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Different types of transcripts encoding growth hormone (GH) were identified from cDNA libraries constructed with pituitaries of a marine fish species, greenling (Hexagrammos otakii). GH-homologous cDNA clones were isolated using the high-density filter hybridization and the expressed sequence tag techniques. Of 39 full-length positive cDNA clones, 31 clones () displayed an identical sequence, however, remaining 8 clones exhibited several polymorphisms in their sequences including (1) the length and sequence variability in the 5` upstream region, (2) insertional sequences in open reading frame, and (3) deletion and/or single nucleotide polymorphism in the untranslated 3` region. Based on RT-PCT and RNA dot blot analyses, these transcripts were proven to be expressed in a pituitary-specific manner.

Natural clonal stock of triploid crucian carp, Carassius aurahs was identified and its cytogenetic, molecular genetic and morphological traits were studied. Cytogenetic analysis of the clonal crucian carp revealed that they were natural triploidy, evidenced by 1.5-fold increases of cell size, DNA content, and chromosome number. Multi-locus DNA fingerprinting using probe showed that they had an identical fingerprint profile, indicating the clonal propagation of the population. External morphology and morphometric characteristics of triploid individuals were much uniform compared to those of diploids. Natural triploid crucian carp was proven to be all-female in this study.

Cytogenetic analysis was conducted to obtaining informations for genetic improvement of spotty belly greenling (Hexagrmmos agrammus) and greenling (H. otakii) in aquaculture. Erythrocytes of spotty belly greenling were slightly larger than those of greenling (p 0.92 while that of greening averaged 14.61 0.15 m^3 the difference was not significant (p>0.05). Consequently, genome size of spotty belly greenling was also slightly larger than those of greenling. DNA content per cell of spotty belly greenling and greenling were 2.15 pg and 2.10 pg, respectively. The modal chromosome number of both greenling species were same as 2n