PubMed Health⌕ Search

Biomedical subjects

J Messing

Publications and source records attributed to J Messing.

At least 55 records · Page 3Linked to original sources
PubMed1991

New pUC-derived cloning vectors with different selectable markers and DNA replication origins.

Four new Escherichia coli cloning vectors are described, pUC6S, pUC21, pUK21 and pOK12. These vectors contain a polylinker or multiple cloning site (MCS) with the recognition sequences for 28 restriction enzymes. Plasmids pUC21, pUK21, and pOK12 contain the MCS in the N-terminal end of the lacZ alpha fragment allowing blue/white screening for inserts. To potentially increase the stability of some inserts that may encode toxic proteins, the strength of the lacZ promoter present on these vectors has been reduced. Plasmids pUC6S and pUC21 carry the bla gene encoding ampicillin resistance, while pUK21 and pOK12 contain the gene encoding kanamycin resistance. Plasmid pOK12 carries the replicon from P15A, resulting in a lower copy number pUC-type vector. Plasmid pUC6S carries the ori and bla gene present on all pUC vectors, but does not contain any lac sequences. Plasmids pUC21 and pUK21 contain the M13 intergenic region allowing for the production of plasmid single-stranded DNA. To improve the yield of ss plasmid DNA, two plasmid cis-acting factors that affect yield were also examined: the effect of plasmid-derived transcription across the M13 ori, and the effect of delecting the M13 minus-strand ori from the plasmid.

Base Sequence↗
PubMed1991

Sequence variation between alleles reveals two types of copy correction at the 27-kDa zein locus of maize.

In many inbred lines of maize, two 27-kDa storage protein (zein) genes are found within tandem duplications of 12 kb. Both genes of the duplicated allele from the maize inbred line A188 were sequenced and compared to a similar duplicated allele in another inbred line, W22, and to a single-copy allele in the inbred line W64A. The comparisons reveal interesting patterns in the distribution of sequence changes between these alleles. Differences between the two duplicated alleles that are conserved between the two genes of each allele are found exclusively in the 5' region. In contrast, differences between the individual genes of each allele in the 3' region are conserved between the two alleles. The first case is indicative of an intraallelic copy correction mechanism, whereas the second may result from interallelic copy correction. These may be mediated by gene conversion processes, as previously described for other multigene families.

Alleles↗
PubMed1991

Highly clustered zein gene sequences reveal evolutionary history of the multigene family.

We have determined the nucleotide sequences of zein cDNA clones ZG14, ZG15, and ZG35. The three clones have 95 to 98% homology to the previously published sequence of clone A20, and 84% homology to sequences of the zein subfamily A30. Comparison of all sequences of the A30 and A20 subfamilies highlights the following features: the 5' nontranslated regions are 68 and 57 nucleotides in length for the A20- and A30-like mRNAs, respectively, and contain at least three repeats of the consensus sequence ACGAACAAta/gG; the majority of these genes are highly clustered as judged from pulsed-field gel electrophoresis of high molecular weight maize DNA. Furthermore, we discuss a model for the evolution of the multigene family which stresses the special importance of unequal crossingover and gene conversion in this system.

Base Sequence↗
PubMed1990

The pFF plasmids: cassettes utilising CaMV sequences for expression of foreign genes in plants.

A plant expression cassette was constructed using the cauliflower mosaic virus 35S 5' regulatory region with the enhancer duplicated and the 35S polyadenylation signal. Insertion of a polylinker between the transcription initiation and polyadenylation sites allows for easy cloning of genes. To test the usefulness of the cassette chimeric bacterial genes were prepared. The constructs were introduced into Nicotiana tabacum suspension culture cells by the particle bombardment process. Expression of the beta-glucuronidase reporter gene was verified by histochemical staining. Stable kanamycin and hygromycin resistant transgenic lines were obtained after introduction of chimeric genes encoding the enzymes neomycin phosphotransferase and hygromycin B phosphotransferase, respectively. The number of stable transformants was approximately 2% of the cells that transiently expressed the beta-glucuronidase reporter gene.

Blotting, Southern↗
PubMed1990

A somatic gene rearrangement contributing to genetic diversity in maize.

We have discovered a somatic genomic rearrangement that occurs at high frequency at a duplicated zein locus in certain cultures of the maize inbred line A188. The rearranged allele arises from the duplication by a two-step process involving a homologous recombination and a second event, which may be a deletion, inversion, or insertion; both steps always occur together. The frequency of rearrangement is lower in homozygous states of the parental allele than in heterozygotes. In both cases, the rearrangement is shown to be mitotic. The rearranged product can be transmitted through meiosis, providing another mechanism for genome evolution in higher eukaryotes.

Base Sequence↗
PubMed1988

Isolation and sequence of a gene encoding a methionine-rich 10-kDa zein protein from maize.

We have isolated the gene encoding a methionine-rich 10-kDa zein protein from a lambda EMBL3 maize genomic 'mini' library of the inbred line BSSS-53 and determined its nucleotide sequence. The sequence matches perfectly with a cDNA clone from the inbred line W22 (which has the same restriction fragment length polymorphism as many inbred lines tested) indicating that we have isolated a functional storage protein gene that is very conserved in maize. This comparison also excludes any splicing of any precursor mRNA and therefore any presence of introns. A number of potential regulatory sequences have been located in the flanking regions. The 10-kDa-zein gene represents the last size class in the zein multigene family to be characterized. Its structure allows us now to re-examine the relationship of all the zein proteins and also to compare the structure of a new class of storage proteins that are rich in methionine, an essential amino acid in livestock fodder.

Amino Acid Sequence↗
PubMed1988

Maize glutamine synthetase cDNAs: isolation by direct genetic selection in Escherichia coli.

Maize glutamine synthetase cDNA clones were isolated by genetic selection for functional rescue of an Escherichia coli delta glnA mutant growing on medium lacking glutamine. The Black Mexican Sweet cDNA library used in this study was constructed in pUC13 such that cDNA sense strands were transcribed under the control of the lac promoter. E. coli delta glnA cells were transformed with cDNA library plasmid DNA, grown briefly in rich medium to allow phenotypic expression of the cDNAs and the pUC13 ampr gene, and challenged to grow on agar medium lacking glutamine. Large numbers of glutamine synthetase cDNA clones have been identified in individual 150-mm Petri dishes; all characterized cDNA clones carry complete coding sequences. Two cDNAs identical except for different 5' and 3' termini have been sequenced. The major open reading frame predicts a protein with an amino acid sequence that exhibits striking similarity to the amino acid sequences of the predicted products of previously sequenced eukaryotic glutamine synthetase cDNAs and genes. In addition, the maize glutamine synthetase cDNAs were shown to contain a 5' mini-ORF of 29 codons separated by 37 nucleotide pairs from the major ORF. This mini-ORF was shown not to be essential for the functional rescue of the E. coli delta glnA mutant. Expression of the cDNAs in E. coli is presumed to be due to the function of a polycistronic hybrid lac messenger RNA or translational fusions encoded by the pUC plasmids. Proteins of the expected sizes encoded by two different pUC clones were shown to react with antibodies to tobacco glutamine synthetase.

Amino Acid Sequence↗
PubMed1985

Improved M13 phage cloning vectors and host strains: nucleotide sequences of the M13mp18 and pUC19 vectors.

Three kinds of improvements have been introduced into the M13-based cloning systems. (1) New Escherichia coli host strains have been constructed for the E. coli bacteriophage M13 and the high-copy-number pUC-plasmid cloning vectors. Mutations introduced into these strains improve cloning of unmodified DNA and of repetitive sequences. A new suppressorless strain facilitates the cloning of selected recombinants. (2) The complete nucleotide sequences of the M13mp and pUC vectors have been compiled from a number of sources, including the sequencing of selected segments. The M13mp18 sequence is revised to include the G-to-T substitution in its gene II at position 6 125 bp (in M13) or 6967 bp in M13mp18. (3) M13 clones suitable for sequencing have been obtained by a new method of generating unidirectional progressive deletions from the polycloning site using exonucleases HI and VII.

Base Sequence↗
PubMed1985

The nucleotide sequence of a mitochondrial replicon from maize.

The 1913-bp maize mitochondrial (mt) plasmid was isolated from a suspension culture of a Black Mexican Sweet maize strain, cloned into M13mp vectors, and sequenced by a unidirectional progressive deletion method. The 1.9-kb extrachromosomal double-stranded circular DNA plasmid was found to contain regions of sequence which in other systems are known to be part of origins of replication (ori). This plasmid could be used as a carrier for chimeric genes and a molecular probe for replication.

Amino Acid Sequence↗
PubMed1984

The nucleotide sequence of the maize controlling element Activator.

We have determined the nucleotide sequence of the transposable maize controlling element Activator (Ac). The Ac element is 4563 bp long and has an imperfect terminal repetition of 11 bp. The element contains two open reading frames (ORF) encoding polypeptides of 839 and 210 amino acids. Evidence derived from structural analysis of a closely related, but transposition-defective Dissociation (Ds) element indicates that the large ORF is the structural gene for a trans-acting function required for transposition. The two ORFs diverge from a short intergenic region which contains characteristic eucaryotic transcription initiation sequences.

Amino Acid Sequence↗
PubMed1984

Nucleotide sequence analysis of a zein genomic clone with a short open reading frame.

The nucleotide sequence of the zein genomic clone (W22)Z7 and its flanking sequences from the W22 inbred line of maize is reported. The sequence is 1587 bp long and contains 444 bp of 5' noncoding sequence and 342 bp of 3' noncoding sequence. The Z7 sequence belongs to a large complex multigene family and is a member of the B49 subfamily. It is 86% homologous to other known sequences from the same subfamily, but contains four in-frame termination codons caused by single base changes. Its flanking regions contain the usual eukaryotic transcriptional signals.

Base Sequence↗
PubMed1984

Primary structure of the Escherichia coli ribonucleoside diphosphate reductase operon.

The nucleotide sequence of the Escherichia coli K-12 DNA comprising the operon for the structural genes of the subunits of ribonucleotide diphosphate reductase has been determined. The DNA sequenced maps at 48.5 minutes on the E. coli chromosome and includes a total length of 8557 nucleotides. An open reading frame between nucleotides 3506 and 5834, encoding a 776-amino acid polypeptide chain with a molecular weight of 87,532, has been identified as the nrdA gene. An open reading frame between nucleotides 6012 and 7139, encoding a 375-amino acid polypeptide with a molecular weight of 43,466, has been identified as the nrdB gene. The sequences reveal not only the primary structures for both subunits, but also some interesting aspects of potential regulatory sites.

Amino Acid Sequence↗
PubMed1984

Cloning and sequencing of the ribosomal RNA genes in maize: the 17S region.

The maize genes for the 17S, 5.8S, and 26S ribosomal RNAs (rRNAs) are located on chromosome 6 and consist of 9-kb sequences repeated about 5,000-10,000 times per 2C. One of these sequences was isolated from a lambda library containing maize Eco RI genomic segments. The sequence of the small-subunit (17S) RNA was determined using the M13 shotgun-dideoxy sequencing approach. The maize sequence was compared with nuclear rRNAs from yeast, Xenopus, and rat. Using these sequences, it is possible to identify tentatively the start and the end points of the sequence of the maize nuclear small subunit rRNA. This RNA has a length of 1809 nucleotides. The alignment of all four sequences for maximal homology allows us to identify regions within the rRNA that have been conserved during eukaryotic evolution.

Animals↗
PubMed1983

Sequence analysis of zein cDNAs obtained by an efficient mRNA cloning method.

A cDNA library was generated from mRNA isolated from the developing endosperm of W22 maize inbred. cDNA clones for zein, the maize storage protein family, were isolated and analyzed by DNA sequencing. The DNA sequences of four clones containing cDNA copies of mRNAs belonging to one zein subfamily were determined. The data support the following conclusions: a) genes encoding the larger of the two zein species contain eleven instead of nine repeat units within the coding sequence of the gene; b) transcription can be terminated at either of the two polyadenlation signals and c) transcription starts 31 basepairs downstream from the first T in the TATA box. To facilitate this analysis a new method for the construction of cDNA libraries was developed. The mRNA was annealed to linearized and oligo-dT tailed pUC9 plasmid DNA, which then primed synthesis of the first strand of the cDNA. Oligo-dG tails were added to the cDNA-plasmid molecules, which were then centrifuged through an alkaline sucrose gradient. The gradient step removed small molecules and separated the two cDNAs which were formerly attached to the same double stranded plasmid molecule. An excess of oligo-dC tailed denatured pUC9 DNA was added and the DNA was renatured under conditions that favor the circularization of monomers by the oligo-dC and oligo-dG tails. The oligo-dC tail served as primer for the synthesis of the second strand of the cDNA. The library was screened by colony hybridization using 32P-labelled cDNA and DNA from genomic zein clones as probes. We obtained 20,000 clones hybridizing total cDNA starting with 1 microgram of plasmid DNA and 1 microgram of mRNA.

Amino Acid Sequence↗