Comissão Estadual da Produção Orgânica em Mato Grosso do Sul - CPOrg-MS.

bitstream/item/66239/1/31387.pd

Lipopolysaccharide from Gut-Associated Lymphoid-Tissue-Resident Alcaligenes faecalis: Complete Structure Determination and Chemical Synthesis of Its Lipid A

Alcaligenes faecalis is the predominant Gram-negative bacterium inhabiting gut-associated lymphoid tissues, Peyer's patches. We previously reported that an A. faecalis lipopolysaccharide (LPS) acted as a weak agonist for Toll-like receptor 4 (TLR4)/myeloid differentiation factor-2 (MD-2) receptor as well as a potent inducer of IgA without excessive inflammation, thus suggesting that A. faecalis LPS might be used as a safe adjuvant. In this study, we characterized the structure of both the lipooligosaccharide (LOS) and LPS from A. faecalis. We synthesized three lipid A molecules with different degrees of acylation by an efficient route involving the simultaneous introduction of 1- and 4′-phosphates. Hexaacylated A. faecalis lipid A showed moderate agonistic activity towards TLR4-mediated signaling and the ability to elicit a discrete interleukin-6 release in human cell lines and mice. It was thus found to be the active principle of the LOS/LPS and a promising vaccine adjuvant candidate

The Vitamin B1 Metabolism of Staphylococcus aureus Is Controlled at Enzymatic and Transcriptional Levels

Vitamin B1 is in its active form thiamine pyrophosphate (TPP), an essential cofactor for several key enzymes in the carbohydrate metabolism. Mammals must salvage this crucial nutrient from their diet in order to complement the deficiency of de novo synthesis. In the human pathogenic bacterium Staphylococcus aureus, two operons were identified which are involved in vitamin B1 metabolism. The first operon encodes for the thiaminase type II (TenA), 4-amino-5-hydroxymethyl-2-methylpyrimidine kinase (ThiD), 5-(2-hydroxyethyl)-4-methylthiazole kinase (ThiM) and thiamine phosphate synthase (ThiE). The second operon encodes a phosphatase, an epimerase and the thiamine pyrophosphokinase (TPK). The open reading frames of the individual operons were cloned, their corresponding proteins were recombinantly expressed and biochemically analysed. The kinetic properties of the enzymes as well as the binding of TPP to the in vitro transcribed RNA of the proposed operons suggest that the vitamin B1 homeostasis in S. aureus is strongly regulated at transcriptional as well as enzymatic levels

Noble gases in Muong Nong-type tektites and their implications

We have measured the elemental abundances and isotopic compositions of noble gases in Muong Nong-type tektites from the Australasian strewn field by crushing and by total fusion of the samples. We found that the abundances of the heavy noble gases are significantly enriched in Muong Nong-type tektites compared to those in normal splash-form tektites from the same strewn field. Neon enrichments were also observed in the Muong Nong-type tektites, but the Ne/Ar ratios were lower than those in splash-form tektites because of the higher Ar contents in the former. The absolute concentrations of the heavy noble gases in Muong Nong-type tektites are similar to those in impact glasses. The isotopic ratios of the noble gases in Muong Nong-type tektites are mostly identical to those in air, except for the presence of radiogenic 40Ar. The obtained K-Ar ages for Muong Nong-type tektites were about 0.7 Myr, similar to ages of other Australasian tektites. The crushing experiments suggest that the noble gases in the Muong Nong-type tektites reside mostly in vesicles, although Xe was largely affected by adsorbed atmosphere after crushing. We used the partial pressure of the heavy noble gases in vesicles to estimate the barometric pressure in the vesicles of the Muong Nong-type tektites. Likely, Muong Nong-type tektites solidified at the altitude (between the surface and a maximum height of 8-30 km) lower than that for splash-form tektites.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

A regulator gene for acetate utilisation from Neurospora crassa.

The Neurospora crassa homologue of the Aspergillus nidulans regulatory gene facB has been cloned. The gene encodes a putative transcriptional activator of 865 amino acids that contains a DNA-binding domain with a Zn(II)(2)Cys(6) binuclear cluster, a linker region and a leucine zipper-like heptad repeat. Two internal amino acid sequences are identical to peptide sequences determined from proteolytic fragments of a DNA-binding protein complex specific for genes involved in acetate utilisation and expressed in acetate-induced mycelia of N. crassa. Recombinant expression of the predicted DNA-binding domain demonstrates that it is capable of independent recognition of a subset of the promoter sequences that bind the protein complex from N. crassa. A duplication-induced mutation in the corresponding gene results in an acetate non-utilising phenotype that is characterised by inefficient induction of the enzymes required for acetate utilisation. The new gene does not fall into any existing complementation group and has been designated acu-15