Reactive oxygen and nitrogen species are involved in sorbitol-induced apoptosis of human erithroleukaemia cells K562

In this study, we found that production of both reactive oxygen (ROS) and nitrogen (RNS) species is a very early event related to treatment with hyperosmotic concentration of sorbitol. The production of nitric oxide (NO) was paralleled by the increase of the mRNA and protein level of the inducible form of the nitric oxide synthase (iNOS). ROS and RNS enhancement, process concomitant to the failure of mitochondrial trans-membrane potential (ΔΨ), was necessary for the induction of apoptosis as demonstrated by the protection against sorbitol-mediated toxicity observed after treatment with ROS scavengers or NOS inhibitors. The synergistic action of ROS and RNS was finally demonstrated by pre-treatment with rosmarinic acid that, by powerfully buffering both these species, prevents impairment of ΔΨ and cell death. Overall results suggest that the occurrence of apoptosis upon sorbitol treatment is an event mediated by oxidative/nitrosative stress rather than a canonical hyperosmotic shock.     

Molecular phylogeny and biogeography of the eastern Tapaculos (Aves: Rhinocryptidae: Scytalopus, Eleoscytalopus): Cryptic diversification in Brazilian Atlantic Forest

Scytalopus and the recently erected Eleoscytalopus are among the Neotropical groups of birds whose taxonomy is most difficult to resolve given their very conservative morphology. We investigated the phylogeny and species limits of Eleoscytalopus and the eastern Scytalopus using two mitochondrial genes and two nuclear introns of multiple individuals from all species of these groups. The eastern Scytalopus are separated in three well defined clades also supported by morphological or vocal characteristics, although the relationships between these clades could not be resolved. We found several allopatric and very divergent lineages in these genera whose characteristics are consistent with species-level divergence, especially in S. speluncae. The great divergence between E. psychopompus and its sister species supports the former as a valid species. Our results corroborate the importance of the Bahia refuge as an avian center of endemism.     

Regulation of Gdnf expression by retinoic acid in Sertoli cells

Glial cell line‐derived neurotrophic factor (GDNF) and retinoic acid (RA) are two molecules crucial for the regulation of the spermatogonial compartment of the testis. During the cycle of the seminiferous epithelium, their relative concentration oscillates with lower GDNF levels in stages where RA levels are high. It has been recently shown that RA negatively regulates Gdnf expression but the mechanisms behind are so far unknown. Here, we show that RA directly downregulates Gdnf mRNA levels in primary murine Sertoli cells through binding of RARα to a novel DR5‐RARE on Gdnf promoter. Pharmacological inhibition and chromatin immunoprecipitation–quantitative polymerase chain reaction analysis suggested that the underlying mechanism involved histone deacetylase activity and epigenetic repression of Gdnf promoter upon RA treatment.     

Thinner bark increases sensitivity of wetter Amazonian tropical forests to fire

Understory fires represent an accelerating threat to Amazonian tropical forests and can, during drought, affect larger areas than deforestation itself. These fires kill trees at rates varying from < 10 to c. 90% depending on fire intensity, forest disturbance history and tree functional traits. Here, we examine variation in bark thickness across the Amazon. Bark can protect trees from fires, but it is often assumed to be consistently thin across tropical forests. Here, we show that investment in bark varies, with thicker bark in dry forests and thinner in wetter forests. We also show that thinner bark translated into higher fire‐driven tree mortality in wetter forests, with between 0.67 and 5.86 gigatonnes CO₂ lost in Amazon understory fires between 2001 and 2010. Trait‐enabled global vegetation models that explicitly include variation in bark thickness are likely to improve the predictions of fire effects on carbon cycling in tropical forests.     

Characterization,Toxicity, and Optimization for the Growth and Production of Bacteriocin-like Substances by Lactobacillus curvatus

Probiotics and Antimicrobial Proteins - This study aimed to characterize, evaluate toxicity and optimize the conditions for the growth and production of bacteriocin-like substances by Lactobacillus...     

Ecological specialization and niche overlap of subterranean rodents inferred from DNA metabarcoding diet analysis

Knowledge of how animal species use food resources available in the environment can increase our understanding of many ecological processes. However, obtaining this information using traditional methods is difficult for species feeding on a large variety of food items in highly diverse environments. We amplified the DNA of plants for 306 scat and 40 soil samples, and applied an environmental DNA metabarcoding approach to investigate food preferences, degree of diet specialization and diet overlap of seven herbivore rodent species of the genus Ctenomys distributed in southern and midwestern Brazil. The metabarcoding approach revealed that these species consume more than 60% of the plant families recovered in soil samples, indicating generalist feeding habits of ctenomyids. The family Poaceae was the most common food resource retrieved in scats of all species as well in soil samples. Niche overlap analysis indicated high overlap in the plant families and molecular operational taxonomic units consumed, mainly among the southern species. Interspecific differences in diet composition were influenced, among other factors, by the availability of resources in the environment. In addition, our results provide support for the hypothesis that the allopatric distributions of ctenomyids allow them to exploit the same range of resources when available, possibly because of the absence of interspecific competition.     

A trait-based approach predicting community assembly and dominance of microbial invasive species

Understanding the mechanisms underlying community assembly helps to define success and susceptibility to biological invasions. Here, we explored phytoplankton community assembly following niche and neutral paradigms and using a trait-based approach. Under the hypothesis that the morphology-based functional groups (MBFG) clusters species with similar niche, we analysed how trait-related differences in fitness influence dominance of an invasive species. This was based on literature review, field data and model simulations. We predict that invading species can be dominant if: 1) do not belong to the local MBFG but use unexploited areas of the niche, or 2) belong to the resident MBFG but exhibit a higher fitness due to a particular combination of traits. The invasive dinoflagellate Ceratium furcoides was used as the model species to evaluate these hypotheses, its morphological (e.g. volume) and physiological (e.g. growth rates) traits were compared with species from the same (V: photosynthetic flagellates) and different (VII: colonial cyanobacteria) MBFG. Fitness was estimated using models parametrized with MBFG rates (R*, ability to draw down phosphate) under different environmental conditions (i.e. flushing). Results contributed to support both hypotheses. First, the alternation of C. furcoides and cyanobacteria dominance was explained by the use of different niches. Secondly, species from MBFG V were dominant under similar environments. Within this group V C. furcoides showed higher fitness under low flushing and high predation, advantage provided by a distinctive combination of traits. The application of trait-based approaches to represent the niche and estimate fitness along environmental gradients was useful to evaluate community assembly and can be used to predict the dominance of microbial species invasions.