Actually, the gather node is not useful today.  It did a very clumsy job of what IDL now accomplishes in general.  Do not use gather in P9.  Just turn on IDL. 

Gather was fun, but very rudimentary in terms of developing indirect lighting.

There doesn't need to be any new extensions for "bioluminescence" (quotes not to be snarky, but to because I'm assuming this is a very specific effect and not something more precisely modeled after true bioluminescence).   For the edge glow effect , just make an ambient material that takes an Edge Blend.  You can make it with a black inner color and a white outer color and feed it into Ambient Value to just work with one ambient color, or you can set up two different colors in the Edge Blend and feed that into Ambient Color.

That's the simple approach.  If you want to get more creative with your glow, you can do all kinds of things with other nodes.  That's the wonderful thing about a node architecture.  You can always build your way to advanced materials.