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1.
2.
A gene encoding the endogenous superantigen Mlsc, which deletes Tcrb-V3+ T cells in the NOD inbred mouse strain, was found to co-segregate with Mtv-3 on chromosome 11. This identifies a fourth gene encoding a deletion ligand for Tcrb-V3+ T cells and extends recently published observations in support of the hypothesis that a number of endogenous superantigens are the products of Mtv proviruses.
Address correspondence and offprint requests to : K. Tomonari. 相似文献
3.
A total of 34 isolates ofListeria monocytogenes were tested against ampicillin, cephalothin, chloramphenicol, erythromycin, tetracycline, and penicillin-G using the Autobac 3-h AIS and the Autobac 5-h MIC procedures. The results were compared to susceptibility category interpretations and MICs determined using the Sceptor system. With the Sceptor System, all isolates were interpreted to be moderately susceptible to ampicillin and penicillin-G, and susceptible to the four other antibiotics. With the Autobac AIS, all isolates were interpreted to be susceptible to all the antibiotics except penicillin-G. All but one of the 34 isolates were interpreted to be resistant to penicillin-G with the Autobac AIS test. The remaining isolate was interpreted to be indeterminant. The Autobac AIS test was unsatisfactory for determining the susceptibility ofL. monocytogenes isolates to penicillin-G. The Autobac MIC results correlated well with the MIC results of the Sceptor system provided that the Autobac was programmed as though it were testing enterococci. The Autobac MIC reported penicillin-G MICs in units per milliliter and required the use of a conversion factor to obtain micrograms per milliliter, and did not allow for the testing of erythromycin. The Autobac MIC susceptibility category interpretations must not be used, as they were derived from an outdated susceptibility standard. The Autobac MIC test may be used if the limitations given above are observed. 相似文献
4.
Isolation of single taste cells from lingual epithelium 总被引:1,自引:0,他引:1
A method is described for obtaining large numbers of isolatedtaste cells with identified polarity from lingual epithelium.The procedure involves incubating lingual epithelium in collagenase,staining the apical surface with fluorescein-conjugated wheatgerm agglutinin (FTTC-WGA), peeling non-gustatory surface epitheliumfrom the underlying taste buds and connective tissue, and dissociatingisolated taste buds with Ca2+-free saline. Isolated taste cellsretain their characteristic morphology for at least 30 min afterdissociation, and the apical specialization can be identifiedas a single patch of fluorescence usually located at the tipof an elongate process. Isolated taste cells are amenable tostudy with the patch-clamp technique, and whole-cell patch-clamprecordings show that isolated taste cells have membrane propertiessimilar to taste cells of intact lingual epithelium. Evidenceis presented that FITC-WGA staining does not alter the voltage-dependentionic currents of the taste cell membrane. 相似文献
5.
H Y Ahn L F Sue J K Ma C A Pinkstaff R S Pore D O Overman C J Malanga 《Biochimica et biophysica acta》1988,966(1):122-132
The ability of the isolated gill epithelium of Mytilus edulis to incorporate [14C]glucosamine as a precursor in the biosynthesis and secretion of mucous glycoproteins was investigated. Localization of mucous cells in the gill filament was achieved using histochemical staining techniques. Mucus cells containing neutral and acidic mucins were found in the lateral region, whereas mucus cells containing primarily neutral or sulfated mucins were found in the abfrontal region. Autoradiographic results showed that in both regions, the mucous cells were rich in content of the incorporated radiolabel. The secreted glycoproteins containing the incorporated radiolabel were analyzed by column chromatography using Bio-Gel P-2 and P-6. Two populations of the glycoproteins differing in molecular size were isolated. Upon alkaline reductive borohydride cleavage of the O-glycosidic linkages of the high molecular weight protein, about 70% of the radiolabel and 85% of the carbohydrate content were removed from the protein. The alkaline borohydride cleavage resulted in the formation of at least six oligosaccharide chains of various lengths of sugar units. Gas chromatographic analysis of the carbohydrate composition shows that the glycoproteins contain N-acetylglucosamine, N-acetylgalactosamine, and galactose, fucose, and mannose as the neutral monosaccharides. The above results indicate that the isolated gill epithelium of M. edulis is capable of incorporating [14C]glucosamine in the synthesis of secretable mucin-type glycoproteins. 相似文献
6.
Summary The most widely used technique of leaf water potential measurements is with the Scholander pressure chamber. Representative leaf water potential values require many determinations on individual leaves and this can be time consuming in large fields or experiments with multiple treatments. This paper describes a method of obtaining a mean value more rapidly, by using two leaves in the pressure chamber at the same time, but recording the end point of each leaf separately. 相似文献
7.
Yvonne H. Edwards Sue Povey Kay M. Levan Catherine E. Driscoll Jose Luis Millan Erwin Goldberg 《Genesis (New York, N.Y. : 2000)》1987,8(4):219-232
From the data presented in this report, the human LDHC gene locus is assigned to chromosome 11. Three genes determine lactate dehydrogenase (LDH) in man. LDHA and LDHB are expressed in most somatic tissues, while expression of LDHC is confined to the germinal epithelium of the testes. A human LDHC cDNA clone was used as a probe to analyze genomic DNA from rodent/human somatic cell hybrids. The pattern of bands with LDHC hybridization is easily distinguished from the pattern detected by LDHA hybridization, and the LDHC probe is specific for testis mRNA. The structural gene LDHA has been previously assigned to human chromosome 11, while LDHB maps to chromosome 12. Studies of pigeon LDH have shown tight linkage between LDHB and LDHC leading to the expectation that these genes would be syntenic in man. However, the data presented in this paper show conclusively that LDHC is syntenic with LDHA on human chromosome 11. The terminology for LDH genes LDHA, LDHB, and LDHC is equivalent to Ldhl, Ldh2, and Ldh3, respectively. 相似文献
8.
Mary Taub Milton H. Saier Lorraine Chuman Sue Hiller 《Journal of cellular physiology》1983,114(2):153-161
Prostaglandin E1(PGE1), one of the components in the hormone-supplemented, serum-free medium for Madin Darby Canine Kidney (MDCK) cells (Medium K-1), is required for both long-term growth and for dome formation. Variant cells have been isolated from MDCK populations, which lack the PGE1, requirement for long-term growth in Medium K-1. These variants will be useful in identifying the molecular events initiated by PGE1 which are necessary for the growth response to be observed. The growth and functional properties of five independently isolated PGE1 independent clones have been examined. Normal MDCK cells grew at an equivalent rate in Medium K-1 and in serum-supplemented medium; the growth rate was lower in Medium K-1 lacking PGE1. In contrast, PGE1 independent clone 1 grew at an equivalent rate in Medium K-1 minus PGE1, and in serum-supplemented medium. When PGE1 was added to K-1 minus PGE1, less growth of PGE1 independent clone 1 was observed. A similar observation was made with one other PGE1 independent clone which was studied. A hormone deletion study indicated that PGE1 independent clone 1 still retained growth responses to the other four supplements in Medium K-1 (insulin, transferrin, T3, and hydrocortisone). The molecular alterations associated with loss of the PGE1 requirement for long-term growth were examined. At confluency, all of the PGE1 independent clones studied had higher intracellular cyclic AMP levels following PGE1 treatment, as compared with normal MDCK cells. The increased cyclic AMP levels in the variant cells could result from a number of different types of defects, including reduced cyclic adenylic acid (cyclic AMP) efflux, an increased affinity of PGE2 for the PGE1 receptor, or a defect in cyclic AMP metabolism. However, in all of the variant clones studied a decreased rate of cyclic AMP degradation by cyclic AMP phosphodiesterase was observed. Thus, the increased cyclic AMP levels in the PGE1 independent variants may result from alterations which affect cyclic AMP metabolism. The effect of PGE1 on dome formation by the variant cells was also examined. The frequency of dome formation by PGE1 independent clone 1 was enhanced in a dosage-dependent manner, like normal MDCK cells. This observation suggests that PGE1 affects MDCK cell growth and dome formation by different mechanisms. 相似文献
9.
Summary A comparative study was made of the ultrastructure, distribution and abundance of leaf microbodies in four species of temperate grasses with high and four tropical grasses with low CO2-photorespiration. The temperate grasses were all festucoid; the tropical grasses included two panicoid species and two chloridoid. Comparisons of relative abundance were made by computing the average numbers of microbody profiles per cell section.Although microbodies were present in the green parenchymatous leaf cells in all grasses examined, their average number per cell was in general severalfold greater in the grasses with high CO2-photorespiration than in those with low. Furthermore, whereas in the grasses with high CO2-photorespiration the microbodies were distributed through the mesophyll, in those with low CO2-photorespiration they were concentrated in the vascular-bundle-sheath cells and were smaller and relatively scarce in the mesophyll cells. The leaf microbodies of the eight grass species resembled one another in general morphology, but differed to some extent in regard to size and type of inclusion. Microbodies of all four festucoid species contained numerous fibrils with a discernible substructure. Those of the two panicoid species contained clusters of round bodies with transparent cores. The equivalence of the microbodies to peroxisomes as biochemically defined was shown cytochemically by employing 3,3-diaminobenzidine for the localization of catalase, a marker enzyme for the peroxisome. This reaction was blocked by the catalase inhibitor, aminotriazole.The observations on the relative abundance and distribution of peroxisomes in leaves of grasses with high CO2-photorespiration versus those with low are consistent with the published biochemical data on the levels and distribution of peroxisomal enzymes in representatives of plants with high and low CO2-photorespiration, and may help explain the differences in apparent photorespiratory levels between these two groups of plants. 相似文献
10.