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1.
Mutants of Arabidopsis thaliana L. (Heynh), characterized asdeficient in their freezing tolerance after cold acclimation,were surveyed for some of the normal responses to cold exposure.In foliar tissue, the coldinducibility of three proteins, thelevels of sucrose and glucose, the fatty acyl composition oflipids, and the accumulation of anthocyanin was examined. Fourmutations (sfr3, sfr4, sfr6, and sfr7) reduced or eliminatedthe accumulation of anthocyanin during cold acclimation. Onemutation (sfr4) prevented the normally cold-induced elevationof sucrose and glucose levels; both sfr4 and another mutation(sfr7) affected fatty acid composition after (and only after)cold acclimation. On the other hand mutations sfr1, sfr2 andsfr5 did not differ significantly from the wild type in anyof the parameters tested, suggesting that they have other, perhapshighly specific, effects on lowtemperature responses. Key words: Arabidopsis thaliana, cold acclimation, freezing tolerance, mutation 相似文献
2.
Seed transmission of turnip yellow mosaic virus in winter turnip and winter oilseed rapes 总被引:1,自引:0,他引:1
This is the first record of seed transmission of turnip yellow mosaic virus (TYMV) in oilseed and turnip rapes. The seed transmission of TYMV in a naturally infected winter turnip rape (Brassica napus var. silvestris) cultivar Perko PVH was investigated. By ELISA 1.6%, 3.2% and 8.3% seed transmission of the virus was found in seed of plants from three localities. The proportion of infected seeds produced by artificially infected plants of winter oilseed rape (Brassica napus ssp. oleifera) and winter turnip rape cultivars was determined. The virus transmission rate, expressed as the proportion of virus-infected plants which germinated from the seed was for the oilseed rape cvs Jet Neuf 0.1%, Solida 0.4%, Silesia 0.8%, Darmor 1.2%, SL-507 0.2%, SL-509 0.0% and for the winter turnip rape cv. Perko 1.5%. ELISA cannot be used in direct tests on bulk seed lots to estimate proportion of infected seed, but must be used on germinated seedlings. 相似文献
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TERESA MARYAKA HALSZKA OSMÓLSKA 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1979,12(3):265-273
Supraorbital bones in Saurolophus angustirostris are described, and their presence in all hadrosaurs is suggested. Frontal-nasal and premaxillar-nasal fontanellae are distinguished in hadrosaurs; their presence is explained as connected with growth and considered to he responsible for the variability of crest structures. New data indicating the presence of a cartilaginous diverticulum nasi within the circumnarial depression in Saurobphus ongustirostris are presented. A physiological (respiratory and/or thermoregulatory) function of the nasal diverticulum is proposed. 相似文献
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The paper presents multiplex panels of polymorphic microsatellites for two closely related cryptic species Pipistrellus pipistrellus and Pipistrellus pygmaeus. We tested the cross‐species amplification of 34 microsatellite loci, originally developed for five vespertilionid bat species. Ten and nine polymorphic loci in P. pipistrellus (mean number of alleles per locus = 10.5) and P. pygmaeus (8.1), respectively, in three multiplex polymerase chain reactions per species were amplified. All loci can be analysed in a single fragment analysis and can be used as markers to the study of evolution and the ecology of structured populations of socially living bats. 相似文献
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J?Craig CohenEmail author Lennart?KA?Lundblad Jason?HT?Bates Michael?Levitzky Janet?E?Larson 《BMC genetics》2004,5(1):21
Background
Cystic Fibrosis is a pleiotropic disease in humans with primary morbidity and mortality associated with a lung disease phenotype. However, knockout in the mouse of cftr, the gene whose mutant alleles are responsible for cystic fibrosis, has previously failed to produce a readily, quantifiable lung phenotype. 相似文献10.
Previous work has demonstrated that the ferric form of soybean lipoxygenase-1 will catalyze an elimination reaction on 12-iodo-cis-9-octadecenoic acid (12-IODE) to produce 9, 11-octadecadienoic acid and iodide ion. Elimination is accompanied by irreversible inactivation of the enzyme on 1 out of 10 turnovers. In the present work, 11,11-dideuterio-12-IODE (D(2)-12-IODE) was synthesized and used to demonstrate that both the elimination reaction and inactivation of the enzyme exhibit very large kinetic isotope effects. The rates with the deuterated compound are so low that the isotope effects are difficult to quantify, but they appear to be comparable to the isotope effects previously observed for the normal reaction catalyzed by lipoxygenase and much larger than can be explained by zero-point energy considerations. ESR spectroscopy was used to demonstrate that 12-IODE can reduce ferric lipoxygenase to the ferrous form, and a large isotope effect on this process was observed with D(2)-12-IODE. It is proposed that the pathway leading to reduction and inactivation by 12-IODE is initiated by homolytic cleavage of the C(11)-H bond. Elimination could be initiated either by homolytic or by heterolytic cleavage of this bond. The results suggest that very large isotope effects may be a general feature of C-H bond cleavages catalyzed by this enzyme. 相似文献