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: Such contralateral rotation may result from either degeneration - induced breakdown of the DA pool , or lesion - induced increase of DA turnover in the spared neurons .
### Output Text:
Such contralateral rotation may result from either degeneration - induced breakdown of the DA pool , or lesion - induced increase of DA turnover in the spared neurons . 