Life Cycle and the Study of Ribosomal RNA Genes in a Microsporidian Isolate (Nosema sp.) from Eurema blanda arsakia by in vitro Cultivation
Date Issued
2009
Date
2009
Author(s)
Tsai, Yi-Chun
Abstract
A microsporidium was isolated from the larvae of the Three Spot Grass Yellow butterfly, Eurema blanda arsakia, and named as an EB isolate. This microsporidian isolate possesses the molecular and morphological characteristics of the genus Nosema. The organization of the rRNA genes is LSU rRNA-ITS-SSU rRNA-IGS-5S, which matches that of true Nosema species. Phylogenetic analysis, based on the sequences of rRNA genes, placed this isolate as closely related to N. plutellae, N. spodopterae, and N. bombycis. Ultrastructures of each development stage of this isolate, including meront, sporont, sporoblast, and mature spore, also confirmed its Nosema character. The in vitro propagation system of this isolate in IPLB-LD652Y (Lymantria dispar) and NTU-LY (Lymantria xylina) cell lines was successfully established. In life cycle study, the development of this microsporidium under an in vitro cultivation system was observed. It was found to develop in the nucleus of the host cell, a circumstance never encountered in other Nosema-genus microsporidia. An extra-cellular vegetative stage of this microsporidium was also found after 14 days of infection. Besides, during our study of their life cycle, we found that both meront and sporont can internalize the host cell component during their development, why and how they internalize those components is still an interesting and unknown question. Microsporidia are long considered as amitocondrate organism, but in our study, the EB isolate can be clearly stained by the mitochondrion specific dye. The results of immuno-gold study also confirm the existence of mitochondrial cytochrome C oxidase in the microsporidia. Those mitochondria protein might come from the internalized host cell components.
Subjects
Microsporidium
Nosema
intra-nuclear development
mitochondrion
ribosomal RNA
phylogenetic analysis
Type
thesis
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