Atomic force microscopic observation on substructure of pollen exine inCedrus deodara andMetasequoia glyptostroboides

The substructure of pollen exine inCedrus deodara (Roxb.) Loud. andMetasequoia glyptostroboides Hu et Cheng has been examined with an atomic force microscope (AFM). The results indicate that the exine substructure units containing sporopollenin in two species are similar in shape, which are granular, but slightly different in size. InCedrus the substructure unit of pollen exine appears to be 56–99 nm long and 42–74 nm wide, while inMetasequoia it appears to be 81–118 nm long and 43–98 nm wide. It has been observed that the subunits of pollen exine inCedrus arranged tightly to form short-rod-like or spheroidal pollen exine units, several or more than ten of which formed an island-like structure. There are various spaces among these island-like structures which are interconnected to occupy the entire pollen exine. InMetasequoia, the subunits of pollen exine also arranged tightly with a distribution tendency of cluster of 3–10, however, no obvious boundary exists among these clusters. From our results, it is concluded that there is no tendency of helical arrangement for the subunits of pollen exine inCedrus andMetasequoia, and the results support Southworth’ view that subunits of pollen exine are granular shape in lattice structure.     

宁夏枸杞花粉形态的扫描电镜观察

首次报道了宁夏枸杞３个品种、一个变种的花粉在扫描电镜下的形态特征．结果表明：供试花粉均为小花粉类型，椭圆形，或近球形，三孔沟，等极，表面有夹带二岐分叉的条状纹饰作纵向排列．具不同条状纹饰和条纹表面的不规则细横纹是供试花粉的区别点．花粉的大小和形状，在供试各品种之间也有不同程度的差异     

Pollen Morphology of Artemisia L. and Its Systematic Significance

0　IntroductionThe morphological researches on the pollen grainof Artemisia can be oddly seen in overseas re ports (Woodhouse[1,2], Erdtman[3,4], Ikuse[5], Ska varla and Larson[6], Singh and Joshi[7], Praglows ki[8], Rowley[9] et al). Researchers in…     

中国蓼科花粉萌发孔的平行进化

利用光学显微镜和扫描电镜对蓼科１２ 属１１１ 种的花粉进行了观察和研究,划分出２８ 个花粉类型,对每个类型做了精确的描述和评价;提供了每个花粉类型的重要鉴别特征．根据花粉的萌发孔、外壁结构、外壁纹饰、形状及大小的演化趋势,讨论了各类型花粉的亲缘关系,构建了它们的系统演化路线图谱．该项研究不仅为化石花粉的研究提供了鉴定依据,而且为中国蓼科孢粉地理学的研究提供了理论基础．     

Pollen Morphology of Artemisia L. and Its Systematic Significance

The pollen of 57 species representing 7 sections of Artemisia was examined hy light microscope and scanning microscope for the purpose to elucidate the systematic relationships of the genus. The examination indicates that the pollen grains present high concordance which is characterized by the globular or the appruximate shape. 3-lobed circular from polar view while granular or ellipse sphere from tropical plate with tricolporate structure. The exinc of pollen has an obvious double structure of inner and outer layers (including the tecturn and columnar layers) where the outer is thicker than the inner and the sculpture of exine degenerates into small spinules easily distinguishable from other genera of the Compositae. Based on cxine sculpture, the pollen grains of Artemisia can be divided into two types: Myriantha type and Mongolica type, which possesses 4 subtypes according to the distribution forms of spinulc: (1) Sacrorum subtype, (2) Oligocarpa subtype, (3) Lavandulaefolia subtype. (4) Anomale subtype.     

我国特有植物—永瓣藤花粉形态的研究

卫矛科永瓣藤属(Monimopetlum)特产我国,只有一种,即永瓣藤(M.Chinense Rend.)本文报道了通过光学显微镜、扫描电镜、透射电镜对其花粉外壁进行系统研究的结果。从花粉形状、萌发孔类型以及外壁超微结构看,永瓣藤花粉应是卫矛科(Celastraceae)中的一个独特类型。     

小叶锦鸡儿及其两个近缘种花粉形态种内多态性研究

用扫描电镜在个体水平上研究了小叶锦鸡儿及春两个近缘种１５株植物和同株不同发育时期４朵花蕾中的花粉形态,并用透射电镜观察了观察了柠条锦鸡儿花粉外壁的超微结构。该三种植物花粉粒长球形或长圆球形,具三孔沟,外壁具小穿孔或细网状纹饰;粉形态特征在同一植株上是稳定的,但因个体的不同而明显区别,特别在形状、大小和外壁纹等方面表现出显的种内多态性。     

中国苦苣苔科长蒴苣苔属花粉形态研究

本文对中国苦苣苔科长蒴苣苔属8种花粉形态进行了扫描电镜观察。花粉均具三拟孔沟，形状为近长球形，极面观为三裂圆形，赤道面观为椭圆形，花粉沟相当长且相当窄，内陷，沟膜有颗粒突起。研究表明：长蒴苣苔属各种类花粉在形状和花粉沟等主要特征上具有很好的一致性，但在表面纹饰上有一定的区别。     

Two-headed binding of a processive myosin to F-actin

Myosins are motor proteins in cells. They move along actin by changing shape after making stereospecific interactions with the actin subunits. As these are arranged helically, a succession of steps will follow a helical path. However, if the myosin heads are long enough to span the actin helical repeat (approximately 36 nm), linear motion is possible. Muscle myosin (myosin II) heads are about 16 nm long, which is insufficient to span the repeat. Myosin V, however, has heads of about 31 nm that could span 36 nm and thus allow single two-headed molecules to transport cargo by walking straight. Here we use electron microscopy to show that while working, myosin V spans the helical repeat. The heads are mostly 13 actin subunits apart, with values of 11 or 15 also found. Typically the structure is polar and one head is curved, the other straighter. Single particle processing reveals the polarity of the underlying actin filament, showing that the curved head is the leading one. The shape of the leading head may correspond to the beginning of the working stroke of the motor. We also observe molecules attached by one head in this conformation.     

六种沙蒿花粉形态的比较研究

通过光学显微镜和扫描电镜．观察了蒿属6种沙生半灌木的花粉形态．结果表明，6种沙蒿的花粉形态高度一致,极面观均为三裂圆形，赤道面观为圆形或椭圆形，具三孔沟，外壁纹饰在光镜下为表面颗粒状，在电镜下为排列较疏的刺，刺基外延．     

榆叶梅种内花粉的扫描电镜观察

对11株榆叶梅花粉进行了扫描电镜观察。结果表明,11株榆叶梅花粉的形态、大小与外壁纹饰存在一定的差异,表明榆叶梅花粉的形态出现了分化。     

山东鸭跖草科植物的花粉形态研究

利用扫描电子显微镜,对鸭跖草科3属4种植物的花粉形态进行了观察研究,报道了花粉形态特征,探讨了花粉形态特征在分类学上的意义。结果表明,该科花粉粒大小、形状和表面雕纹可作为属、种的分类依据。     

内蒙古柴胡属植物花粉形态及其分类

本文首次用扫描电镜观察了内蒙古柴胡属７种１１株植物的花粉形态。该属植物花粉形态相对一致，但在花粉粒形状、纹饰细微结构和孔膜等方面有差异。根据形状和孔膜特点本属花粉可分为近菱形，卵形和近长方形等三类；以外壁纹饰特征又可分为皱波状纹饰较明显和不明显两类，后两类与以小总苞片特征所得的类群基本吻合。柴胡属某些种花粉形态在种内有变异现象。     

铁兰属5种植物花粉微形态的扫描电镜观察

在扫描电子显微镜下观察了5种铁兰属植物花粉的微形态,结果表明：铁兰属植物花粉的微形态具有一定的共性,即都具有1个萌发沟,花粉外壁都具网纹纹饰,说明铁兰属植物是自然类群中较进化的类群。根据花粉形状的不同,推测松萝铁兰(Tillandsia usneoides)可能是铁兰属中较原始的种。铁兰属不同种在花粉大小、网孔形状、网孔间距等情况有较大的差异,这些花粉表面微观形态的差异可为种的分类提供依据。     

山东毛茛属植物的花粉形态研究

利用扫描电子显微镜对山东毛茛属（Ranunculus L．）3种植物的花粉形态进行了观察和研究．结果显示该属花粉为长球形,具3沟,外壁具颗粒状刺雕纹．本属花粉粒形状、大小和外壁雕纹的细微结构可以作为种间分类的依据．     

怀地黄不同品种花粉形态的扫描电镜观察

利用扫描电镜观察了14个品种怀地黄[Rehmannia glutinosa f.hueichingens-is(Chan et Sehih)Hsiao]的花粉形态.结果表明:花粉均为单粒花粉,呈长圆形至长矩圆形,大小为40.2~46.9μm,具3个萌发孔,网状纹饰,网眼明显;根据花粉形状可将其分为3类:(1)长方形或近长方形(2)椭圆形或近椭圆形(3)梭形.研究表明,花粉特征,特别是花粉的形态特征,在怀地黄不同品种间具有的可见变异,它们在分类学上的价值应予以关注.     

内蒙古野豌豆属(Vicia L.)植物的花粉形态研究

利用扫描电子显微镜观察了内蒙古境内１３种野豌豆属植物的花粉形态,系统报道了１２种植物的花粉形态．观察结果表明,野豌豆属植物花粉的形状、萌发孔及外壁饰纹等特征在种内是稳定的．此外,利用花粉形态特征,对复合种的分类进行了进一步的探讨．     

中药溪黄草及其药用近缘种的花粉形态

用光学显微镜和扫描电镜对中药溪黄草４种基源植物折花粉形态进行了观察和比较研究。结果表明：光学显微镜下该四种植物的花粉形态相似,赤道面观长球形至扁球形,极面观６裂圆形,具６沟,外壁具粗网状纹饰,而扫描电镜下４种花粉在外壁纹饰、萌发沟等方面存在着明显差异,这些差异可为近缘种的鉴定以及该类生药的鉴定提供依据。     

蓼属蔓蓼组花粉外壁超微结构的研究

花粉壁的构造提供了若干在系统发育上有用的特征 ,其中外壁的层次、结构以及纹饰是基本的。为此 ,本文以花粉壁的内部结构为重点 ,用透射电镜的薄切片技术 ,对广义蓼属蔓蓼组的 4种植物花粉外壁构造的特点进行了观察和研究。结果表明 :外壁结构分化成两个明显的层次 ,即外面的外壁外层以及内面的外壁内层 ,其外壁外层由覆盖层、柱状层和底层组成的。然而由于每一部分发育状况的不同 ,而导致每一种植物花粉的外壁结构具有各自的鉴别特征     

内蒙古岩黄芪属（HedysarumL．）植物花粉形态及其分类

用扫描电镜观察了内蒙古产岩黄芪属８种、２变种植物的花粉形态．该属植物花粉形态相对一致，但在花粉粒形状、纹饰结构和孔膜等方面有差异．根据形状和孔膜特点本属花粉可分为近球形、近长球形、长球形和超长球形及孔膜外突和不外突序类型；以外壁纹饰特征又可分为网状、细网一穿孔状和穿孔状纹饰三类．结合其他分类学特征．对一些种进行了讨论和分类学处理，同时支持建立新变种：戈壁岩黄芪ＨｅｄｙｓａｒｕｍｆｒｕｔｉｃｏｓｕｍＰａｌｌ．ｖａｒ．ｇｏｂｉｃｕｍＹ．Ｚ．Ｚｈａｏｅｔａｌ．．