(last update : 01-08-2001)
Fixation of organisms
Aceton :
(Takema Fukatsu (1999) Aceton preservation : a practial technique for molecular analyses. Molecular Ecology, 8, 1935-1945)
This is the best method for fixing organisms for genetic research. It is best to store them in pure aceton, but even with 50 % water contamination in the sample, the organisms can be stored for several months at room temperature. In pure aceton, DNA can be recovered from samples that are older than 3 years.
When the the animal is used for DNA extraction, it has to be rinced first so that all of the aceton is out of the organism. Therefore rince it with destilled water and leave it in destilled water for 1 hour. When working with a single nematode : be careful : when it is transfered it into destilled water, it floats on the water, so you have to push it under water with an needle.
Carnoy solution :
This solution works fine if the organisms are stored in 100 % Carnoy, and 1/3 are animals and 2/3 is Carnoy solution in the sample. If you don't use enough Carnoy, after a few weeks, the DNA will be totally degraded.
- 6 ml ethanol (protein and DNA denaturant)
- 3 ml acetic acid glacial (DNA denaturant)
- 1 ml chloroform (assists penetration in lipid-rich tissue)
This is a good mixture for fixing organisms for genetic research. The organisms can be stored in the Carnoy solution for several months or years at room temperature.
When the the animal is used for DNA extraction, it has to be rinced first so that all of the solution is out of the organism. Therefore rince it with destilled water and leave it in destilled water for 1 hour. When working with a single nematode : be careful : when it is transfered it into destilled water, it floats on the water, so you have to push it under water with an needle.
Freezing :
An other good method to store animals is to freeze them at -80°C or in liquid nitrogen. In this conditions, the DNA stays intact for many years.
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