Procedure for studying population genetic aspects of marine organisms using biochemical techniques

Abstract

Starch gel electrophoresis is being used in laboratory at the NIO for separation of enzymes (isozymes/allozymes), general proteins and hemoglobins of fish species. This technique is also applicable to other organisms. Starch gel has been found to be the best general media for isozyme studies and it also serves effectively for large scale screening which is very essential for population studies. In order to carry out starch gel electrophoresis, a starch gel must first be prepared in the laboratory from powdered starch. The process consists of making a solution of starch, cooling it, and then pouring it into a mould called a starch gel tray. As the starch solution cools, it solidifies into a gel which is used for electrophoresis. The width of the starch gel tray will vary according to the needs of the investigator. In general, the wider the tray, the larger the number of samples that can be studied on the same gel. The depth of the starch gel tray determines the thickness of the resulting gel. The thicker it is, the more easily it can be cut into a number of horizontal slices after electrophoresis, and the larger the number of enzymes which can be analyzed after a single electrophoretic run. However, the gel must not be so thick that it becomes too warm in its interior during electrophoresis. Undue heating may cause loss of enzyme activity and distortion of patterns. After the gel has cooled for about 2 hrs at room temperature, it is placed in a refrigerator (4 degrees C) for about 20 minutes. It can then be used. One difficulty often encountered with gels that have not cooled for very long is that they stick to the gel plate. This difficulty can be overcome if the gels are prepared the day before and allowed to mature overnight at 4 degrees C