Das Projekt "Konservierung von Gameten der Regenbogenforelle (Oncorhynchus mykiss)" wird vom Umweltbundesamt gefördert und von Universität Göttingen, Institut für Tierzucht und Haustiergenetik durchgeführt. Objective: The objective of this investigation is to contribute to the knowledge on handling, shipping and preservation of male and female gametes and embryos in rainbow trout (Oncorhunchus mykiss). General Information: In order to have a steady supply of gametes available, fish will be subjected to either a 6 months compressed light programme or melatonin treatment. In order to study the effect of these treatments in depth and obtain physiological cues as to the times when vitellogenesis occurs and mature gametes are available, serum profiles of the relevant reproductive hormones and vitellogenin will be established. Housing and treatment of fish, collection of gametes and experiments involving handling, storage and preservation as well as fertilization trials will be conducted in Goettingen. Hormone and vitellogenesis determinations will be conducted in Sheffield. Unfertilized eggs and embryos at different stages of development will be stored at various temperatures from 4 C downwards. The suitability of extenders (e.g. sucrose) and cryoprotectants as well as different temperatures and cooling and warming rates will be investigated. Special attention will be given to a new freezing technique, called vitrification, which avoids formation of membrane damaging ice crystals. Recently this technique has been successfully applied in this laboratory for the freezing of mammalian embryos. Concerning cryopreservation of rainbow trout sperm, a series of trials will be conducted in order to improve the sucrose extender and its adaptation to the application under field conditions. It will also be attempted to freeze dry trout sperm after appropriate pretreatment (sucrose, vitrification medium). Achievements: Research has been carried out to increase knowledge on handling and preservation of male and female gametes and embryos in rainbow trout (Oncorhynchus mykiss). Long term trials using melatonin implants have been conducted. Analyses for plasma melatonin, steroids, vitellogenin and spawning times are in progress. As a first step an enzyme linked immunosorbant assay (ELISA) system was set up. Using this system, fully validated homologous ELISAs have been established for estradiol and testosterone. An ELISA for melatonin is near completion. Furthermore, a technique to introduce permanently indwelling catheters in trout has been established. The number of sperm required to fertilize an egg before and after cryopreservation has been determined. The results show that 2E6 frozen thawed spermatozoa per egg gave satisfactory fertilization rates. To be on the safe side, 3E6 is recommended. Since the number of fresh spermatozoa per egg required for optimal fertilization was between 2E5 and 3E5, 15 times more frozen spermatozoa are needed. Preliminary experiments, aimed at the freezing of eggs show that there are solution effects from the cryoprotectants on the survival of eggs and embryos...