Effects of parasitism by the lung fluke, Haematoloechus medioplexus, on lung fatty acid and sterol composition in the bullfrog, Rana catesbiana

Intraspecific and interspecific pairing ofHaematoloechus medioplexus(Trematoda) andEchinostoma revolutum(Trematoda) adultsin vitro, and observations onH. medioplexuslipophilic excretory–secretory products

Intraspecific pairing ofHaematoloechus medioplexusandEchinostoma revolutumadults and interspecific pairing ofH. medioplexusandE. revoltumadults were studiedin vitroat 21 ± 1 °C and 30 ± 1 °C in Petri-dish cultures containing an agar substrate and a Locke's 1:1 solution overlay. Salinity and temperature tolerance tests showed that both species survived for 24 h in a Locke's 1:1 solution at 21 ± 1 °C and 30 ±1 °C. For behaviour studies, worms were placed 2 cm apart and then observed at various intervals from 5 min to 4 h.H. medioplexusandE. revolutumshowed significant intraspecific pairing at 30±1 °C, whereas onlyH. medioplexuspaired significantly at 21±1°C. Significant interspecific pairing ofH. medioplexusandE. revolutumoccurred at 21 ±1 °C and 30 ±1 °C. Thin-layer chromatographic analysis showed thatH. medioplexusadults released mainly free sterol, along with traces of triacylglycerols and free fatty acids into a non-nutrient medium.

Fatty acid composition of Echinostoma trivolvis (Trematoda) rediae and adults and of the digestive gland-gonad complex of Helisoma trivolvis (Gastropoda) infected with the intramolluscan stages of this echinostome

Gas-liquid chromatographic studies were done to determine the fatty acid composition of the digestive gland-gonad (DGG) complex of Helisoma trivolvis snails infected with the intramolluscan stages of Echinostoma trivolvis, of rediae freed from the DGG, of uninfected DGG, and of 41-day-old adult worms grown in golden hamsters. The DGG of infected snails showed significantly higher levels of stearic acid (18:0), hexatrienoic acid (16:3n-4), and docosahexanoic acid (22:6n-3) than that of uninfected snails. However, the DGG of uninfected snails showed significantly higher levels of 20:2 non-methylene-interrupted diene (NMID) and adrenic acid (22:4n-6) than that of infected snails. The profiles of other fatty acids were remarkably similar in both infected and uninfected snails. Adult worms showed significantly higher amounts of numerous saturated fatty acids and dienes as compared with the rediae. However, the rediae showed significantly higher amounts of certain monoenes and trienes as compared with the adults. Fatty acid differences between rediae and adults probably reflect differences in either the available lipid pools in the immediate host sites or the metabolic activity of each stage of this echinostome.

Histochemical and thin-layer chromatographic analyses of neutral lipids in various host sites infected with Leucochloridiomorpha constantiae (Trematoda)

Histochemical and thin-layer chromatographic (TLC) analyses were used to study the effects of trematode parasitism by Leucochloridiomorpha constantiae on sites occupied by this fluke. Oil Red O staining showed that the epithelium in infected sites, i.e., bursa of Fabricius of the domestic chicken, chorionic ectoderm of the chick embryo, and uterus of Campeloma decisum snails, was positive for neutral lipids. TLC showed that infection in the bursa caused an increase in free fatty acids and triglycerides in that organ; infection of the chick chorioallantois caused a decrease in free sterols and sterol esters in the membrane; the uterus of infected snails showed elevated free sterols.

Biochemical and physiological effects of metazoan endoparasites on their host species

1. The integrative nature of the parasite-host association was discussed, specifically with regard to the metabolic effects of parasitization as well as the physiological manifestation of infection in relation to the host's nutritional physiology. Endocrine interactions were also considered. 2. Relationships involving parasitic insects, including members of the orders Diptera, Hymenoptera and Strepsiptera, parasitic helminths, including members of the phyla Acanthocephala and Nematoda and the classes Cestoidea and Trematoda of the Platyhelminthes, as well as parasitic crustaceans in association with their invertebrate and/or vertebrate, intermediate, paratenic as well as definitive hosts were considered. 3. A broad conceptual or "topic" approach to understanding symbiotic relationships was emphasized. De-emphasis of descriptive categorization and the use of benefit/harm as criteria characterizing parasitic relationships was suggested. 4. The hypothetical concept of host regulation was briefly examined and the use of anthropometric descriptors such as "beneficial" and "harmonious" in parasitology discussed.