bluuebunny/crossref_metadata_2025 huggingface dataset:
Susceptibility of gnotobiotic transgenic mice (Tgϵ26) with combined deficiencies in natural killer cells and T cells to wild-type and hyphal signalling-defective mutants of Candida albicans
Authors: Westwater Caroline , Balish Edward , Warner Thomas F. , Nicholas Peter J. , Paulling Emily E. , Schofield David A.
Published: August 2007

Germfree transgenic epsilon 26 mice (Tgϵ26), deficient in natural killer cells and T cells, were colonized (alimentary tract) withCandida albicanswild-type or each of two hyphal transcription factor signalling mutant strains (efg1/efg1,efg1/efg1 cph1/cph1). EachCandidastrain colonized the alimentary tract, infected keratinized gastric tissues to a similar extent, and induced a granulocyte-dominated inflammatory response in infected tissues. Both wild-type and mutant strains formed hyphaein vivoand were able to elicit an increase in cytokine [tumour necrosis factor alpha, interleukin (IL)-10 and IL-12] and chemokine (KC and macrophage inflammatory protein-2] mRNAs in infected tissues; however, administration of the wild-type strain was lethal for the Tgϵ26 mice, whereas the mice colonized with the mutant strains survived. Death of the Tgϵ26-colonized mice appeared to be due to occlusive oesophageal candidiasis, and not to disseminated candidiasis of endogenous origin. In contrast, the mutant strains exhibited a significantly reduced capacity to infect (frequency and severity) oro-oesophageal (tongue and oesophagus) tissues. Therefore, the two hyphal signalling-defective mutants were less able to infect oro-oesophageal tissues and were non-lethal, but retained their ability to colonize the alimentary tract with yeast and hyphae, infect keratinized gastric tissues, and evoke an inflammatory response in orogastric tissues.
Invasive infection with Streptococcus iniae in Taiwan
Authors: Sun Jun-Ren , Yan Juh-Cheng , Yeh Ching-Ying , Lee Shih-Yi , Lu Jang-Jih
Published: August 2007

Streptococcus iniae, a common fish pathogen, rarely infects humans. In this report, a case of invasive S. iniae infection in a 51-year-old woman with diabetes mellitus and hepatitis C-related liver cirrhosis is described. The isolate was identified by 16S rDNA sequencing. The patient recovered after 1 week of treatment with ampicillin.
The Pan-AC assay: a single-reaction real-time PCR test for quantitative detection of a broad range of Aspergillus and Candida species
Authors: Bašková Lenka , Landlinger Christine , Preuner Sandra , Lion Thomas
Published: August 2007

In view of the growing incidence and the high mortality of invasive aspergillosis and candidiasis, adequate diagnostic techniques permitting timely onset of treatment are of paramount importance. More than 90 % of all invasive fungal infections in immunocompromised individuals can be attributed to Candida and Aspergillus species. To date, standardized techniques permitting rapid, sensitive and, no less importantly, economic screening for the clinically most relevant fungi are lacking. In the present report, a real-time quantitative PCR assay, developed for the detection of the most common pathogenic Candida and Aspergillus species, is described. The single-reaction PCR assay targets a judiciously selected region of the 28S subunit of the fungal rDNA gene. The unique design of the universal primer/probe system, including a pan-
Aspergillus and pan-
Candida (Pan-AC) hydrolysis probe, facilitates the detection of numerous Aspergillus species (e.g. Aspergillus fumigatus, Aspergillus
flavus, Aspergillus
niger, Aspergillus
terreus, Aspergillus
versicolor and Aspergillus
nidulans) and Candida species (e.g. Candida
albicans, Candida
glabrata, Candida krusei, Candida
tropicalis, Candida
parapsilosis, Candida
kefyr, Candida
guilliermondii, Candida lusitaniae and Candida
dubliniensis). The assay permits highly reproducible detection of 10 fg fungal DNA, which corresponds to a fraction of a fungal genome, and facilitates accurate quantification of fungal load across a range of at least five logs. Upon standardization of the technique using cultured fungal strains, the applicability in the clinical setting was assessed by investigating a series of clinical specimens from patients with documented fungal infections (n=17). The Pan-AC assay provides an attractive and economic approach to the screening and monitoring of invasive aspergillosis and candidiasis, which is readily applicable to routine clinical diagnosis.
Endotoxin contamination in the dental surgery
Authors: Huntington M. K. , Williams J. F. , Mackenzie C. D.
Published: August 2007

Dental waterlines contain large numbers of Gram-negative bacteria. Endotoxin, a component of such organisms, has significant health implications. Paired samples of dental unit water and the aerosols generated during dental procedures were collected, and assayed for bacteria and endotoxin levels, using heterotrophic plate counts and theLimulusamoebocyte lysate test. Consistent with published studies, the extent of bacterial contamination in the dental waters sampled for this investigation surpassed the levels associated with potable water, with counts in excess of 2.0×106c.f.u. ml−1in some samples. Correspondingly high concentrations of endotoxin [up to 15 000 endotoxin units (EU) ml−1] were present in the water. A statistically significant Spearman correlation coefficient ofρ=0.94 between endotoxin (EU ml−1) and bacterial load (c.f.u. ml−1) was demonstrated. All of the aerosol samples contained detectable endotoxin. Further studies of the consequences of dental endotoxin exposure, and evaluation of means to prevent exposure, are warranted.
Molecular characterization of serogroup C Neisseria meningitidis isolated in China
Authors: Zhang Xiaobing , Shao Zhujun , Yang E , Xu Li , Xu Xingye , Li Machao , Ren Jun , Zhu Yafang , Yang Fan , Liang Xiaofeng , Mayer Leonard W. , Xu Jianguo , Jin Qi
Published: August 2007

An increase in the number of serogroup C meningococcal disease cases occurred in China from September 2003 to January 2006 as a result of several successive outbreaks. In addition, the proportion of serogroup C Neisseria meningitidis isolates from sporadic cases and carriers has also increased. In this study, 113 serogroup C meningococcal isolates were characterized by multilocus sequence typing (MLST) and PorA typing. These isolates comprised those from outbreak cases and their close contacts, the national carriage survey conducted during the same period and some historical isolates from 1966–2002. Twenty MLST sequence types (STs) and 21 PorA variable region (VR) types were identified in the collection. The ST-4821 complex, a newly identified lineage, was the most prevalent lineage (95/113). These data also showed a high level of diversification of serogroup C isolates, as indicated by the number of variants of the ST-4821 clone and the VR types present. There were ten PorA VR types among the ST-4821 isolates, and certain VR types (P1.7-2,14, P1.12-1,16-8) were associated with isolates from outbreak cases. The results of this study allow us to draw a profile of the molecular characteristics of serogroup C strains in China. These data are helpful for monitoring the spread of virulent strains and will provide valuable information for the prevention of bacterial meningitis in China.
Sequential multiplex PCR for identifying pneumococcal capsular serotypes from south-Saharan African clinical isolates
Authors: Morais Luis , Carvalho Maria da Glória , Roca Anna , Flannery Brendan , Mandomando Inacio , Soriano-Gabarró Montserrat , Sigauque Betuel , Alonso Pedro , Beall Bernard
Published: August 2007

A serial multiplex PCR approach was reformulated for pneumococcal serotyping to test 153 clinical isolates from children in Mozambique. This approach identified serotypes in 139 (90.8 %) of 153 isolates; 126 (82.4 %) were identified within two reactions. This approach in developing countries would require minimal training and could provide useful serotype information without requiring transport of specimens.
CHARACTERISTICS OF PHOSPHORUS DEFICIENCY IN ANABAENA1
Authors: Healey F. P.
Published: August 2007

Several aspects of the metabolism and composition of a strain of Anabaena have been studied during phosphorus deficiency. The effects of medium composition, substrate concentration, temperature, pH, and illumination on alkaline phosphatase activity and phosphate uptake have been examined. Of particular interest among these results was the dependence of maximum alkaline phosphatase activity on Ca and of phosphate uptake on Mg. Depletion of dissolved phosphate from the culture medium runs accompanied by a marked increase in alkaline phosphatase activity, initial rate of phosphate uptake, and total amount of phosphate taken up to satisfaction of the phosphorus debt. Readdition of phosphate to a phosphorus‐deficient culture resulted in a rapid decline in the ability to take up phosphate but no loss of alkaline phosphatase beyond dilution of activity already present. Entry into phophorus deficiency was accompanied by a loss of heterocysts, a decline in chlorophyll a, protein, RNA, and cellular phosphorus, and an increase in carbohydrate per unit dry weight. The possible use of these changes as physiological indicators of phosphorus limitation in natural situations is discussed.
THE FINE STRUCTURE OF THE NUCLEUS AND NUCLEAR ASSOCIATIONS OF DEVELOPING CARPOSPORANGIA IN POLYSIPHONIA NOVAE‐ANGLIAE (RHODOPHYTA)1
Authors: Wetherbee Richard , Wynne Michael J.
Published: August 2007

A high degree of activity of the nuclei in the developing carposporangia of the red alga Polysiphonia novae‐angliae Taylor is described. Profiles of the nucleus are greatly convoluted, resulting in a much increased surface area. Regions where endoplasmic reticulum substitutes for the nuclear envelope are frequently observed. Various cytoplasmic reserves are associated with the nucleus during carposporangium maturation. Lipid bodies, fibrillar bodies, and striated vesicles (or cylindrical bodies) may occur within the nucleoplasm beneath areas of the nuclear envelope substituted by ER. Granules of Floridean starch are observed in proximity to the outer surface of these same areas as well as the nuclear membrane. The homologous nature of the nuclear envelope with the ER is stressed. The role of the nucleus as being actively involved in the synthesis of materials is suggested.
THE PRODUCTION OF HYDROGEN PEROXIDE BY BLUE‐GREEN ALGAE: A SURVEY1
Authors: Stevens S. E. , Patterson C. O. Pat , Myers Jack
Published: August 2007

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.
CALCIFICATION AND ITS INHIBITION IN COCCOLITHOPHORIDS1,2
Authors: Dorigan Janet L. , Wilbur Karl M.
Published: August 2007

The protein synthesis inhibitors cycloheximide and chloramphenicol and the transport inhibitors LaCl3, oligoniycin, and ethacrynic acid were found to inhibit reversibly calcium uptake, coccolith formation, and cell division in the coccolithophorid Cricosphacra (Hymenomonas) carterae. With some, compounds, recovery of calcification was retarded, and in the case of oligomycin, incomplete. Glycerol, 0.5 M, partially reversed the inhibitory effect of chloramphenicol on calcification but not on division. Ouabain was without significant effect on calcium uptake but slowed division in 3 of 5 experiments. Ruthenium red inhibited, neither calcification nor division. In the absence of light, calcification did not occur.
THE POSSIBLE OCCURRENCE OF PHOTOSYNTHETIC MICROORGANISMS IN DEEP‐SEA SEDIMENTS OF THE NORTH ATLANTIC1,2,3
Authors: Malone T. C. , Garside C. , Anderson R. , Roels O. A.
Published: August 2007

An assemblage of 12 diatom species and other photosynthetic microorganisms associated with red clay sediments collected from a depth of 6150 m in the North Atlantic was observed to bloom in Antarctic bottom water when exposed to sunlight at sea surface temperature. Although no growth could be detected over the first 3 days of the experiment, nitrate was nearly completely stripped from the water. The maximum growth rate of 4.7 doubling/day was reached between days 4 and 5. Most of the diatom species have been described as littoral or coastal forms, and it is suggested that these organisms are transported to depth by fecal material, turbidity currents, or a combination of the two.
EFFECT OF LIGHT INTENSITY AND GLYCEROL ON THE GROWTH, PIGMENT COMPOSITION, AND ULTRASTRUCTURE OF CHROOMONAS SP.1,2,3
Authors: Faust Maria A. , Gantt Elisabeth
Published: August 2007

Growth of Chroomonas sp. increased with light intensity (100, 1800, and 2700 μW/cm2) with a fivefold increase from the lowest to the highest intensity. Chlorophyll and phycocyanin content per cell were greater in cells grown at low light intensity, but the ratio of chlorophyll a and c did not vary appreciably. Cells grown at low light intensity had 30% more phycocyanin than cells grown at high intensities of light. The chloroplast of cells with the higher phycocyanin content had average intrathyla‐koidal widths of 300 Å, whereas those cells with the lower phycocyanin content had average intrathylakoidal widths of 200 Å. This result is compatible with the hypothesis that phycocyanin is located in the intrathylakoidal space in the cryptophyte algae. Of the various energy sources tested, only glycerol was able to support limited growth tinder nonphotosynthetic conditions. Under no condition was the chloroplast reduced to an elioplast or proplastid state. Starch accumulation was greatest in cells grown in continuous while light in glycerol. Eye‐spots were commonest in cells grown in darkness and interrupted every 24 hr by a few seconds of white light. It was concluded that this organism is an obligate phototroph.
BACTERIA‐ASSIMILABLE ORGANIC COMPOUNDS, PHOSPHATE, AND ENHANCED GROWTH OF BACTERIA‐ASSOCIATED BLUE‐GREEN ALGAE1
Authors: Lunge Willy
Published: August 2007

The complexities of algal physiology and nutrition make it likely that diverse and often substantial nutrient limitations will be required to control eutrophication in different situations. In defense of a policy exemplified by the generalization “phosphorus is the primary limiting nutrient in most lakes,” Schindler of the Canadian Freshwater Institute has misquotated the work of Lange. Key points of Lange's conclusions are properly quoted, and the reader is cautioned against an oversimplification of a single approach to algal control.
CHARACTERIZATION OF BLEACHING IN CHLORELLA INDUCED BY SUBOPTIMAL GROWTH TEMPERATURES1
Authors: Marvin James W. , Karlander Edward P.
Published: August 2007

Incubation of cultures of a high‐temperature strain of chlorella at 10 C stopped growth and bleached all chlorophyll in the cells in 24 hr. Optimal conditions of light (3.0 mw/cm2), gas (1% CO2‐in‐air), and inorganic medium for maximal growth at 39 C were maintained in the transfer from 39 to 12, 10, or 5 C. The bleaching process at 10 C is characterized by a lag period for the first few hours followed by a linear decrease in chlorophyll content of cultures. The amounts of time required to bleach half of the chlorophyll initially present (effective half‐times) at 10 C were 14 hr for chlorophyll a and 17 hr for chlorophyll b. Effective half‐times of bleaching for total chlorophyll were 47 hr at 12 C and 6 hr at 5 C.

Addition of glucose to inorganic medium delayed but did not prevent bleaching. Use of argon gas instead, of 1% CO2‐in‐air prevented cells from bleaching in both inorganic and glucose media, and indicated an oxygen requirement for bleaching.

Incubation of 6 additional strains of Chlorella at 10 C resulted in responses ranging from bleaching to no growth to growth.
SCENEDESMUS MORPHOGENESIS. COLONY CONTROL IN DILUTE MEDIA1
Authors: Trainor F. R. , Shubert L. E.
Published: August 2007

Morphological stability, with the elimination of the unicellular singe, was achieved by culturing several strains of Scenedesmus in media with, low inorganic salt levels. Organisms stabilize and form only colonies at specific nutrient levels. One became colonial only when the salt level was dropped to 3.07 mg inorganic salts per liter, with N and P at levels found in nature.
THE EXTRACELLULAR RELEASE Of GLYCOLIC ACID BY A MARINE DIATOM1
Authors: Smith Walker O.
Published: August 2007

The excretion of glycolic acid by the marine diatom Chaetoceros socialis through time was studied. Excretion in axenic cultures was linear for the time intervals used, but for nonaxenic cultures an equilibrium was created, suggesting bacterial uptake of glycolic acid. In studies with an inhibitor of glycolate dehydrogenase, the level of glycolic acid in the medium jumped 15–fold. This shows the presence of this enzyme, and implies the presence of the entire set of enzymes which convert glycolic acid to serine and release carbon dioxide. In both axenic and nonaxenic cultures a steady state was reached. All of the data suggest that at high cell densities glycolic acid is liberated from the cell by a passive mechanism. The effect of such an excretion in natural waters is discussed.
MORPHOLOGY AND NUTRITION OF PANDORINA UNICOCCA SP. NOV.1,2
Authors: Rayburn William R. , Starr Richard C.
Published: August 2007

Eleven strains of Pandorina unicocca sp. nov. were studied for morphological characterization. The species was delimited by having cells which contain a single basal pyrenoid and by colonies which have cells separate from each other in the colonial envelope. A defined medium was developed for 4 strains of P. unicocca and the nutritional requirements of these strains were examined. All 4 strains were capable of completely autotrophic growth and they could utilize nitrate, ammonium, or urea as nitrogen sources. Optimum growth was nuts attained at pH 8.0.
COMPARATIVE PHYSIOLOGY AND MORPHOLOGY OF SIX STRAINS OF STIGONEMATACEAN BLUE‐GREEN ALGAE1
Authors: Martin Thelma C. , Wyatt J. T.
Published: August 2007

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.
CALCIUM DEFICIENCY CAN INDUCE THE TRANSITION FROM OVAL TO FUSIFORM CELLS IN CULTURES OF PHAEODACTYLUM TRICORNUTUM BOHLIN1,2
Authors: Cooksey Keith E. , Cooksey Barbara
Published: August 2007

The diatom Phaeodactylum tricornutum Bohlin is known to be pleomorphic. Previously it was considered that growth on medium solidified with agar produced ovate cells, whereas growth in liquid medium gave rise to fusiform cells. We have shown that ovate cells can be propagated in liquid medium if the calcium content of the medium is below 15 mg/liter. If the concentration of calcium is raised, fusiform cells develop.
STRUCTURE OF THE PERIPLAST OFCRYPTOMONAS OVATAVAR.PALUSTRIS1,2
Authors: Faust Maria A.
Published: August 2007

The periplast ofCryptomonas ovatavar.palustrisis composed of polygonal plates which are delineated by shallow ridges. A small ejectosome is located at each corner of the plate area. The plate areas vary in size; they are smallest at the anterior and posterior ends and are largest in the middle of the cell with an average length of 0.5 μ and of width 0.4 μ. In cross section a plate area is composed of 2 distinct layers, an outer plasma membrane layer with a fine particulate, appearance, and an inner layer consisting of two sheets. The sheets of the inner layer have a striated lattice pattern with a periodicity of about 20 nm. In negatively stained preparations one lattice appears to underlie another at certain angles. Protease digestion removed polygonal shaped inner layer.
THE ULTRASTRUCTURE OF CARPOSPOROGENESIS IN THE MARINE HEMIPARASITIC RED ALGAERYTHROCYSTIS SACCATA1
Authors: Kugrens Paul , West John A.
Published: August 2007

The ultrastructure of carposporogenesis forErythrocystis saccatais described. The fusion and gonimoblast cells contain few organelles, and chloroplasts are in a proplastid state, with pit plugs between gonimoblast cells dissolving early in development. Carpospore development may be separated into 3 stages, the first stage being characterized by the appearance of straight‐profiled dictyosomes, fibrous vesicles, and an increase of discoid thylakoids within the chloroplasts. During the second, stage the dictyosomes assume a curved profile and striped vesicles are formed by the endoplasmic reticulum. The third stage is initiated by the disappearance of striped vesicles and the appearance of straight‐profiled dictyosomes secreting vesicles with cores. Mature carpospores consist of many cored vesicles, fibrous vesicles, and floridean starch grains. A single wall layer surrounds each carpospore since the carposporangial wall becomes incorporated into a mucilaginous matrix surrounding the spores.
SPORANGIAL STRUCTURE AND ZOOSPOROGENESIS IN CHORDA TOMENTOSA (LAMINARIALES)1,2,3
Authors: Toth Ronald
Published: August 2007

Members of the genus Chorda represent the simplest form of sporophyte in the order Laminariales. The present study deals with reproduction in Chorda tomentosa, involving the initiation, growth, and structure of the sporangium and the process of zoosporogenesis. The simple tube‐like sporophyte of Chorda tomentosa grows in diameter by means of repeated anticlinal divisions in a superficial meristematic layer known as the meristoderm. The onset of reproduction is marked by the conversion of the meristoderm from contributing cells to the vegetative plant body to producing 2 new cell types: paraphyses and sporangial mother cells. At the time of initiation, sporangial mother cells are crescent shaped and possess a densely staining cytoplasm. Sporangial mother cells increase in size, become ellipsoid, decrease in staining density, and undergo meiosis. After meiosis, sporangia increase in size while their nuclei undergo successive cycles of synchronous mitotic divisions. Sporangia increase to a maximum length of 120 μ;m at which time they possess the characteristic “cap” found in all members of the order studied thus far. At this stage the protoplast of the sporangium is organized into a peripheral layer of nucleus‐chloroplast pairs and a central region of vacuoles. Cleavage furrows begin to form at the cell membrane and are met by furrows developing in the interior of the cytoplasm resulting in the division of the entire protoplast into separate units. Each unit is an individual zoospore. The biflagellate zoospores contain a nucleus, one chloroplast with eyespot, perinuclear Golgi, and several bodies of presumed storage carbohydrate. The occurrence of a small population of early developing sporangia is described. In essential details, the origin, development, and structure of sporangia in Chorda tomentosa are identical to all earlier observations in the Laminariales.
PHYCOLOGICAL NOTES. III. TWO NEW SACCATE UNICELLULAR CHLOROPHYCEAE1
Authors: Bold Harold C. , MacEntee Frank J.
Published: August 2007

Comparative study, under standard conditions of growth in a variety of media, of 2 unicellular chlorophycean algae living in soil, both of which produce spherical and saccate cells in their development, has resulted in the description of 2 new taxa, Ascochloris multinucleata gen. et sp. nov., Chlorococcaceae, Chlorococcales, and Ignatius tetrasporus gen. et sp. nov. of the Chlorosarcinaceae, Chlorosarcinales.
CHLOROPLAST STRUCTURE AND PIGMENT COMPOSITION IN THE RED ALGA GRIFFITHSIA PACIFICA: REGULATION BY LIGHT INTENSITY1
Authors: Waaland J. Robert , Waaland Susan D. , Bates George
Published: August 2007

The ratio of accessory phycobiliproteins to chlorophyll a is controlled by light intensity in the marine red alga Griffithsia pacifica. The greatest changes in pigment ratios are observed below 300 ft‐c; above 300 ft‐c the response approaches saturation. Ultrastructural examination of chloroplasts of plants grown at different intensities reveals that the number of phycobilisomes per unit of photosynthetic thylakoid changes in direct proportion to the pigment ratios and in inverse proportion to the light intensity.
EXTRACELLULAR INVESTMENTS IN BLUE‐GREEN ALGAE WITH PARTICULAR EMPHASIS ON THE GENUS NOSTOC1
Authors: Martin Thelma C. , Wyatt J. T.
Published: August 2007

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.
A SEASONAL DIATOM IN A FROZEN WISCONSIN LAKE1
Authors: Boylen Charles W. , Brock Thomas D.
Published: August 2007

An extensive bloom of a stalked diatom, Cymbella sp., developed under the ice in Lake Wingra, a hard‐water lake in southern Wisconsin. The diatoms were attached to decomposing plants of Myriophyllum spicatum L. Uptake of H14CO3− showed the Cymbella to have an optimum temperature for carbon fixation of 25 C throughout the winter. Microscopic examination of samples taken from January through April showed Cymbella to dominate all other eucaryotic organisms. It is concluded that despite the fact this organism predominates in this winter habitat, it does not become optimally adapted to the temperature of its environment.
POLYMORPHISM IN THE DESMID MICRASTERIAS PINNATIFIDA AND ITS TAXONOMICAL IMPLICATIONS1
Authors: Sormus Laine , de Mattos Bicudo Carlos Eduardo
Published: August 2007

A case of polymorphism in the desmid Micrasterias pinnatifida (Kütz.) Ralfs is described. It is based on material collected from the overflow channel of a dam in Caeté, Minas Gerais State.

After careful examination of nearly 500 specimens, 26 different morphological expressions of the alga were found which led the authors to make the following deductions: (1) for delimitation of species and infraspecific taxa in desmids it is absolutely necessary to analyze sample populations; (2) the morphological characteristics presently used, for delimination of some varieties of M. Pinnatifida (Kütz.) Ralfs seem to have no taxonomical value if only isolated individuals are examined; (3) the varieties granulata, inflata, and tridentata must be considered with some caution, until further studies are carried out, because they can be merely distinct morphological expressions of M. pinnatifida (Kütz.) Ralfs var. pinnatifida.
GROWTH OF TWO FACULTATIVELY HETEROTROPHIC MARINE CENTRIC DIATOMS1,2
Authors: White Alan W.
Published: August 2007

The facultative, heterotrophs Cyclotella cryptica (sclone WT‐1‐8) and Coscinodiscus sp. were selectively isolated from coastal waters by dark incubation of organically enriched solid medium. C. cryptica grows in the dark with glucose and galactose, and Coscinodiscus sp. with glucose. Clone WT‐1‐8 of C. cryptica grows about twice as fast with glucose as a previously studied clone (0‐3A). In the dark with, 5 × 10−6 M glucose C. cryptica divides every 3 days, while with 5 × 10−5 M glucose Coscinodiscus sp. divides every 10 days. Heterotrophic growth of either diatom for 1 year does not cause a major reduction in carbon, nitrogen, chlorophyll a, and chlorophyll c contents, or in photosynthetic ability, compared to light‐grown cells. It is possible that facultative heterotrophy is of ecological benefit to these diatoms, probably for slow growth and survival during extended periods of dim light or darkness.
MICROMORPHOLOGY OF A SMALL DINOFLAGELLATE PROROCENTRUM MARIAE‐LEBOURIAE (PARKE & BALLATINE) COMB. NOV.1,2,3
Authors: Faust Maria A.
Published: August 2007

The surface structures of the bivalvate dinoflagellate Prorocentrum mariae‐lebouriae are described in detail. It has an almost spheroidal shape in face‐view, a compressed saucer‐shape in side view, with a distinct striated band at the edge of the cell. Its surface is covered with small spines in a regular pattern, with 450 nm distance between pairs. The spines are 100–120 nm wide and 200–300 nm long. There are 600–700 spines on each valve. At the anterior cell end, one of the values has a V‐shaped depression which contains a specialized structure accommodating the 2 flagellar pores. The flagellar pores are‐enclosed by 8 small, thick plates held together and to the values by sutures. The flagellar pore area consists of 2 distinct structures: an apical collar possessing a curved forked plate and a larger structure composed of an unbranched, plate. There are 2 flagellar canals located between the flagellar pore plates. Beneath each flagellar canal lies a row of 11 microtubules. A row of microtubules forming a microtubular cylinder is situated adjacent to the oblong flagellar canal near a simple pusule. The microtubular cylinder encircles electron dense bodies. The bases of the longitudinal and transverse flagella appear to lie at an angle to each other. The above features are illustrated with transmission and scanning electron micrographs.
PHYTOPLANKTON DISTRIBUTION AND WATER QUALITY INDICES FOR LAKE MEAD (COLORADO RIVER)1
Authors: Staker Robert D. , Hoshaw Robert W. , Everett Lorne G.
Published: August 2007

Phytoplankton samples were collected in Lake Mead 6 times from September 1970 to June 1971 for 8 stations at depths of 0, 3, 5, 10, 20, and 30 m. These samples were processed through a Millipore filter apparatus and 79 planktonic algae were identified. Algal divisions represented were Bacillariophyta, 42 species; Chlorophyta, 18; Cyanophyta, 9; Chrysophyta, 3; Cryptophyta, 3; Pyrrophyta, 2; and Euglenophyta, 2. Blue‐green algae were dominant in late summer and fall; green algae, diatoms, and cryptomonads in winter; and green algae in spring. The early summer flora was best represented by the Chlorophyta, Cryptophyta, and Chrysophyta. Palmer's pollution‐tolerant algae indices and Nygaard's indices were calculated from, phytoplankton data. These indices suggest eutrophic conditions in Lake Mead, especially for Boulder Basin.
CHLAINOMONAS KOLII(HARDY ET CURL) COMB. NOV. (CHLOROPHYTA, VOLVOCALES), A REVISION OF THE SNOW ALGA, TRACHELOMONAS KOLII HARDY ET CURL (EUGLENOPHYTA, EUGLENALES)1,2
Authors: Hoham Ronald W.
Published: August 2007

The snow alga Trachelomonas kolii is transferred from the Euglenophyta (Euglenales) to the Chlorophyta (Volvocales) as Chlainomonas kolii comb. nov. As a result of critical examination of both living and type material, this species was found to have 4 flagella per vegetative cell, true starch, and 1 axial plastid per cell with several peripheral lobes. Vegetative cells of Trachelomonas kolii were described originally as having 1 flagellum, lacking true starch but having paramylum, and as having several parietal plastids per cell. The reticulate markings on the outer envelope of vegetative cells were found to be different from those in the original illustrations.

Vegetative cells and resting spores of Chlainomonas kolii and Chlainomonas rubra are compared. The similarities of resting spores of Chlainomonas kolii and Chlamydomonas nivalis are discussed. These are the first records of Chlainomonas kolii from snow in Washington State.
ENDOCYTOSIS OF MICROCYSTIS AERUGINOSA BY OCHROMONAS DANICA1
Authors: Cole Garry T. , Wynne Michael J.
Published: August 2007

Ochromonas danicaPrings., a chrysomonad alga which demonstrates a high degree of nutritional versatility, is capable of feeding on the toxic blue‐green algaMicrocystis aeruginosaKuetz. In this paper light microscopic, electron microscopic, and cytochemical examinations of endocytosis inO. danicaare reported, with particular emphasis on the vicissitudes of endocytic and lysosomal activities during intra‐cellular digestion. An interpretation of the function of organelles associated with endocytosis is presented.
COMPETITIVE EXCLUSION AMONG THREE PLANKTONIC BLUE‐GREEN ALGAL SPECIES1,2
Authors: Lange Willy
Published: August 2007

Although domination of 1 species in an algal community has often been attributed to toxic effects, nutrient exhaustion can also lead to competitive exclusion among algal species.

The bacteria‐associated blue‐green algae Microcystis aeruginosa, Nostoc muscorum, and Phormidium foveolarum were cultivated in Zehnder‐Gorham's medium No. 11 individually and in their combinations. The growth rates of Microcystis and of Nostoc were reduced by the presence of Phormidium. This detrimental effect was apparently not due to formation of any toxic or allelopathic matter. It was caused by the reduction of iron and trace metal concentrations in the medium by Phormidium to levels too low for normal growth of Microcystis and Nostoc. Work with the axenic forms of the 3 algal species also indicated a lowering of iron and trace element concentrations by Phormidium to levels not sufficient for sustained growth of Microcystis and Nostoc. Thus, bacteria played no significant role in this example of competitive exclusion.
ELECTRICAL IMPEDANCE IN ASCOPHYLLUM NODOSUM AND FUCUS VESTCULOSUS IN RELATION TO COOLING, FREEZING, AND DESICCATION1
Authors: MacDonald Marilyn A. , Fensom D. S. , Taylor A. R. A.
Published: August 2007

Electrical impedance monitoring techniques appear to be useful in tracing the effect of cooling or desiccation upon the thallus of Fucus vesiculosus and Ascophyllum nodosum.

These algae were found to be remarkably resistant to injury from freezing down to −20 C even during midsummer and from desiccation up to 70% water loss, and in these properties were markedly different from land plants.

Freezing point depressions, the degree of supercooling, activation energies of cooling‐impedance curves, and the slope of these curves themselves were useful in disclosing differences between time of sampling, storage time, and indications of damage in tissue. No significant difference could be detected between the 2 species collected and tested at the same time. Significant differences occurred in F. vesiculosus between summer and winter, and in winter between submersed and intermittently exposed plants. Tracer ion uptake techniques confirmed that freezing to −20 C did not kill tissues.
PHOSPHATE UPTAKE UNDER NITRATE LIMITATION BY SCENEDESMUS SP. AND ITS ECOLOGICAL IMPLICATIONS1
Authors: Rhee G‐Yull
Published: August 2007

Under nitrogen limitation the phosphate content of Scenedesmus sp. shows little variation regardless of growth rate and the N/P atomic ratio of the medium. P uptake therefore can be calculated as the product of P content and N‐dependent growth rate. The maximum rate of P uptake in N limitation is lower by a factor of about 8 than the rate in P limitation.

As reported earlier, P uptake by this alga under P limitation is described by the kinetics resembling non‐competitive enzyme inhibition, with one or several intracellular P fractions as inhibitors. These fractions include surplus P (water extractable) and inorganic polyphosphate fractions A (acid soluble) and B, C, and D (acid insoluble). In N limitation, the ratios of fractions A, B, C, and D are quite different from the ratios of P limitation at comparable growth rates. The concentrations of polyphosphate fraction A in N‐limited cells are much, higher than the levels in P‐limited cells, and this fraction becomes more predominant at low growth rates in N limitation. This fraction, if introduced as the inhibitor into the noncompetitive scheme, explains the uptake kinetics in both N‐ and P‐limited cells and the low maximum uptake rate in N limitation.

This finding may have two significant ecological implications: (1) A nutrient imbalance which brings about changes in the internal, level or the metabolism, of fraction A would affect P uptake. (2) Nitrogen sufficiency would cause a competitive advantage in P uptake. This advantage would be shared by N2 fixers and algae with low optimum N/P ratios.

In Scenedesmus sp. P limitation switches to N limitation and vice versa when the cell N/P atomic ratio is about 30.
MODIFICATION OF PHYTOPLANKTON GROWTH BY EXCRETED COMPOUNDS IN LOW‐DENSITY POPULATIONS1
Authors: Huntsman Susan A. , Barber Richard T.
Published: August 2007

Conditioned seawater, removed by filtration from an exponentially growing mixed phytoplankton population, inhibited the growth of a small inoculum of cells from the same source without reducing the lag period. When the 2 populations, one in exponential growth and the other freshly inoculated, were separated by a filter membrane allowing passage of excreted compounds, the growth rate of the freshly inoculated cells was again depressed but the lag phase was reduced almost as effectively as by the addition of the chelator, EDTA. Thus both inhibitory and stimulatory compounds appear to be excreted by the cells during exponential growth, the stimulatory group, apparently involved with trace metal metabolism, being more labile to degradation.

A test was made to determine if the population could be induced to utilize unconditioned water. Even after repeated transfers there was no reduction in the lag period, indicating that the initiation of exponential growth represents a response to excreted conditioning agents (possibly chelating compounds) rather than an adjustment by the population to use unconditioned water.
ADAPTATION OF THE UNICELLULAR ALGA DUNALIELLA PARVA TO A SALINE ENVIRONMENT1
Authors: Ben‐Amotz Ami
Published: August 2007

The holophilic alga Dunaliella parva produces glycerol as a major product of photosynthetic 14CO2 incorporation and accumulates very large amounts of intracellular glycerol. A method was adopted for the determination of the cell water space based on the distribution of 14C sorbitol and 3H2O between the cells and the medium. Using these measurements the internal concentration of glycerol was found to be isoomotic with that of the medium over a broad range of 0.6 to 2.1 m NaCl. When the extracellular salt concentration of an algal suspension was increased or decreased, the intracellular water content immediately varied so as to keep an osmotic equilibrium between the cells and the medium. During the following 90 min under metabolic conditions, glycerol content changed until a new level was reached. Since no leakage of intracellular glycerol was observed above 0.6 m NaCl, these alterations in glycerol content are interpreted as due to metabolic formation and degradation of intracellular glycerol. Determination of the glycerol sensitivity of enzymic and photosynthetic reactions of cell‐free preparations from D. parva showed a broad range of tolerance to high concentrations of glycerol.

These results indicate that osmoregulation in Dunaliella depends on the synthesis or degradation of intracellular glycerol in response to the external salt concentration. A proposed scheme of glycerol synthesis in Dunaliella is suggested.
THE CORRELATION OF GOLGI ACTIVITY AND POLYSACCHARIDE SECRETION IN PORPHYRIDIUM12
Authors: Ramus J. , Robins D. M.
Published: August 2007

Quantitative morphometric measurements were made of the area occupied by the Golgi complex in log and stationary phase cells. The technique involved the cutting out and weighing of cellular compartments from electron micrographs of median cell sections. Data from the morphometric measurements combined with physiological measurements of secretory activity yielded a simple model for the involvement of the Golgi complex in the biogenesis of cell surface polysaccharides. Golgi were larger and more numerous in log phase, perhaps indicating a higher rate of polysaccharide synthesis than in stationary phase. In log phase, polysaccharide‐containing vesicles accumulate adjacent to the cell membrane. In stationary phase, the polysaccharide is secreted to the cell surface by exocytosis, giving rise to a capsule. Thus the shift from log to stationary phase results in structural and functional cellular differentiation, eg, from a thin to a thick capsule. The ecological implications of capsule formation are discussed.
TRANSFORMATION OF NONPOLAR FILAMENTS OF THE BLUE‐GREEN ALGA GLOEOTRICHIA ECHINULATA U. WISC. 1052 INTO DOUBLE HELICES12
Authors: Lange Willy
Published: August 2007

Normally straight filaments of Gloeotrichia echinulata U. Wisc. 1052 transform into double helices when a critical culture density has been attained. In inorganic Zehnder‐Gorham's medium No. 11, the alga initially is morphologically uniform and forms single, lightly curved, polar filaments. When a stage of close proximity of the filaments is reached, excessively long filaments are observed that are nonpolar. Some of these nonpolar filaments form helices. Two independent single helices may entwine to form a double helix. Double helices also form when both ends of an excessively long filament meet and start entwining until a loop is left at about the original middle of the filament. In another manner of double‐helix formation, a straight filament makes a hairpin bend at about its middle; then 2 helices form starting at the bend and they entwine into a double helix, leaving a loop at the location of the original bend. Under proper culture conditions, the structures of double helices show an amazing regularity. Once double‐helix formation has started, some strong force brings the process to completion. In a mature culture, helices disintegrate into apparently healthy, short pieces of filaments or single cells, while the straight or slightly curved polar filaments still persist. Helical transformation of nonpolar filaments does not appear to be a sign of nutritional or other stress but rather appears to serve a specific purpose. One might speculate that a genetic exchange between opposite cells takes place.
DEVELOPMENT AND GERMINATION OF AKINETES OF APHANIZOMENON FLOS‐AQUAE1
Authors: Wildman Ruth B. , Loescher Judith H. , Carol L. Winger
Published: August 2007

Flakes of Aphanizomenon flos‐aquae collected from an ice‐covered lake were found to contain all developmental stages from vegetative cells to mature akinetes. Changes during development include increase in cell size, gradual disappearance of gas vacuoles (clusters of gas vesicles), narrowing of intrathylakoidal spaces, and increase in cytoplasmic density. Development of akinetes is accompanied by proliferation of ribosomes, including polyribosomes, cyanophycin granules (structured, granules), and glycogen granules. The lipid bodies of vegetative cells are reduced in size and number in mature akinetes. Akinetes may occur singly or as multiples in sequence in a filament, either terminal or intercalary. Loss of flotation by increase in cytoplasmic density permits filaments to sink and overwinter in bottom sediments. The sequence was found to be reversed during germination of akinetes. Cyanophycin granules are reduced in size and staining density in the sporelings, and very few glycogen granules are seen. Gas vesicles reappear and increase in number, and intrathylakoidal spaces become wider. These changes then would permit the sporelings to rise from the bottom and begin another season's bloom.
ULTRASTRUCTURE OF THE RESERVOIR AND FLAGELLA IN PHACUS PLEURONECTES (EUGLENOPHYCEAE)1
Authors: Dynesius Roselynn A. , Walne Patricia L.
Published: August 2007

The ultrastructure of the reservoir region of Phacus pleuronectes is described. Thin sections, ruthenium red staining, and shadow‐cast preparations elucidate relationships and structural details of the flagella and flagellar hairs or mastigonemes. A heretofore undescribed structure in Phacus, the multitubular structure (MTS), with associated fibrillar projections, is reported. The MTS is located in the cytoplasm at the distal region of the reservoir near the contractile vacuole. A coordinated function of the MTS and adjacent fibrillar projections is suggested. The occurrence of mastigonemes along the entire length of the emergent flagellum is suggested, in contrast to earlier reports of their presence only on that portion of the flagellum distal to the cytostome. The present investigation postulates also that the mastigonemes are bipartite, the thicker fibrous bases becoming modified distally into the classically described, mastigonemes.
ISOLATION OF NITROSOGUANIDINE‐INDUCED CHLORELLA VULGARIS MUTANTS WITH HIGH METHIONINE CONTENT1
Authors: Cacco Giovanni , Ferrari Giovanni
Published: August 2007

Mutants of Chlorella vulgaris induced by N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (NG), and, selected for the resistance to either ethionine or 6‐methylpurine, were tested for the relative rate of incorporation into protein of 3H‐methionine and 14C‐leucine. A highly significant, correlation between the 3H‐to‐14C ratio in the protein and its methionine content was found. 6‐Methylpurine proved to be more effective than ethionine as a screening agent for high methionine strains. Screening for 6‐methylpurine resistance, followed by a second screening for the highest methionine‐to‐leucine incorporation ratio, led to isolation of the mutants with a content up to 45% higher in methionine and up to 3 times higher in cysteine with respect to the wild strain.
THE ULTRASTRUCTURE OFSCENEDESMUS(CHLOROPHYCEAE). I. SPECIES WITH THE “RETICULATE” OR “WARTY” TYPE OF ORNAMENTAL LAYER1
Authors: Staehelin L. Andrew , Pickett‐Heaps Jeremy D.
Published: August 2007

The ultrastructure of the wall layers and ornamentative features ofScenedesmus pannonicusandS. longusare described using carefully correlated freeze‐etched replicas, thin sections and scanning electron micrographs. The two species arc enclosed by different types of ornamented layers,S. pannonicusby the tightly filling, “warty” layer andS. longusby the loosely fitting, “reticulate” layer, held off the coenobium by 2 types of tubular propping spikelets and rosettes. The reticulate layer has an intricate substructure, especially when studied with freeze‐etching. Its inner and outer surfaces appear different, as is its attachment to the 2 types of spikelets. Whole cells ofS. longussubjected to acetolysis lack the cellulose wall and cytoplasm, but all other surface features survive, including the Trilaminar Sheath (TLS); this ornamentation cannot be “pectic.” The cellulose wall and ornamentation is unaffected by boiling water alone. Boiling in 6nNaOH removes the surface ornamentation, but the TLS and wall remain; the possibility that these features contain silica is discussed.

The terminal spines of both species consist of closely packed spikelets enclosed within a skin of hexagonally‐packed subunits. Similar subunits are seen in the propping spikelets of S. longus, and in the rows or “combs” of laterally fused spikelets ofS. pannonicus.The warty layer ofS. pannonicusis tightly appressed to the TLS except close to where the cells are joined, where it is suspended free. It is composed of a layer of globular subunits, and small indentations form the warts. Single, evenly distributed warts characterize the freely suspended sections of the warty layer, and the layer that encloses young coenobia soon after they have been formed: in contrast, the warts are clumped over the surface of older and larger colonies. Some of the single warts form characteristic double rows, but these latter remain single even on older cells. The surface structure of the warty layer, TLS, and plasmalemma are revealed by the freeze‐etching process.