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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 4621

John J. Gilbert; Some Effects of Diet on the Biology of the Rotifers Asplanchna and Brachionus. In: Nutrition in the Lower Metazoa, edited by D.C.Smith and Y.Tiffon, Pergamon Press Oxford and New York, 1980, p.57-71

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: In certain rotifers the size, biomass, shape, population dynamics, and certain life cycle events, such as the occurrence of sexual or parthenogenetic reproduction and the breaking of dormancy, may be controlled by the type of food eaten. In the A. brightwelli - A. intermedia - A. sieboldi series, there is an increasingly pronounced developmental polymorphism in female size and shape controlled by two dietary factors -- tocopherol (vitamin E) and food type. In the absence of tocopherol, females are relatively small, saccate, and amictic (female-producing). When tocopherol is present, they are 50-200% larger in length, may possess characteristic body-wall outgrowths, and are often mictic (male-producing). In A. intermedia and A. sieboldi, there are two tocopherol-dependent morphotypes -- cruciform and campanulate. The latter is induced when the diet consists of congeneric or crustacean prey. Within each morphotype of these species, food type may exert considerable control over body size and shape, biomass, and life-table parameters. In A. sieboldi, saccate females fed on Brachionus are larger, have a greater dry weight biomass, produce more than twice as many offspring, live longer, and can reproduce more rapidly than those fed on Paramecium. In all morphotypes, but especially the tocopherol-dependent ones, large prey induce larger body sizes and disproportionately larger coronae than small prey. Tocopherol-induced body enlargement involves an increase in cell number in certain cellular structures, and increase in nuclear number, size and DNA endoreduplication in some syncytial structures, and additional cytoplasmic growth. The mechanism by which food type can modify or exaggerate these growth responses is not understood. In B. calyciflorus, food type can influence body size, relative length of postero-lateral spines, and the hatching pattern, as well as the hatchability, of resting eggs.