Endogenous retroviruses synthesize heterologous chimeric RNAs to reinforce human early embryo development - Science | AAAS

Chimeric RNAs (chRNAs) expand transcriptomic and proteomic diversity by joining sequences from distinct genomic loci, yet their physiological functions remain poorly understood. In a recent paper published in Nature, Venezia et al. show that inflammation induces CTCF-dependent chRNA formation in mammalian immune cells and that a Gsdmd-Tmem106a chRNA encodes a functional fusion protein that modulates pyroptosis and the balance between antibacterial defense and inflammatory pathology. The mammalian genome contains a surprisingly limited number of protein-coding genes relative to the complexity of mammalian organisms. Alternative splicing, RNA editing, non-canonical translation and post-translational modification expand the functional output of this finite genome. Chimeric RNAs (chRNAs), in which sequences from distinct genomic loci are joined within a single transcript, may represent another layer of this regulatory complexity.1,2,3 Historically, chimeric transcripts have been closely associated with cancer-associated chromosomal rearrangements.

A massive asteroid slammed into the North Sea roughly 43 to 46 million years ago, triggering a tsunami more than 100 meters (330 feet) high. Now, after more than two decades of scientific disagreement, researchers have uncovered compelling evidence confirming the ancient collision. The impact created what is now known as the Silverpit Crater, a massive structure buried deep beneath the seafloor. Although scientists first discovered it in 2002, its origins remained fiercely debated, with some researchers arguing that geological processes, rather than an object from space, were responsible.

As the U. S. and Europe increasingly shift away from animal research, organoids have been touted as a promising alternative method for studying the brain. The field has made significant progress since human brain organoids debuted in 2013. Researchers can now coax these clusters, fashioned from stem cells, to integrate a variety of cell types, including microglia, astrocytes and interneurons. They can even fuse brain-region-specific organoids into structures called assembloids that closely resemble circuits within the brain.