Abstract

The germline genome in hypotrichous ciliates has undergone two profound modifications during evolution: the insertion of noncoding sequences called IESs into most or scrambled configuration. These modifications are eliminated from germline DNA when a germline nucleus (micronucleus) develops into a somatic nucleus (macronucleus) after cell mating. Insertion and removal of IESs, mutation of IES sequence and length, and shifting of position of IESs in genes are to be tracked during evolution by comparing the structure of genes encoding actin I, alpha and beta telomere-binding proteins, and DNA polymerase alpha in 11 hypotrich species spanning a broad range of phylogenetic distance. A mutational model of IES sliding along DNA will be tested by mutagenizing cells with ultraviolet light, ethidium bromide, and methyl nitrosourea and monitoring the positions of IESs in both nonscrambled and scrambled germline genes. Transformation by DNA injection will be used to test the hypothesis that DNA processing in the germline nucleus (micronuleus) during development is guided by DNA sequence information from the old somatic nucleus (macronucleus). The organization of the macronuclear and micronuclear versions of two additional genes, encoding a telomerase subunit and telomerase RNA, will be analyzed in one hypotrich. The experiments deal with the general problem of how an organism can manipulate its own DNA.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM056161-01
Application #
2372628
Study Section
Molecular Cytology Study Section (CTY)
Project Start
1997-08-01
Project End
2001-07-31
Budget Start
1997-08-01
Budget End
1998-07-31
Support Year
1
Fiscal Year
1997
Total Cost
Indirect Cost

  Institution

Name
University of Colorado at Boulder
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
City
Boulder
State
CO
Country
United States
Zip Code
80309

  Publications

Dalby, Andrew B; Prescott, David M (2004) The scrambled actin I gene in Uroleptus pisces. Chromosoma 112:247-54
Hewitt, Elizabeth A; Muller, Kirsten M; Cannone, Jamie et al. (2003) Phylogenetic relationships among 28 spirotrichous ciliates documented by rDNA. Mol Phylogenet Evol 29:258-67
Prescott, David M; Ehrenfeucht, A; Rozenberg, G (2003) Template-guided recombination for IES elimination and unscrambling of genes in stichotrichous ciliates. J Theor Biol 222:323-30
Croft, Katie E; Dalby, Andrew B; Hogan, Daniel J et al. (2003) Macronuclear molecules encoding actins in spirotrichs. J Mol Evol 56:341-50
Prescott, David M; Prescott, Jason D; Prescott, Ryan M (2002) Coding properties of macronuclear DNA molecules in Sterkiella nova (Oxytricha nova). Protist 153:71-7
Murti, K G; Prescott, D M (2002) Topological organization of DNA molecules in the macronucleus of hypotrichous ciliated protozoa. Chromosome Res 10:165-73
Hogan, D J; Hewitt, E A; Orr, K E et al. (2001) Evolution of IESs and scrambling in the actin I gene in hypotrichous ciliates. Proc Natl Acad Sci U S A 98:15101-6
Murti, K G; Prescott, D M (1999) Telomeres of polytene chromosomes in a ciliated protozoan terminate in duplex DNA loops. Proc Natl Acad Sci U S A 96:14436-9
Prescott, D M (1999) The evolutionary scrambling and developmental unscrambling of germline genes in hypotrichous ciliates. Nucleic Acids Res 27:1243-50
Prescott, D M (1999) Evolution of DNA organization in hypotrichous ciliates. Ann N Y Acad Sci 870:301-13

Showing the most recent 10 out of 12 publications