Open Reading Frame brings together a selection of recent publication highlights from elsewhere in the open access ecosystem. This week we take a look at the past few weeks in biology.
Understanding the past by watching bears eat
Up in the mountains of the Spanish Pyrenees, a brown bear has just killed a deer. How will it consume the carcass? Well, most likely it will eat the viscera first, then move on to the meat around the limbs and perhaps finish off by chewing on some bones. These are the findings of new research that analysed the eating habits of Spanish brown bears; in some cases by analysing the remains, in others by setting up cameras near carcasses and watching the bears in action. Beyond gory curiosity (yes, pictures and videos are included in the paper) the findings are potentially useful to palaeontologists and archaeologists. The cause of death of skeletal remains is often determined by the pattern of bite marks on the bones. By providing a better understanding of the damage modern day bears inflict on the bones of their prey, this research should make it easier to determine if ancient bears were responsible for the deaths of discovered animal remains.
Arilla et al. PLoS One
Bacteria are often social, producing ‘public-good’ molecules that benefit all surrounding bacteria. Such systems are open to exploitation by cheats, who could benefit from the presence of such molecules without incurring the costs of actually producing them. A new study provides the first experimental demonstration of how such co-operative behaviour can persist in the face of cheats. The key is the transfer of genetic material between individual bacteria. Over time such transfers will ensure that public-good molecules preferentially benefit bacteria who also produce them, creating conditions where co-operation is favoured by natural selection. This explains why the genes that code for such molecules are so often found on mobile genetic elements. It also provides another explanation, beyond increasing genetic diversity, for the bacterial habit of swapping genes.
Dimitriu et al. PNAS
Tracking human interactions
Research of human social interactions has traditionally suffered from an overreliance on self-reported behaviours, which are notoriously unreliable. Technology offers a solution through the development of small wearable sensors that can track study participants and produce objective measurements of their behaviour. Researchers from Harvard used such “sociometers” to investigate gender differences in social interactions. The sociometers track both proximity to other participants and contain a microphone to monitor how often participants speak (although not, it should be said, the contents of their conversations). In a collaborative setting (an intensive section of a university course), women were more likely to associate with other women and were more talkative than men, especially in small groups. Conversely, in a non-collaborative setting (workers eating lunch in their break room) no such gender differences were seen. These results are consistent with the idea that women have a more interactive learning style than men.
Onnela et al. Scientific Reports
A post-mortem delayed
Paleopathologists have identified the cause of death of a man who died almost 700 years ago. The skeleton of the 50-60 year old man was discovered in a now abandoned medieval village in Italy. Based on the physical evidence, tuberculosis appeared to be the most likely cause of death. However the use of shotgun metagenomics, which allows the mass sequencing of all DNA in a sample without any predefined target, found no evidence of TB but did unexpectedly identify the genome sequence of Brucella melitensis; this seems to have been the cause of death. Today Brucella is a widespread bacterial disease of livestock which infects a number of humans every year, usually through ingestion of unpasteurised dairy products. The medieval Brucella strain identified is most closely related to modern day Italian strains, confirming that this disease has persisted in Italy over the centuries (notably this region of Italy has a long history of goat herding). The results also demonstrate the potential of shotgun metagenomics to uncover the historical emergence and evolution of other pathogens.
Kay et al. mBio
Re-wiring the brain
There is no better way to understand how neural circuits work than by changing the connections and observing the results. Difficult to do, but a team from Cambridge has been able to create synthetic synapses for the model species C.elegans, allowing them to rewire its behavioural circuits. Adding a synapse between two sensory neurons that have opposite responses to the presence of salt completely altered the worms chemotaxic response, leaving them unable to navigate through a salt gradient like normal worms. Reconfiguring neurons that mediate the response to benzaldehyde, an attractive odorant, resulted in the complete removal of the worms normal behaviour in its presence. The researchers say these techniques could potentially be used to modify mammalian brain circuits.
Rabinowitch et al. Nature Communications
Solving mankind’s problems by altering the DNA of natural populations still sounds like the stuff of science fiction, but many have suggested it could one day be reality. Lab-based engineering attempts of this sort have encountered various problems, but a new overview suggests they could be overcome by use of RNA-guided drive genes. Natural versions of these genes “drive” themselves through populations by increasing the odds that they will be inherited. Researchers suggest that the increasingly widespread use of Cas9 in genetic engineering provides a way to create a synthetic drive gene. Cas9, an enzyme naturally occurring as part of the bacterial immune system, can be programmed to ‘remember’ certain DNA sequences; when it encounters the target sequence it can either delete the gene or replace it with another. Potentially then, a Cas9 based drive gene could spread any genetic alteration we want through sexually reproducing species. It could for example be used to eradicate disease spreading insects like the mosquito or to control invasive species. Of course substantial safeguards would have to be put in place were this ever attempted, not least because it would be several years before the effects became apparent.
Esvelt et al. eLife
Written by Christopher Foote, Executive Editor for the BMC Series.