The structure of colleters in several species of Simira (Rubiaceae)

BACKGROUND AND AIMS: Colleters are secretory structures consisting of a parenchymatic middle axis surrounded by a layer of palisade-like epidermal cells. Colleters occur in a large number of rubiaceous species. Their function is to protect the developing shoot apex. They are also taxonomically useful in the Rubiaceae. This study characterized the structure of the colleters of Simira glaziovii, S. pikia and S. rubra and the biochemistry of secretions in S. glaziovii. METHODS: Stipules of the shoot apices of the three species studied were collected at Barragem de Saracuruna, in Rio de Janeiro state, Brazil. The samples were fixed according to the usual methods for light and electron microscopy. Secretion stipules of S. glaziovii were washed with 0.1 m Tris-HCl plus 0.1 %Triton X-100 to extract proteins and carbohydrates. KEY RESULTS: Colleters in these species are located at the base of the stipule. Each species shows a different pattern of distribution. They form as emergentia from the stipules. Simira glaziovii was different from the other two species because it exhibited vascular traces. The epidermal cells of colleters have dense cytoplasm, nuclei, small vacuoles, endoplasmic reticulum, Golgi apparatus, mitochondria and extraplasmic spaces if they are secretory. The outer cell wall of the mature colleters differs from the outer cell wall of stipule cells and immature colleters. Both carbohydrates and proteins were found in secretions from the stipules of S. glaziovii. CONCLUSIONS: Few ultrastructural differences were noted among the three species. These secretory structures not only protect the shoot apex, but also have taxonomic importance below the genus level.     

ULTRASTRUCTURE OF ACTIVE AND RESTING COLONIES OF BOTRYOCOCCUS BRAUNII (CHLOROPHYCEAE)1

The ultrastructure of resting state colonies of Botryococcus braunii Kützing from two localities is compared to active state colonies maintained in the laboratory. Qualitative hydrocarbon analyses confirmed the physiological status of each sample according to the precedent in the literature; resting state colonies contained botryococcenes, while active state colonies contained a predominance of straight-chain olefins. The ultrastructure of resting and active state colonies is fundamentally similar. The chloroplast of resting state cells contains fewer thylakoids and larger relative numbers of plastoglobuli than the chloroplast of active state cells maintained under favorable growth conditions. Previously undescribed phenomena include the cytochemical demonstration of polyphosphate bodies microbody-like organelles and ER-ribosomal-mitochondrial complexes. Attempts to elicit the transition of active to resting state colonies utilizing different light intensities and/or nitrogen deficient media were unsuccessful. Instead, these experiments induced the formation of yellow or whitish-brown senescent colonies which always contained a predominance of olefins. Senescent cells contain reduced, peripherally displaced organelles. Most of the cytoplasm is occupied by vacuoles and lipid (probably hydrocarbon) inclusions. Morphologically identifiable polyphosphate bodies are usually small or absent. Observations pertinent to the mechanism of hydrocarbon secretion were in basic agreement with previously published information. The outer cell wall, or trilamellar structure (TLS), was recently as the primary site of hydrocarbon accumulation and production. The role of the TLS in hydrocarbon biosynthesis, however, should be cautiously regarded without additional evidence.     

Colleters in Bathysa cuspidata (Rubiaceae): Development,ultrastructure and chemical composition of the secretion

This paper describes the development of colleters of Bathysa cuspidata, Rubiaceae, considering anatomical, histochemical and ultrastructural aspects and going from first differentiation stages until senescence. Further, the chemical composition of the secretion is investigated. The samples were prepared according to the usual techniques for light microscopy and scanning and transmission electron microscopy. Electrophoresis and thin layer chromatography (TLC) were used to confirm the results obtained in the histochemical tests. The colleters occur at the ventral surface of the stipules which protect the leaf primordia as well as the shoot meristem. The origin of the colleters is mixed, involving protoderm and ground meristem. The Bathysa colleters are of the standard type or are bifurcated; this latter type is documented here for the first time for Rubiaceae. Colleter secretion is a mucilage rich in protein, as determined by histochemical tests and confirmed by chemical analysis. Phenolic compounds and terpenes were detected only in the colleters themselves, but not in the secretion. The epithelial cells present conspicuous nuclei and nucleoli and the cytoplasm is rich in dictyosomes, endoplasmic reticulum, mitochondria, vesicles and small vacuoles with a fibrillar content. The accumulation of phenolic compounds and terpenes, the formation of a large central vacuole, the increase of the intercellular and subcuticular spaces occupied by the secretion and, finally, the darkening and the wilting of the colleters characterize the senescence of these structures. The secretion process of the colleters of B. cuspidata suggests a process of programmed cell death.     

Functional utrastructure of Genlisea (Lentibulariaceae) digestive hairs

BACKGROUND AND AIMS: Digestive structures of carnivorous plants produce external digestive enzymes, and play the main role in absorption. In Lentibulariaceae, the ultrastructure of digestive hairs has been examined in some detail in Pinguicula and Utricularia, but the sessile digestive hairs of Genlisea have received very little attention so far. The aim of this study was to fill this gap by expanding their morphological, anatomical and histochemical characterization. METHODS: Several imaging techniques were used, including light, confocal and electron microscopy, to reveal the structure and function of the secretory hairs of Genlisea traps. This report demonstrates the application of cryo-SEM for fast imaging of whole, physically fixed plant secretory structures. KEY RESULTS AND CONCLUSION: The concentration of digestive hairs along vascular bundles in subgenus Genlisea is a primitive feature, indicating its basal position within the genus. Digestive hairs of Genlisea consist of three compartments with different ultrastructure and function. In subgenus Tayloria the terminal hair cells are transfer cells, but not in species of subgenus Genlisea. A digestive pool of viscous fluid occurs in Genlisea traps. In spite of their similar architecture, the digestive-absorptive hairs of Lentibulariaceae feature differences in morphology and ultrastructure.     

火炬树分泌道的发育解剖学研究

本文报道了火炬树分泌道的结构、分布和发育。火炬树的分泌道是由一层分泌细胞及其外侧1—5层薄壁组织细胞组成的鞘细胞所包围。分泌道主要分布于根、茎、叶、花和果实的维管束的韧皮部内,此外,在茎的髓部也存在散生的分泌道。各类器官中的分泌道都以裂生方式发育;营养器官中的分泌道先于维管分子分化,生殖器官中的则后于维管分子的分化。     

热带药用植物根际放线菌的分离、鉴定及生物活性分析

从海南热带植物园采集12种药用植物的根际土样,采用选择性分离方法,分离得到400株根际放线菌。使用5种活性筛选模型对分离菌株进行生物活性评价,154株放线菌在一个或多个活性筛选模型中显示为阳性,菌株初筛阳性率达38.5%;根据菌株形态特征并结合代谢产物的生物活性,从中挑选出28株菌进行16S rRNA基因序列分析,发现其分属于链霉菌属、诺卡氏菌属、小单孢菌属和野野村菌属。     

药用植物功能基因

药用植物功能基因研究是药用植物基因研究中最活跃的领域。以药用植物功能基因在GenBank中注册的统计数据为基础 ,介绍了药用植物功能基因研究的最新进展。注册的功能基因涉及 32属 42种药用植物。统计数据包括 :自 1 992年至 2 0 0 3年 (前 9个月 )每年注册基因总数、基因注册数最多的 1 6种主要的药用植物以及在药用植物功能基因研究方面比较活跃的 1 4个国家。还重点报道了植物功能基因专利注册情况、黄酮类化合物与紫杉醇生物合成基因研究进展以及植物P45 0基因研究现状 ,对药用植物生物合成功能基因研究的发展趋势进行了探讨。     

白木香叶解剖结构的研究

用石蜡切片法制片,光学显微镜观察,研究白木香叶的解剖结构。结果表明,白木香叶为典型的异面叶,但同时还表现出许多旱生形态。表皮由一层排列紧密形状不规则的表皮细胞组成,细胞外壁角质膜较厚。上表皮角质膜一般较下表皮角质膜厚1μm,下表皮上零星分布着单细胞表皮毛。气孔仅分布在下表皮上,微下陷,气孔类型为无规则型。叶肉组织发达,其间分布着较多的长方晶体,其细胞长轴与表皮垂直。栅栏组织由1—2层排列整齐的圆柱形细胞组成。栅栏组织的外层细胞转化为异细胞,海绵组织内具有一层由异细胞组成的下皮层;横切面上栅栏组织厚度与海绵组织厚度之比为1：3。主脉发达,有异细胞组成的维管束鞘,具双生韧皮部。叶内具有发达的木质部外纤维。这些特征与旱生环境相适应。     

西北产6种药用柴胡营养器官的比较解剖学研究

柴胡是伞形科柴胡属植物,据报道,全世界有150种左右,主要分布在北半球及亚热带地区,初步统计我国有30余种。据我们在西北五省调查,药用种类有21种之多,药用主流种类有柴胡Bupleurum chinesis DC.、狭叶柴胡B. scorzonerifolium Willd.、银州柴胡B. yinchowense Shan et Y. Li、小叶黑柴胡B. smithii Wolff. var. parvi-