bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding Change in Political Science: On the Need to Bring Space into Theoretical Positions and Empirical Analyses
Authors: Bates Stephen R. , Smith Nicola J.
Published: March 2008

In recent times, issues surrounding change have become increasingly important in the study of political analysis. This is especially true within strains of new institutionalism such as historical institutionalism and the ‘Varieties of Capitalism’ approach. However, although this has led to a sensitising towards the temporal dimension, the spatial dimension has been relatively ignored. This is arguably problematic, as a fuller understanding of space and the spatiality of social and political relations would lead to more coherent and accurate analyses of political phenomena that currently characterise historical institutionalism. Indeed at an ontological level, drawing on work within the natural sciences and geography, it is impossible to talk of time without reference to spatiality and of space without reference to temporality. This short article reviews some of the more prominent historical institutionalist literature that deals with change and renders explicit the problematic conceptualisation of space, and consequently time, which underpins their analyses. Drawing on Massey and Sayer, it proceeds to outline briefly a relational conception of space and the difference that space makes to political analyses.
TRANSLOCATION IN MACROCYSTIS. III. COMPOSITION OF SIEVE TUBE EXUDATE AND IDENTIFICATION OF THE MAJOR C14‐LABELED PRODUCTS1
Authors: Parker Bruce C.
Published: March 2008

The major C14‐labeled substance in sieve tube exudate of M. pyrifera is D‐mannitol, comprising 3.6% (w/v). No sugars are detectable. Certain amino acids also possess some CWabeling and occur in significantly high concentrations in exudate. The exudate contains negligible ether‐soluble lipid, but has a large amount of protein and a high concentration of K+. Neither protein nor lipid become labeled significantly in sieve tubes during short‐term translocation experiments with C14. In general the chemical composition of the assimilate stream is comparable to that of vascular plants and does not, consequently, necessitate a different mechanism for translocation.
THECATE HETEROPHIC DINOFLAGELLATES: FEEDING BEHAVIOR AND MECHANISMS1
Authors: Jacobson Dean M. , Anderson Donald M.
Published: March 2008

The feeding of 18 species of thrcale hetrophi dinoflagellates from three genera (Protoperidininm, Oblea, Zygabikodinium) can all be described within one general framework. These species engulf diatoms and other prey with a pseudopod (herein terned a “Pallium”)which originates at the flagellar pore in the sulcus. The pallium is a highly plastic, membranous organ which rasily strethes to accommodate spines and many as 58 diatom cells in a chain. The contents of the phytoplanklon prey are liquified and transporued throughthe pallioum typically within 7 to 30 minutes of capture (although feeding may last 2 h) teaving an intact but empty cell wall or frustule. Thus far, with few exceptions, Protoperidinium specises have been observed feeding inly on diatoms, whereas two diplopsaloid species feed on dinoflagellates and prasinophytes as well. In four species from the three genera studied. a capture filament has been observed that connects the food to the dinoflagellate prior to extension of the pallium, sometimes allowing the cell to pull the food while swimming. A distinctive precapture swimming behavior is also deseribed foe six species, suggesting that the dinoflagellates are selective grazers.
SPECIALIZATION OF ENDOPLASMIC RETICULUM ARCHITECTURE IN RESPONSE TO A BACTERIAL SYMBIOSIS IN PERIDINIVM BALTICUM (PYRRHOPHYTA)1
Authors: Chesnick Joby Marie , Cox Elenor R.
Published: March 2008

Transmission elrctron microscopy (TEM) and rapid freeze‐fracture analyses were used to provide data for a more accurate description of the relationship of Peridinium balticum (Levander) Lemmermann to endosymbiotic bacteria present in the dinoflagellate's cytoplasm. Bacteria were found in all of the cells observed and were present in both gamete and zygote life cycle stages. Analysis of micrographs showed that bacteria were tightly clustered in the posterior portion of the dinoflagellate cell in numbers of 50‐200/ section. Rapid freeze‐fracture replicas re‐vealed a specialization of the endoplasmic reticulum (ER). ER surrounded each bacterium and consisted of a series of infoldings which contacted the bacterial plasma membrane in several places. Extensions of ER were common between adjacent bacteria. We have interpreted the development and specialization of endoplasmic reticulum of the dinoflagellate host as an example of a cellular response of one organism to another, supportive of the serial endosymbiotic theory. Intramembrane particles (IMP) were seen on both protoplasmic (P) and exoplasmic (E) faces of the bacterial plasma membrane. Aquisition of the bacterial symbiont and the effects of long term culturing are discussed.
THE ULTRASTRUCTURE OF MEIOSPORES OF COLEOCHAETE PULVINATA (CHAROPHYCEAE)1
Authors: Graham Linda E. , Taylor Claude
Published: March 2008

In view of the relative importance of reproductive cell ultrastructure in phylogenetic and systematic studies of green algae, we investigated the fine structure of germinating zygotes and meiospores of Coleochaete pulvinata Braun. Meiospores have a flagellar apparatus very similar to that of zoospores and spermatozoids of the same species. Meiospores differ from zoospores and spermatozoids of C. pulvinata in having pyramidal body scales similar to those present on zoospores of C. scutata. Meiospores of C. pulvinata had as many as twice the number of spline microtubules as zoospores, and four times the number present in splines of spermatozoids of the same species. Developing meiospores of C.pulvinata, like those of other Coleochaete species, are individually surrounded by chamber walls. These differed from vegetative cell walls in lacking plasmodesmata. Moreover, the chamber walls in germinating zygotes of C.pulvinata stained a cobalt blue color with resorcinal blue, and fluoresced yellow in the presence of aniline blue, thus exhibiting the staining characteristics of callose. In location, morphology and presence of callose, chamberwalls resemble “special walls” of land plants, they may represent a charophycean spore development preadaptation useful in the evolution of walled spores characteristic of land
EFFECTS OF CO2 CONCENTRATION DURING GROWTH ON THE INTRACELLULAR STRUCTURE OF CHLORELLA AND SCENEDESMUS (CHLOROPHYTA)1
Authors: Miyachi Shigetoh , Tsuzuki Mikio , Maruyama Isao , Gantar Miroslav , Miyachi Shizuko , Matsushima Hisashi
Published: March 2008

Effects of CO2 concentration during growth on intracellular structure were studied with ftve species of Chlorella and Scenedesmus obliquus. Cells grown under ordinary air conditions (low‐CO2 cells) had a well developed pyrenoid surrounded by starch, while those grown under high CO2 conditions (high‐CO2 cells) had a less developed pyrenoid or no detectable pyrenoid. Two mitochondria, one at each side of the neck of the projection of the chloroplast close to the pyrenoid, were found in low CO2 cells of C. vulgaris 11h. Usually, lamellar stacks extended in parallel in the chloroplast of low‐CO2 cells of C. vulgaris 11h, while a grana‐like structure was found in high‐CO2 cells. However, in C. pyrenoidosa, grana like structures were found more commonly in low‐CO2 cells than in high‐CO2 cells. These results suggest that development of pyrenoid starch is generally correlated with growth under low CO2 conditions, whereas CO2‐effects on lamellar stacking are species dependent.
CELLULAR MOVEMENT IN THE CENTRIC DIATOMODONTELLA SINENIS1
Authors: Pickett‐Heaps Jeremy D. , Hill David R. A. , Wetherbee Richard
Published: March 2008

Cultured, actively growing cells ofOdentella sinensissecrete mucilage, forming gelatinous masses; the mucilage can be visualised with Alcian Blue. When examined live with the light microscope, many cells exhibited continuous small shuffing and rocking movements that could last for long periods (30‐40 min); the cells, however, were not translocated and remained relatively fixed in position with respect to their neighbours.

Ultrastructural examination of these cells showed prominent aggregations of mucilage vesicles, derived from the Golgi bodies, at the base of the labiate processes, each of which is close to an elevation bearing an ocellus. In Ditylum brightwellii, similar aggreations of these vesides were also located at teh labiate processes; this diatom, too, secretes mucilage but does not have ocelli. We conclude that the movements observed inO. sinenisisare an indirect result of active muilage secretion through the labiate process. It has been suggested that the raphe may have evolved from the labiate process; our conclusion, therefore, has phylogenetic implications, suggesting a functional as well as a morphological relationship between the two valve structures.
EFFECTS OF CURRENT VELOCITY AND LIGHT ENERGY ON THE STRUCTURE FO PERIPHYTON ASSEMBLAGE IN LABORATORY STREAMS1
Authors: Steinaman Alan D. , McIntire C. David
Published: March 2008

Effects of current velocity and light energy on the taxonomica and physiognomic characteristics of periphyton assemblages were investigated in laboratory streams. The initial rate of colonization was related to current velocity, while the effects of light energy accounted for differences in species composition by the end of the experiment. Although the laboratory systems had many species in common during the realy stages of colonization, the experimental treatments generated differences in rates of communitydevelopment. synedra spp. were the early coloniters of the substrate, followed by an understory of Achnanthes spp. After day 16, Stigeoclonium tenue developed in the streams exposed to the higher photon flux density, but was rare in the shaded streams. The applicability of traditional successional theory to develoopmental patterns in lotic periphyton assemblages is discussed.
OCCURRENCE OF RICHELIA INTACELLULARIS (CYANOPHYTA)WITHIN THE DIATOMMMS HEMIAULUS HAUKII ADN H. MEMBRANACEUS OFF HAWAII1
Authors: Heinbokel John F.
Published: March 2008

The presence of nitrogen–Fixing cyanobacterial endophytes, such as Richelia intracellularis Schmidit commonly observed within several species of Rhizosolenia, in nitrogen‐limited oceanic waters has obvious implications both for the host organism(s) and for the entire planktonic assemblage. Recently, epi‐fluorescent examination of pllankton samples collected off Oahu, Hawaii, in september 1982 revealed R. intracellularis within the diatoms Hemiaulus membranaceus Cleve and H. hauckii Grunow as well as its expected presence within Rhizosolennia spp. Richelia intracellularis coccurred with within Hemiaulus spp. at frequenccies (ca.80%)comparable to those noted for Rhizosolenia spp. Standard bright field or phaseconrast microsocopy could not reliably distinguish the cyanobacteria within Hemiaulus spp. If this association is common, the occurrence of R.intracellularis (and its significance in the nitrogen dynamics of the ocean)may have been greatly underestimated in previous studies.
THE FLAGELLAR APPARATUS OF GYMNODINIUM SP. (DINOPHYCEAE)1
Authors: Roberts Keith R.
Published: March 2008

The detailed structure of the flagellar apparatus has been determined in a small dinoflagellate of the genus Gymnodinium. Although diminutive, this dinoflagellate possesses a complex flagellar apparatus consisting of a posteriorly directed microtubular root, a transverse striated fibrous root, several striated fibrous connectives that attach the basal bodies to one another as well as to the different roots, and a conspicuous non‐striated fibrous connective that directly links the posteriorly directded microtubular root with the extended lobe of the nucleus. This represents the second discovery of a nuclear connective linked to the flagellar apparatus in the Dinophyceae but is the first report to elucidate the spatial relationships of the connective with the flagellar apparatus and the cell. A detailed diagrammatic reconstruction is provided and the similarities between these flagellar apparatus features are compared with those known for other dinoflagellates. Additionally, the structure and displacement of the nuclear connective are compared with nuclear connectives described in other protists.
ULTRASTRUCTURE OF MEIOSIS INDASYA BAILLOUVIANA(RHODOPHYTA). II. PROMETAPHASE I—TELOPHASE II AND POST‐DIVISION NUCLEAR BEHAVIOR1
Authors: Broadwater Sharon , Scott Joe , Pobiner Bonnie
Published: March 2008

This is the second of two papers which together are the first comprehensive ultrastructural report of meiosis in a red alga. Many details of the meiotic process inDasya baillouviana (Gmelin) Montagne are the same as those reported previously for mitotic cells in ceramialian red algae, but several characteristics seem unique to meiotic cells. The nucleus and nucleolus of meiotic cells are larger than those of mitotic cells and large accumulations of smooth ER are often found at the division poles during meiosis 1. The function of the ER accumulations is unknown. Importantly, both interkinesis and a simultaneous division of two separate nuclei during meiosis II was demonstrated. These new observations fail to support earlier speculation on higher red algae for a “uninuclear” meiosis (both nuclear divisions within the same nuclear envelope). However, following meiosis II the four nuclei migrate centripetally and possibly fuse in the center of the tetrasporangium. This post‐division nuclear maneuvering is not understood, but our interpretation accounts for the earlier and erroneous impression of “uninuclear” meiosis. Perhaps the most important aspect of meiosis observed inDasya isits basic adherence to the pattern commonly seen in higher plants and animals. This conservatism of the meiotic process lends further skepticism to the belief that red algae are extremely “primitive” organisms, although they undoubtedly represent a very “ancient” group of eukaryotic plants.
GENETICS OF CHAMPIA PARVULA (RHODYMENIALES. RHODOPMYTA): MENDELIAN INHERITANCE OF SPONTANEOUS MUTANTS1,2
Authors: Steele Richard L. , Thursby Glen B. , van der Meer John P.
Published: March 2008

Spontaneous mutants affecting the morphology and pigmentation of the small marine red alga Champia parvula were genetically characterized. All of the variants were transmitted in the Mendelian pattern expected for recessive nuclear mutations. The results permit the identification of four mutant genes affecting morphology and four mutant genes affecting pigmentation. One of the latter, designated yell, was interesting in that it also appeared to act as a recessive lethal during carposporophyte development. So linkage bas been discovered in crosses conducted thus far. Champia parvula was found to have many desirable features for genetic studies, especially a very rapid sexual life cycle, and it is suggested that this species should be considered as a possible model organism for future genetic studies on the Rhodophyta or for teaching seaweed genetics.
DESM1D ZYGOTES IN EAST TEXAS1
Authors: Smith Betsy B.
Published: March 2008

In an extensive survey for desmids in 217 lakes and ponds in 21 counties of east Texas, desmid zygotes were infrequently encountered. A list is given of zygotes of 22 species in 9 genera. Two zygotes previously unobserved are described and illustrated in photographs and camera lucida drawings.
EXOGENOUS STEROIDS AND GROWTH OF NEOSPONGIOCOCCUM SP. (CHLOROPHYTA)1
Authors: Hardy Mark G. , O'Kelley Joseph C.
Published: March 2008

Of the various types of steroids found in nature, only sterols (steroids whose molecules possess an 8‐ to 10‐carbon atom hydrocarbon side chain at position 17 of the perhydrocyclopentanophenanthrene ring) are known to be common constituents of algae. Little is known of the effects of steroids in the environment upon the growth and survival of algae. This paper investigates the growth of the green alga Neospongiococcum sp. in medium containing steroids. Bile acids are not inhibitory, even at a concentration of 100 ppm. Some sterols inhibit growth when present in the medium at a concentration of 100 ppm, but not at 10 ppm. Testosterone and β‐estradiol, which have no carbon atom side chain at ring position 17, inhibit growth at a concentration of only 10 ppm. Steroids whose molecules possess a 2‐carbon atom side chain at ring position 17 and a keto group at the α‐carbon of this side chain, such as pregnenolone, inhibit growth at a concentration of as little as 1 ppm. Respiration is also inhibited by pregnenolone at this level.
NUTRITIONAL REQUIREMENTS FOR SEXUAL REPRODUCTION INMESOTAENIUM KRAMSTAI(CHLOROPHYTA)1
Authors: Tiflickjian John D. , Raybum William R.
Published: March 2008

Optimum conditions for conjugation in the heterothallic saccoderm desmid Mesotaenium kramstai Lemmer‐mann have been determined. In culture, cells acquired the ability to form gamete pairs just prior to the onset of stationary phase after sufficient nitrate had been depleted from the medium. The appearance of potential gametes was delayed by increasing the concentration of KNO3When cells of both mating types were harvested from 15 to 18 day old cultures, washed, resuspended in fresh medium, and mixed, approximately 50 percent of the cells paired (measured three days after mixing) in a medium containing 0.13 mM or less KNO3. At greater concentrations, fewer pairs formed; no pairs formed in medium containing 0.5 mM KNO3. Conjugation was not inhibited by other macronutrients.

Calcium and magnesium were essential for maximum conjugation. Although Ca2+and Mg2+contentrations of 0.05 mM and 0. I mM, respectively, were sufficient for optimum growth, maximum conjugation required more than 10 times these values. Few gamete pairs formed when either Ca2+or Mg2+was omitted from the medium, no pairing occurred when both Ca2+and Mg2+were omitted.
IRRADIANCE, DAYLENGTH AND TEMPERATURE EFFECTS ON ZOOSPOROGENESIS IN COLEOCHAETES CUTATA (CHAROPHYCEAE) 1
Authors: Graham Linda E. , Graham James M. , Kranzfelder James A.
Published: March 2008

Using a factorial design, we investigated the effects of 150 different combinations of irradiance, daylength and temperature on zoosporogenesis in Coleochaete scutata. Analysis of variance (ANOVA) revealed that irradiance and daylength did not .significantly influence the response, out that temperature was highly significant. Exposure of thalli to 20°C for one to several days is sufficient to induce zoospore production in C. scutata and several other northern temperature species of Coleochaete. Results of the factorial experiment correlate well with field observations on the seasonal occurrence of asexual reproduction in several Coleochaete species. A technique based on results of this factorial study is described for using zoospores to obtain morphologically normal, unialgal cultures of Coleochaete .sp. It was concluded that the factorial approach to investigation of environmental control of zoosporogenesis can be a powerful tool for understanding natural algal population dynamics, as well as controlling growth and reproduction of algae in the laboratory.
GROWTH, PHOTOSYNTHESIS AND MAINTENANCE METABOLIC COST IN THE DIATOM PHAEODACTYLUM TRICORNUTUM AT VERY LOW LIGHT LEVELS 1
Authors: Geider Richard J. , Osbonie Bruce A. , Raven John A.
Published: March 2008

The compensation point for growth of Phaeodactylum tricornutum Bohlin is less than 1 μmol. m−2s−1. Growth at low PFDs (<3.5 μmol. m−2.s−1) does not appear to reduce the maximum quantum efficiency of photosynthesis (øm) or to greatly inhibit the potential for light‐saturated, carbon‐specific photosynthesis (Pmc). The value for øm in P. tricornutum is 0.10–0.12 mol O2‐mol photon−1, independent of acclimation PFD between 0.75 and 200 μmol.m−2.s−1 in nutrient‐sufficient cultures. Pmc in cells of P. tricornutum acclimated to PFDs <3.5 μmol m−2−s−1 is approximately 50% of the highest value obtained in nutrient‐sufficient cultures acclimated to growth‐rate‐saturating PFDs. In addition, growth at low PFDs does not severely restrict the ability of cells to respond to an increase in light level. Cultures acclimated to growth at lees than 1% of the light‐saturated growth rate respond rapidly to a shift‐up in PFD after a short initial lag period and achieve exponential growth rates of 1.0 d−1 (65% of the light‐ and nutrient‐saturated maximum growth rate) at both 40 and 200 μmol.m−2.s−1
ELECTROPHYSIOLOGICAL INVESTIGATIONS OF THE RED ALGA GRIFFITHSIA PAGIFIG AKYL. 1
Authors: Bauman Robert W. , Jones Bradley R.
Published: March 2008

The membrane potentials of the plasmalemma and tonoplast in Griffithsia pacifica Kyl were measured and shown to be significantly different. No consistent cell wall potential was discovered. Adjacent cells in the filament were demonstrated to be electrolonically coupled with a mean coupling coefficient of 0.13. Cobaltions did not move between cells. No dye coupling was seen using the fluorescent dye Lucifer yellow CH. These observations provide new information on the electrophysiology of red algae and indicate that there is intercellular continuity between the cells of a filament of Griffithsia pacifica.
DARK CARBON FIXATION STUDIES ON THE INTERTIDAL MACROALGA ASCOPHYLLUM NODOSUM (PHAEOPHYTA) 1
Authors: Johnston Andrew M. , Raven John A.
Published: March 2008

The characteristics of dark carbon fixation by Ascophyllum nodosum were investigated. In longitudinal profile the maximum rates of dark and light dependent fixation are found at the apex. The use of Michaelis‐Menten kinetics did not suitably describe the relationship between the uptake rate in the dark and the total inorganic carbon concentration. Dark fixation was saturated at a total inorganic carbon concentration [TIC] of 2.5 mM. The use of the Hill‐Whittingham equation to describe the uptake curve indicates that the process is diffusion limited. Comparisons of dark fixation at high (8.0) and low (5.2) pH suggest that bicarbonate ions are used as a source of inorganic carbon. The transfer of 14C, fixed in the dark, from the ethanol soluble to the insoluble fraction was relatively slow irrespective of the light treatment during the chase period. Ascophyllum nodosum displays a small diel fluctuation in the pH of aqueous extracts and titratable acidity similar to that displayed by CAM plants. The significance of dark fixation to the overall carbon budget is discussed.
A POLYPLOID SPECIES COMPLEX OF SPIROGYRA COMMUNIS (CHLOROPHYTA) OCCURRING IN NATURE 1
Authors: Wang Jen‐Chyong , Hoshaw Robert W. , McCourt Richard M.
Published: March 2008

Investigations were conducted to determine whether ploidal changes found in laboratory cultures of Spirogyra also occur in nature. In an earlier study filament types identifiable as three different species (Spirogyra singu‐laris Nordstedt, S. communis (Hassall)Kütz., S. fragilis Jao) arose from an original clonal culture through vegetative growth and sexual reproduction. These three “species” or filament groups differed in filament width, chloroplast number, zygospore size, and chromosome number. The differences in chromosome number represented a polyploid series of diploid (S. communis), triploid (S. fragilis), and tetraploid (S. singularis) forms in which width increased with ploidal level. The three width groups constituted a “species complex.” Five years after isolation of the original strain in this species complex, filaments corresponding to two of the width groups (S. singularis and S. communis) were found at the original collection site in the Santa Catalina Mountains in southern Arizona. The two field‐collected groups were indistinguishable from the laboratory species complex in morphology and chromosome number. Homothallic conjugation within the two field width groups yielded progeny similar to those from homothallic conjugation of groups in the laboratory species complex. Filament widths of progeny were generally within the width limits of respective parental groups. The four possible intergroup crosses between the two laboratory and two field width groups yielded progeny similar to the wider parent (S. singularis) or the parent of intermediate width (S. fragilis). Progeny characteristics were determined by the width groups of parents, regardless of whether parents came from the laboratory or field. The similarities in morphology, chromosome numbers, and reproductive behavior of laboratory and field width groups imply that the laboratory species complex of S. communis has a natural counterpart in the field.
IRON‐MEDIATED CHANGES IN THE GROWTH OF LAKE ERIE PHYTOPLANKTON AND AXENIC ALGAL CULTURES1
Authors: Storch Thomas A. , Dunham Valgene L.
Published: March 2008

The effect of iron enrichment on algal growth and photosynthesis was investigated using natural assemblages of Lake Erie phytoplankton and axenic cultures of Anabaena, Scenedesmus and Selenastrum. Cell yield and photosynthesis were frequently inhibited in the presence of unchelated iron over the range of 3.6 to 53.7 μM iron as FeCl3. In lake water and in a defined medium with low nutrient concentrations, the degree of inhibition by iron could be reduced by chelating the iron with EDTA or by enriching the cultures with phosphorus. Chemical analyses revealed that the EDTA efectively reduced the ability of the ferric iron to remove soluble phosphorus from the media. EDTA was also observed to reduce rather than enhance iron uptake by axenic cultures of A. flos‐aquae. These data support the hypothesis that additions of EDTA to low‐nutrient media may serve to stimulate algal growth in the presence of iron by preventing the iron from altering extracellular concentrations of soluble ions essential for algal metabolism. In medium with high nutrient concentrations, the soluble phosphorus concentration was not appreciably altered by either EDTA‐chelated or unchelated iron enrichment (0.9 to 53.7 μM). Instead, the observed enhancement of cell yield by EDTA‐chelated iron in nutrient‐rich media appeared to be due to the direct effect of iron on intracellular metabolic processes.
GROWTH OF COLPOMENIA PEREGRINA (PHAEOPHYCEAE) IN CULTURE: EFFECTS OF SALINITY, TEMPERATURE AND DAYLENGTH1
Authors: Vandermeulen Herbert
Published: March 2008

Increases in size of Colpomenia peregrina (Sauv.) Hamel microthalli were determined at six different combinations of salinity and temperature under laboratory conditions. Microthalli grown at low salinity (15%) did not have a growth rate significantly different from microthalli grown at high salinity (30%). However, more macrothalli were produced in higher salinity media. Fewer macrothalli were produced at lower temperatures.

Growth of C. peregrina microthalli was also determined at six different combinations of daylength and temperature. Microthalli under 15:9 h (LD cycle) did not have a growth rate significantly different from microthalli under 9:15 h LD. However, more macrothalli were produced under long day conditions. Of the three different temperatures utilized (5, 13 and 20° C) only 5° C produced significantly different growth rates. Low temperature reduced growth to such an extent that macrothalli of a size that could be recognized in the field took approximately two months to produce in culture. These results may explain the seasonal presence/absence of the delophycean phase of C. peregrina in the field.

Zoospore survivorship and macrothallus production of C. peregrina in culture indicated that both PES and an artificial medium were suitable for the laboratory cultivation of this plant.
GENETICS OF GRACILARIA TIKVAHIAE (RHODOPHYCEAE). XI. FURTHER CHARACTERIZATION OF A BISEXUAL MUTANT1,2
Authors: van der Meer John P.
Published: March 2008

A spontaneous bisexual mutant of Gracilaria tikvahiae McLachlan has been further characterized. Female plants that are carriers for the mutation, but do not themselves express bisexuality, have been identified among progeny derived from the original bisexual male plant. In crosses to normal males these carrier females yielded normal tetrasporophytes which in the subsequent gametophyte generation produced a 2 female: 1 male: 1 bisexual segregation. In crosses to bisexual males the carrier females produced unusual tetrasporophytes that formed cystocarps in addition to tetraspores. The gametophyte generation obtained from the tetraspores of these tetrasporophytes included only females and bisexuals, these being present in a 1:1 ratio. Other crosses, using bisexual male progeny, indicated that these have the same characteristics as the original bisexual mutant. All of the results are consistent with the genetic interpretation made previously that bisexuality results from a single recessive mutation, designated bi, in a gene distinct from the mt locus controlling male vs. female differentiation. From the phenotypes that have been observed it appears that the mutation does not cause bisexuality per se but rather results in unregulated female expression in males and tetrasporophytes where female‐specific genes are normally repressed. It is suggested that the normal bi+ allele plays an important role in that repression process.

The origin of the bisexual mutation has been re‐examined by studying the progenitor stock of the mutation and stocks related to it. It appears that the bisexual mutation arose in a two‐step process, first to a low level of expression that is found in the progenitor stocks and then to the high level of expression found in mutant clone 1045(bi) and its descendants.
MORPHOLOGICAL VARIABILITIES OF THREE CLOSELY RELATED MATING GROUPS OF CLOSTERIUM EHRENBERGII MENEGHINI (CHLOROPHYTA)1
Authors: Kasai Fumie , Ichimura Terunobu
Published: March 2008

The ranges of morphological variabilities in vegetative cells of three closely related mating groups of Closterium ehrenbergii Meneghini were statistically analyzed, having been grown under standard and uniform culture conditions, using Group A clones from Japan and Australia, Group B clones from Japan and Taiwan and Group H clones from Nepal. Significant differences in the morphological characters were not recognized between the two complementary mating types in any of the three groups. It has been shown that cells of Group A are smallest (mean width 50 μm and mean length 250 μm) and cells of Group B are largest (mean width 67 μm and mean length 404 μm), while cells of Group H are intermediate (mean width 57 μm and mean length 333 μm). There are considerable differences in the mean cell size between the three mating groups, although some intergrading clones were recognized. Degrees of the intergrading overlap were shown to be small between the sympatric groups (A and B) and large between the two pairs of allopatric groups (A and H & B and H). It has been shown that cells of Group A are shorter and much more curved than cells of the other two mating groups. Cells of Groups B and H are slender and less curved. It has also been shown that the ranges in cell size of each mating group are smaller than those currently accepted for C. ehrenbergii.
ULTRASTRUCTURE OF MALE GAMETES OFSPHAEROPLEA ROBUSTA(CHLOROPHYCEAE)1
Authors: Buchheim Mark A. , Hoffman Larry R.
Published: March 2008

Male gametes have been studied in Sphaeroplea robusta (Chlorophyceae) using both light and electron microscopy. Mature gametes are typically biflagellate and possess a single, large mitochondrion that dominates the anterior third of the cell, directly posterior to the basal bodies. One or more microbodies are closely associated with the mitochondrion. Contractile vacuoles occur anterior to the elongated nucleus which, in fully mature gametes, possesses condensed chromatin. The reduced, starch‐filled chloroplast lacks an associated eyespot and occupies a posterior position. A thin, anteriorly directed process or extension of the chloroplast parallels a portion of one of the multistranded flagellar roots. The paired basal bodies are directly opposed with no demonstrable offset, and are connected by an arched distal fiber with a highly elaborated central striated region that forms the apical cone, a feature characteristic of male gametes in most species of Sphaeroplea. Possession of a striated distal fiber, a cruciate flagellar root system (i.e. two‐stranded microtubular roots alternating with multistranded roots), and directly opposed basal bodies are consistent with the alga's chlorophycean affinities.
COMPONENTS OF PHOTOSYNTHESIS IN THE INTERTIDAL SACCATE ALGA HALOSACCION AMERICANUM (RHODOPHYTA, PALMARIALES)1
Authors: Oates Brian R.
Published: March 2008

Rates of photosynthesis for the intertidal saccate alga Halosaccion americanum Lee were determined under submersed and emersed conditions. By fitting the data to a hyperbolic tangent function, P max was 4.08 mmol CO2. m−2. h−1 and Ik was 116.4 μE. m−2. s−1. under submersed conditions. Under emersed conditions, P max was 1.89 mmol CO2. m−2. h−1 and Ik was 22.9 μE. m−2. s−1. Dark fixation represented 3.7% of Pmax in submersed thalli, whereas it equalled 33.3% of Pmax in emersed thalli. Photosynthetic uptake from the thallus cavity represented a significant source of carbon, achieving 68.8% of that from the atmosphere and 29.4% of that from seawater. Retained seawater also greatly reduced drying under emersed conditions. Experimental thalli lost 70.4% of their water after 120 min under desiccating conditions, whereas control thalli lost only 6.3%. Emersed photosynthetic rates were enhanced by desiccation, At times, rates for desiccated thalli were two times those of fully‐hydrated ones. Only after water loss exceeded 47% did photosynthetic rates fall below fully‐hydrated rates. Utilizing data from this study a model was constructed to determine total photosynthetic production of H. americanum over a single daylight period. These caluclations demonstrate that photosynthetic contributions from emersed photosynthesis and retained seawater are significant. Because production from all sources is almost equal, total photosynthesis over a single day does not change greatly regardless of the time spent in air or in water.
NUTRIENT AND LIGHT LIMITATION OF ALGAE IN TWO NORTHERN CALIFORNIA STREAMS1
Authors: Hill Walter R. , Knight Allen W.
Published: March 2008

Nutrient‐diffusing subsrates were used to investigate nutrient limitation of attached algal assemblages in a shaded stream and an unshaded stream in northern California. Water from both streams contained low levels of nitrogen (< 14 μg.L−1) and very low N:P ratios (< 2). After 31 days of colonization and growth, attached algal biomass on nitrate‐diffusing substrates was significantly greater than on control substrates in the unshaded stream. Nitrate‐diffusing substrates also supported larger numbers of grazing insects in the unshaded stream. The prostrate diatoms Achnanthes lanceolata Bréb. and Coconeis placentula Ehr. displayed the most consistent positive responses to nitrate enrichment. Nutrient enrichment did not increase the accrual of algal biomass in the shaded stream, but algal biomass was significantly greater at sites located under openings in the tree canopy, implicating light as a limiting factor in this stream. Several Navicula and Nitzschia species, and one unidentified Gomphonema species, were positively associated with higher light levels in the shaded stream. Shade appears to be the primary factor limiting algal growth in small northern California streams, but when its effect is reduced by logging, the inherently low levels of nitrogen in these streams can become limiting.
ULTRASTRUCTURE OF THE GAMETE OFPEDIASTRUM DUPLEX(CHLOROPHYCEAE)1
Authors: Wilcox Lee W. , Floyd Gary L.
Published: March 2008

Gametes of Pediastrum duplex Meyen were investigated ultrastructurally, with emphasis on the flagellar apparatus. The cells are naked, biflagellate, and measure approximately 2.5 × 8 μm. Distinguishing them from zoospores is their possession of an eyespot and mating structure (the apical cap), and their lack of the peripheral band of cytoplasmic microtubules involved in colony formation. Four featurs of the flagellar apparatus are especially noteworthy: (1) the basal bodies are directly opposed and (2) are interconnected via their cores, (3) the central portion of the distal fiber is elaborated into an unusual ribbed structure which overlies the striated microtubule‐associated component (SMAC) of the two‐membered rootlets, and (4) the X‐rootlets are dissimilar in microtubular number. The smaller X‐rootlet consists of four microtubules in a three over one (3/1) configuration, whereas the larger has been found to be either 5 / 1, 6 / 1 or 7 / 1. The former rootlet extends past the nucleus whereas the latter extends down the opposite side of the cell, passing near the eyespot. The first two of these flagellar apparatus features have been previously noted in other motile cells of the Hydrodictyaceae. Although not specifically mentioned, published micrographs suggest the presence of the latter two as well, which may indicate that all four flagellar apparatus features are characteristics of all motile cells in the Hydrodictyaceae.
SIMILAR UNSTABLE MUTATIONS IN THREE SPECIES OF GRACILARIA (RHODOPHYTA)1
Authors: van der Meer John P. , Zhang Xuecheng
Published: March 2008

Unstable mutants with similar variegated pigmentation were genetically characterized in the red algae. Gracilaria tikvahiae (McLachlan), G. foliifera (Forsk.) Børg. and. G. sjoestedtii (Kylin). All three mutants were green plants with flecks of red tissue where cells had reverted to wild type. The mutant green phenotypes were all recessive, and their genetic behavior in crosses indicated that each was the result of a single, unstable, nuclear gene. Wild‐type revertant tissue was stable one it arose. Revertant plants obtained from spores and revertant fronds taken from variegated plants could not be distinguished from the normal wild type, either phenotypically or genetically. Reversion to wild type occurred during all phases of the life cycle. In crosses between the mutants and wild type, most of the F1 tetrasporophytes were heterozygous wild‐type plants, an observation consistent with the recessive nature of the mutations; however, a low frequency of homozygous unstable‐green F1 tetrasporophytes was also obttained from these crosses. The molecular basis of neither the mutant instability, i.e. the reversion to wild type, nor of the process producing the unstable green F1 tetrasporophytes can yet be deduced, but the phenotype of the plants and genetic results suggest the involvement of transposable genetic elements.
THE TIME‐COURSE OF PHOTOADAPTATION TO LOW‐LIGHT IN PROROCENTRUM MARIAE‐LEBOURIAE (DINOPHYCEAE)1
Authors: Harding Lawrence W.
Published: March 2008

The estuarine dinoflagellate, Prorocentrum mariaelebouriae (Parke & Ballantine 1957) Faust 1974 undergoes increases in pigmentation and photosynthetic efficiency within several days of downward light shifts. These changes can be described by first‐order kinetics, as has been reported previously for Chlorophyll (Chl) a in several phytoplankton species. The studies described in this paper were conducted with isolates of populations of Prorocentrum from the Chesapeake Bay. We determined rates of adaptation to low‐light for cultures grown at a range of photon flux densities (I0= 2.65–26.2 E.m−2, d−1, shifted to 6.3–7.0% I0) at three temperatures (10°, 15°, and 20° C), bracketing the conditions this species experiences in situ. In this paper, I report the time‐course of changes in α, Pmax Chl a, peridinin, and Ik and first‐order rate constants, K1 for changes in α, Chl a and peridinin. cell−1. K1 for changes in α cell−1 averaged 1.58 × 10−2 h−1 for conditions encompassing five light treatments and three temperatures; the corresponding mean for Chl a was 1.59 × 10−2 h−1. Increases in peridinin measured for five light treatments at 15° C showed a mean K1 of 1.22 × 10−2 h−1, Average percent changes in per cell α, Chl a, and peridinin ranged from 0.4–4.0% h−1 (10–90% d−1) following exposure to low‐light. Photoadaptive changes are important to Prorocentrum because in nature it occupies turbid waters (Kt≥ 0.5 m−1) where the mixing depth often exceeds the depth of the photic layer. Cells are entrained beneath a seasonally‐stable density discontinuity and are exposed to very low‐light (< I E.m−2.d−1) for days to weeks during subpycnocline transport. The ability of this species to undergo changes in pigmentation and photosynthetic physiology confers increased efficiency of light harvesting and contributes to this species’survival in the estuary where it is an important component of the dinoflagellate flora.
PHYSIOLOGICAL CHARACTERIZATION OF SIX LIPID‐PRODUCING DIATOMS FROM THE SOUTHEASTERN UNITED STATES1
Authors: Tadros Mahasin G. , Johansen Jeffrey R.
Published: March 2008

Six strains of diatoms from intertidal waters were isolated as part of the SERI Aquatic Species Program collection and screening effort: Amphiprora hyalina Greville, Cyclotella cryptica Reimann, Lewin & Guillard, Navicula acceptata Hustedt (two strains, NAVIC6 and NAVIC8), Navicula saprophila Lange‐Bertalot & Bonik, and Nitzschia dissipata (Kütz.) Grunow. Among numerous algal strains isolated as part of this collection effort, these six strains showed rapid growth and elevated lipid content in preliminary screening experiments and were chosen for further physiological characterization. N. dissipata grew most rapidly at 25°C, whereas the other five strains grew best at 30–35°C. Salinity tolerance varied among strains, with maximal growth occurring at the following conductivities: 10–60 mS.cm−1 (A. hyalina and N. acceptata NAVIC8), 10–35 mS.cm−1 (C. cryptica), 20–45 mS.cm−1 (N. acceptata NAVIC6), 10 mS.cm−1 (N. saprophila), and 20–35 mS.cm−1 (N. dissipata). The diatoms also differed in their utilization of nitrogen sources with A. hyalina growing optimally with either nitrate or urea; N. acceptata NAVIC6, with either nitrate or ammonium; C. cryptica, N. acceptata NAVIC8, and N. dissipata, with nitrate; and N. saprophila, with urea. Under optimal conditions, A. hyalina grew at 2.0 doublings. day−1; C. cryptica grew at 3.0 doublings. day−1. Each Navicula strain had a growth rate of 3.8 doublings. day−1, and N. dissipata grew at 2.6 doublings.day−1. All six strains had lipid contents in excess of 37% ashfree dry weight (AFDW) under nutrient‐limited conditions, with N. saprophila having the highest lipid content at 48% AFDW.
LOTIC ALGAL COMMUNITIES IN THE MT. ST. HELENS REGION SIX YEARS FOLLOWING THE ERUPTION1
Authors: Steinman Alan D. , Lamberti Gary A.
Published: March 2008

A survey of 21 lotic habitats from the Mt. St. Helens region, Washington, was conducted during late summer 1986, six years after the eruption. A total of 152 taxa was observed (94 diatoms, 36 chlorophytes, 19 cyanophytes, 2 xanthophytes, and I rhodophyte). Sampling sites were classified by TWINSPAN (two‐way indicator species analysis) and ordinated by DECORANA (detrended correspondence analysis). In general, both techniques corresponded well with each other and grouped sites according to the intensity of disturbance that they experienced. Species richness and diversity values tended to be lowest at the most heavily disturbed sites. Chlorophyll a values ranged over two orders of magnitude and tended to be higher at sites sampled from small, low‐discharge tributaries. Loowit Creek, a thermally influenced stream that begins within the volcanic crater, was dominated by thick mats of the cyanophyte Mastigocladus laminosus. A general comparison of the present study with one conducted just after Mt. St. Helens erupted suggests that successional processes are operating in these lotic algal communities.
ULTRASTRUCTURE OF THE ZOOSPORES AND VEGETATIVE CELLS OF TETRAEDRON AND CHLOROTETRAEDRON (CHLOROPHYCEAE)1
Authors: Watanabe Shin , Floyd Gary L. , Wilcox Lee W.
Published: March 2008

The flagellar apparatus of the zoospores of Tetraedron bitridens Beck‐Mannagetta and Chlorotetraedron polymorphum MacEntee, Bold et Archibald includes directly opposed basal bodies, a distal fiber that is elaborated into a ribbed structure to which the continuous striated microtubule‐associated component (SMAC) is connected, and partial caps over the proximal end of each basal body. The angle between basal bodies ranges from approximately 25° to 150°. Basal bodies at wider angles are interconnected via their cores. A septum is present in the B‐tubule of one basal body triplet in C. polymorphum. Both organisms have four microtubular rootlets arranged in a cruciate pattern. The two X‐membered rootlets in a single cell have dissimilar numbers of microtubules. In C. polymorphum there are 5 and 6 microtubules in a 4/1 and 5/1 arrangement. 3/1 and 4/1 rootlets are present in T. bitridens. Zoospores of T. bitridens have a fuzzy coat whereas those of C. polymorphum are naked. Pyrenoids in both species are covered by a continuous starch sheath. Vegetative, interphase cells of C. polymorphum have two centrioles connected by a fiber that are located in depressions in the nuclear envelope. We propose that these two genera may be closely related to Neochloris, and that the coenobial genera Hydrodictyon, Pediastrum and Sorastrum are derived from a Tetraedron‐like alga.
ULTRASTRUCTURAL FEATURES OF MITOSIS IN PLOEOTIA COSTATA (HETERONEMATALES, EUGLENOPHYTA)1
Authors: Triemer Richard E. , Fritz Lawrence
Published: March 2008

The ultrastructural features of mitosis in the colorless phagotrophic euglenoid, Ploeotia costata (Farmer and Triemer 1988bn; syn: Serpenomonas costata, Triemer 1986) are described. During interphase the nucleus is rounded and lies adjacent to the reservoir and the four basal bodies, two of which bear flagella. At the onset of mitosis, two additional flagella are generated from the accessory basal bodies such that four basal bodies with flagella now lie at one pole of the prophase nucleus. Microtubules develop in the nucleus prior to migration of one of the basal body pairs to the opposite pole of the nucleus. By metaphase, chromosomes with layered kinetochores are aligned on the equator of the spindle, and a dumbbellshaped nucleolus stretches from pole to pole. Continued elongation of the nucleus results in the separation of the chromosomal masses at anaphase. The distance between the nuclear poles from metaphase to anaphase changes little although the overall length of the nucleus nearly doubles. By telophase a large interzonal spindle develops between the forming daughter nuclei. The extended interzonal spindle breaks near the center prior to cell cleavage.