C. Arme

Ultrastructural studies on the cellular response of fish hosts following experimental infection with the plerocercoid of Ligula intestinalis (Cestoda: Pseudophyllidea)

With the exception of gudgeon ( Gobio gobio ) infection of cyprinid fish with the plerocercoid of Ligula intestinalis is associated with a host-tissue response. The nature and specificity of this response has been investigated using transplantation techniques. In roach there is an intense cellular response to implanted Sepharose, Spurrs resin and L. intestinalis , irrespective of donor host species. However, tegument damage only occurs in gudgeon- Ligula and cultured ro&ch- Ligula which has been exposed to gudgeon-plasma. L1 and L2 cell types predominate within the cellular response. Once the host leucocytes have breached the tegument, they migrate over the basal lamina and penetrate into the sub-tegumental region. In gudgeon an intense cellular attack occurs against Sepharose, Spurrs resin, ro&ch- Ligula and cultured gudgeon- Ligula which had been implanted directly or exposed to roach plasma. Tegument damage only occurs in the latter. In contrast, neither direct implantation of gudgeon- Ligula nor cultured roach- Ligula which has been exposed to gudgeon plasma evokes a cellular response. It is suggested that in these two instances, as in natural infections of gudgeon, protective host proteins may be absorbed onto the surface of the parasite.

Hymenolepis diminuta: effect of metacestodes on production and viability of eggs in the intermediate host, Tenebrio molitor

Abstract An investigation into various parameters of host fecundity has been undertaken to establish whether the reduction in vitellogenesis, associated with Hymenolepis diminuta infection, results in any reduction of host reproductive potential. Female Tenebrio molitor commenced egg laying 6–7 days postemergence. Although no difference was detected in the total number of eggs ovulated or oviposited by 30-day-old beetles maintained singly or in crowded conditions, infected beetles kept in very crowded conditions laid fewer eggs. The pattern of egg laying during the first 30 days was found to differ with infection, the second peak (on day 18) being delayed by 4 days. Egg volumes were significantly reduced in infected 15- and 30-day-old virgins and eggs retained by 15-day-old virgins contained less protein. Parasitization was also found adversely to affect egg viability.

Tenebrio molitor (Coleoptera): effect of metacestodes of Hymenolepis diminuta (Cestoda) on haemolymph amino acids

Haemolymph free amino acids (HFAAs) in adult Tenebrio molitor varied in concentration with beetle age. Between 9 and 30 days post-emergence the concentration range was 34–94 m M with a peak occurring in 15-day-old insects. Much of this age-related variation was due to changes in the concentration of a single amino acid, proline. An analysis of concentrations of individual HFAAs in 15-day-old beetles, following infection with metacestodes of Hymenolepis diminuta , revealed that changes in female insects are more marked than those occurring in males. In the former, changes occurred in the concentration of 9 amino acids (isoleucine, leucine, arginine, serine, threonine, tyrosine, phenylalanine, proline and alanine/citrulline) whereas in the latter only 4 amino acids were affected (threonine, glycine, histidine and arginine). It is suggested that H. diminuta may interact with the endocrine system of its beetle host.

Ligula intestinalis : interactions with the pituitary-gonadal axis of its fish host

I was delighted to be able to join with so many friends and colleagues, in writing this short paper to mark the retirement of Donald Lee. There are many outstanding milestones in Donalds career. However, I thought that I could perhaps draw special attention to his long and distinguished association with the British Society for Parasitology (BSP), and the journal, Parasitology . He was President of the BSP between 1978 and 1980 and, in recognition of his service to the Society and contributions to the discipline of parasitology, was elected an Honorary Member in 1980. Donald has also had a long association with Parasitology , as a member of the Editorial Board and as a frequent contributor. His first paper in the journal was published in 1958; it described the occurrence of Syngamus sp. in a fieldfare ( Turdus pilaris ) that had been accidentally killed. At the time of writing, his most recent publication, but I suspect not his last, was a biochemical study on proteins produced by Nippostrongylus brasiliensis, Nematodims battus and Ascaridia galli (Foster & Lee, 1996). Of course, Donald has published in many other journals and authored several books. However, if one considers only those papers published in Parasitology , they provide a record of intellectual vigour and curiosity that has remained undiminished throughout his career.

Pathophysiology of Hymenolepis diminuta infections in Tenebrio molitor: effect of parasitism on haemolymph proteins

The effects of metacestodes of Hymenolepis diminuta on haemolymph proteins of Tenebrio molitor are restricted to female hosts. In beetles aged 15 days post-emergence, and harbouring 12-day-old metacestodes, haemolymph concentration is 46·7% higher than in non-infected animals and similar effects are found in longer standing infections. Electrophoresis of haemolymph revealed the presence of 13 bands. Densitometric analysis showed that only band 2/3 was significantly elevated in infected hosts although band 7/8 also showed an increase. These bands were also present in egg homogenates and are thought to be vitellogenins. It is therefore proposed that the excess protein found in infected beetles is a female-specific protein resulting from an interaction between the parasite and the host endocrine system.

Hymenolepis diminuta : influence of metacestodes on synthesis and secretion of fat body protein and its ovarian sequestration in the intermediate host, Tenebrio molitor

Female Tenebrio molitor infected with metacestodes of Hymenolepis diminuta exhibit elevated concentrations of female-specific proteins in their haemolymph and the origin of these has been investigated. Following a 4 h in vitro incubation with [14C]leucine, fat bodies from non-infected females secreted 13 times more protein than those from females 12 days post-infection. A comparison of the uptake in vivo of radio-isotope labelled amino acids by ovaries from non-infected and infected beetles of various ages revealed no differences; however, a 51.5% decrease in protein sequestration was detected in females 12 days post-infection. Electrophoresis of homogenates of radio-isotope labelled ovaries demonstrated that the majority of label was associated with vitellin sub-units. It is suggested that the decrease in vitellogenin sequestration associated with infection results in an increase in the haemolymph concentration of these proteins despite a concomitant reduction in their secretion by fat bodies. Both fat body synthesis and ovarian sequestration are under juvenile hormone control and it is proposed that metacestodes of H. diminuta may cause a reduction in the concentration of this hormone in the intermediate host.

Hymenolepis diminuta: effect of infection upon the patency of the follicular epithelium in the intermediate host, Tenebrio molitor

Abstract Several features of the pathophysiological response of Tenebrio molitor infected with metacestodes of the tapeworm Hymenolepis diminuta indicate that juvenile hormone titer may be reduced as a result of infection. In order to investigate this further a juvenile hormone-controlled event, namely, the development of patency in the follicular epithelial cells, has been examined in noninfected and infected beetles of various ages. A patency index (PI) was devised for terminal follicles. PI values were reduced in the follicles of infected 9-day-old mated and virgin females which were undergoing mid and late vitellogenesis. The presence of metacestodes was also associated with a reduction in the degree of patency in 9-, 15-, and 30-day-old mated and 9-day-old virgin beetles. A significant increase in resorption of terminal oocytes occurred in 15-day-old virgins and in 30-day-old mated females. These data are consistent with the hypothesis that juvenile hormone concentration is reduced in infected insects.

Echinococcus granulosus equinus: variation in the germinal layer of murine hydatids and evidence of autophagy.

The germinal layer of sterile 9-month-old murine peritoneal cysts of Echinococcus granulosus equinus shows interrelated variation in depth, tissue integrity, metabolic reserves and the number of autophagic lamellar bodies present. These features are similar in large and medium-sized cysts from the same host, whether occurring singly or within cyst masses. Deep germinal layers (greater than 16 micron) are lipid- and glycogen-rich and possess numerous autophagic vacuoles with 6 nm period lamellar stacks asymmetrically disposed peripherally; shallow layers (less than 12 micron), with indications of degeneration, have depleted metabolic reserves and fewer lamellar bodies. These bodies are formed by smooth endoplasmic reticulum encirclement of small glycogen masses followed by further sequestration, and eventually definition of glycogen particles may be lost. Autophagy of mitochondria and cytoplasmic vesicles also occurs. The presence of lysosomal enzymes within the layer suggests autolysosomal compartmentalization of excess substrate and effete material. Mucopolysaccharide bodies, containing material similar to that exocytosed to form the laminated layer matrix, occur and are formed from fusion and autophagy of Golgi-derived vesicles. These bodies may also develop peripheral 6 nm period lamellar stacks, but of limited depth. Mucopolysaccharide bodies are the dominant feature of the germinal layer of very small cyst-mass cysts in which laminated layer production is considered to be arrested. They thus represent a repository for the unreleased mucopolysaccharide material.

Proliferation of pronephric lymphocytes of carp, Cyprinus carpio induced by extracts of Bothriocephalus acheilognathi

The interaction between Bothriocephalus acheilognathi Yamaguti, 1934 (Cestoda) and pronephric lymphocytes of carp, Cyprinus carpio L. was studied by examining proliferation of lymphocytes isolated from both naïve fish and fish injected intraperitoneally with cestode extract. Lymphocytes from naïve hosts were stimulated to proliferate in the presence of the extract depending upon the extract protein concentrations; lower concentrations (0.01-0.05 microgram/ml) induced the greatest response, and immunosuppression occurred at higher concentrations. Significant differences were noted in fish that received intraperitoneal injections of parasite extracts. Five days post-injection, lymphocyte proliferation was significantly greater in these individuals compared with sham injected or untreated controls. This difference was reduced at 10 days post-injection, although the response was dependent on the concentration of the parasite extract. The possible significance of the observed stimulation/suppression of lymphocyte activity to establishment of the parasite in the wild is discussed.

Observations on the microtriches and stages in their development and emergence in Caryophyllaeus laticeps (Caryophyllidea: Cestoda)

Abstract Richards K.S. and Arme C. 1981. Observations on the microtriches and stages in their development and emergence in Caryophyllaeus laticeps (Caryophyllidea: Cestoda). International Journal for Parasitology 11 : 369–375. Fully developed microtriches of the posterior two-thirds of the body consist of three regions. The long, proximal shaft is ovoid in transverse section and has a peripheral electron-dense support and a central lucent core. The tapering, recurved, electron-dense spine lacks substructure and is ovoid at its base. The membrane-bound distal extension is in continuity with the proximal regions and its cytoplasm is coarsely granular. It is frequently observed in a reflexed position lying parallel to the shaft. In developing microtriches the ovoid spine lies parallel to the worm surface whereas the shaft support and core are perpendicular to the syncytial surface; the distal extension is not present. During microthrix emergence the spine comes to lie in an erect position above the apical membrane, then the shaft support and core begin to emerge and the distal extension develops.