鹅大肠埃希菌的分离鉴定及系统进化树分析     

张备  金振华  孙金艳  李烨  王丽坤  鹿凌岩  史同瑞 《中国畜牧兽医》2021,48(3):1020-1026

为对发病鹅感染致病性大肠埃希菌的临床治疗提供指导并防控致病性大肠埃希菌感染,本研究无菌采集腹泻鹅及病死鹅脾脏、肝脏等组织器官进行病原菌分离培养、染色观察、生化鉴定、致病性试验,对菌株部分基因进行测序、构建遗传进化树并进行药敏试验。结果显示,普通琼脂培养基上生长出灰白色、圆形、凸起、边缘整齐菌落,麦康凯琼脂培养基上长出玫红色、光滑圆润菌落;分离菌株经革兰氏染色,镜下可见革兰氏阴性菌,两端钝圆、大小中等,多呈单个存在的杆状菌;致病性试验表明,该分离菌株对小鼠、雏鹅均有较高致死率;遗传进化树结果显示,分离菌株与患者粪便分离株（GenBank登录号：CP024992.1）同源性最高,达99.5%;体外抑菌试验发现菌株耐药情况较严重,对大多数抗菌药均有较强抗性,仅头孢噻呋对该分离株有较强的抑菌作用,合理用药后病情得到有效控制。本研究为有效防治鹅大肠埃希菌病提供了理论依据,对规模化鹅场防控大肠埃希菌等其他细菌性疾病具有重要价值。  相似文献   

电车接触网腕臂的计算     

李艾 《湖南农机》2015,(4)

电气化铁道的“三大元件”分为接触网、电力机车和牵引变电所。本论文论述时速200Km/h高速电气化铁路的接触网电车接触网腕臂的计算,接触网的计算精确程度就关系到接触线悬挂的可靠程度,故接触网计算是设计中基础的工作内容,其计算主要分为腕臂的计算和接触网的负载计算。文章详细分析了腕臂长度的计算方法,重点介绍了路基曲线区段腕臂长度、转换柱和中心柱腕臂长度的计算。  相似文献   

Canine fetal echocardiography: correlations for the analysis of cardiac dimensions     

Amália Turner Giannico  Elaine Mayumi Ueno Gil  Daniela Aparecida Ayres Garcia  Marlos Gonçalves Sousa  Tilde Rodrigues Froes 《Veterinary research communications》2016,40(1):11-19

The aim of this study was to develop regression models for correlation of canine fetal heart development with body size to characterize normal development or suggest cardiac anomalies. Twenty clinically healthy pregnant bitches, either brachycephalic and non-brachycephalic, were examined ultrasonographically. Transabdominal fetal echocardiography was conducted every 4 days from the beginning of cardiac chambers differentiation until parturition. Ten cardiac parameters were measured: length, width and diameter of the heart; heart area; left and right ventricular dimensions; left and right atrial dimensions; and aortic and pulmonary artery diameter. Femoral length, biparietal diameter and abdominal cross-sectional area were also recorded. Regression equations were developed for each parameter of fetal body size, and linear and logarithmic models were compared. The model with the highest correlation coefficient was chosen to produce equations to calculate relative dimensions based on the correlations. Only the left-ventricular chamber differed between the two racial groups. Biparietal diameter was the independent parameter that produced the highest correlation coefficient for the most fetal cardiac dimensions, although good correlations were also observed using femoral length and abdominal cross-sectional area. Heart width and heart diameter were used as surrogates of cardiac development, as these measurements showed the best statistical correlation. Quantitative evaluation of fetal cardiac structures can be used to monitor normal and abnormal cardiac development.  相似文献   

Tenogenic induction of equine mesenchymal stem cells by means of growth factors and low-level laser technology     

Chiara Gomiero  Giulia Bertolutti  Tiziana Martinello  Nathalie Van Bruaene  Sarah Y. Broeckx  Marco Patruno  Jan H. Spaas 《Veterinary research communications》2016,40(1):39-48

Tendons regenerate poorly due to a dense extracellular matrix and low cellularity. Cellular therapies aim to improve tendon repair using mesenchymal stem cells and tenocytes; however, a current limitation is the low proliferative potential of tenocytes in cases of severe trauma. The purpose of this study was to develop a method useful in veterinary medicine to improve the differentiation of Peripheral Blood equine mesenchymal stem cells (PB-MSCs) into tenocytes. PB-MSCs were used to study the effects of the addition of some growth factors (GFs) as TGFβ3 (transforming growth factor), EGF2 (Epidermal growth factor), bFGF2 (Fibroblast growth factor) and IGF-1 (insulin-like growth factor) in presence or without Low Level Laser Technology (LLLT) on the mRNA expression levels of genes important in the tenogenic induction as Early Growth Response Protein-1 (EGR1), Tenascin (TNC) and Decorin (DCN). The singular addition of GFs did not show any influence on the mRNA expression of tenogenic genes whereas the specific combinations that arrested cell proliferation in favour of differentiation were the following: bFGF2 + TGFβ3 and bFGF2 + TGFβ3 + LLLT. Indeed, the supplement of bFGF2 and TGFβ3 significantly upregulated the expression of Early Growth Response Protein-1 and Decorin, while the use of LLLT induced a significant increase of Tenascin C levels. In conclusion, the present study might furnish significant suggestions for developing an efficient approach for tenocyte induction since the external administration of bFGF2 and TGFβ3, along with LLLT, influences the differentiation of PB-MSCs towards the tenogenic fate.  相似文献   

Detection of novel polymorphisms in the ckit gene of canine patients with lymphoma,melanoma, haemangiosarcoma,and osteosarcoma     

Irina Gramer  Martin Kessler  Joachim Geyer 《Veterinary research communications》2016,40(2):89-95

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Immunological and pathological investigations in equine experimental uveitis     

Galina P. Simeonova  Svetozar Z. Krastev  Radostin S. Simeonov 《Veterinary research communications》2016,40(3-4):107-115

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Detection of bovine torovirus in fecal specimens of calves with diarrhea in Japan     

Kirisawa R  Takeyama A  Koiwa M  Iwai H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(5):471-476

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Using midday stem water potential for scheduling deficit irrigation in mid–late maturing peach trees under Mediterranean conditions     

José Manuel Mirás-Avalos  Francisco Pérez-Sarmiento  Rosalía Alcobendas  Juan José Alarcón  Oussama Mounzer  Emilio Nicolás 《Irrigation Science》2016,34(2):161-173

Irrigation techniques that reduce water applications are increasingly applied in areas with scarce water resources. In this study, the effect of two regulated deficit irrigation (RDI) strategies on peach [Prunus persica (L.) Batsch cv. “Catherine”] performance was studied over three growing seasons. The experimental site was located in Murcia (SE Spain), a Mediterranean region. Two RDI strategies (restricting water applications at stage II of fruit development and postharvest) based on stem water potential (Ψ_s) thresholds (?1.5 and ?1.8 MPa during fruit growth and ?1.5 and ?2.0 MPa during postharvest) were compared to a fully irrigated control. Soil water content (θ_v), Ψ_s, gas exchange parameters, vegetative growth, crop load, yield and fruit quality were determined. RDI treatments showed significantly lower values of θ_v and Ψ_s than control trees when irrigation water was restricted, causing reductions in stomatal conductance and photosynthesis rates. Vegetative growth was reduced by RDI, as lower shoot lengths and pruning weights were observed under those treatments when compared to control. However, fruit size and yield were unaffected, and fruit quality was slightly improved by RDI. Water savings from 43 to 65 % were achieved depending on the year and the RDI strategy, and no negative carryover effect was detected during the study period. In conclusion, RDI strategies using Ψ_s thresholds for scheduling irrigation in mid–late maturing peach trees under Mediterranean conditions are viable options to save water without compromising yield and even improving fruit quality.  相似文献   

Measured and estimated water use and crop coefficients of grapevines trained to overhead trellis systems in California’s San Joaquin Valley     

Larry E. Williams  Matthew W. Fidelibus 《Irrigation Science》2016,34(6):431-441

The use of overhead trellis systems for the production of dry-on-vine (DOV) raisins and table grapes in California is expanding. Studies were conducted from 2006 to 2009 using Thompson Seedless grapevines grown in a weighing lysimeter trained to an overhead arbor trellis and farmed as DOV raisins for the first two years and for use as table grapes thereafter. Maximum canopy coverage for the two lysimeter vines across years was in excess of 80 %. Seasonal (15 March–31 October) evapotranspiration for the lysimeter vines (ET_Lys) was 952 mm in 2007 (farmed as DOV raisins) and 943 and 952 mm (when farmed as table grapes). The maximum crop coefficient (K _cLys) across all 4 years ranged from 1.3 to 1.4. These maximum values were similar to those estimated using the relationship where K _c is a function of the amount of shaded area measured beneath the canopy at solar noon (K _c = 0.017 × percent shaded area). Covering the lysimeter’s soil surface with plastic (and then removing it) numerous times during the 2009 growing season (1 June–14 September) reduced ET_Lys from an average of 6.4 to 5.6 mm day^?1 and the K _c from 1.07 to 0.93. A seasonal basal K _c (K _cb) was calculated for grapevines using an overhead trellis system with a 13 % reduction in the K _cLys across the growing season.  相似文献   

Crop response of drought-tolerant and conventional maize hybrids in a semiarid environment     

Ryan B. Mounce  Susan A. O’Shaughnessy  Brock C. Blaser  Paul D. Colaizzi  Steven R. Evett 《Irrigation Science》2016,34(3):231-244

In the High Plains, corn (Zea mays L.) is an important commodity for livestock feed. However, limited water resources and drought conditions continue to hinder corn production. Drought-tolerant (DT) corn hybrids could help maintain high yields under water-limited conditions, though consistent response of such hybrids is unverified. In this two-year study, the effects of three irrigation treatments were investigated for a DT and conventional maize hybrid, Pioneer AQUAMax P0876HR and Pioneer 33Y75, respectively. In 2013, the drier of the 2 years, irrigation amounts and crop water use (ET_c) were greater for the conventional hybrid, but grain water use efficiency (WUE) and harvest index were significantly greater for the DT hybrid. In 2014, grain yields and WUE were not significantly different between hybrids. However, irrigation amounts, ET_c and biomass yields were greater for the conventional hybrid. Results from both years indicate that the DT hybrid required less water to maximize grain yield as compared to the conventional hybrid. Producing relatively high yields with reduced amounts of water may provide a means for producers to continue corn production in a semiarid environment with declining water supplies.  相似文献