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Jerry R. Colca Nirmala Kotagal Paul E. Lacy Michael L. McDaniel 《生物化学与生物物理学报:生物膜》1983,729(2):176-184
The properties of active or ATP-dependent calcium transport by islet-cell endoplasmic reticulum and plasma membrane-enriched subcellular fractions were directly compared. These studies indicate that the active calcium transport systems of the two membranes are fundamentally distinct. In contrast to calcium uptake by the endoplasmic reticulum-enriched fraction, calcium uptake by islet-cell plasma membrane-enriched vesicles exhibited a different pH optimum, was not sustained by oxalate, and showed an approximate 30-fold greater affinity for ionized calcium. A similar difference in affinity for calcium was exhibited by the Ca2+-stimulated ATPase activities which are associated with these islet-cell subcellular fractions. Consistent with the effects of calmodulin on calcium transport, calmodulin stimulated Ca2+-ATPase in the plasma membranes, but did not increase calcium-stimulated ATPase activity in the endoplasmic reticulum membranes. The physiological significance of the differences observed in calcium transport by the endoplasmic reticulum and plasma membrane fractions relative to the regulation of insulin secretion by the islets of Langerhans is discussed. 相似文献
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A new medium containing sodium tripolyphosphate, ethylenediaminetetraacetic acid disodium salt, dihydrate, sodium desoxycholate, supplemented with minerals and nutrient sources was developed, which was very effective in inhibiting swarming of Bacillus spp. This medium polyphosphate-EDTA-desoxycholate agar (PEDA) was compared with tryptone glucose extract agar (Oxoid) for determining the total plate count of various semi-conserved fishery products. While promoting discrete colony formation of Bacillus spp., PEDA provided good bacterial recovery. PEDA is recommended for isolation or enumeration of bacteria in food dominated by swarming Bacillus spp. 相似文献
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Using well-established techniques, samples were obtained of the volatile essential oils of the two types of curry leaf, Murraya koenigii and Pandanus latifolius. Both contained mainly terpenes, and M. koenigii produced less than 4% of other components with eight monoterpene hydrocarbons (ca 16%) and 17 sesquiterpene hydrocarbons (ca 80%) being obtained. The most important constituents of M. koenigii are β-caryophyllene, β-gurjunene, β-elemene, β-phellandrene and β-thujene. The volatile essential oil of P. latifolius also contained mainly sesquiterpene hydrocarbons (6–42%) but the only monoterpene was linalool (ca 6%). Nearly 2000 times the total quantity of aroma volatiles was produced by M. koenigii compared with P. latifolius, and this partly explains the observed stronger flavour potency of the former. 相似文献
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Nirmala SundarRaj Judith Martin Nancy Hrinya 《Biochemical and biophysical research communications》1982,106(1):48-57
Hybridomas which secrete monoclonal antibodies against human type III procollagen have been developed. By an enzyme-linked immunosorbent assay, three of the monoclonal antibodies have been determined to be against non-helical extensions of the molecules while two of the antibodies are against helical portion of the molecules which is sensitive to bacterial collagenase action. These findings have been further confirmed by carrying out immuno-reaction of the pro α-chains transferred on nitrocellulose paper from sodium dodecyl sulfate polyacrylamide gels. These monoclonal antibodies have been found to be suitable reagents for immunohistochemical studies as well as for immunoassays of type III procollagen and collagen. 相似文献
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Methotrexate binds in a non-productive orientation to human dihydrofolate reductase in solution, based on NMR spectroscopy 总被引:1,自引:0,他引:1
B J Stockman N R Nirmala G Wagner T J Delcamp M T DeYarman J H Freisheim 《FEBS letters》1991,283(2):267-269
Dihydrofolate reductase (DHFR) is an intracellular target enzyme for folate antagonist drugs, including methotrexate. In order to compare the binding of methotrexate to human DHFR in solution with that observed in the crystalline state, NMR spectroscopy has been used to determine the conformation of the drug bound to human DHFR in solution. In agreement with what has been observed in the crystalline state, NOE's identified protein and methotrexate protons indicate that methotrexate binds in a non-productive orientation. In contrast to what has been reported for E. coli DHFR in solution, only one bound conformation of methotrexate is observed. 相似文献
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In the progeny after selfing of a normally open pollinated variety (L.S. 326-3) of pearl millet (Pennisetum americanum (L.) Leeke, n=7) one plant exhibited desynapsis, chromosome stickiness and high sterility. Meiosis was normal until diplotene. Thereafter, it was characterized by dissociation of bivalents into univalents and formation of nonspecific congregations of chromosomes at diakinesis, shrinkage of cytoplasm and occurrence of unoriented sticky chromatin masses at metaphase I, relaxation of stickiness, unbalanced chromosome numbers at the poles and laggards at anaphase I, and presence of other irregularities in subsequent stages. Meiosis was completed. Male and female sterility was high. This meiotic mutant thus has multiple effects and is inherited as a monogenic recessive and designated as st. 相似文献
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Mutations in the fumarate hydratase gene cause hereditary leiomyomatosis and renal cell cancer in families in North America 总被引:10,自引:0,他引:10
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Toro JR Nickerson ML Wei MH Warren MB Glenn GM Turner ML Stewart L Duray P Tourre O Sharma N Choyke P Stratton P Merino M Walther MM Linehan WM Schmidt LS Zbar B 《American journal of human genetics》2003,73(1):95-106
Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an autosomal dominant disorder characterized by smooth-muscle tumors of the skin and uterus and/or renal cancer. Although the identification of germline mutations in the fumarate hydratase (FH) gene in European families supports it as the susceptibility gene for HLRCC, its role in families in North America has not been studied. We screened for germline mutations in FH in 35 families with cutaneous leiomyomas. Sequence analysis revealed mutations in FH in 31 families (89%). Twenty different mutations in FH were identified, of which 18 were novel. Of these 20 mutations, 2 were insertions, 5 were small deletions that caused frameshifts leading to premature truncation of the protein, and 13 were missense mutations. Eleven unrelated families shared a common mutation: R190H. Eighty-one individuals (47 women and 34 men) had cutaneous leiomyomas. Ninety-eight percent (46/47) of women with cutaneous leiomyomas also had uterine leiomyomas. Eighty-nine percent (41/46) of women with cutaneous and uterine leiomyomas had a total hysterectomy, 44% at age < or =30 years. We identified 13 individuals in 5 families with unilateral and solitary renal tumors. Seven individuals from four families had papillary type II renal cell carcinoma, and another individual from one of these families had collecting duct carcinoma of the kidney. The present study shows that mutations in FH are associated with HLRCC in North America. HLRCC is associated with clinically significant uterine fibroids and aggressive renal tumors. The present study also expands the histologic spectrum of renal tumors and FH mutations associated with HLRCC. 相似文献
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