Period 6 element heavy metal, lead is a neurotoxin that accumulates both in soft tissues and the bones. Lead poisoning has been documented from ancient Rome, ancient Greece, and ancient China. Bismuth is a chemical element with symbol Bi and atomic number 83. Bismuth, a trivalent other metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery white color when newly made, but often seen in air with a pink tinge owing to the surface
C-rich stability element been mapped to a pyrimidine-rich segment of its 3' UTR. This region confers stability by directing the assembly of a specific alpha ribonucleoprotein complex at this site. Subsequently Holcik and Liebhaber identified three other highly stable eukaryotic mRNAs that assemble the alpha globin protein complex at homologous pyrimidine-rich regions within their 3'UTRs (rabbit lipoxygenase, rat tyrosine hydroxylase, and human alpha(I)-collagen). There is some debate as to the number and identity of trans-acting factors recruited to the C-rich element. However the alpha globin poly(C)-binding protein (alphaCP) is agreed to be the core constituent of what is known as the alpha complex.