Dioecy and sex chromosomes almost certainly evolved from ancestral hermaphrodites that only possessed autosomes. There is a growing body of evidence that genes for female or male function were then epigenetically suppressed in some of these hermaphrodites, creating the first males or females and nascent sex chromosomes. The incipient sex-determining epigenetic signals, such as cytosine methylat...

The diploid number in Rhodnius is 22 in both sexes. At hatching the fat-body cells are tetraploid, with a few octoploid. This polyploidy is presumed to arise by endomitosis in the egg. In the fully nourished insect this state persists throughout life; and occasional i6« and 32W nuclei occur. Whether these arise by endomitosis or by nuclear fusion has not been established. In extreme starvation ...

To study the evolutionary effects of polyploidy on plant gene functions, we analyzed functional genomics data for a large number of duplicated gene pairs formed by ancient polyploidy events in Arabidopsis thaliana. Genes retained in duplicate are not distributed evenly among Gene Ontology or Munich Information Center for Protein Sequences functional categories, which indicates a nonrandom proce...

The ERCC1 gene is essential for the repair of UV-induced DNA damage. Unlike most genes in the nucleotide excision repair (NER) pathway, ERCC1 is also involved in recombinational repair. Perhaps for this reason, ERCC1 knockout mice are not a model for the human NER deficiency disorder, xeroderma pigmentosum. Instead, ERCC1 null mice are severely runted and die before weaning from liver failure w...

Whole-genome duplication (WGD) doubles the DNA content in the nucleus and leads to polyploidy. In whole-organism polyploids, WGD has been implicated in adaptability and the evolution of increased genome complexity, but polyploidy can also arise in somatic cells of otherwise diploid plants and animals, where it plays important roles in development and likely environmental responses. As with whol...

Many crops are polyploid or have a ancestry. Recent phylogenetic analyses found that polyploidy often preceded the domestication of crop plants. One explanation for this observation is increased genetic diversity following may been important during strong artificial selection occurs domestication. In order to test connection between and polyploidy, we identified examined candidate genes associa...