Cysteamine prevents and reverses the inhibition of creatine kinase activity caused by cystine in rat brain cortex

Cystinosis is a disorder associated with lysosomal cystine accumulation caused by defective cystine efflux. Cystine accumulation provokes a variable degree of symptoms depending on the involved tissues. Adult patients may present brain cortical atrophy. However, the mechanisms by which cystine is toxic to the tissues are not fully understood. Considering that brain damage may be developed by energy deficiency, creatine kinase is a thiolic enzyme crucial for energy homeostasis, and disulfides like cystine may alter thiolic enzymes by thiol/disulfide exchange, the main objective of the present study was to investigate the effect of cystine on creatine kinase activity in total homogenate, cytosolic and mitochondrial fractions of the brain cortex from 21-day-old Wistar rats. We performed kinetic studies and investigated the effects of GSH, a biologically occurring thiol group protector, and cysteamine, the drug used for cystinosis treatment, to better understand the effect of cystine on creatine kinase activity. Results showed that cystine inhibited the enzyme activity non-competitively in a dose- and time-dependent way. GSH partially prevented and reversed CK inhibition caused by cystine and cysteamine fully prevented and reversed this inhibition, suggesting that cystine inhibits creatine kinase activity by interaction with the sulfhydryl groups of the enzyme. Considering that creatine kinase is a crucial enzyme for brain cortex energy homeostasis, these results provide a possible mechanism for cystine toxicity and also a new possible beneficial effect for the use of cysteamine in cystinotic patients.     

Biogeography and priority areas for the conservation of bats in the Brazilian Cerrado

In this study, we describe the distribution pattern of bat species and select priority areas for the conservation of the Cerrado based on a systematic planning approach. We estimated species richness and calculated the total beta diversity based on Sørensen’s dissimilarity index (βsor). We estimated the species turnover using Simpson’s dissimilarity index (βsim). We then evaluated the nesting (βsne) by the difference between the dissimilarity indices (βsor and βsim). Based on this analysis, we identified the priority areas for the conservation of bats in the Cerrado based on the zonation approach. We found that the species richness and beta diversity of bats in the Cerrado are concentrated primarily in the central and northern portions of the biome. We also discovered that the conservation units of the Cerrado are ineffective for the protection of species with a restricted distribution (≤ 150 grid cells), such as Vampyrum spectrum, for which we propose the creation of new conservation units that better cover the diversity patterns observed in the present study. By conserving this diversity, we will also be protecting local habitats, which will in turn enable the survival of a wide range of species, and provide the ecosystems with the capacity to respond adequately to future changes in the environment.     

Interactions of cantharidin-like inhibitors with human protein phosphatase-5 in a Mg<Superscript>2+</Superscript> system: molecular dynamics and quantum calculations

The serine/threonine protein phosphatase type 5 (PP5) is a promising target for designing new antitumor drugs. This enzyme is a member of the PPP phosphatases gene family, which catalyzes a dephosphorylation reaction: a regulatory process in the signal transduction pathway that controls various biological processes. The aim of this work is to study and compare the inhibition of PP5 by ten cantharidin-like inhibitors in order to bring about contributions relevant to the better comprehension of their inhibitory activity. In this theoretical investigation, we used molecular dynamics techniques to understand the role of key interactions that occur in the protein active site; QM calculations were employed to study the interaction mode of these inhibitors in the enzyme. In addition, atoms in molecules (AIM) calculations were carried out to characterize the chemical bonds among the atoms involved and investigate the orbital interactions with their respective energy values. The obtained results suggest that the Arg275, Asn303, His304, His352, Arg400, His427, Glu428, Val429, Tyr451, and Phe446 residues favorably contribute to the interactions between inhibitors and PP5. However, the Asp271 and Asp244 amino acid residues do not favor such interactions for some inhibitors. Through the QM calculations, we can suggest that the reactional energy of the coordination mechanism of these inhibitors in the PP5 active site is quite important and is responsible for the inhibitory activity. The AIM technique employed in this work was essential to get a better comprehension of the transition states acquired from the mechanism simulation. This work offers insights of how cantharidin-like inhibitors interact with human PP5, potentially allowing the design of more specific and even less cytotoxic drugs for cancer treatments.

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Graphical Abstract Interactions of cantharidin-like inhibitors with human protein phosphatase-5 in a Mg²⁺ system

     

Indole-3-acetic acid in plant–microbe interactions

Indole-3-acetic acid (IAA) is an important phytohormone with the capacity to control plant development in both beneficial and deleterious ways. The ability to synthesize IAA is an attribute that many bacteria including both plant growth-promoters and phytopathogens possess. There are three main pathways through which IAA is synthesized; the indole-3-pyruvic acid, indole-3-acetamide and indole-3-acetonitrile pathways. This chapter reviews the factors that effect the production of this phytohormone, the role of IAA in bacterial physiology and in plant–microbe interactions including phytostimulation and phytopathogenesis.     

Interplay between neutrophils and trophoblast cells conditions trophoblast function and triggers vascular transformation signals

Normal placentation entails highly regulated interactions of maternal leukocytes with vascular and trophoblast cells to favor vascular transformation. Neutrophil activation and neutrophil extracellular trap (NET) formation associate with poor placentation and severe pregnancy complications. To deepen into the mechanisms of trophoblast–neutrophil interaction, we explored the effects of NETs on trophoblast cell function and, conversely, whether trophoblast cell-derived factors condition neutrophils to favor angiogenesis and anti-inflammatory signals required for fetal growth. NETs isolated from activated neutrophils hindered trophoblast cell migration. Trophoblast conditioned media prevented the effect as well as the vasoactive intestinal peptide (VIP) known to regulate trophoblast and neutrophil function. On the other hand, factors released by trophoblast cells and VIP shaped neutrophils to a proangiogenic profile with increased vascular endothelial growth factor synthesis and increased capacity to promote vascular transformation. Results presented here provide novel clues to reconstruct the interaction of trophoblast cells and neutrophils in vivo during placentation in humans.     

Heteroleptic oxidovanadium(IV)-malate complex improves glucose uptake in HepG2 and enhances insulin action in streptozotocin-induced diabetic rats

BioMetals - Diabetes mellitus, a complex and heterogeneous disease associated with hyperglycemia, is a leading cause of mortality and reduces life expectancy. Vanadium complexes have been studied...     

Invasional meltdown: an experimental test and a framework to distinguish synergistic,additive, and antagonistic effects

The potential role of positive interactions among co-invaders is at the core of the invasional meltdown hypothesis. The interaction of non-native species could result in an exacerbation of each other’s effects. Thus, the resulting effect of multiple non-native species on ecosystems can be greater than the sum of their individual effects. We designed an analytical framework and a set of mesocosm experiments to assess the potential synergistic effects of three non-native species (Limnoperna fortunei, Astronotus crassipinnis, and Hydrilla verticillata) in a highly invaded floodplain in southern Brazil. We analyzed ecosystem, community, and population attributes in scenarios with non-natives. Our hypothesis of a synergistic effect was not supported. Even though effects of the invasive species were detected for all ecological levels, evidence indicated that these effects were additive. In addition to adding to the statement that origin (i.e., native vs. non-native status) does matter, we provide a tool to differentiate additive, synergistic, and antagonistic effects in situations with multiple invasions, and experimentally demonstrate additive effects of non-native species at different ecological levels.

     

Role of Δ1-Pyrroline-5-Carboxylate Dehydrogenase Supports Mitochondrial Metabolism and Host-Cell Invasion of Trypanosoma cruzi

Proline is crucial for energizing critical events throughout the life cycle of Trypanosoma cruzi, the etiological agent of Chagas disease. The proline breakdown pathway consists of two oxidation steps, both of which produce reducing equivalents as follows: the conversion of proline to Δ¹-pyrroline-5-carboxylate (P5C), and the subsequent conversion of P5C to glutamate. We have identified and characterized the Δ¹-pyrroline-5-carboxylate dehydrogenase from T. cruzi (TcP5CDH) and report here on how this enzyme contributes to a central metabolic pathway in this parasite. Size-exclusion chromatography, two-dimensional gel electrophoresis, and small angle x-ray scattering analysis of TcP5CDH revealed an oligomeric state composed of two subunits of six protomers. TcP5CDH was found to complement a yeast strain deficient in PUT2 activity, confirming the enzyme''s functional role; and the biochemical parameters (K_m, k_cat, and k_cat/K_m) of the recombinant TcP5CDH were determined, exhibiting values comparable with those from T. cruzi lysates. In addition, TcP5CDH exhibited mitochondrial staining during the main stages of the T. cruzi life cycle. mRNA and enzymatic activity levels indicated the up-regulation (6-fold change) of TcP5CDH during the infective stages of the parasite. The participation of P5C as an energy source was also demonstrated. Overall, we propose that this enzymatic step is crucial for the viability of both replicative and infective forms of T. cruzi.     

Metabolic responses in two species of crayfish (Parastacus defossus and Parastacus brasiliensis) to post-hypoxia recovery

The period of post-hypoxia recovery is essential for the rapid replenishment of energy reserves and for the removal of metabolic end products formed during hypoxia. Periods of post-hypoxia recovery were analyzed in two crayfish species, where Parastacus defossus is a fossorial species, and Parastacus brasiliensis lives in lotic environments with higher oxygen levels. After 4 h of hypoxia (2 mg O(2)/L), groups of animals were placed in tanks with oxygenated water and were then removed at intervals of 1, 3, 6, and 9 h. Hemolymph and tissues (hepatopancreas, muscle, and anterior and posterior gills) were extracted for the determination of glucose, lactate, free glucose, glycogen, total proteins, total lipids, arginine phosphate, and arginine. As expected, lactate levels were restored more rapidly in P. defossus than in P. brasiliensis. P. defossus restored its glycogen reserves of the hepatopancreas and muscle tissue. Free glucose was quickly restored in all tissues of both species. In relation to arginine phosphate reserves, P. defossus showed a greater ability to restore this metabolite in the hepatopancreas. Both species recovered their arginine phosphate reserves, but they also used this metabolite in longer periods of recovery. Mainly in P. brasiliensis the reserves of total lipids seem to be an important source of energy during the recovery period. The animals developed various metabolic strategies to post-hypoxia recovery, mainly P. defossus which restored its reserves more completely and more rapidly than did P. brasiliensis.