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A Durr

Publications and source records attributed to A Durr.

At least 37 records · Page 2Linked to original sources
PubMed1997

Characterization of a tobacco extensin gene and regulation of its gene family in healthy plants and under various stress conditions.

A genomic clone (Ext 1.4) encoding an extensin was isolated from a Nicotiana tabacum genomic library. The encoded polypeptide showed features characteristic of extensins such as Ser-(Pro)4 repeats and a high content in Tyr and Lys residues. The presence of one Tyr-Leu-Tyr-Lys motif suggests the possibility for one intramolecular isodityrosine cross-link whereas numerous Val-Tyr-Lys motifs may participate in intermolecular cross-links. This extensin appears to be close to an extensin already characterized in N. tabacum but very different from the Ext 1.2 extensin of N. sylvestris. The analysis of genomic DNA gel blots using probes spanning different parts of the gene showed that the Ext 1.4 gene belongs to a complex multigene family having one member originating from N. sylvestris and three members from N. tomentosiformis. The Ext 1.4 specific probe found a 1.4 kb mRNA in stems, roots, ovaries and germinating seeds of healthy plants. The Ext 1.4 gene family is strongly induced in actively dividing cell suspension cultures and after wounding of leaves or stems in conditions where root formation occurs. On the contrary, it is not induced in leaves in response to a hypersensitive reaction to a viral infection or after elicitor treatment.

Amino Acid Sequence↗
PubMed1996

Parasympathetic activity in Friedrich's ataxia.

We compared 19 patients with Friedreich's ataxia, a progressive hereditary neuromuscular disorder, with 19 healthy age-matched subjects. During nighttime, patients had shorter mean RR and decreased heart rate variability parameters related to parasympathetic activity than healthy subjects, whereas no difference occurred during daytime.

Adult↗
PubMed1996

Genetic fitness in Huntington's Disease and Spinocerebellar Ataxia 1: a population genetics model for CAG repeat expansions.

An analysis of genetic fitness was performed in Huntington's Disease (HD) and Spinocerebellar Ataxia 1 (SCA1) families. Two partially overlapping samples were used: clinically defined HD and SCA1 patients from families ascertained in definite geographical areas, and molecularly typed carriers of HD and SCA1 mutations (CAG trinucleotide expansions). In both cases, a control group of normal relatives was used. HD and SCA1 patients born before 1915-20 had more children than normal controls. Carriers of HD and SCA1 mutations, all in the low/medium expansion range (37-49 and 47-54 CAG repeats respectively), had a higher number of children than controls up to more recent times (1935-1950). The reproduction of heterozygotes for large expansions could be analysed only in subjects born after 1950 and provided indirect evidence of a lower than normal number of children. The above results fit a model based on a differential fitness according to the degree of expansion. Such a model predicts that 1) up to relatively recently the frequency of alleles in the low/medium range has been maintained or even increased by the increased fitness of their carriers, as well as by new mutations, and 2) the frequency of large expansions, part of which are lost at each generation, is maintained through further expansions of alleles in the low/medium expansion range. The implications of such a model on linkage disequilibrium and the possible spread of these diseases in future generations are discussed.

Age of Onset↗
PubMed1995

A novel wound-inducible extensin gene is expressed early in newly isolated protoplasts of Nicotiana sylvestris.

A cDNA clone (6PExt 1.2) encoding a novel extensin was isolated from a cDNA library made from 6 h old mesophyll protoplasts of Nicotiana sylvestris. The screening was performed with a heterologous probe from carrot. The encoded polypeptide showed features characteristic of hydroxyproline-rich glycoproteins such as Ser-(Pro)4 repeats and a high content in Tyr and Lys residues. The presence of four Tyr-X-Tyr-Lys motifs suggests the possibility for intramolecular isodityrosine cross-links whereas three Val-Tyr-Lys motifs may participate in intermolecular cross-links. The analysis of genomic DNA gel blots using both the N. sylvestris and the carrot clones as probes showed that the 6PExt 1.2 gene belongs to a complex multigene family encoding extensin and extensin-related polypeptides in N. sylvestris as well as in related Nicotianeae including a laboratory hybrid. This was confirmed by the analysis of RNA gel blots: a set of mRNAs ranging in size from 0.3 kb to 3.5 kb was found by the carrot extensin probe. The 6PExt 1.2 probe found a 1.2 kb mRNA in protoplasts and in wounded tissues as well as a 0.9 kb mRNA which seemed to be stem-specific. The gene encoding 6PExt 1.2 was induced by wounding in protoplasts, in leaf strips and after Agrobacterium tumefaciens infection of stems.

Amino Acid Sequence↗
PubMed1995

The CIC library: a large insert YAC library for genome mapping in Arabidopsis thaliana.

A new Arabidopsis thaliana (ecotype Columbia) genomic library has been constructed in Yeast Artificial Chromosomes: the CIC library (for CEPH, INRA and CNRS). Optimization of plant culture conditions and protoplast preparation allowed the recovery of large amounts of viable protoplasts. Mechanical shearing of DNA was minimized by isolation of DNA from protoplasts embedded in agarose. Cloning of large inserts was favored by including two successive size fractionation steps (after partial EcoRI digestion and after ligation with the vector arms), which selected DNA fragments larger than 350 kb. The library consists of 1152 clones with an average insert size of 420 kb. Clones carrying chloroplast DNA and various nuclear repeated sequences have been identified. Twenty-one per cent of the clones are found to contain chloroplast DNA. Therefore, the library represents around four nuclear genome equivalents. The clones containing 5S rDNA genes, 18S-25S rDNA sequences and the 180 bp paracentromeric repeated element account for 3.6%, 8.9% and 5.8%, respectively. Only one clone was found to carry the 160 bp paracentromeric repeated element. Given the smaller size of clones carrying Arabidopsis repeated DNA, the average size of remaining clones is around 480 kb. The library was screened by PCR amplification using pairs of primers corresponding to sequences dispersed in the genome. Seventy out of 76 pairs of primers identified from one to seven YAC clones. Thus at least 92% of the genome is represented in the CIC library. The survey of the library for clones containing unlinked DNA sequences indicates that the proportion of chimeric clones is lower than 10%.

Arabidopsis↗
PubMed1995

Vertebral hyperostosis and diabetes mellitus: a case-control study.

OBJECTIVE: To compare glucose metabolism in patients with vertebral hyperostosis (VH), with that in control patients. METHODS: We studied 50 patients aged 60 years or more who had VH according to Resnick's criteria, and 50 control patients without VH, matched for sex, age, weight and height. Plasma glucose was evaluated before and 120 minutes after ingestion of 75 g glucose. World Health Organisation criteria for diabetes mellitus (DM) were used. Radiographs of the pelvis and thoracic and lumbar spine were performed and read blind by two physicians. RESULTS: Statistical analysis showed no difference between cases and control patients for prevalence of DM, and plasma glucose at 0 and 120 minutes. CONCLUSION: These data suggest that glucoregulation in patients with VH does not differ from that in matched controls.

Aged↗
PubMed1994

Differential expression of several E2-type ubiquitin carrier protein genes at different developmental stages in Arabidopsis thaliana and Nicotiana sylvestris.

We characterized three genes encoding different E2-type ubiquitin carrier proteins involved in the ubiquitin-mediated proteolytic pathway: UbcAt3 shows homologies to the yeast CDC34 gene and Ub-cAt4a and UbcAt4b are two different genes homologous to the Ubc1/4/5 subfamily in yeast. Their accumulation was analysed and compared with that of the different families encoding polyubiquitins, as well as the monoubiquitin fusion protein, which is considered as a marker for cell division, during various developmental stages including G0/S transition and senescence of higher plant cells. Our results imply that these Ubc genes are under the control of complex mechanisms, and are differentially regulated, but not necessarily co-regulated with ubiquitin genes. Even the closely related UbcAt4a and UbcAt4b genes of the same multigene subfamily are controlled by distinct regulatory mechanisms.

Adaptation, Physiological↗
PubMed1993

Why are quiescent mesophyll protoplasts from Nicotiana sylvestris able to re-enter into the cell cycle and re-initiate a mitotic activity?

Mesophyll protoplasts of Nicotiana sylvestris incubated in an adequate culture medium re-enter very rapidly into the cell cycle and divide. The transition G0/G1 is accompanied by a complete reversion of the program of gene expression. The program of the photosynthetic differentiated mesophyll cell is abolished whereas a new multipartite program of a highly stressed but ready-to-divide cell is established. Some genes encode proteins which structure suggests they may play key roles in these events. Most of the induced genes are under multiple controls: stress and/or development. Stress response and cellular re-organization might thus be closely related events that cannot be dissociated. It is probable that the re-entry of a protoplast into the cell cycle, ie the initial step of totipotency, closely depends on the coordinated activation of a set of genes that share common regulatory mechanisms.

Cell Cycle↗
PubMed1993

Genetic heterogeneity of autosomal dominant cerebellar ataxia type 1: clinical and genetic analysis of 10 French families.

We performed linkage analysis between the gene responsible for spinal cerebellar ataxia 1 (SCA1) and the highly polymorphic chromosome 6 locus, D6S89, in 10 French families with autosomal dominant cerebellar ataxia (ADCA) type 1. These families were clinically indistinguishable except for one family with loss of hearing and vision. Very close linkage was observed in four families, with no evidence of recombination between SCA1 and D6S89. Linkage with D6S89 was excluded in the six others, thus demonstrating genetic heterogeneity for ADCA type 1. The D6S89 marker, which is very closely linked to the disease locus, can be used to identify SCA1 families and will lead to predictive testing.

Adult↗
PubMed1992

Isolation and characterization of a cDNA encoding a 3-hydroxy-3-methylglutaryl coenzyme A reductase from Nicotiana sylvestris.

A cDNA library from freshly isolated mesophyll protoplasts of Nicotiana sylvestris was differentially screened using cDNAs from leaves, leaf strips submitted to the same stress as protoplasts during the isolation procedure, and cell suspension cultures. One of the selected clones (6P2) was found to encode a putative polypeptide highly homologous to previously characterized 3-hydroxy-3-methylglutaryl coenzyme A reductases. The C-terminal region of the polypeptide was highly conserved whereas its N-terminal region including the trans-membrane domains and the linker was more variable. Apart from protoplasts, the 6P2 gene was found to be expressed in apexes, anthers, roots, and in stressed leaf strips after 24 h of culture, during the hypersensitive reaction to viral infection and after HgCl2 treatment. This pattern of expression is consistent with a role in plant defence mechanisms.

Amino Acid Sequence↗
PubMed1992

Ubiquitin genes are differentially regulated in protoplast-derived cultures of Nicotiana sylvestris and in response to various stresses.

Four ubiquitin mRNA size classes were found to be differentially regulated in mesophyll protoplast-derived cultures of Nicotiana sylvestris. Three mRNA families of 1.9, 1.6 and 1.35 kb were expressed as soon as protoplasts were isolated. The 1.9 and 1.6 kb size classes were transiently expressed during the first hours of culture, whereas the level of expression of the 1.35 kb size class was maintained as long as cells kept dividing. A 0.7 kb mRNA size class started to be expressed just before the first divisions were observed. cDNAs corresponding to each of these families were isolated from a 6-h-old protoplast cDNA library and characterized. The 1.9, 1.6 and 1.35 kb mRNAs thus encode 7- or more, 6- and 5-mers, respectively, of ubiquitin whereas the 0.7 kb mRNAs encode a monomer of ubiquitin fused to a carboxyl extension protein of 52 amino acids. The expression of ubiquitin genes was studied, using probes specific for each of these transcript families, during protoplast culture and, for comparison, after various stresses including heat shock, HgCl2 treatment, a viral infection giving rise to a hypersensitive reaction, and an Agrobacterium tumefaciens infection which resulted in tumour formation. The 1.9 and 1.6 kb mRNA size classes were found to be stress-regulated, the 0.7 kb mRNA size class developmentally regulated and the 1.35 kb size class both stress- and developmentally regulated.

Amino Acid Sequence↗
PubMed1992

Isolation and characterization of a plant cDNA showing homology to animal glutathione peroxidases.

A cDNA library from freshly isolated protoplasts was differentially screened using cDNAs from mesophyll cells, stressed leaf strips and cell suspension cultures. One of the selected clones, 6P229, turned out to encode a putative polypeptide showing homology to the btuE periplasmic protein of Escherichia coli and to animal selenium-dependent glutathione peroxidases. A major difference was that the putative selenocysteine in the active site was not encoded by the termination codon TGA. The 6P229 gene was found to be expressed in germinating seeds, in apex and in flowers, as well as in stressed tissues. This pattern of expression would be consistent with a key role in cellular metabolism such as defense against oxidative stresses.

Amino Acid Sequence↗
PubMed1992

Characterization of genes expressed in mesophyll protoplasts of Nicotiana sylvestris before the re-initiation of the DNA replicational activity.

To decipher the early events preceding the re-entry of somatic cells into the cell cycle, we constructed a cDNA library from 6-h-old protoplasts of Nicotiana sylvestris. We characterized three mRNAs, via their cDNAs, that accumulate at very high levels 6 h after the beginning of the culture. Two of them could be identified by comparison of the deduced amino acid sequence to databanks. 6P10 is a novel type I trypsin inhibitor, which has the peculiarity of being devoid of the pro-sequence peptide described to be essential for transport to the vacuole. 6P73 is a novel, moderately anionic peroxidase. 6P50 belongs to a gene family not yet identified. These genes are highly expressed in protoplasts at the beginning of the culture and moderately in roots, but are neither expressed in response to chemical treatment, heat shock, pathogen attacks nor during tumor induction. These findings suggest that the activation of these genes corresponds not only to a specific adaptation of protoplasts to the new environment but also, since their level of expression decreases at the onset of division, to a sequence of events connected with the establishment of the new program of gene expression of the dividing cell.

Agrobacterium tumefaciens↗
PubMed1991

Genes encoding the small subunit of RUBISCO belong to two highly conserved subfamilies in Nicotianeae.

The sequences of seven complementary DNAs or genes encoding the small subunit (SSU) of ribulose-1,5-bisphosphate carboxylase oxygenase (RUBISCO) in several Nicotianeae were examined. Two new SSU genes isolated from Nicotiana sylvestris were included. Both sequence comparisons and Southern analyses with specific probes reveal that SSU genes fall into two homogeneous subfamilies that are highly conserved in Nicotianeae and are also present in other Solanaceae. Additional criteria such as number of introns and level of expression fitted to this classification. Homogeneity must have been maintained by gene conversion and/or an unusually high fidelity of DNA replication, whereas traces of slippage-stranded DNA mispairing and/or transposition probably explain local changes. Taken as a whole, these results show that the divergence between the two subfamilies predated the divergence between genera inside the Solanaceae, but that Nicotianeae retained the most simple SSU gene family structure.

Base Sequence↗
PubMed1990

Is ubiquitin involved in the dedifferentiation of higher plant cells?

Transformation of a mesophyll cell into a viable protoplast that is able to re-enter the cell cycle, divide and further differentiate into organs, is accompanied by a very rapid and important increase in ubiquitin gene expression. Three major size classes of ubiquitin mRNA transcripts were observed in protoplasts as soon as they were isolated and incubated in their culture medium. The 1.6 kb mRNAs were expressed in response to the stress caused by the isolation procedure. They decreased after a few hours of incubation in the culture medium. The 1.9 kb and the 1.3 kb mRNAs enhanced in protoplasts were also observed in young leaves and in actively dividing cells: they appeared to be developmental-stage specific. They are not expressed in response to the stress, but may be considered to be part of the dedifferentiation program induced in protoplasts. These results suggest, as the enhancement of ubiquitin gene expression coincides with the dramatic changes in gene expression observed in protoplasts, that ubiquitin may play a fundamental role in the process of cellular dedifferentiation.

Blotting, Northern↗
PubMed1987

Absence of some truncated genes in the amphidiploid Nicotiana tabacum.

As an initial step towards understanding how a multigene family evolves after an interspecific hybridization and subsequent chromosomal doubling, genomic Southern blots of three related species were compared: Nicotiana tabacum (the progeny), and Nicotiana sylvestris and Nicotiana tomentosiformis (the progenitors). Genomic restriction fragments generated by two endonucleases were hybridized with a cDNA of the small subunit of ribulose bisphosphate carboxylase from N. sylvestris. The restriction pattern of the DNA of the progenitors revealed considerable polymorphism of restriction-fragment lengths. All the fragments in N. tabacum, except one, have a corresponding fragment in one of the progenitors. Some fragments present in the parents were absent from the progeny: they may correspond to truncated genes consisting of only part of the 3' portion of the gene.

DNA Restriction Enzymes↗