爪哇曲壳藻亚缢变种胞外多聚物提取方法及其化学组成研究

优化了爪哇曲壳藻亚缢变种(Achnanthes javanica var. subconstricta)胞外多聚物提取方法并分析了其化学组成。结果表明, 使用0.3 mol/L的碳酸氢钠提取时间为2.53h可充分提取非水溶性胞外多聚物而不会破碎细胞, 是最优的提取方法。爪哇曲壳藻亚缢变种胞外多聚物多糖占80%以上, 蛋白质占16%19%, 不含脂类。水溶性多糖的单糖组分摩尔比为: 岩藻糖:半乳糖:葡萄糖:甘露糖:木糖:鼠李糖=2.47:2.13:1:0.69:0.57:0.46,而非水溶性多糖的单糖组分摩尔比为: 半乳糖:岩藻糖:木糖:葡萄糖:甘露糖:鼠李糖=3.56:2.73:1.30:1:0.67:0.57。     

FINE STRUCTURE OF THE DIATOM AMPHIPLEURA PELLUCIDA. II. CYTOPLASMIC FINE STRUCTURE AND FRUSTULE FORMATION

The general arrangement of cytoplasmic organelles in Amphipleura pellucida Kutz. is similar to that in other naviculoid diatoms. The chromatophores are parietal with a single, non-membrane-limited, pyrenoid. The pyrenoid is crossed by several double-disc lamellar bands which are occasionally interrupted by less dense areas containing convoluted tubules. Similar areas also interrupt the three-disc bands of the chromatophores. The nucleus is irregular in shape. The outer membrane of the porous nuclear envelope outfolds around the chromatophore. A perinuclear dictyosome complex is present. Amorphous dense bodies are formed in elaborations of the dictyosomes. Vesicles, both with and without dense inclusions, are formed by the dictyosomes during cell division and a role is suggested for these vesicles in both cytokinesis and frustule development. The first evidence of frustule formation is the deposition of the siliceous median rib within a membranous sac. This sac expands laterally to form the silica deposition vesicle which appears to serve as a mold for the formation of the valve. After the valve is formed, the membranes and the small amount of cytoplasm external to it are sloughed off.     

THE CYTOPLASMIC FINE STRUCTURE OF THE DIATOM, NITZSCHIA PALEA

The cytoplasmic fine structure of the motile, pennate diatom, Nitzschia palea was studied in thin sections viewed in the electron microscope. The cells were fixed in OsO₄, embedded in methacrylate, and immersed in 10 per cent hydrofluoric acid (HF) for 36 to 40 hours to remove the siliceous cell wall prior to sectioning. The HF treatment did not cause any obvious cytoplasmic damage. The dictyosome complex is perinuclear, and located only in the central cytoplasm. Mitochondria are sparse in the central cytoplasm, but abundant in the peripheral cytoplasm, and fill many of the transvacuolar cytoplasmic strands. Characteristic, amorphous oil bodies fill certain cytoplasmic strands and probably are not leucosin. The pyrenoid appears to be membrane limited, and oil droplets are found adjacent to the pyrenoid. The pyrenoid of another diatom, Cymbella affinis, is also membrane-limited. The membrane limiting the pyrenoid may be a composite of the terminal portions of chloroplast discs, facilitating rapid movement of photosynthate into the pyrenoid matrix, where the characteristic oil droplets may be formed. Carinal fibrils are found singly in each carinal pore, and may be involved in the locomotion of Nitzschia palea.     

SORPTION OF FERROUS AND FERRIC IRON BY EXTRACELLULAR POLYMERIC SUBSTANCES (EPS) FROM ACIDOPHILIC BACTERIA

The sorption of Fe(II) and Fe(III) by extracellular polymeric substances (EPS) of acidophilic bacteria Acidiphilium 3.2Sup(5) and Acidithiobacillus ferrooxidans, harvested from the ecosystem of the Tinto River (Huelva, Spain), was investigated. EPS from mixed cultures of both bacteria (EPS_mixed) and pure cultures of A. 3.2Sup(5) (EPS_pure) were extracted with ethylenediamine tetraacetic acid (EDTA) and were characterized by Fourier-transform infrared (FTIR), electron photoemission (XPS), x-ray diffraction (DRX), and energy dispersive x-ray (EDX) spectroscopy and scanning electron microscopy (SEM). EPS _pure were loaded, in sorption tests, with Fe(II) and Fe(III). The results obtained indicate that the biochemical composition and structure of EPS_mixed was very similar to that of EPS_pure. Besides, results indicate that EPS_mixed adsorbed Fe(II) and Fe(III) by preferential interaction with the carboxyl group, which favored the formation of Fe(II)/Fe(III) oxalates. These species were also formed in EPS_pure loaded with Fe(II)/Fe(III). All this behavior suggested that the sorption of iron by EPS_mixed was similar to sorption of EPS_pure, which fitted the Freundlich model. Thus, the iron uptake of EPS_mixed reached 516.7 ± 23.4 mg Fe/g-EPS at an initial concentration of 2.0 g/L of Fe_total and Fe(II)/Fe(III) ratio of 1.0.     

COMPOSITION OF EXTRACELLULAR POLYMERIC SUBSTANCES FROM PERIPHYTON ASSEMBLAGES IN THE FLORIDA EVERGLADES1

In wetland habitats, periphyton is a common component of open‐water areas with species assemblage determined by local water quality. Extracellular polymeric substances (EPS) secreted by algae and bacteria give structure to periphyton, and differences in EPS chemistry affect the functional roles of these polymers. The Florida Everglades provide a unique opportunity to study compositional differences of EPS from distinctive algal assemblages that characterize areas of differing water chemistry. Water conservation area (WCA)‐1 is a soft‐water impoundment; periphyton was loosely associated with Utricularia stems and amorphous in structure, with a diverse desmid and diatom assemblage, and varying cyanobacterial abundance. Extracellular polymers were abundant and were loosely cell‐associated sheaths and slime layers in addition to tightly cell‐associated capsules. The EPS were complex heteropolysaccharides with significant saccharide residues of glucose, xylose, arabinose, and fucose. Carboxylic acids were also prominent, while ester sulfates and proteins were small components. Structured, cohesive cyanobacteria‐dominated periphyton was observed in WCA‐2A, a minerotrophic impoundment, and filaments were heavily encrusted with calcium carbonate and detrital matter. EPS were primarily cell‐associated sheaths, and polymer residues were dominated by glucose, xylose, fucose, and galactose, with uronic acids also a significant component of the polymers. Principal components analysis revealed that periphyton community assemblage determined the monosaccharide composition of EPS, which ultimately determines a range of biogeochemical processes within the periphyton.     

蓝藻胞外多聚物生物合成、群体形成与微囊藻水华

有毒微囊藻水华在太湖、巢湖和滇池等饮用水源地频繁暴发,对居民健康和水产养殖等构成严重威胁,亟需开发新技术加以有效控制和利用。在水华暴发时,蓝藻大量分泌胞外多聚物而形成细胞群体,是蓝藻水华发生的关键和前提。蓝藻群体中胶质状胞外多聚物由胞外多糖、蛋白质和其他生物大分子组成,对其结构、功能和生物合成途径研究了解仍然有限。生物信息学和比较基因组学分析发现微囊藻和其他多种蓝藻中编码大量的具有称之为PEP-CTERM结构域的潜在胞外蛋白质,这些潜在的蛋白质可能通过特殊的分选系统分泌到细胞表面,与胞外多糖相互作用形成结构更复杂的胞外多聚物,介导细胞群体的形成和水华发生。亟需建立微囊藻遗传操作技术,深入揭示胞外多聚物生物合成和群体形成的分子机制,寻找控制蓝藻胞外多聚物的组装和分泌及群体形成的关键靶点,将有助于揭示蓝藻水华形成机理及开发新型控藻技术。     

THE FINE STRUCTURE AND FUNCTION OF THE CONTRACTILE AXOSTYLES OF CERTAIN FLAGELLATES

The axostyles of the flagellates Oxymonas, Saccinobaculus, and Notila are large ribbon-shaped structures which undulate actively in the cytoplasm. The form of their movements is described and illustrated. Axostyles consist of regular arrays of longitudinal fibres, the number of which varies between 100 and 5000 in different species. The fibres are about 240 A in diameter, apparently hollow, regularly cross-banded with a periodicity of about 150 A, and connected by delicate cross-links, also at regular intervals of about 150 A. They resemble very closely the central fibres of cilia and flagella. No other structural components are present, except at the anterior end, where the fibres are attached to one or more basal bodies, and at the posterior tip, where they are anchored to the plasma membrane. The relevance of the findings to an understanding of the mechanism of ciliary and flagellar movements is discussed.     

SECRETORY CELLS OF LILY PISTILS. I. FINE STRUCTURE AND FUNCTION

The fine structure of the cells which line the canal of Lilium longiflorum pistils confirms the secretory function which has been ascribed to them. The cells differ in structure from the secretory cells which cover the stigma surface and are therefore referred to as canal cells rather than stigmatoid cells. Their most striking feature is an elaborate wall, 8–14 μ in maximum depth, on the side facing the canal, which with associated structures, we term the secretion zone. Pollination, which triggers chemotropic activity in the style and secretory activity in the canal cells, is not correlated with marked changes in the fine structure of the canal cells. The canal cells appear to fit well into that category which Gunning and Pate have termed “transfer cells.”     

THE MARINE DIATOM THALASSIOSIRA OESTRUPII: STRUCTURE,TAXONOMY AND DISTRIBUTION

Thalassiosira oestrupii (Ostenfeld) Hasle was studied from the southern Indian Ocean, Wed-dell Sea, and northern Atlantic Ocean. It has the longer extension of the strutted process inwards, with three small columnar supports. A single strutted process near the central areola is 2-3 areolae away from the single labiate process; both are usually visible in the light microscope. Two bands are septate: the valvocopula (intercalary band next to the mantle) is ribbed with a complex pattern of pores, while the other intercalary band (copula) present has but a single ring of large pores. T. oestrupii var. venrickae is described from warmer water with similar bands but with differences in areolae array and spacing of marginal strutted processes. It was found in the Gulf of Mexico, eastern and western Atlantic Ocean, Indian Ocean, and western Indian Ocean. The two varieties appear to differ in their ecology and distribution, with T. oestrupii var. oestrupii apparently a cosmopolitan oceanic taxon and T. oestrupii var. venrickae a tropical and subtropical continental shelf taxon.     

CELL WALL CHEMISTRY AND FINE STRUCTURE IN LEPTOIDS OF DENDROLIGOTRICHUM (BRYOPHYTA): THE END WALL

Leptoids (sieve elements) of Dendroligotrichum are characterized by a highly oblique end wall which is composed of cellulose (birefringent; IKI-H₂SO₄-positive), polyuronides (toluidine blue-positive), pectins (hydroxylamine-positive) and natural aldehydes (silver hexamine and silver proteinate-positive). Cytochemically the end wall appears identical to the unevenly thickened lateral wall. Electron cytochemical localization of aldehydes with silver proteinate reveals two distinct wall layers in comparison to the 3-layered lateral wall. Plasmodesmata are present in the end wall with a frequency of 15-20 per μm². A characteristic feature of end wall plasmodesmata is an expanded median cavity which is 0.12-0.15 μm in diameter. Frequently an electron-dense substance, whose chemical nature and origin are unknown, occludes the plasmodesmata.     

爪哇伪枝藻胞外多糖诱导皮肤癌细胞(A431)凋亡的研究

为探讨爪哇伪枝藻胞外多糖(Extracellular polymeric substances of Scytonema javanicum, EPS)诱导人表皮癌A431细胞凋亡及其对凋亡相关基因caspase-3、bcl-2和bax表达的影响,本实验利用MTT法检测细胞生长抑制情况;HE染色法及透射电镜进行形态学观察;单细胞凝胶电泳法(SCGE/彗星电泳)分析DNA受损情况;免疫组织化学法检测细胞内caspase-3、bcl-2和bax表达水平。结果显示EPS能显著抑制A431细胞增殖,并呈时间和剂量依赖性,作用96h的半数抑制浓度IC50为4.25mg/mL,并出现细胞凋亡的形态学改变;彗星电泳结果与对照相比6mg/mL EPS作用48h能引起A431细胞DNA严重损伤;免疫组织化学检测发现6mg/mL EPS作用72h能显著上调A431细胞内凋亡相关基因caspase-3和bax的表达,而下调bcl-2的表达。     

EXTRACELLULAR MATRIX PROTEO‐GLYCANS INVOLVED IN DIATOM ADHESION AND MOTILITY

Although diatom extracellular matricies are usually thought of exclusively in terms of the beautiful, architecturally complex silicious frustule, polymers exuded through the frustule are critical mediators of interactions with the external environment. In several species, complex proteoglycans appear to be the primary components involved in adhesion and motility. When viewed with high‐resolution cryo‐scanning electron microscopy methods, the ubiquity and pervasiveness of these polymers was revealed in both freshwater and marine taxa. Monoclonal antibody mapping of carbohydrate epitopes characterized by NMR, methylation and monosaccharide analysis and correlated with structural observations by EM revealed an organizational pattern far more complex than previously proposed. Modeling assembly of extracellular “stalks” in the marine biofouling diatom Achnanthes longipes involves intracellular sequestering of multiple components, deposition at the protoplasmic membrane/diatotepum interface, transport through the multilayered diatotepum and holes in the silica, extrusion from the frustule, and assembly into a very complex multi‐laminate biocomposite structure. The mechanism of extracellular polymer participation in motility is complex in a different way, as some current models of raphe associated motility involve cytoskeletal interactions and molecular motors.     

禾本科牧草植物的结构、生长特性及其生理学基础

阐述了禾本科牧草植物形态结构特征,生长特点及其光合生理基础,比较了暖季Ｃ４型牧草和寒季Ｃ３型牧草的差异。对不同发育阶段牧草的田间管理以及提高水分利用效率的途径进行了讨论．     

THE FINE STRUCTURE AND FUNCTION OF THE SALIVARY GLANDS OF NUCELLA LAPILLUS (GASTROPODA: MURICIDAE)

The fine structure of the tubular and acinous salivary glandsof Nucella lapillus (L.) has been studied and some histochemicaland enzyme tests have been carried out. The clusters of subepithelialcells of the tubular glands secrete a glycoprotein composedof chains of tubular macromolecules resembling secretions knownto have adhesive properties which may assist in boring. Thesecretion is rich in disulphide groups, as are many toxins,and is believed to be responsible for the recently demonstratedpharmacological activity of the glands. It is proposed thatflaccid paralysis is induced in prey by envenomation with thissecretion during rasping, after soft parts have been exposedby an ‘anti-predator’ reaction to secretion fromthe hypobranchial gland of Nucella. The secretory vesicles ofboth types of gland cells in the acinous glands have heterogeneouscontents indicating that their secretions are complex. The majorcomponent in those of the mucous cells is an acid mucopolysaccharidetypical of a lubricant or releasing agent. The ciliated basalcells resemble typical enzyme-secreting cells and the majorconstituent of their secretion is a finely granular glycoprotein. (Received 8 January 1990; accepted 5 June 1990)