bluuebunny/crossref_metadata_2025_split huggingface dataset:
MORPHOLOGY AND REPRODUCTION OF THE RED ALGA ACROCHAETIUM PECTINATUM IN CULTURE12
Authors: West John A. 
Published: April 2007

SUMMARY The life history of the marine red alga Acrochaetium pectinatum (Kylin) Hamel was studied in unialgal culture using supplemented natural seawater media. The tetrasporophytes are larger than the gametophytes, have a compact filamentous basal system, and produce monosporangia and tetrasporangia. Mono‐spores give rise to tetrasporophytes. Tetraspores develop into small gametophytes with unicellular bases. The gametophytes are heterothallic when small (usually less than 500 μ) but as some females become larger (2‐3 mm) they produce spermatangia as well as carpogonia. Gametophytes may bear mono‐sporangia in addition to carpogonia or spermatangia. These monospores give rise to gametophytes. Fertilization of the carpogonia has not been observed. The tetrasporophytes produce only monosporangia in day‐lengths of 12‐16 hr, but both tetrasporangia and monosporangia are formed in daylengths of 6–10 hr. Tetrasporangial production is reduced at 15 C compared with 10 C. Light intensity in the range of 5‐200 ft‐c (cool white fluorescent lighting) has no apparent influence on induction of tetrasporangia. Induction of tetrasporangia is not a photoperiodic response because their development is not inhibited by a brief light break in the middle of the dark period in short daylengths. Plastid morphology, origin, and frequency of sporangia and vegetative branching are variable during the ontogeny, and consequently are somewhat unreliable as taxonomic criteria. Differences in basal systems between gametophytes and tetrasporophytes also indicate that this feature, which is used to distinguish major subgeneric groupings in Acrochaetium, may not be as useful as previously thought.
ELECTRON AND PHASE‐CONTRAST MICROSCOPY OF SEXUAL REPRODUCTION IN CHLAMYDOMONAS MOEWUSII1
Authors: Brown R. Malcolm , Johnson Sister Clement , Bold Harold C. 
Published: April 2007

SUMMARY The sexual process of C. moewusii from gametic activation through germination of the zygote has been studied with phase‐contrast and electron microscopy. Long strands emerging from the gametic flagellar tips are the site of early flagellar attraction which is followed by union of compatible flagella within common flagellar sheaths. The gametic connecting strand is formed by coordinated elongation of the plasma papillae of a gametic pair and the penetration of the former through their wall papillae while the flagella are in intimate association. After the free‐swimming period, the gametic pairs aggregate in a second period of clumping. The connecting strand is abscised and extruded during plas‐mogamy as are the flagellar basal bodies. Evidence is presented which suggests union of the gametic plastids, and stages in karyogamy are illustrated. Formation of the wall layers, accumulation of starch and lipids, and changes in plastid organization in the maturing and germinating zygote are described as is the formation of the gonal walls.
DETECTION OF LIMITING OR SURPLUS NITROGEN IN ALGAE AND AQUATIC WEEDS1
Authors: Fitzgerald George P. 
Published: April 2007

SUMMARY The rate of NH4+‐N absorption by algae and aquatic weeds in the dark has been shown to be 4‐5 times greater for plants which are N‐limited as compared to plants with sufficient available N. Eight species of green algae, 2 blue‐green algae, 2 diatoms, and 3 aquatic weeds were used to demonstrate the usefulness of the test in determining if available N was in surplus or limited supply in a particular environment. The test was shown not to differentiate between blue‐green algae capable of fixing N (4 species) from media with NO3‐N or without combined nitrogen. The factors influencing the results of NH4+‐N absorption tests have been investigated. In order to differentiate between plants with sufficient available N and those which are N limited, the rate of NH4+‐N absorption (0.1 mg N) over 1‐hr incubation in the dark by 10‐20 mg of algae or aquatic weed tissues is measured. The relatively simple analysis for NH4+‐N in the samples makes it very easy to follow the changing N nutrition of plants in cultures with a limited N supply or in the presence of possible N sources.
CULTURE AND HETEROTROPHY OF THE FRESHWATER DINOFLAGELLATE, PERIDINIUM CINCTUM FA. OVOPLANUM LINDEMAN1
Authors: Carefoot J. Russel 
Published: April 2007

SUMMARY A defined minimal medium was developed for an axenic strain of Peridinium (Indiana Culture No. LB 1336). Thiamine, biotin, and vitamin B12 did not stimulate growth. Of 15 organic carbon sources tried in light, fructose, galactose, glucose, malate, malonate, and pyruvate enhanced growth but propionate retarded growth. In dark‐grown cultures only media with succinate permitted growth above the survival level. Stimulation of growth by organic carbon sources was markedly pH dependent.
THE BEHAVIOR OF OSCILLATORIA TEREBRIFORMIS IN HOT SPRINGS1
Authors: Castenholz Richard W. 
Published: April 2007

SUMMARYOscillatoria terebriformis, occurring from 54 to about 35 C in eastern Oregon hot springs, forms dense reddish‐brown surface mats which are held together by the interwoven nature of the trichomes and not by a gel‐like matrix, thus retaining the flexibility inherent in free trichome motility. The trichomes demonstrate gliding, flexional, and contractile movements. When the trichomes are interconnected, the mat contracts or retracts essentially as a unit in response to high light intensity (ca. 100 cm/hr) or supraoptimal temperature (ca. 2 cm/hr). Under lower light intensity and optimal temperature, the mat expands by the gliding movements of individual trichomes (1‐3 cm/hr). Probable positive and negative phototopotactic responses of trichomes to low and high light intensities, respectively, also influence the density of the surface mat. Thus, the population of Oscillatoria is able to adjust its position and density rapidly by migrations and contractions, remaining almost always within the full optimal temperature range and fairly well xuithin the optimal light conditions as well.
UPTAKE OF NITRATE AND NITRITE BY DITYLUM BRIGHTWELLII‐KINETICS AND MECHANISMS12
Authors: Eppley Richard W. , Coatsworth James L. 
Published: April 2007

SUMMARYDitylum brightwellii grown on NO2‐ as a nitrogen source took up and assimilated NO2‐ only in the light, apparently via a photosynthetic nitrite reductase. Assimilation was inhibited by dichlorophenyldimethylurea (DCMU), KCN, partially by 2,4 dinitrophenol, and by NO3‐. Kinetics of inhibition of NO2‐ assimilation by NO3‐ appeared to be “competitive.” D. brightwellii cells grown on NO2‐ took up NO3‐ in both light and dark and in both cases the uptake was inhibited by p‐chloromercuribenzoate, but not by DCMU, KCN, or by NO2‐. Most of the NO3‐ taken up in the dark was recovered unchanged from the cells. However only 40% of NO3‐ taken up in light was recovered from the cells and no NO2‐ was found. This suggests that a photosynthetic nitrate reduction mechanism was active in these cells. DCMU inhibited the light‐induced NO3‐ reduction. This mechanism of NO3‐ reduction is distinct from that involving NADH nitrate reductase in D. brightwellii since the concentration of the latter enzyme is very low in cells grown on NO2‐. Saturation kinetics were observed for NO2‐ and NO3‐ uptake. Half‐saturation concentrations (Ksvalues) were 4 and 2 μM, respectively. These values are compared with those obtained for NO2‐ and NO3‐ assimilation by other unicellular algae. The comparisons show lower Ksvalues in oceanic species compared with tide‐pool or freshwater algae and they support the idea that Ksvalues for NO3‐ assimilation may provide a key to understanding species succession when this is due to declining: nitrate concentrations in the sea.
SPORANGIA OF RALFSIA FUNGIFORMIS (GUNN.) SETCHELL ET GARDNER12
Authors: Edelstein T. , Chen L. , McLachlan J. 
Published: April 2007

SUMMARY Unilocular and plurilocular sporangia of Ralfsia fungiformis are, for the first time, recorded for North America. The validity of certain types of structures, considered by some authors as plurilocular sporangia, is discussed.
SILICON METABOLISM IN DIATOMS. VI. SILICIC ACID UPTAKE BY A COLORLESS MARINE DIATOM, NITZSCHIA ALBA LEWIN AND LEWIN12
Authors: Lewin Joyce , Chen Ching‐hong 
Published: April 2007

SUMMARY Cells of the colorless, heterotrophic diatom Nitzschia alba, after removal from the culture medium, were able to absorb silicic acid from a salt solution lacking carbon, nitrogen, and phosphorus. Silicic acid uptake continued for approximately 12 hr. At low cell densities (ca. 2.5×105 cells/ml), the cell number doubled under these conditions. At high cell densities (ca. 2 ×106 cells/ml) no cell division resulted. When such cells were washed with a salt solution, their ability to absorb silicic acid was somewhat impaired. The degree of impairment became progressively more pronounced after subsequent washing treatments. A heat‐stable factor washed from the cells and present in the first “wash water” was able to restore completely the ability of washed cells to absorb silicic acid. The factor was not identified. Aspartic acid (5 ± 10‐4 M) or glutamine (5 ±10‐4 M) when added to the saline solution similarly promoted complete recovery. A t such concentrations, these substances had only a slight effect on unwashed cells. A solution of 5 ±10‐4 M Na glutamate (or aspartic acid plus glutamine) had an men more pronounced effect, and in addition promoted cell division or growth" of unwashed cells. Several other amino acids and other compounds tested were apparently without effect.
CULTURE STUDIES ON THE MARINE GREEN ALGA HALICYSTIS PARVULA‐DERBESIA TENUISSIMA. III. CONTROL OF GAMETE FORMATION BY AN ENDOGENOUS RHYTHM12
Authors: Page Joanna Ziegler , Sweeney Beatrice M. 
Published: April 2007

SUMMARY Evidence is presented for an endogenous rhythm which controls gamete formation in the coenocytic gametophytic stage of the marine alga Derbesia tenuissima (De Notaris) Crouan fr. (Chlorophyceae), formerly known as Halicystis parvula. The rhythm is present under conditions of constant light and temperature, or in alternating light and darkness (LD 12 :12 or LD 8 : 8). Under controlled conditions in the laboratory, the basic period of this rhythm is 4‐5 days. The period is affected very little by temperature or light intensity. Gametangia may appear only at every other cycle of the underlying rhythm at approximately 8‐day intervals, or even every third cycle at intervals of about 12 days. The observation that the interval between the appearance of new gametangia does not vary continuously when light or temperature is varied but tends to be a multiple of 4 days is the strongest evidence available that a true endogenous rhythm with a period of about 4 days is present in Derbesia. Evidence is presented that circadian rhythmicity does not play a part in the timing of the initiation of gametangia in this organism.
STUDIES AT OYSTER BAY IN JAMAICA, WEST INDIES. IV. OBSERVATIONS ON THE MORPHOLOGY AND ASEXUAL CYCLE OFPYRODINIUM BAHAMENSEPLATE12
Authors: Buchanan R. J. 
Published: April 2007

SUMMARYThe morphology and asexual cycle of the luminescent armoured dinoflagellate, Pyrodinium bahamensePlate, were examinedin situandin vitro.Several previously unreported aspects of the cycle are described. Attempts to induce the formation of these alternate life stages by imposing new conditions were unsuccessful.
ULTRASTRUCTURE OF SPONGIOCHLORIS TYPICA DURING SENESCENCE12
Authors: McLean Robert J. 
Published: April 2007

SUMMARY The ultrastructural changes which occurred during senescence in the stationary phase of growth of the unicellular green alga Spongiochloris typica were observed. The cell wall consists of a membrane like primary wall and an inner secondary wall which becomes progressively thickened with age of the culture. During senescence the lamellae become more compact within the chloroplast. The major feature of aging is the appearance of lipid bodies which eventually come to occupy a major portion of the cell lumen. The ultrastructural changes observed to occur during senescence are discussed in relation to physiological data.
REPRODUCTION IN ZONARIA FARLOWII. I. GAMETOGENESIS, SPOROGENESIS, AND EMBRYOLOGY1
Authors: Liddle Larry Brook 
Published: April 2007

SUMMARY The brown alga Zonaria farlowii which exhibits an alternation of isomorphic generations has been found to be a particularly suitable organism for a comparative study of game to gene sis, sporogenesis, and embryonic development. The germinations of the zygote and spore have been compared and found to be similar. The development of the oogonium and sporangium has been studied with the light and electron microscopes, in an attempt to discern ontogcnetical similarities or differences. The timing and periodicity of oogenesis and sporogenesis were found to differ: oogonial development requires a lunar month from the time of its initiation to the time of egg release which occurs around the first quarter of the moon, whereas the sporangium does not follow this periodicity. The development of the spore embryos and zygotic embryos is essentially the same. It appears that the difference between the 2 phases of the life cycle exists only in the later stages of oogenesis and sporogenesis. These differences continue in the egg until fertilization, after which the zygote has the same cytoplasmic configuration as the spore. It is also notable that during release of the spore it must increase in size considerably since before germination begins it has attained the size of the egg.
INVESTIGATION OF A DIATOM POPULATION FROM MINE TAILINGS IN NYE COUNTY, NEVADA, U. S. A.1
Authors: VanLandingham S. L. 
Published: April 2007

SUMMARY A diatom population consisting of 31 taxonomic entries was found in tailings from an abandoned mine near Ichthyosaur Paleontologic State Monument, Nye County, Nevada, U.S.A. The diatom population of the mine tailings resembled those found in dry lakes of the vicinity which are similar to some soil diatom populations. The mine tailings population was very similar to some Quaternary diatom assemblages in the vicinity and in other parts of the conterminous United States. The diatom population indicated that alkaline and oligohalobous conditions were prevalent with associated “indifference” with respect to the current spectrum.
CONTROL OF COLONY AND UNICELL FORMATION IN A SYNCHRONIZED SCENEDESMUS12
Authors: Trainor Francis R. , Rowland Helen L. 
Published: April 2007

SUMMARY Colony formation in a synchronized Scenedesmus could be controlled by the addition of 0.05% Na3 citrate or 85 μM EDTA to modified Bristol's medium. No unicells were formed; only S. quadricauda‐like or S. longispina‐type colonies were observed in young cultures grown in that medium. A colony population could be made completely unicellular in 2 days if grown in soil‐Bristol's medium and transferred daily. The pleomorphic Scenedesmus was examined in synchronized culture. When the organism was grown in a defined medium in a 15‐hr light /9‐hr dark cycle on a roller tube rotator at 2‐6 rpm and transferred daily, synchrony of cell division and release of the products were achieved. In a synchronized culture 2 doublings/day were recorded, with most cytoplasmic cleavages and all releasing of daughter cells taking place in the dark period. In many observations with several synchronized strains of Scenedesmus, no fixed pattern of release of daughter products from mother cells or colonies was detected. Colonies or unicells had their full spine complement at the time of release. As a cell or colony aged the spines sometimes increased in thickness. Other Scenedesmus strains were examined to provide supporting data.
REPRODUCTION OF THE ARTICULATED CORALLINE AMPHIROA EPHEDRAEA1
Authors: Johansen H. William 
Published: April 2007

SUMMARY Developmental events in the formation of reproductive structures in tetrasporangial, male, and female plants of Amphiroa ephedraea from South Africa were studied. An early step in the formation of a conceptacle is the elongation of a stratum of cortical cells, the cavity cells, to form a dome surmounted by an a cellular cap. Atrophy of the cavity cells to form a conceptacular cavity accompanies the subsequent development of reproductive structures. Tetrasporangial conceptacles differ from sexual conceptacles in that the reproductive cells develop in a peripheral ring and in the fact that the tissue lateral to these cells does not overgrow the fertile area. Finally, a comparison of some of the features of reproduction in A. ephedraea is made zuith. comparable features in other corallines.
SOME OBSERVATIONS ON THE VERTICAL MIGRATION OFDINOFLAGELLATES 12
Authors: Eppley R. W. , Holm‐Harisen O. , Strickland J. D. H. 
Published: April 2007

SUMMARY The technique of measuring chlorophyll concentration in vivo by fluorometric analysis has been adapted to studying the diurnal migration of dino‐flagellates in the sea and also in a deep tank (3 m in diameter by 10 m deep). The downward migration of Ceratium furca was followed during a bloom off the California coast. The main band of cells migrated from the upper 2 m to a depth of 5 m about 2 hr after sunset, and was dispersed between 5 and 16 m 4.5 hr after sunset. Cultures of Gonyaulax polyedra and Cachonina niei both migrated to the surface of the deep lank during illumination and migrated downward during darkness at a rate of 1‐2 mjhr. The downward migration was observed to begin before the light was turned off, indicating that migration is correlated with a cellular periodicity which is to some extent independent of the light regime. Further evidence for such a periodicity was afforded by observations that C. niei start to migrate up in the water column before start of the light period. Nitrogen‐limited cells of G. polyedra showed no diurnal migration, but within 1 day after addition of a nitrogen source they recovered their full migratory ability. Cells of C. niei, however, continued to migrate during 5 days of N‐starvation, although they did not concentrate in the upper 1/2 m as did the control cells.
SULFONAMIDE INHIBITION IN MONOCHRYSIS LUTHERP1
Authors: Ukeles Ravenna 
Published: April 2007

SUMMARY The effect of sulfonamides on growth of the chry‐somonad, Monochrysis lutheri, in a synthetic sea‐water medium was examined over a period of 14 days. The population increased at all sulfonamide concentrations during the first several days of incubation before inhibition became apparent. Inhibitory concentrations ranged from 0.01 to 1.0 mg%. Inhibition luas most pronounced in sulfathiazole; sulfamethazine, sulfapyridine, and sulfanilamide followed in decreasing order. p‐Arninobenzoic acid (0.001‐1.0 mg%) competitively reversed inhibition. Folic acid, thymine, adenine, and vitamin B12 neither reversed the inhibition nor spared the requirement for p‐aminobenzoic acid. The significance of the inhibition pattern and the potential use of antimetabolites in the marine environment were discussed.
STRUCTURE AND REPRODUCTION OF NEOARDISSONEA KYLIN (RHODOPHYTA‐NACCARIACEAE)1
Authors: Womersley H. B. S. , Abbott Isabella A. 
Published: April 2007

SUMMARYNeoardissonea naccarioides (J. Ag.) Kylin, the type and only species of its genus, is shown to be referable to Naccaria Endlicher, to which genus it is transferred as Naccaria naccarioides (J. Ag.) comb. nov.
TAXONOMIC CONFUSION CONCERNING CERTAIN FILAMENTOUS BLUE‐GREEN ALGAE1
Authors: Brock Thomas D. 
Published: April 2007

SUMMARY 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.
CHLOROPLAST DEVELOPMENT AND ULTRESTRUCTURE IN THE FRESHWATER RED ALGA BATRACHOSPERMUM1
Authors: Brown D. L. , Weier T. E. 
Published: April 2007

SUMMARY Chloroplast development and ultrastructure of the freshwater red alga Batrachospermum moniliforme are described. Chloroplasts develop from proplastids which have a double‐membraned chloroplast envelope and a parallel double‐membraned outer photo‐synthetic lamella. Of these 2 double‐membraned structures of the proplastid, only the outermost pho‐tosynthetic lamella functions in production of further lamellae. The mature chloroplast consists of 2 or more concentric lamellae and a variable number of nonconcentric lamellae. These lamellae are not dense, uninterrupted sheets as described for other red algae, but are largely constructed of tubules, lying side by side, that form interrupted lamellar sheets. The possible physiological significance of lamellar interruptions in providing path‐ways for movement of materials in the chloroplast stroma is discussed.
XYLULOSE, AN ALGAL GROWTH INHIBITOR12
Authors: Wu Madeline , Alston Ralph E. , Mabry Tom J. 
Published: April 2007

SUMMARY The growth of Chlorococcum echinozygotum was previously known to be inhibited by an autoclaved solution of xylose in Bold's modified Bristol's medium. We now report the isolation of 2 inhibitory compounds derived from xylose during autoclaving, and the identification of one of them as xylulose. Two strains of C. echinozygotum were isolated, one of which had physiologically adapted to xylulose. The growth rates of both strains were studied using varying amounts of xylulose. Cell counting studies indicated that the zoospores of the unadapted strain were most severely affected by xylulose inhibition and that the zygospores were most resistant.
OBSERVATIONS ON THE FINE STRUCTURE OF OEDOGONIUM. V. EVIDENCE FOR THE DE NOVO FORMATION OF PYRENOIDS IN ZOOSPORES OF OE. CARDIACUM123
Authors: Hoffman Larry R. 
Published: April 2007

SUMMARY Ultrastructural studies of the chloroplasts of zoospores and developing zoospores of Oedogonium carcliacum have disclosed the occurrence of numerous incipient pyrenoids. A single developing zoospore may possess several score of these structures which appear to arise de novo in the chloroplast stroma and seem to lack any direct association with mature pyrenoids which are also present in the cells. The incipient pyrenoids lack the associated starch grains and the membrane‐limited channels characteristic of mature pyrenoids, but they are readily recognized in the chloroplasts since they demonstrate a greater granularity and electron density than the surrounding chloroplast stroma. The granularity and electron density of the incipient pyrenoids match the ultra‐structural appearance of the matrix of mature pyrenoids. The smallest of the incipient pyrenoids examined from serial sections had a maximum diameter of less than 0.3 μ. This may be compared with the size of mature pyrenoids, many with a maximum diameter of over 5.0 μ. In all the zoospores and developing zoospores examined, only one mature pyrenoid was observed in an apparent stage of division.
DEOXYRIBONUCLEIC ACID CONTENT OF THE THREE CELL TYPES OF PHAEODACTYLUM TRICORNUTUM BOHLIN1
Authors: Darley W. Marshall 
Published: April 2007

SUMMARY There is no significant difference in the DNA content of the oval, fusiform, and triradiate cell types of Phaeodactylum tricornutum, suggesting that they do not represent an alternation of haploid and diploid generations. The triradiate cells have a shorter generation time than the oval or fusiform cells.