Geographical variation in the early regeneration process of Siebold's Beech (Fagus crenata BLUME) in Japan

The causes and timing of seed death in early regeneration process of Siebold's beech (Fagus crenata Blume) was studied at 15 sites along a snowfall gradient in Japan, in order to clarify why the seedling density of the species has geographic difference remarkably. Seed production did not significantly differ along the snowfall gradient. Pre-dispersal seed mortality by insect damage was higher at sites with light snowfall than at sites with heavy snowfall, but this only seemed to be a minor factor influencing the population. A large proportion of the viable nuts that fall in autumn ware killed in winter before germination. Winter mortality was much higher at sites with thin snow cover than that at sites with thick snow cover, and this factor was strongly correlated with the geographic variation of seedling regeneration probability. There was little seed mortality by winter desiccation. The main factor contributing to the geographic difference seemed to be a seed predation by rodents in winter. Deep snow cover may reduce the success of rodents finding seeds in winter. Thus the observed relationship between snowpack depth and early mortality may be due to an indirect effect through the process of seed predation.p>     

XIAP, a cellular member of the inhibitor of apoptosis protein family, links the receptors to TAB1-TAK1 in the BMP signaling pathway.

Signals elicited by transforming growth factor-beta (TGF-beta) superfamily ligands are generated following the formation of heteromeric receptor complexes consisting of type I and type II receptors. TAK1, a member of the MAP kinase kinase kinase family, and its activator, TAB1, participate in the bone morphogenetic protein (BMP) signaling pathway involved in mesoderm induction and patterning in early Xenopus embryos. However, the events leading from receptor activation to TAK1 activation remain to be identified. A yeast interaction screen was used to search for proteins that function in the pathway linking the receptors and TAB1-TAK1. The human X-chromosome-linked inhibitor of apoptosis protein (XIAP) was isolated as a TAB1-binding protein. XIAP associated not only with TAB1 but also with the BMP receptors in mammalian cells. Injection of XIAP mRNA into dorsal blastomeres enhanced the ventralization of Xenopus embryos in a TAB1-TAK1-dependent manner. Furthermore, a truncated form of XIAP lacking the TAB1-binding domain partially blocked the expression of ventral mesodermal marker genes induced by a constitutively active BMP type I receptor. These results suggest that XIAP participates in the BMP signaling pathway as a positive regulator linking the BMP receptors and TAB1-TAK1.     

Human IgM monoclonal antibody to ganglioside GM2 and complement suppress virus propagation in ex vivo cultures of lymphocytes from HIV-1 infected patients.

HIV-1 infection induces aberrant ganglioside GM2 expression on infected cell lines, and human IgM anti-GM2 monoclonal antibody (L55 Ab) together with normal fresh human serum (FHS) as a source of complement causes complement mediated cytolysis of HIV-1 infected cells as well as HIV-1 particles. We report here that high expression of GM2 was also detected on HIV-1 infected lymphocytes from HIV-1 seropositive patients. L55 Ab effectively suppressed the generation of HIV in the presence of FHS in primarily cultured lymphocytes from HIV-1 infected patients in ex vivo experiments, and the suppression was enhanced additively by AZT. These data suggest that L55 Ab may increase the therapeutic effect of chemotherapy.     

A bioluminescent enzyme immunoassay for prostaglandin E2 using Cypridina luciferase

Prostaglandin E₂ is one of the major cyclooxygenase metabolites of arachidonic acid. We developed a competitive immunosorbent assay for prostaglandin E₂ utilizing a bioluminescent enzyme Cypridina luciferase. The prostaglandin E₂ amount could be quantified over the concentration ranging from 7.8 to 500 pg/mL. The amount of unlabeled prostaglandin E₂ required to displace 50% of the maximal binding of Cypridina luciferase‐labeled prostaglandin E₂ (B/B₀) was approximately 35 pg/mL. The results show a great potential of Cypridina luciferase as a new labeling enzyme for enzyme‐linked immunosorbent assay. Copyright © 2009 John Wiley & Sons, Ltd.     

Physiological significance of apoptosis in animal virus infection

In contrast to insect viruses, animal viruses can produce considerable amounts of progeny virus in cells undergoing apoptosis. Nevertheless, viruses in general have acquired the ability to escape apoptosis of infected cells. These facts indicate that the role of apoptosis in virus infection is different in insect virus and animal virus, although both viruses need to avoid apoptosis of the infected cells for a viral life cycle in nature. In animal virus infection, the primary role of apoptosis is considered not to be a premature lysis of the infected cells (and the following abortion of virus multiplication) but to allow the dying cells to be phagocytosed by macrophages. This phagocytosis is able to prevent dysregulated inflammatory reactions at the site of virus infection and to initiate a specific immune response against the infected virus.     

SOD1 (copper/zinc superoxide dismutase) deficiency drives amyloid β protein oligomerization and memory loss in mouse model of Alzheimer disease

Oxidative stress is closely linked to the pathogenesis of neurodegeneration. Soluble amyloid β (Aβ) oligomers cause cognitive impairment and synaptic dysfunction in Alzheimer disease (AD). However, the relationship between oligomers, oxidative stress, and their localization during disease progression is uncertain. Our previous study demonstrated that mice deficient in cytoplasmic copper/zinc superoxide dismutase (CuZn-SOD, SOD1) have features of drusen formation, a hallmark of age-related macular degeneration (Imamura, Y., Noda, S., Hashizume, K., Shinoda, K., Yamaguchi, M., Uchiyama, S., Shimizu, T., Mizushima, Y., Shirasawa, T., and Tsubota, K. (2006) Proc. Natl. Acad. Sci. U.S.A. 103, 11282-11287). Amyloid assembly has been implicated as a common mechanism of plaque and drusen formation. Here, we show that Sod1 deficiency in an amyloid precursor protein-overexpressing mouse model (AD mouse, Tg2576) accelerated Aβ oligomerization and memory impairment as compared with control AD mouse and that these phenomena were basically mediated by oxidative damage. The increased plaque and neuronal inflammation were accompanied by the generation of N(ε)-carboxymethyl lysine in advanced glycation end products, a rapid marker of oxidative damage, induced by Sod1 gene-dependent reduction. The Sod1 deletion also caused Tau phosphorylation and the lower levels of synaptophysin. Furthermore, the levels of SOD1 were significantly decreased in human AD patients rather than non-AD age-matched individuals, but mitochondrial SOD (Mn-SOD, SOD2) and extracellular SOD (CuZn-SOD, SOD3) were not. These findings suggest that cytoplasmic superoxide radical plays a critical role in the pathogenesis of AD. Activation of Sod1 may be a therapeutic strategy for the inhibition of AD progression.     

Cloning of a novel collagenase gene from the gram-negative bacterium Grimontia (Vibrio) hollisae 1706B and its efficient expression in Brevibacillus choshinensis

The collagenase gene was cloned from Grimontia (Vibrio) hollisae 1706B, and its complete nucleotide sequence was determined. Nucleotide sequencing showed that the open reading frame was 2,301 bp in length and encoded an 84-kDa protein of 767 amino acid residues. The deduced amino acid sequence contains a putative signal sequence and a zinc metalloprotease consensus sequence, the HEXXH motif. G. hollisae collagenase showed 60 and 59% amino acid sequence identities to Vibrio parahaemolyticus and Vibrio alginolyticus collagenase, respectively. In contrast, this enzyme showed < 20% sequence identity with Clostridium histolyticum collagenase. When the recombinant mature collagenase, which consisted of 680 amino acids with a calculated molecular mass of 74 kDa, was produced by the Brevibacillus expression system, a major gelatinolytic protein band of ~ 60 kDa was determined by zymographic analysis. This result suggested that cloned collagenase might undergo processing after secretion. Moreover, the purified recombinant enzyme was shown to possess a specific activity of 5,314 U/mg, an ~ 4-fold greater activity than that of C. histolyticum collagenase.     

Characterization of two forms of base non-specific and adenylic acid preferential ribonuclease from Aspergillus saitoi

Two forms of RNases (RNase ML and RNase MM) from Aspergillus saitoi which are base non-specific and adenylic acid preferential were separated from each other by DEAE-cellulose column chromatography. They are indistinguishable with respect to enzymatic properties such as base preferability, pH optimum, kinetic constants measured with 2',3'-cUMP and 2',3'-cCMP as substrates, and effects of ionic strength, physical properties such as heat stability, isoelectric point and circular dichroism spectra, amino acid composition and immunological property. They only differ in carbohydrate content. The apparent molecular weight determined by SDS-disc electrophoresis was 36,000 for RNase ML and 32,000 for RNase MM. Both RNases were reduced and carboxymethylated, and then digested with trypsin, separately. Glycopeptides were isolated from the both digests by gelfiltration and paper chromatography. The amino acid compositions of glycopeptides obtained from RNase ML (ML TS-IIC) and that obtained from RNase MM (MM TS-IIIC) were the same. The amino acid sequences of both glycopeptides determined by Edman degradation and carboxypeptidase digestion were also the same. The results indicated that RNase ML and RNase MM were the same protein having different sizes of carbohydrate chains at one site on the molecule.