Differential effects of central administration of relaxin‐3 on food intake and hypothalamic neuropeptides in male and female rats

Relaxin‐3 (RLN3) is an orexigenic neuropeptide that produces sex‐specific effects on food intake by stronger stimulation of feeding in female compared with male rats. This study determined which hypothalamic nuclei and associated neuropeptides may be involved in the sex‐specific orexigenic effects of RLN3. Relaxin‐3 (800 pmol) or vehicle was injected into the lateral ventricle of female and male rats. Food and water intake were measured after the first injection, and rats were euthanized after the second injection to determine the mRNA expression of the hypothalamic neuropeptides. Food but not water intake showed sex‐specific effects of RLN3. Stimulation of food intake by RLN3 was significantly higher in female than in male rats. No effect of RLN3 injection was found on c‐fos mRNA expression in the arcuate, dorsomedial and ventromedial hypothalamic nuclei. Increased c‐fos mRNA expression was observed in the paraventricular hypothalamic nucleus (PVN) in both sexes and in the lateral hypothalamic area (LHA) in female rats. Relaxin‐3 injections led to a sex‐nonspecific increase in the expression of oxytocin mRNA in the magnocellular PVN. Conversely, RLN3‐induced expression of anorexigenic neuropeptide arginine vasopressin (AVP) was significantly higher in the parvocellular PVN in male compared with female rats. Finally, RLN3 administration significantly increased the expression of orexin (ORX) mRNA in the LHA in female but not in male rats. Stronger expression of anorexigenic AVP in the PVN in male rats and increased expression of ORX in the LHA in female rats may contribute to stronger orexigenic effects of RLN3 in female rats compared with male rats.     

Rapid ascorbate response to bacterial elicitor treatment in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> cells

An early event of the incompatible plant–pathogen interactions is an oxidative burst. On one hand, the ROS generated during oxidative burst is advantageous. ROS can serve as secondary messengers mediating defence gene activation and establishment of additional defences. On the other hand, the concentration of ROS must be carefully regulated to avoid undesired cellular cytotoxicity. The major water soluble, low molecular weight antioxidant, ascorbic acid plays a crucial role in ROS balancing (scavenging). The regulation of ascorbate level, therefore, can be an important point of the fine-tuning of ROS level during the early phase of plant–pathogen interaction. To evaluate how this interaction affects the biosynthesis, the recycling, and the level of ascorbate, we challenged Arabidopsis thaliana cells with two different harpin proteins (HrpZ_pto and HrpW_pto). HrpZ_pto and HrpW_pto treatments caused a well-defined ROS peak. The expression of the alternative oxidase (AOX1a) and vtc5, one of the paralog genes that encode the rate limiting enzyme of ascorbate biosynthesis, followed the elevation of ROS. Similarly, the activity of ascorbate peroxidase and galactono-1,4-lactone dehydrogenase (EC 1.3.2.3) (GLDH), the enzyme catalysing the ultimate, mitochondria coupled step of ascorbate biosynthesis and the level of ascorbate and glutathione also followed the elevation of ROS due to harpin treatment. The enhanced expression of AOX1a, the elevated activity of GLDH, and the increased level of ascorbate and glutathione all can contribute to the mitigation or absence of programmed cell death. Finally, a new function, the fine-tuning of redox balance during plant–pathogen interaction, can be proposed to vtc5.     

Localization of caveolin-1 and c-src in mature and differentiating photoreceptors: raft proteins co-distribute with rhodopsin during development

Numerous biochemical and morphological studies have provided insight into the distribution pattern of caveolin-1 and the presence of membrane rafts in the vertebrate retina. To date however, studies have not addressed the localization profile of raft specific proteins during development. Therefore the purpose of our studies was to follow the localization pattern of caveolin-1, phospho-caveolin-1 and c-src in the developing retina and compare it to that observed in adults. Specific antibodies were used to visualize the distribution of caveolin-1, c-src, a kinase phosphorylating caveolin-1, and phospho-caveolin-1. The labeling pattern of this scaffolded complex was compared to those of rhodopsin and rhodopsin kinase. Samples were analyzed at various time points during postnatal development and compared to adult retinas. The immunocytochemical studies were complemented with immunoblots and immunoprecipitation studies. In the mature retina caveolin-1 and c-src localized mainly to the cell body and IS of photoreceptors, with only very weakly labeled OS. In contrast, phospho-caveolin-1 was only detectable in the OS of photoreceptors. During development we followed the expression and distribution profile of these proteins in a temporal sequence with special attention to the period when OS formation is most robust. Double labeling immunocytochemistry and immunoprecipitation showed rhodopsin to colocalize and co-immunoprecipitate with caveolin-1 and c-src. Individual punctate structures between the outer limiting membrane and the outer plexiform layer were seen at P10 to be labeled by both rhodopsin and caveolin-1 as well as by rhodopsin and c-src, respectively. These studies suggest that membrane raft specific proteins are co-distributed during development, thereby pointing to a role for such complexes in OS formation. In addition, the presence of small punctate structures containing caveolin-1, c-src and rhodopsin raise the possibility that these proteins may transport together to OS during development and that caveolin-1 exists predominantly in a phosphorylated form in the OS.     

Recognition motifs rather than phylogenetic origin influence the ability of targeting peptides to import nuclear-encoded recombinant proteins into rice mitochondria

Mitochondria fulfil essential functions in respiration and metabolism as well as regulating stress responses and apoptosis. Most native mitochondrial proteins are encoded by nuclear genes and are imported into mitochondria via one of several receptors that recognize N-terminal signal peptides. The targeting of recombinant proteins to mitochondria therefore requires the presence of an appropriate N-terminal peptide, but little is known about mitochondrial import in monocotyledonous plants such as rice (Oryza sativa). To gain insight into this phenomenon, we targeted nuclear-encoded enhanced green fluorescent protein (eGFP) to rice mitochondria using six mitochondrial pre-sequences with diverse phylogenetic origins, and investigated their effectiveness by immunoblot analysis as well as confocal and electron microscopy. We found that the ATPA and COX4 (Saccharomyces cerevisiae), SU9 (Neurospora crassa), pFA (Arabidopsis thaliana) and OsSCSb (Oryza sativa) peptides successfully directed most of the eGFP to the mitochondria, whereas the MTS2 peptide (Nicotiana plumbaginifolia) showed little or no evidence of targeting ability even though it is a native plant sequence. Our data therefore indicate that the presence of particular recognition motifs may be required for mitochondrial targeting, whereas the phylogenetic origin of the pre-sequences probably does not play a key role in the success of mitochondrial targeting in dedifferentiated rice callus and plants.

     

EcXyl43 β-xylosidase: molecular modeling,activity on natural and artificial substrates,and synergism with endoxylanases for lignocellulose deconstruction

Applied Microbiology and Biotechnology - Biomass hydrolysis constitutes a bottleneck for the biotransformation of lignocellulosic residues into bioethanol and high-value products. The efficient...     

Na‐Ion Batteries for Large Scale Applications: A Review on Anode Materials and Solid Electrolyte Interphase Formation

The urgent need for optimizing the available energy through smart grids and efficient large‐scale energy storage systems is pushing the construction and deployment of Li‐ion batteries in the MW range which, in the long term, are expected to hit the GW dimension while demanding over 1000 ton of positive active material per system. This amount of Li‐based material is equivalent to almost 1% of current Li consumption and can strongly influence the evolution of the lithium supply and cost. Given this uncertainty, it becomes mandatory to develop an energy storage technology that depends on almost infinite and widespread resources: Na‐ion batteries are the best technology for large‐scale applications. With small working cells in the market that cannot compete in cost ($/W h) with commercial Li‐ion batteries, the consolidation of Na‐ion batteries mainly depends on increasing their energy density and stability, the negative electrodes being at the heart of these two requirements. Promising Na‐based negative electrodes for large‐scale battery applications are reviewed, along with the study of the solid electrolyte interphase formed in the anode surface, which is at the origin of most of the stability problems.     

Identification of cross‐reactive B‐cell epitopes between Bos d 9.0101(Bos Taurus) and Gly m 5.0101 (Glycine max) by epitope mapping MALDI‐TOF MS

Exposure to cow's milk constitutes one of the most common causes of food allergy. In addition, exposure to soy proteins has become relevant in a restricted proportion of milk allergic pediatric patients treated with soy formulae as a dairy substitute, because of the cross‐allergenicity described between soy and milk proteins. We have previously identified several cross‐reactive allergens between milk and soy that may explain this intolerance. The purpose of the present work was to identify epitopes in the purified αS1‐casein and the recombinant soy allergen Gly m 5.0101 (Gly m 5) using an α‐casein‐specific monoclonal antibody (1D5 mAb) through two different approaches for epitope mapping, to understand cross‐reactivity between milk and soy. The 1D5 mAb was immobilized onto magnetic beads, incubated with the peptide mixture previously obtained by enzymatic digestion of the allergens, and the captured peptides were identified by MALDI‐TOF MS analysis. On a second approach, the peptide mixture was resolved by RP‐HPLC and immunodominant peptides were identified by dot blot with the mAb. Finally, recognized peptides were sequenced by MALDI‐TOF MS. This novel MS based approach led us to identify and characterize four peptides on α‐casein and three peptides on Gly m 5 with a common core motif. Information obtained from these cross‐reactive epitopes allows us to gain valuable insight into the molecular mechanisms of cross‐reactivity, to further develop new and more effective vaccines for food allergy.     

Synthesis and in vitro antitumor effect of vinblastine derivative-oligoarginine conjugates

Vinblastine is a widely used anticancer drug with undesired side effects. Its conjugation with carrier molecules could be an efficient strategy to reduce these side effects. Besides this, the conjugate could exhibit increased efficiency against resistant cells, e.g., due to the altered internalization pathway. Oligoarginines, as cell-penetrating peptides, can transport covalently attached compounds into different kinds of cells and enhance the efficiency of those compounds. We report here the coupling of vinblastine through its carboxyl group at position 16 with the N-terminal amino function of L-Trp methyl ester. After hydrolysis of the ester group, 17-desacetylvinblastineTrp was conjugated to the N-terminal amino group of oligoarginine via the C-terminal carboxyl group of the Trp moiety in solution. The antitumor effect of conjugates was studied on sensitive and resistant human leukemia (HL-60) cells in vitro. Our data suggest that all conjugates investigated possess an antiproliferative effect against the studied cells. However, the effect was dependent on the number of Arg residues in the conjugates: Arg? > Arg? ? Arg?. The conjugate with Arg? exhibited similar efficicacy as compared with free 17-desacetylvinblastineTrp. The in vitro studies also showed that the tubulin binding ability of vinblastine was essentially preserved even in the octaarginine conjugate. We also observed that two isomers were formed during conjugation. These isomers showed different levels of activity against tubulin polymerization in vitro and in vivo. The 17-desacetylvinblastineTrp-Arg?-1 isomer conjugate possessed high selectivity against the mitotic spindles. HRMS and NMR data suggest that 17-desacetylvinblastineTrp-Arg?-1 and 17-desacetylvinblastineTrp-Arg?-2 are epimers at the tryptophan α carbon atom.     

Intraspecific genome size variation and morphological differentiation of Ranunculus parnassifolius (Ranunculaceae), an Alpine–Pyrenean–Cantabrian polyploid group

The aim of this study was to assess genome size variation and multivariate morphometric analyses to ascertain cytotype distribution patterns and the morphological differentiation within the Ranunculus parnassifolius group in the Pyrenees and the Alps. Although divergences in nuclear DNA content among different species within a genus are widely acknowledged, intraspecific variation is still a somewhat controversial issue. Holoploid and monoploid genome sizes (C‐ and Cx‐values) were determined using propidium iodide flow cytometry in 125 plants of R. parnassifolius s.l. distributed across four European countries. Three different DNA ploidy levels were revealed in the study area: diploid (2n ～ 2x, 57.14%), triploid (2n ～ 3x, 1.19%), and tetraploid (2n ～ 4x, 41.67%). The mean population 2C‐values ranged from 8.15 pg in diploids to 14.80 pg in tetraploids, representing a ratio of 1 : 1.8. Marked intraspecific/interpopulation differences in nuclear DNA content were found. Diploid populations prevail in the Pyrenees, although tetraploid cytotypes were reported throughout the distribution area. In general, mixed‐cytotype populations were not found. The Spearman correlation coefficient did not reveal significant correlations between genome size and altitude, longitude, or latitude. Morphometric analyses and cluster analyses based on genome size variation revealed the presence of three major groups, which exhibited a particular biogeographical pattern. A new cytotype, DNA triploid, was found for the first time. Tetraploid populations showed constant nuclear DNA levels, whereas diploid populations from the Pyrenees, in which introgressive hybridization is suggested as a presumable trigger for genome size variation, did not. Scenarios for the evolution of geographical parthenogenesis in R. parnassifolius s.l. are discussed. Finally, the different levels of effectiveness between plant and animal reference standards are analysed. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 251–271.