Disease relevance of Horseshoe Crabs

• As a result of treatment of bacterial lipopolysaccharide (LPS) by LPS-I, the treated LPS loses its toxicity for mice and reactivity in the Limulus assay and appears to be irreversibly disaggregated [1].
• Isolation and characterization of proteins that bind to galactose, lipopolysaccharide of Escherichia coli, and protein A of Staphylococcus aureus from the hemolymph of Tachypleus tridentatus [2].
• Compound 516 was also less active than compound 506 or natural E. coli lipid A (from Restrain F515) in other biological test systems, such as the Limulus test, stimulation of macrophages and lymphocytes, and interferon-inducing activity but not for interleukin-1 induction or complement activation [3].
• Addition of commercial heparin to preparations of the coagulation system obtained by hypotonic lysis of Limulus amebocytes, prior to the addition of endotoxin from gram-negative bacteria, inhibited gelation [4].
• Comparison of the histamine hypersensitivity and the Limulus amoebocyte lysate tests for endotoxin activity [5].

High impact information on Horseshoe Crabs

• All three residues mutated in DFNA9 are conserved in mouse and chicken Coch, and are found in a region containing four conserved cysteines with homology to a domain in factor C, a lipopolysaccharide-binding coagulation factor in Limulus polyphemus [6].
• Using the large ventral photoreceptor of the horseshoe crab (Limulus polyphemus) we describe a method for measuring the transient increase in the mitochondrial O2 consumption (delta QO2) following a flash of light of a single photoreceptor [7].
• We propose that one of the steps in the excitatory cascade in Limulus ventral photoreceptors may be an increase in intracellular concentration of myo-inositol polyphosphates, derived from hydrolysis of the membrane component phosphatidylinositol bisphosphate by a phospholipase [8].
• Efferent fibers to Limulus eyes synthesize and release octopamine [9].
• Excitation of Limulus photoreceptors by vanadate and by a hydrolysis-resistant analog of guanosine triphosphate [10].

Chemical compound and disease context of Horseshoe Crabs

• Corynebacterium parvum used was found devoid of endotoxin by the Limulus assay and was not affected by Polymyxin B, which, on the contrary, inhibited Escherichia coli-induced production of procoagulant activity [11].
• A serologically reactive, biologically active (Limulus assay) endotoxin was purified from phenol extracts of the Cytophaga species [12].
• Treatment of the LOS from strain ATCC 25238 with anhydrous hydrazine reduced its toxicity 20,000-fold, as assayed in the Limulus amebocyte lysate (LAL) test [13].
• Hepatitis B surface antigen was adsorbed to insolubilized sialic acid-specific haemagglutinin isolated from the haemolymph of Limulus polyphemus [14].
• These compounds, as well as dopamine, elicited sustained contractures and rhythmic contractions when applied to deganglionated Limulus cardiac muscle rings [15].

Biological context of Horseshoe Crabs

• We propose that outward movement of myosin heads and thick filament shortening in Limulus muscle are responses to activation that are dependent on phosphorylation of regulatory myosin light chains [16].
• A polyclonal antibody against the human COCH protein product, cochlin, was raised against the N-terminal 135 amino acid residues of cochlin, corresponding to the Limulus factor C-homology (cochFCH) domain; this domain harbors all five known point mutations in DFNA9 [17].
• Also, expressing Limulus opsin cDNA in the R1-R6 photoreceptors of transgenic Drosophila yielded a visual pigment that bound retinal, had normal spectral properties, and coupled to the endogenous phototransduction cascade [18].
• The Limulus Factor C (FC), a multidomain glycoprotein that binds bacterial endotoxin with high affinity, belongs to the serine protease family of the complement and blood coagulation cascade [19].
• The coding regions of the Limulus and human CRP genes share approximately 25% identity and two stretches of highly conserved regions, one of which falls in the region proposed as the phosphorylcholine binding site, while the other site is very similar to the consensus sequence required for calcium binding in calmodulin and related proteins [20].

Anatomical context of Horseshoe Crabs

• Our biochemical studies on the hemolymph coagulation-complement system using limulus indicate that the circulating hemocytes contain at least four serine protease zymogens and one clottable protein, coagulogen, which constitute a cascade triggered by bacterial endotoxins and (1,3)-beta-D-glucan [21].
• The discovery of lipopolysaccharide-sensitive and (1-->3)-beta-D-glucan-sensitive serine protease zymogens in horseshoe crab (limulus) hemocytes, both of which trigger the coagulation cascade, has exemplified how the animals detect and respond to foreign materials [22].
• Tropomyosin by itself increases the sliding velocity of actin filaments over phosphorylated Limulus myosin about 10-fold in a calcium-independent manner [23].
• In conclusion, the incorporation of lipopolysaccharide into the liposomal membrane probably prevents the interaction of the hydrophobic portion of the lipid A component of lipopolysaccharide with the plasma-membrane structures involved in the activation of macrophages and with the proteins of the Limulus amoebocyte lysate [24].
• Conversely, the helper T cell activity that was induced by Lens culinalis agglutinin and separated by Limulus polyphemus agglutinin, was eliminated by treatment of the cells with anti-GM1 and complement, but not by the treatment with the other anti-glycolipid antisera and complement [25].

Associations of Horseshoe Crabs with chemical compounds

• Both photons and fluoride ions excite limulus ventral photoreceptors [26].
• The active component is heat stable, reacts positively in the Limulus amebocyte lysate assay, and can be inhibited by polymyxin B [27].
• Feedback inhibition by calcium limits the release of calcium by inositol trisphosphate in Limulus ventral photoreceptors [28].
• Limulus polyphemus lectin (LPA), with specificity for N-acetylneuraminic acid, did not influence the binding of HPA but enhanced the binding of DBA [29].
• This same water after ethylene oxide sterilization contained 2 x 10(5) ng/mL of endotoxin by limulus lysate test and was positive by rabbit pyrogen test [30].

Gene context of Horseshoe Crabs

• Both forms of LBP bound to LPS with the same affinity, and similarly inhibited LPS activity in the Limulus amebocyte lysate assay [31].
• Besides leukocytes, C3a, C5a, and limulus amebocyte lysate reactivity, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-6, IL-1RA, soluble TNF receptors, and IL-1 beta mRNA were assessed [32].
• These data suggest, if the synergism between IFN and endotoxin also operates in the homologous system (human IFN-human cells), that contaminating endotoxin in IFNs, even if not detectable by Limulus amoebocyte lysate test, can contribute to IFN fever to a considerable extent in humans [33].
• Nonpyrogenic amounts of endotoxin (0.1 to 1 ng/kg), hardly detectable by conventional Limulus amoebocyte lysate tests, could produce a fever of around 1 degree C when injected with a nonpyrogenic dose (6 X 10(5) U/kg) of recombinant human beta interferon (IFN-beta) in rabbits [33].
• Akhirin consists of one LCCL (Limulus factor C, Coch-5b2, and Lgl1) domain and two von Willebrand factor domains and displays high structural homology to vitrin and cochlin [34].

Analytical, diagnostic and therapeutic context of Horseshoe Crabs

• The apparent native molecular weight for the Limulus molecule as determined by both gel filtration and gel electrophoresis under nonreducing conditions is 500,000-550,000, compared to a native molecular weight of 700,000-750,000 for human alpha 2M, determined in parallel under identical conditions [35].
• Sequence analyses of peptides derived from enzymatic and chemical cleavages of affinity purified Limulus CRP indicate that subunits other than the three mentioned above exist in the hemolymph [36].
• Digestion of the native subunits of Limulus hemocyanin by formic acid or trypsin shows considerable structural diversity which is supported by cyanogen bromide cleavage patterns and by peptide mapping of the tryptic peptides prepared from denatured hemocyanin subunits [37].
• Electrophoretic mobility shift assay further confirmed a strong interaction of the limulus kappaB motif with Rel proteins [38].
• The envelope protein preparations had no detectable endotoxin as tested by the Limulus amebocyte lysate assay, and hence we can rule out the effect of contaminating endotoxin, which is a potent inducer of IL-6 in monocyte/macrophage cell cultures [39].

References