From the hydrolysate of siomycin A, an antibiotic from Streptomyces sioyaensis, L-threonine, L-alanine, L-valine, r>~cysteine and three thiazole-4carboxylic acid derivatives were isolated. These thiazoles were identified as thiostreptine, 2-aminomethylthiazole-4-carboxylic acid and 2-(l-amino acetonyl) thiazole-4-carboxylic acid. A 4-(<#-hydroxyethyl)-8-hydroxyquinaldic acid, and two unidentified C10-and C12-compounds were also isolated in the hydrolysate. The formation of pyruvic acid (2 moles), a-amino-w-butyric acid (less than 1 mole), propionic acid (2~3 moles) and acetaldehyde (1 mole) by the action of acid or alkali on siomycin A was demonstrated. Siomycins A, B and C, sulfur-containing peptide antibiotics, have been isolated from cultures of Streptomyces sioyaensis and siomycin preparations1*^. Characterization of the three siomycins has been described previously2). Among these antibiotics,

No abstract

In a ciliate Paramecium, the presence of water channels on the membrane of contractile vacuole has long been predicted by both morphological and physiological data, however, to date either the biochemical or the molecular biological data have not been provided. In the present study, to examine the presence of aquaporin in Paramecium, we carried out RT-PCR with degenerated primers designed based on the ParameciumDB, and an aquaporin cDNA (aquaporin 1, aqp1) with a full-length ORF encoding 251 amino acids was obtained from Paramecium multimicronucleatum by using RACE. The deduced amino acid sequence of AQP1 had NPA-NPG motifs, and the prediction of protein secondary structure by CNR5000 and hydropathy plot showed the presence of six putative transmembrane domains and five connecting loops. Phylogenetic analysis results showed that the amino acid sequence of AQP1 was close to that of the Super-aquaporin group. The AQP1-GFP fusion protein clearly demonstrated the subcellular localization of AQP1 on the contractile vacuole complex, except for the decorated spongiome membrane. The functional analyses of aqp1 were done by RNA interference-based gene silencing, using an established feeding method. The aqp1 was found to be crucial for the total fluid output of the cell, the function of contractile vacuole membranes.

No abstract

No abstract