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51.
A novel photorespiratory mutant of Arabidopsis thaliana, designatedgld2, was isolated based on a growth requirement for abnormallyhigh levels of atmospheric CO2. Photosynthetic CO2 fixationwas inhibited in the mutant following illumination in air butnot in atmosphere containing 2% O2. Photosynthetic assimilationof 14CO2 in an atmosphere containing 50% O2 resulted in accumulationof 48% of the soluble label in glycine in the mutant comparedto 9% in the wild type. The rate of glycine decarboxylationby isolated mitochondria from the mutant was reduced to 6% ofthe wild type rate. In genetic crosses, the mutant complementedtwo previously described photorespiratory mutants of A. thalianathat accumulate glycine during photosynthesis in air due todefects in glycine decarboxylase (glyD, now designated gld1)and serine transhydroxymethylase (stm). Because glycine decarboxylaseis a complex of four enzymes, these results are consistent witha mutation in a glycine decarboxylase subunit other than thataffected in the gld1 mutant. The two gld loci were mapped tochromosomes 2 and 5, respectively.
3Present address: Department of Crop and Soil Sciences, MichiganState University, East Lansing, MI 48824, U.S.A.
4Present address: Department of Applied Bioscience, Facultyof Agriculture, Hokkaido University, Kita-Ku, Sapporo, 060 Japan
5Present address: Department of Biology, Carnegie Institutionof Washington, 290 Panama Street, Standford, CA 94305, U.S.A. 相似文献
52.
Spatial distribution of root activity and nitrogen fixation in sorghum/pigeonpea intercropping on an Indian Alfisol 总被引:2,自引:0,他引:2
Ito Osamu Matsunaga Ryoichi Tobita Satoshi Rao Theertham P. Devi Y. Gayatri 《Plant and Soil》1993,155(1):341-344
A medium-duration pigeonpea cultivar (ICP 1–6) and a hybrid sorghum (CSH 5) were grown on a shallow Alfisol in monocropping and intercropping systems. Using a monolith method, spatial distribution of nodulation, acetylene reduction activity (ARA) and root respiration were measured.The number, mass and ARA of nodules decreased exponentially with distance from the plant base except at the late reproductive stage. Nodulation and ARA tended to be higher in the intercrop than in the monocrop.Respiration rate of roots increased with distance from the plant base and reached a maximum value at about 20–30 cm. The rate was higher in pigeonpea than in sorghum and also higher in intercrop than in monocrop.This study suggests that pigeonpea roots are physiologically more active than sorghum roots, implying that pigeonpea may become a strong competitor for nutrients in the soil when intercropped. The nitrogen-fixing ability of pigeonpea may be enhanced by intercropping because the sorghum rapidly absorbed inorganic N which would otherwise inhibit N2 fixation. 相似文献
53.
Tsukio Masegi Satoshi Nakamura Masami Fukuoka Kazuo Kitai Yataro Ichikawa Naoki Watanabe Yoshiro Niitsu 《Biotechnology letters》1993,15(11):1107-1110
Summary We prepared various TNF- derivatives by protein engineering techniques. Mutant 471, in which 7 N-terminal amino acids were deleted and Pro8Ser9Asp10 was replaced by ArgLysArg, had a 8-fold higher antitumor activity against mouse L929 cells than wild-type TNF-. The additional substitution of Ala156 or Leu157 by more hydrophobic amino acids enhanced the activity of mutant 471. These results suggested that the combinational mutations in the N- and C-terminal regions of TNF- are effective for the improvement of antitumor activity. 相似文献
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The helicities in various fragments of bovine serum albumin (BSA) were examined in the thermal denaturation and in sodium docecyl sulfate (SDS) denaturation. The thermal denaturation was examined in a temperature range between 2 and 65°C. The helicity decreased with a rise of temperature and it recovered to some degree upon cooling temperature. A rather high reversibility was observed in the BSA fragments, which were located in the N-terminal of the parent protein and then contained the first large loop with no disulfide bridge. The high reversibility was available also for the helicity in the first large loop of the fragment, disulfide bridges of which were reduced. The fragments, which were smaller than one domain, became unstable in the SDS denaturation. The helicities of such fragments decreased in lower SDS concentrations compared with those of the intact BSA and the large fragments, which contained one or more domains. A resistance to the SDS denaturation appeared in the helices of every large loop even after the fragmentation. On the other hand, helicities of the fragments decreased to 20–25% upon the reduction of disulfide bridges. However, the helicities of these fragments increased to 35–40% in the SDS denaturation. 相似文献
58.
Yoriko Masuda Satoshi Haramizu Kasumi Oki Koichiro Ohnuki Tatsuo Watanabe Susumu Yazawa Teruo Kawada Shu-ichi Hashizume Tohru Fushiki 《Journal of applied physiology》2003,95(6):2408-2415
Capsiate is a nonpungent capsaicin analog, a recently identified principle of the nonpungent red pepper cultivar CH-19 Sweet. In the present study, we report that 2-wk treatment of capsiate increased metabolic rate and promoted fat oxidation at rest, suggesting that capsiate may prevent obesity. To explain these effects, at least in part, we examined uncoupling proteins (UCPs) and thyroid hormones. UCPs and thyroid hormones play important roles in energy expenditure, the maintenance of body weight, and thermoregulation. Two-week treatment of capsiate increased the levels of UCP1 protein and mRNA in brown adipose tissue and UCP2 mRNA in white adipose tissue. This dose of capsiate did not change serum triiodothyronine or thyroxine levels. A single dose of capsiate temporarily raised both UCP1 mRNA in brown adipose tissue and UCP3 mRNA in skeletal muscle. These results suggest that UCP1 and UCP2 may contribute to the promotion of energy metabolism by capsiate, but that thyroid hormones do not. 相似文献
59.
Growth Characteristics and Intraspecies Host Specificity of a Large Virus Infecting the Dinoflagellate Heterocapsa circularisquama
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Keizo Nagasaki Yuji Tomaru Kenji Tarutani Noriaki Katanozaka Satoshi Yamanaka Hiroshi Tanabe Mineo Yamaguchi 《Applied microbiology》2003,69(5):2580-2586
The growth characteristics and intraspecies host specificity of Heterocapsa circularisquama virus (HcV), a large icosahedral virus specifically infecting the bivalve-killing dinoflagellate H. circularisquama, were examined. Exponentially growing host cells were more sensitive to HcV than those in the stationary phase, and host cells were more susceptible to HcV infection in the culture when a higher percent of the culture was replaced with fresh medium each day, suggesting an intimate relationship between virus sensitivity and the physiological condition of the host cells. HcV was infective over a wide range of temperatures, 15 to 30°C, and the latent period and burst size were estimated at 40 to 56 h and 1,800 to 2,440 infective particles, respectively. Transmission electron microscopy revealed that capsid formation began within 16 h postinfection, and mature virus particles appeared within 24 h postinfection at 20°C. Compared to Heterosigma akashiwo virus, HcV was more widely infectious to H. circularisquama strains that had been independently isolated in the western part of Japan, and only 5.3% of the host-virus combinations (53 host and 10 viral strains) showed resistance to viral infection. The present results are helpful in understanding the ecology of algal host-virus systems in nature. 相似文献
60.
Bacteria have devised sophisticated signaling systems for elicitinga variety of adaptive responses to their environment, whichare generally referred to as the "two-component regulatory system."The widespread occurrence of the two-component systems in bothprokaryotes and eukaryotes implies that it is a powerful devicefor a wide variety of adaptive responses of cells to their environment.The two-component signal transducers contain one or more ofthree conserved and characteristic phosphotransfer signalingdomains, named the "transmitter, receiver, and alternative transmitter."The recently determined entire genomic sequence of Synechocystissp. strain PCC 6803 allowed us to compile systematically a completelist of genes encoding such two-component signal transductionproteins. The results of such an effort, made in this study,revealed that at least 80 ORFs were identified as members ofthe two-component signal transducers in this single speciesof cyanobacteria. 相似文献