Experimental Trichinella spiralis infection in sheep.

During susceptibility studies of non-specific hosts, three merino sheep were infected with 3000, 5000 or 7000 Trichinella spiralis larvae by gavage. Clinical, physiological and serological parameters were assessed during the experiment. On the 152nd day p.i., animals were necropsied and, using artificial digestion methods, numbers of Trichinella larvae in muscle tissues were determined. The most infected parts were masseters with 3122 larvae g-1 muscle, 5526 larvae g-1 muscle and 4058 larvae g-1 muscle and diaphragms with 2778 larvae g-1 muscle, 2725 larvae g-1 muscle and 2320 larvae g-1 muscle, for the 3000, 5000 and 7000 infection levels, respectively. A positive correlation between infective rate and circulating antibodies was observed using ELISA and latex agglutination (LA) test methods. Trichinella larvae from sheep applied by gavage to ICR mice developed to the muscle stage. No significant changes were found in the clinical and physiological parameters of infected animals. Our results confirm the high susceptibility of merino sheep to T. spiralis infection.

Some enzymes of carbohydrate metabolism in Mesocestoides corti and Heterakis spumosa.

The activities of selected enzymes of carbohydrate metabolism were measured in tetrathyridia of Mesocestoides corti and in adult females and males of Heterakis spumosa. When the species were compared, only lactate dehydrogenase and phosphoenolpyruvate carboxykinase activities were considerably higher in M. corti. Activities of other enzymes were higher in H. spumosa, with malate dehydrogenase activity being considerably so. In H. spumosa, enzyme activity was higher, and succinate dehydrogenase markedly so in males, when compared with females. Tetrathyridia aged 170 and 210 days show relatively stable malate and lactate dehydrogenase activities, and mice of ICR and BALB/c strains are suitable for the maintenance of tetrathyridia.

Chitin synthesis in zygotes of Ascaris suum.

In Ascaris suum chitin is formed in the zygote immediately after oocyte fertilization, and its synthesis is completed in the eggs from the distal half of the uterus. Incorporation of radiocarbon [14C] glucose into chitin of the eggshell was 40-fold higher than incorporation of [14C] glucosamine. The same rank order also holds for the incorporation of label from these isotopes into the glycogen of the ovaries. A large part of the radiolabel was incorporated first into oocyte glycogen and only after fertilization was it incorporated into eggshell chitin. Actinomycin D inhibited chitin synthesis in the eggs from the distal half of the uterus and it significantly reduced incorporation of radiocarbon from glucose into chitin.

Properties and localization of chitin synthase in Ascaris suum eggs.

Investigations were carried out into the properties and localization of chitin synthase (EC 2.4.1.16) in connection with the formation of Ascaris suum egg-shells. The chitin synthase of eggs exhibited properties very similar to those found in other chitin-synthesizing organisms. It was stimulated by the presence of ATP, GlcNAc and Mg2+ with maximal activity at pH 7.0. In the phase of active chitin synthesis, during formation of the primary shell layers, chitin synthase was bound to the structures of the eggs. On completion of chitin synthesis in the eggs, the amount of the enzyme increased in the soluble fraction. Two forms of chitin synthase have been found in the eggs, namely an inactive (zymogenic) and an active form. Transformation of these two enzyme forms represents a key mechanism in the regulation of chitin synthesis in A. suum eggs.

Some precursors of glycogen in Ascaris suum females.

Intensity of incorporation of the labelled carbon from glucose, glucosamine and leucine into the glycogen of somatic cells and reproductive organs of Ascaris suum females has been studied. Glucose was most intensively incorporated into the growing oocytes and into the uterine epithelial cells, whereas its incorporation into muscle glycogen was found to result in lowest rates. Radiocarbons from glucosamine and leucine were incorporated into tissue glycogen of female worms much less than glucose. Incorporation of isotopes into glycogen of the eggs depended on the formation of their primary shells. The ways of incorporation of isotopes into glycogen of the eggs after formation of all the shell layers are discussed.

[Influence of Ascaridia-galli invasion on amino acid, protein and aminotransferase (GOP, GTP) levels and activities in chickens]. / Vplyv invázie helmintmi Ascaridia galli na hladinu aminokyselín, bielkovín a aktivity aminotransferáz (GOT, GPT) u kurciat.

A negative influence of the helminths Ascaridia galli on the level of free plasma amino acids and aspartate and alanine aminotransferase activities was demonstrated in the host chick serum. Despite the above negative influence single experimental Ascaridia galli invasion failed to influence the serum protein level or weight increments in chicks. At low invasion intensity the experimental chicks were able to compensate for the pathogenic effect of the helminth Ascaridia galli, manifested by decreased amino acid and aminotransferase activity levels, provided that they were given a full-value and the chicks were kept under suitable zoohygienical conditions.