Abstract
The objective of this research is to determine the effect of heterochromatin on genes found within heterochromatic regions of standard chromosomes of Drosophila melanogaster. | The system used in this investigation involves the light (lt: 2-55.0) allelic gene pair, an eye color locus located in the left arm of the second chromosome. The phenotype is an eye that is yellowish-pink in color, lighter at higher temperatures, darker at low (Lindsley and Grell 1968). | The light system exhibits a maternal effect, that is, larval Malpighian tubules (MPT) are colorless in light offspring if their mothers are lt/lt, but do exhibit some color if the mother is lt+/lt (Beadle 1937). The yellow pigment found in the MPT is primarily riboflavin (Nickla 1972a) which can be measured quantitatively by using fluorometric procedures. The amount of riboflavin in the MPT is therefore, a measure of the activity of the lt+ allele.