The purpose of this note is to explain a confusing situation regarding sqh-GFP constructs, insertions and stocks. Royou et al. (2004; FBrf0167867) described two constructs for tagging the regulatory light chain of myosin (=sqh) with GFP. P{sqh-GFP.RLC} (FBtp0040965) placed GFP on the C-terminus of sqh and P{GFP-sqh.RLC} (FBtp0081837) placed GFP on the N-terminus of sqh. The P{GFP-sqh.RLC} construct did not work as well as P{sqh-GFP.RLC}, so it was not used extensively in the paper. Roger Karess' lab, where the constructs were made, discarded P{GFP-sqh.RLC} stocks without sending them to other labs. They used two insertions of P{sqh-GFP.RLC} extensively: insertion 42 on the second chromosome and insertion 40 on the third chromosome. Insertion 42 was also at times called C-42. The Bloomington Stock Center has been distributing stocks under the following stock numbers, genotypes and chromosomal locations: 42234 y1 w* cv1 sqhAX3; P{w+mC=GFP-sqh.RLC}40 1;3 42235 y1 w* cv1 sqhAX3; P{w+mC=sqh-GFP.RLC}C-42 1;2 We recently found that the insertion in stock 42234 is located on the second chromosome. Given the information above, it must, if fact, carry P{sqh-GFP.RLC}C-42. To avoid confusion, we will now distribute this stock under the following stock number, genotype and chromosomal location: 57144 y1 w* cv1 sqhAX3; P{w+mC=sqh-GFP.RLC}2 1;2 Note that P{GFP-sqh.RLC}40 was never listed as an insertion in FlyBase; instead, entries existed for P{sqh-GFP.RLC}C-42 (FBti0073027) and P{sqh-GFP.RLC}40 (FBti0150058). The fact that the construct symbol associated with insertion 40 did not match in FlyBase insertion entry FBti0150058 and stock 42234 further contributed to the confusion. We also found that stock 42235 carries insertions on both chromosomes 2 and 3; consequently, it must correspond to a stock from the Karess lab, where insertions 40 and 42 were combined. To avoid confusion, we will now distribute a stock carrying only the third chromosome insertion under the following stock number, genotype and chromosomal location: 57145 y1 w* cv1 sqhAX3; P{w+mC=sqh-GFP.RLC}3 1;3 The new stocks went into public distribution late August 2014. -- Kevin Cook, Ph.D. Bloomington Drosophila Stock Center http://flystocks.bio.indiana.edu
