Tiny, 45 base long RNA can make copies of itself

Self-copying RNAs may have been a key stop along the pathway to life.

Complex water networks visualized by cryogenic electron microscopy of RNA - Nature

Using cryogenic electron microscopy and a modelling approach, complex water networks in a ribozyme are visualized.

A recombinase-activated ribozyme to knock down endogenous gene expression in zebrafish

Author summary Understanding mRNA and protein function requires tools to module gene expression. Current tools in vertebrates include site-directed recombinases and endonucleases, which display variable efficiency depending on the genomic context. Here, we introduce a complementary tool to knock down gene expression in zebrafish, one based on the T3H48 self-cleaving ribozyme. We first show that the T3H48 ribozyme can reduce the expression of a reporter transgene, as well as that of an endogenous gene. Using a base-editing strategy to inactivate the ribozyme, we show that this knock down is specific and reversible. We then created a Flippase- and Cre-activatable T3H48 ribozyme called RiboFlip. We find that the induction of RiboFlip recapitulates the mutant phenotype when inserted in the albino gene. Moreover, we show that a Cre- and Dre-controllable Gal4/UAS reporter in the RiboFlip cassette can label knocked-down cells independently of the expression of the target gene. Altogether, these data show that the RiboFlip can serve as a flexible knockdown tool, thereby complementing existing strategies to control gene expression.

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Modeling the origins of life: New evidence for an 'RNA World'

Charles Darwin described evolution as "descent with modification." Genetic information in the form of DNA sequences is copied and passed down from one generation to the next. But this process must also be somewhat flexible, allowing slight variations of genes to arise over time and introduce new traits into the population.