谷氨酸钠兴奋尾侧导水管周围灰质腹外侧部的升压反应及其在脑干内的传出通路

实验用乌拉坦麻醉、箭毒化、人工呼吸的大鼠,观察到:(1) 胞体兴奋剂L-谷氨酸钠(Glu)注入尾侧导水管周围灰质腹外侧部(PAG)引起明显的加压反应,(2) 该效应可被双侧延髓头端腹外侧(RVL)加压区内注射酚妥拉明或心得安衰减,但不受阿托品注入RVL影响;表明此升压反应是通过RVL及其内的α-及β-受体实现的。(3) RVL内注入心得安也可衰减电刺激腹侧臂旁核(NPV)的加压作用,却不影响Glu注入NPV的升压效应;结合以往的实验结果,提示尾侧PAG腹外侧部的神经元发出的轴突,可能一方面路过臂旁核直接作用于RVL内的β-受体,另一方面可能在臂旁核内换元,然后作用于RVL内的α-受体,而起升压作用。     

Expression of C4-like photosynthesis in several species of Flaveria

Abstract Photosynthetic metabolism was investigated in leaves of five species of Flaveria (Asteraceac), all previously considered to be C₄ plants. Leaves were exposed to ¹⁴CO₂ for different intervals up to 16s. Extrapolation of ¹⁴C-product curves to zero time indicated that only F. trinervia and F.bidentis assimilated atmospheric CO₂ exclusively through phosphoenolpyruvate carboxylase. The proportion of direct fixation of ¹⁴CO₂ by ribulose-I, 5-bisphosphate carboxylase/oxygenase (Rubisco) ranged from 5 to 10% in leaves of F. australasica. F. palmeri and F. vaginata. Protoplasts of leaf mesophyll and bundle sheath cells were utilized to examine the intercellular compartmentation of principal photosynthetic enzymes. Leaves of F. australasica, F. palmeri and F. vaginata contained 5 to 7% of the leaf's Rubisco activity in the mesophyll cells, while leaves of F. trinervia and F. bidentis contained at most 0.2 to 0.8% of such activity in their mesophyll cells. Thus, F. trinervia and F. bidentis have the complete C₄ syndrome, while F. australasica, F. palmeri and F. vaginata are less advanced, C₄-like species.     

低钾胁迫对不同基因型水稻苗期根系生长和内源激素含量的影响

以2个耐低钾基因型水稻N18、N19和2个低钾敏感基因型水稻N27、N28为材料,采用溶液培养试验,研究低钾胁迫对其苗期根系生长和内源激素含量的影响。结果表明,低钾胁迫下,水稻根长、地上部干重和根干重均降低,但N18和N19显著高于N27和N28。低钾胁迫使4个基因型水稻的根冠比增大,而各基因型之间差异不显著。低钾胁迫下,水稻根中IAA、GA₁和ZR含量均减少,ABA含量增加;N18、N19根中IAA、GA₁和ZR含量都高于N27、N28。此外,低钾胁迫使水稻根中IAA/ABA、ZR/ABA、GA₁/ABA值降低,但N18、N19的上述比值高于N27、N28。     

芽孢杆菌T3菌株对镉胁迫下蒌蒿生理特性和根际微生物的影响

为探讨镉(Cd)胁迫条件下蒌蒿对促生细菌(PGPB)的响应机制,以芽孢杆菌T3(Bacillus sp.)菌株为对象,通过盆栽试验,研究不同Cd处理水平下芽孢杆菌T3菌株对蒌蒿生长、生理、Cd富集转运以及根际微生物的影响。结果表明:(1)在Cd胁迫条件下,芽孢杆菌T3菌株可显著促进蒌蒿地上部、地下部及总干物质的积累,但对株高和根冠比的影响不明显。(2)芽孢杆菌T3菌株能显著促进Cd胁迫条件下蒌蒿对Cd的富集与转运,相比单一Cd胁迫,蒌蒿地上部生物富集系数(BCF)增加了8.3%~29.3%,地下部BCF减少了6.6%~11.1%,同时转运系数(TF)增加了20.8%~38.3%。(3)在Cd胁迫和芽孢杆菌T3菌株的共同作用下,蒌蒿叶绿素a、叶绿素b和总叶绿素含量明显增加。(4)芽孢杆菌T3菌株使Cd胁迫条件下蒌蒿体内丙二醛(MDA)含量显著减少,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性明显增加,可有效抵御由Cd胁迫所产生的氧化伤害。(5)芽孢杆菌T3菌株能显著增加Cd胁迫条件下蒌蒿根际土壤细菌、放线菌数量及微生物总量,可减少蒌蒿根际土壤真菌的数量,但与对照差异不显著。研究表明,在Cd胁迫条件下芽孢杆菌T3菌株对蒌蒿生长、生理和根际土壤微生物环境可产生积极影响,可增强蒌蒿植物对Cd胁迫环境的适应性,从而提高其对Cd的耐受能力。     

大鼠下丘脑弓状核抑制蓝斑神经元放电的机制及其在电针效应中的作用

本工作在清醒箭毒化大鼠人工呼吸条件下进行。实验显示下丘脑弓状核(AR)内微量注射谷氨酸钠(Glut)所兴奋的 AR 神经元可以显著抑制蓝斑(LC)神经元放电。这一效应可被 LC内注射纳洛酮(Nx)或抗β-内啡肽(β-End)血清,以及切断支配 LC 的β-End 能束取消。这些结果提示它主要是通过兴奋β-End 能神经元,使其在 LC 内的轴突末梢释放β-End 而实现的。由于 LC 内单纯注射 Nx 时 LC 神经元放电率无可见变化,似可认为 AR 对 LC 无明显紧张性抑制作用。实验还显示 LC 内注抗β-End 血清后,电针兴奋 LC 的后期效应增加;如在电针的同时向 AR 内注 Glut 则电针兴奋 LC 的后期效应被取消;表明电针过程中有弓状核β-End 能神经元对 LC 的抑制作用参与。但此抑制作用似弱于电针对 LC 的兴奋效应,故只能取消(较弱的)电针的后期效应。不能取消(较强的)电针的早期效应。     

Equilibration of Adenylates by Maize Leaf Adenylate Kinase: Effects of Magnesium on Apparent and True Equilibria

In this study, the effect of magnesium on equilibration of adenylatesby purified maize leaf adenylate kinase (AK) was investigated.The equilibration was expressed in terms of either apparentequilibrium constant, defined as K_app=(ATP_total)(AMP_total)/(ADP_total)²,or true equilibrium constant, defined as K_true=(Mg-ATP)(AMP_free)/(Mg-ADP)(ADP_free).At a fixed concentration of free magnesium (1?8–1?9 mM),the K_app, and K_true were constant at 0?76?0?10 and 6?02?0?75,respectively. On the other hand, at the free magnesium rangeof 0?00l4 to 8?3 mM, the K_app varied from 0?30 to 1?27, whileremained constant at 5?93?0?31. The data indicate that, contraryto previous speculations, leaf AK does not maintain an equilibriumof total adenylates. Rather, the enzyme governs an equilibriumof Mg-ADP, free ADP, Mg-ATP, and free AMP, which are the truesubstrates/products of the AK reaction. Some implications ofthis finding for studies on energy metabolism in plant tissuesare discussed. Key words: Adenylate kinase, adenylate energy charge, adenylates, C₄-photosynthesis, magnesium     

Species Diversity and Floristic Characteristics of Vascular Plants in Nanji Island,Zhejiang Provience

A total of 393 species (sub type included) in 267 genera, 97 families were reported in Nanji Island, the main island of Nanji Islands National Nature Reserve. After eliminating all the cultivated and invasive species, there were still 304 species in 210 genera and 81 families belonging to wild vascular plants; To better understand the floristic characteristics of Nanji, we applied analysis in 3 levels: At family level, the largest families in pteridophyte were ranked as Pteridaceae、Thelypteridaceae、Lygodiaceae、Dryopteridaceae; In seed plants, almost the largest ones were Cosmopolitan, while the small ones dominented the most, quantitatively and proportionately; The characteristic families of seed flora were consisted of Liliaceae、Amaryllidaceae、Urticaceae、Verbenaceae, cause they got high ratio of VFICS/WFIW; At genus level, the Pantropical Distribution (3810%)、the North Temperate Distribution (1630%) and the East Asia distribution (1131%) formed the main part of seed flora; The proportion of the category of temperate distribution and tropical distribution was 6072% and 3928% respectively; Took 6 other sites as reference, through cluster analysis and R/T ratio comparisons, It was proved that Nanji Island were most similar to that of Wuyanling of Zhejiang Provience but showed more tropical affinities; At species level, wild seed plants can also be divided into 9 areal subtypes, The Yangtze River & Southern Proviences sub type dominented at 5390%, following by South China sub type at 2078%. The results showed that Nanji Island had a distinctive transitional characteristics of flora from north to south China with more tropical biological properties, thus the floristic division of Nanji should on the southern margin area of east China.     

贵州啮齿类恙螨初步调查

自1955年以来,我们曾先后在贵州省各地的鼠和松鼠体上采集了一些恙螨。现将部分标本整理,计有10种,其中1种为未曾描述的新种,1 种为我国的新纪录。兹报道如下。 1.地理纤恙螨 Leptotrombidium deliense(Walch,1922) 宿主 (1)黑线姬鼠 Apodemus agrarius ningpoensis