Principles of Genetics and Breeding

9.1.7.3 Labeling of straws,goblets and canes

• Proper labeling of cryopreserved samples is essential. Usually samples are in storage for days, months, or even years before they are thawed.
• Improperly labeled samples can cause delays in processing, and even worse, could cause genetic contamination of pure stocks of fishes.
• The value of samples is directly proportional to the quality of labeling information and record keeping.
• Unlabeled or poorly labeled samples are essentially worthless.

Labeling of straws

• At the minimum, straws used for research should be labeled to indicate fish identification number, cryoprotectant, and cryoprotectant concentration.
• A simple method for labeling is to use straw colour for identification of cryoprotectant and a system of marks on the straws to identify fish number and cryoprotectant concentration.
• Marking could consist of a series of dashes and dots, in which dashes represent the number five and dots represent the number one. Dashes and dots would be summed to yield the final values. For example, fish number can be identified at the top of the straw (near the factory plugging). Cryoprotectant concentration can be marked lower with sufficient space between it and the fish number to allow easy recognition. If, possible, more sophisticated labeling, such as pre-printed straws, should be considered even for research applications.

The basic information that should be recorded is given below.

Fish : species, sex, origin, number.

Preservation details : Date,pre-frozen quality, diluent, dilution rate(s), cooling/warming protocols.

Labeling of goblets

• Straws can be stored in LN₂ in plastic containers called goblets.
• Goblets are manufactured in numerous colours and should be labeled to identify species, date, technician, type of study and additional pertinent information.
• To avoid problems in removing frozen straws do not pack them too tightly in the goblets.

Labeling of canes

• Goblets are usually attached to aluminium canes for storage in LN₂.
• Canes should be labeled on the top for easy identification.
• Labeling will decrease excessive searching of cryocan contents for necessary straws. This helps to protect the straws from warming during handling.