Mitogen- and isoproterenol-induced changes of [Ca2+]i in T cells attached to a glass substrate were examined. Murine (C57BL/6) splenic T cells were attached to coverslips or 35-mm dishes (MatTek) precoated with Cell Tak® (3.5 µg/cm2). The cells were then loaded with fluorescent dye (2 µg/ml of fura2-AM or fluo3-AM) and changes in [Ca2+]i in a population of cells (using a spectrofluorometer) or in single cells (using a confocal microscope) were measured during continuous superfusion. Population measurements of [Ca2+]i demonstrated that concanavalin A (Con A, 2 or 5 µg/ml) caused an increase in [Ca2+]i that rose to a peak and then declined to a steady state. The concentration-response relationship (0.05–5 µg/ml) had an EC50 of 0.3 µg/ml. Isoproterenol decreased the Con A-induced elevation of steady state [Ca2+]i. In single cell studies, the increase in [Ca2+]i in response to Con A typically occurred in about 50% of the cells in a microscope field, and the delay before activation varied among cells. Taken together, these data demonstrate that Cell Tak® can be used to attach T cells to glass coverslips and will be useful for the study of signaling mechanisms in T cells. 相似文献
Intramolecular excimer formation of 1,3-di(1-pyrenyl)propane (Py-3-Py) and fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) were used to evaluate the effect of ethanol on the rate and range of the lateral mobility and the range of the rotational mobility of bulk bilayer structures of the plasma membrane vesicles (ATCC-PMV) isolated from cultured hybridoma cells (ATCC TIB 216). In a concentration-dependent manner, ethanol increased the excimer to monomer fluorescence intensity ratio (I/I) of Py-3-Py in the ATCC-PMV and decreased the anisotropy (r), limiting anisotropy (r) and order parameter (S) of DPH in the ATCC-PMV. This indicates that ethanol increased both the lateral and rotational mobility of the probes in the ATCC-PMV. Selective quenching of DPH by trinitrophenyl groups was utilized to examine the range of transbilayer asymmetric rotational diffusion of the ATCC-PMV. The anisotropy (r), limiting anisotropy (r) and order parameter (S) of DPH in the inner monolayer were 0.024, 0.032, and 0.069, respectively, greater than calculated for the outer monolayer of the ATCC-PMV. Selective quenching of DPH by trinitrophenyl groups was also used to examine the transbilayer asymmetric effects of ethanol on the range of the rotational mobility of the ATCC-PMV. Ethanol had a greater increasing effect on the range of the rotational mobility of the outer monolayer as compared to the inner monolayer of the ATCC-PMV. It has been proven that ethanol exhibits a selective rather than nonselective fluidizing effect within the transbilayer domains of the ATCC-PMV.This paper was supported in part by a research grant from the Korea Science and Engineering Foundation (KOSEF 88-1013-01) and from the Korea Research Foundation (1991–1993). 相似文献
High percentages of micro-calli and micro-derived embryos were produced from isolated asparagus microspores at late uninucleate stage on MS liquid medium supplemented with 1.0 mg l–1 2,4-D and 0.5 mg l–1 BA. Two types of calli, namely compact callus (CC) and loose callus (LC), were found. Plantlets were regenerated via organogenesis, when these calli were transferred onto MS solid medium supplemented with 1.0 mg l–1 BA and 0.2 mg l–1 IBA 6 weeks. Embryos were produced from liquid cultured microspores, or from solid cultured micro-calli. The frequencies of haploid plant production from organogenesis and embryogenesis were compared. Effects of plant growth regulators on callus production, plantlet regeneration, and haploid plant production were tested. The combination of BA 1.0 mg l–1 and IBA 0.2 mg l–1 resulted the highest precentage of haploid plant production (7.7% from CC, 4.3% from LC).Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- IBA
3-indolybutyric acid
- BA
6-binzyladinine
- NAA
naphtalene acetic acid
- MS
Murashige and Skoog 相似文献
The genes that cause a variety of neurologic and neuromuscular disorders have been mapped to the distal region of Xq. In an effort to isolate genes from this area, a regional genomic library of the distal 30% of Xq was constructed from a single metaphase spread by means of laser microdissection and single unique primer-polymerase chain reaction. Using pooled probes of 1000 clones from the genomic library, human brain cDNA libraries were screened for expressed sequences encoded by this region. From the 250,000 cDNA clones screened so far, 10 nonoverlapping sequences that mapped back to the target portion were isolated. The complete nucleotide sequences of these cDNA clones have been determined. Analysis of the sequences indicates that none has significant similarity to previously characterized primate genes. One sequence mapping to Xq27.3-qter contained an open reading frame of 281 amino acids and was expressed in every tissue tested. This gene, as well as others isolated in this manner, may prove to be a candidate gene for heritable disorders mapping to this region. 相似文献
1. 1. The purposes of this study are to find out the arrangement effects on the vapor pressure gradient across the cotton–nylon double layer and to elucidate changes in the vapor pressure gradient when an additional third layer covers the double layer.
2. 2. Model tests for single, double and triple layer system and wear test for triple layer clothing were conducted.
3. 3. It was found that up to the second layer, dryness of innermost microclimate could be maintained when cotton faced the skin (C/N).
4. 4. However, when more permeable and hydrophobic third layer (UWF) covers the double layer, the microclimate of C/N is no longer drier than N/C.
5. 5. When nylon is exposed to the skin, a larger drop in vapor pressure across the first two layers occurred for both model and wear test.
6. 6. The innermost microclimate was not necessarily kept dry when the outermost layer dissipated more moisture due to the inefficient distribution of moisture.
Noctiluca scintillans is one of the most common harmful algal species and widely known due to its bioluminescence. In this study, the spatial distribution, seasonal variations, and long-term trends of N. scintillans blooms in China and the related drivers were analyzed and discussed. From 1933 to 2020, a total of 265 events of N. scintillans blooms were recorded in Chinese coastal waters, with a total duration of 1052 days. The first N. scintillans bloom occurred in Zhejiang in 1933, and only three events were recorded before 1980. From 1981 to 2020, N. scintillans caused harmful algal blooms (HABs) almost every year, both the average duration and the proportion of multiphase HABs showed an increasing trend. 1986–1992, 2002–2004, and 2009–2016 were the three peak periods with a frequency of no less than five events of N. scintillans blooms per year. In terms of spatial distribution, N. scintillans blooms spread from the Southeast China Sea to the Bohai Sea after 2000, Guangdong, Fujian, and Hebei were the three provinces with the highest numbers of recorded events of N. scintillans blooms. Moreover, 86.8% of the events of N. scintillans blooms occurred in spring (March, April, and May) and summer (June, July, and August). Among environmental factors, the dissolved inorganic phosphate, dissolved silicate and chemical oxygen demand were significantly correlated with the cell density of N. scintillans during N. scintillans blooms, and most of N. scintillans blooms were recorded in the temperature range of 18.0–25.0°C. Precipitation, hydrodynamics, water temperature, and food availability might be the main factors affecting the spatial–temporal distribution of N. scintillans blooms along the Chinese coast. 相似文献
Mineralization of dissolved organic matter (DOM) in thermokarst lakes plays a non-negligible role in the permafrost carbon (C) cycle, but remains poorly understood due to its complex interactions with external C and nutrient inputs (i.e., aquatic priming and nutrient effects). Based on large-scale lake sampling and laboratory incubations, in combination with 13C-stable-isotope labeling, optical spectroscopy, and high-throughput sequencing, we examined large-scale patterns and dominant drivers of priming and nutrient effects of DOM biodegradation across 30 thermokarst lakes along a 1100-km transect on the Tibetan Plateau. We observed that labile C and phosphorus (P) rather than nitrogen (N) inputs stimulated DOM biodegradation, with the priming and P effects being 172% and 451% over unamended control, respectively. We also detected significant interactive effects of labile C and nutrient supply on DOM biodegradation, with the combined labile C and nutrient additions inducing stronger microbial mineralization than C or nutrient treatment alone, illustrating that microbial activity in alpine thermokarst lakes is co-limited by both C and nutrients. We further found that the aquatic priming was mainly driven by DOM quality, with the priming intensity increasing with DOM recalcitrance, reflecting the limitation of external C as energy sources for microbial activity. Greater priming intensity was also associated with higher community-level ribosomal RNA gene operon (rrn) copy number and bacterial diversity as well as increased background soluble reactive P concentration. In contrast, the P effect decreased with DOM recalcitrance as well as with background soluble reactive P and ammonium concentrations, revealing the declining importance of P availability in mediating DOM biodegradation with enhanced C limitation but reduced nutrient limitation. Overall, the stimulation of external C and P inputs on DOM biodegradation in thermokarst lakes would amplify C-climate feedback in this alpine permafrost region. 相似文献
Wistar-Kyoto and spontaneously hypertensive rats received i.v. infusions of cocaine hydrochloride (60 mg/kg per day) for 3, 7, and 14 days, or saline for 7 days. Acute cocaine challenge (40 mg/kg, s.c.) was given to treated and control rats 24 hr after the termination of each infusion period. There were no strain differences in brain levels of cocaine during cocaine infusion, nor after cocaine challenges. There were no strain differences in resting levels of [3H]dopamine release. Release of [3H]dopamine decreased in nuclei accumbens of 7- and 14-day cocaine-infused animals. Release of [3H]dopamine was maximal in both brain regions 2 hr after acute cocaine challenge. After 14 days of cocaine infusion, cocaine challenge in both strains reduced [3H]dopamine release in the nucleus accumbens, but not in the striatum; the reduction being greater in Wistar-Kyoto rats. The behavioral tolerance which accompanies similar cocaine infusion regimens may be related to striatal tolerance to cocaine-induced dopamine release. 相似文献