bluuebunny/crossref_metadata_2025_split huggingface dataset:
STUDIES ON DEVELOPING AND RELEASED SPERMATIA IN THE RED ALGA, TIFFANIELLA SNYDERAE (RHODOPHYTA)1
Authors: Fetter Richard , Neushul Michael 
Published: August 2010

ABSTRACTDeveloping and released spermatia of the red alga, Tiffaniella snyderae (Farl.) Abb. were studied. Spermatia were observed under hydrodynamically defined conditions and found to be released from the exposed spermatangial heads in a spermatium‐plus‐strand unit that remained connected to the spermatangial head. Interactions of single‐spermatial strands resulted in the formation of multi‐spermatial strands as long as 600 μm with as many as 47 spermatia along their length; however, most were 100–200 μm with 8–21 spermatia. Strand length and number of spermatia were correlated. Spermatial strands contracted or extended and rotated as the water velocity past the plant was changed, and in still water the strands retracted into a clump on the spermatangial head surface. Each strand type exhibited a characteristic threshold water velocity at which it reached maximum length, and above which it broke and was carried away. Fluorescence microscopy showed that the strands did not contain nucleic acid (DNA) and could thus be differentiated from filamentous blue‐green algal and bacterial epiphytes. Histochemical staining indicated that the strands and spermatial vesicles contained an acidic, sulfated polysaccharide. Chelation of Ca2+ with EGTA resulted in strand breakdown suggesting that this divalent cation may be involved in strand integrity.Scanning electron microscopy revealed that release from the spermatangia occurred through tears in the cuticle covering the spermatangial head if it was still present, or from exposed spermatangia. Individual spermatia were attached tangentially to a well‐defined strand 0.64 μm in diameter in the contracted state to 0.2 μm in the extended state. Transmission electron microscopy of spermatangial heads showed that immature spermatangia were characterized by a centrally positioned nucleus and abundant ER cisternae filled with a moderately electron dense granular material. Later in development the spermatangia acquire two spermatial vesicles containing highly convoluted fibrillar contents. The cell becomes polarized with the nucleus displaced apically and the spermatial vesicles occupying the basal half of the spermatangium. At maturity one of the vesicles is released basally. Liberated spermatia contain a membrane‐bound nucleus and mitochondria and are associated with an oblong accumulation of fibrous material similar in size and position to the strand observed with the SEM. These strands are discussed in relation to red algal fertilization and other phases of the red algal life‐history.
MARIPELTA ATLANTICA SP. NOV. (RHODOPHYTA, RHODYMENIALES) A NEW DEEP‐WATER ALGA FROM FLORIDA1
Authors: Eiseman Nathaniel J. , Moe Richard L. 
Published: August 2010

ABSTRACTA red alga with a cylindrical stipe bearing a single deciduous blade was collected in deep water off the east coast of Florida. It is described as Maripelta atlantica sp. nov., differing from M. rotata (Dawson) Dawson (the type of the genus, from deep water off California and Baja California) chiefly by having an annular tetrasporangial nemathecium on the lower surface of the blade rather than scattered nemathecia on the upper surface. Both species are vegetatively and reproductively distinct from M. thivyae Dawson, which is transferred to Halichrysis. New information is given regarding the reproduction and distribution of M. rotata.
COMPARATIVE KINETIC STUDIES OF NITRATE‐LIMITED GROWTH AND NITRATE UPTAKE IN PHYTOPLANKTON IN CONTINUOUS CULTURE1
Authors: Gotham Ivan J. , Rhee G‐Yull 
Published: August 2010

ABSTRACTA comparative study of nitrate‐limited growth and nitrate uptake was carried out in chemostat cultures of Ankistrodesmus falcatus (Corda) Ralfs., Asterionella formosa Hass., and Fragilaria crotonensis Kit. In each species growth rate (μ) was related to total cell nitrogen or cell quota (q) by the empirical Droop growth function.Nitrate uptake was a function of both external N concentration and q. The apparent maximum uptake rate (Vm') at a given μ was inversely related to q – q0, where q0 is the minimum quota. The apparent half‐saturation constant for uptake, (Km') appears to show a slight inverse trend with μ, although statistical analysis shows that this trend is inconclusive. When q approaches q0, Vm' is several orders of magnitude greater than μq, the calculated steady‐state uptake rate. As q increases, however, the difference between these two variables decreases sharply until q approaches qm, the cell quota for nitrogen‐rich cells. At this point the difference between μq and Vm' disappears. This behavior is explained by the feedback regulation of N uptake. The inverse relationship between Vm' and q – q0 can be described by an empirical three‐parameter equation.
TEMPERATURE DEPENDENCE OF GROWTH AND PHOSPHORUS UPTAKE IN TWO SPECIES OF VOLVOX (VOLVOCALES, CHLOROPHYTA)1
Authors: Senft W. Herbert , Hunchberger Robert A. , Roberts Kenneth E. 
Published: August 2010

ABSTRACTThe growth of Volvox globator L. and Volvox aureus Ehr. was measured at five temperatures and nine phosphorus concentrations. Growth rates were hyperbolically related to phosphorus concentrations for all temperatures using a Monod growth model. Optimal growth rates of 1.17 and 1.00 doublings d−1 were obtained at 20°C for V. globator and V. aureus, respectively. Neither species grew at 5°C. The half‐saturation constants for growth, Ks, were lower for V. aureus. Phosphorus uptake by both species was also dependent upon external phosphorus concentrations and temperature. At all temperatures, maximum phosphorus uptake (μmol P colony−1 min−1) was similar for both species; however, the half‐saturation constants for uptake showed significant differences between the species. Comparisons of the kinetic constants for growth and phosphorus uptake suggest that V. aureus will outcompete V. globator under phosphorus limited, conditions.
COMPARATIVE CYTOLOGY AND TAXONOMY OF THE ULVAPHYCEAE. III. THE FLAGELLAR APPARATUSES OF THE ANISOGAMETES OF DERBESIA TENUISSIMA (CHLOROPHYTA)1
Authors: Roberts Keith R. , Sluiman Hans J. , Stewart Kenneth D. , Mattox Karl R. 
Published: August 2010

ABSTRACTThe components of the flagellar apparatuses of the male and female gametes of Derbesia tenuissima (De Not.) Crouan are compared with those in other swarmers of green algae. Both the male and female gametes were found to have a cruciate microtubular root system, a non‐striated capping plate which connects basal bodies, two electron dense terminal caps which partially cover the proximal end of the basal bodies, and two small system II fibrous roots. Similarities exist between these components and those suggested to be typical of ulvalean swarmers. Based upon these similarities, it is proposed that the Caulerpales be classified in the Ulvaphyceae rather than in the Charophyceae or Chlorophyceae.
AN ALTERNATE GROWTH PATTERN FOR LAMINARIA LONGICRURIS1,2
Authors: Anderson M. Robin , Cardinal André , Larochelle Jacques 
Published: August 2010

ABSTRACTA population of Laminaria longicruris de la Pylaie was followed for a year at Bic Island, Quebec, Canada where nutrient levels in the seawater were elevated throughout the year. Tagged kelp were measured each month for growth and analyzed for alginic acid, laminaran, mannitol, carbon, nitrogen, and nitrate. Maximum growth (3.5 cm · d−1) was observed in June, and minimal growth (0.18 cm · d−1) from December to February, when ice cover limited light levels. No reserves of carbon or nitrate were formed. Laminaran levels remained below 2.7% dry weight while tissue nitrate did not exceed 0.75 μmol · g−1 dry weight. Total carbon produced per plant was 40 g C · yr−1. Nutrient availability enables the kelp to take advantage of summer light and temperature conditions to grow rapidly.
EFFECTS OF Si:P CONCENTRATION RATIOS AND NUTRIENT LIMITATION ON THE CELLULAR COMPOSITION AND MORPHOLOGY OF ASTERIONELLA FORMOSA (BACILLARIOPHYCEAE)1
Authors: Holm Nancy Peterson , Armstrong David E. 
Published: August 2010

ABSTRACTThe freshwater diatom Asterionella formosa Haas. was grown in semicontinuous culture at 20°C under continuous cool‐white fluorescent light of ca. 20 μEin · m−2· s ·−1 in a medium containing Si: P in various concentration ratios. The cell quotas of P and Si changed in relation to the available concentrations of P and Si at constant μ= 0.11 and 0.16 d−1. Under Si‐limitation, the P cell quota increased by over an order of magnitude as the influent [Si:P] decreased. The Si cell quota increased with increase in [Si] in the influent medium, and it increased as [P] increased at a specific [Si]. Under P‐limitation, the P cell quotas were fairly constant and low; the Si cell quotas were relatively high and decreased slightly as influent [P] and [Si] increased. Asterionella stored up to 28 times more P and 2 times more Si than needed. The number of Asterionella cells per colony varied as a function of the influent [Si:P] and nutrient limitation being usually less than or equal to 6 when P‐limited, and greater than 10 when Si‐limited.
ULTRASTRUCTURAL VARIATIONS IN CRYPTOMONAD FLAGELLA1
Authors: Kugrens Paul , Lee Robert E. , Andersen Robert A. 
Published: August 2010

ABSTRACTThe arrangement of flagellar appendages in 19 cryptomonad species was examined and four new flagellar types are described. The first new type has a single row of mastigonemes on both flagella and hairs on the side opposite the mastigonemes. The second type, which is common, has unilateral rows of mastigonemes on both flagella, but no hairs. A third type has an acronematic short flagellum and a single row of mastigonemes on the long flagellum. A fourth type lacks mastigonemes but has a unilateral row of curved “spikes” on the short flagellum and hairs on both flagella. These additional flagellar variations may contribute to a more natural system of classification for cryptomonads.
INTRASPECIFIC VARIATION IN THE DINOFLAGELLATE PERIDINIUM VOLZIP1
Authors: Hayhome Barbara A. , Whitten D. Jean , Harkins Kristi R. , Pfiester Lois A. 
Published: August 2010

ABSTRACTClonal isolates of Peridinium volzii Lemmerman were analyzed morphologically and biochemically. Morphological observations at the light microscope level show the clones to be different varieties and forms of the same species. Biochemical analysis by enzyme electrophoresis and flow cytometric determination of nuclear DNA quantities indicates that these isolates are genetically heterogeneous without any clear correlation existing between morphological variation and biochemical variation. Isozyme analysis, however, indicates that strains from the same location are generally more related to each other than they are to isolates with other geographical origins. In general, our results suggest the presence of genetic redundancy and a multiclonal origin for individuals of the same species present in the same locale.
HETEROCOCCUS ENDOLITHICUS SP. NOV. (XANTHOPHYCEAE) AND OTHER TERRESTRIAL HETEROCOCCUS SPECIES FROM ANTARCTICA: MORPHOLOGICAL CHANGES DURING LIFE HISTORY AND RESPONSE TO TEMPERATURE1
Authors: Darling Richard B. , Friedmann E. Imre , Broady Paul A. 
Published: August 2010

ABSTRACTStrains of Heterococcus endolithicus sp. nov., H. pleurococcoides Pitschmann, H. caespitosus Vischer, and H. protonematoides Vischer isolated from terrestrial habitats in Antarctica were studied in culture. Morphology of the algae changes with stage in life history. The characteristic branching patterns are not present in very young or old cultures. Filament formation is suppressed when cultures are grown outside their optimal temperature range.
STUDIES OF MESOHERBIVORY IN AQUARIA AND IN AN UNBARRICADED MARICULTURE FARM ON THE CHINESE COAST1
Authors: Brawley Susan H. , Xiugeng (X. G. Fei) Fei 
Published: August 2010

ABSTRACTThe effects upon macrophytic and epiphytic algae of caprellid amphipods, including Caprella irregularis Mayer, and of gammarid amphipods, including Ampithoe lacertosa Bate, Jassa falcata (Montagu) and Pontogeneia rostrata Gurjanova, were studied in aquaria and in a coastal mariculture farm near Qingdao, People's Republic of China. The macrophytic species studied included Enteromorpha linza (L.) J. Agardh, Gracilaria asiatica Zhang & Xia, Gracilaria lemaneiformis (Bory) Weber‐van Bosse and Scytosiphon lomentaria (Lyngbye) C. Agardh. These algae and amphipods were selected for study because of their local abundances. Aquarium experiments demonstrated that C. irregularis, J. falcata and P. rostrata feed on ephemeral/epiphytic algae. A. lacertosa (adults and juveniles) ate Gracilaria but preferred E. linza. The different species of amphipods had substantially different patterns of daily activity.Caprellids prevented epiphytic overgrowth of G. asiatica when added to plants in an experimental, openocean, mariculture farm, despite the presence of numerous amphipod predators (e.g. the fishes Hexagrammos otakii Jordan & Starks and Sebastes thompsoni Jordan & Hubbs). Periodic removals of all (naturally colonizing) amphipods from another group of plants in the farm resulted in heavy epiphytic overgrowth. Since these results were obtained in an unbarricaded mariculture farm, we conclude that mesoherbivores may have large effects upon algal community structure in temperate intertidal and subtidal habitats.
GRAZING OF FRESHWATER RHODOPHYTA1
Authors: Hambrook Julie A. , Sheath Robert G. 
Published: August 2010

ASTRACTGrazing of freshwater Rhodophyta was examined from three perspective: observation of algal fragments in gut contents of herbivores collecte from streams with populations of red algae, measurement of ignestion rates of three inveratebrates in single diet and choice experiments and analysis of potential food value of the rhodophytes by determining protein, carobohydrate, lipid and estimated caloric contents. The algal thallus forms studied were Audouinella violacea (Kütz.) Hamel, which consists of simple filaments growing in dense tufts, Batrachospermum virgatum (Kütz.) Sirod., which is a densely branched mucilaginous filament, and Tuomeya americanna (Harv.) Papenfuss, which is a branched cartilaginous psedoparenchyma. The thirteen invertebrate taxa containing pieces of one or more of these algae in theri guts included two amphipods, two mayfly larvae, three caddisfly larvae, one beetle larva, four chironomids and one snail. The frequencies with which the Rhodophyta were found in the gut contents were as follows: Audouinella 31%, Tuomeya 38%, Batrachospermum 46% and “chantransia stages” 54%. In all of the individual and choice experiments, Audouinella was ingested at the greates rate, followed by Batrachospermum and then Tuomeya, regardless, of the grazer. Audouinella had the highest protein and lipid contents while Tuomeya displayed the opposite trent. All three rhodophytes had very large calofic values (5.0–6.8 kcal μg−1dry weight) due to their high lipid and low ash contents. Therefore, preferential grazing of Audouinella appears to be bases on its simple thallus and high protein contents rather than its calorific value.
DISTRIBUTION OF THE GENUS CYCLOTELLA IN RELATION TO pH IN PRECAMBRIAN SHIELD LAKES: IMPLICATIONS FOR DIATOM‐INFERRED pH1
Authors: Taylor M. C. , Duthie H. C. , Smith S. M. 
Published: August 2010

ABSTRACTRecent research on relationships between diatoms and pH suggests that the genus Cyclotella exhibits a strong relationship with lake acidity, being almost totally absent below pH 5.5. This decline has been used as an indicator of lake acidification in paleolimnological studies. In this study C. stelligera V.H. and C. kützingiana Thwaites were abundant in Precambrian Shield lakes with pH as low as 4.5. Cyclotella comta (Ehr.) Kütz. was found in lakes of pH < 5.5, but maximum abundance was observed in lakes of pH > 5.5. Cyclotella michiganiana Skv. was found in lakes of pH < 6.0. These results indicate that the use of C. stelligera, C. kützingiana, and possibly C. comta, in paleolimnological investigations of lake acidification, should be approached with caution. These taxa may exhibit a decline in abundance with decreasing lakewater pH, but this is partially a morphometric effect not necessarily related to anthropogenic acidification.
ENTOSIPHON SULCATUM (EUGLENOPHYCEAE): FLAGELLAR ROOTS OF THE BASAL BODY COMPLEX AND RESERVOIR REGION1,2
Authors: Solomon Jean A. , Walne Patricia L. , Kivic Peter A. 
Published: August 2010

ABSTRACTThe flagellar root system of Entosiphon sulcatum (Dujardin) Stein (Euglenophyceae) is described and compared with kinetoplastid and other euglenoid systems. An asymmetric pattern of three microtubular roots, one between the two flagellar basal bodies and one on either side (here called the intermediate, dorsal, and ventral roots), is consistent within the euglenoid flagellates studied thus far. The dorsal root is associated with the basal body of the anterior flagellum (F1) and lies on the left dorsal side of the basal body complex. Originating between the two flagellar basal bodies, and associated with the basal body of the trailing flagellum (F2), the intermediate root is morphologically distinguished by fibrils interconnecting the individual microtubules to one another and to the over lying reservoir membrane. The intermediate root is often borne on a ridge projecting into the reservoir. The ventral root originates near the F2 basal body and lies on the right ventral side of the cell. Fibrillar connections link the membrane of F2 with the reservoir membrane at the reservoircanal transition level. A large cross‐banded fiber joins the two flagellar basal bodies, and a series of smaller striated fibers links the anterior accessory and flagellar basal bodies. Large nonstriated fibers extend from the basal body complex posteriorly into the cytoplasm.
COCCOLITH‐ASSOCIATED POLYSACCHARIDES FROM CELLS OF EMILIANIA HUXLEYI (HAPTOPHYCEAE)1
Authors: Borman Anton H. , de Jong Elisabeth W. , Thierry Remi , Westbroek Peter , Bosch Leendert , Gruter Marijke , Kamerling Johannes P. 
Published: August 2010

ABSTRACTCoccoliths of Emiliania huxleyi (Lohmann) Hay and Mohler, a unicellular calcifying alga, consist of calcite closely associated with an acidic, Ca2+‐binding polysaccharide. This polysaccharide is thought to play a regulatory role in coccolith synthesis by interfering with CaCO3 crystallization. Here we show that the polysaccharides from three different strains, A 92, L and 92 D, all inhibit the precipitation of CaCO3 in vitro to the same extent. The monosaccharide compositions of the A 92 and L polysaccharide are similar. The 92 D material, however, deviates from the other two: it contains significantly lower amounts of methylated sugars and ribose, and elevated levels of rhamnose and galactose. It also contains antigenic determinants not detected in the A 92 and L polysaccharides. In contrast to the latter two macromolecules the 92 D polysaccharide migrates as two bands upon polyacrylamide gel electrophoresis, possibly resulting from complexing with small amounts of protein. The coccolith polysaccharide from L cells, cultured at an elevated growth rate, also migrates as two bands. This phenomenon is due to an increase in molecular size distribution. The results suggest that certain properties of the molecule may be subject to variation without interfering with its function.
MASSIVE ACCUMULATION OF PHYTOENE INDUCED BY NORFLURAZON IN DUNALIELLA BARDAWIL (CHLOROPHYCEAE) PREVENTS RECOVERY FROM PHOTOINHIBITION1
Authors: Ben‐Amotz Ami , Gressel Jonathan , Avron Mordhay 
Published: August 2010

ABSTRACTThe effects of nanomolar to micromolar concentrations of the herbicide norflurazon were studied in Dunaliella bardawil Ben‐Amotz et Avron, a β‐carotene‐accumulating halotolerant alga. The large amount of β‐carotene which Dunaliella bardawil can contain, around 8% of the algal dry weight, is reduced to 0.2% by treatment with 100 nm norflurazon. Simultaneously, phytoene is accumulated to a similar level of about 8%. The gradual increase in phqtoene content, in response to increasing norflurazon concentrations, corresponds to the decrease in β‐carotene, with no evident change in other isoprenoid intermediates. Carotene‐rich Dunaliella bardawil is substantially resistant to high‐intensity photoinhibition. This resistance is lost in cells grown to contain low & carotene and in the nor‐urazon‐treated phytoene‐rich cells. These obseruations are in agreement with the hypothesis that the accumulated β‐carotene in Dunaliella bardawil portects the cells against injury by excessive irradiation.
INCOMPLETENESS OF THE COCCOSPHERE AS A POSSIBLE STIMULUS FOR COCCOLITH FORMATION INPLEUROCHRYSIS CARTERAE(PRYMNESIOPHYCEAE)1
Authors: van der Wal Paul , de Vrind Johannes P. M. , de Vrind‐de Jong Elisabeth W. , Borman Anton H. 
Published: August 2010

ABSTRACTPleurochrysis carterae is a marine biflagellate that produces calcified structures called coccoliths. The coccoliths are formed inside the cells and released from the latter after formation. The light dependence of calcium incorporation in this species was studied using45Ca as a tracer. Cells exposed to a repeating cycle of 16 h of light and 8 h of darkness incorporated calcium in extracellular coccoliths at a more or less constant rate throughout a cycle. The cells divided during the dark periods with a concomitant decrease in size. Their size increased during the light periods. Coccolith formation in cells incubated in continuous darkness was greatly reduced and finally ceased. These cells did not divide and did not increase in size. Removal of extracellular coccoliths prior to the calcium incorporation experiments stimulated coccolith formation both in dark‐incubated cells and in cells exposed to a repeating light‐dark cycle. Cells in the stationary phase of growth ceased producing coccoliths. Calcification could be induced in these cells by removal of the extracellular coccoliths. Based on these findings we suggest that cells of Pleurochrysis carterae tend to produce a complete cover of coccoliths and that the available cell surface is a factor controlling coccolith formation.
EFFECT OF LIGHT CYCLE ON DIATOM FATTY ACID COMPOSITION AND QUANTITATIVE MORPHOLOGY1
Authors: Sicko‐Good Linda , Simmons Mila S. , Lazinsky Diane , Hall Janet 
Published: August 2010

ABSTRACTQuantitative cytological and fatty acid composition was determined for the diatom Cyclotella meneghiniana Kütz, Data from four separate experiments were examined to elucidate changes that may occur with respect to daily photoperiod. Overall, fatty acid composition is similar to that reported for other diatoms with the exception that the C16 fatty acids constitute approximately 70% of all fatty acids. The major fatty acids are C14:0, 16:1, 16:0, 18:0, and 20:5. Fatty acids that are present in minor amounts are iso‐14:0, iso‐15:0, 15:0, 17:0, 18:4, 18:2, 18:1, 19:0, 20:0, 22:0, and 23:0.Cytological composition is similar to that previously reported with the chloroplast and vacuole being the largest compartments within the cell. Changes in both cytological and fatty acid composition were studied with respect to the light / dark cycle. Chloroplast and lipid relative volume are greatest during the early part of the dark period. Nuclear relative volume is lowest in the dark and increases throughout the light period.Total unsaturated fatty acids, including the C20:5 fatty acid, are lowest in the early part of the light period and highest in the dark. The sum of the C16 fatty acids remains constant at 70% of total fatty acids in the cells throughout the light/dark cycle, although percent composition of these two fatty acids shifts.The data suggest that cyclical changes occur in both quantitative morphology and fatty acids composition with respect to daily photoperiod. The cells, although not rigidly synchronized, most likely divide in the latter part of the dark period or in the first hours of the light period. Lipids increase dramatically in the dark. The ecological implications of lipid storage are discussed in relation to lipophilic toxicants.