Journal of Biology最新文献

Vast supercolonies of interconnected nests formed by unicolonial ant species are the largest cooperative groups of animals known. Research published recently in BMC Evolutionary Biology reveals that a supercolony can be more genetically structured than previously thought, comprising several extended families. Surprisingly, the families coexist peacefully, even though they seem to recognize each other as non-kin.

Background: Most odors are perceived to have the same quality over a large concentration range, but the neural mechanisms that permit concentration-invariant olfactory perception are unknown. In larvae of the vinegar fly Drosophila melanogaster, odors are sensed by an array of 25 odorant receptors expressed in 21 olfactory sensory neurons (OSNs). We investigated how subsets of larval OSNs with overlapping but distinct response properties cooperate to mediate perception of a given odorant across a range of concentrations.

Results: Using calcium imaging, we found that ethyl butyrate, an ester perceived by humans as fruity, activated three OSNs with response thresholds that varied across three orders of magnitude. Whereas wild-type larvae were strongly attracted by this odor across a 500-fold range of concentration, individuals with only a single functional OSN showed attraction across a narrower concentration range corresponding to the sensitivity of each ethyl butyrate-tuned OSN. To clarify how the information carried by different OSNs is integrated by the olfactory system, we characterized the response properties of local inhibitory interneurons and projection neurons in the antennal lobe. Local interneurons only responded to high ethyl butyrate concentrations upon summed activation of at least two OSNs. Projection neurons showed a reduced response to odors when summed input from two OSNs impinged on the circuit compared to when there was only a single functional OSN.

Conclusions: Our results show that increasing odor concentrations induce progressive activation of concentration-tuned olfactory sensory neurons and concomitant recruitment of inhibitory local interneurons. We propose that the interplay of combinatorial OSN input and local interneuron activation allows animals to remain sensitive to odors across a large range of stimulus intensities.

The relative sizes of parts of an organism frequently depend on the absolute size of the individual, a relationship that is generally described by power laws. I show here that these power laws are a consequence of the way evolution operates.

A recent study in BMC Evolutionary Biology shows that many of the open reading frames in mammalian Hox genes are more conserved than expected on the basis of their protein sequence. The presence of highly conserved DNA elements is thus not confined to the noncoding DNA in neighboring regions but clearly overlaps with coding sequences. These findings support an emerging view that gene regulatory and coding sequences are likely to be more intermingled than once believed.

Good early training of graduate students and postdocs is needed to prevent them turning into future generations of manuscript-savaging reviewers. How can we intercalate typical papers into our training?

Molecular techniques for identifying pathogens associated with cancer continue to be developed, including one reported recently in BMC Medical Genomics. Identifying a causal infectious agent helps in understanding the biology of these cancers and can lead ultimately to the development of antimicrobial drugs and vaccines for their treatment and prevention.

How vernalization - exposure to a period of cold - induces flowering in Arabidopsis has been intensively investigated at the genetic and moleular levels. Recent papers, including one in BMC Plant Biology, shed light on changes in gene regulation that occur on vernalization in cereals.