Functional Genomics

A panoramic view of yeast noncoding RNA processing. Peng, W. -T. et al. Cell 113, 919–933 (2003)

Cells are full of non-coding RNAs — in yeast they make up 95% of the nucleic-acid content. Yet the processing events that are involved in the maturation of these RNAs are not completely understood. Building on previous functional genomic and proteomic studies, the authors used microarray analysis to monitor the abundance and processing of non-coding RNAs in 468 mutant yeast strains. The results confirmed that many uncharacterized yeast proteins are involved in non-coding RNA biogenesis.

Developmental Genetics

Cell fate decisions within the mouse organizer are governed by graded Nodal signals. Vincent, S. D. et al. Genes Dev. 17, 1646–1662 (2003)

Nodal, BMP and WNT regulate the patterning of the streak and the formation of midline-organizing tissues, but their specific contributions in different cell lines were poorly defined, until now. Using a conditional inactivation strategy, the authors show that removing Smad2 affects the anterior definitive endoderm and precordal-plate progenitors, but not the primitive streak. They also show that Nodal activity in the posterior epiblast is required for the correct development of the anterior streak, and that both copies of Smad3 are required in Smad2-deficient mice to specify all axial midline tissues.

Human Genetics

Genome scan meta analysis of schizophrenia and bipolar disorder. Part I: methods and power analysis. Levinson, D. F. et al. Am. J. Hum. Genet. 73, 17–34 (2003)

This is the first of three papers that discuss genome scan meta-analysis (GSMA) and its unbiased application to complex disorders. Levinson et al. examine the power of GSMA to determine linkage and identify the thresholds of significance for application to actual meta-analyses. In the same issue, Lewis et al. and Segurado et al. use GSMA to study schizophrenia and bipolar disorder.

Computational Biology

Computational discovery of internal micro-exons. Volfovsky, N. et al. Genome Res. 13, 1216–1221 (2003)

One area of annotating exon–intron structure that remains difficult is the identification of micro-exons — short exons of up to 25 bp that are usually conserved between species and sometimes assist in alternative splicing events. Using their spliced alignment-correction procedure, the authors detected 224 previously unidentified micro-exons in four complete genomes — human, worm, fly and Arabidopsis. This new algorithm should help improve our understanding of genome variability and splicing machinery.