Preliminary results on snow surveys of Pyrenean grey partridge (<Emphasis Type="Italic">Perdix perdix hispaniensis</Emphasis>) in the Cantabrian Mountains

Peripheral populations tend to be smaller and more prone to extinction than those in core areas. Grey partridge Perdix perdix in its southern-most edge occupies mountain habitats, which is unlike any habitat in its northern European range. This makes these mountain ecotypes especially susceptible to range contractions and population decrease is likely the result of the current global change process. In Iberia, the so-called Pyrenean grey partridge subspecies P. p. hispaniensis is considered to be declining but little is known about its real trends and numbers. We locally studied the abundance of the Pyrenean grey partridges in winter by direct observations in the Cantabrian Mountains (NW Spain), while driving on a paved road. In addition, we related observed partridge abundances to different context variables to find the ones better helping to detect this species. The paved road-based censuses were successful, and we detected the presence and abundance of the Pyrenean grey partridge. Individuals and groups were more easily detected from December to February while couples were observed at the end of the winter (i.e. February–March). Wherever open paved roads exist, we strongly recommend using direct observations from them during winter as an adequate tool for Pyrenean grey partridge monitoring. This easy and cost-effective method affordable to managers and conservationists can contribute to a better understanding of the European mountain’s changing ecosystems and help us understanding the population trends of this vulnerable subspecies.     

Leaf-cutting ant nests in temperate environments: mounds,mound damages and nest mortality rate in Acromyrmex lobicornis

The mounds of ant nests have been characterized as structures that facilitate the colonization of habitats subject to extreme temperatures. My objective was to investigate the importance of the mound of Acromyrmex lobicornis (Formicidae, Attini) in this process. In the most climatically rigorous environment that this ant genus lives (northwestern Patagonia), I determined (1) the temperature range within Acromyrmex lobicornis nest-mounds, (2) the influence of mound damages on the mortality or abandonment rate of Acromyrmex lobicornis nests, and (3) compared, from the existing literature, the distribution limits between the species of Acromyrmex that do and do not construct mounds. The mounds of A. lobicornis function as 'thermal buffers' by diminishing the effects of external thermal variations, and previous mound damage increased mortality or abandonment only of colonies with nest mounds constructed on bare ground. Mounds constructed on tussock plants increased their diameter faster and recovered better from perturbations. This may be due to the structural support of plant stems facilitating repair. At a larger scale, the species of Acromyrmex with mounds have more southerly range limits than species that do not construct mounds, indicating an important function of this nest structure for the colonization of temperate environments.     

Temperate Snake Community in South America: Is Diet Determined by Phylogeny or Ecology?

Communities are complex and dynamic systems that change with time. The first attempts to explain how they were structured involve contemporary phenomena like ecological interactions between species (e.g., competition and predation) and led to the competition-predation hypothesis. Recently, the deep history hypothesis has emerged, which suggests that profound differences in the evolutionary history of organisms resulted in a number of ecological features that remain largely on species that are part of existing communities. Nevertheless, both phylogenetic structure and ecological interactions can act together to determine the structure of a community. Because diet is one of the main niche axes, in this study we evaluated, for the first time, the impact of ecological and phylogenetic factors on the diet of Neotropical snakes from the subtropical-temperate region of South America. Additionally, we studied their relationship with morphological and environmental aspects to understand the natural history and ecology of this community. A canonical phylogenetical ordination analysis showed that phylogeny explained most of the variation in diet, whereas ecological characters explained very little of this variation. Furthermore, some snakes that shared the habitat showed some degree of diet convergence, in accordance with the competition-predation hypothesis, although phylogeny remained the major determinant in structuring this community. The clade with the greatest variability was the subfamily Dipsadinae, whose members had a very different type of diet, based on soft-bodied invertebrates. Our results are consistent with the deep history hypothesis, and we suggest that the community under study has a deep phylogenetic effect that explains most of the variation in the diet.     

NLRP3 inflammasome suppression improves longevity and prevents cardiac aging in male mice

While NLRP3‐inflammasome has been implicated in cardiovascular diseases, its role in physiological cardiac aging is largely unknown. During aging, many alterations occur in the organism, which are associated with progressive impairment of metabolic pathways related to insulin resistance, autophagy dysfunction, and inflammation. Here, we investigated the molecular mechanisms through which NLRP3 inhibition may attenuate cardiac aging. Ablation of NLRP3‐inflammasome protected mice from age‐related increased insulin sensitivity, reduced IGF‐1 and leptin/adiponectin ratio levels, and reduced cardiac damage with protection of the prolongation of the age‐dependent PR interval, which is associated with atrial fibrillation by cardiovascular aging and reduced telomere shortening. Furthermore, old NLRP3 KO mice showed an inhibition of the PI3K/AKT/mTOR pathway and autophagy improvement, compared with old wild mice and preserved Nampt‐mediated NAD⁺ levels with increased SIRT1 protein expression. These findings suggest that suppression of NLRP3 prevented many age‐associated changes in the heart, preserved cardiac function of aged mice and increased lifespan.     

Activation of Na+/H+ and K+/H+ exchange by calyculin A in Amphiuma tridactylum red blood cells: implications for the control of volume-induced ion flux activity

Alteration in cell volume of vertebrates results in activation of volume-sensitive ion flux pathways. Fine control of the activity of these pathways enables cells to regulate volume following osmotic perturbation. Protein phosphorylation and dephosphorylation have been reported to play a crucial role in the control of volume-sensitive ion flux pathways. Exposing Amphiuma tridactylu red blood cells (RBCs) to phorbol esters in isotonic medium results in a simultaneous, dose-dependent activation of both Na(+)/H(+) and K(+)/H(+) exchangers. We tested the hypothesis that in Amphiuma RBCs, both shrinkage-induced Na(+)/H(+) exchange and swelling-induced K(+)/H(+) exchange are activated by phosphorylation-dependent reactions. To this end, we assessed the effect of calyculin A, a phosphatase inhibitor, on the activity of the aforementioned exchangers. We found that exposure of Amphiuma RBCs to calyculin-A in isotonic media results in simultaneous, 1-2 orders of magnitude increase in the activity of both K(+)/H(+) and Na(+)/H(+) exchangers. We also demonstrate that, in isotonic media, calyculin A-dependent increases in net Na(+) uptake and K(+) loss are a direct result of phosphatase inhibition and are not dependent on changes in cell volume. Whereas calyculin A exposure in the absence of volume changes results in stimulation of both the Na(+)/H(+) and K(+)/H(+) exchangers, superimposing cell swelling or shrinkage and calyculin A treatment results in selective activation of K(+)/H(+) or Na(+)/H(+) exchange, respectively. We conclude that kinase-dependent reactions are responsible for Na(+)/H(+) and K(+)/H(+) exchange activity, whereas undefined volume-dependent reactions confer specificity and coordinated control.     

Technical evaluation of nested PCR for the diagnosis of experimental sporotrichosis

BackgroundSporotrichosis caused by the dimorphic fungus Sporothrix schenckii can presents in a variety of clinical forms. Routine diagnosis is made by mycology and serology studies. Few investigations have been focused on the evaluation of the molecular diagnosis.AimTo determine the value of the nested PCR technique for the diagnosis of experimental sporotrichosis in organs of mice, and to compare the results with the established laboratory diagnostic procedures.MethodsBALB/c mice were inoculated with growing concentrations of the 2 morphological phases of the fungus. The infected animals were sacrificed one month later and specimens from liver, spleen, lung and testicle were obtained to perform wet mount, culture and molecular diagnosis by the nested PCR technique. Blood samples were obtained for determination of specific antibodies against S. schenckii by the double immunodiffusion procedure.ResultsThe pathogenicity observed with the different concentrations of the fungus inoculated and its isolation by culture, showed scarce differences in the study of specimens from organs infected with the 2 morphological phases of S. schenckii. Specimens from organs of mice inoculated with the mycelial phase when studied by wet mount and culture, showed a higher positivity (100 and 37.5%) than those from mice inoculated with the yeast phase (73 and 2%). However, diagnosis by the nested PCR molecular technique applied to the latter specimens showed a higher percentage of positivity (75%) and 43% of positive results coming from animals infected with the mycelial phase. Specific antibody detection was positive in 100% all groups of infected mice.ConclusionsIn the study of experimental sporotrichosis in mice, the culture, as well as the antibody detection, was an effective diagnostic procedure, while the nested PCR and microscopic studies had a lower diagnostic value.     

Centrin: its secondary structure in the presence and absence of cations

Centrin is a low molecular mass (20 kDa) protein that belongs to the EF-hand superfamily of calcium-binding proteins. Local and overall changes were investigated for interactions between cations and Chlamydomonas centrin using Fourier transform infrared (FT-IR) and circular dichroic (CD) spectroscopies. FT-IR spectral features studied included the amide I' band and the side-chain absorbances for aspartate residues located almost exclusively at the calcium-binding sites in the spectral region of 1700-1500 cm(-1). The amide I' band is exquisitely sensitive to changes in protein secondary structure and is observed to shift from 1626.5 to 1642.7 cm(-1) in the presence and absence of calcium. These spectral bands are complex and were further studied using two-dimensional Fourier transform infrared (2D-FT-IR) correlation along with curve-fitting routines. Using these methods the secondary structure contributions were determined for holocentrin and apocentrin. The alpha-helical content in centrin was determined to be 60%-53% in the presence and absence of cations, respectively. Furthermore, the beta-strand content was determined to be 12%-36%, while the random coil component remained almost constant at 7%-13.5% in the presence and absence of cations, respectively. Changes in the side-chain band are mostly due to the monodentate coordination of aspartate to the cation. A shift of approximately 4 cm(-1) (for the COO- antisymmetric stretch in Asp) from 1565 to 1569 cm(-1) is observed for apocentrin and holocentrin, respectively. Thermal dependence revealed reversible conformational transition temperatures for apocentrin at 37 degrees C and holocentrin at 45 degrees C, suggesting greater stability for holocentrin.     

Deciphering structure-activity relationships in a series of Tat/TAR inhibitors

A series of pentameric “Polyamide Amino Acids” (PAAs) compounds derived from the same trimeric precursor have been synthesized and investigated as HIV TAR RNA ligands, in the absence and in the presence of a Tat fragment. All PAAs bind TAR with similar sub-micromolar affinities but their ability to compete efficiently with the Tat fragment strongly differs, IC₅₀ ranging from 35 nM to >2 μM. While NMR and CD studies reveal that all PAA interact with TAR at the same site and induce globally the same RNA conformational change upon binding, a comparative thermodynamic study of PAA/TAR equilibria highlights distinct TAR binding modes for Tat competitor and non-competitor PAAs. This led us to suggest two distinct interaction modes that have been further validated by molecular modeling studies. While the binding of Tat competitor PAAs induces a contraction at the TAR bulge region, the binding of non-competitor ones widens it. This could account for the distinct PAA ability to compete with Tat fragment. Our work illustrates how comparative thermodynamic studies of a series of RNA ligands of same chemical family are of value for understanding their binding modes and for rationalizing structure-activity relationships.