| Microspora are a large and diverse group of parasitic protozoa without mitochondria. They are known to cause diseases in fish and insects such as silkworms, bees and locusts. Only in the last decade have microsporidian parasites been recognized as important pathogens of humans. Since Enterocytozoon bieneusi was discovered to cause opportunistic infections in AIDS patients (Keeling and McFadden, 1998), the number of microsporidian pathogens described in humans has increased considerably (Keeling and McFadden, 1998). There are five genus of microsporidia pathogenic to the silkworm to be found by now. N. bombycis, which cause the destructive pebrine disease in the commercially important silkworm Born byx mon was first recognized in the last century. Now the pebrine disease is still epidemic in silk production countries. N.bombycis is quarantined in production egg of silkworm because it has germination infection. Because the classification of strange microsporidia can enlarge variety of biology and heighten quality of quarantining to silkworm egg, it very important to classify strange microsporidia. Over the past few years, interest in the molecular biology of microsporidia has increascd.Many aspects of their ribosomal RNA genes have been reported (http://mbcr.bcm.tmc.edu/smallRNAIsma11rna.html). These sequences were used to study the early eukaryotic evolution ((Van de Peer et al,1997;Vossbrinck et al., 1987; Cavalier et aL, 1987, 1991) and for a practical purpose, to assist in species identification (Vossbrinck et al., 1993; Malone, 1996;Yoshinori Hatakeyama et al, 1997) and to understand relationships between species (Baker et al., 1994). In addition, pulsed-field gel electrophoresis was used to investigate molecular karyotyping (Munderloh et al., 1990; Malone and Mcivor, 1993; Biderre et al., 1994). However, the molecular knowledge of microsporidia is still rather limited to taxonomy. Although sequence data of SSUrRNA genes in several microsporidia have been published. Not only is it favor of accumulation data for molecular taxonomy of microsporidia to analyse its SSUrRNA, but also be favor of study on evolution of biology.Pathological biology and taxonomy of Microsporidia Pathogenic to The Silkworm,Bombyx Mon 1 Taxonomic character of SCM8. Host. Silkworm Bombyx Moni(larvae) Transmission. Ingestive infection. Site of infection. It only infects the epithelial cells of the midgut. Interface. Parasite undergoes entire development within a vacuole enveloped by resembling a membrane of host endoplasmic reticulum. Envelope rather closely applied to parasite plasmalemma before sporulation,then became widely separated. Envelope very delicate and mostly spores occur free in smears of disrupted cells. Development. Nuclei unpaired in all stages. Large nuclei was observed in early stages.Proliferation by multiple division of paucinucleate moniliform.Early sporont recognizable by the withdrawal of the sporont plasmalemma from the parasitophorous vacuole accompanied by an electron-dense deposit on surface of the plasmalemma.Division into sporoblasts occurred by the pinching off of buds from the highly irregular sporont body,produce. Four to about 60 sporoblasts produced. Sporoblasts mature into spores asynchronously,according to order of budding. Spore. Unincleate,Ovoid. It size tends to become small as adding of generation, 2.82 .21 X 1.89 0.13 ii m(first generation),2. 31 0. 21 X 1. 25 0. 18 ii m (third generation). Exospore thin,rugose;endospore thin.P... |
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