Microtubular structures in a stable staphylococcal L-form.

Microtubular structures, which were demonstrated as straight, dense-walled cylinders attached to cell membranes, were found in a stable staphylococcal L-form grown in the absence of antibiotic.     

Modes of DNA replication primed with the oligomer of palindrome

What is the precise molecular mechanism of semi-conservative DNA replication? After the great efforts of the past 20 years, molecular biology has now established the discontinuous syntheses of daughter DNA on both of the parental strands. In order to explain this type of discontinuous replication, we introduce the concept of a palindromic primer.First we focus our attention on various oligomers (RNA or DNA) which appear usually or occasionally in the process of replication. Then we propose the palindromic nature of these oligomers so as to serve as the primer of DNA synthesis. This postulation gives a theoretical reasoning for the discontinuities of both new strands in the fork region of replication.Subsequently we consider Watson's concatemeric intermediate theory, proposed for the explanation of replicative synthesis of phage T7 DNA. By considering the contribution of some sequence-specific endonuclease(s), we suggest the existence of partial palindromic sequences of bases at the connecting region(s) in which the redundant ends of the respective phage DNA molecules are overlapping. Another theory on the replication of linear chromosomal DNA including the concept of the terminal palindromic sequence of bases is also analyzed from the viewpoint of palindromic primer. Further, some recent experimental approaches, especially on the origin(s) of DNA replication, are shown to favour the concept of a palindromic primer.     

Rat cathepsin H-catalyzed transacylation: comparisons of the mechanism and the specificity with papain-superfamily proteases.

We found that rat cathepsin H showed strong transacylation activity under physiological conditions. It is a feature of cathepsin H to utilize amino acid amides not only as acyl-acceptors but also as acyl-donors in the reaction. The pH-dependence of the transacylation activity was distinct from those of other papain-superfamily proteases. The alkaline limb (pKapp = 7.5) could be regarded as the pKa of the alpha-amino group of the acyl-donor, which was also involved in the original amino-peptidase activity. The acidic limb (pKapp = 5.8) was suggested to be involved in the deacylation step, where amino acid amide attacked the acyl-intermediate as a nucleophile in place of water in the hydrolysis. Although the N alpha-deprotonated acyl-acceptor, which is supposed to govern the nucleophilic attack, has a small population in the acidic pH range (above pH5), the transacylation was detectable even at the acidic pH-range because of the high S1'-site binding ability and suitable nucleophilicity of the acyl-acceptor. In the transacylation between various amino acid amides, the S1 and S1' site appeared to prefer hydrophobic residues without and regardless of a branch at beta-carbon, respectively. From these results and the sequence homology in the papain superfamily, we concluded that the reaction was governed by the acyl-donor having a protonated amino group, the acyl-acceptor having a deprotonated amino group and the remarkable hydrophobic character (especially favoring tryptophan amide) of the S1' site, presumably reflecting the good conservation of Trp177 in papain-superfamily proteases.     

Ethanol production from starch in a pervaporation membrane bioreactor using Clostridium thermohydrosulfuricum

To attain both high productivity and efficient recovery of ethanol from broth, a membrane bioreactor consisting of a jar fermentor and a pervaporation system was applied to the direct production of ethanol from uncooked starch with a thermophilic anaerobic bacterium, Clostridium thermohydrosulfuricum. From four types of ethanol-selective membranes tested, microporous polytetrafluoroethylene (PTFE) membrane, the pores of which are impregnated with silicone rubber, was chosen for its large flux, high ethanol selectivity, and high stability. During fed-batch fermentation with pervaporation in the membrane bioreactor, ethanol was continuously extracted and concentrated in two traps with concentrations at 5.6%-6.2% (w/w) in trap 1 (20 degrees C) and 27%-32% (w/w) in trap 2 (liquid N(2)), while the ethanol concentration in the broth was maintained at 0.85-0.9% (w/w). Due to the low ethanol concentration in the broth, and the immobilization of bacterial cells by the membrane, the number of viable cells, and, eventually, the ethanol productivity, increased in the membrane bioreactor.     

Anti-platelet aggregating and disaggregating activities of 6,9-methano PGI2

Anti-platelet aggregating and disaggregating activities of the chemically stable 6,9-methano prostaglandin I₂ (6,9-methano PGI₂) were investigated. 6,9-Methano PGI₂ inhibited ADP-induced platelet aggregation in PRP from humans, rabbits and rats. 6,9-Methano PGI₂ also inhibited rabbit platelet aggregation induced by ADP, collagen, thrombin, arachidonic acid and 11,9-epoxy-methano PGH₂. Antiaggregating activities of 6,9-methano PGI₂ were 0.3 to 2.0 times greater than those of PGE₁. 6,9-Methano PGI₂ facilitated platelet disaggregation in a dose related manner. Antiaggregating and disaggregating activities of 6,9-methano PGI₂ were markedly enhanced by incubation with the phosphodiesterase inhibitor, theophylline.     

New species and combinations in neotropical Lecythidaceae

Lecythis barnebyi Mori andCorythophora amapaensis Pires ex Mori & Prance are described and the following new combinations are coined:Lecythis brancoensis (R. Knuth) Mori,L. schwackei (R. Knuth) Mori,L. alutacea (A. C. Smith) Mori,L. lurida (Miers)Mori, L. holcogyne (Sandwith)Mori, L. corrugata Poiteau subsp.rosea (Spruce ex Berg) Mori, andCorythophora labriculata (Eyma) Mori & Prance.