Poly tract composition

Low-complexity sequence. The phrase low-complexity sequence refers to stretches of nucleotide or protein sequence that are repetitive or simple in composition (11). Extreme examples include runs of As in a nucleotide sequence such as the poly-A tails of eukaryotic mRNAs, or the poly-proline tracts found in some... 

The poly(A) tracts contained in these presumptive mRNA molecules are generally 150-200 nucleotides in length and have a base composition of greater than 85 adenine. Evidence has also been presented for the occurrence of an adenylate-rich sequence in 10 S rabbit reticulocyte globin mRNA (Lim and Canellakis, 1970). RNA transcribed from vaccinia virus DNA has also been shown to contain a large poly( A) sequence localized at the 3 end of the molecule (Kates, 1970). Poly (A) tracts... 

Ducts and Canals.—Prostheses implanted in the urinary tract have been discussed with reference to the use or potential use of poly(ethylene terephthalate), silicone rubber, polytetrafluoroethylene, poly(vinyl chloride) and nylon. Experimental work on uretral and urethral replacement involves, principally, composites of poly(ethylene terephthalate) and silicone rubber. A new silicone rubber prosthetic bladder is described and a preliminary report of an implantable lung in J. H. Dumbleton, Wear, 1978, 49, 297. 

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