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T Candresse

Publications and source records attributed to T Candresse.

70 records · Page 4Linked to original sources
PubMed1990

Construction of novel viroid chimeras containing portions of tomato apical stunt and citrus exocortis viroids.

Several novel tomato apical stunt viroid (TASV) recombinants were isolated after inoculation of tomato seedlings with monomeric viroid cDNAs. Two intraspecific recombinants were constructed by exchanging the left and right sides of the closely related Ivory Coast and Indonesian strains of TASV, and a third, interspecific, recombinant was constructed by similar manipulations involving TASV and citrus exocortis viroid (CEV) cDNAs. Characterization of these TASV recombinants by RNA protection assays and nucleotide sequence analysis of polymerase chain reaction-amplified cDNAs revealed no evidence for sequence instability. The symptoms induced by replication of the CEV-TASV chimera in tomato were milder than those induced by either TASV or the TASV chimeras and resembled those induced by the CEV isolate which provided its pathogenicity domain.

Base Sequence↗
PubMed1990

Nucleotide sequence and genomic organization of apple chlorotic leaf spot closterovirus.

The nucleotide sequence of Apple chlorotic leaf spot closterovirus (ACLSV) genomic RNA has been determined from cDNA clones. It is 7555 nucleotides in length excluding the 3' terminal poly(A) tail and contains three putative open reading frames capable of encoding proteins of 216.5, 50, and 28 kDa. ACLSV RNA has untranslated regions of 151 and 190 nucleotides at its 5' and 3' termini, respectively. The 216.5-kDa ORF encodes a protein which contains the conserved "signature" sequences and has significant homology with the proteins suspected to be involved in viral RNA replication of members of the "Sindbis-like" supergroup of viruses. On the basis of distant homologies with viral movement proteins (M proteins), the 50-kDa ORF is suspected to encode a protein responsible for virus cell-to-cell spread. The 28-kDa ORF contains, in frame, a smaller 21.5-kDa ORF encoding the coat protein of ACLSV. These results show that ACLSV and probably at least the subgroup A of closteroviruses should be regarded as members of the "Sindbis-like" supergroup of RNA viruses.

Amino Acid Sequence↗
PubMed1990

Dot hybridization detection of plum pox virus using 32P-labeled RNA probes representing non-structural viral protein genes.

A cDNA library covering the complete genome of plum pox virus strain D (PPV D) has been obtained, and an endonuclease restriction map derived from it. This map was superposed on the PPV genomic organisation map, established for a nonaphid transmissible strain of PPV (Maiss et al., 1989). This allowed us to select seven probes, corresponding to different regions on the PPV genome. These probes were tested in a dot-blot hybridization assay for the detection of PPV. Probes of various lengths (0.25 to 1.5 kb) were tested and those measuring at least 0.8 kb (4 of the 7 probes selected) proved to be the most sensitive. The detection limit was of about 5 pg of purified virus per assay. Probes representing non-structural viral protein genes were equally sensitive in detecting both serotypes D and M of PPV. The previously described probe pBPPV1 (Varveri et al., 1988), covering the coat protein gene of strain D, was less sensitive, when compared to the above probes, in detecting heterologous strains of PPV. The polyvalence of probes transcribed from non-structural viral protein genes was confirmed by screening isolates of PPV, collected in infected orchards in several Mediterranean countries.

Autoradiography↗
PubMed1989

Nucleotide sequence of Hungarian grapevine chrome mosaic nepovirus RNA1.

The nucleotide sequence of the RNA1 of hungarian grapevine chrome mosaic virus, a nepovirus very closely related to tomato black ring virus, has been determined from cDNA clones. It is 7212 nucleotides in length excluding the 3' terminal poly(A) tail and contains a large open reading frame extending from nucleotides 216 to 6971. The presumably encoded polyprotein is 2252 amino acids in length with a molecular weight of 250 kDa. The primary structure of the polyprotein was compared with that of other viral polyproteins, revealing the same general genetic organization as that of other picorna-like viruses (comoviruses, potyviruses and picornaviruses), except that an additional protein is suspected to occupy the N-terminus of the polyprotein.

Amino Acid Sequence↗
PubMed1989

Nucleotide sequence and genetic organization of Hungarian grapevine chrome mosaic nepovirus RNA2.

The complete nucleotide sequence of hungarian grapevine chrome mosaic nepovirus (GCMV) RNA2 has been determined. The RNA sequence is 4441 nucleotides in length, excluding the poly(A) tail. A polyprotein of 1324 amino acids with a calculated molecular weight of 146 kDa is encoded in a single long open reading frame extending from nucleotides 218 to 4190. This polyprotein is homologous with the protein encoded by the S strain of tomato black ring virus (TBRV) RNA2, the only other nepovirus sequenced so far. Direct sequencing of the viral coat protein and in vitro translation of transcripts derived from cDNA sequences demonstrate that, as for comoviruses, the coat protein is located at the carboxy terminus of the polyprotein. A model for the expression of GCMV RNA2 is presented.

Amino Acid Sequence↗
PubMed1988

Cloning full-length cDNA of grapevine chrome mosaic nepovirus.

Full-length cDNA copies of the genomic RNAs of grapevine chrome mosaic virus were obtained and cloned in Escherichia coli by a one-step procedure. The cloning protocol included size selections by agarose-gel electrophoresis of both the single-stranded and the double-stranded full-length cDNAs. First-strand cDNA synthesis was primed with oligodeoxythymidine while second-strand synthesis was primed with specific synthetic oligodeoxynucleotides, allowing cloning of the 3' poly(A) and of the last 5' nucleotides of the viral RNA template. For the 7.2-kb and 4.4-kb viral RNAs, up to 20% and 80%, respectively, of the clones were found to be full-length. Even for large templates, this procedure allows fast and efficient cloning of full-length cDNAs.

Base Sequence↗
PubMed1988

Immunochemical properties of elongation factors 1 of plant origin.

Elongation factors 1 (EF-1) have been isolated from different plants: wheat, yellow lupine, blue lupine, Chinese cabbage and Norway maple. Antibodies for EF-1 from yellow lupine have been obtained in rabbits; antibodies for wheat EF-1 were elicited in mice. The immunological properties of EF-1 were assayed by the following methods: western blotting, double immunodiffusion and rocket immunoelectrophoresis. Our results suggest that one antigenic site is similar for all plant elongation binding factors tested. This epitope probably overlaps the centre of biological activity of EF-1, as was shown for wheat EF-1. The hypothesis concerning the potential presence of plant EF-1 as a subunit of turnip yellow mosaic virus RNA replicase (similar to prokaryotic EF-Tu in the Q beta RNA replicase system) has also been tested using immunotechniques as well as tests of biological activity, but has not been confirmed.

Cross Reactions↗
PubMed1988

Detection of Chrysanthemum stunt viroid (CSV) using nick translated probes in a dot-blot hybridization assay.

We developed a dot-blot hydridization assay for the detection of Chrysanthemum stunt viroid (CSV) in Chrysanthemum plant samples. The probe, a recombinant plasmid containing a full-length monomeric cDNA copy of CSV, is labelled with (32P) by nick-translation. The influence of the hybridization conditions, of the sample denaturation technique and of the plant sap components on the final sensitivity has been studied. The optimized system, involving a formaldehyde denaturation step, allows the detection of as little as 5 pg of purified viroid. Under these conditions, 100 pg of pure viroid diluted in plant sap, or infected plant extract diluted 1:25 in healthy extract can be detected, showing the potential of this method for indexing of Chrysanthemum for CSV infection.

Chrysanthemum cinerariifolium↗
PubMed1988

Nucleotide sequence of the 3' ends of the double-stranded RNAs of grapevine chrome mosaic nepovirus.

Attempts were made to label the termini of dsRNAs corresponding to the two genomic RNAs of grapevine chrome mosaic nepovirus (GCMV). It was not possible to label the 5' ends of the dsRNAs with [gamma-32P]ATP, which suggests that a genome-linked protein blocks their 5' ends. Both dsRNA species were labelled at their 3' ends with pCp. The 3'-terminal sequences were determined by 'wandering spot' or by partial enzymic cleavage analysis. One strand (presumably positive) ended in a poly(A) 30 to 50 nucleotides long whereas the other (presumably negative) ended in 3'-ACCUUUUAAAAAG (RNA1) or 3'-ACCUUUUAAUAAAG (RNA2). The sequences resemble closely those complementary to the 5' ends of the RNAs of tomato black ring virus (strain S), which is distantly related to GCMV.

Base Sequence↗
PubMed1985

Gene for spiralin, the major membrane protein of the helical mollicute Spiroplasma citri: cloning and expression in Escherichia coli.

A library of cloned Spiroplasma citri genomic sequences was constructed by incorporating HindIII digestion fragments into the plasmid vector pBR328. Immunological screening allowed the identification of a recombinant plasmid containing the gene for spiralin, the major membrane protein of S. citri. The spiralin produced by the Escherichia coli transformant was characterized by immunological detection with monoclonal antibody after Western blotting of two-dimensional (isoelectric focusing and sodium dodecyl sulfate-polyacrylamide) electrophoresis gels and by partial proteolytic mapping. The gene for spiralin occurred within a 6.5-kilobase-pair cloned DNA fragment. Spiralin in E. coli was produced regardless of the orientation of the insert within the pBR328 vector. A spiroplasmal DNA sequence which acted as a promoter in E. coli was cloned along with the structural spiralin gene which is expressed in E. coli from that sequence.

Bacterial Outer Membrane Proteins↗
PubMed1984

Expression of the Spiroplasma citri spiralin gene in Escherichia coli. Use of the recombinant plasmid carrying this gene as a molecular probe.

Expression in Escherichia coli of the cloned Spiroplasma citri spiralin gene results in the expression of a 30.5-kDa protein serologically related to spiralin. A protein with the same properties is also present in minor amounts in S. citri cells, suggesting that spiralin is first produced as a preprotein containing a signal polypeptide, which is removed during further processing. Hybridization experiments have demonstrated that pES1, the recombinant plasmid carrying the spiralin gene, can be used as a molecular probe, allowing the detection of S. citri DNA in infected plants and in insect cell cultures.

Bacterial Outer Membrane Proteins↗
PubMed1984

Spiroplasmas and the transfer of genetic material by transformation and transfection.

Two plasmids, pMH1 with 7 kbp and pM41 with 8 kbp were purified from Spiroplasma citri strains MH and M4 respectively. On the basis of guanine + cytosine content and restriction enzyme mapping, the two plasmids are different. The linearized pMH1 plasmid was introduced into Escherichia coli plasmid vector pBR328 and could be cloned in E. coli. Using radioactive probes specific for each plasmid, we found that pM41 was present in three additional S. citri strains and in three other spiroplasmas not belonging to the S. citri species. pMH1 was found as a free 7-kbp plasmid only in the S. citri strain MH. However, the pMH1 probe hybridized strongly with high molecular weight DNA of several S. citri strains and strains of spiroplasmas other than S. citri. The major membrane protein of S. citri, spiralin, is strongly antigenic and rabbit antibodies against whole S. citri cells strongly react with spiralin. Thus, the enzyme-linked immunosorbent assay (ELISA) has been used to screen E. coli clones that were transformed with HindIII-generated S. citri DNA fragments inserted into the HindIII site of pBR328. One E. coli transformant strongly reacted in ELISA with S. citri polyclonal antiserum. The same transformant also gave a positive reaction with monospecific antiserum against spiralin. These results demonstrate that a gene from S. citri, the spiralin gene, could be expressed in a bacterium. The isometric virus SV4, infecting honeybee spiroplasmas of Group I-2, was shown to possess circular single-stranded DNA of molecular weight 1.7 X 10(6) Da. Transfection of spiroplasma G1 with purified DNA of SV4 was achieved. These experiments open the way to the introduction of foreign genes into spiroplasmas.

Bacterial Outer Membrane Proteins↗
PubMedDate not supplied

Multiple alignment and hierarchical clustering of conserved amino acid sequences in the replication-associated proteins of plant RNA viruses.

We have used multiple alignment computer programs to align and hierarchically cluster the conserved amino acid "signature" sequences found in the replication-associated proteins of all plant RNA viruses sequenced so far. These regions, called "polymerase", "nucleotide-binding" and "N-terminal" are well conserved even between viruses which are only distantly related, and are thus very well suited for this type of analysis. Our results show that the clusterings obtained using these very short amino acid sequences are very robust to computing parameters and are surprisingly well matched with the taxonomic grouping of RNA plant viruses. The possibility of using this system as a new taxonomic criterion is discussed.

Amino Acid Sequence↗
PubMedDate not supplied

32P- and biotin-labelled in vitro transcribed cRNA probes for the detection of potato spindle tuber viroid and chrysanthemum stunt viroid.

Replacing nick-translated DNA probes by in vitro transcribed complementary RNA (cRNA) probes considerably increased the sensitivity of dot-blot detection tests of potato spindle tuber viroid and chrysanthemum stunt viroid. As compared to the limit of detection of 5-10 pg of viroid obtained with 32P-labelled DNA probes, cRNA probes allow the detection of less than 1 pg of pure viroid. When labelled with biotin by incorporation of biotin-labelled ribonucleotides, the cRNA probes have a limit of detection of approximately 5 pg of purified viroid.

Biotin↗
PubMedDate not supplied

Analysis of spiroplasma proteins: contribution to the taxonomy of group IV spiroplasmas and the characterization of spiroplasma protein antigens.

Spiroplasma strains of group IV were compared by two-dimensional protein analyses on polyacrylamide gels. Although considerable diversity was evident, the assemblages studied were less heterogeneous than the known strains of group I. Two electrophoretic techniques were used to identify spiroplasma proteins that had been used to immunize rabbits. These included monoclonal antibodies prepared against Spiroplasma citri. In the first technique, protein antigens were purified by immunoaffinity chromatography, then identified with SDS-PAGE. In the second technique, spiroplasma proteins were first separated by SDS-PAGE, then antigens were identified by antibody binding to blot-transferred proteins. Finally, two-dimensional protein electrophoresis has been used as a source of immunogens to characterize monospecific antibodies against individual S. citri proteins.

Antibodies, Bacterial↗