Reduction in number of sarcolemmal KATP channels slows cardiac action potential duration shortening under hypoxia

The cardiovascular system operates under demands ranging from conditions of rest to extreme stress. One mechanism of cardiac stress tolerance is action potential duration shortening driven by ATP-sensitive potassium (K_ATP) channels. K_ATP channel expression has a significant physiologic impact on action potential duration shortening and myocardial energy consumption in response to physiologic heart rate acceleration. However, the effect of reduced channel expression on action potential duration shortening in response to severe metabolic stress is yet to be established. Here, transgenic mice with myocardium-specific expression of a dominant negative K_ATP channel subunit were compared with littermate controls. Evaluation of K_ATP channel whole cell current and channel number/patch was assessed by patch clamp in isolated ventricular cardiomyocytes. Monophasic action potentials were monitored in retrogradely perfused, isolated hearts during the transition to hypoxic perfusate. An 80–85% reduction in cardiac K_ATP channel current density results in a similar magnitude, but significantly slower rate, of shortening of the ventricular action potential duration in response to severe hypoxia, despite no significant difference in coronary flow. Therefore, the number of functional cardiac sarcolemmal K_ATP channels is a critical determinant of the rate of adaptation of myocardial membrane excitability, with implications for optimization of cardiac energy consumption and consequent cardioprotection under conditions of severe metabolic stress.     

Cell recruitment and cytokines in skin mice sensitized with the vaccine adjuvants: saponin, incomplete Freund's adjuvant, and monophosphoryl lipid A

Vaccine adjuvants are substances associated with antigens that are fundamental to the formation of an intense, durable, and fast immune response. In this context, the use of vaccine adjuvants to generate an effective cellular immune response is crucial for the design and development of vaccines against visceral leishmaniasis. The objective of this study was to evaluate innate inflammatory response induced by the vaccine adjuvants saponin (SAP), incomplete Freund's adjuvant (IFA), and monophosphoryl lipid A (MPL). After a single dose of adjuvant was injected into the skin of mice, we analyzed inflammatory reaction, selective cell migration, and cytokine production at the injection site, and inflammatory cell influx in the peripheral blood. We found that all vaccine adjuvants were able to promote cell recruitment to the site without tissue damage. In addition, they induced selective migration of neutrophils, macrophages, and lymphocytes. The influx of neutrophils was notable at 12 h in all groups, but at other time points it was most evident after inoculation with SAP. With regard to cytokines, the SAP led to production of interleukin (IL)-2, IL-6, and IL-4. IFA promoted production of tumor necrosis factor (TNF)-α, interferon (IFN)-γ, IL-6, IL-17, IL-4, and IL-10. We also observed that MPL induced high production of IL-2, TNF-α, and IFN-γ, in addition to IL-6, IL-17, and IL-10. In peripheral blood, values of certain cell populations in the local response changed after stimulation. Our data demonstrate that the three vaccine adjuvants stimulate the early events of innate immune response at the injection site, suggesting their ability to increase the immunogenicity of co-administered antigens. Moreover, this work provides relevant information about elements of innate and acquired immune response induced by vaccine adjuvants administered alone.     

Ethanol-Induced Oxidative Stress: The Role of Binaphthyl Diselenide as a Potent Antioxidant

It is widely accepted that oxidative stress plays a central role in alcohol-induced pathogenesis. The protective effect of binaphthyl diselenide (NapSe)2 was investigated in ethanol (Etoh)-induced brain injury. Thirty male adult Wistar rats were divided randomly into five groups of six animals each and treated as follows: (1) The control group received the vehicle (soy bean oil, 1 mL/kg, p.o.). (2) Ethanol group of animals was administered with ethanol (70% v/v, 2 mL/kg, p.o.). (3) (NapSe)2 1 mg/kg, 1 mL/kg plus ethanol 70% (v/v, 2 mL/kg, p.o. (5) (NapSe)2 10 mg/kg, 1 mL/kg) plus ethanol 70% (v/v, 2 mL/kg, p.o). After acute treatment, all rats were sacrificed by decapitation. Evidence for oxidative stress in rat brain was obtained from the observed levels of thiobarbituric acid reactive species, of non-protein thiol (NPSH) groups, and of ascorbic acid, as well as from the activities of catalase (CAT) and of superoxide dismutase (SOD). (NapSe)2 compensated the deficits in the antioxidant defense mechanisms (CAT, SOD, NPSH, and ascorbic acid), and suppressed lipid peroxidation in rat brain resulting from Etoh administration. It was concluded that ethanol exposure causes alterations in the antioxidant defense system and induces oxidative stress in rat brain. (NaPSe)2 at 5 mg/kg restored the antioxidant defenses in rat brain and mitigated the toxic effects of alcohol, suggesting that could be used as a potential therapeutic agent for alcohol-induced oxidative damage in rat brain.     

Clinanthus microstephium,an Amaryllidaceae Species with Cholinesterase Inhibitor Alkaloids: Structure−Activity Analysis of Haemanthamine Skeleton Derivatives

Plants of the Amaryllidaceae family are well‐known (not only) for their ornamental value but also for the alkaloids that they produce. In this report, the first phytochemical study of Clinanthus genus was carried out. The chemical composition of alkaloid fractions from Clinanthus microstephium was analyzed by GC/MS and NMR. Seven known compounds belonging to three structural types of Amaryllidaceae alkaloids were identified. An epimeric mixture of a haemanthamine‐type compound (6‐hydroxymaritidine) was tested as an inhibitor against acetyl‐ and butyrylcholinesterase enzymes (AChE and BChE, respectively), two enzymes relevant in the treatment of Alzheimer's disease, with good results. Structure–activity relationships through molecular docking studies with this alkaloid and other structurally related compounds were discussed.     

Evidence for rare recombination at the gametophytic self-incompatibility locus

The gametophytic self-incompatibility locus has been thought to be a nonrecombining genomic region. Inferences have been made, however, about the functional importance of different parts of the S-locus, based on differences in the levels of variability along the gene, and this is valid only if recombination occurs. It is thus important to test whether recombination occurs within and near the S-locus. Several recent attempts to test this have reached conflicting conclusions. In this study, we examine a large data set on sequence variation at the S-locus in several species with gametophytic self-incompatibility systems, in the Solanaceae, Rosaceae and Scrophulariaceae. We use the longest sequences available to test for recombination based on linkage disequilibrium between polymorphic sites in the S-locus. The relationship between linkage disequilibrium and physical distance between the sites suggests rare intragenic exchange in the evolutionary history of four species of Solanaceae and two species of Rosaceae.     

Systematic review of Atractus schach (Serpentes: Dipsadidae) species complex from the Guiana Shield with description of three new species

The Guiana Shield harbours one of the best preserved and largest extents of tropical forest on Earth and an immense biodiversity. The herpetofauna of this region remains poorly known. The species-rich snake genus Atractus contains ～140 species, many with complicated taxonomic histories, including A. schach. Examination of specimens in museums and newly collected material from French Guiana has allowed the illustration of hemipenial morphology for the first time and an expanded diagnosis. Concatenated molecular phylogenetic (mitochondrial and nuclear genes) and phenotypic (morphometrics, external and hemipenial morphology) analyses confirm non-monophyly of the A. flammigerus group and indicate that A. schach is a species complex with three new species described here. The geographic distribution of A. schach sensu stricto is restricted to Guiana, Surinam, and French Guiana north of Tumucumaque massif. Populations tentatively assigned to A. schach from the east from French Guiana in the Roura lowlands to Almeirim, and from central Amazonia between the Negro and Trombetas rivers in Brazil are also recognized as new species. Our results suggest that populations from south of the Amazon River are not conspecific with those from the Guiana Shield.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:A7AE40BC-4716-4302-B3BE-1F43600B0A72     

Post-translational modifications in MeHg-induced neurotoxicity

Mercury (Hg) exposure remains a major public health concern due to its widespread distribution in the environment. Organic mercurials, such as MeHg, have been extensively investigated especially because of their congenital effects. In this context, studies on the molecular mechanism of MeHg-induced neurotoxicity are pivotal to the understanding of its toxic effects and the development of preventive measures. Post-translational modifications (PTMs) of proteins, such as phosphorylation, ubiquitination, and acetylation are essential for the proper function of proteins and play important roles in the regulation of cellular homeostasis. The rapid and transient nature of many PTMs allows efficient signal transduction in response to stress. This review summarizes the current knowledge of PTMs in MeHg-induced neurotoxicity, including the most commonly PTMs, as well as PTMs induced by oxidative stress and PTMs of antioxidant proteins. Though PTMs represent an important molecular mechanism for maintaining cellular homeostasis and are involved in the neurotoxic effects of MeHg, we are far from understanding the complete picture on their role, and further research is warranted to increase our knowledge of PTMs in MeHg-induced neurotoxicity.     

The freshwater planarian Dugesia (G.) tigrina contains a great diversity of homeobox genes

To identify potential pattern control and cell determination and/or differentiation genes in the freshwater planarian Dugesial (G.) tigrina, we searched for homeobox genes of different types in the genome of this primitive metazoan. We applied two basic approaches: 1) Screening the cDNA library with degenerate oligonucleotides corresponding to the most conserved amino acid sequence from helix-3 of the homeodomain of each family; and 2) PCR amplification of genomic DNA or cDNA, using two sets of degenerated oligonucleotides corresponding to helices 1 and 3 of the homeodomain or two specific domains of the POU family. Using the first strategy we have identified and characterized two tissue-specific cell determination and/or differentiation NK-type homeobox genes. Using the second strategy we have identified several homeobox genes that belong to the HOM/Hox, paired (prd) or POU families.     

The digestive tube of Piaractus brachypomus: gross morphology,histology/histochemistry of the mucosal layer and the effects of parasitism by Neoechinorhynchus sp.

The objective of the present study was to describe the histology and histochemistry of the mucosal layer of the digestive tube of Piaractus brachypomus, and the histopathology associated with parasitism by Neoechinorhynchus sp. The digestive tube of P. brachypomus consists of three macroscopically distinct portions: short, rectilinear and elastic-walled ooesophagus, J-shaped siphon stomach and a long intestine with rectilinear and curved portions, defined by patterns of villi as foregut, midgut, and hindgut. Histological and histochemical differences were observed in the mucosal layers of the different digestive tube regions, such as intense production of neutral and acidic mucous substances in the pseudostratified mucosal epithelium of the oesophagus; positive periodic acid Schiff reagent (PAS)reactions at the apex of the columnar epithelial cells of the stomach and increased intensity of histochemical reactions in the hindgut region. Neoechinorhynchus sp. was present in 85.7% of specimens examined, with a mean intensity of 7.4 ± 6.2 (±) and abundance of 6.33. Good health of the fish indicated by high relative condition factor values ( _Kn) and occurrence of only mild to moderate alteration in the mucosal layer indicated that Neoechinorhynchus sp. exhibits low pathogenicity towards P. brachypomus hosts in farming environments, with low levels of infection.     

An important step forward for the future development of an easy and fast procedure for identifying the most dangerous wine spoilage yeast,Dekkera bruxellensis,in wine environment

Dekkera bruxellensis is the main reason for spoilage in the wine industry. It renders the products unacceptable leading to large economic losses. Fluorescence In Situ Hybridization (FISH) technique has the potential for allowing its specific detection. Nevertheless, some experimental difficulties can be encountered when FISH technique is applied in the wine environment (e.g. matrix and cells’ autofluorescence, fluorophore inadequate selection and probes’ low specificity to the target organisms). An easy and fast in-suspension RNA-FISH procedure was applied for the first time for identifying D. bruxellensis in wine. A previously designed RNA-FISH probe to detect D. bruxellensis (26S D. brux.5.1) was used, and the matrix and cells’ fluorescence interferences, the influence of three fluorophores in FISH performance and the probe specificity were evaluated. The results revealed that to apply RNA-FISH technique in the wine environment, a red-emitting fluorophore should be used. Good probe performance and specificity were achieved with 25% of formamide. The resulting RNA-FISH protocol was applied in wine samples artificially inoculated with D. bruxellensis. This spoilage microorganism was detected in wine at cell densities lower than those associated with phenolic off-flavours. Thus, the RNA-FISH procedure described in this work represents an advancement to facilitate early detection of the most dangerous wine spoilage yeast and, consequently, to reduce the economic losses caused by this yeast to the wine industry.