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1.
Calli derived from seedlings of the parasitic plant Orobancheaegyptiaca were grown on enriched nutrient agar. Growth wasenhanced by the addition of 0.1 mg 11 NAA and 5 % coconutmilk. The calli developed two kinds of elongated protrusions:thin ones which resemble the young root radicle and thick oneswhich resemble the adventitious roots of Orobanche plants. Bothformed pad-like structures when touching the substrate. In liquidculture, some of the calli were observed to surround isolatedcultured tomato roots. Orobanche aegyptiaca Pers., in vitro culture, germination, coconut milk, root parasite 相似文献
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Ribulose-l,5-diphosphate (RuDP) carboxylase protein and activitywere determined in relation to net photosynthetic rate duringthe senescence of intact flag leaves of wheat on the plant.Initially the decrease in RuDP carboxylase activity was greaterthan the decline in net photosynthesis. The major decrease inRuDP carboxylase activity over this period resulted from a decreasein enzyme specific activity from 11 to 2 µmol CO2 fixedh1 mg1 protein. Loss of RuDP carboxylase proteindid not occur until late in senescence by which time chlorophyllconcentration had decreased by more than 50%. Treatment of flagleaves at weekly intervals with either 1000 parts 1062-chloro-ethyltrimethylammonium chloride or 100 parts 106gibberellic acid with 1 part 106 kinetin did not significantlyaffect net photosynthetic rate, RuDP carboxylase protein oractivity during senescence. 相似文献
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The effect of exposure period and concentration of algae on the frequency of infection of aposymbiotic ciliates by algae obtained from the same clone of Paramecium bursaria syngen 2, was studied. The frequency of infection was roughly proportional to the algal concentration and to the exposure time of ciliates to algae. The relationship of algal concentration to infection frequency closely fitted the Poisson distribution curve for N = 1, suggesting that the minimum number of algae required to infect a single ciliate is 1. However, the data also strongly suggested that the average number of algae required to initiate infection of an average ciliate was ? 1,000. Three possible resolutions of this situation are: (a) the selection by the ciliate of a rare infective variant from a heterogeneous population: (b) the rare escape of an alga from digestion by the ciliate; and (c) the requirement for a large number of algae-ciliate contacts to induce susceptibility in the ciliate. Splitting the exposure of ciliates to algae into 2 periods of 0.5 h, separated by 5 h in the absence of algae, produced a much higher frequency of infection than a single l-h exposure, supporting the suggestion that the large number of algae is required to induce susceptibility in the ciliate which can then be infected by as few as a single algal cell. 相似文献
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The calcium wave subsequent to fertilization of the egg is analyzed interms of an electrical equivalent circuit. The circuit consists of aswitch, capacitor, an inductor, and a resistor. The switch symbolizes aseries of chemical reactions initiated by the sperm the lead to thedevelopment of the calcium wave. Its closure signifies the onset of thecalcium wave. The capacitor and inductor represent the endoplasmicreticulum. The capacitive component of the endoplasmic reticulum controlsthe release of calcium ions while the inductive component regulates thesequestration of clacium ions. The resistor represents the inductor andcytoplasm and has very low resistance. The analysis of the circuit showsthat the period of the calcium oscillations is proportional to the size ofthe egg. It agrees with the measurements on various types of eggs. 相似文献
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SYNOPSIS. Supraspecific taxa of the ciliate Order Tintinnida Corliss, 1955 are indexed by 304 entries; genetic type species are cited with reference to the original citation. The accompanying bibliography of 133 entries includes those publications cited in the index. Authors for several type citations are corrected, as is authorship of some genera, and a new type designation is made for Parundella to replace the previous erroneous designation. Genera present in the fossil record are so indicated. 相似文献