GENOME ORGANIZATION IN BEAUVERIA-BASSIANA - ELECTROPHORETIC KARYOTYPE, GENE-MAPPING, AND TELOMERIC FINGERPRINT

Using telomeric fingerprint and pulsed-field gel electrophoresis, we h ave analyzed the chromosomal organization among nine entomogenous Beau veria bassiana isolates, A heterologous telomeric probe established th at the minimum number of chromosomes was between seven and eight among isolates, Chromosomal DNA was electrophoresed by using contour-clampe d homogenous electric field (CHEF) gel electrophoresis, Five to eight chromosomal bands were separated among isolates, Substantial variation in band intensity suggested the presence of some chromosome doublets, The deduced karyotypes were in agreement with the minimum chromosome number reported from telomeric fingerprints, The minimum total genome size was estimated to range from 34.3 to 44.1 Mb. Significant chromoso me length polymorphism was observed in karyotypes in the species B, ba ssiana except within isolates from one insect, Ostrinia nubilalis, Spe cific hybridization to chromosomes on CHEF gels was obtained by using homologous genes for proteinase 1, 28S rDNA, beta-tubulin, histone 4, nitrate reductase, and the mitochondrial small rDNA. The mitochondrial DNA had a slow mobility in comparison to its circular size, probably because of the presence of very long linear molecules. Comparison of k aryotype profiles following Southern analysis demonstrated a very flex ible chromosomal organization among isolates from different origins an d has confirmed the similarities within O. nubilalis isolates. (C) 199 6 Academic Press, Inc.