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1.
Marian Irwin 《The Journal of general physiology》1923,5(4):427-428
1. A method is given for determining the chloride content in a drop (less than 0.03 cc.) of the cell sap of Nitella. 2. Chlorides accumulate in the sap to the extent of 0.128 M; this accumulation can be followed during the growth of the cell. The chloride content does not increase when the cell is placed for 2 days in solutions (at pH 6.2) containing chlorides up to 0.128 M. 3. The exosmosis of chlorides from injured cells can be followed quantitatively. When one end of the cell is cut off a wave of injury progresses toward the other end; this is accompanied by a progressive exosmosis of chlorides. 相似文献
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The effects of temperature and light on cell division were studied in synchronized suspensions of the high-temperature strain Chlorella 7–11–05. It was found that the time for incipient cell division, the progress in the process after it started, and the number of cells produced are influenced by temperature and light intensity. Within limits, cell division is generally favored by the increase in temperature. The increase in light intensity first favors cell division then, after the optimal light intensity is attained, a further increase in light intensity inhibits cell division. Observations are discussed in connection with the findings of other investigators. The limitations of cell division by temperature and light intensity are considered to be separate from the effects of these factors on growth. 相似文献
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A method for replacing the cell sap of Nitella with an artificialsolution was introduced. The technique, which is a modificationof KAMIYA and KURODA'S (1, 2), is applicable not only for isotonicbut also for hypertonic or hypotonic solutions. Photometricdeterminations of K+, Na+, Ca++ and Cl proved that thereplacement of the cell sap with the present method is satisfactory.The internodal cell of Nitella, whose cell sap was replacedwith an isotonic solution with a simple composition such asa mixture of KCl, NaCl and CaCl2, can be kept living at leastfor several days, sometimes even for more than one month. (Received September 6, 1963; ) 相似文献
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Theodore J. Smayda 《Journal of phycology》1969,5(2):150-157
The influence of 116 combinations of temperature (2, 7, 12, 16 C), salinity (5–35‰ at 5‰ intervals) and light (5 levels) on the mean daily cell division rate ( K ) of the Narragansett Bay clone of Detonula confervacea was examined following appropriate preconditioning. Growth did not occur at 16 C, but was excellent (K = 1.2–1.5) under certain combinations of light and salinity at 2, 7, and 12 C, being somewhat better at the 2 highest temperature levels. At 32%, and 1100–1200 ft-c, K increased approximately 2.5 fold from 0.6 to 1.5 between 2 and 12 C. A light-temperature relationship was found which had the general trend of an increased optimal light intensity with increasing temperature. Within the optimal salinity range of 15–30‰, the optimal light intensity was 200–600 ft-c at 2 C, 600–1200 ft-c at 7 C, and 1200–1800 ft-c at 12 C. The light-temperature relationship was most pronounced at 2 and 12 C. At 2 C, K decreased with increasing light intensity, but was independent of this factor at higher temperatures. The optimal salinity range of 15–30‰ was independent of temperature negligible growth occurred at 5‰. In situ and in vitro responses of Detonula confervacea to salinity were in general agreement but its pronounced cryophilic preference in nature (usually reaching maximum abundance below 1 C) contrasts with its excellent growth at 12 C in culture. The experiments suggest that termination of the bloom of Detonula confervacea in Narragansett Bay and elsewhere is not solely temperature-dependent. Temperature does not satisfactorily account for its apparent exclusion from waters contiguous to Narragansett Bay and from other more northerly portions of the northeastern coast of the U.S, or, together with light, for its equally surprising apparent unimportance in Norwegian coastal waters. 相似文献
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The rate of cyclosis, the value of resting potential and theexcitability were studied on the Nitella internode whose cellsap was replaced with artificial solutions. K+ to Ca++ ratioin the cell sap should be within 2 to 50 in order to maintainthe normal rate of cyclosis and the resting and action potentialsat least for several days. Replacement of the cell sap witha solution containing Li+, Na+ or Rb+ in place of K+ had noappreciable effect on the activity of the internode for severaldays, while gradual but marked decrease in the rate of cyclosisand the resting potential was observed with Cs+. There was noappreciable difference between the effects of Cl andNO3 on cyclosis, resting and action potentials, whileSO4 decreased them to some extent. The rate ofcyclosis was not affected appreciably by changes in osmoticconcentration between 0.17 and 0.30 M. (Received September 6, 1963; ) 相似文献
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INFLUENCE OF IONIC CONDITIONS ON CELL DIFFERENTIATION AND MORPHOGENESIS OF THE CELLULAR SLIME MOLDS 总被引:9,自引:4,他引:5
YASUO MAEDA 《Development, growth & differentiation》1970,12(3):217-227
Effects of various ionic conditions on the development of the cellular slime molds D. discoideum and D. mucoroides were studied. A certain concentration of lithium ions (7 mM) promoted differentiation of the stalk cells and conversely inhibited formation of the spores. The presence of calcium and magnesium ions was needed for Li to manifest its specific effect. A high concentration of Ca (100-120 mM) also facilitated differentiation of the stalk cells. On the other hand, fluoride ions stimulated considerable formation of spores at 15 mM. In the absence of divalent cations, sodium ions inhibited morphogenesis and cell differentiation proportionately with its concentration, and complete inhibition was obtained at 20 mM. The inhibitory effect of Na was nullified by addition of small amounts of Ca. Possible mechanisms by which these ions exert their influences on development of this organism were discussed. 相似文献
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Dissociated cells of lens epithelia of adult rats were monolayerly cultured in vitro. After about 15–20 days' period of active cell growth, such characteristic structures that correspond to "lentoid bodies" described previously in chick cultures were formed. These structures consisted of elongated cells, ultrastructural profile of which was similar with lens fiber. The presence of gamma-crystallin, a marker molecule specific to mature lens fiber, was confirmed in these elongated cells by means of fluorescent antibody technique. The differentiation of lens fiber in vitro was also recognized in clones originating from single lens epithelial cells cultured at very low cell density. 相似文献
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THE INFLUENCE OF DRY STORAGE TEMPERATURE ON THE RESPONSE OF BROMUS STERILIS L. SEEDS TO LIGHT 总被引:1,自引:0,他引:1
JANET R. HILTON 《The New phytologist》1984,98(1):129-134
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James P. Grover 《Journal of phycology》1989,25(2):402-405
Allometric relations between physiological processes and cell volume and surface area are combined with the variable-internal-stores model of growth to predict the ability of hypothetical phytoplankton to compete for phosphorus at equilibrium. The analysis shows that for spherical cells, smaller cells are better competitors than large ones. For cells that are very elongated in shape, however, large cells are often better competitors than small ones. The cells predicted to be the best competitors compare favorably in size and shape with the species observed to dominate in phosphorus-limited chemostats at equilibrium. 相似文献
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Marian Irwin 《The Journal of general physiology》1925,9(2):235-253
When the living cells of Nitella are placed in a solution of brilliant cresyl blue containing NH4Cl, the rate of accumulation of the dye in the sap is found to be lower than when the cells are placed in a solution of dye containing no NH4Cl and this may occur without any increase in the pH value of the cell sap. This decrease is found to be primarily due to the presence of NH3 in the sap and seems not to exist where NH3 is present only in the external solution at the concentration used. 相似文献
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KAMIYA NOBURO; TAZAWA MASASHI; TAZAWA MASASHI; TAKATA TAKAKO 《Plant & cell physiology》1962,3(3):285-292
- A method has been developed to measure the hydraulic conductivityof the wall of the internodal cell of Nitella flexilis.
- Therate of water penetration through the cell wall varies linearlywith the hydrostatic pressure difference between the two sidesof the wall, showing that water permeability of the cell wallremains independent of the pressure difference applied.
- Waterpermeability of the cell wall is inversely proportionalto itsthickness It is 30µµmin3{dot}atm3when the thickness of the wall is 10 µ.
- Water permeabilityof the cell wall is the same for inward andoutward water flow.The polar water permeability of the entiremembrane system (walland protoplasmic part) of the living celldemonstrated by KAMIYAand TAZAWA (1) is, therefore, due tothe living protoplasmicpart.
- The ratio of the inward to outward permeability constantsofthe protoplasmic layer alone is higher than that of the entiremembrane system composed of protoplasmic layer and cell wall.
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E. Newton Harvey 《The Journal of general physiology》1942,25(6):855-863
Nitella flexilis cells are not stimulated to "shock stoppage" of cyclosis by suddenly evacuating the air over the water or on sudden readmission of air, or on suddenly striking a piston in the water-filled chamber in which they are kept with a ball whose energy is 7.6 joules, provided the Nitella cell is not moved by currents against the side of the chamber. Sudden increases in hydrostatic pressure from zero to 1000 lbs. or 0 to 5000 lbs. per square inch or 5000 to 9000 lbs. per square inch usually do not stimulate to "shock stoppage" of cyclosis, but some cells are stimulated. Sudden decreases of pressure are more likely to stimulate, again with variation depending on the cell. In the absence of stimulation, the cyclosis velocity at 23°C. slows as the pressure is increased in steps of 1000 lbs. per square inch. In some cells a regular slowing is observed, in others there is little slowing until 4000 to 6000 lbs. per square inch, when a rapid slowing appears, with only 50 per cent to 30 per cent of the original velocity at 9000 lbs. per square inch. The cyclosis does not completely stop at 10000 lbs. per square inch. The pressure effect is reversible unless the cells have been kept too long at the high pressure. At low temperatures (10°C.) and at temperatures near and above (32°–38°C.) the optimum temperature for maximum cyclosis (35–36°C.) pressures of 3000 to 6000 lbs. per square inch cause only further slowing of cyclosis, with no reversal of the temperature effect, such as has been observed in pressure-temperature studies on the luminescence of luminous bacteria. Sudden increase in temperature may cause shock stoppage of cyclosis as well as sudden decrease in temperature. 相似文献
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《The New phytologist》1905,4(8):189-191
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The marine alga Valonia macrophysa contains in its cell sap K and Na in the proportion of 5.72 to 1. In a form regarded as closely related, Valonia ventricosa, growing in similar environment, the ratio of K to Na is as 0.0278 to 1. The former contains no Mg but in the latter it is present. There are other differences in the composition of the sap. These differences bring about a remarkable contrast in behavior in that Valonia ventricosa floats in sea water while Valonia macrophysa sinks. 相似文献