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Signification biologique des teneurs protéiques et des activités de l'amylase et des protéases chez Artemia salina L.: aspects d'application à l'étude de la nutrition = Biological significance of protein content and of amylase and protease activities in Artemia salina L.: application aspects to nutritive studies
Samain, J.F.; Boucher, J.; Buestel, D. (1976). Signification biologique des teneurs protéiques et des activités de l'amylase et des protéases chez Artemia salina L.: aspects d'application à l'étude de la nutrition = Biological significance of protein content and of amylase and protease activities in Artemia salina L.: application aspects to nutritive studies, in: Persoone, G. et al. (Ed.) Proceedings of the 10th European Symposium on Marine Biology, Ostend, Belgium, Sept. 17-23, 1975: 1. Research in mariculture at laboratory- and pilot scale. pp. 391-417
In: Persoone, G.; Jaspers, E. (Ed.) (1976). Proceedings of the 10th European Symposium on Marine Biology, Ostend, Belgium, Sept. 17-23, 1975: 1. Research in mariculture at laboratory- and pilot scale. IZWO: Wetteren. ISBN 90-6281-001-2. 620 pp., more

Available in  Authors 
    VLIZ: Proceedings [4827]
Document type: Conference paper

Keyword
    Marine

Authors  Top 
  • Samain, J.F.
  • Boucher, J.
  • Buestel, D.

Abstract
    The relations between the activity of the digestive enzymes amylase and proteases were studied on Artemia salina L. For this purpose, a method for measuring the ingestion was developed compatible with the speed of response of the digestive enzymes. It is demonstrated that the proteic density variations in Artemia of the same size are in relation to the food content of their digestive tract. Therefore the measurement of the size and weight of proteins (proteic density) allows the evaluation of the ingestion. With the aid of this method, a daily ingestion rhythm, with bimodal character, could be demonstrated. The influence on the ingestion, of the concentration of food available (Tetraselmis suecica Butcher) was studied in function of the size of the Artemia . During the ingestion cycle, the animals utilize food of different origins, with an intense nutritive activity for small specimens. In the range of concentrations studied, the quantity of food ingested is proportional to the quantity of food available. The analysis of the digestive enzymes, amylase and proteases of Artemia , as a function of the quantityof phytoplankton available, shows the regulation of the synthesis of these enzymes by the nutritional conditions of the environment. The amylase synthesis is activated in relation to the increase in concentration of phytoplankton available. Under the same conditions, on the contrary, the synthesis of proteases levels is suppressed. Maximum and minimum synthesis levels were defined. The amylase/proteases ratio allows to show the adaptation of Artemia to the feeding regime conditions. The comparison of this ratio to the measure of protein ingestion permits to define an optimum assimilation threshold. During the daily rhythm of ingestion, the quantity of ingested phytoplankton is the second regulating factor of amylase synthesis. From this, the specific amylase activity of an Artemia population can theoretically be estimated from the number of specimens in the nutritive phase or in the resting phase and their respective specific activities. During this rhythm, the amylase is activated in the evening in relation to the grazing of the phytoplankton. Particles of another chemical nature activate the amylase and the proteases during a secundary diurnal nutrition. In the medium maintained without phytoplankton, proteases are mainly activated, in this case the particles would correspond either to bacteria or to debris of ecdysis. In media containing phytoplankton, faecal pellets could adjoin these. The daily bimodal rhythm can also be observed in the medium without food. This allows to assume, that the activating mechanism is independent of the food supply. The amylase/protease ratio in Artemia of three different size classes reveals a higher regime diversification for the smaller Artemia . This diversification would be a way to fulfil the energetic needs of the brine shrimp during their exponential growth phase. The interference of the ingested proteins with the determination of specific activity of the digestive enzymes is discussed. It does not affect the primary regulation level, but it can invert the rhythm aspects. Such an interference has not been observed in copepods for which the nutritional conditions in the natural environment never reach the concentrations of phytoplankton utilized in culturing.

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