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16 October 2020 | Story Leonie Bolleurs | Photo Supplied
Kyla Dooley, runner-up in this year’s Three-minute thesis competition, wants to pursue a career working alongside police enforcement, using her knowledge of forensics to solve criminal cases and convict perpetrators.

When rapes and sexual assaults are committed, DNA evidence can play a large role in convicting the offenders. DNA evidence collected from sexual crimes can, according to Kyla Dooley, often be tricky to analyse.

Kyla has just completed her master’s degree, specialising in Forensic Genetics, at the University of the Free State (UFS). She not only thrives in this field – graduating at the top of the Faculty of Natural and Agricultural Sciences in 2018 when she was awarded the Dean’s Medal – but her work also brought her the runner-up position in this year’s Three-minute thesis competition. 

She talked about her research on the use of male-specific DNA in the analysis of DNA evidence collected after crimes of a sexual nature have been committed.

Explaining her research, Kyla elaborates: “In most cases, the victim is female, while the offender is male. Therefore, the evidence is often a mixture of male and female DNA and this can make it difficult to analyse the male DNA and match it to a male suspect.”

She believes the solution to this is to target male-specific DNA in analysis. “This eliminates all female DNA and simplifies the process,” says Kyla.

“Unfortunately, male-specific DNA technology is not currently used in South Africa, because the DNA regions tested to date haven’t shown much success in distinguishing between males in our population,” Kyla points out.

“The goal is now to use DNA evidence, to match it to a suspect, and have the confidence that it came from him and only him. Or else defence lawyers could argue that it came from someone else in the population,” she says.

Improving DNA evidence

Therefore, Kyla’s research focused on evaluating a new group of male-specific DNA regions, which are to be tested yet, to see if it would be a viable option for use in South Africa. 

“I achieved this by collecting DNA samples from men on campus, processing them to obtain DNA profiles, and then determining how well these regions can distinguish between the men. The results of my research demonstrate the potential of these DNA regions to improve the use of DNA evidence when investigating sexual assaults in South Africa,” says Kyla.

She believes her study can play a role in increasing the conviction rate of sexual offenders, which could lead to a reduction in South Africa’s alarmingly high rape statistic. 

“Everyone in South Africa is affected by this horrific crime in some way or another, so the benefits of this would be widespread,” she says.

Solving crimes

Although Kyla will one day pursue further studies, she is ready for the next stage in her life. “I am in the process of applying for jobs and getting ready to dive into the real world. I’ll definitely be pursuing a career working alongside police enforcement to solve criminal cases and convict perpetrators of such crimes. Working for the NYPD in the USA or Scotland Yard in the UK is the ultimate dream job,” she says.

“I chose my field not only because the forensics world absolutely fascinates me, but also because I want to make a difference. I want to play a role in getting justice for those affected by violent crimes. One simple process in a forensic scientist’s everyday routine could be a life changer for a victim of crime,” believes Kyla.

 

 


News Archive

Research eradicates bacteria from avocado facility
2017-01-17

 Description: Listeria monocytogenes Tags: Listeria monocytogenes

Listeria monocytogenes as seen under an electron
microscope. The photo was taken with a transmission
electron microscope at the microscopy unit of the UFS.
Bacteriophages (lollipop-like structures) can be seen
next to the bacterial cells.
Photo: Supplied

“The aim of my project was to identify and characterise the contamination problem in an avocado-processing facility and then to find a solution,” said Dr Amy Strydom, postdoctoral fellow in the Department of Microbial Biochemical and Food Biotechnology at the University of the Free State (UFS).

Her PhD, “Control of Listeria monocytogenes in an Avocado-processing Facility”, aimed to identify and characterise the contamination problem in a facility where avocados were processed into guacamole. Dr Strydom completed her MSc in food science in 2009 at Stellenbosch University and this was the catalyst for her starting her PhD in microbiology in 2012 at the UFS. The research was conducted over a period of four years and she graduated in 2016. The research project was funded by the National Research Foundation.

The opportunity to work closely with the food industry further motivated Dr Strydom to conduct her research. The research has made a significant contribution to a food producer (avocado facility) that will sell products that are not contaminated with any pathogens. The public will then buy food that is safe for human consumption.


What is Listeria monocytogenes?

Listeria monocytogenes is a food-borne pathogenic bacterium. When a food product is contaminated with L. monocytogenes, it will not be altered in ways that are obvious to the consumer, such as taste and smell. When ingested, however, it can cause a wide range of illnesses in people with impaired immune systems. “Risk groups include newborn babies, the elderly, and people suffering from diseases that weaken their immune systems,” Dr Strydom said. The processing adjustments based on her findings resulted in decreased numbers of Listeria in the facility.

The bacteria can also survive and grow at refrigeration temperatures, making them dangerous food pathogens, organisms which can cause illnesses [in humans]. Dr Strydom worked closely with the facility and developed an in-house monitoring system by means of which the facility could test their products and the processing environment. She also evaluated bacteriophages as a biological control agent in the processing facility. Bacteriophages are viruses that can only infect specific strains of bacteria. Despite bacteriophage products specifically intended for the use of controlling L. monocytogenes being commercially available in the food industry, Dr Strydom found that only 26% of the L. monocytogenes population in the facility was destroyed by the ListexP100TM product. “I concluded that the genetic diversity of the bacteria in the facility was too high and that the bacteriophages could not be used as a control measure. However, there is much we do not understand about bacteriophages, and with a few adjustments, we might be able to use them in the food industry.”

Microbiological and molecular characterisation of L. monocytogenes

The bacteria were isolated and purified using basic microbiological culturing. Characterisation was done based on specific genes present in the bacterial genome. “I amplified these genes with polymerase chain reaction (PCR), using various primers targeting these specific genes,” Dr Strydom said. Some amplification results were analysed with a subsequent restriction digestion where the genes were cut in specific areas with enzymes to create fragments. The lengths of these fragments can be used to differentiate between strains. “I also compared the whole genomes of some of the bacterial strains.” The bacteriophages were then isolated from waste water samples at the facility using the isolated bacterial strains. “However, I was not able to isolate a bacteriophage that could infect the bacteria in the facility.

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