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Kumar S.,SKA Institution of Research | Kumar S.,National Institute of Plant Genome Research | Kumari R.,SKA Institution of Research | Kumari R.,National Institute of Plant Genome Research | Sharma V.,SKA Institution of Research
Journal of Genetics | Year: 2014

Dioecy (separate male and female individuals) ensures outcrossing and is more prevalent in animals than in plants. Although it is common in bryophytes and gymnosperms, only 5% of angiosperms are dioecious. In dioecious higher plants, flowers borne on male and female individuals are, respectively deficient in functional gynoecium and roecium. Dioecy is inherited via three sex chromosome systems: XX/XY, XX/X0 and WZ/ZZ, such that XX or WZ is female and XY, X0 or ZZ are males. The XX/XY system generates the rarer XX/X0 and WZ/ZZ systems. An autosome pair begets XY chromosomes. A recessive loss-of-androecium mutation (ana) creates X chromosome and a dominant gynoecium-suppressing (GYS) mutation creates Y chromosome. The ana/ANA and gys/GYS loci are in the sex-determining region (SDR) of the XY pair. Accumulation of inversions, deleterious mutations and repeat elements, especially transposons, in the SDR of Y suppresses recombination between X and Y in SDR, making Y labile and increasingly degenerate and heteromorphic from X. Continued recombination between X and Y in their pseudoautosomal region located at the ends of chromosomal arms allows survival of the degenerated Y and of the species. Dioecy is presumably a component of the evolutionary cycle for the origin of new species. Inbred hermaphrodite species assume dioecy. Later they suffer degenerate-Y-led population regression. Cross-hybridization between such extinguishing species and heterologous species, followed by genome duplication of segregants from hybrids, give rise to new species. © 2014 Indian Academy of Sciences.

Kumar S.,SKA Institution of Research | Kumari R.,National Institute of Plant Genome Research
Proceedings of the Indian National Science Academy | Year: 2015

Malaria is world's predominant morbidity and mortality causing infectious disease. Diagnosis of Plasmodium infections in febrile persons, residing in malaria endemic areas, is a pre-requisite for proper malarial treatment. The presently available dipstick antigen detection (RDT), microscopic (Giemsa stained smear on slide) and polymerase chain reaction (PCR) tests of malaria are poor in sensitivity, time consuming, and expensive. Recently developed rolling circle enhanced enzyme activity detection (REEAD)- and micromagnetic resonance reflaxometric (MMR)- test are amenable to deployment in field conditions and are highly accurate; and cost- and time-effective. The properties of all three conventional and two new malaria tests have been compared here and have been shown to be complementary for usage, under hospital laboratory and field conditions. © Printed in India.

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