How were map positions determined for the annotations?
All the predicted genes have now been incorporated into FlyBase with inferred cytology. The inference system we have used is to take the estimates which Sorsa published a few years ago of the size in kb of each polytene band. These estimates can be summed to give the length (according to Sorsa) in kb of a region between two very well-mapped genes (“anchors”) that are also identified on the genome. The genome sequence gives a different number for that length, of course. So we then just applied a scaling factor, i.e. we calculated the cytology of each genome gene in the region between the anchors by interpolation from its sequence coordinates. The anchors we chose are spaced about a number division apart. The scaling works out slightly different for each inter-anchor region, of course, and we reckon that even in the middle of a region the error should never be more than a couple of bands. The dataset is based on the genome coordinates, which includes only the assemblable and mappable euc
