미세플라스틱 입자는 환경 내 어디에나 존재하며 크기, 모양 또는 유형의 표준화된 입자가 아 니다. 따라서 독성자료를 바탕으로 해수, 퇴적물 등 해양환경의 다차원을 정확하게 평가하고 관리하는 위험평가 프레임워크를 구축하는 것은 매우 어렵다. 본 연구에서는 해양환경 미세플 라스틱의 특징과 영향을 조사하였고, 해양환경 미세플라스틱의 분포와 생물영향에 따른 위해 도 평가 프레임워크(초안)를 제안하고 있다. 환경 미세플라스틱의 특성은 매우 다양하지만 대 부분의 독성 데이터는 독특한 형태와 유형에 집중되어 있으며, 실험실 노출 생물과 관리해야 하는 생물 종도 다르다. 실제적으로, 지금까지의 수집된 연구결과는 위해성평가에 활용하기에 독성 데이터 품질에 있어 불확실성이 높기도 하며, 전통적인 위해성평가 프레임워크를 적용 하는 데 있어 고려할 부분이 많이 존재한다. 그러나, 현재 미세플라스틱 관리에 대한 국제사회 의 움직임이 점차 강화되고 있고, 해양환경의 미세플라스틱 오염도가 높아지고 있는 점을 고 려하면, 해양환경의 미세 플라스틱 특성에 기초한 위해성평가 기법 구축에 대한 추가 연구가 제안되어야 할 것이다.

Larvae from the marine medaka fish Oryzias javanicus were exposed with polystyrene microplastics (MPs) for 24 h. Exposure to waterborne fluorescent MPs showed clear ingestion and egestion in feces. Under constant MPs, the concentration of dissolved oxygen significantly decreased in 24 h compared to the control. Significant intracellular reactive oxygen species and malondialdehyde contents were detected in larvae, indicating oxidative stress and lipid peroxidation. Significant elevations in mRNA expressions of heat shock protein 70 and antioxidant defense system genes (glutathione reductase, glutathione peroxidase, catalase, and superoxide dismutase) were measured with increases in enzymatic activity of oxidative stress-related proteins. Taken together, the alterations to the molecular and biochemical components suggested that waterborne MPs had an oxidative stress effect on marine medaka larvae.

The inflammatory response to infections, such as bacteria and viruses is mediated by multiple host factors. The tumor related-genes are the important cytokines in mammals. However, a number of tumor related-genes are not identified in the rock bream. Here, we have reported the identification and molecular characterization of the tumor related genes. The LPS-induced TNF-α factor 1 and 2 (LITAF1, LITAF2), tumor necrosis factor superfamily member 14 (TNFSF14), tumor necrosis factor receptor superfamily member 14 (TNFRSF14) and translationally controlled tumor protein (TCTP), programmed cell death 10 (PCD10) from rock bream are used for the under investigations. The LITAF1 and LITAF2 consist of 138 and 163 amino acids with a conserved LITAF domain. TNFSF14 and TNFRSF14 comprise 266 and 181 amino acid, respectively. TCTP encompasses of 170 amino acid containing two conserved TCTP signatures. Furthermore PCD10 consists of 210 amino acids. Using quantitative real-time PCR, we have obtained expression analysis results of LITAF1 and 2, TNFSF14, TNFRSF14, TCTP, PCD10 in the various tissue. Compared to the control, the tumor related genes mRNA is detected at a high levels in gill (LITAF1, TCTP), intestine (LITAF2), liver (PCD10), spleen (TNFSF14) and RBC (TNFRSF14). We have also performed gene expression analysis in the kidney, spleen, liver and gill after challenging with Streptococcus iniae, Edwardsiella tarda and Red seabream iridovirus. We have acquired the dynamic regulated mRNA expression to each of pathogen according to the tissue. Expression of tumor related-genes mRNA are significantly increased by infected with pathogens in most of the tissue. But oddly, PCD10 mRNA is expressed significantly decreased by S. iniae infection in all of tissues. Our results reveal that rock bream tumor relatived-genes may be involved in rock bream immune responses to pathogen infections, as well as, they also act like potential biomarkers for innate immunity.

Translationally controlled tumor protein (TCTP) is one of important immune regulator. TCTP has been implicated in cellular processes including the cell growth, cell cycle progression, apoptosis regulation and the protection of cells against various stress condition. In this study, we cloned and characterized TCTP from rock bream (Oplegnathus fasciatus), which is an economically important species in the Korea aquaculture industry. The Full-length of rock bream TCTP (RbTCTP) cDNA was 1041 bp and contained an open reading frame (ORF) of 513 bp, which encoded 170 amino acid sequence. The 5' untranslated region (UTR) was 90 bp while the 3' UTR was 538 bp, containing a polyadenylation signal (ATTAAA). The identity of amino acid sequence was 76%, 75% and 74% in tilapia, orange-spotted grouper and Japanese seaperch, respectively. The positions of microtuble-binding region, Ca⁺ binding region and TCTP signature regions in RbTCTP were similar with those of other fish species and mammalian. The RbTCTP mRNA was expressed highest in the muscle. Expression of TCTP mRNA were significantly variable according to injection of red seabream iridovirus (RSIV), Streptococcosis (S. iniae) and Edwardsiella tarda (E. tarda).

Spilled oil into marine environments are known to induce disturbance not only hepatodetoxification system but also immune function in fish. However, toxic mechanisms on immune system and complex toxicity of crude oil have not been fully investigated. Innate immune response considered on the attractive effect-based monitoring tools due to their capacities to predict population disturbances by modification of disease susceptibility. In the study, to clarify the toxic effects of Hebei sprit spilled crude oil on fish immune system, multiple hepatodetoxific enzymes (Cytochrome P4501A and GST) and cytokines such as Interleukin-1beta (IL-1β), granulocyte colony-stimulating factor (G-CSF) were evaluated in juvenile Rockfish fed individually the gelatin-capsulated Iranian Heavy Crude Oil (IHCO). At 12 h after treatment, the oil-fed groups were shown higher concentrations of biliary 1-OH pyrene fluorescence metabolite and CYP1A expression than the control group. Cat. L and G-CSF mRNA also increased significantly at initial stage of exposure (from 12 h to 48 h after exposure) but decreased to the level of control group or less. 72 h post-oil injection, fish were intraperitoneallyadministered an LD50 dose of Streptococcus iniae (FP.5228; Korea Fish Diseases Information Center). Host survival was monitored for 7 days and cumulative mortality rate was calculated. Host mortality rate was increased significantly in oil exposure group compared to sham group.