A simple method for short-term storage and transportation of spermatophores of Pacific white shrimp (Litopenaeus vannamei )

Resumen

The development of a shipping method for spermatophores of the white shrimp Litopenaeus vannamei would open new opportunities for sharing and improving genetic resources of shrimp worldwide. Seventy spermatophores were collected daily for 5 days (a total of 350 spermatophores from 175 shrimp), packed in microcentrifuge tubes containing 100 ?L of an extender solution, and placed in a Styrofoam box supplied with a thermal insulating layer and refrigerant pack to keep the samples cooled at ~14°C. Shipment of samples took ~26 hours. At arrival, spermatophores were randomly sampled either as soon as the box arrived (~27 h, Group A) or five hours later (~32 h, Group B) to assess sperm viability. Spermatozoal morphology was evaluated by microscopy (100 cells per shrimp). Cells without spikes or irregular in shape were recorded as abnormal; otherwise cell morphology was recorded as normal. Spermatozoal viability was assessed by flow cytometry, whereby three populations were identified: (1) cells with intact cytoplasmatic membrane (viable), (2) cells with disrupted membrane (non-viable), and (3) cells in transition, changing from intact to disrupted membrane (transitional). Significant differences were found in spermatozoal morphology between group A and B (p = 0.002), with the highest percentage of normal spermatozoa (92 + 15%) found in Group A. No significant differences were found in viable (p = 0.723) and transitional spermatophore populations (p = 0.595) assessed by flow cytometry. Non-viable populations increased with time in storage (p = 0.039). The highest percentage of non-viable cells (81 + 7%) was obtained in Group B. These results indicate that spermatophores can be cooled and transported to distant locations maintaining normal morphology and viability. These indirect quality indicators suggest that spermatozoa may be used for different purposes, including artificial insemination.