1. Shark repellent lipophilic constituents in the defense secretion of the Moses sole (Pardachirus marmoratus)
K Tachibana, S H Gruber Toxicon. 1988;26(9):839-53. doi: 10.1016/0041-0101(88)90325-x.
The defense secretion of Moses sole (Pardachirus marmoratus), the fish known to repel sharks, contains lipophilic ichthyotoxins in addition to pardaxin, a peptidic ichthyotoxin. Pardaxin has previously been regarded as the only factor responsible for the shark repellency of the secretion. On the basis of the shark repellent activity observed with the lipophile, it is considered to participate in the repellency of the secretion. Further separation of the toxic lipophile yielded five steroid monoglycosides, named mosesins. Their structures have been elucidated by nuclear magnetic resonance spectroscopy and corroborated by correlating them spectroscopically or chemically to cholic acid or to pavoninins, the related glycosides isolated from the secretion of the congeneric peacock sole, P. pavoninus.
2. Pavoninins: shark-repelling ichthyotoxins from the defense secretion of the pacific sole
K Tachibana, M Sakaitanai, K Nakanishi Science. 1984 Nov 9;226(4675):703-5. doi: 10.1126/science.226.4675.703.
A series of ichthyotoxic and hemolytic steroid aminoglycosides, pavoninins-1, to -6, has been isolated from the defense secretion of the sole Pardachirus pavoninus, and their respective chemical structures have been established by spectroscopic studies and chemical conversions. The pavoninins exert repellent activity against sharks and are considered to be the factors responsible for the predator-repelling property of the sole.
3. Purification and pore-forming activity of two hydrophobic polypeptides from the secretion of the Red Sea Moses sole (Pardachirus marmoratus)
P Lazarovici, N Primor, L M Loew J Biol Chem. 1986 Dec 15;261(35):16704-13.
A new column chromatography procedure, based on ion exchange, chromatofocusing, and reverse phase high pressure liquid chromatography was employed to isolate the two main proteinaceous, toxic, cytolytic, pore-forming factors from the secretion of the Red Sea Moses sole Pardachirus marmoratus. Pardaxin I, comprising 10% of the gland secretion proteins, was shown to be 5-10 times more toxic, cytolytic, and active in membrane pore formation than pardaxin II (8% of gland secretion proteins). Gel electrophoresis, amino acid analysis, and NH2-terminal amino acid sequence reveals a high degree of homogeneity and resemblance between the two toxins. They are rich in aspartic acid, serine, glycine, and alanine and devoid of arginine, tyrosine, and tryptophan. Their NH2-terminal residue sequence was found to be NH2-Gly-Phe-Phe. Their hydrophobicity is evident from chromatographic behavior on a hydrophobic matrix, presence of 9 successive hydrophobic residues at the NH2 terminus, and a decrease in drop size during elution of active fractions during chromatographic purification. The minimal molecular weight of pardaxin I is about 3500 as determined by sodium dodecyl sulfate gel electrophoresis and amino acid analyses. It is composed of 35 amino acids and is free of carbohydrate and sialic acid residues. Mass spectrometry of the ethyl acetate extract of the gland secretion and purified toxin reveals the presence of sterols in the secretion but their absence in the purified toxins. Pardaxin I was iodinated without affecting its chemical and pore-forming properties. It binds to liposomes of different phospholipid compositions. In hyperpolarized unilamellar liposomes, pardaxin I produced a fast, nonspecific permeabilization and in multilamellar liposomes, a slow, cation-specific pore. It is suggested that pardaxins exert their effects due to their hydrophobic and pore-formation properties.
