Phylogenetic adaptation of the electrolyte balance and energy metabolism of annelids

 In osmoregulatory species, osmotic concentrations and extracellular ion composition as well as their changes with changing environmental factors are genetically fixed. They give insight into the ecological history of the animals. The aims of our studies are to answer to the following questions: Which adaptations have the electrolyte, water, and energy metabolism in evolution and what was the metabolic state of the ancestial species? Comparative studies on various annelid families exhibit unusualy high concentrations of intermediate metabolites - carbonic acids in the anionic form and parallel a reduced chloride concentration. These results point to a phylogenesis of oligochaetes living in sediments and of parasitic hirudinea in a salt and oxygen reduced environment.

The annelid species of Lake Baikal (Siberia) are mostly endemic. Most species are characterized as relic endemics of the tertiary and therefore as very old. Our results support the hypothesis on the ecological history of oligochaetes and hirudinea. .

 Regulatory mechanisms of the mineral and energy metabolism in Hirudo medicinalis L.

 Medical leeches are living in fresh water, but tolerate brackish water as well (up to 15 ‰ salt concentration). They temporarily burrow themselves into poorly oxygenated muddy ground. Now our experiments have demonstrated that the hypoxic metabolism and ionic regulation are tightly coupled and influence each otherreciprocally:

 1.) Salt stress / higher medium salinity are followed by an increased production and accumulation of metabolites of the hypoxic metabolism - Evidently, this is also necessary for volume regulation.
2.) Environmental hypoxia activates the hypoxic metabolism causing an accumulation of carbonic acids. These carbonic acids function as anions and osmolytes. They are a stress for the organism that is compensated by regulatory mechanisms.

 We are intrested in the regulatory mechanisms, because they can extend our knowledge about metabolic regulation and may give insight into the conditions under which these processes are optimized..

 Mechanisms of ion transport and excretory performance of nephridia in Hirudo medicinalis L.

 Nephridia of annelids are responsible for volume regulation and electrolyte excretion. They are regulatory organs for osmotic and ionic homeostasis in these animals. In the last years our investigations concerning these mechanisms in the medical leech gave insight into the nervous and hormonal control of these regulatory sites. In addition we eludicated the cellular mechanisms of ion transportation in the nephridial epithel.

 Above all, the development of isolated nephridia preparations makes it possible to test the effect of various pharmaceuticals on ion exchange. A comparison of urine formation under various physiological conditions in situ and in vitro in the nephridia of these animals shall give information, whether or not isolated nephridial organs can be objects for the testing of pharmaceuticals.