Much of the Y chromosome consists of large palindromic arrays harboring genes that are critical for spermatogenesis. In this issue, Lange et al. (2009) show that although gene conversion within these arrays maintains their integrity, it also permits rare unequal sister chromatid-exchange events within palindromes that create unstable dicentric chromosomes, resulting in infertility, sex reversal...

Meiotic exchange occurs preferentially between homologous chromatids, in contrast to mitotic recombination, which occurs primarily between sister chromatids. To identify functions that direct meiotic recombination events to homologues, we screened for mutants exhibiting an increase in meiotic unequal sister-chromatid recombination (SCR). The msc (meiotic sister-chromatid recombination) mutants ...

background & aim: considering the inevitable side effects of chemical drugs, nowadays, herbal medicine has gained a special importance. cinnamon of lauraceae family, is commonly used as a food spice and medicine. it is famous to be, antimicrobial, anti-oxidant, anti-diabetic, anti-viral, and antispastic. it also prevents abdominal bloating, increases sweating and uterus muscle constrictions...

In all eukaryotes, the ribosomal RNA genes are stably inherited redundant elements. In Drosophila melanogaster, the presence of a Ybb(-) chromosome in males, or the maternal presence of the Ribosomal exchange (Rex) element, induces magnification: a heritable increase of rDNA copy number. To date, several alternative classes of mechanisms have been proposed for magnification: in situ replication...

A positive selection system for intrachromosomal recombination in Saccharomyces cerevisiae has been developed. This was achieved by integration of a plasmid containing an internal fragment of the HIS3 gene into its chromosomal location. This resulted in two copies of the HIS3 gene one with a terminal deletion at the 3' end and the other with a terminal deletion at the 5' end. Reversion of the g...

This study tested three hypotheses derived from the application of socioemotional selectivity theory and exchange theory to the exchange of emotional support with age and its relationship with positive and negative affect by age. Data are from the Midlife in the United States study of 3,032 U.S. adults between the ages of 25 and 74. The social contact hypothesis predicts that hours of emotional...