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51.
An antiserum to glutathione S-transferase (EC 2.5.1.18) from maize (Zea mays L.) responsible for herbicide detoxification has been raised in rabbit. The antiserum was specific to the Mr 26000 subunit of the enzyme from maize seedlings and suspension-cultured cells, and recognized the isoenzymes active toward both atrazine and metolachlor. When plants were treated for 24 h with the herbicide antidote N,N-diallyl-2-2-dich-loroacetamide (DDCA), enzyme activities toward metolachlor were doubled in the roots and this was associated with a 70% increase in immunodetectable protein. Translation of polysomal RNA in vitro showed that the increase in the transferase in root tissue was brought about by a ninefold increase in mRNA activity encoding the enzyme. Treatment of suspension-cultured cells with cinnamic acid, metolachlor and DDCA raised enzyme activities but did not increase synthesis of glutathione S-transferase. In cultured maize cells, enzyme synthesis was maximal in mid-logarithmic phase, coinciding with the highest levels of enzyme activity. When callus cultures were established from the shoots of a maize line known to conjugate chloro-s-triazines, enzyme activity towards atrazine was lost during primary dedifferentiation. However, levels of total immunodetectable enzyme and activity toward metolachlor were increased in cultured cells compared with the parent shoot tissue. 相似文献
52.
Though the physiological role of specific binding proteins in serum is unknown, and the validity of the "free hormone hypothesis" has been challenged by several authors (including ourselves), we regard Pardridge's widely publicised objections to this hypothesis (and his recent suggestion of the existence of complex biochemical mechanisms causing the release of individual hormones in particular tissues) as deriving from an incorrect analysis of the effects of serum binding proteins on the kinetics of hormone transport, and therefore without foundation. This presentation is intended to substantiate this view. 相似文献
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The electrochemical properties of three nitroimidazoles, a nitropyrazole, a nitrofuran and three nitroben-zenoid compounds have been extensively investigated in a range of solvents. The reduction pathway for the nitro group is independent of the cyclic function to which it is attached, but is strongly influenced by the nature of the solvent. In aqueous media, generally, a single, irreversible 4-electron reduction occurs to give the hydroxylamine. In aprotic media (dimethylformamide, methylene chloride or dimethylsulphoxide), a reversible one-electron reduction takes place to form a stable nitro radical anion. At more negative values, a further 3-electron reduction occurs, irreversibly to give the hydroxylamine. In mixed aqueous-organic systems, intermediate behaviour is found, with the reversibility of the RNO2/RNO2- couple increasing with addition of organic medium. The control of the reduction pathway, by changing the electrolytic medium is discussed in relation to the biological activities of the drugs and identification of the short-lived reduction intermediate responsible for DNA damage. 相似文献
55.
Homosexual mounting in apes and prosimians is rare. Male-male mounting was observed between an adult male white-handed gibbon
and an adolescent male in the same group. The behaviour is discussed in terms of the gibbon group's social structure and the
development of the adolescent. It is suggested that this behaviour provides reassurance for the adolescent gibbon. 相似文献
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Pea lectin is correctly processed,stable and active in leaves of transgenic potato plants 总被引:5,自引:0,他引:5
Glyn A. Edwards Andrew Hepher Stephen P. Clerk Donald Boulter 《Plant molecular biology》1991,17(1):89-100
A gene encoding the preproprotein of the pea (Pisum sativum) lectin was expressed in transgenic potato plants using a cauliflower mosaic virus (CaMV) 35S promoter or a tobacco ribulose bisphosphate carboxylase small subunit (ssRubisco) promoter. Presence of the pea lectin to levels greater than 1% of total soluble leaf protein was detected by radioimmunoassay (RIA). The pattern of expression derived from the two promoters was established using both RIA and a squash-blot immunolocalisation technique. Western blotting demonstrated that the preproprotein was correctly processed, generating and subunits that assembled to give an isolectin form observed in pea seeds and roots. It was also found that the haemagglutination activity and specificity of pea lectin synthesised in transgenic potato leaves was comparable to purified lectin from pea cotyledons. 相似文献
58.
Body size plays an important role in the outcome of aggressive encounters between males of the symbiotic freshwater miteUnionicola formosa. Since intruding males displace resident males as often as resident males successfully defend their territory (mantle cavity of a mussel), resident males do not hold a competitive advantage during male-male aggressive encounters. Larger male size probably enhances a male's success when competing for receptive females. 相似文献
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