降雨量和温度变化对麻花艽叶片光合作用及相关生理参数的影响

以人为控制降雨量和LI-6400便携式光合测定系统控制温度方法,测定分析了降雨量和温度变化对高寒草甸典型组成植物——麻花艽叶片净光合速率及相关生理参数影响。结果显示:麻花艽叶片净光合速率、气孔导度、胞间CO2浓度、蒸腾速率在降雨量增加下较高、自然降雨量下次之、降雨量减少处理下较低;水分利用效率在降雨量增加下较低、自然降雨量下次之、降雨量减少下较高,温度为25℃与15℃下差异不显著。麻花艽叶片净光合速率在光合有效辐射强度为0~800μmol.m-2.s-1时随光合有效辐射强度增加而增加,800~1200μmol.m-2.s-1时达最大,1200~3000μmol.m-2.s-1时变化不大;气孔导度和蒸腾速率随光合有效辐射强度增加而增加;胞间CO2浓度在光合有效辐射强度为0~800μmol.m-2.s-1时随光合有效辐射强度增加而下降,800~3000μmol.m-2.s-1时变化不大;水分利用效率在光合有效辐射强度为0~800μmol.m-2.s-1时随光合有效辐射强度增加而增加,800~3000μmol.m-2.s-1时呈现下降趋势。降雨量减少将使高寒草甸植物叶片净光合作用速率、气孔导度、胞间CO2浓度和蒸腾速率降低。     

狭叶锦鸡儿光合及水分生理生态特性的日变化研究

使用LI-6400便携式光合测定仪,对自然条件下鄂尔多斯高原狭叶锦鸡儿的光合作用和水分生理生态特性进行了研究,结果表明:狭叶锦鸡儿净光合速率(Pn)的日变化呈双峰型,峰值分别出现在10:00和16:00,有明显的光合"午休"现象;蒸腾速率(Tr)呈单峰型,在10 ∶00达到峰值;水分利用效率(WUE)呈双峰型,上午高于下午.Pn对光合有效辐射(PAR)、大气温度(Ta)和大气相对湿度(RH)的响应程度不同,其中对Ta和RH的响应程度均达到显著水平,而对PAR的响应相对较低,未达到显著水平.狭叶锦鸡儿的光补偿点为86.88μmol·m2·s-1,光饱和点为875.00μmol·m-2·s-1,光合最适温度为30.92℃,最适空气相对湿度为33.91%.     

5个热带禾本科牧草品种的光合-光响应特性研究

在桂林地区采用Li-6400便携式光合测定系统测定5个热带禾本科牧草品种的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、水分利用效率(WUE)等生理特性指标。结果显示:1)5个牧草品种的Pn、Tr和Gs均随PAR增强而增大,WUE随PAR增强先增大后减小,除桂牧一号[(Pennisetum purpureum cv. Mott)×(P.americanum×P.purureum)]cv. Guimu No.1在PAR为1 500μmol/(m2.s)时达到最大值外,其余均在PAR为600μmol/(m2.s)时达到最大值。2)3个杂交品种的最大光合速率(Amax)与光饱和点(LSP)均显著高于2个雀稗品种(P0.05),最大Pn和Tr均高于2个雀稗属品种。研究表明:5个热带牧草品种均能很好的适应当地的环境。     

中药接骨草光合生理特性研究

以野生接骨草(Sambucus chinensis Lind.)为研究对象,用便携式光合仪测定其光响应曲线和CO2响应曲线,同时测得了光合作用其他参数,旨在加深对接骨草光合特性和生理特性的认识,为其高产栽培和管理提供依据.结果表明:接骨草的叶片光饱和点(LSP)为308.97 μmol·m-2·s-1,光补偿点(LCP)为7.94 μmol·m-2·s-1,最大净光合速率(Pmax)为10.24μmol·m-2·s-1,暗呼吸速率(Rd)为-0.27μmol CO2·m-2·s-1,表观量子效率(AQY)为0.03,说明接骨草属喜阴性植物,能较好地利用弱光进行光合作用;CO2补偿点为55.63 μmol·mol-1,CO2饱和点为822.59 μmol·mol-1,羧化效率为0.04,表现出较大光合作用潜力和较广的生存适应能力.     

石漠化地区单播与混播牧草光合差异研究

利用英国Lcpro+便携式测定系统研究了石漠化地区多年生黑麦草和白三叶的单播与混播群落光合日变化特征差异。结果表明:混播牧草由于其种间竞争与互补优势提高了其混播组合的净光合速率及水分利用效率。多年生黑麦草(净光合速率5.09±3.42μmol CO2·m-2·s-1、水分利用效率1.29±0.84μmol CO2·mmol-1 H2O)-白三叶(7.53±3.65μmol CO2·m-2·s-1、水分利用效率1.68±0.67μmol CO2·mmol-1 H2 O)混播草地群落的净光合速率及水分利用效率高于多年生黑麦草(净光合速率4.82±2.79μmol CO2·m-2·s-1、水分利用效率1.22±0.95μmol CO2·mmol-1 H2 O)、白三叶(净光合速率6.97±3.26μmol CO2·m-2·s-1、水分利用效率1.52±0.65μmol CO2·mmol-1 H2 O)的单播草地群落。混播处理的多年生黑麦草蒸腾速率(4.24±2.43 mmol H2O·m-2·s-1)高于单播(4.22±2.43mmol H2O·m-2·s-1)处理,白三叶混播处理的蒸腾速率(4.55±1.98 mmol H2O·m-2·s-1)则低于单播(4.64±1.98mmol H2O·m-2·s-1)处理。本研究对维持混播草地群落的稳定性,探寻种间竞争机理,优化牧草种植模式,科学发展喀斯特草地畜牧业具有一定的理论与现实意义。     

三裂叶蟛蜞菊光合生理特性对光合有效辐射增强的响应

三裂叶蟛蜞菊是华南地区重要的园林绿化植物。在人工控制光合有效辐射(PAR)条件下,测量了三裂叶蟛蜞菊在深秋和冬季的净光合速率(Pn),蒸腾速率(Tr),胞间CO2浓度(Ci)和气孔导度(Gs)等光合生理特性对连续光照强度增强的响应。结果表明:Tr、Pn均随PAR的增强而增大,且增幅稳定;Gs在PAR增强的起始阶段先下降,从200μmol/(m2·s)后,逐渐上升,尤其11 月较明显;Ci随着PAR的增强而逐渐减少,在PAR为2 000μmol/(m2·s)后趋于平衡。温度对三裂叶蟛蜞菊光合生理特性的影响较显著,但若光照充分,其光合速率也能提高。三裂叶蟛蜞菊有较高的水分利用率,表明它比较耐干旱。     

冷饭团光合日变化及土壤水分对其光合特性的影响*

适合的土壤水分和光照强度更有利于植物生长。以冷饭团 (Kadsura coccinea)小苗为研究对象,采用LI-6400便携式光合仪对其光合日变化及不同土壤水分条件下的光合指标进行测定并分析。结果表明,冷饭团净光合速率(Pn)日变化呈“双峰”型,有轻微“午休”现象。不同有效辐射(PAR)阶段,不同土壤含水率实验组变化趋势不同,在PAR为200~600 μmol.(m2.s)-1阶段,各实验组均达到较高的Pn值,且实验组间无显著性差异(P>0.05)。弱光条件下[PAR<200 μmol.(m2.s)-1],随着土壤水分减少,光补偿点(LCP) 减小,对弱光的利用能力增加;强光条件下[PAR>600 μmol.(m2.s)-1],除含水率19.6%实验组,Pn、蒸腾速率(Tr)、气孔导度(Gs) 呈升高或稳定趋势变化外,其余5组随着含水率的减小而减小,水分利用率(WUE)先减小后平稳,且随含水率减小而增大。土壤含水率为19.6%,PAR 为600 μmol.(m2.s)-1] 是冷饭团较为适合生长的环境条件。     

淫羊藿的光合特性及其影响因素研究

旨在研究淫羊藿(Epimedium brevicornu Maxim.)的光合作用的日变化特征以及影响其光合作用的因素,为合理开发与人工种植淫羊藿提供参考依据。利用Li-6400光合作用测定系统测定淫羊藿叶片光合作用的日变化,测量光合速率(Pn)、相对湿度(RH)、空气温度(Tar)、气孔导度(Gs)、胞间CO_2浓度(Ci)、土壤温度(Ts)、蒸腾速率(Tr)、水分利用效率(WUE)、叶片温度(Tl)、光合有效辐射(PAR)等生理生态因子,并通过相关性分析明确淫羊藿净光合速率和生理生态因子之间的关系。结果发现,淫羊藿的净光合速率呈现双峰曲线,两个峰值分别是10∶00和14∶00,在上午10∶00时,淫羊藿叶片净光合速率是全天的最高值3.39μmol CO_2/(m~2·s);相关性分析表明,光合有效辐射(PAR)、空气温度(Tar)、气孔导度(Gs)、胞间CO_2浓度(Ci)、大气相对湿度(RH)、蒸腾速率(Tr)这6个生理生态因子对淫羊藿的净光合速率有显著性影响。淫羊藿具有明显的"光合午休"现象,在淫羊藿种植中要对淫羊藿进行遮阴以及适当的灌水和通风,以改善空气相对湿度,补充植株水分,增大叶片的气孔导度,提高光合速率,以达到优质高产的目的。     

不同磷水平对紫花苜蓿光合作用和根瘤固氮特性的影响

采用砂培方法,在营养液条件下研究不同磷水平对甘农3号紫花苜蓿(Medicago sativa‘Gannong No.3 ')光合作用和根瘤固氮特性的影响.结果表明:在其他营养充分供应的基础上,适当提高磷水平可以显著增大甘农3号紫花苜蓿叶片的气孔导度和光合速率,减小蒸腾速率,并提高叶片中叶绿素含量,增大叶面积,增加叶片数,同时使根瘤数目增多,根瘤重增加,固氮酶活性显著增强.光合作用在磷水平为1500 μmol·L-1时最强,此时叶片蒸腾速率为4.27mmol·m-2·s-1,气孔导度为347.54 mmol.m-2·s-1,光合速率为10.37 μmol·mol-1,胞间CO2浓度为307.28μmo1·mol-1;叶绿素含量、叶面积和叶片数都随着磷水平的增大而呈现出先增大后减小的趋势,叶面积在磷水平为1500 μmol·L-1时达到最大值1.21 cm2;叶片数在磷水平为250 μmol·L-1时达到最大值26.50个,继续增大磷浓度至1500 μmol·L 1时叶片数仍显著高于对照;根瘤数和根瘤重随磷水平的增大持续增大;固氮酶活性在磷水平为1500 μmol·L-1时最强达57.1 μg·g-1·h-1.综合考虑,磷水平在1500 μmol·L-1时为最佳值,过高或过低的磷水平都不利于甘农3号紫花苜蓿的正常生长发育.     

上海地区引种地被石竹蒸腾特征及影响因子分析

采用Li-6400光合作用测定仪对在上海地区引种的地被石竹蒸腾速率日变化、季节变化特征进行研究.结果表明:(1)地被石竹蒸腾速率日变化为单峰型,峰值出现在11:00～12:00;蒸腾速率的季节变化为单峰曲线,6月份最高,达到12.72mmol·m2·s-1,11月份最低,仅为1.31mmol·m-2·s-1,生长季叶片平均值为6.07mmol·m-2·s1.(2)直接影响蒸腾速率日变化的主要因子春季(3月下旬)为光合有效辐射和相对湿度;夏季(6月下旬)为光合有效辐射和气温;秋季(10月初)为光合有效辐射、气温、胞间CO2浓度和相对湿度.(3)地被石竹三季单位叶面积平均H固碳量、日释氧量、日蒸腾释水量、日吸热量春季分别为12.16g·m-2·d1、8.85g·m-2·d-1、2480.89g·m2·d-1、6065.90KJ·m-2·d-1,夏季为12.46g·m-2·d1、9.07g·m-2·d-1、8283.25g·m-2·d-1、19940.75KJ·m2·d-1,秋季为10.29g·m-2·d-1、7.48g·m-2·d-1、2102.56g·m-2 ·d-1、5098.57KJ·m-2·d-1.     

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