Does the mechanism of sex determination constrain the potential for sex manipulation? A test in geckos with contrasting sex-determining systems

Science.gov (United States)

Kratochvíl, Lukáš; Kubička, Lukáš; Landová, Eva

2008-03-01

The concentration of yolk steroids was suggested to influence offspring gender in oviparous animals subject to both temperature-dependent sex determination (TSD) and genotypic sex determination (GSD). However, the proposed mechanisms of steroid effects are thought to differ between TSD and GSD: a direct effect of oestrogens on gonad feminisation in TSD species vs a differential induction of male-producing or female-producing gametes in GSD species. Geckos offer an ideal opportunity for testing these suggested mechanisms. Closely related gecko species differ in their modes of sex determination. They lay clutches of two synchronously formed eggs; both eggs share equal steroid levels. If identical hormonal composition and environment during vitellogenesis, gravidity and incubation determine the sex of the progeny, siblings should share the same gender in both TSD and GSD geckos. We found strong support for this prediction in a TSD gecko species. Among clutches that were incubated at the temperature that produced both sexes, there were no clutches with siblings of the opposite sex. On the other hand, about half of the clutches yielded siblings of the opposite sex in four GSD species. These results suggest that sex-determining systems constrain the ability of the female to produce single-sex siblings and, hence, it seems that the GSD mechanism constrains the opportunities for sex ratio manipulation in geckos via yolk steroid manipulation.

A Review of Sex Determining Mechanisms in Geckos (Gekkota: Squamata)

OpenAIRE

Gamble, T.

2010-01-01

Geckos are a species-rich clade of reptiles possessing diverse sex determining mechanisms. Some species possess genetic sex determination, with both male and female heterogamety, while other species have temperature-dependent sex determination. I compiled information from the literature on the taxonomic distribution of these sex determining mechanisms in geckos. Using phylogenetic data from the literature, I reconstructed the minimum number of transitions among these sex determining mechanism...

Adrenal-kidney-gonad complex measurements may not predict gonad-specific changes in gene expression patterns during temperature-dependent sex determination in the red-eared slider turtle (Trachemys scripta elegans).

Science.gov (United States)

Ramsey, Mary; Crews, David

2007-08-01

Many turtles, including the red-eared slider turtle (Trachemys scripta elegans) have temperature-dependent sex determination in which gonadal sex is determined by temperature during the middle third of incubation. The gonad develops as part of a heterogenous tissue complex that comprises the developing adrenal, kidney, and gonad (AKG complex). Owing to the difficulty in excising the gonad from the adjacent tissues, the AKG complex is often used as tissue source in assays examining gene expression in the developing gonad. However, the gonad is a relatively small component of the AKG, and gene expression in the adrenal-kidney (AK) compartment may interfere with the detection of gonad-specific changes in gene expression, particularly during early key phases of gonadal development and sex determination. In this study, we examine transcript levels as measured by quantitative real-time polymerase chain reaction for five genes important in slider turtle sex determination and differentiation (AR, ERalpha, ERbeta, aromatase, and Sf1) in AKG, AK, and isolated gonad tissues. In all cases, gonad-specific gene expression patterns were attenuated in AKG versus gonad tissue. All five genes were expressed in the AK in addition to the gonad at all stages/temperatures. Inclusion of the AK compartment masked important changes in gonadal gene expression. In addition, AK and gonad expression patterns are not additive, and gonadal gene expression cannot be predicted from intact AKG measurements. (c) 2007 Wiley-Liss, Inc.

Transcriptomic responses to environmental temperature by turtles with temperature-dependent and genotypic sex determination assessed by RNAseq inform the genetic architecture of embryonic gonadal development.

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Radhakrishnan, Srihari; Literman, Robert; Neuwald, Jennifer; Severin, Andrew; Valenzuela, Nicole

2017-01-01

Vertebrate sexual fate is decided primarily by the individual's genotype (GSD), by the environmental temperature during development (TSD), or both. Turtles exhibit TSD and GSD, making them ideal to study the evolution of sex determination. Here we analyze temperature-specific gonadal transcriptomes (RNA-sequencing validated by qPCR) of painted turtles (Chrysemys picta TSD) before and during the thermosensitive period, and at equivalent stages in soft-shell turtles (Apalone spinifera-GSD), to test whether TSD's and GSD's transcriptional circuitry is identical but deployed differently between mechanisms. Our data show that most elements of the mammalian urogenital network are active during turtle gonadogenesis, but their transcription is generally more thermoresponsive in TSD than GSD, and concordant with their sex-specific function in mammals [e.g., upregulation of Amh, Ar, Esr1, Fog2, Gata4, Igf1r, Insr, and Lhx9 at male-producing temperature, and of β-catenin, Foxl2, Aromatase (Cyp19a1), Fst, Nf-kb, Crabp2 at female-producing temperature in Chrysemys]. Notably, antagonistic elements in gonadogenesis (e.g., β-catenin and Insr) were thermosensitive only in TSD early-embryos. Cirbp showed warm-temperature upregulation in both turtles disputing its purported key TSD role. Genes that may convert thermal inputs into sex-specific development (e.g., signaling and hormonal pathways, RNA-binding and heat-shock) were differentially regulated. Jak-Stat, Nf-κB, retinoic-acid, Wnt, and Mapk-signaling (not Akt and Ras-signaling) potentially mediate TSD thermosensitivity. Numerous species-specific ncRNAs (including Xist) were differentially-expressed, mostly upregulated at colder temperatures, as were unannotated loci that constitute novel TSD candidates. Cirbp showed warm-temperature upregulation in both turtles. Consistent transcription between turtles and alligator revealed putatively-critical reptilian TSD elements for male (Sf1, Amh, Amhr2) and female (Crabp2 and Hspb1

Transcriptomic responses to environmental temperature by turtles with temperature-dependent and genotypic sex determination assessed by RNAseq inform the genetic architecture of embryonic gonadal development.

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Srihari Radhakrishnan

Full Text Available Vertebrate sexual fate is decided primarily by the individual's genotype (GSD, by the environmental temperature during development (TSD, or both. Turtles exhibit TSD and GSD, making them ideal to study the evolution of sex determination. Here we analyze temperature-specific gonadal transcriptomes (RNA-sequencing validated by qPCR of painted turtles (Chrysemys picta TSD before and during the thermosensitive period, and at equivalent stages in soft-shell turtles (Apalone spinifera-GSD, to test whether TSD's and GSD's transcriptional circuitry is identical but deployed differently between mechanisms. Our data show that most elements of the mammalian urogenital network are active during turtle gonadogenesis, but their transcription is generally more thermoresponsive in TSD than GSD, and concordant with their sex-specific function in mammals [e.g., upregulation of Amh, Ar, Esr1, Fog2, Gata4, Igf1r, Insr, and Lhx9 at male-producing temperature, and of β-catenin, Foxl2, Aromatase (Cyp19a1, Fst, Nf-kb, Crabp2 at female-producing temperature in Chrysemys]. Notably, antagonistic elements in gonadogenesis (e.g., β-catenin and Insr were thermosensitive only in TSD early-embryos. Cirbp showed warm-temperature upregulation in both turtles disputing its purported key TSD role. Genes that may convert thermal inputs into sex-specific development (e.g., signaling and hormonal pathways, RNA-binding and heat-shock were differentially regulated. Jak-Stat, Nf-κB, retinoic-acid, Wnt, and Mapk-signaling (not Akt and Ras-signaling potentially mediate TSD thermosensitivity. Numerous species-specific ncRNAs (including Xist were differentially-expressed, mostly upregulated at colder temperatures, as were unannotated loci that constitute novel TSD candidates. Cirbp showed warm-temperature upregulation in both turtles. Consistent transcription between turtles and alligator revealed putatively-critical reptilian TSD elements for male (Sf1, Amh, Amhr2 and female (Crabp2 and

Temperature-dependent sex-reversal by a transformer-2 gene-edited mutation in the spotted wing drosophila, Drosophila suzukii.

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Li, Jianwei; Handler, Alfred M

2017-09-28

Female to male sex reversal was achieved in an emerging agricultural insect pest, Drosophila suzukii, by creating a temperature-sensitive point mutation in the sex-determination gene, transformer-2 (tra-2), using CRISPR/Cas9 (clustered regularly interspaced palindromic repeats/CRISPR-associated) homology-directed repair gene-editing. Ds-tra-2 ts2 mutants developed as normal fertile XX and XY adults at permissive temperatures below 20 °C, but at higher restrictive temperatures (26 to 29 °C) chromosomal XX females developed as sterile intersexuals with a predominant male phenotype, while XY males developed with normal morphology, but were sterile. The temperature-dependent function of the Ds-TRA-2 ts2 protein was also evident by the up- and down-regulation of female-specific Ds-Yolk protein 1 (Ds-Yp1) gene expression by temperature shifts during adulthood. This study confirmed the temperature-dependent function of a gene-edited mutation and provides a new method for the more general creation of conditional mutations for functional genomic analysis in insects, and other organisms. Furthermore, it provides a temperature-dependent system for creating sterile male populations useful for enhancing the efficacy of biologically-based programs, such as the sterile insect technique (SIT), to control D. suzukii and other insect pest species of agricultural and medical importance.

Transitions between sex-determining systems in reptiles and amphibians.

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Sarre, Stephen D; Ezaz, Tariq; Georges, Arthur

2011-01-01

Important technological advances in genomics are driving a new understanding of the evolution of sex determination in vertebrates. In particular, comparative chromosome mapping in reptiles has shown an intriguing distribution of homology in sex chromosomes across reptile groups. When this new understanding is combined with the widespread distribution of genetic and temperature-dependent sex-determination mechanisms among reptiles, it is apparent that transitions between modes have occurred many times, as they have for amphibians (particularly between male and female heterogamety). It is also likely that thermosensitivity in sex determination is a key factor in those transitions in reptiles, and possibly in amphibians too. New models of sex determination involving temperature thresholds are providing the framework for the investigation of transitions and making possible key predictions about the homologies and sex-determination patterns expected among taxa in these groups. Molecular cytogenetics and other genomic approaches are essential to providing the fundamental material necessary to make advances in this field.

Distinct sperm nucleus behaviors between genotypic and temperature-dependent sex determination males are associated with replication and expression-related pathways in a gynogenetic fish.

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Zhu, Yao-Jun; Li, Xi-Yin; Zhang, Jun; Li, Zhi; Ding, Miao; Zhang, Xiao-Juan; Zhou, Li; Gui, Jian-Fang

2018-06-05

Coexistence and transition of diverse sex determination strategies have been revealed in some ectothermic species, but the variation between males caused by different sex determination strategies and the underlying mechanism remain unclear. Here, we used the gynogenetic gibel carp (Carassius gibelio) with both genotypic sex determination (GSD) and temperature-dependent sex determination (TSD) strategies to illustrate this issue. We found out that males of GSD and TSD in gibel carp had similar morphology, testicular histology, sperm structure and sperm vitality. However, when maternal individuals were mated with males of GSD, sperm nucleus swelling and fusing with the female pronucleus were observed in the fertilized eggs. On the contrary, when maternal individuals were mated with males of TSD, sperm nucleus remained in the condensed status throughout the whole process. Subsequently, semen proteomics analysis unveiled that DNA replication and gene expression-related pathways were inhibited in the sperm from males of TSD compared to males of GSD, and most differentially expressed proteins associated with DNA replication, transcription and translation were down-regulated. Moreover, via BrdU incorporation and immunofluorescence detection, male nucleus replication was revealed to be present in the fertilized eggs by the sperm from males of GSD, but absent in the fertilized eggs by the sperm from males of TSD. These findings indicate that DNA replication and gene expression-related pathways are associated with the distinct sperm nucleus development behaviors in fertilized eggs in response to the sperm from males of GSD and TSD. And this study is the first attempt to screen the differences between males determined via GSD and TSD in gynogenetic species, which might give a hint for understanding evolutionary adaption of diverse sex determination mechanisms in unisexual vertebrates.

A Review of Sex Determining Mechanisms in Geckos (Gekkota: Squamata)

Science.gov (United States)

Gamble, T.

2010-01-01

Geckos are a species-rich clade of reptiles possessing diverse sex determining mechanisms. Some species possess genetic sex determination, with both male and female heterogamety, while other species have temperature-dependent sex determination. I compiled information from the literature on the taxonomic distribution of these sex determining mechanisms in geckos. Using phylogenetic data from the literature, I reconstructed the minimum number of transitions among these sex determining mechanisms with parsimony-based ancestral state reconstruction. While only a small number of gecko species have been characterized, numerous changes among sex determining mechanisms were inferred. This diversity, coupled with the high frequency of transitions, makes geckos excellent candidates as a model clade for the study of vertebrate sex determination and evolution. PMID:20234154

The platelet-derived growth factor signaling system in snapping turtle embryos, Chelydra serpentina: potential role in temperature-dependent sex determination and testis development.

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Rhen, Turk; Jangula, Adam; Schroeder, Anthony; Woodward-Bosh, Rikki

2009-05-01

The platelet-derived growth factor (Pdgf) signaling system is known to play a significant role during embryonic and postnatal development of testes in mammals and birds. In contrast, genes that comprise the Pdgf system in reptiles have never been cloned or studied in any tissue, let alone developing gonads. To explore the potential role of PDGF ligands and their receptors during embryogenesis, we cloned cDNA fragments of Pdgf-A, Pdgf-B, and receptors PdgfR-alpha and PdgfR-beta in the snapping turtle, a reptile with temperature-dependent sex determination (TSD). We then compared gene expression profiles in gonads from embryos incubated at a male-producing temperature to those from embryos at a female-producing temperature, as well as between hatchling testes and ovaries. Expression of Pdgf-B mRNA in embryonic gonads was significantly higher at a male temperature than at a female temperature, but there was no difference between hatchling testes and ovaries. This developmental pattern was reversed for Pdgf-A and PdgfR-alpha mRNA: expression of these genes did not differ in embryos, but diverged in hatchling testes and ovaries. Levels of PdgfR-beta mRNA in embryonic gonads were not affected by temperature and did not differ between testes and ovaries. However, expression of both receptors increased at least an order of magnitude from the embryonic to the post-hatching period. Finally, we characterized expression of these genes in several other embryonic tissues. The brain, heart, and liver displayed unique expression patterns that distinguished these tissues from each other and from intestine, lung, and muscle. Incubation temperature had a significant effect on expression of PdgfR-alpha and PdgfR-beta in the heart but not other tissues. Together, these findings demonstrate that temperature has tissue specific effects on the Pdgf system and suggest that Pdgf signaling is involved in sex determination and the ensuing differentiation of testes in the snapping turtle.

Effect of hormonal manipulation on sociosexual behavior in adult female leopard geckos (Eublepharis macularius), a species with temperature-dependent sex determination.

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Flores, D L; Crews, D

1995-12-01

Aggressive and sexual behavior in the adult leopard gecko (Eublepharis macularius), a species with temperature-dependent sex determination (TSD), is influenced by the temperature experienced as an egg, as well as by prenatal and perinatal hormones. This study focused on the effects of hormonal manipulation of adult female leopard geckos from different incubation temperatures. Following ovariectomy, females from both all-female (26 degrees C) and male-biased (32.5 degrees C) incubation temperatures exhibited a significant decrease in high-posture (HP) aggression toward male and female stimulus animals. Testosterone treatment attenuated this decrease in HP aggression toward female but not toward male stimulus animals. Ovariectomy also resulted in a loss in attractiveness in both groups of females. Following treatment with testosterone, over 50% of the females were attacked by male stimulus animals, suggesting a change in the pheromonal cues normally secreted by females. Unmanipulated females never exhibit tail vibrations, a male-typical courtship behavior. However, following ovariectomy with testosterone treatment, half of the females from both incubation temperatures exhibited this behavior, indicating an activational effect of testosterone. An effect of incubation temperature on aggression was evident with females from the male-biased incubation temperature exhibiting a greater likelihood of aggression compared to females from the all-female incubation temperature. This effect continued to be detected after hormone manipulation. Ovariectomized females from the all-female incubation temperature were less aggressive even with testosterone treatment toward males, whereas females from the male-biased incubation temperature showed no significant decline in aggression following testosterone treatment, suggesting that individuals from different incubation temperatures may have different sensitivities to hormones.

Commentary Sex determination

Indian Academy of Sciences (India)

PRAKASH KUMAR G

2008-01-31

ZW is reserved for female heterogamety.) The Radder et al study used lab incubation regimes that mimic temperature profiles of cool natural nests, so temperature probably determines sex at least occasionally in nature.

Delimitation of the embryonic thermosensitive period for sex determination using an embryo growth model reveals a potential bias for sex ratio prediction in turtles.

Science.gov (United States)

Girondot, Marc; Monsinjon, Jonathan; Guillon, Jean-Michel

2018-04-01

The sexual phenotype of the gonad is dependent on incubation temperature in many turtles, all crocodilians, and some lepidosaurians. At hatching, identification of sexual phenotype is impossible without sacrificing the neonates. For this reason, a general method to infer sexual phenotype from incubation temperatures is needed. Temperature influences sex determination during a specific period of the embryonic development, starting when the gonad begins to form. At constant incubation temperatures, this thermosensitive period for sex determination (TSP) is located at the middle third of incubation duration (MTID). When temperature fluctuates, the position of the thermosensitive period for sex determination can be shifted from the MTID because embryo growth is affected by temperature. A method is proposed to locate the thermosensitive period for sex determination based on modelling the embryo growth, allowing its precise identification from a natural regime of temperatures. Results from natural nests and simulations show that the approximation of the thermosensitive period for sex determination to the middle third of incubation duration may create a quasi-systematic bias to lower temperatures when computing the average incubation temperature during this period and thus a male-bias for sex ratio estimate. Copyright © 2018 Elsevier Ltd. All rights reserved.

Genotypic sex determination enabled adaptive radiations of extinct marine reptiles.

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Organ, Chris L; Janes, Daniel E; Meade, Andrew; Pagel, Mark

2009-09-17

Adaptive radiations often follow the evolution of key traits, such as the origin of the amniotic egg and the subsequent radiation of terrestrial vertebrates. The mechanism by which a species determines the sex of its offspring has been linked to critical ecological and life-history traits but not to major adaptive radiations, in part because sex-determining mechanisms do not fossilize. Here we establish a previously unknown coevolutionary relationship in 94 amniote species between sex-determining mechanism and whether a species bears live young or lays eggs. We use that relationship to predict the sex-determining mechanism in three independent lineages of extinct Mesozoic marine reptiles (mosasaurs, sauropterygians and ichthyosaurs), each of which is known from fossils to have evolved live birth. Our results indicate that each lineage evolved genotypic sex determination before acquiring live birth. This enabled their pelagic radiations, where the relatively stable temperatures of the open ocean constrain temperature-dependent sex determination in amniote species. Freed from the need to move and nest on land, extreme physical adaptations to a pelagic lifestyle evolved in each group, such as the fluked tails, dorsal fins and wing-shaped limbs of ichthyosaurs. With the inclusion of ichthyosaurs, mosasaurs and sauropterygians, genotypic sex determination is present in all known fully pelagic amniote groups (sea snakes, sirenians and cetaceans), suggesting that this mode of sex determination and the subsequent evolution of live birth are key traits required for marine adaptive radiations in amniote lineages.

Sex determination in mythology and history.

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Mittwoch, Ursula

2005-02-01

The history of ideas on how the sexes became divided spans at least three thousand years. The biblical account of the origin of Eve, and the opinions of the philosophers of classical Greece, have unexpected bearings on present-day ideas. The scientific study of sex determination can be said to have begun in the 17th century with the discovery of spermatozoa, but the origin and function of the "spermatic animalcules" eluded investigators until 1841. The mammalian egg was discovered in 1827, and in the last quarter of the century fertilization was observed. The view current at that time, that sex determination was under environmental control, gave way to the idea of chromosomal determination in the first quarter of the 20th century. The study of human and other mammalian chromosomes during the third quarter of the century, and the discovery of sex-chromosome abnormalities, emphasized the importance of the Y chromosome for male sex determination. The last quarter of the century witnessed a hunt for the "testis-determining" gene, thought to be responsible for the differentiation of Sertoli cells, and culminating in the isolation of SRY (Sry in the mouse). However, an increasing number of additional genes and growth factors were found to be required for the establishment of male sex. During the same period evidence emerged that male development was accompanied by enhanced growth, both of gonads and whole embryos. An unexpected finding was the demonstration of temperature-dependent sex determination in reptiles. With the advent of the 21st century, it was shown that Sry induces cell proliferation in fetal mouse gonads, and it has been suggested that male sex differentiation in mammals requires a higher metabolic rate. These insights could lead to a better understanding and improved treatment of abnormalities of sexual development.

Allelic variant in the anti-Müllerian hormone gene leads to autosomal and temperature-dependent sex reversal in a selected Nile tilapia line.

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Stephan Wessels

Full Text Available Owing to the demand for sustainable sex-control protocols in aquaculture, research in tilapia sex determination is gaining momentum. The mutual influence of environmental and genetic factors hampers disentangling the complex sex determination mechanism in Nile tilapia (Oreochromis niloticus. Previous linkage analyses have demonstrated quantitative trait loci for the phenotypic sex on linkage groups 1, 3, and 23. Quantitative trait loci for temperature-dependent sex reversal similarly reside on linkage group 23. The anti-Müllerian hormone gene (amh, located in this genomic region, is important for sexual fate in higher vertebrates, and shows sexually dimorphic expression in Nile tilapia. Therefore this study aimed at detecting allelic variants and marker-sex associations in the amh gene. Sequencing identified six allelic variants. A significant effect on the phenotypic sex for SNP ss831884014 (p<0.0017 was found by stepwise logistic regression. The remaining variants were not significantly associated. Functional annotation of SNP ss831884014 revealed a non-synonymous amino acid substitution in the amh protein. Consequently, a fluorescence resonance energy transfer (FRET based genotyping assay was developed and validated with a representative sample of fish. A logistic linear model confirmed a highly significant effect of the treatment and genotype on the phenotypic sex, but not for the interaction term (treatment: p<0.0001; genotype: p<0.0025. An additive genetic model proved a linear allele substitution effect of 12% in individuals from controls and groups treated at high temperature, respectively. Moreover, the effect of the genotype on the male proportion was significantly higher in groups treated at high temperature, giving 31% more males on average of the three genotypes. In addition, the groups treated at high temperature showed a positive dominance deviation (+11.4% males. In summary, marker-assisted selection for amh variant ss831884014

Longevity enhances selection of environmental sex determination.

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Bull, J J; Bulmer, M G

1989-12-01

Environmental sex determination (ESD) is a mechanism in which an individual develops as male or female largely in response to some environmental effect experienced early in life. Its forms range from sex determination by egg incubation temperature in reptiles to sex determination of photoperiod in amphipods. Previous theoretical work as suggested that ESD is favored by natural selection if the fitness consequences of the early environmental experience differ for males and females, so that an individual benefits by being male under some conditions and female under others. A drawback of ESD is that it enables climatic changes to influence the population sex ratio, and such fluctuations select against ESD. This study employed numerical analyses to investigate the balance between these two opposing forces. The negative impact of climatic fluctuations appears to depend greatly on species longevity: substantial between-year fluctuations are of little consequence in selecting against ESD in long-lived species because annual sex ratio fluctuations tend to cancel and thus alter the total population sex ratio only slightly. Thus, if a species is sufficiently long-lived, extreme ESD can be maintained despite only a weak advantage. This result offers one explanation for the failure to demonstrate an advantage for the extreme forms of ESD observed in reptiles.

Heritable Variation for Sex Ratio under Environmental Sex Determination in the Common Snapping Turtle (Chelydra Serpentina)

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Janzen, F. J.

1992-01-01

The magnitude of quantitative genetic variation for primary sex ratio was measured in families extracted from a natural population of the common snapping turtle (Chelydra serpentina), which possesses temperature-dependent sex determination (TSD). Eggs were incubated at three temperatures that produced mixed sex ratios. This experimental design provided estimates of the heritability of sex ratio in multiple environments and a test of the hypothesis that genotype X environment (G X E) interactions may be maintaining genetic variation for sex ratio in this population of C. serpentina. Substantial quantitative genetic variation for primary sex ratio was detected in all experimental treatments. These results in conjunction with the occurrence of TSD in this species provide support for three critical assumptions of Fisher's theory for the microevolution of sex ratio. There were statistically significant effects of family and incubation temperature on sex ratio, but no significant interaction was observed. Estimates of the genetic correlations of sex ratio across environments were highly positive and essentially indistinguishable from +1. These latter two findings suggest that G X E interaction is not the mechanism maintaining genetic variation for sex ratio in this system. Finally, although substantial heritable variation exists for primary sex ratio of C. serpentina under constant temperatures, estimates of the effective heritability of primary sex ratio in nature are approximately an order of magnitude smaller. Small effective heritability and a long generation time in C. serpentina imply that evolution of sex ratios would be slow even in response to strong selection by, among other potential agents, any rapid and/or substantial shifts in local temperatures, including those produced by changes in the global climate. PMID:1592234

Temperature-dependent sex-reversal by a transformer-2 gene-edited mutation in the spotted wing drosophila, Drosophila suzukii

Science.gov (United States)

Female to male sex reversal was achieved in an emerging agricultural insect pest, Drosophila suzukii, by creating a temperature-sensitive point mutation in the sex-determination gene, transformer-2 (tra-2) using CRISPR/Cas9 (clustered regularly interspaced palindromic repeats/ CRISPR-associated) hom...

Effects of age and sociosexual experience on the morphology and metabolic capacity of brain nuclei in the leopard gecko (Eublepharis macularius), a lizard with temperature-dependent sex determination.

Science.gov (United States)

Crews, D; Coomber, P; Gonzalez-Lima, F

1997-05-30

In vertebrates having sex chromosomes, sexual behavior is influenced by steroid hormones throughout life as well as by the cumulative experiences of the individual. Because males and females differ genetically as well as hormonally, it would be valuable to distinguish the contribution of sex-specific genes from hormones. In addition, since animals age as they gain sociosexual experience, but do not necessarily gain sociosexual experience as they age, it is important to separate the effects of age from those attributable to experience. The leopard gecko is a lizard lacking sex chromosomes, depending instead upon the temperature during incubation to establish gonadal sex. This effectively removes sex-specific genetic influences from any study of sexual differentiation. Eggs were incubated at either 26 degrees C or 32.5 degrees C, temperatures that produce only female hatchlings or a male-biased sex ratio, respectively. By raising geckoes in isolation and then housing some animals together in breeding groups at different ages after they attained sexual maturity, it was possible to assess the relative effects of age and sociosexual experience on the volume and metabolic capacity of limbic and non-limbic brain areas. In general, males showed more changes compared to females. For example, there was a decrease with age in the volume of the preoptic area and the ventromedial hypothalamus in males, but not in females. Both age and sociosexual experience influenced cytochrome oxidase activity in these and other brain areas. Experienced animals had greater metabolic capacity in nuclei functionally associated with sociosexual behavior in lizards and other vertebrates. For example, cytochrome oxidase activity was higher in the anterior hypothalamus of males, in the ventromedial hypothalamus of both males and females from the male-biased incubation temperature, and in the preoptic area of females from both incubation temperatures. These differences were not paralleled by

DNA methylation of the gonadal aromatase (cyp19a promoter is involved in temperature-dependent sex ratio shifts in the European sea bass.

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Laia Navarro-Martín

2011-12-01

Full Text Available Sex ratio shifts in response to temperature are common in fish and reptiles. However, the mechanism linking temperature during early development and sex ratios has remained elusive. We show in the European sea bass (sb, a fish in which temperature effects on sex ratios are maximal before the gonads form, that juvenile males have double the DNA methylation levels of females in the promoter of gonadal aromatase (cyp19a, the enzyme that converts androgens into estrogens. Exposure to high temperature increased the cyp19a promoter methylation levels of females, indicating that induced-masculinization involves DNA methylation-mediated control of aromatase gene expression, with an observed inverse relationship between methylation levels and expression. Although different CpGs within the sb cyp19a promoter exhibited different sensitivity to temperature, we show that the increased methylation of the sb cyp19a promoter, which occurs in the gonads but not in the brain, is not a generalized effect of temperature. Importantly, these effects were also observed in sexually undifferentiated fish and were not altered by estrogen treatment. Thus, methylation of the sb cyp19a promoter is the cause of the lower expression of cyp19a in temperature-masculinized fish. In vitro, induced methylation of the sb cyp19a promoter suppressed the ability of SF-1 and Foxl2 to stimulate transcription. Finally, a CpG differentially methylated by temperature and adjacent to a Sox transcription factor binding site is conserved across species. Thus, DNA methylation of the aromatase promoter may be an essential component of the long-sought-after mechanism connecting environmental temperature and sex ratios in vertebrate species with temperature-dependent sex determination.

DETERMINATION OF TEMPERATURE DISTRIBUTION FOR ANNULAR FINS WITH TEMPERATURE DEPENDENT THERMAL CONDUCTIVITY BY HPM

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Davood Domairry Ganji

2011-01-01

Full Text Available In this paper, homotopy perturbation method has been used to evaluate the temperature distribution of annular fin with temperature-dependent thermal conductivity and to determine the temperature distribution within the fin. This method is useful and practical for solving the nonlinear heat transfer equation, which is associated with variable thermal conductivity condition. The homotopy perturbation method provides an approximate analytical solution in the form of an infinite power series. The annular fin heat transfer rate with temperature-dependent thermal conductivity has been obtained as a function of thermo-geometric fin parameter and the thermal conductivity parameter describing the variation of the thermal conductivity.

Climate-driven population divergence in sex-determining systems

NARCIS (Netherlands)

Pen, Ido; Uller, Tobias; Feldmeyer, Barbara; Harts, Anna; While, Geoffrey M.; Wapstra, Erik

2010-01-01

Sex determination is a fundamental biological process, yet its mechanisms are remarkably diverse(1,2). In vertebrates, sex can be determined by inherited genetic factors or by the temperature experienced during embryonic development(2,3). However, the evolutionary causes of this diversity remain

Differentiation of sex chromosomes and karyotypic evolution in the eye-lid geckos (Squamata: Gekkota: Eublepharidae), a group with different modes of sex determination.

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Pokorná, Martina; Rábová, Marie; Ráb, Petr; Ferguson-Smith, Malcolm A; Rens, Willem; Kratochvíl, Lukáš

2010-11-01

The eyelid geckos (family Eublepharidae) include both species with temperature-dependent sex determination and species where genotypic sex determination (GSD) was suggested based on the observation of equal sex ratios at several incubation temperatures. In this study, we present data on karyotypes and chromosomal characteristics in 12 species (Aeluroscalabotes felinus, Coleonyx brevis, Coleonyx elegans, Coleonyx variegatus, Eublepharis angramainyu, Eublepharis macularius, Goniurosaurus araneus, Goniurosaurus lichtenfelderi, Goniurosaurus luii, Goniurosaurus splendens, Hemitheconyx caudicinctus, and Holodactylus africanus) covering all genera of the family, and search for the presence of heteromorphic sex chromosomes. Phylogenetic mapping of chromosomal changes showed a long evolutionary stasis of karyotypes with all acrocentric chromosomes followed by numerous chromosomal rearrangements in the ancestors of two lineages. We have found heteromorphic sex chromosomes in only one species, which suggests that sex chromosomes in most GSD species of the eyelid geckos are not morphologically differentiated. The sexual difference in karyotype was detected only in C. elegans which has a multiple sex chromosome system (X(1)X(2)Y). The metacentric Y chromosome evolved most likely via centric fusion of two acrocentric chromosomes involving loss of interstitial telomeric sequences. We conclude that the eyelid geckos exhibit diversity in sex determination ranging from the absence of any sexual differences to heteromorphic sex chromosomes, which makes them an interesting system for exploring the evolutionary origin of sexually dimorphic genomes.

Expression of putative sex-determining genes during the thermosensitive period of gonad development in the snapping turtle, Chelydra serpentina.

Science.gov (United States)

Rhen, T; Metzger, K; Schroeder, A; Woodward, R

2007-01-01

Modes of sex determination are quite variable in vertebrates. The developmental decision to form a testis or an ovary can be influenced by one gene, several genes, environmental variables, or a combination of these factors. Nevertheless, certain morphogenetic aspects of sex determination appear to be conserved in amniotes. Here we clone fragments of nine candidate sex-determining genes from the snapping turtle Chelydra serpentina, a species with temperature-dependent sex determination (TSD). We then analyze expression of these genes during the thermosensitive period of gonad development. In particular, we compare gene expression profiles in gonads from embryos incubated at a male-producing temperature to those from embryos at a female-producing temperature. Expression of Dmrt1 and Sox9 mRNA increased gradually at the male-producing temperature, but was suppressed at the female-producing temperature. This finding suggests that Dmrt1 and Sox9 play a role in testis development. In contrast, expression of aromatase, androgen receptor (Ar), and Foxl2 mRNA was constant at the male-producing temperature, but increased several-fold in embryos at the female-producing temperature. Aromatase, Ar, and Foxl2 may therefore play a role in ovary development. In addition, there was a small temperature effect on ER alpha expression with lower mRNA levels found in embryos at the female-producing temperature. Finally, Dax1, Fgf9, and SF-1 were not differentially expressed during the sex-determining period, suggesting these genes are not involved in sex determination in the snapping turtle. Comparison of gene expression profiles among amniotes indicates that Dmrt1 and Sox9 are part of a core testis-determining pathway and that Ar, aromatase, ER alpha, and Foxl2 are part of a core ovary-determining pathway. 2007 S. Karger AG, Basel

Phylogeny determines flower size-dependent sex allocation at flowering in a hermaphroditic family.

Science.gov (United States)

Teixido, A L; Guzmán, B; Staggemeier, V G; Valladares, F

2017-11-01

In animal-pollinated hermaphroditic plants, optimal floral allocation determines relative investment into sexes, which is ultimately dependent on flower size. Larger flowers disproportionally increase maleness whereas smaller and less rewarding flowers favour female function. Although floral traits are considered strongly conserved, phylogenetic relationships in the interspecific patterns of resource allocation to floral sex remain overlooked. We investigated these patterns in Cistaceae, a hermaphroditic family. We reconstructed phylogenetic relationships among Cistaceae species and quantified phylogenetic signal for flower size, dry mass and nutrient allocation to floral structures in 23 Mediterranean species using Blomberg's K-statistic. Lastly, phylogenetically-controlled correlational and regression analyses were applied to examine flower size-based allometry in resource allocation to floral structures. Sepals received the highest dry mass allocation, followed by petals, whereas sexual structures increased nutrient allocation. Flower size and resource allocation to floral structures, except for carpels, showed a strong phylogenetic signal. Larger-flowered species allometrically allocated more resources to maleness, by increasing allocation to corollas and stamens. Our results suggest a major role of phylogeny in determining interspecific changes in flower size and subsequent floral sex allocation. This implies that flower size balances the male-female function over the evolutionary history of Cistaceae. While allometric resource investment in maleness is inherited across species diversification, allocation to the female function seems a labile trait that varies among closely related species that have diversified into different ecological niches. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

Maintenance of polygenic sex determination in a fluctuating environment: an individual-based model.

Science.gov (United States)

Bateman, A W; Anholt, B R

2017-05-01

R. A. Fisher predicted that individuals should invest equally in offspring of both sexes, and that the proportion of males and females produced (the primary sex ratio) should evolve towards 1:1 when unconstrained. For many species, sex determination is dependent on sex chromosomes, creating a strong tendency for balanced sex ratios, but in other cases, multiple autosomal genes interact to determine sex. In such cases, the maintenance of multiple sex-determining alleles at multiple loci and the consequent among-family variability in sex ratios presents a puzzle, as theory predicts that such systems should be unstable. Theory also predicts that environmental influences on sex can complicate outcomes of genetic sex determination, and that population structure may play a role. Tigriopus californicus, a copepod that lives in splash-pool metapopulations and exhibits polygenic and environment-dependent sex determination, presents a test case for relevant theory. We use this species as a model for parameterizing an individual-based simulation to investigate conditions that could maintain polygenic sex determination. We find that metapopulation structure can delay the degradation of polygenic sex determination and that periods of alternating frequency-dependent selection, imposed by seasonal fluctuations in environmental conditions, can maintain polygenic sex determination indefinitely. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Sex determination

Indian Academy of Sciences (India)

The sex-determining system differs considerably among organisms. Even among insect species, the genetic system for sex-determination is highly diversified. In Drosophila melanogaster, somatic sexual differentiation is regulated by a well characterized genetic hierarchy X : A > Sxl > tra/tra2 > dsx and fru. This cascade ...

Effect of exogenous estradiol applied at different embryonic stages on sex determination, growth, and mortality in the leopard gecko (Eublepharis macularius).

Science.gov (United States)

Tousignant, A; Crews, D

1994-01-01

Temperature-dependent sex determination (TSD) occurs in three orders of reptiles. Several studies have examined the ability of estradiol to produce female hatchlings incubated at a male-producing temperature. The results of these experiments support the idea that estradiol could be used as a powerful tool in the conservation of endangered species with TSD by manipulating hatchling sex ratios. However, these experiments have concentrated on the mechanism of determination. This experiment was designed to test the efficacy of various dosages of estradiol applied at two different stages to alter the hatchling sex ratio as well as determining the potential use of such manipulation for conservation efforts by monitoring egg mortality and hatchling growth. The leopard gecko (Eublepharis macularius) exhibits TSD and reaches reproductive maturity in less than one year, making it an excellent model for evaluating the long-term effects of estradiol. The results demonstrate that estradiol has a dose-dependent effect on the hatchling sex ratio while only high dosages applied at the later stage of development showed increased mortality. Estrogen-determined females grew at the same rate as temperature-determined females and have produced viable hatchlings. Estradiol treatment of eggs from endangered species may provide a method of insuring female offspring when the TSD pattern is unknown or equipment for controlled incubation is unavailable.

Sex determination mode does not affect body or genital development of the central bearded dragon (Pogona vitticeps

Directory of Open Access Journals (Sweden)

Sarah L. Whiteley

2017-12-01

Full Text Available Abstract Background The development of male- or female-specific phenotypes in squamates is typically controlled by either temperature-dependent sex determination (TSD or chromosome-based genetic sex determination (GSD. However, while sex determination is a major switch in individual phenotypic development, it is unknownhow evolutionary transitions between GSD and TSD might impact on the evolution of squamate phenotypes, particularly the fast-evolving and diverse genitalia. Here, we take the unique opportunity of studying the impact of both sex determination mechanisms on the embryological development of the central bearded dragon (Pogona vitticeps. This is possible because of the transitional sex determination system of this species, in which genetically male individuals reverse sex at high incubation temperatures. This can trigger the evolutionary transition of GSD to TSD in a single generation, making P. vitticeps an ideal model organism for comparing the effects of both sex determination processes in the same species. Results We conducted four incubation experiments on 265 P. vitticeps eggs, covering two temperature regimes (“normal” at 28 °C and “sex reversing” at 36 °C and the two maternal sexual genotypes (concordant ZW females or sex-reversed ZZ females. From this, we provide the first detailed staging system for the species, with a focus on genital and limb development. This was augmented by a new sex chromosome identification methodology for P. vitticeps that is non-destructive to the embryo. We found a strong correlation between embryo age and embryo stage. Aside from faster growth in 36 °C treatments, body and external genital development was entirely unperturbed by temperature, sex reversal or maternal sexual genotype. Unexpectedly, all females developed hemipenes (the genital phenotype of adult male P. vitticeps, which regress close to hatching. Conclusions The tight correlation between embryo age and embryo stage

Altering the sex determination pathway in Drosophila fat body modifies sex-specific stress responses.

Science.gov (United States)

Argue, Kathryn J; Neckameyer, Wendi S

2014-07-01

The stress response in Drosophila melanogaster reveals sex differences in behavior, similar to what has been observed in mammals. However, unlike mammals, the sex determination pathway in Drosophila is well established, making this an ideal system to identify factors involved in the modulation of sex-specific responses to stress. In this study, we show that the Drosophila fat body, which has been shown to be important for energy homeostasis and sex determination, is a dynamic tissue that is altered in response to stress in a sex and time-dependent manner. We manipulated the sex determination pathway in the fat body via targeted expression of transformer and transformer-2 and analyzed these animals for changes in their response to stress. In the majority of cases, manipulation of transformer or transformer-2 was able to change the physiological output in response to starvation and oxidative stress to that of the opposite sex. Our data also uncover the possibility of additional downstream targets for transformer and transformer-2 that are separate from the sex determination pathway and can influence behavioral and physiological responses. Copyright © 2014 the American Physiological Society.

Karyotype analysis and sex determination in Australian Brush-turkeys (Alectura lathami.

Directory of Open Access Journals (Sweden)

Madison T Ortega

Full Text Available Sexual differentiation across taxa may be due to genetic sex determination (GSD and/or temperature sex determination (TSD. In many mammals, males are heterogametic (XY; whereas females are homogametic (XX. In most birds, the opposite is the case with females being heterogametic (ZW and males the homogametic sex (ZZ. Many reptile species lack sex chromosomes, and instead, sexual differentiation is influenced by temperature with specific temperatures promoting males or females varying across species possessing this form of sexual differentiation, although TSD has recently been shown to override GSD in Australian central beaded dragons (Pogona vitticeps. There has been speculation that Australian Brush-turkeys (Alectura lathami exhibit TSD alone and/or in combination with GSD. Thus, we sought to determine if this species possesses sex chromosomes. Blood was collected from one sexually mature female and two sexually mature males residing at Sylvan Heights Bird Park (SHBP and shipped for karyotype analysis. Karyotype analysis revealed that contrary to speculation, Australian Brush-turkeys possess the classic avian ZW/ZZ sex chromosomes. It remains a possibility that a biased primary sex ratio of Australian Brush-turkeys might be influenced by maternal condition prior to ovulation that result in her laying predominantly Z- or W-bearing eggs and/or sex-biased mortality due to higher sensitivity of one sex in environmental conditions. A better understanding of how maternal and extrinsic factors might differentially modulate ovulation of Z- or W-bearing eggs and hatching of developing chicks possessing ZW or ZZ sex chromosomes could be essential in conservation strategies used to save endangered members of Megapodiidae.

The evolution of sex ratios and sex-determining systems

NARCIS (Netherlands)

Uller, Tobias; Pen, Ido; Wapstra, Erik; Beukeboom, Leo W.; Komdeur, Jan

Sex determination is a fundamental process governed by diverse mechanisms. Sex ratio selection is commonly implicated in the evolution of sex-determining systems, although formal models are rare. Here, we argue that, although sex ratio selection can induce shifts in sex determination, genomic

What was the ancestral sex-determining mechanism in amniote vertebrates?

Science.gov (United States)

Johnson Pokorná, Martina; Kratochvíl, Lukáš

2016-02-01

Amniote vertebrates, the group consisting of mammals and reptiles including birds, possess various mechanisms of sex determination. Under environmental sex determination (ESD), the sex of individuals depends on the environmental conditions occurring during their development and therefore there are no sexual differences present in their genotypes. Alternatively, through the mode of genotypic sex determination (GSD), sex is determined by a sex-specific genotype, i.e. by the combination of sex chromosomes at various stages of differentiation at conception. As well as influencing sex determination, sex-specific parts of genomes may, and often do, develop specific reproductive or ecological roles in their bearers. Accordingly, an individual with a mismatch between phenotypic (gonadal) and genotypic sex, for example an individual sex-reversed by environmental effects, should have a lower fitness due to the lack of specialized, sex-specific parts of their genome. In this case, evolutionary transitions from GSD to ESD should be less likely than transitions in the opposite direction. This prediction contrasts with the view that GSD was the ancestral sex-determining mechanism for amniote vertebrates. Ancestral GSD would require several transitions from GSD to ESD associated with an independent dedifferentiation of sex chromosomes, at least in the ancestors of crocodiles, turtles, and lepidosaurs (tuataras and squamate reptiles). In this review, we argue that the alternative theory postulating ESD as ancestral in amniotes is more parsimonious and is largely concordant with the theoretical expectations and current knowledge of the phylogenetic distribution and homology of sex-determining mechanisms. © 2014 Cambridge Philosophical Society.

Complementary sex determination in the parasitic wasp Diachasmimorpha longicaudata.

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Leonela Carabajal Paladino

Full Text Available We studied the sex determination in Diachasmimorpha longicaudata, a parasitoid braconid wasp widely used as biological control agent of fruit pest tephritid flies. We tested the complementary sex determination hypothesis (CSD known in at least 60 species of Hymenoptera. According to CSD, male or female development depends on the allelic composition of one sex locus (single-locus CSD or multiple sex loci (multiple-locus CSD. Hemizygote individuals are normal haploid males, and heterozygotes for at least one sex locus are normal diploid females, but homozygotes for all the sex loci are diploid males. In order to force the occurrence of diploid males in D. longicaudata, we established highly inbred lines and examined their offspring using chromosome counting, flow cytometry, and sex ratio analysis. We found that when mother-son crosses were studied, this wasp produced about 20% of diploid males out of the total male progeny. Our results suggest that this parasitoid may represent the second genus with multiple-locus CSD in Hymenoptera. Knowledge about the sex determination system in D. longicaudata is relevant for the improvement of mass rearing protocols of this species. This information also provides the necessary background for further investigations on the underlying molecular mechanisms of sex determination in this species, and a better insight into the evolution of this pathway in Hymenoptera in particular and insects in general.

Sex selection and restricting abortion and sex determination.

Science.gov (United States)

Zilberberg, Julie

2007-11-01

Sex selection in India and China is fostered by a limiting social structure that disallows women from performing the roles that men perform, and relegates women to a lower status level. Individual parents and individual families benefit concretely from having a son born into the family, while society, and girls and women as a group, are harmed by the widespread practice of sex selection. Sex selection reinforces oppression of women and girls. Sex selection is best addressed by ameliorating the situations of women and girls, increasing their autonomy, and elevating their status in society. One might argue that restricting or prohibiting abortion, prohibiting sex selection, and prohibiting sex determination would eliminate sex selective abortion. But this decreases women's autonomy rather than increases it. Such practices will turn underground. Sex selective infanticide, and slower death by long term neglect, could increase. If abortion is restricted, the burden is placed on women seeking abortions to show that they have a legally acceptable or legitimate reason for a desired abortion, and this seriously limits women's autonomy. Instead of restricting abortion, banning sex selection, and sex determination, it is better to address the practice of sex selection by elevating the status of women and empowering women so that giving birth to a girl is a real and positive option, instead of a detriment to the parents and family as it is currently. But, if a ban on sex selective abortion or a ban on sex determination is indeed instituted, then wider social change promoting women's status in society should be instituted simultaneously.

Temperature dependence of the cosphi conductance in Josephson tunnel junctions determined from plasma resonance experiments

DEFF Research Database (Denmark)

Pedersen, Niels Falsig; Sørensen, O. H.; Mygind, Jesper

1978-01-01

The microwave response at 9 GHz of Sn-O-Sn tunnel-junction current biased at zero dc voltage has been measured just below the critical temperature Tc of the Sn films. The temperature dependence of the cosφ conductance is determined from the resonant response at the junction plasma frequency fp...

The behavioural consequences of sex reversal in dragons

Science.gov (United States)

Li, Hong; Holleley, Clare E.; Elphick, Melanie; Georges, Arthur

2016-01-01

Sex differences in morphology, physiology, and behaviour are caused by sex-linked genes, as well as by circulating sex-steroid levels. Thus, a shift from genotypic to environmental sex determination may create an organism that exhibits a mixture of male-like and female-like traits. We studied a lizard species (Central Bearded Dragon, Pogona vitticeps), in which the high-temperature incubation of eggs transforms genetically male individuals into functional females. Although they are reproductively female, sex-reversed dragons (individuals with ZZ genotype reversed to female phenotype) resemble genetic males rather than females in morphology (relative tail length), general behaviour (boldness and activity level), and thermoregulatory tactics. Indeed, sex-reversed ‘females’ are more male-like in some behavioural traits than are genetic males. This novel phenotype may impose strong selection on the frequency of sex reversal within natural populations, facilitating rapid shifts in sex-determining systems. A single period of high incubation temperatures (generating thermally induced sex reversal) can produce functionally female individuals with male-like (or novel) traits that enhance individual fitness, allowing the new temperature-dependent sex-determining system to rapidly replace the previous genetically based one.

Sex Determination, Sex Chromosomes, and Karyotype Evolution in Insects.

Science.gov (United States)

Blackmon, Heath; Ross, Laura; Bachtrog, Doris

2017-01-01

Insects harbor a tremendous diversity of sex determining mechanisms both within and between groups. For example, in some orders such as Hymenoptera, all members are haplodiploid, whereas Diptera contain species with homomorphic as well as male and female heterogametic sex chromosome systems or paternal genome elimination. We have established a large database on karyotypes and sex chromosomes in insects, containing information on over 13000 species covering 29 orders of insects. This database constitutes a unique starting point to report phylogenetic patterns on the distribution of sex determination mechanisms, sex chromosomes, and karyotypes among insects and allows us to test general theories on the evolutionary dynamics of karyotypes, sex chromosomes, and sex determination systems in a comparative framework. Phylogenetic analysis reveals that male heterogamety is the ancestral mode of sex determination in insects, and transitions to female heterogamety are extremely rare. Many insect orders harbor species with complex sex chromosomes, and gains and losses of the sex-limited chromosome are frequent in some groups. Haplodiploidy originated several times within insects, and parthenogenesis is rare but evolves frequently. Providing a single source to electronically access data previously distributed among more than 500 articles and books will not only accelerate analyses of the assembled data, but also provide a unique resource to guide research on which taxa are likely to be informative to address specific questions, for example, for genome sequencing projects or large-scale comparative studies. © The American Genetic Association 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Correlation between temperature dependence of elastic moduli and Debye temperature of paramagnetic metal

International Nuclear Information System (INIS)

Bodryakov, V.Yu.; Povzner, A.A.

2000-01-01

The correlation between the temperature dependence of elastic moduli and the Debye temperature of paramagnetic metal is analyzed in neglect of the temperature dependence of the Poison coefficient σ within the frames of the Debye-Grueneisen presentations. It is shown, that namely the temperature dependence of the elastic moduli determines primarily the temperature dependence of the Debye temperature Θ(T). On the other hand, the temperature dependence Θ(T) very weakly effects the temperature dependence of the elastic moduli. The later made it possible to formulate the self-consistent approach to calculation of the elastic moduli temperature dependence. The numerical estimates of this dependence parameters are conducted by the example of the all around compression modulus of the paramagnetic lutetium [ru

Temperature dependence of the calibration factor of radon and radium determination in water samples by SSNTD

CERN Document Server

Hunyadi, I; Hakl, J; Baradacs, E; Dezso, Z

1999-01-01

The sensitivity of a sup 2 sup 2 sup 6 Ra determination method of water samples by SSNTD was measured as a function of storage temperature during exposure. The method is based on an etched track type radon monitor, which is closed into a gas permeable foil and is immersed in the water sample. The sample is sealed in a glass vessel and stored for an exposure time of 10-30 days. The sensitivity increased more than a factor of two when the storage temperature was raised from 2 deg. C to 30 deg. C. Temperature dependence of the partition coefficient of radon between water and air provides explanation for this dependence. For practical radio- analytical application the temperature dependence of the calibration factor is given by fitting the sensitivity data obtained by measuring sup 2 sup 2 sup 6 Ra standard solutions (in the activity concentration range of 0.1-48.5 kBq m sup - sup 3) at different storage temperatures.

Birth order, individual sex and sex of competitors determine the outcome of conflict among siblings over parental care

Science.gov (United States)

Bonisoli-Alquati, Andrea; Boncoraglio, Giuseppe; Caprioli, Manuela; Saino, Nicola

2011-01-01

Success in competition for limiting parental resources depends on the interplay between parental decisions over allocation of care and offspring traits. Birth order, individual sex and sex of competing siblings are major candidates as determinants of success in sib–sib competition, but experimental studies focusing on the combined effect of these factors on parent–offspring communication and within-brood competitive dynamics are rare. Here, we assessed individual food intake and body mass gain during feeding trials in barn swallow chicks differing for seniority and sex, and compared the intensity of their acoustic and postural solicitation (begging) displays. Begging intensity and success in competition depended on seniority in combination with individual sex and sex of the opponent. Junior chicks begged more than seniors, independently of satiation level (which was also experimentally manipulated), and obtained greater access to food. Females were generally weaker competitors than males. Individual sex and sex of the opponent also affected duration of begging bouts. Present results thus show that competition with siblings can make the rearing environment variably harsh for developing chicks, depending on individual sex, sex of competing broodmates and age ranking within the nest. They also suggest that parental decisions on the allocation of care and response of kin to signalling siblings may further contribute to the outcome of sibling competition. PMID:20943688

Determining Role of the Chain Mechanism in the Temperature Dependence of the Gas-Phase Rate of Combustion Reactions

Science.gov (United States)

Azatyan, V. V.; Bolod'yan, I. A.; Kopylov, N. P.; Kopylov, S. N.; Prokopenko, V. M.; Shebeko, Yu. N.

2018-05-01

It is shown that the strong dependence of the rate of gas-phase combustion reactions on temperature is determined by the high values of the reaction rate constants of free atoms and radicals. It is established that with a branched chain mechanism, a special role in the reaction rate temperature dependence is played by positive feedback between the concentrations of active intermediate species and the rate of their change. The role of the chemical mechanism in the temperature dependence of the process rate with and without inhibitors is considered.

Temperature dependence of plastic scintillators

Science.gov (United States)

Peralta, L.

2018-03-01

Plastic scintillator detectors have been studied as dosimeters, since they provide a cost-effective alternative to conventional ionization chambers. Several articles have reported undesired response dependencies on beam energy and temperature, which provides the motivation to determine appropriate correction factors. In this work, we studied the light yield temperature dependency of four plastic scintillators, BCF-10, BCF-60, BC-404, RP-200A and two clear fibers, BCF-98 and SK-80. Measurements were made using a 50 kVp X-ray beam to produce the scintillation and/or radioluminescence signal. The 0 to 40 °C temperature range was scanned for each scintillator, and temperature coefficients were obtained.

Quantification of three steroid hormone receptors of the leopard gecko (Eublepharis macularius), a lizard with temperature-dependent sex determination: their tissue distributions and the effect of environmental change on their expressions.

Science.gov (United States)

Endo, Daisuke; Park, Min Kyun

2003-12-01

Sex steroid hormones play a central role in the reproduction of all vertebrates. These hormones function through their specific receptors, so the expression levels of the receptors may reflect the responsibility of target organs. However, there was no effective method to quantify the expression levels of these receptors in reptilian species. In this study, we established the competitive-PCR assay systems for the quantification of the mRNA expression levels of three sex steroid hormone receptors in the leopard gecko. These assay systems were successfully able to detect the mRNA expression level of each receptor in various organs of male adult leopard geckoes. The expression levels of mRNA of these receptors were highly various depending on the organs assayed. This is the first report regarding the tissue distributions of sex steroid hormone receptor expressions in reptile. The effects of environmental conditions on these hormone receptor expressions were also examined. After the low temperature and short photoperiod treatment for 6 weeks, only the androgen receptor expression was significantly increased in the testes. The competitive-PCR assay systems established in this report should be applicable for various studies of the molecular mechanism underlying the reproductive activity of the leopard gecko.

Determination of the temperature dependence of tungsten erosion

International Nuclear Information System (INIS)

Maier, H.; Greuner, H.; Toussaint, U. von; Balden, M.; Böswirth, B.; Elgeti, S.

2015-01-01

We present the results of erosion measurements on actively cooled tungsten samples at quasi-constant surface temperature conditions performed in the high heat flux facility GLADIS. The samples were exposed to a H beam at a central power density of 10 MW/m 2 up to a fluence of 10 26 m −2 . We observe a weak temperature dependence of the erosion yield. The data are compared with similar data obtained from loading with a H beam with He admixture. Both datasets are analysed in a probabilistic approach. We obtain activation energies of 0.04 eV and 0.06 eV for the cases with and without He, respectively

Jealousy, Gender, Sex Roles, and Dependency.

Science.gov (United States)

Madden, Margaret E.; And Others

One hundred adults ages 18 to 42 completed measures of jealousy and dependency in romantic relationships and of sex role traditionalism. Traditionalism and jealousy were correlated, as predicted, but dependency and jealousy were not. For men, but not for women, traditionalism and jealousy were positively correlated. Dependency and traditionalism…

Experimental determination of the temperature dependence of metallic work functions at low temperatures. Progress report

International Nuclear Information System (INIS)

Pipes, P.B.

1977-01-01

Progress made under ERDA Contract No. EY-76-S-02-2314.002 is described. Efforts to gain theoretical insight into the temperature dependence of the contact potential of Nb near the superconducting transition have only been qualitatively successful. Preliminary measurements of adsorbed 4 He gas on the temperature dependence of the contact potentials of metals were performed and compared with a previously developed theory

Effect of Temperature on Reproduction and Sex Ratio of Guppy (Poecilia reticulata Peters)

OpenAIRE

H. Arfah; S. Mariam; . Alimuddin

2007-01-01

Water temperature could affect the reproduction of broodstock and sex ratio of progeny.  In this study, broodstock of guppy (Poecilia reticulata Peters) was reared in different temperature to determine its effect on reproduction of broodstock and sex ratio of their progeny. The result of study show that broodstock reared at 27°C produced more fry (16 males mean) than that of 30°C (10 males), while broodstock reared at 33°C produced no progeny.  Percentage of male fish produced by broodstock r...

The Interplay Between Fat Mass and Fat Distribution as Determinants of the Metabolic Syndrome Is Sex-Dependent.

Science.gov (United States)

Lind, Lars; Ärnlöv, Johan; Lampa, Erik

2017-09-01

Fat mass and fat distribution are major determinants of the metabolic syndrome (MetS), but the interplay between them has not been thoroughly investigated. In addition, fat mass and fat distribution are generally different in men than in women. We aimed to determine whether the interplay between fat mass and fat distribution regarding MetS and its components is sex-dependent using data from the large-scale population-based sample EpiHealth. Occurrence of MetS and its components was determined together with fat mass by bioimpedance in 19,094 participants in the EpiHealth sample [mean age 61 years (SD 8.5), 56% females]. MetS was defined by the NCEP/ATPIII-criteria. MetS prevalence was 23.0%. Fat mass (percent of body weight) was more strongly related to MetS (and the number of MetS components) in men than in women (P distribution on the fat mass versus MetS-relationship is stronger in women.

Fish with thermolabile sex determination (TSD) as models to study brain sex differentiation.

Science.gov (United States)

Blázquez, Mercedes; Somoza, Gustavo M

2010-05-01

As fish are ectothermic animals, water temperature can affect their basic biological processes such as larval development, growth and reproduction. Similar to reptiles, the incubation temperature during early phases of development is capable to modify sex ratios in a large number of fish species. This phenomenon, known as thermolabile sex determination (TSD) was first reported in Menidia menidia, a species belonging to the family Atherinopsidae. Since then, an increasing number of fish have also been found to exhibit TSD. Traditionally, likewise in reptiles, several TSD patterns have been described in fish, however it has been recently postulated that only one, females at low temperatures and males at high temperatures, may represent the "real" or "true" TSD. Many studies regarding the influence of temperature on the final sex ratios have been focused on the expression and activity of gonadal aromatase, the enzyme involved in the conversion of androgens into estrogens and encoded by the cyp19a1a gene. In this regard, teleost fish, may be due to a whole genome duplication event, produce another aromatase enzyme, commonly named brain aromatase, encoded by the cyp19a1b gene. Contrary to what has been described in other vertebrates, fish exhibit very high levels of aromatase activity in the brain and therefore they synthesize high amounts of neuroestrogens. However, its biological significance is still not understood. In addition, the mechanism whereby temperature can induce the development of a testis or an ovary still remains elusive. In this context the present review is aimed to discuss several theories about the possible role of brain aromatase using fish as models. The relevance of brain aromatase and therefore of neuroestrogens as the possible cue for gonadal differentiation is raised. In addition, the possible role of brain aromatase as the way to keep the high levels of neurogenesis in fish is also considered. Several key examples of how teleosts and aromatase

The Endocannabinoid System and Sex Steroid Hormone-Dependent Cancers

Directory of Open Access Journals (Sweden)

Thangesweran Ayakannu

2013-01-01

Full Text Available The “endocannabinoid system (ECS” comprises the endocannabinoids, the enzymes that regulate their synthesis and degradation, the prototypical cannabinoid receptors (CB1 and CB2, some noncannabinoid receptors, and an, as yet, uncharacterised transport system. Recent evidence suggests that both cannabinoid receptors are present in sex steroid hormone-dependent cancer tissues and potentially play an important role in those malignancies. Sex steroid hormones regulate the endocannabinoid system and the endocannabinoids prevent tumour development through putative protective mechanisms that prevent cell growth and migration, suggesting an important role for endocannabinoids in the regulation of sex hormone-dependent tumours and metastasis. Here, the role of the endocannabinoid system in sex steroid hormone-dependent cancers is described and the potential for novel therapies assessed.

Vertebrate sex-determining genes play musical chairs.

Science.gov (United States)

Pan, Qiaowei; Anderson, Jennifer; Bertho, Sylvain; Herpin, Amaury; Wilson, Catherine; Postlethwait, John H; Schartl, Manfred; Guiguen, Yann

2016-01-01

Sexual reproduction is one of the most highly conserved processes in evolution. However, the genetic and cellular mechanisms making the decision of whether the undifferentiated gonad of animal embryos develops either towards male or female are manifold and quite diverse. In vertebrates, sex-determining mechanisms range from environmental to simple or complex genetic mechanisms and different mechanisms have evolved repeatedly and independently. In species with simple genetic sex-determination, master sex-determining genes lying on sex chromosomes drive the gonadal differentiation process by switching on a developmental program, which ultimately leads to testicular or ovarian differentiation. So far, very few sex-determining genes have been identified in vertebrates and apart from mammals and birds, these genes are apparently not conserved over a larger number of related orders, families, genera, or even species. To fill this knowledge gap and to better explore genetic sex-determination, we propose a strategy (RAD-Sex) that makes use of next-generation sequencing technology to identify genetic markers that define sex-specific segments of the male or female genome. Copyright © 2016 Académie des sciences. All rights reserved.

Sex-determination systems and their evolution: Mammals

International Nuclear Information System (INIS)

Colorado Garzon, Fredy A; Matta Camacho, Nubia E; Sanchez, Antonio

2012-01-01

Sex-determination methods are very diverse as they have become an enduring research field, understanding the causes of gonadal development and elucidating the main factors involved in sex-determination of offspring required relating information from far-ranging areas such as cytology, embryology, morphology, molecular biology and even ecology and evolution. This article presents an overview of sex-determination in placental mammals, encompassing several levels of biological organization. The importance of the underlying molecular tools in the context of sex-determination assays and their implications in conservation genetics is also discussed.

Did Lizards Follow Unique Pathways in Sex Chromosome Evolution?

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Gleeson, Dianne; Georges, Arthur

2018-01-01

Reptiles show remarkable diversity in modes of reproduction and sex determination, including high variation in the morphology of sex chromosomes, ranging from homomorphic to highly heteromorphic. Additionally, the co-existence of genotypic sex determination (GSD) and temperature-dependent sex determination (TSD) within and among sister clades makes this group an attractive model to study and understand the evolution of sex chromosomes. This is particularly so with Lizards (Order Squamata) which, among reptiles, show extraordinary morphological diversity. They also show no particular pattern of sex chromosome degeneration of the kind observed in mammals, birds and or even in snakes. We therefore speculate that sex determination sensu sex chromosome evolution is labile and rapid and largely follows independent trajectories within lizards. Here, we review the current knowledge on the evolution of sex chromosomes in lizards and discuss how sex chromosome evolution within that group differs from other amniote taxa, facilitating unique evolutionary pathways. PMID:29751579

Did Lizards Follow Unique Pathways in Sex Chromosome Evolution?

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Shayer Mahmood Ibney Alam

2018-05-01

Full Text Available Reptiles show remarkable diversity in modes of reproduction and sex determination, including high variation in the morphology of sex chromosomes, ranging from homomorphic to highly heteromorphic. Additionally, the co-existence of genotypic sex determination (GSD and temperature-dependent sex determination (TSD within and among sister clades makes this group an attractive model to study and understand the evolution of sex chromosomes. This is particularly so with Lizards (Order Squamata which, among reptiles, show extraordinary morphological diversity. They also show no particular pattern of sex chromosome degeneration of the kind observed in mammals, birds and or even in snakes. We therefore speculate that sex determination sensu sex chromosome evolution is labile and rapid and largely follows independent trajectories within lizards. Here, we review the current knowledge on the evolution of sex chromosomes in lizards and discuss how sex chromosome evolution within that group differs from other amniote taxa, facilitating unique evolutionary pathways.

Sex-specific determinants of fitness in a social mammal.

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Lardy, Sophie; Allainé, Dominique; Bonenfant, Christophe; Cohas, Aurélie

2015-11-01

Sociality should evolve when the fitness benefits of group living outweigh the costs. Theoretical models predict an optimal group size maximizing individual fitness. However, beyond the number of individuals present in a group, the characteristics of these individuals, like their sex, are likely to affect the fitness payoffs of group living. Using 20 years of individually based data on a social mammal, the Alpine marmot (Marmota marmota), we tested for the occurrence of an optimal group size and composition, and for sex-specific effects of group characteristics on fitness. Based on lifetime data of 52 males and 39 females, our findings support the existence of an optimal group size maximizing male fitness and an optimal group composition maximizing fitness of males and females. Additionally, although group characteristics (i.e., size, composition and instability) affecting male and female fitness differed, fitness depended strongly on the number of same-sex subordinates within the social group in the two sexes. By comparing multiple measures of social group characteristics and of fitness in both sexes, we highlighted the sex-specific determinants of fitness in the two sexes and revealed the crucial role of intrasexual competition in shaping social group composition.

Sex-Dependent Gene Expression in Human Pluripotent Stem Cells

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Daniel Ronen

2014-08-01

Full Text Available Males and females have a variety of sexually dimorphic traits, most of which result from hormonal differences. However, differences between male and female embryos initiate very early in development, before hormonal influence begins, suggesting the presence of genetically driven sexual dimorphisms. By comparing the gene expression profiles of male and X-inactivated female human pluripotent stem cells, we detected Y-chromosome-driven effects. We discovered that the sex-determining gene SRY is expressed in human male pluripotent stem cells and is induced by reprogramming. In addition, we detected more than 200 differentially expressed autosomal genes in male and female embryonic stem cells. Some of these genes are involved in steroid metabolism pathways and lead to sex-dependent differentiation in response to the estrogen precursor estrone. Thus, we propose that the presence of the Y chromosome and specifically SRY may drive sex-specific differences in the growth and differentiation of pluripotent stem cells.

Determination of temperature dependence of full matrix material constants of PZT-8 piezoceramics using only one sample.

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Zhang, Yang; Tang, Liguo; Tian, Hua; Wang, Jiyang; Cao, Wenwu; Zhang, Zhongwu

2017-08-15

Resonant ultrasound spectroscopy (RUS) was used to determine the temperature dependence of full matrix material constants of PZT-8 piezoceramics from room temperature to 100 °C. Property variations from sample to samples can be eliminated by using only one sample, so that data self-consistency can be guaranteed. The RUS measurement system error was estimated to be lower than 2.35%. The obtained full matrix material constants at different temperatures all have excellent self-consistency, which can help accurately predict device performance at high temperatures using finite element simulations.

Determination of sex by armbone dimensions.

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Aye, Victor Omakoji

2010-06-15

Sex determination is a vital part of the medico-legal system but can be difficult in cases where the body is damaged. The purpose of this study was to develop a technique for sex determination from three arm-bone dimensions (wrist circumference, arm length and arm span). This knowledge can be applied in cases of mass disaster, homicide and events such as sports. Data were collected for 95 Nigerian male students and 90 Nigerian female students using physical anthropometry. Discriminant function presented the wrist dimension as the dominant contributor in this study. Combination equations for both the wrist and arm-span dimensions correctly classified sex (male/female) with an accuracy rate of 84.9%. On cross-validation, sex was also established with the same 84.9% accuracy rate. Sex determination was higher in males. Sexual dimorphism was established in this study, although the wrist circumference was more distinct than arm span; a combination of both generated sex with an accuracy prediction rate of 84.9%. (c) 2010 Elsevier Ireland Ltd. All rights reserved.

70-kDa Heat Shock Cognate Protein hsc70 Mediates Calmodulin-dependent Nuclear Import of the Sex-determining Factor SRY*

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Kaur, Gurpreet; Lieu, Kim G.; Jans, David A.

2013-01-01

We recently showed that the developmentally important family of SOX (SRY (sex determining region on the Y chromosome)-related high mobility group (HMG) box) proteins require the calcium-binding protein calmodulin (CaM) for optimal nuclear accumulation, with clinical mutations in SRY that specifically impair nuclear accumulation via this pathway resulting in XY sex reversal. However, the mechanism by which CaM facilitates nuclear accumulation is unknown. Here, we show, for the first time, that the 70-kDa heat shock cognate protein hsc70 plays a key role in CaM-dependent nuclear import of SRY. Using a reconstituted nuclear import assay, we show that antibodies to hsc70 significantly reduce nuclear accumulation of wild type SRY and mutant derivatives thereof that retain CaM-dependent nuclear import, with an increased rate of nuclear accumulation upon addition of both CaM and hsc70, in contrast to an SRY mutant derivative with impaired CaM binding. siRNA knockdown of hsc70 in intact cells showed similar results, indicating clear dependence upon hsc70 for CaM-dependent nuclear import. Analysis using the technique of fluorescence recovery after photobleaching indicated that hsc70 is required for the maximal rate of SRY nuclear import in living cells but has no impact upon SRY nuclear retention/nuclear dynamics. Finally, we demonstrate direct binding of hsc70 to the SRY·CaM complex, with immunoprecipitation experiments from cell extracts showing association of hsc70 with wild type SRY, but not with a mutant derivative with impaired CaM binding, dependent on Ca2+. Our novel findings strongly implicate hsc70 in CaM-dependent nuclear import of SRY. PMID:23235156

Self-determined to exercise? Leisure-time exercise behavior, exercise motivation, and exercise dependence in youth.

Science.gov (United States)

Symons Downs, Danielle; Savage, Jennifer S; DiNallo, Jennifer M

2013-02-01

Scant research has examined the determinants of primary exercise dependence symptoms in youth. Study purposes were to examine sex differences across leisure-time exercise behavior, motivation, and primary exercise dependence symptoms in youth and the extent to which exercise behavior and motivation predicted exercise dependence within the Self-Determination Theory framework. Adolescents (N = 805; mean age = 15 years; 46% girls) completed measures of exercise behavior, motivation, and exercise dependence in health/PE classes. One-way ANOVA revealed boys scored higher than girls on leisure-time exercise behavior, exercise dependence symptoms, and most of the exercise motivation subscales. Hierarchical regression analyses indicated a) sex, exercise behavior, motivation, and their interaction terms explained 39% of the variance in primary exercise dependence; b) Integrated Regulation and Introjected Regulation were important determinants of exercise dependence; and c) sex moderated the contributions of External Regulation for predicting exercise dependence such that boys in the high and low external regulation groups had higher symptoms than girls in the high and low external regulation groups. These preliminary findings support the controlled dimensions of Integrated Regulation (boys, girls), Introjected Regulation (boys, girls), and External Regulation (boys only) are important determinants of primary exercise dependence symptoms.

Identification of the sex-determining locus in grass puffer (Takifugu niphobles) provides evidence for sex-chromosome turnover in a subset of Takifugu species

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Atsumi, Kazufumi; Kamiya, Takashi; Nozawa, Aoi; Aoki, Yuma; Tasumi, Satoshi; Koyama, Takashi; Nakamura, Osamu; Suzuki, Yuzuru

2018-01-01

There is increasing evidence for frequent turnover in sex chromosomes in vertebrates. Yet experimental systems suitable for tracing the detailed process of turnover are rare. In theory, homologous turnover is possible if the new sex-determining locus is established on the existing sex-chromosome. However, there is no empirical evidence for such an event. The genus Takifugu includes fugu (Takifugu rubripes) and its two closely-related species whose sex is most likely determined by a SNP at the Amhr2 locus. In these species, males are heterozygous, with G and C alleles at the SNP site, while females are homozygous for the C allele. To determine if a shift in the sex-determining locus occurred in another member of this genus, we used genetic mapping to characterize the sex-chromosome systems of Takifugu niphobles. We found that the G allele of Amhr2 is absent in T. niphobles. Nevertheless, our initial mapping suggests a linkage between the phenotypic sex and the chromosome 19, which harbors the Amhr2 locus. Subsequent high-resolution analysis using a sex-reversed fish demonstrated that the sex-determining locus maps to the proximal end of chromosome 19, far from the Amhr2 locus. Thus, it is likely that homologous turnover involving these species has occurred. The data also showed that there is a male-specific reduction of recombination around the sex-determining locus. Nevertheless, no evidence for sex-chromosome differentiation was detected: the reduced recombination depended on phenotypic sex rather than genotypic sex; no X- or Y-specific maker was obtained; the YY individual was viable. Furthermore, fine-scale mapping narrowed down the new sex-determining locus to the interval corresponding to approximately 300-kb of sequence in the fugu genome. Thus, T. niphobles is determined to have a young and small sex-determining region that is suitable for studying an early phase of sex-chromosome evolution and the mechanisms underlying turnover of sex chromosome. PMID

Sex Determination by Morphometry of Lips

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B. Senthil Kumar

2018-04-01

Full Text Available Background: Facial anthropometric parameters are affected by various factors including age, sex, ethnicity, socioeconomic status, environment and region. The lips become thinner as age increases and the wet line moves caudally, in addition oral commissure begins to downturn. Aim and Objectives: The purpose of this study was to create a baseline data in determining the sex of the people from India and Malaysia depending on morphometry of lips. Materials and Methods:Atotal of 100 Malaysians and 100 South Indians were enrolled for the study. Various morphometric measurements of lips were taken using Vernier caliper. The data were analyzed by one way ANOVAto find out the significance among the sex and population. Results: All the measurements of upper and lower lips were higher in males as compared to females and thus sexual dimorphism exists. Mouth width and height were found to be more in Indian males followed by Malaysian males whereas in females it's vice versa. Vermilion upper lip occupied less than half of total upper lip height, whereas vermilion lower lip occupied more than half of total lower lip height in both the population. Indian males and females differed significantly in lip parameters from those of Malaysian males and females. Conclusion: It can be concluded from the study that same standards cannot be used on each other's populations for identification and cosmetic surgery. The study highlights the applied significance of observations to forensic medicine namely, personal identification, racial and sex dimorphic criteria of identification.

Differences induced by incubation temperature, versus androgen manipulation, in male leopard geckos (Eublepharis macularius).

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Huang, Victoria; Crews, David

2012-08-20

A fundamental tenet of sexual selection is that in sexually dimorphic traits, there is variation within a sex. In leopard geckos (Eublepharis macularius), a species with temperature-dependent sex determination, embryonic temperature contributes both to sex determination and polymorphisms within each sex. In this study we report that males from different incubation temperatures, one hitherto untested, exhibit significant differences in behavior even when castrated. Further, treatment with dihydrotestosterone increases scent marking, a territorial behavior. This supports previous results indicating that temperature has a direct organizing action on brain and sociosexual behavior independent of gonadal hormones. Copyright © 2012 Elsevier Inc. All rights reserved.

Using technology, choosing sex. The campaign against sex determination and the question of choice.

Science.gov (United States)

1992-01-01

Women's groups and people's science and health groups formed the Forum Against Sex Determination and Sex Pre-Selection in November 1985 in Bombay, India, to prevent sex determination and sex preselection tests. The Forum considered sex determination and sex preselection to be an abuse of science and technology against people, especially women. Between 1901 and 1991, the sex ratio fell from 972 females/1000 males to 929/1000. The Forum saw the issue of sex determination and sex preselection as a link to oppression of and discrimination against females in all sectors of society. It also believed this to be a human rights issue. The Forum lobbied for a law regulating diagnostic techniques without banning them, since determining chromosomal abnormalities is important. The State of Maharashtra passed such a law in June 1988. It had some provisions which were counter-productive, however. For example, women undergoing a sex determination test must pay a fine of Rs 5 if found guilty of planning to terminate a pregnancy of a female fetus. Yet, neither the husband nor parents-in-law are liable, even though they often pressure women to undergo sex determination tests. The Forum's efforts and enactment of the law in Maharashtra have prompted other state governments and the central government to propose similar legislation. These state governments include Goa, Gujarat, and Orissa. The central government has met with organizations and individuals lobbying against misuse of diagnostic tests to obtain their counsel. The Forum does not feel comfortable with state control, however, since it tends to consider government to be against the people. Yet, the Forum did want the state to protect women's interests. It has raised important questions about technology, particularly concerning criteria to determine desirable and appropriate technologies.

Temperature dependence of the cosphi conductance in Josephson tunnel junctions determined from plasma resonance experiments

International Nuclear Information System (INIS)

Pedersen, N.F.; Soerensen, O.H.; Mygind, J.

1978-01-01

The microwave response at 9 GHz of Sn-O-Sn tunnel-junction current biased at zero dc voltage has been measured just below the critical temperature T/sub c/ of the Sn films. The temperature dependence of the cosphi conductance is determined from the resonant response at the junction plasma frequency f/sub p/ as the temperature is decreased from T/sub c/. We used three different schemes for observation of the plasma oscillations: (a) second-harmonic generation (excitation at approx. 4.5 GHz, f/sub p/ approx. 4.5 GHz); (b) mixing (excitations at approx. 9 and approx. 18 GHz, f/sub p/ approx. 9 GHz); (c) parametric half-harmonic oscillation (excitation at approx. 18 GHz, f/sub p/ approx. 9 GHz). Measurements were possible in two temperature intervals; 0.994 or = T/T/sub c/ > or = 0.930, with the result that as the temperature was decreased the cosphi amplitude first increased from about zero to positive values and then at lower temperatures decreased approaching -1 at the lowest temperatures of the experiment

Thermal fluctuation within nests and predicted sex ratio of Morelet's Crocodile.

Science.gov (United States)

Escobedo-Galván, Armando H; López-Luna, Marco A; Cupul-Magaña, Fabio G

2016-05-01

Understanding the interplay between thermal variations and sex ratio in reptiles with temperature-dependent sex determination is the first step for developing long-term conservation strategies. In case of crocodilians, the information is fragmentary and insufficient for establishing a general framework to consider how thermal fluctuation influence sex determination under natural conditions. The main goal of this study was to analyze thermal variation in nests of Crocodylus moreletii and to discuss the potential implications for predicting offspring sex ratio. The study was carried out at the Centro de Estudios Tecnológicos del Mar N° 2 and at the Sistemas Productivos Cocodrilo, Campeche, Mexico. Data was collected in the nesting season of Morelet's Crocodiles during three consecutive seasons (2007-2009). Thermal fluctuations for multiple areas of the nest chamber were registered by data loggers. We calculate the constant temperature equivalent based on thermal profiles among nests to assess whether there are differences between the nest temperature and its equivalent to constant temperature. We observed that mean nest temperature was only different among nests, while daily thermal fluctuations vary depending on the depth position within the nest chamber, years and nests. The constant temperature equivalent was different among and within nests, but not among survey years. We observed differences between constant temperature equivalent and mean nest temperature both at the top and in the middle of the nest cavities, but were not significantly different at the bottom of nest cavities. Our results enable examine and discuss the relevance of daily thermal fluctuations to predict sex ratio of the Morelet's Crocodile. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chromosome Banding in Amphibia. XXXVI. Multimorphic Sex Chromosomes and an Enigmatic Sex Determination in Eleutherodactylus johnstonei (Anura, Eleutherodactylidae).

Science.gov (United States)

Schmid, Michael; Steinlein, Claus

2018-01-01

A detailed cytogenetic study on the leaf litter frog Eleutherodactylus johnstonei from 14 different Caribbean islands and the mainlands of Venezuela and Guyana revealed the existence of multimorphic XY♂/XX♀ sex chromosomes 14. Their male sex determination and development depends either on the presence of 2 telocentric chromosomes 14 (XtYt), or on 1 submetacentric chromosome 14 (Xsm) plus 1 telocentric chromosome 14 (Yt), or on the presence of 2 submetacentric chromosomes 14 (XsmYsm). The female sex determination and development requires either the presence of 2 telocentric chromosomes 14 (XtXt) or 2 submetacentric chromosomes 14 (XsmXsm). In all individuals analyzed, the sex chromosomes 14 carry a prominent nucleolus organizer region in their long arms. An explanation is given for the origin of the (XtYt)♂, (XsmYt)♂, (XsmYsm)♂, (XtXt)♀, and (XsmXsm)♀ in the different populations of E. johnstonei. Furthermore, the present study gives detailed data on the chromosome banding patterns, in situ hybridization experiments, and the genome size of E. johnstonei. © 2018 S. Karger AG, Basel.

Insect sex determination: it all evolves around transformer.

Science.gov (United States)

Verhulst, Eveline C; van de Zande, Louis; Beukeboom, Leo W

2010-08-01

Insects exhibit a variety of sex determining mechanisms including male or female heterogamety and haplodiploidy. The primary signal that starts sex determination is processed by a cascade of genes ending with the conserved switch doublesex that controls sexual differentiation. Transformer is the doublesex splicing regulator and has been found in all examined insects, indicating its ancestral function as a sex-determining gene. Despite this conserved function, the variation in transformer nucleotide sequence, amino acid composition and protein structure can accommodate a multitude of upstream sex determining signals. Transformer regulation of doublesex and its taxonomic distribution indicate that the doublesex-transformer axis is conserved among all insects and that transformer is the key gene around which variation in sex determining mechanisms has evolved.

Experimental determination of the temperature-dependent penetration depth in V3Si

International Nuclear Information System (INIS)

Christen, D.K.; Kerchner, H.R.; Sekula, S.T.; Chang, Y.K.

1984-03-01

Small angle neutron diffraction from the flux-line lattice (FLL) in a high quality, single crystal of superconducting V 3 Si has been used to deduce the low-field penetration depth lambda (T). An absolute determination is possible because the FLL form factor F/sub hk/ is essentially single-valued in the scattering vector magnitude absolute value of K/sub hk/, as well as nearly London-like at low field. We obtain lambda (0) = 102 +- 1 nm, 20% to 30% larger than previous determinations of the London penetration depth lambda/sub L/ (0). The temperature dependence of lambda (T) is found to deviate from that of the BCS theory. An assessment of the data indicates the most prominent source of the discrepancy is due to strong electron-phonon coupling, and we find 2Δ(0)/k/sub B/T/sub c/ = 3.88 +- 0.07, in reasonable agreement with values found in the literature

Effects of gonadal sex and incubation temperature on the ontogeny of gonadal steroid concentrations and secondary sex structures in leopard geckos, Eublepharis macularius.

Science.gov (United States)

Rhen, Turk; Sakata, Jon T; Crews, David

2005-07-01

Incubation temperature during embryonic development determines gonadal sex in the leopard gecko (Eublepharis macularius). Incubation temperature and gonadal sex jointly influence the display of sexual and agonistic behavior in adult leopard geckos. These differences in adult behavior are organized prior to sexual maturity, and it is plausible that post-natal hormones influence neural and behavioral differentiation. Here we assessed incubation temperature and sex effects on sex steroid levels in leopard geckos at 2, 10, and 25 weeks of age and monitored the development of male secondary sex structures. Males had significantly higher androgen concentrations at all time points, whereas females had significantly higher 17beta-estradiol (E2) concentrations only at 10 and 25 weeks. Within males, age but not incubation temperature affected steroid levels and morphological development. Male androgen levels increased modestly by 10 and dramatically by 25 weeks of age, whereas E2 levels remained unchanged over this period. Most males had signs of hemipenes at 10 weeks of age, and all males had hemipenes and open preanal pores by 25 weeks of age. In females, age and incubation temperature affected E2 and dihydrotestosterone (DHT) but not T concentrations. Controlling for age, females from 34 degrees C have higher DHT and lower E2 levels than females from 30 degrees C. Further, E2 concentrations increased significantly from 2 to 10 weeks, after which E2 levels remained steady. Together, these results indicate that sexually dimorphic levels of steroids play a major role in the development of leopard gecko behavior and morphology. Furthermore, these data suggest that the organizational effects of incubation temperature on adult female phenotype could be, in part, mediated by incubation temperature effects on steroid hormone levels during juvenile development.

Individual diet has sex-dependent effects on vertebrate gut microbiota

Science.gov (United States)

Bolnick, Daniel I.; Snowberg, Lisa K.; Hirsch, Philipp E.; Lauber, Christian L.; Org, Elin; Parks, Brian; Lusis, Aldons J.; Knight, Rob; Caporaso, J. Gregory; Svanbäck, Richard

2014-01-01

Vertebrates harbour diverse communities of symbiotic gut microbes. Host diet is known to alter microbiota composition, implying that dietary treatments might alleviate diseases arising from altered microbial composition (‘dysbiosis’). However, it remains unclear whether diet effects are general or depend on host genotype. Here we show that gut microbiota composition depends on interactions between host diet and sex within populations of wild and laboratory fish, laboratory mice and humans. Within each of two natural fish populations (threespine stickleback and Eurasian perch), among-individual diet variation is correlated with individual differences in gut microbiota. However, these diet–microbiota associations are sex dependent. We document similar sex-specific diet–microbiota correlations in humans. Experimental diet manipulations in laboratory stickleback and mice confirmed that diet affects microbiota differently in males versus females. The prevalence of such genotype by environment (sex by diet) interactions implies that therapies to treat dysbiosis might have sex-specific effects. PMID:25072318

Expression of sex steroid hormone-related genes in the embryo of the leopard gecko.

Science.gov (United States)

Endo, Daisuke; Kanaho, Yoh-Ichiro; Park, Min Kyun

2008-01-01

Sex steroid hormones are known to play a central role in vertebrate sex determination and differentiation. However, the tissues in which they are produced or received during development, especially around the period of sex determination of the gonads, have rarely been investigated. In this study, we identified the cDNA sequence, including the full-length of the coding region of cholesterol side-chain cleavage enzyme (P450scc), from the leopard gecko; a lizard with temperature-dependent sex determination. Embryonic expression analysis of two steroidogenic enzymes, P450scc and P450 aromatase (P450arom), and four sex steroid hormone receptors, androgen receptor, estrogen receptor alpha and beta, and progesterone receptor, was subsequently conducted. mRNA expression of both steroidogenic enzymes was observed in the brain and gonads prior to the temperature-sensitive period of sex determination. The mRNAs of the four sex steroid hormone receptors were also detected in the brain and gonads at all stages examined. These results suggest the existence of a gonad-independent sex steroid hormone signaling system in the developing leopard gecko brain.

Determination of temperature dependency of material parameters for lead-free alkali niobate piezoceramics by the inverse method

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K. Ogo

2016-06-01

Full Text Available Sodium potassium niobate (NKN piezoceramics have been paid much attention as lead-free piezoelectric materials in high temperature devices because of their high Curie temperature. The temperature dependency of their material parameters, however, has not been determined in detail up to now. For this purpose, we exploit the so-called Inverse Method denoting a simulation-based characterization approach. Compared with other characterization methods, the Inverse Method requires only one sample shape of the piezoceramic material and has further decisive advantages. The identification of material parameters showed that NKN is mechanically softer in shear direction compared with lead zirconate titanate (PZT at room temperature. The temperature dependency of the material parameters of NKN was evaluated in the temperature range from 30 °C to 150 °C. As a result, we figured out that dielectric constants and piezoelectric constants show a monotonous and isotropic increment with increasing temperature. On the other hand, elastic stiffness constant c 44 E of NKN significantly decreased in contrast to other elastic stiffness constants. It could be revealed that the decrement of c 44 E is associated with an orthorhombic-tetragonal phase transition. Furthermore, ratio of elastic compliance constants s 44 E / s 33 E exhibited similar temperature dependent behavior to the ratio of piezoelectric constants d15/d33. It is suspected that mechanical softness in shear direction is one origin of the large piezoelectric shear mode of NKN. Our results show that NKN are suitable for high temperature devices, and that the Inverse Method should be a helpful approach to characterize material parameters under their practical operating conditions for NKN.

Age- and sex-dependent model for estimating radioiodine dose to a normal thyroid

International Nuclear Information System (INIS)

Killough, G.G.; Eckerman, K.F.

1986-01-01

This paper describes the derivation of an age- and sex-dependent model of radioiodine dosimetry in the thyroid and the application of the model to estimating the thyroid dose for each of 4215 patients who were exposed to 131 I in diagnostic and therapeutic procedures. In most cases, the available data consisted of the patient's age at the time of administration, the patient's sex, the quantity of activity administered, the clinically-determined uptake of radioiodine by the thyroid, and the time after administration at which the uptake was determined. The metabolic model is of the form A(t) = K[exp(-μ 1 t) -exp(-μ 2 t)] (μCi), where μ 1 = λ/sub r/ - λ/sub i//sup b/ (i = 1, 2), λ/sub r/ is the radiological decay-rate coefficient, and λ/sub i//sup b/ are biological removal rate coefficients. The values of λ/sub i//sup b/ are determined by solving a nonlinear equation that depends on assumptions about the time or maximum uptake an the eventual biological loss rate (through which age dependence enters). The value of K may then be calculated from knowledge of the uptakes at a particular time. The dosimetric S-factor (rad/μCi-day) is based on specific absorbed fractions for photons of energy ranging from 0.01 to 4.0 MeV for thyroid masses from 1.29 to 19.6 g; the functional form of the S-factor also involves the thyroid mass explicitly, through which the dependence on age and sex enters. An analysis of sensitivity of the model to uncertainties in the thyroid mass and the biological removal rate for several age groups is reported. 12 references, 5 figures, 5 tables

The accuracy of 2D ultrasound prenatal sex determination ...

African Journals Online (AJOL)

Most of the women were happy even when the sex differed from that which they desired. Conclusion: Prenatal sonographic sex determination has a high sensitivity index. Consequently we advocate its use prior to more invasive sex tests. Keywords: Accuracy, gender determination, prenatal gender, prenatal sex, sex ...

Sex Determination, Sex Ratios, and Genetic Conflict

NARCIS (Netherlands)

Werren, John H.; Beukeboom, Leo W.

1998-01-01

Genetic mechanisms of sex determination are unexpectedly diverse and change rapidly during evolution. We review the role of genetic conflict as the driving force behind this diversity and turnover. Genetic conflict occurs when different components of a genetic system are subject to selection in

Maternal provision of non-sex-specific transformer messenger RNA in sex determination of the wasp Asobara tabida.

Science.gov (United States)

Geuverink, E; Verhulst, E C; van Leussen, M; van de Zande, L; Beukeboom, L W

2018-02-01

In many insect species maternal provision of sex-specifically spliced messenger RNA (mRNA) of sex determination genes is an essential component of the sex determination mechanism. In haplodiploid Hymenoptera, maternal provision in combination with genomic imprinting has been shown for the parasitoid Nasonia vitripennis, known as maternal effect genomic imprinting sex determination (MEGISD). Here, we characterize the sex determination cascade of Asobara tabida, another hymenopteran parasitoid. We show the presence of the conserved sex determination genes doublesex (dsx), transformer (tra) and transformer-2 (tra2) orthologues in As. tabida. Of these, At-dsx and At-tra are sex-specifically spliced, indicating a conserved function in sex determination. At-tra and At-tra2 mRNA is maternally provided to embryos but, in contrast to most studied insects, As. tabida females transmit a non-sex-specific splice form of At-tra mRNA to the eggs. In this respect, As. tabida sex determination differs from the MEGISD mechanism. How the paternal genome can induce female development in the absence of maternal provision of sex-specifically spliced mRNA remains an open question. Our study reports a hitherto unknown variant of maternal effect sex determination and accentuates the diversity of insect sex determination mechanisms. © 2017 The Authors. Insect Molecular Biology published by John Wiley & Sons Ltd on behalf of Royal Entomological Society.

An analytical method for determining the temperature dependent moisture diffusivities of pumpkin seeds during drying process

Energy Technology Data Exchange (ETDEWEB)

Can, Ahmet [Department of Mechanical Engineering, University of Trakya, 22030 Edirne (Turkey)

2007-02-15

This paper presents an analytical method, which determines the moisture diffusion coefficients for the natural and forced convection hot air drying of pumpkin seeds and their temperature dependence. In order to obtain scientific data, the pumpkin seed drying process was investigated under both natural and forced hot air convection regimes. This paper presents the experimental results in which the drying air was heated by solar energy. (author)

[Elucidation of key genes in sex determination in genetics teaching].

Science.gov (United States)

Li, Meng; He, Zhumei

2014-06-01

Sex is an important and complex feature of organisms, which is controlled by the genetic and environmental factors. The genetic factors, i.e., genes, are vital in sex determination. However, not all the related genes play the same roles, and some key genes play a vital role in the sex determination and differentiation. With the development of the modern genetics, a great progress on the key genes has been made in sex determination. In this review, we summarize the mechanism of sex determination and the strategy of how to study the key genes in sex determination. It will help us to understand the mechanism of sex determination better in the teaching of genetics.

Sex Determination: Why So Many Ways of Doing It?

Science.gov (United States)

Bachtrog, Doris; Mank, Judith E.; Peichel, Catherine L.; Kirkpatrick, Mark; Otto, Sarah P.; Ashman, Tia-Lynn; Hahn, Matthew W.; Kitano, Jun; Mayrose, Itay; Ming, Ray; Perrin, Nicolas; Ross, Laura; Valenzuela, Nicole; Vamosi, Jana C.

2014-01-01

Sexual reproduction is an ancient feature of life on earth, and the familiar X and Y chromosomes in humans and other model species have led to the impression that sex determination mechanisms are old and conserved. In fact, males and females are determined by diverse mechanisms that evolve rapidly in many taxa. Yet this diversity in primary sex-determining signals is coupled with conserved molecular pathways that trigger male or female development. Conflicting selection on different parts of the genome and on the two sexes may drive many of these transitions, but few systems with rapid turnover of sex determination mechanisms have been rigorously studied. Here we survey our current understanding of how and why sex determination evolves in animals and plants and identify important gaps in our knowledge that present exciting research opportunities to characterize the evolutionary forces and molecular pathways underlying the evolution of sex determination. PMID:24983465

Microbial manipulation of host sex determination

NARCIS (Netherlands)

Beukeboom, Leo W.

A recent study in the lepidopteran Ostrinia scapulalis shows that endosymbionts can actively manipulate the sex determination mechanism of their host. Wolbachia bacteria alter the sex-specific splicing of the doublesex master switch gene. In ZZ males of this female heterogametic system, the female

Sex- and dose-dependency in the pharmacokinetics and pharmacodynamics of (+)-methamphetamine and its metabolite (+)-amphetamine in rats

International Nuclear Information System (INIS)

Milesi-Halle, Alessandra; Hendrickson, Howard P.; Laurenzana, Elizabeth M.; Gentry, W. Brooks; Owens, S. Michael

2005-01-01

These studies investigated how (+)-methamphetamine (METH) dose and rat sex affect the pharmacological response to METH in Sprague-Dawley rats. The first set of experiments determined the pharmacokinetics of METH and its pharmacologically active metabolite (+)-amphetamine (AMP) in male and female Sprague-Dawley rats after 1.0 and 3.0 mg/kg METH doses. The results showed significant sex-dependent changes in METH pharmacokinetics, and females formed significantly lower amounts of AMP. While the area under the serum concentration-time curve in males increased proportionately with the METH dose, the females showed a disproportional increase. The sex differences in systemic clearance, renal clearance, volume of distribution, and percentage of unchanged METH eliminated in the urine suggested dose-dependent pharmacokinetics in female rats. The second set of studies sought to determine the behavioral implications of these pharmacokinetic differences by quantifying locomotor activity in male and female rats after saline, 1.0, and 3.0 mg/kg METH. The results showed sex- and dose-dependent differences in METH-induced locomotion, including profound differences in the temporal profile of effects at higher dose. These findings show that the pharmacokinetic and metabolic profile of METH (slower METH clearance and lower AMP metabolite formation) plays a significant role in the differential pharmacological response to METH in male and female rats

Genes involved in sex determination and the influence of ...

African Journals Online (AJOL)

As the sex reversal is a highly desired process in fish farming aiming at obtaining male mono-sexual populations (due to weight gain of males), several techniques based on direct and indirect manipulation of phenotypic sex are being tested. Recent surveys show the use of temperature as alternative to the process of sex ...

Sex determination mechanisms in the Calliphoridae (blow flies).

Science.gov (United States)

Scott, M J; Pimsler, M L; Tarone, A M

2014-01-01

The Calliphoridae or blow flies are a family of insects that occupy diverse habitats and perform important ecological roles, particularly the decomposition of animal remains. Some Calliphoridae species are also important in the forensic sciences, in agriculture (e.g. as livestock pests) and in medicine (e.g. maggot therapy). Calliphoridae provide striking examples in support of the hypothesis that sex determination regulatory gene hierarchies evolve in the reverse order, with the gene at the top being the most recently added. Unlike the model fly Drosophila melanogaster, where sex is determined by the number of X chromosomes, in the Australian sheep blow fly (Lucilia cuprina) sex is determined by a Y-linked male-determining gene (M). A different regulatory system appears to operate in the hairy maggot blow fly (Chrysomya rufifacies) where the maternal genotype determines sex. It is hypothesized that females heterozygous for a dominant female-determining factor (F/f) produce only female offspring and homozygous f/f females produce only sons. The bottom of the regulatory hierarchy appears to be the same in D. melanogaster and L. cuprina, with sex-specific splicing of doublesex transcripts being controlled by the female-specific Transformer (TRA) protein. We discuss a model that has been proposed for how tra transcripts are sex-specifically spliced in calliphorids, which is very different from D. melanogaster. © 2013 S. Karger AG, Basel.

Cretaceous park of sex determination: sex chromosomes are conserved across iguanas.

Science.gov (United States)

Rovatsos, Michail; Pokorná, Martina; Altmanová, Marie; Kratochvíl, Lukáš

2014-03-01

Many poikilothermic vertebrate lineages, especially among amphibians and fishes, possess a rapid turnover of sex chromosomes, while in endotherms there is a notable stability of sex chromosomes. Reptiles in general exhibit variability in sex-determining systems; as typical poikilotherms, they might be expected to have a rapid turnover of sex chromosomes. However, molecular data which would enable the testing of the stability of sex chromosomes are lacking in most lineages. Here, we provide molecular evidence that sex chromosomes are highly conserved across iguanas, one of the most species-rich clade of reptiles. We demonstrate that members of the New World families Iguanidae, Tropiduridae, Leiocephalidae, Phrynosomatidae, Dactyloidae and Crotaphytidae, as well as of the family Opluridae which is restricted to Madagascar, all share homologous sex chromosomes. As our sampling represents the majority of the phylogenetic diversity of iguanas, the origin of iguana sex chromosomes can be traced back in history to the basal splitting of this group which occurred during the Cretaceous period. Iguanas thus show a stability of sex chromosomes comparable to mammals and birds and represent the group with the oldest sex chromosomes currently known among amniotic poikilothermic vertebrates.

Similar temperature dependencies of glycolytic enzymes: an evolutionary adaptation to temperature dynamics?

Directory of Open Access Journals (Sweden)

Cruz Luisa Ana B

2012-12-01

Full Text Available Abstract Background Temperature strongly affects microbial growth, and many microorganisms have to deal with temperature fluctuations in their natural environment. To understand regulation strategies that underlie microbial temperature responses and adaptation, we studied glycolytic pathway kinetics in Saccharomyces cerevisiae during temperature changes. Results Saccharomyces cerevisiae was grown under different temperature regimes and glucose availability conditions. These included glucose-excess batch cultures at different temperatures and glucose-limited chemostat cultures, subjected to fast linear temperature shifts and circadian sinoidal temperature cycles. An observed temperature-independent relation between intracellular levels of glycolytic metabolites and residual glucose concentration for all experimental conditions revealed that it is the substrate availability rather than temperature that determines intracellular metabolite profiles. This observation corresponded with predictions generated in silico with a kinetic model of yeast glycolysis, when the catalytic capacities of all glycolytic enzymes were set to share the same normalized temperature dependency. Conclusions From an evolutionary perspective, such similar temperature dependencies allow cells to adapt more rapidly to temperature changes, because they result in minimal perturbations of intracellular metabolite levels, thus circumventing the need for extensive modification of enzyme levels.

On the temperature dependence of the excess resistivity in dilute volatile alloys

International Nuclear Information System (INIS)

Uray, L.; Vicsek, T.

1978-01-01

In recrystallized wires of many important refractory alloys, an appreciable part of the temperature dependence of the measured excess resistivity is related to the radial distribution of the volatile solutes (extrinsic temperature dependence). Both the extrinsic and the intrinsic part of the temperature dependence of the excess resistivity have been determined for dilute WFe, WCo and WRe alloys, by measuring the resistance as a function of temperature and the thickness of layers removed by electrothinning. In this way the parameters of the evaporation profiles were also determined. In the surface region at low temperatures the length scale of the inhomogeneity is comparable to the mean-free path. Therefore, the observed extrinsic temperature dependence of the excess resistivity was calculated directly from the Boltzmann equation. The WCo alloy is a Kondo system, since its resistivity shows a minimum a 20 K. (author)

Transgenerational plasticity mitigates the impact of global warming to offspring sex ratios.

Science.gov (United States)

Donelson, Jennifer M; Munday, Philip L

2015-08-01

Global warming poses a threat to organisms with temperature-dependent sex determination because it can affect operational sex ratios. Using a multigenerational experiment with a marine fish, we provide the first evidence that parents developing from early life at elevated temperatures can adjust their offspring gender through nongenetic and nonbehavioural means. However, this adjustment was not possible when parents reproduced, but did not develop, at elevated temperatures. Complete restoration of the offspring sex ratio occurred when parents developed at 1.5 °C above the present-day average temperature for one generation. However, only partial improvement in the sex ratio occurred at 3.0 °C above average conditions, even after two generations, suggesting a limitation to transgenerational plasticity when developmental temperature is substantially increased. This study highlights the potential for transgenerational plasticity to ameliorate some impacts of climate change and that development from early life may be essential for expression of transgenerational plasticity in some traits. © 2015 John Wiley & Sons Ltd.

A new component of the Nasonia sex determining cascade is maternally silenced and regulates transformer expression.

Science.gov (United States)

Verhulst, Eveline C; Lynch, Jeremy A; Bopp, Daniel; Beukeboom, Leo W; van de Zande, Louis

2013-01-01

Although sex determination is a universal process in sexually reproducing organisms, sex determination pathways are among the most highly variable genetic systems found in nature. Nevertheless, general principles can be identified among the diversity, like the central role of transformer (tra) in insects. When a functional TRA protein is produced in early embryogenesis, the female sex determining route is activated, while prevention of TRA production leads to male development. In dipterans, male development is achieved by prevention of female-specific splicing of tra mRNA, either mediated by X-chromosome dose or masculinizing factors. In Hymenoptera, which have haplodiploid sex determination, complementary sex determination and maternal imprinting have been identified to regulate timely TRA production. In the parasitoid Nasonia, zygotic transformer (Nvtra) expression and splicing is regulated by a combination of maternal provision of Nvtra mRNA and silencing of Nvtra expression in unfertilized eggs. It is unclear, however, if this silencing is directly on the tra locus or whether it is mediated through maternal silencing of a trans-acting factor. Here we show that in Nasonia, female sex determination is dependent on zygotic activation of Nvtra expression by an as yet unknown factor. This factor, which we propose to term womanizer (wom), is maternally silenced during oogenesis to ensure male development in unfertilized eggs. This finding implicates the upstream recruitment of a novel gene in the Nasonia sex determining cascade and supports the notion that sex determining cascades can rapidly change by adding new components on top of existing regulators.

A New Component of the Nasonia Sex Determining Cascade Is Maternally Silenced and Regulates Transformer Expression

Science.gov (United States)

Bopp, Daniel; Beukeboom, Leo W.; van de Zande, Louis

2013-01-01

Although sex determination is a universal process in sexually reproducing organisms, sex determination pathways are among the most highly variable genetic systems found in nature. Nevertheless, general principles can be identified among the diversity, like the central role of transformer (tra) in insects. When a functional TRA protein is produced in early embryogenesis, the female sex determining route is activated, while prevention of TRA production leads to male development. In dipterans, male development is achieved by prevention of female-specific splicing of tra mRNA, either mediated by X-chromosome dose or masculinizing factors. In Hymenoptera, which have haplodiploid sex determination, complementary sex determination and maternal imprinting have been identified to regulate timely TRA production. In the parasitoid Nasonia, zygotic transformer (Nvtra) expression and splicing is regulated by a combination of maternal provision of Nvtra mRNA and silencing of Nvtra expression in unfertilized eggs. It is unclear, however, if this silencing is directly on the tra locus or whether it is mediated through maternal silencing of a trans-acting factor. Here we show that in Nasonia, female sex determination is dependent on zygotic activation of Nvtra expression by an as yet unknown factor. This factor, which we propose to term womanizer (wom), is maternally silenced during oogenesis to ensure male development in unfertilized eggs. This finding implicates the upstream recruitment of a novel gene in the Nasonia sex determining cascade and supports the notion that sex determining cascades can rapidly change by adding new components on top of existing regulators. PMID:23717455

Study of Cu-Al-Zn alloys hardness temperature dependence

International Nuclear Information System (INIS)

Kurmanova, D.T.; Skakov, M.K.; Melikhov, V.D.

2001-01-01

In the paper the results of studies for the Cu-Al-Zn ternary alloys hardness temperature dependence are presented. The method of 'hot hardness' has been used during study of the solid state phase transformations and under determination of the hot stability boundaries. Due to the samples brittleness a hardness temperature dependence definition is possible only from 350-400 deg. C. Sensitivity of the 'hot hardness' method is decreasing within high plasticity range, so the measurements have been carried out only up to 700-800 deg. C. It is shown, that the alloys hardness dependence character from temperature is close to exponential one within the certain structure modification existence domain

Parp1 protects against Aag-dependent alkylation-induced nephrotoxicity in a sex-dependent manner.

Science.gov (United States)

Calvo, Jennifer A; Allocca, Mariacarmela; Fake, Kimberly R; Muthupalani, Sureshkumar; Corrigan, Joshua J; Bronson, Roderick T; Samson, Leona D

2016-07-19

Nephrotoxicity is a common toxic side-effect of chemotherapeutic alkylating agents. Although the base excision repair (BER) pathway is essential in repairing DNA alkylation damage, under certain conditions the initiation of BER produces toxic repair intermediates that damage healthy tissues. We have shown that the alkyladenine DNA glycosylase, Aag (a.k.a. Mpg), an enzyme that initiates BER, mediates alkylation-induced whole-animal lethality and cytotoxicity in the pancreas, spleen, retina, and cerebellum, but not in the kidney. Cytotoxicity in both wild-type and Aag-transgenic mice (AagTg) was abrogated in the absence of Poly(ADP-ribose) polymerase-1 (Parp1). Here we report that Parp1-deficient mice expressing increased Aag (AagTg/Parp1-/-) develop sex-dependent kidney failure upon exposure to the alkylating agent, methyl methanesulfonate (MMS), and suffer increased whole-animal lethality compared to AagTg and wild-type mice. Macroscopic, histological, electron microscopic and immunohistochemical analyses revealed morphological kidney damage including dilated tubules, proteinaceous casts, vacuolation, collapse of the glomerular tuft, and deterioration of podocyte structure. Moreover, mice exhibited clinical signs of kidney disease indicating functional damage, including elevated blood nitrogen urea and creatinine, hypoproteinemia and proteinuria. Pharmacological Parp inhibition in AagTg mice also resulted in sensitivity to MMS-induced nephrotoxicity. These findings provide in vivo evidence that Parp1 modulates Aag-dependent MMS-induced nephrotoxicity in a sex-dependent manner and highlight the critical roles that Aag-initiated BER and Parp1 may play in determining the side-effects of chemotherapeutic alkylating agents.

Determination of the Temperature Dependence of Heat Capacity for Some Molecular Crystals of Nitro Compounds

Science.gov (United States)

Kovalev, Yu. M.; Kuropatenko, V. F.

2018-05-01

An analysis of the existing approximations used for describing the dependence of heat capacity at a constant volume on the temperature of a molecular crystal has been carried out. It is shown that the considered Debye and Einstein approximations do not enable one to adequately describe the dependence of heat capacity at a constant volume on the temperature of the molecular crystals of nitro compounds. This inference requires the development of special approximations that would describe both low-frequency and high-frequency parts of the vibrational spectra of molecular crystals. This work presents a universal dependence allowing one to describe the dependence of heat capacity at a constant volume on temperature for a number of molecular crystals of nitro compounds.

Insect sex determination : It all evolves around transformer

NARCIS (Netherlands)

Verhulst, Eveline C.; van de Zande, Louis; Beukeboom, Leo W.

Insects exhibit a variety of sex determining mechanisms including male or female heterogamety and haplodiploidy. The primary signal that starts sex determination is processed by a cascade of genes ending with the conserved switch doublesex that controls sexual differentiation. Transformer is the

Genetics of sex determination in the haplodiploid wasp Nasonia ...

Indian Academy of Sciences (India)

2010-09-06

Sep 6, 2010 ... How gender is determined under haplodiploidy in the ab- sence of heteromorphic sex ... determination (see below). Sex-determination mutants ... not others (Nöthiger and Steinmann-Zwicky 1985; Wilkins. 1995; Saccone et al.

Age- and sex-dependent model for estimating radioiodine dose to a normal thyroid

International Nuclear Information System (INIS)

Killough, G.G.; Eckerman, K.F.

1985-01-01

This paper describes the derivation of an age- and sex-dependent model of radioiodine dosimetry in the thyroid and the application of the model to estimating the thyroid dose for each of 4215 patients who were exposed to 131 I in diagnostic and therapeutic procedures. The model was made to conform to these data requirements by the use of age-specific estimates of the biological half-time of iodine in the thyroid and an age- and sex-dependent representation of the mass of the thyroid. Also, it was assumed that the thyroid burden was maximum 24 hours after administration (the 131 I dose is not critically sensitive to this assumption). The metabolic model is of the form A(t) = K[exp(-μ 1 t) - exp(-μ 2 t)] (μCi), where μ 1 = lambda/sub r/ + lambda/sub i//sup b/ (i = 1, 2), lambda/sub r/ is the radiological decay-rate coefficient, and lambda/sub i//sup b/ are biological removal rate coefficients. The values of lambda/sub i//sup b/ are determined by solving a nonlinear equation that depends on assumptions about the time of maximum uptake and the eventual biological loss rate (through which age dependence enters). The value of K may then be calculated from knowledge of the uptake at a particular time. The dosimetric S-factor (rad/μCi-day) is based on specific absorbed fractions for photons of energy ranging from 0.01 to 4.0 MeV for thyroid masses from 1.29 to 19.6 g; the functional form of the S-factor also involves the thyroid mass explicitly, through which the dependence on age and sex enters. An analysis of sensitivity of the model to uncertainties in the thyroid mass and the biological removal rate for several age groups is reported. The model could prove useful in the dosimetry of very short-lived radioiodines. Tables of age- and sex-dependent coefficients are provided to enable readers to make their own calculations. 12 refs., 5 figs., 4 tabs

Genetic architecture of sex determination in fish: Applications to sex ratio control in aquaculture

Directory of Open Access Journals (Sweden)

Paulino eMartínez

2014-09-01

Full Text Available Controlling the sex ratio is essential in finfish farming. A balanced sex ratio is usually good for broodstock management, since it enables to develop appropriate breeding schemes. However, in some species the production of monosex populations is desirable because the existence of sexual dimorphism, primarily in growth or first time of sexual maturation, but also in color or shape, can render one sex more valuable. The knowledge of the genetic architecture of sex determination (SD is convenient for controlling sex ratio and for the implementation of breeding programs. Unlike mammals and birds, which show highly conserved master genes that control a conserved genetic network responsible for gonad differentiation (GD, a huge diversity of SD mechanisms has been reported in fish. Despite theory predictions, more than one gene is in many cases involved in fish SD and genetic differences have been observed in the GD network. Environmental factors also play a relevant role and epigenetic mechanisms are becoming increasingly recognized for the establishment and maintenance of the GD pathways. Although major genetic factors are frequently involved in fish SD, these observations strongly suggest that SD in this group resembles a complex trait. Accordingly, the application of quantitative genetics combined with genomic tools is desirable to address its study and in fact, when applied, it has frequently demonstrated a multigene trait interacting with environmental factors in model and cultured fish species. This scenario has notable implications for aquaculture and, depending upon the species, from chromosome manipulation or environmental control techniques up to classical selection or marker assisted selection programs, are being applied. In this review, we selected four relevant species or fish groups to illustrate this diversity and hence the technologies that can be used by the industry for the control of sex ratio: turbot and European sea bass, two

Sex Reversal in Reptiles: Reproductive Oddity or Powerful Driver of Evolutionary Change?

Science.gov (United States)

Holleley, Clare E; Sarre, Stephen D; O'Meally, Denis; Georges, Arthur

2016-01-01

Is sex a product of genes, the environment, or both? In this review, we describe the diversity of sex-determining mechanisms in reptiles, with a focus on systems that display gene-environment interactions. We summarise the field and laboratory-based evidence for the occurrence of environmental sex reversal in reptiles and ask whether this is a widespread evolutionary mechanism affecting the evolution of sex chromosomes and speciation in vertebrates. Sex determination systems exist across a continuum of genetic and environmental influences, blurring the lines between what was once considered a strict dichotomy between genetic sex determination and temperature-dependent sex determination. Across this spectrum, we identify the potential for sex reversal in species with clearly differentiated heteromorphic sex chromosomes (Pogona vitticeps, Bassiana duperreyi, Eremias multiocellata, Gekko japonicus), weakly differentiated homomorphic sex chromosomes (Niveoscincus ocellatus), and species with only a weak heritable predisposition for sex (Emys orbicularis, Trachemys scripta). We argue that sex reversal is widespread in reptiles (Testudines, Lacertidae, Agamidae, Scincidae, Gekkonidae) and has the potential to have an impact on individual fitness, resulting in reproductively, morphologically, and behaviourally unique phenotypes. Sex reversal is likely to be a powerful evolutionary force responsible for generating and maintaining lability and diversity in reptile sex-determining modes. © 2016 S. Karger AG, Basel.

SEX DETERMINATION FROM FEMORAL HEAD DIAMETERS IN ...

African Journals Online (AJOL)

hi-tech

2000-03-01

Mar 1, 2000 ... In medico-legal cases where sophisticated methods of sex determination is lacking, these ... scientific methods(3). Using the visual method ... between the sexes and the values of the right and left femoral head diameters.

Environmental sex determination in the branchiopod crustacean Daphnia magna: deep conservation of a Doublesex gene in the sex-determining pathway.

Directory of Open Access Journals (Sweden)

Yasuhiko Kato

2011-03-01

Full Text Available Sex-determining mechanisms are diverse among animal lineages and can be broadly divided into two major categories: genetic and environmental. In contrast to genetic sex determination (GSD, little is known about the molecular mechanisms underlying environmental sex determination (ESD. The Doublesex (Dsx genes play an important role in controlling sexual dimorphism in genetic sex-determining organisms such as nematodes, insects, and vertebrates. Here we report the identification of two Dsx genes from Daphnia magna, a freshwater branchiopod crustacean that parthenogenetically produces males in response to environmental cues. One of these genes, designated DapmaDsx1, is responsible for the male trait development when expressed during environmental sex determination. The domain organization of DapmaDsx1 was similar to that of Dsx from insects, which are thought to be the sister group of branchiopod crustaceans. Intriguingly, the molecular basis for sexually dimorphic expression of DapmaDsx1 is different from that of insects. Rather than being regulated sex-specifically at the level of pre-mRNA splicing in the coding region, DapmaDsx1 exhibits sexually dimorphic differences in the abundance of its transcripts. During embryogenesis, expression of DapmaDsx1 was increased only in males and its transcripts were primarily detected in male-specific structures. Knock-down of DapmaDsx1 in male embryos resulted in the production of female traits including ovarian maturation, whereas ectopic expression of DapmaDsx1 in female embryos resulted in the development of male-like phenotypes. Expression patterns of another D. magna Dsx gene, DapmaDsx2, were similar to those of DapmaDsx1, but silencing and overexpression of this gene did not induce any clear phenotypic changes. These results establish DapmaDsx1 as a key regulator of the male phenotype. Our findings reveal how ESD is implemented by selective expression of a fundamental genetic component that is

Sex modulates approach systems and impulsivity in substance dependence.

Science.gov (United States)

Perry, Robert I; Krmpotich, Theodore; Thompson, Laetitia L; Mikulich-Gilbertson, Susan K; Banich, Marie T; Tanabe, Jody

2013-11-01

Personality traits such as pathological engagement in approach behaviors, high levels of impulsivity and heightened negative affect are consistently observed in substance dependent individuals (SDI). The clinical course of addiction has been shown to differ between sexes. For example, women increase their rates of consumption of some drugs of abuse more quickly than men. Despite the potential influence of personality and sex on features of addiction, few studies have investigated the interaction of these factors in substance dependence. Fifty-one SDI (26 males, 25 females) and 66 controls (41 males, 25 females) completed the Behavioral Inhibition/Behavioral Activation System (BIS/BAS) Scales, the Barratt Impulsiveness Scale, and the Positive and Negative Affect Schedule (PANAS-X). Data were analyzed with 2×2 ANCOVAs testing for main effects of group, sex and group by sex interactions, adjusting for education level. Significant group by sex interactions were observed for BAS scores [F(1,116)=7.03, pImpulsiveness [F(1,116)=6.11, pimpulsivity followed by male SDI, male controls, and finally female controls. SDI scored higher on negative affect [F(1,116)=25.23, pwomen than men [F(1,116)=14.03, pimpulsivity in SDI women relative to SDI men and control women suggest that personality traits that have been previously associated with drug use may be modulated by sex. These factors may contribute to differences in the disease course observed in male compared to female drug users. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Temperature dependence of the dispersion of single crystals SrCl/sub 2/. [Temperature coefficient

Energy Technology Data Exchange (ETDEWEB)

Kuzin, M P [L' vovskij Gosudarstvennyj Univ. (Ukrainian SSR)

1976-01-01

The dispersion of the refractive index of SrCl/sub 2/ monocrystals in the spectral range 300-700 nm at temperatures of 223, 295 adn 373 K has been studied. The temperature coefficient of the refractive index as a function of the wave length has been determined for the room temperature. The function resembles the corresponding dependence for alkali-halide crystals.

Sex Determination in Insects: a binary decision based on alternative splicing

OpenAIRE

Salz, Helen K.

2011-01-01

The gene regulatory networks that control sex determination vary between species. Despite these differences, comparative studies in insects have found that alternative splicing is reiteratively used in evolution to control expression of the key sex determining genes. Sex determination is best understood in Drosophila where activation of the RNA binding protein encoding gene Sex-lethal is the central female-determining event. Sex-lethal serves as a genetic switch because once activated it cont...

An inelastic neutron scattering determination of the temperature dependence of the 3d-4f exchange interaction in Sm2Fe17

International Nuclear Information System (INIS)

Solodovnikov, Anton; Loewenhaupt, Michael; Moze, Oscar; Kuz'min, Michael D.; Bewley, Robert

2002-01-01

High energy transfer inelastic neutron scattering has been used to investigate the temperature dependence in the range from 20 to 450 K of the intermultiplet transition E inter in the intermetallic compound Sm 2 Fe 17 . The peak due to this transition, observed in the inelastic neutron spectrum, shifts to lower energies with increasing temperature. From the temperature dependence of E inter , the temperature dependence of the exchange field B ex acting on the Sm ion has been established experimentally, as the energy of the intermultiplet transition provides a direct value for the exchange field. At the highest measured temperature T=450 K, which is above the Curie point of 389 K for this compound, the transition energy is situated just above the bare spin-orbit splitting for Sm 3+ . The method utilized in the present investigation offers a rather easy and direct way to determine B ex in a large range of Sm intermetallics, which form an interesting class of hard magnetic materials

Associations of prodynorphin sequence variation with alcohol dependence and related traits are phenotype-specific and sex-dependent.

Science.gov (United States)

Winham, Stacey J; Preuss, Ulrich W; Geske, Jennifer R; Zill, Peter; Heit, John A; Bakalkin, Georgy; Biernacka, Joanna M; Karpyak, Victor M

2015-10-27

We previously demonstrated that prodynorphin (PDYN) haplotypes and single nucleotide polymorphism (SNP) rs2281285 are associated with alcohol dependence and the propensity to drink in negative emotional states, and recent studies suggest that PDYN gene effects on substance dependence risk may be sex-related. We examined sex-dependent associations of PDYN variation with alcohol dependence and related phenotypes, including negative craving, time until relapse after treatment and the length of sobriety episodes before seeking treatment, in discovery and validation cohorts of European ancestry. We found a significant haplotype-by-sex interaction (p  =  0.03), suggesting association with alcohol dependence in males (p = 1E-4) but not females. The rs2281285 G allele increased risk for alcohol dependence in males in the discovery cohort (OR = 1.49, p = 0.002), with a similar trend in the validation cohort (OR = 1.35, p = 0.086). However, rs2281285 showed a trend towards association with increased negative craving in females in both the discovery (beta = 10.16, p = 0.045) and validation samples (OR = 7.11, p = 0.066). In the discovery cohort, rs2281285 was associated with time until relapse after treatment in females (HR = 1.72, p = 0.037); in the validation cohort, it was associated with increased length of sobriety episodes before treatment in males (beta = 13.49, p = 0.001). Our findings suggest that sex-dependent effects of PDYN variants in alcohol dependence are phenotype-specific.

Breeding sex ratio and population size of loggerhead turtles from Southwestern Florida.

Directory of Open Access Journals (Sweden)

Jacob A Lasala

Full Text Available Species that display temperature-dependent sex determination are at risk as a result of increasing global temperatures. For marine turtles, high incubation temperatures can skew sex ratios towards females. There are concerns that temperature increases may result in highly female-biased offspring sex ratios, which would drive a future sex ratio skew. Studying the sex ratios of adults in the ocean is logistically very difficult because individuals are widely distributed and males are inaccessible because they remain in the ocean. Breeding sex ratios (BSR are sought as a functional alternative to study adult sex ratios. One way to examine BSR is to determine the number of males that contribute to nests. Our goal was to evaluate the BSR for loggerhead turtles (Caretta caretta nesting along the eastern Gulf of Mexico in Florida, from 2013-2015, encompassing three nesting seasons. We genotyped 64 nesting females (approximately 28% of all turtles nesting at that time and up to 20 hatchlings from their nests (n = 989 using 7 polymorphic microsatellite markers. We identified multiple paternal contributions in 70% of the nests analyzed and 126 individual males. The breeding sex ratio was approximately 1 female for every 2.5 males. We did not find repeat males in any of our nests. The sex ratio and lack of repeating males was surprising because of female-biased primary sex ratios. We hypothesize that females mate offshore of their nesting beaches as well as en route. We recommend further comparisons of subsequent nesting events and of other beaches as it is imperative to establish baseline breeding sex ratios to understand how growing populations behave before extreme environmental effects are evident.

Sex ratio selection and multi-factorial sex determination in the housefly : A dynamic model

NARCIS (Netherlands)

Kozielska, M.A.; Pen, I.R.; Beukeboom, L.W.; Weissing, F.J.

Sex determining (SD) mechanisms are highly variable between different taxonomic groups and appear to change relatively quickly during evolution. Sex ratio selection could be a dominant force causing such changes. We investigate theoretically the effect of sex ratio selection on the dynamics of a

Development and application of genetic sexing systems for the Mediterranean fruit fly based on a temperature sensitive lethal mutation

International Nuclear Information System (INIS)

Franz, G.; Willhoeft, U.; Kerremans, P.; Hendrichs, J.; Rendon, P.

1997-01-01

The present status in genetic sexing for the Mediterranean fruit fly is discussed. This includes the selection of the appropriate sexing gene (which determines the feasibility and practical applicability of the sexing system) as well as the selection of the appropriate Y-autosome translocation (which determines the stability of the sexing system). A temperature sensitive lethal mutation is used to eliminate females during the egg stage. This mutation in combination with new Y-autosome translocations allowed the construction of a genetic sexing strain, named VIENNA-42, that is stable enough for large scale mass rearing. Also described are the analysis of this strain under field cage and field conditions and, in preparation for large scale tests in Guatemala, the outcrossing of VIENNA-42 with genetic material from the target area. (author)

Size-dependent sex allocation in Aconitum gymnandrum (Ranunculaceae): physiological basis and effects of maternal family and environment.

Science.gov (United States)

Zhao, Z-G; Meng, J-L; Fan, B-L; Du, G-Z

2008-11-01

Theory predicts size-dependent sex allocation (SDS): flowers on plants with a high-resource status should have larger investment in females than plants with a low-resource status. Through a pot experiment with Aconitum gymnandrum (Ranunculaceae) in the field, we examined the relationship between sex allocation of individual flowers and plant size for different maternal families under different environmental conditions. We also determined the physiological base of variations in plant size. Our results support the prediction of SDS, and show that female-biased allocation with plant size is consistent under different environmental conditions. Negative correlations within families showed a plastic response of sex allocation to plant size. Negative genetic correlations between sex allocation and plant size at the family level indicate a genetic cause of the SDS pattern, although genetic correlation was influenced by environmental factors. Hence, the size-dependency of sex allocation in this species had both plastic and genetic causes. Furthermore, genotypes that grew large also had higher assimilation ability, thus showing a physiological basis for SDS.

Incubation temperature affects the behavior of adult leopard geckos (Eublepharis macularius).

Science.gov (United States)

Flores, D; Tousignant, A; Crews, D

1994-06-01

The leopard gecko has temperature-dependent sex determination (TSD); females are predominantly produced when incubated at 26 degrees C (100%), 30 degrees C (70%), and 34 degrees C (95%), whereas males are predominantly produced at 32.5 degrees C (75%). Exogenous estradiol can override the effect of temperature on sex determination. To compare temperature-determined females with hormone-determined females, eggs from the male-biased temperature were treated with estradiol benzoate during incubation. As adults, animals from a male-biased incubation temperature were more likely to exhibit aggression than animals from female-biased incubation temperatures. Furthermore, females from a male-biased incubation temperature tended to be less attractive than females from female-biased temperatures. Hormone-determined females were both attractive and aggressive. This suggests that incubation temperature is an important development determinant of adult aggressiveness and attractiveness. The 26 degrees C animals ovariectomized on the day of hatch exhibited more frequent aggression and were unreceptive to males, indicating that postnatal ovarian hormones also play a role in adult sociosexual behaviors. The parallel between incubation temperature and intrauterine position in laboratory mammals is discussed.

Characterization and expression profile of the ovarian cytochrome P-450 aromatase (cyp19A1) gene during thermolabile sex determination in Pejerrey, Odontesthes bonariensis

Science.gov (United States)

Karube, M.; Fernandino, J.I.; Strobl-Mazzulla, P.; Strussmann, C.A.; Yoshizaki, G.; Somoza, G.M.; Patino, R.

2007-01-01

Cytochrome P450 aromatase (cyp19) is an enzyme that catalyzes the conversion of androgens to estrogens and may play a role in temperature- dependent sex determination (TSD) of reptiles, amphibians, and fishes. In this study, the ovarian P450 aromatase form (cyp19A1) of pejerrey Odontesthes bonariensis, a teleost with marked TSD, was cloned and its expression profile evaluated during gonadal differentiation at feminizing (17??C, 100% females), mixed-sex producing (24 and 25??C, 73.3 and 26.7% females, respectively), and masculinizing (29??C, 0% females) temperatures. The deduced cyp19A1 amino acid sequence shared high identity (>77.8%) with that from other teleosts but had low identity (<61.8%) with brain forms (cyp19A2), including that of pejerrey itself. The tissue distribution analysis of cyp19A1 mRNA in adult fish revealed high expression in the ovary. Semi-quantitative reverse transcription polymerase chain reaction analysis of the bodies of larvae revealed that cyp19A1 expression increased before the appearance of the first histological signs of ovarian differentiation at the feminizing temperature but remained low at the masculinizing temperature. The expression levels at mixed-sex producing temperatures were bimodal rather than intermediate, showing low and high modal values similar to those at the feminizing and masculinizing temperatures, respectively. The population percentages of high and low expression levels at intermediate temperatures were proportional to the percentage of females and males, respectively, and high levels were first observed at about the time of sex differentiation of females. These results suggest that cyp19A1 is involved in the process of ovarian formation and possibly also in the TSD of pejerrey. ?? 2007 Wiley-Liss, Inc.

Rapid quantification and sex determination of forensic evidence materials.

Science.gov (United States)

Andréasson, Hanna; Allen, Marie

2003-11-01

DNA quantification of forensic evidence is very valuable for an optimal use of the available biological material. Moreover, sex determination is of great importance as additional information in criminal investigations as well as in identification of missing persons, no suspect cases, and ancient DNA studies. While routine forensic DNA analysis based on short tandem repeat markers includes a marker for sex determination, analysis of samples containing scarce amounts of DNA is often based on mitochondrial DNA, and sex determination is not performed. In order to allow quantification and simultaneous sex determination on minute amounts of DNA, an assay based on real-time PCR analysis of a marker within the human amelogenin gene has been developed. The sex determination is based on melting curve analysis, while an externally standardized kinetic analysis allows quantification of the nuclear DNA copy number in the sample. This real-time DNA quantification assay has proven to be highly sensitive, enabling quantification of single DNA copies. Although certain limitations were apparent, the system is a rapid, cost-effective, and flexible assay for analysis of forensic casework samples.

Sex determination in insects: a binary decision based on alternative splicing.

Science.gov (United States)

Salz, Helen K

2011-08-01

The gene regulatory networks that control sex determination vary between species. Despite these differences, comparative studies in insects have found that alternative splicing is reiteratively used in evolution to control expression of the key sex-determining genes. Sex determination is best understood in Drosophila where activation of the RNA binding protein-encoding gene Sex-lethal is the central female-determining event. Sex-lethal serves as a genetic switch because once activated it controls its own expression by a positive feedback splicing mechanism. Sex fate choice in is also maintained by self-sustaining positive feedback splicing mechanisms in other dipteran and hymenopteran insects, although different RNA binding protein-encoding genes function as the binary switch. Studies exploring the mechanisms of sex-specific splicing have revealed the extent to which sex determination is integrated with other developmental regulatory networks. Copyright © 2011 Elsevier Ltd. All rights reserved.

Sex Differences in Objective and Projective Dependency Tests: A Meta-Analytic Review.

Science.gov (United States)

Bornstein, Robert F.

1995-01-01

A meta-analysis of 97 studies published since 1950 that assessed sex differences in scores on objective and projective dependency tests indicated that women consistently obtained higher dependency scores on objective tests, and men obtained higher scores on projective tests. Findings are discussed in terms of sex role socialization. (SLD)

Temperature and emissivity determination of liquid steel S235

Science.gov (United States)

Schöpp, H.; Sperl, A.; Kozakov, R.; Gött, G.; Uhrlandt, D.; Wilhelm, G.

2012-06-01

Temperature determination of liquid metals is difficult but a necessary tool for improving materials and processes such as arc welding in the metal-working industry. A method to determine the surface temperature of the weld pool is described. A TIG welding process and absolute calibrated optical emission spectroscopy are used. This method is combined with high-speed photography. 2D temperature profiles are obtained. The emissivity of the radiating surface has an important influence on the temperature determination. A temperature dependent emissivity for liquid steel is given for the spectral region between 650 and 850 nm.

Temperature and emissivity determination of liquid steel S235

International Nuclear Information System (INIS)

Schöpp, H; Kozakov, R; Gött, G; Uhrlandt, D; Sperl, A; Wilhelm, G

2012-01-01

Temperature determination of liquid metals is difficult but a necessary tool for improving materials and processes such as arc welding in the metal-working industry. A method to determine the surface temperature of the weld pool is described. A TIG welding process and absolute calibrated optical emission spectroscopy are used. This method is combined with high-speed photography. 2D temperature profiles are obtained. The emissivity of the radiating surface has an important influence on the temperature determination. A temperature dependent emissivity for liquid steel is given for the spectral region between 650 and 850 nm. (paper)

Occupational Segregation by Sex: Determinants and Changes.

Science.gov (United States)

Beller, Andrea H.

1982-01-01

This study found that occupational sex segregation began to diminish during the 1970s, in conjunction with enforcement of the equal employment opportunity laws against sex discrimination in employment. The success of these laws suggests that discrimination was originally a determinant of occupational segregation. (Author/SK)

Evidence of oligogenic sex determination in the apple snail Pomacea canaliculata.

Science.gov (United States)

Yusa, Yoichi; Kumagai, Natsumi

2018-02-26

A small number of genes may interact to determine sex, but few such examples have been demonstrated in animals, especially through comprehensive mating experiments. The highly invasive apple snail Pomacea canaliculata is gonochoristic and shows a large variation in brood sex ratio, and the involvement of multiple genes has been suggested for this phenomenon. We conducted mating experiments to determine whether their sex determination involves a few or many genes (i.e., oligogenic or polygenic sex determination, respectively). Full-sib females or males that were born from the same parents were mated to an adult of the opposite sex, and the brood sex ratios of the parents and their offspring were investigated. Analysis of a total of 4288 offspring showed that the sex ratios of offspring from the full-sib females were variable but clustered into only a few values. Similar patterns were observed for the full-sib males, although the effect was less clear because fewer offspring were used (n = 747). Notably, the offspring sex ratios of all full-sib females in some families were nearly 0.5 (proportion of males) with little variation. These results indicate that the number of genotypes of the full-sibs, and hence genes involved in sex determination, is small in this snail. Such oligogenic systems may be a major sex-determining system among animals, especially those with variable sex ratios.

Evolutionary diversity and turn-over of sex determination in teleost fishes.

Science.gov (United States)

Mank, J E; Avise, J C

2009-01-01

Sex determination, due to the obvious association with reproduction and Darwinian fitness, has been traditionally assumed to be a relatively conserved trait. However, research on teleost fishes has shown that this need not be the case, as these animals display a remarkable diversity in the ways that they determine sex. These different mechanisms, which include constitutive genetic mechanisms on sex chromosomes, polygenic constitutive mechanisms, environmental influences, hermaphroditism, and unisexuality have each originated numerous independent times in the teleosts. The evolutionary lability of sex determination, and the corresponding rapid rate of turn-over among different modes, makes the teleost clade an excellent model with which to test theories regarding the evolution of sex determining adaptations. Much of the plasticity in sex determination likely results from the dynamic teleost genome, and recent advances in fish genetics and genomics have revealed the role of gene and genome duplication in fostering emergence and turn-over of sex determining mechanisms. 2009 S. Karger AG, Basel.

Sex work involvement among women with long-term opioid injection drug dependence who enter opioid agonist treatment.

Science.gov (United States)

Marchand, Kirsten; Oviedo-Joekes, Eugenia; Guh, Daphne; Marsh, David C; Brissette, Suzanne; Schechter, Martin T

2012-01-25

Substitution with opioid-agonists (e.g., methadone) has shown to be an effective treatment for chronic long-term opioid dependency. Survival sex work, very common among injection drug users, has been associated with poor Opioid Agonist Treatment (OAT) engagement, retention and response. Therefore, this study was undertaken to determine factors associated with engaging in sex work among long-term opioid dependent women receiving OAT. Data from a randomized controlled trial, the North American Opiate Medication Initiative (NAOMI), conducted in Vancouver and Montreal (Canada) between 2005-2008, was analyzed. The NAOMI study compared the effectiveness of oral methadone to injectable diacetylmorphine or injectable hydromorphone, the last two on a double blind basis, over 12 months. A research team, independent of the clinic services, obtained outcome evaluations at baseline and follow-up (3, 6, 9, 12, 18 and 24 months). A total 53.6% of women reported engaging in sex work in at least one of the research visits. At treatment initiation, women who were younger and had fewer years of education were more likely to be engaged in sex work. The multivariate logistic generalized estimating equation regression analysis determined that psychological symptoms, and high illicit heroin and cocaine use correlated with women's involvement in sex work during the study period. After entering OAT, women using injection drugs and engaging in sex work represent a particularly vulnerable group showing poorer psychological health and a higher use of heroin and cocaine compared to women not engaging in sex work. These factors must be taken into consideration in the planning and provision of OAT in order to improve treatment outcomes. NCT00175357.

Sex work involvement among women with long-term opioid injection drug dependence who enter opioid agonist treatment

Directory of Open Access Journals (Sweden)

Marchand Kirsten

2012-01-01

Full Text Available Abstract Background Substitution with opioid-agonists (e.g., methadone has shown to be an effective treatment for chronic long-term opioid dependency. Survival sex work, very common among injection drug users, has been associated with poor Opioid Agonist Treatment (OAT engagement, retention and response. Therefore, this study was undertaken to determine factors associated with engaging in sex work among long-term opioid dependent women receiving OAT. Methods Data from a randomized controlled trial, the North American Opiate Medication Initiative (NAOMI, conducted in Vancouver and Montreal (Canada between 2005-2008, was analyzed. The NAOMI study compared the effectiveness of oral methadone to injectable diacetylmorphine or injectable hydromorphone, the last two on a double blind basis, over 12 months. A research team, independent of the clinic services, obtained outcome evaluations at baseline and follow-up (3, 6, 9, 12, 18 and 24 months. Results A total 53.6% of women reported engaging in sex work in at least one of the research visits. At treatment initiation, women who were younger and had fewer years of education were more likely to be engaged in sex work. The multivariate logistic generalized estimating equation regression analysis determined that psychological symptoms, and high illicit heroin and cocaine use correlated with women's involvement in sex work during the study period. Conclusions After entering OAT, women using injection drugs and engaging in sex work represent a particularly vulnerable group showing poorer psychological health and a higher use of heroin and cocaine compared to women not engaging in sex work. These factors must be taken into consideration in the planning and provision of OAT in order to improve treatment outcomes. Trial Registration NCT00175357.

Sex-dependent effects of cannabis-induced analgesia.

Science.gov (United States)

Cooper, Ziva D; Haney, Margaret

2016-10-01

Preclinical studies demonstrate that cannabinoid-mediated antinociceptive effects vary according to sex; it is unknown if these findings extend to humans. This retrospective analysis compared the analgesic, subjective and physiological effects of active cannabis (3.56-5.60% THC) and inactive cannabis (0.00% THC) in male (N=21) and female (N=21) cannabis smokers under double-blind, placebo-controlled conditions. Pain response was measured using the Cold-Pressor Test (CPT). Participants immersed their hand in cold water (4°C); times to report pain (pain sensitivity) and withdraw the hand (pain tolerance) were recorded. Subjective drug ratings were also measured. Among men, active cannabis significantly decreased pain sensitivity relative to inactive cannabis (pcannabis failed to decrease pain sensitivity relative to inactive. Active cannabis increased pain tolerance in both men women immediately after smoking (pcannabis also increased subjective ratings of cannabis associated with abuse liability ('Take again,' 'Liking,' 'Good drug effect'), drug strength, and 'High' relative to inactive in both men and women (pcannabis smokers, men exhibit greater cannabis-induced analgesia relative to women. These sex-dependent differences are independent of cannabis-elicited subjective effects associated with abuse-liability, which were consistent between men and women. As such, sex-dependent differences in cannabis's analgesic effects are an important consideration that warrants further investigation when considering the potential therapeutic effects of cannabinoids for pain relief. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Sex determination in the Hymenoptera

NARCIS (Netherlands)

Heimpel, George E.; de Boer, Jetske G.

2008-01-01

The dominant and ancestral mode of sex determination in the Hymenoptera is arrhenotokous parthenogenesis, in which diploid females develop from fertilized eggs and haploid males develop from unfertilized eggs. We discuss recent progress in the understanding of the genetic and cytoplasmic mechanisms

Effects of Elevated Ambient Temperature on Reproductive Outcomes and Offspring Growth Depend on Exposure Time

Directory of Open Access Journals (Sweden)

Huda Yahia Hamid

2012-01-01

Full Text Available Reproductive performance has been shown to be greatly affected by changes in environmental factors, such as temperature. However, it is also crucial to identify the particular stage of pregnancy that is most adversely affected by elevated ambient temperature. The aims of this study were to determine the effect on reproductive outcomes of exposure to elevated ambient temperature during different stages of pregnancy and to determine the effect of prenatal heat stress on offspring growth. Sixty pregnant rats were used in this study. The rats were divided equally into four groups as group 1 (control, group 2 (exposed to elevated temperature following implantation, group 3 (exposed to elevated temperature during pre- and periimplantation, and group 4 (exposed to elevated temperature during pre- and periimplantation and following implantation. Groups 3 and 4 had prolonged gestation periods, reduced litter sizes, and male-biased sex ratios. Moreover, the growth patterns of group 3 and 4 pups were adversely affected by prenatal exposure to elevated temperature. The differences between group 1 and group 3 and between group 1 and group 4 were highly significant. However, no significant differences were observed between groups 1 and 2 in the gestation length, sex ratios, and growth patterns. Thus, it can be concluded that exposure to elevated ambient temperature during pre- and periimplantation has stronger adverse effects on reproductive outcomes and offspring growth than postimplantation exposure.

Determination of Temperature-Dependent Stress State in Thin AlGaN Layer of AlGaN/GaN HEMT Heterostructures by Near-Resonant Raman Scattering

OpenAIRE

Yanli Liu; Xifeng Yang; Dunjun Chen; Hai Lu; Rong Zhang; Youdou Zheng

2015-01-01

The temperature-dependent stress state in the AlGaN barrier layer of AlGaN/GaN heterostructure grown on sapphire substrate was investigated by ultraviolet (UV) near-resonant Raman scattering. Strong scattering peak resulting from the A1(LO) phonon mode of AlGaN is observed under near-resonance condition, which allows for the accurate measurement of Raman shifts with temperature. The temperature-dependent stress in the AlGaN layer determined by the resonance Raman spectra is consistent with th...

Sex determination using free fetal DNA in early pregnancy: With the approach to sex linked recessive disorders

Directory of Open Access Journals (Sweden)

Amir Monfaredan

2017-03-01

Full Text Available Introduction: Prenatal diagnosis is testing for detection of diseases or conditions in a fetus or embryo before it is born. Most of prenatal diagnostic (PD techniques are invasive and done in late stages of pregnancy. Using fetal DNA in maternal blood for fetal sex determination in early pregnancy might help in management of X-linked genetic diseases. This study aimed to investigate the accuracy of sex determination using fetal DNA in maternal blood at 8-12 weeks of gestation. Methods: In this cross-sectional study, 30 pregnant women at 8-12 weeks of gestation were enrolled. The sex-determining region Y (SRY gene expression with the internal control (IC glyceraldehyde 3-phosphate dehydrogenase (GAPDH was investigated with quantitative real-time polymerase chain reaction (PCR using specific primers and probes. Results: Accuracy of sex determination with SRY gene expression in 8-12 weeks of pregnancy were 85%, 85%, 90% and 100% respectively. Conclusion: It seems that fetal sex determining using fetal DNA in maternal blood is a reliable method for early stage of pregnancy.

Comparative In silico Study of Sex-Determining Region Y (SRY) Protein Sequences Involved in Sex-Determining.

Science.gov (United States)

Vakili Azghandi, Masoume; Nasiri, Mohammadreza; Shamsa, Ali; Jalali, Mohsen; Shariati, Mohammad Mahdi

2016-04-01

The SRY gene (SRY) provides instructions for making a transcription factor called the sex-determining region Y protein. The sex-determining region Y protein causes a fetus to develop as a male. In this study, SRY of 15 spices included of human, chimpanzee, dog, pig, rat, cattle, buffalo, goat, sheep, horse, zebra, frog, urial, dolphin and killer whale were used for determine of bioinformatic differences. Nucleotide sequences of SRY were retrieved from the NCBI databank. Bioinformatic analysis of SRY is done by CLC Main Workbench version 5.5 and ClustalW (http:/www.ebi.ac.uk/clustalw/) and MEGA6 softwares. The multiple sequence alignment results indicated that SRY protein sequences from Orcinus orca (killer whale) and Tursiopsaduncus (dolphin) have least genetic distance of 0.33 in these 15 species and are 99.67% identical at the amino acid level. Homosapiens and Pantroglodytes (chimpanzee) have the next lowest genetic distance of 1.35 and are 98.65% identical at the amino acid level. These findings indicate that the SRY proteins are conserved in the 15 species, and their evolutionary relationships are similar.

Temperature dependence of magnetically dead layers in ferromagnetic thin-films

Directory of Open Access Journals (Sweden)

M. Tokaç

2017-11-01

Full Text Available Polarized neutron reflectometry has been used to study interface magnetism and magnetic dead layers in model amorphous CoFeB:Ta alloy thin-film multilayers with Curie temperatures tuned to be below room-temperature. This allows temperature dependent variations in the effective magnetic thickness of the film to be determined at temperatures that are a significant fraction of the Curie temperature, which cannot be achieved in the material systems used for spintronic devices. In addition to variation in the effective magnetic thickness due to compositional grading at the interface with the tantalum capping layer, the key finding is that at the interface between ferromagnetic film and GaAs(001 substrate local interfacial alloying creates an additional magnetic dead-layer. The thickness of this magnetic dead-layer is temperature dependent, which may have significant implications for elevated-temperature operation of hybrid ferromagnetic metal-semiconductor spintronic devices.

Temperature dependence of nuclear surface properties

International Nuclear Information System (INIS)

Campi, X.; Stringari, S.

1982-01-01

Thermal properties of nuclear surface are investigated in a semi-infinite medium. Explicit analytical expression are given for the temperature dependence of surface thickness, surface energy and surface free energy. In this model the temperature effects depend critically on the nuclear incompressibility and on the shape of the effective mass at the surface. To illustrate the relevance of these effects we made an estimate of the temperature dependence of the fission barrier height. (orig.)

Sex determination: insights from the silkworm

Indian Academy of Sciences (India)

2010-09-06

determination pathway that controls most sex-specific phenotypes, is a .... Sports and Culture, Government of Japan, grant-in-aid for Young. Scientists ... Berghammer A. J., Klingler M. and Wimmer E. A. 1999 A universal marker for ...

On the Temperature Dependence of Enzyme-Catalyzed Rates.

Science.gov (United States)

Arcus, Vickery L; Prentice, Erica J; Hobbs, Joanne K; Mulholland, Adrian J; Van der Kamp, Marc W; Pudney, Christopher R; Parker, Emily J; Schipper, Louis A

2016-03-29

One of the critical variables that determine the rate of any reaction is temperature. For biological systems, the effects of temperature are convoluted with myriad (and often opposing) contributions from enzyme catalysis, protein stability, and temperature-dependent regulation, for example. We have coined the phrase "macromolecular rate theory (MMRT)" to describe the temperature dependence of enzyme-catalyzed rates independent of stability or regulatory processes. Central to MMRT is the observation that enzyme-catalyzed reactions occur with significant values of ΔCp(‡) that are in general negative. That is, the heat capacity (Cp) for the enzyme-substrate complex is generally larger than the Cp for the enzyme-transition state complex. Consistent with a classical description of enzyme catalysis, a negative value for ΔCp(‡) is the result of the enzyme binding relatively weakly to the substrate and very tightly to the transition state. This observation of negative ΔCp(‡) has important implications for the temperature dependence of enzyme-catalyzed rates. Here, we lay out the fundamentals of MMRT. We present a number of hypotheses that arise directly from MMRT including a theoretical justification for the large size of enzymes and the basis for their optimum temperatures. We rationalize the behavior of psychrophilic enzymes and describe a "psychrophilic trap" which places limits on the evolution of enzymes in low temperature environments. One of the defining characteristics of biology is catalysis of chemical reactions by enzymes, and enzymes drive much of metabolism. Therefore, we also expect to see characteristics of MMRT at the level of cells, whole organisms, and even ecosystems.

Sex determination in honeybees: two separate mechanisms induce and maintain the female pathway

DEFF Research Database (Denmark)

Gempe, Tanja; Hasselmann, Martin; Schiøtt, Morten

2009-01-01

Organisms have evolved a bewildering diversity of mechanisms to generate the two sexes. The honeybee (Apis mellifera) employs an interesting system in which sex is determined by heterozygosity at a single locus (the Sex Determination Locus) harbouring the complementary sex determiner (csd) gene....... Bees heterozygous at Sex Determination Locus are females, whereas bees homozygous or hemizygous are males. Little is known, however, about the regulation that links sex determination to sexual differentiation. To investigate the control of sexual development in honeybees, we analyzed the functions...... and the regulatory interactions of genes involved in the sex determination pathway. We show that heterozygous csd is only required to induce the female pathway, while the feminizer (fem) gene maintains this decision throughout development. By RNAi induced knockdown we show that the fem gene is essential for entire...

Temperature-dependent cross sections for meson-meson nonresonant reactions in hadronic matter

International Nuclear Information System (INIS)

Zhang Yiping; Xu Xiaoming; Ge Huijun

2010-01-01

We present a potential of which the short-distance part is given by one gluon exchange plus perturbative one- and two-loop corrections and of which the large-distance part exhibits a temperature-dependent constant value. The Schroedinger equation with this temperature-dependent potential yields a temperature dependence of the mesonic quark-antiquark relative-motion wave function and of meson masses. The temperature dependence of the potential, the wave function and the meson masses brings about temperature dependence of cross sections for the nonresonant reactions ππ→ρρ for I=2, KK→K*K* for I=1, KK*→K*K* for I=1, πK→ρK* for I=3/2, πK*→ρK* for I=3/2, ρK→ρK* for I=3/2 and πK*→ρK for I=3/2. As the temperature increases, the rise or fall of peak cross sections is determined by the increased radii of initial mesons, the loosened bound states of final mesons, and the total-mass difference of the initial and final mesons. The temperature-dependent cross sections and meson masses are parametrized.

Mapping and validation of the major sex-determining region in Nile tilapia (Oreochromis niloticus L. Using RAD sequencing.

Directory of Open Access Journals (Sweden)

Christos Palaiokostas

Full Text Available Sex in Oreochromis niloticus (Nile tilapia is principally determined by an XX/XY locus but other genetic and environmental factors also influence sex ratio. Restriction Associated DNA (RAD sequencing was used in two families derived from crossing XY males with females from an isogenic clonal line, in order to identify Single Nucleotide Polymorphisms (SNPs and map the sex-determining region(s. We constructed a linkage map with 3,802 SNPs, which corresponded to 3,280 informative markers, and identified a major sex-determining region on linkage group 1, explaining nearly 96% of the phenotypic variance. This sex-determining region was mapped in a 2 cM interval, corresponding to approximately 1.2 Mb in the O. niloticus draft genome. In order to validate this, a diverse family (4 families; 96 individuals in total and population (40 broodstock individuals test panel were genotyped for five of the SNPs showing the highest association with phenotypic sex. From the expanded data set, SNPs Oni23063 and Oni28137 showed the highest association, which persisted both in the case of family and population data. Across the entire dataset all females were found to be homozygous for these two SNPs. Males were heterozygous, with the exception of five individuals in the population and two in the family dataset. These fish possessed the homozygous genotype expected of females. Progeny sex ratios (over 95% females from two of the males with the "female" genotype indicated that they were neomales (XX males. Sex reversal induced by elevated temperature during sexual differentiation also resulted in phenotypic males with the "female" genotype. This study narrows down the region containing the main sex-determining locus, and provides genetic markers tightly linked to this locus, with an association that persisted across the population. These markers will be of use in refining the production of genetically male O. niloticus for aquaculture.

Formal and informal sex education as determinants of premarital sexual behavior.

Science.gov (United States)

Spanier, G B

1976-01-01

Controversies exist regarding the effects of sex education in the schools and informal sex education obtained from parents, peers, the mass media, and other sources. Similarly, there is widespread interest in premarital sexual behavior, especially its determinants. This study presents several issues reflecting these concerns which have been the subject of much speculation but which have received little attention by researchers. The purpose of this study was to investigate--through the use of respondent reports--how formal and informal sex education influences premarital sexual behavior during college. A national probability sample of 1177 college students was studied using face-to-face interviews with approximately equal numbers of males and females. These interviews, which were conducted for the Institute for Sex Research, included questions about past and present sexual involvement and other attitudinal, behavioral and background variables. Accordingly, the data about sexual behavior and attitudes are based on the interviewees' self-reports. Indices were created which operationalized independent variables such as familial sexual conservatism, exposure to eroticism, perceived sex knowledge, and sexual exposure and assault during childhood and adolescence. Individual items reflecting childhood sex play, masturbation, current religiosity, religiosity while growing up, social class, sources of sex information, sex education in classrooms, and high school and college dating were used. The dependent variable, premarital sociosexual involvement, is a composite measure of incidence and prevalence of premarital heterosexual involvement which meets Guttman scaling criteria. An Automatic Interaction Detector analysis was used to determine the relative influences of reported sexualization variables on premarital sexual behavior. Major findings can be summarized as follows: Heterosexual behavior progresses in stepwise fashion from elementary to advanced levels of involvement

Temperature dependence of Brewster's angle.

Science.gov (United States)

Guo, Wei

2018-01-01

In this work, a dielectric at a finite temperature is modeled as an ensemble of identical atoms moving randomly around where they are trapped. Light reflection from the dielectric is then discussed in terms of atomic radiation. Specific calculation demonstrates that because of the atoms' thermal motion, Brewster's angle is, in principle, temperature-dependent, and the dependence is weak in the low-temperature limit. What is also found is that the Brewster's angle is nothing but a result of destructive superposition of electromagnetic radiation from the atoms.

Drosophila mitotypes determine developmental time in a diet and temperature dependent manner.

Science.gov (United States)

Towarnicki, Samuel G; Ballard, J William O

2017-07-01

It is well known that specific mitochondrial (mt) DNA mutations can reduce organismal fitness and influence mitochondrial-nuclear interactions. However, determining specific mtDNA mutations that are beneficial has been elusive. In this study, we vary the diet and environmental temperature to study larval development time of two Drosophila melanogaster mitotypes (Alstonville and Dahomey), in two nuclear genetic backgrounds, and investigate developmental differences through weight, feeding rate, and movement. To manipulate the diet, we utilize the nutritional geometric framework to manipulate isocaloric diets of differing macronutrient ratios (1:2 and 1:16 protein: carbohydrate (P:C) ratios) and raise flies at three temperatures (19°C, 23°C and 27°C). Larvae with Dahomey mtDNA develop more slowly than Alstonville when fed the 1:2 P:C diet at all temperatures and developed more quickly when fed the 1:16 P:C diet at 23°C and 27°C. We determined that Dahomey larvae eat more, move less, and weigh more than Alstonville larvae when raised on the 1:16 P:C diet and that these physiological responses are modified by temperature. We suggest that 1 (or more) of 4 mtDNA changes is likely responsible for the observed effects and posit the mtDNA changes moderate a physiological trade-off between consumption and foraging. Copyright © 2017 Elsevier Ltd. All rights reserved.

Angular dependence of coercivity with temperature in Co-based nanowires

Energy Technology Data Exchange (ETDEWEB)

Bran, C., E-mail: cristina.bran@icmm.csic.es [Institute of Materials Science of Madrid, CSIC, 28049 Madrid (Spain); Espejo, A.P. [Departamento de Física, Universidad de Santiago de Chile (USACH) and Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avenida Ecuador 3493, 9170124 Santiago (Chile); Palmero, E.M. [Institute of Materials Science of Madrid, CSIC, 28049 Madrid (Spain); Escrig, J. [Departamento de Física, Universidad de Santiago de Chile (USACH) and Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avenida Ecuador 3493, 9170124 Santiago (Chile); Vázquez, M. [Institute of Materials Science of Madrid, CSIC, 28049 Madrid (Spain)

2015-12-15

The magnetic behavior of arrays of Co and CoFe nanowire arrays has been measured in the temperature range between 100 and 300 K. We have paid particular attention to the angular dependence of magnetic properties on the applied magnetic field orientation. The experimental angular dependence of coercivity has been modeled according to micromagnetic analytical calculations, and we found that the propagation of a transversal domain wall mode gives the best fitting with experimental observations. That reversal mode holds in the whole measuring temperature range, for nanowires with different diameters and crystalline structure. Moreover, the quantitative strength of the magnetocrystalline anisotropy and its magnetization easy axis are determined to depend on the crystalline structure and nanowires diameter. The evolution of the magnetocrystalline anisotropy with temperature for nanowires with different composition gives rise to an opposite evolution of coercivity with increasing temperature: it decreases for CoFe while it increases for Co nanowire arrays.

Modeling the temperature dependence of thermophysical properties: Study on the effect of temperature dependence for RFA.

Science.gov (United States)

Watanabe, Hiroki; Kobayashi, Yo; Hashizume, Makoto; Fujie, Masakatsu G

2009-01-01

Radio frequency ablation (RFA) has increasingly been used over the past few years and RFA treatment is minimally invasive for patients. However, it is difficult for operators to control the precise formation of coagulation zones due to inadequate imaging modalities. With this in mind, an ablation system using numerical simulation to analyze the temperature distribution of the organ is needed to overcome this deficiency. The objective of our work is to develop a temperature dependent thermophysical liver model. First, an overview is given of the development of the thermophysical liver model. Second, a simulation to evaluate the effect of temperature dependence of the thermophysical properties of the liver is explained. Finally, the result of the simulation, which indicated that the temperature dependence of thermophysical properties accounts for temperature differences influencing the accuracy of RFA treatment is described.

How is sex determined in insects?

Indian Academy of Sciences (India)

gan's student Calvin Bridges formulated his classic balance theory of sex determination in ... affect not only specific traits but also the entire sexual fate of an individual. ... the decision whether to become male or female is conveyed very early in ...

Single locus complementary sex determination in Hymenoptera : an "unintelligent" design?

NARCIS (Netherlands)

Wilgenburg, Ellen van; Driessen, Gerard; Beukeboom, Leo W.

2006-01-01

The haplodiploid sex determining mechanism in Hymenoptera (males are haploid, females are diploid) has played an important role in the evolution of this insect order. In Hymenoptera sex is usually determined by a single locus, heterozygotes are female and hemizygotes are male. Under inbreeding,

Single locus complementary sex determination in Hymenoptera: an "unintelligent" design?

NARCIS (Netherlands)

van Wilgenburg, E.; Driessen, G.J.J.; Beukeboom, L.W.

2006-01-01

The haplodiploid sex determining mechanism in Hymenoptera (males are haploid, females are diploid) has played an important role in the evolution of this insect order. In Hymenoptera sex is usually determined by a single locus, heterozygotes are female and hemizygotes are male. Under inbreeding,

Hysteresis and Temperature Dependency of Moisture Sorption – New Measurements

DEFF Research Database (Denmark)

Rode, Carsten; Hansen, Kurt Kielsgaard

2011-01-01

measurements of hysteresis and temperature dependency of the moisture sorption characteristics of three different porous building materials: aerated concrete, cement paste and spruce. Scanning curves are measured for all three materials where periods with adsorption and desorption interrupt each other...... intermittently. For one of the materials, aerated concrete, the sorption curves are determined at three different temperatures....

Sex-dependent expression of caveolin 1 in response to sex steroid hormones is closely associated with development of obesity in rats.

Directory of Open Access Journals (Sweden)

Rajib Mukherjee

Full Text Available Caveolin-1 (CAV1 is a conserved group of structural membrane proteins that form special cholesterol and sphingolipid-rich compartments, especially in adipocytes. Recently, it has been reported that CAV1 is an important target protein in sex hormone-dependent regulation of various metabolic pathways, particularly in cancer and diabetes. To clarify distinct roles of CAV1 in sex-dependent obesity development, we investigated the effects of high fat diet (HFD and sex steroid hormones on CAV1 expression in adipose tissues of male and female rats. Results of animal experiments revealed that estrogen (17-β-estradiol, E2 and androgen (dihydrotestosterone, DHT had opposite effects on body weight gain as well as on the regulation of CAV1, hormone sensitive lipase (HSL and uncoupling protein 1 (UCP1 in adipose tissues. Furthermore, sex hormone receptors and aromatase were differentially expressed in a sex-dependent manner in response to E2 and DHT treatments. In vivo data were confirmed using 3T3-L1 and HIB1B cell lines, where Cav1 knock down stimulated lipogenesis but suppressed sex hormone receptor signaling proteins. Most importantly, co-immunoprecipitation enabled the identification of previously unrecognized CAV1-interacting mitochondrial or lipid oxidative pathway proteins in adipose tissues. Taken together, current data showed that CAV1 may play important preventive role in the development of obesity, with more prominent effects in females, and proved to be an important target protein for the hormonal regulation of adipose tissue metabolism by manipulating sex hormone receptors and mitochondrial oxidative pathways. Therefore, we can report, for the first time, the molecular mechanism underlying the effects of sex steroid hormones in the sex-dimorphic regulation of CAV1.

Density-dependent sex ratio and sex-specific preference for host traits in parasitic bat flies.

Science.gov (United States)

Szentiványi, Tamara; Vincze, Orsolya; Estók, Péter

2017-08-29

Deviation of sex ratios from unity in wild animal populations has recently been demonstrated to be far more prevalent than previously thought. Ectoparasites are prominent examples of this bias, given that their sex ratios vary from strongly female- to strongly male-biased both among hosts and at the metapopulation level. To date our knowledge is very limited on how and why these biased sex ratios develop. It was suggested that sex ratio and sex-specific aggregation of ectoparasites might be shaped by the ecology, behaviour and physiology of both hosts and their parasites. Here we investigate a highly specialised, hematophagous bat fly species with strong potential to move between hosts, arguably limited inbreeding effects, off-host developmental stages and extended parental care. We collected a total of 796 Nycteribia kolenatii bat flies from 147 individual bats using fumigation and subsequently determined their sex. We report a balanced sex ratio at the metapopulation level and a highly variable sex ratio among infrapopulations ranging from 100% male to 100% female. We show that infrapopulation sex ratio is not random and is highly correlated with infrapopulation size. Sex ratio is highly male biased in small and highly female biased in large infrapopulations. We show that this pattern is most probably the result of sex-specific preference in bat flies for host traits, most likely combined with a higher mobility of males. We demonstrate that female bat flies exert a strong preference for high host body condition and female hosts, while the distribution of males is more even. Our results suggest that locally biased sex ratios can develop due to sex-specific habitat preference of parasites. Moreover, it is apparent that the sex of both hosts and parasites need to be accounted for when a better understanding of host-parasite systems is targeted.

Comparative In silico Study of Sex-Determining Region Y (SRY Protein Sequences Involved in Sex-Determining

Directory of Open Access Journals (Sweden)

Masoume Vakili Azghandi

2016-05-01

Full Text Available Background: The SRY gene (SRY provides instructions for making a transcription factor called the sex-determining region Y protein. The sex-determining region Y protein causes a fetus to develop as a male. In this study, SRY of 15 spices included of human, chimpanzee, dog, pig, rat, cattle, buffalo, goat, sheep, horse, zebra, frog, urial, dolphin and killer whale were used for determine of bioinformatic differences. Methods: Nucleotide sequences of SRY were retrieved from the NCBI databank. Bioinformatic analysis of SRY is done by CLC Main Workbench version 5.5 and ClustalW (http:/www.ebi.ac.uk/clustalw/ and MEGA6 softwares. Results: The multiple sequence alignment results indicated that SRY protein sequences from Orcinus orca (killer whale and Tursiopsaduncus (dolphin have least genetic distance of 0.33 in these 15 species and are 99.67% identical at the amino acid level. Homosapiens and Pantroglodytes (chimpanzee have the next lowest genetic distance of 1.35 and are 98.65% identical at the amino acid level. Conclusion: These findings indicate that the SRY proteins are conserved in the 15 species, and their evolutionary relationships are similar.

Liquid-filled ionization chamber temperature dependence

Energy Technology Data Exchange (ETDEWEB)

Franco, L. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain)]. E-mail: luciaff@usc.es; Gomez, F. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Iglesias, A. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Pardo, J. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Pazos, A. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Pena, J. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Zapata, M. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain)

2006-05-10

Temperature and pressure corrections of the read-out signal of ionization chambers have a crucial importance in order to perform high-precision absolute dose measurements. In the present work the temperature and pressure dependences of a sealed liquid isooctane filled ionization chamber (previously developed by the authors) for radiotherapy applications have been studied. We have analyzed the thermal response of the liquid ionization chamber in a {approx}20 deg. C interval around room temperature. The temperature dependence of the signal can be considered linear, with a slope that depends on the chamber collection electric field. For example, a relative signal slope of 0.27x10{sup -2}K{sup -1} for an operation electric field of 1.67x10{sup 6}Vm{sup -1} has been measured in our detector. On the other hand, ambient pressure dependence has been found negligible, as expected for liquid-filled chambers. The thermal dependence of the liquid ionization chamber signal can be parametrized within the Onsager theory on initial recombination. Considering that changes with temperature of the detector response are due to variations in the free ion yield, a parametrization of this dependence has been obtained. There is a good agreement between the experimental data and the theoretical model from the Onsager framework.

Accuracy and reliability in sex determination from skulls: a comparison of Fordisc® 3.0 and the discriminant function analysis.

Science.gov (United States)

Guyomarc'h, Pierre; Bruzek, Jaroslav

2011-05-20

Identification in forensic anthropology and the definition of a biological profile in bioarchaeology are essential to each of those fields and use the same methodologies. Sex, age, stature and ancestry can be conclusive or dispensable, depending on the field. The Fordisc(®) 3.0 computer program was developed to aid in the identification of the sex, stature and ancestry of skeletal remains by exploiting the Forensic Data Bank (FDB) and computing discriminant function analyses (DFAs). Although widely used, this tool has been recently criticised, principally when used to determine ancestry. Two sub-samples of individuals of known sex were drawn from French (n=50) and Thai (n=91) osteological collections and used to assess the reliability of sex determination using Fordisc(®) 3.0 with 12 cranial measurements. Comparisons were made using the whole FDB as well as using select groups, taking into account the posterior and typicality probabilities. The results of Fordisc(®) 3.0 vary between 52.2% and 77.8% depending on the options and groups selected. Tests of published discriminant functions and the computation of specific DFA were performed in order to discuss the applicability of this software and, overall, to question the pertinence of the use of DFA and linear distances in sex determination, in light of the huge cranial morphological variability. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Temperature Dependence in Heterogeneous Nucleation with Application to the Direct Determination of Cluster Energy on Nearly Molecular Scale.

Science.gov (United States)

McGraw, Robert L; Winkler, Paul M; Wagner, Paul E

2017-12-04

A re-examination of measurements of heterogeneous nucleation of water vapor on silver nanoparticles is presented here using a model-free framework that derives the energy of critical cluster formation directly from measurements of nucleation probability. Temperature dependence is correlated with cluster stabilization by the nanoparticle seed and previously found cases of unusual increasing nucleation onset saturation ratio with increasing temperature are explained. A necessary condition for the unusual positive temperature dependence is identified, namely that the critical cluster be more stable, on a per molecule basis, than the bulk liquid to exhibit the effect. Temperature dependence is next examined in the classical Fletcher model, modified here to make the energy of cluster formation explicit in the model.  The contact angle used in the Fletcher model is identified as the microscopic contact angle, which can be directly obtained from heterogeneous nucleation experimental data by a recently developed analysis method. Here an equivalent condition, increasing contact angle with temperature, is found necessary for occurrence of unusual temperature dependence. Our findings have immediate applications to atmospheric particle formation and nanoparticle detection in condensation particle counters (CPCs).

Sex determination in gibbons of genus Nomascus using non-invasive method

Directory of Open Access Journals (Sweden)

Petra Bolechová

2016-01-01

Full Text Available Gibbons of the genus Nomascus have a strong sexual dimorphism and dichromatism. As they mature, both sexes develop sex-specific pelage colour. In combination with physical similarities in the genitalia with both sexes, there are problems with determining the sex of young individuals compared to other genus of gibbons. This is a pilot study applying a multiplex polymerase chain reactions based on a non-invasive method for sex determination of gibbons. The study was conducted on 22 faecal samples from gibbons of the genus Nomascus. The animals were monitored by staff so that the samples were identified correctly and each sample was collected immediately after the defecation. Results confirmed the sex in all adult and juvenile animals with known sex; and 2 females and 5 males in juveniles were determined with unknown sex. The results of direct examination completely corresponded with the PCR results. The PCR reaction with template DNA isolated from faecal material required BSA usage, however, we observed the occurrence of nonspecific fragments. This did not affect the reliability of our results and we confirmed the usability of this method for this genus.

Sex determination using the Probabilistic Sex Diagnosis (DSP: Diagnose Sexuelle Probabiliste) tool in a virtual environment.

Science.gov (United States)

Chapman, Tara; Lefevre, Philippe; Semal, Patrick; Moiseev, Fedor; Sholukha, Victor; Louryan, Stéphane; Rooze, Marcel; Van Sint Jan, Serge

2014-01-01

The hip bone is one of the most reliable indicators of sex in the human body due to the fact it is the most dimorphic bone. Probabilistic Sex Diagnosis (DSP: Diagnose Sexuelle Probabiliste) developed by Murail et al., in 2005, is a sex determination method based on a worldwide hip bone metrical database. Sex is determined by comparing specific measurements taken from each specimen using sliding callipers and computing the probability of specimens being female or male. In forensic science it is sometimes not possible to sex a body due to corpse decay or injury. Skeletalization and dissection of a body is a laborious process and desecrates the body. There were two aims to this study. The first aim was to examine the accuracy of the DSP method in comparison with a current visual sexing method on sex determination. A further aim was to see if it was possible to virtually utilise the DSP method on both the hip bone and the pelvic girdle in order to utilise this method for forensic sciences. For the first part of the study, forty-nine dry hip bones of unknown sex were obtained from the Body Donation Programme of the Université Libre de Bruxelles (ULB). A comparison was made between DSP analysis and visual sexing on dry bone by two researchers. CT scans of bones were then analysed to obtain three-dimensional (3D) virtual models and the method of DSP was analysed virtually by importing the models into a customised software programme called lhpFusionBox which was developed at ULB. The software enables DSP distances to be measured via virtually-palpated bony landmarks. There was found to be 100% agreement of sex between the manual and virtual DSP method. The second part of the study aimed to further validate the method by analysing thirty-nine supplementary pelvic girdles of known sex blind. There was found to be a 100% accuracy rate further demonstrating that the virtual DSP method is robust. Statistically significant differences were found in the identification of sex

Economic dependence and unprotected sex: the role of sexual assertiveness among young urban mothers.

Science.gov (United States)

Biello, Katie Brooks; Sipsma, Heather L; Ickovics, Jeannette R; Kershaw, Trace

2010-05-01

In the USA, sexual intercourse is the leading route of human immunodeficiency virus transmission among women, primarily through their main partner. Because male condom use is not directly under a woman's control, gender inequalities may help shape this sexual risk behavior. To examine this association, data came from follow-up interviews of young, primarily minority, pregnant women enrolled in a prospective, randomized controlled trial. Specifically, we aimed to determine the relationship between economic dependence on a male partner and condom use, and to establish whether this relationship was mediated by sexual assertiveness. Overall, 28% of women reported being economically dependent on a male partner. Young women dependent on a male partner were 1.6 times more likely to report not using a condom at last sex than women not dependent on their partner (95% confidence interval = 1.11-2.32; p = 0.01). Sexual assertiveness mediated the relationship between economic dependence and condom use (Sobel = 2.05, p = 0.04). Coupled with past research, this study supports the premise that sexual behaviors may be rooted in a complex web of social determinants. Addressing gender inequalities in contextual factors may promote healthier decisions within sexual relationships.

Temperature and boron dependencies of buckling and radial reflector saving for VVER lattices

International Nuclear Information System (INIS)

Alvarez, C.

1990-01-01

The temperature and boron dependencies of buckling and radial reflectors savings are analyzed in this paper on the basis of the results from the calculations ZR-6M critical assembly. These dependencies are related to the physical behavior of temperature and boron reactivity coefficients for the cores of VVER-type critical facilities. As a byproduct, the parameter was also investigated and its dependence on water density was determined

Sex-dependent differences in voluntary physical activity.

Science.gov (United States)

Rosenfeld, Cheryl S

2017-01-02

Numbers of overweight and obese individuals are increasing in the United States and globally, and, correspondingly, the associated health care costs are rising dramatically. More than one-third of children are currently considered obese with a predisposition to type 2 diabetes, and it is likely that their metabolic conditions will worsen with age. Physical inactivity has also risen to be the leading cause of many chronic, noncommunicable diseases (NCD). Children are more physically inactive now than they were in past decades, which may be due to intrinsic and extrinsic factors. In rodents, the amount of time engaged in spontaneous activity within the home cage is a strong predictor of later adiposity and weight gain. Thus, it is important to understand primary motivators stimulating physical activity (PA). There are normal sex differences in PA levels in rodents and humans. The perinatal environment can induce sex-dependent differences in PA disturbances. This Review considers the current evidence for sex differences in PA in rodents and humans. The rodent studies showing that early exposure to environmental chemicals can shape later adult PA responses are discussed. Next, whether there are different motivators stimulating exercise in male vs. female humans are examined. Finally, the brain regions, genes, and pathways that modulate PA in rodents, and possibly by translation in humans, are described. A better understanding of why each sex remains physically active through the life span could open new avenues for preventing and treating obesity in children and adults. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Temperature dependence of three-body ion-molecule reactions

International Nuclear Information System (INIS)

Boehringer, H.; Arnold, F.

1983-01-01

The temperature dependence of the ion-molecule association reactions (i) N 2 + + N 2 + M → N 4 + + M (M=N 2 , He), (ii) O 2 + + O 2 + M → O 4 + + M (M=O 2 , He) and (iii) He + + 2He → He 2 + + He have been studied over an extended temperature range to temperatures as low as 30K with a recently constructed liquid helium-cooled ion drift tube. Over most of the temperature range the threebody reaction rate coefficients show an inverse temperature dependence proportional to Tsup(-n) with n in the range 0.6 to 2.9. This temperature dependence is quite consistent with current theories of ion molecule association. At low temperatures, however, a deviation from the Tsup(-n) dependence was observed for the association reactions (ii). For reactions (i) different temperature dependences were obtained for N 2 and He third bodies indicating an additional temperature dependence of the collisional stabilisation process. (Authors)

Sex differences in the effects of juvenile and adult diet on age-dependent reproductive effort.

Science.gov (United States)

Houslay, T M; Hunt, J; Tinsley, M C; Bussière, L F

2015-05-01

Sexual selection should cause sex differences in patterns of resource allocation. When current and future reproductive effort trade off, variation in resource acquisition might further cause sex differences in age-dependent investment, or in sensitivity to changes in resource availability over time. However, the nature and prevalence of sex differences in age-dependent investment remain unclear. We manipulated resource acquisition at juvenile and adult stages in decorated crickets, Gryllodes sigillatus, and assessed effects on sex-specific allocation to age-dependent reproductive effort (calling in males, fecundity in females) and longevity. We predicted that the resource and time demands of egg production would result in relatively consistent female strategies across treatments, whereas male investment should depend sharply on diet. Contrary to expectations, female age-dependent reproductive effort diverged substantially across treatments, with resource-limited females showing much lower and later investment in reproduction; the highest fecundity was associated with intermediate lifespans. In contrast, long-lived males always signalled more than short-lived males, and male age-dependent reproductive effort did not depend on diet. We found consistently positive covariance between male reproductive effort and lifespan, whereas diet altered this covariance in females, revealing sex differences in the benefits of allocation to longevity. Our results support sex-specific selection on allocation patterns, but also suggest a simpler alternative: males may use social feedback to make allocation decisions and preferentially store resources as energetic reserves in its absence. Increased calling effort with age therefore could be caused by gradual resource accumulation, heightened mortality risk over time, and a lack of feedback from available mates. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary

Calmodulin-dependent nuclear import of HMG-box family nuclear factors: importance of the role of SRY in sex reversal.

Science.gov (United States)

Kaur, Gurpreet; Delluc-Clavieres, Aurelie; Poon, Ivan K H; Forwood, Jade K; Glover, Dominic J; Jans, David A

2010-08-15

The HMG (high-mobility group)-box-containing chromatin-remodelling factor SRY (sex-determining region on the Y chromosome) plays a key role in sex determination. Its role in the nucleus is critically dependent on two NLSs (nuclear localization signals) that flank its HMG domain: the C-terminally located 'beta-NLS' that mediates nuclear transport through Impbeta1 (importin beta1) and the N-terminally located 'CaM-NLS' which is known to recognize the calcium-binding protein CaM (calmodulin). In the present study, we examined a number of missense mutations in the SRY CaM-NLS from human XY sex-reversed females for the first time, showing that they result in significantly reduced nuclear localization of GFP (green fluorescent protein)-SRY fusion proteins in transfected cells compared with wild-type. The CaM antagonist CDZ (calmidazolium chloride) was found to significantly reduce wild-type SRY nuclear accumulation, indicating dependence of SRY nuclear import on CaM. Intriguingly, the CaM-NLS mutants were all resistant to CDZ's effects, implying a loss of interaction with CaM, which was confirmed by direct binding experiments. CaM-binding/resultant nuclear accumulation was the only property of SRY found to be impaired by two of the CaM-NLS mutations, implying that inhibition of CaM-dependent nuclear import is the basis of sex reversal in these cases. Importantly, the CaM-NLS is conserved in other HMG-box-domain-containing proteins such as SOX-2, -9, -10 and HMGN1, all of which were found for the first time to rely on CaM for optimal nuclear localization. CaM-dependent nuclear translocation is thus a common mechanism for this family of important transcription factors.

Sex-Dependent Effects of Developmental Lead Exposure on the Brain

Science.gov (United States)

Singh, Garima; Singh, Vikrant; Sobolewski, Marissa; Cory-Slechta, Deborah A.; Schneider, Jay S.

2018-01-01

The role of sex as an effect modifier of developmental lead (Pb) exposure has until recently received little attention. Lead exposure in early life can affect brain development with persisting influences on cognitive and behavioral functioning, as well as, elevated risks for developing a variety of diseases and disorders in later life. Although both sexes are affected by Pb exposure, the incidence, manifestation, and severity of outcomes appears to differ in males and females. Results from epidemiologic and animal studies indicate significant effect modification by sex, however, the results are not consistent across studies. Unfortunately, only a limited number of human epidemiological studies have included both sexes in independent outcome analyses limiting our ability to draw definitive conclusions regarding sex-differentiated outcomes. Additionally, due to various methodological differences across studies, there is still not a good mechanistic understanding of the molecular effects of lead on the brain and the factors that influence differential responses to Pb based on sex. In this review, focused on prenatal and postnatal Pb exposures in humans and animal models, we discuss current literature supporting sex differences in outcomes in response to Pb exposure and explore some of the ideas regarding potential molecular mechanisms that may contribute to sex-related differences in outcomes from developmental Pb exposure. The sex-dependent variability in outcomes from developmental Pb exposure may arise from a combination of complex factors, including, but not limited to, intrinsic sex-specific molecular/genetic mechanisms and external risk factors including sex-specific responses to environmental stressors which may act through shared epigenetic pathways to influence the genome and behavioral output. PMID:29662502

Sex-Dependent Effects of Developmental Lead Exposure on the Brain

Directory of Open Access Journals (Sweden)

Garima Singh

2018-03-01

Full Text Available The role of sex as an effect modifier of developmental lead (Pb exposure has until recently received little attention. Lead exposure in early life can affect brain development with persisting influences on cognitive and behavioral functioning, as well as, elevated risks for developing a variety of diseases and disorders in later life. Although both sexes are affected by Pb exposure, the incidence, manifestation, and severity of outcomes appears to differ in males and females. Results from epidemiologic and animal studies indicate significant effect modification by sex, however, the results are not consistent across studies. Unfortunately, only a limited number of human epidemiological studies have included both sexes in independent outcome analyses limiting our ability to draw definitive conclusions regarding sex-differentiated outcomes. Additionally, due to various methodological differences across studies, there is still not a good mechanistic understanding of the molecular effects of lead on the brain and the factors that influence differential responses to Pb based on sex. In this review, focused on prenatal and postnatal Pb exposures in humans and animal models, we discuss current literature supporting sex differences in outcomes in response to Pb exposure and explore some of the ideas regarding potential molecular mechanisms that may contribute to sex-related differences in outcomes from developmental Pb exposure. The sex-dependent variability in outcomes from developmental Pb exposure may arise from a combination of complex factors, including, but not limited to, intrinsic sex-specific molecular/genetic mechanisms and external risk factors including sex-specific responses to environmental stressors which may act through shared epigenetic pathways to influence the genome and behavioral output.

Temperature dependence of surface nanobubbles

NARCIS (Netherlands)

Berkelaar, R.P.; Seddon, James Richard Thorley; Zandvliet, Henricus J.W.; Lohse, Detlef

2012-01-01

The temperature dependence of nanobubbles was investigated experimentally using atomic force microscopy. By scanning the same area of the surface at temperatures from 51 °C to 25 °C it was possible to track geometrical changes of individual nanobubbles as the temperature was decreased.

COMPLEMENTARY SEX DETERMINATION IN HYMENOPTERAN PARASITOIDS AND ITS IMPLICATIONS FOR BIOLOGICAL CONTROL

Institute of Scientific and Technical Information of China (English)

WUZhishan; KeithR.Hopper; PaulJ.Ode; RogerW.Fuester; CHENJia-hua; GeorgeE.Heimpel

2003-01-01

In haplodiploid Hymenoptera, unfertilized eggs produce haploid males while fertilized eggs lead to diploid females under most circumstances. Diploid males can also be produced from fertilization under a system of sex determination known as complementary sex determination (CSD). Under single-locus CSD, sex is determined by multiple alleles at a single sex locus. Individuals heterozygous at the sex locus are female while hemizygous and homozygous individuals develop as haploid and diploid males, respectively. In multiple-locus CSD, two or more loci, each with two or more alleles, determine sex. Diploid individuals are female if one or more sex loci are het-erozygous, while a diploid is male only if homozygous at all sex loci. Diploid males are known to occur in 43 hym-enopteran species and single-locus CSD has been demonstrated in 22 of these species. Diploid males are either developmentally inviable or sterile, so their production constitutes a genetic load. Because diploid male production is more likely under inbreeding, CSD is a form of inbreeding depression. It is crucial to preserve the diversity of sex alleles and reduce the loss of genetic variation in biological control. In the parasitoid species with single-locus CSD, certain precautionary procedures can prevent negative effects of single-locus CSD on biological control.

Impacts of temperature and crowding on sex ratio, fecundity and Wolbachia infection intensity in the copepod, Mesocyclops thermocyclopoides.

Science.gov (United States)

Wiwatanaratanabutr, Itsanun; Grandjean, Frederic

2016-11-01

Wolbachia are a group of intracellular bacteria that cause reproductive alterations in arthropods. Here, we describe the effects of two environmental factors (crowding and temperature) on phenotypic expression of feminization, the host's fecundity and Wolbachia infection intensity among life cycle stages in the naturally Wolbachia-infected copepod, Mesocyclops thermocyclopoides. The copepod was first found to be co-infected with Wolbachia A- and B-supergroups Wolbachia strains based on wsp primers. The relative Wolbachia infection intensity within individuals was determined using quantitative real-time PCR and was significantly higher in the B-supergroup than in the A-supergroup. Experimental results of temperature effect on bacterial density in each developmental stage revealed a significant decrease in Wolbachia infection intensity following exposure to high temperature (37°C) in both sexes and implied that Wolbachia might survive in room temperature (25°C) better than in high temperature. Experimental results of crowding effects on Wolbachia infection intensity suggested a negative correlation between copepod nauplii and Wolbachia infection intensity. No effect of rearing temperature on the sex ratio was reported although the fecundity was significantly decreased by high temperature. The results showed that Wolbachia infection intensity to be correlated with crowding conditions and was decreased following exposure of elevated temperature. Copyright © 2016 Elsevier Inc. All rights reserved.

Temperature and boron dependencies of buckling and radial reflector savings for VVER lattices

International Nuclear Information System (INIS)

Alvarez, C.

1990-01-01

The temperature and boron dependencies of buckling and radial reflector savings are analyzed in this paper on the basis of the results from the calculations for the ZR-6M critical assembly. These dependencies are related to he physical behaviour of temperature and boron reactivity coefficients for the cores of VVER-type critical facilities. As a byproduct, the dp/dBg 2 parameter was also investigated and its dependence on water density was determined

Sex and PRNP genotype determination in preimplantation caprine embryos.

Science.gov (United States)

Guignot, F; Perreau, C; Cavarroc, C; Touzé, J-L; Pougnard, J-L; Dupont, F; Beckers, J-F; Rémy, B; Babilliot, J-M; Bed'Hom, B; Lamorinière, J M; Mermillod, P; Baril, G

2011-08-01

The objective of this study was to test the accuracy of genotype diagnosis after whole amplification of DNA extracted from biopsies obtained by trimming goat embryos and to evaluate the viability of biopsied embryos after vitrification/warming and transfer. Whole genome amplification (WGA) was performed using Multiple Displacement Amplification (MDA). Sex and prion protein (PRNP) genotypes were determined. Sex diagnosis was carried out by PCR amplification of ZFX/ZFY and Y chromosome-specific sequences. Prion protein genotype determination was performed on codons 142, 154, 211, 222 and 240. Embryos were collected at day 7 after oestrus and biopsied either immediately after collection (blastocysts and expanded blastocysts) or after 24 h of in vitro culture (compacted morulae). Biopsied embryos were frozen by vitrification. Vitrified whole embryos were kept as control. DNA of biopsies was extracted and amplified using MDA. Sex diagnosis was efficient for 97.4% of biopsies and PRNP genotyping was determined in 78.7% of biopsies. After embryo transfer, no significant difference was observed in kidding rate between biopsied and vitrified control embryos, whereas embryo survival rate was different between biopsied and whole vitrified embryos (p = 0.032). At birth, 100% of diagnosed sex and 98.2% of predetermined codons were correct. Offspring PRNP profiles were in agreement with parental genotype. Whole genome amplification with MDA kit coupled with sex diagnosis and PRNP genotype predetermination are very accurate techniques to genotype goat embryos before transfer. These novel results allow us to plan selection of scrapie-resistant genotypes and kid sex before transfer of cryopreserved embryo. © 2010 Blackwell Verlag GmbH.

Temperature dependency in motor skill learning.

Science.gov (United States)

Immink, Maarten A; Wright, David L; Barnes, William S

2012-01-01

The present study investigated the role of temperature as a contextual condition for motor skill learning. Precision grip task training occurred while forearm cutaneous temperature was either heated (40-45 °C) or cooled (10-15 °C). At test, temperature was either reinstated or changed. Performance was comparable between training conditions while at test, temperature changes decreased accuracy, especially after hot training conditions. After cold training, temperature change deficits were only evident when concurrent force feedback was presented. These findings are the first evidence of localized temperature dependency in motor skill learning in humans. Results are not entirely accounted for by a context-dependent memory explanation and appear to represent an interaction of neuromuscular and sensory processes with the temperature present during training and test.

Guardian small RNAs and sex determination.

Science.gov (United States)

Katsuma, Susumu; Kawamoto, Munetaka; Kiuchi, Takashi

2014-01-01

The W chromosome of the silkworm Bombyx mori has been known to determine femaleness for more than 80 years. However, the feminizing gene has not been molecularly identified, because the B. mori W chromosome is almost fully occupied by a large number of transposable elements. The W chromosome-derived feminizing factor of B. mori was recently shown to be a female-specific PIWI-interacting RNA (piRNA). piRNAs are small RNAs that potentially repress invading "non-self" elements (e.g., transposons and virus-like elements) by associating with PIWI proteins. Our results revealed that female-specific piRNA precursors, which we named Fem, are transcribed from the sex-determining region of the W chromosome at the early embryonic stage and are processed into a single mature piRNA (Fem piRNA). Fem piRNA forms a complex with Siwi (silkworm Piwi), which cleaves a protein-coding mRNA transcribed from the Z chromosome. RNA interference of this Z-linked gene, which we named Masc, revealed that this gene encodes a protein required for masculinization and dosage compensation. Fem and Masc both participate in the ping-pong cycle of the piRNA amplification loop by associating with the 2 B. mori PIWI proteins Siwi and BmAgo3 (silkworm Ago3), respectively, indicating that the piRNA-mediated interaction between the 2 sex chromosomes is the primary signal for the B. mori sex determination cascade. Fem is a non-transposable repetitive sequence on the W chromosome, whereas Masc is a single-copy protein-coding gene. It is of great interest how the piRNA system recognizes "self "Masc mRNA as "non-self" RNA.

Determination of the glass-transition temperature of proteins from a viscometric approach.

Science.gov (United States)

Monkos, Karol

2015-03-01

All fully hydrated proteins undergo a distinct change in their dynamical properties at glass-transition temperature Tg. To determine indirectly this temperature for dry albumins, the viscosity measurements of aqueous solutions of human, equine, ovine, porcine and rabbit serum albumin have been conducted at a wide range of concentrations and at temperatures ranging from 278 K to 318 K. Viscosity-temperature dependence of the solutions is discussed on the basis of the three parameters equation resulting from Avramov's model. One of the parameter in the Avramov's equation is the glass-transition temperature. For all studied albumins, Tg of a solution monotonically increases with increasing concentration. The glass-transition temperature of a solution depends both on Tg for a dissolved dry protein Tg,p and water Tg,w. To obtain Tg,p for each studied albumin the modified Gordon-Taylor equation was applied. This equation describes the dependence of Tg of a solution on concentration, and Tg,p and a parameter depending on the strength of the protein-solvent interaction are the fitting parameters. Thus determined the glass-transition temperature for the studied dry albumins is in the range (215.4-245.5)K. Copyright © 2014 Elsevier B.V. All rights reserved.

Temperature Dependence of Arn+ Cluster Backscattering from Polymer Surfaces: a New Method to Determine the Surface Glass Transition Temperature.

Science.gov (United States)

Poleunis, Claude; Cristaudo, Vanina; Delcorte, Arnaud

2018-01-01

In this work, time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to study the intensity variations of the backscattered Ar n + clusters as a function of temperature for several amorphous polymer surfaces (polyolefins, polystyrene, and polymethyl methacrylate). For all these investigated polymers, our results show a transition of the ratio Ar 2 + /(Ar 2 + + Ar 3 + ) when the temperature is scanned from -120 °C to +125 °C (the exact limits depend on the studied polymer). This transition generally spans over a few tens of degrees and the temperature of the inflection point of each curve is always lower than the bulk glass transition temperature (T g ) reported for the considered polymer. Due to the surface sensitivity of the cluster backscattering process (several nanometers), the presented analysis could provide a new method to specifically evaluate a surface transition temperature of polymers, with the same lateral resolution as the gas cluster beam. Graphical abstract ᅟ.

MPK-1 ERK controls membrane organization in C. elegans oogenesis via a sex-determination module.

Science.gov (United States)

Arur, Swathi; Ohmachi, Mitsue; Berkseth, Matt; Nayak, Sudhir; Hansen, David; Zarkower, David; Schedl, Tim

2011-05-17

Tissues that generate specialized cell types in a production line must coordinate developmental mechanisms with physiological demand, although how this occurs is largely unknown. In the Caenorhabditis elegans hermaphrodite, the developmental sex-determination cascade specifies gamete sex in the distal germline, while physiological sperm signaling activates MPK-1/ERK in the proximal germline to control plasma membrane biogenesis and organization during oogenesis. We discovered repeated utilization of a self-contained negative regulatory module, consisting of NOS-3 translational repressor, FEM-CUL-2 (E3 ubiquitin ligase), and TRA-1 (Gli transcriptional repressor), which acts both in sex determination and in physiological demand control of oogenesis, coordinating these processes. In the distal germline, where MPK-1 is not activated, TRA-1 represses the male fate as NOS-3 functions in translational repression leading to inactivation of the FEM-CUL-2 ubiquitin ligase. In the proximal germline, sperm-dependent physiological MPK-1 activation results in phosphorylation-based inactivation of NOS-3, FEM-CUL-2-mediated degradation of TRA-1 and the promotion of membrane organization during oogenesis. Copyright © 2011 Elsevier Inc. All rights reserved.

Discounting of money and sex: effects of commodity and temporal position in stimulant-dependent men and women.

Science.gov (United States)

Jarmolowicz, David P; Landes, Reid D; Christensen, Darren R; Jones, Bryan A; Jackson, Lisa; Yi, Richard; Bickel, Warren K

2014-11-01

Research on delay discounting has contributed to the understanding of numerous addiction-related phenomena. For example, studies have shown that substance dependent individuals discount their addictive substances (e.g., cocaine) more rapidly than they do other commodities (e.g., money). Recent research has shown that substance dependent individuals discount delayed sex more rapidly than delayed money, and their discounting rates for delayed sex were higher than those of non-addicted individuals. The particular reason that delay discounting rates for sex are higher than those for money, however, are unclear. Do individuals discount delayed sex rapidly because immediate sex is particularly appealing or because delayed sex does not retain its value? Moreover, do the same factors influence men and women's choices? The current study examined delay discounting in four conditions (money now versus money later; sex now versus sex later; money now, versus sex later; sex now versus money later) in cocaine dependent men and women. The procedures used isolated the role of the immediate versus delayed commodity. For men, the higher rates of delay discounting for sex were because delayed sex did not retain its value, whereas both the immediate and delayed commodity influenced the female participants' decisions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mutations in the testis-specific enhancer of SOX9 in the SRY independent sex-determining mechanism in the genus Tokudaia.

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Ryutaro Kimura

Full Text Available SRY (sex-determining region Y is widely conserved in eutherian mammals as a sex-determining gene located on the Y chromosome. SRY proteins bind to the testis-specific enhancer of SOX9 (TES with SF1 to upregulate SOX9 expression in undifferentiated gonads of XY embryos of humans and mice. The core region within TES, named TESCO, is an important enhancer for mammalian sex determination. We show that TESCO of the genus Tokudaia lost enhancer activity caused by mutations in its SRY and SF1 binding sites. Two species of Tokudaia do not have the Y chromosome or SRY, and one species has multiple SRYs located on the neo-Y chromosome consisting of the Y fused with an autosome. The sequence of Tokudaia TESCO exhibited more than 83% identity with mouse TESCO, however, nucleotide substitution(s were found in two out of three SRY binding sites and in five out of six SF1 binding sites. TESCO of all species showed low enhancer activity in cells co-transfected with SRY and SF1, and SOX9 and SF1 in reporter gene assays. Mutated TESCO, in which nucleotide substitutions found in SRY and SF1 binding sites were replaced with mouse sequence, recovered the activity. Furthermore, SRYs of the SRY-positive species could not activate the mutated TESCO or mouse TESCO, suggesting that SRYs lost function as a sex-determining gene any more. Our results indicate that the SRY dependent sex-determining mechanism was lost in a common ancestor of the genus Tokudaia caused by nucleotide substitutions in SRY and SF1 binding sites after emergence of a new sex-determining gene. We present the first evidence for an intermediate stage of the switchover from SRY to a new sex-determining gene in the evolution of mammalian sex-determining mechanism.

Mutations in the testis-specific enhancer of SOX9 in the SRY independent sex-determining mechanism in the genus Tokudaia.

Science.gov (United States)

Kimura, Ryutaro; Murata, Chie; Kuroki, Yoko; Kuroiwa, Asato

2014-01-01

SRY (sex-determining region Y) is widely conserved in eutherian mammals as a sex-determining gene located on the Y chromosome. SRY proteins bind to the testis-specific enhancer of SOX9 (TES) with SF1 to upregulate SOX9 expression in undifferentiated gonads of XY embryos of humans and mice. The core region within TES, named TESCO, is an important enhancer for mammalian sex determination. We show that TESCO of the genus Tokudaia lost enhancer activity caused by mutations in its SRY and SF1 binding sites. Two species of Tokudaia do not have the Y chromosome or SRY, and one species has multiple SRYs located on the neo-Y chromosome consisting of the Y fused with an autosome. The sequence of Tokudaia TESCO exhibited more than 83% identity with mouse TESCO, however, nucleotide substitution(s) were found in two out of three SRY binding sites and in five out of six SF1 binding sites. TESCO of all species showed low enhancer activity in cells co-transfected with SRY and SF1, and SOX9 and SF1 in reporter gene assays. Mutated TESCO, in which nucleotide substitutions found in SRY and SF1 binding sites were replaced with mouse sequence, recovered the activity. Furthermore, SRYs of the SRY-positive species could not activate the mutated TESCO or mouse TESCO, suggesting that SRYs lost function as a sex-determining gene any more. Our results indicate that the SRY dependent sex-determining mechanism was lost in a common ancestor of the genus Tokudaia caused by nucleotide substitutions in SRY and SF1 binding sites after emergence of a new sex-determining gene. We present the first evidence for an intermediate stage of the switchover from SRY to a new sex-determining gene in the evolution of mammalian sex-determining mechanism.

Pulp tissue in sex determination: A fluorescent microscopic study

Science.gov (United States)

Nayar, Amit; Singh, Harkanwal Preet; Leekha, Swati

2014-01-01

Aims: To determine and compare the reliability of pulp tissue in determination of sex and to analyze whether caries have any effect on fluorescent body test. Materials and Methods: This study was carried on 50 maxillary and mandibular teeth (25 male teeth and 25 female teeth), which were indicated for extraction. The teeth are categorized into 5 groups, 10 each (5 from males and 5 from females) on the basis of caries progression. The pulp cells are stained with quinacrine hydrochloride and observed with fluorescent microscope for fluorescent body. Gender is determined by identification of Y chromosome fluorescence in dental pulp. Results: Fluorescent bodies were found to be more in sound teeth in males as the caries increase the mean percentage of fluorescent bodies observed decreases in males. We also observed the fluorescent spots in females, and the value of the spot increases in female as the caries progresses, thereby giving false positive results in females. Conclusion: Sex determination by fluorescent staining of the Y chromosome is a reliable technique in teeth with healthy pulps or caries with enamel or up to half way of dentin. Teeth with caries involving pulp cannot be used for sex determination. PMID:25125912

The Temperature Condition of the Plate with Temperature-Dependent Thermal Conductivity and Energy Release

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V. S. Zarubin

2016-01-01

Full Text Available The temperature state of a solid body, in addition to the conditions of its heat exchange with the environment, can greatly depend on the heat release (or heat absorption processes within the body volume. Among the possible causes of these processes should be noted such as a power release in the fuel elements of nuclear reactors, exothermic or endothermic chemical reactions in the solid body material, which respectively involve heat release or absorbtion, heat transfer of a part of the electric power in the current-carrying conductors (so-called Joule’s heat or the energy radiation penetrating into the body of a semitransparent material, etc. The volume power release characterizes an intensity of these processes.The extensive list of references to the theory of heat conductivity of solids offers solutions to problems to determine a stationary (steady over time and non-stationary temperature state of the solids (as a rule, of the canonical form, which act as the sources of volume power release. Thus, in general case, a possibility for changing power release according to the body volume and in solving the nonstationary problems also a possible dependence of this value on the time are taken into consideration.However, in real conditions the volume power release often also depends on the local temperature, and such dependence can be nonlinear. For example, with chemical reactions the intensity of heat release or absorption is in proportion to their rate, which, in turn, is sensitive to the temperature value, and a dependence on the temperature is exponential. A further factor that in such cases makes the analysis of the solid temperature state complicated, is dependence on the temperature and the thermal conductivity of this body material, especially when temperature distribution therein  is significantly non-uniform. Taking into account the influence of these factors requires the mathematical modeling methods, which allow us to build an adequate

Mechanical properties and dependence with temperature of tetragonal polycrystalline zirconia materials

International Nuclear Information System (INIS)

Orange, G.

1986-01-01

Polycrystalline zirconia materials with a high content of metastable tetragonal phase have been obtained by pressureless sintering from experimental powders. Mechanical properties have been determined at room temperature and compared with similar materials. The fracture strength (σ /SUB f/ ) and fracture toughness (K /SUB 1c/ ) temperature dependence has been studied, in air environment up to 1000 0 C. Microstructure was studied by SEM examinations of fracture faces and TEM observations. Fracture toughness (of about 10 MPa √m at room temperature) decreases from 200 0 C to 800 0 C. The critical temperature (T /SUB c/ ) is estimated at 600 0 C. We observe an important decreases of fracture strength at 200 0 C. These mechanical properties are discussed on the basis of the stability of the tetragonal phase depending on additive content, grain size and temperature

An Immunohistochemical Approach to Identify the Sex of Young Marine Turtles.

Science.gov (United States)

Tezak, Boris M; Guthrie, Kathleen; Wyneken, Jeanette

2017-08-01

Marine turtles exhibit temperature-dependent sex determination (TSD). During critical periods of embryonic development, the nest's thermal environment directs whether an embryo will develop as a male or female. At warmer sand temperatures, nests tend to produce female-biased sex ratios. The rapid increase of global temperature highlights the need for a clear assessment of its effects on sea turtle sex ratios. However, estimating hatchling sex ratios at rookeries remains imprecise due to the lack of sexual dimorphism in young marine turtles. We rely mainly upon laparoscopic procedures to verify hatchling sex; however, in some species, morphological sex can be ambiguous even at the histological level. Recent studies using immunohistochemical (IHC) techniques identified that embryonic snapping turtle (Chelydra serpentina) ovaries overexpressed a particular cold-induced RNA-binding protein in comparison to testes. This feature allows the identification of females vs. males. We modified this technique to successfully identify the sexes of loggerhead sea turtle (Caretta caretta) hatchlings, and independently confirmed the results by standard histological and laparoscopic methods that reliably identify sex in this species. We next tested the CIRBP IHC method on gonad samples from leatherback turtles (Dermochelys coriacea). Leatherbacks display delayed gonad differentiation, when compared to other sea turtles, making hatchling gonads difficult to sex using standard H&E stain histology. The IHC approach was successful in both C. caretta and D. coriacea samples, offering a much-needed tool to establish baseline hatchling sex ratios, particularly for assessing impacts of climate change effects on leatherback turtle hatchlings and sea turtle demographics. Anat Rec, 300:1512-1518, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Suppressing gravitino thermal production with a temperature-dependent messenger coupling

International Nuclear Information System (INIS)

Badziak, Marcin; Dalianis, Ioannis; Lalak, Zygmunt

2016-01-01

We show that the constraints on GMSB theories from the gravitino cosmology can be significantly relaxed if the messenger-spurion coupling is temperature dependent. We demonstrate this novel mechanism in a scenario in which this coupling depends on the VEV of an extra singlet field S that interacts with the thermalized plasma which can result in a significantly suppressed gravitino production rate. In such a scenario the relic gravitino abundance is determined by the thermal dynamics of the S field and it is easy to fit the observed dark matter abundance evading the stringent constraints on the reheating temperature, thus making gravitino dark matter consistent with thermal leptogenesis.

Sexy splicing: regulatory interplays governing sex determination from Drosophila to mammals.

Science.gov (United States)

Lalli, Enzo; Ohe, Kenji; Latorre, Elisa; Bianchi, Marco E; Sassone-Corsi, Paolo

2003-02-01

A remarkable array of strategies is used to produce sexual differentiation in different species. Complex gene hierarchies govern sex determination pathways, as exemplified by the classic D. melanogaster paradigm, where an interplay of transcriptional, splicing and translational mechanisms operate. Molecular studies support the hypothesis that genetic sex determination pathways evolved in reverse order, from downstream to upstream genes, in the cascade. The recent identification of a role for the key regulatory factors SRY and WT1(+KTS) in pre-mRNA splicing indicates that important steps in the mammalian sex determination process are likely to operate at the post-transcriptional level.

Some progress in sexual reproduction and sex determination of ...

African Journals Online (AJOL)

As a result of this, elucidating the basic physiological mechanisms of algae becomes even more urgent. Of all the fields, sexual reproduction and sex determination are basic and essential aspects. In this review, we summarized the advances of sex in several typical algae which are of great economic importance and often ...

Sex determination: ways to evolve a hermaphrodite.

OpenAIRE

Braendle , Christian; Félix , Marie-Anne

2006-01-01

Most species of the nematode genus Caenorhabditis reproduce through males and females; C. elegans and C. briggsae, however, produce self-fertile hermaphrodites instead of females. These transitions to hermaphroditism evolved convergently through distinct modifications of germline sex determination mechanisms.

Time-, Sex-, and Dose-Dependent Alterations of the Gut Microbiota by Consumption of Dietary Daikenchuto (TU-100

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Jun Miyoshi

2018-01-01

Full Text Available Medications or dietary components can affect both the host and the host’s gut microbiota. Changes in the microbiota may influence medication efficacy and interactions. Daikenchuto (TU-100, a herbal medication, comprised of ginger, ginseng, and Japanese pepper, is widely used in Japanese traditional Kampo medicine for intestinal motility and postoperative paralytic ileus. We previously showed in mice that consumption of TU-100 for 4 weeks changed the gut microbiota and increased bioavailability of bacterial ginsenoside metabolites. Since TU-100 is prescribed in humans for months to years, we examined the time- and sex-dependent effects of TU-100 on mouse gut microbiota. Oral administration of 1.5% TU-100 for 24 weeks caused more pronounced changes in gut microbiota in female than in male mice. Changes in both sexes largely reverted to baseline upon TU-100 withdrawal. Effects were time and dose dependent. The microbial profiles reverted to baseline within 4 weeks after withdrawal of 0.75% TU-100 but were sustained after withdrawal of 3% TU-100. In summary, dietary TU-100 changed mouse microbiota in a time-, sex-, and dose-dependent manner. These findings may be taken into consideration when determining optimizing dose for conditions of human health and disease with the consideration of differences in composition and response of the human intestinal microbiota.

Temperature and composition dependence of birefringence of lithium-tantalate crystals determined by holographic scattering

International Nuclear Information System (INIS)

Bastwoeste, K.; Schwalenberg, S.; Baeumer, Ch.; Kraetzig, E.

2003-01-01

Iron-doped lithium-tantalate samples with different compositions ranging from the congruently melting to the stoichiometric one are analyzed by anisotropic holographic scattering. The temperature dependence of the birefringence yields information on the composition of the crystals. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Temperature and composition dependence of birefringence of lithium-tantalate crystals determined by holographic scattering

Energy Technology Data Exchange (ETDEWEB)

Bastwoeste, K.; Schwalenberg, S.; Baeumer, Ch.; Kraetzig, E. [Fachbereich Physik, Universitaet Osnabrueck, D-49069 Osnabrueck (Germany)

2003-09-01

Iron-doped lithium-tantalate samples with different compositions ranging from the congruently melting to the stoichiometric one are analyzed by anisotropic holographic scattering. The temperature dependence of the birefringence yields information on the composition of the crystals. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

MORPHOMETRIC EVALUATION OF FORAMEN MAGNUM FOR SEX DETERMINATION IN A DOCUMENTED NORTH INDIAN SAMPLE

OpenAIRE

Jain; Alok Kumar; Pankaj

2013-01-01

ABSTRACT: Sex determination is used in anthropology, forensic medicine and medic o - legal cases. It is (1) remarked that “next to the pelvis, the skull is the most easily sexed portion of the skeleton”. It has been suggested (2 - 5) that the measurements of the foramen magnum are useful for determining the sex. There are two osteological techniques used to determine the sex of an individual; the first is visual assessment to evaluate the morphological sex tra...

Absence of complementary sex determination in the parasitoid wasp genus Asobara (Hymenoptera: Braconidae.

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Wen-Juan Ma

Full Text Available An attractive way to improve our understanding of sex determination evolution is to study the underlying mechanisms in closely related species and in a phylogenetic perspective. Hymenopterans are well suited owing to the diverse sex determination mechanisms, including different types of Complementary Sex Determination (CSD and maternal control sex determination. We investigated different types of CSD in four species within the braconid wasp genus Asobara that exhibit diverse life-history traits. Nine to thirteen generations of inbreeding were monitored for diploid male production, brood size, offspring sex ratio, and pupal mortality as indicators for CSD. In addition, simulation models were developed to compare these observations to predicted patterns for multilocus CSD with up to ten loci. The inbreeding regime did not result in diploid male production, decreased brood sizes, substantially increased offspring sex ratios nor in increased pupal mortality. The simulations further allowed us to reject CSD with up to ten loci, which is a strong refutation of the multilocus CSD model. We discuss how the absence of CSD can be reconciled with the variation in life-history traits among Asobara species, and the ramifications for the phylogenetic distribution of sex determination mechanisms in the Hymenoptera.

Efficacy of cheiloscopy in determination of sex among South indians.

Science.gov (United States)

Kautilya D, Vijay; Bodkha, Pravir; Rajamohan, Naveen

2013-10-01

Human identification plays a vital role in any crime investigation. Along with the various other established methods, cheiloscopy also plays a key role in linking the criminal with the crime. The ability of a technique in differentiating the sex of a person in the field can help in screening a large number of suspects. This study evaluated the efficacy of cheiloscopy in determination of sex among South Indians. It also studied the pattern of dimorphism in the lips and lip prints of south Indians. Lip prints from 100 medical students (50 males and 50 females) were obtained and were analyzed, based on Tsuchihashi and Suzuki classification, to check for dimorphism. Lip dimensions were studied by using standard sliding calipers for dimorphism. The most common pattern of lip print among males was Type III as compared to Type I in females. The outer four portions of the lip showed statistically significant differences in males and females. Middle portion of the lip was statistically insignificant in sex determination, based on lip print patterns. Thickness of the lip was significantly larger in males as compared to that in females and this criterion could be used to establish a logistic regression for determination of sex of a person. Lips not only significantly differ among the males and females in the pattern of the lip print that they present, but they also differ in their size. These features can effectively be used to determine the sex of a person accurately.

A single sex pheromone receptor determines chemical response specificity of sexual behavior in the silkmoth Bombyx mori.

Science.gov (United States)

Sakurai, Takeshi; Mitsuno, Hidefumi; Haupt, Stephan Shuichi; Uchino, Keiro; Yokohari, Fumio; Nishioka, Takaaki; Kobayashi, Isao; Sezutsu, Hideki; Tamura, Toshiki; Kanzaki, Ryohei

2011-06-01

In insects and other animals, intraspecific communication between individuals of the opposite sex is mediated in part by chemical signals called sex pheromones. In most moth species, male moths rely heavily on species-specific sex pheromones emitted by female moths to identify and orient towards an appropriate mating partner among a large number of sympatric insect species. The silkmoth, Bombyx mori, utilizes the simplest possible pheromone system, in which a single pheromone component, (E, Z)-10,12-hexadecadienol (bombykol), is sufficient to elicit full sexual behavior. We have previously shown that the sex pheromone receptor BmOR1 mediates specific detection of bombykol in the antennae of male silkmoths. However, it is unclear whether the sex pheromone receptor is the minimally sufficient determination factor that triggers initiation of orientation behavior towards a potential mate. Using transgenic silkmoths expressing the sex pheromone receptor PxOR1 of the diamondback moth Plutella xylostella in BmOR1-expressing neurons, we show that the selectivity of the sex pheromone receptor determines the chemical response specificity of sexual behavior in the silkmoth. Bombykol receptor neurons expressing PxOR1 responded to its specific ligand, (Z)-11-hexadecenal (Z11-16:Ald), in a dose-dependent manner. Male moths expressing PxOR1 exhibited typical pheromone orientation behavior and copulation attempts in response to Z11-16:Ald and to females of P. xylostella. Transformation of the bombykol receptor neurons had no effect on their projections in the antennal lobe. These results indicate that activation of bombykol receptor neurons alone is sufficient to trigger full sexual behavior. Thus, a single gene defines behavioral selectivity in sex pheromone communication in the silkmoth. Our findings show that a single molecular determinant can not only function as a modulator of behavior but also as an all-or-nothing initiator of a complex species-specific behavioral sequence.

A single sex pheromone receptor determines chemical response specificity of sexual behavior in the silkmoth Bombyx mori.

Directory of Open Access Journals (Sweden)

Takeshi Sakurai

2011-06-01

Full Text Available In insects and other animals, intraspecific communication between individuals of the opposite sex is mediated in part by chemical signals called sex pheromones. In most moth species, male moths rely heavily on species-specific sex pheromones emitted by female moths to identify and orient towards an appropriate mating partner among a large number of sympatric insect species. The silkmoth, Bombyx mori, utilizes the simplest possible pheromone system, in which a single pheromone component, (E, Z-10,12-hexadecadienol (bombykol, is sufficient to elicit full sexual behavior. We have previously shown that the sex pheromone receptor BmOR1 mediates specific detection of bombykol in the antennae of male silkmoths. However, it is unclear whether the sex pheromone receptor is the minimally sufficient determination factor that triggers initiation of orientation behavior towards a potential mate. Using transgenic silkmoths expressing the sex pheromone receptor PxOR1 of the diamondback moth Plutella xylostella in BmOR1-expressing neurons, we show that the selectivity of the sex pheromone receptor determines the chemical response specificity of sexual behavior in the silkmoth. Bombykol receptor neurons expressing PxOR1 responded to its specific ligand, (Z-11-hexadecenal (Z11-16:Ald, in a dose-dependent manner. Male moths expressing PxOR1 exhibited typical pheromone orientation behavior and copulation attempts in response to Z11-16:Ald and to females of P. xylostella. Transformation of the bombykol receptor neurons had no effect on their projections in the antennal lobe. These results indicate that activation of bombykol receptor neurons alone is sufficient to trigger full sexual behavior. Thus, a single gene defines behavioral selectivity in sex pheromone communication in the silkmoth. Our findings show that a single molecular determinant can not only function as a modulator of behavior but also as an all-or-nothing initiator of a complex species

Direct LAMP Assay without Prior DNA Purification for Sex Determination of Papaya

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Chi-Chu Tsai

2016-09-01

Full Text Available Papaya (Carica papaya L. is an economically important tropical fruit tree with hermaphrodite, male and female sex types. Hermaphroditic plants are the major type used for papaya production because their fruits have more commercial advantages than those of female plants. Sex determination of the seedlings, or during the early growth stages, is very important for the papaya seedling industry. Thus far, the only method for determining the sex type of a papaya at the seedling stage has been DNA analysis. In this study, a molecular technique—based on DNA analysis—was developed for detecting male-hermaphrodite-specific markers to examine the papaya’s sex type. This method is based on the loop-mediated isothermal amplification (LAMP and does not require prior DNA purification. The results show that the method is an easy, efficient, and inexpensive way to determine a papaya’s sex. This is the first report on the LAMP assay, using intact plant materials-without DNA purification-as samples for the analysis of sex determination of papaya. We found that using high-efficiency DNA polymerase was essential for successful DNA amplification, using trace intact plant material as a template DNA source.

Temperature dependence of 1H NMR chemical shifts and its influence on estimated metabolite concentrations.

Science.gov (United States)

Wermter, Felizitas C; Mitschke, Nico; Bock, Christian; Dreher, Wolfgang

2017-12-01

Temperature dependent chemical shifts of important brain metabolites measured by localised 1 H MRS were investigated to test how the use of incorrect prior knowledge on chemical shifts impairs the quantification of metabolite concentrations. Phantom measurements on solutions containing 11 metabolites were performed on a 7 T scanner between 1 and 43 °C. The temperature dependence of the chemical shift differences was fitted by a linear model. Spectra were simulated for different temperatures and analysed by the AQSES program (jMRUI 5.2) using model functions with chemical shift values for 37 °C. Large differences in the temperature dependence of the chemical shift differences were determined with a maximum slope of about ±7.5 × 10 -4  ppm/K. For 32-40 °C, only minor quantification errors resulted from using incorrect chemical shifts, with the exception of Cr and PCr. For 1-10 °C considerable quantification errors occurred if the temperature dependence of the chemical shifts was neglected. If 1 H MRS measurements are not performed at 37 °C, for which the published chemical shift values have been determined, the temperature dependence of chemical shifts should be considered to avoid systematic quantification errors, particularly for measurements on animal models at lower temperatures.

Assessing the Temperature Dependence of Narrow-Band Raman Water Vapor Lidar Measurements: A Practical Approach

Science.gov (United States)

Whiteman, David N.; Venable, Demetrius D.; Walker, Monique; Cardirola, Martin; Sakai, Tetsu; Veselovskii, Igor

2013-01-01

Narrow-band detection of the Raman water vapor spectrum using the lidar technique introduces a concern over the temperature dependence of the Raman spectrum. Various groups have addressed this issue either by trying to minimize the temperature dependence to the point where it can be ignored or by correcting for whatever degree of temperature dependence exists. The traditional technique for performing either of these entails accurately measuring both the laser output wavelength and the water vapor spectral passband with combined uncertainty of approximately 0.01 nm. However, uncertainty in interference filter center wavelengths and laser output wavelengths can be this large or larger. These combined uncertainties translate into uncertainties in the magnitude of the temperature dependence of the Raman lidar water vapor measurement of 3% or more. We present here an alternate approach for accurately determining the temperature dependence of the Raman lidar water vapor measurement. This alternate approach entails acquiring sequential atmospheric profiles using the lidar while scanning the channel passband across portions of the Raman water vapor Q-branch. This scanning is accomplished either by tilt-tuning an interference filter or by scanning the output of a spectrometer. Through this process a peak in the transmitted intensity can be discerned in a manner that defines the spectral location of the channel passband with respect to the laser output wavelength to much higher accuracy than that achieved with standard laboratory techniques. Given the peak of the water vapor signal intensity curve, determined using the techniques described here, and an approximate knowledge of atmospheric temperature, the temperature dependence of a given Raman lidar profile can be determined with accuracy of 0.5% or better. A Mathematica notebook that demonstrates the calculations used here is available from the lead author.

Molecular Sex Determination of Captive Komodo Dragons (Varanus komodoensis at Gembira Loka Zoo, Surabaya Zoo, and Ragunan Zoo, Indonesia

Directory of Open Access Journals (Sweden)

SRI SULANDARI

2014-06-01

Full Text Available Captive breeding of endangered species is often difficult, and may be hampered by many factors. Sexual monomorphism, in which males and females are not easily distinguishable, is one such factor and is a common problem in captive breeding of many avian and reptile species. Species-specific nuclear DNA markers, recently developed to identify portions of sex chromosomes, were employed in this study for sex determination of Komodo dragons (Varanus Komodoensis. Each animal was uniquely tagged using a passive integrated micro-transponder (TROVAN 100A type transponders of 13 mm in length and 2 mm in diameter. The sex of a total of 81 individual Komodo dragons (44 samples from Ragunan zoo, 26 samples from Surabaya zoo, and 11 samples from Gembira Loka zoo were determined using primers Ksex 1for and Ksex 3rev. A series of preliminary PCR amplifications were conducted using DNA from individuals of known sex. During these preliminary tests, researchers varied the annealing temperatures, number of cycles, and concentrations of reagents, in order to identify the best protocol for sex determination using our sample set. We thus developed our own PCR protocol for this study, which resulted in the amplification of band A in females and band C in males. Results from band B, however, turned out to be non-determinative in our study because, for females, band B was not always visible, and for males sometimes a similar, but lighter band was also amplified, making interpretation difficult. In this study, sex determination was based mainly on the difference in size between the female-specific 812 bp fragment and the homologous, longer fragment amplified for males.

Effect of nitrogen concentration on temperature dependent mechanical properties of vanadium

International Nuclear Information System (INIS)

Carlson, O.N.; Rehbein, D.K.

1979-01-01

The critical resolved shear stress and strain rate sensitivity of vanadium were determined for vanadium-nitrogen alloys over the temperature range of 77K to 400K for concentrations of 1 to 500 wt ppm nitrogen. The concentration dependence of the hardening rate agrees quite well with either the Fleischer or Labusch strengthening model but the combined temperature and concentration dependence follows more closely the form predicted by Ono and Sommer. The strain rate sensitivity exhibits a peak at 140K which decreases with increasing nitrogen content but above 250K there is a reversal in this effect. (orig.) [de

Determination of the mobility ratio in InSb at the temperature of the conductivity type conversion

Energy Technology Data Exchange (ETDEWEB)

Somogyi, K. [Research Institute for Technical Physics and Materials Science, HAS, 1525 Budapest, P.O. Box 49 (Hungary)

2005-05-01

The temperature dependence of magneto-transport in bulk p-type InSb was investigated, and a special approach was applied for the precise determination of the temperature dependence. Such measurements also allow the determination of the mobility ratio (b) which is known to be large in InSb. Although this type of investigation is standard, in this work an improved method of carrying out temperature-dependent Hall measurements is reported and improved calculations for the determination of large b values in InSb are presented. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Sex determination in Madagascar geckos of the genus Paroedura (Squamata: Gekkonidae): are differentiated sex chromosomes indeed so evolutionary stable?

Science.gov (United States)

Koubová, Martina; Johnson Pokorná, Martina; Rovatsos, Michail; Farkačová, Klára; Altmanová, Marie; Kratochvíl, Lukáš

2014-12-01

Among amniote vertebrates, geckos represent a clade with exceptional variability in sex determination; however, only a minority of species of this highly diverse group has been studied in this respect. Here, we describe for the first time a female heterogamety in the genus Paroedura, the group radiated in Madagascar and adjacent islands. We identified homomorphic ZZ/ZW sex chromosomes with a highly heterochromatic W chromosome in Paroedura masobe, Paroedura oviceps, Paroedura karstophila, Paroedura stumpffi, and Paroedura lohatsara. Comparative genomic hybridization (CGH) revealed that female-specific sequences are greatly amplified in the W chromosome of P. lohatsara and that P. gracilis seems to possess a derived system of multiple sex chromosomes. Contrastingly, neither CGH nor heterochromatin visualization revealed differentiated sex chromosomes in the members of the Paroedura picta-Paroedura bastardi-Paroedura ibityensis clade, which is phylogenetically nested within lineages with a heterochromatic W chromosome. As a sex ratio consistent with genotypic sex determination has been reported in P. picta, it appears that the members of the P. picta-P. bastardi-P. ibityensis clade possess homomorphic, poorly differentiated sex chromosomes and may represent a rare example of evolutionary loss of highly differentiated sex chromosomes. Fluorescent in situ hybridization (FISH) with a telomeric probe revealed a telomere-typical pattern in all species and an accumulation of telomeric sequences in the centromeric region of autosomes in P. stumpffi and P. bastardi. Our study adds important information for the greater understanding of the variability and evolution of sex determination in geckos and demonstrates how the geckos of the genus Paroedura provide an interesting model for studying the evolution of the sex chromosomes.

A simple equation for describing the temperature dependent growth of free-floating macrophytes

NARCIS (Netherlands)

Heide, van Tj.; Roijackers, R.M.M.; Nes, van E.H.; Peeters, E.T.H.M.

2006-01-01

Temperature is one of the most important factors determining growth rates of free-floating macrophytes in the field. To analyse and predict temperature dependent growth rates of these pleustophytes, modelling may play an important role. Several equations have been published for describing

Crossing regimes of temperature dependence in animal movement.

Science.gov (United States)

Gibert, Jean P; Chelini, Marie-Claire; Rosenthal, Malcolm F; DeLong, John P

2016-05-01

A pressing challenge in ecology is to understand the effects of changing global temperatures on food web structure and dynamics. The stability of these complex ecological networks largely depends on how predator-prey interactions may respond to temperature changes. Because predators and prey rely on their velocities to catch food or avoid being eaten, understanding how temperatures may affect animal movement is central to this quest. Despite our efforts, we still lack a mechanistic understanding of how the effect of temperature on metabolic processes scales up to animal movement and beyond. Here, we merge a biomechanical approach, the Metabolic Theory of Ecology and empirical data to show that animal movement displays multiple regimes of temperature dependence. We also show that crossing these regimes has important consequences for population dynamics and stability, which depend on the parameters controlling predator-prey interactions. We argue that this dependence upon interaction parameters may help explain why experimental work on the temperature dependence of interaction strengths has so far yielded conflicting results. More importantly, these changes in the temperature dependence of animal movement can have consequences that go well beyond ecological interactions and affect, for example, animal communication, mating, sensory detection, and any behavioral modality dependent on the movement of limbs. Finally, by not taking into account the changes in temperature dependence reported here we might not be able to properly forecast the impact of global warming on ecological processes and propose appropriate mitigation action when needed. © 2016 John Wiley & Sons Ltd.

High temperature increases the masculinization rate of the all-female (XX) rainbow trout "Mal" population.

Science.gov (United States)

Valdivia, Karina; Jouanno, Elodie; Volff, Jean-Nicolas; Galiana-Arnoux, Delphine; Guyomard, René; Helary, Louise; Mourot, Brigitte; Fostier, Alexis; Quillet, Edwige; Guiguen, Yann

2014-01-01

Salmonids are generally considered to have a robust genetic sex determination system with a simple male heterogamety (XX/XY). However, spontaneous masculinization of XX females has been found in a rainbow trout population of gynogenetic doubled haploid individuals. The analysis of this masculinization phenotype transmission supported the hypothesis of the involvement of a recessive mutation (termed mal). As temperature effect on sex differentiation has been reported in some salmonid species, in this study we investigated in detail the potential implication of temperature on masculinization in this XX mal-carrying population. Seven families issued from XX mal-carrying parents were exposed from the time of hatching to different rearing water temperatures ((8, 12 and 18°C), and the resulting sex-ratios were confirmed by histological analysis of both gonads. Our results demonstrate that masculinization rates are strongly increased (up to nearly two fold) at the highest temperature treatment (18°C). Interestingly, we also found clear differences between temperatures on the masculinization of the left versus the right gonads with the right gonad consistently more often masculinized than the left one at lower temperatures (8 and 12°C). However, the masculinization rate is also strongly dependent on the genetic background of the XX mal-carrying families. Thus, masculinization in XX mal-carrying rainbow trout is potentially triggered by an interaction between the temperature treatment and a complex genetic background potentially involving some part of the genetic sex differentiation regulatory cascade along with some minor sex-influencing loci. These results indicate that despite its rather strict genetic sex determinism system, rainbow trout sex differentiation can be modulated by temperature, as described in many other fish species.

A complex interaction of imprinted and maternal-effect genes modifies sex determination in Odd Sex (Ods) mice.

Science.gov (United States)

Poirier, Christophe; Qin, Yangjun; Adams, Carolyn P; Anaya, Yanett; Singer, Jonathan B; Hill, Annie E; Lander, Eric S; Nadeau, Joseph H; Bishop, Colin E

2004-11-01

The transgenic insertional mouse mutation Odd Sex (Ods) represents a model for the long-range regulation of Sox9. The mutation causes complete female-to-male sex reversal by inducing a male-specific expression pattern of Sox9 in XX Ods/+ embryonic gonads. We previously described an A/J strain-specific suppressor of Ods termed Odsm1(A). Here we show that phenotypic sex depends on a complex interaction between the suppressor and the transgene. Suppression can be achieved only if the transgene is transmitted paternally. In addition, the suppressor itself exhibits a maternal effect, suggesting that it may act on chromatin in the early embryo.

Condition dependence and the nature of genetic variation for male sex comb bristle number in Drosophila melanogaster.

Science.gov (United States)

Ahuja, Abha; De Vito, Scott; Singh, Rama S

2011-04-01

Genetic architecture of variation underlying male sex comb bristle number, a rapidly evolving secondary sexual character of Drosophila, was examined. First, in order to test for condition dependence, diet was manipulated in a set of ten Drosophila melanogaster full-sib families. We confirmed heightened condition dependent expression of sex comb bristle number and its female homologue (distal transverse row bristles) as compared to non-sex sternopleural bristles. Significant genotype by environment effects were detected for the sex traits indicating a genetic basis for condition dependence. Next we measured sex comb bristle number and sternopleural bristle number, as well as residual mass, a commonly used condition index, in a set of thirty half-sib families. Sire effect was not significant for sex comb and sternopleural bristle number, and we detected a strong dominance and/or maternal effect or X chromosome effect for both traits. A strong sire effect was detected for condition and its heritability was the highest as compared to sex comb and sternopleural bristles. We discuss our results in light of the rapid response to divergent artificial selection for sex comb bristle number reported previously. The nature of genetic variation for male sex traits continues to be an important unresolved issue in evolutionary biology.

Temperature dependence of LRE-HRE-TM thin films

Science.gov (United States)

Li, Zuoyi; Cheng, Xiaomin; Lin, Gengqi; Li, Zhen; Huang, Zhixin; Jin, Fang; Wang, Xianran; Yang, Xiaofei

2003-04-01

Temperature dependence of the properties of RE-TM thin films is very important for MO recording. In this paper, we studied the temperature dependence of the magnetic and magneto-optical properties of the amorphous LRE-HRE-TM single layer thin films and LRE-HRE-TM/HRE-TM couple-bilayered thin films. For LRE-HRE-TM single layer thin films, the temperature dependence of the magnetization was investigated by using the mean field theory. The experimental and theoretical results matched very well. With the LRE substitution in HRE-TM thin film, the compensation temperature Tcomp decreased and the curie temperature Tc remained unchanged. Kerr rotation angle became larger and the saturation magnetization Ms at room temperature increased. For LRE-HRE-TM/HRE-TM couple-bilayered thin films, comparisons of the temperature dependences of the coercivities and Kerr rotation angles were made between isolated sublayers and couple-bilayered thin film.

Transport characteristics of n-ZnO/p-Si heterojunction as determined from temperature dependent current–voltage measurements

Energy Technology Data Exchange (ETDEWEB)

Djiokap, S.R. Tankio, E-mail: stive.tankiodjiokap@nmmu.ac.za; Urgessa, Z.N.; Mbulanga, C.M.; Venter, A.; Botha, J.R.

2016-01-01

Zinc oxide (ZnO) nanorods have been synthesized by a two-step chemical bath deposition process on silicon substrates having different dopant densities and orientations. Scanning electron microscopy and X-ray diffraction analysis reveal that the orientation of the Si substrate does not affect the orientation, distribution or crystallinity of the nanostructures. The electrical properties of the ZnO/Si heterojunction are also investigated by current–voltage (I–V) measurements. The ideality factor is found to be 2.6 at 295 K, indicating that complex current transport mechanisms are at play. Temperature dependent I–V characteristics have been used to determine the dominant transport mechanism. The experimental results suggest that in the low bias region the current is dominated by a trap assisted multi-step tunneling process.

Effect of Temperature on Reproduction and Sex Ratio of Guppy (Poecilia reticulata Peters

Directory of Open Access Journals (Sweden)

H. Arfah

2007-01-01

Full Text Available Water temperature could affect the reproduction of broodstock and sex ratio of progeny.  In this study, broodstock of guppy (Poecilia reticulata Peters was reared in different temperature to determine its effect on reproduction of broodstock and sex ratio of their progeny. The result of study show that broodstock reared at 27°C produced more fry (16 males mean than that of 30°C (10 males, while broodstock reared at 33°C produced no progeny.  Percentage of male fish produced by broodstock reared at 30°C is higher than that of 27°C.  Incubation time of embryo before birth is sorter in broodstock reared at 30°C (4-12 days compared with 27°C (18-22 days.  However, several progeny of broodstock reared at 30°C had abnormal vertebrae. Keywords: guppy, Poecilia reticulata, sex reversal, reproduction, monosex   ABSTRAK Suhu air inkubasi diduga dapat mempengaruhi reproduksi induk ikan dan nisbah kelamin keturunannya.  Pada penelitian ini, induk ikan gapi (Poecilia reticulata Peters dipelihara pada suhu 27°C, 30°C dan suhu 33°C untuk mengetahui pengaruhnya terhadap reproduksi dan rasio kelamin keturunannya.  Hasil penelitian menunjukkan bahwa induk ikan gapi yang dipelihara pada suhu 27°C menghasilkan anak lebih banyak (rata-rata 16 ekor daripada di suhu 30°C (10 ekor, sementara induk gagal melahirkan pada suhu pemeliharaan 33°C. Proporsi anak jantan yang dihasilkan oleh induk yang dipelihara pada suhu 30°C lebih banyak dibandingkan pada suhu 27°C.  Waktu inkubasi embrio sebelum dilahirkan oleh induk yang dipelihara pada suhu 30°C lebih singkat, yaitu 4-12 hari, dibandingkan pada  suhu 27°C, 18-22 hari.  Namun demikian beberapa anak ikan yang lahir dari induk yang dipelihara pada suhu suhu 30°C mengalami abnormalitas pada bagian tulang belakangnya.  Kata kunci: ikan gapi, Poecilia reticulata, sex reversal, reproduksi, monoseks

Operating Cell Temperature Determination in Flat-Plate Photovoltaic Modules

International Nuclear Information System (INIS)

Chenlo, F.

2002-01-01

Two procedures (simplified and complete) to determine me operating cell temperature in photovoltaic modules operating in real conditions assuming isothermal stationary modules are presented in this work. Some examples are included that show me dependence of this temperature on several environmental (sky, ground and ambient temperatures, solar irradiance, wind speed, etc.) and structural (module geometry and size, encapsulating materials, anti reflexive optical coatings, etc.) factors and also on electrical module performance. In a further step temperature profiles for non-isothermal modules are analysed besides transitory effects due to variable irradiance and wind gusts. (Author) 27 refs

Temperature Dependence of Factors Controlling Isoprene Emissions

Science.gov (United States)

Duncan, Bryan N.; Yoshida, Yasuko; Damon, Megan R.; Douglass, Anne R.; Witte, Jacquelyn C.

2009-01-01

We investigated the relationship of variability in the formaldehyde (HCHO) columns measured by the Aura Ozone Monitoring Instrument (OMI) to isoprene emissions in the southeastern United States for 2005-2007. The data show that the inferred, regional-average isoprene emissions varied by about 22% during summer and are well correlated with temperature, which is known to influence emissions. Part of the correlation with temperature is likely associated with other causal factors that are temperature-dependent. We show that the variations in HCHO are convolved with the temperature dependence of surface ozone, which influences isoprene emissions, and the dependence of the HCHO column to mixed layer height as OMI's sensitivity to HCHO increases with altitude. Furthermore, we show that while there is an association of drought with the variation in HCHO, drought in the southeastern U.S. is convolved with temperature.

Temperature dependence of radiation chemistry of polymers

International Nuclear Information System (INIS)

Garrett, R.W.; Hill, D.J.T.; Le, T.T.; Milne, K.A.; O'Donnell, J.H.; Perera, S.M.C.; Pomery, P.J.

1990-01-01

Chemical reactions which occur during radiolysis of polymers usually show an increase in rate with increasing temperature that can be described by an Arrhenius relationship. The magnitude of the activation energy can vary widely and is affected by physical, as well as chemical, factors. Different reaction rates may be expected in crystalline and amorphous morphologies, and in glassy and rubbery regions. The temperature dependence of radiolysis reactions can be expected to show discontinuities at the glass and melting transitions, T g and T m . The ceiling temperature, T c , for polymerization/depolymerization will also affect the rate of degradation, especially for depropagation to monomer. The temperature for this effect depends on the molecular structure of the polymer. The temperature dependence of free radical reactions can be studied by cryogenic trapping and ESR spectroscopy during thermal profiling. Increased degradation rates at high dose rates can be due to increased temperatures resulting from energy absorption

First Assessment of the Sex Ratio for an East Pacific Green Sea Turtle Foraging Aggregation: Validation and Application of a Testosterone ELISA.

Directory of Open Access Journals (Sweden)

Camryn D Allen

Full Text Available Determining sex ratios of endangered populations is important for wildlife management, particularly species subject to sex-specific threats or that exhibit temperature-dependent sex determination. Sea turtle sex is determined by incubation temperature and individuals lack external sex-based traits until sexual maturity. Previous research utilized serum/plasma testosterone radioimmunoassays (RIA to determine sex in immature/juvenile sea turtles. However, there has been a growing application of enzyme-linked immunosorbent assay (ELISA for wildlife endocrinology studies, but no study on sea turtles has compared the results of ELISA and RIA. This study provides the first sex ratio for a threatened East Pacific green sea turtle (Chelonia mydas foraging aggregation, a critical step for future management of this species. Here, we validate a testosterone ELISA and compare results between RIA and ELISA of duplicate samples. The ELISA demonstrated excellent correspondence with the RIA for providing testosterone concentrations for sex determination. Neither assay proved reliable for predicting the sex of reproductively active females with increased testosterone production. We then applied ELISA to examine the sex ratio of 69 green turtles foraging in San Diego Bay, California. Of 45 immature turtles sampled, sex could not be determined for three turtles because testosterone concentrations fell between the ranges for either sex (females: 4.1-113.1 pg/mL, males: 198.4-2,613.0 pg/mL and these turtles were not subsequently recaptured to enable sex determination; using a Bayesian model to predict probabilities of turtle sex we predicted all three 'unknowns' were female (> 0.86. Additionally, the model assigned all turtles with their correct sex (if determined at recapture with 100% accuracy. Results indicated a female bias (2.83F:1M among all turtles in the aggregation; when focusing only on putative immature turtles the sex ratio was 3.5F:1M. With appropriate

Sex-dependent alteration of cardiac cytochrome P450 gene expression by doxorubicin in C57Bl/6 mice.

Science.gov (United States)

Grant, Marianne K O; Seelig, Davis M; Sharkey, Leslie C; Zordoky, Beshay N

2017-01-01

There is inconclusive evidence about the role of sex as a risk factor for doxorubicin (DOX)-induced cardiotoxicity. Recent experimental studies have shown that adult female rats are protected against DOX-induced cardiotoxicity. However, the mechanisms of this sexual dimorphism are not fully elucidated. We have previously demonstrated that DOX alters the expression of several cytochrome P450 (CYP) enzymes in the hearts of male rats. Nevertheless, the sex-dependent effect of DOX on the expression of CYP enzymes is still not known. Therefore, in the present study, we determined the effect of acute DOX exposure on the expression of CYP genes in the hearts of both male and female C57Bl/6 mice. Acute DOX cardiotoxicity was induced by a single intraperitoneal injection of 20 mg/kg DOX in male and female adult C57Bl/6 mice. Cardiac function was assessed 5 days after DOX exposure by trans-thoracic echocardiography. Mice were euthanized 1 day or 6 days after DOX or saline injection. Thereafter, the hearts were harvested and weighed. Heart sections were evaluated for pathological lesions. Total RNA was extracted and expression of natriuretic peptides, inflammatory and apoptotic markers, and CYP genes was measured by real-time PCR. Adult female C57Bl/6 mice were protected from acute DOX-induced cardiotoxicity as they show milder pathological lesions, less inflammation, and faster recovery from DOX-induced apoptosis and DOX-mediated inhibition of beta-type natriuretic peptide. Acute DOX exposure altered the gene expression of multiple CYP genes in a sex-dependent manner. In 24 h, DOX exposure caused male-specific induction of Cyp1b1 and female-specific induction of Cyp2c29 and Cyp2e1. Acute DOX exposure causes sex-dependent alteration of cardiac CYP gene expression. Since cardiac CYP enzymes metabolize several endogenous compounds to biologically active metabolites, sex-dependent alteration of CYP genes may play a role in the sexual dimorphism of acute DOX

Sex determination strategies in 2012: towards a common regulatory model?

Science.gov (United States)

2012-01-01

Sex determination is a complicated process involving large-scale modifications in gene expression affecting virtually every tissue in the body. Although the evolutionary origin of sex remains controversial, there is little doubt that it has developed as a process of optimizing metabolic control, as well as developmental and reproductive functions within a given setting of limited resources and environmental pressure. Evidence from various model organisms supports the view that sex determination may occur as a result of direct environmental induction or genetic regulation. The first process has been well documented in reptiles and fish, while the second is the classic case for avian species and mammals. Both of the latter have developed a variety of sex-specific/sex-related genes, which ultimately form a complete chromosome pair (sex chromosomes/gonosomes). Interestingly, combinations of environmental and genetic mechanisms have been described among different classes of animals, thus rendering the possibility of a unidirectional continuous evolutionary process from the one type of mechanism to the other unlikely. On the other hand, common elements appear throughout the animal kingdom, with regard to a) conserved key genes and b) a central role of sex steroid control as a prerequisite for ultimately normal sex differentiation. Studies in invertebrates also indicate a role of epigenetic chromatin modification, particularly with regard to alternative splicing options. This review summarizes current evidence from research in this hot field and signifies the need for further study of both normal hormonal regulators of sexual phenotype and patterns of environmental disruption. PMID:22357269

Understanding Biological Rates and their Temperature Dependence, from Enzymes to Ecosystems

Science.gov (United States)

Prentice, E.; Arcus, V. L.

2017-12-01

Temperature responses over various scales in biological systems follow a similar pattern; negative curvature results in an optimum temperature (Topt) for activity/growth/turnover, with decreases in rates on either side of Topt. Previously this downturn in rates at high temperatures has been attributed to enzyme denaturation, where a failing of the basic driving units of metabolism was used to describe curvature at the enzyme and organism level. However, recent developments in our understanding of the factors governing enzyme rates at different temperatures have guided a new understanding of the responses of biological systems. Enzymes catalyse reactions by driving the substrate through a high energy species, which is tightly bound to the enzyme. Macromolecular rate theory (MMRT) has recently been developed to account for the changes in the system brought about by this tight binding, specifically the change in the physical parameter heat capacity (ΔCǂp), and the effect this has on the temperature dependence of enzyme reactions. A negative ΔCǂp imparts the signature negative curvature to rates in the absence of denaturation, and finds that Topt, ΔCǂp and curvature are all correlated, placing constraints on biological systems. The simplest of cells comprise thousands of enzymatically catalysed reactions, functioning in series and in parallel in metabolic pathways to determine the overall growth rate of an organism. Intuitively, the temperature effects of enzymes play a role in determining the overall temperature dependence of an organism, in tandem with cellular level regulatory responses. However, the effect of individual Topt values and curvature on overall pathway behaviour is less apparent. Here, this is investigated in the context of MMRT through the in vitro characterisation of a six-step metabolic pathway to understand the steps in isolation and functioning in series. Pathway behaviour is found to be approximately an average of the properties of the

Variations in body morphology explain sex differences in thermoeffector function during compensable heat stress.

Science.gov (United States)

Notley, Sean R; Park, Joonhee; Tagami, Kyoko; Ohnishi, Norikazu; Taylor, Nigel A S

2017-05-01

What is the central question of this study? Can sex-related differences in cutaneous vascular and sudomotor responses be explained primarily by variations in the ratio between body surface area and mass during compensable exercise that elicits equivalent heat-loss requirements and mean body temperature changes across participants? What is the main finding and its importance? Mass-specific surface area was a significant determinant of vasomotor and sudomotor responses in men and women, explaining 10-48% of the individual thermoeffector variance. Nonetheless, after accounting for changes in mean body temperature and morphological differences, sex explained only 5% of that inter-individual variability. It was concluded that sex differences in thermoeffector function are morphologically dependent, but not sex dependent. Sex is sometimes thought to be an independent modulator of cutaneous vasomotor and sudomotor function during heat exposure. Nevertheless, it was hypothesized that, when assessed during compensable exercise that evoked equal heat-loss requirements across participants, sex differences in those thermoeffectors would be explained by variations in the ratio between body surface area and mass (specific surface area). To evaluate that possibility, vasomotor and sudomotor functions were assessed in 60 individuals (36 men and 24 women) with widely varying (overlapping) specific surface areas (range, 232.3-292.7 and 241.2-303.1 cm 2  kg -1 , respectively). Subjects completed two trials in compensable conditions (28°C, 36% relative humidity) involving rest (20 min) and steady-state cycling (45 min) at fixed, area-specific metabolic heat-production rates (light, ∼135 W m -2 ; moderate, ∼200 W m -2 ). Equivalent heat-loss requirements and mean body temperature changes were evoked across participants. Forearm blood flow and vascular conductance were positively related to specific surface area during light work in men (r = 0.67 and r = 0

Insect Sex Determination Manipulated by Their Endosymbionts: Incidences, Mechanisms and Implications.

Science.gov (United States)

Kageyama, Daisuke; Narita, Satoko; Watanabe, Masaya

2012-02-10

The sex-determining systems of arthropods are surprisingly diverse. Some species have male or female heterogametic sex chromosomes while other species do not have sex chromosomes. Most species are diploids but some species, including wasps, ants, thrips and mites, are haplodiploids (n in males; 2n in females). Many of the sexual aberrations, such as sexual mosaics, sex-specific lethality and conversion of sexuality, can be explained by developmental defects including double fertilization of a binucleate egg, loss of a sex chromosome or perturbation of sex-determining gene expression, which occur accidentally or are induced by certain environmental conditions. However, recent studies have revealed that such sexual aberrations can be caused by various groups of vertically-transmitted endosymbiotic microbes such as bacteria of the genera Wolbachia, Rickettsia, Arsenophonus, Spiroplasma and Cardinium, as well as microsporidian protists. In this review, we first summarize the accumulated data on endosymbiont-induced sexual aberrations, and then discuss how such endosymbionts affect the developmental system of their hosts and what kinds of ecological and evolutionary effects these endosymbionts have on their host populations.

Temperature Dependence of Interband Transitions in Wurtzite InP Nanowires.

Science.gov (United States)

Zilli, Attilio; De Luca, Marta; Tedeschi, Davide; Fonseka, H Aruni; Miriametro, Antonio; Tan, Hark Hoe; Jagadish, Chennupati; Capizzi, Mario; Polimeni, Antonio

2015-04-28

Semiconductor nanowires (NWs) formed by non-nitride III-V compounds grow preferentially with wurtzite (WZ) lattice. This is contrary to bulk and two-dimensional layers of the same compounds, where only zincblende (ZB) is observed. The absorption spectrum of WZ materials differs largely from their ZB counterparts and shows three transitions, referred to as A, B, and C in order of increasing energy, involving the minimum of the conduction band and different critical points of the valence band. In this work, we determine the temperature dependence (T = 10-310 K) of the energy of transitions A, B, and C in ensembles of WZ InP NWs by photoluminescence (PL) and PL excitation (PLE) spectroscopy. For the whole temperature and energy ranges investigated, the PL and PLE spectra are quantitatively reproduced by a theoretical model taking into account contribution from both exciton and continuum states. WZ InP is found to behave very similarly to wide band gap III-nitrides and II-VI compounds, where the energy of A, B, and C displays the same temperature dependence. This finding unveils a general feature of the thermal properties of WZ materials that holds regardless of the bond polarity and energy gap of the crystal. Furthermore, no differences are observed in the temperature dependence of the fundamental band gap energy in WZ InP NWs and ZB InP (both NWs and bulk). This result points to a negligible role played by the WZ/ZB differences in determining the deformation potentials and the extent of the electron-phonon interaction that is a direct consequence of the similar nearest neighbor arrangement in the two lattices.

Sex Differences in Behavioral Outcomes Following Temperature Modulation During Induced Neonatal Hypoxic Ischemic Injury in Rats

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Amanda L. Smith

2015-05-01

Full Text Available Neonatal hypoxia ischemia (HI; reduced oxygen and/or blood flow to the brain can cause various degrees of tissue damage, as well as subsequent cognitive/behavioral deficits such as motor, learning/memory, and auditory impairments. These outcomes frequently result from cardiovascular and/or respiratory events observed in premature infants. Data suggests that there is a sex difference in HI outcome, with males being more adversely affected relative to comparably injured females. Brain/body temperature may play a role in modulating the severity of an HI insult, with hypothermia during an insult yielding more favorable anatomical and behavioral outcomes. The current study utilized a postnatal day (P 7 rodent model of HI injury to assess the effect of temperature modulation during injury in each sex. We hypothesized that female P7 rats would benefit more from lowered body temperatures as compared to male P7 rats. We assessed all subjects on rota-rod, auditory discrimination, and spatial/non-spatial maze tasks. Our results revealed a significant benefit of temperature reduction in HI females as measured by most of the employed behavioral tasks. However, HI males benefitted from temperature reduction as measured on auditory and non-spatial tasks. Our data suggest that temperature reduction protects both sexes from the deleterious effects of HI injury, but task and sex specific patterns of relative efficacy are seen.

Sex differences in behavioral outcomes following temperature modulation during induced neonatal hypoxic ischemic injury in rats.

Science.gov (United States)

Smith, Amanda L; Garbus, Haley; Rosenkrantz, Ted S; Fitch, Roslyn Holly

2015-05-22

Neonatal hypoxia ischemia (HI; reduced oxygen and/or blood flow to the brain) can cause various degrees of tissue damage, as well as subsequent cognitive/behavioral deficits such as motor, learning/memory, and auditory impairments. These outcomes frequently result from cardiovascular and/or respiratory events observed in premature infants. Data suggests that there is a sex difference in HI outcome, with males being more adversely affected relative to comparably injured females. Brain/body temperature may play a role in modulating the severity of an HI insult, with hypothermia during an insult yielding more favorable anatomical and behavioral outcomes. The current study utilized a postnatal day (P) 7 rodent model of HI injury to assess the effect of temperature modulation during injury in each sex. We hypothesized that female P7 rats would benefit more from lowered body temperatures as compared to male P7 rats. We assessed all subjects on rota-rod, auditory discrimination, and spatial/non-spatial maze tasks. Our results revealed a significant benefit of temperature reduction in HI females as measured by most of the employed behavioral tasks. However, HI males benefitted from temperature reduction as measured on auditory and non-spatial tasks. Our data suggest that temperature reduction protects both sexes from the deleterious effects of HI injury, but task and sex specific patterns of relative efficacy are seen.

Mapping of five candidate sex-determining loci in rainbow trout (Oncorhynchus mykiss

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Drew Robert E

2009-01-01

Full Text Available Abstract Background Rainbow trout have an XX/XY genetic mechanism of sex determination where males are the heterogametic sex. The homology of the sex-determining gene (SDG in medaka to Dmrt1 suggested that SDGs evolve from downstream genes by gene duplication. Orthologous sequences of the major genes of the mammalian sex determination pathway have been reported in the rainbow trout but the map position for the majority of these genes has not been assigned. Results Five loci of four candidate genes (Amh, Dax1, Dmrt1 and Sox6 were tested for linkage to the Y chromosome of rainbow trout. We exclude the role of all these loci as candidates for the primary SDG in this species. Sox6i and Sox6ii, duplicated copies of Sox6, mapped to homeologous linkage groups 10 and 18 respectively. Genotyping fishes of the OSU × Arlee mapping family for Sox6i and Sox6ii alleles indicated that Sox6i locus might be deleted in the Arlee lineage. Conclusion Additional candidate genes should be tested for their linkage to the Y chromosome. Mapping data of duplicated Sox6 loci supports previously suggested homeology between linkage groups 10 and 18. Enrichment of the rainbow trout genomic map with known gene markers allows map comparisons with other salmonids. Mapping of candidate sex-determining loci is important for analyses of potential autosomal modifiers of sex-determination in rainbow trout.

Temperature dependence of radiation effects in polyethylene

International Nuclear Information System (INIS)

Wu, G; Katsumura, Y.; Kudoh, H.; Morita, Y.; Seguchi, T.

2000-01-01

Temperature dependence of crosslinking and gas evolution under γ-irradiation was studied for high-density and low-density polyethylene samples in the 30-360degC range. It was found that crosslinking was the predominant process up to 300degC and the gel point decreased with increasing temperature. At above 300degC, however, the gel fraction at a given dose decreased rapidly with temperature and the action of radiation turned to enhance polyethylene degradation. Yields of H 2 and hydrocarbon gases increased with temperature and the compositions of hydrocarbons were dose dependent. (author)

The evolution of environmental and genetic sex determination in fluctuating environments.

Science.gov (United States)

Van Dooren, Tom J M; Leimar, Olof

2003-12-01

Twenty years ago, Bulmer and Bull suggested that disruptive selection, produced by environmental fluctuations, can result in an evolutionary transition from environmental sex determination (ESD) to genetic sex determination (GSD). We investigated the feasibility of such a process, using mutation-limited adaptive dynamics and individual-based computer simulations. Our model describes the evolution of a reaction norm for sex determination in a metapopulation setting with partial migration and variation in an environmental variable both within and between local patches. The reaction norm represents the probability of becoming a female as a function of environmental state and was modeled as a sigmoid function with two parameters, one giving the location (i.e., the value of the environmental variable for which an individual has equal chance of becoming either sex) and the other giving the slope of the reaction norm for that environment. The slope can be interpreted as being set by the level of developmental noise in morph determination, with less noise giving a steeper slope and a more switchlike reaction norm. We found convergence stable reaction norms with intermediate to large amounts of developmental noise for conditions characterized by low migration rates, small differential competitive advantages between the sexes over environments, and little variation between individual environments within patches compared to variation between patches. We also considered reaction norms with the slope parameter constrained to a high value, corresponding to little developmental noise. For these we found evolutionary branching in the location parameter and a transition from ESD toward GSD, analogous to the original analysis by Bulmer and Bull. Further evolutionary change, including dominance evolution, produced a polymorphism acting as a GSD system with heterogamety. Our results point to the role of developmental noise in the evolution of sex determination.

Gender/Sex as a Social Determinant of Cardiovascular Risk.

Science.gov (United States)

O'Neil, Adrienne; Scovelle, Anna J; Milner, Allison J; Kavanagh, Anne

2018-02-20

The social gradient for cardiovascular disease (CVD) onset and outcomes is well established. The American Heart Association's Social Determinants of Risk and Outcomes of Cardiovascular Disease Scientific Statement advocates looking beyond breakthroughs in biological science toward a social determinants approach that focuses on socioeconomic position, race and ethnicity, social support, culture and access to medical care, and residential environments to curb the burden of CVD going forward. Indeed, the benefits of this approach are likely to be far reaching, enhancing the positive effects of advances in CVD related to prevention and treatment while reducing health inequities that contribute to CVD onset and outcomes. It is disappointing that the role of gender has been largely neglected despite being a critical determinant of cardiovascular health. It is clear that trajectories and outcomes of CVD differ by biological sex, yet the tendency for sex and gender to be conflated has contributed to the idea that both are constant or fixed with little room for intervention. Rather, as distinct from biological sex, gender is socially produced. Overlaid on biological sex, gender is a broad term that shapes and interacts with one's cognition to guide norms, roles, behaviors, and social relations. It is a fluid construct that varies across time, place, and life stage. Gender can interact with biological sex and, indeed, other social determinants, such as ethnicity and socioeconomic position, to shape cardiovascular health from conception, through early life when health behaviors and risk factors are shaped, into adolescence and adulthood. This article will illustrate how gender shapes the early adoption of health behaviors in childhood, adolescence, and young adulthood by focusing on physical activity, drinking, and smoking behaviors (including the influence of role modeling). We will also discuss the role of gender in psychosocial stress with a focus on trauma from life

The infrared Hall effect in YBCO: Temperature and frequency dependence of Hall scattering

International Nuclear Information System (INIS)

Grayson, M.; Cerne, J.; Drew, H.D.; Schmadel, D.C.; Hughes, R.; Preston, J.S.; Kung, P.J.; Vale, L.

1999-01-01

The authors measure the Hall angle, θ H , in YBCO films in the far- and mid-infrared to determine the temperature and frequency dependence of the Hall scattering. Using novel modulation techniques they measure both the Faraday rotation and ellipticity induced by these films in high magnetic fields to deduce the complex conductivity tensor. They observe a strong temperature dependence of the mid-infrared Hall conductivity in sharp contrast to the weak dependence of the longitudinal conductivity. By fitting the frequency dependent normal state Hall angle to a Lorentzian θ H (ω) = ω H /(γ H minus iω) they find the Hall frequency, ω H , is nearly independent of temperature. The Hall scattering rate, γ H , is consistent with γ H ∼ T 2 up to 200 K and is remarkably independent of IR frequency suggesting non-Fermi liquid behavior

Isotopic dependence of the fragments' internal temperatures determined from multifragment emission

Science.gov (United States)

Souza, S. R.; Donangelo, R.

2018-05-01

The internal temperatures of fragments produced by an excited nuclear source are investigated by using the microcanonical version of the statistical multifragmentation model, with discrete energy. We focus on the fragments' properties at the breakup stage, before they have time to deexcite by particle emission. Since the adopted model provides the excitation energy distribution of these primordial fragments, it allows one to calculate the temperatures of different isotope families and to make inferences about the sensitivity to their isospin composition. It is found that, due to the functional form of the nuclear density of states and the excitation energy distribution of the fragments, proton-rich isotopes are hotter than neutron-rich isotopes. This property has been taken to be an indication of earlier emission of the former from a source that cools down as it expands and emits fragments. Although this scenario is incompatible with the prompt breakup of a thermally equilibrated source, our results reveal that the latter framework also provides the same qualitative features just mentioned. Therefore they suggest that this property cannot be taken as evidence for nonequilibrium emission. We also found that this sensitivity to the isotopic composition of the fragments depends on the isospin composition of the source, and that it is weakened as the excitation energy of the source increases.

Temperature dependences of photoconductivity of CdHgTe crystals with photoactive inclusions

International Nuclear Information System (INIS)

Vlasenko, A.I.; Vlasenko, Z.K.

1999-01-01

Temperature dependences of life time τ and spectral characteristics of photoconductivity for Cd x Hg 1-x Te crystals (x = 0.2) with photoactive inclusions are investigated. It is shown that the N-type character of effective lifetime temperature dependences in nonhomogeneous crystals, in particular, its sharp temperature activation in the region of transition from the impurity to the intrinsic conductivity is determined by not the Shockley-Read mechanism, but by the interband impact mechanism with changing effective geometrical sizes of recombination active regions under temperature increase. Within the frames of this model the smoothing of the non-monotone character of the photoconductivity spectral characteristics in the region of fundamental absorption under the heating is explained. The calculation results that are in qualitative agreement with the experimental data are presented [ru

Sex Determination of Japanese Quails (Coturnix Coturnix Japonica using with Zoometric Measurements

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Tülin Çiçek Rathert

2017-09-01

Full Text Available The difficulty of sex determination in most poultry species causes significant financial losses for poultry production as birds cannot be separated at early stages of growth for meat or egg production. Therefore it is important to determine bird’s sex with zoometric parameters. This study was carried out to determine the sex of Japanese quails with zoometric measurements, such as live weight, body length, chest depth and chest width. Eighty-eight male and female Japanese quail chicks were used individually for live weight, chest depth (mm, chest width (mm and body length (mm with using digital scaled balance and caliper for every week over a period of six weeks. The weekly collected data were applied to t test for estimating the sex discrimination. The Pearson’s correlation was applied for examining the interrelationship between sex and biometric traits. The results indicated that there was a significant positive correlation between live weight and body length beginning with the 2nd week. Therefore, zoometric measurement of these body traits is suitable for discriminating the sex of Japanese quails in early phase of life.

Determination of Temperature-Dependent Stress State in Thin AlGaN Layer of AlGaN/GaN HEMT Heterostructures by Near-Resonant Raman Scattering

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Yanli Liu

2015-01-01

Full Text Available The temperature-dependent stress state in the AlGaN barrier layer of AlGaN/GaN heterostructure grown on sapphire substrate was investigated by ultraviolet (UV near-resonant Raman scattering. Strong scattering peak resulting from the A1(LO phonon mode of AlGaN is observed under near-resonance condition, which allows for the accurate measurement of Raman shifts with temperature. The temperature-dependent stress in the AlGaN layer determined by the resonance Raman spectra is consistent with the theoretical calculation result, taking lattice mismatch and thermal mismatch into account together. This good agreement indicates that the UV near-resonant Raman scattering can be a direct and effective method to characterize the stress state in thin AlGaN barrier layer of AlGaN/GaN HEMT heterostructures.

Effective size of density-dependent two-sex populations: the effect of mating systems.

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Myhre, A M; Engen, S; SAEther, B-E

2017-08-01

Density dependence in vital rates is a key feature affecting temporal fluctuations of natural populations. This has important implications for the rate of random genetic drift. Mating systems also greatly affect effective population sizes, but knowledge of how mating system and density regulation interact to affect random genetic drift is poor. Using theoretical models and simulations, we compare N e in short-lived, density-dependent animal populations with different mating systems. We study the impact of a fluctuating, density-dependent sex ratio and consider both a stable and a fluctuating environment. We find a negative relationship between annual N e /N and adult population size N due to density dependence, suggesting that loss of genetic variation is reduced at small densities. The magnitude of this decrease was affected by mating system and life history. A male-biased, density-dependent sex ratio reduces the rate of genetic drift compared to an equal, density-independent sex ratio, but a stochastic change towards male bias reduces the N e /N ratio. Environmental stochasticity amplifies temporal fluctuations in population size and is thus vital to consider in estimation of effective population sizes over longer time periods. Our results on the reduced loss of genetic variation at small densities, particularly in polygamous populations, indicate that density regulation may facilitate adaptive evolution at small population sizes. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Temperature dependence of the magnetization of canted spin structures

DEFF Research Database (Denmark)

Jacobsen, Henrik; Lefmann, Kim; Brok, Erik

2012-01-01

Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models for the ......Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models...... for the temperature dependence of the magnetization of a simple canted spin structure in which relaxation can take place at finite temperatures between spin configurations with different canting angles. We show that the saturation magnetization may either decrease or increase with decreasing temperature, depending...

Identification of Sex-determining Loci in Pacific White Shrimp Litopeneaus vannamei Using Linkage and Association Analysis.

Science.gov (United States)

Yu, Yang; Zhang, Xiaojun; Yuan, Jianbo; Wang, Quanchao; Li, Shihao; Huang, Hao; Li, Fuhua; Xiang, Jianhai

2017-06-01

The Pacific white shrimp Litopenaeus vannamei is a predominant aquaculture shrimp species in the world. Like other animals, the L. vannamei exhibited sexual dimorphism in growth trait. Mapping of the sex-determining locus will be very helpful to clarify the sex determination system and further benefit the shrimp aquaculture industry towards the production of mono-sex stocks. Based on the data used for high-density linkage map construction, linkage-mapping analysis was conducted. The sex determination region was mapped in linkage group (LG) 18. A large region from 0 to 21.205 cM in LG18 showed significant association with sex. However, none of the markers in this region showed complete association with sex in the other populations. So an association analysis was designed using the female parent, pool of female progenies, male parent, and pool of male progenies. Markers were de novo developed and those showing significant differences between female and male pools were identified. Among them, three sex-associated markers including one fully associated marker were identified. Integration of linkage and association analysis showed that the sex determination region was fine-mapped in a small region along LG18. The identified sex-associated marker can be used for the sex detection of this species at genetic level. The fine-mapped sex-determining region will contribute to the mapping of sex-determining gene and help to clarify sex determination system for L. vannamei.

Temperature and angular dependence of substrate response in SEGR

International Nuclear Information System (INIS)

Mouret, I.; Allenspach, M.; Schrimpf, R.D.; Brews, J.R.; Galloway, K.F.

1994-01-01

This work examines the role of the substrate response in determining the temperature and angular dependence of Single-Event Gate Rupture (SEGR). Experimental data indicate that the likelihood of SEGR increases when the temperature of the device is increased or when the incident angle is made closer to normal. In this work, simulations are used to explore this influence of high temperature on SEGR and to support physical explanations for this effect. The reduced hole mobility at high temperature causes the hole concentration at the oxide-silicon interface to be greater, increasing the transient oxide field near the strike position. In addition, numerical calculations show that the transient oxide field decreases as the ion's angle of incidence is changed from normal. This decreased field suggests a lowered likelihood for SEGR, in agreement with the experimental trend

Mental health disorders among homeless, substance-dependent men who have sex with men.

Science.gov (United States)

Fletcher, Jesse B; Reback, Cathy J

2017-07-01

Homelessness is associated with increased prevalence of mental health disorders, substance use disorders and mental health/substance use disorder comorbidity in the United States of America. Gay, bisexual and other men who have sex with men (MSM) living in the United States are at increased risk for homelessness, and have also evidenced elevated mental health and substance use disorder prevalence relative to their non-MSM male counterparts. Secondary analysis of data from a randomised controlled trial estimating the diagnostic prevalence of substance use/mental health disorder comorbidity among a sample of homeless, substance-dependent MSM (DSM-IV verified; n = 131). The most prevalent substance use/mental health disorder comorbidities were stimulant dependence comorbid with at least one depressive disorder (28%), alcohol dependence comorbid with at least one depressive disorder (26%) and stimulant dependence comorbid with antisocial personality disorder (25%). Diagnostic depression and antisocial personality disorder both demonstrated high rates of prevalence among homeless, substance-dependent (particularly stimulant and alcohol dependent) MSM. [Fletcher JB, Reback CJ. Mental health disorders among homeless, substance-dependent men who have sex with men. Drug Alcohol Rev 2016;36:555-559]. © 2016 Australasian Professional Society on Alcohol and other Drugs.

Modeling and Compensating Temperature-Dependent Non-Uniformity Noise in IR Microbolometer Cameras

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Alejandro Wolf

2016-07-01

Full Text Available Images rendered by uncooled microbolometer-based infrared (IR cameras are severely degraded by the spatial non-uniformity (NU noise. The NU noise imposes a fixed-pattern over the true images, and the intensity of the pattern changes with time due to the temperature instability of such cameras. In this paper, we present a novel model and a compensation algorithm for the spatial NU noise and its temperature-dependent variations. The model separates the NU noise into two components: a constant term, which corresponds to a set of NU parameters determining the spatial structure of the noise, and a dynamic term, which scales linearly with the fluctuations of the temperature surrounding the array of microbolometers. We use a black-body radiator and samples of the temperature surrounding the IR array to offline characterize both the constant and the temperature-dependent NU noise parameters. Next, the temperature-dependent variations are estimated online using both a spatially uniform Hammerstein-Wiener estimator and a pixelwise least mean squares (LMS estimator. We compensate for the NU noise in IR images from two long-wave IR cameras. Results show an excellent NU correction performance and a root mean square error of less than 0.25 ∘ C, when the array’s temperature varies by approximately 15 ∘ C.

Temperature dependence of elastic properties of paratellurite

International Nuclear Information System (INIS)

Silvestrova, I.M.; Pisarevskii, Y.V.; Senyushenkov, P.A.; Krupny, A.I.

1987-01-01

New data are presented on the temperature dependence of the elastic wave velocities, elastic stiffness constants, and thermal expansion of paratellurite. It is shown that the external pressure appreciably influences the elastic properties of TeO 2 , especially the temperature dependence of the elastic modulus connected with the crystal soft mode. (author)

A timecourse analysis of systemic and gonadal effects of temperature on sexual development of the red-eared slider turtle Trachemys scripta elegans.

Science.gov (United States)

Czerwinski, Michael; Natarajan, Anirudh; Barske, Lindsey; Looger, Loren L; Capel, Blanche

2016-12-01

Temperature dependent sex determination (TSD) is the process by which the environmental temperature experienced during embryogenesis influences the sex of an organism, as in the red-eared slider turtle Trachemys scripta elegans. In accord with current paradigms of vertebrate sex determination, temperature is believed to exert its effects on sexual development in T. scripta entirely within the middle third of development, when the gonad is forming. However, whether temperature regulates the transcriptome in T. scripta early embryos in a manner that could influence secondary sex characteristics or establish a pro-male or pro-female environment has not been investigated. In addition, apart from a handful of candidate genes, very little is known about potential similarities between the expression cascade during TSD and the genetic cascade that drives mammalian sex determination. Here, we conducted an unbiased transcriptome-wide analysis of the effects of male- and female-promoting temperatures on the turtle embryo prior to gonad formation, and on the gonad during the temperature sensitive period. We found sexually dimorphic expression reflecting differences in steroidogenic enzymes and brain development prior to gonad formation. Within the gonad, we mapped a cascade of differential expression similar to the genetic cascade established in mammals. Using a Hidden Markov Model based clustering approach, we identified groups of genes that show heterochronic shifts between M. musculus and T. scripta. We propose a model in which multiple factors influenced by temperature accumulate during early gonadogenesis, and converge on the antagonistic regulation of aromatase to canalize sex determination near the end of the temperature sensitive window of development. Copyright © 2016 Elsevier Inc. All rights reserved.

Temperature dependence of sound velocity in yttrium ferrite

International Nuclear Information System (INIS)

L'vov, V.A.

1979-01-01

The effect of the phonon-magnon and phonon-phonon interoctions on the temperature dependence of the longitudinal sound velocity in yttrium ferrite is considered. It has been shown that at low temperatures four-particle phonon-magnon processes produce the basic contribution to renormalization of the sound velocity. At higher temperatures the temperature dependence of the sound velocity is mainly defined by phonon-phonon processes

Temperature dependence of nitrogen solubility in iron base multicomponent melts

International Nuclear Information System (INIS)

Sokolov, V.M.; Koval'chuk, L.A.

1986-01-01

Method for calculating temperature dependence of nitrogen solubility in iron base multicomponent melts is suggested. Application areas of existing methods were determined and advantages of the new method for calculating nitrogen solubility in multicomponent-doped iron melts (Fe-Ni-Cr-Mo, Fe-Ni-Cr-Mn, Fe-Mo-V) at 1773-2073 K are shown

Sex determination based on a thoracic vertebra and ribs evaluation using clinical chest radiography.

Science.gov (United States)

Tsubaki, Shun; Morishita, Junji; Usumoto, Yosuke; Sakaguchi, Kyoko; Matsunobu, Yusuke; Kawazoe, Yusuke; Okumura, Miki; Ikeda, Noriaki

2017-07-01

Our aim was to investigate whether sex can be determined from a combination of geometric features obtained from the 10th thoracic vertebra, 6th rib, and 7th rib. Six hundred chest radiographs (300 males and 300 females) were randomly selected to include patients of six age groups (20s, 30s, 40s, 50s, 60s, and 70s). Each group included 100 images (50 males and 50 females). A total of 14 features, including 7 lengths, 5 indices for the vertebra, and 2 types of widths for ribs, were utilized and analyzed for sex determination. Dominant features contributing to sex determination were selected by stepwise discriminant analysis after checking the variance inflation factors for multicollinearity. The accuracy of sex determination using a combination of the vertebra and ribs was evaluated from the selected features by the stepwise discriminant analysis. The accuracies in each age group were also evaluated in this study. The accuracy of sex determination based on a combination of features of the vertebra and ribs was 88.8% (533/600). This performance was superior to that of the vertebra or ribs only. Moreover, sex determination of subjects in their 20s demonstrated the highest accuracy (96.0%, 96/100). The features selected in the stepwise discriminant analysis included some features in both the vertebra and ribs. These results indicate the usefulness of combined information obtained from the vertebra and ribs for sex determination. We conclude that a combination of geometric characteristics obtained from the vertebra and ribs could be useful for determining sex. Copyright © 2017 Elsevier B.V. All rights reserved.

Single-locus complementary sex determination in the inbreeding wasp Euodynerus foraminatus Saussure (Hymenoptera: Vespidae).

Science.gov (United States)

Stahlhut, J K; Cowan, D P

2004-03-01

The Hymenoptera have arrhenotokous haplodiploidy in which males normally develop from unfertilized eggs and are haploid, while females develop from fertilized eggs and are diploid. Multiple sex determination systems are known to underlie haplodiploidy, and the best understood is single-locus complementary sex determination (sl-CSD) in which sex is determined at a single polymorphic locus. Individuals heterozygous at the sex locus develop as females; individuals that are hemizygous (haploid) or homozygous (diploid) at the sex locus develop as males. sl-CSD can be detected with inbreeding experiments that produce diploid males in predictable proportions as well as sex ratio shifts due to diploid male production. This sex determination system is considered incompatible with inbreeding because the ensuing increase in homozygosity increases the production of diploid males that are inviable or infertile, imposing a high cost on matings between close relatives. However, in the solitary hunting wasp Euodynerus foraminatus, a species suspected of having sl-CSD, inbreeding may be common due to a high incidence of sibling matings at natal nests. In laboratory crosses with E. foraminatus, we find that sex ratios and diploid male production (detected as microsatellite heterozygosity) are consistent with sl-CSD, but not with other sex determination systems. This is the first documented example of sl-CSD in a hymenopteran with an apparent natural history of inbreeding, and thus presents a paradox for our understanding of hymenopteran genetics.

How is sex determined in insects? An epilogue

Indian Academy of Sciences (India)

transcriptional factors, which bring about sexual dimorphism in adult flies. ... sex determination, in response to both internal and external selection forces. ... such as in the control of pests (e.g. C. capitata) and vectors of human diseases.

Convergent evolution of chromosomal sex-determining regions in the animal and fungal kingdoms.

Directory of Open Access Journals (Sweden)

James A Fraser

2004-12-01

Full Text Available Sexual identity is governed by sex chromosomes in plants and animals, and by mating type (MAT loci in fungi. Comparative analysis of the MAT locus from a species cluster of the human fungal pathogen Cryptococcus revealed sequential evolutionary events that fashioned this large, highly unusual region. We hypothesize that MAT evolved via four main steps, beginning with acquisition of genes into two unlinked sex-determining regions, forming independent gene clusters that then fused via chromosomal translocation. A transitional tripolar intermediate state then converted to a bipolar system via gene conversion or recombination between the linked and unlinked sex-determining regions. MAT was subsequently subjected to intra- and interallelic gene conversion and inversions that suppress recombination. These events resemble those that shaped mammalian sex chromosomes, illustrating convergent evolution in sex-determining structures in the animal and fungal kingdoms.

Temperature dependency of silicon structures for magnetic field gradient sensing

Science.gov (United States)

Dabsch, Alexander; Rosenberg, Christoph; Stifter, Michael; Keplinger, Franz

2018-02-01

This work describes the temperature dependence of two sensors for magnetic field gradient sensors and demonstrates a structure to compensate for the drift of resonance frequency over a wide temperature range. The temperature effect of the sensing element is based on internal stresses induced by the thermal expansion of material, therefore FEM is used to determine the change of the eigenvalues of the sensing structure. The experimental setup utilizes a Helmholtz coil system to generate the magnetic field and to excite the MEMS structure with Lorentz forces. The MEMS structure is placed on a plate heated with resistors and cooled by a Peltier element to control the plate temperature. In the second part, we describe how one can exploit temperature sensitivity for temperature measurements and we show the opportunity to include the temperature effect to increase the sensitivity of single-crystal silicon made flux density gradient sensors.

Sex determination of Pohnpei Micronesian kingfishers using morphological and molecular genetic techniques

Science.gov (United States)

Kesler, Dylan C.; Lopes, I.F.; Haig, Susan M.

2006-01-01

Conservation-oriented studies of Micronesian Kingfishers (Todiramphus cinnamominus) have been hindered by a lack of basic natural history information, despite the status of the Guam subspecies (T. c. cinnamominus) as one of the most endangered species in the world. We used tissue samples and morphometric measures from museum specimens and wild-captured Pohnpei Micronesian Kingfishers (T. c. reichenbachii) to develop methods for sex determination. We present a modified molecular protocol and a discriminant function that yields the probability that a particular individual is male or female. Our results revealed that females were significantly larger than males, and the discriminant function correctly predicted sex in 73% (30/41) of the individuals. The sex of 86% (18/21) of individuals was correctly assigned when a moderate reliability threshold was set. Sex determination using molecular genetic techniques was more reliable than methods based on morphology. Our results will facilitate recovery efforts for the critically endangered Guam Micronesian Kingfisher and provide a basis for sex determination in the 11 other endangered congeners in the Pacific Basin.

Temperature dependent electrical characteristics of Zn/ZnSe/n-GaAs/In structure

Science.gov (United States)

Sağlam, M.; Güzeldir, B.

2016-04-01

We have reported a study of the I-V characteristics of Zn/ZnSe/n-GaAs/In sandwich structure in a wide temperature range of 80-300 K by a step of 20 K, which are prepared by Successive Ionic Layer Adsorption and Reaction (SILAR) method. The main electrical parameters, such as ideality factor and zero-bias barrier height determined from the forward bias I-V characteristics were found strongly depend on temperature and when the increased, the n decreased with increasing temperature. The ideality factor and barrier height values as a function of the sample temperature have been attributed to the presence of the lateral inhomogeneities of the barrier height. Furthermore, the series resistance have been calculated from the I-V measurements as a function of temperature dependent.

Temperature dependent anomalous statistics

International Nuclear Information System (INIS)

Das, A.; Panda, S.

1991-07-01

We show that the anomalous statistics which arises in 2 + 1 dimensional Chern-Simons gauge theories can become temperature dependent in the most natural way. We analyze and show that a statistic's changing phase transition can happen in these theories only as T → ∞. (author). 14 refs

Temperature-dependent infrared optical properties of 3C-, 4H- and 6H-SiC

Science.gov (United States)

Tong, Zhen; Liu, Linhua; Li, Liangsheng; Bao, Hua

2018-05-01

The temperature-dependent optical properties of cubic (3C) and hexagonal (4H and 6H) silicon carbide are investigated in the infrared range of 2-16 μm both by experimental measurements and numerical simulations. The temperature in experimental measurement is up to 593 K, while the numerical method can predict the optical properties at elevated temperatures. To investigate the temperature effect, the temperature-dependent damping parameter in the Lorentz model is calculated based on anharmonic lattice dynamics method, in which the harmonic and anharmonic interatomic force constants are determined from first-principles calculations. The infrared phonon modes of silicon carbide are determined from first-principles calculations. Based on first-principles calculations, the Lorentz model is parameterized without any experimental fitting data and the temperature effect is considered. In our investigations, we find that the increasing temperature induces a small reduction of the reflectivity in the range of 10-13 μm. More importantly, it also shows that our first-principles calculations can predict the infrared optical properties at high-temperature effectively which is not easy to be obtained through experimental measurements.

Genetic sex determination and extinction.

Science.gov (United States)

Hedrick, Philip W; Gadau, Jürgen; Page, Robert E

2006-02-01

Genetic factors can affect the probability of extinction either by increasing the effect of detrimental variants or by decreasing the potential for future adaptive responses. In a recent paper, Zayed and Packer demonstrate that low variation at a specific locus, the complementary sex determination (csd) locus in Hymenoptera (ants, bees and wasps), can result in a sharply increased probability of extinction. Their findings illustrate situations in which there is a feedback process between decreased genetic variation at the csd locus owing to genetic drift and decreased population growth, resulting in an extreme type of extinction vortex for these ecologically important organisms.

Temperature dependence of energy-transducing functions and inhibitor sensitivity in chloroplasts

Energy Technology Data Exchange (ETDEWEB)

Schuurmans, J.J.; Veerman, E.C.I.; Francke, J.A.; Torres-Pereira, J.M.G.; Kraayenhof, R.

1984-01-01

A comparative analysis of the temperature dependence of energy-transducing reactions in spinach (Spinacia oleracea) chloroplasts and their sensitivity for uncouplers and energy-transfer inhibitors at different temperatures is presented. Arrhenius plots reveal two groups of transitions, around 19/sup 0/C and around 12/sup 0/C. Activities that show transitions around 19/sup 0/C include linear electron flow from water to ferricyanide, its coupled photophosphorylation, the dark-release of the fluorescent probe atebrin, and the slow component of the 515 nm (carotenoid) absorbance decay after a flash. The transitions around 12/sup 0/C are observed with pyocyanine-mediated cyclic photophosphorylation, light- and dithioerythritol-activated ATP hydrolysis, the dark-release of protons, and the fast 515 nm decay component. It is suggested that both groups of temperature transitions are determined by proton displacements in different domains of the exposed thylakoid membranes. The effects of various uncouplers and an energy-transfer inhibitor are temperature dependent. Some uncouplers also show a different relative inhibition of proton uptake and ATP synthesis at lower temperatures. The efficiency of energy transduction (ATP/e/sub 3/) varied with temperature and was optimal around 10/sup 0/C.

Absence of complementary sex determination in the parasitoid wasp genus asobara (hymenoptera: braconidae)

NARCIS (Netherlands)

Ma, W.J.; Kuijper, B.; Boer, de J.G.; Zande, van de L.; Beukeboom, L.W.; Wertheim, B.; Pannebakker, B.A.

2013-01-01

An attractive way to improve our understanding of sex determination evolution is to study the underlying mechanisms in closely related species and in a phylogenetic perspective. Hymenopterans are well suited owing to the diverse sex determination mechanisms, including different types of

Absence of complementary sex determination in the parasitoid wasp genus Asobara (Hymenoptera: Braconidae)

NARCIS (Netherlands)

Ma, Wen-Juan; Kuijper, Bram; de Boer, Jetske G.; van de Zande, Louis; Beukeboom, Leo W.; Wertheim, Bregje; Pannebakker, Bart A.

2013-01-01

An attractive way to improve our understanding of sex determination evolution is to study the underlying mechanisms in closely related species and in a phylogenetic perspective. Hymenopterans are well suited owing to the diverse sex determination mechanisms, including different types of

Genetic sex determination in Astatotilapia calliptera, a prototype species for the Lake Malawi cichlid radiation

Science.gov (United States)

Peterson, Erin N.; Cline, Maggie E.; Moore, Emily C.; Roberts, Natalie B.; Roberts, Reade B.

2017-06-01

East African cichlids display extensive variation in sex determination systems. The species Astatotilapia calliptera is one of the few cichlids that reside both in Lake Malawi and in surrounding waterways. A. calliptera is of interest in evolutionary studies as a putative immediate outgroup species for the Lake Malawi species flock and possibly as a prototype ancestor-like species for the radiation. Here, we use linkage mapping to test association of sex in A. calliptera with loci that have been previously associated with genetic sex determination in East African cichlid species. We identify a male heterogametic XY system segregating at linkage group (LG) 7 in an A. calliptera line that originated from Lake Malawi, at a locus previously shown to act as an XY sex determination system in multiple species of Lake Malawi cichlids. Significant association of genetic markers and sex produce a broad genetic interval of approximately 26 megabases (Mb) using the Nile tilapia genome to orient markers; however, we note that the marker with the strongest association with sex is near a gene that acts as a master sex determiner in other fish species. We demonstrate that alleles of the marker are perfectly associated with sex in Metriaclima mbenjii, a species from the rock-dwelling clade of Lake Malawi. While we do not rule out the possibility of other sex determination loci in A. calliptera, this study provides a foundation for fine mapping of the cichlid sex determination gene on LG7 and evolutionary context regarding the origin and persistence of the LG7 XY across diverse, rapidly evolving lineages.

Temperature dependence of autoxidation of perilla oil and tocopherol degradation.

Science.gov (United States)

Wang, Seonyeong; Hwang, Hyunsuk; Yoon, Sukhoo; Choe, Eunok

2010-08-01

Temperature dependence of the autoxidation of perilla oil and tocopherol degradation was studied with corn oil as a reference. The oils were oxidized in the dark at 20, 40, 60, and 80 degrees C. Oil oxidation was determined by peroxide and conjugated dienoic acid values. Tocopherols in the oils were quantified by HPLC. The oxidation of both oils increased with oxidation time and temperature. Induction periods for oil autoxidation decreased with temperature, and were longer in corn oil than in perilla oil, indicating higher sensitivity of perilla oil to oxidation. However, time lag for tocopherol degradation was longer in perilla oil, indicating higher stability of tocopherols in perilla oil than in corn oil. Activation energies for oil autoxidation and tocopherol degradation were higher in perilla oil (23.9 to 24.2, 9.8 kcal/mol, respectively) than in corn oil (12.5 to 15.8, 8.8 kcal/mol, respectively) indicating higher temperature-dependence in perilla oil. Higher stability of tocopherols in perilla oil was highly related with polyphenols. The study suggests that more careful temperature control is required to decrease the autoxidation of perilla oil than that of corn oil, and polyphenols contributed to the oxidative stability of perilla oil by protecting tocopherols from degradation, especially at the early stage of oil autoxidation.

Luminescence lifetimes in quartz: dependence on annealing temperature prior to beta irradiation

International Nuclear Information System (INIS)

Galloway, R.B.

2002-01-01

It is well known that the thermal history of a quartz sample influences the optically stimulated luminescence sensitivity of the quartz. It is found that the optically stimulated luminescence lifetime, determined from time resolved spectra obtained with pulsed stimulation, also depends on past thermal treatment. For samples at 20 deg. C during stimulation, the lifetime depends on beta dose and on duration of preheating at 220 deg. C prior to stimulation for quartz annealed at 600 deg. C and above, but is independent of these factors for quartz annealed at 500 deg. C and below. For stimulation at higher temperatures, the lifetime becomes shorter if the sample is held at temperatures above 125 deg. C during stimulation, in a manner consistent with thermal quenching. A single exponential decay is all that is required to fit the time resolved spectra for un-annealed quartz regardless of the temperature during stimulation (20-175 deg. C), or to fit the time resolved spectra from all samples held at 20 deg. C during stimulation, regardless of annealing temperature (20-1000 deg. C). An additional shorter lifetime is found for some combinations of annealing temperature and temperature during stimulation. The results are discussed in terms of a model previously used to explain thermal sensitisation. The luminescence lifetime data are best explained by the presence of two principal luminescence centres, their relative importance depending on the annealing temperature, with a third centre involved for limited combinations of annealing temperature and temperature during stimulation

Investigation Of Temperature Dependent Characteristics Of ...

African Journals Online (AJOL)

The structure, magnetization and magnetostriction of Laves phase compound TbCo2 were investigated by temperature dependent high resolution neutron powder diffraction. The compound crystallizes in the cubic Laves phase C15 structure above its Curie temperature, TC and exhibits a rhombohedral distortion (space ...

Estimation of the temperature dependent interaction between uncharged point defects in Si

Energy Technology Data Exchange (ETDEWEB)

Kamiyama, Eiji [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja-shi, Okayama-ken 719-1197 (Japan); GlobalWafers Japan Co., Ltd., 30 Soya, Hadano, Kanagawa, 257-8566 (Japan); Vanhellemont, Jan [Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, Ghent B-9000 (Belgium); Sueoka, Koji [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja-shi, Okayama-ken 719-1197 (Japan)

2015-01-15

A method is described to estimate the temperature dependent interaction between two uncharged point defects in Si based on DFT calculations. As an illustration, the formation of the uncharged di-vacancy V{sub 2} is discussed, based on the temperature dependent attractive field between both vacancies. For that purpose, all irreducible configurations of two uncharged vacancies are determined, each with their weight given by the number of equivalent configurations. Using a standard 216-atoms supercell, nineteen irreducible configurations of two vacancies are obtained. The binding energies of all these configurations are calculated. Each vacancy is surrounded by several attractive sites for another vacancy. The obtained temperature dependent of total volume of these attractive sites has a radius that is closely related with the capture radius for the formation of a di-vacancy that is used in continuum theory. The presented methodology can in principle also be applied to estimate the capture radius for pair formation of any type of point defects.

Development of a temperature-dependent cyclic plasticity constitutive model for SUS304 steel

International Nuclear Information System (INIS)

Takahashi, Yukio

1990-01-01

Development of an accurate inelastic constitutive model is required to improve the accuracy of inelastic analysis for structural components used in the inelastic region. Based on two fundamental assumptions derived from physical interpretation of temperature dependency of the plastic deformation behavior of type 304 stainless steel, a temperature-dependent cyclic plastic constitutive model is constructed here. Particular emphasis is placed on the modeling of enhanced hardening caused by the dynamic strain aging effect observed in some temperature regimes. Constants and functions involved in the model are determined based on the deformation characteristics observed in the low-cycle fatigue tests conducted at room temperature through 600degC. Several comparisons of model predictions with experimental data show the effectiveness of the present model in non-isothermal condition as well as in isothermal condition between room temperature and 600degC. (author)

Validation and use of DNA markers for sex determination in papaya (Carica papaya)

International Nuclear Information System (INIS)

Ejaz, M.; Iqbal, M.; Ahmed, I.

2015-01-01

Profitable papaya production requires female and hermaphrodite plants in higher number than male plants. This is only possible if sex of plants is determined at an early growth stage. The present study was conducted to validate sex-linked DNA markers using plants from two Pakistani papaya varieties and subsequently utilize them for determination of sex in juvenile papaya plants. One hundred and five plants (including 49 male and 56 female) of two Pakistani Papaya varieties at flowering stage were screened with six DNA markers viz., W-11, T12, SDP, Napf-76Napf-76, PKBT4 and PKBT5. All male plants exhibited amplification of sex-linked alleles with markers T12 and W11, whereas, 96% and 95% of female plants showed the absence of sex-linked allele with these markers, respectively. Markers SDP, PKBT5 and Napf-76 showed the presence of sex-linked alleles in 98%, 96% and 93% of male plants, respectively, whereas the same markers showed the absence of sex-linked alleles in 100%, 96% and 94% of female plants. One marker, PKBT4 could not produce expected PCR amplification reported previously. The five DNA markers were further used to screen 171 papaya seedlings. These markers clearly differentiated male and female sex types in the studied papaya plants. Results of our study are likely to facilitate Pakistani papaya breeders and growers to incorporate DNA based screening at juvenile stage to determine sex at early stage and to ensure profitable papaya production. (author)

Lipid- and temperature-dependent structural changes in Acholeplasma laidlawii cell membrances

Energy Technology Data Exchange (ETDEWEB)

James, R.; Branton, D.

1973-01-01

The lipids in cell membranes of Acholeplasma laidlawii were enriched with different fatty acids selected to produce membranes showing molecular motion discontinuities at temperatures between 10 and 35/sup 0/C. Molecular motion in these membranes was probed by ESR after labelling with 12-nitroxide stearate, and structure in these membranes was examined by electron microscopy after freeze-etching. Freeze-etching and electron microscopy showed that under certain conditions the particles in the A. laidlawii membranes aggregated, resulting in particle-rich and particle-depleted regions in the cell membrane. Depending upon the lipid content of the membrane, this aggregation could begin at temperatures well above the ESR-determined discontinuity. Aggregation increased with decreasing temperature but was completed at or near the discontinuity. However, cell membranes grown and maintained well below their ESR-determined discontinuity did not show maximum particle aggregation until after they had been exposed to temperatures at or above the discontinuity. The results show that temperatures at or near a phase transition temperature can induce aggregation of the membrane particles. This suggests that temperature-induced changes in the lipid phase of a biological membrane can induce phase separations which affect the topography of associated proteins.

Sox9 gene regulation and the loss of the XY/XX sex-determining mechanism in the mole vole Ellobius lutescens.

Science.gov (United States)

Bagheri-Fam, Stefan; Sreenivasan, Rajini; Bernard, Pascal; Knower, Kevin C; Sekido, Ryohei; Lovell-Badge, Robin; Just, Walter; Harley, Vincent R

2012-01-01

In most mammals, the Y chromosomal Sry gene initiates testis formation within the bipotential gonad, resulting in male development. SRY is a transcription factor and together with SF1 it directly up-regulates the expression of the pivotal sex-determining gene Sox9 via a 1.3-kb cis-regulatory element (TESCO) which contains an evolutionarily conserved region (ECR) of 180 bp. Remarkably, several rodent species appear to determine sex in the absence of Sry and a Y chromosome, including the mole voles Ellobius lutescens and Ellobius tancrei, whereas Ellobius fuscocapillus of the same genus retained Sry. The sex-determining mechanisms in the Sry-negative species remain elusive. We have cloned and sequenced 1.1 kb of E. lutescens TESCO which shares 75% sequence identity with mouse TESCO indicating that testicular Sox9 expression in E. lutescens might still be regulated via TESCO. We have also cloned and sequenced the ECRs of E. tancrei and E. fuscocapillus. While the three Ellobius ECRs are highly similar (94-97% sequence identity), they all display a 14-bp deletion (Δ14) removing a highly conserved SOX/TCF site. Introducing Δ14 into mouse TESCO increased both basal activity and SF1-mediated activation of TESCO in HEK293T cells. We propose a model whereby Δ14 may have triggered up-regulation of Sox9 in XX gonads leading to destabilization of the XY/XX sex-determining mechanism in Ellobius. E. lutescens/E. tancrei and E. fuscocapillus could have independently stabilized their sex determination mechanisms by Sry-independent and Sry-dependent approaches, respectively.

Temperature dependence of mobility in silicon (100) inversion layers at low temperatures

International Nuclear Information System (INIS)

Kawaguchi, Y.; Suzuki, T.; Kawaji, S.

1982-01-01

Electron mobility of Si(100) n-inversion layers in MOSFETs having μsub(peak) (4.2 K) = 4000.6500 and 12000 cm 2 /V x s has been measured at temperatures between 1 and 80 K. The carrier concentration dependence of the mobility extrapolated to T = O and the temperature dependent part of the scattering probability are investigated. (orig.)

A simple model for the determination of L0, D and τ in a semiconductor and their temperature dependence

International Nuclear Information System (INIS)

Ahmed, F.

1989-07-01

It is very important to characterize the quality of a semiconductor material before it is processed into a device. Diffusion length L 0 , diffusion constant D and carrier lifetime τ of minority carriers are some of the parameters which play a vital role in determining the quality of a semiconductor material. Recently Ahmed and co-workers have shown that by measuring the frequency response of a time varying (e iwt ) light (or electron) beam one can determine all the important parameters including the absorption coefficient of light and surface recombination velocity. Here we propose a simple method by which one can obtain L 0 , D and τ separately from measured phase shift of short circuit photo current at some modulation frequency ω and at two different wavelengths of incident light. It is suggested that the above procedure is particularly suitable for inferring the temperature dependence of these parameters. (author). 5 refs

Temperature-dependent photoluminescence from CdS/Si nanoheterojunctions

Energy Technology Data Exchange (ETDEWEB)

Song, Yue Li; Li, Yong; Ji, Peng Fei; Zhou, Feng Qun; Sun, Xiao Jun; Yuan, Shu Qing; Wan, Ming Li [Pingdingshan University, Department of Physics, Solar New Energy Research Center, Pingdingshan (China); Ling, Hong [North China University of Water Resources and Electric Power, Department of Mathematics and Information Science, Zhengzhou (China)

2016-12-15

CdS/Si nanoheterojunctions have been fabricated by growing nanocrystal CdS (nc-CdS) on the silicon nanoporous pillar array (Si-NPA) through using a chemical bath deposition method. The nanoheterojunctions have been constructed by three layers: the upper layer being a nc-CdS thin films, the intermediate layer being the interface region including nc-CdS and nanocrystal silicon (nc-Si), and the bottom layer being nc-Si layer grown on sc-Si substrate. The room temperature and temperature-dependent photoluminescence (PL) have been measured and analyzed to provide some useful information of defect states. Utilizing the Gauss-Newton fitting method, five emission peaks from the temperature-dependent PL spectra can be determined. From the high energy to low energy, these five peaks are ascribed to the some luminescence centers which are formed by the oxygen-related deficiency centers in the silicon oxide layer of Si-NPA, the band gap emission of nc-CdS, the transition from the interstitial cadmium (I{sub Cd}) to the valence band, the recombination from I{sub Cd} to cadmium vacancies (V{sub Cd}), and from sulfur vacancies (V{sub s}) to the valence band, respectively. Understanding of the defect states in the CdS/Si nanoheterojunctions is very meaningful for the performance of devices based on CdS/Si nanoheterojunctions. (orig.)

Temperature dependence of collapse of quantized hall resistance

International Nuclear Information System (INIS)

Tanaka, Hiroyasu; Kawashima, Hironori; Iizuka, Hisamitsu; Fukuda, Hideaki; Kawaji, Shinji

2006-01-01

Similarity is observed in the deviation of Hall resistance from the quantized value with the increase in the source-drain current I SD in our butterfly-type Hall bars and in the Hall bars used by Jeanneret et al., while changes in the diagonal resistivity ρ xx with I SD are significantly different between these Hall bars. The temperature dependence of the critical Hall electric field F cr (T) for the collapse of R H (4) measured in these Hall bars is approximated using F cr (T) = F cr (0)(1 - (T/T cr ) 2 ). Here, the critical Hall electric field at zero temperature depends on the magnetic field B as F cr (0) ∝ B 3/2 . Theoretical considerations are given on F cr (T) on the basis of a temperature-dependent mobility edge model and a schema of temperature-dependent inter-Landau level tunneling probability arising from the Fermi distribution function. The former does not fit in with the I SD dependence of activation energy in ρ xx . (author)

Determination of thicknesses and temperatures of crystalline silicon wafers from optical measurements in the far infrared region

Science.gov (United States)

Franta, Daniel; Franta, Pavel; Vohánka, Jiří; Čermák, Martin; Ohlídal, Ivan

2018-05-01

Optical measurements of transmittance in the far infrared region performed on crystalline silicon wafers exhibit partially coherent interference effects appropriate for the determination of thicknesses of the wafers. The knowledge of accurate spectral and temperature dependencies of the optical constants of crystalline silicon in this spectral region is crucial for the determination of its thickness and vice versa. The recently published temperature dependent dispersion model of crystalline silicon is suitable for this purpose. Because the linear thermal expansion of crystalline silicon is known, the temperatures of the wafers can be determined with high precision from the evolution of the interference patterns at elevated temperatures.

Time dependence of magnetization of high temperature superconductors

International Nuclear Information System (INIS)

Larkin, A.I.; Geshkenbein, V.B.

1988-10-01

Magnetization of high T c superconductors logarithmically decreases with time. There is a maximum in the temperature dependence of the coefficient at this logarithm. If one assumes that there do exist two kinds of pinning centers, then this dependence can be described in the Anderson theory of thermal creeps of Abrikosov's vortices. The temperature dependence of the critical current is also discussed. (author). 23 refs

Temperature dependence of contact resistance at metal/MWNT interface

Energy Technology Data Exchange (ETDEWEB)

Lee, Sang-Eui; Moon, Kyoung-Seok; Sohn, Yoonchul, E-mail: yoonchul.son@samsung.com [Materials Research Center, Samsung Advanced Institute of Technology, Samsung Electronics, Suwon 443-803 (Korea, Republic of)

2016-07-11

Although contact resistance of carbon nanotube (CNT) is one of the most important factors for practical application of electronic devices, a study regarding temperature dependence on contact resistance of CNTs with metal electrodes has not been found. Here, we report an investigation of contact resistance at multiwalled nanotube (MWNT)/Ag interface as a function of temperature, using MWNT/polydimethylsiloxane (PDMS) composite. Electrical resistance of MWNT/PDMS composite revealed negative temperature coefficient (NTC). Excluding the contact resistance with Ag electrode, the NTC effect became less pronounced, showing lower intrinsic resistivity with the activation energy of 0.019 eV. Activation energy of the contact resistance of MWNT/Ag interface was determined to be 0.04 eV, two times larger than that of MWNT-MWNT network. The increase in the thermal fluctuation assisted electron tunneling is attributed to conductivity enhancement at both MWNT/MWNT and MWNT/Ag interfaces with increasing temperature.

Physical Attractiveness, Age, and Sex as Determinants of Reactions to Resumes.

Science.gov (United States)

Quereshi, M. Y.; Kay, Janet P.

1986-01-01

Physical attractiveness, age, and sex were manipulated to determine their effect on the evaluation of 54 hypothetical applicants' resumes for three different jobs by 60 Master's in Business Administration students. Physical attractiveness favorably influenced the suitability ratings for all jobs; raters' sex and age were not significant but…

Temperature dependence of HU values for various water equivalent phantom materials

International Nuclear Information System (INIS)

Homolka, P.; Nowotny, R.; Gahleitner, A.

2002-01-01

The temperature dependence of water equivalent phantom materials used in radiotherapy and diagnostic imaging has been investigated. Samples of phantom materials based on epoxy resin, polyethylene, a polystyrene-polypropylene mixture and commercially available phantom materials (Solid Water TM , Gammex RMI and Plastic Water TM , Nuclear Associates) were scanned at temperatures from 15 to 40 deg. C and HU values determined. At a reference temperature of 20 deg. C materials optimized for CT applications give HU values close to zero while the commercial materials show an offset of 119.77 HU (Plastic Water) and 27.69 HU (Solid Water). Temperature dependence was lowest for epoxy-based materials (EPX-W: -0.23 HU deg. C -1 ; Solid Water: -0.25 HU deg. C -1 ) and highest for a polyethylene-based material (X0: -0.72 HU deg. C -1 ). A material based on a mixture of polystyrene and polypropylene (PSPP1: -0.27 HU deg. C -1 ) is comparable to epoxy-based materials and water (-0.29 HU deg. C -1 ). (author)

The sex and sex determination in Pyropia haitanensis (Bangiales, Rhodophyta).

Science.gov (United States)

Zhang, Yuan; Yan, Xing-hong; Aruga, Yusho

2013-01-01

Pyropia haitanensis has a biphasic life cycle with macroscopic gametophytic blade (n) and microscopic filamentous conchocelis (2n) phase. Its gametophytic blades have long been believed to be mainly dioecious. However, when crossing the red mutant (R, ♀) with the wild type (W, ♂), the parental colors were segregated in F1 blades, of which 96.1% were linearly sectored with 2-4 color sectors. When color sectors were excised from the color-sectored blades and cultured singly, 99.7% of the color sectors appeared to be unisexual with an equal sex ratio. Although the sex of color sector did not genetically link with its color, the boundaries of both sex and color sectors coincided precisely. About 87.9% of the examined color-sectored blades were monoecious and the percentage increased with the number of color sectors of a blade. The gametophytic blades from each conchocelis strain produced by parthenogenesis of the excised color sectors were unisexual and unicolor, showing the same sex and color as their original sectors. These results indicate that most of the sexually reproduced Py. haitanensis blades are monoecious, and their sex is controlled by segregation of a pair of alleles during meiosis of conchospore, forming a sex-sectored tetrad. During the subsequent development of blades, one or two lower cell(s) of the tetrad contribute mainly to rhizoid formation, and rarely show their sexual phenotype, leading to reduced frequency of full sex phenotype of the meiotic blades. Moreover, the aberrant segregations of sex genes or color genes in a few of F1 blades were probably due to gene conversions, but there was no sex transfer in Py. haitanensis.

Spatio-temporal variation in the incubation duration and sex ratio of hawksbill hatchlings: implication for future management.

Science.gov (United States)

dei Marcovaldi, Maria A G; Santos, Armando J B; Santos, Alexsandro S; Soares, Luciano S; Lopez, Gustave G; Godfrey, Matthew H; López-Mendilaharsu, Milagros; Fuentes, Mariana M P B

2014-08-01

Climate change poses a unique threat to species with temperature dependent sex determination (TSD), such as marine turtles, where increases in temperature can result in extreme sex ratio biases. Knowledge of the primary sex ratio of populations with TSD is key for providing a baseline to inform management strategies and to accurately predict how future climate changes may affect turtle populations. However, there is a lack of robust data on offspring sex ratio at appropriate temporal and spatial scales to inform management decisions. To address this, we estimate the primary sex ratio of hawksbill hatchlings, Eretmochelys imbricata, from incubation duration of 5514 in situ nests from 10 nesting beaches from two regions in Brazil over the last 27 years. A strong female bias was estimated in all beaches, with 96% and 89% average female sex ratios produced in Bahia (BA) and Rio Grande do Norte (RN). Both inter-annual (BA, 88 to 99%; RN, 75 to 96% female) and inter-beach (BA, 92% to 97%; RN, 81% to 92% female) variability in mean offspring sex ratio was observed. These findings will guide management decisions in Brazil and provide further evidence of highly female-skew sex ratios in hawksbill turtles. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of COMT Val158Met polymorphism on emotional decision-making: A sex-dependent relationship?

Science.gov (United States)

Costa, Danielle de Souza; Bechara, Antoine; de Paula, Jonas Jardim; Romano-Silva, Marco Aurélio; Correa, Humberto; Lage, Guilherme Menezes; Miranda, Débora Marques de; Malloy-Diniz, Leandro Fernandes

2016-12-30

The biological underpinnings of sex-related differences in decision-making are still under-explored. The COMT gene is related to sexual dimorphism and with different choices made under uncertainty, albeit no study has specifically investigated a moderation effect of sex on the association between the COMT gene and the performance on decision-making paradigms. In this study, we investigated the influence of the COMT Val 158 Met polymorphism on Iowa Gambling Task (IGT) performance depending on sex in a healthy adult sample. Participants were 192 healthy adults (84 men and 108 women). The first 40 choices in the IGT were considered decisions under ambiguity and the last 60 choices decisions under risk. To test our moderation hypothesis we used a separate regressions approach. The results revealed a sex-dependent effect of COMT Va l 158 Met polymorphism on decision-making as measured by the IGT. Val/Val women showed the best performance in the last trials of the IGT. Therefore, the COMT Val 158 Met polymorphism may be considered a genetic marker underlying sex differences in decision-making. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Evaluation of temperature dependent neutron resonance integrals

International Nuclear Information System (INIS)

Menon, S.V.G.; Sahni, D.C.

1975-01-01

The Fourier transform method is extended for evaluating temperature dependent resonance integrals and Doppler coefficients. With the temperature dependent cross-sections, the slowing-down equation is transformed into a Fredholm integral equation of second kind. A method of solution is presented using the familiar Gauss-Hermite quadrature formulae. As a byproduct of the above technique, a fast and accurate method for computing the resonance integral J-function is given. (orig.) [de

Sex determination in Madagascar geckos of the genus Paroedura (Squamata: Gekkonidae): are differentiated sex chromosomes indeed so evolutionary stable?

Czech Academy of Sciences Publication Activity Database

Koubová, M.; Johnson Pokorná, Martina; Rovatsos, M.; Farkačová, K.; Altmanová, M.; Kratochvíl, L.

2014-01-01

Roč. 22, č. 4 (2014), s. 441-452 ISSN 0967-3849 R&D Projects: GA ČR GAP506/10/0718 Institutional support: RVO:67985904 Keywords : sex chromosomes * heterochromatin * reptiles * sex determination * FISH * ITSs Subject RIV: EG - Zoology Impact factor: 2.478, year: 2014

Different male versus female breeding periodicity helps mitigate offspring sex ratio skews in sea turtles

Directory of Open Access Journals (Sweden)

Graeme Clive Hays

2014-09-01

Full Text Available The implications of climate change for global biodiversity may be profound with those species with little capacity for adaptation being thought to be particularly vulnerable to warming. A classic case of groups for concern are those animals exhibiting temperature-dependent sex-determination (TSD, such as sea turtles, where climate warming may produce single sex populations and hence extinction. We show that, globally, female biased hatchling sex ratios dominate sea turtle populations (exceeding 3:1 in >50% records, which, at-a-glance, reiterates concerns for extinction. However, we also demonstrate that more frequent breeding by males, empirically shown by satellite tracking 23 individuals and supported by a generalized bio-energetic life history model, generates more balanced operational sex ratios (OSRs. Hence, concerns of increasingly skewed hatchling sex ratios and reduced population viability are less acute than previously thought for sea turtles. In fact, in some scenarios skewed hatchling sex ratios in groups with TSD may be adaptive to ensure optimum OSRs.

Abortion and sex determination: conflicting messages in information materials in a District of Rajasthan, India.

Science.gov (United States)

Nidadavolu, Vijaya; Bracken, Hillary

2006-05-01

Public information campaigns are an integral component of reproductive health programmes, including on abortion. In India, where sex selective abortion is increasing, public information is being disseminated on the illegality of sex determination. This paper presents findings from a study undertaken in 2003 in one district in Rajasthan to analyse the content of information materials on abortion and sex determination and people's perceptions of them. Most of the informational material about abortion was produced by one abortion service provider, but none by the public or private sector. The public sector had produced materials on the illegality of sex determination, some of which failed to distinguish between sex selection and other reasons for abortion. In the absence of knowledge of the legal status of abortion, the negative messages and strong language of these materials may have contributed to the perception that abortion is illegal in India. Future materials should address abortion and sex determination, including the legal status of abortion, availability of providers and social norms that shape decision-making. Married and unmarried women should be addressed and the participation of family members acknowledged, while supporting independent decisions by women. Sex determination should also be addressed, and the conditions under which a woman can and cannot seek an abortion clarified, using media and materials accessible to low-literate audiences. Based on what we learned in this research, a pictorial booklet and educator's manual were produced, covering both abortion and sex determination, and are being distributed in India.

Temperature dependence of bulk respiration of crop stands. Measurement and model fitting

International Nuclear Information System (INIS)

Tani, Takashi; Arai, Ryuji; Tako, Yasuhiro

2007-01-01

The objective of the present study was to examine whether the temperature dependence of respiration at a crop-stand scale could be directly represented by an Arrhenius function that was widely used for representing the temperature dependence of leaf respiration. We determined temperature dependences of bulk respiration of monospecific stands of rice and soybean within a range of the air temperature from 15 to 30degC using large closed chambers. Measured responses of respiration rates of the two stands were well fitted by the Arrhenius function (R 2 =0.99). In the existing model to assess the local radiological impact of the anthropogenic carbon-14, effects of the physical environmental factors on photosynthesis and respiration of crop stands are not taken into account for the calculation of the net amount of carbon per cultivation area in crops at harvest which is the crucial parameter for the estimation of the activity concentration of carbon-14 in crops. Our result indicates that the Arrhenius function is useful for incorporating the effect of the temperature on respiration of crop stands into the model which is expected to contribute to a more realistic estimate of the activity concentration of carbon-14 in crops. (author)

Sex determination of a Tunisian population by CT scan analysis of the skull.

Science.gov (United States)

Zaafrane, Malek; Ben Khelil, Mehdi; Naccache, Ines; Ezzedine, Ekbel; Savall, Frédéric; Telmon, Norbert; Mnif, Najla; Hamdoun, Moncef

2018-05-01

It is widely accepted that the estimation of biological attributes in the human skeleton is more accurate when population-specific standards are applied. With the shortage of such data for contemporary North African populations, it is duly required to establish population-specific standards. We present here the first craniometric standards for sex determination of a contemporary Tunisian population. The aim of this study was to analyze the correlation between sex and metric parameters of the skull in this population using CT scan analysis and to generate proper reliable standards for sex determination of a complete or fragmented skull. The study sample comprised cranial multislice computed tomography scans of 510 individuals equally distributed by sex. ASIR TM software in a General Electric TM workstation was used to position 37 landmarks along the volume-rendered images and the multiplanar slices, defining 27 inter-landmark distances. Frontal and parietal bone thickness was also measured for each case. The data were analyzed using basic descriptive statistics and logistic regression with cross-validation of classification results. All of the measurements were sexually dimorphic with male values being higher than female values. A nine-variable model achieved the maximum classification accuracy of 90% with -2.9% sex bias and a six-variable model yielded 85.9% sexing accuracy with -0.97% sex bias. We conclude that the skull is highly dimorphic and represents a reliable bone for sex determination in contemporary Tunisian individuals.

Fgf9 and Wnt4 act as antagonistic signals to regulate mammalian sex determination.

Directory of Open Access Journals (Sweden)

Yuna Kim

2006-06-01

Full Text Available The genes encoding members of the wingless-related MMTV integration site (WNT and fibroblast growth factor (FGF families coordinate growth, morphogenesis, and differentiation in many fields of cells during development. In the mouse, Fgf9 and Wnt4 are expressed in gonads of both sexes prior to sex determination. Loss of Fgf9 leads to XY sex reversal, whereas loss of Wnt4 results in partial testis development in XX gonads. However, the relationship between these signals and the male sex-determining gene, Sry, was unknown. We show through gain- and loss-of-function experiments that fibroblast growth factor 9 (FGF9 and WNT4 act as opposing signals to regulate sex determination. In the mouse XY gonad, Sry normally initiates a feed-forward loop between Sox9 and Fgf9, which up-regulates Fgf9 and represses Wnt4 to establish the testis pathway. Surprisingly, loss of Wnt4 in XX gonads is sufficient to up-regulate Fgf9 and Sox9 in the absence of Sry. These data suggest that the fate of the gonad is controlled by antagonism between Fgf9 and Wnt4. The role of the male sex-determining switch--Sry in the case of mammals--is to tip the balance between these underlying patterning signals. In principle, sex determination in other vertebrates may operate through any switch that introduces an imbalance between these two signaling pathways.

The effect of utilising age and sex dependent factors for calculating detriment from medical irradiation

International Nuclear Information System (INIS)

Mettler, F.A.; Davis, M.; Moseley, R.D.; Kelsey, C.A.

1986-01-01

Proposals have been made for a quantity that can be used to estimate possible detriment from medical radiology better than the ICRP's collective effective dose equivalent. One such approach utilises age and sex dependent 'weighting' factors. The magnitude of the effect obtained by utilising such factors when applied to an actual population has not been previously assessed. When age and sex dependent weighting factors are applied to diagnostic medical radiology for all hospital examinations conducted in the United States in 1980, estimates of detriment are reduced by one-third. (author)

Temperature dependent lattice constant of InSb above room temperature

Science.gov (United States)

Breivik, Magnus; Nilsen, Tron Arne; Fimland, Bjørn-Ove

2013-10-01

Using temperature dependent X-ray diffraction on two InSb single crystalline substrates, the bulk lattice constant of InSb was determined between 32 and 325 °C. A polynomial function was fitted to the data: a(T)=6.4791+3.28×10-5×T+1.02×10-8×T2 Å (T in °C), which gives slightly higher values than previously published (which go up to 62 °C). From the fit, the thermal expansion of InSb was calculated to be α(T)=5.062×10-6+3.15×10-9×T K-1 (T in °C). We found that the thermal expansion coefficient is higher than previously published values above 100 °C (more than 10% higher at 325 °C).

Structure–function analysis of mouse Sry reveals dual essential roles of the C-terminal polyglutamine tract in sex determination

Science.gov (United States)

Zhao, Liang; Ng, Ee Ting; Davidson, Tara-Lynne; Longmuss, Enya; Urschitz, Johann; Elston, Marlee; Moisyadi, Stefan; Bowles, Josephine; Koopman, Peter

2014-01-01

The mammalian sex-determining factor SRY comprises a conserved high-mobility group (HMG) box DNA-binding domain and poorly conserved regions outside the HMG box. Mouse Sry is unusual in that it includes a C-terminal polyglutamine (polyQ) tract that is absent in nonrodent SRY proteins, and yet, paradoxically, is essential for male sex determination. To dissect the molecular functions of this domain, we generated a series of Sry mutants, and studied their biochemical properties in cell lines and transgenic mouse embryos. Sry protein lacking the polyQ domain was unstable, due to proteasomal degradation. Replacing this domain with irrelevant sequences stabilized the protein but failed to restore Sry’s ability to up-regulate its key target gene SRY-box 9 (Sox9) and its sex-determining function in vivo. These functions were restored only when a VP16 transactivation domain was substituted. We conclude that the polyQ domain has important roles in protein stabilization and transcriptional activation, both of which are essential for male sex determination in mice. Our data disprove the hypothesis that the conserved HMG box domain is the only functional domain of Sry, and highlight an evolutionary paradox whereby mouse Sry has evolved a novel bifunctional module to activate Sox9 directly, whereas SRY proteins in other taxa, including humans, seem to lack this ability, presumably making them dependent on partner proteins(s) to provide this function. PMID:25074915

Structure-function analysis of mouse Sry reveals dual essential roles of the C-terminal polyglutamine tract in sex determination.

Science.gov (United States)

Zhao, Liang; Ng, Ee Ting; Davidson, Tara-Lynne; Longmuss, Enya; Urschitz, Johann; Elston, Marlee; Moisyadi, Stefan; Bowles, Josephine; Koopman, Peter

2014-08-12

The mammalian sex-determining factor SRY comprises a conserved high-mobility group (HMG) box DNA-binding domain and poorly conserved regions outside the HMG box. Mouse Sry is unusual in that it includes a C-terminal polyglutamine (polyQ) tract that is absent in nonrodent SRY proteins, and yet, paradoxically, is essential for male sex determination. To dissect the molecular functions of this domain, we generated a series of Sry mutants, and studied their biochemical properties in cell lines and transgenic mouse embryos. Sry protein lacking the polyQ domain was unstable, due to proteasomal degradation. Replacing this domain with irrelevant sequences stabilized the protein but failed to restore Sry's ability to up-regulate its key target gene SRY-box 9 (Sox9) and its sex-determining function in vivo. These functions were restored only when a VP16 transactivation domain was substituted. We conclude that the polyQ domain has important roles in protein stabilization and transcriptional activation, both of which are essential for male sex determination in mice. Our data disprove the hypothesis that the conserved HMG box domain is the only functional domain of Sry, and highlight an evolutionary paradox whereby mouse Sry has evolved a novel bifunctional module to activate Sox9 directly, whereas SRY proteins in other taxa, including humans, seem to lack this ability, presumably making them dependent on partner proteins(s) to provide this function.

Temperature dependence of exchange bias in (NiFe/IrMn)n multilayer films studied through static and dynamic techniques

Science.gov (United States)

Adams, Daniel J.; Khanal, Shankar; Khan, Mohammad Asif; Maksymov, Artur; Spinu, Leonard

2018-05-01

The in-plane temperature dependence of exchange bias was studied through both dc magnetometry and ferromagnetic resonance spectroscopy in a series of [NiFe/IrMn]n multilayer films, where n is the number of layer repetitions. Major hysteresis loops were recorded in the temperature range of 300 K to 2 K to reveal the effect of temperature on the exchange bias in the static regime while temperature-dependent continuous-wave ferromagnetic resonance for frequencies from 3 to 16 GHz was used to determine the exchange bias dynamically. Strong divergence between the values of exchange bias determined using the two different types of measurements as well as a peak in temperature dependence of the resonance linewidth were observed. These results are explained in terms of the slow-relaxer mechanism.

Patterns in new dimensionless quantities containing melting temperature, and their dependence on pressure

Directory of Open Access Journals (Sweden)

U. WALZER

1980-06-01

Full Text Available The relationships existing between melting temperature and other
macroscopic physical quantities are investigated. A new dimensionless
quantity Q(1 not containing the Grtineisen parameter proves to be suited for serving in future studies as a tool for the determination of the melting temperature in the outer core of the Earth. The pressure dependence of more general dimensionless quantities Q„ is determined analytically and, for the chemical elements, numerically, too. The patterns of various interesting dimensionless quantities are shown in the Periodic Table and compared.

Glass transition in thaumatin crystals revealed through temperature-dependent radiation-sensitivity measurements

Energy Technology Data Exchange (ETDEWEB)

Warkentin, Matthew, E-mail: maw64@cornell.edu; Thorne, Robert E. [Physics Department, Cornell University, Ithaca, New York (United States)

2010-10-01

Radiation damage to protein crystals exhibits two regimes of temperature-activated behavior between T = 300 and 100 K, with a crossover at the protein glass transition near 200 K. These results have implications for mechanistic studies of proteins and for structure determination when cooling to T = 100 K creates excessive disorder. The temperature-dependence of radiation damage to thaumatin crystals between T = 300 and 100 K is reported. The amount of damage for a given dose decreases sharply as the temperature decreases from 300 to 220 K and then decreases more gradually on further cooling below the protein-solvent glass transition. Two regimes of temperature-activated behavior were observed. At temperatures above ∼200 K the activation energy of 18.0 kJ mol{sup −1} indicates that radiation damage is dominated by diffusive motions in the protein and solvent. At temperatures below ∼200 K the activation energy is only 1.00 kJ mol{sup −1}, which is of the order of the thermal energy. Similar activation energies describe the temperature-dependence of radiation damage to a variety of solvent-free small-molecule organic crystals over the temperature range T = 300–80 K. It is suggested that radiation damage in this regime is vibrationally assisted and that the freezing-out of amino-acid scale vibrations contributes to the very weak temperature-dependence of radiation damage below ∼80 K. Analysis using the radiation-damage model of Blake and Phillips [Blake & Phillips (1962 ▶), Biological Effects of Ionizing Radiation at the Molecular Level, pp. 183–191] indicates that large-scale conformational and molecular motions are frozen out below T = 200 K but become increasingly prevalent and make an increasing contribution to damage at higher temperatures. Possible alternative mechanisms for radiation damage involving the formation of hydrogen-gas bubbles are discussed and discounted. These results have implications for mechanistic studies of proteins and for

Bombyx mori histone methyltransferase BmAsh2 is essential for silkworm piRNA-mediated sex determination.

Science.gov (United States)

Li, Zhiqian; You, Lang; Yan, Dong; James, Anthony A; Huang, Yongping; Tan, Anjiang

2018-02-01

Sex determination is a hierarchically-regulated process with high diversity in different organisms including insects. The W chromosome-derived Fem piRNA has been identified as the primary sex determination factor in the lepidopteran insect, Bombyx mori, revealing a distinctive piRNA-mediated sex determination pathway. However, the comprehensive mechanism of silkworm sex determination is still poorly understood. We show here that the silkworm PIWI protein BmSiwi, but not BmAgo3, is essential for silkworm sex determination. CRISPR/Cas9-mediated depletion of BmSiwi results in developmental arrest in oogenesis and partial female sexual reversal, while BmAgo3 depletion only affects oogenesis. We identify three histone methyltransferases (HMTs) that are significantly down-regulated in BmSiwi mutant moths. Disruption one of these, BmAsh2, causes dysregulation of piRNAs and transposable elements (TEs), supporting a role for it in the piRNA signaling pathway. More importantly, we find that BmAsh2 mutagenesis results in oogenesis arrest and partial female-to-male sexual reversal as well as dysregulation of the sex determination genes, Bmdsx and BmMasc. Mutagenesis of other two HMTs, BmSETD2 and BmEggless, does not affect piRNA-mediated sex determination. Histological analysis and immunoprecipitation results support a functional interaction between the BmAsh2 and BmSiwi proteins. Our data provide the first evidence that the HMT, BmAsh2, plays key roles in silkworm piRNA-mediated sex determination.

Bombyx mori histone methyltransferase BmAsh2 is essential for silkworm piRNA-mediated sex determination.

Directory of Open Access Journals (Sweden)

Zhiqian Li

2018-02-01

Full Text Available Sex determination is a hierarchically-regulated process with high diversity in different organisms including insects. The W chromosome-derived Fem piRNA has been identified as the primary sex determination factor in the lepidopteran insect, Bombyx mori, revealing a distinctive piRNA-mediated sex determination pathway. However, the comprehensive mechanism of silkworm sex determination is still poorly understood. We show here that the silkworm PIWI protein BmSiwi, but not BmAgo3, is essential for silkworm sex determination. CRISPR/Cas9-mediated depletion of BmSiwi results in developmental arrest in oogenesis and partial female sexual reversal, while BmAgo3 depletion only affects oogenesis. We identify three histone methyltransferases (HMTs that are significantly down-regulated in BmSiwi mutant moths. Disruption one of these, BmAsh2, causes dysregulation of piRNAs and transposable elements (TEs, supporting a role for it in the piRNA signaling pathway. More importantly, we find that BmAsh2 mutagenesis results in oogenesis arrest and partial female-to-male sexual reversal as well as dysregulation of the sex determination genes, Bmdsx and BmMasc. Mutagenesis of other two HMTs, BmSETD2 and BmEggless, does not affect piRNA-mediated sex determination. Histological analysis and immunoprecipitation results support a functional interaction between the BmAsh2 and BmSiwi proteins. Our data provide the first evidence that the HMT, BmAsh2, plays key roles in silkworm piRNA-mediated sex determination.

Room-temperature and temperature-dependent QSRR modelling for predicting the nitrate radical reaction rate constants of organic chemicals using ensemble learning methods.

Science.gov (United States)

Gupta, S; Basant, N; Mohan, D; Singh, K P

2016-07-01

Experimental determinations of the rate constants of the reaction of NO3 with a large number of organic chemicals are tedious, and time and resource intensive; and the development of computational methods has widely been advocated. In this study, we have developed room-temperature (298 K) and temperature-dependent quantitative structure-reactivity relationship (QSRR) models based on the ensemble learning approaches (decision tree forest (DTF) and decision treeboost (DTB)) for predicting the rate constant of the reaction of NO3 radicals with diverse organic chemicals, under OECD guidelines. Predictive powers of the developed models were established in terms of statistical coefficients. In the test phase, the QSRR models yielded a correlation (r(2)) of >0.94 between experimental and predicted rate constants. The applicability domains of the constructed models were determined. An attempt has been made to provide the mechanistic interpretation of the selected features for QSRR development. The proposed QSRR models outperformed the previous reports, and the temperature-dependent models offered a much wider applicability domain. This is the first report presenting a temperature-dependent QSRR model for predicting the nitrate radical reaction rate constant at different temperatures. The proposed models can be useful tools in predicting the reactivities of chemicals towards NO3 radicals in the atmosphere, hence, their persistence and exposure risk assessment.

Temperature dependence of grain boundary free energy and elastic constants

International Nuclear Information System (INIS)

Foiles, Stephen M.

2010-01-01

This work explores the suggestion that the temperature dependence of the grain boundary free energy can be estimated from the temperature dependence of the elastic constants. The temperature-dependent elastic constants and free energy of a symmetric Σ79 tilt boundary are computed for an embedded atom method model of Ni. The grain boundary free energy scales with the product of the shear modulus times the lattice constant for temperatures up to about 0.75 the melting temperature.

Sex determination using cheiloscopy and mandibular canine index as a tool in forensic dentistry

Directory of Open Access Journals (Sweden)

B Bhagyashree

2018-01-01

Full Text Available Identification of a person′s individuality and sex determination are important for legal as well as identification purposes. The aim of the present study was to check the reliability of cheiloscopy and mandibular canine index (MCI in the determination of sex in an individual. The aim of this study is to analyze different lip patterns reproduced by the natural dye (vermilion and lysochrome (Sudan Black II dyes and to compare the MCI in males and females for the determination of sex and to check the reliability of cheiloscopy and MCI for the same. Latent lip prints were developed using natural dye (vermilion and lysochrome (Sudan Black II dyes and their patterns categorized according to Tsuchihashi′s classification. MCI were calculated. Analysis of the two was performed. According to discriminant functional analysis, percentage accuracy for cheiloscopy in the determination of sex was found to be 55% while for MCI, the same value was 85%. Natural dye (vermilion was found as an efficient dye compared to lysochrome (Sudan Black II dyes for the development of latent lip prints. Both the dyes showed Type I lip print pattern to be common in males and females. Furthermore, all the parameters in MCI were found to be significant in the determination of sex in an individual. The results of the present study revealed MCI to be more reliable in the determination of sex than cheiloscopy.

Observing the temperature dependent transition of the GP2 peptide using terahertz spectroscopy.

Directory of Open Access Journals (Sweden)

Yiwen Sun

Full Text Available The GP2 peptide is derived from the Human Epidermal growth factor Receptor 2 (HER2/nue, a marker protein for breast cancer present in saliva. In this paper we study the temperature dependent behavior of hydrated GP2 at terahertz frequencies and find that the peptide undergoes a dynamic transition between 200 and 220 K. By fitting suitable molecular models to the frequency response we determine the molecular processes involved above and below the transition temperature (T(D. In particular, we show that below T(D the dynamic transition is dominated by a simple harmonic vibration with a slow and temperature dependent relaxation time constant and that above T(D, the dynamic behavior is governed by two oscillators, one of which has a fast and temperature independent relaxation time constant and the other of which is a heavily damped oscillator with a slow and temperature dependent time constant. Furthermore a red shifting of the characteristic frequency of the damped oscillator was observed, confirming the presence of a non-harmonic vibration potential. Our measurements and modeling of GP2 highlight the unique capabilities of THz spectroscopy for protein characterization.

Temperature-dependent piezoresistivity in an MWCNT/epoxy nanocomposite temperature sensor with ultrahigh performance

International Nuclear Information System (INIS)

Alamusi; Li, Yuan; Hu, Ning; Wu, Liangke; Liu, Yaolu; Ning, Huiming; Li, Jinhua; Surina; Yuan, Weifeng; Chang, Christiana; Atobe, Satoshi; Fukunaga, Hisao

2013-01-01

A temperature sensor was fabricated from a polymer nanocomposite with multi-walled carbon nanotube (MWCNT) as nanofiller (i.e., MWCNT/epoxy). The electrical resistance and temperature coefficient of resistance (TCR) of the temperature sensor were characterized experimentally. The effects of temperature (within the range 333–373 K) and MWCNT content (within the range 1–5 wt%) were investigated thoroughly. It was found that the resistance increases with increasing temperature and decreasing MWCNT content. However, the resistance change ratio related to the TCR increases with increasing temperature and MWCNT content. The highest value of TCR (0.021 K −1 ), which was observed in the case of 5 wt% MWCNT, is much higher than those of traditional metals and MWCNT-based temperature sensors. Moreover, the corresponding numerical simulation—conducted to explain the above temperature-dependent piezoresistivity of the nanocomposite temperature sensor—indicated the key role of a temperature-dependent tunneling effect. (paper)

Temperature dependent quasiparticle renormalization in nickel metal

Energy Technology Data Exchange (ETDEWEB)

Ovsyannikov, Ruslan; Sanchez-Barriga, Jaime; Fink, Joerg; Duerr, Hermann A. [Helmholtz Zentrum Berlin (Germany). BESSY II

2009-07-01

One of the fundamental consequences of electron correlation effects is that the bare particles in solids become 'dressed', i.e. they acquire an increased effective mass and a lifetime. We studied the spin dependent quasiparticle band structure of Ni(111) with high resolution angle resolved photoemission spectroscopy. At low temperatures (50 K) a renormalization of quasiparticle energy and lifetime indicative of electron-phonon coupling is observed in agreement with literature. With increasing temperature we observe a decreasing quasiparticle lifetime at the Fermi level for all probed minority spin bands as expected from electron phonon coupling. Surprisingly the majority spin states behave differently. We actually observe a slightly increased lifetime at room temperature. The corresponding increase in Fermi velocity points to a temperature dependent reduction of the majority spin quasiparticle renormalization.

Prevalence and determinants of online-sex use in the German population.

Directory of Open Access Journals (Sweden)

Manfred E Beutel

Full Text Available The unlimited access to sexual features in the World Wide Web has raised concerns about excessive and problematic online-sex use. However, little is known about antecedents of internet-sex use of different intensity. Based on a representative German sample of 2,522 participants between the ages of 14 and 97 years, the aims of the present study were (1 to determine the prevalence rates of online-sex users with the short version (ISSTGSV of the Internet Sex Screening Test and (2 to associate online-sex use with anxious vs. avoidant partner attachment patterns and "Big Five" personality traits as potential antecedents.The ISST is a brief, one-dimensional and reliable measure of online-sex activities (rtt = .69. Overall, 14.7% of respondents reported occasional and 4.2% intensive online-sex use. In multivariate analysis, online-sex use was significantly positively associated with male sex, younger age, unemployment and an anxious partner attachment pattern and negatively with conscientiousness and agreeableness.Arousal and satisfaction by virtual enactment of sexual phantasies may be attractive for anxiously attached persons who find it difficult to commit to a real life relationship due to fear of rejection or low self-esteem. More knowledge about the individual antecedents of intensive online-sex use may also be helpful for the development of consultation and treatment strategies for excessive and addictive online-sex use.

Prevalence and determinants of online-sex use in the German population.

Science.gov (United States)

Beutel, Manfred E; Giralt, Sebastian; Wölfling, Klaus; Stöbel-Richter, Yve; Subic-Wrana, Claudia; Reiner, Iris; Tibubos, Ana Nanette; Brähler, Elmar

2017-01-01

The unlimited access to sexual features in the World Wide Web has raised concerns about excessive and problematic online-sex use. However, little is known about antecedents of internet-sex use of different intensity. Based on a representative German sample of 2,522 participants between the ages of 14 and 97 years, the aims of the present study were (1) to determine the prevalence rates of online-sex users with the short version (ISSTGSV) of the Internet Sex Screening Test and (2) to associate online-sex use with anxious vs. avoidant partner attachment patterns and "Big Five" personality traits as potential antecedents. The ISST is a brief, one-dimensional and reliable measure of online-sex activities (rtt = .69). Overall, 14.7% of respondents reported occasional and 4.2% intensive online-sex use. In multivariate analysis, online-sex use was significantly positively associated with male sex, younger age, unemployment and an anxious partner attachment pattern and negatively with conscientiousness and agreeableness. Arousal and satisfaction by virtual enactment of sexual phantasies may be attractive for anxiously attached persons who find it difficult to commit to a real life relationship due to fear of rejection or low self-esteem. More knowledge about the individual antecedents of intensive online-sex use may also be helpful for the development of consultation and treatment strategies for excessive and addictive online-sex use.

Sex differences in HIV effects on visual memory among substance-dependent individuals.

Science.gov (United States)

Keutmann, Michael K; Gonzalez, Raul; Maki, Pauline M; Rubin, Leah H; Vassileva, Jasmin; Martin, Eileen M

2017-08-01

HIV's effects on episodic memory have not been compared systematically between male and female substance-dependent individuals. We administered the Brief Visuospatial Memory Test-Revised (BVMT-R) to 280 substance-dependent HIV+ and HIV- men and women. Groups were comparable on demographic, substance use, and comorbid characteristics. There were no significant main effects of sex or HIV serostatus on BVMT-R performance, but HIV+ women performed significantly more poorly on delayed recall. This effect was most prominent among cocaine-dependent HIV+ women. Our findings are consistent with recent speculation that memory impairment may be more common among HIV+ women, particularly those with a history of cocaine dependence.

Modelled temperature-dependent excitability behaviour of a generalised human peripheral sensory nerve fibre.

Science.gov (United States)

Smit, Jacoba E; Hanekom, Tania; Hanekom, Johan J

2009-08-01

The objective of this study was to determine if a recently developed human Ranvier node model, which is based on a modified version of the Hodgkin-Huxley model, could predict the excitability behaviour in human peripheral sensory nerve fibres with diameters ranging from 5.0 to 15.0 microm. The Ranvier node model was extended to include a persistent sodium current and was incorporated into a generalised single cable nerve fibre model. Parameter temperature dependence was included. All calculations were performed in Matlab. Sensory nerve fibre excitability behaviour characteristics predicted by the new nerve fibre model at different temperatures and fibre diameters compared well with measured data. Absolute refractory periods deviated from measured data, while relative refractory periods were similar to measured data. Conduction velocities showed both fibre diameter and temperature dependence and were underestimated in fibres thinner than 12.5 microm. Calculated strength-duration time constants ranged from 128.5 to 183.0 micros at 37 degrees C over the studied nerve fibre diameter range, with chronaxie times about 30% shorter than strength-duration time constants. Chronaxie times exhibited temperature dependence, with values overestimated by a factor 5 at temperatures lower than body temperature. Possible explanations include the deviated absolute refractory period trend and inclusion of a nodal strangulation relationship.

Temperature Dependence of Short-Range Order in β-Brass

DEFF Research Database (Denmark)

Dietrich, O.W.; Als-Nielsen, Jens Aage

1967-01-01

Critical scattering of neutrons around the superlattice reflections (1, 0, 0) and (1, 1, 1) from a single crystal of beta-brass has been measured at temperatures from 2 to 25deg C above the transition temperature. The temperature dependence of the critical peak intensity, proportional to the susc......Critical scattering of neutrons around the superlattice reflections (1, 0, 0) and (1, 1, 1) from a single crystal of beta-brass has been measured at temperatures from 2 to 25deg C above the transition temperature. The temperature dependence of the critical peak intensity, proportional...

Sex ratio variation and sex determination in Urtica dioica

NARCIS (Netherlands)

Glawe, Grit Anja

2006-01-01

This thesis will first document on variation in progeny sex ratios among individual female plants of Urtica dioica at our field site in Meijendel (Chapter 2). Next, we show that there is also considerable sex ratio variation among male and female flowering shoots in 26 natural populations studied

Feedback Control of Sex Determination by Dosage Compensation Revealed through Caenorhabditis Elegans Sdc-3 Mutations

OpenAIRE

DeLong, L.; Plenefisch, J. D.; Klein, R. D.; Meyer, B. J.

1993-01-01

In Caenorhabditis elegans, sex determination and dosage compensation are coordinately controlled through a group of genes that respond to the primary sex determination signal. Here we describe a new gene, sdc-3, that also controls these processes. In contrast to previously described genes, the sex determination and dosage compensation activities of sdc-3 are separately mutable, indicating that they function independently. Paradoxically, the sdc-3 null phenotype fails to reveal the role of sdc...

The temperature dependences of electromechanical properties of PLZT ceramics

Science.gov (United States)

Czerwiec, M.; Zachariasz, R.; Ilczuk, J.

2008-02-01

The mechanical and electrical properties in lanthanum modified lead zirconate-titanate ceramics of 5/50/50 and 10/50/50 were studied by mechanical loss Q - 1, Young's modulus E, electric permittivity ɛ and tangent of dielectric loss of angle tgδ measurements. The internal friction Q - 1 and Young modulus E measured from 290 K to 600 K shows that Curie temperature TC is located at 574 K and 435 K (1st cycle of heating) respectively for ceramic samples 5/50/50 and 10/50/50. The movement of TC in second cycle of heating to lower temperature (561 K for 5/50/50 and 420 K for 10/50/50) has been observed. Together with Q - 1 and E measurements, temperature dependences of ɛ=f(T) and tgδ=f(T) were determinated in temperature range from 300 K to 730 K. The values of TC obtained during ɛ and tgδ measurements were respectively: 560 K for 5/50/50 and 419 K for 10/50/50. These temperatures are almost as high as the temperatures obtained by internal friction Q - 1 measurements in second cycle of heating. In ceramic sample 10/50/50 the additional maximum on internal friction Q - 1 curve at the temperature 316 K was observed.

A NEW HYPOTHESIS ON THE EVOLUTION OF SEX DETERMINATION IN VERTEBRATES - BIG FEMALES ZW, BIG MALES XY

NARCIS (Netherlands)

KRAAK, SBM; DELOOZE, EMA

1993-01-01

Why are there two chromosomal sex-determining mechanisms in vertebrates; ZW/ZZ, meaning female heterogamety, and XX/XY, meaning male heterogamety? We propose an evolutionary explanation. Transition from environmental sex determination to genetic sex determination can result when an allele that

(Alpha-) quenching temperature dependence in liquid scintillator

Energy Technology Data Exchange (ETDEWEB)

Soerensen, Arnd; Lozza, Valentina; Krosigk, Belina von; Zuber, Kai [Institut fuer Kern- und Teilchenphysik, TU Dresden (Germany)

2015-07-01

Liquid scintillator (LS) is an effective and promising detector material, which is and will be used by many small and large scale experiments. In order to perform correct signal identification and background suppression, a very good knowledge of LS properties is crucial. One of those is the light yield from alpha particles in liquid scintillator. This light output strongly quenched, approx. 10 times compared to that of electrons, and has been precisely studied at room temperature for various LS. Big scintillator experiments, such as SNO+ and maybe future large scale detectors, will operate at different temperatures. While a strong temperature dependence is well known for solid state scintillators, due to the different scintillation process, a quenching temperature dependence in LS is usually assumed negligible. On the other hand, inconsistencies in between measurements are often explained by potential temperature effects. This study investigates LAB based liquid scintillator with an intrinsic, dissolved alpha emitter and its behaviour with temperature change. In a small, cooled and heated setup, a stabilized read-out with two PMTs is realised. First results are presented.

Determination of magnetic characteristics of nanoparticles by low-temperature calorimetry methods

Energy Technology Data Exchange (ETDEWEB)

Ugulava, A.; Toklikishvili, Z. [Department of Physics, I.Javakhishvili Tbilisi State University,I.Chavchavadze av. 3, 0179 Tbilisi, Georgia (United States); Chkhaidze, S., E-mail: simon.chkhaidze@tsu.ge [Department of Physics, I.Javakhishvili Tbilisi State University,I.Chavchavadze av. 3, 0179 Tbilisi, Georgia (United States); Kekutia, Sh. [V. Chavchanidze Institute of Cybernetics, at the Technical State University, S. Euli str. 5, 0186 Tbilisi, Georgia (United States)

2017-05-15

At low temperatures, the heat capacity of a superparamagnetic “ideal gas” determined by magnetic degrees of freedom can greatly exceed the lattice heat capacity. It is shown that in the presence of an external magnetic field, the temperature dependence of the magnetic part of the heat capacity has two maxima. The relations between the temperature at which these maxima are achieved, the magnetic moment of the nanoparticles and the magnetic anisotropy constant have been obtained. Measuring the heat capacity maxima temperatures by low-temperature calorimetry methods and using the obtained relations, we can obtain the numerical values both of the magnetic moment of nanoparticles and the magnetic anisotropy constants.

Sex and hibernaculum temperature predict survivorship in white-nose syndrome affected little brown myotis (Myotis lucifugus)

Science.gov (United States)

Grieneisen, Laura E.; Brownlee-Bouboulis, Sarah A.; Johnson, Joseph S.; Reeder, DeeAnn M.

2015-01-01

White-nose syndrome (WNS), an emerging infectious disease caused by the novel fungus Pseudogymnoascus destructans, has devastated North American bat populations since its discovery in 2006. The little brown myotis, Myotis lucifugus, has been especially affected. The goal of this 2-year captive study was to determine the impact of hibernacula temperature and sex on WNS survivorship in little brown myotis that displayed visible fungal infection when collected from affected hibernacula. In study 1, we found that WNS-affected male bats had increased survival over females and that bats housed at a colder temperature survived longer than those housed at warmer temperatures. In study 2, we found that WNS-affected bats housed at a colder temperature fared worse than unaffected bats. Our results demonstrate that WNS mortality varies among individuals, and that colder hibernacula are more favourable for survival. They also suggest that female bats may be more negatively affected by WNS than male bats, which has important implications for the long-term survival of the little brown myotis in eastern North America. PMID:26064604

Sex and hibernaculum temperature predict survivorship in white-nose syndrome affected little brown myotis (Myotis lucifugus).

Science.gov (United States)

Grieneisen, Laura E; Brownlee-Bouboulis, Sarah A; Johnson, Joseph S; Reeder, DeeAnn M

2015-02-01

White-nose syndrome (WNS), an emerging infectious disease caused by the novel fungus Pseudogymnoascus destructans, has devastated North American bat populations since its discovery in 2006. The little brown myotis, Myotis lucifugus, has been especially affected. The goal of this 2-year captive study was to determine the impact of hibernacula temperature and sex on WNS survivorship in little brown myotis that displayed visible fungal infection when collected from affected hibernacula. In study 1, we found that WNS-affected male bats had increased survival over females and that bats housed at a colder temperature survived longer than those housed at warmer temperatures. In study 2, we found that WNS-affected bats housed at a colder temperature fared worse than unaffected bats. Our results demonstrate that WNS mortality varies among individuals, and that colder hibernacula are more favourable for survival. They also suggest that female bats may be more negatively affected by WNS than male bats, which has important implications for the long-term survival of the little brown myotis in eastern North America.

Temperature-dependent striped antiferromagnetism of LaFeAsO in a Green's function approach

International Nuclear Information System (INIS)

Liu Guibin; Liu Banggui

2009-01-01

We use a Green's function method to study the temperature-dependent average moment and magnetic phase-transition temperature of the striped antiferromagnetism of LaFeAsO, and other similar compounds, as the parents of FeAs-based superconductors. We consider the nearest and the next-nearest couplings in the FeAs layer, and the nearest coupling for inter-layer spin interaction. The dependence of the transition temperature T N and the zero-temperature average spin on the interaction constants is investigated. We obtain an analytical expression for T N and determine our temperature-dependent average spin from zero temperature to T N in terms of unified self-consistent equations. For LaFeAsO, we obtain a reasonable estimation of the coupling interactions with the experimental transition temperature T N = 138 K. Our results also show that a non-zero antiferromagnetic (AFM) inter-layer coupling is essential for the existence of a non-zero T N , and the many-body AFM fluctuations reduce substantially the low-temperature magnetic moment per Fe towards the experimental value. Our Green's function approach can be used for other FeAs-based parent compounds and these results should be useful to understand the physical properties of FeAs-based superconductors.

The effect of confinement on the temperature dependence of the excitonic transition energy in GaAs/AlxGa1-xAs quantum wells

International Nuclear Information System (INIS)

Silva, M A T da; Morais, R R O; Dias, I F L; Lourenco, S A; Duarte, J L; Laureto, E; Quivy, A A; Silva, E C F da

2008-01-01

We determined by means of photoluminescence measurements the dependence on temperature of the transition energy of excitons in GaAs/Al x Ga 1-x As quantum wells with different alloy concentrations (with different barrier heights). Using a fitting procedure, we determined the parameters which describe the behavior of the excitonic transition energy as a function of temperature according to three different theoretical models. We verified that the temperature dependence of the excitonic transition energy does not only depend on the GaAs material but also depends on the barrier material, i.e. on the alloy composition. The effect of confinement on the temperature dependence of the excitonic transition is discussed

On the temperature dependence of flammability limits of gases.

Science.gov (United States)

Kondo, Shigeo; Takizawa, Kenji; Takahashi, Akifumi; Tokuhashi, Kazuaki

2011-03-15

Flammability limits of several combustible gases were measured at temperatures from 5 to 100 °C in a 12-l spherical flask basically following ASHRAE method. The measurements were done for methane, propane, isobutane, ethylene, propylene, dimethyl ether, methyl formate, 1,1-difluoroethane, ammonia, and carbon monoxide. As the temperature rises, the lower flammability limits are gradually shifted down and the upper limits are shifted up. Both the limits shift almost linearly to temperature within the range examined. The linear temperature dependence of the lower flammability limits is explained well using a limiting flame temperature concept at the lower concentration limit (LFL)--'White's rule'. The geometric mean of the flammability limits has been found to be relatively constant for many compounds over the temperature range studied (5-100 °C). Based on this fact, the temperature dependence of the upper flammability limit (UFL) can be predicted reasonably using the temperature coefficient calculated for the LFL. However, some compounds such as ethylene and dimethyl ether, in particular, have a more complex temperature dependence. Copyright © 2011 Elsevier B.V. All rights reserved.

A nanoscale temperature-dependent heterogeneous nucleation theory

International Nuclear Information System (INIS)

Cao, Y. Y.; Yang, G. W.

2015-01-01

Classical nucleation theory relies on the hypothetical equilibrium of the whole nucleation system, and neglects the thermal fluctuations of the surface; this is because the high entropic gains of the (thermodynamically extensive) surface would lead to multiple stable states. In fact, at the nanometer scale, the entropic gains of the surface are high enough to destroy the stability of the thermal equilibrium during nucleation, comparing with the whole system. We developed a temperature-dependent nucleation theory to elucidate the heterogeneous nucleation process, by considering the thermal fluctuations based on classical nucleation theory. It was found that the temperature not only affected the phase transformation, but also influenced the surface energy of the nuclei. With changes in the Gibbs free energy barrier, nucleation behaviors, such as the nucleation rate and the critical radius of the nuclei, showed temperature-dependent characteristics that were different from those predicted by classical nucleation theory. The temperature-dependent surface energy density of a nucleus was deduced based on our theoretical model. The agreement between the theoretical and experimental results suggested that the developed nucleation theory has the potential to contribute to the understanding and design of heterogeneous nucleation at the nanoscale

Analysis of genes involved in sex determination of fishes by phenol-emulsion method

Energy Technology Data Exchange (ETDEWEB)

Nakayama, Ichiro; Nagoya, Hiroyuki; Okamoto, Hiroyuki; Araki, Kazuo [National Research Inst. of Aquaculture, Mie (Japan)

1998-02-01

With an aim to clarify the mechanism of sex determination common to vertebrates, the genes presumed to mediate the sex determination were analyzed through cDNA subtraction by phenol-emulsion method. A total RNA was extracted from male juvenile Amago, a kind of oncorhynchus and cDNA was synthesized using mRNA fractionated by oligo-dT column. The male-specific genes expressed in the stage of sex determination was isolated through incorporation to PVC-derived vector. Thus obtained genes were confirmed to be male-specific by Southern hybridization. The results of the screening for the subtracted products indicate that neither of the male-specific clones detected in this study was novel. Previous studies on sex discrimination based on mitochondrial DNA suggested that Sakuramasu and Amago belong in the same species, Oncorhynchus masou masou and the present results show that DNA sequence for male-derived GH pseudo-gene is partially different between the two fishes. (M.N.)

Single locus complementary sex determination in Hymenoptera: an "unintelligent" design?

Directory of Open Access Journals (Sweden)

Driessen Gerard

2006-01-01

Full Text Available Abstract The haplodiploid sex determining mechanism in Hymenoptera (males are haploid, females are diploid has played an important role in the evolution of this insect order. In Hymenoptera sex is usually determined by a single locus, heterozygotes are female and hemizygotes are male. Under inbreeding, homozygous diploid and sterile males occur which form a genetic burden for a population. We review life history and genetical traits that may overcome the disadvantages of single locus complementary sex determination (sl-CSD. Behavioural adaptations to avoid matings between relatives include active dispersal from natal patches and mating preferences for non-relatives. In non-social species, temporal and spatial segregation of male and female offspring reduces the burden of sl-CSD. In social species, diploid males are produced at the expense of workers and female reproductives. In some social species, diploid males and diploid male producing queens are killed by workers. Diploid male production may have played a role in the evolution or maintenance of polygyny (multiple queens and polyandry (multiple mating. Some forms of thelytoky (parthenogenetic female production increase homozygosity and are therefore incompatible with sl-CSD. We discuss a number of hypothetical adaptations to sl-CSD which should be considered in future studies of this insect order.

Temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with a soft on-site potential.

Science.gov (United States)

Yang, Linlin; Li, Nianbei; Li, Baowen

2014-12-01

The temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with soft on-site potential (soft-KG) are investigated systematically. Similarly to the previously studied hard-KG lattices, the existence of renormalized phonons is also confirmed in soft-KG lattices. In particular, the temperature dependence of the renormalized phonon frequency predicted by a classical field theory is verified by detailed numerical simulations. However, the thermal conductivities of soft-KG lattices exhibit the opposite trend in temperature dependence in comparison with those of hard-KG lattices. The interesting thing is that the temperature-dependent thermal conductivities of both soft- and hard-KG lattices can be interpreted in the same framework of effective phonon theory. According to the effective phonon theory, the exponents of the power-law dependence of the thermal conductivities as a function of temperature are only determined by the exponents of the soft or hard on-site potentials. These theoretical predictions are consistently verified very well by extensive numerical simulations.

Temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with a soft on-site potential

Science.gov (United States)

Yang, Linlin; Li, Nianbei; Li, Baowen

2014-12-01

The temperature-dependent thermal conductivities of one-dimensional nonlinear Klein-Gordon lattices with soft on-site potential (soft-KG) are investigated systematically. Similarly to the previously studied hard-KG lattices, the existence of renormalized phonons is also confirmed in soft-KG lattices. In particular, the temperature dependence of the renormalized phonon frequency predicted by a classical field theory is verified by detailed numerical simulations. However, the thermal conductivities of soft-KG lattices exhibit the opposite trend in temperature dependence in comparison with those of hard-KG lattices. The interesting thing is that the temperature-dependent thermal conductivities of both soft- and hard-KG lattices can be interpreted in the same framework of effective phonon theory. According to the effective phonon theory, the exponents of the power-law dependence of the thermal conductivities as a function of temperature are only determined by the exponents of the soft or hard on-site potentials. These theoretical predictions are consistently verified very well by extensive numerical simulations.

Sex determination in the Lesser Flamingo ( Phoenicopterus minor ...

African Journals Online (AJOL)

PCR amplification of the CHD-Z and CHD-W genes using DNA extracted from the blood samples was used to determine the sex of each bird. There were significant differences in mass and tarsus length among the three age groups, indicating that Lesser Flamingos continue to grow in skeletal size and mass between ...

Commentary Sex determination

Indian Academy of Sciences (India)

PRAKASH KUMAR G

2008-01-31

Jan 31, 2008 ... years old (Charnier 1966 reported it in an African agamid lizard), although it was ... people's attention in Susumu Ohno's now famous book on .... If they do enhance male and female fitness, sex chromosomes would then be.

Calculated temperature dependence of elastic constants and phonon dispersion of hcp and bcc beryllium

Science.gov (United States)

Hahn, Steven; Arapan, Sergiu; Harmon, Bruce; Eriksson, Olle

2011-03-01

Conventional first principle methods for calculating lattice dynamics are unable to calculate high temperature thermophysical properties of materials containing modes that are entropically stabilized. In this presentation we use a relatively new approach called self-consistent ab initio lattice dynamics (SCAILD) to study the hcp to bcc transition (1530 K) in beryllium. The SCAILD method goes beyond the harmonic approximation to include phonon-phonon interactions and produces a temperature-dependent phonon dispersion. In the high temperature bcc structure, phonon-phonon interactions dynamically stabilize the N-point phonon. Fits to the calculated phonon dispersion were used to determine the temperature dependence of the elastic constants in the hcp and bcc phases. Work at the Ames Laboratory was supported by the Department of Energy-Basic Energy Sciences under Contract No. DE-AC02-07CH11358.

Temperature dependence of the elastocaloric effect in natural rubber

Energy Technology Data Exchange (ETDEWEB)

Xie, Zhongjian, E-mail: zhongjian.xie521@gmail.com; Sebald, Gael; Guyomar, Daniel

2017-07-12

The temperature dependence of the elastocaloric (eC) effect in natural rubber (NR) has been studied. This material exhibits a large eC effect over a broad temperature range from 0 °C to 49 °C. The maximum adiabatic temperature change (ΔT) occurred at 10 °C and the behavior could be predicted by the temperature dependence of the strain-induced crystallization (SIC) and the temperature-induced crystallization (TIC). The eC performance of NR was then compared with that of shape memory alloys (SMAs). This study contributes to the SIC research of NR and also broadens the application of elastomers. - Highlights: • A large elastocaloric effect over a broad temperature range was found in natural rubber (NR). • The caloric performance of NR was compared with that of shape memory alloys. • The temperature dependence of the elastocaloric effect in NR can be prediced by the theory of strain-induced crystallization.

Label-free detection of sex determining region Y (SRY) via capacitive biosensor

KAUST Repository

Sivashankar, Shilpa

2016-10-20

In this work, we present for the first time, the use of a simple fractal capacitive biosensor for the quantification and detection of sex-determining region Y (SRY) genes. This section of genetic code, which is found on the Y chromosome, finds importance for study as it causes fetuses to develop characteristics of male sex-like gonads when a mutation occurs. It is also an important genetic code in men, and disorders involving the SRY gene can cause infertility and sexual malfunction that lead to a variety of gene mutational disorders. We have therefore designed silicon-based, label-free fractal capacitive biosensors to quantify various proteins and genes. We take advantage of a good dielectric material, Parylene C for enhancing the performance of the sensors. We have integrated these sensors with a simple microchannel for easy handling of fluids on the detection area. The read-out value of an Agilent LCR meter used to measure capacitance of the sensor at a frequency of 1 MHz determined gene specificity and gene quantification. These data revealed that the capacitance measurement of the capacitive biosensor for the SRY gene depended on both the target and the concentration of DNA. The experimental outcomes in the present study can be used to detect DNA and its variations in crucial fields that have a great impact on our daily lives, such as clinical and veterinary diagnostics, industrial and environmental testing and forensic sciences.

Theory of temperature dependent photoemission spectrum of heavy fermion semiconductors

International Nuclear Information System (INIS)

Riseborough, P.S.

1998-01-01

The heavy fermion semiconductors are a class of strongly correlated materials, that at high temperatures show properties similar to those of heavy fermion materials, but at low temperatures show a cross-over into a semi-conducting state. The low temperature insulating state is characterized by an anomalously small energy gap, varying between 10 and 100 K. The smallness of the gap is attributed to the result of a many-body renormalization, and is temperature dependent. The temperature dependence of the electronic spectral density of states is calculated, using the Anderson lattice model at half filling. The spectrum is calculated to second order in 1/N, where N is the degeneracy of the 'f' orbitals, using a slave boson technique. The system is an indirect gap semi-conductor, with an extremely temperature dependent electronic spectral density A(k, ω). The indirect gap is subject to a temperature dependent many-body renormalization, and leads to a sharp temperature dependent structure in the angle resolved photo-emission spectrum at the indirect threshold. The theoretical predictions are compared with experimental observations on FeSi. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd)

DETERMINING UNDISTURBED GROUND TEMPERATURE AS PART OF SHALLOW GEOTHERMAL RESOURCES ASSESSMENT

Directory of Open Access Journals (Sweden)

Tomislav Kurevija

2010-12-01

Full Text Available The undisturbed ground temperature is one of the key thermogeological parameters for the assessment and utilization of shallow geothermal resources. Geothermal energy is the type of energy which is stored in the ground where solar radiation has no effect. The depth at which the undisturbed ground temperature occurs, independent of seasonal changes in the surface air temperature, is functionally determined by climate parameters and thermogeological properties. In deeper layers, the increase of ground temperature depends solely on geothermal gradient. Determining accurate values of undisturbed ground temperature and depth of occurrence is crucial for the correct sizing of a borehole heat exchanger as part of the ground-source heat pump system, which is considered the most efficient technology for utilising shallow geothermal resources. The purpose of this paper is to define three specific temperature regions, based on the measured ground temperature data collected from the main meteorological stations in Croatia. The three regions are: Northern Croatia, Adriatic region, and the regions of Lika and Gorski Kotar.

B chromosomes have a functional effect on female sex determination in Lake Victoria cichlid fishes.

Directory of Open Access Journals (Sweden)

Kohta Yoshida

2011-08-01

Full Text Available The endemic cichlid fishes in Lake Victoria are a model system for speciation through adaptive radiation. Although the evolution of the sex-determination system may also play a role in speciation, little is known about the sex-determination system of Lake Victoria cichlids. To understand the evolution of the sex-determination system in these fish, we performed cytogenetic analysis in 11 cichlid species from Lake Victoria. B chromosomes, which are present in addition to standard chromosomes, were found at a high prevalence rate (85% in these cichlids. In one species, B chromosomes were female-specific. Cross-breeding using females with and without the B chromosomes demonstrated that the presence of the B chromosomes leads to a female-biased sex ratio in this species. Although B chromosomes were believed to be selfish genetic elements with little effect on phenotype and to lack protein-coding genes, the present study provides evidence that B chromosomes have a functional effect on female sex determination. FISH analysis using a BAC clone containing B chromosome DNA suggested that the B chromosomes are derived from sex chromosomes. Determination of the nucleotide sequences of this clone (104.5 kb revealed the presence of several protein-coding genes in the B chromosome, suggesting that B chromosomes have the potential to contain functional genes. Because some sex chromosomes in amphibians and arthropods are thought to be derived from B chromosomes, the B chromosomes in Lake Victoria cichlids may represent an evolutionary transition toward the generation of sex chromosomes.

Sex-dependent effects of stress on brain correlates to empathy for pain.

Science.gov (United States)

Gonzalez-Liencres, Cristina; Breidenstein, Anja; Wolf, Oliver T; Brüne, Martin

2016-07-01

Empathy is a fundamental attribute required for appropriate social functioning. The extent to which we empathize with others in pain is influenced by numerous factors. Being highly social species, humans face social stress on a regular basis, which undoubtedly affects how we react to our environment. It is not yet known how social stress may modulate our neural mechanisms when we empathize with others in painful circumstances, and its effects on empathic behavior are still unclear. For this reason, we recorded the electroencephalography (EEG) of healthy men and women, half of which were previously exposed to psychosocial stress, while they observed photographs of hands in painful and neutral situations. At the behavioral level, stress induced higher unpleasantness ratings to painful stimuli, and lower ratings to neutral pictures, independent of sex. At the neurophysiological level, we found that early (N110 over fronto-central sites) event-related potentials (ERPs) were not affected by stress, while late (P3 over centro-parietal regions) components showed a sex-dependent differential effect of stress. Correlation analyses further indicated a strong association between N110 with trait markers of empathy in all participants, while P3 was associated with the change in cortisol in stressed males. Our findings suggest that sex-dependent effects of social stress on the neural responses to empathy for pain give rise to comparable behaviors in men and women in the paradigm we employed, implying that each sex may engage in distinct mechanisms to cope with stress. Moreover, stress seems to modulate late neural mechanisms of empathy but not our early perception. Copyright © 2016 Elsevier B.V. All rights reserved.

Maternal prenatal cortisol predicts infant negative emotionality in a sex-dependent manner.

Science.gov (United States)

Braithwaite, Elizabeth C; Pickles, Andrew; Sharp, Helen; Glover, Vivette; O'Donnell, Kieran J; Tibu, Florin; Hill, Jonathan

2017-06-01

Prenatal stress influences fetal developmental trajectories, which may implicate glucocorticoid mechanisms. There is also emerging evidence that effects of prenatal stress on offspring development are sex-dependent. However, little is known about the prospective relationship between maternal prenatal cortisol levels and infant behaviour, and whether it may be different in male and female infants. We sought to address this question using data from a prospective longitudinal cohort, stratified by risk. The Wirral Child Health and Development Study (WCHADS) cohort (n=1233) included a stratified random sub-sample (n=216) who provided maternal saliva samples, assayed for cortisol, at home over two days at 32weeks of pregnancy (on waking, 30-min post-waking and during the evening) and a measure of infant negative emotionality from the Neonatal Behavioural Assessment Scale (NBAS) at five weeks-of-age. General population estimates of associations among measures were obtained using inverse probability weights. Maternal prenatal cortisol sampled on waking predicted infant negative emotionality in a sex-dependent manner (interaction term, p=0.005); female infants exposed to high levels of prenatal cortisol were more negative (Beta=0.440, p=0.042), whereas male infants were less negative (Beta=-0.407, p=0.045). There was no effect of the 30-min post-waking measure or evening cortisol. Our findings add to an emerging body of work that has highlighted sex differences in fetal programming, whereby females become more reactive following prenatal stress, and males less reactive. A more complete understanding of sex-specific developmental trajectories in the context of prenatal stress is essential for the development of targeted prevention strategies. Copyright © 2017. Published by Elsevier Inc.

Temperature dependence of bulk viscosity in water using acoustic spectroscopy

International Nuclear Information System (INIS)

Holmes, M J; Parker, N G; Povey, M J W

2011-01-01

Despite its fundamental role in the dynamics of compressible fluids, bulk viscosity has received little experimental attention and there remains a paucity of measured data. Acoustic spectroscopy provides a robust and accurate approach to measuring this parameter. Working from the Navier-Stokes model of a compressible fluid one can show that the bulk viscosity makes a significant and measurable contribution to the frequency-squared acoustic attenuation. Here we employ this methodology to determine the bulk viscosity of Millipore water over a temperature range of 7 to 50 0 C. The measured attenuation spectra are consistent with the theoretical predictions, while the bulk viscosity of water is found to be approximately three times larger than its shear counterpart, reinforcing its significance in acoustic propagation. Moreover, our results demonstrate that this technique can be readily and generally applied to fluids to accurately determine their temperature dependent bulk viscosities.

A heritable component in sex ratio and caste determination in a Cardiocondyla ant

Directory of Open Access Journals (Sweden)

Heinze Jürgen

2009-10-01

Full Text Available Abstract Studies on sex ratios in social insects provide among the most compelling evidence for the importance of kin selection in social evolution. The elegant synthesis of Fisher's sex ratio principle and Hamilton's inclusive fitness theory predicts that colony-level sex ratios vary with the colonies' social and genetic structures. Numerous empirical studies in ants, bees, and wasps have corroborated these predictions. However, the evolutionary optimization of sex ratios requires genetic variation, but one fundamental determinant of sex ratios - the propensity of female larvae to develop into young queens or workers ("queen bias" - is thought to be largely controlled by the environment. Evidence for a genetic influence on sex ratio and queen bias is as yet restricted to a few taxa, in particular hybrids. Because of the very short lifetime of their queens, ants of the genus Cardiocondyla are ideal model systems for the study of complete lifetime reproductive success, queen bias, and sex ratios. We found that lifetime sex ratios of the ant Cardiocondyla kagutsuchi have a heritable component. In experimental single-queen colonies, 22 queens from a genetic lineage with a highly female-biased sex ratio produced significantly more female-biased offspring sex ratios than 16 queens from a lineage with a more male-biased sex ratio (median 91.5% vs. 58.5% female sexuals. Sex ratio variation resulted from different likelihood of female larvae developing into sexuals (median 50% vs. 22.6% female sexuals even when uniformly nursed by workers from another colony. Consistent differences in lifetime sex ratios and queen bias among queens of C. kagutsuchi suggest that heritable, genetic or maternal effects strongly affect caste determination. Such variation might provide the basis for adaptive evolution of queen and worker strategies, though it momentarily constrains the power of workers and queens to optimize caste ratios.

A heritable component in sex ratio and caste determination in a Cardiocondyla ant.

Science.gov (United States)

Frohschammer, Sabine; Heinze, Jürgen

2009-10-28

Studies on sex ratios in social insects provide among the most compelling evidence for the importance of kin selection in social evolution. The elegant synthesis of Fisher's sex ratio principle and Hamilton's inclusive fitness theory predicts that colony-level sex ratios vary with the colonies' social and genetic structures. Numerous empirical studies in ants, bees, and wasps have corroborated these predictions. However, the evolutionary optimization of sex ratios requires genetic variation, but one fundamental determinant of sex ratios - the propensity of female larvae to develop into young queens or workers ("queen bias") - is thought to be largely controlled by the environment. Evidence for a genetic influence on sex ratio and queen bias is as yet restricted to a few taxa, in particular hybrids.Because of the very short lifetime of their queens, ants of the genus Cardiocondyla are ideal model systems for the study of complete lifetime reproductive success, queen bias, and sex ratios. We found that lifetime sex ratios of the ant Cardiocondyla kagutsuchi have a heritable component. In experimental single-queen colonies, 22 queens from a genetic lineage with a highly female-biased sex ratio produced significantly more female-biased offspring sex ratios than 16 queens from a lineage with a more male-biased sex ratio (median 91.5% vs. 58.5% female sexuals). Sex ratio variation resulted from different likelihood of female larvae developing into sexuals (median 50% vs. 22.6% female sexuals) even when uniformly nursed by workers from another colony.Consistent differences in lifetime sex ratios and queen bias among queens of C. kagutsuchi suggest that heritable, genetic or maternal effects strongly affect caste determination. Such variation might provide the basis for adaptive evolution of queen and worker strategies, though it momentarily constrains the power of workers and queens to optimize caste ratios.

A High-Fat Diet Causes Impairment in Hippocampal Memory and Sex-Dependent Alterations in Peripheral Metabolism

Directory of Open Access Journals (Sweden)

Erica L. Underwood

2016-01-01

Full Text Available While high-fat diets are associated with rising incidence of obesity/type-2 diabetes and can induce metabolic and cognitive deficits, sex-dependent comparisons are rarely systematically made. Effects of exclusive consumption of a high-fat diet (HFD on systemic metabolism and on behavioral measures of hippocampal-dependent memory were compared in young male and female LE rats. Littermates were fed from weaning either a HFD or a control diet (CD for 12 wk prior to testing. Sex-different effects of the HFD were observed in classic metabolic signs associated with type-2 diabetes. Males fed the HFD became obese, and had elevated fasted blood glucose levels, elevated corticosterone, and impaired glucose-tolerance, while females on the HFD exhibited only elevated corticosterone. Regardless of peripheral metabolism alteration, rats of both sexes fed the HFD were equally impaired in a spatial object recognition memory task associated with impaired hippocampal function. While the metabolic changes reported here have been characterized previously in males, the set of diet-induced effects observed here in females are novel. Impaired memory can have significant cognitive consequences, over the short-term and over the lifespan. A significant need exists for comparative research into sex-dependent differences underlying obesity and metabolic syndromes relating systemic, cognitive, and neural plasticity mechanisms.

Observation of a ZZW female in a natural population: implications for avian sex determination.

Science.gov (United States)

Arit, D; Bensch, S; Hansson, B; Hasselquist, D; Westerdahl, H

2004-01-01

Avian sex determination is chromosomal; however, the underlying mechanisms are not yet understood. There is no conclusive evidence for either of two proposed mechanisms: a dominant genetic switch or a dosage mechanism. No dominant sex-determining gene on the female-specific W chromosome has been found. Birds lack inactivation of one of the Z chromosomes in males, but seem to compensate for a double dose of Z-linked genes by other mechanisms. Recent studies showing female-specific expression of two genes may support an active role of the W chromosome. To resolve the question of avian sex determination the investigation of birds with a 2A: ZZW or 2A: ZO genotype would be decisive. Here, we report the case of an apparent 2A: ZZW great reed warbler (Acrocephalus arundinaceus) female breeding in a natural population, which was detected using Z-linked microsatellites. Our data strongly suggest a role of W-linked genes in avian sex determination. PMID:15252998

Using Check-All-That-Apply (CATA) method for determining product temperature-dependent sensory-attribute variations: A case study of cooked rice.

Science.gov (United States)

Pramudya, Ragita C; Seo, Han-Seok

2018-03-01

Temperatures of most hot or cold meal items change over the period of consumption, possibly influencing sensory perception of those items. Unlike temporal variations in sensory attributes, product temperature-induced variations have not received much attention. Using a Check-All-That-Apply (CATA) method, this study aimed to characterize variations in sensory attributes over a wide range of temperatures at which hot or cold foods and beverages may be consumed. Cooked milled rice, typically consumed at temperatures between 70 and 30°C in many rice-eating countries, was used as a target sample in this study. Two brands of long-grain milled rice were cooked and randomly presented at 70, 60, 50, 40, and 30°C. Thirty-five CATA terms for cooked milled rice were generated. Eighty-eight untrained panelists were asked to quickly select all the CATA terms that they considered appropriate to characterize sensory attributes of cooked rice samples presented at each temperature. Proportions of selection by panelists for 13 attributes significantly differed among the five temperature conditions. "Product temperature-dependent sensory-attribute variations" differed with two brands of milled rice grains. Such variations in sensory attributes, resulted from both product temperature and rice brand, were more pronounced among panelists who more frequently consumed rice. In conclusion, the CATA method can be useful for characterizing "product temperature-dependent sensory attribute variations" in cooked milled-rice samples. Further study is needed to examine whether the CATA method is also effective in capturing "product temperature-dependent sensory-attribute variations" in other hot or cold foods and beverages. Published by Elsevier Ltd.

Missing female fetus: a micro level investigation of sex determination in a periurban area of Northern India.

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Ghosh, Rohini; Sharma, Arun Kumar

2012-01-01

A micro-level investigation of 983 pregnant women (aged 15-49 years) regarding sex determination and associated factors was carried out in a periurban region of Northern India. Among the women surveyed, 183 chose to use sex determination. The highest percentage of sex determination was among 30-39-year-old women, and general caste and family size were two risk factors associated with sex determination. Correcting imbalances in sex ratios at birth is a complex issue without easy answers, especially in patriarchal societies. Apart from raising awareness among decisionmakers, property rights in favor of women and strict vigilance and record of registration of ultrasound machines are necessary.

Temperature dependent optical properties of ZnO thin film using ellipsometry and photoluminescence

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Bouzourâa, M.-B.; Battie, Y.; Dalmasso, S.; Zaïbi, M.-A.; Oueslati, M.; En Naciri, A.

2018-05-01

We report the temperature dependence of the dielectric function, the exciton binding energy and the electronic transitions of crystallized ZnO thin film using spectroscopic ellipsometry (SE) and photoluminescence (PL). ZnO layers were prepared by sol-gel method and deposited on crystalline silicon (Si) by spin coating technique. The ZnO optical properties were determined between 300 K and 620 K. Rigorous study of optical responses was achieved in order to demonstrate the quenching exciton of ZnO as a function of temperature. Numerical technique named constrained cubic splines approximation (CCS), Tauc-Lorentz (TL) and Tanguy dispersion models were selected for the ellipsometry data modeling in order to obtain the dielectric function of ZnO. The results reveals that the exciton bound becomes widely flattening at 470 K on the one hand, and on the other that the Tanguy dispersion law is more appropriate for determining the optical responses of ZnO thin film in the temperature range of 300 K-420 K. The Tauc-Lorentz, for its part, reproduces correctly the ZnO dielectric function in 470 K-620 K temperature range. The temperature dependence of the electronic transition given by SE and PL shows that the exciton quenching was observed in 420 K-∼520 K temperature range. This quenching effect can be explained by the equilibrium between the Coulomb force of exciton and its kinetic energy in the film. The kinetic energy was found to induce three degrees of freedom of the exciton.

Evolution of the complementary sex-determination gene of honey bees: balancing selection and trans-species polymorphisms.

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Cho, Soochin; Huang, Zachary Y; Green, Daniel R; Smith, Deborah R; Zhang, Jianzhi

2006-11-01

The mechanism of sex determination varies substantively among evolutionary lineages. One important mode of genetic sex determination is haplodiploidy, which is used by approximately 20% of all animal species, including >200,000 species of the entire insect order Hymenoptera. In the honey bee Apis mellifera, a hymenopteran model organism, females are heterozygous at the csd (complementary sex determination) locus, whereas males are hemizygous (from unfertilized eggs). Fertilized homozygotes develop into sterile males that are eaten before maturity. Because homozygotes have zero fitness and because common alleles are more likely than rare ones to form homozygotes, csd should be subject to strong overdominant selection and negative frequency-dependent selection. Under these selective forces, together known as balancing selection, csd is expected to exhibit a high degree of intraspecific polymorphism, with long-lived alleles that may be even older than the species. Here we sequence the csd genes as well as randomly selected neutral genomic regions from individuals of three closely related species, A. mellifera, Apis cerana, and Apis dorsata. The polymorphic level is approximately seven times higher in csd than in the neutral regions. Gene genealogies reveal trans-species polymorphisms at csd but not at any neutral regions. Consistent with the prediction of rare-allele advantage, nonsynonymous mutations are found to be positively selected in csd only in early stages after their appearances. Surprisingly, three different hypervariable repetitive regions in csd are present in the three species, suggesting variable mechanisms underlying allelic specificities. Our results provide a definitive demonstration of balancing selection acting at the honey bee csd gene, offer insights into the molecular determinants of csd allelic specificities, and help avoid homozygosity in bee breeding.

Accurate experimental determination of the isotope effects on the triple point temperature of water. I. Dependence on the "2H abundance

International Nuclear Information System (INIS)

Faghihi, V.; Aerts-Bijma, A.T.; Jansen, H.G.; Spriensma, J.J.; Meijer, H.A.J.; Peruzzi, A.; Geel, J. van

2015-01-01

Variation in the isotopic composition of water is one of the major contributors to uncertainty in the realization of the triple point of water (TPW). Although the dependence of the TPW on the isotopic composition of the water has been known for years, there is still a lack of a detailed and accurate experimental determination of the values for the correction constants. This paper is the first of two articles (Part I and Part II) that address quantification of isotope abundance effects on the triple point temperature of water. In this paper, we describe our experimental assessment of the "2H isotope effect. We manufactured five triple point cells with prepared water mixtures with a range of "2H isotopic abundances encompassing widely the natural abundance range, while the "1"8O and "1"7O isotopic abundance were kept approximately constant and the "1"8O - "1"7O ratio was close to the Meijer-Li relationship for natural waters. The selected range of "2H isotopic abundances led to cells that realised TPW temperatures between approximately -140 μK to + 2500 μK with respect to the TPW temperature as realized by VSMOW (Vienna Standard Mean Ocean Water). Our experiment led to determination of the value for the δ"2H correction parameter of A_2_H = 673 μK/(per thousand deviation of δ"2H from VSMOW) with a combined uncertainty of 4 μK (k = 1, or 1 s). (authors)

Rate of egg maturation in marine turtles exhibits 'universal temperature dependence'.

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Weber, Sam B; Blount, Jonathan D; Godley, Brendan J; Witt, Matthew J; Broderick, Annette C

2011-09-01

1. The metabolic theory of ecology (MTE) predicts that, after correcting for body mass variation among organisms, the rates of most biological processes will vary as a universal function of temperature. However, empirical support for 'universal temperature dependence' (UTD) is currently equivocal and based on studies of a limited number of traits. 2. In many ectothermic animals, the rate at which females produce mature eggs is temperature dependent and may be an important factor in determining the costs of reproduction. 3. We tested whether the rate of egg maturation in marine turtles varies with environmental temperature as predicted by MTE, using the time separating successive clutches of individual females to estimate the rate at which eggs are formed. We also assessed the phenotypic contribution to this rate, by using radio telemetry to make repeated measurements of interclutch intervals for individual green turtles (Chelonia mydas). 4. Rates of egg maturation increased with seasonally increasing water temperatures in radio-tracked green turtles, but were not repeatable for individual females, and did not vary according to maternal body size or reproductive investment (number and size of eggs produced). 5. Using a collated data set from several different populations and species of marine turtles, we then show that a single relationship with water temperature explains most of the variation in egg maturation rates, with a slope that is statistically indistinguishable from the UTD predicted by MTE. However, several alternative statistical models also described the relationship between temperature and egg maturation rates equally parsimoniously. 6. Our results offer novel support for the MTE's predicted UTD of biological rates, although the underlying mechanisms require further study. The strong temperature dependence of egg maturation combined with the apparently weak phenotypic contribution to this rate has interesting behavioural implications in ectothermic

Inferring the temperature dependence of Beremin cleavage model parameters from the Master Curve

International Nuclear Information System (INIS)

Cao Yupeng; Hui Hu; Wang Guozhen; Xuan Fuzhen

2011-01-01

Research highlights: → Temperature dependence of Beremin model parameters is inferred by Master Curve approach. → Weibull modulus decreases while Weibull stress scale parameter increases with increasing the temperature. → Estimation of Weibull stress parameters in terms of small amounts of specimens leads to a considerable uncertainty. - Abstract: The temperature dependence of Beremin model parameters in the ductile-to-brittle transition region was addressed by employing the Master Curve. Monte Carlo simulation was performed to produce a large number of 1T fracture toughness data randomly drawn from the scatter band at a temperature of interest and thus to determine Beremin model parameters. In terms of the experimental data of a C-Mn steel (the 16MnR steel in China), results revealed that the Weibull modulus, m, decreases with temperature over the lower transition range and remains a constant in the lower-to-mid transition region. The Weibull scale parameter, σ u , increases with temperature over the temperature range of investigated. A small sample may lead to a considerable uncertainty in estimates of the Weibull stress parameters. However, no significant difference was observed for the average of Weibull stress parameters from different sample sizes.

Temperature dependence in magnetic particle imaging

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Wells, James; Paysen, Hendrik; Kosch, Olaf; Trahms, Lutz; Wiekhorst, Frank

2018-05-01

Experimental results are presented demonstrating how temperature can influence the dynamics of magnetic nanoparticles (MNPs) in liquid suspension, when exposed to alternating magnetic fields in the kilohertz frequency range. The measurements used to probe the nanoparticle systems are directly linked to both the emerging biomedical technique of magnetic particle imaging (MPI), and to the recently proposed concept of remote nanoscale thermometry using MNPs under AC field excitation. Here, we report measurements on three common types of MNPs, two of which are currently leading candidates for use as tracers in MPI. Using highly-sensitive magnetic particle spectroscopy (MPS), we demonstrate significant and divergent thermal dependences in several key measures used in the evaluation of MNP dynamics for use in MPI and other applications. The temperature range studied was between 296 and 318 Kelvin, making our findings of particular importance for MPI and other biomedical technologies. Furthermore, we report the detection of the same temperature dependences in measurements conducted using the detection coils within an operational preclinical MPI scanner. This clearly shows the importance of considering temperature during MPI development, and the potential for temperature-resolved MPI using this system. We propose possible physical explanations for the differences in the behaviors observed between the different particle types, and discuss our results in terms of the opportunities and concerns they raise for MPI and other MNP based technologies.

Experimental determination of monoethanolamine protonation constant and its temperature dependency

Directory of Open Access Journals (Sweden)

Ma’mun Sholeh

2017-01-01

Full Text Available Carbon dioxide as one of the major contributors to the global warming problem is produced in large quantities by many important industries and its emission seems to rise from year to year. Aminebased absorption is one of the methods to capture CO2 from its sources. As a reactive system, mass transfer and chemical reaction take place simultaneously. In a vapor-liquid equilibrium model for the CO2-amine-water system, some parameters such as mass transfer coefficients and chemical equilibrium constants need to be known. However, some parameters could be determined experimentally and the rests could be regressed from the model. The protonation constant (pKa, as one of the model parameters, could then be measured experimentally. The purpose of this study is to measure the pKa of monoethanolamine (MEA at a range of temperatures from 303 to 330K by a potentiometric titration method. The experimental data obtained were in a good agreement with the literature data. The pKa data from this work together with those from the literature were then correlated in an empirical correlation to be used for future research.

Temperature Dependence of Electrical Resistance of Woven Melt-Infiltrated SiCf/SiC Ceramic Matrix Composites

Science.gov (United States)

Appleby, Matthew P.; Morscher, Gregory N.; Zhu, Dongming

2016-01-01

Recent studies have successfully shown the use of electrical resistance (ER)measurements to monitor room temperature damage accumulation in SiC fiber reinforced SiC matrix composites (SiCf/SiC) Ceramic Matrix Composites (CMCs). In order to determine the feasibility of resistance monitoring at elevated temperatures, the present work investigates the temperature dependent electrical response of various MI (Melt Infiltrated)-CVI (Chemical Vapor Infiltrated) SiC/SiC composites containing Hi-Nicalon Type S, Tyranno ZMI and SA reinforcing fibers. Test were conducted using a commercially available isothermal testing apparatus as well as a novel, laser-based heating approach developed to more accurately simulate thermomechanical testing of CMCs. Secondly, a post-test inspection technique is demonstrated to show the effect of high-temperature exposure on electrical properties. Analysis was performed to determine the respective contribution of the fiber and matrix to the overall composite conductivity at elevated temperatures. It was concluded that because the silicon-rich matrix material dominates the electrical response at high temperature, ER monitoring would continue to be a feasible method for monitoring stress dependent matrix cracking of melt-infiltrated SiC/SiC composites under high temperature mechanical testing conditions. Finally, the effect of thermal gradients generated during localized heating of tensile coupons on overall electrical response of the composite is determined.