The chromosome-level genome of Mesobuthus martensii provides insights into its evolution and the diversity of venom peptides

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  The chromosome-level genome of Mesobuthus martensii provides insights into its evolution and the diversity of venom peptides Abstract Mesobuthus martensii , the source species of the traditional Chinese medicine “Quanxie”, has long been utilized for its therapeutic properties. Venom peptides are recognized as the major active molecular basis of these pharmacological activities. Despite this, their development as therapeutic agents remains poorly explored. In this study, we performed an integrated multi-omics investigation to systematically explore the venom peptides of Mesobuthus martensii . We generated a chromosome-level genome assembly of Mesobuthus martensii using third-generation sequencing technologies, yielding a genome size of 1.08 Gb with a contig N50 of 46.46 Mb. Integrated genomic and transcriptomic analyses led to the identification of 51 putative novel venom peptide candidates. From the broader venom peptide set, five lysine- and arginine-rich candidates were select...

Tell Me How Much DNA You Have and I'll Tell You What Your Sex Is: Sex Determination by Flow Cytometry of Spiderlings of Allocosa marindia

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ABSTRACT

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Sex identification at early stages of development is of great interest for studies in evolutionary biology in many animals. Knowing the sex ratio, even more in offspring, allows testing hypotheses related to the cause of sex ratio biases in populations and species. Spiders born with a defined sex, mostly have an X1X20 sex chromosome system, but it is not possible to determine their sex phenotypically until the adult or near-adult stage. The wolf spider Allocosa marindia inhabits the sandy coast of Southern South America and shows sex role reversal. Laboratory and field studies suggest a strong bias in the sex ratio in favour of females in this species. Here, we analysed the 2C nuclear DNA content by flow cytometry in females and males of A. marindia to determine whether the difference between the sexes is enough to identify the sex of the individuals. The average 2C DNA content for females was 4.96 ± 0.036 pg and for males 4.72 ± 0.020 pg. Then, we tested the usefulness of the technique to sex A. marindia frozen spiderlings, in order to be able to decouple the collection time from the processing time. We analysed 59 spiderlings from four known females. Although we found greater variability in frozen samples, the difference in DNA content was enough to determine the sex of 54 frozen spiderlings (43 females and 11 males). Our results show a promising technique for sexing hatchlings of diplodiploid arthropods. In future studies, we will seek to sex spiderlings from a larger number of mothers to understand the causes of female bias in this species.

Bidegaray-Batista, L., N.Kacevas, F. F.Santiñaque, M.Vaio, and M.González. 2026. “Tell Me How Much DNA You Have and I'll Tell You What Your Sex Is: Sex Determination by Flow Cytometry of Spiderlings of Allocosa marindia.” Ecology and Evolution16, no. 4: e73453. https://doi.org/10.1002/ece3.73453.