Nurse abundance determines plant facilitation networks of subtropical forest–grassland ecotone

The theory of complex networks has been recently used to explain ecological associations between nurses and seedlings in plant facilitation systems. The structure of these networks is potentially affected by morphological, ecological and evolutionary factors that can determine the facilitative interactions. In the present study, we evaluate the role of the projected crown area of the nurse plant, the dispersal syndrome, the abundance and the phylogeny relationships with seedlings as drivers of network structure in facilitation networks. To test these parameters, we used an ecotonal forest–grassland system in southern Brazil that experienced historical forest expansion over the grassland in the last few centuries. In two State Parks, Guartelá (GUA) and Vila Velha (VVL), we sampled tree species (nurses and seedlings) along four transects parallel to the forest edge, with five sampling stations along each transect. Tree seedlings (height >0.3 m) were sampled below the nurse's crown (i.e. isolated woody plants, height >1.5 m) and over the grassland area. A total of 160 nurses and 358 seedlings were sampled. Seedling abundance and richness were greater below a nurse's crown than on open grassland. Nurse abundance was the best predictor of the observed interaction matrix. Probabilistic matrices based on abundance, abundance and phylogeny, and dominance were able to predict the observed nestedness values, and they were also closest to the observed connectance, although all of the probabilistic matrices have underestimated this property. Specialization was predicted by abundance and phylogeny, abundance and projected crown area drivers for VVL, and the abundance based models were closest to the predicted specialization for GUA. The result of a similar pattern in predictability between sites indicates that the influences of morphology and evolutionary and ecological processes over the facilitation interactions are equivalent on a regional scale. Woody plant abundance was a key factor for the facilitation networks, driving forest expansion along the subtropical forest–grassland ecotone.     

Resistance training restores metabolic alterations induced by monosodium glutamate in a sex-dependent manner in male and female rats

Despite resistance exercises being associated with health outcomes, numerous issues are still unresolved and further research is required before the exercise can faithfully be prescribed as medicine. The goal of this study was to investigate whether there are sex differences in resistance training effects on metabolic alterations induced by monosodium glutamate (MSG), a model of obesity, in male and female rats. Male and female Wistar rats received MSG (4 g/kg body weight/day, s.c.) from postnatal day 1 to 10. After 10 days from MSG administration, the rats were separated into two groups: MSG-sedentary and MSG-exercised. At postnatal day 60, the animals started a resistance training protocol in an 80 degrees inclined vertical ladder apparatus and performed it for 7 weeks. Control rats received saline solution and were divided in saline-sedentary and saline-exercised. Resistance training restored all plasma biochemical parameters (glucose, cholesterol, triglycerides, aspartate aminotransferase, and alanine aminotransferase) increased in male and female rats treated with MSG. The MSG administration induced hyperglycemia associated with a decrease in the skeletal muscle glucose transporter 4 (GLUT4) levels and accompanied by deregulation in proteins, G-6Pase, and tyrosine aminotransferase, involved in hepatic glucose metabolism of male and female rats. MSG induced dyslipidemia and lipotoxicity in the liver and skeletal muscle of male rats. Regarding female rats, lipotoxicity was found only in the skeletal muscle. The resistance training had beneficial effects against metabolic alterations induced by MSG in male and female rats, through regulation of proteins (GLUT2, protein kinase B, and GLUT4) involved in glucose and lipid pathways in the liver and skeletal muscle.     

Complete genome sequence and in silico analysis of L. interrogans Canicola strain DU114: A virulent Brazilian isolate phylogenetically related to serovar Linhai

Canine leptospirosis is often caused by Leptospira interrogans serovar Canicola. Infected dogs may become asymptomatic carriers of the pathogen, which leads to many public health concerns. In this work, we present the complete genome sequencing and in silico analysis from a virulent Brazilian strain of L. interrogans serovar Canicola, previously isolated from a stray dog in Sao Paulo City. Comparative genomic analysis with a reference genome allowed identification of 1031 INDELs and several arrangement variations. Out of 35,361 SNPs identified, 6780 were missense mutations and 16,114 were synonymous mutations. The Gene Ontology terms more affected by mutations were described. Interestingly, phylogenetic analyses indicated a genetic relatedness of the isolate with serovar Linhai strain 56,609. In addition, we found several virulence-related genes and main outer membrane proteins associated with pathogenesis. This genomic information about canine isolates may help to elucidate the molecular diversity and mechanisms of Leptospira spp. pathogenicity.     

Anti-inflammatory and anti-necrotic effects of lectins from Canavalia ensiformis and Canavalia brasiliensis in experimental acute pancreatitis

Glycoconjugate Journal - Lectins isolated from Canavalia ensiformis (ConA) and Canavalia brasiliensis (ConBr) are promising molecules to prevent cell death. Acute pancreatitis, characterized by...     

Savanna–Forest Coexistence Across a Fire Gradient

Ecosystems - Tropical forests and savannas can co-occur in a range of macro-environmental conditions. In these conditions, disturbances and resource availability are thought to control savanna and...     

Increased levels of cortisol are associated with the severity of experimental visceral leishmaniasis in a Leishmania (L.) infantum-hamster model

BackgroundSeveral infectious diseases are associated with hypothalamic-pituitary-adrenal (HPA) axis disorders by elevating circulating glucocorticoids (GCs), which are known to have an immunosuppressive potential. We conducted this study in golden hamsters, a suitable model for human visceral leishmaniasis (VL), to investigate the relationship of Leishmania (L.) infantum infection on cortisol production and VL severity.MethodsL. infantum-infected (n = 42) and uninfected hamsters (n = 30) were followed-up at 30, 120, and 180 days post-infection (dpi). Plasma cortisol was analyzed by radioimmunoassay and cytokines, inducible nitric oxide synthase (iNOS), and arginase by RT-qPCR.ResultsAll hamsters showed splenomegaly at 180 dpi. Increased parasite burden was associated with higher arginase expression and lower iNOS induction. Cortisol levels were elevated in infected animals in all-time points evaluated. Except for monocytes, all other leucocytes showed a strong negative correlation with cortisol, while transaminases were positively correlated. Immunological markers as interleukin (IL)-6, IL-1β, IL-10, and transforming growth-factor-β (TGF-β) were positively correlated to cortisol production, while interferon-γ (IFN-γ) presented a negative correlation. A network analysis showed cortisol as an important knot linking clinical status and immunological parameters.ConclusionsThese results suggest that L. infantum increases the systemic levels of cortisol, which showed to be associated with hematological, biochemical, and immunological parameters associated to VL severity.     

Halothane induces vesicular and carrier-mediated release of [3H]serotonin from rat brain cortical slices

The serotonergic system may play a role during general anesthesia but the effect of the volatile anesthetic halothane on the release of serotonin (5-HT) is not fully understood. Rat brain cortical slices were labeled with [3H]5-HT to investigate the effects of halothane on the release of this neurotransmitter from the central nervous system. Halothane induced an increase on the release of [3H]5-HT that was dependent on incubation time and anesthetic concentration (0.006, 0.012, 0.024, 0.036, 0.048 and 0.072 mM). This effect was independent of extracellular calcium and was not affected by tetrodotoxin (blocker of voltage dependent Na+ channels). In contrast, the halothane-evoked [3H]5-HT release was reduced by BAPTA-AM, a membrane-permeable BAPTA analog that chelates intracellular Ca2+. The anesthetic-induced [3H]5-HT release depends on the ryanodine-sensitive intracellular calcium store since it was blocked by dantrolene and azumolene (inhibitors of the calcium-release through ryanodine receptors) but was not affected by aminoethoxydiphenylborate (2-APB), an inhibitor of inositol 1,4,5-triphosphate receptor. The [3H]5-HT release induced by halothane comes mainly from the vesicular pool since it was reduced in about 70% by reserpine, a blocker of vesicular monoamine transporter. The halothane-evoked release of [3H]5-HT release is reduced by fluoxetine, an inhibitor of 5-HT uptake, and the volatile agent also decreased the uptake of [3H]5-HT into rat brain cortical slices. Moreover, a decrease on halothane-induced release of [3H]5-HT was also observed when the brain cortical slices were incubated at low temperature, which is known to interfere with the carrier-mediated release of the neurotransmitter. Ouabain, a Na+/K+ ATPase pump inhibitor, which induces 5-HT release through reverse transport, also decreased [3H]5-HT release induced by halothane, confirming the involvement of a carrier-mediated release of the neurotransmitter in the presence of halothane. In conclusion, these data suggest that halothane induces vesicular and carrier-mediated release of [3H]5-HT in rat brain cortical slices.     

New species of Hypolytrum Rich. (Cyperaceae) from the Neotropics

Five new species ofHypolytrum Rich. from South America are described and illustrated.Hypolytrum amorimii andH. jardimii, both of sect.Bullata T. Koyama, are species with pseudopetioles and colored leaves, and endemic to the rain forest of southeastern Brazil.Hypolytrum bahiense (sect.Hypolytrum), a species with a lax synflorescence and two, free and lightly scabridulous floral bracts, is endemic to the rain forest of southeastern Bahia, Brazil.Hypolytrum leptocalamum (sect.Hypolytrum), a species with lax synflorescence and spike ellipsoid to cylindrical, is restricted to area of tepuis in the Guayana Highland (Brazil, Guyana, and Venezuela).Hypolytrum paraense (sect.Hypolytrum), a species with three, partly connate and densely scabridulous floral bracts, is restricted to the rain forest of the Amazon Basin, in the state of Pará, Brazil.