Metallothionein is a crucial protective factor against Helicobacter pylori-induced gastric erosive lesions in a mouse model

Infection with the gastric pathogen Helicobacter pylori (H. pylori) causes chronic gastritis, peptic ulcer, and gastric adenocarcinoma. These diseases are associated with production of reactive oxygen species (ROS) from infiltrated macrophages and neutrophiles in inflammatory sites. Metallothionein (MT) is a low-molecular-weight, cysteine-rich protein that can act not only as a metal-binding protein, but also as a ROS scavenger. In the present study, we examined the role of MT in the protection against H. pylori-induced gastric injury using MT-null mice. Female MT-null and wild-type mice were challenged with H. pylori SS1 strain, and then histological changes were evaluated with the updated Sydney grading system at 17 and 21 wk after challenge. Although the colonization efficiency of H. pylori was essentially the same for MT-null and wild-type mice, the scores of activity of inflammatory cells were significantly higher in MT-null mice than in wild-type mice at 17 wk after challenge. Histopathological examination revealed erosive lesions accompanied by infiltration of inflammatory cells in the infected MT-null mice but not in wild-type mice. Furthermore, activation of NF-kappaB and expression of NF-kappaB-mediated chemokines such as macrophage inflammatory protein-1alpha and monocytes chemoattractant protein-1 in gastric cells were markedly higher in MT-null mice than in wild-type mice. These results suggest that MT in the gastric mucosa might play an important role in the protection against H. pylori-induced gastric ulceration.     

Involvement of fission yeast Clr6-HDAC in regulation of the checkpoint kinase Cds1

Modification of the N-terminal tail of histones is required for various nuclear processes. Here, we show that fission yeast Clr6-HDAC (histone deacetylase) regulates the checkpoint kinase Cds1 when DNA replication encounters a stressful condition. We found that the global level of acetylation of histone H4 was constant throughout the normal cell cycle, but was reduced significantly when the cell recovered from the HU-induced cell cycle arrest (or slow DNA replication). We identified the Clr6-HDAC as a component responsible for the reduction in the level of the H4 acetylation. Although DNA replication was completed, the HU-induced cell cycle arrest could not be released even after removal of HU in the clr6-1 mutant. Under this experimental condition, Cds1 kinase was maintained active and remained bound tightly to chromatin. We also demonstrated that Cds1 was active even after treatment with caffeine, an inhibitor for ATM/ATR that is an activator of Cds1. These results indicate that inactivation of Cds1 requires functional Clr6-HDAC independently of the conventional DNA replication checkpoint. When DNA replication is impeded, Clr6-HDAC activity may monitor damage on chromatin structure/environment, which is required for inactivation of Cds1.     

Effects of increased ambient temperature on the development of in vitro derived bovine zygotes

In this study, presumptive bovine zygotes were subjected to two consecutive 24-h cycles of heat treatment during the first 48 h (Experiment I) of in vitro culture (IVC) or 24h of heat treatment during the fourth day of IVC (Experiment II). In Experiment I, the percentage of heat treatment zygotes that developed to > or =8-cell stage embryos after 72 h IVC was 2.0% (n = 459) compared with 28.4% (n = 458) for the control zygotes (P<0.001). The subsequent yield of morulae or blastocysts after 144 h IVC for the heat treatment and control groups was 0.9% (n = 457) and 12.3% (n = 456) (P<0.001), respectively. These results demonstrate that heat treatment during the first 48 h of IVC significantly impaired embryo development. In Experiment II, the percentage of zygotes that developed into morulae and blastocysts following heat treatment during the fourth day of IVC was 4.5% (n = 468) compared to 10.5% (n = 456) for the control group (P<0.001). This study has demonstrated that in vitro heat stress during the critical stage of early embryo development significantly increases the incidence of early embryonic mortality.     

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.