bluuebunny/crossref_metadata_2025 huggingface dataset:
CELL CYCLE REGULATORS IN THE FLORIDA RED TIDE DINOFLAGELLATE, GYMNODINIUM BREVE
Authors: Barbier M. , Leighfield T.A. , Van Dolah F. M.
Published: March 2003

The diel cycle is a key regulator of the cell cycle in many dinoflagellates, and may play a rate limiting role in bloom formation. Diel phasing of the cell cycle in the Florida red tide dinoflagellate, Gymnodinium breve Davis was previously described in our laboratory. In cultures grown on a 16:8 light:dark cycle, S‐phase began 6–8 h into the light phase, and mitosis followed 12–14 h later. The dark/light “dawn” transition was found to provide the diel cue that serves to entrain the G. breve cell cycle. However the cell cycle mechanisms and regulators acted upon by this cue are poorly understood in dinoflagellates. The cell cycle regulatory complex, CDK1‐cyclinB, is therefore currently being investigated. Cyclin dependent kinase (CDK) was first identified in G. breve using two approaches: (1) identification of a 34 kDa protein immunoreactive to an antibody raised against a conserved amino acid sequence unique to the CDK protein family (PSTAIR) and (2) inhibition of the cell cycle by olomoucine, a selective CDK inhibitor. Several approaches are currently being employed in order to describe its partner, cyclin B: (1) PCR on genomic DNA with primers deduced from known cyclin box sequences, (2) G. breve expression library screening with an antibody raised against the fission yeast cyclin B (3) western blot analysis on whole protein extracts and cyclin B immunoprecipitated proteins. Current work focuses on the differential expression of the cyclin B homologue in G. breve during its cell cycle and its relation to diel cycle control.
SYSTEMATICS AND PHYLOGEOGRAPHY OF THE INVASIVE RED ALGA, POLYSIPHONIA HARVEYI
Authors: McIvor L.M. , Maggs C.A. , Stanhope M.J.
Published: March 2003

Polysiphonia harveyi Bailey was first described from Connecticut in 1848 and morphologically similar species, such as P. japonica and P. strictissima, have subsequently been described many times from different localities such as Japan and New Zealand, placing the taxonomy and nomenclature of this morphologically variable species in confusion. Polysiphonia harveyi is regarded as an alien in the British Isles and the north‐eastern North Atlantic and is reported to be spreading rapidly. The first confirmed collection of P. harveyi from the British Isles was in 1908; the source of the British introduction remains unknown. In conjunction with breeding data, rbcL sequences for samples of P. harveyi, P. strictissima, P. japonica and P. akkeshiensis collected from New Zealand, Atlantic and Pacific North America, Japan and Europe, reveal that P. harveyi, P. japonica and P. akkeshiensis constitute a single biological species. The correct name for this is P. harveyi, whilst P. strictissima from New Zealand is a sibling species, distinct from P. harveyi. The center of genetic diversity of P. harveyi is in Japan. The original source of the introduced P. harveyi in the British Isles, Europe and Nova Scotia appears to be Hokkaido, Japan. Separate introductions from a single source population into New Zealand and Pacific and Atlantic North America from Honshu, Japan, apparently have occurred.
RELATING PHYTOPLANKTON BIOMASS AND PRODUCTION TO EPISODIC PHYSICAL FORCING IN SOUTHEASTERN LAKE MICHIGAN
Authors: Millie D.F. , Fahnenstiel G. L. , Lohrenz S.E. , Schofield O.
Published: March 2003

Spatial and temporal dynamics in phytoplankton reflect of the combined effects of the physical and chemical environments and associated biological responses. Although alterations in phytoplankton are well‐documented for a variety of lentic waters, the exact linkages between environmental forcing and phytoplankton assemblages remain poorly understood (particularly for coastal systems). A recurrent sediment resuspension event occurs every late winter/early spring in southeastern Lake Michigan, often extending greater than ten km in width and 300 km in length. Inherently, such a large‐scale and dramatic physical process would be thought to dramatically influence phytoplankton assemblages; however, linkages between the turbidity plume and phytoplankton assemblages have been postulated, but never verified. As such, the episodic nature of the plume provided an opportunity to examine the effects of a short‐term physical forcing event on coastal phytoplankton in relation to more persistent, seasonal meteorological forcing. Lake phytoplankton assemblages within and outside of the RCP were examined during the spring isothermal period from 1998 to 2000. Here, we describe results from the 1998 and 1999 field seasons characterizing the distribution of phytoplankton biomass and composition within and adjacent to the RCP and their relationship to particulate and dissolved constituents. In addition, the spatial and temporal patterns in production and photosynthetic characteristics of the phytoplankton community are examined.
SEPARATING POPULATION STRUCTURE FROM POPULATION HISTORY IN ASCOPHYLLUM NODOSUM (FUCALES)
Authors: Olsen J. L. , Stam W.T.
Published: March 2003

Ascophyllum nodosum is dominant seaweed along many rocky intertidal shores throughout the North Atlantic. Next to the kelps, fucalean taxa such as Ascophyllum are the largest macrophytes and provide important habitat for invertebrates. Understanding the underlying genetic structure of natural populations over a range of spatial scales can reveal how the causes of structure may change with scales. Separating population history from population structure may also be elucidated. The analysis is based on six polymorphic microsatellite loci and> 1000 individuals. Strong genetic structure at small spatial scale was found and is consistent with demographic models based on long‐lived individuals, low recruitment and many sib matings. At large spatial scales only weak population differentiation was found. This is consistent with recent recolonization of the North Atlantic following the last glacial maximum.
ARE SPERM LIMITING IN THE SEA?
Authors: Berndt M. L. , Brawley S.H.
Published: March 2003

The reproductive success of marine species with external fertilization depends on environmental conditions during gamete release. There is special interest presently in whether water motion causes sperm limitation under natural conditions. We investigated gamete release of Fucus vesiculosus from an exposed shore to ascertain: 1) when gametes are released during the tidal cycle, 2) when fertilization occurs, and 3) what the natural sperm:egg ratios are. Water samples were collected and concentrated over five minutes every half hour off Pemaquid Point, ME from three replicate sites within each of two locations using a pump‐filter device. Immunofluorescence microscopy revealed that gamete release occurred only on the two calmest spring tides. Sperm became present in the water column at the same time as oogonia (30 min−1 h prior to high tide [HT]) and reached peak concentration at exactly HT. The sperm:egg ratio was 76:1 on 8 Oct 1999 and 21:1 on 8 Nov 1999 at exactly 30 min prior to HT and dropped sharply after HT. Gametes continued to be collected for several hours after HT but analysis of pronuclear position in aceto‐iron‐hematoxylin stained eggs revealed that all fertilization occurred at approximately HT. We modelled the total number of days when reproduction was possible using these results and wind and wave data from the National Data Buoy Center. Our research provides evidence that gamete release by F. vesiculosus occurs at slack HT on calm days and that sperm are not a limiting factor in fertilization for this species.
TAXONOMY OF THE LENORMANDIA ‐ LENORMANDIOPSIS COMPLEX (RHODOMELACEAE, RHODOPHYTA)
Authors: Phillips L.E. , Nelson W.A. , Kraft G.T.
Published: March 2003

The genus Lenormandia is composed of nine species from Australia and New Zealand. Some of the these are well known, but others are rare, obscure and ill‐defined. We have examined material of all described species and found that they fall into two discrete groups that differ in apex morphology and position of reproductive structures. Plants of the first group, containing the type species L. spectabilis, have a cleft apex and reproductive structures produced directly on the blade surface, whereas those of the second group have a strongly inrolled apex and produce reproductive structures dorsally on small branchlets which arise either from the margins or the midrib. The groups were also found to form discrete clades on analysis of 18S rRNA sequences. All the members of the first group are endemic to Australia, whereas the second group, designated by the new genus name Adamsiella, contains two previously described New Zealand species and a single Australian representative. In addition, two new species are described in this group from New Zealand. Members of the closely related genus Lenormandiopsis were also examined and the type species, L. latifolia, was found to conform in apex morphology and position of reproductive structures to the genus Lenormandia. Accordingly Lenormandiopsis has been subsumed within Lenormandia. The remaining three members of the former genus Lenormandiopsis, however, were found to differ from both the type species and the genus Lenormandia and consequently have been transferred to the separate genus Geraldia, along with a new species from Geraldton, Western Australia which is designated as the type.
CALCIUM OXALATE CRYSTALS IN THE GREEN ALGA SPIROGYRA SP. (ZYGNEMATALES, CHLOROPHYTA)
Authors: Pueschel C. M.
Published: March 2003

Specimens of an unidentified species of the freshwater green alga Spirogyra were found to have abundant cruciate cellular inclusions up to 34 micrometers long. A crystalline nature was shown by birefringence in polarized light. Despite their large size and complex shape, these inclusions did not occur free in the large central vacuole. Instead, they were associated with cytoplasmic strands that spanned the space between gyres of the parietal spiral chloroplasts and with strands that suspended the nucleus in a cytoplasmic embayment of the central vacuole. Some crystals moved directionally along the cytoplasmic strands, and their movement was arrested by cytochalasin B, suggesting that actin microfilaments had a role in crystal movement. Solubility tests showed that the inclusions were composed of calcium oxalate; they dissolved rapidly in weak hydrochloric acid without effervescence, but they were not soluble in concentrated acetic acid or sodium hypochlorite. A colorimetric enzymatic test for oxalate was used to demonstrate microscopically the presence of oxalate and to quantify the amounts. The calcium oxalate crystals were surrounded by a water‐soluble organic matrix that retained the shape of the crystal even after demineralization. Scanning electron microscopy was used to examine the morphology of isolated crystals.
THE COMPOSITION AND TOXICITY OF DINOFLAGELLATE BLOOMS IN THE SALTON SEA, CALIFORNIA
Authors: Reifel K. M. , Tiffany  , McCoy M.P. , Hurlbert S.H.
Published: March 2003

Phytoplankton blooms have been implicated in mortality events of diverse groups of organisms including fish, birds and humans. About 300 species have been reported to form “red tides,” or surface discolorations due to high densities, but only 60–80 of these species produce harmful blooms. In marine systems, dinoflagellates account for 75% of all harmful algal bloom species. The Salton Sea is a large saline lake located in southeastern California, USA. The lake is eutrophic largely because it is in a closed basin and receives most of its input from agricultural and municipal wastewaters. Dinoflagellates comprise a significant portion of the phytoplankton biomass, particularly in winter, often resulting in “red” or “brown” tides. To date, 16 species of dinoflagellates have been identified from the Salton Sea, and many other unidentified forms have also been documented. In 1992, 150,000 eared grebes were found dead over a period of several months at the Salton Sea. This mortality event was among the largest of any bird species. The principal cause remains unknown, but algal toxins were suspected. A survey of the composition and toxicity of algal blooms was undertaken in 1999, and we report results from blooms where dinoflagellates dominated. Dominant species included Gonyaulax grindleyi, Gymnodinium spp., Gyrodinium uncatenum, Heterocapsa niei, and an unidentified scrippsielloid. Although most samples showed activity in a brine shrimp lethality assay, all were negative in a mouse bioassay. This evidence suggests that toxins from dinoflagellate blooms in the Salton Sea are not responsible for eared grebe mortality events.
REVISED CLASSIFICATION OF THE GENUS PACHYMENIA BASED ON MORPHOLOGICAL AND MOLECULAR CHARACTERS
Authors: Russell K. L. , Hurd C. L. , Nelson W.A. , Falshaw R. , Broom J.E.
Published: March 2003

Taxonomic discrimination in the genus Pachymenia (Rhodophyta) in New Zealand is based primarily on phenotypic characters of the thallus. The taxonomic problems raised by this classification method are due to highly variable thallus characters such as blade thickness, blade width, degree of thallus branching, and variation in anatomical characters. Delineation of species is further complicated by a lack of adequate knowledge about the responses of phenotype to environmental variation. There are currently three species recognized in this genus that are endemic to New Zealand: a prostrate species P. crassa, and two erect species, P. laciniata and P. lusoria. In this study, two approaches are used to investigate the current delineation of these species. Morphological and anatomical characters of field collected material and herbarium specimens from throughout the species' distributional ranges were quantified. Multivariate analyses were used to identify discrete phenotypic groups. Species relationships were further analyzed by quantifying the variation found within the internal transcribed spacer region (ITS) of the nuclear ribosomal DNA. The results obtained from both approaches will be discussed with regards to possible re‐classification of species relationships within this genus. We suggest that the two erect species should be merged, and the currently recognized P. lusoria should be separated into at least two taxonomic groups.
EFFECTS OF INCREASING UV‐B RADIATION DUE TO OZONE DEPLETION ON PHOTOSYNTHESIS OF ANTARCTIC CYANOBACTERIA
Authors: Tang E. P.Y. , Neale P.J , Fritz J.J.
Published: March 2003

Ground level ultraviolet‐B (UV‐B; 290–320 nm) fluxes in Antarctica have been increasing due to stratospheric ozone depletion. Although mat‐forming cyanobacteria are major component of freshwater algal biomass in Antarctica, little is known about their response to increasing ultraviolet radiation (UVR). The present study evaluated the sensitivity to UVR of two strains of mat‐forming cyanobacteria with different cell size, Phormidium murrayi (6.0 x 3.2 μm) and Schizothrix calcicola (2.2 x 2.3 μm). Cyanobacterial photosynthesis was measured under different UV spectral quality and quantity achieved by polychromatic filters with different cutoff wavelengths and neutral density screens. The productivity and irradiance data were used to generate biological weighting functions (BWF) for the assessment of UV inhibition on photosynthesis. The kinetics of UV inhibition, as determined by PAM fluorometry, differed between the two species so that inhibition of P. murrayi and S. calcicola were modeled based on UV‐irradiance and cumulative exposure, respectively. After a one hour exposure, BWF's did not differ between the two isolates of cyanobacteria despite their differences in cell size. To evaluate the negative impact of increased UV‐B exposure due to ozone depletion on cyanobacteria, the BWF's were applied to two solar spectra obtained from McMurdo Station, one on a day when the ozone hole was prominent (O3 = 170 Dobson units; DU = 10‐3 cm O3), and the other on a day with high ozone concentration (O3 = 328 DU). The decrease in ozone level would reduce productivity by 3–8%. Seasonal variation of UVR has a bigger impact on cyanobacterial productivity than ozone depletion.
ANALYSIS OF PORPHYRA RBC L DEMONSTRATES MULTIPLE MIGRATIONS OCCURRED BETWEEN THE NORTH ATLANTIC AND NORTH PACIFIC.
Authors: Teasdale B.W. , Lindstrom S.C. , Fredericq S. , Neefus C.D. , Mathieson A.C. , Taylor H. , West A.L. , Mercado S.T. , Piche N. , Klein A.S.
Published: March 2003

The taxonomic and evolutionary relationships between Porphyra of the boreal North Pacific (NP) and North Atlantic (NA) are being examined using near full length sequences of rbcL and the rbcL rbcS spacer (∼1420 bp). Phylogenetic analysis openface> 20 recognized species produced clusters containing both NP and NA species: Porphyra carolinenesis (NA) and Porphyra perforata (NP); Porphyra. leucosticta (NA) and Porphyra fucicola (NP); Porphyra‘amplissima’ (NA) and Porphyra cuneiformis (NP); Porphyra‘umbilicalis’ (NA) and Porphyra mumfordii (NP). A cluster of NP species including Porphyra abbottae, Porphyra kurogii, Porphyra pseudolinearis, and Porphyra pseudolanceolata formed a sister clade to P. fucicola (NP), P. leucosticta (NA) and several cryptic NA taxa. These results demonstrate that a number of “independent” migrations occurred between the North Pacific and Northern Atlantic. Furthermore these results confirm the hypothesis, based on similarities in morphology, isozymes, and karyotype, of Lindstrom & Cole (1992), that several sibling species pairs exist for Porphyra of the boreal North Pacific (NP) and North Atlantic (NA).
ASSOCIATION OF A FREE‐LIVING EUGLENA WITH A COLONIAL ROTIFER
Authors: Uzwiak D.J. , Triemer R.E.
Published: March 2003

Euglena agilis (syn. Euglena pisciformis) is a free‐living euglenoid found in brackish or fresh water. This species can be identified by its fusiform shape, single long flagellum, and prominent anterior eyespot. It can be distinguished from other euglenoids in part by its two to three large chloroplasts that run parallel to the length of the body, each with a single pyrenoid capped on two sides by paramylon. Euglena agilis is commonly found in our collecting ponds in central New Jersey. In two consecutive summers, we have found large numbers of these cells living symbiotically with the colonial rotifer Conochilus unicornis. We do not know if either organism benefits or is harmed in this relationship. For example, while we've seen the rotifers of the colony ingest other algae, we have not seen predation of the E. agilis (neither those embedded in the mucilaginous secretions of the rotifer nor swimming outside of the colony). This association is interesting for several reasons: 1) E. agilis is normally free‐living. 2) There are few known symbiotic relationships between euglenoids and rotifers. 3) E. agilis lose their long single flagellum when in the colony. We plan to use light and electron microscopy to investigate the ultrastructure of the E. agilis and its relationship to the rotifer colony.
MICROSCOPIC INVESTIGATIONS OF STROMBOMONAS WITH SPECIAL REFERENCE TO RELEASE FROM THE LORICA FOLLOWING CELL DIVISION
Authors: Zimmermann S. , Conforti V. , Triemer R.E.
Published: March 2003

The Euglenophyta include four genera of Euglena‐like cells enclosed in a lorica. Two of these genera, Trachelomonas and Strombomonas, are free swimming. These taxa have been differentiated and classified at the generic and species level based primarily on the morphology of their lorica. Numerous SEM studies have been conducted, yet few, if any, TEM descriptions exist, especially for Strombomonas. This study describes both the outer lorica and internal ultrastructure for Strombomonas sp. isolated from a fresh water pond in New Jersey. Additionally, we describe the release of daughter cells from the lorica following cell division. Two cells were observed within a single Strombomonas lorica following cytokinesis. When exposed to the light of the microscope, one or both of the cells emerged through the neck of the lorica. The released cells could easily be mistaken for Euglena species.
FIVE CRYPTIC SPECIES OF PORPHYRA FROM THE NORTHWEST ATLANTIC
Authors: Neefus C.D. , Mathieson A.C. , Yarish C. , Klein A. , West A. , Teasdale B. , Hehre E.J.
Published: March 2003

As one part of a multi‐institutional project on the biology of Porphyra, we collected extensive population samples of native Porphyra species from Long Island Sound to Nova Scotia. Samples were initially identified to species based on morphological features using taxonomic keys in Bird & McLaughlin (1992). Collections were analyzed using starch gel electrophoresis to look for intra‐specific variation useful in assessing population genetics. Isozyme variation in samples that had been originally identified as Porphyra leucosticta was far greater than expected. Samples from some collections differed by as much as 7 out of 7 loci. Other investigators have used starch gel electrophoresis to reveal cryptic differences in Porphyra that led to the descriptions of new species. In light of our isozyme results, we began a thorough examination of what had been identified as P. leucosticta in the northwestern Atlantic. The study included new collections as well as herbarium specimens. We examined morphology, habitat, seasonality, reproductive patterns, cell size & shape. We also extracted DNA and sequenced 1484bp of the rbcL gene. Based on this evidence, we feel we can circumscribe at least five distinct taxa of Porphyra not previously described from the northwestern Atlantic. Whether these represent new species, or previously described taxa from other geographic regions, we are not yet certain. We present here in detail, descriptions of each species along with summarized results of isozyme and DNA analyses.
ULTRASTRUCTURE AND CYTOCHEMISTRY OF SPERMATANGIAL DEVELOPMENT AND FERTILIZATION IN AGLAOTHAMNION OOSUMIENSE (CERAMIACEAE, RHODOPHYTA)
Authors: Chah O.K. , Lee I.K. , Kim G.H.
Published: March 2003

Spermatial development and fertilization processes were investigated by electron microscopy in Aglaothamnion oosumiense Itono. The spermatium is composed of two parts, an ovoidal head and two appendages projecting from each distal end. The appendages originate from spermatangial vesicles (SVs) and follow a developmental sequence beginning as amorphous material and ending as a fully‐formed fibrous structure compressed within the SVs. SV formation is due to contributions initially from endoplasmic reticulum and later from dictyosome‐derived vesicles. Chemical differentiation of the spermatial wall occurs early in its development. Calcofluor white does not label spermatial walls, indicating an absence of cellulose polysaccharides, which are abundant in vegetative cell walls. Liberated spermatia had a prophase arrested nucleus with a pair of polar rings. The cytoplasm of the trichogyne was connected with that of spermatia at the fertilization canal. The cytoplasm of the trichogyne was empty when the nuclear fusion between spermatium and carpogonium occurred.
COMPARISON OF GROWTH AND REPRODUCTION BETWEEN TWO POPULATIONS OF SARGASSUM SILIQUASTRUM IN PING CHAU, HONG KONG
Authors: Chan W.Y. , Ang P.O.
Published: March 2003

In Ping Chau Island of Hong Kong, two populations of Sargassum siliquastrum are present. One is in the shallow water of about 1 to 3 m Chart Datum (CD), and the other one in deeper water of 5 to 10 m CD. These two populations are separated by an extensive sand patch. Individuals of the “shallow” water population increased their size from a mean length of 8.3 ± 3.6 (SD) cm in Aug 1998 to a maximum of 48.2 ± 29.9 cm in early Jan 1999 before they started to die back. In the following year, they attained a minimum of 6.1 ± 3.8 cm in May 1999 and a maximum of 56.1 ± 23.6 cm in Dec 1999. Their reproductive period lasted for two to three months from Jan to Feb 1999, and again from Nov 1999 to Jan 2000. The “deep” water individuals increased their size to a maximum of 123 ± 50.8 cm at the end of Jan 1999 and started to die back in Feb, 1999. They again reached their maximum mean length in Jan 2000. Their reproductive period lasted for five to six months from Sept 1998 to Feb 1999 and again from Sept 1999 to Jan 2000. The “deep” water individuals tended to be longer in size and they attained their maximum growth a month later than the “shallow” water individuals. Their reproductive season tended to start earlier and lasted longer than those in the “shallow” water. These differences in the phenology of the two populations may be related to the temperature differences (up to 5° C difference in summer) between the two depths. Sargassum siliquastrum is likely to be a cold adapted species such that warmer temperature in the shallow water has compressed and shortened their rapid growth and reproductive period to within the few colder months in fall and winter.
TAXONOMY OF CERAMIUM (CERAMI‐ACEAE, RHODOPHYTA) FROM OREGON
Authors: Cho T.O. , Boo S. M. , Hansen G.
Published: March 2003

During a recent survey of marine red algae in Oregon, U. S. A., 6 of the 7 species of Ceramium reported from this state were collected in the intertidal zone. These included Ceramium californicum J. Agardh, C. cimbricum H. Petersen in Rosenvinge, C. codicola J. Agardh, C. gardneri Kylin, C. kondoi Yendo, and C. pacificum (Collins) Kylin. Detailed descriptions and illustrations of vegetative and reproductive development in C. californicum, C. codicola, and C. pacificum are presented for the first time in this paper. Descriptions are also given for C. cimbricum and C. kondoi, species previously only reported from elsewhere in the northwestern Pacific. These latter species were common on floating docks, sites where introduced species frequently occur. Ceramium eatonianum and C. washingtoniensis, the other 2 species known from Oregon, were found to belong to other genera or were not collected during this study.
INFECTIOUS DISEASES IN MACRO‐ALGAE: THE EFFECT ON HOST FITNESS
Authors: Correa J.A. , Faugeron S. , Martínez E. , Nimptsch J. , Paredes A.
Published: March 2003

The understanding of infectious diseases of algae has improved significantly in recent years, particularly in the area of recognition and signaling, key processes that determine the success or failure of host invasion by the pathogen. Ecological studies have also contributed to better understanding the role of diseases in wild stands of the affected hosts. An aspect that has received only limited attention is the effect of the infections on host fitness, and in this context, we report a first attempt to quantifying the effects of Pleurocapsa sp. (Cyanophyta) on the reproductive potential of its host Mazzaella laminarioides (Rhodophyta). Infections by Pleurocapsa trigger the development of tumors that can result in major changes in frond morphology and texture. Two populations of the host were considered in the study. Our results indicate that infections do not cause a significant effect on the density or quality of the reproductive structures (i.e. cystocarps and tetrasporangia). However, the number of spores, settlement rates, germination success and offspring survival, were all affected negatively by the endophytic infections. The reported information and field‐collected data, strengthen the notion that pathogens of algae may exert strong effects on their hosts at several levels, including reproduction. These effects can vary from host death during infections by highly pathogenic organisms to more subtle effects like those observed in the studied pathosystem. Infections by less aggressive pathogens, however, still may determine important effects at the population level by inducing differential mortality and reproductive success in infected individuals.
TEMPORAL AND SPATIAL PRODUCTION OF AGGLUTININS IN MARINE MACROALGAE FROM THE MEXICAN CARIBBEAN
Authors: De Lara‐Isassi G. , Álvarez‐Hernández S. , Lozano‐Ramírez C. , Hernández‐Soto N. , Dreckmann K. M.
Published: March 2003

The presence or absence of secondary metabolites in algae has been long discussed. There are several hypotheses to explain the synthesis of secondary metabolites in algae as a response to herbivory pressure, competence or predation. In this work we made a screening test of chlorophyte and rhodophyte species collected in different sites of the Caribbean sea in order to test them for agglutinins. The extracts were prepared in a phosphate buffer solution 100‐mM, pH 7.2 and filtered using 0.22 μm Millipore filters. Agglutination tests were done in microtiter‐plates using formalinized rabbit and human A, O, B erythrocytes. Agglutination titer was recorded and expressed as the reciprocal of the highest dilution showing positive results. A total of 31 samples were analyzed; seven Chlorophyta species and 11 Rhodophyta showed agglutinating activity. The species that showed activity variation included the chlorophytes, Caulerpa cupressoides, Caulerpa paspaloides, Halimeda opuntia and Penicillus capitatus and the rhodophytes, Chondria litoralis, Digenea simplex, Gracilaria cornea and Laurencia obtusa. The agglutinating activity of Liagora farinosa is reported for the first time. This research indicates that ecological pressures are an important factor in seaweeds agglutinins synthesis.
PHYTOPLANKTON COMMUNITY STRUCTURE: TEMPORAL VARIABILITY IN A TROPICAL UPWELLING ECOSYSTEM
Authors: Díaz‐Ramos J.R. , Muller‐Karger F.E. , Millie D. , Troccoli‐Ghinaglia L.E. , Subero‐Pino S. S. , Varela R.
Published: March 2003

The Cariaco Basin (Southeastern Caribbean Sea) is the largest anoxic basin of oceanic character. Its surface waters are affected by coastal upwelling during boreal winter and spring. Historical information on the phytoplankton communities in the basin is scarce. In November 1995, an oceanographic time‐series station was established at 10.5°N ‐ 64.66°W. In this study changes in the structure of the phytoplankton community in the upper 100‐m layer were studied. Monthly samples to determine phytoplankton abundance and pigment composition (HPLC) were collected from November 1995 to January 1999; water temperature was used as proxy for upwelling. Surface waters reached temperatures ≤24° C during the upwelling season, and surpassed 26° C during the rest of the year. A total of 300 species were found. Generally, the highest number of cells (>500 cells ml−1) were measured from January to April every year. Diatoms were the dominant group in terms of abundance, species composition (168 species) and pigments (Chl c and fucoxanthin) during this period. The abundance and marker pigment concentration (peridinin, but‐ and hex‐fucoxanthin) for other groups support this observation. During the rest of the year diatom and total abundance decreased markedly (<100 cells ml−1). Small organisms (<5 μm) became dominant. The maximum concentration values of zeaxanthin and But‐ and Hex‐Fuco in this period indicated the presence of cyanobacteria and prymnesiophytes. The sparse and relatively low concentration of Chl b, lutein and prasinoxanthin indicated that chlorophytes and its allies are a minor floral component.
LIGHT HARVESTING ANTENNAE SYSTEMS: LESSONS FROM SIMPLE ALGAE, THE ROLE OF SCIENTISTS, AND TRENDS
Authors: Gantt E.
Published: March 2003

Algae, with their variety of pigmentation and extant evidence of primary to tertiary endosymbiotic states, present rich opportunities for exploring evolutionary relationships. A strong link is suggested by the conservation of phycobilisome structure between red algal chloroplasts and cyanobacterial progenitors. Although phycobilisomes are the major antennae of photosystem II reaction centers in both groups, a chlorophyll (Chl)‐carotenoid light‐harvesting complex (LHC) evolved in rhodophytes around the photosystem I reaction centers. LHC‐polypeptides of all eukaryotic algae and green plants have high conservation of 8 putative Chl‐binding sites on three trans‐membrane helices, yet many different types of Chls and carotenoids serve in light harvesting in diverse algal groups. In view of the phylogenetic relatedness of LHC polypeptides (Durnford et al. 1999, J. Mol. Evol. 48:59) the Chl and carotenoid‐binding capability was examined with pigments from diverse algae. A recombinant P. cruentum polypeptide, LHCaR1, reconstituted with its own pigments functionally bound about 8.0 Chl a, and 4.0 zeaxanthin, comparable to native its polypeptides. Upon reconstitution with diatom pigments 7 Chl a, 1 Chl c, and 10 xanthophylls were bound per polypeptide, which participated in energy transfer to Chl a. Spinach pigments also bound to the polypeptide, incorporating a total of 8 Chl (both a and b) and ca. 4 xanthophylls, with energy transfer from lutein and Chl b to Chl a. These results suggest that the red algal LHCs retained the flexibility to bind different types of Chls and carotenoids. Such an ancestral feature may have contributed to the successful radiation of photosynthetic algae into varied light environments.
CURRENT STATUS OF THE INVASIVE GREEN ALGA CODIUM FRAGILE IN EASTERN CANADA
Authors: Garbary D.J. , Jess C.B.
Published: March 2003

Ten years after the initial discovery of Codium fragile in eastern Canada on the Atlantic coast of Nova Scotia, C. fragile has extended its range considerably to northern Nova Scotia, southern New Brunswick and Prince Edward Island (P.E.I.) in the Gulf of St. Lawrence. In all principal areas C. fragile subsp. tomentosoides is present. In two regions of Prince Edward Island, Codium is becoming extremely abundant, and is known by local fishers as the “oyster thief”. A potential second taxon of Codium was collected in 1999 at three sites in Malpeque Bay where it is locally abundant. These plants are distinguished from C. fragile subsp. tomentosoides by their smaller frond size, flatter utricle tops, smaller mucrons, and smaller gametangia. Principal component analysis distinguishes plants of the two types. The abundance of C. fragile on both hard bottom and soft bottom substrata suggests that it will become the dominant alga in many subtidal algal communities in eastern Canada.
A COCCOLITHOPHORID CALCIFYING VESICLE WITH A VACUOLAR‐TYPE ATPASE PROTON PUMP: CLONING AND IMMUNOLOCALIZATION OF THE V0 SUBUNIT c
Authors: Corstjens Paul L. A. M. , Araki Yoko , González Elma L.
Published: March 2003

Coccolithophorid calcification is subcellular. It relies on a single Golgi apparatus to produce coccoliths consisting of an organic baseplate and calcite. The calcification reaction is initiated in a calcifying vesicle derived from the trans‐most Golgi. We have cloned a subunit of a V (vacuolar)‐ATPase (EC 3.6.1.3., ATP phosphohydrolase) from a Pleurochrysis (Haptophyceae) cDNA library of transcripts expressed during calcification. Degenerate PCR primers were developed after alignment of the higher plant V‐ATPase subunit c genes to identify conserved consensus sequences. The library was screened with a homologous probe obtained by PCR. The cloned gene is found as a single copy on the P. cartarae (strain 136) genome and includes a 495‐base pair open reading frame encoding a 164 amino acid polypeptide and deduced molecular mass of 16.2 kDa. Its deduced amino acid sequence shows a close relationship to subunit c of the Vo domain of the vacuolar proton‐pumping ATPase of higher plants. An in vitro‐synthesized oligopeptide corresponding to the L2 extramembrane domain was used for rabbit immunization. Affinity‐purified antiserum detected a polypeptide band with an apparent molecular mass of 24 kDa in immunoblots of highly enriched coccolith vesicle membranes. Immunofluoresence microscopy showed antibody specificity for the membranes of isolated coccolith vesicles. This work provides support for the existence of an authentic, vacuolar‐type, proton‐pumping ATPase on coccolith vesicle membranes in a calcifying coccolithophorid.
EFFECT OF LIGHT ON VERTICAL MIGRATION AND PHOTOSYNTHESIS OF EUGLENA PROXIMA (EUGLENOPHYTA)
Authors: Kingston Michael B.
Published: March 2003

During daytime low tides, sediment‐inhabiting populations of Euglena proxima Dangeard migrate to the surface of intertidal sand flats to form large monospecific green patches near the Duke University Marine Laboratory in Beaufort, North Carolina. The effect of incident irradiance on the upward migration of E. proxima was studied by shading the sediment surface in the field with neutral density filters to 2, 20, 55, and 100% incident irradiance. The results of these in situ experiments revealed that E. proxima’s upward migration, as measured by population density or chl a concentration, was stimulated by decreasing incident irradiance: population densities and chl a concentrations on the sediment surface at 2% incident irradiance were greater statistically than at 100% full sunlight. In situ measurements of photosynthesis were performed by incubating 3‐mL aliquots of a cell suspension in scintillation vials containing 14C inorganic carbon beneath neutral density filters. These experiments revealed that E. proxima exhibited photoinhibition at 100% full sunlight, but this depression in photosynthetic performance at high light was absent when the cells were incubated in vials containing acid‐cleaned sediment. This amelioration of photoinhibition in vials containing sediment is most likely due to the downward migration of the population away from photoinhibitory light levels. These results cannot be interpreted as strictly photic effects because the temperature of the vials varied with the light treatment. The results of this study suggest that the vertical migration behavior of E. proxima and its photosynthetic physiology are intimately linked. Vertical migration provides a mechanism to deal with short‐term changes in irradiance and avoid photoinhibitory light levels.
NOTEPROROCENTRUM LIMA (DINOPHYCEAE) IN WATERS OF THE GREAT SOUTH CHANNEL NEAR GEORGES BANK
Authors: Maranda Lucie , Chan Christine , Martin Christopher
Published: March 2003

A 0–10 m plankton tow collected at one station in the Great South Channel near Georges Bank in June 1994 was rich in dinoflagellates, with the usually epibenthic Prorocentrum lima (Ehrenberg) Dodge present as the dominant species. Temperature and salinity profiles suggest that the phytoplankton population at this station may have been advected from waters on the southern flank of Georges Bank. This is the first unequivocal report of P. lima in the plankton community of the Great South Channel and its vicinity.
THE CHEMICAL FORM OF DISSOLVED SI TAKEN UP BY MARINE DIATOMS
Authors: Amo Yolanda Del , Brzezinski Mark A.
Published: March 2003

Results of past studies of the pH‐dependent Si uptake kinetics of Phaeodactylum tricornutum Bohlin suggested that the anion SiO(OH) is the chemical form of dissolved Si taken up by marine diatoms. We determined the chemical form of Si taken up by three other marine diatom species and P. tricornutum by examining the kinetics of Si use under two dramatically different SiO(OH):Si(OH)4 ratios in seawater by varying pH from ≈8 to ≈9.6. Uptake rates were determined using a precise and sensitive 32Si tracer methodology. The pH‐dependent uptake kinetics obtained for all species except P. tricornutum suggest that marine diatoms transport Si(OH)4. The half‐saturation constant (Km) varies strongly as a function of pH for all species when the substrate of transport is assumed to be SiO(OH). Kinetic curves for Thalassiosira pseudonana (Hustedt) Hasle et Heimdal, Thalassiosira weissflogii (Grunow) G. Fryxell et Hasle, and Cylindrotheca fusiformis Reimann et Lewin have statistically identical values of Km at each pH when the substrate for transport is assumed to be Si(OH)4 (T. pseudonana and T. weissflogii) or total dissolved silicon (C. fusiformis). In contrast, P. tricornutum exhibits unusual biphasic uptake kinetics: uptake conforms to Michaelis–Menten kinetics up to 15 to 25 μM, above which uptake increases linearly. This enigmatic response may have biased conclusions drawn from past experiments using this species. However, based on the consistency of the results for the three other species, a new model of Si transport in marine diatoms is proposed on the basis of the direct formation of a complex between the Si‐transport protein and Si(OH)4.
Ultrastructure of Lobocharacium coloradoense, gen. et sp. nov. (Chlorophyta, Characiosiphonaceae), an unusual coenocyte from Colorado
Authors: Kugrens Paul , Clay Brec L. , Aguiar Rosane
Published: March 2003

Light and electron microscopic descriptions are provided for Lobocharacium coloradoense, gen. et sp. nov., a unicellular coenocytic green alga isolated from a power plant's retaining pond in north‐central Colorado. Vegetative cells range from 120–230 μm in length and 80–120 μm in diameter in culture. The large vegetative cells are attached to substrates by small discoid attachment pads. The cells are multinucleate and consist of distinct cytoplasmic lobes, with each lobe containing a chloroplast and a basal nucleus. Chloroplasts are somewhat cone‐shaped in profile and stellate or lobed when viewed from the surface, and each has a central, basal pyrenoid. Hundreds of these cytoplasmic lobes occur within a cell, and thin cytoplasmic bridges interconnect the lobes. When a vegetative cell matures, each of the cytoplasmic lobes cleaves to form numerous fusiform zoospores or spherical isogametes. The biflagellate isogametes range in size from 4–10 μm, they lack a cell wall, they have a cup‐shaped chloroplast with a pyrenoid and stigma, and they have a nucleus close to the basal bodies. Isogametes are incapable of forming vegetative cells. Zoospores are biflagellate and fusiform, measuring 8–12 μm in length and 4–6 μm in diameter. Each zoospore has a cell wall, a single parietal chloroplast with a prominent pyrenoid in the center of the chloroplast, and a long oval stigma. Gamete and zoospore release involves a dissolution of the entire vegetative wall. Released zoospores usually settle and cluster near the vegetative cell from which they were produced, attach to the substrate with their flagella, and, shortly after losing their flagella, extrude mucilage through the flagellar pores in the wall to form a small discoid attachment pad. The incipient vegetative cell is fusiform and uninucleate, but it becomes more rounded and multinucleate as enlargement occurs. Most vegetative cells in culture become dormant, and the chloroplast becomes orange in color. Some cells form single aplanospores that can withstand desiccation, but occasionally numerous aplanospores may also be formed later in the larger vegetative cells.
A PCR IMMUNOASSAY METHOD FOR THE DETECTION OF ALEXANDRIUM (DINOPHYCEAE) SPECIES
Authors: Penna Antonella , Magnani Mauro
Published: March 2003

PCR primers targeting the internal transcribed spacer (ITS)‐5.8S rDNA regions specific for the genus Alexandrium were used to develop an ELISA assay method to detect and enumerate this genus in cultured isolates. The solid‐phase ELISA involves the application of a biotinylated labeled primer to target the specific ITS‐5.8S rDNA region; the PCR‐amplified products, generated in the presence of digoxigenin‐11‐deoxiuracil triphosphate nucleotide, are captured on the streptavidin‐coated microplate. The captured molecules were hybridized to an anti‐digoxigenin antibody conjugated with alkaline phosphatase. The presence and number of the Alexandrium cells in the samples resulted in a proportional appearance of color generated by the phosphatase activity in the presence of a chromogenic substrate and measured in a plate reader. This PCR and immunoassay solid‐phase assay proved to be a useful technique to detect the presence of Alexandrium sp. in cultured isolates and seawater samples.
PRODUCTION OF MUCILAGE BY THE ADRIATIC EPIPELIC DIATOM CYLINDROTHECA CLOSTERIUM (BACILLARIOPHYCEAE) UNDER NUTRIENT LIMITATION
Authors: Alcoverro Teresa , Conte Ersilia , Mazzella Lucia
Published: March 2003

The carbon partitioning of the epipelic diatom Cylindrotheca closterium (Ehrenberg) Reiman and Lewin isolated from the Adriatic Sea was studied in the laboratory under varying scenarios of nutrient limitation. Total number of cells, photosynthesis measured at 695 μmol photons·m−2·s−1 irradiance (P695‐μmol), chlorophyll (a+c) content, respiration, extracellular polymeric substances (EPS), total particulate carbohydrate (TPC), and dissolved carbohydrate were evaluated under nitrogen and phosphorus deficiencies in culture. The highest total number of cells was found in the control, whereas the nitrogen‐limited treatment showed the lowest value. During the transition phase of growth, photosynthesis in the nitrogen‐limited treatment was 3‐fold lower than in the phosphorus‐limited treatment and 4‐fold lower than in the control. Differences in respiration rates and chlorophyll (a+c) content were even more marked. Dissolved carbohydrate remained the same in all the treatments, whereas during the transition and stationary phase, EPS presented the highest values under phosphorus limitation and the lowest in the control treatment. The production of EPS was closely linked to the periods of carbon assimilation (transition phase) in the nutrient depleted treatments, especially in the phosphorus‐limited treatment. These results point out the relevance of the nutrient imbalance (nitrogen or phosphorus) in the production of EPS by the benthic or resuspended diatoms and suggest that these diatoms play an important role in nutrient‐unbalanced systems like sediments or marine snow.
KATAGNYMENE: CHARACTERIZATION OF A NOVEL MARINE DIAZOTROPH
Authors: Lundgren Pernilla , Söderbäck Erik , Singer Alon , Carpenter Edward J. , Bergman Birgitta
Published: March 2003

The marine planktonic cyanobacterial genus Katagnymene was described by Lemmermann in 1900 and is found in oligotrophic tropical and subtropical oceans. The genus comprises two species, K. pelagica Lemmermann and K. spiralis Lemmermann, and both were observed in most stations sampled during a cruise in the southwest Pacific Ocean in 1998. Katagnymene is nonheterocystous and characterized by single ensheathed trichomes that do not form colonies. Acetylene reduction‐GC demonstrated that natural populations of Katagnymene fixed nitrogen and that nitrogenase activity occurred exclusively in the light during a 12:12 light:dark cycle. Whole cell immunolocalization revealed that nitrogenase (the Fe protein) appeared in 7% of the total number of cells and that these were arranged in zones composed of consecutively arranged cells. At least one zone of nitrogenase‐containing cells per trichome was found. Nitrogenase was present throughout both the day and night, as shown by Western blotting, and in the same percentage of cells. Ultrastructural immunolocalization on sectioned trichomes also confirmed the presence and localization of nitrogenase in Katagnymene. Cultures of Katagnymene are able to grow on nitrogen‐free media and fix nitrogen only in the light. Finally, cloning and sequencing of nifH verified the diazotrophic nature of the genus Katagnymene and demonstrated a close relationship to members of the marine genus Trichodesmium.