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M Bevan

Publications and source records attributed to M Bevan.

At least 19 recordsLinked to original sources
PubMed2001

Sequence and analysis of the Arabidopsis genome.

The comprehensive analysis of the genome sequence of the plant Arabidopsis thaliana has been completed recently. The genome sequence and associated analyses provide the foundations for rapid progress in many fields of plant research, such as the exploitation of genetic variation in Arabidopsis ecotypes, the assessment of the transcriptome and proteome, and the association of genome changes at the sequence level with evolutionary processes. Nevertheless, genome sequencing and analysis are only the first steps towards a new plant biology. Much remains to be done to refine the analysis of encoded genes, to define the functions of encoded proteins systematically, and to establish new generations of databases to capture and relate diverse data sets generated in widely distributed laboratories.

Arabidopsis↗
PubMed2001

Renal disease in older people.

There has been a significant rise in the incidence of renal failure in older people. This article gives an overview of possible causes and treatment.

Aged↗
PubMed2000

Transactivation of a target gene through feedforward loop activation in plants.

The expression of many genes encoding transcriptional activators in prokaryotes and eukaryotes is upregulated through positive feedback activation. During positive feedback activation, a transcriptional activator binds to its own promoter and thus increases its own expression as well as the expression of its target genes. In the simplest case, increased levels of the transcriptional activator can be directly correlated with increased expression of its target genes. In this study, we present a gene expression system, designated feedforward loop (FFL) system, which makes use of this kind of positive feedback regulation for the expression of plant transgenes. We show in transient and stable transformation experiments that such a system is functional and that it can be used to obtain high level gene expression in plants. We also provide evidence that the transgene is ubiquitously expressed when using the FFL system. Finally, we discuss the possibilities of using FFL gene expression systems for applications in plant molecular genetics and biotechnology.

Agrobacterium tumefaciens↗
PubMed1999

Genetic definition and sequence analysis of Arabidopsis centromeres.

High-precision genetic mapping was used to define the regions that contain centromere functions on each natural chromosome in Arabidopsis thaliana. These regions exhibited dramatic recombinational repression and contained complex DNA surrounding large arrays of 180-base pair repeats. Unexpectedly, the DNA within the centromeres was not merely structural but also encoded several expressed genes. The regions flanking the centromeres were densely populated by repetitive elements yet experienced normal levels of recombination. The genetically defined centromeres were well conserved among Arabidopsis ecotypes but displayed limited sequence homology between different chromosomes, excluding repetitive DNA. This investigation provides a platform for dissecting the role of individual sequences in centromeres in higher eukaryotes.

Arabidopsis↗
PubMed1999

Clearing a path through the jungle: progress in Arabidopsis genomics.

Progress in sequencing the genome of the model plant Arabidopsis is reviewed. The resulting analysis of the sequence indicates an information-rich genome that is being tackled by a variety of high-throughput approaches aimed at understanding the functions of plant genes. The information derived from these systematic studies is providing important new knowledge of biological processes found uniquely in plants for comparison with that obtained in other multicellular organisms.

Arabidopsis↗
PubMed1999

The small, the large and the wild: the value of comparison in plant genomics.

Studies of the model plant Arabidopsis are providing knowledge about the function of plant genes with an unprecedented clarity and quantity. A major challenge now is to apply this new information to the improvement of crop plants in a systematic manner. Sequence comparisons between Arabidopsis and rice can define potential functional relationships, and conserved gene order among cereals can then be used to ascribe functions to genes in many cereals.

Agriculture↗
PubMed1999

Transcription activation mediated by the bZIP factor SPA on the endosperm box is modulated by ESBF-1 in vitro.

A modified in vitro transcription system has been used to study the function of the cloned bZIP transcription factor SPA and the binding activity ESBF I in activating transcription from the bifactorial endosperm box region of the wheat prolamin LMWG-1D1 gene. Recombinant SPA expressed in Escherichia coli activated transcription from the endosperm box motif, and this was dependent upon the binding of the nuclear protein ESBF I. ESBF I did not activate transcription independently, but potentiated SPA-mediated transcriptional activation. ESBF I is likely to be the equivalent of, or contain the recently characterised DOF class of, Zn-finger protein called WPBF. These data provide new information about the interplay of members of the bZIP and DOF transcription factor families in regulating expression from bifactorial sites found in a variety of plant promoters.

Journal Article↗
PubMed1998

Analysis of 1.9 Mb of contiguous sequence from chromosome 4 of Arabidopsis thaliana.

The plant Arabidopsis thaliana (Arabidopsis) has become an important model species for the study of many aspects of plant biology. The relatively small size of the nuclear genome and the availability of extensive physical maps of the five chromosomes provide a feasible basis for initiating sequencing of the five chromosomes. The YAC (yeast artificial chromosome)-based physical map of chromosome 4 was used to construct a sequence-ready map of cosmid and BAC (bacterial artificial chromosome) clones covering a 1.9-megabase (Mb) contiguous region, and the sequence of this region is reported here. Analysis of the sequence revealed an average gene density of one gene every 4.8 kilobases (kb), and 54% of the predicted genes had significant similarity to known genes. Other interesting features were found, such as the sequence of a disease-resistance gene locus, the distribution of retroelements, the frequent occurrence of clustered gene families, and the sequence of several classes of genes not previously encountered in plants.

Arabidopsis↗
PubMed1998

Towards functional characterisation of the members of the R2R3-MYB gene family from Arabidopsis thaliana.

Transcription factors containing a conserved DNA-binding domain similar to that of the proto-oncogene c-myb have been identified in nearly all eukaryotes. MYB-related proteins from plants generally contain two related helix-turn-helix motifs, the R2 and R3 repeats. It was estimated that Arabidopsis thaliana contains more than 100 R2R3-MYB genes. The few cases where functional data are available suggest an important role of these genes in the regulation of secondary metabolism, the control of cell shape, disease resistance, and hormone responses. To determine the full regulatory potential of this large family of regulatory genes, a systematic search for the function of all genes of this family was initiated. Sequence data for more than 90 different A. thaliana R2R3-MYB genes have been obtained. Sequence comparison revealed conserved amino acid motifs shared by subgroups of R2R3-MYB genes in addition to the characteristic DNA-binding domain. No significant clustering of the genes was detected, although they are not uniformly distributed throughout the A. thaliana genome.

Amino Acid Sequence↗
PubMed1996

Tissue-specific expression of the PAL3 promoter requires the interaction of two conserved cis sequences.

The bean PAL2 and PAL3 promoters confer expression in overlapping sets of tissue types in transgenic tobacco. The PAL3 promoter contains motifs that resemble two AC cis elements which are required for tissue-specific expression of the PAL2 promoter. The functions of these motifs in the PAL3 promoter were determined by analysis of mutated PAL3 promoter-GUS constructs in transgenic tobacco. This revealed that the AC motifs are necessary for tissue-specific expression of the PAL3 promoter. Therefore, a key role is indicated for AC elements, which are Myb-protein binding sites, in regulating tissue-specific expression of the bean PAL gene family.

Base Sequence↗
PubMed1995

Expression of a flower-specific Myb protein in leaf cells using a viral vector causes ectopic activation of a target promoter.

The promoter of the bean PAL2 gene (encoding phenylalanine ammonia-lyase; EC 4.3.1.5) is a model for studies of tissue-restricted gene expression in plants. Petal epidermis is one of the tissues in which this promoter is activated in tobacco. Previous work suggested that a major factor establishing the pattern of PAL2 expression in tobacco petals is the tissue distribution of a protein closely related to Myb305, which is a Myb-like transcriptional activator from snapdragon. In the present work, we show that Myb305 expression in tobacco leaves causes ectopic activation of the PAL2 promoter. To achieve Myb305 expression in planta, a viral expression vector was used. This approach combines the utility of transient assays with the possibility of direct biochemical detection of the introduced factor and may have wider application for studying the function of plant transcription factors.

Base Sequence↗
PubMed1995

Two classes of cis sequences contribute to tissue-specific expression of a PAL2 promoter in transgenic tobacco.

Genes encoding phenylalanine ammonia-lyase (PAL) are expressed in a complex pattern during plant development and in response to light, pathogen ingress, mechanical damage and other stresses. Analysis of the promoter of the bean PAL2 gene in transgenic tobacco has shown that some regions responsible for developmental expression are functionally compensatory. The minimum sequence containing all cis sequences necessary for developmental patterns of expression is within -254 bp of the transcription start site. Footprinting and electrophoretic mobility shift assay studies of this region revealed potential cis sequences which coincided with the functional domains defined by small deletions and promoter fusions. Mutations in these potential cis sequences in the context of the minimal -254 bp promoter altered tissue-specific expression patterns, confirming the importance of these sequences for expression in vivo. A functional model for the promoter is presented which predicts that three AC-elements, which are possible Myb protein binding sites, together with a G-box, interact to direct the complex patterns of tissue-specific expression observed.

Base Sequence↗