A comparison of the internal transcribed spacer of the ribosomal DNA for Eubothrium crassum and Eubothrium salvelini (Cestoda: Pseudophyllidea), parasites of salmonid fish.

The internal transcribed spacers (ITS-1 and ITS-2) and 5.8S subunit of the ribosomal RNA gene of Eubothrium crassum and Eubothrium salvelini, cestode parasites of salmonid fish, were sequenced and compared. The lengths and GC contents of the regions sequenced were 1119 bp and 50.1% for E. crassum, and 1117 bp and 50.5% for E. salvelini, respectively. Sequence alignment and comparison of both taxa showed 97.9% similarity. Within the ITS-1 and ITS-2 of both species, the restriction enzymes MspI and Bsh1236I possessed different cleavage sites and could be employed for rapid differentiation of both species of Eubothrium by PCR-RFLP.

A karyological study of the spirurid nematode Mastophorus muris (Nematoda: Spirocercidae).

The karyotype of Mastophorus muris (Gmelin, 1790) comprises four pairs of small autosomal chromosomes and two larger sex X chromosomes in females or one X chromosome in males (2n = 8 + XX/XO). All pairs of chromosomes possess rather uniform morphology without distinct primary or secondary constrictions. No heterochromatin bands were found by C-banding analysis. The absolute chromosome length ranges from 4.02 to 2.24 microns. The mean total length of the haploid complement is 14.34 microns. The course of gametogenesis represents a typical pattern common in the order Spirurida. The recently available karyotypes of spirurid nematodes have been reviewed.

Analysis of ribosomal RNA genes suggests that trypanosomes are monophyletic.

To further investigate the phylogeny of protozoa from the order Kinetoplastida we have sequenced the small subunit (SSU) and a portion of the large subunit (LSU) nuclear rRNA genes. The SSU and LSU sequences were determined from a lizard trypanosome, Trypanosoma scelopori and a bodonid, Rhynchobodo sp., and the LSU sequences were determined from an insect trypanosomatid, Crithidia oncopelti, and a bodonid, Dimastigella trypaniformis. Contrary to previous results, in which trypanosomes were found to be paraphyletic, with Trypanosoma brucei representing the earliest-diverging lineage, we have now found evidence for the monophyly of trypanosomes. Addition of new taxa which subdivide long branches (such as that of T. brucei) have helped to identify homoplasies responsible for the paraphyletic trees in previous studies. Although the monophyly of the trypanosome clade is supported in the bootstrap analyses for maximum likelihood at 97% and maximum parsimony at 92%, there is only a small difference in ln-likelihood value or tree length between the most optimal monophyletic tree and the best suboptimal paraphyletic tree. Within the trypanosomatid subtree, the clade of trypanosomes is a sister group to the monophyletic clade of the nontrypanosome genera. Different groups of trypanosomes group on the tree according to their mode of transmission. This suggests that the adaptation to invertebrate vectors plays a more important role in the trypanosome evolution than the adaptation to vertebrate hosts.

Karyotype of an avian schistosome Trichobilharzia szidati (Digenea: Schistosomatidae).

Somatic chromosomes of Trichobilharzia szidati Neuhaus, 1952 are described from larval stages dissected from snails, air-dried on slides and stained with Giemsa and C-banding technique, used for the first time in Trichobilharzia sp. The karyotype consisted of 7 autosomal pairs and 1 pair of sex chromosomes, ZZ in the male and ZW in the female, where Z and W chromosomes are of different sizes and both are classified as submetacentric. C-banding aided in identification of chromosomes Nos 4, satellited 6 and 8. No heterochromatin was observed in the W chromosome. The results were not in agreement with those previously reported and represent new findings. The possible explanation for this fact is given.

Intraspecific variability of Proteocephalus exiguus La Rue, 1911 (Cestoda: Proteocephalidae) as studied by the random amplified polymorphic DNA method.

The intraspecific variability of Proteocephalus exiguus, a common fish cestode, was studied by the random amplified polymorphic DNA method. Isolates from four distant localities and four host species were investigated using eight arbitrary decamer oligonucleotides as primers. A relatively high variation of RAPD fingerprints from individual strobila was detected. The constant fragments observed in all isolates detected by eight primers characterized the species studied.

A total DNA characterization in Proteocephalus exiguus and P. percae (Cestoda: Proteocephalidae): random amplified polymorphic DNA and hybridization techniques.

Two morphologically similar fish tapeworms, Proteocephalus exiguus and P. percae, were differentiated by the random amplified polymorphic DNA (RAPD) marker and Southern-blot hybridization techniques. Four geographic isolates of P. exiguus and two of P. percae were studied using eight arbitrary decamer oligonucleotides as primers. Species-specific RAPD fragments enabled reliable separation of the taxa studied. Generally, 1-3 fragments specific for P. percae and 1-4 P. exiguus-specific fragments were detected using individual primers. Intraspecific differences in P. percae depended on the primer used. The profiles generated by the primers OPA 04 and OPA 12 showed an intraspecific variation, whereas six other primers tested revealed indistinguishable banding patterns. On the other hand, intraspecific variability of P. exiguus, detected among four geographic isolates, was evident using all primers. Additionally, the utilization of two species-specific RAPD markers as effective probes was demonstrated. Distinct differences between P. exiguus and P. percae were revealed using each of the restriction enzyme/probe combinations.