Sperm cryopreservation

Thus upon comparing the economics of the two methods, embryos and sperm, it is very apparent that the freezing of embryos is considerably more expensive due to the need for more resources for example, with a C57BL/6 background, to produce 250 two-cell embryos for cryopreservation by IVF requires >15 females. If strains are never recovered or only recovered once or twice, then the bulk of this expense remains forever frozen. In contrast, cryopreserving sperm has a low initial cost as only few animals (1-3 males) and relatively little labor and materials are required (12). It is upon recovery from sperm by in vitro fertilization (IVF) that animals and labor are used, but then only the required number animals per recovery are used as the IVF process can be scaled to produce the desired number of offspring. 

CABRITA E, ROBLES V, REBORDESos L, SARASQUETE c and HERRAEZ M p (2005) Evaluation of DNA damage in rainbow trout (Oncorhynchus mykiss) and gilthead sea bream (Sparus aurata) cryopreserved sperm. Cryobiology, 50,144—153. 

HORVATH A, MisKOLUi E, MiHALFFY s, osz K, szABO K and URBANYI B (2007) Cryopreservation of common carp (Cyprinus carpio) sperm in 1.2 and 5 ml straws and occurrence of haploids among larvae produced with cryopreserved sperm. Cryobiology, 54, 251-257. 

KOPEIKA J, KOPEIKA E, ZHANG T, RAWSON DM and HOLT W V (2004) Effect of DNA repair inhibitor (3-aminobenzamide) on genetic stabiUty of loach Misgurnus fossilis) embryos derived from cryopreserved sperm. Theriogenology, 61, 1661-1673. 

TiERSCH T R and JENKINS j A (2003) Biosecurity and regulatory considerations for transfer of cryopreserved sperm and early life stages of aquatic species, in Lee C-S and Bryen O (eds). Biosecurity in Aquaculture Production Systems Exclusion of Pathogens and Other Undesirables. Baton Rouge, LA World Aquaculture Society, 171-198. 

TIERSCH TR, GOUDIE CA and CARMICHEL GJ (1994) Cryopreservatiou of channel catfish sperm Storage in cryoprotectants, fertilization trials, and growth of channel cathsh produced with cryopreserved sperm. Transaction of the American Fisheries Society, 123, 580-586. 

YOUNG F K, WHEELER p and THORGAARD G (2009) No increase in developmental deformities or fluctuating asymmetry in rainbow trout (Oncorhynchus mykiss) produced with cryopreserved sperm. Aquaculture, 289,13-18. 

Key words Genetically modified mice, inbred mice, sperm cryopreservation, embryo cryopreservation, IVF, in vitro fertilization, genetic drift, genetic contamination. 

Ostermeier, G. C., Wiles, M. V., Farley, J. S. and Taft, R. A. (2008) Conserving, distributing and managing genetically modified mouse lines by sperm cryopreservation. PLoS ONE 3. 

Cryoprotectants are added to the culture medium in order to protect cells. Glycerine, the first cryoprotectant to be used, was discovered in the 1940s, and it was used for the cryopreservation of bovine sperm. More recently, it has been discovered that other substances such as dimethyl sulfoxide (DMSO), saccharides," and proteins also function as cryoprotectants. However, the mechanism of the cryopreservation process in each case remains unclear. In the present study, we compared DMSO and trehalose, which are cryoprotectants of different molecular sizes that may differ in their ability to pass through the cell membrane. 

Three types of cryoprotectants at various concentrations were selected DMSO (5-20 wt%), trehalose (3-17 wt%), and a mixture of trehalose (10 wt%) and methanol (8 wt%). A mixture of methanol and trehalose has been reported to be effective for the cryopreservation of salmon sperm.Therefore, this mixture was also used to check its effectiveness in the cryopreservation of neurons. 

In comparison with trehalose alone, a mixture of trehalose and methanol has been reported to be useful for the cryopreservation of salmon sperm.However, using a mixture of 10 wt% trehalose and 8 wt% methanol, no significant improvement was observed in the cell morphology (Figure 10). In future studies, in order to determine the suitability of the mixture, we have to find additives that heighten the effect of trehalose. 

CHEREGUINI O, CAL R, DREANNO C, OGIER DE BAULNY B, SUQUET M and MAISSE G (1997) (Short-term storage and cryopreservation of turbot Scophthalmus maximus) sperm, Aquatic Living Resources, vol. 10, pp. 251-255. 

Hundreds of references to sperm cryopreservation in aquatic species are available today, and this number grows each month. Many authors summarized published methods in critical reviews (see Table 3.1). Anyone attempting sperm cryopreservation for the first time is referred to these reviews as a starting point. They will find ample information on the procedure and the factors which should be considered in a given species. In this section, we will focus on the items most common in all aquatic species, and describe the steps of a cryopreservation procedure (Fig. 3.2). 

Table 3.1 Some reviews on sperm cryopreservation in aquatic species, other than in books... 

Sperm quality and cryopreservation of Characiformes, Gene banking in Viveiros and... 

Sperm cryopreservation in fish and shellfish Fish (Xiphophorus) and Need for Tiersch et al., 2007... 

Cryopreservation of sperm in marine fish Marine finfish Initial sperm quality Suquet et a/., 2000... 

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