Fritz A F, Cho K W, Wright C V, Jegalian B G, De Robertis E M
Department of Biological Chemistry, University of California, Los Angeles 90024-1737.
Dev Biol. 1989 Feb;131(2):584-8. doi: 10.1016/s0012-1606(89)80029-6.
Multiple kinds of clones and restriction fragment polymorphisms are frequently encountered when analyzing genes of the tetraploid frog Xenopus laevis. Two types of cDNA clone have been isolated for homeobox gene 2. Analysis of their corresponding genomic clones confirmed the existence of clearly distinct restriction maps; in addition the nearby presence of two additional homeoboxes suggests that this region is homologous to the Hox 2 gene complex of mammals. We asked whether the genetic polymorphism in Xenopus results from increased allelic differences due to tetraploidy or from having duplicated Hox 2 complexes. Using X. laevis/Xenopus borealis interspecies hybrids we show that the two types of X. laevis homeobox gene 2 transcripts result from two different genetic loci. They cannot represent alleles of the same gene because they do not segregate independently in the F1 hybrid progeny. Most other X. laevis homeobox genes studied so far are also found in two versions. Thus X. laevis seems to have two homeobox genes, both of which are expressed, for each one present in mammals or other vertebrates.
在分析四倍体青蛙非洲爪蟾的基因时，经常会遇到多种克隆和限制性片段多态性。已分离出两种类型的同源异型框基因2的cDNA克隆。对其相应基因组克隆的分析证实存在明显不同的限制性图谱；此外，附近还有另外两个同源异型框，这表明该区域与哺乳动物的Hox 2基因复合体同源。我们探究了非洲爪蟾的遗传多态性是由于四倍体导致等位基因差异增加，还是由于Hox 2复合体重复。利用非洲爪蟾/北方爪蟾种间杂种，我们发现非洲爪蟾同源异型框基因2的两种转录本来自两个不同的基因位点。它们不可能代表同一基因的等位基因，因为它们在F1杂种后代中不独立分离。到目前为止研究的大多数其他非洲爪蟾同源异型框基因也有两个版本。因此，对于哺乳动物或其他脊椎动物中存在的每一个同源异型框基因，非洲爪蟾似乎都有两个都表达的同源异型框基因。
