The choanoflagellate Monosiga brevicollis karyotype revealed by the genome sequence: telomere-linked helicase genes resemble those of some fungi.
The approximately 42 Mbp assembled genome sequence for the choanoflagellate Monosiga brevicollis reveals that most of the large scaffolds of 300-2,600 kb represent entire chromosomes or chromosome arms. Telomeres are partially assembled at the termini of 37 scaffolds, while another 43 scaffolds end in telomere-associated regions containing distinctive gene sets. Potential centromeric regions were identified on 39 scaffolds. Together, these observations suggest a karyotype of approximately 40 metacentric and submetacentric chromosomes averaging 1 Mbp in size. Genes encoding RecQ family DNA helicases, along with ankyrin-domain proteins and serine/threonine kinases, are associated with most telomeres, a feature shared with some fungi. This telomere-linked helicase gene arrangement might be ancestral to both fungi and choanoflagellates in the super-kingdom Opisthokonta; however, the great lability of telomere architecture suggests that it could also be a convergent feature.
Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. hughrobe@uiuc.edu
Hugh M
HM
Robertson
D056897:Choanoflagellata / Q000201:enzymology* / Q000235:genetics*; D004265:DNA Helicases / Q000235:genetics*; D018503:Genome, Protozoan; D007621:Karyotyping; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D016615:Telomere / Q000235:genetics*
D004265:DNA Helicases