bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon Status Constrains Light Acclimation in the Cyanobacterium Synechococcus elongatus
Authors: MacKenzie Tyler D.B. , Burns Robert A. , Campbell Douglas A. 
Published: October 2004

Abstract
Acclimation to one environmental factor may constrain acclimation to another. Synechococcus elongatus (sp. PCC7942), growing under continuous light in high inorganic carbon (Ci; approximately 4 mm) and low-Ci (approximately 0.02 mm) media, achieve similar photosynthetic and growth rates under continuous low or high light. During acclimation from low to high light, however, high-Ci cells exploit the light increase by accelerating their growth rate, while low-Ci cells maintain the prelight shift growth rate for many hours, despite increased photosynthesis under the higher light. Under increased light, high-Ci cells reorganize their photosynthetic apparatus by shrinking the PSII pool and increasing Rubisco pool size, thus decreasing the photosynthetic source-to-sink ratio. Low-Ci cells also decrease their reductant source-to-sink ratio to a similar level as the high-Ci cells, but do so only by increasing their Rubisco pool. Low-Ci cells thus invest more photosynthetic reductant into maintaining their larger photosystem pool and increasing their Rubisco pool at the expense of population growth than do high-Ci cells. In nature, light varies widely over minutes to hours and is ultimately limited by daylength. Photosynthetic acclimation in S. elongatus occurs in both high and low Ci, but low-Ci cells require more time to achieve acclimation. Cells that can tolerate low Ci do so at the expense of slower photosynthetic acclimation. Such differences in rates of acclimation relative to rates of change in environmental parameters are important for predicting community productivity under variable environments.
The Roles of Ethylene, Auxin, Abscisic Acid, and Gibberellin in the Hyponastic Growth of Submerged Rumex palustris Petioles
Authors: Cox Marjolein C.H. , Benschop Joris J. , Vreeburg Robert A.M. , Wagemaker Cornelis A.M. , Moritz Thomas , Peeters Anton J.M. , Voesenek Laurentius A.C.J. 
Published: October 2004

Abstract
Rumex palustris responds to complete submergence with upward movement of the younger petioles. This so-called hyponastic response, in combination with stimulated petiole elongation, brings the leaf blade above the water surface and restores contact with the atmosphere. We made a detailed study of this differential growth process, encompassing the complete range of the known signal transduction pathway: from the cellular localization of differential growth, to the hormonal regulation, and the possible involvement of a cell wall loosening protein (expansin) as a downstream target. We show that hyponastic growth is caused by differential cell elongation across the petiole base, with cells on the abaxial (lower) surface elongating faster than cells on the adaxial (upper) surface. Pharmacological studies and endogenous hormone measurements revealed that ethylene, auxin, abscisic acid (ABA), and gibberellin regulate different and sometimes overlapping stages of hyponastic growth. Initiation of hyponastic growth and (maintenance of) the maximum petiole angle are regulated by ethylene, ABA, and auxin, whereas the speed of the response is influenced by ethylene, ABA, and gibberellin. We found that a submergence-induced differential redistribution of endogenous indole-3-acetic acid in the petiole base could play a role in maintenance of the response, but not in the onset of hyponastic growth. Since submergence does not induce a differential expression of expansins across the petiole base, it is unlikely that this cell wall loosening protein is the downstream target for the hormones that regulate the differential cell elongation leading to submergence-induced hyponastic growth in R. palustris.
Unique and Overlapping Expression Patterns among the Arabidopsis 1-Amino-Cyclopropane-1-Carboxylate Synthase Gene Family Members
Authors: Tsuchisaka Atsunari , Theologis Athanasios 
Published: October 2004

Abstract
1-Aminocyclopropane-1-carboxylate synthase (ACS) catalyzes the rate-limiting step in the ethylene biosynthetic pathway in plants. The Arabidopsis genome encodes nine ACS polypeptides that form eight functional (ACS2, ACS4-9, and ACS11) homodimers and one nonfunctional (ACS1) homodimer. Transgenic Arabidopsis lines were constructed expressing the β-glucuronidase (GUS) and green fluorescence protein (GFP) reporter genes from the promoter of each of the gene family members to determine their patterns of expression during plant development. All genes, except ACS9, are expressed in 5-d-old etiolated or light-grown seedlings yielding distinct patterns of GUS staining. ACS9 expression is detected later in development. Unique and overlapping expression patterns were detected for all the family members in various organs of adult plants. ACS11 is uniquely expressed in the trichomes of sepals and ACS1 in the replum. Overlapping expression was observed in hypocotyl, roots, various parts of the flower (sepals, pedicle, style, etc.) and in the stigmatic and abscission zones of the silique. Exogenous indole-3-acetic acid (IAA) enhances the constitutive expression of ACS2, 4, 5, 6, 7, 8, and 11 in the root. Wounding of hypocotyl tissue inhibits the constitutive expression of ACS1 and ACS5 and induces the expression of ACS2, 4, 6, 7, 8, and 11. Inducers of ethylene production such as cold, heat, anaerobiosis, and Li+ ions enhance or suppress the expression of various members of the gene family in the root of light-grown seedlings. Examination of GUS expression in transverse sections of cotyledons reveals that all ACS genes, except ACS9, are expressed in the epidermis cell layer, guard cells, and vascular tissue. Similar analysis with root tip tissue treated with IAA reveals unique and overlapping expression patterns in the various cell types of the lateral root cap, cell division, and cell expansion zones. IAA inducibility is gene-specific and cell type-dependent across the root tip zone. This limited comparative exploration of ACS gene family expression reveals constitutive spatial and temporal expression patterns of all gene family members throughout the growth period examined. The unique and overlapping gene activity pattern detected reveals a combinatorial code of spatio-temporal coexpression among the various gene family members during plant development. This raises the prospect that functional ACS heterodimers may be formed in planta.
Airborne Ethylene May Alter Antioxidant Protection and Reduce Tolerance of Holm Oak to Heat and Drought Stress
Authors: Munné-Bosch Sergi , Peñuelas Josep , Asensio Dolores , Llusià Joan 
Published: October 2004

Abstract
Plant-emitted ethylene has received considerable attention as a stress hormone and is considered to play a major role at low concentrations in the tolerance of several species to biotic and abiotic stresses. However, airborne ethylene at high concentrations, such as those found in polluted areas (20–100 nL L−1) for several days, has received far less attention in studies of plant stress tolerance, though it has been shown to alter photosynthesis and reproductive stages (seed germination, flowering, and fruit ripening) in some species. To assess the potential effects of airborne ethylene on plant stress tolerance in polluted areas, the extent of oxidative stress, photo- and antioxidant protection, and visual leaf area damage were evaluated in ethylene-treated (approximately 100 nL L−1 in air) and control (without ethylene fumigation) holm oak (Quercus ilex) plants exposed to heat stress or to a combination of heat and drought stress. Control plants displayed tolerance to temperatures as high as 50°C, which might be attributed, at least in part, to enhanced xanthophyll de-epoxidation and 2-fold increases in α-tocopherol, and they suffered oxidative stress only when water deficit was superimposed on temperatures above 45°C. By contrast, ethylene-treated plants showed symptoms of oxidative stress at lower temperatures (35°C) than the controls in drought, as indicated by enhanced malondialdehyde levels, lower α-tocopherol and ascorbate concentrations, and a shift of the redox state of ascorbate to its oxidized form. In addition, ethylene-treated plants showed higher visual leaf area damage and greater reductions in the maximum efficiency of the PSII photochemistry than controls in response to heat stress or to a combination of heat and drought stress. These results demonstrate for the first time that airborne ethylene at concentrations similar to those found in polluted areas may reduce plant stress tolerance by altering, among other possible mechanisms, antioxidant defenses.
Quantification of Compartmented Metabolic Fluxes in Developing Soybean Embryos by Employing Biosynthetically Directed Fractional 13C Labeling, Two-Dimensional [13C, 1H] Nuclear Magnetic Resonance, and Comprehensive Isotopomer Balancing
Authors: Sriram Ganesh , Fulton D. Bruce , Iyer Vidya V. , Peterson Joan Marie , Zhou Ruilian , Westgate Mark E. , Spalding Martin H. , Shanks Jacqueline V. 
Published: October 2004

Abstract
Metabolic flux quantification in plants is instrumental in the detailed understanding of metabolism but is difficult to perform on a systemic level. Toward this aim, we report the development and application of a computer-aided metabolic flux analysis tool that enables the concurrent evaluation of fluxes in several primary metabolic pathways. Labeling experiments were performed by feeding a mixture of U-13C Suc, naturally abundant Suc, and Gln to developing soybean (Glycine max) embryos. Two-dimensional [13C, 1H] NMR spectra of seed storage protein and starch hydrolysates were acquired and yielded a labeling data set consisting of 155 13C isotopomer abundances. We developed a computer program to automatically calculate fluxes from this data. This program accepts a user-defined metabolic network model and incorporates recent mathematical advances toward accurate and efficient flux evaluation. Fluxes were calculated and statistical analysis was performed to obtain sds. A high flux was found through the oxidative pentose phosphate pathway (19.99 ± 4.39 μmol d−1 cotyledon−1, or 104.2 carbon mol ± 23.0 carbon mol per 100 carbon mol of Suc uptake). Separate transketolase and transaldolase fluxes could be distinguished in the plastid and the cytosol, and those in the plastid were found to be at least 6-fold higher. The backflux from triose to hexose phosphate was also found to be substantial in the plastid (21.72 ± 5.00 μmol d−1 cotyledon−1, or 113.2 carbon mol ±26.0 carbon mol per 100 carbon mol of Suc uptake). Forward and backward directions of anaplerotic fluxes could be distinguished. The glyoxylate shunt flux was found to be negligible. Such a generic flux analysis tool can serve as a quantitative tool for metabolic studies and phenotype comparisons and can be extended to other plant systems.
Recurrent preeclampsia and perinatal outcome: a study of women with recurrent preeclampsia compared with women with preeclampsia who remained normotensive during their prior pregnancies
Authors: Mendilcioglu Inanc , Trak Bilal , Uner Mine , Umit Selda , Kucukosmanoglu Mesut 
Published: October 2004

Objective.  To evaluate the impact of preeclampsia recurrence on perinatal outcome.Materials and methods.  A case‐controlled study was performed in multiparous women who developed preeclampsia in index pregnancy (n = 64). Among these, women who had preeclampsia in previous pregnancies (n = 21) were compared to those who remained normotensive during their prior pregnancies (n = 43). Maternal and fetal variables were compared. Multivariate logistic analyses were performed to examine the impact of preeclampsia recurrence on fetal loss, preterm delivery, small for gestational age (SGA) occurrence and respiratory distress syndrome adjusted for confounding variables.Results.  No statistical significant difference was observed between the two groups in terms of age, delivery weeks, steroid use and laboratory markers. Fetal loss was higher in women with recurrent preeclampsia (19.0%) than in women with preeclampsia who had a normotensive pregnancy history (4.7%), with adjusted odds ratio (OR) of 5.77 [95% confidence interval (CI) 0.84–39.54].Conclusion.  Women with recurrent preeclampsia had a higher rate of perinatal loss compared to women with preeclampsia who were normotensive in their prior pregnancies.
Neonatal outcome in a Danish national cohort of 8602 children born after in vitro fertilization or intracytoplasmic sperm injection: the role of twin pregnancy
Authors: Pinborg Anja , Loft Anne , Andersen Anders Nyboe 
Published: October 2004

Background.  In Denmark, 4% of all infants are born after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) and 40% of these children are twins.Methods.  We investigated neonatal outcome in a complete Danish IVF/ICSI birth cohort including 8602 infants born between 1995 and 2000: 3438 twins (40%) and 5164 singletons (60%). Births conceived after IVF or ICSI were identified by record linkage with the Danish IVF Registry and the National Medical Birth Registry. Data on neonatal outcome were collected from the National Patient Registry.Results.  IVF/ICSI twins had a 10‐fold increased age‐ and parity‐adjusted risk of delivery before 37 completed weeks [odds ratio (OR) 9.9, 95% confidence interval (95% CI) 8.7–11.3] and a 7.4‐fold increased risk of delivery before 32 completed weeks (OR 7.4, 95% CI 5.6–9.8) compared with singletons. Correspondingly, ORs of birthweight <2500 g and birthweight <1500 g in twins were 11.8 (95% CI 10.3–13.6) and 5.4 (95% CI 4.1–7.0), respectively. The stillbirth rate was doubled in twins (13.1/1000) compared with singletons (6.6/1000) (p = 0.002). The risk of cesarean section and of admittance to a neonatal intensive care unit (NICU) was 4.6‐ and 1.8‐fold higher in IVF/ICSI twins than in singletons. The rate of major malformations was 40.4/1000 in twins and 36.8/1000 in singletons (p = 0.4), whereas the total malformation rate (major + minor) was higher in twins (73.7/1000) than in singletons (55.0/1000) (p = 0.001). After exclusion of patent ductus arteriosus (PDA), which is strongly associated with preterm birth, no significant differences in any malformation rates were observed between twins and singletons. Apart from the frequency of ICSI children with hypospadias, which reached a significance level of p = 0.05, malformation rates in ICSI children were similar to those in IVF children.Conclusions.  This study indicates that neonatal outcome in IVF/ICSI twins is considerably poorer than in singletons. Thus, the impact is to draw the attention of clinicians to the benefit of elective single embryo transfer (eSET).
Management of ovarian cysts
Authors: Knudsen Ulla Breth , Tabor Ann , Mosgaard Berit , Andersen Erik Soegaard , Kjer Jens Joergen , Hahn‐Pedersen Suzanne , Toftager‐Larsen Kim , Mogensen Ole 
Published: October 2004

Background.  The treatment of an ovarian cyst relies on its nature, and accurate preoperative discrimination of benign and malignant cysts is therefore of crucial importance. This study was undertaken to review the literature concerning the preoperative diagnosis and treatment of ovarian cysts.Methods.  Articles concerning ovarian cysts from a medline literature search during the period 1985–2003 were included in addition to articles found as references in the initial publications.Results.  Different methods for discriminating between benign and malignant ovarian cysts are discussed. The diagnosis and the treatment are assessed in relation to age, menopausal status, pregnancy, and whether the cyst is presumed to be benign or malignant. In general, expectant management is the choice in premenopausal and pregnant women with non‐suspicious cysts and normal levels of CA‐125. In postmenopausal women, unilocular, anechoic cysts less than 5 cm in diameter together with a normal CA‐125 may be followed up. Operation is recommended in women with cysts larger than 5 cm and/or elevated levels of CA‐125. Women with symptoms should be operated regardless of age, menopausal status, or ultrasound findings.Conclusions.  The preoperative discrimination between benign and malignant ovarian cysts is a challenge. Multimodal methods improve the results of single modalities, but we still need improved preoperative diagnostic tools. Furthermore, these methods should be validated in consecutive patient populations large enough to give a reliable estimate of the method's sensitivity and specificity.
Perinatal outcome of twin pregnancies after in vitro fertilization
Authors: Manoura Antonia , Korakaki Eftyhia , Hatzidaki Eleftheria , Bikouvarakis Stylianos , Papageorgiou Maria , Giannakopoulou Christine 
Published: October 2004

Background.  There are conflicting data concerning perinatal outcome of twin, in vitro fertilization (IVF) pregnancies. The aim of this study was to evaluate and compare perinatal and neonatal outcomes in twin IVF pregnancies to those of spontaneously conceived twin gestations.Methods.  The medical files of 73 IVF and 148 naturally conceived twin pregnancies were studied retrospectively. Data concerning maternal characteristics, obstetric complications, and neonatal outcome were recorded and compared by χ2 test. The one‐way analysis of variance (anova) was used to compare the means of groups.Results.  Mean maternal age, the proportion of nulliparous women, and the incidence of premature rupture of membranes, cesarean section, and premature delivery were significantly higher in the study group. The mean birthweight was significantly lower, the frequency of admission to the intensive care unit and the duration of hospitalization were significantly higher in the study group. The incidence of intaventricular hemorrhage was significantly higher in the IVF group. The number of perinatal deaths was similar.Conclusion.  IVF twin pregnancies are at greater risk for obstetric complications and adverse neonatal outcome in comparison with naturally conceived twin gestations.
AKINETE GERMINATION IN ANABAENA CIRCINALIS (CYANOPHTA)
Authors: van Dok Wendy , Hart Barry T. 
Published: October 2004

ABSTRACT Akinetes of a clonal culture of Anabaena circinalis Rabenhorst from Mt. Bold reservoir (eutrophic), South Australia, were isolated and the effects of light, phosphorus, and nitrogen availability on their germination were investigated. Light was required but there was no significant difference in percentage of germination after 72 h if akinetes were incubated in ASM‐1 medium at irradiances of 15, 30, or 50 μmol.m‐2.s‐1. Maximum akinete germination occurred by 48 h. Nitrogen was not required, as 88% of akinetes germinated in the flasks without combined nitrogen added to the medium and without N2 in the air. NH4+‐N at 28 mg N.L‐1 completely suppressed germination, whereas 28 mg NO3 N.L‐1 had no effect relative to the controls without nitrogen. Phosphorus was required, and at 48 h percentage of germination in the flasks with 0.6 mg P.L‐1 added (78%) was significantly greater than in the flasks with 0.06 P.L‐1 (58%) and 0 mgP.L‐1 (24%) added. Germlings in the 0 mg P.L‐1 flasks were only 2–4 cells long and stunted in appearance, whereas germlings at all other P concentrations were 8–16 cells long. It is likely that the isolation process exposed some akinetes to intracellular phosphorus released from lysing vegetative cells, but this was insufficient to allow normal development in the 0 mg P.L‐1 flasks. The plot of percentage of germination vs. initial phosphorus concentration, in the medium showed a relationship analogous to Michaelis‐Menten nutrient uptake kinetics, suggesting that a specific membrane‐bound enzyme system(s) is involved, with phosphorus as the substrate. The half saturation value (KS) for germination was 50 μg P.L‐1.
LIGHT‐DEPENDENT GROWTH, DARK SURVIVAL, AND GLUCOSE UPTAKE BY CRYPTOPHYTES ISOLATED FROM A FRESHWATER CHEMOCLINE
Authors: Gervais Frank 
Published: October 2004

ABSTRACT Clones of Cryptomonas phaseolus Skuja, Cryptomonas rostratiformis (Skuja) Skuja in Huber‐Pestalozi, and Cryptomonas undulata Gervais were isolated from the deep chlorophyll maximum near the oxic/anoxic boundary layer of the mesoeutrophic lake Schlachtensee, Germany. Different autecological features of these species were studied in batch culture experiments. Cryptomonas cf. ovata Ehrenberg and Chroomonas sp. that never dominated in the deep chlorophyll layer were also isolated from Schlachtensee to study their light‐dependent growth in comparison to the deep‐living species. Cryptomonas undulata, C. cf. ovata, and C. phaseolus had a very low light compensation point (5–7 μmol.m‐2.s‐1),whereas the growth rate of Chroomonas sp. and C. rostratiformis was positive above 16 and 24 μmol.m‐2.s‐1. Cryptomonas phaseclus and Chroomonas sp. became photoinhibited above photon flux densities of 92 and 116 μmol.m‐2.s‐1. Cryptomonas rostratiformis, C. cf. ovata, and C. undulata reached a maximum growth rate at a considerably higher photon flux density (198–250 μmol.m‐2.s‐1). Cryptomonas phaseolus grew fastest under light‐limiting conditions. Chyptomonas phaseolus and C. undulata were best able to suruive prolonged periods of darkness. Cryptomonas phaseolus, C. rostratiformis, and C. undulata did not show any uptake of fluorescent latex beads. When labeled glucose was provided in naturally occurring concentrations, carbon uptake by C. phaseolus, C. rostratiformis, and C. undulata was negligibly small in comparison to cellular carbon content. I suggest that the adaptation to a low‐light environment is an important preadaptation for the dominance of C. phaseolus and C. undulata near the freshwater chemocline.
INTRASPECIFIC VARIATION IN THE DINOFLAGELLATEGAMBIERDIZSCUS TOXICUS(DINOPHYCEAE). I. ISOZYME ANALYSIS
Authors: Chinain Mireille , Germain Michel , Sako Yoshihiko , Pauillac Serge , Legrand Anne‐Marie 
Published: October 2004

ABSTRACTIntraspecific variation among 19 isolates of the ciguatera‐causing dinoflagellateGambierdiscus toxicusAdachi & Fukuyo (Dinophyceae) collected from French Polynesia, New Caledonia, and the French West Indies was investigated by isozyme analysis. Comparison of their cell sizes and growth rates revealed that significant variation exists among these clones. Comparison of electrophoretic patterns for seven enzyme systems indicated thatG. toxicusis comprised of numerous biochemically distinct strains. Isolates from Tubuai and Hao appeared to be the most distantly related. Tahitian strains ofG. toxicusalso showed a remarkably low degree of similarity with the Tubuai isolates. The latter, which were taken from the same locale in Tubuai, also exhibited highly heterogeneous electrophoretic Profiles when compared to each other, suggesting a multiclonal origin. The single isolate analyzed from the Atlantic Ocean was most closely related to Tahitian isolates, despite their geographic separation. Finally, no clear relationship was found between the electrophoretic profiles of these isolates and their capacity to produce ciguatoxic compounds.