Trypsin activity in the hepatopancreas ofMacrobrachium lamarrei (Crustacea: Decapoda)

Summary Trypsin from the hepatopancreas ofMacrobrachium lamarrei showed optimum activity at pH 7.5 and temperature 45°C. The enzyme activity increased with the increase in incubation period and enzyme concentration. Michaelis constant of the enzyme was 2.38×10^–2 M.Acknowledgments. The authors are thankful to University Grants Commission, India for the award of a Junior Research Fellowship.     

Carotenoids ofBetaeus harfordi (Crustacea: Decapoda)

Zusammenfassung Die Carotinoide der GarneleBetaeus harfordi bestehen zu über 93% aus Astaxanthin und seinen Estern. Die tiefblaue äusserliche Farbe wird durch ein Chromoproteid mit unverestertem Astaxanthin gebildet.

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Contribution from the Scripps Institutiom of Oceanography. This research was supported by Research Grant No. GB-5332x-1 from the National Science Foundation awarded to Dr. D. L. Fox.     

In vitro protein synthesis and alpha amylase activity in F cells from hepatopancreas of Palaemon serratus (Crustacea; Decapoda).

In crustaceans, all the steps in the assimilation of food take place in the hepatopancreas. To facilitate the study of this organ, a method for the dissociation of cell types was developed. The hepatopancreas of the prawn Palaemon serratus was mechanically dissociated and the cells separated by Percoll density-gradient centrifugation. The E and R cells had similar densities of around 1.05 g/ml. The F cells were separated into two distinct fractions with densities of 1.075 and 1.082 g/ml. The B cells sedimented at a density of 1.12 g/ml. The ratio between the two populations of F cells was found to vary during the intermolt cycle while B cells disappeared after the molt. When the density gradient fractions were incubated with 3H-leucine, incorporation was highest in the F cell fractions. Measurements of alpha-amylase activity, indicated that the two populations of F cells may be derived from the same cell type.     

Calcitonin-like peptide in the shrimpPalaemon serratus (Crustacea,Decapoda) during the intermolt cycle

Summary A molecule immunologically related to salmon calcitonin has been detected in the hemolymph of the shrimpPalaemon serratus. Its concentration varies inversely with the calcium level during the molt cycle; a maximum (14 ng/ml) is found in the post-molt stage and a minimum (0.5 ng/ml) during the premolt stage.     

Chymotrypsin gene expression during the intermolt cycle in the shrimpPenaeus vannamei (Crustacea; Decapoda)

InPenaeus vannamei, chymotrypsin is present as two isoenzymes in the hepatopancreas. The enzyme has been localized in F-cells by immunocytochemistry using a specific antibody. By in situ hybridization, with a 510 pb cDNA probe encoding for the first 170 amino acids of the shrimp chymotrypsin, mRNA was localized in the same cells. Gene expression was followed during the intermolt cycle by measuring changes in specific activity in crude extracts, and by the estimation of mRNA levels by Northern blots using the same probe. The increase in specific activity in premolt is preceded in early premolt by an increase in the amount of chymotrypsin mRNA. A second increase is observed in postmolt, suggesting a different mode of regulation of gene expression.     

Penaeidins, a family of antimicrobial peptides from penaeid shrimp (Crustacea, Decapoda)

The production of antimicrobial peptides represents a first-line host defense mechanism of innate immunity that is widespread in nature. Only recently such effectors were isolated in crustacean species, whereas numerous antimicrobial peptides have been characterized from other arthropods, both insects and chelicerates. This review presents findings on a family of antimicrobial peptides, named penaeidins, isolated from the shrimp Penaeus vannamei. Their structure and antimicrobial properties as well as their immune function will be discussed through analyses of penaeidin gene expression and peptide distribution upon microbial challenge. Received 21 January 2000; received after revision 10 March 2000; accepted 10 March 2000     

Ultrastructure of the ‘onion bodies’ of the sensory pore X-organ ofParatya tasmaniensis Reik (Crustacea,Decapoda)

Résumé Nous avons étudié l'ultrastructure des «corps en bulbe d'oignon» dans l'organe-X du pore sensoriel ou l'organe de Bellonci de la crevetteParatya tasmaniensis. L'ultrastructure des «corps en bulbe d'oignon» consistent en éléments tabulaires, que nous supposons Être du réticulum endoplasmique agranulaire, orienté dans deux directions. Dans les éléments tubulaires se trouvent des structures semblables aux lysosomes.     

Level of ecdysteroids in the hemolymph of the freshwater prawn,Macrobrachium rosenbergii (Crustacea: Decapoda) in relation to the phenomenon of cheliped autotomy in males

Summary Ecdysteroid titers were determined in the hemolymph of adult freshwater prawn,Macrobrachium rosenbergii, during various stages of the molt cycle, using radioimmunoassay. A comparison was made between hormone levels in males which undergo normal molt and dominant males of the population which periodically commit cheliped autotomy. The latter is a recently discovered phenomenon whereby a male voluntarily sheds off both its long claws at molt, once the ratio between body length and combined claw length reaches a ceiling level of about 13. Shortly before an autotomizing molt, hormone levels were about three times higher than on the eve of a normal molt.10 November 1986     

Sperm activation inBalanus balanoides (Crustacea: Cirripedia)

Summary Ammonium ions alone will activate both vesicula and inseminated spermatozoa ofBalanus balanoides. Maximum activity, however, occurs when inseminated spermatozoa are treated with the blood and oviducal gland fluid ofB. balanoides.Acknowledgments. I should like to thank Mr K. White for the ammonia determinations and Prof. D. J. Crisp and Dr P. A. Gabbott for useful discussions.     

Hemolymph coagulation in Macropipus puber (L.) Crustacea Decapoda. Respective roles of hemolymph and plasma]

The process of coagulation of the hemolymph in Macropipus puber (L.) Crustacea Decapod depends on one or several plasmatic factors and on a thermo-labile cellular factor which does not seem to be specific. The existence of these factors has been demonstrated.     

Coagulation of the hemolymph in Macropipus puber (L)., Crustacea, Decapoda. Electrophoretic demonstration of a plasma component intervening in hemostasis]

Electrophoretical and immuno-electrophoretical analysis of plasma, serum and some plasmatic extracts of Macropipus puber (L). have evidenced the presence in the plasma of a component absent in the serum. This component which disappears from the plasmatic extracts after their coagulation must therefore plays a role in the clotting processes.     

Eyestalk removal and intensive regeneration: joint effects on the molting cycle of Pachygrapsus marmoratus (Crustacea, Decapoda), variability of the critical regeneration stage]

When eyestalk-removal and pereiopod-removal, followed by intensive regeneration, are realized together on the same animal, their accelerative effect on the moulting rate is lower than the effect of only one of these two processes. The critical stage of pereiopod regeneration varies between the moulting stages C4 to D1 according to the physiological state of the Crab.