How Freezing Fish Sperm Uncovers Dad's Gene Effects

Jim Crocker
18th March, 2024

Image Source: Natural Science News, 2024

Key Findings

In a study with Eurasian perch, cryopreserved sperm led to offspring with higher final weight
Cryopreservation upregulated genes in offspring that improved their eyesight
Better eyesight from these genes likely helped the offspring forage more efficiently

In the realm of aquaculture, the genetic and epigenetic integrity of fish spermatozoa is of paramount importance, as it influences not only the immediate offspring but also the future of entire fish populations. Researchers from the Polish Academy of Sciences have conducted a groundbreaking study^[1] that sheds light on the potential benefits of sperm cryopreservation, a common practice used to store genetic material for future use. Cryopreservation involves freezing sperm cells to preserve them for long periods. This technique is not without its challenges, as the freezing and thawing process can damage the cells and alter their functions. Previous studies have shown that cryopreservation can affect sperm quality and subsequently the development of embryos, particularly in species like rainbow trout and channel catfish^[2]^[3]. For example, in rainbow trout, different cryoprotectants can lead to variable outcomes in sperm functionality and DNA methylation, a form of epigenetic change that can be passed on to offspring^[2]. In channel catfish, cryopreservation has been linked to increased oxidative stress and changes in gene expression in sperm, which could impact embryo development^[3]. The Polish Academy of Sciences' study took these concerns a step further by investigating how cryopreservation affects paternal-effect-genes (PEGs), which are genes in the sperm that can influence traits in the progeny. Using Eurasian perch as a model organism, the researchers compared the offspring of eggs fertilized with fresh sperm to those fertilized with cryopreserved sperm. Surprisingly, the study found that most traits in the offspring were similar between the two groups. However, there was a notable exception: the final weight of the larvae was higher in the group that came from cryopreserved sperm. This suggests that cryopreservation might not only preserve sperm but could also select for sperm with certain beneficial characteristics. Delving into the molecular effects, the researchers discovered that cryopreservation upregulated most PEGs in the offspring. This upregulation led to an unexpected advantage: the larvae from the cryopreserved group exhibited better eyesight, which likely contributed to their increased weight gain due to more efficient foraging. This discovery is significant as it points to the paternal genome's influence on the visual system development in fish, with genes like pde6g, opn1lw1, and rbp4l identified as new PEGs. The study's findings are not only intriguing for the field of genetics but also for aquaculture practices. By understanding the effects of cryopreservation on PEGs, breeders could potentially improve the quality of fish stocks. Moreover, the identification of new PEGs related to visual perception opens new avenues for research into how paternal factors influence offspring traits. While this study focused on a specific species, the implications could be far-reaching. It could inform cryopreservation techniques in other fish species, many of which are vital for commercial aquaculture. For instance, the triploidisation process used in rainbow trout to induce sterility involves manipulating the genetic makeup of the fish^[4]. Understanding how cryopreservation affects PEGs could help manage the unintended consequences of such genetic interventions. Furthermore, the comprehensive databases like the EMBL-EBI Expression Atlas^[5] provide a valuable resource for researchers looking to explore gene expression patterns across different species and conditions. This can complement studies like the one conducted by the Polish Academy of Sciences, offering a broader context for the observed changes in gene expression due to cryopreservation. In conclusion, the study by the Polish Academy of Sciences opens up a new perspective on the role of paternal genetic material in the development of fish offspring. By highlighting the potential positive effects of sperm cryopreservation, it challenges preconceived notions about the process and provides valuable insights for future aquaculture practices.

Biotech Genetics Marine Biology

References

Main Study

1) Paternal-effect-genes revealed through sperm cryopreservation in Perca fluviatilis.

Published 16th March, 2024

https://doi.org/10.1038/s41598-024-56971-w

Related Studies

2) Cryopreservation effect on DNA methylation profile in rainbow trout spermatozoa.

https://doi.org/10.1038/s41598-023-44803-2

3) Transcriptome Analysis Reveals Key Gene Expression Changes in Blue Catfish Sperm in Response to Cryopreservation.

https://doi.org/10.3390/ijms23147618

4) Ovarian transcriptome analysis of diploid and triploid rainbow trout revealed new pathways related to gonadal development and fertility.

https://doi.org/10.1016/j.animal.2022.100594

5) Expression Atlas update: gene and protein expression in multiple species.

https://doi.org/10.1093/nar/gkab1030

Key Findings

References

Main Study

Related Studies

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