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971.
H. Nagasaki R. Yamada R. Konno Y. Yasumura A. Iwashima 《Cellular and molecular life sciences : CMLS》1990,46(5):468-470
Summary A mutant mouse strain ddY/DAO– lacks D-amino acid oxidase activity and accumulates free neutral D-amino acids in its tissues. In this study, D-aspartate oxidase activity and D-aspartate content in the tissues of these mutant mice were compared with those of normal mice. No significant difference was observed, indicating that the metabolism of acidic D-amino acids was unaffected in the mutant. 相似文献
972.
Neutral free D-amino acid contents in the serum, kidney, liver, brain, small intestine and urine in germ-free mice and those in specific pathogen-free mice were compared. No significant difference was found. This strongly suggests that the free D-amino acids which were shown to be present in mice in our previous work did not originate from the enteric microbial flora. 相似文献
973.
Gene conversion in the chicken immunoglobulin locus: A paradigm of homologous recombination in higher eukaryotes 总被引:4,自引:0,他引:4
Gene conversion was first defined in yeast as a type of homologous recombination in which the donor sequence does not change. In chicken B cells, gene conversion builds the antigen receptor repertoire by introducing sequence diversity into the immunoglobulin genes. Immunoglobulin gene conversion continues at high frequency in an avian leukosis virus induced chicken B cell line. This cell line can be modified by homologous integration of transfected DNA constructs offering a model system for studying gene conversion in higher eukaryotes. In search for genes which might participate in chicken immunoglobulin gene conversion, we have identified chicken counterparts of the yeastRAD51, RAD52, andRAD54 genes. Disruption and overexpression of these genes in the chicken B cell line may clarify their role in gene conversion and gene targeting. 相似文献
974.
T. Zhang L.J. Fu J. Gao Y. P. Wu H.Q. Wu 《复旦学报(自然科学版)》2005,44(5):903-904
Silicon has been regarded as one of the most promising anode materials for Li-ion batteries. Its theoretical capacity (4 000 mAh/g) is much higher than that of the commercialized graphite (372 mAh/g). However, the cycle performance of silicon is poor due to the severe volume expansion and shrinkage during Li^+ insertion/extraction which results in pulverization of Si particles, eventually losing its Li^+ storage ability. To solve this problem, nanosized Si particles were utilized and achieved a partial improvement by reducing the absolute volume change. Nevertheless, a new problem was encountered with nanosized material that small Si particles were aggregated to be larger one during Li^+ insertion/extraction, and then pulverized again. In this work, we have succeeded to improve the cycle performance of nanosized Si particles by synthesis of carbon coated silicon nanopartiele. 相似文献
975.
M. Hiramoto Y. Fujimoto K. Kakinuma N. Ikekawa E. Ohnishi 《Cellular and molecular life sciences : CMLS》1988,44(7):623-625
Summary Two novel ecdysteroid conjugates, 2,22-dideoxy-20-hydroxyecdysone 3-phosphate (1) and bombycosterol 3-phosphate (2), as well as four known ecdysteroid 22-phosphate esters, have been isolated and characterized from the ovaries of the silkworm,Bombyx mori. 相似文献
976.
G. D. Prestwich J. F. Carvalho Y. -S. Ding D. E. Hendricks 《Cellular and molecular life sciences : CMLS》1986,42(8):964-966
Summary Substitution of fluorine for the aldehydic hydrogen provides behaviorally active, chemically reactive pheromone mimics. In male moths of the tobacco budwormHeliothis virescens, Z9–14:Acf and Z11–16:Acf cause hyperactivity and irreversible extension of the genitalia in over 80% of treated moths. In addition, a combination of the two components leads to 10–50% of the pairs involving one treated partner becoming locked in copula.Supported by NSF grant PCM-8112755 and DMB-8316931, by a Fellowship from the Alfred P. Sloan Foundation (1981–85), and by Teacher-Scholar Grant from the Camille and Henry Dreyfus Foundation (1981–86) to G.D.P. Address correspondence to G.D.P. 相似文献
977.
H. Kobayashi T. Mizuki Y. Koda M. Okazaki A. Kuroiwa F. Izumi 《Cellular and molecular life sciences : CMLS》1991,47(3):245-247
Summary Protein kinase C in rat cerebral microvessels was characterized. By hydroxyapatite column chromatography, protein kinase C in the soluble fraction was resolved into two major peaks corresponding to type II and III enzymes, in the proportions of 57% and 38%, respectively. Since each subtype is considered to have a distinct role, the high proportion of type II enzyme found in this study suggests that this type may be involved in specific functions of the cerebral microvessels. 相似文献
978.
The c-erb-A protein is a high-affinity receptor for thyroid hormone 总被引:143,自引:0,他引:143
J Sap A Mu?oz K Damm Y Goldberg J Ghysdael A Leutz H Beug B Vennstr?m 《Nature》1986,324(6098):635-640
979.
Antimutagenic unusual amino acids from plants 总被引:2,自引:0,他引:2
Five unusual amino acids were identified as antimutagens against spontaneous mutation of Salmonella typhimurium TA100: L-azetidine-2-carboxylic acid (1) from Liliaceae plants, alpha-(methylenecyclopropyl)glycine (2) from Litchi chinensis seeds, and 2-amino-4-methylhex-5-ynoic acid (3), hypoglycin A (4), and (2S,4R)-2-amino-4-hydroxyhept-6-ynoic acid (5) from Euphoria longana seeds. The absolute stereochemistry of 5 was determined by its chiral synthesis from L-allylglycine, proving that 5 is the C-4 epimer of the amino acid previously isolated from dried longan seeds. 相似文献
980.
Enhancers are cis-acting control elements which can stimulate at a distance the activity of a variety of eukaryotic promoters. First identified as a repeated 72 base pair (bp) sequence upstream of the simian virus 40 (SV40) early gene promoter, enhancers have since been shown to be associated with numerous other viral and cellular genes. Although there are no strong homologies between the sequences of different enhancers, a number of short and degenerate consensus sequences have been identified, including the 'core' element GTGGA/TA/TA/TG and stretches of alternating purines and pyrimidines which may have the potential to form left-handed Z DNA. To study the functional significance of two alternating purine and pyrimidine sequences in the SV40 enhancer, we have introduced various combinations of point mutations into a modified SV40 enhancer which contained only one copy of the 72 bp element (W.H., Y.G., A. Nordheim and A. Rich, unpublished results); one of these combinations impaired both the activity of the enhancer and growth of SV40. We describe here the structure of 18 revertants of this mutant and suggest that in each of the 18 revertants, the defects of the original mutant have been overcome by simple tandem duplications in the enhancer region, all of which include the 'core' element. 相似文献