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141.
Defence and development in a gregarious leaf-mining beetle 总被引:1,自引:0,他引:1
HANS DAMMAN 《Ecological Entomology》1994,19(4):335-343
Abstract.
- 1 The gregarious larvae of the chrysomelid beetle Microrhopala vittata mine the leaves of goldenrods (Solidago spp.). These mines serve both as food and as shelter for the larvae.
- 2 Life-table data and experiments indicated that mine initiation and moves to secondary mines represented especially vulnerable stages during larval development. Leaf mines effectively protected M.vittata against predators in the field.
- 3 Field experiments indicated that larvae hatching from larger clutches of eggs stood a greater chance of surviving to pupation, primarily because larvae hatching in groups proved more successful at initiating leaf mines. Once inside the leaf mine, however, larvae feeding in large groups attained lower adult masses, and were more likely to abandon the natal mine and did so earlier in development because large groups more rapidly destroyed a leaf.
142.
本文用放射性配基[3H]8-OH-DPAT的结合实验显示,自发性高血大鼠(SHR)海马、下丘脑及低位脑干的5-HT1A受体结合位点数较正常Wistar大鼠为多,其中以海马最为显著;脑干的5-HT1A受体虽较正常Wistar大鼠多,但不太明显。SHR下丘脑中5-HT1A受体除结合位点较正常Wistar鼠多外,亲和力也有增大。以上结果表明,SHR与正常Wistar大鼠之间各脑区中5-HT1A受体的差别可能与高血压病的发生有关。 相似文献
143.
Vascular smooth muscle cell membranes from prehypertensive rats of the Milan hypertensive strain (MHS) were used to examine adenylyl cyclase activity and its regulation by guanine nucleotide regulatory proteins (G-proteins). Basal adenylyl cyclase activity was similar in MHS and Milan normontensive strain (MNS) membranes. Forsokolin (10?4 M) produced a significantly greater stimulatory response in MHS membranes, but this was not observed with NaF (10?2 M). Isoporterenol (10?4 M) caused a significantly decreased stimulation of adenylyl cyclase activity in MHS membranes, while prostaglandin E1 (10?5 M) produced similar responses in the two strains. Gi function and GTP responses, as observed by biphasic effects of GTP on isoproterenol-stimulated membranes, were similar in both strains. The levels of Gi2α and Gqα/G11α were similar in the two strains, while the levels of Gsα (44 and 42 kDa forms) and the β-subunit were significantly reduced by ~20% in MHS membranes. The α-subunit of Gi3 was dramatically reduced by ~80% in MHS membranes. The affinities of β-adrenergic receptors for the antagonist, cyanophindolol, were similar in the two strains; however, the number of β-adrenoceptors was substantially reduced in MHS membranes. These findings may be of relevance to altered vascular reactivity and transmembrane ion distribution observed in the MHS. 相似文献
144.
145.
J. L. Albi J. Planas J. Sánchez 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(2):118-122
Glucose metabolism in peripheral blood lymphocytes from the brown trout Salmo trutta has been studied. Glucose is taken up by means of a sodium-independent saturable process (K
m=10.8 mmol·l-1), as well as by simple diffusion. Once within the cell, most of glucose is directed to lactate production through either the Embden-Meyerhof pathway or the hexose-monophosphate shunt. Rates of lactate formation are higher than rates of CO2 formation. Glutamine does not exert an effect on either glucose uptake or glucose metabolism. The present study provides information regarding the nature of energy sources for different cell types in salmonids.Abbreviations 3-OMG
3-O-methyl glucose
- EM
Embden-Meyerhoff pathway
- G6D
glucose-6-phosphate dehydrogenase
- HK
hexokinase
- HMS
hexose monophosphate shunt
- ICDH
isocitrate dehydrogenase
-
K
m
apparent Michaelis constant
- LDH
lactate dehydrogenase
- MCB
modified Cortland buffer
- PBL
peripheral blood lymphocytes
- PFK
fructose-6-phosphate kinase
- PK
pyruvate kinase
- RBC
red blood cells
-
V
max
maximal rate of uptake 相似文献
146.
147.
本文论述了植物雄性不育的类型、原因、诱导和应用,总结了国内外在这方面的研究成果。重点对植物雄性不育的类型给以分析,从而丰富了遗传多样性的内容,展示了雄性不育理论和应用研究的光明前景。 相似文献
148.
Lynne A. Isbell 《Evolutionary anthropology》1994,3(2):61-71
It has long been thought that predation has had important ecological and evolutionary effects on primates as prey. Predation has been theorized to have been a major selective force in the evolution of hominids.1 In modern primates, behaviors such as active defense, concealment, vigilance, flight, and alarm calls have been attributed to the selective pressures of predation, as has group living itself. It is clear that primates, like other animals, have evolved ways to minimize their risk of predation. However, the extent to which they have been able to do so, given other constraints of living such as their own need to acquire food, has not yet been resolved. Perhaps most hotly debated is whether predation has been the primary selective force favoring the evolution of group living in primates. Part of the difficulty in resolving the debate lies in a paucity of direct evidence of predation. This is regrettable yet understandable since primatologists, by definition, focus on the study of primates, not predators of primates (unless these are also primates). Systematic direct evidence of the effects of predation can best be obtained by studying predators that are as habituated to observers as are their primate prey. Until this is done, we must continue to rely on opportunistic accounts of predation and predation attempts, and on systematically obtained indirect evidence. Such data reveal several interesting patterns: (1) although smaller primates may have greater predation rates than larger primates, even the largest primates are not invulnerable to predation; (2) the use by primates of unfamiliar areas can result in higher predation rates, which might be one pressure favoring philopatry, or site fidelity; (3) arboreal primates are at greater risk of predation when they are more exposed (at forest edges and tops of canopies) than in more concealed locations; (4) predation by mammalian carnivores may often be episodic; and (5) terrestrial primates may not experience greater predation than arboreal primates. 相似文献
149.
M. Mandolfino G. Cimino A. Scuteri R. Cordì L. Romano 《Cell biology international》1994,18(4):279-288
Zinc movement across eel and human red blood cell membranes was measured by atomic absorption spectrophotometry. It was observed that:
- 1) In human red blood cells zinc uptake is twice as rapid as in fish red blood cells over a temperature range of 10-40°C. The low rate of zinc uptake in eel red blood cell may be simply the side effect of different surface area to volume ratios for the differences in cell size or, it may be due to the low permeability of bicarbonate through the red blood cell membranes.
- 2) Zinc uptake measured in eel and human red blood cells treated and untreated with external trypsin shows different features. The zinc uptake was reduced by about 40% in treated eel red blood cells with respect to the total uptake of untreated red blood cells. Human red blood cells treated and untreated with trypsin do not show any differences in the amount of zinc transported.
- 3) In fish red blood cells, zinc uptake in NANO3 medium is markedly reduced, compared with that measured in NaCl medium. The [Zn2+i slightly increases in the presence of bicarbonate. In human red blood cells in NANO3 medium the zinc uptake is strongly reduced and the presence of bicarbonate marginally increases the zinc influx.
- 4) In eel red blood cells there seem to be two independent pathways for zinc uptake: one DIDS-sensitive and the other DIDS-insensitive. DIDS 10 μM inhibits only 64% of the total zinc transported. Iincreasing the DIDS concentration did not give more inhibition. In human red blood cells only one DIDS-sensitive pathway for zinc transported seems to exist, because, 2,5 μM DIDS inhibits 97% of zinc uptake.
150.
Elena Driomina Igor Polnikov Victor Sharov Ofelia Azizova Yury Vladimirov 《Free radical research》1994,20(5):279-288
A chemiluminescence (CL) flash kinetics on the addition of Fe2+ ions into oxidized low density lipoprotein (LDL) suspension has been studied. LDL oxidation was carried out at 37°C without and in the presence of 5 or 50 μM of Cu.2+ It has been found that under certain experimental conditions (the addition of excess iron ions, more than 1 mM) the amplitude of CL flash depended almost linearly (1) on the concentration of oxidized LDL and (2) on the extent of LDL oxidation measured as diene conjugates (DC) and 2-thiobarbituric acid-reactive substance (TBARS) accumulation. The corresponding correlation coefficients were: for TBARS - 0.94 and for DC - 0.97, in the case of LDL autooxidation; 0.72 and 0.98, in the case of copper-induced LDL oxidation. A sensitivity of the CL method was shown to be significantly enhanced (by more than two orders) in the presence of CL sensitizer - 2, 3,5, 6-lH,4H-tetrahydro-9-(2' -benzoimidazolyl)-quinolizin-(9, 9a, 1 -gh)coumarin. 相似文献