Duplications created by transformation in Sordaria macrospora are not inactivated during meiosis

Abstract

We present here the first report of a transformation system developed for the filamentous fungus Sordaria macrospora. Protoplasts from a ura-5 strain were transformed using the cloned Sordaria gene at a frequency of 2 x 10(-5) transformants per viable protoplast (10 per microgram of DNA). Transformation occurred by integration of the donor sequences in the chromosomes of the recipient strain. In 71 cases out of 74, integration occurred outside the ura5 locus; frequently several (two to four) copies were found at a unique integration site. Using the advantage of the spore colour phenotype of the ura5-1 marker, we have shown that the transformed phenotype is stable through mitosis and meiosis in all transformants analysed. No methylation of the duplicated sequences could be observed during meiotic divisions in the transformants.

Comparative sequence analysis of Sordaria macrospora and Neurospora crassa as a means to improve genome annotation

“…The comparisons presented here indicate that the S. macrospora genome is eminently suitable for this purpose, because it is similar enough to be readily aligned at the nucleotide level even outside of coding regions, but has aquired a sufficient degree of dissimilarity especially in non-coding regions to provide an adequate signal-to-noise enrichment for distinguishing functional from non-functional sites. Another point of interest might be the fact that in S. macrospora, no indication of RIP (repeat-induced point mutation) has been found yet (Le Chevanton et al, 1989). RIP has originally been discovered in N. crassa where it inactivates duplicated sequences during the sexual phase of the life cycle (Selker et al, 1987).…”

Eukaryotic DNA methylation as an evolutionary device

“…(7,8) Finally, fungi provide unique examples of closely related organisms that in some cases show and in others do not show methylation: whereas methylation is found in representative species of the three major fungal taxa (the zygomycetes, the ascomycetes, and the basidiomycetes), it is undetectable in several ascomycete species. (9) These include Sordaria macrospora, (10) and Saccharomyces cerevisiae, (11) which are close relatives of the methylationcontaining species Neurospora crassa (3) and Candida albicans, (12) respectively. Levels of methylation vary greatly between organisms that display this modification.…”

Gene transfer in Cryptococcus neoformans by use of biolistic delivery of DNA

“…Transformation studies of vector DNA in other fungi have demonstrated a wide range of frequencies of homologous integration. The rate is nearly 100% in Saccharomyces cerevisiae (22) and Candida albicans (17), 80% inAspergillus nidulans (34), and from 5 to 80% in Neurospora crassa depending on the host strain (5,7,15) but only 3% in Sordaria macrospora (21). Although the frequencies of these homologous recombina-* Corresponding author.…”