Characterization of a clotting protein, isolated from plasma of the freshwater crayfish Pacifastacus leniusculus

Extracellular acid--base and ionic status, and transbranchial exchange of acidic equivalents and electrolytes, were monitored in freshwater crayfish (Pacifastacus leniusculus) during control normoxia (PO2 = 148 mmHg; 1 mmHg = 133.3 Pa), 72 h of hyperoxia (PO2 = 500 mmHg) and 24 h of recovery. An initial (3 h) respiratory acidosis of 0.2 pH units was completely compensated within 48 h by a 50% increase in metabolic [HCO3−+CO32-] accompanied by a significant reduction in circulating [Cl−]. In addition, the original increase in Pco2 was partially accommodated. The time course of transbranchial acidic equivalent exchange paralleled the change in extracellular metabolic base load with a significant branchial output of H+ during the first 48 h of hyperoxia. This was associated with net branchial effluxes of Cl− and Mg2+. Unidirectional flux analysis revealed parallel reductions in Na+ influx and efflux during initial hyperoxic exposure, reflecting an alteration in exchange diffusion. The net Cl− efflux was due to an initial increase in efflux followed by a reduction in influx. The reverse sequence of events occurred more rapidly when normoxia was reinstated: metabolic base was removed from the haemolymph and control haemolymph acid--base and ion levels were re-established within 24 h. Transbranchial fluxes of acidic equivalents similarly recovered within 24 h although net Na+ output and Cl− uptake persisted. The study attempted to identify relationships between branchial net H+ exchange and components of Na+ and Cl− exchange and quantitatively to correlate changes in the acidic equivalent and electrolyte concentrations in the extracellular fluid compartment with those in the external water.

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Characterization of Oscillatory Olfactory Interneurones in the Protocerebrum of the Crayfish

Journal of Experimental Biology ◽

10.1242/jeb.167.1.15 ◽

1992 ◽

Vol 167 (1) ◽

pp. 15-38

Author(s):

DEFOREST MELLON ◽

DAVID C. SANDEMAN ◽

RENATE E. SANDEMAN

Keyword(s):

Procambarus Clarkii ◽

Lucifer Yellow ◽

Freshwater Crayfish ◽

University Of Virginia ◽

Olfactory Pathway ◽

Electrophysiological Recordings ◽

Burst Period ◽

Electron Microscopical ◽

The Brain

1. We obtained intracellular electrophysiological recordings from local interneurones within the hemi-ellipsoid neuropile of the brain in the freshwater crayfish Cherax destructor and Procambarus clarkii. The recordings were made from perfused, isolated head preparations that provided several indications of a healthy physiological condition. 2. The hemi-ellipsoid interneurones are spontaneously active, generating bursts of action potentials at regular intervals. The inter-burst period differs among neurones, varying from about 1.0 s at the shortest periods to around 30 s for the longest periods. 3. Evidence from both electrophysiological recordings and from injection of Lucifer Yellow and Neurobiotin dyes into hemi-ellipsoid interneurones suggests that some of the cells in the populations are electrically coupled to one another. 4. Hemi-ellipsoid interneurones are driven postsynaptically by axons within the lateral protocerebral tract. Experiments with focal electrical stimulation strongly suggest that the pathways responsible include axons of the olfactory-globular tract. These findings support our previous electron microscopical data showing that olfactory-globular tract axons are presynaptic to the hemi-ellipsoid interneurones. 5. These findings support the conclusion that hemi-ellipsoid interneurones are an integral link in the central olfactory pathway of the crayfish. Note: Present address and address for reprint requests: Department of Biology, Gilmer Hall, University of Virginia, Charlottesville, VA 22901, USA.

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Tyrosinases from crustaceans form hexamers

Biochemical Journal ◽

10.1042/bj20021058 ◽

2003 ◽

Vol 371 (2) ◽

pp. 515-523 ◽

Cited By ~ 65

Author(s):

Elmar JAENICKE ◽

Heinz DECKER

Keyword(s):

Oxygen Carrier ◽

Spiny Lobster ◽

Physicochemical Characterization ◽

Primary Immune Response ◽

Freshwater Crayfish ◽

Astacus Leptodactylus ◽

Purification Protocol ◽

Palinurus Elephas

Tyrosinases, which are widely distributed among animals, plants and fungi, are involved in many biologically essential functions, including pigmentation, sclerotization, primary immune response and host defence. In the present study, we present a structural and physicochemical characterization of two new tyrosinases from the crustaceans Palinurus elephas (European spiny lobster) and Astacus leptodactylus (freshwater crayfish). In vivo, the purified crustacean tyrosinases occur as hexamers composed of one subunit type with a molecular mass of approx. 71kDa. The tyrosinase hexamers appear to be similar to the haemocyanins, based on electron microscopy. Thus a careful purification protocol was developed to discriminate clearly between tyrosinases and the closely related haemocyanins. The physicochemical properties of haemocyanins and tyrosinases are different with respect to electronegativity and hydrophobicity. The hexameric nature of arthropod tyrosinases suggests that these proteins were the ideal predecessors from which to develop the oxygen-carrier protein haemocyanin, with its allosteric and co-operative properties, later on.

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