Two Multiallelic Mating Compatibility Loci Separately Regulate Zygote Formation and Zygote Differentiation in the Myxomycete PHYSARUM POLYCEPHALUM.
Two Multiallelic Mating Compatibility Loci Separately Regulate Zygote Formation and Zygote Differentiation in the Myxomycete PHYSARUM POLYCEPHALUM.
复制标题
两个多等位基因交配相容性位点分别调节粘菌多头菌中的合子形成和合子分化。
作者：
P. Youngman;R. Anderson;C. E. Holt
多头绒泡菌变形虫的交配，其最终结果是一个“原质团”，最近被证明是由两个相容性位点，matA（或mt）和matB（Dee 1978; Youngmanet al. 1979）。我们提出的证据表明，matA和matB分别调节两个离散阶段的交配：在第一阶段，阿米巴（通常是单倍体）融合成对，与matB基因型确定的特异性，形成二倍体合子;随后的受精卵分化成疟原虫是由matA调节，不受matB的影响。携带不同的matA和matB等位基因的阿米巴原虫的混合物形成二倍体的程度为10%至15%的细胞存在，和二倍体分化成原质团。当只有matB等位基因不同，二倍体细胞仍然形成了相当的（5至10%）的程度，但而不是分化，这些二倍体仍然是变形虫。当菌株携带相同的matB等位基因时，二倍体细胞的形成大大减少：在类似matB、类似matA的混合物中，检测的320个细胞中没有一个是二倍体;在类似matB、不像matA的混合物中，可以检测到分化的二倍体，但不像matB、不像matA的混合物的频率仅为10（-3）到10（-2）。非分化二倍体变形虫恢复不喜欢matB，喜欢matA的混合物是通过广泛的增长，遗传稳定，即使他们比单倍体（10小时与8小时的加倍期）增长缓慢，并可以与单倍体和二倍体杂交。这种高倍性和混合倍性杂交的结果表明，核配生殖并不总是伴随着合子的形成和分化。
The mating of Physarum polycephalum amoebae, the ultimate consequence of which is a "plasmodium," was recently shown to be governed by two compatibility loci, matA (or mt) and matB (Dee 1978; Youngmanet al. 1979). We present evidence that matA and matB separately regulate two discrete stages of mating: in the first stage, amoebae (which are normally haploid) fuse in pairs, with a specificity determined by matB genotype, to form diploid zygotes; subsequent differentiation of the zygotes into plasmodia is regulated by matA and is unaffected by matB. Mixtures of amoebae carrying unlike matA and matB alleles formed diploids to the extent of 10 to 15% of the cells present, and the diploids differentiated into plasmodia. When only the matB alleles differed, diploid cells still formed to a comparable (5 to 10%) extent, but rather than differentiating, these diploids remained amoebae. When strains carried the same alleles of matB, formation of diploid cells was greatly reduced: in like-matB, like-matA mixtures, none of 320 cells examined was diploid; in like-matB, unlike mat-A mixtures, differentiating diploids could be detected, but at only 10(-3) to 10(-2) the frequency of unlike-matB, unlike-matA mixtures. The nondifferentiating diploid amoebae recovered from unlike-matB, like-matA mixtures were genetically stable through extensive growth, even though they grew more slowly than haploids (10-hr vs. 8-hr doubling period), and could be crossed with both haploids and diploids. The results of such higher ploidy and mixed ploidy crosses indicate that karyogamy does not invariably accompany zygote formation and differentiation.