Kuspa A, Kroos L, Kaiser D
Dev Biol. 1986 Sep;117(1):267-76. doi: 10.1016/0012-1606(86)90369-6.
Certain developmental mutants of Myxococcus xanthus can be complemented (extracellularly) by wild-type cells. Insertions of Tn5 lac (a transposon which couples beta-galactosidase expression to exogenous promoters) into developmentally regulated genes were used to investigate extracellular complementation of the A group mutations. A- mutations reduced developmental beta-galactosidase expression from 18 of 21 Tn5 lac insertions tested and that expression was restored to A- Tn5 lac cells by adding wild-type cells. The earliest A-dependent Tn5 lac normally expresses beta-galactosidase at 1.5 hr of development indicating a developmental block at 1-2 hr in A- mutants. A substance which can rescue the expression of this early Tn5 lac is released by wild-type (A+) but not by A- cells. This substance appears in a cell-free wash of wild-type cells or in starvation buffer conditioned by wild-type cells 1-2 hr after development is initiated. The conditioned starvation buffer also restores normal morphological development to an A- mutant.
黄色黏球菌的某些发育突变体可以被野生型细胞（在细胞外）互补。将Tn5 lac（一种将β-半乳糖苷酶表达与外源启动子偶联的转座子）插入发育调控基因中，用于研究A组突变的细胞外互补。A-突变降低了所测试的21个Tn5 lac插入片段中18个的发育β-半乳糖苷酶表达，通过添加野生型细胞，该表达恢复到A- Tn5 lac细胞。最早的A依赖性Tn5 lac通常在发育1.5小时时表达β-半乳糖苷酶，表明A-突变体在1-2小时时有发育阻滞。一种可以挽救这种早期Tn5 lac表达的物质由野生型（A+）细胞释放，而A-细胞则不能释放。这种物质出现在野生型细胞的无细胞洗涤液中，或在发育开始1-2小时后由野生型细胞调节的饥饿缓冲液中。经调节的饥饿缓冲液也能使A-突变体恢复正常的形态发育。
