The University of Prince Edward Island Atlantic Veterinary College

Lampreys and hagfishes are living representatives of a group of jawless fishes, which were common 500 million years ago.  As the most ancient vertebrates alive today and are important in studies of molecular evolution and in investigations to determine vertebrate features which are primitive and those that have arisen subsequent to the origin of the vertebrates.

The skeleton of the hagfishes and lampreys is cartilaginous. Collagen is the major structural protein of  most cartilages in the jawed vertebrates.  Our lab has shown that the cartilages of hagfishes and lampreys lack collagen and therefore may be termed  non-collagenous cartilages.  The annular (mouth), piston (tongue) and trabecular (neurocranial) cartilages of the sea lamprey (Petromyzon marinus) are composed primarily of a previously unrecognized but major structural protein of unique composition which we termed lamprin. Myxinin is an unusual structural protein of unique composition constituting the major structural protein of  the lingual cartilage in the Atlantic hagfish (Myxine glutinosa).

Lamprin has been cloned, sequenced and partially characterized (1) and  the spatial and temporal distribution of lamprin transcripts during chondrogenesis of  the trabecular cartilage in embryonic lamprey  has been determined (2). We have defined the ultrastructural features of chondrogenesis of  lamprin-based  trabecular cartilage in  lamprey embryos (3) and shown evidence identifying two different non-collagenous cartilages in  lamprey designated as cranial (those composed of lamprin) and branchial (4).  Both lamprin and branchial cartilage matrix protein share similarities with vertebrate elastins (5).

    At least two types of non-collagenous cartilages have been identified in hagfish, designated as hard and soft, each with a distinct matrix protein (6).  Myxinin is found in hard cartilages.

     Preliminary investigations of the endoskeletal elements of the gills in the horseshoe crab indicate that this cartilaginous tissue contains a non-collagenous, fibrillar matrix protein which could be a related protein (7).

    The structure and organization of the lamprin genes have been determined (8) and we have defined the morphological aspects of branchial cartilage chondrogenesis during lamprey embryogenesis (9).  Recently we have expanded our understanding of lamprey development through the analysis of key external and internal developmental events in sea lamprey embryos of different chronological ages (10).

    The physical properties of lamprey cartilages are being studied in collaboration with  Dr. M.E. DeMont  (Department of Biology, St. Francis Xavier University).  We have compared the equilibrium stress-relaxation behaviour of lamprey and bovine cartilages and found that despite mechanical and functional differences, lamprey cranial and branchial cartilages demonstrate equilibrium stiffnesses and relaxation properties similar to those of mammalian cartilages (11).

    Using morphological, biochemical, molecular and biomechanical approaches we continue to investigate the matrix proteins of lamprey, hagfish and horseshoe crab cartilages,  the molecules involved in regulating cartilage development in embryonic lamprey,  and measure the physical properties of the non-collagenous cartilages.

      This research is supported by NSERC.

       Graduate student positions are available.

Publications

1. Robson, P., G.M. Wright, E. Sitarz, A. Maiti, M. Rawat, J.H. Youson, F.W. Keeley. 1993. Characterization of lamprin, an unusual matrix protein from lamprey cartilage. J. Biol. Chem., 268:1440-1447.

2. McBurney, K.M., F.W. Keeley, F.S.B. Kibenge, G.M. Wright. 1996. Spatial and temporal distribution of lamprin mRNA during chondrogenesis of trabecular cartilage in the sea lamprey. Anat. Embryol., 193:419-426.

3. McBurney, K.M., G.M. Wright. 1996. Chondrogenesis of a non-collagen-based cartilage in the sea lamprey, Petromyzon marinus. Can. J. Zool., 74: 2118-2130.

4. Robson, P., G.M. Wright, J.H. Youson, F.W. Keeley. 1997. Non collagen-based cartilages in the skeleton of the sea lamprey, Petromyzon marinus. Comp. Biochem. Physiol., 118B: 71-78.

5. Wright, G.M., F.W. Keeley, P. Robson. 2001.   The unusual cartilaginous tissues of jawless craniates, cephalochordates and invertebrates.   Cell Tissue Res., 304:165-174.

6. Robson, P., G.M. Wright, F.W. Keeley.  2000.  Distinct non-collagen based cartilages comprising the endoskeleton of the Atlantic hagfish, Myxine glutinosa. Anat. Embryol., 202:281-290.

7. Robson, P., G.M. Wright, J.H. Youson, F.W. Keeley.  2000.  The structure and organization of lamprin genes:  Multiple-copy genes with alternative splicing and convergent evolution with insect structural proteins.  Mol. Biol. Evol., 17:1739-1752.

8. Morrison, S.L., C.K. Campbell, G.M. Wright.  2000.  Chondrogenesis of the branchial skeleton in  embryonic sea lamprey, Petromyzon marinus.  Anat. Rec., 260:252-267.

9. Richardson, M.K., G.M. Wright. 2003.  Developmental transformations in a normal series of embryos of the sea lamprey Petromyzon marinus (Linneaus).  J. Morphol., 257:348-363.

10. Courtland, H.W.,  G.M. Wright, R.G. Root, M.E. DeMont. 2003.  Comparative equilibrium mechanical properties of bovine and lamprey cartilaginous tissues.  J. Exp. Biol., 206:1397-1408.

For more information contact:
Dr. Glenda Wright
550 University Avenue
Charlottetown, P.E.Island
C1A 4P3

phone: (902)566-0805
fax: (902)566-0832

Last updated February 2005
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