Abstract
Five species belonging to order Chelonia, two families and four genera, namely, Taiwanese soft-shelled turtle, Pelodiscus sinensis japonicus; American soft-shelled turtle, Apalone ferox; alligator snapping turtle, Macroclemys temminck; pitted shelled turtle, Carettochelys insculpta and side-necked turtle, Chelodina siebernrocki were investigated in order to fully understand the structural basis for the multiple lactate dehydrogenase (LDH) isozymes in turtles and soft-shelled turtles. Starch gel electrophoretic patterns of LDH isozymes from muscle, heart, liver, testis and eye were analyzed. Chelonia possess the two fundamental LDH loci-A¡]muscle¡^and B¡]heart¡^as the case of all other vertebrates. The major forms of LDH isozymes in the tissues of Chelonia are homotetrameric LDH-A4 and B4.While some of these Chelonia do not form two heterotetrameric A3B1 and/or A1B3 isozymes. This phenomenon is also observed among some lower vertebrates and fishes of other classes.
I have determined the LDH-A and LDH-B cDNA sequences of protein-coding region from these five species. The 3D-structure of tetrameric LDH isozymes from Taiwanese soft-shelled turtle was predicted by homologous modeling and the substitutive residues in subunit contact sites were examined in oder to explain different multiple forms of tetrameric LDH isozymes present in various species.
The LDH isozymes are housekeeping genes in most eukaryotic cells and therefore the LDH DNA or protein sequences can be an ideal marker for studying the molecular phylogenetics and evolution among different organisms. However, whether this marker can also be used to investigate the systematic relationship among the closely related species remains to be demonstrated. In this study, the newly determined LDH-A and LDH-B cDNA sequences and their deduced protein sequences from several different turtles and soft-shelled turtles, as well as the previously published LDH sequences, are analyzed by phylogenetic tree reconstruction methods of neighbor-joining, minimum evolution, maximum parsimony and maximum likelihood. These results confirm the traditional classification based on morphology of Chelonia as the two different families belonging to the same order Chelonia. Furthermore, these results clearly classify these Chelonia species into side-necked turtle, rough-shelled hide-necked turtle and smooth-shelled hide-neck turtle. Finally, these results also demonstrate that LDH can indeed be used as a molecular systematic marker for analyzing closely related species.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0710101-133832 |
| Date | 10 July 2001 |
| Creators | zo, Ho-wan |
| Contributors | Lee-Sin Che, Shyh-Horng Chiou, Li-Shoei Lung |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0710101-133832 |
| Rights | unrestricted, Copyright information available at source archive |
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