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Loer, C. M.

Publications and source records attributed to Loer, C. M..

2 recordsLinked to original sources

Identity and functions of monoaminergic neurons in the predatory nematode Pristionchus pacificus reveal nervous system conservation and divergence

Changes in neurotransmitter usage in homologous neurons may drive evolutionary adaptations in neural circuits across animal phylogeny. The predatory nematode Pristionchus pacificus can be used as a model system to examine nervous system evolution by comparing neurotransmitter expression with that of C. elegans and other nematodes. Here we characterize P. pacificus neurotransmitter expression and function in specific neurons, focusing on its complete set of monoaminergic neurons. We discover patterns of conservation as well as novelties. We examine the roles of monoamines in specific behaviors using neurotransmitter synthesis and vesicular transporter mutants, finding possible differences in the control of host-finding and dispersal behavior.

neuroscience↗

Comparative connectomics of two distantly related nematode species reveals patterns of nervous system evolution

Understanding the evolution of the bilaterian brain requires a detailed exploration of the precise nature of cellular and subcellular differences between related brains. To define the anatomical substrates of evolutionary change in the nervous system, we undertook an electron micrographic reconstruction of the brain of the predatory nematode Pristionchus pacificus. A comparison with the brain of Caenorhabditis elegans, which diverged at least 100 million years ago, reveals a conserved nematode core connectome and a wide range of specific substrates of evolutionary change. These changes include differences in neuronal cell death, neuronal cell position, axo-dendritic projection patterns and many changes in synaptic connectivity of homologous neurons that display no obvious changes in overall neurite morphology and projection patterns. Arguing against specific hot spots of evolutionary change, connectivity differences are distributed throughout the nervous system and extend to glia as well. We observed examples of apparent circuit drift, where changes in morphology and connectivity of a neuron do not appear to alter its behavioral output. In conclusion, our comprehensive comparison of distantly related nematode species provides novel vistas on patterns of conservation as well as the substrates of evolutionary change in the brain that span multiple organizational levels.

neuroscience↗