what is chromosome U in the fly?

[cnidacxb]

hello, the guys passing this page.
I hope you can answer the quesion for me and thanks a lot.

I sequenced a DNA fragment and blasted it. the results showed that it located in the Chromosome U in fly. but as i know that there are only chromosome X/Y III III IV in drosophila melanogaster.I don't know what this refers to. and is there some relations to other known chromosomes?
By the way, the DNA is amplified from lavae genome. Does it belong to salivary polytene chromosome?

thanks again!

[Josh Goodman]

Hello,

Arm U in Drosophila melanogaster is a random concatenation of pieces of the genome which could not be placed on any of the existing chromosomes. It doesn't mean that they don't exist in any of the chromosomes, just that the current assembly wasn't able to place them anywhere.

Josh

[LTY83]

Very interesting.