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This Week in Science: Jan 16, 2009

In this week's issue of Science, authors from the Stanford Center for Biomedical Ethics write a perspective on the 2006 Genomics and Personalized Medicine Act (GPMA). When S.3822 was revised and reintroduced to Congress in 2008 as S.976, the entire section of "Race, Genomics, and Health" and its provisions were deleted from the bill, say the authors. "An opportunity to provide clarity and leadership on critical issues of human genetic variation from 'bench' to 'bedside' is lost in the current GPMA," which they argue needs to be directly addressed for personalized medicine to avoid "an emerging landscape of race-based therapeutics."

Scientists have looked into natural variation in bacterial pathogen resistance in C. elegans. They used quantitative genetic analysis to find that susceptibility difference between the wild-type strain N2 and the wild isolate CB4856 is caused by a polymorphism in the npr-1 gene, which encodes a homolog of the mammalian neuropeptide Y receptor.

Researchers compared the genomes of two Japanese killifish in an attempt to study how transcription and chromatin structure contribute to the evolution of DNA sequence. They compared two strains, Hd-rR and HNI, and mapped about 37.3 million nucleosome cores from Hd-rR blastulae and 11,654 representative transcription start sites from six embryonic stages, finding an approximately 200-base pair periodic pattern of genetic variation downstream of transcription start sites. "Although the action of purifying selection at many sites within linkers cannot be excluded on the basis of current data, the evidence seems to favor chromatin-mediated mutational bias as the main cause of periodic divergence patterns around consistently positioned nucleosomes," says a related Perspective.

Scientists have used symbiotic bacteria to study genome degradation and reduction. They sequenced the genomes of seven strains of the bacteria Buchnera aphidicola, an endosymbiont of pea aphids, to find a high mutation rate of base substitutions, as well as a high rate of small insertions and deletions associated with DNA homopolymers and occasional larger deletions. "Our results provide a general model for the stepwise process leading to genome reduction," they write in the abstract.

The Scan

Pig Organ Transplants Considered

The Wall Street Journal reports that the US Food and Drug Administration may soon allow clinical trials that involve transplanting pig organs into humans.

'Poo-Bank' Proposal

Harvard Medical School researchers suggest people should bank stool samples when they are young to transplant when they later develop age-related diseases.

Spurred to Develop Again

New Scientist reports that researchers may have uncovered why about 60 percent of in vitro fertilization embryos stop developing.

Science Papers Examine Breast Milk Cell Populations, Cerebral Cortex Cellular Diversity, Micronesia Population History

In Science this week: unique cell populations found within breast milk, 100 transcriptionally distinct cell populations uncovered in the cerebral cortex, and more.