Cytogenetics: Adding to the Frozen Zoo

A rare tuatara, above, and tuatara fibroblast cells.

A rare tuatara, above, and tuatara fibroblast cells.

We have had another exciting year in the Genetics Division at the San Diego Zoo Institute for Conservation Research. The cytogenetic team has established 245 fibroblast cell cultures that we have added to the Frozen Zoo®, including 39 new species. These new species consist of 25 bird, 6 mammal, 3 reptile, and 5 amphibian cell lines. One of these is a Brother’s Island tuatara Sphenodon guntheri cell line. This cell line is the only representative for the taxonomic order Sphenodontia that is now in the Frozen Zoo! It is very exciting to have these unique cells frozen, and, at anytime, we can thaw them and grow additional fibroblast cells. It is so wonderful to know that this species’ DNA will be saved for the future.

Two other important additions to the Frozen Zoo this year were the endangered boreal toad Bufo boreas boreas and the endangered mountain yellow-legged frog Rana muscosa cell cultures. Both of these species have been in decline in part due to chytrid fungus, a disease that has effected many amphibian populations. Therefore, to have genetic material saved on them is vital. A couple of the mammals that we added were the Pacific pocket mouse Perognathus longimembris pacificus and the Catalina Island fox Urocyon littoralis catalinae; both of these came from small isolated populations, so it is crucial to save their DNA for future studies. All of these new additions can help us better understand the Earth’s biodiversity.

An eastern common ringtail possum, above, and its karyotype.

An eastern common ringtail possum, above, and its karyotype.

In addition to establishing the cell cultures that go into the Frozen Zoo, we also do karyotypes (chromosomal maps) on every cell line. This will usually help us confirm the species and sex of the individual and also if there are any chromosomal abnormalities. This year, we created karyotypes on 178 individual animals consisting of 109 species. This includes 37 species that we have never karyotyped before. We have karyotyped a wide range of animals this year, like the eastern common ringtail possum Pseudocheirus peregrines with a diploid number (number of chromosomes) of 2n=20 and southern pudu Pudu puda, which has 70 chromosomes. It is always fun in the Genetics Lab, because you never know what species you could be working on next. What species would you like to see represented in the Frozen Zoo?

Suellen Charter is a research coordinator for the San Diego Zoo Institute for Conservation Research. Read her previous post, Carpooling Safari.

Still quiet here.sas

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