bluuebunny/crossref_metadata_2025 huggingface dataset:
LAG‐3 (CD223) reduces macrophage and dendritic cell differentiation from monocyte precursors
Authors: Buisson Sandrine , Triebel Frédéric
Published: February 2005

Major histocompatibility complex (MHC) class II molecules expressed on monocytes may play a role in the control of differentiation of antigen‐presenting cells. A soluble LAG‐3 (CD223) molecule (sLAG‐3) is a natural, high‐affinity ligand for MHC class II. It is known to induce maturation of monocyte‐derived dendritic cells in vitro and is used as a vaccine adjuvant to induce CD4 T helper type 1 responses and CD8 T‐cell responses in vivo. Here, we demonstrate that sLAG‐3 (but not an MHC class II‐specific monoclonal antibody) reduces the differentiation of monocytes into macrophages in the presence of granulocyte–macrophage colony‐stimulating factor (GM‐CSF) as well as their differentiation into dendritic cells in the presence of GM‐CSF and interleukin‐4, as shown by a decrease in CD14 and CD1a expression, respectively. Dendritic cells derived from monocytes in the presence of sLAG‐3 showed impaired antigen‐presentation function, as assessed by the reduced capability to induce proliferation of T cells. Our results suggest that activated LAG‐3+ lymphocytes present at sites of inflammation may reduce the differentiation of monocytes into macrophages or fully competent antigen‐presenting dendritic cells, thus limiting the magnitude of the ongoing T‐cell immune responses.
Hot‐spot mutations in hepatitis B virus core gene: eliciting or evading immune clearance?
Authors: Liu Z. , Luo K. , He H. , Hou J.
Published: February 2005

Summary.  The biological implications of substitutions L60V and I97L in the core (c) gene of hepatitis B virus (HBV) were investigated in order to determine whether they could change the immunogenicity of HBcAg or influence the immune response in mice. Three strains of recombinant adenoviruses – AdHBV‐WT, AdHBV‐L60V and AdHBV‐I97L – containing wild‐type or mutant HBV genomes were constructed using the AdEasy system and used to infect BALB/c mice intranasally. Infected mice produced anti‐HBc efficiently to comparable levels. IgG1 and IgG2a specific for HBcAg were present in mice sera, and the response was dominated by IgG2a. The lymphocyte proliferative response specific for HBcAg was assessed by [3H]‐thymidine uptake. We found that AdHBV‐WT induced a stronger T‐cell proliferation response than AdHBV‐L60V and AdHBV‐I97L. In conclusion, the L60V and I97L substitutions had no influence on humoral immune responses, but could downregulate T‐cell responses to HBcAg, suggesting that L60V and I97L were immune escape mutants.
Treatment of acute hepatitis C infection in HIV‐infected patients: a retrospective analysis of eleven cases
Authors: Vogel M. , Bieniek B. , Jessen H. , Schewe C. K. , Hoffmann C. , Baumgarten A. , Kroidl A. , Bogner J. R. , Spengler U. , Rockstroh J. K.
Published: February 2005

Summary.  Studies on hepatitis C virus (HCV) monoinfected patients suggest high sustained treatment response rates of up to 98% when interferon monotherapy is administered during the acute phase of HCV‐infection. To clarify whether early treatment of acute hepatitis C is similarly efficient in human immunodeficiency virus (HIV) positive patients, we conducted a retrospective survey of HIV‐positive patients with acute HCV infection. Eleven HIV‐positive patients who had been treated with interferon or interferon/ribavirin were identified at eight HIV‐specialty outpatient clinics. The patients had been treated over a median 25 weeks with standard interferon (two patients), pegylated interferon (four patients) and pegylated interferon in combination with ribavirin (five patients). A post‐treatment response (negative serum HCV‐RNA at the end of treatment) was seen in 10 of 11 patients and HCV‐RNA remained undetectable 24 weeks after the end of treatment in all the 10 responders. Alanine aminotransferase (ALT) normalized in eight patients while two virological responders and one nonresponder showed persistent mild ALT elevations. In conclusion, early treatment of acute hepatitis C seems to achieve high sustained virological treatment response rates also in patients with HIV‐infection.
Hepatitis B virus: significance of genotypes
Authors: Schaefer S.
Published: February 2005

Summary. Hepatitis B Virus (HBV) genotypes have come of age. The concept that HBV genotypes may influence the course of disease and relevant biological differences has now been recognised. However, there are still major gaps in our knowledge. Most clinical data come from Asia and describe findings in patients infected with genotypes B and C. Large scale studies with genotypes A and D as found in Europe or A, D and E from Africa are urgently needed to broaden our understanding. Experimental data which explainin vivofindings in terms of differences in molecular biologyin vitroare still in the beginning. The succeeding years will see many interesting studies which will aid our understanding of how variants and genotypes of HBV influence the spectrum of disease in people infected with HBV.
Monitoring of HBeAg levels may help to predict the outcomes of lamivudine therapy for HBeAg positive chronic hepatitis B
Authors: Park N. H. , Shin J. W. , Park J. H. , Bang S‐J. , Kim D‐H. , Joo K. R. , Kim D. H.
Published: February 2005

Summary.  The aim of this study was to determine whether the changing patterns of quantitative hepatitis B e antigen (HBeAg) levels by serial monitoring could predict HBeAg seroconversion and viral breakthrough during lamivudine therapy. We retrospectively analysed 340 HBeAg positive naïve chronic hepatitis B patients treated with lamivudine. The mean duration of lamivudine therapy was 18.7 (range 6–56) months. The changing patterns and reduction rates of pretreatment HBeAg levels by serial monitoring were categorized into three groups: Decrescendo group (n = 195), Decrescendo‐crescendo group (n = 65) and no changing or fluctuating group (n = 80). Of 109 patients who had achieved HBeAg seroconversion, 105 (96.3%) were included in the decrescendo group. The decrescendo group, pretreatment quantitative HBeAg levels, alanine aminotransferase levels, and the duration of lamivudine therapy were independent predictive factors for HBeAg seroconversion. Of 82 patients who had viral breakthrough, 53 (64.6%) were in the decrescendo‐crescendo group and 21 (25.6%) were in the no changing or fluctuating group. The only predictive factor for viral breakthrough was the changing patterns of quantitative HBeAg levels, especially, the decrescendo‐crescendo group and the no changing or fluctuating group. The mean time of turning points in the decrescendo‐crescendo group was 7.1 months earlier than the mean time of viral breakthrough (9.0 months vs 16.5 months). Therefore, the changing patterns of quantitative HBeAg levels by serial monitoring during lamivudine therapy may allow not only the prediction of treatment responses, but also an early recognition of a viral breakthrough.
Iron‐regulated transcription and capsule formation in the fungal pathogen Cryptococcus neoformans
Authors: Lian Tianshun , Simmer Megan I. , D’Souza Cletus A. , Steen Barbara R. , Zuyderduyn Scott D. , Jones Steven J. M. , Marra Marco A. , Kronstad James W.
Published: February 2005

Cryptococcus neoformans is the leading cause of fungal meningitis in humans. Production of a polysaccharide capsule is a key virulence property for the fungus and capsule synthesis is regulated by iron levels. Given that iron acquisition is an important aspect of virulence for many pathogens, we employed serial analysis of gene expression (SAGE) to examine the transcriptome under iron‐limiting and iron‐replete conditions. Initially, we demonstrated by SAGE and Northern analysis that iron limitation results in an elevated transcript level for the CAP60 gene that is required for capsule production. We also identified genes encoding putative components for iron transport and homeostasis, including the FTR1 (iron permease) gene, with higher transcript levels in the low‐iron condition. An FTR1 disruption mutant grows more slowly than wild‐type cells in low‐iron medium, and shows delayed growth and altered capsule regulation in iron‐replete medium. Iron deprivation also resulted in elevated SAGE tags for putative extracellular mannoproteins and the GPI8 gene encoding a glycosylphosphatidylinositol (GPI) transamidase. The GPI8 gene appears to be essential while disruption of the CIG1 gene encoding a mannoprotein resulted in impaired growth in low‐iron medium and altered capsule response to the iron‐replete condition. Additionally, we found that iron‐replete conditions led to elevated transcripts for genes for iron storage, nitrogen metabolism, glycolysis, mitochondrial function, lipid metabolism and calmodulin‐calcineurin signalling. Overall, these studies provide the first view of the C. neoformans transcriptional response to different iron levels.
Bacterial transcription elongation factors: new insights into molecular mechanism of action
Authors: Borukhov Sergei , Lee Jookyung , Laptenko Oleg
Published: February 2005

Like transcription initiation, the elongation and termination stages of transcription cycle serve as important targets for regulatory factors in prokaryotic cells. In this review, we discuss the recent progress in structural and biochemical studies of three evolutionarily conserved elongation factors, GreA, NusA and Mfd. These factors affect RNA polymerase (RNAP) processivity by modulating transcription pausing, arrest, termination or anti‐termination. With structural information now available for RNAP and models of ternary elongation complexes, the interaction between these factors and RNAP can be modelled, and possible molecular mechanisms of their action can be inferred. The models suggest that these factors interact with RNAP at or near its three major, nucleic acid‐binding channels: Mfd near the upstream opening of the primary (DNA‐binding) channel, NusA in the vicinity of both the primary channel and the RNA exit channel, and GreA within the secondary (backtracked RNA‐binding) channel, and support the view that these channels are involved in the maintenance of RNAP processivity.
Identification of amino acid residues of the Agrobacterium tumefaciens quorum‐sensing regulator TraR that are critical for positive control of transcription
Authors: White Catharine E. , Winans Stephen C.
Published: February 2005

The LuxR‐type quorum‐sensing transcription factor TraR regulates replication and conjugal transfer of the tumour‐inducing (Ti) plasmid in the plant pathogen Agrobacterium tumefaciens. TraR is a two‐domain protein with an N‐terminal domain that binds to the quorum‐sensing signal N‐3‐oxooctanoyl‐ l‐homoserine lactone (OOHL) and a C‐terminal domain that binds to specific DNA sequences called tra boxes. TraR–OOHL complexes form homodimers that activate transcription of at least seven promoters on the Ti plasmid. At five promoters, a tra box overlaps the binding site of core RNA polymerase (class II promoters), while in the other two promoters, this site is located farther upstream (class I promoters). In this study, we performed saturating point mutagenesis of the surface residues of the TraR C‐terminal domain. Each mutant was tested for proteolytic stability and transcription activity in vivo, and for DNA binding activity in vitro. Mutants of TraR with single substitutions at positions W184, V187, K189, E193Q, V197 and D217 have wild‐type levels of accumulation and DNA binding, but are defective in transcription of both types of promoters. These residues constitute a patch on the surface of the DNA‐binding domain. We propose that this patch is an activating region that recruits RNA polymerase to TraR‐dependent promoters through direct contact. As residues of this patch are critical for activation at both a class I and a class II promoter, we predict that these residues may contact the C‐terminal domain of the RNA polymerase α‐subunit.
CcpN (YqzB), a novel regulator for CcpA‐independent catabolite repression of Bacillus subtilis gluconeogenic genes
Authors: Servant Pascale , Le Coq Dominique , Aymerich Stéphane
Published: February 2005

In Bacillus subtilis, the NADPH‐dependent glyceraldehyde‐3‐phosphate dehydrogenase (GapB) and the phosphoenolpyruvate carboxykinase (PckA) enzymes are necessary for efficient gluconeogenesis from Krebs cycle intermediates. gapB and pckA transcription is repressed in the presence of glucose but not via CcpA, the major transcriptional regulator for catabolite repression in B. subtilis. A B. subtilis mini‐Tn10 transposant library was screened for clones affected in catabolite repression of gapB. Inactivation of a previously unknown gene, yqzB (renamed ccpN for control catabolite protein of gluconeogenic genes), was found to relieve not only gapB but also pckA transcription from catabolite repression. Purified CcpN specifically bound to the gapB and pckA promoters. ccpN is co‐transcribed constitutively with another unknown gene, yqfL. A yqfL deletion lowers the level of gapB and pckA transcription threefold under both glycolytic and gluconeogenic conditions and a ccpN deletion is epistatic over a yqfL deletion. YqfL is thus a positive regulator of the expression of gapB and pckA, the effect of which is not influenced by the metabolic regime of the cell but appears to be mediated by CcpN. ccpN has homologues in many Firmicutes, but not all, while yqfL homologues are widely distributed in Eubacteria and also present in some plants. In all analysed bacterial genomes, ccpN and yqfL are physically linked together or to putative gluconeogenic genes. CcpN thus orchestrates a novel CcpA‐independent mechanism for catabolite repression of gluconeogenic genes highly conserved in Firmicutes and appears as a functional analogue of FruR in Enterobacteria. The physiological significance of the regulation mediated via the three B. subtilis global transcription regulators, CcpA, CggR and CcpN, is discussed.
Pseudomonas aeruginosa fimL regulates multiple virulence functions by intersecting with Vfr‐modulated pathways
Authors: Whitchurch Cynthia B. , Beatson Scott A. , Comolli James C. , Jakobsen Thania , Sargent Jennifer L. , Bertrand Jacob J. , West Joyce , Klausen Mikkel , Waite Leslie L. , Kang Pil Jung , Tolker‐Nielsen Tim , Mattick John S. , Engel Joanne N.
Published: February 2005

Virulence of Pseudomonas aeruginosa involves the co‐ordinate expression of a range of factors including type IV pili (tfp), the type III secretion system (TTSS) and quorum sensing. Tfp are required for twitching motility, efficient biofilm formation, and for adhesion and type III secretion (TTS)‐mediated damage to mammalian cells. We describe a novel gene (fimL) that is required for tfp biogenesis and function, for TTS and for normal biofilm development in P. aeruginosa. The predicted product of fimL is homologous to the N‐terminal domain of ChpA, except that its putative histidine and threonine phosphotransfer sites have been replaced with glutamine. fimL mutants resemble vfr mutants in many aspects including increased autolysis, reduced levels of surface‐assembled tfp and diminished production of type III secreted effectors. Expression of vfr in trans can complement fimL mutants. vfr transcription and production is reduced in fimL mutants whereas cAMP levels are unaffected. Deletion and insertion mutants of fimL frequently revert to wild‐type phenotypes suggesting that an extragenic suppressor mutation is able to overcome the loss of fimL. vfr transcription and production, as well as cAMP levels, are elevated in these revertants, while Pseudomonas quinolone signal (PQS) production is reduced. These results suggest that the site(s) of spontaneous mutation is in a gene(s) which lies upstream of vfr transcription, cAMP, production, and PQS synthesis. Our studies indicate that Vfr and FimL are components of intersecting pathways that control twitching motility, TTSS and autolysis in P. aeruginosa.
Mapping binding residues in the Plasmodium vivax domain that binds Duffy antigen during red cell invasion
Authors: Hans Dhiraj , Pattnaik Priyabrata , Bhattacharyya Arindam , Shakri Ahmad Rushdi , Yazdani Syed Shams , Sharma Monal , Choe Hyeryun , Farzan Michael , Chitnis Chetan E.
Published: February 2005

Plasmodium vivax depends on interaction with the Duffy antigen/receptor for chemokines (DARC) for invasion of human erythrocytes. The 140 kDa P. vivax Duffy‐binding protein (PvDBP) mediates interaction with DARC. The receptor‐binding domain of PvDBP maps to its N‐terminal, cysteine‐rich region, region II (PvRII), which contains approximately 300 amino acid residues including 12 conserved cysteines. Using surface plasmon resonance, we show that binding of PvRII to DARC is a high‐affinity interaction with a binding constant (KD) of 8.7 nM. The minimal binding domain of PvRII has been previously mapped to a central 170‐amino‐acid stretch that includes cysteines 5–8. Here, we have used site‐directed mutagenesis and quantitative binding assays to map amino acid residues within PvRII that make contact with DARC. Of the seven alanine replacement mutations that had an effect on binding, five were mutations in hydrophobic residues suggesting that hydrophobic interactions play a major role in the interaction of PvDBP with DARC. Genetic diversity studies have shown that six of the seven binding residues identified in PvRII are conserved in P. vivax field isolates, which provides support for their role in interaction with DARC.
Carcinoembryonic antigen‐related cell adhesion molecule (CEACAM)‐binding recombinant polypeptide confers protection against infection by respiratory and urogenital pathogens
Authors: Hill Darryl J. , Edwards Andrew M. , Rowe Helen A. , Virji Mumtaz
Published: February 2005

The human‐specific pathogens Neisseria meningitidis, N. gonorrhoea, Haemophilus influenzae and Moraxella catarrhalis share the property of targeting the carcinoembryonic antigen (CEA)‐related cell adhesion molecules (CEACAMs) expressed on human epithelia. CEACAMs are signalling receptors implicated in cell adhesion and regulation of several physiological functions. Their targeting by pathogens can lead to tissue invasion. Although the CEACAM‐binding ligands of the bacteria are structurally diverse, they target a common site on the receptor. We have generated a recombinant polypeptide that blocks the interactions of the mucosal pathogens with human epithelial cells and antibodies against it inhibit M. catarrhalis interactions with the receptor. As such, it is a potential antimicrobial agent to prevent infection via a strategy unlikely to promote bacterial resistance and a vaccine candidate against M. catarrhalis. In addition, it could serve more widely as a novel research tool and as a potential therapeutic agent in CEACAM‐based physiological disorders.
Comparative genome hybridization reveals widespread aneuploidy in Candida albicans laboratory strains
Authors: Selmecki Anna , Bergmann Sven , Berman Judith
Published: February 2005

Clinical strains of Candida albicans are highly tolerant of aneuploidies and other genome rearrangements. We have used comparative genome hybridization (CGH), in an array format, to analyse the copy number of over 6000 open reading frames (ORFs) in the genomic DNA of C. albicans laboratory strains carrying one (CAI‐4) to three (BWP17) auxotrophies. We find that during disruption of the HIS1 locus all genes telomeric to HIS1 were deleted and telomeric repeats were added to a 9 nt sequence within the transforming DNA. This deletion occurred in ∼10% of transformants analysed and was stably maintained through two additional rounds of transformation and counterselection of the transformation marker. In one example, the deletion was repaired, apparently via break‐induced replication. Furthermore, all CAI‐4 strains tested were trisomic for chromosome 2 although this trisomy appears to be unstable, as it is not detected in strains subsequently derived from CAI‐4. Our data indicate CGH arrays can be used to detect monosomies and trisomies, to predict the sites of chromosome breaks, and to identify chromosomal aberrations that have not been detected with other approaches in C. albicans strains. Furthermore, they highlight the high level of genome instability in C. albicans laboratory strains exposed to the stress of transformation and counterselection on 5‐fluoro‐orotic acid.
Leishmania salvage and remodelling of host sphingolipids in amastigote survival and acidocalcisome biogenesis
Authors: Zhang Kai , Hsu Fong‐Fu , Scott David A. , Docampo Roberto , Turk John , Beverley Stephen M.
Published: February 2005

Sphingolipids (SLs) play essential roles in most eukaryotes, but in the trypanosomatid protozoan Leishmania major their functions differ significantly. Previously we showed that null mutants defective in de novo sphingoid base synthesis (spt2–) lacked SLs but grew well and retained lipid rafts while replicating as promastigotes in vitro. However, they experienced catastrophic defects in membrane trafficking on entry into stationary phase, and failed to differentiate to the infective metacyclic form. Here we showed this mutant retained the ability to enter macrophages silently and inhibit activation, although as expected most parasites were destroyed. However, in mouse infections, after a delay rapidly progressive lesions appeared, and purified amastigotes were fully virulent to macrophages and mice. Mass spectrometry of spt2– amastigote lipids revealed the presence of high levels of parasite‐specific inositol phosphorylceramides (IPCs) not synthesized by the mammalian hosts. Inhibitor studies showed that salvage occurs at the level of complex SLs, suggesting that parasites carry out ‘headgroup’ remodelling. Additionally, we describe a new defect of the spt2– promastigotes involving ‘empty’ acidocalcisomes (ACs), which may point to the origin of this organelle from the lysosome‐related organelle/multivesicular body biogenesis pathway. However, ACs in spt2– amastigotes appeared quantitatively and morphologically normal. Thus salvage of SLs and other molecules by intracellular amastigotes play key roles in AC biogenesis and parasite survival in the host.
Differential binding specificities of oral streptococcal antigen I/II family adhesins for human or bacterial ligands
Authors: Jakubovics Nicholas S. , Strömberg Nicklas , Van Dolleweerd Craig J. , Kelly Charles G. , Jenkinson Howard F.
Published: February 2005

The antigen I/II (AgI/II) family polypeptides, ranging from 1310 to 1653 amino acid (aa) residues, are cell wall anchored adhesins expressed by most indigenous species of oral streptococci. The polypeptides interact with a wide range of host molecules, in particular salivary agglutinin glycoprotein (SAG or gp340), and with ligands on other oral bacteria. To determine the receptor recognition properties of six different AgI/II family polypeptides from strains of Streptococcus gordonii, Streptococcus intermedius and Streptococcus mutans, the genes were cloned and expressed on the surface of the surrogate host Lactococcus lactis. The S. gordonii SspA and SspB polypeptides mediated higher binding levels of L. lactis cells to surface immobilized gp340 than did S. intermedius Pas protein, or S. mutans SpaP or PAc proteins. However, the AgI/II proteins were all similar in their abilities to mediate aggregation of lactococci by fluid phase gp340. The SpaPI polypeptide from S. mutans Ingbritt, which was C‐terminally truncated by approximately 400 aa residues, did not bind gp340. Lactococci expressing AgI/II proteins, including SpaPI, were aggregated by a synthetic 16 aa residue peptide SRCRP2 derived from the aa repeat block sequences within gp340. In coaggregation assays, SspB from S. gordonii was unique in mediating coaggregation with only group A and group E strains of Actinomyces naeslundii. All the other AgI/II polypeptides mediated coaggregation with group C and group D strains of A. naeslundii. Analysis of chimeric protein constructs revealed that coaggregation specificity was determined by sequences within the N‐terminal half of AgI/II protein. A synthetic peptide (20 aa residues), which defines a putative adhesion epitope within the C‐terminal region of polypeptide, inhibited AgI/II‐mediated aggregation by gp340 but did not affect coaggregation with A. naeslundii. These results suggest that different mechanisms operate in interactions of AgI/II family polypeptides with native gp340, gp340 SRCR domain peptide, and A. naeslundii. Specificity of these interactions appears to be determined by discontinuous but interacting regions of the polypeptides, thus providing flexibility in receptor recognition for streptococcal colonization of the human host.
Linking isoprene with plant thermotolerance, antioxidants and monoterpene emissions
Authors: PEÑUELAS J. , LLUSIÀ J. , ASENSIO D. , MUNNÉ‐BOSCH S.
Published: February 2005

The purpose of the present study was to test the possible plant thermotolerance role of isoprene and to study its relationship with non‐enzymatic antioxidants and terpene emissions. The gas exchange, chlorophyll fluorescence, extent of photo‐ and oxidative stress, leaf damage, mechanisms of photo‐ and antioxidant protection, and terpene emission were measured in leaves of Quercus ilex seedlings exposed to a ramp of temperatures of 5 °C steps from 25 to 50 °C growing with and without isoprene (10 µL L−1) fumigation. The results showed that isoprene actually conferred thermotolerance (shifted the decrease of net photosynthetic rates from 35 to 45 °C, increased Fv/Fm at 50 °C from 0.38 to 0.65, and decreased the leaf area damaged from 27 to 15%), that it precluded or delayed the enhancement of the antioxidant non‐enzymatic defence conferred by α‐tocopherol, ascorbic acid or β‐carotene consumption in response to increasing temperatures, and that it decreased by approximately 70% the emissions of monoterpenes at the highest temperatures. This suggests that there are inducible mechanisms triggered by the initial stages of thermal damage that up‐regulate these antioxidant compounds at high temperatures and that these mechanisms are somehow suppressed in the presence of exogenous isoprene, which seems to already exert an antioxidant‐like behaviour.
Adjustment of leaf photosynthesis to shade in a natural canopy: reallocation of nitrogen
Authors: EICHELMANN H. , OJA V. , RASULOV B. , PADU E. , BICHELE I. , PETTAI H. , MÄND P. , KULL O. , LAISK A.
Published: February 2005

The present study was performed to investigate the adjustment of the constituents of the light and dark reactions of photosynthesis to the natural growth irradiance in the leaves of an overstorey species,Betula pendulaRoth, a subcanopy speciesTilia cordataP. Mill., and a herbSolidago virgaureaL. growing in a natural plant community in Järvselja, Estonia. Shoots were collected from the site and properties of individual leaves were measured in a laboratory, by applying a routine of kinetic gas exchange and optical measurements that revealed photosystem II (PSII), photosystem I (PSI), and cytochrome b6f densities per leaf area and the distribution of excitation (or chlorophyll, Chl) between the two photosystems. In parallel, N, Chl and ribulose‐bisphosphate carboxylase‐oxygenase (Rubisco) content was measured from the same leaves. The amount of N in photosynthetic proteins was calculated from the measured contents of the components of the photosynthetic machinery. Non‐photosynthetic N was found as the residual of the budget. Growth in shade resulted in the decrease of leaf dry mass to a half of the DW in sun leaves in each species, but the total variation, from the top to the bottom of the canopy, was larger. Through the whole cross‐section of the canopy, leaf dry weight (DW) and Rubisco content per area decreased by a factor of four, N content by a factor of three, but Chl content only by a factor of 1.7. PSII density decreased by a factor of 1.9, but PSI density by a factor of 3.2. The density of PSI adjusted to shade to a greater extent than the density of PSII. In shade, the distribution of N between the components of the photosynthetic machinery was shifted toward light‐harvesting proteins at the expense of Rubisco. Non‐photosynthetic N decreased the most substantially, from 54% in the sun leaves ofB. pendulato 11% in the shade leaves ofT. cordata. It is concluded that the redistribution of N toward light‐harvesting Chl proteins in shade is not sufficient to keep the excitation rate of a PSII centre invariant. Contrary to PSII, the density of PSI – the photosystem that is in immediate contact with the carbon assimilation system – shade‐adjusts almost proportionally with the latter, whereas its Chl antenna correspondingly increases. Even under N deficiency, a likely condition in the natural plant community, a substantial part of N is stored in non‐photosynthetic proteins under abundant irradiation, but much less under limiting irradiation. At least in trees the general sequence of down‐regulation due to shade adjustment is the following: (1) non‐protein cell structures and non‐photosynthetic proteins; (2) carbon assimilation proteins; (3) light reaction centre proteins, first PSI; and (4) chlorophyll‐binding proteins.
Identification of rice root proteins regulated by gibberellin using proteome analysis
Authors: KONISHI H. , KITANO H. , KOMATSU S.
Published: February 2005

Gibberellin (GA) promoted rice (Oryza sativa L.) root elongation in a concentration‐dependent manner with roots grown in 0.1 µm GA3 being 13.8% longer than controls. On the other hand, the roots of Tan‐ginbozu, a semi‐dwarf cultivar were 69.8% shorter in comparison with Nipponbare, a normal cultivar. Treatments with 10 µm uniconazole‐P and 10 µm abscisic acid (ABA) caused decreases in root length in Tan‐ginbozu by 44.6 and 79.2%, respectively. To investigate how GA influences rice root growth, proteome analysis techniques were applied. Extracted proteins were separated by two‐dimensional polyacrylamide gel electrophoresis and analysed using an automated protein sequencer and mass spectrometer. Sixteen proteins show differences in accumulation levels as a result of treatment with GA3, uniconazole‐P and ABA treatment and/or the difference between the semi‐dwarf cultivar, Tan‐ginbozu, and normal cultivars. Among these proteins, fructose‐bisphosphate aldolase (EC 4.1.2.13) increased in roots treated with GA3, occurred in low levels in Tan‐ginbozu roots, and decreased in roots treated with uniconazole‐P or ABA. Moreover, roots from seedlings grown in 100 µm glucose were 9.1% longer than controls. These results indicate that increases in fructose‐bisphosphate aldolase activity stimulate the glycolytic pathway and may play an important role in the GA‐induced growth of roots.
Regulation of the expression of OsIPS1 and OsIPS2 in rice via systemic and local Pi signalling and hormones
Authors: HOU X. L. , WU P. , JIAO F. C. , JIA Q. J. , CHEN H. M. , YU J. , SONG X. W. , YI K. K.
Published: February 2005

Two genes with a common region that is characteristic of the TPSI1/Mt4 family were cloned from a Pi‐starvation‐induced cDNA library of rice roots using suppression subtracted hybridization (SSH). Based on the consensus sequence of these two genes, members of the TPSI1/Mt4 family were found in maize, wheat and barley. blast and a cluster analysis in the eight members of the TPSI1/Mt4 family showed two classes of four genes each among monocots. The first gene from rice was designated OsIPS1 based on a comparison of the consensus sequence with AtIPS1, and consequently the second gene, which has been previously reported as OsPI1, was designated OsIPS2. Accumulation of the mRNA of OsIPS1/2 was examined by northern blotting and quantitative reverse transcriptase‐polymerase chain reaction in whole‐root and split‐root experiments under treatment with phosphate (Pi) and the Pi analogue phosphite (Phi). OsIPS1 showed much higher mRNA accumulation in roots than OsIPS2, and an opposite trend was seen in shoots. OsIPS1/2 showed both systemic and local responses to Pi starvation, and less than 10% of the overall induced mRNA level was due to the local Pi concentration in roots. The results indicate that Phi may interfere with earlier events in roots that are associated with a local Pi signalling pathway. An analysis of transgenic plants showed that OsIPS1/2 are independently responsive to Pi signalling and are mainly expressed in lateral roots and in the vascular cylinder in the primary root. Exogenous cytokinin (6‐BA) almost completely suppressed systemic Pi starvation signalling and partially suppressed local Pi signalling. Exogenous abscisic acid remarkably reduced Pi starvation signalling. In contrast, exogenous auxin enhanced Pi signalling, especially local Pi signalling in roots. Exogenous ethylene (ethyphon) and the ratio of auxin to cytokinins did not appear to affect the expression of these two genes.
Ectopic expression of nicotianamine synthase genes results in improved iron accumulation and increased nickel tolerance in transgenic tobacco
Authors: DOUCHKOV D. , GRYCZKA C. , STEPHAN U. W. , HELL R. , BÄUMLEIN H.
Published: February 2005

Heavy metals are essential for basic cellular processes but toxic in higher concentrations. This requires the precise control of their intracellular concentrations, a process known as homeostasis. The metal‐chelating, non‐proteinogenous amino acid nicotianamine (NA) is a key component of plant metal assimilation and homeostasis. Its precise function is still unknown. Therefore, this article aims to contribute new information on the in vivo function of NA and to evaluate its potential use for plant nutrition and crop fortification. For this purpose, a nicotianamine synthase gene of Arabidopsis thaliana was ectopically expressed in transgenic tobacco plants. The presence of extra copies of the nicotianamine synthase gene co‐segregated with up to 10‐fold elevated levels of NA in comparison with wild type. The increased NA level led to: (a) a significantly increased iron level in leaves of adult plants; (b) the accumulation of zinc and manganese, but not copper; (c) an improvement of the iron use efficiency in adult plants grown under iron limitation; and (d) an enhanced tolerance against up to 1 m m nickel. Taken together, the data predict that NA may be a useful tool for improved plant nutrition on adverse soils and possibly for enhanced nutritional value of leaf and seed crops.
Growth at moderately elevated temperature alters the physiological response of the photosynthetic apparatus to heat stress in pea (Pisum sativumL.) leaves
Authors: HALDIMANN PIERRE , FELLER URS
Published: February 2005

The impact of heat stress on the functioning of the photosynthetic apparatus was examined in pea (Pisum sativumL.) plants grown at control (25 °C; 25 °C‐plants) or moderately elevated temperature (35 °C; 35 °C‐plants). In both types of plants net photosynthesis (Pn) decreased with increasing leaf temperature (LT) and was more than 80% reduced at 45 °C as compared to 25 °C. In the 25 °C‐plants, LTs higher than 40 °C could result in a complete suppression ofPn. Short‐term acclimation to heat stress did not alter the temperature response ofPn. Chlorophyllafluorescence measurements revealed that photosynthetic electron transport (PET) started to decrease when LT increased above 35 °C and that growth at 35 °C improved the thermal stability of the thylakoid membranes. In the 25 °C‐plants, but not in the 35 °C‐plants, the maximum quantum yield of the photosystem II primary photochemistry, as judged by measuring theFv/Fmratio, decreased significantly at LTs higher than 38 °C. A post‐illumination heat‐induced reduction of the plastoquinone pool was observed in the 25 °C‐plants, but not in the 35 °C‐plants. Inhibition ofPnby heat stress correlated with a reduction of the activation state of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco). Western‐blot analysis of Rubisco activase showed that heat stress resulted in a redistribution of activase polypeptides from the soluble to the insoluble fraction of extracts. Heat‐dependent inhibition ofPnand PET could be reduced by increasing the intercellular CO2concentration, but much more effectively so in the 35 °C‐plants than in the 25 °C‐plants. The 35 °C‐plants recovered more efficiently from heat‐dependent inhibition ofPnthan the 25 °C‐plants. The results show that growth at moderately high temperature hardly diminished inhibition ofPnby heat stress that originated from a reversible heat‐dependent reduction of the Rubisco activation state. However, by improving the thermal stability of the thylakoid membranes it allowed the photosynthetic apparatus to preserve its functional potential at high LTs, thus minimizing the after‐effects of heat stress.
Effects of moderate heat stress on photosynthesis: importance of thylakoid reactions, rubisco deactivation, reactive oxygen species, and thermotolerance provided by isoprene
Authors: SHARKEY THOMAS D.
Published: February 2005

Photosynthesis is particularly sensitive to heat stress and recent results provide important new insights into the mechanisms by which moderate heat stress reduces photosynthetic capacity. Perhaps most surprising is that there is little or no damage to photosystem II as a result of moderate heat stress even though moderate heat stress can reduce the photosynthetic rate to near zero. Moderate heat stress can stimulate dark reduction of plastoquinone and cyclic electron flow in the light. In addition, moderate heat stress may increase thylakoid leakiness. At the same time, rubisco deactivates at moderately high temperature. Relationships between effects of moderate heat on rubisco activation and thylakoid reactions are not yet clear. Reactive oxygen species such as H2O2 may also be important during moderate heat stress. Rubisco can make hydrogen peroxide as a result of oxygenase side reactions and H2O2 production by rubisco was recently shown to increase substantially with temperature. The ability to withstand moderately high temperature can be improved by altering thylakoid lipid composition or by supplying isoprene. In my opinion this indicates that thylakoid reactions are important during moderate heat stress. The deactivation of rubisco at moderately high temperature could be a parallel deleterious effect or a regulatory response to limit damage to thylakoid reactions.
First year donation patterns predict long‐term commitment for first‐time donors
Authors: Schreiber G. B. , Sharma U. K. , Wright D. J. , Glynn S. A. , Ownby H. E. , Tu Y. , Garratty G. , Piliavin J. , Zuck T. , Gilcher R. ,   for the Retrovirus Epidemiology Donor Study
Published: February 2005

Background and Objectives  Converting first‐time donors to become regular donors continues to be a challenge facing blood centres. We examined whether first‐time donors with frequent return in the first 12 months were more likely to become regular donors.

Subjects and Methods  The donation histories of 179 409 community whole‐blood donors, whose first‐time donation in 1991 was negative on donor screening tests, were evaluated. Donors were categorized by the number of donations made in the 12 months after (and including) their first donation. The donor return pattern in the subsequent 6 years, and its association with first‐year donation frequency and demographics, was evaluated by using logistic regression analysis. A ‘regular donor’ was defined as one who returned to donate in at least 4 of the 6 years of follow‐up.

Results  First‐year donation frequency was significantly correlated with long‐term donor return (P < 0·0001). Among those giving 1, 2, 3, 4 and ≥ 5 donations in the first year, 4%, 11%, 21%, 32% and 42%, respectively, became regular donors (P < 0·0001). Similar associations between donation pattern and donor return behaviour were observed after adjusting for demographic variables (P < 0·0001).

Conclusions  Strategies aimed at encouraging current donors to donate more frequently during the first year may help to establish a regular donation behaviour.
Strict red blood cell transfusion guideline reduces the need for transfusions in very‐low‐birthweight infants in the first 4 weeks of life: a multicentre trial
Authors: Miyashiro A. M. , Dos Santos N. , Guinsburg R. , Kopelman B. I. , De Araújo Peres C. , De Lima Taga M. F. , Shinzato A. R. , De Paula Fiod Costa H.
Published: February 2005

Background and Objectives  Very‐low‐birthweight infants are among the most heavily transfused patients. The objective of this study was to verify if the introduction of a strict guideline would reduce the need for red blood cell transfusions in the first 4 weeks of life in these neonates.

Materials and Methods  This was a multicentre prospective study of two cohorts of very‐low‐birthweight infants transfused in accordance with the recommendations of a neonatologist (Phase 1) or according to previously published guidelines (Phase 2).

Results  In the first 28 days of life, 102 patients (68·5%) in Phase 1 and 117 (59·7%) in Phase 2 were transfused. The number of transfusions was 1·9 ± 2·0 in Phase 1 and 1·4 ± 1·6 in Phase 2 (P = 0·01). After adjusting for gestational age, blood loss and the presence of respiratory distress syndrome, the strict guideline reduced the number of transfusions in 17·6% (IC 95%−30·5% to −2·6%).

Conclusions  The strict guideline was effective in reducing erythrocyte transfusions in very‐low‐birthweight infants.
Isolated pulmonary hypertension in scleroderma
Authors: Cox S. R. , Walker J. G. , Coleman M. , Rischmueller M. , Proudman S. , Smith M. D. , Ahern M. J. , Roberts‐Thomson P. J.
Published: February 2005

Background: Isolated pulmonary hypertension (PHT) is now the most frequent cause of disease‐related death in limited cutaneous scleroderma, the commonest disease variant of this disabling connective tissue disorder. Endothelin‐1 receptor antagonists provide symptomatic benefit but to date have not been shown to prolong survival.

Aim: To determine the frequency, disease characteristics and survival of symptomatic patients with isolated PHT in our cohort of scleroderma patients.

Methods: Systematic review of the clinical course of all patients registered on the South Australian Scleroderma Register, a population‐based register of 374 living and 234 deceased patients with scleroderma.

Results: Thirty‐four patients were identified with isolated PHT, the majority with limited scleroderma. From our deceased register, we estimate that >11% of patients with this limited variant will develop this complication. Isolated PHT occurs as a late‐stage complication approximately 20 years after the first symptoms of scleroderma. Patients with isolated PHT were characterized by the presence of multiple telangiectasia, reduced nailfold capillary density, digital ulceration, gross reduction of diffusing capacity for carbon monoxide and echocardiographic evidence of elevated pulmonary artery pressure. Survival was significantly shortened as compared with those patients without this complication (P = 0.002), with a mean survival of 2.5 years from symptomatic onset of PHT.

Conclusion: Isolated PHT occurs as a late‐stage complication in ≥11% of patients with limited cutaneous scleroderma and leads to rapid death from right heart failure. The early use of endothelin‐1 receptor antagonists may change the natural history of this fatal complication. (Intern Med J 2005; 35: 28–33)
Modulation of F1 hybrid stature without altering parent plants through trans‐activated expression of a mutated rice GAI homologue
Authors: Su Ning , Sullivan James A. , Deng Xing Wang
Published: February 2005

Hybrid breeding, by taking advantage of heterosis, brings about many superior properties to the F1 progeny. However, some properties, such as increased plant height, are not desirable for agronomic purposes. To specifically counter the height increase associated with hybrid progeny, we employed an Arabidopsis model and tested a trans‐activation system for specifically expressing a mutated GAI gene only in the F1 hybrid plants to reduce plant stature. A transcriptional activator, the Gal4 DNA‐binding domain fused to the acidic activation domain of herpes simplex virus VP16 protein, driven by a maize ubiquitin promoter, was introduced in one parental line. A rice GAI homologue with an N‐terminal deletion of the DELLA domain, driven by a promoter that is responsive to the transcriptional activator, was transferred into another parental line. After genetic crossing, trans‐activation of the GAI mutant gene resulted in a dwarf phenotype. Over 50 pair‐wise crosses between the parental lines were performed, and analyses suggested that the percentage of F1 progeny exhibiting dwarfism ranged from about 25% to 100%. Furthermore, the dwarfism trait introduced in F1 progeny did not seem to affect total seed yield. Our result suggests the feasibility of manipulating F1 hybrid progeny traits without affecting parent plants or the agronomic property of the progeny.
Gene stacking in transgenic plants – the challenge for 21st century plant biotechnology
Authors: Halpin Claire
Published: February 2005

One of the major technical hurdles impeding the advance of plant genetic engineering and biotechnology is the fact that the expression or manipulation of multiple genes in plants is still difficult to achieve. Although a small proportion of commercial genetically modified (GM) crops present ‘stacked’ or ‘pyramided’ traits, only a handful of products have been developed by introducing three or more novel genes. On the research front, a variety of conventional and more novel methods have been employed to introduce multiple genes into plants, but all techniques suffer from certain drawbacks. In this review, the potential and problems of these various techniques and strategies are discussed, and the prospects for improving these technologies in the future are presented.
Global transcript profiling of potato tuber using LongSAGE
Authors: Nielsen Kåre L. , Grønkjær Karen , Welinder Karen G. , Emmersen Jeppe
Published: February 2005

Solanum tuberosum (potato) is the fourth major crop worldwide and is used for food, feed and biotechnological applications. To fully realize the biosynthetic potential for the production of starch, protein and metabolites, we conducted an extensive quantitative profiling of the expressed genes of mature potato tuber. A total of 58 322 serial analysis of gene expression (SAGE) tags of 19 nucleotides (nt), representing 22 233 different tags, were analysed. The 695 tags seen 10 or more times were assigned a tentative function by comparison with homologous genes. The identities of 12 ‘known’ and 12 ‘unknown’ transcripts were confirmed by rapid amplification of cDNA ends (RACE) cloning using the 19 nt tag as a primer. The SAGE and expressed sequence tag (EST) profiles of potato tuber were compared. Transcripts for four types of protease inhibitor, a metallothionein and a lipoxygenase were more prominent than patatin isoforms.
Modification of gibberellin biosynthesis in the grafted apple scion allows control of tree height independent of the rootstock
Authors: Bulley Sean M. , Wilson Fiona M. , Hedden Peter , Phillips Andrew L. , Croker Stephen J. , James David J.
Published: February 2005

The availability of short stature apple scions that required minimal applications of chemical growth retardants and could be used with a range of rootstocks would be of considerable benefit to fruit growers. We have suppressed the expression of a gene encoding the gibberellin (GA) biosynthetic enzyme GA 20‐oxidase to reduce the levels of bioactive GAs in a scion variety, resulting in significant reductions in stem height. Application of GA3 reversed the effect. The scion remained dwarfed after grafting on to normally invigorating rootstocks, whilst control plants of the same cultivar displayed the expected vigour when grafted on to these rootstocks. This approach could be applicable to any perennial crop variety, allowing dwarf trees to be obtained on any available rootstock or on their own roots without the need for chemical growth retardant application. In effect, seedlings that are well suited to local conditions (drought, salinity) could be employed as tree rootstocks, as could existing rootstocks valued for characters other than vigour control, such as pest and disease resistance.