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991.
E. Dráberová Zdenek Lukás Dagmar Ivanyi Vladimír Viklický Pavel Dráber 《Histochemistry and cell biology》1998,109(3):231-239
The class III β-tubulin isotype is widely used as a neuronal marker in normal and neoplastic tissues. This isotype was, however,
also immunodetected in certain tumours of non-neuronal origin such as squamous cell carcinoma. Using a newly described monoclonal
antibody we compared the distribution of class III β-tubulin in normal and neoplastic tissues. The TU-20 mouse monoclonal
antibody was prepared against a conserved synthetic peptide from the C-terminus of the human class III β-tubulin isotype,
and its specificity was confirmed by immunoblotting, by competitive enzyme-linked immunosorbent assay and by immunofluorescence
microscopy on cultured cells. In different cell lines of various origins the antibody reacted only with neuroblastoma Neuro-2a
cells and with embryonal carcinoma P19 cells stimulated to neuronal differentiation by retinoic acid. Immunohistochemistry
on formaldehyde-fixed paraffin-embedded normal human tissues revealed the presence of the class III β-tubulin isotype in cell
bodies and processes of neuronal cells in the peripheral and central nervous systems. In other tissues, this β-tubulin isotype
was not immunodetected. Class III β-tubulin was found in all cases of ganglioneuroblastoma, ganglioneuroma, medulloblastoma,
neuroblastoma, sympathoblastoma and in one case of teratoma. In contrast, no reactivity was detected in tumours of non-neuronal
origin, including 32 cases of squamous cell carcinoma. The results indicate a specific TU-20 epitope expression exclusively
in neuronal tissues. The antibody could thus be a useful tool for the probing of class III β-tubulin functions in neurons
as well as for immunohistochemical characterisation of tumours of neuronal origin.
Accepted: 29 July 1997 相似文献
992.
Csaba F. Vad Anett Hanny-Endrédi Pavel Kratina András Abonyi Ekaterina Mironova David S. Murray Larysa Samchyshyna Ioannis Tsakalakis Evangelia Smeti Sofie Spatharis Hanrong Tan Christian Preiler Adam Petrusek Mia M. Bengtsson Robert Ptacnik 《Global Change Biology》2023,29(11):3054-3071
Climate change-related heatwaves are major threats to biodiversity and ecosystem functioning. However, our current understanding of the mechanisms governing community resistance to and recovery from extreme temperature events is still rudimentary. The spatial insurance hypothesis postulates that diverse regional species pools can buffer ecosystem functioning against local disturbances through the immigration of better-adapted taxa. Yet, experimental evidence for such predictions from multi-trophic communities and pulse-type disturbances, like heatwaves, is largely missing. We performed an experimental mesocosm study to test whether species dispersal from natural lakes prior to a simulated heatwave could increase the resistance and recovery of plankton communities. As the buffering effect of dispersal may differ among trophic groups, we independently manipulated the dispersal of organisms from lower (phytoplankton) and higher (zooplankton) trophic levels. The experimental heatwave suppressed total community biomass by having a strong negative effect on zooplankton biomass, probably due to a heat-induced increase in metabolic costs, resulting in weaker top-down control on phytoplankton. While zooplankton dispersal did not alleviate the negative heatwave effects on zooplankton biomass, phytoplankton dispersal enhanced biomass recovery at the level of primary producers, providing partial evidence for spatial insurance. The differential responses to dispersal may be linked to the much larger regional species pool of phytoplankton than of zooplankton. Our results suggest high recovery capacity of community biomass independent of dispersal. However, community composition and trophic structure remained altered due to the heatwave, implying longer-lasting changes in ecosystem functioning. 相似文献
993.
CO2 exchange rates per unit dry weight, measured in the field on attached fruits of the late-maturing Cal Red peach cultivar, at 1200 μmol photons m?2S?1 and in dark, and photosynthetic rates, calculated by the difference between the rates of CO2 evolution in light and dark, declined over the growing season. Calculated photosynthetic rates per fruit increased over the season with increasing fruit dry matter, but declined in maturing fruits apparently coinciding with the loss of chlorophyll. Slight net fruit photosynthetic rates ranging from 0. 087 ± 0. 06 to 0. 003 ± 0. 05 nmol CO2 (g dry weight)?1 S?1 were measured in midseason under optimal temperature (15 and 20°C) and light (1200 μmol photons m?2 S?1) conditions. Calculated fruit photosynthetic rates per unit dry weight increased with increasing temperatures and photon flux densities during fruit development. Dark respiration rates per unit dry weight doubled within a temperature interval of 10°C; the mean seasonal O10 value was 2. 03 between 20 and 30°C. The highest photosynthetic rates were measured at 35°C throughout the growing season. Since dark respiration rates increased at high temperatures to a greater extent than CO2 exchange rates in light, fruit photosynthesis was apparently stimulated by high internal CO2 concentrations via CO2 refixation. At 15°C, fruit photosynthetic rates tended to be saturated at about 600 μmol photons m?2 S?1. Young peach fruits responded to increasing ambient CO2 concentrations with decreasing net CO2 exchange rates in light, but more mature fruits did not respond to increases in ambient CO2. Fruit CO2 exchange rates in the dark remained fairly constant, apparently uninfluenced by ambient CO2 concentrations during the entire growing season. Calculated fruit photosynthetic rates clearly revealed the difference in CO2 response of young and mature peach fruits. Photosynthetic rates of younger peach fruits apparently approached saturation at 370 μl CO21?2. In CO2 free air, fruit photosynthesis was dependent on CO2 refixation since CO2 uptake by the fruits from the external atmosphere was not possible. The difference in photosynthetic rates between fruits in CO2-free air and 370 μl CO2 1?1 indicated that young peach fruits were apparently able to take up CO2 from the external atmosphere. CO2 uptake by peach fruits contributed between 28 and 16% to the fruit photosynthetic rate early in the season, whereas photosynthesis in maturing fruits was supplied entirely by CO2 refixation. 相似文献
994.
Liam N. Nash Lucas W. Zorzetti Pablo A. P. Antiqueira Chris Carbone Gustavo Q. Romero Pavel Kratina 《Global Ecology and Biogeography》2023,32(8):1323-1335
Aim
Emerging aquatic insects link aquatic and terrestrial ecosystems across the Earth. Their diversity, abundance and functional importance means their emergence is an important phenological event. Nevertheless, aquatic insect emergence is understudied at a global scale compared to other phenological events, despite changing phenology being one of the most significant ecological responses to climate change. Here, we quantitatively describe the global patterns, and key proposed drivers, of seasonal aquatic insect emergence, to further understand how these patterns might change in the future.Location
Global.Time Period
1950–2018.Major Taxa Studied
Emerging aquatic insects.Methods
We extracted monthly emergence data from 86 studies across 163 sites to construct 1053 annual emergence curves. We parameterized the curves using two complementary metrics of seasonality, which were modelled against geographical and climatic variables to determine the direct and indirect relationships between them.Results
We found clear global trends in aquatic insect emergence patterns across latitude and underlying climates. Between-month variation and temporal restriction of emergence increased from the equator to the poles, going from small, aseasonal fluctuations in the warm, thermally stable tropics to large, seasonal peaks at cooler, thermally unstable higher latitudes. While emergence trends were associated with gradients of precipitation, temperature was the dominant climatic driver of the latitudinal trend.Main Conclusions
These findings suggest that with climate warming, aquatic insects will emerge over longer periods, diluted in abundances and displaying less seasonal emergence patterns with smaller between-month fluctuations. This may result in disruption of ecosystem functions seasonally dependent on aquatic insects, such as riparian predation, pollination and disease transmission. The cross-ecosystem life cycle of aquatic insects means changes to their seasonal patterns of emergence will have impacts in both aquatic and terrestrial ecosystems. 相似文献995.
The preparation of internal reference material, NSC-21 Compost Vitahum, including its stabilization, homogeneity testing,
and evaluation of an interlaboratory comparison in which 19 laboratories took part using several analytical methods is described.
From the results of the intercomparison, consensus values were derived for the contents of Cd, Cu, Ni, Pb, and Zn, whereas
for As, Co, Cr, Fe, Hg and Mn, information values were derived. Bimodal distribution of the As and Cr results was obtained,
presumably because of incomplete dissolution of the elements from the matrix if insufficiently aggressive decomposition procedures
were employed. Some problems encountered were elucidated by application of neutron activation analysis (NAA) in its nondestructive
and destructive (radiochemical) modes. 相似文献
996.
The difference and/or similarity of both approaches, the one ofSo?ava and the one ofBraun-Blanquet, and the reciprocal transferability of the units of cartography is tested using the mapped vegetation of the Siberian steppe as an example. 相似文献
997.
998.
999.
In contrast to conclusions of previous studies /I-3/ claiming the absence of histone HI from the SV40 and polyoma viral minichromosomes we have found that a preparation of purified SV40 minichromosomes does contain histone HI. The content of HI in relation to other four histones in the SV40 minichromosomes is close to that in the cellular chromatin. Histone HI in the isolated SV40 minichromosomes is bound apparently to internucleosomal DNA stretches as was shown already for HI in the cellular chromatin /4/. In addition it was found that more than 90% of the purified SV40 minichromosomes migrated as a single discrete deoxyribonucleoprotein band upon agarose gel electrophoresis. 相似文献
1000.
Selection and some properties of recombinant clones of lambda bacteriophage containing genes of Drosophila melanogaster. 总被引:3,自引:3,他引:0
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The lambdagt clones containing fragments of the Drosophila melanogaster genome were prepared and characterized by hybridization of their DNA with (I) lambdagt-cRNA; (2) lambdaC-cRNA; (3) Dm-cRNA; (4) the mRNA of D.melanogaster culture cells and (5) the stable cytoplasmic poly (A) RNA from the same source. The technique for a simple selection of hybrid clones is described. The hybridization with mRNA allows one to select the clones containing structural genes of D.melanogaster. It was found that in all cases when the clone contains the structural gene it also contains the reiterated base sequences of the D.melanogaster genome. Several clones containing D. melanogaster DNA fragments with a size of (2-4)x1O6 daltons hybridizing with a relatively large portion of mRNA were selected for further analysis. 相似文献