title: Abnormal micronuclear telomeres lead to an unusual cell cycle checkpoint and defects in Tetrahymena oral morphogenesis.
abstract: Telomere mutants have been well studied with respect to telomerase and the role of telomere binding proteins, but they have not been used to explore how a downstream morphogenic event is related to the mutated telomeric DNA. We report that alterations at the telomeres can have profound consequences on organellar morphogenesis. Specifically, a telomerase RNA mutation termed ter1-43AA results in the loss of germ line micronuclear telomeres in the binucleate protozoan Tetrahymena thermophila. These cells also display a micronuclear mitotic arrest, characterized by an extreme delay in anaphase with an elongated, condensed chromatin and a mitotic spindle apparatus. This anaphase defect suggests telomere fusions and consequently a spindle rather than a DNA damage checkpoint. Most surprisingly, these mutants exhibit unique, dramatic defects in the formation of the cell's oral apparatus. We suggest that micronuclear telomere loss leads to a "dynamic pause" in the program of cortical development, which may reveal an unusual cell cycle checkpoint.
authors.affiliation: Department of Biology, Lake Forest College, Lake Forest, Illinois 60045, USA. kirk@lakeforest.edu
authors.forename: Karen E
authors.initials: KE
authors.lastname: Kirk
authors.forename: Christina
authors.initials: C
authors.lastname: Christ
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: McGuire
authors.forename: Arun G
authors.initials: AG
authors.lastname: Paul
authors.forename: Mithaq
authors.initials: M
authors.lastname: Vahedi
authors.forename: Kathleen R
authors.initials: KR
authors.lastname: Stuart
authors.forename: Eric S
authors.initials: ES
authors.lastname: Cole
mesh_terms: D000818:Animals; D002453:Cell Cycle; D048631:Micronucleus, Germline / Q000235:genetics / Q000378:metabolism*; D009024:Morphogenesis; D009055:Mouth / Q000254:growth & development* / Q000378:metabolism; D016615:Telomere / Q000235:genetics / Q000378:metabolism*; D013768:Tetrahymena / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism