Ricerche sul differenziamento genetico di Ascaris lumbricoides e Ascaris suum

Nascetti, Giuseppe ; Grappelli, Claudio ; Bullini, Luciano

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 67 (1979) no. 6, pp. 457-465

Résumé

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).