Fortwendel Jarrod R, Panepinto John C, Seitz Amy E, Askew David S, Rhodes Judith C
Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH 45267-0529, USA.
Fungal Genet Biol. 2004 Feb;41(2):129-39. doi: 10.1016/j.fgb.2003.10.004.
Expression of rasA plays an important role in conidial germination in Aspergillus nidulans. Conidial germination is required to initiate both infection and asexual development in the opportunistic pathogen Aspergillus fumigatus. Therefore, we sought to determine the requirements for Ras proteins in conidial germination and asexual development of A. fumigatus. A second homolog, rasB, has been identified that characterizes a new subclass of Ras genes. Dominant active (DA) and dominant negative (DN) mutations of each gene were introduced into protoplasts as transgenes. DArasA expression led to reduced conidiation, malformed conidiophores, and altered mitotic progression, whereas expression of DNrasA caused a significant reduction in the rate of conidial germination. In contrast, expression of DNrasB slightly delayed the initiation of germination and caused the development of conidiophores in submerged culture. DArasB expression led to reduced conidiation. RasA and RasB appear to play different, but overlapping, roles in the vegetative growth and asexual development of A. fumigatus.
rasA的表达在构巢曲霉的分生孢子萌发中起重要作用。在机会致病菌烟曲霉中，分生孢子萌发是启动感染和无性发育所必需的。因此，我们试图确定Ras蛋白在烟曲霉分生孢子萌发和无性发育中的需求。已鉴定出第二个同源物rasB，它代表了Ras基因的一个新亚类。将每个基因的显性激活（DA）和显性负性（DN）突变作为转基因导入原生质体。DArasA的表达导致分生孢子形成减少、分生孢子梗畸形以及有丝分裂进程改变，而DNrasA的表达导致分生孢子萌发率显著降低。相比之下，DNrasB的表达略微延迟了萌发起始，并导致在深层培养中分生孢子梗的形成。DArasB的表达导致分生孢子形成减少。RasA和RasB似乎在烟曲霉的营养生长和无性发育中发挥不同但重叠的作用。
