Allan Tereba

RNA tumor virus specific sequences in nuclear DNA of several avian species

Abstract Nucleic acid sequences complementary to single-stranded DNA prepared from the endogenous chicken (C-type) RNA tumor virus, RAV-O, were detected in nuclear DNA from five different avian species. The RAV-O probe hybridized almost completely to DNA from helper factor positive and negative chicken cells. DNA from quail, duck, pigeon and pheasant cells contained nucleotide sequences complementary to a varying degree (5–50%) to the RAV-O genome. Rous sarcoma virus-related sequences were also detected in all avian species, except pigeon. Thus, it appears likely that most if not all species of fowl contain RNA tumor virus sequences in their DNA.

Chromosomal Localization of Protooncogenes

Publisher Summary This chapter discusses the concept of protooncogenes and describes the studies by which these genes have been located in a variety of species, with a marked emphasis on man. The chapter summarizes the chromosomal location of 22 protooncogenes in chicken, mouse, and human cells in tabulated form. It also lists the diseases associated with the homologous retrovirus oncogene and associations with naturally occurring tumors. The chicken protooncogenes were the first examined, mainly for determining the chromosomal association between endogenous retrovirus loci and protooncogenes. This examination, along with Southern blot analyses of diverse species, has revealed no correlation, and it is assumed that these protooncogenes are important growth and/or regulatory genes that infrequently act as nonspecific targets for exogenous retrovirus genomes. The localization of human protooncogenes has progressed at breakneck speed since the discovery that chicken c -myc was involved in avian leukosis virus-induced bursal lymphomas. The localization of c- myc and c- abl to the breakpoints of very consistent translocations in Burkitts lymphoma and chronic myelogenous leukemia, respectively, support the importance of pursuing the localization of protooncogenes by linking specific genes with the disease state of human malignancies.

Characterization of the transformation-specific sequences of avian erythroblastosis virus in normal vertebrate cells

We have prepared a complementary DNA probe for the transformation-specific sequences of avian erythroblastosis virus (AEV) (cDNAAEV). This probe was used to characterize the cellular homologs of these sequences. We confirmed previous observations which had shown a wide-spread occurrence of nucleic acid sequences related to cDNAAEV in vertebrates (Roussel et al., Nature (London) 281, 452, 1979). In cells of invertebrates, sequences related to cDNAAEV could not be detected. Thermal denaturation of hybrids between cDNAAEV and chicken DNA revealed about 6% mismatching which is similar to that found with src and its homolog in chicken cells. In nonavian vertebrates cells cDNAAEV-related sequences showed an additional degree of mismatching of 3–4%. This evolutionary divergence of the AEV transformation-specific information is considerably less than that found for src and its cellular counterparts. The cellular sequences homologous to cDNAAEV were found to be located in chicken chromosomes 10–12 by in situ hybridization. Cellular sarc sequences are found in the same chromosome group. It was also shown that the cellular homolog of cDNAAEV in normal chicken cells is transcribed into RNA.

Cell oncogenes are located on the large microchromosomes in chicken cells

Abstract The chromosomal locations of c-myc and c-myb, the cell homologs of the transforming genes present in myelocytomatosis virus 29, MC29, and avian myeloblastosis virus, AMV, respectively, were determined in White Leghorn chickens using in situ hybridization. Nucleic acid probes containing MC29 and AMV-RNAs were used to localize both c-myc and c-myb to a subset of large microchromosomes. The chromosomal location of c-myc was confirmed using nucleic acid probes containing RNA from MH-2, which also contains a myc-like sequence, and cloned DNA containing the chicken c-myc gene. In conjunction with our previous results localizing c-src and c-erb, we have demonstrated that several cell oncogene homologs appear to be localized on a subset of large microchromosomes.

Asymmetric chromosomal distribution of endogenous retrovirus loci in chickens and mice

Retrovirus-like sequences have been found in the genomes of a large number of species (Coffin 1982). These sequences are inherited in a Mendelian fashion, appear to be stable loci, and can be considered an integral part of an individual’s genetic makeup. However, analysis of related species (Frisby etal. 1979) and some related sublines (Rowe and Kozak 1980) has revealed that these sequences are probably due to rare integration events following infections of gamete or embryonic tissue. The genetic loci resulting from this unique occurrence in animal virology provide an excellent opportunity to observe the interactions of exogenously introduced DNA with a vertebrate genome in a multitude of cell types and at different stages of differentiation

Agarose gel electrophoresis in isozyme separation and visualization

Isozyme analysis of rodent-human somatic cell hybrids has been used frequently to detect specific human chromosomes. The majority of these isozyme systems employs starch gels, the use of which can be laborious when screening large numbers of cell lines. We describe the development of two procedures to detect the long arms of human chromosomes 1 and 2 in Chinese hamster-human cell hybrids by a rapid and reproducible method using 1-mm-thick agarose gels. Detection of human chromosome 1q was accomplished by screening for human fumarate hydratase activity, whose gene has been mapped to 1q42.1. Detection of chromosome 2q was performed by screening for the isozyme isocitrate dehydrogenase 1, which has been localized to 2q32-qter. These systems provide a basis for the further development of procedures for detecting chromosome-specific isozyme markers in agarose gels.

Chemical activation and regulation of a C-type virus from ring-necked pheasant cells

Abstract 20-Methylcholanthrene was used to induce efficiently the permanent expression of non-defective C-type virus in ring-necked pheasant fibroblasts. This chemical induction demonstrated that non-virus-producing ring-necked pheasant cells are unable to produce virus because of a regulatory mechanism and not because they lack a complete virus genome. The induced virus infected and grew to moderate titers in untreated ring-necked pheasant fibroblasts, demonstrating that the virus had permanently overcome the growth restriction mechanism. The virus also grew efficiently in several lines of chicken fibroblasts which restrict A, B, D, and E subgroup oncoviruses. However, it did not grow efficiently, if at all, in fibroblasts from a variety of other avian species which lack an endogenous RAV-O-like virus. The restricted growth in these heterologous avian species is not due to a membrane host range restriction because pseudotypes of a Rous sarcoma virus with a deleted glycoprotein gene and the induced ring-necked pheasant virus can infect the fibroblasts of all avian species tested equally well. This selectivity thus suggests that there may exist a species-specific intracellular restriction mechanism against infecting endogenous virions derived from evolutionarily divergent hosts.