Introduction

The successful extraction or amplification of DNA from fossils at least thousands of years old,[1-9] from preserved tissues at human burial sites,[10-16] and from museum specimens,[17-25] clearly demonstrated the potential for the storage of DNA. Spontaneous decomposition of DNA primarily results from depurination/p-elimination[26] and free radical oxidation pathways.[27] In solution DNA will spontaneously degrade to short fragments over a time period of several thousand years at moderate temperatures.1-26-1 Numerous methods have been developed for the storage of DNA or for tissue for the extraction of DNA; however, relatively few studies have been published that examine or compare the ability of these methods to prevent or reduce DNA degradation, especially over periods of times greater than a few months.

DNA chain undergoes cleavage by a p-elimination process within a few days.[34] The pH of the storage solution is expected to have a large effect on DNA stability. DNA bases and deoxyribose sugars are also susceptible to degradation by free radical oxidation.[27] Use of specific chelators, such as EDTA, has been found to be extremely effective at reducing free radical oxidation for at least 1 year of DNA stored at room temperature.[35]

Degradation of DNA in a sample may also result from the action of endogenous enzymes, endo- and exo-nucle-ases, that cleave DNA strands.[28] Temperature, pH, and salt concentration are known to influence enzymatic activity.[36] Nucleases are divalent cation-dependent enzymes and their activity is much reduced at high concentrations of EDTA or diaminocyclohexanetetraace-tate (CDTA).

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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