Ecological studies on the community of drifting seaweeds in the south-eastern coastal waters of Izu Peninsula, central Japan. I: Seasonal changes of plants in species composition, appearance, number of species and size

Seasonal patterns of drifting seaweeds in the southeastern coastal waters of Izu Peninsula of central Japan were examined by sampling 966 patches from spring to autumn 1991–1993. In total, 57 plant species appeared, including 10 epiphytic algal species. Monthly totals of the number of species, excluding epiphytic aigae, were highest in May (33) and August (27), though 19–21 species of sargassaceous algae were found from May to August, The number of species, excluding epiphytic algae, in one patch of drifting seaweeds was 1 to 11 (x?= 2.93 ± 2.06) with high richness in May a result of almost entirely sargassaceous species. The wet weight of each patch and maximum stipe length of plants varied from 5 to 6970 g and from 20 to 840 cm (x?= 536.1 ± 782,3 g and 110.6 ± 76.8 cm), respectively, with highs in April and May. Out of 18 species common to all years, 10 species dominated the top or second rank in monthly pooled frequency of appearance. Seasonal changes of these 10 major species were examined, Sargassum horneri (Turner) C. Agardh and Hizikia fusiformis (Harvey) Okamura were abundant in April, but were replaced partly by Sargassum muticum (Yendo) Fensholt in May and largely by Sargassum yamamotoi Yoshida in June. In July, Sargassum nipponicum Yendo and Sargassum piluliferum (Turner) C. Agardh dominated. Subsequently, the major species shifted to Sargassum ringgoldianum Harvey and S. yamamotoi in August, Sargassum micracanthum (Kützing) Endlicher, Sargassum macrocarpum C. Agardh and Zostera marina Linnaeus in September, and S. ringgoldianum and S. micracanthum in October. However, the occurrence of S. yamamotoi, S. nipponicum and S. piluliferum in June or July were particularly heterogeneous compared with other areas of Japan. Dendrogram analysis was done based on frequency of appearance. Pooled monthly samples were divided into three groups characterized from the dominant species, degree of domination, weight, length and number of species of drifting seaweeds as well as the degree of diversity or evenness in appearance. This characterization indicated that the diversity and abundance of drifting seaweeds were higher from April to June than in later months.     

Synthesis of benzamide derivatives as TRPV1 antagonists

From hit compounds identified by high throughput screening (HTS), we have found compound 1 as a lead TRPV1 antagonist and confirmed its potential as a treatment for pain. Compound 1 has led to potent TRPV1 antagonistic benzamide derivatives ((+/-)-2: human IC(50)=23 nM, (+/-)-3: human IC(50)=14 nM in the capsaicin-induced calcium influx assay) containing indole and naphthyl moieties, obtained by elaboration of the tryptamine scaffold or via bioisosteric replacements.     

Usefulness of repeated GenomiPhi, a phi29 DNA polymerase-based rolling circle amplification kit, for generation of large amounts of plasmid DNA

The GenomiPhi DNA Amplification Kit employs rolling circle amplification (RCA) using phi29 polymerase, dNTPs, and random hexamers. We demonstrated that repeated RCA (at least three times) is useful for high-fidelity amplification of large amounts of plasmid DNA.     

Intracellular Redistribution of Truncated La Protein Produced by Poliovirus 3Cpro-Mediated Cleavage

The La autoantigen (also known as SS-B), a cellular RNA binding protein, may shuttle between the nucleus and cytoplasm, but it is mainly located in the nucleus. La protein is redistributed to the cytoplasm after poliovirus infection. An in vitro translation study demonstrated that La protein stimulated the internal initiation of poliovirus translation. In the present study, a part of the La protein was shown to be cleaved in poliovirus-infected HeLa cells, and this cleavage appeared to be mediated by poliovirus-specific protease 3C (3C^pro). Truncated La protein (dl-La) was produced in vitro from recombinant La protein by cleavage with purified 3C^pro at only one Gln₃₅₈-Gly₃₅₉ peptide bond in the 408-amino-acid (aa) sequence of La protein. The dl-La expressed in L cells was detected in the cytoplasm. However, green fluorescence protein linked to the C-terminal 50-aa sequence of La protein was localized in the nucleus, suggesting that this C-terminal region contributes to the steady-state nuclear localization of the intact La protein in uninfected cells. The dl-La retained the enhancing activity of translation initiation driven by poliovirus RNA in rabbit reticulocyte lysates. These results suggest that La protein is cleaved by 3C^pro in the course of poliovirus infection and that the dl-La is redistributed to the cytoplasm. dl-La, as well as La protein, may play a role in stimulating the internal initiation of poliovirus translation in the cytoplasm.     

Preventive Effect of Betaine Against Cognitive Impairments in Amyloid β Peptide-Injected Mice Through Sirtuin1 in Hippocampus

In the pathophysiology of Alzheimer’s disease, the deposition of amyloid β peptide (Aβ) is associated with oxidative stress, leading to cognitive impairment and neurodegeneration. We have already reported that betaine (glycine betaine), an osmolyte and methyl donor in cells, prevents the development of cognitive impairment in mice with intracerebroventricular injection of Aβ_25–35, an active fragment of Aβ, associated with oxidative stress in the hippocampus, but molecular mechanisms of betaine remain to be determined. Here, to investigate a key molecule underlying the preventive effect of betaine against cognitive impairments in Aβ_25–35-injected mice, cognitive tests and qPCR assays were performed in Aβ_25–35-injected mice with continuous betaine intake, in which intake was started a day before Aβ_25–35 injection, and then continued for 8 days. The Aβ_25–35 injection impaired short-term and object recognition memories in the Y-maze and object recognition tests, respectively. PCR assays revealed the down-regulation of Sirtuin1 (SIRT1), a NAD⁺-dependent deacetylase that mediates metabolic responses, in the hippocampus of Aβ_25–35-injected mice, whereas betaine intake prevented memory deficits as well as the decrease of hippocampal SIRT1 expression in Aβ_25–35-injected mice. Further, sirtinol, an inhibitor of the Sirtuin family, blocked the preventive effect of betaine against memory deficits. On the other hand, resveratrol, the potent compound that activates SIRT1, also prevented memory impairments in Aβ_25–35-injected mice, suggesting that SIRT1 plays a causative role in the preventive effect of betaine against memory deficits caused by Aβ exposure.

     

Gangliosides are essential in the protection of inflammation and neurodegeneration via maintenance of lipid rafts: elucidation by a series of ganglioside-deficient mutant mice

Gangliosides are considered to be involved in the maintenance and repair of nervous tissues. Recently, novel roles of gangliosides in the regulation of complement system were reported by us. In this study, we compared complement activation, inflammatory reaction and disruption of glycolipid-enriched microdomain (GEM)/rafts among various mutant mice of ganglioside synthases, i.e. GM2/GD2 synthase knockout (KO), GD3 synthase KO, double KO (DKO) of these two enzymes and wild type. Up-regulation of complement-related genes, deposits of C1q, proliferation of astrocytes and infiltration of microglia also showed similar gradual severity depending on the defects in ganglioside compositions. In the expression of inflammatory cytokines such as IL-1β and tumor necrosis factor α, only DKO showed definite up-regulation. Immunoblotting of fractions from sucrose density gradient ultracentrifugation revealed that lipid raft markers such as caveolin-1 and flotillin-1 tended to disperse from the raft fractions with intensities of DKO > GM2/GD2 synthase KO > GD3 synthase KO > wild type. Decay-accelerating factor and neural cell adhesion molecule tended to disappear from the raft fraction. Phospholipids and cholesterol also tended to decrease in GEM/rafts in GM2/GD2 synthase KO and DKO, although total amounts were almost equivalent. These results indicate that destruction of GEM/rafts is caused by ganglioside deficiency with gradual intensity depending on the degree of defects of their compositions.