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1.
The microbial degradation of morpholine 总被引:5,自引:1,他引:4
Morpholine can be completely degraded microbiologically, and two organisms have been isolated, each capable of growth in a simple mineral salts medium with morpholine as the sole source of carbon, nitrogen and energy. Excess nitrogen is liberated as ammonia. The enzymes responsible for the oxidation of morpholine are inducible and, in organism Mor G, will also oxidize piperidine, piperazine and pyrrolidine, which are not growth substrates. Ethanolamine is a likely intermediate, though the metabolic steps in morpholine degradation do not give rise solely to acetyl-CoA. After a period of acclimation, a laboratory scale activated sludge plant effectively removed morpholine over the long period it was operated; the sludge was also capable of nitrification. The possible effects of other chemicals in trade wastes containing morpholine on nitrification and morpholine oxidation are described. 相似文献
2.
Regulation of the CD2 alternate pathway of T cell activation by CD3. Evidence for heterologous desensitization 总被引:2,自引:0,他引:2
W Holter O Majdic H Stockinger B H Howard W Knapp 《Journal of immunology (Baltimore, Md. : 1950)》1988,140(4):1043-1046
Normal resting T cells were stimulated through the alternate CD2 pathway. A CD3 mAb VIT3 completely blocked their proliferative response. The time interval for 50% inhibition lasted for 24 h after the onset of CD2 stimulation. Mitogen-activated cloned long term cultured T cells could also be stimulated via CD2. This proliferative response was again inhibitable by VIT3, indicating that CD3 regulates the CD2 pathway not only in resting cells, but also in lymphocytes actively involved in an Ir. T cells were further loaded with Quin2 and their free cytoplasmic Ca2+ levels were monitored in response to CD3 and CD2 stimulation. Antibodies directed against both surface R triggered a rapid elevation of Ca2+ levels. Both responses were abrogated when the cells had been treated overnight with VIT3. The free cytoplasmic Ca2+ levels of VIT3-pretreated cells, however, were not higher than those of control cells. These results point to a functional interaction between CD3 and CD2 possibly at the level of signal transducing proteins. Finally, cholera toxin was found to inhibit the Ca2+ response in Jurkat T cells. Both the CD3 and CD2 stimulation were sensitive to cholera toxin, indicating that a GTP-binding protein may be involved in signal transduction for both surface structures. 相似文献
3.
4.
Sandra Knapp 《Brittonia》1986,38(1):89-91
Solanum malacothrix S. Knapp is described from the slopes of the Sierra Madre del Sur in the Río Balsas drainage in the state of Guerrero. It is apparently rare, and has been collected only twice. Its relationship to other species in Mexico and northern South America is discussed. 相似文献
5.
Trimethyloxonium modification of single batrachotoxin-activated sodium channels in planar bilayers. Changes in unit conductance and in block by saxitoxin and calcium 总被引:13,自引:9,他引:4 下载免费PDF全文
Single batrachotoxin-activated sodium channels from rat brain were modified by trimethyloxonium (TMO) after incorporation in planar lipid bilayers. TMO modification eliminated saxitoxin (STX) sensitivity, reduced the single channel conductance by 37%, and reduced calcium block of inward sodium currents. These effects always occurred concomitantly, in an all-or-none fashion. Calcium and STX protected sodium channels from TMO modification with potencies similar to their affinities for block. Calcium inhibited STX binding to rat brain membrane vesicles and relieved toxin block of channels in bilayers, apparently by competing with STX for the toxin binding site. These results suggest that toxins, permeant cations, and blocking cations can interact with a common site on the sodium channel near the extracellular surface. It is likely that permeant cations transiently bind to this superficial site, as the first of several steps in passing inward through the channel. 相似文献
6.
G Steiner E Tschachler M Tani T R Malek E M Shevach W Holter W Knapp K Wolff G Stingl 《Journal of immunology (Baltimore, Md. : 1950)》1986,137(1):155-159
Rat monoclonal antibodies 3C7 and 7D4 detect two distinct functional regions of the murine interleukin 2 (IL 2) receptor. When studying the emergence kinetics of IL 2 receptors in mixed epidermal cell (EC)-lymphocyte cultures by using 3C7 and 7D4 in an indirect immunofluorescence assay, we regularly encountered a distinctive membrane fluorescence not only on lymphocytes, but also on a subpopulation of cells exhibiting a dendritic morphology. Reasoning that these 3C7/7D4-reactive dendritic cells might represent a subpopulation of epidermal dendritic cells, we studied mouse EC for the presence of 3C7/7D4- reactive cells. Although 3C7/7D4 reactivity was never detected on freshly isolated EC or on epidermal sheets, a small number of 3C7/7D4+ cells was encountered after 24 to 48 hr of culture. These cells exhibited a dendritic shape, expressed Ia antigens, lacked Thy-1 antigens, and displayed the ultrastructural features of Langerhans cells (LC) with the notable exception of Birbeck granules. Although after 24 hr, only 20% of Ia+ EC were 3C7/7D4+, the vast majority of LC displayed 3C7/7D4 binding sites after 4 to 5 days of culture. Preincubation of cultured LC-enriched EC with recombinant human IL 2 prevented subsequent 3C7-but not 7D4-binding to these cells. Western blot analysis of 7D4-reactive material of detergent extracts from LC-enriched EC revealed three bands in the same m.w. range as reported for CTLL cells. These results demonstrate that cultured LC express IL 2 receptors and may bear important implications for a better understanding of growth regulation, differentiation, and immunologic functions of LC. 相似文献
7.
Kinetics of activation antigen expression by in vitro-stimulated human T lymphocytes 总被引:5,自引:0,他引:5
In this study a panel of monoclonal antibodies was used to investigate the kinetics of the appearance of activation-linked surface determinants as well as cytoplasmic and nuclear determinants in human T cells following lectin stimulation. Well known activation markers, such as Ia/DR, transferrin receptor, IL-2 receptor, T10, and gp24, were compared and investigated together with the T13 structure, recently found in this laboratory. T13, not demonstrable on resting T cells, could be seen within 24 hr after lectin stimulation. Kinetics of the appearance were similar to IL-2 receptor and transferrin receptor expression. Ia/DR synthesis was investigated separately for each polypeptide and the cytoplasmic invariant gamma-chain expression could be demonstrated for the first time with a gamma-chain-specific monoclonal antibody VIC-Y1. Moreover, gamma-chain synthesis seems to precede alpha- and beta-chain occurrence in human T cells. In addition, data from quantitative studies on antigenic densities are presented. 相似文献
8.
Loren W. Knapp W. Michael O'Guin Roger H. Sawyer Diane Mitchell Clive L. Bunn 《Experimental cell research》1985,156(2)
The intermediate filament composition of differentiated vertebrate cells provides a stable phenotype which appears to be specifically regulated in each cell type. In order to analyse the regulation of intermediate filament expression we have constructed human somatic cell hybrids from the fusion of the HeLa-derived cell line HEB7A and a normal human diploid fibroblast, GM2291. These parental cells differ with respect to the presence or absence of keratin intermediate filaments. Isolation of independently arising clones produced two classes of hybrids. One class expresses keratin in a stable manner and the other class lacks keratin altogether. Indirect immunofluorescence of hybrid cells using antikeratin antiserum demonstrates that there are variations in the intensity and organization of cytoskeletal keratin staining. SDS-PAGE comparisons of cell extracts from these hybrids indicates that there are quantitative differences in the relative amounts of individual keratin polypeptides as well. These clonal variations have allowed us to begin assessing the consequences of genetic interactions between cell types that are normally capable of closely regulating different subsets of intermediate filament genes. 相似文献
9.
Properties of purifed quinonoid dihydropterin reductase 总被引:5,自引:0,他引:5
S Cheema S J Soldin A Knapp K T Hofmann K G Scrimgeour 《Canadian journal of biochemistry》1973,51(9):1229-1239
10.
Christian Berg Hans Dieter Knapp Ulrich Messner Wolfgang Wiehle 《Folia Geobotanica》1989,24(3):297-304
(Bellevalia ciliata was recorded in north-east Bulgaria south of the Dobrudsha, within field and steppe vegetation. Vegetation records and a distribution map are presented. Based on taxonomic studies it is proposed to combineB. ciliata, B. sarmatica (Pall.) Wor. andB. speciosa Wor. under the oldest nameB. ciliata (Cyr.) Nees. 相似文献