Erik G. Ellgaard

Similarities in chromosomal puffing induced by temperature shocks and dinitrophenol in Drosophila

A comparison between chromosomal puffs induced by temperature shocks and dinitrophenol in regions 87 A and 87 B of salivary gland chromosome 3 R of Drosophila melanogaster is presented. The size of both puffs can be regulated by either the temperature of a heat-shock or by the concentration of dinitrophenol. The two agents are additive with respect to their effects upon puff size, supporting the idea that both result in a change in ATP synthesis within the cell. A possible relationship between these agents and puff formation and RNA metabolism is discussed.

The Locomotor Activity of Fish: An Analogy to the Kinetics of an Opposed First-Order Chemical Reaction

Abstract The kinetic behavior of a laboratory population of bluegill (Lepomis macrochirus) under defined laboratory conditions is shown to be analogous to the reaction kinetics described by a population of molecules engaged in an opposed (reversible) first-order reaction. Thus as in chemical kinetics, the locomotor activity of fish can be described quantitatively in the form of rate constants.

Nucleotide metabolism in Drosophila melanogaster salivary glands during temperature and dinitrophenol-induced puffing.

When Drosophila melanogaster salivary glands are exposed to temperature or dinitrophenol (DNP) treatments, their nucleotide metabolism is altered such that the amount of cellular ATP decreases, whereas the amount of ADP increases. Since both treatments also elicit specific puffing patterns on the salivary gland chromosome, it is suggested that specific loci on the chromosome are activated to form puffs when the efficiency of respiration decreases. The possible relationship between the formation of these puffs and the intramitochondrial metabolism is discussed.

The attraction of larvae of Culex pipiens quinquefasciatus Say to ribonucleic acid and nucleotides.

Abstract The positive chemotaxis of larvae of Culex pipiens quinquefasciatus in response to RNA or its degradation products has been demonstrated. It has further been shown that larvae are specifically attracted to certain nucleoside monophosphates. The observations are related to the known dietary requirements of mosquito larvae.