bluuebunny/crossref_metadata_2025_split huggingface dataset:
FUNGAL CELLWALL POLYSACCHARIDES ELICIT AN ANTIFUNGAL SECONDARY METABOLITE (PHYTOALEXIN) IN THE CYANOBACTERIUM SCYTONEMA OCELUTUM2
Authors: Patterson Gregory M. L. , Bolis Christine M. 
Published: October 2004

ABSTRACT The addition of fungal cell‐wall homogenates of Penicillium notatum and Cylindrocladium spathiphylli markedly stimulated the accumulation of tolytoxin, an antifungal secondary metabolite, in cultures of the cyanobacterium Scytonema ocellatum Lyngbye ex Bornet et Flahault. Evaluation of polysaccharides, proteins, and other polymers established that a limited range of polysaccharides, especially chitin and carboxymthylcellulose, selectively elicited enhanced tolytoxin accumulation in S. ocellatum. The elicitor activity of fungal cell‐wall preparations could be correlated with the chitin content of the preparation. Polymeric chitin was half‐maximally effective at a concentration (EC50) of 19 mg.L‐1, whereas chitin oligoments were more effective (EC50= 3.3 mg.L‐1) in eliciting enhanced tolytoxin accumulation. The elicitor activity of either purified chitin or an elicitor‐active fungal cell‐wall preparation could be destroyed by treatment with chitinase. The results suggest an ecological role for tolytoxin as an inducible chemical defense agent (phytoalexin) capable of protecting S. ocellatum against fungal invasion.
AGLAOTHAMNION HALLIAE COMB. NOV. AND A. COLLINSII SP. NOV. (CERAMIALES, RHODOPHYTA): RESOLUTION OF NOMENCLATURAL AND TAXONOMIC CONFUSION
Authors: Aponte Nilda E. , Ballantine David L. , Norris James N. 
Published: October 2004

ABSTRACT Specimens from the exsiccatae Phycotheca BorealiAmericana number 698 are shown to represent two distinct species. One of them, formerly known as Callithamnion halliae, is transferred to Aglaothamnion on the basis of its uninucleate cells. The specimens exhibit distichous branching and are ecorticate. A lectotype is proposed for one of the P.B.‐A. #698 specimens displaying these characters. Aglaothamnion halliae (Collins) comb. nov. is an earlier name for Aglaothamnion westbrookiae Rueness et L'Hardy‐Halos. The second species, together with specimens of P.B.‐A. #1896, has radial branching and corticated axes and is described herein as a new species, Aglaothamnion collinsii. The binomial Aglaothamnion boergesenii (Aponte et Ballantine)L'Hardy‐Halos et Rueness in Aponte, Ballantine, et J. Norris is validated. A key to the tropical and warm‐temperate western Atlantic species of Aglaothamnion is presented.
THE NEW GENUS AND SPECIESOSSIELLA PACIFICA(GRIFFITHSIEAE, RHODOPHYTA) FROM HAWAII AND NORFOLK ISLAND, PACIFIC OCEAN
Authors: Millar Alan J. K. , Abbott Isabella A. 
Published: October 2004

ABSTRACTOssiella pacificagen. et sp. nov. is described from sub tidal habitats (5–19 m) in the central (Hawaiian Islands) and southwestern (Norfolk Island) Pacific Ocean. Plants consist of limited prostrate axes that rapidly become erect and form ecorticate, subdichotomously branched axes bearing up to seven (mostly six) di‐/to trichotomously branched, pigmented, determinate, quickly caducous whorled laterals from subapical axial cells. Two to five tetrasporangza are borne directly on the inflated basal cells of pigmented determinate laterals. One to two spermatangial fascicles are similarly placed in male plants. Subapical procarps are borne on a three‐celled fertile axis, which occupies the same position as an indeterminate branch, being itself displaced laterally by the continued growth of the indeterminate axis. Procarps are bicarpogonial, the sterile cell normally associated with the supporting cell in procarps of the Griffithsieae being converted into a functional four‐celled carpogonial branch. Ossiellais compared with the other membus of the tribe, and a dichotomous key to the genera is offered. On morphological grounds, Ossiellaseemingly forms a perfect intermediary link along the phylogenetic lineage between the eastern Australian genusBaldockiaA. Millar, the eastern American genusCalliclavulaG. W. Schneid, and the widespreadAnotrichiumNägeli.
CHARACTERIZATION OF MYHOGRAMME LNIDA, MYRIOGRAMMEAE TRIB. NOV (DELESSEIUACEAE, FWODOPHYTA)
Authors: Hommersand Max H. , Fredericq Suzanne 
Published: October 2004

ABSTRACT The Myriogramme group of Kylin was found to contain two distinct clusters of genera that merit recognition at the tribal level. In this paper, we establish the tribe Myriogrammae based on a study of the type species of Myriogramme, M. livida, from the Southern Hemisphere. The Myriogrammae is characterized by 1) marginal and diffuse intercalary meristems; 2) nuclei arranged in a ring bordering the side walls of vegetative cells; 3) microscopic veins absent; 4) procarps scattered, formed opposite one another on both sides of the blade posterior to one or more vegetative pericentral cells (cover cells) and consisting of a carpogonial branch, a one‐/to two‐celled lateral sterile group and a one‐celled basal sterile group; 5) auxiliary cell diploidized by a connecting cell cut off posteriolaterally from the fertilized carpogonium; 6) gonimoblast initial cut off distally from the auxiliary cell, generating one distal and one to two lateral gonimoblast filaments that branch in the plane of the expanding cystocarp cavity and later fuse to from an extensive, branched fusion cell; 7) spermatangial and tatrasporangial sori formed inside the margin on both sides of the blade by resumption of meristematic activity; and 8) tetrasporangia produced primarily from the central cells. The Myriogrammae currently includes Myriogramme Kylin, Gonimocolax Kylin, Haraldiophyllum A. Zinova, Hideophyllum A. Zinova, and a possible undescribed genus from Pacific North and South America. Genera are separated based primarily on features of gonimoblast and carposporangial development.
CYANOBACTERIAL DOMINANCE OF POLAR FRESHWATER ECOSYSTEMS: ARE HIGH‐LATITUDE MAT‐FORMERS ADAPTED TO LOW TEMPERATURE?1
Authors: Tang Evonne P. Y. , Tremblay Roxanne , Vincent Wanuick F. 
Published: October 2004

ABSTRACTAlthough it is generally believed that cyanobacteria have high temperature optima for growth (> 20° C), mat‐foming cyanobacteria are dominant in many types of lakes, streams, and ponds in the Arctic and Antarctic. We studied the effect of temperature on growth (μ) and relative pigment composition of 27 isolates of cyanobacteria (mat‐forming Oscillatoriaceae) from the Arctic, subarctic, and Antarctic to investigate whether they are a) adapted to the low temperature (i.e. psychrophilic) or b) tolerant of the low temperature of the polar regions (i.e. psychrotrophic). We also derived a parabolic function that describes both the rise and the decline of cyanobacterial growth rates with increasing temperature. The cyanobacteria were cultured at seven different temperatures (5°‐35° C at 5° C intervals), with continuous illumination of 225 μmol photons.m−2.s−1. The parabolic function fits the μ‐temperature data with 90% confidence for 75% of the isolates. Among the 27 isolates of cyanobacteria studied, the temperature optima (Topt) for growth ranged from 15° to 35° C, with an average of 19.9° C. These results imply that most polar cyanobacteria are psychrotrophs, not psychrophiles. The cyanobacteria grew over a wide temperature range (typically 20° C) but growth rates were low men at Topt (average μmax of 0.23 ± 0.069 d−1). Extremely slow growth rates at low temperature and the high temperature for optimal growth imply that the cyanobacteria are not adapted genetically to cold temperatures, which characterize their ambient environment. Other competitive advantages such as tolerance to desiccation, freeze—thaw cycles, and bright, continuous solar radiation may contribute to their dominance in polar aquatic ecosystems.
OCCURRENCE OF PHYIWATED CHLOROPHYLLcINISOCHRYSIS GALBANAANDISOCHRYSISSP. (CLONE T‐ISO) (PRYMNESIOPHYCEAE)1
Authors: Zapata Manuel , Garrido José L. 
Published: October 2004

ABSTRACTThe pigment composition of two clones ofIsochrysis galbanaParke (CCMP 1323 and CCAP 927/1), andIsochrysissp. (clone T‐ISO) was analyzed by high‐performance liquid chromatography using a polymeric octadecylsilica column. Fluorescent peaks with retention times higher than chlorophyllawere detected for all three clones. The corresponding pigments were isolated and characterized in terms of their visible absorbance and fluorescence spectra. The pigments were similar to phytol‐substituted chlorophyllc,previously isolated from Emiliania huxleyi (Lohm.) Hay and Mohler and other species containing chlmophyll c3. The presence of phytol‐substituted chlorophyllcinI. galbanawhich lacked chlorophyll c3, increases the diversity of chlorophyll patterns for the Haptophyta, which can be grouped, at present, into six different pigment types. This is the jrst observation of a haptophyte containing the apolar phytylated chlorophyll c‐like pigment but lacking chlorophyll c3.
INFLUENCE OF ULTRAVIOLET RADIATION ON GROWTH AND PHOTOSYNTHESIS OF TWO COLD OCEAN DIATOMS1
Authors: Nilawati Jusri , Greenberg Bruce M. , Smith Ralph E. H. 
Published: October 2004

ABSTRACTThe influence of chronic exposure to UV‐B and UV‐A radiation on growth and photosynthesis of two polar marine diatoms (Pseudonitzschia seriata and Nitzschia sp.) was investigated in cultures exposed to moderate photon fluences for 3–7 days. Population growth rates were diminished 50% by UV‐B. Fluorescence induction kinetics of photo‐system II (PSII) revealed that UV‐B caused lower Fv/Fm ratios and half‐rise times, indicating damage to the reaction center of PSII and to related elements of the photosynthetic electron transport chain. Carbon assimilation rates per cell and per chlorophyll a were nonetheless highest for UV‐B—exposed populations, which also had the highest chlorophyll a content per cell. The UV‐B—exposed cells were, however, more vulnerable to visible light‐induced photoinhibition. Exposure to UV‐A in the absence of UV‐B had little effect on growth, fluorescence induction of PSII, or chlorophyll a contents but did have some inhibitory effects on carbon assimilation per chlorophyll a and per cell. The increased photosynthetic capacity of UV‐B‐exposed cells suggested some ability to compensate for damage to the photosynthetic apparatus.
EFFECT OF IRON NUTRITION ON THE MARINE CYANOBACTERIUM SYNECHOCOCCUS GROWN ON DIFFERENT N SOURCES AND IRRADIANCES1
Authors: Kudo Isao , Harrison Paul J 
Published: October 2004

ABSTRACTThe effects of Fe deficiency on the marine cyanobacterium Synechococcus sp. were examined in batch cultures grown on nitrate or ammonium as a sole nitrogen source under two different irradiances. Fe‐stressed cells showed lower chlorophyll a content and cellular C and N quotas. Light limitation increased the critical iron concentration below which both suppression of growth rate and changes in cellular composition were observed. At a limiting irradiance (26 μmol.m−2.s−1), this critical value was ∼10 nM, a 10 times increase compared to high‐light cultures. Moreover, at low light the cellular chlorophyll a concentration was higher than at saturating light (110 μmol.m−2.s−1), this difference being most pronounced under Fe‐stressed conditions. Cells grown on ammonium showed a lower half‐saturation constant for Fe (Ks) compared to cells grown on nitrate, indicating Synechococcus sp. has the ability to grow faster on ammonium than on nitrate in a low Fe environment at high light. Consequently, in high‐nutrient and low‐chlorophyll regions where Fe limits new production, cyanobacteria most likely grow on regenerated ammonium, which requires less energy for assimilation. The Ks for growth on Fe at low light was significantly higher than at high light compared with the cells grown on the same N source, suggesting the cells require more Fe at low light. Therefore, if cells that are already Fe‐limited also become light‐limited, their iron stress level will increase even more. For cyanobacteria this is the first report of a study combining the interactions of Fe limitation, light limitation, and nitrogen source (NO3− vs. NH4+).
THE CYTOSKELETON OF THE NAKED GREEN FLAGELLATESPERMATOZOPSZS SIMILIS(CHLOROPHYTA): ANALYSIS OF ISOLATED BASAL APPARATUSES IN THE PARALLEL CONFIGURATION1,2
Authors: Geimer Stefan , Lechtreck Karl‐Ferdinand , Melkonian Michael 
Published: October 2004

ABSTRACTThe biflagellate green algaSpermatozopsis similisis demonstrated to be a model organism for the biochemical and functional analysis of the basal apparatus. Basal apparatuses were isolated in the presence of 10−6M Ca2+, which induces the reorientation of the basal bodies into the parallel state. Serial thin sectioning of enriched basal apparatuses stained with tannic acid reveals several novel details of the structure of the basal bodies, the distal connecting fiber, and the striated microtubule‐associated fibers. We observed a pronounced difference in size of a striated fiber connecting the basal bodies to the five‐stranded microtubular roots depending on its association with the developmentally older or younger basal body. Instead of a proximal connecting fiber, the proximal end of each basal body is associated with a striated triangular plate; these plates appear to serve as spacers for the basal bodies in the parallel and antiparallel configurations. We suggest that the plates play a role in maintaining basal body orientation during forward and backward swimming. The results are summarized in representative drawings of the basal apparatus.
COORDINATNE NUCLEAR AND CHLOROPLAST DIVISION IN UNILOCULAR SPORANGIA OF LAMINARIA ANGUSTATA (LAMINARIALES, PHAEOPHYCEAE)1
Authors: Motomura Taizo , Ichimura Terunobu , Melkonian Michael 
Published: October 2004

ARSTRACTChanges in the number of nuclei and chloroplasts were examined during the process of unispore formation in unilocular sporangia of Laminaria angustata. Just before meiosis, eight chloroplasts were always present in unilocular sporangial mother cells. The number of chloroplasts remained constant through meiosis. After the resulting four nuclei divided again (third nuclear division), a close association between a nucleus and a chloroplast developed among each of the eight nuclei and eight chloroplasts. The eight chloroplasts divided ahost synchronously before the synchronous division of the eight nuclei. Following the 16 nucleate stage with 16 chloroplasts and the final 32 nucleate stage with 32 chloroplasts, 32 unispores, each with a nucleus and a chloroplast, were fomd in unilocular sporangza of L. angustata. Immunofluorescence microscopy using an anti‐centrin antibody showed that two anticentrin‐stained structures (as future mitotic poles) occurred adjacent to each of the premitotic four nuclei, and each spot was located near a chloroplast. Therefore, after the third division, each of the eight nuclei established close contact with a chloroplast presumably mediated by the centrosomes.
PHYLOGENETIC ANALYSIS OFYAMAGISHLELLAANDPLATYDORINA(VOLVOCACEAE, CHLOROPHYTA) BASED ON rbcLGENE SEQUENCES1
Authors: Nozaki Hisayoshi , Ito Motomi , Sano Ryosuke , Uchida Hidenobu , Watanabe Makoto M. , Takahashi Hidenori , Kuroiwa Tsuneyoshi 
Published: October 2004

ABSTRACTYamagishiella, based onPandorina unicoccaRayburn et Starr, is distinguished fromEudorinaby its isogamous sexual reproduction, whereasPlatydorinaexhibits anisogamous sexual reproduction. In the present study, we sequenced the large subunit of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (rbcL) genes from five Japanese and North American strains of Y. unicocca (Rayburn et Starr) Nozaki, twoPlatydorina caudataKofoid strains, and two strains ofEudorina unicoccaG. M. Smith, as well as eight related colonial and unicellular species. Phylogenetic trees were constructed based on these sequence data and on previously published rbcL gene sequences from 23 volvocalean species in order to deduce phylogenetic relationships within the colonial Volvocales, with particular regard to the phylogenetic positions and status of the generaYamagishiellaandPlatydorina.Two robust monophyletic groups of the anisogamous/oogamous volvocacean species were resolved in the maximum‐parsimony tree as well as in the neighbor‐joining distance tree. One of the two groups comprises three species ofVolvoxsectionVolvox,whereas the other is composed of other sections ofVolvoxas well as of all the species ofEudorinaandPleodorina. Platydorina,however, was positioned outside these two monopliyletic groups. Therefore, derivation of thePlatydorinalineage may be earlier than that of such anisogamous/oogamous groups, or orgin of “anisogamy with sperm packets” inPlatydorinamay be independent of sperm packet evolution inEudorina, Pleodorina,andVolvox.It was also resolved with high bootstrap values that all of theY. unicoccastrains form a monophyletic group positioned outside the large monophyletic group includingEudorinaandPleodorina.These reject the possibility of the reverse evolution of isogamy from anisogamy to give rise toYamagishiellawithin the lineage of Eudorina.
DIVERSITY AND PHYLOGENETIC PLACEMENT OF BRACTEACOCCUS TEREG (CHLOROPHYCEAE, CHLOROPHYTA) BASED ON 18S RIBOSOMAL RNA GENE SEQUENCE DATA1
Authors: Lewis Louise A. 
Published: October 2004

ABSTRACTSequence data from the nuclear small‐subunit ribosomal RNA gene was obtained for nine strains of Bracteacoccus Tereg, representing at least five morphological species and four distinct geographic locations. These, along with sequence data from two additional chlorophycean taxa, Spongiochloris spongiosa Starr and Ascochloris multinucleata Bold et MacEntee, and 48 published sequences from green algal taxa, were used to determine the phylogenetic placement of Bracteacoccus with respect to other chlorophycean green algae. Results support the monophyly of Bracteacoccus strains, contrasting with patterns observed so far for many other coccoid green algae. The range of variation among Bracteacoccus strains is similar to that of other congeners. Basal body orientation in Bracteacoccus has been interpreted as clockwise; however, the 18S data point to a relationship between Bracteacoccus and taxa with the directly opposed configuration of the flagellar apparatus. No close relationship was found to the multinucleated green coccoids with clockwise orientation of basal bodies, such as Spongiochloris, or to those with parallel basal bodies, such as Spermatozopsis. However, 18S data confirm that the motile and vegetative cells of Bracteacoccus are structurally distinct from the representatives of sphaeroplealean families currently studied. It is premature to reclassify Bracteacoccus until 18S comparisons can be made with additional sphaeroplealean taxa and with algae with similar flagellar structure such as Dictyochloris and Heterochlamydomonas.
PHYLOGENYAND HISTORICAL ECOLOGY OF THE DESMARESTIACEAE (PHAEOPHYCEAE) SUPPORT A SOUTHERN HEMISPHERE ORIGIN1
Authors: Peters Akira F. , van Oppen Madeleine J. H. , Wiencke Christian , Stam Wytze T. , Olsen Jeanine L. 
Published: October 2004

ABSTRACTPhylogenetic relationships in the Desmarestiales (Phaeophyceae) were inferred among the monotypic Arthrocladia (Arthrocladiaceae) and 27 isolates from Desmarestiaceae, representing 17 taxa of Desmarestia and the monotypic Antarctic genera Himantothallus and Phaeurus. Phaeurus and Arthrocladia were used as outgroups. Parsimony analyses of nuclear ribosomal DNA internal transcribed spacer (ITS1 and ITS2) sequences, in which gaps were both included and excluded, yielded well‐resolved trees with a consistent general branching pattern. A parallel analysis of nine morphological and life‐history characters and three ecological characters yielded a similar tree but provided little resolution in the terminal clades. The position of the monotypic Arthrocladia villosa within the Desmarestiales is consistent with monophyly for the order, but its position as the most primitive desmarestialean is not resolvable from the molecular data set. The basal position of Phaeurus, the Antarctic Desmarestia species, and Himantothallus is consistent with the hypothesis of a Southern Hemisphere origin for the family Desmarestiaceae. The more recent Northern Hemisphere “aculeata” clade evolved from an Antarctic ancestor. A “D. aculeata‐like” species was ancestral to a lineage characterized by annual sporophytes with high sulfuric acid content, which radiated into many species, widely distributed in both hemispheres. Mapping of morphological and ecological characters onto the molecular tree confirm the informativeness of sulfuric acid‐containing vacuoles and unilocular sporangial types. There is good congruence between phylogenetic tree topology and temperature impints in relation to biogeographic distribution, supporting the theory that temperature tolerance is a conservative trait.
PHYLOGENETIC AFFINITIES OF THE SARCINOCHRYSIDALES AND CHRYSOMERIDALES (HETEROKONTA) BASED ON ANALYSES OF MOLECULAR AND COMBINED DATA1
Authors: Saunders Gary W. , Potter Daniel , Andersen Robert A. 
Published: October 2004

ABSTRACTSmall‐subunit ribosomal RNA nucleotide sequences were inferred for Giraudyopsis stellifera Dangeard (Chrysomeridales), as well as for Pulvinaria sp. and Sarcinochrysis marina Geitler (Sarcinochrysidales,). Phylogenetic analyses of the molecular data indicate that the former is weakly related to the Phaeophyceae/Xanthophyceae clade, whereas the latter two have affinities to the Pelagophyceae, and the Sarcinochrysidales sensu stricto is transferred to this class. A recent study proposed that the Pelagophyceae belongs to a larger assemblage of chromophytic species characterized by reduced flagellar apparatuses. Although the flagellar apparatus characterizing the Sarcinochrysidales is reduced relative to the Chysomeridaels and some other chromophytes, it is the most complicated to be associated with “the reduced flagellar apparatus” lineage. Cladistic analyses of a traditional data set (largely ultrastructural features of the flagellar apparatus) and a combined traditional/molecular data set were used to assess the evolutionary trends of reduction in the flagellar apparatus within the heterokont chromophytes.
SEASONAL PATTERNS OF PHOTOSYNTHESIS AND LIGHT‐INDEPENDENT CARBON FIXATION IN MARINE MACROPHYTES1
Authors: Cabello‐Pasini Alejandro , Alberte Randall S. 
Published: October 2004

ABSTRACTThe contribution of light‐independent carbon fixation (LICF) to the overall carbon gain and the seasonal patterns of maximum photosynthesis (Pmax and LICF were characterized in a broad taxonomic range of macrophytes from Monterey Bay, California. Pmax and LICF rates (nmol C.g filtered seawater−1.min−1) varied among species and taxonomic groups examined, and as a function of tissue type in the phaeophyte Laminaria setchellii Silva (Phaeophyceae). On average, Pmax values were higher in the Rhodophyta, whereas LICF rates were greater in the Phaeophyceae. LICF rates were generally less than 5% of Pmax in the marine macrophytes studied and, as a consequence, cannot fully compensate for respiratory carbon losses, which usually are greater than 10% of Pmax. All species studied possessed the highest Pmax and LICF rates when irradiance levels were highest and decreased during periods of low incident irradiance. Seasonal patterns of Pmax and LICF in most of the macrophytes from the stenothermal environment of Monterey Bay were strongly correlated with photosynthetic photon flux rather than seawater temperature. The concomitant decrease of LICF and Pmax rates in all species examined argues against LICF playing a major role in carbon acquisition under light‐limiting conditions as suggested previously. Rather, the strong positive correlation of Pmax and LICF indicates the direct coupling of photosynthate (e.g. 3‐phosphoglyceric acid) generation with production of substrates for LICF reactions. Our results also suggest that LICF might be a useful indicator of photosynthetic metabolism in marine macrophytes.