植物细胞核的凹入和核液泡的形成

核质互作在细胞核中形成膜囊结构首先是在动物细胞中揭示的［１］。对植物细胞超微结构的研究亦发现有类似现象的存在［２—４］。在植物细胞核中形成的膜泡认为有两种形式：一是核被膜向核基质深度凹入,形成细胞质深入细胞核的状态,称之为“假包被（ｐｓｅｕｄｏ－ｉｎｃｌｕｓｉｏｎ）”［２,５］;另一种形式是细胞核内膜或内外双层核膜向核基质深度凹入,并最终脱离核被膜,在核基质中形成囊泡结构,称之为“核液泡（ｎｕｃｌｅａｒｖａｃｕｏｌｅ）”［３,４,６,７］。对细胞核质间通过核被膜在结构上的特殊作用形式缺少像对通过…     

Sustained Food Vacuole Formation by Axenic Paramecium tetraurelia and the Inhibition of Membrane Recycling by Alcian Blue

It is believed that the uptake mechanism of some nutrients by Paramecium tetraurelia primarily involves transport through the cell surface, whereas the uptake of other compounds appears to be restricted to bulk transport during food vacuole (phagosome) formation. In this study, we established that, in axenically grown cells, food vacuole formation occurred at continuous rates over long periods. This information allows quantitation of the volume of media taken up by bulk transport. India ink and latex beads were shown to be inert food vacuole markers and carmine was found to have an initial stimulatory effect on phagosome formation rates. Cultures grown for 3.5 h or longer with the glycocalyx stain Alcian Blue, contained only three phagosomes/cell, whereas cells cultured with the other markers contained 15 phagosomes/cell. Electron microscopy of fecal material that accumulated at the bottom of Alcian Blue-grown cells demonstrated the presence of membranes, suggesting that the vacuolar membrane was eliminated during defecation. Neither cell lysis nor the formation of autophagous vacuoles was detected in Alcian Blue-grown cells, indicating that the stain was not cytotoxic at the concentrations used. Thus it appeared that the binding of Alcian Blue to the digestive vacuole membrane resulted in a loss of the vacuole membranes from the cell which reduced the amount of membranes retrieved and recycled and hence eventually reduced the rate of phagosome formation. Alcian Blue-treated cultures exhibited decreased rate of growth and final density, which is consistent with a decrease in bulk transport of nutrients resulting from reduced membranes of digestive cycle organelles available in the cell.     

陆地棉抗病基因同源序列的克隆与分析

根据已知抗病基因NBS保守区的P-loop和GLPL区设计一对简并引物F1/R1,以7个抗黄萎病陆地棉品种和2个感黄萎病品种的基因组DNA为模板进行PCR扩增.在9个品种中均扩增出500 bp左右的条带.对目的条带进行回收,连接、转化克隆得到350个阳性克隆,进行测序.在8个棉花品种中克隆到74条具有完整开放读码框的棉花RGAs序列.这74条序列共有64种不同的基因型,有10条与其他品种中的RGAs序列相同.用MEGA软件对8个棉花品种的74条RGA序列以及12个已知的抗病基因的NBS区域进行聚类分析,可分为4类;4类RGAs之间的相似性较低,各类之内的RGAs虽然来自不同品种,氨基酸序列的相似度却非常高.推测各大类中相似性较高的序列分别属于同一个基因家族,从位点上说可能处于同一个基因簇.     

Effects of drought on [1-14C]-oleic and [1-14C]-linoleic acid desaturation in cotton leaves

The effects of water stress on [1-¹⁴C]-oleic and [1-¹⁴C]-linoleic acid desaturations were studied in leaves of two varieties of cotton ( Gossypium hirsutum L.), one drought-sensitive (Reba) and the other more resistant (Mocosinho). After 24 h incorporation, [1-¹⁴C]-oleate led to the appearance of linoleate in phospholipids and, additionally, of linolenate in galactolipids. [1-¹⁴C]-Linoleate was desaturated to linolenate only in galactolipid fractions. Water stress markedly inhibited the incorporation of the precursors into the leaf lipids. The two desaturation steps were affected, particularly the transformation of linoleate to linolenate in monogalactosyldiacylglycerol in the drought-sensitive variety of cotton. The metabolic implications of the inhibition of the biosynthesis of C₁₈-polyunsaturated fatty acids are discussed.     

PV技术的计算机处理及其在树木水分关系研究中的应用

ＰＶ技术的计算机处理及其在树木水分关系研究中的应用刘建伟,刘雅荣,王世绩（中国林业科学研究院林业研究所,北京１０００９１）ＣｏｍｐｕｔｅｒＰｒｏｃｅｓｓｉｎｇｏｆＰＶＣｕｒｖｅＡｎａｌｙｓｉｓａｎｄＩｔｓＡｐｐｌｉｃａｔｉｏｎｉｎｔｈｅＲｅｓｅａｒｃ...     

Identification of a novel elite genotype for in vitro culture and genetic transformation of cotton

Hypocotyls of cotton (Gossypium hirsutum L.) cultivars cv. YZ-1, Coker 312 and Coker 201 were inoculated on Murashige and Skoog callus induction medium. YZ-1 exhibited a very high regeneration potential, with 81.9 % of the explants inoculated differentiated into embryogenic callus within 8–10 weeks. During the process of callus maintenance (subculture for 1 to 3 years), the total embryos number in Coker 312 and Coker 201 calli dropped sharply, and the percentage of embryo germination decreased. On the contrary, the callus of YZ-1 consistently maintains a high frequency of plant regeneration after long-time subculture. Transgenic kanamycin-resistant calli of Coker 201 partially lost the ability of somatic embryogenesis and plant regeneration. The stress produced by the transformation procedure slightly affected somatic embryogenesis and plant regeneration of YZ-1, which showed minimum loss of plant regeneration ability.     

Effects of water stress on oxygen, hydrogen and carbon isotope ratios in two species of cotton plants

Abstract. Two cotton species ( Gossypium hirsutum L. cv. SJ-2 and Gossypium barbadence cv. S-5) were grown under irrigated (wet) and non-irrigated (dry) conditions in the same field. Leaf water was enriched in ¹⁸O and deuterium in the dry treatment relative to the wet treatment for both species. Only in plants of S-5 was a similar enrichment observed in leaf cellulose. In both species, the isotopic composition of leaf cellulose must reflect the isotopic composition of the actual water pool involved in cellulose synthesis. Therefore, our observations indicate that one species (SJ-2) can maintain a relative isolation of this water pool from direct evapotranspirational effects. Such plant species will more faithfully record, in the isotopic composition of organic matter, the isotopic composition of ground water. In contrast, the isotopic composition of organic matter in plants such as S-5 could be used as an integrated signal reflecting humidity conditions during growth. Water use efficiency, based on seed-cotton yield and total water applied, correlated linearly with differences in carbon isotopic ratios between species in both the wet and dry treatments and between treatments in each species.     

Nitrate reductase activity,biomass, yield,and quality in cotton in response to nitrogen fertilization

In the production of cotton (Gossypium hirsutum L.), nitrogen fertilization is one of the most costly crop practices, but important to reach high yields. However, high nitrogen (N) content in plants does not always translate into a high fibre production. One way of assessing the efficiency of the N fertilizer is through the enzymatic activity of the nitrate reductase (NR). This is a key enzyme in N assimilation, whose activity is regulated by a number of endogenous and exogenous factors that determine yield. The aim of this study was to assess the effect of N fertilization on yield, fibre quality, biomass, and NR enzymatic activity in vivo in the cotton variety Fiber Max 989. The evaluated application rates were 0, 50, 100, and 150 kg/ha of N, using urea as a source (46% N) in a randomizedblock design with three replicates. At harvest, the maximum yield of seed cotton and the greatest accumulation of total foliar biomass through time was reached after applying 150 kg N/ha. The different N-application rates did not affect the components of cotton-fibre quality. The activity of endogenous NR was greater on plants where 150 kg N/ha were applied. The highest cotton yield and N contents were obtained on these plants. Therefore, the NR activity in vivo could be used as a bioindicator of the N nutritional level in cotton.     

水稻胚乳细胞质膜内陷的超微结构和磷酸酶的细胞化学定位

对生长分化期水稻胚乳细胞的质膜内陷进行了超微结构和磷酸酶的细胞化学研究。结果表明 ,胚乳细胞内的小泡、内质网常与胞间连丝相连 ;质膜形态多变 ,功能活跃 ,由局部起伏的波纹状发展成明显内陷 ,深浅不一 ,多呈袋状 ,袋中包含着大小不一的泡状物 ;有些内陷脱离质膜成为胞质中的囊泡 ,表现出活跃的内吞现象。除细胞间隙中含有圆球状的内含物外 ,在质膜内陷和囊泡中常含有大量的内含物。H ATP酶定位结果显示 ,质膜及其邻近的泡状物周围有酶的分布 ;而酸性磷酸酶定位在液泡、胞间隙和其中的泡状内含物周围 ;在质膜及其内陷形成的囊泡中有G6P酶的分布。这些结果表明胞间隙和质膜内陷在物质的运输中可能起着重要作用     

A Single Herpesvirus Protein Can Mediate Vesicle Formation in the Nuclear Envelope

Herpesviruses assemble capsids in the nucleus and egress by unconventional vesicle-mediated trafficking through the nuclear envelope. Capsids bud at the inner nuclear membrane into the nuclear envelope lumen. The resulting intralumenal vesicles fuse with the outer nuclear membrane, delivering the capsids to the cytoplasm. Two viral proteins are required for vesicle formation, the tail-anchored pUL34 and its soluble interactor, pUL31. Whether cellular proteins are involved is unclear. Using giant unilamellar vesicles, we show that pUL31 and pUL34 are sufficient for membrane budding and scission. pUL34 function can be bypassed by membrane tethering of pUL31, demonstrating that pUL34 is required for pUL31 membrane recruitment but not for membrane remodeling. pUL31 can inwardly deform membranes by oligomerizing on their inner surface to form buds that constrict to vesicles. Therefore, a single viral protein can mediate all events necessary for membrane budding and abscission.     

高等植物共质体区内与区间的电波传递

本文以白花紫露草(Tradescantia flumi—nensis Vel)为材料,运用胞外、胞内微电极及显微注射等方法,对电波在植物体内的传递方式进行了进一步探讨。结果表明,白花紫露革对于伤害性刺激可以产生强烈的电位波动在周身传递。这种电位波动可以被FAA固定液造成的生理障碍阻断;白花紫露草叶片可分为不同的共质体区,在共质体区内,电波传递很快,远高于液相中物质的扩散速度;而在各共质区问,电波传递出现时间上的延迟,与共质体内电波传递速度相差一个数量级,因此,可以推测,在共质体区内电波是以局部电流的方式传递的,而在共质体区问,电波的传递可能有化学介质的参与。     

一个陆地棉bZIP蛋白cDNA的克隆及表达分析

利用PCR筛选方法从陆地棉纤维cDNA文库中筛选到一个全长cDNA序列,命名为GhbZIP。其编码产物长度为645个氨基酸残基,序列中含有两个未知功能的保守区域DUF630和DUF632,而DUF632区中有一个类似碱性亮氨酸拉链基元;此外氨基酸序列中还存在一个富脯氨酸区和一个富苯丙氨酸区,因此该蛋白具有植物碱性亮氨酸拉链蛋白的结构特征。亲水性分析表明,GhbZIP为一个典型的膜蛋白。GhbZIP基因主要是在开花3d之后在胚珠和纤维细胞中表达,这表明该基因可能与棉纤维伸长过程中的基因表达调控有关。     

小叶杨DREB同源基因内SSR的发现及群体结构分析

利用基因特异的POR引物从小叶杨（Populus simonii）经干旱胁迫后构建的cDNA文库中扩增得到长度为671bp的PSDREB cDNA克隆。该基因内部含有完整的且大小为543bp的开放阅读框,可编码181个氨基酸残基。在此基础上,对36株小叶杨基因型个体的DREB基因进行了克隆和序列分析,发现其内部存在以CAC为基本单位的4次（A）、5次（B）、7次（C）、8次（D）、9次（E）、10次（F）和11次（G）7种类型的简单重复序列（SSR）。以该重复序列为扩增对象设计引物,对我国11个省16个群体528株小叶杨进行了群体遗传结构分析。结果表明,在检测群体中各位点等位基因频率大小顺序依次为：D〉C〉F〉E〉A〉G〉B：平均有效等位基因数为3．1670,平均观察和期望杂合度分别为0．4685和0．5315,且在多数群体中存在一定程度的近交效应和显著偏离Hardy-Weinberg平衡：而Ewens-Watterson中立性检验表明,除山西宁武、辽宁朝阳和河南伊川外,其它多数群体均属于中立性选择。研究结果将为利用候选基因内SSR标记来评价林木育种资源的遗传多样性以及保护和利用这些资源提供科学的理论依据。     

减压、低温条件下制样的几种植物液泡图象

样品制作中选用的固定剂不同,在电子显微镜下所得的图象差异甚大。高锰酸钾固定的样品中(Luft 1956,Mollenhauer1959),液泡是一个空泡,核也是一个空泡。用四氧化锇(Palade 1952)和醛类-四氧化锇双固定的样品(Sabatini等1963)核内有物质,但液泡仍是一空泡。所有电子显微技术样品制作都离不开固定、脱水、包埋等过程中化学试剂的反复处理,化学试剂处理细胞会抽去部分细胞内含物;或与细胞某些内含物结合形成络合物。从而     

Changes in secondary metabolites and fiber quality of cotton (Gossypium hirsutum) seed under consecutive water stress and in silico analysis of cellulose synthase and xyloglucan endotransglucosylase

Global warming has led to severe drought conditions. The selection of plant varieties that can withstand drought and produce increased yields are of utmost importance. In the current study, secondary metabolites, seed trait and fiber characteristic of cottonseeds (Gossypium hirsutum) exposed to double and third water stress exposure was investigated. Total phenol and tannin content in W₁S₃₃ increased significantly after third water stress exposure. Accumulation of wax was enhanced in seeds of W₃S₃₃ and W₃S₃₄ that were subjected to third water stress. Fiber quality parameters decreased when cottonseeds were rainfed. High irrigation resulted in fragile and delicate fiber. Seeds grown under 66% FC irrigation saved water and produced seeds that had the potential of producing high quality fibers. In silico analysis was performed on cellulose synthase A (CesA) and xyloglucan endotransglycosylase (XET) enzymes present in Gossypium hirsutum. The intracellular locations of the CesA and XET1 enzymes are the plasma membrane and cell wall, respectively. Proline is conserved in the C-terminal of the CesA enzyme and plays an important role in enzyme functionality. This study provides a better understanding as to the mechanisms by which the plant can tolerate and combat water stress conditions as well as reduce water consumption. In order to grow cotton seeds with desirable morphometric characteristics and optimal fibers under water stress exposure and in dry areas, it is better to use seeds that are irrigated under optimal irrigation conditions, ie 66% FC.     

Retention in Situ and Spectral Analysis of Fluorescent Vacuole Components in Sections of Plant Tissues

The contents of plant vacuoles vary in different organs and with the health of the plant, but little is known of the cell-to-cell distribution of soluble organic compounds within plant tissues. Soluble fluorescent phenolic compounds can be immobilized in plant tissues using an anhydrous freeze-substitution and resin embedment process. The vacuolar fluorescence can be characterized in fluorescence photomicrographs for variations in color and intensity, or more quantitatively with spectra obtained using a microspectrofluorometer. This is demonstrated here in freeze-substituted roots and leaves of soybean. Excitation and emission spectra of individual vacuoles can be compared with spectra of pure compounds to form profiles of the varied phenolic contents of plant vacuoles. Such analyses will add an important anatomical dimension to the study of plant defense and stress responses.     

黄土高原小叶杨与其他树种枯落叶混合分解对土壤性质的影响

将小叶杨分别与其他11个树种枯落叶粉碎混合后进行室内分解培养,分析不同树种枯落叶混合分解对土壤性质的影响及其相互作用.结果表明:12个树种枯落叶单独混土分解均明显提高了土壤脲酶、脱氢酶、磷酸酶活性和有机质、碱解N含量,但对土壤速效P含量和土壤阳离子交换量(CEC)的影响差异较大,其中柠条和紫穗槐枯落叶改善土壤性质的效果明显.小叶杨分别与油松、侧柏、刺槐、白榆枯落叶混合分解,对土壤微生物数量的影响存在相互促进作用;小叶杨分别与侧柏、柠条枯落叶混合分解对土壤有机质、速效P、速效K含量和CEC的影响存在相互促进作用,但对土壤大部分酶活性的影响却存在相互抑制作用;小叶杨与落叶松枯落叶混合分解对土壤多数酶活性和养分含量的影响存在相互促进作用,而与樟子松枯落叶混合分解时则有抑制作用.总体上,小叶杨分别与白榆、油松、落叶松和刺槐枯落叶混合分解可促进土壤性质的改善,而与侧柏、柠条、樟子松、沙棘和紫穗槐枯落叶混合分解时则相互抑制.     

Natural deuterium and oxygen-18 enrichment in leaf water of cotton plants grown under wet and dry conditions: evidence for water compartmentation and its dynamics

Abstract. Significant differences in leaf water oxygen and hydrogen isotopic composition were observed between cotton plants grown under wet and dry conditions. The magnitude of the differences could be fully explained by the conventional model that describes the isotopic composition of an evaporating water pool under steady state conditions. The results indicate that leaf water isotopic composition is strongly influenced by transpiration rate via its effects on relative humidity adjacent to the leaf surface and on the isotopic composition of the air moisture. Our application of the model, however, provides evidence that leaf water must consist of a mixture of several isotopically distinct pools. These pools are suggested to reside in the symplast, in the cell walls and intercellular spaces and in the veins. A model is proposed suggesting that only the water residing in the cell walls and the intercellular spaces (the transpiration pool) interacts directly with the external environment. The large symplastic pool responds to the external environment to a limited extent via its relatively slow exchange with water in the transpiration pool. It is likely that the isotopic composition of water in the symplastic pool is strongly buffered against shortterm environmental variations, a possibility that would have important implications for the isotopic conditions under which organic matter biosynthesis occurs.