Date of Award:
5-1-1997
Document Type:
Thesis
Degree Name:
Master of Science (MS)
Department:
Biology
Committee Chair(s)
Nabil N. Youssef
Committee
Nabil N. Youssef
Committee
Bradley R. Kropp
Committee
Dennis L. Welker
Abstract
Four extrachromosomal DNA plasmids were isolated from the entomopathogenic fungus Ascosphaera aggregata and named as pAaL10, pAaL8, pAaL2.8, and pAaL2.6 based on their host, morphology and size. DNA hybridization results suggested that pAaL10, pAaL8, pAaL2.8, and pAaL2.6 are not homologous with pAaL, a plasmid isolated from Ascosphaera apis. Extraction of DNA from intact mitochondria followed by gel electrophoretic analysis suggests pAaL10, pAaL8, pAaL2.8, and pAaL2.6 are located within the mitochondria. From hybridization results it was concluded that each of pAaL10, pAaL8, pAaL2.8, and pAaL2.6 is not homologous to mitochondrial DNA. This implies that these plasmids are all self-replicating. Restriction digestion and electron microscopy data indicated that these plasmids are linear and double-stranded, and the sizes of pAaL10, pAaL8, pAaL2.8, and pAaL2.6 are 10, 8, 2.8, and 2.6 kilobase pairs, respectively. Endonuclease digestion suggested the presence of a terminal inverted repeat (TIR) at each end of pAaL10 and pAaL2.6. More digestion work is needed to determine the TIR of the other two linear plasmids, pAaL8 and pAaL2.8. The lack of digestion observed with exonuclease assays indicates that each of pAaL10, pAaL8, pAaL2.8, and pAaL2.6 has two blocked 5' ends. Based on nucleotide sequence and amino acid sequence data, pAaL10 has been found to have homology with pAL2-1, a linear plasmid isolated from fungus Podospora anserina. The structure of the open reading frames (ORF) of pAaL10 is similar to those of pAL2-1. Amino acid sequence data bank searching indicated that pAaL10 is possibly involved in coding DNA and RNA polymerases.
Recommended Citation
Xu, Dakun, "Isolation and Characterization of Four Linear Plasmids in Ascosphaera aggregata" (1997). Biology. 649.
https://digitalcommons.usu.edu/etd_biology/649
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