Tried and True Prokaryotes: Escherichia coli and Salmonella typhimurium     

Friesen JD 《Science (New York, N.Y.)》1988,240(4859):1678-1680

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Reaction of Ptr ToxA-Insensitive Wheat Mutants to Pyrenophora tritici-repentis Race 1     

Friesen TL  Rasmussen JB  Kwon CY  Francl LJ  Meinhardt SW 《Phytopathology》2002,92(1):38-42

ABSTRACT The host-selective toxin Ptr ToxA is produced by races 1 and 2 of Pyrenophora tritici-repentis, causal agent of tan spot of wheat. Ptr ToxA has been causally associated with pathogenicity by the race 2 phenotype in this system. However, the role of toxin in disease caused by race 1, the most prevalent form of the fungus in the central and northern Great Plains of North America, has not been rigorously investigated. Three independent wheat lines harboring mutations for insensitivity to Ptr ToxA were derived from ethylmethane sulfonate treatment of the hard red spring wheat cv. Kulm, possessing the single dominant gene for toxin sensitivity. Each of the three mutants was insensitive to Ptr ToxA in bioassays based on necrosis development and electrolyte leakage. Each mutant was crossed to each of the other mutants and to the wild-type Kulm. Segregation data indicate that each mutant line harbors a single recessive mutation for toxin insensitivity that maps to or near the same locus, possibly the toxin-sensitivity gene. Each toxin-insensitive mutant line was susceptible to two isolates of race 1 of P. tritici-repentis. F(2) and F(3) generations derived from crosses between Kulm and each mutant segregated for toxin reaction. However, segregation for fungal reaction was not evident, and all F(3) families were tan spot susceptible regardless of toxin reaction. Host insensitivity to Ptr ToxA is not necessarily equivalent to resistance to race 1. Ptr ToxA should not be used alone as a proxy for fungal inoculations by breeding programs aimed at developing tan spot-resistant wheat.  相似文献   

基于Pro/E的高度可调式人机学座椅设计     

沃宝安 《技术与市场》2010,(6):10-11

日常生活中随处可见的座椅给人们带来了很大的舒适性,但也出现了因长时间保持坐姿而产生的腰酸背痛情况。原因在于传统座椅的设计较少引入人体因素,因此,只有运用人机学原理设计的新型座椅才能解决这一问题。此外,诸如Pro/E之类的CAD软件也应该在现代设计中得到广泛应用,故本文尝试使用Pro/E建立模型。  相似文献   

Histological and ultrastructural appearance of severe Sarcocystis fayeri infection in a malnourished horse     

R J Cawthorn  M Clark  R Hudson  D Friesen 《Journal of veterinary diagnostic investigation》1990,2(4):342-345

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Pacific flows: The fluidity of remittances in the Cook Islands     

Evelyn Marsters  Nick Lewis  Wardlow Friesen 《Asia Pacific viewpoint》2006,47(1):31-44

Abstract: This paper contributes political and cultural‐economy perspectives to the critique of the MIRAB model 20 years on. In it, we celebrate the politically grounded reading by MIRAB analysts of development in the small island nations of the Pacific and their attention to both the empirical and the structural in their treatment of the economies of these countries. We address aspects, however, of one of the common critiques of MIRAB analyses: their failure to capture accurately the nature of small island socio‐cultural economies. We focus on the workings of remittance systems on two of the Cook Islands, Mauke and Manihiki, as the basis for a more thorough critique. We argue that rather than living economically and nationally determined lives, Cook Islanders live in rich networks of flows of goods, people, labour and meaning that the MIRAB model does not fully capture. The microeconomics of the transnational kin or household unit and the remittance decision are deeply embedded in such networks. These networks generate their own, temporary constellations of responsibility, economy and decision‐making, which may or may not materialise at any point as household economy. We consider some of the consequences of a network view for MIRAB analyses and for development in small island nations.  相似文献   

利用染色分析法确定农田土壤中硝态氮垂直运移的研究   总被引：1，自引：3，他引：1  

陈效民  吴华山  沃飞 《水土保持学报》2007,21(5):21-24

利用农田土壤剖面染色并结合田间硝态氮示踪的方法,研究了太湖地区典型的水稻土—白土剖面中优势流和硝态氮在土壤剖面中的运移规律。结果表明:染色法可以分析土壤剖面中大孔隙的分布状况和优势流的路径;染色面积越大的土层,表明该土层的大孔隙含量就越高。在白土剖面上,表层的大孔隙含量最高,20~30 cm和55~100 cm土层以下大孔隙含量都很低。在田间条件下,优势流是影响硝态氮迁移的主要因素;白土剖面中优势流直接影响的最大深度为78 cm,对地下水的影响很大。本试验中地下水的硝态氮含量比未试验前增加了10多倍,这对环境安全影响极大。  相似文献   

Factors affecting the dissolution and degradation of oriental mustard-derived sinigrin and allyl isothiocyanate in aqueous media   总被引：2，自引：0，他引：2  

Tsao R  Yu Q  Friesen I  Potter J  Chiba M 《Journal of agricultural and food chemistry》2000,48(5):1898-1902

Sinigrin, the predominant glucosinolate in the oriental mustard Brassica juncea, is mainly degraded upon the enzymatic action of myrosinase under normal conditions to give allyl isothiocyanate (AITC) in an aqueous media. Because AITC is considered to be the principal nematicidal ingredient in B. juncea, its stability in aqueous media is an important issue in achieving efficient nematode control. Pure sinigrin and AITC were found to be relatively stable in buffered water in the pH range of 5.00-7.00 but less stable at pH 9.00. Both sinigrin and AITC were more stable in soil water (supernatant of a 1:1 water/air-dried soil mixture) than in buffered water at the same pH range of 5.00-9.00. Sinigrin dissolved from the mustard bran or ground seed into water very quickly and was degraded by codissolved myrosinase to AITC. The AITC that formed from the degradation of sinigrin was found to be more stable in the soil water than in the buffered water. Buffer capacity was considered to be one of the factors that contributed to the stabilization of AITC in the soil water, but other unknown factors from both bran or seed and soil may also have contributed to the stabilization.  相似文献   

除草剂施田补对沼水蛙血细胞和心肌收缩能力的影响     

项君露  南旭阳  沃冬冬  王静静  沈江 《河南农业科学》2015,(4):149-153

以沼水蛙(Hylarana guentheri)为研究对象,研究了不同剂量的施田补溶液对沼水蛙的急性毒性效应及其外周血红细胞数/白细胞数、红细胞微核率、红细胞核异常率和总核异常率等的影响,同时利用Powerlab生物信号采集系统研究了施田补对沼水蛙心肌收缩能力的影响。结果显示,施田补对沼水蛙的96 h半致死剂量、安全剂量分别为1.149 9 m L/L和0.115 0 m L/L。所有药物组(0.012 5~0.400 0 m L/L)沼水蛙的血红细胞微核率、核异常率、总核异常率等均高于对照组,而且大部分药物组与清水对照组差异显著或极显著。在较高剂量(≥0.050 0 m L/L)中处理较长时间(192 h)时差异更加明显。所有药物组的外周血白细胞数/红细胞数与对照组相比差异均极显著。施田补对沼水蛙心肌收缩功能具有一定的毒害作用。综上,施田补对沼水蛙具有较大的毒害作用。  相似文献   

Effects of dietary lysine and energy density on performance and carcass characteristics of finishing pigs fed ractopamine   总被引：2，自引：0，他引：2  

Apple JK  Maxwell CV  Brown DC  Friesen KG  Musser RE  Johnson ZB  Armstrong TA 《Journal of animal science》2004,82(11):3277-3287

Two hundred sixteen crossbred barrows and gilts (84.3 kg BW) were used to test the effects of dietary energy density and lysine:energy ratio (Lys:ME) on the performance, carcass characteristics, and pork quality of finishing pigs fed 10 ppm ractopamine. Pigs were blocked by BW and gender, allotted to 36 pens (six pigs per pen), and pens were assigned randomly within blocks to dietary treatments (as-fed basis) arranged in a 2 x 3 factorial design, with two levels of energy (3.30 or 3.48 Mcal/kg) and three Lys:ME (1.7, 2.4, or 3.1 g lysine/Mcal) levels. Pigs were fed experimental diets for 28 d, and weights and feed disappearance were recorded weekly to calculate ADG, ADFI, and G:F. Upon completion of the feeding trial, pigs were slaughtered and carcass data were collected before fabrication. During carcass fabrication, hams were analyzed for lean composition using a ham electrical conductivity (TOBEC) unit, and loins were collected, vacuum-packaged, and boxed for pork quality data collection. Energy density had no (P > 0.22) effect on ADG or ADFI across the entire 28-d feeding trial; however, pigs fed 3.48 Mcal of ME were more (P < 0.02) efficient than pigs fed 3.30 Mcal of ME. In addition, ADG and G:F increased linearly (P < 0.01) as Lys:ME increased from 1.7 to 3.1 g/Mcal. Carcasses of pigs fed 3.48 Mcal of ME were fatter at the last lumbar vertebrae (P < 0.08) and 10th rib (P < 0.04), resulting in a lower (P < 0.03) predicted fat-free lean yield (FFLY). Conversely, 10th-rib fat thickness decreased linearly (P = 0.02), and LM depth (P < 0.01) and area (P < 0.01) increased linearly, with increasing Lys:ME. Moreover, FFLY (P < 0.01) and actual ham lean yield (P < 0.01) increased as Lys:ME increased in the diet. Dietary energy density had no (P > 0.19) effect on pork quality, and Lys:ME did not (P > 0.20) affect muscle pH, drip loss, color, and firmness scores. Marbling scores, as well as LM lipid content, decreased linearly (P < 0.01) as Lys:ME increased from 1.7 to 3.1 g/Mcal. There was a linear (P < 0.01) increase in shear force of cooked LM chops as Lys:ME increased in the finishing diet. Results indicate that 3.30 Mcal of ME/kg (as-fed basis) is sufficient for optimal performance and carcass leanness in pigs fed ractopamine. The Lys:ME for optimal performance and carcass composition seems higher than that currently used in the swine industry; however, feeding very high Lys:ME (> 3.0 g/Mcal, as-fed basis) to ractopamine-fed pigs may result in decreased marbling and cooked pork tenderness.  相似文献   

Effect of supplemental manganese on performance and carcass characteristics of growing-finishing swine     

Apple JK  Roberts WJ  Maxwell CV  Boger CB  Fakler TM  Friesen KG  Johnson ZB 《Journal of animal science》2004,82(11):3267-3276

Three hundred sixteen crossbred pigs were used in two experiments to determine the effect of supplemental manganese source and dietary inclusion level during the growing-finishing period on performance and pork carcass characteristics. All pigs were blocked by weight, and treatments were assigned randomly to pens within blocks. In Exp. 1, a total of 20 pens (five pigs/pen) was randomly assigned to one of five dietary treatments consisting of control grower and finisher diets, or control diets supplemented with either 350 or 700 ppm (as-fed basis) Mn either from MnSO4 or a Mn AA complex (MnAA). In Exp. 2, a total of 36 pens (six pigs per pen) was assigned randomly to one of six dietary treatments formulated with 0, 20, 40, 80, 160, or 320 ppm (as-fed basis) Mn from MnAA. Pigs were slaughtered when the lightest block averaged 120.0 kg (Exp. 1) or at a mean BW of 106.8 kg (Exp. 2). Neither ADG nor ADFI was affected (P > 0.21) by Mn source or high inclusion level (Exp. 1); however, across the entire feeding trial, pigs consuming 320 ppm Mn from MnAA were more (P < 0.04) efficient than pigs fed diets formulated with 20 to 160 ppm Mn from MnAA (Exp. 2). Color scores did not differ (P > 0.79) at the low inclusion (20 to 320 ppm Mn) levels used in Exp. 2; however, in Exp. 1, the LM from pigs fed Mn tended to receive higher (P = 0.10) American color scores than that of pigs fed the control diet, and Japanese color scores were higher for the LM from pigs fed diets containing 350 ppm Mn from MnAA than 350 Mn from ppm MnSO4 or 700 ppm Mn from MnAA (source x inclusion level; P = 0.04; Exp. 2). Chops of pigs fed 350 ppm Mn from MnAA were darker than the LM of pigs fed 350 ppm Mn from MnSO4, and 700 ppm Mn from MnAA diets (source x inclusion level; P = 0.03; Exp. 1), but L* values were not (P = 0.76) affected by lower MnAA inclusion levels (Exp. 2). Even though the LM tended to became redder as dietary MnAA inclusion level increased from 20 to 320 ppm Mn (linear effect; P < 0.10), a* values were not (P = 0.71) altered by including 350 or 700 ppm Mn (Exp. 1). Chops of pigs fed MnAA had lower cooking losses (P = 0.01) and shear force values (P = 0.07) after 2 d of aging than did chops from pigs fed diets formulated with MnSO4. Results from these experiments indicate that feeding 320 to 350 ppm Mn from MnAA during the growing-finishing period may enhance pork quality without adversely affecting pig performance or carcass composition.  相似文献