Figure 2.

Reduced sirtuin levels are neuroprotective: A 50% reduction of Sir2 (i.e. heterozygous null) leads to (A) greater survival to adulthood and (B) an increased number of photoreceptor neurons of Httex1p Q93-expressing flies; (C) heterozygous loss of Sirt2 also reduces photoreceptor neuron survival; (D) sirtinol, (E) nicotinamide and (F) niacin administration result in reduced neuronal death; (G) pseudopupil images of a normal eye and 7-day-old Httex1p Q93 flies is shown; niacin reduces the rhabdomere loss in Htt flies.