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1.
2.
THE TIMING OF DIVISION IN CHLAMYDOMONAS 总被引:3,自引:2,他引:1
3.
ANN H. SZYSZKO BESSEMARIE L. PRAZAK CHARLES F. EHRET WILLIAM J. EISLER JOHN J. WILLE 《The Journal of eukaryotic microbiology》1968,15(4):781-785
SYNOPSIS. A multi-unit automatic sampling device for investigation of microbial growth under a wide variety of conditions is described. The kinetics of asynchronous population growth for batch cultures of Tetrahymena pyriformis (W) at several temperatures show that there are 2 distinct growth phases: an exponential ultradian growth phase that is strongly temperature dependent and a non-stationary growth phase, the infradian phase, that shows little or no temperature dependence over the range from 15–27 C. 相似文献
4.
JOSEPH J. NAPOLITANO MARY E. WALL CAROL S. GANZ 《The Journal of eukaryotic microbiology》1970,17(2):158-161
SYNOPSIS. An amoeboflagellate isolated from common soil is described. The amoeboid stage is typically limax and contains a well differentiated uroid region. The flagellate has 2 flagella, which emerge anteriorly and are equal in length. It has a ventral cytostome near the anterior border. The cyst is helmet-shaped and without opercula. Polar masses are present during nuclear division. 相似文献
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6.
MARY OSBORN JÖRG CASELITZ KLAUS WEBER 《Differentiation; research in biological diversity》1981,20(1-3):196-202
The display of the two distinct intermediate filament proteins, desmin and vimentin, in rat vascular smooth muscle tissue was studied by immunofluorescence microscopy on frozen sections of aorta and other blood vessels. Vascular smooth muscle cells present in these vessels always appeared rich in vimentin. However, staining of sections covering six distinct but contiguous parts of the aorta showed that the number of desmin containing cells was low distal to the truncus brachiocephalicus, but increases until in distal parts of the aorta and in the arteria iliaca communis almost all cells appear positive for desmin. Thus blood vessels show heterogeneity of intermediate filament expression not only in cross-section but can also display heterogeneity along their length. Muscular arteries such as the renal artery and the arteria femoralis, as well as arterioles and veins including the vena jugularis and the vena cava also contain desmin. Thus it may be that low numbers of desmin-positive cells are typical of elastic arteries, while muscular arteries and other blood vessels are characterized by large numbers of desmin-positive cells. We discuss whether desmin-positive and desmin-negative vascular smooth muscle cells may perform different functions and raise the possibility that desmin expression may coincide with the turn on of a specially regulated contractility program. 相似文献
7.
The significance of alkaline phosphatase activity in Lough Neagh 总被引:4,自引:0,他引:4
SUMMARY. A study of the eutrophic Lough Neagh was undertaken to ascertain the use of alkaline phosphatase activity as an indicator of phosphorus-limited algal growth. Lough Neagh and its surrounding rivers were monitored during 1974 and 1975. Alkaline phosphatase activity increased in the lough when the algal crop increased and depleted orthophosphate to a growth-limiting concentration. Enzyme activity was appreciable, however, at all other times of the year and may on occasions have been associated with zooplankton. The enzyme activity in the inflowing rivers was much greater than in the lough itself. Depending on enzyme stability the enzyme inputs from rivers could contribute significantly to the lough activity. Sewage disposal works effluent appeared to be a major source of enzyme activity in river water. As the alkaline phosphate activity in Lough Neagh resulted from several sources, increased activity could not be used as a reliable indicator of phosphorus limited algal growth. 相似文献
8.
J. K. JARVIE F.L.S. MARY E. BARKWORTH F.L.S. 《Botanical journal of the Linnean Society. Linnean Society of London》1992,108(3):287-301
JARVIE, J. K. & BARKWORTH, M. E., 1992. Anatomical variation in some perennial Triticeae. Cross-sectional anatomy of glumes and leaf blades was examined in 22 taxa of the perennial Triticeae. The taxa included diploids and polyploids based largely on various combinations of the E, J and S genomes. The objective was to determine how much correlation exists between anatomical characteristics and genomic constitution. The data were analysed by principal co-ordinate and cluster analyses. The results showed that monogenomic species based on different genomes were readily distinguishable on glume and leaf blade features. Most heterogenomic taxa exhibited some aspects of each genome present except in the case of JE allotetraploids, which exhibited no E genome characteristics. 相似文献
9.
Evidence of the mechanical advantage of subsidiary cells wasobtained by simultaneous measurements of turgor pressure potentialsin adjacent subsidiary and guard cells using injection circuitswith two separate needles. In Tradescantia virginiana the mechanicaladvantage approaches two. Using the same technique evidencewas obtained that the Spannungsphase is, in the first place,a turgor relations phenomenon due to the mechanical advantageof epidermal or subsidiary cells. In addition, the evidenceindicated that the elastic properties of guard cell walls mayundergo changes during the Spannungsphase when potassium iontransport commences. During these measurements it was confirmedthat the optimum leaf water deficit for maximum stomatal openingoccurs when the epidermal turgor is near zero. Under these conditionsthe width of the stomatal pore is a function of the turgor pressureof the guard cells, since at zero turgor of the subsidiary cellstheir mechanical advantage has disappeared. 相似文献
10.
Genetic and spatial structure within a swift fox population 总被引:1,自引:0,他引:1