Dr. Christopher N Connolly

Reader

Address:

Division of Neuroscience
Mail Box 6, Level 6
Medical Research Institute
Ninewells Medical School

Phone Number:

+(44) 01382 383105

Email Address:

c.n.connolly@dundee.ac.uk

Biography

I studied for a BSc.Hons in Genetics at the University of Leeds. Following a brief period in London (Charing Cross & Westminster Hospital) developing a model of human artificial skin for research into Psoriasis, I returned to Genetics in order to obtain training in molecular genetics techniques and undertook an MSc in Molecular Biology at the University of Leicester.

From then, I have applied molecular approaches to the study of protein trafficking and developed recombinant enzymatic markers (based on Horseradish Peroxidase) to help delineate the protein transport pathways in animal cells and obtained a PhD in Cell Biology from University College London on this work. I then applied my molecular and cell biological training to investigate the biogenesis and trafficking of GABA(A) receptors at the MRC LMCB, London before arriving in Dundee in 1999 to continue these studies into receptor trafficking. In Dundee, I expanded my interests into the related 5-HT3 receptors and we are identifying trafficking mechanisms that control the delivery of new receptors to the cell surface and their subsequent removal. Our interests in both excitatory and inhibitory receptors spurred a project into the early neuronal responses to hyperactivity, such as the loss of synapses, dendritic beading and mitochondrial depolarisation/structural collapse. More recently, we have become interested in how these alterations in excitation and inhibition relate to chronic neurological conditions, in both humans and insects (honeybees and bumblebees) and we have a great interest in the impact of environmental toxins on human (and insect) health.

Research

Introduction Movie

The main focus of this laboratory is the study of the role of ligand-gated ion channel biology to the control of excitation/inhibition in neurons of the brain. Our studies concentrate on two family members of the cys-loop superfamily of ligand-gated ion channels (GABAA and 5-HT3 receptors) as well as the NMDA receptor subtype of glutamate receptors, to obtain an understanding of how such mechanisms contribute to pathological states such as epilepsy and ischaemia.

Cys-loop receptor assembly and trafficking

This research investigates the mechanisms of the Cys-loop (in particular 5-HT3 and GABAA) receptor biogenesis and how transport to the cell surface is controlled. We are using recombinant expression of novel cDNA constructs expressing chimaeric ‘living colour’ fusion proteins. We are using a combination of cell line, primary neuronal culture, organotypic culture and transgenic models to study these events.

Movie1: RIC-3a aggregation

Movie 2: RIC-3a aggregates consume ‘RIC-3 diffuse slicks’

Movie 3: RIC-3d in Golgi

Our interests include the role(s) of chaperone molecules such as RIC-3 on 5-HT3 receptor trafficking and targeting with a particular focus on how these processes are influenced by excessive exposure to serotonin. Such events may be relevant to psychosis, depression and irritable bowel syndrome. Similarly, we are interested in the responses (dynamic trafficking) of GABA(A) and glutamate (NMDA) receptors following excessive exposure to GABA and glutamate. Understanding how such a balance in excitatbility is altered may provide important information regarding alterations in behaviour and future vulnerability to neurotoxic insults.

Spreading neurotoxicity: Spreading poison versus spreading warning

We have shown previously that rapid (<10 min) neuronal morphological changes occur in response to neuronal insults as a result of NMDA receptor activation. It is not clear whether these changes are an attempt at neuronal protection or are early signs of neuronal toxicity. Interestingly, neuronal inactivation is also induced by excessive glutamate receptor activation. We are currently studying the events that follow a localised insult to monitor how these responses spread throughout neuronal networks and what impact this has to neuronal survival. We are investigating how neuronal inactivation is achieved and whether this process may be manipulated to provide better neuroprotection within the surrounding (penumbra) region of a lesion and thus limiting the spread of neurotoxicity.

Movie 4: Neuronal dendritic beading (blue), mitochondrial collapse (red) and mitochondrial depolarisation (green) in response to excess glutamate.

Movie 5: Sequential neuronal beading (blue), mitochondrial collapse (red) and mitochondrial depolarisation (green) in response to oxygen-glucose deprivation.

 

 

Dendritic beading of a hippoocampal neuron following an excitotoxic insult


Nervous System of Bees

The effects of miticides and pesticides on the nervous system of bees

 

 

Professor Neil Millar (UCL), Dr Nigel Raine (Royal Holloway), Dr Geraldine Wright (Newcastle), and Dr Christopher Connolly (Dundee). Photograph taken by Nancy Mendoza (BBSRC) at the Insect Pollinators Initiatve launch in June 2010.

 

This is a multi-disciplinary research programme (~£2M) studying the effects of miticides and pesticides on the nervous system on bees (honeybees and bumblebees). This involves research at the cellular and pathway level (University of Dundee and UCL), individual bees and whole colonies (Newcastle University and Royal Holloway University of London) and involves field studies (Scottish Beekeeper’s Association). This multi-disciplinary approach will allow us to integrate laboratory-based findings at multiple distinct levels into cohesive conclusions on the effects of these chemicals to bee health and correlate this information to the experiences of beekeepers. This high profile issue (Guardian article) and (AVAAZ.org) ) is highly controversial. To investigate this issue, this programme (2011-2015) has been funded by the Insect Pollinators Initiative as part of the Living with Environmental Change (LWEC) partnership. Further information.

Background

Honeybee decline has been identified as a major world problem and is estimated to contribute in excess of £440M to the UK economy every year. A similar decline in other native pollinators is also a major concern for our biodiversity and food security. The major identified natural threats to UK honeybees are Varroa mites and the viruses they transmit, Foul Brood diseases, Nosema and Small Hive Beetle. The control of Varroa infestation often involves the chronic exposure of a colony to miticides. These miticides target the Varroa nervous system, in particular, cholinergic neurotransmission. The central basis of our hypothesis is that chronic miticide treatment may put honeybees under significant chemical stress to the extent that they become vulnerable to otherwise sub-toxic doses of other pesticides. Honeybee pollination is important for the fertilization of a large amount of our fruit, nuts, vegetables and livestock feed. The other major pollinator of crops and native plants are bumblebees as they fly earlier in the season and are increasingly important for the pollination of UK crops such as potatoes, berries, red clover, alfalfa and greenhouse crops. The loss of bees would also have a major impact on the production of native food for wildlife, with unknown knock-on effects at the ecosystem level. While it is widely acknowledged that honeybee populations are in global decline, how the different factors are interacting to produce this decline is poorly understood. In addition to the natural threats and the chronic use of miticides, bees are also exposed to sub-toxic levels of pesticides (including herbicides and fungicides) that are vital to maintenance of crop quality and yield and so, food security. When bees are exposed to multiple pesticides, these may synergize to cause enhanced toxicity to bee populations. In order to understand the potential for such synergistic threats, we need to consider the major neuronal targets in bees for the agents used (miticides and insecticides). These targets include action potential firing (sodium channels) and the balance between excitatory (cholinergic signalling) and inhibitory (GABA and glutamate-gated chloride channels) neurotransmission (Figure 1). Perturbation of these pathways disrupts brain function in all animals, leading to locomotor, behavioural or social problems. The insect brain structure involved in bee learning (olfactory and visual) is the mushroom body. Cholinergic neurotransmission is the major excitatory pathway in this brain structure. The responses are terminated by the rapid inactivation of the released acetylcholine (ACh), by acetylcholinesterase (AChE). In insects, this excitatory activity is balanced by the inhibitory actions of chloride-gated GABA or glutamate receptors. The pharmacological manipulation of any these individual steps may have a profound effect on honeybee learning.

 

 

Given the central importance of ACh signalling in the insect brain, it has become a major target for the development of insecticides. The AChE inhibitors (eg. coumaphos [Checkmite]), have been shown to alter neuronal morphology and bee foraging behaviour. Interestingly, AChE activity decreases naturally in adult foragers and this decrease correlates with enhanced olfactory learning. Pyrethroids, (eg. fluvinate in Apistan) target neurotransmission by potentiating the voltage-gated sodium channels (Nav’s) and so prolongs action potential firing. Neonicotinoid pesticides act as partial agonists at honeybee nAChRs, but are not inactivated by AChE and may lead to prolonged receptor activation. Some neonicotinoids are more resistant to cytochrome P450 detoxicification, or generate toxic metabolites. That neonicotinoids decrease bee foraging behaviour [9] is counter-intuitive, suggesting that the role of these pesticides is inconsistent. However, the long-term consequences of the chronic exposure to neonicotinoids, such as receptor desensitization and agonist-induced receptor internalization, are unknown. To add to the confusion, imidacloprid (a neonicotinoid) exhibits “off target” activity by operating as a GABA receptor antagonist. Other pesticides, including cyclodienes and phenylpyrazoles, also inhibit GABA receptors, whereas, the ‘natural’ pesticide, thymol (the active ingredient of the miticide, Apiguard) is a GABA receptor agonist. Avermectins target the other major inhibitory receptor, the glutamate-gated chloride channel. Domestic insecticides also contain ‘synergist’ agents, e.g. piperonyl butoxide, to reduce the pyrethroid detoxification by cyctochrome P450. Despite this potential for pesticide toxicity to bees, analyses of actual doses found in pollen, bees or their honey are below toxic levels. We will investigate whether pesticides, at levels that are sub-toxic by themselves, may synergise with in-hive miticides to alter the brain activity of bees, disrupt their locomotion, ‘higher cognitive function’ (eg. learning and memory), bee communication or social interaction.

Programme

This research brings together a group of scientists with diverse but complimentary expertise in cellular and molecular neuroscience, neuroethology and behavioural ecology. Using a systems biology approach, we are performing a series of integrated interdisciplinary experiments to address these key issues. We are exploring the responses of bees to sub-lethal exposure to miticide/pesticide combinations at multiple levels of organisation: We (Connolly lab) will investigate individual neuronal responses to determine neurotoxicity, sub-lethal neuronal responses such as dendritic beading (movie 1), mitochondrial structural collapse (movie 2) and mitochondrial depolarisation (movie 3) and long term changes to receptor expression. The results of these studies will inform investigations into neurotransmission using fluorescence assays (Connolly lab) and electrophysiology, including plasticity (Harvey lab)

Movie 1 Dendritic beading of a neuron treated with a sub-lethal chemical insult

Movie 2 Mitochondrial collapse and halt to dendritic transport in a neuron treated with a sub-lethal chemical insult

Movie 3 Dendritic beading (blue), mitochondrial collapse (red) and mitochondrial depolarisation (loss of green staining) in a neuron following oxygen-glucose deprivation

Movie 4 Bumblebees (Bombus terrestris) in their nest. Courtesy of Dr Nigel Raine, RHUL

Movie 5 Bumblebees (Bombus terrestris) in a flight arena following training. Courtesy of Dr Nigel Raine, RHUL

(As part of this work Dr Raine will use Radio Frequency Identification tags to monitor bee foraging by record individual bees as they leave and re-enter the nest (Figure 2). A comparison of the difference in the weight of the bee when it returns to the nest, to when it leaves on a subsequent foraging trip, will provide information on the delivery of new resources for the colony.

 

 

Figure 2. RFID tagging of bumblebees. Courtesy of Dr Nigel Raine (RHUL)

Movie 6 The waggle dance. Worker bees communicate the location of good food supplies to other workers by dancing in a figure of eight pattern. The direction and duration of the waggle run donotes the direction and distance of the food source. For more information (http://en.wikipedia.org/wiki/Waggle_dance).

Movie 7 "Girl Power" Removal of males (non-workers) from the colony by the females (workers).

Movie 8 Bumblebee colony in laboratory at night.

An important tool for the screening of future agricultural chemicals is the availability of pest species and honeybee cell lines. This aspect of the programme is being conducted at University College London in the lab of Professor Neil Millar

The overall conclusions of this project will be related to the results of the Scottish Beekeepers Association (SBA members’ survey. This will be obtained over a 3-year period to investigate the significance of our findings to the real environment. In particular, SBA will survey, using a large number of honeybee colonies across Scotland, whether particular miticide treatment regimes are detrimental to honeybee health and performance or cause honeybees to become more vulnerable to exposure to other pesticides encountered more sporadically. From this information we hope to correlate the health, productivity and overwintering survivorship of honeybee bee colonies with respect to miticide load and potential pesticide exposure.

Publications

Teaching

I teach a course on Molecular Neurobiology to 3rd Year Pharmacology & Neuroscience students. This course cuts right across biological boundaries to relate the discovery of genes, how they are regulated, protein biogenesis, function and subcellular targeting and how these impact on neurological diseases. The course then moves into characterising the mechanism of action of disease-causing mutations (eg. Channelopathies) and finally discusses the future prospects (and problems) of rectifying such genetic faults using gene therapy techniques. The course includes the practical research methods in the study of these processes. In addition, a three week practical is run to compliment the taught lectures. This involves a full project in which the students each work on their own samples within small groups. Currently, this involves screening for the generation of gene mutations (in the lab class) followed by the recombinant expression of the mutant in tissue culture cells and finally fluorescence microscopy to identify the subcellular localisation of the mutant protein. The results of the whole class (several different mutations) are then incorporated into an integrated conclusion. This is the first experience most students have of real research (we don’t know!  As part of the ideology of the course, the assignment in this course offers the opportunity to engage with a primary research paper and an opportunity (optional) to deliver a short talk in public (the whole class).

I also deliver three hour lectures in the final (fourth) honours year on Protein trafficking in synaptic plasticity and mechanisms of neuronal excitotoxicity. I also usually supervise 1-2 lab-based honours student projects each year.

I am external examiner for the Medical Sciences MRes course for Newcastle University that includes programmes on Ageing & Health, Animal Behaviour, Biotechnology & Business Enterprise, Biosciences, Cancer, Epidemiology, Immunology, Medical & Molecular Biosciences, Medical Genetics, Molecular Microbiology, Nanomedicine, Neuroscience, Stems Cells & Regenerative Medicine, Systems Biology, Toxicology, Translational Medicine & Therapeutics and Transplantation.

 

4th Year: Module leader – “Chemical Stress” and lecture in one 3hr session.

4th Year: One 3 hr lecture in synaptic plasticity module

3rd Year: Three 1 hour lectures on GI tract and joint supervision of 1 practical class

 

PhD Supervision

Andrew Samson (2017) Spreading neurotoxicity.

Sarah Mizielinska (2009) Rapid neuronal responses to glutamate-induced ecitotoxicity and morphological changes.

Sam Matthew Greenwood (2006). Dynamic changes in neuronal morphology and mitochondrial function during excitotoxicity.

 

Conferences

  • Chair and speaker at The impact of pesticides on Bee health, 22-24th Jan 2014, Charles Darwin House, London
  • Invited speaker – Annual Symposium of CECHR, Dundee. 13th February 2013.
  • Invited seminar speaker: January 2013:  University of Southampton, Biological Sciences
  • Invited speaker: ‘Association of Independent Crop Consultants’ conference Birmingham 10-11th January 2011.
  • Invited speaker:  ‘CropWorld 2010’: Are pesticides killing our bees? London 1-3rd November 2010.
  • Organiser and speaker: 3 day Focussed meeting (Biochemical Society) “GABA(A) and glutamate receptors in health and disease” St.Andrews University July 2009.
  • Invited speaker: ‘Christopher Thompson Memorial Symposium’ (Durham 8-9th April 2008) “Glutamate excitotoxicity”
  • Meeting organiser and Chair: (Glasgow, Bioscience2007) “Pharmacological chaperones”

 Invited seminar speaker:

  • October 2011: University of Aberdeen, Institute of Medical Sciences
  • December 2010: Diagnostics & Molecular Biology, Science and Advice for Scottish Agriculture (SASA), Edinburgh
  • September 2010: School of Medical Sciences, University of St. Andrews.
  • March 2009: Sensory Biology Section, NIDCR, NIH, Bethesda, Washington DC.
  • April 2008: Centre for Neuroscience, University of Edinburgh.

Impact

News:
BBC News articles on the research and on the award of the Stephen Fry Award for Public Engagement with Research:
Bees in eastern Scotland have lower survival rate, researchers say
Neonicotinoid pesticides 'damage brains of bees'

The Scotsman: Dundee bee scientist wins Stephen Fry award
The Herald: Time for bee-friending
Compute Scotland: Bee neuroscientist awarded
Student article about pesticides: Why are bees vanishing?
Establishment of a ‘citizen science’ project to monitor honeybee disease and colony losses in Scotland. Funded by the BBSRC.
Article in BBSRC Business - Scottish beekeepers help map honeybee health
Presented written and oral evidence at Houses of Parliament:
Insects and Insecticides (transcript)

Meeting with Tavish Scott MSP Shetland (Scottish Liberal Democrats) & Scottish Wildlife Trust (Dr. M Keegan) to discuss policy changes required to respond to ongoing research. 09/01/13 Resulting in a number of questions being asked in the Scottish parliament: S4W-12316, S4W-12318, S4W-12319, S4W-12326, S4W-12327, S4W-12328, S4W-12329, S4W-12330, S4W-12336, S4W-12956, S4W-12957.

Radio:
Live radio interviews: (BBC Scotland, BBC Ireland, RTE “Moonie show”)
Bee research featured on “The now show”  Radio 4 (Fri 25th June 2010)
Recorded radio interviews: Radio Tay – 22nd June 2010; Radio 4 “You and Yours” 18th July 2011; Radio 4 “World at One” 31st January 2012

Newspaper:
Many articles (22nd June 2010) and several subsequently, including The Times, The Telegraph, The Guardian, Daily Mail, LeMonde (France 28th July 2010; includes the daily cartoon featuring the bee story).

TV:
French TV channel “France 5” News item. 20th August 2010 (Chris Connolly)

STV News: Listening to the bees (CNC) 16th September 2011

STV News: Pesticides on bee health (CNC) 09/01/13

20th April 2012. TV interview (Dr CN Connolly & GA Wright) with Landward, BBC Scotland on the bee decline: Pesticides and nutrition.

19th January 2013. Interview of Dr CN Connolly on STV: Story about Scottish Wildlife Trust's call for a moratorium on the use of neonicotinoids and the research being carried out at Dundee.