Joffre Mercier

Professor, Biological Sciences

Office: Mackenzie Chown F 235
905 688 5550 x3832

Behavior in animals is produced by the central nervous system (CNS) and is strongly influenced by hormones that can act within the CNS, on neuromuscular targets and on visceral organs. The ultimate goal of my research is to understand the mechanisms through which hormones modulate behavior.   My research program takes an integrated approach to this problem by studying behavior at the level of whole animals, identifying hormones and neurotransmitters that underlie behavior, and uncovering the mechanisms of action of hormones and transmitters at the cellular and sub-cellular levels.   My students and I use crayfish and fruit flies as model systems for study because they have fewer nerve cells, and many of the nerve cells and even some muscle cells can be readily identified. Fruit flies provide additional advantages of a fully sequenced genome, as well as mutant and transgenic lines that can be used to test the involvement of specific genes and proteins in the functions of nerve and muscle cells.

My students and I are currently examining how neuropeptides (short chains of amino acids) modify synaptic transmission and how they influence behaviour. One of the peptides we are studying is proctolin (Arg-Tyr-Leu-Pro-Thr), which is a hormone but is also released as a co-transmitter to modify muscle contractions induced by another transmitter, glutamate. We are investigating whether or not the release of proctolin as a co-transmitter modifies its effectiveness as a hormone. We plan to do similar experiments with other neuropeptides and with some biogenic amines, such as dopamine and octopamine. At the same time, we are examining the effects of proctolin on crawling behavior in fruit fly larvae. Other work in our lab seeks to identify the intracellular signaling molecules that mediate the effects of proctolin and other modulators.

Ormerod, K.G., LePine, O.K., Shahid Bhutta, M., Jung, J.H., Tattersall, G.J., Mercier, A.J. (2016). Characterizing the physiological and behavioural roles of proctolin in Drosophila melanogaster. J. Neurophysiol., 115: 568-580.

Ormerod, K.G., Krans, J.L., Mercier, A.J.  (2015) Cell-selective modulation of the Drosophila neuromuscular system by a neuropeptide. J. Neurophysiol. 113: 1631-1643.

Milakovic, M., Klose, M., Ormerod, K.G., Mercier, A.J. (2014) Mode of action of a Drosophila FMRFamide in inducing muscle contraction. J. Exp. Biol. 217, 1725-1736.

Ormerod, K.G., Hadden, J.K., Deady, L.D., Mercier, A.J., Krans, J.L. (2013) The action of octopamine on muscles of Drosophila melanogaster larvae.  J. Neurophysiol. 110: 1984-1996.

Ruder, T., Ali, S., Ormerod, K., Brust, A., Manchadi, M.-L., Ventura, S., Undheim, E., Jackson, T., Mercier, A.J., King, G.F., Alewood, P.F., Fry, B.G.  (2013)  Functional characterization of tachykinin peptides from octopus venoms on invertebrate and vertebrate tissues. Peptides 47: 71-76.

Ormerod, K.G., Rogasevskaia, T., Coorssen, J.R., Mercier, A.J.  (2012)  Cholesterol-independent effects of methyl-ß-cyclodextrin on chemical synapses.  PLoS One 7: e36395.

Tattersall, G.J., Luebbert, J.P., LePine, O.K., Ormerod, K.G., Mercier, A.J.  (2012) Competition for temperature in crayfish is reinforced in established social hierarchies. J. Exp. Biol. 215: 1892-1904.

Cooper, A.S., Leksrisawat, B., Mercier, A.J., Cooper, R.L.  (2011)  Physiological experimentation with the crayfish hindgut:  a student laboratory exercise.  Journal of Visualized Experiments. 47. doi: 10.3791/2324.

Klose, M.K., Dason, J., Boulianne, G.L., Atwood, H.L., Mercier, A.J. (2010)  Peptide-induced modulation of synaptic transmission and escape response in Drosophila requires two G-protein coupled receptors. J. Neurosci.  30: 14724-14734.

Mercier, A.J., May, H.Y.  (2010) Recording behavioral responses to reflection in crayfish. JoVE 39., doi: 10.3791/1956.

Tinikul, Y., Mercier, A.J., Sobhon, P. (2009) Distribution of dopamine and octopamine in the central nervous system and ovary during the ovarian cycle of the giant freshwater prawn, Macrobrachium rosenbergii. Tissue and Cell, 41: 430-442.

Tinikul, Y., Soonthornsumrith, B., Phuongpetchara, I., Meeratana, P., Polijaroen, J., Duangsuwan, P., Soonklang, N., Mercier, A.J., Sobhon, P.  (2009) Effects of serotonin and dopamine on ovarian maturation and embryonic development in the giant freshwater prawn, Macrobrachium rosenbergii. Crustaceana 82: 1007-1022.

Tinikul, Y., Mercier, A.J., Sobhon, P.  (2008) Changes in the levels of serotonin and dopamine in the central nervous system and ovary during the ovarian cycle of the giant freshwater prawn, Macrobrachium rosenbergii. Gen. Comp. Endocrinol. 158: 250-258.

Clark, J., Milakovic, M., Cull, A., Klose, M.K. Mercier, A.J.  (2008) Evidence for postsynaptic modulation of muscle contraction by a Drosophila neuropeptide. Peptides 29: 1140-1149.

May, H., Mercier, A.J.  (2007) Responses of dominant and subordinate crayfish to mirrors diverge with time of pairing.  J. Exp. Biol. 210: 4428-4436.

Mercier, J., Doucet, D., Retnakaran, A.  (2007) Molecular physiology of crustacean and insect neuropeptides.  J. Pesticide Science 32:345-359.