Evidences for genetic differentiation within the highly endemic and endangered annual fish Austrolebias nigrofasciatus (Cyprinodontiformes: Rivulidae)

Samples of Austrolebias nigrofasciatus (n = 103), an endangered species of annual fish endemic to a small area of the Patos-Mirim lagoon system encompassing the São Gonçalo Channel lowlands, were collected from eight isolated temporary ponds, four located at the known distribution range of the species and four located along the Piratini River lowlands, where morphologically different individuals were found. In the laboratory, fragments of the mitochondrial cytochrome c oxidase I (coI), cytochrome b (cytb) and nuclear rhodopsin (rho) genes were amplified, purified and sequenced for 100, 99 and 58 of these individuals, respectively. Samples were further analysed using phylogenetic and phylogeographic methods to evaluate the patterns of genetic diversity and differentiation presented within and between populations, while assessing their evolutionary history, in order to guide the application of further conservation strategies. We found that the four new populations from the Piratini River lowlands encompass a different lineage of A. nigrofasciatus that diverged from that encountered in the São Gonçalo Channel at approximately 0.165 M years before present, during a population expansion and did not yet attain reciprocal monophyly. This divergence was associated with a glacial event that was preceded by an interglacial period putatively associated with the dispersal. Moreover, significant levels of genetic differentiation and a high number of exclusive haplotypes could be encountered even in micro-geographical scales, as in the comparisons between populations located within the same major lineage, indicating each of them may encompass independent management units. Conservation actions are certainly urgent, especially in the face of signs of a recent bottleneck.     

Volume density of syncytial sprouts and its regional variation in the human mature placenta

The authors studied by means of sterological methods the volume density of syncytial sprouts in different cotyledonary regions of the human term placenta. The syncytial sprouts account for 4.92% of the placenta volume. Meanwhile, there were significant differences according to the site from which the sample was obtained. The lowest value (2.72%) corresponds to the central-parabasal zone of the cotyledon, close to the entry of the maternal blood into the intervillous space, whereas the highest values correspond to the "venous" regions. The results of the present study, as well as those reported by others, suggest that the lateral-subchorial zone would be the growing region of the cotyledon.     

gp120-independent fusion mediated by the human immunodeficiency virus type 1 gp41 envelope glycoprotein: a reassessment.

In a natural context, membrane fusion mediated by the human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins involves both the exterior envelope glycoprotein (gp120) and the transmembrane glycoprotein (gp41). Perez et al. (J. Virol. 66:4134-4143, 1992) reported that a mutant HIV-1 envelope glycoprotein containing only the signal peptide and carboxyl terminus of the gp120 exterior glycoprotein fused to the complete gp41 glycoprotein was properly cleaved and that the resultant gp41 glycoprotein was able to induce the fusion of even CD4-negative cells. In the studies reported herein, mutant proteins identical or similar to those studied by Perez et al. lacked detectable cell fusion activity. The proteolytic processing of these proteins was very inefficient, and one processed product identified by Perez et al. as the authentic gp41 glycoprotein was shown to contain carboxyl-terminal gp120 sequences. Furthermore, no fusion activity was observed for gp41 glycoproteins exposed after shedding of the gp120 glycoprotein by soluble CD4. Thus, evidence supporting a gp120-independent cell fusion activity for the HIV-1 gp41 glycoprotein is currently lacking.     

Study of the Biological Activity and Phenolic Content of the Ethanol Extract of Phyllogonium viride Brid. (Phyllogoniaceae,Bryophyta)

The present study aimed to examine the phenolic content and evaluate the antimicrobial and antioxidant potential of ethanol extracts from the moss species Phyllogonium viride Brid. on the pathogenic bacteria Salmonella enterica serovar enteritidis, Staphylococcus aureus, Listeria monocytogenes and Escherichia coli, and the pathogenic fungi Candida albicans and Cryptococcus neoformans. The antimicrobial activity was determined from Minimum Inhibitory Concentration (MIC) Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC). Antioxidant activity was determined by the DPPH method. Folin-Denis reagent was used for the content of total phenolics and flavonoids and HPLC-DAD for identification of phenolic compounds. The results showed that bacteriostatic and bactericidal activities occurred at concentrations ranging from 9.76 μg/mL–78.13 μg/mL among all evaluated microorganisms. These values, considering the criteria used, suggest the P. viride extract as a potent antimicrobial. For antioxidant activity, P. viride extract was considered weak. Analysis of the phenolic content showed a wide range of compounds, with Kaempferol (0.41 mg/g) being the major compound, followed by t-cinnamic acid and caffeic acid (0.17 mg/g). Although P. viride is a species of moss not yet referenced in scientific publications of biotechnological interest, it has shown promising potential for further studies and possible application as an antimicrobial of natural origin.     

Retinol (Vitamin A) Increases α-Synuclein, β-Amyloid Peptide,Tau Phosphorylation and RAGE Content in Human SH-SY5Y Neuronal Cell Line

Retinoids (vitamin A and derivatives) are recognized as essential factors for central nervous system (CNS) development. Retinol (vitamin A) also was postulated to be a major antioxidant component of diet as it modulates reactive species (RS) production and oxidative stress in biological systems. Oxidative stress plays a major role either in pathogenesis or development of neurodegenerative diseases, or even in both. Here we investigate the role of retinol supplementation to human neuron-derived SH-SY5Y cells over RS production and biochemical markers associated to neurodegenerative diseases expressed at neuronal level in Parkinson’s disease and Alzheimer’s disease: α-synuclein, β-amyloid peptide, tau phosphorylation and RAGE. Retinol treatment (24 h) impaired cell viability and increased intracellular RS production at the highest concentrations (7 up to 20 µM). Antioxidant co-treatment (Trolox 100 µM) rescued cell viability and inhibited RS production. Furthermore, retinol (10 µM) increased the levels of α-synuclein, tau phosphorylation at Ser396, β-amyloid peptide and RAGE. Co-treatment with antioxidant Trolox inhibited the increased in RAGE, but not the effect of retinol on α-synuclein, tau phosphorylation and β-amyloid peptide accumulation. These data indicate that increased availability of retinol to neurons at levels above the cellular physiological concentrations may induce deleterious effects through diverse mechanisms, which include oxidative stress but also include RS-independent modulation of proteins associated to progression of neuronal cell death during the course of neurodegenerative diseases.     

Contrasted histories of organelle and nuclear genomes underlying physiological diversification in a grass species

C₄ photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photosynthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this species encompasses C₄ and non-C₄ populations. Using phylogenomics and population genomics, we infer the history of dispersal and secondary gene flow before, during and after photosynthetic divergence in A. semialata. We further analyse the genome composition of individuals with varied ploidy levels to establish the origins of polyploids in this species. Detailed organelle phylogenies indicate limited seed dispersal within the mountainous region of origin and the emergence of a C₄ lineage after dispersal to warmer areas of lower elevation. Nuclear genome analyses highlight repeated secondary gene flow. In particular, the nuclear genome associated with the C₄ phenotype was swept into a distantly related maternal lineage probably via unidirectional pollen flow. Multiple intraspecific allopolyploidy events mediated additional secondary genetic exchanges between photosynthetic types. Overall, our results show that limited dispersal and isolation allowed lineage divergence, with photosynthetic innovation happening after migration to new environments, and pollen-mediated gene flow led to the rapid spread of the derived C₄ physiology away from its region of origin.     

Follicular growth and sex steroids in adult females of the endemic Amazonian freshwater stingray Potamotrygon wallacei (Chondrichthyes,Potamotrygonidae)

Environmental Biology of Fishes - This study evaluated how the plasma steroid hormones testosterone (T) and 17β-estradiol (E2) are related to follicular development in regenerating females of...     

Developing of a model to predict lying behavior of dairy cows on silvopastoral system during the winter season

International Journal of Biometeorology - Lying behavior is an important indicator of the cows’ welfare and health. In this study, we evaluate the effect of the physical environment on dairy...