Byung-Hwa Min

Evaluation of developmental toxicity and teratogenicity of diclofenac using Xenopus embryos

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) with analgesic and anti-pyretic properties. This compound is therefore used to treat pain, inflammatory disorders, and dysmenorrhea. Due to its multimodal mechanism of action and ability to penetrate placenta, diclofenac is known to have undesirable side effects including teratogenicity. However, limited data exist on its teratogenicity, and a detailed investigation regarding harmful effects of this drug during embryogenesis is warranted. Here, we analyzed the developmental toxic effects of diclofenac using Xenopus embryos according to the Frog Embryo Teratogenesis Assay-Xenopus (FETAX) protocol. Diclofenac treatment exerted a teratogenic effect on Xenopus embryos with a teratogenic index (TI) value of 2.64 TI; if this value is higher than 1.2, the cut-off value indicative of toxicity. In particular, mortality of embryos treated with diclofenac increased in a concentration-dependent manner and a broad spectrum of malformations such as shortening and kinking of the axis, abdominal bulging, and prominent blister formation, was observed. The shape and length of internal organs also differed compared to the control group embryos and show developmental retardation on histological label. However, the expression of major tissue-specific markers did not change when analyzed by reverse transcription-polymerase chain reaction (RT-PCR). In conclusion, diclofenac treatment can promote teratogenicity that results in morphological anomalies, but not disrupt the developmental tissue arrangement during Xenopus embryogenesis.

Pick1 modulates ephrinB1-induced junctional disassembly through an association with ephrinB1

Members of the Eph family have been implicated in the formation of cell-cell boundaries, cell movement, and positioning during development in the context of cancer progression. De-regulation of this signaling system is linked to the promotion of more aggressive and metastatic tumor phenotypes in a large variety of human cancers, including breast, lung, and prostate cancer, melanoma, and leukemia. Thus, it is interesting to consider the case of cancer progression where de-regulation of the Eph/ephrin signaling system results in invasion and metastasis. Here, we present evidence that Pick1, one of the essential components of the adherens junction, recovers ephrinB1-induced cell-cell de-adhesion. Loss of Pick1 leads to dissociation of epithelial cells via disruption of the adherens junction, a phenotype similar to ephrinB1 overexpression. In addition, overexpressed ephrinB1-induced disruption of the adherens junction is rescued via binding to Pick1. These data indicate that Pick1 is involved in regulating the cell-cell junction in epithelial cells, and this may influence therapeutic strategy decisions with regards to cell adhesion molecules in metastatic disease.

Seasonal Variation in Subtidal Seaweed Community Structure at Hajung, on the Southeast Coast of Korea

Subtidal benthic macroalgal flora and community structure on barren grounds were examined seasonally along vertical shore gradients on the rocky shore of Hajung, Pohang, on the southeast coast of Korea, from February 2005 to November 2006. Twenty-six seaweed species were identified, including 5 green, 7 brown, and 14 red algae. The number of seaweed species ranged between 7 and 17 among seasons and between 13 and 20 species were found in vertical gradients along the shore. Over the study period, average seaweed biomass (g wet wt/) was 299.88 g and it ranged seasonally from 120.99 to 620.00 g. Seaweed biomass declined with increasing seawater depth and ranged between 323.06 and 593.68 g. The dominant seaweed species, in terms of biomass, were Desmarestia ligulata and Sargassum honeri, which grew at depths between 5 and 10 m. The red alga Delisea pulchra was also abundant at a depth of 15 m. No seasonal patterns were found in community indices. Along vertical shore gradients, community indices showed different patterns; the dominance index increased and the richness, evenness, and diversity indices decreased with seawater depth.

Semen cryopreservation of yellow croaker Larimichthys polyactis

The effects of various extenders and cryoprotectants on movable spermatozoa ratio (MSR), spermatozoa velocity (SV) and duration of spermatozoa motility (DSM) of post-thawed spermatozoa were examined. The MSR, SV and DSM of post-thawed sperm in artificial seminal plasma (ASP) extender were higher than those in marine fish Ringer’s solution (MFRS) extender (Pxa0<xa00.01) and was not significantly different from that of fresh sperm. No significant differences were observed in the motility parameters between fresh spermatozoa and frozen-thawed spermatozoa cryopreserved with ASP extender supplement 10% EG (ethylene glycol) cryoprotectant. Using the above method, yellow croaker semen was cryopreserved with extender ASP and 10% EG. As a result, at the spermatozoa/egg ratio of 100,000:1, the fertilization rate and hatching rate of the frozen-thawed spermatozoa cryopreserved for 1xa0week or 1xa0year in liquid nitrogen (45.7xa0±xa03.2% and 27.2xa0±xa05.0% or 37.5xa0±xa04.4% and 27.2xa0±xa05.0%) were similar to that of fresh spermatozoa (51.0xa0±xa03.1% and 36.7xa0±xa02.2%). There was a small alternation of shape in cryopreserved spermatozoa compared with fresh spermatozoa. In conclusion, the optimal conditions for yellow croaker semen cryopreservation are ASP extender supplement 10% EG cryoprotectant. This is the first report on semen cryopreservation of yellow croaker Larimichthys polyactis.

Perfluoroheptanoic acid affects amphibian embryogenesis by inducing the phosphorylation of ERK and JNK

Perfluoroalkyl compounds (PFCs) are globally distributed synthetic compounds that are known to adversely affect human health. Developmental toxicity assessment of PFCs is important to facilitate the evaluation of their environmental impact. In the present study, we assessed the developmental toxicity and teratogenicity of PFCs with different numbers of carbon atoms on Xenopus embryogenesis. An initial frog embryo teratogenicity assay-Xenopus (FETAX) assay was performed that identified perfluorohexanoic (PFHxA) and perfluoroheptanoic (PFHpA) acids as potential teratogens and developmental toxicants. The mechanism underlying this teratogenicity was also investigated by measuring the expression of tissue-specific biomarkers such as phosphotyrosine‑binding protein, xPTB (liver); NKX2.5 (heart); and Cyl18 (intestine). Whole‑mount in situ hybridization, reverse transcriptase‑polymerase chain reaction (RT-PCR), and histologic analyses detected severe defects in the liver and heart following exposure to PFHxA or PFHpA. In addition, immunoblotting revealed that PFHpA significantly increased the phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), while PFHxA slightly increased these, as compared with the control. These results suggest that PFHxA and PFHpA are developmental toxicants and teratogens, with PFHpA producing more severe effects on liver and heart development through the induction of ERK and JNK phosphorylation.

Oxygen Consumption of Long-term Cultured Male Black porgy Acanthopagrus schlegelii in Freshwater by Water Temperature During the Reproductive Period

Oxygen consumption (OC) of male black porgy Acanthopagrus schlegelii reared in freshwater (BFW) and seawater (BSW) during the reproductive period was 165.4±11.0, 77.6±8.0 mg O2/kg/h at 15 , °C 186.2±13.1, 133.4±6.7 mg O2/kg/h at 20 and 267.9±19.1, 198.6±8.3 mg O °C 2/kg/h at 25 , respectively. °C During the non-reproductive period, it was shown as 174.0±7.0, 85.6±5.5 mg O2/kg/h at 15 , 200.6±11.1, °C 119.2±8.7 mg O2/kg/h at 20 and 271.1±7.5, 194.7±16.7 mg O °C 2/kg/h at 25 , respectively. Thus, OC of °C BFW was higher than BSW both for non-reproductive and reproductive period. Also, OC increased in proportion to the rise in water temperature, and there was no difference of OC between BFW and BSW at each water temperature during the reproductive or non-reproductive period. OC of BFW and BSW showed clear circadian rhythms on photic conditions of reproductive and non-reproductive period, and the fish consumed more oxygen during the dark phase than for the light phase. In particular, OC of BFW during the reproductive period increased more sharply compared to non-reproductive period when the increase of water temperature was accompanied by the shift from dark to light phase. This implies that they react to the light more sensitively for reproductive period than for non-reproductive period.

Changes on Hematological Factors and Oxygen Consumption of Korean Rockfish Sebastes schlegeli in High Water Temperature

Aquaculture production of Korean rockfish Sebastes schlegeli has been continuously increased from 2000s and the fish has become the second most important mariculture fish in Korea. However, there are some environmental problems in aquaculture of Korean rockfish recently. In this regards, stress responses to high water temperature was examined via oxygen consumption, blood physiological parameter and endocrinological method. Oxygen consumption of Korean rockfish had significantly increased with rising water temperature. And oxygen consumption during the light time was no different with the dark time. The levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) showed no difference until 27°C, but it had rapidly increased at 30°C. Moreover high water temperature affected to increase in plasma glucose and cortisol levels. Key word : Korean rockfish, oxygen consumption, hematological fa 소제목: 고수온에 따른 조피볼락의 산소소비 및 혈액성상

Sex Ratio of Olive Flounder, Paralichthys olivaceus Populations Collected from Stocked Areas in Southwestern Sea of Korea

Olive flounder, Paralichthys olivaceus is one of the most target fish for aquaculture and national stock enhancement program in Korea. In order to find more information about hatchery fish stocking for stock enhancement we investigated the sex ratio of wild-caught fish populations which were artificially released into wild seas. The recapture rate was 9.0% to 94.5% in studied areas. The proportion of sex ratio ranged from 7.8% to 64.6% in female and from 34.4% to 92.1% in male respectively. This result suggests that the sex ratio of wild populations might be effected by the released fish. So we need more careful stocking program of the fish to preserve the balance of the sex ratio in the wild population.

Characterization of ticlopidine-induced developmental and teratogenic defects in Xenopus embryos and human endothelial cells

Ticlopidine is an anti-platelet drug that inhibits platelet aggregation via the functional alteration of platelet membranes. However, the mechanism underlying the adverse developmental effects of ticlopidine has not been clearly demonstrated. In this study, we evaluated the developmental toxicity and teratogenicity of ticlopidine on Xenopus laevis embryos and in human umbilical vein endothelial cells (HUVECs) using a frog embryo teratogenesis assay-Xenopus (FETAX) and blood and lymph vessel formation assays. Ticlopidine induced teratogenicity and inhibited growth, as evidenced by mortality rates and embryo lengths, respectively. Moreover, ticlopidine induced severe hemorrhages and inhibited both blood and lymph vessel formation by modulating the expression of xMsr and Prox1 in Xenopus embryos. Additionally, Nkx2.5 and Cyl104 levels were perturbed by ticlopidine exposure, and more extensive aberrations were observed in the liver and heart using whole-mount in situ hybridization. In addition, ticlopidine reduced branching in HUVECs by blocking the effect of the angiogenic vascular endothelial growth factor (VEGF). Results from this study suggest that ticlopidine is a developmental toxicant and teratogen and therefore this is a step forward in our understanding of the effects of ticlopidine during developmental processes.

Effects of Water Temperature and Salinity on Blood Properties and Oxygen Consumption in Hagfish (Eptatretus burgeri)

Abstract Hagfish Eptatretus burgeri is classified as a agnathans and has many different physiological properties compared with vertebrates. In this study, we examined effects of water temperature and salinity on blood properties and oxygen consumption in hagfish. In the experiment of water temperature change, hematocrit (Ht), red blood cell (RBC) and glucose of hagfish blood revealed the lowest values at 15℃. Oxygen consumption of hagfish had significantly increased with rising water temperature, and the increasing rate was twice as much when the temperature was manipulated every 5℃. Also, oxygen consumption during the night time (a short photoperiod) was significantly higher than that of the daytime. Q10 level was 3.50 in the light period and 3.92 in the dark period. No significant change in plasma glucose level was showned in changing salinity from 30 psu to 22 psu, while it had rapidly increased at 20 psu (13.7±4.0 mg/dL) and thereafter all hagfish were dead at 18 psu. However, osmolarity, Na+, K+ and Cl- levels had significantly decreased when salinity decreased. This results are expected to develop the artificial rearing techniques of natural hagfish.Key words : Hagfish, Water temperature, Salinity, Blood property, Oxygen consumptionCorresponding author : 051-629-5915, yjchang@pknu.ac.kr* (2013 ) .