(A.M., C.M.) This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO 2 -limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO 2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO 2 -limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADHdependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO 2 are not available.In photosynthesis, photon energy absorbed by PSI and PSII in thylakoid membranes oxidizes the reaction center chlorophylls (Chls), P700 in PSI and P680 in PSII, and drives the photosynthetic electron transport (PET) system. In PSII, water is oxidized to oxygen as the oxidized P680 accepts electrons from water. These electrons then reduce the cytochrome b 6 /f complex through plastoquinone (PQ) in the thylakoid membranes. Photooxidized P700 in PSI accepts electrons from the reduced cytochrome b 6 /f complex through plastocyanin or cytochrome c 6 . Electrons released in the photooxidation of P700 are used to produce NADPH through ferredoxin and ferredoxin NADP + reductase. Thus, electrons flow from water to NADPH in the so-called photosynthetic linear electron flow (LEF). Importantly, LEF induces a proton gradient across the thylakoid membranes, which provides the driving force for ATP production by ATP synthases in the thylakoid membranes. NADPH and ATP serve as chemical energy donors in the photosynthetic carbon reduction cycle (Calvin cycle).It recently has been proposed that, in cyanobacteria, the photorespiratory carbon oxidation cycle (photorespiration) functions simultaneously with the Calvin cycle to recover carbon for the regeneration of ribulose-1,5-bisphosphate, one of the substrates of Rubisco (Hagemann et al., 2013). Rubisco catalyzes the primary reactions of carbon reduction as well as oxidation cycles. However, the presence of a specific carbon concentration mechan...

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BACKGROUND: Few studies have examined the association of perceived health with socio-economic status, especially income, and social isolation and support in Japan. The purpose of this study is to clarify the associations among perceived health, lifestyle, and socio-economic status, as well as social isolation and support factors, in middle-aged and elderly Japanese. METHODS: Subjects were 9,650 participants aged 47-77 years who completed a self-administered questionnaire in 2000 in the second survey of a population-based cohort (the Komo-Ise study). The questionnaire included items on sociodemographic and socio-economic factors, social isolation and support, lifestyle, past history of chronic disease and perceived health. Perceived health was dichotomized into excellent or good health and fair or poor health. A logistic regression analysis was used to determine the odds ratios of socio-economic status, social characteristics and lifestyle in relation to self-reported fair or poor health. RESULTS: We found that household income, physical activity, sleeping, smoking habit, and BMI had a strong association with self-reported fair or poor health in middle-aged and elderly Japanese men and women. Male subjects tended to report fair or poor health as household income decreased. The results for women differed in that social isolation and low social support had a stronger association for self-reported fair or poor health than low household income. CONCLUSIONS: The results indicated that perceived health was associated with socio-economic and social characteristics among middle-aged and elderly residents in Japan.

Abstract. Epigenetic alteration is an emerging paradigm underlying the long-term effects of chemicals on gene functions. Various chemicals, including organophosphate insecticides and heavy metals, have been detected in the human fetal environment. Epigenetics by DNA methylation and histone modifications, through dynamic chromatin remodeling, is a mechanism for genome stability and gene functions. To investigate whether such environmental chemicals may cause epigenetic alterations, we studied the effects of selected chemicals on morphological changes in heterochromatin and DNA methylation status in mouse ES cells (ESCs). Twenty-five chemicals, including organophosphate insecticides, heavy metals and their metabolites, were assessed for their effect on the epigenetic status of mouse ESCs by monitoring heterochromatin stained with 4′,6-diamino-2-phenylindole (DAPI). The cells were surveyed after 48 or 96 h of exposure to the chemicals at the serum concentrations of cord blood. The candidates for epigenetic mutagens were examined for the effect on DNA methylation at genic regions. Of the 25 chemicals, five chemicals (diethyl phosphate (DEP), mercury (Hg), cotinine, selenium (Se) and octachlorodipropyl ether (S-421)) caused alterations in nuclear staining, suggesting that they affected heterochromatin conditions. Hg and Se caused aberrant DNA methylation at gene loci. Furthermore, DEP at 0.1 ppb caused irreversible heterochromatin changes in ESCs, and DEP-, Hg-and S-421-exposed cells also exhibited impaired formation of the embryoid body (EB), which is an in vitro model for early embryos. We established a system for assessment of epigenetic mutagens. We identified environmental chemicals that could have effects on the human fetus epigenetic status. Key words: DNA methylation, Embryoid body, Epigenetic mutagens, ES cells, Heterochromatin (J. Reprod. Dev. 57: [507][508][509][510][511][512][513][514][515][516][517] 2011) any chemicals have been widely used in the household, agricultural and urban environment, and there are various environmental chemicals in the fetal growth environment: organophosphate insecticides (chlorpyrifos), perfluorooctane sulfonate (PFOS), di(2-ethylhexyl)phthalate (DEHP), elements of tobacco smoke (nicotine and cotinine) and heavy metals (lead (Pb), cadmium (Cd) and mercury (Hg)) [1][2][3][4][5]. Hg exposure occurs in the daily intake of rice in China [6]. Prenatal exposure to environmental chemicals such as organophosphate insecticides, tobacco smoke, heavy metals and perfluorinated compounds (PFCs) is associated with fetal growth restriction and low birth weight of infants [7][8][9][10]. The concentration of chemicals detected in the fetal environment is, however, relatively low (around 0.1-10 ppb level) and far from the levels reported in pharmacological studies. Such a low concentration may accumulate in the fetus and placenta and affect fetal growth [11][12][13][14], and alternatively, some chemicals may have long-term effects on gene functions and stability even at a low concentration ...

Islets were microencapsulated in agarose gel for examination of the possible use of microencapsulated islets as a bioartificial pancreas. Microencapsulated islets secreted insulin into the culture medium (RPMI-1640) and could rapidly increase their insulin release in response to a glucose challenge even after greater than 100 days. Hamster islets in groups of 400-1000 encapsulated in microbeads containing 11-14% (wt/wt) agarose were xenogenically transplanted into the peritoneal cavity of five diabetic mice. The longest normoglycemic period in these mice was 53 days, which was markedly longer than the normoglycemic period obtained by nonencapsulated islets. Agarose seems to be a suitable basic material for encapsulating islets, because the islets can easily be microencapsulated without any adverse effect on the islet function.