Hymenolepis diminuta: an electron microscope study of ion absorption

Ten-day-old Hymenolepis diminuta were incubated in media containing either the divalent cations barium or lead, or the divalent anions sulfate or ferrocyanide. Mitochondria of the tegument, but of no other tissue with the time scale used, accumulated all these ions in conspicuous amounts.By visual inspection mitochondria appeared to accumulate ions in the following order of preference, lead > sulfate > barium > ferrocyanide. These results have been interpreted with reference to Lehninger's theory of ion accumulation in vertebrate mitochondria, in that it is suggested the results depend on the presence or absence of permeant cations. From the viewpoint of ion accumulation, the mitochondria of Hymenolepis diminuta appear to be similar to vertebrate mitochondria.Ion deposits also occurred attached to apical and basal plasma membranes of the tegument and to the membranes of the multitubular complex. Reactions at these sites appear to be due to the properties of their associated glycocalyx. The presence of deposits in and around multitubular complexes also supports the previous suggestion that this structure may play a role in ion or water transport in this tapeworm. The deposits which occurred in the interstitial material appear to be the result of a reaction between acidic groups present in the matrix material of this connective tissue and cations in the incubating and fixing solutions.     

Hymenolepis diminuta: mitochondrial transhydrogenase as an additional site for anaerobic phosphorylation

Employing adult Hymenolepis diminuta SMP and exogenous pyridine nucleotide-generating systems, reduced pyridine nucleotide-dependent net 32P incorporation into ATP was examined. NADH supported rotenone-sensitive 32P incorporation and this rate increased markedly with fumarate addition, in keeping with an active fumarate reductase. Interestingly, corresponding evaluations with NADPH did not result in detectable phosphorylation in the absence or presence of fumarate. However, with NAD addition, but without NAD generation, active NADPH-dependent phosphorylation occurred, thereby demonstrating mitochondrial transhydrogenase involvement, and 32P incorporation increased significantly with fumarate addition. More importantly, in the presence of rotenone and both NADPH and NAD generation, significant net 32P incorporation was noted, but was undetectable in the presence of DCCD or protonophores (e.g., niclosamide). Without NAD generation, minimal phosphorylation occurred. These data demonstrate that with ongoing NADPH and NAD generation, the H. diminuta, proton-translocating, mitochondrial transhydrogenase can serve as an additional anaerobic phosphorylation site. A model is presented.     

Pancreatic secretion is the migratory cue for Hymenolepis diminuta in rat small intestine

Pylorus and bile-duct restrictions did not prevent the anteriad migration of Hymenolepis diminuta in rat small intestine after food feeding. However, migration was inhibited when the common bile-duct was occluded. The results indicate that pancreatic secretion is the migratory cue for Hymenolepis diminuta in rats.     

Diurnal periodicity of uridine uptake by Hymenolepis diminuta

A diurnal pattern in the uptake of uridine was displayed by the rat cestode Hymenolepis diminuta. No periodicity in the uptake of uracil was observed over a 48-hr period. A high level of uridine uptake occurred at 6 PM. when 10-day-old worms were in a posterior location in the intestine of rats maintained on a 6 PM.-6 AM. dark cycle-feeding regime, while low levels of uptake were correlated with an anteriad location at 6 AM. The lowest levels of uridine uptake were recorded at noon. Coincubation with thymine caused a stimulation of uridine uptake at midnight, 6 AM., and noon when uridine's transport rate in the absence of thymine was low. Stimulation was not demonstrable when uridine's transport rate was at its highest at 6 PM. Preincubation with uridine did not alter the diurnal uridine uptake pattern. This diurnal phenomenon is an important consideration essential to future studies on transport in parasitic and other organisms.     

Hymenolepis diminuta: immunogenicity of the strobilate worm

Mice were immunized against challenge with Hymenolepis diminuta by feeding cysticercoids or by surgically implanting into the duodenum strobilate worms of different ages. Young worms stimulate stronger immunity than older ones, although the latter presents the host with a greater amount of strobilar tissue per unit time. An increase in the number of immunizing worms is associated with an increase in the level of protection. It is concluded that the development of functional immunity against H. diminuta in mice has both quantitative and qualitative antigenic requirements; it is influenced by worm age and is independent of worm mass.     

Expression of MEL-14 antigen is not an absolute requirement for dissemination to lymph nodes after adoptive transfer of murine T lymphocyte clones

The inability of established antigen-specific murine T lymphocyte clones to recirculate well in vivo has been attributed to loss of the surface glycoprotein gp90MEL-14, which is important for specific adherence to post-capillary high endothelial venules in peripheral lymph nodes (LN). Defective recirculation of clones may contribute to inefficient adoptive immunotherapy when compared with fresh immune spleen or LN populations. To optimize models of adoptive immunotherapy, we sought to improve recirculation of Thy-1.2+, L3T4+ clones by inducing reexpression of MEL-14 antigen (gp90MEL-14). Clones were analyzed after treatment with differentiating agents, incubation in the presence or absence of recombinant interleukin 2 (rIL 2), coincubation in vitro with nonirradiated Thy-1.1 LN or thymus cells, or adoptive transfer into Thy-1.1 hosts. We were unable to demonstrate induction of gp90MEL-14 in any case. However, although clones remained MEL-14 negative, they were able to disseminate widely after subcutaneous adoptive transfer in the presence of clone-specific antigen and rIL 2 into Thy-1.1 mice pretreated with cyclophosphamide. Withdrawal of exogenous rIL 2 was associated with rapid disappearance of clones from all sites. We conclude that murine T cell clones undergo a step in terminal differentiation that precludes surface expression of gp90MEL-14 and that these clones would be unlikely to provide a source of long-lived recirculating memory T lymphocytes. However, under appropriate circumstances it is possible for antigen-specific clones to disseminate widely among host LN and mediate short-term immune responses.     

Complement-mediated lysis in vitro of newly excysted tapeworms: Hymenolepis diminuta, Hymenolepis microstoma, Hymenolepis nana and Hymenolepis citelli

Bøgh H., Christensen J.P.B. and Andreassen J. 1986. Complement-mediated lysis in vitro of newly excysted tapeworms: Hymenolepis diminuta, Hymenolepis microstoma, Hymenolepis nana and Hymenolepis citelii. International Journal for Parasitology16: 157–161. Newly excysted worms of Hymenolepis diminuta were lysed in 50% normal serum from all 13 animal species tested, including man. Since H. diminuta was neither lysed in complement inactivated serum—by heat or adding EDTA, LPS or CVF—nor in C5-deficient mouse serum, it is concluded that the lysis was associated with the complement cascade. It is shown that H. diminuta can activate the complement system via both the classical and alternative pathway. Furthermore, it is indicated that the lysis is independent of serum antibodies. Hymenolepis nana and H. citelli were also lysed in all normal sera tested, eight and six respectively, while newly excysted worms of H. microstoma were lysed in normal sera from 10 mammals and birds, but not in sera from its hosts, the mouse, rat and golden hamster. This indicates that the complement system of these three species differs from that of the other species tested in such a way that H. microstoma is able to avoid lysis in these sera.