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

Area of Science:

• Aquatic Systems Biology
• Reproductive Endocrinology
• Neuroscience

Background:

• The C.E.B.A.S.-AQUARACK laboratory prototype was enhanced with a water recycling system and a "Botanical Component" for nitrate elimination using aquatic plants.
• A compact commercial filter system, including biological and gas/heat exchangers, alongside UV sterilization, was integrated.

Purpose of the Study:

• To advance the concept of a "Closed Equilibrated Biological Aquatic System" (C.E.B.A.S.) by incorporating a botanical component.
• To investigate the reproductive biology and sexual maturation of Xiphophorus helleri.
• To examine the ontogeny of gonadotropin-releasing hormone (GnRH) and gonadotropin (GtH) systems in the brain-pituitary axis.

Main Methods:

• Development and modification of the C.E.B.A.S.-AQUARACK prototype with advanced filtration and a botanical component.
• Establishment of a morphological reference system for sexual maturity stages in Xiphophorus helleri.
• Correlation of morphological data with physiological parameters (steroid concentrations) and immunohistochemical analysis of GnRH and GtH systems.

Main Results:

• The enhanced C.E.B.A.S.-AQUARACK system represents a step towards a closed aquatic ecosystem.
• Morphological and physiological data were correlated for Xiphophorus helleri sexual maturity.
• Gonadotropin was unexpectedly found in brain neurons and fibers, distinct from the pituitary, with a developmental trajectory related to the GnRH system.

Conclusions:

• The integration of a botanical component is a key step in realizing a closed aquatic ecosystem.
• The study provides insights into the reproductive endocrinology and neuroendocrine regulation of Xiphophorus helleri.
• The novel localization and development of gonadotropin in the brain suggest complex neuroendocrine interactions in fish.