• Journal of Life Science
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• v.32 no.1
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• pp.29-35
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• 2022

This study was conducted to analyze the genetic polymorphisms of dopamine receptor D4 (DRD4) in horse breeds and its association with substrate characteristics in Jeju crossbreds (Jeju Horse × Thoroughbred). Polymorphisms in DRD4 are candidate genes associated with temperament in various mammals, including humans. Single nucleotide polymorphism (SNP) G292A in the exon 3 region of the horse DRD4 has a reported association with curiosity and vigilance in thoroughbreds. Sanger sequencing was used to identify polymorphisms of the mutations in DRD4 in three horse breeds. The SNP frequency in Jeju horses was significantly different from the frequency in other breeds. Character evaluation, conducted in the Jeju crossbreds and scored using a temperament test and contact test, revealed a high correlation between each test. Comparison of the polymorphism in the DRD4 of horses and the results of the character evaluation revealed lower scores for all temperaments in horses carrying allele A. Comparison of the SNP of G292A and blood dopamine levels in Jeju crossbreds showed 2.87 times higher levels for the GA type than for the GG type. This study identified an association between DRD4 polymorphism and various test methods for evaluating horse temperament and levels of neurotransmitters. Further research could validate the use of this gene as a genetic marker for character evaluation.

• The Korean Journal of Mycology
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• v.12 no.3
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• pp.105-110
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• 1984

Seven seed samples of corn obtained from Kangweon Provincial Office of Rural Development, Kerea were tested for seed-borne fungi, and found that all the samples tested were infected with Fusarium moniliforme to an extent of $6.0{\sim}79.5%$. Severely infected seed samples showed poor germination on blotter. Seed component plating showed that the fungus present not only in tip caps, pericarps and endosperms, but also in embryos. Heavy infection of the fungus caused severe seed rot and seedling blight in soil, but the damage was not severe and many plants grew without any symptoms when the seeds with light infection were sown in soil. However the fungus was frequently detected from inside of the stems of healthy looking seedlings. The results indicate that the fungus transmit from seed to plant systemically. In inoculation experiments, the fungus produced stem rots on corn plants of 110 days old. The cultivar of Hwangok 3 was revealed more susceptible to the fungus than that of Suweon 19.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.2
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• pp.71-96
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• 1977

Early development Linuparus trigonus(von Siebold) has been studied based on the samples collected monthly in Je-ju Island, Korea from February, 1975 to January, 1977. Gametogenesis, reproductive cycle, embryonic development were investigated by histological mettled, and morphological description was made on the first phyllosoma larva which reared in the laboratory. Testis is composed of two tubular duct which are symmetrical with H-shaped appearance. Outer layer of testis is of fibrous connective tissue capsule. In the lumen there is a convoluted seminiferous tubule with interstitial tissue. Ovary is a pair of symmetrical blind tubular lobes, and the midportions are connected each other. The ovary consists of a couple of ovarian sacs partitioned by two-layered connective tissue fibers. Proliferation of spermatogonia are observed all the year around on the germinal epithelium of seminiferous tubule. Partial spermatogenesis is always in progress, and the spermatozoa appear all the year around in the tubules. Nutrition of early oogonia is supplied by fibrous mesenchyme which is abundantly distributed in ovarian sacs. Oocytes grow and couplete maturation divisions in the follicle layers. They finally develop into mature ova before spawning. Reproductive cycle is classified into four successive stages; multiplication stage from September to December, growing stage from January to March, maturation division stage from April to May and mature stage from June to August. Spawning takes place from May to August with peak spawning from Into July to early August. Cleavage type is superficial. Blastopore is formed in blasto-disc region which is proliferation of blastoderm cells. Germinal layers are also derived from tile region. Mesoderm formation is originated from endodermal cells which are formed front the blasto-disc region. The endodermal cells are separated by the process of delamination from yolk sac and take part in the formation of the mid-gut. Morphological characteristics of first phyllosoma larva are different from the larvae of other Palinurid and Scyllarid species.