Adaptive changes of chloroplast membrane lipid components under environmental factors

Review deals with some modern views of the membrane chloroplast lipid composition role in low-, high temperature and water stress adaptive reactions. It is shown that the transformed changes in membrane lipid composition determined the biochemical adaptive process due homeostasis support and preservation of the lipid bilayer fluidity, being necessary for their normal functioning in the changed environmental conditions. The aspects of long-term and short-term adaptive reactions in protein/lipid membrane complexes is discussed. The lipid sensor functions at genetically regulation of adaptive mechanisms is considered.     

Outgroup sampling in phylogenetics: Severity of test and successive outgroup expansion

Outgroup sampling is a fundamental step in the design of phylogenetic analyses, independent of optimality criterion, taxonomic group, or source of evidence. Studies have demonstrated the efficient analysis of many thousands of terminals, all of which could be included in any empirical investigation, yet outgroup samples typically include only a small number of terminals. Most discussion of outgroup sampling centers on employing “correct” or “appropriate” outgroup terminals to increase “accuracy” or “reliability” by preventing “errors” such as long branch attraction and “incorrect” ingroup rooting. As an alternative, I develop a theory of outgroup sampling grounded in the logic of scientific discovery, whereby the objective is to test nested hypotheses of ingroup topology and character‐state transformation as severely as possible by incorporating outgroup terminals in unconstrained, simultaneous analysis, using background knowledge to select the terminals that have the greatest chance of refuting those hypotheses. This framework provides a logical basis for selecting outgroup taxa but does not provide grounds for limiting the outgroup sample, given that, ceteris paribus, testability and explanatory power increase with the inclusion of additional terminals. Therefore, I propose the ancillary procedure of successively expanding the outgroup sample until ingroup hypotheses become stable (insensitive) to increased sampling, with each expansion guided by the scientific objectives of outgroup sampling. This is a heuristic procedure that does not prevent more outgroup terminals from being sampled or guarantee that ingroup hypotheses will remain insensitive to further outgroup expansion, and it has no bearing on the objective support of a given hypothesis. Nevertheless, it provides an objective, empirical basis for limiting outgroup sampling in a given research cycle. I illustrate this procedure by examining the effect of successive outgroup expansion on the relationships among the poison frog genera Adelphobates, Dendrobates, and Oophaga.     

Translocation of poly(ethylene glycol-co-hexadecyl)cyanoacrylate nanoparticles into rat brain endothelial cells: role of apolipoproteins in receptor-mediated endocytosis

Previous in vivo observations in rats have shown that poly(ethylene glycol) polyhexadecylcyanoacrylate (PEG-PHDCA) nanoparticles could translocate into the brain after intravenous injection, which polyhexadecylcyanoacrylate (PHDCA) nanoparticles did not. Through the detailed analysis of the plasma protein adsorption onto the surface of PEG-PHDCA nanoparticles, the present study aimed at clarifying the mechanism by which nanoparticles could penetrate into rat brain endothelial cells (RBEC). Two-dimensional polyacrylamide gel electrophoresis and Western blotting revealed that, after incubation with rat serum, apolipoprotein E (ApoE) adsorbed more onto PEG-PHDCA than on PHDCA nanoparticles. Adsorption of apolipoprotein B-100 (ApoB-100) onto PEG-PHDCA nanoparticles was demonstrated by capillary electrophoresis experiments. Moreover, only when ApoE or ApoB-100 were preadsorbed onto PEG-PHDCA nanoparticles, nanoparticles were found to be more efficient than control nanoparticles for penetrating into RBEC, suggesting the involvement of a low density lipoprotein receptor in this process. Thus, these data clearly demonstrate the involvement of apolipoproteins in the brain transport of PEG-PHDCA nanoparticles, which may open interesting prospects for brain drug delivery.     

Influence of the characteristics of lipids on the regulation of biochemical processes in animal liver and blood

It has been established experimentally that the character and the scale of interrelations between various parameters of the phospholipid composition and their group-average values depend significantly on the characteristics of lipids (the antioxidative activity, quantity of peroxides, and antiperoxide activity) of animal liver and blood erythrocytes. It was shown that a single injection of low-toxicity Tween 80 and acetone at low doses modifies the intensity of lipid peroxidation in the liver and changes the physicochemical properties of lipids, and the interrelations between the parameters that are coordinated in norm, thereby causing the disturbance of biochemical functions of the liver.     

A chromosomal genomics approach to assess and validate the desi and kabuli draft chickpea genome assemblies

With the expansion of next‐generation sequencing technology and advanced bioinformatics, there has been a rapid growth of genome sequencing projects. However, while this technology enables the rapid and cost‐effective assembly of draft genomes, the quality of these assemblies usually falls short of gold standard genome assemblies produced using the more traditional BAC by BAC and Sanger sequencing approaches. Assembly validation is often performed by the physical anchoring of genetically mapped markers, but this is prone to errors and the resolution is usually low, especially towards centromeric regions where recombination is limited. New approaches are required to validate reference genome assemblies. The ability to isolate individual chromosomes combined with next‐generation sequencing permits the validation of genome assemblies at the chromosome level. We demonstrate this approach by the assessment of the recently published chickpea kabuli and desi genomes. While previous genetic analysis suggests that these genomes should be very similar, a comparison of their chromosome sizes and published assemblies highlights significant differences. Our chromosomal genomics analysis highlights short defined regions that appear to have been misassembled in the kabuli genome and identifies large‐scale misassembly in the draft desi genome. The integration of chromosomal genomics tools within genome sequencing projects has the potential to significantly improve the construction and validation of genome assemblies. The approach could be applied both for new genome assemblies as well as published assemblies, and complements currently applied genome assembly strategies.     

Diel pattern of migration in a poisonous toad from Brazil and the evolution of chemical defenses in diurnal amphibians

Most amphibians with biphasic life cycles have aquatic eggs and larvae and terrestrial adults that migrate between terrestrial habitats and aquatic breeding sites. Migration usually occurs at night in order to avoid desiccation and predation. However, some amphibians also migrate during the day, and it has been proposed that this may have evolved as a result of poisonous skin secretions and aposematic coloration that release individuals from visually oriented diurnal predators. Based on this hypothesis and recent observations of 24 h breeding activity in the poisonous, aposematic toad Melanophryniscus cambaraensis, we predicted that migration in this species would occur equally during the day and night. To test our prediction we documented the diel pattern of migratory activity over multiple explosive breeding events from October 2008 to February 2009 (127 nights) at a temporary stream in Rio Grande do Sul state, southern Brazil. We also obtained environmental data to determine if diel activity could be attributed to variation in rainfall, barometric pressure, temperature, and/or relative air humidity. Contrary to our prediction, migratory activity in M. cambaraensis is strongly diurnal. Although temperature and humidity varied significantly between day and night intervals, this variation does not account for the diurnal-only migratory activity of M. cambaraensis. We suggest that the diurnal-only migratory activity of M. cambaraensis is best explained by phylogeny, not contemporary functions or selective pressures. Diurnal activity is primitive for this species and evolved in the common ancestor of Agastorophrynia, prior to the chemical defenses found in toads (Bufonidae) and poison frogs (Dendrobatidae). This suggests that chemical defenses in these groups may have evolved as a result of the diurnal activity that brought them into contact with visually oriented diurnal predators, and not the other way around.     

Comment on Amézquita et al. (2017) “Conspicuousness,color resemblance,and toxicity in geographically diverging mimicry: The pan‐Amazonian frog Allobates femoralis”

Amézquita et al. (2017) recently concluded that species of the Allobates femoralis group are toxic to mice at levels equivalent to syntopic alkaloid‐containing poison frogs, which they attributed to the presence of alkaloids in skin secretions. However, the chemical composition of skin secretions was not analyzed, and here we present additional data supporting the absence of alkaloids in skin secretions of the Allobates femoralis group. Instead, we suggest the observed toxicity was caused by the anesthetic benzocaine, which was applied to the buccal cavity to euthanize frogs prior to skin removal. We show that orally administered benzocaine is rapidly incorporated into the skin of species that sequester and do not sequester alkaloids, which casts doubt on the conclusion that Allobates femoralis group skin secretions are toxic and makes the results of experiments with alkaloid‐containing species of Adelphobates and Ameerega uninterpretable. To prevent experimental errors and misinterpretations in studies of amphibian chemical defense, we encourage researchers to test the chemical composition of samples prior to experimentation, include all necessary controls to detect false positives, conduct small pilot studies for new methods, and consider the limitations of particular methods and their ability to address the intended research questions.     

Estradiol and progesterone regulate the migration of mast cells from the periphery to the uterus and induce their maturation and degranulation

Background

Mast cells (MCs) have long been suspected as important players for implantation based on the fact that their degranulation causes the release of pivotal factors, e.g., histamine, MMPs, tryptase and VEGF, which are known to be involved in the attachment and posterior invasion of the embryo into the uterus. Moreover, MC degranulation correlates with angiogenesis during pregnancy. The number of MCs in the uterus has been shown to fluctuate during menstrual cycle in human and estrus cycle in rat and mouse indicating a hormonal influence on their recruitment from the periphery to the uterus. However, the mechanisms behind MC migration to the uterus are still unknown.

Methodology/Principal Findings

We first utilized migration assays to show that MCs are able to migrate to the uterus and to the fetal-maternal interface upon up-regulation of the expression of chemokine receptors by hormonal changes. By using a model of ovariectomized animals, we provide clear evidences that also in vivo, estradiol and progesterone attract MC to the uterus and further provoke their maturation and degranulation.

Conclusion/Significance

We propose that estradiol and progesterone modulate the migration of MCs from the periphery to the uterus and their degranulation, which may prepare the uterus for implantation.