Effect of Non-animal-Derived Nitrogen Sources on the Production of Hyaluronic Acid by Streptococcus sp. KL0188

Lee, Gil-Yong,Ha, Suk-Jin,Jung, Jong-Hyun,Seo, Dong-Ho,Park, Jong-Yul,Kim, Su-Rin,Park, Nam-Woo,Kweon, Dong-Keon,Park, Sang-Hoo,Park, Cheon-Seok The Korean Society for Applied Biological Chemistr 2009 Applied Biological Chemistry (Appl Biol Chem) Vol.52 No.3

Hyaluronic acid (HA) is a linear high-molecular-weight polysaccharide with useful biomedical applications. Streptococcus zooepidemicus, a typical HA-producing bacterium, requires an animal-derived nitrogen source such as tryptone, peptone or sheep blood as a nutrient. Sixteen non-animal-derived (NAD) nitrogen sources were tested as a replacement for the expensive animal-derived nitrogen sources, which may have safety issues. Among the sixteen tested NAD nitrogen sources, a yeast-derived nitrogen source (YE 0251) showed the highest HA productivity, which was equivalent to the control HA production medium containing tryptone in a 5-L jar and in 3,000-L industrial fermentations. In the 3,000-L fermentation, YE 0251 increased cell mass (dry cell weight) and HA production by 11% and 8%, respectively, compared with the control HA production medium. The fmal specific volumetric productivity (0.41 g/L h) was improved by about 70% after reducing the fermentation time from 20 h to 12 h, compared to the conventional production medium.

갈대 생육지에서 질소 시비가 사초의 생육과 수량 및 사료가치에 미치는 영향

서성,박진길,김원호,김맹중,이상학,정종성,박형수,성하균,이종경,Seo, Sung,Park, Jin Gil,Kim, Won Ho,Kim, Meing Jooung,Lee, Sang Hak,Jung, Jong Sung,Park, Hyung Soo,Sung, Ha Guyn,Lee, Joung Kyong 한국초지조사료학회 2013 한국초지조사료학회지 Vol.33 No.2

본 연구는 질소(N) 시비가 부존 조사료자원인 갈대(Phragmites communis)의 생육과 수량 및 사료가치에 미치는 영향을 구명하고자 2012년에 충남 천안과 경기 안산지역에서 실시되었다. 천안 국립축산과학원 갈대 재배지에서는 N 무시비구, N 50 kg/ha구, N 100 kg구 등 3처리를 두고 4월 30일 시비, 6월 21일 수확하였으며, 안산 시화간척지 갈대 자생지에서는 N 무시비구, N 60 kg/ha구 등 2처리를 두고 5월 1일 시비, 8월 1일 수확하였다. 갈대의 초장과 엽색은 N 시비구에서, 그리고 N 시비수준이 높을 때 양호하였다. 건물률은 N 시비구에서 약간 낮아지는 경향으로 천안지역은 무시비구 39.8%, N 시비구 37.6%, 36.7%, 안산지역은 무시비구 39.4%, N 시비구 37.6%였다. 천안지역의 건물수량, 조단백질 수량 및 가소화 건물수량은 무시비구에서 ha당 각각 4,026 kg, 235 kg, 1,850 kg, N 50 kg 시비구는 각각 4,658 kg, 306 kg, 2,388 kg, N 100 kg 시비구는 각각 5,622 kg, 446 kg, 3,143 kg으로 유의적으로 증가하였으며 (p<0.05), 안산지역은 무시비구에서 각각 2,802 kg, 177 kg, 1,288 kg, N 60 kg 시비구는 각각 3,876 kg, 294 kg, 1,853 kg으로 유의적으로 증가하였다 (p<0.05). 천안지역의 조단백질 함량, 건물 소화율 및 상대사료가치 (RFV)는 무시비구에서 각각 5.85%, 45.96%, 64.0 (품질 5등급), N 50 kg 시비구는 각각 6.58%, 51.27%, 72.3 (5등급), N 100 kg 시비구는 각각 7.94%, 55.91%, 72.7 (5등급)로 높아졌으며, 안산지역도 무시비구에서 각각 6.30%, 45.98%, 70.2 (5등급), N 60 kg 시비구는 각각 7.59%, 47.80%, 78.3 (4등급)으로 높아지는 경향이었다. 이상의 결과를 종합하여 볼 때, 갈대 생육지는 시비가 가능한 조건이라면(하천변이나 강변 등 수질오염이 우려되는 지역이 아닌), ha당 N 60~100 kg을 생육기에 시용해 주는 것이 생산량과 사료가치를 크게 개선시켜줄 수 있어 바람직하였다. This study was carried out to investigate the effect of nitrogen (N) fertilization on the forage growth, production and quality of native reed (Phragmites communis) grasses. Field experiments were conducted in Cheonan and in Ansan, 2012. Treatments were control (no N fertilization), 50 kg/ha and 100 kg/ha in Cheonan plots (fertilization on April $30^{th}$, and harvest on June $21^{st}$). Treatments in Ansan plots were control (no N fertilization) and 60 kg/ha (fertilization on May first, and harvest on August first). Forage growth and leaf colors were improved in N fertilized plots. However, the drymatter (DM) percentage was slightly decreased with N fertilization. Forage yields, in terms of DM, crude protein (CP) and digestible DM (DDM), were significantly increased with N fertilization in both sites. In Cheonan, DM, CP and DDM yields per ha were 4,026 kg, 235 kg and 1,850 kg, respectively, in the control plot, and were 4,658 kg, 306 kg and 2,388 kg, respectively, in the N 50 kg plot, and 5,622 kg, 446 kg and 3,143 kg, respectively, in the N 100 kg plot. In Ansan, DM, CP and DDM yields per ha were 2,802 kg, 177 kg and 1,288 kg, respectively, in the control plot, and were 3,876 kg, 294 kg and 1,853 kg, respectively, in the N 60 kg plot. Forage quality in terms of CP content, in vitro DM digestibility (IVDMD) and relative feed value (RFV) were also increased with N fertilization in both sites. In Cheonan, the CP content, IVDMD and RFV were 5.85%, 45.96% and 64.5 (grade 5), respectively, in the control plot, 6.58%, 51.27% and 72.3 (grade 5), respectively, in the N 50 kg plot, and 7.94%, 55.91% and 72.7 (grade 5), respectively, in the N 100 kg plot. In Ansan, the CP content, IVDMD and RFV were 6.30%, 45.98% and 70.2 (grade 5), respectively, in the control plot, and 7.59%, 47.80% and 78.3 (grade 4), respectively, in the N 60 kg plot. In conclusion, N fertilization of 60~100 kg/ha was desirable for greater forage production, with a higher quality of native Phragmites communis achievable. This should only be applied if the fertilization area is not located at a riverside/streamside or in riparian land where there is a high risk of water pollution by fertilization.

Nanohybrid magnetic liposome functionalized with hyaluronic acid for enhanced cellular uptake and near-infrared-triggered drug release

Nguyen, Van Du,Zheng, Shaohui,Han, Jiwon,Le, Viet Ha,Park, Jong-Oh,Park, Sukho Elsevier 2017 Colloids and surfaces Biointerfaces Vol.154 No.-

<P><B>Abstract</B></P> <P>The aim of this work is to prepare and evaluate a novel lipid-polymer hybrid liposomal nanoplatform (hyaluronic acid-magnetic nanoparticle-liposomes, HA-MNP-LPs) as a vehicle for targeted delivery and triggered release of an anticancer drug (docetaxel, DTX) in human breast cancer cells. We first synthesize an amphiphilic hyaluronic acid hexadecylamine polymer (HA-C<SUB>16</SUB>) to enhance the targeting ability of the hybrid liposome. Next, HA-MNP-LPs are constructed to achieve an average size of 189.93±2.74nm in diameter. In addition, citric acid-coated magnetic nanoparticles (MNPs) are prepared and embedded in the aqueous cores while DTX is encapsulated in the hydrophobic bilayers of the liposomes. Experiments with coumarin 6 loaded hybrid liposomes (C6/HA-MNP-LPs) show that the hybrid liposomes have superior cellular uptake in comparison with the conventional non-targeting liposomes (C6/MNP-LPs), and the result is further confirmed by Prussian blue staining. Under near-infrared laser irradiation (NIR, 808nm), the HA-MNP-LPs aqueous solution can reach 46.7°C in 10min, and the hybrid liposomes released over 20% more drug than the non-irradiated liposomes. Using a combination of photothermal irradiation and chemotherapy, the DTX-loaded hybrid liposomes (DTX/HA-MNP-LPs) significantly enhance therapeutic efficacy, with the IC<SUB>50</SUB> value of 0.69±0.10μg/mL, which is much lower than the values for DTX monotherapy. Consequently, the prepared hybrid nanoplatform may offer a promising drug delivery vehicle with selective targeting and enhanced drug release in treating CD44-overexpressing cancers.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel polymer-lipid nanohybrid liposomes for active tumor targeting are synthesized. </LI> <LI> Magnetic nanoparticles and drug are encapsulated for photothermal-chemotherapy. </LI> <LI> Nanohybrid liposomes significantly enhance cellular uptake to breast cancer cells. </LI> <LI> Near-infrared light can trigger drug release from the nanohybrid liposomes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

차량 재도색용 청색 페인트의 분석

박성우,손성건,박하선,박성지,정영호,홍성욱,박종신 內務部 國立科學搜査硏究所 2002 國立 科學 搜査 硏究所 年報 Vol.34 No.-

Distribution of the Fairy Pitta (Pitta nympha) in the South Korea: A focus on protected areas

Gil-Pyo Hong(홍길표),Jae-Hoon Kim(김재훈),Seul-Gi Seo(서슬기),So-Yeon Cho(조소연),Bo-Yeon Hwang(황보연),Jong-Hyun Park(박종현),Seung-Yeon Lee(이승연),Ga-Young Kim(김가영),Wan-Hee Nam(남완희),Ha-Cheol Sung(성하철) 한국조류학회 2021 한국조류학회지 Vol.28 No.2

국내 팔색조(Pitta nympha) 분포 현황을 알아보고자 전국 국립공원 등 보호지역 중심으로 총 19개 지역을 조사하였고, 전문가 네트워크를 통해 자료를 보강하였다. 전국 19개 지역을 조사한 결과 북한산, 지리산 등 내륙지역 7개 국립공원에서는 팔색조가 확인되지 않았고, 경남 거제, 남해, 해남, 장흥 고흥 등 남해안과 인접한 12개 지역에서 팔색조 서식이 확인되었다. 또한 전문가 네트워크를 통해 수집한 팔색조 출현 위치 정보 82건을 분석한 결과, 전국 8개 광역지자체 모두 팔색조 서식이 확인되었고, 내륙지역(26.8%)보다 해안지역(73.2%)에서 더 많이 출현하였다. 연구 결과를 종합해보면, 우리나라의 팔색조는 주로 제주도와 남해안 지역을 중심으로 많이 분포하며, 그 보다 적은 개체수가 내륙 지역에 넓게 분포하고 있는 것으로 나타났다. The present study investigated the current distribution of Fairy Pitta (Pitta nympha) in South Korea. A total of 19 study areas, including protected areas such as national and provincial parks in South Korea were surveyed, and additional data obtained from an expert network. According to the results, Fairy Pitta was absent in seven inland national parks, including Mt. Bukhan and Chiri parks. Fairy Pitta inhabited 12 areas near the southern coast of South Korea, including Geoje, Namhae, Haenam, Jangheung, Goheung, and Gyeongnam Province. The analysis results of 82 datasets obtained from experts with regard to the locations where Fairy Pitta have been spotted showed that the bird inhabits all the eight metropolitan regions in South Korea, and is more frequently spotted in coastal areas (73.2%) than in inland areas (26.8%). The findings demonstrate that Fairy Pitta is mainly distributed in Jeju Island and the southern coast of South Korea, and is distributed in inland areas at relatively lower numbers.

ACCase 저해 제초제 cyhalofop-butyl에 대한 경남지방 수집종 피의 저항성

원종찬,원옥재,하준,임일빈,강광식,변종영,박기웅,이증주,Won, Jong Chan,Won, Ok Jae,Ha, Jun,Im, Il-Bin,Kang, Kwang Sik,Pyon, Jong Yeong,Park, Kee Woong,Lee, Jeung Joo 한국잡초학회한국잔디학회 2018 Weed & Turfgrass Science Vol.7 No.2

Repeated use of ACCase inhibiting herbicides for a long time has resulted in increases of resistant Echinochloa oryzicola populations in paddy fields in middle west area of Korea. This study aims to investigate current status of herbicide resistant E. oryzicola in Gyeongsangnam-do, in which there is less information about herbicide resistance. For resistance frequency and dose-response study, seeds from 100 individual plants of E. oryzicola in Gyeongsangnam-do were collected and tested with cyhalofop-butyl. Seven percent of plants from Gyeongsangnam-do was resistant at a recommended rate of cyhalofop-butyl. $GR_{50}$ values (herbicide rates required to reduce plant growth 50%) for one representative resistant populations and five susceptible populations were $738g\;a.i.\;ha^{-1}$ and 66-234 (average 147)$g\;a.i.\;ha^{-1}$, respectively, indicating average 5 times difference in resistance. Although lower rate of frequency of herbicide resistance in Gyeongsangnam-do than in Jeollabuk-do, increases of herbicide resistance are expected in this area because of increases of direct seeded rice fields and increases of dependence on a specific herbicide. Therefore, it is necessary to monitor herbicide resistance regularly and conduct integrated herbicide resistance management in this area. 경남지역 제초제 저항성 피의 발생현황과 저항성 정도를 알아보기 위하여 벼 재배 논에서 100개체의 피 종자를 수집하여 ACCase 저해제인 cyhalofop-butyl에 대한 약량반응 실험을 수행한 결과, 수집한 피의 7%가 저항성으로 조사되었다. 선발된 감수성 5개체의 $GR_{50}$값은 평균 $147g\;a.i.\;ha^{-1}$로 나타났고, 함양 지역의 저항성 개체의 $GR_{50}$값은 $738g\;a.i.\;ha^{-1}$ 로 R/S (ratio of resistance to sensitivity)값은 5.01배로 나타났다. 현재 경남지역에서의 저항성 피의 발생 수준은 낮은 것으로 나타났지만, 저항성 피의 확산을 지연시키거나 막기 위해서는 주기적인 저항성 피의 모니터링과 체계적인 저항성 잡초 관리방안을 마련하여 수행할 필요가 있다.

김치유래 젖산균의 균체지방산 분석을 이용한 분류학적 연구

이정숙,정민철,김우식,이근철,김홍중,박찬선,이헌주,주윤정,이근종,안종석,박완,박용하,민태익 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 1996 한국미생물·생명공학회지 Vol.24 No.2

표준균주를 포함한 230여개의 김치유래 젖산균에 대한 균체지방산(FAMEs)을 분석하였다. FAMEs profiles는 Euclidian Distance 17.5에 의해 7개의 Major Cluster와 1개의 Single Cluster로 나뉘어졌다. 이중 A, B, C 및 Cluster는 Leuconostoc속으로 분석되어졌고, F는 Lactobacillus속으로 분석되어졌다. 그리고 E와 G cluster는 두개의 Genus가 혼재되어 나타났으며 보충적인 연구가 필요하다. 앞으로 김치유래 젖산균의 균체지방산 분석결과를 기반으로 한 데이타베이스에 95가지 탄소원을 이용하는 수치분류학적 접근방법 및 Pyrolysis Mass Spectrometry 등의 화학적 분석 방법과 분자친화적 연구를 통한 종합적 분류정보 체계가 갖추어지면 젖산균의 신속, 정확한 동정 및 연구에 활발히 이용되어질 것이다. Two hundreds and thirty lactic acid bacteria, mostly isolated from Kimchi, including type strains were sued for analysis of cellular fatty acids. The 230 test strains were recoverd in 7 major and 1 single clusters defined a Euclidian distance of 17.5. These aggregate taxa were equivalent to the genus Leuconostoc (aggregate group A, B, C and D), and the genera Leuconostoc and Lactobacillus (aggregate group G). It is concluded as evident that FAMEs (Fatty Acid Methyl Esters) profile of cell can be used as a criterion in classification of lactic acid bacterial from kimchi. Additional comparative taxonomic studies need to be carried out on well chosen representative strains to determine the most appropriate methods of value.

2010 파주, 안산지역 갈대, 억새 등 야초류의 이용실태와 사료가치 평가

서성(Sung Seo),김원호(Won Ho Kim),정민웅(Min Woong Jung),박형수(Hyung Soo Park),심재진(Jae Jin Shim),박진길(Jin Gil Park),성하균(Ha Guyn Sung),김종덕(Jong Duk Kim),이종경(Joung Kyong Lee) 한국초지조사료학회 2011 한국초지조사료학회지 Vol.31 No.2

본 연구는 부존 조사료자원의 이용을 활성화하여 수입사료를 줄이고 가축 사료비를 절감하고자 2010년도에 경기 파주 (민통선 지역)와 경기 안산 (시화지구)에서 갈대와 억새 등 야초자생지를 탐색하고, 수확?이용실태 조사와 함께 사료가치를 분석하였다. 파주 민통선 내억새 (Miscanthus sinensis)와 갈대 (Phragmites communis) 혼합 자생지는 90~100 ㏊ 규모로, 1차 곤포작업으로 사일리지 520톤 (㏊당 6톤), 2차로 380톤 (㏊당 4톤)을 조제하여, 연 사일리지 900톤 (㏊당 10톤)을 생산하였다. 곤포의 유통가격은 롤당 52~55천 원으로 ㎏당 130~137.5원이었다. 곤포는 자가소비 50~70%, 판매유통 30~50%로, 수익성은 인건비 정도로 추정되었다. 초장 70 ㎝의 재생 억새는 조단백질 9.6%, 상대사료가치 82.4 (건초 4등급), 건물 소화율 67.7%, 초장 70 ㎝의 재생 갈대는 각각 13.8%, 84.3 (4등급), 67.9%로 사료가치는 높았으며, 수확이 늦어짐에 따라 사료가치는 크게 낮아졌다. 안산 시화지구 (3공구)의 갈대 등 야초류자생지는 100 ㏊ 정도로 2009년도에는 50 ㏊에서 사일리지 550톤 (㏊당 11톤)을 생산하여 롤당 50천 원에 유통하였으며, 2010년도는 잦은 강우와 장마로 부분 이용에 그쳤다. 고초기의 갈대는 건물률 89.8%, 조단백질 2.2%, NDF 80.6%, ADF 55.4%, 상대사료가치 52.9 (5등급), 건물 소화율 36.4%로 볏짚에 비해서도 사료가치는 크게 낮았다. 초장 80 ㎝의 재생 갈대는 조단백질 12.9%, 상대사료가치 99.8 (3등급), 건물 소화율 66.6%로 사료가치는 양호하였으며, 개화기의 초장 150 ㎝ 갈대는 조단백질 4.5%, 상대사료가치 59.9 (5등급), 건물 소화율 42.2%로 볏짚의 사료가치와 비슷하였다. 이상의 결과를 종합하여볼 때, 갈대, 억새 등 야초류는 현 상태에서 최대한 수거?이용하되, 사료가치를 유지하고 가축 기호성을 고려한 시기에 수확하는 것이 중요하며, 최소한 볏짚과 비슷하거나 그 이상의 사료가치를 기대하기 위해서는 7월 중순 이전 (늦어도 7월까지)에 수확?이용하는 것이 권장된다. 본 연구에서 조사된 대부분의 야초류는 상대사료가치가 75 이하인 건초 5등급으로 사료가치는 매우 낮았으며, 키가 작은 영양생장기에 수확한 경우에만 4등급으로 나타났다. 부존 조사료자원의 이용은 양질의 사료작물 생산과 병행하여 추진하는 것이 바람직하였다. This study was carried out in 2010 to investigate the utilization and nutritive value of native grasses, such as Phragmites communis and Miscanthus sinensis which might reduce the cost of feeding domestic cattle. The regions within the Civilian Control Line in Paju and Sihwa region in Ansan were surveyed. In Paju, the yearly silage production was 900 MT harvested from 90 ha (10 MT/㏊). About 30~50% of these were sold out at the marketing price of 52,000~55,000 Won per roll (130~137.5 Won/㎏). Regrown Miscanthus sinensis of 70 ㎝ in length contained 9.6% of crude protein (CP), 82.4 of relative feed value (RFV), and 67.7% of in vitro dry matter digestibility (IVDMD). Regrown Phragmites communis of 70 ㎝ in length contained 13.8% of CP, 84.3 of RFV, and 67.9% of IVDMD. As harvesting was delayed, the quality was decreased dramatically. In Ansan region, Phragmites communis plantation covers 100 ha. The silage production was 550 MT from the area of 50 ha (11 MT/㏊) in 2009. And the marketing price was 50,000 Won per roll. But in 2010 only a small amount of grasses could have been baled due to frequent and much rainfall from spring to summer season. However, the good forage quality was observed from regrown Phragmites communis of 80 ㎝ in length, 12.9% CP, 99.8 RFV and 66.6% IVDMD, while that of late matured grasses was very low, 2.2% CP, 52.9 RFV and 36.4% IVDMD, greatly lower than forage quality of rice straw. The quality of grasses at bloom stage of 150 ㎝ in length was similar to that of rice straw, showing 4.5% CP, 59.9 RFV and 42.2% IVDMD. In conclusion, the overall quality of most native grasses in this survey were very poor. Therefore, we recommend that Phragmites communis and Miscanthus sinensis should be harvested during June or July to obtain better forage quality which is richer in forage values than rice straw. Production of high quality forage crops was also desirable for self sufficiency of forage.

연안 도시 대기오염 물질의 농도분포 특성

박종길,석경하,김지형,차주완 한국환경과학회 2002 한국환경과학회지 Vol.11 No.12

This paper aims to find the characteristics of concentration distribution of coastal urban air pollutants. For this purpose, It was used the daily meteorological data and hourly concentration data O_3 and NO_2 in Busan metropolitan city from 1994 to 1996. It was investigated the annual and monthly distribution of ozone and nitrogen dioxide concentration at each site in Busan, and also investigated the characteristics of concentration change of air pollutants with time under the sea breeze. As a results, the concentration of nitrogen dioxide and ozone tend to be increased every year and nitrogen dioxide concentration is higher than ozone concentration at all site in Busan. The concentration of ozone is high in summer season and low in winter season, but the concentration of nitrogen dioxide have a reversed trend. The monthly peak concentration of ozone occurred in April and September, while the monthly minimum concentration of nitrogen dioxide occurred in August. Their trend were indentified by sites near the coastline than sites stands apart from the coastline. The sea breeze occurred annual mean 81 days in Busan from 1994 to 1996. The main wind direction of sea breeze was classified into southeasterly. In case of southwesterly, It was pronounced the south wind and southwest wind. In case of southeasterly, the occurrence frequency of east wind was high. Especially, the concentration of urban air pollutants, such as ozone and nitrogen dioxide, were high on time which the sea breeze flow, and the areas that ozone concentration was high moved from outside part to central part of city with time. In costal urban such as Busan, the wind direction of sea breeze is influenced the influenced the change of ozone and nitrogen dioxide concentration on time which the sea breeze flow at each site and air pollutants concentration of sites on the pathway of sea breeze.

정상 인체 멜라닌세포에서 endothelin-1 receptor antagonist가 melanin생성에 미치는 영향에 관한 연구

박진우,이종석,황규왕,김정하 순천향의학연구소;Soonchunhyang Medical Research Institute 2000 Journal of Soonchunhyang Medical Science Vol.6 No.1

In the normal skin, melanocytes maintain their constant population and their melanogenic activity in steady state, but respond to several stimulus such as UV radiation and chemical irritation, to accentuate proliferation and differentiation, leading to hyperpigmentation of the skin. Human Keratinocytes produce and secrete endothelin-1, which can be strong mitogens for human melanocytes. The paracrine linkage of endothelin-1 between keratinocytes and melanocytes suggested that endothelin-1 is intrinsic mediators for human melanocytes in UVB-induced pigmentation. The purpose of this study is to investigate the new whitening agent, which improve the hyperpigmentation by inhibiting the ET-1. So, we add ET-1 and five kinds of ETRA into the cultured normal human melanocyte and then three days later, each ETRA on ET-1 was measured melanocyte number and inhibitory effect of melanin synthesis, respectively. In this study, ETRA has a inhibitory effect on ET-1 induced melanocyte proliferation and melanogenesis. ETRA I has a strong inhibitory effect on melanocyte proliferation and ETRA Ⅱ has a strong inhibitory effect melanogenesis. western blotting results shows negative. It may be due to the processing error of protein denaturing or low antigen -antibody affinity. But, we also confirm that ETRA Ⅱ has a inhibitory effect of tyrosinae synthesis by RT-PCR