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TREVOR I. FURNASS 《Freshwater Biology》1979,9(1):33-43
SUMMARY. In laboratory experiments, prey selection of zooplankters by starved perch fry ( Perca fluviatilis ) from Windermere, English Lake District, is temporally variable and there is usually, in the short-term, a persistent succession from one actively selected prey species to another. Provided that the prey is visible, the patterns of prey selection are maintained irrespective of the accessibility of the prey. The fish do not optimize their energy intake per effort. The method of observing predation activity by fish shows qualitative and quantitative prey selection as time progresses in great detail. 相似文献
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Adventitious root initiation in hypocotyls of Pinus radiataD. Don consists of three distinct phases. In the pre-initiativephase, following selection of the cuttings, no histologicalchanges are observed. The initiative phase begins with swellingof a single parenchymatous cell, the meristematic locus. Distinctcytoplasmic changes within the meristematic locus are followedby cytoplasmic migration and asymmetric division in the surroundingcortical or peripheral cells. The third, or post-initiative,phase includes continued division of derivatives of the peripheralcells to form meristemoids which subsequently differentiateinto root primordia. 相似文献
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G. J. LEACH T. WHIFFIN F.L.S. 《Botanical journal of the Linnean Society. Linnean Society of London》1978,76(1):53-69
A hybrid swarm between Acacia brachybotrya and A. calamifolia, involving plants referable to A. grayana, was studied in detail. Plants representing the range of variation found within the hybrid swarm were examined morphologically, chemically and ecologically in an attempt to document hybridisation and to determine their status. Plants referable to A. grayana are confirmed as hybrids, and other intermediate plants are determined as backcrosses to either parent. Phyllode morphology, pollen polyad form and flavonoid composition prove extremely useful in identifying the various elements of the hybrid swarm. Various other aspects of the biology and ecology of the plants in the hybrid swarm are noted. 相似文献
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Involvement of the Embden-Meyerhof Parnas and the pentose phosphatepathways in glucose oxidation in glucose oxidation in tobaccocallus was examined. Marked changes in the activities of glucokinase,aldolase, glucose-6-phosphate dehydrogenase, and phosphogluconatedehydrogenase were observed during culture of tobacco callusunder shoot-forming and non-shoot-forming conditions. Activitiesof these enzymes were higher in shoot-forming tissue than innon-shoot-forming tissue. Furthermore, the activities of thepentose phosphate pathway enzymes showed greater differencesthan those of the Embden-Meyerhof-Parnas pathway. Confirmationof these findings was obtained by investigating the contributionsof 14C from [14C-1]- and [14C6]-glucose to CO2 released.The significance of these findings on glucose oxidation in relationto the shoot-initiation process are discussed. 相似文献