bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancement of coenzyme binding by a single point mutation at the coenzyme binding domain of E. coli lactaldehyde dehydrogenase
Authors: Rodríguez‐Zavala José Salud 
Published: January 2008

AbstractPhenylacetaldehyde dehydrogenase (PAD) and lactaldehyde dehydrogenase (ALD) share some structural and kinetic properties. One difference is that PAD can use NAD+ and NADP+, whereas ALD only uses NAD+. An acidic residue has been involved in the exclusion of NADP+ from the active site in pyridine nucleotide‐dependent dehydrogenases. However, other factors may participate in NADP+ exclusion. In the present work, analysis of the sequence of the region involved in coenzyme binding showed that residue F180 of ALD might participate in coenzyme specificity. Interestingly, F180T mutation rendered an enzyme (ALD‐F180T) with the ability to use NADP+. This enzyme showed an activity of 0.87 μmol/(min * mg) and Km for NADP+ of 78 μM. Furthermore, ALD‐F180T exhibited a 16‐fold increase in the Vm/Km ratio with NAD+ as the coenzyme, from 12.8 to 211. This increase in catalytic efficiency was due to a diminution in Km for NAD+ from 47 to 7 μM and a higher Vm from 0.51 to 1.48 μmol/(min * mg). In addition, an increased Kd for NADH from 175 (wild‐type) to 460 μM (mutant) indicates a faster product release and possibly a change in the rate‐limiting step. For wild‐type ALD it is described that the rate‐limiting step is shared between deacylation and coenzyme dissociation. In contrast, in the present report the rate‐limiting step in ALD‐F180T was determined to be exclusively deacylation. In conclusion, residue F180 participates in the exclusion of NADP+ from the coenzyme binding site and disturbs the binding of NAD+.
Effect of long‐term cabergoline therapy on the immunological pattern and pituitary function of patients with idiopathic hyperprolactinaemia positive for antipituitary antibodies
Authors: De Bellis A. , Colao A. , Savoia A. , Coronella C. , Pasquali D. , Conte M. , Pivonello R. , Bellastella A. , Sinisi A. A. , Bizzarro A. , Lombardi G. , Bellastella G. 
Published: January 2008

SummaryObjective  The occurrence of antipituitary antibodies (APA) in patients with idiopathic hyperprolactinaemia (IH) and the effects of dopamine agonists on these antibodies and long‐term pituitary function outcome have been so far not evaluated. This longitudinal study was aimed at investigating, in patients with IH the occurrence of APA and the effect of cabergoline on the pituitary function and behaviour of APA.Design  Sixty‐six patients with IH were studied. APA (by indirect immunofluorescence) and pituitary function were investigated every year for 3 years.Results  Seventeen patients resulted APA positive (Group 1) and 49 APA negative (Group 2). Eight patients of Group 1 (Group 1a) and 24 of Group 2 (Group 2a) were asymptomatic and then not treated; instead, nine patients in Group 1 (Group 1b) and 25 in Group 2 (Group 2b), showing symptoms of hyperprolactinaemia, were treated with cabergoline for 2 years.Among the untreated patients, during the follow‐up, those with APA positive (Group 1a) showed an increase of APA titres and PRL levels with partial pituitary impairment in some of them; instead those with APA negative (Group 2a) persisted negative with normal pituitary function despite persistent hyperprolactinaemia. Among the treated patients, those with APA positive (Group 1b) showed normalization of PRL levels, APA disappearance and recovery of pituitary function (when initially impaired) during cabergoline treatment, persisting also at last observation (off‐therapy). Instead all patients of Group 2b persisted with APA negative during the follow‐up with normalization of PRL levels and stable normal pituitary function during cabergoline therapy but showing a further increase of PRL at the last observation.Conclusions  The presence of APA in some patients with IH suggests a possible occurrence of autoimmune hypophysitis at potential/subclinical stage; an early and prolonged cabergoline therapy could interrupt the progression to an overt clinical stage of the disease. However, the small amount of patients investigated suggests caution against generalization of our assumption and prompts to further controlled studies on a more numerous population to verify these conclusions.
Prevalence of GH and other anterior pituitary hormone deficiencies in adults with nonsecreting pituitary microadenomas and normal serum IGF‐1 levels
Authors: Yuen Kevin C. J. , Cook David M. , Sahasranam Prem , Patel Pragnesh , Ghods David E. , Shahinian Hrayr K. , Friedman Theodore C. 
Published: January 2008

SummaryObjective  GH is usually the first pituitary hormone to be affected following a pathological insult to the pituitary; however, data on the prevalence of GH deficiency in patients with nonsecreting pituitary microadenomas and normal serum IGF‐1 levels are scarce. This study aims to evaluate the prevalence of GH and other anterior pituitary hormone deficiencies, and to determine whether microadenomas per se could be associated with reduced GH response rates to GHRH–arginine stimulation.Design  Analytical, retrospective, two‐site case‐control study.Patients and methods  Thirty‐eight patients with nonsecreting pituitary microadenomas (mean size 4·2 mm) and normal serum IGF‐1 levels were studied. Anterior pituitary function testing, including the GHRH–arginine test to examine GH reserve, was performed in all patients. Serum IGF‐1 levels and peak GH levels in the patients that passed the GHRH–arginine test were compared with 22 age‐ and BMI‐matched healthy controls.Results  Nineteen patients (50%) failed the GHRH–arginine test and had higher body mass index (BMI) than those that passed the GHRH–arginine test and healthy controls. Peak GH levels in patients that passed the GHRH–arginine test were lower compared to healthy controls and 19 patients (50%) had at least one other pituitary hormone deficit. A negative correlation (r = –0·42, P < 0·01) between peak GH levels and BMI was identified, but no correlations were found between peak GH and serum IGF‐1 levels.Conclusions  Our data demonstrated that a substantial number of patients with nonsecreting pituitary microadenomas failed the GHRH–arginine test despite normal serum IGF‐1 levels, and had at least one other pituitary hormone deficiency, suggesting that nonsecreting microadenomas may not be clinically harmless. We therefore recommend long‐term follow‐up with periodic basal pituitary function testing, and to consider dynamic pituitary testing should clinical symptoms arise in these patients.
Updating reviews: the experience of the Cochrane Neonatal Review Group
Authors: Soll Roger F. 
Published: January 2008

SummaryMaintaining updated systematic reviews is one of the key goals of the Cochrane Collaboration. Reviews are meant to be updated at an interval of no more than 2 years. The Cochrane Neonatal Review (CNRG) is one of the most productive contributors to the Cochrane Collaboration. However, this means that the CNRG now has a more urgent need to address the issue of review updates. In order to do so, the CNRG has sought methods to prioritise and facilitate the review process.
The temperature response of photosynthesis in tobacco with reduced amounts of Rubisco
Authors: KUBIEN DAVID S. , SAGE ROWAN F. 
Published: January 2008

ABSTRACTThe reasons for the decline in net CO2 assimilation (A) above its thermal optimum are controversial. We tested the hypothesis that increasing the ratio of Rubisco activase to Rubisco catalytic site concentration would increase the activation state of Rubisco at high temperatures. We measured photosynthetic gas exchange, in vivo electron transport (J) and the activation state of Rubisco between 15 and 45 °C, at 38 and 76 Pa ambient CO2, in wild‐type (WT) and anti‐rbcS tobacco. The Rubisco content of the anti‐rbcS lines was 30% (S7‐1) or 6% (S7‐2) of WT, but activase levels were the same in the three genotypes. Anti‐rbcS plants had lower A than WT at all temperatures, but had a similar thermal optimum for photosynthesis as WT at both CO2 levels. In WT plants, Rubisco was fully activated at 32 °C, but the activation state declined to 64% at 42 °C. By contrast, the activation state of Rubisco was above 90% in the S7‐1 line, between 15 and 42 °C. Both A and J declined about 20% from Topt to the highest measurement temperatures in WT and the S7‐1 line, but this was fully reversed after a 20 min recovery at 35 °C. At 76 Pa CO2, predicted rates of RuBP regeneration‐limited photosynthesis corresponded with measured A in WT tobacco at all temperatures, and in S7‐1 tobacco above 40 °C. Our observations are consistent with the hypothesis that the high temperature decline in A in the WT is because of an RuBP regeneration limitation, rather than the capacity of Rubisco activase to maintain high Rubisco activation state.
Deposition and localization of lipid polyester in developing seeds of Brassica napus and Arabidopsis thaliana
Authors: Molina Isabel , Ohlrogge John B. , Pollard Mike 
Published: January 2008

SummaryMature seeds of Arabidopsis thaliana and Brassica napus contain complex mixtures of aliphatic monomers derived from non‐extractable lipid polyesters. Most of the monomers are deposited in the seed coat, and their compositions suggest the presence of both cutin and suberin layers. The location of these polyesters within the seed coat, and their contributions to permeability of the seed coat and other functional properties are unknown. Polyester deposition was followed over Brassica seed development and distinct temporal patterns of monomer accumulation were observed. Octadecadiene‐1,18‐dioate, the major leaf cutin monomer, was transiently deposited. In contrast, the saturated dicarboxylates maintained a constant level during seed desiccation, whereas the fatty alcohols and saturated ω‐hydroxy fatty acids continually increased. Dissection and analysis of Brassica seed coats showed that suberization is not specific to the chalaza. Analysis of the Arabidopsis ap2‐7 mutant suggested that suberin monomers are preferentially associated with the outer integument. Several Arabidopsis knockout mutant lines for genes involved in polyester biosynthesis (att1, fatB and gpat5) were examined for seed monomer load and composition. The variance in polyester monomers of these mutants is correlated with dye penetration assays. Furthermore, stable transgenic plants expressing promoter::YFP fusions showed ATT1 promoter activity in the inner integument, whereas GPAT5 promoter is active in the outer integument. Together, the Arabidopsis data indicated that there is a suberized layer associated with the outer integument and a cutin‐like polyester layer associated with the inner seed coat.
Rapid spatiotemporal patterning of cytosolic Ca2+ underlies flagellar excision in Chlamydomonas reinhardtii
Authors: Wheeler Glen L. , Joint Ian , Brownlee Colin 
Published: January 2008

SummaryCa2+‐dependent signalling processes are implicated in many aspects of flagella function in the green alga, Chlamydomonas. In this study, we examine the spatiotemporal dynamics of cytosolic Ca2+ ([Ca2+]cyt) in single Chlamydomonas cells during the process of flagellar excision, using biolistically loaded calcium‐responsive dyes. Acid‐induced deflagellation occurred in parallel with a single transient elevation in whole‐cell [Ca2+]cyt, which was absent in the acid deflagellation‐deficient adf1 mutant. Deflagellation could also be induced by elevated external Ca2+ ([Ca2+]ext), which promoted very rapid spiking of [Ca2+]cyt across the whole cell and in the flagella. We also detected very rapid apically localised Ca2+ signalling events with an approximate duration of 500 msec. Ninety‐seven per cent of deflagellation events coincided with a rapid elevation in [Ca2+]cyt in the apical region of the cell, either in the form of a whole cell or an apically localised increase, indicating that [Ca2+]cyt elevations in the apical region play an underlying role in deflagellation. Our data indicate that elevated [Ca2+]ext acts to disrupt Ca2+ homeostasis which induces deflagellation by both Adf1‐dependent and Adf1‐independent mechanisms. Elevated [Ca2+]ext also results in further [Ca2+]cyt elevations after the main period of whole cell spiking which are very strongly associated with deflagellation, exhibit a high degree of apical localisation and are largely absent in the adf1 mutant. We propose that these later elevations may act as specific signals for deflagellation.
Phylogenetic footprints in fern spore‐ and seed‐specific gene promoters
Authors: Schallau Anna , Kakhovskaya Irina , Tewes Anne , Czihal Andreas , Tiedemann Jens , Mohr Michaela , Grosse Ivo , Manteuffel Renate , Bäumlein Helmut 
Published: January 2008

SummarySpermatophyte seed‐storage proteins have descended from a group of proteins involved in cellular desiccation/hydration processes. Conserved protein structures are found across all plant phyla and in the fungi andArchaea. We investigated whether conservation in the coding region sequence is paralleled by common gene regulatory processes. Seed‐ and spore‐specific gene promoters of three phylogenetically diverse plants were analysed by transient and transgenic expression inArabidopsis thalianaand tobacco. The transcription factors FUS3 and ABI3, which are central regulators of seed maturation processes, interact withcis‐motifs of seed‐specific promoters from distantly related plants. The promoter of a fern spore‐specific gene encoding a seed‐storage globulin‐like protein exhibits strong seed‐specific activity in both Arabidopsis and tobacco. The existence of phylogenetic footprints indicates good conservation of regulatory pathways controlling gene expression in fern spores and in gymnosperm and angiosperm seeds, reflecting the concerted evolution of coding and regulatory regions.
TECHNICAL ADVANCE: Induction of phenotypic variation by activation of genes harbouring a maize Spm element in their promoter regions using a TnpA–VP16 fusion protein
Authors: Sorokin Alexander P. , Walsh Sean , Baumann Kim , Nichols John , Bevan Michael , Jones Jonathan D.G. , Martin Cathie , Clarke Jonathan H. 
Published: January 2008

SummaryFor many crops, a narrowing genetic base is becoming an increasingly significant problem for improvements made through breeding. Commonly used breeding procedures systematically reduce genetic diversity within elite gene pools. Here we describe a new technique for activation of genes in lines carrying Spm or dSpm transposon insertions. Activation of genes in Arabidopsis harbouring Spm or dSpm insertions in their promoters can be induced by over‐expression of the TnpA–VP16 fusion protein, which binds Spm ends and activates local transcription. As a result, a variety of phenotypes are recovered from multiple‐copy Spm lines in Arabidopsis. Application of this technique to a number of Spm insertion collections in Arabidopsis provides a valuable approach for new insights into plant gene functions. It also provides a proof‐of‐principle demonstration that the method could be used to generate new variation in elite lines of maize.
The gibberellin biosynthetic genes AtGA20ox1 and AtGA20ox2 act, partially redundantly, to promote growth and development throughout the Arabidopsis life cycle
Authors: Rieu Ivo , Ruiz‐Rivero Omar , Fernandez‐Garcia Nieves , Griffiths Jayne , Powers Stephen J. , Gong Fan , Linhartova Terezie , Eriksson Sven , Nilsson Ove , Thomas Stephen G. , Phillips Andrew L. , Hedden Peter 
Published: January 2008

SummaryThe activity of the gibberellin (GA) biosynthetic enzymes GA 20‐oxidases (GA20ox) is of particular importance in determining GA concentration in many plant species. In Arabidopsis these enzymes are encoded by a family of five genes: AtGA20ox1–AtGA20ox5. Transcript analysis indicated that they have different expression patterns and may thus participate differentially in GA‐regulated developmental processes. We have used reverse genetics to determine the physiological roles of AtGA20ox1 and AtGA20ox2, the most highly expressed GA20ox genes during vegetative and early reproductive development. AtGA20ox1 and AtGA20ox2 act redundantly to promote hypocotyl and internode elongation, flowering time, elongation of anther filaments, the number of seeds that develop per silique and elongation of siliques, with AtGA20ox1 making the greater contribution to internode and filament elongation, and AtGA20ox2 making the greater contribution to flowering time and silique length. Pollination of the double mutant with wild‐type pollen indicated that the GA promoting silique elongation is of maternal origin. The ga20ox2 phenotype revealed that GA promotes the number of stem internodes that elongate upon bolting, and does so independently of its effect on internode elongation. Comparison of the phenotype of the double mutant with that of the highly GA‐deficient ga1‐3 mutant indicates that other GA20ox genes contribute to all the developmental processes examined, and, in some cases such as root growth and leaf expansion, make major contributions, as these processes were unaffected in the double mutant. In addition, the effects of the mutations are mitigated by the homeostatic mechanism that acts on expression of other GA dioxygenase and GID1 receptor genes.
Phytochromes and cryptochromes regulate the differential growth of Arabidopsis hypocotyls in both a PGP19‐dependent and a PGP19‐independent manner
Authors: Nagashima Akitomo , Suzuki Genki , Uehara Yukiko , Saji Kensuke , Furukawa Toshiko , Koshiba Tomokazu , Sekimoto Masayo , Fujioka Shozo , Kuroha Takeshi , Kojima Mikiko , Sakakibara Hitoshi , Fujisawa Noriko , Okada Kiyotaka , Sakai Tatsuya 
Published: January 2008

SummaryPhotoreceptors, phytochromes and cryptochromes regulate hypocotyl growth under specific conditions, by suppressing negative gravitropism, modulating phototropism and inhibiting elongation. Although these effects seem to be partially caused via the regulation of the phytohormone auxin, the molecular mechanisms underlying this process are still poorly understood. In our present study, we demonstrate that the flabby mutation enhances both phytochrome‐ and cryptochrome‐inducible hypocotyl bending in Arabidopsis. The FLABBY gene encodes the ABC‐type auxin transporter, PGP19, and its expression is suppressed by the activation of phytochromes and cryptochromes. Our current results therefore indicate that the phytochromes and cryptochromes have at least two effects upon the tropic responses of the hypocotyls in Arabidopsis: the enhancement of hypocotyl bending through the suppression of PGP19, and a PGP19‐independent mechanism that induces hypocotyl bending. By the using an auxin polar transport assay and DR5:GUS expression analysis, we further find that the phytochromes inhibit basipetal auxin transport, and induce the asymmetric distribution of auxin in the hypocotyls. These data suggest that the control of auxin transport by phytochromes and cryptochromes is a critical regulatory component of hypocotyl growth in response to light.
Anthranilate N‐methyltransferase, a branch‐point enzyme of acridone biosynthesis
Authors: Rohde Britta , Hans Joachim , Martens Stefan , Baumert Alfred , Hunziker Peter , Matern Ulrich 
Published: January 2008

SummaryAcridone alkaloids formed by acridone synthase in Ruta graveolens L. are composed of N‐methylanthraniloyl CoA and malonyl CoAs. A 1095 bp cDNA from elicited Ruta cells was expressed in Escherichia coli, and shown to encode S‐adenosyl‐l‐methionine‐dependent anthranilate N‐methyltransferase. SDS–PAGE of the purified enzyme revealed a mass of 40 ± 2 kDa, corresponding to 40 059 Da for the translated polypeptide, whereas the catalytic activity was assigned to a homodimer. Alignments revealed closest relationships to catechol or caffeate O‐methyltransferases at 56% and 55% identity (73% similarity), respectively, with little similarity (∼20%) to N‐methyltransferases for purines, putrescine, glycine, or nicotinic acid substrates. Notably, a single Asn residue replacing Glu that is conserved in caffeate O‐methyltransferases determines the catalytic efficiency. The recombinant enzyme showed narrow specificity for anthranilate, and did not methylate catechol, salicylate, caffeate, or 3‐ and 4‐aminobenzoate. Moreover, anthraniloyl CoA was not accepted. As Ruta graveolens acridone synthase also does not accept anthraniloyl CoA as a starter substrate, the anthranilate N‐methylation prior to CoA activation is a key step in acridone alkaloid formation, channelling anthranilate from primary into secondary branch pathways, and holds promise for biotechnological applications. RT‐PCR amplifications and Western blotting revealed expression of the N‐methyltransferase in all organs of Ruta plants, particularly in the flower and root, mainly associated with vascular tissues. This expression correlated with the pattern reported previously for expression of acridone synthase and acridone alkaloid accumulation.
Reactive oxygen species mediate Na+‐inducedSOS1mRNA stability in Arabidopsis
Authors: Chung Jung‐Sung , Zhu Jian‐Kang , Bressan Ray A. , Hasegawa Paul M. , Shi Huazhong 
Published: January 2008

SummarySalt Overly Sensitive 1 (SOS1), a plasma membrane Na+/H+antiporter in Arabidopsis, is a salt tolerance determinant crucial for the maintenance of ion homeostasis in saline stress conditions.SOS1mRNA is unstable at normal growth conditions, but its stability is substantially increased under salt stress and other ionic and dehydration stresses. In addition, H2O2treatment increases the stability ofSOS1mRNA.SOS1mRNA is inherently unstable and rapidly degraded with a half‐life of approximately 10 min. Rapid decay ofSOS1mRNA requires new protein synthesis. Stress‐inducedSOS1mRNA stability is mediated by reactive oxygen species (ROS). NADPH oxidase is also involved in the upregulation ofSOS1mRNA stability, presumably through the control of extracellular ROS production. Thecis‐element required forSOS1mRNA instability resides in the 500‐bp region within the 2.2 kb at the 3′ end of theSOS1mRNA. Furthermore, mutations in theSOS1gene rendersos1mutants more tolerant to paraquat, a non‐selective herbicide causing oxidative stress, indicating that SOS1 plays negative roles in tolerance of oxidative stress. A hypothetical model for the signaling pathway involving SOS1‐mediated pH changes, NADPH oxidase activation, apoplastic ROS production and downstream signaling transduction is proposed, and the biological significance of ROS‐mediated induction ofSOS1mRNA stability is discussed.
Redundant cis‐acting determinants of 3′ processing and RNA stability in the chloroplast rbcL mRNA of Chlamydomonas
Authors: Goldschmidt‐Clermont Michel , Rahire Michèle , Rochaix Jean‐David 
Published: January 2008

SummaryWe have designed a screen for mutants affected in 3′ maturation of the chloroplast rbcL mRNA in Chlamydomonas reinhardtii. We inserted a spectinomycin resistance cassette, 5′atpA::aadA::3′rbcL, in a peripheral domain of tscA, the gene for a small non‐coding RNA involved in trans‐splicing of psaA. Depending on the orientation of the cassette, a polar effect was observed which was due to processing at the 3′rbcL element: the chimeric tscA RNA was truncated and splicing of psaA was blocked. We selected phenotypic revertants of this insertion mutant that restored psaA splicing, which correlated with the presence of chimeric transcripts that regained the 3′ part of tscA. We analyzed two nuclear and six chloroplast suppressors. Five chloroplast mutations altered a short element in the center of the second inverted repeat in the 3′rbcL (IR2), and one deleted a larger region including this element. These mutations revealed a cis‐acting element in IR2 which is required for 3′ processing. When the same mutations were inserted in the 3′ untranslated region (UTR) of the native rbcL gene, the rbcL mRNA accumulated to normal levels, but in strong alleles its 3′ end was located upstream, near the end of the first inverted repeat (IR1). Deletion of either IR1 or IR2 allowed stable accumulation of rbcL mRNA, but deletion of both resulted in its complete absence. This indicated that the two inverted repeats function as redundant mRNA stability determinants in the 3′ UTR of rbcL.