FREEZE-DRYING OF BLUE-GREEN ALGAE FOR ELECTRON MICROSCOPE STUDIES1

Cultures of Anabaena cylindrica Lemm. and Eucapsis sp. were harvested, freeze-dried, and prepared for electron microscope studies. A comparison of the freeze-dried preparations was made with control specimens not freeze-dried. Fixation and embedding were according to the Ryter and Kellenberger technique. The photosynthelic thylakoids of the freeze-dried cells were more distinct and less distorted than those of the control cells. Freeze-dried Eucapsis sp. cells exhibited a prominent mucous capsule, whereas in the nonfreeze-dried, no such capsule could be discerned.     

THE PRODUCTION OF HYDROGEN PEROXIDE BY BLUE-GREEN ALGAE: A SURVEY1

A survey of 38 axenic isolates of blue-green algae indicated that over half the isolates produced hydrogen peroxide under defined growth conditions. Three kinetic profiles for the formation of hydrogen peroxide, were observed; these are described. The possible site or sites of hydrogen peroxide formation remain unknown.     

TAXONOMIC CONFUSION CONCERNING CERTAIN FILAMENTOUS BLUE-GREEN ALGAE1

Throughout a long history many filamentous bacteria may have been identified in natural collections as blue-green algae. This problem has been especially acute regarding the thermophilic species of hot springs, especially at the higher temperatures. It is suggested that in the absence of pure cultures, the minimal criteria for distinguishing filamentous bacteria from blue-green algae microscopically should be: (1) observation of the chlorophyll fluorescence with a fluorescent microscope and (2) demonstration of light-dependent ¹⁴CO₂ fixation autoradiographically. Pure cultures of a number of filamentous thermophiles have been obtained from habitats at temperatures above 60 C. These cultures resemble microscopically the natural material, grow only heterot rophically, and do not contain chlorophyll.     

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.     

INTERCEPTION OF ATMOSPHERIC FIXED NITROGEN AS AN ADAPTIVE ADVANTAGE OF SCUM FORMATION IN BLUE-GREEN ALGAE1

Scum formation by blue-green algae has been interpreted as a nonadaptive failure of the buoyancy control mechanism and, alternatively, as an adaptive mechanism to reduce inorganic carbon limitation. Data from Lake Valencia, Venezuela, are used to illustrate the principle that scum formers intercept significant amounts of fixed N deposited from the atmosphere at the water surface. Interception of fixed N at the surface can confer a significant selective advantage for populations that are strongly N limited, as in Lake Valencia. This additional adaptive advantage to scum formation may be alternative lo or complementary to the possible relief of carbon limitation.     

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.     

ALGAE AS WATER QUALITY INDICATORS FOR A DYSTROPHIC POND

Information on the population structure of planktonic dinoflagellates is reported in the coral reef-mangrove ecosystem at Pelican Cays, Belize. Six sites examined included: Cat Cay, Douglas Cay, Elbow Cay, Fisherman's Cay, Lagoon Cay and Manatee Cay. A spectacular and rich dinoflagellate taxa including oceanic, coastal and offshore species are illustrated. The presence of oceanic species in the studied cays is an unexpected observation since dinolfagellate assemblages are virtually enclosed within ponds bordered by coral ridges that limits water exchange with the open ocean except during storm events. I am also reporting significant differences in the dinoflagellate associations among the studied cays. Dominant taxa included 16 Proroperidinium species, 11 Gonyaulax species, and ten Ceratium species. Only six planktonic species were harmful. Bloom forming species included Ceratium furca and Gonyaulax polygramma. A much more diverse authotrophic and heterotrophic dinoflagellate population characterizes the Pelican Cays than previously suspected. Some species are reported the first time: Protoperidinium belizeanum sp. nov., P. pyrum Balech, P. steidingerae Balech, P. depressum (Bailey) Balech, and P. divergens (Ehrenberg) Balech. These results demonstrate that the Belizean coral reef-mangrove ecosystem is a delicate and species-rich environment, and as such, should be protected and preserved.     

EVIDENCE FOR THE REPAIR OF OZONE-INDUCED MEMBRANE INJURY

The increase in [¹⁴C]-2-deoxy-D-glucose uptake by leaf discs 24 hr after fumigation was used as a measure of ozone injury to pinto bean leaves (Phaseolus vulgaris). This method showed that the primary leaves were most affected by ozone when plants were 10 to 12 days old, which coincided with the time of maximum leaf necrosis. However, 8-day-old plants, which had no visible leaf injury, still showed a higher uptake rate than controls, indicating that injury occurred at the cellular level. In these younger plants, uptake was shown to return to normal over a 5 day period. Moreover, the rate of this “repair” was retarded by cold or continuous darkness, enhanced by continuous light, and very markedly increased by glucose applied to the leaves. The timing of the glucose application was not critical, nor did H₂O or mannitol have an effect. The results suggest that ozone injury at the cellular level can be repaired by energy-dependent processes so that necrosis of the leaf tissue does not occur. These experiments also show that conditions and treatments after ozone exposure can alter the degree of ozone injury.     

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.     

AN IMPROVED METHOD FOR OBTAINING AXENIC CLONES OF PLANKTONIC BLUE-GREEN ALGAE1,2

Axenic clones from 5 isolates of Anabaena flosaquae, 1 isolate of Microcystis acruginosa, and 1 isolate of Aphanizomenon flos-aquae were obtained by a combination of steps that provided a 1000-fold reduction in the bacteria-algae ratio and permitted bacteria-free filaments or cells to be isolated and grown from agar pour plates. The first step consisted of the addition of phenol to a dark-treated culture to selectively reduce the numbers of actively growing bacteria while leaving the resting algal cells viable. The next steps involved washing the treated algal suspension on a Millipore filter pad or membrane followed by plating in washed agar containing buffered mineral medium plus vitamins and soil extract. The final steps consisted of incubating the agar pour plates, coring bacteria-free filaments or cells, culturing the agar cores in a buffered mineral medium, and rigorously testing the resulting cultures for bacteriological contamination. Between 50 and 90% of the cores grew, and of these about 50% were judged axenic. The method, with appropriate adaptations, should be suitable for obtaining axenic clones of other freshwater and marine algae.     

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.     

BLUE-GREEN ALGAE FROM BERMUDA WATERS: ECOLOGICALLY SELECTED VARIATIONS OF A SINGLE SPECIES

Three strains were isolated from Bermuda waters as unialgal cultures. Although identical in cell shape, cell size, and general growth features, marked differences in pigmentation, filament length, and sheath thickness were noted. These differences are explained as being due to differences in physical conditions of the areas of isolation of the 3 strains. It is concluded that the 3 strains are ecologically selected mutants of the single species, Schizothrix calcicola.     

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.     

EXTRACELLULAR INVESTMENTS IN BLUE-GREEN ALGAE WITH PARTICULAR EMPHASIS ON THE GENUS NOSTOC1

The investments of a wide variety of blue-green algae were examined. Many strains formed diffuse slime layers that were unnoticed unless mounted in India ink. Slime occurred in species with and without readily detectable sheaths. The extracellular integument type seemed consistent within strains, although the extent often varied with culture conditions. Experiments with NOSTOC on agar plates indicated that motility was inversely related to the amount of slime present. Some aspects of behavior were related to the nature of an alga's investment.     

EFFECT OF LYSOZYME (MURAMIDASE) ON MARINE AND FRESHWATER BLUE-GREEN ALGAE1

Marine blue-green algae, Lyngbya Lagerheimii, Microcoleus chthonoplastes, Plectonema terebrans, Agmenellum quadruplicatum, and freshwater blue-green algae, Anacystis nidulans, Anabaena variabilis, Nostoc muscorura, and Oscillatoria sp. treated with lysozyme (muramidase) formed spheroplasts but not protoplasts. The time needed for spheroplast induction varied with the species. Approximate internal osmotic pressures of the blue-green algae were determined. Marine algae generally had a higher osmotic pressure than freshwater algae.     

ENERGY EXPENDITURE FOR GLIDING MOTILITY IN A BLUE-GREEN ALGA1

The energy required to overcome viscous drag in a gliding trichome of a blue-green alga advancing and rotating through a medium of known viscosity (67 poise at 25 C) has been calculated to be about 0.05% of the energy available from oxidative phosphorylation (based on respiration measurements), whereas 0.2–5% are possible figures for the amount actually expended. These values represent a low energy demand for a function of probable high survival value, but are comparable to estimates for motility in flagellated cells.     

SPERMATOPHORE SIZE IN BUSHCRICKETS: COMPARATIVE EVIDENCE FOR NUPTIAL GIFTS AS A SPERM PROTECTION DEVICE

During courtship and copulation, males of many insect species provide the female with a nuptial gift of a prey item or synthesized material. These gifts may be explained as a form of paternal investment by increasing female reproductive output, or in terms of mating effort by increasing male fertilization success. These explanations, while not mutually exclusive, are controversial. While experimental studies examine the maintenance of nuptial gifts in single species, comparative studies are required to indicate more general evolutionary trends. Male bushcrickets provide females with a nuptial gift, a spermatophylax, which is transferred to females at mating along with the sperm-containing ampulla. Analysis of comparative data of 28 species of bushcrickets (Orthoptera: Tettigoniidae), reveals that male spermatophore size (spermatophylax and ampulla weight) is positively correlated with female refractory period, which, in turn, correlates with male fertilization success. Moreover, gift size (the spermatophylax) covaries with ejaculate size (the ampulla), which is consistent with the hypothesis that it serves as a sperm protection device. In contrast, there is no significant correlation between any measure of female fecundity and male spermatophylax size. This indicates that the variation in spermatophore size among bushcrickets is better explained by a mating-effort function than a paternal investment function.