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61.
The T cell receptor V alpha 3 gene segment is associated with reactivity to p-azobenzenearsonate 总被引:10,自引:0,他引:10
The murine T cell receptor V alpha 3 gene segment is associated with reactivity to p-azobenzenearsonate, as indicated by several independent lines of evidence. First, three out of four arsonate-reactive T cell clones tested (two I-Ad-and one I-Ak-restricted) utilized V alpha 3. Second, bulk splenic cultures enriched for arsonate/H-2d and arsonate/H-2k responsive T cells showed increased expression of V alpha 3 mRNA. Third, a V alpha 3-containing alpha chain (Ar-5: arsonate/I-Ad) transferred arsonate responsiveness to an appropriate recipient T cell (O3: ovalbumin/I-Ad). Fourth, an independently derived V alpha 3-expressing T cell clone (2C: alloreactive to Ld) showed a response to arsonate/Ld. Thus, a V alpha 3 gene segment, in conjunction with at least two different J alpha segments (J alpha 20'(Ar-5) and J alpha pHDS58(2C)) and at least three different beta chains (V beta 2(Ar-5), V beta 6(O3), and V beta 8(2C], confers reactivity to arsonate in association with at least three different MHC proteins (I-Ad, I-Ak, and Ld). We suggest that V alpha 3 encodes a protein sequence with a binding site for the arsonate hapten. 相似文献
62.
D. J. Senior P. P. Mayers D. Miller R. Sutcliffe L. Tan J. N. Saddler 《Biotechnology letters》1988,10(12):907-912
Summary The specificity of action of a cellulase-free xylanase preparation on pulp fibers was revealed by the composition of the solubilized products after enzyme treatment. The neutral carbohydrates released by the treatment of two hardwood kraft pulps were composed exclusively of xylooligomers. A similar treatment of Solka Floc showed no detrimental effect on the degree of polymerization of the cellulose fibers, as determined by size exclusion chromatographic analysis. 相似文献
63.
Nodal cuttings of white yam were induced to produce microtubers on a MS-revised medium supplemented with various concentrations of sucrose, 20 mgl–1 L-cysteine, 0.5 mgl–1 kinetin and 0.7% agar. The frequency of tuberization was affected by the daylength, which is optimal at 12 and 16 h of light depending on the sucrose concentration. The microtubers were planted in a seed bed and grown to maturity. The importance of in vitro tuberization of yam as a means of international germplasm distribution or exchange as well as for the propagation of planting material is discussed. 相似文献
64.
65.
1983—1985年,我们进行了胶茶人工群落及胶林、茶园对太阳辐射光谱吸收利用状况的探索研究。着重对可见光谱区的两个吸收带,4000—5000(?)(蓝紫光)、6000—7600A(红橙光)以及红外光谱区的10000—13200(?)(近红外)、14800—18000(?)(远红外)进行了分析讨论,以期从生态和生理的角度阐明群落结构比单一结构的优越性及其对胶、茶产量和品质的影响。 相似文献
66.
67.
Phyllis W. Speisere Maria I. New Grace M. Tannin Donald Pickering Soo Young Yang Perrin C. White 《Human genetics》1992,88(6):647-648
Summary An A-to-G transition in the second intron was the sole mutation detected in four Yupik Eskimo patients with salt-wasting congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency. Allele-specific hybridization should be an efficient means of performing prenatal diagnosis of the disease in this highly inbred population. 相似文献
68.
69.
H C Blair S L Teitelbaum H L Tan P H Schlesinger 《Journal of cellular biochemistry》1992,48(4):401-410
Gallium(III) is a new therapeutic agent for hypercalcemia. Ga3+ reduces osteoclast action, but how it inhibits the cell's physiology is unknown. In vivo, 7-12 microM Ga(III) reduces calcium release from bone, but surprisingly, 10-100 microM Ga3+ added to isolated avian osteoclasts did not reduce their degradation of L-(5-3H)-proline bone. 3H-proline labels bone collagen specifically, and collagenolysis is an excellent indicator of bone dissolution because collagen is the least soluble component of bone. Ga(III) greater than 100 microM inhibited osteoclasts in vitro, but also killed the cells. To resolve this apparent conflict, we measured 67Ga distribution between bone, cells, and media. Gallium binds avidly but slowly to bone fragments. One hundred micrograms of bone clears 60% of 1 microM gallium from 500 microliters of tissue culture medium, with steady state at greater than 24 h. Osteoclasts on bone inhibited gallium binding capacity approximately 40%, indicating a difference in available binding area and suggesting that osteoclasts protect their substrate from Ga binding. Less gallium binds to bone in serum-containing medium than in phosphate-buffered saline; 30% reduction of the affinity constant suggests that the serum containing medium competes with bone binding. Consequently, the effect of [Ga] on bone degradation was studied using accurately controlled amounts of Ga(III) pre-bound to the bone. Under these conditions, gallium sensitivity of osteoclasts is striking. At 2 days, 100 micrograms of bone pre-incubated with 1 ml of 1 microM Ga3+, with 10 pmoles Ga3+/micrograms bone, was degraded at 50% the rate of control bone; over 50 pM Ga3+/micrograms bone, resorption was essentially zero. In contrast, pre-treatment of bone with [Ga3+] as high as 15 microM had no significant effect on bone resorption rate beyond 3 days, indicating that gallium below approximately 150 pg/micrograms bone acts for a limited time and does not permanently damage the cells. We conclude that bone-bound Ga(III) from medium concentrations less than 15 microM inhibits osteoclasts reversibly, while irreversible toxicity occurs at solution [Ga3+] greater than 50 microM. 相似文献
70.
Kah-Siew Tan Takayuki Hoson Yoshio Masuda Seiichiro Kamisaka 《Physiologia plantarum》1991,83(3):397-403
Rice ( Oryza sativa L. cv. Sasanishiki) coleoptiles grown under water achieved greater length than those grown either in air or under water with constant air bubbling. The extensibility of cell walls in coleoptiles grown under water was larger than that in the other treatments. Per unit length of the coleoptile, the content of ferulic and diferulic acids ester-linked to hemicelluloses was higher in air and bubbling type coleoptiles than in water type ones. The extensibility of the coleoptile cell walls correlated with the content of diferulic acids per unit length and per hemicellulose, suggesting that the enhancement of the formation of diferulic acid bridges in hemicelluloses in air or under water with air bubbling makes the cell walls mechanically rigid; thereby inhibiting cell elongation in rice coleoptiles. In addition, the ratio of diferulic acid to ferulic acid was almost constant irrespective of coleoptile age, zone and growth conditions, suggesting that the feruloylation of hemicelluloses is rate-limiting in the formation of diferulic acid bridges in the cell walls of rice coleoptiles. 相似文献