蕨类植物分株紫萁精子发生过程中生毛体和多层结构的超微结构

应用电镜技术对蕨类植物分株紫萁(Osmunda cinnamomea L. var.asiatica Fernald)精子发育过程中的生毛体和多层结构的超微结构进行了研究.生毛体在幼精子细胞中出现,正在分化的生毛体略呈球状,球状体的中央由一团染色深的颗粒状物质构成,外围分化出若干柱状体.已分化的生毛体由柱状体分散或辐射状排列构成,呈球状,球体中心不含染色深的物质.多层结构位于精子细胞内的基体和巨大线粒体之间,刚形成时仅由片层构成,片层相互平行排列形成片层带.多层结构在分化中期由微管带、片层带和蚀斑三层构成.多层结构在分化末期又形成附属微管带、嗜锇冠和嗜锇层.微管带从多层结构长出,沿细胞核的表面伸展,并与核膜之间形成复合结构.基体由柱状体转变而成,它向两端生长,在远端产生鞭毛的轴丝,在近轴端形成楔状结构.本文首次详细阐明了原始薄囊蕨分株紫萁生毛体和多层结构发育的超微结构特点,并与其他蕨类进行了比较,发现其片层带出现在微管带形成之前.     

分株紫萁卵发生的超微结构

用透射电镜对蕨类植物分枝紫萁(Osmunda cinnamamae L. var. asiatica Fernald)卵发牛进行了超微结构的研究。卵发生过程中,许多泡囊不仅移向细胞周围,而且在细胞质膜内排为一列,并通过胞吐作用聚集在细胞质膜外,它们释放或分泌嗜锇物质。观察到少数泡囊内含片层状结构的嗜饿物质紧贴于细胞质膜,似乎将其冲破。与此同时,在卵细胞和颈卵器壁之问形成分离腔,其宽度大于以往报道的真蕨类,在卵细胞质膜外出现额外的卵膜,其宽度大于蕨属和鳞毛蕨属。造粉体被大型常呈三角状半圆形或近椭圆形的淀粉粒所充满,当卵成熟时逐渐减少。核大型平扁状,核内出现2-3对平行的双层膜,紧贴核膜。未发现核外突。线粒体一度似不发育,最后恢复正常。     

分株紫萁卵发生的超微结构

用透射电镜对蕨类植物分枝紫其(Osmunda cinnamamae L. var.asiatica Fernald)卵发生进行了超微结构的研究.卵发生过程中,许多泡囊不仅移向细胞周围,而且在细胞质膜内排为一列,并通过胞吐作用聚集在细胞质膜外,它们释放或分泌嗜锇物质.观察到少数泡囊内含片层状结构的嗜饿物质紧贴于细胞质膜,似乎将其冲破.与此同时,在卵细胞和颈卵器壁之间形成分离腔,其宽度大于以往报道的真蕨类,在卵细胞质膜外出现额外的卵膜,其宽度大于蕨属和鳞毛蕨属.造粉体被大型常呈三角状半圆形或近椭圆形的淀粉粒所充满,当卵成熟时逐渐减少.核大型平扁状,核内出现2~3对平行的双层膜,紧贴核膜.未发现核外突.线粒体一度似不发育,最后恢复正常.     

蕨类植物桂皮紫萁颈卵器和精子器形态和发育的研究

利用扫描电镜技术和树脂切片技术对蕨类植物桂皮紫萁（Osmunda cinnamomeaL.var.asiatica Fernald)的颈卵器和精子器的形态和发育进行了细致的研究。颈卵器发生于雌配子体的腹面,颈部由4列壁细胞构成,6-7个细胞高,内部含有颈沟细胞,腹沟细胞和卵细胞,卵细胞在整个发育过程中,造粉体和囊泡最为显著,颈卵器内的卵细胞成熟时产生卵膜和分离腔。精子器发生于雄配子体的边缘及腹面,由7-8个壁细胞螺旋状围绕而成,壁细胞内为产精组织,精子成熟时精子器盖细胞开裂释放出游动精子。     

海金沙精细胞中生毛体发育及多层结构起源的超微结构研究

蕨类植物海金沙（LygodiumJaponicum（Thunb．）Sw．）的游动精子发育过程中,生毛体在精母细胞的细胞质中出现,它是直径为0．5－0．6μm的椭球体,其结构紧密,由辐射排列的具轮辐结构的管状亚单位和无定形基质组成。大量微管从生毛体伸向细胞质。随着精细胞的发育,生毛体结构变得松散,亚单位分化形成的中心粒彼此分开扩散到外围,中心为无定形物质。伴随着中心粒的分化,多层结构出现,一端与无定形基质相连。多层结构由外侧的微管带及内侧的片层组成,形成后与一线粒体相连,移向靠近核的位置,并正对着核上出现凹点。研究发现在精原细胞后期出现一团絮状结构,为无定形基质,其中有深染色的小管状结构分布,同时可见微管从絮状结构边缘伸出,这一絮状结构可能与生毛体的产生有一定的关系。     

海金沙精细胸中生毛体发育及多层细胞起源的超微结构研究

蕨类植物海金沙（Ｌｙｇｏｄｉｕｍ ｊｏｐｏｎｉｃｕｍ （Ｔｈｕｎｂ．）Ｓｗ．）的游动精子发育过程中,生毛体在精母细胞质中出现,它是直径为０．５～０．６μｍ的椭球,其结构紧密,由辐射排列的具轮辐结构的管状亚单位和无定形基质组成。大量微管从生毛体伸向细胞质。随着精细胞的发育,生毛体细胞变得松散,亚单位分化形成的中心粒彼此分开矿散到外围,中心为无定形物质。伴随着中心粒的分化,多层结构出现,一端与无定形基     

天麻消化紫萁小菇及蜜环菌过程中细胞超微结构变化的研究

本文对天麻种子消化入侵的紫萁小菇菌丝及营养繁殖茎消化蜜环菌过程中,细胞超微结构的变化进行了研究。观察结果表明:紫萁小菇侵入种胚后,染菌胚细胞的细胞器逐渐消失,其细胞质产生囊状体起消化菌丝的作用,存在于胚细胞中的紫萁小菇菌丝有脱壁或失去细胞质成为空腔等变化;种子萌发形成的原球茎消化紫萁小菇的方式同胚萌发阶段类同。蜜环菌侵入原球茎分化的营养繁殖茎后,皮层细胞产生消化酶类颗粒或囊状体包围并分解蜜环菌菌丝;被皮层细胞消化的菌丝残物或部分菌丝进入皮层内面的大型细胞,此时大型细胞的代谢功能显著增强,该细胞中的各种水解酶颗粒及液泡等完成对菌体物质的最终同化。紫萁小菇及蜜环菌先后在天麻有性繁殖和无性繁殖阶段侵染供给其营养,但菌丝被消化过程中的细胞形态变化、被消化方式不完全一致。     

施氮量和株行距配置对鲜食糯玉米群体冠层结构和产量的影响

采取同一密度不同株行距配置和不同施氮量的试验处理,分析栽培措施和施氮量对糯玉米冠层的SPAD值、叶面积指数(LAI)、光合势、茎叶倾角、叶向值、冠层PAR、冠层开度、产量及产量构成要素的影响。结果表明：在同一密度同一行距条件下,冠层SPAD值、叶向值、PAR随着施氮量增加而增加,各处理间差异显著,而叶倾角随着施氮量增加而减小;不同施氮量对冠层开度影响不大,差异不显著,而对糯玉米产量影响差异显著。在授粉后12～18 d,行距70 cm,施氮量为N3,叶面积指数达最大,光合势最强,且较其它生育期差异明显。     

Density affects gametophyte growth and sexual expression of Osmunda cinnamomea (Osmundaceae: Pteridophyta)

BACKGROUND AND AIMS: To understand how gametophyte densities affect the sexual expression and sizes of Osmunda cinnamomea and to provide information on the density of growth needed to favour successful reproduction, fresh spores were sown at various densities and subsequent gametophyte growth was studied. METHODS: Spores were sown and cultured in the laboratory. Subsequent gameophytes at different population densities were sampled and their sexual expression and sizes were recorded. KEY RESULTS: One-year-old multispore cultures of the fern O. cinnamomea demonstrated that population density affected gametophyte growth and sexual expression. As density increased, gametophytes became significantly smaller and more slender. Female and asexual gametophytes dominated in populations of low and high densities, respectively. At intermediate population densities, hermaphroditic and male gametophytes were dominant. Female gametophytes were larger than gametophytes of all other types. Hermaphroditic gametophytes were larger than male gametophytes, which were larger than asexual gametophytes. Large gametophytes were wide-cordate, whereas smaller ones tended to be narrow-spathulate. CONCLUSIONS: Gametophyte size of O. cinnamomea is negatively related to the population density, which significantly affects gametophytes' sexual expression. The presence of unisexual and bisexual gametophytes at intermediate densities indicates that both intergametophytic and intragametophytic selfing may occur.     

兰属春剑叶艺突变体叶片结构的研究

以兰属春剑(Cymbidium tortisepalum Fukuy.var.longibracteatum)叶色突变体‘隆昌素’及其亲本为材料,采用石蜡切片、扫描电镜及透射电镜对叶片的组织结构、扫描结构和超微结构进行了观察。结果显示,春剑叶色突变体叶片的表皮厚度和叶肉细胞面积均大于亲本,但导管数量少于亲本;叶片上、下表皮纹饰与亲本具有明显差异;气孔密度和面积均小于亲本,且气孔闭合度较大,占总气孔数的56%;突变体的叶绿体呈高密度的囊泡状结构,内部严重解体,体积较小的嗜锇滴聚集分布,无基粒片层,无淀粉粒。本研究表明经组培诱变的春剑叶色突变体的叶片结构与亲本存在明显差异。     

Ultrastructure of Euglena anabaena var. minor (Euglenophyceae)

The freshwater green euglenoid Euglena anabaena var. minor has a pellicle with groove‐ridge articulation, a chloroplast with pyrenoids doubly sheathed by two paramylon caps, and a nucleus with permanently condensed chromosomes and nucleolus. The flagellar apparatus basically resembles that of Euglena. The dorsal root (DR) originates at the dorsal basal body of the emergent flagellum, while both the intermediate root (IR) and ventral root (VR) originate at the ventral basal body of the non‐emergent flagellum. The cytoplasmic pocket is associated with the ventral root/ reinforcing microtubular band. However, ultrastructural characterization of E. anabaena var. minor shows the pocket to consist of five to seven microtubules, and flagellar roots with microtubule configuration of 3–4–6 in the DR‐IR‐VR. The dorsal band microtubules pair at the reservoir‐canal transition level. The doublet microtubules are formed into triplets and doublets at the lower canal level and then make pellicular microtubules at the upper canal level.     

Ultrastructure of trichoblasts in the red alga Osmundea spectabilis var. spectabilis (Rhodomelaceae,Ceramiales)

The apex of the tetrasporangial branches of Osmundea spectabilis var. spectabilis (= Laurencia spectabilis var. spectabilis) exhibits cavities in which tufts of multicellular trichoblasts occur. Trichoblast development in Osmundea spectabilis var. spectabilis begins with the differentiation of an epidermal cell within the crypt. This cell differentiates into a trichoblast mother cell (TMC). The TMC divides to form a two-celled incipient trichoblast. Successive periclinal divisions of the apical cell of the young trichoblast result in the formation of a multicellular developing trichoblast. With the exception of the apical cell all trichoblast cells are at the same developmental stage. They possess a large nucleus, abundant plastids with peripheral and some internal thylakoids and dictyosomes. Daughter chloroplasts result from one constriction or multiple fission of a single chloroplast. Dictyosomal cisternae and mucilage sacs contribute material to wall formation. Each differentiating trichoblast cell is surrounded by a bi-layered wall. The outer wall layer represents the trichoblast mother cell wall and the inner wall layer is the trichoblast cell wall. Mature trichoblast cells have thin walls, probably as a consequence of mucilage extrusion, the most likely function of trichoblasts in Osmundea.     

An Ultrastructural Study of the Development of Blepharoplast and the Origin of Multilayered Structure in the Sperm of Lygodium japonicum

The blepharoplast, an elliptical, compact spherical body ranging 0.5～0.6 /μm in diameter, appears in the cytoplasm of the sperm mother cell during the sperm development of Lygodium japonicum (Thunb.) Sw. It consists of cartwheel tubular subunits arranged in radiant pattern and amorphous material. Numerous microtubules extended from the blepharoplast into cytoplasm. In the process of sperm cell development, the blepharoplast became loose, and the centrioles originated from the subunits separated from each other and dispersed towards the surface, with the amorphous material in the center. Accompanying the differentiation of the centrioles, muhilayered structure with the spline ( i. e. microtubular band) and lamella strata came into existence, with one end attaching to the amorphous material in the center. Then the muhilayered structure (MIS) associated with a mitochondrion and moved towards the nucleus, and a dent facing the MIS is formed in the nucleus. A cotton-like structure consisting of amorphous material and dardyed small tubular structure appeard in late stage of spermatogenesis. Microtubules were seen protruding from the surface of the cotton-like structure. It is suggested that this structure might be relevant to the origin of the blepharoplast.     

五种紫萁属植物的核型分析

研究了5种紫萁属Osmunda植物的核形态学特征, 其间期核属于复杂染色中心型, 有丝分裂前期染色体为中间型, 对有丝分裂前期染色体的动态变化过程和在细胞核内的自然排布情况进行了观察。核型公式为: 粗齿紫萁O. banksiifolia (Presl) Kuhn, 2n=4sm+10st+26t+4T; 紫萁O. japonica Thunb., 2n=2sm+8st+32t(2SAT)+2T;华南紫萁O. vachellii Hook., 2n=4sm+8st+28t+4T; 狭叶紫萁O. angustifolia Ching ex Ching &; Ch. H. Wang, 2n=2sm+4st+34t+4T; 粤紫萁O. mildei C. Chr., 2n=2sm+6st+33t+3T。所有染色体臂比均大于2, 核型类型均为4A, 后3种染色体为首次报道, 且对5种紫萁属植物的核型变异及演化关系进行了讨论, 推测Plenasium亚属3种紫萁属植物中粗齿紫萁核型类型最原始, 狭叶紫萁最进化, 其地理分布与核型不对称性有关联, 粤紫萁可能为一自然种间杂种。     

Evaluation of morphological and molecular variation in Plantago asiatica var. densiuscula, with special reference to the systematic treatment of Plantago asiatica var. yakusimensis

Morphological and molecular variations in Plantago asiatica L. var. densiuscula Pilg. were analyzed to evaluate the genetic basis for recognizing the dwarf variety P. asiatica var. yakusimensis (Masam.) Ohwi. Considerable variation in the leaf size of P. asiatica var. densiuscula was observed, and no morphological discontinuities were found between the dwarf types of P. asiatica var. densiuscula and P. asiatica var. yakusimensis. Morphological analysis of plants grown under standardized conditions revealed that both environmental plasticity and genetic differentiation contributed to the dwarfisms. Molecular phylogenetic analysis of rDNA internal transcribed spacer (ITS) regions and the SUC1 locus encoding a sucrose transporter revealed that P. asiatica var. yakusimensis was genetically unique although the differentiation level was low. From the above results, we concluded that P. asiatica var. yakusimensis should be reduced to a form of P. asiatica var. densiuscula. Furthermore, the geographic distribution of the SUC1 genotype suggested multiple origins of dwarves, and possible hypotheses for the origins of dwarves are discussed.