Alternative splicing and adenosine to inosine (A to I) RNA-editing are major factors leading to co- and post-transcriptional modification of genetic information. Both, A to I editing and splicing occur in the nucleus. As editing sites are frequently defined by exon–intron basepairing, mRNA splicing efficiency should affect editing levels. Moreover, splicing rates affect nuclear retention and will therefore also influence the exposure of pre-mRNAs to the editing-competent nuclear environment. Here, we systematically test the influence of splice rates on RNA-editing using reporter genes but also endogenous substrates. We demonstrate for the first time that the extent of editing is controlled by splicing kinetics when editing is guided by intronic elements. In contrast, editing sites that are exclusively defined by exonic structures are almost unaffected by the splicing efficiency of nearby introns. In addition, we show that editing levels in pre- and mature mRNAs do not match. This phenomenon can in part be explained by the editing state of an RNA influencing its splicing rate but also by the binding of the editing enzyme ADAR that interferes with splicing.

With the European Green Deal, the importance of recycled products and materials has increased. Specifically, for PET bottles, a high content of recycled material (rPET) is demanded by the industry and consumers. This study was carried out in a lab environment replicating real-life industrial processes, to investigate the possible impacts on rPET quality over eleven recycling loops, aiming to use high amounts of rPET repetitively. A cycle included extrusion, solid state polycondensation (SSP), a second extrusion to simulate bottle production, hot wash and a drying step. 75% rPET and 25% virgin PET were extruded in eleven cycles to simulate a recycling and production process. Samples underwent chemical, physical and biological analysis. The quality of the rPET material was not adversely affected. Parameters such as coloring, intrinsic viscosity, concentration of critical chemicals and presence of mutagenic contaminants could be positively assessed. The quality of the produced material was likely influenced by the input material’s high standard. A closed loop PET bottle recycling process using an rPET content of up to 75% was possible when following the proposed process, indicating that this level of recycled content can be maintained indefinitely without compromising quality.

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