MENDELIAN AND NON-MENDELIAN MUTATIONS AFFECTING SURFACE-ANTIGEN EXPRESSION IN PARAMECIUM-TETRAURELIA
MENDELIAN AND NON-MENDELIAN MUTATIONS AFFECTING SURFACE-ANTIGEN EXPRESSION IN PARAMECIUM-TETRAURELIA
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DOI：
10.1128/mcb.4.8.1583
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发表时间：
1984-01-01
影响因子：
5.3
通讯作者：
FORNEY, JD
中科院分区：
文献类型：
--
作者：
EPSTEIN, LM;FORNEY, JD
设计了一种筛选程序，用于分离X射线诱导的突变，这些突变影响四脲假单胞菌中A固定抗原（i-抗原）的表达。通过这种方法分离的两个突变被证明是在修饰基因中。这2个基因彼此不连锁，并且与结构A1抗原基因不连锁。这些是草履虫属中鉴定的第一个影响表面抗原表达的修饰基因。发现另一种突变是A1-抗原基因下游序列的缺失。在携带这种突变的细胞中，A i抗原基因紧邻大核染色体的末端。在这些细胞中，A1-抗原的表达不受影响，表明下游序列对于A1-抗原基因的调节和表达并不重要。还回收了稳定的细胞系，其显示A1-抗原基因的大核缺失的非孟德尔遗传。该突变体在其大核中不含该基因，但在其微核中含有该基因的完整拷贝。在野生型动物的细胞质中，微核基因包含在发育中的大核中;在突变体的细胞质中，A i-抗原基因掺入大核中受到抑制。这是第一个证据表明，在纤毛虫中有一种机制可以通过调节基因并入发育中的大核来控制基因的表达。
A screening procedure was devised for the isolation of X-ray-induced mutations affecting the expression of the A immobilization antigen (i-antigen) in P. tetraurelia. Two of the mutations isolated by this procedure proved to be in modifier genes. The 2 genes are unlinked to each other and unlinked to the structural A i-antigen gene. These are the first modifier genes identified in a Paramecium sp. that affect surface antigen expression. Another mutation was found to be a deletion of sequences just downstream from the A i-antigen gene. In cells carrying this mutation, the A i-antigen gene lies in close proximity to the end of a macronuclear chromosome. The expression of the A i-antigen is not affected in these cells, demonstrating that downstream sequences are not important for the regulation and expression of the A i-antigen gene. A stable cell line was also recovered which shows non-Mendelian inheritance of a macronuclear deletion of the A i-antigen gene. This mutant does not contain the gene in its macronucleus, but contains a complete copy of the gene in its micronucleus. In the cytoplasm of wild-type animals, the micronuclear gene is included in the developing macronucleus; in the cytoplasm of the mutant, the incorporation of the A i-antigen gene into the macronucleus is inhibited. This is the first evidence that a mechanism is available in ciliates to control the expression of a gene by regulating its incorporation into developing macronuclei.