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: Whatever was the dose , the central administration of U - II had no effect on body temperature , nociception , apomorphine - induced penile erection and climbing behavior , and stress - induced plasma corticosterone level .
### Output Text:
Whatever was the dose , the central administration of <span class="chemical">U - II</span> had no effect on body temperature , nociception , <span class="chemical">apomorphine</span> - induced penile erection and climbing behavior , and stress - induced plasma <span class="chemical">corticosterone</span> level . 