胍丁胺对大鼠应激性体温升高的抑制作用

目的：观察胍丁胺（AGM）是否能降低或反转应激性体温过高反应。方法：61只雄性SD大鼠随机分为3部分,每部分再分为对照组和AGM组。在实验过程中,人工气候箱和开放实验箱内的温度均保持在22℃。①用无线遥测技术连续测量大鼠的体温和活动,观察腹腔注射AGM对安静状态下大鼠正常体温和活动的影响（n=8）;②将大鼠放置在开放实验箱中60 min复制应激性体温过高的模型,用无线遥测技术连续测量开放实验箱内大鼠体温和活动的变化（n=7~8）;③用美国哥伦布公司动物代谢分析系统测量AGM对大鼠能量代谢的影响（n=7）。结果：①腹腔注射AGM 80 mg/kg能引起正常大鼠出现明显低温反应（-0.46±0.11）℃,而注射AGM 40 mg/kg则对正常体温无明显影响。②对照组大鼠腹腔注射生理盐水后,置于开放实验箱内体温升高达（0.78±0.16）℃;给大鼠注射AGM 40或80 mg/kg后,置于开放实验箱内60 min时,体温则分别降低（0.34±0.11）℃和（0.81±0.14）℃。③AGM 80 mg/kg能明显降低大鼠的耗氧量和产热量。结论：AGM能引起正常大鼠出现低温反应和明显翻转应激性体温升高反应,其作用可能与AGM能降低能量代谢有关。     

5-HT1A受体阻断剂对乙醇引起大鼠低体温和行为性体温调节反应的影响

目的：观察5-羟色胺1A （5-HT_1A）受体阻断剂p-MPPI对乙醇引起大鼠低体温和行为性体温调节反应的影响。方法：用无线遥控测温技术记录成年雄性SD大鼠体核温度和活动的变化。用无线遥测温度梯度仪监测大鼠体核温度和行为性体温调节活动,将大鼠置于15℃~40℃的温度梯度箱内,并允许动物自由选择箱内温度,观察乙醇（3 g/kg）引起低体温和行为性体温调节的反应以及5-HT_1A受体阻断剂p-MPPI （1 mg/kg）对其效应的影响。结果：①乙醇能引起大鼠快速的体温降低反应,同时动物选择较低的环境温度。②5-HT_1A受体阻断剂p-MPPI能明显阻断乙醇引起的低体温和行为性体温调节变化。结论：①乙醇能使体温调定点降低,因为乙醇引起低体温时,大鼠选择较冷环境温度区;②5-HT可能参与乙醇引起低体温与行为性体温调节活动。     

第四脑室注射吗啡对应激性高血粘度与血压升高的影响

实验用Wistar大鼠99只,雄性250g左右,随机分三组:对照组、悬吊加束缚组、悬吊一束缚加电针组。结果:(1)清醒大鼠束缚加悬吊可引起应激性高血粘度和血压升高,切断双侧颈迷走神经后上述现象仍存在。静脉注射心得安(0.3mg/ml)或酚妥拉明(0.3 mg/ml)对正常大鼠血压、血粘度影响不大,但对应激性血压升高均有抑制作用。静脉注射心得安还可降低应激性高血粘度。(2)电针大鼠右后肢对应激性高血粘度和血压升高有抑制作用。(3)第四脑室内注射吗啡(10μg/10 μl)15或30min后可降低应激性高血粘度和血压升高,注入等量生理盐水无变化。若在第四脑室注射纳洛酮 (10μg/10μl)则可部分阻断电针右后肢对悬吊-束缚诱发的高血粘度和血压升高的抑制作用。结果提示:悬吊-束缚大鼠可能兴奋交感神经传出系统经激活β受体诱发应激性高血粘度阻断α或β受体可降低应激性血压升高。脑内阿片肽可抑制应激性高血粘度和血压升高,脑内河片肽受体的激活可参与电针后肢对应激性高血粘度和血压升高的抑制作用。     

家兔肺动脉内注射乙酰胆碱对肺动脉血压的影响

在65只氨基甲酸乙酯麻醉的兔,向肺动脉内注射2—4μg乙酰胆碱(ACh),可使颈动脉压出现短暂下降,回升时,肺动脉压可出现升压或降压两种反应,但以升压反应较为多见。发生这两种反应时,心率无明显变化。上述颈动脉降压反应、肺动脉升压和降压反应均能被阿托品阻断。乙酰胆碱引起的肺动脉升压反应可以被胆碱能N-受体阻断剂六甲双铵阻断,亦可被α-受体阻断剂酚妥拉明部分逆转。β-受体阻断剂心得安能部分逆转乙酰胆碱降低颈动脉压的作用,但对乙酰胆碱升高或降低肺动脉压的作用无任何影响。 结果表明,当血液中乙酰胆碱水平升高使肺动脉压下降主要是由于乙酰胆碱直接使肺血管平滑肌舒张。而促使肺动脉压上升的原因,是由于乙酰胆碱一方面直接使肺血管平滑肌收缩;另一方面还可激活交感神经节中N-受体,促进去甲肾上腺素释放,后者与α-受体结合而引起肺血管收缩所致。     

家兔第四脑室注射乙酰胆碱对肺动脉血压的影响

本工作将乙酰胆碱(ACh)注入麻醉家兔第四脑室,观察其对肺动脉血压的影响。结果发现(1)脑室注射50—100μg ACh后,肺动脉压和颈动脉压均下降。与此同时心率也出现一过性减慢。(2)切断两侧颈部迷走神经,ACh不再使心率减慢,但其降低肺动脉压和颈动脉压的作用不受到任何影响。(3)预先由第四脑室注射阿托品,可阻断AGh引起的肺动脉降压反应和颈动脉降压反应。(4)第四脑室注射六甲双铵或酚妥拉明,均不能阻断这二个降压反应。(5)第四脑室注射心得安不能阻断ACh引起的肺动脉降压反应,但能阻断ACh降低颈动脉压的作用。 实验结果表明:脑中ACh水平升高可通过激活胆碱能M-受体引起肺动脉压和颈动脉压下降;在ACh引起的颈动脉降压反应的中枢环节中有肾上腺素能β-受体活动参与;而且ACh降低肺动脉压和颈动脉压的作用不是通过迷走神经实现的,可能是由于延髓交感缩血管中枢紧张性降低所造成的。     

体温过高对大鼠脑干听觉诱发电位和中潜伏期反应的影响

目的 :探讨体温过高对大鼠脑干听觉诱发电位 (BAEP)和听觉中潜伏期反应 (MLR )的影响。方法 :诱发电位仪颅表记录大鼠BAEP和MLR ;体表物理升温法逐步升高麻醉大鼠体温 ,传感探头式数字体温计监测大鼠直肠体温 ;主要观察BAEP和MLR的波峰潜伏期 (PL)、波峰间潜伏期 (IPL)和波幅随体温升高而发生的变化及它们消失的临界体温。结果 :BAEP各波PL及Ⅰ Ⅱ、Ⅰ Ⅲ、Ⅰ ⅣIPL随体温升高 ( 3 7～ 41.5℃ )而逐步缩短 ,但当体温升高至 42℃和超过 42℃时各波PL及Ⅰ Ⅱ、Ⅰ ⅣIPL不再继续缩短 ,并略有反向延长 ;MLR各波PL和P1 P3、P2 P3IPL也随体温升高 ( 3 7～ 43℃ )而缩短。随体温升高 ,BAEP和MLR波幅的主要表现为降低 ,特别是在体温升高至42℃以后。BAEP和MLR在体温 ( 4 3 .1± 0 .5)℃时出现不可逆性消失 ,且两者同步消失。结论 :体温过高对大鼠BAEP和MLR有相似的显著影响 ,体温过高至一临界值时会造成BAEP和MLR的不可逆性损害。     

家兔脊髓蛛网膜下腔注射乙酰胆碱对血压和心率的影响

将乙酰胆碱(ACh)注入麻醉家兔脊髓蛛网膜下腔,观察其对心血管活动的影响。结果表明:(1)脊髓蛛网膜下腔注射50～100μg ACh可使血压下降,心率减慢;(2)预先由脊髓蛛网膜下腔注射阿托品,可阻断ACh引起的降压和降心率作用;(3)脊髓蛛网膜下腔注射六甲双铵、酚妥拉明或心得安均不能阻断上述ACh的心血管反应;(4)切断两侧颈部迷走神经,ACh不再使心率减慢,但其降低血压的作用不受到任何影响。 脊髓中ACh水平升高可通过激活胆碱能M-受体引起血压下降和心率减慢。ACh的这种降压作用既没有中枢肾上腺素能受体活动参与,也不是通过迷走神经实现的,可能是由于脊髓交感血管中枢紧张性降低所造成的。     

下丘脑室旁核内GABA在中枢高渗刺激诱发的心血管反应中的作用

目的：探讨下丘脑室旁核（PVN）内的γ-氨基丁酸（GABA）在中枢高渗刺激诱发的应激性心血管反应中的作用及其机制。方法：在清醒自由活动大鼠,用脑部微量透析法和高效液相色谱法观察中枢高渗刺激对PVN区域GABA含量的影响,并同时记录血压和心率的变化;用GABAA受体阻断剂Bicuculline或GABAB受体阻断剂Saelofen直接灌流PVN区并给予中枢高渗刺激,进一步探讨PVN区GABA在中枢高渗刺激诱发的应激性心血管反应中的作用。结果：①PVN局部灌流0．6mol／L盐水时,血压和心率都显著增加（均为P〈0．01）,同时,PVN区细胞外液中GABA水平也明显增加到刺激前的561．96％±173．96％（P〈0．05）;②PVN局部灌流Bicuculline或Saclofen的同时,给予0．6mol／L盐水的刺激,可使高渗刺激引起的血压增加幅度明显降低（均为P〈0．01）,而心率的增加幅度未受明显影响（均为P〈0．05）。结论：中枢高渗刺激可引起PVN内GABA的分泌,而后者可通过GABAA和GABAB受体产生血压的升高反应。     

脑室注射5-HT对应激后胃粘膜中ATP酶活性及ATP和ADP含量的影响

中枢5-羟色胺(5-HT)可通过兴奋下丘脑-垂体-甲状腺轴加重大鼠冷冻加束缚应激性溃疡。本工作进一步观察了脑室注射5-HT对胃粘膜代谢的影响及其与甲状腺激素的关系。应激180min大鼠的胃粘膜ATP酶的活性较非应激发对照鼠升高42.6％;如应激前10min向侧脑室注射5-HT50μg或腹腔注射四碘甲腺原氨酸(T_4)200μg/kg,均匀进一步提高应激后胃粘膜ATP酶的活性。在侧脑室注射5-HT后应激180min的鼠,血浆三碘甲腺原氨酸(T_3)和T_4水平均与胃粘膜ATP酶的活性呈明显的正相关关系。用高效液相层析测定观察到,应激鼠胃粘膜ATP和ADP水平均明显低于非应激鼠,分别为非应激鼠的70.3％和76.8％。腹腔注射T_4进一步减少应激后胃粘膜ATP和ADP的水平。这些结果提示,中枢5-HT可能通过甲状腺激素提高胃粘膜ATP酶的活性,使ATP和ADP含量下降,这可能与其加重溃疡的机制有关。     

胍基丁胺对大鼠血流动力学的影响及其细胞机制

在麻醉大鼠研究静注胍基丁胺（ＡＧＭ）对血流动力学的影响,并初步探讨其机制。结果如下：（１）静注ＡＧＭ（１０ｍｇ／ｋｇ）后,ＨＲ,ＭＡＰ,ＬＶＰ,±ＬＶｄｐ／ｄｔｍａｘ,ＣＩ和ＴＰＲＩ均明显下降;（２）预先静注ＮＯＳ抑制剂ＬＮＮＡ（１５ｍｇ／ｋｇ）或腹腔内注射鸟苷酸环化酶抑制剂亚甲基蓝（５０ｍｇ／ｋｇ）,均不能阻断ＡＧＭ的降压作用;（３）预先静注咪唑啉受体和α２肾上腺素能受体阻断剂ｉｄａｚｏｘａｎ（２ｍｇ／ｋｇ）则可明显阻抑ＡＧＭ的降压效应。以上结果表明,ＡＧＭ对麻醉大鼠的降压机制,在于显著抑制心肌收缩性而使心输出量降低,以及舒张外周血管致使总外周阻力下降;此效应似主要由ＩＲ和／或α２ＡＲ所介导。     

壳聚糖酶的克隆表达与壳寡糖的制备分析

目的:克隆壳聚糖酶基因于大肠杆菌中实现高表达,制备壳寡糖。方法:以枯草芽孢杆菌总DNA为模板扩增壳聚糖酶基因(CSN),克隆至载体pET23a(+)上,转化菌株BL21(DE3)。重组子经0.5 mmol/L IPTG诱导后,SDS-PAGE和质谱检测与鉴定重组酶。酶纯化后水解壳聚糖,薄层色谱分析其水解产物。结果:质谱证明壳聚糖酶(31.5kDa)成功表达,表达量占菌体总蛋白的45%左右。纯化后重组酶浓度为900 mg/L,纯度95%、回收率85%,酶活力为10 000 U/mg。壳聚糖降解产物为壳二糖至壳四糖。结论:原核表达载体pET23a(+)-CSN构建正确,壳聚糖酶表达量与活性高,适用于水解壳聚糖制备壳寡糖。     

国内外蝗害治理技术现状与展望

本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...     

放牧对牧草光合作用、呼吸作用和氮、碳吸收与转运的影响

研究放牧对草地植物生理活动的影响,对于揭示草地放牧演替的生理机制有重要意义.大量研究表明,家畜放牧对牧草光合作用、呼吸作用以及C和N吸收与转运的影响,可以分为生理伤害和生理恢复2个阶段.放牧通过改变草地冠层结构影响牧草光合作用,净光合作用速率短期内迅速下降,随着叶面积指数增加又逐渐上升,呼吸作用有相似的变化趋势.牧草放牧后再生长所需的C和N最初主要来自根系和留茬中的贮藏物质,此后随着牧草生长恢复逐渐由同化作用供给,C代谢与土壤N水平负相关.放牧后牧草生理活动变化与牧草遗传特性、种间竞争、家畜放牧特征、非生物环境等因素密切相关.     

Kinetics and thermodynamics of peroxidase- and laccase-catalyzed oxidation of N-substituted phenothiazines and phenoxazines

N -substituted phenothiazines (PTs) and phenoxazines (POs) catalyzed by fungal Coprinus cinereus peroxidase and Polyporus pinsitus laccase were investigated at pH 4–10. In the case of peroxidase, an apparent bimolecular rate constant (expressed as k _cat/K _m) varied from 1 ×10⁷M⁻¹s⁻¹to 2.6×10⁸M⁻¹s⁻¹ at pH 7.0. The constants for PO oxidation were higher in comparison to PT. pH dependence revealed two or three ionizable groups with pK _a values of 4.9–5.7 and 7.7–9.7 that significantly affected the activity of peroxidase. Single-turnover experiments showed that the limiting step of PT oxidation was reduction of compound II and second-order rate constants were obtained which were consistent with the constants at steady-state conditions. Laccase-catalyzed PT and PO oxidation rates were lower; apparent bimolecular rate constants varied from 1.8×10⁵M⁻¹s⁻¹ to 2.0×10⁷M⁻¹s⁻¹ at pH 5.3. PO constants were higher in comparison to PT, as was the case with peroxidase. The dependence of the apparent bimolecular constants of compound II or copper type 1 reduction, in the case of peroxidase or laccase, respectively, was analyzed in the framework of the Marcus outer-sphere electron-transfer theory. Peroxidase-catalyzed reactions with PT, as well as PO, fitted the same hyperbolic dependence with a maximal oxidation rate of 1.6×10⁸M⁻¹s⁻¹ and a reorganization energy of 0.30 eV. The respective parameters for laccase were 5.0×10⁷M⁻¹s⁻¹ and 0.29 eV. Received: 20 September 1999 / Accepted: 24 February 2000     

Coiled-coil nanomechanics and uncoiling and unfolding of the superhelix and alpha-helices of myosin

The nanomechanical properties of the coiled-coils of myosin are fundamentally important in understanding muscle assembly and contraction. Force spectra of single molecules of double-headed myosin, single-headed myosin, and coiled-coil tail fragments were acquired with an atomic force microscope and displayed characteristic triphasic force-distance responses to stretch: a rise phase (R) and a plateau phase (P) and an exponential phase (E). The R and P phases arise mainly from the stretching of the coiled-coils, with the hinge region being the main contributor to the rise phase at low force. Only the E phase was analyzable by the worm-like chain model of polymer elasticity. Restrained molecular mechanics simulations on an existing x-ray structure of scallop S2 yielded force spectra with either two or three phases, depending on the mode of stretch. It revealed that coiled-coil chains separate completely near the end of the P phase and the stretching of the unfolded chains gives rise to the E phase. Extensive conformational searching yielded a P phase force near 40 pN that agreed well with the experimental value. We suggest that the flexible and elastic S2 region, particularly the hinge region, may undergo force-induced unfolding and extend reversibly during actomyosin powerstroke.     

白术同源四倍体的诱导和鉴定及其与二倍体过氧化物酶的比较

以白术（Atractylodes macrooephala Koidz.）二倍体组培苗为材料,对其四倍体诱导方法进行研究,共获得45个白术同源四倍体株系,为优良株系的选育提供了材料。此外,还分析比较了其中8个白术四倍体株系与二倍体的过氧化物酶同工酶（POD）的酶谱差异,发现四倍体各株系过氧化物酶同工酶谱比二倍体的均多了Rf0.310的谱带,且总过氧化物酶比活力也发生了很大改变,对探讨白术四倍体优良株系的生理生化机理具有一定的参考价值。     

Synthesis of hapten and conjugates of coumestrol and development of immunoassay

3-O-Carboxymethylcoumestrol was prepared as the hapten for immunoassay by a partial alkylation of coumestrol with ethyl chloroacetate in acetone alkalized with potassium carbonate. 3-O-Ethoxycarbonylmethylcoumestrol was separated by column chromatography and finally was hydrolyzed with formic acid. 1H and 13C NMR data (APT, COSY, HMQC, and HMBC) revealed that the reaction was regioselective, as 3-O-ethoxycarboxymethylcoumestrol was the only monosubstituted derivative. The hapten was then conjugated to bovine serum albumin and used for immunization of rabbits. A radioimmunoassay (RIA) system was established based on the polyclonal antiserum and a 125I-labeled hapten-tyrosine methyl ester conjugate as the radioligand. Parameters of the RIA: sensitivity: 12 pg per tube, 50% intercept: 140 pg per tube, working range: 20-4000 pg per tube. The cross-reactivity of a panel isoflavonoid and lignan phytoestrogens was either negligible (e.g. formononetin 0.07%; biochanin A 0.06%) or not detectable at all. The major immunoreactive peak in HPLC fractions from an alfalfa extract had the same retention time as coumestrol standard and represented 94.8% of the signal. The remaining 5.2% of immunoreactivity was distributed between five minor peaks. We conclude that after the validation for particular matrices, the method will be a useful tool for analysis of coumestrol, especially in low volume and low concentration samples.     

Morphology and putative function of the colon and cloaca of marine and freshwater snakes

Among tetrapods, evidence for postrenal modification of the urine by the distal digestive tract (including the colon and cloaca) is highly variable. Birds and bladderless reptiles are of interest because the colon and cloaca represent the only sites from which water and ions can be reclaimed from the urine secreted by the kidney. For animals occupying desiccating environments (e.g., deserts and marine environments), postrenal modification of the urine may directly contribute to the maintenance of hypo‐osmotic body fluids. We compared the morphology and distribution of key proteins in the colon, cloaca, and urogenital ducts of watersnakes from marine (Nerodia clarkii clarkii) and freshwater (Nerodia fasciata) habitats. Specifically, we examined the epithelia of each tissue for evidence of mucus production by examining the distribution of mucopolysaccharides, and for evidence of water/ion regulation by examining the distribution of Na⁺/K⁺‐ATPase (NKA), Na⁺/K⁺/Cl^? cotransporter (NKCC), and aquaporin 3 (AQP3). NKCC localized to the basolateral epithelium of the colon, urodeal sphincter, and proctodeum, consistent with a role in secretion of Na⁺, Cl^?, and K⁺ from the tissue, but NKA was not detected in the colon or any compartment of the cloaca. Interestingly, NKA was detected in the basolateral epithelium of the ureters, suggesting the urothelium may play a role in active ion transport. AQP3 was detected in the ureters and coprodeal complex, consistent with a role in urinary and fecal dehydration or, potentially, in the production of the watery component of the mucus secreted by the coprodeal complex. Since no differences in general cloacal morphology, production of mucus, or the distribution of ion transporters/water channels were detected between the two species, cloacal osmoregulation may either be regulated by proteins not examined in this study or may not be responsible for the differential success of N. c. clarkii and N. fasciata in marine habitats. J. Morphol. 2011. © 2011 Wiley Periodicals, Inc.