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: Immunoperoxidase brightfield - and laser - scanning confocal fluorescence microscopy demonstrated increased targeting of alpha - ENaC , beta - ENaC , and gamma - ENaC subunits to the apical plasma membrane in the distal convoluted tubule ( DCT2 ) , connecting tubule , and cortical and medullary collecting duct segments .
### Output Text:
Immunoperoxidase brightfield - and laser - scanning confocal fluorescence microscopy demonstrated increased targeting of alpha - ENaC , beta - ENaC , and gamma - ENaC subunits to the apical plasma membrane in the distal convoluted tubule ( DCT2 ) , connecting tubule , and cortical and medullary collecting duct segments . 