Comparative ultrastructure of Mycobacterium leprae and Mycobacterium lepraemurium cell envelopes.

The structural properties of the cell envelopes of Mycobacterium leprae and Mycobacterium lepraemurium were investigated by freeze-fracture, freeze-etching, and negative-staining techniques. Freeze-fracture split the cell wall and exposed the internal features of the peptidoglycolipid mycosidic filamentous network. The cell membrane was also split into two asymmetric faces. The external fracture face was characterized by linear arrays of intramembranous particles, whereas the protoplasmic fracture face showed randomly distributed clusters of particulate entities. Comparative analysis of the ultrastructural features observed in M. leprae and M. lepraemurium indicated that the organization of the cell envelope in these two species differed particularly with respect to the amount and complexity of the superficial peptidoglycolipid and mycosidic integument, which is poorly developed in the mycobacterium responsible for human disease.     

Etude comparee des proprietes physico-chimiques des mannanes de neuf levures

In order to correlate and compare the antigenic relationships observed between nine yeast strains, we have studied their major antigenic determinant represented by the mannans. This material is a constituent of their cell.The compounds that we have isolated are, in reality, glycopeptides. All their polysaccharide fractions consist of mannose only — except for those of the compounds that we have isolated of R. glutinis and C. lipolytica. All these polysaccharides have very close ramified structures; the only one that seems to be very different is that of R. glutinis, and this is in agreement with the antigenic properties of that yeast.The peptidic fractions of these glycopeptides are rich in threonine, serine and aspartic acid and it is very likely that these amino acids make the link with the polysaccharide fraction. The quantity of these amino acids seem to be affected by the conditions of culture of the yeasts, but not their presence or absence.     

ZAKβ antagonizes and ameliorates the cardiac hypertrophic and apoptotic effects induced by ZAKα

ZAK (sterile alpha motif and leucine zipper containing kinase AZK), a serine/threonine kinase with multiple biochemical functions, has been associated with various cell processes, including cell proliferation, cell differentiation, and cardiac hypertrophy. In our previous reports, we found that the activation of ZAKα signaling was critical for cardiac hypertrophy. In this study, we show that the expression of ZAKα activated apoptosis through both a FAS‐dependent pathway and a mitochondria‐dependent pathway by subsequently inducing caspase‐3. ZAKβ, an isoform of ZAKα, is dramatically expressed during cardiac hypertrophy and apoptosis. The interaction between ZAKα and ZAKβ was demonstrated here using immunoprecipitation. The results show that ZAKβ has the ability to diminish the expression level of ZAKα. These findings reveal an inherent regulatory role of ZAKβ to antagonize ZAKα and to subsequently downregulate the cardiac hypertrophy and apoptosis induced by ZAKα.     

A three-step method for isolating a few to several hundred milligrams of protein

An operationally simple general protein isolation method was devised from three previously available separation tools, and was tested by application to two demanding fractionation problems and for yield. One test system was the isolation by gel electrofocusing of two model proteins with pI values of 4.6 and 4.8, bovine serum albumin and ovalbumin, with a load of 220 mg each. The other test was the isolation of 10 mg of human growth hormone isohormone B from a mixture of closely migrating other isohormones. The three-step procedure comprises of: (1) separation into zones of homogeneous protein by gel electrofocusing; (2) excision of the zones of homogeneous protein from the gel followed by concentration of the protein to a small volume of solution by means of Steady-State Stacking; (3) purification from polyacrylamide-like contaminants and non-volatile buffers by gel filtration followed by lyophilization. The average overall recovery was 70--80%.     

Global phylogeny of Hadrosauridae (Dinosauria: Ornithopoda) using parsimony and Bayesian methods

The late Cretaceous hadrosaurids were the most specialized and diverse clade of ornithopod dinosaurs. Parsimony and Bayesian methods were implemented to elucidate the phylogenetic relationships of all hadrosaurid species. Traditional and geometric morphometrics were applied to discover patterns of variation containing phylogenetic information. In total, 286 phylogenetically informative characters (196 cranial and 90 postcranial) were defined and documented: the most extensive character data set ever constructed for hadrosaurid dinosaurs. Of these, 136 characters were used for the first time in phylogenetic analysis of these ornithopods, and 93 were modified from those of other authors. Parsimony and the Bayesian analysis (using the Mk model without the gamma parameter) confirmed the split of hadrosaurids into Saurolophinae and Lambeosaurinae. Saurolophines included a major clade composed of the Prosaurolophus–Saurolophus and the Kritosaurus–Gryposaurus–Secernosaurus subclades. Edmontosaurus and Shantungosaurus were recovered outside the major clade of saurolophines. The Brachylophosaurus clade was recovered as the most basal clade of saurolophines in the parsimony analysis, whereas following the Bayesian analysis it was recovered as the sister clade to the Kritosaurus–Gryposaurus–Secernosaurus clade. These two analyses resulted in a Lambeosaurinae composed of a succession of Eurasian sister taxa to two major clades: the Parasaurolophus clade and the Hypacrosaurs altispinus–Corythosaurus clade. In contrast, the Bayesian analysis using the Mk model with the gamma parameter included, resulted in an unbalanced hadrosauroid tree, with a paraphyletic Saurolophinae, and with the Prosaurolophus clade, Edmontosaurus, and Shantungosaurus as successively closer sister taxa to Lambeosaurinae. Based on the strict reduced consensus tree derived from the parsimony analysis, Hadrosauridae was redefined as the clade stemming from the most recent common ancestor of Hadrosaurus foulkii and Parasaurolophus walkeri. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 435–502.     

Hydrogen sulfide:A novel component in Arabidopsis peroxisomes which triggers catalase inhibition

Plant peroxisomes have the capacity to generate different reactive oxygen and nitrogen species(ROS and RNS),such as H_2O_2,superoxide radical(O_2~-),nitric oxide and peroxynitrite(ONOO~-).These organelles have an active nitrooxidative metabolism which can be exacerbated by adverse stress conditions.Hydrogen sulfide(H_2S)is a new signaling gasotransmitter which can mediate the posttranslational modification(PTM)persulfidation.We used Arabidopsis thaliana transgenic seedlings expressing cyan fluorescent protein(CFP)fused to a canonical peroxisome targeting signal 1(PTS1)to visualize peroxisomes in living cells,as well as a specific fluorescent probe which showed that peroxisomes contain H_2S.H_2S was also detected in chloroplasts under glyphosate-induced oxidative stress conditions.Peroxisomal enzyme activities,including catalase,photorespiratory H_2O_2-generating glycolate oxidase(GOX)and hydroxypyruvate reductase(HPR),were assayed in vitro with a H_2S donor.In line with the persulfidation of this enzyme,catalase activity declined significantly in the presence of the H_2S donor.To corroborate the inhibitory effect of H_2S on catalase activity,we also assayed pure catalase from bovine liver and pepper fruit-enriched samples,in which catalase activity was inhibited.Taken together,these data provide evidence of the presence of H_2S in plant peroxisomes which appears to regulate catalase activity and,consequently,the peroxisomal H_2O_2 metabolism.