bluuebunny/crossref_metadata_2025_split huggingface dataset:
PREDICTING THE KINETICS OF DISSOLVED INORGANIC CARBON LIMITED GROWTH FROM THE SHORT‐TERM KINETICS OF PHOTOSYNTHESIS IN SYNECHOCOCCUS LEOPOLIENSIS (CYANOPHYTA)1
Authors: Turpin David H. , Miller Anthony G. , Parslow John S. , Elrifi Ivor R. , Canvin David T. 
Published: August 2010

ABSTRACTThe blue‐green alga (Cyanobacterium) Synechococcus leopoliensis (Racib.) Komarek was grown in dissolved inorganic carbon [DIC]‐limited chemostats over the entire range of growth rates. At each growth rate, the kinetics of photosynthesis with respect to [DIC] and the maximal rate of photosynthesis (Pmax) were determined. The half‐saturation constant for [DIC]‐limited photosynthesis (K1/2DIC) for cells growing below 1.7 d−1 was constant (4.7 μM) whereas for growth rates between 1.7 d−1 and 2.1 d−1 (μmax) the kinetics of photosynthesis were multiphasic with an apparent K1/2DIC between 1.5–2.0 mM. Pmax increased in a linear fashion with growth rate for growth rates below 1.7 d−1. No trend in Pmax was apparent for growth rates greater than 1.7 d−1. These kinetic parameters were used to predict a growth rate versus [DIC] relationship. Results show that the Monod relationship is a physiologically valid expression of growth as a function of [DIC] provided (K1/2DIC) remains constant. The major change in (K1/2DIC) as μ approaches μmax results in the conclusion that two separate and distinct Monod equations must be used to describe growth as a function of DIC over the entire growth range. These results point to a major discontinuity in the μ vs. [DIC] curve at 1.7 d−1 which corresponds to the change from high to low affinity photosynthetic kinetics. We believe these results account for the previously described deficiencies of the Monod equation in describing [DIC]‐limited algal growth.
THE ULTRASTRUCTURE OF PYRAMIMONAS PSEUDOPARKEAE SP. NOV. (PRASINOPHYCEAE) FROM SOUTH AFRICA1
Authors: Pienaar Richard N. , Aken Mark E. 
Published: August 2010

ABSTRACTThe ultrastructure of Pyramimonas pseudoparkeae sp. nov., a member of the class Prasinophyceae occurring in tidal pools along the east, south and west coast of South Africa, is described. The cell surface is covered by three distinctive body scales whilst the flagellar surfaces possess four types of scales. The structure of these scales is described. P. pseudoparkeae resembles Pyramimonas parkeae Norris and Pearson but differs in the structure of the type 2 body scale. The symmetry and ultrastructure of the cell are described with special attention given to the flagellar apparatus. Preliminary information on the life cycle of this species is presented. This new species is compared with other closely related members of the genus Pyramimonas.
SEASONAL CHANGE IN THE DISTRIBUTION OF CELL SIZE OF COCCONEIS SCUTELLUM VAR. ORNATA (BACILLARIOPHYCEAE) IN RELATION TO GROWTH AND SEXUAL REPRODUCTION1
Authors: Mizuno Makoto , Okuda Kazuo 
Published: August 2010

ABSTRACTGrowth and sexual reproduction of the marine littoral diatom Cocconeis scutellum Ehrenb. var. ornata Grun. were investigated at 30 different combinations of temperature (5, 10, 14, 18, 22° C), irradiance (20, 60, 100 μE·m−2·s−1) and daylength (14:10 and 10:14 h LD cycle). Growth occurred at all combinations. The optimal growth was observed at 14–18° C, long daylength and highest‐to‐moderate irradiance, and at 18° C, short daylength and highest irradiance. Sexual reproduction on the other hand occurred between 5 and 18° C, and the optimal condition was 10–14° C and short daylength.Annual cyclic, and sesonal changes in the distribution of cell size (valve length) were observed in a field population. These changes were characterized by an annual minimum in mean cell size in autumn, an annual maximum in winter, a slight decrease from the mean in spring–middle summer, a rapid decrease from the mean in late summer–early autumn, and appearance of bimodal distribution of cell size in winter. These changes were caused by sexual reproduction in autumn, rapid growth in late summer–early autumn and slow growth in other seasons, and poor viability of small cells near the lower end of the size range.
PRODUCTIVITY OF THE FILAMENTOUS ALGA PITHOPHORA OEDOGONIA (CHLOROPHYTA) IN SURREY LAKE, INDIANA1
Authors: O'Neal Steven W. , Lembi Carole A. , Spencer David F. 
Published: August 2010

ABSTRACTBiomass, akinete numbers, net photosynthesis, and respiration of Pithophora oedogonia were monitored over two growing seasons in shallow Surrey Lake, Indiana. Low rates of photosynthesis occurred from late fall to early spring and increased to maximum levels in late spring to summer (29–39 mgO2·g−1 dry wt·h−1). Areal biomass increased following the rise in photosynthesis and peaked in autumn (163–206g dry wt·m−2). Photosynthetic rates were directly correlated with temperature, nitrogen, and phosphorus over the entire annual cycle and during the growing season. Differences in photosynthetic activity and biomass between the two growing seasons (1980 and 1981) were apparently related to higher, early spring temperatures and higher levels of NO3‐N and PO4‐P in 1981.Laboratory investigations of temperature and light effects on Pithophora photosynthesis and respiration indicated that these processes were severely inhibited below 15°C. The highest Pmax value occurred at 35°C (0.602 μmol O2·mg−1 chl a·min−1). Rates of dark respiration did not increase above 25°C thus contributing to a favorable balance of photosynthetic production to respiratory utilization at high temperatures. Light was most efficiently utilized at 15°C as indicated by minimum values of Ik(47 μE·m−2·s−1) and Ic (6 μE·m−2·s−1). Comparison of P. oedogonia and Cladophora glomerata indicated that the former was more tolerant of temperatures above 30°C. Pithophora's tolerance of high temperature and efficient use of low light intensity appear to be adaptive to conditions found within the dense, floating algal mats and the shallow littoral areas inhabited by this filamentous alga.
THE DEVELOPMENT AND REPRODUCTIVE MORPHOLOGY OF HALOSACCION AMERICANUM I. K. LEE (RHODOPHYTA, PALMARIALES)1
Authors: Mitman Grant G. , Phinney Harry K. 
Published: August 2010

ABSTRACT Halosaccion americanum, a member of Palmariaceae, was grown in culture from spores and the life history was critically examined by the use of scanning EM and light microscopy. A mature tetrasporangium of H. americanum produces four spores that germinate to form two male and two female gametophytes. The male gametophytes grow to maturity in approximately eight months and macroscopically resemble the tetrasporophyte. Following the first division of the tetraspore, the two‐celled female gametophyte consists of a vegetative cell and a carpogonium with trichogynes. Fertilization is accomplished by spermatia from male plants of the preceding generation, as male plants of the same season are immature. Spermatia are formed in a continuous layer over the surface of the mature male gametophytes and, when released, are entrained in long strands of mucous. Spermatia adhere to and fuse with trichogynes and, nuclear fusions presumably follow. The carposporophyte is absent; the new tetrasporophyte develops directly from the fertilized carpogonium. Growth of the sporophyte eventually obliterates the female gametophyte, and development into a mature tetrasporophyte proceeds over a period of approximately eight months. The development of H. americanum, with its extremely abbreviated female gametophyte stage and direct development of the tetrasporophyte from the zygote, indicates that this rhodophyte has the same life history as reported for other members of the Palmariales.
SHADE ADAPTED BENTHIC DIATOMS BENEATH ANTARCTIC SEA ICE1
Authors: Palmisano Anna C. , SooHoo Janice Beeler , White David C. , Smith Glen A. , Stanton Gregg R. , Burckle Lloyd H. 
Published: August 2010

ABSTRACTA dense community of shade adapted microalgae dominated by the diatom Trachyneis aspera is associated with a siliceous sponge spicule mat in McMurdo Sound, Antarctica. Diatoms at a depth of 20 to 30 m were found attached to spicule surfaces and in the interstitial water between spicules. Ambient irradiance was less than 0.6 μE · m−2· s−1 due to light attenuation by surface snow, sea ice, ice algae, and the water column. Photosynthesis‐irradiance relationships determined by the uptake of NaH14CO3 revealed that benthic diatoms beneath annual sea ice were light‐saturated at only 11 μE·m−2·s−1, putting them among the most shade adapted microalgae reported. Unlike most shade adapted microalgae, however, they were not photoinhibited even at irradiances of 300 μE·m−2·s−1. Although in situ primary production by benthic diatoms was low, it may provide a source of fixed carbon to the abundant benthic invertebrates when phytoplankton or ice algal carbon is unavailable.
SPECIES OF ANTITHAMNION (RHODOPHYCEAE, CERAMIACEAE) OCCURRING ON THE SOUTHEAST AFRICAN COAST (NATAL)1
Authors: Norris Richard E. 
Published: August 2010

ABSTRACTThree species of Antithamnion Naegeli were previously known from Natal, all reported since 1984. A more thorough collection of the flora in recent months has revealed that there are nine species in Natal, four of which are newly described. Vegetative characteristics are emphasized in this study of the taxonomy of Antithamnion, the most important being (1) size of axial cells, (2) form of whorl‐branchlets, (3) size of whorl‐branchlet basal cells, (4) size and shape of whorl‐branchlet terminal cells, (5) size and position of gland cells, (6) primary or secondary derivation of indeterminate lateral branches, and (7) the relationship of primary indeterminate branches, if present, to normal arrangement of whorl‐branchlets. Two closely related species, A. diminuatum Wollaston and A. eliseae sp. nov. have been grown in laboratory culture allowing for testing of stability and reliability of vegetative characteristics for use in taxonomic studies. Conclusions are that these criteria can be effectively used for these purposes. In addition to A. eliseae, A. nematocladellum, A. pterocladellum and A. adenocladellum also are described as new species. A tropical species previously known from the Caribbean and Red Seas, A. Iherminieri Nasr, a species previously recorded from Japan, A. secundum Itono, a species previously known from California and Japan, A hubbsii Dawson, and two species from Australia, A. diminuatum Wollaston and A. divergens (J. Agardh) J. Agardh, are also described from Natal.
PHOTOSYNTHETIC LIGHT‐HARVESTING FUNCTION OF VIOLAXANTHIN IN NANNOCHLOROPSIS SPP. (EUSTIGMATOPHYCEAE)1
Authors: Owens Thomas G. , Gallagher Jane C. , Alberte Randall S. 
Published: August 2010

ABSTRACTWhole cell absorption spectra of the Eustigmatophycean algae Nannochloropsis salina Bourrelly and Nannochloropsis sp. reveal the presence of a distinct absorption peak at 490 nm. The lack of chlorophylls b and c in these species indicates that this peak must be attributed to carotenoid absorption. In vivo fluorescence excitation spectra for chlorophyll a emission show a corresponding maximum at 490 nm. This peak is more clearly resolved than carotenoid maxima in other algal classes due to the absence of accessory chlorophylls. The carotenoid composition of the two Nannochloropsis species shows that violaxanthin and vaucheriaxanthin are the main contributors to 490 nm absorption. Violaxanthin accounts for approximately 60% of the total carotenoid in both clones. We conclude that light absorption by violaxanthin, and possibly by vaucheriaxanthin, is coupled in energy transfer to chlorophyll a and that violaxanthin is the major light‐harvesting pigment in the Eustigmatophyceae. This is the first report of the photosynthetic light‐harvesting function of this carotenoid.
COCCOLITH‐ASSOCIATED POLYSACCHARIDES FROM CELLS OF EMILIANIA HUXLEYI (HAPTOPHYCEAE)1
Authors: Barman Anton H. , de Jong Elisabeth W. , Thierry Remi , Westbroek Peter , Bosch Leendert , Gruter Marijke , Kamerling Johannes P. 
Published: August 2010

ABSTRACTCoccoliths of Emiliania huxleyi (Lohmann) Hay and Mohler, a unicellular calcifying alga, consist of calcite closely associated with an acidic, Ca2+‐binding polysaccharide. This polysaccharide is thought to play a regulatory role in coccolith synthesis by interfering with CaCO3 crystallization. Here we show that the polysaccharides from three different strains, A 92, L and 92 D, all inhibit the precipitation of CaCO3 in vitro to the same extent. The monosaccharide compositions of the A 92 and L polysaccharide are similar. The 92 D material, however, deviates from the other two: it contains significantly lower amounts of methylated sugars and ribose, and elevated levels of rhamnose and galactose. It also contains antigenic determinants not detected in the A 92 and L polysaccharides. In contrast to the latter two macromolecules the 92 D polysaccharide migrates as two bands upon polyacrylamide gel electrophoresis, possibly resulting from complexing with small amounts of protein. The coccolith polysaccharide from L cells, cultured at an elevated growth rate, also migrates as two bands. This phenomenon is due to an increase in molecular size distribution. The results suggest that certain properties of the molecule may be subject to variation without interfering with its function.
FLOW CYTOMETRIC ANALYSIS OF SPERMATOGENESIS IN THE DIATOM THALASSIOSIRA WEISSFLOGII (BACILLARIOPHYCEAE)1
Authors: Vaulot Daniel , Chisholm Sallie W. 
Published: August 2010

ABSTRACTFlow cytometry was used to detect and quantify sexual differentiation in the centric diatom Thalassiosira weissflogii (Grun.). Size (light scatter), chlorophyll, protein and DNA contents were measured for each cell throughout the process of differentiation. Male gametes were small round cells characterized by one complement of DNA and a lower protein and chlorophyll content than vegetative cells. Male gamete formation was induced by a long period of darkness (2 days) followed by a transfer to continuous light. Up to 30% of the initial cell population produced male gametes which appeared in the culture 14 h after release from darkness. Male gamete production was also detected in exponentially growing cultures in continuous light, but to a much smaller degree.
ABSENCE OF CAP MEMBRANES AS A CHARACTERISTIC OF PIT PLUGS OF SOME RED ALGAL ORDERS1
Authors: Pueschel Curt M. 
Published: August 2010

ABSTRACTThe current general model of the organization of a fully developed rhodophycean pit plug includes a cap membrane associated with each end of the plug. Continuity of the plasmalemma and cap membrane results in the plug core being extracellular. However, routine ultrastructural methods have not convincingly demonstrated cap membranes in the Bangiales or the Corallinales. In this study, a variety of fixation regimes that enhance membrane contrast were used in an attempt to detect cap membranes in representatives of these two orders. Although cap membranes were readily and clearly demonstrable by these methods in a representative of an order previously known to have cap membranes, they could not be detected in members of the Bangiales or Corallinales. Should the absence of cap membranes prove to be an invariant feature of these two orders, presence or absence of cap membranes will constitute a new character for phylogenetic analysis.It is proposed that the ancestral character state of red algal pit plugs was a homogeneous plug without caps and without cap membranes.
MASSIVE ACCUMULATION OF PHYTOENE INDUCED BY NORFLURAZON IN DUNALIELLA BARDAWIL (CHLOROPHYCEAE) PREVENTS RECOVERY FROM PHOTOINHIBITION1
Authors: Ben‐Amotz Ami , Gressel Jonathan , Avron Mordhay 
Published: August 2010

ABSTRACTThe effects of nanomolar to micromolar concentrations of the herbicide norflurazon were studied in Dunaliella bardawil Ben‐Amotz et Avron, a β‐carotene‐accumulating halotolerant alga. The large amount of β‐carotene which Dunaliella bardawil can contain, around 8% of the algal dry weight, is reduced to 0.2% by treatment with 100 nm norflurazon. Simultaneously, phytoene is accumulated to a similar level of about 8%. The gradual increase in phytoene content, in response to increasing norflurazon concentrations, corresponds to the decrease in β‐carotene, with no evident change in other isoprenoid intermediates. Carotene‐rich Dunaliella bardawil is substantially resistant to high‐intensity photoinhibition. This resistance is lost in cells grown to contain low β‐carotene and in the norflurazon‐treated phytoene‐rich cells. These observations are in agreement with the hypothesis that the accumulated β‐carotene in Dunaliella bardawil protects the cells against injury by excessive irradiation.
INCOMPLETENESS OF THE COCCOSPHERE AS A POSSIBLE STIMULUS FOR COCCOLITH FORMATION INPLEUROCHRYSIS CARTERAE(PRYMNESIOPHYCEAE)1
Authors: van der Wal. Paul , de Vrind Johannes P. M. , de Vrind‐de Jong Elisabeth W. , Borman Anton H. 
Published: August 2010

ABSTRACTPleurochrysis carteraeis a marine biflagellate that produces calcified structures called coccoliths. The coccoliths are formed inside the cells and released from the latter after formation. The light dependence of calcium incorporation in this species was studied using45Ca as a tracer. Cells exposed to a repeating cycle of 16 h of light and 8 h of darkness incorporated calcium in extracellular coccoliths at a more or less constant rate throughout a cycle. The cells divided during the dark periods with a concomitant decrease in size. Their size increased during the light periods Coccolith formation in cells incubated in continuous darkness was greatly reduced and finally ceased. These cells did not divide and did not increase in size. Removal of extracellular coccoliths prior to the calcium incorporation experiments stimulated coccolith formation both in dark‐incubated cells and in cells exposed to a repeating light‐dark cycle. Cells in the stationary phase of growth ceased producing coccoliths. Calcification could be induced in these cells by removal of the extracellular coccoliths. Based on these findings we suggest that cells ofPleurochrysis carteraetend to produce a complete cover of coccoliths and that the available cell surface is a factor controlling coccolith formation.
A modified photogrammetric technique for assessing age‐structures of elephant populations and its use in Kidepo National Park
Authors: CROZE HARVEY 
Published: August 2010

Summary(1) A modification of an aerial photographic technique for assessing the age‐structure of African elephant populations is introduced.(2) The method is quick, inexpensive, and provides important population dynamics information relevant to one of the most serious wildlife management problems in Africa–namely, the interaction of elephants and their habitats.(3) The method consists of photographing elephant breeding herd groups vertically, measuring their relative lengths, and then relating the lengths to a mean breeding herd growth‐curve.(4) An example of the application of the technique is given in an assessment of the age‐structure of two elephant populations in the Kidepo Valley National Park, Uganda.(5) The Kidepo populations are similar in age‐structure and are in general healthy. The similarities probably represent allopatric responses to the same climatic regime.(6) Peaks and troughs in the age‐structures are related to local rainfall, which indirectly aifects conception and mortality of young animals.(7) There are some obvious differences between the two populations, the home‐ranges of which exhibit differences in rainfall and habitat characteristics. The differences between the populations reaffirm the sensitivity of elephant population regulating mechanisms to local variations in climate and rainfall.(8) The relative roles of post‐mortem and observational techniques in elephant studies and the need for long‐term research are discussed.
A photographic ageing technique used on warthog
Authors: BRADLEY R. 
Published: August 2010

SummaryThe ratios of tusk‐length: snout‐width from a series of warthog (Phacochoerus aethiopicus) photographs were calculated and plotted against the date the photographs were taken. Regression lines, as well as the 95% confidence intervals, were calculated from the photographs and plotted. These regression lines fell into four distinct groups, representing Age Classes II through V. The average degree of error in the tusk‐length: snout‐width ratio was 3‐01 units, a figure well within the above 95% confidence intervals.
Age‐related changes in biological characteristics of human alveolar osteoblasts
Authors: Jiang S.‐Y. , Shu R. , Xie Y.‐F. , Zhang S.‐Y. 
Published: August 2010

AbstractObjectives:  Age‐related changes are common in many tissues and organs. However, cell‐related causes in human alveolar bone remain unclear. This study has been carried out to explore the possibility that advancing age might change the biological characteristics of alveolar osteoblasts (AOBs) in women.Materials and methods:  Alveolar osteoblasts from women donors (five women aged 33–38 years and five women aged 62–68 years) were cultured in vitro. The cells were serially passaged and maximal lifespan evaluated. Cell viability, ultramicrostructure and osteogenic differentiation ability were determined respectively, using MTT assay, transmission electron microscopy, alkaline phosphatase (ALP) activity assay and von Kossa staining assay. These parameters of the two groups of AOBs were evaluated.Results:  When compared with cells from young adult donors, AOBs from elderly women exhibited lower maximal lifespan (P < 0.05). Mean rate of population doubling was lower in elderly donor cells compared to those from young adult cells (P < 0.05). Organelles from AOBs of elderly donors were much fewer than those from young donors. MTT value of elderly donor cells was significantly lower than those of young adult donors from day 2 (P < 0.05). Relative ratio of ALP activity in elderly donor cells was significantly lower than those of the young womens’ cells at 8, 12, 16 and 20 days (P < 0.05). Calcium nodules of young adult donors’ specimens were significantly more numerous and larger than those from elderly donors.Conclusions:  Comparison of biological characteristics of AOBs from young adult women with those from elderly women in vitro revealed differences in proliferative capacity and bone formation functions, which decreased with aging. These data indicate that aging may play an important role in pathogenesis of human AOBs loss.
Fluctuations in European eel (Anguilla anguilla) recruitment resulting from environmental changes in the Sargasso Sea
Authors: BONHOMMEAU SYLVAIN , CHASSOT EMMANUEL , RIVOT ETIENNE 
Published: August 2010

AbstractEuropean eel decline is now widely observed and involves a large number of factors such as overfishing, pollution, habitat loss, dam construction, river obstruction, parasitism and environmental changes. In the present study, we analyzed the influence of environmental conditions in the Sargasso Sea and Atlantic ocean circulation on European glass eel recruitment success. Over a recent 11‐yr period, we showed a strong positive correlation between an original index of glass eel recruitment and primary production (PP) in eel spawning area. Moreover, PP was negatively correlated with temperature in the Sargasso Sea. Therefore, we used sea temperature as an inverse proxy of marine production. A close negative relationship has been found over the last four decades between long‐term fluctuations in recruitment and in sea temperature. These findings were reinforced by the detection of a regime shift in sea temperature that preceded the start of the decline in glass eel recruitment in the early 1980s. By contrast, variations in integrative indices measuring ocean circulation, i.e. latitude and strength of the Gulf Stream, did not seem to explain variations in glass eel recruitment. Our results support the hypothesis of a strong bottom‐up control of leptocephali survival and growth by PP in the Sargasso Sea on short and long time scales. We argue that sea warming in the eel spawning area since the early 1980s has modified marine production and eventually affected the survival rate of European eels at early life stages.