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81.
Regional localization of polymorphic DNA loci on the proximal long arm of the X chromosome using deletions associated with choroideremia 总被引:13,自引:7,他引:6
Summary In two unrelated families, males have been identified who suffer from choroideremia and at the same time have an interstitial deletion on the proximal long arm of the X chromosome. By high-resolution banding we have characterized the deletion chromosomes as del(X)(q21.1-q21.33) and del(X)(q21.2-q21.31) respectively. By Southern blot analysis we have mapped ten different polymorphic DNA loci relative to the position of the deletion and the choroideremia locus TCD. One probe, p31, was shown to cover one of the breakpoints of the smallest deletion. The following order of the loci was suggested by deletion mapping: cen-DXS106-DXS72-TCD-(DXYS1/DXYS23/DXYS5)-DXYS2-(DXYS12/DXS3)-(DXS17/DXS101)-Xqter. 相似文献
82.
83.
The growth rate of a population of Euphausia lucens from thewest coast of South Africa was estimated from laboratory studiesand from monthly size-frequency distributions of samples collectedover a 1-year period. Laboratory studies indicated that growthrates ranged from 0.131 (larvae) to 0.047 mm day1 (juveniles),while size-frequency distributions suggested a growth rate of{small tilde}0.026 mm day1 for the adults. The mean annualbiomass from the inshore, intermediate and offshore regionsranged from 9.75 to 47.29 mg dry wt m3 with the highestbiomass being found in the inshore region. Calyptopis larvaewere present for most months of the year, indicating continuousrecrwtment. The relative contribution of flesh, moults and eggsto the total annual production was estimated separately forall three regions. Production due to growth (Pg) was estimatedto be 92.71185.60 mg dry wt m3 year1, whileexuviai production (Pe) varied between 60.01 and 281.38 mg drywt m year Production of eggs (Pr) was estimated to range from5.07 to 12.39 mg dry wt m year the lowest value being obtainedin the inshore region. Moult production represented {small tilde}6times the mean biomass in each region, while the P/B ratio forflesh production varied from 3.92 to 8.91, the highest ratiobeing obtained in the offshore region. Total P/B ratios rangedfrom 10.14 to 16.01. 相似文献
84.
Preincubation of brain membranes with phospholipase A2 (PLA2) has been shown previously to affect the binding characteristics of various recognition sites associated with the gamma-aminobutyric acid (GABA) receptor complex. In the present study, we have investigated the effects of PLA2 (from Naja naja siamensis venom) on the functional activity of the GABA receptor/chloride ion channel. PLA2 (0.001-0.02 U/mg protein) preincubation decreased pentobarbital-induced 36Cl- efflux and muscimol-induced 36Cl- uptake in rat cerebral cortical synaptoneurosomes. The effect of PLA2 was prevented by EGTA and two nonselective PLA2 inhibitors, mepacrine and bromophenacyl bromide. The removal of free fatty acids by addition of bovine serum albumin both prevented and reversed the effect of PLA2. Products of the catalytic activity of PLA2, such as the unsaturated free fatty acids, arachidonic and oleic acids, mimicked the effect of PLA2. However, the saturated fatty acid, palmitic acid, and lysophosphatidyl choline had no effect on pentobarbital-induced 36Cl- efflux. Because unsaturated free fatty acids are highly susceptible to peroxidation by oxygen radicals, the role of oxygen radicals was investigated. Xanthine plus xanthine oxidase, a superoxide radical generating system, mimicked the effect of PLA2, whereas the superoxide radical scavenger, superoxide dismutase, diminished the effects of PLA2 and arachidonic acid on pentobarbital-induced 36Cl- efflux. Similarly, the effect of PLA2 was also inhibited by methanol (1 mM), a scavenger of the hydroxyl radical, and by catalase. These data indicate that exogenously added PLA2 induces alterations in membrane phospholipids, possibly promoting the generation of oxygen radicals and fatty acid peroxides which can ultimately modulate GABA/barbiturate receptor function in brain. 相似文献
85.
S P Ford N K Schwartz M F Rothschild A J Conley C M Warner 《Journal of reproduction and fertility》1988,84(1):99-104
Embryonic cell number in miniature pigs inbred for specific SLA haplotypes (a, c, and d) was determined on Day 6 by nuclear staining and, on Days 9 and 11, by DNA analyses (first day of oestrus = Day 0). Pigs exhibiting first behavioural oestrus at 08:00 h were hand-mated to an SLA homozygous boar 12 and 24 h later. Numbers of embryos flushed from uteri at 08:00-10:00 h on Days 6, 9 and 11 were greater (P less than 0.05) for SLAd females than for SLAa or SLAc females, which did not differ (8.2 vs 6.8 and 6.2, respectively). Recovery rates (embryos recovered/CL number) were similar, averaging 75.8% for all three SLA haplotypes. Embryos from SLAd dams contained fewer blastomeres (23 cells) on Day 6 than did embryos from SLAa (89 cells) or SLAc (79 cells) females. The reduced cell numbers of SLAd vs SLAa or SLAc embryos continued to Day 9 (28 vs 107 and 67 ng DNA/embryo) and Day 11 (167 vs 674 and 586 ng DNA/embryo). These results suggest an effect of the SLA complex on preimplantation embryonic development. 相似文献
86.
Effect of nitrogen stress and abscisic acid on nitrate absorption and transport in barley and tomato
F. Stuart Chapin III David T. Clarkson John R. Lenton Colin H. S. Walter 《Planta》1988,173(3):340-351
The potential of barley (Hordeum vulgare L.) and tomato (Lycopersicon esculentum Mill.) roots for net NO
3
-
absorption increased two-to five fold within 2 d of being deprived of NO
3
-
supply. Nitrogen-starved barley roots continued to maintain a high potential for NO
3
-
absorption, whereas NO
3
-
absorption by tomato roots declined below control levels after 10 d of N starvation. When placed in a 0.2 mM NO
3
-
solution, roots of both species transported more NO
3
-
and total solutes to the xylem after 2 d of N starvation than did N-sufficient controls. However, replenishment of root NO
3
-
stores took precedence over NO
3
-
transport to the xylem. Consequently, as N stress became more severe, transport of NO
3
-
and total solutes to the xylem declined, relative to controls. Nitrogen stress caused an increase in hydraulic conductance (L
p) and exudate volume (J
v) in barley but decrased these parameters in tomato. Nitrogen stress had no significant effect upon abscisic acid (ABA) levels in roots of barley or flacca (a low-ABA mutant) tomato, but prevented an agerelated decline in ABA in wild-type tomato roots. Applied ABA had the same effect upon barley and upon the wild type and flacca tomatoes: L
p and J
v were increased, but NO
3
-
absorption and NO
3
-
flux to the xylem were either unaffected or sometimes inhibited. We conclude that ABA is not directly involved in the normal changes in NO
3
-
absorption and transport that occur with N stress in barley and tomato, because (1) the root ABA level was either unaffected by N stress (barley and flacca tomato) or changed, after the greatest changes in NO
3
-
absorption and transport and L
p had been observed (wild-type tomato); (2) changes in NO
3
-
absorption/transport characteristics either did not respond to applied ABA, or, if they did, they changed in the direction opposite to that predicted from changes in root ABA with N stress; and (3) the flacca tomato (which produces very little ABA in response to N stress) responded to N stress with very similar changes in NO
3
-
transport to those observed in the wild type.Abbreviation and symbols ABA
abscisic acid
- Jv
exudate volume
- Lp
root hydraulic conductance 相似文献
87.
Asialoglycoprotein receptor phosphorylation and receptor-mediated endocytosis in hepatoma cells. Effect of phorbol esters 总被引:6,自引:0,他引:6
The asialoglycoprotein (ASGP) receptor on Hep G2 cells undergoes constitutive recycling and ligand endocytosis in the presence of phorbol dibutyrate, at a 50% reduced rate relative to control cells (Fallon, R. J., and Schwartz, A. L. (1986) J. Biol. Chem. 261, 15081-15089). The relevance of receptor phosphorylation to these events was investigated by selective immunoprecipitation of surface receptors with polyclonal anti-human ASGP antiserum and pulse-chase labeling with [32P]orthophosphate to identify subcellular locations of initial receptor phosphorylation events as well as the eventual fate of phosphorylated receptor during recycling. The surface immunoprecipitation method recovers greater than 95% of surface ASGP receptors and only 5% or less of intracellular (brief[35S]methionine pulse-labeled) receptors. With this assay we detected low levels of ASGP receptor phosphorylation at the cell surface in control cells (0.1 mol of P/mol of R) which were rapidly (less than 1 min) stimulated 20-fold by 400 nM phorbol dibutyrate addition (1.7 mol of P/mol of R). Staurosporine, a protein kinase C inhibitor, blocks this stimulation by phorbol. Receptor phosphorylation at early time points in the presence of phorbol esters was restricted to the plasma membrane. Subsequent chase in the presence of excess unlabeled phosphate and phorbol esters lowered [32P] ATPi specific activity by 68% at 1 h. Surface immunoprecipitation during this chase period showed the phosphorylated ASGP receptors were rapidly lost from the cell surface (t1/2 = 20 min). In contrast, examination of intracellular receptor during the pulse-chase experiment in phorbol dibutyrate-treated cells showed the presence of phosphorylated pool(s) of ASGP receptors which were detectable for 6 h of chase. Since no labeled receptor can be detected at the cell surface at this time, the described intracellular phosphorylated receptors are in a non-recycling pool. 相似文献
88.
A J Valente R Delgado J D Metter C Cho E A Sprague C J Schwartz D T Graves 《Journal of cellular physiology》1988,136(3):479-485
Proliferation of smooth muscle cells (SMC) in the arterial intima of man and experimental animals is important in the pathogenesis of atherosclerosis. Vascular SMC proliferation in vitro is stimulated by a number of agents, including the potent protein mitogen, platelet-derived growth factor (PDGF). Recent studies on rat arterial SMC indicate that these cells may, under certain circumstances, synthesize PDGF protein mitogens, suggesting that the regulation of SMC proliferation in vivo may have an autocrine or paracrine component. In this study we demonstrate that cultured nonhuman primate (baboon) aortic SMC transcribe both the PDGF-A and PDGF-B genes but do not secrete detectable mitogenic activity characteristic of native PDGF. The absence of this activity was not due to the presence in the cell conditioned medium of factors inhibitory for PDGF-mediated mitogenic activity. Metabolic labeling of the cells and immunoprecipitation with specific antibodies to human PDGF did not detect a dimeric (30 kDa) PDGF protein in either the intracellular or extracellular compartments, but instead identified PDGF-related proteins of molecular weight 12 kDa and 100 kDa. These data suggest the presence in vascular SMC of a mechanism regulating the translation of PDGF mRNA that may play an important role in the control of SMC proliferation in vivo. 相似文献
89.
Activation properties of T cell receptor-gamma delta hybridomas expressing diversity in both gamma- and delta-chains 总被引:8,自引:0,他引:8
90.
Effect of gamma radiation on resting B lymphocytes. II. Functional characterization of the antigen-presentation defect 总被引:4,自引:0,他引:4
J D Ashwell M K Jenkins R H Schwartz 《Journal of immunology (Baltimore, Md. : 1950)》1988,141(8):2536-2544
The effect of radiation on three discrete Ag-presentation functions in resting B cells was examined: 1) Ag uptake and processing, 2) expression of processed Ag in the context of functional class II molecules, and 3) provision of necessary co-stimulatory, or "second," signals. Analysis of radiation's effect on B cell presentation of intact vs fragmented Ag or its effect on presentation by Ag-pulsed B cells indicated that damage to Ag uptake and processing could not account for the bulk of the radiation-induced Ag-presentation defect. Experiments with phosphatidylinositol hydrolysis as an indirect measure of TCR occupancy suggested that irradiation caused a fairly rapid (within 1 to 2 h) decrease in the ability of the B cell APC to display a stimulatory combination of Ag and class II molecule. Ag dose-response analyses demonstrated that when presenting a fragment of the Ag pigeon cytochrome c to a T cell clone, 3000 rad-treated B cell APC were able to stimulate approximately 50% as much phosphatidylinositol turnover as unirradiated B cells. It was also found that, in contrast to their inability to initiate T cell proliferation, and similarly to chemically cross-linked splenocytes, heavily irradiated resting B cells plus Ag induced a state of Ag hyporesponsiveness in T cell clones. This effect on T cells had the same Ag- and MHC-specificity as did receptor occupancy required for proliferation, indicating that heavily irradiated resting B cells bear functional class II molecules. Co-culture of T cells with allogeneic B cells and syngeneic heavily irradiated B cells or chemically cross-linked splenic APC plus Ag resulted in T cell proliferation and interfered with the induction of the hyporesponsive state. This co-stimulatory function was radiosensitive in resting allogeneic B cells. Together, these data support the hypothesis that the major functional consequences of radiation to resting B cell APC are a reduction in the effective display of Ag plus class II molecules and, probably what is more important, a loss in the ability to provide APC-derived co-stimulatory signals. 相似文献