Scanning electron microscopic analysis of spontaneous and UV-induced abnormal segment patterns in Chironomus samoensis (Diptera,Chironomidae) |
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Authors: | Jean Percy Kristen L Kuhn Klaus Kalthoff |
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Institution: | (1) Department of Agriculture, Forest Pest Management Institute, 1219 Queen St. E., Sault Ste. Marie, Ontario, Canada;(2) Center for Developmental Biology, Department of Zoology, The University of Texas, 78712 Austin, TX, USA |
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Abstract: | Summary The embryonic body pattern of Chironomus samoensis, as well as other chironomids, can be altered dramatically by irradiating their eggs with ultraviolet light (UV). Anterior UV irradiation leads to the formation of double abdomen embryos whose anterior segments are replaced by posterior segments with reversed polarity. Most double abdomens are symmetrical showing a mirror image duplication of the posterior six or seven segments. However, in some cases the anterior end of the double abdomen is shorter, and comprises fewer segments, than its posterior counterpart. These asymmetries range from moderate to extreme. They involve the juxtaposition, at the plane of polarity reversal, of disparate segments. The same range of symmetrical and asymmetrical double abdomens is also formed spontaneously in an apparently mutant strain of C. samoensis. There are striking similarities between this natural variant and the Drosophila melanogaster mutant bicaudal which are also discussed with respect to models of embryonic pattern formation. |
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Keywords: | Embryogenesis Maternal effect mutant Morphogenetic determinant Pattern formation UV irradiation |
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