Project description:We recently identified a missense mutation in Nucleoporin107 (Nup107; D447N) underlying XX-ovarian-dysgenesis (XX-OD), a disorder characterized by underdeveloped and dysfunctional ovaries. Specific knockdown of Nup107 in the somatic gonadal cells and moreover, modelling of the human mutation in Drosophila result in ovarian-dysgenesis-like phenotypes in female flies. The aberrant phenotypes in larval and adult ovaries compromised for Nup107 are associated with hyperactivation of BMP signalling. Transcriptomic analysis identified the somatic sex-determination gene Doublesex (dsx) and the extracellular metalloprotease AdamTS-A as targets of Nup107. Either loss or gain of Dsx in the gonadal soma is sufficient to respectively mimic or rescue the phenotypes induced by Nup107 loss. Furthermore, adamTS-A is transcriptionally regulated by Dsx, and its knockdown in the somatic gonad hyperactivates BMP signaling and to a large extent recapitulates loss of Nup107 phenotypes. Thus, Dsx acts downstream of Nup107 to impact female germline stem cells via sex-specific modulation of the BMP pathway.
Project description:Purpose: Sexual dimorphisms fuel significant intraspecific variation and evolutionary diversification. Yet the developmental-genetic mechanisms underlying sex-specific development remain poorly understood. We focused on the conserved sex-determination gene doublesex (dsx) and the mechanisms by which it mediates sex-specific development in a species of horned beetle by combining systemic dsx knockdown, high-throughput sequencing of diverse tissues, and a genome-wide analysis of Dsx binding sites. We find that Dsx regulates sex-biased expression predominantly in males, that Dsx's target repertoires are highly sex- and tissue-specific, and that Dsx can exercise its regulatory role via two distinct mechanisms: as a sex-specific modulator by regulating strictly sex-specific targets, or as a switch by regulating the same genes in males and females in opposite directions. More generally, our results suggest Dsx can rapidly acquire new target gene repertoires to accommodate evolutionarily novel traits, evidenced by the large and unique repertoire identified in head horns, a recent morphological innovation.
Project description:The survival and reproductive success of animals depends on the ability to harmonize their external behaviors with their internal states. For example, females conduct numerous social programs that are distinctive to virgins compared to post-mated and/or pregnant individuals. In Drosophila, the fact that the post-mating switch is initiated by seminal factors implies the default state as virgin. Recently, we uncovered molecular and genetic control of the female virgin state. In particular, repression of the transcription factor Homothorax (Hth) by mir-iab-4/8 within the abdominal ventral nerve cord (VNC) is critical for unmated females to execute virgin behaviors. To elucidate new components of this regulatory circuit, we exploited mir-iab-4/8 deletion and hth-miRNA binding site mutants (hth[BSmut]) to elucidate doublesex (dsx) as a critical downstream factor. While Dsx has mostly been studied during sex-specific differentiation, its activities in neurons are little known. We find that accumulation of Dsx in the CNS is mutually exclusive with Hth, and downregulated in miRNA/hth[BSmut] mutants. Moreover, experimental suppression of Dsx in highly restricted sets of abdominal neurons abrogates female virgin conducts, in favor of mated behavioral programs. Thus, a double negative pathway in the VNC mediates the virgin behavioral state.
Project description:MicroRNAs (miRNAs) are a highly conserved class of small RNAs which function in a sequence-specific manner to post-transcriptionally regulate expression of target genes. Tissue-specific miRNA expression studies have discovered numerous functions for miRNAs in various aspects of embryonic development, but a role for miRNAs in gonadal development and sex differentiation has not yet been reported. Using the chicken embryo as a vertebrate model, differential miRNA expression between male and female embryonic gonads, was analysed at three developmental stages (embryonic days (E) 5.5, E6.5 and E9.5), using custom-designed 4x2K CombiMatrix miRNA microarray. The aims of this study were to: 1-identify miRNAs differentialy expressed by sex; 2-identify sex-specific miRNAs; 3-analyse global changes in miRNA up-regulation in male versus female gonads before, during and after the histological onset of sexual differentiation. This study provides a basis for establishing whetehr miRNAs are involved in either initiating or regulating vertebrate gonadal sex differentiation. Keywords: miRNA, sex comparison, developmental stage comparison. miRNA samples from male and female embryonic chicken gonads from three developmental stages: embryonic day (E) 5.5 (Hamilton & Hamburger (HH) stage 27-28), E6.5 (HH stage 29-30) & E9.5 (HH stage 35-36). Samples are listed with biological replicates used for analysis in brackets following: 1 - Male E5.5 (5); 2 - Female E5.5 (4); 3 - Male E6.5 (5); 4 - Female E6.5 (3); 5 - Male E9.5 (4); 6 - Female E9.5 (4).
Project description:Sexual dimorphism of the skeleton is well documented. At maturity, the male skeleton is typically larger and has a higher bone density than the female skeleton. However, the underlying mechanisms for these differences are not completely understood. In this study, we examined sexual dimorphism in the formation of osteoclasts between cells from female and male mice. We found that the number of osteoclasts in bones was greater in females. Similarly, in vitro osteoclast differentiation was accelerated in female osteoclast precursor (OCP) cells. To further characterize sex differences between female and male osteoclasts, we performed gene expression profiling of cultured, highly purified, murine bone marrow OCPs that had been treated for 3 days with M-CSF and RANKL. We found that 125 genes were differentially regulated in a sex-dependent manner. In addition to genes that are contained on sex chromosomes, transcriptional sexual dimorphism was found to be mediated by genes involved in innate immune and inflammatory response pathways. Furthermore, the NFκB-NFATc1 axis was activated earlier in female early osteoclasts, which partially explains the differences in transcriptomic sexual-dimorphism in these cells. Collectively, these findings identify a sex-dependent intrinsic difference in early osteoclasts, which results from an altered response to osteoclastogenic stimulation. In humans these differences could contribute to the lower peak bone mass and increased risk of osteoporosis that females demonstrate relative to males.
Project description:MicroRNAs (miRNAs) are a highly conserved class of small RNAs which function in a sequence-specific manner to post-transcriptionally regulate expression of target genes. Tissue-specific miRNA expression studies have discovered numerous functions for miRNAs in various aspects of embryonic development, but a role for miRNAs in gonadal development and sex differentiation has not yet been reported. Using the chicken embryo as a vertebrate model, differential miRNA expression between male and female embryonic gonads, was analysed at three developmental stages (embryonic days (E) 5.5, E6.5 and E9.5), using custom-designed 4x2K CombiMatrix miRNA microarray. The aims of this study were to: 1-identify miRNAs differentialy expressed by sex; 2-identify sex-specific miRNAs; 3-analyse global changes in miRNA up-regulation in male versus female gonads before, during and after the histological onset of sexual differentiation. This study provides a basis for establishing whetehr miRNAs are involved in either initiating or regulating vertebrate gonadal sex differentiation. Keywords: miRNA, sex comparison, developmental stage comparison.
Project description:In UV sexual systems, sex is determined during the haploid phase of the life cycle and males have a V chromosome whereas females have a U chromosome. Previous work in the model Ectocarpus revealed that the V chromosome has a dominant role in male sex determination and the female developmental program being a ‘default’ program, triggered in the absence of the male master sex determination gene(s). Here, we describe the identification of a genetically male giant kelp strain presenting phenotypic features typical of a female, despite lacking the U-specific region. The conversion to the female developmental program is however incomplete, because gametes of this feminised male are unable to produce the sperm-attracting pheromone lamoxiren. We identify the transcriptomic pathways underlying the male and female specific developmental programs and show that the phenotypic feminisation of the variant strain is associated with both feminisation and de-masculinisation of gene expression patterns. Importantly, the feminisation phenotype was associated with the dramatic downregulation of two V-specific genes including a candidate sex-determining gene on the V-specific region. Our results reveal the transcriptional changes associated with sexual differentiation in a UV system with extensive sexual dimorphism, disentangling the role of sex-linked genes and autosomal gene expression in the initiation of the male and female developmental programs. Overall, the data presented here imply that the U-specific region in the giant kelp is not required to initiate the female developmental program, but is critical to produce fully functional eggs, arguing against the idea that female is the ‘default’ sex in this species.
Project description:By combining an experimental evolution approach with genomic techniques, we investigated the effects of seminal fluid on female gene expression. In our study, we experimentally manipulated the mating system in replicate populations of D. melanogaster, by removing post-copulatory sexual selection, with the aim of testing differences in short term post-mating reaction of females evolved under different mating strategies. We show that monogamous females suffer decreased fecundity, regardless of the type of male they were mated with, and that their post-mating gene expression profiles differ significantly from promiscuous females, involving 1141 transcripts (9% of the genes tested). These transcripts are active in several tissues, mainly ovaries, neural tissues, midgut and spermathecae, and are involved in metabolic processes, reproduction and signaling pathways. Our results provide a list of candidate genes responsible for the decrease in female fecundity in the absence of post-copulatory sexual selection, and demonstrate how the female post-mating response can evolve under different mating systems over relatively short time frames.
Project description:By combining an experimental evolution approach with genomic techniques, we investigated the effects of seminal fluid on female gene expression. In our study, we experimentally manipulated the mating system in replicate populations of D. melanogaster, by removing post-copulatory sexual selection, with the aim of testing differences in short term post-mating reaction of females evolved under different mating strategies. We show that monogamous females suffer decreased fecundity, regardless of the type of male they were mated with, and that their post-mating gene expression profiles differ significantly from promiscuous females, involving 1141 transcripts (9% of the genes tested). These transcripts are active in several tissues, mainly ovaries, neural tissues, midgut and spermathecae, and are involved in metabolic processes, reproduction and signaling pathways. Our results provide a list of candidate genes responsible for the decrease in female fecundity in the absence of post-copulatory sexual selection, and demonstrate how the female post-mating response can evolve under different mating systems over relatively short time frames.