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141.
142.
Jaroslav Brčák 《Biologia Plantarum》1965,7(2):93-97
Chenopodium species react on infection with tobacco mosaic virus by the formation of chlorotic or necrotic lesions and later by the abscission of infected leaves. A transition of local infection into the stem has been observed exceptionally inChenopodium quinoa, C. hybridum, andC. rubrum, but no systemic infection of the leaves followed. Systemic infection was demonstrated only inC. polyspermum andC. murale. The recovery of new sprouts was demonstrated in C.murale in the late chronic phase of infection. 相似文献
143.
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
144.
Stand microclimate and physiological activity of tree leaves in an oak-hornbeam forest 总被引:1,自引:0,他引:1
Michal Marek Elena Masarovičovà Irena Kratochvílová P. Eliáš D. Janouš 《Trees - Structure and Function》1989,3(4):234-240
Summary In an uneven-aged, multi-species oak-hornbeam forest at Báb, SW Slovakia (former IBP Forest Research Site), a series of micrometeorological and ecophysiological measurements started in 1985. The aims of the work are to improve understanding of physiological processes (photosynthesis, respiration, and transpiration) of adult trees and stand microclimate, to collect data for simulation of the canopy (stand) photosynthesis and for ecological synthesis of the functioning of the forest ecosystem. In this paper, photosynthetically active radiation (PAR), air temperature (AT) and relative humidity (RH), wind speed (WS), and CO2 concentration ([CO2]) in and above the forest are characterized for the fully leaved season, using diurnal courses, vertical profiles and isodiagrams (isopleths). Approximately 50% of incident PAR was absorbed by the upper 4–5 m layer of leaves and only approximately 5% or less penetrated to the forest floor. Vertical gradients of AT and RH were generally low, but large differences in diurnal ranges of AT and RH were observed between vertical levels. The upper leaf canopy greatly reduced WS, and at a height of about 14 m above the ground it was close to zero. The highest diurnal [CO2] maximum and variations occurred at 1 m above the ground, and the lowest above the forest. In good light conditions in the forest, the entire leaf canopy (overstorey and understorey canopy) is a large sink of CO2. At night the forest stand is a source of CO2, the largest internal source being the soil and forest floor. 相似文献
145.
Volume-dependent regulation of ion transport and membrane phosphorylation in human and rat erythrocytes 总被引:2,自引:0,他引:2
Sergei N. Orlov Nikolai I. Pokudin Yuri V. Kotelevtsev Pavel V. Gulak 《The Journal of membrane biology》1989,107(2):105-117
Summary Osmotic swelling of human and rat erythrocytes does not induce regulatory volume decrease. Regulatory volume increase was observed in shrunken erythrocytes of rats only. This reaction was blocked by the inhibitors of Na+/H+ exchange. Cytoplasmic acidification in erythrocytes of both species increases the amiloride-inhibited component of22Na influx by five- to eight-fold. Both the osmotic and isosmotic shrinkage of rat erythrocytes results in the 10- to 30-fold increase of amiloride-inhibited22Na influx and a two-fold increase of furosemide-inhibited86Rb influx. We failed to indicate any significant changes of these ion transport systems in shrunken human erythrocytes. The shrinking of quin 2-loaded human and rat erythrocytes results in the two- to threefold increase of the rate of45Ca influx, which is completely blocked by amiloride. The dependence of volume-induced22Na influx in rat erythrocytes and45Ca influx in human erythrocytes on amiloride concentration does not differ. The rate of45Ca influx in resealed ghosts was reduced by one order of magnitude when intravesicular potassium and sodium were replaced by choline. It is assumed that the erythrocyte shrinkage increases the rate of a nonselective Ca
o
2+
(Na
i
+
, K
i
+
) exchange. Erythrocyte shrinking does not induce significant phosphorylation of membrane protein but increases the32P incorporation in diphosphoinositides. The effect of shrinkage on the32P labeling of phosphoinositides is diminished after addition of amiloride. It is assumed that volume-induced phosphoinositide response plays an essential role in the mechanism of the activation of transmembrane ion movements. 相似文献
146.
Francisco J. Campoy Maria Dolores Cánovas Encarnación Muñoz-Delgado Cecilio J. Vidal 《Neurochemical research》1989,14(2):197-204
Incubation of membranes derived from sarcotubular system of rabbit skeletal muscle with increasing concentrations of Triton X-100 produced both stimulation of the AChE activity and solubilization of this enzyme. Mild proteolytic treatment of microsomal membranes produced a several fold activation of the still membrane-bound acetylcholinesterase (AChE) activity. Attempts were made to solubilize AChE from microsomal membranes by proteolytic treatment. About 30–40% of the total enzyme activity could be solubilized by means of trypsin or papain. Short trypsin treatment of the microsomal membranes produced first an activation of the membrane-bound enzyme followed by solubilization. Incubation of muscle microsomes for a short time with papain yielded a significant portion of soluble enzyme. Membrane-bound enzyme activation was measured after a prolonged incubation period. These results are compared with those of solubilization obtained by treatment of membranes with progressive concentrations of Triton X-100. The occurrence of molecular forms in protease-solubilized AChE was investigated by means of centrifugation analysis and slab gel electrophoresis. Centrifugation on sucrose gradients revealed two main components of 4.4S and 10–11S in either trypsin or papain-solubilized AChE. These components behaved as hydrophilic species whereas the Triton solubilized AChE showed an amphipatic character. Application of slab gel electrophoresis showed the occurrence of forms with molecular weights of 350,000; 175,000; 165,000; 85,000 and 76,000. The stimulation of membrane-bound AChE by detergents or proteases would indicate that most of the enzyme molecules or their active sites are sequestered into the lipid bilayer through lipid-protein or protein-protein interactions and these are broken by proteolytic digestion of the muscle microsomes. 相似文献
147.
A systematic reassessment of megafossil records ofFagaceae in Central Europe has been undertaken on the basis of leaf cuticular characters. The oldest representatives date back to the Eocene:Quercus subhercynica spec. nova,Dryophyllum furcinerve (Rossm.)Schmalh.,Trigonobalanopsis rhamnoides (Rossm.) gen. & comb. nov. In the Oligocene other members of extant genera appear:Quercus rhenana (Weyl. & Kilpp.)Knobloch & Kvaek,Fagus attenuata
Goepp.,Lithocarpus saxonicus spec. nova. In the Neogene these ancient taxa (except inFagus lineage), are gradually replaced by deciduous species ofQuercus andCastanea. Trigonobalanus andCastanopsis are recorded by fruits (or wood) only. 相似文献
148.
R González-Cámpora G Mu?oz-Arias C Otal-Salaverri M Jorda-Heras E García-Alvarez A Gomez-Pascual A Garrido-Cintado A Hevia-Vázquez F Sánchez-Gallego H Galera-Davidson 《Acta cytologica》1992,36(6):905-917
We reviewed 98 cases of fine needle aspiration of soft tissue tumors with histologic confirmation performed during an eight-year period and propose a working morphologic classification based on the most prominent cytologic features. Six main tumor groups are recognized: myxoid, round cells, spindle cells, pleomorphic cells, polygonal cells and well differentiated. We believe that this classification allows recognition of the most common soft tissue tumors while helping with the differential diagnosis of other neoplasia, primary or secondary, with similar morphology and a similar presentation. 相似文献
149.
毛喉鞘蕊花的化学成分研究 总被引:17,自引:4,他引:13
本文报导了,从产于滇东北的毛喉鞘蕊花(Coleus forskohlii Brig)的根茎中分离到四个二萜化合物,经光谱分析鉴定,其结构分别为1α,6β,7α-triacetyl-coleonol—B(1),I-acetyl—forskolin(2),coleonol-B(3),和deacetyl-forskolin(4)。化合物(1)和(2)是首次从该植物中分离到。 相似文献
150.