Sentence:  While Shelly was away from the lab, Rene decided that it would be easier to divide the lengthy segment into smaller pieces, or <WSD>subclones</WSD>, and to insert each fraction into plasmids, little circles of DNA and protein. 
Meaning of the word marked with <WSD> tags:  A partial segment of DNA, cloven from a previously-cloned segment, which is then cloned into another vector