Gene expression during development of Blastocladiella emersonii

• Published in: Experimental mycology Vol. 8; no. 2; pp. 132 - 145
• Main Authors: Johnson, Steven A., Lovett, James S.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.01.1984; Academic Press
• Subjects: Biological and medical sciences; Blastocladiella emersonii; Classical genetics, quantitative genetics, hybrids; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; development; gene expression; Blastocladiella emersonii; polysomal RNA; Fungi; Culture medium; Ribosomal RNA; Sporulation; Germination; Microorganism culture; Development; Primary structure; Gene expression; Polysome; Thallophyta
• ISSN: 0147-5975; 1878-4399
• DOI: 10.1016/0147-5975(84)90030-6

To evaluate gene expression during sporulation and early development of the aquatic fungus Blastocladiella emersonii, the nucleotide sequence complexity of the polysomal RNA has been measured at different stages. To assess the effect of medium composition on gene expression, similar experiments were completed during early development in a range of simple to complex media. The polysomal RNA sequence complexity was measured by hybridization with single-copy tracer DNA and with a complex class-enriched cDNA fraction copied from the stored zoospore poly(A +)RNA. Forty-four to eighty-six percent (8.2 × 10 6 to 16 × 10 6 nucleotides) of the single-copy DNA sequence complexity was found on polysomes, depending upon the stage examined or the medium used, compared to 42.5% (8 × 10 6 nucleotides) in the stored RNA pool of zoospores. The highest levels of complexity occurred during the two periods of active differentiation, sporulation and germination. During starvation-induced sporulation, and average of 82% of the total asymmetrically transcribed complexity was expressed; half of this complexity was lost prior to the completion of zoospore differentiation and was missing from the zoospore-stored RNA pool. During the first 30 min of zoospore germination the level of sequence complexity increased by 46 to 66% over the zoospore level, depending upon the medium used. The polysomal RNA complexity then decreased by a nearly equal amount between 30 and 60 min when the cells entered the growth phase. An inverse relationship was found between the richness of the medium and the level of sequence complexity found on polysomes. The data indicate that sequences representative of most of the zoospore-stored poly(A+)RNA were expressed at all other stages and maintained by turnover and resynthesis. In addition, significant numbers of new sequences were also expressed, particularly during stages of active differentiation. Cells that germinated and completed early development in an inorganic starvation medium showed a marked loss of the middle and high abundance classes of poly(A +)RNA and slight enrichment for the low abundance class.