piwi
...that RNA-binding piwi proteins are required for the formation of sperm in many animals, including mammals?
...that <a href="./RNA" id="mwBxQ" rel="mw:WikiLink" title="RNA">RNA</a>-binding <b id="mwBxU"><a href="./Piwi" id="mwBxY" rel="mw:WikiLink" title="Piwi">piwi</a></b> proteins are required for the formation of <a href="./Sperm" id="mwBxc" rel="mw:WikiLink" title="Sperm">sperm</a> in many animals, including <a href="./Mammal" id="mwBxg" rel="mw:WikiLink" title="Mammal">mammals</a>?