Fig. 2

Isolation of the two of hearts Gene

(A) Positional cloning of toh. Direction of the chromosomal walk is indicated with black arrows above the marker names. Markers used for mapping are indicated above the line representing the genomic region. The numbers of recombination events out of 2394 meioses found at each marker are indicated below the genomic region. A magnification of the critical region depicts portions of six open-reading frames (open arrows) in the identified genetic interval, including the previously cloned locus liebeskummer/reptin. The critical region contains two spinster-like genes, one of which was identified as toh (gray filled arrow) and the other of which we here name spinl3.

(B) Schematic diagram of Toh proteins produced from each allele. Arrows point to the site affected in the mutant alleles. Transmembrane domains are indicated in blue, and the predicted translated intronic sequence in the s8 allele is indicated in red. Numbers also identify the individual transmembrane domains.

(C) Injection of a splice blocking MO against toh into WT embryos phenocopies the toh mutations, leading to pericardial edema (arrow) and blistering in the tail (arrowhead).