2012/727 Visit by Dr. Standish K. Allen Jr. from the Virginia Institute of Marine Science

By Penny Miller

Fluorescent in situ hybridisation (FISH) is a genetic technique that involves fluorescently labelling chromosomes so that each can be identified individually under a high powered microscope. FISH could be an important tool for detecting the aneuploid frequency in tetraploid oyster populations. This is important because a decrease in tetraploid genetic stability could potentially reduce the efficiency of breeding programs and may have carry over impacts on the triploid commercial product.

The PhD student travelled to Canberra to work with Tariq Ezaz of the University of Canberra on troubleshooting her FISH protocol to work on Pacific Oysters. Eventually, the protocol worked, but not consistently or at a strong enough level for chromosomes to be individually identified. It was determined that, due to their small size and weak signals, fluorescently labelled microsatellites are not a reliable method for karyotyping oysters, particularly polyploids where chromosomes tend to overlap. A different probe (PNA) was also trialled. Again this was inconsistent, but the signals were stronger than the microsatellites. This probe is worth mapping and further investigation, however, time, money and sampling constraints prevented any additional study.

Given the limited success of the FISH work, Dr Allen's visit was used to improve analysis and write up of two other studies into Pacific Oysters.