Atmospheric CO2 and climate on millennial time scales during the last glacial period     

Ahn J  Brook EJ 《Science (New York, N.Y.)》2008,322(5898):83-85

Reconstructions of ancient atmospheric carbon dioxide (CO2) variations help us better understand how the global carbon cycle and climate are linked. We compared CO2 variations on millennial time scales between 20,000 and 90,000 years ago with an Antarctic temperature proxy and records of abrupt climate change in the Northern Hemisphere. CO2 concentration and Antarctic temperature were positively correlated over millennial-scale climate cycles, implying a strong connection to Southern Ocean processes. Evidence from marine sediment proxies indicates that CO2 concentration rose most rapidly when North Atlantic Deep Water shoaled and stratification in the Southern Ocean was reduced. These increases in CO2 concentration occurred during stadial (cold) periods in the Northern Hemisphere, several thousand years before abrupt warming events in Greenland.  相似文献   

EGFR activation mediates inhibition of axon regeneration by myelin and chondroitin sulfate proteoglycans     

Koprivica V  Cho KS  Park JB  Yiu G  Atwal J  Gore B  Kim JA  Lin E  Tessier-Lavigne M  Chen DF  He Z 《Science (New York, N.Y.)》2005,310(5745):106-110

Inhibitory molecules associated with myelin and the glial scar limit axon regeneration in the adult central nervous system (CNS), but the underlying signaling mechanisms of regeneration inhibition are not fully understood. Here, we show that suppressing the kinase function of the epidermal growth factor receptor (EGFR) blocks the activities of both myelin inhibitors and chondroitin sulfate proteoglycans in inhibiting neurite outgrowth. In addition, regeneration inhibitors trigger the phosphorylation of EGFR in a calcium-dependent manner. Local administration of EGFR inhibitors promotes significant regeneration of injured optic nerve fibers, pointing to a promising therapeutic avenue for enhancing axon regeneration after CNS injury.  相似文献   

产黄青霉几丁质合成酶基因的克隆及系统学分析     

Nang.J Park.B.C 《安徽农业大学学报》1999,26(3):349-360

通过对产黄青霉基因组DNA进行PCR扩增得到几丁质合成酶基因的同源片段。经克隆及序列分析表明所得,片段为4种不同基因,分别命名为PcCHS1,PcCH-S2,PcCHS3及PcCHS4,经比较演绎氨基酸序列,PcCHS1属于I型几丁质合成酶,Pc-CHS2及PcCHS3为Ⅱ型,PcCHS4为Ⅲ型。为了进行产黄青霉的系统学研究,将几丁质合成酶基因保守区的演绎氨基酸片段进行同源性搜索及引导序列分析,结果表明青霉菌与子囊菌,尤其是曲霉属真菌具有紧密的演化关系。几丁质合成酶引导序列分析结果也支持了几丁质合成酶在丝状真菌系统学研究中的有效性。  相似文献   

Three-dimensional porous collagen/chitosan complex sponge for tissue engineering     

Sung Eun Kim  Yong Woo Cho  Eun Jung Kang  Ick Chan Kwon  Eunhee Bae Lee  Jung Hyun Kim  Hesson Chung  Seo Young Jeong 《Fibers and Polymers》2001,2(2):64-70

A three-dimensional, porous collagen/chitosan complex sponge was prepared to closely simulate basic extracellular matrix (ECM) constitutes, collagen and glycosaminoglycan. The complex sponge was prepared by a lyophilization method and had the regular network with highly porous structure, suitable for cell adhesion and growth. The pores were well interconnected, and their distribution was fairly homogeneous. The complex sponge was crosslinked using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) to increase its biological stability and enhance its mechanical properties. The crosslinking medium had a great effect on the inner structure of the sponge. The homogeneous, porous structure of the sponge was remarkably collapsed in an aqueous crosslinking medium. However, the morphology of the sponge remained almost intact in a water/ethanol mixture crosslinking milieu. Mechanical properties of the collagen/chitosan sponge were significantly enhanced by EDC-mediated crosslinking. The potential of the sponge as a scaffold for tissue engineering was investigated using a Chinese hamster ovary cell (CHO-K1) line.  相似文献   

UV-grafting coloration of cotton and wool fabrics using bismethacrylated quinizarin dye     

Yuanyuan?Dong  Laijiu?Zheng  Ju?Wei  Jinho?JangEmail author 《Fibers and Polymers》2016,17(10):1598-1604

A novel bifunctional quinizarin dye possessing two photoactive methacrylate groups was synthesized by the reaction of quinizarin with methacryloyl chloride. The synthesized dye, a low substantive dye under the conventional dyeing process, can be photografted onto cotton and wool fabrics at room temperature without neutral salts, which makes it a novel coloration process of excellent environmental friendliness. The concurrent polymerization and grafting of the synthesized dye onto cotton or wool can be assisted by a photoinitiator and acrylic acid in the case of cotton grafting. Moreover, color yields of the grafted fabrics improved significantly with the photografting of the bifunctional dye. The bifunctional dye can be photopolymerized with the increase in UV energy to 25 J/cm² and the oligomeric dye has a degree of polymerization of 5 or more. Furthermore, the color fastness properties of the grafted fabrics were superior to those of the dyed fabrics via exhaustion.  相似文献   

Dyeing and fastness properties of a reactive disperse dye on PET, nylon, silk and N/P fabrics     

Jin-Seok Bae  Jong Ho Park  Joonseok Koh  Sung Dong Kim 《Fibers and Polymers》2006,7(2):174-179

Dyeing and color fastness properties of a reactive disperse dye containing an acetoxyethylsulphone group on PET, Nylon, silk and N/P fabrics were examined. The reactive disperse dye exhibited almost the same dyeing properties on PET fabric as a conventional disperse dye except the level of dye uptake. The most appropriate pH and dyeing temperature for the dyeing of Nylon fabric were 7 and 100°C respectively. The build-up on Nylon fabric was good and various color fastnesses were good to excellent due to the formation of the covalent bond. Application of the reactive disperse dye on silk fabric at pH 9 and 80°C yielded optimum color strength. The rate of dyeing on Nylon fabric was faster than that on PET fabric when both fabrics were dyed simultaneously in a dye bath, accordingly color strength of the dyed Nylon was higher. The reactive disperse dye can be applied for one-step and one-bath dyeing of N/P mixture fabric with good color fastness.  相似文献   

Structural and biological study of carboxymethylated Phellinus linteus polysaccharides     

Shin JY  Lee S  Bae IY  Yoo SH  Lee HG 《Journal of agricultural and food chemistry》2007,55(9):3368-3372

Polysaccharides isolated from Phellinus linteus were chemically modified by carboxymethylation, and the structural and physiological properties of the derivative were investigated. 13C NMR spectroscopy showed that the polysaccharides extracted from P. linteus contained (1-3)-beta-glucans with a (1-6)-linkage. The carboxymetehylation of the P. linteus polysaccharides was confirmed by Fourier transform infrared spectroscopy, and the degree of substitution was obtained by the potentiometric titration, which was calculated to be 0.63. The bronchoalveolar lavage experiments showed that the carboxymethylated derivative raised the nitric oxide production. In addition, the carboxymethylation stimulated in vitro cytotoxic activity against the HT1080 cell line. Thus, the derivative exhibited the enhanced activity of immune systems, which would be explained by the improved water solubility and structural changes by carboxymethylation. However, a slight decrease in the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of the derivative was observed.  相似文献   

Cytoprotective effect of Panax ginseng on gallic acid-induced toxicity in TM3 mouse Leydig cells     

Park WH  Chang MS  Yang WM  Bae H  Kim NI  Park SK 《Fitoterapia》2007,78(7-8):577-579

Our previous study had demonstrated cytotoxicity of gallic acid on testicular cells with increasing the intracellular production of hydrogen peroxide. In the present study, the Panax ginseng root aqueous extract showed the cytoprotective effect on gallic acid-induced toxicity in TM3 mouse Leydig cells with decreasing the intracellular production of hydrogen peroxide.  相似文献   

Growth performance and color enhancement of goldfish,Carassius auratus,fed diets containing natural dyes extracted from annatto (Bixa orellana) seeds     

S.H.S Dananjaya  Prabuddha Manjula  A. S. Dissanayake  M. Edussuriya  K. Radampola  Bae Keun Park 《Journal Of Applied Aquaculture》2020,32(1):53-69

ABSTRACT

The present study was conducted to evaluate growth performance and color enhancement of goldfish, Carassius auratus, fed diets containing 0, 50, 100, 200, and 250 mg kg^?1 diet of annatto dye (AD) for 60 days. The survival rate was significantly higher in fish fed 100, 200, and 250 mg AD kg^?1 diet over than these fed control and 50 mg AD kg^?1 diet (p < 0.05). AD significantly (p <0 .05) increased the pigmentation in the skin and caudal fin of goldfish in a concentration dependent manner (R² = 0.995, 0.997). The highest amount of total carotenoid deposition in fish skin and fins were given by diets containing 200–250 mg AD kg^?1 diet. The highest redness (a*) of 43.21 and yellowness (b*) of 12.53 were obtained by 250 and 50 mg AD kg^?1, respectively. The present results show that AD can be successfully used as an alternative natural carotenoid source in goldfish diets at levels of 200–250 mg AD kg^?1 diet.  相似文献   

Dietary lipid requirement of whiteleg shrimp Litopenaeus vannamei juveniles cultured in biofloc system     

Ali Hamidoghli  Seonghun Won  Frolan A. Aya  Hyeonho Yun  Jinho Bae  In‐Kwon Jang  Sungchul C. Bai 《Aquaculture Nutrition》2020,26(3):603-612

An eight‐week feeding trial was conducted to evaluate the contribution of biofloc on dietary lipid requirement in whiteleg shrimp Litopenaeus vannamei. Five diets with graded levels of dietary lipid (45, 60, 90, 120 and 150 g/kg) were fed to juvenile shrimp. Final weight, weight gain and specific growth rate of shrimp fed diets with 60, 90 and 120 g/kg lipid levels were significantly higher than those of shrimp fed diets with lipid levels 45 and 150 g/kg (p < .05). Feed efficiency and protein efficiency ratio of shrimp fed 60, 90 and 120 g/kg were higher than those fed 150 g/kg diet. Plasma total cholesterol and triglyceride levels were lower in shrimp fed 45 g/kg compared with those fed the 90 g/kg (p < .05). Also, lysozyme activity for 90 g/kg group was higher than the 15 g/kg group. Hepatopancreas lipase and amylase activities of shrimp fed 90 and 120 g/kg diets were significantly higher than those of shrimp fed 45 and 150 g/kg diets. Broken‐line regression analysis for weight gain indicated that the dietary lipid requirement of whiteleg shrimp juveniles reared in a biofloc system was estimated to be higher than 56 g/kg but <60 g/kg.  相似文献