• Journal of Photoscience
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• 제12권1호
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• pp.33-39
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• 2005

Plants possess the ability to dissipate the excitation energy for the protection of photosynthetic apparatus from absorbed excess light. Heat dissipation is regulated by xanthophyll cycle in thylakoid membranes of chloroplasts. We investigated the mechanistic aspects of xanthophyll cycle-dependent photoprotection against low-temperature photoinhibition in plants. Using barley and rice as chilling-resistant species and sensitive ones, respectively, chilling-induced chlorophyll fluorescence quenching, composition of xanthophyll cycle pigments and mRNA expression of the zeaxanthin epoxidase were examined. Chilled barley plants exhibited little changes in chlorophyll fluorescence quenching either of photochemical or non-photochemical nature and in the photosynthetic electron transport, indicating low reduction state of PS II primary electron acceptor. In contrast to the barley, chilled rice showed a marked decline in those parameters mentioned above, indicating the increased reduction state of PS II primary electron acceptor. In addition, barley plants were shown to have a higher capacity to elevate the pool size of xanthophyll cycle pigments in response to cold stress compared to rice plants. Such species-dependent regulation of xanthophyll cycle activity was correlated with the gene expression level of cold-induced zeaxanthin epoxidase. Chilled rice plants depressed the gene expression of zeaxanthin epoxidase, whereas barley increased its expression in response to cold stress. We suggest that chilling-induced alterations in the pool size of xanthophyll cycle pigments related to its capacity would play an important role in regulating plant's sensitivity to chilling stress.

• 환경생물
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• 제17권4호
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• pp.401-405
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• 1999

북방산개구리의 산란특성 및 발생과정을 연구하기 위하여 1998년 2월 중순에서 3월말까지 경기도, 경상북도, 강원도를 중심으로 남한의 전지역을 대상으로 표본을 채집하였다. 북방산개구리의 산란시기는 2월말에서 3월말사이에 주로 이루어지며, 산란장소는 정수지와 유수지를 모두 선택하나 유수지에 산란하는 경우 알의 형태는 뭉쳐진 불규칙한 공 모양으로 돌이나 수초와 같은 기질에 부착하며, 정수지의 경우 타원형의 계란모양을 이루고 기질에 부착하지 않는다. 발생과정은 산란 후 일주일이 지나면 대부분 부화하고 71일이 경과하면 전 발생과정을 완료한다. 발생과정이 비교적 짧은 것은 먹이원이 풍부한 계절에 적극적인 포식활동을 위한 것으로 판단된다.

• BMB Reports
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• 제47권9호
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• pp.475-482
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• 2014

Ubiquitin (Ub) is a versatile signaling molecule that plays important roles in a variety of cellular processes. Cellular Ub pools, which are composed of free Ub and Ub conjugates, are in dynamic equilibrium inside cells. In particular, increasing evidence suggests that Ub homeostasis, or the maintenance of free Ub above certain threshold levels, is important for cellular function and survival under normal or stress conditions. Accurate determination of various Ub species, including levels of free Ub and specific Ub chain linkages, have become possible in biological specimens as a result of the introduction of the proteomic approach using mass spectrometry. This technology has facilitated research on dynamic properties of cellular Ub pools and has provided tools for in-depth investigation of Ub homeostasis. In this review, we have also discussed the consequences of the disruption of Ub pool dynamics and homeostasis via deletion of polyubiquitin genes or mutations of deubiquitinating enzymes. The common consequence was a reduced availability of free Ub and a significant impact on the function and viability of cells. These observations further indicate that the levels of free Ub are important determinants for cellular protection.

• Parasites, Hosts and Diseases
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• 제55권2호
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• pp.129-135
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• 2017

A total of 60 samples were collected from 35 swimming pools in Beijing, China, and the presence of Cryptosporidium and Giardia were investigated. The results showed that 16.7% and 15.0% of samples were positive for Cryptosporidium oocyst and Giardia cysts, respectively, with a mean concentration of 0.30 oocysts/10 L and 0.27 cysts/10 L. The oocysts and cysts were found to have higher rates of occurrence in August than in May. Genotyping confirmed the presence of Cryptosporidium hominis, C. parvum, and Giardia assemblages A and B, all of which were associated with human infections. The predominant species/assemblages were C. hominis and Giardia assemblage A. Analyses of the relationships between parasite oocysts/cysts, indicator bacteria, and physical-chemical parameters revealed that there was no correlation between 2 parasites and fecal bacterial indicators, whilst there was a significant correlation between protozoa and urea concentration, which indicates that urea concentration rather than fecal bacterial indicators might be an appropriate index for chlorine-resistant protozoa in swimming pools. This study provides useful information to improve the safety of swimming pool water and deduce the risk of protozoan infections.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• 제2권1호
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• pp.53-61
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• 2021

Distribution of fish community depends largely on environmental disturbance such as habitat change. In this study, we evaluated the impact of environmental variables and microhabitat patch types on fish distribution in Yudeung Stream at 15 sites between early May and late June 2019. We used non-metric multidimensional scaling to examine the distribution patterns of fish in each site. Gnathopogon strigatus, Squalidus gracilis majimae, Zacco koreanus, and Zacco platypus were associated with riffle and boulder areas, whereas Iksookimia koreensis, Acheilognathus koreensis, Coreoleuciscus splendidus, Sarcocheilichthys nigripinnis morii, and Odontobutis interrupta were associated with large shallow areas. In contrast, Cyprinus carpio, Carassius auratus, Lepomis macrochirus, and Micropterus salmoides were found at downstream sites associated with large pool areas, sandy/clay-bottomed areas, and vegetated areas. On the basis of these results, we suggest that microhabitat patch types are important in determining the diversity and abundance of fish communities, since a mosaic of different microhabitats supports diverse fish species. As such, microhabitat patches are key components of freshwater stream ecosystem heterogeneity, and a suitable patch composition in stream construction or restoration schemes will support ecologically healthy food webs.

• 한국수산과학회지
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• 제40권1호
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• pp.39-49
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• 2007

Species competition among the toxic dinoflagellates Alexandrium tamarense and Gymnodinium catenatum and the diatom Skeletonema costatum was simulated using a mathematical model. Prior to the model simulation competition experiments using the three species were conducted to obtain data for validation by the simulation model. S. costatum dominated at a density of ${\sim}10^{4}\;cells/mL$ compared to the other species in the medium with dissolved inorganic phosphorus (DIP). The growth of S. costatum was also stimulated by the addition of dissolved organic phosphorus (DOP), such as uridine-5-monophosphate (UMP) or glycerophosphate (Glycero-P), although this species is unable to take up DOP. This implies that the growth of S. costatum may be supported by DIP, which is hydrolyzed by alkaline phosphatase produced from A. tamarense and G. catenatum. The species competition model was run assuming the environmental conditions of northern Hiroshima Bay, Japan, during spring and summer. G. catenatum increased in cell density and neared the level of S. costatum at the end of the calculation. In the sensitivity analyses by means of doubling and halving parameters, depleted DIP had little effect on the cell density of G. catenatum. However the growth of A. tamarense and S. costatum was significantly affected by changes in the parameter values. These results indicate that if DIP depletion is ongoing, species that have a large phosphate pool in their cells, such as G. catenatum, will predominate in the community.

• Preventive Nutrition and Food Science
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• 제16권4호
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• pp.313-320
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• 2011

The oxidative stress level and antioxidant activities in two green algae (Ulva pertusa and Ulva linza), two brown algae (Agarum cribrosum and Dictyota dichotoma), and three red algae (Grateloupia lanceolata, Carpopeltis affinis, and Gracilaria verrucosa) collected from intertidal regions of Korea were assessed. In the two green algae, although the total glutathione content was not as high as that of the brown algae, the glutathione pool was extremely reduced, and the glutathione reductase (GRd)/glutathione peroxidase (GPx) activity ratio was high, which apparently plays an important role for protection against oxidative damage, as manifested by low lipid peroxidation. In the brown algae, which exhibited a low lipid peroxidation level that was comparable to the green algal species, the highest glutathione content, together with high GPx activity, appears to be the most important factor in their antioxidant protection. The red algal species exhibited extremely high lipid peroxidation levels. They also contained the lowest and most oxidized glutathione among the species, as well as the lowest GRd activity. In spite of the marked difference in the glutathione content, the significant difference in the activity of ${\gamma}$-glutamylcysteine ligase, the rate limiting enzyme for glutathione synthesis, among the species was not exhibited. Our results suggest that there is a significant difference in the levels of oxidative stress and antioxidant capacity among the algal species, and that the glutathione system, especially the efficiency of glutathione recycling, plays a vital role in antioxidative protection in algal species.

• 한국어류학회지
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• 제17권2호
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• pp.142-147
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• 2005

새만금 방조제 축조에 따른 조간대 어류 군집의 변화를 알아보기 위해 조수웅덩이가 잘 발달된 전북 군산시 내초도와 전북 부안군 해창의 조수웅덩이를 대상으로 2002년부터 2004년까지 매월 어류를 채집하였다. 조사 기간 동안 채집된 어류를 기존의 자료와 비교 검토한 결과, 부안군 해창의 조수웅덩이에서 종의 수는 다소 감소하였으나, 두줄망둑 Tridentiger trigonocephalus가 우점종으로 나타난 점은 종전에 비해 변화가 없었다. 그러나 전북 군산시 내초도의 조간대에서는 종 수의 감소 외에도 우점종이 두줄망둑 T. trigonocephalus에서 풀망둑 Synechogobius hasta로 바뀌었고, 특히 모래 바닥을 서식처로 하는 날개망둑 Favonigobius gymnauchen의 감소현상이 뚜렷하였다. 한편 부안군 해창의 조간대에는 감성돔의 유어들이 본 조사 기간에도 다량 출현하고 있었지만, 내초도 조간대의 경우 1994년과 2000년에 조수웅덩이에서 다량으로 채집되었던 감성돔 Acanthopagrus schlegeli와 농어 Lateolabrax japonicus의 유어들이 채집되지 않았다. 결과적으로 내초도 조간대는 이들 어류의 성육장으로서의 기능이 갈수록 소실되어 가고 있는 것으로 판단되며, 이러한 전반적인 결과는 부안 해창에 비해 군산 내초도의 조간대가 펄에 의한 퇴적이 더욱 심하여 조간대 어류의 서식 환경이 크게 변하고 있기 때문으로 생각된다.

• The Korean Journal of Ecology
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• 제22권3호
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• pp.109-117
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• 1999

32종의 해안식물(주로 염생식물)에 대한 유리아미노산 및 총질소함량을 조사하였다. 몇몇 종(참골무꽃과 해란초)을 제외한 모든 식물체는 Pro을 함유하였으나, 번행초, 등골나물아재비 및 갯무에서만, 높은 함량을 나타내어, 이들 식물에서 Pro은 세포질성 삼투물질로 작용하는 것으로 생각된다. 그러나 등대풀, 갯무, 갯방풍, 갯기름나물, 통보리사초, 왕잔디, 갯잔디 등의 식물은 Pro 보다는 hydroxylproline (OH-Pro)을 상당량 축적하였다. 총 아미노산은 갯개미취, 갯질경, 해란초, 순비기나무 및 특히 명아주과와 돌나물과 식물에서 낮은 값을 보였다. 또한 번행초, 등대풀, 갯무, 명아주과 및 콩과 식물은 보편적으로 총 질소 및 수용성 질소함량이 높았으나, 참골무꽃, 해란초, 순비기나무, 통보리사초 및 벼과 식물은 낮은 수준의 질소함량을 보였다. 대부분의 해안식물에서 유리아미노산은 총질소함량에 차지하는 비율이 낮았지만, 등대풀, 모래지치 및 둥근바위솔의 경우 아미노산 질소가 총질소함량의 25∼30%를 차지하였다. 결론적으로, 몇몇 예외는 있지만 세포질성 삼투물질로 널리 알려진 Pro은 조사된 해안식물의 유리아미노산 풀(pool)에서 유의한 몫을 차지하지 않는 것으로 여겨진다.

• Asian-Australasian Journal of Animal Sciences
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• 제13권7호
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• pp.922-928
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• 2000

The effects of animal species and supplements on rumen fluid characteristics, plasma urea-N (PUN) concentration, plasma urea-N pool size, urea-N degradation in the gut and urea-N net flux (urea-N synthesis rate) were studied in goats and sheep, with some minor differences detected. The animals were fed either chopped rice straw ad libitum+200 g soybean meal (SBM), or chopped rice straw ad libitum+190 g soybean meal+300 g sago meal (SBM+SM) for 14 days. The supplements were isonitrogenous (80 g crude protein/animal/d). [$^{14}C$]-urea was used as the marker for urea metabolism studies. Two animals from each species were fed either supplement in a cross-over design in two periods. The results showed that rumen pH was significantly (p<0.001) lower in animals fed SBM+SM than those fed SBM supplement. The ammonia concentrations of rumen fluid were significantly (p<0.01) higher in sheep (382.9 mg N/L) than goats (363.1 mg N/L) when fed SBM supplement but lower (282.5 mg N/L) than that of goats (311.0 mg N/L) when fed SBM+SM supplement. Total VFA concentrations were significantly (p<0.05) higher in animals fed SBM+SM supplement than those fed SBM supplement. Goats had significantly (p<0.01) higher molar proportions of acetate (79.1, 77.7%, respectively) than sheep (75.8, 74.0%, respectively) in both supplements. The molar proportion of acetate was significantly (p<0.05) higher, while that of butyrate lower in animals fed SBM supplement than those fed SBM+SM supplement. In animals fed SBM supplement, the molar proportion of propionate was significantly (p<0.01) higher in sheep (18.0%) than in goats (15.6%), but in animals fed SBM+SM, the molar proportion of butyrate was significantly (p<0.01) higher (9.6%) in sheep than in goats (7.2%). Plasma urea-N concentration, plasma urea-N pool size, urea-N degradation in the gut, urea-N net flux and the fraction of urea-C from the blood entering the rumen were not significantly different between goats and sheep fed either supplement. However, PUN concentration was significantly (p<0.05) lower in animals fed SBM+SM supplement (average of 13.8 mg N/100 ml) than in those fed SBM supplement (average of 16.5 mg N/100 ml). The urea net flux was significantly (p<0.05) higher in goats (average of 14.5 g N/d) than sheep (average of 12.9 g N/d), and animals fed SBM supplement showed higher (average of 14.9 g N/d) urea net flux than animals fed SBM+SM supplement (average of 12.9 g N/d). A significant (p<0.05) positive correlation was observed between urea-N net flux and urea-N degradation; urea-N net flux and pool size; urea-N net flux and urea excretion in the urine; and PUN and rumen ammonia in goats. While in sheep, significant (p<0.05) positive correlation was observed between urea-N net flux and urea excretion in the urine; and PUN and rumen ammonia.