bluuebunny/crossref_metadata_2025_split huggingface dataset:
COMPARATIVE DEVELOPMENT OF THE RED ALGAL PARASITES BOSTRYCHIOCOLAX AUSTRALIS GEN. ET SP. NOV. AND DAWSONIOCOLAX BOSTRYCHIAE (CHOREOCOLACACEAE, RHODOPHYTA)1
Authors: Zuccarello Giuseppe C. , West John A. 
Published: October 2004

ABSTRACTThe development of two red algal parasites was examined in laboratory culture. The red algal parasite Bostrychiocolax australis gen. et sp. nov., from Australia, originally misidentified as Dawsoniocolax bostrychiae (Joly et Yamaguishi‐Tomita) Joly et Yamaguishi‐Tomita, completes its life history in 6 weeks on its host Bostrychia radicans (Montagne) Montagne. Initially the spores divide to form a small lenticular cell, and then a germ tube grows from the opposite pole. Upon contact with the host cuticle, the germ tube penetrates the host cell wall. The tip of the germ tube expands, and the spore cytoplasm moves into this expanded tip. The expanded germ tube tip becomes the first endophytic cell from which a parasite cell is cut off that fuses with a host tier cell. The nuclei of this infected host cell enlarge. As parasite development continues, other host‐parasite cell fusions are formed, transferring more parasite nuclei into host cells. The erumpent colorless multicellular parasite develops externally on the host, and reproductive structures are visible within 2 weeks. Tetrasporangia are superficial and cruciately or tetra‐hedrally divided. Spermatia are formed in clusters. The carpogonial branches are four‐celled, and the carpogonium fuses directly with the auxiliary (support) cell. The mature carposporophyte has a large central fusion cell and sympodially branched gonimoblast filaments.Early stages of development differ markedly in Dawsoniocolax bostrychiae from Brazil. Upon contact with the host, the spore undergoes a nearly equal division, and a germ tube elongates from the more basal of the two spore cells, penetrates the host cell wall, and fuses with a host tier cell. Subsequent development involves enlargement of the original spore body and division to form a multicellular cushion, from which descending rhizoidal filaments form that fuse with underlying host cells. This radically different development is in marked contrast to the final reproductive morphology, which is similar to B. australis and has lead to taxonomic confusion between these two entities. The different spore germination patterns and early germ‐ling development of B. australis and D. bostrychiae warrant the formation of a new genus for the Australian parasite.
CARBON UPTAKE IN A MARINE DIATOM DURING ACUTE EXPOSURE TO ULTRAVIOLET B RADIATION: RELATIVE IMPORTANCE OF DAMAGE AND REPAIR1
Authors: Lesser Michael P. , Cullen John J. , Neale Patrick J. 
Published: October 2004

ABSTRACTExperiments on a marine diatom, Thalassiosira pseudonana (Hustedt) clone 3H, demonstrate that under moderate photon flux densities (75 μmol quanta·m−2·s−1) of visible light the inhibition of photosynthesis by supplemental ultraviolet (UV) radiation (UV‐B: 280–320 nm) is well described as a hyperbolic function of UV‐B irradiance for time scales of 0.5–4 h. Results are consistent with predictions of a recently developed model of photosynthesis under the influence of UV and visible irradiance. Although net destruction of chlorophyll occurs during a 4‐h exposure to UV‐B, and the effect is a function of exposure, the principal effect of UV‐B is a decrease in chlorophyll‐specific photosynthetic rate. The dependence of photoinhibition on dosage rate, rather than cumulative dose, and the hyperbolic shape of the relationship are consistent with net photoinhibition being an equilibrium between damage and repair. The ratio of damage to repair is estimated by a mathematical analysis of the inhibition of photosynthesis during exposures to UV‐B. A nitrate‐limited culture was much more sensitive to UV‐B than were the nutrient‐replete cultures, but the kinetics of photoinhibition were similar. The analysis suggests that the nutrient‐limited culture was more sensitive than the nutrient‐replete cultures because repair or turnover of critical proteins associated with photosynthesis is inhibited. An inhibitor of chloroplast protein synthesis was used to suppress repair processes. Photoinhibition by UV‐B was enhanced, and inhibition was a function of cumulative dose, as would be expected if damage were not countered by repair. The fundamental importance of repair processes should be considered in the design of field experiments and models of UV‐B effects in the environment, especially in the context of vertical mixing. Repair processes must also be considered whenever biological weighting functions are developed.
ROLE OF RECRUITMENT IN STRUCTURING BEDS OFSARGASSUMSPP. (PHAEOPHYTA) AT ROTTNEST ISLAND, WESTERN AUSTRALIA1
Authors: Kendrick Gary A. , Walker Diana I. 
Published: October 2004

ABSTRACTThe importance of annual recruitment to the structure of adult stands ofSargassumwas determined for a mixed speciesSargassumbed at Rottnest Island, Western Australia. The morphologically similar speciesSargassum spinuligerumSonder,S. distichumSonder, andS. podacanthumSonder grew together in the shallow subtidal (6 m). Positive species determinations were only possible when thalli were reproductive, so recruits, bases, and vegetative annuals for all species were grouped together. Densities of recruits, perennial bases, vegetative annuals, and reproductive annuals were determined at monthly intervals from 20 randomly placed 0.25‐m−2quadrats. Recruitment and mortality for recruits and adults were further determined at three monthly intervals from6‐×‐1‐m−2permanent quadrats.The density of adults varied little with season (between 32 and 58 m−2). Growth of annuals was initiated in April, thalli became reproductive by late August–early September, and senescence occurred in December–January. Density of recruits was highly variable (1.6–210 individuals‐m−2) and peaked seasonally during late summer (January–February) and then declined rapidly.Adults showed a complete turnover of thalli in the bed over 25–27 months. Adult mortality was compensated by annual recruitment from propagules (43%) and vegetative regeneration from fragments of holdfasts left on the reef (57%). A seasonal pattern in survivorship was observed for adults that grew from recruits with higher initial numbers and lower mortalities for August and November cohorts. Little seasonally was observed in survivorship of adults that grew vegetatively from remnant crusts. Although initial cohort sizes were smaller for adults grown from recruits than from remnant crusts, mortality was lower, resulting in similar contributions to adult density from both recruits and remnant crusts.Recruitment from propagules and vegetative regeneration played an important role in buffering the adult stand from high rates of mortality and reducing seasonal variation in adult density and contributed to the persistence and seasonal structure ofSargassumbeds at Rottnest Island.
DIATOM ASSEMBLAGES OF STREAMS INFLUENCED BY WILDFIRE1
Authors: Robinson Christopher T. , Rushforth Samuel R. , Minshall G. Wayne 
Published: October 2004

ABSTRACTThe Greater Yellowstone Area ecosystem experienced major wildfires in 1988, resulting in a substantial number of catchments being burned. We studied diatom assemblage structure at 14 sites over 5 years in catchments ranging from 0 to over 90% burned. Coefficients of variation for selected physical measures provided a good assessment of the degree of disturbance experienced by the various sites and correlated highly with percentage of catchment burned. Principal components analysis quantitatively estimated the degree of temporal change in diatom assemblages at a site. The more extensively burned catchments showed the greatest amount of structural change in diatom taxa among years. Navicula permitis Hust. and Nitzschia inconspicua Grun. were predominant in the heavily disturbed systems, whereas Achnanthes minutissima Kuetz., A. lanceolata (Breb.) Grun., Rhoicosphenia curvata (Kuetz.) Grun. ex Rabh., and Diatoma hiemale var. mesodon (Ehr.) Grun. were common in less disturbed streams. The results demonstrate that recovery trajectories of lotic diatom assemblages following major landscape‐scale disturbances are a function of disturbance intensity resulting from differences in catchment characteristics.
OCCURRENCE OF PRASIOLA FLUVIATILIS (CHLOROPHYTA) ON ELLESMERE ISLAND IN THE CANADIAN ARCTIC1
Authors: Hamilton Paul B. , Edlund Sylvia A. 
Published: October 2004

ABSTRACTThree occurrences of the macroalga Prasiola fluviatilis (Sommerf.) Aresch. were recorded after the examination of 32 stream segments from the Ellesmere Island National Park Reserve (81°23′ N) in the High Arctic of Canada. The collection sites were small (second‐third order) glacial melt streams characterized by pH 7.3–8.2, specific conductance of 52–159 μS·cm−1, low ion levels, extremely low nutrient levels, and the lack of other prominent macroalgae. These occurrences confirm the reported circumpolar distribution of the species.
CELL AND GROWTH CHARACTERISTICS OF TYPES A AND B OF EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE) AS DETERMINED BY FLOW CYTOMETRY AND CHEMICAL ANALYSES1
Authors: van Bleijswijk Judith D. L. , Kempers Rob S. , Veldhuis Marcel J. , Westbroek Peter 
Published: October 2004

ABSTRACTTwo morphotypes of Emiliania huxleyi (Lohmann 1902) Hay et al. 1967, types A and B, known to be unequally distributed in the oceans, were grown in dilution cultures at a range of photon flux densities (PFDs) (1.5–155 μmol photons·m−2·s−1) and two temperatures (10° and 15° C). Calcite carbon and organic carbon content of the cells as well as instantaneous growth rate, cell size, chlorophyll fluorescence, and light‐scatter properties clearly depended on growth conditions and differed considerably for the two morphotypes. The ratio between calcite carbon and organic carbon production showed an optimum of 0.65 in E. huxleyi type A cells at PFD = 17.5. The ratio increased slightly with a temperature increase from 10° to 15°C but remained < 1.0 at both temperatures in light‐limited cells. In contrast, calcite carbon production exceeded organic carbon production (ratio: 1.4–2.2) in phosphate‐deprived cultures. Emiliania huxleyi type B generally showed a higher calcite carbon/organic carbon ratio than E. huxleyi type A, but the relation with PFD was similar.The content of calcite carbon and organic carbon as well as the instantaneous growth rate, cell size, chlorophyll fluorescence, and light‐scatter properties showed large diel variations that were closely related to the division cycle. Our results show the importance of mapping the structure of any sampled cell population with respect to the phase in the cell division cycle, as this largely determines the outcome of not only “per cell” measurements but also short time (less than 24 h) flux measurements. For instance, dark production of calcite by E. huxleyi was negatively affected by cell division. Slowly growing (phosphate‐stressed) cultures produced calcite in the light and in the dark. In contrast, rapidly growing cultures at 10°C produced calcite only in the light, whereas in the dark there was a significant loss of calcite due to dissolution.
STRUCTURAL, TRANSCRIPTIONAL, AND PHYLOGENETIC ANALYSES OF THE atpB GENE CLUSTER FROM THE PLASTID OF CRYPTOMONASΨ (CRYPTOPHYCEAE)1
Authors: Douglas Susan E. , Murphy Colleen A. 
Published: October 2004

ABSTRACTGenes encoding the β and ɛ subunits of the H+‐adenosine triphosphatase complex have been identified in the large single‐copy region of the plastid genome from the marine chlorophyll c‐containing alga Cryptomonas Ψ. Sequence analysis shows that the two genes do not overlap as in most land plants but, rather, are separated by a short 11‐bp intergenic region. The genes lack introns and encode polypeptides of 475 and 131 amino acids, respectively. The two genes are co‐transcribed, producing a transcript of approximately 2000 nucleotides. Primer extension analysis of the 5′ end of the transcript indicates two termini, one more prominent than the other. Sequence motifs typical of chloroplast promoters are located at — 10 and — 35 bp from both of these termini. Upstream of the atpBE operon is a gene with similarity to ORF167 of land plant plastids, and downstream is ORF281, which is homologous to a similarly located open reading frame from a brown alga. Phylogenetic analysis of atpB sequences from a variety of eubacteria and plastids shows all plastids arising from a single origin within the cyanobacteria and a clear dichotomy between the green and non‐green lineages, in agreement with trees based on plastid small‐subunit ribosomal RNA sequences.
PRASINOPHYTES FORM INDEPENDENT LINEAGES WITHIN THE CHLOROPHYTA: EVIDENCE FROM RIBOSOMAL RNA SEQUENCE COMPARISONS1
Authors: Steinkötter Jutta , Bhattacharya Debashish , Semmelroth Ingrid , Bibeau Claude , Melkonian Michael 
Published: October 2004

ABSTRACTComplete nuclear‐encoded small‐subunit ribosomal RNA (rRNA) sequences were determined fromNephroselmis olivaceaStein,Pseudoscourfieldia marina(Throndsen) Manton,Scherffelia dubia(Perty) Pascher, andTetraselmis striataButcher (Chlorophyta) to investigate the evolutionary position of these scaly green flagellates. Results of neighbor‐joining and maximum parsimony phylogenetic analyses demonstrate at least two independent prasinophyte lineages defined byN. olivacea/P. marinaandS. dubia/T. striata, which together with the Chlorophyceae, Pleurastrophyceae, and Ulvophyceae form a monophyletic group. Within this assemblage,N. olivaceaandP. marinarepresent an early‐diverging lineage that is evolutionarily distinct from the later‐divergingS. dubia/T. striataclade. The branch point of theS. dubia/T. striataclade precedes the near‐simultaneous radiation of the Chlorophyceae, Ulvophyceae, and Microthamniales. Though interrelationships between these three latter groups of algae are not resolved, the phylogenetic analyses demonstrate that the Prasinophyceae (sensu Moestrup and Throndsen) and the Pleurastrophyceae (sensu Mattox and Stewart) are not monophyletic classes.
NORTHERN AND SOUTHERN HEMISPHERE HYBRIDS OF MACROCYSTIS (PHAEOPHYCEAE)1
Authors: Lewis Raymond J. , Neushul Michael 
Published: October 2004

ABSTRACTAll combinations of individuals of Macrocystis pyrifera (L.) C. Agardh, M. integrifolia Bory, and M. angustifolia Bory hybridized. Gametophyte isolates obtained from 18 individuals were used, including M. pyrifera and M. integrifolia from the extremes of their Northern Hemisphere ranges along the Pacific Coast of North America and M. pyrifera and M. angustifolia from Tasmania, Australia. All combinations of gametophytes produced sporophytes of normal morphology, with the exception of crosses involving three gametophyte isolates. One female (M. integrifolia) and two male (M. pyrifera and M. angustifolia)gametophyte isolates were unable to produce normal sporophytes in combination with gametophytes of the opposite sex. Some cultures of female gametophytes produced abnormally shaped parthenogenetic sporophytes. Gametophytes and sporangia of M. pyrifera had n= 16 chromosomes. The M. integrifolia female gametophyte that was unable to produce normal sporophytes had n = ca. 32 chromosomes. These results show that these species of Macrocystis have not become reproductively isolated. Although these species may be considered conspecific according to the biological species concept, we recommend that they continue to be recognized as separate species based on morphological differences.
ACTIVE GROWTH OF THE OCEANIC DINOFLAGELLATE CERATIUM TERES IN THE CARIBBEAN AND SARGASSO SEAS ESTIMATED BY CELL CYCLE ANALYSIS1
Authors: Chang Jeng , Carpenter Edward J. 
Published: October 2004

ABSTRACTThe growth rate of an oceanic dinoflagellate, Ceratium teres Kofoid, was investigated in the Sargasso and Caribbean Seas from September 1989 to July 1990 using the cell cycle analysis method. Estimated growth rates ranged from 0.29 to 0.58 day−1 and were 1.5–7.2 times higher than generally accepted rates for oceanic dinoflagellates. The higher rates in this report were mainly due to an improvement in techniques that determine the duration of a terminal cell cycle phase in situ. The day‐to‐day variation in growth rates was surprisingly small, but, from long‐term measurements, a weak correlation was found among temperature, daily irradiance, and seasonal growth rate. The calculated species‐specific primary production ranged from 0.5 to 1.8 mg C·m−2·day−1, about 1% of the estimated total production. Ceratium teres may be an important carbon source at the base of the grazing food chain.
QUANTIFICATION OF THE EFFECTS OF SPORELING COALESCENCE ON THE EARLY DEVELOPMENT OF GRACILARIA CHILENSIS (RHODOPHYTA)1
Authors: Muñoz Alejandro A. , Santelices Bernabe 
Published: October 2004

ABSTRACTSporeling coalescence in species of Gracilariales and Gigartinales is predicted to result in larger basal areas of growing disks as well as earlier initiation, increased abundance, and faster growth rates of erect shoots as compared to noncoalescent sporelings. These responses have been interpreted as providing mutual benefits for organisms living in aggregation, counterbalancing disadvantages associated with crowding. Quantitative evaluations of sporelings of Gracilaria chilensis failed to support several of these predictions. Sporelings were grown in the laboratory from a range of single sporelings to coalescent masses of 20 sporelings. Coalescent sporeling masses of G. chilensis exhibited larger basal areas than noncoalescent ones, but because the specific growth rates were inversely related to the original number of carpospores, no significant differences in actual area increments, during most of the experiment, were found among sporelings derived from one, two, or three to five coalescing sporelings. Initiation of erect shoots occurred at a similar time, regardless of their origin, i.e. coalescent or noncoalescent. Abundance of erect shoots was only loosely related to the number of coalescing sporelings. Even though by the end of the experiment (week 18), the total length of the longer erect shoots arising from coalescent sporeling masses was significantly greater than that of shoots arising from noncoalescent sporelings, total length was independent of the original number of coalescing sporelings. Furthermore, specific elongation rates between week 12 and week 18 were significantly greater for noncoalescent sporelings than for coalescent sporeling masses. Quantitative screening of other species seems necessary before generalizations on the ecological advantages of sporeling coalescence in seaweeds can be made.
ECOTYPIC VARIATION IN PHYLLOPHORA PSEUDOCERANOIDES (RHODOPHYTA) ENSURES WINTER REPRODUCTION THROUGHOUT ITS GEOGRAPHIC RANGE1
Authors: Molenaar Frieda J. , Breeman Anneke M. 
Published: October 2004

ABSTRACTResponses to temperature and daylength were determined in laboratory culture for isolates of the red alga Phyllophora pseudoceranoides (Gmelin) Newroth et A.R.A. Taylor from Nova Scotia, Iceland, Roscoff (France), and Helgoland (Germany). All isolates grew from 3° to 25° C and survived from ‐2° or 0° C to 27° C but not 30° C. Reproductive requirements differed between life history phases and isolates. Isolates from Helgoland and Roscoff formed sporangial sori at 3°‐20° C, tetraspores at 3°‐12° C, and procarps at 10°‐20° C, irrespective of daylength. Spermatangia developed at 10°‐23° C but only in long days. As the other European isolates, the isolate from Iceland formed tetrasporangia at 3°‐12° C, but it had an additional requirement for short days. The Nova Scotian isolate formed sori at 10°‐20° C and sporulated at 10°‐18° C. When grown plants were transferred from noninductive to inductive conditions, sori were formed after 4 months and tetraspores developed and were shed (1‐)3 months later. Procarps formed 1(‐3) months after transfer.The phenology of P. pseudoceranoides was studied at Helgoland and Roscoff, where similar seasonal patterns were observed. Plants were perennial, forming new blades from October to June, which degenerated between August and February. In June, reproductive structures (sori, spermatangia, and procarps) started to appear on the new blades. From October to April, mature cystocarps were found. Mature tetrasporangia were observed only in February.The life history of P. pseudoceranoides is regulated by temperature and daylength. Differential effects on the different life history phases all serve to confine the production of spores (both carpospores and tetraspores) to the winter season. Differences in response between isolates from different geographic regions bring about the same effect: spores are shed only in winter.The nature of the geographic boundaries of P. pseudoceranoides is discussed.
PHOSPHORUS UPTAKE KINETICS OF SPIROGYRA FLUVIATILIS (CHAROPHYCEAE) IN FLOWING WATER1,2
Authors: Borchardt Mark A. , Hoffmann James P. , Cook Philip W. 
Published: October 2004

ABSTRACTThe inorganic phosphorus (Pi) uptake kinetics of Spirogyra fluviatilis Hilse were examined as a function of phosphorus cell quota (QP) and flow velocity in a laboratory stream apparatus. Short‐term uptake and the acclimation of the uptake mechanism to flow were measured by the disappearance of Pi pulses in a recirculating flow cell. Short‐term Pi uptake was biphasic. When the alga was P‐deficient, Phase 1 and 2 half‐saturation constants and maximum uptake rates were 11.0 and 47.2 μg P·L−1 and 473 and 803 μg P·g dry wt−1 h−1, respectively. Flowing water altered short‐term uptake when the alga was P‐deficient, but not when it was P‐replete. When QP was less than 0.21%, increases in flow velocity from 3 to 15 cm·s−1 enhanced uptake with maximum uptake for any Pi pulse at 12 and 15 cm·s−1. At 22 and 30 cm·s−1, uptake was reduced by 12% or more relative to the maxima. If, however, the alga was cultivated at 22 and 30 cm·s−1 and short‐term Pi uptake was measured at 12 cm·s−1, uptake was on average 33% greater than when the alga was cultivated at the latter velocity. Apparently, the alga could adjust short‐term uptake to compensate for the suboptimal conditions of the faster velocities.Long‐term Pi uptake and net phosphorus efflux were estimated by a non‐steady state application of the Droop equation. Long‐term uptake of very low Pi concentrations was not reduced by fast flowing water. Instead, uptake increased proportionately with flow velocity. Maximum phosphorus efflux from S. fluviatilis was 3% of cellular P per hour and occurred when QP was greater than 0.2%. At lower QP, the hourly efflux rate was typically less than 1%. Flowing water did not greatly enhance efflux, although when Pi was undetectable, efflux did tend to increase slightly with velocity. The data show that the effects of flowing water on Pi uptake were varied and not always beneficial. If the effects of flowing water on nutrient acquisition by other lotic algae are similarly varied and complex, flow may be an important determinant of nutrient partitioning among benthic algae in streams.