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doi: 10.1007/BF00025814pmid: N/A
Abstract An overview is provided of the results of biochemical investigations performed on the rotifer Brachionus plicatilis. Hydrolytic enzymes (mostly glycosidases and proteinases) from Brachionus plicatilis were examined in total homogenates and in fractions obtained by differential and by density gradient centrifugations. By this means (1) soluble, (2) membrane associated and (3) lysosomal enzymes could be distinguished. The first two classes are presumed to be involved in extracellular digestion processes. Integument material from Brachionus was prepared by dissolving the rotifer tissues with strong protein denaturants which leave the material of the intrasyncytial dense lamina, or lorica, intact. The lorica material was then dissolved by treatment with denaturants plus disulphide breaking agents, and characterized by electrophoretic methods, by its sensitivity to proteinases and by its cross-reactivity with keratine-antibodies. Application of these methods to other rotifer species has revealed that at least two types of integument-material with differing chemical properties occur in rotifers. Using similar methods trophi-material of the mastax was prepared for morphological as well as chemical examination. These investigations showed that the trophi contain chitin.
Olsen, Yngvar;Reitan, Kjell Inge;Vadstein, Olav
doi: 10.1007/BF00025815pmid: N/A
Abstract Rotifer cultures of Brachionus plicatilis (SINTEF-strain, length 250 μm) rich in ω3 fatty acids were starved for > 5 days at variable temperature (0–18 °C). The net specific loss rate of rotifer numbers were 0.04 day−1 (range 0–0.08 day−1) at 5–18 °C, but reached values up to 0.25 day−1 at 0–3 °C. The loss rate was independent on culture density (range 40–1000 ind ml−1), but was to some extent dependent on the initial physiological state of the rotifers (i.e., egg ratio). The loss rate of lipids was 0.02–0.05 day−1 below 10 °C, where the potential growth rate of the rotifer is low (0–0.09 day−1). The loss rate of lipids increased rapidly for higher temperatures where the rotifer can maintain positive growth, and reached 0.19 day−1 at 18 °C. The Q10 for the lipid loss rate versus temperature was higher than the Q10 for respiration found in other strains. This may suggest that other processes than respiration were involved in lipid catabolism. The content of ω3 fatty acids became reduced somewhat faster than the lipids (i.e. in particular 22:6 ω3), but the fatty acid per cent distribution remained remarkably unaffected by the temperature during starvation. The results showed that rotifer cultures could be starved for up to 4 days at 5–8 °C without essential quantitative losses of lipids, ω3 fatty acids, and rotifers. The rotifers exhausted their endogenous lipids through reproduction (anabolism) and respiration (including enhanced locomotion) at higher temperatures. At lower temperatures, the mortality rate became very high.
Janssen, C. R.;Rodrigo, M. D. Ferrando;Persoone, G.
doi: 10.1007/BF00025816pmid: N/A
Abstract The use of the freshwater rotifer Brachionus calyciflorus as a test organism for ecotoxicological studies was examined. Changes in the feeding-, swimming behavior- and demographic characteristics of the rotifers exposed to increasing concentrations of copper (Cu) were studied and the relationships between the different test parameters and their ecological relevance evaluated. Relatively simple short-term bioassay methods were developed to measure the swimming activity (2 hours) and the filtration (5 hours) rate. Life-table experiments were performed to asses the long-term effects of Cu on the rotifers. Significant reductions in the filtration rate, the swimming activity and the demographic parameter r were observed at 20, 12 and 5 μg 1−1 of Cu, respectively. The implications and the possible ecotoxicological applications of the results are discussed.
Ferrando, M. D.;Janssen, C. R.;Andreu, E.;Persoone, G.
doi: 10.1007/BF00025817pmid: N/A
Abstract The effects of chronic exposure of the freshwater rotifer Brachionus calyciflorus to the toxicants lindane and 3,4-dichloroaniline (DCA), were evaluated. The parameters used to determine the toxicity on these compounds were the age-specific and fertility, and the demographic parameters: intrinsic rate of natural increase (r), generation time (T), net reproductive rate (R o), reproductive value (V x) and life expectancy (e o). All the demographic parameters studied decreased with increasing toxicant concentrations. The use of life tables techniques with B. calyciflorus as a test method for the determination of chronic toxicity of xenobiotics is discussed.
Fernández-Casalderrey, A.;Ferrando, M. D.;Andreu-Moliner, E.
doi: 10.1007/BF00025818pmid: N/A
Abstract The effect of sublethal levels of methylparathion (0, 1, 3, 5, 7 mg l−1) on the freshwater rotifer, Brachionus calyciflorus, during their entire life cycle was studied. Rotifers were fed on two species of unicellular algae: Nannochloris oculata and Chlorella pyrenoidosa; both algal concentrations were 5 × 105 cell ml−1. The parameters used to determine the toxicity of this compound were survival, fecundity, net reproductive rate (R)o, generation time (T), intrinsic rate of natural increase (r), reproductive value (V x/Vo) and life expectancy at hatching (eo). All the demographic parameters studied were affected by methyl-parathion exposure on rotifers fed on both species of algae, but the toxic effect was larger when animals were fed on Chlorella pyrenoidosa; in this case, animals showed a decreased in fertility and also a delayed first reproduction. Sublethal methylparathion levels produced a reduction in most of the parameters selected, especially after exposure to 7 mg l−1, where the animals died before reproducing.
Nogrady, Thomas;Rowe, Toby L. A.
doi: 10.1007/BF00025819pmid: N/A
Abstract The effect of twelve drugs and chemical compounds on the narcosis of Brachionus plicatilis was studied using standardized laboratory conditions. Drug efficacy was compared by calculating EC50 (effective concentration causing narcosis in 50% of animals), time necessary to reach narcosis in 50% of animals, concentration range of activity, and degree of extension after preservation. The local anesthetic Bupivacaine was found to be most effective by all criteria. Our previous data and preliminary field experiments indicated that drug sensitivity varies widely, even between congeneric taxa. The anesthetic effect of carbonated water was also investigated.
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