. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LIGHT AND BUDDING IN HYDRA 81 1907) to induce expulsion of the algae. Despite repeated attempts in our labora- tory, we were unable to develop a viable culture of aposymbiotic Burnett hydra using glycerine, chloramphenicol, or culture in darkness. The culture medium (BVS) (modified from Loomis and Lenhoff, 1956) con- sisted of 100 mg NaHCO3 and 50 mg disodiumethelene-diaminetetraacetate (versene) in a liter of filtered spring water. Stock cultures of several hundred hydra were maintained in three-inch Carolina Culture Dishes
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LIGHT AND BUDDING IN HYDRA 81 1907) to induce expulsion of the algae. Despite repeated attempts in our labora- tory, we were unable to develop a viable culture of aposymbiotic Burnett hydra using glycerine, chloramphenicol, or culture in darkness. The culture medium (BVS) (modified from Loomis and Lenhoff, 1956) con- sisted of 100 mg NaHCO3 and 50 mg disodiumethelene-diaminetetraacetate (versene) in a liter of filtered spring water. Stock cultures of several hundred hydra were maintained in three-inch Carolina Culture Dishes containing 50 ml culture medium and kept in foil-lined light tight boxes. Illumination was pro- vided continuously for twelve hours each day (5:00 AM-5 :00 PM) by a single fifteen watt fluorescent light (Sylvania Cool-white) placed 10 inches from the top of the culture dishes providing a uniform light intensity of approximately 120 X I 80 40 - ~o D CO. 20 FIGURE 2. Effect of 12 hours light/12 hours darkness on asexual reproduction of Burnett Green (triangles), Kenilworth Green (closed circles), and Kenilworth Albino hydra (open circles). 250 foot candles at the level of the cultures. Temperature was maintained at 20° C ±1°. Cultures were provided with freshly-hatched specimens of Artemia nauplii for a period of one hour on alternate days, allowing the hydra to feed to repletion. The cultures were then rinsed and fresh culture medium provided. On non-feeding days the culture solution was changed, and once each week the culture dishes were cleaned to minimize bacterial contamination. These methods provided an environ- ment under which hydra reproduced exclusively by asexual budding during the course of experimentation. Prior to the experiments cultures of all three strains were maintained for several months under these conditions. Experimental cultures consisted of five uniform hydra selected from stock cultures; uniform hydra defined by Lenhoff and Bovaird (1961) as animals
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
