Eyes of Molluscs and Arthropods

gamma -Glutamyl carboxylation: An extracellular posttranslational modification that antedates the divergence of molluscs, arthropods, and chordates.

The posttranslational gamma-carboxylation of glutamate residues in secreted proteins to gamma-carboxyglutamate is carried out by the vitamin K-dependent enzyme gamma-glutamyl carboxylase. gamma-Carboxylation has long been thought to be a biochemical specialization of vertebrates, essential for blood clotting. Recently, a gamma-carboxylase was shown to be expressed in Drosophila, although its fu...

Molluscs

Figure 1. The ‘Kraken’ myth. Ancient tales repeatedly reported octopod-like sea-monsters attacking sea vessels. Indeed, octopuses may reach a maximum of 3 m body size, but the foundation of these ancient tales is based on giant squids (with ten rather than eight arms as depicted here) defending itself against its main predator, a sperm whale, rather than octopuses. Squids are known to leave suc...

Cockroaches, locusts, and envenomating arthropods: a promising source of antimicrobials

Objective(s): To present a brief overview of various natural sources of antimicrobials with the aim of highlighting invertebrates living in polluted environments as additional sources of antimicrobials. Materials and Methods: A PubMed search using antibacterials, antimicrobials, invertebrates, and natural products as keywords was carried out. In addition, we consulted conference proceedings, or...

Arthropods: Spiders and Peatlands

Lysozymes in molluscs

Invertebrates lack antibody-mediated humoral immune systems; however, they are believed to possess efficient host defense mechanisms involving humoral defense molecules that are similar in function to antibodies. Lysozymes are a group of enzymes that cleave the glycosidic bonds between N-acetylmuramic acid and N-acetylglucosamine (two amino sugars) in the peptidoglycans that form bacterial cell...