Skip to main content
Premium Trial:

Request an Annual Quote

This Week in PNAS: Jan 4, 2011

In this week's PNAS Early Edition, investigators describe the intestinal microbiome of a premature infant, in which they characterized "strain-level genomic divergence during the first three weeks of life." During colonoziation, the team identified three compositional phases, and in addition, genotypic variation that could be "responsible for divergent strain ecologies, including hotspots of sequence variation in regulatory genes and intergenic regions, and in genes involved in transport, flagellar biosynthesis, substrate metabolism, and host colonization, as well as differences in the complements of these genes." The authors suggest that their study provides framework for further community genomics investigations to determine the "medically relevant strain and species population dynamics."

Also in PNAS this week, an international research team reports that "cystic leukoencephalopathy is a lysosomal storage disorder in which rRNA is the best candidate for the noxious storage material." The investigators found that the loss of rnaset2 in mutant zebrafish leads to the "accumulation of undigested rRNA within lysosomes within neurons of the brain." Because RNASET2 mutation is associated with leukoencephalopathy in humans, the team proposes rnaset2 mutant zebrafish as a model for familial cystic leukoencephalopathy.

Razika Hussein and Han Lim at the University of California, Berkeley, show that the Hfq protein "can be a limiting factor for sRNA activity and that it can be easily depleted, causing disruption of the sRNA network" in vivo. By coordinating the transcription of sRNAs with their targets, Hussein and Lim saw reduced Hfq sequestration. "… the limited availability of Hfq results in a highly interdependent sRNA network, wherein the activity of each sRNA depends on the activity of the other sRNAs and target mRNAs in the network," they conclude.

The University of Arizona's Etienne Rajon and Joanna Masel discuss the "evolution of molecular error rates and the consequences for evolvability" in PNAS this week. More specifically, Rajon and Masel say that "for a large range of realistic intermediate population sizes, the evolutionary dynamics are bistable" and a local solution which ensures that each "error has a relatively benign effect … facilitates the genetic assimilation of cryptic genetic variation and therefore substantially increases evolvability."

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.