| Abstract: | Recent progress in the investigation of limb malformations in free-living frogs has underlined the wide range in the types of limb malformations and the apparent spatiotemporal clustering of their occurrence. Here, we review the current understanding of normal and abnormal vertebrate limb development and regeneration and discuss some of the molecular events that may bring about limb malformation. Consideration of the differences between limb development and regeneration in amphibians has led us to the hypothesis that some of the observed limb malformations come about through misdirected regeneration. We report the results of a pilot study that supports this hypothesis. In this study, the distal aspect of the right hindlimb buds of X. laevis tadpoles was amputated at the pre-foot paddle stage. The tadpoles were raised in water from a pond in Minnesota at which 7% of surveyed newly metamorphosed feral frogs had malformations. Six percent (6 of 100) of the right limbs of the tadpoles raised in pond water developed abnormally. One truncated right limb was the only malformation in the control group, which was raised in dechlorinated municipal water. All unamputated limbs developed normally in both groups. Three major factors under consideration for effecting the limb malformations are discussed. These factors include environmental chemicals (primarily agrichemicals), encysted larvae (metacercariae) of trematode parasites, and increased levels of ultraviolet light. Emphasis is placed on the necessary intersection of environmental stressors and developmental events to bring about the specific malformations that are observed in free-living frog populations. |
| Genre: | Article |
| ProdID: | 1003668 |
| Citation Author: | Loeffler, I. K.; Stocum, D. L.; Fallon, J. F.; Meteyer, C. U. |
| Citation Contributing Office: | National Wildlife Health Center |
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| Citation End Page: | 245 |
| Citation Issue: | 5 |
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| Citation Language: | English |
| Citation Larger Work Title: | The Anatomical Record Part B: The New Anatomist |
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| Citation Number Of Pages: | 18 |
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| Citation Phsyical Description: | p. 228-245 |
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| Citation Search Results Text: | Leaping lopsided: a review of the current hypotheses regarding etiologies of limb malformations in frogs; 2001; Article; Journal; The Anatomical Record Part B: The New Anatomist; Loeffler, I. K.; Stocum, D. L.; Fallon, J. F.; Meteyer, C. U. |
| Citation Start Page: | 228 |
| Citation Volume: | 265 |
| Citation Year: | 2001 |
| Type: | citation/reference |
| Text: | Leaping lopsided: a review of the current hypotheses regarding etiologies of limb malformations in frogs; 2001; Article; Journal; The Anatomical Record Part B: The New Anatomist; Loeffler, I. K.; Stocum, D. L.; Fallon, J. F.; Meteyer, C. U. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (INDEX PAGE): | http://www3.interscience.wiley.com/journal/86510968/abstract |
| Date Other: | Mon, 1 Jan 2001 00:00 -0600 |
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