Abstract
Germline chimaerism (intra or interspecific) is a technique of great potential in aquaculture. It allows specimens to be obtained that produce gametes whose origins lie in the cells of the donor organism. Chimaerism is usually performed at the mid blastula transition (MBT) stage since this is the last in which embryonic cells remain completely totipotent. Zebrafish are photoperiodic in their egg-laying behaviour and show rapid embryonic development. For chimaerism to be successful, it is of interest to establish the maximum time over which embryonic development can be reversibly arrested. This paper reports the effect on survival of subjecting zebrafish embryos at different stages of development to a water temperature of 16 deg C for different lengths of time. The maximum exposure time after which these embryos were able to resume development following low-temperature-induced developmental arrest became shorter as the embryonic stage exposed became earlier. At the MBT stage, the maximum safe exposure time was 2 h; longer exposure times led to problems in development and survival.
Highlights
Zebraf ish (Brachydanio rerio), which are photoperiodic in their egg-laying behaviour and produce eggs every morning at dawn (Westerfield, 1993), as well as other fish species showing rapid embryonic development, are widely used as animal models in
Two experiments were performed involving 20 dechorionated and 20 non-dechorionated embryos at the mid blastula transition (MBT) stage or earlier
Thermal treatment to arrest development before performing chimaerism should be performed in CH since it is in this medium that cells have to be transplanted into MBT embryos
Summary
The aims of the present work were to determine embryonic resistance to low temperatures in order to try to arrest development completely, and to determine for how long, and under what conditions, early zebrafish embryos can withstand developmental arrest without suffering negative consequences upon its resumption. Two preliminary assays were performed in 10-H embryo medium, the first to determine the threshold (descending) temperature at which non-dechorionated embryo development can be arrested yet which allows it to be resumed. The second preliminary assay attempted to establish the maximum length of time that non-dechorionated embryos at different stages of development could withstand remaining at 16oC yet maintain their ability to resume development.
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