In this week's Nature, a team led by National Institutes of Health scientists report new data on the fundamental genome-folding principles that govern higher-order chromosome organization required for coordinating nuclear functions. They conducted a genome-wide chromatin conformation capture analysis to examine the organization of the genome of the model organism Schizosaccharomyces pombe, and found that globules are a prominent feature of local chromatin organization. Further, globules require cohesin and are a basic element of chromosome arm architecture, distinct from cohesin-dependent long-range loop interactions between gene regulatory elements in higher eukaryotes. Heterochromatin was also shown to mediate chromatin fiber compaction at centromeres and promote prominent inter-arm interactions within centromere-proximal regions, setting structural constraints for proper genome organization. Loss of heterochromatin, meanwhile, was found to ease these constraints, causing an increase in intra-and inter-chromosomal interactions.
And in Nature Genetics, Chinese investigators publish the discovery of genetic regions associated with selective breeding in tomatoes. By sequencing the genomes of 360 tomato varieties, they found a group whose genetic makeup was between wild tomato plants and ones that have been breed for commercial purposes. Using this group, that found that about 8 percent of the tomato genome is involved in domestication, and about 7 percent of the genome that was selected for during the later improvement phase. About one-fifth of these regions overlapped. GenomeWeb Daily News has more on this study here.