Isozyme Diversity in Indian Primitive Maize Landraces

Polymorphism for peroxidase, esterase and acid phosphatase Isozymes in pollen grains of major Indian maize land races known as ‘Sikkim primitives’ were studied and compared with primitive races of maize of Mexican origin and five species of teosinte, Coix lacryma-jobi, Chionachne koenigii and Sorghum bicolor. The isozyme patterns and the resulting dendrograms revealed similarities in primitive Indian maize landraces from Northeastern Himalayan region and Nal-Tel an ancient indigenous race of Mexico. Further, the Asiatic taxa of Maydeae, C. lacryma-jobi and Ch. koenigii differed widely from each other and also from the Zea spp. Presence of greater diversity among the Indian maize collections was also evident from the present analysis.     

Sex ratio trajectory in mouse

Skewing of the sex ratio towards males occurs in humans. The possible explanation for excess male births could be a preference for Y-bearing sperm at fertilization and/or selective elimination of female embryos during pregnancy. In this study, we have tested the sex ratio in the preimplantation embryo (2–3 cells stage/closest possible primary sex ratio), the post-implantation embryo (day E7.5), and at birth (secondary sex ratio) on a homogenous (genetic, environmental, and dietary) population of mice to ascertain the biological reason i.e., male preference at fertilization or female elimination during pregnancy or both. Primary sex ratio on early preimplantation embryos (2–3 cells stage) was studied on 598 embryos and secondary sex ratio (at birth) on 721 pups using PCR-based sexing (both X & Y chromosome-specific) besides sex ratio of 80 post-implantation embryos (day E7.5). We have also investigated whether the fat content (high & low) of the diet affects the sex ratio. We observed a skewed sex ratio (more female) in preimplantation embryos (0.436; 95 % CI 0.39, 0.48), and post-implantation embryos (0.462; 95 % CI 0.35, 0.57) but reverse skewing (more male) at birth (0.539; 95 % CI 0.5, 0.58). We also observed that high-fat diet promoted male sex ratio at birth (0.657; 95 % CI 0.57, 0.74) whereas a low-fat diet had the opposite effect (0.46; 95 % CI 0.36, 0.56) but no effect at fertilization (2–3 cells stage embryos). This indicates selective elimination of female embryo and fetus throughout pregnancy in mice, more so with a high-fat diet.