ANTINEOPLASTIC ACTIVITY OF CULTURED BLUE-GREEN ALGAE (CYANOPHYTA)1

A large-scale screening program was initiated to evaluate laboratory-cultured blue-green algae (cyanobacteria) as a source of novel antineoplastic agents. Approximately 1000 cyanophyte strains from diverse habitats were cultured to provide extracts for testing. The screening program identified the families Scytonemataceae and Stigonemataceae as prolific producers of novel cytotoxic compounds. Rates of rediscovery of known compounds were relatively low.     

EFFECT OF BLUE-GREEN LIGHT ON PHOTOSYNTHETIC PIGMENTS AND CHLOROPLAST STRUCTURE IN THE MARINE DIATOM STEPHANOPYXIS TURRIS1

Blue-green light increased the chlorophyll concentration and chloroplast number of cells of Stephanopyxis turris (Grev.) Ralfs, compared to white light controls. Light fields for growth were 400 μW·cm^?2 (12:12 LD cycles). Chlorophyll increased up to 100%/cell, but no change in the ratio of chlorophylls to major carotenoids occurred. The effect was, therefore, not that of complementary chromatic adaptation. At the same time, blue-green light enhanced the photosynthetic fixation of CO₂. At the ultrastructure level, an increase in, and rearrangement of, the thylakoid system occurred.     

蓝藻固氮酶钼铁蛋白的研究

改进了蓝藻固氮酶的分离、提纯方法。首次用小型厌氧聚丙烯酰胺凝胶制备电泳法,代替常用的层析法,获取了电泳纯的蓝藻固氮酶钼铁蛋白,简化了程序,缩短了实验周期。SDS凝胶电泳和分子筛凝胶过滤测定分子量结果表明,钼铁蛋白分子量为360,000,由4个分子量为90,000的同一类型亚单位构成。每个钼铁蛋白分子含1个钼,18个铁和3290个氨基酸残基。其中酸性氨基酸占优势。研究了柱孢鱼腥藻(Anabaena cylindrica)固氮酶粗提物和钼铁蛋白的某些特性,其结果是:米氏常数为3.33×10~(-3)大气压乙炔,等电点为5—5.5。紫外、可见光谱与其它固氮生物的类似。盐对蓝藻固氮酶较之对其它固氮生物的固氮酶有更大的抑制作用。     

COMPARATIVE PHYSIOLOGY AND MORPHOLOGY OF SIX STRAINS OF STIGONEMATACEAN BLUE-GREEN ALGAE1

Six strains of branched blue-green algae were examined in a search for lines to an explanation for apparent noncompetitiveness. Classical taxonomic treatments were often inadequate for confident species determination; forms that were very differ their morphologically frequently “keyed” to the same species. Strain distinctions based on comparative morphological and physiological studies were inconclusive. With the exception of 1 species, there were no substantial differences in physiological rates. In addition to the branching habit, diversity of cellular form was found to be an outstanding group characteristic. Individual cells of developing trichomes became a spore-like and then divided to produce either cell clusters or lateral branches. The eventual separation of daughter cells by sheath materials may be analogous to spore formation in Nostocales and could be the factor which determines the nature of these organisms. The Stigonemataceae may not represent the pinnacle of blue-green algal development but may, instead, be a primitive and basic form linking coccoid and filamentous algae.     

低温对氯化钠胁迫下蓝藻固氮活性的影响

低温加剧氯化钠对蓝藻固氮的抑制,营养液中氯化钠浓度增高时,抑制程度更甚.能源受限(暗处理和加抑制剂时的光合受抑,N_2和Ar的厌氧下呼吸代谢受阻)和氧下固氮酶受到伤害时,低温处理使氯化钠对蓝藻固氮的抑制进一步加剧.在能源和还原剂供应,合成固氨酶蛋白的物质基础(如CO_2和N_2的加合).光合作用正常进行的条件得到改善和保证,以及供应CO_2、外源蔗糖和氮氧加合时,低温加剧氯化钠对蓝藻固氮的抑制程度明显变小.     

EFFECT OF VITAMIN CONCENTRATIONS ON GROWTH AND DEVELOPMENT OF VITAMIN-REQUIRING ALGAE1

Vitamin-requiring marine algae, Cyclotella nana, Monochrysis lutheri, and Amphidinium carterae, were grown in batch culture with limiting concentrations of vitamin B₁₂, thiamine, and biotin, respectively. Cell numbers, average cell volumes, biomasses, ¹¹CO₂ uptake rates, and chlorophyll a contents were determined daily. Maximum ¹⁴CO₂ uptake rates in most vitamin concentrations were obtained at 2 days with C. nana and M. lutheri and at 4 days with A. carterae after starved cultures were exposed to the vitamin. Radiocarbon uptake rates approximately reflect biomass increases. Cell numbers were proportional to vitamin concentrations when cells were incubated for 2 to 3 more days. Cell sizes varied depending on time of incubation. Chlorophyll a content did not always reflect vitamin concentrations. Maximum carbon assimilation rates (K_m) and saturation constants (K_s) determined from ¹⁴CO₂, uptake rates in different vitamin concentrations during early incubation were higher than when determined from cell number in log phase growth. Dissolved vitamin B₁₂, thiamine, and biotin in many samples of seawaters were in the ranges which influence the growth rate, cell size, and chlorophyll a content of C. nana, M. lutheri, and A. carterae, respectively, in laboratory studies. The effects of vitamins on these algae in situ may be similar.     

PREPARATION OF METABOLICALLY ACTIVE PROTOPLASTS OF BLUE-GREEN ALGAE1

Protoplasts that remained metabolically active for several days were obtained by treating cells of Microcystis aeruginosa, Anacystis nidulans, and Anabaena flos-aquae with lysozyme. Photosynthetic and respiratory rates were near those of control cells. Lysozymeresistant cells were isolated which may be genetic mutants.     

PROTEIN PHOSPHATASE INHIBITORY ACTIVITY IN EXTRACTS OF CULTURED BLUE-GREEN ALGAE (CYANOPHYTA)1

A large-scale screening program was initiated to evaluate laboratory-cultured blue-green algae (cyanobacteria) as a source of novel compounds with inhibitory activity against certain serine/threonine protein phosphatases. Over 1600 extracts, representing 816 cyanophyte strains with broad habitat and taxonomic diversity, were screened. Inhibitors were identified in extracts produced from all orders tested except Chamaesiphonales, and the family Stigonemataceae was found to contain proportionally more inhibitors as compared to the total screen.     

SIMPLE CONDITIONS FOR GROWTH OF UNICELLULAR BLUE-GREEN ALGAE ON PLATES1, 2

The efficiencies of plating of 2 cultures of unicellular blue-green algae, 1 coccoid and 1 rod-shaped, were studied systematically. Reproducible colony growth and accurate viable counts are dependent on the use of a low agar concentration, and on the sterilization of the agar separately from the mineral components of the medium.     

ENRICHMENT OF SURFACE FRESHWATER MICROLAYERS WITH ALGAE1

Using a variety of techniques for sampling micro-layers in freshwater environments, the frequent occurrence of significant and striking differences in algal community structure and densities relative to subsurface water is demonstrated.