Here we report the cloning and characterization of chicken visfatin (also called pre-B cell enhancing factor; PBEF, or nicotinamide phosphoribosyltransferase; Nampt) gene. Sequence analyses revealed that the coding region of visfatin is 1,482 bp in length and encodes a protein of 493 amino acids, which shares high amino acid sequence identity not only to visfatin of human (94%), rat (94%), carp (89%), and zebrafish (89%), but also to Nampt of sponge (58%) and cyanobacterium (48%). The reverse transcription PCR assay and Northern-blot analysis demonstrated that visfatin was widely expressed in all chicken tissues examined. Using a dual luciferase reporter system, we further demonstrated that the cloned 1,372-bp fragment upstream of the putative translation start site (ATG) displayed the maximal promoter activity in cultured CHO, DF-1, and HEK293 cells, whereas the removal of its 5'-region (1,075 bp) or 3'-region (297 bp) could only partially reduce its promoter activity, implying that visfatin gene transcription was likely controlled by multiple promoters near the translation start site. Taken together, results from present study will contribute to our better understanding of the expression and roles of visfatin gene in chickens.

Repetitive sequences constitute a significant component of most eukaryotic genomes, and the isolation and characterization of repetitive DNA sequences provide an insight into the organization and evolution of the genome of interest. We report the isolation and characterization of the major classes of repetitive sequences from the genome of Panax ginseng. The isolation of repetitive DNA from P. ginseng was achieved by the reannealing of chemically hydrolyzed (200 bp-1 kb fragments) and heat-denatured genomic DNA to low C(o)t value. The low C(o)t fraction was cloned, and fifty-five P. ginseng clones were identified that contained repetitive sequences. Sequence analysis revealed that the fraction includes repetitive telomeric sequences, species-specific satellite sequences, chloroplast DNA fragments and sequences that are homologous to retrotransposons. Two of the retrotransposon-like sequences are homologous to Ty1/ copia-type retroelements of Zea mays, and six cloned sequences are homologous to various regions of the del retrotransposon of Lilium henryi. The del retrotransposon-like sequences and several novel repetitive DNA sequences from P. ginseng were used to differentiate P. ginseng from P. quinquefolius, and should be useful for evolutionary studies of these disjunct species.

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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 Cot 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.

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