Sperm Cryopreservation of the African Turquoise Killifish Nothobranchius furzeri

Sperm cryopreservation is an essential method for the genetic preservation and long-term storage of wild-type and transgenic animal stocks. In addition, it allows for the synchronization of gamete availability and the transport and sharing of lines between different laboratories. Here, we describe a protocol developed in our laboratory for the extraction and cryopreservation of killifish (Nothobranchius furzeri) sperm.

In Vitro Fertilization of the African Turquoise Killifish Nothobranchius furzeri

The ability to perform in vitro fertilization, together with sperm cryopreservation, greatly facilitates the long-term laboratory maintenance of wild-type and transgenic model organisms and helps prevent genetic drift. It is also useful in cases where reproduction may be compromised. In this protocol, we present a method for in vitro fertilization of the African Turquoise killifish Nothobranchius furzeri that is compatible with the use of fresh or cryopreserved sperm.

Nonlethal Blood Sampling from the Killifish Nothobranchius furzeri

Blood withdrawal is a common procedure performed on laboratory animals to monitor key processes and indicators of fish health and physiology, such as hematopoiesis, hemostasis, and lipid and glucose metabolism. Moreover, the ability to extract blood with minimal invasiveness and without sacrificing animals enables repeated sampling, allowing both longitudinal studies of individual animals, as well as reducing the number of experimental animals needed in a study. The African turquoise killifish is an emerging animal model that is progressively being adopted worldwide for aging studies because of its naturally short life span. However, because of the small body size of this species, nonlethal blood collection is a challenging procedure. Here we present a detailed protocol enabling repeated blood sampling from the same individual fish. This method, if correctly executed, is minimally invasive and does not cause any lasting damage. The protocol has been tested on animals spanning from 6 to 24 wk of age and the amount of blood that could be extracted varied from 0.5 to 8 µL, greatly depending on specimen age, sex, and size. This volume is sufficient to perform analyses such as blood glucose measurement, blood cell counts, or histological stains on blood smears.