DNA fingerprinting and cloning of hypervariable minisatellite repeats in salmonids

Abstract

We used heterologous jeffreys' 33.6 core sequence and microsatellites (CAC)(5) and (CA)(12) as probes and compared them with probes based on the minisatellite sequences from tilapia (Oreochromis niloticus) and Atlantic salmon (Salmo salar) in fingerprinting assays. DNA fingerprints generated with the Jeffreys' 33.6 core sequence and the microsatellite (CAC)(5) and (CA)(12) probes showed complex profiles with high background, but DNA fingerprints using the tilapia and Atlantic salmon probes showed clear, less complex, informative, individual-specific DNA fingerprints suitable for analysis. We cloned and sequenced homologous repetitive sequences using a novel approach of creating a chinook salmon (Oncorhynchus tshawytscha) genomic DNA library with enriched low C(0)t DNA repeats for the development of DNA probes. The four types of repeats identified and sequenced were (CT)(n) and three Alu-like sequences. We generated DNA fingerprints using one of the minisatellite sequences as a probe. This minisatellite sequence was shown to be species specific because it is abundant in chinook and coho salmon (Oncorhynchus kisutch) genomes, but not in Atlantic salmon. These probes will provide us with the tools to study pedigree and linkage analysis, paternity testing, breeding programs, and the analysis of genetic structure within populations for aquaculture and fisheries research.