Suppression of Tryptophan 2,3-Dioxygenase Produces a Slow Heartbeat Phenotype inDrosophila melanogaster

Abstract

The primary pathway utilizing tryptophan leads initially to kynurenine before branching. Products include nicotinamide adenine dinucleotide and important pigments in the eye. Products in this pathway have been linked to a number of pathologies. The gene encoding the first step in this pathway, tryptophan 2,3-dioxegenase, is encoded by the gene vermilion, initially discovered in Drosophila. In the fly, v is an important eye color marker, but is found to have multiple pleiotropic effects. We have uncovered significant effects of this mutation on the fly heart. The heart beats more slowly and more rhythmically in both males and females and in strains which we have outcrossed. In addition, the fly heart normally beats irregularly with multiple brief stoppages, and the time structure of these stoppages, as investigated by looking at interbeat intervals, is changed in flies bearing this mutation. Fewer flies bearing the v mutation show long hiatuses in beat compared to wild type, however, in some strains of the mutant animals that do, the number of stoppages in much greater and the mean duration is longer.

Probiotic potentials of the silkworm gut symbiont Enterococcus casseliflavus ECB140, a promising L-tryptophan producer living inside the host

“…In insects, L‐tryptophan is an essential amino acid required in several physiological processes of insects apart from protein synthesis. These include the synthesis of kynurenine, eye chromes, picolinic acid and nicotinamide adenine dinucleotide (NAD) (Beasley & Dowse, 2016; Ze et al, 2021). In cabbage butterfly, Pieris brassicae , the lack of tryptophan leads to a decrease in xanthommatin which accumulates in the larval epidermis as a brown‐red pigment during the larval feeding period.…”

Limulus and heart rhythm

“…In Drosophila melanogaster , the HR is age dependent and at the prepupal stage it reaches ~170 beats min −1 (Choma, Suter, Vakoc, Bouma, & Tearney, ). Note that at this stage, flies are “white‐translucent” that enables a convenient observation of heartbeat similar to other invertebrates (Beasley & Dowse, ; V. L. Zhuravlev et al, ). In some studies, they are placed in either physiological solutions or in a “drop of water which increased the intensity of the illumination and served to help keep the pupa” (Beasley & Dowse, ) at experimentally controlled temperatures up to 37°C.…”