Re: Cryogenic freezing of Killie eggs for species preservation

[Sarah.Wise at Colorado_EDU]

Hi all, 

I'm new to the list and don't actually keep killies -- yet -- I wrote in a 
while ago about Terranatos that I'm going to try to raise (Gary Bartell says he 
has 'em for sale, if anyone is interested).

I do work with zebrafish (ZF) and japanese medakas (a close killi relative if 
not a killi itself) at CU Boulder (where I'm working on a PhD). I'm no expert 
on cryogenics. But I have been thinking of trying to do some conservation-
oriented work on the side and am interested in this issue. The discussion got 
my brain juices going so here are some questions and ideas I have to add to the 
discussion. (Sorry it's a little long -- please delete if you reply).

Idea 1) A word of encouragement: if there are truly threatened/endangered spp. 
of killies, funding might be possible through the governments of the places 
that they are native to. The NSF, Fish and Wildlife, and Natl. Park Service in 
the U.S. all award grants yearly for conservation research proposals. Cryogenic 
facilities exist already; their equipment may be able to be shared; freezer 
space might even be able to be donated; nonprofit conservation orgs like World 
Wildlife Fund may be able to provide $$ for annual maintenance. 

Question:  Is there any summary of which spp. are threatened/endangered in the 
AKA newsletters? (Again, I'm new to this, so I apologize in advance for not 
having done any background research) If not, which spp. do you guys think are 
the most in trouble?

Idea 2) The zebrafish paper William found from the Hagedorn lab:
(http://www.biolreprod.org/cgi/content/full/59/5/1240)
indicates that work on fish embyro cryogenics is in its infancy at best -- the 
established methods have been tried and seem to have failed with ZF and 
salmonids and ornamental carp.  If current killi populations aren't in imminent 
verge of crashing it might be best to wait and see what the Hagedorn lab does 
with ZF and then try to duplicate those methods with Killis -- there's more $ 
out there and more researchers out there doing stuff with ZF, so progress is 
likely to be much faster on that front. 

Idea 3) One difference between ZF and medakas is the toughness of their chorion 
(eggshell). Medaka chorions are really really tough! This might make a 
difference for methods developed. 

Idea 4) I think there are procedures worked out already for freezing ZF sperm. 
This might be something that could be worked out quickly and immediately (for 
killi sperm). 

Idea 5) In general, working with embryos will be more difficult than working 
with sperm or other cells -- you have the yolk and the complex developmental 
machinery that have to survive the freezing process intact. From the Hagedorn 
paper (linked above) it seems like getting the yolk prepared correctly is a 
sticking point. Annual spp. could also be a whole different ball game from spp. 
that go through development immediately.

Q/Idea 6) Would cloning be a possibility in the future? If sperm or other 
tissues are kept frozen, then donor eggs from surviving killis (with their 
genetic material removed) could be used to receive the genetic material of the 
endangered spp. at any point in the future. Cloning has its problems too but if 
embryo cryogenics ultimately fails it would be a viable alternative.

All right, enough speculating for now, what do you all think? -- 

Sarah Wise
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