Required for embryonic development and gonadogenesis. Also, functions redundantly with the transcriptional repressor lin-35 to regulate somatic gonad development. ATP + H2O = ADP + H(+) + phosphate Expressed in most cells during embryonic development (PubMed:15328017, PubMed:15649460). First expressed at around the 100-200 cell stage of embryogenesis (PubMed:15328017, PubMed:15649460). Expression was absent or reduced in intestinal cell lineages during this time. Highly expressed in neuronal cells of the head, ventral nerve cord and tail during the late stages of embryogenesis (PubMed:15328017). Highly expressed in all dividing cells after hatching (PubMed:15649460). Highly expressed in the P lineage during the L1 stage of larval development (PubMed:15649460). During larval development, mainly expressed in the neurons, but there is also high expression in the junctional cells of the spermatheca and uterus, and weak expression in cells of the somatic gonad including the distal tip cells (PubMed:15328017). Temperature-sensitive with 38% embryonic lethality at 25 degrees Celsius (PubMed:15649460). A large proportion of surviving animals are sterile. Surviving animals also have gonad developmental defects such as defective gonadal arm growth and as a result irregular distal tip cell migration, and 24% of animals had a protruding vulva phenotype (PubMed:15649460). Reduced brood size (PubMed:15328017). Double knockout with lin-35 results in 43% embryonic lethality (PubMed:15328017). Surviving animals develop slowly, are small, sterile and display male and female gonad developmental defects characterized by shorter gonadal arms, fewer germ cells, an everted vulva phenotype, and failed formation of sheath and spermathecal cells (PubMed:15328017). RNAi-mediated knockdown of lin-35 or hpl-2 results in larval arrest at 25 degrees Celsius in an xpn-1 mutant background (PubMed:15649460). Belongs to the SNF2/RAD54 helicase family.