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Cryocyte
Towards the development of technologies for cryopreservation of fish oocytes

The growth of intensive aquaculture requires efficient and effective methods to preserve gametes for higher flexibility in broodstock management, genetic improvement programmes and the preservation of genetic diversity. While methods for cryopreservation of fish spermatozoa are well known, preserving important, maternally inherited genetic factors have yet to be achieved. Methods for cryopreservation of yolk-laden fish embryos remain elusive so far, but immature or mature oocytes are a specific challenge.

Objectives
The main objective is to develop methods for cryopreservation of fish oocytes while ensuring their viability (for example their maturation, fertilisation and embryonic development) after cryogenic storage and thawing. These aims will be achieved by innovative studies conducted on:
1) anticipated biological barriers for cryopreservation including the formation and structure of the vitelline envelope proteins and the process of oocyte hydration of pelagic eggs
2) the identification of specific biological markers to monitor oocyte viability after manipulation and/or cryopreservation
3) the development of oocyte in vitro incubation procedures to promote oocyte maturation, ovulation and fertilisation
4) the development of new cryopreservation technologies.
Studies on two models (the zebra fish and the gilthead sea bream) will highlight the differences between marine and freshwater species, and hydrating and non-hydrating oocytes. The results will improve fish production and increase its efficiency by the genome banking of cultured and wild species.

Progress to Date


Results
1. The primary end-product will be the development of procedures for successful
cryopreservation of fish oocytes maintaining their developmental capabilities.
2. New and powerful tools for evaluating oocyte and egg characteristics as important
diagnostic products for farmed fish and eco-toxicological studies. These will include
stage-specific molecular markers (in the form of DNA micro- or macroarrays) and protein
markers for fish oocytes and egg envelopes, biochemical assays to test the correct
enzymatic cleavage of the yolk proteins, and markers to evaluate the buoyancy of pelagic eggs.
3. Methods for obtaining oocyte maturation and ovulation in vitro that will be extremely
helpful in promoting fertilisation of naturally non-ovulating oocytes from farmed and
wild fish species.
4. The formation of cryobanks for storage of preserved oocytes for genetic improvement
programmes, for storage of important maternal genetic traits and easier transfer of
genetic material between culture locations at reduced costs and reduced danger of disease transmission. It will provide a unique methodology and greatly contribute to
improving the competitiveness of the European aquaculture industry.

Classified in FISHERIES AND AQUACULTURE

Scientist responsible for the project

Dr ESTHER LUBZENS
Tel-Shikmona Box 8030
8030 Haifa
Israel - IL

Phone: +972 48515202
Fax: +972 48511911
E-mail: esther@ocean.org.il

References

Project ID QLRT-2001-00784
Organisation ISRAEL OCEANOGRAPHIC AND LIMNOLOGICAL RESEARCH
Area 5.1.2
Start date 11 September 2002
Duration (months) 36
Total cost 2 595 000 €
Total EC contribution   1 888 600 €
Status Ongoing

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