A nematode having {HEAD ~ null mutations} in hop 1 and {TAIL ~ sel} 12, said nematode having a combined maternal effect embryonic lethality and egg laying defective phenotype, at least one of said mutations being introduced by artifice, wherein said nematode is a C. elegans nematode 
A nematode having { HEAD ~ null mutations } in hop 1 and { TAIL ~ sel } 12 , said nematode having a combined maternal effect embryonic lethality and egg laying defective phenotype , at least one of said mutations being introduced by artifice , wherein said nematode is a C. elegans nematode
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH