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Biomedical subjects

J Merregaert

Publications and source records attributed to J Merregaert.

At least 55 records · Page 3Linked to original sources
PubMed1986

Oncogene involvement in radiation- and virus-induced mouse osteosarcomas.

Internal irradiation of mice using bone seeking radionuclides results in the activation of endogenous retroviruses and in the subsequent development of bone tumors. Genomic DNA from an osteosarcoma cell line, derived from an 90Sr-induced bone tumor, was cotransfected with the plasmid pSV2-neo into NIH/3T3 cells and G418-resistant transfectants gave rise to colonies in soft agar. Southern blot analysis of these first cycle transformants revealed the presence of extra copies of c-ras. We have analysed the arrangement of ecotropic murine leukemia proviral sequences in seven 90Sr-induced bone tumors and one osteosarcoma cell line of CF1-mice. Integration of ecotropic and/or ecotropic recombinant proviruses seems to be involved in rearrangements of 3' provirus cellular junction fragments occurring in all tumor DNAs analysed, but no indication for site-specific integration was found. We also determined the primary structure of FBR-MuSV, a transforming retrovirus able to induce bone tumors in newborn mice. FBR-MuSV contains sequences from all four exons of the murine c-fos gene, but lacks sequences encoding the first 24 and the last 98 amino acids of the c-fos gene product. The coding region of FBR-MuSV has also undergone two small in frame deletions. Thus, the v-fosFBR-MuSV retains 236 amino acids of the 380 amino acids of the murine c-fos product. In FBR-MuSV-transformed cells two fos-containing mRNAs have been detected: a 3.3-kb full-size genomic RNA and a 2.2-kb subgenomic mRNA as revealed by both fos- and MuLV-hybridization probes.

Animals↗
PubMed1986

Genome organisation of the FBR-osteosarcoma virus complex: identification of a subgenomic fos-specific message.

The FBR murine virus complex together with the FBJ murine virus complex are known to be bone tumor inducers in newborn mice. Both transforming viruses have transduced c-proto-fos-derived sequences in their genome. FBR-MuSV was molecularly cloned as a biologically active 10-kbp EcoRI fragment from non-productively transformed rat embryo fibroblasts into Charon phage 4A (lambda MOL503) and subsequently subcloned in plasmid pBR322 (pMOL503). Its natural associated helper FBR-MuLV, excized as an internal 8.2-kbp PstI proviral DNA fragment from chronically infected NIH/3T3 cells, was cloned into the unique PstI site of pBR322. Comparative analysis of the restriction maps of FBR-MuSV and FBR-MuLV together with the electron microscopic analysis of heteroduplex DNA molecules formed between both molecular clones suggested that FBR-MuLV is the parental virus of FBR-MuSV. fos- and fox-specific DNA hybridisation probes identified a genomic sized 3.3-kb mRNA and a subgenomic 2.2-kb messenger RNA. Using a 5'-gag hybridisation probe, only the genomic 3.3-kb RNA molecule was detected, demonstrating that a donor splice site is present upstream of the gag sequences and used to generate the fos-specific 2.2-kb subgenomic mRNA.

Animals↗
PubMed1985

Nucleotide sequence of the envelope gene of radiation leukemia virus.

The nucleotide sequence and the predicted amino acid sequence of the envelope gene (env) of RadLV/VL3 (T+L+) has been determined. RadLV/VL3 (T+L+) is a highly thymotropic (T+) and leukemogenic (L+) murine recombinant retrovirus continuously produced at high titer by BL/VL3 cells, a line established in culture from a radiation leukemia virus (RadLV)-induced C57BL/Ka mouse thymic lymphoma. The envelope gene is strikingly similar (92% homologous) to that encoded by the ecotropic Akv-MuLV. Among the differences, 134 scattered, although unevenly distributed point mutations (6.4%), two 9-bp deletions as well as a 6-bp insertion were observed (which result in 49 amino acid changes in the env gene of RadLV/VL3 (T+L+)).

Abelson murine leukemia virus↗
PubMed1985

Proviral genome of radiation leukemia virus: molecular cloning of biologically active proviral DNA and nucleotide sequence of its long terminal repeat.

The proviral genome of a leukemogenic and thymotropic C57BL/Ka mouse retrovirus, RadLV/VL3(T+L+), was cloned as a biologically active PstI insert in the bacterial plasmid pBR322. Its restriction map was compared with those, already known, of two nonthymotropic and nonleukemogenic viruses of the same mouse strain: the ecotropic BL/Ka(B) virus and the xenotropic constituent of the radiation leukemia virus complex. Differences were observed around the gag-pol gene junction, in the pol gene, and in the env gene. Moreover, the nucleotide sequence of the RadLV/VL3(T+L+) long terminal repeat revealed the existence of two copies of a 43-base-pair sequence, of which BL/Ka(B) possesses only one copy.

Animals↗
PubMed1984

Characterization of the FBR-murine osteosarcoma virus complex: FBR-MuSV encodes a FOS-derived oncogene.

The FBR murine osteosarcoma virus complex, isolated from a radiation-induced osteosarcoma of an X/Gf mouse causes the rapid appearance of osteosarcomas in newborn mice and transforms fibroblasts in vitro. The two components of the FBR-viral complex have been isolated separately in tissue culture: FBR-MuLV by end-point dilution and FBR-MuSV by the establishment of mouse [FBR-NP 117 (NIH 3T3)] and rat non-producer cell lines [FBR-NP415 (REF)]. The host range and RNase Tl fingerprint analysis of FBR-MuLV demonstrated a pattern closely related to, but distinguishable from, Akv-MuLV. Transformed cells from both mice and rats contain a rescuable FBR-MuSV genome. These pseudotypes produce foci in tissue culture and induce osteosarcomas in susceptible mouse strains. An FBR-MuSV (FBR-MuLV) cDNA probe detects a 5.2 kb HindIII and a 9.5 kb EcoRI FBR-MuSV-specific fragment in FBR-MuSV-transformed non-producer rat cells. The same fragments hybridized with a fos specific probe, demonstrating that FBR-provirus contains a c-fos-derived onc-gene.

Animals↗
PubMed1984

[Isolation and characterization of retroviruses expressed in murine osteosarcomas induced by 90Sr].

The induction of osteosarcomas with 90Sr in CF1 mice is associated with the expression of ecotropic type-C RNA viruses devoid of sarcomatogenic activity. In contrast, the FBR murine osteosarcoma virus complex, isolated from a 90 Sr-induced osteosarcoma of a X/Gf mouse [M. Finkel et al. (1)], causes the rapid appearance of osteosarcomas in newborn mice and transforms fibroblasts in vitro. The transforming capacity of FBR murine sarcoma virus has been associated as an oncogene homologous to v-fos.

Animals↗
PubMed1981

Recombinants between temperature-sensitive mutants of rauscher murine leukemia virus and BALB:virus-2: genetic mapping of the Rauscher murine leukemia virus genome.

Recombinant viruses were generated in tissue culture between Rauscher murine leukemia virus (MuLV) temperature-sensitive (ts) mutants restricted at different steps in virus replication and a mouse endogenous xenotropic virus, BALB:virus-2. Mutants used included ts 28, a late mutant which releases noninfectious viruses at 39 degrees C, and ts 29, a double mutant with a ts lesion in its reverse transcriptase and a late block affecting virus budding. Immunological typing of the translational products of clonal recombinant viruses made it possible to establish their partial genetic maps and localize regions of the viral genome affected by different ts lesions. Recombinants involving Rauscher MuLV ts 28 invariably contained BALB-virus-2 p15, p12, and p30 proteins, localizing the late defect in replication by this mutant to the 5' moiety of the viral gag gene. All ts 29-derived recombinants contained the entire BALB:virus-2 gag and pol genes. Substitution of the pol gene is in agreement with the reported thermolability of Rauscher MuLV ts 29 reverse transcriptase (Tronick et al., J. Virol. 16:1476-1482, 1975). Substitution of the gag gene suggests that internal structural proteins are actively involved in the virus budding processing. Rauscher MuLV recombinants were used to establish the genetic map of the Rauscher MuLV genome by T1 oligonucleotide fingerprinting analysis. Detection of Rauscher MuLV T1 oligonucleotides in representative recombinant viruses, whose protein phenotypes were established by immunological techniques, permitted their assignment to specific regions of the viral genome. The genetic map of Rauscher MuLV generated in these studies should be useful for identifying and characterizing the viral gene(s) involved in leukemogenesis.

Animals↗
PubMed1978

Sequence of 129 nucleotides at the 3'-terminus of encephalomyocarditis virus RNA.

The sequence of 129 nucleotides next to the poly(A) tail of encephalomyocarditis virus RNA has been determined by rapid gel sequencing of cDNA synthesized with DNA polymerase I or reverse transcriptase and a phasing primer, [5'-32P]p(dT)8dC. The sequence is in accord with (a) the pyrimidine tracts which were mapped in blocks along the cDNA, (B) the sequences of seven characteristic T1 RNase oligonucleotides in the RNA transcribed from the cDNA with RNA polymerase, and (c) a limited amount of sequence deduced by partial spleen phosphodiesterase digestion and depurination of endonuclease IV oligonucleotides. The 3' end shows little secondary structure on its own. Ten nonsense codons block all three reading frames such that at least 26 nucleotides do not code for protein. The possible function of a homology A-A-U-A-A-A with other polyadenylated RNAs is discussed.

Base Sequence↗
PubMed1978

The 3'-Terminal nucleotide sequence of encephalomyocarditis virus RNA.

Poly(A)-containing encephalomyocarditis virus RNA functions as an excellent template for cDNA synthesis in vitro with an RNA-dependent DNA polymerase in the presence of an oligothymidylate primer. Under appropriate conditions, discrete transcripts of increasing chain length were obtained, suitable for sequence analysis. A limited cDNA fragment of 36 nucleotides, primer (dT)10 included, was synthesized when dGTP was omitted from the reaction mixture and its primary structure was elucidated using direct DNA-sequencing methods. The complement corresponds to the 3' end of encephalomyocarditis RNA. The hexanucleotide (5'-3')(A-A-U-A-A-A) found in this sequence is also present in all 3' non-coding regions of poly(A)-containing eukaryotic mRNAs studied until now, in nearly identical positions relative to the poly(A) tail. The possible biological significance of this structural homology is discussed.

Base Sequence↗
PubMed1976

Complete nucleotide sequence of bacteriophage MS2 RNA: primary and secondary structure of the replicase gene.

Bacteriophage MS2 RNA is 3,569 nucleotides long. The nucleotide sequence has been established for the third and last gene, which codes for the replicase protein. A secondary structure model has also been proposed. Biological properties, such as ribosome binding and codon interactions can now be discussed on a molecular basis. As the sequences for the other regions of this RNA have been published already, the complete, primary chemical structure of a viral genome has now been established.

Base Sequence↗