Translocation breakpoints often disrupt genes. About a third of our stocks with translocations are maintained for their breakpoint-induced mutations. They are shown here.

The following stocks carry translocations that juxtapose euchromatic and heterochromatic regions and lead to position-effect variegation of the genes noted.

Reciprocal translocations between two balancer chromosomes assure that the balancers are always inherited together, because alternate segregation in meiosis I produces euploid progeny that live while adjacent segregation produces aneuploidy progeny that die.

T(2;3)ap[Xa] was generated between progenitor chromosomes with inversions, so the resulting chromosomes have several breakpoints which effectively balance regions of 2R and 3R:

T(1;2)OR64 and T(1;3)OR60 are translocations associated with dominant male lethality. They are useful for maintaining stocks of dominant female sterile mutations.

Historically, a major use of reciprocal translocations between the Y chromosome and another chromosome was generating chromosomal deletions and duplications by combining translocation segregants from different translocations.

T(1;Y), T(Y;2) and T(Y;3) stocks for this “segmental aneuploidy” approach are available from Kyoto Drosophila Genomics and Genetic Resources for making X, second and third chromosome deletions and duplications. This approach can also be used with T(1;Y) chromosomes with breakpoints in X heterochromatin to create deletions and duplications of Y chromosome segments (see Gatti and Pimpinelli (1983)). It has proved to be the most effective way to create deletions of Y-linked male fertility genes, since conventional deletions on the Y chromosome are unstable. Translocation segregants from the following T(1;Y) stocks can be combined to make deletions.

Note that several T(Y;2) and T(Y;3) chromosomes are maintained because their breakpoints disrupt specific Y-linked male fertility genes (see Translocations that cause mutations above). These chromosomes are not maintained for creating deletions.

T(1;Y)N12 and T(1;Y)R12 have one breakpoint in X centric heterochromatin and one breakpoint near the tip of a special Y chromosome that has y[+] marking the tip of the short arm and B[S] marking the tip of the long arm.

The B[S]-marked translocation segregant has all the Y-linked male fertility genes and all the X-linked euchromatic genes. This makes it an attached-XY [C(1;Y)] chromosome. The y[+]-marked translocation segregant is a tiny, dispensable chromosome.

The large translocation segregants from T(1;Y)N12 and T(1;Y)R12 are the only simple C(1;Y) chromosomes in the Bloomington collection with B[S] marking the Y tip. C(1;Y)N12, the attached-XY segregant from T(1;Y)N12, was used in constructing Dp(1;Y)BSC chromosomes. As far as we know, the attached-XY derived from T(1;Y)R12 has never been used for further chromosome constructions.

T(1;4)sc[H] is a reciprocal translocation with breakpoints near the tips of the X and fourth chromosomes.

T(Y;3)L129 is a reciprocal translocation with breakpoints in a y[+]-marked Y chromosome and at 100C on 3R.

T(1;2)sc[S2] is a reciprocal translocation between the tips of the X chromosome and 2R. It marks the tip of 2R with y[+]. This is useful for detecting mitotic clones formed by somatic recombination events within 2R.

Unlike similar duplications of y[+] onto the tips of other chromosome arms, both chromosomes of the reciprocal translocation T(1;2)sc[S2] must be present for flies to survive. This complicates clonal analysis crosses and we suggest you review previous studies that have used it before undertaking experiments.

We have a few stocks where a translocation is present, but it has nothing to do with the primary component of the stock and serves no particular purpose.