Lactate has the potential to promote hydrogen sulphide formation in the human colon

High concentrations of sulphide are toxic for the gut epithelium and may contribute to bowel disease. Lactate is a favoured cosubstrate for the sulphate-reducing colonic bacterium Desulfovibrio piger , as shown here by the stimulation of sulphide formation by D. piger DSM749 by lactate in the presence of sulphate. Sulphide formation by D. piger was also stimulated in cocultures with the lactate-producing bacterium Bifidobacterium adolescentis L2-32. Other lactate-utilizing bacteria such as the butyrate-producing species Eubacterium hallii and Anaerostipes caccae are, however, expected to be in competition with the sulphate-reducing bacteria (SRB) for the lactate formed in the human colon. Strains of E. hallii and A. caccae produced 65% and 96% less butyrate from lactate, respectively, in a coculture with D. piger DSM749 than in a pure culture. In triculture experiments involving B. adolescentis L2-32, up to 50% inhibition of butyrate formation by E. hallii and A. caccae was observed in the presence of D. piger DSM749. On the other hand, sulphide formation by D. piger was unaffected by E. hallii or A. caccae in these cocultures and tricultures. These experiments strongly suggest that lactate can stimulate sulphide formation by SRB present in the colon, with possible consequences for conditions such as colitis.     

Mating tests in Agrocybe cylindracea sensu lato. Recognition of Agrocybe wrightii as a novel species

Mating compatibility tests among seven collections of A. cylindracea (Basidiomycetes, Agaricales) from distant geographic origins were carried out with the aim of determining if A. cylindracea includes one or more taxons from a biological perspective. Fruit body production was used to obtain spore prints, monosporic cultures and to evaluate the fructification potential of compatible crossings. Protoplast isolation, purification and regeneration were used to attempt obtaining monokaryotic isolates from 2-spored specimens. Mating tests evidenced inter-fertility of Asian, American and European strains and the inter-sterility of the Argentinean strain WT-54. These results, in addition to mitochondrial small subunit variable domains phylogeny and morphological data, lead us to consider this strain as a novel species, A. wrightii. The European, Asian and the rest of the American strains belong to A. cylindracea. The concept of A. cylindracea sensu lato includes at least two different species: A. cylindracea and A. wrightii.     

Chromosomal localization of the human and mouse histidine decarboxylase genes by in situ hybridization. Exclusion of the HDC gene from the Prader-Willi syndrome region

Using a rat histidine decarboxylase (HDC) cDNA probe, we have mapped the HDC gene by in situ hybridization to the ql5–q2l region of human chromosom e15 and to the E5-G region of murine chromosome 2. These localizations strengthen a syntenic group conserved between human chromosome 15 and mouse chromosome 2. The localization of the HDC gene on the human chromosome 15 map shows that it is not included within the Prader-Willi Syndrome region (PWCR).     

Amine coupling versus biotin capture for the assessment of sulfonamide as ligands of hCA isoforms

This work was dedicated to the development of a reliable SPR method allowing the simultaneous and quick determination of the affinity and selectivity of designed sulfonamide derivatives for hCAIX and hCAXII versus hCAII, in order to provide an efficient tool to discover drugs for anticancer therapy of solid tumors. We performed for the first time a comparison of two immobilization approaches of hCA isoforms. First one relies on the use of an amine coupling strategy, using a CM7 chip to obtain higher immobilization levels than with a CM5 chip and consequently the affinity with an higher precision (CV% < 10%). The second corresponds to a capture of proteins on a streptavidin chip, named CAP chip, after optimization of biotinylation conditions (amine versus carboxyl coupling, biotin to protein ratio). Thanks to the amine coupling approach, only hCAII and hCAXII isoforms were efficiently biotinylated to reach relevant immobilization (3000 RU and 2700 RU, respectively) to perform affinity studies. For hCAIX, despite a successful biotinylation, capture on the CAP chip was a failure. Finally, concordance between affinities obtained for the three derivatives to CAs isozymes on both chips has allowed to valid the approaches for a further screening of new derivatives.     

Production Model Press for the Preparation of Bacterial Cell Walls

A modification of the apparatus previously described permits the preparation of cell walls in quantity. This consists of a heavy duty, double-acting hydraulic press with motor-driven pump, and a superstrength alloy steel pressure cell which is corrosion resistant. Liquid cooling of the jet is substituted for the previously used gas cooling to minimize aerosol formation and to facilitate subsequent treatment of the products. The device produces cell walls of excellent quality in good yield. The pressure cell has been used satisfactorily up to about 60,000 psi. Design details are given.