{HEAD ~ The SIR2 gene family} of proteins is conserved from {TAIL ~ bacteria} to man  
is conserved from
{ HEAD ~ The SIR2 gene family } of proteins is conserved from { TAIL ~ bacteria } to man
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH