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KAR4, the yeast homolog of the mammalian mRNA N6A-methyltransferase complex component METTL14, is required for two disparate developmental programs in Saccharomyces cerevisiae: mating and meiosis. To understand KAR4's role in yeast mating and meiosis, we used a genetic screen to isolate 25 function-specific mutant alleles, which map to non-overlapping surfaces on a predicted structure of the Kar4 protein (Kar4p). Most of the mating-specific alleles (Mat-) abolish Kar4p's interaction with the transcription factor Ste12p, indicating that Kar4p's mating function is through Ste12p. In yeast, the mRNA methyltransferase complex was previously defined as comprising Ime4p (Kar4p's paralog and the homolog of mammalian METTL3), Mum2p (homolog of mammalian WTAP), and Slz1p (MIS), but not Kar4p. During meiosis, Kar4p interacts with Ime4p, Mum2p, and Slz1p. Moreover, cells lacking Kar4p have highly reduced levels of mRNA methylation during meiosis indicating that Kar4p is a key member of the methyltransferase complex, as it is in humans. Analysis of kar4Δ/Δ and 7 meiosis-specific alleles (Mei-) revealed that Kar4p is required early in meiosis, before initiation of S-phase and meiotic recombination. High copy expression of the meiotic transcriptional activator IME1 rescued the defect of these Mei- alleles. Surprisingly, Kar4p was also found to be required at a second step for the completion of meiosis and sporulation. Over-expression of IME1 in kar4Δ/Δ permits pre-meiotic S-phase, but most cells remained arrested with a monopolar spindle. Analysis of the function-specific mutants revealed that roughly half became blocked after premeiotic DNA synthesis and did not sporulate (Spo-). Loss of Kar4p's Spo function was suppressed by overexpression of RIM4, a meiotic translational regulator. Overexpression of IME1 and RIM4 together allowed sporulation of kar4Δ/Δ cells. Taken together, these data suggest that Kar4p regulates meiosis at multiple steps, presumably reflecting requirements for methylation in different stages of meiotic gene expression. Author summary: In yeast, KAR4 is required for mating and meiosis. A genetic screen for function-specific mutations identified 25 alleles that map to different surfaces on a predicted structure of the Kar4 protein (Kar4p). The mating-specific alleles interfere with Kar4p's ability to interact with the transcription factor Ste12p, its known partner in mating. The meiosis-specific alleles revealed an independent function: Kar4p is required for entry into meiosis and initiation of S-phase. During meiosis, Kar4p interacts with all components of the mRNA methyltransferase complex and kar4Δ/Δ mutants have greatly reduced levels of mRNA methylation. Thus, Kar4p is a member of the yeast methyltransferase complex. Overexpression of the meiotic transcriptional activator IME1 rescued the meiotic entry defect but did not lead to sporulation, implying that Kar4p has more than one meiotic function. Suppression by Ime1p overexpression led to arrest after premeiotic DNA synthesis, but before sporulation. Loss of Kar4's sporulation function can be suppressed by overexpression of a translation regulator, Rim4p. Overexpression of both IME1 and RIM4 allowed sporulation in kar4Δ/Δ cells. [ABSTRACT FROM AUTHOR]

Health impact assessment (HIA) methods are used to evaluate the impact on health of policies and projects in community design, transportation planning, and other areas outside traditional public health concerns. At an October 2004 workshop, domestic and international experts explored issues associated with advancing the use of HIA methods by local health departments, planning commissions, and other decision-makers in the United States. Workshop participants recommended conducting pilot tests of existing HIA tools, developing a database of health impacts of common projects and policies, developing resources for HIA use, building workforce capacity to conduct HIAs, and evaluating HIAs. HIA methods can influence decisionmakers to adjust policies and projects to maximize benefits and minimize harm to the public's health. doi:10.2105/AJPH.2005.069880)

No abstract available for this article. [ABSTRACT FROM PUBLISHER]