Total RNA was extracted from packed infective larvae of Trichinella spiralis by centrifugation through a 5·7 M caesium chloride cushion. Polyadenylated messenger RNA was separated from total RNA in an oligothymidylic acid-cellulose gel column. The in vitro translation of the mRNA, isolated from infective larvae of T. spiralis, was carried out using the rabbit reticulocyte cell-free translation system. Incorporation of 35S-methionine into trichloracetic acid precipitates in the lysate containing mRNA was 5 times greater than that in control. The translation products were analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) followed by autoradiography. Many polypeptides with molecular weights of less than 100 000 were synthesized in the lysate. A T. spiralis positive mouse serum was mixed with translation products to form antigen-antibody complexes, which were then absorbed by Staphylococcus aureus Cowan 1 strain and analysed by autoradiography of SDS-PAGE. An antigenic polypeptide with a molecular weight of 48 000 was demonstrated to react specifically with IgG antibody in T. spiralis positive mouse serum. T. spiralis larvae were cultured in methionine-free medium containing 35S-methionine, and antigenic polypeptides in somatic extracts and ES products were compared with those in translation products by autoradiography of SDS-PAGE. Several polypeptides in ES products and somatic extracts reacted specifically with IgG anitbodies in positive serum. Especially the polypeptide with a molecular weight of 48 000 in ES products strongly reacted with IgG antibody in positive serum.

Mice presensitized with SEA and subsequently injected with S. japonicum eggs into their lungs or liver developed pathology similar to that found in infected mice and were consequently resistant to challenge (average 33% and 53%, respectively). However, soluble egg antigens were also capable of inducing low levels of resistance in mice (average 22·5%), but intact eggs alone injected into the lungs, liver or subcutance tissues were not. Thus, prior sensitization to ‘marginally’ protective soluble egg antigens is necessary for egg induced resistance.

Mechanisms of protective immunity to larvae of Brugia pahangi were studied in congenitally athymic nude C3H/HeN mice and their syngeneic heterozygous littermates. An average 11% if subcutaneous larval inocula was recovered from control nudes 28 days after inoculation. No worms were recovered from nude recipients of viable splenic Thy 1·2+ T lymphocytes from heterozygotes which had killed a priming does of B. pahangi larvae. Primed T lymphocytes, depleted of either Lyt 1·1+of Lyt 2·1+cells or incubated with anti-Thy 1.2 monoclonal antibody and complement, failed to protect nude mic against a larval challenge. Nor were primed B lymphocytes depleted by Thy 1·2+T cell contaminants protective. Treatment with cyclosporin A (CsA) did not increase the numbers of worms recovered from heterozygotes nor did CsA treatment of heterozygous cell donor abolish the ability of primed Thy 1·2+T lymphocytes to transfer protection to nude mice. IgG but not IgM antibody titres to B. pahangi antigens were depressed in all CsA-treated mice. CsA treatment of nude mice had no direct effect upon development of B. pahagi larvae. These results show that ptotective immunity to larvae of B. pahangi in mice depends upon small numbers of Thy 1·2+T cells which are CsA-resistant.

Heterophyes heterophyes is reported for the first time from the snail host Pirenella conica in Greece. H. aequalis and H. dispar are reported for the first time from Greece and from Europe. The results presented, together with the available data on necropsies of dogs and cats, human infections and the biotope preference of the snail, suggest that Greece is an important focus of infection in Europe.

Heterophyes heterophyes, H. aequalis and H. dispar showed distinct zonation in the small intestine of different definitive hoste. The flukes were found in their appropriate zone within four to six hours after infection. It appeared that their position shifted posteriorly during their life and that the shift proceeded more rapidly in unsuitable hosts. Hisgological sections revealed that the flukes are not deeply embedded in the host's mucosa.

Chromosomes of Nigerian Onchocerca volvulus were compared with those of Guatemalan O. volvulus. Both parasites had basically the same chromosomal construct (2n=8, XY type). Autosomes consisted of a pair of large and two smaller pairs. Sex chromosomes were made up of medium sized X chromosome and very small Y chromosome. It was not possible to infer the position of the centromeres.

Living, intact protoscoleces of the British horse and sheep strains of Echinococcus granulosus were subjected to surface radioiodination procedures using 125I and Iodogen and 125I-Bolton Hunter reagent. Subsequent combined electron microscopy and autoradiography revealed specific surface membrane labelling with the Iodogen procedure, but significant tegumental labelling with the Bolton-Hunter reagent. The two parasite strains yielded different profiles of electrophoretically separated labelled proteins; the Iodogen method, not surprisingly, resulted in a less complex pattern of labelled polypeptides than the Bolton and Hunter reagent.

The in vivo efficacy of monensin against Fasciola hepatica was determined in the albino rat. The results were variable, with monensin generally showing greater activity against juvenile (two-week-old) than adult (12-week-old) fludes. Significant (p<0·005) reductions in worm burdens were obtained only following treatment of adult flukes with 2×10 mg/kg monensin (52·9% efficacy), and of juvenile flukes with 1×10 mg/kg (42·4% efficacy) and 2×10 mg/kg (56·23% efficacy). Monensin administered in the diet (200 ppm) had a negligible effect on juvenile and adult fluke burdens. Prophylactic treatment of rats with monensin (100 ppm) produced a 45·5% efficacy, but this was not statistically significant. At doses of 1×5 mg/kg and 2×2·5 mg/kg, monensin had little effect on egg output by F. hepatica. No clear relationship was established between egg output and worm burden, and so faecal egg counting was not a reliable indicator of fluke burdens in the rat.

The formation of the egg mass in the ootype, containing the oocyte, vitelline cells, numerous spermatozoa and Mehlis’ gland secretion marks the beginning of eggshell formation. Mehlis’ gland cells pour their lipoprotein secretion into the ootype; this secretion forms a thin template around the egg mass and upon this template the shell globules are deposited. Eggshell formation begins in the proximal uterus and is completed in the middle uterus. The eggshells are devoid of phenols and phenolase indicating that hardening is not by quinone tanning. The eggshells contain keratin and are stabilized by disulphide linkages.

In field experiments, conducted on parasite-free grass plots in two consecutive summers, artificially prepared cow pats containing Cooperia oncophora eggs were inoculated with the nematode-trapping fungus Arthrobotrys oligospora. Numbers of infective C. oncophora larvae isolated from the pats as well as from the surrounding herbage were subject to an approximately teh-fold reduction as compared with numbers in fungus-free pats and herbage surrounding these. This reduction was undoubtedly a result of entrapment of the parasite larvae within the faecal pats.

The diploid chromosome number of Protostrongylus rufescens is 2n=11 for males and 2n=12 for females. So, the sex determinism mechanism is XO/XX. The study of the genetic behaviour of this species has been made. In diakinesis stage the bivalents show typical tetrads with cross, Ø, and lineal configurations. The division of the sexual chromosome is prereductional for the first meiotic division.

Prevalence and intensity of helminth parasites are described for a sample of 102 Jamaican anole lizards representing 6 species (Anolis lineatopus lineatopus, A. I. neckeri, A. grahami, A. valencienni, A.opalinus, A. sagrei, A. garmani). Fifty nine per cent of lizards were infected with 5 species of nematodes, 16% with one acanthocephalan, 7% with two digeneans, and 4% with a single cestode species. Infection intensity was generally low (intensity range 1–5) although two species of nematode occurred in very large numbers (intensity range 1–436). Helminth prevalence patterns and species composition reflected differences in anole habitats rather than ecomorphs, and were uncorrelated with the genetic relatedness of indigenous versus introduced anole species.

Ancylostoma ceylanicum and Nippostrongylus brasiliensis decarboxylated most of the amino acids examined, but only a few at signficant rates. The former nematode in general possessed higher activites. Striking differences between the two parasites were, however, noticed regarding the metabolism of some of the amino acids. For instance, while alanine followed by asparate produced highest amounts of 14CO2in the presence of A. ceylanicum, proline exhibited maximum decarboxlation in case of N. brasiliensis. Tyrosine, on the other hand, did not libreate detectable CO2with either parasite. Likewise, although large number of amino acids underwent transmination with 2-oxoglutarate, only some of them elicited appreciable activity for any two parasites.

Cercarial production related to miracidial dose variation with Schistosoma bovis strains from Sudan and Spain in Bulinus truncatus from Tunisia was studied. Results showed that an increase in the miracidial dose proposed to the host-mollusc (1 and 5 miracidia) gave rise to a decrease in cercarial productivity of Sudanese S. bovis and to an increase for Spanish s. bovis. It is concluded that this response difference tothe miracidial dose variation depends on genetic characters peculiar to the parasite strain and represents a new aspect of genetic variability of schistosome populations.