ON SPECTRAL CONTROL OF PIGMENTATION IN ANACYSTIS NIDULANS (CYANOPHYCEAE)1,2

Growth of Anacystis nidulans (Richt.) Drouet & Daily in wavelengths of light predominantly absorbed by chlorophyll a causes a dramatic lowering in chlorophyll content and in the chlorophylllphycocyanin ratio. A limit to the effect is reached in far red (680 nm) light where the ratio chlorophylllphycobilinogen falls to <0.3. A special water bath for culture tubes was illuminated by tungsten-halogen lamps through far red (>650 nm)filters; it gave the same extreme pigment ratio together with a high specific growth rate of 2.5 day^-1. Compared with normally pigmented cells there are three features which accompany the low-chlorophyll condition of far red light. At 677 nm relative quantum efficiency increases but action decreases. Synthesis of total pigment and total cell material in far red light also decreases. These observations suggest that the low chlorophyll response to far red light reflects an incompetence rather than an adaptation.     

GLYOXYLATE CYCLE ENZYME ACTIVITIES IN THE CYANOBACTERIUM ANACYSTIS NIDULANS1

The enzymes of the glyoxylate cycle, isocitrate lyase (EC.4.1.3.1) and malate synthase (EC.4.1.3.2), were measured in cell-free extracts from the cyanobacterium Anacystis nidulans Drouet during photoautotrophic growth in medium aerated with ordinary air (0.03% CO₂). Isocitrate lyase had an average specific activity of 112 nmoles·min^?1·mg protein^?1 whereas malate synthase had an average specific activity of 12.5 nmoles·min^?1·mg protein^?1. Unpurified isocitrate lyase showed classical Michaelis kinetics with a K_m of 8 mM. Isocitrate lyase activity was strongly inhibited by numerous cellular metabolites at 10 mM concentration. The previously reported low specific activity for isocitrate lyase may be due to metabolite inhibition caused by growth in high CO₂ concentrations. The activities reported for isocitrate lyase and malate synthase suggest the operation of the glyoxylate cycle in Anacystis nidulans under CO₂-limiting growth conditions.     

EXTRACELLULAR LYSIS OF THE BLUEGREEN ALGA PHORMIDIUM LURIDUM BY BDELLOVIBRIO BACTERIOVORUS1

When either cells of the bacterium, Bdellovibrio bacteriovorus (Stolp & Starr), strain 15143, or a heat-resistant lytic factor derived from these cells is added to viable cultures of Phormidium luridum var. olivacea Boresch all the algal cells underwent gradual lysis. This effect was obtained with a mean initial bdellovibrio:algal cell ratio of 7.5:1. When P. luridum was mixed with the bdellovibrio cultures the algal chlorophyll content showed an 8-fold decrease. Concomitantly, this interspecies interaction caused, a 75% inhibition of algal photosynthesis after-4 h. Heat, treatment of the B. bacteriovorus culture supernatant fluid increased its ability to inhibit photosynthesis approximately 14%. Light, microscopy showed pale granules and intracellular spaces to form in the P. luridum within 16 h after adding the bdellovibrio lytic factor. Subsequent morphological changes included the development of large intracellular spaces, intercellular spaces, spheroplast formation and finally Complete lysis of the algal cells.     

ENHANCEMENT OF INTRACELLULAR PROLINE LEVEL IN CELLS OF ANACYSTIS NIDULANS (CYANOBACTERIA) EXPOSED TO DELETERIOUS CONCENTRATIONS OF COPPER1

The intracellular proline level in Anacystis nidulans cells was enhanced when the cells were exposed to sublethal concentrations of Cu²⁺; the degree of enhancement was positively related to the concentration of Cu²⁺. Analysis by high-performance liquid chromatography confirmed that the enhancement of proline levels was the most pronounced change in the composition of the free amino acid pool during copper treatment. A direct supply of exogenous proline to the cultures lowered the inhibitory influence of Cu²⁺on the growth of cells. Further experiments showed that the supply of exogenous proline lowered the leakage of potassium ions from cells exposed to deleterious concentrations of Cu²⁺. The inhibition of potassium leakage was particularly pronounced when proline was supplied prior to Cu²⁺treatment. The present study suggests that enhanced proline protects cell membranes from being affected by deleterious concentrations of Cu²⁺.     

SPECTROPHOTOMETRICALLY ASSAYED INHIBITORY EFFECTS OF MERCURIC COMPOUNDS ON ANABAENA FLOS-AQUAE AND ANACYSTIS NIDULANS (CYANOPHYCEAE)1

The growth-related inhibitory effects of mercuric chloride (MC), methylmercuric chloride (MMC) and phenylmercuric acetate (PMA) (each at 1, 10, 10,² 10³ ppb) were measured in Anabaena flos-aquae (Lyng.) Bréb. and Anacystis nidulans (Richt.) Drouet & Daily. Optical density changes of control cultures compared against those of experimental cultures showed that MC was the least inhibitory of the compounds. MMC. was the most inhibitory, producing statistically significant inhibition at a concentration as low as I ppb in Anabaena. PMA was more inhibitory than MC but less than MMC. Effects caused by the mercury compounds included bleaching of individual cells, cell size changes and destruction of whole cells; the degree and extent of these effects depended on the compound and its concentration in the nutrient medium. The high sensitivities of the algae tested suggested the possibility of using them as test organisms in bioassays for mercury.     

MODULATION OF FATTY ACIDS IN THE MEMBRANES OF ANACYSTIS NIDULANS (CYANOBACTERIA): INCORPORATION OF ODD-NUMBERED CARBON FATTY ACIDS1

Anacystis nidulans Richt., a unicellular cyanobacterium, can incorporate exogenously supplied fatty acids, including odd-numbered carbon fatty acid (OFAs), into the acylglycerols of cell membranes. Data are presented for the uptake of undecanoic acid (11:0) into cells of A. nidulans, the subsequent elongation up to C17, and incorporation of OFA into the four major membrane acylglycerols. The incorporation of OFAs was followed by desaturation of part of the saturated fatty acid to monoenoic fatty acid. Positional analyses of the double bonds of these manoenoic fatty acids suggest that there is one desaturase that inserts a Δ⁹ bond in both odd- and even-numbered fatty acids of varying chain length. Our data also suggest that there is no positional specificity for chain length on the glycerol backbone by the acyltransferases.     

DIFFERENCES IN PHOTOSYNTHESIS-ASSOCIATED PROPERTIES OF THE BLUEGREEN ALGA SYNECHOCOCCUS CEDRORUM CROWN AT 30 AND 40 C1

The growth of Synechococcus cedrorum Saug. (UTEX 1191) at 40 C resulted in structural and functional alteratons relative to cells grown at 30 C. Structural variations included cell morphology and the chemical composition of the membrane. Growth at 40 C. produced cells that were longer and thinner than those at 30 C. The fatty acid composition changed substantially upon growth at 40 C. yielding a distribution with a higher ratio of: i) saturated to unsaturated fatty acids and; ii) longer chain unsaturated fatty acids. Furthermore, the pattern of membrane proteins as determined by sodium dodecyl sulfate electrophoresis was distinctly different. The functional changes were typified by photosynthetic rates which were approximately half those of the 30 C grown cells. A number of spectral parameters were also seen to change in 40 C. grown cells: absorption spectra indicated a higher phycocyanin : chlorophyll ratio. Low temperature fluorescence spectra were consistent with a lowered efficiency of energy transfer from phycocyanin to chlorophyll. It is suggested that the fatty acid changes at 40 C. yield a more fluid membrane which is responsible for the functional alterations. The modification of phycocyanin. chlorophyll ratios, as well as the appearance of P750, is discussed with respect to membrane fluidity.     

CHLORIDE UPTAKE BY ANACYSTIS NIDULANS (CYANOPHYCEAE)1

Anacystis nidulans (Richt.) Drouet & Daily (UTEX 625), grown in batch culture with 0.5% CO₂ in air, was supplied with chloride labelled with ³⁶Cl in light and dark. Uptake in light was stimulated relative to uptake in darkness. A single transport system for Cl^? with an apparent K_m for Cl^? of 0.14 mM was identified. Chloride in the cells reached a maximum value after 30–50 min at 25 C. At this point the internal Cl^? concentration was calculated to be 60-fold the external (0.1 mM) in light and 37-fold in darkness. DCMU (3-[3,4-dichlorophenyl]–1, 1-dime-thylurea), at concentrations which abolished photosynthetic O₂ evolution did not inhibit Cl^? uptake in light. Carbonyl cyanide m-chlorophenyl hydrazone (CCCP), at uncoupling concentrations for photosynthesis and dark respiration, strongly inhibited Cl^? uptake in light and darkness. N,N'-dicyclohexyl carbodiimide (DCCD), an energy transfer inhibitor, inhibited light Cl^? uptake more slowly than photosynthesis but had no effect on dark Cl^? uptake. It is concluded that Cl^? uptake in A. nidulans was active in light and darkness, and that ATP was the probable energy source for transport.     

IMMUNOFLUORESCENCE FOR AUTECOLOGICAL STUDY OF A UNICELLULAR BLUEGREEN ALGA12

Fluorescent antibody (FA) preparations were developed and tested as an approach to recognition and enumeration of a specific unicellular bluegreen alga in a natural ecosystem. Antibodies made against an axenic culture of Synechococcus cedrorum Näg. gave a high agglutination titer and an excellent homologous staining reaction. Antibody specificity was tested with 28 heterologous cultures of bluegreen algae, known cultures of chemoautotrophic bacteria and heterotrophic bacteria, and randomly selected unknown bacteria from soil, sewage and aquatic habitats. FA staining of bluegreen algae was restricted to S. cedrorum and six heterologous isolates, all indistinguishable microscopically from S. cedrorum. The ability to enumerate S. cedrorum FA-reactive cells in nature was demonstrated with data on population densities for samples taken from water columns of stratified holomictic lakes in northcentral Minnesota.     

ORGANIC COMPOUNDS RELEASED FROM A NATURAL POPULATION OF EPIBENTHIC BLUEGREEN ALGAE1

Extracellular release of dissolved organic compounds by the bluegreen algal community of a brackish marsh was studied using ¹⁴C techniques. Mannitol and trehalose were identified as the most commonly released compounds. The proportions of these two extracellular compounds varied in response to light intensity and the water potential of the environment. The presence of mannitol, in particular, suggests that excretion of organic compounds in natural situations is a function of osmotic adjustment.     

SUN-SHADE ECOTYPES OF A BLUEGREEN ALGA IN A HOT SPRING1,2

Clone cultures of the thermophilic alga Plectonema notatum Schmidle were established from cells collected from the high and low light intensity regions of the algal mat which developed in Jerry Johnson Hot Spring, Idaho. Clones isolated from cither high, or low light intensify zones were grown at light intensities of 8000 and 400 ft-c. The existence of specialized and genetically fixed sun or shade ecotypes was evidenced, by the ability of low light intensity clones to synthesize more light harvesting chlorophyll a when grown under low light conditions than the high light clones. High light clones showed light saturation of photosynthesis at higher light intensities with higher carboxylating enzyme activities and less chlorophyll a than low light clones when both were cultured at 8000 ft-c. These clones displayed infraspecific variation along the light intensity gradient and therefore exist as a mosaic of light, intensity ecotypes.     

SEASONAL CHANGES IN STRUCTURE OF A SUBMERGED BLUEGREEN ALGAL/BACTERIAL COMMUNITY FROM A GEOTHERMAL HOTSPRING1

The species (cytospecies) structure and seasonal dynamics of a thermophilic bluegreen algal/bacterial community from Mimbres, New Mexico are described. Using stereological techniques, several common quantitative ecological parameters (biomass, density, distribution measurements, Species Diversity Indices, importance values) were described for the community growing ca. 1 m beneath the water surface on the inner walls of a concrete cistern. Temperature and pH were relatively constant while water flow rates, duration and intensity of light showed seasonal variation. The total volume of the mat occupied by living organisms did not exceed 2% during the entire year. The remaining volume was occupied by gas and water bubble chambers, gelatinous matrix, empty tubes, mineral deposits, and water. The total biomass remained constant except during a period of severe, seasonal light reduction (November). Species Diversity Indices, density and importance values for the bluegreen algal and bacterial populations showed seasonal changes. The three dominant bluegreen algal cytospecies which represented the greatest amount of biomass alternated in their abundance on a seasonal basis while the three dominant bacterial cytospecies remained the same throughout the period of study. Although considerable season change occurred in the species structure of this community, the total living volume remained relatively constant with the major changes in the bluegreen algal populations. Many of the seasonal changes observed appear to correlate with seasonal changes in light intensity and duration.     

DISTRIBUTION OF BLUEGREEN ALGAE IN A MISSISSIPPI GULF COAST SALT MARSH1

Edaphic bluegreen algal communities were sampled from five menotypic angiosperm zones in Grvelline Bay Marsh near Ocean Spring. Mississippi. Samples and environmental data were taken on a quarterly basis from October 1976 to June 1977 beneath the following marsh angiosperms: Distichlis spicata (L.) Green, Scirpus olneyi gray, SPartina patens (Aiton) Muhl., Sp. alterniflora Loisel., and Juncus roemerianus Scheele. Communities in all five zones were dominated by Schizothrix calcicola (Ag.) Gom. (sensu Drauet) throughout the study, while the subdominant bluegreens varied according to season. The number of individuals in all zones was greatest in the summer and lowest in the winter. An examination of the structure of the five edaphic communities indicated a single, nearly homogeneous community exists over the entire surface of the marsh shaded by a angiosperm canopy. Light intensity appears to be the major factor affecting the distribution of bluegreen algae in this salt marsh.     

THE EFFECT OF SULFIDE ON THE BLUEGREEN ALGAE OF HOT SPRINGS. I. NEW ZEALAND AND ICELAND1

The concentration of soluble sulfide (H₂S, HS^?, S⁼)² in hot springs of New Zealand and Iceland has a “species-determining” effect which appears to override the effect of all other chemical factors excepting hydrogen ion concentration. The cosmopolitan high-temperature form (HTF) of Mastigocladus laminosus (Ag.) Cohn appears to be sensitive to concentrations of S⁼ over 0.15 mg·l^?1 in New Zealand and 0.25 mg·l^?1 in Iceland. It was absent in thermal streams where S⁼ level was high enough to exceed this concentration at a point below its optimal temperature range (i.e., below ca. 50 C). In low or non-S⁼ springs in these regions this alga formed mats to an upper temperature limit of 63–64 C. In contrast, one bluegreen alga (Oscillatoria amphigranulata van Goor) occurred abundantly only in moderate to high S⁼ springs of New Zealand; this was a species with an upper temperature limit of about 57 C. Field ¹⁴C-HCO₃^? incorporation experiments with various levels of added S⁼ confirmed the sensitivity of HTF Mastigocladus and the great tolerance of O. amphigranulata. In the latter, the photosynthetic incorporation of ¹⁴C-HCO₃^? was sustained or enhanced by the additions of S⁼ in the presence of 5 × 10^?5m DCMU, an inhibitor of photoelectron transport on the reducing side of photosystem II. It is possible, but not proven, that S⁼ may act as a photoreductant in this species.     

SIDEROCHROMES IN CYANOPHYCEAE: ISOLATION AND CHARACTERIZATION OF SCHIZOKINEN FROM ANABAENA SP.1

Schizokinen, a high affinity iron transport compound (siderochrome), previously described from Bacillus megaterium, has been isolated and characterized from low-iron cultures of a bluegreen alga, Anabaena sp. No conclusive evidence for production of an iron-repressible hydroxamate or catechol type siderochrome was observed in certain other bluegreen algae, such as Anabaena cylindrica Lemm., Coccochloris peniocystis (Kütz.) Drouet & Daily, Anacystis sp., Gloeocapsa alpicola (Lyng.) Born. or Chroococcus sp.     

ACUTE TOXICITY OF SOME BLUEGREEN ALGAE TO THE PROTOZOAN PARAMECIUM CAUDATUM1

Four species of bluegreen algae were tested for possible effect on the protozoan Paramecium caudatum Ehrenberg. Toxicity was demonstrated using lyophilized cells of Fischerella epiphytica Ghose and Gloeotrichia echinulata (Smith) Richter. Nostoc linckia (Roth) Bornet & Thuret failed to show any effects when lyophilized but became toxic when sonified. Anabaena flos-aquae (Lyngb.) Bréb. was nontoxic in all tests. G. echinulata was lethal at 0.1 mg·ml^?1 which is comparable to the toxic concentration of Aphanizomenon flos-aquae (L.) Ralfs reported for microcrustaceans.     

OCCURRENCE OF TRI-LAMELLAR BODIES IN ISOLATES OF NOSTOC (CYANOPHYCEAE)1

Tri-lamellar bodies were observed in eight of 29 isolates of Nostoc examined. They appeared identical to the previously described bodies in various species of Anabaena. The bodies consist of three discoid lamellae each ca. 0.3 μm diam and 8 nm thick. The outer lamella (closest to the plasma membrane) is separated from the middle lamella by a 12 nm space whereas the middle and inner lamellae are ca. 8 nm apart. Osmiophilic striations 3 nm wide were generally observed running between the lamellae. Osmiophilic β granules were usually associated with the inner lamella. The bodies were most always located close to the plasma membrane along the longitudinal wall near the junction of the cross and longitudinal walls. In three isolates the bodies located near the cross walls were associated with gas vesicles and possessed a slightly different morphology. These tri-lamellar bodies consisted of three discoid lamellae, each ca. 2 nm thick, ca. 25 nm apart with electron dense material between the inner and middle lamellae. Pores 20 nm diam and ca. 60 nm apart were observed in layer 2 of the cell wall adjacent to the tri-lamellar bodies. These wall pores were also observed in isolates lacking tri-lamellar bodies.     

PHOTOSYNTHESIS IN THE SNOW: THE ALGA CHLAMYDOMONAS NIVALIS (CHLOROPHYCEAE)1

Red blooms of snow algae consisting almost exclusively of large spherical red cells of Chlamydomonas nivalis (Bauer) Wille are widespread during the summer in the Beartooth Mountains in Montana and Wyoming. Field studies designed to examine the effects of temperature, light, and water potential on algal activity were performed with natural populations using photosynthetic ¹⁴C-HCO₃- or ¹⁴CO₂ incorporation as a measure of activity. The algae photo-synthesized optimally at 5.4 × 10⁴ lx, but were not inhibited by increased light intensity up to 8.6 × 10⁴ lx, the maximum observed in the field. Photosynthesis was sensitive to a reduction in water potential, and since low water potentials develop in snow at temperatures below 0 C, it is unlikely that significant algal activity occurs at the sub-0 temperatures which occur throughout winter. Photosynthesis was much lower following melting of the snow, but this was probably due to decreased diffusion of CO₂. The optimal temperatures varied considerably among the different algal populations. Most samples photo-synthesized optimally at 10 or 20 C but retained substantial activity at temperatures as low as 0 or -3 C. Exceptional samples photosynthesized optimally at 0 or -3 C. It is proposed that the varied temperature responses reflect the presence of different temperature strains. Taken together, the data suggest that development of the snow algae can occur only during the summer months.     

黑曲霉蛋白酶缺陷突变体的分离和鉴定

对黑曲霉(Aspergillus niger)3.795进行紫外诱变和筛选,获得了胞外蛋白酶缺失的菌株。其中突变株37951、3795123和3795130的生长特性与原株基本相同,胞外蛋白酶的活性明显低于原株,葡萄糖淀粉酶的活性与原株基本相同。突变株3795123和3795130的胞外蛋白酶活性分别为原株的54%和84%,可作为外源基因高效分泌表达的宿主菌。