Cryopreservation Of Germplasm Research Articles

Cryopreservation of the Germplasm of Animals Used in Biological and Medical Research: Importance, Impact, Status, and Future Directions

Molecular genetics and developmental biology have created thousands of new strains of laboratory animals, including rodents, Drosophila, and zebrafish. This process will accelerate. A decreasing fraction can be maintained as breeding colonies; hence, the others will be lost irretrievably unless their germplasm can be cryopreserved. Because of the increasingly critical role of cryopreservation, and because of wide differences in the success with which various forms of germplasm can be cryopreserved in various species, the National Institutes of Health National Center for Research Resources held a workshop on April 10-11, 2007, titled "Achieving High-Throughput Repositories for Biomedical Germplasm Preservation." The species of concern were mouse, rat, domestic swine, rhesus monkey, and zebrafish. Our review/commentary has several purposes. The first is to summarize the status of the cryopreservation of germplasm from these species as assessed in the workshop. The second is to discuss the nature of the major underlying problems when survivals are poor or highly variable and possible ways of addressing them. Third is to emphasize the importance of a balance between fundamental and applied research in the process. Finally, we assess and comment on the factors to be considered in transferring from a base of scientific information to maximally cost-effective processes for the preservation of this germplasm in repositories. With respect to the first purpose, we discuss the three methods of preservation in use: slow equilibrium freezing, rapid nonequilibrium vitrification, and the use of intracytoplasmic sperm injection to achieve fertilization with sperm rendered nonviable by other preservation treatments. With respect to the last purpose, we comment on and concur with the workshop's recommendations that cryopreservation largely be conducted by large, centralized repositories, and that both sperm (low front-end but high rederivation costs) and embryos (high front-end but modest rederivation costs) be preserved.

CRYOPRESERVATION OF WOODY PLANTS BY AXILLARY BUD VITRIFICATION: A FIRST APPROACH WITH POPLAR

Axillary buds from in vitro-grown stock plants of White Poplar (Populus alba L.) were utilized to test the efficiency of the vitrification technique, as cryoprotective during direct freezing in liquid nitrogen. Excised axillary buds were precultured for 2 days at 5°C on a gelled MS medium, loaded for 20 min at 25°C with a cryoprotectant (2 M glycerol and 0.4 M sucrose, 1: 1), and then exposed to a concentrated vitrification solution (PVS2: 30% glycerol, 15% ethylene glycol, 15% DMSO in MS medium). After vitrification, the buds were immersed directly into liquid nitrogen for at least one hour. Successfully vitrified buds remained green after plating, and resumed growth within 2 weeks. The highest percentage of bud survival (90%) was obtained when the buds were precultured on MS medium containing 0.09 M sucrose, and vitrified by exposure to PVS2 for 60 min at 0°C. The average rate of healthy shoot development from the surviving buds amounted to about 60%. Vitrification procedure can be proposed as an useful technique for germplasm cryopreservation of woody plants.

Genetic resource banks for conserving wildlife species: justification, examples and becoming organized on a global basis

The cryopreservation of germ plasm and embryos combined with assisted reproduction play a continuing, vital role in sustaining and improving animal agriculture. It only is logical that similar types of technologies could be useful for preserving other forms of bio- and genetic-diversity, many of which are under the threat of extinction. The benefits of genetic resource banking for conservation purposes are even more profound than for domesticated livestock. In addition to preserving genetic vigor and enhancing captive propagation, these frozen repositories could provide a high level of insurance against further losses of diversity or entire species. Particularly important is that biological material could be recovered from free-living animals, stored and used without removing more individuals from native habitats. Three ongoing research projects at the National Zoological Park involving cervids, mustelids and felids are reviewed to demonstrate the potential of assisted reproduction for species preservation. Furthermore, rapidly evolving global strategies are discussed that will provide organization to the systematic collection, storage and use of germ plasm, embryos, blood products, tissue and DNA. Even given current restricted financial support for efforts, all evidence suggests that genetic resource banks will be contributing significantly to the conservation of rare wildlife species as we enter the 21st century.

Cryopreservation of Germplasm of Vegetatively Propagated Crops

Cryopreservation of Germplasm of Vegetatively Propagated Crops

Technology and prospects of cryopreservation of germplasm

Entire plants have recently been regenerated from frozen cultures of protoplasts, cells, tissues and organs and stored at super-low temperatures for various lengths of time. This suggests the possibility of utilizing cryogenic methods for the conservation of important and rare germplasm, especially of the vegetatively propagated plants, which at present do not have any satisfactory method for their preservation. In addition, the freeze preservation offers a number of significant uses and prospects; (i) tissue cultures often show chromosomal variations, nuclear and ploidy changes, and mutations. Such genetic variables and cell lines which do not occur in nature can be picked out, banked and used in response to research needs; (ii) to maintain a cell line, it has to be transferred to a fresh medium periodically; the freeze storage would suppress cell division and thus the need for subculturing is avoided; (iii) at super-low temperatures the cells are in a non-metabolic state, which delays or virtually stops the ‘ageing’ process, and thus the morphogenetic potential of cultures is retained; (iv) pathogen-free stocks could be frozen, revived and propagated when desired, this would be ideal for the international exchange of such materials; and (v) the freezing of pollen would solve some of the problems encountered with the incompatibility and pollen longevity.

A Note on Trophic Complexity and Community Stability

A Note on Trophic Complexity and Community Stability