title: Mendelian inheritance pattern and high mutation rates of microsatellite alleles in the diatom Pseudo-nitzschia multistriata.
abstract: The diatom Pseudo-nitzschia multistriata exhibits a diplontic life cycle composed of an extensive phase of vegetative cell division and a brief phase of sexual reproduction. To explore genotypic stability, we genotyped seven polymorphic microsatellite loci in 26 monoclonal strains over 3-16 months in a culture maintenance regime. Moreover, to assess inheritance patterns of the microsatellite alleles, we genotyped 246 F1 strains resulting from four mating experiments between parental strains of know genotype. Results generally conformed expectations according to Mendelian inheritance patterns, but deviations were detected indicating mutations during sexual reproduction. A total of forty-two mutations were detected in the clonal cultures over time. Microsatellites with more core-repeats accumulated mutations faster. The mutation rate varied significantly across loci and strains. A binomial mass function and a computer simulation showed that the mutation rate was significantly higher during the first months of culture (μ≈3×10(-3) per locus per cell division) and decreased to μ≈1×10(-3) in the strains kept for 16 months. Our results suggest that genetic mutations acquired in both the vegetative phase and sexual reproduction add to the allelic diversity of microsatellites, and hence to the genotypic variation present in a natural population.
authors.affiliation: Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy. Sylvie.Tesson@biol.lu.se
authors.forename: Sylvie V M
authors.initials: SV
authors.lastname: Tesson
authors.forename: Christophe
authors.initials: C
authors.lastname: Legrand
authors.forename: Cock
authors.initials: C
authors.lastname: van Oosterhout
authors.forename: Marina
authors.initials: M
authors.lastname: Montresor
authors.forename: Wiebe H C F
authors.initials: WH
authors.lastname: Kooistra
authors.forename: Gabriele
authors.initials: G
authors.lastname: Procaccini
mesh_terms: D000483:Alleles; D002455:Cell Division; D003198:Computer Simulation; D017377:Diatoms / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D042822:Genomic Instability; D040582:Inheritance Patterns; D018895:Microsatellite Repeats; D059645:Mutation Rate