几种固氮蓝藻的固氮酶活性及其某些特性

对三种固氮蓝藻:固氮鱼腥藻(水生686)、柱孢鱼腥藻和鱼腥藻7120的整细胞及无细胞抽提液的固氮酶活性,进行了比较研究。水生686的整细胞酶活虽然不低(51.9毫米乙烯峰高/光密度/30分),仅次于柱孢鱼腥藻,但其无细胞抽提液的酶活却最低。这可能与它含有大量藻胶有关。研究了Mn++、Fe++对蓝藻固氮酶的作用,以及测定其在不同酶浓度下的反应动力学表明:柱孢鱼腥藻中不存在象深红螺菌中所看到的那种激活因子。用甲苯-乙醇溶液处理藻细胞,对固氮酶作原位测定,探索了它的氧损伤及氧保护机理。       

THE NORMAL AND INDUCED OCCURRENCE OF CYANOPHYCIN INCLUSION BODIES IN SEVERAL BLUE-GREEN ALGAE1

Multi-L-arginyl-poly(L-aspartic acid) [arg-poly(asp)], the polypeptide component of the cyanophycin inclusion body, is found in cells of many blue-green algae. Formation of this material can be induced by a variety of treatments including the addition of excess nitrogen-containing compounds, the addition of specific inhibitors of macromolecular synthesis, and the exclusion of sulfur or phosphorus. Knowledge of the conditions that induce the synthesis of this polypeptide has made possible an ultrastructural survey to determine the presence and cellular location of cyanophycin bodies in a variety of cyanobacteria. Data presented show that certain strains of the unicellular genus Synechococcus Nägeli do not contain arg-poly(asp) under environmental conditions that markedly increase the level of such material in other cyanobacteria. In addition many strains show spatial localization of the cyanophycin bodies under normal growth conditions, and moreover the normal pattern is retained even when massive synthesis of arg-poly(asp) is induced. Finally there is no evidence that these inclusion bodies occur in certain beggiatoan gliding bacteria.     

A QUALITATIVE AND QUANTITATIVE STUDY OF PLASTOQUINONE A IN TWO THERMOPHILIC BLUE-GREEN ALGAE1

The thermophilic blue-green alga Synechococcus lividus strain Y52 was shown to have plastoquinone (PQ) types A, B, and C. The values PQA per cell and chlorophyll a per cell are presented with the changes in the ratio of PQA to chlorophyll a for cells grown at different light intensities.     

MITOSIS AND CLEAVAGE DURING ZOOSPOROGENESIS IN SEVERAL COCCOID GREEN ALGAE1

The fine structure of mitosis and cleavage in Axilosphaera vegetata Cox & Deason, Chlorococcum echinozygotum Starr, Chlorosarcinopsis eremi Chantanachat & Bold, Nautococcus mammilatus Korshikoff, N. terrestris Archibald, N. soluta Archibald, Neospongiococcum solitarium Deason, and Tetracystis aeria Brown & Bold was observed. All possess a phycoplast, but differences in basal body position during mitosis were observed. Nautococcus mammilatus differs from the others as protoplast rotation occurs in many cells prior to cleavage.     

蓝藻球形体的分离,培养及再生

在高渗溶液中,用0.05%溶菌酶和2—5mmol·1~(-1)EDTA 处理蓝藻柱孢鱼腥藻、多变鱼腥藻和组囊藻细胞。5—8h 后,70—90%的细胞转为对渗透压敏感的球形体(Spheroplast),又称原生质球。研究了藻的不同培养条件对球形体形成率的影响。测定了 EDTA 处理藻纽胞后外膜脂多糖的释放量。在高渗溶液中,藻细胞和经酶处理获得的球形体的光合放氧活性明显下降,固氮种类的固氮活性失去。饲养层法、固体混合法和含有0.5mg·1~(-1)BA 的液体悬滴培养的柱孢鱼腥藻的球形体,9天后出现再生藻落;在固体混合法培养中获得了组囊藻球形体的再生藻落。在第4天的悬滴培养物中,可以看到球形体发生第一次细胞分裂。再生藻细胞和酶处理物中残留细胞的抗溶菌酶特性有差异。     

蓝藻原生质球研究的现状及存在问题

在原生质体(球)技术方面,蓝藻也许是一种最为困难的材料了。蓝藻原生质球的研究工作起步不算很晚,但进展不快。直到现在,作为一项可以用于遗传操作的基本技术还没有建立起来。这主要表现在,原生质球的再生问题没有解决;此外,在基本分离制备方面也存在不少问题。而对于植物、真菌、细菌、放线菌和绿藻,这些问题都早已     

固氮蓝藻培养和应用的结果与展望

固氮蓝藻是一类低等原核植物。它能进行固氮作用,固定空气中分子态氮成为氮素化合物;又能进行光合作用,将二氧化碳变为碳素化合物并放出氧气,为自身的固氮提供能源和还原剂。由于具有以上功能,它们适应性很强往往是贫瘠土壤的先驱植物,因此,很早就引起了人们的重视。       

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.     

THE CAROTENOIDS OF FOUR BLUE-GREEN ALGAE1

The carotenoids of 4 species of blue-green algae, Anabaena variabilis, Phormidium persicinum, P. ectocarpi, and P. fragile, were investigated. In each, ft-carotene was a major pigment and the only carotene detected. The xanthophylls present in Anabaena variabilis were echinenone, canthaxanthin, and myxo-xanthophyll. Each of the Phormidium species contained zeaxanthin as the major xanthophyll. In each, this was accompanied by trace amounts of echinenone and isocryptoxanthin. In addition, 2 new xanthophylls, spectrally resembling ^-carotene, were found in Phormidium persicinum and P. ectocarpi, while another, with a spectrum similar to that of myxoxanthophyll, was found in P. fragile.     

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.     

甘露醇对蓝藻细胞的作用

甘露醇引起蓝藻营养细胞破裂,这种作用与甘露醇的浓度、作用时间、处理温度、pH值及细胞生长时期有关。     

青霉素对蓝藻细胞的作用

1967年,Biggins首次报道通过溶菌酶处理获得了有生活力的篇藻(Phormidium luridum)原生质球。此后,虽然许多作者在这方面作了不少工作,但原生质球的再生和融合问题至今没有得到解决。再生和融合与分离制备方法密切相关,因此,     

蓝藻(Anabaena 7120)的光合放氢和参与放氢的酶

蓝藻Anabaena 7120放氢是一个依赖于光的过程,暗中几乎测不出放氢活性。静置方式培养的蓝藻预先进行强化培养是测得高放氢活性的重要条件。年轻的蓝藻放氢活性比年老的高。氯化铵和一系列光合作用抑制剂对蓝藻放氢有抑制作用,弱光加剧氯化铵对放氢的抑制。在弱光加光合抑制剂的条件下,受氯化铵抑制的放氢活性恢复速度比强光下慢。CO_2、N_2、NaN_3和KNO_3与放氢竞争电子而抑制蓝藻的放氢。C_2H_2促进蓝藻放氢,CO则抑制放氢,C_2H_2和CO一起加入时,放氢受到的促进显著比单加C_2H_2的大。经分子氢预处理过的蓝藻,其放氢活性在光下可以得到明显的促进。     

THE HETEROCYSTS OF BLUE-GREEN ALGAE (MYXOPHYCEAE)

1. Heterocysts are found in many species of filamentous blue-green algae. They are cells of slightly larger size and with a more thickened wall than the vegetative cells. 2. Structural details of the heterocyst are: the presence of three additional wall layers, the absence of granules, sparse thylakoid network throughout, except at the poles where a dense coiling of membranes occurs. Other characters include the two pores at opposite poles ‘plugged’ with refractive material called the polar granule. 3. Peculiarities in the pigment composition of the heterocyst include an abundance of carotenoids and absence of phycobilins, and a short-wave form of chlorophyll a. 4. Unique glycolipids and an acyl lipid, not found in the vegetative cells of the algae or in other plant cells, are associated with the heterocyst. The glycolipids constitute the laminated layer of the wall and probably regulate diffusion of substances through it, whereas the acyl lipids are supposed to function as carriers and intermediates in the biosynthesis of the wall. 5. The heterocysts develop from vegetative cells, and the visible changes during differentiation include cell enlargement, synthesis of additional wall layers, disappearance of granules and reorientation and synthesis of the thylakoids. 6. Heterocysts are formed sequentially with characteristic cellular spacing during the growth of cultures in medium free from combined nitrogen. 7. Various sources of combined nitrogen inhibit heterocyst formation when supplied in the culture medium. Ammonium salts are among the most powerful inhibitors. Heterocysts are formed simultaneously and within a short period after transference of ammonia-grown non-heterocystous filaments to ammonia-free medium. 8. Incompletely differentiated heterocysts or proheterocysts are found in cultures grown in the presence of combined nitrogen. If two or more proheterocysts are close together generally a single one develops to maturity after a competitive interaction in medium free from combined nitrogen. This indicates that heterocyst formation is completed in two phases: phase I, synthesis and conservation of macromolecules, which takes place during growth in ammonia-containing medium: and phase 11, morphological differentiation of the heterocyst which is unaccompanied by growth in cell number. In the ammonia-free medium phase 11 quickly succeeds phase 1 and the whole process appears as a continuum. 9. Heterocyst formation shows a definite requirement for light. Red light favours heterocyst formation, whereas green and blue light do not. The effects of light seem to be mainly due to photosynthesis, although some effects may be morphogenetic. 10. Studies with metabolic inhibitors have revealed the involvement of photosynthesis, respiration and protein synthesis in heterocyst formation. Photosynthesis provides carbon skeletons, whereas ATP is most probably supplied by oxidative metabolism. 11. Various functions have been assigned to the heterocyst from time to time. Their role in akinete formation is suggested by (i) the formation of akinetes adjacent to the heterocysts and (ii) prevention of sporulation by detachment of the heterocysts from the vegetative cells (potential akinetes). Despite substantial evidence for such a role, it is not applicable to all akinete-forming genera. 12. Heterocysts are now widely believed to be the site of nitrogen fixation in blue-green algae. The main facts in favour of such a role are: (i) fixation of nitrogen by all heterocystous algae, (ii) inhibition of heterocyst formation by combined nitrogen and (iii) direct observations on acetylene reduction by isolated heterocysts. 13. Some non-heterocystous and unicellular algae, and vegetative cells of heterocystous algae fix nitrogen under microaerophilic conditions suggesting that absence of oxygen favours nitrogenase activity. Heterocysts lack the oxygen-evolving photo-system 11, possess oxidative enzymes, and reduce externally supplied tetrazolium salts - all indicating that they are the most suitable sites for harbouring nitrogenase in aerobic conditions. 14. Heterocysts probably originated in the Precambrian in response to the earth's changing environment and seem to be the first example of morphological differentiation in the plant kingdom.