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1.
Transfer of N, N'-diacetylchitobiose from dolichyl diphosphate into a gray matter membrane glycoprotein 总被引:1,自引:0,他引:1
Gray matter and white matter membranes catalyze the transfer of label from UDP-N-acetyl-[] glucosamine into N-acetyl[]glucosaminyl-pyrophosphoryl-dolichol, N,N′-diacetyl []chitobiosyl-pyrophosphoryl-dolichol, and N-acetyl[]glucosamine-labeled glycoprotein. Gel filtration of the Pronase digests of gray matter N-acetyl[]glucosamine-labeled glycoprotein reveals two N-acetyl[]glucosamine-labeled glycopeptide fractions. One fraction (A) contains approximately eight glycose units. All of the radioactivity is at nonreducing termini and can be released by treatment with an exo-β-N-acetylglucosaminidase. A smaller N-acetyl[]glucosamine-labeled glycopeptide (B) is recovered in the elution volume expected for an asparaginyl disaccharide. Structural studies show that the labeled saccharide unit in glycopeptide B is N,N′-diacetyl[]chitobiose. The linkage between the -labeled disaccharide and the polypeptide has the properties of an N-glycosidic attachment to asparagine. Only the larger N-acetyl[]glucosamine-labeled glycopeptide (A) is found in Pronase digests of white matter membrane N-acetyl[]glucosamine-labeled glycoprotein after incubation with UDP-N-acetyl[]glucosamine. When gray matter membranes are incubated with UDP-N-acetyl[]glucosamine in the presence of tunicamycin or UMP, the labeling of glycolipid and the asparaginyl disaccharide is inhibited. UMP and tunicamycin have no effect on the transfer of N-acetyl[]glucosamine to external acceptor sites of the larger glycopeptide (A). The transfer of N,N′-diacetyl[]-chitobiose from carrier lipid to protein is observed when extensively washed membranes containing endogenous, prelabeled -labeled glycolipids are incubated in the presence or absence of unlabeled GDP-mannose. UMP treatment of the prelabeled membranes selectively discharged over 80% of the label from N-acetyl[]glucosaminyl-pyrophosphoryl-dolichol, but had no effect on the transfer of the -labeled disaccharide to protein. All of these results are concordant with transfer of N,N′-diacetylchitobiose from dolichyl diphosphate to gray matter glycoprotein. The major membrane glycoprotein labeled by the lipid-mediated []disaccharide transfer reaction has an apparent molecular weight of 24,000. Tunicamycin prevents the enzymatic labeling of the gray matter glycoprotein having an apparent molecular weight of 24,000. 相似文献
2.
A solution hybridization procedure for the rapid identification of M13 clones carrying a particular sequence is described. The method, which employs a radiolabeled oligonucleotide probe, can discriminate between sequences which differ by only a single base, and can therefore be used for the identification of mutant sequences created by oligonucleotide-directed mutagenesis. Samples of phage-containing supernatant from cultures of M13-infected Escherichia coli are incubated with radiolabeled probe in the presence of sodium dodecyl sulfate. The mixtures are then subjected to agarose gel electrophoresis to separate hybrid molecules from unbound probe and hybridization is detected by autoradiography. This solution hybridization procedure is quicker and more convenient than membrane hybridization and has the added advantage that more than one probe can be used on a given gel. 相似文献
3.
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
4.
A developmental change in dolichyl phosphate mannose synthase activity in pig brain 总被引:8,自引:3,他引:5
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The initial rate of dolichyl phosphate mannose biosynthesis was measured in white-matter membranes from pig brain at various ages from before birth throughout the period of most rapid brain development. Dolichyl phosphate mannose synthase activity increased from prenatal values to a maximum in 3 week-old animals, and gradually decreased to adult values after 8 weeks of age. The nature of the developmental change was investigated by enzymic and biochemical comparisons of the membrane preparations from the most active age (3 weeks) and adult controls. The specific activity of dolichyl phosphate mannose synthase in preparations from actively myelinating animals was approx. 3-fold higher than adults when mannolipid formation was assayed with saturating concentrations of GDP-[14C]mannose and utilizing only endogenous acceptor lipid. No major variations were found in the apparent Km values for GDP-mannose or exogenous dolichyl monophosphate. However, the ratio of dolichyl phosphate mannose synthase activity for myelinating animals/adult animals decreased significantly when large amounts of exogenous dolichyl monophosphate were added to the incubation mixtures. Dolichyl phosphate mannose synthase activity was also compared in white-matter membranes depleted of endogenous dolichyl monophosphate by enzymic mannosylation or treatment with butanol. When these preparations were assayed with identical amounts of exogenous dolichyl monophosphate, the dolichyl monophosphate-depleted membranes from actively myelinating animals contained only 20–30% more dolichyl phosphate mannose synthase activity. Overall, these studies strongly suggest that the developmental change in dolichyl phosphate mannose synthase activity is due primarily to the presence of a relatively lower amount of endogenous dolichyl monophosphate being accessible to the mannosyltransferase in the white-matter membranes from adult animals. 相似文献
5.
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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7.
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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