Abiotic factors and trophic interactions affect the macroinvertebrate community of bromeliad tanks in a Neotropical Restinga

Limnology - Aquatic macroinvertebrate communities are dependent on intrinsic environmental characteristics and biological interactions in microhabitat systems. We investigated the...     

Cannabidiol inhibits the skeletal muscle Nav1.4 by blocking its pore and by altering membrane elasticity

Cannabidiol (CBD) is the primary nonpsychotropic phytocannabinoid found in Cannabis sativa, which has been proposed to be therapeutic against many conditions, including muscle spasms. Among its putative targets are voltage-gated sodium channels (Navs), which have been implicated in many conditions. We investigated the effects of CBD on Nav1.4, the skeletal muscle Nav subtype. We explored direct effects, involving physical block of the Nav pore, as well as indirect effects, involving modulation of membrane elasticity that contributes to Nav inhibition. MD simulations revealed CBD’s localization inside the membrane and effects on bilayer properties. Nuclear magnetic resonance (NMR) confirmed these results, showing CBD localizing below membrane headgroups. To determine the functional implications of these findings, we used a gramicidin-based fluorescence assay to show that CBD alters membrane elasticity or thickness, which could alter Nav function through bilayer-mediated regulation. Site-directed mutagenesis in the vicinity of the Nav1.4 pore revealed that removing the local anesthetic binding site with F1586A reduces the block of I_Na by CBD. Altering the fenestrations in the bilayer-spanning domain with Nav1.4-WWWW blocked CBD access from the membrane into the Nav1.4 pore (as judged by MD). The stabilization of inactivation, however, persisted in WWWW, which we ascribe to CBD-induced changes in membrane elasticity. To investigate the potential therapeutic value of CBD against Nav1.4 channelopathies, we used a pathogenic Nav1.4 variant, P1158S, which causes myotonia and periodic paralysis. CBD reduces excitability in both wild-type and the P1158S variant. Our in vitro and in silico results suggest that CBD may have therapeutic value against Nav1.4 hyperexcitability.     

Immunologic evaluation and validation of methods using synthetic peptides derived from Mycobacterium tuberculosis for the diagnosis of tuberculosis infection

The goal of this study was to demonstrate the usefulness of an enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of pulmonary tuberculosis (PTB) and extrapulmonary TB (EPTB). This assay used 20 amino acid-long, non-overlapped synthetic peptides that spanned the complete Mycobacterium tuberculosis ESAT-6 and Ag85A sequences. The validation cohort consisted of 1,102 individuals who were grouped into the following five diagnostic groups: 455 patients with PTB, 60 patients with EPTB, 40 individuals with non-EPTB, 33 individuals with leprosy and 514 healthy controls. For the PTB group, two ESAT-6 peptides (12033 and 12034) had the highest sensitivity levels of 96.9% and 96.2%, respectively, and an Ag85A-peptide (29878) was the most specific (97.4%) in the PTB groups. For the EPTB group, two Ag85A peptides (11005 and 11006) were observed to have a sensitivity of 98.3% and an Ag85A-peptide (29878) was also the most specific (96.4%). When combinations of peptides were used, such as 12033 and 12034 or 11005 and 11006, 99.5% and 100% sensitivities in the PTB and EPTB groups were observed, respectively. In conclusion, for a cohort that consists entirely of individuals from Venezuela, a multi-antigen immunoassay using highly sensitive ESAT-6 and Ag85A peptides alone and in combination could be used to more rapidly diagnose PTB and EPTB infection.     

PEG conjugates of potent α4 integrin inhibitors,maintaining sustained levels and bioactivity in vivo,following subcutaneous administration

Mitsunobu reactions were employed to link t-butyl esters of α4 integrin inhibitors at each of the termini of a three-arm, 40 kDa, branched PEG. Cleavage of the t-butyl esters using HCO₂H provided easily isolated PEG derivatives, which are potent α4 integrin inhibitors, and which achieve sustained levels and bioactivity in vivo, following subcutaneous administration to rats.     

Amphibian skin fungal communities vary across host species and do not correlate with infection by a pathogenic fungus

Amphibian population declines caused by the fungus Batrachochytrium dendrobatidis (Bd) have prompted studies on the bacterial community that resides on amphibian skin. However, studies addressing the fungal portion of these symbiont communities have lagged behind. Using ITS1 amplicon sequencing, we examined the fungal portion of the skin microbiome of temperate and tropical amphibian species currently coexisting with Bd in nature. We assessed cooccurrence patterns between bacterial and fungal OTUs using a subset of samples for which bacterial 16S rRNA gene amplicon data were also available. We determined that fungal communities were dominated by members of the phyla Ascomycota and Basidiomycota, and also by Chytridiomycota in the most aquatic amphibian species. Alpha diversity of the fungal communities differed across host species, and fungal community structure differed across species and regions. However, we did not find a correlation between fungal diversity/community structure and Bd infection, though we did identify significant correlations between Bd and specific OTUs. Moreover, positive bacterial–fungal cooccurrences suggest that positive interactions between these organisms occur in the skin microbiome. Understanding the ecology of amphibian skin fungi, and their interactions with bacteria will complement our knowledge of the factors influencing community assembly and the overall function of these symbiont communities.     

Three-dimensional structure determination of capsid of<Emphasis Type="Italic">Aedes albopictus</Emphasis> C6/36 cell densovirus

The three-dimensional structure of capsid ofAedes albopictus C6/36 densovirus was determined to 14-Å resolution by electron cryomicroscopy and computer reconstruction. The triangulation number of the capsid is 1. There are 12 holes in each triangular face and a spike on each 5-fold vertex. The validity of the capsid and nucleic acid densities in the reconstructions was discussed.     

The apoprotein is the preferential target for peroxynitrite-induced LDL damage protection by dietary phenolic acids

Peroxynitrite has been shown to modify low-density lipoproteins (LDL) into a form recognized by the macrophage scavenger receptor, suggesting that it may play a significant role in atherogenesis. Considering that the mechanisms underlying LDL modifications by this agent have not been well elucidated, the aim of this study was to characterize the chemical modifications of either the lipid or the protein moieties mediated by synthesized peroxynitrite (preformed) or formed in situ by SIN-1, and evaluate the protective effects of some dietary phenolic acids. Preformed peroxynitrite does not induce LDL lipid peroxidation, as assessed either by formation of conjugated diene isomers or degradation of fatty acids and cholesteryl esters, although a rapid loss of alpha-tocopherol content occurs. Also, peroxynitrite formed in situ induces only a slight lipid oxidation. In contrast, under conditions where the LDL lipid moiety is not significantly oxidized, peroxynitrite either preformed or formed in situ rapidly elicit significant LDL apoprotein modifications, as evaluated by an increase in carbonyl groups formation and by great decrease in intrinsic tryptophan and thiol groups, in a concentration-dependent manner, that are accompanied by an increase in the LDL net negative charge, leading to an increase in electrophoretic mobility. Phenolic acids, namely caffeic, chlorogenic and ferulic, inhibit all these processes in a concentration dependent way, being the catechols the most efficient. UV spectral analysis of phenols upon interaction with peroxynitrite suggest that, in our assay conditions, such protection is related with the scavenging of this agent by either electron donation for the catechols, caffeic and chlorogenic acids, or nitration for the monophenol ferulic acid. Our data point that in contrast with other physiological oxidants, as ferrylmyoglobin or copper, peroxynitrite triggers the rapid damage to LDL primarily by protein and not lipid oxidation, and that such process is inhibited by dietary phenolic derivatives of cinnamic acids.     

Adaptive Potential of Hybridization among Malaria Vectors: Introgression at the Immune Locus TEP1 between Anopheles coluzzii and A. gambiae in ‘Far-West’ Africa

“Far-West” Africa is known to be a secondary contact zone between the two major malaria vectors Anopheles coluzzii and A. gambiae. We investigated gene-flow and potentially adaptive introgression between these species along a west-to-east transect in Guinea Bissau, the putative core of this hybrid zone. To evaluate the extent and direction of gene flow, we genotyped site 702 in Intron-1 of the para Voltage-Gated Sodium Channel gene, a species-diagnostic nucleotide position throughout most of A. coluzzii and A. gambiae sympatric range. We also analyzed polymorphism in the thioester-binding domain (TED) of the innate immunity-linked thioester-containing protein 1 (TEP1) to investigate whether elevated hybridization might facilitate the exchange of variants linked to adaptive immunity and Plasmodium refractoriness. Our results confirm asymmetric introgression of genetic material from A. coluzzii to A. gambiae and disruption of linkage between the centromeric "genomic islands" of inter-specific divergence. We report that A. gambiae from the Guinean hybrid zone possesses an introgressed TEP1 resistant allelic class, found exclusively in A. coluzzii elsewhere and apparently swept to fixation in West Africa (i.e. Mali and Burkina Faso). However, no detectable fixation of this allele was found in Guinea Bissau, which may suggest that ecological pressures driving segregation between the two species in larval habitats in this region may be different from those experienced in northern and more arid parts of the species’ range. Finally, our results also suggest a genetic subdivision between coastal and inland A. gambiae Guinean populations and provide clues on the importance of ecological factors in intra-specific differentiation processes.