• Environmental Analysis Health and Toxicology
• /
• 제21권1호
• /
• pp.81-86
• /
• 2006

Embryotoxicity tests were performed in Daphnia magna to assess aquatic ecotoxicity of bisphenol A, a well known industrial compound showing estrogen-like activity in vivo, and to examine their effectiveness in the toxicological assessment. The whole embryonic developmental period was classified into 6 stages and developmental abnormality was checked to evaluate the embryotoxicity. In the present study, bisphenol A showed the ability to interfere with embryonic development, suggesting its antiecdysteroidal activity. The rates of mortality, delayed development, deformity and immobility all showed good concentration-response relationship, demonstrating their possibility as useful toxicological indices in daphnid embryotoxicity tests that have been rarely performed so far. It seemed favorable to the test sensitivity that embryos are removed from maternal daphnids around 7 hr after deposition from the ovaries to the brood chamber. These results suggest that daphnid embryotoxicity tests can be one of useful tools available for the assessment of ecotoxicity of various chemicals in the aquatic environment.

• 컴퓨터교육학회논문지
• /
• 제13권1호
• /
• pp.27-36
• /
• 2010

지식정보사회를 살아가는 사람들에게 가장 중요한 능력인 문제해결력, 창의성 등의 고등사고력을 신장시키기 위해 알고리즘과 프로그래밍 교육을 중학교 정보 교육과정에 도입한 것은 적절하다. 그러나 형식적 조작기에 도달하지 못한 구체적 조작기 학생들에게 고등교육의 알고리즘과 프로그래밍 교육내용을 축소하여 제공하는 것은 학생들의 인지부담만 가중되며, 알고리즘 학습에서 배운 원리와 전략이 문제해결을 위한 프로그래밍으로 학습 전이가 어렵다. 본 연구는 인지 발달 단계 중에서 구체적 조작기에 해당하는 학생들의 발달 특성을 고려하고, 알고리즘 학습이 프로그래밍으로 전이할 수 있도록 선 알고리즘 후 프로그래밍 학습 모형을 개발하였고, 구체적 조작기 학생들을 대상으로 하여 학습 동기와 학업성취도에 미치는 영향을 검증하였다. 그 결과 선 알고리즘 후 프로그래밍 모형으로 학습한 구체적 조작기 학생들의 학습동기와 학업성취도 향상에 유의미한 차이가 있었다.

• 한국발생생물학회지:발생과생식
• /
• 제19권1호
• /
• pp.33-41
• /
• 2015

The gonadosomatic index (GSI), gonadal development and changes in hormones in plasma level of the indoor cultured grunt (Hapalogenys nitens) were investigated by histological study from August 2011 to October 2012. The GSI showed similar trends with gonad developmental stages during the culture periods. Changes in plasma level of estradiol-$17{\beta}$ of female H. nitens reached the highest value before the spawning period, and seasonal changes in plasma level of estradiol-$17{\beta}$ were similar in trends of oocyte developments and GSI changes. Testosterone levels of male H. nitens reached the highest value before and after the spent stage. Ovarian developmental stages of H. nitens could be classified into early growing stage, late growing stage, mature stage, ripe and spawning stage, recovery and resting stage. The testicular developmental stages could be divided into growing stage, mature stage, ripe and spent stage, and recovery and resting stage.

• 대한가정학회지
• /
• 제35권5호
• /
• pp.61-72
• /
• 1997

The purpose of this study was to examine the developmental changes about self-perception from childhood to adult period. The subjects were 365 of 5th graders in elementary school, the 2nd graders in junior and senior high school, sophomore in college, and adults. The instruments used for this study were Harter's Self-Perception Profile for the children, adolescences, college students, and adults. The results were as follows. 1. From elementary school to junior high school, the score of scholastic, athletic, physical appearance, behavioral conduct, and global self-worth were decreased. At the developmental perspective, the junior high school students were highly anxious for self-perception. 2. Physical appearance were the best predictor of the global self-worth for all developmental stages. 3. Physical appearance, behavioral conduct predicted more about the global self-worth than any other factors for elementary and junior high school students. And for junior high school students, social acceptance and friendship also predicted about the global self-worth. Scholastic competence showed higher correlation with global self-worth for the senior high school and college students than elementary and junior high school students. 4. For college students, males had higer scores than females on ability-oriented but also relationship-oriented subscales. But the adults showed no differences in nurturance, household management, job competence depending on sex.

• Molecules and Cells
• /
• 제43권7호
• /
• pp.600-606
• /
• 2020

Numerous physiological processes in nature have multiple oscillations within 24 h, that is, ultradian rhythms. Compared to the circadian rhythm, which has a period of approximately one day, these short oscillations range from seconds to hours, and the mechanisms underlying ultradian rhythms remain largely unknown. This review aims to explore and emphasize the implications of ultradian rhythms and their underlying regulations. Reproduction and developmental processes show ultradian rhythms, and these physiological systems can be regulated by short biological rhythms. Specifically, we recently uncovered synchronized calcium oscillations in the organotypic culture of hypothalamic arcuate nucleus (ARN) kisspeptin neurons that regulate reproduction. Synchronized calcium oscillations were dependent on voltage-gated ion channel-mediated action potentials and were repressed by chemogenetic inhibition, suggesting that the network within the ARN and between the kisspeptin population mediates the oscillation. This minireview describes that ultradian rhythms are a general theme that underlies biological features, with special reference to calcium oscillations in the hypothalamic ARN from a developmental perspective. We expect that more attention to these oscillations might provide insight into physiological or developmental mechanisms, since many oscillatory features in nature still remain to be explored.

• Animal cells and systems
• /
• 제3권1호
• /
• pp.97-102
• /
• 1999

In order to investigate the regional distribution and relative frequency of the serotonin-, somatostatin- and motilin-immunoreactive cells in the gastrointestinal tract GIT) of the bullfrog (Rana catesbeiana) with developmental stages, group of bullfrogs subdivided into the tadpole with hindlegs, metamorphosed bullfrog with tail, 2 wk after metamorphosed bullfrog and adult bullfrog, were stained by immunohistochemical methods (PAP methods). Multifarious changes of the regional distribution and relative frequency of the gastrointestinal endocrine cells were observed as developmental stages but motilin-immunoreactive cell ere not detected in this study. Serotonin-immunoreactive cells were detected from 2 wk after metamorphosed bullfrog in the whole GIT. The positive cells were predominant in the pylorus regions. In the adult bullfrog, these cells increased in fundus. On the other hand, somatostatin-immunoreactive cells were observed from the tadpole with hindlegs in the stomach regions. In the metamorphosed bullfrog with tail, they were found in the whole GIT except for the ileum, and increased with developmental stages except for rectum. In the rectum, these cells were not detected after that period. Our results show that most of the immunoreactive cells appear from completed metamorphosed periods when the histological structure of GIT is completely differentiated.

• 대한한방소아과학회지
• /
• 제31권1호
• /
• pp.82-91
• /
• 2017

These are three case reports on developmental delay that were treated with Korean medicine more than one year. A child with spastic cerebral palsy was treated only with acupuncture in one case, and in another case, two children with cerebral palsy were treated with both acupuncture and Korean herbal medication: Gami-Dossi-pyengwisan and Gami-Guibiondam-tang. After more than a year of treatment period, all three children showed improvement of general condition and motor function, measured by Gross Motor Function Measure, compare to average of children with cerebral palsy. According to this result, Korean medicine treatment can be helpful in improvement of spasticity and developmental delay due to cerebral palsy. Further studies with more cases and well-designed randomized controlled trials should be performed to establish proper guideline of Korean medicine treatment for cerebral palsy.

• 한국환경독성학회:학술대회논문집
• /
• 한국환경독성학회 2003년도 추계국제학술대회
• /
• pp.57-69
• /
• 2003

It is well known that many pesticides possess hormonal activity, and affect the developments of wildlife and mammals including human. Currently, pyrethroid insecticides are in worldwide use to control in and outdoor pests, providing potential far environmental exposure. Hormonal activities of these pyrethroid insecticides, however, have been little studied, and the developmental effects of them were no reported. Therefore, we firstly examined the potential estrogenic activities of some pyrethroid insecticides (permethrin, cypermethrin, tetramethrin, deltamethrin, sumithrin, fenvalerate and bioallethrin) by immature rat uterotrophic assay, luciferase reporter gene assay and Calbindin-D$\sub$9k/ (CaBP-9k) gene expression assay. Uterine wet weights were increased by permethrin and the permethrin-induced weights were inhibited by ICI 182780 in the uterolrophic assay. On the other hand tetramethrin significantly reduced uterine and vaginal wet weights, and also inhibited the E2-induced weight increases at all doses tested. Cypermethrin and sumithrin had a tendency to increase uterine weights, although not statistically significant. Permethrin and cypermethrin dose-dependently increased the luciferase activity in reporter gene assay. Northern blot analysis showed that permethrin induced CaBP-9k mRNA expression whereas tetramethrin inhibted. Subsequent studies were conducted to investigate the possible developmental effects of four pyrethroid insecricides (permethrin, cypermethrin, sumithrin and teramethrin). Either diethlbestrol (DES) or 17${\beta}$ -estradiol (E2) was used as a reference control in this study. Pyrethroid insecticides were administered to Sprague Dawley rats via subcutaneous injection at 6 to 18 days of gestation or 1 to 5 days after birth. In utero treatment of permethrin (10mg/kg/day) in female rat resulted in significant increases in uterine and ovarian weights while significant decreases in serum E2 concentration, uterine and ovarian ER${\alpha}$ mRNA levels. Sumithrin and permethrin led to acceleration in vaginal opening of female rat, while delay in preputial separation of male after neonatal treatment. Anogenital distances of PND 18 were significantly reduced in sumthrin-treated, and permerhrin-treated male rats after neonatal treatment. All the pyrethroid insecticides tested caused significant increases in uterine weights on PND 18, while significant reductions in the first diestrus phase when neonataly treated. In addition, exposure to pyrethroids in neonatal period led to significant reduction in relative brain weight in female rat on PND 18, but its weight was recovered in diestrus phase. In summary, Our experimental data demonstrate the possibilities of developmental effects of pyrethroid insecticides via estrogenic or antiestrogenic activity.

• Toxicological Research
• /
• 제22권2호
• /
• pp.127-133
• /
• 2006

Recently, we have reported that the environmental pollutant 2-bromopropane (2-BP) induces a significant embryo-fetal developmental toxicity in rats. However, the cause of developmental toxicity and the relationship between maternal and developmental toxicities could not be elucidated because the developmental toxicity of 2-BP was observed only in the presence of maternal toxicity The in vitro teratogenicity study using whole embryo culture was carried out to understand the teratogenic properties and the possible mechanism of teratogenicity induced by 2-BP in rats. Rat embryos aged 9.5 days were cultured in vitro for 48 hrs at medium concentrations of 0, 1, 3, or 10 mg/ml of 2-BP. Embryos were evaluated for growth, differentiation, and morphological alterations at the end of the culture period. At 10 mg/ml, 2-BP caused a delay in the growth and differentiation of embryos and an increase in the incidence of morphological alterations, including altered yolk sac circulation, abnormal axial rotation, craniofacial hypoplasia, open neuropore, absent optic vesicle and kinked somites. At 3 mg/ml, only a delay in the growth and differentiation of embryos was observed. There were no adverse effects on embryonic growth and development at the concentration of 1 mg/ml. The results showed that the exposure of 2-BP to rat embryos results in a developmental delay and morphological alterations at dose levels of 3 mg/ml culture media or higher and that 2-BP can induce a direct developmental toxicity in rat embryos.

• International Journal of Industrial Entomology and Biomaterials
• /
• 제45권2호
• /
• pp.115-125
• /
• 2022

In this study, we investigated the developmental characteristics and genetic diversity of seven populations of two-spotted crickets (Gryllus bimaculatus De Geer, 1773 (Orthoptera: Gryllidae)) raised in South Korea. Regarding the developmental characteristics of the species, we observed no statistically significant difference in the weight of the nymphs in the six populations we tested. After molting, although weight differences were observed between the populations in each stage of the developmental period, the average weight for each developmental stage was constant. We also analyzed mitochondrial COI gene sequences (DNA barcoding region) of the reared crickets collected from five insect farms and two national insect rearing facilities and the resultant sequences were analyzed together with the 12 sequences from foreign countries specimens obtained from public data. We detected six haplotypes from 111 specimens, indicating a low intraspecific genetic distance (~1.8%). The most dominant haplotype was overwhelmingly haplotype 1, which was found in all South Korean specimens and four specimens from China, Indonesia, and Germany. These findings indicate that the low genetic diversity of South Korean specimens can be explained by the fact that the G. bimaculatus population imported for feed from Japan in the early 2000s became a maternal group that spread throughout cricket farms in South Korea. In order to breed healthy cricket strains, it is necessary to increase genetic diversity by importing them from other countries through appropriate quarantine procedures.