The transcriptional program of meiosis and sporulation in fission yeast

Abstract

Sexual reproduction requires meiosis to produce haploid gametes, which in turn can fuse to regenerate a diploid organism. We have studied the transcriptional program that drives this developmental process in Schizosaccharomyces pombe using DNA microarrays. Here we show that hundreds of genes are regulated in successive waves of transcription that correlate with major biological events of meiosis and sporulation. Each wave is associated with specific promoter motifs. Clusters of neighboring genes (mostly close to telomeres) are co-expressed early in the process, which reflects a more global control of these genes. We find that two Atf-like transcription factors are essential for the expression of late genes and formation of spores, and identify dozens of potential Atf target genes. Comparison with the meiotic program of the distantly related Saccharomyces cerevisiae reveals an unexpectedly small shared meiotic transcriptome, suggesting that the transcriptional regulation of meiosis evolved independently in both species.

Untimely expression of gametogenic genes in vegetative cells causes uniparental disomy

“…Cufflinks was used to assemble mapped reads into the final transcriptome and to calculate Fragments Per Kilobase of transcript per Million (FPKM) mapped reads. Genes were classified as either meiotic or non-meiotic 43 . The Area proportional Euler Venn diagram for meiotic gene overlap was constructed using EulerAPE.…”

Role of the α‐glucanase Agn2p in ascus‐wall endolysis following sporulation in fission yeast

“…pombe cells have revealed that the genes involved in sporulation are periodically expressed in four successive waves (Mata et al, 2002). The first wave is a response to nutrient deprivation; the second, or early, wave occurs during the premeiotic S phase; the third, or middle, wave corresponds to meiosis I and II; and, the fourth, or late, wave coincides with ascospore formation.…”

“…Among the genes induced during the middle and late waves are those encoding enzymes involved in the synthesis of the ascospore wall, such as chitin synthase Chs1p, putative chitin deacetylase Cda1p, β-glucan synthase Bgs2p, and α-glucan synthases Mok12p and Mok13p (Arrelano et al, 2000;Liu et al, 2000;Martín et al, 2000;Garciá et al, 2006;Matsuo et al, 2005). Interestingly, the gene encoding the paralogue of the characterized endo-(1,3)-α-glucanase Agn1p, Agn2p, is also highly upregulated during the middle phase (Mata et al, 2002). Recently, we showed that, although also expressed during vegetative growth, agn2 + appears to function during sporulation (Dekker et al, 2004).…”

“…Whereas Eng1p hydrolyses (1,3)-β-glucan of the primary septum during cell separation, the role of Eng2p is unknown. Like Agn2p, Eng2p lacks a signal peptide for secretion and its expression is highly upregulated during the sporulation process (Mata et al, 2002). Given that the ascus wall probably contains substantial amounts of (1,3)-β-glucan, in addition to α-glucan, it is not unreasonable to assume that both of these structural components must be hydrolysed to release the ascospores efficiently.…”

A novel neural network approach to cDNA microarray image segmentation

“…Class 4, for example, is clearly the class that contains the noisiest spot regions while class 3 contains spots that are in high contrast to their background. Not only has the iterative training approach detected the number of classes (9) to divide the many spot regions within an image into, but it has also provided a means to classify quickly a given spot region into one of the 9 classes.…”