This review is focused on the applications of genome cryobanking of aquatic species including freshwater and marine fish, as well as invertebrates. It also reviews the latest advances in cryobanking of model species, widely used by the scientific community worldwide, because of their applications in several fields. The state of the art of cryopreservation of different cellular types (sperm, oocytes, embryos, somatic cells and primordial germ cells or early spermatogonia) is discussed focusing on the advantages and disadvantages of each procedure according to different applications. A special review on the need of standardization of protocols has also been carried out. In summary, this comprehensive review provides information on the practical details of applications of genome cryobanking in a range of aquatic species worldwide, including the cryobanks established in Europe, USA, Brazil, Australia and New Zealand, the species and type of cells that constitute these banks and the utilization of the samples preserved. Statement of relevance This review compiles the last advances on germplasm cryobanking of freshwater and marine fish species and invertebrates, with high value for commercial aquaculture or conservation. It is reviewed the most promising cryopreservation protocols for different cell types, embryos and larvae that could be applied in programs for genetic improvement, broodstock management or conservation of stocks to guarantee culture production.

In free-spawning invertebrates sperm-egg incompatibility is a barrier to mating between species, and divergence of gamete recognition proteins (GRPs) can result in reproductive isolation. Of interest are processes that create reproductive protein diversity within species, because intraspecific variants are potentially involved in mate choice and early speciation. Sperm acrosomes of the Pacific oyster Crassostrea gigas contain the protein bindin that bonds sperm to egg during fertilization. Oyster bindin is a singlecopy gene encoding a diversity of protein variants. Oyster bindins have a conserved N-terminal region followed by one to five tandem fucose-binding lectin (F-lectin) domains. These repeats have diversified by positive selection at eight sites clustered on the F-lectin's fucose binding face. Additional bindin variants result from recombination in an intron in each F-lectin repeat. Males also express alternatively spliced bindin cDNAs with one to five repeats, but typically translate only one or two isoforms into protein. Thus, positive selection, alternative splicing, and recombination can create thousands of bindin variants within C. gigas. Models of sexual conflict predict high male diversity when females are diverse and sexual conflict is strong. The amount of intraspecific polymorphism in male GRPs may be a consequence of the relative efficiency of local (molecular recognition) and global (electrical, cortical, and physical) polyspermy blocks that operate during fertilization.combinatorial diversity ͉ F-type lectin ͉ fertilization ͉ polymorphism ͉ sperm-egg binding S election shapes molecular variation in at least two ways: by modifying the rate at which mutations are fixed or eliminated and by favoring gene architectures and mutational mechanisms that increase protein diversity. These two responses to selection are evident in many biological recognition proteins including those of host-parasite interaction, self-incompatibility, and development (1-3). These modular gene architectures allow combinatorial mechanisms like recombination and alternative splicing to produce hundreds or thousand of protein variants from a single gene. The complexity of these diversity-generating mechanisms suggests that they are evolved responses to sustained selection favoring protein diversity.Gamete-recognition proteins (GRPs) mediating sperm-egg recognition and fusion are foremost examples of selection causing rapid protein evolution, perhaps because of a sexual conflict between sperm and egg over optimal fertilization rate (4). Because GRP divergence could initiate reproductive isolation between incipient species, studying mechanisms that create intraspecific variation is key to understanding how GRPs and the selective pressures that cause their divergence contribute to speciation. The amount of polymorphism observed in GRPs varies considerably (5). Abalone sperm lysin monomorphism (6) is contrasted by considerable polymorphism within and between populations in mussel sperm lysin-M7 (7, 8) and sea urchin sperm bindin...

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