piRNAs silence transposons to safeguard genome integrity in animals. However, the functions of the many piRNAs that do not map to transposons remain unknown. Here we showed that piRNA targeting in C. elegans can tolerate a few mismatches but prefer perfect pairing at the seed region. The broad targeting capacity of piRNAs underlies the germline silencing of transgenes in C. elegans. Transgenes engineered to avoid piRNA recognition are stably expressed. Interestingly, many endogenous germline-expressed genes also contain predicted piRNA targeting sites, and periodic An/Tn clusters (PATCs) are an intrinsic signal that provides resistance to piRNA silencing. Together, our study revealed the piRNA targeting rules and highlights a unique strategy that C. elegans uses to distinguish endogenous from foreign nucleic acids.

PIWI-interacting RNAs (piRNAs) are a class of small noncoding RNAs that guard animal genomes against mutation by silencing transposons. In addition, recent studies have reported that piRNAs silence various endogenous genes. Tens of thousands of distinct piRNAs made in animals do not pair well to transposons and currently the functions and targets of piRNAs are largely unexplored. piRTarBase provides a user-friendly interface to access both predicted and experimentally identified piRNA targeting sites in Caenorhabditis elegans. The user can input genes of interest and retrieve a list of piRNA targeting sites on the input genes. Alternatively, the user can input a piRNA and retrieve a list of its mRNA targets. Additionally, piRTarBase integrates published mRNA and small RNA sequencing data, which will help users identify biologically relevant targeting events. Importantly, our analyses suggest that the piRNA sites found by both predictive and experimental approaches are more likely to exhibit silencing effects on their targets than each method alone. Taken together, piRTarBase offers an integrative platform that will help users to identify functional piRNA target sites by evaluating various information. piRTarBase is freely available for academic use at http://cosbi6.ee.ncku.edu.tw/piRTarBase/.

AbstractpirScan is a web-based tool for identifying C. elegans piRNA-targeting sites within a given mRNA or spliced DNA sequence. The purpose of our tool is to allow C. elegans researchers to predict piRNA targeting sites and to avoid the persistent germline silencing of transgenes that has rendered many constructs unusable. pirScan fulfills this purpose by first enumerating the predicted piRNA-targeting sites present in an input sequence. This prediction can be exported in a tabular or graphical format. Subsequently, pirScan suggests silent mutations that can be introduced to the input sequence that would allow the modified transgene to avoid piRNA targeting. The user can customize the piRNA targeting stringency and the silent mutations that he/she wants to introduce into the sequence. The modified sequences can be re-submitted to be certain that any previously present piRNA-targeting sites are now absent and no new piRNA-targeting sites are accidentally generated. This revised sequence can finally be downloaded as a text file and/or visualized in a graphical format. pirScan is freely available for academic use at http://cosbi4.ee.ncku.edu.tw/pirScan/.

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Self-healing gelatin resistive random access memory (RRAM), namely, SHG RRAM, is utilized by incorporating the reversible imine bond as self-healing points into the gelatin. With the reformation of the dynamic imine bonds, the damaged SHG RRAM can repeatedly restore its memory properties after healing at 60 °C. Compared with the pristine SHG RRAM, the SHG RRAM after the healing process exhibits a higher ON/OFF ratio of over 10 5 . This interesting phenomenon could be attributed to the bending and heating process induced C−C sp 3 bonds, which consequently decrease the HRS current. In addition, the CAFM images can show that the filament paths occurred at the healed crack edge, leading to usefulness of the cracks in the formation of filament paths. These results repudiated the concept that cracks due to bending can reduce the performance of electronics. Moreover, the SHG RRAM after the healing process shows reproducible resistive switching, acceptable electrical uniformity, and stable retention characteristics. The self-healing gelatin material could provide a potential opportunity for the future development of biopolymers used in smart electronics applications.