bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation tagging identifies a gene fromPetunia hybridaresponsible for the production of active cytokinins in plants
Authors: Zubko Elena , Adams Christopher J. , Macháèková Ivana , Malbeck Jiri , Scollan Claire , Meyer Peter 
Published: March 2003

SummaryCytokinins (CKs) are phytohormones that play an important role in plant growth and development. Although the first naturally produced CK, zeatin, was isolated almost four decades ago, no endogenous gene has been shown to produce active CKsin planta. In an activation tagging experiment we have identified a petunia line that showed CK‐specific effects including enhanced shooting, reduced apical dominance and delayed senescence and flowering. This phenotype correlated with the enhanced expression of a gene we labelledSho(Shooting). Sho, which encodes a protein with homology to isopentenyl transferases (IPTs), also causes CK‐specific effects when expressed in other plant species. In contrast to theiptgene fromAgrobacterium, which primarily increases zeatin levels,Shoexpression in petunia and tobacco especially enhances the levels of certain N6‐(Δ2‐isopentenyl) adenosine (2iP) derivatives. Our data suggest thatShoencodes a plant enzyme whose activity is sufficient to produce active CKs in plants.
Identification of Ku70 and Ku80 homologues in Arabidopsis thaliana: evidence for a role in the repair of DNA double‐strand breaks
Authors: Tamura Katsunori , Adachi Yugo , Chiba Keiko , Oguchi Keiko , Takahashi Hideo 
Published: March 2003

SummaryIn higher organisms such as mammals and plants, DNA double‐strand breaks (DSBs) are repaired preferentially by non‐homologous end joining (NHEJ) rather than by homologous recombination. The NHEJ pathway is mediated by Ku, a heterodimer of ≈70 and 80 kDa subunits, which contributes to various aspects of the metabolism of DNA ends in eukaryotic cells. On the basis of their predicted sequence similarity to human Ku70 and Ku80, cDNAs encoding the first plant homologues of these proteins (AtKu70 and AtKu80, respectively) have now been isolated from Arabidopsis thaliana. AtKu70 and AtKu80 share 28.6 and 22.5% amino acid sequence identity with human Ku70 and Ku80, respectively. Yeast two‐hybrid analysis demonstrated that AtKu70 and AtKu80 form a heterodimer, and electrophoretic mobility‐shift assays revealed that this heterodimer binds to double‐stranded telomeric and non‐telomeric DNA sequences, but not to single‐stranded DNA. The AtKu heterodimer also possesses single‐stranded DNA‐dependent ATPase and ATP‐dependent DNA helicase activities. Reverse transcription and the polymerase chain reaction revealed that AtKu70 and AtKu80 genes are expressed widely but at low levels in plant tissues. The expression of these two genes in cultured cells was markedly increased in response to the generation of DSBs by bleomycin or methylmethane sulfonate. These results suggest that the evolutionarily conserved Ku70–Ku80 heterodimer functions in DSB repair by the NHEJ pathway in A. thaliana.
OsPNH1 regulates leaf development and maintenance of the shoot apical meristem in rice
Authors: Nishimura Asuka , Ito Momoyo , Kamiya Noriko , Sato Yutaka , Matsuoka Makoto 
Published: March 2003

SummaryThe Arabidopsis PINHEAD/ZWILLE (PNH/ZLL) gene is thought to play an important role in the formation of the shoot apical meristem (SAM) and in leaf adaxial cell specification. To investigate the molecular mechanisms of rice development, we have isolated a rice homologue of PNH/ZLL, called OsPNH1. Around the SAM, OsPNH1 was strongly expressed in developing leaf primordia, specifically in the presumptive vascular domains, developing vascular tissues, a few cell‐layers of the adaxial region, and future bundle sheath extension cells. In the SAM, only weak expression was observed in the central region, whereas strong expression was detected in the mid‐vein region of leaf founder cells in the peripheral SAM domain. We produced transgenic rice plants containing the antisense OsPNH1 strand. The antisense OsPNH1 plants developed malformed leaves with an altered vascular arrangement and abnormal internal structure. These plants also formed an aberrant SAM with reduced KNOX gene expression. We examined the subcellular localization of the OsPNH1‐GFP fusion protein and found that it was localized in the cytoplasm. On the basis of these observations, we propose that OsPNH1 functions not only in SAM maintenance as previously thought, but also in leaf formation through vascular development.
Tomato LeAGP‐1 arabinogalactan‐protein purified from transgenic tobacco corroborates the Hyp contiguity hypothesis
Authors: Zhao Zhan Dong , Tan Li , Showalter Allan Marshall , Lamport Derek Thomas Anthony , Kieliszewski Marcia Jane 
Published: March 2003

SummaryFunctional analysis of the hyperglycosylated arabinogalactan‐proteins (AGPs) attempts to relate biological roles to the molecular properties that result largely from O‐Hyp glycosylation putatively coded by the primary sequence. The Hyp contiguity hypothesis predicts contiguous Hyp residues as attachment sites for arabino‐oligosaccharides (arabinosides) and clustered, non‐contiguous Hyp residues as arabinogalactan polysaccharide sites. Although earlier tests of naturally occurring hydroxyproline‐rich glycoproteins (HRGPs) and HRGPs designed by synthetic genes were consistent with a sequence‐driven code, the predictive value of the hypothesis starting from the DNA sequences of known AGPs remained untested due to difficulties in purifying a single AGP for analysis. However, expression in tobacco (Nicotiana tabacum) of the major tomato (Lycopersicon esculentum) AGP, LeAGP‐1, as an enhanced green fluorescent protein fusion glycoprotein (EGFP)‐LeAGP‐1, increased its hydrophobicity sufficiently for chromatographic purification from other closely related endogenous AGPs. We also designed and purified two variants of LeAGP‐1 for future functional analysis: one lacking the putative glycosylphosphatidylinositol (GPI)‐anchor signal sequence; the other lacking a 12‐residue internal lysine‐rich region. Fluorescence microscopy of plasmolysed cells confirmed the location of LeAGP‐1 at the plasma membrane outer surface and in Hechtian threads. Hyp glycoside profiles of the fusion glycoproteins gave ratios of Hyp‐polysaccharides to Hyp‐arabinosides plus non‐glycosylated Hyp consistent with those predicted from DNA sequences by the Hyp contiguity hypothesis. These results demonstrate a route to the purification of AGPs and the use of the Hyp contiguity hypothesis for predicting the Hyp O‐glycosylation profile of an HRGP from its DNA sequence.
Characterization of a HKT‐type transporter in rice as a general alkali cation transporter
Authors: Golldack Dortje , Su Hua , Quigley Francoise , Kamasani Uma R. , Muñoz‐Garay Carlos , Balderas Enrique , Popova Olga V. , Bennett John , Bohnert Hans J. , Pantoja Omar 
Published: March 2003

SummaryWe report the characterization of rice OsHKT1 (Oryza sativa ssp. indica) homologous to the wheat K+/Na+‐symporter HKT1. Expression of OsHKT1 in the yeast strain CY162 defective in K+‐uptake restored growth at mM and µM concentrations of K+ and mediated hypersensitivity to Na+. When expressed in Xenopus oocytes, rice OsHKT1 showed uptake characteristics of a Na+‐transporter but mediated transport of other alkali cations as well. OsHKT1 expression was analysed in salt‐tolerant rice Pokkali and salt‐sensitive IR29 in response to external cation concentrations. OsHKT1 is expressed in roots and leaves. Exposure to Na+, Rb+, Li+, and Cs+ reduced OsHKT1 transcript amounts in both varieties and, in some cases, incompletely spliced transcripts were observed. By in situ hybridizations the expression of OsHKT1 was localized to the root epidermis and the vascular tissue inside the endodermis. In leaves, OsHKT1 showed strongest signals in cells surrounding the vasculature. The repression of OsHKT1 in the two rice varieties during salt stress was different in various cell types with main differences in the root vascular tissue. The data suggest control over HKT expression as a factor that may distinguish salt stress‐sensitive and stress‐tolerant lines. Differences in transcript expression in space and time in different lines of the same species appear to be a component of ion homeostasis correlated with salt sensitivity and tolerance.
A role for HKT1 in sodium uptake by wheat roots
Authors: Laurie Sophie , Feeney Kevin A. , Maathuis Frans J. M. , Heard Peter J. , Brown Sherralyn J. , Leigh Roger A. 
Published: March 2003

SummaryThe high affinity potassium transporter, HKT1 from wheat was introduced into Florida wheat in sense and antisense orientation under control of a ubiquitin promoter. Ten transgenic lines expressing the transgene were identified and two of these showed strong down‐regulation of the native HKT1 transcript. One line (271) was expressing the antisense construct and the other (223) was expressing a truncated sense construct. The two lines were examined further for phenotype relating to cation transport. Membrane depolarisations were measured in low (0.1 mm) K+ and high (100 mm) NaCl. Under these conditions there was no difference between line 271 and the control at low K+, but at high Na+ there was a rapid depolarisation that was significantly larger in control plants. 22Na uptake was measured in this line and there was a significant decrease in uptake at 100 mm NaCl in the transgenic line when compared with the control. The two transgenic lines were grown at high NaCl (200 mm) and analysed for growth and root sodium content. Lines 271 and 223 showed enhanced growth under salinity when compared with the control and had lower sodium in the root. Secondary ion mass spectrometry (SIMS) analysis of transverse sections of the root showed that Na+ and K+ were strongly localised to stelar regions when compared with other ions, and that the Na+ : K+ ratios were reduced in salt‐stressed transgenic tissue when compared with the control.
Construction of a ‘unigene’ cDNA clone set by oligonucleotide fingerprinting allows access to 25 000 potential sugar beet genes
Authors: Herwig Ralf , Schulz Britta , Weisshaar Bernd , Hennig Steffen , Steinfath Matthias , Drungowski Mario , Stahl Dietmar , Wruck Wasco , Menze Andreas , O'Brien John , Lehrach Hans , Radelof Uwe 
Published: March 2003

SummaryAccess to the complete gene inventory of an organism is crucial to understanding physiological processes like development, differentiation, pathogenesis, or adaptation to the environment. Transcripts from many active genes are present at low copy numbers. Therefore, procedures that rely on random EST sequencing or on normalisation and subtraction methods have to produce massively redundant data to get access to low‐abundance genes. Here, we present an improved oligonucleotide fingerprinting (ofp) approach to the genome of sugar beet (Beta vulgaris), a plant for which practically no molecular information has been available. To identify distinct genes and to provide a representative ‘unigene’ cDNA set for sugar beet, 159 936 cDNA clones were processed utilizing large‐scale, high‐throughput data generation and analysis methods. Data analysis yielded 30 444 ofp clusters reflecting the number of different genes in the original cDNA sample. A sample of 10 961 cDNA clones, each representing a different cluster, were selected for sequencing. Standard sequence analysis confirmed that 89% of these EST sequences did represent different genes. These results indicate that the full set of 30 444 ofp clusters represent up to 25 000 genes. We conclude that the ofp analysis pipeline is an accurate and effective way to construct large representative ‘unigene’ sets for any plant of interest with no requirement for prior molecular sequence data.
An Arabidopsis thaliana knock‐out mutant of the chloroplast triose phosphate/phosphate translocator is severely compromised only when starch synthesis, but not starch mobilisation is abolished
Authors: Schneider Anja , Häusler Rainer E. , Kolukisaoglu Üner , Kunze Reinhard , Van Der Graaff Eric , Schwacke Rainer , Catoni Elisabetta , Desimone Marcelo , Flügge Ulf‐Ingo 
Published: March 2003

SummaryThe Arabidopsis thaliana tpt‐1 mutant which is defective in the chloroplast triose phosphate/phosphate translocator (TPT) was isolated by reverse genetics. It contains a T‐DNA insertion 24 bp upstream of the start ATG of the TPT gene. The mutant lacks TPT transcripts and triose phosphate (TP)‐specific transport activities are reduced to below 5% of the wild type. Analyses of diurnal variations in the contents of starch, soluble sugars and phosphorylated intermediates combined with 14CO2 labelling studies showed, that the lack of TP export for cytosolic sucrose biosynthesis was almost fully compensated by both continuous accelerated starch turnover and export of neutral sugars from the stroma throughout the day. The utilisation of glucose 6‐phosphate (generated from exported glucose) rather than TP for sucrose biosynthesis in the light bypasses the key regulatory step catalysed by cytosolic fructose 1,6‐bisphosphatase. Despite its regulatory role in the feed‐forward control of sucrose biosynthesis, variations in the fructose 2,6‐bisphosphate content upon illumination were similar in the mutant and the wild type. Crosses of tpt‐1 with mutants unable to mobilise starch (sex1) or to synthesise starch (adg1‐1) revealed that growth and photosynthesis of the double mutants was severely impaired only when starch biosynthesis, but not its mobilisation, was affected. For tpt‐1/sex1 combining a lack in the TPT with a deficiency in starch mobilisation, an additional compensatory mechanism emerged, i.e. the formation and (most likely) fast turnover of high molecular weight polysaccharides. Steady‐state RNA levels and transport activities of other phosphate translocators capable of transporting TP remained unaffected in the mutants.
Prenylcysteine α‐carboxyl methyltransferase expression and function in Arabidopsis thaliana
Authors: Narasimha Chary S. , Bultema Rebecca L. , Packard Clay E. , Crowell Dring N. 
Published: March 2003

SummaryFarnesylated proteins undergo a series of post‐translational modifications, including carboxyl terminal isoprenylation, proteolysis, and methylation. In Arabidopsis thaliana, protein farnesylation has been shown to be necessary for negative regulation of ABA signaling. However, the role of post‐isoprenylation protein processing in ABA signal transduction has not been described. Here, we show that the A. thaliana genome contains two distinct genes on chromosome V, AtSTE14A and AtSTE14B, which encode functional prenylcysteine α‐carboxyl methyltransferases. AtSTE14B encodes a methyltransferase with lower apparent Kms for prenylcysteine substrates and higher specific activities than the previously described AtSTE14A‐encoded methyltransferase. Furthermore, whereas AtSTE14A transcription is restricted to root and shoot tips, young leaves, and vascular tissue, AtSTE14B transcription is observed in all organs except hypocotyls and petioles. Pharmacological inhibitors of prenylcysteine α‐carboxyl methyltransferase activity cause increased ABA sensitivity, seed dormancy, and stomatal closure, consistent with the hypothesis that prenylcysteine α‐carboxyl methylation is necessary for negative regulation of ABA signaling. These results suggest that carboxyl methylation, which is a reversible and potentially regulated step in the processing, targeting, and function of isoprenylated plant proteins, may be an important biochemical target for introducing altered ABA sensitivity and drought tolerance into plants.
Overexpression of Bax inhibitor suppresses the fungal elicitor‐induced cell death in rice (Oryza sativa L.) cells
Authors: Matsumura H. , Nirasawa S. , Kiba A. , Urasaki N. , Saitoh H. , Ito M. , Kawai‐Yamada M. , Uchimiya H. , Terauchi R. 
Published: March 2003

SummaryTreatment of suspension‐cultured cells of rice (Oryza sativa L.) with cell wall extract of rice blast fungus (Magnaporthe grisea) elicits a rapid generation of H2O2, alkalinization of culture medium, and eventual cell death. To elucidate genes involved in these processes, we exploited SAGE (Serial Analysis of Gene Expression) technique for the molecular analysis of cell death in suspension‐cultured cells treated with the elicitor. Among the downregulated genes in the elicitor‐treated cells, a BI‐1 gene coding for Bax inhibitor was identified. Transgenic rice cells overexpressing Arabidopsis BI‐1 gene showed sustainable cell survival when challenged with M. grisea elicitor. Thus, the plant Bax inhibitor plays a functional role in regulating cell death in the rice cell culture system.
Monitoring transfusion practice – a computerized procedure
Authors: Titlestad K. , Kristensen T. , Jorgensen J. , Georgsen J. 
Published: March 2003

Summary As the description of transfusion practice over time requires the handling of massive amounts of data, and because the majority of records have until now been paper‐based, little is known about the epidemiology of blood transfusion. Furthermore, most previous studies have collected data manually from patient records or from computerized registers created solely for study purposes.We describe a procedure for monitoring transfusion practices based exclusively upon the collection of data from the existing computerized registers. During the calendar years 1997 and 1998, more than 750 000 data records were collected from the blood transfusion registers, diagnosis and procedure registers, and clinical biochemistry registers at two university hospitals. Linking of the data required a unique and consistent identification of all data records. This was made possible by the national Personal Identification Number. In this way more than 98% of all transfusions could be identified and approximately 95% (77 950) could be connected to a principal diagnosis.The described procedure creates new opportunities for studies of transfusion practices both on a large scale and in richness of detail, and we propose to establish a network where transfusion practices data are available and comparable for individual departments, hospitals, whole regions, and possibly nations.
Platelet concentrates derived from buffy coat and apheresis: biochemical and functional differences
Authors: Böck M. , Rahrig S. , Kunz D. , Lutze G. , Heim M. U. 
Published: March 2003

Summary Today, platelet concentrates are generally produced from whole blood by differential centrifugation (buffy coat‐derived platelet concentrates – PCs) or by plateletpheresis (apheresis‐derived platelet concentrates – APCs). As PCs are characterized by a lower number of platelets than APCs, four to six PCs are customarily combined in order to obtain an equivalent dose. In the 1970s and 1980s, the use of PCs exceeded that of APCs by far; in contrast, since the beginning of the 1990s, APCs comprise more than half of all transfused platelets. However, the selection of PCs or APCs for transfusion to thrombocytopenic patients is still a matter of debate.The present paper compares biochemical and functional properties of both platelet preparations in vitro. Besides plasma parameters (e.g. platelet factor 4 (PF4), P‐selectin, C3a‐desarginin, plasma coagulation factors), platelet function was analysed by aggregometry and the PFA 100 system. APCs are characterized by a better preservation of ADP and collagen‐induced platelet aggregation, and shorter closure times of the PFA 100 test system during storage. The improved primary in vitro haemostatic capacity of APCs is presumed to be owing to a lower cellular activation rate in these preparations. This hypothesis is supported by the higher plasma concentrations of PF4, β‐thromboglobulin and P‐selectin found in PCs compared with APCs. The concentrations of C3a‐desarginin in PCs exceed those in APCs by far. Additionally, thrombin generation is higher in PCs than in APCs.These data suggest that APCs are characterized by a superior haemostatic capacity over PCs in vitro. However, in vivo studies should be performed to confirm these findings in the patients' circulation also.
Obstetric care in southern Tanzania: does it reach those in need?
Authors: Jahn Albrecht , Kowalewski Marga , Kimatta Suleiman S. 
Published: March 2003

Summary
objective  To assess whether antenatal care achieves identification and timely referral of high‐risk pregnancies in southern Tanzania. methods  We compared the risk profiles of pregnant women in general with those attending obstetric care and investigated the reasons for seeking care. The risk profile of inpatients was drawn up through interviews with maternity cases and analysis of their antenatal records at the regional referral hospital (n= 415); population‐based data on the prevalence of specific risk factors were obtained from entries in antenatal care registers (n= 1630) and from literature. results  A significant risk selection towards obstetric referral level care was observed only for previous caesarean section (prevalence hospital 6.7% all pregnancies 1.5%P < 0.005) and for nulliparity (hospital 42.8% all pregnancies 25.0%P < 0.005). No significant differences were observed for other risk factors such as previous perinatal death height < 150 cm multiple gestation and breech presentation. Prevalence of the risk factors age > 34 years and grand multiparity was significantly lower among hospital users. Coverage of obstetric care was below 50% for all risk factors except previous caesarean section (91.5%) conclusion  Despite pursuing the risk approach and very good coverage, antenatal care in Tanzania has only limited effect on extending obstetric care to high‐risk mothers. A critical review of the present screening and counselling practices, including a more focused and client‐centred application of risk assessment, is warranted.
Detection of Trypanosoma brucei gambiense in sleeping sickness suspects by PCR amplification of expression‐site‐associated genes 6 and 7
Authors: Kabiri Mostafa , Franco José R. , Simarro Pere P. , Ruiz J. Antonio , Sarsa Mario , Steverding Dietmar 
Published: March 2003

Summary We have developed a sensitive and specific method to identify Trypanosoma brucei ssp. using PCR to amplify conserved expression‐site‐associated gene 6 and 7 DNA target sequences. Amplification of 10% of the DNA in a single trypanosome produced sufficient PCR product to be visible as a band in an agarose gel stained with ethidium bromide. We analysed 59 blood samples of serologically positive cases of sleeping sickness by PCR, and directed parasitological examination of tissue fluids. The PCR test detected 87% of the parasitologically positive cases, with a specificity of 97%. In 5 cases, the parasite was demonstrated by the PCR test 4–6 months prior to parasitological detection. This result shows the potential of the assay in early diagnosis of actual T. b. gambiense infections in apparently aparasitaemic sleeping sickness patients.