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This Week in Science : Apr 29, 2011

In a paper published online in advance in Science this week, researchers at Northwestern University and at Pennsylvania State University report the "structural basis for methyl transfer by a radical SAM enzyme." By studying crystal structures for the radical SAM enzyme RlmN — both with and without SAM — the team describes how "residue Cys 355 is S-methylated and located proximal to the SAM methyl group, suggesting that SAM involved in the initial methyl transfer binds at the same site." Furthermore, the team writes, RlmN harnesses "the two most important reactivities of SAM within a single site" in order to accomplish its complex reaction.

In this week's issue, an international team led by investigators at the University of Southern California assesses, among other things, expression signatures in a mouse model to identify "self-organizing and stochastic behaviors during the regeneration of hair stem cells." The team shows that as a hair follicle "progresses through cycling stages by continuous integration of inputs from intrinsic follicular and extrinsic environmental signals based on universal patterning principles," WNT/bone morphogenetic protein activator/inhibitor pair signaling is "co-opted to mediate interactions among follicles in the population." Overall, the team says that because relative activator/inhibitor strengths are easily modulated, hair stem cell regeneration is "robust and versatile."

Science's Jocelyn Kaiser this week profiles outgoing-National Institute of General Medical Sciences Director Jeremy Berg, who discusses his recent criticisms of the National Institutes of Health's decision to dissolve its National Center for Research Resources. "Berg's ongoing battle to defend NIH's NCRR has burnished his image among many scientists who were already fans," Kaiser says. Indeed, one such scientist is Keith Yamamoto of the University of California, San Francisco, who tells Science that he thinks Berg "was absolutely correct," in his objections to NIH Director Francis Collins' decision to abolish NCRR. "I admire his courage," Yamamoto says of Berg. Kaiser says that before leaving NIGMS in June — at which time he will join the University of Pittsburgh faculty — Berg has a few items left on his plate. Among other things, she says, he'd like to review the institute's training programs, and how well peer-review scores assigned to NIH grants predict performance.

Over in Science Translational Medicine, NIH Chemical Genomics Center Director Christopher Austin and his colleagues announce their launch of the NCGC Pharmaceutical Collection — "a definitive, complete, and non-redundant list of all approved molecular entities as a freely available electronic resource and a physical collection of small molecules amenable to high-throughput screening" — which they hope will enable drug repurposing efforts, particularly those related to rare and neglected diseases.

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.