preferred_name: (6Z,9Z,12Z,15Z)-octadecatetraenoyl-containing glycerolipid + 2 Fe(II)-[cytochrome b5] + O2 + 2 H(+) = a (9Z,12Z,15Z)-octadeca-9,12,15-trien-6-ynoyl-containing glycerolipid + 2 Fe(III)-[cytochrome b5] + 2 H2O