Transcriptome sequencing and characterization of ungerminated and germinated spores of <italic>Nosema bombycis</italic>

Abstract

Nosema bombycis is an obligate intracellular parasitic fungus that utilizes a distinctive mechanism to infect Bombyx mori. Germination, an indispensible process through which microsporidia infect the host cells, is regarded as a key developmental turning point for microsporidia from dormant state to reproduction state. Thus, elucidating the transcriptome changes before and after germination is crucial for parasite control. However, the molecular basis of germination of microsporidia remains unknown. To investigate this germination process, the transcriptome of N. bombycis ungerminated spores and germinated spores were sequenced and analyzed. More than 60 million high-quality transcript reads were generated from these two groups using RNA-Seq technology. After assembly, 2756 and 2690 unigenes were identified, respectively, and subsequently annotated based on known proteins. After analysis of differentially expressed genes, 66 genes were identified to be differentially expressed (P ≤ 0.05) between these two groups. A protein phosphatase-associated gene was first identified to be significantly up-regulated as determined by RNA-Seq and immunoblot analysis, indicating that dephosphorylation might potentially contribute to microsporidia germination. The DEGs that encode proteins involved in glycometabolism, spore wall proteins and ricin B lectin of N. bombycis were also analyzed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed genes responsible for some specific biological functions and processes. The datasets generated in this study provide a basic characterization of the transcriptome changes in N. bombycis during germination. The analysis of transcriptome data and identification of certain functional genes which are robust candidate genes related to germination will help to provide a deep understanding of spore germination and invasion.

First identification of long non-coding RNAs in fungal parasite Nosema ceranae

“…Corradi et al 2008. Liu et al (2016) performed sequencing and analysis of ungerminated and germinated spores of Nosema bombycis using RNA-seq, respectively assembled 2756 and 2690 unigenes based on more than 60 million transcript reads. In our study, over 218.47 million raw reads were generated from three cDNA libraries of N .…”

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

“…Germination of microsporidia is the means of releasing sporoplasms, which involves a series of biologically complex changes (24). To elucidate the molecular basis of the germination process, transcriptome sequencing and quantitative proteomic analysis of ungerminated and germinated spores of N. bombycis have been investigated (25,26). Several genes associated with germination were identified, especially genes involved in protein dephosphorylation (25), and a number of important changes in metabolic pathways were detected during the germination process, such as glycolysis, the pentose phosphate pathway, and purine and pyrimidine metabolism (26).…”

Interaction between SWP9 and Polar Tube Proteins of the Microsporidian Nosema bombycis and Function of SWP9 as a Scaffolding Protein Contribute to Polar Tube Tethering to the Spore Wall

“…Microsporidia infect host cells by a singularly unique invasion mechanism (34). Mature spores are activated under conditions of appropriate environmental stimulation, such as changes in pH and ion concentrations (35). This process finally leads to the explosive discharge of the hollow polar tube, followed by the transfer of the infectious sporoplasm into the host cell, a process known as germination.…”