title: Gene expression assays for actin, ubiquitin, and three microsatellite-encoding genes in Helianthus annuus (Asteraceae).
abstract: OBJECTIVE
  The "tuning knob" model of King et al. (Endeavor 21: 36-40, 1997) postulates that microsatellite mutations can alter phenotypes in a stepwise fashion. Some proposed mechanisms involve regulation of gene expression. To study the effect of microsatellites harbored in untranslated regions on gene expression in Helianthus annuus, we have developed TaqMan assays for three microsatellite-encoding genes, and two constitutively expressed genes, actin and ubiquitin, to serve as standards.
  
  
  RESULTS
  All five TaqMan assays yielded strong log-linear relationships between cycle threshold (C(T)) values and cDNA concentrations (R(2) = 0.98-0.99). Standard curves were based on five concentrations for each of five individuals. Efficiencies ranged from 0.83 to 1.03.
  
  
  CONCLUSIONS
  The developed tools will allow for relative quantification of gene expression across individuals. Genotyping these loci will allow for testing the "tuning knob" hypothesis. Further, the actin and ubiquitin assays should be generally applicable to gene expression studies in H. annuus.
authors.affiliation: Department of Biological Sciences, Mississippi State University, 212 Harned Hall, 295 Lee Boulevard, Starkville, Mississippi 39762, USA. sp456@msstate.edu
authors.forename: Sreepriya
authors.initials: S
authors.lastname: Pramod
authors.forename: Katharyn E
authors.initials: KE
authors.lastname: Downs
authors.forename: Mark E
authors.initials: ME
authors.lastname: Welch
mesh_terms: D000199:Actins / Q000235:genetics* / Q000378:metabolism; D000704:Analysis of Variance; D020869:Gene Expression Profiling / Q000379:methods*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D006368:Helianthus / Q000235:genetics; D018895:Microsatellite Repeats / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D025801:Ubiquitin / Q000235:genetics* / Q000378:metabolism
chemical_list: D000199:Actins; D012333:RNA, Messenger; D025801:Ubiquitin