Dr Rachel McMullan

Professional biography

Disgust

The constant risk of infection by pathogens has driven the evolution of behavioural adaptations in free-living animals that helps them to reduce pathogen contact. Such pathogen avoidance behaviours are observed across Animalia, from invertebrates to mammals. In humans, the emotion that serves to keep us away from sources of infection is disgust. This pathogen avoidance theory of disgust (PAT) is supported by strong correlations between disgust elicitors and pathogen sources. Given the many parallels between human disgust and pathogen avoidance behaviours in other animals we can begin to understand disgust through experimental studies of pathogen avoidance in animals. 

Twin studies have shown that disgust sensitivity is heritable implying the existence of ‘disgust genes’. The nematode worm Caenorhabditis elegans is routinely used as a genetic model to dissect complex behaviours. We and others have established C. elegans as a cost-effective invertebrate model of disgust that can be used to determine the function of specific genes in disgust. This model provides a platform for further investigations into the evolutionary role of disgust in host defence.

Unravelling the genetic basis of disgust-related behaviour could have numerous practical benefits. Disgust can be leveraged to improve health and influence social behaviours. It may lead to new therapeutic approaches to disgust-related pathologies such as contamination-based obsessive compulsive disorder (OCD), some phobias including blood- injection-injury phobia and arachnophobia and trypophobia. 

The effect of organophosphate exposure on neuronal function and its role in mood disorders

In collaboration with Dr Gini Harrison (Psychology)

Previous research has reported a link between exposure to organophosphate (OP) pesticides, mood disorders and suicidal behaviour. The mechanism through which OP exposure may result in mood disorders is unclear. Some researchers have suggested that they may also cause changes to serotonergic and dopaminergic pathways, which are systems involved in mood and stress regulation. Using behavioural assays in C. elegans we are studying how the long-term, low level OP exposure that has been associated with mood disorders affects neuronal development and function.

Selected Publications

2018

Sarabian, C. Curtis, V. and McMullan, R. Evolution of pathogen and parasite avoidance behaviours
Philosophical Transactions of the Royal Society B: Biological Sciences, 373, Article 20170256(1751)

Anderson, A.  and  McMullan, R. Neuronal and non-neuronal signals regulate C. elegans avoidance of contaminated food Philosophical Transactions of the Royal Society B: Biological Sciences, 373, Article 20170255(1751)

2014
Anderson A. and McMullan R. From head to tail it's a two way street for neuro-immune communication Worm 3(3) e959425
2013
Anderson A, Laurenson-Schafer H, Partridge F, Hodgkin J, McMullan R. 2013, Serotonergic Chemosensory Neurons Modify the C. elegans Immune Response by Regulating G-protein Signalling in Epithelial Cells, PLOS Pathogens Vol:9(12), e1003787
Anderson A, Kang S, McMullan R, 2013, A simple method for quantifying M. nematophilum clearance from the rectal opening of C. elegans, Worm Breeders Gazette, Vol:19 (4), Pages: 15-16 
Anderson A, McMullan E, 2013, A modified leaving assay to study pathogen avoidance, Worm Breeders Gazette, Vol:19 (4), Pages: 13-14 
2012 
Anderson A, McMullan R, G-proteins: Fighting infection on two fronts, Worm, Vol:1, ISSN:2162-4046, Pages:196-201
McMullan R, Anderson A, Nurrish S, 2012, Behavioral and Immune Responses to Infection Require G alpha q- RhoA Signaling in C. elegans, PLOS Pathogens, Vol:8, ISSN:1553-7366, Pages:e1002530-e1002530

Currently teaching on the following modules;

SK320 Infectious disease and public health

S350 Evaluating contemporary science

I am currently the engagement and enterprise lead for the School of Life Health and Chemical Sciences, a STEM ambassador and Nuffield placement provider.

I have been a competitor in "I'm a scientist get me out of here" (2015) and presented at a number of science festivals including the 2018 Northen Ireland Science Festival (Yuck, that's disgusting) and  the 2016 Cheltenham Science Festival ("The Disgust Instinct" with Valerie Curtis (London School of Hygiene and Tropical Medicine)).

I run a range of primary school outreach activities including 'how clean are your hands?' and 'yuck, that's disgusting'. 

Find out more about my recent talk at RSC Science and the Assembly 2017 here

In 2017 I organising the Royal Society Evolution of Pathogen and Parasite Avoidance meeting. You can listen to the presentations here.

Papers accompanying the meeting were published in a themed issue of Philosophical Transactions of the Royal Society B in 2018

 Member Genie (Group of elegans new investigators in europe)