Caenorhabditis elegans levamisole resistance genes lev-1, unc-29, and unc-38 encode functional nicotinic acetylcholine receptor subunits - PubMed (original) (raw)

Fig. 1.

Structures of the_lev-1_, unc-29, and unc-38_nAChR subunit genes. A, lev-1 structure. The position of lev-1 on the genetic map of chromosome IV is shown in relation to nearby genetic markers. The relative contig positions on the physical map of cosmids W07H6, C43C9, and B0564 and λ phage clones JF#WA10 and JF#WA18 derived from the_lev-1 region are indicated. The genomic organization of the lev-1 gene is shown. Restriction enzyme sites are indicated to define possible limits of mutations: R,Eco_RI; S, Sal_I;H, Hin_dIII; X,Xho_I; and B, Bam_HI. Mutant alleles found to have substantial DNA sequence rearrangements or Tc1 insertions are diagrammed. The open bar for_x548 represents a deletion with a range of end points indicated. x416, x427, x438, and_x566 represent complex rearrangements, mostly insertions of the sizes indicated, affecting the restriction fragments spanned by the bar shown for each mutation. For_x504, x508, and x562, the positions of 1.6 kb Tc1 insertions are indicated by_arrows. For e211, e289,x21, x38, x61, x400, and_x505, no DNA differences were detected. GenBank entryX98601 gives the DNA sequence of lev-1. B,unc-29 structure. The position of _unc-29_on the genetic map of chromosome I is shown in relation to nearby genetic markers. The relative contig positions on the physical map of cosmids C45D10, C11C3, and C34D2 and λ phage clones ZZ#1, ZZ#2, and JF#WA33 derived from the unc-29 region are indicated. The genomic organization of the unc-29 gene is shown. Restriction enzyme sites: R, _Eco_RI;S, _Sal_I; and H,Hin_dIII. The positions of a mutation caused by DNA rearrangement and of six mutations caused by apparent transposon insertion are shown relative to the Eco_RI fragments that span the unc-29 gene. The sizes of the apparent inserts found were 1.6 kb each for x513, x522,x544, x545, and x554 and 2.5 kb for x520. The inserts of x520,x544, and x554 were lost in revertants, and the insert of x513 hybridized to Tc1. The exact nature and extent of the x415 mutation are unknown, but at least several hundred bases near the 3′ end of the coding seem to be involved (see Materials and Methods). For x401,x417, x429, and x433, noDNA differences were detected. The DNA sequence of_unc-29 is given by GenBank entry U81144.C, Structure of the unc-38 nAChR α subunit gene. The position of unc-38 on the genetic map of chromosome I is shown in relation to nearby genetic markers. The relative contig positions on the physical map of cosmids C09C3, B0241, and C04E4 and λ phage clones ZZ#11 and ZZ#15 are indicated. The genomic organization of the unc-38 gene is shown. Restriction enzyme sites: P, Pst_I; and_H, Hin_dIII. Mutations associated with Tc1 insertion or DNA rearrangements within the Hin_dIII fragment spanning the unc-38 gene are indicated. For_x402, x404, x414, and_x511, no DNA differences were found in this fragment. Other than causing a size alteration of the 3.2 kb_Hin_dIII fragment, the exact nature and extent of the_x411 and x419 mutations are unknown. The DNA sequence of unc-38 is given by GenBank entryX98599.