reviving an extinct species

From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Sun May 16 1999 - 09:41:24 MDT


   Headline from the front page of the Saturday May 15,1999 issue of the
 Globe and Mail newspaper:

 "Reviving an Extinct Species

   Austrian Museum director Michael Archer examines an 1866 embryo of a
 Tasmanian Tiger, an extinct species that scientists hope to revive.
 Because the embryo was preserved in alcohol, its DNA remained intact.
 Scientists now hope to clone this embryo and others, thus bringing the
 species back to life."

   The article continues on page 2, and states that geneticists are now
 saying that this proposed species revival is not a joke, and that it
 could be done. The relevance to cryonicists is that any attempt to
 provide a lower cost alternative to current liquid nitrogen suspension
 will have to involve dehydration. None of the methods of chemical
 preservation (formaldehyde, glutaraldehyde, etc) which involve storage in
 an aqueous medium truly prevent deterioration of tissue. Only methods
 which involve dehydration (alcohol storage, anhydrobiosis, etc) can have
 any hope of offering a viable alternative to low temperature storage.
   The following is a quote regarding glycerol treated bone marrow stored
 at dry ice temperatures from (Cryobiology 65-69 1970):

  "Smears of all human bone marrow samples stored for 3 to 9 years at Dry
 Ice temperatures revealed disruption of normal cellular architecture of
 the bone marrow cells. Virtually all cells showed nuclear vacuolation,
 pyknosis, and karyolysis. The only cells with intact architecture were
 lymphocytes and cells of erythroid series. Many of these contained
 nuclear vacuoles. In addition the smears contained numerous remnants of
 cells which could not be recognized as to type. Differential counts
 revealed that on the average only 5 to 10% of cells maintained distinct
 nuclear outlines. These cells were predominantly of lymphoid and
 erythroid series with occasional eosinophils and monocytes.
  Similar changes were observed in samples of human and dog bone marrow
 stored in liquid nitrogen for 1, 2, and 3 years. However, these changes
 were found only in about 5 to 10% of cells regardless of the time of
 storage. In an occasional smear, the proportion of damaged cells reached
 as high as 20%. The changes in liquid nitrogen-stored bone marrow were
 not confined to any specific cell types.
  ....
   The observations reported in this paper indicate that very severe
 changes have taken place in bone marrow stored for over 3 years in Dry
 Ice. It has been previously shown that bone marrow cells stored under
 identical conditions for periods of up to 1 year maintain their normal
 morphology.
   However changes became apparent by 2 years and were severe by 3."



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