Escalante Ricardo, Yamada Yohko, Cotter David, Sastre Leandro, Sameshima Masazumi
Instituto de Investigaciones Biomédicas CSIC/UAM, Gene Expression, Arturo Duperier, 4, 28029-Madrid, Spain.
Mech Dev. 2004 Jan;121(1):51-6. doi: 10.1016/j.mod.2003.11.001.
The MADS-box transcription factor SrfA is involved in spore differentiation in Dictyostelium [Development 125 (1998) 3801]. Mutant spores show an altered morphology and loss of viability. A detailed structural analysis of mutant spores has been performed to gain insight into the specific aspects of spore differentiation in which SrfA is involved. Two main structural defects have been observed. One is the formation of high order actin structures, the so-called actin rods. SrfA mutant spores showed the initial stages of rod formation but no mature rods were found in older spores either in the nucleus or the cytoplasm. Moreover, phosphorylation of actin, that is believed to stabilize the actin rods, is strongly reduced in the mutant. The other defect observed was the formation of the spore coat. Young srfA- spores show basically normal trilaminar coat structures suggesting that release of prespore vesicles and basic assembly of the coat takes place in the absence of SrfA. However, the outer layer gets wavier as the spore ages and suffers a progressive degradation suggesting a late defect in the stability of the spore coat. Taken together, these results suggest that SrfA is involved in late events of spore maturation necessary for spore stability.
MADS盒转录因子SrfA参与盘基网柄菌的孢子分化过程[《发育》125卷（1998年）第3801页]。突变孢子表现出形态改变和活力丧失。已对突变孢子进行了详细的结构分析，以深入了解SrfA所涉及的孢子分化的具体方面。观察到两个主要的结构缺陷。一个是高阶肌动蛋白结构的形成，即所谓的肌动蛋白杆。SrfA突变孢子显示出杆形成的初始阶段，但在较老的孢子中，无论是细胞核还是细胞质中都未发现成熟的杆。此外，据信能稳定肌动蛋白杆的肌动蛋白磷酸化在突变体中显著降低。观察到的另一个缺陷是孢子壁的形成。年轻的srfA - 孢子显示出基本正常的三层壁结构，这表明在没有SrfA的情况下，前孢子囊泡的释放和壁的基本组装会发生。然而，随着孢子老化，外层变得更皱，并逐渐降解，这表明孢子壁稳定性存在后期缺陷。综上所述，这些结果表明SrfA参与了孢子稳定性所需的孢子成熟后期事件。
