11 July 2013
The South Australian Museum is internationally renowned for using the latest genetic science techniques, but is also home to what could be the last of the ‘gel jockeys’ — scientists using old-fashioned protein electrophoresis to create genetic profiles.
It’s this hybrid of old and new science that allows our researchers to enjoy the advantages of each method, and propels them to success on the world’s scientific stage.
Discovering a new species from two animals that look exactly the same might seem a very complicated task, but it’s all in a day’s work for one South Australian Museum researcher.
Mark Adams, the Evolutionary Biology Unit’s longest-serving research scientist, uses the process called protein electrophoresis to compare the genetic profiles of a wide range of Australian animals.
Mr Adams says that although there are many uses for this technique, including forensic and paternity testing, it is ideal for determining how many different animal species there are within one particular group.
“Protein electrophoresis is a quick way of working out how many species there are in a group of animals when you are not quite sure.”
Despite the swift and accurate results, protein electrophoresis is one of the oldest genetic techniques, and is slowly being replaced worldwide with newer types of DNA technology.
However, one of the key strengths of the Museum's Evolutionary Biology Unit is that it has world-class expertise in both old and new genetic technologies.
“Each of our many genetic procedures has its own strengths and limitations. Often the best scientific outcome is achieved when we combine both the old and the new.”
In key studies such as working with different fish species, Mr Adams has been able to gather more information that he would have using DNA testing.
“For example, five years ago one of our native freshwater fishes, the Mountain Galaxias, was thought to be just one widespread species. However, protein electrophoresis has proved that there are at least 15 different species, most of which are only found in single rivers and are therefore vulnerable to extinction.”
Fortunately, once genetic evidence establishes the presence of new species in a group, it is often possible to find subtle visible features to tell these species apart from one another. This has proved to be the case for Mountain Galaxias.
Gathering this genetic information is a sophisticated task, so Mr Adams must follow a very specific procedure to achieve the most reliable results.
First, ‘mashed’ tissue samples from each of the animals being compared are loaded side by side onto a paper-like ‘gel’ made of cellulose acetate: a simple polymer derived from wood pulp. An electric current is then applied across the gel.
The animal tissues used can come in a variety of forms such as muscle, internal organs, blood, skin, or even tail tips.
During electrophoresis, each of the many proteins present in these tissue samples move through the gel at a speed determined by its overall electric charge. This superficial similarity to a horse race explains why exponents have long been known in the trade as ‘gel jockeys’.
“Once electrophoresis is completed, I apply a stain or dye to each gel to identify the position of one selected protein, and then compare the banding patterns displayed by each individual.”
“The differences between these banding patterns reflect genetic differences in the gene that produced the protein, and these differences obey simple laws of inheritance,” Mr Adams said.
Being able to analyse the genetic profiles of a group of animals at many different protein-producing genes allows the South Australian Museum to better document Australia’s biodiversity.
“By employing these techniques, we are able to find out more about animals and provide the broader biological community with information to explore exactly what these findings mean,” Mr Adams said.
Mr Adams, one of the few Australian researchers still using protein electrophoresis, says that although modern technologies are evolving, the underlying skills for each task remain the same.
“If I was starting in this job now, I would probably be only using newer types of technology. Fortunately for me, I get to use both.”
Written by Celeste Villani.