盘叶忍冬和贯月忍冬及其子代生长和光合特性的比较研究

以父本贯月忍冬(Lonicera sempervirens．L) 、母本盘叶忍冬(Lonicera tragophylla Hemsl.) 及其子代台尔曼忍冬(Lonicera×tellmanniana Hort. Späth)为试材，研究了整个生长季3种材料的生长与光合特性。结果显示：子代台尔曼忍冬在花期和单株花序数方面存在显著的杂种优势；3种材料的最大光化学效率（Fv/Fm）差异不显著；父本贯月忍冬的光合速率、实际光化学效率、藤茎长、基茎以及盛花期时的生物量和子代差异不显著，但在实验结束时生物量显著低于子代；母本盘叶忍冬各种指标除Fv/Fm外均显著低于子代，表现出了极弱的生长特性；子代台尔曼忍冬生长期能持续到8月下旬，虽然超中优势（HOMP）明显，但只在单株总叶面积、叶片数和盛花期单株花序数方面表现出了显著的超亲优势。我们认为台尔曼忍冬在观赏效果方面形成杂种优势的主要生理基础不是通常所认为的光合能力的提高，而是在生长前期显著高的总叶面积使子代形成足够多的同化物质，在其内部分配机制的影响下，子代把大量的同化物质用于花芽分化，而在盛花期后，由于子代的生长期较长，以及较强地耐高温胁迫能力，就会源源不断地形成同化物用于花芽分化，而使得子代在花期和观赏效果方面明显优于贯月和盘叶忍冬。因此，在生长早期采取一些增加总叶面积的栽培措施将有助于改善贯月忍冬和盘叶忍冬的生长和观赏效果。

The effect of acute stress on LTP and LTD induction in the hippocampal CA1 region of anesthetized rats at three different ages

Not all experiences are memorized equally well. Especially, some types of stress are unavoidable in daily life and the stress experience can be memorized for life. Previous evidence has showed that synaptic plasticity, such as long-term potentiation (LTP) that may be the major cellular model of the mechanism underlying learning and memory, is influenced by behavioral stress. However, the effect of behavioral stress on age-related synaptic plasticity in-vivo was primarily known. Here we found that the LTP induction in the hippocampal CA1 region of anesthetized rats obviously showed inverted-U shape related to ages (4, 10 and 74 weeks old rats), but low-frequency stimulation was unable to induce reliable long-term depression (LTD) in these animals. Furthermore, acute elevated platform (EP) stress enabled reliable LTD significantly and completely blocked LTP induction at these ages. Importantly, LTD after exposure to acute EP stress showed similar magnitude over these ages. The present results that stress enables LTD but impairs LTP induction at these three ages strengthen a view that stress experience-dependent LTD (SLTD) may underlie stress form of aberrant memories. (C) 2004 Elsevier B.V. All rights reserved.

Effects of gamma-aminobutyric acid, progesterone and ionophore A23187 on acrosome reaction of tree shrew sperm in vitro: examination of acrosome reaction with an improved fluorescence microscopy

A number of acrosome reaction (AR) initiators have been found to be effective in inducing AR of human, laboratory and domestic animal sperm. Using an improved simple fluorescence microscopy, effects of gamma-aminobutyric acid (GABA), progesterone and ionophore A23187 on sperm AR of tree shrew, a useful animal model in biomedical research, have been investigated. Spontaneous AR in 4.92-7.53% of viable sperm was observed. Complete AR in 10.31-18.25% of viable tree shrew sperm was obviously induced by 5 mu M and 10 mu M calcium ionophore A23187, 1 mM GABA, and 5 mu M progesterone, and there were no significant differences between their abilities to initiate complete AR. No significant differences of AR percentages between 1- and 2-h treatments with A23187, progesterone and/or GABA were observed. These results suggested that the responses of tree shrew sperm to these AR initiators are similar to that of human and other mammalian sperm. (C) 1997 Elsevier Science B.V.