Karyotype Analysis of Two Paramphistomes Infecting Nile Fish

Abstract

Summary Paramphistomes are intestinal parasitic warms infecting a wide range of vertebrate animals and are considered, by various authors, as the most primitive digenetic trematodes. The karyotypes of Sandonia sudanensis McClelland, Basidiodiscus ectorchis Fischthal and Kuntz inhabiting a common fish host, and Synodontis schall Bloch-Scheinder were studied. We recorded that both Sandonia sudanensis and Basidiodiscus ectorchis have the same number of chromosomes with diploid number 2nϭ12 and nϭ6 at the end of meiotic divisions. As far as the authors know, the present work is the first chromosomal study of these 2 fish paramphistomes and the first karyological observation of fish-infecting paramphistomes. The results are discussed and compared with that of mammalian paramphistomes. Paramphistomes, Karyotype. Paramphistomes are intestinal parasitic warms infecting a wide range of vertebrate animals and are considered, by various authors, as the most primitive digenetic trematodes. Trematodes and cestodes, which are the major groups of phylum platyhelminthes, form a monophyletic taxon known as the Neodermata (Ehlers 1985) that is suggested by Rohde (1994) as a parasitic taxon either living in or on a host. Key wordsAlthough Barsiene (1993) and Barshene (1993) reviewed the chromosome numbers and the karyological data for 96 and 230 species of trematodes respectively, still and till recently, there have been relatively few studies on the chromosomes of digenetic trematodes. Concerning paramphistomes, several chromosome studies were carried out by Sey (1971), Grossman and Cain (1981), Mutafova (1983), Rhee et al. (1986Rhee et al. ( , 1987Rhee et al. ( , 1988, Li and He (1987), Barsiene (1991) and Ashour et al. (1995).The aim of the present work is to describe both the chromosome number and structure and to analyze the karyotypes of the 2 amphistomes Sandonia sudanensis and Basidiodiscus ectorchis collected from the fish Synodontis schall and comparing the result with that of other paramphistomes. Materials and methodsSynodontis schall fishes were collected from fishermen working in the area of El-Giza (ElBahr El-Aazam) and then dissected and the alimentary canal was opened. Living worms: Sandonia sudanensis McClelland and Basidiodiscus ectorchis Fischthal and Kuntz were put separately according to the species in 0.005% colchicine in saline (0.7% NaCl) for 2 h. The whole worms or sometimes isolated testes were minced using fine scissors and Pasteur pipettes, and then put in hypotonic solution of KCl (0.48%) for 30 min. The fixative 3 : 1 methanol : acetic acid was added and left for 2 h. Centrifugation was carried out at 2000 rpm for 10 min; the supernatant fluid was dis-

Spermiogenesis in two paramphistomes from Nile fish in Egypt: an ultrastructural study

“…This view was confirmed by Grossman & Cain (1981) and Ashour et al (1995) who recorded acrocentric chromosomes respectively in the amphistomes Megalodiscus temperatus, Calicophoron microbothrium and Carmyerius gregarius. However, in the present study, spermiogenesis together with the karyotype of S. sudanensis and B. ectorchis and the absence of any acrocentric chromosomes (Ashour et al, 2006) suggest that the two species belong to more advanced amphistomes. However, in the present study, spermiogenesis together with the karyotype of S. sudanensis and B. ectorchis and the absence of any acrocentric chromosomes (Ashour et al, 2006) suggest that the two species belong to more advanced amphistomes.…”

“…These authors regarded the karyotype as showing a lesser degree of evolution in chromosomal configuration than any other member of the digenetic trematodes. However, in the present study, spermiogenesis together with the karyotype of S. sudanensis and B. ectorchis and the absence of any acrocentric chromosomes (Ashour et al, 2006) suggest that the two species belong to more advanced amphistomes.…”

“…The karyotype of B. ectorchis and S. sudanensis previously described by Ashour et al (2006) consisted mostly of metacentric chromosomes, although White (1973) showed that a primitive karyotype within any given phyletic group consists typically of acrocentric chromosomes. This view was confirmed by Grossman & Cain (1981) and Ashour et al (1995) who recorded acrocentric chromosomes respectively in the amphistomes Megalodiscus temperatus, Calicophoron microbothrium and Carmyerius gregarius.…”