In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Dup 753 prevents the development of puromycin aminonucleoside - induced nephrosis .
### Output Text:
<span class="chemical">Dup 753</span> prevents the development of <span class="chemical">puromycin aminonucleoside</span> - induced nephrosis . 