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81.
J L Nieva J Castresana A Alonso 《Biochemical and biophysical research communications》1990,168(3):987-992
The steady-state anisotropy of trimethylammonium diphenylhexatriene fluorescence has been used to monitor the thermotropic lamellar to HII hexagonal phase transition in an unsaturated phosphatidylethanolamine. The transition is observed in lipid aggregates when they are heated above the transition temperature Th, as well as in diluted liposomes after aggregation above Th. Changes in fluorescence anisotropy are not observed with Ca(++)-induced fusion of phosphatidylserine vesicles, a process not involving hexagonal phase formation. 相似文献
82.
Cesar Cardona Julia Kornegay Carmen E. Posso Francisco Morales Hernando Ramirez 《Entomologia Experimentalis et Applicata》1990,56(2):197-206
Wild Phaseolus vulgaris L. accessions containing arcelin codominant alleles 1 through 5 were reconfirmed and characterized for resistance to the Mexican bean weevil, Zabrotes subfasciatus (Boheman) (Coleoptera: Bruchidae). Accession G 02771 (arcelin 5) had the highest level of antibiosis resistance, followed by G 12952 (arcelin 4), G 12882 (arcelin 1) and G 12866 (arcelin 2). Arcelin 3 accessions conferred the lowest levels of resistance. As the presence of arcelin is inherited as a single dominant gene, a backcross breeding program has been used to transfer resistance to the Mexican bean weevil from wild beans to bean cultivars using serological techniques to detect the presence of arcelin and replicated insect feeding tests to measure resistance levels. Progeny containing arcelin 1 showed resistance equal or superior to that of the resistant check. Arcelin 2-deerived lines had intermediate levels of resistance while no resistant progenies were obtained from crosses with arcelin 3 and 4 sources. Results are discussed in relation to the deployment of arcelin alleles in bean cultivars.
Valeurs comparées de 5 types d'arcéline dans l'obtention de lignées de Phaseolus vulgaris résistantes à Zabrotes subfasciatus
Résumé La résistance à Zabrotes subfasciatus est associée à la présence d'arcéline, une nouvelle protéine des graines, découverte chez quelques populations de Phaseolus vulgaris. 5 types d'arcéline, hérités comme allèles codominants ont été décrits dans la littérature. Nous avons reprécisé les différentes populations contenant différents types d'arcéline et caractérisé leurs résistances à Z. subfasciatus. La population G 02771, correspondant à l'arcéline 5, présente la résistance la plus élevée par antibiose, suivie de G 12952 (arcéline 4), G 12882 (arcéline 1) et G 12866 (arcéline 2). Les populations contenant l'arcéline 3 présentent le moins de résistance à Z. subfasciatus.Un programme de croisements en retour associé à des tests sérologiques pour déceler la présence d'arcéline chez les descendants jeunes et des expériences répétées d'alimentation par les insectes vec BC2F3 a été réalisé pour transférer la résistance de populations naturelles à des cultivars de haricots. Les lignées, provenant de croisements avec des populations sauvages avec de l'arcéline 1, ont été fortement résistantes à Z. subfasciatus. Les lignées contenant de l'arcéline 2 ont été considérées comme ayant une résistance intermédiaire. Les lignées avec arcélines 3 et 4 étaient sensibles. Les raisons de l'échec du transfert de la résistance élevée des parents contenant de l'arcéline 4, sont inconnues. On a constaté que la concentration de l'arcéline dans les lignées contenant cet allèle était très faible, tandis que la concentration en arcéline 1 restait remarquablement élevée. Les recherches sont poursuivies pour déterminer les raisons de l'absence de transfert de l'arcéline 4 chez les descendants contenant cet allèle. Quoi qu'il en soit, les caractéristiques agronomiques et les qualités des lignées résistantes (codées RAZ) ont été évaluées en vue d'une diffusion pour les programmes nationaux de recherche des pays de basses altitudes intertropicaux ou Zabrotes subfasciatus fait des dégâts importants.相似文献
83.
84.
Reduction of the e-isoprene unit of polyprenols to form dolichols was studied in vivo using3H-polyprenol derivatives as substrates and liposomes as carriers. Liposomes containing labeled polyprenol, polyprenyl phosphate, or polyprenyl pyrophosphate were injected through the portal vein into the livers of rats under anesthesia. Uptake and conversion of the labeled compounds to dolichol derivatives was studied at different intervals. The greatest conversion to dolichol derivatives was found with polyprenyl pyrophosphate and polyprenyl monophosphate, with 31% and 8% of the absorbed dose converted respectively. Less than 0.2% of the absorbed polyprenol was converted to dolichol derivatives. These results suggest that the substrate for the -isoprene reductase involved in dolichol biosynthesis is either polyprenyl monophosphate or polyprenyl pyrophosphate, or both. 相似文献
85.
M.Carmen Aragón Cecilio Giménez Federico Mayor Juan G. Marvizón Fernando Valdivieso 《生物化学与生物物理学报:生物膜》1981,646(3):465-470
Tyrosine uptake by membrane vesicles derived from rat brain has been investigated. The uptake is dependent on an Na+ gradient ([). The uptake is transport into an osmotically active space and not a binding artifact as indicated by the effect of increasing the medium osmolarity. The process is stimulated by a membrane potential (negative inside) as demonstrated by the effect of the ionophores valinomycin and carbonyl cyanide and anions with different permeabilities. Kinetic data show that tyrosine is accumulated by two systems with different affinities. Tyrosine uptake is inhibited by the presence of phenylalanine and tryptophan. 相似文献
86.
87.
John Vasiliades Tuomah M. Sahawneh Carmen Owens 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1979,164(4):457-470
A gas—liquid chromatographic procedure is presented for the determination of therapeutic and toxic serum levels of doxepin and loxapine, using a nitrogen—phosphorus-sensitive detector. Amitriptyline is used as the internal standard. The method is accurate, sensitive and specific with no derivatization required prior to analysis. An advantage of the procedure is the small serum sample size needed for analysis and the selectivity and sensitivity of the detector, with the limit of detection being 3 and 2 μg/l for doxepin and loxapine, respectively. Nine cases of doxepin and loxapine misuse are presented. Serum doxepin concentrations ranged from 113 to 439 μg/l, with a loxapine concentration of 192 μg/l observed in one patient. The presence of the tricyclics was identified and confirmed by gas chromatography—mass spectrometry and the mass spectrum of loxapine is reported. 相似文献
88.
89.
Carmen Attolini Giorgio Mazza Adriana Fortunato Giovanni Ciarrocchi Giorgio Mastromei Silvano Riva Arturo Falaschi 《Molecular & general genetics : MGG》1976,148(1):9-17
Summary The dnaP strains of Bacillus subtilis are altered in the initiation of DNA replication at high temperature (Riva et al., 1975). Fine mapping of the gene shows that it is located very close to the dnaF gene, described by Karamata and Gross (1970) and mapped by Love et al. (1976) in the polC region. The phenotype of both mutants is indistinguishable: the DNA synthesis stops at non permissive temperature after synthesizing an amount of DNA equivalent to the completion of the rounds of replication already initiated; at permissive temperature they are abnormally sensitive to MMS and are reduced in the ability to be transformed. Both mutants are to be considered as belonging to the dnaF locus.The dnaF gene is very close to the polC gene, which specifies the DNA polymerase III of B. subtilis. The DNA polymerase III of the dnaF mutants is not temperature sensitive in vitro, however, the level of this enzyme is lower by a factor of 4 or 5 in the dnaF mutants, at the permissive temperature. Following shift of dnaF cultures to the non permissive temperature, the level of DNA polymerase III activity specifically decreases further by a factor of at least 10 in the mutant, whereas the DNA polymerase I level is unaffected.The possible roles of the dnaF gene in the control of the cellular level of the DNA polymerase III, and the possibility of a regulatory role of DNA polymerase III in the initiation of DNA replication in bacteria are discussed.Abbreviations and symbols HPUra
6-(p-hydroxyphenylazo)-uracil; mic, minimum inhibitory concentration
- MMS
methyl-methanesufonate
- Pol I
Pol II and Pol III: DNA polymerase I, II and III respectively
- PCMB
parachloro-mercuri-benzoate 相似文献
90.
Summary The dryness-induced ultrastructural changes of both myco- and phycobiont of three lichen species (R. geographicum, P. conspersa, andU. pustulata) have been studied over three months and half, period of time. During this time other ecological factors, such as rock substratum, temperature, light and gas interchange were unaltered compared to the natural conditions. A large number of ultrastructural changes were observed in the mycobiont as well as in the phycobiont (Trebouxia) and often, cells showed a highly disorganized morphology. The most important ultrastructural modifications were: 1. pyrenoglobuli of the algae were peripheral, 2. new and unknown structures were observed in the phycobionts of bothR. geographicum andU. pustulata as well as in the mycobiont of the latter species. 相似文献