Caligus sclerotinosus (Copepoda: Caligidae), a serious pest of cultured red seabream Pagrus major (Sparidae) in Korea

Caligid copepods (Crustacea) known as sea lice are pests of cultured fish, causing serious diseases and economic losses in fish aquaculture worldwide. One species, Caligus sclerotinosus Roubal, Armitage & Rohde, 1983 (Caligidae), is considered a serious pest of the highly prized red seabream Pagrus major (Temminck and Schlegel, 1843) (Sparidae) cultured in Japan. Recently, in neighboring Korea, red seabream culture has intensified and almost replaced yellow tail culture. However, until now, there have been no reports on infection of this sea louse from red seabream in Korea. We surveyed 120 (20 fish per month) P. major from a sea ranched Tongyeong Marine Research Center aquaculture facility, Gyeongsangnamdo, Korea for six months in 2011 (June to November). We recorded severe infection by the sea louse C. sclerotinosus on the skin of P. major. Prevalence was 100%, mean intensity 7.06, maximum intensity 49, and minimum intensity 2. Adult females (624), males (219) and few chalimi (5) were observed and identified by their morphology. As an average of all our collections, less than 0.6% of individuals were chalimi. We suggest, therefore, that adults of C. sclerotinosus undergo ontogenetic host switching after their final moult. No infection of C. sclerotinosus was found on wild P. major collected from Tongyeong and Yeosu fish markets on the southern coast of Korea. Severe infection by this sea louse may cause secondary infections of the host. This copepod is already reported from Australia and Japan and hence, this is the first report from Korea. We expect this pest to have an impact on Korean red seabream fisheries equally serious to that being experienced in Japan.     

Cloning and nucleotide sequence of the equine and elk pituitary pre-prolactin cDNA

We report the equine (Equs equs) and elk (Cervus elaphus) pituitary pre-prolactin (PRL) cDNA cloning, and their nucleotide and deduced amino acid sequences. Pre-PRL cDNA was obtained by RNA ligation mediated-rapid amplification of cDNA ends (RLM-RACE) and polymerase chain reaction (PCR). The elk pre-PRL cDNA exhibits two polymorphisms at positions 96 and 672, which are silent since they encode for the same amino acids, proline and isoleucine, respectively. We found no polymorphisms in the equine pre-PRL cDNA. The deduced amino acid sequence of the equine pre-PRL is 99% identical to the previously reported protein sequence. Pre-PRL mRNA is <1 kb in length and is highly expressed in the anterior pituitary gland, as demonstrated by Northern hybridization analysis. In summary, we cloned and sequenced the equine and elk pre-PRL cDNAs. The deduced amino acid sequence of elk and equine pre-PRL appears to be moderately conserved among other mammalian species. The polymorphic sites found in the elk cDNA could potentially be used in parentage testing and gene mapping.     

The porcine erythropoietin gene: cDNA sequence, genomic sequence and expression analyses in piglets

The porcine erythropoietin (EPO) gene and its cDNA have been cloned and characterized. The cDNA encodes a protein of 194 amino acids. The gene structure and sequence show a high degree of homology to the corresponding human and murine gene. Steroid hormone receptor binding sites are present both in the promoter and in the 3' flanking region of the gene, which also contains an oxygen-sensing sequence. The promoter lacks classical promoter elements such as TATA and CAAT boxes. Expression analyses using a competitive RT-PCR assay showed that the kidneys contain about ten times more erythropoietin mRNA than the liver in five-week-old piglets, thus indicating that the shift from mainly hepatic to mainly renal EPO production has taken place at this age. The testes showed a higher ratio of EPO mRNA to total RNA than the liver. Spleen showed very low levels of expression, while no expression of erythropoietin mRNA was detected in brain tissue, bone marrow, lung, lymph nodes, and ovaries.