A conserved female-specific larval requirement for MtnB function facilitates sex separation in multiple species of disease vector mosquitoes

Background Clusters of sex-specific loci are predicted to shape the boundaries of the M/m sex-determination locus of the dengue vector mosquito Aedes aegypti, but the identities of these genes are not known. Identification and characterization of these loci could promote a better understanding of mosquito sex chromosome evolution and lead to the elucidation of new strategies for male mosquito sex separation, a requirement for several emerging mosquito population control strategies that are dependent on the mass rearing and release of male mosquitoes. This investigation revealed that the methylthioribulose-1-phosphate dehydratase (MtnB) gene, which resides adjacent to the M/m locus and encodes an evolutionarily conserved component of the methionine salvage pathway, is required for survival of female larvae. Results Larval consumption of Saccharomyces cerevisiae (yeast) strains engineered to express interfering RNA corresponding to MtnB resulted in target gene silencing and significant female death, yet had no impact on A. aegypti male survival or fitness. Integration of the yeast larvicides into mass culturing protocols permitted scaled production of fit adult male mosquitoes. Moreover, silencing MtnB orthologs in Aedes albopictus, Anopheles gambiae, and Culex quinquefasciatus revealed a conserved female-specific larval requirement for MtnB among different species of mosquitoes. Conclusions The results of this investigation, which may have important implications for the study of mosquito sex chromosome evolution, indicate that silencing MtnB can facilitate sex separation in multiple species of disease vector insects. Graphical Abstract

Title IX

Title IX, the federal civil rights law that prohibits sex discrimination in education, is well known for transforming girls’ and women’s sports. Since its early history, Title IX has embraced a system of sex segregation in sports. However, Title IX’s “separate but equal” regime is increasingly being challenged by feminists who argue that it has not done enough to eliminate gender disparities and inequities in sport and is fundamentally incompatible with the inclusion and fair treatment of transgender and nonbinary athletes. The first two sections of this article trace the history of Title IX as it has been applied to sports. The article then canvasses the feminist arguments for and against sex segregation in sports and makes the case that a regime of strict sex separation is no longer the best strategy for assuring girls’ and women’s success in sports and dislodging pernicious stereotypes of women’s inferior athleticism.

A novel drug-inducible sex-separation technique for insects

ABSTRACTLarge sterile male releases are the gold standard for most insect population control methods and thus precise sex sorting is essential to the success of these technologies. Sex sorting is especially important for mosquito control because female mosquitoes bite and transmit diseases. However, current methods for insect sex sorting have deficiencies as they are error prone, low throughput, expensive, reduce male fitness, or lack cross species adaptability. Here we describe a novel drug-inducible system for insect sex-separation that demonstrates proof-of-principle for positive sex selection in D. melanogaster. The system exploits the toxicity of commonly used broad-spectrum antibiotics geneticin and puromycin and rescues only one sex. Sex specific rescue is achieved by inserting the sex-specific introns, TraF and DsxM, into the coding sequence of antibiotic resistance genes, NeoR or PuroR. We engineer a dual sex-sorter gene cassette and demonstrate sex specific, constitutive expression of NeoR and PuroR proteins in females and males, respectively. When raised on geneticin supplements, this sex-sorter line established 100% positive selection for female progeny, while the food supplemented with puromycin generated 100% male progeny. This system is 100% efficient and operates at remarkably low fitness costs in D. melanogaster. Since the described system exploits a conserved sex-specific splicing mechanism and reagents, which are active in many insects, it has the potential to be adaptable to insect species of medical and agricultural importance.GRAPHIC ABSTRACT