The same protein domain (ICA—green circle) mediates trimerization and self-cleavage in (A) the tail of a bacteriophage and (B) a transcription factor that drives insulation of nerves in the human brain. Image credit: Li, et al.

<p>The same protein domain (ICA—green circle) mediates trimerization and self-cleavage in (A) the tail of a bacteriophage and (B) a transcription factor that drives insulation of nerves in the human brain. Image credit: Li, et al.</p

What slows ribosomes down? The freely translating ribosome (A) was thought to be slowed by codons that need rare tRNAs (B) or by mRNA secondary structure (C). Charneski and Hurst, however, show that the dominant braking factor is the presence of positively charged amino acids (red beads) in the exit tunnel (D).

<p>What slows ribosomes down? The freely translating ribosome (A) was thought to be slowed by codons that need rare tRNAs (B) or by mRNA secondary structure (C). Charneski and Hurst, however, show that the dominant braking factor is the presence of positively charged amino acids (red beads) in the exit tunnel (D).</p

ObgE (lilac) bound to the inner surface of the large ribosomal subunit (blue), preventing its association with the small subunit (not shown).

<p><i>Image Credit: Boya Feng</i>.</p

Red LacI-mCherry and green TetR-EYFP allowed the authors to directly visualise DNA looping caused by eight lambda repressor molecules (blue) in individual living bacteria by measuring the distance between red and green spots (double-headed arrows).

<p>Red LacI-mCherry and green TetR-EYFP allowed the authors to directly visualise DNA looping caused by eight lambda repressor molecules (blue) in individual living bacteria by measuring the distance between red and green spots (double-headed arrows).</p

Most genetic studies of common diseases have been performed in populations with European ancestry; the genetic effects that they identify are progressively diluted in people from other continents.

<p>Most genetic studies of common diseases have been performed in populations with European ancestry; the genetic effects that they identify are progressively diluted in people from other continents.</p

The <i>Aspergillus</i> VosA velvet domain (beige and orange) partially superimposed on the RHD from human NF-κB (pale and dark blue) to show the structural similarity between these transcription factors from different kingdoms.

<p><i>Image Credit:</i> Fig. S8B from Ahmed et al.: PLoS Biol 11(12): e.1001750. doi:10.1371/journal.pbio.1001750.</p

Stress breeds asymmetry. In the normal situation (left-hand panel), aggregates are small and partitioned symmetrically. After thermal stress (right-hand panel), increased rates of aggregate fusion result in a smaller number of larger aggregates. By the second cell division (bottom of each panel), one cell inherits all, and is likely to die soon after.

<p>Stress breeds asymmetry. In the normal situation (left-hand panel), aggregates are small and partitioned symmetrically. After thermal stress (right-hand panel), increased rates of aggregate fusion result in a smaller number of larger aggregates. By the second cell division (bottom of each panel), one cell inherits all, and is likely to die soon after.</p

Wild-type and gender-swapped <i>Volvox</i>. Color differential interference contrast (DIC) images of <i>V. carteri</i> wild-type male (upper left), wild-type female (upper right), pseudo-female (lower left) and pseudo-male (lower right).

<p><i>Image credit: Sa Geng and James Umen.</i></p

When good assays turn bad.

<p>a) A ribosome (dark purple) runs along a normal transcript (wiggly orange/green line), translating it into protein (orange circle – upstream region; green sun – luciferase), which then emits light in the assay. b) A nonsense mutation (red hexagon) stops most of the ribosomes in the middle of the transcript, producing a truncated, non-luminescent protein (orange circle), with very few ribosomes (pale purple) reading through to give a dim luciferase light signal in the assay. The drug (blue triangle) has no effect. c) The dream scenario—a drug interacts with the ribosome, causing it to read through, generating plenty of luciferase and light. d) The potential explanation for the discovery of PTC124—the drug instead interacts with the luciferase molecules, stabilizing them (large green sun) and giving a spurious light signal.</p

A mathematical model captures many of the complexities of HIV's relationship with the human immune system, revealing that sometimes the benefits of detection by T_H cells can outweigh the costs of detection by cytotoxic T cells (CTLs).

<p>A mathematical model captures many of the complexities of HIV's relationship with the human immune system, revealing that sometimes the benefits of detection by T_H cells can outweigh the costs of detection by cytotoxic T cells (CTLs).</p