Temperature Control

Room temperature fluctuations cause problems with proper sizing of STR alleles when using the ABI 310. Electrophoretic separations of STR samples are performed at a temperature of 60°C in order to minimize the formation of DNA secondary structure or intrastrand hybrid structures that impact the DNA separation (Wenz et al. 1998). DNA sizing is less precise at a lower temperature because of the DNA secondary structure that forms when the strands are not kept fully denatured. Variation in the run temperature will result in relative migration differences between the internal sizing standard DNA fragments and the STR alleles being measured and thus a change in the calculated size of the STR alleles. Because samples are run in a sequential fashion on a capillary system, maintaining a high degree of precision is essential in order to compare the allele sizes in an allelic ladder to those in the samples being analyzed (Lazaruk et al. 1998).

The ABI 310 has a heated plate that is used to raise and maintain the temperature of the capillary. However, several centimeters of the capillary at both the inlet and outlet ends are exposed to the air and not directly in contact with the temperature-controlled plate. Maintaining the room temperature to a precision of less than ± 1°C will improve the precision of DNA separations on the ABI 310. Newer CE instruments, such as the 16-capillary ABI 3100 system, have improved temperature control that mitigates these thermal fluctuation problems.

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Stammering Its Cause and Its Cure

Stammering Its Cause and Its Cure

This book discusses the futility of curing stammering by common means. It traces various attempts at curing stammering in the past and how wasteful these attempt were, until he discovered a simple program to cure it. The book presents the life of Benjamin Nathaniel Bogue and his struggles with the handicap. Bogue devotes a great deal of text to explain the handicap of stammering, its effects on the body and psychology of the sufferer, and its cure.

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