Hypoglycemic activities of MTP-3631, a novel thiopyranopyrimidine derivative.

MTP-3631 is a novel thiopyranopyrimidine derivative structurally different from any existent hypoglycemic agents. MTP-3631 markedly decreased basal blood glucose and improved glucose intolerance in genetically diabetic C57BL/6J ob/ob mice, which was not affected by tolbutamide. MTP-3631 also caused hypoglycemic effects in normal rats, but no change was observed in plasma insulin level. Unlike buformin, MTP-3631 did not change plasma lactate level in ob/ob mice. These results suggest that the hypoglycemic mechanism of MTP-3631 may be essentially different from those of sulfonylureas and biguanides.     

A first total synthesis of a novel sulfated ganglioside, 3'-O-sulfo-GM1b

A first total synthesis of a novel sulfated ganglioside, 3'-O-sulfo-GM1b, is described. The suitably protected gangliotriose (GgOSe3) derivative, 2-(trimethylsilyl)ethyl (2-acetamido-4,6-O-benzylidene-2-deoxy-beta-D-galactopyranosyl)-(1-->4)-(2,6-di-O-benzyl-3-O-p-methoxybenzyl-beta-D-galactopyranosyl)-(1-->4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside was glycosylated with the alpha-NeuAc-(2-->3)-galactose donor to give the protected GM1b oligosaccharide (95%). After proper manipulation of the protecting groups, the oligosaccharide was converted into the target ganglioside by the successive introduction of the ceramide and sulfo groups, followed by complete deprotection.     

Cloning and overexpression of the avi2 gene encoding a major cellulase produced by Humicola insolens FERM BP-5977

The avi2 gene encoding Avi2, which is a major cellulase produced by Humicola insolens FERM BP-5977, was cloned and sequenced. Avi2 showed high homology with other family 6 cellulases. The expression vector pNCE4 containing the avi2 gene was constructed, and this strain was transformed using a protoplast method. As a result, the pNCE4 transformant secreted 8-fold more Avi2 than the recipient strain.     

Ultrastructural studies on the pheromone-producing cells in the silkmoth, Bombyx mori: formation of cytoplasmic lipid droplets before adult eclosion

In Bombyx mori, pheromone-producing cells accumulate a number of lipid droplets in the cytoplasm preceding the production of the sex pheromone, bombykol. The process of lipid droplet formation in the pheromone-producing cells was investigated by using light and electron microscopy. Light microscopy revealed that the lipid droplets appeared from 2 days before adult eclosion and dramatic accumulation took place between 2 days and 1 day before eclosion. Electron microscopical studies revealed that smooth endoplasmic reticulum and numerous vesicles, their sizes being less than 1 microm, were detectable 2 days before eclosion, and some vesicles were fused with mitochondria at this stage. These characteristic changes in the pheromone-producing cells suggest that fatty acyl-CoA synthesis following de novo fatty acid synthesis takes place at this time. Involutions in the basal plasma membrane of the cells occurred throughout the observed period, which were extensive on the day before adult eclosion. Besides extensive basal involutions, immature lipid droplets appeared and then mature fully electron-dense lipid droplets were observed on the day of adult eclosion. These ultrastructural observations, combined with recent physiological studies suggest, that the basal involutions presumably reflect the uptake of lipidic components required for the construction of lipid droplets, the function of which is to store the bombykol precursor and to provide it for bombykol biosynthesis in response to pheromonotropic stimuli by pheromone biosynthesis activating neuropeptide (PBAN).     

Localized PEM mRNA and protein are involved in cleavage-plane orientation and unequal cell divisions in ascidians

BACKGROUND: Orientation and positioning of the cell division plane are essential for generation of invariant cleavage patterns and for unequal cell divisions during development. Precise control of the division plane is important for appropriate partitioning of localized factors, spatial arrangement of cells for proper intercellular interactions, and size control of daughter cells. Ascidian embryos show complex but invariant cleavage patterns mainly due to three rounds of unequal cleavage at the posterior pole. RESULTS: The ascidian embryo is an emerging model for studies of developmental and cellular processes. The maternal Posterior End Mark (PEM) mRNA is localized within the egg and embryo to the posterior region. PEM is a novel protein that has no known domain. Immunostaining showed that the protein is also present in the posterior cortex and the in centrosome-attracting body (CAB) and that the localization is extraction-resistant. Here we show that PEM of Halocynthia roretzi is required for correct orientation of early-cleavage planes and subsequent unequal cell divisions because it repeatedly pulls a centrosome toward the posterior cortex and the CAB, respectively, where PEM mRNA and protein are localized. When PEM activity is suppressed, formation of the microtubule bundle linking the centrosome and the posterior cortex did not occur. PEM possibly plays a role in anchoring microtubule ends to the cortex. In our model of orientation of the early-cleavage planes, we also amend the allocation of the conventional animal-vegetal axis in ascidian embryos, and discuss how the newly proposed A-V axis provides the rationale for various developmental events and the fate map of this animal. CONCLUSIONS: The complex cleavage pattern in ascidian embryos can be explained by a simple rule of centrosome attraction mediated by localized PEM activity. PEM is the first gene identified in ascidians that is required for multiple spindle-positioning events.     

Seasonal variability in chromophoric dissolved organic matter in the Sakawa River and Sagami Bay, Japan

We investigated the chromophoric dissolved organic matter (CDOM) of river water in the Sakawa River and of surface water in the vicinity of the river’s mouth in Sagami Bay, Japan, during the period from July 2003 to July 2004. Absorption by CDOM was modeled as a logarithmic function. As a qualitative index of CDOM, the slope (S) of this function was estimated for a wavelength range from 280 to 500 nm. As a quantitative index of CDOM, the integration of absorption was determined between 280 and 500 nm (Σ ₂₈₀ ⁵⁰⁰ a _CDOM). High seasonal variability of S values was observed at the marine station. The S values at the upstream stations were related to chlorophyll a concentrations but not to bacterial abundance, whereas the integrated values at upstream stations were correlated with precipitation. Seasonal variability in the integrated values was low at the downstream stations, where the effect of effluent from nonpoint sources and sewage treatment plants was strong. Anthropogenic CDOM at the downstream stations appeared to be degraded by microbial utilization and photodegradation, whereas terrestrially derived CDOM at the upstream stations was less degraded. These qualitative differences in CDOM and the marked effect of dilution by seawater near the Sakawa River mouth suggest that the dynamics of CDOM in riverine and coastal environments should be studied with careful consideration of both spatial and temporal variations, particularly in small estuaries.     

Ostrinia spp. in Japan: their host plants and sex pheromones

To contribute to the understanding of the genus Ostrinia (Lepidoptera; Pyralidae) in Japan, we collected larvae of Ostrinia spp. from known host plants and plants not recorded as hosts, and we examined the morphology and sex pheromones of the adults obtained. Consequently, the host plant ranges of the 7 Ostrinia spp. in Japan were clarified, and the sex pheromones of the 5 species O. scapulalis, O. zealis, O. zaguliaevi, O. palustralis and O. latipennis were identified in addition to that of the Asian corn borer O. furnacalis. The phylogenetic relationships of Japanese Ostrinia spp., with reference to the European corn borer O. nubilalis, are discussed based on these findings and results of molecular phylogenetic analyses.     

In situ egg production and hatching success of the marine copepod Pseudocalanus newmani in Funka Bay and adjacent waters off southwestern Hokkaido, Japan: associated to diatom bloom

. Clutch size and egg viability were examined for wild femalesof Pseudocalanus newmani collected from four different stationsinside and outside Funka Bay, southwestern Hokkaido, Japan,during pre-phytoplankton-bloom conditions in 1997, and froma single station outside the bay during the period from pre-to post-blooming seasons in 1998, to examine spatio-temporalvariability of the reproductive parameters and to detect deleteriouseffects of diatom blooms on in situ copepod reproduction. Clutchsize and hatching success in P.newmani were relatively similarat the four stations in 1997. The eggs almost always hatchedcompletely, but deformed nauplii occurred in 20–40% ofthe cases. The proportion of deformed nauplii gradually decreasedwhen the females were fed on non-diatom Pavlova sp. in the laboratory,suggesting that the occurrence of deformed nauplii was relatedto the quality of in situ food particles, including diatoms.Clutch size varied from 12 to 30 eggs female^–1 duringthe study period in 1998; more than 90% of the variation couldbe explained by the body size of the females which dependedon ambient water temperature. Hatching success also varied,from 15 to 80%, but was not related to either clutch size, femalebody size, water temperature or diatom biomass. These resultssuggest that not only egg production but also hatchability shouldbe measured routinely when estimating recruitment of the copepodinto the planktonic population, and show that neither clutchsize nor egg viability are directly affected by diatom biomass.Although we could not obtain clear evidence of in situ deleteriouseffects of diatoms on abnormal embryos and nauplii, this mightbe related to methodological problems and properties or characteristicsof prey–predator interactions. Also, deformities of copepodnauplii have not yet been observed for reasons other than feedingon diatoms.