Biochemical characterization of photosystem I complexes having different subunit compositions of fucoxanthin chlorophyll a/c-binding proteins in the diatom Chaetoceros gracilis

Photosynthesis Research - Diatoms are dominant phytoplankton in aquatic environments and have unique light-harvesting apparatus, fucoxanthin chlorophyll a/c-binding protein (FCP). Diatom...     

winged eye Induces Transdetermination of Drosophila Imaginal Disc by Acting in Concert with a Histone Methyltransferase,Su(var)3-9

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Sulfite suppresses the mutagenic property of coffee

The mutagenicity of instant and freshly brewed coffee on Salmonella typhimurium TA100 and TA98 without S9 mix was inactivated by sodium sulfite. Sulfite ion at a dose of 200 ppm almost completely inactivated the mutagenicity of coffee made in the ordinary way (5-15 mg dry weight/ml). Sodium bisulfite and potassium metabisulfite had similar effects. On the contrary, L-ascorbic acid enhanced the mutagenicity of coffee. Sodium sulfite also inactivated the phage-inducing activity of coffee in inductest III. Sodium sulfite completely suppressed the mutagenicities of 1,2-dicarbonyls, namely diacetyl and glyoxal. Diacetyl is present in coffee, beer, butter and other foods and drinks. Because sodium sulfite, sodium bisulfite and potassium metabisulfite are widely used as food additives, they should be useful in reducing the levels of mutagens in foods.     

Antioxidative effects of fluvastatin and its metabolites against oxidative DNA damage in mammalian cultured cells

We investigated the effects of fluvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on reactive oxygen species (ROS) and on oxidative DNA damage in vitro, as well as the effects of the main fluvastatin metabolites (M2, M3, and M4) and other inhibitors of the same enzyme, pravastatin and simvastatin. The hydroxyl radical and the superoxide anion scavenging activities of fluvastatin and its metabolites were evaluated using an electron spin resonance spectrometer. Fluvastatin and its metabolites showed superoxide anion scavenging activity in the hypoxanthine-xanthine oxidase system and a strong scavenging effect on the hydroxyl radical produced from Fenton's reaction. Protective effects of fluvastatin on ROS-induced DNA damage of CHL/IU cells were assessed using the single-cell gel electrophoresis assay. CHL/IU cells were exposed to either hydrogen peroxide or t-butylhydroperoxide. Fluvastatin and its metabolites showed protective effects on DNA damage as potent as the reference antioxidants, ascorbic acid, trolox, and probucol, though pravastatin and simvastatin did not exert clear protective effects. These observations suggest that fluvastatin and its metabolites may have radical scavenging activity and the potential to protect cells against oxidative DNA damage. Furthermore, ROS are thought to play a major role in the etiology of a wide variety of diseases such as cellular aging, inflammation, diabetes, and cancer development, so fluvastatin might reduce these risks.     

Immunohistochemical localizations of albumin and transferrin accumulated in Rhodamine fibrosarcoma tissue of rats for supporting growth of the tumor cells

Our recent studies indicated that Rhodamine fibrosarcoma (RdF) tissue of rats accumulated large amounts of albumin and transferrin and that these proteins were essential for growth of RdF cells in primary cultures in serum-free medium. Therefore, the localizations of albumin and transferrin accumulated in RdF tissue were examined by immunohistochemical stainings. Both anti-rat albumin IgG and anti-rat transferrin IgG stained the cell surface of the tumor cells strongly, but the intracellular area only weakly.     

Fibroblast colonies in monolayer cultures of human bone marrow

In a liquid culture of human bone marrow, the development of fibroblast colonies takes place on days 6 to 9. Twenty percent fetal calf serum is used as the stimulus for fibroblast colony growth. Human bone marrow cells are plated as 2 × 10₅ cells in the culture. Normal human bone marrow yields 47 ± 4 fibroblasts colonies per 2 × 10₅ cells plated. Bone marrow fibroblast cultures using agar or methylcellulose restrict colony formation. Marked colony suppression was observed in acute leukemia, and a discrete colony number was observed in hypoplastic anemia. This fibroblast culture method should be applied to a larger number of patients to determine whether it has a pathognomonic value and clinical significance.     

Neurotoxicity and physicochemical properties of Abeta mutant peptides from cerebral amyloid angiopathy: implication for the pathogenesis of cerebral amyloid angiopathy and Alzheimer's disease

Cerebral amyloid angiopathy (CAA) due to beta-amyloid (Abeta) is one of the specific pathological features of familial Alzheimer's disease. Abeta mainly consisting of 40- and 42-mer peptides (Abeta40 and Abeta42) exhibits neurotoxicity and aggregative abilities. All of the variants of Abeta40 and Abeta42 found in CAA were synthesized in a highly pure form and examined for neurotoxicity in PC12 cells and aggregative ability. All of the Abeta40 mutants at positions 22 and 23 showed stronger neurotoxicity than wild-type Abeta40. Similar tendency was observed for Abeta42 mutants at positions 22 and 23 whose neurotoxicity was 50-200 times stronger than that of the corresponding Abeta40 mutants, suggesting that these Abeta42 mutants are mainly involved in the pathogenesis of CAA. Although the aggregation of E22G-Abeta42 and D23N-Abeta42 was similar to that of wild-type Abeta42, E22Q-Abeta42 and E22K-Abeta42 aggregated extensively, supporting the clinical evidence that Dutch and Italian patients are diagnosed as hereditary cerebral hemorrhage with amyloidosis. In contrast, A21G mutation needs alternative explanation with the exception of physicochemical properties of Abeta mutants. Attenuated total reflection-Fourier transform infrared spectroscopy spectra suggested that beta-sheet content of the Abeta mutants correlates with their aggregation. However, beta-turn is also a critical secondary structure because residues at positions 22 and 23 that preferably form two-residue beta-turn significantly enhanced the aggregative ability.     

Dose-dependent suppression of tea catechins with a galloyl moiety on postprandial hypertriglyceridemia in rats

Tea has long been believed to be a healthy beverage, and its beneficial effects are almost all attributed to catechins. The effect of catechins on postprandial hypertriglyceridemia in rats was investigated in this study. A lipid emulsion administered orally to rats with (-)-epigallocatechin gallate at a dose of 100 mg/kg resulted in the increase in plasma triacylglycerol being significantly inhibited after 1 and 2 h compared to the case without (-)-epigallocatechin gallate. The effect of (-)-epigallocatechin was weaker than that of (-)-epigallocatechin gallate. A tea extract (THEA-FLAN 90S), mainly composed of catechins with a galloyl moiety, dose-dependently suppressed postprandial triacylglycerol after the administration of a lipid emulsion at doses of 50-200 mg/kg. The administration of the tea extract alone at a dose of 200 mg/kg had no effect on the plasma triacylglycerol level. These results strongly suggest that catechins with a galloyl moiety would be promising agents for suppressing dietary fat absorption through the small intestine.     

Molecular cloning and gene expression of the prox1a and prox1b genes in the medaka,Oryzias latipes

Prox1 is a prospero-related homeobox gene. Prox1 is expressed in various internal organs and is related to those differentiations. Small fishes such as the zebrafish and the medaka are useful model animals in the clarification of the mechanism of development. The zebrafish prox1 is also identified, and it contributes to clarifying the function of prox1. However, it is necessary to note that many genes are duplicated in teleost fishes. In this study, we identified the orthologs of the mammalian prox1 gene in the medaka. The gene was also duplicated in the medaka, and we named it prox1a and prox1b. In silico analysis from the perspective of synteny indicated that medaka prox1a was similar to the prox1 gene of other vertebrates. Medaka prox1a was expressed in all internal organs that we have examined by RT-PCR. In contrast, medaka prox1b expression was limited to the brain, heart, liver, kidney, thymus, gill, testis, and ovary. This suggests that the two prox1 genes do not have a complementary relationship. In addition, we examined their expression patterns during embryonic development using whole-mount in situ hybridization. The expression pattern of prox1a showed a pattern similar to that of zebrafish prox1. In contrast, medaka prox1b was expressed asymmetrically in part of the central nervous system, especially strongly in the right side of the habenula.     

Screening for resistance against Pseudomonas syringae in rice-FOX Arabidopsis lines identified a putative receptor-like cytoplasmic kinase gene that confers resistance to major bacterial and fungal pathogens in Arabidopsis and rice

Approximately 20,000 of the rice-FOX Arabidopsis transgenic lines, which overexpress 13,000 rice full-length cDNAs at random in Arabidopsis, were screened for bacterial disease resistance by dip inoculation with Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). The identities of the overexpressed genes were determined in 72 lines that showed consistent resistance after three independent screens. Pst DC3000 resistance was verified for 19 genes by characterizing other independent Arabidopsis lines for the same genes in the original rice-FOX hunting population or obtained by reintroducing the genes into ecotype Columbia by floral dip transformation. Thirteen lines of these 72 selections were also resistant to the fungal pathogen Colletotrichum higginsianum. Eight genes that conferred resistance to Pst DC3000 in Arabidopsis have been introduced into rice for overexpression, and transformants were evaluated for resistance to the rice bacterial pathogen, Xanthomonas oryzae pv. oryzae. One of the transgenic rice lines was highly resistant to Xanthomonas oryzae pv. oryzae. Interestingly, this line also showed remarkably high resistance to Magnaporthe grisea, the fungal pathogen causing rice blast, which is the most devastating rice disease in many countries. The causal rice gene, encoding a putative receptor-like cytoplasmic kinase, was therefore designated as BROAD-SPECTRUM RESISTANCE 1. Our results demonstrate the utility of the rice-FOX Arabidopsis lines as a tool for the identification of genes involved in plant defence and suggest the presence of a defence mechanism common between monocots and dicots.