Lyophilization preserving tissue

The collection of plant tissue is quite different from animal tissue collection. The discussion of collection of plant and animal tissue by Dessauer et al.2S is detailed and helpful. However, the recommendations for procedures unique to plant tissue collection are somewhat misleading and outdated, especially when tropical collections are involved. Plant tissue can now be collected and transported as either fresh tissue (leaves and/or shoot cuttings) or preserved tissue the latter either as cryopreserved tissue (liquid nitrogen or dry ice) or as dried tissue (air-dried, herbarium-dried, lyophilized, or chemically dried). Ambient-temperature liquid chemical preservation techniques (such as those routinely done for herbarium plant specimens in the tropics) so far have been ineffective in maintaining adequate yields of high-quality DNA.15 It should be stressed again that the manner of collecting plant tissue is dictated by several other factors what macromolecule (DNA, RNA, or isozymes) will be examined, what type of nucleic acid extraction method will be used (or, more impor-... 

So far, our description of preservation has focused mostly on proteins or enzymes in solution. Less is known about the cryopreservation and lyophilization of entire cells or tissues, which is one of the ultimate objectives of our work. While many of the ideas or hypotheses described above in the context of proteins are also applicable to cells or tissue, the inherent complexity of such systems poses important, additional challenges. In particular, the role played by cell membranes must be taken into consideration. 

Water is crucial to maintain the integrity and the permeability of biological membranes. Therefore, the preservation processes by which water is extracted from cells and tissues, such as dehydration, lyophilization, or desiccation, need careful analysis with regard to the interaction of water with membrane groups and the interfacial properties derived from it. 

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