紫花苜蓿耐酸铝研究

紫花苜蓿是全球栽培面积最大的多年生豆科牧草,铝毒是制约其在酸性土壤推广种植的主要因子之一。主要综述了紫花苜蓿铝毒害机理、抗铝品种选育、抗铝生理生化、抗铝的分子机理以及抗铝的转基因研究等方面的主要进展,并对紫花苜蓿耐铝性研究中存在的问题和前景进行了讨论。     

紫花苜蓿耐铝的分子基础研究进展

紫花苜蓿Medicago sativa由于其对酸性土壤上植物铝毒害的敏感性而大大限制了其种植范围.要在占世界耕地40%的酸性土壤上进行推广种植,根本方法是培育耐高酸铝性的紫花苜蓿新品种.就近几年国内外在紫花苜蓿耐铝遗传分析,耐铝转基因苜蓿和其相关蛋白的分离鉴定等方面的研究进行综述,并介绍了亲缘性植物截形苜蓿M.truncatula的相关研究进展,基本明确了当前紫花苜蓿耐铝的研究方向、热点及存在的不足.     

烟草柠檬酸合成酶基因的克隆及其光诱导型植物表达载体的构建

紫花苜蓿为多年生优质豆科牧草。我国南方地区酸性土壤分布比较广,铝害比较严重,限制了紫花苜蓿在南方地区的推广利用。提高有机酸合成酶基因的表达活性,增加有机酸的合成与分泌,有利于增强植物的耐铝性。本研究根据Genebank中已知的烟草柠檬酸合成酶(Citrate Synthase, cs)基因的序列,通过RT-PCR从烟草总RNA中扩增cs基因的cDNA,亚克隆于T载体得到重组载体pMD18-cs,对pMD18-cs中的插入片断进行核酸序列分析确认为cs基因的cDNA全长。用光诱导型启动子(Rubisco,小亚基的启动子)和双元载体pPZP211构建了cs基因的光诱导型植物表达载体pPZP211-PrbcS-cs,为利用基因工程手段提高紫花苜蓿耐铝毒能力,促进其在南方地区推广利用奠定了物质基础。     

紫花苜蓿耐盐性研究进展

紫花苜蓿(Medicago sativa)是世界上最重要的豆科牧草之一,但盐渍化土地严重制约着其种植范围。培育耐盐新品种是降低盐渍化土地对紫花苜蓿生长和产量影响的有效途径。笔者综述了紫花苜蓿耐盐生理、盐诱导相关基因以及耐盐性育种方面的主要进展,并对紫花苜蓿耐盐性研究的前景进行了讨论。     

铝胁迫对紫花苜蓿不同种质材料的影响及综合评价

铝毒是紫花苜蓿（Medicago sativa）在南方酸性土壤地区种植的主要限制性因素之一。筛选能够在酸性富铝化土壤中生长优良的苜蓿材料,对于紫花苜蓿在南方大面积推广具有重要意义。本研究选用27份云南紫花苜蓿为材料,研究100 mg·kg^-1浓度铝胁迫处理下供试材料株高、脯氨酸、根系活力以及有机酸含量的变化。结果表明,铝对苜蓿生长具有明显的抑制作用,且不同材料反应敏感性不同。铝对供试苜蓿株高和根系活力有明显抑制作用;铝处理下苜蓿叶片中游离脯氨酸、有机酸含量显著积累（P<0.05）,所有供试材料的相对脯氨酸含量均大于100%,但不同材料相对有机酸含量表现差异较大。采用聚类分析及隶属函数法综合评价供试苜蓿材料的耐受性,以15,12,14,13号材料表现较优,可用于选育适应酸性富铝化土壤的苜蓿品种。     

转紫花苜蓿MsLEA2基因提高拟南芥耐铝毒性研究

MsLEA2基因是从紫花苜蓿中克隆到的胚胎晚期富集蛋白基因,属于LEA_2家族。以转基因拟南芥T_3代植株的3个株系为材料,从表型、生理和分子生物学三个方面研究铝胁迫下转MsLEA2基因拟南芥的耐铝毒性能。结果表明:铝胁迫下转基因株系的脯氨酸含量高于对照(野生型),丙二醛含量和电导率则低于对照且差异显著(P0.05),CAT、POD和SOD活性显著高于对照。初步证明转MsLEA2基因拟南芥的耐铝毒性能明显高于对照,紫花苜蓿的MsLEA2基因具有提高植物耐铝毒胁迫的能力。     

紫花苜蓿在江西的种植及效益分析

“苜蓿是金草，牛羊当成宝”。作为“牧草之王”的紫花苜蓿因其具有产量高、适应性强、品质优等特点，在我国北方已开始产业化生产。而南方由于春季雨水较多，夏季高温干旱，土壤酸性大，对其生长有一定的影响，还未大面积推广种植。其实，只要采取科学的管理措施，在我省种植苜蓿是可以成功并有很好收成的。近几年来。江苏、湖南、云南、浙江、四川、重庆等南方各省都已开始引种种植并推广了一定的面积，江西省畜牧技术推广站自20世纪80年代就开始进行引种试验并获得成功。     

南方农区紫花苜蓿发展潜力与种植模式研究进展

我国是紫花苜蓿生产大国之一,但南方农区紫花苜蓿的发展一直滞后,仅零星种植,生产效益不高。随着我国农业产业结构的调整以及畜牧业的蓬勃发展,农区对牧草产品的需求日益增加,紫花苜蓿的生产潜力正在逐渐显现。根据南方农区的生态条件和耕作制度设计紫花苜蓿与粮经作物复种的季节性种植模式,并配套相应的高产栽培技术,充分利用冬闲田和经济林晚秋至春季落叶季节进行速生栽培利用,能提高农区紫花苜蓿的生产效益。季节性栽培利用将是南方农区紫花苜蓿的重要发展方向。     

沙土地紫花苜蓿高产栽培技术

紫花苜蓿具有抗干旱、耐瘠薄、产量高、营养丰富，同时还具有增加土壤肥力、改良土壤结构的特点，成为广大种植户的首选品种，但由于河流滩地大多为砂质土，保水保肥能力差，需要特殊的栽培措施，才能获得高产。笔者在滩地种植紫花苜蓿多年，从中积累了一些经验。现将其总结如下，供广大农户参考。１品种选择目前，种植的紫花苜蓿品种株型分直立、斜生、匍匐三种，应选择再生能力和抗寒性都好的斜生株型。适宜在沙土地种植的进口紫花苜蓿品种有阿尔冈金、金皇后、德宝、三得利等；国内品种有香味浓和其它一些地方品种。但在实际生产中，还要…     

44个紫花苜蓿品种的酸铝适应性与耐受性评价

为了解紫花苜蓿在贵州地区的适应性及耐酸铝胁迫机理，以44份紫花苜蓿品种为研究对象，研究紫花苜蓿处于酸铝胁迫下的生理变化，并揭示其生理变化与耐酸铝胁迫间的关系。利用基因与环境互作模型对两个地点1年的紫花苜蓿进行产量分析，筛选出阿尔冈金、新疆大叶苜蓿、Trifecta、Vernal和中牧1号苜蓿5个耐酸铝强适应品种。利用敏感型UC-1465和耐受型阿尔冈金进行酸铝胁迫试验。结果表明：相同处理下，耐受型紫花苜蓿的电导率、相对铝含量、死亡率显著低于敏感型；紫花苜蓿对酸铝胁迫的响应主要通过柠檬酸、苹果酸、乙酸、酒石酸、反丁烯二酸和草酸的显著（P<0.05）增加来体现，其中苹果酸的合成和分泌增多可能是其耐酸铝胁迫的重要原因。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein