Evolutionary Aspects of Gene Expression in the Pacific Angel Shark, Squatina california (Squatiniformes: Squatinidae)

Abstract

Horizontal starch gel electrophoresis was employed to examine gene expression in the Pacific angel shark, Squatina californica. Forty enzyme systems encoded by 72 presumptive gene loci were examined using 15 buffer systems and were scored for tissue expression in each of 12 tissues. To clarify aspects of enzyme evolution, the patterns of expression are described and compared to what is known for other vertebrates. The patterns of tissue-specific expression in S. californica were similar to those of other vertebrates, but some exceptions were noted. New findings described herein regarding the evolution of enzyme systems in the vertebrates include (1) additional support for the presence of a third creatine kinase locus, possibly Ck-B, in sharks; (2) the discovery of a new fructose-bisphosphatase locus, designated Fbp-C; and (3) the presence of only one supernatant NAD-dependent malate dehydrogenase (sMdh-A) compared to two sMDHs reported in bony fishes. This study has provided the baseline description of elasmobranch gene expression for future comparative studies of other species of sharks and rays.