Salivary Gland Type Chromosomes in Mosquitoes

Abstract

Best prepns. are from Malpighian tubules of imago, pupa or 4th-instar larva though also obtainable from salivary glands, etc. Salivary chromosomes of adult are normal somatic. Cells are fixed 1 min. in acetic alcohol then stained 1 hr. in 1% orcein in 45% acetic acid and smeared since the standard aceto-carmine technique proved inadequate. In both Culex pipiens and Aedes aegypti n = 3, and a single chromocenter is lacking. In Ae. aegypti the nucleolus is invisible in later stages and the chromosomes show "weak spots" where the bands fail to stain. In young larvae regular banding is not present but the nucleic acid is concentrated in spherical masses separated by achromatic regions.