The taxonomic status and the genetic differentiation of human ascaris (Ascaris lumbricoides) and pig ascaris (A. suum) was investigated by means of electrophoretic studies at the following enzyme loci: Sdh, Ldh, Mdh-1, Mdh-2, Mdh-3, Idh-1, 6-Pgdh, G-6-pdh, G-3-pdh, Got-1, Got-2, Adk, Pgm-1, Pgm-2, Est-1, Est-2, Acph, Aldo, Tpi, Mpi and Phi. The results obtained clearly show that A. lumbricoides and A. suum are genetically well-differentiated species, easily and surely identifiable by electrophoresis. Four enzyme loci (Mdh-3, G-6-pdh, Est-2 and Aldo) out of the twenty-one tested appear to be fully diagnostic between A. lumbricoides and A. suum, while another one (Phi) is partially diagnostic (minimum probability of correct identification > .90). Polymorphism according to the 1% criterion was observed at Got-1, Pgm-1, Mpi and Phi loci in both species and at Got-2 and Est-2 only in A. lumbricoides. Rare variants were observed in A. suum at G-6-pdh, Adk and Est-1 loci. The observed mean heterozygosity per locus was 2.69% for A. lumbricoides and 3.81% for A. suum. These values are significantly higher than those observed in the species of the genus Parascaris. The average genetic distance (D) between A. lumbricoides and A. suum, calculated with Nei's index, is 0.315 (genetic identity (I) = 0.729); such values indicate that these two species are the product of a relatively recent process of speciation (about 1.6 million years).
Referenze Bibliografiche
[1] S. Abdulrachman e Lie Kian Joe (1954) - Morphological differences between Ascaris from man and pig. «Documente de Medicina Geographica et Tropica», 6, 342-344.
[2] M. Ansel e M. Thibaut (1973) - Value of the specific distinction between Ascaris lumbricoides Linné 1758 and Ascaris suum Goeze 1782, «Int. J. for Paras.», 3, 317-319.
[3] F.J. Ayala (1975) - Genetic differentiation during the speciation process. «Evolutionary Biology», 8, 1-78.
[4] F.J. Ayala, J.R. Powell, M.L. Tracey, C.A. Mourao e S. Perez-Salas (1972) - Enzyme variability in the Drosophila willistoni group. IV. Genic variation in natural populations of Drosophila willistoni. «Genetics», 70, 113-139.
[5] J.M. Barry e F.J. O'Rourke (1967) — Ascariasis in pig and Man. «Sc. proc. of Dublin Soc.», serie A, 3(4), 39-55.
[6] E. Biocca, G. Nascetti, A. Iori, R. Costantini e L. Bullini (1978) - Descrizione di Parascaris univalens, parassita degli equini e suo differenziamento da Parascaris equorum. «Acc. Naz. Lincei, Rend. Cl. Se. Fis., Mat. e Nat.», 65, 133-140.
[7] G.J. Brewer (1970) - An Introduction to Isozyme Techniques. Academic Press, New York.
[8] L. Bullini, G. Nascetti, S. Ciafrè, F. Rumore e E. Biocca (1978) - Ricerche cariologiche ed elettroforetiche su Parascaris univalens e Parascaris equorum. «Acc. Naz. Lincei, Rend. Cl. Sc. Fis., Mat. e Nat.», 65, 151-156.
[9] W. Crewe e D.H. Smith (1971) - Human infection with pig Ascaris (A. suum), «Ann. Trop. Med. and Paras.», 65.
[10] N.J. Davies e J.M. Goldsmid (1978) - Intestinal obstruction due to Ascaris suum infection. «Trans. of Roy. Soc. Trop. Med. Hyg.», 72, 107.
[11] I. de Carneri (1978) - Parassitologia generale e umana. 6a ed., Casa Editrice Ambrosiana, Milano.
[12] J.M. Goldsmid (1976) - Ascariasis in Rhodesia. «Centr. Afr. J. of Med.», 22, 220.
[13] I.G. Kagan (1957) - Serum agar double diffusion studies with Ascaris antigens. «J. of inf. dis.», 101, 11-19.
[14] A.D. Logue, A.B. Chowdhury e E.L. Schiller (1963) - Comparative serological reactions of Ascaris lumbricoides and Ascaris lumbricoides var. suum extracts in agar gel. «Bull. of Calcutta Sc. of Trop. Med.», 11, 129-131.
[15] H. Lysek (1963) - Contribution to the morphological problem of differences between Ascaris lumbricoides Linné 1758 and Ascaris suum Goeze 1782. «Vestnik Ceskoslovenské Spolecnosti Zoologikcé», 27, 91-101.
[16] M. Nei (1972) - Genetic distance between populations. «Amer. Natur.», 106, 283-292.
[17] M. Nei (1975) - Molecular Populations Genetics and Evolution. North-Holland, American Elsevier, Amsterdam-New York.
[18] J.A. Phills, A.J. Harrold, G.V. Whiteman e L. Perelmutter (1972) - Pulmonary infiltrates, asthman and eosinophilia due to Ascaris suum infection in man. «New England J. of Med.», 286, 965.
[19] R.K. Selander, M.H. Smith, S.Y. Yang, W.E. Johnson e J.B. Gentry (1971) - Biochemical polymorphism in the genus Peromyscus. I. Variation of the old-field mouse (Peromyscus polionotus). Studies in Genet., Univ. Texas publ. N. 7103. 49-90.
[20] C.R. Shaw e A.L. Koen (1968) - Starch gel zone electrophoresis of enzymes. In: Chromatographic and Electrophoretic Techniques Vol. 2, 2nd ed., I. Smith e J. Wiley editors, New York.
[21] J.F.A. Sprent (1952) - Anatomical Distinction between Human and Pig Strains of Ascaris. «Nature», 170, 627-628.
[22] D.S. Zee e W.H. Zinkham (1968) - Malate dehydrogenase in Ascaris suum: Charaterization, ontogeny and genetic control. «Arch. Biochem. Biophys.», 126, 574.
[23] D.S. Zee, H. Isensee e W.H. Zinkham (1970) - Polymorphism of Malate Dehydrogenase in Ascaris suum. «Biochem. Genet.», 4, 253-257.
Con il contributo del Ministero per i Beni e le Attività Culturali