bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poplar Peroxiredoxin Q. A Thioredoxin-Linked Chloroplast Antioxidant Functional in Pathogen Defense
Authors: Rouhier Nicolas , Gelhaye Eric , Gualberto Jose M. , Jordy Marie-Noelle , De Fay Elisabeth , Hirasawa Masakazu , Duplessis Sebastien , Lemaire Stephane D. , Frey Pascal , Martin Francis , Manieri Wanda , Knaff David B. , Jacquot Jean-Pierre 
Published: March 2004

AbstractPeroxiredoxins are ubiquitous thioredoxin- or glutaredoxin-dependent peroxidases, the function of which is to destroy peroxides. Peroxiredoxin Q, one of the four plant subtypes, is a homolog of the bacterial bacterioferritin comigratory proteins. We show here that the poplar (Populus tremula x Populus tremuloides) protein acts as a monomer with an intramolecular disulfide bridge between two conserved cysteines. A wide range of electron donors and substrates was tested. Unlike type II peroxiredoxin, peroxiredoxin Q cannot use the glutaredoxin or cyclophilin isoforms tested, but various cytosolic, chloroplastic, and mitochondrial thioredoxins are efficient electron donors with no marked specificities. The redox midpoint potential of the peroxiredoxin Q catalytic disulfide is -325 mV at pH 7.0, explaining why the wild-type protein is reduced by thioredoxin but not by glutaredoxin. Additional evidence that thioredoxin serves as a donor comes from the formation of heterodimers between peroxiredoxin Q and monocysteinic mutants of spinach (Spinacia oleracea) thioredoxin m. Peroxiredoxin Q can reduce various alkyl hydroperoxides, but with a better efficiency for cumene hydroperoxide than hydrogen peroxide and tertiary butyl hydroperoxide. The use of immunolocalization and of a green fluorescence protein fusion construct indicates that the transit sequence efficiently targets peroxiredoxin Q to the chloroplasts and especially to those of the guard cells. The expression of this protein and of type II peroxiredoxin is modified in response to an infection by two races of Melampsora larici-populina, the causative agent of the poplar rust. In the case of an hypersensitive response, the peroxiredoxin expression increased, whereas it decreased during a compatible interaction.
Production of Reactive Oxygen Species, Alteration of Cytosolic Ascorbate Peroxidase, and Impairment of Mitochondrial Metabolism Are Early Events in Heat Shock-Induced Programmed Cell Death in Tobacco Bright-Yellow 2 Cells
Authors: Vacca Rosa Anna , de Pinto Maria Concetta , Valenti Daniela , Passarella Salvatore , Marra Ersilia , De Gara Laura 
Published: March 2004

Abstract
To gain some insight into the mechanisms by which plant cells die as a result of abiotic stress, we exposed tobacco (Nicotiana tabacum) Bright-Yellow 2 cells to heat shock and investigated cell survival as a function of time after heat shock induction. Heat treatment at 55°C triggered processes leading to programmed cell death (PCD) that was complete after 72 h. In the early phase, cells undergoing PCD showed an immediate burst in hydrogen peroxide (H2O2) and superoxide (O2 ·-) anion production. Consistently, death was prevented by the antioxidants ascorbate (ASC) and superoxide dismutase (SOD). Actinomycin D and cycloheximide, inhibitors of transcription and translation, respectively, also prevented cell death, but with a lower efficiency. Induction of PCD resulted in gradual oxidation of endogenous ASC; this was accompanied by a decrease in both the amount and the specific activity of the cytosolic ASC peroxidase (cAPX). A reduction in cAPX gene expression was also found in the late PCD phase. Moreover, changes of cAPX kinetic properties were found in PCD cells. Production of ROS in PCD cells was accompanied by early inhibition of glucose (Glc) oxidation, with a strong impairment of mitochondrial function as shown by an increase in cellular NAD(P)H fluorescence, and by failure of mitochondria isolated from cells undergoing PCD to generate membrane potential and to oxidize succinate in a manner controlled by ADP. Thus, we propose that in the early phase of tobacco Bright-Yellow 2 cell PCD, ROS production occurs, perhaps because of damage of the cell antioxidant system, with impairment of the mitochondrial oxidative phosphorylation.
A Novel Endo-β-Mannanase Gene in Tomato LeMAN5 Is Associated with Anther and Pollen Development
Authors: Filichkin Sergei A. , Leonard Jeffrey M. , Monteros Alvaro , Liu Po-Pu , Nonogaki Hiroyuki 
Published: March 2004

Abstract
Endo-β-mannanase (EC 3.2.1.78) is involved in cell wall disassembly and the weakening of plant tissues by degrading mannan polymers in the cell walls. Endo-β-mannanase genes are expressed in tomato (Lycopersicon esculentum) seeds (LeMAN1 and LeMAN2) and fruits (LeMAN3 and LeMAN4). A novel endo-β-mannanase gene (termed LeMAN5) was found in the tomato genome by genome-walking PCR and bacterial artificial chromosome library screening. The 5′-upstream region of this endo-β-mannanase gene contained four copies of the pollen-specific cis-acting elements POLLEN1LELAT52 (AGAAA). A GUS-reporter gene driven with the putative LeMAN5 promoter (-543 to +38) was activated in anthers and pollen of transgenic Arabidopsis, with the highest β-glucuronidase activity detected in pollen. β-Glucuronidase expression was detected in mature pollen retained in sporangia, discharged pollen, and elongating pollen tubes in transgenic Arabidopsis. Consistently, expression of LeMAN5 mRNA and endo-β-mannnanase activity was detected in tomato anthers and pollen. In anthers, the highest mRNA expression and endo-β-mannanase activity were detected during late stages of anther development, when pollen maturation occurred. Endo-β-mannanase activity was present in discharged pollen, which was easily eluted in a buffer, indicating that the enzyme proteins are probably secreted from, and deposited on, the surface of pollen. These data suggest that the LeMAN5 endo-β-mannanase is associated with anther and pollen development.
Molecular Analysis of 10 Coding Regions from Arabidopsis That Are Homologous to the MUR3 Xyloglucan Galactosyltransferase
Authors: Li Xuemei , Cordero Israel , Caplan Jeffrey , Mølhøj Michael , Reiter Wolf-Dieter 
Published: March 2004

Abstract
Plant cell walls are composed of a large number of complex polysaccharides, which contain at least 13 different monosaccharides in a multitude of linkages. This structural complexity of cell wall components is paralleled by a large number of predicted glycosyltransferases in plant genomes, which can be grouped into several distinct families based on conserved sequence motifs (B. Henrissat, G.J. Davies [2000] Plant Physiol 124: 1515-1519). Despite the wealth of genomic information in Arabidopsis and several crop plants, the biochemical functions of these coding regions have only been established in a few cases. To lay the foundation for the genetic and biochemical characterization of putative glycosyltransferase genes, we conducted a phylogenetic and expression analysis on 10 predicted coding regions (AtGT11-20) that are closely related to the MUR3 xyloglucan galactosyltransferase of Arabidopsis. All of these proteins contain the conserved sequence motif pfam 03016 that is the hallmark of the β-d-glucuronosyltransferase domain of exostosins, a class of animal enzymes involved in the biosynthesis of the extracellular polysaccharide heparan sulfate. Reverse transcriptase-polymerase chain reaction and promoter:β-glucuronidase studies indicate that all AtGT genes are transcribed. Although six of the 10 AtGT genes were expressed in all major plant organs, the remaining four genes showed more restricted expression patterns that were either confined to specific organs or to highly specialized cell types such as hydathodes or pollen grains. T-DNA insertion mutants in AtGT13 and AtGT18 displayed reductions in the Gal content of total cell wall material, suggesting that the disrupted genes encode galactosyltransferases in plant cell wall synthesis.
Geminating Pollen Has Tubular Vacuoles, Displays Highly Dynamic Vacuole Biogenesis, and Requires VACUOLESS1 for Proper Function
Authors: Hicks Glenn R. , Rojo Enrique , Hong Seho , Carter David G. , Raikhel Natasha V. 
Published: March 2004

Abstract
Vacuoles perform multiple functions in plants, and VCL1 (VACUOLESS1) is essential for biogenesis with loss of expression in the vcl1 mutant leading to lethality. Vacuole biogenesis plays a prominent role in gametophytes, yet is poorly understood. Given the importance of VCL1, we asked if it contributes to vacuole biogenesis during pollen germination. To address this question, it was essential to first understand the dynamics of vacuoles. A tonoplast marker, δ-TIP::GFP, under a pollen-specific promoter permitted the examination of vacuole morphology in germinating pollen of Arabidopsis. Our results demonstrate that germination involves a complex, yet definable, progression of vacuole biogenesis. Pollen vacuoles are extremely dynamic with remarkable features such as elongated (tubular) vacuoles and highly mobile cytoplasmic invaginations. Surprisingly, vcl1 did not adversely impact vacuole morphology in pollen germinated in vitro. To focus further on VCL1 in pollen, reciprocal backcrosses demonstrated reduced transmission of vcl1 through male gametophytes, indicating that vcl1 was expressive after germination. Interestingly, vcl1 affected the fertility of female gametophytes that undergo similarly complex vacuole biogenesis. Our results indicate that vcl1 is lethal in the sporophyte but is not fully expressive in the gametophytes. They also point to the complexity of pollen vacuoles and suggest that the mechanism of vacuole biogenesis in pollen may differ from that in other plant tissues.
Palaeoecology of a post‐extinction reef: Famennian (Late Devonian) of the Canning Basin, north‐western Australia
Authors: Wood Rachel 
Published: March 2004

Reefs were decimated by the Frasnian/Famennian (Late Devonian) mass extinction event (371 Ma), and are assumed to have survived only as depauperate calcimicrobial communities dominated by disaster taxa. Description of Famennian proximal reef‐slope communities within the Windjana Limestone, Canning Basin, north‐western Australia, shows that, notwithstanding the loss of large metazoans, novel ecologies were established in this setting by a rich biota of survivor and progenitor taxa. Diverse calcimicrobes together with algae, crinoids, bryozoans, brachiopods, and abundant sponges (stromatoporoids, inozoans, sphinctozoans, lithistids and hexactinellids) formed a reef framework of either elevated platy structures up to 4 m in diameter and 0.35 m thick, or mounds up to 15 m in diameter. This framework was dominated by a complex intergrowth of calcimicrobes, where Rothpletzella formed the primary framework, Ortonella, and Girvanella were secondary encrusters, and Shuguria spp. occupied small crypts 2–30 mm in diameter. Contiguous columnar stromatolites up to 50 mm in height and 1 m in width grew upwards from substrate sheltered beneath large sheltered primary cavities: based on minimum growth rates of 50–100 μm/year these are estimated to have been between 500 and 1000 years old. The elevated platy community is inferred to have grown in conditions of episodic siliciclastic sediment input; the reef mounds grew during either episodes, or in localised areas, of low sedimentation. At least 14 morphospecies of spicular sponges are now identified from the Windjana Limestone, where only two were previously documented. These fore‐slope reef communities exposed in Windjana Gorge flourished in high‐energy carbonate environments dominated by coated grain sediments, and where rapid, early lithification was pervasive.Such observations demonstrate that no protracted interval of time was necessarily required for post‐extinction ‘recovery’ in regions where some reef‐building taxa survived and suitable carbonate habitats persisted or returned. Moreover, they show that new ecologies, rather than remnants of the pre‐extinction community, could be established rapidly. The reef‐slope communities of the Windjana Limestone offer little evidence to support the ideas of resurgence or invasion of taxa from deeper waters after the Frasnian/Famennian extinction. Indeed, there is evidence to suggest that similar microbial‐sponge communities were already established in margin and reef slope communities in the latest Frasnian. As such, the most dramatic ecological changes caused by the extinction occurred in back‐reef communities.
Skeletal muscle HSP72 response to mechanical unloading: influence of endurance training
Authors: Desplanches D. , Ecochard L. , Sempore B. , Mayet‐Sornay M.‐H. , Favier R. 
Published: March 2004

AbstractAims:  It has been shown that increased contractile activity results in heat shock protein 72 (HSP72) accumulation in various skeletal muscles. By contrast, there is no consensus for muscle HSP72 response to muscle disuse for short duration (5–8 days). On the basis of a greater constitutive HSP72 expression in slow‐twitch muscles we tested the hypothesis that mechanical unloading for a longer period (2 weeks) would affect this phenotype to a greater extent. Secondly, we evaluated the effects of a physiological muscle heat shock protein (HSP) enhancer (endurance training) on HSP response to unloading and muscle remodelling.Methods:  Adult male Wistar rats were assigned randomly to four groups: (1) sedentary weight‐bearing; (2) hindlimb‐unloaded (HU) via tail suspension for 2 week; (3) trained on a treadmill (6 week) and (4) trained 6 week and then HU for 2 week.Results:  Unloading resulted in a preferential atrophy of slow muscles [soleus (SOL), adductor longus (AL)] and a slow‐to‐fast fibre transition with no change in HSP72 level. HSP72 levels were significantly lower in fast muscles [extensor digitorum longus (EDL) and plantaris (PLA)], and did not change with mechanical unloading. Endurance training was accompanied by a small (SOL) or a large (EDL, PLA) increase in HSP72 level with no change in AL. Training‐induced accumulation of HSP72 disappeared with subsequent unloading in the SOL and PLA whereas HSP72 content remained elevated in EDL.Conclusion:  The results of this study indicate that (1) after 2 weeks of unloading no change occurred in HSP72 protein levels of slow‐twitch muscles despite a slow‐to‐fast fibre transition; and (2) the training‐induced increase of HSP72 content in skeletal muscles did not attenuate fibre transition.
Human skeletal muscle cell differentiation is associated with changes in myogenic markers and enhanced insulin‐mediated MAPK and PKB phosphorylation
Authors: Al‐Khalili L. , Krämer D. , Wretenberg P. , Krook A. 
Published: March 2004

AbstractAim:  We hypothesized that myogenic differentiation of HSMC would yield a more insulin responsive phenotype.Methods:  We assessed expression of several proteins involved in insulin action or myogenesis during differentiation of primary human skeletal muscle cultures (HSMC).Results:  Differentiation increased creatine kinase activity and expression of desmin and myocyte enhancer factor (MEF)2C. No change in expression was observed for big mitogen‐activated protein kinase (BMK1/ERK5), MEF2A, insulin receptor (IR), hexokinase II, and IR substrates 1 and 2, while expression of glycogen synthase, extracellular signal‐regulated kinase 1 and 2 (ERK1/2 MAP kinase) and the insulin responsive aminopeptidase increased after differentiation. In contrast to protein kinase B (PKB)a, expression of (PKB)b increased, with differentiation. Both basal and insulin‐stimulated PI 3‐kinase activity increased with differentiation. Insulin‐mediated phosphorylation of PKB and ERK1/2 MAP kinase increased after differentiation.Conclusion:  Components of the insulin‐signalling machinery are expressed in myoblast and myotube HSMC; however, insulin responsiveness to PKB and ERK MAP kinase phosphorylation increases with differentiation.
Global, synchronous oscillations in cytosolic calcium and adherence in bradykinin‐stimulated Madin‐Darby canine kidney cells
Authors: De Blasio B. F. , Røttingen J.‐A. , Sand K. L. , Giaever I. , Iversen J.‐G. 
Published: March 2004

AbstractAims and Methods:  Intercellular Ca2+ oscillations are a universal mode of signalling in both excitable and non‐excitable cells. Here, we study the relationship between Ca2+ signalling and coherent changes in adhesion properties by measuring the transepithelial impedance across bradykinin‐stimulated Madin‐Darby canine kidney (MDCK) cell layers grown on a microelectrode. During hormone stimulation, the impedance is found to oscillate, reflecting that the cells undergo morphological/adhesive alterations with high spatio‐temporal organization. The experiments are supplemented with parallel, digital imaging fluorescence microscopy of bradykinin‐induced single‐cell Ca2+ oscillations.Results:  In agreement with previous experiments, MDCK cells are found to elicit synchronous, multicellular Ca2+ oscillations in response to hormone stimulus. The periods of the Ca2+ oscillations and the electrical fluctuations are found to coincide. Further, blocking of gap junctions by 18α‐glycyrrhetinic acid causes a loss of synchrony in Ca2+ signals and inhibition of impedance oscillations, emphasizing the importance of gap junctions in the signal transduction process.Conclusion:  Based on these observations it is concluded that the co‐ordinated adhesive changes in MDCK cells are a direct consequence of synchronized Ca2+ oscillations.Calcium signalling represents an efficient way of organizing physiological responses in a tissue. A possible functional implication of the structural changes might be to modulate transportation of various substances across the cell sheet.
Serum insulin‐like growth factor‐I concentrations in late middle age: no association with birthweight in three UK cohorts
Authors: Holt R. I. G. , Syddall H. E. , Phillips D. I. W. , Martyn C. N. , Gluckman P. D. , Breier B. H. , Wood P. J. , Fall C. H. D. 
Published: March 2004

AbstractBackground:  Small body size at birth and during infancy is associated with an increased risk of adult osteoporosis and cardiovascular disease. Fetal programming of the growth hormone–insulin‐like growth factor (GH‐IGF) axis may provide a mechanism for these epidemiological findings.Aims:  To determine whether measurements of GH and IGF‐I in late middle age were related to size at birth and in infancy.Methods:  Overnight urinary GH excretion and fasting serum IGF‐I were measured in 309 men and 193 women from Hertfordshire (born 1920–1930) for whom birthweight and weight at 1 year were recorded. Serum IGF‐I was measured in men and women from Preston (n = 254, born 1935–1943) and Sheffield (n = 215, born 1939–1940) whose birthweight and other birth measurements were recorded.Results:  Urinary GH and serum IGF‐I were not related to birthweight, other measurements at birth, or weight at 1 year.Conclusion:  In contrast to previous studies in children or young adults, these data do not support the hypothesis that IGF‐I concentrations are programmed by intra‐uterine events, as assessed by birthweight, in late middle age.
Interstitial glycerol concentrations in human skeletal muscle and adipose tissue during graded exercise
Authors: Stallknecht B. , Kiens B. , Helge J. W. , Richter E. A. , Galbo H. 
Published: March 2004

AbstractAim:  It is not clear how lipolysis changes in skeletal muscle and adipose tissue during exercise of different intensities. We aimed at estimating this by microdialysis and muscle biopsy techniques.Methods:  Nine healthy, young men were kicking with both legs at 25% of maximal power (Wmax) for 45 min and then simultaneously with one leg at 65% and the other leg at 85%Wmax for 35 min.Results:  Glycerol concentrations in skeletal muscle and adipose tissue interstitial fluid and in arterial plasma increased (P < 0.001) during low intensity exercise and increased (P < 0.05) even more during moderate intensity exercise. The difference between interstitial muscle and arterial plasma water glycerol concentration, which indicates the direction of the glycerol flux, was positive (P < 0.05) at rest (21 ± 9 μm) and during exercise at 25%Wmax (18 ± 6 μm). The difference decreased (P < 0.05) with increasing exercise intensity and was not significantly different from zero during exercise at 65% (−11 ± 17 μM) and 85% (−12 ± 13 μm) Wmax. In adipose tissue, the difference between interstitial and arterial plasma water glycerol increased (P < 0.001) with increasing intensity. The net triacylglycerol breakdown, measured chemically from the biopsy, did not differ significantly from zero at any exercise intensity although directional changes were similar to microdialysis changes.Conclusions:  Skeletal muscle releases glycerol at rest and at low exercise intensity but not at higher intensities. This can be interpreted as skeletal muscle lipolysis peaking at low exercise intensities but could also indicate that glycerol is taken up in skeletal muscle at a rate which is increasing with exercise intensity.
Genetic diversity and differentiation in Portuguese cattle breeds using microsatellites
Authors: Mateus J. C. , Penedo M. C. T. , Alves V. C. , Ramos M. , Rangel‐Figueiredo T. 
Published: March 2004

SummaryGenotype data from 30 microsatellites were used to assess genetic diversity and relationships among 10 native Portuguese cattle breeds, American Charolais and the Brazilian Caracú. Hardy–Weinberg equilibrium was observed for all loci/population combinations except for five loci in Brava de Lide and one locus in Alentejana that exhibited heterozygote deficiency. Estimates of average observed and expected heterozygosities, total number of alleles (TNA) per breed and mean number of alleles (MNA) per locus/population were obtained. A total of 390 alleles were detected. TNA among Iberian cattle ranged from 170 to 237 and MNA ranged from 5.67 to 8.07. The highest observed heterozygosities were found in the Caracú, Maronesa, Garvonesa and Arouquesa and the lowest in Brava de Lide and Mirandesa. Estimation of population subdivision using Wright's FST index showed that the average proportion of genetic variation explained by breed differences was 9%. Neighbour‐joining phylogenetic trees based on DA distances showed that the genetic relationships of present‐day Portuguese native breeds are consistent with historical origins in the Brown Concave (Arouquesa, Mirandesa, Marinhoa) and Red Convex (Mertolenga, Alentejana, Garvonesa, Minhota) evolutionary groups. The Iberian Black Orthoide group, represented by Brava de Lide and Maronesa, and the Barrosã breed appeared to be more closely related to the Brown Concave group but may represent a separate lineage. The Caracú breed was not found to be closely associated with any of the native Portuguese breeds.
Native antiviral specificity of chicken Mx protein depends on amino acid variation at position 631
Authors: Ko J. H. , Takada A. , Mitsuhashi T. , Agui T. , Watanabe T. 
Published: March 2004

SummaryAn attempt was made to determine whether amino acid variation at position 631 in the chicken Mx protein definitely influences antiviral specificity, using an artificial mutation technique by which a single amino acid was reciprocally substituted between Ser (AGT) and Asn (AAT) at position 631 of the negative and positive chicken Mx, respectively. Using permanently transfected 3T3 cell lines, the antiviral potential of chicken Mx against vesicular stomatitis virus infection was analysed. The results indicated that the phenotype of antiviral activity depends on the amino acid difference at position 631; that is, the genotype coding Asn at position 631 corresponds to the positive antiviral phenotype, and the genotype coding Ser corresponds to the negative phenotype. The present study has confirmed that the antiviral specificity of chicken Mx protein is determined by an amino acid substitution at the carboxy terminus.