碩士 / 國立屏東科技大學 / 獸醫學系 / 92 / In Taiwan, yeast infection of giant freshwater prawns Macrobrachium rosenbergii is an outbreak often during the low water temperature periods in winter. The clinical signs of infection are white cloudiness of muscle tissue and hemolymph. Histopathological examinations of affected tissues revealed extensive necrosis associated with large numbers of yeast aggregates. In previous neports, the results of clinical diagnosis are differences. In this study, we identified the isolate yeast by API ID 32C, by PCR assay and 26S rDNA D1/D2 domain sequencing. The sequences of 26S rDNA from 25 isolates and 2 share strains gave 97-98% sequence identity to as Metschnikowia bicuspidata (GenBank Accession No. U44822). One share strain was identified to as Saccharomyces cerevisiae and one isolate was Candida albicans, both their sequences of 26S rDNA D1/D2 domain gave 100% sequence identity to Saccharomyces cerevisiae(GenBank Accession No. U53879) and Candida albicans (GenBank Accession No. AF156536), respectively. A PCR product of approximately 520 bp was digested by two restriction enzymes BslI and XhoI in RFLP assay, and a pair of specific primers (MB-F and MB-R) for M. bicuspidata was designed for rapid diagnosis. The numbers of yeast cells isolated from hemolymph, hepatopancreas, muscle, and gills were 9.0×109, 4.9×109, 8.0×108, and 4.5×108 CFU/gm respectively. Three isolates of M. bicuspidata, S. cerevisiae and C. albicans in experimental infections caused gross signs and histopathological changes as similar to those observed in the naturally infected prawns. The lethal doses (LD50) of these three isolates were 3.8×103, 2.0×103, and 4.3×103 CFU/prawn, respectively. The result of this study reveals M. bicuspidata is the major pathogen in yeast infection of giant freshwater prawns in Taiwan. Rapid and accurate identification pathogens of this disease can be done with RFLP by two restriction enzymes and PCR by designed specific primer pair.
| Identifer | oai:union.ndltd.org:TW/092NPUST541017 |
| Date | January 2004 |
| Creators | Chen, Yu-Chin, 陳育津 |
| Contributors | 陳石柱 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
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