• 대기
• /
• 제16권4호
• /
• pp.269-278
• /
• 2006

Extremely hot weathers may cause major weather-related deaths in the summertime. Influences of heat waves on daily mortalities in 6 major cities of South Korea were investigated. Daily deaths at Seoul were exponentially increased with the daily maximum temperature. However, there were regional differences of the temperature dependence on the mortality because of an acclimation effect of inhabitants. The threshold temperature (with respect to daily maximum temperature) at Seoul was found to be about $31^{\circ}C$ provided that it is determined by a two-phase regression model. The meteorological causes of recordable hot summer in late July of 1994 and their impacts on human health were also investigated. Strong surface heating caused by strong insolation under conditions with clear sky and dry surface due to prolonged drought was likely to be closely associated with the extreme hot weather in 1994 in South Korea.

• 한국패류학회지
• /
• 제25권2호
• /
• pp.93-96
• /
• 2009

Unexpected mass mortality has been one of the drawbacks in front of the stable production of Japanese scallop (Patinopecten yessoensis) on the Gangwon coasts of the East Sea. The preliminary data from our routine observation revealed that the mortality appeared to be related to variation of water temperature in the farming site and the degree of the mortality was dependent on scallop strain. The present study performed to verify the preliminary findings exhibited that the mortality was closely related to daily temperature variation rather than monthly variation. Daily temperature variation was particularly damageable to the scallop during the temperature elevation period. Scallops from hatchery seeds (Chinese strain) were more tolerant against the temperature variation over those from wild seeds. The hatchery scallop gain of the temperature tolerance was probably due to their larval experience to higher temperature in the hatchery as well as their maternal genetic acclimation to upper temperature extreme of the Chinese environment which was recently found.

• Journal of Ginseng Research
• /
• 제32권4호
• /
• pp.347-356
• /
• 2008

Forest-grown American ginseng (Panax quinquefolius L.) is exposed to daily and seasonal light variations. Our goal was to determine the effect of understory light changes on the maximum quantum yield of photosystem II, expressed as $F_v/F_m$, and photosynthetic pigment composition of two-year-old plants. Understory light photon flux density and sunfleck durations were characterized using hemispherical canopy photography. Our results showed that understory light significantly affected the $F_v/F_m$ of American ginseng, especially during the initial development of the plants when light levels were the highest, averaging 28 mol $m^{-2}d^{-1}$. Associated with low $F_v/F_m$ during its initial development, American ginseng had the lowest levels of epoxidation state of the xanthophyll cycle of the season, suggesting an active dissipation of excess light energy absorbed by the chlorophyll pigments. As photon flux density decreased after the deployment of the forest canopy to less than 10 mol $m^{-2}d^{-1}$, chlorophyll a/b decreased suggesting a greater investment in light harvesting pigments to reaction centers in order to absorb the fleeting light energy.

• 한국작물학회:학술대회논문집
• /
• 한국작물학회 2017년도 9th Asian Crop Science Association conference
• /
• pp.5-5
• /
• 2017

Too little and too much water due to climatic events is a significant cause of global food insecurity. Crops are less productive under water-limited conditions and all major crops, with the exception of rice (Oryza sativa), die within a few days of complete submergence. To complement our studies on genes such as SUB1A, (an ERF-VII transcription factor that provides robust submergence tolerance) and AG1 (a TREHALOSE 6-P PHOSPHATASE that promotes establishment of young seedlings underwater), we have retooled INTACT (${\underline{I}}solation$ of ${\underline{N}}uclei$ ${\underline{TA}}gged$ in specific ${\underline{C}}ell$ ${\underline{T}}ypes$) and TRAP (${\underline{T}}ranslating$ ${\underline{R}}ibosome$ ${\underline{A}}ffinity$ ${\underline{P}}urification$) for rice. These technologies enable us to follow dynamics in chromatin, nuclear pre-mRNAs and ribosome-bound mRNAs in meristems and diverse cell types. With these technologies we can better interpret responses to stresses and reestablishment of homeostasis. These include stress acclimation strategies involving changes in metabolism and development, such as dynamics in suberin deposition in sub-epidermal layers of roots that limit water loss under drought and oxygen escape during waterlogging. Our new data uncover dynamic and reversible regulation at multiple levels of gene regulation and provide new insights into processes of stress resilience. Supported by US NSF-PGRP Plasticity (IOS-1238243), Secretome (IOS-1546879) and REU (DBI-146129) grants.

• 대한두개안면성형외과학회지
• /
• 제16권2호
• /
• pp.73-79
• /
• 2015

Background: Alprostadil and sildenafil are known vasodilators used independently to improve flap survival in animal models. In this study, we investigate whether these agents act synergistically to decrease flap necrosis in rat models. Methods: After acclimation period, 4 groups of 10 male white rats were given a modified McFarlane skin flap. The postoperative treatment included saline control (Group A), sildenafil citrate-only (Group B), alprostadil-only (Group C), and both sildenafil and alprostadil (Group D). The flaps were observed on postoperative days 1, 3, 5 and 7. The animals were euthenized on postoperative day 7, and the flaps were evaluated for inflammation and neovascularization. Results: At each observation, the mean necrotic index was significantly lower for all three treatment groups (Groups A, B, C) and was the lowest for the combined treatment group. On histologic evaluations, combined treatment was associated with decreased inflammation and increased capillary vessel formation, when compared with control group. Conclusion: Both sildenafil-only and alprostadil treatments were independently associated with increased flap survival rate. Sildenafil citrate and alprostadil had a synergistic effect in increasing flap survival rate.

• 한국패류학회지
• /
• 제17권2호
• /
• pp.95-104
• /
• 2001

To determine optimal conditions for measurement of the clearance rate in feeding experiment of an intertidal bivalve Glauconome chinensis, effects of starvation, extent of mixing at subsampling, and initial prey concentration were assessed. Experiments were conducted separately for each condition with different treatments. Two-way ANOVAs showed that there were significant differences in clearance rates among different starvation periods (p<0.001), extents of mixing (p = 0.005), and prey concentrations (p < 0.001). Starvation for 1 or 2 days gave rise to 2 to 3-fold increase in the clearance rate. After starvation for 5 days, the clearance rate decreased seriously, implying loss of physiological status. It is suggested that animals should be fed during acclimation. The differences of the clearance rates between gentle and vigorous mixings were significant, but the differences were smaller than that among different incubation times. It was found that vigorous mixing is not necessary. The effect of initial prey concentration was great. However, optimal prey concentration could not be determined at any fixed value. Experiments with multiple concentrations of algal prey are recommended. Optimal incubation time for measurement of the clearance rate of G. chinensis was determined to be 2-4 hours.

• 한국발생생물학회지:발생과생식
• /
• 제23권4호
• /
• pp.345-353
• /
• 2019

Higher thermal exposure can influence the blood cell morphology and count. Hence, based on the previous results (Rahman et al., 2019), the present study evaluated the morphometric indices of erythrocytes and their nucleus under different water temperatures (25℃, 28℃, 31℃, and 34℃) to investigate their use as an indicator of thermal stress in red spotted grouper, Epinephelus akaara. 180 healthy specimens of E. akaara were exposed to four temperature conditions (25℃ as control, 28℃, 31℃, and 34℃) for 42 days, following 2 weeks of acclimation at 25℃. Erythrocyte major axis (EL), erythrocyte minor axis (EW), nucleus major axis (NL), and nucleus minor axis (NW) were examined from the blood smears on each sampling day (i.e., 2, 7, and 42 days of thermal exposure). EL and NL were significantly decreased, whereas EW and NW were increased at higher water temperature (31℃ and 34℃). The major-minor axis proportions of erythrocytes and their nucleus (EL/EW; NL/NW) were decreased with increasing water temperature (31℃ and 34℃). The strong relationships were observed among the morphometric indices of erythrocytes and their nucleus, especially in EL vs. NL and EW vs. NW. This study reveals that elevated water temperature (31℃ and 34℃) can influence the major and minor axis morphometry of erythrocytes and their nucleus in red spotted grouper. These indices may be used as stress indicators to monitor the health status of E. akaara and probably for other fish species.

• 한국축산시설환경학회지
• /
• 제20권4호
• /
• pp.147-154
• /
• 2014

Heat stress is a significant burden to animal production in most areas of the world. Improving our knowledge of physiological and metabolic mechanisms of acclimation may contribute to the development of procedures that may help to maintain health and production efficiency under hot temperature. The effect of Ulmus pumila (UP) extract in inducing Heat Shock Proteins (HSPs) expression in heat-stressed RAW264.7 macrophage cells was investigated. Cell viability assay showed a dose dependent increase in cells after treatment with UP for 24 hours. RT-PCR and western blot analysis showed that increasing concentrations of UP induce the expression of Heat Shock Factor 1 (HSF1) and dose dependently upregulated the expression of Heat shock protein 70 (Hsp70) and Hsp90. LPS-induced nitric oxide was dose-dependently reduced while phagocytic activity greatly recovered with UP treatment. These data demonstrated that UP can be a potential candidate in the development of cytoprotective agent against heat stress.

• Ocean and Polar Research
• /
• 제38권2호
• /
• pp.103-113
• /
• 2016

This study aimed to examine the role of two aquaporin isoforms (AQP3 and AQP8) in response to the hyperosmotic challenge of transitioning from freshwater (FW) to seawater (SW) during parr and smoltification (smolt) using the rainbow trout, Oncorhynchus mykiss. We examined the changes in the expression of AQPs mRNAs in the gills and intestine of the parr and smolt stages of rainbow trout transferred from FW to SW using quantitative real-time PCR in an osmotically changing environment [FW, SW, and recombinant AQP3 (rAQP3) injection at two dosage rates]. Correspondingly, AQPs were greater during smoltification than during parr stages in the rainbow trout. Plasma osmolality and gill $Na^+/K^+$-ATPase activity increased when the fish were exposed to SW, but these parameters decreased when the fish were exposed to SW following treatment with rAQP3 during the transition to seawater. Our results suggest that AQPs play an important role in water absorbing mechanisms associated with multiple AQP isoforms in a hyperosmotic environment.

• Journal of Microbiology and Biotechnology
• /
• 제22권7호
• /
• pp.902-906
• /
• 2012

Expressed sequence tags (ESTs) from the Antarctic green algae Pyramimonas gelidicola were analyzed to obtain molecular information on cold acclimation of psychrophilic microorganisms. A total of 2,112 EST clones were sequenced, generating 222 contigs and 219 singletons, and 200 contigs and 391 singletons from control ($4^{\circ}C$) and cold-shock conditions ($-2^{\circ}C$), respectively. The complete EST sequences were deposited to the DDBJ EST database (http://www.ddbj.nig.ac.jp/index-e.html) and the nucleotide sequences reported in this study are available in the DDBJ/EMBL/GenBank. These EST databases of Antarctic green algae can be used in a wide range of studies on psychrophilic genes expressed by polar microorganisms.