The interplay between the complement and coagulation systems is just beginning to be explored and characterized. This interaction, however, is ancient. For example, if endotoxin is added to the hemolymph of the horseshoe crab, a protease is activated that triggers both the coagulation and complement systems. However, in extant mammals, these 2 cascades have diverged. These infamous "terrible C'...

Fossilised arthropod compound eyes have frequently been described. Among the oldest known are those from the lower Cambrian of the Chengjiang Lagerstätte (China, c 525 Ma). All these compound eyes, though often excellently preserved, however, represent just the outer shells, because soft tissues, or even individual cells, usually do not fossilise. Using modern techniques, including μct-scanning...

The purpose of this contribution is to review our current understanding of the source and biochemistry of the circadian efferent input to the eyes of the American horseshoe crab Limulus polyphemus and the impact of this input on the structure, physiology and biochemistry of Limulus eyes. Special emphasis is given to the role of the biogenic amine octopamine and biochemical cascades it activates...

Animals as well as plants defend themselves against invading pathogenic microorganisms utilizing cationic antimicrobial peptides, which rapidly kill various microbes without exerting toxicity against the host. Physicochemical peptide-lipid interactions provide attractive mechanisms for innate immunity. Many of these peptides form cationic amphipathic secondary structures, typically alpha-helice...

The acrosomal process of the sperm of the horseshoe crab (Limulus polyphemus) is a unique crystalline actin bundle, consisting of multiple actin filaments cross-linked by the actin-bundling protein, scruin. For successful fertilization, the acrosomal bundle must penetrate through a 30 microm thick jelly coat surrounding the egg and thus it must be sufficiently stiff. Here, we present two measur...

Actin-based motility in cells is usually associated with either polymerization/depolymerization in the presence of cross-linkers or contractility in the presence of myosin motors. Here, we focus on a third distinct mechanism involving actin in motility, seen in the dynamics of an active actin spring that powers the acrosomal reaction of the horseshoe crab (Limulus polyphemus) sperm. During this...

The pentraxins are a family of highly conserved plasma proteins of metazoans known to function in immune defence. The canonical members, C-reactive protein and serum amyloid P component, have been identified in arthropods and humans. Mammalian pentraxins are known to bind lipid bilayers, and a pentraxin representative from the American horseshoe crab, Limulus polyphemus, binds and permeabilizes...

Sushi peptides [S1 (Sushi 1 peptide) and S3] are derived from the LPS (lipopolysaccharide; also known as endotoxin)-binding domains of an LPS-sensitive serine protease, Factor C, from the horseshoe crab (Carcinoscorpius rotundicauda). S1 and S3 interact at high affinity with LPS. The intermolecular disulphide bonding in the S3 dimer is indispensable for its LPS binding, disruption and consequen...

Lysates obtained from amoebocytes of Limulus polyphemus, the horseshoe crab, showed gel formation after the addition of bacterial endotoxin. In contrast to living gram-negative bacteria, viable gram-positive microorganisms did not cause gelation of lysate. Nevertheless, peptidoglycan isolated from the cell walls of various gram-positive organisms did induce the reaction. However, the activity o...

Carbohydrate-binding lectins play essential roles as pattern recognition receptors in innate immunity in both vertebrates and invertebrates. The carcinolectins 5 (CL5a and CL5b, the CL5 isoforms of horseshoe crab, Carcinoscorpius rotundicauda, with apparent sizes of 36 and 40 kDa, respectively) are prominent plasma lectins that bind all representative microbes and pathogen-associated molecular ...