Meeting Abstract

74.5  Saturday, Jan. 5  Analysis of myosin heavy chain (MHC) isoforms in the prehensile tails of didelphid marsupials: functional differences in arboreal versus terrestrial opossums RUPERT, J.E.*; MOREIRA, A.S.; BUTCHER, M.T.; Youngstown State University; Univ. of Costa Rica, San Jose; Youngstown State University

Little is understood about the structure and function of prehensile tails. Prehensile tails are defined as those having the ability to grasp objects and may commonly be used as an additional appendage during locomotor maneuvers. Didelphid marsupials are an excellent model to relate MHC isoform fiber type with function of caudal muscles as all opossums have a prehensile tail and, the function of the tail varies widely between terrestrial and arboreal forms. To expand on our previous study in the Virginia opossum, MHC isoforms will be determined in the tails of the terrestrial Monodelphis domestica and the arboreal Caluromys derbianus using a combination of gel electrophoresis and immunohistochemistry analyses to determine the composition of MHC isoforms expressed in the primary tail flexor muscle of each species. Preliminary results from mature M. domestica indicate the predominant expression of three MHC isoforms (1, 2A, 2X), and a relatively broad distribution of fast, oxidative hybrid fibers similar to what was previously observed in the terrestrial Virginia opossum. With the complete findings of this study we will be able to answer the following questions: 1. Is there differential expression of MHC isoforms in the prehensile tails of arboreal and terrestrial opossums and how does isoform expression relate to their locomotor habits, and 2. Does MHC isoform composition in caudal musculature change during maturation from adolescence to maturity in opossums? Supported by URC #02-12.