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排序方式: 共有108条查询结果,搜索用时 15 毫秒
1.
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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Ivanov BN Sacksteder CA Kramer DM Edwards GE 《Archives of biochemistry and biophysics》2001,385(1):145-153
Chloroplasts in bundle sheath cells (BSC) of maize perform photosystem I (PSI)-mediated production of ATP. In this study, the participation of ascorbate (Asc) as an electron donor to PSI in light-induced electron transport in isolated maize BSC was demonstrated. It was found that Asc, at physiological concentrations, rapidly reduced photooxidized reaction center chlorophyll of PSI (P700). The rate of Asc donation of electrons to P700+ reached rates of 50-100 microequivalents (mg Chl)(-1) h(-1) at 70-80 mM ascorbate with methyl viologen as an electron acceptor. Electron transport supported by Asc was coupled with membrane energization, as demonstrated by the light-induced formation of a trans-thylakoid electric field measured by the electrochromic shift of carotenoids. The possible physiological function of Asc-dependent electron transport in bundle sheath chloroplasts of maize, as an electron donor for linear electron flow versus sustaining cyclic electron transport, is discussed. 相似文献
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Proton motive force (pmf), established across the thylakoid membrane by photosynthetic electron transfer, functions both to drive the synthesis of ATP and initiate processes that down-regulate photosynthesis. At the same time, excessively low lumen pH can lead to the destruction of some lumenal components and sensitization of the photosynthetic apparatus to photoinhibition. Therefore, in order to understand the energy budget of photosynthesis, its regulation and responses to environmental stresses, it is essential to know the magnitude of pmf, its distribution between pH and the electric field () as well as the relationships between these parameters and GATP, and down-regulatory and inhibitory processes. We review past estimates of lumen pH and propose a model that can explain much of the divergent data in the literature. In this model, in intact plants under permissive conditions, photosynthesis is regulated so that lumen pH remains mod erate (between 5.8 and 6.5), where it modulates the activity of the violaxanthin deepoxidase, does not significantly restrict the turnover of the cytochrome b6f complex, and does not destabilize the oxygen evolving complex. Only under stressed conditions, where light input exceeds the capacity of both photosynthesis and down-regulatory processes, does lumen pH decrease below 5, possibly contributing to photoinhibition. A value of n = 4 for the stoichiometry of protons pumped through the ATP synthase per ATP synthesized, and a minor contribution of to pmf, will allow moderate lumen pH to sustain the observed levels of GATP. 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