Autosomal genes of autosomal/X-linked duplicated gene pairs and germ-line proliferation in Caenorhabditis elegans.
We report molecular genetic studies of three genes involved in early germ-line proliferation in Caenorhabditis elegans that lend unexpected insight into a germ-line/soma functional separation of autosomal/X-linked duplicated gene pairs. In a genetic screen for germ-line proliferation-defective mutants, we identified mutations in rpl-11.1 (L11 protein of the large ribosomal subunit), pab-1 [a poly(A)-binding protein], and glp-3/eft-3 (an elongation factor 1-alpha homolog). All three are members of autosome/X gene pairs. Consistent with a germ-line-restricted function of rpl-11.1 and pab-1, mutations in these genes extend life span and cause gigantism. We further examined the RNAi phenotypes of the three sets of rpl genes (rpl-11, rpl-24, and rpl-25) and found that for the two rpl genes with autosomal/X-linked pairs (rpl-11 and rpl-25), zygotic germ-line function is carried by the autosomal copy. Available RNAi results for highly conserved autosomal/X-linked gene pairs suggest that other duplicated genes may follow a similar trend. The three rpl and the pab-1/2 duplications predate the divergence between C. elegans and C. briggsae, while the eft-3/4 duplication appears to have occurred in the lineage to C. elegans after it diverged from C. briggsae. The duplicated C. briggsae orthologs of the three C. elegans autosomal/X-linked gene pairs also display functional differences between paralogs. We present hypotheses for evolutionary mechanisms that may underlie germ-line/soma subfunctionalization of duplicated genes, taking into account the role of X chromosome silencing in the germ line and analogous mammalian phenomena.
Maciejowski
John
J
Department of Biology, New York University, NY 10003, USA.
Ahn
James Hyungsoo
JH
Cipriani
Patricia Giselle
PG
Killian
Darrell J
DJ
Chaudhary
Aisha L
AL
Lee
Ji Inn
JI
Voutev
Roumen
R
Johnsen
Robert C
RC
Baillie
David L
DL
Gunsalus
Kristin C
KC
Fitch
David H A
DH
Hubbard
E Jane Albert
EJ
D000818:Animals; D002107:Caenorhabditis / Q000235:genetics / Q000378:metabolism; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry; D049109:Cell Proliferation; D017931:DNA Primers / Q000737:chemistry; D019143:Evolution, Molecular; D020440:Gene Duplication; D020868:Gene Silencing; D008040:Genetic Linkage; D016678:Genome; D005838:Genotype; D018095:Germ-Line Mutation; D049452:Green Fluorescent Proteins; D015801:Helminth Proteins / Q000737:chemistry; D008954:Models, Biological; D008957:Models, Genetic; D009154:Mutation; D016366:Open Reading Frames; D010641:Phenotype; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D034622:RNA Interference; D012269:Ribosomal Proteins / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D014960:X Chromosome / Q000648:ultrastructure
D029742:Caenorhabditis elegans Proteins; D017931:DNA Primers; D015801:Helminth Proteins; D012269:Ribosomal Proteins; C027624:ribosomal protein L11; D049452:Green Fluorescent Proteins