bluuebunny/crossref_metadata_2025_split huggingface dataset:
PHYSIOLOGICAL AND ULTRASTRUCTURAL RESPONSES OF CYCLOTELLA MENEGHINIANA (BACILLARIOPHYTA) TO LIGHT INTENSITY AND NUTRIENT LIMITATION1
Authors: Rosen Barry H. , Lowe Rex L. 
Published: November 2004

ABSTRACTPhotosynthetic characteristics and chloroplast ultrastructure of Cyclotella meneghiniana Kütz. were quantified while the organism was simultaneously adjusting to light and nutrient stress. Cells were grown in batch culture at either low or high light intensity on medium with a nitrogen/phosphorus molar ratio of 2:1 as a control, or with nitrogen or phosphorus deleted from the medium to create nutrient deficiencies. Analysis of variance indicated that light intensity, nutrient deficiency and duration of nutrient deficiency all had significant effects on cell growth, chlorophyll (Chl) concentration/cell, cellular fluorescence capacity (CFC), chloroplast volume and thylakoid surface density. Because interactions existed among nutrient deficiency, extent of nutrient deficiency, and light intensity, all three must be considered together in order to describe accurately the physiology and chloroplast ultrastructure of the diatom. Significant correlations were found between the Chl/cell or CFC/cell and chloroplast volume and thylakoid surface density. Through an increase in Chi concentration, chloroplast volume and thylakoid surface density, the cells successfully adapted to the conditions of low light intensity even while under nutrient stress. In contrast, less Chl/cell, smaller chloroplast volume and less thylakoid surface density were found at high light intensity.
STRUCTURE AND ABSOLUTE CONFIGURATION OF THE FLAGELLAR APPARATUS IN THE ISOGAMETES OFBATOPHORA(DASYCLADALES, CHLOROPHYTA)1
Authors: Roberts Keith R. , Stewart Kenneth D. , Mattox Karl R. 
Published: November 2004

ABSTRACTThe overall appearance of the flagellar apparatus in the isogametes ofBatophora oerstedii.J. Ag. is most like that which occurs in motile cells of the Ulvophyceae. Like other Ulvophyceae, the basal bodies overlap and are arranged in the 11/5 configuration, microtubular roots are arranged in a cruciate pattern and system II striated fibers are present. The basal body connective which generally lacks striation in the Ulvophyceae is clearly different inBatophora,being composed of two large non‐striated halves which connect to the anterior surface of each basal body and are then connected to one another by a distinctly fibrous centrally striated region. This variation in the basal body connective and the presence of two posteriorly directed system II striated fibers is clearly different from homologous structures reported in siphonous green algae of the Caulerpales. Based upon these variations and similarities among flagellar apparatus components in siphonous green algae, it is suggested that the Dasycladales and Siphonodadales are more closely related to one another than to the Caulerpales.
PHOTOINHIBITION: ALGAL RESPONSES TO BRIGHT LIGHT DURING DIEL STRATIFICATION AND MIXING IN A TROPICAL ALPINE LAKE1
Authors: Vincent Warwick F. , Neale Patrick J. , Richerson Peter J. 
Published: November 2004

ABSTRACTNear surface thermoclines form each day in the limnetic waters of Lake Titicaca (Peru‐Bolivia) and thereby retain phytoplankton under extreme irradiances. This bright light exposure results in strongly depressed chlorophyll fluorescence and photosynthesis which both decay (bright light) and recover (dim light) by first order rate kinetics. During each afternoon the phytoplankton are redistributed by wind‐induced mixing, and full recovery is accomplished soon after nightfall. In vivo fluorescence was measured over this diet cycle both with (Fb) and without (Fa 3‐(3,4‐dichlorophenyl)‐1,1‐dimethyl urea. Strongest bright light effects were on the parameter (Fa– Fa), a crude measure of operational photosystem II reaction centers (RC IIs). On dates of strong thermocline development, surface (FFa– Fa) was reduced to 5% or less of that for the mixed layer maximum. Fluorescence depression was greater in the lake than in Pyrex bottles incubated at fixed depths for 4 h. Ultraviolet light intensified the photoinhibitory response, but strong (Fb– Fa) depression could be induced by photosynthetically available radiation alone. In Lake Titicaca, photoinhibition apparently operates by reversible in‐activation of RC IIs. It occurs in the natural water column and is not simply an artifact affixed bottle incubations.
TIME LAPSE ANALYSES OF SEXUAL REPRODUCTION IN CLOSTERIUM EHRENBERGII (CONJUGATOPHYCEAE)1
Authors: Ichimura Terunobu , Kasai Fumie 
Published: November 2004

ABSTRACTThe process of sexual differentiation was studied using heterothallic clones of Closterium ehrenbergii Meneghini. The first visible sign of sexual reproduction was agglutination of two or more cells in a group and this was followed by gametangiogenic division and conjugation of gametangial cells. Movements of gametangial cells were carefully studied. Gametangial cells occasionally participated again in gametangiogenesis instead of proceeding directly to the formation of conjugation papilla. The whole process of sexual differentiation from vegetative cell to zygospore was considered to be basically similar in both of the two closely related mating groups, A and B, of C. ehrenbergii. Nevertheless, there were some differences between the two groups in patterns of the sexual differentiation. In Group A, vegetative cell division was completely suppressed by mixing the two complementary mating type clones together into the same medium with high light illumination. This suppression was not caused by the nitrogen depletion in the medium, but by the presence of cells of opposite mating type. In Group B, vegetative cell division and sexual reproduction occurred side by side repeatedly for several days.
STEROL DISTRIBUTION IN THE GENUS HETEROCAPSA (PYRRHOPHYTA)1
Authors: Alam Maktoob , Sanduja Radhika , Watson David A. , Loeblich Alfred R. 
Published: November 2004

ABSTRACTThe sterol composition of seven strains of marine peridinioid dinoflagellates comprising the four known species of Heterocapsa Stein was examined by gas chromatography‐mass spectrometry to determine the utility of these compounds in systematics. Cholest‐5‐en‐3β‐ol (cholesterol), 24‐methyl‐cholest‐5‐en‐3β‐ol (24‐methylcholesterol), 4α,24(S)‐dimethyl‐5α‐cholestan‐3β‐ol (4,24‐dimethylcholestanol), 4α,23,24(R)‐trimethyl‐5α‐cholest‐22‐en‐3β‐ol (dinosterol), 4α,23ξ,24ξ‐trimethyl‐5α‐cholestan‐3β‐ol (dihydrodinosterol), and an unknown sterol were detected. Sterol composition does not vary significantly from species to species within the genus Heterocapsa and thus cannot be used for species differentiation. Sterols may, however, have value in defining the properties of dinoflagellate taxa above the family level. Over the course of the growth curve for Heterocapsa niei (Loeblich) Morrill & Loeblich 4,24‐dimethylcholestanol and dinosterol covaried, suggesting that 4,24‐dimethylcholestanol is converted into dinosterol by a previously proposed bioalkylation scheme.
DEVELOPMENT OFDUMONTIA CONTORTA(DUMONTIACEAE, CRYPTONEMIALES) COMPARED WITH THAT OF OTHER HIGHER RED ALGAE1
Authors: Wilce Robert T. , Davis Andrew N. 
Published: November 2004

ABSTRACTThe vegetative development of juvenile and matureDumontia contorta(S. G. Gmelin) Ruprecht is characterized. New patterns of red algal thallus development are described.Dumontia contortahas an isomorphic life history with similarly branched erect gametophytes and tetrasporophytes. Erect plants are winter‐spring annuals that develop from a perennating crustose stage. Vegetative development ofD. contortaincludes both multiaxial and uniaxial systems. Juvenile thalli emerging from crustose bases are unbranched and entirely multiaxial; the main axis of a mature thallus is also multiaxial with the number of axial filaments decreasing acropetally as branches are initiated. Most lateral branches are uniaxial and do not rebranch. Thus, matureD. contortais characterized by multiaxiality in the lower main axis and by uniaxiality in its branches and in the tip region of the main axis. Our study corrects a number of inaccuracies in the literature and reinterprets the pattern of thallus development inD. contortain relation to stages of its vegetative growth. Development ofD. contortais compared with that of other higher red algae. Our results suggest an evolutionary derivation ofD. contortafrom the uniaxial, unbranchedD. simplex.
THE CRYSTALLINE CELL WALL OF TETRASELMIS CONVOLUTAE (CHLOROPHYTA): A FREEZE FRACTURE ANALYSIS1
Authors: Domozych David S. 
Published: November 2004

ABSTRACTA freeze fracture analysis of the cell wall of Tetraselmis convolutae (Parke et Manton) revealed the existence of a crystalline median layer consisting of regular repeating subunits of 27 nm. These circular subunits lie in curved, interlocking, longitudinal rows with some irregular discontinuities appearing in the subunit pattern of the crystalline lattice. A comparison with the cell walls of other green algal flagellates is presented, revealing similarities and suggesting evolutionary patterns.
A NUMERICAL TAXONOMIC STUDY OF NOSTOC AND ANABAENA1
Authors: McGuire Robert F. 
Published: November 2004

ABSTRACTThirty characteristics of 14 Nostoc and 10 Anabaena species were analyzed from previously published data. Using standard numerical taxonomic methods, simple matching coefficients were calculated and a phenogram drawn. The analysis revealed that some of the central characteristics of Nostoc are: a punctiforme stage; motile reproductive stage; plant mass with a dull to shiny luster, non‐veined surface, and nonfimbriate margin; some spherical vegetative cells; no cylindrical heterocysts; and some spherical, but no cylindrical akinetes. Some of the central characteristics of Anabaena that were revealed are: no punctiforme stage; a motile vegetative stage; plant mass with a shiny luster, veined surface, and fimbriate margin; no spherical vegetative cells; some cylindrical heterocysts; and some cylindrical, but no spherical, akinetes. In general, Anabaena has larger akinetes and vegetative cells than Nostoc. Based on 30 morphological characteristics and the clustering data of the phenogram, keys were constructed for the Nostoc and Anabaena species studied. The data clearly support two separate and distinct, though similar genera and, less sharply, the separation of the 24 species. The more useful characteristics for separation of the species are size and shape of akinetes, vegetative cells, and heterocysts; color and luster of plant mass; veined plant mass surface; margin fimbriate; and shape of plant mass in nature.
STRUCTURE, LIFE HISTORY AND SYSTEMATICS OF RHOICOSPHENIA (BACILLARIOPHYTA). V. INITIAL CELL AND SIZE REDUCTION IN RH. CURVATA AND A DESCRIPTION OF THE RHOICOSPHENIACEAE FAM. NOV.1
Authors: Mann David G. 
Published: November 2004

ABSTRACTThe initial epivalve of Rhoicosphenia curvata (Kütz.) Grun. differs from vegetative valves in having a strongly arched section, a wide hyaline marginal strip, no pseudosepta, an unthickened margin, and a terminal raphe fissure at the head pole. The initial epivalve is of the D type, with short raphe fissures. The epicingulum consists of three bands as usual, but they are narrower and more delicate than those of vegetative cells. The initial hypovalve and hypocingulum are similar in every way to those of vegetative cells, except for the rounded section of the hypovalve. During size reduction the almost isopolar outline of the initial valves and their immediate descendants gives way to an increasingly strong heteropolarity, and this is accompanied by changes in the relative lengths of the raphe slits and the shape of the central area. Different populations have different gametangium and initial cell sizes, suggesting the presence of races within the species. The structure of the initial cell indicates that Rhoicosphenia is less closely related to the monoraphid genera than to the gomphocymbelloid genera, confirming conclusions reached from studies of the vegetative cell and auxospore formation. Rhoicosphenia should therefore be separated into a new family, the Rhoicospheniaceae, which is described.
MALE GAMETES OF ATRACTOMORPHA ECHINATA HOFFMAN (CHLOROPHYCEAE)1
Authors: Hoffman Larry R. 
Published: November 2004

ABSTRACTMany naked gametes are produced in each fusiform, male gametangium of Atractomorpha echinata Hoffman and are liberated through irregularly shaped pores in the gametangial wall. They are typically biflagellate, pyriform or fusiform in shape, 6‐11 μm long, and only a few micrometers wide. A mature male gamete is characterized by: (i) a nucleus with condensed chromatin and no nucleoli, (ii) a reduced, starch filled chloroplast occupying a posterior position, and (iii) a cup shaped eyespot consisting of a single layer of plastoglobuli. The flagellar apparatus includes two types of flagellar roots alternating in a cruciate pattern. One type consists of two microtubules, while the other consists of microtubules of varying number, usually eight or nine, but rarely as many as eleven. The paired basal bodies are connected anteriorly by a broad, striated distal fiber; there is no dense apical cap as reported in Sphaeroplea sperm. A unique structure, consisting of three layers of small subunits (6–8 nm diameter) arranged in a paracrystalline array, is positioned beneath each basal body. Based on the structure of its male gametes, Atractomorpha clearly demonstrates affinity with the chlorophycean rather than the ulvaphycean line of evolution. Moreover, if phylogenetic affinities for the Sphaeropleaceae are to be sought among other groups of green algae, the Chlorococcales appears the most promising candidate.
Presence of HLA antibodies in single‐donor‐derived fresh frozen plasma compared with pooled, solvent detergent‐treated plasma (Octaplas®)
Authors: Sinnott P. , Bodger S. , Gupta A. , Brophy M. 
Published: November 2004

SummaryAdverse reactions to plasma transfusion are well documented. One of the most serious hazards of transfusion, transfusion‐related acute lung injury (TRALI), has nearly as high an incidence of mortality and major morbidity as that reported for the transfusion of incorrect blood components. The specific mechanisms of plasma component‐induced adverse reactions remain unclear, but a major contribution may be related to the presence of alloantibodies. In this study, a laboratory analysis was undertaken to determine the presence of HLA antibodies in leucodepleted single‐donor‐derived fresh frozen plasma (FFP). A comparison was made with a pooled plasma product that has undergone solvent detergent treatment. In total, 58 plasma samples from single‐donor units of leucodepleted FFP were tested along with samples from 12 units (three for each ABO blood group) of the pooled plasma (Octaplas®; Octapharma Ltd, Coventry, UK), for the presence of HLA antibodies. HLA‐specific enzyme‐linked immunosorbent assay (ELISA) methods were used to screen for their presence, and complement‐dependent cytotoxicity and flow cytometry analyses were used to further define their presence, specificity and class [immunoglobulin G (IgG)/IgM]. In the study groups, HLA antibodies were found to be present in five of the single‐donor units (9%) while the pooled plasma samples tested negative.
Analysis of human leukocyte antigen (HLA)‐G polymorphism in normal women and in women with recurrent spontaneous abortions
Authors: Abbas A. , Tripathi P. , Naik S. , Agrawal S. 
Published: November 2004

SummaryHuman leukocyte antigen (HLA)‐G is a non‐classical class I antigen. It has limited expression, but is high at the foetomaternal interface. This unique expression pattern of HLA‐G suggests that it might be important for survival of the foetus during pregnancy. In the present study, 120 women with recurrent spontaneous abortions (RSA) and 120 fertile control women were genotyped for the HLA‐G locus. This is the first report describing HLA‐G polymorphism in normal fertile and RSA women from India. The allele HLA‐G*010103 was higher in women with recurrent foetal losses. Interestingly, the HLA‐G*010105 and G*010108 alleles were totally absent in normal fertile women but present in RSA women with frequencies of 1.7% and 0.4%, respectively. Allele G*010107 was absent in both the groups. The frequency of the null allele G*0105N was high (13.8%) in our population as compared to other world populations. Our data support the hypothesis that HLA‐G polymorphism may contribute to recurrent foetal loss.
Climatic effects on the phenology of lake processes
Authors: Winder Monika , Schindler Daniel E. 
Published: November 2004

AbstractPopulations living in seasonal environments are exposed to systematic changes in physical conditions that restrict the growth and reproduction of many species to only a short time window of the annual cycle. Several studies have shown that climate changes over the latter part of the 20th century affected the phenology and population dynamics of single species. However, the key limitation to forecasting the effects of changing climate on ecosystems lies in understanding how it will affect interactions among species. We investigated the effects of climatic and biotic drivers on physical and biological lake processes, using a historical dataset of 40 years from Lake Washington, USA, and dynamic time‐series models to explain changes in the phenological patterns among physical and biological components of pelagic ecosystems. Long‐term climate warming and variability because of large‐scale climatic patterns like Pacific decadal oscillation (PDO) and El Niño–southern oscillation (ENSO) extended the duration of the stratification period by 25 days over the last 40 years. This change was due mainly to earlier spring stratification (16 days) and less to later stratification termination in fall (9 days). The phytoplankton spring bloom advanced roughly in parallel to stratification onset and in 2002 it occurred about 19 days earlier than it did in 1962, indicating the tight connection of spring phytoplankton growth to turbulent conditions. In contrast, the timing of the clear‐water phase showed high variability and was mainly driven by biotic factors. Among the zooplankton species, the timing of spring peaks in the rotifer Keratella advanced strongly, whereas Leptodiaptomus and Daphnia showed slight or no changes. These changes have generated a growing time lag between the spring phytoplankton peak and zooplankton peak, which can be especially critical for the cladoceran Daphnia. Water temperature, PDO, and food availability affected the timing of the spring peak in zooplankton. Overall, the impact of PDO on the phenological processes were stronger compared with ENSO. Our results highlight that climate affects physical and biological processes differently, which can interrupt energy flow among trophic levels, making ecosystem responses to climate change difficult to forecast.
Supply‐side controls on soil respiration among Oregon forests
Authors: Campbell J. L. , Sun O. J. , Law B. E. 
Published: November 2004

AbstractTo test the hypothesis that variation in soil respiration is related to plant production across a diverse forested landscape, we compared annual soil respiration rates with net primary production and the subsequent allocation of carbon to various ecosystem pools, including leaves, fine roots, forests floor, and mineral soil for 36 independent plots arranged as three replicates of four age classes in three climatically distinct forest types.Across all plots, annual soil respiration was not correlated with aboveground net primary production (R2=0.06,P>0.1) but it was moderately correlated with belowground net primary production (R2=0.46,P<0.001). Despite the wide range in temperature and precipitation regimes experienced by these forests, all exhibited similar soil respiration per unit live fine root biomass, with about 5 g of carbon respired each year per 1 g of fine root carbon (R2=0.45,P<0.001). Annual soil respiration was only weakly correlated with dead carbon pools such as forest floor and mineral soil carbon (R2=0.14 and 0.12, respectively). Trends between soil respiration, production, and root mass among age classes within forest type were inconsistent and do not always reflect cross‐site trends.These results are consistent with a growing appreciation that soil respiration is strongly influenced by the supply of carbohydrates to roots and the rhizosphere, and that some regional patterns of soil respiration may depend more on belowground carbon allocation than the abiotic constraints imposed on subsequent metabolism.
Soil respiration under prolonged soil warming: are rate reductions caused by acclimation or substrate loss?
Authors: Kirschbaum Miko U. F. 
Published: November 2004

AbstractThe world's soils contain a large amount of carbon so that even a fractionally small loss or gain could have a quantitatively important feedback effect on net CO2 emissions to the atmosphere. It is therefore important to fully understand the temperature dependence of soil‐carbon decomposition. Evidence from various observations can be used to quantify the temperature dependence of carbon efflux, but it is important to ensure that confounding factors, such as changing water relations or availability of readily decomposable substrate, are fully considered in inferring an underlying temperature response from observed response patterns.A number of recent findings from soil‐warming experiments have led to the suggestion that stimulation of soil‐carbon efflux by increasing temperature is only transitory before acclimation takes place and carbon efflux rates return to similar rates as before the increase in temperature. It is shown here that this response pattern can be explained through a simple two‐pool soil‐carbon model with no acclimation response needing to be invoked. The temporal pattern is, instead, due to depletion of readily decomposable substrate. It shows that findings of reduced respiration rate in soil‐warming experiments are consistent with unchanged high temperature sensitivity of organic carbon decomposition and affirms that there is, indeed, a danger of positive feedback between global warming and the release of soil organic carbon that can lead to further warming.
The response of two Glomus mycorrhizal fungi and a fine endophyte to elevated atmospheric CO2, soil warming and drought
Authors: Staddon Philip L. , Gregersen Randi , Jakobsen Iver 
Published: November 2004

Abstract Plantago lanceolata plants were grown under various environmental conditions in association with the mycorrhizal fungi Glomus mosseae, G. caledonium and a fine endophyte either individually or all together. Using a time‐course approach, we investigated the effects of elevated atmospheric CO2 (eCO2), soil warming and drought and their interactions on root length colonized (RLC) by mycorrhizal fungi and extraradical mycorrhizal hyphal (EMH) production. Plant growth responded as would be expected to the environmental manipulations. There was no plant growth‐independent effect of eCO2 on mycorrhizal colonization; however, EMH production was stimulated by eCO2, i.e. there was increased partitioning of below‐ground carbon to the EMH. Soil warming directly stimulated both percent RLC by the Glomus species and EMH density; soil warming did not affect RLC by the fine endophyte. Drought decreased percent RLC for the fine endophyte, but not for the Glomus species. The presence of one mycorrhizal fungus did not affect the response of another to the environmental variables. There was no evidence of any interactive effects of the environmental variables on RLC, but there were significant environmental interactions on EMH production. In particular, the stimulatory effects of eCO2 and soil warming on EMH density were not additive. The results are discussed in terms of the soil carbon cycle, highlighting some crucial gaps in our knowledge. If future environmental changes affect mycorrhizal fungal turnover and respiration, then this could have important implications for the terrestrial carbon cycle.