Arthroconidium-Spherule-Endospore Transformation in Coccidioides immitis
Arthroconidium-Spherule-Endospore Transformation in Coccidioides immitis
复制标题
粗球孢子菌中的节分孢子-小球-内生孢子转化
DOI：
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
S. Sun
中科院分区：
文献类型：
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作者：
G. Cole;S. Sun
Coccidioides immitis is a peculiar pathogen that remains a taxonomic enigma. Its natural habitat is soil, geographically limited with rare exceptions to the arid and semiarid regions of the western hemisphere, where it grows as a mold, producing dry arthroconidia. The conidia are dispersed as aerosols when soil is disturbed and serve as infectious propagules for humans and other animals. Infection is associated with morphological transformation of the conidium into a multinucleate spherule, the contents of which subsequently differentiate into a myriad of tiny, uninucleate endospores. The latter are released from the parent spherule, and each endospore is potentially capable of initiating a second generation of spherules within the host. Thus, C. immitis is a diphasic microorganism, characterized by distinct saprobic and parasitic cycles (Figure 1). The saprobic phase of C. immitis differs little from that of other soil fungi that produce arthroconidia (Sigler and Carmichael, 1976; Carmichael et al., 1980) and reveals morphological features that suggest an ascomycetous relationship, e.g., septate hyphae, simple septal pores, and Woronin bodies. On the other hand, it is the only species of arthroconidial fungus known to produce a primary infection in humans and to be capable of undergoing transformation from conidium to spherule to disseminating endospores within the host. Hence, C. immitis is unique among fungi that cause human mycoses, being distinguished from morphogenetically similar saprobes by its pathogenicity and from other pathogenic fungi by its unusual parasitic cycle. Coccidioides remains a monospecific formgenus.
