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27 grudnia 2023

We provide evidence that miRNA miR-71 is not required for the animals’ entry into L1 diapause, but plays a critical role in long-term survival by repressing the expression of insulin receptor/PI3K pathway genes and genes acting downstream or in parallel to the pathway. Full device encrypted backups to iTunes will back up both the account listings and private key pairs, but can only be restored on the SAME phone that created the backup. If you enabled third-party account backup, you can recover your accounts on your iOS or Android device. If your organization hasn’t enabled self-service device management, contact your IT Help Desk or Duo service administrator for assistance reactivating the account. If you can’t open Duo Mobile on your old device, for example, if your phone was lost or damaged, contact your Duo administrator to discuss your account recovery options. You must have access to Duo Mobile on your old Android device in order to use Instant Restore to restore your Duo-protected account backup to your new device.

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It is also worth mentioning that multiple components of the InsR pathway, including age-1, pdk-1, akt-2, and daf-16, are predicted to be targets of the let-7 family miRNAs. Our data provide the experimental evidence that two components of the InsR pathway are likely direct targets of miR-71 in its role in a specific physiological process, L1 diapause (see a model in Fig. S5). Components of the InsR pathway, including age-1, have recently been predicted to be targets of miR-71 in its role in aging (14). These results compelled us to examine specific interactions between individual miRNAs and their targets to gain mechanistic insights. This result suggests that miR-71 likely functions upstream of, or in parallel to, HBL-1 in regulating VPC timing.

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Duo Mobile cannot recover access to those accounts without a backup. Be sure to enable third-party account backup and restore if you use Duo Mobile to generate passcodes for logging into applications like Instagram, Facebook, Snapchat, or other web services. To compare the survival rates between strains, we simulated the survival rate of each genotype to 100 arbitrary “individual worms” and performed the log-rank test in Graphpad Prism 4. This result suggests that the high expression of miR-71 during L1 diapause is induced or maintained by other signaling pathways. We asked whether the expression of miR-71 was regulated by DAF-16, which is required during L1 diapause for long-term survival (2).
MT12993 mir-71(n4115) worms were outcrossed with N2 for four generations before any test except the initial screen. A recent study showed that the expression of miR-71 was significantly increased relative to other miRNAs in starved L1 worms (15). However, miR-71 does not appear to regulate all postembryonic development during L1 diapause recovery. Unlike classical heterochronic miRNAs such as lin-4 and let-7, the role of miR-71 in vulval cell division is essential in animals recovering from starvation-induced L1 diapause, but not in animals hatched on plates with food. As pointed out above, multiple miRNAs in addition to miR-71 and the let-7 family miRNAs have roles in L1 diapause, and they may regulate the expression of many diverse targets that may include, but are not limited to, factors involved in UNC-31–InsR-signaling activities.
We thus asked whether miR-71 was required for the reinitiation of developmental programs during the recovery phase after L1 starvation. These results suggest that miR-71 regulates the expression of unc-31 and age-1 through their 3′UTRs. Note that there are extra GFP-positive cells (red arrows) in mir-71(lf) mutants.

Furthermore, the observed derepression of individual genes by mir-71(lf) seemed too weak to account for the phenotype, consistent with the idea that a prominent phenotype of an miRNA mutation is caused by the collective effect of changing expression in many genes, an important property of miRNA-mediated gene regulation. (F) Fluorescence and DIC images showing that an hbl-1 3′UTR reporter was repressed in mir-71(+) worms and slightly derepressed in mir-71(lf) mutants. (E) DIC images showing that hbl-1(RNAi) caused precocious VPC divisions in late L2/early L3 in both wild-type and mir-71(lf) worms recovered from 4 d of L1 starvation. Note that the daf-16(lf) worms recovering from 3 d of L1 starvation displayed a ∼12-h delay in overall development and that the mir-71(lf); daf-16(lf) double mutants displayed an ∼24-h delay. (C) Bar graph showing that the delayed VPC timing defects of mir-71(lf) worms was suppressed by an unc-31(lf) mutation and partially suppressed by an age-1(rf) mutation.

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In worms that recovered from 4 d of L1 starvation, we also found that a significant portion of the mir-71(lf) mutants displayed egg-laying defects and overproliferating or precociously reflexed gonads. We further examined worms recovering from 4 d of L1 starvation and found that around 90% of the mir-71(lf) mutants displayed retarded vulval precursor cell (VPC) division, compared with less than 5% in wild type (Fig. 4A). We found that the 3′UTRs of several genes of the InsR pathway, including unc-31, age-1, pdk-1, akt-2, and sgk-1, contain predicted miR-71 targeting sites (as predicted by TargetScan and mirWIP). (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 poor survival rate of daf-16(mu86)(lf) was further decreased by mir-71(lf) (Fig. 2C), consistent with the notion that a portion of miR-71 activities regulate genes that act in parallel to UNC-31–mediated InsR/PI3K signaling for long-term survival during L1 diapause.

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L1 starvation assay was adapted from a previously described protocol (3). Worms strains were grown and maintained at 20 °C as described (29). This result is consistent with the observation that miR-71 is specifically required for the starvation-induced stress response (Fig. S5). For example, we observed a robust retarded mutant phenotype in the vulval lineage but did not see obvious defects in seam cell differentiation or alae formation. It seems plausible that miRNAs that control developmental timing are also involved in regulating the metabolic rate through repressing the InsR pathway activity.
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). Unlike dauer diapause, L1 diapause is not accompanied by life cycle changes and has not been shown to require certain signaling pathways that control the formation of dauer diapause such as TGF-β signaling (daf-1, daf-7) and nuclear hormone receptor (daf-12) (2, 3). The coordinated entrance into developmental arrest, long-term survival, and the reinitiation of development upon food availability are important biological processes to investigate. Different organisms have developed versatile growth arrest strategies to overcome starvation-induced metabolic and developmental problems.
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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. Numerous animal species across multiple phyla enter developmental arrest for long-term survival in unfavorable environments and resume development upon stress removal. Such lagged trait recovery, combined with rapid invasive recovery, suggests potential for longer-term shifts in grassland composition and function.