抗生素FR-008基因簇上游区域的DNA序列分析     

陈实  周秀芬  JEONG Hae-Young  CHOI Kang-Ryul  LEE Sang-Yup  邓子新 《农业生物技术学报》2005,13(3):404-405

链霉菌FR-008产生一种七烯大环内酯类抗生素FR-008，对真菌具有很高的抗菌活性，并对蚊子幼虫有高毒性（袁德军和周启，1990）。负责合成FR-008的基因簇被定位（Hu et al．，1994），有21个基因（共138kb，GenBank accession number AY310323）被确认参与了抗生素FR-008的生物合成以及调节和外运（Chen et al．，2003）。然而，在FR-008基因簇最左端fscO基因上游的基因是否与FR-008抗生素生物合成相关？为此，本研究对FR-008基因簇上游区域进行了序列测定和分析。  相似文献   

Agglomeration and Competition among Chinese Cities: An Investigation of Taiwanese High‐Tech Foreign Direct Investment     

KENG‐HSIANG CHENG  YU‐CHING CHIAO  HSIN‐YU SHIH  TAI‐YU LEE  TA‐SHUN CHO 《Growth and change》2011,42(4):517-548

The purpose of this study was to investigate how Taiwanese high‐tech firms' foreign direct investment (FDI) leads to agglomeration and competition among cities in China. By using social network analysis to analyze 1,111 subsidiaries affiliated with 270 multinational corporations (MNCs) during the years between 1988 and 2006 in 30 major Chinese cities, this study finds that: 1) agglomeration in Chinese cities falls into three primary categories: the hub cluster, the communication‐extended cluster, and the computer‐extended cluster. Among the aforementioned clusters, the hub cluster is the most critical in terms of firm location, and therefore is often a high‐priority investment site for Taiwanese high‐tech firms. 2) Chinese cities fall into four primary groups, or “blocks”: the core block, the coast block, the inland block, and the periphery block; these groups were determined by applying a structural equivalence analysis of which members of each type are in competition with one another. By linking the findings of the urban network characteristics to Chinese regional economic policies, this study provides guidance to aid executives in determining the optimal location for future FDI. Implications and suggestions for host country governments in terms of firms' investment strategies are also discussed.  相似文献   

Role of myocardial catecholamines in cardiac contractility     

LEE WC  SHIDEMAN FE 《Science (New York, N.Y.)》1959,129(3354):967-968

In cats bilateral sympathectomy or administration of reserpine results in a marked reduction in concentration of myocardial catecholamines. The contractility of papillary muscles from such animals is significantly less than that of muscles from untreated animals. These findings demonstrate the importance of normal levels of myocardial catecholamines in the maintenance of normal cardiac contractility.  相似文献   

A low-resistance valve and indicating flowmeter for respiratory measurements     

SILVERMAN L  LEE RC 《Science (New York, N.Y.)》1946,103(2678):537-539

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Efficacy of probiotics from anaerobic microflora with prebiotics on growth performance and noxious gas emission in growing pigs     

Ho Sik JEONG  Sung Sill LEE 《Animal Science Journal》2011,82(2):282-290

We investigated the effect of probiotics from anaerobic microflora with prebiotics (synbiotics) on growth performance, noxious gas emission and fecal pathogenic bacteria populations in growing pigs. The basal diet, which contained approximately 25% corn, 24% whey, 12% wheat and 12% soybean meal, was supplemented alternatively with 0.15% antibiotics (US diet), prebiotics and 0.2% probiotics from anaerobic bacteria (BS diet), yeast (YS diet), mold (MS diet) or compounds (CS diet). One hundred and fifty pigs were fed an experimental diet for 15 days. Although the growth performance was not affected by supplemental synbiotics, the BS group showed higher dry matter and crude protein digestibility. The BS group decreased fecal ammonia and amine gas emissions, and increased fecal acetate gas emission compared with the US group. All synbiotics groups decreased in fecal propionate gas emission. Fecal Escherichia coli population was lower in the synbiotics groups than in the US group. Therefore, the results of the present study suggest that synbiotics exert similar effects with antibiotics on the nutrient digestibility and fecal microflora composition in growing pigs. Moreover, synbiotics can also decrease the fecal noxious gas emission in growing pigs.  相似文献   

Analysis of methanogenic archaeal communities of rumen fluid and rumen particles from Korean black goats     

Min‐Jung GU  Md. Jahangir ALAM  Seon‐Ho KIM  Che‐Ok JEON  Moon‐Baek CHANG  Young‐Kyoon OH  Sang‐Cheol LEE  Sang‐Suk LEE 《Animal Science Journal》2011,82(5):663-672

Molecular diversity of methanogens in the rumen of Korean black goats was investigated with 16S rRNA gene clone libraries using methanogen‐specific primers. The libraries were composed of rumen fluid‐associated methanogens (FAM) and rumen particle‐associated methanogens (PAM) from rumen‐fistulated Korean black goats. Among the 141 clones of the FAM library, the sequences were mostly related to two phyla, the Methanobacteriaceae family (77.3%) and the Thermoplasmatales family (22.7%); and among the 68 clones of the PAM library, sequences were also mainly clustered in the two phyla, the Thermoplasmatales family (63.24%) and the Methanobacteriaceae family (35.29%). Most of the sequenced clones in the two libraries were closely related to uncultured methanogenic archaeon. Quantitative real‐time PCR revealed that PAM (8.97 log 10) had significantly higher (P < 0.01) density of methanogens by the methanogenic 16S rRNA gene copies than FAM (7.57 log 10). The two clone libraries also showed difference in Shannon index (FAM library 1.70 and PAM library 1.59) and Chao 1 estimator (FAM library 18 and PAM library 17 operational taxonomic units). Apparent differences found in the microbial community from the two 16S rRNA gene libraries could be a result of such factors as the chemical and physical nature of the target material surface, types or component of diets, the interaction between the methanogens and other microbes, and age of the experimental goats.  相似文献   

IMAGING ASSESSMENT OF THE MODIFIED DOUBLE CONTRAST BARIUM ENEMA USING CARBOXYMETHYLCELLULOSE ON RADIOGRAPHY AND ULTRASONOGRAPHY IN DOGS     

MIHYUN CHOI  NAMSOON LEE  JUNYOUNG KIM  KANGJAE YI  JOOHYUN JUNG  JUNGHEE YOON  MINCHEOL CHOI 《Veterinary radiology & ultrasound》2011,52(6):648-652

A modified double contrast barium enema using carboxymethylcellulose was evaluated in beagle dogs and compared with dogs receiving a conventional barium enema. The experimental group was divided into three groups (1, 2, and 3) and given 30 ml/kg of different volume ratios of a barium vs. carboxymethylcellulose mixture. Each group underwent sonography following radiography. The volume ratio of one part barium to three parts carboxymethylcellulose was judged to be the optimal mixture, resulting in a general distribution of contrast and bowel radiolucency on radiographs and adequate postradiography sonography. The modified barium enema using carboxymethylcellulose is useful for assessing the general morphology and mucosal layers of the colon simultaneously on radiographs and ultrasonographs.  相似文献   

Generation of a Mixolab Profile After the Evaluation of the Functionality of Different Commercial Wheat Flours for Hot‐Press Tortilla Production     

Elieser S. Posner  Ana A. Chew‐Guevara  Marcelo Mitre‐Dieste  Esther Perez‐Carrillo  Erick Heredia‐Olea  Jeff D. Wilson  Sergio O. Serna‐Saldivar 《Cereal Chemistry》2014,91(2):139-145

Refined wheat flours commercially produced by five different U.S. and Mexican wheat blends intended for tortilla production were tested for quality and then processed into tortillas through the hot‐press forming procedure. Tortilla‐making qualities of the flour samples were evaluated during dough handling, hot pressing, baking, and the first five days on the shelf at room temperature. The predominant variables that affected the flour tortilla performance were wet gluten content, alveograph W (220–303) and P/L (0.70–0.94) parameters, farinograph water absorption (57%) and stability (10.8–18.7 min), starch damage (5.43–6.71%), and size distribution curves (uniform particle distribution). Flours produced from a blend of Dark Northern Spring (80%) and Mexican Rayon (20%) wheat had the highest water absorption, and tortillas obtained from this blend showed the highest diameter and lowest thickness. The whitest and best textured tortillas were obtained from the flour milled from three hard types of Mexican wheat blend. A Mixolab profile was generated from the best tortilla flours, those produced by mills 3 and 4. The Mixolab profile showed that a good flour for hot‐press tortillas had a relatively lower absorption and short dough mix time compared with a bread flour and should have a significantly higher gluten compared with an all‐purpose flour. Compared with bread flour, the tortilla flour had higher retrogradation and viscosity values. The Mixolab profile proved to be a good preliminary test to evaluate flours for hot‐press tortillas.  相似文献   

Discrimination and abundance estimation of wild and released abalone Haliotis diversicolor using stable carbon and oxygen isotope analysis in north-eastern Taiwan     

YING-CHOU  LEE  HUANG-HAUR  KUO  YUE-GAU  CHEN 《Fisheries Science》2002,68(5):1020-1028

The discrimination between wild and released Taiwan abalone Haliotis diversicolor was performed by stable carbon isotope analysis. Abalone samples were collected from Mao Aw Gulf in north-eastern Taiwan. Live abalone and dead shells were collected by divers with an 80 × 80 cm frame. The densities and amounts of wild and released abalone, as well as the survival rates of released abalone, in 1997 and 1998 were estimated. The age of the specimens was also determined from the specific temperature of each month and the inverse relationship between oxygen isotope values and temperatures. Results show that examining stable isotopic profiles proves to be a practical and feasible method for stock discrimination as well as density and abundance estimation. These data would be helpful in assessing the success of abalone culture and release programs, which aim to enhance this valuable marine resource.  相似文献   

Effect of sodium bicarbonate infusion on serum osmolality, electrolyte concentrations, and blood gas tensions in cats.   总被引：1，自引：0，他引：1  

D J Chew  M Leonard  W W Muir 《American journal of veterinary research》1991,52(1):12-17

The effects of single IV injections of sodium bicarbonate (0.5 mEq/kg of body weight, 1 mEq/kg, 2 mEq/kg, and 4 mEq/kg) on serum osmolality, serum sodium, chloride, and potassium concentrations, and venous blood gas tensions in 6 healthy cats were monitored for 180 minutes. Serum osmolality increased and remained significantly (P less than 0.05) increased for 120 minutes in cats given 4 mEq of sodium bicarbonate/kg. Serum sodium was increased significantly (P less than 0.05) for 30 minutes in cats given 4 mEq of sodium bicarbonate/kg. Serum sodium decreased and remained significantly (P less than 0.05) decreased for 120 minutes in cats given 1 g of 20% mannitol/kg, and serum osmolality was significantly (P less than 0.05) decreased at 30 and 60 minutes. Serum chloride decreased significantly (P less than 0.05) for 10 minutes in cats given 1 mEq of sodium bicarbonate/kg, and was significantly decreased for 30 minutes in cats given 2 mEq and 4 mEq of sodium bicarbonate/kg. Serum chloride decreased and remained significantly (P less than 0.05) decreased for 30 minutes in cats given 1 g of 20% mannitol/kg. Serum sodium and serum osmolality did not change significantly (P less than 0.05) in cats given 4 ml of 0.9% sodium chloride/kg. Serum potassium decreased significantly (P less than 0.05) for 10 minutes in cats given 1 mEq of sodium bicarbonate/kg, and for 120 minutes in cats given 2 mEq/kg or 4 mEq/kg. There was a significantly (P less than 0.05) greater decrease in serum potassium that lasted for 30 minutes after given sodium bicarbonate at the dosage of 4 mEq/kg, compared with other dosages given.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献