Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.64898/2026.06.26.731870

Whole-genome duplication underlies conserved sexually biased expression of meiotic cohesin genes unique to the teleost fish lineage

Niwa, T.·Kikuchi, M.·Tanaka, M.
View original source ↗Export metadata ↓

Abstract

Meiosis is a fundamental process in producing both sperm and eggs, yet recombination landscapes often exhibit sexual differences, known as heterochiasmy. Since meiotic proteins are generally expressed in both sexes, the molecular mechanism driving heterochiasmy remains elusive. The -kleisin subunit gene of meiotic cohesin, Rec8, is expressed bisexually in mammals, while its putative teleost ortholog, rec8a, is expressed in a female-biased manner, presumably due to the presence of its paralog originating from the teleost-specific whole-genome duplication (TGD). Here, we elucidated the evolutionary history and expression dynamics of -kleisin genes across teleost lineages. Through comprehensive phylogenetic and synteny analyses, we revealed that major teleost lineages retain two copies of rec8 and rad21, with rec8 loci experiencing drastic chromosomal rearrangements immediately after the TGD. Using in situ hybridization and single-cell transcriptome data in medaka and zebrafish, we demonstrated a conserved sexually biased expression pattern: rec8a is predominantly female-biased, whereas rec8b exhibits male-biased expression during gametogenesis. Furthermore, comparative epigenetic analyses revealed that the conserved sexually biased expression is driven by lineage-specific cis-regulatory elements, rather than conserved ones. Motif analyses imply that regulatory rewiring by transcription factors, including foxl2l in particular, might have played a crucial role in the establishment and maintenance of this paralog divergence. Our findings highlight how whole-genome duplication and subsequent genomic and epigenetic rewiring subdivided the bisexual function of rec8, offering insights into sexually distinct meiotic regulation. HighlightsO_LITeleosts possess a unique -kleisin repertoire originating from the TGD. C_LIO_LITeleost rec8 paralogs exhibit conserved sex-biased expression during meiosis. C_LIO_LIDrastic genomic rearrangements after the duplication rewired the teleost rec8 loci. C_LIO_LIThe conserved expression pattern is governed by lineage-specific CREs. C_LIO_LIThose CREs harbor similar types of TFBSs such as Fox-family TFs. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=94 SRC="FIGDIR/small/731870v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@c8c84dorg.highwire.dtl.DTLVardef@1d65668org.highwire.dtl.DTLVardef@c2d732org.highwire.dtl.DTLVardef@1be54a2_HPS_FORMAT_FIGEXP M_FIG C_FIG

Explore related subjects

Developmental BiologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Niwa, T., Kikuchi, M., Tanaka, M.. 2026-06-27. Whole-genome duplication underlies conserved sexually biased expression of meiotic cohesin genes unique to the teleost fish lineage. https://doi.org/10.64898/2026.06.26.731870

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Neural tracking of stressed syllables in Dutch nursery rhymes relates to vocabulary outcomes in a large, longitudinal sample

Speech consists of regularities at different timescales. Already during infancy, neural electrophysiological activity aligns to these rhythms. The degree to which infants exhibit neural tracking of speech can be linked to their language development. In this study, we examined how the neural tracking of sung speech develops across age, from infancy to early childhood, and across different frequency bands (i.e., at the stress, syllabic, and phonemic rates), and whether neural tracking at each frequency and age predicts childrens language outcomes. We included 2565 children of the longitudinal YOUth cohort. Children listened to Dutch sung nursery rhymes while EEG was recorded at three measurement waves. After preprocessing the data, we included 955 children at 5 months, 1048 children at 10 months, and 795 children at 2-4 years. The final sample consisted of 750 children who also completed a receptive vocabulary test at 2-4 years. Children from 5 months onwards showed significant neural tracking of stressed syllables, syllables, and phonemes, measured with speech-brain coherence (SBC). Unexpectedly, there were no developmental changes in SBC across different frequency bands from infancy to early childhood. As expected, children with larger receptive vocabularies showed increased SBC in the stressed syllable rate. These findings suggest that stronger tracking of stressed syllables is related to individual differences in language ability.

Developmental Biology↗
bioRxiv2026

FGF Signaling Potentiates Müller Glia for Mammalian Retinal Regeneration

Muller glia possess latent regenerative potential that could be harnessed to restore retinal neurons lost to injury or disease. Although fibroblast growth factor (FGF) signaling is upregulated following retinal damage, its role in mammalian retinal regeneration remains unclear. Here, we investigated the function of FGF signaling in Muller glial reprogramming using genetic, pharmacological, and single-cell transcriptomic approaches. Activation of FGF signaling alone was insufficient to induce Muller glial proliferation in the mouse retina. However, conditional deletion of FGFR1/2 in Muller glia abolished regenerative responses induced by multiple independent pathways, demonstrating that FGF signaling is essential for regenerative competence. Mechanistically, loss of FGF signaling impaired sustained ERK/MAPK activation following injury, while MEK/ERK inhibition phenocopied the regenerative defect. Conversely, constitutive MEK activation induced limited Muller glial proliferation in the absence of injury. Although STAT3/5 inhibition synergized with Activin-A to promote robust proliferation and neurogenic gene expression, it failed to rescue regeneration in FGF-deficient Muller glia. Single-cell RNA sequencing revealed that FGF signaling suppresses multiple anti-regenerative programs, including Hes1, S1pr1, p27, NF-{kappa}B, and p300/CBP activity. Together, these findings identify FGF signaling as a critical permissive regulator of mammalian retinal regeneration that potentiates Muller glia through sustained ERK activation and suppression of transcriptional barriers to regeneration.

Developmental Biology↗
bioRxiv2026

Doublesex- mediated regulation of insulin signaling drives sex-specific body growth

Most animals develop sex-biased body sizes driven by sexually divergent plasticity in nutrient-dependent growth. Prior work in Drosophila, implicated the sex-determination gene transformer (tra) in regulation of sex differences in body size. However, tra does not widely mediate sex determination across insects. Thus, the unifying molecular pathway governing female-biased sexual size dimorphism (SSD) remains poorly established in non-drosophilid insects. The rice stem borer Chilo suppressalis, a devastating lepidopteran crop pest, exhibits a robust SSD, offering an ideal system to dissect underlying mechanisms. We report that female-specific splice forms of the sex-determining gene doublesex (Csdsx) are master regulators of female-biased growth. Disruption of the female-specific Csdsx exon 3 via CRISPR knockout or RNA interference drastically reduces female body size and completely erases the SSD. Csilp2, encoding a key insulin-like peptide (ILP2), is selectively upregulated in late-instar female larvae, and female CsDsx proteins directly bind and activate the Csilp2 promoter to boost transcription. Loss-of-function of Csilp2 eliminates the SSD by suppressing female somatic overgrowth. Our results identify a novel regulatory cascade: female-specific Dsx directly stimulates insulin signaling via Csilp2, bridging core sex-determination circuitry and nutrient-dependent body growth control. SignificanceSexual size dimorphism (SSD), widespread across insects with larger females, strongly shapes reproductive fitness. Yet reports on the molecular connection between sex determination and dimorphic growth are scarce. Using a major agricultural pest, the rice stem borer with a prominent female-biased SSD, we show that female-specific Doublesex (dsx) splice variants directly activate the promoter of Insulin-like peptide 2 in late larvae to trigger increased growth. Knocking out either gene in females abolishes the SSD. Our findings thus establish dsx as a novel link connecting sex-determination, insulin signaling and nutrient-dependent body growth.

Developmental Biology↗