Molecular constituents of the insect presynaptic bar

I aim to characterise the components of the presynaptic bar in insects using immunocytochemistry for high resolution fluorescence microscopy and electron microscopy. Electron micrographs reveal that synapses in insects always contain a bar-shaped structure in the presynaptic terminal, and this is opposed to two or more postsynaptic elements. Because vesicles cluster around it, the bar is likely to play a significant role in organizing the process of neurotransmitter release. While the fine structural details and shape of the presynaptic bar of a variety of species have been described, nothing is known about its molecular constituents. My hypothesis is that the presynaptic bar guides vesicles to the location of exocytosis. To verify my hypothesis, I shall focus on four main questions: First, what are the molecular constituents of the presynaptic bar in mature central synapses of locusts? Focussing on sensory neurons and their interneurons in the locust, I intend to apply a panel of antibodies against synaptic molecules to elucidate the molecular constituents of organelles in their mature output synapses. Second, do synapses with different physiological characteristics differ in their molecular composition? In many insects, the presynaptic bar always has the same shape, regardless whether the neuron uses all- or none spikes to convey information (spiking neuron) or graded potentials (non-spiking neurons). To reveal molecular differences between various types of synapse, I intend to compare synapses of spiking neurons and synapses of non-spiking neurons with each other. Third, how does the presynaptic bar differ between several insect species? Whereas the presynaptic bar of locusts has a simple shape, other insects, such as bees, can have presynaptic figures made up of several columns, and flies can have an additional platform. To reveal differences in the molecular composition behind these differences in shape, I also intend to study the presynaptic zones of honeybees and of the fruit fly Drosophila. Fourth, can cell cultures be used to elucidate the molecular components of the presynaptic bar? Major advantage of studying synapses in cell culture over studies of the intact nervous system are that synaptogenesis can readily be influenced in a controlled environment. I therefore aim to obtain synapses in cell culture, monitoring the electrophysiological properties of the cells by intracellular recording. If the neurons synapse onto each other, the synapses will be studied immunocytochemically.

I aim to characterise the components of the presynaptic bar in insects using immunocytochemistry for high resolution fluorescence microscopy and electron microscopy. Electron micrographs reveal that synapses in insects always contain a bar-shaped structure in the presynaptic terminal, and this is opposed to two or more postsynaptic elements. Because vesicles cluster around it, the bar is likely to play a significant role in organizing the process of neurotransmitter release. While the fine structural details and shape of the presynaptic bar of a variety of species have been described, nothing is known about its molecular constituents. My hypothesis is that the presynaptic bar guides vesicles to the location of exocytosis. To verify my hypothesis, I shall focus on four main questions: First, what are the molecular constituents of the presynaptic bar in mature central synapses of locusts? Focussing on sensory neurons and their interneurons in the locust, I intend to apply a panel of antibodies against synaptic molecules to elucidate the molecular constituents of organelles in their mature output synapses. Second, do synapses with different physiological characteristics differ in their molecular composition? In many insects, the presynaptic bar always has the same shape, regardless whether the neuron uses all- or none spikes to convey information (spiking neuron) or graded potentials (non-spiking neurons). To reveal molecular differences between various types of synapse, I intend to compare synapses of spiking neurons and synapses of non-spiking neurons with each other. Third, how does the presynaptic bar differ between several insect species? Whereas the presynaptic bar of locusts has a simple shape, other insects, such as bees, can have presynaptic figures made up of several columns, and flies can have an additional platform. To reveal differences in the molecular composition behind these differences in shape, I also intend to study the presynaptic zones of honeybees and of the fruit fly Drosophila. Fourth, can cell cultures be used to elucidate the molecular components of the presynaptic bar? Major advantage of studying synapses in cell culture over studies of the intact nervous system are that synaptogenesis can readily be influenced in a controlled environment. I therefore aim to obtain synapses in cell culture, monitoring the electrophysiological properties of the cells by intracellular recording. If the neurons synapse onto each other, the synapses will be studied immunocytochemically.