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191.
Foraging success of largemouth bass at different light intensities: implications for time and depth of feeding 总被引:2,自引:0,他引:2
Laboratory feeding trials were conducted to determine how light intensity affects foraging success by the visual piscivore, the largemouth bass ( Micropterus salmoides ). Foraging success was greater than 95% at light levels ranging from low intensity daylight (2.43 × 102 lx) to moonlight (3 × 10−3 lx), but declined significantly to 62% at starlight (2 × 10−4 lx) and near 0% in total darkness. Over a range of low to high water clarities (0.5, 2.0, and 4.0 m Secchi depth), estimated depth limits for feeding during the day ranged between 5.5 to 44 m and from 1.6 to 13 m at night during a full moon. At starlight, light intensity rapidly attenuated to a level below the feeding threshold within 0.5 m of the surface at all water clarities. The depth of the water column available for feeding in low clarity water (0.5 m Secchi) was 67 and 75% less than at moderate (2.0 m Secchi) and high (4.0 m Secchi) water clarities. The findings illustrate how differences in the light environment can have important ramifications for predator-prey interactions. 相似文献
192.
K. A. Koehler M. K. Jain D. A. Gabriel H. -Y. C. Chang O. P. Malhotra 《Journal of Protein Chemistry》1995,14(7):537-548
The interaction of bovine prothrombin with Ca2+ and Mg2+ ions was investigated by following H+ release as a function of metal ion concentration at pH 6 and pH 7.4 at high and low ionic strength. Prothrombin Ca2+ and Mg2+ binding is characterized by high- and low-affinity sites. M2+ binding at these sites is associated with intramolecular conformational changes and also with intermolecular self-association. The pH dependence of H+ release by M2+ is bell shaped and consistent with controlling pKa values of 4.8 and 6.5. At pH 6 and low ionic strength, both Ca2+ and Mg2+ titrations following H+ release clearly show independent low- and high-affinity binding sites. Laser light scattering reveals that at pH 7.4 and low ionic strength, and at pH 6.0 and high ionic strength, the prothrombin molecular weight is between 73 and 98 kD. At pH 7.4 and high ionic strength, prothrombin is monomeric in the absence of metal ions, but appears to dimerize in the presence of M2+. At pH 6.0 and low ionic strength prothrombin exists as a dimer in the absence of metal ions and is tetrameric in the presence of Ca2+ and remains dimeric in the presence of Mg2+. These results and those for metal ion-dependent H+ release indicate that H+ release occurs concomitantly with association processes involving prothrombin.Abbreviations GLA
-carboxyglutamic acid; fragment 1. amino terminal residues 1–156 of bovine prothrombin
- MES
2-(N-morpholino) ethanesulfonic acid
- MOPS
3-(N-morpholino) propanesulfonic acid
- PS/PC
phosphatidylserine/phosphatidylcholine vesicles
-
ionic strength 相似文献
193.
The unicellular green alga Chlamydomonas reinhardtii synthesizes glycerol as an osmoregulatory metabolite when exposed to high saline concentrations (200 mM NaCl). Response to osmotic stress can be used for biotechnological production of this compound. When synthesis of a substance is linked to photosynthetic capacity and consequently to effective light, the production on a large scale makes an efficient utilization of light necessary. In the present work a model for evaluation of effective light has been tested. 相似文献
194.
利用自制的控温实验槽在暗室内进行医蛭科两种吸血水蛭对光闪烁和水扰动刺激的模拟个体生态实验,实验结果的统计分析表明,日本医蛭在16℃时与照度有极好的正相关关系,而在22℃时成负相关关系,0.2克体重的个体在两种温度对照度的敏感度均大于0.5-0.6克和1.0-1.3克体重的个体,湖北牛蛭在两种温度时与照度均成正相关关系;0.5克体重的个体在16℃时对照度的敏感度大于1.0-3.3克体重的个体9.5- 相似文献
195.
U. Munro R. Wiltschko 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1995,177(3):357-362
To assess the role of skylight polarization in the orientation system of a day-migrating bird, Yellow-faced Honeyeaters (Lichenostomus chrysops, Meliphagidae) were tested in funnel cages for their directional preferences. In control tests in the natural local geomagnetic field under the clear natural sky, they preferred their normal migratory course. Manipulations of the e-vector by depolarizing the skylight or rotating the axis of polarization failed to affect the orientation as long as the natural geomagnetic field was present. When deprived of magnetic information, the birds continued in their normal migratory direction as long as they had access to information from the natural sky, or when either the sun or polarized light was available. However, when sun was hidden by clouds, depolarizers caused disorientation. — These findings indicate that polarized skylight can be used for orientation when no other known cues are available. However in the hierarchy of cues of this species, the polarization pattern clearly ranks lower than information from the geomagnetic field. 相似文献
196.
Under certain culture conditions, cells of the chlorophyte Haematococcus pluvialis accumulate significant amounts of astaxanthin. This study describes biomass and carotenoid production during a sunlight cycle in a continuous culture of growing cells of H. pluvialis and shows that these two parameters are under the control of irradiance. The hourly carotenoid production increases with light intensity and, in our culture conditions, carotenoid accumulation occurs in a few hours and without any morphological change in the algae. These carotenoids seem to be efficient in protecting algal cells against photoinhibition damage if their content is greater than 1% dry biomass. Below this concentration, that is to say in the early hours of high light intensity, dry biomass decreases due to cell lysis. The results demonstrate that secondary carotenoid accumulation in H. pluvialis may occur in the active growth phase and is stimulated from the first hours of sunlight illumination. 相似文献
197.
陕南地区油橄榄生长发育与生态条件关系的研究 总被引:2,自引:0,他引:2
根据定位观测和实地调查资料研究了油橄榄在陕南地区的生长发育和环境条件的关系,油橄榄树的枝条日高生长量为昼夜生长类型。夜间生长高于昼间的121%-160%;6、7、8、9月的生长量占全年生长量的76%。油橄榄树的年生长量和产量状况与土壤含水量和土壤质地性质有密切关系;油橄榄树为阳性树种,在增加光照的环境条件下生长和结实良好,反之较差。 相似文献
198.
199.
200.
M. W. Service 《Entomologia Experimentalis et Applicata》1984,35(1):27-32
Very simply constructed aquatic sticky light traps employing a chemical solution emitting a bright light attracted large numbers of all larval instars, but few pupae of Aedes cantans in trials in England. During April numbers of larvae per trap ranged from 73±14.2 to 163±19.9, whereas dipping with a ladle yielded only 6.9±5.5 to 11.8±7.7 larvae/dip. The traps were also effective in sampling larvae of Culiseta morsitans and in Sierra Leone larvae of Aedes aegypti. It was concluded that sticky light traps could be valuable in sampling relative numbers of mosquito larvae and merited further evaluation.
Résumé Des pièges adhésifs lumineux faciles à réaliser sont construits pour les captures des larves de moustiques. Ils sont formés de paires de boîtes de Pétri en plastique contenant une solution émettrice de lumière provenant de bâtons lumineux chimiques Cyalume®. Chaque piège est recouvert d'une feuille de plastique de 16×16 cm enduite d'une substance qui reste adhésive sous l'eau. Les larves de moustiques attirées vers la source lumineuse viennent se coller à la feuille adhésive.Ces pièges ont été utilisés avec succès en Angleterre pour l'échantillonnage de tous les stades larvaires d'Aedes cantans, mais pas avec le même efficacité pour les nymphes. Des tests plus restreints ont montré que la technique était également utilisable pour les larves de Culiseta morsitans. Les nombres moyens d'A. cantans capturés pendant une piode de 12 h (73±14,2–163±19,9) étaient supérieux à ceux obtenus en plongeant une louche (6,9±5,5–11,8±7,7). En utilisant les pièges adhésifs lumineux, les captures moyennes de C. morsitans étaient également supérieures (12,6±4,7–35,8±8,9) contre (5,7±6,1–8,9±7,8) avec la méthode de la louche.En Sierra Leone, des stades larvaires immatures d'A. aegypti se développant dans des containers de stockage d'eau ont également pu être capturés à l'aide de ces pièges.Bien qu'une évaluation plus poussée soit encore nécessaire, il ne fait aucun doute que ces pièges adhésifs lumineux aient un intérêt considérable pour l'échantillonnage larvaire dans les sites inaccessibles, tels que les trous d'arbres ou les trous de crabes, où les méthodes d'échantillonage classiques sont souvent d'un emploi difficile.相似文献