ABSTRACT
In principle it is most economical to sequence large DNA fragments consecutively ('primer walking'), provided there is an immediate supply of sequencing primers. To solve the problem of primer supply we previously suggested generating a bank of short oligonucleotide primers ('shortmers'). In every sequencing reaction shortmers would have to be selected from this bank that are suitable to hybridize adjacently on the sequencing template. After their ligation the shortmers would form a long, and hence more specific, primer in the subsequent sequencing reaction. In the present study a computer simulation of large sequencing projects revealed a reduced set of approximately 12,000 selected octanucleotides (out of all 65,536) retaining maximum priming flexibility and minimum redundant information on the simulated sequence analyses. Establishing routine protocols for nucleic acid sequencing following the shortmer approach will abolish the tightest bottleneck of the consecutive sequencing route (primer supply) and hence may render this general scheme more attractive than the shotgun sequencing scheme. A twofold (or more) speed-up of genome sequencing projects by the shortmer approach may be assumed.
Subject(s)
Computer Simulation , DNA/analysis , Models, Genetic , Algorithms , Base Sequence , DNA PrimersABSTRACT
The mercury contents in samples of flour, sugar, nonfat dry milk, potatoes, hamburger, chicken breast, shrimp, liver, eggs, and whole milk were determined by neutron activation analysis. The mercury was separated by anion exchange chromatography and precipitated as the sulfide. The mercury concentrations for all these foods were below 50 parts per billion.
