磷、钾对番茄可溶性碳水化合物分配的影响

以番茄苗为试验材料,研究了不同浓度磷、钾对番茄植株可溶性碳水化舍物分配的影响。结果表明：磷、钾亏缺处理45d后,与正常磷、钾处理相比,磷亏缺的植株冠根比下降,而钾亏缺的植株冠根比则上升。钾亏缺的植株叶片中,蔗糖、还原糖和总可溶性糖含量均表现为上升,根中则表现为下降。磷亏缺的植株叶片中,蔗糖、还原糖和总可溶性糖含量基本不变,而在根中则表现为不同程度的增加。在叶和根的总可溶性糖中,钾亏缺和磷亏缺的植株,根部总可溶性糖所占的比例分别为10．71％和45．65％,两者的对照分别为28．63％和33．11％。上述结果表明,钾和磷在光合产物的转运中所起的作用不同,植株中营养元素亏缺不同,干物质在不同部位的分配也不同。     

Root zone temperature alters storage root formation and growth of sweetpotato

Large mounds amended with plant residues are a common cultivation method for sweetpotato (Ipomoea batatas) in the western parts of the Papua New Guinea highlands, with a suggested benefit of elevated root zone temperature (RZT) from decomposition. This study aimed to evaluate whether RZT affects the formation and growth of sweetpotato storage roots. Experiments evaluated the effects of a constant elevated RZT on the Beauregard cultivar and of a short‐term increase in RZT on the Beauregard and Northern Star cultivars. Plants were grown in 18‐L pots divided into a control compartment (constant RZT at 20°C) and a treated compartment (RZT at 30, 40 or 50°C). Constant elevated RZT was maintained until harvest, while short‐term increase in RZT occurred in weeks 2 and 3 only. Constant elevated RZT did not affect the total number of storage roots, but RZT of 30°C and above reduced the dry‐biomass of storage roots. The short‐term increase in RZT did not alter the total number or dry‐biomass of storage roots in Beauregard, while both of these attributes were reduced at RZT of 40°C or above in Northern Star. Elevated RZT inhibited dry‐biomass accumulation of storage root, with a more pronounced impact at constant elevated RZT. These results demonstrate that any benefits of the mound culture on sweetpotato yield production do not arise through the influence of temperature elevation.     

大针茅根系构型对草地退化的响应

本研究对锡林郭勒典型草原区轻度、中度、重度和极度4个退化梯度草地中大针茅(Stipa grandis)根系构型进行研究。结果表明,1）根分叉数、根表面积和总根长3个参数是分析大针茅根系构型在不同退化程度草地中变化的主要指标,其中根分叉数对该变化的解释力最强,3个参数的累积贡献率为90.7%;2）从轻度、重度到极度退化程度的草地系列中,大针茅的根系构型小型化趋势明显;3）中度退化程度的草地中大针茅根系构型小型化特别明显;4）根系构型小型化最终导致整个植物体小型化,因此在群落退化演替进程中大针茅的建群种作用逐渐减弱并最终为其他优势种取代。     

土壤脱湿过程中NaCl胁迫对羊草生长和矿质元素吸收的影响

用不同盐分浓度的NaCl中性盐对羊草进行胁迫,探讨在土壤脱湿过程中,NaCl胁迫对羊草生长和矿质元素吸收分配的影响。结果表明,当土壤溶液NaCl浓度小于125mmol/L(土壤总盐小于o．34％)时,盐分胁迫对羊草株高、根长、干物质积累量和相对生长率(RGR)无显著影响,且根系的钾钠吸收选择性和运输选择性随盐度处理水平的增加而增强。但当NaCl浓度超过225mmol/L(土壤总盐大于0．53％)后,其株高、根长、干物质积累量和相对生长率(RGR)随盐度增加而显著降低(P＜0．05),根系的钾钠吸收选择性和运输选择性也随盐度处理水平的增加而逐渐减弱。NaCl胁迫条件下,羊草对K、Ca的比吸收率(SAR)降低,茎叶K、Ca含量随盐度的增加显著减少(P＜0．05),Na、Cl含量则均随盐度的增加而显著提高,植株K／Na降低。羊草茎叶的盐分离子(Na^ 、Cl^-)含量与相对生长率(RGR)之间呈显著的负相关关系。     

低温弱光对苗期紫花苜蓿根颈生理特性的影响

以秋眠级不同的2个紫花苜蓿Medicago sativa品种(巨人201和WL414)为试验材料,研究了其在低温(0~5℃和5~10℃)与弱光[50和100μmol/(m2.s)]互作处理条件下的生理响应。结果表明:紫花苜蓿根颈在低温弱光胁迫下启动了自身应激机制,对逆境胁迫做出了适应性反应,相同弱光条件下,低温0~5℃比5~10℃对根颈的影响显著,过氧化物酶活性上升幅度较小,而超氧化物歧化酶活性的下降和丙二醛含量的增加幅度均较大;相同低温处理,弱光50μmol/(m2.s)处理对根颈生理指标影响更为显著,过氧化物酶活性上升、超氧化物歧化酶活性下降和丙二醛含量增加幅度大于弱光100μmol/(m2.s)处理;巨人201各项指标的变化都优于WL414,表明巨人201抗寒耐弱光能力都可能优于WL414。     

反刍动物小肽的生理特征与营养研究进展

小肽是动物降解蛋白质过程中产生的中间产物,蛋白质在动物消化道内降解成游离氨基酸和小肽后被吸收。大量试验结果表明,反刍动物以肽吸收为主要形式,并且其在氨基酸消化、吸收和降解中起着重要作用。作者对小肽生理特征及营养等方面的研究现状进行了综述。     

维生素E吸收、转运、代谢机理的研究进展

维生素E是对动物体十分重要的脂溶性维生素。动物对维生素E的利用需要经过肠道的吸收、血液中脂蛋白的转运、肝脏的储存和调控及机体各个组织的摄取和代谢;这些过程涉及到多种生理学机制,包括多种载体的转运、酶类的催化及其他营养素的互作等。了解这些机制有助于人们探索动物体利用维生素E的关键点,继而通过调控这些关键点促进动物对维生素E的利用。作者简要总结了有关维生素E在动物及人类体内吸收、转运、代谢过程机理的最新研究结果。     

火焰原子吸收光谱法测定奶粉中锌的含量

采用原子吸收光谱法测定多种品牌奶粉中锌的含量,对干法消化奶粉所用混合酸的组成、比例等试验条件进行了研究,其最佳样品处理条件为:硝酸-高氯酸(4+1)作为溶解用酸,1 mol/L盐酸作为定容用酸,测定结果的相对标准偏差小于2%.     

Factors Influencing the Bioavailability of Peroral Formulations of Drugs for Dogs

The oral route is presently the preferred route of drug delivery. Poor oral bioavailability results in variable concentrations of drugs in the plasma and variable pharmacological responses, in addition to higher product costs. The unique canine physiology, anatomy and biochemistry makes designing canine dosage forms a challenging exercise. This article reviews the physicochemical, physiological, pharmacokinetic, pharmacological and formulation factors that can influence the drug availability of the oral formulations in dogs in an effort to provide a source of data to aid development of canine drug products with superior bioavailability.     

Effect of different inspired fractions of oxygen on F-shunt and arterial partial pressure of oxygen in isoflurane-anaesthetized and mechanically ventilated Shetland ponies

ObjectiveTo determine the effect of fraction of inspired oxygen (FiO₂) on intrapulmonary shunt fraction as measured by F-shunt in ponies during isoflurane anaesthesia.Study designProspective, randomized clinical study.AnimalsA group of 23 adult Shetland ponies undergoing a total of 32 anaesthetic procedures.MethodsPonies were premedicated intravenously (IV) with detomidine (0.01 mg kg^–1) and either morphine (0.1 mg kg^–1) or butorphanol (0.02 mg kg^–1). Anaesthesia was induced with ketamine (2.2 mg kg^–1) and midazolam (0.07 mg kg^–1) administered IV. Ponies were randomly allocated to maintenance of anaesthesia with isoflurane in oxygen (group TH; FiO₂ = 0.95) or a mixture of oxygen and medical air (group TL; FiO₂ = 0.65); all ponies were given a constant rate of infusion of detomidine. Animals were mechanically ventilated to maintain PaCO₂ between 40 and 50 mmHg. Arterial blood gas analysis was performed every 30 minutes. The F-shunt equation was calculated for each time point T0, T30, T60 and T90. Data were analysed using linear mixed model analysis and presented as mean ± standard deviation (p < 0.05).ResultsPaO₂ was greater in group TH than in group TL (TH: 406 ± 90, 438 ± 83, 441 ± 69 and 464 ± 53 mmHg versus TL: 202 ± 90, 186 ± 84, 172 ± 85 and 191 ± 98 mmHg at T0, T30, T60 and T90, respectively; p < 0.0001). In TH, F-shunt was < TL. Significant differences were found at T60 (TH: 13.2% ± 4.3 versus TL: 19.4% ± 8.3; p = 0.016) and T90 (TH: 11.7% ± 3.5 versus TL: 18.6% ± 9.5; p = 0.036).Conclusions and clinical relevanceOur findings do not support a beneficial effect of using a reduced FiO₂ to improve oxygenation in anaesthetized and mechanically ventilated Shetland ponies.