Mitochondria‐type GPAT is required for mitochondrial fusion

Glycerol‐3‐phosphate acyltransferase (GPAT) is involved in the first step in glycerolipid synthesis and is localized in both the endoplasmic reticulum (ER) and mitochondria. To clarify the functional differences between ER‐GPAT and mitochondrial (Mt)‐GPAT, we generated both GPAT mutants in C. elegans and demonstrated that Mt‐GPAT is essential for mitochondrial fusion. Mutation of Mt‐GPAT caused excessive mitochondrial fragmentation. The defect was rescued by injection of lysophosphatidic acid (LPA), a direct product of GPAT, and by inhibition of LPA acyltransferase, both of which lead to accumulation of LPA in the cells. Mitochondrial fragmentation in Mt‐GPAT mutants was also rescued by inhibition of mitochondrial fission protein DRP‐1 and by overexpression of mitochondrial fusion protein FZO‐1/mitofusin, suggesting that the fusion/fission balance is affected by Mt‐GPAT depletion. Mitochondrial fragmentation was also observed in Mt‐GPAT‐depleted HeLa cells. A mitochondrial fusion assay using HeLa cells revealed that Mt‐GPAT depletion impaired mitochondrial fusion process. We postulate from these results that LPA produced by Mt‐GPAT functions not only as a precursor for glycerolipid synthesis but also as an essential factor of mitochondrial fusion.     

Dye coupling and connexin expression by cortical radial glia in the early postnatal subventricular zone

In this study, we have analyzed the specific contribution of the cortical radial glia (RG) for gap junctional communication (GJC) within the postnatal subventricular zone (SVZ). To specifically target RG as source of dye‐coupling in situ, we have developed a new technique that involves direct cell loading through the processes that reach the pial surface, with a mix of gap junction permeant (Lucifer yellow, LY) and nonpermeant (rhodamine‐conjugated dextran 3 KDa, RD) fluorochromes, the latter used as a marker for direct loaded cells. Tissue sections were analyzed for identification of directly loaded (LY+RD+) and coupled cells (LY+RD–) in the SVZ. Directly loaded cells were restricted to the region underlying the pial loading surface area. Coupled cells were distributed in a bistratified manner, along the outer dorsal surface of the SVZ and aligning the ventricle, leaving the SVZ core relatively free. Blocking GJC prior to pial loading greatly reduced dye coupling. Phenotypic analysis indicated that coupling by RG excludes neuroblasts and is mostly restricted to cells of glial lineage. Notwithstanding, no corresponding restriction to specific cell phenotype was found for two connexin isotypes, Cx43 and Cx45, in the postnatal SVZ. The extensive homocellular cell coupling by RG suggests an important role in the regulation of neurogenesis and functional compartmentalization of the postnatal SVZ. © 2012 Wiley Periodicals, Inc. Develop Neurobiol 2012     

Ameliorative effects of resveratrol on liver injury in streptozotocin‐induced diabetic rats

The objective of this study was to investigate the ameliorative property and potential mechanism of resveratrol (RVT) in a dose of 10 mg/kg for 15 consecutive days against liver injury in streptozotocin‐induced diabetic rats. Diabetic rats significantly (P < 0.05) exhibited liver injury manifested by increased aspartylaminotransferase, alanine aminotransferase, and bilirubin; disturbed liver weight to body weight; and confirmed by hematoxylin and eosin staining. Liver from diabetic rats exhibited significant increase in malondialdehyde level and significant decrease in reduced glutathione, glutathione‐S‐transferase, quinone reductase, catalase, and superoxide dismutase. Diabetic rats showed significant disturbance in serum lipid profile. Treatment with RVT significantly (P < 0.05) abrogated diabetes‐induced perturbation in these parameters and liver histology. These data suggest that RVT treatment is associated with promising hepatoprotective effect against diabetes‐induced liver damage via reduction of serum glucose level and oxidative damage and improving serum lipid profile. © 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:384–392, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21432     

Revealing phosphoproteins playing role in tobacco pollen activated in vitro

The transition between the quiescent mature and the metabolically active germinating pollen grain most probably involves changes in protein phosphorylation status, since phosphorylation has been implicated in the regulation of many cellular processes. Given that, only a minor proportion of cellular proteins are phosphorylated at any one time, and that phosphorylated and nonphosphorylated forms of many proteins can co‐exist within a cell, the identification of phosphoproteins requires some prior enrichment from a crude protein extract. Here, we have used metal oxide/hydroxide affinity chromatography (MOAC) based on an aluminum hydroxide matrix for this purpose, and have generated a population of phosphoprotein candidates from both mature and in vitro activated tobacco pollen grains. Both electrophoretic and nonelectrophoretic methods, allied to MS, were applied to these extracts to identify a set of 139 phosphoprotein candidates. In vitro phosphorylation was also used to validate the spectrum of phosphoprotein candidates obtained by the MOAC phosphoprotein enrichment. Since only one phosphorylation site was detected by the above approach, titanium dioxide phosphopeptide enrichment of trypsinized mature pollen crude extract was performed as well. It resulted in a detection of additional 51 phosphorylation sites giving a total of 52 identified phosphosites in this set of 139 phosphoprotein candidates.     

Role of intraguild predation in aphidophagous guilds

The concept of intraguild predation (IGP) appeared in 1987–1989 to describe trophic interactions within a guild of arthropods inhabiting a sand dune desert: consumers B prey on consumers A and both of them prey on a common resource. Theory predicts that the two types of consumers should only coexist if consumer A is more efficient in the conversion of the common resource than B. As a consequence, this resource is more abundant in the presence than in the absence of intraguild predators. Such a theoretical prediction probably explains the vivid interest shown by ecologists involved in biological control for IGP. It is therefore not surprising that many papers report on IGP among natural enemies of aphids. A close examination of these reported cases indicates that they rarely fulfil the theoretical requirements for IGP. That is, guilds of aphidophagous insects are rarely the theatre of IGP but frequently of interspecific predation. This is confirmed by experimental assessment of the cost of attacking and eating intraguild prey instead of extraguild in ladybird beetles.     

Banana defence responses to Cosmopolites sordidus feeding and methyl jasmonate application

Each year 25–75% of banana and plantain yields are lost because of rhizome damages caused by banana weevil (Cosmopolites sordidus) in growing regions of sub‐Saharan Africa. However, the specific plant defence response of the rhizome tissue in relation to the C. sordidus attack is unknown. Consequently, in this study, we evaluated whether plant defence substances in the rhizome are correlated with the degree of larval damage and whether applications of methyl jasmonate (MJ) elicit a greater induction of the plant defence potential against C. sordidus. Moreover, we attempted to reveal cellular modifications in response to the root feeding herbivore through histochemical staining. The banana cultivars “Km5” and “Mbwazirume” with tolerance and susceptibility to C. sordidus, respectively, were used in a pot experiment to evaluate percent rhizome damage, leaf chlorophyll content, total phenolic content (TPC), antioxidant capacity and cell morphology in response to C. sordidus attack and/or MJ applications compared to untreated control plants. We found that C. sordidus‐induced rhizome damage was 30% in the susceptible cultivar but less than 5% in the tolerant cultivar. The percent rhizome damage was not related to leaf chlorophyll content but showed a significant negative linear relationship to both TPC and antioxidant capacity. Larvae feeding induced a considerably greater increase of polyphenolic defence compounds in Km5 than in Mbwazirume; however, this response was opposite in the MJ treatment, suggesting that the phytohormone induced the susceptible plant to invest more into the synthesis of defence chemicals that in turn lead to reduced C. sordidus damage. Tissue staining demonstrated a greater deposition of lignin and suberin in C. sordidus challenged rhizome, presumably to seal off healthy tissue with a physical barrier from continued pest attack. It is concluded that MJ induces polyphenolics in susceptible Mbwazirume banana that reduced C. sordidus damage.     

Genetic Predisposition and its Heredity in the Context of Increased Prevalence of Dermatophytoses

Mycopathologia - Dermatophytosis is a widespread disease with high prevalence and a substantial economic burden associated with costs of treatment. The pattern of this infectious disease covers a...