CryoStore diary - Sheyda Shapouri
March 27, 2025 | NMBU, Norway
Late winter afternoons spent at the Veterinary School were cold and tiring, but the stunning snowy landscapes on the way out the door kept spirits high.
The harsh Norwegian winter is finally drawing to a close, the sun’s coming out, and with this shift in the seasons I’m almost coming up to my first full year here at the Norwegian University of Life Sciences. After what felt like an endless loop of administrative work, organizational tasks, required courses, and planning, I’ve started my first experiment: an investigation into the effects of an L-carnitine supplemented diet on gamete quality in zebrafish.
I also got to take a short microscopy course in January, and learned so much about all different types of microscopes, their specific strengths and uses, and the amazing breadth of information you can collect from just one sample. At some points, I was so fascinated by the images we were seeing and creating it didn’t even feel like a class.
Entering my modern artist era with diatoms and different settings on a light microscope.
In early February, around 350 newly hatched zebrafish began their journey with us. Starting out as tiny, nearly transparent little fry with nothing but a little body and giant eyes, they’ve been receiving live food in the form of artemia that have been dosed with L-carnitine, a supplement that improves energy production and metabolization of fatty acids. This supplemented diet, along with an enriched environment (in the form of super exciting plastic plants) is hopefully going to improve gamete quality for both males and females, and by extension improve the rates at which cryopreserved sperm functions after thawing.
Tiny Zebrafish!
What a huge difference in 20 days!
The mad scientist-esque setup where we hatch and treat our artemia.
These days, my workdays begin and end with going down to feed all of our experimental fish their morning and afternoon feedings (lunch is taken care of by the fish facility technicians) as well as making up the next day’s food. We have two groups receiving L-carnitine treated artemia, a low dose and a high dose. The control groups, as well as the groups receiving just environmental enrichment, are also getting in on some delicious artemia, but theirs is untreated. Along with these twice-daily feedings, I’m also checking the general health and welfare of the fish and periodically cleaning out their tanks or otherwise maintaining their space. In between feedings and mass artemia preparation, I’m also getting training in different laboratory procedures, as well as getting dissection practice whenever I can. I’m glad I can capitalize on these moments of relative downtime to get as much hands-on experience as possible in preparation for future experiments.
This study has some interesting implications, how are we setting up our experimental animals for gamete cryopreservation? Is it not in our and their best interest to ensure they receive a complete, nutritionally wholesome diet prior to gamete extraction to improve the overall result and reduce waste from freezing damage? While the cryopreservation of sperm in fish is incredibly commonplace, inevitable losses in the form of reduced motility and numbers make a dent in final post-thaw yield. If sperm quality (both fresh and frozen) can be improved with a supplemented live food diet, both aquaculture industries and conservation efforts of threatened fish species stand to benefit significantly.
Strength in numbers against the giant phone camera that bothers them almost every day.
Come June, these fish will be sampled, and the effects of this enriched diet will be examined from a number of different angles. Firstly, immediately after sampling, fresh sperm will be analyzed using CASA, comparing motility and general health between the control groups and those that received an enriched diet. Length and weight of the groups will be compared, and a post-stress cortisol study will be performed to analyze how an enriched diet can potentially affect the stress response. Additionally, both sperm and eggs will be evaluated for quality post-sampling and used for IVF to examine both fertilization and evaluate the subsequent embryos. The sampling process is sure to be hectic and busy but I’m excited to see what the results tell us!
All in all, as I’m finally fully settling into life here in Norway and at NMBU, I can safely say these last eight months or so have been one of the most exciting adventures I’ve ever taken on, and this is only the start! Everybody at VET has been so welcoming and fun to hang out with every day, and I’ve been loving the experience of getting to take care of my experimental fish and watch them grow right in front of my eyes. Here’s to a smooth conclusion to this first experiment and smooth sailing onto the next ones!
