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Growth and Survival Rates of Flat Oyster, Ostrea denselamellosa, by Condition of Larval Cultivation (벗굴 (Ostrea denselamellosa) 유생의 생육조건에 따른 성장과 생존)

  • Yang, Moon-Ho;Oh, Bong-Se;Han, Chang-Hee
    • The Korean Journal of Malacology
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    • v.19 no.2
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    • pp.133-142
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    • 2003
  • For the effective seedling production of flat oyster, Ostrea denselamellosa, dietary value of live food, densities, water temperature and salinity on growth and survival rate of the larvae were examined. In rearing larvae by feeding them phytoplankton diets, the optimal survival rate and growth rate of larvae were found using a mixed phytoplankton diet which was mixed with Isochrysis galbana, Chaetoceros calcitrans and Chlorella sp. The highest growth and survival rates of the larvae were 208.4% and 38.8% with the phytoplankton diet. In growth and survival rates of larvae with various rearing densities, the highest survival and growth rates were 228.1% and 29.0% at the density of 2 individuals/ml. In observing rearing experiments of the flat oyster larvae under various temperature conditions, average growth rates of the larvae in respect to shell length were 202.2%, 240.4%, 250.6% and 121.3% in natural water temperatures (18-22$^{\circ}C$), 24$^{\circ}C$, 28$^{\circ}C$ and 32 $^{\circ}C$, respectively. And average survival rates of the larvae were 16.0%, 32.0%, 13.0% and 0% in natural water temperatures (18-22$^{\circ}C$), 24$^{\circ}C$, 28$^{\circ}C$ and 32$^{\circ}C$, respectively. In rearing at various salinities, the highest growth rates of the larvae in shell length was 240.0% at 30.0 psu and the highest survival rate was 31.0% at 25 psu.

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A Study of Analysis on Comparison of Laying Performance and Disease Occurrence of Welfare Approved Farms of Laying Hens with Housing Type (산란계 동물복지 인증농가의 사육형태와 품종별 생산성 및 질병발생 비교 분석 연구)

  • Hong, Eui-Chul;Kang, Hwan-Ku;Park, Ki-Tae;Jeon, Jin-Joo;Kim, Hyun-Soo;Park, Sung-Bok;Kim, Chan-Ho;Suh, Sang-Won;Kim, Sang-Ho
    • Korean Journal of Poultry Science
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    • v.44 no.2
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    • pp.143-149
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    • 2017
  • This study was carried out to collect basic data on the egg laying performance and disease occurrence on animal welfare-approved farms (AWAF) for laying hens with different housing types (windowless, open, and free-range house) and strains (Hy-line, Lohmann). Age at first egg laying was 151 d in the windowless house and 141 d in both the open and free-range houses, and the percentage peaks of each farm were 91.8%, 92.9%, and 86.3%. Average egg production according to housing types were 70.9%, 77.4%, and 65.6% at 18~38 wk old and 91.1%, 90.1%, and 76.2% at 32~36 wk. The average dirty and cracked egg ratio of the windowless, open, and free-range houses was 2.84%, 1.15%, and 0.23%, respectively. Mortality in the open house was lower than the other house types. Age of first egg laying for the Hy-line strain was 155 d and that for the Lohmann strain was 157 d, and the percentage peaks of the two strains were 92.9% (252 d) and 87.2% (237 d), respectively. Average egg production of the strains was 83.7% and 76.9%, respectively. The average dirty and cracked egg ratio of the Hy-Line and Lohmann strains was 3.85% and 2.97%, respectively. Mortality of the Hy-Line strain was lower than that of the Lohmann strain. There were significant differences (P<0.05) in the egg weight, HU, and egg yolk color of chickens raised in the open house compared with those of chickens raised in the other house types. In terms of antibody titer, that for Newcastle disease in open house chickens was lower than that of chickens raised in windowless and free-range houses. The antibody titer for low pathogenic avian influenza, avian infectious bronchitis, and avian pneumovirus was high at over 3.0 in all three farms. SG, Salmonella enteritidis, Salmonella pullorum, fowl adenovirus infection, and infectious laryngotrachitis were not detected in any of the three house types. The number of AWAF for laying hens has continuously increased in Korea, but there is currently little data on the housing types used on the AWAF for laying hens. Therefore, the results of the present study, in which analyzed the laying performance and disease occurrence on AWAF for laying hens, can use as basic data for the improvement of performance and prevention of disease on further AWFA for laying hens.

Bioecological Characteristics of Coral Habitats around Moonsom, Cheju Island, Korea I. Environment Properties and Community Structures of Phytoplankton (제주도 문섬 산호서식지 주변의 생물생태학적 특성 I. 환경특성과 식물플랑크톤의 군집구조)

  • Choa, Jong-Hun;Lee, Joon-Baek
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.5 no.1
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    • pp.59-69
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    • 2000
  • Environmental factors and phytoplankton community have been bimonthly investigated in order to clarify the bioecological characteristics of coral habitats around Moonsom at the southern Cheju Island from September 1995 to July 1996. Annual mean temperature and annual mean salinity were $17.4^{\circ}C$ and 34.06 psu, respectively, showing lower temperature-higher salinity in winter and higher temperature-lower salinity in summer, which means such conditions are inadequate for coral reef formation. Nutrient concentrations represent that total nitrogen ranged from $0.07{\sim}10.08\;{\mu}M$, phosphate from $0.05{\sim}1.70\;{\mu}M$, and silicate from $3.08{\sim}21.86\;{\mu}M$. The N/P ratio showed the range of 9.59-10.60 with decreasing offshore-ward, which means the phytoplankton community could be limited by nitrogen sources. Annual mean euphotic depth was 32.0m (18.9m-48.6m) with difference according to season and reveals the close relationship with the depth of coral distribution. Chlorophyll a concentrations of phytoplankton ranged from $0.12{\sim}1.51\;{\mu}g\;L^{-1}$ and standing crops from $1.5{\times}10^3{\sim}7.0{\times}10^5\;cells\;L^{-1}$, showing higher at inshore than at offshore with a blooming in May. A total of 128 species of phytoplankton occurred in all stations, representing 99 spp. of diatoms, 26 spp. of dinoflagellates, 2 spp. of silicoflagellates and 1 sp. of blue-green algae. Diatoms are main taxa in all seasons except for occupying by dinoflagellates in summer. Among dominant species, fParalia sulcata (Ehrenberg) Cleve and Cylindrotheca closterium (Ehrenberg) Lewin & Reimann were predominant and are likely to be main food sources for coral community. Annual mean species diversity index (H') was 1.84, showing lower than around the coast line of Cheju Island.

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Antioxidative and Antimicrobial Activities of Lilium Species Extracts Prepared from Different Aerial Parts (부위별 식용백합 추출물의 항산화 및 향균효과)

  • Joung, Yong-Myeon;Park, Soo-Jin;Lee, Ki-Young;Lee, Ji-Yong;Suh, Jeung-Keun;Hwang, Seong-Yun;Park, Kyoung-Eun;Kang, Myung-Hwa
    • Korean Journal of Food Science and Technology
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    • v.39 no.4
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    • pp.452-457
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    • 2007
  • In this study, Lilium sp. were separated into bulbs, leaves, and flowers. Then, total polyphenol contents, electron donating ability (EDA), superoxide dismutase (SOD)-like activity, hydroxyl radical scavenging activity, and antimicrobial activity were measured from the extracts of each of the three aforementioned parts. The examination of physiologically active substances in the three parts revealed that Lilium davidii leaves had high total polyphenol contents, SOD-like activity, hydroxyl radical scavenging activity, and EDA, while the flowers of L. lancifolium showed high SOD-like activity, hydroxyl radical scavenging activity, and EDA, as well as a high level of total polyphenols in the bulb. Measurements of the antimicrobial activities of the extracts against Gram positive bacteria revealed that the leaves and flowers of L. davidii and L. lancifolium caused Bacillus subtilis and Salmonella enteritidis to form clear zones greater than 10 mm. Furthermore, the flowers of L. lancifolium showed particularly high antimicrobial activity against B. subtilis, and the flowers of L. davidii had high activity against S. enteritidis. For the Gram negative bacteria, the leaves and flowers of L. davidii and L. lancifolium caused Listeria monocytogenes and Escherichia coli to form clear zones greater than 10 mm, and finally, the flowers of L. davidii and L. lancifolium showed high antibacterial activity, with inhibition exceeding 12 mm.

Microbiological Study and Isolation of the Vibrio vulnificus in the Sea Water, Sediment, Fish and Shellfish, Kithen Environment of Chunnam Coastal Area (전남 해안지역의 해수, 개펄, 수족관내 어패류 및 주방환경에서 장염 패혈증균(Vibrio vulnificus)의 분리와 미생물학적 연구)

  • Park, Kyung-Soo;Han, Chul;Suk, Keun-Young;Jung, Hae-Chang;Kim, Young-Hui;Kim, Chun-Kyu
    • Korean Journal of Food Science and Technology
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    • v.25 no.5
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    • pp.449-455
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    • 1993
  • Vibrio vulnificus is a recentry recognized halophilic organism that may cause human infections. Patients infected with Vibrio vulnificus often have a history of exposure to the sea, suggesting that the organism may be common inhabitant of marine environment. In this studies 314 samples were collected from 9 sites of Chonnam coastal area, from April to Jun, 1993. Isolation rates of V. vulnificus were 7.1% in total samples, 33.3% in sea water, 55.5% in sediment, 1.7% in fish and shellfish, 6.3% in kitchen environment. In each areas of Chunnam V. vunificus were isolated from 3.6% to 11.4%. The isolation rates of V. vulnificus was correlated positively with organic matter and COD in sea warer and sediment. In sea water, Microorganism population were $4.5{\times}10^3{\sim}3.5{\times}10^5\;CFU/ml$, Vibrio strains were $1.8{\times}10^l4.6{\times}10^3\;CFU/ml$, Coliform bacteria were $1.9{\times}10^1{\times}3.7{\times}10^2\;CFU/100ml$. In sediment, Microorganism population were $4.8{\times}10^3{\sim}5.2{\times}10^5\;CFU/ml$. Vibrio strains were $1.9{\times}10^2{\sim}8.4{\times}10^4\;CFU/ml$, Coliform bacteria were $7.2{\times}10^1{\sim}9.9{\times}10^2\;CFU/100ml$.

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Le Lien de Causalit$\acute{e}$ et la Prescription Extinctive en Mati$\acute{e}$re de Responsabilit$\acute{e}$ M$\acute{e}$dicale en Droit Français (프랑스법상 의사책임분야(醫事責任分野)에서의 인과관계와 소멸시효론에 관한 소고)

  • Park, Soo-Gon
    • The Korean Society of Law and Medicine
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    • v.15 no.2
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    • pp.367-397
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    • 2014
  • Dans le contentieux m$\acute{e}$dical, il est difficile de prouver l'existence d'un lien de causalit$\acute{e}$ entre la faute m$\acute{e}$dicale et les pr$\acute{e}$judices subis par la victime. R$\acute{e}$partir bien de façon raisonnable la charge de la preuve du lien causal est alors une des questions pr$\acute{e}$occup$\acute{e}$es par la doctrine cor$\acute{e}$enne. La Cour supr$\hat{e}$me cor$\acute{e}$enne semble toutefois facilliter l'indemnisation des victimes dans les cas o$\grave{u}$ la responsabilit$\acute{e}$ du m$\acute{e}$decin a ${\acute{e}}t{\acute{e}}$ mise en cause, et cela en admettant des fois une solution op$\acute{e}$rant un renversement de la charge de la preuve du lien causal. Une telle attitude a ${\acute{e}}t{\acute{e}}$ m$\hat{e}$me affirm$\acute{e}$e dans un arr$\hat{e}$t rendu r$\acute{e}$cemment en cas de dommage caus$\acute{e}$ par le fait du produit de sant$\acute{e}$, notamment pour le cas de contamination virale par voie de transfusion. La Cour a $\acute{e}$galement reconnu que l'action se pr$\acute{e}$scrit $\grave{a}$ partir du moment de la consolidation du pr$\acute{e}$judice. Aux termes de cette $\acute{e}$tude, on pourra constater que le juge français reconna$\hat{i}$t aussi l'assouplissement de la charge de la preuve du lien de causalit$\acute{e}$ en mati$\acute{e}$re d'action m$\acute{e}$dicale. Il faudra toutefois souligner que le ph$\acute{e}$nom$\acute{e}$ne ne soit pas g$\acute{e}$n$\acute{e}$ralis$\acute{e}$ en droit français, d'autant plus que la pr$\acute{e}$somption de l'existence de la causalit$\acute{e}$ en la mati$\grave{e}$re a $\acute{e}$t$\acute{e}$ admise de mani$\grave{e}$re restrictive par la l$\acute{e}$gislation sp$\acute{e}$cifique. Tel $\acute{e}$tait notamment le cas pour les accidents de la contamination par le virus du sida ou de l'h$\acute{e}$patite C survenus apr$\grave{e}$s la transfusion. En d$\acute{e}$finitive, on peut dire qu'en droit français, le principe est maintenu en cas de manquement $\grave{a}$ une obligation de r$\acute{e}$sultat n$\acute{e}$e du contrat m$\acute{e}$dical, tandis que la Cour de cassation admet parfois en mati$\grave{e}$re de droit commun de la responsabilit$\acute{e}$ contractuelle la pr$\acute{e}$somption de causalit$\acute{e}$ en cas d'inex$\acute{e}$cution des obligations de r$\acute{e}$sultat. En fait, la pr$\acute{e}$somption de causalit$\acute{e}$ dans le contentieux m$\acute{e}$dical pourra mener les m$\acute{e}$decins $\grave{a}$ se diriger vers les traitements d$\acute{e}$fensifs. Cette situation peut m$\hat{e}$me conduire $\grave{a}$ emp$\hat{e}$cher le d$\acute{e}$veloppement de la science m$\acute{e}$dicale, enfin $\grave{a}$ une situation d$\acute{e}$savantageuse aux patients. Il y a alors lieu de se m$\acute{e}$fier des int$\acute{e}$r$\hat{e}$ts d$\acute{e}$s$\acute{e}$quilibr$\acute{e}$s entre le m$\acute{e}$decin et le patient. De ce point de vue, on peut estimer que le droit français donne des suggestions aux juristes cor$\acute{e}$ens dans la recherche des solutions plus ad$\acute{e}$quates en ce qui concerne la charge de la preuve du lien causal en mati$\acute{e}$re de responsabilit$\acute{e}$ m$\acute{e}$dicale.

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Effect of Biozyme on Alcohol Metabolism

  • Park, Seung-Hee;Nam, Suk-Woo;Sungpil Yoon;Minsik Son;Nam, Tae-Kyun;Seo, Dong-Wan;Sungyoul Hong;Lee, Hyang-Woo
    • Proceedings of the Korean Society of Applied Pharmacology
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    • 1995.04a
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    • pp.91-91
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    • 1995
  • 에탄올에 의한 급성독성은 에탄올, 아세트알데히드 및 에탄을 대사산물의 변형생성물질 등에 기인하므로 알콜 섭취 후 혈중 에탄을 농도 및 아세트알데히드의 농도를 낮추는 것은 음주에 의한 급성 중독상태에 머무는 시간을 단축시키는데 중요하다. 본 실험에서는 Bacillus subtilis natto sp.를 식물 추출액을 배지로 하여 배양한 후 단백 분해효소로 고분자물질을 절단하여 얻은 발효액인 바이오짐(상품명: Biozyme)을 주성분으로 한 '비지니스(조선무약합자회사)' 의 인체 혈중 알콜대사 촉진작용을 검색하였으며, 비지니스 및 바이오짐이 랫드의 에탄을 대사에 미치는 효과를 검토하여 다음과 같은 결과를 얻었다. 인체 혈중 알콜대사 촉진작용을 검색하기 위해 알콜 섭취 전과 후의 혈중 에탄올 농도를 비교하였는데, 대조군에 비해 비지니스 투여군이 30분 후부터 2시간 후까지 혈청 알콜농도가 낮게 나타났다. 대조군의 혈청 알콜농도를 100으로 하였을 때 알콜 투여 30분, 60분, 90분, 120분 경과 후 시험군은 각각 대조군의 84.3%, 89,0%, 85.9%, 75.8%를 나타내어 평균 16% 정도 낮았다. 시험군의 AUC는 대조군의 AUC의 89%로 비지니스 투여군에서 혈액내 알콜의 제거가 빠르게 진전된다는 것을 보여주었다. 또한, 랫드의 에탄을 대사에 미치는 효과를 알아보고자 바이오짐 및 비지니스 투여 후 채혈하여 혈중 에탄을 및 아세트알데히드 농도를 측정하였다. 비즈니스 투여시 혈중 알콜 농도는 알콜 투여 60분 경과후 가장 큰 감소 효과(대조군:83.70$\pm$11.80mg/이, 시험군:45.12$\pm$6.63mg/d1, 47% 감소)를 나타내었으며, 시험군의 AUC는 대조군에 비해 30% 감소하였다. 혈중 아세트알데히드 농도는 투여 60분 후 비지니스 투여군(4.56$\pm$0.51nmol/$m\ell$)이 대조군(6.45$\pm$0.64nmo1/$m\ell$)에 비해 유의성 있는 감소(29%)를 나타내었으며, 시험군의 AUC는 대조군에 비해 35% 감소하였다. 바이오짐 투여시 혈중 에탄을 농도가 알콜 투여 2시간 경과 후 가장 큰 감소 효과(대조군:49.10$\pm$5.20mg/dl, 시험군:25.90$\pm$7.16mg/d1, 47% 감소)를 나타내었으며, 시험군의 AUC는 대조군에 비해 39% 감소하였고, 혈중 아세트알데히드의 농도는 투여 60분후 시험군(3.96$\pm$0.07nmo1/$m\ell$)이 대조군(6.45$\pm$0,64nmo1/$m\ell$)에 비해 유의성 있는 감소(39%)를 나타내었으며, 시험군의 AUC는 대조군에 비해 48% 감소하였다 한편, 시험관내 에탄올 대사 효소에 대한 바이오짐의 효과를 검색해본 결과 바이오짐(2.0 $\mu\textrm{g}$/assay)에 의해 Aldehyde dehydrogenase(1.5unit/assay)의 활성이 14% 증가되었다. 본 연구의 결과로 볼 때, 비지니스 및 바이오짐은 음주 후 상승된 혈중 에탄을 농도 및 아세트알데히드의 농도를 현저히 감소시키는 효과가 있었다.

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Field Bioassays On Shellfish To Assess Environmental Pollution Levels Of The Masan Bay (마산만(馬山灣)의 환경오염(環境汚染) 평가(評價)를 위한 야외(野外) 생물(生物) 오염(汚染) 시험(試驗) 연구(硏究))

  • Park, Joo-Surk
    • 한국해양학회지
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    • v.14 no.1
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    • pp.15-25
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    • 1979
  • A study on field bioassay test using four species of commercially important shellfish was carried out to assess the effect of pollutants and determine the extent of marine environmental pollution of the Masan Bay from 9 to 15 August 1978. Water quality analysis and planktological examination of sea water were made during the experiment and the examination gave the following results. The water temperature was so high at 31.7$^{\circ}C$ in maximum and rather subject to change on weather condition of the land than on the effect of the water mass from outer bay. The range of DO,COD and SS at the stations were 0.3-7.08cc/l, 0.07-3.31ppm and 5.5-117ppm, respectively with the high values of COD and SS at the stations 7 and 1. The concentrations of the dissolved inorganic nitrogen in sea water, NH$\sub$4/-N, NO$\sub$2/-N, NO$\sub$3/-N, and PO$\sub$4/-P were 18.90-99.80, 2.48- 19.60, 13.00-39.00 and 1.04-14.0$\mu\textrm{g}$ at/l, respectively with decrease of their values in the outer part of the Bay. The high values mentioned above were caused by the sewage and industrial activities. The effects of organic waste are increased oxygen demand, nutrient concentration, turbidity and a higher input of pathogens, leading to structural changes in the marine ecosystems and to a considerable hazard to public health. The percentage composition of phytoplankton standing crop between diatom and dinoflagellate was characterized by making a difference between the two groups in respect of location: a decrease of diatom and a increase of dinoflagellate in numerical abundance toward inner part from outer part of the bay. Namely phytoplankton organisms were composed of 80% of diatom and 20% of dinoflagellate in outer bay, on the contrary, only 4% of diatom and 96% of dinoflagellate occupied by 94% of prorocentrum micans known as tolerant species to polluted reaas in the inner bay. On the occurrence and composition of zooplankton, there are two significant communities in the bay:one is characterized by the predominance of Oithona nana and the other by Favella sp They were composed of a range from 84% to 90% of the total organisms and monotonously constituted of themselves only at most inner station 3 even small numbers. From the results mentioned above, Oithona nana, Favella and prorocentrum micans recommed themselves as valuable indicators for judging the extent of the marine pollution.During the period of the biossays Mytilus edulis showed the highest mortality and Tapes japonica the lowest one between the four test species. The highest death rate by stations was found at most inner stations 3'and 4near Masan Free Export Zone with the most sensitive response and the lowest one occured at outer station 13 where no death specimen of oyster and arkshell was found during the whole test period.As for mussel,85 percent death rate appeared after 72 hours and 100percent rate after 120hours at station 4. It was found that the significant high mortality of the test shellfish mentioned above was caused by severe pollution with mainly organic pollutants from domestic sewage and industrial wastes from the results of too much higher concentrations of dissolved inorganic nitrogen especially ammonia-N,COD,SS and lack of dissolved oxygen,and furthermore occurrence and abundance composition of Prorcentrum,Favella and Oithona nana by stations, valuable indicator species of coastal pollution by orgnic and boilogical pollutants.

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Studies on the N-Compounds during Chung-Kook-Jang Meju Fermentation -Amino acids of oligopeptides formed during Chung-Kook-Jang Fermentation- (청국장(淸國醬)메주 발효과정중(醱酵過程中)의 질소화합물(望素化合物)의 소장(消長)에 관(關)한 연구(硏究)(II) -저급(低級) peptide와 구성(構成)아미노산(酸)에 관(關)하여-)

  • Park, Ke-In
    • Applied Biological Chemistry
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    • v.15 no.2
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    • pp.111-142
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    • 1972
  • An experimental Chung-Kook-Jang was prepared using the strain Bacillus subtilis sp. isolated by the author Samples were taken in 12 hrs interval during the fermentation and the oligopeptides were separated by the method of molecular sieving using the ion exchange resin column of Dowex-50. Only the X-16 fraction of oligopeptides was taken and the components of oligopeptides were developed in two dimensional thin layer chromatograms. The each peptide spot was eluted and each peptide was isolated. The pattern and kinds of amino acids, and N and C-terminal amino acids were studied. Fourteen different oligopeptides could be detected by the two dimensional thin layer chromatography, all of which were consisted of $4{\sim}9$ kinds of amino acids. No dipeptides and no tripeptides could be found. The N and C-terminal amino acids and the residual component amino acids of all these 14 peptides could be summarized as the follows. [P]-I. Pro (Cys Ala Asp Trp Ile Val) Glu [P]-II. Val (His Arg Glu Thr Ala Met) Asp [P]-III. Glu (Cys Lys Asp Thr Met) Ala [P]-IV. Glu(His Ser Ala) Met) [P]-V. Ile (Cys Asp Arg Gly Pro T.p Phe) His [P]-VI. Gly(Asp ser) Lys [P]-VII. Thr(Pro Tyr Phe) Asp [P]-VIII. Phe(Tyr Leu Ile) Val [P]-IX. Trp (Phelle) Thr [P]-X. Ile (Arg Leu) Phe [P]-XI. Asp (Lys His Ser Gly Glu Pro) Ala [P]-XII. Glu (Cys Asp Gly) Ser [P]-XIII. Ala (Arg Tyr) Glu [P]-XIV. Met (Glu Ala) His It appears that the protease of the Bacillus subtilis K-27 syrain has rather wider range of specificity than proteases of Aspergoillus soya, pepsin, chymotrypsin, and trypsin.

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Seasonal Changes in Colonization and Spore Density of Arbuscular-Mycorrhizae in Citrus Groves (감귤뿌리에서의 Arbuscular-Mycorrhizae 형성과 감귤원 토양중 포자밀도의 계절적 변화)

  • Kim, Sang-Youb;Oh, Hyun-Woo;Moon, Doo-Khil;Han, Hae-Ryong;Chung, Jong-Bae
    • Korean Journal of Environmental Agriculture
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    • v.17 no.2
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    • pp.174-181
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    • 1998
  • In four citrus grow of Satsuma mandarin (rootstock of trifoliate orange) including two grove of organical management and two groves of conventional management, spores of arbuscular mycorrhizal(AM) fungi were identified and seasonal changes in spore density in soils and AM colonization of citrus roots were investigated. AM colonization in weeds found in the groves were also examined. Three species of Glomus (G.deserticola, G. vesiculiferum, G. rubiforme ) and one unknown species of Acaulospora were observed in all of the groves. Annual mean density of AM fungal spores were in the range of 10,000${\sim}$40,000 per 100g soil with more spores in the organically-managed groves. The least spores were observed in December in all groves, and the most spores in April in the organically-managed groves while in February or April in the conventionally- managed. Annual mean AM colonization more 27% of citrus root were observed in the organically-managed with the high peaks in April and October and the minimum in August, while mean colonization less than 15% in the conventionally-managed with the peak in February and the minimum in different times depending on groves and years. AM colonization corresponded to a sigmoidal curve consisting of a laf phase during winter and a subsequent increase in spring, then succeeded by a maximum, and then a decrease at the end of vegetation. Fungal spore density and AM colonization showed a parallel pattern during the sample period. The seasonality appeared to be related more to the phenology of the plant than to the soil factors. Generally more spore density and AM colonization were found in organically managed groves. AM colonization was not correlated with available P and organic matter content in soil in this field investigation. Among sixteen weed species found in the groves, Astrogalus sinicus of Leguminosae, Portulaca oleracea of Portulacaceae showed high colonization in all groves and they can be considered as a source of inoculumn and host plants for propagation of AM fungi.

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