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Describes a method to obtain high-resolution chromosome preparations in the chicken, Gallus domesticus. Use of synchronization of embryo fibroblast cells; Characteristics of cultures of chicken embryo fibroblasts; RBG- and GTG-banding patterns.

Hydroxyindole-O-methyltransferase (HIOMT) catalyzes the final step of melatonin synthesis, a neurohormone involved in photoperiodism and produced specifically in the pineal gland and in the retina. In the chicken, HIOMT gene transcription appears to be controlled by a circadian oscillator located in the pineal gland. We have characterized the chicken HIOMT gene over 17 kb, including 2.9 kb of 5'-flanking sequence. The major transcript (1.6 kb) is composed of eight exons distributed over 7.5 kb of genomic DNA. A ninth alternative exon was identified 6 kb downstream of exon 8. It was found in minor transcripts in the pineal gland and in the retina. Sequence similarity between exons 8 and 9 suggests their origin by exon duplication. Due to early stop codons, inclusion of exon 9 truncates the open reading frame by up to 33%. A restriction fragment length polymorphism was detected for a BglII site in intron 8. Fluorescence hybridization localized the HIOMT gene on chicken chromosome 1q22. The 5'-flanking region contains GATTAA and TAATCC sequences that may be related to tissue-specific expression. An ATTTAAAT sequence at position -29 would play the role of a TATA box, as evidenced by electrophoretic mobility shift assay. Information obtained in this study open the way to further studies aimed at analyzing the circadian rhythm of transcription at promoter level.

The ets-family of transcription factors is involved in the development of endothelial and hematopoietic cells. Among these genes, fliwas shown to be responsible for erythroblastomas and Ewing's sarcomas. Its involvement in Ewing's sarcoma, a putative neurectodermal tumor, as well as the in situ hybridization studies performed in mice and Xenopus suggested a role in neural crest development. We cloned quail fli cDNA in order to analyze in more detail its expression in neural crest cells, which have been extensively studied in avian species. Fli gene maps on chicken chromosome 1 to band q31->q33. Two RNAs are transcribed, most likely arising from two different promoters. The analysis of its expression in neural crest cells reveals that it is expressed rather late, when the neural crest cells reach their target. Among the various lineages derived from the crest, it is restricted to the mesenchymal one. It is maintained at later stages in the cartilage of neural crest but also of mesodermal origin. In addition, fli is expressed in several mesoderm-derived cells: endothelial cells as well as intermediate and splanchnopleural mesoderm.