title: No chromosomal clustering of housekeeping genes in the marine chordate Ciona intestinalis.
abstract: Housekeeping genes, widely expressed genes that are required for the basal function of most cell types, are clustered in the human and worm genomes. This arrangement suggests coordinate control of housekeeping gene expression at the chromosomal level. Here we examined whether this notion is applicable to a marine chordate, Ciona intestinalis. Using microarrays, we analyzed genes that were expressed in 11 organs of the adult, including the neural complex, branchial sac, esophagus, stomach, endostyle, intestine, body-wall muscle, heart, blood cells, ovary and testis. This analysis identified 158 genes that are expressed ubiquitously in these organs. These housekeeping genes could be classified into a range of Gene Ontology categories, in particular, ribosomal protein components. Of these 158 genes, we were able to map 141 genes onto the 14 pairs of the C. intestinalis chromosomes. They were distributed rather evenly over all the chromosomes, except for small clusters containing two or three genes. Therefore, the notion of chromosomal clustering of housekeeping genes is not applicable in this chordate.
authors.affiliation: Marine Genomics Unit, Okinawa Institute of Science and Technology Promotion Corporation, Onna, Okinawa 904-0412, Japan. eiichi@oist.jp
authors.forename: Eiichi
authors.initials: E
authors.lastname: Shoguchi
authors.forename: Manabu
authors.initials: M
authors.lastname: Fujie
authors.forename: Mayuko
authors.initials: M
authors.lastname: Hamada
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D002875:Chromosomes; D002938:Ciona intestinalis / Q000235:genetics*; D020224:Expressed Sequence Tags; D005786:Gene Expression Regulation / Q000502:physiology; D020043:Genes, Essential / Q000235:genetics*