Open Reading Frame: shark decline, viral spread to honeybees & light harvesting

Posted by Biome on 24th January 2014 - 0 Comments


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.

 

Viruses exploit cell machinery to get a push in the right direction
Cell stability is maintained by scaffold-like structures known as the cytoskeleton. A component of this is actin, the building blocks of microfilaments that not only help keep a cell’s shape but also act as tightropes along which motor proteins can move. It is already known that these actin filaments can be exploited by some microbial pathogens in order to facilitate infection of neighbouring cells, and for the first time this has now been demonstrated in a virus. Using a technique called cryo-electromagnetic microscopy, exploitation of this filament network has been visualised and modelled using an insect pathogen called a Baculovirus. This virus uses the filaments to propel itself between cells by riding a wave of filament growth, leaving a fishbone-shaped ‘comet tail’ of actin in its wake. This is the first time this has been demonstrated in such a small infective agent, and will aid the understanding of how pathogens exploit intracellular machinery to propagate infection.
Mueller et al. PLoS Biology

 

For a quarter of the world’s sharks, it is no longer safe to be in the water
A systematic analysis of the extinction risk currently posed to the global distribution of sharks and rays finds that one in four species are threatened with extinction according to IUCN (International Union for Conservation of Nature) Red List criteria. In collaboration with over 300 scientists from across the globe, life history and distribution data was collated from more than 1000 species in order to identify specific hotspots of greatest conservation concern. The global trade in shark fins in particular presents significant concern, since its growth among Asian countries is still largely unregulated, whilst the Indo-Pacific Biodiversity Triangle and Mediterranean sea are also highlighted due to widespread overfishing and poor management of fish stocks.
Dulvy et al. eLife

 

Pathogenic virus spreads its wings from plants to bees
A virus that normally infects a range of economically important crop plants has now been found to infect an economically important animal – the honeybee. Honeybees act as vectors for the spread of tobacco ringspot virus among crops like soybean, spreading the virus from infected plants to healthy plants as they gather pollen. However, this is the first time that the virus has been recorded replicating within the body of an insect, eventually producing infectious particles called virions that spread throughout the host body. The same strain of virus was also identified in the ecto-parasitic honeybee mite Varroa destructor which, together with those isolated from honeybees and honeybee pollen, form a separate evolutionary group to those isolated only from plants – suggesting a common origin from a single ancestral strain that made the leap between the two host kingdoms. Presence of viral infection in bees was also associated with collapse of colonies during the winter period, although the authors caution that this is only the first step in establishing whether there may be a direct causal link between the two.
Li et al. mBio

 

Reading between the lines of medical research coverage in the media
Newspapers are more likely to give coverage to medical research articles that use weaker methodology. By comparing the scientific quality of studies that were given coverage in the top five national newspapers circulating in the US with those in the top five clinical journals by impact factor, researchers find that those covered in the media were more likely to present results from observational studies than more robust randomised controlled trials. Of these observational studies, the ones covered in the media also had significantly smaller sample sizes. Although the authors acknowledge that these two outlets may serve differing purposes, they argue this raises important questions about the public perception of progress in medicine.
Selvaraj et al. PLoS One

 

Locust genome is twice the size of humans
The first draft genome of the migratory locust has revealed it to be the largest of any animal sequenced so far, at 6.5 billion base pairs – more than twice the size of the human genome. Compared to other insects species, the rate of DNA deletions is also very low, which could explain how the genome came to be so large. As well as being a  major pest of crops throughout the world, locusts are remarkable in that they exhibit a morphological change between a flightless and a migratory form when population size increases, leading to swarming behaviour. By investigating epigenetic changes that take place during the transition between these phases, this research could also help identify key genetic targets that could be exploited to prevent swarming, as well as pinpoint genes that might be most susceptible as targets of pesticides.
Wang et al. Nature Communications

 

Viewing the light harvest in plant cells
Thylakoids are disc-shaped structures in plant cell chloroplasts where light-dependent photosynthesis takes place. The main site for these photosynthetic reactions is in the disc’s membrane, where pigment-containing antennal proteins harvest light of different wavelengths and redistribute the energy they absorb into different photosystems to maximise efficiency and protect the system from excess energy. As a result, thylakoid membranes require flexibility in protein organisation in order to cope with changing light conditions. This can prove difficult to study, since the wavelength of visible light presents a challenge for microscopy under live conditions. However, the moss Physcomitrella patens contains macrochloroplast structures that are more than 10 times larger than normal chloroplasts, enabling a team of researchers from Japan to track this flexible re-organisation of proteins by novel time-lapse imaging techniques. They find that while the thylakoid membranes retain flexibility in their structures to allow dynamic re-organisation to happen, it is the stacks of thylakoids called grana that maintain the overall structural integrity of the system.
Iwai et al. Scientific Reports

 

Written by Simon Harold, Senior Executive Editor for the BMC Series.