PubMed · 678584
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N R Borodiuk, B N Tarusov. [Longitudinal light scattering effect].. https://pubmed.ncbi.nlm.nih.gov/678584/
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Using the alcian blue-alcian yellow staining method, the neurosecretory system in the eyestalk of the Crayfish Astacus leptodactylus is studied during the period following the first, second, third and fourth moult after hatching. On the basis of their staining affinities, six different cell types are distinguishable, always spread over the four optic ganglia and varying in number depending upon the moment of sampling. A clearly recognizable sinus gland is present in the period following the third and fourth moult after hatching. During the successive stages, there occurs a shift in staining pattern of the sinus gland, which is also expressed by the variation in number of the various stained cell types.
1. O2 uptake was determined for periods of 23-46 h in salt-depleted crayfish held in deionized water (DW) or Na-free media at 10 degrees C. These media were replaced by artificial lakewater media (ALW) containing 0-2-0-6 mM Na and O2 uptake was again determined for periods of 24-66 h. 2. During net ion uptake in ALW the metabolic rate was either elevated or depressed. Standard metabolism in ALW altered by amounts equivalent to 0-1 - 15-5% (mean 6-4 (15) +/- 4-4% S. D.) of the metabolic rate measured during salt-depletion. On three occasions the metabolic rate was elevated by 22-0 - 66-7%, but some of this increase may have been due to locomotor activity. 3. The calculated values for thermodynamic work involved in ion transport were 0-056 - 0-268 J/10 g. h at 10 degrees C, or 1-5 - 7-2% of the mean standard metabolic rate. Most of the observed changes in metabolic rate lie within the limits of experimental error (ca. +/- 7%). Hence the energetic cost of ion transport is too small for direct measurement in intact crayfish.
Analysis of the motor component in feeding behaviour of the crayfish enabled to differentiate it into separate fragments with respect to the targets which are reached due to realization of each of these fragments. It is suggested that separate fragments are realized by some functional blocks which are activated from their own receptive zones by trigger mechanisms. With changing the coordinates of food stimulus the whole structure of the behaviour also changes due to the inclusion of additional fragments (locomotions, rearrangement of postures, activation of the claw extremities, etc.). Since this rearrangement favours the animal in reaching its final target, it may be considered as adaptive one.