Sex Genotype Research Articles

Epigenetics of sex determination in mammals.

Epigenetics is the study of changes in gene function that cannot be explained by changes in DNA sequence. A mammalian body contains more than two hundred types of cells. Since all of them are derived from a single fertilized egg, their genotypes are identical. However, the gene expression patterns are different between the cell types, indicating that each cell type has unique own "epigenotype". Epigenetic gene regulation mechanisms essentially contribute to various processes of mammalian development. The essence of epigenetic regulation is the structural change of chromatin to modulate gene activity in a spatiotemporal manner. DNA methylation and histone modifications are the major epigenetic mechanisms. Sex determination is the process for gender establishment. There are two types of sex-determining mechanisms in animals, environmental sex determination (ESD) and genotypic sex determination (GSD). Recent studies have provided some evidence that epigenetic mechanisms play indispensable roles in ESD and GSD. Some fishes undergo ESD, in which DNA methylation is essentially involved. GSD is employed in therian mammals, where Sry (sex-determining region on the Y chromosome) triggers testis differentiation from undifferentiated gonads. Sry expression is tightly regulated in a spatiotemporal manner. A recent study demonstrated that histone modification is involved in Sry regulation. In this review, we discuss the role of epigenetic mechanisms for sex determination in mammals and other vertebrates.

Female heterogamety in Madagascar chameleons (Squamata: Chamaeleonidae: Furcifer): differentiation of sex and neo-sex chromosomes.

Amniotes possess variability in sex determining mechanisms, however, this diversity is still only partially known throughout the clade and sex determining systems still remain unknown even in such a popular and distinctive lineage as chameleons (Squamata: Acrodonta: Chamaeleonidae). Here, we present evidence for female heterogamety in this group. The Malagasy giant chameleon (Furcifer oustaleti) (chromosome number 2n = 22) possesses heteromorphic Z and W sex chromosomes with heterochromatic W. The panther chameleon (Furcifer pardalis) (2n = 22 in males, 21 in females), the second most popular chameleon species in the world pet trade, exhibits a rather rare Z1Z1Z2Z2/Z1Z2W system of multiple sex chromosomes, which most likely evolved from W-autosome fusion. Notably, its neo-W chromosome is partially heterochromatic and its female-specific genetic content has expanded into the previously autosomal region. Showing clear evidence for genotypic sex determination in the panther chameleon, we resolve the long-standing question of whether or not environmental sex determination exists in this species. Together with recent findings in other reptile lineages, our work demonstrates that female heterogamety is widespread among amniotes, adding another important piece to the mosaic of knowledge on sex determination in amniotes needed to understand the evolution of this important trait.

Pattern and scale of geographic variation in environmental sex determination in the Atlantic silverside, Menidia menidia.

The Atlantic silverside, Menidia menidia (Pisces: Atherinidae), exhibits an exceptionally high level of clinal variation in sex determination across its geographic range. Previous work suggested linear changes in the level of temperature-dependent sex determination (TSD) with increasing latitude. Based on comparisons at 31 sites encompassing the entire species' range, we find that the change in level of TSD with latitude is instead highly nonlinear. The level of TSD is uniformly high in the south (Florida to New Jersey), then declines rapidly into the northern Gulf of Maine where genotypic sex determination (GSD) predominates and then rebounds to moderate levels of TSD in the northern-most populations of the Gulf of St. Lawrence. Major latitudinal breakpoints occur in central New Jersey (40(o)N) and the northern Gulf of Maine (44(o)N). No populations display pure TSD or GSD. Length of the growing season is the likely agent of selection driving variation in TSD with a threshold at 210 days. Because gene flow among populations is high, such distinct patterns of geographic variation in TSD/GSD are likely maintained by contemporary selection thereby demonstrating the adaptive fine tuning of sex determining mechanisms.

Sex reversal triggers the rapid transition from genetic to temperature-dependent sex.

Sex determination in animals is amazingly plastic. Vertebrates display contrasting strategies ranging from complete genetic control of sex (genotypic sex determination) to environmentally determined sex (for example, temperature-dependent sex determination). Phylogenetic analyses suggest frequent evolutionary transitions between genotypic and temperature-dependent sex determination in environmentally sensitive lineages, including reptiles. These transitions are thought to involve a genotypic system becoming sensitive to temperature, with sex determined by gene-environment interactions. Most mechanistic models of transitions invoke a role for sex reversal. Sex reversal has not yet been demonstrated in nature for any amniote, although it occurs in fish and rarely in amphibians. Here we make the first report of reptile sex reversal in the wild, in the Australian bearded dragon (Pogona vitticeps), and use sex-reversed animals to experimentally induce a rapid transition from genotypic to temperature-dependent sex determination. Controlled mating of normal males to sex-reversed females produces viable and fertile offspring whose phenotypic sex is determined solely by temperature (temperature-dependent sex determination). The W sex chromosome is eliminated from this lineage in the first generation. The instantaneous creation of a lineage of ZZ temperature-sensitive animals reveals a novel, climate-induced pathway for the rapid transition between genetic and temperature-dependent sex determination, and adds to concern about adaptation to rapid global climate change.

Climate change overruns resilience conferred by temperature-dependent sex determination in sea turtles and threatens their survival.

Temperature-dependent sex determination (TSD) is the predominant form of environmental sex determination (ESD) in reptiles, but the adaptive significance of TSD in this group remains unclear. Additionally, the viability of species with TSD may be compromised as climate gets warmer. We simulated population responses in a turtle with TSD to increasing nest temperatures and compared the results to those of a virtual population with genotypic sex determination (GSD) and fixed sex ratios. Then, we assessed the effectiveness of TSD as a mechanism to maintain populations under climate change scenarios. TSD populations were more resilient to increased nest temperatures and mitigated the negative effects of high temperatures by increasing production of female offspring and therefore, future fecundity. That buffered the negative effect of temperature on the population growth. TSD provides an evolutionary advantage to sea turtles. However, this mechanism was only effective over a range of temperatures and will become inefficient as temperatures rise to levels projected by current climate change models. Projected global warming threatens survival of sea turtles, and the IPCC high gas concentration scenario may result in extirpation of the studied population in 50 years.

Identification of Sex Chromosomes by Means of Comparative Genomic Hybridization in a Lizard, Eremias multiocellata.

Eremias multiocellata is a viviparous lizard that is known to exhibit temperature-dependent sex determination (TSD). Conventional Giemsa staining under light microscope examination has identified the karyotype of this species to be 2 n=36 I+2 m, with no detectable heteromorphic sex chromosomes. However, a highly differentiated female-specific chromosome, W, which is homomorphic with the Z chromosome, is found in the present study by the high-resolution cytogenetic method of comparative genomic hybridization (CGH). The results show that E. multiocellata is a viviparous lizard with both TSD and ZW heterogametic sex chromosomes. Despite the fact that a different sex ratio of male offspring was found in two populations (separated by an altitude of 1400 m) in previous incubation experiments, we demonstrate, using genomic in situ hybridization (GISH), that there is no significant chromosomal loss or acquisition between the two populations. This suggests that temperature may play a more important role in lowland populations. These results most likely indicate that E. multiocellata is transitioning between the evolutionary processes of TSD and genotypic sex determination (GSD) systems, and also give clues to the effect of TSD versus GSD in this process.

Microsatellite markers for Urochloa humidicola (Poaceae) and their transferability to other Urochloa species.

BackgroundUrochloa humidicola is a warm-season grass commonly used as forage in the tropics and is recognized for its tolerance to seasonal flooding. This grass is an important forage species for the Cerrado and Amazon regions of Brazil. U. humidicola is a polyploid species with variable ploidy (6X–9X) and facultative apomixis with high phenotypic plasticity. However, this apomixis and ploidy, as well as the limited knowledge of the genetic basis of the germplasm collection, have constrained genetic breeding activities, yet microsatellite markers may enable a better understanding of the species’ genetic composition. This study aimed to develop and characterize new polymorphic microsatellite molecular markers in U. humidicola and to evaluate their transferability to other Urochloa species.FindingsA set of microsatellite markers for U. humidicola was identified from two new enriched genomic DNA libraries: the first library was constructed from a single sexual genotype and the second from a pool of eight apomictic genotypes selected on the basis of previous results. Of the 114 loci developed, 72 primer pairs presented a good amplification product, and 64 were polymorphic among the 34 genotypes tested. The number of bands per simple sequence repeat (SSR) locus ranged from 1 to 29, with a mean of 9.6 bands per locus. The mean polymorphism information content (PIC) of all loci was 0.77, and the mean discrimination power (DP) was 0.87. STRUCTURE analysis revealed differences among U. humidicola accessions, hybrids, and other Urochloa accessions. The transferability of these microsatellites was evaluated in four species of the genus, U. brizantha, U. decumbens, U. ruziziensis, and U. dictyoneura, and the percentage of transferability ranged from 58.33% to 69.44% depending on the species.ConclusionsThis work reports new polymorphic microsatellite markers for U. humidicola that can be used for breeding programs of this and other Urochloa species, including genetic linkage mapping, quantitative trait loci identification, and marker-assisted selection.

A Sex‐Determining Gene (sdY) Assay Shows Discordance between Phenotypic and Genotypic Sex in Wild Populations of Chinook Salmon

AbstractSex is determined genetically in most fishes, but the gene responsible for sex determination is not known for the vast majority of fish species, including Chinook Salmon Oncorhynchus tshawytscha. The purpose of this study was to characterize a putative sex‐determining gene (“sexually dimorphic on the Y‐chromosome” [sdY] gene) in Chinook Salmon and develop a method to test genomic DNA (gDNA) samples for genetic sex assignment. Using next‐generation sequencing and salmonid DNA sequence data from GenBank, the entire genomic organization of Chinook Salmon sdY was described. The corresponding full‐length complementary DNA (cDNA) sequence generated from total RNA was determined by using a combination of genomic‐based primers and “rapid amplification of cDNA ends” (RACE) PCR assays. A phylogenic analysis was conducted by comparing the Chinook Salmon sdY cDNA sequence with sdY sequences (GenBank) from 10 other teleost species. A multisequence alignment was performed, and a phylogenetic tree was inferred from the alignment, providing evidence for sdY identity. Based upon a TaqMan real‐time PCR assay, a genetic test for male sex using sdY was developed and tested on gDNA isolated from phenotypic female and male Chinook Salmon representing populations in Alaska, Idaho, and Washington. The results provide compelling evidence that sdY is the sex‐determining gene in Chinook Salmon. We developed a reliable assay for sdY that can be used for genetic sex assignment in this species. However, discordance between phenotype and genotype was noted in 13 of 107 phenotypic female Chinook Salmon from Alaska and Washington. Several explanations for this discordance are discussed.Received January 14, 2014; accepted November 25, 2014

ECOLOGICAL AND EVOLUTIONARY APPLICATIONS FOR ENVIRONMENTAL SEX REVERSAL OF FISH.

Environmental sex reversal (ESR), which results in a mismatch between genotypic and phenotypic sex, is well documented in numerous fish species and may be induced by chemical exposure. Historically, research involving piscine ESR has been carried out with a view to improving profitability in aquaculture or to elucidate the processes governing sex determination and sexual differentiation. However, recent studies in evolution and ecology suggest research on ESR now has much wider applications and ramifications. We begin with an overview of ESR in fish and a brief review of the traditional applications thereof. We then discuss ESR and its potential demographic consequences in wild populations. Theory even suggests sex-reversed fish may be purposefully released to manipulate population dynamics. We suggest new research directions that may prove fruitful in understanding how ESR at the individual level translates to population-level processes. In the latter portion of the review we focus on evolutionary applications of ESR. Sex-reversal studies from the aquaculture literature provide insight in to the evolvability of determinants of sexual phenotype. Additionally, induced sex reversal can provide information about the evolution of sex chromosomes and sex-linked traits. Recently, naturally occurring ESR has been implicated as a mechanism contributing to the evolution of sex chromosomes.

Sex Determination in Southern Alligator Lizards (Elgaria multicarinata; Anguidae)

Abstract: Sex in many reptiles is determined by temperature during development (temperature-dependent sex determination; TSD) rather than by an individual's genotype (genotypic sex determination; GSD). TSD has numerous ecological and evolutionary implications, and whether or not species display TSD is of conservation concern because substantial habitat and climate change have the potential to skew sex ratios. It is therefore important to describe the means by which sex is determined in reptile species. To date, the sex determination mechanism is not known for any species within the Anguidae, a diverse lizard family that is globally distributed. I used controlled incubation experiments to test the hypothesis that Southern Alligator Lizards (Elgaria multicarinata) display TSD. Offspring sex was assessed by direct examination of the gonads after incubation in one of five constant-temperature treatments (24°, 26°, 28°, 30°, and 32°C). Developmental temperature did not affect offspring sex, indicating that E....

Methyl farnesoate synthesis is necessary for the environmental sex determination in the water flea Daphnia pulex

Sex-determination systems can be divided into two groups: genotypic sex determination (GSD) and environmental sex determination (ESD). ESD is an adaptive life-history strategy that allows control of sex in response to environmental cues in order to optimize fitness. However, the molecular basis of ESD remains largely unknown. The micro crustacean Daphnia pulex exhibits ESD in response to various external stimuli. Although methyl farnesoate (MF: putative juvenile hormone, JH, in daphnids) has been reported to induce male production in daphnids, the role of MF as a sex-determining factor remains elusive due to the lack of a suitable model system for its study. Here, we establish such a system for ESD studies in D. pulex. The WTN6 strain switches from producing females to producing males in response to the shortened day condition, while the MFP strain only produces females, irrespective of day-length. To clarify whether MF has a novel physiological role as a sex-determining factor in D. pulex, we demonstrate that a MF/JH biosynthesis inhibitor suppressed male production in WTN6 strain reared under the male-inducible condition, shortened day-length. Moreover, we show that juvenile hormone acid O-methyltransferase (JHAMT), a critical enzyme of MF/JH biosynthesis, displays MF-generating activity by catalyzing farnesoic acid. Expression of the JHAMT gene increased significantly just before the MF-sensitive period for male production in the WTN6 strain, but not in the MFP strain, when maintained under male-inducible conditions. These results suggest that MF synthesis regulated by JHAMT is necessary for male offspring production in D. pulex. Our findings provide novel insights into the genetic underpinnings of ESD and they begin to shed light on the physiological function of MF as a male-fate determiner in D. pulex.

Temperature-Dependent Sex Determination Ruled Out in the Chinese Soft-Shelled Turtle (Pelodiscus sinensis) via Molecular Cytogenetics and Incubation Experiments across Populations

The sex determination mechanism for the Chinese soft-shelled turtle (Pelodiscus sinensis) is subject to controversy. Some populations have been shown to possess sex chromosomes and thus genotypic sex determination (GSD), while others were reported to exhibit temperature-dependent sex determination (TSD). To test whether TSD and GSD coexist in this species or whether populations differ in their sex-determining system, we conducted egg incubation experiments to investigate how temperature influences hatchling sex in a wide range of populations of this species in China. In parallel, we used comparative genome hybridization (CGH) to study the micro-sex chromosomes of adult P. sinensis in the 2 populations that were previously identified to be TSD. The incubation experiments showed that temperature did not affect hatchling sex in any of the studied populations. CGH indicated that turtles have micro-sex chromosomes of the female heterogametic (ZZ/ZW) system in the 2 disputed populations. These results indicate that P. sinensis is a GSD rather than a TSD species. Thus, the apparent coexistence of TSD and GSD in this species is the result of previous misdiagnosis in purportedly TSD populations.

Development of a Chinook Salmon Sex Identification SNP Assay Based on the Growth Hormone Pseudogene

Abstract Genotypic sex identification assays can provide valuable information about fish populations when phenotypic sex determination is difficult. Here we describe the development of a TaqMan® assay (Ots_SexID) designed to identify the genotypic sex by targeting a region previously examined in the growth hormone pseudogene for winter-run Chinook salmon (Oncorhynchus tshawytscha) collected from the Sacramento River and spawned at the Livingston Stone National Fish Hatchery. Accuracy of the marker was assessed by comparing genotypic sex assignments for Chinook salmon spawned at Livingston Stone National Fish hatchery in 2012 (n = 84) with phenotypic sex recorded during spawning. Genotypic sex was observed to be concordant with phenotypic sex identified using Ots_SexID in 83/84 individuals, suggesting that the assay could be used to predict phenotypic sex with ∼︀99% accuracy. To evaluate the utility of the TaqMan assay in other parts of the species’ range, we examined collections from 29 other populations ranging from Alaska to California. Genotypic sex assignments based on the assay were generally concordant with observed phenotypes, but there were some strong exceptions. These results suggest that the new assay will be very useful for Sacramento River winter-run Chinook salmon, but also highlight the importance of thoroughly testing any genotypic sex identification assay before application in a population of interest.

Fluctuating Water Temperatures Affect Development, Physiological Responses and Cause Sex Reversal in Fathead Minnows

Natural and human activities can result in both high temporal and spatial variability in water temperature. Rapid temperature changes have the potential to dramatically affect physiological processes in aquatic organisms and, due to their limited mobility, fish early life stages are particularly vulnerable to ambient temperature fluctuations. In this study, we examined how the magnitude and frequency of temperature fluctuations affect survival, growth, development, expression of thermoresponsive genes, and gonadal differentiation in fathead minnows, Pimephales promelas. We exposed individuals (0 to 4 days post fertilization) of known genotypic sex to fluctuations of Δ4 °C over 12-h, Δ8 °C over 12- and 24-h, and three stable temperatures (21, 25, and 29 °C) for up to 45 d. Expression of hsp70 in fish exposed to the highest-magnitude, highest-frequency fluctuating treatment cycled in concert with temperature and was upregulated initially during exposure, and may have contributed to temperature fluctuations having little effect on time to and size at hatching (whole-organism responses). This treatment also caused fish to undergo nondirectional sex reversal. These results indicate that hsp70 may be involved in mediating thermal stress from subdaily temperature fluctuations and that sex determination in fathead minnows can be influenced by cycling temperatures.

Implementation of drug and HIV risk counseling in MMT programs in Taiwan

s / Drug and Alcohol Dependence 146 (2015) e118–e201 e173 Sex-differences in cognition and behaviors in children with family history of substance use disorders Kristin Lee1, Lexi Pritchett1, Gro Lohaugen2,3, Shannon Kogachi1, Erin Fukaya1, Antonette Hernandez1, Caroline Jiang1, Daniel Alicata1, Thomas Ernst1, Linda Chang1 1 Medicine, University of Hawaii, Honolulu, HI, United States 2 Pediatrics and Child Rehabilitation, Norwegian University of Science and Technology, Arendal, Norway 3 Laboratory Medicine, Norwegian University of Science and Technology, Trondheim, Norway Aims: Substance use disorder (SUD) is highly heritable, but it is unclear whether SUD-related cognitive and behavioral deficits are inherited and if they are sexually dimorphic. Polymorphisms in catechol-O-methyltransferase (COMT) genes have been associated with sex-specific deficits associated with SUD. The aim is to determine the association between two COMT genotype variants, sex, and family history of SUD (FSUD) on behavioral measures and cognition in typically developing children. Methods: FSUD, externalizing behavior and total ADHD scores were reported by parents of 226 children ages 3–20 years (85 SUD: 10.1±0.5 years, 48 boys; 141 CON: 10.0±0.4 years, 74 boys). Cognitive performancewas assessed by full scale IQ (FSIQ) and the NIH Toolbox®. Saliva sampleswere genotyped for two functional COMT single nucleotide polymorphisms (SNPs): rs4680 (Val158Met) and rs165599 (near the 3’UTR region). Results: On 3-way (SNP, sex, FSUD) ANOVAs, rs165599 tended to have negative effects on ADHD scores (p=0.08) and externalizing behaviors (p=0.06), with male AA-carriers with FSUD having higher ADHD scores (p=0.10) and externalizing behaviors (p=0.03). COMT rs165599 variant tended to have a negative effect on FSIQ (p=0.08) and IQ processing speed (p=0.07), withmale AAcarriers with FSUD having the lowest scores. Regardless of FSUD, males with the rs4680 variant tended to have lower FSIQ (p=0.06), but significantly lower processing speed scores (p=0.003). Conclusions: The COMT genetic variants appear to have a greater negative influence on boys. FSUD boys with the rs165599 AA-genotype had greater ADHD symptoms and externalizing behaviors as well as lower FSIQ and slower processing speed. Both behaviors and cognitive functionmay be influenced by these genes involved in dopamine metabolism in a sex-specific manner. Financial Support: NIH (RC2-DA029475, 2K24-DA16170, U54NS56883, G12-MD007601). http://dx.doi.org/10.1016/j.drugalcdep.2014.09.386 Implementation of drug and HIV risk counseling in MMT programs in Taiwan Tony Szu-Hsien Lee1, Marek C. Chawarski2, C. Peng1, C. Hung3, D. Metzger4 1 National Taiwan Normal University, Taipei, Taiwan 2 Psychiatry, Yale School of Medicine, New Haven, CT, United States 3 Taichung Veteran General Hospital, Taichung, Taiwan 4 University of Pennsylvania, Philadelphia, PA,

Molecular evolution of Dmrt1 accompanies change of sex-determining mechanisms in reptilia.

In reptiles, sex-determining mechanisms have evolved repeatedly and reversibly between genotypic and temperature-dependent sex determination. The gene Dmrt1 directs male determination in chicken (and presumably other birds), and regulates sex differentiation in animals as distantly related as fruit flies, nematodes and humans. Here, we show a consistent molecular difference in Dmrt1 between reptiles with genotypic and temperature-dependent sex determination. Among 34 non-avian reptiles, a convergently evolved pair of amino acids encoded by sequence within exon 2 near the DM-binding domain of Dmrt1 distinguishes species with either type of sex determination. We suggest that this amino acid shift accompanied the evolution of genotypic sex determination from an ancestral condition of temperature-dependent sex determination at least three times among reptiles, as evident in turtles, birds and squamates. This novel hypothesis describes the evolution of sex-determining mechanisms as turnover events accompanied by one or two small mutations.

The sensitive period for male-to-female sex reversal begins at the embryonic stage in the Nile tilapia and is associated with the sexual genotype.

In this study, we sought to determine the mechanism of early sex reversal in a teleost by applying 4 hr feminization treatments to XY (17α-ethynylestradiol 2000 μg L(-1) ) and YY (6500 μg L(-1) ) Nile tilapia embryos on the first day post-fertilization (dpf). We then searched for changes in the expression profiles of some sex-differentiating genes in the brain (cyp19a1b, foxl2, and amh) and in sex steroids (testosterone, 17β-estradiol, and 11-ketotestosterone) concentrations during embryogenesis and gonad differentiation. No sex reversal was observed in YY individuals, whereas sex-reversal rates in XY progeny ranged from 0-60%. These results, together with the clearance profile of 17α-ethynylestradiol, confirmed the existence of an early sensitive period for sex determination that encompasses embryonic and larval development and is active prior to any sign of gonad differentiation. Estrogen treatment induced elevated expression of cyp19a1b and higher testosterone and 17β-estradiol concentrations at 4 dpf in both XY and YY individuals. foxl2 and amh were repressed at 4 dpf and their expression levels were not different between treated and control groups at 14 dpf, suggesting that foxl2 did not control cyp19a1b in the brains of tilapia embryos. Increased cyp19a1b expression in treated embryos could reflect early brain sexualization, although this difference alone cannot account for the observed sex reversal as the treatment was ineffective in YY individuals. The differential sensitivity of XY and YY genotypes to embryonic induced-feminization suggests that a sex determinant on the sex chromosomes, such as a Y repressor or an X activator, may influence sex reversal during the first steps of tilapia embryogenesis.

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

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.

PO-0401 Il-6 Polymorphism At Position-174 In Newborn Infants With Perinatal Arterial Ischaemic Stroke: Association With Adverse Outcome

Background Inflammation has been proposed as a hallmark in the pathophysiology of stroke. A functional polymorphism in the interleukin (IL)-6 gene at position-174, encoding for the pro-inflammatory cytokine IL-6, is associated with an increased risk of neonatal brain injury or development of cerebral palsy. The aim was to study whether the IL-6-174 G/C polymorphism increased the risk of perinatal arterial ischaemic stroke (PAIS) or subsequent adverse sequelae. Methods Infants born at or above 37 weeks gestation with PAIS diagnosed by neonatal MRI (n = 63) were included. Genotyping of the IL-6-174 G/C polymorphism was performed and compared to 1008 random population controls. Perinatal variables of case infants were reviewed. Results There were no differences in IL-6-174 genotype between infants with PAIS and population controls. In a multivariable analysis, independent risk factors for adverse outcome after PAIS in a middle cerebral artery territory included CG genotype (OR 5.9; 95% CI 1.02–33.9) and male sex (OR 4.2; 95% CI 1.04–17.2). Conclusion The distribution of the IL-6-174 C >G promotor polymorphism did not differ between infants with PAIS and population controls and therefore do not seem to play a role in stroke risk. However, the IL-6-174 GC genotype was more common among infants who had an adverse outcome following PAIS in the middle cerebral artery territory, suggesting that the level of inflammation does play a role in outcome after PAIS. This may be relevant for neuroprotective strategies.

Sex-biased miRNAs in gonad and their potential roles for testis development in yellow catfish.

Recently, YY super-male yellow catfish had been created by hormonal-induced sex reversal and sex-linked markers, which provides a promising research model for fish sex differentiation and gonad development, especially for testis development. MicroRNAs (miRNAs) have been revealed to play crucial roles in the gene regulation and gonad development in vertebrates. In this study, three small RNA libraries constructed from gonad tissues of XX female, XY male and YY super-male yellow catfish were sequenced. The sequencing data generated a total of 384 conserved miRNAs and 113 potential novel miRNAs, among which 23, 30 and 14 miRNAs were specifically detected in XX ovary, XY testis, and YY testis, respectively. We observed relative lower expression of several miR-200 family members, including miR-141 and miR-429 in YY testis compared with XY testis. Histological analysis indicated a higher degree of testis maturity in YY super-males compared with XY males, as shown by larger spermatogenic cyst, more spermatids and fewer spermatocytes in the spermatogenic cyst. Moreover, five miR-200 family members were significantly up-regulated in testis when treated by 17α-ethinylestradiol (EE2), high dose of which will impair testis development and cell proliferation. The down-regulation of miR-141 and 429 coincides with the progression of testis development in both yellow catfish and human. At last, the expression pattern of nine arbitrarily selected miRNAs detected by quantitative RT-PCR was consistent with the Solexa sequencing results. Our study provides a comprehensive miRNA transcriptome analysis for gonad of yellow catfish with different sex genotypes, and identifies a number of sex-biased miRNAs, some of that are potentially involved in testis development and spermatogenesis.