Effects of environmental factors on the ecology and survival of a widespread,endemic Cerrado frog

Understanding the mechanisms that affect habitat use by vertebrates is critical for understanding how species are distributed across landscapes and how they cope with habitat change. The Brazilian Savanna (the Cerrado) has vegetation ranging from grassland to woodland savannas and harbors a rich and diverse amphibian fauna impacted by accelerated habitat loss. Here, we test the influence of vegetation type (from grassy scrubland to woodland) and distance from breeding sites (ephemeral water bodies) on body size, abundance, and survival of the frog Physalaemus nattereri in a natural metapopulation system of south-central Brazil. We also test whether body size is a significant predictor of population abundance. We found that the abundance of P. nattereri varies according to the mean snout–vent length of each metapopulation (sampling unit), as well as a higher estimated mortality rate in woodlands compared with typical Cerrado. Furthermore, we found no difference in estimated mortality among sampling units located far or close to ephemeral water bodies. Thus, our results highlight variable responses of P. nattereri metapopulations to environmental factors, despite the observed high heterogeneity among sampled habitats and the importance of ephemeral water bodies for reproduction. These findings highlight that land cover and availability of breeding sites might not always interact to explain population persistence of Cerrado frogs.     

Immunogold localization of phytoene desaturase in higher plant chloroplasts

In situ location of phytoene desaturase, a key enzyme in the carotenoid biosynthesis pathway, has been investigated in chloroplasts from higher plants. For this purpose, an antiserum has been raised against the phytoene desaturase from the cyanobacterium Synechococcus PCC 7942 overexpressed in E. coli . The specifity of this antiserum was demonstrated by inhibition of the enzymatic desaturation reaction in vitro. The antiserum was further purified and immunoabsorbed with E. coli proteins. The resulting IgG-fraction was tested by western blotting against membrane proteins from chloroplasts of tobacco ( Nicotiana tabacum L. cv. Samsun) and spinach ( Spinacia oleracea L. cv. Atlanta). Apparent molecular masses of immunoreactive proteins were 62 and 64 kDa. A western blot of different membrane fractions of spinach chloroplasts (inner and outer envelopes, and thylakoids) indicated a localization of the phytoene desaturase in thylakoids. A post embedding immunogold microscopy procedure was employed. In these experiments the main labelling (79%) was associated with thylakoid membranes of tobacco chloroplasts. Of the counted colloidal gold particles, 16% were found in the stroma. Only 5% were detected in the envelope membranes. These results give clear evidence that at least the majority of phytoene desaturase molecules is localized within thylakoid membranes of higher plant chloroplasts and that the presence of the enzyme in the envelope is of minor significance.     

IL-1β Signaling Promotes CNS-Intrinsic Immune Control of West Nile Virus Infection

West Nile virus (WNV) is an emerging flavivirus capable of infecting the central nervous system (CNS) and mediating neuronal cell death and tissue destruction. The processes that promote inflammation and encephalitis within the CNS are important for control of WNV disease but, how inflammatory signaling pathways operate to control CNS infection is not defined. Here, we identify IL-1β signaling and the NLRP3 inflammasome as key host restriction factors involved in viral control and CNS disease associated with WNV infection. Individuals presenting with acute WNV infection displayed elevated levels of IL-1β in their plasma over the course of infection, suggesting a role for IL-1β in WNV immunity. Indeed, we found that in a mouse model of infection, WNV induced the acute production of IL-1β in vivo, and that animals lacking the IL-1 receptor or components involved in inflammasome signaling complex exhibited increased susceptibility to WNV pathogenesis. This outcome associated with increased accumulation of virus within the CNS but not peripheral tissues and was further associated with altered kinetics and magnitude of inflammation, reduced quality of the effector CD8⁺ T cell response and reduced anti-viral activity within the CNS. Importantly, we found that WNV infection triggers production of IL-1β from cortical neurons. Furthermore, we found that IL-1β signaling synergizes with type I IFN to suppress WNV replication in neurons, thus implicating antiviral activity of IL-1β within neurons and control of virus replication within the CNS. Our studies thus define the NLRP3 inflammasome pathway and IL-1β signaling as key features controlling WNV infection and immunity in the CNS, and reveal a novel role for IL-1β in antiviral action that restricts virus replication in neurons.     

Synergist effects of n-acetylcysteine and deferoxamine treatment on behavioral and oxidative parameters induced by chronic mild stress in rats

A growing body of evidence has pointed to a relationship between oxidative stress and depression. Thus, the present study was aimed at evaluating the effects of the antioxidants n-acetylcysteine (NAC), deferoxamine (DFX) or their combination on sweet food consumption and oxidative stress parameters in rats submitted to 40 days of exposure to chronic mild stress (CMS). Our results showed that in stressed rats treated with saline, there was a decrease in sweet food intake and treatment with NAC or NAC in combination with DFX reversed this effect. Treatment with NAC and DFX decreased the oxidative damage, which include superoxide and TBARS production in submitochondrial particles, and also thiobarbituric acid reactive substances (TBARS) levels and carbonyl proteins in the prefrontal cortex, amygdala and hippocampus. Treatment with NAC and DFX also increased the activity of the antioxidant enzymes, superoxide dismutase and catalase in the same brain areas. Even so, a combined treatment with NAC and DFX produced a stronger increase of antioxidant activities in the prefrontal cortex, amygdala and hippocampus. The results described here indicate that co-administration may induce a more pronounced antidepressant activity than each treatment alone. In conclusion, these results suggests that treatment with NAC or DFX alone or in combination on oxidative stress parameters could have positive effects against neuronal damage caused by oxidative stress in major depressive disorders.     

Changes in alanine and glutamine transport during rat red blood cell maturation

Alanine and glutamine transport have been studied during red blood cell maturation in the rat. Kinetic parameters of Na⁺-dependent L-alanine transport were:K _m 0.43 and 1.88 mM andV _max 158 and 45 nmoles/ml ICW/min for reticulocytes and erythrocytes, respectively. During red cell maturation in the rat there is a loss of capacity and affinity of the system ASC for L-alanine transport. The values for Na⁺-dependent L-glutamine transport in reticulocytes wereK _m 0.51 mM andV _max 157 nmoles/ml ICW/min. On the other hand, a total loss of L-glutamine transport mediated by both N and ASC systems is demonstrated in mature red cells. This seems to indicate that during rat red cell maturation the system N disappears. Furthermore, the system ASC specificity in mature cells changes, and glutamine enters the red cell by non-mediated diffusion processes.     

Evolutionary history of bulldog bats (genus Noctilio): recent diversification and the role of the Caribbean in Neotropical biogeography

We present phylogenetic relationships and phylogeographic patterns of the two species of bulldog bats, genus Noctilio. Using a comprehensive sampling of 118 individuals throughout the species distribution, we investigated the distribution of molecular variation in one nuclear and two mitochondrial markers. Phylogenetic trees do not recover Noctilio albiventris as a monophyletic group and point to three similar‐age intraspecific genetic lineages, suggesting cryptic diversity in this taxon. These lineages correspond to the subspecies previously proposed, and are strongly associated with major river basins in South America. Analyses also suggest a very recent origin for the fishing bat Noctilio leporinus, which probably originates from N. albiventris, with a population expansion corresponding to its invasion in South America. Based on our analysis, the speciation event was dated in the Pleistocene epoch and seems to be associated with the variation of the sea level in the Caribbean islands. The present work indicates how phylogeographic studies support the identification of independent evolutionary lineages, driving new systematic/taxonomic investigations, while at the same time shed light on the role of the Caribbean in shaping Neotropical bat fauna diversity. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.