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Sample records for 2n gamete formation

  1. Nature of 2n gamete formation and mode of inheritance in interspecific hybrids of diploid Vaccinium darrowi and tetraploid V. corymbosum.

    PubMed

    Qu, L; Hancock, J F

    1995-12-01

    RAPD markers were used to determine the level of heterozygosity transmitted via 2n gametes from V. darrowi selection Florida 4B (Fla 4B) to inter-specific hybrids with tetraploid V. corymbosum cv Bluecrop. The tetraploid hybrid US 75 was found to contain about 70% of Fla 4B's heterozygosity, a value attributed to a first-division restitution (FDR) mode of 2n gamete production. Crossovers during 2n gamete formation were evidenced by the absence of 16 dominant alleles of Fla 4B in US 75, and direct tests of segregation in a diploid population involving Fla 4B. RAPD markers that were present in both Fla 4B and US 75 were used to determine the mode of inheritance in a segregating population of US 75xV. corymbosum cv Bluetta. Thirty-one duplex loci were identified which segregated in a 5∶1 ratio, indicating that US 75 undergoes tetrasomic inheritance.

  2. [Studies of the meiosis of 2n gamete apomictic wheat grass (Elymus rectisetus)].

    PubMed

    Li, M T; Cai, D T; Huang, L M

    2001-01-01

    The formation of polyploid was mainly through the combination of 2n gamete, and the apomixis played an important role in plant evolution and plant breeding. In general, the formation of male gamete and female gamete in apomictic plants are obviously different, i.e., the formation of embryo sac was through apomixis (form into 2n female gamete); however, the formation of male gamete was through normal meiosis (form into 1n male gamete). The 2n male gamete apomictic wheat grass was more important than 1n male gamete apomictic wheat grass, because the 2n male gamete can bring all genes including apomictic gene into other plant. The meiosis of 2n male gamete apomictic wheat grass (Elymus. rectisetus) was observed through Olympus AH3 microscope; the results showed that the meiosis of 2n gamete apomictic wheat grass was very abnomal. In the interphase, lots of mini-nucleus were found. Inverted cycle, multibivalent and lagging chromosome were also found in the prophase. In metaphase, chromosomes frequently show unequal division tendency; In anaphase I and telophase I, completely unequal division, modified meiosis, the tendency of nucleus fusion and other abnormal phenomena were found. These phenomena directly lead to the production of 2n gamete. In meiosis II, the abnormalities mainly lie in the proceeding of microspore, dyad (55.7%), triad (23.7%) and tetrad (21.6%) were found. The abnormal of those proceeding also lead to the production of 2n gamete.

  3. The role of 2n gametes and endosperm balance number in the origin and evolution of polyploids in the tuber-bearing Solanums.

    PubMed Central

    Carputo, Domenico; Frusciante, Luigi; Peloquin, Stanley J

    2003-01-01

    Polyploidization has played a major role in the origin and evolution of polyploid species. In this article we outline the unique characteristics of 2n gametes and implications of their participation in the evolution of polyploid Solanum species. The genetic consequences of 2n gametes indicate that sexual polyploidization results in greater variability, fitness, and heterozygosity than does somatic doubling. Further, the mechanisms of 2n gamete formation and the frequency of 2n gamete-forming genes in present polyploids and their ancestral species provide additional evidence of their involvement. Equally important is the endosperm, via the endosperm balance number (EBN) incompatibility system, in complementing the role of 2n gametes. In fact, the EBN system acts as a screen for either 1n or 2n gametes, depending on the EBN and chromosome numbers of parental species. EBN in combination with 2n gametes maintains the ploidy integrity of diploid ancestral species, while providing the flexibility for either unilateral or bilateral sexual polyploidization. PMID:12586716

  4. Evidence for the existence of 2n gametes in Lotus tenuis Wald. et Kit. (2n=2x=12): their relevance in evolution and breeding of Lotus corniculatus L. (2n=4x=24).

    PubMed

    Negri, V; Veronesi, F

    1989-09-01

    Crosses between male sterile L. corniculatus (2n=4x=24) and L. tenuis (2n=2x=12) plants were performed in order to verify the presence of 2n gametes in L. tenuis. All but one of the plants from these crosses had 2n=4x=24 and the L. corniculatus phenotype; this plant had 2n=2x=12 and the L. tenuis phenotype. The plants also showed good quantity of pollen at tripping, good pollen fertility and good percentage of seed setting in the backcross to L. corniculatus. On the whole, both cytological and morphological observations, showing that all but one of the plants from L. corniculatus x L. tenuis were normal tetraploids, suggest the existence of diploandrous gametes in L. tenuis. On the other hand, haploid parthenogenesis probably gave origin to the dihaploid plant 2n=2x=12.

  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

    2014-01-17

    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.

  7. 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

  8. 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

  9. 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.

  10. The Specification and Global Reprogramming of Histone Epigenetic Marks during Gamete Formation and Early Embryo Development in C. elegans

    PubMed Central

    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.

    2014-01-01

    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

  11. 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.

  12. Erratic male meiosis resulting in 2n pollen grain formation in a 4x cytotype (2n = 28) of Ranunculus laetus Wall. ex Royle.

    PubMed

    Kumar, Puneet; Singhal, Vijay Kumar

    2012-01-01

    Two accessions were studied for male meiosis in Ranunculus laetus from the cold regions of Northwest Himalayas. One accession showed the presence of 14 bivalents at diakinesis and regular segregation of bivalents at anaphase I which lead to normal tetrad formation with four n microspores and consequently n pollen grains and 100% pollen fertility. Second accession from the same locality revealed the erratic meiosis characterized by the presence of all the 28 chromosomes as univalents in meiocytes at metaphase I. Univalent chromosomes failed to segregate during anaphases and produced restitution nuclei at meiosis I and II. These restitution nuclei resulted into dyads and triads which subsequently produced two types of apparently fertile pollen grains. On the basis of size, the two types of pollen grains were categorized as n (normal reduced) and 2n (unreduced, 1.5-times larger than the n pollen grains). The estimated frequency of 2n pollen grains from dyads and triads (61.59%) was almost the same as that of the observed one (59.90%), which indicated that 2n pollen grains in R. laetus were the result of dyads and triads. The present paper herein may provide an insight into the mechanisms of the formation of various intraspecific polyploids through sexual polyploidization in R. laetus.

  13. 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...

  14. Electronic structure, stability, and formation dynamics of hypervalent molecular clusters: CH 3NH 3(CH 3NH 2) n

    NASA Astrophysics Data System (ADS)

    Okai, Nobuhiro; Takahata, Akihiro; Fuke, Kiyokazu

    2004-03-01

    The formation and decay processes of CH 3NH 3(CH 3NH 2) n produced by the photolysis of (CH 3NH 2) n are studied by a pump-probe technique with femtosecond laser. The dissociation time of CH 3NH 2 in clusters is estimated to be less than 500 fs, while the formation time of CH 3NH 3(CH 3NH 2) n is less than 2 ps in the photolysis at 200 nm. The lifetime of free CH 3NH 3 is determined to be 30 ps and is elongated by 10 5 times in clusters. The ionization potentials and the binding energies of these clusters are determined by photoionization threshold measurements. On the basis of these results, the formation and decay processes for these clusters are discussed.

  15. Proteomic Analysis of the Low Mutation Rate of Diploid Male Gametes Induced by Colchicine in Ginkgo biloba L.

    PubMed Central

    Yang, Nina; Sun, Yuhan; Wang, Yaru; Long, Cui; Li, Yingyue; Li, Yun

    2013-01-01

    Colchicine treatment of G. biloba microsporocytes results in a low mutation rate in the diploid (2n) male gamete. The mutation rate is significantly lower as compared to other tree species and impedes the breeding of new economic varieties. Proteomic analysis was done to identify the proteins that influence the process of 2n gamete formation in G. biloba. The microsporangia of G. biloba were treated with colchicine solution for 48 h and the proteins were analyzed using 2-D gel electrophoresis and compared to protein profiles of untreated microsporangia. A total of 66 proteins showed difference in expression levels. Twenty-seven of these proteins were identified by mass spectrometry. Among the 27 proteins, 14 were found to be up-regulated and the rest 13 were down-regulated. The identified proteins belonged to five different functional classes: ATP generation, transport and carbohydrate metabolism; protein metabolism; ROS scavenging and detoxifying enzymes; cell wall remodeling and metabolism; transcription, cell cycle and signal transduction. The identification of these differentially expressed proteins and their function could help in analysing the mechanism of lower mutation rate of diploid male gamete when the microsporangium of G. biloba was induced by colchicine. PMID:24167543

  16. Formation mechanisms of Si3N4 and Si2N2O in silicon powder nitridation

    NASA Astrophysics Data System (ADS)

    Yao, Guisheng; Li, Yong; Jiang, Peng; Jin, Xiuming; Long, Menglong; Qin, Haixia; Kumar, R. Vasant

    2017-04-01

    Commercial silicon powders are nitrided at constant temperatures (1453 K; 1513 K; 1633 K; 1693 K). The X-ray diffraction results show that small amounts of Si3N4 and Si2N2O are formed as the nitridation products in the samples. Fibroid and short columnar Si3N4 are detected in the samples. The formation mechanisms of Si3N4 and Si2N2O are analyzed. During the initial stage of silicon powder nitridation, Si on the outside of sample captures slight amount of O2 in N2 atmosphere, forming a thin film of SiO2 on the surface which seals the residual silicon inside. And the oxygen partial pressure between the SiO2 film and free silicon is decreasing gradually, so passive oxidation transforms to active oxidation and metastable SiO(g) is produced. When the SiO(g) partial pressure is high enough, the SiO2 film will crack, and N2 is infiltrated into the central section of the sample through cracks, generating Si2N2O and short columnar Si3N4 in situ. At the same time, metastable SiO(g) reacts with N2 and form fibroid Si3N4. In the regions where the oxygen partial pressure is high, Si3N4 is oxidized into Si2N2O.

  17. 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.

  18. Will artificial gametes end infertility?

    PubMed

    Smajdor, Anna; Cutas, Daniela

    2015-06-01

    In this paper we will look at the various ways in which infertility can be understood and at how need for reproductive therapies can be construed. We will do this against the background of research with artificial gametes (AGs). Having explored these questions we will attempt to establish the degree to which technologies such as AGs could expand the array of choices that people have to reproduce and/or become parents. Finally, we will examine whether and in what ways the most promising developments of such technologies are likely to bring about the "end of infertility".

  19. 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

  20. Inbreeding depression in male gametic performance.

    PubMed

    Losdat, S; Chang, S-M; Reid, J M

    2014-06-01

    One key objective in evolutionary ecology is to understand the magnitude of inbreeding depression expressed across sex-specific components of fitness. One major component of male fitness is fertilization success, which depends on male gametic performance (sperm and pollen performance in animals and plants, respectively). Inbreeding depression in male gametic performance could create sex-specific inbreeding depression in fitness, increase the benefit of inbreeding avoidance and reduce the efficacy of artificial insemination and pollination. However, there has been no assessment of the degree to which inbreeding generally depresses male gametic performance and hence post-copulatory or post-pollination fertilization success. Because inbreeding depression is understood to be a property of diploid entities, it is not clear what degree of inbreeding depression in haploid gametic performance should be expected. Here, we first summarize how inbreeding depression in male gametic performance could potentially arise through gene expression in associated diploid cells and/or reduced genetic diversity among haploid gametes. We then review published studies that estimate the magnitude of inbreeding depression in traits measuring components of sperm or pollen quantity, quality and competitiveness. Across 51 published studies covering 183 study traits, the grand mean inbreeding load was approximately one haploid lethal equivalent, suggesting that inbreeding depresses male gametic performance across diverse systems and traits. However, there was an almost complete lack of explicit estimates from wild populations. Future studies should quantify inbreeding depression in systematic sets of gametic traits under naturally competitive and noncompetitive conditions and quantify the degree to which gamete phenotypes and performance reflect haploid vs. diploid gene expression.

  1. Intra-Family Gamete Donation: A Solution to Concerns Regarding Gamete Donation in China?

    PubMed

    Liao, Juhong; Devolder, Katrien

    2016-09-01

    Gamete donation from third parties is controversial in China as it severs blood ties, which are considered of utmost importance in Confucian tradition. In recent years, infertile couples are increasingly demonstrating a preference for the use of gametes donated by family members to conceive children-known as "intra-family gamete donation." The main advantage of intra-family gamete donation is that it maintains blood ties between children and both parents. To date there is no practice of intra-family gamete donation in China. In this paper, we investigate intra-family adoption in China in order to illustrate that intra-family gamete donation is consistent with Confucian tradition regarding the importance of maintaining blood ties within the family. There are several specific ethical issues raised by intra-family gamete donation. It may, for example, result in consanguinity and the semblance of incest, lead to confused family relationships, and raise concerns about possible coercion of familial donors. Confucian tradition provides a new approach to understand and deal with these ethical issues in a way that Western tradition does not. As a result, we suggest intra-family gamete donation could be an acceptable solution to the problem of infertility in China. However, further discussion and open debates on the ethical issues raised by intra-family gamete donation are needed in China.

  2. 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.

  3. Refrigeration of rainbow trout gametes and embryos.

    PubMed

    Babiak, Igor; Dabrowski, Konrad

    2003-12-01

    Prolonged access to early embryos composed of undifferentiated, totipotent blastomeres is desirable in situations when multiple collections of gametes are not possible. The objective of the present study is to examine whether the refrigeration of rainbow trout Oncorhynchus mykiss gametes and early embryos would be a suitable, reliable, and efficient tool for prolonging the availability of early developmental stages up to the advanced blastula stage. The study was conducted continuously during fall, winter, and spring spawning seasons. In all, more than 500 experimental variants were performed involving individual samples from 26 females and 33 males derived from three strains. These strains represented three possible circumstances. In optimal one, gametes from good quality donors were obtained soon after ovulation. In the two non-optimal sources, either donors were of poor genetic quality or gametes were collected from a distant location and transported as unfertilized gametes. A highly significant effect of variability of individual sample quality on efficiency of gamete and embryo refrigeration was revealed. The source of gametes significantly affected viability of refrigerated oocytes and embryos, but not spermatozoa. On average, oocytes from optimal source retained full fertilization viability for seven days of chilled storage, significantly longer than from non-optimal sources. Spermatozoa, regardless of storage method, retained full fertilization ability for the first week of storage. Refrigeration of embryos at 1.4+/-0.4 degrees C significantly slowed the development. Two- week-old embryos were still in blastula stage. Average survival rate of embryos refrigerated for 10 days and then transferred to regular incubation temperatures of 9-14 degrees C was 92% in optimal and 51 and 71% in non-optimal source variants. No effect of gamete and embryo refrigeration on the occurrence of developmental abnormalities was observed. Cumulative refrigeration of oocytes and

  4. 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

  5. PHYSICAL PROPERTIES OF GAMETES IN THREE SEA URCHIN SPECIES

    PubMed

    Thomas

    1994-09-01

    Physical properties (density in kg m-3, viscosity, sinking rates and dispersion rate) of the gametes and associated spawned materials were measured for three species of sea urchin, Tripneustes gratilla, Echinometra mathaei and Colobocentrotus atratus, from habitats that differ in wave exposure. The gametes of all three species are negatively buoyant, highly viscous and exhibit shear-thinning (a decrease in viscosity with increasing shear rate). Female gametes are more viscous than male gametes, and the viscosity of female gametes differs among the three species. The viscosity of female gametes is highest for C. atratus, the species from habitats most exposed to wave action. Within the species T. gratilla, viscosity of female gametes is higher in habitats exposed to wave action than in more protected habitats. Evidence reported in this paper suggests that the shear-thinning of gametes may provide a performance advantage for these sea urchins. High viscosity of gametes at low shear rates may decrease gamete dispersal upon release and, under certain flow conditions, allow gametes to form strings and clumps on the surface of the urchin. Depending upon the morphology of the surface, these clumps or strings may be retained and fertilization may occur within these clumps or strings. Conversely, low viscosity of gametes at high shear rates decreases the power required to extrude gametes through the gonoduct during spawning.

  6. Negotiating boundaries: Accessing donor gametes in India

    PubMed Central

    Widge, A.; Cleland, J.

    2011-01-01

    Background: This paper documents how couples and providers access donor materials for conception in the Indian context and perceptions about using them. The objective is to facilitate understanding of critical issues and relevant concerns. Methods: A postal survey was conducted with a sample of 6000 gynaecologists and in-depth interviews were conducted with 39 gynaecologists in four cities. Results: Donor gametes are relatively more acceptable than a few years ago, especially if confidentiality can be maintained, though lack of availability of donor materials is sometimes an impediment to infertility treatment. Donor sperms are usually accessed from in-house or commercial sperm banks, pathology laboratories, IVF centres, professional donors, relatives or friends. There is scepticism about screening procedures of sperm banks. Donor eggs are usually accessed from voluntary donors, friends, relatives, egg sharing programmes, donation from other patients, advertising and commercial donors. There are several concerns regarding informed consent for using donated gametes, using relatives and friends gametes, the unregulated use of gametes and embryos, record keeping and documentation, unethical and corrupt practices and commercialisation. Conclusion: These issues need to be addressed by patients, providers and regulatory authorities by providing information, counselling, ensuring informed consent, addressing exploitation and commercialisation, ensuring monitoring, proper documentation and transparency. PMID:24753849

  7. 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; ...

    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

  8. [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.

  9. Male gamete biology in flowering plants.

    PubMed

    Russell, Scott D; Gou, Xiaoping; Wei, Xiaoping; Yuan, Tong

    2010-04-01

    Flowering plant reproduction is characterized by double fertilization, in which two diminutive brother sperm cells initiate embryo and endosperm. The role of the male gamete, although studied structurally for over a century at various levels, is still being explored on a molecular and cellular level. The potential of the male to influence development has been historically underestimated and the reasons for this are obvious: limitations provided by maternal imprinting, the much greater cellular volume of female gametes and the general paucity of paternal effects. However, as more is known about molecular expression of chromatin-modifying proteins, ubiquitin pathway proteins and transcription factors in sperm cells, as well as their ability to achieve effect by intaglio expression, passing transcripts directly into translation, the role of the male is likely to expand. Much of the expression in the male germline that appears to be distinct from patterns of pollen vegetative cell expression may be the result of chromosomal level regulation of transcription.

  10. Of stem cells and gametes: similarities and differences.

    PubMed

    Roelen, Bernard A J; Lopes, Susana M Chuva de Sousa

    2008-01-01

    Fusion of a mammalian sperm cell with an oocyte will lead to the formation of a new organism. As this new organism develops, the cells that construct the organism gradually lose developmental competence and become differentiated, a process which is in part mediated via epigenetic modifications. These mechanisms include DNA methylation, histone tail modifications and association with Polycomb and Trithorax proteins. Several cells within the organism must however maintain or regain developmental competence while they are highly specialized. These are the primordial germ cells that form the gametes; the oocytes and sperm cells. In this review different epigenetic modifying mechanisms will be discussed as they occur in developing embryos. In addition, aspects of nuclear reprogramming that are likely to occur via removal of epigenetic modifications are important, and several epigenetic removal mechanisms are indeed also active in developing germ cells. In vivo, a pluripotent cell has the capacity to form gametes, but in vitro terminal gametogenesis has proven to be difficult. Although development of pluripotent cells to cells with the characteristics of early germ cells has been unequivocally demonstrated, creating the correct culture milieu that enables further maturation of these cells has as yet been futile.

  11. Production of Polyploids and Unreduced Gametes in Lilium auratum × L. henryi Hybrid

    PubMed Central

    Chung, Mi-Young; Chung, Jae-Dong; Ramanna, Munikote; van Tuyl, Jaap M.; Lim, Ki-Byung

    2013-01-01

    Intergenomic F1 hybrids between L. auratum x L. henryi and their BC1 progeny were investigated through genomic in situ hybridization technique (GISH) to determine their potential value in lily breeding. We confirmed that F1 intergenomic hybrids possessed a set of chromosomes (x=12) from both parents and that flowers of the F1 auratum × henryi hybrid showed an intermediate morphological phenotype. Pollen size, viability and germination ability were measured through microscopic observations. F1 intergenomic hybrids produced a relevant frequency of 2n-gametes, which were successfully used to perform crosses with Oriental hybrids, resulting in the triploid Oriental Auratum Henryi (OAuH) hybrid. Twenty BC1 plants were generated by crossing between four different Oriental hybrid cultivars and F1 AuH hybrids using an in vitro embryo rescue technique, after which the genome constitution and chromosome composition were analyzed by GISH. All plants were triploid, showing 12 from female parents (diploid Oriental hybrid) and 24 from male parents (diploid F1 AuH hybrid). Overall, 16 out of 20 BC1 progeny possessed recombinant chromosomes with 1-5 crossover sites per plant. Cytological analysis of 20 BC1 plants by GISH verified that the occurrence of 2n pollen formation in all F1 AuH hybrids was derived from the FDR (first division restitution) mechanism, in which the genome composition of all BC1 plants possess 12 Oriental + 12 L. auratum + 12 L. henryi chromosomes. Allotriploids derived from the AuH hybrid were used as female for crossing with the diploid Oriental hybrid cultivar 'Sorbonne' and considerable numbers of plants (0-6.5 plants per ovary) were only obtained when female OAuH (BC1) triploids were used. Taken together, the results of this study indicate that production and analysis of F1 AuH hybrids and their progeny through sexual polyploidization can be useful for efficient creation of important horticultural traits. PMID:23904793

  12. Balancing Ethical Pros and Cons of Stem Cell Derived Gametes.

    PubMed

    Segers, Seppe; Mertes, Heidi; de Wert, Guido; Dondorp, Wybo; Pennings, Guido

    2017-01-13

    In this review we aim to provide an overview of the most important ethical pros and cons of stem cell derived gametes (SCD-gametes), as a contribution to the debate about reproductive tissue engineering. Derivation of gametes from stem cells holds promising applications both for research and for clinical use in assisted reproduction. We explore the ethical issues connected to gametes derived from embryonic stem cells (both patient specific and non-patient specific) as well as those related to gametes derived from induced pluripotent stem cells. The technology of SCD-gametes raises moral concerns of how reproductive autonomy relates to issues of embryo destruction, safety, access, and applications beyond clinical infertility.

  13. 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.

  14. Let's get physical: gamete interaction in flowering plants.

    PubMed

    Sprunck, Stefanie

    2010-04-01

    Fertilization comprises a series of precisely orchestrated steps that culminate in the fusion of male and female gametes. The most intimate steps during fertilization encompass gamete recognition, adhesion and fusion. In animals, some binding-effector proteins and enzymes have been identified that act on the cell surfaces of the gametes to regulate gamete compatibility and fertilization success. In contrast, exploring plant gamete interaction during double fertilization, a characteristic trait of flowering plants, has been hampered for a long time because of the protected location of the female gametes and technical limitations. Over the last couple of years, however, the use of advanced methodologies, new imaging tools and new mutants has provided deeper insights into double fertilization, at both the cellular and the molecular level, especially for the model plant Arabidopsis thaliana. Most likely, one consequence of inventing double fertilization may be the co-evolution of special molecular mechanisms to govern each successful sperm delivery and efficient gamete recognition and fusion. In vivo imaging of double fertilization and the recent discovery of numerous female-gametophyte-specific expressed genes encoding small secreted proteins, some of whom were found to be essential for the fertilization process, support this hypothesis. Nevertheless, recent findings indicate that at least the membrane-merger step in plant gamete interaction may rely on an ancient and widely used gamete fusion system.

  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. Donor identification 'kills gamete donation'? A response.

    PubMed

    Allan, Sonia

    2012-12-01

    Two Australian government inquiries have recently called for the release of information to donor-conceived people about their gamete donors. A national inquiry, recommended 'as a matter of priority' that uniform legislation to be passed nationwide. A state-based inquiry argued that all donor-conceived people should have access to information and called for the enactment of retrospective legislation that would override donor anonymity. This paper responds to an opinion piece published in Human Reproduction in October 2012 by Professor Pennings in which he criticized such recommendations and questioned the motives of people that advocate for information release. I answer the arguments of Pennings, and argue that all parties affected by donor conception should be considered, and a compromise reached. The contact veto system is one such compromise. I discuss the education and support services recommended by the Victorian government and question Pennings' assertions that legislation enabling information release will lead to a decrease in gamete donation. Finally, I rebut Pennings' assertion that there is a 'hidden agenda' behind the call for information release. There is no such agenda in my work. If there is from others, then it is their discriminatory views that need to be addressed, not the move toward openness and honesty or the call for information by donor-conceived people.

  17. 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

  18. 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.

  19. Methods used to improve gamete efficiency.

    PubMed

    Marrs, R P; Serafini, P C; Kerin, J F; Batzofin, J; Stone, B A; Brown, J; Wilson, L; Quinn, P

    1988-01-01

    Male factor infertility accounts for a significant percentage of problems in infertile couples. With clinical utilization of the technologies for selection of good-quality spermatozoa from the ejaculate, our ability to successfully treat the severely affected male factor couple has improved. However, it must be remembered that even with current technologies, fertilization success is reduced in these patients but remains above a 50% level. Other factors that can be used in the future to improve on these statistics are being investigated in regard to the in vitro environment for gametes, that is, the type of culture medium, the methods of coincubation of the sperm and egg, and other methods of enhancement of sperm fertilizing potential. However, methods of sperm preparation will achieve improvement in a percentage of these males treated, and can be used to improve fertilization and pregnancy success. It is important to understand the limitations of the zona-free hamster test, but it is also important to use that test as a screening method for sperm handling. By utilizing the SPA to select out the optimal method of sperm preparation, the fertilization and pregnancy outcome can be improved. Overall, the live-birth rate in male factor infertile couples is lower than non-male-factor couples treated by IVF and GIFT. Until more is known about basic spermatozoal function, and the ability to improve that function in affected males, the live-birth rate should not be expected to change substantially.

  20. Mate choice among yeast gametes can purge deleterious mutations.

    PubMed

    Tazzyman, S J; Seymour, R M; Pomiankowski, A; Greig, D

    2012-08-01

    Meiosis in Saccharomyces yeast produces four haploid gametes that usually fuse with each other, an extreme form of self-fertilization among the products of a single meiosis known as automixis. The gametes signal to each other with sex pheromone. Better-quality gametes produce stronger signals and are preferred as mates. We suggest that the function of this signalling system is to enable mate choice among the four gametes from a single meiosis and so to promote the clearance of deleterious mutations. To support this claim, we construct a mathematical model that shows that signalling during automixis (i) improves the long-term fitness of a yeast colony and (ii) lowers its mutational load. We also show that the benefit to signalling is greater with larger numbers of segregating mutations.

  1. 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... for live fish, fertilized eggs, and gametes. (a) For all live fish, fertilized eggs, and gametes... fish, fertilized eggs, or gametes, the number, species, and the purpose of the importation, the name...

  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... for live fish, fertilized eggs, and gametes. (a) For all live fish, fertilized eggs, and gametes... fish, fertilized eggs, or gametes, the number, species, and the purpose of the importation, the name...

  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... for live fish, fertilized eggs, and gametes. (a) For all live fish, fertilized eggs, and gametes... fish, fertilized eggs, or gametes, the number, species, and the purpose of the importation, the name...

  4. 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... for live fish, fertilized eggs, and gametes. (a) For all live fish, fertilized eggs, and gametes... fish, fertilized eggs, or gametes, the number, species, and the purpose of the importation, the name...

  5. 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.

  6. 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.

  7. In Vitro Fertilization with Isolated, Single Gametes Results in Zygotic Embryogenesis and Fertile Maize Plants.

    PubMed Central

    Kranz, E; Lorz, H

    1993-01-01

    We demonstrate here the possibility of regenerating phenotypically normal, fertile maize plants via in vitro fertilization of isolated, single sperm and egg cells mediated by electrofusion. The technique leads to the highly efficient formation of polar zygotes, globular structures, proembryos, and transition-phase embryos and to the formation of plants from individually cultured fusion products. Regeneration of plants occurs via embryogenesis and occasionally by polyembryony and organogenesis. Flowering plants can be obtained within 100 days of gamete fusion. Regenerated plants were studied by karyological and morphological analyses, and the segregation of kernel color was determined. The hybrid nature of the plants was confirmed. PMID:12271084

  8. [Features of the formation of self-fertile euploid lines (2n = 42) by self-pollination of the 46-chromosome barley-wheat BC1 hybrid Hordeum marinum subsp. gussoneanum Hudson (= H. geniculatum All.) (2n = 28) x Triticum aestivum L. (2n = 42)].

    PubMed

    Pershina, L A; Trubacheeva, N V; Rakovtseva, T S; Belova, L I; Deviatkina, E P; Kravtsova, L A

    2006-12-01

    We studied some features of the development of self-fertile 42-chromosome lines on the base of self-pollination progeny of 46-chromosome plants obtained by backcrossing of barley--wheat hybrids Hordeum marinum subsp. gussoneanum Hudson (= H. geniculatum All.) (2n = 28) x Triticum aestivum L. (2n = 42). The stabilization of karyotypes, resulting in 42-chromosome plants of the wheat type was generally completed by generation BC1F10. The plants of all self-pollination progenies, including BC1F10, showed some phenotypic traits characteristic of wild barley. Plants of BC1F10 with the chromosome sets 2n = 42 and 2n = 42 + t were analyzed by RAPD with a set of 115 primers. Fragments of the wild barley genome were detected in RAPD patterns with 19 primers. Cross-hybridization confirmed that these fragments belonged to the wild barley genome. We raised four phenotypically different 42-chromosome lines from grains obtained from plants of generation BC1F10, and these lines proved to be cytogenetically stable and self-fertile when grown in the field.

  9. The Genic Nature of Gamete Eliminator in Rice

    PubMed Central

    Sano, Y.

    1990-01-01

    The two cultivated rice species, Oryza sativa and Oryza glaberrima, are morphologically alike but are reproductively isolated from each other by hybrid sterility. The hybrid is male sterile but partially female fertile. Backcross experiments were conducted to introduce an alien factor controlling hybrid sterility from O. glaberrima (W025) into O. sativa (T65wx) and examine the genetic basis. An extracted sterility factor, closely linked to the wx locus, induced gametic abortion due to allelic interaction and was tentatively designated as S((t)). The segregation patterns for infertility was explained by assuming that W025 and T65wx carried S((t)) and S((t))(a), respectively, and gametes with S((t))(a) aborted only in the heterozygote (S((t))/S((t))(a)) although the elimination of female gametes was incomplete. Thus, S((t)) seemed to be intermediate between a gamete eliminator and pollen killer. However, S((t)) was proven to be likely the same as S(1) which was formerly reported as gamete eliminator in a different genetic background of O. sativa. In addition, a chromosomal segment containing S(1) (or S((t))) caused a marked suppression of crossing over around it, suggesting the presence of an inversion. Further, female transmission of S(1)(a) increased as the segment containing S(1) became small by recombination. After S(1) was further purified by successive backcrosses up to the BC(15) generation, it became pollen killer. The present results give evidence that a profound sterility gene such as gamete eliminator can be made from accumulation of pollen killer and its modifier(s) when pollen killer and modifier(s) are linked, they behave as a gene complex in the hybrid. PMID:2341030

  10. 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.

  11. 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

  12. Gamete and embryo-fetal origins of adult diseases.

    PubMed

    Monti, Manuela

    2016-08-10

    By putting together the most advanced evidences supporting the 'gamete and embryo-fetal origins of adult diseases' the two editors, Prof. He-Feng Huang and Prof. Jian-Zhong Sheng (Hangzhou, People's Republic of China) did a great workk.....

  13. Formation of SiN Films by Plazma-Enhanced Chemical Vapor Deposition Using [(CH3)2N]3SiN3

    NASA Astrophysics Data System (ADS)

    Kitoh, Hideyuki; Muroyama, Masakazu

    1994-12-01

    An organic source gas, tris-dimethyl-amino-silyl-azide (TDSA, [(CH3)2N]3SiN3), was newly synthesized and utilized for the deposition of a passivation film of sub-half-micrometer devices. Deposition temperature dependence of the film formed by plasma-enhanced chemical vapor deposition (PECVD) using TDSA was investigated and step coverage of the TDSA film was examined. As a result, it was clarified that hydrocarbon content in the film decreased with increasing deposition temperature. The bottom step coverage of the films formed using TDSA was greatly improved compared to that of the conventional silicon nitride film.

  14. 9 CFR 93.903 - Import permits for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., fertilized eggs, and gametes. 93.903 Section 93.903 Animals and Animal Products ANIMAL AND PLANT HEALTH... General Provisions for Svc-Regulated Fish Species § 93.903 Import permits for live fish, fertilized eggs, and gametes. (a) Live fish, fertilized eggs, or gametes of SVC-susceptible species imported into...

  15. 9 CFR 93.903 - Import permits for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., fertilized eggs, and gametes. 93.903 Section 93.903 Animals and Animal Products ANIMAL AND PLANT HEALTH... General Provisions for Svc-Regulated Fish Species § 93.903 Import permits for live fish, fertilized eggs, and gametes. (a) Live fish, fertilized eggs, or gametes of SVC-susceptible species imported into...

  16. 9 CFR 93.903 - Import permits for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., fertilized eggs, and gametes. 93.903 Section 93.903 Animals and Animal Products ANIMAL AND PLANT HEALTH... General Provisions for Svc-Regulated Fish Species § 93.903 Import permits for live fish, fertilized eggs, and gametes. (a) Live fish, fertilized eggs, or gametes of SVC-susceptible species imported into...

  17. 9 CFR 93.903 - Import permits for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., fertilized eggs, and gametes. 93.903 Section 93.903 Animals and Animal Products ANIMAL AND PLANT HEALTH... General Provisions for Svc-Regulated Fish Species § 93.903 Import permits for live fish, fertilized eggs, and gametes. (a) Live fish, fertilized eggs, or gametes of SVC-susceptible species imported into...

  18. Gametophytic Pollen Tube Guidance: Attractant Peptides, Gametic Controls, and Receptors.

    PubMed

    Higashiyama, Tetsuya; Yang, Wei-Cai

    2017-01-01

    Pollen tube guidance in flowering plants is a unique and critical process for successful sexual reproduction. The pollen tube that grows from pollen, which is the male gametophyte, precisely navigates to the embryo sac, which is the female gametophyte, within the pistil. Recent advances have clarified the molecular framework of gametophytic pollen tube guidance. Multiple species-specific attractant peptides are secreted from synergid cells, the proper development and function of which are regulated by female gametes. Multiple receptor-like kinases on the pollen tube tip are involved in sensing species-specific attractant peptides. In this Update article, recent progress in our understanding of the mechanism of gametophytic pollen tube guidance is reviewed, including attraction by synergid cells, control of pollen tube guidance by female gametes, and directional growth of the pollen tube by directional cue sensing. Future directions in the study of pollen tube guidance also are discussed.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. Defect formation in layered ionic crystals of (CnH2n+1NH3)2MCl4:M=Cd, Cu, Mn;n=1,2,3 and CsMnCl3-2H20

    NASA Astrophysics Data System (ADS)

    Yoshinari, Takehisa; Matsuyama, Tomochika; Shimanuki, Shigetaka; Nanba, Takao; Fujisawa, Masami; Yamaoka, Hitoshi; Kamikawa, Tomoyoshi; Aoyagi, Kiyoshi

    1995-02-01

    Metal precipitation has been observed at the 2D crystals of alkylammonium metal chlorides, (CnH2n+1NH3)2MCl4 which were X- or (gamma) -irradiated at 77 K and warmed to room temperature. It has been also observed in the 1D crystals of CsMnCl3(DOT)2H2O which was irradiated at room temperature similar as photochromism of silver halides. The different temperature conditions of metal precipitation suggest a variety of defect formation mechanisms. In alkylammonium metal chlorides, Cl2- molecule ions are formed at 77 K and electron trap centers are observed at 15 K with X-ray irradiation. The electron trap centers are very unstable and are bleached at temperatures higher than 30 K.

  7. 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.

  8. DNA damage response in male gametes of Cyrtanthus mackenii during pollen tube growth

    PubMed Central

    Hirano, Tomonari; Takagi, Keiichi; Hoshino, Yoichiro; Abe, Tomoko

    2013-01-01

    Male gametophytes of plants are exposed to environmental stress and mutagenic agents during the double fertilization process and therefore need to repair the DNA damage in order to transmit the genomic information to the next generation. However, the DNA damage response in male gametes is still unclear. In the present study, we analysed the response to DNA damage in the generative cells of Cyrtanthus mackenii during pollen tube growth. A carbon ion beam, which can induce DNA double-strand breaks (DSBs), was used to irradiate the bicellular pollen, and then the irradiated pollen grains were cultured in a liquid culture medium. The male gametes were isolated from the cultured pollen tubes and used for immunofluorescence analysis. Although inhibitory effects on pollen tube growth were not observed after irradiation, sperm cell formation decreased significantly after high-dose irradiation. After high-dose irradiation, the cell cycle progression of generative cells was arrested at metaphase in pollen mitosis II, and phosphorylated H2AX (γH2AX) foci, an indicator of DSBs, were detected in the majority of the arrested cells. However, these foci were not detected in cells that were past metaphase. Cell cycle progression in irradiated generative cells is regulated by the spindle assembly checkpoint, and modification of the histones surrounding the DSBs was confirmed. These results indicate that during pollen tube growth generative cells can recognize and manage genomic lesions using DNA damage response pathways. In addition, the number of generative cells with γH2AX foci decreased with culture prolongation, suggesting that the DSBs in the generative cells are repaired. PMID:23550213

  9. The structure, stability, and infrared spectrum of B 2N, B 2N +, B 2N -, BO, B 2O and B 2N 2.

    NASA Astrophysics Data System (ADS)

    Martin, J. M. L.; François, J. P.; Gijbels, R.

    1992-05-01

    The structure, infrared spectrum, and heat of formation of B 2N, B 2N -, BO, and B 2O have been studied ab initio. B 2N is very stable; B 2O even more so. B 2N, B 2N -, B 2O, and probably B 2N + have symmetric linear ground-state structures; for B 2O, an asymmetric linear structure lies about 12 kcal/mol above the ground state. B 2N +, B 2N - and B 2O have intense asymmetric stretching frequencies, predicted near 870, 1590 and 1400 cm -1, respectively. Our predicted harmonic frequencies and isotopic shifts for B 2O confirm the recent experimental identification by Andrews and Burkholder. Absorptions at 1889.5 and 1998.5 cm -1 in noble-gas trapped boron nitride vapor belong the BNB and BNBN ( 3Π), respectively; a tentative assignment of 882.5 cm -1 to BNB + is proposed. Total atomization energies Σ De (Σ D0) are computed (accuracy ±2 kcal/mol) as: BO 193.1 (190.4), B 2O 292.5 (288.7), B 2N 225.0 (250.3) kcal/mol. The ionization potential and electron affinity of B 2N are predicted to be 8.62±0.1 and 3.34±0.1 eV. The MP4-level additivity approximations involved in G1 theory results in errors on the order of 1 kcal/mol in the Σ De values.

  10. Transcriptomes of isolated Oryza sativa gametes characterized by deep sequencing: evidence for distinct sex-dependent chromatin and epigenetic states before fertilization.

    PubMed

    Anderson, Sarah N; Johnson, Cameron S; Jones, Daniel S; Conrad, Liza J; Gou, Xiaoping; Russell, Scott D; Sundaresan, Venkatesan

    2013-12-01

    The formation of a zygote by the fusion of egg and sperm involves the two gametic transcriptomes. In flowering plants, the embryo sac embedded within the ovule contains the egg cell, whereas the pollen grain contains two sperm cells inside a supporting vegetative cell. The difficulties of collecting isolated gametes and consequent low recovery of RNA have restricted in-depth analysis of gametic transcriptomes in flowering plants. We isolated living egg cells, sperm cells and pollen vegetative cells from Oryza sativa (rice), and identified transcripts for approximately 36 000 genes by deep sequencing. The three transcriptomes are highly divergent, with about three-quarters of those genes differentially expressed in the different cell types. Distinctive expression profiles were observed for genes involved in chromatin conformation, including an unexpected expression in the sperm cell of genes associated with active chromatin. Furthermore, both the sperm cell and the pollen vegetative cell were deficient in expression of key RNAi components. Differences in gene expression were also observed for genes for hormonal signaling and cell cycle regulation. The egg cell and sperm cell transcriptomes reveal major differences in gene expression to be resolved in the zygote, including pathways affecting chromatin configuration, hormones and cell cycle. The sex-specific differences in the expression of RNAi components suggest that epigenetic silencing in the zygote might act predominantly through female-dependent pathways. More generally, this study provides a detailed gene expression landscape for flowering plant gametes, enabling the identification of specific gametic functions, and their contributions to zygote and seed development.

  11. Microfluidics for gametes, embryos, and embryonic stem cells.

    PubMed

    Smith, G D; Swain, J E; Bormann, C L

    2011-01-01

    Microfluidics is a young but established field that holds significant potential for scientific discovery. The utility of microfluidics can improve our knowledge of basic biology as well as expand our understanding in specialized areas such as assisted reproduction and stem cell developmental biology. This review describes the technology of microfluidics and discusses applications within assisted reproduction technology and embryonic stem cell growth and directed differentiation. Development of an integrated microfluidic platform for assisted reproduction, which can manipulate gametes, embryos, embryonic stem cells, their culture environment, and incorporate biomarker analysis, could have a dramatic impact on the basic understanding of embryo/embryonic stem cell development, as well as provide significant improvements in current technologies used to treat infertility, preserve fertility, and derive therapeutic cells from stem cells.

  12. Flagellar tip activation stimulated by membrane adhesions in Chlamydomonas gametes

    PubMed Central

    1980-01-01

    Membrane adhesions between the flagella of mating-type "plus" and "minus" gametes of Chlamydomonas reinhardi are shown to stimulate a rapid change in the ultrastructure of the flagellar tips, designated as flagellar tip activation (FTA). A dense substance, termed fibrous tip material (FTM), accumulates between the flagellar membrane and the nine single A microtubules of the tip. The A microtubules then elongate, growing into the distal region of the tip, increasing tip length by 30%. This study describes FTA kinetics during normal and mutant matings, presents experiments designed to probe its role in the mating reaction, and offers the following conclusions: (a) FTA is elicited by agents that cross-link flagellar membrane components (including natural sexual agglutinins, antiflagellar antisera, and concanavalin A) but not by flagellar adherence to polylysine-coated films. (b) FTA is reversed by flagellar disadhesion. (c) Gametes can undergo repeated cycles of FTA during successive rounds of adhesion/disadhesion. (d) FTA, flagellar tipping, and sexual signaling are simultaneously blocked by colchicine and by vinblastine, suggesting that tubulinlike molecules, perhaps exposed at the membrane surface, are involved in all three responses. (e) FTA is not blocked by short exposure to chymotrypsin, by cytochalasins B and D, nor by concanavalin A, even though all block cell fusion; the response is therefore autonomous and experimentally dissociable from later stages in the mating reaction. (f) Under no experimental conditions is mating-structure activation observed to occur unless FTA also occurs. This study concludes that FTA is a necessary event in the sexual signaling sequence, and presents a testable working model for its mechanism. PMID:7358792

  13. 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

  14. 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... importation of live fish, fertilized eggs, and gametes. (a) The following ports are designated as ports of entry for live fish, fertilized eggs, and gametes of SVC-susceptible species imported under this...

  15. 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... importation of live fish, fertilized eggs, and gametes. (a) The following ports are designated as ports of entry for live fish, fertilized eggs, and gametes of SVC-susceptible species imported under this...

  16. Relative effects of gamete compatibility and hydrodynamics on fertilization in the green sea urchin Strongylocentrotus droebachiensis.

    PubMed

    Kregting, Louise T; Thomas, Florence I M; Bass, Anna L; Yund, Philip O

    2014-08-01

    Intraspecific variation in gamete compatibility among male/female pairs causes variation in the concentration of sperm required to achieve equivalent fertilization levels. Gamete compatibility is therefore potentially an important factor controlling mating success. Many broadcast-spawning marine invertebrates, however, also live in a dynamic environment where hydrodynamic conditions can affect the concentration of sperm reaching eggs during spawning. Thus flow conditions may moderate the effects of gamete compatibility on fertilization. Using the green sea urchin Strongylocentrotus droebachiensis as a model system, we assessed the relative effects of gamete compatibility (the concentration of sperm required to fertilize 50% of the eggs in specific male/female pairs; F50) and the root-mean-square of total velocity (urms; 0.01-0.11 m s(-1)) on fertilization in four locations near a spawning female (water column, wake eddy, substratum, and aboral surface) in both unidirectional and oscillatory flows. Percent fertilization decreased significantly with increasing urms at all locations and both flow regimes. However, although gamete compatibility varied by almost 1.5 orders of magnitude, it was not a significant predictor of fertilization for most combinations of position and flow. The notable exception was a significant effect of gamete compatibility on fertilization on the aboral surface under unidirectional flow. Our results suggest that selection on variation in gamete compatibility may be strongest in eggs fertilized on the aboral surface of sea urchins and that hydrodynamic conditions may add environmental noise to selection outcomes.

  17. 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.

  18. Microsatellite analyses of artificial and spontaneous dogrose hybrids reveal the hybridogenic origin of Rosa micrantha by the contribution of unreduced gametes.

    PubMed

    Ritz, Christiane M; Wissemann, Volker

    2011-01-01

    Dogroses are characterized by a unique meiosis system, the so-called canina meiosis, which facilitates sexual reproduction at odd-number ploidy. The mostly pentaploid somatic level of dogroses is restored by a merger of haploid sperm cells and tetraploid egg cells. We analyzed experimental hybrids between different dogrose species using microsatellites to determine pollen-transmitted alleles. This information was used to reconstruct the putative hybridogenic origin of Rosa micrantha and R. dumalis and to estimate the frequency of spontaneous hybridization in a natural population. We found no evidence for the hybrid origin of R. dumalis, but our data suggest that R. micrantha presumably arose by hybridization between R. rubiginosa and R. canina or R. corymbifera. We observed only hexaploid individuals of R. micrantha, thus the establishment of this hybridogenic species was favored when unreduced gametes contributed to their origin. We demonstrate that spontaneous hybrids originated infrequently from the parental species in a natural population, but hybridization was often associated with the formation of unreduced gametes. We postulate that unreduced gametes play a major role in the evolutionary success of dogrose hybrids because they provide highly homologous chromosomes crucial for bivalent formation during canina meiosis and thus ensuring this unique form of sexual reproduction.

  19. 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.

  20. 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.

  1. 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.

  2. Delayed childbearing: determining responsibilities for prime gamete quality.

    PubMed

    Campagne, Daniel M

    2013-01-01

    Delayed parenting affects fertility in women and in men, and cryopreservation of oocytes and sperm is becoming the latest trend as a solution for those who want or need to postpone procreation, in an attempt to avoid the damage medical conditions or time itself produces in gametes. Although "social freezing" is considered legitimate, its ethical and social aspects are in need of an overdue medical, public and legal debate. Assisted reproduction and cryopreservation, in combination with womb outsourcing, have opened the door to biological ectogenesis and the subsequent question of whether delayed childbearing means we should formally separate procreation from sexual activity. This article briefly summarizes what cryotechniques are capable of presently and in the near future, to separate fact from fiction. It names the implications for and discusses the practically virgin subject of the underlying responsibilities of delayed parenting techniques towards the child-to-be-not only the unborn but also the not-yet-conceived child. Considering the medical, economic, legal and social consequences of these rapidly growing developments in reproduction, several reasons point at the need to formally separate procreation from sexual activity, specifying responsibilities in the first while respecting personal choice in the second.

  3. [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.

  4. 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

  5. Natural hybridization in the sea urchin genus Pseudoboletia between species without apparent barriers to gamete recognition.

    PubMed

    Zigler, Kirk S; Byrne, Maria; Raff, Elizabeth C; Lessios, H A; Raff, Rudolf A

    2012-06-01

    Marine species with high dispersal potential often have huge ranges and minimal population structure. Combined with the paucity of geographic barriers in the oceans, this pattern raises the question as to how speciation occurs in the sea. Over the past 20 years, evidence has accumulated that marine speciation is often linked to the evolution of gamete recognition proteins. Rapid evolution of gamete recognition proteins in gastropods, bivalves, and sea urchins is correlated with gamete incompatibility and contributes to the maintenance of species boundaries between sympatric congeners. Here, we present a counterexample to this general pattern. The sea urchins Pseudoboletia indiana and P. maculata have broad ranges that overlap in the Indian and Pacific oceans. Cytochrome oxidase I sequences indicated that these species are distinct, and their 7.3% divergence suggests that they diverged at least 2 mya. Despite this, we suspected hybridization between them based on the presence of morphologically intermediate individuals in sympatric populations at Sydney, Australia. We assessed the opportunity for hybridization between the two species and found that (1) individuals of the two species occur within a meter of each other in nature, (2) they have overlapping annual reproductive cycles, and (3) their gametes cross-fertilize readily in the laboratory and in the field. We genotyped individuals with intermediate morphology and confirmed that many were hybrids. Hybrids were fertile, and some female hybrids had egg sizes intermediate between the two parental species. Consistent with their high level of gamete compatibility, there is minimal divergence between P. indiana and P. maculata in the gamete recognition protein bindin, with a single fixed amino acid difference between the two species. Pseudoboletia thus provides a well-characterized exception to the idea that broadcast spawning marine species living in sympatry develop and maintain species boundaries through the

  6. 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

  7. Debate in embryo donation: embryo donation or both-gamete donation?

    PubMed

    Samani, Reza Omani; Moalem, Mohammad Reza Rezania; Merghati, Seyed Taha; Alizadeh, Leila

    2009-01-01

    So far, more than 2 million babies have been born worldwide through assisted reproduction technologies. For many couples, there is no treatment except by involving a third party. Recently, embryo donation law has been approved by Iran's parliament and now it is legal in Iran. But there is a misunderstanding regarding the source of embryos: they can be obtained from surplus frozen embryos of infertile couples or embryos can be made from donated spermatozoa and eggs from fertile married couples. Here in this paper we discuss ethical, religious and legal aspects of these two procedures and present the advantages and disadvantages of them. Meanwhile, the new term 'both-gamete donation' was defined for the procedure that is practised here instead of 'embryo donation'. In conclusion we can say: (i) Iranian law means only embryo donation and covers only surplus embryos from other infertile couples and not both-gamete donation; (ii) as gamete donation is practised in Iran upon decrees of clergy leaders, we have no law or legislation against both-gamete donation; (iii) there are many ethical, legal and religious questions about both-gamete donation to be answered; (iv) ethical and religious questions are fewer concerning embryo donation compared with both-gamete donation; and (v) embryo sharing is a good way for donation of fresh embryos.

  8. 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.

  9. [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.

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

    PubMed

    Hadjivasiliou, Zena; Iwasa, Yoh; Pomiankowski, Andrew

    2015-08-06

    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.

  11. Production of Viable Gametes without Meiosis in Maize Deficient for an ARGONAUTE Protein[W

    PubMed Central

    Singh, Manjit; Goel, Shalendra; Meeley, Robert B.; Dantec, Christelle; Parrinello, Hugues; Michaud, Caroline; Leblanc, Olivier; Grimanelli, Daniel

    2011-01-01

    Apomixis is a form of asexual reproduction through seeds in angiosperms. Apomictic plants bypass meiosis and fertilization, developing offspring that are genetically identical to their mother. In a genetic screen for maize (Zea mays) mutants mimicking aspects of apomixis, we identified a dominant mutation resulting in the formation of functional unreduced gametes. The mutant shows defects in chromatin condensation during meiosis and subsequent failure to segregate chromosomes. The mutated locus codes for AGO104, a member of the ARGONAUTE family of proteins. AGO104 accumulates specifically in somatic cells surrounding the female meiocyte, suggesting a mobile signal rather than cell-autonomous control. AGO104 is necessary for non-CG methylation of centromeric and knob-repeat DNA. Digital gene expression tag profiling experiments using high-throughput sequencing show that AGO104 influences the transcription of many targets in the ovaries, with a strong effect on centromeric repeats. AGO104 is related to Arabidopsis thaliana AGO9, but while AGO9 acts to repress germ cell fate in somatic tissues, AGO104 acts to repress somatic fate in germ cells. Our findings show that female germ cell development in maize is dependent upon conserved small RNA pathways acting non-cell-autonomously in the ovule. Interfering with this repression leads to apomixis-like phenotypes in maize. PMID:21325139

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. A Wolbachia-Sensitive Communication between Male and Female Pupae Controls Gamete Compatibility in Drosophila.

    PubMed

    Pontier, Stéphanie M; Schweisguth, François

    2015-09-21

    Gamete compatibility is fundamental to sexual reproduction. Wolbachia are maternally inherited endosymbiotic bacteria that manipulate gamete compatibility in many arthropod species. In Drosophila, the fertilization of uninfected eggs by sperm from Wolbachia-infected males often results in early developmental arrest. This gamete incompatibility is called cytoplasmic incompatibility (CI). CI is highest in young males, suggesting that Wolbachia affect sperm properties during male development. Here, we show that Wolbachia modulate testis development. Unexpectedly, this effect was associated with Wolbachia infection in females, not males. This raised the possibility that females influenced testis development by communicating with males prior to adulthood. Using a combinatorial rearing protocol, we provide evidence for such a female-to-male communication during metamorphosis. This communication involves the perception of female pheromones by male olfactory receptors. We found that this communication determines the compatibility range of sperm. Wolbachia interfere with this female-to-male communication through changes in female pheromone production. Strikingly, restoring this communication partially suppressed CI in Wolbachia-infected males. We further identified a reciprocal male-to-female communication at metamorphosis that restricts the compatibility range of female gametes. Wolbachia also perturb this communication by feminizing male pheromone production. Thus, Wolbachia broaden the compatibility range of eggs, promoting thereby the reproductive success of Wolbachia-infected females. We conclude that pheromone communication between pupae regulates gamete compatibility and is sensitive to Wolbachia in Drosophila.

  18. Sex differences in parental care: Gametic investment, sexual selection, and social environment.

    PubMed

    Liker, András; Freckleton, Robert P; Remeš, Vladimir; Székely, Tamás

    2015-11-01

    Male and female parents often provide different type and amount of care to their offspring. Three major drivers have been proposed to explain parental sex roles: (1) differential gametic investment by males and females that precipitates into sex difference in care, (2) different intensity of sexual selection acting on males and females, and (3) biased social environment that facilitates the more common sex to provide more care. Here, we provide the most comprehensive assessment of these hypotheses using detailed parental care data from 792 bird species covering 126 families. We found no evidence for the gametic investment hypothesis: neither gamete sizes nor gamete production by males relative to females was related to sex difference in parental care. However, sexual selection correlated with parental sex roles, because the male share in care relative to female decreased with both extra-pair paternity and frequency of male polygamy. Parental sex roles were also related to social environment, because male parental care increased with male-biased adult sex ratios (ASRs). Taken together, our results are consistent with recent theories suggesting that gametic investment is not tied to parental sex roles, and highlight the importance of both sexual selection and ASR in influencing parental sex roles.

  19. Monoclonal antibodies directed against the sexual binding site of Chlamydomonas eugametos gametes

    PubMed Central

    1988-01-01

    Monoclonal antibodies were raised against the mt- sexual agglutinin of Chlamydomonas eugametos gametes. Those that blocked the agglutination site were selected. They were divided into two classes dependent upon whether they gave a weak (class A) or clear positive (class B) reaction with mt- flagellar membranes in an ELISA and an indirect immunofluorescence test using glutaraldehyde-fixed mt- gametes. Class A antibodies were shown to be specific for the agglutinin in an extract of mt- gametes, based on results from immunoblotting, immunoprecipitation, affinity chromatography, and the absence of a reaction with nonagglutinable cells. Surprisingly, class A mAbs also recognized two mt+ glycoproteins, one of which is the mt+ agglutinin. Class B antibodies were shown to bind to several glycoproteins in both mt- and mt+ gametes, including the mt- agglutinin. Fab fragments from class A mAbs blocked the sexual agglutination process, but those from class B did not, even though the parent antibody did. We conclude that the class A epitope lies in or close to the agglutination site of the mt- agglutinin, whereas the class B epitope lies elsewhere on the molecule. We also conclude that the mt- agglutinin is the only component on the mt- flagellar surface directly involved in agglutination. Class A mAbs were found to elicit several reactions displayed by the mt+ agglutinin. They bound to the mt- agglutinin on gamete flagella and induced most of the reactions typical of sexual agglutination, with the exception of flagellar tip activation. None of these reactions was induced by Fab fragments. High concentrations of class A mAbs completely repressed the sexual competence of live mt- gametes, but low concentrations stimulated cell fusion. PMID:3292540

  20. 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.

  1. 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

  2. The Ancient Gamete Fusogen HAP2 Is a Eukaryotic Class II Fusion Protein.

    PubMed

    Fédry, Juliette; Liu, Yanjie; Péhau-Arnaudet, Gérard; Pei, Jimin; Li, Wenhao; Tortorici, M Alejandra; Traincard, François; Meola, Annalisa; Bricogne, Gérard; Grishin, Nick V; Snell, William J; Rey, Félix A; Krey, Thomas

    2017-02-23

    Sexual reproduction is almost universal in eukaryotic life and involves the fusion of male and female haploid gametes into a diploid cell. The sperm-restricted single-pass transmembrane protein HAP2-GCS1 has been postulated to function in membrane merger. Its presence in the major eukaryotic taxa-animals, plants, and protists (including important human pathogens like Plasmodium)-suggests that many eukaryotic organisms share a common gamete fusion mechanism. Here, we report combined bioinformatic, biochemical, mutational, and X-ray crystallographic studies on the unicellular alga Chlamydomonas reinhardtii HAP2 that reveal homology to class II viral membrane fusion proteins. We further show that targeting the segment corresponding to the fusion loop by mutagenesis or by antibodies blocks gamete fusion. These results demonstrate that HAP2 is the gamete fusogen and suggest a mechanism of action akin to viral fusion, indicating a way to block Plasmodium transmission and highlighting the impact of virus-cell genetic exchanges on the evolution of eukaryotic life.

  3. Artificial gametes: perspectives of geneticists, ethicists and representatives of potential users.

    PubMed

    Cutas, Daniela; Dondorp, Wybo; Swierstra, Tsjalling; Repping, Sjoerd; de Wert, Guido

    2014-08-01

    Several threads of research towards developing artificial gametes are ongoing in a number of research labs worldwide. The development of a technology that could generate gametes in vitro has significant potential for human reproduction, and raises a lot of interest, as evidenced by the frequent and extensive media coverage of research in this area. We have asked researchers involved in work with artificial gametes, ethicists, and representatives of potential user groups, how they envisioned the use of artificial gametes in human reproduction. In the course of three focus groups, the participants commented on the various aspects involved. The two recurring themes were the strength of the claim of becoming a parent genetically, and the importance of responsible communication of science. The participants concurred that (a) the desire or need to have genetic offspring of one's own does not warrant the investment of research resources into these technologies, and that (b) given the minefield in terms of moral controversy and sensitivity that characterises the issues involved, how information is communicated and handled is of great importance.

  4. Selection of cryoprotectants based on their toxic effects on oyster gametes and embryos.

    PubMed

    Nascimento, Iracema A; Leite, Maria Bernadete N L; Sampaio de Araújo, Milena Maria; Sansone, Giovanni; Pereira, Solange A; do Espírito Santo, E Maristela

    2005-08-01

    Cryopreservation is a valuable tool for aquaculture by providing continuous seed production, regardless of the spawning seasons. This study aimed to select the least toxic among the cryoprotectants dimethyl sulfoxide (Me2SO), propylene glycol (PG), and methanol (MET) based on their toxicological effects on Crassostrea rhizophorae gametes and trochophores. They were exposed for 10, 20, and 30 min to a range of concentrations of those cryoprotectants. The endpoint was EC15-24 h (effective concentration which causes abnormalities in 15% of the population exposed to the cryoprotectants for 24 h), recently determined as the chronic value (the concentration at which chronic effects are first observed) for C. rhizophorae embryonic phases. There were no significant differences (p>0.05) among the exposure times in Me2SO toxic effects to either gametes or trochophores. For MET, the increase in exposure time resulted in higher toxicity for gametes, but not for trochophores, while for PG there was a significant (p>0.05) increase in toxicity with the increase of exposure for trochophores and spermatozoa, but not for oocytes. For gametes, MET was the most toxic among the cryoprotectants, while PG was the most toxic for trochophores.

  5. 9 CFR 93.903 - Import permits for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., fertilized eggs, and gametes. 93.903 Section 93.903 Animals and Animal Products ANIMAL AND PLANT HEALTH... POULTRY PRODUCTS; REQUIREMENTS FOR MEANS OF CONVEYANCE AND SHIPPING CONTAINERS Aquatic Animal Species... species to the Animal and Plant Health Inspection Service, Veterinary Services, National Center for...

  6. 9 CFR 93.904 - Health certificate for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Health certificate for live fish, fertilized eggs, and gametes. 93.904 Section 93.904 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EXPORTATION AND IMPORTATION OF ANIMALS (INCLUDING POULTRY)...

  7. 9 CFR 93.904 - Health certificate for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Health certificate for live fish, fertilized eggs, and gametes. 93.904 Section 93.904 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EXPORTATION AND IMPORTATION OF ANIMALS (INCLUDING POULTRY)...

  8. 9 CFR 93.904 - Health certificate for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Health certificate for live fish, fertilized eggs, and gametes. 93.904 Section 93.904 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EXPORTATION AND IMPORTATION OF ANIMALS (INCLUDING POULTRY)...

  9. 9 CFR 93.904 - Health certificate for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Health certificate for live fish, fertilized eggs, and gametes. 93.904 Section 93.904 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EXPORTATION AND IMPORTATION OF ANIMALS (INCLUDING POULTRY)...

  10. 9 CFR 93.904 - Health certificate for live fish, fertilized eggs, and gametes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Health certificate for live fish, fertilized eggs, and gametes. 93.904 Section 93.904 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EXPORTATION AND IMPORTATION OF ANIMALS (INCLUDING POULTRY)...

  11. 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.

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

    PubMed Central

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

    2013-01-01

    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. PMID:23570690

  14. 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.

  15. Ethanol stimulates phospholipid turnover and inositol 1,4,5-trisphosphate production in Chlamydomonas eugametos gametes.

    PubMed

    Musgrave, A; Kuin, H; Jongen, M; de Wildt, P; Schuring, F; Klerk, H; van den Ende, H

    1992-02-01

    Alcohols induce mating-structure activation in Chlamydomonas eugametos gametes. From the effect of ethanol on the (32)P-labelling of polyphosphoinositides, we conclude that the synthesis of these lipids is stimulated. Biologically inactive concentrations of ethanol (<6%) had no effect on synthesis, but 6-8% ethanol stimulated synthesis for upto 60 min. The (32)P incorporated into polyphosphoinositides and phosphatidic acid during ethanol treatment was readily chased out when 1 mM unlabelled Na3PO4 was added. Using a binding assay for inositol 1,4,5-trisphosphate, we show that the production of this phospholipid constituent is dramatically increased after ethanol treatment. This effect, coupled to a rise in intracellular calcium concentration, could explain gamete activation. The significance of these results in explaining other ethanol-induced phenomena in algae is discussed.

  16. 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

  17. Gametophytic Pollen Tube Guidance: Attractant Peptides, Gametic Controls, and Receptors1[OPEN

    PubMed Central

    2017-01-01

    Pollen tube guidance in flowering plants is a unique and critical process for successful sexual reproduction. The pollen tube that grows from pollen, which is the male gametophyte, precisely navigates to the embryo sac, which is the female gametophyte, within the pistil. Recent advances have clarified the molecular framework of gametophytic pollen tube guidance. Multiple species-specific attractant peptides are secreted from synergid cells, the proper development and function of which are regulated by female gametes. Multiple receptor-like kinases on the pollen tube tip are involved in sensing species-specific attractant peptides. In this Update article, recent progress in our understanding of the mechanism of gametophytic pollen tube guidance is reviewed, including attraction by synergid cells, control of pollen tube guidance by female gametes, and directional growth of the pollen tube by directional cue sensing. Future directions in the study of pollen tube guidance also are discussed. PMID:27920159

  18. In vitro fertilization with rice gametes: production of zygotes and zygote and embryo culture.

    PubMed

    Okamoto, Takashi

    2011-01-01

    In vitro fertilization (IVF) systems using isolated male and female gametes have been utilized to dissect fertilization-induced events in angiosperms, such as egg activation, zygote development, and early embryogenesis, since the female gametophytes of plants are deeply embedded within ovaries. A rice IVF system was established to take advantage of the abundant resources stemming from rice research for investigations into the mechanisms of fertilization and early embryogenesis. Fusion of gametes can be performed using electrofusion and the fusion product, a zygote, forms a cell wall and an additional nucleolus. The zygote divides into an asymmetric two-celled embryo and develops into an early globular embryo, as in planta. The embryo further develops into irregularly shaped cell masses and fertile plants can be regenerated from the cell masses. This rice IVF system is a powerful tool for studying the molecular mechanisms involved in the early embryogenesis of angiosperms and for making new cultivars.

  19. 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.

  20. 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.

  1. 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

    ... importation of live fish, fertilized eggs, and gametes. (a) The following ports are designated as ports of...: (1) Air and ocean ports. Los Angeles and San Francisco, CA; Miami and Tampa, FL; Atlanta,...

  2. 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

    ... importation of live fish, fertilized eggs, and gametes. (a) The following ports are designated as ports of...: (1) Air and ocean ports. Los Angeles and San Francisco, CA; Miami and Tampa, FL; Atlanta,...

  3. 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

  4. 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

  5. Transcript isoforms of promyelocytic leukemia in mouse male and female gametes.

    PubMed

    Ebrahimian, Mahboobeh; Mojtahedzadeh, Mahsa; Bazett-Jones, David; Dehghani, Hesam

    2010-01-01

    Promyelocytic leukemia (PML) nuclear bodies and proteins have been implicated in many functions of the nucleus. It is not known whether the PML gene is transcribed and expressed as PML nuclear bodies in gamete cells or in the early mammalian embryo. In this study using reverse transcription-polymerase chain reaction and immunocytochemistry we show the presence of PML transcripts and identify their variants in the mature mouse gametes. Mature sperm contains isoform II; however, oocyte contains transcript isoforms I, II, and possibly other unknown isoforms of PML. This indicates that the mature gametes may carry the transcripts to the newly created embryo. We also show that sperm and oocyte cells do not contain PML nuclear bodies. We find that the first appearance of PML nuclear bodies is in the 2-cell-stage mouse embryo. Appearance of PML nuclear bodies in the 2-cell-stage embryo may correspond to the major transcriptional activity of the embryonic genome. In summary, this report emphasizes the necessity to perform further experiments to investigate the presence and function of PML transcripts and nuclear bodies in earlier stages of germ cell and also later stages of the preimplantation development.

  6. 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.

  7. 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.

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

    PubMed

    Oliver, Mathew; Evans, Jonathan P

    2014-06-07

    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.

  9. 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.

  10. 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.

  11. Beneath the rhetoric: the role of rights in the practice of non-anonymous gamete donation.

    PubMed

    Frith, L

    2001-10-01

    The use of rights based arguments to justify claims that donor offspring should have access to information identifying their gamete donor has become increasingly widespread. In this paper, I do not intend to revisit the debate about the validity of such rights. Rather, the purpose is to examine the way such alleged rights have been implemented by those legislatures that have allowed access to identifying information. I will argue that serious inconsistencies exist between the claim that donor offspring have a right to know the identity of their gamete donor and the way such a right is currently met in practice. I hope to show that in systems where non-anonymous donation is practised, an understanding of the proclaimed right of donor offspring to know their genetic identity is one composed of two different rights--the right to know the circumstances of their conception and the right to information identifying the gamete donor--can provide important insights into this important area of public policy.

  12. Gamete cytogenetic study in couples with implantation failure: aneuploidy rate is increased in both couple members

    PubMed Central

    Hammoud, I.; Molina-Gomes, D.; Wainer, R.; Bergere, M.; Albert, M.; Bailly, M.; de Mazancourt, P.; Selva, J.

    2008-01-01

    Purpose Implantation failure is known to be associated with an increased risk of aneuploidy in embryos, a situation leading to a pre-implantation genetic screening, not allowed in different countries like France. Our aim was to evaluate the gamete aneuploidy incidence in this context, using first polar body and spermatozoa aneuploidy screening. Methods Three groups were considered: 11 couples with pregnancy obtained after IVF for female infertility (group 1); 20 couples with pregnancy obtained after IVF for male infertility (group 2); and 35 couples with implantation failure (group 3). In group 3, 28 couples treated by ICSI volunteered for first polar body analysis (PB1). Results Spermatozoa aneuploidy rate was increased in groups 2 (1.6%) and 3 (2.1%) in comparison to group 1 (0.6%). PB1 aneuploidy rate was 35.4% in group 3. Finally, eight couples (32%) had no particular chromosomal risk in gametes, 15/25 (60%) presented an increased spermatic (>2%) or oocyte (>1/3) aneuploidy rate, and 2/25 (8%) had both. Conclusion Those results confirm that implantation failure has a heterogeneous origin, that gamete chromosome abnormality rate is one of the major contributing factors, and that 1st Polar body and spermatozoa aneuploidy screening or pre-implantation genetics screening may be indicated for these couples. PMID:18972203

  13. 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.

  14. Gamete fusion is required to block multiple pollen tubes from entering an Arabidopsis ovule.

    PubMed

    Beale, Kristin M; Leydon, Alexander R; Johnson, Mark A

    2012-06-19

    In double fertilization, a reproductive system unique to flowering plants, two immotile sperm are delivered to an ovule by a pollen tube. One sperm fuses with the egg to generate a zygote, the other with the central cell to produce endosperm. A mechanism preventing multiple pollen tubes from entering an ovule would ensure that only two sperm are delivered to female gametes. We use live-cell imaging and a novel mixed-pollination assay that can detect multiple pollen tubes and multiple sets of sperm within a single ovule to show that Arabidopsis efficiently prevents multiple pollen tubes from entering an ovule. However, when gamete-fusion defective hap2(gcs1) or duo1 sperm are delivered to ovules, as many as three additional pollen tubes are attracted. When gamete fusion fails, one of two pollen tube-attracting synergid cells persists, enabling the ovule to attract more pollen tubes for successful fertilization. This mechanism prevents the delivery of more than one pair of sperm to an ovule, provides a means of salvaging fertilization in ovules that have received defective sperm, and ensures maximum reproductive success by distributing pollen tubes to all ovules.

  15. 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

  16. 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.

  17. Significant change of alignment effect by dimer formation in the dissociative energy transfer reaction of Ar(3P2)+(N2O)n and (H2O)n

    NASA Astrophysics Data System (ADS)

    Watanabe, D.; Ohoyama, H.; Matsumura, T.; Kasai, T.

    2006-12-01

    An alignment effect in the dissociative energy transfer reaction of Ar(P23)+(X2O)n(X=N,H) was directly measured using an oriented Ar(P23,MJ=2) beam. The chemiluminescence intensity of N2(B,Πg3) for (N2O)n and OH(A,Σ+2) for (H2O)n was measured as a function of the magnetic orientation field direction in the collision frame. The relative reaction cross section for each magnetic substate in the collision frame, σMJ', was determined. In both the reaction systems, it is observed that the dimer formation significantly enhances the alignment effect and decreases the reactivity, especially for σ∣1∣ and σ∣2∣. A significant contribution of rank 4 moment is recognized in the dimer reaction.

  18. Structure-Function Studies Link Class II Viral Fusogens with the Ancestral Gamete Fusion Protein HAP2.

    PubMed

    Pinello, Jennifer Fricke; Lai, Alex L; Millet, Jean K; Cassidy-Hanley, Donna; Freed, Jack H; Clark, Theodore G

    2017-03-06

    The conserved transmembrane protein, HAP2/GCS1, has been linked to fertility in a wide range of taxa and is hypothesized to be an ancient gamete fusogen. Using template-based structural homology modeling, we now show that the ectodomain of HAP2 orthologs from Tetrahymena thermophila and other species adopt a protein fold remarkably similar to the dengue virus E glycoprotein and related class II viral fusogens. To test the functional significance of this predicted structure, we developed a flow-cytometry-based assay that measures cytosolic exchange across the conjugation junction to rapidly probe the effects of HAP2 mutations in the Tetrahymena system. Using this assay, alterations to a region in and around a predicted "fusion loop" in T. thermophila HAP2 were found to abrogate membrane pore formation in mating cells. Consistent with this, a synthetic peptide corresponding to the HAP2 fusion loop was found to interact directly with model membranes in a variety of biophysical assays. These results raise interesting questions regarding the evolutionary relationships of class II membrane fusogens and harken back to a long-held argument that eukaryotic sex arose as the byproduct of selection for the horizontal transfer of a "selfish" genetic element from cell to cell via membrane fusion.

  19. Diploid clone produces unreduced diploid gametes but tetraploid clone generates reduced diploid gametes in the Misgurnus loach.

    PubMed

    Morishima, Kagayaki; Yoshikawa, Hiroyuki; Arai, Katsutoshi

    2012-02-01

    Most individuals of the loach Misgurnus anguillicaudatus reproduce bisexually, but cryptic clonal lineages reproduce by natural gynogenesis of unreduced diploid eggs that are genetically identical to maternal somatic cells. Triploid progeny often occur by the accidental incorporation of a sperm nucleus into diploid eggs. Sex reversal from a genetic female to a physiological male is easily induced in this species by androgen treatment and through environmental influences. Here, we produced clonal tetraploid individuals by two methods: 1) fertilization of diploid eggs from a clonal diploid female with diploid sperm of a hormonally sex-reversed clonal diploid male and 2) artificial inhibition of the release of the second polar body in eggs of clonal diploid females just after initiation of gynogenetic development. There is no genetic difference between the clonal diploid and tetraploid individuals except for the number of chromosome sets or genomes. Clonal tetraploid males never produced unreduced tetraploid sperm, only diploid sperm that were genetically identical to those of a clonal diploid. Likewise, clonal tetraploid females did not form unreduced tetraploid eggs, just diploid eggs. However, the eggs' genotypes were identical to those of the original clone, and almost all the eggs initiated natural gynogenesis. Thus, gametogenesis of the clonal tetraploid loach is controlled by the presence of two chromosome sets to pair, thereby preserving the normal meiotic process, i.e., the formation of bivalents and subsequently two successive divisions.

  20. 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

  1. Characterization of gametes in two phyllostomid bat species: Artibeus jamaicensis and Sturnira lilium.

    PubMed

    Álvarez-Guerrero, Alma; Medrano, Alfredo; Moreno-Mendoza, Norma

    2014-03-01

    Morphology of gametes is used to understand the physiological processes in reproduction among domestic and wild animals. These gametes are used in assisted reproductive technology (ART) and conservation programs. In the case of Artibeus jamaicensis and Sturnira lilium, few studies have been conducted related to these issues. The aim of this study was to describe the structure of spermatozoa, semen characteristics and also the morphology and quality of cumulus oocyte complexes (COC) of A. jamaicensis and S. lilium. Semen characteristics were: A. jamaicensis had a sperm concentration of 4.26×10(6)sperm/ml, progressive motility of 34.55%; viability of 73.23%; head, tail and mid-piece abnormalities of 12.50%. Head length was 6.26μm, mid-piece 18.61μm and tail 70.92μm. S. lilium, had a sperm concentration of 5.15×10(6)sperm/ml, progressive motility of 60.00%, viability of 83.82%; abnormalities in head, tail and mid-piece of 13.77%. Head length was 7.01μm, mid-piece 20.33μm and tail 70.50μm. On average 12.8 of right ovarian oocytes and 9.9 of left ovarian oocytes of A. jamaicensis were recovered. For S. lilium on average 10.7 oocytes from the right ovary and 10.9 oocytes from the left ovary were recovered, ranging in quality from excellent to poor. Sperm morphology and quality of COC were similar to those for other domestic and wild animals. Bat gametes can be used for the study of reproductive biology, in conservation programs and assisted reproductive technology (ART) among domestic and wild animals.

  2. Cardiac Arrest during Gamete Release in Chum Salmon Regulated by the Parasympathetic Nerve System

    PubMed Central

    Makiguchi, Yuya; Nagata, Shinya; Kojima, Takahito; Ichimura, Masaki; Konno, Yoshifumi; Murata, Hideki; Ueda, Hiroshi

    2009-01-01

    Cardiac arrest caused by startling stimuli, such as visual and vibration stimuli, has been reported in some animals and could be considered as an extraordinary case of bradycardia and defined as reversible missed heart beats. Variability of the heart rate is established as a balance between an autonomic system, namely cholinergic vagus inhibition, and excitatory adrenergic stimulation of neural and hormonal action in teleost. However, the cardiac arrest and its regulating nervous mechanism remain poorly understood. We show, by using electrocardiogram (ECG) data loggers, that cardiac arrest occurs in chum salmon (Oncorhynchus keta) at the moment of gamete release for 7.39±1.61 s in females and for 5.20±0.97 s in males. The increase in heart rate during spawning behavior relative to the background rate during the resting period suggests that cardiac arrest is a characteristic physiological phenomenon of the extraordinarily high heart rate during spawning behavior. The ECG morphological analysis showed a peaked and tall T-wave adjacent to the cardiac arrest, indicating an increase in potassium permeability in cardiac muscle cells, which would function to retard the cardiac action potential. Pharmacological studies showed that the cardiac arrest was abolished by injection of atropine, a muscarinic receptor antagonist, revealing that the cardiac arrest is a reflex response of the parasympathetic nerve system, although injection of sotalol, a β-adrenergic antagonist, did not affect the cardiac arrest. We conclude that cardiac arrest during gamete release in spawning release in spawning chum salmon is a physiological reflex response controlled by the parasympathetic nervous system. This cardiac arrest represents a response to the gaping behavior that occurs at the moment of gamete release. PMID:19543389

  3. Cardiac arrest during gamete release in chum salmon regulated by the parasympathetic nerve system.

    PubMed

    Makiguchi, Yuya; Nagata, Shinya; Kojima, Takahito; Ichimura, Masaki; Konno, Yoshifumi; Murata, Hideki; Ueda, Hiroshi

    2009-06-19

    Cardiac arrest caused by startling stimuli, such as visual and vibration stimuli, has been reported in some animals and could be considered as an extraordinary case of bradycardia and defined as reversible missed heart beats. Variability of the heart rate is established as a balance between an autonomic system, namely cholinergic vagus inhibition, and excitatory adrenergic stimulation of neural and hormonal action in teleost. However, the cardiac arrest and its regulating nervous mechanism remain poorly understood. We show, by using electrocardiogram (ECG) data loggers, that cardiac arrest occurs in chum salmon (Oncorhynchus keta) at the moment of gamete release for 7.39+/-1.61 s in females and for 5.20+/-0.97 s in males. The increase in heart rate during spawning behavior relative to the background rate during the resting period suggests that cardiac arrest is a characteristic physiological phenomenon of the extraordinarily high heart rate during spawning behavior. The ECG morphological analysis showed a peaked and tall T-wave adjacent to the cardiac arrest, indicating an increase in potassium permeability in cardiac muscle cells, which would function to retard the cardiac action potential. Pharmacological studies showed that the cardiac arrest was abolished by injection of atropine, a muscarinic receptor antagonist, revealing that the cardiac arrest is a reflex response of the parasympathetic nerve system, although injection of sotalol, a beta-adrenergic antagonist, did not affect the cardiac arrest. We conclude that cardiac arrest during gamete release in spawning release in spawning chum salmon is a physiological reflex response controlled by the parasympathetic nervous system. This cardiac arrest represents a response to the gaping behavior that occurs at the moment of gamete release.

  4. Cyclic AMP functions as a primary sexual signal in gametes of Chlamydomonas reinhardtii.

    PubMed

    Pasquale, S M; Goodenough, U W

    1987-11-01

    When Chlamydomonas reinhardtii gametes of opposite mating type are mixed together, they adhere by a flagella-mediated agglutination that triggers three rapid mating responses: flagellar tip activation, cell wall loss, and mating structure activation accompanied by actin polymerization. Here we show that a transient 10-fold elevation of intracellular cAMP levels is also triggered by sexual agglutination. We further show that gametes of a single mating type can be induced to undergo all three mating responses when presented with exogenous dibutyryl-cAMP (db-cAMP). These events are also induced by cyclic nucleotide phosphodiesterase inhibitors, which elevate endogenous cAMP levels and act synergistically with db-cAMP. Non-agglutinating mutants of opposite mating type will fuse efficiently in the presence of db-cAMP. No activation of mating events is induced by calcium plus ionophores, 8-bromo-cGMP, dibutyryl-cGMP, nigericin at alkaline pH, phorbol esters, or forskolin. H-8, an inhibitor of cyclic nucleotide-dependent protein kinase, inhibits mating events in agglutinating cells and antagonizes the effects of cAMP on non-agglutinating cells. Adenylate cyclase activity was detected in both the gamete cell body and flagella, with the highest specific activity displayed in flagellar membrane fractions. The flagellar membrane adenylate cyclase is preferentially stimulated by Mn++, unresponsive to NaF, GTP, GTP gamma S, AlF4-, and forskolin, and is inhibited by trifluoperazine. Cyclic nucleotide phosphodiesterase activity is also present in flagella. Our observations indicate that cAMP is a sufficient initial signal for all of the known mating reaction events in C. reinhardtii, and suggest that the flagellar cyclase and/or phosphodiesterase may be important loci of control for the agglutination-stimulated production of this signal.

  5. ESHRE Task Force on Ethics and Law 21: genetic screening of gamete donors: ethical issues.

    PubMed

    Dondorp, W; De Wert, G; Pennings, G; Shenfield, F; Devroey, P; Tarlatzis, B; Barri, P; Diedrich, K; Eichenlaub-Ritter, U; Tüttelmann, F; Provoost, V

    2014-07-01

    This Task Force document explores the ethical issues involved in the debate about the scope of genetic screening of gamete donors. Calls for expanded donor screening arise against the background of both occasional findings of serious but rare genetic conditions in donors or donor offspring that were not detected through present screening procedures and the advent of new genomic technologies promising affordable testing of donors for a wide range of conditions. Ethical principles require that all stakeholders' interests are taken into account, including those of candidate donors. The message of the profession should be that avoiding all risks is impossible and that testing should remain proportional.

  6. Progress, challenges and perspectives on fish gamete cryopreservation: A mini-review.

    PubMed

    Asturiano, Juan F; Cabrita, Elsa; Horváth, Ákos

    2016-06-15

    Protocols for the cryopreservation of fish gametes have been developed for many different fish species, in special, freshwater salmonids and cyprinids. Methods for sperm freezing have progressed during the last decades due to the increasing number of potential applications: aquaculture (genetic improvement programs, broodstock management, helping with species having reproductive problems), biotechnology studies using model fish species (preservation of transgenic or mutant lines), cryobanking of genetic resources from endangered species, etc. This mini-review tries to give an overview of the present situation of this area of research, identifying the main challenges and perspectives, redirecting the reader to more in-depth reviews and papers.

  7. Attitudes toward making babies … with a deceased partner's cryopreserved gametes.

    PubMed

    Hans, Jason D; Dooley, Brigitte

    2014-01-01

    A multiple segment factorial vignette was used with a probability sample of 857 U.S. households to assess the effects of contextual variables on attitudes toward posthumous reproduction using the cryopreserved gametes of a deceased partner. Attitudes were affected in predictable directions by marital status, gender of the deceased individual, disposition of the deceased's parents, and the deceased's wishes. In addition, respondents who identified more closely with their chosen religion tended to perceive posthumous conception as less appropriate and those who had never had children attributed a greater degree of obligation to assist on the part of medical professionals.

  8. Novel gamete receptors that facilitate sperm adhesion to the egg coat.

    PubMed

    Ensslin, Michael A; Lyng, Robert; Raymond, Adam; Copland, Susannah; Shur, Barry D

    2007-01-01

    Mammalian fertilization is initiated by species-specific binding of the sperm to the zona pellucida, or egg coat. Previous studies suggested that sperm adhesion to the egg coat is facilitated, at least in part, through the binding of sperm surface beta1 ,4-galactosyltransferase I (GaIT) to glycoside chains on the egg coat glycoprotein, ZP3. Binding of multiple ZP3 oligosaccharides induces aggregation of GaIT within the sperm membrane, triggering, directly or indirectly, a pertussis toxin sensitive G-protein cascade leading to induction of the acrosome reaction. Consistent with this, spermatozoa bearing targeted deletions in GaIT are unable to bind ZP3 or undergo ZP3-dependent acrosomal exocytosis; however, unexpectedly, GaIT-null sperm are still able to bind to the egg coat. This indicates that sperm-egg binding requires at least two independent binding mechanisms; a GaIT-ZP3-independent event that mediates initial adhesion, followed by a GaIT-ZP3 interaction that facilitates acrosomal exocytosis. Our recent efforts have focused on the identification and characterization of these novel gamete receptors. One recently identified sperm protein that is required for sperm adhesion to the egg coat is SED1. SED1 is a bimotif protein composed of two Notch-like EGF repeats and two discoidin/complement F5/8 domains. SED1 is secreted by the epididymal epithelium and coats spermatozoa as they progress through the epididymis. Spermatozoa null for SED1 fail to bind the egg coat, illustrating its requirement for gamete adhesion. Interestingly, SED1 is also expressed by a variety of other epithelial tissues, where it appears to be required for epithelial morphogenesis and/or maintenance. A second novel gamete receptor has recently been identified on the coat of ovulated oocytes. This ZP3-independent, egg coat component is a high molecular weight, wheat germ agglutinin (WGA)-reactive glycoprotein that is derived from oviduct secretions and appears to participate in initial sperm

  9. 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.

  10. 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.

  11. Haploid and doubled haploid plants from developing male and female gametes of Gentiana triflora.

    PubMed

    Pathirana, Ranjith; Frew, Tonya; Hedderley, Duncan; Timmerman-Vaughan, Gail; Morgan, Ed

    2011-06-01

    Protocols were developed for the generation of haploid or doubled haploid plants from developing microspores and ovules of Gentiana triflora. Plant regeneration was achieved using flower buds harvested at the mid to late uninucleate stages of microspore development and then treated at 4°C for 48 h prior to culture. Anthers and ovaries were cultured on modified Nitsch and Nitsch medium supplemented with a combination of naphthoxyacetic acid and benzylaminopurine. The explants either regenerated new plantlets directly or produced callus that regenerated into plantlets upon transfer to basal media supplemented with benzylaminopurine. Among seven genotypes of different ploidy levels used, 0-32.6% of cultured ovary pieces and 0-18.4% of cultured anthers regenerated plants, with all the genotypes responding either through ovary or anther culture. Flow cytometry confirmed that 98% of regenerated plants were either diploid or haploid. Diploid regenerants were shown to be gamete-derived by observing parental band loss using RAPD markers. Haploid plants were propagated on a proliferation medium and then treated with oryzalin for 4 weeks before transfer back to proliferation medium. Most of the resulting plants were diploids. Over 150 independently derived diploidised haploid plants have been deflasked. The protocol has been successfully used to regenerate plants from developing gametes of seven different diploid, triploid and tetraploid G. triflora genotypes.

  12. Canonical and cellular pathways timing gamete release in Acropora digitifera, Okinawa, Japan.

    PubMed

    Rosenberg, Y; Doniger, T; Harii, S; Sinniger, F; Levy, O

    2017-02-18

    Natural light cycles are important for synchronizing behavioural and physiological rhythms over varying time periods in both plants and animals. An endogenous clock, regulated by positive and negative elements, interacting in feedback loops controls these rhythms. Many corals exhibit diel cycles of polyp expansion and contraction entrained by solar light patterns and monthly cycles of spawning or planulation that correspond to nocturnal lunar light cycles. However, despite considerable interest in studies of coral reproduction, there is currently not enough molecular information about the cellular pathways involved with synchronizing spawning/planulation in broadcast spawners and brooders. To determine whether the endogenous clock is implicated in the regulation of reproductive behaviour in corals, we characterized the transcriptome of Acropora digitifera colonies at twelve time points over a 2-month period of full and new moons, starting with the day of spawning in June 2014. We identified 608 transcripts with differential expression only on the spawning night during the coral setting phase and gamete release. Our data revealed an upregulation of light-sensing molecules and rhodopsin-like receptors that initiate signalling cascades, including the glutamate, SMAD signalling and WNT signalling pathways, neuroactive ligand-receptor interactions and calcium signalling. These are all involved in cell cycling, cell movement, tissue polarity, focal adhesion and cytoskeleton reorganization and together lead to gamete release. These findings can improve the understanding of many time-based cycles and extend our knowledge of the interplay between exogenous signals and the endogenous clock in cnidarians.

  13. 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

  14. 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.

  15. Calmodulin-binding proteins are developmentally regulated in gametes and embryos of fucoid algae

    SciTech Connect

    Brawley, S.H.; Roberts, D.M.

    1989-02-01

    Calcium-binding proteins and calmodulin-binding proteins were identified in gametes and zygotes of the marine brown algae Fucus vesiculosus, Fucus distichus, and Pelvetia fastigiata using gel (SDS-PAGE) overlay techniques. A calcium current appears to be important during cell polarization in fucoid zygotes, but there are no biochemical data on calcium-binding proteins in these algae. By using a sensitive 45Ca2+ overlay method designed to detect high-affinity calcium-binding proteins, at least 9-11 polypeptides were detected in extracts of fucoid gametes and zygotes. All samples had calcium-binding proteins with apparent molecular weights of about 17 and 30 kDa. A 17-kDa calcium-binding protein was purified by calcium-dependent hydrophobic chromatography and was identified as calmodulin by immunological and enzyme activator criteria. A 125I-calmodulin overlay assay was used to identify potential targets of calmodulin action. Sperm contained one major calmodulin-binding protein of about 45 kDa. Eggs lacked major calmodulin-binding activity. A 72-kDa calmodulin-binding protein was prominent in zygotes from 1-65 hr postfertilization. Both calmodulin-binding proteins showed calcium-dependent binding activity. Overall, the data suggest that the appearance and distribution of certain calcium-binding and calmodulin-binding proteins are under developmental regulation, and may reflect the different roles of calcium during fertilization and early embryogenesis.

  16. 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

  17. 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.

  18. 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.

  19. Procuring gametes for research and therapy: the argument for unisex altruism--a response to Donald Evans.

    PubMed

    Dickenson, D L

    1997-04-01

    There has been a troublesome anomaly in the UK between cash payment to men for sperm donation and the effective assumption that women will pay to donate eggs. Some commentators, including Donald Evans in this journal, have argued that the anomaly should be resolved by treating women on the same terms as men. But this argument ignores important difficulties about property in the body, particularly in relation to gametes. There are good reasons for thinking that the contract model and payment for gametes are both inappropriate, and that a model based on altruism should be applied to both sexes.

  20. Contemporary evolution of sea urchin gamete-recognition proteins: experimental evidence of density-dependent gamete performance predicts shifts in allele frequencies over time.

    PubMed

    Levitan, Don R

    2012-06-01

    Species whose reproductive strategies evolved at one density regime might be poorly adapted to other regimes. Field and laboratory experiments on the sea urchin Strongylocentrotus franciscanus examined the influences of the two most common sperm-bindin alleles, which differ at two amino acid sites, on fertilization success. In the field experiment, the arginine/glycine (RG) genotype performed best at low densities and the glycine/arginine (GR) genotype at high densities. In the laboratory experiment, the RG genotype had a higher affinity with available eggs, whereas the GR genotype was less likely to induce polyspermy. These sea urchins can reach 200 years of age. The RG allele dominates in larger/old sea urchins, whereas smaller/younger sea urchins have near-equal RG and GR allele frequencies. A latitudinal cline in RG and GR genotypes is consistent with longer survival of sea urchins in the north and with predominance of RG genotypes in older individuals. The largest/oldest sea urchins were likely conceived at low densities, before sea-urchin predators, such as sea otters, were overharvested and sea-urchin densities exploded off the west coast of North America. Contemporary evolution of gamete-recognition proteins might allow species to adapt to shifts in abundances and reduces the risk of reproductive failure in altered populations.

  1. 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.

  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. Theoretical microwave spectral constants for C2N, C2N/+/, and C3H

    NASA Technical Reports Server (NTRS)

    Green, S.

    1980-01-01

    Theoretical microwave spectral constants have been computed for C2N, C3H, and C2N(+). For C2N these are compared with values obtained from optical data. Calculated hyperfine constants are also presented for HNC, DNC, and HCNH(+). The possibility of observing these species in dense interstellar clouds is discussed.

  6. Superfetation occurring in connection with gamete intrafallopian transfer: a case report.

    PubMed

    Krenn, V; Marx, A; Wiedemann, R; Müller-Hermelink, H K; Kranzfelder, D

    1995-01-01

    This observation reports a case of susperfetation which occurred in connection with gamete intrafallopian transfer (GIFT). The macroscopic and histological examination of a spontaneous abortion from a 33-year-old woman (15th week of pregnancy) revealed the existence of two embryos with a monochorionic diamniotic placenta (developmental age approximately 41 days) and two fetuses and a fetal remnant with a trichorionic and triamniotic placenta (developmental age approximately 98 days). The large developmental age difference of embryos and fetuses cannot be explained by retardation, because the embryos showed adequate development with the development of their placenta. Moreover, the usual causes of intrauterine growth retardation could be excluded as could retention of the embryos since the tissues showed no autolytic changes. Consequently the large developmental age difference is explained by assuming that the embryos developed from successive ovulations. A second nidation of blastocysts had occurred after the GIFT concurrently with the clinically reported hyperstimulation syndrome.

  7. 58 RADIO-FREQUENCY IDENTIFICATION INTELI-STRAWS: GAMETES AND EMBRYO PACKAGING, STORAGE, AND INFORMATION RECOVERY.

    PubMed

    Kjelland, M E; Loper, T; Woodley, C; Swannack, T M; Stroud, T K; Romo, S

    2016-01-01

    The assisted reproduction industry involving sales and services for gametes and embryos for domestic animals of commercial value is a large market totaling millions of dollars annually. The objective of this study was to develop and test gamete and embryo packaging-Inteli-Straws (I-S) equipped with radio-frequency identification (RFID) technology. Specifically, French straws (0.25 and 0.5mL) were modified to include extreme cold-tolerant RFID microchips. Two groups of I-S were formed: Group (G)1: RFID chips that were autoclaved (n=49), and G2: RFID chips that were not autoclaved (n=47). Both groups had a control that was not exposed to liquid nitrogen (LN). Each group was exposed to LN up to 4 times: 2 slow freezes first and then 2 fast (i.e. vitrification) freezes, and I-S RFID chip survival was determined. I-S detection and readability (non-autoclaved) was also measured, placing I-S just above LN (in vapors, n=43) or just below LN (n=38). Statistical differences (α=0.05) were determined using Fisher's exact test. The results between G1 and G2 were not significantly different (P=0.108) after 4 rounds of cryopreservation (and thawing). For G1, 98% (48/49) of the I-S RFID chips remained operational, and control and treatment were not significantly different (P=1.000). For G2, 89.4% (42/47) of the autoclaved RFID chips remained operational, and control and treatment not significantly different (P=0.099). RFID chip readability results; that is, the ability to detect the I-S versus not able to detect the I-S, comparing placement just above liquid nitrogen (LN) versus the placement just below LN were not significantly different (P=0.105). Notably, detection differences varied within each group, with I-S in G1 (mean=9.5; SD=3.5cm) readable at a larger distance, 5.2cm farther than the mean of G2 (mean=4.3; SD=1.9cm). During AI or embryo transfer (ET), a technician may not clearly identify the label or colour of straw, may incorrectly record the information, or may take

  8. Female-induced remote regulation of sperm physiology may provide opportunities for gamete-level mate choice.

    PubMed

    Kekäläinen, Jukka; Evans, Jonathan P

    2017-02-01

    In sedentary externally fertilizing species, direct interactions between mating partners are limited and prefertilization communication between sexes occurs largely at the gamete level. Certain combinations of eggs and sperm often have higher fertilization success than others, which may be contingent on egg-derived chemical factors that preferentially attract sperm from compatible males. Here, we examine the mechanisms underlying such effects in the marine mussel Mytilus galloprovincialis, where differential sperm attraction has recently been shown to be associated with variation in offspring viability. Specifically, we focus on the sperm surface glycans, an individually unique layer of carbohydrates that moderate self-recognition and other cellular-level interactions. In many species egg-derived factors trigger remarkable changes in the sperm's glycan layer, physiology, and swimming behavior, and thus potentially moderate mate choice at the gamete level. Here, we show that sperm glycan modifications and the strength of acrosome reaction are both dependent on specific male-female interactions (male-female combination). We also find associations between female-induced sperm glycan changes and the Ca(2+) influx into sperm--a key regulator of fertilization processes from sperm capacitation to gamete fusion. Together, our results suggest that female-induced remote regulation of sperm physiology may constitute a novel mechanism of gamete-level mate choice.

  9. 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

  10. Recommendations for reducing the risk of viral transmission during fertility treatment with the use of autologous gametes: a committee opinion.

    PubMed

    2013-02-01

    This document provides strategies, based on scientific principles and clinical experience, to reduce the risk of viral transmission in couples seeking treatment for infertility using their own gametes. This document replaces the ASRM Practice Committee document, "Guidelines for reducing the risk of viral transmission during fertility treatment," last published in Fertil Steril 2008;90(5 Suppl):S156-62.

  11. 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.

  12. The levels of male gametic mitochondrial DNA are highly regulated in angiosperms with regard to mitochondrial inheritance.

    PubMed

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

    2010-07-01

    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.

  13. Sex-Specific Posttranslational Regulation of the Gamete Fusogen GCS1 in the Isogamous Volvocine Alga Gonium pectorale

    PubMed Central

    Kawai-Toyooka, Hiroko; Mori, Toshiyuki; Hamaji, Takashi; Suzuki, Masahiro; Olson, Bradley J. S. C.; Uemura, Tomohiro; Ueda, Takashi; Nakano, Akihiko; Toyoda, Atsushi; Fujiyama, Asao

    2014-01-01

    Male and female, generally defined based on differences in gamete size and motility, likely have multiple independent origins, appearing to have evolved from isogamous organisms in various eukaryotic lineages. Recent studies of the gamete fusogen GCS1/HAP2 indicate that this protein is deeply conserved across eukaryotes, and its exclusive and/or functional expression generally resides in males or in male homologues. However, little is known regarding the conserved or primitive molecular traits of males and females within eukaryotes. Here, using morphologically indistinguishable isogametes of the colonial volvocine Gonium pectorale, we demonstrated that GCS1 is differently regulated between the sexes. G. pectorale GCS1 molecules in one sex (homologous to male) are transported from the gamete cytoplasm to the protruded fusion site, whereas those of the other sex (females) are quickly degraded within the cytoplasm upon gamete activation. This molecular trait difference might be conserved across various eukaryotic lineages and may represent male and female prototypes originating from a common eukaryotic ancestor. PMID:24632243

  14. Comparative cryobiological traits and requirements for gametes and gonadal tissues collected from wildlife species.

    PubMed

    Comizzoli, P; Songsasen, N; Hagedorn, M; Wildt, D E

    2012-11-01

    A major challenge to retaining viability of frozen gametes and reproductive tissues is to understand and overcome species-specificities, especially because there is substantial diversity in cryobiological properties and requirements among cell types and tissues. Systematic studies can lead to successful post-thaw recovery, especially after determining: 1) membrane permeability to water and cryoprotectant, 2) cryoprotectant toxicity, 3) tolerance to osmotic changes, and 4) resistance to cooling and freezing temperatures. Although species-dependency ultimately dictates the ability of specific cells and tissues to survive freeze-thawing, there are commonalities between taxa that allow a protocol developed for one species to be useful information for another. This is the reason for performing comparative cryopreservation studies among diverse species. Our laboratory has compared cellular cryotolerance, especially in spermatozoa, in a diverse group of animals-from corals to elephants-for more than 30 yrs. Characterizing the biophysical traits of gametes and tissues is the most efficient way to develop successful storage and recovery protocols, but, such data are only available for a few laboratory, livestock, and fish species, with virtually all others (wild mammals, birds, reptiles, and amphibians) having gone unstudied. Nonetheless, when a rare animal unexpectedly dies, there is no time to understand the fundamentals of biophysics. In these emergencies, it is necessary to rely on experience and the best data from taxonomically-related species. Fortunately, there are some general similarities among most species, which, for example, allow adequate post-thaw viability. Regardless, there is a priority for more information on biophysical traits and freezing tolerance of distinctive biomaterials, especially for oocytes and gonadal tissues, and even for common, domesticated animals. Our colleague, Dr John Critser was a pioneer in cryobiology, earning that moniker because of

  15. 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.

  16. 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

  17. Comparative study of the germination of Ulva prolifera gametes on various substrates

    NASA Astrophysics Data System (ADS)

    Geng, Huixia; Yan, Tian; Zhou, Mingjiang; Liu, Qing

    2015-09-01

    Since 2007, massive green tides have occurred every summer in the southern Yellow Sea (YS), China. They have caused severe ecological consequences and huge economic losses. Ulva prolifera originated from Subei Shoal of the YS was confirmed as causative species of the green tides. The Porphyra yezoensis aquaculture rafts in the Subei Shoal have been highly suspected to be the "seed bed" of the green tides, because U. prolifera abundantly fouled the Porphyra yezoensis aquaculture facilities. Besides, various habitats of aquaculture ponds along the Jiangsu coastline and mudflat in the Subei Shoal were proposed to be possible sources of green tides. To understand the "seed" of the green tides in the southern YS and mitigate the original biomass of the green tide, various materials used as substrates for the germination of U. prolifera gametes were tested in this study. Culture experiments showed the following: 1) materials used in the P. yezoensis rafts (plastic, bamboo, jute rope, plastic rope, nylon netting, and plastic netting) displayed a significantly higher germination rate than those associated with mudflats and aquaculture ponds (mud, sand and rock); 2) plastics were the best substrates for the germination of U. prolifera gametes; 3) poor germination was found on old fronds of U. prolifera,, and rubber showed inhibitory effect on germination. The success in germination on P. yezoensis rafts related materials supports the notion that these mariculture structures may be involved in acting as a seed bed for green tide macroalgae. The lack of germination on rubber surfaces may suggest one way to limit the proliferation of early stages of U. prolifera.

  18. Cryobanking of farm animal gametes and embryos as a means of conserving livestock genetics.

    PubMed

    Mara, L; Casu, Sara; Carta, A; Dattena, M

    2013-04-01

    In the last few decades, farm animal genetic diversity has rapidly declined, mainly due to changing market demands and intensification of agriculture. But, since the removal of single species can affect the functioning of global ecosystems, it is in the interest of international community to conserve the livestock genetics and to maintain biodiversity. Increasing awareness on the reduction of breed diversity has prompted global efforts for conservation of farm animal breeds. The goals of conservation are to keep genetic variation as gene combinations in a reversible form and to keep specific genes of interest. For this purpose two types of strategies are usually proposed: in situ and ex situ conservation. In situ conservation is the breed maintaining within the livestock production system, in its environment through the enhancement of its production characteristics. Ex situ in vivo conservation is the safeguard of live animals in zoos, wildlife parks, experimental farms or other specialized centres. Ex situ in vitro conservation is the preservation of genetic material in haploid form (semen and oocytes), diploid (embryos) or DNA sequences. In the last few years, ex situ in vitro conservation programs of livestock genetic resources have focused interest on cryopreservation of gametes, embryos and somatic cells as well as testis and ovarian tissues, effectively lengthening the genetic lifespan of individuals in a breeding program even after the death. However, although significant progress has been made in semen, oocytes and embryo cryopreservation of several domestic species, a standardized procedure has not been established yet. The aim of the present review is to describe the cryobanking purposes, the collection goals, the type of genetic material to store and the reproductive biotechnologies utilized for the cryopreservation of farm animal gametes and embryos.

  19. 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.

  20. Splitting theorem for Z2n -supermanifolds

    NASA Astrophysics Data System (ADS)

    Covolo, Tiffany; Grabowski, Janusz; Poncin, Norbert

    2016-12-01

    Smooth Z2n -supermanifolds have been introduced and studied recently. The corresponding sign rule is given by the 'scalar product' of the involved Z2n -degrees. It exhibits interesting changes in comparison with the sign rule using the parity of the total degree. With the new rule, nonzero degree even coordinates are not nilpotent, and even (resp., odd) coordinates do not necessarily commute (resp., anticommute) pairwise. The classical Batchelor-Gawȩdzki theorem says that any smooth supermanifold is diffeomorphic to the 'superization' ΠE of a vector bundle E. It is also known that this result fails in the complex analytic category. Hence, it is natural to ask whether an analogous statement goes through in the category of Z2n -supermanifolds with its local model made of formal power series. We give a positive answer to this question.

  1. 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

  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. Arabidopsis HAP2/GCS1 is a gamete fusion protein homologous to somatic and viral fusogens.

    PubMed

    Valansi, Clari; Moi, David; Leikina, Evgenia; Matveev, Elena; Graña, Martín; Chernomordik, Leonid V; Romero, Héctor; Aguilar, Pablo S; Podbilewicz, Benjamin

    2017-03-06

    Cell-cell fusion is inherent to sexual reproduction. Loss of HAPLESS 2/GENERATIVE CELL SPECIFIC 1 (HAP2/GCS1) proteins results in gamete fusion failure in diverse organisms, but their exact role is unclear. In this study, we show that Arabidopsis thaliana HAP2/GCS1 is sufficient to promote mammalian cell-cell fusion. Hemifusion and complete fusion depend on HAP2/GCS1 presence in both fusing cells. Furthermore, expression of HAP2 on the surface of pseudotyped vesicular stomatitis virus results in homotypic virus-cell fusion. We demonstrate that the Caenorhabditis elegans Epithelial Fusion Failure 1 (EFF-1) somatic cell fusogen can replace HAP2/GCS1 in one of the fusing membranes, indicating that HAP2/GCS1 and EFF-1 share a similar fusion mechanism. Structural modeling of the HAP2/GCS1 protein family predicts that they are homologous to EFF-1 and viral class II fusion proteins (e.g., Zika virus). We name this superfamily Fusexins: fusion proteins essential for sexual reproduction and exoplasmic merger of plasma membranes. We suggest a common origin and evolution of sexual reproduction, enveloped virus entry into cells, and somatic cell fusion.

  5. 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.

  6. Female and Male Gamete Mitochondria Are Distinct and Complementary in Transcription, Structure, and Genome Function

    PubMed Central

    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. PMID:24068653

  7. All males are not created equal: Fertility differences depend on gamete recognition polymorphisms in sea urchins

    PubMed Central

    Palumbi, Stephen R.

    1999-01-01

    Behaviors, morphologies, and genetic loci directly involved in reproduction have been increasingly shown to be polymorphic within populations. Explaining how such variants are maintained by selection is crucial to understanding the genetic basis of fertility differences, but direct tests of how alleles at reproductive loci affect fertility are rare. In the sea urchin genus Echinometra, the protein bindin mediates sperm attachment to eggs, evolves quickly, and is polymorphic within species. Eggs exposed to experimental sperm mixtures show strong discrimination on the basis of the males’ bindin genotype. Different females produce eggs that nonrandomly select sperm from different males, showing that variable egg–sperm interactions determine fertility. Eggs select sperm with a bindin genotype similar to their own, suggesting strong linkage between female choice and male trait loci. These experiments demonstrate that alleles at a single locus can have a strong effect on fertilization and that reproductive loci may retain functional polymorphisms through epistatic interactions between male and female traits. They also suggest that positive selection at gamete recognition loci like bindin involves strong selection within species on mate choice interactions. PMID:10535974

  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. Fertilization of Mouse Gametes in Vitro Using a Digital Microfluidic System.

    PubMed

    Huang, Hong-Yuan; Shen, Hsien-Hua; Chung, Lung-Yuan; Chung, Yu-Hsiang; Chen, Chih-Chen; Hsu, Chia-Hsien; Fan, Shih-Kang; Yao, Da-Jeng

    2015-12-01

    We demonstrated in vitro fertilization (IVF) using a digital microfluidic (DMF) system, so-called electrowetting on dielectric (EWOD). The DMF device was proved to be biocompatible and the DMF manipulation of a droplet was harmless to the embryos. This DMF platform was then used for the fertilization of mouse gametes in vitro and for embryo dynamic culture based on a dispersed droplet form. Development of the embryos was instantaneously recorded by a time-lapse microscope in an incubator. Our results indicated that increasing the number of sperms for IVF would raise the rate of fertilization. However, the excess of sperms in the 10 μL culture medium would more easily make the embryo dead during cell culture. Dynamic culture powered with EWOD can manipulate a single droplet containing mouse embryos and culture to the eight-cell stage. The fertilization rate of IVF demonstrated by DMF system was 34.8%, and about 25% inseminated embryos dynamically cultured on a DMF chip developed into an eight-cell stage. The results indicate that the DMF system has the potential for application in assisted reproductive technology.

  10. Would 'all-inclusive' compensation attract more gamete donors to balance their loss of anonymity?

    PubMed

    Craft, Ian; Thornhill, Alan

    2005-03-01

    The UK Government has determined that children born from egg donation have the same right to know their biological parent as adopted children on reaching the age of 18. There is concern as to the effect of loss of anonymity on egg donor recruitment, since a wait of 1 or 2 years is not unusual even under present circumstances. Some fertility programmes have introduced egg-sharing (involving 'subfertile donors') to circumvent the delays. However, with this method both the donor and the recipient may have reduced overall success. The shortage of sperm donors has led the Human Fertilisation and Embryology Authority (HFEA) to consider increasing the allowable expenses payment and a consultation exercise is underway to review payments and other issues for sperm, egg and embryo donors. Fundamental new initiatives regarding gamete donation need to be implemented to avoid further restrictions on an already unsatisfactory service. An 'all-inclusive' financial allowance is proposed for donors to promote donor recruitment and shorten the waiting time to treatment predicted to increase with the loss of anonymity.

  11. 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

  12. Transfer of intracolonial genetic variability through gametes in Acropora hyacinthus corals

    NASA Astrophysics Data System (ADS)

    Schweinsberg, M.; González Pech, R. A.; Tollrian, R.; Lampert, K. P.

    2014-03-01

    In recent years, the new phenomenon of intracolonial genetic variability within a single coral colony has been described. This connotes that coral colonies do not necessarily consist of only a single genotype, but may contain several distinct genotypes. Harboring more than one genotype could improve survival under stressful environmental conditions, e.g., climate change. However, so far it remained unclear whether the intracolonial genetic variability of the adult coral is also present in the gametes. We investigated the occurrence of intracolonial genetic variability in 14 mature colonies of the coral Acropora hyacinthus using eight microsatellite loci. A grid was placed over each colony before spawning, and the emerging egg/sperm bundles were collected separately in each grid. The underlying tissues as well as the egg/sperm bundles were genotyped to determine whether different genotypes were present. Within the 14 mature colonies, we detected 10 colonies with more than one genotype (intracolonial genetic variability). Four out of these 10 mature colonies showed a transfer of different genotypes via the eggs to the next generation. In two out of these four cases, we found additional alleles, and in the two other cases, we found only a subset of alleles in the unfertilized eggs. Our results suggest that during reproduction of A. hyacinthus, more than one genotype per colony is able to reproduce. We discuss the occurrence of different genotypes within a single coral colony and the ability for those to release eggs which are genetically distinct.

  13. Vertical transmission of Prunus necrotic ringspot virus: hitch-hiking from gametes to seedling.

    PubMed

    Amari, Khalid; Burgos, Lorenzo; Pallás, Vicente; Sánchez-Pina, Maria Amelia

    2009-07-01

    The aim of this work was to follow Prunus necrotic ringspot virus (PNRSV) infection in apricot reproductive tissues and transmission of the virus to the next generation. For this, an analysis of viral distribution in apricot reproductive organs was carried out at different developmental stages. PNRSV was detected in reproductive tissues during gametogenesis. The virus was always present in the nucellus and, in some cases, in the embryo sac. Studies within infected seeds at the embryo globular stage revealed that PNRSV infects all parts of the seed, including embryo, endosperm and testa. In the torpedo and bent cotyledon developmental stages, high concentrations of the virus were detected in the testa and endosperm. At seed maturity, PNRSV accumulated slightly more in the embryo than in the cotyledons. In situ hybridization showed the presence of PNRSV RNA in embryos obtained following hand-pollination of virus-free pistils with infected pollen. Interestingly, tissue-printing from fruits obtained from these pistils showed viral RNA in the periphery of the fruits, whereas crosses between infected pistils and infected pollen resulted in a total invasion of the fruits. Taken together, these results shed light on the vertical transmission of PNRSV from gametes to seedlings.

  14. SUPPRESSOR OF FRIGIDA (SUF4) Supports Gamete Fusion via Regulating Arabidopsis EC1 Gene Expression.

    PubMed

    Resentini, Francesca; Cyprys, Philipp; Steffen, Joshua G; Alter, Svenja; Morandini, Piero; Mizzotti, Chiara; Lloyd, Alan; Drews, Gary N; Dresselhaus, Thomas; Colombo, Lucia; Sprunck, Stefanie; Masiero, Simona

    2017-01-01

    The EGG CELL1 (EC1) gene family of Arabidopsis (Arabidopsis thaliana) comprises five members that are specifically expressed in the egg cell and redundantly control gamete fusion during double fertilization. We investigated the activity of all five EC1 promoters in promoter-deletion studies and identified SUF4 (SUPPRESSOR OF FRIGIDA4), a C2H2 transcription factor, as a direct regulator of the EC1 gene expression. In particular, we demonstrated that SUF4 binds to all five Arabidopsis EC1 promoters, thus regulating their expression. The down-regulation of SUF4 in homozygous suf4-1 ovules results in reduced EC1 expression and delayed sperm fusion, which can be rescued by expressing SUF4-β-glucuronidase under the control of the SUF4 promoter. To identify more gene products able to regulate EC1 expression together with SUF4, we performed coexpression studies that led to the identification of MOM1 (MORPHEUS' MOLECULE1), a component of a silencing mechanism that is independent of DNA methylation marks. In mom1-3 ovules, both SUF4 and EC1 genes are down-regulated, and EC1 genes show higher levels of histone 3 lysine-9 acetylation, suggesting that MOM1 contributes to the regulation of SUF4 and EC1 gene expression.

  15. "I am Your Mother and Your Father!" In Vitro Derived Gametes and the Ethics of Solo Reproduction.

    PubMed

    Cutas, Daniela; Smajdor, Anna

    2016-03-11

    In this paper, we will discuss the prospect of human reproduction achieved with gametes originating from only one person. According to statements by a minority of scientists working on the generation of gametes in vitro, it may become possible to create eggs from men's non-reproductive cells and sperm from women's. This would enable, at least in principle, the creation of an embryo from cells obtained from only one individual: 'solo reproduction'. We will consider what might motivate people to reproduce in this way, and the implications that solo reproduction might have for ethics and policy. We suggest that such an innovation is unlikely to revolutionise reproduction and parenting. Indeed, in some respects it is less revolutionary than in vitro fertilisation as a whole. Furthermore, we show that solo reproduction with in vitro created gametes is not necessarily any more ethically problematic than gamete donation-and probably less so. Where appropriate, we draw parallels with the debate surrounding reproductive cloning. We note that solo reproduction may serve to perpetuate reductive geneticised accounts of reproduction, and that this may indeed be ethically questionable. However, in this it is not unique among other technologies of assisted reproduction, many of which focus on genetic transmission. It is for this reason that a ban on solo reproduction might be inconsistent with continuing to permit other kinds of reproduction that also bear the potential to strengthen attachment to a geneticised account of reproduction. Our claim is that there are at least as good reasons to pursue research towards enabling solo reproduction, and eventually to introduce solo reproduction as an option for fertility treatment, as there are to do so for other infertility related purposes.

  16. 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

  17. 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.

  18. 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.

  19. The Role of Peroxisome Proliferator-Activated Receptors in the Development and Physiology of Gametes and Preimplantation Embryos

    PubMed Central

    Huang, Jaou-Chen

    2008-01-01

    In several species, a family of nuclear receptors, the peroxisome proliferator-activated receptors (PPARs) composed of three isotypes, is expressed in somatic cells and germ cells of the ovary as well as the testis. Invalidation of these receptors in mice or stimulation of these receptors in vivo or in vitro showed that each receptor has physiological roles in the gamete maturation or the embryo development. In addition, synthetic PPAR γ ligands are recently used to induce ovulation in women with polycystic ovary disease. These results reveal the positive actions of PPAR in reproduction. On the other hand, xenobiotics molecules (in herbicides, plasticizers, or components of personal care products), capable of activating PPAR, may disrupt normal PPAR functions in the ovary or the testis and have consequences on the quality of the gametes and the embryos. Despite the recent data obtained on the biological actions of PPARs in reproduction, relatively little is known about PPARs in gametes and embryos. This review summarizes the current knowledge on the expression and the function of PPARs as well as their partners, retinoid X receptors (RXRs), in germ cells and preimplantation embryos. The effects of natural and synthetic PPAR ligands will also be discussed from the perspectives of reproductive toxicology and assisted reproductive technology. PMID:18354728

  20. The formation of improved tetraploid population of red crucian carp x common carp hybrids by androgenesis.

    PubMed

    Duan, Wei; Qin, QinBo; Chen, Song; Liu, ShaoJun; Wang, Jing; Zhang, Chun; Sun, YuanDong; Liu, Yun

    2007-12-01

    Bisexual fertile diploid androgenetic individuals (A(0)) (2n=100) were formed by androgenesis. In this way, the diploid spermatozoa from male allotetraploid hybrids (AT) (4n=200) of red crucian carp (Carassius auratus red var.) (female) x common carp (Cyprinus carpio L.) (male) were used to fertilize the UV-treated haploid eggs of goldfish (Carassius auratus), and living androgenetic diploid fish were developed. The A(0) became sexually mature at the age of 2 years, and they fertilized with each other to form their offspring (A(1)). In this study, we observed the chromosomal number, gonadal structure and appearance of A(1) fish. The results are as follows: (1) In A(1), there were 85% tetraploids (A(1)-4n), 10% triploids (A(1)-3n) and 5% diploids (A(1)-2n), suggesting that diploid A(0) could produce diploid gametes. It was concluded that the formation of diploid gametes generated from diploid A(0) was probably related to the mechanism of pre-meiotic endoreduplication. (2) Among A(1), only A(1)-4n possessed normal ovaries and testes. The mature males of A1-4n produced white semen. Under the electron microscope, the head of diploid sperm generated by A(1)-4n was bigger than that of haploid sperm generated by red crucian carp. In the testes of the A(1)-4n, there were many mature normal spermatozoa with a head bearing plasma membrane and a tail having the typical structure of "9+2" microtubules. Between the head and the tail, there were some mitochondria. The ovaries of A(1)-4n developed well and mainly contained II, III and IV-stage oocytes. The IV-stage oocytes were surrounded by inner and outer follicular cells. The micropyle was observed on the oolemma of follicular cells. There were abundant yolks and plenty of endoplasmic reticulum in the cytoplasm of IV-stage oocytes. Because A(1)-2n and A(1)-3n were distant crossing diploid hybrids and triploid hybrids respectively, they possessed abnormal gonads, and no mature semen and eggs were observed. (3) Compared with

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

    PubMed

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

    2015-04-09

    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).

  2. 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.

  3. Membrane fusion triggers rapid degradation of two gamete-specific, fusion-essential proteins in a membrane block to polygamy in Chlamydomonas.

    PubMed

    Liu, Yanjie; Misamore, Michael J; Snell, William J

    2010-05-01

    The plasma membranes of gametes are specialized for fusion, yet, once fusion occurs, in many organisms the new zygote becomes incapable of further membrane fusion reactions. The molecular mechanisms that underlie this loss of fusion capacity (block to polygamy) remain unknown. During fertilization in the green alga Chlamydomonas, the plus gamete-specific membrane protein FUS1 is required for adhesion between the apically localized sites on the plasma membranes of plus and minus gametes that are specialized for fusion, and the minus-specific membrane protein HAP2 is essential for completion of the membrane fusion reaction. HAP2 (GCS1) family members are also required for fertilization in Arabidopsis, and for the membrane fusion reaction in the malaria organism Plasmodium berghei. Here, we tested whether Chlamydomonas gamete fusion triggers alterations in FUS1 and HAP2 and renders the plasma membranes of the cells incapable of subsequent fusion. We find that, even though the fusogenic sites support multi-cell adhesions, triploid zygotes are rare, indicating a fusion-triggered block to the membrane fusion reaction. Consistent with the extinction of fusogenic capacity, both FUS1 and HAP2 are degraded upon fusion. The rapid, fusion-triggered cleavage of HAP2 in zygotes is distinct from degradation occurring during constitutive turnover in gametes. Thus, gamete fusion triggers specific degradation of fusion-essential proteins and renders the zygote incapable of fusion. Our results provide the first molecular explanation for a membrane block to polygamy in any organism.

  4. Membrane fusion triggers rapid degradation of two gamete-specific, fusion-essential proteins in a membrane block to polygamy in Chlamydomonas

    PubMed Central

    Liu, Yanjie; Misamore, Michael J.; Snell, William J.

    2010-01-01

    The plasma membranes of gametes are specialized for fusion, yet, once fusion occurs, in many organisms the new zygote becomes incapable of further membrane fusion reactions. The molecular mechanisms that underlie this loss of fusion capacity (block to polygamy) remain unknown. During fertilization in the green alga Chlamydomonas, the plus gamete-specific membrane protein FUS1 is required for adhesion between the apically localized sites on the plasma membranes of plus and minus gametes that are specialized for fusion, and the minus-specific membrane protein HAP2 is essential for completion of the membrane fusion reaction. HAP2 (GCS1) family members are also required for fertilization in Arabidopsis, and for the membrane fusion reaction in the malaria organism Plasmodium berghei. Here, we tested whether Chlamydomonas gamete fusion triggers alterations in FUS1 and HAP2 and renders the plasma membranes of the cells incapable of subsequent fusion. We find that, even though the fusogenic sites support multi-cell adhesions, triploid zygotes are rare, indicating a fusion-triggered block to the membrane fusion reaction. Consistent with the extinction of fusogenic capacity, both FUS1 and HAP2 are degraded upon fusion. The rapid, fusion-triggered cleavage of HAP2 in zygotes is distinct from degradation occurring during constitutive turnover in gametes. Thus, gamete fusion triggers specific degradation of fusion-essential proteins and renders the zygote incapable of fusion. Our results provide the first molecular explanation for a membrane block to polygamy in any organism. PMID:20335357

  5. Expression of a type B RIFIN in Plasmodium falciparum merozoites and gametes

    PubMed Central

    2012-01-01

    Background The ability of Plasmodium falciparum to undergo antigenic variation, by switching expression among protein variants encoded by multigene families, such as var, rif and stevor, is key to the survival of this parasite in the human host. The RIFIN protein family can be divided into A and B types based on the presence or absence of a 25 amino acid motif in the semi-conserved domain. A particular type B RIFIN, PF13_0006, has previously been shown to be strongly transcribed in the asexual and sexual stages of P. falciparum in vitro. Methods Antibodies to recombinant PF13_0006 RIFIN were used in immunofluorescence and confocal imaging of 3D7 parasites throughout the asexual reproduction and sexual development to examine the expression of PF13_0006. Furthermore, reactivity to recombinant PF13_0006 was measured in plasma samples collected from individuals from both East and West African endemic areas. Results The PF13_0006 RIFIN variant appeared expressed by both released merozoites and gametes after emergence. 7.4% and 12.1% of individuals from East and West African endemic areas, respectively, carry plasma antibodies that recognize recombinant PF13_0006, where the antibody responses were more common among older children. Conclusions The stage specificity of PF13_0006 suggests that the diversity of RIFIN variants has evolved to provide multiple specialized functions in different stages of the parasite life cycle. These data also suggest that RIFIN variants antigenically similar to PF13_0006 occur in African parasite populations. PMID:23259643

  6. 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.

  7. Single photon ionization of van der Waals clusters with a soft x-ray laser: (SO2)n and (SO2)n(H2O)m

    NASA Astrophysics Data System (ADS)

    Dong, F.; Heinbuch, S.; Rocca, J. J.; Bernstein, E. R.

    2006-10-01

    van der Waals cluster (SO2)n is investigated by using single photon ionization of a 26.5eV soft x-ray laser. During the ionization process, neutral clusters suffer a small fragmentation because almost all energy is taken away by the photoelectron and a small part of the photon energy is deposited into the (SO2)n cluster. The distribution of (SO2)n clusters decreases roughly exponentially with increasing cluster size. The photoionization dissociation fraction of I[(SO2)n-1SO+]/I[(SO2)n+] decreases with increasing cluster size due to the formation of cluster. The metastable dissociation rate constants of (SO2)n+ are measured in the range of (0.6-1.5)×104s-1 for cluster sizes 5⩽n⩽16. Mixed SO2-H2O clusters are studied at different experimental conditions. At the condition of high SO2 concentration (20% SO2 partial pressure), (SO2)n + cluster ions dominate the mass spectrum, and the unprotonated mixed cluster ions (SO2)nH2O+ (1⩽n⩽5) are observed. At the condition of low SO2 concentration (5% SO2 partial pressure) (H2O)nH+ cluster ions are the dominant signals, and protonated cluster ions (SO2)(H2O)nH+ are observed. The mixed clusters, containing only one SO2 or H2O molecule, SO2(H2O)nH+ and (SO2)nH2O+ are observed, respectively.

  8. 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

  9. 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

  10. Single photon ionization of van der Waals clusters with a soft x-ray laser: (CO2)n and (CO2)n(H2O)m

    NASA Astrophysics Data System (ADS)

    Heinbuch, S.; Dong, F.; Rocca, J. J.; Bernstein, E. R.

    2006-10-01

    Pure neutral (CO2)n clusters and mixed (CO2)n(H2O)m clusters are investigated employing time of flight mass spectroscopy and single photon ionization at 26.5eV. The distribution of pure (CO2)n clusters decreases roughly exponentially with increasing cluster size. During the ionization process, neutral clusters suffer little fragmentation because almost all excess cluster energy above the vertical ionization energy is taken away by the photoelectron and only a small part of the photon energy is deposited into the (CO2)n cluster. Metastable dissociation rate constants of (CO2)n+ are measured in the range of (0.2-1.5)×104s-1 for cluster sizes of 5⩽n⩽16. Mixed CO2-H2O clusters are studied under different generation conditions (5% and 20% CO2 partial pressures and high and low expansion pressures). At high CO2 concentration, predominant signals in the mass spectrum are the (CO2)n + cluster ions. The unprotonated cluster ion series (CO2)nH2O+ and (CO2)n(H2O)2+ are also observed under these conditions. At low CO2 concentration, protonated cluster ions (H2O)nH+ are the dominant signals, and the protonated CO2(H2O)nH+ and unprotonated (H2O)n+ and (CO2)(H2O)n+ cluster ion series are also observed. The mechanisms and dynamics of the formation of these neutral and ionic clusters are discussed.

  11. 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

  12. 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

  13. Protection against De Novo Methylation Is Instrumental in Maintaining Parent-of-Origin Methylation Inherited from the Gametes

    PubMed Central

    Proudhon, Charlotte; Duffié, Rachel; Ajjan, Sophie; Cowley, Michael; Iranzo, Julian; Carbajosa, Guillermo; Saadeh, Heba; Holland, Michelle L.; Oakey, Rebecca J.; Rakyan, Vardhman K.; Schulz, Reiner; Bourc’his, Déborah

    2012-01-01

    Summary Identifying loci with parental differences in DNA methylation is key to unraveling parent-of-origin phenotypes. By conducting a MeDIP-Seq screen in maternal-methylation free postimplantation mouse embryos (Dnmt3L-/+), we demonstrate that maternal-specific methylation exists very scarcely at midgestation. We reveal two forms of oocyte-specific methylation inheritance: limited to preimplantation, or with longer duration, i.e. maternally imprinted loci. Transient and imprinted maternal germline DMRs (gDMRs) are indistinguishable in gametes and preimplantation embryos, however, de novo methylation of paternal alleles at implantation delineates their fates and acts as a major leveling factor of parent-inherited differences. We characterize two new imprinted gDMRs, at the Cdh15 and AK008011 loci, with tissue-specific imprinting loss, again by paternal methylation gain. Protection against demethylation after fertilization has been emphasized as instrumental in maintaining parent-of-origin methylation inherited from the gametes. Here we provide evidence that protection against de novo methylation acts as an equal major pivot, at implantation and throughout life. PMID:22902559

  14. 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.

  15. Induced pluripotent stem cell-derived gamete-associated proteins incite rejection of induced pluripotent stem cells in syngeneic mice.

    PubMed

    Kim, Eun-Mi; Manzar, Gohar; Zavazava, Nicholas

    2017-02-10

    The safety of induced pluripotent stem cells (iPSCs) in autologous recipients has been questioned after iPSCs, but not embryonic stem cells (ESCs), were reported to be rejected in syngeneic mice. This important topic has remained controversial because there has not been a mechanistic explanation for this phenomenon. Here, we hypothesize that iPSCs, but not ESCs, readily differentiate into gamete-forming cells that express meiotic antigens normally found in immune-privileged gonads. Because peripheral blood T cells are not tolerized to these antigens in the thymus, gamete-associated-proteins (GAPs) sensitize T cells leading to rejection. Here, we provide evidence that GAPs expressed in iPSC teratomas, but not in ESC teratomas, are responsible for the immunological rejection of iPSCs. Furthermore, silencing the expression of Stra8, 'the master regulator of meiosis', in iPSCs, using short hairpin RNA led to significant abrogation of the rejection of iPSCs, supporting our central hypothesis that GAPs expressed after initiation of meiosis in iPSCs were responsible for rejection. In contrast to iPSCs, iPSC-derivatives, such as haematopoietic progenitor cells, are able to engraft long-term into syngeneic recipients because they no longer express GAPs. Our findings, for the first time, provide a unifying explanation of why iPSCs, but not ESCs, are rejected in syngeneic recipients, ending the current controversy on the safety of iPSCs and their derivatives.

  16. 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.

  17. Infrared spectra of the Ne2-N2O, Ar2-N2O trimers

    NASA Astrophysics Data System (ADS)

    Rezaei, M.; Michaelian, K. H.; McKellar, A. R. W.; Moazzen-Ahmadi, N.

    2012-08-01

    Spectra of the van der Waals trimers Ar2-N2O and Ne2-N2O are studied in the region of the N2O ν1 fundamental (≈2220 cm-1) using a tunable quantum cascade laser to probe a pulsed supersonic expansion from a slit jet nozzle. Improved data are obtained for the dimers Ar-N2O and Ne-N2O, and the Q-branch of Ar3-N2O is tentatively assigned. The vibrational shifts for Nen-N2O are almost exactly linear for n = 0-2. However, for Arn-N2O the n = 2 band origin is slightly blue-shifted compared to the linear prediction, and the n = 3 origin (if correct) is more significantly blue-shifted (by 0.09 cm-1).

  18. 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

  19. Gamete cryobanks for laboratory research: developing a rapid and easy-to-perform protocol for the cryopreservation of the sea urchin Paracentrotus lividus (Lmk, 1816) spermatozoa.

    PubMed

    Fabbrocini, Adele; D'Adamo, Raffaele; Pelosi, Sergio; Oliveira, Luis F J; Silvestri, Fausto; Sansone, Giovanni

    2014-08-01

    Gamete cryopreservation is a biotechnology that can guarantee a continuous supply of gametes, regardless of the seasonal reproductive cycle. In this study we developed a protocol for the cryopreservation of the sea urchin Paracentrotuslividus spermatozoa, with a view to the creation of cryobanks of semen to be used as a model system in laboratory research and ecotoxicological tests. All the key phases of the procedure were separately considered and the effect on sperm motility was evaluated by means of computer assisted analysis. The best results were obtained using 7% dimethylsulfoxide in 1% NaCl plus 0.04 M trehalose as the extender, at a freezing rate of -20 °C/min. On thawing, in semen samples cryopreserved in accordance with this protocol the velocity parameters of the sub-population of rapid sperm (best performing spermatozoa) did not significantly differ from semen on collection; in addition also the fertilization ability was restored, and about 50% of normal developed plutei larvae were obtained by thawed semen. The developed protocol is rapid and easy-to-perform; moreover, the use of gametes from reared urchins makes it unnecessary to continuously collect specimens from natural populations, making this procedure a promising starting point for the creation of alternative and more sustainable methodologies in laboratory research on sea urchin gametes and embryos.

  20. 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.

  1. 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.

  2. First llama (Lama glama) pregnancy obtained after in vitro fertilization and in vitro culture of gametes from live animals.

    PubMed

    Trasorras, V; Baca Castex, C; Alonso, A; Giuliano, S; Santa Cruz, R; Arraztoa, C; Chaves, G; Rodríguez, D; Neild, D; Miragaya, M

    2014-07-01

    The aim of this study was to evaluate the developmental competence and pregnancy rate of llama hatched blastocysts produced in vitro using gametes from live animals and two different culture conditions. Fifteen adult females were superstimulated with 1500 IU of eCG, eleven (73%) responded to the treatment and were used as oocyte donors. Follicular aspiration was conducted by flank laparotomy. Semen collections were performed under general anesthesia by electroejaculation of the male. Sixty-six COCs were recovered from 77 aspirated follicles (86% recovery) and were randomly placed in Fertil-TALP microdroplets with the sperm suspension (20 × 10(6)live spermatozoa/ml). After 24 h, they were placed in SOFaa medium supplemented with FCS and randomly assigned to one of two culture conditions. Culture condition 1 (CC1) consisted of 6 days of culture (n=28) and culture condition 2 (CC2) consisted of renewing the culture medium every 48 h (n=35). In CC1, the blastocyst rate was 36% (10/28) and the hatched blastocyst rate was 28% (8/28) whereas in CC2, the blastocyst rate was 34% (12/35) and the hatched blastocyst rate was 20% (7/35) (p>0.05). No pregnancies were obtained after embryo transfer (ET) of CC1 blastocysts (0/8) while one pregnancy was obtained (1/7) after transferring a hatched blastocyst from CC2. Forty-two days after the ET, the pregnancy was lost. This study represents the first report of a pregnancy in the llama after intrauterine transfer of embryos produced by in vitro fertilization using gametes from live animals.

  3. Improvement of gamete quality and its short-term storage: an approach for biotechnology in laboratory fish.

    PubMed

    Yasui, G S; Senhorini, J A; Shimoda, E; Pereira-Santos, M; Nakaghi, L S O; Fujimoto, T; Arias-Rodriguez, L; Silva, L A

    2015-03-01

    In fish, in vitro fertilization is an important reproductive tool used as first step for application of others biotechniques as chromosome and embryo manipulation. In this study, we aimed to optimize gamete quality and their short-term storage from the yellowtail tetra Astyanax altiparanae, for future application in laboratory studies. Working with sperm, we evaluated the effects of spawning inducers (carp pituitary gland and Ovopel® [(D-Ala6, Pro9-NEt) - mGnRH+metoclopramide]) and the presence of female on sperm motility. Additionally, we developed new procedures for short-term storage of sperm and oocytes. Briefly, sperm motility was higher when male fish were treated with carp pituitary gland (73.1 ± 4.0%) or Ovopel® (79.5 ± 5.5%) when compared with the control group treated with 0.9% NaCl (55.6 ± 27.2%; P=0.1598). Maintenance of male fish with an ovulating female fish also improved sperm motility (74.4 ± 7.4%) when compared with untreated male fish (42.1 ± 26.1%; P=0.0018). Storage of sperm was optimized in modified Ringer solution, in which the sperm was kept motile for 18 days at 2.5°C. The addition of antibiotics or oxygen decreased sperm motility, but partial change of supernatant and the combination of those conditions improve storage ability of sperm. Fertilization ability of oocytes decreased significantly after storage for 30, 60 90 and 120 min at 5, 10, 15 and 20°C when compared with fresh oocytes (P=0.0471), but considering only the stored samples, the optimum temperature was 15°C. Those data describe new approaches to improve semen quality and gametes short-term storage in yellowtail tetra A. altiparanae and open new possibilities in vitro fertilization.

  4. 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

  5. Differential replication of two chloroplast genome forms in heteroplasmic Chlamydomonas reinhardtii gametes contributes to alternative inheritance patterns.

    PubMed

    Nishimura, Yoshiki; Stern, David B

    2010-08-01

    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 approximately 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.

  6. 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.

  7. 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.

  8. Infrared Spectra of the NE_2-N_2O, AR_2-N_2O Trimers

    NASA Astrophysics Data System (ADS)

    Rezaei, M.; Moazzen-Ahmadi, N.; Michaelian, K. H.; McKellar, A. R. W.

    2013-06-01

    Spectra of the van der Waals trimers Ar_2-N_2O and Ne_2-N_2O are studied in the region of the N_2O ν_1 fundamental (˜2224 cm^{-1}) using a tunable quantum cascade laser to probe a pulsed supersonic expansion from a slit jet nozzle. Improved data are also obtained for the dimers Ar-N_2O and Ne-N_2O, with the latter representing a significant improvement on the best previous results. As well, a feature in the spectrum is tentatively assigned as the Q-branch of Ar_3-N_2O. The observed vibrational shifts for Ne_n-N_2O are almost exactly linear for n = 0-2. However, for Ar_n-N_2O the n = 2 band origin is slightly blue-shifted compared to the linear prediction, and the n = 3 origin (if correct) is more significantly blue-shifted (by 0.09 cm^{-1}).

  9. 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…

  10. Magnetic, electronic and optical properties of different graphene, BN and BC2N nanoribbons

    NASA Astrophysics Data System (ADS)

    Guerra, T.; Leite, L.; Azevedo, S.; de Lima Bernardo, B.

    2017-04-01

    Graphene nanoribbons are predicted to be essential components in future nanoelectronics. The size, edge type, form, arrangement of atoms and width of nanoribbons drastically change their properties. However, magnetic, electronic and optical properties of armchair, chevron and sawtooth of graphene, BN and BC2N nanoribbons are not fully understood so far. Here, we make use of first-principles calculations based on the density functional theory (DFT) to investigate the structural, magnetic, electronic and optical properties of nanoribbons of graphene, boron nitride and BC2N with armchair edge, chevron-type and sawtooth forms. The lowest formation energies were found for the armchair and chevron nanoribbons of graphene and boron nitride. We have shown that the imbalance of carbon atoms between different sublattices generates a net magnetic moment. Chevron-type nanoribbons of BC2N and graphene showed a band gap comparable with silicon, and a high light absorption in the visible spectrum when compared to the other configurations.

  11. 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.

  12. The structure of the O2-N2O complex.

    PubMed

    Salmon, Steven R; Lane, Joseph R

    2015-09-28

    We have investigated the lowest energy structures and interaction energies of the oxygen nitrous oxide complex (O2-N2O) using explicitly correlated coupled cluster theory. We find that the intermolecular potential energy surface of O2-N2O is very flat, with two minima of comparable energy separated by a low energy first order saddle point. Our results are able to conclusively distinguish between the two sets of experimental geometric parameters for O2-N2O that were previously determined from rotationally resolved infrared spectra. The global minimum structure of O2-N2O is therefore found to be planar with a distorted slipped parallel structure. Finally, we show that the very flat potential energy surface of O2-N2O is problematic when evaluating vibrational frequencies with a numerical Hessian and that consideration should be given as to whether results might change if the step-size is varied.

  13. 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

  14. Season-dependent effects of elevated temperature on stress biomarkers, energy metabolism and gamete development in mussels.

    PubMed

    Múgica, M; Sokolova, I M; Izagirre, U; Marigómez, I

    2015-02-01

    In coastal areas, sessile species can be severely affected by thermal stress associated to climate change. Presently, the effect of elevated temperature on metabolic, cellular and tissue-level responses of mussels was determined to assess whether the responses vary seasonally with seawater temperature and reproductive stage. Mussels were collected in fall, winter and summer, and (a) maintained at 16, 12, and 20 °C respectively or (b) subject to gradual temperature elevation for 8 days (+1 °C per day; from 16 to 24 °C in fall, from 12 to 20 °C in winter and from 20 to 28 °C in summer) and further maintained at 24 °C (fall), 20 °C (winter) and 28 °C (summer) for the following 6 days. Temperature elevation induced membrane destabilization, lysosomal enlargement, and reduced the aerobic scope in fall and summer whereas in winter no significant changes were found. Changes at tissue-level were only evident at 28 °C. Gamete development was impaired irrespective of season. Since the threshold of negative effects of warming was close to ambient temperatures in summer (24 °C or above) studied mussel populations would be vulnerable to the global climate change.

  15. 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

  16. Control of DEMETER DNA demethylase gene transcription in male and female gamete companion cells in Arabidopsis thaliana

    PubMed Central

    Park, Jin-Sup; Frost, Jennifer M.; Park, Kyunghyuk; Ohr, Hyonhwa; Park, Guen Tae; Kim, Seohyun; Eom, Hyunjoo; Lee, Ilha; Brooks, Janie S.; Fischer, Robert L.; Choi, Yeonhee

    2017-01-01

    The DEMETER (DME) DNA glycosylase initiates active DNA demethylation via the base-excision repair pathway and is vital for reproduction in Arabidopsis thaliana. DME-mediated DNA demethylation is preferentially targeted to small, AT-rich, and nucleosome-depleted euchromatic transposable elements, influencing expression of adjacent genes and leading to imprinting in the endosperm. In the female gametophyte, DME expression and subsequent genome-wide DNA demethylation are confined to the companion cell of the egg, the central cell. Here, we show that, in the male gametophyte, DME expression is limited to the companion cell of sperm, the vegetative cell, and to a narrow window of time: immediately after separation of the companion cell lineage from the germline. We define transcriptional regulatory elements of DME using reporter genes, showing that a small region, which surprisingly lies within the DME gene, controls its expression in male and female companion cells. DME expression from this minimal promoter is sufficient to rescue seed abortion and the aberrant DNA methylome associated with the null dme-2 mutation. Within this minimal promoter, we found short, conserved enhancer sequences necessary for the transcriptional activities of DME and combined predicted binding motifs with published transcription factor binding coordinates to produce a list of candidate upstream pathway members in the genetic circuitry controlling DNA demethylation in gamete companion cells. These data show how DNA demethylation is regulated to facilitate endosperm gene imprinting and potential transgenerational epigenetic regulation, without subjecting the germline to potentially deleterious transposable element demethylation. PMID:28130550

  17. Secondary use of empirical research data in medical ethics papers on gamete donation: forms of use and pitfalls.

    PubMed

    Provoost, Veerle

    2015-03-01

    This paper aims to provide a description of how authors publishing in medical ethics journals have made use of empirical research data in papers on the topic of gamete or embryo donation by means of references to studies conducted by others (secondary use). Rather than making a direct contribution to the theoretical methodological literature about the role empirical research data could play or should play in ethics studies, the focus is on the particular uses of these data and the problems that can be encountered with this use. In the selection of papers examined, apart from being used to describe the context, empirical evidence was mainly used to recount problems that needed solving. Few of the authors looked critically at the quality of the studies they quoted, and several instances were found of empirical data being used poorly or inappropriately. This study provides some initial baseline evidence that shows empirical data, in the form of references to studies, are sometimes being used in inappropriate ways. This suggests that medical ethicists should be more concerned about the quality of the empirical data selected, the appropriateness of the choice for a particular type of data (from a particular type of study) and the correct integration of this evidence in sound argumentation. Given that empirical data can be misused also when merely cited instead of reported, it may be worthwhile to explore good practice requirements for this type of use of empirical data in medical ethics.

  18. New pH-buffering system for media utilized during gamete and embryo manipulations for assisted reproduction.

    PubMed

    Swain, Jason E; Pool, Thomas B

    2009-06-01

    Maintenance of stable pH is important for optimizing gamete and embryo culture. One method to stabilize pH entails using zwitterionic buffers in IVF handling media used outside the laboratory incubator. Current handling media utilize single buffers, such as MOPS or HEPES. However, the use of a single buffer limits the ability to adjust the range of buffering capacity. Furthermore, changes in temperature alter buffering of these compounds. Therefore, traditional IVF handling media utilizing a single buffer may not provide ideal pH buffering. This study reports that combining multiple buffers, such as HEPES, MOPS and DIPSO, into a single medium in various ratios gives the ability to shift the effective buffering range to cover a specific pH. Additionally, by combining various buffers, it is possible to expand pH buffering over a range of temperatures, while simultaneously reducing the absolute concentration of individual buffers, thereby reducing or alleviating toxicity concerns. This report verifies that DIPSO, MOPS and HEPES, and their combinations, support embryo development. Therefore, utilization of bi- and tri-buffered media, containing a mixture of HEPES, MOPS or DIPSO, offers advantages compared with media containing HEPES or MOPS alone, and may be used for procedures such as oocyte retrieval, intracytoplasmic sperm injection, embryo transfer and cryopreservation.

  19. Fertilization success of sterlet Acipenser ruthenus and Siberian sturgeon Acipenser baerii gametes under conditions of heterospecific mating.

    PubMed

    Havelka, M; Šachlová, H; Shaliutina-Kolešová, A; Rodina, M

    2016-11-01

    Species may be prevented from interspecific hybridization by a number of different reproductive barriers that operate precopulatory and postcopulatory. In situation, when natural precopulatory reproductive barriers are affected by anthropogenic factors, postcopulatory reproductive barriers may be important for maintaining gametic isolation and hence preventing interspecific hybridization. This is highly topical in sturgeon (order Acipenseriformes) which exhibits remarkable ease of interspecific hybridization. The objectives of the present study were to evaluate the fertilization success of Acipenser ruthenus and Acipenser baerii spermatozoa under the interspecific competitive conditions and assessed, whether their spermatozoa tend to differentially fertilize eggs of conspecifics. We set up several in vitro fertilization experiments: (i) pooled eggs of both species were fertilized by sperm of each species separately; (ii) eggs of each species were fertilized by pooled sperm; (iii) pooled eggs were fertilized by pooled sperm and (iv) purebred and hybrid control groups. Using parental assignment by molecular markers, we found that when these species competed in pooled sperm, 78.9% of progeny were sired by A. ruthenus and 21.1% by A. baerii, demonstrating higher fertilization success for the former, irrespective of conspecificity of fertilized eggs. When pooled eggs were inseminated by A. ruthenus or A. baerii sperm separately, progeny almost equally comprised hybrid and purebred individuals. Hence, neither A. ruthenus nor A. baerii eggs showed a tendency to biased fertilization by spermatozoa of conspecific males. These findings together show that there may not be postcopulatory mechanisms preventing hybridization between A. ruthenus and A. baerii.

  20. Control of DEMETER DNA demethylase gene transcription in male and female gamete companion cells in Arabidopsis thaliana.

    PubMed

    Park, Jin-Sup; Frost, Jennifer M; Park, Kyunghyuk; Ohr, Hyonhwa; Park, Guen Tae; Kim, Seohyun; Eom, Hyunjoo; Lee, Ilha; Brooks, Janie S; Fischer, Robert L; Choi, Yeonhee

    2017-02-21

    The DEMETER (DME) DNA glycosylase initiates active DNA demethylation via the base-excision repair pathway and is vital for reproduction in Arabidopsis thaliana DME-mediated DNA demethylation is preferentially targeted to small, AT-rich, and nucleosome-depleted euchromatic transposable elements, influencing expression of adjacent genes and leading to imprinting in the endosperm. In the female gametophyte, DME expression and subsequent genome-wide DNA demethylation are confined to the companion cell of the egg, the central cell. Here, we show that, in the male gametophyte, DME expression is limited to the companion cell of sperm, the vegetative cell, and to a narrow window of time: immediately after separation of the companion cell lineage from the germline. We define transcriptional regulatory elements of DME using reporter genes, showing that a small region, which surprisingly lies within the DME gene, controls its expression in male and female companion cells. DME expression from this minimal promoter is sufficient to rescue seed abortion and the aberrant DNA methylome associated with the null dme-2 mutation. Within this minimal promoter, we found short, conserved enhancer sequences necessary for the transcriptional activities of DME and combined predicted binding motifs with published transcription factor binding coordinates to produce a list of candidate upstream pathway members in the genetic circuitry controlling DNA demethylation in gamete companion cells. These data show how DNA demethylation is regulated to facilitate endosperm gene imprinting and potential transgenerational epigenetic regulation, without subjecting the germline to potentially deleterious transposable element demethylation.

  1. Effect of co-doping nano-silica filler and N-methyl- N-propylpiperidinium bis(trifluoromethanesulfonyl)imide into polymer electrolyte on Li dendrite formation in Li/poly(ethylene oxide)-Li(CF 3SO 2) 2N/Li

    NASA Astrophysics Data System (ADS)

    Liu, S.; Wang, H.; Imanishi, N.; Zhang, T.; Hirano, A.; Takeda, Y.; Yamamoto, O.; Yang, J.

    Lithium metal dendrite growth in Li/poly (ethylene oxide)-lithium bis (trifluoromethanesulfonyl) imide (PEO 18LiTFSI), nano-silica, and N-methyl- N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI) composite solid polymer electrolyte/Li was investigated by direct in situ observation. The dendrite onset time decreased with increasing current density and deviated from Sand's law in the current density range of 0.1-0.5 mA cm -2 at 60 °C. Lithium dendrite formation was not observed until 46 h of polarization at 0.5 mA cm -2 and 60 °C, which is a significant improvement compared to that observed in Li/(PEO 18LiTFSI)/Li, where the dendrite formation was observed after 15 h polarization at 0.5 mA cm -2 and 60 °C. The suppression of dendrite formation could be explained by the electrical conductivity enhancement and decrease of the interface resistance between Li and the polymer electrolyte by the introduction of both nano-SiO 2 and PP13TFSI into PEO 18LiTFSI. The electrical conductivity of 4.96 × 10 -4 S cm -1 at 60 °C was enhanced to 7.6 × 10 -4 S cm -1, and the interface resistance of Li/PEO 18LiTFSI/Li of 248 Ω cm 2 was decreased to 74 Ω cm 2 by the addition of both nano-SiO 2 and PP13TFSI into PEO 18LiTFSI.

  2. 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

  3. 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.

  4. 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

  5. Barriers to cross-fertilization between populations of a widely dispersed polychaete species are unlikely to have arisen through gametic compatibility arms-races.

    PubMed

    Styan, Craig A; Kupriyanova, Elena; Havenhand, Jon N

    2008-12-01

    Although there are theoretical reasons to suspect that gametic incompatibility may develop readily among populations of broadcast spawning marine invertebrates, there have been very few studies documenting geographic patterns of interpopulation incompatibility for any species. To address this we determined how successfully individuals of the intertidal serpulid polychaete, Galeolaria caespitosa, can cross-fertilize within and among populations from across temperate Australia. Fertilization assays revealed asymmetrical differences between very distantly located populations from different coasts, with near-complete incompatibility between eggs from Sydney with sperm from Adelaide, but the reverse cross (Adelaide eggs, Sydney sperm) was reasonably compatible. Although that pattern was congruent with a clear difference in Cytochrome B sequences between worms on the south and east coasts of Australia, we also detected some indication of interpopulation incompatibility within the genetic grouping on east coast, between two populations separated by only 220 km. We then assessed whether commonly proposed gametic compatibility arms-races could account for these patterns. Our results suggest reduced gametic compatibility may reduce a female's maximum fertilization potential, resulting in a cost to this potential mechanism for reducing polyspermy. Consequently, the apparently rapid development of reproductive barriers here seems unlikely to have been driven by arms-races involving sexual conflict over fertilization rate.

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

    PubMed

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

    2014-12-01

    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.

  7. Superhard cubic BC2N compared to diamond.

    PubMed

    Zhang, Yi; Sun, Hong; Chen, Changfeng

    2004-11-05

    Recent experiments claimed successful synthesis of cubic boron-carbonitride compounds BC2N with an extreme hardness second only to diamond. In the present Letter, we examine the ideal strength of cubic BC2N using first-principles calculations. Our results reveal that, despite the large elastic parameters, compositional anisotropy and strain dependent bonding character impose limitation on their strength. Consequently, the hardness of the optimal BC2N structure is predicted to be lower than that of cubic BN, the second hardest material known. The measured extreme hardness of BC2N nanocomposites is most likely due to the nanocrystalline size effect and the bonding to the surrounding amorphous carbon matrix. This may prove to be a general rule useful in the quest for new superhard covalent materials.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. Electronic, elastic, and optical properties of monolayer BC2N

    NASA Astrophysics Data System (ADS)

    Jiao, Lina; Hu, Meng; Peng, Yusi; Luo, Yanting; Li, Chunmei; Chen, Zhiqian

    2016-12-01

    The structural stability, electronic structure, elasticity, and optical properties of four types of monolayer BC2N have been investigated from first principles using calculation based on density functional theory. The results show that the structural stability of BC2N increases with the number of C-C and B-N bonds. By calculating the two-dimensional Young's modulus, shear modulus, Poisson's ratio, and shear anisotropic factors in different directions, four structures present various anisotropies and the most stable structure is almost isotropic. For C-type BC2N, the values of two-dimensional Young's modulus, shear modulus, and bulk modulus (309, 128, 195 GPa m-1), are smaller than those of graphene (343, 151, 208) but bigger than those of h-BN (286, 185, 116). Furthermore, the dielectric function, refractive index, reflectivity, absorption coefficient, and energy loss spectrum are also calculated to investigate the mechanism underpinning the optical transitions in BC2N, revealing monolayer BC2N as a candidate window material.

  13. 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.

  14. 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.

  15. [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

  16. 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.

  17. 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

  18. 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.

  19. Photodissociation dynamics of IBr(-)(CO(2))(n), n<15.

    PubMed

    Sanford, Todd; Han, Sang-Yun; Thompson, Matthew A; Parson, Robert; Lineberger, W Carl

    2005-02-01

    We report the ionic photoproducts produced following photoexcitation of mass selected IBr(-)(CO(2))(n), n=0-14, cluster ions at 790 and 355 nm. These wavelengths provide single state excitation to two dissociative states, corresponding to the A(') (2)Pi(1/2) and B 2 (2)Sigma(1/2) (+) states of the IBr(-) chromophore. Excitation of these states in IBr(-) leads to production of I(-)+Br and Br(-)+I( *), respectively. Potential energy curves for the six lowest electronic states of IBr(-) are calculated, together with structures for IBr(-)(CO(2))(n), n=1-14. Translational energy release measurements on photodissociated IBr(-) determine the I-Br(-) bond strength to be 1.10+/-0.04 eV; related measurements characterize the A(') (2)Pi(1/2)<--X (2)Sigma(1/2) (+) absorption band. Photodissociation product distributions are measured as a function of cluster size following excitation to the A(') (2)Pi(1/2) and B 2 (2)Sigma(1/2) (+) states. The solvent is shown to drive processes such as spin-orbit relaxation, charge transfer, recombination, and vibrational relaxation on the ground electronic state. Following excitation to the A(') (2)Pi(1/2) electronic state, IBr(-)(CO(2))(n) exhibits size-dependent cage fractions remarkably similar to those observed for I(2) (-)(CO(2))(n). In contrast, excitation to the B 2 (2)Sigma(1/2) (+) state shows extensive trapping in excited states that dominates the recombination behavior for all cluster sizes we investigated. Finally, a pump-probe experiment on IBr(-)(CO(2))(8) determines the time required for recombination on the ground state following excitation to the A(') state. While the photofragmentation experiments establish 100% recombination in the ground electronic state for this and larger IBr(-) cluster ions, the time required for recombination is found to be approximately 5 ns, some three orders of magnitude longer than observed for the analogous I(2) (-) cluster ion. Comparisons are made with similar experiments carried out on I(2

  20. Optimizing the culture environment in the IVF laboratory: impact of pH and buffer capacity on gamete and embryo quality.

    PubMed

    Swain, Jason E

    2010-07-01

    Supplying and maintaining appropriate culture conditions is critical to minimize stress imposed upon gametes and embryos and to optimize the in-vitro environment. One parameter that requires close scrutiny in this endeavour is pH. Though embryos have a limited ability to regulate their internal pH (pH(i)), oocytes lack robust mechanisms. Thus, careful attention to external pH (pH(e)) of culture media is imperative in IVF. Ability to withstand deviations in hydrogen ion concentration varies depending on culture conditions, as well as laboratory procedures. Cryopreserved--thaw--thawed embryos, as well as denuded oocytes, are especially susceptible to perturbations in pH(e). Therefore, proper setting, monitoring and stabilizing of pH(e) during IVF laboratory procedures is a crucial component of a rigorous quality control programme. Here, importance of both pH(i) and pH(e) in respect to gamete and embryo quality are discussed. Furthermore, factors influencing selection of pH(e), as well as emerging methods to stabilize pH(e) in the IVF laboratory are detailed.

  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. 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.

  3. 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.

  4. 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).

  5. 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.

  6. 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.

  7. 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.

  8. Identification and localization of the sperm CRISP family protein CiUrabin involved in gamete interaction in the ascidian Ciona intestinalis.

    PubMed

    Yamaguchi, Akira; Saito, Takako; Yamada, Lixy; Taniguchi, Hisaaki; Harada, Yoshito; Sawada, Hitoshi

    2011-07-01

    Ascidians are hermaphrodites, and most release sperm and eggs nearly simultaneously. Many species, including Halocynthia roretzi and Ciona intestinalis, are self-sterile. We previously reported that the interaction between a 12 EGF-like repeat-containing vitelline-coat (VC) protein, HrVC70, and a sperm GPI-anchored CRISP, HrUrabin, in lipid rafts plays a key role in self-/nonself-recognizable gamete interaction in H. roretzi. On the other hand, we recently identified two pairs of polymorphic genes responsible for self-incompatibility in C. intestinalis by positional cloning: The sperm polycystin 1-like receptors s-Themis-A/B and its fibrinogen-like ligand v-Themis-A/B on the VC. However, it is not known if the orthologs of HrVC70 and HrUrabin also participate in gamete interaction in C. intestinalis since they are from different orders. Here, we tested for a C. intestinalis ortholog (CiUrabin) of HrUrabin by searching the genome database and proteomes of sperm lipid rafts. The identified CiUrabin belongs to the CRISP family, with a PR domain and a GPI-anchor-attachment site. CiUrabin appears to be specifically expressed in the testis and localized at the surface of the sperm head, as revealed by Northern blotting and immunocytochemistry, respectively. The specific interaction between CiVC57, a C. intestinalis ortholog of HrVC70, and CiUrabin was confirmed by Far Western analysis, similarly to the interaction between HrVC70 and HrUrabin. The molecular interaction between CiVC57 and CiUrabin may be involved in the primary binding of sperm to the VC prior to the allorecognition process, mediated by v-Themis-A/B and s-Themis-A/B, during fertilization of C. intestinalis.

  9. A novel marsupial pri-miRNA transcript has a putative role in gamete maintenance and defines a vertebrate miRNA cluster paralogous to the miR-15a/miR-16-1 cluster.

    PubMed

    Au, Phil Chi Khang; Frankenberg, Stephen; Selwood, Lynne; Familari, Mary

    2011-10-01

    Successful maintenance, survival and maturation of gametes rely on bidirectional communication between the gamete and its supporting cells. Before puberty, factors from the gamete and its supporting cells are necessary for spermatogonial stem cell and primordial follicle oocyte maintenance. Following gametogenesis, gametes rely on factors and nutrients secreted by cells of the reproductive tracts, the epididymis and/or oviduct, to complete maturation. Despite extensive studies on female and male reproduction, many of the molecular mechanisms of germ cell maintenance remain relatively unknown, particularly in marsupial species. We present the first study and characterisation of a novel primary miRNA transcript, pri-miR-16c, in the marsupial, the stripe-faced dunnart. Bioinformatic analysis showed that its predicted processed miRNA - miR-16c - is present in a wide range of vertebrates, but not eutherians. In situ hybridisation revealed dunnart pri-miR-16c expression in day 4 (primordial germ cells) and day 7 (oogonia) pouch young, in primary oocytes and follicle cells of primordial follicles but then only in follicle cells of primary, secondary and antral follicles in adult ovaries. In the adult testis, pri-miR-16c transcripts were present in the cytoplasm of spermatogonial cells. The oviduct and the epididymis both showed expression, but not any other somatic tissues examined or conceptuses during early embryonic development. This pattern of expression suggests that pri-miR-16c function may be associated with gamete maintenance, possibly through mechanisms involving RNA transfer, until the zygote enters the uterus at the pronuclear stage.

  10. 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.

  11. 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.

  12. Multiphoton tomography, transfection, and nanosurgery with <2-nJ, 80-MHz femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten

    2004-06-01

    Biomedical applications of low-energy (< 2nJ) near infrared (NIR) femtosecond laser pulses provided by compact, turn-key Ti:sapphire lasers are presented in this review. Applications include (i) ultrahigh resolution optical diagnostics ("optical biopsies"), (ii) gene therapy by optical targeted transfection of cells, and (iii) ultraprecise laser therapy ("nanosurgery"). The novel femtosecond laser system DermaInspec (JenLab GmbH) enables for the first time in vivo deep tissue imaging of intracellular compartments with submicron spatial and picosecond temporal resolution in patients with dermatological disorders. Using the system FemtOcut, intracellular surgery, optical gene transfer, and intraocular refractive surgery can be performed. The major process behind the diagnostical and therapeutical laser effects is non-resonant multiphoton absorption which results in two-photon autofluorescence and second harmonic generation at transient intensities of GW/cm2 as well as multiphoton ionization and plasma formation at TW/cm2 intensities, respectively.

  13. 1,3-Dihydroxyacetone in Sagittarius B2(N-LMH): The First Interstellar Ketose

    NASA Astrophysics Data System (ADS)

    Widicus Weaver, Susanna L.; Blake, Geoffrey A.

    2005-05-01

    We present here the results of an initial search for 1,3-dihydroxyacetone [or DHA, CO(CH2OH)2], the simplest ketose monosaccharide, toward the Sagittarius B2(N-LMH) hot core. Nine possible DHA emission lines have been observed with the Caltech Submillimeter Observatory, from which a rotational excitation temperature of 220+/-65 K and a beam-averaged column density of (4.9+/-2.2)×1015 cm-2 are derived. If confirmed by additional observations, DHA would be among the most abundant complex molecules yet detected. DHA is not considered in any existing grain mantle or molecular cloud chemical model, highlighting the need for a more detailed investigation of the formation of prebiotic compounds in hot cores.

  14. Dipole polarizabilities of trimetallic nitride endohedral fullerenes M 3N@C 2n (M = Sc and Y; 2 n = 68-98)

    NASA Astrophysics Data System (ADS)

    He, Jiangang; Wu, Kechen; Sa, Rongjian; Li, Qiaohong; Wei, Yongqin

    2009-06-01

    The electronic structures and static dipole polarizabilities of M 3N@C 2n fullerenes (M = Sc and Y; 2 n = 68-98) were studied by using density functional theory. Unlike nonmetal endohedral fullerenes, M 3N@C 2n show smaller static dipole polarizabilities than the corresponding C 2n ones do. It is because the induced electric field of carbon cages is reduced by inserting M 3N cluster. The mean dipole polarizabilities of M 3N@C 2n fullerenes were found to correlate closely to their chemical hardness and electron delocalization volume. The refractive indexes of the face-centered-cubic crystals assembled by M 3N@C 2n fullerenes were also estimated.

  15. 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.

  16. An ab initio molecular orbital study of the reaction NH 2+NO → H 2+N 2O

    NASA Astrophysics Data System (ADS)

    Baker, Lane A.; Su, Shujun

    1998-03-01

    Potential energy surface of the reaction NH 2+NO → H 2+N 2O has been studied at several high levels of ab initio molecular orbital theory. The reaction pathway involves initially the formation without a barrier of a twisted non-planar H 2N-NO nitrosamine intermediate, and a C s symmetry transition state, followed by a dihydrogen H 2 elimination to form the products. The reaction path bifurcates before the transition state. At MP4(SDTQ)/6-311G(2d,p)//CASSCF/6-31G(d,p) level of theory, the reaction barrier for this path is found to be +33.7 kcal/mol.

  17. 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.

  18. Environmental concentrations of irgarol, diuron and S-metolachlor induce deleterious effects on gametes and embryos of the Pacific oyster, Crassostrea gigas.

    PubMed

    Mai, Huong; Morin, Bénédicte; Pardon, Patrick; Gonzalez, Patrice; Budzinski, Hélène; Cachot, Jérôme

    2013-08-01

    Irgarol and diuron are the most representative "organic booster biocides" that replace organotin compounds in antifouling paints, and metolachlor is one of the most extensively used chloroacetamide herbicides in agriculture. The toxicity of S-metolachlor, irgarol and diuron was evaluated in Pacific oyster (Crassostrea gigas) gametes or embryos exposed to concentrations of pesticides ranging from 0.1× to 1000×, with 1× corresponding to environmental concentrations of the three studied pesticides in Arcachon Bay (France). Exposures were performed on (1) spermatozoa alone (2) oocytes alone and (3) both spermatozoa and oocytes, and adverse effects on fertilization success and offspring development were recorded. The results showed that the fertilizing capacity of spermatozoa was significantly affected after gamete exposure to pesticide concentrations as low as 1× of irgarol and diuron and 10× of metolachlor. The offspring obtained from pesticide-exposed spermatozoa displayed a dose-dependent increase in developmental abnormalities. In contrast, treating oocytes with pesticide concentrations up to 10× did not alter fertilization rate and offspring quality. However, a significant decline in fertilization success and increase in abnormal D-larvae prevalence were observed at higher concentrations 10× (0.1 μg L(-1)) for S-metolachlor and 100× for irgarol (1.0 μg L(-1)) and diuron (4.0 μg L(-1)). Irgarol, diuron and S-metolachlor also induced a dose-dependent increase in abnormal D-larvae prevalence when freshly fertilized embryos were treated with pesticide concentrations as low as concentration of 1× (0.01 μg L(-1) for irgarol or S-metolachlor, and 0.04 μg L(-1) for diuron). The two bioassays on C. gigas spermatozoa and embryos displayed similar sensitivities to the studied pesticides while oocytes were less sensitive. Diuron, irgarol and S-metolachlor induced spermiotoxicity and embryotoxicity at environmentally relevant concentrations and therefore might be

  19. A divergent strategy for covalently-tethered (tpy)2Ru(II) systems based on Rh2(N,N'-diphenylbenzamidinates)4.

    PubMed

    Cooke, Michael W; Santoni, Marie-Pierre; Hanan, Garry S; Proust, Anna; Hasenknopf, Bernold

    2009-05-21

    A tetra Ru(II) bis(terpyridine) complex has been synthesized from Rh2(N,N'-diphenyl-4-bromobenzamidinate)4 in excellent yield using a modified Buchwald-Hartwig C-N bond forming protocol followed by efficient amide bond formation.

  20. Luminescence measurements of Xe+ + N2 and Xe2+ + N2 hyperthermal charge transfer collisions

    NASA Astrophysics Data System (ADS)

    Prince, Benjamin D.; Chiu, Yu-Hui

    2011-09-01

    Luminescence spectra are recorded for collisions between Xe+/Xe2+ and molecular nitrogen at energies ranging from 4.5 to 316 eV in the center-of-mass frame. In the Xe+ + N2 collision system, evidence for luminescent charge-transfer products is only found through Xe I emission lines. The most intense features of the luminescence spectra are attributed to atomic N emissions observed above ˜20 eV. Intense N2+ A 2Πu - X2Σ_g+ and B2Σ_u+ - X2Σ_g+ radiance is observed from Xe2+ + N2 collisions. The B state formation cross section decreases with collision energy until 20 eV, after which it becomes independent of impact energy with an approximate value of 3 Å2. The cross section for N2+ A (v > 0) formation increases with energy until 20 eV, after which it remains nearly constant at ˜1 Å2. The N2+ product vibrational distributions extracted from the spectra are non-Franck-Condon for both electronic product states at low collision energies. The distributions resemble a Franck-Condon distribution at the highest energies investigated in this work.

  1. Characterization of molecular beam epitaxy grown β-Nb2N films and AlN/β-Nb2N heterojunctions on 6H-SiC substrates

    NASA Astrophysics Data System (ADS)

    Nepal, Neeraj; Katzer, D. Scott; Meyer, David J.; Downey, Brian P.; Wheeler, Virginia D.; Storm, David F.; Hardy, Matthew T.

    2016-02-01

    β-Nb2N films and AlN/β-Nb2N heterojunctions were grown by molecular beam epitaxy (MBE) on 6H-SiC. The epitaxial nature and β-Nb2N phase were determined by symmetric and asymmetric high-resolution X-ray diffraction (HRXRD) measurements, and were confirmed by grazing incidence diffraction measurements using synchrotron photons. Measured lattice parameters and the in-plane stress of β-Nb2N on 6H-SiC were c = 5.0194 Å, a = 3.0558 Å, and 0.2 GPa, respectively. The HRXRD, transmission electron microscopy, and Raman spectroscopy revealing epitaxial growth of AlN/β-Nb2N heterojunctions have identical orientations with the substrate, abrupt interfaces, and bi-axial stress of 0.88 GPa, respectively. The current finding opens up possibilities for the next generation of high-power devices that cannot be fabricated at present.

  2. 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.

  3. Noncompetitive Gametic Isolation between Sibling Species of Cricket: A Hypothesized Link between Within-Population Incompatibility and Reproductive Isolation between Species

    PubMed Central

    Marshall, Jeremy L.; DiRienzo, Nicholas

    2012-01-01

    Postmating, prezygotic phenotypes are a common mechanism of reproductive isolation. Here, we describe the dynamics of a noncompetitive gametic isolation phenotype (namely, the ability of a male to induce a female to lay eggs) in a group of recently diverged crickets that are primarily isolated from each other by this phenotype. We not only show that heterospecific males are less able to induce females to lay eggs but that there are male by female incompatibilities in this phenotype that occur within populations. We also identify a protein in the female reproductive tract that correlates with the number of eggs that she was induced to lay. Functional genetic tests using RNAi confirm that the function of this protein is linked to egg-laying induction. Moreover, the dysfunction of this protein appears to underlie both within-population incompatibilities and between-species divergence—thus suggesting a common genetic pathway underlies both. However, this is only correlative evidence and further research is needed to assess whether or not the same mutations in the same genes underlie variation at both levels. PMID:23251826

  4. Matrix Isolation and Computational Study of [2C, 2N, x] (X=S, Se) Isomers

    NASA Astrophysics Data System (ADS)

    Voros, Tamas; Tarczay, Gyorgy

    2015-06-01

    The [2C, 2N, S] and the [2C, 2N, Se] systems were investigated by quantum chemical computations and matrix isolation IR spectroscopy. For both systems nine isomers were computationally investigated, for which harmonic and anharmonic vibrational wavenumbers and infrared (IR) intensities were calculated using the CCSD(T)/aug-cc-pVTZ level of theory. The results show that each of the isomers have two or more detectable bands in the mid IR region, which have one or two orders of magnitude larger intensity compared to the IR intensity of the most intense bands of the most stable NCSCN and NCSeCN isomers'. It follows that if the most stable isomers can be detected, then the other previously unobserved isomers generated from NCSCN or NCSeCN should also be detectable with IR spectroscopy. UV spectra were also computed for each isomer at the TD-DFT B3LYP/aug-cc-pVTZ level of theory. These computations showed that the most stable isomers (NCSCN and NCSeCN) can absorb the UV radiation around 250 nm, and the irradiation may promote photoisomerization. This means that if the initial isomers are irradiated by narrow-band UV radiation, new isomers may be generated, which likely decompose by irradiating broad-band UV radiation. The two most stable isomers, sulphur dicyanide (NCSCN) and selenium dicyanide (NCSeCN), were prepared following literature methods. The matrix isolation IR spectra of these molecules in Ar and Kr were measured for the first time. As a result of a selective 254 nm-irradiation of the deposited matrices some new bands appeared in the IR spectra, while the intensity of the bands of NCSCN or NCSeCN were decreased at the same time. Irradiation of the matrices with broad-band UV light decreased the intensity of the bands corresponding to the deposited isomers and some of the bands appeared on the 254 nm-irradiation. On the basis of the analysis of the formation rates of the different bands upon 254 nm photolysis and by comparison with the results of the quantum

  5. 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.

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

    PubMed

    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.

  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.

  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 structural and electronic properties of Ag-adsorbed (SiO2)n (n=1-7) clusters.

    PubMed

    Zhao, Gao-feng; Zhi, Li-li; Guo, Ling-ju; Zeng, Zhi

    2007-12-21

    Equilibrium geometries, charge distributions, stabilities, and electronic properties of the Ag-adsorbed (SiO(2))(n) (n=1-7) clusters have been investigated using density functional theory with generalized gradient approximation for exchange-correlation functional. The results show that the Ag atom preferably binds to silicon atom with dangling bond in nearly a fixed direction, and the incoming Ag atoms tend to cluster on the existing Ag cluster leading to the formation of Ag islands. The adsorbed Ag atom only causes charge redistributions of the atoms near itself. The effect of the adsorbed Ag atom on the bonding natures and structural features of the silica clusters is minor, attributing to the tendency of stability order of Ag(SiO(2))(n) (n=1-7) clusters in consistent with silica clusters. In addition, the energy gaps between the highest occupied and lowest unoccupied molecular orbitals remarkably decrease compared with the pure (SiO(2))(n) (n=1-7) clusters, eventually approaching the near infrared radiation region. This suggests that these small clusters may be an alternative material which has a similar functionality in treating cancer to the large gold-coated silica nanoshells and the small Au(3)(SiO(2))(3) cluster.

  10. 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

  11. 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.

  12. Investigating the Local Physical and Chemical Environments toward the Galactic Center Region - SgrB2(N)

    NASA Astrophysics Data System (ADS)

    Remijan, Anthony; Jones, Paul; Cunningham, Maria; Thorwirth, Sven; Menten, Karl; Schilke, Peter; Belloche, Arnaud; Meier, David; Walsh, Andrew; Kurtz, Stan; Bruenken, Sandra; Mccarthy, Michael C.; Liu, Sheng-Yuan; Pate, Brooks; Corby, Joanna`; Steber, Amanda

    2011-04-01

    The proposed observation will image multiple transitions of four structurally diverse molecules (methanol, formamide, methylamine, and cyanoacetylene) toward the pre-eminent source of molecular emission in the Galaxy, Sgr B2(N). The overall goal is to investigate the local physical and chemical environment of this highly complex region of space. Our hypthesis is that the spatial distributions and localized physical environments of each molecule will help predict the most favorable chemical formation pathways for these species and eventually others. The improved capabilities of the ATCA allow for simultaneous observation of ten 3-cm band transitions of the target molecules using the 64MHz x 32kHz zoom modes of the CABB. This project is an essential extension of the Green Bank Telescope (GBT) PRebiotic Interstellar MOlecular Survey (PRIMOS) toward Sgr B2(N) which has previously been observed across the full 2GHz of the 3-cm band. We will analyze ATCA data from the proposed observation, together with the single dish data from PRIMOS, to obtain a more complete understanding of the compact and extended distributions of these four abundant complex molecules as we work towards the broader goal of determining chemical formation pathways in space.

  13. Thaptomys Thomas 1915 (Rodentia, Sigmodontinae, Akodontini) with karyotypes 2n = 50, FN = 48, and 2n = 52, FN = 52: Two monophyletic lineages recovered by molecular phylogeny

    PubMed Central

    2010-01-01

    A novel karyotype with 2n = 50, FN = 48, was described for specimens of Thaptomys collected at Una, State of Bahia, Brazil, which are morphologically indistinguishable from Thaptomys nigrita, 2n = 52, FN = 52, found in other localities. It was hence proposed that the 2n = 50 karyotype could belong to a distinct species, cryptic of Thaptomys nigrita, once chromosomal rearrangements observed, along with the geographic distance, might represent a reproductive barrier between both forms. Phylogenetic analyses using maximum parsimony and maximum likelihood based on partial cytochrome b sequences with 1077 bp were performed, attempting to establish the relationships among the individuals with distinct karyotypes along the geographic distribution of the genus; the sample comprised 18 karyotyped specimens of Thaptomys, encompassing 15 haplotypes, from eight different localities of the Atlantic Rainforest. The intra-generic relationships corroborated the distinct diploid numbers, once both phylogenetic reconstructions recovered two monophyletic lineages, a northeastern clade grouping the 2n = 50 and a southeastern clade with three subclades, grouping the 2n = 52 karyotype. The sequence divergence observed between their individuals ranged from 1.9% to 3.5%. PMID:21637479

  14. Body-centered superhard BC2N phases from first principles

    NASA Astrophysics Data System (ADS)

    Luo, Xiaoguang; Guo, Xiaoju; Xu, Bo; Wu, Qinghua; Hu, Qianku; Liu, Zhongyuan; He, Julong; Yu, Dongli; Tian, Yongjun; Wang, Hui-Tian

    2007-09-01

    Body-centered BC2N deduced from the unit cell of the recently predicted body-centered carbon [F. J. Ribeiro , Phys. Rev. B 74, 172101 (2006)] are studied with first-principles pseudopotential density functional method. The structural, electronic, and mechanical properties are investigated for 11 possible atomic configurations of body-centered BC2N . Our results show that the sp3 -bonded body-centered BC2N phases have lower density than the previously investigated sp3 -bonded zinc-blende BC2N , wurtzite BC2N , and chalcopyrite BC2N . The struc-A and struc-B composed of the maximum numbers of C-C and B-N bonds have the lowest total energy among the investigated body-centered BC2N structures. Their calculated bulk moduli are 305 and 309GPa , respectively. The theoretical Vickers hardness of the body-centered BC2N is over 60GPa , indicating that it is a potential superhard material with the hardness comparable to cubic boron nitride.

  15. Mild Binding of Protein to C2 N Monolayer Reveals Its Suitable Biocompatibility.

    PubMed

    Li, Baoyu; Li, Weifeng; Perez-Aguilar, Jose Manuel; Zhou, Ruhong

    2017-03-01

    The development of biocompatible nanomaterials for smart drug delivery and bioimaging has attracted great interest in recent years in biomedical fields. Here, the interaction between the recently reported nitrogenated graphene (C2 N) and a prototypical protein (villin headpiece HP35) utilizing atomistic molecular dynamics simulations is studied. The simulations reveal that HP35 can form a stable binding with the C2 N monolayer. Although the C2 N-HP35 attractive interactions are constantly preserved, the binding strength between C2 N and the protein is mild and does not cause significant distortion in the protein's structural integrity. This intrinsic biofriendly property of native C2 N is distinct from several widely studied nanomaterials, such as graphene, carbon nanotubes, and MoS2 , which can induce severe protein denaturation. Interestingly, once the protein is adsorbed onto C2 N surface, its transverse migration is highly restricted at the binding sites. This restriction is orchestrated by C2 N's periodic porous structure with negatively charged "holes," where the basic residues-such as lysine-can form stable interactions, thus functioning as "anchor points" in confining the protein displacement. It is suggested that the mild, immobilized protein attraction and biofriendly aspects of C2 N would make it a prospective candidate in bio- and medical-related applications.

  16. Luminescent nitridophosphates CaP2 N4 :Eu(2+) , SrP2 N4 :Eu(2+) , BaP2 N4 :Eu(2+) , and BaSr2 P6 N12 :Eu(2.).

    PubMed

    Pucher, Florian J; Marchuk, Alexey; Schmidt, Peter J; Wiechert, Detlef; Schnick, Wolfgang

    2015-04-20

    Nitridophosphates MP2 N4 :Eu(2+) (M=Ca, Sr, Ba) and BaSr2 P6 N12 :Eu(2+) have been synthesized at elevated pressures and 1100-1300 °C starting from the corresponding azides and P3 N5 with EuCl2 as dopant. Addition of NH4 Cl as mineralizer allowed for the growth of single crystals. This led to the successful structure elucidation of a highly condensed nitridophosphate from single-crystal X-ray diffraction data (CaP2 N4 :Eu(2+) (P63 , no. 173), a=16.847(2), c=7.8592(16) Å, V=1931.7(6) Å(3) , Z=24, 2033 observed reflections, 176 refined parameters, wR2 =0.096). Upon excitation by UV light, luminescence due to parity-allowed 4f(6) ((7) F)5d(1) →4f(7) ((8) S7/2 ) transition was observed in the orange (CaP2 N4 :Eu(2+) , λmax =575 nm), green (SrP2 N4 :Eu(2+) , λmax =529 nm), and blue regions of the visible spectrum (BaSr2 P6 N12 :Eu(2+) and BaP2 N4 :Eu(2+) , λmax =450 and 460 nm, respectively). Thus, the emission wavelength decreases with increasing ionic radius of the alkaline-earth ions. The corresponding full width at half maximum values (2240-2460 cm(-1) ) are comparable to those of other known Eu(2+) -doped (oxo)nitrides emitting in the same region of the visible spectrum. Following recently described quaternary Ba3 P5 N10 Br:Eu(2+) , this investigation represents the first report on the luminescence of Eu(2+) -doped ternary nitridophosphates. Similarly to nitridosilicates and related oxonitrides, Eu(2+) -doped nitridophosphates may have the potential to be further developed into efficient light-emitting diode phosphors.

  17. The influence of gamete co-incubation length on the in vitro fertility and sex ratio of bovine bulls with different penetration speed.

    PubMed

    Sattar, A; Rubessa, M; Di Francesco, S; Longobardi, V; Di Palo, R; Zicarelli, L; Campanile, G; Gasparrini, B

    2011-12-01

    The objectives of this work were to evaluate whether the sperm penetration speed is correlated to the in vitro fertility and whether adapting the gamete co-incubation length to the kinetics of the bull improves in vitro fertility and affects the sex ratio. In vitro matured oocytes were co-incubated with spermatozoa from four different bulls (A-D). At various post-insemination (p.i.) times (4, 8, 12, 16 and 20 h), samples of oocytes were fixed and stained with DAPI for nuclei examination, while the remaining ones were transferred into culture to evaluate embryo development. The blastocysts produced were sexed by PCR. Two bulls (A and B) had faster kinetics than the others (C and D), as shown by the higher penetration rates recorded at 4 h p.i. (43%, 30%, 11% and 6%, respectively for bulls A, B, C and D; p<0.01). The differences in the kinetics among bulls did not reflect their in vitro fertility. The incidence of polyspermy was higher for faster penetrating bulls (36%, 24%, 16% and 4%, respectively for bulls A, B, C and D; p<0.01) and at longer co-incubation times (0%, 16%, 19%, 30% and 34%, respectively at 4, 8, 12, 16 and 20 h p.i.; p<0.01). The fertilizing ability of individual bulls may be improved by adapting the co-incubation length to their penetration speed. A sperm-oocyte co-incubation length of 8 h ensured the greatest blastocyst yields for the two faster penetrating bulls. On the contrary, 16 h co-incubation was required to increase (p<0.01) cleavage rate of the two slower bulls. Bulls with a faster kinetics did not alter the embryo sex ratio towards males. The female/male (F/M) ratios recorded were 2.1, 1.4, 1.2, 1.3 and 1.6, respectively at 4, 8, 12, 16 and 20 h p.i.

  18. 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

  19. Competing analysis of α and 2p2n-emission from compound nuclei formed in neutron induced reactions

    NASA Astrophysics Data System (ADS)

    Kaur, Amandeep; Sharma, Manoj K.

    2017-01-01

    The decay mechanism of compound system 61Ni* formed in fast neutron induced reactions is explored within the collective clusterization approach of the Dynamical Cluster-decay Model (DCM) in reference to a recent experiment over an energy spread of En = 1- 100 MeV. The excitation functions for the decay of the compound nucleus 61Ni* formed in the n +60Ni reaction show a double humped variation with incident beam energy where the peak at lower energy corresponds to α-emission while the one at higher energy originates from 2 p 2 n-emission. The experimentally observed transmutation of α-emission at lower energy into 2 p 2 n-emission at higher incident energies is explained on the basis of temperature dependence of the binding energies used within the framework of DCM. The cross-sections for the formation of the daughter nucleus 57Fe after emission of α-cluster from the 61Ni* nucleus are addressed by employing the neck length parameter (ΔR), finding decent agreement with the available experimental data. The calculations are done for non-sticking choice of moment of inertia (INS) in the centrifugal potential term, which forms the essential ingredient in DCM based calculations. In addition to this, the effect of mass (and charge) of the compound nucleus is exercised in view of α and 2 p 2 n emission and comparative study of the decay profiles of compound systems with mass A = 17-93 is employed to get better description of decay patterns.

  20. Anderson lattice in the intermediate valence compound Ce3Ni2B2N3-δ

    NASA Astrophysics Data System (ADS)

    Ali, Tahir; Bauer, Ernst; Hilscher, Gerfried; Michor, Herwig

    2011-03-01

    We have studied magnetic, thermodynamic, and transport properties of Ce3Ni2B2N3-δ and its solid solution with the Tc≃13 K superconductor La3Ni2B2N3-δ. The solid solution (La,Ce)3Ni2B2N3-δ reveals a rapid reduction of Tc by increasing the Ce content with a complete suppression of superconductivity at the composition La2.85Ce0.15Ni2B2N3-δ. The low-temperature properties characterize Ce3Ni2B2N3-δ as an intermediate valence system with a moderately enhanced Sommerfeld value γ≃54 mJ/mol K2 and a susceptibility χ0≃1.6×10-3 emu/mol, increased by about one order of magnitude as compared to the respective value χ0≃0.2×10-3 emu/mol of superconducting La3Ni2B2N3-δ (γ=26 mJ/mol K2) which serves as reference with a nonmagnetic rare earth ion. The electrical resistivity and thermoelectric power of Ce3Ni2B2N3-δ are analyzed in terms of the degenerate Anderson lattice model revealing a characteristic Kondo temperature TKALM~1100 K.

  1. $\\frac{{\\rm SO}(2N)}{U(N)}$ 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.

  2. Wear resistance of TiN(Ti2N)/Ti composite layer formed on C17200 alloy by plasma surface Ti-alloying and nitriding

    NASA Astrophysics Data System (ADS)

    Liu, L.; Shen, H. H.; Liu, X. Z.; Guo, Q.; Meng, T. X.; Wang, Z. X.; Yang, H. J.; Liu, X. P.

    2016-12-01

    The duplex treatment of plasma Ti-alloying and plasma nitriding was applied on the surface of C17200 alloy to improve its wear resistance. C17200 substrate was alloyed with Ti using double glow plasma alloying to form a Ti-alloyed layer in its surface, and then treated by plasma nitriding to make a TiN(Ti2N) alloying layer based on the Ti-alloyed surface. The microstructure and formation mechanism were studied by using GDOES, XRD and SEM. The hardness, tribological property and electrical conductivity of C17200 alloy after plasma alloying and nitriding were investigated by mean of micro-hardness tester, friction and wear testers as well as impedance analyzers. Modulus of elasticity and the adhesive strength of TiN(Ti2N)/Ti composite layer were evaluated by nano-indenter and scratch tester. The result shows that a TiN(Ti2N)-Ti-Be-Cu composite layer with a thickness of 27 μm is formed in the C17200 surface and is mainly composed of TiN, Ti2N, Cu(Ti) solid solution, etc. The composite alloying surface consists of the hard TiN(Ti2N)-rich layer on the top surface and Ti-Cu-Be diffusion layer, showing a strong adhesive strength with the C17200 substrate and a little decrease in the modulus of elasticity. A certain amount of Cu and Be together with TiN/Ti2N exists in the outmost, resulting in a better combination of wear resistance and conductive performance.

  3. Thermodynamics of the N2/N3- redox couple in a LiBr-KBr-CsBr melt.

    PubMed

    Kobayashi, Katsutoshi; Nakajima, Hironori; Goto, Takuya; Ito, Yasuhiko

    2005-12-22

    Nitrogen electrode reaction has been investigated in a LiBr-KBr-CsBr melt containing Li3N. The reaction N3- --> 1/2N2 + 3e- is confirmed by quantitative analysis of anodically evolved gas. The Nernst relation holds for the rest potential of Ni electrodes at a nitrogen gas pressure, pN2, of 0.05-1.0 atm and an anion fraction of the N3- ions, xN3-, of 0.003-0.010 (anion fraction). Then, the standard formal potential of the N2/N3- couple, , is evaluated to be 0.251 +/- 0.009 V versus Li+/Li (pN2 = 1 atm, xN3- = 1) at 673 K. The dependence of on the temperature (570-730 K) gives a linear relation, whose slope is (-0.930 +/- 0.117) x 10(-3) V K(-1). Thermodynamic quantities for the formation of Li3N in the melt are also estimated.

  4. Dialkylmethyl-2-(N,N-diisobutyl)acetamidoammonium iodide as a ruthenium selective ligand from nitric acid medium.

    PubMed

    Sharma, Shikha; Ghosh, Sunil K; Sharma, Joti N

    2015-09-15

    A new class of quaternary ammonium iodide based ligands with 2-(N,N-diisobutyl)acetamide as an alkyl appendage have been designed, synthesized and tested for their ability to extract ruthenium selectively from nitric acid medium. The 2-(N,N-diisobutyl)acetamido ammonium iodide with two propyl and a methyl substituents showed best results for the recovery of ruthenium. The optimized concentration of the solvent was found to be 0.2M in 30% isodecyl alcohol/n-dodecane. The stoichiometry of the complex was ascertained by slope analysis method and was found to be 1:1 with respect to ligand L(+)I(-) and Ru(NO)(NO3)3. Ruthenium formed an adduct of structure LRu(NO)(NO3)3 I in the extraction medium. Iodide ion played an important role in the formation of the stable and extractable complex of ruthenium. No extraction was observed when iodide was replaced by nitrate anion in the ligand. The ligand also showed good selectivity for ruthenium in the presence of other metal ions commonly found in nitric acid solutions of nuclear waste.

  5. Control of Meiotic Crossovers: From Double-Strand Break Formation to Designation

    PubMed Central

    Gray, Stephen

    2017-01-01

    Meiosis, the mechanism of creating haploid gametes, is a complex cellular process observed across sexually reproducing organisms. Fundamental to meiosis is the process of homologous recombination, whereby DNA double-strand breaks are introduced into the genome and are subsequently repaired to generate either noncrossovers or crossovers. Although homologous recombination is essential for chromosome pairing during prophase I, the resulting crossovers are critical for maintaining homolog interactions and enabling accurate segregation at the first meiotic division. Thus, the placement, timing, and frequency of crossover formation must be exquisitely controlled. In this review, we discuss the proteins involved in crossover formation, the process of their formation and designation, and the rules governing crossovers, all within the context of the important landmarks of prophase I. We draw together crossover designation data across organisms, analyze their evolutionary divergence, and propose a universal model for crossover regulation. PMID:27648641

  6. 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

  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.

  8. Investigation of Gd3N@C2n (40 <= n <= 44) family by Raman and inelastic electron tunneling spectroscopy

    NASA Astrophysics Data System (ADS)

    Burke, Brian; Chan, Jack; Williams, Keith; Ge, Jiechao; Shu, Chunying; Fu, Wujun; Dorn, Harry; Kushmerick, James; Puretzky, Alexander; Geohegan, David

    2010-03-01

    The structure and vibrational spectrum of Gd3N@C80 is studied through Raman and inelastic electron tunneling spectroscopy (IETS) as well as density functional theory (DFT) and universal force field (UFF) 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 fingerprint 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.

  9. TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2N)

    Atmospheric Science Data Center

    2017-02-27

    ... TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2N) Project Title:  TES Discipline:  Tropospheric ... Earth Science Atmosphere Atmospheric Chemistry/Carbon and Hydrocarbon Compounds Order Data:  ...

  10. Effects of C(2)(n) on a vertically pointing diffraction-limited lidar.

    PubMed

    Schwiesow, R L

    1988-06-15

    Examples of different C(2)(n) profiles lead to substantially different profiles of lidar image radius in a study of the calculated performance of a diffraction-limited lidar system. The differences in image radii indicate the usefulness of a ground-based lidar for measurement of C(2)(n) profiles used to predict optical propagation phenomena. We conclude that the overall strength of the C(2)(n) profile and its general altitude dependence can be determined from inspection of the image radius profile. Approximate calculations of available and required SNRs show that a lidar with a telescope aperture of 0.5 m and a few pulses of ~1-J total transmitted energy will provide useful image radius data to an altitude of 20 km under daytime conditions. The weighting function for sensitivity of the fractional increase in image radius to changes of C(2)(n) on a logarithmic altitude scale is approximately constant with height.

  11. Close Resemblance Between Local Summer Insolation, O2/N2 and Total Air Content from the Dome Fuji Ice Core, Antarctica

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Nakazawa, T.; Aoki, S.; Fujii, Y.; Watanabe, O.; Severinghaus, J. P.

    2004-12-01

    O2/N2 ratio from ice cores has shown depleted values compared to the atmosphere due to selective exclusion of O2 during bubble formation at the base of firn. The long record from the Vostok ice core revealed that O2/N2 ratio records the local summer insolation. Insolation may affect physical properties of the firn near the surface, which later determines how much O2/N2 is fractionated the during bubble close-off process. We present here a supportive record of O2/N2 ratio for the last 340 kyr along the Dome Fuji ice core, Antarctica, which shows variations similar to the summer insolation at 77° S. Moreover, the variation of total air content (TAC) in the Dome Fuji core resembles that of O2/N2. High TAC and high O2/N2 ratio appear at times of low summer insolation. Since the TAC variation is too large to be explained by the elevation change at the Dome Fuji site in the past, a possible cause is variation of the so-called ``lock-in zone'' thickness on the orders of several meters. The lock-in zone is a region 0-10 m thick at the bottom of firn where horizontal impermeable layers prevent vertical gas mixing. At times of low insolation, the firn would retain inhomogeneities such as wind crusts and high-density layers. These small-scale inhomogeneities do not affect bulk density very much but may help trap the gases at a lower bulk density (and higher porosity and thus TAC) through formation of a thicker lock-in zone than in times of high insolation. High insolation would homogenize the firn structure through recrystallization. O2/N2 ratio would be less depleted if there is a lock-in zone within the total close-off zone, because O2 molecules once excluded from bubbles would eventually be re-trapped in the ice in the lock-in zone.

  12. 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.

  13. Adaptation of pandemic H2N2 influenza A viruses in humans.

    PubMed

    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; Bahl, Justin; Smith, Gavin J D

    2015-02-01

    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.

  14. Thermodynamics of the Si-O-N system. 2: Stability of Si{sub 2}N{sub 2}O(s) by high-temperature mass spectrometric vaporization

    SciTech Connect

    Rocabois, P.; Chatillon, C.; Bernard, C.

    1996-05-01

    The Si{sub 2}N{sub 2}O(s) compound is vaporized in a multiple Knudsen-cell connected to a mass spectrometer. Comparison of SiO(g) and N{sub 2}(g) pressures between different samples in the Si-N-O system, as triphasic or diphasic mixtures from Si(s), Si{sub 3}N{sub 4}(s), and Si{sub 2}N{sub 2}O(s), allows the determination of the SiO(g) evaporation coefficient and consequently the calculation of the equilibrium pressure of SiO(g). Then the standard enthalpy of formation of Si{sub 2}N{sub 2}O(s) is determined: {Delta}{sub f}H{sub m}{degree}(Si{sub 2}N{sub 2}O, s, 298.15K) = {minus}887.5 {+-} 10 kJ{center_dot}mol{sup {minus}1}.

  15. 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.

  16. 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.

  17. Studies on three-dimensional coordination polymer [Cd2(N2H4)2(N3)4]n: crystal structure, thermal decomposition mechanism and explosive properties.

    PubMed

    Liu, Zhenhua; Zhang, Tonglai; Zhang, Jianguo; Wang, Shaozong

    2008-06-15

    A 3D coordination polymer of cadmium(II) hydrazine azide, [Cd2(N2H4)2(N3)4]n, was synthesized and characterized by elemental analysis and Fourier transform infrared (FT-IR) spectrum. Its crystal structure was determined by single crystal X-ray diffraction analysis. The crystal belongs to monoclinic, P2(1)/c space group, a=12.555(2)A, b=11.724(2)A, c=7.842(1)A, beta=94.56(2) degrees and Z=4. The crystal contains two crystallographically independent sets of distorted octahedral Cd(II) atoms and dimeric units of Cd2N2, Cd2(NNN)2, Cd2(NN)2 through double micro-1, 1 azide bridges, micro-1, 3 azide bridges and bidentate bridging hydrazine ligands, respectively, and thus generating a 3D network structure. The thermal decomposition mechanism of the complex was studied by using differential scanning calorimetry (DSC), thermogravimetry-derivative thermogravimetry (TG-DTG) and FT-IR techniques. Under nitrogen atmosphere with a heating rate of 10 degrees C/min, the thermal decomposition of the complex contained two intense exothermic decomposition processes in the range of 150-304 degrees C in the DSC curve, and the final decomposed residue at 500 degrees C was Cd. Sensitivity tests revealed that the title complex is very insensitive to external stimuli.

  18. A recurrent loss-of-function alanyl-tRNA synthetase (AARS) mutation in patients with Charcot-Marie-Tooth disease type 2N (CMT2N).

    PubMed

    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

    2012-01-01

    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.

  19. Surrogate Measurements of Actinide (n,2n) Cross Sections with NeutronSTARS

    SciTech Connect

    Casperson, R. J.; Burke, J. T.; Hughes, R. O.; Akindele, O. A.; Koglin, J. D.; Wang, B.; Tamashiro, A.

    2016-09-27

    Directly measuring (n,2n) cross sections on short-lived actinides presents a number of experimental challenges. The surrogate reaction technique is an experimental method for measuring cross sections on short-­lived isotopes, and it provides a unique solution for measuring (n,2n) cross sections. This technique involves measuring a charged-­particle reaction cross section, where the reaction populates the same compound nucleus as the reaction of interest. To perform these surrogate (n,2n) cross section measurements, a silicon telescope array has been placed along a beam line at the Texas A&M University Cyclotron Institute, which is surrounded by a large tank of gadolinium-doped liquid scintillator, which acts as a neutron detector. The combination of the charge-particle and neutron-detector arrays is referred to as NeutronSTARS. In the analysis procedure for calculating the (n,2n) cross section, the neutron detection efficiency and time structure plays an important role. Due to the lack of availability of isotropic, mono-energetic neutron sources, modeling is an important component in establishing this efficiency and time structure. This report describes the NeutronSTARS array, which was designed and commissioned during this project. It also describes the surrogate reaction technique, specifically referencing a 235U(n,2n) commissioning measurement that was fielded during the past year. Advanced multiplicity analysis techniques have been developed for this work, which should allow for efficient analysis of 241Pu(n,2n) and 239Pu(n,2n) cross section measurements

  20. 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

  1. 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).

  2. Effect of Si3N4 powder reactivity on the preparation of the Si2N2O-Al2O3 silicon aluminum oxynitride solid solution

    NASA Technical Reports Server (NTRS)

    Sekercioglu, I.; Wills, R. R.

    1979-01-01

    Dense high-purity silicon aluminum oxynitride was prepared by reactive hot-pressing of an Si3N4-Al2O3-SiO2 mixture. The formation of a single-phase material was found to be critically dependent on the Si3N4 powder in the starting mixture. It is suggested that evolution of a chlorine- and nitrogen-containing species may enhance the reactivity of Si3N4 in this reaction. Densities of O prime sialons are very similar to that of Si2N2O, the widely quoted value in the ceramics literature of 3.1 g/cu cm for the density of Si2N2O being incorrect.

  3. 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

  4. Microwave transitions from pairs of Rb n d5 /2n d5 /2 atoms

    NASA Astrophysics Data System (ADS)

    Lee, Jeonghun; Gallagher, T. F.

    2016-06-01

    We have observed resonant microwave transitions between pairs of atoms. Specifically, we have observed the processes n d5 /2n d5 /2→(n +1 ) dj(n -2 ) f7 /2 and n d5 /2n d5 /2→(n +2 ) p3 /2(n -1 ) d5 /2 for 35 ≤n ≤44 . These transitions are allowed due to the dipole-dipole-induced configuration interaction between the n d5 /2n d5 /2 state and the energetically nearby (n +2 ) p3 /2(n -2 ) f7 /2 state, which admixes some of the latter into the former. The resulting microwave transitions are analogous to two-photon transitions in which one of the photons has been replaced by the dipole-dipole interaction. We have developed a configuration interaction description of the transitions, which gives a good description of the interaction over the range 35 ≤n ≤42 . Over this range of n the detuning varies from 0.095 to 1.482 GHz, the microwave frequencies vary from 26.970 to 45.916 GHz, and the requisite microwave powers vary by a factor of over 1000.

  5. Lusztig symmetries and Poincare-Birkhoff-Witt basis for wUr,sd(osp(1|2n))

    NASA Astrophysics Data System (ADS)

    Liu, Junli; Yang, Shilin

    2013-12-01

    We investigate a new kind of two-parameter weak quantized superalgebra {wU}_{r, s}d(osp(1|2n)), which is a weak Hopf superalgebra. It has a homomorphic image which is isomorphic to the usual two-parameter quantum superalgebra {U}_{r,s}({osp}(1|2n)) of {osp}(1|2n). We also discuss the basis of {wU}_{r, s}d(osp(1|2n)) by Lusztig's symmetries.

  6. Density functional calculations for a high energy density compound of formula C6H 6-n (NO 2) n.

    PubMed

    Chi, Wei-Jie; Li, Lu-Lin; Li, Bu-Tong; Wu, Hai-Shun

    2012-08-01

    A series of polynitroprismanes, C(6)H(6-n )(NO(2))(n) (n = 1-6) intended for use as high energy density compounds (HEDCs) were designed computationally. Their electronic structures, heats of formation, interactions between nitro groups, specific enthalpies of combustion, bond dissociation energies, and explosive performances (detonation velocities and detonation pressures) were calculated using density functional theory (DFT) with the 6-311 G** basis set. The results showed that all of the polynitroprismanes had high positive heats of formation that increased with the number of substitutions for the prismane derivatives, while the specific enthalpy of combustion decreased as the number of nitro groups increased. In addition, the range of enthalpy of combustion reducing is getting smaller. Interactions between ortho (vicinal) groups deviate from the group additivity rule and decrease as the number of nitro groups increases. In terms of thermodynamic stability, all of the polynitroprismanes had higher bond dissociation energies (BDEs) than RDX and HMX. Detonation velocities and detonation pressures were estimated using modified Kamlet-Jacobs equations based on the heat of detonation (Q) and the theoretical density of the molecule (ρ). It was found that ρ, D, and P are strongly linearly related to the number of nitro groups. Taking both their energetic properties and thermal stabilities into account, pentanitroprismane and hexanitroprismane are potential candidate HEDCs.

  7. Development of Polysulfone (PSF)-Carbon Molecular Sieve (CMS) Mixed Matrix Membrane (MMM) For O2/N2 Gas Separation

    NASA Astrophysics Data System (ADS)

    Ismail, A. F.; Rahman, W. R.; Aziz, F.

    2009-06-01

    Mixed matrix membranes (MMMs) comprising polysulfone (PSF) Udel® P-1700 and synthesized carbon molecular sieve (CMS) particles (<25 μm) have been fabricated and characterized. CMS were synthesized by using polyacrylonitrile (PAN) as polymer precursor. The casting process was performed at the processing temperature close to Tg of PSF in order to maintain the flexibility of polymer during film formation. This study investigated the effects of CMS loadings (10, 20, 30 and 35 wt%) on the morphology and the gas separation performance of PSF-CMS MMMs. The fabricated MMMs were characterized using TGA, DSC, FESEM and single gas permeation test using high purity O2 and N2. Based on FESEM micrograph, a good polymer-sieve adhesion was achieved in MMMs using the combination of PSF-CMS even at high sieve loading (up to 35 wt%). The formation of `sieve-in-the-cage' morphology in PSF-CMS MMMs has been minimized to a great extend by implementing casting procedure at the operating temperature close to the Tg of polymer matrix. The O2 and N2 permeability for MMMs were increased with increasing CMS loading; while at 20 wt% CMS loading the O2/N2 selectivity attain the highest value which is 5.97 with the O2 permeability of 7.9617 barrers.

  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. Megagametophyte organization in diploid alfalfa meiotic mutants producing 4n pollen and 2n eggs.

    PubMed

    Calderini, O; Mariani, A

    1995-01-01

    Megagametogenesis was studied in five diploid alfalfa mutants producing 4n pollen and 2n eggs, using a stain-clearing technique. All mutants produced embryo sacs with a variable number of supernumerary nuclei both at the early (bi- and tetra-nucleate) and at the late (eight-nucleate) stages of development. The presence of supernumerary nuclei is considered to be a consequence of the production of coenocytic megaspores. The production of 2n eggs was confirmed through cytological investigation by means of the diameter of the egg-cell nucleolus. The frequency of 2n eggs was lower than the frequency of binucleated macrospores as previously determined. This discrepancy may be due to environmental effects but also to the fact that binucleated macrospores may degenerate or may, after two mitotic divisions, give rise to eight-nucleated embryo sacs counted as normals.

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. Risk assessment of H2N2 influenza viruses from the avian reservoir.

    PubMed

    Jones, Jeremy C; Baranovich, Tatiana; Marathe, Bindumadhav M; Danner, Angela F; Seiler, Jon P; Franks, John; Govorkova, Elena A; Krauss, Scott; Webster, Robert G

    2014-01-01

    H2N2 influenza A viruses were the cause of the 1957-1958 pandemic. Historical evidence demonstrates they arose from avian virus ancestors, and while the H2N2 subtype has disappeared from humans, it persists in wild and domestic birds. Reemergence of H2N2 in humans is a significant threat due to the absence of humoral immunity in individuals under the age of 50. Thus, examination of these viruses, particularly those from the avian reservoir, must be addressed through surveillance, characterization, and antiviral testing. The data presented here are a risk assessment of 22 avian H2N2 viruses isolated from wild and domestic birds over 6 decades. Our data show that they have a low rate of genetic and antigenic evolution and remained similar to isolates circulating near the time of the pandemic. Most isolates replicated in mice and human bronchial epithelial cells, but replication in swine tissues was low or absent. Multiple isolates replicated in ferrets, and 3 viruses were transmitted to direct-contact cage mates. Markers of mammalian adaptation in hemagglutinin (HA) and PB2 proteins were absent from all isolates, and they retained a preference for avian-like α2,3-linked sialic acid receptors. Most isolates remained antigenically similar to pandemic A/Singapore/1/57 (H2N2) virus, suggesting they could be controlled by the pandemic vaccine candidate. All viruses were susceptible to neuraminidase inhibitors and adamantanes. Nonetheless, the sustained pathogenicity of avian H2N2 viruses in multiple mammalian models elevates their risk potential for human infections and stresses the need for continual surveillance as a component of prepandemic planning.

  15. 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

  16. Measurements of d2n and A1n: Probing the neutron spin structure

    DOE PAGES

    Flay, D.; Posik, M.; Parno, D. S.; ...

    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

  17. OsSDS is essential for DSB formation in rice meiosis.

    PubMed

    Wu, Zhigang; Ji, Jianhui; Tang, Ding; Wang, Hongjun; Shen, Yi; Shi, Wenqing; Li, Yafei; Tan, Xuelin; Cheng, Zhukuan; Luo, Qiong

    2015-01-01

    SDS is a meiosis specific cyclin-like protein and required for DMC1 mediated double-strand break (DSB) repairing in Arabidopsis. Here, we found its rice homolog, OsSDS, is essential for meiotic DSB formation. The Ossds mutant is normal in vegetative growth but both male and female gametes are inviable. The Ossds meiocytes exhibit severe defects in homologous pairing and synapsis. No γH2AX immunosignals in Ossds meiocytes together with the suppression of chromosome fragmentation in Ossds-1 Osrad51c, both provide strong evidences that OsSDS is essential for meiotic DSB formation. Immunostaining investigations revealed that meiotic chromosome axes are normally formed but both SC installation and localization of recombination elements are failed in Ossds. We suspected that this cyclin protein has been differentiated pretty much between monocots and dicots on its function in meiosis.

  18. An infrared investigation of the (CO2)n- clusters: core ion switching from both the ion and solvent perspectives.

    PubMed

    Shin, J-W; Hammer, N I; Johnson, M A; Schneider, H; Glöss, A; Weber, J M

    2005-04-14

    The (CO2)n- clusters are thought to accommodate the excess electron by forming a localized molecular anion, or "core ion", solvated by the remaining, largely neutral CO2 molecules. Earlier studies interpreted discontinuities in the (CO2)n- photoelectron spectra to indicate that both the CO2- and C2O4- species were present in a size-dependent fashion. Here we use vibrational predissociation spectroscopy to unambiguously establish the molecular structures of the core ions in the 2 < or = n < or = 17 size range. Spectra are reported in the 2300-3800 cm(-1) region, which allows us to independently monitor the contribution of each ion through its characteristic overtone and combination bands. These signature bands are observed to be essentially intact in the larger clusters, establishing that the CO2- and C2O4- molecular ions are indeed the only electron accommodation modes at play. The size dependence of the core ion suggested in earlier analyses of the photoelectron spectra is largely confirmed, although both species are present over a range of clusters near the expected critical cluster sizes, as opposed to the prompt changes inferred earlier. Perturbations in the bands associated with the nominally neutral CO2 "solvent" molecules are correlated with the changes in the molecular structure of the core ion. These observations are discussed in the context of a diabatic model for electron delocalization over the CO2 dimer. In this picture, the driving force leading to the transient formation of the monomer ion is traced to the solvent asymmetry inherent in an incomplete coordination shell.

  19. Monoclinic and triclinic concomitant polymorphs of di-mu-pyridazine-1kappa(2)N:2kappa(2)N'-bis[(saccharinato)silver(I)].

    PubMed

    Hamamci, Sevim; Yilmaz, Veysel T; Büyükgüngör, Orhan

    2006-01-01

    Crystallization of the title compound, di-mu-pyridazine-1kappa(2)N:2kappa(2)N'-bis[(2,3-dihydro-3-oxobenzisosulfonazolato-kappaN)silver(I)], [Ag2(C7H4NO3S)2(C4H4N2)2], from acetonitrile yields both monoclinic, (I), and triclinic, (II), polymorphs. In both forms, the silver(I) ions have a slightly distorted trigonal AgN(3) coordination geometry and are doubly bridged by two neutral pyridazine (pydz) ligands, generating a centrosymmetric dimeric structure. The saccharinate (sac) ligands are N-coordinated. The dihedral angles between the sac and pydz rings are 8.43 (7) and 7.94 (8) degrees in (I) and (II), respectively, suggesting that the dimeric molecule is nearly flat. The bond geometry is similar in both polymorphs. In (I), the dimers interact with each other via aromatic pi(sac)-pi(pydz) stacking interactions, forming two-dimensional layers, which are further crosslinked by weak C-H...O interactions. Compound (II) exhibits similar C-H...O and pi-pi interactions, but additional C-H...pi and pi...Ag interactions help to stabilize the packing of the dimers.

  20. Efficient blue organic light-emitting diodes using N(2) ,N(2) ,N(11) ,N(11) ,5,6,7,8-octaphenyltriphenylene-2,11-diamine derivatives.

    PubMed

    Kim, Young Seok; Jeong, Su Jin; Lee, Hyun Woo; Kim, Jwajin; Lee, Song Eun; Kim, Young Kwan; Yoon, Seung Soo

    2016-06-01

    In this study, we have synthesized phenyl-substituted triphenylene derivatives, using the Diels-Alder reaction and the Buchwald-Hartwig reaction. To investigate electroluminescence properties of these materials, multilayer organic light-emitting diode (OLED) devices were fabricated with a structure of indium-tin-oxide (ITO) (180 nm)/4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPB) (50 nm)/blue-emitting materials (1-3) (30 nm)/bathophenanthroline (Bphen) (35 nm)/lithium quinolate (Liq) (2 nm)/Al (100 nm). A device using N(2) ,N(2) ,N(11) ,N(11) ,5,6,7-heptaphenyltriphenylene-2,11-diamine (2) exhibited efficient blue emission with luminous, power, and external quantum efficiencies of 0.92 cd/A, 0.67 lm/W, and 1.17% at 20 mA/cm(2) , respectively. The Commission International de L'Éclairage coordinates of this device were (x = 0.15, y = 0.09) at 6.0 V. Copyright © 2015 John Wiley & Sons, Ltd.

  1. 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.

  2. Novel Concentrated Li[(FSO2)(n-C4F9SO2)N]-Based Ether Electrolyte for Superior Stability of Metallic Lithium Anode.

    PubMed

    Fang, Zheng; Ma, Qiang; Liu, Pin; Ma, Jie; Hu, Yong-Sheng; Zhou, Zhibin; Li, Hong; Huang, Xuejie; Chen, Liquan

    2017-02-08

    Lithium (fluorosulfonyl)(n-nonafluorobutanesulfonyl)imide [Li[(FSO2)(n-C4F9SO2)N] (LiFNFSI)] is investigated as a conducting salt, which can form a relatively stable solid-electrolyte-interphase film in concentrated ether electrolyte to achieve favorable protection for lithium metal anodes. Li|Cu and Li|Li cells with concentrated LiFNFSI-based electrolyte have been demonstrated to display high average Coulombic efficiency (≈97%) and excellent cycling stability (over 1,000 h) of metallic lithium anodes, compared to concentrated lithium bis(trifluoromethanesulfonyl)imide [Li[N(SO2CF3)2] (LiTFSI)]-based electrolyte. The morphologies and compositions of the lithium-metal anode surface are also comparatively analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Moreover, superior electrochemical performance in the concentrated LiFNFSI-based electrolyte for Li|LiFePO4 cells is also presented herein. These results indicate that concentrated LiFNFSI-based electrolyte is a promising candidate for metallic lithium rechargeable batteries.

  3. [2n2π + 2n2π] cycloadditions: an alternative to forbidden [4π + 4π] processes. The case of nitrone dimerization.

    PubMed

    Roca-López, David; Tejero, Tomás; Caramella, Pierluigi; Merino, Pedro

    2014-01-21

    A theoretical study based on (U)M06-2X/cc-pVTZ calculations has been used to investigate the [3 + 3] thermal dimerization of nitrones to 1,4,2,5-dioxadiazinanes in both the gas phase and in dichloromethane solution. Calculations suggest that dimerization of nitrones takes place through a concerted mechanism involving a formal disallowed [4π + 4π] cycloaddition with a free energy barrier of 30.8 kcal mol(-1). The corresponding diradical and zwitterionic stepwise mechanisms have also been studied, but the located transition structures are kinetically disfavoured. An alternative mechanism through a five-membered ring intermediate formed by a classical [3 + 2] dipolar cycloaddition can also be discarded. The five-membered ring intermediate is unstable to cycloreversion and its isomerization to the final dioxadiazinane involves a high free energy barrier (68.6 kcal mol(-1)). Calculations also show that the dimerization process is slower in dichloromethane than in the gas phase owing to the larger polarity of nitrones and that inclusion of diffuse functions at the studied level does not modify the observed results. The apparently disfavoured [3 + 3] dimerization of nitrones can actually be explained as a bispseudopericyclic [2n2π + 2n2π] process in which the favourable FO interactions between the nitrone oxygen and the C=N π* bypass the WH-forbidden process.

  4. 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.

  5. Effects of copper vapour on thermophysical properties of CO2-N2 plasma

    NASA Astrophysics Data System (ADS)

    Zhong, Linlin; Wang, Xiaohua; Rong, Mingzhe; Cressault, Yann

    2016-10-01

    CO2-N2 mixtures are often used as arc quenching medium (to replace SF6) in circuit breakers and shielding gas in arc welding. In such applications, copper vapour resulting from electrode surfaces can modify characteristics of plasmas. This paper therefore presents an investigation of the effects of copper on thermophysical properties of CO2-N2 plasma. The equilibrium compositions, thermodynamic properties (including mass density, specific enthalpy, and specific heat), transport coefficients (including electrical conductivity, viscosity, and thermal conductivity), and four kinds of combined diffusion coefficients due to composition gradients, applied electric fields, temperature gradients, and pressure gradients respectively, were calculated and discussed for CO2-N2 (mixing ratio 7:3) plasma contaminated by different proportions of copper vapour. The significant influences of copper were observed on all the properties of CO2-N2-Cu mixtures. The better ionization ability and larger molar mass of copper and larger collision integrals related to copper, should be responsible for such influences.

  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. First on-sky results of the CO-SLIDAR C(2)(n) profiler.

    PubMed

    Voyez, Juliette; Robert, Clélia; Conan, Jean-Marc; Mugnier, Laurent M; Samain, Etienne; Ziad, Aziz

    2014-05-05

    COupled SLope and scIntillation Detection And Ranging (CO-SLIDAR) is a recent profiling method of the vertical distribution of atmospheric turbulence strength (C(2)(n) profile). It takes advantage of correlations of slopes and of scintillation, both measured with a Shack-Hartmann wavefront sensor on a binary star. In this paper, we present the improved CO-SLIDAR reconstruction method of the C(2)(n) profile and the first on-sky results of the CO-SLIDAR profiler. We examine CO-SLIDAR latest performance in simulation, taking into account the detection noise bias and estimating error bars along with the turbulence profile. The estimated C(2)(n) profiles demonstrate the accuracy of the CO-SLIDAR method, showing sensitivity to both low and high altitude turbulent layers. CO-SLIDAR is tested on-sky for the first time, on the 1.5 m MeO (Métrologie Optique) telescope at Observatoire de la Côte d'Azur (France). The reconstructed profiles are compared to turbulence profiles estimated from meteorological data and a good agreement is found. We discuss CO-SLIDAR's contribution in the C(2)(n) profilers' landscape and we propose some improvements of the instrument.

  8. Synthesis of phase-pure U2N3 microspheres and its decomposition into UN

    DOE PAGES

    Silva, Chinthaka M.; Hunt, Rodney Dale; Snead, Lance Lewis; ...

    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

  9. 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.

  10. Reaction Mechanism of the Symmetry-Forbidden [2+2] Addition of Ethylene and Acetylene to Amido-Substituted Digermynes and Distannynes Ph2N-EE-NPh2, (E = Ge, Sn): A Theoretical Study.

    PubMed

    Zhao, Lili; Jones, Cameron; Frenking, Gernot

    2015-08-24

    Quantum chemical calculations of reaction mechanisms for the formal [2+2] addition of ethylene and acetylene to the amido-substituted digermyne and distannyne Ph2N-EE-NPh2 (E = Ge, Sn) have been carried out by using density functional theory at the BP86/def2-TZVPP level. The nature and bonding situations were studied with the NBO method and with the charge and energy decomposition analysis EDA-NOCV. The addition of ethylene to Ph2N-EE-NPh2 takes place through an initial [2+1] addition to one metal atom and consecutive rearrangement to four-membered cyclic species, which feature a weak E-E bond. Rotation about the C-C bond with concomitant rupture of the E-E bond leads to the 1,2-disubstituted ethanes, which have terminal E(NPh2) groups. The overall reaction Ph2N-EE-NPh2+C2H4→(Ph2N)E-C2H4-E(NPh2) has very low activation barriers and is slightly exergonic for E = Ge but slightly endergonic for E = Sn. The analysis of the electronic structure shows that there is charge donation of nearly one electron to the ethylene moiety already in the first part of the reaction. The energy partitioning analysis suggests that the HOMO(Ph2N-EE-NPh2)→LUMO(C2H4) interaction has a similar strength as the HOMO(C2H4)→LUMO(Ph2N-EE-NPh2) interaction. The [2+2] addition of acetylene to Ph2N-EE-NPh2 also takes place through an initial [2+1] approach, which eventually leads to 1,2-disubstituted olefins (Ph2N)E-C2H2-E(NPh2). The formation of the energetically lowest lying conformations of cis-(Ph2N)E-C2H2-E(NPh2), which occurs with very low activation barriers, is clearly exergonic for the germanium and the tin compound. The trans-coordinated isomers of (Ph2N)E-C2H2-E(NPh2) are slightly lower in energy than the cis form but they are separated by a substantial energy barrier for the rotation about the C-C bond. The energy decomposition analysis indicates that the initial reaction takes place under formation of electron-sharing bonds between triplet fragments rather than HOMO

  11. Xenon-nitrogen chemistry: gas-phase generation and theoretical investigation of the xenon-difluoronitrenium ion F2N-Xe+.

    PubMed

    Operti, Lorenza; Rabezzana, Roberto; Turco, Francesca; Borocci, Stefano; Giordani, Maria; Grandinetti, Felice

    2011-09-12

    The xenon-difluoronitrenium ion F(2)N-Xe(+) , a novel xenon-nitrogen species, was obtained in the gas phase by the nucleophilic displacement of HF from protonated NF(3) by Xe. According to Møller-Plesset (MP2) and CCSD(T) theoretical calculations, the enthalpy and Gibbs energy changes (ΔH and ΔG) of this process are predicted to be -3 kcal mol(-1) . The conceivable alternative formation of the inserted isomers FN-XeF(+) is instead endothermic by approximately 40-60 kcal mol(-1) and is not attainable under the employed ion-trap mass spectrometric conditions. F(2)N-Xe(+) is theoretically characterized as a weak electrostatic complex between NF(2)(+) and Xe, with a Xe-N bond length of 2.4-2.5 Å, and a dissociation enthalpy and free energy into its constituting fragments of 15 and 8 kcal mol(-1), respectively. F(2)N-Xe(+) is more fragile than the xenon-nitrenium ions (FO(2)S)(2)NXe(+), F(5)SN(H)Xe(+), and F(5)TeN(H)Xe(+) observed in the condensed phase, but it is still stable enough to be observed in the gas phase. Other otherwise elusive xenon-nitrogen species could be obtained under these experimental conditions.

  12. WAVE2, N-WASP, and Mena facilitate cell invasion via phosphatidylinositol 3-kinase-dependent local accumulation of actin filaments.

    PubMed

    Takahashi, Kazuhide; Suzuki, Katsuo

    2011-11-01

    Cell migration is accomplished by the formation of cellular protrusions such as lamellipodia and filopodia. These protrusions result from actin filament (F-actin) rearrangement at the cell cortex by WASP/WAVE family proteins and Drosophila enabled (Ena)/vasodilator-stimulated factor proteins. However, the role of each of these actin cytoskeletal regulatory proteins in the regulation of three-dimensional cell invasion remains to be clarified. We found that platelet-derived growth factor (PDGF) induces invasion of MDA-MB-231 human breast cancer cells through invasion chamber membrane pores. This invasion was accompanied by intensive F-actin accumulation at the sites of cell infiltration. After PDGF stimulation, WAVE2, N-WASP, and a mammalian Ena (Mena) colocalized with F-actin at the sites of cell infiltration in a phosphatidylinositol 3-kinase (PI3K)-dependent manner. Depletion of WAVE2, N-WASP, or Mena by RNA interference (RNAi) abrogated both cell invasion and intensive F-actin accumulation at the invasion site. These results indicate that by mediating intensive F-actin accumulation at the sites of cell infiltration, WAVE2, N-WASP, and Mena are crucial for PI3K-dependent cell invasion induced by PDGF.

  13. 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

  14. Galaxy formation

    SciTech Connect

    Silk, J.

    1984-11-01

    Implications of the isotropy of the cosmic microwave background on large and small angular scales for galaxy formation are reviewed. In primeval adiabatic fluctuations, a universe dominated by cold, weakly interacting nonbaryonic matter, e.g., the massive photino is postulated. A possible signature of photino annihilation in our galactic halo involves production of cosmic ray antiprotons. If the density is near its closure value, it is necessary to invoke a biasing mechanism for suppressing galaxy formation throughout most of the universe in order to reconcile the dark matter density with the lower astronomical determinations of the mean cosmological density. A mechanism utilizing the onset of primordial massive star formation to strip gaseous protogalaxies is described. Only the densest, early collapsing systems form luminous galaxies. (ESA)

  15. 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).

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2N)

    Atmospheric Science Data Center

    2017-02-27

    TES/Aura L2 Carbon Dioxide (CO2) Nadir (TL2CO2N) News:  TES News ... Level:  L2 Platform:  TES/Aura L2 Carbon Dioxide Spatial Coverage:  5.2 x 8.5 km nadir ... Data: TES Order Tool Parameters:  Carbon Dioxide Order Data:  Search and Order:   Earthdata ...

  1. Nqrs Data for C24H22Cl2Cu2N6 (Subst. No. 1582)

    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 C24H22Cl2Cu2N6 (Subst. No. 1582)

  2. Solvent-Induced Reductive Activation in Gas Phase [Bi(CO2)n]- Clusters

    NASA Astrophysics Data System (ADS)

    Thompson, Michael C.; Ramsay, Jacob Sondergaard; Weber, J. Mathias

    2016-06-01

    We report infrared photodissociation spectra of [Bi(CO2)n]- (n=2-9) cluster anions. We determine the charge carrier geometry by comparing calculated vibrational frequencies based on density functional theory to the experimental spectra. The vibrational frequencies and the charge carrier geometry depend strongly on the solvation environment present in the cluster. We discuss the interaction of bismuth and CO_2 in the presence of an excess electron in the context of heterogeneous catalytic reduction of CO_2.

  3. Structures and Solvation Effects of [Fe(CO_2)n]- Cluster Anions

    NASA Astrophysics Data System (ADS)

    Thompson, Michael C.; Weber, J. Mathias

    2016-06-01

    We present infrared photodissociation spectra of [Fe(CO_2)n]- (n=3-7) cluster anions. We use density functional theory to compare calculated vibrational frequencies to our experimental spectra to determine plausible structures for the molecular charge carriers. The spectra display similar characteristics to those of other complexes of first-row transition metals with CO_2 ligands, and show signatures of several structural motifs.

  4. Efficient High-Energy Pulse-Train Generation Using a 2 n-Pulse Michelson Interferometer.

    PubMed

    Siders, C W; Siders, J L; Taylor, A J; Park, S G; Weiner, A M

    1998-08-01

    We demonstrate a novel, Michelson-based, ultrafast multiplexer with a throughput approaching 100% for a polarization-multiplexed train and 50% for a linearly polarized train, which is compatible with a high-energy pulse train and shaped-pulse generation. The interpulse spacings in the resultant 2(n)-pulse train can be adjusted continuously from multinanoseconds through zero. Using this interferometer, we also demonstrate generation of a 16-pulse train of terahertz pulses.

  5. Kinetics Studies of Radical-Radical Reactions: The NO2 + N2H3 System

    DTIC Science & Technology

    2013-10-01

    investigating the kinetics of this elementary reaction . 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES...Viewgraph 3. DATES COVERED (From - To) September 2013- October 2013 4. TITLE AND SUBTITLE Kinetics Studies of Radical-Radical Reactions (I): The NO2...characteristics in relevant operating environments. Here we report theoretical results obtained on the prototypical radical- radical reaction : NO2 + N2H3

  6. Kinetics Studies of Radical-Radical Reactions (I): The NO2 + N2H3 System

    DTIC Science & Technology

    2013-08-01

    the potential energy surface for the NO2 + N2H3 system and have established the most likely reaction mechanism. The technique of laser photolysis...configuration interactions and coupled-cluster theories with single and double excitations, and correction for triple excitations. Specifically, the...differentially pumped chamber containing an electron impact ionization quadrupole mass spectrometer. 4. Results and Discussion To our knowledge

  7. Nqrs Data for C9H30Br7Cd2N3 (Subst. No. 1200)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' 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 C9H30Br7Cd2N3 (Subst. No. 1200)

  8. 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)

  9. 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.

  10. 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.

  11. Slit2N Inhibits Transmission of HIV-1 from Dendritic Cells to T-cells by Modulating Novel Cytoskeletal Elements

    PubMed Central

    Shrivastava, Ashutosh; Prasad, Anil; Kuzontkoski, Paula M.; Yu, Jinlong; Groopman, Jerome E.

    2015-01-01

    Dendritic cells are among the first cells to encounter sexually acquired human immunodeficiency virus (HIV-1), in the mucosa, and they can transmit HIV-1 to CD4+ T-cells via an infectious synapse. Recent studies reveal that actin-rich membrane extensions establish direct contact between cells at this synapse and facilitate virus transmission. Genesis of these contacts involves signaling through c-Src and Cdc42, which modulate actin polymerization and filopodia formation via the Arp2/3 complex and Diaphanous 2 (Diaph2). We found that Slit2N, a ligand for the Roundabout (Robo) receptors, blocked HIV-1-induced signaling through Arp2/3 and Diaph2, decreased filopodial extensions on dendritic cells, and inhibited cell-to-cell transmission of HIV-1 in a Robo1-dependent manner. Employing proteomic analysis, we identified Flightless-1 as a novel, Robo1-interacting protein. Treatment with shRNAs reduced levels of Flightless-1 and demonstrated its role in efficient cell-to-cell transfer of HIV-1. These results suggest a novel strategy to limit viral infection in the host by targeting the Slit/Robo pathway with modulation of cytoskeletal elements previously unrecognized in HIV-1 transmission. PMID:26582347

  12. a Look at Nitrile Chemistry in SGR B2(N) Using the Combined Power of the GBT and the VLA

    NASA Astrophysics Data System (ADS)

    Steber, Amanda; Zaleski, Daniel P.; Seifert, Nathan A.; Neill, Justin; Muckle, Matt; Pate, Brooks; Corby, Joanna F.; Remijan, Anthony

    2014-06-01

    Nitriles form the most prolific family of molecules known in the ISM, and laboratory work shows that radical-driven chemistry can account for the formation of a diverse set of nitrile and imine molecules. Broadband reaction screening of nitrile chemistry in a pulsed discharge nozzle coupled to a chirped-pulse Fourier transform rotational spectrometer has enabled detections of several new interstellar species including E- and Z-ethanimine and E-cyanomethanimine. The detections were made by direct comparisons of laboratory broadband rotational spectra with the Robert C. Byrd Green Bank Telescope (GBT) PRebiotic Interstellar MOlecule Survery (PRIMOS) survey towards Sgr B2(N), the most chemically complex interstellar region known. In order to probe nitrile chemistry in Sgr B2, we targeted low energy rotational transitions in the 18-21 GHz range of several nitriles with the Karl G. Jansky Very Large Array (VLA) at ˜1 arcsecond resolution. The data indicate that most nitriles and nitrile derivatives are co-spatial with shell shaped continuum features thought to be expanding ionization fronts. The CH2CN radical and imine species in particular are NOT associated with the hot core known as the "Large Molecule Heimat", where most large organic molecules are thought to reside. This result suggests radical driven nitrile chemistry may be promoted by near-UV radiation in moderate density regions of molecular clouds, and the data will be useful for evaluating possible formation mechanisms. R.A. Loomis et al. Ap. J. L., 765, (L9), 2013. D.P. Zaleski et al. Ap. J. L., 765, (L10), 2013.

  13. 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.

  14. Neoadjuvant Chemoradiation Therapy Is Beneficial for Clinical Stage T2 N0 Esophageal Cancer Patients Due to Inaccurate Preoperative Staging

    PubMed Central

    Zhang, Jennifer Q.; Hooker, Craig M.; Brock, Malcolm V.; Shin, James; Lee, Sue; How, Remealle; Franco, Noreli; Prevas, Helen; Hulbert, Alicia; Yang, Stephen C.

    2014-01-01

    Background It remains unclear if patients with clinical stage T2 N0 (cT2 N0) esophageal cancer should be offered induction therapy vs surgical intervention alone. Methods This was a retrospective cohort study of cT2 N0 patients undergoing induction therapy, followed by surgical resection, or resection alone, at the Johns Hopkins Hospital from 1989 to 2009. Kaplan-Meier analysis was used to compare all-cause mortality in cT2 N0 patients who had resection alone vs those who had induction chemoradiation therapy, followed by resection. Results A study cohort of 69 patients was identified and divided into two groups: 55 patients (79.7%) received induction therapy and 14 (20.3%) did not. No statistically significant difference in 5-year survival rate was observed for the two groups: 49.5% for the resection-only group and 53.8% for the induction group. More than 50% of cT2 N0 patients were understaged. Conclusions For cT2 N0 esophageal cancer patients, the benefit of neoadjuvant therapy is still unclear. Induction therapy for cT2 N0 did not translate into a statistically significant improvement in survival. However, due to the significant understaging of T2 N0 patients, we recommend neoadjuvant therapy to all cT2N0 patients before operation. PMID:22269708

  15. Novel measurements of refractive index, density and mid-infrared integrated band strengths for solid O2, N2O and NO2 : N2O4 mixtures

    NASA Astrophysics Data System (ADS)

    Fulvio, D.; Sivaraman, B.; Baratta, G. A.; Palumbo, M. E.; Mason, N. J.

    2009-06-01

    We present novel measurements of the refractive index, density and integrated band strengths of mid-infrared features of solid N2O at 16 K and of NO2 and N2O4 in two frozen NO2:N2O4 mixtures deposited at 16 and 60 K. The refractive index and density measurements were performed also for frozen O2 deposited at 16 K. In this case, the integrated band strength values could not be determined since O2 is a homonuclear molecule and therefore its fundamental mode is not infrared active. The solid samples were analysed by infrared spectroscopy in the 8000.800 cm -1 range. The sample thickness was measured by the interference curve obtained using a He-Ne laser operating at 543 nm. The refractive index at this laser wavelength was obtained, by numerical methods, from the measured amplitude of the interference curve. The density values were obtained using the Lorentz-Lorenz relation. Integrated band strength values were then obtained by a linear fit of the integrated band intensities plotted versus column density values. The astrophysical relevance of these novel measurements is briefly discussed.

  16. Cloud Formation

    NASA Astrophysics Data System (ADS)

    Graham, Mark Talmage

    2004-05-01

    Cloud formation is crucial to the heritage of modern physics, and there is a rich literature on this important topic. In 1927, Charles T.R. Wilson was awarded the Nobel Prize in physics for applications of the cloud chamber.2 Wilson was inspired to study cloud formation after working at a meteorological observatory on top of the highest mountain in Scotland, Ben Nevis, and testified near the end of his life, "The whole of my scientific work undoubtedly developed from the experiments I was led to make by what I saw during my fortnight on Ben Nevis in September 1894."3 To form clouds, Wilson used the sudden expansion of humid air.4 Any structure the cloud may have is spoiled by turbulence in the sudden expansion, but in 1912 Wilson got ion tracks to show up by using strobe photography of the chamber immediately upon expansion.5 In the interim, Millikan's study in 1909 of the formation of cloud droplets around individual ions was the first in which the electron charge was isolated. This study led to his famous oil drop experiment.6 To Millikan, as to Wilson, meteorology and physics were professionally indistinct. With his meteorological physics expertise, in WWI Millikan commanded perhaps the first meteorological observation and forecasting team essential to military operation in history.7 But even during peacetime meteorology is so much of a concern to everyone that a regular news segment is dedicated to it. Weather is the universal conversation topic, and life on land could not exist as we know it without clouds. One wonders then, why cloud formation is never covered in physics texts.

  17. Study of the 27Al(n,2n)26Al reaction and its potential for ion-temperature measurements (abstract)

    NASA Astrophysics Data System (ADS)

    Wallner, A.; Chuvaev, S. V.; Filatenkov, A. A.; Ikeda, Y.; Kutschera, W.; Vonach, H.

    2001-01-01

    A detailed measurement of the 27Al(n,2n)26Al reaction cross sections was performed in the near-threshold region (Eth=13.54 MeV), and its possible applicability for ion temperature measurements was investigated. The production of the long-lived radionuclide 26Al (t1/2=7.2×105 a) is of considerable interest to the fusion reactor program. Particularly long-lived radionuclides may lead to a significant long-term waste-disposal. Al-containing materials and Si carbide are candidate materials for fusion-reactor systems. The Al(n,2n) reaction and the two step process 28Si(n,np+d)27Al(n,2n) are the dominating processes for the formation of 26Al in a fusion reactor.1 The 27Al(n,2n)26Al reaction is expected to vary strongly with neutron energy above threshold. An accurate description of the excitation function is necessary to estimate the production of 26Al in a typical D-T fusion environment. From the existing data on cross sections it was not possible to produce an unambiguous excitation function. We started therefore a project to determine this excitation function more accurately. It has been pointed out by Smither and Greenwood2 that the 27Al(n,2n)26Al reaction can be used as a monitor to determine the ion temperature in a D-T fusion plasma. This method makes use of the neutron energy distribution as a sensitive function of the plasma ion temperature. The temperature sensitivity is most pronounced if the excitation function is strongly nonlinear and if the threshold falls within the energy region of the emitted neutrons: For the 27Al(n,2n)26Al reaction the threshold lies at 13.54 MeV and the (n,2n) reaction is expected to a strongly varying function of the neutron energy near threshold. Al samples were irradiated with 14 MeV neutrons generated via the T(d,n)4He reaction at three different laboratories under different conditions. The produced 26Al was measured using the extremely sensitive method of accelerator mass spectrometry (AMS). 26Al/27Al isotope ratios as low as

  18. 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.

  19. 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

  20. Vapochromic behavior of {Ag2(Et2O)2[Au(C6F5)2]2}n with volatile organic compounds.

    PubMed

    Fernández, Eduardo J; López-de-Luzuriaga, José M; Monge, Miguel; Olmos, M Elena; Puelles, Raquel C; Laguna, Antonio; Mohamed, Ahmed A; Fackler, John P

    2008-09-15

    The vapochromic behaviors of {Ag2L2[Au(C6F5)2]2}n (L = Et2O (1), Me2CO (2), THF (3), CH3CN (4)) were studied. {Ag2L2[Au(C6F5)2]2}n (L = Et2O (1)) was synthesized by the reaction of [Bu4N][Au(C6F5)2] with AgOClO3 in 1:1 molar ratio in CH2Cl2/Et2O (1:2). 1 was used as starting material with THF to form {Ag2L2[Au(C6F5)2]2}n (L = THF (3)). 3 crystallizes in the monoclinic space group C2/c and consists of tetranuclear units linked together via aurophilic contacts resulting in the formation of a 1D polymer that runs parallel to the crystallographic z axis. The gold(I) atoms are linearly coordinated to two pentafluorophenyl groups and display additional Au...Ag close contacts within the tetranuclear units with distances of 2.7582(3) and 2.7709(3) A. Each silver(I) center is bonded to the two oxygen atoms of the THF molecules with a Ag-O bond distance of 2.307(3) A. TGA analysis showed that 1 loses two molecules of the coordinated solvent per molecular unit (1st one: 75-100 degrees, second one: 150-175 degrees C), whereas 2, 3, and 4 lose both volatile organic compounds (VOCs) and fluorinated ligands in a less well defined manner. Each complex loses both the fluorinated ligands and the VOCs by a temperature of about 325 degrees C to give a 1:1 gold/silver product. X-ray powder diffraction studies confirm that the reaction of vapors of VOCs with 1 in the solid state produce complete substitution of the ether molecules by the new VOC. The VOCs are replaced in the order CH3CN > Me2CO > THF > Et2O, with the ether being the easiest to replace. {Ag2(Et2O)2[Au(C6F5)2]2}n and {Ag2(THF)2[Au(C6F5)2]2} n both luminesce at room temperature and at 77 K in the solid state. Emission maxima are independent of the excitation wavelength used below about 500 nm. Emission maxima are obtained at 585 nm (ether) and 544 nm (THF) at room temperature and at 605 nm (ether) and 567 nm (THF) at 77 K.

  1. Vibrational frequency shifts of H2, N2 and O2 adsorbed in NaA zeolite.

    NASA Astrophysics Data System (ADS)

    Koubi, Laure; Blain, Monique; Cohen De Lara, Evelyne; Leclercq, Jean-Marie

    1995-04-01

    We report ab initio calculations on H2,N2 and O2 and on the same molecules in interaction with a Na+ cation. The results are compared to experimental data on induced infrared band of H2, N2 and O2 adsorbed in NaA zeolite. (AIP)

  2. Overexpression and characterization of the chromosomal aminoglycoside 2'-N-acetyltransferase of Providencia stuartii.

    PubMed

    Franklin, K; Clarke, A J

    2001-08-01

    The gene coding for aminoglycoside 2'-N-acetyltransferase Ia [AAC(2')-Ia] from Providencia stuartii was amplified by PCR and cloned. The resulting construct, pACKF2, was transferred into Escherichia coli for overexpression of AAC(2')-Ia as a fusion protein with an N-terminal hexa-His tag. The fusion protein was isolated and purified by affinity chromatography on Ni(2+)-nitrilotriacetic acid agarose and gel permeation chromatography on Superdex 75. Comparison of the specific activity of this enzyme with that of its enterokinase-digested derivative lacking the His tag indicated that the presence of the extra N-terminal peptide does not affect activity. The temperature and pH optima for activity of both forms of the 2'-N-acetyltransferase were 20 degrees C and pH 6.0, respectively, while the enzymes were most stable at 15 degrees C and pH 8.1. The Michaelis-Menten kinetic parameters for AAC(2')-Ia at 20 degrees C and pH 6.0 were determined using a series of aminoglycoside antibiotics possessing a 2'-amino group and a concentration of acetyl coenzyme A fixed at 10 times its K(m) value of 8.75 microM. Under these conditions, gentamicin was determined to be the best substrate for the enzyme in terms of both K(m) and k(cat)/K(m) values, whereas neomycin was the poorest. Comparison of the kinetic parameters obtained with the different aminoglycosides indicated that their hexopyranosyl residues provided the most important binding sites for AAC(2')-Ia activity, while the enzyme exhibits greater tolerance further from these sites. No correlation was found between these kinetic parameters and MICs determined for P. stuartii PR50 expressing the 2'-N-acetyltransferase, suggesting that its true in vivo function is not as a resistance factor.

  3. Fate of tetraploid cells in 4n<-->2n chimeric mouse blastocysts.

    PubMed

    Mackay, Gillian E; West, John D

    2005-12-01

    Previous studies have shown that tetraploid (4n) cells rarely contribute to the derivatives of the epiblast lineage of mid-gestation 4n<-->2n mouse chimeras. The aim of the present study was to determine when and how 4n cells were excluded from the epiblast lineage of such chimeras. The contributions of GFP-positive cells to different tissues of 4n<-->2n chimeric blastocysts labelled with tauGFP were analysed at E3.5 and E4.5 using confocal microscopy. More advanced E5.5 and E7.5 chimeric blastocysts were analysed after a period of diapause to allow further growth without implantation. Tetraploid cells were not initially excluded from the epiblast in 4n<-->2n chimeric blastocysts and they contributed to all four blastocyst tissues at all of the blastocyst stages examined. Four steps affected the allocation and fate of 4n cells in chimeras, resulting in their exclusion from the epiblast lineage by mid-gestation. (1) Fewer 4n cells were allocated to the inner cell mass than trophectoderm. (2) The blastocyst cavity tended to form among the 4n cells, causing more 4n cells to be allocated to the hypoblast and mural trophectoderm than the epiblast and polar trophectoderm, respectively. (3) 4n cells were depleted from the hypoblast and mural trophectoderm, where initially they were relatively enriched. (4) After implantation 4n cells must be lost preferentially from the epiblast lineage. Relevance of these results to the aetiology of human confined placental mosaicism and possible implications for the interpretation of mouse tetraploid complementation studies of the site of gene action are discussed.

  4. Thin films of TiO2:N for photo-electrochemical applications.

    PubMed

    Trenczek-Zajac, A; Pamula, E; Radecka, M; Kowalski, K; Reszka, A; Brudnik, A; Kusior, E; Zakrzewska, K

    2012-06-01

    Dc-pulsed magnetron sputtering from Ti target in reactive Ar+O2+N2 atmosphere was used to grow stoichiometric TiO2:N and non-stoichiometric TiO2-x:N thin films. X-ray diffraction at glancing incidence, atomic force microscopy AFM, scanning electron microscopy SEM, X-ray photoelectron spectroscopy XPS, and optical spectrophotometry were applied for sample characterization. Measurements of photocurrent versus voltage and wavelength over the ultraviolet uv and visible vis ranges of the light spectrum were performed in order to assess the performance of nitrogen-doped titanium dioxide thin films as photoanodes for hydrogen generation in photoelectrochemical cells, PEC. Undoped TiO2 and TiO2-x films were found to be composed of anatase and rutile mixture with larger anatase crystallites (25-35 nm) while the growth of smaller rutile crystallites (6-10 nm) predominated at higher nitrogen flow rates etaN2 as measured in standard cubic centimeters, sccm. Nitrogen-to-titanium ratio increased from N/Ti = 0.05 at etaN2 = 0.8 sccm for stoichiometric TiO2:N to N/Ti = 0.11 at etaN2 = 0.8 sccm for nonstoichiometric TiO2-x:N thin films. A red-shift in the optical absorbance was observed with an increase in etaN2. Doping with nitrogen improved photoelectrochemical properties over the visible range of the light spectrum in the case of nonstoichiometric samples.

  5. 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

  6. 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.

  7. 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.

  8. C4H2, HC3N and C2N2 in Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Kunde, V. G.; Aikin, A. C.; Hanel, R. A.; Jennings, D. E.; Maguire, W. C.; Samuelson, R. E.

    1981-08-01

    Voyager 1 took IR measurements of the atmosphere of Titan, and obtained an average of 346 spectra, mostly from the center of the disk. The compounds C4H2, HC3N, and C2N2 were detected in the atmosphere of Titan. The identification of two compounds containing nitrogen, in addition to HCN, provides further evidence for the abundance of free N2 on Titan. The organic compounds observed in the atmosphere of Titan are summarized in a table, which also indicates the approximate mole fraction for each compound identified previously. The observed compounds originate by reactions of methane and nitrogen radicals in a predominantly nitrogen atmosphere.

  9. Vibrational spectra of (BaF2)n (n=1-6) clusters

    NASA Astrophysics Data System (ADS)

    Pandey, Ratnesh K.; Waters, Kevin; Nigam, Sandeep; Pandey, Ravindra; Pandey, Avinash C.

    2016-05-01

    The vibrational properties of alkaline-earth metal fluoride clusters (BaF2)n (n=1-6) are investigated in the framework of density functional theory. The calculated Raman and Infrared (IR) spectra reveals shift in Raman and IR peak position towards lower frequency region with the increase in the cluster size. Further the calculated spectra have been compared with the experimental vibrational spectra of bulk BaF2 crystal. Even though the smaller size cluster lacks translational symmetry, the structural and vibrational characteristic of (BaF2)5-6 are nearer to bulk counterpart.

  10. Bitwise Bell-inequality violations for an entangled state involving 2N ions

    SciTech Connect

    Pope, D.T.; Milburn, G.J.

    2004-05-01

    Following on from previous work [J.-A ring . Larsson, Phys. Rev. A 67, 022108 (2003)], Bell inequalities based on correlations between binary digits are considered for a particular entangled state involving 2N trapped ions. These inequalities involve applying displacement operations to half of the ions and then measuring correlations between pairs of corresponding bits in the binary representations of the number of center-of-mass phonons of N particular ions. It is shown that the state violates the inequalities and thus displays nonclassical correlations. It is also demonstrated that it violates a Bell inequality when the displacements are replaced by squeezing operations.

  11. Transport mechanisms in SnO2(N+)/SiO(x)/Si(n) solar cells

    NASA Astrophysics Data System (ADS)

    Chambouleyron, I.; Marques, F. C.

    This paper refers to the transport mechanisms in SnO2(n+)/SiO(x)/Si(n) solar cells. I vs V curves at dark and under varying illumination conditions were measured in the temperature range 296-372 K. Three transport mechanisms, occurring at different biases, that dominate the electrical behavior of the cells, are identified. At low forward bias the dominant mechanism is thermoionic field emission. At intermediate bias recombination mechanism predominates. Finally at high forward biases the dominant mechanism is diffusion.

  12. Development of a Standard Maritime C2N Profile Using Satellite Measurements

    DTIC Science & Technology

    2015-03-01

    considered. Similar laser and optics applications can also benefit from the findings of this research. Because over 70% of the earth is covered by water it...this value is typically set to 27 m/s. The Hufnagel model is only valid above the first strong inversion layer - the region near the ground where heat...model. At approx- imately 1 km, surface effects become negligible and turbulence decreases with height at a slower rate. The first inversion in C2n occurs

  13. 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.

  14. 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.

  15. 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.

  16. Planet Formation

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Fonda, Mark (Technical Monitor)

    2002-01-01

    Modern theories of star and planet formation and of the orbital stability of planetary systems are described and used to discuss possible characteristics of undiscovered planetary systems. The most detailed models of planetary growth are based upon observations of planets and smaller bodies within our own Solar System and of young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth as do terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed, and the methods that are being used and planned for detecting and characterizing extrasolar planets are reviewed.

  17. 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.

  18. Gas phase vibrational spectroscopy of cold (TiO2)n(-) (n = 3-8) clusters.

    PubMed

    Weichman, Marissa L; Song, Xiaowei; Fagiani, Matias R; Debnath, Sreekanta; Gewinner, Sandy; Schöllkopf, Wieland; Neumark, Daniel M; Asmis, Knut R

    2016-03-28

    We report infrared photodissociation (IRPD) spectra for the D2-tagged titanium oxide cluster anions (TiO2)n(-) with n = 3-8 in the spectral region from 450 to 1200 cm(-1). The IRPD spectra are interpreted with the aid of harmonic spectra from BP86/6-311+G* density functional theory calculations of energetically low-lying isomers. We conclusively assign the IRPD spectra of the n = 3 and n = 6 clusters to global minimum energy structures with Cs and C2 symmetry, respectively. The vibrational spectra of the n = 4 and n = 7 clusters can be attributed to contributions of at most two low-lying structures. While our calculations indicate that the n = 5 and n = 8 clusters have many more low-lying isomers than the other clusters, the dominant contributions to their spectra can be assigned to the lowest energy structures. Through comparison between the calculated and experimental spectra, we can draw conclusions about the size-dependent evolution of the properties of (TiO2)n(-) clusters, and on their potential utility as model systems for catalysis on a bulk TiO2 surface.

  19. SH Observations In and Toward Sgr B2(N): Linking the Missing Sulfur

    NASA Astrophysics Data System (ADS)

    McCarthy, Michael

    Where is the missing sulfur in the molecular reservoir of the interstellar medium (ISM)? In the warm gas phase ISM, the abundance of sulfur is nearly equivalent to its solar value, but in the cold, diffuse clouds which span the space between stars, sulfur is depleted by several orders of magnitude. Our inability to account for this depletion represents a significant gap in our understanding of the fundamental chemical and physical processes occurring in the primordial reservoirs of gas and dust in the ISM. Central to this chemistry is SH, a radical for which few observations presently exist, and for which SOFIA is uniquely capable of accessing in its ground rotational state. We propose observations of SH in the cold, shocked molecular shell surrounding Sgr B2(N), and, simultaneously, in diffuse and translucent clouds along the line of sight to Sgr B2(N). We will constrain the abundance of SH, and compare it to previous measurements of SO, CS, C_2S, HCS(+) , H_2CS, and H_2S in these sources which span the evolutionary timescale from diffuse clouds to dense, cold shocked regions.

  20. Q2 dependence of the neutron spin structure function g2(n) at low Q2.

    PubMed

    Kramer, K; Armstrong, D S; Averett, T D; Bertozzi, W; Binet, S; Butuceanu, C; Camsonne, A; Cates, G D; Chen, J-P; Choi, Seonho; Chudakov, E; Cusanno, F; Deur, A; Djawotho, P; Dutta, D; Finn, J M; Gao, H; Garibaldi, F; Gayou, O; Gilman, R; Glamazdin, A; Gorbenko, V; Griffioen, K A; Hansen, J-O; Higinbotham, D W; Hinton, W; Horn, T; de Jager, C W; Jiang, X; Korsch, W; LeRose, J; Lhuillier, D; Liyanage, N; Margaziotis, D J; McCormick, K; Meziani, Z-E; Michaels, R; Milbrath, B; Moffit, B; Nanda, S; Perdrisat, C F; Pomatsalyuk, R; Punjabi, V; Reitz, B; Roche, J; Roché, R; Roedelbronn, M; Savvinov, N; Secrest, J; Singh, J; Sirca, S; Slifer, K; Solvignon, P; Steiner, D J; Suleiman, R; Sulkosky, V; Tobias, A; Vacheret, A; Xiao, Y; Zheng, X; Zhou, J; Zhu, L; Zhu, X; Zołnierczuk, P A

    2005-09-30

    We present the first measurement of the Q2 dependence of the neutron spin structure function g2(n) at five kinematic points covering 0.57 (GeV/c)2 < or = Q2 < or = 1.34 (GeV/c)2 at x approximately = 0.2. Though the naive quark-parton model predicts g2 = 0, nonzero values occur in more realistic models of the nucleon which include quark-gluon correlations, finite quark masses, or orbital angular momentum. When scattering from a noninteracting quark, g2(n) can be predicted using next-to-leading order fits to world data for g1(n). Deviations from this prediction provide an opportunity to examine QCD dynamics in nucleon structure. Our results show a positive deviation from this prediction at lower Q2, indicating that contributions such as quark-gluon interactions may be important. Precision data obtained for g1(n) are consistent with next-to-leading order fits to world data.

  1. 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

  2. Millimeter Wave Spectrum and Astronomical Search for Vinyl Formate

    NASA Astrophysics Data System (ADS)

    Alonso, E. R.; Kolesniková, L.; Tercero, B.; Cabezas, C.; Alonso, J. L.; Cernicharo, J.; Guillemin, J.-C.

    2016-11-01

    Previous detections of methyl and ethyl formate make other small substituted formates potential candidates for observation in the interstellar medium. Among them, vinyl formate is one of the simplest unsaturated carboxylic ester. The aim of this work is to provide direct experimental frequencies of the ground vibrational state of vinyl formate in a large spectral range for astrophysical use. The room-temperature rotational spectrum of vinyl formate has been measured from 80 to 360 GHz and analyzed in terms of Watson’s semirigid rotor Hamiltonian. Two thousand six hundred transitions within J = 3-88 and K a = 0-28 were assigned to the most stable conformer of vinyl formate and a new set of spectroscopic constants was accurately determined. Spectral features of vinyl formate were then searched for in Orion KL, Sgr B2(N), B1-b, and TMC-1 molecular clouds. Upper limits to the column density of vinyl formate are provided.

  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. Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

    NASA Astrophysics Data System (ADS)

    Sode, M.; Jacob, W.; Schwarz-Selinger, T.; Kersten, H.

    2015-02-01

    A comprehensive experimental investigation of absolute ion and neutral species densities in an inductively coupled H2-N2-Ar plasma was carried out. Additionally, the radical and ion densities were calculated using a zero-dimensional rate equation model. The H2-N2-Ar plasma was studied at a pressure of 1.5 Pa and an rf power of 200 W. The N2 partial pressure fraction was varied between fN2=0 % and 56% by a simultaneous reduction of the H2 partial pressure fraction. The Ar partial pressure fraction was held constant at about 1%. NH3 was found to be produced almost exclusively on the surfaces of the chamber wall. NH3 contributes up to 12% to the background gas. To calculate the radical densities with the rate equation model, it is necessary to know the corresponding wall loss times twrad of the radicals. twrad was determined by the temporal decay of radical densities in the afterglow with ionization threshold mass spectrometry during pulsed operation and based on these experimental data the absolute densities of the radical species were calculated and compared to measurement results. Ion densities were determined using a plasma monitor (mass and energy resolved mass spectrometer). H3+ is the dominant ion in the range of 0.0 ≤fN2<3.4 % . For 3.4 2-N2-Ar plasma reasonably well. The ion chemistry, i.e., the production and loss processes of the ions and radicals, is discussed in detail. The main features, i.e., the qualitative abundance of the ion species and the ion density dependence on the N2 partial pressure fraction, are well

  6. 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.

  7. (Tl[Au(C(6)Cl(5))(2)])(n): A vapochromic complex.

    PubMed

    Fernández, Eduardo J; López-De-Luzuriaga, José M; Monge, Miguel; Olmos, M Elena; Pérez, Javier; Laguna, Antonio; Mohamed, Ahmed A; Fackler, John P

    2003-02-26

    The X-ray structure of (Tl[Au(C(6)Cl(5))(2)])(n), 1, consists of 1-D linear polymer chains parallel to the crystallographic z axis. The crystal structure of 1 has channels that run parallel to these chains with interatom distances in the range 3.231-4.076 A. There are holes in these channels with diameters as large as 10.471 A, which can accommodate a variety of solvents. Complex 1 displays reversible vapochromic emission and absorption spectral behavior when the solid is exposed to a variety of organic vapors such as acetone, acetonitrile, triethylamine, acetylacetone, tetrahydrothiophene, 2-fluoropyridine, tetrahydrofuran, and pyridine. Complex 1 is luminescent at room temperature and at 77 K in the solid state. UV excitation at 495 nm leads to an emission at 531 nm.

  8. t-C8B2N2: A potential superhard material

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Shi, Rui; Gan, Li-Hua

    2017-02-01

    A potential superhard material C8B2N2 with I-4m2 space group is found and confirmed to be stable with first-principles calculations. The results show that its structure is highly incompressible with bulk modulus of 383.4 GPa and shear modulus of 383.0 GPa. It shows that this material is nearly isotropy with universal anisotropy index of 0.056, and its fractional anisotropy ratio of shear modulus and bulk modulus are 0.0055 and 0.0, respectively. Interestingly, its theoretical bulk modulus, shear modules, Young's modulus, Poisson's ratio and Vickers hardness are almost same to those of well-known superhard material c-BN.

  9. [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.

  10. Crystal structure of catena-poly[silver(I)-μ-l-valinato-κ2 N:O

    PubMed Central

    Takagi, Yoshitaka; Okamoto, Youhei; Inoue, Chisato; Kasuga, Noriko Chikaraishi

    2017-01-01

    The reaction of Ag2O with l-valine (l-Hval, C5H11NO2) in a 1:2 molar ratio in water, followed by vapour diffusion, afforded a coordination polymer of the title compound, [Ag(C5H10NO2)]n, with N—Ag—O repeat units, which is classified as a type III silver(I) complex with amino acid ligands. The asymmetric unit consists of two independent units of [Ag(l-val)]. In the crystal, the polymeric chains run along [101], and neighbouring chains are linked via a weak Ag⋯Ag inter­action and N—H⋯O hydrogen bonds. The title complex exhibited anti­microbial activity against selected bacteria (Escherichia coli, Bacillus subtilis, Staphylococcous aureus and Psedomonas aeruginosa). PMID:28316807

  11. Density functional and ab initio investigation of S2N2 and (SN)2

    NASA Astrophysics Data System (ADS)

    Moon, Jiwon; Chae, Myoungju; Kim, Joonghan

    2017-03-01

    Quantum chemical calculations were performed to calculate the molecular properties of the 1Ag state of disulfur dinitride, S2N2, and the 1A1 state of the SN dimer, (SN)2, using density functional theory (DFT) and ab initio methods. The molecular structure of (SN)2 is a trapezoid instead of a rectangle. Because the multireference character of (SN)2 is considerable, most hybrid DFTs poorly describe its molecular properties. In contrast, old generalized gradient approximations give qualitatively correct descriptions of the molecular properties of (SN)2. Multi-state second-order multiconfigurational perturbation theory gives results that are close to those from multireference configuration interaction with the Davidson correction. The multireference character should be considered when calculating the molecular properties of poly sulfur nitride systems.

  12. Structure of Co(H2)n + Clusters, for n = 1-6

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Maitre, Philippe

    1995-01-01

    The geometries and H2 binding energies have been determined for Co(H2)n (sup +), for n = 1-6. The binding energies are in good agreement with experiment. The shape of the clusters is used to explain the pairwise decrease in the binding energies. The bonding in CoH2 (sup +) and Co(H2)2 (sup +) is very similar and is enhanced by sd (sigma) hybridization. The next two H2 molecules add to the side of Co(H2)2 (sup +). These two additional H2 molecules cannot benefit from sd (sigma) hybridization and are less strongly bound. The addition of the fifth and sixth H2 molecules eliminates sd (sigma) hybridization as a mechanism for reducing Co-H2 repulsion. This coupled with the smaller Co to H2 (sigma *) donation results in another decrease in the binding energies.

  13. 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.

  14. Ab initio study on (CO2)n clusters via electrostatics- and molecular tailoring-based algorithm

    NASA Astrophysics Data System (ADS)

    Jovan Jose, K. V.; Gadre, Shridhar R.

    An algorithm based on molecular electrostatic potential (MESP) and molecular tailoring approach (MTA) for building energetically favorable molecular clusters is presented. This algorithm is tested on prototype (CO2)n clusters with n = 13, 20, and 25 to explore their structure, energetics, and properties. The most stable clusters in this series are seen to show more number of triangular motifs. Many-body energy decomposition analysis performed on the most stable clusters reveals that the 2-body is the major contributor (>96%) to the total interaction energy. Vibrational frequencies and molecular electrostatic potentials are also evaluated for these large clusters through MTA. The MTA-based MESPs of these clusters show a remarkably good agreement with the corresponding actual ones. The most intense MTA-based normal mode frequencies are in fair agreement with the actual ones for smaller clusters. These calculated asymmetric stretching frequencies are blue-shifted with reference to the CO2 monomer.

  15. Electronic and magnetic properties of bare armchair BC2N nanoribbons

    NASA Astrophysics Data System (ADS)

    Li, Hong; Xiao, Xiang; Tie, Jun; Lu, Jing

    2017-03-01

    We present the electronic and magnetic properties of bare armchair BC2N nanoribbons (ABC2NNRs) in the view of density functional calculations. We consider three types of edge terminations with a width of 0.75 2.10 nm. All the investigated ribbons exhibit magnetic ground states with the magnetic moments mainly located on the edge C atoms. Room temperature accessible magnetic stabilities are obtained for ABC2NNRs with NC-NC and NC-BC edge alignments. We find the ABC2NNRs have various electronic structures, where half-metal, metal, and semiconductor are all acquired depend on the edge alignment and magnetic coupling state. The results show the ABC2NNRs can be a promising candidate material in nanoelectronics and nanospintronics.

  16. 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.

  17. 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.

  18. Greatly facilitated oxygen vacancy formation in ceria nanocrystallites.

    PubMed

    Migani, Annapaola; Vayssilov, Georgi N; Bromley, Stefan T; Illas, Francesc; Neyman, Konstantin M

    2010-08-28

    The formation of oxygen vacancies in nanoparticles Ce(n)O(2n) (n < or = 80), studied using density-functional calculations, is found to be greatly facilitated compared to extended surfaces, which explains the observed spectacular reactivity of nanostructured ceria.

  19. A comparative study of three-terminal Hanle signals in CoFe/SiO{sub 2}/n{sup +}-Si and Cu/SiO{sub 2}/n{sup +}-Si tunnel junctions

    SciTech Connect

    Lee, Jeong-Hyeon; Cho, B. K.; He, Shumin; Grünberg, Peter; Jin, Mi-Jin; Yoo, Jung-Woo

    2016-01-18

    We performed three-terminal (3T) Hanle measurement for two types of sample series, CoFe/SiO{sub 2}/n{sup +}-Si and Cu/SiO{sub 2}/n{sup +}-Si, with various tunnel resistances. Clear Hanle signal and anomalous scaling between spin resistance-area product and tunnel resistance-area product were observed in CoFe/SiO{sub 2}/n{sup +}-Si devices. In order to explore the origin of the Hanle signal and the impurity-assisted tunneling effect on the Hanle signal in our devices, Hanle measurement in Cu/SiO{sub 2}/n{sup +}-Si devices was performed as well. However, no detectable Hanle signal was observed in Cu/SiO{sub 2}/n{sup +}-Si, even though a lot of samples with various tunnel resistances were studied in wide temperature and bias voltage ranges. Through a comparative study, it is found that the impurity-assisted tunneling magnetoresistance mechanism would not play a dominant role in the 3T Hanle signal in CoFe/SiO{sub 2}/n{sup +}-Si tunnel junctions, where the SiO{sub 2} was formed by plasma oxidation to minimize impurities.

  20. 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.

  1. 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.

  2. 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.

  3. Accurate ab initio quartic force fields of cyclic and bent HC2N isomers.

    PubMed

    Inostroza, Natalia; Huang, Xinchuan; Lee, Timothy J

    2011-12-28

    Highly correlated ab initio quartic force fields (QFFs) are used to calculate the equilibrium structures and predict the spectroscopic parameters of three HC(2)N 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 as 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 (PT) (with proper treatment of Fermi resonances) and variational methods to solve the nuclear Schrödinger 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 PT). On the other hand, this procedure (a QFF together with either PT or variational methods) leads to highly accurate fundamental vibrational frequencies and spectroscopic constants for the cyclic and bent singlet isomers of HC(2)N. All three isomers possess significant dipole moments, 3.05 D, 3.06 D, and 1.71 D, 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.

  4. Self-supported fibrous porous aromatic membranes for efficient CO2/N2 separations.

    PubMed

    Meng, Lingbo; Zou, Xiaoqin; Guo, Shukun; Ma, Heping; Zhao, Yongnan; Zhu, Guangshan

    2015-07-22

    In this paper, we describe a new synthesis protocol for the preparation of self-supported hollow fiber membranes composed of porous aromatic framework PAF-56P and PSF. PAF-56P was facilely prepared by the cross-coupling reaction of triangle-shaped cyanuric chloride and linear p-terophenyl monomers. The prepared PAF-56P material possesses an extended conjugated network, the structure of which is confirmed by nuclear magnetic resonance and infrared characterizations, as well as a permanent porosity with a BET surface area of 553.4 m(2) g(-1) and a pore size of 1.2 nm. PAF-56P was subsequently integrated with PSF matrix into PAF-56P/PSF asymmetric hollow fiber membranes via the dry jet-wet quench method employing PAF-56P/PSF suspensions. Scanning electron microscopy studies show that PAF-56P particles are embedded in the PSF matrix to form continuous membranes. Fabricated PAF-56P/PSF membranes were further exploited for CO2 capture, which was exemplified by gas separations of CO2/N2 mixtures. The PAF-56P/PSF membranes show a high selectivity of CO2 over N2 with a separation factor of 38.9 due to the abundant nitrogen groups in the PAF-56P framework. A preferred permeance for CO2 in the binary CO2/N2 gas mixture is obtained in the range of 93-141 GPU due to the large CO2 adsorption capacity and a large pore size of PAF-56P. Additionally, PAF-56P/PSF membranes exhibit excellent thermal and mechanical stabilities, which were examined by thermal analysis and gas separation tests with the dependencies of temperatures and pressures. The merits of high selectivity for CO2, good stability, and easy scale up make PAF-56P/PSF hollow fiber membranes of great interest for the industrial separations of CO2 from the gas exhausts.

  5. 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

  6. 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

  7. Investigation of Gd3N@C2n(40≤n≤44) family by Raman and inelastic electron tunneling spectroscopy

    NASA Astrophysics Data System (ADS)

    Burke, Brian G.; Chan, Jack; Williams, Keith A.; Ge, Jiechao; Shu, Chunying; Fu, Wujun; Dorn, Harry C.; Kushmerick, James G.; Puretzky, Alexander A.; Geohegan, David B.

    2010-03-01

    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 field 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 fingerprint 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 .

  8. Structure, energetics, and bonding of novel potential high energy density materials Rh2(N5)4: A DFT study

    NASA Astrophysics Data System (ADS)

    Tang, Lihong; Bao, Shuangyou; Peng, Jinhui; Li, Kai; Ning, Ping; Guo, Huibin; Zhu, Tingting; Gu, Junjie; Li, Qianshu

    2015-10-01

    Theoretical studies examining a series of binuclear transition metal pentazolides Rh2(N5)4 predict paddle wheel type structures with very short metal-metal distances. Natural bonding orbital analysis indicated that the bonding between the metal atom and the five-membered ring is predominantly ionic for Rh2(N5)4 species, and a high-order metal-metal multiple bonding exists between the two metal atoms. In addition, the presence of the delocalized π orbital plays an important role in the stabilization of Rh2(N5)4. Nucleus independent chemical shift values confirm that the planar N5- exhibits aromaticity. The dissociation energies into mononuclear fragments are predicted for Rh2(N5)4.

  9. Structural diversity of copper-CO2 complexes: infrared spectra and structures of [Cu(CO2)n]- clusters.

    PubMed

    Knurr, Benjamin J; Weber, J Mathias

    2014-11-06

    We  present infrared spectra of  [Cu(CO2)n](-) (n = 2-9) clusters in the wavenumber range 1600-2400 cm(-1). The CO stretching modes in this region encode the structural nature of the cluster core and are interpreted with the aid of density functional theory. We find a variety of core species in [Cu(CO2)n](-) clusters, but the dominant core structure is a [Cu(CO2)2](-) core where the two CO2 ligands are bound to the Cu atom in a bidentate fashion. We compare the results of [Cu(CO2)n](-) clusters to those of other [M(CO2)n](-) clusters (M = Au, Ag, Co, Ni) to establish trends of how the metal-CO2 interaction depends on the metal partner.

  10. Synthesis of TiO2-N/SnO2 heterostructure photocatalyst and its photocatalytic mechanism.

    PubMed

    Cao, Han; Huang, Shaolong; Yu, Yanlong; Yan, Yabin; Lv, Yuekai; Cao, Yaan

    2017-01-15

    A series of TiO2-N/SnO2X heterostructure photocatalysts were synthesized by a hydrolysis-deposition method. The structure, existing states of N and SnO2 heterostructure at the interface of TiO2-N/SnO2X were studied by EADX, XRD, Raman, FT-IR, XPS, and HRTEM. The band structure is investigated by both theoretical calculation and experiment characterization. It was found that the introduction of NOx surface species and SnO2 nanoparticles would enhance the absorption in visible region, increase reactive oxidative species and separate photogenerated electrons and holes efficiently. Therefore, the photocatalytic activity is improved significantly for TiO2-N/SnO2X, compared with TiO2-N and TiO2 under visible and UV light irradiation. This work may offer a new strategy to fabricate new photocatalyst with high photocatalytic performance.

  11. Epigenetic information in gametes: Gaming from before fertilization. Comment on ;Epigenetic game theory: How to compute the epigenetic control of maternal-to-zygotic transition; by Qian Wang et al.

    NASA Astrophysics Data System (ADS)

    Shi, Junchao; Zhang, Xudong; Liu, Ying; Chen, Qi

    2017-03-01

    In their interesting article [1] Wang et al. proposed a mathematical model based on evolutionary game theory [2] to tackle the fundamental question in embryo development, that how sperm and egg interact with each other, through epigenetic processes, to form a zygote and direct successful embryo development. This work is based on the premise that epigenetic reprogramming (referring to the erasure and reconstruction of epigenetic marks, such as DNA methylation and histone modifications) after fertilization might be of paramount importance to maintain the normal development of embryos, a premise we fully agree, given the compelling experimental evidence reported [3]. Wang et al. have specifically chosen to employ the well-studied DNA methylation reprogramming process during mammalian early embryo development, as a basis to develop their mathematical model, namely epigenetic game theory (epiGame). They concluded that the DNA methylation pattern in mammalian early embryo could be formulated and quantified, and their model can be further used to quantify the interactions, such as competition and/or cooperation of expressed genes that maximize the fitness of embryos. The efforts by Wang et al. in quantitatively and systematically analyzing the beginning of life apparently hold value and represent a novel direction for future embryo development research from both theoretical and experimental biologists. On the other hand, we see their theory still at its infancy, because there are plenty more parameters to consider and there are spaces for debates, such as the cases of haploid embryo development [4]. Here, we briefly comment on the dynamic process of epigenetic reprogramming that goes beyond DNA methylation, a dynamic interplay that involves histone modifications, non-coding RNAs, transposable elements et al., as well as the potential input of the various types of 'hereditary' epigenetic information in the gametes - a game that has started before the fertilization.

  12. N-ethyl-N-nitrosourea mutagenesis of a 6- to 11-cM subregion of the Fah-Hbb interval of mouse chromosome 7: Completed testing of 4557 gametes and deletion mapping and complementation analysis of 31 mutations.

    PubMed

    Rinchik, E M; Carpenter, D A

    1999-05-01

    An interval of mouse chromosome (Chr) 7 surrounding the albino (Tyr; c) locus, and corresponding to a long 6- to 11-cM Tyr deletion, has been the target of a large-scale mutagenesis screen with the chemical supermutagen N-ethyl-N-nitrosourea (ENU). A segment of Chr 7, from a mutagenized genome bred from ENU-treated males, was made hemizygous opposite the long deletion for recognition and recovery of new recessive mutations that map within the albino deletion complex. Over 6000 pedigrees were analyzed, and 4557 of these were completely tested for mutations specifying both lethal and gross visible phenotypes. Thirty-one nonclustered mutations were identified and assigned to 10 complementation groups by pairwise trans-complementation crosses. Deletion-mapping analyses, using the extensive series of radiation-induced Tyr deletions, placed the loci defined by each of these complementation groups into defined intervals of the Tyr-region deletion map, which facilitates the identification of each locus on physical and transcription maps of the region. These mutations identified seven new loci and provided new ENU-induced alleles at three previously defined loci. Interestingly, no mutations were recovered that recapitulated three phenotypes defined by analysis of homozygous or partially complementing albino deletions. On the basis of our experience with this screen, we discuss a number of issues (e.g., locus mutability, failure to saturate, number of gametes to screen, allelic series) of concern when application of chemical mutagenesis screens to megabase regions of the mouse genome is considered.

  13. Ionic ASi2N3 (A=Li, Na, K and Rb) stabilized by the covalent Si-N bonding: First-principles calculations

    NASA Astrophysics Data System (ADS)

    Zhang, Huijun; Ren, Jiadong; Wu, Lailei; Zhang, Jingwu

    2017-01-01

    The structural, elastic and electronic properties of LiSi2N3 and its substitutions by Na, K and Rb were investigated through first-principles computations. The expansion of lattice parameters of ASi2N3 from Li, Na, K to Rb is found to be determined by the bond angle of Si-N1-Si, which suggests a possible way to improve the lithium ionic conductivity by substitutions. ASi2N3 (A=Li, Na, K and Rb) shows the similar elastic behaviors, while the electronic band gap gradually decreases from 5.1 to 3.4 eV from LiSi2N3 to RbSi2N3. Interestingly, the analysis of electronic structure, crystal orbital Hamiltonian populations and Bader charges shows that the covalence of Si-N bonding is critical for the stability of ASi2N3 phase. Among ASi2N3 phases, there is a relatively high ionicity in NaSi2N3; the Si-N bond strength in [Si2N3]- net for KSi2N3 and RbSi2N3 is comparable to LiSi2N3, but stronger than NaSi2N3.

  14. 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.

  15. 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.

  16. An extracellular factor regulating expression of the chromosomal aminoglycoside 2'-N-acetyltransferase of Providencia stuartii.

    PubMed

    Rather, P N; Parojcic, M M; Paradise, M R

    1997-08-01

    The chromosomal aac(2')-Ia gene in Providencia stuartii encodes a housekeeping 2'-N-acetyltransferase [AAC(2')-Ia] involved in the acetylation of peptidoglycan. In addition, the AAC(2')-Ia enzyme also acetylates and confers resistance to the clinically important aminoglycoside antibiotics gentamicin, tobramycin, and netilmicin. Expression of the aac(2')-Ia gene was found to be strongly influenced by cell density, with a sharp decrease in aac(2')-Ia mRNA accumulation as cells approached stationary phase. This decrease was mediated by the accumulation of an extracellular factor, designated AR (for acetyltransferase repressing)-factor. AR-factor was produced in both minimal and rich media and acted in a manner that was strongly dose dependent. The activity of AR-factor was also pH dependent, with optimal activity at pH 8.0 and above. Biochemical characterization of conditioned media from P. stuartii has shown that AR-factor is between 500 and 1,000 Da in molecular size and is heat stable. In addition, AR-factor was inactivated by a variety of proteases, suggesting that it may be a small peptide.

  17. Contribution of gentamicin 2'-N-acetyltransferase to the O acetylation of peptidoglycan in Providencia stuartii.

    PubMed

    Payie, K G; Rather, P N; Clarke, A J

    1995-08-01

    A collection of Providencia stuartii mutants which either underexpress or overexpress aac(2')-Ia, the chromosomal gene coding for gentamicin 2'-N-acetyltransferase (EC 2.3.1.59), have been characterized phenotypically as possessing either lower or higher levels of peptidoglycan O acetylation, respectively, than the wild type. These mutants were subjected to both negative-staining and thin-section electron microscopy. P. stuartii PR100, with 42% O acetylation of peptidoglycan compared with 52% O acetylation in the wild type, appeared as irregular rods. In direct contrast, P. stuartii strains PR50.LM3 and PR51, with increased levels of peptidoglycan O acetylation (65 and 63%, respectively), appeared as coccobacilli and chain formers, respectively. Membrane blebbing was also observed with the chain-forming strain PR51. Thin sectioning of this mutant indicated that it was capable of proper constriction and separation. P. stuartii PM1, when grown to mid-exponential phase, did not have altered peptidoglycan O-acetylation levels, and cellular morphology remained similar to that of wild-type strains. However, continued growth into stationary phase resulted in a 15% increase in peptidoglycan O acetylation concomitant with a change of some cells from a rod-shaped to a coccobacillus-shaped morphology. The fact that these apparent morphological changes were directly related to levels of O acetylation support the view that this modification plays a role in the maintenance of peptidoglycan structure, presumably through the control of autolytic activity.

  18. Association of GSTO2 (N142D) Genetic Polymorphism and Acute Rejection of Liver

    PubMed Central

    Khosravi, M.; Saadat, I.; Karimi, M. H.; Malek Hosseini, S. A.

    2016-01-01

    Background: Acute rejection is the main problem in liver transplantation that occurs in the first days or months of transplantation. It includes histological and cellular rejection. Acute histological rejection is confirmed by biopsy. Glutathione S-transferase family is the most important genes in phase II detoxification working in xenobiotic and drug metabolism. GSTO2 is one of the members of this family. GSTO2 (N142D) polymorphism may influence metabolism of immunosuppressive drugs. Objective: To determine if GSTO2 polymorphism has association with acute liver rejection. Methods: The present study included 120 patients with histological-proven acute liver rejection and 182 patients without acute rejection. Both groups were matched for sex and age. To determine variants of GSTO2, we used polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: There was a significant association between the GSTO2 genotype and acute liver rejection (NN: OR: 3.642, 95% CI: 1.179–5.444) and (ND: OR: 2.533, 95% CI: 1.672–8.149) compared to those with DD geneotype. Conclusion: Recipients with either NN or ND genotype for GSTO2 are more likely to develop acute liver rejection compared to those with DD genotype. PMID:27721965

  19. 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.

  20. 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.

  1. 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.

  2. 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%.

  3. 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.

  4. Study of DC Circuit Breaker of H2-N2 Mixture Gas for High Voltage

    NASA Astrophysics Data System (ADS)

    Shiba, Yuji; Morishita, Yukinaga; Kaneko, Shuhei; Okabe, Shigemitsu; Mizoguchi, Hitoshi; Yanabu, Satoru

    Global warming caused by CO2 etc. is a field where the concern is very high. Especially, automobile emissions are problem for it. Therefore, the hybrid car is widely development and used recently. Hybrid car used electric power and gasoline. So, the car reduces CO2. Hybrid car has engine and motor. To rotate the motor, hybrid car has battery. This battery is large capacity. Therefore, the relay should interrupt high DC current for the switch of the motor and the engine. So, hybrid car used hydrogen gas filling relay We studied interruption test for the research of a basic characteristic of hydrogen gas. DC current has not current zero point. So, it is necessary to make the current zero by high arc voltage and forcible current zero point. The loss coefficient and arc voltage of hydrogen is high. Therefore, we studied interruption test for used high arc voltage. We studied interruption test and dielectric breakdown test of air, pure Hydrogen, and Hydrogen- nitrogen mixture gas. As a result, we realized H2-N2(80%-20%) is the best gas.

  5. Structural, electronic and magnetic properties of chevron-type graphene, BN and BC2N nanoribbons

    NASA Astrophysics Data System (ADS)

    Guerra, T.; Azevedo, S.; Kaschny, J. R.

    2017-04-01

    Graphene nanoribbons are predicted to be essential components in future nanoelectronics. The size, edge type, arrangement of atoms and width of nanoribbons drastically change their properties. Boronnitrogencarbon nanoribbons properties are not fully understood so far. In the present contribution it was investigated the structural, electronic and magnetic properties of chevron-type carbon, boron nitride and BC2N nanoribbons, using first-principles calculations. The results indicate that the structural stability is closely related to the discrepancies in the bond lengths, which can induce structural deformations and stress. Such nanoribbons present a wide range of electronic behaviors, depending on their composition and particularities of the atomic arrangement. A net magnetic moment is found for structures that present carbon atoms at the nanoribbon borders. Nevertheless, the calculated magnetic moment depends on the peculiarities of the symmetric arrangement of atoms and imbalance of carbon atoms between different sublattices. It was found that all structures which have a significant energy gap do not present magnetic moment, and vice-versa. Such result indicates the strong correlation between the electronic and magnetic properties of the chevron-type nanoribbons.

  6. Ultem((R))/ZIF-8 mixed matrix hollow fiber membranes for CO2/N-2 separations

    SciTech Connect

    Dai, Y; Johnson, JR; Karvan, O; Sholl, DS; Koros, WJ

    2012-05-15

    Organic-inorganic hybrid (mixed matrix) membranes can potentially extend the separation performance of traditional polymeric materials while maintaining processing convenience. Although many dense films studies have been reported, there have been few reported cases of these materials being successfully extended to asymmetric hollow fibers. In this work we report the first successful production of mixed matrix asymmetric hollow fiber membranes containing metal-organic-framework (MOF) ZIF-8 fillers. Specifically, we have incorporated ZIF-8 into a polyetherimide (Ultem((R)) 1000) matrix and produced dual-layer asymmetric hollow fiber membranes via the dry jet-wet quench method. The outer separating layer of these composite fibers contains 13 wt% (17 vol%) of ZIF-8 filler. These membranes have been tested over a range of temperatures and pressures for a variety of gas pairs. An increase in separation performance for the CO2/N-2 gas pairs was observed for both pure gas and mixed gas feeds. (C) 2012 Elsevier B.V. All rights reserved.

  7. Formation of E-cyanomethamine in a nitrile rich environment

    NASA Astrophysics Data System (ADS)

    Shivani; Misra, Alka; Tandon, Poonam

    2017-01-01

    Recently a new molecule, cyanomethamine, has been detected towards Sagittarius B2(N) (Sgr B2(N)). Studying the formation mechanisms of complex interstellar molecules is difficult. Hence, a theoretical quantum chemical approach for analyzing the reaction mechanism describing the formation of interstellar cyanomethamine through detected interstellar molecules and radicals (NCCN+H) is discussed in the present work. Calculations are performed by using quantum chemical techniques, such as Density Functional Theory (DFT) and Møller-Plesset perturbation (MP2) theory with a 6-311G(d,p) basis set, both in the gas phase and in icy grains. The proposed reaction path (NCCN+H+H) has exothermicity with no barrier which indicates the possibility of cyanomethamine formation in the interstellar medium.

  8. Cadmium complexes bearing (Me2)N^E^O(-) (E = S, Se) organochalcogenoalkoxides and their zinc and mercury analogues.

    PubMed

    Pop, Alexandra; Bellini, Clément; Şuteu, Răzvan; Dorcet, Vincent; Roisnel, Thierry; Carpentier, Jean-François; Silvestru, Anca; Sarazin, Yann

    2017-03-07

    Heteroleptic zinc and cadmium complexes of the type [{(Me2)N^E^O(R2)}M-Nu]n (M = Zn, Cd; E = S, Se; R = CH3, CF3; Nu = N(SiMe3)2, I, Cl; n = 1-2) were prepared by reacting the alcohol proteo-ligands {(Me2)N^E^O(R2)}H with [M(N(SiMe3)2)2] (M = Zn, Cd) or [XMN(SiMe3)2] (M = Zn, X = Cl; M = Cd, X = I) in an equimolar ratio. These group 12 metal complexes were characterised in solution by multinuclear NMR spectroscopy and their solid-state structures were determined by X-ray diffractometry. The ligands {(Me2)N^E^O((CH3)2)}(-) bearing CH3 groups in α position to the alkoxide behave as κ(2)-O,E-bidentate moieties (E = S, Se) and form centro-symmetric dinuclear O-bridged heteroleptic alkoxo-amido complexes both with zinc and cadmium, with four-coordinate metal centres resting in tetrahedral environments. By contrast, complexes supported by the CF3-substituted {(Me2)N^E^O((CF3)2)}(-) crystallise as tetrahedral mononuclear species, with tridentate κ(3)-N,O,E-coordinated ligands. These structural differences resulting from changes in the ligand skeleton and in the electron-donating properties of the alkoxide were also observed in solution. Attempts to prepare congeneric heteroleptic mercury complexes from [Hg(N(SiMe3)2)2] unexpectedly only afforded homoleptic bis(alkoxide)s such as [{(Me2)N^S^O((CF3)2)}2Hg]. Owing to the strong Hg-C bond, treatment of [PhHgN(SiMe3)2] with {(Me2)N^S^O((CF3)2)}H afforded the heteroleptic, T-shaped [{(Me2)N^S^O((CF3)2)}HgPh] mercuric alkoxide upon elimination of hexamethyldisilazane. [{(Me2)N^S^O((CF3)2)}2Hg] and [{(Me2)N^S^O((CF3)2)}HgPh] constitute very rare examples of structurally characterised mercuric alkoxides.

  9. 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%.

  10. First-principle investigation on the thermodynamics of X2N2O (X = C, Si, Ge) compounds

    NASA Astrophysics Data System (ADS)

    Qing-Yun, Xiong; Qi-Xia, Shen; Rui-Zi, Li; Jiang, Shen; Fu-Yang, Tian

    2016-02-01

    The structures under different pressures, elastic properties, electronic structures and lattice vibrations of the X2N2O (X = C, Si, Ge) compounds are investigated by using the first-principle method. Based on the phonon density of state, the thermodynamic properties of the present compounds are studied under different pressures and at different temperatures. The structural parameters including the bond lengths and bond angles are in agreement with available experimental measurements and theoretical calculations. We employ the elastic theory to calculate the nine independent elastic constants (Ci j) and the derived elastic moduli (B, G, E, v). Results indicate that these X2N2O (X = C, Si, Ge) compounds are mechanically stable and show the brittle behaviors. The electronic properties of the present compounds are analyzed by using the band structure and density of states. The phonon dispersion calculations imply that the present compounds are dynamically stable. Based on the quasi-harmonic approximation, the calculations of the specific heat indicate that the temperature in a range of 0 K-1500 K and pressure in a range of 0 GPa-40 GPa have a large effect on the thermal quantities of Ge2N2O, compared with on those of the C2N2O and Si2N2O compounds. Project supported by the Fundamental Research Funds for the Central Universities, China (Grant No. FRF-TP-14-029Al).

  11. 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

  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. 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.

  14. Gravitational wave memory in dS4+2n and 4D cosmology

    NASA Astrophysics Data System (ADS)

    Chu, Y.-Z.

    2017-02-01

    We argue that massless gravitons in all even dimensional de Sitter (dS) spacetimes higher than two admit a linear memory effect arising from their propagation inside the null cone. Assume that gravitational waves (GWs) are being generated by an isolated source, and over only a finite period of time {η\\text{i}}≤slant η ≤slant {η\\text{f}} . Outside of this time interval, suppose the shear-stress of the GW source becomes negligible relative to its energy-momentum and its mass quadrupole moments settle to static values. We then demonstrate, the transverse-traceless (TT) GW contribution to the perturbation of any dS4+2n written in a conformally flat form ({{a}2}{ημ ν}\\text{d}{{x}μ}\\text{d}{{x}ν} )—after the source has ceased and the primary GW train has passed—amounts to a spacetime constant shift in the flat metric proportional to the difference between the TT parts of the source’s final and initial mass quadrupole moments. As a byproduct, we present solutions to Einstein’s equations linearized about de Sitter backgrounds of all dimensions greater than three. We then point out there is a similar but approximate tail induced linear GW memory effect in 4D matter dominated universes. Our work here serves to improve upon and extend the 4D cosmological results of Chu (2015 Phys. Rev. D 92 124038), which in turn preceded complementary work by Bieri et al (2015 arXiv:1509.01296) and by Kehagias and Riotto (2016 arXiv:1602.02653).

  15. T(t,2n)4He Neutron Spectrum from Inertial Confinement Implosions

    NASA Astrophysics Data System (ADS)

    McNabb, Dennis; Bacher, Andy; Brune, Carl; Caggiano, Jac; Gatu-Johnson, Maria; Sayre, Dan; ICF Stellar Rates Team

    2013-10-01

    Measurements of the T(t,2n)4He reaction (TT) have been conducted using high-purity tritium, gas-filled capsules in ICF implosions at the NIF and OMEGA facilities. Neutron spectra were measured using two instruments: the neutron-time-of-flight (nTOF) and the Magnetic Recoil Spectrometer. The nTOF spectra represent a significant improvement in energy resolution and statistics over previous measurements, and afford the first definitive observation of a small, narrow peak starting at the 9.44 MeV endpoint resulting from sequential decay through the ground state of 5He at low reaction energies Ecm < 100 keV. However, most of the TT reaction produces a broad neutron spectrum from 0-9.5 MeV. To describe the spectrum, an R-matrix model that accounts for interferences from fermion symmetry and intermediate states has been developed. This model can describe the entire spectrum via sequential decay through l = 1 states in 5He, which differs from previous interpretations. Work is in collaboration with V. Yu Glebov, R. Hatarik, D. L. Bleuel, D. T. Casey, C. J. Cerjan, M. J. Eckart, R. J. Fortner, J. A. Frenje, G. P. Grim, C. Hagmann, J. P. Knauer, J. L. Kline, J. M. McNaney, J. M. Mintz, M. J. Moran, A. Nikroo, T. Phillips, J. E. Pino, B. A. Remington, D. P. Rowley, D. H. Schneider, V. A. Smalyuk, W. Stoeffl, R. E. Tipton, S. V. Weber, C. B. Yeamans, C. K. Li, M. J.-E. Manuel, D. D. Meyerhofer, R. D. Petrasso, P. B. Radha, T. C. Sangster, N. Sinenian, F. H. Seguin, and A. B. Zylstra.

  16. 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

  17. 239Pu(n,2n) 238Pu cross section inferred from IDA calculations and GEANIE measurements

    SciTech Connect

    Chen, H; Ormand, W E; Dietrich, F S

    2000-09-01

    This report presents the latest {sup 239}Pu(n,2n){sup 238}Pu cross sections inferred from calculations performed with the nuclear reaction-modeling code system, IDA, coupled with experimental measurements of partial {gamma}-ray cross sections for incident neutron energies ranging from 5.68 to 17.18 MeV. It is found that the inferred {sup 239}Pu(n,2n){sup 238}Pu cross section peaks at E{sub inc} {approx} 11.4 MeV with a peak value of approximately 326 mb. At E{sub inc} {approx} 14 MeV, the inferred {sup 239}Pu(n,2n){sup 238}Pu cross section is found to be in good agreement with previous radio-chemical measurements by Lockheed. However, the shape of the inferred {sup 239}Pu(n,2n){sup 238}Pu cross section differs significantly from previous evaluations of ENDL, ENDF/B-V and ENDF/B-VI. In our calculations, direct, preequilibrium, and compound reactions are included. Also considered in the modeling are fission and {gamma}-cascade processes in addition to particle emission. The main components of physics adopted and the parameters used in our calculations are discussed. Good agreement of the inferred {sup 239}Pu(n,2n){sup 238}Pu cross sections derived separately from IDA and GNASH calculations is shown. The two inferences provide an estimate of variations in the deduced {sup 239}Pu(n,2n){sup 238}Pu cross section originating from modeling.

  18. 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.

  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. 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.

  1. Mechanistic control of product selectivity. Reactions between cis-/trans cis-/trans-[OsVI(tpy)(Cl)2(N)]+ and triphenylphosphine sulfide.

    PubMed

    Huynh, M H; White, P S; Meyer, T J

    2000-06-26

    Reactions between the Os(VI)-nitrido complexes cis- and trans-[Os(VI)(tpy)(Cl)2(N)]+ (tpy is 2,2':6',2"-terpyridine) and triphenylphosphine sulfide, SPPh3, give the corresponding Os(IV)-phosphoraniminato, [Os(IV)(tpy)(Cl)2(NPPh3)]+, and Os(II)-thionitrosyl, [Os(II)(tpy)(Cl)2(NS)]+, complexes as products. The Os-N bond length and Os-N-P angle in cis-[Os(IV)(tpy)(Cl)2(NPPh3)](PF6) are 2.077(6) A and 138.4(4) degrees. The rate law for formation of cis- and trans-[Os(IV)(tpy)(Cl)2(NPPh3)]+ is first order in both [Os(VI)(tpy)(Cl)2(N)]+ and SPPh3 with ktrans(25 degrees C, CH3CN) = 24.6 +/- 0.6 M(-1) s(-1) and kcis(25 degrees C, CH3CN) = 0.84 +/- 0.09 M(-1) s(-1). As found earlier for [Os(II)(tpm)(Cl)2(NS)]+, both cis- and trans-[Os(II)(tpy)(Cl)2(NS)]+ react with PPh3 to give [Os(IV)(tpy)(Cl)2(NPPh3)]+ and SPPh3. For both complexes, the reaction is first order in each reagent with ktrans(25 degrees C, CH3CN) = (6.79 +/- 0.08) x 10(2) M(-1) s(-1) and kcis(25 degrees C, CH3CN) = (2.30 +/- 0.07) x 10(2) M(-1) s(-1). The fact that both reactions occur rules out mechanisms involving S atom transfer. These results can be explained by invoking a common intermediate, [Os(IV)(tpy)(Cl)2(NSPPh3)]+, which undergoes further reaction with PPh3 to give [Os(IV)(tpy)(Cl)2(NPPh3)]+ and SPPh3 or with [Os(VI)(tpy)(Cl)2(N)]+ to give [Os(IV)(tpy)(Cl)2(NPPh3)]+ and [Os(II)(tpy)(Cl)2(NS)]+.

  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. 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

  4. Spectroscopic evidence on improvement in complex formation of O2N2 aza-crown macrocyclic ligands with Cu(II) acetate upon incorporation with [60]Fullerene

    NASA Astrophysics Data System (ADS)

    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.

  5. 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.

  6. The effects of preparation conditions for a BaNbO2 N photocatalyst on its physical properties.

    PubMed

    Hisatomi, Takashi; Katayama, Chisato; Teramura, Kentaro; Takata, Tsuyoshi; Moriya, Yosuke; Minegishi, Tsutomu; Katayama, Masao; Nishiyama, Hiroshi; Yamada, Taro; Domen, Kazunari

    2014-07-01

    BaNbO2 N is a semiconductor photocatalyst active for water oxidation under visible-light irradiation up to λ=740 nm. It is important to understand the nitridation processes of precursor materials to form BaNbO2 N to tune the physical properties and improve the photocatalytic activity. Comprehensive experiments and analyses of temperatures, durations, ammonia flow rates, and barium/niobium ratios in the precursor during the nitridation process reveals that faster ammonia flow rates and higher barium/niobium ratios in the precursors help to suppress reduction of pentavalent niobium ions in the nitridation products and that the use of a precursor prepared by a soft-chemistry route allows the production of BaNbO2 N at lower temperatures in shorter times than the use of physical mixtures of BaCO3 and Nb2 O5 because the niobium species is dispersed among the barium species. BaNbO2 N prepared by the soft-chemistry route exhibits comparatively higher activity than that prepared from physical mixtures of BaCO3 and Nb2 O5 , probably because of lower nitridation temperatures, which suppress excessive dissociation of ammonia, and thereby reduce pentavalent niobium ions, and intimate interaction of niobium and barium sources, which lowers the densities of mid-gap states associated with defects.

  7. 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.

  8. 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.

  9. 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.

  10. Bioelectrochemical Haber-Bosch Process: An Ammonia-Producing H2 /N2 Fuel Cell.

    PubMed

    Milton, Ross D; Cai, Rong; Abdellaoui, Sofiene; Leech, Dónal; De Lacey, Antonio L; Pita, Marcos; Minteer, Shelley D

    2017-03-01

    Nitrogenases are the only enzymes known to reduce molecular nitrogen (N2 ) to ammonia (NH3 ). By using methyl viologen (N,N'-dimethyl-4,4'-bipyridinium) to shuttle electrons to nitrogenase, N2 reduction to NH3 can be mediated at an electrode surface. The coupling of this nitrogenase cathode with a bioanode that utilizes the enzyme hydrogenase to oxidize molecular hydrogen (H2 ) results in an enzymatic fuel cell (EFC) that is able to produce NH3 from H2 and N2 while simultaneously producing an electrical current. To demonstrate this, a charge of 60 mC was passed across H2  /N2 EFCs, which resulted in the formation of 286 nmol NH3  mg(-1) MoFe protein, corresponding to a Faradaic efficiency of 26.4 %.

  11. Steric effect in the energy transfer reaction of Ar(3P2)+N2

    NASA Astrophysics Data System (ADS)

    Watanabe, D.; Ohoyama, H.; Matsumura, T.; Kasai, T.

    2006-08-01

    Steric effect for N2(C,Πu3) formation in the energy transfer reaction of Ar(P23)+N2 was directly measured by using an oriented Ar(P23,MJ=2) beam at a collision energy of 0.06eV. The N2(C,Πu3) chemiluminescence intensity was measured as a function of the magnetic orientation field direction in the collision frame. A significant alignment effect on the energy transfer probability was observed. The relative reactivity for each magnetic substate in the collision frame σ∣MJ'∣ was determined to be σ∣2∣:σ∣1∣:σ0=0.50:0.60:1.00. It is suggested that the observed steric effect is primarily due to the favorable configuration of the 3p orbital for the efficient overlap with the 2σu molecular orbital of N2.

  12. Sexual polyploidization in plants – cytological mechanisms and molecular regulation

    PubMed Central

    De Storme, Nico; Geelen, Danny

    2013-01-01

    In the plant kingdom, events of whole genome duplication or polyploidization are generally believed to occur via alterations of the sexual reproduction process. Thereby, diploid pollen and eggs are formed that contain the somatic number of chromosomes rather than the gametophytic number. By participating in fertilization, these so-called 2n gametes generate polyploid offspring and therefore constitute the basis for the establishment of polyploidy in plants. In addition, diplogamete formation, through meiotic restitution, is an essential component of apomixis and also serves as an important mechanism for the restoration of F1 hybrid fertility. Characterization of the cytological mechanisms and molecular factors underlying 2n gamete formation is therefore not only relevant for basic plant biology and evolution, but may also provide valuable cues for agricultural and biotechnological applications (e.g. reverse breeding, clonal seeds). Recent data have provided novel insights into the process of 2n pollen and egg formation and have revealed multiple means to the same end. Here, we summarize the cytological mechanisms and molecular regulatory networks underlying 2n gamete formation, and outline important mitotic and meiotic processes involved in the ectopic induction of sexual polyploidization. PMID:23421646

  13. 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

  14. Common File Formats.

    PubMed

    Mills, Lauren

    2014-03-21

    An overview of the many file formats commonly used in bioinformatics and genome sequence analysis is presented, including various data file formats, alignment file formats, and annotation file formats. Example workflows illustrate how some of the different file types are typically used.

  15. Experimental and theoretical investigations of the redox behavior of the heterodichalcogenido ligands [(EP(i)Pr2)(TeP(i)Pr2)N](-) (E = S, Se): cyclic cations and acyclic dichalcogenide dimers.

    PubMed

    Robertson, Stuart D; Chivers, Tristram; Tuononen, Heikki M

    2008-11-17

    The two-electron oxidation of the lithium salts of the heterodichalcogenidoimidodiphosphinate anions [(EP (i)Pr 2)(TeP (i)Pr 2)N] (-) ( 1a, E = S; 1b, E = Se) with iodine yields cyclic cations [(EP (i)Pr 2)(TeP (i)Pr 2)N] (+) as their iodide salts [(SP (i)Pr 2)(TeP (i)Pr 2)N]I ( 2a) and [(SeP (i)Pr 2)(TeP (i)Pr 2)N]I ( 2b). The five-membered rings in 2a and 2b both display an elongated E-Te bond as a consequence of an interaction between tellurium and the iodide anion. One-electron reduction of 2a and 2b with cobaltocene produces the neutral dimers (EP (i)Pr 2NP (i)Pr 2Te-) 2 ( 3a, E = S; 3b, E = Se), which are connected exclusively through a Te-Te bond. Two-electron reduction of 2a and 2b with 2 equiv of cobaltocene regenerates the corresponding dichalcogenidoimidodiphosphinate anions as ion-separated cobaltocenium salts Cp 2Co[(EP (i)Pr 2)(TeP (i)Pr 2)N] ( 4a, E = S; 4b, E = Se). The ditellurido analogue Cp 2Co[(TeP (i)Pr 2) 2N] ( 4c) has been prepared in the same manner for comparison. Density functional theory calculations reveal that the preferential interaction of the iodide anion with tellurium is determined by the polarization of the lowest unoccupied molecular orbital [sigma*(E-Te)] of the cations in 2a and 2b toward tellurium and that the formation of the dimers 3a and 3b with a central Te-Te linkage is energetically more favorable than the structural isomers with either E-Te or E-E bonds. Compounds 2a, 2b, 3a, 3b, 4a, 4b, and 4c have been characterized in solution by multinuclear NMR spectroscopy and in the solid state by X-ray crystallography.

  16. 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.

  17. Crystal Structures of the L1, L2, N, and O States of pharaonis Halorhodopsin

    PubMed Central

    Kouyama, Tsutomu; Kawaguchi, Haruki; Nakanishi, Taichi; Kubo, Hiroki; Murakami, Midori

    2015-01-01

    Halorhodopsin from Natronomonas pharaonis (pHR) functions as a light-driven halide ion pump. In the presence of halide ions, the photochemical reaction of pHR is described by the scheme: K→ L1 → L2 → N → O → pHR′ → pHR. Here, we report light-induced structural changes of the pHR-bromide complex observed in the C2 crystal. In the L1-to-L2 transition, the bromide ion that initially exists in the extracellular vicinity of retinal moves across the retinal Schiff base. Upon the formation of the N state with a bromide ion bound to the cytoplasmic vicinity of the retinal Schiff base, the cytoplasmic half of helix F moves outward to create a water channel in the cytoplasmic interhelical space, whereas the extracellular half of helix C moves inward. During the transition from N to an N-like reaction state with retinal assuming the 13-cis/15-syn configuration, the translocated bromide ion is released into the cytoplasmic medium. Subsequently, helix F relaxes into its original conformation, generating the O state. Anion uptake from the extracellular side occurs when helix C relaxes into its original conformation. These structural data provide insight into the structural basis of unidirectional anion transport. PMID:26039169

  18. Formate Formation and Formate Conversion in Biological Fuels Production

    PubMed Central

    Crable, Bryan R.; Plugge, Caroline M.; McInerney, Michael J.; Stams, Alfons J. M.

    2011-01-01

    Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO2 and providing carbon-neutral or carbon-negative strategies to cope with dwindling fossil fuel supplies and environmental impact. Formate is an important intermediate in the methanogenic breakdown of complex organic material and serves as an important precursor for biological fuels production in the form of methane, hydrogen, and potentially methanol. Formate is produced by either CoA-dependent cleavage of pyruvate or enzymatic reduction of CO2 in an NADH- or ferredoxin-dependent manner. Formate is consumed through oxidation to CO2 and H2 or can be further reduced via the Wood-Ljungdahl pathway for carbon fixation or industrially for the production of methanol. Here, we review the enzymes involved in the interconversion of formate and discuss potential applications for biofuels production. PMID:21687599

  19. Regulation of male sex determination: genital ridge formation and Sry activation in mice.

    PubMed

    Tanaka, Satomi S; Nishinakamura, Ryuichi

    2014-12-01

    Sex determination is essential for the sexual reproduction to generate the next generation by the formation of functional male or female gametes. In mammals, primary sex determination is commenced by the presence or absence of the Y chromosome, which controls the fate of the gonadal primordium. The somatic precursor of gonads, the genital ridge is formed at the mid-gestation stage and gives rise to one of two organs, a testis or an ovary. The fate of the genital ridge, which is governed by the differentiation of somatic cells into Sertoli cells in the testes or granulosa cells in the ovaries, further determines the sex of an individual and their germ cells. Mutation studies in human patients with disorders of sex development and mouse models have revealed factors that are involved in mammalian sex determination. In most of mammals, a single genetic trigger, the Y-linked gene Sry (sex determination region on Y chromosome), regulates testicular differentiation. Despite identification of Sry in 1990, precise mechanisms underlying the sex determination of bipotential genital ridges are still largely unknown. Here, we review the recent progress that has provided new insights into the mechanisms underlying genital ridge formation as well as the regulation of Sry expression and its functions in male sex determination of mice.

  20. Triazine containing N-rich microporous organic polymers for CO2 capture and unprecedented CO2/N2 selectivity

    NASA Astrophysics Data System (ADS)

    Bhunia, Subhajit; Bhanja, Piyali; Das, Sabuj Kanti; Sen, Tapas; Bhaumik, Asim

    2017-03-01

    Targeted synthesis of microporous adsorbents for CO2 capture and storage is very challenging in the context of remediation from green house gases. Herein we report two novel N-rich microporous networks SB-TRZ-CRZ and SB-TRZ-TPA by extensive incorporation of triazine containing tripodal moiety in the porous polymer framework. These materials showed excellent CO2 storage capacities: SB-TRZ-CRZ displayed the CO2 uptake capacity of 25.5 wt% upto 1 bar at 273 K and SB-TRZ-TPA gave that of 16 wt% under identical conditions. The substantial dipole quadruple interaction between network (polar triazine) and CO2 boosts the selectivity for CO2/N2. SB-TRZ-CRZ has this CO2/N2 selectivity ratio of 377, whereas for SB-TRZ-TPA it was 97. Compared to other porous polymers, these materials are very cost effective, scalable and very promising material for clean energy application and environmental issues.

  1. BiVO4/TiO2(N2) Nanotubes Heterojunction Photoanode for Highly Efficient Photoelectrocatalytic Applications

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Bai, Jing; Li, Yunpo; Zeng, Qingyi; Li, Jinhua; Zhou, Baoxue

    2017-04-01

    We report the development of a novel visible response BiVO4/TiO2(N2) nanotubes photoanode for photoelectrocatalytic applications. The nitrogen-treated TiO2 nanotube shows a high carrier concentration rate, thus resulting in a high efficient charge transportation and low electron-hole recombination in the TiO2-BiVO4. Therefore, the BiVO4/TiO2(N2) NTs photoanode enabled with a significantly enhanced photocurrent of 2.73 mA cm-2 (at 1 V vs. Ag/AgCl) and a degradation efficiency in the oxidation of dyes under visible light. Field emission scanning electron microscopy, X-ray diffractometry, energy-dispersive X-ray spectrometer, and UV-Vis absorption spectrum were conducted to characterize the photoanode and demonstrated the presence of both metal oxides as a junction composite.

  2. Interaction of nickel with carbon dioxide in [Ni(CO2)(n)](-) clusters studied by infrared spectroscopy.

    PubMed

    Knurr, Benjamin J; Weber, J Mathias

    2014-09-25

    We present infrared photodissociation spectra of [Ni(CO2)n](-) clusters (n = 2-8) in the wavenumber region of 1000-2400 cm(-1) using the antisymmetric stretching vibrational modes of the CO2 units in the clusters as structural probes. We use density functional theory to aid in the interpretation of our experimental results. The dominant spectral signatures arise from a core ion composed of a nickel atom and two CO2 ligands bound to the Ni atom in a bidentate fashion, while the rest of the CO2 molecules in the cluster play the role of solvent. Other core structures are observed as well but as minor contributors. The results for [Ni(CO2)n](-) clusters are discussed in the context of other anionic transition- metal complexes with CO2.

  3. High-Permeance Room-Temperature Ionic-Liquid-Based Membranes for CO2/N-2 Separation

    SciTech Connect

    Zhou, JS; Mok, MM; Cowan, MG; McDanel, WM; Carlisle, TK; Gin, DL; Noble, RD

    2014-12-24

    We have developed and fabricated thin-film composite (TFC) membranes with an active layer consisting of a room-temperature ionic liquid/polymerized (room-temperature ionic liquid) [i.e., (RTIL)/poly(RTIL)] composite material. The resulting membrane has a CO2 permeance of 6100 +/- 400 GPU (where 1 GPU = 10(-6) cm(3)/(cm(2) s cmHg)) and an ideal CO2/N-2 selectivity of 22 +/- 2. This represents a new membrane with state-of-the-art CO2 permeance and good CO2/N-2 selectivity. To our knowledge, this is the first example of a TFC gas separation membrane composed of an RTIL-containing active layer.

  4. Boss/Sev signaling from germline to soma restricts germline-stem-cell-niche formation in the anterior region of Drosophila male gonads.

    PubMed

    Kitadate, Yu; Shigenobu, Shuji; Arita, Kayo; Kobayashi, Satoru

    2007-07-01

    Drosophila germline stem cells are regulated by the somatic microenvironment, or "niche," which ensures that the stem cells can both self-renew and produce functional gametes throughout adult life. However, despite its prime importance, little is known about how niche formation is regulated during gonadal development. Here, we demonstrate that a receptor tyrosine kinase, Sevenless (Sev), is required to ensure that the niche develops in the anterior region of the male embryonic gonads. Sev is expressed in somatic cells within the posterior region of the gonads. Sev is activated by a ligand, Bride of sevenless (Boss), which is expressed by the germline, to prevent ectopic niche differentiation in the posterior gonadal somatic cells. Thus, we propose that signal transduction from germline to soma restricts expansion of the germline-stem-cell niche in the gonads.

  5. The first structurally characterized metal (kappa(2)N,P)-phosphinohydrazides: the key to understanding the intramolecular rearrangement R2P-NR'-NR'-M --> R'N=PR2-NR'-M. Metalloderivatives of diisopropylphosphinohydrazines: synthesis and properties.

    PubMed

    Kornev, Alexander N; Belina, Natalia V; Sushev, Vyacheslav V; Fukin, Georgy K; Baranov, Evgenii V; Kurskiy, Yuriy A; Poddelskii, Andrei I; Abakumov, Gleb A; Lönnecke, Peter; Hey-Hawkins, Evamarie

    2009-06-15

    A number of novel phosphinohydrazines, iPr(2)P-NPh-NPh-H (1), iPr(2)P-NH-NH-PiPr(2) (2), iPr(2)P-NMe-NH-PiPr(2) (3), and H-NMe-NH-PiPr(2) (4), were prepared and characterized. The interaction of 1 with 1 equiv of n-BuLi afforded a complex compound [Li(DME)(3)][Li{(NPh-NPh-PiPr(2))-kappaN}(2)] (5). The reaction of 5 with NiBr(2) resulted in the formation of the first stable transition metal phosphinohydrazide [Ni{(NPh-NPh-PiPr(2))-kappa(2)N,P}(2)] (6). Similarly, the cobalt(II) derivative [Co{(NPh-NPh-PiPr(2))-kappa(2)N,P}(2)] (7) was prepared by the reaction of 1 with Co[N(SiMe(3))(2)](2). An X-ray study reveals formation of the complexes containing elongated N-N bonds (1.443(1), 1.466(2), and 1.470(2) A for 5, 6, and 7, respectively) as compared with the starting material 1 (1.407(1) A). Nickel phosphinohydrazide 6 has a square-planar cis configuration; the cobalt complex 7 possesses a square-planar centrosymmetric trans configuration. The half-sandwich nickel(II) complex [CpNi{(NPh-NPh-PiPr(2))-kappa(2)N,P}] (8) was prepared by prolonged heating of phosphinohydrazine 1 with NiCp(2) in toluene. The lithiation of 3 with n-BuLi resulted in the formation of an iminophosphoranate [LiN=PiPr(2)-NMe-PiPr(2)] (13) (in situ), which is the product of insertion of a PiPr(2) group into the nitrogen-nitrogen bond. The hydrolysis of 13 followed by the addition of CoCl(2) gave the phosphino-iminophosphoranato complex [CoCl(2){(HN=PiPr(2)-NMe-PiPr(2))-kappa(2)N,P}] (15) according to X-ray investigation. The phosphinohydrazine 3 reacted with FeX(2) in toluene to form adducts (1:1) [FeX(2){(PiPr(2)-NMe-NH-PiPr(2))-kappa(2)P,P'}] (X = Cl (9), Br (10)), while CoCl(2) gave the complex salt [{Co(PiPr(2)-NMe-NH-PiPr(2))-kappa(2)P,P'}(2)(mu-Cl)(3)][CoCl(3)(THF)] (11). A THF solution of complex 11 shows thermochromic behavior.

  6. Synthesis of 2-n-(hexadecanoyl)-amino-4-nitrophenyl phosphorylcholine-hydroxide, a chromogenic substrate for assaying sphingomyelinase activity.

    PubMed

    Gal, A E; Fash, F J

    1976-02-01

    2-N-(Hexadecanoyl)-amino-4-nitrophenyl phosphorylcholine-hydroxide a compound resembling sphingomyelin is synthesized. It is cleaved by sphingomyelinase to the chromogenic N-acylaminonitrophenyl moiety. Phospholipase C preparations do not hydrolyze this compound. The starting material is 2-amino-4-nitrophenol which when acylated with palmitoyl chloride yields the hexadecananilide. Reaction with beta-bromoethylphosphoryldichloride gives the phosphate which is quaternized with trimethylamine to give the title compound.

  7. Equation of state for Eu-doped SrSi{sub 2}O{sub 2}N{sub 2}

    SciTech Connect

    Ermakova, Olga; Paszkowicz, Wojciech Kaminska, Agata; Minikayev, Roman; Nowakowska, Małgorzata; Carlson, Stefan; Li, Guogang; Liu, Ru-Shi; Suchocki, Andrzej

    2014-07-07

    α-SrSi{sub 2}O{sub 2}N{sub 2} is one of the recently studied oxonitridosilicates applicable in optoelectronics, in particular in white LEDs. Its elastic properties remain unknown. A survey of literature shows that, up to now, nine oxonitridosilicate materials have been identified. For most of these compounds, doped with rare earths and manganese, a luminescence has been reported at a wavelength characteristic for the given material; all together cover a broad spectral range. The present study focuses on the elastic properties of one of these oxonitridosilicates, the Eu-doped triclinic α-SrSi{sub 2}O{sub 2}N{sub 2}. High-pressure powder diffraction experiments are used in order to experimentally determine, for the first time, the equation of state of this compound. The in situ experiment was performed for pressures ranging up to 9.65 GPa, for Eu-doped α-SrSi{sub 2}O{sub 2}N{sub 2} sample mounted in a diamond anvil cell ascertaining the hydrostatic compression conditions. The obtained experimental variation of volume of the triclinic unit cell of α-SrSi{sub 2}O{sub 2}N{sub 2}:Eu with rising pressure served for determination of the Birch-Murnaghan equation of state. The determined above quoted bulk modulus is 103(5) GPa, its first derivative is 4.5(1.1). The above quoted bulk modulus value is found to be comparable to that of earlier reported oxynitrides of different composition.

  8. Alkyl group as entropy reservoir in an MMX chain complex, Pt2(n-PenCS2)4I.

    PubMed

    Saito, Kazuya; Ikeuchi, Satoaki; Nakazawa, Yasuhiro; Sato, Akane; Mitsumi, Minoru; Yamashita, Takami; Toriumi, Koshiro; Sorai, Michio

    2005-02-24

    Heat capacity of halogen-bridged one-dimensional binuclear metal complex (so-called MMX chain) having four n-pentyl groups, Pt2(n-PenCS2)4I, was measured by adiabatic calorimetry. A first-order phase transition was observed at 207.4 K when measurement was made after cooling from room temperature. The enthalpy and entropy of transition were determined to be 10.19 kJ mol(-1) and 49.1 J K(-1) mol(-1), respectively. A monotropic phase transition was observed at 324 K on heating, and the entropy of transition was essentially null. The sample once heated above 324 K never returned to the initial phase at room temperature and underwent a higher-order phase transition at 173 K and a first-order phase transition at 220.5 K. The enthalpy and entropy of the first-order phase transition were estimated to be 11.6 kJ mol(-1) and 52.4 J K(-1) mol(-1), respectively. The magnitude of the entropy gain at the phase transition from the initial room-temperature phase to the high-temperature phase at 324 K shows that in Pt2(n-PenCS2)4I a large amount of entropy reserved in alkyl chain is transferred to dithiocarboxylato groups upon the phase transition, as in the cases of Pt2(n-PrCS2)4I and Pt2(n-BuCS2)4I.

  9. Nqrs Data for C24H46I2N6O2P2Sn (Subst. No. 1589)

    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 C24H46I2N6O2P2Sn (Subst. No. 1589)

  10. Novel 2N bit bipolar photonic digital-to-analog converter based on optical DQPSK modulation coupled with differential detection.

    PubMed

    Liao, Jinxin; Wen, He; Zheng, Xiaoping; Zhang, Hanyi; Guo, Yili; Zhou, Bingkun

    2012-05-01

    A novel 2N bit bipolar photonic digital-to-analog converter (PDAC) scenario based on the optical differential quadrature phase shift keying (ODQPSK) modulation coupled with differential detection is proposed. Compared with other proposed schemes, this bipolar PDAC has a greater dynamic range and a larger noise margin with good scalabilities both in speed and resolution. We demonstrate a 4 bit PDAC in a proof-of-principle experiment at a sampling rate of 2.5 GS/s.

  11. Structural, spectroscopic aspects, and electronic properties of (TiO2)n clusters: a study based on the use of natural algorithms in association with quantum chemical methods.

    PubMed

    Ganguly Neogi, Soumya; Chaudhury, Pinaki

    2014-01-05

    In this article, we propose a stochastic search-based method, namely genetic algorithm (GA) and simulated annealing (SA) in conjunction with density functional theory (DFT) to evaluate global and local minimum structures of (TiO2)n clusters with n = 1-12. Once the structures are established, we evaluate the infrared spectroscopic modes, cluster formation energy, vertical excitation energy, vertical ionization potential, vertical electron affinity, highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps, and so forth. We show that an initial determination of structure using stochastic techniques (GA/SA), also popularly known as natural algorithms as their working principle mimics certain natural processes, and following it up with density functional calculations lead to high-quality structures for these systems. We have shown that the clusters tend to form three-dimensional networks. We compare our results with the available experimental and theoretical results. The results obtained from SA/GA-DFT technique agree well with available theoretical and experimental data of literature.

  12. Aberrant Classopollis pollen reveals evidence for unreduced (2n) pollen in the conifer family Cheirolepidiaceae during the Triassic–Jurassic transition

    PubMed Central

    Kürschner, Wolfram M.; Batenburg, Sietske J.; Mander, Luke

    2013-01-01

    Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad morphology and the size of the conifer pollen type Classopollis extracted from sediments of the Triassic–Jurassic transition, 200 Ma. Classopollis producing Cheirolepidiaceae were one of the most dominant and diverse groups of conifers during the Mesozoic. We show that aberrant pollen Classopollis tetrads, triads and dyads, and the large variation in pollen size indicates the presence of unreduced (2n) pollen, which is one of the main mechanisms in modern polyploid formation. Polyploid speciation may explain the high variability of growth forms and adaptation of these conifers to different environments and their resistance to extreme growth conditions. We suggest that polyploidy may have also reduced the extinction risk of these conifers during the End-Triassic biotic crisis. PMID:23926159

  13. Aberrant Classopollis pollen reveals evidence for unreduced (2n) pollen in the conifer family Cheirolepidiaceae during the Triassic-Jurassic transition.

    PubMed

    Kürschner, Wolfram M; Batenburg, Sietske J; Mander, Luke

    2013-10-07

    Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad morphology and the size of the conifer pollen type Classopollis extracted from sediments of the Triassic-Jurassic transition, 200 Ma. Classopollis producing Cheirolepidiaceae were one of the most dominant and diverse groups of conifers during the Mesozoic. We show that aberrant pollen Classopollis tetrads, triads and dyads, and the large variation in pollen size indicates the presence of unreduced (2n) pollen, which is one of the main mechanisms in modern polyploid formation. Polyploid speciation may explain the high variability of growth forms and adaptation of these conifers to different environments and their resistance to extreme growth conditions. We suggest that polyploidy may have also reduced the extinction risk of these conifers during the End-Triassic biotic crisis.

  14. The quest for complex molecules in space. Searches for cyanides related to n-propyl cyanide in Sgr B2(N)

    NASA Astrophysics Data System (ADS)

    Muller, H. S. P.; Belloche, A.; Menten, K. M.; Coutens, A.; Walters, A.; Grabow, J. U.; Schlemmer, S.

    2011-05-01

    A molecular line survey was carried out with the IRAM 30 m telecope toward the prolific hot core Sgr B2(N) in order to explore its molecular complexity. The entire 3 mm range as well as selected regions at 2 and 1.3 mm were covered. Notable results include the detections of aminoacetonitrile, ethyl formate, n-propyl cyanide, and the singly substituted 13C isotopologs of vinyl cyanide. There exists a branched isomer of n-propyl cyanide: iso-propyl cyanide. A search for this isomer in our line survey required a laboratory spectroscopic investigation beforehand. Even though promising emission features have been found for this as well as other, related molecules, there are rather few uncontaminated lines. Overlap by other emission or some absorption features occurs frequently, and uncertainties about the position of the baseline also contribute to considering detections to be inconclusive. Nevertheless, the determination of upper limits or abundances among isomers and related molecules will help to contrain astrochemical pathways. We will present our results and discuss promising strategies to search for complex molecules in space.

  15. Influence of the ionic liquid [C4mpy][Tf2N] on the structure of the miniprotein Trp-cage.

    PubMed

    Baker, Joseph L; Furbish, Jeffrey; Lindberg, Gerrick E

    2015-11-01

    We examine the effect of the ionic liquid [C4mpy][Tf2N] on the structure of the miniprotein Trp-cage and contrast these results with the behavior of Trp-cage in water. We find the ionic liquid has a dramatic effect on Trp-cage, though many similarities with aqueous Trp-cage are observed. We assess Trp-cage folding by monitoring root mean square deviation from the crystallographic structure, radius of gyration, proline cis/trans isomerization state, protein secondary structure, amino acid contact formation and distance, and native and non-native contact formation. Starting from an unfolded configuration, Trp-cage folds in water at 298 K in less than 500 ns of simulation, but has very little mobility in the ionic liquid at the same temperature, which can be ascribed to the higher ionic liquid viscosity. At 365 K, the mobility of the ionic liquid is increased and initial stages of Trp-cage folding are observed, however Trp-cage does not reach the native folded state in 2 μs of simulation in the ionic liquid. Therefore, in addition to conventional molecular dynamics, we also employ scaled molecular dynamics to expedite sampling, and we demonstrate that Trp-cage in the ionic liquid does closely approach the aqueous folded state. Interestingly, while the reduced mobility of the ionic liquid is found to restrict Trp-cage motion, the ionic liquid does facilitate proline cis/trans isomerization events that are not seen in our aqueous simulations.

  16. ECO2N - A New TOUGH2 Fluid Property Module for Studies of CO2Storage in Saline Aquifers

    SciTech Connect

    Pruess, Karsten; Spycher, Nicholas

    2006-04-17

    ECO2N is a fluid property module for the TOUGH2 simulator (Version 2.0) that was designed for applications to geologic storage of CO{sub 2} in saline aquifers. It includes a comprehensive description of the thermodynamics and thermophysical properties of H{sub 2}O-NaCl-CO{sub 2} mixtures, that reproduces fluid properties largely within experimental error for the temperature, pressure and salinity conditions of interest(10 C {le} T {le} 110 C; P {le} 600 bar; salinity up to full halite saturation). Flow processes can be modeled isothermally or non-isothermally, and phase conditions represented may include a single (aqueous or CO{sub 2}-rich) phase, as well as two-phase mixtures. Fluid phases may appear or disappear in the course of a simulation, and solid salt may precipitate or dissolve. ECO2N can model super- as well as sub-critical conditions, but it does not make a distinction between liquid and gaseous CO{sub 2}. This paper highlights significant features of ECO2N, and presents illustrative applications.

  17. Role of Si2N2O in the passive oxidation of chemically-vapor-deposited Si3N4

    NASA Technical Reports Server (NTRS)

    Ogbuji, Linus U. J. T.

    1992-01-01

    The results of two-step oxidation experiments on chemically-vapor-deposited Si3N4 and SiC at 1350 C show that a correlation exists between the presence of a Si2N2O interphase and the strong oxidation resistance of Si3N4. During normal oxidation, k sub p for SiC was 15 times higher than that for Si3N4, and the oxide scale on Si3N4 was found by SEM and TEM to contain a prominent Si2N2O inner layer. However, when oxidized samples are annealed in Ar for 1.5 h at 1500 C and reoxidized at 1350 C as before, three things happen: the oxidation k sub p increases over 55-fold for Si3N4, and 3.5-fold for SiC; the Si3N4 and SiC oxidize with nearly equal k sub p's; and, most significantly, the oxide scale on Si3N4 is found to be lacking an inner Si2N2O layer. The implications of this correlation for the competing models of Si3N4 oxidation are discussed.

  18. Memantine inhibits α3β2-nAChRs-mediated nitrergic neurogenic vasodilation in porcine basilar arteries.

    PubMed

    Lee, Reggie Hui-Chao; Tseng, Ting-Yi; Wu, Celeste Yin-Chieh; Chen, Po-Yi; Chen, Mei-Fang; Kuo, Jon-Son; Lee, Tony Jer-Fu

    2012-01-01

    Memantine, an NMDA receptor antagonist used for treatment of Alzheimer's disease (AD), is known to block the nicotinic acetylcholine receptors (nAChRs) in the central nervous system (CNS). In the present study, we examined by wire myography if memantine inhibited α3β2-nAChRs located on cerebral perivascular sympathetic nerve terminals originating in the superior cervical ganglion (SCG), thus, leading to inhibition of nicotine-induced nitrergic neurogenic dilation of isolated porcine basilar arteries. Memantine concentration-dependently blocked nicotine-induced neurogenic dilation of endothelium-denuded basilar arteries without affecting that induced by transmural nerve stimulation, sodium nitroprusside, or isoproterenol. Furthermore, memantine significantly inhibited nicotine-elicited inward currents in Xenopous oocytes expressing α3β2-, α7- or α4β2-nAChR, and nicotine-induced calcium influx in cultured rat SCG neurons. These results suggest that memantine is a non-specific antagonist for nAChR. By directly inhibiting α3β2-nAChRs located on the sympathetic nerve terminals, memantine blocks nicotine-induced neurogenic vasodilation of the porcine basilar arteries. This effect of memantine is expected to reduce the blood supply to the brain stem and possibly other brain regions, thus, decreasing its clinical efficacy in the treatment of Alzheimer's disease.

  19. In situ Fe2N@N-doped porous carbon hybrids as superior catalysts for oxygen reduction reaction.

    PubMed

    Huang, Xiaoxiao; Yang, Ziyu; Dong, Bing; Wang, Yazhou; Tang, Tianyu; Hou, Yanglong

    2017-03-22

    Developing efficient and economical noble-metal free catalysts for oxygen reduction reaction (ORR) is one of the essential factors for the industrialization of fuel cells. Recent studies on transition metal ORR catalysts have become the priority to practical low-temperature fuel cells. Herein, we proposed a novel in situ design, Fe2N nanoparticles (NPs) in an N doped porous carbon matrix (Fe2N@NPC) derived from me