bluuebunny/crossref_metadata_2025_split huggingface dataset:
cDNA cloning and characterisation of an α‐glucosidase gene from potato (Solanum tuberosum L.)
Authors: Taylor Mark A. , George Lesley A. , Ross Heather A. , Davies Howard V. 
Published: March 2003

SummaryUsing an Arabidopsis thaliana expressed sequence tag with sequence similarity to human lysosomal α‐glucosidase as a probe, a potato cDNA was isolated. The cDNA encodes a polypeptide with an Mr value of 105,400 and the most significant matches of the deduced amino acid sequence are with members of family 31 of glucosyl transferase. The potato cDNA was expressed in a strain of Saccharomyces cerevisiae that is deficient in maltase activity and unable to grow using maltose as a carbon source (ABYSMAL81). Expression of the potato cDNA in the mutant yeast strain restores its ability to use maltose as a carbon source for growth. Additionally, α‐glucosidase activity could be measured in extracts of the yeast cells following complementation. A range of maltodextrins were substrates for this activity. The steady‐state expression level of the potato α‐glucosidase gene was low in most tissues examined, the highest levels occurring in sprouting tubers and source leaves.
The characterization ofgio, a new pea mutant, shows the role of indoleacetic acid in the control of fruit development by the apical shoot
Authors: Rodrigo Ma Jesús , López‐Díaz Isabel , García‐Martínez José L. 
Published: March 2003

SummaryFruit‐set and fruit growth in pea (Pisum sativumL.) depend on gibberellins (GAs). The authors have isolated a new pea mutant,gio, which appeared spontaneously within the population of the cultivar Alaska, characterized by unpollinated ovaries much less sensitive to applied GAs. The mutant also has elongated peduncles, and is taller than the wild‐type (WT) because the upper plant internodes are longer. Contrary to WT, thegioovaries respond very little to benzylaminopurine (BAP) and 2,4‐dichlorophenoxyacetic acid, but become fully sensitive to GA3when this hormone is applied together with BAP. Thegiophenotype is determined by a mutation at a single mendelian locus. The mutation is recesive, shows incomplete penetrance, and its expression depends on environmental culture conditions. The sensitivity of the ovaries to GA3can be recovered by removing the apical shoot (plant decapitation) and by blocking the transport of indoleacetic acid (IAA) from the apical shoot with 2,3,5‐triiodobenzoic acid. The content of IAA in methanolic extracts and phloematic exudates of the apical shoot ofgiois about double that in the WT. The rate of transport of [3H]IAA applied to the apex of the mutant is also twice that in the WT. This indicates that the insensitivity of thegioovaries to GAs is due to the inhibitory effect of the higher basipetal IAA transport from the shoot. The interaction between the fruit and the apical shoot mediated by IAA probably also involves cytokinins transported from the basal part of the plant.
Signs of translational regulation within the transcript leader of a plant plasma membrane H+‐ATPase gene
Authors: Lukaszewicz Marcin , Jérouville Bénédicte , Boutry Marc 
Published: March 2003

SummaryTranscripts of most plant plasma membrane H+‐ATPase genes possess a leader (5′ untranslated region) that is unusually long and that contains a short upstream open reading frame (uORF), two features which suggest post‐transcriptional regulation. To investigate the putative role of the transcript leader, we have placed the leader of pma3, one of the Nicotiana plumbaginifolia H+‐ATPase genes, between the CaMV 35S promoter and the sequence coding for the β‐glucuronidase (GUS) reporter gene. Transient expression of this chimeric gene and of derived mutants was analysed in electroporated tobacco protoplasts. The whole leader had a positive effect on translation, since deletion of most of its sequence reduced GUS activity. Suppression of the uORF by point mutation of its initiating AUG increased GUS activity by about 55%. Analysis of various deletions and mutations suggested that the uORF is translated by at least two‐thirds of scanning ribosomes, half of which subsequently reinitiate downstream translation under our experimental conditions. Reinitiation did not depend on the nucleotide sequence of the uORF, nor on that separating the uORF and the main open reading frame. We conclude that the pma3 transcript possesses features of translational regulation, whose mode of functioning has yet to be discovered.
C4‐type gene expression is not directly dependent on Kranz anatomy in an amphibious sedge Eleocharis vivipara Link
Authors: Uchino Akira , Sentoku Naoki , Nemoto Keisuke , Ishii Ryuichi , Samejima Muneaki , Matsuoka Makoto 
Published: March 2003

Summary Eleocharis vivipara Link alters its photosynthetic mode depending on the growth environment. It utilizes C4 photosynthesis when grown under terrestrial conditions (terrestrial form) and C3 photosynthesis when grown under submerged conditions (submerged form). The photosynthetic organ (the mature internodal region of the culm) of the terrestrial form shows typical Kranz anatomy with well‐developed bundle sheath cells, while the bundle sheath cells of the submerged form are not developed. In the mature internodal region of the terrestrial form, expression of the genes encoding two carboxylases, the small subunit of ribulose 1,5‐bisphosphate carboxylase (RbcS) and phosphoenolpyruvate carboxylase (Ppc), occurred mainly in bundle sheath cells and in mesophyll cells, respectively, as seen in a typical C4 leaf. In the submerged form, RbcS was expressed in both bundle sheath cells and mesophyll cells, and no expression of Ppc was observed. In the immature internodal region with undeveloped bundle sheath cells, both life forms showed the same expression pattern as in C3 plants: RbcS expression was localized in mesophyll cells and no Ppc expression was observed. The C4‐type expression pattern was established concomitantly with the development of bundle sheath cells during tissue maturation in the terrestrial internode. In contrast to the terrestrial form, the submerged form maintains C3‐type gene expression during tissue maturation. When the terrestrial culm was submerged, a region of transition from the terrestrial form to the submerged form was established in newly sprouting culms. In this transitional region, C4‐type expression of the two carboxylase genes was still maintained even though the development of bundle sheath cells was repressed. This observation suggests that the C4‐type cell‐specific gene expression pattern does not depend on the formation of Kranz anatomy.
NADPH is a specific inhibitor of protein import into glyoxysomes
Authors: Pool Martin R. , López‐Huertas Eduardo , Horng Jim‐Tong , Baker Alison 
Published: March 2003

SummaryWe have studied the import of proteins into glyoxysomes in vitro and show that this process is specifically inhibited by NADPH. NADPH affects both binding and translocation of proteins into glyoxysomes, and inhibition is determined by the ratio of NADP+ to NADPH. The site of action of NADPH is most likely within the glyoxysome because (1) pretreatment of glyoxysomes with NADPH, followed by re‐isolation of the organelles prior to the import assay, resulted in inhibition of import that could be restored by the addition of NADP+; (2) low concentrations of NADPH inhibited binding of proteins to broken glyoxysome membranes. The sensitivity of protein import to inhibition by NADPH declines as glyoxysomes are converted to leaf‐type peroxisomes. A model is proposed that speculates on a possible role for NADPH in regulating protein import into plant peroxisomes.
STF1 is a novel TGACG‐binding factor with a zinc‐finger motif and a bZIP domain which heterodimerizes with GBF proteins
Authors: Cheong Yong Hwa , Yoo Cheol Min , Park Jeong Mee , Ryu Gyeong Ryeol , Goekjian Virginia H. , Nagao Ron T. , Key Joe L. , Cho Moo Je , Hong Jong Chan 
Published: March 2003

SummaryTwo separate nuclear binding activities (B1 and B2) in the soybean apical hypocotyl have been identified that interact with a palindromic C‐box sequence (TGACGTCA) and which are developmentally regulated in an inverse manner. The bZIP factors responsible for these two binding activities, B1 and B2, were isolated from a cDNA library and designated STGA1 and STFs (STF1 and STF2), respectively. Sequence analysis shows that the STFs contain both a zinc‐finger domain and a bZIP domain. The two zinc finger sequences of Cys4–Cys4 are most related to the RING zinc‐finger motif carrying a Cys3‐His‐Cys4. In addition the bZIP domain of STFs is highly homologous to the HY5 protein of Arabidopsis. DNA binding studies revealed that STF1 binding to the TGACGT sequence requires distinct flanking sequences. Furthermore, STF1 binds to the Hex sequence as a heterodimer with G‐box binding factors (GBFs), a feature not observed with STGA1. Since STF1 expression is most prevalent in apical and elongating hypocotyls, it is proposed that STF1 may be a transcription factor involved in the process of hypocotyl elongation.
Conservation of gene structure and activity in the regulation of reproductive organ development of conifers and angiosperms
Authors: Tandre Karolina , Svenson Marie , Svensson Mats E. , Engström Peter 
Published: March 2003

SummaryThe Norway spruce (Picea abies) gene DAL2 shows distinct structural similarities to angiosperm MADS‐box genes which act in the control of the development of the sexual organs of the flower. Transcription of DAL2 is restricted to the reproductive organs, the unisexual cones, of Norway spruce. In this paper we show that DAL2 in the compound female cone is exclusively expressed in the developing ovule‐bearing organ, the ovuliferous scale. When expressed constitutively in transgenic Arabidopsis the gene causes developmental alterations very similar to those observed in plants ectopically expressing the Arabidopsis gene AGAMOUS and the closely related Brassica napus gene BAG1. These alterations include homeotic transformations of floral organs. On the basis of these data and analysis of the phylogeny of the plant MADS‐box gene family, we propose that DAL2 acts to control reproductive organ development in spruce. We also propose that DAL2 shares a common origin with AGAMOUS and related genes from other angiosperms, in an ancestral MADS‐box gene that was active in the control of ontogeny of ovule‐bearing organs in the unknown last common ancestor of conifers and angiosperms.
A mutant deficient in the plastid lipid DGD is defective in protein import into chloroplasts
Authors: Chen Lih‐Jen , Li Hsou‐min 
Published: March 2003

Summary Most proteins in chloroplasts are encoded by the nuclear genome and synthesized in the cytosol with N‐terminal extensions called transit peptides. Transit peptides function as the import signal to chloroplasts. The import process requires several protein components in the envelope and stroma and also requires the hydrolysis of ATP. Lipids have been implicated in the import process based on theories or experiments with

in vitro

model systems. We show here that chloroplasts isolated from an

Arabidopsis

mutant deficient in the plastid lipid digalactosyl diacylglycerol (DGD) were normal in importing a chloroplast outer membrane protein, but were defective in importing precursor proteins targeted to the interior of chloroplasts. The impairment includes the binding, or docking, step of the import process that is supported by 100 μM ATP.
The transient nature of the oligogalaturonide‐induced ion fluxes of tobacco cells is not correlated with fragmentation of the oligogalacturonides
Authors: Mathieu Yves , Guern Jean , Spiro Mark D. , O’Neill Malcolm A. , Kates Keith , Darvill Alan G. , Albersheim Peter 
Published: March 2003

Summary The metabolism by suspension‐cultured tobacco cells of oligogalacturonides was investigated. Dodecagalacturonic acid‐[3H]galactitol induces a rapid and transient alkalinization of the incubation medium resulting in part from enhanced K+ efflux from tobacco cells. However, a threefold higher concentration of dodecagalacturonic acid‐[3H]galactitol is required to induce a response with the same amplitude and kinetics as that induced by the unreduced tridecagalacturonic acid. Approximately 20% of the dodecagalacturonic acid‐[3H]galactitol added to suspension‐cultured tobacco ionically binds to the cell walls within 1 min; maximum binding (approximately 30% of the oligogalacturonide) occurs in approximately 25 min. The unbound dodecagalacturonic acid‐[3H]galactitol is rapidly (half‐life, 30 min) fragmented to smaller, biologically inactive fragments by a polygalacturonase present in the growth medium. In contrast, the wall‐bound dodecagalacturonic acid‐[3H]galactitol is not degraded for at least 150 min. However, the kinetics, amplitude and duration of oligogalacturonide‐induced ion fluxes are not correlated with the rate at which oligogalacturonides are converted to biologically inactive fragments. We propose that the transient nature of the oligogalacturonide‐induced responses is likely to result from a temporary desensitization of the plant cells to the bioactive oligogalacturonides.
Plants have a sensitive perception system for the most conserved domain of bacterial flagellin
Authors: Felix Georg , Duran Juliana D. , Volko Sigrid , Boller Thomas 
Published: March 2003

SummaryThe flagellum is an important virulence factor for bacteria pathogenic to animals and plants. Here we demonstrate that plants have a highly sensitive chemoperception system for eubacterial flagellins, specifically targeted to the most highly conserved domain within its N terminus. Synthetic peptides comprising 15–22 amino acids of this domain acted as elicitors of defence responses at sub‐nanomolar concentrations in cells of tomato and several other plant species. Peptides comprising only the central 8 to 11 amino acids of the active domain had no elicitor activity but acted as specific, competitive inhibitors in tomato cells. These antagonists suppressed the plant’s response to flagellin, crude bacterial extracts and living bacterial cells. Thus, plants have a highly sensitive and selective perception system for the flagellin of motile eubacteria.
M phase‐specific activation of theNicotiana sylvestris Cyclin B1promoter involves multiple regulatory elements
Authors: Tréhin Christophe , Glab Nathalie , Perennes Claudette , Planchais Séverine , Bergounioux Catherine 
Published: March 2003

Summary B‐type cyclins are cell cycle regulatory proteins specifically expressed in G2‐M phases. To understand the mechanisms that regulate their expression, it is important to identify the required promoter element(s). By using synchronized BY‐2 cell cultures stably transformed with chimeric genes composed of sequential Nicsy;

CycB1

; 1 promoter deletions fused to the β‐glucuronidase reporter gene (

gus

), we show that at least five distinct promoter regions are required for maximal M‐phase expression. Furthermore, two distinct promoter regions contain sufficient element(s) to induce M‐phase‐specific expression. In one of these regions, a 23 bp promoter element is able to activate reporter gene expression in cells induced to divide in an orientation‐independent manner but without an M‐phase specific expression. Therefore, this 23 bp element, which contains a 5 bp element identical to the MYB binding core, is a good upstream activating sequence (UAS) candidate. Moreover, electrophoretic mobility shift assays show that this putative UAS specifically binds protein complexes that appear to differ whether cells are cycling or not. The constitutive transcriptional activation mediated by this UAS would suggest that the Nicsy;

CycB1

; 1 gene promoter is regulated through an activation/repression mechanism.
Characterization of the ABA‐deficient tomato mutantnotabilisand its relationship with maizeVp14
Authors: Burbidge Alan , Grieve Teresa M. , Jackson Alison , Thompson Andrew , McCarty Donald R. , Taylor Ian B. 
Published: March 2003

Summary The

notabilis

(

not

) mutant of tomato has a wilty phenotype due to a deficiency in the levels of the plant hormone abscisic acid (ABA). The mutant appears to have a defect in a key control step in ABA biosynthesis – the oxidative cleavage of a 9‐

cis

xanthophyll precursor to form the C15 intermediate, xanthoxin. A maize mutant,

viviparous 14

(

vp14

) was recently obtained by transposon mutagenesis. This maize genetic lesion also affects the oxidative cleavage step in ABA synthesis. Degenerate primers for PCR, based on the VP14 predicted amino acid sequence, have been used to provide probes for screening a wilt‐related tomato cDNA library. A full‐length cDNA clone was identified which is specific to the

not

gene locus. The ORFs of the tomato cDNA and maize

Vp14

are very similar, apart from parts of their N‐terminal sequences. The

not

mutation has been characterized at the DNA level. A specific A/T base pair deletion of the coding sequence has resulted in a frameshift mutation, indicating that

not

is a null mutant. This observation is discussed in connection with the relatively mild phenotype exhibited by

not

mutant homozygotes.
The accumulation of triacylglycerols within the endoplasmic reticulum of developing seeds ofHelianthus annuus
Authors: Lacey Dominic J. , Beaudoin Frédéric , Dempsey Christopher E. , Shewry Peter R. , Napier Johnathan A. 
Published: March 2003

Summary Microsomes isolated from developing seeds of

Helianthus annuus

were prepared in a medium which ensured that endoplasmic reticulum (ER)‐bound polysomes remained attached to the ER during homogenization. The microsomes were then incubated with the substrates necessary to sustain the synthesis of triacylglycerols (TAGs). Microsomes that contained high activities of the enzymes involved in the synthesis of TAGs (the enzymes of the Kennedy pathway) accumulated TAGs synthesized

in vitro

, resulting in a decrease in their buoyant density. These light membrane fractions could therefore be separated on discontinuous sucrose density gradients from microsomes containing low activities of the enzymes of the Kennedy pathway. Analysis of the microsome fractions by 1H‐NMR spectroscopy showed that the TAGs synthesized in the microsomes

in vitro

were tumbling isotropically in an environment similar to that of the TAGs in oil bodies. Western blot analysis revealed that microsomes which synthesized large amounts of TAGs

in vitro

were also substantially enriched in oleosins. In addition, labelling studies indicated that the oleosins newly synthesized

in vitro

by ‘run‐on' translation of ER‐bound polysomes also localized to light membrane fractions. This indicates that oleosins are specifically enriched in regions of the ER involved in the biogenesis of the oil body.
Molecular characterization of transforming plasmid rearrangements in transgenic rice reveals a recombination hotspot in the CaMV 35S promoter and confirms the predominance of microhomology mediated recombination
Authors: Kohli Ajay , Griffiths Simon , Palacios Natalia , Twyman Richard M. , Vain Philippe , Laurie David A. , Christou Paul 
Published: March 2003

SummaryThe characterization of plasmid‐genomic DNA junctions following plant transformation has established links between DNA double‐strand break repair (DSBR), illegitimate recombination and plasmid DNA integration. The limited information on plasmid–plasmid junctions in plants comes from the dicot species tobacco and Arabidopsis. We analyzed 12 representative transgenic rice lines, carrying a range of transforming plasmid rearrangements, which predominantly reflected microhomology mediated illegitimate recombination involving short complementary patches at the recombining ends. Direct end‐ligation, in the absence of homology between the recombining molecules, occurred only rarely. Filler DNA was found at some of the junctions. Short, purine‐rich tracts were present, either at the junction site or in the immediate flanking regions. Putative DNA topoisomerase I binding sites were clustered around the junctions. Although different regions of the transforming plasmid were involved in plasmid–plasmid recombination, we showed that a 19 bp palindromic sequence, including the TATA box of the CaMV 35S promoter, acted as a recombination hotspot. The purine‐rich half of the palindromic sequence was specifically involved at the recombination junctions. This recombination hotspot is located within the ‘highly recombinogenic’ region of the full‐length CaMV RNA that has been shown to promote viral recombination in dicot plants. Clustering of plasmid recombination events in this highly recombinogenic region, even in the absence of viral enzymes and other cis‐acting elements proves that the plant cellular machinery alone is sufficient to recognize and act on these viral sequences. Our data also show the similarity between mechanisms underlying junction formation in dicot and monocot plants transformed using different procedures.
Matrix attachment regions increase transgene expression levels and stability in transgenic rice plants and their progeny
Authors: Vain Philippe , Worland Barbara , Kohli Ajay , Snape John W. , Christou Paul , Allen George C. , Thompson William F. 
Published: March 2003

SummaryTo investigate the effect of matrix attachment regions (MARs) on transgene expression levels and stability in cereal crops, we generated 83 independent transgenic rice callus lines containing a gusA expression cassette either as a simple expression unit, or flanked with MARs from tobacco (Rb7) or yeast (ARS1). Transgenic rice plants were regenerated from these callus lines and analysed at the structural and expression levels over two generations. In the first generation (T0), both Rb7 and ARS1 MARs significantly increased transgene expression levels. In the populations of plants containing MARs, we observed a significant reduction in the number of non‐expressing lines compared to the population of plants without MARs. However, variation in β‐glucuronidase (GUS) expression levels between independent lines was similar both in the presence and absence of flanking MARs. In the presence of MARs, GUS activity increased in proportion to transgene copy number up to 20 copies, but was generally reduced in lines carrying a higher copy number. In the population of plants without MARs, there was no correlation between expression level and transgene copy number. In the second generation (T1), transgene expression levels were significantly correlated with those of the T0 parents. The Rb7 MARs significantly improved the stability of transgene expression levels over two generations, and therefore appear to offer protection against transgene silencing. Our study shows that the exploitation of MARs may be an important strategy for stabilising transgene expression levels in genetically engineered cereals.