脓青素对光抑制条件下菠菜叶绿体的保护作用

在有氧条件下,脓青素可以缓解强光对菠菜叶绿体电子传递的抑制作用。加入解联剂尼日利亚菌素消除跨膜质子梯度会加剧叶绿体的光抑制,但脓青素的保护作用并不消失。脓青素对光系统Ⅰ与光系统Ⅱ均表现出保护作用,但对ＰＳⅡ的保护在光抑制初期较明显;在厌氧条件下,脓青素加剧叶绿体的光抑制,引起ＤＣＩＰ光还原与水到ｐ－ＢＱ电子传递活力的降低。推测脓青素可能通过促进细胞色素ｂ５５９介导的ＰＳⅡ循环电子传递,减轻了叶绿体的光抑制。     

海甘蓝种子成熟过程中脂肪酸含量以及脱落酸和山梨醇的效应

海甘蓝种子在成熟过程中,棕榈酸、硬脂酸和亚麻酸的含量不断下降,而二十碳烯酸和芥酸的含量呈上升趋势。选用开花后２５～２７ｄ的海甘蓝幼胚分别在含不同浓度的ＡＢＡ或高渗透剂的培养基中培养１～３ｄ,发现其各种脂肪酸的变化趋势和种子自然成熟过程中脂肪酸的变化相似,说明ＡＢＡ或高渗透剂可能是种子成熟过程中各种脂肪酸合成和相互转化所需的条件。     

水稻蜡质基因5＇上游区缺失对基因表达的影响

为研究水稻蜡质基因（ｗａｘｙ）５＇上游调控区中存在的顺式作用元件,我们将水稻ｗａｘｙ基因翻译起始声、（ＡＴＧ）５＇上游３．４ｋｂ（－２１１８～＋１２９１ｂＰ）片段经外切核酸酶ＥｘｏⅢ部分酶解,得到一系列５＇端缺失的片段。将这些缺失片段分别与ｇｕｓ基因编码区连接,构建成融合质粒,经ＰＥＧ介导引入水稻原生质体,２６℃培养４８ｈ后,定量测定ＧＵＳ酶活力,并以同时导入的由３５Ｓ启动子指导的荧光素酶（ＬＵＣ）基因表达的酶活力作为内对照。结果表明,ＧＵＳ酶活性随５’上游调控区长度的减少而逐渐减弱。由─８６１ｂｐ缺失至─６４０ｂＰ时,ｇｕｓ基因表达水平有较明显的降低,推测在该区域中可能存在一个顺式作用元件区。     

从吸收光谱的变化看H2O2对豆血红蛋白的定位损伤

豆血红蛋白（Ｌｂ）是一种含铁的蛋白质,在大豆（Ｇｌｙｃｉｎｅｍａｘ）的根瘤中含量很。从新鲜根瘤中提取制备的氧合豆血红蛋白（ＬｂＯ２,含二价铁的蛋白质）是Ｌｂ的活性形式。ＬｂＯ２在可见光区５７７ｎｍ和５４０ｎｍ有吸收峰,这两个峰与ＬｂＯ２中血红素（铁卟啉）的结构密切相关;另外,ＬｂＯ２在紫外区２８０ｎｍ处还有一个吸收峰,此峰与珠蛋白（ＬｂＯ２的蛋白质部分）的构象有关．ＬｂＯ２在一定浓度的Ｈ２Ｏ２作用下,可见光的特异吸收变化迅速,而紫外吸收相对稳定,因而推测Ｈ２Ｏ２对ＬｂＯ２的损伤是有着固定的位点,这个位点是在含二价铁的卟啉环上,而不在珠蛋白中．     

Interaction of synthetic peptide corresponding to signal sequence of glucitol permease of Escherichia Coli and its analogue with liposomes

The N-terminal signal sequence of glucitol pcrmease of Escherichia Coli (Gut22) and its analogue (Gut22Ana) were synthesized. The analogue had a Pro residue substituting for the His at the 7th position of Gut22 and a Val residue substituting for the Glu at the 10th position. The intrinsic fluorescence emission spectra indicated that the binding of Gut22 with lipid bilayer was much stronger than that of Gut22Ana. The leakage experiments with calcein-loaded liposomes showed that Gut22 strongly perturbed lipid bilayers while Gut22Ana did not. The apparent partition constant of Gut22 for partitioning into phosphatidylserine/phosphatidylcholine bilayers was measured; the effect of membrane potential on the interaction of Gut22 with lipid bilayers was studied and the conformation changes of Gut22 and Gut22Ana upon interacting with liposomes were studied by the method of circular dichroism analysis.     

厉螨科－新属及二新种（蜱螨亚纲：革螨股）

本文记述厉螨科一新属,邓厉螨属Ｔｅｎｇｉｌａｅｌａｐｓｇｅｎ．ｎｏｖ,其主要特征;角化较强,体毛壮,背毛２９对;颚角粗钝,具纵裂;头盖尖角形;胸板六角形,各角均尖突;殖腹板毛１对;各足股、膝节上均具长毛、模式种为天牛邓厉螨,新种Ｔｅｎｇｉｌａｅｌａｐｓｃｅｒａｍｂｙｃｉｕｓｓｐ．ｎｏｖ。另一新种为副单阳厉螨ＡｎｄｒｏｌａｅｌａｐｓＰａｒａｓｉｎｇｕｌａｒｉｓｓｐ．ｎｏｖ。模式标本均采自云南省的甲虫体上。     

中国土厉螨属一新种（蜱螨亚纲：厉螨科）

本文记述中国土厉螨属１新种,王氏土厉螨Ｏｌｏｌａｅｌｅｐｓｗａｎｇｉ,ｓｐ．ｎｏｖ,新种的模式标本保存在宁夏回族自治区地方病防治所。     

Temporal and spatial variations in the oxygen-18 content of leaf water in different plant species

Temporal variations in the δ¹⁸ oxygen (δ¹⁸O) content of water transpired by leaves during a simulated diurnal cycle fluctuated around the δ¹⁸O content of the source water. Reconstructed variations in the δ¹⁸O values of leaf water differed markedly from those predicted by conventional models. Even when transpiring leaves were maintained under constant conditions for at least 3 h, strict isotopic steady-state conditions of leaf water (equality of the ¹⁸O/¹⁶O ratios in the input and transpired water) were rarely attained in a variety of plant species (Citrus reticu-lata, Citrus paradisi, Gossypium hirsutum, Helianthus annuns, Musa musaceae and Nicotinia tabacum). Isotopic analysis of water transpired by leaves indicated that leaves approach the isotopic steady state in two stages. The first stage takes 10 to 35 min (with a rate of change of about 3–3%h^?1), while in the second stage further approach to the isotopic steady state is asymptotic (with a rate of change of about 0–4% h^?1), and under conditions of low transpiration leaves can last for many hours. Substantial spatial isotopic heterogeneity was maintained even when leaves were at or near isotopic steady state. An underlying pattern in this isotopic heterogeneity is often discerned with increasing ¹⁸O/¹⁶O ratios from base to tip, and from the centre to the edges of the leaves. It is also shown that tissue water along these spatial isotopic gradients, as well as the average leaf water, can have ¹⁸O/¹⁶O ratios both lower and higher than those predicted by the conventional Craig and Gordon model. We concluded, first, that at any given time during the diurnal cycle of relative humidity the attainment of an isotopic steady state in leaf water cannot be assumed a priori and, secondly, that the isotopic enrichment pattern of leaf water reflects gradual enrichment along the water-flow pathway (e.g. as in a string of pools), rather than a single-step enrichment from source water, as is normally assumed.     

西藏厚厉螨属一新种和毛绥螨属一新种(蜱螨亚纲:厚厉螨科,裂胸螨科)

本文报道革螨二新种,西藏厚厉螨Pachylaelapsxizangensissp．nov．和亚东毛绥螨Lasioseiusyadongensissp．nov,1985年采自西藏亚东。