C.E.B.A.S.-AQUARACK: second generation hardware and latest scientific results.

A second version of the C.E.B.A.S.-AQUARACK laboratory prototype was developed which includes a new water recycling system and a "Botanical Component" with higher water plants for nitrate elimination. It was modified by a compact commercial filter system which involves a semi-biological coarse filter, a bacteria filter, gas and heat exchangers and a UV sterilization device. A highly sophisticated process control system offers all possibilities to implement robotics and telescience. With the installation of the Botanical component into the system the first step of the realisation of the conception of a "Closed Equilibrated Biological Aquatic System" is performed. In the scientific frame program the reproductive biology of the main experimental animal, Xiphophorus helleri, plays an important role. After the establishment of a morphological reference system of the stages of sexual maturity in both sexes this is correlated with relevant physiological data as concentrations of sexual steroids in gonadal tissue and plasma. On the brain-pituitary level the ontogeny of the gonadotropin releasing hormone (GnRH) and the gonadotropin (GtH) systems were investigated by immunohistochemistry. Surprisingly gonadotropin was not only localized in the pituitary gland but also in brain neurons and fibers which undergo a distinct ontogenetic development and a major part of which are in close structural relation to the GnRH system. A special chapter pays attention to the role of the C.E.B.A.S.-system in C.E.L.S.S. research.