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931.
Lectin-resistant variants of the mouse mammary tumor cell line FM3A in suspension were isolated after multiple-step selection using toxic concentrations of phytohemagglutinin (PHA) and concanavalin A (Con A). In fusion experiments, both PHA- and Con A-resistant lines were found to have lost the ability to yield hybrids with suspension-grown cells, although they were capable of yielding hybrids with monolayer-grown cells. This phenotype of PHA-resistant lines was stable during a long period of culture in the absence of PHA. 相似文献
932.
933.
Kamiya Yuji; Kobayashi Masatomo; Fujioka Shozo; Yamane Hisakazu; Nakayama Ishizue; Sakurai Akira 《Plant & cell physiology》1991,32(8):1205-1210
Prohexadione calcium (BX-112) is a novel plant growth regulatorthat inhibits the late stages of the biosynthesis of gibberellinsin plants. Fourteen kinds of gjbberellin, helminthosporol and'helminthosporic acid were applied simultaneously with BX-112to rice seedlings (Oryza sativa L. ), and their growth-promotingactivities in terms of shoot elongation were examined. The growth-promotingactivities of GA1, GA4, GA18, GA22, GA23, GA38, helminthosporoland helminthosporic acid were not inhibited by BX-112, but thoseof GA5, GA9, GA15, GA19, GA20, GA31, GA44 and GA53 were inhibited.These results suggest that 3ß-hydroxylation is animportant and necessary step in the biosynthesis of gibberellinsthat promote shoot elongation in rice seedlings. The weak promotionof shoot elongation by GA22 in the presence of BX-112 suggeststhat the effect of a hydroxyl group at C-18 of GA22 might beable to mimic the effect of the 3ß-hydroxyl groupof GA1. Helminthosporol and helminthosporic acid may promotethe shoot elongation of rice by mimicking physiologically activegibberellins and not by stimulating their biosynthesis.
1Part I is the previous paper by Nakayama et al. (1990a)
3Present address: Frontier Research Program RIKEN, Wako-shi,Saitama, 351-01 Japan. (Received June 26, 1991; Accepted September 4, 1991) 相似文献
934.
U. Bornscheuer H. Stamatis A. Xenakis T. Yamane F. N. Kolisis 《Biotechnology letters》1994,16(7):697-702
Summary Four different approaches for the synthesis of monolaurylglycerol (MLG) by non specificPseudomonas cepacia lipase in a crude and purified form have been studied: a. The direct esterification of glycerol by lauric acid in bis-(2-ethylhexyl)sulfosuccinate
sodium salt (AOT)/isooctane microemulsion systems; b. the transesterification of glycerol by vinyl laurate in the presence
or not of any solvent; c. solid-phase glycerolysis of trilaurin; and, d. transesterification of protected glycerol, 1,2-O-isopropylidene
glycerol, by vinyl laurate, in the presence or not of any solvent. It was found that in the two latter cases (d and c) the
formation of pure MLG was occurred, while in the first two cases (a and b) apart of MLG the formation of DLG was also observed. 相似文献
935.
We examined that growth-promoting activity of two different human albumin (HSA) preparations for human diploid fibroblasts in serum-free RITC 80-7 medium. The activity of one preparation (sample A) was affected markedly by environmental oxygen, whereas the other (sample B) was little affected. Sample B contained ceruloplasmin (Cp) and haptoglobin (Hp) as impurities. To detect the generation of superoxide anion in the media the amount of reduction of cytochrome c that is inhibited by superoxide dismutase (SOD) was determined. In an aerobic environment it was relatively large in comparison with reduction inhibited in a hypoxic environment. Reduction in the sample A with HSA-supplemented medium was relatively large in comparison with that in sample B with HSA-supplemented medium. The reduction of cytochrome c also was inhibited by Cp (25 mg/l) and catalase (4000 units/ml). Moreover, SOD, Cp, catalase and Hp.Hb (but not Hp) partially prevented oxygen-dependent reduction in growth in an aerobic environment when added to sample A HSA-supplemented medium. These results suggest that Cp and Hp.Hb act as an antioxidants in culture. 相似文献
936.
937.
938.
Variation in the level of polyandry of females produces a difference in the risk of sperm competition among males. As a consequence,
investment in ejaculate expenditure by males should vary. We compared the number of sperm ejaculated by males into the female
reproductive organ of six strains of the adzuki bean beetle, Callosobruchus chinensis (Coleoptera: Bruchidae), when males were reared at different larval densities in a bean. A significant positive correlation
was found between the remating frequency of females and the ratio of the ejaculate sizes of high-density and low-density males
as a measure of the response to the risk of sperm competition among males. The measure was estimated by dividing the number
of sperm ejaculated by males reared at high larval density in a bean with the number of sperm ejaculated by males reared alone.
The number of sperm transferred by a male to a female was not correlated with the duration of copulation. The results suggest
an evolutionary relationship between ejaculatory expenditure and the level of polyandry in C. chinensis. 相似文献
939.
940.