X-Message-Number: 19551 From: Date: Thu, 18 Jul 2002 01:21:50 EDT Subject: Mr. Nematode may be the largest... --part1_38.2b09ae11.2a67aa6e_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Olaf, In Message #19532, you ask: "I would like to know, which is the largest living thing, which has been revived from cryogenic temperatures, say - 130^ C or lower." The largest of which I am 100% confident of is the Nematode. You might be interested in reading from the following URL about this "comma" sized creature. Be sure to click on the hyperlinked "<A HREF="http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowSection&rid=cell.figgrp.d1e103308">Figure 21-39</A>" to see a rendering or two of this fine gentleman. I have cut and pasted some text from the page of the URL into this post. First though: It is possible that 21 Century Medicine, et al, may have revived some other similar creature that may have a bit more mass, but not much. Audrey Smith did a good bit of work in the 60's with hamsters, but I am far from convinced that any survivors ever got near to long-term storage temperatures. I posted several months ago on the nematode and suspended animation. I will be doing another one before too long. The upside (to get around the mass issue) is that that there are two major fluid transport systems in mammals that may be useable for distributing super-coolant (e.g., florohydrocarbons) to the cells. The blood circulatory system and the lymphatic system. Remember, it is the cells that must be protected (including their synapses, junctions, and anchors, etc., between the cells), and in order for these cells to exist at all, they must be proximate to capillaries for servicing. Yes, this implies that specimens will probably be cooled internally through the circulatory system as the means of reaching all the individual cells; however, it is certainly easier said than done. For one (not even considering the complication of having to "open-up" the specimen), consider the fact that by the time the first flow of subfreezing solution reaches the capillary level (i.e., the very cellular level of former direct nutrient, waste & gas exchange with the "blood," and now heat exchange with the coolant), it will have warmed up greatly -- thus creating the evil temperature gradient. There is no instant total body vitrification here as there is with the LN2-dunked nematode which has a far greater external surface area to mass ratio than any mammal. I believe this will eventually be done under supercomputer control, and that a litany of tricks will have to be pulled including a prior infusion of a nonlethal cryoprotectant cocktail (or two...) to prep the cells -- an ingredient of which may be a naturally occurring hormone for partially collapsing individual cellular cytoskeletons to better withstand the process. Anyway, here is the URL: http://www.ncbi.nlm.nih.gov/books/bv.fcgi?tool=bookshelf& call=bv.View..ShowSection&searchterm=automata& rid=cell.section.d1e103266#d1e103271 "For cells, as for computers, memory makes complex programs of behavior possible, and many cells together, each one stepping through its complex developmental program, can generate a very complex adult body. Some of the steps that a cell takes in the course of development are autonomous, while others are affected by signals from other cells. Thus the cells of the embryo can be likened to an array of little computers, or automata, operating in parallel and exchanging information with one another..." And: "As an adult, C. elegans is about 1 mm long and consists of only about 1000 somatic cells and 1000-2000 germ cells (exactly 959 somatic cell nuclei plus about 2000 germ cells are counted in one sex; exactly 1031 somatic cell nuclei plus about 1000 germ cells in the other) <A HREF="http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowSection&rid=cell.figgrp.d1e103308">Figure 21-39</A>. The anatomy has been reconstructed, cell by cell, by electron microscopy of serial sections. The body plan of this simple worm is fundamentally the same as that of most higher animals in that it has a roughly bilaterally symmetrical, elongate body composed of the same basic tissues (nerve, muscle, gut, skin) organized in the same basic way (mouth and brain at the anterior end, anus at the posterior). The outer body wall is composed of two layers: the protective hypodermis, or "skin," and the underlying muscular layer. A simple tube of endodermal cells forms the intestine. A second tube, located between the intestine and the body wall, constitutes the gonad; its wall is composed of somatic cells, with the germ cells inside it. C. elegans has two sexes - a hermaphrodite and a male. The hermaphrodite can be viewed most simply as a female that produces a limited number of sperm: she can reproduce either by self-fertilization, using her own sperm, or by cross-fertilization after transfer of male sperm by mating. Self-fertilization allows a single heterozygous worm to produce homozygous progeny, a special feature that helps to make C. elegans an exceptionally convenient organism for genetic studies. The relative simplicity of C. elegans anatomy is reflected in a similar simplicity of its genome. The animal has six homologous pairs of chromosomes, estimated to carry a total of 3000 "essential" genes (that is, genes in which mutations are lethal or have an easily observable effect on the phenotype) and four or five times that number of nonessential genes. The haploid genome consists of approximately 108 nucleotide pairs of DNA, which is about 20 times more than E. coli, about the same as Drosophila, and 30 times less than humans." Regards, D.C. Johnson --part1_38.2b09ae11.2a67aa6e_boundary Content-Type: text/html; charset="US-ASCII" [ AUTOMATICALLY SKIPPING HTML ENCODING! ] Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=19551