Biosynthesis of Quinoline by a Stick Insect.

The Peruvian stick insect is the only known animal source for unsubstituted quinoline in nature. When disturbed, these insects discharge a defensive secretion containing quinoline. Analysis of samples obtained from l-[2',4',5',6,'7'-H]tryptophan-fed stick insects demonstrated that the insects convert it to [5,6,7,8-H]quinoline by removing the 2'-CH moiety in the indole ring of tryptophan.

Biological bifocal lenses with image separation.

Almost all animal eyes follow a few, relatively well-understood functional plans. Only rarely do researchers discover an eye that diverges fundamentally from known types. The principal eye E2 of sunburst diving beetle (Thermonectus marmoratus) larvae clearly falls into the rarer category.

Eye and optic lobe metamorphosis in the sunburst diving beetle, Thermonectus marmoratus (Coleoptera: Dytiscidae).

Nearly nothing is known about the transition that visual brain regions undergo during metamorphosis, except for Drosophila in which larval eyes and the underlying neural structure are strongly reduced. We have studied the larvae of the sunburst diving beetle, Thermonectus marmoratus (Coleoptera: Dytiscidae), which are sophisticated visually oriented predators characterized by six elaborate stemmata on each side of the head and an associated large optic lobe. We used general neurohistological staining and 3D reconstruction to determine how the eyes and optic lobe of T.

Scanning behavior by larvae of the predacious diving beetle, Thermonectus marmoratus (Coleoptera: Dytiscidae) enlarges visual field prior to prey capture.

Larvae of the predaceous diving beetle Thermonectus marmoratus bear six stemmata on each side of their head, two of which form relatively long tubes with linear retinas at their proximal ends. The physical organization of these eyes results in extremely narrow visual fields that extend only laterally in the horizontal body plane. There are other examples of animals possessing eyes with predominantly linear retinas, or with linear arrangements of specific receptor types.

Twenty-eight retinas but only twelve eyes: an anatomical analysis of the larval visual system of the diving beetle Thermonectus marmoratus (Coleoptera: Dytiscidae).

The larvae of the sunburst diving beetle, Thermonectus marmoratus (Coleoptera: Dytiscidae), are highly efficient visually guided predators. Their visual system consists of a cluster of six stemmata and one eye patch on each side of the head capsule. Histological investigations show that the organization of individual stemmata differs strongly from any eye that has previously been described.