Thereof, can I use Nikon lens on Sony?
You can now use Nikon lenses on all Sony bodies. With the number of people making the shift from more traditional DSLRs to Sony mirrorless systems, adapters are often a way of life. Like the Fotodiox Fusion adapter for Canon, the new Nikon adapter transfers aperture control to the camera with G type lenses.
Also, what cameras can use Nikon lenses? Depends upon the camera. You can use most older Nikon lenses on Canon bodies, for instance, with the right adapter. Most of the mirrorless cameras (Olympus and Panasonic m4/3, Samsung NX, and Sony E/FE) can use Nikon lenses with the right adapter, as well.
Considering this, can Sony a7 use Nikon lenses?
Manual Focus Nikon G/F Lens AdaptersMetabones Nikon F to Sony E-Mount Adapter II ($90 at Amazon | B&H) is a great choice to mount them on A7/A7R. You can use Nikon F lenses on Nikon G adapters – but Nikon F adapters can't control the aperture of Nikon G lenses.
Can I use Nikon DSLR lens on mirrorless camera?
You can use DSLR lenses on a mirrorless camera provided the mount on the camera and the lens are the same, or you can get a mount adapter to suit. There are several different adapters to allow Nikon F mount lenses to be used on Sony cameras with E-mount. Some adapters are quite expensive.