bluuebunny/crossref_metadata_2025 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

The 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

Experiments 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

The 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

The 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

Three 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

Two 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

Genes 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

Complete 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

All 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

The 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

Sporeling 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

Responses 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

The 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.
EFFECTS OF FLOWING WATER ON NITROGEN‐ AND PHOSPHORUS‐LIMITED PHOTOSYNTHESIS AND OPTIMUM N:P RATIOS BY SPIROGYRA FLUVIATILIS (CHAROPHYCEAE)1,2
Authors: Borchardt Mark A.
Published: October 2004

The effects of flowing water on net photosynthesis, dark respiration, specific growth rate, and optimum N:P ratios by Spirogyra fluviatilis Hilse were assessed. The alga was cultivated under nitrogen or phosphorus limitation in laboratory streams at three flow velocities: 3, 12, and 30 cm·s−1. The Droop equation adequately described respiration and photosynthesis (PSnet) as a function of N or P cell quota (QN or Qp). The data show that for N‐ or P‐limited Spirogyra fluviatilis, flowing water is physiologically costly. Generally, flowing water had little effect on respiration rates; however, the proportion of gross photosynthesis devoted to dark respiration did increase with flow velocity. For photosynthesis, the minimum N and P cell quotas increased with velocity, and the theoretical PSnet maxima for N and P both appeared greatest at 12 cm·s−1. The Droop models showed that for any given QN or Qp, PSnet, was reduced by the 30‐cm·s−1 treatment. Consistent with this finding, independent estimates of specific growth rates for P‐limited S. fluviatilis in the laboratory streams were inversely related to flow velocity when ambient PO4−3 was undetectable. However, growth was not diminished at the fastest velocity when PO4−3 was available for uptake. Thus, the increase in cellular phosphorus demand can be offset by flow‐enhanced P uptake when conditions permit; otherwise, growth will be impaired.

The optimum N:P ratios for S. fluviatilis at 3, 12, and 30 cm·s−1 were 50, 58, and 52 by atoms, respectively, when calculated for PSnet= 0. The optimum ratios were inversely related to PSnet and decreased to approximately 20 when PSnet was near maximum. The potential for flowing water to mediate nutrient partitioning among lotic algae by altering growth rates and optimum nutrient ratios is discussed.
METABOLIC ACTIVITY OF MICROORGANISMS IN EVAPORITES1
Authors: Rothschild Lynn J. , Giver Lorraine J. , White Melisa R. , Mancinelli Rocco L.
Published: October 2004

Crystalline salt is generally considered so hostile to most forms of life that it has been used for centuries as a preservative. Here, we present evidence that prokaryotes inhabiting a natural evaporite crust of halite and gypsum are metabolically active while inside the evaporite for at least 10 months.In situmeasurements demonstrated that some of these “endoevaporitic” microorganisms (probably the cyanobacteriumSynechococcusNägeli) fixed carbon and nitrogen. Denitrifecation was not observed. Our results quantified the slow microbial activity that can occur in salt crystals. Implications of this study include the possibility that microorganisms found in ancient evaporite deposits may have been part of an evaporite community.
CELL CYCLE AND ACCUMULATION OF ASTAXANTHIN IN HAEMATOCOCCUS LACUSTRIS (CHLOROPHYTA)1
Authors: Lee Yuan‐Kun , Ding Sun‐Yeun
Published: October 2004

Synchronous release of ellipsoidal biflagellated zoo‐spores from thick‐walled akinetes of Haematococcus lacustris (Gir.) Rostaf. (UTEX 16) was induced. After being released, the zoospores divided rapidly at a rate that depended on the initial concentration of urea in the culture medium. Cells fused after approximately five doublings, and the DNA content of most cells doubled within 50 h. Spherical nonmotile palmella cells and aplanospores appeared after 100 h of incubation in media containing high (1.7 g·L−1) and low (0.85 g·L−1) urea concentrations. Thereafter, the number of nonmotile cells increased with time, whereas motile cell numbers decreased with time. Nonmotile cells continued to grow and divide by forming 4–32 aplanospores, for up to 200 h of incubation in the high‐urea medium. The size of the nonmotile cells and the number of daughter cells formed within was inversely proportional to the growth rate of the cultures. Within the first 100 h of incubation, dry weight biomass of the zoo‐spores increased from about 0.3 to 0.8 g·L−1. In the following 180 h, dry weight biomass reached 1.7 g·L−1 in the low‐urea medium and 2.5 g·L−1 in the high‐urea medium. The astaxanthin content of zoospores decreased with time, whereas there was a net accumulation of astaxanthin in the nonmotile cells. The specific rate of accumulation of astaxanthin in motile and nonmotile cells, however, was practically identical.
DETECTION OF PROLIFERATING CELL NUCLEAR ANTIGEN ANALOG IN FOUR SPECIES OF MARINE PHYTOPLANKTON1
Authors: Lin Senjie , Chang Jeng , Carpenter Edward J.
Published: October 2004

Proliferating cell nuclear antigen (PCNA) is an auxiliary protein for polymerase‐δ and therefore is essential for cellular DNA synthesis. The synthesis and abundance of PCNA in the cell are cell‐cycle‐dependent, both increasing markedly during the S phase. Such a protein could be a useful cell cycle marker, which is required for estimating algal species‐specific growth rates via the cell cycle approach. By using commercially available monoclonal anti‐rat‐PCNA antibody and an enhanced chemiluminescence technique, PCNA‐like proteins were detected in four species of marine phytoplankton. The strong single band detected on western blots of Isochrysis galbana Parke, Thalassiosira weissflogii Cleve, and Dunaliella tertiolecta Butcher had an apparent molecular weight of 33–36 kDa. This molecular weight is within the range as observed for PCNA in a wide phylogenetic array of organisms (33–36 kDa). In the diatom Skeletonema costatum (Grev.) Cleve, the PCNA antibody detected a major band of about 19 kDa as well as a minor band of 38 kDa. The detected proteins were specifically recognized by the monoclonal anti‐rat‐PCNA antibody. The PCNA‐like proteins in I. galbana, T. weissflogii, and D. tertiolecta were more abundant in the exponential growth stage and then decreased and became undetectable in the late stationary stage. Our results show that the detected antigens appear to be algal analogs of PCNA.
SALINITY TOLERANCE, BILIPROTEINS, AND FLORIDOSIDE CONTENT OF COMPSOPOGON COERULEUS (RHODOPHYTA)1
Authors: Glazer Alexander N. , Chan Crystal F. , Karsten Ulf , West John A.
Published: October 2004

The freshwater red alga Compsopogon coeruleus (Balbis) Montague is capable of growing and reproducing in salinities up to 35 ppt. Increased accumulation of floridoside (D‐galactopyranosyl glycerol) parallels increase in salinity. Compsopogon phycobilisomes contain an unusual B‐phycoerythrin completely lacking in phycourobilin chromophores, but with a pigmented γ subunit. The α, β, and γ subunits of this phycoerythrin all carry phycoerythrobilins. These results suggest that C. coeruleus is secondarily adapted to freshwater from marine habitats.
HOST SPECIFICITY IN THE RED ALGAL PARASITES BOSTRYCHIOCOLAX AUSTRALIS AND DAWSONIOCOLAX BOSTRYCHIAE (CHOREOCOLACACEAE, RHODOPHYTA)1
Authors: Zuccarello Giuseppe C. , West John A.
Published: October 2004

The determinants of host specificity, which are poorly understood in red algal parasites, were studied in the red algal parasites Bostrychiocolax australis Zuccarello et West and Dawsoniocolax bostrychiae (Joly et Yamaguishi‐Tomita) Joly et Yamaguishi‐Tomita. Culture studies were performed to determine host range, sites of host resistance, and genetics of transmission of resistance. Both species parasitize Bostrychia radicans (Montagne) Montagne, whereas Bostrychiocolax australis also parasitizes Bostrychia moritziana (Sonder ex Kützing) J. Agardh and Stictosiphonia kelanensis (Grunow ex Post) R. J. King et Puttock. Isolates of B. radicans resistant to both parasites were found worldwide, often within the same population as susceptible isolates. On resistant Bostrychia species and isolates, specificity was manifested at three stages: 1) host penetration, in which the spore germ peg failed to penetrate the host cuticle/wall; 2) parasite–host cell fusion, in which the fusion cell died and the parasite died; and 3) growth, in which parasites grew but soon died; parasites rarely reproduced and infections did not continue in culture. Resistance to parasite infection was usually transmitted as a dominant trait and did not segregate as a single locus during meiosis. In certain crosses, transmission of resistance was non‐mendelian.
18S RIBOSOMAL DNA SEQUENCES INDICATE A MONOPHYLETIC ORIGIN OF CHAROPHYCEAE1
Authors: Ragan Mark A. , Parsons Thomas J. , Sawa Takashi , Straus Neil A.
Published: October 2004

Nuclear‐encoded small‐subunit (18S) ribosomal RNA genes ofChara australisR. Brown(C. corallinavar.nobilisf.nobilisR.D.W.) andNitella flexilis (L.)Ag. were amplified by polymerase chain reaction, cloned, and completely sequenced. Using structural criteria, the sequences were aligned with 18S ribosomal DNAs (rDNAs) from 11 other chlorophyllb‐containing algae and six higher plants (embryophytes). Phylogenetic trees were inferred by distance, neighbor‐joining, parsimony, and maximum‐likelihood approaches; confidence intervals were estimated by bootstrapping, and nonrandomness of tree structure was confirmed by permutation tests. 18S rDNAs ofC. australisand twoNitellaspecies were found to be specifically related and, together with 18S rDNAs ofChlorokybus atmophyticusGeitler,Klebsormidium flaccidum(A. Br.) Silva, Mattox, et Blackwell, and twoColeochaetespecies, support a robust monophyletic group (Charophyceae). Although most trees favored a specific sister‐group relationship between Charophyceae and embryophytes, statistical tests revealed that a sister‐group relationship between Charophyceae and Chlorophyceae could not be ruled out. Additional complete sequences from 18S rDNAs of lower land plants may be required to resolve phylogenetic relationships among these organisms.
ISOLATION AND CHARACTERIZATION OF PHASE‐SPECIFIC COMPLEMENTARY DNAs FROM SPOROPHYTES AND GAMETOPHYTES OF PORPHYRA PURPUREA (RHODOPHYTA) USING SUBTRACTED COMPLEMENTARY DNA LIBRARIES1
Authors: Liu Qing Yan , van der Meer John P. , Reith Michael E.
Published: October 2004

The red alga Porphyra purpurea (Roth) C. Agardh has a life cycle that alternates between shell‐boring, filamentous sporophytes and free‐living, foliose gametophytes. The significant morphological differences between these two phases suggest that many genes should be developmentally regulated and expressed in a phase‐specific manner. In this study, we prepared and screened subtracted complementary DNA (cDNA) libraries specific for the sporophyte and gametophyte of P. purpurea. This involved the construction of cDNA libraries from each phase, followed by the removal of common clones through subtractive hybridization. Sampling of the subtracted libraries indicated that 8–10% of the recombinant colonies in each library were specific for the appropriate phase. Of 20 putative phase‐specific cDNAs selected from each subtracted library, eight unique clones were obtained for the sporophyte and seven for the gametophyte. After confirming their phase‐specificities by hybridization to gametophyte and sporophyte messenger RNA, these 15 phase‐specific cDNAs were sequenced, and the deduced amino acid sequences were used to search protein databanks. Two proteins encoded by the sporophyte‐specific cDNAs and two by the gametophyte‐specific cDNAs were identified by their similarity to databank entries.
MOLECULAR DELINEATION OF SPECIES AND SPECIES RELATIONSHIPS IN THE RED ALGAL AGAROPHYTES GRACILARIOPSIS AND GRACILARIA (GRACILARIALES)1
Authors: Goff Lynda J. , Moon Debra A. , Coleman Annette W.
Published: October 2004

Delineation of species in the economically important agarophyte genera Gracilaria and Gracilariopsis has proven extremely difficult using available morphological characteristics. In this study, we examine the usefulness of two transcribed spacers for molecular systematic studies of these genera. The polymerase chain reaction was used to amplify the internal transcribed spacers (ITSs) and the intervening 5.8S ribosomal DNA of the nuclear ribosomal repeat region. In addition, a plastid spacer region and flanking regions of coding genes were amplified from the RUBISCO operon. Both regions were sequenced for individuals and populations of Gracilariopsis lemaneiformis (Bory) Dawson, Acleto, et Foldvik to determine the usefulness of these spacers in delimiting populations. These studies reveal that there is as much variation among individuals of a population as there is between individuals of geographically separate populations. In addition, the ITS spacer regions were compared between different species of Gracilariopsis and Gracilaria. The nuclear ITS spacer region is conserved at a species level in both genera and provides phylogenetically informative characters that can be used to examine species interrelationships among relatively closely related taxa. However, because of the difficulties of aligning this entire region among species from the two genera, the ITS region is not useful for examining intergenera relationships. ITS interspecies sequence comparisons indicate that Gracilariopsis lemaneiformis from California is significantly different from G. lemaneiformis from China and that a species of Gracilariopsis from Peru is more closely related to G. lemaneiformis from North Carolina than it is to the other Gracilariopsis species examined. In addition, these studies indicate that Gracilaria chilensis Bird, McLachlan, et Oliveira from New Zealand and Gracilaria tenuistipitata Chang et Xia from southeast Asia are as closely related as are Gracilaria verrucosa (Hudson) Papenfuss, G. pacifica Abbott, and Gracilaria robusta Kylin. Phylogenetic analysis of aligned plastid spacer sequences from Gracilaria and Gracilariopsis taxa provide similar conclusions about species relationships.
TETREUTREPTIA POMQUETENSIS GEN. ET SP. NOV. (EUGLENOPHYCEAE): A QUADRIFLAGELLATE, PHOTOTROPHIC MARINE EUGLENOID1
Authors: McLachlan Jack L. , Seguel Miriam R. , Fritz Lawrence
Published: October 2004

A new euglenoid genus and species, Tetreutreptia pomquetensis, is described from winter waters of Maritime Canada. This phototrophic species is characterized by four emergent heterodynamic flagella, two about the length of the cell and two less than one‐half this length. Tetreutreptia pomquetensis has features in common with species of Eutreptiella while it differs in several respects from any of the described species of that genus. It could be assigned to the order Eutreptiales or Euglenamorphales sensu Leedale or the order Euglenales sensu Farmer. This new alga has a narrow range of temperature tolerance; it grows best from 0° to 7° C and dies at temperatures above 10° C. The optimum salinity for growth was near full‐strength seawater. Growth conditions for the alga define the conditions whence this species was isolated.
GENETIC VARIABILITY WITHIN A POPULATION AND BETWEEN DIPLOID/HAPLOID TISSUE OF MACROCYSTIS PYRIFERA (PHAEOPHYCEAE)1
Authors: Coyer James A. , Robertson Deborah L. , Alberte Randall S.
Published: October 2004

Multi‐locus DNA fingerprints using an M13 probe were obtained for eight individuals of giant kelp Macrocystis pyrifera (L.) C. Ag. collected from Monterey Bay, California. For each individual, DNA was extracted from a diploid blade and from ca. 109 haploid spores that were released from four to Jive sporophylls. Viable or swimming spores from one individual were pooled and referred to as a spore group. A total of 34 bands (4–19 kb) was detected in DNA fingerprints from the eight blades and eight spore groups, with individual blade or spore groups exhibiting 7–18 bands (mean = 12.6). One band (4.5 kb) was present in all 16 samples. Eight bands were detected in 11–14 of the 16 samples. Similarity indices were calculated for all pairwise comparisons of fingerprint bands among all possible combinations of blades and spore groups. Mean similarity indices for the eight blades (0.51, SE = 0.032) and spore groups (0.56, SE = 0.031) were significantly lower than for the eight comparisons of the blade and spore groups from a single individual (0.86, SE = 0.052). The data indicate that DNA fingerprints can be used to measure genetic variation within populations of M. pyrifera because variation of DNA fingerprints associated with meiotic products (spores) of a given individual is small relative to variation observed among individuals within the population. Additionally, fingerprint variation between diploid vegetative tissue and haploid meiotic products may be a measure of genetic change due to recombination or DNA turnover mechanisms.
QUANTITATIVE GENETICS OF FATTY ACID VARIATION IN ISOCHRYSIS GALBANA (PRYMNESIOPHYCEAE) AND PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE)1
Authors: Alonso Diego López , del Castillo Clara I. Segura , Sánchez José L. García , Sánchez Pérez José A. , Camacho Francisco Garcia
Published: October 2004

Fatty acid variation among culture collection strains and 40 new isolates of Isochrysis galbana Parke was analyzed by quantitative genetic methods. Fatty acid variation among strains and among isolates was highly significant for major fatty acids showing the existence of a genetic component in the determination of differences in fatty acid content. The heritabilities for the major fatty acids ranged between 0.68 and 0.99 among collection strains and between 0.31 and 0.43 among isolates. Eicosapentaenoic acid (EPA) had the highest heritability in I. galbana, but the majority of remaining fatty acids also showed high heritability values. A similar experiment with five UTEX strains of Phaeodactylum tricornutum also showed the presence of a genetic component in four out of seven major fatty acids. Nevertheless, the UTEX strains did not differ significantly in EPA content, although they showed a heritability of 0.40 for this fatty acid. An additional experiment culturing the same isolates of I. galbana in larger volumes of media showed that there was a high significant positive linear relation between EPA content in different volumes. Therefore, EPA content in small volume cultures was an unbiased indicator of EPA content in larger volume cultures. Our results provide support for the genetic determination of fatty acid content in microalgae and suggest that selection, and mutation and selection, are likely to improve EPA content in I. galbana and probably in many other microalgae. Such a selection program can be carried out in small‐volume cultures with high confidence.
CRYOPRESERVATION OF THE CONCHOCELIS OF PORPHYRA (RHODOPHYTA) BY APPLYING A SIMPLE PREFREEZING SYSTEM1
Authors: Kuwano Kazuyoshi , Aruga Yusho , Saga Naotsune
Published: October 2004

The conchocelis cells of four strains of Porphyra yezoensis Udea and four other Porphyra species were cryopreserved in liquid nitrogen (LN) using a programmable freezer or a simple prefreezing system, which consisted of a styrofoam box and a deep‐freezer at −40° C. The cells differed in their freezing tolerance but survived maximally when prefrozen to −40° C in a cryoprotective solution composed of 10% dimethylsulfoxide and 0.5 M sorbitol in 50% seawater. The cryopreservation was successfully performed by applying the simple prefreezing system as well as by a programmable freezer. Conchocelis cells thawed from the LN temperature formed colonies and retained the ability to form conchospores that grew into gametophytic thalli. This technique using a simple prefreezing system will accelerate the spread of Porphyra cryopreservation.
GROWTH OF THE FILAMENTOUS GREEN ALGA CTENOCLADUS CIRCINNATUS (CHAETOPHORALES, CHLOROPHYCEAE) IN RELATION TO ENVIRONMENTAL SALINITY1
Authors: Herbst David B. , Castenholz Richard W.
Published: October 2004

Clones of the filamentous green alga Ctenocladus circinnatus Borzi were isolated from algae collected at Abert Lake (Oregon) and Mono Lake (California). Stock cultures were exposed to varied salinities of natural lake water to examine the effects on growth rate, cell form, chlorophyll a, and water content. Growth rates were reduced in both clones with increased salinity over the range 25–100 g·L−1 and were almost completely inhibited at 150 g·L−1. Chlorophyll a increased between salinities of 25 and 100 g·L−1, reflecting slower growth, higher proportions of akinetes, and smaller cell sizes as salinity increased. Tissue water content remained essentially constant from 25 to 100 g·L−1 salinity. Shorter cell dimensions with increased salinity suggest that a lower surface‐to‐volume ratio may reduce the potential for passive loss of cell water. Prior acclimation of stock cultures to elevated salinity provided no enhancement of growth response at any salinity. The results indicate that environmental salinity can limit the productivity and distribution of Ctenocladus in nature.
RADIOLABELING STUDIES OF LIPIDS AND FATTY ACIDS IN NANNOCHLOROPSIS (EUSTIGMATOPHYCEAE), AN OLEAGINOUS MARINE ALGA1
Authors: Schneider Jane C. , Roessler Paul
Published: October 2004

The synthesis of fatty acids and lipids in Nannochloropsis sp. was investigated by labeling cells in vivo with [14C]‐bicarbonate or [14C]‐acetate. [14C]‐bicarbonate was incorporated to the greatest extent into 16:0, 16:1, and 14:0 fatty acids, which are the predominant fatty acids of triacylglycerols. However, more than half of the [14C]‐acetate was incorporated into longer and more desaturated fatty acids, which are constituents of membrane lipids. [14C]‐acetate was incorporated most strongly into phosphatidylcholine, which rapidly lost label during a 5‐h chase period. The label associated with phosphatidylethanolamine also decreased during the chase period, whereas label in other membrane lipids and triacylglycerol increased. The dynamics of labeling, along with information regarding the acyl compositions of various lipids, suggests that 1) the primary products of chloroplast fatty acid synthesis are 14:0, 16:0, and 16:1; 2) C20 fatty acids are formed by an elongation reaction that can utilize externally supplied acetate; 3) phosphatidylcholine is a site for desaturation of C18 fatty acids; and 4) phosphatidylethanolamine may be a site for desaturation of C20 fatty acids.
KINETICS OF BLUE‐LIGHT STIMULATION AND CIRCADIAN RHYTHMICITY OF LIGHT‐SATURATED PHOTOSYNTHESIS IN BROWN ALGAE: A SPECIES COMPARISON1
Authors: Schmid Rainer , Dring Matthew J. , Forster Rodney M.
Published: October 2004

The time courses of photosynthetic rates in red light, with and without additional blue light, were investigated and compared in 20 species of brown algae. Species could be separated into two groups on the basis of the rhythmicity of their photosynthesis in red light and the kinetics of their responses to blue‐light pulses. One group, which consisted of members of the Ectocarpales, Chordariales, and Dictyosiphonales, was characterized by strong and persistent circadian rhythmicity in red light. The photosynthetic responses of these species to blue‐light pulses started within 10–30 s of the beginning of blue‐light treatment and mostly contained at least two distinct kinetic components. An early component, which reached a maximum about 5–10 min after the blue‐light pulse, was always detectable. Later components were seen as separate peaks or shoulders after an additional 10–20 min. The decay of the response in this group of species was mostly slow, with half‐lives of between 0.5 and 1.5 h. In the second group of species, consisting of members of the Dictyotales, Laminariales, and Fucales, photosynthesis in red light was usually non‐rhythmic, although circadian rhythms with a weak amplitude or of transient occurrence were observed in some plants of some species. The increase in photosynthesis in response to a blue‐light pulse was not detectable until 70–330 s after the start of blue‐light treatment, and the response itself had only a single component, with a maximum after about 10 min and half‐life of 10–20 min. The lengths of the lag‐phases were positively correlated with the times taken to reach the peak in this group, although the lag‐phases and the half lives sometimes varied with time in individual plants. Two members of the Sphacelariales (Sphacelaria, Cladostephus) did not fit into either of the two groups because their photosynthesis was rhythmic, but their responses had long lag‐phases, a single component, and moderately long half‐lives. The differences in the kinetics of the photosynthetic response to blue‐light pulses, which have been described for the two main groups of species, are thought to indicate that there are two distinct mechanisms by which light‐saturated photosynthesis responds to blue light in brown algae. Since in some species the maximal photosynthesis after a blue‐light pulse and the rate of photosynthesis in continuous blue light also varied in a circadian pattern, the response to blue light itself may be under circadian control.