• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.1
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• pp.73-81
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• 2012

Object: The aim of this study is to suggest a list of priority chemicals for the Hazard & Risk Evaluation of Chemicals (HREC) controlled by the Industrial Safety and Health Act (ISHA). Method: Screening assessment was done for 642 chemicals whose exposure threshold limit values were set by the Ministry of Employment and Labor (MOEL). Hazard data were collected from Korea Occupational Safety & Health Agency (KOSHA) and/or other toxicity database. Exposure data were obtained from KOSHA internal database. The hazard and exposure scores of chemicals were listed by order of priority in accordance with GHS classification and exposure index data. Result: From the result of screening risk assessment for 642 chemicals, we extracted a list of 13 priority chemicals for HREC performed by the ISHA. A priority list of 27 chemicals which have carcinogen, mutagen and/or reproductive toxicity but not controlled by the ISHA was suggested for additional evaluation as "chemicals for special management".

• Development and Reproduction
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• v.25 no.3
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• pp.123-131
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• 2021

We report on the gonadal structure abnormality and intersexuality found from a survey regarding the reproductive potential of the rock bream, Oplegnathus fasciatus, along the southern coast of Korea. In total, 448 samples were collected for histological analysis (total length 27.5±6.8 cm; total weight 522.9±385.6 g). The sex ratio (F:M) was 1:0.46 (n=307:141), with 68.5% being females. The frequency of oocyte atresia and ovarian neoplasm in the females was 85.3% and 21.5%, respectively, and the frequency of testicular lobule and cyst deformation and testicular neoplasm in the males was 73.1% and 37.6%, respectively. The scale formation in the ovary and testis was approximately 2.0% for both sexes. The intersexuality was 42.2%, with the intersexuality among females being 49.5%, which was significantly higher than that of males (26.2%). Such findings indicate a negative impact on the reproductive output of the rock bream along the southern coast of Korea; however, a more detailed study is required to ascertain accurate causes.

• Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.256-267
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• 2023

The suitability of any fish species for successful aquaculture requires basic information on its reproduction and growth. This study investigated some facets of the reproductive biology of Synodontis shall (Mochokidae) from River Siluko in Nigeria. Fish samples were collected forth-nightly for a duration of fourteen (14) months-March 2015 to April, 2016 with the assistance of artisanal fishermen. Fishes were identified using taxonomic guides and standard techniques were used for determination of sex ratio, gonad maturation and fecundity. Linear regression method was used to define the correlation between fecundity and fish length, body weight and ovary weight. Results showed that sex ratio did not indicate a significant divergence (p > 0.05) from the 1 male to 1 female distribution ratio (1:1.41). Gonad morphology revealed paired gonads. Testes and ovaries were classified into four maturity stages: immature, resting, ripening and ripe. Gonadosomatic index ranged from 0.04 to 5.68 (males) and 0.03 to 20.19 (females). Absolute fecundity ranged from 1,014 to 4,520 eggs (mean = 2,592 eggs) and did not correlate significantly (p > 0.05) to ovary weight. This study has contributed to existing data on the biology of freshwater fish species in Nigeria and provided valuable information for fishery management tools in the conservation and utilization of this valuable freshwater fish species.

• Journal of Environmental Health Sciences
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• v.44 no.1
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• pp.76-89
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• 2018

Background: Exposure to endocrine disrupting chemicals (EDCs) has been considered one of the main causes of a range of endocrine diseases in modern society. An EDC priority list considering exposure, toxicity, and societal concern should be established for EDC management. Methods: The chemical ranking and scoring (CRS) system for EDCs was based on exposure, toxicity,and societal concern. The exposure score system was based on usage, circulation volume, bioaccumulation, and detection in consumer products. The toxicity score system was based on carcinogenicity and reproductive and developmental toxicity. The societal concern score system was based on domestic or international regulations and mass media reports. Results: A total of 165 EDCs were considered in the CRS system. The top-five priority EDCs were Bis(2-ethylhexyl) phthalate (DEHP), Benzene, Bisphenol A, Dibutyl phthalate (DBP) and Trichloroethylene. Phthalates, bisphenols and parabens were identified as priority chemical groups. Conclusion: We developed a CRS system for EDCs to identify priority EDCs for management. This will be a foundation to provide an EDC management plan based on scientific decision-making.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.489-497
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• 2021

Climate change is affecting the evolutionary trajectories of individual species and ecological communities, partly through the creation of new species groups. As population shift geographically and temporally as a result of climate change, reproductive interactions between previously isolated species are inevitable and it could potentially lead to invasion, speciation, or even extinction. Four species of abalone, genus Haliotis are present along the Korean coastline and these species are important for commercial and fisheries resources management. In this study, genetic markers for fisheries resources management were discovered based on genomic information, as part of the management of endemic species in response to climate change. Two thousand one hundred and sixty one single nucleotide polymorphisms (SNPs) were discovered using genotyping-by-sequencing (GBS) method. Forty-one SNPs were selected based on their features for species classification. Machine learning analysis using these SNPs makes it possible to differentiate four Haliotis species and hybrids. In conclusion, the proposed machine learning method has potentials for species classification of the genus Haliotis. Our results will provide valuable data for biodiversity conservation and management of abalone population in Korea.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.8
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• pp.1133-1139
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• 2015

This study aimed to determine the effects of parenteral selenium (Se) and vitamin E supplementation on economic impact, milk yield, and some reproductive parameters in high-yield dairy cows in the dry period and in those at the beginning of lactation. At the beginning of the dry period, cows (n = 323) were randomly divided into three groups as follows: Treatment 1 (T1), Treatment 2 (T2), and Control (C). Cows in group T1 received this preparation 21 days before calving and on calving day, and cows in group T2 received it only on calving day. The cows in the control group did not receive this preparation. Supplementation with Se increased Se serum levels of cows treated at calving day (p<0.05). Differences in milk yield at all weeks and the electrical conductivity values at the 8th and 12th weeks were significant (p<0.05). Supplementation with Se and Vitamin E decreased the incidence of metritis, the number of services per conception and the service period, but had no effects on the incidence of retained fetal membrane. A partial budgeting analysis indicated that Se supplementation was economically profitable; cows in group T1 averaged 240.6$ per cow, those in group T2 averaged 224.6$ per cow. Supplementation with Se and Vitamin E has been found to increase serum Se levels, milk yield, and has positive effects on udder health by decreasing milk conductivity values and incidence of sub-clinical mastitis.

• Journal of Veterinary Clinics
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• v.32 no.1
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• pp.78-84
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• 2015

Although researches have highlighted the important role of enhanced farm biosecurity to reduce the severity and prevalence of diseases in livestock, to date there has been little study in Korea on farmers' adoption of biosecurity measures to control porcine reproductive and respiratory syndrome virus (PRRSV) infection. To mitigate the risk of PRRSV infection in pigs, the risk factors by which PRRSV is introduced in pig farms must be determined. The primary aim of this study was to investigate pig producers' perceptions about on-farm biosecurity practices. We also analyzed data obtained from a cross-sectional study on 196 farrow-to-finish farms conducted between March 2013 and February 2014 to identify risk factors for PRRSV infection at farm level. Standardized questionnaires with information about basic demographical data and management practices were collected in each farm by on-site visit of trained veterinarians. Farms were classified as negative or positive through the use of infection profiles that combined data on PCR positive pigs and serological testing including antibody titer, sero-conversion pattern at each age category, and vaccination status. Data on biosecurity practices, farm management and environmental characteristics were analyzed using multivariate ordinal logistic regression. Generally, the biosecurity level in the pig farms included in this study were insufficient to reduce/prevent the risk of PRRSV infection given the high pig density areas and the considerable extent of vehicle movement. Factors associated with PRRSV infection were those where owners used on-farm vaccination programs had a lower risk of infection (OR = 0.19, 95% CI 0.06-0.61). The results from the analysis may guide to tailor biosecurity measures in the reduction or prevention of PRRS to the specific circumstances of pig farms in different localities of the world. To the best knowledge of the authors, this is the first study to report information on the biosecurity practices currently implemented on Korean pig farms.

• Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.140-149
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• 2010

We determined the seasonal gonad maturation in Strongylocentrotus nudus sea urchins inhabiting an artificially enhanced seaweed forest along the Samchuk Coast of Korea from April 2006 to March 2007. A total of 30 sea urchins per month were collected from the study area, and gonadosomatic index (GSI), gonad index (GI), egg diameter, and RNA/DNA variation were measured for each specimen. GSI values of female and male urchins achieved maximums of 17.6 and 17.0, respectively, in June. Based on histological studies, maximum GI values occurred in July (4.6 for females and 4.8 for males). A mean ovarian egg diameter of $73.7\;\pm\;14.2\;{\mu}m$ was measured in August; during the main spawning period in September, mean egg diameter reached a maximum of $74.2\;\pm\;17.8\;{\mu}m$. The RNA/DNA ratio and RNA content for both males and females showed a distinct peak during the ripe stage in July, but another peak occurred in the spring season from March to April, when urchins deposit protein into the nutritive phagocytes of immature gonads prior to gametogenesis. The reproductive cycle of S. nudus is divided into five stages: early active (December-May), late active (March-July), ripe (July-September), spent and degenerative (August-November), and inactive (October-February). Our continuous removal of sea urchins from the study area did not influence the reproductive cycle, as populations quickly recovered, and achieved normal gonad development cycle in the site.

• Reproductive and Developmental Biology
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• v.36 no.1
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• pp.79-85
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• 2012

Minipigs are regarded as one of the most important laboratory animal in that anatomical and physiological properties are similar to human and their reproduction efficiency is relatively higher compared to other large animal species. Particularly, several diseases that cannot be mimicked in rodent models are successfully occurred or induced in pig models therefore it has been interested in a valuable model for human diseases. Pigs are also 'standard' species in xenotransplantation research. To maximize experimental outcome using minipigs, establishment and management of proper animal facility, right animal husbandry and control of pathogens are very important. In this review, we summarized several international guidelines related with minipigs published by several companies or governments and discuss optimal conditions for providing informative ideas to the researchers who want to use minipigs in their future studies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.3
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• pp.253-261
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• 2012

We investigated the reproductive capacity of starry flounder Platichthys stellatus from the Uljin (UJ) marine ranching area and compared it to that of P. stellatus from the coastal waters of Pohang (PH). In UJ, female gonadosomatic index (GSI) peaked in October ($3.14{\pm}0.87$) and male GSI was high in October and December. In PH, female GSI peaked in January ($18.64{\pm}2.15$) while male GSI began to increase in October and remained high until March. Most ovaries of UJ females were immature with perinucleus oocytes, although the testes of UJ males were ripe in January. Both the ovaries and testes of PH starry flounders were ripe from January to March. The plasma estradiol-$17{\beta}$ ($E_2$) levels of UJ females were highest in October ($4.09{\pm}1.90$ ng/mL) although the testosterone (T) levels of UJ males were highest in December ($3.81{\pm}0.78$ ng/mL) and decreased gradually until April. The $17{\alpha}$,$20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$) levels of UJ females were not detected. The E2 levels of PH females were highest in December ($36.25{\pm}33.07$ ng/mL) and $17{\alpha}20{\beta}P$ levels were highest in March ($5.51{\pm}0.95$5 ng/mL). The T levels of PH males were highest in December ($4.03{\pm}1.34$ ng/mL) and decreased gradually until October. Taken together, these results suggest that most females from UJ did not reach maturation with a spawning period that was considered to be between December and January.