Long term bed rest with and without vibration exercise countermeasures: effects on human muscle protein dysregulation

The present investigation, the first in the field, was aimed at analyzing differentially, on individual samples, the effects of 55 days of horizontal bed rest, a model for microgravity, on myosin heavy and myosin light chain isoforms distribution (by SDS) and on the proteome (by 2-D DIGE and MS) in the vastus lateralis (VL), a mixed type II/I (～50:50%) head of the quadriceps and in the calf soleus (SOL), a predominantly slow (～35:65%) twitch muscle. Two separate studies were performed on six subjects without (BR) and six with resistive vibration exercise (RVE) countermeasures, respectively. Both VL and SOL underwent in BR decrements of ～15% in cross-sectional area and of ～22% in maximal torque that were prevented by RVE. Myosin heavy chain distribution showed increased type I and decreased type IIA in BR both in VL and in SOL, the opposite with RVE. A substantial downregulation of proteins involved in aerobic metabolism characterized both in SOL and VL in BR. RVE reversed the pattern more in VL than in SOL, whereas proteins involved in anaerobic glycolysis were upregulated. Proteins from the Z-disk region and from costamers were differently dysregulated during bed rest (both BR and RVE), particularly in VL.     

Characterisation of source-separated household waste intended for composting

Large-scale composting of source-separated household waste has expanded in recent years in the Nordic countries. One problem can be low pH at the start of the process. Incoming biowaste at four composting plants was characterised chemically, physically and microbiologically. The pH of food waste ranged from 4.7 to 6.1 and organic acid concentration from 24 to 81 mmol kg(-1). The bacterial diversity in the waste samples was high, with all samples dominated by Gammaproteobacteria, particularly Pseudomonas and Enterobacteria (Escherichia coli, Klebsiella, Enterobacter). Lactic acid bacteria were also numerically important and are known to negatively affect the composting process because the lactic acid they produce lowers the pH, inhibiting other bacteria. The bacterial groups needed for efficient composting, i.e. Bacillales and Actinobacteria, were present in appreciable amounts. The results indicated that start-up problems in the composting process can be prevented by recycling bulk material and compost.     

Connective tissue growth factor induction by lysophosphatidic acid requires transactivation of transforming growth factor type β receptors and the JNK pathway

Transforming growth factor β (TGF-β) is a very strong pro-fibrotic factor which mediates its action, at least in part, through the expression of connective tissue growth factor (CTGF/CCN2). Along with these cytokines, the involvement of phospholipids in wound healing and the development of fibrosis has been revealed. Among them, lysophosphatidic acid (LPA) is a novel, potent regulator of wound healing and fibrosis that has diverse effects on many types of cells. We decided to evaluate the effect of LPA together with TGF-β on CTGF expression. We found that myoblasts treated with LPA and TGF-β1 produced an additive effect on CTGF expression. In the absence of TGF-β, the induction of CTGF expression by LPA was abolished by a dominant negative form of the TGF-β receptor type II (TGF-βRII) and by the use of SB 431542, a specific inhibitor of the serine/threonine kinase activity of TGF-βRI, suggesting that CTGF induction is dependent on LPA and requires active TGF-βRs. Moreover, we show that LPA requires Smad-2/3 proteins for the induction of CTGF expression, but not their phosphorylation or their nuclear translocation. The requirement of TGF-βRI for LPA mediated-effects is differential, since treatment of myoblasts with LPA in the presence of SB 431542 abolished the induction of stress fibers but not the induction of proliferation. Finally, we demonstrated that CTGF induction in response to LPA requires the activation of JNK, but not ERK, signaling pathways. The JNK requirement is independent of TGF-βRI-mediated activity. These novel results for the mechanism of action of LPA and TGF-β are important for understanding the role of pro-fibrotic growth factors and phospholipids involved in wound healing and related diseases.     

RNase Y in Bacillus subtilis: a Natively disordered protein that is the functional equivalent of RNase E from Escherichia coli

The control of mRNA stability is an important component of regulation in bacteria. Processing and degradation of mRNAs are initiated by an endonucleolytic attack, and the cleavage products are processively degraded by exoribonucleases. In many bacteria, these RNases, as well as RNA helicases and other proteins, are organized in a protein complex called the RNA degradosome. In Escherichia coli, the RNA degradosome is assembled around the essential endoribonuclease E. In Bacillus subtilis, the recently discovered essential endoribonuclease RNase Y is involved in the initiation of RNA degradation. Moreover, RNase Y interacts with other RNases, the RNA helicase CshA, and the glycolytic enzymes enolase and phosphofructokinase in a degradosome-like complex. In this work, we have studied the domain organization of RNase Y and the contribution of the domains to protein-protein interactions. We provide evidence for the physical interaction between RNase Y and the degradosome partners in vivo. We present experimental and bioinformatic data which indicate that the RNase Y contains significant regions of intrinsic disorder and discuss the possible functional implications of this finding. The localization of RNase Y in the membrane is essential both for the viability of B. subtilis and for all interactions that involve RNase Y. The results presented in this study provide novel evidence for the idea that RNase Y is the functional equivalent of RNase E, even though the two enzymes do not share any sequence similarity.     

The role of gap junction membrane channels in development

In most developmental systems, gap junction-mediated cell-cell communication (GJC) can be detected from very early stages of embryogenesis. This usually results in the entire embryo becoming linked as a syncytium. However, as development progresses, GJC becomes restricted at discrete boundaries, leading to the subdivision of the embryo into communication compartment domains. Analysis of gap junction gene expression suggests that this functional subdivision of GJC may be mediated by the differential expression of the connexin gene family. The temporal-spatial pattern of connexin gene expression during mouse embryogenesis is highly suggestive of a role for gap junctions in inductive interactions, being regionally restricted in distinct developmentally significant domains. Using reverse genetic approaches to manipulate connexin gene function, direct evidence has been obtained for the connexin 43 (Cx43) gap junction gene playing a role in mammalian development. The challenges in the future are the identification of the target cell populations and the cell signaling processes in which Cx43-mediated cell-cell interactions are critically required in mammalian development. Our preliminary observations suggest that neural crest cells may be one such cell population.     

Evidence of heterogeneous selection on quantitative traits of Prosopis flexuosa (Leguminosae) from multivariate Q ST –F ST test

Prosopis flexuosa is an arboreal Leguminosae that grows in arid and semiarid temperate zones of Argentina, in the Monte eco-region. It is a promising native forest species for recovering arid and semiarid regions because it plays an important role in erosion control as well as in soil fertility. Furthermore, it provides diverse economical resources. The main challenge to the forestry sector is finding a balance between production and forest protection. For this purpose, it is necessary to gather information about genetic parameters. In this study, we measured the distribution of the variation of 14 quantitative traits in an experimental half-sib stand, where families are representative of hierarchically structured populations. We applied a multivariate extension of the classical Q _ST –F _ST neutrality test to determine the relative importance of drift versus selection in the distribution of genetic variability. We found strong evidence that different selective regimes act on different traits and that selection favors different optima in each sampling site. The selection to different optima is much stronger among than within provenances. This result helps explain the possible causes for the regional variation observed in P. flexuosa and to define the management units and the evolutionarily significant units for this species.     

ADP-ribosylation factor/COPI-dependent events at the endoplasmic reticulum-Golgi interface are regulated by the guanine nucleotide exchange factor GBF1

ADP-ribosylation factor (ARF) mediated recruitment of COPI to membranes plays a central role in transport between the endoplasmic reticulum (ER) and the Golgi. The activation of ARFs is mediated by guanine nucleotide exchange factors (GEFs). Although several ARF-GEFs have been identified, the transport steps in which they function are still poorly understood. Here we report that GBF1, a member of the Sec7-domain family of GEFs, is responsible for the regulation of COPI-mediated events at the ER-Golgi interface. We show that GBF1 is essential for the formation, differentiation, and translocation of pre-Golgi intermediates and for the maintenance of Golgi integrity. We also show that the formation of transport-competent ER-to-Golgi intermediates proceeds in two stages: first, a COPI-independent event leads to the formation of an unstable compartment, which is rapidly reabsorbed in the absence of GBF1 activity. Second, the association of GBF1 with this compartment allows COPI recruitment and leads to its maturation into transport intermediates. The recruitment of GBF1 to this compartment is specifically inhibited by brefeldin A. Our findings imply that the continuous recruitment of GBF1 to spatially differentiated membrane domains is required for sustained membrane remodeling that underlies membrane traffic and Golgi biogenesis.     

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