English: Comparison of Toll pathways among mammals, Drosophila, and shrimp. In mammals, lipopolysaccharide (LPS) activates the Toll-like receptor (TLR) pathway by directly binding to the TLR4 receptor. In Drosophila, G + bacteria or fungi activate the Toll pathway by functional Spätzle binding to Toll. In shrimp, G + bacteria and G − bacteria all can activate the Toll pathway by their pathogen-associated molecular patterns directly binding to Toll receptors. In shrimp, Toll receptors can directly bind to G + and G − bacteria, whether the Spätzles participated in the Toll pathway (like Drosophila) in shrimp still needs further study.