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Sex determination in animals is not only determined by karyotype but can also be modulated by environmental cues like temperature via unclear transduction mechanisms. Moreover, in contrast to earlier views that sex may exclusively be determined by either karyotype or temperature, recent observations suggest that these factors rather co-regulate sex, posing another mechanistic mystery. Here, we discovered that certain wild-isolated and mutant C. elegans strains displayed genotypic germline sex determination (GGSD), but with a temperature-override mechanism. Further, we found that BiP, an ER chaperone, transduces temperature information into a germline sex-governing signal, thereby enabling the coexistence of GGSD and temperature-dependent germline sex determination (TGSD). At the molecular level, increased ER protein-folding requirements upon increased temperatures lead to BiP sequestration, resulting in ERAD-dependent degradation of the oocyte fate-driving factor, TRA-2, thus promoting male germline fate. Remarkably, experimentally manipulating BiP or TRA-2 expression allows to switch between GGSD and TGSD. Physiologically, TGSD allows C. elegans hermaphrodites to maintain brood size at warmer temperatures. Moreover, BiP can also influence germline sex determination in a different, non-hermaphroditic nematode species. Collectively, our findings identify thermosensitive BiP as a conserved temperature sensor in TGSD, and provide mechanistic insights into the transition between GGSD and TGSD. Synopsis: Temperature has long been known to modulate sex in various animals, but the mechanism for transducing temperature into a sex reversal signal is still a mystery. This work identifies BiP as a sensor that translates ambient temperature cues into the germline sex determination signal in C. elegans. Genotypic germline sex determination (GGSD) in wild-isolated and mutant C. elegans strains can be overridden by temperature changes. BiP sequestration for increased ER protein folding burden upon temperature elevation causes ERAD-mediated downregulation of the oocyte fate-driving factor, TRA-2. BiP's role in germline sex determination is conserved in a dioecious nematode species. Manipulation of BiP-dependent transduction allows switching between GGSD and temperature-dependent germline sex determination (TGSD). TGSD facilitates brood size maintenance in C. elegans hermaphrodites at elevated temperatures. Masculinization of the C. elegans germline in response to temperature elevation is mediated by BiP, which can override genotypic sex determination. [ABSTRACT FROM AUTHOR]

Background: Blotched snakehead (Channa maculata) displays significant sexual dimorphism, with males exhibiting faster growth rates and larger body sizes compared to females. The cultivation of the all-male population of snakeheads holds substantial economic and ecological value. Nonetheless, the intricate processes governing the development of bipotential gonads into either testis or ovary in C. maculata remain inadequately elucidated. Therefore, it is necessary to determine the critical time window of sex differentiation in C. maculata, providing a theoretical basis for sex control in production practices. Methods: The body length and weight of male and female C. maculata were measured at different developmental stages to reveal when sexual dimorphism in growth initially appears. Histological observations and spatiotemporal comparative transcriptome analyses were performed on ovaries and testes across various developmental stages to determine the crucial time windows for sex differentiation in each sex and the sex-related genes. Additionally, qPCR and MG2C were utilized to validate and locate sex-related genes, and levels of E2 and T were quantified to understand sex steroid synthesis. Results: Sexual dimorphism in growth became evident starting from 90 dpf. Histological observations revealed that morphological sex differentiation in females and males occurred between 20 and 25 dpf or earlier and 30–35 dpf or earlier, respectively, corresponding to the appearance of the ovarian cavity or efferent duct anlage. Transcriptome analyses revealed divergent gene expression patterns in testes and ovaries after 30 dpf. The periods of 40–60 dpf and 60–90 dpf marked the initiation of molecular sex differentiation in females and males, respectively. Male-biased genes (Sox11a, Dmrt1, Amh, Amhr2, Gsdf, Ar, Cyp17a2) likely play crucial roles in male sex differentiation and spermatogenesis, while female-biased genes (Foxl2, Cyp19a1a, Bmp15, Figla, Er) could be pivotal in ovarian differentiation and development. Numerous biological pathways linked to sex differentiation and gametogenesis were also identified. Additionally, E2 and T exhibited sexual dimorphism during sex differentiation and gonadal development. Based on these results, it is hypothesized that in C. maculata, the potential male sex differentiation pathway, Sox11a–Dmrt1–Sox9b, activates downstream sex-related genes (Amh, Amhr2, Gsdf, Ar, Cyp17a2) for testicular development, while the antagonistic pathway, Foxl2/Cyp19a1a, activates downstream sex-related genes (Bmp15, Figla, Er) for ovarian development. Conclusions: This study provides a comprehensive overview of gonadal dynamic changes during sex differentiation and gametogenesis in C. maculata, establishing a scientific foundation for sex control in this species. Plain language summary: Blotched snakehead (Channa maculata) exhibits significant sexual dimorphism, as males display faster growth rates and larger body sizes compared to females. The cultivation of the all-male population of snakeheads holds substantial economic and ecological value. However, the mechanisms underlying sex determination and differentiation in C. maculata remain insufficiently elucidated. In this study, sexual dimorphism in growth became evident starting from 90 dpf through the measurement of body length and weight of male and female C. maculata at different developmental stages. Histological observations indicated that morphological sex differentiation in females and males occurred at 20–25 dpf or earlier and 30–35 dpf or earlier, respectively, corresponding to the appearance of the ovarian cavity or efferent duct anlage. Transcriptome analyses revealed divergent gene expression patterns in male and female gonads after 30 dpf, suggesting that the period preceding 30 dpf might be the critical time window for sex control in C. maculata. The periods of 40–60 dpf and 60–90 dpf marked the initiation of molecular sex differentiation in females and males, respectively. Male-biased genes (Sox11a, Dmrt1, Amh, Amhr2, Gsdf, Ar, Cyp17a2) likely play crucial roles in testicular differentiation and spermatogenesis, while female-biased genes (Foxl2, Cyp19a1a, Bmp15, Figla, Er) could be pivotal in ovarian differentiation and oogenesis. Additionally, numerous biological pathways linked to sex differentiation and gametogenesis were identified. Moreover, sexual dimorphism was observed in the levels of E2 and T during gonadal differentiation and development. Based on these findings, it is hypothesized that in C. maculata, the potential male sex differentiation pathway, Sox11a–Dmrt1–Sox9b, activates downstream sex-related genes (Amh, Amhr2, Gsdf, Ar, Cyp17a2) for testicular development, while the antagonistic pathway, Foxl2/Cyp19a1a, activates downstream sex-related genes (Bmp15, Figla, Er) for ovarian development. This study provides a comprehensive overview of gonadal dynamic changes during sex differentiation and gametogenesis in C. maculata, thereby establishing a scientific foundation for sex control in this species. Highlights: Sexual dimorphism in growth became apparent starting from 90 dpf. The morphological differentiation of ovary and testis occurred at 20–25 dpf or earlier and 30–35 dpf or earlier, respectively, and the period preceding 30 dpf may be the critical time for sex control in C. maculata. Male-biased genes (Sox11a, Dmrt1, Amh, Amhr2, Gsdf, Ar, Cyp17a2) likely play crucial roles in testicular differentiation and spermatogenesis, whereas female-biased genes (Foxl2, Cyp19a1a, Bmp15, Figla, Er) could be pivotal in ovarian differentiation and oogenesis. The fate of undifferentiated primordial gonads in C. maculata may be determined by the antagonistic action of the Sox11a–Dmrt1–Sox9b and Foxl2/Cyp19a1a pathways. [ABSTRACT FROM AUTHOR]

The sex determination system of largemouth bass (Micropterus salmoides, LMB) is XX/XY; however, the underlying molecular mechanisms involved in early sex differentiation, gonadal development, and exogenous hormone-induced sex reversal remain unknown. In this study, LMB at 15 days post-hatching (dph) were fed diets containing 20 mg/kg of 17a-methyltestosterone (17a-MT) or 30 mg/kg of 17ß-estradiol (17ß-E2) for 60 days, respectively. Serum steroid levels, histological observations of the gonads, and identification of sex-specific markers were employed to screen the gonads of 60-day-old normal female fish (XX-F), normal male fish (XY-M), 17ß-E2 induced pseudo-female fish (XY-F), and 17a-MT-induced pseudo-male fish (XX-M) for transcriptome sequencing in order to uncover genes and pathway involved in the process of sexual reversal. The results from histology and serum sex steroid hormone analysis showed that both 17a-MT and 17ß-E2 were capable of inducing sex reversal of LMB at 15 dph. Transcriptome results revealed a total of 2,753 genes exhibiting differential expression, and the expression pattern of these genes in the gonads of XX-M or XY-F resembled that of normal females or males. The male sex-biased genes that are upregulated in XX-M and downregulated in XY-F are referred to as key genes for male reversal, while the female sex-biased genes that are upregulated in XY-F and downregulated in XX-M are referred to as key genes for female reversal. Finally, 12 differentially expressed genes (DEGs) related to male sex reversal were screened, including star2, cyp17a, cyp11b1, dmrt1, amh, sox9a, katnal1, spata4, spata6l, spata7, spata18 and foxl3. 2DEGs (foxl2a and cyp19a1b) were found to be associated with female sex reversal. The changes in these genes collectively influence the direction of sex differentiation of LMB. Among them, star2, dmrt1 and cyp19a1b with significantly altered expression levels may play potentially crucial role in the process of gender reversal. The expression patterns of 21 randomly selected genes were verified using qRT-PCR which confirmed the reliability and accuracy of the RNA-seq results. These findings not only enhance our understanding of the molecular basis underlying sex reversal but also provide crucial data support for future breeding research on unisexual LMB. [ABSTRACT FROM AUTHOR]

Introduction: Endosymbiotic bacteria in the genus Wolbachia have evolved numerous strategies for manipulating host reproduction in order to promote their own transmission. This includes the feminization of males into functional females, a well-studied phenotype in the isopod Armadillidium vulgare. Despite an early description of this phenotype in isopods and the development of an evolutionary model of host sex determination in the presence of Wolbachia, the underlying genetic mechanisms remain elusive. Methods: Here we present the first complete genomes of the three feminizing Wolbachia (wVulC, wVulP, and wVulM) known to date in A. vulgare. These genomes, belonging to Wolbachia B supergroup, contain a large number of mobile elements such as WO prophages with eukaryotic association modules. Taking advantage of these data and those of another Wolbachia-derived feminizing factor integrated into the host genome (f element), we used a comparative genomics approach to identify putative feminizing factors. Results: This strategy has enabled us to identify three prophage-associated genes secreted by the Type IV Secretion System: one ankyrin repeat domaincontaining protein, one helix-turn-helix transcriptional regulator and one hypothetical protein. In addition, a latrotoxin-related protein, associated with phage relic genes, was shared by all three genomes and the f element. Conclusion: These putative feminization-inducing proteins shared canonical interaction features with eukaryotic proteins. These results pave the way for further research into the underlying functional interactions. [ABSTRACT FROM AUTHOR]

In organisms with the XY sex-determination system, there is an imbalance in the inheritance and transmission of the X chromosome between males and females. Unlike an autosomal allele, an X-linked recessive allele in a female will have phenotypic effects on its male counterpart. Thus, genes located on the X chromosome are of particular interest to researchers in molecular evolution and genetics. Here we present a model for selection with two alleles of X-linkage to understand fitness components associated with genes on the X chromosome. We apply this model to the fitness analysis of an X-linked gene, OdsH (16D), in the fruit fly Drosophila melanogaster. The function of OdsH is involved in sperm production and the gene is rapidly evolving under positive selection. Using site-directed gene targeting, we generated functional and defective OdsH variants tagged with the eye-color marker gene white. We compare the allele frequency changes of the two OdsH variants, each directly competing against a wild-type OdsH allele in concurrent but separate experimental populations. After 20 generations, the two genetically modified OdsH variants displayed a 40% difference in allele frequencies, with the functional OdsH variant demonstrating an advantage over the defective variant. Using maximum likelihood estimation, we determined the fitness components associated with the OdsH alleles in males and females. Our analysis revealed functional aspects of the fitness determinants associated with OdsH , and that sex-specific fertility and viability consequences both contribute to selection on an X-linked gene. [ABSTRACT FROM AUTHOR]

Aquaculture, the world's fastest-growing food production sector, is critical for addressing food security concerns because of its potential to deliver high-quality, nutrient-rich supplies by 2050. This review assesses the effectiveness of CRISPR/Cas9 genome editing technology in enhancing desirable traits in fish species, including growth rates, muscle quality, disease resistance, pigmentation, and more. It also focuses on the potential effectiveness of the technology in allowing precise and targeted modifications of fish DNA to improve desirable characteristics. Many studies have reported successful applications of CRISPR/Cas9, such as knocking out reproductive genes to control reproduction and sex determination, enhancing feed conversion efficiency, and reducing off-target effects. Additionally, this technology has contributed to environmental sustainability by reducing nitrogen-rich waste and improving the nutritional composition of fish. However, the acceptance of CRISPR/Cas9 modified fish by the public and consumers is hindered by concerns regarding public perception, potential ecological impacts, and regulatory frameworks. To gain public approval and consumer confidence, clear communication about the editing process, as well as data on the safety and environmental considerations of genetically modified fish, are essential. This review paper discusses these challenges, provides possible solutions, and recommends future research on the integration of CRISPR/Cas9 into sustainable aquaculture practices, focusing on the responsible management of genetically modified fish to enable the creation of growth and disease-resistant strains. In conclusion, this review highlights the transformative potential of CRISPR/Cas9 technology in improving fish traits, while also considering the challenges and ethical considerations associated with sustainable and responsible practices in aquaculture. [ABSTRACT FROM AUTHOR]

Background: The knowledge about the anatomy of the mandible and its variations in age, sex and race will help physicians, surgeons, medico -legal authorities and anthropologists to give correct interpretations for the diagnostic procedures in living. Aim and objective: To study the Sex determination & morphometric parameters of human mandible. Material and method: We collected the human mandible bones (N=122) from the department of Anatomy, Index Medical College Hospital & Research Centre, Indore. region to study the morphological and morphometric features.Results: Among all parameters Six dominating parameters that possibly explain the nature of the mandible are height of the ramus, body thickness, anthropometric arch width, inter incisor width, mandibular index and mandibular angle are useful to determine the unknown sex of the mandible upto an extent of 75.2% in south Indian population. The incidence of the above mentioned sex determination parameters considered together and treated statistically. Conclusion: The present study reveals that the mandible of unknown gender can be sexed to the extent of 75% accuracy by six dominating parameters and not to consider these for complete sex determination of the mandible bone in osteometric studies. [ABSTRACT FROM AUTHOR]

The Eurasian Eagle-Owl (Bubo bubo) shows reversed sexual size dimorphism. We aimed to evaluate morphological size differences between the sexes of the smallest eagle-owl subspecies (B. b. kiautschensis), for which little morphometric information is available, and to develop a discriminant function for sex using a minimum number of morphometric parameters. We compared nine morphological measurements of 41 genetically or anatomically sexed eagle-owls admitted to a Korean wildlife rescue center and used discriminant function analysis of 29 birds (17 female, 12 male) with complete measurement data of nine biometrics. We developed four equations using three measurements (total length, head length, and weight) that had 86–96% accuracy for sexing Korean Eagle-Owls. The subspecies-specific morphometric data and discriminant functions we developed can help fill the current knowledge gap regarding the morphological characteristics of this little-known subspecies, benefiting researchers, wildlife managers, and veterinarians who work with or study this apex predator in the Korean forest ecosystem. [ABSTRACT FROM AUTHOR]

Key message: Presented here are model Yang cycle, ethylene biosynthesis and signaling pathways in Cannabis sativa. C. sativa floral transcriptomes were used to predict putative ethylene-related genes involved in sexual plasticity in the species. Sexual plasticity is a phenomenon, wherein organisms possess the ability to alter their phenotypic sex in response to environmental and physiological stimuli, without modifying their sex chromosomes. Cannabis sativa L., a medically valuable plant species, exhibits sexual plasticity when subjected to specific chemicals that influence ethylene biosynthesis and signaling. Nevertheless, the precise contribution of ethylene-related genes (ERGs) to sexual plasticity in cannabis remains unexplored. The current study employed Arabidopsis thaliana L. as a model organism to conduct gene orthology analysis and reconstruct the Yang Cycle, ethylene biosynthesis, and ethylene signaling pathways in C. sativa. Additionally, two transcriptomic datasets comprising male, female, and chemically induced male flowers were examined to identify expression patterns in ERGs associated with sexual determination and sexual plasticity. These ERGs involved in sexual plasticity were categorized into two distinct expression patterns: floral organ concordant (FOC) and unique (uERG). Furthermore, a third expression pattern, termed karyotype concordant (KC) expression, was proposed, which plays a role in sex determination. The study revealed that CsERGs associated with sexual plasticity are dispersed throughout the genome and are not limited to the sex chromosomes, indicating a widespread regulation of sexual plasticity in C. sativa. [ABSTRACT FROM AUTHOR]

• For the first time PCR was used to determine the sex in the genus Encephalartos (Zamiaceae). • Sex determination makers were used to identify sex potential sex change events occurring in cycads. • The use sex determination markers for Encephalartos greatly benefits ex situ conservation of the genus. Species within Encephalartos Lehm., the largest cycad genus in Africa, face considerable threats from habitat loss and illegal collection. Living collections in botanical gardens play a crucial role in conserving these slow-growing plants, necessitating the presence of both male (microsporangiate) and female (megasporangiate) individuals for successful sexual reproduction. Recent genomic research has identified sex-specific genes in cycads, offering an opportunity for sex determination in ex situ collections. This study tested the utility of the CYCAS_034085 gene, found exclusively in microsporangiate plants, for identifying the sex of Encephalartos individuals using a simple qualitative PCR assay. A total of 88 accessions representing six Encephalartos species were collected from Kirstenbosch National Botanical Garden. The results demonstrated that the developed primer combination effectively differentiated between microsporangiate and megasporangiate plants, achieving an accuracy of 86.3 %. This PCR-based sex determination method represents a valuable tool for cycad conservation management and the establishment of effective ex situ collections. [ABSTRACT FROM AUTHOR]

Background: Small for gestational age (SGA) and large for gestational age (LGA) are designations given to neonates based solely on birthweight, with no distinction made for maternal height. However, there is a possibility that maternal height is significantly correlated with neonatal birthweight, and if so, SGA and LGA cutoffs specific to maternal height may be a more precise and useful tool for clinicians. To explore this possibility, we analyzed the association between maternal height and ethnicity and neonate birthweight in women with low‐risk, 37‐ to 40‐week gestation, singleton pregnancies who gave birth vaginally between 2010 and 2017 (n = 354,488). For this retrospective cohort study, we used electronic obstetric records obtained from the National Obstetrics Registry in Malaysia. Methods: National Obstetric Registry (NOR) data were used to calculate the 10th and 90th birthweight percentiles for each maternal height group by gestational age and neonatal sex. Multiple linear regression models, adjusted for maternal age, weight, parity, gestational age, and neonatal sex, were used to examine the association between neonate birthweight and maternal ethnicity and height. The following main outcome measures were assessed: small for gestational age (<10th percentile), large for gestational age (>90th percentile), and birthweight. Results: The median height was 155 cm (IQR, 152–159), with mothers of Chinese descent being the tallest (median (IQR): 158 cm (154–162)) and mothers of Orang Asli (Indigenous) descent the shortest (median (IQR): 151 cm (147–155)). The median birthweight was 3000 g (IQR, 2740–3250), with mothers of Malay and Chinese ethnicity and Others having, on average, the heaviest babies, followed by other Bumiputeras (indigenous) mothers, mothers of Indian ethnicity, and lastly, mothers of Orang Asli ethnicity. For infants, maternal age, height, weight, parity, male sex, and gestational age were positively associated with birthweight. Maternal height had a positive association with neonate birthweight (B = 7.08, 95% CI: 6.85–7.31). For ethnicity, compared with neonates of Malay ethnicity, neonates of Chinese, Indian, Orang Asli, and other Bumiputera ethnicities had lower birthweights. Conclusion: Birthweight increases with maternal height among Malaysians of all ethnicities. SGA and LGA cutoffs specific to maternal height may be useful to guide pregnancy management. [ABSTRACT FROM AUTHOR]

Our understanding of the molecular pathways that regulate oogenesis and define cellular identity in the Arthropod female reproductive system and the extent of their conservation is currently very limited. This is due to the focus on model systems, including Drosophila and Daphnia, which do not reflect the observed diversity of morphologies, reproductive modes, and sex chromosome systems. We use single-nucleus RNA and ATAC sequencing to produce a comprehensive single nucleus atlas of the adult Artemia franciscana female reproductive system. We map our data to the Fly Cell Atlas single-nucleus dataset of the Drosophila melanogaster ovary, shedding light on the conserved regulatory programs between the two distantly related Arthropod species. We identify the major cell types known to be present in the Artemia ovary, including germ cells, follicle cells, and ovarian muscle cells. Additionally, we use the germ cells to explore gene regulation and expression of the Z chromosome during meiosis, highlighting its unique regulatory dynamics and allowing us to explore the presence of meiotic sex chromosome silencing in this group. Author summary: Oogenesis is a highly complex process involving multiple cell-types and an extremely orchestrated program that unfolds in the female reproductive system. Despite the extreme diversity of Arthropod reproductive modes and sex determination systems, our current understanding of oogenesis is limited to a few model species. This makes it difficult to study and formulate hypotheses about the evolutionary history, constraints, and importance of the individual elements of this process. To fill this gap, we used single-nucleus expression and chromatin-accessibility data to produce a single-nucleus atlas of the Artemia franciscana female reproductive system. By comparing our dataset to the published Drosophila single-nucleus data (over 400 million years of divergence), we were able to highlight the extreme conservation of several of the molecular pathways of oogenesis and meiosis. We found evidence of global transcriptional quiescence and chromatin condensation in late germ cells, highlighting the conserved role of this repressive stage in arthropod oogenesis. Additionally, we explored the expression patterns of the ZW sex chromosomes during oogenesis. Our data shows that the Z-chromosome is consistently downregulated in germline cells. While this is partly driven by a lack of dosage compensation in the germline, a subset of cells show stronger repression of the Z chromosome. [ABSTRACT FROM AUTHOR]

Advances in genome sequencing have greatly accelerated the identification of sex chromosomes in a variety of species. Many of these species have experienced structural rearrangements that reduce recombination between the sex chromosomes, allowing the accumulation of sequence differences over many megabases. Identification of the genes that are responsible for sex determination within these sometimes large regions has proved difficult. Here, we identify an XY sex chromosome system on LG19 in the West African cichlid fish Chromidotilapia guntheri in which the region of differentiation extends over less than 400 kb. We develop high-quality male and female genome assemblies for this species, which confirm the absence of structural variants, and which facilitate the annotation of genes in the region. The peak of differentiation lies within rin3, which has experienced several debilitating mutations on the Y chromosome. We suggest two hypotheses about how these mutations might disrupt endocytosis, leading to Mendelian effects on sexual development. [ABSTRACT FROM AUTHOR]

Haldane’s rule occupies a special place in biology as one of the few ‘rules’ of speciation, with empirical support from hundreds of species. And yet, its classic purview is restricted taxonomically to the subset of organisms with heteromorphic sex chromosomes. I propose explicit acknowledgement of generalized hypotheses about Haldane’s rule that frame sex bias in hybrid dysfunction broadly and irrespective of the sexual system. The consensus view of classic Haldane’s rule holds that sex-biased hybrid dysfunction across taxa is a composite phenomenon that requires explanations from multiple causes. Testing of the multiple alternative hypotheses for Haldane’s rule is, in many cases, applicable to taxa with homomorphic sex chromosomes, environmental sex determination, haplodiploidy, and hermaphroditism. Integration of a variety of biological phenomena about hybrids across diverse sexual systems, beyond classic Haldane’s rule, will help to derive a more general understanding of the contributing forces and mechanisms that lead to predictable sex biases in evolutionary divergence and speciation. [ABSTRACT FROM AUTHOR]

Waprin, a WAP (Whey acidic protein) domain‐containing extracellular secretory protein, is widely known for its antibacterial properties. In this study, a waprin homologue (Tc_wapF) expressing in a female‐specific manner was identified in Tribolium castaneum, through the analysis of sex‐specific transcriptomes. Developmental‐ and tissue‐specific profiling revealed the widespread expression of Tc_wapF in adult female tissues, particularly in the ovary, gut and fatbody. This female‐specific expression of Tc_wapF is not regulated by the classical sex‐determination cascade of T. castaneum, as we fail to get any attenuation in Tc_wapF transcript levels in Tcdsx and Tctra (key players of sex determination cascade of T. castaneum) knockdown females. RNA interference‐mediated knockdown of Tc_wapF in females led to the non‐hatching of eggs laid by these females, suggesting the crucial role of Tc_wapF in the embryonic development in T. castaneum. This is the first report on the identification of a sex‐specific waprin homologue in an insect and its involvement in embryonic development. Future investigations on the functional conservation of insect waprins and their mechanistic role in embryonic development can be exploited for improving pest management strategies. [ABSTRACT FROM AUTHOR]

Background. This study aims to evaluate the accuracy rate of foramen magnum dimensions in determining sex among the South Indian population using discriminant functional analysis. Methods. An observational study in which CBCT images from 200 full field of view (FOV) scans were analysed. The dimensions of the foramen magnum were measured. Intra‐ and interobserver reliability were calculated. Independent t‐tests were used to compare the various parameters between sexes. Stepwise discriminant function analysis was used to determine sex. Results. A total of 200 CBCT scans were included in the study. The mean age (±SD) was 25.66 (±7.11) years among males and 24.64 (±5.12) years among females. The measurements and the circumference of the foramen magnum were significantly (p < 0.001) greater in males than in females. The univariate analysis of foramen magnum measurements reached an accuracy rate of 73.5% in sex determination. The discriminant function analysis combining the foramen magnum measurements and circumference yielded an overall predictability rate of 66.5% for determining sex. Conclusion. Taking into account the predictability rate of sex based on foramen measurement in the present population, it can be concluded that its applicability should be limited to cases associated with fragmentary skull bases. [ABSTRACT FROM AUTHOR]

Lunar rhythms shape spawning phenology and subsequent risks and rewards for early life-history stages in the sea. Here, we consider a perplexing spawning phenology of the sixbar wrasse (Thalassoma hardwicke), in which parents spawn disproportionately around the new moon, despite the low survival of these larvae. Because primary sex determination in this system is highly plastic and sensitive to social environments experienced early in development, we ask whether this puzzling pattern of spawning is explained by fitness trade-offs associated with primary sexual maturation. We used otoliths from 871 fish to explore how spawning on different phases of the moon shapes the environments and phenotypes of settling larvae. Offspring that were born at the new moon were more likely to settle (i) before other larvae, (ii) at a larger body size, (iii) at an older age, (iv) to the best quality sites, and (v) as part of a social group—all increasing the likelihood of primary maturation to male. Selection of birthdates across life stage transitions suggests that the perplexing spawning phenology of adults may reflect an evolutionarily stable strategy that includes new moon spawning for compensatory benefits later in life, including preferential production of primary males at certain times. [ABSTRACT FROM AUTHOR]

Simple Summary: The great cormorant has become a model taxon in the study of the ecology and ecotoxicology of fish-eating species. In this study, we used 157 adult and 222 juvenile dead individuals sexed by dissection to provide a method of sexing this species using external measurements. Males were larger than females in all linear body measurements, but there were no significant differences between adults and juveniles. Thus, in further analyses data on juveniles and adults within a sex was combined. The discriminant equations provided, with wing length and bill length, provided high accuracy, with 6.2% of individuals misclassified. The method presented here makes it possible to account for sex-specific patterns in ecological studies of the great cormorant and may be applied to data collected in the past. The possibility of sex identification of birds has substantial importance for studies on different aspects of bird ecology and behaviour. Using discriminant functions is becoming increasingly popular in studies of bird species that are monomorphic in plumage characteristics because they are cheap, hardly invasive and may be applied to data collected in the past. In this paper, we provide a discriminant function to sex great cormorants using external measurements. Males were larger than females in all linear body measurements, but there were no significant differences between adults and juveniles. Thus, data on juveniles and adults within a sex was combined. Discriminant equations with the most commonly used linear measurements, wing length and bill length, were provided. If identifying birds with discriminant function values D2 < −1.256 as females and those with D2 > 0.916 as males, 99% of birds will be correctly sexed. The method presented here makes it possible to account for sex-specific patterns in ecological studies of the great cormorant and may be applied to data collected in the past. The cross-application of discriminant functions developed for other populations of the great cormorant produces a 5.4% and 7.5% misclassification rate for birds from northern Poland using discriminant equations developed for populations in Greece and the Netherlands, respectively. [ABSTRACT FROM AUTHOR]

Background: Early identification of fetal gender is crucial for managing gender-linked genetic disorders. This study aimed to evaluate the predictive performance of anogenital distance (AGD) and genital tubercle angle (GTA) for fetal sex determination during the first trimester. Methods: A multicenter retrospective cohort study was conducted on 312 fetal cases between 11 and 13 + 6 weeks of gestation from two tertiary hospitals. AGD and GTA measurements were taken from midsagittal plane images using ultrasound, with intra- and inter-reader reproducibility assessed. Binomial logistic regression and ROC curve analysis were employed to determine the diagnostic performance and optimal cutoff points. Results: AGD had a mean of 7.16 mm in male fetuses and 4.42 mm in female fetuses, with a sensitivity of 88.8%, specificity of 94.4%, and an area under the ROC curve (AUC) of 0.931 (95% CI: 0.899–0.962) using 5.74 mm as a cutoff point. For GTA, the mean was 35.90 degrees in males and 21.57 degrees in females, with a sensitivity of 92%, specificity of 84.7%, and an AUC of 0.932 (95% CI: 0.904–0.961) using 28.32 degrees as a cutoff point. The reproducibility results were excellent for AGD (intra-operator ICC = 0.938, inter-operator ICC = 0.871) and moderate for GTA (intra-operator ICC = 0.895, inter-operator ICC = 0.695). Conclusions: The findings suggest that AGD and GTA are reliable markers for early fetal sex determination, with AGD showing higher reproducibility. The findings highlight the feasibility and accuracy of these non-invasive sonographic markers and their potential usefulness in guiding timely interventions and enhancing the management of gender-linked genetic conditions. [ABSTRACT FROM AUTHOR]

Sex determination in the nematode C. elegans is controlled by the master regulator XOL-1 during embryogenesis. Expression of xol-1 is dependent on the ratio of X chromosomes and autosomes, which differs between XX hermaphrodites and XO males. In males, xol-1 is highly expressed and in hermaphrodites, xol-1 is expressed at very low levels. XOL-1 activity is known to be critical for the proper development of C. elegans males, but its low expression was considered to be of minimal importance in the development of hermaphrodite embryos. Our study reveals that XOL-1 plays an important role as a regulator of developmental timing during hermaphrodite embryogenesis. Using a combination of imaging and bioinformatics techniques, we found that hermaphrodite embryos have an accelerated rate of cell division, as well as a more developmentally advanced transcriptional program when xol-1 is lost. Further analyses reveal that XOL-1 is responsible for regulating the timing of initiation of dosage compensation on the X chromosomes, and the appropriate expression of sex-biased transcriptional programs in hermaphrodites. We found that xol-1 mutant embryos overexpress the H3K9 methyltransferase MET-2 and have an altered H3K9me landscape. Some of these effects of the loss of xol-1 gene were reversed by the loss of met-2. These findings demonstrate that XOL-1 plays an important role as a developmental regulator in embryos of both sexes, and that MET-2 acts as a downstream effector of XOL-1 activity in hermaphrodites. Author summary: Various organisms have differing ways of determining, at a molecular level, what the sex of a developing embryo is supposed to be. The two sexes in the nematode C. elegans, hermaphrodite and male, have different numbers of X chromosomes. Hermaphrodites have two X chromosomes and males only have one. This mismatch raises an additional problem as hermaphrodites will have twice the amount of genes expressed from the X compared to males. This is solved by a process called dosage compensation, which equalizes gene expression between the sexes. A molecular sensor called XOL-1 detects the number of X chromosomes in an embryo and kick-starts the process of proper sexual development and/or dosage compensation. XOL-1 was known to be very important for activating male development but was believed to not have any role in the development of the hermaphrodite sex. We show that XOL-1 has some crucial roles in hermaphrodite embryos in controlling the rate of development of the embryo, and regulating the timing of dosage compensation. We also show that MET-2, a protein that deposits repressive methyl marks on DNA-bound histone proteins, is involved in this process. [ABSTRACT FROM AUTHOR]

Population-scale genome modification can alter the composition or fate of wild populations. Synthetic gene drives provide one set of tools, but their use is complicated by scientific, regulatory, and social issues associated with transgene persistence and flow. Here we propose an alternative approach. An Allele Sail consists of a genome editor (the Wind) that introduces DNA sequence edits, and is inherited in a Mendelian fashion. Meanwhile, the edits (the Sail) experience an arithmetic, Super-Mendelian increase in frequency. We model this system and identify contexts in which a single, low frequency release of an editor brings edits to a very high frequency. We also identify conditions in which manipulation of sex determination can bring about population suppression. In regulatory frameworks that distinguish between transgenics (GMO) and their edited non-transgenic progeny (non-GMO) Allele Sails may prove useful since the spread and persistence of the GM component can be limited. Population-scale genome modification can alter the composition or fate of wild populations. Here the authors introduce Allele Sails as a method for spreading genetic changes throughout a population. [ABSTRACT FROM AUTHOR]

Bird sex determination is fundamental in various ecological and biological studies, although many avian species cannot be sexed visually due to their monomorphic and/or monochromatic appearance. Thus, reliable laboratory methods for sexing are a prerequisite. Most avian nestlings lack sex-related signs, including the Eurasian pygmy owl (Glaucidium passerinum). We performed laboratory sex determination analysis of this species using blood samples of 242 juveniles and nine adults. It relied on the qPCR of the specific intron from the chromo-helicase DNA-binding protein 1 gene. We tested three primer sets, the P2/P8, 2550F/2718R, and CHD1F/CHD1R, commonly used for bird laboratory sexing. The outcomes were displayed on an agarose gel electrophoresis and a plot from melt curve analysis, which had not been previously conducted in Eurasian pygmy owls. We found that only primer set CHD1F/CHD1R proved reliable, as the only one determined sex with one and two band/s and peak/s on the electrophoresis and the melt curve plot for males and females, respectively. The other two primer pairs failed and depicted one band/peak in all specimens regardless of their sex. Therefore, we recommend performing Eurasian pygmy owls' laboratory sexing by qPCR with CHD1F/CHD1R primers only. [ABSTRACT FROM AUTHOR]

The strength of molecular interactions is characterized by their dissociation constants (KD). Only high-affinity interactions (KD ≤ 10−8 M) are extensively investigated and support binary on/off switches. However, such analyses have discounted the presence of low-affinity binders (KD > 10−5 M) in the cellular environment. We assess the potential influence of low-affinity binders on high-affinity interactions. By employing Gillespie stochastic simulations and continuous methods, we demonstrate that the presence of low-affinity binders can alter the kinetics and the steady state of high-affinity interactions. We refer to this effect as 'herd regulation' and have evaluated its possible impact in two different contexts including sex determination in Drosophila melanogaster and in signalling systems that employ molecular thresholds. We have also suggested experiments to validate herd regulation in vitro. We speculate that low-affinity binders are prevalent in biological contexts where the outcomes depend on molecular thresholds impacting homoeostatic regulation. [ABSTRACT FROM AUTHOR]

The human tongue has been long believed to be a window to provide important insights into a patient's health in medicine. The present study introduced a novel approach to predict patient age, gender, and weight inferences based on tongue images using pretrained deep convolutional neural networks (CNNs). Our results demonstrated that the deep CNN models (e.g., ResNeXt) trained on dorsal tongue images produced excellent results for age prediction with a Pearson correlation coefficient of 0.71 and a mean absolute error (MAE) of 8.5 years. We also obtained an excellent classification of gender, with a mean accuracy of 80% and an AUC (area under the receiver operating characteristic curve) of 88%. ResNeXt model also obtained a moderate level of accuracy for weight prediction, with a Pearson correlation coefficient of 0.39 and a MAE of 9.06 kg. These findings support our hypothesis that the human tongue contains crucial information about a patient. This study demonstrated the feasibility of using the pretrained deep CNNs along with a large tongue image dataset to develop computational models to predict patient medical conditions for noninvasive, convenient, and inexpensive patient health monitoring and diagnosis. [ABSTRACT FROM AUTHOR]

The non-Mendelian transmission of sex chromosomes during gametogenesis carries significant implications, influencing sex ratios and shaping evolutionary dynamics. Here we focus on known mechanisms that drive non-Mendelian inheritance of X chromosomes during spermatogenesis and their impact on population dynamics in species with different breeding systems. In Drosophila and mice, X-linked drivers targeting Y-bearing sperm for elimination or limiting their fitness, tend to confer unfavourable effects, prompting the evolution of suppressors to mitigate their impact. This leads to a complex ongoing evolutionary arms race to maintain an equal balance of males and females. However, in certain insects and nematodes with XX/X0 sex determination, the preferential production of X-bearing sperm through atypical meiosis yields wild-type populations with highly skewed sex ratios, suggesting non-Mendelian transmission of the X may offer selective advantages in these species. Indeed, models suggest X-meiotic drivers could bolster population size and persistence under certain conditions, challenging the conventional view of their detrimental effects. Furthering our understanding of the diverse mechanisms and evolutionary consequences of non-Mendelian transmission of X chromosomes will provide insights into genetic inheritance, sex determination, and population dynamics, with implications for fundamental research and practical applications. [ABSTRACT FROM AUTHOR]

Similar to most Psittaciformes, the blue-fronted parrot (Amazona aestiva) lacks sexual dimorphism. In this way, sexing methods have been investigated to assist in the reproductive management and medical care of these birds. This study aimed to assess head and radiographic biometry for sex identification of blue-fronted parrots. Six head measurements and 23 radiographic measurements of 52 carcasses (24 males and 28 females) were taken. Males exhibited higher mean values than females for most of the measurements. For head biometry, the proposed discriminant equation containing rhinotheca length and head plus rhinotheca length allowed for correct sexing of 60% of males and 88% of females, while for radiographic biometry the discriminant equation containing head heigh and right alula length allowed the discrimination of 84.6% of males and 66.7% of females. This is the first study evaluating the use of radiographic biometry for sexing psittaciforms. Both biometric methods are suitable for sexing blue-fronted parrots when DNA sampling is not possible, since they are low-cost, provide immediate results, and are non-invasive techniques. [ABSTRACT FROM AUTHOR]

The equilibrium of sex ratios in sexually reproducing species is often disrupted by various environmental and genetic factors, including endosymbionts like Wolbachia. In this study, we explore the highly female‐biased sex ratio observed in the flea beetle, Altica lythri, and its underlying mechanisms. Ancient hybridization events between Altica species have led to mitochondrial DNA introgression, resulting in distinct mitochondrial haplotypes that go along with different Wolbachia infections (HT1‐wLytA1, HT1*‐ uninfected, HT2‐wLytA2, and HT3‐wLytB). Notably, beetles with some haplotypes exclusively produce female offspring, suggesting potential Wolbachia‐induced phenomena such as feminization of genetic males. However, the observed female bias could also be a consequence of the ancient hybridization resulting in nuclear–cytoplasmic conflicts between introgressed mtDNA and nuclear genes. Through transcriptomic analysis and the program SEX‐DETector, we established markers for genotypic sex differentiation for A. lythri, enabling genetic sexing via qPCR. Our findings suggest that feminization of genetic males is contributing to the skewed sex ratios, highlighting the intricate dynamics of sex determination and reproductive strategies in this flea beetle. This study provides valuable insights into the dynamics of genetic conflicts, endosymbionts, and sex ratios, revealing the novel phenomenon of genetic male feminization in the flea beetle A. lythri. [ABSTRACT FROM AUTHOR]

Changes in gene dosage can have tremendous evolutionary potential (e.g. whole-genome duplications), but without compensatory mechanisms, they can also lead to gene dysregulation and pathologies. Sex chromosomes are a paradigmatic example of naturally occurring gene dosage differences and their compensation. In species with chromosome-based sex determination, individuals within the same population necessarily show 'natural' differences in gene dosage for the sex chromosomes. In this Review, we focus on the mammalian X chromosome and discuss recent new insights into the dosage-compensation mechanisms that evolved along with the emergence of sex chromosomes, namely X-inactivation and X-upregulation. We also discuss the evolution of the genetic loci and molecular players involved, as well as the regulatory diversity and potentially different requirements for dosage compensation across mammalian species. [ABSTRACT FROM AUTHOR]

Genes on the Y chromosome play important roles in male sex determination and development. The identification of Y‐chromosome‐specific genes not only provides a theoretical basis for the study of male reproductive development, but also offers genetic control targets for agricultural pests. However, Y‐chromosome genes are rarely characterized due to their high repeatability and high heterochromatinization, especially in the oriental fruit fly. In this study, 1 011 Y‐chromosome‐specific candidate sequences were screened from 2 to 4 h Bactrocera dorsalis embryo datasets with the chromosome quotient method, 6 of which were identified as Y‐chromosome‐specific sequences by polymerase chain reaction, including typo‐gyf, a 19 126‐bp DNA sequence containing a 575‐amino acid open reading frame. Testicular deformation and a significant reduction in sperm number were observed after typo‐gyf knockdown with RNA interference in embryos. After typo‐gyf knockout with clustered regularly interspaced palindromic repeats (CRISPR) / CRISPR‐associated protein 9 in the embryonic stage, the sex ratio of the emergent adults was unbalanced, with far more females than males. A genotype analysis of these females with the Y‐chromosome gene MoY revealed no sex reversal. Typo‐gyf knockout led to the death of XY individuals in the embryonic stage. We conclude that typo‐gyf is an essential gene for male survival, and is also involved in testicular development and spermatogenesis. The identification of typo‐gyf and its functional verification provide insight into the roles of Y‐chromosome genes in male development. [ABSTRACT FROM AUTHOR]

Populus tomentosa, an indigenous tree species, is widely distributed and cultivated over 1,000,000 km2 in China, contributing significantly to forest production, ecological conservation and urban–rural greening. Although a reference genome is available for P. tomentosa, the intricate interspecific hybrid origins, chromosome structural variations (SVs) and sex determination mechanisms remain confusion and unclear due to its broad and even overlapping geographical distribution, extensive morphological variations and cross infiltration among white poplar species. We conducted a haplotype‐resolved de novo assembly of P. tomentosa elite individual GM107, which comprises subgenomes a and b with a total genome size of 714.9 Mb. We then analysed the formation of hybrid species and the phylogenetic evolution and sex differentiation across the entire genus. Phylogenomic analyses suggested that GM107 likely originated from a hybridisation event between P. alba (♀) and P. davidiana (♂) approximately 3.8 Mya. A total of 1551 chromosome SVs were identified between the two subgenomes. More noteworthily, a distinctive inversion structure spanning 2.15–2.95 Mb was unveiled among Populus, Tacamahaca, Turaga, Aigeiros poplar species and Salix, highlighting a unique evolutionary feature. Intriguingly, a novel sex genotype of the ZY type, which represents a crossover between XY and ZW systems, was identified and confirmed through both natural and artificial hybrids populations. These novel insights offer significant theoretical value for the study of the species' evolutionary origins and serve as a valuable resource for ecological genetics and forest biotechnology. [ABSTRACT FROM AUTHOR]

Almost all species in the genus Salix (willow) are dioecious and willows have variable sex-determining systems, the role of this variation in maintaining species barriers is relatively untested. We first analyzed the sex determination systems (SDS) of two species, Salix cardiophylla and Salix interior , whose positions in the Salix phylogeny make them important for understanding a sex chromosome turnover that has been detected in their relatives, and that changed the system from male (XX/XY) to female (ZW/ZZ) heterogamety. We show that both species have male heterogamety, with sex-linked regions (SLRs) on chromosome 15 (termed a 15XY system). The SLRs occupy 21.3% and 22.8% of the entire reference chromosome, respectively. By constructing phylogenetic trees, we determined the phylogenetic positions of all the species with known SDSs. Reconstruction of ancestral SDS character states revealed that the 15XY system is likely the ancestral state in willows. Turnovers of 15XY to 15ZW and 15XY to 7XY likely contributed to early speciation in Salix and gave rise to major groups of the Vetrix and Salix clades. Finally, we tested introgression among species in the phylogenetic trees based on both autosomes and SLRs separately. Frequent introgression was observed among species with 15XY, 15ZW, and 7XY on autosomes, in contrast to the SLR datasets, which showed less introgression, and in particular no gene flow between 15ZW and 7XY species. We argue that, although SDS turnovers in willow speciation may not create complete reproductive barriers, the evolution of SLRs plays important roles in preventing introgression and maintaining species boundaries. [ABSTRACT FROM AUTHOR]

Simple Summary: Simple Summary: The genetics of sex determination in mammals has been studied mainly in humans and mice. However, some animals develop in other ways, like moles, whose females have mixed gonads that combine two parts: male (testes) and female (ovaries). In other animals and humans, such gonads are known but they are formed due to pathologies and disturb the ability to reproduce up to sterility. We first characterized the structural features of some genes and hypothesized that changes in the structure of the key gene for testis development Sry may be responsible for the ovotestes formation in European moles. Here, we considered the presence of the intron-containing fragments of the retroposon and presumably the existing copies of the Sry gene along with features of the placenta structure. Here, for the first time, the structure of genes involved in sex determination in mammals (full Sry and partial Rspo1, Eif2s3x, and Eif2s3y) was analyzed for the European mole Talpa europaea with ovotestes in females. We confirmed male-specificity for Eif2s3y and Sry. Five exons were revealed for Rspo1 and the deep similarity with the structure of this gene in T. occidentalis was proved. The most intriguing result was obtained for the Sry gene, which, in placental mammals, initiates male development. We described two exons for this canonically single-exon gene: the first (initial) exon is only 15 bp while the second exon includes 450 bp. The exons are divided by an extended intron of about 1894 bp, including the fragment of the LINE retroposon. Moreover, in chromatogram fragments, which correspond to intron and DNA areas, flanking both exons, we revealed double peaks, similar to heterozygous nucleotide sites of autosomal genes. This may indicate the existence of two or more copies of the Sry gene. Proof of copies requires an additional in-depth study. We hypothesize that unusual structure and possible supernumerary copies of Sry may be involved in ovotestes formation. [ABSTRACT FROM AUTHOR]

Recent advances in DNA sequencing technology have enabled the precise decoding of genomes in non-model organisms, providing a basis for unraveling the patterns and mechanisms of sex chromosome evolution. Studies of different species have yielded conflicting results regarding the traditional theory that sex chromosomes evolve from autosomes via the accumulation of deleterious mutations and degeneration of the Y (or W) chromosome. The concept of the 'sex chromosome cycle,' emerging from this context, posits that at any stage of the cycle (i.e. differentiation, degeneration, or loss), sex chromosome turnover can occur while maintaining stable sex determination. Thus, understanding the mechanisms that drive both the persistence and turnover of sex chromosomes at each stage of the cycle is crucial. In this review, we integrate recent findings on the mechanisms underlying maintenance and turnover, with a special focus on several organisms having unique sex chromosomes. Our review suggests that the diversity of sex chromosomes in the maintenance of stable sex determination is underappreciated and emphasizes the need for more research on the sex chromosome cycle. [ABSTRACT FROM AUTHOR]

Hemicentrotus pulcherrimus is an important commercial aquatic species. However, wild stocks have dramatically decreased in recent decades, and the gonads of H.pulcherrimus of different sexes showed significant differences in gonad index, gonad color, and flavour. Understanding the population genetic structure and sex-differentiation/determination mechanism can provide vital information for genetic conservation and improvement. In the present study, the SuperGBS method was used to identify genome-wide SNPs from a collection of 80 individuals consisting of four geographical populations covering the natural habitats of H. pulcherrimus in China seas. A total of 5785 high-quality SNPs were detected by using SuperGBS technology. The genetic diversity index showed that all populations had similar patterns with high Fis and low Ne, suggesting that it is necessary to carry out the conservation of H. pulcherrimus in China. Low genetic differentiation among the four geographical populations was detected by pairwise Fst, PCA, and admixture analysis. In addition, three sex-related SNPs located on three scaffolds were identified, suggesting a ZW-ZZ sex determination system in H. pulcherrimus. However, no sex-specific marker was identified in this study. Therefore, larger sample sizes and marker numbers need to be implemented to investigate the sex-associated markers and genes of H. pulcherrimus. In general, this study provides a molecular basis for population genetic structure and sex-differentiation/determination mechanism of H. pulcherrimus. [ABSTRACT FROM AUTHOR]

California halibut (Paralichthys californicus) is a candidate species for aquaculture and stock enhancement. These applications rely on sex control, either to maximize the production of faster growing females or to match sex ratios in the wild. Other paralichthids exhibit temperature‐dependent sex determination (TSD), but the presence and pattern of TSD is not well defined in California halibut. Juvenile California halibut were cultured at three distinct temperatures (15°C, 19°C, and 23°C) through the developmental period presumed to be thermosensitive based on findings from congeners. Sex ratios were quantified in each treatment using phenotypic sex identification techniques applied early (molecular biomarkers; 51–100 mm total length [TL]) and late (visual examination of the gonads; ≥100 mm TL) in the juvenile phase. Both techniques indicated similar sex determination trends at each temperature, with overall sex ratios assessed as 49.9% male at 15°C, 74.5% male at 19°C, and 98.2% male at 23°C. Growth rates were highest at 23°C and lowest at 15°C, with intrinsically fast‐ and slow‐growing individuals at all temperatures. At 15°C and 19°C, females comprised a higher proportion among the fast growers than they did among the slow growers. These data show that California halibut exhibit TSD, with temperatures of 19°C and 23°C masculinizing fish while 15°C appears to produce a 1:1 sex ratio. This study will help optimize sex ratios and growth in hatcheries through thermal manipulation. Furthermore, the developed biomolecular tools and identified temperature thresholds will be important in future work to understand the influence of global warming on wild population demographics. Research Highlights: California halibut exhibit temperature‐dependent sex determination.Rearing at 15°C produced an equal sex ratio, while exposure to higher temperatures (19°C and 23°C) caused masculinization.Expression of sex‐related genes (amh, cyp19a1a, foxl2) can be used to identify phenotypic sex. [ABSTRACT FROM AUTHOR]

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Sex chromosomes display remarkable diversity and variability among vertebrates. Compared with research on the X/Y and Z/W chromosomes, which have long evolutionary histories in mammals and birds, studies on the sex chromosomes at early evolutionary stages are limited. Here, we precisely assembled the genomes of homozygous XX female and YY male Lanzhou catfish (Silurus lanzhouensis) derived from an artificial gynogenetic family and a self-fertilized family, respectively. Chromosome 24 (Chr24) was identified as the sex chromosome based on resequencing data. Comparative analysis of the X and Y chromosomes showed an approximate 320 kb Y-specific region with a Y-specific duplicate of anti-Mullerian hormone type II receptor (amhr2y), which is consistent with findings in 2 other Silurus species but on different chromosomes (Chr24 of Silurus meridionalis and Chr5 of Silurus asotus). Deficiency of amhr2y resulted in male-to-female sex reversal, indicating that amhr2y plays a male-determining role in S. lanzhouensis. Phylogenetic analysis and comparative genomics revealed that the common sex-determining gene amhr2y was initially translocated to Chr24 of the Silurus ancestor along with the expansion of transposable elements. Chr24 was maintained as the sex chromosome in S. meridionalis and S. lanzhouensis , whereas a sex-determining region transition triggered sex chromosome turnover from Chr24 to Chr5 in S. asotus. Additionally, gene duplication, translocation, and degeneration were observed in the Y-specific regions of Silurus species. These findings present a clear case for the early evolutionary trajectory of sex chromosomes, including sex-determining gene origin, repeat sequence expansion, gene gathering and degeneration in sex-determining region, and sex chromosome turnover. [ABSTRACT FROM AUTHOR]

In this study, feces samples were collected from 7 individuals in Hainan gibbon (Nomascus hainanus) family group C by through non-invasive methods, and the levels of progesterone and testosterone were analyzed by high-performance liquid chromatography mass spectrometry. The results showed that the menstrual cycle of adult females in Hainan gibbon group C was 32±3.6 days and the duration of the menstrual period was 10±2.4 days. There was no significant difference in progesterone levels between individuals of different age and sex classes, no significant periodicity in the change of testosterone in the feces samples of Hainan gibbon group C, and no significant difference in the level of testosterone between individuals of the same sex and age. However, there was a significant difference in testosterone levels between adult males and adult females. By comparing the levels of testosterone in different individuals, it could be hypothesized that both juveniles in group C may be males. The results show that the circadian cycle of adult females and the sex identification of juveniles in Hainan gibbons may be inferred from differences in fecal progesterone and testosterone levels. [ABSTRACT FROM AUTHOR]

Differences/disorders of sex development can be caused by disruptions to the molecular and cellular mechanisms that control development and sex determination of the reproductive organs with 1:100 live births affected. Multiple genes are associated with 46, XY differences/disorders of sex development that can cause varying clinical phenotypes. An accurate genetic diagnosis is essential to guide clinical care for individuals with 46, XY differences/disorders of sex development and can contribute to family planning. The use of genomics in differences/disorders of sex development has grown, with several advances employed in genetic diagnosis; however, diagnostic rates have stagnated at less than 50% for these conditions. This review will discuss 46, XY differences/disorders of sex development, its molecular causes, and the genomic technologies currently utilized for diagnosis with focus on reports from the last 5 years. We also touch on the challenges in diagnosing 46, XY differences/disorders of sex development and discuss new and future technologies that promise to improved diagnostic rates for these difficult conditions. [ABSTRACT FROM AUTHOR]

Understanding the sex determination pathway and its disruptions in mosquitoes is critical for the effective control of disease vectors through genetic manipulations based on sex separation. When male hybrids of Aedes aegypti females and Ae. mascarensis males are backcrossed to Ae. aegypti females, a portion of the backcross progeny manifests as males with abnormal sexual differentiation. We discovered a significant correlation between pupal abnormalities and the feminization of subsequent adults exemplified by the relative abundance of ovarian and testicular tissues. All intersex individuals were genetic males as they expressed a male determining factor, Nix. Further, our analysis of the sex-specific splicing of doublesex and fruitless transcripts demonstrated the presence of both male and female splice variants indicating that sex determination is disrupted. A comparative transcriptomic analysis revealed similar expression levels of most female-associated genes in reproductive organs and carcasses between intersexual males and normal females. Moreover, intersexes had largely normal gene expression in testes but significant gene downregulation in male accessory glands when compared with normal males. We conclude that evolving hybrid incompatibilities between Ae. aegypti and Ae. mascarensis involve disruption of sex determination and are accompanied by changes in gene expression associated with sexual differentiation. A study of intersexual mosquito males produced by hybridization between Aedes aegypti and Ae. mascarensis identified disruption of the sex determination pathway. [ABSTRACT FROM AUTHOR]

Fem is a W‐linked gene that encodes a piRNA precursor, and its product, Fem piRNA, is a master factor of female determination in Bombyx mori. Fem has low similarity to any known sequences, and the origin of Fem remains unclear. So far, two hypotheses have been proposed for the origin of Fem: The first hypothesis is that Fem is an allele of Masc, which assumes that the W chromosome was originally a homologous chromosome of the Z chromosome. The second hypothesis is that Fem arose by the transposition of Masc to the W chromosome. To explore the origin of Fem, we determined the W chromosome sequences of B. mori and, as a comparison, a closely relative bombycid species of Trilocha varians with a Fem‐independent sex determination system. To our surprise, although the sequences of W and Z chromosomes show no homology to each other, a few pairs of homologues are shared by W and Z chromosomes, indicating the W chromosome of both species originated from Z chromosome. In addition, the W chromosome of T. varians lacks Fem, while the W chromosome of B. mori has over 100 copies of Fem. The high‐quality assembly of the W chromosome of B. mori arose the third hypothesis about the origin of Fem: Fem is a chimeric sequence of multiple transposons. More than half of one transcriptional unit of Fem shows a significant homology to RTE‐BovB. Moreover, the Fem piRNA‐producing region could correspond to the boundary of the two transposons, gypsy and satellite DNA. [ABSTRACT FROM AUTHOR]

SOX proteins are a family of transcription factors (TFs) that play critical functions in sex determination, neurogenesis, and chondrocyte differentiation, as well as cardiac, vascular, and lymphatic development. There are 20 SOX family members in humans, each sharing a 79-residue L-shaped high mobility group (HMG)-box domain that is responsible for DNA binding. SOX2 was recently shown to interact with long non-coding RNA and large-intergenic non-coding RNA to regulate embryonic stem cell and neuronal differentiation. The RNA binding region was shown to reside within the HMG-box domain; however, the structural details of this binding remain unclear. Here, we show that all SOX family members, except group H, interact with RNA. Our mutational experiments demonstrate that the disordered C-terminal region of the HMG-box domain plays an important role in RNA binding. Further, by determining a high-resolution structure of the HMG-box domain of the group H family member SOX30, we show that despite differences in RNA binding ability, SOX30 shares a very similar secondary structure with other SOX protein HMG-box domains. Together, our study provides insight into the interaction of SOX TFs with RNA. [ABSTRACT FROM AUTHOR]

Bird sex determination is fundamental in various ecological and biological studies, although many avian species cannot be sexed visually due to their monomorphic and/or monochromatic appearance. Thus, reliable laboratory methods for sexing are a prerequisite. Most avian nestlings lack sex-related signs, including the Eurasian pygmy owl (Glaucidium passerinum). We performed laboratory sex determination analysis of this species using blood samples of 242 juveniles and nine adults. It relied on the qPCR of the specific intron from the chromo-helicase DNA-binding protein 1 gene. We tested three primer sets, the P2/P8, 2550F/2718R, and CHD1F/CHD1R, commonly used for bird laboratory sexing. The outcomes were displayed on an agarose gel electrophoresis and a plot from melt curve analysis, which had not been previously conducted in Eurasian pygmy owls. We found that only primer set CHD1F/CHD1R proved reliable, as the only one determined sex with one and two band/s and peak/s on the electrophoresis and the melt curve plot for males and females, respectively. The other two primer pairs failed and depicted one band/peak in all specimens regardless of their sex. Therefore, we recommend performing Eurasian pygmy owls' laboratory sexing by qPCR with CHD1F/CHD1R primers only. [ABSTRACT FROM AUTHOR]

The evolution of separate sexes from cosexuality requires at least two mutations: a feminizing allele to cause female development and a masculinizing allele to cause male development. Classically, the double mutant is assumed to be sterile, which leads to two-factor sex determination where male and female sex chromosomes differ at two loci. However, several species appear to have one-factor sex determination where sexual development depends on variation at a single locus. We show that one-factor sex determination evolves when the double mutant develops as a male or a female. The feminizing allele fixes when the double mutant is male, and the masculinizing allele fixes when the double mutant is female. The other locus then gives XY or ZW sex determination based on dominance: for example, a dominant masculinizer becomes a Y chromosome. Although the resulting sex determination system differs, the conditions required for feminizers and masculinizers to spread are the same as in classical models, with the important difference that the two alleles do not need to be linked. Thus, we reveal alternative pathways for the evolution of sex determination and discuss how they can be distinguished using new data on the genetics of sex determination. [ABSTRACT FROM AUTHOR]

In forensic anthropology, the radius bone has been shown to determine the sex of human remains in a number of different populations. The dry mass and growth of long bones, including the radius, are associated with sex hormone levels; however, the use of bone weight to determine sex has not been sufficiently investigated. The aim of this study was to apply bone morphometric parameters, including maximum length of radius (MLR), circumference at the midshaft of radius (CMR), and weight of radius (WR), to 400 sample radii from a Northeastern Thai population. Univariate and multivariate discriminant functions of all parameters were systemically applied. Equations for calculating sex classification were also determined. Descriptive data analysis showed significant sexual dimorphism in all variables (p < 0.05). The canonical correlation was highest in CMR (0.772) and the ratio of weight to length (0.747). Multivariate discriminant function analysis showed that the measured indices of the right radius were slightly greater than those of the left radius. The parameters demonstrating the highest values of the standardized canonical discriminant function coefficients were CMR (Rt. = 0.496, Lt. 0.431) and WR (Rt. = 0.681, Lt. = 0.715). Moreover, the results of the multivariable (stepwise method) indicated that the best accuracy rates for using combinations of CMR and WR were 94 % (right side) and 92 % (left side). In conclusion, the weight of the radius (rather than the length) is an effective parameter in determining sex. [ABSTRACT FROM AUTHOR]

In this study, we aim to share the volumes of the carpal bone and the ratio of these volumes to the total volume of wrist bones from Computed Tomography (CT) images obtained from individuals of different ages and sex using 3D Slicer. Right wrist CT images of 0.625 mm slice thickness of 42 healthy individuals (21 female, 21 male) of both sexes were included in our study. Volume calculations were made by loading the images into 3D Slicer, an open-source software package. In this study, mean capitate volume was the largest in both sexes (male 3479.9±679.2; female 2207.1±272.1 mm3), while pisiform had the smallest mean volume (male 810.0±141.2; female 566.6±97.7 mm3). This order was ordered from largest to smallest as hamate, scaphoid, trapezium, lunate, triquetrum, trapezoid, and pisiform. According to this study, carpal bone volumes were larger in males than in females (p<0.001). The ratio of each carpal bone volume to the total carpal bone volume was calculated according to sex and it was found that there was no difference (p>0.05). In this study, it was seen that carpal bone volume differed according to sex. However, it was observed that the bone volumes of both sexes took up the same amount in the total bone volume. This information will be very useful in sex determination, 3D anatomical material creation, implant applications and reconstructive surgery. [ABSTRACT FROM AUTHOR]

Since machine learning algorithms give more reliable results, they have been used in the field of health in recent years. The orbital variables give very successful results in classifying sex correctly. This research has focused on sex determination using certain variables obtained from the orbital images of the computerized tomography (CT) by using machine learning algorithms (ML). In this study 12 variables determined on 600 orbital images of 300 individuals (150 men and 150 women) were tested with different ML. Decision tree (DT), K-Nearest Neighbour (KNN), Logistic Regression (LR), Random Forest (RF), Linear Discriminant Analysis (LDA), and Naive Bayes (NB) algorithms of ML were used for unsupervised learning. Statistical analyses of the variables were conducted with Minitab® 21.2 (64-bit) program. ACC rate of NB, DT, KNN, and LR algorithms was found as % 83 while the ACC rate of LDA and RFC algorithms was determined as % 85. According to Shap analysis, the variable with the highest degree of effect was found as BOW. The study has determined the sex with high accuracy at the ratios of 0.83 and 0.85 through using the variables of the orbital CT images, and the related morphometric data of the population under question was acquired, emphasizing the racial variation. [ABSTRACT FROM AUTHOR]

The aim of this study was to derive the equations for sex determination and to test the accuracy of discrimination between sexes using measurements of the patella in the Thai population. The sample comprised 254 Thai skeletons (134 males and 120 females) aged between 22 and 97 years, with an average age of 63.3years, obtained from the Osteology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai. Six variables were measured in 254 pairs of normal patellae. The mean values of patellar measurements in males were significantly greater than those in females for all variables (P<0.05). Statistical analysis further showed that all variables were useful in sex determination. Stepwise discriminant function analysis yielded an accuracy of 83.2 % (83.8 % male, 82.5 % female) and 85.5 % (85.3 % male, 85.8 % female) for the left and right patellae, respectively. These results suggested that measurement of the right patella is preferable for skeletal sexing. If this is not available, the forensic specialist can use the left patella instead, with an average accuracy of more than 80.0 % in giving a correct classification. The findings of this study demonstrate that the patella is an important bone in sex determination. They suggest that either the left or right patella can be used for sex determination, especially in the Northern Thai population. [ABSTRACT FROM AUTHOR]

There are very few sex estimation methods specifically designed for or tested on Belgian skulls. The currently used methods for European populations have been developed using North American collections where individuals are categorized as White and/or having European ancestry. These frequently show discordance between the pelvic sex and cranial sex estimations highlighting the need for population specific methods. To fill this gap in our knowledge, several sex estimation methods, using 15 qualitative skull features, were tested on two Flemish (northern Belgium) skeletal collections; one archaeological (15th–17th century) and one forensic (20th century). The features were tested by themselves as well as in different combinations using logistic regression. The glabella is considered the best lone feature with a minimal accuracy of 78.4% and a sex bias of −5.2%. Furthermore, four sex estimation equations were developed for the skull, the cranium, the mandible, and the frontal bone separately. The skull has an accuracy of 89.3% and a bias of 0.8%. For the cranium, this is 87.5% and −0.3%, respectively, for the mandible 85.1% and −0.1%, and for the frontal bone it is 80.4% and −4.6%. The various tests confirm that many skull features can be used for sex estimation and can generate high sex estimation accuracy. [ABSTRACT FROM AUTHOR]