Figure 1.
Schematic of crossing strategy used to generate snails that segregate for chirality genotype.
Genotypes of snails are labelled as DD, Dd and dd, with the phenotypes labelled as sin and dex. The phenotype of offspring is determined by the maternal genotype (see main text).
Figure 2.
Genetic map of the region containing the chirality locus, D, with numbers of recombinants recovered from genetically sinistral (dd) and dextral snails (DD or Dd.)
It was not possible to determine the precise number of recombinants in the interval between marker rad4 and chirality locus D in DD or Dd snails, because of uncertainty as to the chirality genotype of recombinants.
Table 1.
Summary of genotypes of all individuals.
Figure 3.
Pachytene-FISH mapping of the chirality locus.
Pachytene-FISH was performed using BACs containing RAD-Seq locus rad7 (white; BAC clone G1A, 137 kb), rad4 (red; R6F, 129 kb) and rad5 (green; B2D, 97 kb). All three BACs show hybridisation to the same bivalent chromosome. Chromosomes are counterstained with 4′,6-diamidino-2-phenylindole (DAPI; blue).
Figure 4.
Fibre FISH using BACs that bound the chirality locus.
The gap between the hybridisation signal from BAC clones containing loci rad4 (red, R6F, 129 kb) and rad5 (green, B2D, 97 kb) is at least 4 to 5 times the length of a BAC clone. The preparation is counterstained with 4′,6-diamidino-2-phenylindole (DAPI; blue). In this example from a genetically dextral snail, an interphase, meiotic cell is also visible, showing signal from hybridisation to both BACs.