Morphology and Transcriptome Analysis of Nosema bombycis Sporoplasm and Insights into the Initial Infection of Microsporidia

Abstract

Once awoken from dormancy, the cellular matter of microsporidia is delivered directly into the host cell cytoplasm through the polar tube. This means that the microsporidia are difficult to study biologically in their active state without a contaminating signal from the host cell. Sporoplasm is a cell type of microsporidia in vitro , but relatively little attention has been paid to the sporoplasm in the past 150 years due to a lack of an effective separation method. Nosema bombycis , the first reported microsporidium, is a type of obligate intracellular parasite that infects silkworms and can be induced to germinate in alkaline solution in vitro . We successfully separated the N. bombycis sporoplasm in vitro , and the morphological and structural characteristics were investigated. These results provide important insight into the biology and pathogenesis of microsporidia and potentially provide a possible strategy for genetic manipulation of microsporidia targeting the sporoplasm.