Translational repressor that inhibits protein synthesis (PubMed:9508766, PubMed:26492166). Represses the translation of mRNAs such as fib-1, probably by being recruited by RNA-binding protein nos-2 and the Pumilio proteins puf-5, puf-8 and puf-9 to the consensus core PUF binding motif in the 3'-UTR of fib-1 mRNA (PubMed:26492166). Negatively regulates ribosomal RNA (rRNA) synthesis, ribosomal protein synthesis and nucleolus size (PubMed:9508766, PubMed:8582642, PubMed:22768349, PubMed:26492166, PubMed:28853436). Its role in the negative regulation of nucleolus size is most likely through its negative regulation of the translation of proteins such as the rRNA 2'-O-methyltransferase fib-1, and dao-5 (PubMed:26492166, PubMed:28853436). Might act directly as a transcription factor to inhibit RNA polymerase I (rRNA) and III (5S RNA) transcription (PubMed:9508766). Plays a role in embryonic development, and in particular, is involved in regulating the localization of proteins, such as par-2, that are required for embryonic cell polarity (PubMed:18652816). Plays a role in the regulation of lifespan, and the response to nutrient availability (PubMed:28853436). Present in cells in which nucleoli are absent, and absent from large cells in which nucleoli are prominent (PubMed:9508766). Highly expressed in the gonads (PubMed:26492166). Expressed in embryos (PubMed:9508766, PubMed:18652816, PubMed:26492166). Abundant in early embryos, but displays a progressive decline throughout the four larval stages, and is subsequently up-regulated in the adult (PubMed:9508766, PubMed:26492166). Negatively regulated by the let-7 microRNA. No visible change in viability, fertility, development, body morphology or movement (PubMed:8582642). However, animals are approximately 9% larger after hatching than wild-type counterparts (PubMed:9508766). Mild defects in early embryonic cell development (PubMed:18652816). No visible change in lifespan, however in contrast to wild-type, longevity is significantly reduced in response to dietary restriction (PubMed:28853436). Furthermore, it suppresses the increased longevity and reduced nucleoli size of eat-2 (ad465), glp-1 (e2141), isp-1 (qm150), and daf-2 RNAi and let-363 RNAi longevity mutant models (PubMed:28853436). Most cells contain enlarged nucleoli, with the exception being intestinal and germline nucleoli, which are not markedly larger (PubMed:9508766, PubMed:8582642, PubMed:26492166, PubMed:28853436). In contrast to wild-type, the oocyte which is immediately adjacent to the spermatheca contains a nucleolus (PubMed:26492166). Nucleoli have an increased capacity for protein synthesis, specifically RNA polymerase I and III transcription (PubMed:9508766). Defective ribosomal biogenesis with increased expression of rRNAs such as 26S rRNAs, and ribosomal proteins including rps-6 and rsp-15 (PubMed:26492166, PubMed:28853436). Knockout with fib-1 RNAi suppresses the enlarged nucleolus phenotype in embryos and suppresses the increased 26S ribosomal RNA (rRNA) expression in the single ncl-1 mutant (PubMed:26492166). Double knockout with par-2 mutant (it5ts) suppresses the lethality phenotype, embryonic polarity defects of the par-2 mutant (it5ts) at 25 degrees Celsius (PubMed:18652816).