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31.
32.
Morphological comparisons are made from the study of 64 specimens belonging to the following species:Squalus acanihias, S. blainvillei, S. megalops andS. acutirostris. The results suggest conspecificity betweenS. acutipinnis andS. megalops. The differences betweenS. blainvillei andS. megalops in the E-Atlantic are stressed. The Indo-Pacific species calledS. blainvillei by Chen et al. (1979) is regarded in this paper as probably an undescribed species. Some consideration on the status of several nominal species and the species grouping withinSqualus are also made. 相似文献
33.
J Aramburu M A Balboa A Ramírez A Silva A Acevedo F Sánchez-Madrid M O De Landázuri M López-Botet 《Journal of immunology (Baltimore, Md. : 1950)》1990,144(8):3238-3247
In the present study we describe a novel functional cell surface molecule, designated as Kp43, which is expressed among leukocytes by NK cells, TCR-gamma/delta + T lymphocytes, and some CD8+ CD56+TCR-alpha/beta + T cell clones. The Kp43 Ag is a 70-kDa disulfide-linked dimer, which migrates in SDS-PAGE under reducing conditions as a single 43-kDa band. Two-color immunofluorescence staining of fresh PBL revealed that only a fraction of CD16+, and of TCR-gamma/delta + T lymphocytes expressed the Ag. The analysis of TCR-alpha/beta + T cell clones showed that a small proportion (2 out of 20) weakly expressed Kp43 together with the CD8 and CD56 molecules. By immunoperoxidase staining of different tissues the anti-Kp43, reactivity was detected exclusively in lymphoid organs, where a minority of scattered cells was stained, and in some liver sinusoidal cells. Essentially all NK cells acquired Kp43 when stimulated with a B lymphoblastoid cell line. By contrast, the pattern of distribution of Kp43 remained stable upon in vitro culture of T-gamma/delta lymphocytes, thus delineating two subsets according to its expression. In lymphokine-activated killer populations, obtained by culturing either PBL or NK cells with high concentration of IL-2, most CD16+ and CD56+ cells became Kp43+. The Kp43-specific mAb inhibited the IL-2-dependent proliferative response of cultured NK and TCR-gamma/delta + T cells without affecting their non-MHC-restricted cytotoxicity. The partial inhibitory effect, which was mediated as well by pepsin digested F(ab')2 fragments, was lost upon reduction to Fab. The anti-Kp43 mAb did not interfere with the specific binding of IL-2 to its surface receptors. Altogether the data point out that the Kp43 dimer is involved in the regulation of the IL-2-dependent proliferative response of NK cells and a subset of TCR-gamma/delta + T lymphocytes. 相似文献
34.
B. Desrues B. Collet M. P. Ramé D. Bourel P. Bourguet A. Martin P. Delaval L. Toujas L. Dazord 《Cancer immunology, immunotherapy : CII》1989,30(5):295-299
Monoclonal antibody Po66, produced by immunization against a patient's lung squamous cell carcinoma was found suitable for the scintigraphic detection of human tumours. Surprisingly, the cellular antigen recognized by Po66 was abundant in the cytoplasm of tumour cells but could not be detected on the surface membrane. In the present work the biodistribution of radiolabelled Po66 and of an unrelated immunoglobulin were studied comparatively after intravenous injection into nude mice bearing lung squamous cell carcinoma grafts. Radioactivity distribution among mouse organs and tumour was analysed by gamma counting and autohistoradiography. After injection, radiolabelled Po66 decreased rapidly from the blood in tumour-bearing animals whereas, in controls, it remained at a level comparable to that of the unrelated immunoglobulin. The antibody seemed slowly trapped by the tumour and, 12 days after its injection, distribution ratios between tumour and mouse organs reached values of 20-30 as against 1 in animals injected with the non-specific immunoglobulin. Autohistoradiographic investigations in the tumour confirmed the slow diffusion rate of the antibody, which remained in the vascular spaces up to the 24th hour after injection and diffused afterwards throughout the clusters of tumor cells. Furthermore, radioactivity was detected in cells which, unexpectedly, seemed morphologically unaltered. These cells, the viability of which remains to be determined, were predominant in the central area of the tumours. The results presented constitute new evidence of the ability of an in vivo injected monoclonal antibody to reach a cytoplasmic target inside non-necrotic cells and suggest that the cells permeable to the antibody might be in defective nutritional conditions. 相似文献
35.
The Wolf-Hirschhorn syndrome (WHS) is caused by a partial deletion in the short arm of chromosome 4 band 16.3 (4p16.3). A unique-sequence human DNA probe (39 kb) localized within this region has been used to search for sequence homology in the apes' equivalent chromosome 3 by FISH-technique. The WHS loci are conserved in higher primates at the expected position. Nevertheless, a control probe, which detects alphoid sequences of the pericentromeric region of humans, is diverged in chimpanzee, gorilla, and orangutan. The conservation of WHS loci and divergence of DNA alphoid sequences have further added to the controversy concerning human descent. 相似文献
36.
CWH41 encodes a novel endoplasmic reticulum membrane N-glycoprotein involved in beta 1,6-glucan assembly. 总被引:4,自引:1,他引:3 下载免费PDF全文
B Jiang J Sheraton A F Ram G J Dijkgraaf F M Klis H Bussey 《Journal of bacteriology》1996,178(4):1162-1171
CWH41 encodes a novel type II integral membrane N-glycoprotein located in the endoplasmic reticulum. Disruption of the CWH41 gene leads to a K1 killer toxin-resistant phenotype and a 50% reduction in the cell wall beta 1,6-glucan level. CWH41 also displays strong genetic interactions with KRE1 and KRE6, two genes known to be involved in the beta 1,6-glucan biosynthetic pathway. The cwh41 delta kre6 delta double mutant is nonviable; and the cwh41 delta kre1 delta double mutation results in strong synergistic defects, with a severely slow-growth phenotype, a 75% reduction in beta 1,6-glucan level, and the secretion of a cell wall glucomannoprotein, Cwp1p. These results provide strong genetic evidence indicating that Cwh41p plays a functional role, possibly as a new synthetic component, in the assembly of cell wall beta 1,6-glucan. 相似文献
37.
M. T. Fernández-Espinar S. Vallés F. Piñaga J. A. Pérez-González D. Ramón 《Applied microbiology and biotechnology》1996,45(3):338-341
Using recombinant DNA techniques, an Aspergillus nidulans multicopy transformant for the gene xlnB coding for the minor X24 xylanase has been constructed. When grown on glucose as sole carbon source this transformant secretes 114 U of xylanase (mg
protein)-1. In this culture condition, X24 is the only xylanase secreted and the predominant protein in the culture filtrate. This strategy has been used to purify
the X24 enzyme to homogeneity. The purified xylanase showed a single band on sodium dodecyl sulphate/ polyacrylamide gel electrophoresis
with a molecular mass of 24 kDa and had an isoelectric point of approximately 3.5. The enzyme was a non-debranching endo-1,4-β-xylan
xylanohydrolase highly specific for xylans and showed optimal activity at pH 5.5 and 52°C. The X24 xylanase had a Michaelis constant, K
m, of 12.43 mg oat spelt xylan ml-1 and a V
max of 1639 μmol min-1 (mg protein)-1.
Received: 17 May 1995/Received last revision: 25 September 1995/Accepted: 29 September 1995 相似文献
38.
Neural control of the expression of a Ca2+-activated K+ channel involved in the induction of myotonic-like characteristics 总被引:2,自引:0,他引:2
Beatriz U. Ramírez Maria Isabel Behrens Cecilia Vergara 《Cellular and molecular neurobiology》1996,16(1):39-49
Summary 1. Expression of the apamin-sensitive K+ channel (SK+) in rat skeletal muscle is neurally regulated. The regulatory effect of the nerve over the expression of some muscle ion
channels has been attributed to the electrical activity triggered by the nerve and/or to a trophic effect of some molecules
transported from the soma to the axonal endings.
2. SK+ channels apparently are involved in myotonic dystrophy (MD), therefore understanding the factors that regulate their expression
may ultimately have important clinical relevance.
3. To establish if axoplasmic transport is involved in this process, we used two experimental approaches in adult rats: (a)
Both sciatic nerves were severed, leaving a short or a long nerve stump attached to the anterior tibialis (AT). (b) Colchicine
or vinblastine (VBL), two axonal transport blockers of different potencies, was applied on one leg to the sciatic nerve. To
determine whether electrical activity affects the expression of SK+ channels, denervated AT were directly stimulated. The corresponding contralateral muscles were used as controls.
4. With these experimental conditions we measured (a) apamin binding to muscle membranes, (b) muscle contractile characteristics,
and (c) electromyographic activity.
5. In the short- and long-nerve stump experiments, 5 days after denervation125I-apamin binding to AT membranes was 2.0 times higher in the short-stump side. This difference disappeared at longer times.
The delayed expression of SK+ channels in the muscle left with a longer nerve stump can be attributed to the extra axoplasm contained in the longer stump,
which maintains a normally repressive signal for a longer period of time. Ten to 15 days after application of axonal transport
blockers we found that the muscle half-relaxation time increased in the drug-treated side and apamin partially reverted the
prolonged relaxation. Myotonic-like discharges specifically blockable by apamin were always present in the drug-treated leg.125I-Apamin binding, which is undetectable in a microsomal preparation from hind leg control muscles, was increased in the drug-treated
preparations. Apamin binding to denervated and stimulated AT muscles was lower than in the contralateral unstimulated muscles
[3.3±1.0 vs 6.8±0.8 (n=4) fmol/mg protein].
6. Our results demonstrate that electrical activity and axoplasmic transport are involved in the control of expression of
SK+ in rat skeletal muscle. However, the increased expression of this channel induces myotonic-like characteristics that are
reversed by apamin. This myotonic activity could be a model for MD. 相似文献
39.
Summary Genes as POT1, HSP104 and SSA3, which are late expressed in laboratory culture conditions are expressed only during the first few days in microvinifications in wine yeast cells. This effect is probably due to the different growth conditions and leads to useless levels of enzyme activity for a reporter gene. However the ACT1 promoter, which is constitutively expressed in laboratory conditions, produces sufficient amounts of enzyme activity in late fermentation phases. 相似文献
40.