Using chorotypes to deconstruct biogeographical and biodiversity patterns: the case of breeding waterbirds in Europe

Aim To deconstruct the biodiversity pattern of the 152 waterbird species breeding in Europe to better understand its multiple causal processes. Location Continental Europe, Iceland and the British Isles. Methods We considered the orders that are typically comprised by swimming, diving or wading birds, which inhabit marshes, fens, peatlands and fresh, brackish or salt waters, including coastal waters. We used the 55 main river basins of Europe as geographical units, and searched for either chorotypes (groups of similar species distributions) or gradual replacement of species throughout the river basins. Chorotypes were recognized by applying a probabilistic classification method to the distributions. Then we used GLM to characterize the extent and the species richness of each chorotype according to energy availability (higher levels of environmental energy favouring the presence of species), climatic stress due to an excess of energy, availability of water, productivity, seasonality and surface area. Results One hundred and forty species significantly aggregate into nine chorotypes. The other 12 species, most of them marine, are centred on Great Britain, dropping away progressively on coasts further away from there. Differences in either the availability of energy or climatic stress significantly characterized the distribution of seven chorotypes comprising 90.8% of the species. Main conclusions Chorotypes are meaningful and useful to deconstruct biodiversity patterns. Our results suggest that energy is the main factor related to the biogeographical patterns of breeding waterbirds in Europe, and provide an insight into regional trends of species richness previously analysed with a habitat‐scale perspective.     

Pregnancy success of lactating Holstein cows after a single administration of a sustained-release formulation of recombinant bovine somatotropin

Background

Results regarding the use of bovine somatotropin for enhancing fertility in dairy cattle are variable. Here, the hypothesis was tested that a single injection of a sustained-release preparation of bovine somatotropin (bST) during the preovulatory period would improve pregnancy success of lactating dairy cows at first service.

Results

The first experiment was conducted in a temperate region of Mexico. Cows inseminated following natural estrus or timed artificial insemination were given a single injection of bST or a placebo injection at insemination (n = 100 cows per group). There was no significant difference between bST and control groups in the proportion of inseminated cows diagnosed pregnant (29 vs 31% pregnant). The second experiment was performed during heat stress in Florida. Cows were subjected to an ovulation synchronization regimen for first insemination. Cows treated with bST received a single injection at 3 days before insemination. Controls received no additional treatment. As expected, bST did not increase vaginal temperature. Treatment with bST did not significantly increase the proportion of inseminated cows diagnosed pregnant although it was numerically greater for the bST group (24.2% vs 17.8%, 124–132 cows per group). There was a tendency (p = 0.10) for a smaller percent of control cows to have high plasma progesterone concentrations (≥ 1 ng/ml) at Day 7 after insemination than for bST-treated cows (72.6 vs 81.1%). When only cows that were successfully synchronized were considered, the magnitude of the absolute difference in the percentage of inseminated cows that were diagnosed pregnant between bST and control cows was reduced (24.8 vs 22.4% pregnant for bST and control).

Conclusion

Results failed to indicate a beneficial effect of bST treatment on fertility of lactating dairy cows.

     

Identification of low-dye-binding (ldb) mutants of Saccharomyces cerevisiae

We have completed the identification of Saccharomyces cerevisiae genes that are defective in previously isolated ldb (low-dye-binding) mutants. This was done by complementation of the mutant's phenotype with DNA fragments from a genomic library and by running standard tests of allelism with single-gene deletion mutants of similar phenotype. The results were as follows: LDB2 is allelic to ERD1; LDB4 to SPC72; LDB5 to RLR1; LDB6 to GON7/YJL184W; LDB7 to YBL006C; LDB9 to ELM1; LDB10 to CWH36; LDB11 to COG1; LDB12 to OCH1; LDB13 to VAN1; LDB14 to BUD32; and LDB15 to PHO85. Since the precise function of some of the genes is not known, these data may contribute to the functional characterization of the S. cerevisiae genome.     

Comparison of approaches to combine species distribution models based on different sets of predictors

Distribution models should take into account the different limiting factors that simultaneously influence species ranges. Species distribution models built with different explanatory variables can be combined into more comprehensive ones, but the resulting models should maximize complementarity and avoid redundancy. Our aim was to compare the different methods available for combining species distribution models. We modelled 19 threatened vertebrate species in mainland Spain, producing models according to three individual explanatory factors: spatial constraints, topography and climate, and human influence. We used five approaches for model combination: Bayesian inference, Akaike weight averaging, stepwise variable selection, updating, and fuzzy logic. We compared the performance of these approaches by assessing different aspects of their classification and discrimination capacity. We demonstrated that different approaches to model combination give rise to disparities in the model outputs. Bayesian integration was systematically affected by an error in the equations that are habitually used in distribution modelling. Akaike weights produced models that were driven by the best single factor and therefore failed at combining the models effectively. The updating and the stepwise approaches shared recalibration as the basic concept for model combination, were very similar in their performance, and showed the highest sensitivity and discrimination capacity. The fuzzy‐logic approach yielded models with the highest classification capacity according to Cohen's kappa. In conclusion: 1) Bayesian integration, employing the currently used equation, and the Akaike weight procedure should be avoided; 2) the updating and stepwise approaches can be considered minor variants of the same recalibrating approach; and 3) there is a trade‐off between this recalibrating approach, which has the highest sensitivity, and fuzzy logic, which has the highest overall classification capacity. Recalibration is better if unfavourable conditions in one environmental factor may be counterbalanced with favourable conditions in a different factor, otherwise fuzzy logic is better.     

Downregulation of uPA, uPAR and MMP-9 using small, interfering, hairpin RNA (siRNA) inhibits glioma cell invasion, angiogenesis and tumor growth

The diffuse, extensive infiltration of malignant gliomas into the surrounding normal brain is believed to rely on modification of the proteolysis of extracellular matrix components. Our previous results clearly demonstrate that uPA, uPAR and MMP-9 concentrations increase significantly during tumor progression and that tumor growth can be inhibited with antisense stable clones of these molecules. Because antisense-mediated gene silencing does not completely inhibit the translation of target mRNA and high concentrations of antisense molecules are required to achieve gene silencing, we used the RNAi approach to silence uPA, uPAR and MMP-9 in this study. We examined a cytomegalovirus (CMV) promoter-driven DNA-template approach to induce hairpin RNA (hpRNA)-triggered RNAi to inhibit uPA, uPAR and MMP-9 gene expression with a single construct. uPAR protein levels and enzymatic activity of uPA and MMP-9 were found to significantly decrease in cells transfected with a plasmid expressing hairpin siRNA for uPAR, uPA and MMP-9. pU(2)M-transfected SNB19 cells significantly decreased uPA, uPAR and MMP-9 expression compared to mock and EV/SV-transfected cells, determined by immunohistochemical analysis. Furthermore, the effect of the single constructs for these molecules was a specific inhibition of their respective protein levels, as demonstrated by immunohistochemical analysis. After transfection with a plasmid vector expressing dsRNA for uPA, uPAR and MMP-9, glioma-cell invasion was retarded compared with mock and EV/SV-treated groups, demonstrated by Matrigel-invasion assay and spheroid-invasion assay. Downregulation of uPA, uPAR and MMP-9 using RNAi inhibited angiogenesis in an in vitro (co-culture) model. Direct intratumoral injections of plasmid DNA expressing hpRNA for uPA, uPAR and MMP-9 significantly regressed pre-established intracranial tumors in nude mice. In addition, cells treated with RNAi for uPAR, uPA and MMP-9 showed reduced pERK levels compared with parental and EV/SV-treated SNB19 cells. Our results support the therapeutic potential of RNAi as a method for gene therapy in treating gliomas.     

The mnn2 mutant of Saccharomyces cerevisiae is affected in phosphorylation of N-linked oligosaccharides

We studied the phosphorylation of the inner core region of N-linked oligosaccharides in the mannan defective mutant Saccharomyces cerevisiae mnn2 which was described as unable to synthesize branches on the outer chain. We performed structural studies of the N-oligosaccharides synthesized by the strains mnn2, mnn1mnn2mnn9 and mnn1mnn9ldb8, and the results are compared with previously published structural data of mnn1mnn2mnn10 and mnn1mnn9 [Hernández, L.M., Ballou, L., Alvarado, E., Tsai, P.-K. and Ballou, C.E. (1989) J. Biol. Chem. 264, 13648-13659]. We conclude that the mnn2/ldb8 mutation is responsible for the inhibition of incorporation of phosphate to mannose A(3) (see below), a particular phosphorylation site of the inner core, while phosphorylation at the other possible site (mannose C(1)) is allowed, although it is also reduced. *Phosphorylation sites in mnn1mnn9. (see structure below)     

Calcium Modulates Osmosensitive Taurine Efflux in HeLa Cells

The role of Ca²⁺ in the signaling transduction pathway involved in osmosensitive taurine efflux in HeLa cells was studied using radiotracer efflux techniques. Taurine efflux induced by extracellular hypotonicity was decreased by 85% by removal of extracellular Ca²⁺ and simultaneous depletion of intracellular Ca²⁺ stores with thapsigargin. Extracellular Ca²⁺ removal, thapsigargin treatment, or addition of Gd³⁺ all decreased taurine efflux by ～50%. To explore the putative signal transduction pathways involved in swelling-induced taurine efflux, HeLa cells were exposed to PP1, an inhibitor of the Src family of tyrosine kinases, the phospholipase C inhibitor U73122, the IP₃ receptor antagonist 2-APB, and the generic protein kinase C inhibitor chelerythrine. All of these treatments caused ～50% inhibition of taurine release in Ca²⁺-rich extracellular medium and ～85%–90% in Ca²⁺-free conditions. The inhibitors of the conventional protein kinase C isoforms BIM-1 and Gö6976 reduced taurine efflux to a lesser extent. Acute (10-min) exposure to the phorbol ester tetradecanoyl phorbol acetate (TPA) increased taurine efflux in 25%, whilst overnight exposure had an inhibitory effect decreasing efflux by 22%. A working model for activation of osmosensitive taurine efflux in HeLa cells involving different Ca²⁺ signaling pathways is presented.     

First-dose analgesic effect of the cyclo-oxygenase-2 selective inhibitor lumiracoxib in osteoarthritis of the knee: a randomized, double-blind, placebo-controlled comparison with celecoxib [NCT00267215]

Cyclo-oxygenase-2 selective inhibitors are frequently used to manage osteoarthritis. We compared the analgesic efficacy of the novel cyclo-oxygenase-2 selective inhibitor lumiracoxib (Prexige) versus placebo and celecoxib in patients with knee osteoarthritis. This seven day, double-blind, placebo and active comparator controlled, parallel group study included 364 patients aged > or = 50 years with moderate-to-severe symptomatic knee osteoarthritis. Patients received lumiracoxib 400 mg/day (four times the recommended chronic dose in osteoarthritis; n = 144), placebo (n = 75), or celecoxib 200 mg twice daily (n = 145). The primary variable was actual pain intensity difference (100 mm visual-analogue scale) between baseline and the mean of three hour and five hour assessments after the first dose. Actual pain intensity difference, average and worst pain, pain relief and functional status (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]) were measured over seven days. Patients also completed a global evaluation of treatment effect at study end or premature discontinuation. For the primary variable, the superiority of lumiracoxib versus placebo, the noninferiority of lumiracoxib versus celecoxib, and the superiority of lumiracoxib versus celecoxib were assessed by closed test procedure adjusting for multiplicity, thereby maintaining the overall 5% significance level. In addition, celecoxib was assessed versus placebo in a predefined exploratory manner to assess trial sensitivity. Lumiracoxib provided better analgesia than placebo 3-5 hours after the first dose (P = 0.004) through to study end. The estimated difference between lumiracoxib and celecoxib 3-5 hours after the first dose was not significant (P = 0.185). Celecoxib was not significantly different from placebo in this analysis (P = 0.069). At study end 13.9% of lumiracoxib-treated patients reported complete pain relief versus 5.5% and 5.3% of celecoxib and placebo recipients, respectively. WOMAC total and subscales improved for both active treatments versus placebo except for difficulty in performing daily activities, for which celecoxib just failed to achieve significance (P = 0.056). In the patient's global evaluation of treatment effect, 58.1% of patients receiving lumiracoxib rated treatment as 'excellent' or 'good', versus 48.6% of celecoxib and 25.3% of placebo patients. Lumiracoxib was well tolerated. The overall incidence of adverse events was similar across treatment groups.     

Activation of H2O2-induced VSOR Cl- currents in HTC cells require phospholipase Cgamma1 phosphorylation and Ca2+ mobilisation.

Volume-sensitive outwardly rectifying (VSOR) Cl(-) channels participate in several physiological processes such as regulatory volume decrease, cell cycle regulation, proliferation and apoptosis. Recent evidence points to a significant role of hydrogen peroxide (H(2)O(2)) in VSOR Cl(-) channel activation. The aim of this study was to determine the signalling pathways responsible for H(2)O(2)-induced VSOR Cl(-) channel activation. In rat hepatoma (HTC) cells, H(2)O(2) elicited a transient increase in tyrosine phosphorylation of phospholipase Cgamma1 (PLCgamma1) that was blocked by PP2, a Src-family protein kinases inhibitor. Also, H(2)O(2) triggered an increase in cytosolic [Ca(2+)] that paralleled the time course of PLCgamma1 phosphorylation. The H(2)O(2)-induced [Ca(2+)](i) rise was prevented by the generic phospholipase C (PLC) inhibitor U73122 and the inositol 1,4,5-trisphosphate-receptor (IP(3)R) blocker 2-APB. In line with these results, manoeuvres that prevented PLCgamma1 activation and/or [Ca(2+)](i) rise, abolished H(2)O(2)-induced VSOR Cl(-) currents. Furthermore, in cells that overexpress a phosphorylation-defective dominant mutant of PLCgamma1, H(2)O(2) did not induce activation of VSOR Cl(-) currents. All these H(2)O(2)-induced effects were independent of extracellular Ca(2+). Our findings suggest that activation of PLCgamma1 and subsequent Ca(2+)(i) mobilisation mediate H(2)O(2)-induced VSOR Cl(-) currents, indicating that H(2)O(2) operates via redox-sensitive signalling pathways akin to those activated by osmotic challenges.