Year 11 and 12 Biology Students visit The University of Melbourne

On the 18th of July 2019, our Year 11 and 12 (Units 3 & 4) Biology students went on an exciting excursion to the Bioscience Department at The University of Melbourne. We started our experimental investigation at 9:40 am and completed it at 12 pm. Practical investigations were carried out in the Genetics Laboratory and the topics covered were linked to the new approach especially applying knowledge and developing thinking skills in genetics. The teaching session was very well organised and relevant to our current area of study on gene technology. The girls were engaged throughout the whole presentation and enjoyed the technique very much. There was a good mix of hands-on and listening time.

The following activities provided an insight into how genes coding for resistance to an antibiotic are transferred between bacteria and how the change in allele frequency resulted over many generations in Drosophila melanogaster.

OUTLINE OF THE EXPERIMENTS

Experiment 1: An investigation into how antibiotic resistance may be transferred

BACKGROUND

The discovery of antibiotics in the mid-twentieth century revolutionised medicine and saved millions of lives, enabling treatment of previously fatal infectious diseases and development of more successful surgical treatments. However, since this time, resistance to virtually every antibiotic has been documented, a problem that has largely originated from the overuse and misuse of antibiotics in human and animal health. Across the world, antibiotics have been overprescribed and also used in animal feed as growth promoters in intensive agricultural practices. Continued low-level exposure to antibiotics selects for resistant populations of bacteria which may then be able to spread through the environment and into humans.

The problems caused by the emergence and spread of resistance to antibiotics has been recognised by governments across the world and in June 2015, the Australian government released the first national Antimicrobial Resistance Strategy 2015-2019 aimed at increasing awareness posed by the threat of antibiotic resistance and promoting appropriate use in the animal and human health disciplines.

Experiment 2: Evidence for evolutionary change using Drosophila melanogaster

The aim of this practical was to investigate how a mutation in Drosophila melanogaster results in a difference in fitness of the fly and a change in phenotypes and allele frequencies over time.

BACKGROUND

The vinegar fly, Drosophila melanogaster, is a species that has been used extensively in studies on heredity. Vinegar flies may be seen at home around the compost bin or near fruit which is rotting. Drosophila's small size and ease of handling and breeding in the laboratory are factors contributing to its usefulness, but its most important feature to a geneticist is its relatively short generation time - 10 days at 25 degrees Celsius and a large number of offspring in each generation, and many different well known gene mutations. The fly most frequently encountered in natural populations is referred to as the 'wild-type’ and is used as a standard for comparison of mutant types.

Students were supplied with a tube of flies representing one of the 5 generations. They anaesthetised the flies in the tube using CO2. The flies remained inactive while the CO2 was flowing. The flies were sorted into wild type (oval winged) and vestigial winged and students collected the evolutionary data explaining the changes in allele frequency.