This study describes comprehensive polling of transcription start and termination sites and analysis of previously unidentified full-length complementary DNAs derived from the mouse genome. We identify the 5' and 3' boundaries of 181,047 transcripts with extensive variation in transcripts arising from alternative promoter usage, splicing, and polyadenylation. There are 16,247 new mouse protein-coding transcripts, including 5154 encoding previously unidentified proteins. Genomic mapping of the transcriptome reveals transcriptional forests, with overlapping transcription on both strands, separated by deserts in which few transcripts are observed. The data provide a comprehensive platform for the comparative analysis of mammalian transcriptional regulation in differentiation and development.

In the effort to prepare the mouse full-length cDNA encyclopedia, we previously developed several techniques to prepare and select full-length cDNAs. To increase the number of different cDNAs, we introduce here a strategy to prepare normalized and subtracted cDNA libraries in a single step. The method is based on hybridization of the first-strand, full-length cDNA with several RNA drivers, including starting mRNA as the normalizing driver and run-off transcripts from minilibraries containing highly expressed genes, rearrayed clones, and previously sequenced cDNAs as subtracting drivers. Our method keeps the proportion of full-length cDNAs in the subtracted/normalized library high. Moreover, our method dramatically enhances the discovery of new genes as compared to results obtained by using standard, full-length cDNA libraries. This procedure can be extended to the preparation of full-length cDNA encyclopedias from other organisms.It has been tempting to prepare and use full-length cDNA libraries (Kato et al.

We report the construction of the mouse full-length cDNA encyclopedia, the most extensive view of a complex transcriptome, on the basis of preparing and sequencing 246 libraries. Before cloning, cDNAs were enriched in full-length by Cap-Trapper, and in most cases, aggressively subtracted/normalized. We have produced 1,442,236 successful 3Ј-end sequences clustered into 171,144 groups, from which 60,770 clones were fully sequenced cDNAs Cold Spring Harbor Laboratory Press on May 10, 2018 -Published by genome.cshlp.org Downloaded from annotated in the FANTOM-2 annotation. We have also produced 547,149 5Ј end reads, which clustered into 124,258 groups. Altogether, these cDNAs were further grouped in 70,000 transcriptional units (TU), which represent the best coverage of a transcriptome so far. By monitoring the extent of normalization/subtraction, we define the tentative equivalent coverage (TEC), which was estimated to be equivalent to >12,000,000 ESTs derived from standard libraries. High coverage explains discrepancies between the very large numbers of clusters (and TUs) of this project, which also include non-protein-coding RNAs, and the lower gene number estimation of genome annotations. Altogether, 5Ј-end clusters identify regions that are potential promoters for 8637 known genes and 5Ј-end clusters suggest the presence of almost 63,000 transcriptional starting points. An estimate of the frequency of polyadenylation signals suggests that at least half of the singletons in the EST set represent real mRNAs. Clones accounting for about half of the predicted TUs await further sequencing. The continued high-discovery rate suggests that the task of transcriptome discovery is not yet complete.[Supplemental material available online at www.genome.org.]One of the primary goals of genome sequencing projects is to identify the genome sequences that are transcribed into functional mRNAs, so that full-length cDNAs can be isolated to allow further downstream biology, and functional and structural genomics. The limitations of a priori genome annotation dictate that the transcriptome needs to be identified experimentally via cDNA cloning and sequencing. Although expressed sequence tags (ESTs) (Adams et al. 1991(Adams et al. , 1995Hillier et al. 1996;Marra et al. 1999;Kargul et al. 2001) and ORESTES (Camargo et al. 2001) have been extremely valuable for new gene discovery, these approaches have not allowed highthroughput recovering of full-length cDNA clones nor definition of protein sequence derived from actual cDNA clones. To overcome such problems, we undertook from the year 1995, a strategic project aimed at the comprehensive collection of at least one full-length cDNA derived from each mouse gene, a strategy that is recently becoming useful in similar projects to collect full-length gene collections (Stapleton et al. 2002;Strausberg et al. 2002).Because of the limited processivity of reverse transcriptase and other limitations, standard cDNA libraries generally contain a majority of truncated transcripts. The introductio...

The RIKEN Mouse Gene Encyclopaedia Project, a systematic approach to determining the full coding potential of the mouse genome, involves collection and sequencing of full-length complementary DNAs and physical mapping of the corresponding genes to the mouse genome. We organized an international functional annotation meeting (FANTOM) to annotate the first 21,076 cDNAs to be analysed in this project. Here we describe the first RIKEN clone collection, which is one of the largest described for any organism. Analysis of these cDNAs extends known gene families and identifies new ones.

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