low Tm primer PCR

[steven heckt]

	You should not have to lower the extension temperature. In
	working with much lower Tm primers, you can consider the
	extension rate of your pol, which is slow but still going
	at lower temperatures, and sa you get extension the Tm will
	increase. So- you may consider using ramps; ie, ramp down to
	annealing slowly to allow the best matches and ramp up to
	your extension temp to allow the interplay of annealing and
	extension to work itself out.