• Fisheries and Aquatic Sciences
• /
• v.15 no.4
• /
• pp.317-324
• /
• 2012

We characterized the cytoskeletal beta-actin (${\beta}$-ACT) gene (actb) and its 5'-upstream regulatory region in the Javanese ricefish Oryzias javanicus. The gene and protein structures were deduced from amino acid sequences of the actb gene and conserved in the teleost lineage. The O. javanicus actb gene has common transcription factor binding motifs in its regulatory region found in teleostean orthologues. Following quantitative reverse transcription-PCR, actb gene transcripts were detected in all tissues examined; however, the basal expression levels were different. During early development, O. javanicus actb mRNA levels showed a gradual increase and peaked between late somitogenesis and the heartbeat stage. Microinjection of O. javanicus embryos with the actb gene promoter-driven red fluorescent protein (RFP) gene reporter vector showed a ubiquitous distribution of RFP signals, although most exhibited a mosaic pattern of transgene expression. A small number of microinjected embryos displayed a wide distribution of RFP signals over their entire body, which resembled the expression pattern of endogenous actb. Data from this study provide a basis to develop a transgenic system with ubiquitous expression of foreign genes in O. javanicus.

• Fisheries and Aquatic Sciences
• /
• v.15 no.4
• /
• pp.325-335
• /
• 2012

The present study characterized the fast skeletal myosin light chain-2 gene (mlc2f) in the euryhaline Javanese ricefish (Oryzias javanicus: Beloniformes). Coding nucleotide and deduced amino acid sequences of Javanese ricefish mlc2f were well conserved in the vertebrate lineage. Javanese ricefish mlc2f showed a typical seven-exon structure, and its promoter exhibited transcription factor binding motifs common to most muscle-specific genes. However, Javanese ricefish mlc2f also displayed tandem duplications of intronic sequences in both intron 1 and intron 3. Based on quantitative reverse transcription-polymerase chain reaction, the mlc2f transcripts were highly predominant in skeletal muscles of adults and were differentially modulated during embryonic development. Microinjection of the mlc2f promoter-driven red fluorescent protein (RFP) reporter construct successfully exhibited heterologous expression of the fluorescent reporter, primarily in muscular areas of hatchlings, although the distribution pattern of RFP signals was not uniform due to the mosaic nature of the introduced transgene. Data from this study indicate that the Javanese ricefish mlc2f gene has undergone "intra-intronic" duplication events in a species-specific manner and that the mlc2f regulator may also be useful in heterologous expression assays of the skeletal muscles of this species.

• Animal Systematics, Evolution and Diversity
• /
• v.13 no.1
• /
• pp.9-20
• /
• 1997

한국산 송사리 (Oryzias)속의 송사리 (O. latipes)와 대륙송사리(O. sinensis)의 집단 내 유전적 변이 및 종간 유연관계를 밝히고자 남한의 16개집단과 일본산 송사리(O. latipes) 1개 집단 등 총 17개 집단에 대한 isozyme 분석을 실시하였다. Isozyme 분석 결과 17개의 효소 및 비효소단백질에서 총 32개의 유전자를 검출한 결과, 전체 유전자중 Est-1과 Est-3 는 종 특유의 유전적 표식인자(genetic marker)였다. 송사리집단 중 진도집단의 유전적 변이 가 가장 낮았으며(Ho=0.011, He=0.043), 대륙송사리 서천집단의 유전적 변이가 가장 높았 다.(Ho=0.114, He=0.124). 한국산 송사리 11개 집단의 평균 유전적 변이 정도는 P=12.7%, Ho=0.029, He=0.042, 대륙송사리 5개 집단의 평균 유전적 변이정도는 P=26.3%, Ho=0.082, He=0.097로 각각 나타나 대륙송사리집단의 유전적 변이 정도가 송사리집단에 비해 약 2.5배 정도 높았고 일본산 송사리의 유전적 변이 정도는 P=15.6%, Ho=0.073, He=0.068로 나타났 다. 한국산 송사리와 일본산 송사리와의 유연관계는 S=0.761(D=0.243)로 나타나 유전적으로 뚜렷한 별개의 분류군으로 생각되며, 대륙송사리와 송사리간의 종간 유전적 근연치는 S=0.648(D=0.389)로 일반적인 척추동물의 종간 유전적 분화 수준을 나타냈다.

• Journal of Environmental Health Sciences
• /
• v.33 no.6
• /
• pp.513-516
• /
• 2007

This investigation was intended to find out the estrogenic effect of chlortetracycline (CTC) on vitellogenin induction in adult male Japanese medaka (Oryzias latipes). Vitellogenin (Vtg) produced in male fish has been used to as one of a biomarker of endocrine disrupters. The positive control was $17{\beta}-estradiol$ (E2) that induced Vtg in male fish. As a result, male and female fish were exposed to 0.1, 1, 10 and 100 ppm of CTC. Western blot results showed approximately 205 kDa, that is similar to myosin at high molecular weight range Sigma maker. Vtg band was showed fainted to 10 and 100ppm for chlortetracycline. Vtg concentration of CTC was qunatified by total protein quantification and ELISA. Exposure of the male fish to CTC of 0.1, 1, 10 and 100 ppm produced Vtg concentrations of 0.24, 0.12, 7.61 and 40.02%o, respectively, that value was elevated than control male fish (0.14%o). CTC exerted as a Vtg inducer in male fish from 10 ppm, but it was a reducer in female fish from 0.1 ppm level. The results say that vitellogenin induction patterns alter in male medaka treated with CTC, and that CTC may caused endocrine disruption in fish.

• Fisheries and Aquatic Sciences
• /
• v.18 no.1
• /
• pp.65-71
• /
• 2015

The functional utility of a transgenic marine medaka Oryzias dancena strain carrying the red fluorescent protein (RFP) gene driven by an endogenous choriogenin H (chgH) promoter was evaluated for its ability to detect waterborne $17{\alpha}$-ethinylestradiol (EE2), a synthetic estrogen derivative. The chgH:rfp transgenic marine medaka larvae showed an age-dependent tendency in the efficiency of EE2-mediated transgene expression, in which transgenic larvae older than 6 days post-hatching displayed a more effective response in their transgene expression to EE2 than did younger hatchlings. During experimental exposures to high concentrations of EE2 (200 to 1,000 ng/L), the transgenic responses in the hatchlings were broadly dose- and duration-dependent. With exposures using lower doses of EE2 (25, 50 and 100 ng/L), EE2-induced transgenic RFP was also observed in the transgenic larvae, although the lower doses required exposure of longer duration. Under the EE2 exposure and microscope assay conditions used in our study, transgenic marine medaka larvae exhibited a similar degree of EE2-mediated RFP phenotype expression at various salinity levels (0, 15 and 30 ppt).

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.50 no.2
• /
• pp.160-168
• /
• 2017

Optimizing the conditions for stem cell culture is an essential prerequisite for the efficient utilization of stem cells. In the culture of fish embryonic stem cells (ESCs) or ESC-like cells, embryo extracts are important for stable growth, but there is no rule for determining the developmental stage of the embryos used to obtain extracts. Therefore, this study investigated the effects of the developmental stage of extract donor embryos on the culture of Oryzias dancena ESC-like cells. O. dancena ESC-like cells were cultured in different media containing each of four types of embryo extract depending on the developmental stage of the extract donor embryos. Growth, morphology, colony-forming ability, alkaline phosphatase (AP) activity, and embryoid body (EB) formation of the cells were investigated. While the developmental stage of the extract donor embryos did not influence the growth, morphology, AP activity, or EB formation of ESC-like cells, colony-forming ability was affected and the pattern of the effects differed completely between the two ESC-like cells investigated. These results suggest that the developmental stage of extract donor embryos should be selected carefully for the culture of ESC-like cells, according to the research purpose and type of cell line.

• Fisheries and Aquatic Sciences
• /
• v.17 no.4
• /
• pp.479-486
• /
• 2014

To evaluate their potential utility as an ornamental organism, novel transgenic marine medaka Oryzias dancena strains with a highly vivid fluorescent phenotype were established through transgenesis of a cyan fluorescent protein gene (cfp) driven by the endogenous fast skeletal myosin light chain 2 gene (mlc2f) promoter. The transgenic marine medaka strains possessed multiple copies of transgene integrants and passed their fluorescent transgenes successfully to subsequent generations. Transgenic expression in skeletal muscles at both the mRNA and phenotypic levels was, overall, dependent upon transgene copy numbers. In the external phenotype, an authentic fluorescent color was dominant in the skeletal muscles of the transgenic fish and clearly visible to the unaided eye. The phenotypic fluorescent color presented differentially in response to different light-irradiation sources; the transgenics displayed a yellow-green color under normal daylight or white room light conditions, a strong green-glowing fluorescence under ultraviolet light, and a cyan-like fluorescence under blue light from a light-emitting diode.

• Korean Journal of Environmental Biology
• /
• v.38 no.1
• /
• pp.137-145
• /
• 2020

The sectioned-body morphometric characteristics of the diploid and triploid marine medaka, Oryzias dancena, of both sexes were examined to collect basic data on the significant differences between the diploid and triploid fish. Significant differences between the diploid and triploid fish in both sexes were observed in the body circumference anterior to the base of the pelvic fin, the body circumference anterior to the base of the anal fin, the body circumference anterior to the base of the dorsal fin, the area anterior to the base of the pelvic fin, the area anterior to the base of the anal fin, the area anterior to the base of the dorsal fin, the total height anterior to the base of the pelvic fin, the total height anterior to the base of the anal fin, the height anterior to the base of the pelvic fin, the height anterior to the base of the anal fin, the width anterior to the base of the anal fin, the belly thickness II anterior to the base of the anal fin, section shape 2-1, and section shape 4-1 (p<0.05). These measurements were greater in the triploid marine medaka of both sexes than those in the diploid marine medaka of both sexes, and they were also greater in the male diploid and triploid marine medaka than those in the corresponding female fish. Therefore, the sectioned-body morphometric dimensions were greater in the triploid males than those in the triploid females and the diploid fish in this study.

• Molecular & Cellular Toxicology
• /
• v.4 no.4
• /
• pp.293-299
• /
• 2008

To screen the differentially expressed genes in cadmuim-exposed marine medaka fish (Oryzias javanicus), a candidate marine test fish for ecological toxicity, the differential display polymerase chain reaction (DD-PCR) was carried out, since the genome-wide gene expression data are not available in this fish species yet. A total of 35 clones were isolated from cadmium-exposed fish and their nucleotide sequences were analyzed. The differentially expressed gene candidates were categorized to response to stimulus (3); ion binding (3); DNA binding (1); protein binding (6); carbohydrate binding (1); metabolic process (4); biological regulation (3); cellular process (2); protein synthesis (2); catalytic activity (2); sense of sight (1); immune (1); neurohormone (1); signaling activity (1); electron carrier activity (1) and others (3). For real-time quantitative RT-PCR, we selected catalase, glucose-6-phosphate dehydrogenase, heat shock protein 70, and metallothionein and confirmed that cadmium exposure enhanced induction of these four genes.

• Fisheries and Aquatic Sciences
• /
• v.16 no.3
• /
• pp.177-185
• /
• 2013

The development of species-specific fish cell lines has become a valuable tool for biological research. In recent years, marine medaka Oryzias dancena has been recognized as a good experimental model fish but there are no reports of establishment of cell lines from this fish. In this study, two cell lines from O. dancena blastula embryos were established from 41 total trials (4.9%). The two cell lines displayed typical in vitro morphology and have been cultured for >121 passages, which corresponds to 293 days. The doubling times of the cell lines were 29.84 and 28.59 h, respectively, and both possessed the potential to expand in a clonal manner, albeit with significant differences between the two cell lines. The absence of any of the four main medium supplements; i.e., fish serum, fetal bovine serum, basic fibroblast growth factor, and medaka embryo extract, significantly inhibited growth. The proportion of cells possessing normal chromosome number was 45% and 46.7% of the cell lines, respectively. Taken together, two cell lines that proliferate continuously were established from marine medaka and these cell lines may provide a basic tool for characterizing the unique features of this fish species.