Gr. endon: within + L. toxicum: poison] • Lipopolysaccharides released by the lysis of some Gram-negative bacteria that cause fever and vomiting in a host organism. Energetic cost • The difference between the energy an animal would have expended had it rested, and that expended in performing a behavior.

Harmful substances that are contained within the cells that produce them, or are integral constituents of cellular structure and are not released until the cell disintegrates.

Toxins produced by bacteria.

Proteins that are produced primarily by gramnegative bacteria; these toxins are released by bacterial disintegration caused by antibiotics or phagocytosis.