title: The multiple beta-tubulin genes of Xenopus: isolation and developmental expression of a germ-cell isotype beta-tubulin gene.
abstract: In this report, we demonstrate the presence of multiple beta-tubulin genes in Xenopus and begin to explore the regulation of isotypes within the beta-tubulin family by focusing on the characterization of a specific beta-tubulin cDNA derived from a Xenopus oocyte library. This clone (XLOT: Xenopus laevis oocyte beta-tubulin) contains the entire protein coding and 3'-untranslated regions of the gene, and is only missing approximately eleven nucleotides from the start of transcription. The XLOT transcript is ubiquitously expressed, but steady-state amounts are highest in immature oocytes and in testes. Consistent with the present understanding of this type of autoregulation, levels of oocyte beta-tubulin transcript vary in accordance with fluctuating polymeric/monomeric tubulin protein ratios both in the developing oocyte and as the late stage oocyte matures to an unfertilized egg. In addition, steady-state levels of the oocyte beta-tubulin transcript do not increase as the total number of cells per embryo increase during embryogenesis. Although one major and three minor transcriptional start sites are utilized in immature oocytes and adult tissues, usage of each individual site varies during oogenesis and embryogenesis. The preferential expression in germ cells indicate that the oocyte beta-tubulin transcript may provide a useful marker for gonadal differentiation in early amphibian development.
authors.affiliation: Brookdale Center for Molecular Biology, Mount Sinai School of Medicine, New York, NY 10029.
authors.forename: J J
authors.initials: JJ
authors.lastname: Bieker
authors.forename: M
authors.initials: M
authors.lastname: Yazdani-Buicky
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004247:DNA / Q000737:chemistry*; D015342:DNA Probes; D005314:Embryonic and Fetal Development / Q000235:genetics; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009865:Oocytes / Q000737:chemistry*; D009866:Oogenesis / Q000235:genetics; D012313:RNA / Q000737:chemistry*; D014404:Tubulin / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D014982:Xenopus laevis / Q000235:genetics*
chemical_list: D015342:DNA Probes; D014404:Tubulin; D012313:RNA; D004247:DNA