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101.
Hiroki Shimura Katsuhiko Itoh Atsushi Sugiyama Sayaka Ichijo Masashi Ichijo Fumihiko Furuya Yuji Nakamura Ken Kitahara Kazuhiko Kobayashi Yasuhiro Yukawa Tetsuro Kobayashi 《PloS one》2012,7(9)
Large quantities of radionuclides have leaked from the Fukushima Daiichi Nuclear Power Plant into the surrounding environment. Effective prevention of health hazards resulting from radiation exposure will require the development of efficient and economical methods for decontaminating radioactive wastewater and aquatic ecosystems. Here we describe the accumulation of water-soluble radionuclides released by nuclear reactors by a novel strain of alga. The newly discovered green microalgae, Parachlorella sp. binos (Binos) has a thick alginate-containing extracellular matrix and abundant chloroplasts. When this strain was cultured with radioiodine, a light-dependent uptake of radioiodine was observed. In dark conditions, radioiodine uptake was induced by addition of hydrogen superoxide. High-resolution secondary ion mass spectrometry (SIMS) showed a localization of accumulated iodine in the cytosol. This alga also exhibited highly efficient incorporation of the radioactive isotopes strontium and cesium in a light-independent manner. SIMS analysis showed that strontium was distributed in the extracellular matrix of Binos. Finally we also showed the ability of this strain to accumulate radioactive nuclides from water and soil samples collected from a heavily contaminated area in Fukushima. Our results demonstrate that Binos could be applied to the decontamination of iodine, strontium and cesium radioisotopes, which are most commonly encountered after nuclear reactor accidents. 相似文献
102.
Arabidopsis thaliana MTP1 is a vacuolar membrane Zn(2+)/H(+) antiporter of the cation diffusion facilitator family. Here we present a structure-function analysis of AtMTP1-mediated transport and its remarkable Zn(2+) selectivity by functional complementation tests of more than 50 mutant variants in metal-sensitive yeast strains. This was combined with homology modeling of AtMTP1 based on the crystal structure of the Escherichia coli broad-specificity divalent cation transporter YiiP. The Zn(2+)-binding sites of EcYiiP in the cytoplasmic C-terminus, and the pore formed by transmembrane helices TM2 and TM5, are conserved in AtMTP1. Although absent in EcYiiP, Cys31 and Cys36 in the extended N-terminal cytosolic domain of AtMTP1 are necessary for complementation of a Zn-sensitive yeast strain. On the cytosolic side of the active Zn(2+)-binding site inside the transmembrane pore, Ala substitution of either Asn258 in TM5 or Ser101 in TM2 non-selectively enhanced the metal tolerance conferred by AtMTP1. Modeling predicts that these residues obstruct the movement of cytosolic Zn(2+) into the intra-membrane Zn(2+)-binding site of AtMTP1. A conformational change in the immediately preceding His-rich cytosolic loop may displace Asn258 and permit Zn(2+) entry into the pore. This would allow dynamic coupling of Zn(2+) transport to the His-rich loop, thus acting as selectivity filter or sensor of cytoplasmic Zn(2+) levels. Individual mutations at diverse sites within AtMTP1 conferred Co and Cd tolerance in yeast, and included deletions in N-terminal and His-rich intra-molecular cytosolic domains, and mutations of single residues flanking the transmembrane pore or participating in intra- or inter-molecular domain interactions, all of which are not conserved in the non-selective EcYiiP. 相似文献
103.
Ito T Watanabe H Yamamichi N Kondo S Tando T Haraguchi T Mizutani T Sakurai K Fujita S Izumi T Isobe T Iba H 《The Biochemical journal》2008,411(1):201-209
104.
Eleven microsatellite markers were isolated and characterized for the ice goby, Leucopsarion petersii, from genomic libraries enriched for (ATG)(9) and (CA)(16) . Twenty individuals from a single population were used to screen polymorphism in these loci. The number of alleles per locus and observed heterozygosity ranged from four to 22 and from 0.35 to 1.00, respectively. All loci did not significantly deviated from Hardy-Weinberg equilibrium, and there was no evidence of linkage disequilibrium between all loci-pairs. These loci showed Mendelian inheritance in a full-sib family. The high level of polymorphism of these loci will be useful for studies of population genetics. 相似文献
105.
Shinomura T Nakamura S Ito K Shirasawa S Höök M Kimura JH 《The Journal of biological chemistry》2008,283(48):33658-33664
Follicular dendritic cell-secreted protein (FDC-SP) is a small secretory protein having structural similarities to statherin, a protein in saliva thought to play a role in calcium retention in saliva. In contrast, FDC-SP is thought to play a role in the immune system associated with germinal centers. We report here the very specific expression of FDC-SP in junctional epithelium at the gingival crevice. This region is very important for the host defense against pathogens and for periodontal protection. To be able to better understand the function of FDC-SP, we developed a novel gene expression system that exploited gene trapping and site-specific gene integration to introduce the protein into a mammalian cell culture system. Using this system we were able to express FDC-SP as a fusion protein with green fluorescent protein in an osteogenic progenitor cell line with long term stability, which we then used to find that the fusion protein specifically adsorbs onto mineral deposits and the surface of hydroxyapatite particles exogenously added to the culture. This adsorption was highly dependent on the structural integrity of FDC-SP. These results suggest that FDC-SP may play an important role, adsorbing onto the surface of cementum and alveolar bone adjacent to periodontal ligament and onto tooth surface at the gingival crevice. 相似文献
106.
107.
Yokoyama U Minamisawa S Quan H Akaike T Suzuki S Jin M Jiao Q Watanabe M Otsu K Iwasaki S Nishimaki S Sato M Ishikawa Y 《The Journal of biological chemistry》2008,283(42):28702-28709
We have demonstrated that chronic stimulation of the prostaglandin E2-cAMP-dependent protein kinase A (PKA) signal pathway plays a critical role in intimal cushion formation in perinatal ductus arteriosus (DA) through promoting synthesis of hyaluronan. We hypothesized that Epac, a newly identified effector of cAMP, may play a role in intimal cushion formation (ICF) in the DA distinct from that of PKA. In the present study, we found that the levels of Epac1 and Epac2 mRNAs were significantly up-regulated in the rat DA during the perinatal period. A specific EP4 agonist, ONO-AE1-329, increased Rap1 activity in the presence of a PKA inhibitor, PKI-(14-22)-amide, in DA smooth muscle cells. 8-pCPT-2'-O-Me-cAMP (O-Me-cAMP), a cAMP analog selective to Epac activator, promoted migration of DA smooth muscle cells (SMC) in a dose-dependent manner. Adenovirus-mediated Epac1 or Epac2 gene transfer further enhanced O-Me-cAMP-induced cell migration, although the effect of Epac1 overexpression on cell migration was stronger than that of Epac2. In addition, transfection of small interfering RNAs for Epac1, but not Epac2, significantly inhibited serum-mediated migration of DA SMCs. In the presence of O-Me-cAMP, actin stress fibers were well organized with enhanced focal adhesion, and cell shape was widely expanded. Adenovirus-mediated Epac1, but not Epac2 gene transfer, induced prominent ICF in the rat DA explants when compared with those with green fluorescent protein gene transfer. The thickness of intimal cushion became significantly greater (1.98-fold) in Epac1-overexpressed DA. O-Me-cAMP did not change hyaluronan production, although it decreased proliferation of DA SMCs. The present study demonstrated that Epac, especially Epac1, plays an important role in promoting SMC migration and thereby ICF in the rat DA. 相似文献
108.
In the thermophilic cytochrome P450 from the thermoacidophilic crenarchaeon Sulfolobus tokodaii strain 7 (P450st), a phenylalanine residue at position 310 and an alanine residue at position 320 are located close to the heme thiolate ligand, Cys317. Single site-directed mutants F310A and A320Q and double mutant F310A/A320Q have been constructed. All mutant enzymes as well as wild-type (WT) P450st were expressed at high levels. The substitution of F310 with Ala and of A320 with Gln induced shifts in redox potential and blue shifts in Soret absorption of ferrous-CO forms, while spectral characterization showed that in the resting state, the mutants almost retained the structural integrity of the active site. The redox potential of the heme varied as follows: -481 mV (WT), -477 mV (A320Q), -453 mV (F310A), and -450 mV (F310A/A320Q). The trend in the Soret band of the ferrous-CO form was as follows: 450 nm (WT) < 449 nm (A320Q) < 446 nm (F310A) < 444 nm (F310A/A320Q). These results established that the reduction potential and electron density on the heme iron are modulated by the Phe310 and Ala320 residues in P450st. The electron density on the heme decreases in the following order: WT > A320Q > F310A > F310A/A320Q. The electron density on the heme iron infers an essential role in P450 activity. The decrease in electron density interferes with the formation of a high-valent oxo-ferryl species called Compound I. However, steady-state turnover rates of styrene epoxidation with H2O2 show the following trend: WT approximately equal to A320Q < F310A approximately equal to F310A/A320Q. The shunt pathway which can provide the two electrons and oxygen required for a P450 reaction instead of NAD(P)H and dioxygen can rule out the first and second heme reduction in the catalytic process. Because the electron density on the heme iron might be deeply involved in the k cat values in this system, the intermediate Compound 0 which is the precursor species of Compound I mainly appears to participate dominantly in epoxidation with H2O2. 相似文献
109.
Spermosin, a trypsin-like protease from ascidian sperm: cDNA cloning, protein structures and functional analysis. 总被引:1,自引:0,他引:1
Eri Kodama Tadashi Baba Nobuhisa Kohno Sayaka Satoh Hideyoshi Yokosawa Hitoshi Sawada 《European journal of biochemistry》2002,269(2):657-663
We have previously reported that two trypsin-like enzymes, acrosin and spermosin, play key roles in sperm penetration through the vitelline coat of the ascidian (Urochordata) Halocynthia roretzi [Sawada et al. (1984), J. Biol. Chem. 259, 2900-2904; Sawada et al. (1984), Dev. Biol. 105, 246-249]. Here, we show the amino-acid sequence of the ascidian preprospermosin, which is deduced from the nucleotide sequence of the isolated cDNA clone. The isolated ascidian preprospermosin cDNA consisted of 1740 nucleotides, and an open reading frame encoding 388 amino acids, which corresponds to a molecular mass of 41 896 Da. By sequence alignment, it was suggested that His178, Asp230 and Ser324 make up a catalytic triad and that ascidian spermosin be classified as a novel trypsin family member. The mRNA of preprospermosin is specifically expressed in ascidian gonads but not in other tissues. Purified spermosin consists of 33- and 40-kDa bands as determined by SDS/PAGE under nonreducing conditions. The 40-kDa spermosin consists of a heavy chain (residues 130-388) and a long light chain designated L1 (residues 23-129), whereas the 33-kDa spermosin includes the same heavy chain and a shorter light chain designated L2 (residues 97-129). The L1 chain contains a proline-rich region, designated L1(DeltaL2) which is lacking in L2. Investigation with the glutathione-S-transferase (GST)-spermosin-light-chain fusion proteins, including GST-L1, GST-L2, and GST-L1(DeltaL2), revealed that the proline-rich region in the L1 chain binds to the vitelline coat of ascidian eggs. Thus, we propose that sperm spermosin is a novel trypsin-like protease that binds to the vitelline coat and also plays a part in penetration of sperm through the vitelline coat during ascidian fertilization. 相似文献
110.
The mate choice and mating pattern of a benthic goby Rhinogobius sp. CB (cross band type) were investigated in the Kamo River, Shikoku, Japan. During the breeding season, gravid females assumed a nuptial color and either males or females initiated a courtship display. Males preferentially courted a female of similar size to lead her to his nest, whereas females courted more frequently when they encountered a large male. Eggs in any one nest were always at the same developmental stage. Sampling data of nesting males and females indicated that, in more than half the nests, males gathered more than one female before spawning. In some nests with eggs, two or three females had spent ovaries, indicating that the eggs were laid by multiple females within a short span of time. However, a comparison between the total number of eggs which females would spawn in one nest and the number of eggs actually deposited suggested that eggs were contributed by one female in most nests. This low level of polygyny in spite of multiple female availability is attributed to a limited available spawning area of the nest. 相似文献