bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genital herpes infection in pregnancy
Authors: Brocklehurst Peter 
Published: July 2002

Genital herpes infection remains a difficult problem to manage during pregnancy. The natural history of the infection during pregnancy is not well understood and potential management strategies remain unevaluated. For example the risk of mother-to-child transmission in women with recurrent genital herpes lesions at the time of vaginal delivery is still unknown. We do not know whether delivery by caesarean section decreases this risk and yet it is the most widely used intervention in this situation. We are only just beginning to understand the epidemiology of asymptomatic infection and the risk that asymptomatic viral shedding may pose to the newborn. In addition, new methods of diagnosis and new strategies for management are regularly being proposed with little formal evaluation of their effectiveness in the clinical setting.This article aims to review current knowledge applicable to the clinical situation and suggest how our knowledge and management of this problem may be improved in the future.
Viability of the southern elephant seal population of the Falkland Islands
Authors: Galimberti F. , Sanvito S. , Boitani L. , Fabiani A. 
Published: July 2002

AbstractAccurate long‐term series of demographic data are available for most populations of southern elephant seals. However, research on the elephant seals of the Falkland Islands began only recently, and information for an accurate forecasting of the future of this population is lacking. In this paper we present data on the current status of the population and its trend in size during the last 11 years. We built an age‐structured model of the population and analyzed the effect of variation in demographic parameters on population growth. Elasticity analysis demonstrated that variation in mortality has a more pronounced effect on instantaneous growth rate than an equivalent variation in fecundity. We examined the effects of environmental variability, inbreeding and catastrophes on population viability by a computer simulation using the VORTEX PVA programme. In the stochastic model, the most important factor affecting extinction risk was variability in mortality rates, in particular of the adult classes. We concluded that, although the population does not appear to be at immediate risk of extinction, its small size and isolation make it necessary to accurately monitor the population trends and to acquire additional information on life history and feeding strategies.
Structure-Function Analysis of Nod Factor-Induced Root Hair Calcium Spiking in Rhizobium-Legume Symbiosis
Authors: Wais Rebecca J. , Keating David H. , Long Sharon R. 
Published: July 2002

Abstract
In the Rhizobium-legume symbiosis, compatible bacteria and host plants interact through an exchange of signals: Host compounds promote the expression of bacterial biosynthetic nod(nodulation) genes leading to the production of a lipochito-oligosaccharide signal, the Nod factor (NF). The particular array of nod genes carried by a given species ofRhizobium determines the NF structure synthesized and defines the range of legume hosts by which the bacterium is recognized. Purified NF can induce early host responses even in the absence of live Rhizobium One of the earliest known host responses to NF is an oscillatory behavior of cytoplasmic calcium, or calcium spiking, in root hair cells, initially observed in Medicago spp. and subsequently characterized in four other genera (D.W. Ehrhardt, R. Wais, S.R. Long [1996] Cell 85: 673–681; S.A. Walker, V. Viprey, J.A. Downie [2000] Proc Natl Acad Sci USA 97: 13413–13418; D.W. Ehrhardt, J.A. Downie, J. Harris, R.J. Wais, and S.R. Long, unpublished data). We sought to determine whether live Rhizobium trigger a rapid calcium spiking response and whether this response is NF dependent. We show that, in the Sinorhizobium meliloti-Medicago truncatula interaction, bacteria elicit a calcium spiking response that is indistinguishable from the response to purified NF. We determine that calcium spiking is a nod gene-dependent host response. Studies of calcium spiking in M. truncatula and alfalfa (Medicago sativa) also uncovered the possibility of differences in early NF signal transduction. We further demonstrate the sufficiency of thenod genes for inducing calcium spiking by usingEscherichia coli BL21 (DE3) engineered to express 11S. meliloti nod genes.
Biochemical and Molecular Inhibition of Plastidial Carbonic Anhydrase Reduces the Incorporation of Acetate into Lipids in Cotton Embryos and Tobacco Cell Suspensions and Leaves
Authors: Hoang Chau V. , Chapman Kent D. 
Published: July 2002

Abstract
Two cDNAs encoding functional carbonic anhydrase (CA) enzymes were recently isolated from a non-photosynthetic, cotyledon library of cotton (Gossypium hirsutum) seedlings with putative plastid-targeting sequences (GenBank accession nos. AF132854 andAF132855). Relative CA transcript abundance and enzyme activity increased 9 and 15 times, respectively, in cotton embryos during the maximum period of reserve oil accumulation. Specific sulfonamide inhibitors of CA activity significantly reduced the rate of [14C]acetate incorporation into total lipids in cotton embryos in vivo, and in embryo plastids in vitro, suggesting a role for CA in plastid lipid biosynthesis. CA inhibitors did not affect acetyl-coenzyme A carboxylase activity or total storage protein synthesis. Similar results were obtained for two other plant systems: cell suspensions (and isolated plastids therefrom) of tobacco (Nicotiana tabacum), and chloroplasts isolated from leaves of transgenic CA antisense-suppressed tobacco plants (5% of wild-type CA activity). In addition, tobacco cell suspensions treated with the CA inhibitor ethoxyzolamide showed a substantial loss of CO2 compared with controls. The rate of [14C]acetate incorporation into lipid in cell suspensions was reduced by limiting external [CO2] (scrubbed air), and this rate was further reduced in the presence of ethoxyzolamide. Together, these results indicate that a reduction of CA activity (biochemical or molecular inhibition) impacts the rate of plant lipid biosynthesis from acetate, perhaps by impairing the ability of CA to efficiently “trap” inorganic carbon inside plastids for utilization by acetyl-coenzyme A carboxylase and the fatty acid synthesis machinery.
Sugar Accumulation in Grape Berries (Cloning of Two Putative Vacuolar Invertase cDNAs and Their Expression in Grapevine Tissues)
Authors: Davies C. , Robinson S. P. 
Published: July 2002

Abstract
During grape berry (Vitis vinifera L.) ripening, sucrose transported from the leaves is accumulated in the berry vacuoles as glucose and fructose. To study the involvement of invertase in grape berry ripening, we have cloned two cDNAs (GIN1 and GIN2) from berries. The cDNAs encode translation products that are 62% identical to each other and both appear to be vacuolar forms of invertase. Both genes are expressed in a variety of tissues, including berries, leaves, roots, seeds, and flowers, but the two genes have distinct patterns of expression. In grape berries, hexose accumulation began 8 weeks postflowering and continued until the fruit was ripe at 16 weeks. Invertase activity increased from flowering, was maximal 8 weeks postflowering, and remained constant on a per berry basis throughout ripening. Expression of GIN1 and GIN2 in berries, which was high early in berry development, declined greatly at the commencement of hexose accumulation. The results suggest that although vacuolar invertases are involved in hexose accumulation in grape berries, the expression of the genes and the synthesis of the enzymes precedes the onset of hexose accumulation by some weeks, so other mechanisms must be involved in regulating this process.
The Promoter for Tomato 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Gene 2 Has Unusual Regulatory Elements That Direct High-Level Expression
Authors: Daraselia N. D. , Tarchevskaya S. , Narita J. O. 
Published: July 2002

Abstract
The promoter region of tomato (Lycopersicon esculentum) 3-hydroxy-3-methylglutaryl coenzyme A reductase gene 2 (HMG2) has been analyzed using the transient expression of HMG2-luciferase fusions in red fruit pericarp. The mRNA for HMG2 accumulates to high levels during fruit ripening, in a pattern that coincides with the synthesis of the carotenoid lycopene. Unlike most promoters, the region that is upstream of the HMG2 TATA element is not required for high-level expression. The 180-bp region containing the TATA element, the 5[prime] untranslated region, and the translation start site are comparable in strength to the full-length 35S cauliflower mosaic virus promoter. Pyrimidine-rich sequences present in the 5[prime] untranslated leader are important in regulating expression. Also, the ATG start region has been found to increase translation efficiency by a factor of 4 to 10. An alternative hairpin secondary structure has been identified surrounding the HMG2 initiator ATG, which could participate in the translational regulation of this locus. HMG2 appears to be a novel class of strong plant promoters that incorporate unusual, positive regulators of gene expression.
Adenosine-5[prime]-Phosphate Deaminase (A Novel Herbicide Target)
Authors: Dancer J. E. , Hughes R. G. , Lindell S. D. 
Published: July 2002

Abstract
The isolation of carbocyclic coformycin as the herbicidally active component from a fermentation of Saccharothrix species was described previously (B.D. Bush, C.V. Fitchett, D.A. Gates, D. Langley [1993] Phytochemistry 32: 737–739). Here we report that the primary mode of action of carbocyclic coformycin has been identified as inhibition of the enzyme AMP deaminase (EC 3.5.4.6) following phosphorylation at the 5[prime] hydroxyl on the carbocyclic ring in vivo. When pea (Pisum sativum L. var Onward) seedlings are treated with carbocyclic coformycin, there is a very rapid and dramatic increase in ATP levels, indicating a perturbation in purine metabolism. Investigation of the enzymes of purine metabolism showed a decrease in the extractable activity of AMP deaminase that correlates with a strong, noncovalent association of the phosphorylated natural product with the protein. The 5[prime]-phosphate analog of the carbocyclic coformycin was synthesized and shown to be a potent, tight binding inhibitor of AMP deaminase isolated from pea seedlings. Through the use of a synthetic radiolabeled marker, rapid conversion of carbocyclic coformycin to the 5[prime]-phosphate analog could be demonstrated in vivo. It is proposed that inhibition of AMP deaminase leads to the death of the plant through perturbation of the intracellular ATP pool.
The massugu1 Mutation of Arabidopsis Identified with Failure of Auxin-Induced Growth Curvature of Hypocotyl Confers Auxin Insensitivity to Hypocotyl and Leaf
Authors: Watahiki M. K. , Yamamoto K. T. 
Published: July 2002

Abstract
Unilateral application of indole-3-acetic acid (IAA) in a lanolin base to hypocotyls of partially etiolated seedlings of wild-type Arabidopsis thaliana induced growth curvature in a dose-dependent manner. The effects of IAA in concentrations from 1 to 1000 [mu]M were studied, with maximum IAA-induced curvature at 100 [mu]M. Three IAA-insensitive mutants were isolated and are all in the same locus, massugu1 (msg1). They did not undergo hypocotyl growth curvature at any of the IAA concentrations tested. msg1 is recessive and is located on chromosome 5. msg1 hypocotyl growth is resistant to 2,4-dichlorophenoxyacetic acid (2,4-D), but the roots are as sensitive to 2,4-D as the wild type. Growth of the hypocotyl was inhibited to essentially the same extent as the wild type by 6-benzylaminopurine, abscisic acid, and l-aminocyclopropane-1-carboxylate, an ethylene precursor. The msg1 leaves were also resistant to 2,4-D-induced chlorosis. The gravitropic response of the msg1 hypocotyl takes much more time to initiate and achieve the wild-type degree of curvature, whereas the msg1 roots responded normally to gravity. The mature plants and the etiolated seedlings of msg1 were generally wild type in appearance, except that their rosette leaves were either epinastic or hyponastic. msg1 is the first auxin-insensitive mutant in which its effects are mostly restricted to the hypocotyl and leaf, and msg1 also appears to be auxin specific.
The Correlation of Profiles of Surface pH and Elongation Growth in Maize Roots
Authors: Peters Winfried S. , Felle Hubert H. 
Published: July 2002

Abstract
High-resolution profiles of surface pH and growth along vertically growing maize (Zea mays) primary root tips were determined simultaneously by pH-sensitive microelectrodes and marking experiments. Methodological tests were carried out that proved the reliability of our kinematic growth analysis, while questioning the validity of an alternative technique employed previously. A distal acidic zone around the meristematic region and a proximal one around the elongation zone proper were detected. This pattern as such persisted irrespective of the bulk pH value. The proximal acidic region coincided with maximum relative elemental growth rates (REGR), and both characters reacted in a correlated manner to auxin and cyanide. The distal acidic band was unrelated to growth, but was abolished by cyanide treatment. We conclude that: (a) the pattern of surface pH as such is a regulated feature of growing root tips; (b) the correlation of extracellular pH and growth rate suggests a functional relationship only along proximal portions of the growing root tip; and (c) the distal acidic band is not caused by pH buffering by root cap mucilage, as suggested previously, but rather is controlled by cellular activity.
Increasing Tryptophan Synthesis in a Forage LegumeAstragalus sinicusby Expressing the Tobacco Feedback-Insensitive Anthranilate Synthase (ASA2) Gene
Authors: Cho Hyeon-Je , Brotherton Jeffrey E. , Song Hee-Sook , Widholm Jack M. 
Published: July 2002

AbstractA cDNA clone that encodes a feedback-insensitive anthranilate synthase (AS), ASA2, isolated from a 5-methyl-tryptophan (Trp) (5MT)-resistant tobacco cell line under the control of the constitutive cauliflower mosaic virus 35S promoter, was introduced into the forage legume Astragalus sinicus byAgrobacterium rhizogenes with kanamycin selection. The 35S-ASA2 gene was expressed constitutively as demonstrated by northern-blot hybridization analyses and the presence of feedback-insensitive AS. Hairy root lines transformed with 35S-ASA2 grew in concentrations of up to 100 μm 5MT, whereas the controls were completely inhibited by 15 μm 5MT. Expression of the feedback-insensitive ASA2 resulted in a 1.3- to 5.5-fold increase in free Trp. Kinetic studies of the AS activity demonstrate the Trp feedback alterations and indicate that the ASA2 α-subunit can interact with the native A. sinicus β-subunit to form an active enzyme. TheASA2 transcript and high free Trp were also detected in the leaves, stems, and roots of plants regenerated from the transformed hairy roots. Thus, we show for the first time that ASA2can be used to transform plants of a different species to increase the levels of the essential amino acid Trp and impart 5MT resistance.
Oligoguluronates Elicit an Oxidative Burst in the Brown Algal Kelp Laminaria digitata
Authors: Küpper Frithjof Christian , Kloareg Bernard , Guern Jean , Potin Philippe 
Published: July 2002

Abstract
Oligomeric degradation products of alginate elicited a respiratory and oxidative burst in the sporophytes of the kelp Laminaria digitata. The generation of activated oxygen species (AOS), O2 −, and H2O2 was detected at the single cell level, using nitroblue tetrazolium precipitation and a redox-sensitive fluorescent probe, respectively. The oxidative burst involved diphenyleneiodonium-sensitive AOS-generating machinery and its amplitude depended on the type of tissue. After a first elicitation plants were desensitized for about 3 h. The activity of alginate oligosaccharides was dose dependent, saturating around 40 μm. It was also structure-dependent, with homopolymeric blocks of α-1,4-l-guluronic acid, i.e. the functional analogs of oligogalacturonic blocks in pectins, being the most active signals. The perception of oligoguluronate signals resulted in a strong efflux of potassium. Pharmacological dissection of the early events preceding the emission of AOS indicated that the transduction chain of oligoguluronate signals in L. digitata is likely to feature protein kinases, phospholipase A2, as well as K+, Ca2+, and anion channels.
Evolution of Floral Meristem Identity Genes. Analysis ofLolium temulentum Genes Related to APETALA1 andLEAFY of Arabidopsis
Authors: Gocal Greg F.W. , King Rod W. , Blundell Cheryl A. , Schwartz Owen M. , Andersen Claus H. , Weigel Detlef 
Published: July 2002

Abstract
Flowering (inflorescence formation) of the grass Lolium temulentum is strictly regulated, occurring rapidly on exposure to a single long day (LD). During floral induction, L. temulentum differs significantly from dicot species such as Arabidopsis in the expression, at the shoot apex, of twoAPETALA1 (AP1)-like genes, LtMADS1 andLtMADS2, and of L. temulentum LEAFY(LtLFY). As shown by in situ hybridization,LtMADS1 and LtMADS2 are expressed in the vegetative shoot apical meristem, but expression increases strongly within 30 h of LD floral induction. Later in floral development,LtMADS1 and LtMADS2 are expressed within spikelet and floret meristems and in the glume and lemma primordia. It is interesting that LtLFY is detected quite late (about 12 d after LD induction) within the spikelet meristems, glumes, and lemma primordia. These patterns contrast with Arabidopsis, whereLFY and AP1 are consecutively activated early during flower formation. LtMADS2, when expressed in transgenic Arabidopsis plants under the control of theAP1 promoter, could partially complement the organ number defect of the severe ap1-15 mutant allele, confirming a close relationship between LtMADS2 andAP1.
The Heme-Oxygenase Family Required for Phytochrome Chromophore Biosynthesis Is Necessary for Proper Photomorphogenesis in Higher Plants
Authors: Davis Seth J. , Bhoo Seong Hee , Durski Adam M. , Walker Joseph M. , Vierstra Richard D. 
Published: July 2002

AbstractThe committed step in the biosynthesis of the phytochrome chromophore phytochromobilin involves the oxidative cleavage of heme by a heme oxygenase (HO) to form biliverdin IXα. Through positional cloning of the photomorphogenic mutant hy1, the Arabidopsis HO (designated AtHO1) responsible for much of phytochromobilin synthesis recently was identified. Using theAtHO1 sequence, we identified families ofHO genes in a number of plants that cluster into two subfamilies (HO1- and HO2-like). The tomato (Lycopersicon esculentum) yg-2 andNicotiana plumbaginifolia pew1 photomorphogenic mutants are defective in specific HO genes. Phenotypic analysis of a T-DNA insertion mutant of Arabidopsis HO2 revealed that the second HO subfamily also contributes to phytochromobilin synthesis. Homozygous ho2-1 plants show decreased chlorophyll accumulation, reduced growth rate, accelerated flowering time, and reduced de-etiolation. A mixture of apo- and holo-phyA was detected in etiolated ho2-1 seedlings, suggesting that phytochromobilin is limiting in this mutant, even in the presence of functional AtHO1. The patterns of ArabidopsisHO1 and HO2 expression suggest that the products of both genes overlap temporally and spatially. Taken together, the family of HOs is important for phytochrome-mediated development in a number of plants and that each family member may uniquely contribute to the phytochromobilin pool needed to assemble holo-phytochromes.
Chemical characteristics of dimer interfaces in the legume lectin family
Authors: Elgavish Sharona , Shaanan Boaz 
Published: July 2002

AbstractThe Erythrina corallodendron lectin (EcorL) crystallizes in monoclinic and hexagonal crystal forms. Comparison of the newly determined hexagonal form (PDB code 1fyu) with the monoclinic form shows that the dimeric structure of EcorL reflects the inherent biological structure of the protein and is not an artifact of the crystal packing. To further understand the factors determining the dimerization modes of legume lectins, EcorL, concanavalin A (ConA), and Griffonia simplicifolia (GS4) were taken as representatives of the three unique dimers found in the family. Six virtual homodimers were generated. The hydropathy, amino acid composition, and solvation energy were calculated for all nine homodimers. Each of the three native dimers has a distinct chemical composition. EcorL has a dominant hydrophobic component, and ConA has a strong polar component, but in GS4 the three components contribute equally to the interface. This distribution pattern at the interface is unique to the native dimers and distinct from the partition observed in the virtual dimers. Amino acid composition of other members of the family that dimerize like EcorL or ConA maintain the same pattern of amino acids distribution observed in EcorL and ConA. However, lectins that dimerize like GS4 do not show a particularly distinct distribution. In all cases, the calculated solvation energy of the native dimer was lower than that of the virtual dimers, suggesting that the observed mode of dimerization is the most stable organization for the given sequence and tertiary structure. The dimerization type cannot be predicted by sequence analysis.
Single-Passage Analysis of Unsteady Flows Around Vibrating Blades of
a Transonic Fan Under Inlet Distortion
Authors: Li H. D. , He L. 
Published: July 2002

Abstract
Computations of unsteady flows due to inlet distortion driven blade vibrations, characterized by long circumferential wavelengths, typically need to be carried out in multi-passage/whole-annulus domains. In the present work, a single-passage three-dimensional unsteady Navier-Stokes approach has been developed and applied to unsteady flows around vibrating blades of a transonic fan rotor (NASA Rotor-67) with inlet distortions. The phase-shifted periodic condition is applied using a Fourier series based method, “shape-correction,” which enables a single-passage solution to unsteady flows under influences of multiple disturbances with arbitrary interblade phase angles. The computational study of the transonic fan illustrates that unsteady flow response to an inlet distortion varies greatly depending on its circumferential wavelength. The response to a long wavelength (whole-annulus) distortion is strongly nonlinear with a significant departure of its time-averaged flow from the steady state, while that at a short wavelength (two passages) behaves largely in a linear manner. Nevertheless, unsteady pressures due to blade vibration, though noticeably different under different inlet distortions, show a linear behavior. Thus, the nonlinearity of the flow response to inlet distortion appears to influence the aerodynamic damping predominantly by means of changing the time-averaged flow. Good agreements between single-passage solutions and multi-passage solutions are obtained for all the conditions considered, which clearly demonstrates the validity of the phase-shifted periodicity at a transonic nonlinear distorted flow condition. For the present cases, typical CPU time saving by a factor of 5–10 is achieved by the single-passage solutions.
Effects of Vapor Superheat and Condensate Subcooling on Laminar Film Condensation
Authors: Mitrovic J. 
Published: July 2002

AbstractNusselt's model is employed to illustrate the effects of vapor superheat and condensate subcooling on laminar film condensation occurring under simultaneous actions of gravity and interfacial shear. The vapor superheat affects the condensation kinetics in cooperation with heat transfer in both phases. Under comparable conditions, the condensate film is thinner and the heat transfer coefficient larger for superheated than for saturated vapor. The heat flux on the cooling surface arising from the sensible heat of condensate increases as the critical point of the condensing substance is approached and, at this point, the Nusselt condensation model gives the single-phase boundary layer solutions. [S0022-1481(00)00701-5]