bluuebunny/crossref_metadata_2025_split huggingface dataset:
Global climate and the distribution of plant biomes
Authors: Woodward F. I. , Lomas M. R. , Kelly C. K. 
Published: October 2004

Biomes are areas of vegetation that are characterized by the same life–form. Traditional definitions of biomes have also included either geographical or climatic descriptors. This approach describes a wide range of biomes that can be correlated with characteristic climatic conditions, or climatic envelopes. The application of remote sensing technology to the frequent observation of biomes has led to a move away from the often subjective definition of biomes to one that is objective. Carefully characterized observations of life–form, by satellite, have been used to reconsider biome classification and their climatic envelopes. Five major tree biomes can be recognized by satellites based on leaf longevity and morphology: needleleaf evergreen, broadleaf evergreen, needleleaf deciduous, broadleaf cold deciduous and broadleaf drought deciduous. Observations indicate that broadleaf drought deciduous vegetation grades substantially into broadleaf evergreen vegetation. The needleleaf deciduous biome occurs in the world's coldest climates, where summer drought and therefore a drought deciduous biome are absent.
Traditional biome definitions are quite static, implying no change in their life–form composition with time, within their particular climatic envelopes. However, this is not the case where there has been global ingress of grasslands and croplands into forested vegetation. The global spread of grasses, a new super–biome, was probably initiated 30–45 Myr ago by an increase in global aridity, and was driven by the natural spread of the disturbances of fire and animal grazing. These disturbances have been further extended over the Holocene era by human activities that have increased the land areas available for domestic animal grazing and for growing crops. The current situation is that grasses now occur in most, if not all biomes, and in many areas they dominate and define the biome. Croplands are also increasing, defining a new and relatively recent component to the grassland super–biome. In the case of both grassland and croplands, various forms of disturbance, particularly frequent disturbance, lead to continued range extensions of the biomes.
A DINOFLAGELLATE CYST FROM ANTARCTIC SEA ICE1
Authors: Buck Kurt R. , Bolt Patricia A. , Bentham Wilfred N. , Garrison David L. 
Published: October 2004

ABSTRACTThe small (< 15 μm) hypnozygote of an autotrophic athecate dinofiagellate found in association with Antarctic sea ice had an external covering composed of approximately 60 plates, each of which was bounded by sutural ridging and possessed an intratabular process. A cingulum and sulcus were also evident. The ultrastructure of the cyst was increasingly dominated by storage bodies as the cyst matured, and the cell wall thickened from 0.2 to 0.8 μm over 2 months. This cyst has been encountered often but usually at low abundances (103−104 cells·L−1); however, the maximum abundances observed (106 cells·L−1) indicate that the formation of this cyst may play an important part in the ecology of sea ice communities.
PHOTOSYNTHESIS AND PHOTOSYNTHESIS‐COUPLED RESPIRATION IN NATURAL BIOFILMS QUANTIFIED WITH OXYGEN MICROSENSORS1
Authors: Glud Ronnie Nøhr , Ramsing Niels Birger , Revsbech Niels Peter 
Published: October 2004

ABSTRACTPhotosynthesis and respiration were analyzed in natural biofilms by use of O2 microsensors. Depth profiles of gross photosynthesis were obtained from the rate of decrease in O2 concentration during the first few seconds following extinction of light, and net photosynthesis of the photic zone was calculated from O2 concentration gradients measured at steady state. Respiration within the photic zone was calculated as the difference between gross and net photosynthesis. Two types of biofilms were investigated: one dominated by diatoms, and one dominated by cyanobacteria. High O2/CO2 ratios caused increased respiration especially within the diatom biofilm, which could indicate that photorespiration was a dominant O2‐consuming process. The rate of respiration was constant within both biofilms during the first 4.6 s following extinction of light, even when respiration was stimulated by high O2/CO2 ratio. The assumption of a constant rate of respiration during the dark period is an essential one for the determination of gross photosynthetic activity by use of O2 microsensors. We here present the first evidence to substantiate this assumption. The results strongly suggest that gross photosynthesis as measured by use of O2 microsensors may include carbon equivalents that are subsequently lost through photorespiration. Computer modeling of photosynthesis profiles measured after 1.1, 1.6, and 2.6 s of dark incubation illustrated how the actual photosynthesis profile could have appeared if it had been possible to do the determination at time 0. Diffusion of O2 during the up to 4.6‐s long dark incubations did not affect gross photosynthetic rate when integrated over all depths, but the apparent vertical distribution of the photosynthetic activity was strongly affected.
TWO MOTILE STAGES OF CHRYSOCHROMULINA POLYLEPIS (PRYMNESIOPHYCEAE): MORPHOLOGY, GROWTH, AND TOXICITY1
Authors: Edvardsen Bente , Paasche Eystein 
Published: October 2004

ABSTRACTEight months after the 1988 bloom of Chrysochromulina polylepis Manton et Parke in Skagerrak and Kattegat, off the coasts of Norway, Sweden, and Denmark, an alternate cell type carrying a scale complement different from that of authentic C. polylepis appeared in some clones isolated from the bloom. The cultures were recloned, and the development of the new clones was monitored. In clones with 100% cells of the alternate type, authentic cells reappeared, suggesting that the alternate cell type is a stage in the life cycle of C. polylepis and that transition between cell types occurs in both directions. Growth rates of clone cultures (termed a cultures) producing exclusively authentic cells, and of clone cultures (termed β cultures), capable of producing the alternate cell type, were compared at various combinations of temperature and photon fluence rate. The β cultures were less tolerant of high temperatures and photon fluence rates (≤20° C, 570 μmol photons·m−2·s−1) than were the α cultures. At lower temperatures and photon fluence rates (≤16° C, ≤90 μmol photons·m−2·s−1ss), β cultures grew better than α cultures. Relative abundance of the two cell types in β cultures changed in an apparently random manner during these experiments. Preliminary results from flow cytometric analyses indicated that cells of the alternate type were about twice the size and contained an equal or smaller amount of DNA per cell compared to the authentic cells. The β cultures were less toxic to Artemia nauplii than were the a cultures. Three other Chrysochromulina species tested were apparently nontoxic.
SEASONAL AND BETWEEN‐PLANT VARIABILITY IN THE MORPHOLOGY OF SARGASSUM MATHIESONII SP. NOV. (PHAEOPHYTA) FROM THE GULF OF MEXICO1
Authors: Kilar John A. 
Published: October 2004

ABSTRACT Sargassum mathiesonii sp. nov. is described from a population at the mouth of the Homosassa River, Homosassa, Florida. Patterns of morphological variation were quantified as well as the plant's phenology and ontogeny. Sargassum mathiesonii is dioecious (50/50 sex ratio), produces receptacles basipetally along laterals, and has vesicle pedicels that average 1–1.7 mm in length. As judged from coefficients of variation and measurements of between‐plant variation, vesicle diameter was the most stable continuous trait, followed by vesicle length, blade length: width ratio, blade width, and blade length. Anatomical variation was attributed primarily to ontogeny. Plants were smallest in March and April and grew to their maximum size in June (ca. 2 m). Biomass was augmented by additional main axes and primary laterals in October and receptacles in December. At maturity, male receptacles were longer and more loosely branched than female receptacles. A few vesicles developed viable oogonia in their cryptostomata and gave rise to fertile branches, situations previously unknown for Sargassum. Sargassum mathiesonii is determined to be morphologically and developmentally distinct from the lectotype and other North American populations of S. filipendula C. Ag. A more utilitarian approach to Sargassum taxonomy is achievable if species descriptions incorporate an understanding of morphological variability, reproductive periodicity, and ontogenetic patterns.
DISCOVERY OF A FERTILE PELAGOPHYCUS×MACROCYSTIS(PHAEOPHYTA) PUTATIVE HYBRID AND SUBSEQUENT PRODUCTION OF F2 SPOROPHYTES IN THE LABORATORY1
Authors: Coyer James A. , Engle John M. , Zimmerman Richard C. 
Published: October 2004

ABSTRACTA fertile putative hybrid of Pelagophycus porra (Lem.)Setch. × Macrocystis pyrifera (L.) was discovered in Big Fisherman Cove, Santa Catalina Island, California, in March 1986. The plant possessed a single, solid primary stipe that bifurcated into two secondary stipes, each with a hooked‐shaped pneumatocyst. A total of 15 blades, 14 with sori, were produced on two to three dichotomies above and below each pneumatocyst. Gametophyte development of spores released from sori and the resulting early sporophtes (2–3 mm) were typical of Laminariales. Gametophytes appeared within a day of spore germination, 500‐cell stage sporophytts within 3–4 weeks, and 2–3 mm sporophytes within 5–6 weeks. The cultures expired before branching patterns could be determined.
PATTERNS OF CELL SIZE CHANGE IN A MARINE CENTRIC DIATOM: VARIABILITY EVOLVING FROM CLONAL ISOLATES1
Authors: Armbrust E. Virginia , Chisholm Sallie W. 
Published: October 2004

ABSTRACTIsolates of the centric diatom, Thalassiosira weissflogii Grun., were maintained in exponential growth under constant, favorable conditions for nearly 2 years. During this interval, each culture underwent periodic increases and decreases in mean cell size, a behavior predicted for diatom populations alternating between sexual and asexual reproduction, respectively. The overall patterns of cell size change displayed by each culture, however, were unique. The maximum size of newly enlarged cells varied among isolates and within a given isolate over time. Consequently, both the timing and rate of increase in mean cell size also varied despite the fact that the minimum average cell size obtained by the various cultures was relatively constant. The most consistent feature among the isolates was the rate of decrease in mean cell size, a value determined by the physical constraints of the diatom frustule during mitotic divisions. We hypothesize that the extent of the variability exhibited by these cultures results from the fact that an inherent feature of diatom populations is a constantly changing genetic composition.
WATER MOTION AND MORPHOLOGY IN CHONDRUS CRISPUS (RHODOPHYTA)1
Authors: Gutierrez Luis M. , Fernández Consolación 
Published: October 2004

ABSTRACTMorphological variability of intertidalChondrus crispusStackh. fronds along a small open rocky coast was related to wave exposure and emersion. Cluster analysis revealed two well‐defined morphologies: filiform and planiform, named the N morphotype and B morphotype, respectively. We propose a rapid method of classifying fronds based on the morphology of the cross section at half the height on the thallus. The N morphotype is characterized by fewer dichotomies per unit length, a circular cross section with a large inner cortex, and narrow fronds. It is abundant at low intertidal and exposed sites. The B morphotype is characterized by more dichotomies, smaller sizes, a subelliptical or flattened cross section, and broad fronds. It is abundant at high intertidal sites in sheltered areas. Regression analysis revealed a major effect of water movements on frond morphology with respect to tidal level, which was more evident at high intertidal levels. No relationships were observed between morphology and life history phases.
FINE STRUCTURE OF A TERRESTRIAL CYANOBACTERIAL MAT FROM ANTARCTICA1
Authors: Davey Martin C. , Clarke Ken J. 
Published: October 2004

ABSTRACTThe fine structure of a cyanobacterial mat collected from the fellfield ecosystems of Signy Island, Antarctica, was examined using some novel light and scanning electron microscope techniques. The mat was up to 5 mm thick and was distinctly layered. The surface of the mat consisted of nonliving material above a zone of Phormidium autumnale (Ag.) Gom. filaments. We suggest that the surface layer protects the cyanobacterium from the effects of desiccation or high irradiance. Lower layers were less structured than the upper layer and included other taxa of cynobacteria and eukaryotic algae, although still dominated by Phormidium. The lowest layers consisted of dead organic material. The mat bound large amounts of inorganic material within and between the subsurface layers.
EVIDENCE OF AN ORGANIC MATRIX FROM DIATOM BIOSILICA1
Authors: Swift Debbie M. , Wheeler A. P. 
Published: October 2004

ABSTRACTMost biominerals appear to be composites of organic material and mineral. Whether biosilica is such a composite is unresolved because of a lack of evidence for such organic components. We present evidence that organic material exists within diatom biosilica and can be extracted using HF/NH4F solutions from frustules isolated from Cyclotella meneghiniana Kütz and diatomaceous earth. To eliminate organic casing on the silicified frustules as a source of organic materials, the casing was removed by oxidation of frustules with NaOCl before extraction. The removal of the casing was confirmed in that oxidized frustules no longer displayed the ability to be stained with ruthenium red and fluorescamine. Frustules examined with EDXA showed an emission peak from sulfur before treatment but no peak following treatment, indicating that oxidation removed organic sulfur. The organic material obtained from extracts of fresh frustules contained both soluble and insoluble components. Only soluble material was evident in extracts from diatomaceous earth. The soluble material appears to contain glycoproteins with relatively high levels of serine and glycine. The soluble proteins from fresh frustules also appear to be phosphorylated. Indirect evidence is presented that suggests the soluble proteins may contain regions of primary structure enriched in anionic amino acids. The soluble extracts differ from general cell contents when the two fractions are compared, suggesting that frustules contain specialized organic material. The identification of silica‐specific organic material suggests that mineralization in diatoms may be in part matrix‐mediated.
SEQUENCE AND PHYLOGENY OF THE PSAB GENE OF PYLAIELLA LITTORALIS(PHAEOPHYTA)1
Authors: Assali Nour‐Eddine , Goër Susan Loiseaux‐de 
Published: October 2004

ABSTRACTThe psaB gene codes for one of two highly conserved P700 chlorophyll a apoproteins of photosystem I. This gene was cloned from the brown alga, Pylaiella littoralis (L.) Kjellm., and its primary sequence was determined. The inferred amino acid sequence of the P. littoralis protein was compared to homologous sequences from land plants, green algae, and a cyanobacterium. The psaB protein sequence is very conserved in all the examined taxa, and an unrooted phylogenetic tree, generated from a distance matrix, shows that the P. littoralis gene is closer to that of the cyanobacterium Synechocossus sp. PCC 7002 than are those of green algae, land plants, and Euglena gracilis.
PRINTZINA GEN. NOV. (TRENTEPOHLIACEAE), INCLUDING A DESCRIPTION OF A NEW SPECIES1
Authors: Thompson Rufus H. , Wujek Daniel E. 
Published: October 2004

ABSTRACTExamination of Trentepohlia Martius species indicated significant morphological diversity within the genus. This diversity forms the basis for the description of a new genus, Printzina Thompson and Wujek. The generic taxonomy is based on the nature of its superficial growth on leaves or twigs and a papilla pore basal on the sporangium, adjacent to the area of attachment. Certain nomen‐clatural treatments were required: the transfer of nine species from Trentepohlia and the description of one new species, Printzina ampla.
DISTRIBUTION AND RECRUITMENT OF SUBTIDAL GENICULATE CORALLINE ALAGE1
Authors: Konar Brenda , Foster Michael S. 
Published: October 2004

ABSTRACTGeniculate coralline algae are common members of kelp forest communities. The structure provided by their stiff branches greatly influences the abundance and species composition of benthic animals and can affect associated algae by inhibiting recruitment, but the branches are themselves substrate for a large number of other taxa. However, other than qualitative observations, little is known about the within‐site distribution, recruitment, and growth of these algae. We examined the distribution of the dominant corallines at a subtidal site in central California. Abundances of Calliarthron tuberculosum (Post. & Rupr.) Dawson, Bossiella californica ssp. schmittii (Manza) Johans., Calliarthron cheilosporioides Manza, Corallina vancouveriensis Yendo, and unidentifiable juveniles were determined at depths of 10, 15, and 20 m and on horizontal rock, vertical rock, and cobble. Calliarthron tuberculosum was most abundant (≤39% cover) at all depths, growing primarily on horizontal surfaces. Vertical surfaces and cobbles were dominated by B. californica ssp. schmittii (40 and 15% cover, respectively). These two most abundant species had the highest cover at 15 m. Calliarthron cheilosporioides and C. vancouveriensis were relatively rare (<1% cover) and generally grew on horizontal rocks and at shallower depths. Unidentified juveniles were also rare and occurred mainly on horizontal rocks and cobbles at 20 m.The settlement and growth rates of coralline crusts and the initiation and growth rates of young erect fronds from these crusts were determined in clearings made in the spring and fall at the three depths. Crust densities and diameters were highest at 10 m and in spring clearings. Settlement and growth tended to decrease with increasing depth. Trends were similar in fall clearings, but initial settlement was lower. Initiation and growth of fronds decreased with depth and were also higher in fall clearings. These variations in depth and substrata distribution, as well as settlement and growth, suggest there is considerable variation in the population biology between species in this group of subtidal plants.
FATTY ACID DISTRIBUTION AMONG SOME RED ALGAL MACROPHYTES1
Authors: Levy Israel , Maxim Corina , Friedlander Michael 
Published: October 2004

ABSTRACTMacrophytic members of the Rhodophyta, which were grown under controlled conditions, were analyzed for their fatty acid distribution. Significant differences were found between some species of the Gelidiales and Gracilariales. Two dominant polyunsaturated fatty acids of the 20 carbon chain group, 20:4ω6 and 20:5ω3, were found in all the Gelidiales species, whereas only 20:4ω6 was found in the Gracilariales species. An inverse relationship between the content of these two polyunsaturated fatty acids in Gelidiales species and among the two groups of species are reported and discussed. All other fatty acid characteristics were more or less similar in these two orders. We cannot draw any solid conclusion about the relationship between Gracilariopsis cf. lemaneiformis (formerly Gracilaria lemaneiformis) and the genus Gracilaria, since our results (the existence of 20:4ω6 and 20:5ω3 in Gracilariopsis) contradict results found by other researchers. The diverse growth conditions of photon flux density and temperature caused some differences in the distribution of the fatty acids in each species. These differences could not explain the different results in similar species reported in the literature.
DEVELOPMENT OF THE ENDOPARASITIC DINOFLAGELLATE AMOEBOPHRYA CERATII WITHIN HOST DINOFLAGELLATE SPECIES1
Authors: Fritz Lawrence , Nass Monica 
Published: October 2004

ABSTRACTThe endoparasitic dinoflagellate Amoebophrya ceratii Koeppen occurs in coastal waters of Nova Scotia within cells of two dinoflagellate hosts, a Scrippsiella species (probably S. trochoidea (Stein) Loeb. III) and Dino‐physis norvegica Claparede & Lachman. We describe the development of the endoparasitic stage (the trophont) of A. ceratii within host cells using light and electron microscopy. After entry into the host, the trophont grows and expands until most of the host cell is occupied by the parasite. Growth is marked by a proliferation of trophont nuclei and flagella and by the formation of numerous lobes, each of which possesses a characteristic dinoflagellate amphiesma. The mature endoparasitic trophont is recognized at the light microscopic level as a beehive‐shaped structure that consists of numerous lobes of the developing motile sporont cells and a mastigocoel cavity containing the sporont flagella.
ORGANIZATION OF THE CHLOROPLAST GENOME OF THE FRESHWATER CENTRIC DIATOM CYCLOTELLA MENEGHINIANA1
Authors: Bourne Carol M. , Palmer Jeffrey D. , Stoermer Eugene F. 
Published: October 2004

ABSTRACTWe constructed a complete physical map and a partial gene map of the chloroplast genome of Cyclotella meneghiniana Kützing clone 1020‐1a (Bacillariophyceae). The 128‐kb circular molecule contains a 17‐kb inverted repeat, which divides the genome into single copy regions of65 kb and 29 kb. This is the largest genome and inverted repeat found in any diatom examined to date. In addition to the 16S and 23S ribosomal RNA genes, the inverted repeat contains both the ndhD gene (as yet unexamined in other diatoms) and the psbA gene (located similarly in one of two other examined diatoms). The Cyclotella chloroplast genome exists as two equimolar populations of inversion isomers that differ in the relative orientation of their single copy sequences. This inversion heterogeneity presumably results from intramolecular recombination within the inverted repeat. For the first time, we map the ndhD, psaC, rpofi, rpoCl, and rpoC2 genes to the chloroplast genome of a chlorophyll c‐containing alga. While the Cyclotella chloroplast genome retains some prokaryotic and land plant gene clusters and operons, it contains a highly rearranged gene order in the large and small single copy regions compared to all other examined diatom, algal, and land plant chloroplast genomes.
SEPARATING TABELLARIA (BACILLARIOPHYCEAE) SHAPE GROUPS BASED ON FOURIER DESCRIPTORS1
Authors: Mou Daiqing , Stoermer Eugene F. 
Published: October 2004

ABSTRACTA random sample of 490 Tabellaria specimens was analyzed using the harmonic amplitudes of the Fourier transformations of their valve outlines as shape descriptors. Principal component analysis (PCA) was applied to the sample to reduce dimensionality. The problem of non‐normal distribution of these descriptors due to cell division was solved by sub‐sectioning the entire data set based on its distribution on the first three components (PC1, PC2, and PC3) of the overall PCA. Each of the subsets was then analyzed by PCA. Shape groups from subset clusters were compared with one another and then similar groups were congregated into one growth series. Eight distinct shape groups were found. The results agree with some previous classical observations on the genus and at the same time reveal many new morphological characteristics related to valve shape. These new characteristics are impossible to obtain without appropriate specimen sampling, quantitative shape description, and data analysis techniques.