Background: Cadmium (Cd) is toxic heavy metal that accumulates in organisms after passing through their respiratory and digestive tracts. Although several studies have reported the toxic effects of Cd exposure on human health, its role in embryonic development during preimplantation stage remains unclear. We investigated the effects of Cd on porcine embryonic development and elucidated the mechanism. Methods: We cultured parthenogenetic embryos in media treated with 0, 20, 40, or 60 μM Cd for 6 days and evaluated the rates of cleavage and blastocyst formation. To investigate the mechanism of Cd toxicity, we examined intracellular reactive oxygen species (ROS) and glutathione (GSH) levels. Moreover, we examined mitochondrial content, membrane potential, and ROS. Results: Cleavage and blastocyst formation rates began to decrease significantly in the 40 μM Cd group compared with the control. During post-blastulation, development was significantly delayed in the Cd group. Cd exposure significantly decreased cell number and increased apoptosis rate compared with the control. Embryos exposed to Cd had significantly higher ROS and lower GSH levels, as well as lower expression of antioxidant enzymes, compared with the control. Moreover, embryos exposed to Cd exhibited a significant decrease in mitochondrial content, mitochondrial membrane potential, and expression of mitochondrial genes and an increase in mitochondrial ROS compared to the control. Conclusions: We demonstrated that Cd exposure impairs porcine embryonic development by inducing oxidative stress and mitochondrial dysfunction. Our findings provide insights into the toxicity of Cd exposure on mammalian embryonic development and highlight the importance of preventing Cd pollution.

Cadmium (Cd), a heavy metal found in the aquatic environment, accumulates in organisms through the food chain. In the study, we investigated the survival rates, measurement of body Cd levels, and expression analysis of the stress response genes (Heat shock protein 70: HSP70 and Heat shock protein 60: HSP60) and antioxidant enzyme Glutathione S-Transferases (GST) on benthic oligochaete worm Tubifex tubifex exposed three concentrations of Cd, to analyze the bioaccumulation and changes of stress gene expressions to exposure toxicity of the Cd-spiked sediment. Survival rates of T. tubifex exposed to the Cdspiked sediment were 93% at 0.4 mg kg-1 Cd, 96% at 1.87 mg kg-1 Cd, and 93% at 6.09 mg kg-1 Cd for 10 days. Cd concentration in the body of T. tubifex was higher than that in the sediment. After Cd exposures for 10 days, the body Cd levels were 18.4 mg kg-1, 13.06 mg kg-1, and 79.11 mg kg-1 at exposed three concentrations of Cd, respectively. Upregulation of HSP70 gene expression was observed at all concentrations of exposed Cd as a time-dependent manner, whereas transcriptional expression of the HSP60 gene increased as a timedependent manner in T. tubifex exposed to the relative high concentration (6.09 mg kg-1) of Cd. However, GST gene expression increased on day 1 at all concentrations after Cd exposures, and then downregulated until 10 days. These results indicate to ecotoxicological and molecular effects in benthic oligochaete worm T. tubifex to Cd-spiked sediment and provide the basic information for the utilization of environmental toxicity assessment using the T. tubifex as a aquatic pollution indicator species.

국내외적으로 유해물질의 통합 노출에 대한 관심은 높아지고 있다. 이러한 흐름에 따라 다양한 경로를 통해 노출될 수 있는 중금속에 대한 통합 노출 연구가 필요하다. 카드뮴과 납은 각각 신장 독성과 인지 장애 등 다양한 독성을 나타낼 수 있으며 또한 발암 물질로 알려져있다. 따라서 본 연구에서는 카드뮴과 납의 노출량 추정 및 통합 위해성 평가를 진행하였다. 2016, 2017년의 7기 국민건강 영양조사에 참여한 10,733명의 식품, 물, 흡연과 간접흡연, 호흡, 화장품, 여성용 위생용품을 통한 중금속 노출 추정량을 계산하였다. 결과적으로 카드뮴과 납 모두 식품을 통한 노출이 제일 높게 나타났다. 이외에도 흡연은 카드뮴의 주요한 노출원이었으며, 납은 화장품을 통해 높은 농도로 노출되었다. 통합 위해평가에서도 식품이 가장 큰 영향을 미쳤다. 지역적 특성의 차이는 노출 추정량의 차이를 보이지 못하였으나, 연령 별, 성별 간 노출 추정량은 큰 차이를 보였다. 특히, 월경 중인 성인 여성의 경우 카드뮴, 월경 중이지 않은 여성은 납의 노출 추정량이 더 높으며 신체 대사를 고려하였을 때, 그 위험성이 더 클 수 있음을 암시하였다. 결론적으로 노출량 추정 및 통합 위해평가 모두 식품이 주요 노출원이었다. 다만, 잠재적 위험을 방지하기 위해 다른 경로에 대한 노출량 추정 및 위해평가가 요구된다.

In recent, the ISO has suggested a new guideline by using an avoidance behavior of soil invertebrates for the use of screening tools in the evaluation of soil contamination. In this study, we used a collembolan, Paronychiurus kimi which is native to Korea, as a test species because of its ecological relevance to Korean soil. The objectives of this study were to evaluate whether the exposure time (24, 48, 72, 96 and 120 h) and cadmium concentration (50, 100, 200 and 400 mg/kg of dry soil) affect the avoidance behavior of P. kimi. Twenty collembolans were introduced to the center of the soil which divided into two sections; cadmium untreated soil was placed in one of the section, and the cadmium treated soil was placed in the opposite section. To minimize soil structural effect on the avoidance behavior, the both soils were compacted by applying unidirectional force to the soil surface. The avoidance behaviors of P. kimi were not significantly affected by cadmium concentrations after 24 and 48 h of exposure, but were significant after 72-120 h. There results showed that avoidance behavior appears to be a good endpoint for the use in evaluation of soil contamination with 72 h of exposure duration.

We investigated the effects of cadmium exposure and various stress on the transcription of heat shock protein 70 and 82 (HSP70 and HSP82) from Pardosa astrigera wolf spider. To do this, P. astrigera HSP70 and HSP82 genes were cloned and its full-length sequence determined. Female spiders were long-term exposed to cadmium or to polychlorinated biphenyl (PCB) for 2, 4 and 6 weeks and short-term exposed to endosulfan by dietary uptake. Female spiders were also exposed to various temperatures. HSP82 did not show a clear tendency of transcription induction following exposure to cadmium. On the contrary, HSP70 transcription gradually increased during the exposure to 2, 20 and 40 mM of cadmium for 2, 4 and 6 weeks. Transcript level of HSP70 was not significantly changed by endosulfan and PCB exposure. In the short-term (3 hr) temperature exposure, an increased expression of HSP70 was observed under the heat shock to 30°C and then slightly decreased at 35°C. However, induction of HSP70 transcription was not observed during the long-term (7 days) temperature exposure. Taken together, HSP70 gene appears to be up-regulated by cadmium in a time-dependent manner but little affected by other potential contaminants. Analysis of HSP70 transcript levels in P. astrigera collected from various fields revealed that levels of cadmium concentration were well correlated with HSP70 transcript levels (r2 = 0.76). Taken together, it was suggested that transcript level of HSP70 could be useful as a biomarker for the long-term cadmium exposure of P. astrigera.

As a fundamental study for chronic test (definitive test), the range finding test must have been done prior to conducting chronic test. The aims of this study were 1) to search the effective concentration range of two different heavy metals (cadmium and nickel) to indigenous collembolan species (Paranura rosea) 2) to compare the toxicity of cadmium and nickel depending on exposure durations. Toxicity tests were conducted in accordance with the standardized toxicity test proposed by OECD. In this study, there were no mortality occurred at all test concentrations for 7-days exposure. In contrast to 7-days exposure, there were slight increases in mortalities were observed at the concentration higher than 400 mg/kg for both heavy metals for 14-days exposure. The estimated LC50s for cadmium and nickel were 3980.65 (2036.08-64668.61) and 1597.85 (1087.87-3817.61) mg/kg, respectively. The results of this study may be used as a fundamental toxicity data for two heavy metals to proceed in chronic test in the future study.