bluuebunny/crossref_metadata_2025_split huggingface dataset:
Subclinical abnormalities of glucose metabolism in Brazilian women with a history of gestational diabetes mellitus
Authors: Pimenta Walkyria P. , Calderon Iracema M. P. , Cruz Ney S. , Santos Maria Luiza , Aragon Flávio F. , Padovani Carlos Roberto 
Published: November 2004

Background.  To evaluate insulin release and insulin sensitivity in women with prior gestational diabetes mellitus (GDM) to gain a better understanding of type 2 diabetes pathogenesis.Methods.  GDM women were individually matched for age, body mass index, and waist/hip ratio with those who were normal glucose tolerant in a previous pregnancy (NGT). All women presented with normal glucose tolerance. Twenty pairs were submitted to the oral glucose tolerance test (OGTT) with plasma glucose, insulin, and C‐peptide determinations. Of the 20 pairs, 18 participated in hyperglycemic (10.0 mmol/l) clamp experiments with frequent plasma glucose and insulin determinations, allowing us to calculate first‐ and second‐phase insulin release and the insulin sensitivity index. GDM and NGT women were compared using Student's t‐test, the Mann–Whitney U‐test, Friedman's non‐parametric test, and the two proportion test for independent groups.Results.  GDM women showed higher glycosylated hemoglobin values; at OGTT, they showed late insulin peak with increased plasma insulin levels only during the second hour, and a similar plasma C‐peptide response despite a higher plasma glucose curve; during hyperglycemic clamp procedures, they showed similar biphasic insulin release and insulin sensitivity index. Considering that a woman with previous GDM had a defect in insulin release and/or insulin sensitivity, if its magnitude was at least 25% lower than that of the matched NGT woman, 43.8% showed impairment of first‐phase insulin release and 55.6% insulin resistance.Conclusions.  GDM women showed some degree of glucose intolerance. It is therefore necessary to follow them for a longer time.
Reproductive factors and extreme levels of maternal serum alpha‐fetoprotein: a population‐based study
Authors: Lei Ulrikke , Wohlfahrt Jan , Christens Peter , Westergaard Tine , Lambe Mats , Nørgaard‐Pedersen Bent , Melbye Mads 
Published: November 2004

Background.  Levels of maternal alpha‐fetoprotein (AFP) are increased during multiple gestations and preeclampsia but little is known regarding AFP levels in relation to other reproductive factors. Consequently, the objective of this work was to describe the possible relationship between AFP levels during pregnancy and maternal age at birth, maternal age at first birth, parity, time since previous birth and gender of the offspring.Methods.  Based on national registries we obtained the reproductive history on a population‐based cohort of 44 227 women who had serum AFP levels determined in gestational weeks 14–21 and whose present and previous pregnancies resulted in live‐born singletons.Results.  Many previous births and an interval of less than 2 years since last birth were significantly associated with extremely low levels of AFP in the mother. However, age at first birth and age at present pregnancy did not influence the AFP level. Women who gave birth to a girl had AFP levels that were 5%[95% confidence interval (CI) 4–6%] lower than those of women who had a boy. Adjustment for birthweight did not significantly affect the estimate.Conclusions.  Low serum AFP levels in pregnancy are significantly correlated with high parity and with a short interval between births. The significantly lower levels of AFP in women who gave birth to girls could indicate a possible gender‐specific regulatory mechanism.
Infertility and celiac disease: do we need more than one serological marker?
Authors: Shamaly Hussein , Mahameed Ahmad , Sharony Asher , Shamir Raanan 
Published: November 2004

Objectives.  Celiac disease (CD) prevalence is higher in women with infertility. Our study aims were to evaluate the prevalence of undiagnosed CD in Arab infertile women and to explore the usefulness of using more than one serological marker in the diagnostic screening for CD in this population.Methods.  Women with unexplained infertility (n = 192) and age‐matched healthy controls (n = 210) were prospectively enrolled. Serum was tested for human tissue transglutaminase antibodies (TTG), antiendomysial antibodies (EMA), and immunoglobulin A. Intestinal biopsy was offered to women with positive serology or immunoglobulin A (IgA) deficiency.Results.  CD was diagnosed in five infertile women (2.65%) and in one control (0.5%) (p = 0.11). Gastrointestinal complaints were present in 60% (three of five) of women with CD and 11.8% (22 of 187) of women without CD (p = 0.017). Anemia was reported in 80% of infertile women with CD and 4.8% of infertile women without CD (p = 0.0001).Conclusions.  Undiagnosed CD is prevalent in Arab infertile women as well as in Arab women in general. CD in Arab infertile women is frequently associated with gastrointestinal complaints and anemia. EMA testing is sufficient in suspected cases.
SOMATIC CELL FLAGELLAR APPARATUSES IN TWO SPECIES OF VOLVOX (CHLOROPHYCEAE)1
Authors: Hoops Harold J. 
Published: November 2004

ABSTRACTThe somatic cell flagellar apparatuses of Volvox carteri f. weismannia (Powers) Iyengar and V. rousseletii G. S. West have parallel or nearly parallel basal bodies which are separated at their proximal ends. The four microtubular rootlets alternate between two and four members, and all are associated with a striated microtubular associated component (SMAC) that runs between the basal bodies. In addition, each half of the flagellar apparatus apparently rotates during development and loses the 180° rotational symmetry characteristic of most unicellular chlorophycean motile cells. All of these features appear necessary for efficient motion of a colony composed of numerous radially arranged cells. However, the structural details of the flagellar apparatuses of these two species differ. The distance between flagella is greater in V. rousseletii than in V. carteri. One distal striated fiber and two proximal striated fibers connect the basal bodies in V. carteri, but both types of fibers are absent from V. rousseletii. In the latter species, a striated fiber wraps around each of the basal bodies and attaches to the rootlets and the SMAC. No such fiber is present in V. carteri. Since the similarities in the flagellar apparatuses can be explained as a result of adaptation for efficient colonial motion in organisms with similar colonial morphology, the differences suggest a wider phylogenetic distance than previously believed.
PHOSPHORUS STATUS AND CYTOPLASMIC STRUCTURES IN SCENEDESMUS (CHLOROPHYCEAE) UNDER DIFFERENT METABOLIC REGIMES1
Authors: Tillberg Jan‐Eric , Barnard Tudor , Rowley John R. 
Published: November 2004

ABSTRACTPhosphorus deficiency affects the anatomy of the unicellular green alga Scenedesmus obtusiusculus Chad. and influences the distribution of other inorganic elements in the cell in addition to phosphorus. Scenedesmus was grown under standard conditions with or without phosphorus. Cells were then cultured with phosphorus under conditions favouring glycolysis, respiration, or photophosphorylation for 2 h or photosynthesis for up to 8 h. The dominating features of phosphorus starvation, were loss of phosphorus and coions from polyphosphate bodies, accumulation of starch, decrease in the volume density of ribosomes both in the chloroplast and cytoplasm, and an increase in wall thickness. Under conditions favoring photosynthesis the mass fraction for phosphorus is low after 1 h, exceptionally high by 2 h, and diminishes by 8 h. High amounts of phosphorus are also regained under conditions favoring glycolysis and photophosphorylation but not respiration. After 2 h under photosynthetic conditions the volume densities of the chloroplast, cytoplasmic ribosomes, the vacuole, and the mitochondrion increased over controls. By 8 h the relative volume of the single ramified mitochondrion had decreased slightly and recognizable segments of it were sequestered within the vacuome. The autophagic nature of the vacuole was further evidenced by the presence of ribosomes and whorls of lamellae within it. Serial sections showed that all polyphosphate granules and sequestered materials were located within a continuous vacuolar cisterna.
MICRONUTRIENT UPTAKE AND TRANSLOCATION BY MACROCYSTIS PYRIFERA (PHAEOPHYTA)1
Authors: Manley Steven L. 
Published: November 2004

ABSTRACTRadionuclides of the micronutrients (Mn, Co, Cu, Zn, Mo, and I) of Macrocystis pyrifera (L.) C. Ag. and the nonnutrient Ni were concentrated in sieve tube sap. Micronutrient uptake rates of mature blade tissue were determined using the appropriate radionuclide in artificial seawater. Cellular uptake was distinguished from free space uptake by the use of suitable wash solutions. The uptake rates were then transposed to conditions in the sea, with several assumptions being made. Micronutrient content was determined for mature blade tissue before and after treatment to remove extracellular micronutrients. A mathematical description of frond growth was developed from previously published data and used to derive equations relating micronutrient assimilation (tissue incorporation) and uptake by fronds, both expressed in mg·d−1, to frond length. Calculations revealed that at a certain frond length xi assimilation equaled uptake for Mn, Co, and Fe. Uptake was greater than assimilation for fronds longer than xi and less than assimilation for fronds shorter than xi. This indicated that Mn, Co, and Fe translocation was required from fronds longer than xi to fronds shorter than xi. The large assimilation values at xi for Mn and Co further indicate that these elements, at times, may limit Macrocystis growth. Calculations also showed that Cu, Zn, Mo, I, and Ni uptake was greater than their assimilation for all frond lengths, which suggested that these elements are transported to other tissues for storage (e.g. in holdfast) or release (e.g. from frond apices).
GYMNODINIUM ACIDOTUM NYGAARD (PYRROPHYTA), A DINOFLAGELLATE WITH AN ENDOSYMBIOTIC CRYPTOMONAD1
Authors: Wilcox Lee W. , Wedemayer Gary J. 
Published: November 2004

ABSTRACTUltrastructural examination of the freshwater, blue‐green dinoflagellate Gymnodinium acidotum Nygaard revealed the presence of an endosymbiotic cryptomonad. Features of the endosymbiont allying it with the Cryptophyceae include mitochondria with flattened cristae, paired thylakoids with electron‐dense contents, and nucleomorphs, bodies unique to the Cryptophyceae. This report is the first conclusive documentation of a symbiosis involving these two groups.
RESPONSES OF CERTAIN FRESHWATER PLANKTONIC ALGAE TO FLUORIDE1
Authors: Hekman Wilhelmina E. , Budd Kenneth , Palmer Gerald R. , MacArthur J. Duncan 
Published: November 2004

ABSTRACTThe effects of dissolved fluoride supplied as NaF at up to 150 p.p.m. F− (7.9 mM) on growth, photosynthesis, dark respiration, enolase activity and fluoride uptake were determined for six phytoplankters: Synechococcus leopoliensis (Racib.) Komarek (Cyanophyta), Oscillatoria limnetica Lemmermann (Cyanophyta), Ankistrodesmus braunii Brun (Chlorophyta), Scenedesmus quadricauda (Turp.) Bréb. (Chlorophyta), Cyclotella meneghiniana Kützing (Bacillariophyta) and Stephanodiscus minutus Grun. ex Cleve et Moll (Bacillariophyta). Growth (determined by absorbance at 660 nm or by cell‐numbers) was unaffected by fluoride at up to 50 p.p.m. (2.6 mM) in all algae except S. leopoliensis, in which growth ceased transiently followed by resumption of growth at reduced rate. These effects showed a threshold at ca. 25 p.p.m. (1.3 mM) F− and increased with increasing F− concentration above this threshold. Photosynthetic O2 evolution in the chlorophytes was unaffected by F− at up to 50 p.p.m., whereas in S. leopoliensis F− above ca. 25 p.p.m. caused a concentration‐dependent inhibition of photosynthesis which was most pronounced at saturating irradiance. Dark O2 uptake was unaffected at up to 50 p.p.m. in chlorophytes but was stimulated in S. leopoliensis. Enolase in clarified cell‐extracts of all six algae was inhibited by F−, with Ki values ranging from 27 to 319 μM. Fluorine (measured by proton‐induced gamma‐ray emission) could not be detected in chlorophytes exposed during growth to up to 50 p.p. m. F−, but was detected in S. leopoliensis, O. limnetica and C. meneghiniana. Fluorine associated with cells of these algae increased as the external F− concentration increased.
CARBOXYSOME CONTENT OF SYNECHOCOCCUS LEOPOLIENSIS (CYANOPHYTA) IN RESPONSE TO INORGANIC CARBON1
Authors: Turpin David H. , Miller A. G. , Canvin David T. 
Published: November 2004

ABSTRACTThe carboxysome content of chemostat grown Synechococcus leopoliensis (Racib.) Komarek increases under inorganic carbon limitation. At growth rates of ca. 85%μmax the carboxysome content (±SE) was 0.57 ± 0.09 carboxysomes·cell section−1. Under severe carbon limitation (ca. 13%μmax) this increased to 3.4 · 0.3 carboxysomes·cell section−1. Corresponding to this change is a three order of magnitude decrease in the half‐saturation constant of photosynthesis for dissolved inorganic carbon. Nitrogen and phosphorus limitation had no effect on carboxysome content or the kinetics of photosynthesis with respect to inorganic carbon. These results are discussed in light of the apparent lack of photorespiration in these organisms.
MORPHOLOGICAL VARIABILITY OF EUNOTIA PECTINALIS (BACILLARIOPHYCEAE) IN A SOFTWATER RHODE ISLAND STREAM AND IN CULTURE1
Authors: Steinman Alan D. , Sheath Robert G. 
Published: November 2004

ABSTRACTThe diatom Eunotia pectinalis (O. F. Müll.?) Rabh. exhibited considerable morphological variability in samples collected over a 13‐month period from a softwater Rhode Island stream. All observed morphotypes were classified into three main complexes based upon their valve configuration. These groupings were confirmed by discriminant analysis using quantitative valve characteristics and were named in accordance with their associated varieties: minor (Kütz.) Rabh., pectinalis and ventricosa Grun. Clonal cultures were subjected to a defined series of temperatures, agitation rates and light intensities in order to assess inherent morphological variability. Similar trends were evident for all complexes. Over time, valve length decreased, valve breadth enlarged, and striae number per 10 μm at valve center and apex increased. Morphological plasticity was evident in culture and appeared to be more a function of the clone genotype than the environmental conditions to which it was subjected. One clone originally identified as E. pectinalis var. minor assumed certain morphological features of E. vanheurckii Patr. after four months in culture.
AN ELECTRON MICROSCOPE STUDY OF GAMETE RELEASE AND SETTLING IN THE COMPLANATE FORM OF SCYTOSIPHON (SCYTOSIPHONACEAE, PHAEOPHYTA)1
Authors: Clayton Margaret N. 
Published: November 2004

ABSTRACTThis paper describes the ultrastructural characteristics of gametes and their liberation from the gametangia in Scytosiphon sp., a brown alga showing only slight sexual differentiation. Both male and female gametes are released initially into a central cavity which forms in the gametangial sorus by the extensive dissolution of the internal cell walls. Scytosiphon sp. gametes possess structural features in common with the zoids of other species of brown algae. Gamete fine structure is discussed in relation to cell function. After release from the gametangial sorus, female gametes can be distinguished from males by the presence of a large number of Golgi‐derived vesicles with electron dense cores. It is possible that these vesicles contain the sex attractant compound. When gametes settle they become spherical, the flagella and eyespot are withdrawn into the cell and adhesive material, apparently originating from the activity of the Golgi body, appears on the surface of the cell.
GROWTH RESPONSE OF A NITROGEN FIXER (ANABAENA FLOS‐AQUAE, CYANOPHYCEAE) TO LOW NITRATE1
Authors: Elder Robert G. , Parker Michael 
Published: November 2004

ABSTRACT Anabaena flos‐aquae (Lyngb.) Bréb. was grown in varying concentrations of nitrate. Specific growth rates, as estimated in batch culture, were constant and approached the maximum rate at all concentrations of NO3−‐N tested bewteen 0 and 400 μ/L. Steady‐state biomass, as determined in semicontinuous culture, did not vary with NO3− at slower dilution rates. However at a faster dilution rate, significantly less biomass occurred in intermediate concentrations of NO3− than in either higher or lower concentrations. The results indicate that both growth rate and standing crop are maximized by either N2 fixation or NO3− assimilation, but extracellular NO3− reduces the rate of N2 fixation. Consequently, at very low NO3− concentrations, growth is virtually maximized by N2 fixation alone, and at high concentrations of NO3−, N2 fixation is inhibited but growth is maximized by assimilation of NO3−. At intermediate concentrations of NO3−, growth becomes a function of NO3− assimilation augmented by N2 fixation. In this case, full growth potential is realized only if hydraulic residence time is sufficiently long to compensate for the reduced rate of N2 fixation. Growth rate and standing crop are not diminished in response to the large amount of energy allocated to N2 fixation. Instead, other cellular processes are probably affected negatively during N2 fixation.
CYTOLOGY AND ULTRASTRUCTURE OF CHLORARACHNION REPTANS (CHLORARACHNIOPHYTA DIVISIO NOVA, CHLORARACHNIOPHYCEAE CLASSIS NOVA)1
Authors: Hibberd David J. , Norris Richard E. 
Published: November 2004

ABSTRACTThe green amoeboid cells of Chlorarachnion reptans Geitler are completely naked and each contains a central nucleus, several bilobed chloroplasts each with a central projecting pyrenoid enveloped by a capping vesicle, several Golgi bodies, mitochondria with tubular cristae, extensive rough ER, and a distinct layer of peripheral vesicles. Complex extrusome‐like organelles occur rarely in both the amoeboid and flagellate stages. The only organelles entering the reticulopodia are mitochondria, but microtubules are also present. The chloroplasts contain chlorophylls a and b, but histochemical tests suggest that the carbohydrate storage product probably is not a starch. The chloroplast lamellae are composed of one to three thylakoids or form deep stacks. A girdle lamella and interlamellar partitions are absent. Each chloroplast is bounded by either four separate membranes, a pair of membranes with vesicular profiles between them, or three membranes; all three arrangements may occur in the same chloroplast. A periplastidal compartment occurs near the base of the pyrenoid where there are always four surrounding membranes. The compartment has a relatively dense matrix and contains ribosome‐like particles and small dense spheres; it extends over and into a deep invagination in the pyrenoid where its contents are enclosed in a double‐membraned envelope which is penetrated by wide pores. The zoospores are ovoid and each bears a single laterally inserted flagellum which appears to be wrapped helically around the cell body during swimming. The flagellum lies in a groove in the cell surface and bears fine lateral hairs. Neither a second flagellum or vestige of one, nor an eyespot, is present. A single microtubular root and a larger homogeneous root run from the flagellar base parallel to the emerging flagellum, between the nuclear envelope and the plasmalemma. In the simple flagellar transition region, fine filaments connect adjacent axonemal doublets. A detailed comparison of C. reptans with all other algal taxa results in the conclusion that it must be segregated in the new class Chlorarachniophyceae, the only class in the new division Chlorarachniophyta. The possibility that C. reptans evolved from a symbiosis between a colorless amoeboid cell and a chlorophyll b‐ containing eukaryote is considered, but the possible affinities of the symbiont remain enigmatic. The implications of the unique chloroplast structure of C. reptans for current hypotheses concerning the origin of chloroplasts are discussed.
OBSERVATIONS ON THE LIFE HISTORY OF PAPENFUSSIELLA CALLITRICHA (PHAEOPHYCEAE, CHORDARIALES) IN CULTURE1
Authors: Peters Akira F. 
Published: November 2004

ABSTRACTPapenfussiella callitricha (Rosenv.) Kylin from eastern Canada was studied in culture. Zoids from unilocular sporangia develop into microscopic, filamentous, dioecious gametophytes which produce isogametes in filament cells and few‐chambered plurilocular gametangia. Unfused gametes germinate to reproduce the gametophytes. Fusion takes place between a settled (“female”) and a motile (“male”) gamete. The zygote gives rise to a filamentous plethysmothallus that reproduces asexually by zoids formed in thallus cells and in few‐chambered plurilocular zoidangia. Erect macrothalli are produced on the plethysmothallus, beginning with the formation of upright filaments. Later on, these filaments become the terminal assimilators of the macrothalli. Further assimilatory filaments, rhizoids, and unilocular sporangia are produced in a branching region at the base of the terminal assimilator. Zoids from unilocular sporangia formed in culture germinate to reestablish the gametophyte phase. Chromosome counts yielded n = 19 ± 3 for the gametophytes, and 32 ± 6 for the sporophyte, both plethysmothallus and macrothallus.
LYSIS OFMICROCYSTIS AERUGINOSA(KÜTZ.) BYBDELLOVIBRIO‐LIKE BACTERIA1
Authors: Caiola Maria Grilli , Pellegrini Stefania 
Published: November 2004

ABSTRACTCells ofMicrocystis aeruginosa(Kützing), collected from water‐blooms of Lake Varese, were lysed byBdellovibrio‐like bacteria. The cells were lysed only after penetration. The cyanobacteria and lysing bacteria were characterized by a fibrous glycocalyx. Once the host cell was penetrated, the bacteria remained localized mainly between the host cell wall and cytoplasmic membrane, which appeared partially thickened. Cell lysis began by breakdown of cell structures. The cell wall appeared broken at many sites, and in completely lysed cells, was partially interrupted. The lysis ofMicrocystisby bacteria could be one of the causes of the death of algal blooms.
PERIPHYTON COLONIZATION OF ROCK SURFACES IN A BOREAL FOREST STREAM STUDIED BY SCANNING ELECTRON MICROSCOPY AND TRACK AUTORADIOGRAPHY1
Authors: Hamilton Paul B. , Duthie Hamish C. 
Published: November 2004

ABSTRACTPeriphyton colonization of natural rock surfaces and granite tiles was followed experimentally in the Matamek River, an acidic (pH 5.5) sixth order boreal stream in northeast Quebec, Canada. Accumulation of chlorophyll a and freshweight algal biomass was logarithmic over a 25 day colonization period. The major colonizers were Tabellaria flocculosa (Roth) Kütz., T. fenestrata (Lyngb.) Kütz., Mougeotia sp., and Eunotia pectinalis (Kütz) Rabh., and its varieties. The microcolonization sequence on granite tiles, followed over 27 days with scanning electron microscopy, showed an initial accumulation of algal cells on the upstream and downstream margins and in depressions, followed by a gradual filling‐in of the flat surfaces. It is hypothesized that the observed slow rate of colonization was due to the high surface tension of the granite substratum and the absence of preconditioning by an organic film. It is further hypothesized that the increase in cellular carbon fixation rates of T. flocculosa measured over a 23 day period using nuclear track autoradiography parallels the development of an algal‐detrital microcosm on the granite tile, and is evidence for the establishment of localized tight nutrient spiralling. It is suggested that the periphyton community may be regarded as a nutrient recycling system at a microenvironmental level which may be especially important in oligotrophic systems.