Antiviral activities against herpes simplex virus type 1 by HPH derivatives and their structure-activity relationships

The compound named Histidine-pyridine-histidine (HPH) is an oxygen-activating ligand derived from the structure of bleomycin. We synthesized HPH derivatives, namely HPH-1 to -8, and investigated their antiviral activities against herpes simplex virus type 1. HPH-8 showed potent antiviral activity with an EC50 of 15 microM, and relatively high cytotoxicity with a CC50 of 37 microM. In contrast, HPH-4 indicated a weaker antiviral activity with an EC50 of 79 microM, but exhibited a far more less cytotoxicity (CC50 500 microM). Other HPH derivatives showed no effects against antiviral activities and cytotoxicities.     

Crystal structure-based studies of cytosolic sulfotransferase

Sulfation is a widely observed biological reaction conserved from bacterium to human that plays a key role in various biological processes such as growth, development, and defense against adversities. Deficiencies due to the lack of the ubiquitous sulfate donor 3'-phosphoadenosine-5'-phosphosulfate (PAPS) are lethal in humans. A large group of enzymes called sulfotransferases catalyze the transfer reaction of sulfuryl group of PAPS to the acceptor group of numerous biochemical and xenochemical substrates. Four X-ray crystal structures of sulfotransferases have now been determined: cytosolic estrogen, hydroxysteroid, aryl sulfotransferases, and a sulfotransferase domain of the Golgi-membrane heparan sulfate N-deacetylase/N-sulfotransferase 1. These have revealed the conserved core structure of the PAPS binding site, a common reaction mechanism, and some information concerning the substrate specificity. These crystal structures introduce a new era of the study of the sulfotransferases.     

Emergent mechanisms in multiple pattern generation of the lobster pyloric network

By using a hard-wired oscillator network, multiple pattern generation of the lobster pyloric network is simulated. The network model is constructed using a relaxation oscillator representing an oscillatory or quiescent (i.e. steady-state) neuron. Modulatory inputs to the network are hypothesized to cause changes in the dynamical properties of each pyloric neuron: the oscillatory frequency, the postinhibitory rebound property, and the resting membrane potential. Changes in each of these properties are induced by changing appropriate parameters of the oscillator. By changing seven parameters of the network as a whole, modulatory input-dependent patterns are successfully simulated. Received: 13 July 1999 / Accepted in revised form: 17 December 1999     

Effects of high amylose maize starch and Clostridium butyricum on metabolism in colonic microbiota and formation of azoxymethane-induced aberrant crypt foci in the rat colon

High amylose maize starch (HAS) is not digested in the small intestine and most of it reaches the large intestine. In the large intestine, HAS is fermented by intestinal bacteria, resulting in production of short-chain fatty acids (SCFA), particularly butyrate. Clostridium butyricum can utilize HAS and produce butyrate and acetate. It has been proposed that butyrate inhibits carcinogenesis in the colon. In this study, we examined the inhibitory effects of HAS and C. butyricum strain MIYAIRI588 (CBM588) on azoxymethane-induced aberrant crypt foci (ACF) formation in rats. In the group of rats administered only CBM588 spores, the concentration of butyrate in the cecum increased, but there was no decrease in the number of ACF. In the group of rats fed an HAS diet, a decrease in the number of ACF was observed, and in the group of rats administered HAS and CBM588, the number of ACF decreased significantly. In these two groups, the concentrations of acetate and propionate in intestinal contents significantly increased, but the concentration of butyrate did not change. It was found that the beta-glucuronidase activity level of colonic contents decreased significantly in the two groups of rats fed HAS. This study showed that HAS and CBM588 changed the metabolism of colonic microbiota and decreased the level of beta-glucuronidase activity, phenomena that may play a role in the inhibition of ACF formation in the rat colon.     

Kinetically controlled optical resolution of racemic norbornene aldehyde derivatives

A new method for obtaining optically pure 5-norbornene 2-endo-aldehyde derivatives was developed. The reaction of a diastereomeric mixture of the ene acetals 2 and 2', derived from racemic norbornene aldehydes (+/-)-1 and chiral nonracemic (S,S)-hydrobenzoin 7, with NBS (0.5-0.6 eq.) in the presence of H(2)O proceeded in a kinetically controlled manner to give the optically pure hydroxy aldehydes 3 along with the intact ene acetals 2'. Both compounds 3 and 2' were converted into the optically pure norbornene aldehydes 1 and ent-1, respectively. This method opens the way to produce various types of 5-norbornene 2-endo-aldehydes with 3-exo- or 3-endo-substituents in optically pure forms.     

Gene flow and mating system in five <Emphasis Type="Italic">Cryptomeria japonica</Emphasis> D. Don seed orchards as revealed by analysis of microsatellite markers

We investigated gene flow in five Cryptomeria japonica D. Don seed orchards of two different types (common and miniature) at widely spaced locations using microsatellite markers. The quality of a seed crop is determined by many factors, including pollen contamination from outside sources, self-fertilization, and the proportion of contributions from constituent clones. Contamination rates were found to vary among ramets both within seed orchards (10.0–76.7% in the most variable seed orchard) and among seed orchards (35.0–65.8% on average). Among ramets, there were significant negative correlations between pollen contamination rate and their distance from the orchard edge; among seed orchards, there were significant positive correlations between the pollen contamination rate and the C. japonica forest area nearby. Some proportion of the pollen (10.7% of total contamination) also migrated from parts of the orchards that had not been treated with gibberellin to induce flowering. Self-fertilization rates varied among seed orchards (1.4–4.4% on average), and there were significant positive correlations between self-fertilization rate and the number of ramets per clone in both types of seed orchard. Contributions as pollen donors differed significantly among clones in all seed orchards. The distance between planted ramets, flowering phenology, and relative pollen fecundity may also have contributed to observed differences in paternal contribution. The influence of these factors on genetic potential did not differ greatly between the two types of orchards. This work was supported by grants from the Pioneer Special Studies Program of the Japanese Ministry of Agriculture, Fishery, and Forestry; the Program for Promotion of Basic Research Activities for Innovative Biosciences; and research fellowships from the Japan Society for the Promotion of Science for Young Scientists.     

Functional reconstitution of a crenarchaeal splicing endonuclease in vitro

Sulfolobus tokodaii strain 7 is one of Crenarchaea whose entire genome has been sequenced. The genome sequence revealed that it possesses two open reading frames (ORFs) that are homologous to EndA, a protein responsible for splicing endonuclease activity in Archaea. Interestingly, one of the two ORFs lacks a putative catalytic amino acid residue for the nuclease activity. To investigate their functions, the two ORF products were individually expressed in Escherichia coli, partially purified, and tested for their nuclease activities in vitro. Using in vitro transcribed tRNA precursor as a substrate, we found that the two ORF products are concurrently required to cleave exon-intron junctions. Our finding implies that the splicing endonuclease for the organism is a multi-subunit complex composed of the two endA gene products.     

Isolation and physiochemical properties of protein-rich nematode mitochondrial ribosomes

In the present study, mitochondrial ribosomes of the nematode Ascaris suum were isolated and their physiochemical properties were compared to ribosomes of Escherichia coli. The sedimentation coefficient and buoyant density of A. suum mitochondrial ribosomes were determined. The sedimentation coefficient of the intact monosome was about 55 S. The buoyant density of formaldehyde-fixed ribosomes in cesium chloride was 1.40 g/cm(3), which suggests that the nematode mitoribosomes have a much higher protein composition than other mitoribosomes. The diffusion coefficients obtained from dynamic light scattering measurements were (1.48 +/- 0.04) x 10(-)(7) cm(2) s(-)(1) for 55 S mitoribosomes and (1.74 +/- 0.04) x 10(-)(7) cm(2) s(-)(1) for the 70 S E. coli monosome. The diameter of mitoribosomes was measured by dynamic light-scattering analysis and electron microscopy. Though the nematode mitoribosome has a larger size than the bacterial ribosome, it does not differ significantly in size from mammalian mitoribosomes.