Regulation of L-Type Calcium Channels in GH4 Cells via A1 Adenosine Receptors

Abstract: Identification of A₁ adenosine receptors (A₁Rs) in a tumor cell line derived from rat pituitary (GH₄ cells) was performed by ligand binding and immunological experiments. Subsequently, the involvement of A₁Rs in the regulation of calcium conductance was studied in these cells. The agonist N ⁶-( R )-(2-phenylisopropyl)adenosine ( R -PIA) did not modify the intracellular calcium basal levels, whereas it inhibited the increase produced by 15 m M KCl depolarization. The antagonist 1,3-dipropyl-8-cyclopentylxanthine led to the opening of voltage-dependent cell surface calcium channels in the absence of exogenous KCl. The channels were of the L type because the effect was abolished by calciseptine and by verapamil. These results suggest that endogenous adenosine exerts a tonic inhibitory effect on calcium transport. This was confirmed by the high adenosine concentration found in cell supernatants (up to 1 µ M ) and by the calcium mobilization produced by exogenously added adenosine deaminase. In depolarizing conditions, the calcium peak in the presence of adenosine deaminase was reduced when cells were preincubated with R -PIA, thus suggesting that A₁R activation regulates the intensity of depolarization. These results demonstrate that adenosine is an important regulator of the physiological state of pituitary tumor cells by modulating, in an autocrine manner, the activity of L-type voltage-dependent calcium channels.     

The B-chromosome system of the grasshopper Eyprepocnemis plorans subsp. plorans (Charpentier)

Supernumerary chromosomes of two types have been observed in the grasshopper Eyprepocnemis plorans subsp. plorans. One of these (the B-type) is similar in size to an S autosome; the other is smaller (B-type). Both are telocentric and mitotically stable. The frequencies of individuals with the B-type supernumeraries in five natural populations were 56, 56, 70, 71 and 30 per cent respectively. The equivalent levels of the B-type supernumerary were 0, 0, 13, 3 and 0 per cent respectively. Because of the relative infrequency of the B-type only the B-type has been studied in detail. In males with 1B, anaphase I segregation of X and B was random in four populations but non-random in that from Otivar. Here the B was distinctive in having a secondary constriction near the centromere. A study of chiasma frequency among A-chromosomes revealed that the B-type supernumerary increases significantly both the mean chiasma frequency and the between-cell variance. A comparison of body morphometrics failed to reveal any effect of these B-chromosomes on the exophenotype.     

Reproductive costs in terrestrial male vertebrates: insights from bird studies

Reproduction requires resources that cannot be allocated to other functions resulting in direct reproductive costs (i.e. trade-offs between current reproduction and subsequent survival/reproduction). In wild vertebrates, direct reproductive costs have been widely described in females, but their occurrence in males remains to be explored. To fill this gap, we gathered 53 studies on 48 species testing direct reproductive costs in male vertebrates. We found a trade-off between current reproduction and subsequent performances in 29% of the species and in every clade. As 73% of the studied species are birds, we focused on that clade to investigate whether such trade-offs are associated with (i) levels of paternal care, (ii) polygyny or (iii) pace of life. More precisely for this third question, it is expected that fast species (i.e. short lifespan, early maturity, high fecundity) pay a cost in terms of survival, whereas slow species (with opposite characteristics) do so in terms of fecundity. Our findings tend to support this hypothesis. Finally, we pointed out the potential confounding effects that should be accounted for when investigating reproductive costs in males and strongly encourage the investigation of such costs in more clades to understand to what extent our results are relevant for other vertebrates.     

Uncoordinated reintroductions of Eurasian lynx might be a threat for the species recovery in Central Europe

Biodiversity and Conservation -     

Ancient saltern metagenomics: tracking changes in microbes and their viruses from the underground to the surface

Microbial communities in hypersaline underground waters derive from ancient organisms trapped within the evaporitic salt crystals and are part of the poorly known subterranean biosphere. Here, we characterized the viral and prokaryotic assemblages present in the hypersaline springs that dissolve Triassic-Keuper evaporite rocks and feed the Añana Salt Valley (Araba/Alava, Basque Country, Spain). Four underground water samples (around 23% total salinity) with different levels of exposure to the open air were analysed by means of microscopy and metagenomics. Cells and viruses in the spring water had lower concentrations than what are normally found in hypersaline environments and seemed to be mostly inactive. Upon exposure to the open air, there was an increase in activity of both cells and viruses as well as a selection of phylotypes. The underground water was inhabited by a rich community harbouring a diverse set of genes coding for retinal binding proteins. A total of 35 viral contigs from 15 to 104 kb, representing partial or total viral genomes, were assembled and their evolutionary changes through the spring system were followed by SNP analysis and metagenomic island tracking. Overall, both the viral and the prokaryotic assemblages changed quickly upon exposure to the open air conditions.     

Responses of ‘Conference’ Pear to Deficit Irrigation: Water Relations, Leaf Discrimination Against 13CO2, Tree Starch Content, Growth, and Recovery After Rewatering

Responses to deficit irrigation (DI) throughout the fruit-growing season were studied in ‘Conference’ pear grafted onto quince M-A rootstock and grown in large containers. The treatments were (1) full irrigation (FI), (2) DI during Stage I of fruit growth (DI-Stage I), and (3) DI during Stage II of fruit growth (DI-Stage II). Four whole trees were sampled before Stage I and from all treatments at the end of Stage I, end of Stage II (fruit harvest), and before leaf fall. There was less discrimination against ¹³CO₂ in DI leaves, indicative of reduced photosynthetic capacity. DI treated trees had lower starch content in branches and trunks but root starch concentration was the same between DI- and FI-treated trees. Compared to FI-treated trees, leaf, shoot, branch, and trunk dry biomass was reduced by 34, 50, 37, and 32 %, respectively, in DI-Stage I and by 45, 73, 37, and 22 % in DI-Stage II. Root growth was not affected by DI. Trees had limited capacity for storing starch in roots. Recovery of the aboveground starch concentration for DI treatments occurred within 1 month after rewatering but total starch content never recovered.     

Molecular characterization of PVAS3: An asparagine synthetase gene from common bean prevailing in developing organs

In common bean, asparagine synthetase (AS; EC 6.3.5.4) is encoded by three members of a multigene family called PVAS1, PVAS2 and PVAS3. Two of these genes, PVAS1 and PVAS2, have been extensively studied, but little is known about PVAS3, remaining unclear whether PVAS3 function is redundant to the other AS or if it plays a specific role in Phaseolus vulgaris metabolism. In this work, we used a molecular approach to characterize PVAS3 expression and to gain some knowledge about its physiological function. We showed that, in contrast to PVAS1 and PVAS2, PVAS3 was expressed in all organs analyzed. Interestingly, PVAS3 was the AS gene most highly expressed in nodules, leaves and pods at the earliest stages of development, and its expression decreased as these organs developed. Expression of PVAS3 parallels the accumulation of AS protein and the asparagine content during the earliest stages of nodule, leaf and pod development, suggesting an important role for PVAS3 in the synthesis of asparagine in that period. Furthermore, PVAS3 was not repressed by light, as most class-II AS genes. Surprisingly, fertilization of nodulated plants with nitrate or ammonium, conditions that induce PVAS1 and PVAS2 and the shift from ureides to amide synthesis, repressed the expression of PVAS3 in nodules and roots. The possible implications of this regulation are discussed.     

Pollen analysis of honeys from the Mamora forest region (NW Morocco)

The present work refers to the pollen analysis of 35 Moroccan honey samples from the Mamora forest region. The samples were directly provided by the beekeepers, all professionals. The quantitative analysis showed that nectar is the main honey source in the samples studied, and that most honeys have a medium-low presence of botanical elements (BEN). The qualitative analysis of the samples showed the presence of 54 taxa belonging to 29 families, and 31 of the samples were unifloral: 24 of eucalyptus, 3 of orange, 2 of Loeflingia, 1 of mint and 1 of Ridolfia segetum. The eucalyptus honeys of the studied region are characterized by their high content in pollen grains (NGP; x¯=180000) and their low honeydew indicator elements content (HDE; x¯=4000); Plantago f. (present in 70% of the samples), Quercus f. and Brassicaceae (50%) and Ceratonia siliqua (30%) could be mentioned among the characteristic accompanying species of this honey type.     

Cocaine Inhibits Dopamine D2 Receptor Signaling via Sigma-1-D2 Receptor Heteromers

Under normal conditions the brain maintains a delicate balance between inputs of reward seeking controlled by neurons containing the D₁-like family of dopamine receptors and inputs of aversion coming from neurons containing the D₂-like family of dopamine receptors. Cocaine is able to subvert these balanced inputs by altering the cell signaling of these two pathways such that D₁ reward seeking pathway dominates. Here, we provide an explanation at the cellular and biochemical level how cocaine may achieve this. Exploring the effect of cocaine on dopamine D₂ receptors function, we present evidence of σ₁ receptor molecular and functional interaction with dopamine D₂ receptors. Using biophysical, biochemical, and cell biology approaches, we discovered that D₂ receptors (the long isoform of the D₂ receptor) can complex with σ₁ receptors, a result that is specific to D₂ receptors, as D₃ and D₄ receptors did not form heteromers. We demonstrate that the σ₁-D₂ receptor heteromers consist of higher order oligomers, are found in mouse striatum and that cocaine, by binding to σ₁ -D₂ receptor heteromers, inhibits downstream signaling in both cultured cells and in mouse striatum. In contrast, in striatum from σ₁ knockout animals these complexes are not found and this inhibition is not seen. Taken together, these data illuminate the mechanism by which the initial exposure to cocaine can inhibit signaling via D₂ receptor containing neurons, destabilizing the delicate signaling balance influencing drug seeking that emanates from the D₁ and D₂ receptor containing neurons in the brain.     

Enterobacteriaceae Isolated from the River Danube: Antibiotic Resistances,with a Focus on the Presence of ESBL and Carbapenemases

In a clinical setting it seems to be normal these days that a relevant proportion or even the majority of different bacterial species has already one or more acquired antibiotic resistances. Unfortunately, the overuse of antibiotics for livestock breeding and medicine has also altered the wild-type resistance profiles of many bacterial species in different environmental settings. As a matter of fact, getting in contact with resistant bacteria is no longer restricted to hospitals. Beside food and food production, the aquatic environment might also play an important role as reservoir and carrier. The aim of this study was the assessment of the resistance patterns of Escherichia coli and Klebsiella spp. out of surface water without prior enrichment and under non-selective culture conditions (for antibiotic resistance). In addition, the presence of clinically important extended spectrum beta lactamase (ESBL) and carbapenmase harboring Enterobacteriaceae should be investigated. During Joint Danube Survey 3 (2013), water samples were taken over the total course of the River Danube. Resistance testing was performed for 21 different antibiotics. Samples were additionally screened for ESBL or carbapenmase harboring Enterobacteriaceae. 39% of all isolated Escherichia coli and 15% of all Klebsiella spp. from the river Danube had at least one acquired resistance. Resistance was found against all tested antibiotics except tigecycline. Taking a look on the whole stretch of the River Danube the proportion of multiresistances did not differ significantly. In total, 35 ESBL harboring Enterobacteriaceae, 17 Escherichia coli, 13 Klebsiella pneumoniae and five Enterobacter spp. were isolated. One Klebsiella pneumoniae harboring NMD-1 carbapenmases and two Enterobacteriaceae with KPC-2 could be identified. Human generated antibiotic resistance is very common in E. coli and Klebsiella spp. in the River Danube. Even isolates with resistance patterns normally associated with intensive care units are present.