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Chicken cell DNA contains sequences which are homologous to the avian erythroblastosis virus oncogene v‐erb. These cellular sequences (c‐erb) have been isolated from a library of chicken cell DNA fragments generated by partial digestion with AluI and HaeIII and shown to be shared by at least two loci in the chicken DNA. One of them, denoted c‐erbB, contains approximately 1.8 kilobase pairs of chicken DNA homologous to the 3′ part of the v‐erb oncogene (v‐erbB). Restriction mapping studies show that the c‐erbB DNA sequences homologous to v‐erbB are distributed among six EcoRI fragments located in a single genomic region. Heteroduplexes between v‐erbB in viral RNA and cloned c‐erbB DNA show that the chicken DNA sequences homologous to v‐erbB are interrupted by 11 DNA sequences not present in the v‐erb oncogene. We conclude from our data that the c‐erbB locus might represent the cellular progenitor for the v‐erbB domain of the v‐erb oncogene.

Using an antiserum to a bacterially expressed polypeptide corresponding to 56 amino acids of v‐ets, we previously identified in chicken tissues a protein of 54 kd (p54c‐ets) which shares extensive sequence homology to the v‐ets‐encoded domain of the E26‐transforming protein p135gag‐myb‐ets and is thus apparently encoded by the c‐ets proto‐oncogene. We report here that the anti‐ets serum specifically identifies in chicken cells a second set of proteins of 60 kd (p60), 62 kd (p62) and 64 kd (p64) which appear to be highly related to each other but display only a limited domain of homology with p54c‐ets and p135gag‐myb‐ets and are thus probably encoded by a gene(s) partially related to, but different from c‐ets. In contrast to p54c‐ets which is expressed at high levels in chicken lymphoid tissues, prominent syntheses of p62 and p64 were found in both normal and transformed chicken macrophages but not in avian cells corresponding to immature stages of the myeloid differentiation pathway. These observations together with the fact that differentiation of avian myeloblastosis virus‐transformed myeloblasts into macrophage‐like cells after treatment with 12‐O‐tetradecanoylphorbol‐13‐acetate is accompanied by the synthesis of p62 and p64 suggest a role for these proteins in chicken macrophage differentiation or function. Induction of differentiation of human leukemia cell lines HL60 and U937 into macrophages is also accompanied by the increased synthesis of c‐ets‐encoded 68 kd, 62 kd and 58 kd proteins.

Chicken and human cell DNA contains sequences homologous to the avian myeloblastosis virus oncogene, v‐myb. These cellular sequences, c‐myb (human) and c‐myb (chicken), were isolated from libraries of human or chicken cell DNA fragments, generated by partial digestion with the restriction enzymes AluI and HaeIII, and compared. The chicken c‐myb locus isolated from two distinct overlapping recombinant phages, contained five contiguous EcoRI fragments of 5.4, 1.1, 2.1, 2.2 and 9 kbp, accounting for all the bands seen with a v‐myb probe in a complete EcoRI digest of chicken cellular DNA. Likewise, the screening of the human library yielded a recombinant phage hybridizing with the v‐myb specific probe, that contained five EcoRI fragments of 2.8, 2.6, 2.0, 1.2 and 5.0 kbp (the last ending with an artificial EcoRI site, due to the construction of the library) belonging to the c‐myb (human) locus. Probes using the EcoRI chicken DNA cloned fragments revealed corresponding contiguous EcoRI fragments in the human clone. Subsequent analyses of cellular polyadenylated mRNA extracted from human and chicken cells allowed the identification of single RNA species of 3.8 and 4.0 kb, respectively, as the representative transcripts of the c‐myb locus in the two species. Thus, c‐myb appears as a single locus in man and chicken, conserved with a similar structure in the two distantly related species. Our preparation of a specific human c‐myb probe with an increased sensitivity on DNA/RNA blots should facilitate analyses concerning this gene in human normal or tumour cells or tissues.

We have investigated the structure of chicken genomic DNA homologous to v-ets, the second cell-derived oncogene of avian retrovirus E26. We isolated a c-ets locus spanning ca. 30.0 kilobase pairs (kbp) in the chicken genome with homologies to 1,202 nucleotides (nt) of v-ets (total length, 1,508 nt) distributed in six clusters along 18.0 kbp of the cloned DNA. The 5'-distal part of v-ets (224 nt) was homologous to chicken cellular sequences contained upstream within a single 16.0-kbp EcoRI fragment as two typical exons but not found transcribed into the major 7.5-kb c-ets (or 4.0-kb c-myb) RNA species. Between these two v-ets-related cellular sequences we found ca 40.0 kbp of v-ets-unrelated DNA. Finally, the most 3' region of homology to v-ets in the cloned DNA was shown to consist of a truncated exon lacking the nucleotides coding for the 16 carboxy-terminal amino acids of the viral protein but colinear to one of the two human c-ets loci, c-ets-2.

Over the past few years a variety of genes have been described whose protein products share similarity with that of the c-ets-1proto-oncogene, the cellular counterpart of the v-etsoncogene of the avian E26 retrovirus. This so-called "etsfamily" of transcription factors includes at least a dozen members present in several organisms. We have questioned the common evolutionary origin of these various gene products. By constructing phylogenetical trees with different methods, we show that the etsfamily is very ancient since the duplication of the various groups of etsrelated proteins occurred before the Arthropods/Vertebrates split (ca. 500 million years).

Two overlapping c-ets-1 cDNA clones were isolated which contained the alpha and beta genomic sequences homologous to the 5' end of v-ets not detected in the previously described c-ets RNA species or proteins. Nucleotide sequencing demonstrated that these cDNAs corresponded to the splicing of alpha and beta to a common set of 3' exons (a through F) already found in the p54c-ets-1 mRNA. They contained an open reading frame of 1,455 nucleotides which could encode a polypeptide of 485 amino acids with a predicted molecular mass of 53 kilodaltons. However, when expressed in COS-1 cells, the cDNAs directed the synthesis of a protein with an apparent molecular mass in sodium dodecyl sulfate-polyacrylamide gel electrophoresis of 68 kilodaltons, p68c-ets-1, comigrating with a protein expressed at low levels in normal chicken spleen cells. These two proteins were shown to be identical by partial digestion with protease V8. Northern (RNA) blot hybridization analysis with the p68c-ets-1 -specific sequence and RNase protection experiments showed that the corresponding mRNA was expressed in normal chicken spleen and not in normal chicken thymus or in various T lymphoid cell lines. Thus, two closely related proteins, having distinct amino-terminal parts, are generated within the same locus by alternative addition of different 5' exons, alpha and beta or I54, respectively, onto a common set of 3' exons (a to F). Finally, we demonstrate that an aberrant splicing event between a cryptic splice donor site in c-myb exon E6 and the normal splice acceptor site of c-ets-1 exon alpha involved in the genesis of the E26 myb-ets sequence.

AbstractChrysops univittatusMacquart females were more abundant in late July and early August in southwestern Quebec. Dry-ice baited canopy trap collections consisted of 55% (n= 177) of the nulliparous and 77% (n= 91) of the parous females. Incidence of nectar feeding, as determined by cold anthrone test, was 73% (n= 244) and 96% (n= 268) of the females contained sperm; no difference was found between parous and nulliparous females. This species is anautogenous, and only one gonotrophic cycle was recorded following ovary dissection. Number of ovarioles was correlated with body size (as determined by wing length) by linear regression analysis.