[Scorpionidae of the great Arabic Maghreb. V. A telson with three stings in Buthus occitanus Amoureux]. / Contribution à l'étude des Scorpionidae du grand Maghreb Arabe. V. - A propos d'un telson à trois aiguillons chez Buthus occitanus Amoureux.

The authors describe telson anomaly of scorpion Buthus occitanus and compare it with other anomalies described in Algeria.

A refined quaternary structure of Androctonus australis Hemocyanin.

The quaternary structure of the (4 X 6)-mer hemocyanin from the Scorpion Androctonus australis previously published [Lamy, J., Bijlholt, M. M. C., Sizaret, P.-Y., Lamy, J., and van Bruggen, E. F. J. (1981) Biochemistry, 20, 1849-1856] has been refined. The relative positions in the half molecule of subunits Aa 3A and Aa 3B compared to those of Aa 3C and Aa 5B have been established by double labeling of the (2 X 6)-mer with binary mixtures of subunit-specific Fab fragments. The results show that subunits Aa 3B and Aa 5B are located in the same hexamer while Aa 3A and Aa 3C are in the other half of the (2 X 6)-mer. The choice of the enantiomer was deduced from a careful examination of electron micrographs of the native molecule. Finally a position was assigned to each of the 24 subunits on the flip and flop faces as defined by Van Heel and Frank [Ultramicroscopy, 6, 187-194 (1981)].

Immunological correspondence between arthropod hemocyanin subunits. I. Scorpion (Leiurus, Androctonus) and spider (Eurypelma, Cupiennius) hemocyanin.

The hemocyanins of the scorpions Leiurus quinquestriatus and Androctonus australis, the tarantula Eurypelma californicum (all 24-mers), and the lycosid spider Cupiennius salei (dodecamer) were dissociated into subunits, the subunits isolated and studied by two-dimensional immunoelectrophoresis for interspecific cross-reactivities. Androctonus hemocyanin yielded a pattern of 8 subunit types in agreement with data from Lamy et al. (1979, Arch. Biochem. Biophys. 193, 140-149). Leiurus hemocyanin is also composed of 8 immunologically distinct subunits which could be assigned to the pattern of Androctonus in a subunit-to-subunit correlation. The subunit designations 1 to 6 of Lamy et al. could be adopted for both scorpion hemocyanins; however, in the present communication, Lamy's subunits 3A/3B are designated as 3'/3", because we could not unequivocally decide if 3' = 3A and 3" = 3B or vice versa. The 7 subunit types a to g of Eurypelma hemocyanin could be correlated with the scorpion hemocyanin subunits as follows: a = 3', b = 5B, c = 3C, d = 5A, e = 6, f = 2, g = 4. Additional cross-reactivities were detected between e/4, and f/5A, respectively. No subunit of Eurypelma hemocyanin is homologous to scorpion 3", which could not be precipitated by anti-Eurypelma antiserum. Antiserum against Cupiennius hemocyanin precipitated subunit f of Eurypelma and subunits 2 and 5A of scorpion hemocyanin. The published models of quaternary structure and a possible subunit phylogeny of arachnidan hemocyanins are discussed in view of the present results.

An anti-insect toxin purified from the scorpion Androctonus australis Hector also acts on the alpha- and beta-sites of the mammalian sodium channel: sequence and circular dichroism study.

A new anti-insect neurotoxin, AaH IT4, has been isolated from the venom of the North African scorpion Androctonus australis Hector. This polypeptide has a toxic effect on insects and mammals and is capable of competing with anti-insect scorpion toxins for binding to the sodium channel of insects; it also modulates the binding of alpha-type and beta-type anti-mammal scorpion toxins to the mammal sodium channel. This is the first report of a scorpion toxin able to exhibit these three kinds of activity. The molecule is composed of 65 amino acid residues and lacks methionine and, more unexpectedly, proline, which until now has been considered to play a role in the folded structure of all scorpion neurotoxins. The primary structure showed a poor homology with the sequences of other scorpion toxins; however, it had features in common with beta-type toxins. In fact, radioimmunoassays using antibodies directed to scorpion toxins representative of the main structural groups showed that there is a recognition of AaH IT4 via anti-beta-type toxin antibodies only. A circular dichroism study revealed a low content of regular secondary structures, particularly in beta-sheet structures, when compared to other scorpion toxins. This protein might be the first member of a new class of toxins to have ancestral structural features and a wide toxic range.