Longer First Introns Are a General Property of Eukaryotic Gene Structure

While many properties of eukaryotic gene structure are well characterized, differences in the form and function of introns that occur at different positions within a transcript are less well understood. In particular, the dynamics of intron length variation with respect to intron position has received relatively little attention. This study analyzes all available data on intron lengths in GenBank and finds a significant trend of increased length in first introns throughout a wide range of species. This trend was found to be even stronger when using high-confidence gene annotation data for three model organisms (Arabidopsis thaliana, Caenorhabditis elegans, and Drosophila melanogaster) which show that the first intron in the 5′ UTR is - on average - significantly longer than all downstream introns within a gene. A partial explanation for increased first intron length in A. thaliana is suggested by the increased frequency of certain motifs that are present in first introns. The phenomenon of longer first introns can potentially be used to improve gene prediction software and also to detect errors in existing gene annotations

Corporations law and policy : materials and problems

xlix, 1292 p. ; 27 cm

Teacher\u27s Manual for Lawyers, Clients and Moral Responsibility

https://scholarship.law.nd.edu/law_books/1143/thumbnail.jp

Teacher\u27s Manual for Lawyers, Clients and Moral Responsibility

https://scholarship.law.nd.edu/law_books/1143/thumbnail.jp

Teacher\u27s Manual for Lawyers, Clients and Moral Responsibility

https://scholarship.law.nd.edu/law_books/1143/thumbnail.jp

Mandated Disclosure, Stock Returns, and the 1964 Securities Acts Amendments

The 1964 Securities Acts Amendments extended the mandatory disclosure requirements that had applied to listed firms since 1934 to large firms traded Over-the-Counter (OTC). We find several pieces of evidence indicating that investors valued these disclosure requirements, two of which are particularly striking. First, a firm-level event study reveals that the OTC firms most affected by the 1964 Amendments had abnormal excess returns of about 3.5 percent in the weeks immediately surrounding the announcement that they had begun to comply with the new requirements. Second, we estimate that the most affected OTC firms had abnormal excess returns ranging between 11.5 and 22.1 percent in the period between when the legislation was initially proposed and when it went into force. These returns are adjusted for the standard four factors and are relative to NYSE/AMEX firms, matched on size and book-to-market equity, that were unaffected by the legislation. While we cannot determine how much of shareholders' gains were a transfer from insiders of these same companies, our results suggest that mandatory disclosure causes managers to focus more narrowly on maximizing shareholder value. Copyright (c) 2006 by the President and Fellows of Harvard College and the Massachusetts Institute of Technology..