On-transient of insect electroretinogram: its cellular origin.

Electrical responses to light stimuli were recorded intracellularly from the retinula cells and the laminar cells of the wild type and the x-7 mutant of Drosophila melanogaster in order to determine the cellular origin of the on-transient of the insect electroretinogram. The response of the retinula cell of the mutant x-7 closely resembles that of the wild type even though the ontranstent is absent from the electroretinogram of x-7. Neither contains a spike-like component that can be identified with the on-transient of the electroretinogram. However, a spike-like response resembling the on-transient in latency and time course has been obtained from one of the several types of cells in the lamina of the wild type. Moreover, the same response could not be obtained from the laminar cells of the mutant x-7. Thus, the on-transient does not appear to originate from the retinula cell but probably from one or more of several types of cells in the lamina.

Catecholamines in Drosophila melanogaster (wild type and ebony mutant) decuticalarized retinas and brains.

The concentrations of catecholamines were determined in the decuticalarized retinas and brains at different ages in wildtype and ebony Drosophila melanogaster using the HPLC-technique with an electrochemical detector. L-Dopa, dopamine (DA), alpha-methyldopa (alpha-MD) and unidentified compounds X1, X2 and X3 were found in decuticalarized retinas and brains of wildtype and ebony at different ages. Retinas and brains of the mutant ebony have higher concentrations of L-Dopa, DA and alpha-MD than the wildtype. In both wildtype and ebony, the concentrations of X1, X2 and X3 were found to be higher in decuticalarized retinas than in brains. The identity and importance of X1, X2 and X3 are still unknown.