Autocrine activation of adenosine A1 receptors blocks D1A but not D1B dopamine receptor desensitization

Adenosine is known to modulate dopamine responses in several brain areas. Here, we show that tonic activation of adenosine receptors is able to impede desensitization of D1 dopamine receptors. As measured by cAMP accumulation in transfected COS-7 cells, long-term exposure to dopamine agonists promoted desensitization of D1B receptor but not that of D1A receptor. The inability of D1A receptor to desensitize was a result of the adenosine present in culture medium acting through activation of adenosine A1 receptors. Cell incubation with either adenosine deaminase, CGS-15943, a generic adenosine receptor antagonist, or the A1 antagonist DPCPX restored the long-term desensitization time-course of D1A receptors. In Ltk cells stably expressing A1 adenosine receptors and D1A dopamine receptors, pre-treatment of cells with R(-)-PIA, a full A1 receptor agonist, did not significantly inhibit the acute increase in cAMP levels induced by D1 receptor agonists, but blocked desensitization of D1A receptors. However, simultaneous activation of A1 and D1A receptors promoted a delayed D1A receptor desensitization. This suggests that functional interaction between A1 and D1A receptors may depend on the activation kinetics of components regulating D1 receptor responses, acting differentially on D1A and D1B receptors.     

Population genomics of the raccoon dog (<Emphasis Type="Italic">Nyctereutes procyonoides</Emphasis>) in Denmark: insights into invasion history and population development

The raccoon dog (Nyctereutes procyonoides) has a wide distribution in Europe and is a prominent example of a highly adaptable alien species. It has been recorded sporadically in Denmark since 1980 but observations since 2008 suggested that the species had established a free-ranging, self-sustaining population. To elucidate the origin and genetic patterns of Danish raccoon dogs, we studied the population genomics of 190 individuals collected in Denmark (n = 141) together with reference captive individuals from Poland (n = 21) and feral individuals from different European localities (Germany, Poland, Estonia and Finland, n = 28). We used a novel genotyping-by-sequencing approach simultaneously identifying and genotyping a large panel of single nucleotide polymorphisms (n = 4526). Overall, there was significant indication for contemporary genetic structuring of the analysed raccoon dog populations, into at least four different clusters, in spite of the existence of long distance gene flow and secondary admixture from different population sources. The Danish population was characterized by a high level of genetic admixture with neighbouring feral European ancestries and the presence of private clusters, non-retrieved in any other feral or captive populations sampled. These results suggested that the raccoon dog population in Denmark was founded by escapees from genetically unidentified Danish captive stocks, followed by a recent admixture with individuals migrating from neighbouring Germany.     

Transfer of Antibiotic Resistance in Staphylococcus aureus

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Fanconi DNA repair pathway is required for survival and long-term maintenance of neural progenitors

Although brain development abnormalities and brain cancer predisposition have been reported in some Fanconi patients, the possible role of Fanconi DNA repair pathway during neurogenesis is unclear. We thus addressed the role of fanca and fancg, which are involved in the activation of Fanconi pathway, in neural stem and progenitor cells during brain development and adult neurogenesis. Fanca(-/-) and fancg(-/-) mice presented with microcephalies and a decreased neuronal production in developing cortex and adult brain. Apoptosis of embryonic neural progenitors, but not that of postmitotic neurons, was increased in the neocortex of fanca(-/-) and fancg(-/-) mice and was correlated with chromosomal instability. In adult Fanconi mice, we showed a reduced proliferation of neural progenitor cells related to apoptosis and accentuated neural stem cells exhaustion with ageing. In addition, embryonic and adult Fanconi neural stem cells showed a reduced capacity to self-renew in vitro. Our study demonstrates a critical role for Fanconi pathway in neural stem and progenitor cells during developmental and adult neurogenesis.     

Restoration Strategies to Improve Connectivity for Golden-Headed Lion Tamarins (<Emphasis Type="Italic">Leontopithecus chrysomelas</Emphasis>) in the Bahian Atlantic Forest,Brazil

Habitat loss and fragmentation are the leading causes of biodiversity decline world-wide. Animals sensitive to fragmentation experience reduced dispersal, breeding opportunities, and genetic diversity, making them vulnerable to local extinction. Over the last few decades the Atlantic Forest of Brazil has been extremely fragmented, with only 11–16% of forest remaining. The Brazilian government and nongovernmental organizations have taken actions through legislation and conservation initiatives to restore forest. Using computer modeling, we compared how alternative forest restoration strategies could improve functional connectivity for golden-headed lion tamarins (Leontopithecus chrysomelas) in Southern Bahia, Brazil. Strategies differed by restoration configuration, including Within- and Across-Property approaches, and restoration amount (0–20% restoration). Increasing restoration amounts resulted in greater species functional connectivity, and Within-Property and Across-Property strategies both had significantly more connectivity than the Random strategy. We suggest restoration management consider the size and placement of restored forest, and that riparian forest be restored first to create dispersal corridors and reestablish essential ecosystem services. We further suggest the importance of forming canopy bridges across narrow sections of rivers during the early stages of the restoration process to promote increased connectivity of these newly restored areas. Our findings can aid managers and landowners in understanding the implications of different restoration strategies for highly arboreal, matrix-sensitive species.     

Insight into the role of CYBA A640G and C242T gene variants and coronary heart disease risk. A case-control study

The CYBA gene variants have been inconsistently associated with coronary heart disease (CHD) risk. A case-control study was conducted genotyping 619 subjects to explore the contribution of C242T and A640G to CHD risk in the population. A significant risk was found associated with GG homozygosity (odds ratio (OR) 2.132, 95% confidence interval, 1.113-4.085). The C242T variant was associated with CHD risk in women. Bias due to population stratification was analysed. Phenotype changes linked to these polymorphisms were evaluated. Superoxide measurements revealed higher production as indicated by the presence of the G and T alleles. Differences in mRNA concentration in heterozygous A640G samples were analysed. Higher levels of G allele mRNA compared with A allele mRNA were found. NAD(P)H oxidase p22phox sub-unit expression was evaluated with Western blot. Experiments revealed a gradual relationship in p22phox protein expression according to genotypes of the analysed variants. Those GG TT double homozygous showed increased p22phox protein expressions regarding AA CC double homozygous. This study has demonstrated increased expression and activity of the NAD(P)H system components during atherogenesis and the results could help explain the relevance of the A640G variant as a CHD marker.     

First exploration of Nitrobacter diversity in soils by a PCR cloning-sequencing approach targeting functional gene nxrA

Nitrite oxidoreductase (NXR) is the key enzyme responsible for the oxidation of NO(2)(-) to NO(3)(-) in nitrite-oxidizing bacteria. For the first time a molecular approach for targeting the nxrA gene was developed, encoding the catalytic subunit of the NXR, to study diversity of Nitrobacter-like organisms based on the phylogeny of nxrA gene sequences in soils. NxrA sequences of the Nitrobacter strains analysed (Nitrobacter hamburgensis, Nitrobacter vulgaris, Nitrobacter winogradskyi, Nitrobacter alkalicus) by PCR, cloning and sequencing revealed the occurrence of multiple copies of nxrA genes in these strains. The copy number and similarity varied among strains. The diversity of Nitrobacter-like nxrA sequences was explored in three soils (a French permanent pasture soil, a French fallow soil, and an African savannah soil) using a cloning and sequencing approach. Most nxrA sequences found in these soils (84%) differed from nxrA sequences obtained from Nitrobacter strains. Moreover, the phylogenetic distribution and richness of nxrA-like sequences was extremely variable depending on soil type. This nxrA tool extends the panel of functional genes available for studying bacteria involved in the nitrogen cycle.