In:
eLife, eLife Sciences Publications, Ltd, Vol. 8 ( 2019-09-17)
Abstract:
Nerve cells, also called neurons, are responsible both for sensing signals from the environment and for determining how organisms react. This means that the unique features of an animal’s nervous system underpin its characteristic behaviors. Comparing the anatomy of the nervous systems in different animals could therefore yield valuable insights into how structural and behavioral differences emerge over time. Behavioral variation often occurs even in similar-looking animals. One example is a group of microscopic worms, called nematodes. Although many nematode species exist, their overall body plans are the same, and the worms of each species contain a fixed number of cells. Despite these apparent similarities, different species of nematodes inhabit a variety of environments and may respond differently to the same signals. The main sensory organs in nematodes are called the amphid sensilla. They are used to detect chemicals, as well as other inputs from the environment such as temperature and pheromones from other nematodes. Although researchers have often speculated that the number of cells in these organs and their arrangement are broadly the same across species, their anatomy had not been studied in detail. Hong, Riebesell et al. compared the detailed structure and genetic features of the sensory systems in two distantly related species of nematode worms, Pristionchus pacificus and Caenorhabditis elegans. These two species behave in different ways, for example, P. pacificus is usually found in association with different species of beetles, while C. elegans is free-living and usually found on rotting fruit. By comparing the two, Hong, Riebesell et al. wanted to determine whether the diverse behaviors observed in the two species could be determined by differences between their sensory systems. Experiments using electron microscopy yielded several thousand high resolution images spanning the entire sensory organ. These images were then used to create detailed reconstructions of the sensory nervous system in each worm species, demonstrating that both species had the same number of sensory nerve cells, allowing one-to-one comparisons between them. Further analysis showed that while the overall structure of the neuronal connections remains the same between the two species, the neurons in P. pacificus made more diverse connections than those in C. elegans. Detailed studies of gene activity also revealed that neurons in each species switched on a slightly different group of genes, possibly indicating that each type of worm processes sensory signals in different ways. These results shed new light on how nervous systems in related species can change over time without any change in neuron count. In the future, a better understanding of these changes could link the evolution of the nervous system to the emergence of different behaviors, in both simple and more complex organisms.
Type of Medium:
Online Resource
ISSN:
2050-084X
DOI:
10.7554/eLife.47155.001
DOI:
10.7554/eLife.47155.002
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10.7554/eLife.47155.003
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10.7554/eLife.47155.004
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10.7554/eLife.47155.005
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10.7554/eLife.47155.006
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10.7554/eLife.47155.007
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10.7554/eLife.47155.008
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10.7554/eLife.47155.009
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10.7554/eLife.47155.010
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10.7554/eLife.47155.011
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10.7554/eLife.47155.012
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10.7554/eLife.47155.013
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10.7554/eLife.47155.014
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10.7554/eLife.47155.015
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10.7554/eLife.47155.016
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10.7554/eLife.47155.017
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10.7554/eLife.47155.018
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10.7554/eLife.47155.019
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10.7554/eLife.47155.020
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10.7554/eLife.47155.021
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10.7554/eLife.47155.022
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10.7554/eLife.47155.023
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10.7554/eLife.47155.024
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10.7554/eLife.47155.025
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10.7554/eLife.47155.026
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10.7554/eLife.47155.027
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10.7554/eLife.47155.028
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10.7554/eLife.47155.029
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10.7554/eLife.47155.030
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10.7554/eLife.47155.031
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10.7554/eLife.47155.032
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10.7554/eLife.47155.033
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10.7554/eLife.47155.034
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10.7554/eLife.47155.035
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10.7554/eLife.47155.036
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10.7554/eLife.47155.037
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10.7554/eLife.47155.038
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10.7554/eLife.47155.039
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10.7554/eLife.47155.040
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10.7554/eLife.47155.041
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10.7554/eLife.47155.042
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10.7554/eLife.47155.043
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10.7554/eLife.47155.044
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10.7554/eLife.47155.045
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10.7554/eLife.47155.046
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10.7554/eLife.47155.047
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10.7554/eLife.47155.048
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10.7554/eLife.47155.049
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10.7554/eLife.47155.050
DOI:
10.7554/eLife.47155.052
DOI:
10.7554/eLife.47155.053
Language:
English
Publisher:
eLife Sciences Publications, Ltd
Publication Date:
2019
detail.hit.zdb_id:
2687154-3
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