Identification of a trafficking motif involved in the stabilization and polarization of P2X receptors

Extracellular ATP-gated channels (P2X receptors) define the third major family of ionotropic receptors, and they are expressed widely in nerve cells, muscles, and endocrine and exocrine glands. P2X subunits have two membrane-spanning domains, and a receptor is thought to be formed by oligomerization of three subunits. We have identified a conserved motif in the cytoplasmic C termini of P2X subunits that is necessary for their surface expression; mutations in this motif result in a marked reduction of the receptors at the plasma membrane because of a rapid internalization. Transfer of the motif to a reporter protein (CD(4)) enhances the surface expression of the chimera, indicating that this motif is likely involved in the stabilization of P2X receptor at the cell surface. In neurons, mutated P2X(2) subunits showed reduced membrane expression and an altered axodendritic distribution. This motif is also present in intracellular regions of other membrane proteins, such as in the third intracellular loop of some G protein-coupled receptors, suggesting that it might be involve in their cellular stabilization and polarization.     

The elimination of fox rabies from Europe: determinants of success and lessons for the future

Despite perceived challenges to controlling an infectious disease in wildlife, oral rabies vaccination (ORV) of foxes has proved a remarkably successful tool and a prime example of a sophisticated strategy to eliminate disease from wildlife reservoirs. During the past three decades, the implementation of ORV programmes in 24 countries has led to the elimination of fox-mediated rabies from vast areas of Western and Central Europe. In this study, we evaluated the efficiency of 22 European ORV programmes between 1978 and 2010. During this period an area of almost 1.9 million km² was targeted at least once with vaccine baits, with control taking between 5 and 26 years depending upon the country. We examined factors influencing effort required both to control and eliminate fox rabies as well as cost-related issues of these programmes. The proportion of land area ever affected by rabies and an index capturing the size and overlap of successive ORV campaigns were identified as factors having statistically significant effects on the number of campaigns required to both control and eliminate rabies. Repeat comprehensive campaigns that are wholly overlapping much more rapidly eliminate infection and are less costly in the long term. Disproportionally greater effort is required in the final phase of an ORV programme, with a median of 11 additional campaigns required to eliminate disease once incidence has been reduced by 90 per cent. If successive ORV campaigns span the entire affected area, rabies will be eliminated more rapidly than if campaigns are implemented in a less comprehensive manner, therefore reducing ORV expenditure in the longer term. These findings should help improve the planning and implementation of ORV programmes, and facilitate future decision-making by veterinary authorities and policy-makers.     

Structural messenger RNA contains cytokeratin polymerization and depolymerization signals

We have previously shown that VegT mRNA plays a structural (translation-independent) role in the organization of the cytokeratin cytoskeleton in Xenopus oocytes. The depletion of VegT mRNA causes the fragmentation of the cytokeratin network in the vegetal cortex of Xenopus oocytes. This effect can be rescued by the injection of synthetic VegT RNA into the oocyte. Here, we show that the structural function of VegT mRNA in Xenopus oocyte depends on its combinatory signals for the induction or facilitation and for the maintenance of the depolymerization vs. polymerization status of cytokeratin filaments and that the 300-nucleotide fragment of VegT RNA isolated from the context of the entire molecule induces and maintains the depolymerization of cytokeratin filaments when injected into Xenopus oocytes. A computational analysis of three homologous Xenopus VegT mRNAs has revealed the presence, within this 300-nucleotide region, of a conserved base-pairing (hairpin) configuration that might function in RNA/protein interactions.     

Evaluation of a high-density oligonucleotide array for characterization of grlA, grlB, gyrA and gyrB mutations in fluoroquinolone resistant Staphylococcus aureus isolates

Using high-density oligonucleotide array technology, 30 Staphylococcus aureus strains were studied for the presence of mutations in genes involved in fluoroquinolone resistance: grlA, gyrA, grlB and gyrB. For the two most important genes, gyrA and grlA, correlation with sequencing reached 95.1%. If all genes were considered, correlation was 88.8%.     

Cooperative prey-retrieving in the ant Cataglyphis floricola: an unusual short-distance recruitment

Cataglyphis ants are mostly scavengers adapted to forage individually in arid environments. Although they are widely thought to have lost the capacity of recruitment, we provide evidence that C. floricola foragers that find a large prey near their nest are able to solicit the help of nestmates to carry it cooperatively. After discovering a non-transportable prey, these ants readily return to their nest and stimulate the exit of several recruits. This rudimentary form of recruitment, which is absent in the sympatric species C. rosenhaueri, is only employed when the prey is sufficiently close to the nest entrance (<1 m) and does not allow the food location to be communicated. Instead, C. floricola recruits search for the prey in all directions until they discover it and transport it cooperatively to their nest.     

Food- and temperature-dependent function of moulting rate in copepods: An example of parameterization for population dynamics models

The effects of temperature and food concentration on moultingrates in copepods were studied. The distribution of transferrates in different stages of Euterpina acuhfrons in differenttemperature and food concentrations were simulated using a processmodel. These distributions were fitted by an appropriate asymmetricalprobability distribution: the gamma density function (GDF).A parameterization of moulting rates established a continuousrelationship between parameters of GDF, and the two externalfactors, temperature and food concentration. This function canalso represent the frequency distribution of successive developmentalstages in a cohort. Two examples of such representation aregiven, using literature data.