Microanatomical studies on the abdominal stretch receptor organs of the crayfish Astacus fluviatilis L. have been carried out in order to establish a basis for the physiological work that has been, and is being carried out on stretch receptors of various species of crayfish. Important differences have been found between these organs and those previously described by Alexandrowicz for the lobste...

To contribute knowledge of the processing and activation of invertebrate proteolytic enzymes, we studied the metalloprotease astacin, a digestive enzyme from the freshwater crayfish Astacus astacus (decapod crustacean). It is the prototype of the protein family of astacins, members of which occur in organisms from bacteria to man and are involved in a variety of physiological reactions. Accordi...

In the literature about the respiratory physiology of water-breathers, the arterial partial pressure of oxygen, P&o2, is reported to range from about 2 to 10-13 kPa (Shelton etal. 1986; McMahon and Wilkens, 1983). In fish, Shelton etal. (1986) reported that animals with low blood O2-affinity exhibit high P a ^ and vice versa. But in laboratory conditions, the excitation state of the animals may...

We have elucidated some of the mechanisms by which ethanol (EtOH) reduces synaptic efficacy at model glutamatergic synapses. The crayfish phasic and tonic neuromuscular junctions are superb models for directly assessing the effects of EtOH on pre-synaptic components of synaptic transmission. The ability to perform quantal analysis of synaptic transmission has allowed us to assess pre-synaptic a...

Marine animals living high in the rocky intertidal zone experience long durations of aerial emersion, sometimes enduring rapid increases in temperature. To date, much of our understanding of the thermal physiology of intertidal organisms comes from studies in which organisms are exposed to increasing temperatures when immersed, with the added effect of aerial emersion rarely considered. In this...

The oxygen-transporting properties of the haemolymph from the crayfish Austropotamobius pallipes were investigated. The haemolymph concentrations of K, Mg^ and Ca ions, together with the concentration of L-lactate were measured in crayfish before, during and after 24 h emersion. The concentrations of K and Mg"" increased during aerial exposure and returned to pre-emersion levels during immersed...

Molecular genetic approaches are playing an increasing role in conservation science by identifying biodiversity that may not be evident by morphology-based taxonomy and systematics. So-called cryptic species are particularly prevalent in freshwater environments, where isolation of dispersal-limited species, such as crayfishes, within dendritic river networks often gives rise to high intra- and ...

In the Plymouth area, estuarine decapod crustaceans like Carcinus maenas and Palaemon serratus have much higher concentrations of zinc in the blood than marine species such as Homarus vulgaris and Maia squinado. These differences between species with different powers of osmotic and ionic regulation have not been explained, but they were the starting-point of the present work. This is a study of...