Institute of Pharmaceutical Sciences researchers used a combination of affinity purification and microarrays to study the translational status of every mRNA in S. cerevisiae. Comparing changes in total mRNA levels with ribosome associations, which they call the translatome, they found that severe stress affected both RNA and translatome levels by about 15 percent, whereas mild stress only changed levels by about 1 percent. "These networks are preferentially activated for rapid adaptation of cells to minor environmental perturbations," they write in PLoS Biology.
Phil Green at the University of Washington led work studying natural selection in hominid evolution. In a paper in PLoS Genetics, his team looked at sequence changes among five primate species relative to the locations of conserved features, finding that "neutral sequence diversity in human and ancestral hominid populations is substantially reduced near such features," and that average selection is much stronger on protein-coding conserved features than non-exonic ones.
Scientists have concluded that "present databases are not capable of comprehensively retrieving all known metabolites," in work published this week in PLoS One. In scanning databases for both known rice metabolites and computationally derived ones for two sequenced rice variants, oryza japonica and oryza indica, they found that often, "genuine rice metabolites were retrieved together with non-metabolite database entries such as pesticides." Overlaps from database compound lists were hard to compare because structures were either not encoded in machine-readable format or compound identifiers were not cross-referenced between databases, they say.
Also in PLoS One this week, scientists at NYU examined the diversity of 23S rRNA prokaryotic genes, finding that there was "tight ribosomal constraints" on individual 23S rRNA genes within a genome. Looking at 184 species, they found 113 genomes to harbor diversity, eight species showing significant intragenomic variation, and five out of eight showing that changes in primary structure have little effect on secondary structure.