMed

    Yang, Yanmei; Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2016-01-01

    Water scarcity represents one of the most serious global problems of our time and challenges the advancements in desalination techniques. Although water-filtering architectures based on graphene have greatly advanced the approach to high performance desalination membranes, the controlled-generation of nanopores with particular diameter is tricky and has stunted its wide applications. Here, through molecular dynamic simulations and first-principles calculations, we propose that the recently reported graphene-like carbon nitride (g-C2N) monolayer can serve as high efficient filters for water desalination. Taking the advantages of the intrisic nanoporous structure and excellent mechanical properties of g-C2N, high water transparency and strong salt filtering capability have been demonstrated in our simulations. More importantly, the "open" and "closed" states of the g-C2N filter can be precisely regulated by tensile strain. It is found that the water permeability of g-C2N is significantly higher than that reported for graphene filters by almost one order of magnitude. In the light of the abundant family of graphene-like carbon nitride monolayered materials, our results thus offer a promising approach to the design of high efficient filteration architectures. PMID:27384666

  5. Transistor step stress program for JANTX2N4150

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Reliability analysis of the transistor JANTX2N4150 manufactured by General Semiconductor and Transitron is reported. The discrete devices were subjected to power and temperature step stress tests and then to electrical tests after completing the power/temperature step stress point. Control sample units were maintained for verification of the electrical parametric testing. Results are presented.

  6. Tunable C2N Membrane for High Efficient Water Desalination

    PubMed Central

    Yang, Yanmei; Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2016-01-01

    Water scarcity represents one of the most serious global problems of our time and challenges the advancements in desalination techniques. Although water-filtering architectures based on graphene have greatly advanced the approach to high performance desalination membranes, the controlled-generation of nanopores with particular diameter is tricky and has stunted its wide applications. Here, through molecular dynamic simulations and first-principles calculations, we propose that the recently reported graphene-like carbon nitride (g-C2N) monolayer can serve as high efficient filters for water desalination. Taking the advantages of the intrisic nanoporous structure and excellent mechanical properties of g-C2N, high water transparency and strong salt filtering capability have been demonstrated in our simulations. More importantly, the “open” and “closed” states of the g-C2N filter can be precisely regulated by tensile strain. It is found that the water permeability of g-C2N is significantly higher than that reported for graphene filters by almost one order of magnitude. In the light of the abundant family of graphene-like carbon nitride monolayered materials, our results thus offer a promising approach to the design of high efficient filteration architectures. PMID:27384666

  7. Tunable C2N Membrane for High Efficient Water Desalination

    NASA Astrophysics Data System (ADS)

    Yang, Yanmei; Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2016-07-01

    Water scarcity represents one of the most serious global problems of our time and challenges the advancements in desalination techniques. Although water-filtering architectures based on graphene have greatly advanced the approach to high performance desalination membranes, the controlled-generation of nanopores with particular diameter is tricky and has stunted its wide applications. Here, through molecular dynamic simulations and first-principles calculations, we propose that the recently reported graphene-like carbon nitride (g-C2N) monolayer can serve as high efficient filters for water desalination. Taking the advantages of the intrisic nanoporous structure and excellent mechanical properties of g-C2N, high water transparency and strong salt filtering capability have been demonstrated in our simulations. More importantly, the “open” and “closed” states of the g-C2N filter can be precisely regulated by tensile strain. It is found that the water permeability of g-C2N is significantly higher than that reported for graphene filters by almost one order of magnitude. In the light of the abundant family of graphene-like carbon nitride monolayered materials, our results thus offer a promising approach to the design of high efficient filteration architectures.

  8. The cytoplasmic domain of the gamete membrane fusion protein HAP2 targets the protein to the fusion site in Chlamydomonas and regulates the fusion reaction.

    PubMed

    Liu, Yanjie; Pei, Jimin; Grishin, Nick; Snell, William J

    2015-03-01

    Cell-cell fusion between gametes is a defining step during development of eukaryotes, yet we know little about the cellular and molecular mechanisms of the gamete membrane fusion reaction. HAP2 is the sole gamete-specific protein in any system that is broadly conserved and shown by gene disruption to be essential for gamete fusion. The wide evolutionary distribution of HAP2 (also known as GCS1) indicates it was present in the last eukaryotic common ancestor and, therefore, dissecting its molecular properties should provide new insights into fundamental features of fertilization. HAP2 acts at a step after membrane adhesion, presumably directly in the merger of the lipid bilayers. Here, we use the unicellular alga Chlamydomonas to characterize contributions of key regions of HAP2 to protein location and function. We report that mutation of three strongly conserved residues in the ectodomain has no effect on targeting or fusion, although short deletions that include those residues block surface expression and fusion. Furthermore, HAP2 lacking a 237-residue segment of the cytoplasmic region is expressed at the cell surface, but fails to localize at the apical membrane patch specialized for fusion and fails to rescue fusion. Finally, we provide evidence that the ancient HAP2 contained a juxta-membrane, multi-cysteine motif in its cytoplasmic region, and that mutation of a cysteine dyad in this motif preserves protein localization, but substantially impairs HAP2 fusion activity. Thus, the ectodomain of HAP2 is essential for its surface expression, and the cytoplasmic region targets HAP2 to the site of fusion and regulates the fusion reaction.

  9. The cytoplasmic domain of the gamete membrane fusion protein HAP2 targets the protein to the fusion site in Chlamydomonas and regulates the fusion reaction

    PubMed Central

    Liu, Yanjie; Pei, Jimin; Grishin, Nick; Snell, William J.

    2015-01-01

    Cell-cell fusion between gametes is a defining step during development of eukaryotes, yet we know little about the cellular and molecular mechanisms of the gamete membrane fusion reaction. HAP2 is the sole gamete-specific protein in any system that is broadly conserved and shown by gene disruption to be essential for gamete fusion. The wide evolutionary distribution of HAP2 (also known as GCS1) indicates it was present in the last eukaryotic common ancestor and, therefore, dissecting its molecular properties should provide new insights into fundamental features of fertilization. HAP2 acts at a step after membrane adhesion, presumably directly in the merger of the lipid bilayers. Here, we use the unicellular alga Chlamydomonas to characterize contributions of key regions of HAP2 to protein location and function. We report that mutation of three strongly conserved residues in the ectodomain has no effect on targeting or fusion, although short deletions that include those residues block surface expression and fusion. Furthermore, HAP2 lacking a 237-residue segment of the cytoplasmic region is expressed at the cell surface, but fails to localize at the apical membrane patch specialized for fusion and fails to rescue fusion. Finally, we provide evidence that the ancient HAP2 contained a juxta-membrane, multi-cysteine motif in its cytoplasmic region, and that mutation of a cysteine dyad in this motif preserves protein localization, but substantially impairs HAP2 fusion activity. Thus, the ectodomain of HAP2 is essential for its surface expression, and the cytoplasmic region targets HAP2 to the site of fusion and regulates the fusion reaction. PMID:25655701

  10. Linking Gene Expression in the Intestine to Production of Gametes Through the Phosphate Transporter PITR-1 in Caenorhabditis elegans

    PubMed Central

    Balklava, Zita; Rathnakumar, Navin D.; Vashist, Shilpa; Schweinsberg, Peter J.; Grant, Barth D.

    2016-01-01

    Inorganic phosphate is an essential mineral for both prokaryotic and eukaryotic cell metabolism and structure. Its uptake into the cell is mediated by membrane-bound transporters and coupled to Na+ transport. Mammalian sodium-dependent Pi cotransporters have been grouped into three families NaPi-I, NaPi-II, and NaPi-III. Despite being discovered more than two decades ago, very little is known about requirements for NaPi-III transporters in vivo, in the context of intact animal models. Here we find that impaired function of the Caenorhabditis elegans NaPi-III transporter, pitr-1, results in decreased brood size and dramatically increased expression of vitellogenin by the worm intestine. Unexpectedly, we found that the effects of pitr-1 mutation on vitellogenin expression in the intestine could only be rescued by expression of pitr-1 in the germline, and not by expression of pitr-1 in the intestine itself. Our results indicate the existence of a signal from the germline that regulates gene expression in the intestine, perhaps linking nutrient export from the intestine to production of gametes by the germline. PMID:27449055

  11. Linking Gene Expression in the Intestine to Production of Gametes Through the Phosphate Transporter PITR-1 in Caenorhabditis elegans.

    PubMed

    Balklava, Zita; Rathnakumar, Navin D; Vashist, Shilpa; Schweinsberg, Peter J; Grant, Barth D

    2016-09-01

    Inorganic phosphate is an essential mineral for both prokaryotic and eukaryotic cell metabolism and structure. Its uptake into the cell is mediated by membrane-bound transporters and coupled to Na(+) transport. Mammalian sodium-dependent Pi cotransporters have been grouped into three families NaPi-I, NaPi-II, and NaPi-III. Despite being discovered more than two decades ago, very little is known about requirements for NaPi-III transporters in vivo, in the context of intact animal models. Here we find that impaired function of the Caenorhabditis elegans NaPi-III transporter, pitr-1, results in decreased brood size and dramatically increased expression of vitellogenin by the worm intestine. Unexpectedly, we found that the effects of pitr-1 mutation on vitellogenin expression in the intestine could only be rescued by expression of pitr-1 in the germline, and not by expression of pitr-1 in the intestine itself. Our results indicate the existence of a signal from the germline that regulates gene expression in the intestine, perhaps linking nutrient export from the intestine to production of gametes by the germline. PMID:27449055

  12. Effects of temperature on gamete longevity and fertilization success in two sea urchin species, Echinometra mathaei and Tripneustes gratilla.

    PubMed

    Rahman, Md Saifur; Tsuchiya, Makoto; Uehara, Tsuyoshi

    2009-01-01

    We investigated gamete longevity in two sea urchin species, Echinometra mathaei (Em) and Tripneustes gratilla (Tg), via laboratory experiments. The longevity of dry sperm at different ages (6, 12, 18, 24, and 30 h after collection) was tested at 20 degrees, 25 degrees, and 30 degrees C. Sperm viability was determined by the percent cleavage of eggs after in-vitro fertilization. Dry sperm of Em remained viable longer than dry sperm of Tg at all temperatures. The viability of dilute sperm and eggs was also determined at 20 degrees, 25 degrees, and 30 degrees C over varying durations (for sperm, 5, 45, and 85 min; for eggs, 1, 3, 6, 12, and 24 h). The viability of dilute Em sperm remained relatively constant over time (nearly 100%) at 20 degrees and 25 degrees C, but decreased rapidly at 30 degrees C. The viability of Tg sperm declined gradually over time at 20 degrees C and decreased sharply at 25 degrees and 30 degrees C. Eggs of Em and Tg remained fertilizable for 12 and 6 h, respectively. Most eggs of Em and Tg underwent normal development when exposed for less than 6 h and 3 h, respectively. These results may illuminate the different fertilization strategies of these two sea urchin species.

  13. Gamete derivation from embryonic stem cells, induced pluripotent stem cells or somatic cell nuclear transfer-derived embryonic stem cells: state of the art

    PubMed Central

    Easley, Charles A.; Simerly, Calvin R.; Schatten, Gerald

    2015-01-01

    Generating gametes from pluripotent stem cells (PSCs) has many scientific justifications and several biomedical rationales. Here, we consider several strategies for deriving gametes from PSCs from mice and primates (human and non-human) and their anticipated strengths, challenges and limitations. Although the ‘Weismann barrier’, which separates the mortal somatic cell lineages from the potentially immortal germline, has long existed, breakthroughs first in mice and now in humans are artificially creating germ cells from somatic cells. Spermatozoa with full reproductive viability establishing multiple generations of seemingly normal offspring have been reported in mice and, in humans, haploid spermatids with correct parent-of-origin imprints have been obtained. Similar progress with making oocytes has been published using mouse PSCs differentiated in vitro into primordial germ cells, which are then cultured after xenografting reconstructed artificial ovaries. Progress in making human oocytes artificially is proving challenging. The usefulness of these artificial gametes, from assessing environmental exposure toxicity to optimising medical treatments to prevent negative off-target effects on fertility, may prove invaluable, as may basic discoveries on the fundamental mechanisms of gametogenesis. PMID:25472048

  14. Intracellular cotrafficking of factor VIII and von Willebrand factor type 2N variants to storage organelles.

    PubMed

    van den Biggelaar, Maartje; Meijer, Alexander B; Voorberg, Jan; Mertens, Koen

    2009-03-26

    Weibel-Palade bodies (WPBs) are the endothelial storage organelles that are formed upon von Willebrand factor (VWF) expression. Apart from VWF, WPBs contain a variety of hemostatic and inflammatory proteins. Some of these are thought to be targeted to WPBs by directly interacting with VWF in the secretory pathway. Previous studies have demonstrated that coexpression of factor VIII (FVIII) with VWF results in costorage of both proteins. However, whether cotrafficking is driven by intracellular FVIII-VWF assembly has remained unclear. We now have addressed this issue using recombinant VWF type 2N variants that are known to display reduced FVIII binding in the circulation. Binding studies using purified fluorescent FVIII and VWF type 2N variants revealed FVIII binding defects varying from moderate (Arg854Gln, Cys1060Arg) to severe (Arg763Gly, Thr791Met, Arg816Trp). Upon expression in HEK293 cells, all VWF variants induced formation of WPB-like organelles that were able to recruit P-selectin, as well as FVIII. WPBs containing FVIII did not display their typical elongated shape, suggesting that FVIII affects the organization of VWF tubules therein. The finding that VWF type 2N variants are still capable of cotargeting FVIII to storage granules implies that trafficking of WPB cargo proteins does not necessarily require high-affinity assembly with VWF. PMID:19088379

  15. Automated HPLC separation of endohedral metallofullerene ScC{sub 2n} and YC{sub 2n} fractions

    SciTech Connect

    Stevenson, S.; Dorn, H.C.; Burbank, P.; Harich, K.; Haynes, J. Jr.; Kiang, C.H.; Salem, J.R.; DeVries, M.S.; Loosdrecht, P.H.M. van; Johnson, R.D.; Yannoni, C.S.; Bethune, D.S.

    1994-09-01

    We describe an automated HPLC separation of the endohedral metallofullerenes such as SCC{sub 2n} and YC{sub 2n} from empty-cage fullerenes utilizing two polystyrene chromatographic columns (500 and 1000 A) in series. Rapid separation of the metallofullerene fraction from the empty-cage fullerenes (e.g., C{sub 60}) under anaerobic conditions is achieved. For the isolated SCC{sub 2n} fraction, all even-carbon-membered species from Sc{sub 2}C{sub 74} to Sc{sub 2}C{sub 104} were identified by negative-ion chemical ionization mass spectrometry. In addition, Sc{sub 3}C{sub 82} was a prominent component of this fraction. For the separated YC{sub 2n} sample, the mass spectral data indicate the presence of YC{sub 82} and all even-carbon-numbered diyttrium species from Y{sub 2}C{sub 82} to Y{sub 2}C{sub 104}. 14 refs., 7 figs.

  16. Antifungal properties of 2-n-alkyn-1-ols.

    PubMed

    Gershon, H; Rowe, G E; Santore, R C; Gilbertson, J R; Langkamp, H

    1984-12-01

    Fourteen 2-n-alkynols (C3-C14, C16, and C18) were tested against Aspergillus oryzae, Aspergillus niger, Trichoderma viride, and Myrothecium verrucaria in Sabouraud dextrose agar at pH 5.6 and 7.0. Toxicity to Candida albicans, Candida tropicalis, Trichophyton mentagrophytes, and Mucor mucedo was determined in the same medium at pH 5.6 and 7.0 in the absence and presence of 10% beef serum. Fungitoxicity was strongly influenced by chain length, slightly by the pH of the medium, and significantly by the presence of beef serum. 2-n-Undecyn-1-ol was the most active member of the series, and there was marked synergism between it and ketoconazole.

  17. The stress response in gametes and embryos after paternal chemical exposures

    SciTech Connect

    Hales, Barbara F. . E-mail: barbara.hales@mcgill.ca; Aguilar-Mahecha, Adriana; Robaire, Bernard

    2005-09-01

    There is increasing concern that paternal exposure to toxic chemicals impacts negatively on progeny outcome. Exposure of male rats to a model male-mediated developmental toxicant and anticancer alkylating agent, cyclophosphamide, resulted in increased pre- and post-implantation loss, as well as in malformations. We hypothesize that the stage specificity of the effects of paternal cyclophosphamide exposure on progeny depends on the ability of germ cells to respond to stress, repair DNA or undergo apoptosis. Acute high dose exposure of male rats to cyclophosphamide increased the expression of heat shock proteins and DNA repair genes, predominantly in round spermatids. In contrast, chronic low dose treatment dramatically decreased the expression of stress response genes in pachytene spermatocytes and round spermatids, but not in elongated spermatids; this reduced ability to respond to stress may allow damage to accumulate, resulting in altered sperm function. Increased DNA damage was maximal 3 weeks after drug exposure, during spermiogenesis, a key point in sperm chromatin remodelling. Drug exposure for 9 weeks increased the frequency of spermatozoa with chromosome 4 disomy and nullisomy. DNA damage found in cyclophosphamide-exposed spermatozoa was imparted to the newly fertilized zygote. Drug-exposed spermatozoa decondensed more rapidly than control spermatozoa and male pronuclear formation was earlier. RNA synthesis was higher in 1-cell embryos sired by drug-treated fathers than in controls. Significantly, the profile of gene expression was altered in embryos sired by drug-treated males as early as the 1-cell stage. Thus, exposure of male rats to cyclophosphamide altered male germ cell quality with a consequent temporal and spatial disruption of the zygotic genome activation.

  18. Phase 2 N01 Program - Cancer Imaging Program

    Cancer.gov

    The Phase 2 N01 Program is a CTEP-CIP collaboration includes 7 contractors, most of whom consist of multi-institutional consortia, and includes a total of 22 NCI-designated Cancer Centers. These sites carry out early clinical trials with CTEP and CIP-held IND agents, with an emphasis on phase 2 trials, but including phase 1 trials as well. These trials include the evaluation of novel imaging agents and methods to enhance the evaluation of novel therapeutics.

  19. Transistor step stress program for JANTX2N2432A

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Power/temperature step stress was applied to the transistor JANTX2N2432A manufactured by Crystalonics and Texas Instruments. A total of 48 samples from each manufacturer were submitted to the process outlined. In addition, two control sample units were maintained for verification of the electrical parametric testing. All test samples were subjected to the electrical tests after completing the prior power/temperature step stress point.

  20. Transistor step stress program for JANTX2N2219A

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Power/temperature step stress was applied to the dual transistor JANTX2N2219A manufactured by Texas Instruments and National Semiconductor. A total of 48 samples from each manufacturer were submitted to the process outlined. In addition, two control sample units were maintained for verification of the electrical parametric testing. All test samples were subjected to electrical tests after completing the prior power/temperature step stress point.

  1. Transistor step stress program for JANTX2N2060

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The effect of power/temperature step stress when applied to the dual transistor JANTX2N2060 manufactured by Raytheon and Motorola is reported. A total of 48 samples from each manufacturer were submitted to the process. In addition, two control sample units were maintained for verification of the electrical parametric testing. All test samples were subjected to the electrical tests after completing the prior power/temperature step stress point. Results are given.

  2. Quantum indistinguishability from general representations of SU(2n)

    NASA Astrophysics Data System (ADS)

    Harrison, J. M.; Robbins, J. M.

    2004-04-01

    A treatment of the spin-statistics relation in nonrelativistic quantum mechanics due to Berry and Robbins [Proc. R. Soc. London Ser. A 453, 1771-1790 (1997)] is generalized within a group-theoretical framework. The construction of Berry and Robbins is reformulated in terms of certain locally flat vector bundles over n-particle configuration space. It is shown how families of such bundles can be constructed from irreducible representations of the group SU(2n). The construction of Berry and Robbins, which leads to a definite connection between spin and statistics (the physically correct connection), is shown to correspond to the completely symmetric representations. The spin-statistics connection is typically broken for general SU(2n) representations, which may admit, for a given value of spin, both Bose and Fermi statistics, as well as parastatistics. The determination of the allowed values of the spin and statistics reduces to the decomposition of certain zero-weight representations of a (generalized) Weyl group of SU(2n). A formula for this decomposition is obtained using the Littlewood-Richardson theorem for the decomposition of representations of U(m+n) into representations of U(m)×U(n).

  3. Anomalous effect of vanadium boride seeding on thermoelectric properties of YB{sub 22}C{sub 2}N

    SciTech Connect

    Prytuliak, A.; Maruyama, S.; Mori, T.

    2013-05-15

    Highlights: ► We doped YB{sub 22}C{sub 2}N; the long awaited n-type counterpart to p-type boron carbide. ► VB{sub 2} seeding of YB{sub 22}C{sub 2}N showed striking results. ► Thermal treatment effects led to VB{sub 2} being intrinsically doped. ► Large increase of both Seebeck coefficient and electrical conductivity was obtained. - Abstract: Vanadium boride seeded YB{sub 22}C{sub 2}N were synthesized and the thermoelectric properties investigated. YB{sub 22}C{sub 2}N is representative of the series of rare earth borocarbonitrides which is the potential long awaited n-type counterpart to p-type boron carbide. VB{sub 2} seeded samples of YB{sub 22}C{sub 2}N were prepared using VB{sub 2} directly as an initial additive and V{sub 2}O{sub 3} which also results in formation of vanadium diboride in the final product. The resistivity and Seebeck coefficient of samples were measured in the temperature range of 323 K to 1073 K. A dramatic effect of thermal treatment on the Seebeck coefficient of VB{sub 2} seeded samples was observed, and it is indicated that there is possible partial intrinsic doping of vanadium into YB{sub 22}C{sub 2}N. VB{sub 2} is revealed to be a promising additive to improve the thermoelectric properties of YB{sub 22}C{sub 2}N. An enhancement of more than 220% of the maximum absolute value of the Seebeck coefficient was obtained while the resistivity was also reduced considerably.

  4. Selection and demographic history shape the molecular evolution of the gamete compatibility protein bindin in Pisaster sea stars

    PubMed Central

    Popovic, Iva; Marko, Peter B; Wares, John P; Hart, Michael W

    2014-01-01

    Reproductive compatibility proteins have been shown to evolve rapidly under positive selection leading to reproductive isolation, despite the potential homogenizing effects of gene flow. This process has been implicated in both primary divergence among conspecific populations and reinforcement during secondary contact; however, these two selective regimes can be difficult to discriminate from each other. Here, we describe the gene that encodes the gamete compatibility protein bindin for three sea star species in the genus Pisaster. First, we compare the full-length bindin-coding sequence among all three species and analyze the evolutionary relationships between the repetitive domains of the variable second bindin exon. The comparison suggests that concerted evolution of repetitive domains has an effect on bindin divergence among species and bindin variation within species. Second, we characterize population variation in the second bindin exon of two species: We show that positive selection acts on bindin variation in Pisaster ochraceus but not in Pisaster brevispinus, which is consistent with higher polyspermy risk in P. ochraceus. Third, we show that there is no significant genetic differentiation among populations and no apparent effect of sympatry with congeners that would suggest selection based on reinforcement. Fourth, we combine bindin and cytochrome c oxidase 1 data in isolation-with-migration models to estimate gene flow parameter values and explore the historical demographic context of our positive selection results. Our findings suggest that positive selection on bindin divergence among P. ochraceus alleles can be accounted for in part by relatively recent northward population expansions that may be coupled with the potential homogenizing effects of concerted evolution. PMID:24967076

  5. Selection and demographic history shape the molecular evolution of the gamete compatibility protein bindin in Pisaster sea stars.

    PubMed

    Popovic, Iva; Marko, Peter B; Wares, John P; Hart, Michael W

    2014-05-01

    Reproductive compatibility proteins have been shown to evolve rapidly under positive selection leading to reproductive isolation, despite the potential homogenizing effects of gene flow. This process has been implicated in both primary divergence among conspecific populations and reinforcement during secondary contact; however, these two selective regimes can be difficult to discriminate from each other. Here, we describe the gene that encodes the gamete compatibility protein bindin for three sea star species in the genus Pisaster. First, we compare the full-length bindin-coding sequence among all three species and analyze the evolutionary relationships between the repetitive domains of the variable second bindin exon. The comparison suggests that concerted evolution of repetitive domains has an effect on bindin divergence among species and bindin variation within species. Second, we characterize population variation in the second bindin exon of two species: We show that positive selection acts on bindin variation in Pisaster ochraceus but not in Pisaster brevispinus, which is consistent with higher polyspermy risk in P. ochraceus. Third, we show that there is no significant genetic differentiation among populations and no apparent effect of sympatry with congeners that would suggest selection based on reinforcement. Fourth, we combine bindin and cytochrome c oxidase 1 data in isolation-with-migration models to estimate gene flow parameter values and explore the historical demographic context of our positive selection results. Our findings suggest that positive selection on bindin divergence among P. ochraceus alleles can be accounted for in part by relatively recent northward population expansions that may be coupled with the potential homogenizing effects of concerted evolution. PMID:24967076

  6. Species and gamete-specific fertilization success of two sea urchins under near future levels of pCO2

    NASA Astrophysics Data System (ADS)

    Sung, Chan-Gyung; Kim, Tae Won; Park, Young-Gyu; Kang, Seong-Gil; Inaba, Kazuo; Shiba, Kogiku; Choi, Tae Seob; Moon, Seong-Dae; Litvin, Steve; Lee, Kyu-Tae; Lee, Jung-Suk

    2014-09-01

    Since the Industrial Revolution, rising atmospheric CO2 concentration has driven an increase in the partial pressure of CO2 in seawater (pCO2), thus lowering ocean pH. We examined the separate effects of exposure of gametes to elevated pCO2 and low pH on fertilization success of the sea urchin Strongylocentrotus nudus. Sperm and eggs were independently exposed to seawater with pCO2 levels ranging from 380 (pH 7.96-8.3) to 6000 ppmv (pH 7.15-7.20). When sperm were exposed, fertilization rate decreased drastically with increased pCO2, even at a concentration of 450 ppmv (pH range: 7.94 to 7.96). Conversely, fertilization of Hemicentrotus pulcherrimus was not significantly changed even when sperm was exposed to pCO2 concentrations as high as 750 ppmv. Exposure of S. nudus eggs to seawater with high pCO2 did not affect fertilization success, suggesting that the effect of increased pCO2 on sperm is responsible for reduced fertilization success. Surprisingly, this result was not related to sperm motility, which was insensitive to pCO2. When seawater was acidified using HCl, leaving pCO2 constant, fertilization success in S. nudus remained high (> 80%) until pH decreased to 7.3. While further studies are required to elucidate the physiological mechanism by which elevated pCO2 impairs sperm and reduces S. nudus fertilization, this study suggests that in the foreseeable future, sea urchin survival may be threatened due to lower fertilization success driven by elevated pCO2 rather than by decreased pH in seawater.

  7. Selection and demographic history shape the molecular evolution of the gamete compatibility protein bindin in Pisaster sea stars.

    PubMed

    Popovic, Iva; Marko, Peter B; Wares, John P; Hart, Michael W

    2014-05-01

    Reproductive compatibility proteins have been shown to evolve rapidly under positive selection leading to reproductive isolation, despite the potential homogenizing effects of gene flow. This process has been implicated in both primary divergence among conspecific populations and reinforcement during secondary contact; however, these two selective regimes can be difficult to discriminate from each other. Here, we describe the gene that encodes the gamete compatibility protein bindin for three sea star species in the genus Pisaster. First, we compare the full-length bindin-coding sequence among all three species and analyze the evolutionary relationships between the repetitive domains of the variable second bindin exon. The comparison suggests that concerted evolution of repetitive domains has an effect on bindin divergence among species and bindin variation within species. Second, we characterize population variation in the second bindin exon of two species: We show that positive selection acts on bindin variation in Pisaster ochraceus but not in Pisaster brevispinus, which is consistent with higher polyspermy risk in P. ochraceus. Third, we show that there is no significant genetic differentiation among populations and no apparent effect of sympatry with congeners that would suggest selection based on reinforcement. Fourth, we combine bindin and cytochrome c oxidase 1 data in isolation-with-migration models to estimate gene flow parameter values and explore the historical demographic context of our positive selection results. Our findings suggest that positive selection on bindin divergence among P. ochraceus alleles can be accounted for in part by relatively recent northward population expansions that may be coupled with the potential homogenizing effects of concerted evolution.

  8. SPECTRAL FUNCTIONS OF A CANONICAL SYSTEM OF ORDER 2n

    NASA Astrophysics Data System (ADS)

    Sakhnovich, A. L.

    1992-02-01

    The author describes a set of pseudospectral functions of the canonical system of differential equations \\displaystyle dW(x,\\,\\lambda)/dx = i\\lambda JH(x)W(x,\\lambda),\\qquad W(0,\\,\\lambda) = E_{2n},where \\displaystyle 0\\leq x\\leq l<\\infty,\\qquad H(x)=H^*(x)\\geq0,\\qquad J=\\begin{bmatrix}0 & E_n\\\\E_n & 0\\end{bmatrix}.In terms of the Hamiltonians H(x), conditions are given under which the pseudospectral functions are spectral functions.

  9. Singlet-assisted supersymmetry breaking for Sp(2N) theories

    NASA Astrophysics Data System (ADS)

    Zhu, Bin; Meng, Kun; Ding, Ran; Li, Qiyi

    2013-07-01

    We investigate local supersymmetry-breaking vacua in s-confining theories with gauge group Sp(2N). By adapting the general recipe developed by Shadmi and Shirman, we construct a realistic model based on dynamics of SQCD coupled with singlets which allows a spontaneously broken supersymmetry. Since the chiral superfields in model have R-charges R = 0 and R = 2 only, the tedious computations of Coleman-Weinberg potential can be greatly alleviated from the lesson of David Shih. We observe that the pseudomoduli fields are stabilized at the origin of moduli space at one-loop order with calculability being preserved.

  10. 6-Propionyl-2-(N,N-dimethylamino) naphthalene (PRODAN) revisited

    SciTech Connect

    Sun, S. |; Heitz, M.P.; Perez, S.A.; Colon, L.A.; Bruckenstein, S.; Bright, F.V.

    1997-09-01

    The photophysics of 6-propionyl-2-(N,N-dimethylamino) naphthalene (PRODAN) in liquid water are reported. Our results demonstrate that the often mentioned extra blue-edge shoulder seen for PRODAN in liquid water is a result of PRODAN-PRODAN intermolecular interactions in a supersaturated PRODAN solution and not a consequence of impurities in the commercial PRODAN preparations. In all cases where the aqueous PRODAN solution is not supersaturated, there is no detectable blue-edge emission shoulder. {copyright} {ital 1997} {ital Society for Applied Spectroscopy}

  11. [Morphological changes in gametes of tiger barb Puntius tetrazona (Cypriniformes: Cyprinidae) and the implementation of in vitro fertilization].

    PubMed

    Domínguez-Castanedo, Omar; Toledano-Olivares, Ángel; Martínez-Espinosa, David; Ávalos-Rodríguez, Alejandro

    2014-12-01

    The production of ornamental fishes represents an economic activity of a growing number of Mexican families. Nevertheless, the reproduction of fish in captivity is one of the complications faced by farmers. This study was set up to: (i) evaluate the morphological and functional changes induced by hydration in the gametes of fish tiger barb (Puntius tetrazona; 240 samples) at tree times after hydration (10, 20 and 30s) with classic spermograms (volume, sperm concentration, viability, motility, and normal morphology); and (ii) evaluate the implementation of in vitro fertilization based on the ovulation rate, the percentage of fertilization and hatching; and the larval numbers obtained after 72 hours. The average volume of milt was 3.0 ± 0.7 μL, and the minimum, maximum and average concentration of sperm was 44.4 x 10(6) spz/mL, 52.3 x 10(6) spz/mL, and 48.1 ± 5.9 x 10(6) spz/mL, respectively. The viability and motility of the sperm was 84.6 ± 3.2% and 81.5 ± 2.2%, respectively. The diameter of the sperm with/without water contact was 2.10 ± 6 μm and 3.8 ± 1.0 μm (p < 0.05); the largest diameter was recorded 30 seconds after the contact with water. For oocytes, the smaller and larger diameters were recorded at 10 and 30s, respectively (both with/without water contact); the oocytes diameters after 10 and 30 seconds of contact with water were 1.11 and 1.55 mm, respectively. A higher ovulation rate was recorded using the in vitro fertilization: 250 ± 50 oocytes versus 28 ± 09 oocytes (during natural fertilization; p < 0.05). Nevertheless, fertilization and hatching rates were higher for the natural fertilization (80 and 60%, respectively). Considering the number of larvae obtained after 72 hours, our results showed a higher value for the in vitro fertilization (75 ± 18 compared to 13.4 ± 12 of the natural fertilization; p < 0.05). We propose this fish as a model for other ornamental fishes of commercial interest. Our results demonstrate that the in vitro

  12. [Morphological changes in gametes of tiger barb Puntius tetrazona (Cypriniformes: Cyprinidae) and the implementation of in vitro fertilization].

    PubMed

    Domínguez-Castanedo, Omar; Toledano-Olivares, Ángel; Martínez-Espinosa, David; Ávalos-Rodríguez, Alejandro

    2014-12-01

    The production of ornamental fishes represents an economic activity of a growing number of Mexican families. Nevertheless, the reproduction of fish in captivity is one of the complications faced by farmers. This study was set up to: (i) evaluate the morphological and functional changes induced by hydration in the gametes of fish tiger barb (Puntius tetrazona; 240 samples) at tree times after hydration (10, 20 and 30s) with classic spermograms (volume, sperm concentration, viability, motility, and normal morphology); and (ii) evaluate the implementation of in vitro fertilization based on the ovulation rate, the percentage of fertilization and hatching; and the larval numbers obtained after 72 hours. The average volume of milt was 3.0 ± 0.7 μL, and the minimum, maximum and average concentration of sperm was 44.4 x 10(6) spz/mL, 52.3 x 10(6) spz/mL, and 48.1 ± 5.9 x 10(6) spz/mL, respectively. The viability and motility of the sperm was 84.6 ± 3.2% and 81.5 ± 2.2%, respectively. The diameter of the sperm with/without water contact was 2.10 ± 6 μm and 3.8 ± 1.0 μm (p < 0.05); the largest diameter was recorded 30 seconds after the contact with water. For oocytes, the smaller and larger diameters were recorded at 10 and 30s, respectively (both with/without water contact); the oocytes diameters after 10 and 30 seconds of contact with water were 1.11 and 1.55 mm, respectively. A higher ovulation rate was recorded using the in vitro fertilization: 250 ± 50 oocytes versus 28 ± 09 oocytes (during natural fertilization; p < 0.05). Nevertheless, fertilization and hatching rates were higher for the natural fertilization (80 and 60%, respectively). Considering the number of larvae obtained after 72 hours, our results showed a higher value for the in vitro fertilization (75 ± 18 compared to 13.4 ± 12 of the natural fertilization; p < 0.05). We propose this fish as a model for other ornamental fishes of commercial interest. Our results demonstrate that the in vitro

  13. The UV photochemistry of C2N2

    NASA Technical Reports Server (NTRS)

    Halpern, Joshua B.; Barts, Samuel A.

    1989-01-01

    The absorption, emission, and photodissociation yield spectra of C2N2 were measured in the 220 and 210 nm region near the 4(0)1 and 1(0)1 4(0)1 bands of the A 1 sigma + from the X 1 sigma + system. The emission spectrum showed very few lines which appeared in the absorption spectrum. Moreover, the emission had 660 ns lifetime and, at 210 nm a very large electronic emission quenching rate. Laser induced fluorescence was used to measure the relative yield of CN radicals as a function of photolysis wavelength. This spectrum seemed to follow the absorption spectrum below the dissociation threshold. Energy in the CN fragments appeared to be statistically distributed.

  14. Exact correlation functions in SU(2) N=2 superconformal QCD.

    PubMed

    Baggio, Marco; Niarchos, Vasilis; Papadodimas, Kyriakos

    2014-12-19

    We report an exact solution of 2- and 3-point functions of chiral primary fields in SU(2) N=2 super-Yang-Mills theory coupled to four hypermultiplets. It is shown that these correlation functions are nontrivial functions of the gauge coupling, obeying differential equations which take the form of the semi-infinite Toda chain. We solve these equations recursively in terms of the Zamolodchikov metric that can be determined exactly from supersymmetric localization on the four-sphere. Our results are verified independently in perturbation theory with a Feynman diagram computation up to 2 loops. This is a short version of a companion paper that contains detailed technical remarks, additional material, and aspects of an extension to the SU(N) gauge group. PMID:25554873

  15. Microtus oeconomus (Rodentia), a useful mammal for studying the induction of sex-chromosome nondisjunction and diploid gametes in male germ cells.

    PubMed Central

    Tates, A D

    1979-01-01

    Preliminary data indicate that chemicals can also increase the frequency of sex-chromosome nondisjunction. Positive results--which certainly need further confirmation--have been obtained for MMS, p-fluorophenylalanine, vincristine, procarbazine, carbendazim, and bleomycin. Nocodazole, benomyl, colcemic, 6-mercaptopurine, and halothane were all negative at the concentrations tested. For the induction of diploid spermatids positive results were only obtained for MMS and parafluorophenylalanine. In view of the results obtained, the Microtus system is considered a very useful tool for analyzing factors contributing to the high frequency of aneuploidy and triploidy among abortuses and of aneuploidy in liveborn infants of men. A method is described for the detection of sex-chromosome nondisjunction and diploid spermatids in male germ cells of the field vole Microtus oeconomus. The method is based on the unique distribution pattern of heterochromatin in Microtus cells, which makes it possible to identify X and Y chromosomes in early spermatids with a simple C-banding procedure. Slide preparation is easy. Scoring of early spermatids for extra sex-chromosomes is simple and 2000-4000 cells per hour can be examined. With the Microtus system it has now been demonstrated that radiation of spermatocyte stages with doses of 50, 100 and 200 R results in a higher frequency of sex chromosome nondisjunction and of diploid gametes. Both types of aberrant gametes can be produced during the first and second meiotic division. Images FIGURE 1. FIGURE 2. FIGURE 3. FIGURE 4. PMID:387396

  16. Influence of the duration of in vitro maturation and gamete co-incubation on the efficiency of in vitro embryo development in Italian Mediterranean buffalo (Bubalus bubalis).

    PubMed

    Gasparrini, Bianca; De Rosa, Anna; Attanasio, Laura; Boccia, Lucia; Di Palo, Rossella; Campanile, Giuseppe; Zicarelli, Luigi

    2008-05-01

    The aim of this study was to investigate the effect of the duration of oocyte in vitro maturation (IVM) and gamete co-incubation on the in vitro embryo (IVEP) production efficiency in River buffalo. In Experiment 1, abattoir-derived cumulus oocyte complexes were fixed at 0, 3, 6, 9, 12, 15, 18, 21 and 24 h after the start of in vitro maturation to study the kinetics of nuclear maturation. In Experiment 2, cumulus oocyte complexes were fertilized in vitro following in vitro maturation for 18, 21, 24, 27 or 30 h. After 20 h of gamete co-incubation, presumptive zygotes were denuded and cultured in vitro in synthetic oviduct fluid (SOF) medium. In Experiment 3, following in vitro maturation and fertilization, presumptive zygotes were removed from fertilization drops at 8, 12, 16 and 20 h post-insemination (pi) and placed in culture as described above. Representative samples of oocytes were fixed at 4, 8, 12, 16 and 20 h to evaluate the sperm penetration rate and the incidence of polyspermy at different co-incubation times. The main conclusions of the study are that: (1) the majority of buffalo oocytes accomplish nuclear maturation between 21 and 24 h after the start of in vitro maturation; (2) both cleavage and blastocyst rates linearly decrease with increasing duration of in vitro maturation (from 18 to 30 h); (3) sperm-oocyte incubation for at least 16 h is required for maximum blastocyst yields. PMID:17481834

  17. Extreme geographical fixation of variation in the Plasmodium falciparum gamete surface protein gene Pfs48/45 compared with microsatellite loci.

    PubMed

    Conway, D J; Machado, R L; Singh, B; Dessert, P; Mikes, Z S; Povoa, M M; Oduola, A M; Roper, C

    2001-07-01

    Comparing patterns of genetic variation at multiple loci in the genome of a species can potentially identify loci which are under selection. The large number of polymorphic microsatellites in the malaria parasite Plasmodium falciparum are available markers to screen for selectively important loci. The Pfs48/45 gene on Chromosome 13 encodes an antigenic protein located on the surface of parasite gametes, which is a candidate for a transmission blocking vaccine. Here, genotypic data from 255 P. falciparum isolates are presented, which show that alleles and haplotypes of five single nucleotide polymorphisms (SNPs) in the Pfs48/45 gene are exceptionally skewed in frequency among different P. falciparum populations, compared with alleles at 11 microsatellite loci sampled widely from the parasite genome. Fixation indices measuring inter-population variance in allele frequencies (F(ST)) were in the order of four to seven times higher for Pfs48/45 than for the microsatellites, whether considered (i) among populations within Africa, or (ii) among different continents. Differing mutational processes at microsatellite and SNP loci could generally affect the population structure at these different types of loci, to an unknown extent which deserves further investigation. The highly contrasting population structure may also suggest divergent selection on the amino acid sequence of Pfs48/45 in different populations, which plausibly indicates a role for the protein in determining gamete recognition and compatibility. PMID:11420101

  18. Polyploid formation pathways have an impact on genetic rearrangements in resynthesized Brassica napus.

    PubMed

    Szadkowski, E; Eber, F; Huteau, V; Lodé, M; Coriton, O; Jenczewski, E; Chèvre, A M

    2011-08-01

    • Polyploids can be produced by the union of unreduced gametes or through somatic doubling of F(1) interspecific hybrids. The first route is suspected to produce allopolyploid species under natural conditions, whereas experimental data have only been thoroughly gathered for the latter. • We analyzed the meiotic behavior of an F(1) interspecific hybrid (by crossing Brassica oleracea and B.rapa, progenitors of B.napus) and the extent to which recombined homoeologous chromosomes were transmitted to its progeny. These results were then compared with results obtained for a plant generated by somatic doubling of this F₁ hybrid (CD.S₀) and an amphidiploid (UG.S₀) formed via a pathway involving unreduced gametes; we studied the impact of this method of polyploid formation on subsequent generations. • This study revealed that meiosis of the F₁ interspecific hybrid generated more gametes with recombined chromosomes than did meiosis of the plant produced by somatic doubling, although the size of these translocations was smaller. In the progeny of the UG.S₀ plant, there was an unexpected increase in the frequency at which the C1 chromosome was replaced by the A1 chromosome. • We conclude that polyploid formation pathways differ in their genetic outcome. Our study opens up perspectives for the understanding of polyploid origins.

  19. Neutron capture and (n,2n) measurements on 241Am

    SciTech Connect

    Vieira, D; Jandel, M; Bredeweg, T; Bond, E; Clement, R; Couture, A; Haight, R; O'Donnell, J; Reifarth, R; Ullmann, J; Wilhelmy, J; Wouters, J; Tonchev, A; Hutcheson, A; Angell, C; Crowell, A; Fallin, B; Hammond, S; Howell, C; Karowowski, H; Kelley, J; Pedroni, R; Tornow, W; Macri, R; Agvaanluvsan, U; Becker, J; Dashdorj, D; Stoyer, M; Wu, C

    2007-07-18

    We report on a set of neutron-induced reaction measurements on {sup 241}Am which are important for nuclear forensics and advanced nuclear reactor design. Neutron capture measurements have been performed on the DANCE detector array at the Los Alamos Neutron Scattering CEnter (LANSCE). In general, good agreement is found with the most recent data evaluations up to an incident neutron energy of {approx} 300 keV where background limits the measurement. Using mono-energetic neutrons produced in the {sup 2}H(d,n){sup 3}He reaction at Triangle University Nuclear Laboratory (TUNL), we have measured the {sup 241}Am(n,2n) excitation function from threshold (6.7 MeV) to 14.5 MeV using the activation method. Good agreement is found with previous measurements, with the exception of the three data points reported by Perdikakis et al. around 11 MeV, where we obtain a much lower cross section that is more consistent with theoretical estimates.

  20. A blackbody-pumped CO2-N2 transfer laser

    NASA Astrophysics Data System (ADS)

    Deyoung, R. J.; Higdon, N. S.

    1984-08-01

    A compact blackbody-pumped CO2-N2 transfer laser was constructed and the significant operating parameters were investigated. Lasing was achieved at 10.6 microns by passing preheated N2 through a 1.5-mm-diameter nozzle to a laser cavity where the N2 was mixed with CO2 and He. An intrinsic efficiency of 0.7 percent was achieved for an oven temperature of 1473 K and N2 oven pressure of 440 torr. The optimum laser cavity consisted of a back mirror with maximum reflectivity and an output mirror with 97.5-percent reflectivity. The optimum gas mixture was 1CO2/.5He/6N2. The variation of laser output was measured as a function of oven temperature, nozzle diameter, N2 oven pressure, He and CO2 partial pressures, nozzle-to-oven separation, laser cell temperature, and output laser mirror reflectivity. With these parameters optimized, outputs approaching 1.4 watts were achieved.

  1. Etch Properties of Amorphous Carbon Material Using RF Pulsing in the O2/N2/CHF3 Plasma.

    PubMed

    Jeon, Min Hwan; Park, Jin Woo; Yun, Deok Hyun; Kim, Kyong Nam; Yeom, Geun Young

    2015-11-01

    The amorphous carbon layer (ACL), used as the hardmask for the etching of nanoscale semi-conductor materials, was etched using O2/CHF3 in addition to O2/N2 using pulsed dual-frequency capacitively coupled plasmas, and the effects of source power pulsing for different gas combinations on the characteristics of the plasmas and ACL etching were investigated. As the etch mask for ACL, a patterned SiON layer was used. The etch rates of ACL were decreased with the decrease of pulse duty percentage for both O2/N2 and O2/CHF3 due to decrease of the reactive radicals, such as F and O, with decreasing pulse duty percentage. In addition, at the same pulse duty percentage, the etch selectivity of ACL/SiON with O2/CHF3 was also significantly lower than that with O2/N2. However, the etch profiles of ACL with O2/CHF3 was more anisotropic and the etch profiles were further improved with decreasing the pulse duty percentage than those of ACL with O2/N2. The improved anisotropic etch profiles of ACL with decreasing pulse duty percentage for O2/CHF3 were believed to be related to the formation of a more effective passivation layer, such as a thick fluorocarbon layer, on the sidewall of the ACL during the etching with O2/CHF3, compared to the weak C-N passivation layer formed on the sidewall of ACL when using O2/N2. PMID:26726555

  2. A note on four-particle form factors of operators {T}_{2n}{T}_{-2n} in the sinh-Gordon model

    NASA Astrophysics Data System (ADS)

    Lashkevich, Michael; Pugai, Yaroslav

    2016-07-01

    The diagonal matrix elements < {θ }1,{θ }2| {T}2n{T}-2n| {θ }1,{θ }2> between two-particle states in the sinh-Gordon model are computed analytically for all integers n\\gt 0. This confirms the proposal [1] by Smirnov and Zamolodchikov for these matrix elements and demonstrates the effectiveness of the algebraic approach to form factors.

  3. Two HAP2-GCS1 homologs responsible for gamete interactions in the cellular slime mold with multiple mating types: Implication for common mechanisms of sexual reproduction shared by plants and protozoa and for male-female differentiation.

    PubMed

    Okamoto, Marina; Yamada, Lixy; Fujisaki, Yukie; Bloomfield, Gareth; Yoshida, Kentaro; Kuwayama, Hidekazu; Sawada, Hitoshi; Mori, Toshiyuki; Urushihara, Hideko

    2016-07-01

    Fertilization is a central event in sexual reproduction, and understanding its molecular mechanisms has both basic and applicative biological importance. Recent studies have uncovered the molecules that mediate this process in a variety of organisms, making it intriguing to consider conservation and evolution of the mechanisms of sexual reproduction across phyla. The social amoeba Dictyostelium discoideum undergoes sexual maturation and forms gametes under dark and humid conditions. It exhibits three mating types, type-I, -II, and -III, for the heterothallic mating system. Based on proteome analyses of the gamete membranes, we detected expression of two homologs of the plant fertilization protein HAP2-GCS1. When their coding genes were disrupted in type-I and type-II strains, sexual potency was completely lost, whereas disruption in the type-III strain did not affect mating behavior, suggesting that the latter acts as female in complex organisms. Our results demonstrate the highly conserved function of HAP2-GCS1 in gamete interactions and suggest the presence of additional allo-recognition mechanisms in D. discoideum gametes.

  4. Two HAP2-GCS1 homologs responsible for gamete interactions in the cellular slime mold with multiple mating types: Implication for common mechanisms of sexual reproduction shared by plants and protozoa and for male-female differentiation.

    PubMed

    Okamoto, Marina; Yamada, Lixy; Fujisaki, Yukie; Bloomfield, Gareth; Yoshida, Kentaro; Kuwayama, Hidekazu; Sawada, Hitoshi; Mori, Toshiyuki; Urushihara, Hideko

    2016-07-01

    Fertilization is a central event in sexual reproduction, and understanding its molecular mechanisms has both basic and applicative biological importance. Recent studies have uncovered the molecules that mediate this process in a variety of organisms, making it intriguing to consider conservation and evolution of the mechanisms of sexual reproduction across phyla. The social amoeba Dictyostelium discoideum undergoes sexual maturation and forms gametes under dark and humid conditions. It exhibits three mating types, type-I, -II, and -III, for the heterothallic mating system. Based on proteome analyses of the gamete membranes, we detected expression of two homologs of the plant fertilization protein HAP2-GCS1. When their coding genes were disrupted in type-I and type-II strains, sexual potency was completely lost, whereas disruption in the type-III strain did not affect mating behavior, suggesting that the latter acts as female in complex organisms. Our results demonstrate the highly conserved function of HAP2-GCS1 in gamete interactions and suggest the presence of additional allo-recognition mechanisms in D. discoideum gametes. PMID:27189178

  5. Impaired gamete production and viability in Atlantic croaker collected throughout the 20,000 km(2) hypoxic region in the northern Gulf of Mexico.

    PubMed

    Thomas, Peter; Rahman, Md Saydur; Picha, Matthew E; Tan, Wenxian

    2015-12-15

    The long-term impacts of recent marked increases in the incidence and extent of hypoxia (dissolved oxygen <2 mg/L) in coastal regions worldwide on fisheries and ecosystems are unknown. Reproductive impairment was investigated in Atlantic croaker collected in 2010 from the extensive coastal hypoxic region in the northern Gulf of Mexico. Potential fecundity was significantly lower in croaker collected throughout the ~20,000 km(2) hypoxic region than in croaker from normoxic sites. In vitro bioassays of gamete viability showed reductions in oocyte maturation and sperm motility in croaker collected from the hypoxic sites in response to reproductive hormones which were accompanied by decreases in gonadal levels of membrane progestin receptor alpha, the receptor regulating these processes. The finding that environmental hypoxia exposure reduces oocyte viability in addition to decreasing oocyte production in croaker suggests that fecundity estimates need to be adjusted to account for the decrease in oocyte maturation.

  6. Bingel-Hirsch addition on non-isolated-pentagon-rule Gd3N@C2n (2n = 82 and 84) metallofullerenes: products under kinetic control.

    PubMed

    Alegret, Núria; Salvadó, Patricia; Rodríguez-Fortea, Antonio; Poblet, Josep M

    2013-10-01

    Bingel-Hirsch reactions on fullerenes take place under kinetic control. We here predict, by means of DFT methodology, the products of the Bingel-Hirsch addition on non-isolated-pentagon-rule (non-IPR) metallofullerenes Gd3N@C2n (2n = 82, 84), as modeled by closed-shell Y3N@C2n systems. Adducts on [6,6] B-type bonds placed near the pentalene unit are predicted for the two cages, as found for other non-IPR endohedral fullerenes such as Sc3N@C68.

  7. IR and electrochemical synthesis and characterization of thin films of PEDOT grown on platinum single crystal electrodes in [EMMIM]Tf2N ionic liquid.

    PubMed

    Sandoval, Andrea P; Suárez-Herrera, Marco F; Feliu, Juan M

    2015-01-01

    Thin films of PEDOT synthesized on platinum single electrodes in contact with the ionic liquid 1-ethyl-2,3-dimethylimidazolium triflimide ([EMMIM]Tf2N) were studied by cyclic voltammetry, chronoamperometry, infrared spectroscopy and atomic force microscopy. It was found that the polymer grows faster on Pt(111) than on Pt(110) or Pt(100) and that the redox reactions associated with the PEDOT p-doping process are much more reversible in [EMMIM]Tf2N than in acetonitrile. Finally, the ion exchange and charge carriers' formation during the p-doping reaction of PEDOT were studied using in situ FTIR spectroscopy. PMID:25815089

  8. IR and electrochemical synthesis and characterization of thin films of PEDOT grown on platinum single crystal electrodes in [EMMIM]Tf2N ionic liquid

    PubMed Central

    Sandoval, Andrea P; Suárez-Herrera, Marco F

    2015-01-01

    Summary Thin films of PEDOT synthesized on platinum single electrodes in contact with the ionic liquid 1-ethyl-2,3-dimethylimidazolium triflimide ([EMMIM]Tf2N) were studied by cyclic voltammetry, chronoamperometry, infrared spectroscopy and atomic force microscopy. It was found that the polymer grows faster on Pt(111) than on Pt(110) or Pt(100) and that the redox reactions associated with the PEDOT p-doping process are much more reversible in [EMMIM]Tf2N than in acetonitrile. Finally, the ion exchange and charge carriers’ formation during the p-doping reaction of PEDOT were studied using in situ FTIR spectroscopy. PMID:25815089

  9. The persistent and pernicious myth of the early CO2-N2 atmospheres of terrestrial planets

    NASA Astrophysics Data System (ADS)

    Shaw, G. H.

    2009-12-01

    The accepted model for early atmospheres of terrestrial planets has settled on a CO2-N2 composition. Unfortunately, while it is largely based on a brilliant geological analysis by Rubey, there is no compelling evidence whatsoever for such a composition as the first “permanent” atmosphere for Earth or any other planet. In fact, geological discoveries of the past 50+ years reveal several problems with a CO2-N2 atmosphere, some of which Rubey recognized in his own analysis. He clearly addressed the problem of timing of degassing, concluding that early massive degassing of CO2 would produce readily observed and profound effects, which are not evident. Modeling and constraints on the timing of planetary accretion and core formation indicate massive early degassing. If early degassing emitted CO2-N2, the effects are concealed. Plate tectonic recycling is not a solution, as conditions would have persisted beyond the time of the earliest rocks, which do not show the effects. Attempts to return degassed CO2 to the mantle are not only ad hoc, but inconsistent with early thermal structure of the Earth. Second, production of prebiotic organic compounds from a CO2-N2 atmosphere has been a nagging problem. At best this has been addressed by invoking hydrogen production from the mantle to provide reducing capacity. While hydrogen may be emitted in volcanic eruptions, it is exceedingly difficult to imagine this process generating enough organics to yield high concentrations in a global ocean. The recent fashion of invoking organic synthesis at deep-sea vents suffers from the same problem: how to achieve sufficient concentrations of organics in a global ocean by abiotic synthesis when hydrothermal activity stirs the solution and carries the prebiotic products off to great dilution? Suggesting life began at deep-sea vents, and continues to carry on chemosynthesis there, begs the question. Unless you get high enough concentrations of prebiotics by abiotic processes, you simply

  10. Incorporation of Pendant Bases into Rh(diphosphine)2 Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO2 Hydrogenation Activity of [Rh(P2N2)2](+) Complexes.

    PubMed

    Lilio, Alyssia M; Reineke, Mark H; Moore, Curtis E; Rheingold, Arnold L; Takase, Michael K; Kubiak, Clifford P

    2015-07-01

    A series of five [Rh(P2N2)2](+) complexes (P2N2 = 1,5-diaza-3,7-diphosphacyclooctane) have been synthesized and characterized: [Rh(P(Ph)2N(Ph)2)2](+) (1), [Rh(P(Ph)2N(Bn)2)2](+) (2), [Rh(P(Ph)2N(PhOMe)2)2](+) (3), [Rh(P(Cy)2N(Ph)2)2](+) (4), and [Rh(P(Cy)2N(PhOMe)2)2](+) (5). Complexes 1-5 have been structurally characterized as square planar rhodium bis-diphosphine complexes with slight tetrahedral distortions. The corresponding hydride complexes 6-10 have also been synthesized and characterized, and X-ray diffraction studies of HRh(P(Ph)2N(Bn)2)2 (7), HRh(P(Ph)2N(PhOMe)2)2 (8) and HRh(P(Cy)2N(Ph)2)2 (9) show that the hydrides have distorted trigonal bipyramidal geometries. Equilibration of complexes 2-5 with H2 in the presence of 2,8,9-triisopropyl-2,5,8,9-tetraaza-1-phosphabicyclo[3,3,3]undecane (Verkade's base) enabled the determination of the hydricities and estimated pKa's of the Rh(I) hydride complexes using the appropriate thermodynamic cycles. Complexes 1-5 were active for CO2 hydrogenation under mild conditions, and their relative rates were compared to that of [Rh(depe)2](+), a nonpendant-amine-containing complex with a similar hydricity to the [Rh(P2N2)2](+) complexes. It was determined that the added steric bulk of the amine groups on the P2N2 ligands hinders catalysis and that [Rh(depe)2](+) was the most active catalyst for hydrogenation of CO2 to formate. PMID:26042557

  11. All-optical code-division multiple-access applications: 2(n) extended-prime codes.

    PubMed

    Zhang, J G; Kwong, W C; Mann, S

    1997-09-10

    A new family of 2(n) codes, called 2(n) extended-prime codes, is proposed for all-optical code-division multiple-access networks. Such 2(n) codes are derived from so-called extended-prime codes so that their cross-correlation functions are not greater than 1, as opposed to 2 for recently proposed 2(n) prime codes. As a result, a larger number of active users can now be supported by the new codes for a given bit-error rate than can be by 2(n) prime codes, while power-efficient, waveguide-integrable all-serial coding and correlating configurations proposed for the 2(n) prime codes can still be employed.

  12. Ortho-to-Para Ratio in Interstellar Water on the Sightline toward Sagittarius B2(N)

    NASA Astrophysics Data System (ADS)

    Lis, Dariusz C.; Bergin, Edwin A.; Schilke, Peter; van Dishoeck, Ewine F.

    2013-10-01

    The determination of the water ortho-to-para ratio (OPR) is of great interest for studies of the formation and thermal history of water ices in the interstellar medium and protoplanetary disk environments. We present new Herschel observations of the fundamental rotational transitions of ortho- and para-water on the sightline toward Sagittarius B2(N), which allow improved estimates of the measurement uncertainties due to instrumental effects and assumptions about the excitation of water molecules. These new measurements, suggesting a spin temperature of 24-32 K, confirm the earlier findings of an OPR below the high-temperature value on the nearby sightline toward Sagittarius B2(M). The exact implications of the low OPR in the galactic center molecular gas remain unclear and will greatly benefit from future laboratory measurements involving water freeze-out and evaporation processes under low-temperature conditions, similar to those present in the galactic interstellar medium. Given the specific conditions in the central region of the Milky Way, akin to those encountered in active Galactic nuclei, gas-phase processes under the influence of strong X-ray and cosmic ray ionization also have to be carefully considered. We summarize some of the latest laboratory measurements and their implications here.

  13. High pressure stability of hydrazine (H2N-NH2) : Implications for energetic hydronitrogen compounds

    NASA Astrophysics Data System (ADS)

    Chellappa, Raja; Dattelbaum, Dana; Liu, Zhenxian

    2013-06-01

    Hydrazine (H2N-NH2) is a metastable, high energy density molecule that is relevant to planetary physics and plays an important role in industrial synthesis and propellant applications. Theoretical calculations have predicted the existence of ``hydronitrogen'' extended solids that hold great potential as a high energy density material (HEDM). Exploring the high pressure-temperature (P - T) stability of hydrazine will provide crucial insights into hydrogen bonded -N-H networks under these conditions. Further, related simple molecules such as CH4, NH3, CO, and CO2 have been shown to have rich high P - T phase diagrams, often forming extended amorphous solids. Here, we report the first comprehensive study of hydrazine to 50 GPa at ambient temperature, using both in situ vibrational spectroscopy and synchrotron x-ray diffraction to elucidate structural changes driven by compression. Liquid hydrazine solidifies into a monoclinic structure at 0.5 GPa that is isomorphous with the low- T solid phase. Further compression drives structural re-ordering and at least 2 phase transformations to 20 GPa, with complex anisotropic hydrogen bonding interactions. Surprisingly, no evidence for the formation of extended amorphous solids was observed to the highest pressure studied.

  14. Numerical simulations of turbulent premixed H2/O2/N2 flames with complex chemistry

    NASA Technical Reports Server (NTRS)

    Baum, M.; Poinsot, T. J.; Haworth, D. C.

    1992-01-01

    Premixed stoichiometric H2/O2/N2 flames propagating in two-dimensional turbulence were studied using direct numerical simulation (simulations in which all fluid and thermochemical scales are fully resolved) including realistic chemical kinetics and molecular transport. Results are compared with earlier zero-chemistry (flame sheet) and one-step chemistry simulations. Consistent with the simpler models, the turbulent flame with realistic chemistry aligns preferentially with extensive strain rates in the tangent plane and flame curvature probability density functions are close to symmetric with near-zero means. By contrast to simple-chemistry results with non-unity Lewis numbers (ratio of thermal to species diffusivity), local flame structure does not correlate with curvature but rather with tangential strain rate. Turbulent straining results in substantial thinning of the flame relative to the steady unstrained laminar case. Heat release and H2O2 contours remain thin and connected ('flamelet-like') while species including H-atom and OH are more diffuse. Peak OH concentration occurs well behind the peak heat-release zone. The feasibility of incorporating realistic chemistry into full turbulence simulations to address issues such as pollutant formation in hydrocarbon-air flames is suggested.

  15. Ortho-to-para ratio in interstellar water on the sightline toward Sagittarius B2(N).

    PubMed

    Lis, Dariusz C; Bergin, Edwin A; Schilke, Peter; van Dishoeck, Ewine F

    2013-10-01

    The determination of the water ortho-to-para ratio (OPR) is of great interest for studies of the formation and thermal history of water ices in the interstellar medium and protoplanetary disk environments. We present new Herschel observations of the fundamental rotational transitions of ortho- and para-water on the sightline toward Sagittarius B2(N), which allow improved estimates of the measurement uncertainties due to instrumental effects and assumptions about the excitation of water molecules. These new measurements, suggesting a spin temperature of 24-32 K, confirm the earlier findings of an OPR below the high-temperature value on the nearby sightline toward Sagittarius B2(M). The exact implications of the low OPR in the galactic center molecular gas remain unclear and will greatly benefit from future laboratory measurements involving water freeze-out and evaporation processes under low-temperature conditions, similar to those present in the galactic interstellar medium. Given the specific conditions in the central region of the Milky Way, akin to those encountered in active Galactic nuclei, gas-phase processes under the influence of strong X-ray and cosmic ray ionization also have to be carefully considered. We summarize some of the latest laboratory measurements and their implications here. PMID:23656468

  16. Structure of the Tuberous Sclerosis Complex 2 (TSC2) N Terminus Provides Insight into Complex Assembly and Tuberous Sclerosis Pathogenesis.

    PubMed

    Zech, Reinhard; Kiontke, Stephan; Mueller, Uwe; Oeckinghaus, Andrea; Kümmel, Daniel

    2016-09-16

    Tuberous sclerosis complex (TSC) is caused by mutations in the TSC1 and TSC2 tumor suppressor genes. The gene products hamartin and tuberin form the TSC complex that acts as GTPase-activating protein for Rheb and negatively regulates the mammalian target of rapamycin complex 1 (mTORC1). Tuberin contains a RapGAP homology domain responsible for inactivation of Rheb, but functions of other protein domains remain elusive. Here we show that the TSC2 N terminus interacts with the TSC1 C terminus to mediate complex formation. The structure of the TSC2 N-terminal domain from Chaetomium thermophilum and a homology model of the human tuberin N terminus are presented. We characterize the molecular requirements for TSC1-TSC2 interactions and analyze pathological point mutations in tuberin. Many mutations are structural and produce improperly folded protein, explaining their effect in pathology, but we identify one point mutant that abrogates complex formation without affecting protein structure. We provide the first structural information on TSC2/tuberin with novel insight into the molecular function.

  17. Galaxy formation with radiative and chemical feedback

    NASA Astrophysics Data System (ADS)

    Graziani, L.; Salvadori, S.; Schneider, R.; Kawata, D.; de Bennassuti, M.; Maselli, A.

    2015-05-01

    Here we introduce GAMESH, a novel pipeline that implements self-consistent radiative and chemical feedback in a computational model of galaxy formation. By combining the cosmological chemical-evolution model GAMETE with the radiative transfer code CRASH, GAMESH can post-process realistic outputs of a N-body simulation describing the red-shift evolution of the forming galaxy. After introducing the GAMESH implementation and its features, we apply the code to a low-resolution N-body simulation of the formation of the Milky Way and we investigate the combined effects of self-consistent radiative and chemical feedback. Many physical properties, which can be directly compared with observations in the Galaxy and its surrounding satellites, are predicted by the code along with the merger-tree assembly. The resulting red-shift evolution for the Local Group of star-formation rates, reionization and metal enrichment along with the predicted metallicity distribution function of halo stars are critically compared with observations. We discuss the merits and limitations of the first release of GAMESH, which also opens new directions to a full implementation of feedback processes in galaxy-formation models by combining semi-analytic and numerical methods.

  18. The bis metallacyclic anion [U(N{SiMe3}2)(CH2SiMe2N{SiMe3})2]-.

    PubMed

    Bénaud, Olivier; Berthet, Jean-Claude; Thuéry, Pierre; Ephritikhine, Michel

    2010-09-01

    A series of bis metallacyclic compounds [M(THF)(x)UN*(CH(2)SiMe(2)N{SiMe(3)})(2)](n) [M = Na (2), Li (3), or K (4), N* = N(SiMe(3))(2)] were isolated from reactions of UCl(4) or [UN*(3)Cl] with MN* or by treatment of [UN*(2)(CH(2)SiMe(2)N{SiMe(3)})] (1) or [UN*(3)] with MN*, MH, or LiCH(2)SiMe(3) in tetrahydrofuran (THF). Crystals of 2a x 1/6n-pentane (x = 0), 2b (x = 1), 2c (x = 2), and 4b (x = 1) were obtained by crystallization of 2 and 4 from pentane, and [Na(18-crown-6)(THF)][UN*(CH(2)SiMe(2)N{SiMe(3)})(2)] (2d) and [Na(15-crown-5)][UN*(CH(2)SiMe(2)N{SiMe(3)})(2)] (2e) were formed upon addition of the crown ether. The crystal structures of 2a-2e and 4b exhibit the same [UN*(CH(2)SiMe(2)N{SiMe(3)})(2)] units which are linked to Na or K atoms via methylene or methyl groups, giving either tight cation-anion pairs (2d and 2e) or one-dimensional (1D) or two-dimensional (2D) polymeric compounds with Na or K atoms in bridging position between methylene groups of adjacent units. Reaction of 2 with CO gave the double insertion derivative [Na(2)(THF)U(2)N*(2)(OC{=CH(2)}SiMe(2)N{SiMe(3)})(4)] (5b) and [Na(15-crown-5)UN*(OC{=CH(2)}SiMe(2)N{SiMe(3)})(2)] (5c) in the presence of the crown ether. Thermal decomposition of 5b gave [Na(2)(THF)U(OC{=CH(2)}SiMe(2)N{SiMe(3)})(3)](2) (6), the product of CO insertion into the putative tris metallacycle [Na(2)(THF)(x)U(CH(2)SiMe(2)N{SiMe(3)})(3)]. The crystal structures of 5b, 5c, and 6 show the interaction of the Na atoms with the exocyclic C=CH(2) bonds. Diffusion of CO(2) into a THF solution of 2 led to the formation of [Na(THF)(x)UN*(OC{O}CH(2)SiMe(2)N{SiMe(3)})(2)] (7) which crystallized from pyridine/pentane to give [Na(THF)(2)(py)(2)UN*(OC{O}CH(2)SiMe(2)N{SiMe(3)})(2)] x 0.5 py (8 x 0.5 py), the first crystallographically characterized complex resulting from CO(2) insertion into a M(CH(2)SiMe(2)N{SiMe(3)}) metallacycle. Compound 2 reacted with I(2) to give [UN*(CH(2)SiMe(2)N{SiMe(3)})(N{SiMe(3)}SiMe(2)CH(2)I)] (9) which would

  19. Systematics of (n,2n) and (n,3n) Cross Sections.

    1991-10-08

    Version 00 SC2N3N can be used to calculate the (n2n) and (n3n) cross section in the energy region from threshold to about 25 MeV with the systematics parameters which well reproduce the experiment in the mass region of 23.le.A.le.238 (especially between 45 and 197.)

  20. Homeostatic regulation of meiotic DSB formation by ATM/ATR

    SciTech Connect

    Cooper, Tim J.; Wardell, Kayleigh; Garcia, Valerie; Neale, Matthew J.

    2014-11-15

    Ataxia–telangiectasia mutated (ATM) and RAD3-related (ATR) are widely known as being central players in the mitotic DNA damage response (DDR), mounting responses to DNA double-strand breaks (DSBs) and single-stranded DNA (ssDNA) respectively. The DDR signalling cascade couples cell cycle control to damage-sensing and repair processes in order to prevent untimely cell cycle progression while damage still persists [1]. Both ATM/ATR are, however, also emerging as essential factors in the process of meiosis; a specialised cell cycle programme responsible for the formation of haploid gametes via two sequential nuclear divisions. Central to achieving accurate meiotic chromosome segregation is the introduction of numerous DSBs spread across the genome by the evolutionarily conserved enzyme, Spo11. This review seeks to explore and address how cells utilise ATM/ATR pathways to regulate Spo11-DSB formation, establish DSB homeostasis and ensure meiosis is completed unperturbed.

  1. Ab initio study of neutral (TiO2)n clusters and their interactions with water and transition metal atoms.

    PubMed

    Cakır, D; Gülseren, O

    2012-08-01

    We have systematically investigated the growth behavior and stability of small stoichiometric (TiO(2))(n) (n = 1-10) clusters as well as their structural, electronic and magnetic properties by using the first-principles plane wave pseudopotential method within density functional theory. In order to find out the ground state geometries, a large number of initial cluster structures for each n has been searched via total energy calculations. Generally, the ground state structures for the case of n = 1-9 clusters have at least one monovalent O atom, which only binds to a single Ti atom. However, the most stable structure of the n = 10 cluster does not have any monovalent O atom. On the other hand, Ti atoms are at least fourfold coordinated for the ground state structures for n ≥ 4 clusters. Our calculations have revealed that clusters prefer to form three-dimensional structures. Furthermore, all these stoichiometric clusters have nonmagnetic ground state. The formation energy and the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap for the most stable structure of (TiO(2))(n) clusters for each n have also been calculated. The formation energy and hence the stability increases as the cluster size grows. In addition, the interactions between the ground state structure of the (TiO(2))(n) cluster and a single water molecule have been studied. The binding energy (E(b)) of the H(2)O molecule exhibits an oscillatory behavior with the size of the clusters. A single water molecule preferably binds to the cluster Ti atom through its oxygen atom, resulting an average binding energy of 1.1 eV. We have also reported the interaction of the selected clusters (n = 3, 4, 10) with multiple water molecules. We have found that additional water molecules lead to a decrease in the binding energy of these molecules to the (TiO(2))(n) clusters. Finally, the adsorption of transition metal (TM) atoms (V, Co and Pt) on the n = 10 cluster has been

  2. An 18-month survey of infertility treatment by in vitro fertilization, gamete and zygote intrafallopian transfer, and replacement of frozen-thawed embryos.

    PubMed

    Staessen, C; Camus, M; Khan, I; Smitz, J; Van Waesberghe, L; Wisanto, A; Devroey, P; Van Steirteghem, A C

    1989-02-01

    An 18-month survey of infertility treatment by in vitro fertilization (IVF) and related procedures at the Centre for Reproductive Medicine of the Vrije Universiteit Brussel is described. During this period, 1326 treatment cycles were started in patients with long-standing infertility and 1135 oocyte retrievals were performed in 771 different patients. IVF and embryo transfer (ET) after laparoscopic (N = 793) or ultrasonically guided (N = 342) ovum pickup, gamete intrafallopian transfer (GIFT; N = 284), or zygote intrafallopian transfer (ZIFT; N = 15) combined with IVF as well as the replacement of cryopreserved embryos yielded an overall pregnancy rate of 21.8% per started cycle. Echographic and laparoscopic oocyte retrieval gave similar results except for a higher fertilization rate after echographic-guided retrieval. For in vitro fertilization and embryo transfer an overall pregnancy rate of 26% per transfer was obtained. For GIFT and ZIFT the pregnancy rates were, respectively, 27.8 and 46.7% per replacement. For each procedure one-third of the pregnancies aborted. After the replacement of frozen and thawed embryos, during a natural cycle, a significantly lower fetal loss was observed.

  3. The role of gametes of the macroalgae Ascophyllum nodosum (L.) Le Jolis and Fucus vesiculosus L. (Fucales, Phaeophyceae) in summer nanoplankton of the White Sea coastal waters

    NASA Astrophysics Data System (ADS)

    Maximova, O. V.; Sazhin, A. F.

    2010-04-01

    Studies of macrophytes in the coastal zone of the Artic Seas, including the White Sea, have shown the essential role of these algae in the activity of the coastal half-latitude ecosystems. In summer, during the macrophyte reproduction period, a great number of reproduction products are released into the water. For a short time, this considerably affects the ratio of the nanoplankton in the populations that inhibit the vast and shallow coastal areas. At different coastal sites in Chernorechenskaya Inlet, Kadalaksha Bay, during the period of intensive reproduction of Ascophyllum nodosum and Fucus vesiculosus, 42 plankton samples were collected in 2005. During this period the concentration of antherozoids in the water reached 55000 cells/ml (216 mg C/m3). The number of eggs was within the range of 0.05-0.7 cells/ml. The proportion of antherozoids in the total biomass of nanoplankton varied at different coastal sites from 0.37 to 99%, with a mean of 46% for the reproduction period of A. nodosum, and only 7% for the reproduction period of F. vesiculosus. As was shown by counts of F. vesiculosus female gametes in sedimentation traps, 1 m2 of the macrophyte bed (assuming 100% coverage) produces 18000-108000 eggs per day (0.33-2 mg C). The calculated flux of the reproductive material from the brown algae beds to the coastal water shows good agreement with the sample counts.

  4. The consequences of S.H. and Others v. Austria for legislation on gamete donation in Europe: an ethical analysis of the European Court of Human Rights judgments.

    PubMed

    Van Hoof, Wannes; Pennings, Guido

    2012-12-01

    There is a high degree of legal diversity within Europe concerning medically assisted reproduction. This is in direct opposition to the project of harmonization of the European institutions. This paper takes a closer look at the different national interpretations of the European Convention on Human Rights with regard to gamete donation. In the case of S.H. and Others v. Austria, the European Court of Human Rights originally condemned the prohibitions on egg donation and sperm donation for the purpose of IVF. The court judged the law to be incoherent and disproportionate. This decision was recently reversed on appeal based on the margin of appreciation doctrine. This paper critically reviews the judgments of the European Court of Human Rights and analyses what this case means for the future of legislation on medically assisted reproduction in Europe. It is concluded that legal diversity and cross-border reproductive care will persist and that the court failed to protect European patients from arbitrary interference with their right to procreation.

  5. Orbital tuning of deep ice cores using O2/N2 of trapped air

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Aoki, S.; Nakazawa, T.

    2014-12-01

    The chronology of the first Dome Fuji deep ice core (80,000-340,000 yr BP) was established by orbital tuning of measured O2/N2 ratios in trapped air to the past local summer insolation at the drill site (Kawamura et al., 2007). The O2/N2 ratios found in ice cores are generally lower than atmospheric ratio because of size-dependent molecular fractionation during bubble close-off. The magnitude of this gas fractionation appears to be influenced by snow metamorphism when the layer was originally at the surface, which in turn is controlled by local summer insolation (Fujita et al., 2009). The O2/N2 record has little 100,000-yr periodicity (strongest in climatic records), suggesting insignificant climatic influence in the orbital tuning. Agreement of the O2/N2 chronology with U-Th radiometric chronology of speleothems (within ~2000 yr) suggests that O2/N2 and summer insolation are indeed in phase. However, it may not be common to all ice cores that O2/N2 signal only records local summer insolation. For example, the GISP2 ice core (Greenland) has clear imprint of abrupt climate changes in the O2/N2 record, indicating climatic (non-insolation) signal in the record and the possibility of phase variability of O2/N2 relative to the past insolation (Suwa and Bender, 2008). Here we present new O2/N2 record from the second Dome Fuji ice core with significant improvements in ice core storage practice and mass spectrometry. In particular, the ice core had been stored at about -50 ˚C until the air extraction except during transportations, which prevent fractionation due to gas loss during the core storage. The precision of the new O2/N2 data set is improved by a factor of 3 over the previous data, and we do not observe outliers (there were 15% outliers in the previous data). Clear imprint of local insolation is recognizable in the new O2/N2, which would enable us to generate a chronology with accuracy of ~2000 yr towards older periods. Samples from the first core after long

  6. The excitation functions of 187Re(n,2n) 186m,gRe reactions

    NASA Astrophysics Data System (ADS)

    Huang, Xiao-Long; Kang, Meng-Xiao; Liu, Li-Le; Wang, Ji-Min; Chen, Xiong-Jun

    2016-08-01

    A new value for the emission probability of 137.144 keV γ-rays from 186gRe decay is recommended to be (9.47±0.03)/%. Using this value the measured cross sections for 187Re(n,2n)186mRe and 187Re(n,2n)186gRe reactions around 14 MeV are analyzed, and the cross section for 187Re(n,2n)186m+gRe reaction at 14.8 MeV is (2213±116) mb. The UNF code was adopted to calculate the cross sections for the 187Re(n,2n)186m+gRe reaction below 20 MeV, fitting to the value (2213±116) mb at 14.8 MeV using a set of optimum neutron optical potential parameters which were obtained based on the relevant experimental data of rhenium. The isomeric cross section ratio for the 187Re(n,2n)186m,gRe reaction was analyzed using the V-H method based on nuclear statistical theory. Combining these calculated results, the excitation functions for the 187Re(n,2n)186mRe and 187Re(n,2n)186gRe reactions were obtained. The obtained results are in good agreement with the available experimental data.

  7. Effect of Ca-doping on the ionic conductivity of LiSi2N3

    NASA Astrophysics Data System (ADS)

    Narimatsu, E.; Yamamoto, Y.; Takeda, T.; Nishimura, T.; Hirosaki, N.

    2011-05-01

    Effect of Ca-doping on the ionic conductivity of LiSi2N3 was studied. The compositions of Li1-2xCaxSi2N3 (x=0-0.2) were synthesized by the reaction of Li3N, Si3N4, and Ca3N2 at temperature of 1873K-2073K. Ca was incorporated into the LiSi2N3 host lattice and formed the solid solution, Li1-2xCaxSi2N3. Activation energy for ionic conduction was decreased and ionic conductivity at room temperature was enhanced by Ca doping. At 298K, the ionic conductivity of densified Li1-2xCaxSi2N3 (x=0.075) ceramics achieved 1.6×10-5Sm-1, almost 4 orders of magnitude higher than that of densified Li1-2xCaxSi2N3(x=0) ceramics (3.1×10-9Sm-1). The LiSi2N3 framework change by Ca doping decreased the interaction between the ions and increased the defects of the structure. Thus, mobile Li+ ion could migrate easier. Moreover, incorporation of aliovalent substitutional Ca2+ ions in the LiSi2N3 lattice might be expected to create a Li+ vacancy (VLi) for charge compensation (Li1-2xCaxVLiSi2N3), thereby increasing the number of mobile Li+ ions.

  8. YpT1-2N0 rectal cancer after neoadjuvant chemoradiation has lower survival compared with pT1-2N0 rectal cancer

    PubMed Central

    Wan, Jue-feng; Zhu, Ji; Li, Gui-chao; Sun, Wen-jie; Zhang, Zhen

    2015-01-01

    Pathologic T1-2N0 rectal cancer shows an excellent prognosis without preoperative or postoperative chemoradiation. However, oncologic outcome of ypT1-2N0 remains unclear and undetermined. Thus, the aim of this study was to compare the survival of ypT1-2 and pT1-2 rectal cancer patients after radical resection and identify risk factors of ypT1-2 rectal cancer in Surveillance, Epidemiology, and End Results Program (SEER)-registered rectal cancer patients. The results showed that ypT1-2N0 rectal cancer after neoadjuvant chemoradiation has lower survival compared with pT1-2N0 rectal cancer and mucinous/signet-ring cancer and less than 12 lymph nodes retrieval were two risk factors in ypT1-2 patients. These results suggest that ypT1-2 patients with one or two risk factors may benefit from postoperative adjuvant chemotherapy. PMID:26517674

  9. Anomeric effects in sulfonyl compounds: an experimental and computational study of fluorosulfonyl azide, FSO(2)N(3), and trifluoromethylsulfonyl azide, CF(3)SO(2)N(3).

    PubMed

    Zeng, Xiaoqing; Gerken, Michael; Beckers, Helmut; Willner, Helge

    2010-07-22

    Fluorosulfonyl azide, FSO(2)N(3), was characterized by IR (gas phase, Ar matrix), and Raman (liquid) spectroscopy. According to the matrix IR spectrum of (18)O-labeled FSO(2)N(3), its two oxygen atoms are nonequivalent. This assumption was confirmed by the X-ray crystal structure of FSO(2)N(3) at -123 degrees C, as only one conformer was observed with one of the S=O bonds in synperiplanar position to the N(3) group (phi(OS-NN) = -14.8(3) degrees) with respect to the S-N bond. The same conformation was found for trifluoromethylsulfonyl azide, CF(3)SO(2)N(3) (phi(OS-NN) = -23.74(15) degrees), in the solid state. The preference of such a synperiplanar configuration between S=O and N(3) was rationalized by a predominant anomeric interaction of n(sigma)(N) --> sigma*(S-O), as supported by the experiment and quantum chemical calculations.

  10. $\\frac{{\\rm SO}(2N)}{U(N)}$ Riccati-Hartree-Bogoliubov equation based on the SO(2N) Lie algebra of the fermion operators

    NASA Astrophysics Data System (ADS)

    Nishiyama, Seiya; da Providência, João

    2015-02-01

    In this paper we present the induced representation of SO(2N) canonical transformation group and introduce (SO(2N))/(U(N)) coset variables. We give a derivation of the time-dependent Hartree-Bogoliubov (TDHB) equation on the Kähler coset space (G)/(H) = (SO(2N))/(U(N)) from the Euler-Lagrange equation of motion for the coset variables. The TDHB wave function represents the TD behavior of Bose condensate of fermion pairs. It is a good approximation for the ground state of the fermion system with a pairing interaction, producing the spontaneous Bose condensation. To describe the classical motion on the coset manifold, we start from the local equation of motion. This equation becomes a Riccati-type equation. After giving a simple two-level model and a solution for a coset variable, we can get successfully a general solution of time-dependent Riccati-Hartree-Bogoliubov equation for the coset variables. We obtain the Harish-Chandra decomposition for the SO(2N) matrix based on the nonlinear Möbius transformation together with the geodesic flow on the manifold.

  11. Study of Ag transport in Cr2N0.61-7Ag nanocomposite thin film due to thermal exposition

    NASA Astrophysics Data System (ADS)

    Bílek, P.; Jurči, P.; Podgornik, B.; Jenko, D.; Hudáková, M.; Kusý, M.

    2015-12-01

    Cr2N0.61-7Ag nanocomposite coatings were deposited on substrates made of Cr-V ledeburitic tool steel Vanadis 6 using reactive magnetron sputtering at a deposition temperature of 500 °C. Investigations of as-deposited films and annealing experiments in closed-air atmosphere at temperatures of 300, 400 and 500 °C and the durations up to 24 h, followed by quantitative scanning electron microscopy, transmission electron microscopy, Auger electron spectroscopy and X-ray diffraction revealed that the films were composed of Cr2N0.61 matrix and individual silver agglomerates located along columnar crystals of the matrix. The maximal size of Ag-agglomerates was 80 nm. The surface population density of silver agglomerates increased with prolonging the annealing time up to 2 h and then decreased. The increase was more pronounced at lower annealing temperatures. This behaviour was referred to the competition between three phenomena, namely the transport of detached Ag atoms to the free surface, formation of oxide layer on the surface and sublimation of silver from the surface. At lower temperatures and/or shorter annealing times, the Ag-transport to the free surface was determined to be prevalent, thus, an increase in population density of silver agglomerates was determined. On the other hand, for higher temperatures and/or longer annealing times the population density of Ag-agglomerates rather decreased due to retarding effect of thicker oxide layer and sublimation of silver.

  12. Adaptation of Pandemic H2N2 Influenza A Viruses in Humans

    PubMed Central

    Joseph, Udayan; Linster, Martin; Suzuki, Yuka; Krauss, Scott; Halpin, Rebecca A.; Vijaykrishna, Dhanasekaran; Fabrizio, Thomas P.; Bestebroer, Theo M.; Maurer-Stroh, Sebastian; Webby, Richard J.; Wentworth, David E.; Fouchier, Ron A. M.

    2014-01-01

    The 1957 A/H2N2 influenza virus caused an estimated 2 million fatalities during the pandemic. Since viruses of the H2 subtype continue to infect avian species and pigs, the threat of reintroduction into humans remains. To determine factors involved in the zoonotic origin of the 1957 pandemic, we performed analyses on genetic sequences of 175 newly sequenced human and avian H2N2 virus isolates and all publicly available influenza virus genomes. PMID:25505070

  13. Hip-hop solutions of the 2N-body problem

    NASA Astrophysics Data System (ADS)

    Barrabés, Esther; Cors, Josep Maria; Pinyol, Conxita; Soler, Jaume

    2006-05-01

    Hip-hop solutions of the 2N-body problem with equal masses are shown to exist using an analytic continuation argument. These solutions are close to planar regular 2N-gon relative equilibria with small vertical oscillations. For fixed N, an infinity of these solutions are three-dimensional choreographies, with all the bodies moving along the same closed curve in the inertial frame.

  14. Backreaction and N{sub f} = 2N{sub c} SQCD-like theories

    SciTech Connect

    Caceres, Elena; Flauger, Raphael; Ihl, Matthias; Wrase, Timm

    2009-04-20

    We present new supergravity backgrounds generated by N{sub c} D5-branes, wrapping the S{sup 2} of the resolved conifold, in the presence of N{sub f} = 2N{sub c} smeared flavor D5-branes. The smearing allows us to take their backreaction on the geometry into account. The near horizon geometries are expected to be supergravity duals of SQCD-like theories with N{sub f} = 2N{sub c}.

  15. (RS), (R)(-) and (S)(+) derivatives of 2-N-arylalkylamino-1-butanol having antiarrhythmic properties.

    PubMed

    Eckstein, M; Zajaczkowska, J; Samochowiec, L

    1988-01-01

    A series of theophyllinyl-7'-ethyl derivatives of (RS), (R)(-) and (S)(+) 2-aminobutanol were synthesized and tested in various models of experimental arrhythmia for their preventive and curative properties; (R)(-) 2-N-theophyllinyl-7'-ethyl amino-1-butanol (1a) and (R)(-) theophyllinyl-7'-ethyl-2-N-methylamino-1-butanol (3a) hydrochlorides showed interesting antiarrhythmic properties. The levorotatory compounds of R configuration showed stronger protective and also therapeutic effect in different experimental arrhythmias.

  16. Investigation of Gd3N@C2n (40 n 44) family by Raman and inelastic electron tunneling spectroscopy

    SciTech Connect

    Burke, Brian; Chan, Jack; Williams, Keith A; Ge, Jiechao; Shu, Chunying; Fu, Wujun; Dorn, Harry C; Kushmerick, James G; Puretzky, Alexander A; Geohegan, David B

    2010-01-01

    The structure and vibrational spectrum of Gd3N@C80 is studied through Raman and inelastic electron tunneling spectroscopy as well as density-functional theory and universal force eld calculations. Hindered rotations, shown by both theory and experiment, indicate the formation of a Gd3N-C80 bond which reduces the ideal icosahedral symmetry of the C80 cage. The vibrational modes involving the movement of the encapsulated species are a ngerprint of the interaction between the fullerene cage and the core complex. We present Raman data for the Gd3N@C2n 40 n 44 family as well as Y3N@C80, Lu3N@C80, and Y3N@C88 for comparison. Conductance measurements have been performed on Gd3N@C80 and reveal a Kondo effect similar to that observed in C60.

  17. Possible observation of the dineutron in the 159Tb (n, 2n) 158gTb nuclear reaction

    NASA Astrophysics Data System (ADS)

    Kadenko, Igor

    2016-05-01

    Experimental observation of the 159\\text{Tb}(n, 2n) reaction product was performed with application of the activation technique. Tb specimen of natural composition was irradiated with (d, d) neutrons of 5.39 and 7 MeV energies. Instrumental spectra of Tb specimen were measured with HPGe spectrometer. An unexpected 944.2 keV γ-ray peak was observed. Other γ-ray lines due to 158gTb decay were identified as well. A bonded dineutron emission with the binding energy (Bdn) within limitations 1.3 \\text{MeV}dn<2.8 \\text{MeV} is evidenced by the energy of incident neutrons and by the 158gTb presence in the output channel. The specific nuclear properties of 158Tb as deformed nucleus were discussed to explain a bonded dineutron formation based on theoretical assumptions and calculations, using standard parameters for this mass region.

  18. Abnormalities of ADP/ATP carrier protein in J-2-N cardiomyopathic hamsters.

    PubMed

    Kato, M; Yang, J; Iwai, T; Tanamura, A; Arino, T; Kawashima, O; Takeda, N

    1993-02-17

    ADP/ATP carrier protein (AAC) is located in the mitochondrial inner membrane and has an important function in mitochondrial energy supply. This protein transports ATP to the cytoplasm and counter transports ADP into the mitochondria. J-2-N cardiomyopathic hamsters were investigated to determine the AAC content in cardiac mitochondria. After recording an electrocardiogram and collecting blood, the cardiac mitochondria were isolated. The mitochondrial membranes were labelled with eosin-5-maleimide (EMA) and separated on SDS polyacrylamide gels. The position of the AAC component was identified by exposing the gel under UV light, and the AAC content was determined by densitometry after staining with Coomassie blue. The AAC content ratio was significantly decreased in both 10-week-old and 1-year survived J-2-N hamsters when compared to control Golden hamster. Among 10-week-old J-2-N hamsters, the decrease in the AAC content ratio was more marked for the animals with more severe myocardial damage. The H(+)-ATPase activities of mitochondrial membrane were higher in 10-week-old J-2-N hamsters than in control hamsters. These results suggest that the decrease of AAC in J-2-N hamster plays an important role in the pathogenesis of cardiomyopathy in J-2-N hamsters. PMID:8455591

  19. Estimating Reaction Cross Sections from Measured (Gamma)-Ray Yields: The 238U(n,2n) and 239Pu(n,2n) Cross Sections

    SciTech Connect

    Younes, W

    2002-11-18

    A procedure is presented to deduce the reaction-channel cross section from measured partial {gamma}-ray cross sections. In its simplest form, the procedure consists in adding complementary measured and calculated contributions to produce the channel cross section. A matrix formalism is introduced to provide a rigorous framework for this approach. The formalism is illustrated using a fictitious product nucleus with a simple level scheme, and a general algorithm is presented to process any level scheme. In order to circumvent the cumbersome algebra that can arise in the matrix formalism, a more intuitive graphical procedure is introduced to obtain the same reaction cross-section estimate. The features and limitations of the method are discussed, and the technique is applied to extract the {sup 235}U (n,2n) and {sup 239}Pu(n,2n) cross sections from experimental partial {gamma}-ray cross sections, coupled with (enhanced) Hauser-Feshbach calculations.

  20. A Recurrent Loss-of-Function Alanyl-tRNA Synthetase (AARS) Mutation in Patients with Charcot-Marie-Tooth Disease Type 2N (CMT2N)

    PubMed Central

    McLaughlin, Heather M.; Sakaguchi, Reiko; Giblin, William; Wilson, Thomas E.; Biesecker, Leslie; Lupski, James R.; Talbot, Kevin; Vance, Jeffery M.; Züchner, Stephan; Lee, Yi-Chung; Kennerson, Marina; Hou, Ya-Ming; Nicholson, Garth; Antonellis, Anthony

    2011-01-01

    Charcot-Marie-Tooth (CMT) disease comprises a heterogeneous group of peripheral neuropathies characterized by muscle weakness and wasting, and impaired sensation in the extremities. Four genes encoding an aminoacyl-tRNA synthetase (ARS) have been implicated in CMT disease. ARSs are ubiquitously expressed, essential enzymes that ligate amino acids to cognate tRNA molecules. Recently, a p.Arg329His variant in the alanyl-tRNA synthetase (AARS) gene was found to segregate with dominant axonal CMT type 2N (CMT2N) in two French families; however, the functional consequence of this mutation has not been determined. To investigate the role of AARS in CMT, we performed a mutation screen of the AARS gene in patients with peripheral neuropathy. Our results showed that p.Arg329His AARS also segregated with CMT disease in a large Australian family. Aminoacylation and yeast viability assays showed that p.Arg329His AARS severely reduces enzyme activity. Genotyping analysis indicated that this mutation arose on three distinct haplotypes, and the results of bisulfite sequencing suggested that methylation-mediated deamination of a CpG dinucleotide gives rise to the recurrent p.Arg329His AARS mutation. Together, our data suggest that impaired tRNA charging plays a role in the molecular pathology of CMT2N, and that patients with CMT should be directly tested for the p.Arg329His AARS mutation. PMID:22009580

  1. Partial (gamma)-Ray Cross Sections for the Reaction 239Pu(n,2n(gamma)i) and the 239Pu(n,2n) Cross Section

    SciTech Connect

    Beacker, J.A.; Bernstein, L.A.; Younes, W.; McNabb, D.P.; Garrett, P.E.; Archer, D.; McGrath, C.A.; Stoyer, M.A.; Chen, H.; Ormand, W.E.; Nelson, R.O.; Chadwick, M.B.; Johns, G.D.; Drake, D.; Young, P.G.; Devlin, M.; Fotiades, N.; Wilburn, W.S.

    2001-09-14

    Absolute partial {gamma}-ray cross sections for production of discrete {gamma} rays in the {sup 239}Pu(n,2n{gamma}i){sup 238}Pu reaction have been measured. The experiments were performed at LANSCE/WNR on the 60R flight line. Reaction {gamma}-rays were measured using the large-scale Compton-suppressed array of Ge detectors, GEANIE. The motivation for this experiment, an overview of the partial {gamma}-ray cross-section measurement, and an introduction to the main experimental issues will be presented. The energy resolution of the Ge detectors allowed identification of reaction {gamma} rays above the background of sample radioactivity and fission {gamma} rays. The use of planar Ge detectors with their reduced sensitivity to neutron interactions and improved line shape was also important to the success of this experiment. Absolute partial {gamma}-ray cross sections are presented for the 6{sub 1}{sup +} {yields} 4{sub 1}{sup +} member of the ground state rotational band in {sup 238}Pu, together with miscellaneous other {gamma}-ray partial cross sections. The n,2n reaction cross section shape and magnitude as a function of neutron energy was extracted from these partial cross sections using nuclear modeling (enhanced Hauser-Feshbach) to relate partial {gamma}-ray cross sections to the n,2n cross section. The critical nuclear modeling issue is the ratio of a partial cross section to the reaction channel cross section, and not the prediction of the absolute magnitude.

  2. Nickel(II) Complexation with Nitrate in Dry [C4mim][Tf2N] Ionic Liquid: A Spectroscopic, Microcalorimetric, and Molecular Dynamics Study.

    PubMed

    Melchior, Andrea; Gaillard, Clotilde; Gràcia Lanas, Sara; Tolazzi, Marilena; Billard, Isabelle; Georg, Sylvia; Sarrasin, Lola; Boltoeva, Maria

    2016-04-01

    The complex formation of nitrate ions with nickel(II) in dry [C4mim][Tf2N] ionic liquid (IL) was investigated by means of UV-visible spectrophotometry, isothermal titration calorimetry (ITC), extended X-ray absorption fine structure spectroscopy (EXAFS), and molecular dynamics (MD) simulations. EXAFS spectroscopy and MD simulations show that the solvated Ni(II) cation is initially coordinated by the oxygens of the [Tf2N](-) anion of IL, which can behave either as mono- or bidentate. Spectroscopic and thermodynamic data show that Ni(II) is able to form up to three stable mononuclear complexes with nitrate in this solvent. The stability constants for Ni(NO3)j complexes (j = 1-3) calculated from spectrophotometry and ITC experiments decrease in the order log K1 > log K2 > log K3. The formation of the first two species is enthalpy-driven, while the third species is entropy-stabilized. The UV-vis spectra of solutions containing different nitrate/Ni(II) ratios show that the metal ion retains the six-coordinate geometry. Furthermore, the EXAFS evidences that nitrate is always bidentate. Molecular dynamics simulations show that the [Tf2N](-) anions bind Ni(II) through the sulfonyl oxygen atoms and can coordinate either as monodentate or chelate. The analysis of the MD data shows that introduction of nitrates in the first coordination sphere of the metal ion results in remarkable structural rearrangement of the ionic liquid. PMID:26999457

  3. Measurements of d2n and A1n : Probing the neutron spin structure

    NASA Astrophysics Data System (ADS)

    Flay, D.; Posik, M.; Parno, D. S.; Allada, K.; Armstrong, W. R.; Averett, T.; Benmokhtar, F.; Bertozzi, W.; Camsonne, A.; Canan, M.; Cates, G. D.; Chen, C.; Chen, J.-P.; Choi, S.; Chudakov, E.; Cusanno, F.; Dalton, M. M.; Deconinck, W.; de Jager, C. W.; Deng, X.; Deur, A.; Dutta, C.; Fassi, L. El; Franklin, G. B.; Friend, M.; Gao, H.; Garibaldi, F.; Gilad, S.; Gilman, R.; Glamazdin, O.; Golge, S.; Gomez, J.; Guo, L.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Huang, J.; Hyde, C.; Ibrahim, H. F.; Jiang, X.; Jin, G.; Katich, J.; Kelleher, A.; Kolarkar, A.; Korsch, W.; Kumbartzki, G.; LeRose, J. J.; Lindgren, R.; Liyanage, N.; Long, E.; Lukhanin, A.; Mamyan, V.; McNulty, D.; Meziani, Z.-E.; Michaels, R.; Mihovilovič, M.; Moffit, B.; Muangma, N.; Nanda, S.; Narayan, A.; Nelyubin, V.; Norum, B.; Nuruzzaman, Oh, Y.; Peng, J. C.; Qian, X.; Qiang, Y.; Rakhman, A.; Ransome, R. D.; Riordan, S.; Saha, A.; Sawatzky, B.; Shabestari, M. H.; Shahinyan, A.; Širca, S.; Solvignon, P.; Subedi, R.; Sulkosky, V.; Tobias, W. A.; Troth, W.; Wang, D.; Wang, Y.; Wojtsekhowski, B.; Yan, X.; Yao, H.; Ye, Y.; Ye, Z.; Yuan, L.; Zhan, X.; Zhang, Y.; Zhang, Y.-W.; Zhao, B.; Zheng, X.; Jefferson Lab Hall A Collaboration

    2016-09-01

    We report on the results of the E06-014 experiment performed at Jefferson Lab in Hall A, where a precision measurement of the twist-3 matrix element d2 of the neutron (d2n) was conducted. The quantity d2n represents the average color Lorentz force a struck quark experiences in a deep inelastic electron scattering event off a neutron due to its interaction with the hadronizing remnants. This color force was determined from a linear combination of the third moments of the 3He spin structure functions, g1 and g2, after nuclear corrections had been applied to these moments. The structure functions were obtained from a measurement of the unpolarized cross section and of double-spin asymmetries in the scattering of a longitudinally polarized electron beam from a transversely and a longitudinally polarized 3He target. The measurement kinematics included two average Q2 bins of 3.2 GeV2 and 4.3 GeV2 , and Bjorken-x 0.25 ≤x ≤0.90 covering the deep inelastic and resonance regions. We have found that d2n is small and negative for ⟨Q2⟩ =3.2 GeV2 , and even smaller for ⟨Q2⟩ =4.3 GeV2 , consistent with the results of a lattice QCD calculation. The twist-4 matrix element f2n was extracted by combining our measured d2n with the world data on the first moment in x of g1n, Γ1n. We found f2n to be roughly an order of magnitude larger than d2n. Utilizing the extracted d2n and f2n data, we separated the Lorentz color force into its electric and magnetic components, FEy ,n and FBy ,n, and found them to be equal and opposite in magnitude, in agreement with the predictions from an instanton model but not with those from QCD sum rules. Furthermore, using the measured double-spin asymmetries, we have extracted the virtual photon-nucleon asymmetry on the neutron A1n, the structure function ratio g1n/F1n, and the quark ratios (Δ u +Δ u ¯)/(u +u ¯) and (Δ d +Δ d ¯)/(d +d ¯). These results were found to be consistent with deep-inelastic scattering world data and with the

  4. Mixed Matrix Membranes for O2/N2 Separation: The Influence of Temperature

    PubMed Central

    Fernández-Barquín, Ana; Casado-Coterillo, Clara; Valencia, Susana; Irabien, Angel

    2016-01-01

    In this work, mixed matrix membranes (MMMs) composed of small-pore zeolites with various topologies (CHA (Si/Al = 5), LTA (Si/Al = 1 and 5), and Rho (Si/Al = 5)) as dispersed phase, and the hugely permeable poly(1-trimethylsilyl-1-propyne) (PTMSP) as continuous phase, have been synthesized via solution casting, in order to obtain membranes that could be attractive for oxygen-enriched air production. The O2/N2 gas separation performance of the MMMs has been analyzed in terms of permeability, diffusivity, and solubility in the temperature range of 298–333 K. The higher the temperature of the oxygen-enriched stream, the lower the energy required for the combustion process. The effect of temperature on the gas permeability, diffusivity, and solubility of these MMMs is described in terms of the Arrhenius and Van’t Hoff relationships with acceptable accuracy. Moreover, the O2/N2 permselectivity of the MMMs increases with temperature, the O2/N2 selectivities being considerably higher than those of the pure PTMSP. In consequence, most of the MMMs prepared in this work exceeded the Robeson’s upper bound for the O2/N2 gas pair in the temperature range under study, with not much decrease in the O2 permeabilities, reaching O2/N2 selectivities of up to 8.43 and O2 permeabilities up to 4,800 Barrer at 333 K. PMID:27196937

  5. Core-shell nano-FeS2@N-doped graphene as an advanced cathode material for rechargeable Li-ion batteries.

    PubMed

    Tan, Rui; Yang, Jinlong; Hu, Jiangtao; Wang, Kai; Zhao, Yan; Pan, Feng

    2016-01-18

    We report the formation of core-shell nano-FeS2@N-doped graphene as a novel cathode material and its mechanism for use in rechargeable Li-ion batteries. A benefit of the amount of FeS2 nano-crystals as the core for Li-ion storage with high capacity and using coated N-doped graphene as the shell is that FeS2@N-graphene exhibits a remarkable specific energy (950 W h kg(-1) at 0.15 kW g(-1)) and higher specific power (543 W h kg(-1) at 2.79 kW g(-1)) than commercial rechargeable LIB cathodes, as well as stable cycling performance (∼600 W h kg(-1) at 0.75 kW g(-1) after 400 cycles).

  6. Nanoparticles of superconducting {gamma}-Mo{sub 2}N and {delta}-MoN

    SciTech Connect

    Gomathi, A.; Sundaresan, A.; Rao, C.N.R.

    2007-01-15

    We have been able to prepare nanoparticles ({approx}4 nm diameter) of cubic {gamma}-Mo{sub 2}N by a simple procedure involving the reaction of MoCl{sub 5} with urea at 873 K. The nanoparticles show a superconducting transition around 6.5 K. The {gamma}-Mo{sub 2}N nanoparticles are readily transformed to nanoparticles of {delta}-MoN with a slightly larger diameter on heating in a NH{sub 3} atmosphere at 573 K. Phase-pure {delta}-MoN obtained by this means shows a superconducting transition around 5 K. - Graphical abstract: TEM image of the {gamma}-Mo{sub 2}N particles with the inset showing the resistivity of the sample as a function of temperature.

  7. Generation of 2N + 1-scroll existence in new three-dimensional chaos systems

    NASA Astrophysics Data System (ADS)

    Liu, Yue; Guan, Jian; Ma, Chunyang; Guo, Shuxu

    2016-08-01

    We propose a systematic methodology for creating 2N + 1-scroll chaotic attractors from a simple three-dimensional system, which is named as the translation chaotic system. It satisfies the condition a12a21 = 0, while the Chua system satisfies a12a21 > 0. In this paper, we also propose a successful (an effective) design and an analytical approach for constructing 2N + 1-scrolls, the translation transformation principle. Also, the dynamics properties of the system are studied in detail. MATLAB simulation results show very sophisticated dynamical behaviors and unique chaotic behaviors of the system. It provides a new approach for 2N + 1-scroll attractors. Finally, to explore the potential use in technological applications, a novel block circuit diagram is also designed for the hardware implementation of 1-, 3-, 5-, and 7-scroll attractors via switching the switches. Translation chaotic system has the merit of convenience and high sensitivity to initial values, emerging potentials in future engineering chaos design.

  8. A DFT study of adsorption of glycine onto the surface of BC2N nanotube

    NASA Astrophysics Data System (ADS)

    Soltani, Alireza; Azmoodeh, Zivar; Javan, Masoud Bezi; Lemeski, E. Tazikeh; Karami, Leila

    2016-10-01

    A theoretical study of structure and the energy interaction of amino acid glycine (NH2CH2COOH) with BC2N nanotube is crucial for apperception behavior occurring at the nanobiointerface. Herein, we studied the adsorption of glycine in their radical and zwitterionic forms upon the surface of BC2N nanotube using M06 functional and 6-311G** standard basis set. We also considered the different orientations of the glycine amino acid on the surface of adsorbent. Further, we found out that the stability of glycine from its carbonyl group is higher than hydroxyl and amine groups. Our results also indicated that the electronic structure of BC2N nanotube on the adsorption of glycine from its amine group is more altered than the other groups. Our study exhibits that opto-electronic property of adsorbent is changed after the glycine adsorption.

  9. Two-leg SU(2n) spin ladder: A low-energy effective field theory approach

    DOE PAGES

    Lecheminant, P.; Tsvelik, A. M.

    2015-05-07

    We present a field-theory analysis of a model of two SU(2n)-invariant magnetic chains coupled by a generic interaction preserving time reversal and inversion symmetry. Contrary to the SU(2)-invariant case the zero-temperature phase diagram of such two-leg spin ladder does not contain topological phases. Thus, only generalized Valence Bond Solid phases are stabilized when n > 1 with different wave vectors and ground-state degeneracies. In particular, we find a phase which is made of a cluster of 2n spins put in an SU(2n) singlet state. For n = 3, this cluster phase is relevant to ¹⁷³Yb ultracold atoms, with an emergentmore » SU(6) symmetry, loaded in a double-well optical lattice.« less

  10. Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

    NASA Astrophysics Data System (ADS)

    Belloche, A.; Müller, H. S. P.; Menten, K. M.; Schilke, P.; Comito, C.

    2013-11-01

    Context. The discovery of amino acids in meteorites fallen to Earth and the detection of glycine, the simplest of them, in samples returned from a comet to Earth strongly suggest that the chemistry of the interstellar medium is capable of producing such complex organic molecules and that they may be widespread in our Galaxy. Aims: Our goal is to investigate the degree of chemical complexity that can be reached in the interstellar medium, in particular in dense star-forming regions. Methods: We performed an unbiased, spectral line survey toward Sgr B2(N) and (M), two regions where high-mass stars are formed, with the IRAM 30 m telescope in the 3 mm atmospheric transmission window. Partial surveys at 2 and 1.3 mm were performed in parallel. The spectra were analyzed with a simple radiative transfer model that assumes local thermodynamic equilibrium but takes optical depth effects into account. Results: About 3675 and 945 spectral lines with a peak signal-to-noise ratio higher than 4 are detected at 3 mm toward Sgr B2(N) and (M), i.e. about 102 and 26 lines per GHz, respectively. This represents an increase by about a factor of two over previous surveys of Sgr B2. About 70% and 47% of the lines detected toward Sgr B2(N) and (M) are identified and assigned to 56 and 46 distinct molecules as well as to 66 and 54 less abundant isotopologues of these molecules, respectively. In addition, we report the detection of transitions from 59 and 24 catalog entries corresponding to vibrationally or torsionally excited states of some of these molecules, respectively, up to a vibration energy of 1400 cm-1 (2000 K). Excitation temperatures and column densities were derived for each species but should be used with caution. The rotation temperatures of the detected complex molecules typically range from ~50 to 200 K. Among the detected molecules, aminoacetonitrile, n-propyl cyanide, and ethyl formate were reported for the first time in space based on this survey, as were five rare

  11. Enhanced econazole penetration into human nail by 2-n-nonyl-1,3-dioxolane.

    PubMed

    Hui, Xiaoying; Chan, Thomas C K; Barbadillo, Sherry; Lee, Christine; Maibach, Howard I; Wester, Ronald C

    2003-01-01

    This study determines the enhancing effects of 2-n-nonyl-1,3-dioxolane on the penetration of econazole, an antifungal drug, into the deeper layers of the human nail where fungal infection resides. Aliquots (10 microL) of Econail lacquer formulation containing 0.45 mg of [(14)C]-econazole with 18% 2-n-nonyl-1,3-dioxolane (test group) or without 2-n-nonyl-1,3-dioxolane (control group) were applied twice daily for 14 days to human nails that had been washed with ethanol before each morning's application. The hydration of the nail sample was well controlled to simulate normal physiological conditions. After 14 days of dosing, the inner ventral section of the nail plate was assayed for absorbed drug content, using a micrometer-controlled drilling and nail powder removal system. The mass balance values of [(14)C]-econazole in this study were 90.8 and 96.4% for the test and control groups, respectively. The weight-normalized econazole content in the ventral/intermediate nail plate center in the test group was 6-fold greater than that in the control (p = 0.008). The total econazole absorbed into the supporting bed cotton ball in the test group was nearly 200-fold greater than that in the control group (p = 0.008) over the 14-day period. The amount of econazole after dosing in the inner part of the human nail (potential diseased area) was 11.1 +/- 2.6 (SD) microg/mg of nail powder with 2-n-nonyl-1,3-dioxolane in the lacquer and 1.78 +/- 0.32 microg/mg without 2-n-nonyl-1,3-dioxolane (p = 0.008). The surface nail contained more econazole (p = 0.004), that is, nonabsorbed drug, where 2-n-nonyl-1,3-dioxolane was not part of the dosing solution. Econazole in the support bed under the nail (the total absorbed dose) was 47.5 +/- 22.0 mg in the lacquer with 2-n-nonyl-1,3-dioxolane and 0.2 +/- 0.1 mg in the lacquer without 2-n-nonyl-1,3-dioxolane (p = 0.008). Moreover the concentration in the deep nail layer in the test group is 14,000 times higher than minimum inhibitory

  12. Measurements of d2n and A1n: Probing the neutron spin structure

    DOE PAGES

    Flay, D.; Posik, M.; Parno, D. S.; Allada, K.; Armstrong, W. R.; Averett, T.; Benmokhtar, F.; Bertozzi, W.; Camsonne, A.; Canan, M.; et al

    2016-09-06

    We report on the results of the E06-014 experiment performed at Jefferson Lab in Hall A, where a precision measurement of the twist-3 matrix elementmore » $d_2$ of the neutron ($$d_{2}^{n}$$) was conducted. This quantity represents the average color Lorentz force a struck quark experiences in a deep inelastic electron scattering event off a neutron due to its interaction with the hadronizing remnants. This color force was determined from a linear combination of the third moments of the spin structure functions $g_1$ and $g_2$ on $$^{3}$$He after nuclear corrections had been applied to these moments. The kinematics included two average $$Q^{2}$$ bins of $3.2$ GeV$$^{2}$$ and $4.3$ GeV$$^{2}$$, and Bjorken-$x$ $$0.25 \\leq x \\leq 0.90$$ covering the DIS and resonance regions. We found $d_2^n$ to be small and negative for $ = 3.2$ GeV$$^{2}$$, and smaller for $ = 4.3$ GeV$$^{2}$$, consistent with a lattice QCD calculation. The twist-4 matrix element $$f_{2}^{n}$$ was extracted by combining our $$d_{2}^{n}$$ with the world data on $$\\Gamma_{1}^{n} = \\int_{0}^{1} g_{1}^{n} dx$$. We found $$f_{2}^{n}$$ to be roughly an order of magnitude larger than $$d_{2}^{n}$$. Utilizing the extracted $$d_{2}^{n}$$ and $$f_{2}^{n}$$ data, we separated the color force into its electric and magnetic components, $$F_{E}^{y,n}$$ and $$F_{B}^{y,n}$$, and found them to be equal and opposite in magnitude, in agreement with instanton model predictions but not with those from QCD sum rules. Additionally, we have extracted the neutron virtual photon-nucleon asymmetry $$A_{1}^{n}$$, the structure function ratio $$g_{1}^{n}/F_{1}^{n}$$, and the quark ratios $$(\\Delta u + \\Delta \\bar{u})/(u + \\bar{u})$$ and $$(\\Delta d + \\Delta \\bar{d})/(d + \\bar{d})$$. Lastly, these results were found to be consistent with DIS world data and with the prediction of the constituent quark model but at odds with those of perturbative QCD at large $x$.« less

  13. NC unit trapped by fullerenes: a density functional theory study on Sc3NC@C(2n) (2n = 68, 78 and 80).

    PubMed

    Jin, Peng; Zhou, Zhen; Hao, Ce; Gao, Zhanxian; Tan, Kai; Lu, Xin; Chen, Zhongfang

    2010-10-21

    Endohedral metallofullerenes (EMFs) with a trapped cluster size larger than four are rather scarce. Inspired by a recent experimental observation, we explored the possibility of encapsulating an unusual Sc(3)NC unit in three representative fullerene cages, namely, C(68), C(78) and C(80), by means of density functional computations. The geometries, electronic and electrochemical redox properties of the corresponding EMFs, Sc(3)NC@C(2n) (2n = 68, 78 and 80), were investigated. These novel EMFs all have very favorable binding energies, implying a considerable possibility for experimental realization. The recently observed m/z = 1121 peak in the mass spectroscopy was characterized as Sc(3)NC@C(80). Notably the lowest-energy isomer of Sc(3)NC@C(78) has a non-IPR C(78) outer cage, the possibility to accommodate five atoms inside a fullerene as small as C(68) is also intriguing. Moreover, the intracluster and metal-cage covalent interactions were revealed by a quantum theory of atoms in molecules study. Infrared absorption spectra and (13)C nuclear magnetic resonance spectra were also computed to assist future experimental characterization.

  14. Synthesis, crystal structures and coordination modes of some triorganotin(IV) complexes with 2-N-propyl and 2-N-benzyl-amino-1-cyclopentene-1-dithiocarboxylates

    NASA Astrophysics Data System (ADS)

    López-Cardoso, Marcela; Vargas-Pineda, Gabriela; Román-Bravo, Perla Patricia; Rodríguez-Narváez, Cristina; Rosas-Valdez, Elena; Cea-Olivares, Raymundo

    2016-07-01

    The syntheses and characterization of six new triorganotin(IV) complexes, Ph3Sn(PrACDA) (1), Bu3Sn(PrACDA) (2), Ph3Sn(BzACDA) (3), Bu3Sn(BzACDA) (4), Me3Sn(BzACDA) (5) and Cy3Sn(BzACDA) (6) (ACDA = 2-amino-1-cyclopentene-1-carbodithioate anion) are reported. Compounds 1-6 were synthesized by the reaction between the sodium salts of 2-N-propyl- or 2-N-benzyl-2-amino-1-cyclopentene-1-carbodithioate and R3SnCl (R = Ph, Bu, Me, Cy) in a 1:1 M ratio. The complexes were characterized by elemental analyses, IR and NMR (1H, 13C and 119Sn) spectroscopy and by FAB+ mass spectrometry. The experimental data reveal that the tin atom is coordinated to the ligand by means of the two sulfur atoms from the carbodithioate group in an anisobidentate mode, while the 119Sn{1H} NMR spectra suggest a pentacoordinate metal center in 1-4 and a tetracoordinate tin atom for 5 and 6. The molecular structures of complexes 1, 3 and 5 were confirmed by single crystal X-ray diffraction analysis showing the presence of N-H···S hydrogen bonding and a distorted trigonal bipyramid geometry for the tin atoms.

  15. Tuning the electronic structures and magnetism of two-dimensional porous C2N via transition metal embedding.

    PubMed

    Du, Juan; Xia, Congxin; Xiong, Wenqi; Zhao, Xu; Wang, Tianxing; Jia, Yu

    2016-08-10

    Based on first-principles calculations, the electronic structures and magnetism are investigated in 3d transition metal (TM)-embedded porous two-dimensional (2D) C2N monolayers. Numerical results indicate that except Mn and Co atoms, other TM atoms can be embedded stably in the 2D C2N monolayer. Moreover, the magnetic moments of the TM-embedded C2N monolayer depend highly on the atomic number of the TM atoms. The Sc, Ti, V, Cr, Mn, Fe, Co and Ni atom-embedded C2N monolayers possess a ferromagnetic ground state, while embedding Cu can induce paramagnetic characteristics in the 2D C2N monolayer. Meanwhile, the Zn-embedded C2N monolayer exhibits a nonmagnetic ground state. These results indicate that the magnetism of 2D C2N monolayers can be tuned via embedding TM atoms. PMID:27476579

  16. Tuning the electronic structures and magnetism of two-dimensional porous C2N via transition metal embedding.

    PubMed

    Du, Juan; Xia, Congxin; Xiong, Wenqi; Zhao, Xu; Wang, Tianxing; Jia, Yu

    2016-08-10

    Based on first-principles calculations, the electronic structures and magnetism are investigated in 3d transition metal (TM)-embedded porous two-dimensional (2D) C2N monolayers. Numerical results indicate that except Mn and Co atoms, other TM atoms can be embedded stably in the 2D C2N monolayer. Moreover, the magnetic moments of the TM-embedded C2N monolayer depend highly on the atomic number of the TM atoms. The Sc, Ti, V, Cr, Mn, Fe, Co and Ni atom-embedded C2N monolayers possess a ferromagnetic ground state, while embedding Cu can induce paramagnetic characteristics in the 2D C2N monolayer. Meanwhile, the Zn-embedded C2N monolayer exhibits a nonmagnetic ground state. These results indicate that the magnetism of 2D C2N monolayers can be tuned via embedding TM atoms.

  17. Nilpotent orbits in classical Lie algebras over F2n and the Springer correspondence

    PubMed Central

    Xue, Ting

    2008-01-01

    We give the number of nilpotent orbits in the Lie algebras of orthogonal groups under the adjoint action of the groups over F2n. Let G be an adjoint algebraic group of type B, C, or D defined over an algebraically closed field of characteristic 2. We construct the Springer correspondence for the nilpotent variety in the Lie algebra of G. PMID:18202179

  18. 2N and 3N Systems in a Three Dimensional Formalism

    NASA Astrophysics Data System (ADS)

    Topolnicki, Kacper; Golak, Jacek; Skibiński, Roman; Elmeshneb, Alaa Eldeen; Witała, Henryk; Nogga, Andreas; Kamada, Hiroyuki

    2014-08-01

    We present an overview of our framework used to treat two- and three-nucleon (2N, 3N) systems employing three dimensional momentum eigenstates. Using a three dimensional formalism instead of the classical partial wave approach is an attractive alternative for a number of reasons, the most prominent being the very direct way of performing calculations. With the use of our tools it is possible to produce a working numerical realization of calculations in only a couple of steps from the fundamental (Schrödinger or Lippmann-Schwinger) equations. The FORTRAN implementations of the most complicated parts of the calculations are generated automatically by software that was written in our group. Additionally, at higher energies, three dimensional calculations avoid problems arising from slow convergence of partial wave decomposition based techniques. Our approach utilizes a very general form of the 2N and 3N forces and has been successfully used to obtain results for the 2N transition operator as well as for the 2N and 3N bound states (Golak et al. in Phys Rev C 81:034006, 2010; Few-Body Syst 53:237, 2012a; Few-Body Syst, 2012b).

  19. Angular momentum saturation in the /sup 209/Bi( ,2n) reaction

    SciTech Connect

    Mukherjee, P.; Mukherjee, I.; Sen, P.; Samanta, C.

    1987-09-01

    The measured yield of the (39/2 isomer in /sup 211/At from the reaction /sup 209/Bi( ,2n)= indicates angular momentum saturation at 44--48 MeV of incident alpha energy. The average angular momentum in the evaporation residue /sup 211/At is estimated to be 18h-dash-bar.

  20. Synthesis of phase-pure U2N3 microspheres and its decomposition into UN.

    PubMed

    Silva, Chinthaka M; Hunt, Rodney D; Snead, Lance L; Terrani, Kurt A

    2015-01-01

    Uranium mononitride (UN) is important as a nuclear fuel. Fabrication of UN in its microspherical form also has its own merits since the advent of the concept of accident-tolerant fuel, where UN is being considered as a potential fuel in the form of TRISO particles. However, not many processes have been well established to synthesize kernels of UN. Therefore, a process for synthesis of microspherical UN with a minimum amount of carbon is discussed herein. First, a series of single-phased microspheres of uranium sesquinitride (U2N3) were synthesized by nitridation of UO2+C microspheres at a few different temperatures. Resulting microspheres were of low-density U2N3 and decomposed into low-density UN. The variation of density of the synthesized sesquinitrides as a function of its chemical composition indicated the presence of extra (interstitial) nitrogen atoms corresponding to its hyperstoichiometry, which is normally indicated as α-U2N3. Average grain sizes of both U2N3 and UN varied in a range of 1-2.5 μm. These also had a considerably large amount of pore spacing, indicating the potential sinterability of UN toward its use as a nuclear fuel.

  1. SOSpin, a C++ library for Yukawa decomposition in SO(2 N) models

    NASA Astrophysics Data System (ADS)

    Cardoso, Nuno; Emmanuel-Costa, David; Gonçalves, Nuno; Simões, C.

    2016-06-01

    We present in this paper the SOSpin library, which calculates an analytic decomposition of the Yukawa interactions invariant under SO(2N) in terms of an SU(N) basis. We make use of the oscillator expansion formalism, where the SO(2N) spinor representations are expressed in terms of creation and annihilation operators of a Grassmann algebra acting on a vacuum state. These noncommutative operators and their products are simulated in SOSpin through the implementation of doubly-linked-list data structures. These data structures were determinant to achieve a higher performance in the simplification of large products of creation and annihilation operators. We illustrate the use of our library with complete examples of how to decompose Yukawa terms invariant under SO(2N) in terms of SU(N) degrees of freedom for N=2N=2 and 5. We further demonstrate, with an example for SO(4), that higher dimensional field-operator terms can also be processed with our library. Finally, we describe the functions available in SOSpin that are made to simplify the writing of spinors and their interactions specifically for SO(10) models.

  2. TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2N)

    Atmospheric Science Data Center

    2015-01-30

    TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2N) News:  TES News ... L2 Platform:  TES/Aura L2 Carbon Dioxide Spatial Coverage:  5.2 x 8.5 km nadir ... Subset Data: TES Order Tool Parameters:  Carbon Dioxide Order Data:  Reverb:   Order Data ...

  3. Expression of α5 integrin rescues fibronectin responsiveness in NT2N CNS neuronal cells

    PubMed Central

    Meland, Marit N.; Herndon, Mary E.; Stipp, Christopher S.

    2010-01-01

    The extracellular matrix protein fibronectin is implicated in neuronal regeneration in the peripheral nervous system. In the central nervous system (CNS), fibronectin is upregulated at sites of penetrating injuries and stroke; however, CNS neurons downregulate the fibronectin receptor, α5β1 integrin, during differentiation and generally respond poorly to fibronectin. NT2N CNS neuron-like cells (derived from NT2 precursor cells) have been used in pre-clinical and clinical studies for treatment of stroke and a variety of CNS injury and disease models. Here we show that, like primary CNS neurons, NT2N cells downregulate α5β1 integrin during differentiation and respond poorly to fibronectin. The poor neurite outgrowth by NT2N cells on fibronectin can be rescued by transducing NT2 precursors with a retroviral vector expressing α5 integrin under the control of the Murine Stem Cell Virus 5′ long terminal repeat. Sustained α5 integrin expression is compatible with the CNS-like neuronal differentiation of NT2N cells and does not prevent robust neurite outgrowth on other integrin ligands. Thus, α5 integrin expression in CNS neuronal precursor cells may provide a strategy for enhancing the outgrowth and survival of implanted cells in cell replacement therapies for CNS injury and disease. PMID:19598247

  4. The parafermion Fock space and explicit \\mathfrak{so}(2n+1) representations

    NASA Astrophysics Data System (ADS)

    Stoilova, N. I.; Van der Jeugt, J.

    2008-02-01

    The defining relations (triple relations) of n pairs of parafermion operators f±j (j = 1, ..., n) are known to coincide with a set of defining relations for the Lie algebra \\mathfrak{so}(2n+1) in terms of 2n generators. With the common Hermiticity conditions, this means that the 'parafermions of order p' correspond to a finite-dimensional unitary irreducible representation W(p) of \\mathfrak{so}(2n+1) , with highest weight \\big(\\frac{p}{2}, \\frac{p}{2},\\ldots,\\frac{p}{2}\\big) . Although the dimension and the character of W(p) is known by classical formulae, there is no explicit basis of W(p) available in which the parafermion operators have a natural action. In this paper we construct an orthogonal basis for W(p), and present the explicit actions of the parafermion generators on these basis vectors. We use group theoretical techniques, in which the \\mathfrak{u}(n) subalgebra of \\mathfrak{so}(2n+1) plays a crucial role: a set of Gelfand-Zetlin patterns of \\mathfrak{u}(n) will be used to label the basis vectors of W(p), and also in the explicit action (matrix elements) certain \\mathfrak{u}(n) Clebsch-Gordan coefficients are essential.

  5. Synthesis of phase-pure U2N3 microspheres and its decomposition into UN

    DOE PAGES

    Silva, Chinthaka M.; Hunt, Rodney Dale; Snead, Lance Lewis; Terrani, Kurt A.

    2014-12-12

    Uranium mononitride (UN) is important as a nuclear fuel. Fabrication of UN in its microspherical form also has its own merits since the advent of the concept of accident-tolerant fuel, where UN is being considered as a potential fuel in the form of TRISO particles. But, not many processes have been well established to synthesize kernels of UN. Therefore, a process for synthesis of microspherical UN with a minimum amount of carbon is discussed herein. First, a series of single-phased microspheres of uranium sesquinitride (U2N3) were synthesized by nitridation of UO2+C microspheres at a few different temperatures. Resulting microspheres weremore » of low-density U2N3 and decomposed into low-density UN. The variation of density of the synthesized sesquinitrides as a function of its chemical composition indicated the presence of extra (interstitial) nitrogen atoms corresponding to its hyperstoichiometry, which is normally indicated as α-U2N3. Average grain sizes of both U2N3 and UN varied in a range of 1–2.5 μm. In addition, these had a considerably large amount of pore spacing, indicating the potential sinterability of UN toward its use as a nuclear fuel.« less

  6. TAGS 85/2N RTG Power for Viking Lander Capsule

    DOE R&D Accomplishments Database

    1969-08-01

    Results of studies performed by Isotopes, Inc., Nuclear Systems Division, to optimize and baseline a TAGS 85/2N RTG for the Viking Lander Capsule prime electrical power source are presented. These studies generally encompassed identifying the Viking RTG mission profile and design requirements, and establishing a baseline RTG design consistent with these requirements.

  7. Germline Defects Caused by Smed-boule RNA-Interference Reveal That Egg Capsule Deposition Occurs Independently of Fertilization, Ovulation, Mating, or the Presence of Gametes in Planarian Flatworms.

    PubMed

    Steiner, Jessica Kathryne; Tasaki, Junichi; Rouhana, Labib

    2016-05-01

    Few animals are known to lay eggs in the absence of ovulation or copulation, as it is presumably energetically wasteful and subjected to negative selection. Characterization of Smed-boule, a member of the DAZ family of germline RNA-binding proteins, revealed that egg capsule (or capsule) production and deposition occurs independently of the presence of gametes in the planarian flatworm Schmidtea mediterranea. Reduction of Smed-boule expression by RNA-interference (RNAi) causes ablation of spermatogonial stem cells and the inability of ovarian germline stem cells to undergo oogenesis. Although animals subjected to Smed-boule RNAi lose their gametes and become sterile, they continue to lay egg capsules. Production of sterile capsules is even observed in virgin Smed-boule(RNAi) and control planarians maintained in complete isolation, demonstrating that egg production in S. mediterranea occurs independently of ovulation, fertilization, or mating. Evidence suggests that this is a conserved feature amongst Platyhelminthes, and therefore relevant to the pathology and dissemination of parasitic flatworms. These findings demonstrate that Smed-boule functions at different stages during male and female germline stem cell development, and also demonstrate that egg capsule production by planarian flatworms occurs independently of signals produced by mating or ova. PMID:27149082

  8. Germline Defects Caused by Smed-boule RNA-Interference Reveal That Egg Capsule Deposition Occurs Independently of Fertilization, Ovulation, Mating, or the Presence of Gametes in Planarian Flatworms

    PubMed Central

    Steiner, Jessica Kathryne; Tasaki, Junichi; Rouhana, Labib

    2016-01-01

    Few animals are known to lay eggs in the absence of ovulation or copulation, as it is presumably energetically wasteful and subjected to negative selection. Characterization of Smed-boule, a member of the DAZ family of germline RNA-binding proteins, revealed that egg capsule (or capsule) production and deposition occurs independently of the presence of gametes in the planarian flatworm Schmidtea mediterranea. Reduction of Smed-boule expression by RNA-interference (RNAi) causes ablation of spermatogonial stem cells and the inability of ovarian germline stem cells to undergo oogenesis. Although animals subjected to Smed-boule RNAi lose their gametes and become sterile, they continue to lay egg capsules. Production of sterile capsules is even observed in virgin Smed-boule(RNAi) and control planarians maintained in complete isolation, demonstrating that egg production in S. mediterranea occurs independently of ovulation, fertilization, or mating. Evidence suggests that this is a conserved feature amongst Platyhelminthes, and therefore relevant to the pathology and dissemination of parasitic flatworms. These findings demonstrate that Smed-boule functions at different stages during male and female germline stem cell development, and also demonstrate that egg capsule production by planarian flatworms occurs independently of signals produced by mating or ova. PMID:27149082

  9. Displacement behavior of CH4 adsorbed on coals by injecting pure CO2, N2, and CO2 N2 mixture

    NASA Astrophysics Data System (ADS)

    Shimada, Sohei; Li, Huoyin; Oshima, Yoshito; Adachi, Kazuhide

    2005-11-01

    Gas adsorption isotherms of Akabira coals were established for pure carbon dioxide (CO2), methane (CH4), and nitrogen (N2). Experimental data fit well into the Langmuir model. The ratio of sorption capacity of CO2, CH4, and N2 is 8.5:3.5:1 at a lower pressure (1.2 MPa) regime and becomes 5.5:2:1 when gas pressure increases to 6.0 MPa. The difference in sorption capacity of these three gases is explained by differences in the density of the three gases with increasing pressure. A coal methane system partially saturated with CH4 at 2.4 MPa adsorption pressure was experimentally studied. Desorption behavior of CH4 by injecting pure CO2 (at 3.0, 4.0, 5.0, and 6.0 MPa), and by injecting the CO2 N2 mixture and pure N2 (at 3.0 and 6.0 MPa) were evaluated. Results indicate that the preferential sorption property of coal for CO2 is significantly higher than that for CH4 or N2. CO2 injection can displace almost all of the CH4 adsorbed on coal. When modeling the CH4 CO2 binary and CH2 CO2 N2 ternary adsorption system by using the extended Langmuir (EL) equation, the EL model always over-predicted the sorbed CO2 value with a lower error, while under-predicting the sorbed CH4 with a higher error. A part of CO2 may dissolve into the solid organic structure of coal, besides its competitive adsorption with other gases. According to this explanation, the EL coefficients of CO2 in EL equation were revised. The revised EL model proved to be very accurate in predicting sorbed ratio of multi-component gases on coals.

  10. Exploring molecular complexity with ALMA (EMoCA): Alkanethiols and alkanols in Sagittarius B2(N2)

    NASA Astrophysics Data System (ADS)

    Müller, Holger S. P.; Belloche, Arnaud; Xu, Li-Hong; Lees, Ronald M.; Garrod, Robin T.; Walters, Adam; van Wijngaarden, Jennifer; Lewen, Frank; Schlemmer, Stephan; Menten, Karl M.

    2016-03-01

    Context. Over the past five decades, radio astronomy has shown that molecular complexity is a natural outcome of interstellar chemistry, in particular in star forming regions. However, the pathways that lead to the formation of complex molecules are not completely understood and the depth of chemical complexity has not been entirely revealed. In addition, the sulfur chemistry in the dense interstellar medium is not well understood. Aims: We want to know the relative abundances of alkanethiols and alkanols in the Galactic center source Sagittarius B2(N2), the northern hot molecular core in Sgr B2(N), whose relatively small line widths are favorable for studying the molecular complexity in space. Methods: We investigated spectroscopic parameter sets that were able to reproduce published laboratory rotational spectra of ethanethiol and studied effects that modify intensities in the predicted rotational spectrum of ethanol. We used the Atacama Large Millimeter Array (ALMA) in its Cycles 0 and 1 for a spectral line survey of Sagittarius B2(N) between 84 and 114.4 GHz. These data were analyzed by assuming local thermodynamic equilibrium (LTE) for each molecule. Our observations are supplemented by astrochemical modeling; a new network is used that includes reaction pathways for alkanethiols for the first time. Results: We detected methanol and ethanol in their parent 12C species and their isotopologs with one 12C atom substituted by 13C; the latter were detected for the first time unambiguously in the case of ethanol. The 12C/13C ratio is ~25 for both molecules. In addition, we identified CH318 OH with a 16O/18O ratio of ~180 and a 13CH3OH/CH318 OH ratio of ~7.3. Upper limits were derived for the next larger alkanols normal- and iso-propanol. We observed methanethiol, CH3SH, also known as methyl mercaptan, including torsionally excited transitions for the first time. We also identified transitions of ethanethiol (or ethyl mercaptan), though not enough to claim a secure

  11. Kinematics of the SgrB2(N-LMH) Molecular Core

    NASA Technical Reports Server (NTRS)

    Hollis, J. M.; Pedelty, J. A.; Boboltz, D. A.; Liu, S.-Y.; Snyder, L. E.; Palmer, Patrick; Lovas, F. J.; Jewell, P. R.

    2003-01-01

    Ethyl cyanide (CH3CH2CN) emission and absorption have been imaged with the Very Large Array (VLA) toward SgrB2(N-LMH) by means of the 5(sub 15)-4(sub 14) rotational transition at 43.5 GHz (lambda approx. 7 mm). The 1.5" x 1.4" VLA beam shows two principal sources of ethyl cyanide emission: an unresolved source approx. 5" north of the LMH that is kinematically consistent with simple expansion, contraction, or small-scale turbulence, and the resolved LMH core source itself that shows kinematics indicating an edge-on rotating disk that extends 23" (approx. 0.1 pc) in the approximate east-west direction. A search for the 7(sub 07)-6(sub 06) rotational transition of the amino acid glycine (NH2CH2COOH) at 43.7 GHz toward SgrB2(N-LMH) gave negative results.

  12. Antileishmanial Activity of a Series of N2,N4-Disubstituted Quinazoline-2,4-diamines

    PubMed Central

    2015-01-01

    A series of N2,N4-disubstituted quinazoline-2,4-diamines has been synthesized and tested against Leishmania donovani and L. amazonensis intracellular amastigotes. A structure–activity and structure–property relationship study was conducted in part using the Topliss operational scheme to identify new lead compounds. This study led to the identification of quinazolines with EC50 values in the single digit micromolar or high nanomolar range in addition to favorable physicochemical properties. Quinazoline 23 also displayed efficacy in a murine model of visceral leishmaniasis, reducing liver parasitemia by 37% when given by the intraperitoneal route at 15 mg kg–1 day–1 for 5 consecutive days. Their antileishmanial efficacy, ease of synthesis, and favorable physicochemical properties make the N2,N4-disubstituted quinazoline-2,4-diamine compound series a suitable platform for future development of antileishmanial agents. PMID:24874647

  13. Structural isomers of C2N(+) - A selected-ion flow tube study

    NASA Technical Reports Server (NTRS)

    Knight, J. S.; Petrie, S. A. H.; Freeman, C. G.; Mcewan, M. J.; Mclean, A. D.

    1988-01-01

    Reactivities of the structural isomers CCN(+) and CNC(+) were examined in a selected-ion flow tube at 300 + or - 5 K. The less reactive CNC(+) isomer was identified as the product of the reactions of C(+) + HCN and C(+) + C2N2; in these reactions only CNC(+) can be produced because of energy constraints. Rate coefficients and branching ratios are reported for the reactions of each isomer with H2, CH4, NH3, H2O, C2H2, HCN, N2, O2, N2O, and CO2. Ab initio calculations are presented for CCN(+) and CNC(+); a saddle point for the reaction CCN(+) yielding CNC(+) is calculated to be 195 kJ/mol above CNC(+). The results provide evidence that the more reactive CCN(+) isomer is unlikely to be present in measurable densities in interstellar clouds.

  14. Structural isomers of C2N+: a selected-ion flow tube study.

    PubMed

    Knight, J S; Petrie, S A; Freeman, C G; McEwan, M J; McLean, A D; DeFrees, D J

    1988-01-01

    Reactivities of the structural isomers CCN+ and CNC+ were examined in a selected-ion flow tube at 300 +/- 5 K. The less reactive CNC+ isomer was identified as the product of the reactions of C(+) + HCN and C(+) + C2N2; in these reactions only CNC+ can be produced because of energy constraints. Rate coefficients and branching ratios are reported for the reactions of each isomer with H2, CH4, NH3, H2O, C2H2, HCN, N2, O2, N2O, and CO2. Ab initio calculations are presented for CCN+ and CNC+; a saddle point for the reaction CCN+ --> CNC+ is calculated to be 195 kJ mol-1 above the CNC+. The results provide evidence that the more reactive CCN+ isomer is unlikely to be present in measurable densities in interstellar clouds.

  15. Highly eccentric hip-hop solutions of the 2 N-body problem

    NASA Astrophysics Data System (ADS)

    Barrabés, Esther; Cors, Josep M.; Pinyol, Conxita; Soler, Jaume

    2010-02-01

    We show the existence of families of hip-hop solutions in the equal-mass 2 N-body problem which are close to highly eccentric planar elliptic homographic motions of 2 N bodies plus small perpendicular non-harmonic oscillations. By introducing a parameter ɛ, the homographic motion and the small amplitude oscillations can be uncoupled into a purely Keplerian homographic motion of fixed period and a vertical oscillation described by a Hill type equation. Small changes in the eccentricity induce large variations in the period of the perpendicular oscillation and give rise, via a Bolzano argument, to resonant periodic solutions of the uncoupled system in a rotating frame. For small ɛ≠0, the topological transversality persists and Brouwer’s fixed point theorem shows the existence of this kind of solutions in the full system.

  16. Fabrication and electrical properties of p-CuAlO2/(n-, p-)Si heterojunctions

    NASA Astrophysics Data System (ADS)

    Suzhen, Wu; Zanhong, Deng; Weiwei, Dong; Jingzhen, Shao; Xiaodong, Fang

    2014-04-01

    CuAlO2 thin films have been prepared by the chemical solution deposition method on both n-Si and p-Si substrates. X-ray diffraction analysis indicates that the obtained CuAlO2 films have a single delafossite structure. The current transport properties of the resultant p-CuAlO2/n-Si and p-CuAlO2/p-Si heterojunctions are investigated by current-voltage measurements. The p-CuAlO2/n-Si has a rectifying ratio of ~35 within the applied voltages of -3.0 to +3.0 V, while the p-CuAlO2/p-Si shows Schottky diode-like characteristics, dominated in forward bias by the flow of space-charge-limited current.

  17. Correlation functions of Sp(2 n) invariant higher-spin systems

    NASA Astrophysics Data System (ADS)

    Skvortsov, Evgeny; Sorokin, Dmitri; Tsulaia, Mirian

    2016-07-01

    We study the general structure of correlation functions in an Sp(2 n)-invariant formulation of systems of an infinite number of higher-spin fields. For n = 4 , 8 and 16 these systems comprise the conformal higher-spin fields in space-time dimensions D = 4 , 6 and 10, respectively, while when n = 2, one deals with conventional D = 3 conformal field theories of scalars and spinors. We show that for n > 2 the Sp(2 n) symmetry and current conservation makes the 3-point correlators of two (rank-one or rank-two) conserved currents with a scalar operator be that of free theory. This situation is analogous to the one in conventional conformal field theories, where conservation of higher-spin currents implies that the theories are free.

  18. Transistor step stress testing program for JANTX2N2369A

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The effect is reported of power/temperature step stress when applied to the transistor JANTX2N2369A manufactured by Raytheon and National Semiconductor. A total of 48 samples from each manufacturer was submitted to the process. In addition, two control sample units were maintained for verification of the electrical parametric testing. The power/thermal stress tests are described, and failure analyses are presented.

  19. Porous Triphenylbenzene-Based Bicyclooxacalixarene Cage for Selective Adsorption of CO2/N2.

    PubMed

    Wang, Zhen; Luo, Yi; Zhai, Tian-Long; Ma, Hui; Chen, Jing-Jing; Shu, Yuanjie; Zhang, Chun

    2016-09-16

    A bicyclooxacalixarene cage with triangular prism structure was synthesized by a one-pot SNAr reaction. The structure of the oxacalixarene cage 1 was characterized by NMR, MS spectra, and X-ray crystal structure analyses. In the solid state, the molecular cage was assembled into an interlaced porous network structure. Gas adsorption studies indicated that cage 1 exhibited high CO2/N2 selectivity of 106. PMID:27585239

  20. Transistor step stress testing program for JANTX2N2905A

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The effect of power/temperature step stress when applied to the transistor JANTX2N2905A manufactured by Texas Instruments and Motorola is reported. A total of 48 samples from each manufacturer was submitted to the process outlined. In addition, two control sample units were maintained for verification of the electrical parametric testing. All test samples were subjected to the electrical tests outlined in Table 2 after completing the prior power/temperature step stress point.

  1. Nqrs Data for C24H42Li2N4 (Subst. No. 1587)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume B 'Substances Containing C10H16 … Zn' of Volume 48 'Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains an extract of Section '3.2 Data tables' of the Chapter '3 Nuclear quadrupole resonance data' providing the NQRS data for C24H42Li2N4 (Subst. No. 1587)

  2. Synthesis, structural and magnetic characterization of the EuNbO 2N oxynitride

    NASA Astrophysics Data System (ADS)

    Pascual, Esteban Climent; Gutierrez, Veronica Blanco; Subda, Michal; Sáez Puche, Regino

    2008-12-01

    EuNbO 2N oxynitride was synthesized by nitridation of the EuNbO 4 precursor oxide at 1113 K in ammonia flow for 12 h. X-ray powder diffraction data revealed that the EuNbO 2N oxynitride crystallizes with the cubic perovskite-type structure, S.G. Pm3¯m and a lattice constant of a = 4.03244(10) Å. Thermogravimetric studies reveal that the oxynitride decomposes around 513 K under oxygen atmosphere, giving as a final product of decomposition the EuNbO 4 oxide. The extremely low value obtained for remanence and coercive field fully agrees the isotropic character of the 8S 7/2 ground state associated to the Eu 2+. Magnetic susceptibility measurements indicate that EuNbO 2N behaves as paramagnetic over temperature range 10-300 K, the sudden increase in the susceptibility observed below 10 K, is characteristic of the onset of a ferromagnetic behaviour with an estimated Tc = 6.2 K. The saturation moment of 6.48 μ B which is smaller than 7 μ B expected for Eu 2+ can be due to the presence of Eu 3NbO 7 impurity, confirmed by the X-ray powder diffraction data.

  3. Potential energy surface of the CO2-N2 van der Waals complex

    NASA Astrophysics Data System (ADS)

    Nasri, Sameh; Ajili, Yosra; Jaidane, Nejm-Eddine; Kalugina, Yulia N.; Halvick, Philippe; Stoecklin, Thierry; Hochlaf, Majdi

    2015-05-01

    Four-dimensional potential energy surface (4D-PES) of the atmospherically relevant CO2-N2 van der Waals complex is generated using the explicitly correlated coupled cluster with single, double, and perturbative triple excitation (CCSD(T)-F12) method in conjunction with the augmented correlation consistent triple zeta (aug-cc-pVTZ) basis set. This 4D-PES is mapped along the intermonomer coordinates. An analytic fit of this 4D-PES is performed. Our extensive computations confirm that the most stable form corresponds to a T-shape structure where the nitrogen molecule points towards the carbon atom of CO2. In addition, we located a second isomer and two transition states in the ground state PES of CO2-N2. All of them lay below the CO2 + N2 dissociation limit. This 4D-PES is flat and strongly anisotropic along the intermonomer coordinates. This results in the possibility of the occurrence of large amplitude motions within the complex, such as the inversion of N2, as suggested in the recent spectroscopic experiments. Finally, we show that the experimentally established deviations from the C2v structure at equilibrium for the most stable isomer are due to the zero-point out-of-plane vibration correction.

  4. Stably superhydrophobic (IL/TiO2)n hybrid films: Intelligent self-cleaning materials

    NASA Astrophysics Data System (ADS)

    Xin, Bingwei; Wang, Limei; Jia, Chunxiao

    2015-12-01

    Stably self-cleaning (IL/TiO2)n nanocomposites were prepared via electrostatic layer-by-layer (LbL) self-assembly technique. Positively charged [C12mim]Br and negatively charged TiO2 nanoparticles were alternatively adsorbed on the negative glass substrates to form (IL/TiO2)n layers. They were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy. Under the synergistic action of ionic liquids and TiO2 P25, in which TiO2 nanoparticles provided surface roughness while [C12mim]Br acted as lower surface tension material, glass coated with 13 bilayers of [C12mim]Br/TiO2 film arrived to superhydrophobicity with 151.7 ± 2°. Owing to the photoresponsive and photocatalytic properties of TiO2, (IL/TiO2)n nanocomposites achieved the reversible superhydrophobic and superhydrophilic transition upon alternating UV irradiation and storage in the dark, and presented good performance for photocatalytic degradation of methyl orange with ultraviolet (UV) illumination. Significantly, they could be recycled for several times without obvious fatigue.

  5. Fragrance material review on 3-methyl-2-(n-pentanyl)-2-cyclopenten-1-one.

    PubMed

    Scognamiglio, J; Jones, L; Letizia, C S; Api, A M

    2012-10-01

    A toxicologic and dermatologic review of 3-methyl-2-(n-pentanyl)-2-cyclopenten-1-one when used as a fragrance ingredient is presented. 3-methyl-2-(n-pentanyl)-2-cyclopenten-1-one is a member of the fragrance structural group ketones cyclopentanones and cyclopentenones. The common characteristic structural element of the group members is a cyclopentanone or cyclopentenone ring with a straight or branched chain alkane or alkene substituent. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 3-methyl-2-(n-pentanyl)-2-cyclopenten-1-one were evaluated then summarized and includes physical properties, acute toxicity, skin irritation, mucous membrane (eye) irritation, and skin sensitization data. A safety assessment of the entire ketones cyclopentanones and cyclopentenones will be published simultaneously with this document; please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all ketones cyclopentanones and cyclopentenones in fragrances.

  6. Highly CO2/N2-switchable zwitterionic surfactant for pickering emulsions at ambient temperature.

    PubMed

    Liu, Pingwei; Lu, Weiqiang; Wang, Wen-Jun; Li, Bo-Geng; Zhu, Shiping

    2014-09-01

    Cross-linked polymer particles were prepared via surfactant-free emulsion copolymerization of 2-(diethylamino)ethyl methacrylate (DEAEMA) and sodium methacrylate (SMA) using N,N'-methylenebis(acrylamide) (MBA) as a cross-linker. Generated particles are zwitterionic, possessing unique isoelectric points in the pH range of 7.5-8.0, which is readily tunable through CO2/N2 bubbling. The particles were found to be highly responsive to CO2/N2 switching, dissolving in water with CO2 bubbling and precipitating with N2 bubbling at room temperature. Pickering emulsions of n-dodecane were prepared using these particles as the sole emulsifier. These emulsions can be rapidly demulsified with CO2 bubbling, resulting in complete oil/water phase separations. Nitrogen bubbling efficiently re-emulsifies the oil with the aid of homogenization. The rapid emulsification/demulsification using CO2/N2 bubbling at room temperature provides these cross-linked zwitterionic particles with distinct advantages as functional Pickering surfactants.

  7. Comparing the computational complexity of the PNN, the PDM, and the MMNN (M2N2)

    NASA Astrophysics Data System (ADS)

    Chettri, Samir R.; Murakami, Yoshimichi; Nagano, Isamu; Garegnani, Jerry

    1998-03-01

    In classification, the goal is to assign an input vector to a discrete number of output classes. Classifier design has a long history and they have been put to a large number of uses. In this paper we continue the task of categorizing classifiers by their computational complexity as begun. In particular, we derive analytical formulas for the number of arithmetic operations in the probabilistic neural network (PNN) and its polynomial expansion, also known as the polynomial discriminant method (PDM) and the mixture model neural network (M2N2). In addition we perform tests of the classification accuracy of the PDM with respect to the PNN and the M2N2 find that all three are close in accuracy. Based on this research we now have the ability to choose one or the other based on the computational complexity, the memory requirements and the size of the training set. This is a great advantage in an operational environment. We also discus the extension of such methods to hyperspectral data and find that only the M2N2 is suitable for application to such data.

  8. Synthesis, characterization and thermal properties of small R2R‧2N+X--type quaternary ammonium halides

    NASA Astrophysics Data System (ADS)

    Busi, Sara; Lahtinen, Manu; Mansikkamäki, Heidi; Valkonen, Jussi; Rissanen, Kari

    2005-06-01

    Twenty-one R2R'2N +X- -type ( R=methyl or ethyl, R'=alkyl, X=Br or I) quaternary ammonium (QA) halides have been prepared by using a novel one-pot synthetic route in which a formamide (dimethyl-, diethylformamide, etc.) is treated with alkyl halide in the presence of sodium or potassium carbonate. The formation of QA halides was verified with 1H-NMR, 13C-NMR, MS and elemental analysis. The crystal structures of four QA halides (two bromide and two iodide) were determined using X-ray single crystal diffraction, and the powder diffraction method was used to study the structural similarities between the single crystal and microcrystalline bulk material. The thermal properties of all compounds were studied using TG/DTA and DSC methods. The smallest compounds decomposed during or before melting. The decreasing trend of melting points was observed when the alkyl chain length was increased. The liquid ranges of 120-180 °C were observed for compounds with 5-6 carbon atoms in the alkyl chain. The low melting points and wide liquid ranges suggest potential applicability of these compounds for example as ionic liquids precursors.

  9. Tris(dimethylamino)oxosulfonium difluorotrimethylsilicate, (Me(2)N)(3)SO(+)Me(3)SiF(2)(-) (TAOS Fluoride).

    PubMed

    Wessel, Jens; Behrens, Ulrich; Lork, Enno; Borrmann, Tobias; Stohrer, Wolf-Dieter; Mews, Rüdiger

    2002-09-01

    In the OSF(4)/Me(2)NSiMe(3) system besides the long known Me(2)NS(O)F(3) only the trisubstituted derivative is isolated as (Me(2)N)(3)SO(+)Me(3)SiF(2)(-) (3). Similar to (Me(2)N)(3)S(+)Me(3)SiF(2)(-) compound 3 is an excellent fluoride ion donor. With AsF(5) and HF the corresponding hexafluoroarsenate (Me(2)N)(3)SO(+)AsF(6)(-) (4) and the hydrogen bifluoride (Me(2)N)(3)SO(+)HF(2)(-) (5) are formed in almost quantitative yield. X-ray structure determinations of 3-5 surprisingly showed two different types of structures for the cation. In 3 and 5 this cation has C(3) symmetry, while in the hexafluoroarsenate 4 a (Me(2)N)(3)S(+)-like structure with C(s)() symmetry is determined. The experimental results for (Me(2)N)(3)SO(+) and (Me(2)N)(3)S(+) are compared with theoretical calculations for these cations and their isoelectronic neutral counterparts, the phosphorus amides (Me(2)N)(3)PO and (Me(2)N)(3)P, respectively.

  10. INTERACTIVE EFFECTS OF SALINITY AND TEMPERATURE ON PLANOZYGOTE AND CYST FORMATION OF ALEXANDRIUM MINUTUM (DINOPHYCEAE) IN CULTURE(1).

    PubMed

    Figueroa, Rosa Isabel; Vázquez, Jose Antonio; Massanet, Ana; Murado, Miguel Anxo; Bravo, Isabel

    2011-02-01

    The factors regulating dinoflagellate life-cycle transitions are poorly understood. However, their identification is essential to unravel the causes promoting the outbreaks of harmful algal blooms (HABs) because these blooms are often associated with the formation and germination of sexual cysts. Nevertheless, there is a lack of knowledge on the factors regulating planozygote-cyst transitions in dinoflagellates due to the difficulties of differentiating planozygotes from vegetative stages. In the present study, two different approaches were used to clarify the relevance of environmental factors on planozygote and cyst formation of the toxic dinoflagellate Alexandrium minutum Halim. First, the effects of changes in initial phosphate (P) and nitrate (N) concentrations in the medium on the percentage of planozygotes formed were examined using flow cytometry. Second, two factorial designs were used to determine how salinity (S), temperature (T), and the density of the initial cell inoculum (I) affect planozygote and resting-cyst formation. These experiments led to the following conclusions: 1. Low P/N ratios seem to induce gamete expression because the percentage of planozygotes recorded in the absence of added phosphate (-P) was significantly higher than that obtained in the absence of added nitrogen (-N), or when the concentrations of both nitrogen and phosphate were 20 times lower (N/20 + P/20). 2. Salinity (S) and temperature (T) strongly affected both planozygote and cyst formation, as sexuality in the population increased significantly as salinity decreased and temperatures increased. S, T combinations that resulted in no significant cyst formation were, however, favorable for vegetative growth, ruling out the possibility of negative effects on cell physiology. 3. The initial cell density is thought to be important for sexual cyst formation by determining the chances of gamete contact. However, the inoculum concentrations tested did not explain either

  11. Antiangiogenic properties of substituted (Z)-(±)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-ol/one analogs and their derivatives.

    PubMed

    Venkateswaran, Amudhan; Reddy, Y Thirupathi; Sonar, Vijaykumar N; Muthusamy, Venkatraj; Crooks, Peter A; Freeman, Michael L; Sekhar, Konjeti R

    2010-12-15

    In the past half century research efforts have defined a critical role for angiogenesis in tumor growth and metastasis. We previously reported that inhibition of a novel target, ENOX1, by a (Z)-2-benzylindol-3-ylmethylene) quinuclidin-3-ol, suppressed tumor angiogenesis. The present study was undertaken in order to establish structure-activity relationships for quinuclidine analogs. The angiogenesis inhibiting activity of a series of substituted (Z)-(±)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-ols (1a-1k), (Z)-2-benzylindol-3-ylmethylene)quinuclidin-3-ones (2a-2h), (Z)-(±)-2-(1H/N-methyl-indol-3-ylmethylene)quinuclidin-3-ols (3a-3b), and substituted (Z)-(±)-2-(N-benzenesulfonylindol-3-yl-methylene)quinuclidin-3-ols and their derivatives (4a-4d) that incorporate a variety of substituents in both the indole and N-benzyl moieties was evaluated using Human Umbilical Vein Endothelial Cells (HUVECs) subjected to in vitro cell migration scratch assays, tubule formation in Matrigel, cell viability and proliferation assays. In total, 25 different analogs were evaluated. Based on in vitro cell migration scratch assays, eight analogs were identified as potent angiogenesis inhibitors at 10 μM, a concentration that was determined to be nontoxic by colony formation assay. In addition, this approach identified a potent antiangiogenic ENOX1 inhibitor, analog 4b.

  12. Two classes of stacked central configurations for the spatial 2n+1-body problem: Nested regular polyhedra plus one

    NASA Astrophysics Data System (ADS)

    Su, Xia; Deng, Chunhua

    2014-02-01

    In this paper we consider 2n mass points located at the vertices of two nested regular polyhedra with the same number of vertices and the (2n+1)th mass located at the geometrical center of the nested regular polyhedra. We show the existence of central configurations for any given mass ratios and the size ratio of nested polyhedra.

  13. The Interstellar Detection of CH_3NCO in Sgr B2(N)

    NASA Astrophysics Data System (ADS)

    Halfen, DeWayne T.; Ilyushin, V.; Ziurys, Lucy M.

    2016-06-01

    A new interstellar molecule, CH_3NCO (methyl isocyanate), has been detected for the first time using the 12 m telescope of the Arizona Radio Observatory (ARO). CH_3NCO was identified in spectra covering 68 - 116 GHz in the 3 mm segment of a broadband survey of Sgr B2(N). This study was based on previous laboratory work by Koput (1986) and new Fourier transform millimeter-wave (FTmmW) measurements performed at Arizona in the 60 - 88 GHz range. Spectroscopic constants were determined for CH_3NCO in a combined fit, and were used to predict other transitions at 3 mm. Thirty very favorable rotational lines (K_a = 0 and K_a = 1 only; E_u < 60 K) originating in five consecutive transitions of CH_3NCO in both the A and E internal rotation states were found to be present in the Sgr B2(N) survey from 68 - 105 GHz. Emission was observed at all of the predicted frequencies, with 17 lines appearing as distinct, uncontaminated spectral features, clearly showing the classic a-type, asymmetric top pattern. The CH_3NCO spectra also appear to exhibit two velocity components near VLSR ≈ 62 and 73 km s-1, both with ΔV1/2 ≈ 10 km s-1, typical of most molecules in Sgr B2(N). The fractional abundances were determined to be f = 7.6 x 10-12 and 5.0 x 10-12 for the 62 and 73 km s-1 components, relative to H_2, respectively. CH_3NCO was recently detected in volatized material from comet 67P/Churyumov-Gerasimenko by Rosetta's Philae lander.

  14. RUNX3 and CAMK2N1 hypermethylation as prognostic marker for epithelial ovarian cancer.

    PubMed

    Häfner, Norman; Steinbach, Daniel; Jansen, Lars; Diebolder, Herbert; Dürst, Matthias; Runnebaum, Ingo B

    2016-01-01

    Treatment of epithelial ovarian cancer consists of surgery plus platinum-taxane based chemotherapy. Neither prognostic nor predictive serum or tissue markers except BRCA1/2 mutations are available thus precluding individualized treatment. Aim of this study is the identification and validation of DNA-methylation markers with prognostic value. Genome-wide array analyses were used to determine methylation patterns in groups of serous EOC with different outcome (PFS < vs. > 3 years, each n = 6) but comparable clinical parameters. Two hundred and twenty differentially methylated regions in tumor tissue of patients with short vs. long PFS (106 hypo- and 114 hypermethylated regions) were identified. Thirty-five of 37 selected CpG islands were validated by MSP using the same samples as for microarray analyses. Six of these regions were analyzed by targeted next-generation bisulfite-sequencing confirming array and MSP results. Validation experiments with an enlarged patient group of Type II EOC samples (PFS <3 years n = 30; >3 years n = 18) revealed the CpG island of RUNX3 as significantly more often methylated in patients with short PFS (10/30 vs. 0/18; p < 0.01). Marker combinations with significantly different methylation frequencies in patient groups reached an increased sensitivity with equal specificity (RUNX3+CAMK2N1; sens 40%; spec 100%; p < 0.01). RUNX3/CAMK2N1 methylation-positive patients of the array-independent subset (n = 36) showed a significantly lower PFS (p < 0.01) but no other difference in clinical parameters compared to methylation-negative patients. Genome-wide methylation analyses reliably identified markers of potentially prognostic value. Hypermethylation of RUNX3/CAMK2N1 is associated with poor clinical outcome in Type II EOC, also after macroscopic complete resection. PMID:26175272

  15. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Crystal Structure and High Hardness Mechanism of Orthorhomic Si2N2O

    NASA Astrophysics Data System (ADS)

    Xiong, Lan-Tian; Cao, Mao-Sheng; Hou, Zhi-Ling

    2009-07-01

    A quasi-single-phase orthorombic Si2N2O compound is obtained by hot-pressing sintering using homogeneous precursors as raw materials under nitrogen atmosphere. The bulk hardness of orthorombic Si2N2O (o-Si2N2O) is investigated by a nanoindenter experiment; the results show that o-Si2N2O with maximal value about 19GPa has a high hardness covalent crystal besides β-Si3N4. It is discovered that the high hardness is mainly attributed to the unique crystal structure. The bridging O atoms in the o-Si2N2O are responsible for decreasing hardness. It is found that the Si-O bonds in the open tetrahedral crystal structure are more easily broken and tilted than other bonds.

  16. The 75As(n,2n) Cross Sections into the 74As Isomer and Ground State

    SciTech Connect

    Younes, W; Garrett, P E; Becker, J A; Bernstein, L A; Ormand, W E; Dietrich, F S; Nelson, R O; Devlin, M; Fotiades, N

    2003-06-30

    The {sup 75}As(n, 2n) cross section for the population of the T{sub 1/2} = 26.8-ns isomer at E{sub x} = 259.3 keV in {sup 74}As has been measured as a function of incident neutron energy, from threshold to E{sub n} = 20 MeV. The cross section was measured using the GEANIE spectrometer at LANSCE/WNR. For convenience, the {sup 75}As(n, 2n) population cross section for the {sup 74}As ground state has been deduced as the difference between the previously-known (n, 2n) reaction cross section and the newly measured {sup 75}As(n, 2n){sup 74}As{sup m} cross section. The (n, 2n) reaction, ground-state, and isomer population cross sections are tabulated in this paper.

  17. A Calcium Coordination Framework Having Permanent Porosity and High CO2/N2 Selectivity

    SciTech Connect

    Banerjee D.; Parise J.; Zhang, Z.; Plonka, A.M.; Li, J.

    2012-03-15

    A thermally stable, microporous calcium coordination network shows a reversible 5.75 wt % CO{sub 2} uptake at 273 K and 1 atm pressure, with an enthalpy of interaction of {approx}31 kJ/mol and a CO{sub 2}/N{sub 2} selectivity over 45 under ideal flue gas conditions. The absence of open metal sites in the activated material suggests a different mechanism for selectivity and high interaction energy compared to those for frameworks with open metal sites.

  18. Soil CO2, N2O and Nox Flux Responses to Biofuel Crop Plantation

    NASA Astrophysics Data System (ADS)

    Liang, L.; Eberwein, J.; Allsman, L.; Grantz, D. A.; Jenerette, D.

    2014-12-01

    Biofuel crops in high temperature environments, e.g, sorghum in southern California, USA, have a high capacity to assimilate atmospheric CO2. Photosynthates from the canopy may provide extra labile carbon source to feed soil microorganisms and influence trace gas fluxes, including CO2, N2O and NOx. Understanding how soil microorganisms balance the carbon (energy) and nitrogen (nutrients) allocation between growing microbial biomass and respiration is critical for evaluating the GHG emissions and emissions of regional air quality pollutants. We conducted experiments in a high temperature agroecosystem both in fallow and sorghum production fields with an experimental nitrogen gradient (0,50 and 100 kg/ha, marked as control, low and high with triplicate repeat) to investigate the CO2, N2O and NOx flux responses. All gas fluxes were measured simultaneously from three replicate locations for each treatment in the field biweekly. Measurements were performed 2-5 days after irrigation. We found that planting sorghum has significant effects on soil CO2 (p<0.0001), N2O (p<0.0001) and NOx (p=0.04) fluxes, but nitrogen amendments only have marginally significant effects on CO2 flux (p=0.07). Surprisingly, no significant response of N2O (p=0.27) and NOx (p=0.61) were observed in responses to N amendments. Compared to the fallow field, the CO2 flux in sorghum field increased 77%, 134% and 202% in control, low and high N level amendments, respectively. N2O flux from the sorghum field are consistently higher than from fallow field, with 207%, 174% and 1064% increase in control, low and high N level amendments, respectively. For the NOx flux, no significant difference was found between fallow and sorghum field. Although nitrogen amendments did not show significant effects on CO2, N2O and NOx flux, the high N treatment in sorghum field continuously gains the highest flux rates. Our results suggested additional C inputs may be an important factor regulating CO2, N2O and NOx fluxes in

  19. Unusual redox stability of neptunium in the ionic liquid [Hbet][Tf(2)N].

    PubMed

    Long, Kristy; Goff, George; Runde, Wolfgang

    2014-07-25

    The behavior of neptunium in the ionic liquid betaine bistriflimide, [Hbet][Tf2N], has been studied spectroscopically at room temperature and 60 °C for the first time. An unprecedented complex redox chemistry is observed, with up to three oxidation states (iv, v and vi) and up to six Np species existing simultaneously. Both redox reactions and coordination of betaine are observed for Np(iv), (v) and (vi). Elevating the temperature accelerates the coordination of Np(v) with betaine and reduction reactions slow down.

  20. A synthetic method to access symmetric and non-symmetric 2-(N,N'-disubstituted)guanidinebenzothiazoles.

    PubMed

    Cruz, Alejandro; Padilla-Martínez, Itzia I; García-Báez, Efrén V

    2012-08-24

    Symmetric and non-symmetric 2-(N-H, N-methyl, N-ethylenyl and N-aryl)guanidinebenzothiazoles were synthesized from the reaction of ammonia, methylamine, pyrrolidine and aniline with dimethyl benzo[d]thiazol-2-yl-carbonodithioimidate as intermediate. The products were characterized by ¹H-, ¹³C-NMR spectroscopy and three of them by X-ray diffraction analysis. HN-phenyl protons formed intramolecular hydrogen bonds that assist the stereochemistry of the second substituent, whereas the HN-alkyl protons were involved in intermolecular hydrogen bonding.

  1. Neutron Radiation Effect On 2N2222 And NTE 123 NPN Silicon Bipolar Junction Transistors

    NASA Astrophysics Data System (ADS)

    Oo, Myo Min; Rashid, N. K. A. Md; Karim, J. Abdul; Zin, M. R. Mohamed; Hasbullah, N. F.

    2013-12-01

    This paper examines neutron radiation with PTS (Pneumatic Transfer System) effect on silicon NPN bipolar junction transistors (2N2222 and NTE 123) and analysis of the transistors in terms of electrical characterization such as current gain after neutron radiation. The key parameters are measured with Keithley 4200SCS. Experiment results show that the current gain degradation of the transistors is very sensitive to neutron radiation. The neutron radiation can cause displacement damage in the bulk layer of the transistor structure. The current degradation is believed to be governed by increasing recombination current between the base and emitter depletion region.

  2. Electron-temperature dependence of dissociative recombination of electrons with N2/+/.N2 dimer ions

    NASA Technical Reports Server (NTRS)

    Whitaker, M.; Biondi, M. A.; Johnsen, R.

    1981-01-01

    The variation with electron temperature of the dissociative recombination of electrons with N2(+).N2 dimer ions is investigated in light of the importance of such ions in the lower ionosphere and in laser plasmas. Dissociative recombination coefficients were determined by means of a microwave afterglow mass spectrometer technique for electron temperatures from 300-5600 K and an ion and neutral temperature of 300 K. The recombination coefficient is found to be proportional to the -0.41 power of the electron temperature in this range, similar to that observed for the CO(+).CO dimer ion and consistent with the expected energy dependence for a fast dissociative process.

  3. Comet formation

    NASA Astrophysics Data System (ADS)

    Blum, J.

    2014-07-01

    There has been vast progress in our understanding of planetesimal formation over the past decades, owing to a number of laboratory experiments as well as to refined models of dust and ice agglomeration in protoplanetary disks. Coagulation rapidly forms cm-sized ''pebbles'' by direct sticking in collisions at low velocities (Güttler et al. 2010; Zsom et al. 2010). For the further growth, two model approaches are currently being discussed: (1) Local concentration of pebbles in nebular instabilities until gravitational instability occurs (Johansen et al. 2007). (2) A competition between fragmentation and mass transfer in collisions among the dusty bodies, in which a few ''lucky winners'' make it to planetesimal sizes (Windmark et al. 2012a,b; Garaud et al. 2013). Predictions of the physical properties of the resulting bodies in both models allow a distinction of the two formation scenarios of planetesimals. In particular, the tensile strength (i.e, the inner cohesion) of the planetesimals differ widely between the two models (Skorov & Blum 2012; Blum et al. 2014). While model (1) predicts tensile strengths on the order of ˜ 1 Pa, model (2) results in rather compactified dusty bodies with tensile strengths in the kPa regime. If comets are km-sized survivors of the planetesimal-formation era, they should in principle hold the secret of their formation process. Water ice is the prime volatile responsible for the activity of comets. Thermophysical models of the heat and mass transport close to the comet-nucleus surface predict water-ice sublimation temperatures that relate to maximum sublimation pressures well below the kPa regime predicted for formation scenario (2). Model (1), however, is in agreement with the observed dust and gas activity of comets. Thus, a formation scenario for cometesimals involving gravitational instability is favored (Blum et al. 2014).

  4. Canonical formalism for a 2n-dimensional model with topological mass generation

    NASA Astrophysics Data System (ADS)

    Deguchi, Shinichi

    2008-12-01

    The four-dimensional model with topological mass generation that was found by Dvali, Jackiw, and Pi has recently been generalized to any even number of dimensions (2n dimensions) in a nontrivial manner in which a Stückelberg-type mass term is introduced [S. Deguchi and S. Hayakawa, Phys. Rev. D 77, 045003 (2008)PRVDAQ0556-282110.1103/PhysRevD.77.045003]. The present paper deals with a self-contained model, called here a modified hybrid model, proposed in this 2n-dimensional generalization and considers the canonical formalism for this model. For the sake of convenience, the canonical formalism itself is studied for a model equivalent to the modified hybrid model by following the recipe for treating constrained Hamiltonian systems. This formalism is applied to the canonical quantization of the equivalent model in order to clarify observable and unobservable particles in the model. The equivalent model (with a gauge-fixing term) is converted to the modified hybrid model (with a corresponding gauge-fixing term) in a Becchi-Rouet-Stora-Tyutin-invariant manner. Thereby it is shown that the Chern-Pontryagin density behaves as an observable massive particle (or field). The topological mass generation is thus verified at the quantum-theoretical level.

  5. Structure Matters More than Size: Tuning the Electronic Properties of (TiO2)n Clusters

    NASA Astrophysics Data System (ADS)

    Marom, Noa; Bhattacharya, Saswata; Ghiringhelli, Luca

    2015-03-01

    To design (TiO2)n clusters with desired properties we implemented a suite of three genetic algorithms (GA) tailored to optimize for low total energy (EGA), high vertical electron affinity (VEA-GA), and low vertical ionization potential (VIP-GA). The property-based GAs are an extension of the cascade GA reported in. Analysis of the structures found by the VEA-GA and the VIP-GA vs. the EGA reveals structure-property relations. A high VEA is correlated with the presence of several dangling-O atoms (typically 3-4), rather than the previously suggested tri-coordinated Ti atom. A low VIP is correlated with low bond connectivity (typically 2) between two dangling-O atoms. We show that the electronic properties of (TiO2)n clusters with n up to 20 correlate more strongly with the presence of these structural features than with size. We further suggest that the presence of dangling-O atoms on TiO2 clusters or surfaces may be associated with enhanced catalytic activity and that these O atoms may serve as active sites. The process of optimization for a target property reveals the underlying structure-property relations and the structural features that may serve as active sites for catalysis. This generally applicable approach may provide valuable physical insight and design rules for better nanocatalysts.

  6. Preoperative chemoradiotherapy followed by local excision in clinical T2N0 rectal cancer

    PubMed Central

    Shin, Young Seob; Yoon, Yong sik; Lim, Seok-Byung; Yu, Chang Sik; Kim, Tae Won; Chang, Heung Moon; Park, Jin-hong; Ahn, Seung Do; Lee, Sang-Wook; Choi, Eun Kyung; Kim, Jin Cheon; Kim, Jong Hoon

    2016-01-01

    Purpose To investigate whether preoperative chemoradiotherapy (PCRT) followed by local excision (LE) is feasible approach in clinical T2N0 rectal cancer patients. Materials and Methods Patients who received PCRT and LE because of clinical T2 rectal cancer within 7 cm from anal verge between January 2006 and June 2014 were retrospectively analyzed. LE was performed in case of a good clinical response after PCRT. Patients’ characteristics, treatment record, tumor recurrence, and treatment-related complications were reviewed at a median follow-up of 49 months. Results All patients received transanal excision or transanal minimally invasive surgery. Of 34 patients, 19 patients (55.9%) presented pathologic complete response (pCR). The 3-year local recurrence-free survival and disease free-survival were 100.0% and 97.1%, respectively. There was no recurrence among the patients with pCR. Except for 1 case of grade 4 enterovesical fistula, all other late complications were mild and self-limiting. Conclusion PCRT followed by an LE might be feasible as an alternative to total mesorectal excision in good responders with clinical T2N0 distal rectal cancer. PMID:27730804

  7. Discussion of isomeric ratios in (p, n) and (d, 2 n) reaction

    NASA Astrophysics Data System (ADS)

    Bakhshiyan, T. M.

    2016-01-01

    Isomeric ratios (IR) in the (p, n) and (d, 2 n) reactions are considered. The dependence of IR values on the projectile type and energy, the target- and product-nucleus spin, the spin difference between the isomeric and ground states of products, and the product mass number is discussed. The isomeric ratios for 46 product nuclei (from 44m,gSc to 127m,gXe) obtained in reactions where target and product nuclei have identical mass numbers were calculated at energies from the reaction threshold to 50 MeV (with a step of Δ E = 1 MeV). The calculations in question were performed with the aid of the TALYS 1.4 code package. The calculated IR values were compared with their experimental counterparts available from the literature (EXFOR database). In the majority of cases, the calculated IR values agree well with the experimental data in question. It is noteworthy that the IR values obtained in (d, 2 n) reactions are substantially greater than those in (p, n) reactions.

  8. New data on ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) partial photoneutron reactions

    SciTech Connect

    Varlamov, V. V. Ishkhanov, B. S.; Orlin, V. N.; Peskov, N. N.; Stepanov, M. E.

    2013-11-15

    Systematic discrepancies between the results of various experiments devoted to determining cross sections for total and partial photoneutron reactions are analyzed by using objective criteria of reliability of data in terms of the transitional photoneutron-multiplicity function F{sub i} = {sigma}({gamma}, in)/{sigma}({gamma}, xn), whose values for i = 1, 2, 3, ... cannot exceed by definition 1.00, 0.50, 0.33, ..., respectively. It was found that the majority of experimental data on the cross sections obtained for ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) reactions with the aid of methods of photoneutron multiplicity sorting do not meet objective criteria (in particular, F{sub 2} > 0.50 for a vast body of data). New data on the cross sections for partial reactions on {sup 181}Ta and {sup 208}Pb nuclei were obtained within a new experimental-theoretical method that was proposed for the evaluation of cross sections for partial reactions and in which the experimental neutron yield cross section {sigma}{sup expt}({gamma}, xn) = {sigma}({gamma}, n) + 2{sigma}({gamma}, 2n) + 3{sigma}({gamma}, 3n) + ..., which is free from problems associated with determining neutron multiplicities, is used simultaneously with the functions F{sub i}{sup theor} calculated within a combined model of photonuclear reactions.

  9. Canonical formalism for a 2n-dimensional model with topological mass generation

    SciTech Connect

    Deguchi, Shinichi

    2008-12-15

    The four-dimensional model with topological mass generation that was found by Dvali, Jackiw, and Pi has recently been generalized to any even number of dimensions (2n dimensions) in a nontrivial manner in which a Stueckelberg-type mass term is introduced [S. Deguchi and S. Hayakawa, Phys. Rev. D 77, 045003 (2008)]. The present paper deals with a self-contained model, called here a modified hybrid model, proposed in this 2n-dimensional generalization and considers the canonical formalism for this model. For the sake of convenience, the canonical formalism itself is studied for a model equivalent to the modified hybrid model by following the recipe for treating constrained Hamiltonian systems. This formalism is applied to the canonical quantization of the equivalent model in order to clarify observable and unobservable particles in the model. The equivalent model (with a gauge-fixing term) is converted to the modified hybrid model (with a corresponding gauge-fixing term) in a Becchi-Rouet-Stora-Tyutin-invariant manner. Thereby it is shown that the Chern-Pontryagin density behaves as an observable massive particle (or field). The topological mass generation is thus verified at the quantum-theoretical level.

  10. Planet Formation

    NASA Astrophysics Data System (ADS)

    Klahr, Hubert; Brandner, Wolfgang

    2011-02-01

    1. Historical notes on planet formation Bodenheimer; 2. The formation and evolution of planetary systems Bouwman et al.; 3. Destruction of protoplanetary disks by photoevaporation Richling, Hollenbach and Yorke; 4. Turbulence in protoplanetary accretion disks Klahr, Rozyczka, Dziourkevitch, Wunsch and Johansen; 5. The origin of solids in the early solar system Trieloff and Palme; 6. Experiments on planetesimal formation Wurm and Blum; 7. Dust coagulation in protoplanetary disks Henning, Dullemond, Wolf and Dominik; 8. The accretion of giant planet cores Thommes and Duncan; 9. Planetary transits: direct vision of extrasolar planets Lecavelier des Etangs and Vidal-Madjar; 10. The core accretion - gas capture model Hubickyj; 11. Properties of exoplanets Marcy, Fischer, Butler and Vogt; 12. Giant planet formation: theories meet observations Boss; 13. From hot Jupiters to hot Neptures … and below Lovis, Mayor and Udry; 14. Disk-planet interaction and migration Masset and Kley; 15. The Brown Dwarf - planet relation Bate; 16. From astronomy to astrobiology Brandner; 17. Overview and prospective Lin.

  11. Heterogeneous oxidation kinetics of organic biomass burning aerosol surrogates by O3, NO2, N2O5, and NO3.

    PubMed

    Knopf, Daniel A; Forrester, Seanna M; Slade, Jonathan H

    2011-12-21

    The reactive uptake coefficients (γ) of O(3), NO(2), N(2)O(5), and NO(3) by levoglucosan, abietic acid, nitroguaiacol, and an atmospherically relevant mixture of those species serving as surrogates for biomass burning aerosol have been determined employing a chemical ionization mass spectrometer coupled to a rotating-wall flow-tube reactor. γ of O(3), NO(2), N(2)O(5), and NO(3) in the presence of O(2) are in the range of 1-8 × 10(-5), <10(-6)-5 × 10(-5), 4-6 × 10(-5), and 1-26 × 10(-3), respectively, for the investigated organic substrates. Within experimental uncertainties the uptake of NO(3) was not sensitive to the presence of water vapour ( <0.5% relative humidity). [corrected]. NO(3) uptake experiments involving substrates of levoglucosan, abietic acid, and the mixture exhibit an initial strong uptake of NO(3) followed by NO(3) gas-phase recovery as a function of NO(3) exposure. In contrast, the uptake of NO(3) by nitroguaiacol continuously proceeds at the same efficiency for investigated NO(3) exposures. The derived oxidative power, i.e. the product of γ and atmospheric oxidant concentration, for applied oxidants is similar or significantly larger in magnitude than for OH, emphasizing the potential importance of these oxidants for particle oxidation. Estimated atmospheric lifetimes for the topmost organic layer with respect to O(3), NO(2), N(2)O(5), and NO(3) oxidation for typical polluted conditions range between 1-112 min, indicating the potential for significant chemical transformation during atmospheric transport. The contact angles determined prior to, and after heterogeneous oxidation by NO(3), representative of 50 ppt for 1 day, do not decrease and thus do not indicate a significant increase in hygroscopicity with potential impacts on water uptake and cloud formation processes.

  12. Generation of novel metabolites of dietary linoleic acid (18:2n6) by guinea pig epidermis

    SciTech Connect

    Chapkin, R.S.; Ziboh, V.A.

    1986-03-05

    Although the authors have demonstrated the inability of rat and guinea pig (GP) skin enzyme preparations to desaturate 18:2n6 into gammalinolenic acid (18:3n6) using an in vitro microsomal system, the fate of this dietary essential fatty acid in the GP epidermis is unknown. To explore the fate of 18:2n6, intact tissue slices from GP epidermis were incubated with (1-/sup 14/C)18:2n6. After incubation, the extracted lipids were transesterified using methanolic-HCL. The fatty acid methyl esters were analyzed using a combination of (i) argentation TLC, scanned using a proportional TLC radioscanner, and (ii) reverse phase HPLC, equipped with a flow through radioscanner. The results indicate that the intact epidermis metabolized /sup 14/C-18:2n6 to a group of novel products more polar than 18:2n6. In subsequent experiments, /sup 14/C-18:2n6 was either incubated with the 800 xg supernatant, the 105,000 xg pellet or supernatant from GP epidermis. Metabolism of 18:2n6 by the high speed supernatant resulted in the generation of polar products with chromatographic properties of not greater than 2 double bonds. These results indicate that although the GP epidermis lacks the capacity to desaturate 18:2n6 to 18:3n6, it can convert dietary 18:2n6 into a group of novel polar metabolites via a cytosolic mediated process. The function of these metabolites in the GP integumentary system remains to be determined.

  13. The metallofullerene field-induced single-ion magnet HoSc2 N@C80.

    PubMed

    Dreiser, Jan; Westerström, Rasmus; Zhang, Yang; Popov, Alexey A; Dunsch, Lothar; Krämer, Karl; Liu, Shi-Xia; Decurtins, Silvio; Greber, Thomas

    2014-10-13

    The low-temperature magnetic properties of the endohedral metallofullerene HoSc2 N@C80 have been studied by superconducting quantum interference device (SQUID) magnetometry. Alternating current (ac) susceptibility measurements reveal that this molecule exhibits slow relaxation of magnetization in a small applied field with timescales in the order of milliseconds. The equilibrium magnetic properties of HoSc2 N@C80 indicate strong magnetic anisotropy. The large differences in magnetization relaxation times between the present compound and the previously investigated DySc2 N@C80 are discussed. PMID:25164532

  14. Helium Nanodroplet Isolation Spectroscopy and AB Initio Calculations of HO_3-(O_2)_N Clusters (N=0-4)

    NASA Astrophysics Data System (ADS)

    Liang, T.; Raston, P.; Douberly, G. E.

    2013-06-01

    The HOOO hydridotrioxygen radical and its deuterated analog (DOOO) have been isolated in helium nanodroplets following the in-situ association reaction between OH and O_2. The infrared spectrum in the 3500-3700 cm^{-1} region reveals bands that are assigned to the ν_1 (OH stretch) fundamental and ν_1+ν_6 (OH stretch plus torsion) combination band of the trans-HOOO isomer. The helium droplet spectrum is assigned on the basis of a detailed comparison to the infrared spectrum of HOOO produced in the gas phase [E. L. Derro, T. D. Sechler, C. Murray, and M. I. Lester, J. Chem. Phys. 128, 244313 (2008)]. Despite the characteristic low temperature and rapid cooling of helium nanodroplets, there is no evidence for the formation of a weakly bound OH-O_2 van der Waals complex, which implies the absence of a kinetically significant barrier in the entrance channel of the reaction. There is also no spectroscopic evidence for the formation of cis-HOOO, which is predicted by theory to be nearly isoenergetic to the trans isomer. Stark spectroscopy of the trans-HOOO species provides vibrationally averaged dipole moment components that qualitatively disagree with predictions obtained from CCSD(T) computations at the equilibrium, planar geometry, indicating a floppy complex undergoing large-amplitude motion about the torsional coordinate. Under conditions that favor the introduction of multiple O_2 molecules to the droplets, bands associated with larger H/DOOO-(O_2)_n clusters are observed shifted 1-10 cm^{-1} to the red of the trans-H/DOOO ν_1 bands. Detailed ab initio calculations are carried out for multiple isomers of cis- and trans-HO_3-O_2, corresponding to either hydrogen or oxygen bonded van der Waals complexes. Comparisons to theory suggest that the structure of the HO_3-O_2 complex formed in helium droplets is a hydrogen-bonded ^4A' species consisting of a trans-HO_3 core. The computed binding energy of the complex is approximately 240 cm^{-1}. Despite the weak

  15. Zygospore formation between homothallic and heterothallic strains of Closterium.

    PubMed

    Tsuchikane, Yuki; Tsuchiya, Miki; Hindák, František; Nozaki, Hisayoshi; Sekimoto, Hiroyuki

    2012-03-01

    Zygospore formation in different strains of the Closterium peracerosum-strigosum-littorale complex was examined in this unicellular isogamous charophycean alga to shed light on gametic mating strains in this taxon, which is believed to share a close phylogenetic relationship with land plants. Zygospores typically form as a result of conjugation between mating-type plus (mt(+)) and mating-type minus (mt(-)) cells during sexual reproduction in the heterothallic strain, similar to Chlamydomonas. However, within clonal cells, zygospores are formed within homothallic strains, and the majority of these zygospores originate as a result of conjugation of two recently divided sister gametangial cells derived from one vegetative cell. In this study, we analyzed conjugation of homothallic cells in the presence of phylogenetically closely related heterothallic cells to characterize the reproductive function of homothallic sister gametangial cells. The relative ratio of non-sister zygospores to sister zygospores increased in the presence of heterothallic mt(+) cells, compared with that in the homothallic strain alone and in a coculture with mt(-) cells. Heterothallic cells were surface labeled with calcofluor white, permitting fusions with homothallic cells to be identified and confirming the formation of hybrid zygospores between the homothallic cells and heterothallic mt(+) cells. These results show that at least some of the homothallic gametangial cells possess heterothallic mt(-)-like characters. This finding supports speculation that division of one vegetative cell into two sister gametangial cells is a segregative process capable of producing complementary mating types.

  16. Unipolar resistive switching with forming-free and self-rectifying effects in Cu/HfO2/n-Si devices

    NASA Astrophysics Data System (ADS)

    Wang, M. J.; Gao, S.; Zeng, F.; Song, C.; Pan, F.

    2016-02-01

    One of the most effective methods integrating self-rectifying RRAM is alleviating sneak current in crossbar architecture. In this work, to investigate RRAMs with excellent properties of self-rectifying effect, simple Cu/HfO2/n-Si tri-layer devices are fabricated and investigated through I - V characteristic measurement. The experimental results demonstrate that the device exhibits forming-free behavior and a remarkable rectifying effect in low resistance state (LRS) with rectification ratio of 104 at ±1 V, as well as considerable OFF/ON ratio (resistive switching window) of 104 at 1 V. The formation and annihilation of localized Cu conductive filament plays a key role in the resistive switching between low resistance state (LRS) and high resistance state (HRS). In addition, intrinsic rectifying effect in LRS attributes to the Schottky contact between Cu filament and n-Si electrode. Furthermore, satisfactory switching uniformity of cycles and devices is observed. As indicated by the results, Cu/HfO2/n-Si devices have a high potential for high-density storage practical application due to its excellent properties.

  17. Galaxy formation.

    PubMed

    Peebles, P J

    1998-01-01

    It is argued that within the standard Big Bang cosmological model the bulk of the mass of the luminous parts of the large galaxies likely had been assembled by redshift z approximately 10. Galaxy assembly this early would be difficult to fit in the widely discussed adiabatic cold dark matter model for structure formation, but it could agree with an isocurvature version in which the cold dark matter is the remnant of a massive scalar field frozen (or squeezed) from quantum fluctuations during inflation. The squeezed field fluctuations would be Gaussian with zero mean, and the distribution of the field mass therefore would be the square of a random Gaussian process. This offers a possibly interesting new direction for the numerical exploration of models for cosmic structure formation.

  18. Galaxy formation

    PubMed Central

    Peebles, P. J. E.

    1998-01-01

    It is argued that within the standard Big Bang cosmological model the bulk of the mass of the luminous parts of the large galaxies likely had been assembled by redshift z ∼ 10. Galaxy assembly this early would be difficult to fit in the widely discussed adiabatic cold dark matter model for structure formation, but it could agree with an isocurvature version in which the cold dark matter is the remnant of a massive scalar field frozen (or squeezed) from quantum fluctuations during inflation. The squeezed field fluctuations would be Gaussian with zero mean, and the distribution of the field mass therefore would be the square of a random Gaussian process. This offers a possibly interesting new direction for the numerical exploration of models for cosmic structure formation. PMID:9419326

  19. Modified non-Euclidean transformation on the SO(2N+2) U(N+1) Grassmannian and SO(2N + 1) random phase approximation for unified description of Bose and Fermi type collective excitations

    NASA Astrophysics Data System (ADS)

    Nishiyama, Seiya; da Providência, João

    2016-02-01

    In a slight different way from the previous one, we propose a modified non-Euclidean transformation on the SO(2N+2) U(N+1) Grassmannian which gives the projected SO(2N+1) Tamm-Dancoff equation. We derive a classical time-dependent (TD) SO(2N + 1) Lagrangian which, through the Euler-Lagrange equation of motion for SO(2N+2) U(N+1) coset variables, brings another form of the previous extended-TD Hartree-Bogoliubov (HB) equation. The SO(2N + 1) random phase approximation (RPA) is derived using Dyson representation for paired and unpaired operators. In the SO(2N) HB case, one boson and two boson excited states are realized. We, however, stress non-existence of a higher RPA vacuum. An integrable system is given by a geometrical concept of zero-curvature, i.e. integrability condition of connection on the corresponding Lie group. From the group theoretical viewpoint, we show the existence of a symplectic two-form ω.

  20. High-pressure Raman spectroscopy of perovskite oxynitride SrTaO2N

    NASA Astrophysics Data System (ADS)

    Son, Y.-G.; Jeong, I.-K.

    2016-09-01

    Perovskite oxynitrides exhibit emergent physical properties driven by a substitution of nitrogen for oxygen. The nitrogen substitution distorts the octahedra and induces octahedral tilting which are responsible for a relaxor-like temperature-insensitive dielectric response. To study the local structural evolution of oxynitride SrTaO2N under pressure, we performed in-situ high-pressure Raman spectroscopy measurements with a diamond anvil cell up to a pressure of P = 19 GPa. We find that forbidden modes were active, indicating a lowering of local symmetry from non-polar I4/mcm due to the octahedral distortion. Under pressure, a mode associated with TaO4N2 exhibits a negative wavenumber shift and merges with a nearby mode at a pressure of P ≃ 4.2 GPa. This result indicates a suppression of octahedral tilting under pressure.

  1. Measurement of the ^241Am(n,2n) Reaction Cross Section with the Activation Technique

    NASA Astrophysics Data System (ADS)

    Tonchev, A.; Crowell, A.; Fallin, B.; Howell, C.; Hutcheson, A.; Tornow, W.; Kelley, J.; Angell, C.; Karwowski, H.; Pedroni, R.; Becker, J.; Dashdorj, D.; Macri, R.; Wilhelmy, J.; Bond, E.; Fitzpatrick, J.; Slemmons, A.; Vieira, D.

    2006-10-01

    High-precision measurements of the ^241Am(n,2n)^240Am reaction have been performed with neutron energies from 8.8 to 14.0 MeV. The monoenergetic neutron beams were produced via the ^2H(d,n)^3He reaction using the 10 MV Tandem accelerator at TUNL. The radioactive targets consisted of 1mg highly-enriched ^241Am sandwiched between four different thin monitor foils. They were irradiated with a neutron flux of 3x10^7 n cm-2 s-1. After each irradiation the induced activity in the targets and monitors was measured off-line with 60% HPGe detectors. Our preliminary neutron induced cross sections will be compared with recent literature results and statistical model calculations using the GNASH and EMPIRE codes.

  2. Density functional theory study of MgnNi2 (n = 1-6) clusters

    NASA Astrophysics Data System (ADS)

    Li, Jing; Liu, Xiao-Yong; Zhu, Zheng-He; Sheng, Yong

    2012-03-01

    The geometries of MgnNi2(n = 1-6) clusters are studied by using the hybrid density functional theory (B3LYP) with LANL2DZ basis sets. For the ground-state structures of MgnNi2 clusters, the stabilities and the electronic properties are investigated. The results show that the groundstate structures and symmetries of Mg clusters change greatly due to the Ni atoms. The average binding energies have a growing tendency while the energy gaps have a declining tendency. In addition, the ionization energies exhibit an odd—even oscillation feature. We also conclude that n = 3, 5 are the magic numbers of the MgnNi2 clusters. The Mg3Ni2 and Mg5Ni2 clusters are more stable than neighbouring clusters, and the Mg4Ni2 cluster exhibits a higher chemical activity.

  3. Ab initio study of small Au nY 2 ( n=1-4) clusters

    NASA Astrophysics Data System (ADS)

    Jian-Jun, Guo; Ji-Xian, Yang; Dong, Die

    2008-11-01

    The geometries of the lowest-lying isomers of Au nY 2 ( n=1-4) clusters are determined systematically via the density functional method B3LYP with relativistic effective core potentials (RECP) and LANL2DZ basis set. Several low-lying isomers were determined, and many of them in electronic configurations with a high-spin multiplicity. The gold-yttrium interaction is strong enough to modify the known growth pattern of bare gold clusters. The stability trend of Y-doped Au n clusters is compared to that of pure Au n clusters. The results show that the inclusion of two Y atoms in the clusters improves the cluster stability, and indicate higher stability as the structures grow in size. The present calculations are useful to understand the enhanced catalytic activity and selectivity gained by using yttrium-doped gold catalyst.

  4. [Ca(BH4)2] n clusters as hydrogen storage material: A DFT study

    NASA Astrophysics Data System (ADS)

    Han, Cuiling; Dong, Yanyun; Wang, Bingqiang; Zhang, Caiyun

    2016-10-01

    Calcium borohydride is widely studied as a hydrogen storage material. However, investigations on calcium borohydride from a cluster perspective are seldom found. The geometric structures and binding energies of [Ca(BH4)2] n ( n = 1-4) clusters are determined using density function theory (DFT). For the most stable structures, vibration frequency, natural bond orbital (NBO) are calculated and discussed. The charge transfer from (BH4) to Ca was observed. Meanwhile, we also study the LUMO-HOMO gap ( E g) and the B-H bond dissociation energies (BDEs). [Ca(BH4)2]3 owns higher E g, revealing that trimer is more stable than the other forms. Structures don't change during optimization after hydrogen radical removal, showing that calcium borohydride could possibly be used as a reversible hydrogen storage material. [Ca(BH4)2]4 has the smallest dissociation energy suggesting it releases hydrogen more easily than others.

  5. Low-Temperature Reactivity of C2n+1N(-) Anions with Polar Molecules.

    PubMed

    Joalland, Baptiste; Jamal-Eddine, Nour; Kłos, Jacek; Lique, François; Trolez, Yann; Guillemin, Jean-Claude; Carles, Sophie; Biennier, Ludovic

    2016-08-01

    Following the recent discovery of molecular anions in the interstellar medium, we report on the kinetics of proton transfer reactions between cyanopolyynide anions C2n+1N(-) (n = 0, 1, 2) and formic acid HCOOH. The results, obtained from room temperature down to 36 K by means of uniform supersonic flows, show a surprisingly weak temperature dependence of the CN(-) reaction rate, in contrast with longer chain anions. The CN(-) + HCOOH reaction is further studied theoretically via a reduced dimensional quantum model that highlights a tendency of the reaction probability to decrease with temperature, in agreement with experimental data but at the opposite of conventional long-range capture theories. In return, comparing HCOOH to HC3N as target molecules suggests that dipole-dipole interactions must play an active role in overcoming this limiting effect at low temperatures. This work provides new fundamental insights on prototypical reactions between polar anions and polar molecules along with critical data for astrochemical modeling.

  6. Investigation of the 241Am(n ,2 n )240Am cross section

    NASA Astrophysics Data System (ADS)

    Kalamara, A.; Vlastou, R.; Kokkoris, M.; Diakaki, M.; Tsinganis, A.; Patronis, N.; Axiotis, M.; Lagoyannis, A.

    2016-01-01

    The 241Am(n ,2 n )240Am reaction cross section has been measured at four energies, 10.0, 10.4, 10.8, and 17.1 MeV, by means of the activation technique, relative to the 27Al(n ,α )24Na reaction reference cross section. Quasi-monoenergetic neutron beams were produced via the 2H(d ,n )3He and the 3H(d ,n )4He reactions at the 5.5 MV Tandem T11/25 accelerator laboratory of NCSR "Demokritos". The high purity 241Am targets were provided by JRC-IRMM, Geel, Belgium. The induced γ -ray activity of 240Am was measured with high-resolution high-purity germanium (HPGe) detectors. Auxiliary Monte Carlo simulations were performed with the mcnp code. The present results are in agreement with data obtained earlier and predictions obtained with the empire code.

  7. Enhanced CO2/N2 Selectivity in Amidoxime-Modified Porous Carbon

    SciTech Connect

    Mahurin, Shannon Mark; Gorka, Joanna; Nelson, Kimberly M; Mayes, Richard T; Dai, Sheng

    2014-01-01

    In this work, we examine the use of the amidoxime functional group grafted onto a hierarchical porous carbon framework for the selective capture and removal of carbon dioxide from combustion streams. Measured CO2/N2 ideal selectivity values for the amidoxime-grafted carbon were significantly higher than the pristine porous carbon with improvements of 65%. Though the overall CO2 capacity decreased slightly for the activated carbon from 4.97 mmol g-1 to 4.24 mmol g-1 after surface modification due to a reduction in the total surface area, the isosteric heats of adsorption increased after amidoxime incorporation indicating an increased interaction of CO2 with the sorbent. Total capacity was reproducible and stable after multiple adsorption/desorption cycles with no loss of capacity suggesting that modification with the amidoxime group is a potential method to enhance carbon capture.

  8. Symmetric Trajectories for the 2N-Body Problem with Equal Masses

    NASA Astrophysics Data System (ADS)

    Terracini, Susanna; Venturelli, Andrea

    2007-06-01

    We consider the problem of 2 N bodies of equal masses in mathbb{R}^3 for the Newtonian-like weak-force potential r -σ, and we prove the existence of a family of collision-free nonplanar and nonhomographic symmetric solutions that are periodic modulo rotations. In addition, the rotation number with respect to the vertical axis ranges in a suitable interval. These solutions have the hip-hop symmetry, a generalization of that introduced in [19], for the case of many bodies and taking account of a topological constraint. The argument exploits the variational structure of the problem, and is based on the minimization of Lagrangian action on a given class of paths.

  9. The lowest diploid number (2n = 16) yet found in any primate: Callicebus lugens (Humboldt, 1811).

    PubMed

    Bonvicino, Cibele R; Penna-Firme, Valéria; do Nascimento, Fabrícia F; Lemos, Bernardo; Stanyon, Roscoe; Seuánez, Héctor N

    2003-01-01

    Morphologic, molecular and karyologic analyses of Callicebus lugens (Humboldt, 1811) of known geographic origin supported the proposition that this is a valid species. Morphologic and morphometric analyses showed evident differences between C. lugens and two other related taxa of the same group (Callicebus purinus and Callicebus torquatus). Cytochrome b DNA analyses (maximum parsimony, neighbour joining and maximum likelihood) were congruent in showing a strong association between C. lugens and Callicebus sp. of the torquatus group in one branch and a sister branch further divided into two clades: one with species of the personatus group and another, with species of the moloch group. Karyotypic analysis showed that C. lugens has the lowest diploid chromosome number of the primate order (2n = 16). Comparisons with other congeneric species clearly supported the proposition that C. lugens is karyotypically similar to others of the torquatus group.

  10. The 239 Pu(n,2n)238Pu cross section: preliminary calculations

    SciTech Connect

    Chen, H; Reffo, G; Ross, M A; White, R M

    1999-03-12

    The primary motivation for the present work is to provide theoretical values for the ratio of the partial 239Pu(n,2nx{gamma})238Pu to total 239 Pu(n,2n)238Pu cross section for several discrete gamma transitions. Results and conclusions of preliminary calculations from threshold to 20 MeV are presented. Calculations are based on theoretical models with parameters obtained from the literature or from our ad hoc systematics. Optical model cross sections and transmission coefficients were determined using the coupled-channels method. The calculations included a preequilibrium component followed by multiple particle and gamma-ray emissions. Fission competition was included at all stages of de-excitation. Suggestions for further verifications and possible improvements are provided.

  11. Comparative study for elastic electron collisions on C{sub 2}N{sub 2} isomers

    SciTech Connect

    Michelin, S. E.; Falck, A. S.; Mazon, K. T.; Piacentini, J. J.; Scopel, M. A.; Silva, L. S. S. da; Oliveira, H. L.; Fujimoto, M. M.; Iga, I.; Lee, M.-T.

    2006-08-15

    In this work, we present a theoretical study on elastic electron collisions with the four C{sub 2}N{sub 2} isomers. More specifically, calculated differential, integral, and momentum transfer cross sections are reported in the 1-100 eV energy range. Calculations are performed at both the static-exchange-absorption and the static-exchange-polarization-absorption levels. The iterative Schwinger variational method combined with the distorted wave approximation is used to solve the scattering equations. Our study reveals an interesting trend of the calculated cross sections for the four isomers. In particular, strong isomer effect is seen at low incident energies. Also, we have identified a shape resonance which leads to a depression in the calculated partial integral cross section.

  12. Karyotyping of Brachypodium pinnatum (2n = 18) chromosomes using cross-species BAC-FISH.

    PubMed

    Wolny, Elzbieta; Fidyk, Wojciech; Hasterok, Robert

    2013-04-01

    Identification of individual chromosomes in a complement is usually a difficult task in the case of most plant species, especially for those with small, numerous, and morphologically uniform chromosomes. In this paper, we demonstrate that the landmarks produced by cross-species fluorescence in situ hybridisation (FISH) of Brachypodium distachyon derived bacterial artificial chromosome (BAC) clones can be used for discrimination of Brachypodium pinnatum (2n = 18) chromosomes. Selected sets of clones were hybridised in several sequential experiments performed on exactly the same chromosome spreads, using reprobing of cytological preparations. Analysis of the morphometric features of B. pinnatum chromosomes was performed to establish their total length, the position of centromeres, and the position of BAC-based landmarks in relation to the centromere, thereby enabling their effective karyotyping, which is a prerequisite for more complex study of the grass genome structure and evolution at the cytomolecular level. PMID:23706077

  13. Structural and electronic properties of B2N3 planar nanostructure: A computational investigation

    NASA Astrophysics Data System (ADS)

    Li, Jiao; Fan, Xinyu; Wei, Yanpei; Wang, Vei; Chen, Gang

    2016-09-01

    Using the systematic evolutionary structure searching method and the density functional theory, a new planar nanostructure composed of 5-6-8 rings referred as pho-B2N3 to stand for the penta-hexa-octa geometrical characters is proposed, which is dynamically stable due to the absence of imaginary mode in the calculated phonon spectrum. The thermal stability to withstand the temperature as high as 2000 K against melting and the mechanical stability to bear the strain as strong as 14.9% have also been proved. Furthermore, its band gap could be continuously tuned by strain between 0.38 and 2.13 eV, showing potential usage in field effect transistors.

  14. Effect of edge modification on the zigzag BC2N nanoribbons

    NASA Astrophysics Data System (ADS)

    Xiao, Xiang; Li, Hong; Tie, Jun; Lu, Jing

    2016-08-01

    We use first principles calculations to investigate the effects of edge modification with nonmetal species on zigzag-edged BC2N nanoribbons (ZBC2NNRs). These ZBC2NNRs show either semiconducting or metallic behaviors depending on the edge modifications and ribbon widths. We find that the O-modification induces a ferromagnetic ground state with a metallic behavior for all the ribbon widths investigated. And when the ribbon width is more than 3.32 nm (NZ ⩾ 16), an antiferromagnetic ground state with a half-metallic behavior is realized in the H-passivated ZBC2NNRs. These versatile electronic properties render the ZBC2NNRs a promising candidate material in nanoelectronics and nanospintronics.

  15. Infrared spectroscopy to probe structure and growth dynamics in Fe+-(CO2)n clusters

    NASA Astrophysics Data System (ADS)

    Gregoire, G.; Duncan, M. A.

    2002-08-01

    Fe+-(CO2)n ion-molecule complexes are produced by laser vaporization in a pulsed-nozzle cluster source. These species are analyzed and mass-selected using a specially designed reflectron time-of-flight mass spectrometer. Infrared photodissociation of these complexes is investigated with an optical parametric oscillator/amplifier system using wavelengths near the CO2 asymmetric stretch vibration (2349 cm-1). Dissociation occurs by successive elimination of CO2 molecules. Tunable laser experiments obtain infrared resonance-enhanced photodissociation spectra for these complexes. Small complexes have CO2 asymmetric stretch resonances shifted to higher frequency than the free CO2 mode. The blueshift decreases initially with cluster size, but becomes nearly constant after the n=4 cluster. Argon-tagged complexes, e.g., Fe+-(CO2)n[middle dot]Arm, photodissociate via the same CO2 resonances by elimination of argon. Except for the n=1 complex, bands for the tagged complexes occur at the same frequency as those for the corresponding CO2 complex without argon. Larger complexes exhibit additional resonances near the free CO2 asymmetric stretch indicating "surface" molecules not attached to the metal. Blueshifted resonances also persist in these complexes attributed to "core" ligands attached to the metal ion. In the largest clusters studied (n=9-14), additional resonances with an intermediate blueshift are measured associated with "caged" CO2 molecules not attached to the metal. These measurements demonstrate that infrared photodissociation spectroscopy has exciting potential to study clustering structures and dynamics around metal ions.

  16. Detection of Ketenimine (CH2CNH) in SGRB2(N) Hot Cores

    NASA Technical Reports Server (NTRS)

    Lovas, F. J.; Hollis, J. M.; Remijan, Anthony J.; Jewell, P. R.

    2006-01-01

    Ketenimine (CH2CNH) has been detected in absorption toward the starforming region Sagittarius B2(N) with the 100-m Green Bank Telescope (GBT) by means of three rotational transitions: 7(sub 16)-8(sub 08) at 41.5 GHz, 8(sub 19)-9(sub 09), at 23.2 GHz, and 9(sub 18)-10(sub 0,10) at 4.9 GHz. Ketenimine has a sparse rotational spectrum below 50 GHz. From transition line strength arguments, the spectral lines found are the ones most likely to be detected and occur in spectral regions that have little possibility of confusion with other molecular species. Partially resolved hyperfine structure is apparent in the 4.9 GHz transition which has energy levels approximately 50 K above ground state level; the absorption seen in this transition appears to be emanating from gas in close proximity to the LMH hot core that has a systemic LSR velocity of +64 kilometers per second. By comparison, the 41.5 GHz and 23.2 GHz transitions have lower energy levels of approximately 33 K and approximately 41 K, respectively; and show absorption against the two star-forming SgrB2(N) hot cores with systematic LSR velocities of +64 (the LMH) and +82 kilometers per second. These ketenimine data show that the hot core at +82 kilometers per second is cooler than the hot core at +64 kilometers per second. Ketenimine is likely formed directly from its isomer methyl cyanide (CH3CN) by tautomerization driven by shocks that pervade the star-forming region.

  17. Accurate ab initio Quartic Force Fields of Cyclic and Bent HC2N Isomers

    NASA Technical Reports Server (NTRS)

    Inostroza, Natalia; Huang, Xinchuan; Lee, Timothy J.

    2012-01-01

    Highly correlated ab initio quartic force field (QFFs) are used to calculate the equilibrium structures and predict the spectroscopic parameters of three HC2N isomers. Specifically, the ground state quasilinear triplet and the lowest cyclic and bent singlet isomers are included in the present study. Extensive treatment of correlation effects were included using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T). Dunning s correlation-consistent basis sets cc-pVXZ, X=3,4,5, were used, and a three-point formula for extrapolation to the one-particle basis set limit was used. Core-correlation and scalar relativistic corrections were also included to yield highly accurate QFFs. The QFFs were used together with second-order perturbation theory (with proper treatment of Fermi resonances) and variational methods to solve the nuclear Schr dinger equation. The quasilinear nature of the triplet isomer is problematic, and it is concluded that a QFF is not adequate to describe properly all of the fundamental vibrational frequencies and spectroscopic constants (though some constants not dependent on the bending motion are well reproduced by perturbation theory). On the other hand, this procedure (a QFF together with either perturbation theory or variational methods) leads to highly accurate fundamental vibrational frequencies and spectroscopic constants for the cyclic and bent singlet isomers of HC2N. All three isomers possess significant dipole moments, 3.05D, 3.06D, and 1.71D, for the quasilinear triplet, the cyclic singlet, and the bent singlet isomers, respectively. It is concluded that the spectroscopic constants determined for the cyclic and bent singlet isomers are the most accurate available, and it is hoped that these will be useful in the interpretation of high-resolution astronomical observations or laboratory experiments.

  18. α and 2 p 2 n emission in fast neutron-induced reactions on 60Ni

    NASA Astrophysics Data System (ADS)

    Fotiades, N.; Devlin, M.; Haight, R. C.; Nelson, R. O.; Kunieda, S.; Kawano, T.

    2015-06-01

    Background: The cross sections for populating the residual nucleus in the reaction ZAX(n,x) Z -2 A -4Y exhibit peaks as a function of incident neutron energy corresponding to the (n ,n'α ) reaction and, at higher energy, to the (n ,2 p 3 n ) reaction. The relative magnitudes of these peaks vary with the Z of the target nucleus. Purpose: Study fast neutron-induced reactions on 60Ni. Locate experimentally the nuclear charge region along the line of stability where the cross sections for α emission and for 2 p 2 n emission in fast neutron-induced reactions are comparable as a further test of reaction models. Methods: Data were taken by using the Germanium Array for Neutron-Induced Excitations. The broad-spectrum pulsed neutron beam of the Los Alamos Neutron Science Center's Weapons Neutron Research facility provided neutrons in the energy range from 1 to 250 MeV. The time-of-flight technique was used to determine the incident-neutron energies. Results: Absolute partial cross sections for production of seven discrete Fe γ rays populated in 60Ni (n ,α /2 p x n γ ) reactions with 2 ≤x ≤5 were measured for neutron energies 1 MeV2 n and 2 p 3 n emission at higher incident energies in the nuclear charge region around Fe.

  19. Germ cell formation from embryonic stem cells and the use of somatic cell nuclei in oocytes.

    PubMed

    Pelosi, Emanuele; Forabosco, Antonino; Schlessinger, David

    2011-03-01

    Embryonic stem cells (ESCs) have remarkable properties of pluripotency and self-renewal, along with the retention of chromosomal integrity. Germ cells function as a kind of "transgenerational stem cells," transmitting genetic information from one generation to the next. The formation of putative primordial germ cells (PGCs) and germ cells from mouse and human ESCs (hESCs) has, in fact, been shown, and the apparent derivation of functional mouse male gametes has also been described. Additionally, investigators have successfully reprogrammed somatic nuclei into a pluripotent state by inserting them into ESCs or oocytes. This would enable the generation of ESCs genetically identical to the somatic cell donor and their use in cell therapy. However, these methodologies are still inefficient and their mechanisms poorly understood. Until full comprehension of these processes is obtained, clinical applications remain remote. Nevertheless, they represent promising tools in the future, enhancing methods of therapeutic cloning and infertility treatment.

  20. Mouse Y-Encoded Transcription Factor Zfy2 Is Essential for Sperm Formation and Function in Assisted Fertilization

    PubMed Central

    Yamauchi, Yasuhiro; Riel, Jonathan M.; Ruthig, Victor; Ward, Monika A.

    2015-01-01

    Abstract Spermatogenesis is a key developmental process allowing for a formation of a mature male gamete. During its final phase, spermiogenesis, haploid round spermatids undergo cellular differentiation into spermatozoa, which involves extensive restructuring of cell morphology, DNA, and epigenome. Using mouse models with abrogated Y chromosome gene complements and Y-derived transgene we identified Y chromosome encoded Zfy2 as the gene responsible for sperm formation and function. In the presence of a Zfy2 transgene, mice lacking the Y chromosome and transgenic for two other Y-derived genes, Sry driving sex determination and Eif2s3y initiating spermatogenesis, are capable of producing sperm which when injected into the oocytes yield live offspring. Therefore, only three Y chromosome genes, Sry, Eif2s3y and Zfy2, constitute the minimum Y chromosome complement compatible with successful intracytoplasmic sperm injection in the mouse. PMID:26719889

  1. Synthesis, structure and properties of [Co(NCS)2(4-(4-chlorobenzyl)pyridine)2]n, that shows slow magnetic relaxations and a metamagnetic transition.

    PubMed

    Werner, Julia; Tomkowicz, Zbigniew; Rams, Michał; Ebbinghaus, Stefan G; Neumann, Tristan; Näther, Christian

    2015-08-21

    The reaction of Co(NCS)2 with 4-(4-chlorobenzyl)pyridine (ClBP) leads to the formation of Co(NCS)2(4-(4-chlorobenzyl)pyridine)4 () and [Co(NCS)2(4-(4-chlorobenzyl)pyridine)2]n (). In the crystal structure of the Co(ii) cations are octahedrally coordinated by two terminal bonded thiocyanato anions and four ClBP ligands, whereas in the Co(ii) cations are linked into chains by pairs of μ-1,3-bridging thiocyanato anions. Magnetic measurements of show an antiferromagnetic phase transition with TN = 3.9 K. A metamagnetic transition is observed at the critical magnetic field of 260 Oe. Magnetic relaxations in the zero field are consistent with single chain magnetic behavior. These results are compared with those obtained for similar compounds reported recently. PMID:26182402

  2. An experimental and theoretical study of the aluminium species present in mixtures of AlCl3 with the ionic liquids [BMP]Tf2N and [EMIm]Tf2N.

    PubMed

    Eiden, Philipp; Liu, Qunxian; Zein El Abedin, Sherif; Endres, Frank; Krossing, Ingo

    2009-01-01

    It is known that nano- or microcrystalline aluminium may be electrodeposited from mixtures of AlCl(3) and the ionic liquids 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([BMP]Tf(2)N) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf(2)N), and that two phases form with higher formal concentrations of AlCl(3) (at 1.6 mol L(-1) (x(Al)=0.33) and 2.5 mol L(-1) (x(Al)=0.39), respectively). This account analyzes the hitherto unknown molecular nature of these mixtures by a detailed experimental (multinuclear NMR and Raman spectroscopies) and theoretical study (BP86/TZVP DFT calculations, including COSMO solvation energies). The addition of AlCl(3) to the two liquids first leads to complexation with [Tf(2)N](-) and then disproportionation of the initial [AlCl(x)(Tf(2)N)(y)](-) complexes give Al(Tf(2)N)(3) and [AlCl(4)](-). At high concentrations of AlCl(3), the lower phase consists almost completely of Al(Tf(2)N)(3), whereas in the upper phase [AlCl(4)](-) is the dominant species. Electrodeposition of aluminium in the upper phase occurs from mixed AlCl(x)(Tf(2)N)(y) species, most likely from [AlCl(2)(Tf(2)N)(2)](-) formed in small concentrations at the phase boundary between the [AlCl(4)](-) and the Al(Tf(2)N)(3) layers. All the findings are supported by DFT calculations as well as an X-ray crystal structure determination of Al(Tf(2)N)(3). The latter was separated from the mixture by sublimation on a preparative scale. It was independently prepared from AlEt(3) and HNTf(2) and fully characterized. Moreover, the ionic liquids [BMP]AlCl(4) (m.p. 74 degrees C) and [EMIm]AlCl(4) (m.p. -7 degrees C), which mainly form the upper layer in the biphasic regime, were independently prepared and also fully characterized. PMID:19229940

  3. CO 2 and O 2/N 2 variations in and just below the bubble-clathrate transformation zone of Antarctic ice cores

    NASA Astrophysics Data System (ADS)

    Lüthi, Dieter; Bereiter, Bernhard; Stauffer, Bernhard; Winkler, Renato; Schwander, Jakob; Kindler, Philippe; Leuenberger, Markus; Kipfstuhl, Sepp; Capron, Emilie; Landais, Amaelle; Fischer, Hubertus; Stocker, Thomas F.

    2010-08-01

    CO 2 measurements on the EPICA (European Project for Ice Coring in Antarctica) DML ice core in depth levels just below the bubble ice-clathrate ice transformation zone (1230-2240 m depth) were performed. In the youngest part (1230-1600 m), they reveal variations of up to 25 ppmv around the mean atmospheric concentration within centimetres, corresponding to a snow deposition interval of a few years. Similar results are found at corresponding depth regions of the Dome C and the Talos Dome ice cores. Since we can exclude all hitherto known processes altering the concentration of CO 2 in ice cores, we present a hypothesis about spatial fractionation of air components related to episodically increasing clathrate formation followed by diffusion processes from bubbles to clathrates. This hypothesis is supported by optical line-scan observations and by O 2/N 2 measurements at the same depth where strong CO 2 variations are detected. Below the clathrate formation zone, this small-scale fractionation process is slowly smoothed out, most likely by diffusion, regaining the initial mean atmospheric concentration. Although this process compromises the representativeness of a single CO 2 measurement on small ice samples in the clathrate formation zone of an ice core, it does not affect the mean atmospheric CO 2 concentration if CO 2 values are averaged over a sufficiently long depth scale (> 10 cm in case of the EPICA DML ice core).

  4. Characterization of a novel reassortant influenza A virus (H2N2) from a domestic duck in Eastern China.

    PubMed

    Ma, Mai-Juan; Yang, Xiao-Xian; Qian, Yan-Hua; Zhao, Si-Yan; Hua, Sha; Wang, Tie-Cheng; Chen, Shan-Hui; Ma, Guang-Yuan; Sang, Xiao-Yu; Liu, Lin-Na; Wu, Ai-Ping; Jiang, Tai-Jiao; Gao, Yu-Wei; Gray, Gregory C; Zhao, Teng; Ling, Xia; Wang, Jing-Lin; Lu, Bing; Qian, Jun; Cao, Wu-Chun

    2014-12-23

    While H2N2 viruses have been sporadically isolated from wild and domestic birds, H2N2 viruses have not been detected among human populations since 1968. Should H2N2 viruses adapt to domestic poultry they may pose a risk of infection to people, as most anyone born after 1968 would likely be susceptible to their infection. We report the isolation of a novel influenza A virus (H2N2) cultured in 2013 from a healthy domestic duck at a live poultry market in Wuxi City, China. Sequence data revealed that the novel H2N2 virus was similar to Eurasian avian lineage avian influenza viruses, the virus had been circulating for ≥ two years among poultry, had an increase in α2,6 binding affinity, and was not highly pathogenic. Approximately 9% of 100 healthy chickens sampled from the same area had elevated antibodies against the H2 antigen. Fortunately, there was sparse serological evidence that the virus was infecting poultry workers or had adapted to infect other mammals. These findings suggest that a novel H2N2 virus has been circulating among domestic poultry in Wuxi City, China and has some has increased human receptor affinity. It seems wise to conduct better surveillance for novel influenza viruses at Chinese live bird markets.

  5. Amphiplex Formation

    NASA Astrophysics Data System (ADS)

    Petersen, Shannon; Laaser, Jennifer; Lodge, Timothy

    2015-03-01

    Polymer-micelle complexes are currently under heavy investigation due to their potential applications in targeted drug delivery and gene therapy, yet the dynamics of the complex formation is still relatively unstudied. By varying the ratios of poly(styrene sulfonate) chains and cationic poly(dimethylaminoethyl methacrylate)-b-poly(styrene) micelles and the ionic strength of the system, we created a variety of complex configurations of different sizes and charges. The complexes were characterized dynamic light scattering and zeta potential measurements which provided information regarding the hydrodynamic radius, distribution of sizes, and effective charge.

  6. Phenakite-type BeP2N4--a possible precursor for a new hard spinel-type material.

    PubMed

    Pucher, Florian J; Römer, S Rebecca; Karau, Friedrich W; Schnick, Wolfgang

    2010-06-25

    BeP(2)N(4) was synthesized in a multi-anvil apparatus starting from Be(3)N(2) and P(3)N(5) at 5 GPa and 1500 degrees C. The compound crystallizes in the phenakite structure type (space group R3, no. 148) with a=1269.45(2) pm, c=834.86(2) pm, V=1165.13(4) x 10(6) pm(3) and Z=18. As isostructural and isovalence-electronic alpha-Si(3)N(4) transforms into beta-Si(3)N(4) at high pressure and temperature, we studied the phase transition of BeP(2)N(4) into the spinel structure type by using density functional theory calculations. The predicted transition pressure of 24 GPa is within the reach of today's state of the art high-pressure experimental setups. Calculations of inverse spinel-type BeP(2)N(4) revealed this polymorph to be always higher in enthalpy than either phenakite-type or spinel-type BeP(2)N(4). The predicted bulk modulus of spinel-type BeP(2)N(4) is in the range of corundum and gamma-Si(3)N(4) and about 40 GPa higher than that of phenakite-type BeP(2)N(4). This finding implies an increase in hardness in analogy to that occurring for the beta- to gamma-Si(3)N(4) transition. In hypothetical spinel-type BeP(2)N(4) the coordination number of phosphorus is increased from 4 to 6. So far only coordination numbers up to 5 have been experimentally realized (gamma-P(3)N(5)), though a sixfold coordination for P has been predicted for hypothetic delta-P(3)N(5). We believe, our findings provide a strong incentive for further high-pressure experiments in the quest for novel hard materials with yet unprecedented structural motives.

  7. Measurement of (23)Na(n,2n) cross section in well-defined reactor spectra.

    PubMed

    Košťál, Michal; Švadlenková, Marie; Baroň, Petr; Milčák, Ján; Mareček, Martin; Uhlíř, Jan

    2016-05-01

    The present paper aims to compare the calculated and experimental reaction rates of (23)Na(n,2n)(22)Na in a well-defined reactor spectra of a special core assembled in the LR-0 reactor. The experimentally determined reaction rate, derived using gamma spectroscopy of irradiated NaF sample, is used for average cross section determination. The resulting value averaged in spectra is 0.91±0.02µb. This cross-section is important as it is included in International Reactor Dosimetry and Fusion File and is also relevant to the correct estimation of long-term activity of Na coolant in Sodium Fast Reactors. The calculations were performed with the MCNP6 code using ENDF/B-VII.0, JEFF-3.1, JEFF-3.2, JENDL-3.3, JENDL-4, ROSFOND-2010 and CENDL-3.1 nuclear data libraries. Generally the best C/E agreement, within 2%, was found using the ROSFOND-2010 data set, whereas the worst, as high as 40%, was found using the ENDF/B-VII.0.

  8. Superhalogens beget superhalogens: a case study of (BO2)n oligomers.

    PubMed

    Kandalam, Anil K; Kiran, Boggavarapu; Jena, P; Pietsch, S; Ganteför, G

    2015-10-28

    Superhalogens belong to a class of molecules that not only mimic the chemistry of halogen atoms but also possess electron affinities that are much larger than that of chlorine, the element with the highest electron affinity in the periodic table. Using BO2 as an example and the synergy between density functional theory-based calculations and photoelectron spectroscopy experiments we demonstrate another unusual property of superhalogens. Unlike halogens, whose ability to accept an electron falls upon dimerization, B2O4, the dimer of BO2, has an electron affinity larger than that of the BO2 building block. This ability of (BO2)2 and subsequent, higher oligomers (BO2)n (n = 3 and 4), to retain their superhalogen characteristics can be traced to the enhanced bonding interactions between oxygen and boron atoms and due to the delocalization of the charge of the extra-electron over the terminal oxygen atoms. These results open the door to the design and synthesis of a new class of metal-free highly negative ions with potential for novel applications. PMID:26394536

  9. Intramolecular pnicogen interactions in PHF-(CH2)(n)-PHF (n=2-6) systems.

    PubMed

    Sánchez-Sanz, Goar; Alkorta, Ibon; Trujillo, Cristina; Elguero, José

    2013-06-01

    A computational study of the intramolecular pnicogen bond in PHF-(CH2)n-PHF (n=2-6) systems was carried out. For each compound, two different conformations, (R,R) and (R,S), were considered on the basis of the chirality of the phosphine groups. The characteristics of the closed conformers, in which the pnicogen interaction occurs, were compared with those of the extended conformer. In several cases, the closed conformations are more stable than the extended conformations. The calculated interaction energies of the pnicogen contact, by means of isodesmic reactions, provide values between -3.4 and -26.0 kJ mol(-1). Atoms in molecules and electron localization function analysis of the electron density showed that the systems in the closed conformations with short P···P distances have a partial covalent character in this interaction. The calculated absolute chemical shieldings of the P atoms showed an exponential relationship with the P···P distance. In addition, a search in the Cambridge crystallographic database was carried out to detect those compounds with a potential intramolecular pnicogen bond in the solid phase.

  10. Measurement of (23)Na(n,2n) cross section in well-defined reactor spectra.

    PubMed

    Košťál, Michal; Švadlenková, Marie; Baroň, Petr; Milčák, Ján; Mareček, Martin; Uhlíř, Jan

    2016-05-01

    The present paper aims to compare the calculated and experimental reaction rates of (23)Na(n,2n)(22)Na in a well-defined reactor spectra of a special core assembled in the LR-0 reactor. The experimentally determined reaction rate, derived using gamma spectroscopy of irradiated NaF sample, is used for average cross section determination. The resulting value averaged in spectra is 0.91±0.02µb. This cross-section is important as it is included in International Reactor Dosimetry and Fusion File and is also relevant to the correct estimation of long-term activity of Na coolant in Sodium Fast Reactors. The calculations were performed with the MCNP6 code using ENDF/B-VII.0, JEFF-3.1, JEFF-3.2, JENDL-3.3, JENDL-4, ROSFOND-2010 and CENDL-3.1 nuclear data libraries. Generally the best C/E agreement, within 2%, was found using the ROSFOND-2010 data set, whereas the worst, as high as 40%, was found using the ENDF/B-VII.0. PMID:26894323

  11. Benzyl-Functionalized Room Temperature Ionic Liquids for CO2/N2 Separation

    SciTech Connect

    Mahurin, Shannon Mark; Dai, Thomas N; Yeary, Joshua S; Luo, Huimin; Dai, Sheng

    2011-01-01

    In this work, three classes of room temperature ionic liquids (RTILs), including imidazolium, pyridinium, and pyrrolidinium ionic liquids with a benzyl group appended to the cation, were synthesized and tested for their performance in separating CO{sub 2} and N{sub 2}. All RTILs contained the bis(trifluoromethylsulfonyl)imide anion, permitting us to distinguish the impact of the benzyl moiety attached to the cation on gas separation performance. In general, the attachment of the benzyl group increased the viscosity of the ionic liquid compared with the unfunctionalized analogs and decreased the CO{sub 2} permeability. However, all of the benzyl-modified ionic liquids exhibited enhanced CO{sub 2}/N{sub 2} selectivities compared with alkyl-based ionic liquids, with values ranging from 22.0 to 33.1. In addition, CO{sub 2} solubilities in the form of Henry's constants were also measured and compared with unfunctionalized analogs. Results of the membrane performance tests and CO{sub 2} solubility measurements demonstrate that the benzyl-functionalized RTILs have significant potential for use in the separation of carbon dioxide from combustion products.

  12. Complete Results from a Spectral-Line Survey of Sgr B2(N)

    NASA Astrophysics Data System (ADS)

    Halfen, DeWayne T.; Ziurys, Lucy M.

    2016-06-01

    A confusion-limited spectral line survey of the Galactic center molecular cloud Sgr B2(N) at 3, 2, and 1 mm (68 - 116, 130 - 172, and 210 - 280 GHz) using the Kitt Peak 12 m and the Submillimeter Telescope (SMT) of the Arizona Radio Observatory was recently completed. About 15,000 spectral lines were observed in the survey range. The data have been analyzed using two techniques. First, the rotational temperature diagram methods was used for each individual species. Second, an LTE code was used to model and ultimately fit the data to a set of parameters for each species, using a least squares approach. Seventy-four molecules are identified in the data, along with 81 isotopologue species. In addition, 26 excited vibrational states of the identified molecules were detected, as well as H and He recombination lines. Source and Galactic absorption lines are seen in several abundant species, as well as multiple maser lines of methanol and possibly SO_2.

  13. Hydrogen Dissociation in a H_2-N2 Pulsed DC Glow Discharge

    NASA Astrophysics Data System (ADS)

    Williamson, J. M.; Ganguly, B. N.

    1999-10-01

    The relative concentration of hydrogen atoms was measured in the afterglow of a parallel-plate, pulsed DC discharge by two-photon allowed, laser induced fluorescence (TALIF). The TALIF signal was measured, relative to pure H_2, in H2 - N2 gas mixtures at constant pressure (2.5 Torr) and current (250 mA) for different fractions of N2 (0 to 1). For short pulse durations, <= 10 μsec, the TALIF signal drops off almost linearly with H2 concentration suggesting H2 is dissociated primarily by direct electron impact. For longer discharge pulses, >= 500 μsec, there is an enhancement in the fractional dissociation that increases with N2 concentration in the gas mixture. By varying the discharge pulse duration from 10 μsec to 1.0 msec at constant current and gas pressure, the change in the hydrogen atom production by direct electron impact compared to heavy particle collision induced dissociation has been measured.

  14. Rotational Energy Transfer Cross Sections in N2-N2 Collisions

    NASA Technical Reports Server (NTRS)

    Huo, Winifred M.; Green, Sheldon; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    Rotational inelastic transitions of N2 have been studied in the coupled state (CS, also called centrifugal sudden) and infinite-order-sudden (IOS) approximations, using the N2-N2 rigid-rotor potential of van der Avoird et al. For benchmarking purposes, close coupling (CC) calculations have also been carried out over a limited energy range and for even j - even j collisions only. Both the CC and CS cross sections have been obtained with and without exchange symmetry, whereas exchange is neglected in the IOS calculations. The CS results track the CC cross sections rather well. At total energies between 113 to 219 cm(exp -1) the average deviation is 14%. The deviation decrease with increasing energy, indicating that the CS approximation can be used as a substitute at higher energies when the CC calculations become impractical. Comparison between the CS and IOS cross sections at the high energy end of the CS calculation, 500 - 680 cm(exp-1), shows significant differences between the two. In addition, the IOS results exhibits sensitivity to the amount of inelasticity and the results for large DELTA J transitions are subjected to bigger errors. At total energy 113 cm(exp -1) and above, the average deviation between state-to-state cross sections calculated with even and odd exchange symmetries is 1.5%.

  15. Equilibrium and kinetic analysis of CO2-N2 adsorption separation by concentration pulse chromatography.

    PubMed

    Li, Peiyuan; Tezel, F Handan

    2007-09-01

    CO2 and N(2) adsorption kinetics and equilibrium behaviours have been studied with silicalite, NaY and 13X by using concentration pulse chromatography for the separation of these gases in the present study. Adsorption Henry's Law constants, the heat of adsorption values, micropore diffusion coefficients and corresponding activation energies are determined experimentally and the three different mass transfer mechanisms are discussed. From the equilibrium data, the corresponding separation factors are obtained for the adsorption separation processes. The heat of adsorption values as well as the Henry's Law adsorption equilibrium constants of CO(2) are much higher than those of N(2) for all the adsorbents studied. 13X, NaY and silicalite all have good separation factors for CO(2)/N(2) system based on equilibrium processes. The order of the equilibrium separation factors is 13X (Ceca)>13X (Zeochem)>NaY (UOP)>silicalite (UOP). Equilibrium selectivity favours CO(2) over N(2). Micropore diffusion resistance is the definite dominant mass transfer mechanism for CO(2) with silicalite and NaY.

  16. Superhalogens beget superhalogens: a case study of (BO2)n oligomers.

    PubMed

    Kandalam, Anil K; Kiran, Boggavarapu; Jena, P; Pietsch, S; Ganteför, G

    2015-10-28

    Superhalogens belong to a class of molecules that not only mimic the chemistry of halogen atoms but also possess electron affinities that are much larger than that of chlorine, the element with the highest electron affinity in the periodic table. Using BO2 as an example and the synergy between density functional theory-based calculations and photoelectron spectroscopy experiments we demonstrate another unusual property of superhalogens. Unlike halogens, whose ability to accept an electron falls upon dimerization, B2O4, the dimer of BO2, has an electron affinity larger than that of the BO2 building block. This ability of (BO2)2 and subsequent, higher oligomers (BO2)n (n = 3 and 4), to retain their superhalogen characteristics can be traced to the enhanced bonding interactions between oxygen and boron atoms and due to the delocalization of the charge of the extra-electron over the terminal oxygen atoms. These results open the door to the design and synthesis of a new class of metal-free highly negative ions with potential for novel applications.

  17. Mitosis and Interphase of the Highly Polyploid Palm Voanioalagerardii (2n = 606 ± 3).

    PubMed

    Röser, Martin

    2015-01-01

    The endemic, highly polyploid, monotypic Madagascan palm genus Voanioala (2n ≈ 606) was studied with regard to mitotic stages and interphase. Features of the cell cycle, morphology and sizes of metaphase chromosomes, fluorochrome banding patterns, and silver staining of NORs of such an extremely high polyploid organism are reported for the first time. On a whole, karyokinesis appears to be stable and efficient. A comparison with closely related palm taxa reveals that V. gerardii is 38-ploid, and comparison with the closely related genera Butia, Cocos (coconut) and Jubaea shows that Voanioala has lost ∼ 35% of its DNA amount subsequent to polyploidization and has suppressed between 74 and 88% of the original nucleolar organizers. About 10 active NORs are present in the nuclei. An auto- or allopolyploid origin of Voanioala is discussed with respect to currently available nuclear gene data. The biogeographic relations to Jubaeopsis, a closely related, monotypic, apparently likewise relict palm genus from eastern mainland South Africa are discussed. From a cytogenetic point of view, a common polyploid ancestor of both genera is most likely, but the available molecular phylogenetic data are not univocal. PMID:26594788

  18. The Effects of Flame Structure on Extinction of CH4-O2-N2 Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Du, J.; Axelbaum, R. L.; Gokoglu, S. (Technical Monitor)

    1996-01-01

    The effects of flame structure on the extinction limits of CH4-O2-N2 counterflow diffusion flames were investigated experimentally and numerically by varying the stoichiometric mixture fraction Z(sub st), Z(sub st) was varied by varying free-stream concentrations, while the adiabatic flame temperature T(sub ad) was held fixed by maintaining a fixed amount of nitrogen at the flame. Z(sub st) was varied between 0.055 (methane-air flame) and 0.78 (diluted- methane-oxygen flame). The experimental results yielded an extinction strain rate K(sub ext) of 375/s for the methane-air flame, increasing monotonically to 1042/s for the diluted-methane-oxygen flame. Numerical results with a 58-step Cl mechanism yielded 494/s and 1488/s, respectively. The increase in K(sub ext) with Z(sub st) for a fixed T(sub ad) is explained by the shift in the O2 profile toward the region of maximum temperature and the subsequent increase in rates for chain-branching reactions. The flame temperature at extinction reached a minimum at Z(sub st) = 0.65, where it was 200 C lower than that of the methane-air flame. This significant increase in resistance to extinction is seen to correspond to the condition in which the OH and O production zones are centered on the location of maximum temperature.

  19. Low-Temperature Reactivity of C2n+1N(-) Anions with Polar Molecules.

    PubMed

    Joalland, Baptiste; Jamal-Eddine, Nour; Kłos, Jacek; Lique, François; Trolez, Yann; Guillemin, Jean-Claude; Carles, Sophie; Biennier, Ludovic

    2016-08-01

    Following the recent discovery of molecular anions in the interstellar medium, we report on the kinetics of proton transfer reactions between cyanopolyynide anions C2n+1N(-) (n = 0, 1, 2) and formic acid HCOOH. The results, obtained from room temperature down to 36 K by means of uniform supersonic flows, show a surprisingly weak temperature dependence of the CN(-) reaction rate, in contrast with longer chain anions. The CN(-) + HCOOH reaction is further studied theoretically via a reduced dimensional quantum model that highlights a tendency of the reaction probability to decrease with temperature, in agreement with experimental data but at the opposite of conventional long-range capture theories. In return, comparing HCOOH to HC3N as target molecules suggests that dipole-dipole interactions must play an active role in overcoming this limiting effect at low temperatures. This work provides new fundamental insights on prototypical reactions between polar anions and polar molecules along with critical data for astrochemical modeling. PMID:27399038

  20. Scattered and (n,2n) neutrons as a measure of areal density in ICF capsules

    NASA Astrophysics Data System (ADS)

    Wilson, D. C.; Murphy, T. J.; Mead, W. C.; Disdier, L.; Houry, M.; Bayer, C.; Bourgade, J.-L.

    2001-10-01

    The fraction of low energy neutrons created from 14 MeV neutrons by elastic scattering and (n,2n) reactions on D and T can measure the areal density ρ r ( radial integral of density) of ICF targets. This may be crucial since for ignition capsules the fraction of reaction-in-flight neutrons is proportional to ρ r T and not simply ρ r^2 In simple situations the fraction of neutrons between 9.4 (the upper energy of T+T neutrons) and 13 MeV (below the Doppler broadened 14.1 MeV peak) is proportional to the ρ r at the time of neutron production. The ratio of neutrons at a specific energy (e.g. 13 MeV) to the their integral over all energies can be measured along different lines of sight. Because scattering is forward peaked, comparing these ratios provides a nearly linear measure of implosion asymmetry. Gamma rays can be a negligible background if the detector is placed inside the target chamber close enough to the target that measurements are made before the 14 MeV neutrons reach the chamber wall. Calculated gamma ray and scattered neutron backgrounds from a cryogenic target support or a diagnostic instrument do not pose a problem. A GaAs detector 2.5m from the target in the NIF chamber appears to have enough sensitivity and sufficiently rapid time response to make this measurement.

  1. Mott insulating states and quantum phase transitions of correlated SU(2 N ) Dirac fermions

    NASA Astrophysics Data System (ADS)

    Zhou, Zhichao; Wang, Da; Meng, Zi Yang; Wang, Yu; Wu, Congjun

    2016-06-01

    The interplay between charge and spin degrees of freedom in strongly correlated fermionic systems, in particular of Dirac fermions, is a long-standing problem in condensed matter physics. We investigate the competing orders in the half-filled SU (2 N ) Hubbard model on a honeycomb lattice, which can be accurately realized in optical lattices with ultracold large-spin alkaline-earth fermions. Employing large-scale projector determinant quantum Monte Carlo simulations, we have explored quantum phase transitions from the gapless Dirac semimetals to the gapped Mott insulating phases in the SU(4) and SU(6) cases. Both of these Mott insulating states are found to be columnar valence bond solid (cVBS) and to be absent of the antiferromagnetic Néel ordering and the loop current ordering. Inside the cVBS phases, the dimer ordering is enhanced by increasing fermion components and behaves nonmonotonically as the interaction strength increases. Although the transitions generally should be of first order due to a cubic invariance possessed by the cVBS order, the coupling to gapless Dirac fermions can soften the transitions to second order through a nonanalytic term in the free energy. Our simulations provide important guidance for the experimental explorations of novel states of matter with ultracold alkaline-earth fermions.

  2. Transported PDF Modeling of Nonpremixed Turbulent CO/H-2/N-2 Jet Flames

    SciTech Connect

    Zhao, xinyu; Haworth, D. C.; Huckaby, E. David

    2012-01-01

    Turbulent CO/H{sub 2}/N{sub 2} (“syngas”) flames are simulated using a transported composition probability density function (PDF) method. A consistent hybrid Lagrangian particle/Eulerian mesh algorithm is used to solve the modeled PDF transport equation. The model includes standard k–ϵ turbulence, gradient transport for scalars, and Euclidean minimum spanning tree (EMST) mixing. Sensitivities of model results to variations in the turbulence model, the treatment of radiation heat transfer, the choice of chemical mechanism, and the PDF mixing model are explored. A baseline model reproduces the measured mean and rms temperature, major species, and minor species profiles reasonably well, and captures the scaling that is observed in the experiments. Both our results and the literature suggest that further improvements can be realized with adjustments in the turbulence model, the radiation heat transfer model, and the chemical mechanism. Although radiation effects are relatively small in these flames, consideration of radiation is important for accurate NO prediction. Chemical mechanisms that have been developed specifically for fuels with high concentrations of CO and H{sub 2} perform better than a methane mechanism that was not designed for this purpose. It is important to account explicitly for turbulence–chemistry interactions, although the details of the mixing model do not make a large difference in the results, within reasonable limits.

  3. Habit formation

    PubMed Central

    Smith, Kyle S.; Graybiel, Ann M.

    2016-01-01

    Habits, both good ones and bad ones, are pervasive in animal behavior. Important frameworks have been developed to understand habits through psychological and neurobiological studies. This work has given us a rich understanding of brain networks that promote habits, and has also helped us to understand what constitutes a habitual behavior as opposed to a behavior that is more flexible and prospective. Mounting evidence from studies using neural recording methods suggests that habit formation is not a simple process. We review this evidence and take the position that habits could be sculpted from multiple dissociable changes in neural activity. These changes occur across multiple brain regions and even within single brain regions. This strategy of classifying components of a habit based on different brain signals provides a potentially useful new way to conceive of disorders that involve overly fixed behaviors as arising from different potential dysfunctions within the brain's habit network. PMID:27069378

  4. Habit formation.

    PubMed

    Smith, Kyle S; Graybiel, Ann M

    2016-03-01

    Habits, both good ones and bad ones, are pervasive in animal behavior. Important frameworks have been developed to understand habits through psychological and neurobiological studies. This work has given us a rich understanding of brain networks that promote habits, and has also helped us to understand what constitutes a habitual behavior as opposed to a behavior that is more flexible and prospective. Mounting evidence from studies using neural recording methods suggests that habit formation is not a simple process. We review this evidence and take the position that habits could be sculpted from multiple dissociable changes in neural activity. These changes occur across multiple brain regions and even within single brain regions. This strategy of classifying components of a habit based on different brain signals provides a potentially useful new way to conceive of disorders that involve overly fixed behaviors as arising from different potential dysfunctions within the brain's habit network.

  5. New yttrium evaluated cross sections and impact on 88-Y(n,2n)87-Y radchem

    SciTech Connect

    White, M; Kawano, T; Fotiadis, N; Devlin, M; Nelson, R; Garrett, P; Chadwick, M B; Becker, J A

    2004-03-04

    We evaluate new n+{sup 89}Y radchem cross sections using recent LANSCE/GEANIE measurements and GNASH nuclear model calculations, together with previous measurements at Livermore by Dietrich et al. A quantification of margins and uncertainties (QMU) analysis leads to evaluated cross sections for the (n,2n) population of the {sup 88}Y ground state and m1, m2 isomers, together with uncertainties. Our new results agree with historic radchem database cross sections within a few percent below 15 MeV (with larger differences above 15 MeV) and they therefore provide a validation of the historic Arthur work that is used in LANL simulation codes. Since the (n,2n) cross sections to the {sup 88}Y g.s. and m1, m2 isomers impact the average {sup 88}Y(n,2n){sup 87}Y cross section at leading-order, we determine the new 14.1 MeV average {sup 88}Y(n,2n){sup 87}Y cross section (crucially important for radchem). Our new 14 MeV average {sup 88}Y(n,2n){sup 87}Y cross section is 1107 mb ({+-} 4%) which agrees with the value obtained from the historic Arthur cross section data to 0.7%.

  6. Simultaneous and time-resolved temperature and relative CO2-N2 and O2-CO2-N2 concentration measurements with pure rotational coherent anti-Stokes Raman scattering for pressures as great as 5 MPa

    SciTech Connect

    Schenk, Martin; Seeger, Thomas; Leipertz, Alfred

    2005-09-10

    Pure rotational coherent anti-Stokes Raman-scattering (CARS) measurements have been performed in binary CO2-N2 and ternary CO2-O2-N2 mixtures in a temperature range between 300 and 773 K and pressures from 0.1 to 5 MPa to prove its potential for simultaneous single-shot thermometry and multispecies concentration measurements. In pressurized systems the CO2 component has a strong spectral influence on the pure rotational CARS spectra. Because of this dominance, pure rotational CARS proves to be a sensitive tool to measure in high-pressure combustion systems and the relative CO2-N2 concentration in the lower temperature range simultaneously with the temperature and the relative O2-N2 concentration. The evaluation of the spectra utilized a least-sum-squared differences fit of the spectral shape, weighted either constantly or inversely with respect to the normalized signal intensity. The results of the simultaneous temperature and relative CO2-N2 and O2-CO2-N2 concentration measurements provided a good accuracy and precision both in temperature and in concentrations. Because of the strong increase in the relative spectral contribution of CO2 with rising pressure, the precision of the CO2 concentration determination is in general significantly improved toward higher pressures, thus also clearly enhancing the CO2 detectability. The influence of temperature, O2 and CO2 concentration, pressure, and the evaluation techniques employed on both the accuracy and the precision is explained as well as their cross dependencies. The influence and limitations of the approximations used to model the CO2 molecule are discussed.

  7. First Principles Study of a-U2N3 Surfaces and its Anti-oxidant Mechanism

    NASA Astrophysics Data System (ADS)

    Jin, Mengting; Zhang, Yanning

    With the advantages over oxides as fuel materials for fast nuclear reactors, actinide nitrides have been extensively studied in experiments. In particular, a-U2N3 is also the main composition of surface layer obtained by surface nitriding for the enhancement of oxidation resistance of uranium in ambient conditions.[1-4] However, the anti-oxidant mechanism behind is still unclear, which hinders the further development of surface treatment technologies for uranium. Here we perform extensive ab initio studies on the geometric, magnetic and electronic properties of a-U2N3 bulk and (001) surfaces. Then the adsorption and diffusion of O2 near the stable a-U2N3(001) surface will be discussed, focusing on the local atomic arrangements of U-N and U-N-O that cannot be observed easily in experiments. Our theoretical results may give some insights in understanding the anti-oxidant mechanism of surface nitriding.

  8. Three-phase liquid-liquid-vapor equilibria behavior of certain binary CO/sub 2/-n-paraffin systems

    SciTech Connect

    Hottovy, J.D.; Kohn, J.P.; Luks, K.D.

    1981-07-01

    The 3-phase liquid-liquid-vapor loci of 4 binary CO/sub 2/-n-paraffin systems (n-dodecane, n-tridecane, n-tetradecane, n-pentadecane) are studied, and temperature, pressure, and molar volumes and composition of both liquid phases are reported. It is within this group of n-paraffins that the nature of the upper critical end point for the CO/sub 2/-containing binary systems changes with increasing carbon number from an upper critical solution (temperature) point where L/sub 1/ and L/sub 2/ phases become critical in presence of vapor phase to a K point, where L/sub 2/ and vapor phases become critical in the presence of L/sub 1/ phase. These 4 loci are compared with earlier obtained loci on CO/sub 2/-n-decane and CO/sub 2/-n-elcosane.

  9. Spectroscopic analysis of diphosphatriazolate anion (P2N3-) by coupled-cluster methods as a step toward N5-

    NASA Astrophysics Data System (ADS)

    Jin, Yifan; Perera, Ajith; Bartlett, Rodney J.

    2015-11-01

    The long sought N5- is a step from the recently synthesized aromatic pentagonal diphosphatriazolate anion (P2N3-). As accurate spectroscopic properties of N5- are only known from theoretical calculations, this manuscript demonstrates the accuracy of the computed P2N3- spectra (IR, Raman, and NMR) obtained from coupled-cluster methods [CCSD or CCSD(T)] compared to experiment, eliminating any ambiguities of the prior density functional theory (DFT) results. Excited and ionized state calculations from EOM-CCSD(T) and IP-EOM-CCSD offer predictions of those additional properties. Differences between P2N3- and N5- arise primarily due to the positive electron affinities of P2, which cause very different potential energy surfaces.

  10. Evaluation of CO2, N2 and He as Fire Suppression Agents in Microgravity

    NASA Technical Reports Server (NTRS)

    Ruff, Gary A.; Hicks, Michael; Pettegrew, Richard

    2004-01-01

    The U.S. modules of the International Space Station use gaseous CO2 as the fire extinguishing agent. This was selected as a result of extensive experience with CO2 as a fire suppressant in terrestrial applications, trade studies on various suppressants, and experiments. The selection of fire suppressants and suppression strategies for NASA s Lunar and Martian exploration missions will be based on the same studies and normal-gravity data unless reduced gravity fire suppression data is obtained. In this study, the suppressant agent concentrations required to extinguish a flame in low velocity convective flows within the 20-sec of low gravity on the KC-135 aircraft were investigated. Suppressant gas mixtures of CO2, N2, and He with the balance being oxygen/nitrogen mixtures with either 21% or 25% O2 were used to suppress flames on a 19-mm diameter PMMA cylinder in reduced gravity. For each of the suppressant mixtures, limiting concentrations were established that would extinguish the flame at any velocity. Similarly, concentrations were established that would not extinguish the flame. The limiting concentrations were generally consistent with previous studies but did suggest that geometry had an effect on the limiting conditions. Between the extinction and non-extinction limits, the suppression characteristics depended on the extinguishing agent, flow velocity, and O2 concentration. The limiting velocity data from the CO2, He, and N2 suppressants were well correlated using an effective mixture enthalpy per mole of O2, indicating that all act via O2 displacement and cooling mechanisms. In reduced gravity, the agent concentration required to suppress the flames increased as the velocity increased, up to approximately 10 cm/s (the maximum velocity evaluated in this experiment). The effective enthalpy required to extinguish flames at velocities of 10 cm/s is approximately the same as the concentrations in normal gravity. A computational study is underway to further

  11. SI2N overview paper: ozone profile measurements: techniques, uncertainties and availability

    NASA Astrophysics Data System (ADS)

    Hassler, B.; Petropavlovskikh, I.; Staehelin, J.; August, T.; Bhartia, P. K.; Clerbaux, C.; Degenstein, D.; De Mazière, M.; Dinelli, B. M.; Dudhia, A.; Dufour, G.; Frith, S. M.; Froidevaux, L.; Godin-Beekmann, S.; Granville, J.; Harris, N. R. P.; Hoppel, K.; Hubert, D.; Kasai, Y.; Kurylo, M. J.; Kyrölä, E.; Lambert, J.-C.; Levelt, P. F.; McElroy, C. T.; McPeters, R. D.; Munro, R.; Nakajima, H.; Parrish, A.; Raspollini, P.; Remsberg, E. E.; Rosenlof, K. H.; Rozanov, A.; Sano, T.; Sasano, Y.; Shiotani, M.; Smit, H. G. J.; Stiller, G.; Tamminen, J.; Tarasick, D. W.; Urban, J.; van der A, R. J.; Veefkind, J. P.; Vigouroux, C.; von Clarmann, T.; von Savigny, C.; Walker, K. A.; Weber, M.; Wild, J.; Zawodny, J.

    2013-11-01

    Peak stratospheric chlorofluorocarbon (CFC) and other ozone depleting substance (ODS) concentrations were reached in the mid to late 1990s. Detection and attribution of the expected recovery of the stratospheric ozone layer in an atmosphere with reduced ODSs as well as efforts to understand the evolution of stratospheric ozone in the presence of increasing greenhouse gases are key current research topics. These require a critical examination of the ozone changes with an accurate knowledge of the spatial (geographical and vertical) and temporal ozone response. For such an examination, it is vital that the quality of the measurements used be as high as possible and measurement uncertainties well quantified. In preparation for the 2014 United Nations Environment Programme (UNEP)/World Meteorological Organization (WMO) Scientific Assessment of Ozone Depletion, the SPARC/IO3C/IGACO-O3/NDACC (SI2N) initiative was designed to study and document changes in the global ozone profile distribution. This requires assessing long-term ozone profile data sets in regards to measurement stability and uncertainty characteristics. The ultimate goal is to establish suitability for estimating long-term ozone trends to contribute to ozone recovery studies. Some of the data sets have been improved as part of this initiative with updated versions now available. This summary presents an overview of stratospheric ozone profile measurement data sets (ground- and satellite-based) available for ozone recovery studies. Here we document measurement techniques, spatial and temporal coverage, vertical resolution, native units and measurement uncertainties. In addition, the latest data versions are briefly described (including data version updates as well as detailing multiple retrievals when available for a given satellite instrument). Archive location information is for each data set is also given.

  12. Total Cross Section Measurements and Velocity Distributions of Hyperthermal Charge Transfer in Xe2+ + N2

    NASA Astrophysics Data System (ADS)

    Hause, Michael; Prince, Benjamin; Bemish, Raymond

    Guided-ion beam measurements of the charge exchange (CEX) cross section for Xe2+ + N2 are reported for collision energies ranging from 0.3 to 100 eV in the center-of-mass frame. Measured total XS decrease from 69.5 +/-0.3 Angstroms2 (Angs.) at the lowest collision energies to 40 Angs.2at 100 eV. The product N2+CEX cross section is similar to the total CEX cross section while those of the dissociative product, N+, are less than 1Angs.2 for collision energies above 9 eV. The product N2+CEXcross section measured here are much larger than the total optical emission-excitation cross sections for the N2+(A) and (B) state products determined previously in the chemiluminescence study of Prince and Chiu suggesting that most of the N2+products are in the X state. Time-of-flight (TOF) spectra of both the Xe+ and N2+products suggest two different CEX product channels. The first leaves highly-vibrationally excited N2+products with forward scattered Xe+ (LAB frame) and releases between 0.35 to 0.6 eV translational energy for collisions below 17.6 eV. The second component decreases with collisional energy and leaves backscattered Xe+ and low-vibrational states of N2+.At collision energies above 17.6 eV, only charge exchange involving minimal momentum exchange remains in the TOF spectra. AFOSR 13RV07COR.

  13. Cadherin2 (N-cadherin) plays an essential role in zebrafish cardiovascular development

    PubMed Central

    Bagatto, Brian; Francl, Jessie; Liu, Bei; Liu, Qin

    2006-01-01

    Background Cadherins are cell surface adhesion molecules that play important roles in development of vertebrate tissues and organs. We studied cadherin2 expression in developing zebrafish heart using in situ hybridization and immunocytochemical methods, and we found that cadherin2 was strongly expressed by the myocardium of the embryonic zebrafish. To gain insight into cadherin2 role in the formation and function of the heart, we analyzed cardiac differentiation and performance in a cadherin2 mutant, glass onion (glo). Results We found that the cadherin2 mutant had enlarged pericardial cavity, disorganized atrium and ventricle, and reduced expression of a ventricular specific marker vmhc. Individual myocardiocytes in the glo mutant embryos became round shaped and loosely aggregated. In vivo measurements of cardiac performance revealed that the mutant heart had significantly reduced heart rate, stroke volume and cardiac output compared to control embryos. Formation of the embryonic vascular system in the glo mutants was also affected. Conclusion Our results suggest that cadherin2 plays an essential role in zebrafish cardiovascular development. Although the exact mechanisms remain unknown as to the formation of the enlarged pericardium and reduced peripheral blood flow, it is clear that myocardiocyte differentiation and physiological cardiovascular performance is impaired when cadherin2 function is disrupted. PMID:16719917

  14. Pattern Formation

    NASA Astrophysics Data System (ADS)

    Hoyle, Rebecca

    2006-03-01

    From the stripes of a zebra and the spots on a leopard's back to the ripples on a sandy beach or desert dune, regular patterns arise everywhere in nature. The appearance and evolution of these phenomena has been a focus of recent research activity across several disciplines. This book provides an introduction to the range of mathematical theory and methods used to analyse and explain these often intricate and beautiful patterns. Bringing together several different approaches, from group theoretic methods to envelope equations and theory of patterns in large-aspect ratio-systems, the book also provides insight behind the selection of one pattern over another. Suitable as an upper-undergraduate textbook for mathematics students or as a fascinating, engaging, and fully illustrated resource for readers in physics and biology, Rebecca Hoyle's book, using a non-partisan approach, unifies a range of techniques used by active researchers in this growing field. Accessible description of the mathematical theory behind fascinating pattern formation in areas such as biology, physics and materials science Collects recent research for the first time in an upper level textbook Features a number of exercises - with solutions online - and worked examples

  15. Barrier Formation

    PubMed Central

    Lyaruu, D.M.; Medina, J.F.; Sarvide, S.; Bervoets, T.J.M.; Everts, V.; DenBesten, P.; Smith, C.E.; Bronckers, A.L.J.J.

    2014-01-01

    Enamel fluorosis is an irreversible structural enamel defect following exposure to supraoptimal levels of fluoride during amelogenesis. We hypothesized that fluorosis is associated with excess release of protons during formation of hypermineralized lines in the mineralizing enamel matrix. We tested this concept by analyzing fluorotic enamel defects in wild-type mice and mice deficient in anion exchanger-2a,b (Ae2a,b), a transmembrane protein in maturation ameloblasts that exchanges extracellular Cl− for bicarbonate. Defects were more pronounced in fluorotic Ae2a,b−/− mice than in fluorotic heterozygous or wild-type mice. Phenotypes included a hypermineralized surface, extensive subsurface hypomineralization, and multiple hypermineralized lines in deeper enamel. Mineral content decreased in all fluoride-exposed and Ae2a,b−/− mice and was strongly correlated with Cl−. Exposure of enamel surfaces underlying maturation-stage ameloblasts to pH indicator dyes suggested the presence of diffusion barriers in fluorotic enamel. These results support the concept that fluoride stimulates hypermineralization at the mineralization front. This causes increased release of protons, which ameloblasts respond to by secreting more bicarbonates at the expense of Cl− levels in enamel. The fluoride-induced hypermineralized lines may form barriers that impede diffusion of proteins and mineral ions into the subsurface layers, thereby delaying biomineralization and causing retention of enamel matrix proteins. PMID:24170372

  16. Rovibrationally selected ion-molecule collision study using the molecular beam vacuum ultraviolet laser pulsed field ionization-photoion method: Charge transfer reaction of N2+(X 2Σg+; v+ = 0-2; N+ = 0-9) + Ar

    NASA Astrophysics Data System (ADS)

    Chang, Yih Chung; Xu, Yuntao; Lu, Zhou; Xu, Hong; Ng, C. Y.

    2012-09-01

    We have developed an ion-molecule reaction apparatus for state-selected absolute total cross section measurements by implementing a high-resolution molecular beam vacuum ultraviolet (VUV) laser pulsed field ionization-photoion (PFI-PI) ion source to a double-quadrupole double-octopole ion-guide mass spectrometer. Using the total cross section measurement of the state-selected N2+(v+, N+) + Ar charge transfer (CT) reaction as an example, we describe in detail the design of the VUV laser PFI-PI ion source used, which has made possible the preparation of reactant N2+(X 2Σg+, v+ = 0-2, N+ = 0-9) PFI-PIs with high quantum state purity, high intensity, and high kinetic energy resolution. The PFI-PIs and prompt ions produced in the ion source are shown to have different kinetic energies, allowing the clean rejection of prompt ions from the PFI-PI beam by applying a retarding potential barrier upstream of the PFI-PI source. By optimizing the width and amplitude of the pulsed electric fields employed to the VUV-PFI-PI source, we show that the reactant N2+ PFI-PI beam can be formed with a laboratory kinetic energy resolution of ΔElab = ± 50 meV. As a result, the total cross section measurement can be conducted at center-of-mass kinetic energies (Ecm's) down to thermal energies. Absolute total rovibrationally selected cross sections σ(v+ = 0-2, N+ = 0-9) for the N2+(X 2Σg+; v+ = 0-2, N+ = 0-9) + Ar CT reaction have been measured in the Ecm range of 0.04-10.0 eV, revealing strong vibrational enhancements and Ecm-dependencies of σ(v+ = 0-2, N+ = 0-9). The thermochemical threshold at Ecm = 0.179 eV for the formation of Ar+ from N2+(X; v+ = 0, N+) + Ar was observed by the measured σ(v+ = 0), confirming the narrow ΔEcm spread achieved in the present study. The σ(v+ = 0-2; N+) values obtained here are compared with previous experimental and theoretical results. The theoretical predictions calculated based on the Landau-Zener-Stückelberg formulism are found to be in fair

  17. Interleukin-1β stimulates macrophage inflammatory protein-1α and -1β expression in human neuronal cells (NT2-N)

    PubMed Central

    Guo, Chang-Jiang; Douglas, Steven D.; Lai, Jian-Ping; Pleasure, David E.; Li, Yuan; Williams, Marge; Bannerman, Peter; Song, Li; Ho, Wen-Zhe

    2014-01-01

    Chemokines are important mediators in immune responses and inflammatory processes of neuroimmunologic and infectious diseases. Although chemokines are expressed predominantly by cells of the immune system, neurons also express chemokines and chemokine receptors. We report herein that human neuronal cells (NT2-N) produce macrophage inflammatory protein-1α and -1β (MIP-1α and MIP-1β), which could be enhanced by interleukin (IL)-1β at both mRNA and protein levels. The addition of supernatants from human peripheral blood monocyte-derived macrophage (MDM) cultures induced MIP-1β mRNA expression in NT2-N cells. Anti-IL-1β antibody removed most, but not all, of the MDM culture supernatant-induced MIP-1β mRNA expression in NT2-N cells, suggesting that IL-1β in the MDM culture supernatants is a major factor in the induction of MIP-1β expression. Investigation of the mechanism(s) responsible for IL-1β-induced MIP-1α and -1β expression demonstrated that IL-1β activated nuclear factor kappa B (NF-κB) promoter-directed luciferase activity in NT2-N cells. Caffeic acid phenethyl ester, a potent and specific inhibitor of activation of NF-κB, not only blocked IL-1β-induced activation of the NF-κB promoter but also decreased IL-1β-induced MIP-1α and -1β expression in NT2-N cells. These data suggest that NF-κB is at least partially involved in the IL-1β-mediated action on MIP-1α and -1β in NT2-N cells. IL-1β-mediated up-regulation of β-chemokine expression may have important implications in the immuno-pathogenesis of inflammatory diseases in the CNS. PMID:12603824

  18. Towards orbital dating of the EPICA Dome C ice core using δO2/N2

    NASA Astrophysics Data System (ADS)

    Landais, A.; Dreyfus, G.; Capron, E.; Pol, K.; Loutre, M. F.; Raynaud, D.; Lipenkov, V. Y.; Arnaud, L.; Masson-Delmotte, V.; Paillard, D.; Jouzel, J.; Leuenberger, M.

    2012-01-01

    Based on a composite of several measurement series performed on ice samples stored at -25 °C or -50 °C, we present and discuss the first δO2/N2 record of trapped air from the EPICA Dome C (EDC) ice core covering the period between 300 and 800 ka (thousands of years before present). The samples stored at -25 °C show clear gas loss affecting the precision and mean level of the δO2/N2 record. Two different gas loss corrections are proposed to account for this effect, without altering the spectral properties of the original datasets. Although processes at play remain to be fully understood, previous studies have proposed a link between surface insolation, ice grain properties at close-off, and δO2/N2 in air bubbles, from which orbitally tuned chronologies of the Vostok and Dome Fuji ice core records have been derived over the last four climatic cycles. Here, we show that limitations caused by data quality and resolution, data filtering, and uncertainties in the orbital tuning target limit the precision of this tuning method for EDC. Moreover, our extended record includes two periods of low eccentricity. During these intervals (around 400 ka and 750 ka), the matching between δO2/N2 and the different insolation curves is ambiguous because some local insolation maxima cannot be identified in the δO2/N2 record (and vice versa). Recognizing these limitations, we restrict the use of our δO2/N2 record to show that the EDC3 age scale is generally correct within its published uncertainty (6 kyr) over the 300-800 ka period.

  19. Update of ENDL U(n,2n), U(n,gamma), U(n,f) Evaluations

    SciTech Connect

    Beck, B; Brown, D A; McNabb, D P

    2004-02-13

    The authors are in the re-evaluating of all the actinide cross section evaluations in LLNL's ENDL database, starting with uranium and focusing on inventory changing reactions. This article describes their first serious pass at updating the uranium cross section data, including estimates of cross section uncertainties. Furthermore, they are developing new tools to automate the re-evaluation and this article contains some preliminary results from these codes, namely the {sup 235}U(n, 2n) and {sup 238}U(n, 2n) evaluations.

  20. B2N2O4: Prediction of a Magnetic Ground State for a Light Main-Group Molecule

    SciTech Connect

    Varga, Zoltan; Truhlar, Donald G.

    2015-09-08

    Cyclobutanetetrone, (CO)4, has a triplet ground state. Here we predict, based on electronic structure calculations, that the B2N2O4 molecule also has a triplet ground state and is therefore paramagnetic; the structure is an analogue of (CO)4 in which the carbon ring is replaced by a (BN)2 ring. Similar to (CO)4, the triplet ground-state structure of B2N2O4 is also thermodynamically unstable. Besides analysis of the molecular orbitals, we found that the partial atomic charges are good indicators for predicting magnetic ground states.

  1. Novel substituted (Z)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-one and (Z)-(+/-)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-ol derivatives as potent thermal sensitizing agents.

    PubMed

    Sonar, Vijayakumar N; Thirupathi Reddy, Y; Sekhar, Konjeti R; Sasi, Soumya; Freeman, Michael L; Crooks, Peter A

    2007-12-15

    Use of ionizing radiation is essential for the management of many human cancers, and therapeutic hyperthermia has been identified as a potent radiosensitizer. Radiation therapy combined with adjuvant hyperthermia represents a potential tool to provide outstanding local-regional control for refractory disease. (Z)-(+/-)-2-(N-Benzylindol-3-ylmethylene)quinuclidin-3-ol (2) and (Z)-(+/-)-2-(N-benzenesulfonylindol-3-ylmethylene)quinuclidin-3-ol (4) were initially identified as potent thermal sensitizers that could lower the threshold needed for thermal sensitivity to radiation treatment. To define the structural requirements of the molecule that are essential for thermal sensitization, we have synthesized and evaluated a series of (Z)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-one (9), and (Z)-(+/-)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-ol (10) analogs that incorporate a variety of substituents in both the indole and N-benzyl moieties. These systematic structure-activity relationship (SAR) studies were designed to further the development and optimization of potential clinically useful thermal sensitizing agents. The most potent analog was compound 10 (R(1)=H, R(2)=4-Cl), which potently inhibited (93% inhibition at 50 microM) the growth of HT-29 cells after a 41 degrees C/2h exposure.

  2. Accurate age scale of the Dome Fuji ice core, Antarctica from O2/N2 ratio of trapped air

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Aoki, S.; Nakazawa, T.; Suzuki, K.; Parrenin, F.

    2012-04-01

    Chronology of the first Dome Fuji deep ice core (core length: 2,500 m, ice thickness: 3,035 m) for the age range from 80 kyr to 340 kyr ago was established by orbital tuning of measured O2/N2 ratios in trapped air to local summer insolation, with precision better than about 2,000 years (Kawamura et al., 2007). The O2/N2 ratios found in polar ice cores are slightly lower than the atmospheric ratio because of size-dependent molecular fractionation during bubble close-off. The magnitude of this gas fractionation is believed to be governed by the magnitude of snow metamorphism when the layer was originally at the surface, which in turn is controlled by local summer insolation (Fujita et al., 2009). A strong advantage of the O2/N2 chronology is that there is no need to assume a lag between climatic records in the ice core and orbital forcings, becacuse O2/N2 ratios record local insolation through physical processes. Accuracy of the chronology was validated by comparing the O2/N2 chronology with U-Th radiometric chronology of speleothem records (Cheng et al., 2009) for the ends of Terminations II, III and IV, as well as several large climatic events, for which both ice-core CH4 and speleothem δ18O (a proxy for precipitation) show abrupt shifts as seen in the last glacial period. All ages from O2/N2 and U-Th chronology agreed with each other within ~2,000 yr. The O2/N2 chronology permits comparisons between Antarctic climate, greenhouse gases, astronomically calculated orbital parameters, and radiometrically-dated sea level and monsoon records. Here, we completed the measurements of O2/N2 ratios of the second Dome Fuji ice core, which reached bedrock, for the range from 2,400 to 3,028 m (320 - 700 kyr ago) at approximately 2,000-year time resolution. We made significant improvements in ice core storage practices and mass spectrometry. In particular, the ice core samples were stored at about -50 ° C until the air extraction, except during short periods of transportation

  3. Analysis of gene expression during flowering in apomeiotic mutants of Medicago spp.: cloning of ESTs and candidate genes for 2n eggs.

    PubMed

    Barcaccia, G; Varotto, S; Meneghetti, S; Albertini, E; Porceddu, A; Parrini, P; Lucchin, M

    2001-12-01

    Mutants showing features of apomixis have been documented in alfalfa (Medicago sativa L.), a natural outcrossing sexual species. A differential display of mRNAs that combines cDNA-AFLP markers and bulked segregant analysis was carried out with the aim of selecting expressed sequence tags (ESTs) and cloning candidate genes for apomeiosis in mutants of alfalfa characterized by 2n egg formation at high frequencies. The approach enabled us to select either mutant- or wild type-specific transcript derived-fragments and to detect transcriptional changes potentially related to 2n eggs. Sequence alignments of a subset of 40 polymorphic clones showed significant homologies to genes of known function. An EST with identity to a β-tubulin gene, highly expressed in the wild type and poorly expressed in the apomeiotic mutants, and an EST with identity to a Mob1-like gene, qualitatively polymorphic between pre- and post-meiotic stages, were selected as candidate genes for apomeiosis because of their putative roles in the cell cycle. A number of clone-specific primers were designed for performing both 5' and 3' rapid amplification of cDNA ends to obtain the full-length clones. Southern blot hybridization revealed that both clones belong to a multi-gene family with a minimum of three genomic DNA members each. Northern blot hybridization of total RNA samples and in situ hybridization of whole buds enabled the definition of their temporal and spatial expression patterns in reproductive organs. Experimental achievements towards the elucidation of apomeiotic megasporogenesis in alfalfa are presented and discussed.

  4. Broadband Screening for Interstellar Species: Additional Laboratory Measurements and Interstellar Detection of Ethanimine (CH3CHNH) in Sgr B2(N) Using GBT PRIMOS Survey Data

    NASA Astrophysics Data System (ADS)

    Loomis, Ryan; Zaleski, D.; Steber, A.; Neill, J.; Muckle, M. T.; Harris, B. J.; Seifert, N.; Pate, B.; Lattanzi, V.; Martinez, O.; McCarthy, M. C.; Remijan, A. J.

    2013-01-01

    As the availability of publicly accessible spectral line surveys from radio astronomy increases, new approaches to the identification of molecules in the interstellar medium are possible. We have performed reaction product screening measurements using broadband rotational spectroscopy to identify potential matches in the laboratory and radio astronomy spectra. A broadband spectrum of an electrical discharge of CH3CN and H2S contained several matches to unidentified features in the GBT PRIMOS Survey1 of Sgr B2(N) that did not have molecular assignments in the radio astronomy spectral catalogs. These transitions have been assigned to the E- and Z-isomers of ethanimine (CH3CHNH). The rotational spectrum of the E- and Z-isomers of CH3CHNH have been reported at mm-wave frequencies in 1980 by Lovas et al.2 and then in 1981 by Brown et al.3 The analysis of the rotational spectra of these two isomers has been extended to the microwave frequency region to verify the assignments from the GBT PRIMOS Survey. Combined fits over the range of 8 to 130GHz consisting of data from Lovas et al., broadband CP-FTMW measurements, and cavity double resonance measurements are presented for both isomers. Evidence for the detection of both isomers in Sgr B2(N) is shown along with a discussion of the method of their detection and a brief analysis of possible formation routes. 1. GBT PRIMOS Survey, http://www.cv.nrao.edu aremijan/PRIMOS 2. F.J. Lovas, R.D. Suenram, D.R. Johnson, F.O. Clark, E. Tiemann, J. Chem. Phys., 72, 4964-4972, (1980). 3. R.D. Brown, P.D. Godfrey, D.A. Winkler, Chem. Phys., 59, 243-247, (1981).

  5. Theoretical investigations of structural, electronic and elastic properties of U2S3 type Nb2N3 under high pressure

    NASA Astrophysics Data System (ADS)

    Zhang, Ji-Dong; Huang, Xiao-Yu

    2015-01-01

    The structural, electronic and elastic properties of U2S3 type Nb2N3 under pressure ranging from 0 GPa to 100 GPa are investigated by plane-wave pseudopotential density functional theory with the generalized gradient approximation in this paper. The results at zero pressure are in good agreement with available theoretical results. The properties of U2S3 type Nb2N3 are compared to the new synthetic superhard material η-Ta2N3. The results show that U2S3 type Nb2N3 is hard to compress, and expected to have comparable hardness to η-Ta2N3.

  6. Laboratory experiments for Titan's ionosphere : the chemistry of N2+, N+, and N2++ nitrogen ions

    NASA Astrophysics Data System (ADS)

    Thissen, R.; Alcaraz, C.; Dutuit, O.; Nicolas, C.; Soldi-Lose, H.; Zabka, J.; Franceschi, P.

    Laboratory experiments for Titan's ionosphere : the chemistry of N+ , N+ , and N2+ nitrogen ions 2 2 R. Thissen (1), C. Alcaraz (1), O. Dutuit (1), C. Nicolas (2), H. Soldi-Lose (3), J. Zabka (4), P. Franceschi (5) (1) LCP, Bât. 350, Centre Universitaire Paris-Sud, F-91405 Orsay Cedex, France, (2) Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin BP 48, 91192 Gif-sur-Yvette, France, (3) Institut für Chemie, Fachgruppe Organische Chemie, Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, (4) J. Heyrovsky Institute of Physical Chemistry, Dolejskova 3, CZ 18223 Praha 8 - Kobylisy, Czech Republik, (5) Dept. of Physics, University of Trento, Via Sommarive 14, 38050 Povo (TN), Italy (christian.alcaraz@lcp.u-psud.fr) N2 is the major neutral componant of Titan's atmosphere, its ionisation by solar radiation and by magnetospheric electron impact is the most important production of ions in Titan's ionosphere. These primary processes not only lead to N+ molecular 2 monocations but also to N+ atomic ions and to N2+ molecular dications, which can 2 pertain some internal or translational excitation. This contribution will summarize our efforts to caracterize in gaz phase laboratory experiments the reactivity of the nitrogen ions with the most important neutral targets of the Titan's atmosphere [1-3]: • N+ + CH4 , C2 H2 , and C2 H6 2 • N+ (3 P, 1 D) + CH4 , and C2 H4 • N2+ + N2 , CH4 , and C2 H4 2 In this work, particular attention has been paid on the effect of internal and/or translational excitation of the primary nitrogen ions on the rate constant and branching ratio of these ion-molecule reactions. The results from these studies have been compared to the literature values when available and some significant differences have been found. These new values have been used as input data in 1D models of the Titan's ionosphere to show the effect on the final density profiles of the main ions [4] and to demonstrate the existence of a N2+2 dication

  7. Spectroscopic, and electrochemical studies of [MCl2(η2-N,N-dpksc)] (M = Zn, Cd, Hg and dpksc = di-2-pyridylketone semicarbazone)

    NASA Astrophysics Data System (ADS)

    Bakir, Mohammed; McDermot, Covel; Johnson, Toni

    2013-05-01

    A series of group 12 metal chlorides of dpksc of the type [MCl2(η2-N,N-dpksc)] (M = Zn, Cd and Hg) were synthesized from the reactions between MCl2 and dpksc in refluxing CH3CN. Spectroscopic measurements performed on protophilic solutions of [MCl2(η2-N,N-dpksc)] divulged sensitivity of [MCl2(η2-N,N-dpksc)] to changes in their surroundings. Variable temperature 1H NMR studies revealed the amine protons to be more sensitive to temperature variations compared to the amide and aromatic protons. Electronic absorption spectral measurements disclosed acid-base inter-conversion between [MCl2(η2-N,N-dpksc)] and its conjugate base [MCl2(η2-N,N-dpksc-H)]-. In dmf, the acidity of [MCl2(η2-N,N-dpksc)] increases in the following order: [ZnCl2(η2-N,N-dpksc)] > [CdCl2(η2-N,N-dpksc)] > [HgCl2(η2-N,N-dpksc)]. The electrochemical properties of [MCl2(η2-N,N-dpksc)] are dominated by a series of irreversible redox transformations pointing to electrochemical decomposition of [MCl2(η2-N,N-dpksc)] upon electronic transfers.

  8. COMPLETE SUPPRESSION OF THE M=2/N-1 NEOCLASSICAL TEARING MODE USING ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D

    SciTech Connect

    PETTY,CC; LAHAYE,LA; LUCE,TC; HUMPHREYS,DA; HYATT,AW; PRATER,R; STRAIT,EJ; WADE,MR

    2003-03-01

    A271 COMPLETE SUPPRESSION OF THE M=2/N-1 NEOCLASSICAL TEARING MODE USING ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D. The first suppression of the important and deleterious m=2/n=1 neoclassical tearing mode (NTM) is reported using electron cyclotron current drive (ECCD) to replace the ''missing'' bootstrap current in the island O-point. Experiments on the DIII-D tokamak verify the maximum shrinkage of the m=2/n=1 island occurs when the ECCD location coincides with the q = 2 surface. The DIII-D plasma control system is put into search and suppress mode to make small changes in the toroidal field to find and lock onto the optimum position, based on real time measurements of dB{sub {theta}}/dt, for complete m=2/n=1 NTM suppression by ECCD. The requirements on the ECCD for complete island suppression are well modeled by the modified Rutherford equation for the DIII-D plasma conditions.

  9. On the long-term stability of reference gases for atmospheric O2/N2 and CO2 measurements

    NASA Astrophysics Data System (ADS)

    Keeling, Ralph F.; Manning, Andrew C.; Paplawsky, William J.; Cox, Adam C.

    2007-02-01

    Measurements of changes in the atmospheric O2/N2 ratio have typically relied on compressed air derived from high-pressure tanks as the reference material against which atmospheric changes are assessed. The validity of this procedure is examined here in the context of the history of 18 O2/N2 reference tanks compared over a 12-yr time-frame. By considering differences in tank sizes, material types, and by performing additional tests, the long-term stability of the delivered gas is evaluated with respect to surface reactions, leakage, regulator effects, and thermal diffusion and gravimetric fractionation. Results are also reported for the stability of CO2 in these tanks. The results emphasize the importance of orienting tanks horizontally within a thermally insulated enclosure to reduce thermal and gravimetric fractionation of both O2/N2 and CO2 concentrations, and they emphasize the importance of avoiding elastomeric O-rings at the head-valve base. With the procedures documented here, the long-term drift in O2/N2 appears to be zero to within approximately +/-0.4 per meg yr-1, which projects to an uncertainty of +/-0.16 Pg C yr-1 (1σ) in O2-based global carbon budgets.

  10. Unusual solvatochromic absorbance probe behaviour within mixtures of poly(ethylene glycol)-400 + ionic liquid, [bmim][Tf2N

    NASA Astrophysics Data System (ADS)

    Ali, Anwar; Ali, Maroof; Malik, Nisar Ahmad; Uzair, Sahar

    2014-03-01

    The potentially green solvents made up of ionic liquids (ILs) and poly(ethylene glycols) may have wide range of the applications in many chemical and biochemical fields. In the present work, solvatochromic absorbance probe behaviour is used to assess the physicochemical properties of the mixtures composed of PEG-400 + IL, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [bmim][Tf2N]. Lowest energy intramolecular charge-transfer absorbance maxima of a betaine dye, i.e., ETN , indicates the dipolarity/polarizability and/or hydrogen-bond donating (HBD) acidity of the [bmim][Tf2N] + PEG-400 mixtures to be even higher than that of neat [bmim][Tf2N], the solution component with higher dipolarity/polarizability and/or HBD acidity. Dipolarity/polarizability (π∗) obtained separately from the electronic absorbance response of probe N,N-diethyl-4-nitroaniline, and the HBD acidity (α) of PEG-400 + [bmim][Tf2N] mixtures are also observed to be anomalously high. A comparative study of the PEG + IL mixtures has also been done with PEG-400 + molecular organic solvents (protic polar [methanol], aprotic polar [N,N-dimethylformamide], and non polar, [benzene]) mixtures, but these mixtures do not show this type of unusual behaviour. A four-parameter simplified combined nearly ideal binary solvent/Redlich-Kister (CNIBS/R-K) equation is shown to satisfactorily predict the solvatochromic parameters within PEG-400 + different solvent mixtures.

  11. Towards orbital dating of the EPICA Dome C ice core using δO2/N2

    NASA Astrophysics Data System (ADS)

    Landais, A.; Dreyfus, G.; Capron, E.; Pol, K.; Loutre, M. F.; Raynaud, D.; Lipenkov, V. Y.; Arnaud, L.; Masson-Delmotte, V.; Paillard, D.; Jouzel, J.; Leuenberger, M.

    2011-06-01

    Based on a composite of several measurement series performed on ice samples stored at -25 °C or -50 °C, we present and discuss the first δO2/N2 record of trapped air from the EPICA Dome C (EDC) ice core covering the period between 300 and 800 ka (thousands of years before present). The samples stored at -25 °C show clear gas loss affecting the precision and mean level of the δO2/N2 record. Two different gas loss corrections are proposed to account for this effect, without altering the spectral properties of the original datasets. Although processes at play remain to be fully understood, previous studies have proposed a link between surface insolation, ice grain properties at close-off and δO2/N2 in air bubbles, from which an orbitally tuned chronologies of the Vostok and Dome Fuji ice core records have been derived over the last four climatic cycles. Here, we show that limitations caused by data quality and resolution, data filtering and uncertainties in the orbital tuning target limit the precision of this tuning method for EDC to at least 2.5 kyrs (thousands of years). Moreover, our extended record includes two periods of low eccentricity. During these intervals (around 400 ka and 750 ka), the matching between δO2/N2 and the different insolation curves is ambiguous because some local insolation maxima cannot be identified in the δO2/N2 record (and vice versa). Recognizing these limitations, we restrict the use of our δO2/N2 record to show that the EDC3 age scale is generally correct within its published uncertainty (6 kyrs) over the 300-800 ka period. We illustrate the uncertainties associated with data quality, filtering and tuning target for periods of low eccentricity by highlighting the difficulty to constrain the duration of Marine Isotopic Stage 11 based on the EDC δO2/N2 information.

  12. The relationship between the effects of UV light and thermal shock on gametes and the viability of early developmental stages in a marine teleost fish, the sea bass (Dicentrarchus labrax L.).

    PubMed

    Felip, A; Piferrer, F; Carrillo, M; Zanuy, S

    1999-10-01

    To improve the efficiency of gynogenetic induction, the effects of UV light and thermal shock on gametes were investigated in the sea bass. Exposure of sperm to UV light (>/=15 000 erg mm-2) reduced the amount of motile spermatozoa, without affecting the duration of motility in the spermatozoa that remained motile. The Hertwig effect was elicited in eggs fertilized with sperm exposed to >/=35 000 erg mm-2 of UV light, indicating the inactivation of the DNA of the spermatozoa while retaining their ability to trigger development. Resulting embryos (24 chromosomes; one NOR) exhibited the haploid syndrome and died at hatch. Diploidy was restored in eggs fertilized with irradiated sperm by blocking meiosis II with a thermal shock (0 +/- 0.5 degrees C for 10 min, starting 5 min after fertilization). Resulting larvae ( approximately 35% survival at hatching) had 48 chromosomes, one or two NOR and no paternal chromosome fragments (gynogenetic diploids). In eggs fertilized with sperm not exposed to UV light, the same thermal shock induced 100% triploidy (72 chromosomes; one, two or three NOR), with 70% survival at hatching. Multifactorial ANOVA showed that, compared to external factors (sperm diluent, UV light and thermal shock), the contribution of broodstock to the viability of the early developmental stages was not significant (P > 0.05). Effects of the thermal shock were most evident after fertilization (30.7%) but disappeared (0%) at hatching, suggesting that the lower survival of triploids is a consequence of handling, not of the triploid condition per se. However, effects of UV light increased through development (42.5-69.7%), probably reflecting cumulative deficits in protein synthesis. PMID:10583540

  13. Phosphorylation and cellular function of the human Rpa2 N-terminus in the budding yeast Saccharomyces cerevisiae.

    PubMed

    Ghospurkar, Padmaja L; Wilson, Timothy M; Liu, Shengqin; Herauf, Anna; Steffes, Jenna; Mueller, Erica N; Oakley, Gregory G; Haring, Stuart J

    2015-02-01

    Maintenance of genome integrity is critical for proper cell growth. This occurs through accurate DNA replication and repair of DNA lesions. A key factor involved in both DNA replication and the DNA damage response is the heterotrimeric single-stranded DNA (ssDNA) binding complex Replication Protein A (RPA). Although the RPA complex appears to be structurally conserved throughout eukaryotes, the primary amino acid sequence of each subunit can vary considerably. Examination of sequence differences along with the functional interchangeability of orthologous RPA subunits or regions could provide insight into important regions and their functions. This might also allow for study in simpler systems. We determined that substitution of yeast Replication Factor A (RFA) with human RPA does not support yeast cell viability. Exchange of a single yeast RFA subunit with the corresponding human RPA subunit does not function due to lack of inter-species subunit interactions. Substitution of yeast Rfa2 with domains/regions of human Rpa2 important for Rpa2 function (i.e., the N-terminus and the loop 3-4 region) supports viability in yeast cells, and hybrid proteins containing human Rpa2 N-terminal phospho-mutations result in similar DNA damage phenotypes to analogous yeast Rfa2 N-terminal phospho-mutants. Finally, the human Rpa2 N-terminus (NT) fused to yeast Rfa2 is phosphorylated in a manner similar to human Rpa2 in human cells, indicating that conserved kinases recognize the human domain in yeast. The implication is that budding yeast represents a potential model system for studying not only human Rpa2 N-terminal phosphorylation, but also phosphorylation of Rpa2 N-termini from other eukaryotic organisms.

  14. Optical and electrical properties of Ti(Cr)O2:N thin films deposited by magnetron co-sputtering

    NASA Astrophysics Data System (ADS)

    Kollbek, K.; Szkudlarek, A.; Marzec, M. M.; Lyson-Sypien, B.; Cecot, M.; Bernasik, A.; Radecka, M.; Zakrzewska, K.

    2016-09-01

    The paper deals with TiO2-based thin films, doped with Cr and N, obtained by magnetron co-sputtering from titanium dioxide ceramic and chromium targets in Ar + N2 atmosphere. Co-doped samples of Ti(Cr)O2:N are investigated from the point of view of morphological, crystallographic, optical, and electrical properties. Characterization techniques such as: X-ray diffraction, XRD, scanning electron microscopy, SEM, atomic force microscopy, AFM, Energy Dispersive X-ray spectroscopy, EDX, X-ray photoelectron spectroscopy, XPS, optical spectrophotometry as well as impedance spectroscopy are applied. XRD reveals TiO2 and TiO2:N thin films are well crystallized as opposed to those of TiO2:Cr and Ti(Cr)O2:N. XPS spectra confirm that co-doping has been successfully performed with the biggest contribution from the lower binding energy component of N 1s peak at 396 eV. SEM analysis indicates uniform and dense morphology without columnar growth. Comparison between the band gaps indicates a significant shift of the absorption edge towards visible range from 3.69 eV in the case of non-stoichiometric Ti(Cr)O2-x:N to 2.78 eV in the case of stoichiometric Ti(Cr)O2:N which should be attributed to the incorporation of both dopants at substitutional positions in TiO2 lattice. Electrical conductivity of stoichiometric Ti(Cr)O2:N increases in comparison to co-doped nonstoichiometric TiO2-x thin film and reaches almost the same value as that of TiO2 stoichiometric film.

  15. Apospory appears to accelerate onset of meiosis and sexual embryo sac formation in sorghum ovules

    PubMed Central

    2011-01-01

    Background Genetically unreduced (2n) embryo sacs (ES) form in ovules of gametophytic apomicts, the 2n eggs of which develop into embryos parthenogenetically. In many apomicts, 2n ES form precociously during ovule development. Whether meiosis and sexual ES formation also occur precociously in facultative apomicts (capable of apomictic and sexual reproduction) has not been studied. We determined onset timing of meiosis and sexual ES formation for 569 Sorghum bicolor genotypes, many of which produced 2n ES facultatively. Results Genotype differences for onset timing of meiosis and sexual ES formation, relative to ovule development, were highly significant. A major source of variation in timing of sexual germline development was presence or absence of apomictic ES, which formed from nucellar cells (apospory) in some genotypes. Genotypes that produced these aposporous ES underwent meiosis and sexual ES formation precociously. Aposporous ES formation was most prevalent in subsp. verticilliflorum and in breeding lines of subsp. bicolor. It was uncommon in land races. Conclusions The present study adds meiosis and sexual ES formation to floral induction, apomictic ES formation, and parthenogenesis as processes observed to occur precociously in apomictic plants. The temporally diverse nature of these events suggests that an epigenetic memory of the plants' apomixis status exists throughout its life cycle, which triggers, during multiple life cycle phases, temporally distinct processes that accelerate reproduction. PMID:21223576

  16. Energetic Improvements by N-Oxidation: Insensitive Amino-Hydroximoyl-Tetrazole-2N-Oxides

    NASA Astrophysics Data System (ADS)

    Klapötke, Thomas M.; Kurz, Matthias Q.; Schmid, Philipp C.; Stierstorfer, Jörg

    2015-07-01

    5-Aminohydroximoyl-2-hydroxytetrazole (3) was synthesized in a three-step synthesis from inexpensive starting materials. This novel tetrazole derivative contains two energetic moieties: an N-oxide as well as an aminohydroximoyl group. Various energetic nitrogen-rich salts such as hydroxylammonium (4), guanidinium (5), aminoguanidinium (6), ammonium (7), and triaminoguanidinium (8) were synthesized. Moreover, zwitterionic 5-amidrazonyl-tetrazole-2-oxide monohydrate (9) was synthesized. Compounds 4, 5, 8, 9, and 10 were structurally characterized using single-crystal X-ray diffraction. Additionally, all new compounds were characterized using nuclear magnetic resonance (NMR) and vibrational (infrared [IR], Raman) spectroscopy as well as mass spectrometry and elemental analysis. The thermal behavior was studied using differential thermal analysis (DTA) measurements and the sensitivities of the compounds toward shock, friction, and electrostatic discharge were determined. Finally, the enthalpies of formation were calculated (atomization method, CBS-4 M enthalpies) and several detonation/propulsion parameters computed with the EXPLO5 code.

  17. Crystal structure of fac-aquatricarbonyl[(S)-valin-ato-κ(2) N,O]-rhenium(I).

    PubMed

    Piletska, Kseniia O; Domasevitch, Kostiantyn V; Shtemenko, Alexander V

    2016-04-01

    In the mol-ecule of the title compound, [Re(C5H10NO2)(CO)3(H2O)], the Re(I) atom adopts a distorted octa-hedral coordination sphere defined by one aqua and three carbonyl ligands as well as one amino N and one carboxyl-ate O atom of the chelating valinate anion. The carbonyl ligands are arranged in a fac-configuration around the Re(I) ion. In the crystal, an intricate hydrogen-bonding system under participation of two O-H, two N-H and one C-H donor groups and the carboxyl-ate and carbonyl O atoms as acceptor groups contribute to the formation of a three-dimensional supra-molecular network. PMID:27375894

  18. Spectroscopic evidence on improvement in complex formation of O2N2 aza-crown macrocyclic ligands with Cu(II) acetate upon incorporation with [60]Fullerene.

    PubMed

    Ghanbari, Bahram; Gholamnezhad, Parisa

    2016-12-01

    The present paper reports the spectroscopic investigations on the complexation of Cu(II) with two macrocyclic ligands bonded to [60]Fullerene (L1 and L2) measured in N-methylpyrrolidone (NMP) as solvent. On the basis of UV-vis-NIR spectroscopy applying Jobs method of continuous variation, typical 1:1 stoichiometries were established for the complexes of Cu(II) with L1, and L2. DFT calculations suggested that superior HOMO distributions spread over the nitrogen-donor (as well as somehow oxygen- donor in L2) groups of L1 and L2 macrocycles were the key factor for the observed Kb value enhancement. Thermodynamic stabilities for these complexes have also been determined employing Benesi-Hildebrand equation and the results were compared in terms of their calculated binding constants (Kb). These measurements showed that L1 and L2 bound to these cations stronger than their parent free macrocyclic ligands 1 and 2, respectively. Furthermore, Kb values found for L2 complexes revealed that it could coordinate Cu(II) cation better than L1. Thermodynamic parameters (ΔG, ∆H, and -ΔS) derived from Van't Hoff equation showed that L1 and L2 coordination of Cu(II) cation were occurred due to both enthalpic and entropic factors while the coordination of Cu(II) with their parent macrocyclic ligands 1 and 2 only enjoyed from only enthalpic advantages. PMID:27380303

  19. Regional differences in the δO2/N2 records from East Antarctica over the last interglacial

    NASA Astrophysics Data System (ADS)

    Bazin, L.; Landais, A.; Masson-Delmotte, V.; Kageyama, M.; Paillard, D.; Bopp, L.; Ritz, C.; Leuenberger, M.

    2013-12-01

    Ice cores are the only climate archives offering samples of past atmosphere. The air is trapped at around 100 m under the surface, where the snow is compacted into ice. During this process, multiple influences may modify the air composition as the quantity of insolation received at the surface impacts snow metamorphism and hence air trapping conditions at the basis of the firn (top ~100m of the ice sheet). Analyses of trapped air in ice cores thus give us information on both local and global scales. In this study, we focus on temporal variations of elemental and isotopic composition of oxygen from East Antarctic ice cores. On the one hand, the δ18Oatm, uniformly distributed in the atmosphere, is known to be related to the hydrological cycle and the vegetation cover (Landais et al., 2010), and can be linked to the precession variations. The δO2/N2, on the other hand, appears to be influenced by the local insolation, probably because of modification of the snow structure affecting pore close-off. These two quantities have largely been used as orbital tuning tools for dating purposes in several ice cores from Antarctica (Bender 2002, Suwa et Bender 2008, Kawamura et al., 2007, Dreyfus et al., 2007,Landais et al., 2012, Bazin et al., 2013). Still, gaps in our understanding of the exact mechanisms explaining the δ18Oatm and δO2/N2 variations lead to quite large uncertainties when using these proxies as tie-points for dating purposes. In this study, we use several ice core records in low accumulation rate sites of East Antarctica to decipher global and local effects on the δO2/N2 records. First, we present a compilation of δO2/N2 measurements of the Dome F, Vostok and Dome C ice cores over the last interglacial period. While Dome F and Vostok data were corrected for gas loss during several years of storage at -25°C, new measurements of the air isotopic composition on the Dome C ice core were performed on well-conserved ice (-50°C). Different δO2/N2 mean levels

  20. Dielectric barrier discharge plasma treatment on E. coli: Influence of CH{sub 4}/N{sub 2}, O{sub 2}, N{sub 2}/O{sub 2}, N{sub 2}, and Ar gases

    SciTech Connect

    Majumdar, Abhijit; Hippler, Rainer; Singh, Rajesh Kumar; Palm, Gottfried J.

    2009-10-15

    Atmospheric pressure dielectric barrier discharge (DBD) plasma has been employed on Gram-negative bacteria, Escherichia coli BL21. Treatment was carried out using plasma generated with different compositions of gases: CH{sub 4}/N{sub 2} (1:2), O{sub 2}, N{sub 2}/O{sub 2} (1:1), N{sub 2}, and Ar, and by varying plasma power and treatment time. E. coli cells were exposed under the DBD plasma in triplicates, and their surviving numbers were observed in terms of colony forming units. It has been observed that the CH{sub 4}/N{sub 2} plasma exhibits relatively higher sterilization property toward E. coli compared to plasma generated by using O{sub 2}, N{sub 2}/O{sub 2}, N{sub 2}, and Ar gas mixtures. The time to kill up to 90% of the initial population of the E. coli cells was found to be about 2-3 min for CH{sub 4}/N{sub 2} and O{sub 2} gas mixture DBD plasma. A prolongation of treatment time and an increase in the dissipated power significantly improved the E. coli killing efficiency of the atmospheric pressure DBD plasma.