RÉSUMÉ
In this study, the "milky disease" model of Eriocheir sinhensis was constructed via intramuscular injection with the pathogenic yeast Metschnikowia bicuspidata. The dynamic pathological changes of E. sinensis after injection were elucidated with two staining methods (haemotoxylin-eosin and alcian blue periodic acid-Schiff) and fluorescence in situ hybridization technology. Anatomical observation revealed three stages of the "milky disease": no clinical signs (1-4 days after infection), the appearance of signs of disease (5-7 days), and significant liquefaction (10 days). Histological observation also revealed three stages of the disease: yeast diffusion (1-2 days after infection), yeast slow development (3-4 days), and yeast rapid proliferation (5 days). And FISH technique was suitable for the early detection of infection with M. bicuspidata in E. sinensis. We found that M. bicuspidata spread to the whole body of the crab through the haemolymph and developed into fungal septicaemia. These results elucidate the systemic pathological characteristics of "milky disease" in E. sinensis and suggest the pathogenic mechanism of M. bicuspidata.
RÉSUMÉ
The outbreak of milky disease of Chinese mitten crab caused by M. bicuspidata seriously restricted the development of the crab industry. In this study, the mitochondrial genome sequence of M. bicuspidata was assembled, annotated, and further analyzed. The results indicated that the complete mitochondrial genome of M. bicuspidata was 75,095 bp, which contained two rRNAs, 23 tRNAs, and 13 protein-coding genes. The phylogenetic tree of 13 yeasts based on the complete mitochondrial genome was constructed which showed that M. bicuspidata (accession number OK514652) and M. bicuspidata (accession number MW147605.1) were clustered in a clade. To sum up, our research results would further provide essential data for the systematics and evolution study of M. bicuspidata.