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111.
112.
Eriko Kage-Nakadai Rieko Imae Yuji Suehiro Sawako Yoshina Sayaka Hori Shohei Mitani 《PloS one》2014,9(12)
Conditional knockout (cKO) based on site-specific recombination (SSR) technology is a powerful approach for estimating gene functions in a spatially and temporally specific manner in many model animals. In Caenorhabditis elegans (C. elegans), spatial- and temporal-specific gene functions have been largely determined by mosaic analyses, rescue experiments and feeding RNAi methods. To develop a systematic and stable cKO system in C. elegans, we generated Cre recombinase expression vectors that are driven by various tissue-specific or heat-shock promoters. Validation using Cre-mediated fluorescence protein inactivation or activation systems demonstrated successful Cre-dependent loxP excision. We established a collection of multi-copy Cre transgenic strains for each evaluated vector. To evaluate our Cre/loxP-based cKO system, we generated sid-1 deletion mutants harboring floxed sid-1 single-copy integration (SCI) using ultraviolet trimethylpsoralen (UV/TMP) methods. sid-1 mutants that were rescued by the floxed sid-1 SCI were then crossed with the Pdpy-7::Cre strain for cKO in the hypodermis. The sid-1 cKO animals were resistant to bli-3 RNAi, which causes the Bli-phenotyple in the hypodermis, but they were sensitive to unc-22 RNAi, which leads to twitching of the body wall muscle. Our system, which is based on the combination of a transgenic Cre collection, pre-existing deletion mutants, and UV/TMP SCI methods, provided a systematic approach for cKO in C. elegans. 相似文献
113.
Mate choice and cannibalism in a natural population of a stream goby,Rhinogobius sp. 总被引:2,自引:2,他引:0
Breeding ecology of the stream goby,Rhinogobius sp. LD (Large Dark), was investigated under natural conditions. Males selectively courted females of similar size to lead
them to the nests, whereas females followed courting males preferentially when the relative male size was greater. Male-male
competition for a female was relatively infrequent and not severe. Developmental stages of eggs and egg numbers in one nest
indicated that males receive 1–3 clutches during one breeding cycle. Males guarding multiple clutches frequently ate some
of the eggs, but those guarding single clutches rarely did so. Gravid females in the nest also frequently cannibalized eggs
laid by a previous female, probably in order to extend the area available for egg deposition. Mate choice in this species
is discussed in relation to paternal ability, limitation of available spawning area and the female-biased sex ratio. 相似文献
114.
Yamada C Kijima K Ishihara S Miwa C Wada K Okada T Fukuyama K Kumagai H Suzuki H 《Applied and environmental microbiology》2008,74(11):3400-3409
7-Aminocephalosporanic acid (7-ACA) is an important material in the production of semisynthetic cephalosporins, which are the best-selling antibiotics worldwide. 7-ACA is produced from cephalosporin C via glutaryl-7-ACA (GL-7-ACA) by a bioconversion process using d-amino acid oxidase and cephalosporin acylase (or GL-7-ACA acylase). Previous studies demonstrated that a single amino acid substitution, D433N, provided GL-7-ACA acylase activity for gamma-glutamyltranspeptidase (GGT) of Escherichia coli K-12. In this study, based on its three-dimensional structure, residues involved in substrate recognition of E. coli GGT were rationally mutagenized, and effective mutations were then combined. A novel screening method, activity staining followed by a GL-7-ACA acylase assay with whole cells, was developed, and it enabled us to obtain mutant enzymes with enhanced GL-7-ACA acylase activity. The best mutant enzyme for catalytic efficiency, with a k(cat)/K(m) value for GL-7-ACA almost 50-fold higher than that of the D433N enzyme, has three amino acid substitutions: D433N, Y444A, and G484A. We also suggest that GGT from Bacillus subtilis 168 can be another source of GL-7-ACA acylase for industrial applications. 相似文献
115.
116.
Complete genomic sequence of nitrogen-fixing symbiotic bacterium Bradyrhizobium japonicum USDA110. 总被引:7,自引:0,他引:7
Takakazu Kaneko Yasukazu Nakamura Shusei Sato Kiwamu Minamisawa Toshiki Uchiumi Shigemi Sasamoto Akiko Watanabe Kumi Idesawa Mayumi Iriguchi Kumiko Kawashima Mitsuyo Kohara Midori Matsumoto Sayaka Shimpo Hisae Tsuruoka Tsuyuko Wada Manabu Yamada Satoshi Tabata 《DNA research》2002,9(6):189-197
The complete nucleotide sequence of the genome of a symbiotic bacterium Bradyrhizobium japonicum USDA110 was determined. The genome of B. japonicum was a single circular chromosome 9,105,828 bp in length with an average GC content of 64.1%. No plasmid was detected. The chromosome comprises 8317 potential protein-coding genes, one set of rRNA genes and 50 tRNA genes. Fifty-two percent of the potential protein genes showed sequence similarity to genes of known function and 30% to hypothetical genes. The remaining 18% had no apparent similarity to reported genes. Thirty-four percent of the B. japonicum genes showed significant sequence similarity to those of both Mesorhizobium loti and Sinorhizobium meliloti, while 23% were unique to this species. A presumptive symbiosis island 681 kb in length, which includes a 410-kb symbiotic region previously reported by G?ttfert et al., was identified. Six hundred fifty-five putative protein-coding genes were assigned in this region, and the functions of 301 genes, including those related to symbiotic nitrogen fixation and DNA transmission, were deduced. A total of 167 genes for transposases/104 copies of insertion sequences were identified in the genome. It was remarkable that 100 out of 167 transposase genes are located in the presumptive symbiotic island. DNA segments of 4 to 97 kb inserted into tRNA genes were found at 14 locations in the genome, which generates partial duplication of the target tRNA genes. These observations suggest plasticity of the B. japonicum genome, which is probably due to complex genome rearrangements such as horizontal transfer and insertion of various DNA elements, and to homologous recombination. 相似文献
117.
Naoshi Yamamoto Sayaka Ohrui Takahiro Okada Tsuyoshi Saitoh Noriki Kutsumura Yasuyuki Nagumo Yoko Irukayama-Tomobe Yasuhiro Ogawa Yukiko Ishikawa Yurie Watanabe Daichi Hayakawa Hiroaki Gouda Masashi Yanagisawa Hiroshi Nagase 《Bioorganic & medicinal chemistry》2019,27(8):1747-1758
Morphinan derivatives lacking the 4,5-epoxy ring were synthesized to examine the participation of the 14-OH group, the 3-OMe group, and the aromaticity of the A-ring in the activity and selectivity for the orexin 1 receptor (OX1R). The assay results and the conformational analyses of the 14-dehydrated and 14-H derivatives suggested that the orientations of the 6-amide side chain and the 17-benzenesulfonyl group would play important roles in the activity for OX1R. In the 6β-derivatives, removal of the 3-OMe group and the reduction of the A-ring significantly decreased the activity toward the OX1R, but these changes did not affect the 6α-derivatives. These results indicate that the 3-OMe group and the A-ring would be essential structural moieties for the 6β-derivatives. 相似文献
118.
Sayaka Arai Hidenori Takahashi Hiroyoshi Takano Atsushi Sakai Shigeyuki Kawano 《Journal of phycology》1998,34(3):477-485
Historically, the genus Nannochloris has been classified using the morphology of cell division, although the mechanics of division remain relatively poorly understood. Nannochloris bacillaris reproduces by binary fission. Microscopic observation with fluorescein isothiocyanate-phalloidin showed that actin filaments localized near the nucleus and appeared as a ring- or beltlike structure in the septum-forming area in the middle of the cell during cell division. In primitive unicellular Chlorophyta such as N. bacillaris, actin is also thought to play important roles in nuclear migration and cell division. The N. bacillaris actin gene has three exons and two introns defined by two exon–intron junctions with splice site consensus sequences. The two introns are located at codons specifying amino acids 3/4 and 47/48. One of these, intron position 3/4, is conserved in the actin gene of Saccharomyces cerevisiae. The actin gene product was predicted to be 378 amino acids long with an estimated molecular weight of 42 kDa. There is only one copy of the actin gene in the N. bacillaris genome. Nannochloris bacillaris has 14 chromosomes that range in size from 230 kb to 3000 kb, and the total size of the genome was estimated to be 20.3 Mb. The actin gene is on either chromosome XI or XII. In a phylogenetic tree based on the actin gene sequence, N. bacillaris diverged before the divergence of Volvox, Chlamydomonas, and higher plants, and very shortly after the radiation of the Rhodophyta. 相似文献
119.
Erwinia persicinus, a new species isolated from plants 总被引:3,自引:0,他引:3
M V Hao D J Brenner A G Steigerwalt Y Kosako K Komagata 《International journal of systematic bacteriology》1990,40(4):379-383
Five strains of a gram-negative, oxidase-negative, facultatively anaerobic, fermentative, motile, rod-shaped bacterium with the general characteristics of the family Enterobacteriaceae were isolated from tomatoes (three strains), a banana, and a cucumber. All of the strains produced a water-soluble pink pigment. As determined by DNA hybridization (hydroxyapatite method) these five strains were 85 to 100% related in 60 and 75 degrees C reactions, and related sequences exhibited 1% or less base sequence divergence, indicating that the organisms are members of a single species. These bacteria were most closely related to Erwinia rhapontici (68 to 72% at 60 degrees C, 42 to 44% at 75 degrees C, 10.5% divergence) and to hybridization group VIII in the Enterobacter agglomerans (Pantoea agglomerans, Erwinia herbicola) complex (64% at 60 degrees C, 32% at 75 degrees C, 14.5% divergence). Phenotypic differentiation from Erwinia rhapontici, which also produces a water-soluble pink pigment, is based on negative reactions by the new species in tests for methyl red, N-acetylglucosamine, DL-tartrate assimilation, and acid production from amygdalin, dulcitol, D-fucose, beta-gentiobiose, alpha-methyl-D-glucoside, glycerol, D-lyxose, melezitose, D-turanose, xylitol, and D-xylose and a positive reaction for acetoin (Voges-Proskauer test). On the basis of these data, the name Erwinia persicinus is proposed for the new organism. The type strain is strain HK 204 (= AJ 2716 = CDC 9108-82 = IAM 12843 = JCM 3704 = ATCC 35998). 相似文献
120.
Sayaka Okuzono Masataka Ishimura Shunsuke Kanno Motoshi Sonoda Noriyuki Kaku Yoshitomo Motomura Hisanori Nishio Utako Oba Masuo Hanada Jun-ichi Fukushi Michiyo Urata Dongchon Kang Hidetoshi Takada Shouichi Ohga 《Annals of clinical microbiology and antimicrobials》2018,17(1):31