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The isolation of spirochaetes from the rat caecum 总被引:1,自引:1,他引:0
Spirochaetes indigenous to the conventional rat caecum were cultivated on agar medium using selective isolation techniques. The 27 axenic isolates represented four morphological types of spirochaetes differing in cell size, cell coiling pattern and number of protoplasmic flagella. 相似文献
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CYTOCHROME OXIDASE IN HIGHER PLANTS 总被引:1,自引:1,他引:0
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A COMPARISON OF FEEDING MECHANISMS IN MICROPHAGOUS, HERBIVOROUS, INTERTIDAL, PROSOBRANCHS IN RELATION TO RESOURCE PARTITIONING 总被引:2,自引:0,他引:2
HAWKINS S. J.; WATSON D. C.; HILL A. S.; HARDING S. P.; KYRIAKIDES M. A.; HUTCHINSON S.; NORTON T. A. 《Journal of Molluscan Studies》1989,55(2):151-165
Several microphagous grazers co-exist on British rocky shores.The nature of the microbial film which is their prime food sourceis outlined. The radula morphology, hardness, and feeding mechanismsof rhipidoglossan trochids (Gibbula, Monodonta) taenioglossanLittorina, and docoglossan Patella have been compared. Docoglossanscan penetrate hard substrates deeply, taenioglossans can onlypenetrate softer substrates, and rhipidoglossans appear to primarilybrush the surface. A preliminary study found some differencesin diet. Whether feeding mechanisms allow partitioning of themicrofloral film and whether this allows continuing co-existenceof intertidal grazers is discussed. 相似文献
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DAVID P. FOX BRUCE F. HILL DONALD M. SPOON GEORGE B. CHAPMAN 《The Journal of eukaryotic microbiology》1988,35(1):4-12
ABSTRACT. A sessile, tentacle-bearing protozoon, Heliophrya sp. (Suctoria, Ciliata), reproduces asexually by evaginative budding to form a ciliated swarmer, which begins metamorphosis to the adult form within 30 min of its release from the parent cell. Morphological features of embryogenesis were investigated using transmission and scanning electron microscopy and found to correspond, with certain exceptions, to the few previous reports concerning evaginative budding in suctorians. Following invagination of a portion of the pellicle to form an embryonic cavity within the parent cell, numerous kinetosomes, apparently formed de novo, organize into rows which surround the embryonic cavity and eventually develop cilia that project into the cavity. When the cavity is complete, its walls are extruded through an opening in the parent cell surface. Parent cell cytoplasm streams into the incipient swarmer, thus supplying it with at least the minimum requirement of all cytoplasmic organelles. The ciliated swarmer remains attached to its parent cell for several minutes before it detaches. A complete pellicle is formed in both parent and swarmer prior to detachment. The numerous mitochondria underlying the parent cell pellicle in the vicinity of the attachment area suggest that cross wall formation is an energy-dependent process. 相似文献
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A revised infrageneric classification of Nothofagus (Fagaceae) 总被引:1,自引:0,他引:1
ROBERT S. HILL F.L.S JENNIFER READ 《Botanical journal of the Linnean Society. Linnean Society of London》1991,105(1):37-72
HILL, R. S. & READ, J., 1991. A revised infrageneric classification of Nothofagus (Fagaceae). An examination of cupule morphology, leaf architecture and cuticular morphology of Nothofagus species demonstrates that the existing infrageneric classifications are inaccurate. Four subgenera are proposed, based on these characteristics as well as other morphological information. This analysis indicates that the traditional pollen groupings of Nothofagus closely reflect the infrageneric taxonomy. It is hypothesized that deciduousness is primitive in Nothofagus , and the evergreen habit has arisen more than once, and therefore the deciduous or evergreen habit is invalid as a primary taxonomic character. 相似文献
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Potato plants (Solanum tuberosum L.) were grown in water culturein a controlled environment. Cooling (+8°C) of individualtubers decreased their growth rates and increased the growthrates of non-cooled tubers of the same plant. The carbohydrateconcentration in non-cooled and cooled tubers did not differsignificantly, but 14C-import from labelled photosynthate waslower in cooled than in non-cooled tubers. The markedly lowerconversion rate of ethanol-soluble 14C to starch in cooled,in comparison to non-cooled tubers, was not associated withsignificant differences in the in vitro activities of starchsynthase, ADPG-pyrophosphorylase and starch phosphorylase understandard assay conditions (+30°C). However, the Q10-valuesof the enzymes differed in vitro in the temperature range between30°C and 8°C, leading to a marked decrease in the activityratio of ADPG-pyrophosphorylase/starch phosphorylase in cooledtubers. In tubers differing in growth rates without manipulation, 14d after tuber initiation significant positive correlations werefound between 14C-concentration of tuber tissue and the in vitroactivities of starch synthase and ADPG-pyrophosphorylase anda significant negative correlation between 14C-concentrationand starch phosphorylase. In contrast, in tubers which wereanalysed 5 d after initiation, there were only small differencesbetween tubers in growth rate, 14C import and the activity ratioADPG-pyrophosphorylase/starch phosphorylase. From various directand indirect evidence it is concluded that the growth rate ofindividual tubers, and thus the sink strength, is at least inpart controlled by the activity of starch synthesizing enzymes. Key words: Potato tuber, cooling, starch synthesizing enzymes 相似文献