Phycobilisome model with novel skeleton-like structures in a glaucocystophyte Cyanophora paradoxa

Phycobilisome (PBS) is a photosynthetic antenna supercomplex consisting of a central core subcomplex with several peripheral rods radiating from the core. Subunit structure of PBS was studied in a glaucocystophyte Cyanophora paradoxa strain NIES 547. Subunit composition of PBS was identified by N-terminal sequencing and genes for the subunits were determined by homology search of databases. They included rod linker proteins CpcK1 and CpcK2, rod-core linker proteins CpcG1 and CpcG2, and core linker proteins ApcC1 and ApcC2. Subfractionation by native polyacrylamide gel electrophoresis provided evidence for novel subcomplexes (ApcE/CpcK1/CpcG2/ApcA/ApcB/CpcD and ApcE/CpcK2/CpcG1/ApcA/ApcB), which connect rod and core subcomplexes. These skeleton-like structures may serve as a scaffold of the whole PBS assembly. Different roles of ApcC1 and ApcC2 were also suggested. Based on these findings, structural models for PBS were proposed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.     

<i>Acetobacter okinawensis</i> sp. nov., <i>Acetobacter papayae</i> sp. nov., and <i>Acetobacter persicus</i> sp. nov.; novel acetic acid bacteria isolated from stems of sugarcane, fruits, and a flower in Japan

Eleven strains of acetic acid bacteria were isolated from stems of sugarcane, fruits, and a flower in Japan. The isolates were separated into three groups, Groups I, II, and III, in the genus Acetobacter according to phylogenetic analysis based on 16S rRNA sequences. The isolates had sequence similarities of 99.8-100% within the Group, 99.3-99.6% to those of the type strains of each related Acetobacter species, and less than 98.4% to those of the type strains of other Acetobacter species. Genomic DNA G+C contents of Groups I, II, and III were 59.2-59.4, 60.5-60.7, and 58.7-58.9 mol%, respectively. The isolates in the Group showed high values of DNA-DNA relatedness to each other, but low values less than 46% to the type strains of related Acetobacter species. A good correlation was found between the three Groups and groups based on DNA G+C contents and DNA-DNA relatedness. All the strains had Q-9 as the main component, and Q-8 and Q-10 as minor components. The isolates in the three Groups did not completely match with any Acetobacter species on catalase reaction, the production of ketogluconic acids from D-glucose, growth on ammoniac nitrogen with ethanol (Hoyer-Frateur medium and Frateur modified Hoyer medium), growth on 30% (w/v) D-glucose, growth in 10% (v/v) ethanol, or DNA G+C contents. On the basis of phylogenetic relationships in the genus Acetobacter and chemosystematic and phenotypic characteristics, the three Groups were regarded as novel species in the genus Acetobacter. Acetobacter okinawensis sp. nov. is proposed for Group I, Acetobacter papayae sp. nov. for Group II, and Acetobacter persicus sp. nov. for Group III.     

Mitochondrial haplotypes reveal olive fly (Bactrocera oleae) population substructure in the Mediterranean

The olive fly (Bactrocera oleae) is the most important olive tree (Olea europaea) pest. In the Mediterranean basin, where 98?% of its main hosts are concentrated, it causes major agricultural losses, due to its negative effect on production and quality of both olive and olive oil. Previous phylogeographic analyses have established that Mediterranean olive fly populations are distinct from other Old World populations, but did not agree on the specific population substructure within this region. In order to achieve a higher resolution of the diversity of olive fly populations, particularly in Central and Western Mediterranean (home to 70?% of the world production), we comparatively analyzed a set of samples from Portugal in the context of published mitochondrial sequences across the species' worldwide range. Strong evidence of population substructure was found in the Central and Western Mediterranean area, with two clearly separate phylogenetic branches. Together with previously published data, our results strongly support the existence of at least three distinct Mediterranean populations of the olive fly, raise the possibility of additional regional substructure and suggest specific avenues for future research. This knowledge can be instrumental in the development of better management and control strategies for a major pest of Mediterranean agriculture.     

Xenon and sevoflurane provide analgesia during labor and fetal brain protection in a perinatal rat model of hypoxia-ischemia

It is not possible to identify all pregnancies at risk of neonatal hypoxic-ischemic encephalopathy (HIE). Many women use some form of analgesia during childbirth and some anesthetic agents have been shown to be neuroprotective when used as analgesics at subanesthetic concentrations. In this study we sought to understand the effects of two anesthetic agents with presumptive analgesic activity and known preconditioning-neuroprotective properties (sevoflurane or xenon), in reducing hypoxia-induced brain damage in a model of intrauterine perinatal asphyxia. The analgesic and neuroprotective effects at subanesthetic levels of sevoflurane (0.35%) or xenon (35%) were tested in a rat model of intrauterine perinatal asphyxia. Analgesic effects were measured by assessing maternal behavior and spinal cord dorsal horn neuronal activation using c-Fos. In separate experiments, intrauterine fetal asphyxia was induced four hours after gas exposure; on post-insult day 3 apoptotic cell death was measured by caspase-3 immunostaining in hippocampal neurons and correlated with the number of viable neurons on postnatal day (PND) 7. A separate cohort of pups was nurtured by a surrogate mother for 50 days when cognitive testing with Morris water maze was performed. Both anesthetic agents provided analgesia as reflected by a reduction in the number of stretching movements and decreased c-Fos expression in the dorsal horn of the spinal cord. Both agents also reduced the number of caspase-3 positive (apoptotic) neurons and increased cell viability in the hippocampus at PND7. These acute histological changes were mirrored by improved cognitive function measured remotely after birth on PND 50 compared to control group. Subanesthetic doses of sevoflurane or xenon provided both analgesia and neuroprotection in this model of intrauterine perinatal asphyxia. These data suggest that anesthetic agents with neuroprotective properties may be effective in preventing HIE and should be tested in clinical trials in the future.     

Comparative angiogenic activities of induced pluripotent stem cells derived from young and old mice

Advanced age is associated with decreased stem cell activity. However, the effect of aging on the differentiation capacity of induced pluripotent stem (iPS) cells into cardiovascular cells has not been fully clarified. We investigated whether iPS cells derived from young and old mice are equally capable of differentiating into vascular progenitor cells, and whether these cells regulate vascular responses in vivo. iPS cells from mouse embryonic fibroblasts (young) or 21 month-old mouse bone marrow (old) were used. Fetal liver kinase-1 positive (Flk-1(+)) cells, as a vascular progenitor marker, were induced after 3 to 4 days of culture from iPS cells derived from young and old mice. These Flk-1(+) cells were sorted and shown to differentiate into VE-cadherin(+) endothelial cells and α-SMA(+) smooth muscle cells. Tube-like formation was also successfully induced in both young and old murine Flk-1(+) cells. Next, hindlimb ischemia was surgically induced, and purified Flk-1(+) cells were directly injected into ischemic hindlimbs of nude mice. Revascularization of the ischemic hindlimb was significantly accelerated in mice transplanted with Flk-1(+) cells derived from iPS cells from either young or old mice, as compared to control mice as evaluated by laser Doppler blood flowmetry. The degree of revascularization was similar in the two groups of ischemic mice injected with iPS cell-derived Flk-1(+) cells from young or old mice. Transplantation of Flk-1(+) cells from both young and old murine iPS cells also increased the expression of VEGF, HGF and IGF mRNA in ischemic tissue as compared to controls. iPS cell-derived Flk-1(+) cells differentiated into vascular progenitor cells, and regulated angiogenic vascular responses both in vitro and in vivo. These properties of iPS cells derived from old mice are essentially the same as those of iPS cells from young mice, suggesting the functionality of generated iPS cells themselves to be unaffected by aging.     

Relationship between BMI and all-cause mortality in Japan: NIPPON DATA80

As body composition in Asian populations is largely different from Western populations, a healthy BMI could also differ between the two populations. Thus, further study is needed to determine whether a healthy BMI in Asians should be lower than Western populations, as recommended by the World Health Organization (WHO). We investigated the relationship between BMI and mortality in a sample of 8,924 Japanese men and women without stroke or heart disease. During 19 years of follow-up, 1,718 deaths were observed. We found a U-shaped relationship between BMI and fatal events. Risk of total mortality was highest in participants with BMI <18.5 kg/m(2) and lowest in participants with BMI 23.0-24.9 kg/m(2). These findings persisted even after excluding the first 5 years of follow-up with a focus on healthy participants who never smoked, were aged <70 years, and had total cholesterol (TC) levels >or=4.1 mmol/l (N=3712). For both the full sample and healthy participants, all-cause mortality risk did not differ between BMI ranges 21.0-22.9 and 23.0-24.9 kg/m(2). Our findings do not support the recent WHO implications that BMIs <23.0 kg/m(2) is healthy for Asians. Therefore, further studies are needed to identify an optimal BMI range for Asia.     

Direct detection of the interaction between recombinant soluble extracellular regions in the heterodimeric metabotropic gamma-aminobutyric acid receptor

The gamma-aminobutyric acid, type B (GABAB) receptor is a heterodimeric receptor consisting of two complementary subunits, GABAB1 receptor (GBR1) and GABAB2 receptor (GBR2). GBR1 is responsible for GABA binding, whereas GBR2 is considered to perform a critical role in signal transduction toward downstream targets. Therefore, precise communication between GBR1 and GBR2 is thought to be essential for the proper signal transduction process. However, biochemical data describing the interaction of the two subunits, especially for the extracellular regions, are not sufficient. Thus we began by developing a protein expression system of the soluble extracellular regions. One of the soluble recombinant GBR1 proteins exhibited a ligand binding ability, which is similar to that of the full-length GBR1, and thus the ligand-binding domain was determined. Direct interaction between GBR1 and GBR2 extracellular soluble fragments was confirmed by co-expression followed by affinity column chromatography and a sucrose density gradient sedimentation. In addition, we also found homo-oligomeric states of these soluble extracellular regions. The interaction between the two soluble extracellular regions caused the enhancement of the agonist affinity for GBR1 as previously reported in a cell-based assay. These results not only open the way to future structural studies but also highlight the role of the interaction between the extracellular regions, which controls agonist affinity to the heterodimeric receptor.