Two new species of Torymus Dalman, 1820 (Hymenoptera: Torymidae) parasitizing Celticecis japonica Yukawa and Tsuda, 1987 (Diptera: Cecidomyiidae) that induce leaf galls on Celtis species (Ulmaceae) in Japan

Torymus celticolus Matsuo sp. nov. and Torymus celtidigalla Matsuo sp. nov. (Hymenoptera: Torymidae) are described as parasitoids of larvae of Celticecis japonica Yukawa & Tsuda, 1987 (Diptera: Cecidomyiidae) that induce leaf galls on Celtis species (Ulmaceae) in Japan. A key to species of the genus Torymus known in Japan is provided.     

Enantioselective ester hydrolase from Sphingobacterium sp. 238C5 useful for chiral resolution of β-phenylalanine and for its β-peptide synthesis

A novel enzyme, β-phenylalanine ester hydrolase, useful for chiral resolution of β-phenylalanine and for its β-peptide synthesis was characterized. The enzyme purified from the cell free-extract of Sphingobacterium sp. 238C5 well hydrolyzed β-phenylalanine esters (S)-stereospecifically. Besides β-phenylalanine esters, the enzyme catalyzed the hydrolysis of several α-amino acid esters with l-stereospecificity, while the deduced 369 amino acid sequence of the enzyme exhibited homology to alkaline d-stereospecific peptide hydrolases from Bacillus strains. Escherichia coli transformant expressing the β-phenylalanine ester hydrolase gene exhibited an about 8-fold increase in specific (S)-β-phenylalanine ethyl ester hydrolysis as compared with that of Sphingobacterium sp. 238C5. The E. coli transformant showed (S)-enantiomer specific esterase activity in the reaction with a low concentration (30 mM) of β-phenylalanine ethyl ester, while it showed both esterase and transpeptidase activity in the reaction with a high concentration (170 mM) of β-phenylalanine ethyl ester and produced β-phenylalanyl-β-phenylalanine ethyl ester. This transpeptidase activity was useful for β-phenylalanine β-peptide synthesis.     

Universal partitioning of the hierarchical fold network of 50-residue segments in proteins

Background  

Several studies have demonstrated that protein fold space is structured hierarchically and that power-law statistics are satisfied in relation between the numbers of protein families and protein folds (or superfamilies). We examined the internal structure and statistics in the fold space of 50 amino-acid residue segments taken from various protein folds. We used inter-residue contact patterns to measure the tertiary structural similarity among segments. Using this similarity measure, the segments were classified into a number (K _c) of clusters. We examined various K _c values for the clustering. The special resolution to differentiate the segment tertiary structures increases with increasing K _c. Furthermore, we constructed networks by linking structurally similar clusters.     

Real-time monitoring of RNA helicase activity using fluorescence resonance energy transfer in vitro

We have developed a continuous fluorescence assay based on fluorescence resonance energy transfer (FRET) for the monitoring of RNA helicase activity in vitro. The assay is tested using the hepatitis C virus (HCV) NS3 helicase as a model. We prepared a double-stranded RNA (dsRNA) substrate with a 5′ fluorophore-labeled strand hybridized to a 3′ quencher-labeled strand. When the dsRNA is unwound by helicase, the fluorescence of the fluorophore is emitted following the separation of the strands. Unlike in conventional gel-based assays, this new assay eliminates the complex and time-consuming steps, and can be used to simply measure the real-time kinetics in a single helicase reaction. Our results demonstrate that Alexa Fluor 488 and BHQ1 are an effective fluorophore-quencher pair, and this assay is suitable for the quantitative measurement of the RNA helicase activity of HCV NS3. Moreover, we found that several extracts of marine organisms exhibited different inhibitory effects on the RNA and DNA helicase activities of HCV NS3. We propose that this assay will be useful for monitoring the detailed kinetics of RNA unwinding mechanisms and screening RNA helicase inhibitors at high throughput.     

Infection of less virulent Helicobacter pylori strains in asymptomatic healthy individuals in Thailand as a potential contributing factor to the Asian enigma

In Thailand, gastric cancer incidence is considerably low despite the high prevalence of Helicobacter pylori infection. We investigated the prevalence of H. pylori infection and the genotypes of cagA by using 179 stool specimens obtained from asymptomatic Thai individuals. In this study, the prevalence of H. pylori infection was 43.6%, and the detection rate of cagA-positive strains was 43.5%. In addition, the proportion of the highly virulent East-Asian type of cagA was 7.2%. These results indicate that the low prevalence of cagA-positive H. pylori strain as well as the low prevalence of East-Asian genotype cagA-positive strains may contribute to the low gastric cancer incidence.     

Molecular phylogenies of figs and fig-pollinating wasps in the Ryukyu and Bonin (Ogasawara) islands, Japan

The interaction between figs (Ficus, Moraceae) and fig-pollinating wasps (Chalcidoidea, Agaonidae) is one of the most specific mutualisms, and thus is a model system for studying coevolution and cospeciation. In this study we focused on figs and their associated fig-wasps found in the Ryukyu and Bonin (Ogasawara) Islands, Japan, because it has been suggested that breakdown in the specificity may occur in islands or at edge of a species' distribution. We collected 136 samples of 15 native fig species and 95 samples of 13 associated fig-wasps from all major islands in the Ryukyu Islands, including two fig species and one fig-wasp species endemic to the Bonin Islands. We performed molecular phylogenetic analyses using plastid DNA and nuclear ITS sequences for the figs and nuclear 28S rRNA and mitochondrial COI genes for the fig-wasps to investigate the interspecific phylogenies and intraspecific variation within the mutualism. Our phylogenetic analyses using multiple samples per species show the single clade of each fig (except the Bonin endemic species) and fig-pollinating wasp species. Fig species belonging to the same subgenera formed well-supported clades in both plastid and ITS trees, except for the subgenus Urostigma. Likewise, fig wasps emerging from host fig species belonging to the same subgenera formed mostly well supported clades in both 28S and COI trees. Host specificity between the figs and fig-wasps functions strictly in these islands. There was very little sequence variation within species, and that no major geographic structure was found. The two Bonin endemic species (F. boninsimae and F. nishimurae) or their common ancestor and the associated fig-wasps (Blastophaga sp.) are apparently derived from F. erecta and its associated fig-wasps (B. nipponica), respectively, and probably migrated from the Ryukyu Islands.     

Enhanced target-specific accumulation of radiolabeled antibodies by conjugating arginine-rich peptides as anchoring molecules

We have devised and estimated a new strategy to prolong the residence time of radiolabeled antibodies in tumor in which an octaarginine peptide (R?) was used as an anchoring molecule to fix antibodies against CD20 (NuB2; IgG2a) on tumor cells. Conjugation of R? with antibodies was performed by maleimide-thiol chemistry using thiol groups generated by reducing the disulfide bonds of the antibody. The R?-conjugated NuB2 was then reacted with succinimidyl meta-[12?I]iodobenzoate to prepare [12?I]SIB-NuB2(I) (0.92 R?/NuB2) and [12?I]SIB-NuB2(III) (3.38 R?/NuB2). Both SIB-NuB2(I) and SIB-NuB2(III) exhibited size-exclusion HPLC elution profiles and immunoreactivity to CD20-positive cells similar to those of NuB2. NuB2(I) also possessed isoelectric focusing (IEF) profile similar to NuB2. However, NuB2(III) registered a broad IEF band toward higher pI. When incubated with CD20-positive cells, [12?I]SIB-NuB2(I) and [12?I]SIB-NuB2(III) exhibited 1.4 and 4.0 times higher cell-associated radioactivity than [12?I]SIB-NuB2. After the cells were washed and reincubated in a fresh medium for 3 h, [12?I]SIB-NuB2(I) and [12?I]SIB-NuB2(III) exhibited significantly higher cell-associated radioactivity than [12?I]SIB-NuB2. In biodistribution studies in normal mice, while both [12?I]SIB-NuB2(I) and [12?I]SIB-NuB2 exhibited similar biodistribution profiles, [12?I]SIB-NuB2(III) showed faster clearance from the blood and higher hepatic radioactivity levels than [12?I]SIB-NuB2. In SCID mice bearing CD20-positive xenografts, [131I]SIB-NuB2(I) exhibited significantly higher radioactivity in xenografts than those of [12?I]SIB-NuB2 with no significant increase being observed in other tissues. The findings indicate that appropriate R? modification of antibodies satisfies both specific targeting ability of antibody and strong cell-association property of R?, which was reflected in the increased radioactivity levels in tumor. These findings supported the applicability of this approach to enhance target-specific accumulation of radiolabeled antibodies.     

Age-dependent increase of magnesium in the cerebral arteries of Thai

To elucidate compositional changes of the cerebral arteries with aging, the authors investigated age-related changes of elements in the cerebral arteries by inductively coupled plasma-atomic emission spectrometry (ICP-AES). After an ordinary dissection by medical students at Chiang Mai University was finished, the anterior, middle, and posterior cerebral arteries and the anterior and posterior communicating arteries were resected from the subjects. The subjects consisted of six men and seven women, ranging in age from 34 to 86 yr. The element content was determined by ICP-AES. It was found that the Mg content increased progressively with aging in all of the anterior, middle, and posterior cerebral arteries, but the Ca and P content did not increase significantly with aging in the anterior, middle, and posterior cerebral arteries, with the one exception being that the P content increased significantly in the posterior cerebral arteries with aging. The average content of Ca was higher in the order of the anterior communicating, anterior cerebral, posterior communicating, posterior cerebral, and middle cerebral arteries.     

Endogenous alphaCGRP protects against concanavalin A-induced hepatitis in mice

To evaluate hepatoprotective effect of alpha-calcitonin gene-related peptide (alphaCGRP), we compared the susceptibilities of alphaCGRP-/- and wild-type mice to concanavalin A (Con A)-induced hepatitis. Twelve hours after Con A administration, serum transaminases were markedly higher in alphaCGRP-/- than wild-type mice, and much more extensive TUNEL-positive lesions and DNA fragmentation were detected in the livers of alphaCGRP-/- mice. Notably, expression of IL-6 was selectively diminished in alphaCGRP-/- mice, suggesting that induction of IL-6 during acute inflammatory responses is blunted in alphaCGRP-/- mice. In addition, primary cultured alphaCGRP-/- hepatocytes were more susceptible to IFN-gamma-induced cell death than hepatocytes from wild-type mice. Administration of exogenous alphaCGRP reduced the incidence of apoptosis among hepatocytes and endothelial cells. It thus appears that alphaCGRP exerts a hepatoprotective effect by modulating cytokine expression and preventing apoptosis.