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At least 19 recordsLinked to original sources
PubMed1989

Genes that implement the hermaphrodite mode of dosage compensation in Caenorhabditis elegans.

We report a genetic characterization of several essential components of the dosage compensation process in Caenorhabditis elegans. Mutations in the genes dpy-26, dpy-27, dpy-28, and the newly identified gene dpy-29 disrupt dosage compensation, resulting in elevated X-linked gene expression in XX animals and an incompletely penetrant maternal-effect XX-specific lethality. These dpy mutations appear to cause XX animals to express each set of X-linked genes at a level appropriate for XO animals. XO dpy animals are essentially wild type. Both the viability and the level of X-linked gene expression in XX animals carrying mutations in two or more dpy genes are the same as in animals carrying only a single mutation, consistent with the view that these genes act together in a single process (dosage compensation). To define a potential time of action for the gene dpd-28 we performed reciprocal temperature-shift experiments with a heat sensitive allele. The temperature-sensitive period for lethality begins 5 hr after fertilization at the 300-cell stage and extends to about 9 hr, a point well beyond the end of cell proliferation. This temperature-sensitive period suggests that dosage compensation is functioning in XX animals by mid-embryogenesis, when many zygotically transcribed genes are active. While mutations in the dpy genes have no effect on the sexual phenotype of otherwise wild-type XX or XO animals, they do have a slight feminizing effect on animals whose sex-determination process is already genetically perturbed. The opposite directions of the feminizing effects on sex determination and the masculinizing effects on dosage compensation caused by the dpy mutations are inconsistent with the wild-type dpy genes acting to coordinately control both processes. Instead, the feminizing effects are most likely an indirect consequence of disruptions in dosage compensation caused by the dpy mutations. Based on the cumulative evidence, the likely mechanism of dosage compensation in C. elegans involves reducing X-linked gene expression in XX animals to equal that in XO animals via the action of the dpy genes.

Animals↗
PubMed1992

Plasticity of gonadal development and protandry in fishes.

Sexual differentiation in eutherian mammals follows a simple governing paradigm: development proceeds in a female direction unless a masculinizing mechanism intervenes. Sexual development in fishes is much more plastic than in mammals. It permits the intervention of environmental factors and follows several different types of sequences that produce successive hermaphrodites and alternative pathways for the development of the same final sex. In spite of this plasticity, the primacy of female development is suggested by the initial ovarian phase in the development of gonads of both sexes in some gonochoristic fishes and by protogynous sex change. One barrier to the application of this principle to fishes generally is the existence of protandric hermaphrodites. Recent evidence suggests a reinterpretation of gonadal differentiation in a protandric anemonefish and a protandric sparid. In both cases, testicular development is both preceded and followed by ovarian development. These patterns are interpreted to mean that female development is primary and that male development is a temporary phase initiated by a masculinizing mechanism and terminated by its cessation.

Animals↗
PubMed1991

Regulation of sexual succession in the protogynous black sea bass, Centropristis striatus (Osteichthyes: Serranidae)

Serum levels of 17 beta-hydroxy-4-androstene-3,11-dione (11-KT) and testosterone in the protogynous black sea bass, Centropristis striatus fluctuate annually, correlated with the breeding season. Although serum 11-KT levels in both males and females exhibit seasonality, serum estradiol-17 beta concentrations cycle annually only in the females. Throughout the year, serum estradiol levels in males (127 +/- 56 pg/ml, mean +/- SD) were significantly (P less than 0.05) less than levels in breeding (3,930 +/- 1,390 pg/ml), or nonbreeding females (261 +/- 62 pg/ml). In all female sea bass not undergoing sexual succession, histological examination of the ovary revealed only spermatogonia or ongoing spermatogenesis restricted to the posterior male lamellae; a duct system was nonexistent. In female fish undergoing sexual succession, ovarian tissue was always nonvitellogenic and regressing. Breeding females were not observed to undergo gender change. During sexual succession in the postspawning period, male tissue spread into neighboring female lamellae containing oocytes, gradually replacing them and other female tissue. A male duct system developed on the surface. At any time of year, black sea bass undergoing sexual succession had serum estradiol levels (79 +/- 19 pg/ml) which were significantly less (P less than 0.05) than concurrent female serum estradiol levels. A chi-square test demonstrated that serum estradiol levels in these intersex animals were not significantly different from those of males. The possibility is discussed that sexual succession results from inhibition of ovarian tissue response to steroidogenic gonadotropin.

Aging↗
PubMed2025

GT1 regulates maize sex determination by affecting the jasmonate pathway.

Maize (Zea mays L.) is a monoecious plant with male and female flowers physically separated on different inflorescences-the tassel and the ear. Maize sex determination is controlled by a series of complicated developmental signals. Here, we characterized an EMS-induced maize feminized tassel mutant,tasselsilk1 (tsk1), and identified GRASSY TILLERS1 (GT1) as the causative gene. Phenotypic analysis of tsk1 mutants revealed that pistils fail to abort in both the tassel and ear, resulting in long sterile silks in the tassel and the development of an extra small kernel from the lower floret in the ear. RNA-seq and CUT&Tag analysis indicated that GT1 functioned as a repressor for flower organ development by regulating the JA biosynthesis and signaling pathways, specifically by directly promoting the expression of TASSELSEED1 (TS1), ZmMYC2A, ZmMYC2B. Together, we identified a new allele of GT1 and proposed that GT1 functions through JA biosynthesis and signaling pathways to regulate sex determination in maize.

Zea mays↗
PubMed1978

[The role of the adrenal gland in sex determination of the duck embryo].

In duck embryos, a study was made of the role the suprarenal glands might play in the process of sex determination. The experiments included the transplantation of suprarenal gland taken from embryos aged from 9 to 25 days, into the coelomic cavity of embryos ranging from 71 to 139 hours of age. Out of a total of 388 transplantations, 222 succeeded in the sense that the hosts reached the age, at which the gonads have sexually differentiated. The results show that the implantation of a suprarenal gland does not influence the sex-ratio. Moreover, no disturbances in the development of the gonads were observed. Hence, the conclusion may be drawn that it is highly improbable that the suprarenal gland plays an essential role in the production of substances guiding the differentiation of the gonadal primordia into ovaries or testes.

Adrenal Glands↗
PubMed2025

Influence of Gonadal and Chromosomal Sex on the Brain Transcriptome in a Mouse Species with Natural Sex Reversal.

Sex chromosomes are expected to play a role in shaping the transcriptional architecture of sexual dimorphism, through the direct expression of sex-linked genes, by regulating autosomal genes, or in interactions with hormones. Yet, their degree of involvement remains elusive partly because chromosomal sex (e.g. XX/XY) and gonadal sex (ovaries or testes) are usually inextricably intertwined. They are, however, dissociated in the African pygmy mouse, Mus minutoides, in which a feminizing X (X*) has evolved, resulting in three female genotypes (XX, XX*, and X*Y) and one male genotype (XY). Furthermore, all sex chromosomes are fused to autosomes (neo-sex chromosomes: neo-X, neo-X* and neo-Y). Despite complete sex reversal, X*Y females show distinctive phenotypes with greater fertility, divergent maternal care strategies, and the masculinization of some traits (e.g. enhanced aggressiveness). By comparing the brain transcriptome of the four sexual genotypes, we show that differential gene expression is mainly linked to gonadal sex but also, and significantly, to chromosomal sex. Genes influenced by chromosomal sex are overrepresented on sex-linked genomic regions, and some are strong candidates to explain X*Y-specific behavioral and reproductive traits. Our results also suggest the preferential inactivation of the X* chromosome in XX* females, only in the brain, which could explain their trait similarities with XX females. Overall, we show that sex and neo-sex chromosomes have profoundly impacted the brain transcriptome in ways that reflect their new transmission modes, evolutionary trajectories, and resulting genomic conflicts.

Animals↗
PubMed2026

Same Sex Chromosomes With Independent Origins in Haplochromine Cichlids.

Elucidating theories of sex chromosome evolution requires approaches that allow fine scale delimitations of sex-determining regions within a phylogenetic context. This can address whether shared sex chromosomes across related species are due to shared ancestry, or whether genetic sex-determining regions have repeatedly evolved. Haplochromine cichlids, as one of the most successful fish lineages on Earth, have been a focal study system of sex chromosome research, both because of their rapid rate of sex chromosome turnover and the repeated emergence of certain sex chromosomes across the lineage. Here, we newly describe sex chromosomes in members of the earliest branch of the modern haplochromines, the Tropheini, based on whole-genome sequencing data, using a combination of SNP- and kmers-based methods. We show that despite the repeated co-options of ancestral chromosomes LG5 and LG7 in these species, the origins of these sex chromosomes are independent. Investigation of gene functions, allele differences, and sex-biased gene expression within the discovered sex-linked regions provides no evidence that sexual antagonism has driven the repeated evolution of a region on LG5 that overlaps between four of these species. By comparing the sex-determining regions on LG5 and LG7 across haplochromines, we show that a common origin is unlikely, and that while sex chromosomes themselves may be shared between several Haplochromini, the sex-determining genes or mechanism likely differ. This study paves the way to explore newly emerging theories of sex chromosome evolution, such as the role of chromosomal fusion or recombination patterns across the genome.

Animals↗
PubMed2026

A duplicated female pathway gene figla-like evolves as the male sex-determining gene in tilapia.

As the largest group of vertebrates, fish exhibit frequent turnover of sex-determining (SD) genes. Here, we assemble a chromosome-level YY red tilapia genome and identify figla-like (figlal) as the SD gene on tilapia linkage group (LG) 1. Integrative phylogenetic and genomic evidence suggests that figlal originated from a tilapia-specific duplication and transposition of the ancestral bHLH family gene figla from LG12 to LG1. Fluorescence in situ hybridization reveals expression divergence between figla and figlal, with figla expressed in female oocytes and figlal expressed in male gonadal somatic cells during early gonadal differentiation. The shift in expression after duplication might be driven by the insertion of cis-regulatory elements mediated by transposable elements. Knockout of figlal in XY fish results in male-to-female sex reversal as indicated by ovarian morphology, down-regulation of the male pathway gene dmrt1, and up-regulation of the female pathway gene cyp19a1a in the gonads. In contrast, overexpression of figlal in XX fish induces female-to-male sex reversal. These findings implicate figlal as an SD gene on tilapia LG1 and reveal the history of a unique evolutionary innovation in which a female oocyte gene evolved into a male SD gene via duplication, transposition, and cis-regulatory rewiring.

Animals↗
PubMed2025

Extensive Recombination Suppression and Genetic Degeneration of a Young ZW Sex Chromosome System in Halfbeak Fish.

Sex chromosome systems have evolved independently across the tree of life, at different times in the past, and the evolutionary consequences of lacking recombination in sex-linked regions have been characterized in many old-established systems. However, empirical studies of young sex chromosomes are still scarce, especially in vertebrates. Integrating whole-genome sequencing data of two species of halfbeak fish, Hyporhamphus sajori and Hyporhamphus intermedius, we identified the sex-determining system in H. sajori as female heterogamety, involving a large fully sex-linked ZW region (∼26 Mb) on chromosome 5. The closest relative, H. intermedius, has a small sex-linked region on a different chromosome and shows male heterogamety, suggesting at least one turnover in this fish genus. The H. sajori sex-linked region includes two evolutionary strata, but the estimated Z-W divergence times are small, less than 3 million years for the older stratum, which is less than between the two species. Nevertheless, this evolutionarily young W-linked region is enriched with repetitive sequences, differs from the ancestral state by five inversions, and about one-third of its protein-coding genes have already become nonfunctional. Transcriptomic analysis suggests that some form of dosage compensation may already be evolving for some sex-linked genes.

Animals↗
PubMed2026

The gonadal matrisome and its correlation with sex change in the ricefield eel Monopterus albus.

The matrisome is a comprehensive list of genes in the genome of an organism, which encodes proteins constituting or interacting with the extracellular matrix (ECM). The gonadal ECM is important for folliculogenesis and spermatogenesis. This study characterized the composition of the matrisome and the expression of matrisome genes in the gonad of ricefield eel, a protogynous sex-changing teleost, during sex change. A total of 838 matrisome genes were identified in the genome of ricefield eel through an in-silico orthology-based approach, of which 482, 443, 429, and 570 matrisome genes were shown to be expressed in the gonads of female (F), early intersexual (EI), mid-intersexual (MI), and late intersexual (LI) fish, respectively. Differentially expressed matrisome genes (DEMGs) were observed across all the sexual stages as well as in each category of ECM components. Analysis of DEMGs in the comparison between EI and F revealed dramatic upregulation of adam8a, mmp9, and s100a11 while downregulation of col4a5, col15a1b, clec3ba, f13a1, and ccl44, which were further confirmed by qPCR analysis. Together, these findings revealed significant changes in the expression of many matrisome genes, particularly three regulator genes, adam8a, mmp9 and f13a1, as female ricefield eels initiate sex change, suggesting that gonadal tissues undergo dramatic remodeling involving the regression of ovarian tissues and the development of testicular tissues to facilitate this process. These data provide valuable resources for further unraveling the roles of matrisome genes in gonadal development of ricefield eel and other vertebrates.

Animals↗
PubMed2025

Transposable Element-Mediated Cis-Regulation Drives the Evolution of dmrt1 as a Candidate Master Sex-Determining Gene in Black Carp.

Sex determination in vertebrates exhibits remarkable evolutionary plasticity, with diverse mechanisms and master sex-determining (MSD) genes arising independently across lineages. Among these, dmrt1, a dosage-sensitive gene, has repeatedly been recruited as an MSD gene through gene duplication or allelic diversification. However, the biochemical basis of such evolutionary transitions, particularly those driven by allelic diversification, remains largely unexplored. Here, we generated haplotype-resolved genome assemblies for both XX and XY black carp (Mylopharyngodon piceus) and identified a ∼40-kb region on chromosome 4, containing only dmrt1, as the candidate sex-determining locus. We discovered two Y-specific insertions in the dmrt1 promoter: a 13.4-kb highly repetitive element and an 11-bp motif. Functional assays revealed that these insertions act as enhancer and a promoter element, respectively, driving early, allele-specific upregulation of dmrt1 prior to gonadal differentiation. Notably, the 13.4-kb insertion contains transposable elements (TEs) functioning as cis-regulatory modules with transcription factor binding sites that mediate Y-specific activation. Our findings reveal a TE-mediated regulatory innovation that promoted dmrt1's evolution as a male-determining gene via allelic diversification, providing new insights into how mobile genetic elements drive the origin and diversification of sex-determining systems in vertebrates.

Animals↗
PubMed1990

The Drosophila melanogaster fl(2)d gene is needed for the female-specific splicing of Sex-lethal RNA.

In Drosophila melanogaster, sex determination and dosage compensation are under the control of the Sex-lethal (Sxl) gene. We have identified a gene, female-lethal-2-d (fl(2)d), located in the second chromosome, that interacts with Sxl. fl(2)d homozygous clones, induced during the larval stage of fl(2)d/+ females, develop male structures instead of female ones. fl(2)d homozygous females hypertranscribe their two X chromosomes, as measured by comparing the level of the X-linked sgs-4 transcript, which is dosage compensated, with that of the autosomal sgs-3 transcript. Thus, with respect to the processes of sex determination and dosage compensation, loss-of-function mutations at the fl(2)d and at the Sxl genes are equivalent. Moreover, fl(2)d homozygous female larvae express the Sxl transcripts characteristic of males. These results indicate that the fl(2)d gene is needed for the sex-specific splicing pattern of the Sxl RNA that occurs in females, thus suggesting the involvement of the fl(2)d gene in the positive autoregulatory pathway of Sxl.

Animals↗