(H and I) Fluorescence images (H) and statistical data (I) showing that the M cell diveded in fed animals but remained undivided in 4-, 7-, or 11-d–starved L1 wild-type and mir-71(lf) worms. (E) Fluorescence and DIC images showing that the unc-31 3′UTR reporter was repressed in mir-71(+)worms (2/2 transgenic lines) but not in mir-71(lf) worms (4/4 transgenic lines). We found that the reduced survival rate of ain-1 was suppressed by either reduction of age-1 function or loss of unc-31 function (Fig. 1 B and C), suggesting that a significant portion of the overall miRNA functions in L1 diapause is upstream of, or in parallel to, the InsR pathway. Previous studies indicate that the InsR pathway plays a dominant role in regulating L1 starvation survival and that reducing the activity of the insulin receptor daf-2, the PI3Kinase age-1, or the upstream regulator unc-31 results in increased L1 starvation survival rate (2, 3). The two ain-1 loss-of-function alleles displayed significant reductions in L1 starvation survival rate. We found that ain-1 but not ain-2 mutants displayed a significant reduction in L1 starvation survival rate compared with that of wild type (Fig. 1 A and D).
On play, trauma, and wellbeing
Upon entering L1 diapause, RNA polymerase II quickly accumulates and pauses at promoter regions, and this accumulation was speculated to stop transcription and facilitate the immediate reinitiation of gene expression when food becomes available (2). Previous studies showed that the release of postdocking calcium-regulated dense-core vesicles, the insulin receptor (InsR) pathway, the AMPK pathway, and protein chaperones are required for the long-term survival of starved L1 worms (2–4). However, when newly hatched L1 worms encounter an environment with no food, developmental programs arrest and the worm enters L1 diapause. The presented results indicate that interactions between multiple miRNAs and likely a large number of their mRNA targets in multiple pathways regulate the response to starvation-induced L1 diapause. And we need to take seriously that, just as people’s literary diet matters, so does their ludic diet. In fact I still have a ton to say, about play anxiety and devaluation of play, which I’ll have to put into separate posts over the next few days.
