The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25–50%) than euchromatic reference regions (3–11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11–27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4–3.6 vs. 8.4–8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu.

Although north Indian women experienced various symptoms at menopause, they largely ignored these, while welcoming the freedom from menstruation-related worries.

No abstract

No abstract

Heat stress is a major productivity lowering factor in wheat. Wild progenitor species offer a wide spectrum of adaptation traits and can serve as valuable donors of stress tolerance. In the present study, genetic variation in 129 accessions of Aegilops tauschii Coss., the D genome donor of wheat, was evaluated for two heat tolerance related traits viz., cell membrane stability (CMS) and TTC (2,3,5-Triphenyl tetrazolium chloride) based cell viability. Cell membrane stability in the Ae. tauschii accessions at vegetative stage ranged from 15.24 to 80.39%. Nineteen Ae. tauschii accessions were superior to the tolerant bread wheat control (C 273). At anthesis stage a similar spectrum of variation was observed with twenty three accessions showing higher cell membrane stability than C 273. The average CMS level of entire germplasm set at anthesis (47.61%) was lower than at vegetative stage (58.89%). Clear genotypic differences were also observed for TTC based cell viability test. Ae. tauschii accessions displayed a range from 18.73 to 84.39% with eight genotypes excelling over tolerant bread wheat. Correlation of CMS values recorded at two stages was significant but of low predictive value (r 2 = 0.137). Similarly significant but moderate correlation was obtained between CMS and TTC test (r 2 = 0.325). Consequently all the three parameters were used to derive a cell thermotolerance index which was in turn used to identify ten tolerant Ae. tauschii genotypes. The identified accessions were re-evaluated for 1 more year and the three parameters viz., CMS at vegetative (r 2 = 0.954) and anthesis stage (r 2 = 0.932) and TTC cell viability at vegetative stage (r 2 = 0.888) showed high correlation Strategy for use of identified accessions as donors is discussed.