K. Sylvia Richards

The occurrence and localisation of heavy metals and glycogen in the earthwormsLumbricus rubellus andDendrobaena rubida from a heavy metal site

SummaryThe lead content of whole earthworms, highest in contaminated site specimens, was significantly higher inDendrobaena rubida thanLubricus rubellus and a species difference in zinc was also recorded. Selective feeding and differential absorption are discounted and a species difference in maximum tolerance to body lead is suggested. Copper was low in all specimens. Chloragocytes and intestinal tissue showed significantly higher lead levels in contaminated earthworms than in control material. Ultrastructurally, chlorgocytes from contaminated earthworms showed electron dense flecks associated with the chroragosome peripheries and within the debis vesicles. Very fine flecks occurred in the nuclei, but mitochondria and Golgi were indistinguishable from control material. Preliminary X-ray microanalysis of contaminated chloragocytes revealed lead and phosphorus. The deposits within the chloragocytes might represent unbound lead precipitated by phosphate buffer; flecks being absent from contaminated, citrate buffered material and from control material. The chloragosomes are proposed as possible sites for sequestered lead.Chloragocyte and intestinal glycogen levels were significantly higher in control material where the chloragocyte cytoplasm was rich in α-glycogen rosettes, these being absent from lead contaminated cells. The glycogen-lead correlation suggests that the metabolism of contaminated chloragocytes is directed towards lead sequestration, though differing nutritional states cannot be ignored.

Glycogen-lead relationship in the earthworm Dendrobaena rubida from a heavy metal site

SummaryControl individuals contained no lead in the chloragocytes but high α-glycogen rosette reserves. Starvation of contaminated earthworms for 4d caused a lead loss and the chloragocytes possessed fewer debris vesicles than those of unstarved worms, suggesting that the debris vesicles may be the route for at least some of the lead loss. No glycogen deposits were observed in the chloragocytes of starved or unstarved earthworms from contaminated soil. Maintenance of contaminated earthworms in potting compost caused lead losses similar to those sustained by starvation, but the chloragocyte cytoplasm possessed β-glycogen reserves. Specimens maintained in lead-spiked potting compost showed lead levels similar to those of earthworms taken directly from contaminated soil. No β-glycogen accumulations were observed under this enriched regime.Although the possible interference of lead in carbohydrate metabolism is discussed, the results do not wholly support metabolic inhibition by lead. It is hypothesised that lead sequestration is energy-demanding and that in the absence of an energy-rich diet glycogen stores fail to accumulate. In the presence of an organic-rich medium, elevated lead levels preclude glycogen formation, because of the high sequestration-demand, but at lower lead levels β-glycogen deposits occur if a high organic diet is available.

Spermiogenesis in the enchytraeid Lumbricillus rivalis (Oligochaeta: Annelida)

The mature spermatozoon of Lumbricillus rivalis consists of a short, straight acrosomal complex, an elongated nucleus with a raised helical flange, four mitochondria twisted together in a short cylinder, and a conventional flagellum containing glycogen granules. The events of spermiogenesis are broadly similar to those reported for other clitellate annelids, and support the hypothesis that the microtubules of the manchet are a necessary, but not a sufficient, cause of chromatin condensation in some animal groups. However, there are sufficient differences in detail pertaining to the relation of the manchet to the final spiral shaping of the organelles to suggest that this shaping is determined by endonuclear factors rather than by the manchet. The functional significance of the helical form of the spermatozoon is considered, and the role of microtubules in spermiogenesis of annelids and other animal groups is discussed in the light of current hypotheses.

In vitro development of hydatid cysts from posterior bladders and ruptured brood capsules of equine Echinococcus granulosus.

A variety of morphological forms developed during monophasic culture of ruptured brood capsules of equine Echinococcus granulosus. Attached to some protoscoleces were small posterior bladders, with a surface ultrastructure of truncated microtriches, and these never developed a laminated layer. In contrast, small free vesicles of similar size and ultrastructure, but devoid of an attached protoscolex, produced a layer by 20-30 days. The surface ultrastructure of both these forms is similar to that of the protoscolex attachment stalk and the brood capsule lining, and posterior bladders and small free vesicles are considered to be derived from portions of the stalk +/- part of the brood capsule lining retained at protoscolex release. Also present were large vesicles interpreted from their size and surface anatomy as ruptured, everted brood capsules. When devoid of attached protosoleces these formed cysts each with a laminated layer, whereas similar vesicles with several attached protoscoleces did not develop a layer, or only very occasionally after 70 or more days. In contrast, a few large vesicles with a single attached protoscolex produced a laminated layer. The possibility that protoscolex attachment to stalk remnants or brood capsules inhibits the cystic development of these structures is discussed.

Echinococcus granulosus: in vitro effect of monensin on the tegument of the protoscolex.

Protoscoleces of Echinococcus granulosus were incubated in a 10 microM solution of monensin and their viability and the ultrastructure of their tegument were monitored over a 36 h period. The earliest effects of the ionophore, apparent within 15 min, involved a degree of cisternal swelling of the tegumentary Golgi complexes. Swelling became more pronounced with time and cytons eventually contained numerous large electron-lucent vesicles. Residual bodies indicative of autophagy were observed in the cytons and distal cytoplasm from 1 h onwards. All movement of protoscoleces ceased after 1 h and the surface of the soma subsequently became folded, possibly suggesting spastic paralysis. Later, vacuoles and large cytoplasmic blebs were observed in the distal cytoplasm and viability dropped rapidly after 12 h. All protoscoleces were dead at 36 h. The potential of monensin as an in vivo protoscolicidal agent is discussed.

Development of the tegument ofechinococcus granulosus (Cestoda) protoscoleces during cystic diffentiation in vivo

During the first 4 days following infection, early tegumentary changes are confined to the protoscolex soma ofEchinococcus granulosus, the thick glycocalyx being lost and the blunt elevations, flattened. The Golgi complexes within the tegumentary cytons produce T2 vesicles that increase in number in the tegument from days 4 to 12, whereas T1 vesicles decline. Spineless, truncated microtriches develop at the somal surface, and the laminated layer starts to form around the developing cyst from days 20–40 onwards. T2 vesicles do not appear to be involved in its formation and decline in number. Two additional vesicle types participate in the production of the laminated layer: T4 vesciles contribute to the carbohydrate matrix, and ‘G’ vesicles form granular accumulations. Cystic differentiation is completed after 2–3 months, when the spined microtriches and rostellar hooks of the scolex are shed into the laminated layer and replaced by truncated microtriches. These ultrastructural changes are discussed with respect to parasite survival.

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.

Spermatozoal phagocytosis by the spermathecae of Dendrobaena subrubicunda and other lumbricids (Oligochaeta, Annelida)

Spermatozoal phagocytosis by pseudopodial-like, avillous portions of the spermathecal epithelial cells of Dendrobaena subrubicunda is described at the ultrastructural level. The resultant phagosomes are digested by an aryl sulphatase-rich lysosomal system. Sperm ingestion also occurred in Allolobophora caliginosa, A. chlorotica, A. longa and Lumbricus rubellus. All specimens were collected in late autumn-early winter, and phagocytosis is discussed in relation to the removal of ageing and/or aberrant sperm during the months when cocoon-production is minimal. In the parthenogens A. rosea and Octolasion cyaneum and in the amphimictic Eisenia foetida, the spermathecal epithelium possessed a continuous microvillous brush border and the cytological features associated with phagocytosis were not observed. The apparently anomalous condition in E. foetida is discussed.

Transintegumentary uptake of amino acids by the lumbricid earthworm Eisenia foetida

Abstract 1. 1. Transintegumentary uptake of neutral, basic and acidic amino acids is demonstrated in vitro . Concentration ratios do not exceed equilibrium. 2. 2. Uptake consists of a diffusion and a mediated component. Susceptibility to metabolic inhibitors is shown and Q 10 values exceed 2. 3. 3. Reciprocal, competitive inhibition occurs between amino acids, but cycloleucine uptake is unaffected by the presence of basic or acidic amino acids or glucose. 4. 4. Neutral amino acid influx is not susceptible to Na + levels and is unaffected by ouabain. 5. 5. The uptake rate pattern is: neutral > basic > acidic amino acids.

Effect of Albendazole on Human Hydatid Cysts: An Ultrastructural Study

Five patients with hepatic (3), pelvic (1) or spinal (1) hydatid cysts received 10 mg/kg/d albendazole for 1–3 months prior to surgery. Daughter cysts were present in the spinal hydatid and in one patient with hepatic disease. Electron microscope examination of the cyst tissue of the pelvic and the 2 hepatic cysts lacking daughter cysts showed no evidence of germinal layer, and the protoscoleces were dead. The primary cyst of the hepatic hydatid with daughter cysts (1 month therapy) was also judged dead but some pieces of the daughter cyst germinal layer appeared normal and had unaffected protoscoleces. The daughter cyst tissue of the spinal hydatid (3 month therapy) appeared normal and the protoscoleces viable. In view of the undetermined viability of human hydatids before chemotherapy, treatment of longer than 1 month is advocated for hepatic cysts, particularly if daughter cysts are present, and longer therapy is indicated for spinal disease.