Jong-Man Yoon

Cyclooxygenase-derived products, rather than nitric oxide, are endothelium-derived relaxing factor(s) in the ventral aorta of carp (Cyprinus carpio)

In some fish blood vessels, the existence of a NO (nitric oxide) system has been reported. We examined the possibility that this NO system acts as an endothelium-derived relaxing factor (EDRF) in carp aorta using the carp aorta alone and in a combined carp-rat aorta donor-detector system. Use of the typical NO stimulating agent in mammal acetylcholine (ACh) only induced constriction of the carp aorta. This response was not modified by denudation or by NO synthesis inhibition with N-nitro-L-arginine methyl ester. Neither the indirect NO stimulating agents bradykinin and histamine nor the direct NO releasers sodium nitroprusside (SNP) and SIN-1 induced vasorelaxation. Both SNP and ACh elevated the cGMP concentration in rat aorta, but not in carp aorta. In the aorta combination set-up, where carp served as a NO donor and rat aorta served as a NO detector, no relaxation of the rat aorta was observed. The calcium ionophore A23187, a known EDRF producer in mammals, induced relaxation of carp aorta through an endothelium- and cyclooxygenase-dependent mechanism. These results indicate that carp aorta does not produce NO as an EDRF nor does it respond to exogenously supplied NO. The major EDRF in carp is apparently a product(s) of cyclooxygenase metabolism.

Genetic Distances and Variations of Three Clupeid Species Determined by PCR Technique

In this study, seven oligonucleotides primers were shown to generate the shared loci, specific loci, unique shared loci to each species and shared loci by the three species which could be obviously calculated. Euclidean genetic distances within- and between-species were also calculated by complete linkage method with the sustenance of the hierarchical dendevrepogram program Systat version 13. The genomic DNA isolated from herring (Clupea pallasii), Korean anchovy (Coilia nasus) and large-eyed herring (Harengula zunashi), respectively, in the Yellow Sea, were amplified several times by PCR reaction. The hierarchical dendevrepogram shows three chief branches: cluster 1 (PALLASII 01, 02, 03, 04, 06 and 07), cluster 2 (NASUS 08, 09, 10, 11, 12, 13 and 14), and cluster 3 (ZUNASHI 15, 16, 17, 18, 19, 20, 21 and PALLASII 05). In three clupeid species, the shortest genetic distance displaying significant molecular difference was between individual PALLASII no. 03 and PALLASII no. 02 (0.018). Individual no. 06 of PALLASII was most distantly related to NASUS no. 11 (genetic distance = 0.318). Individuals from herring (C. pallasii) species (0.920) exhibited higher bandsharing values than did individuals from Korean anchovy (C. nasus) species (0.872) (P<0.05). As a result, this PCR analysis generated on the genetic data displayed that the herring (C. pallasii) species was widely separated from Korean anchovy (C. nasus) species. Reversely, individuals of Korean anchovy (C. nasus) species were a little closely related to those of large-eyed herring (H. zunashi) species.

Effect of Levamisole on Enhancing Natural Cytotoxic Cell Activity in Nile Tilapia Oreochromis niloticus

The study examined the effect of levamisole on the natural cytotoxic cell (NCC) activity of Nile tilapia (Oreochromis niloticus) head kidney (HK) leukocytes. In vitro, HK leukocytes were incubated with to ng of levamisole/ml for 5, 20 or 40 h and then their NCC activity against target cells was assayed. The NCC activity appeared to increase after a 20 h of incubation. In vivo, tilapia were fed commercial diet containing 0, 50, 100 or 300 mg of levamisole/kg for 12 consecutive days. Then, the fish were fed a commercial normal diet and samples harvested weekly 0 to 8 weeks after levamisole administration. The NCC activity was augmented uniformly at all times examined until the end of the experiment. In conclusion, levamisole effectively enhanced and maintained tilapia NCC activity.