bluuebunny/crossref_metadata_2025 huggingface dataset:
Penetration of mammalian skin by the infective larva ofNippostrongylus brasiliensis
Authors: Lee D. L.
Published: June 2009

The behaviour of the third-stage larvae ofNippostrongylus brasiliensishas been studied on rat, mouse and human skin. Locomotion in thin films of moisture is by two-dimensional, undulatory propulsion on skin, and by three-dimensional, undulatory propulsion on hairs. In drops of water or in thick films of moisture locomotion is less efficient than in thin films. It is suggested that the thin film of moisture around larvae on the skin may become coated with a thin monolayer of lipid which could reduce evaporation from the surface of the nematode and from the film of moisture, thus extending the period before desiccation begins. Studies with the electron microscope have shown that the larvae move horizontally into the stratum corneum and later penetrate the epidermis and dermis by separating the constituent cells of these tissues. In the dermis there is dissolution of collagen around the larvae. It is suggested that this separation of cells and dissolution of collagen need not be brought about by enzyme action, as similar effects can be brought about by changes in pH or ionic composition of the bathing medium.
Changes in the ultrastructure of the caecum of chickens caused byTrichomonas gallinarum
Authors: Lee D. L.
Published: June 2009

The ultrastructure of the normal caecum of chickens and of chickens infected withTrichomonas gallinarumhas been investigated. In infected caeca some villi and crypts of LieberkÜhn appear normal whereas others show marked changes in structure of the epithelial cells. The most obvious changes are loss of microvilli and glycocalyx and an increase in number of vesicles which stain metachromatically with Azur II.T. gallinarumhas been detected between epithelial cells and in the lamina propria. Bacteria often, but not always, accompanied the protozoa in the tissues.
Chemical nature of monogenean sclerites. I. Stabilization of clamp-protein by formation of dityrosine
Authors: Ramalingam K.
Published: June 2009

The clamp sclerites ofPricea multaeand other higher monogeneans was fuchsin-positive in Mallory's and Masson's triple stain, and the staining was not affected by detanning agents, suggesting some form of stabilization in the protein. The sclerites were positive in Millon's, Morner's and Xanthoproteic tests for aromatic amino acids, but negative in tests for sulphydryl and disulphide groups. Quinone, phenol and phenol oxidase were absent. They stained with basic dyes such as toluidine blue and methylene blue in the pH range of 3·5–9·5, and also exhibited bluish fluorescence in u.v. light which was not affected by lipid solvents, indicating the presence of dityrosine and recalling the protein present in the ligament cuticle of insects. These features indicate that the clampprotein is stabilized by the formation of dityrosine. It is suggested that this protein may be responsible for the biological properties of the clamp sclerites. This mode of stabilization by tyrosyl residues of the protein, resulting in the formation of dityrosine, is the first record of its kind to be reported in platyhelminths.
Gregarine attachment organelles — structure and permeability of an interspecific cell junction
Authors: MacMillan W. G.
Published: June 2009

The junction between the gregarine trophozoiteNematocystis magnaSchmidt and an epithelial cell of its earthworm hostLumbricus terrestrisMuller consists of an extensive folding and meshing of the single trilaminar membrane bounding the host cell and the complex folded multilaminar limiting membrane of the trophozoite. They are separated by a structureless intercellular region of some 50 nm in width. Specialized communicating regions or permeable elements were not observed. Transport of a radioactive label across non-junctional and junctional membranes was demonstrated by using tritiated glucose. The attachment organelle of the trophozoite is shown to be capable of allowing metabolites to pass into the cell directly from the host tissue.
The role of the choriothete in tsetse flies
Authors: Roberts Michael J.
Published: June 2009

The anatomy of the choriothete and its relation to certain features of the tsetse uterus, such as the previously unnoticed radial, uterine ridges, are described. The results of this study suggest that the choriothete is an organ for support of the developing embryo or larva and this role is taken over by the uterine ridges when the larva reaches a sufficient size. The choriothete then appears to degenerate due to stretching of the uterus until the beginning of the next breeding cycle.

Hatching takes place with the aid of a labral egg-tooth as in some other dipteran larvae and does not require the additional presence of the choriothete.

The uterine ridges also help to form a pool of milk gland secretion around the anterior end of the second-instar larva by locking its body wall to that of the uterus.

I am grateful to Dr E. J. Popham and Col. H. W. Mulligan for reading the text and would like to thank Dr T. A. M. Nash of the Tsetse Research Laboratory, Bristol, for the provision of tsetse material. The work was carried out during tenure of a grant from the Ministry of Overseas Development.
Cyclical transmission of pathogenic Trypanosoma species by gamma-irradiated sterile male Glossina morsitans morsitans
Authors: Moloo S. K.
Published: June 2009

Investigations were conducted on the infection rates and transmission charecteristics of sterile male Glossina morsitans morsitans for Trypanosoma vivax, T. congolense and T. brucei. Pupae were irradiated after the first flush of female emergences with 7, 10 or 13 krad. in a 137caesium radiation source under ambient conditions. The emergent males were fed on a T. viuax-infected goat at peak parasitaemia. They were subsequently mated at 8 days old with 3-day-old normal, virgin females. A batch of sexually fertile males which had been infected as tenerals on the goat at the same time were similarly mated to serve as controls. All the tsetse were maintained on rabbits' ears; the survival and reproductive performance were monitored for seven age-group periods of 9 days each. The sterility rates of the males were 73, 91 and 98% for the 7, 10 and 13 krad. doses of radiation; the percentage of T. vivax infection rates were 78·3, 82·3 and 74·4, respectively. For the control males, the fecundity of the mated females was 90% and the infection rate was 75·7%. In all other experiments, the 10 krad. dose was selected since both the survival and the sterility of the irradiated males were good. The T. vivax-challenged cows and goats died with symptoms of anaemia. There was no difference in the transmission characteristics between sterile and fertile vectors. There was also no significant difference between the sterile and normal males in the infection rates and the transmission frequency of T. congolense and T. brucei to cattle, goats and mice. These results indicate that release of sterile male tsetse in tsetse control programmes will potentially increase the trypanosomiasis risk in the affected area. Consideration must therefore be given to integrating adequate surveillance and chemotherapeutic measures for protection of man and his domestic livestock in the region during the period of such tsetse control campaigns.
Caryophyllidea (Cestoidea): perspectives
Authors: Mackiewicz J. S.
Published: June 2009

Caryophyllids are widely distributed cestodes of the fresh water siluriform and cypriniform fishes of the world. There are about 126 species and 45 genera and they constitute approximately 25% of the cestode fauna of fresh water fish (Mackiewicz, 1972). Benthic-feeding fish become infected by eating tubificid worms (Annelida; Oligochaeta) that harbour the cercomer-beariug, infective stage; the tubificids, in turn, are infected by eating the operculated eggs in mud. Such a brief synopsis belies the fact that these well-known tapeworms are at the very heart of important questions concerning the evolution of Cestoidea. One has but to read Bazitov (1976), Freeman (1973), Kulakovskaya & Demshin (1978), Mameav (1975), Malmberg (1974) and Mackiewicz (1981) to appreciate that great differences still exist as to how caryophyllids evolved and what role they may have played in the evolution of the more numerous strobilate tapeworms.
Some effects of irradiation on the tick Rhipicephalus appendiculatus
Authors: Purnell R. E. , Dargie J. D. , Gilliver B. , Irvin A. D. , Ledger M. A.
Published: June 2009

Groups of Rhipicephalus appendiculatus ticks were given single doses of irradiation (range 0·25–16 krad) at different stages in their life-cycle: unfed nymphs, engorged nymphs, moulting nymphs and unfed adults. The effects of irradiation were assessed by evaluating the subsequent performances of the ticks when fed on rabbits. Observations were carried through until the viability of egg batches from surviving females had been recorded.
Irradiation of unfed and engorged nymphs produced similar effects on the ticks, whilst irradiation of moulting nymphs and adults produced effects which were different from those produced on the other two groups but similar to each other.
Ticks were in general unaffected at irradiation doses below 2 krad, but at this level and above, survival rates, mean engorged weights, percentage egg weights and viability of eggs were reduced, and feeding times were extended.
Male ticks appeared to be more susceptible to the effects of irradiation than female ticks. Males irradiated at 4 krad were sterile, but since they survived doses considerably higher than this they might well prove suitably competitive in further trials should a sterile male release be considered feasable.
The possibility is also considered of irradiating Theileria parva parasites in ticks and thus altering the parasites in some way that could be used in studies of immunisation of cattle against East Coast fever.
Observations on the free-living stages of strongylid nematodes of the horse
Authors: Ogbourne C. P.
Published: June 2009

Observations have been made on the development and survival of the free-living stages in faeces deposited out of doors at different times of year, and on the migration of infective larvae to the surrounding herbage. Laboratory experiments were performed to assist in the interpretation of the field observations. Studies were made on the rate of development to the infective stage in faeces kept at different temperatures. The rates at which eggs and larvae of Strongylus vulgaris, S edentatus, S. equinus and Trichonema nassatum developed on faecal-agar cultures at different temperatures were compared. Studies were also made on the effect of desiccation of faeces on the development and survival of the free-living stages. The results of these observations are discussed in relation to the development of herbage infestations on British pastures.
Host skin mucus as a hatching stimulant inAcanthocotyle lobianchi, a monogenean from the skin ofRajaspp.
Authors: MacDonald Sheila
Published: June 2009

When incubated at 13°C in alternating 12 h periods of light and darkness eggs ofAcanthocotyle lobianchirarely hatch. Hatching was not induced by shadowing or by mechanical disturbance. When skin mucus from the host ray was added to eggs which were more than 15 days old, hatching occurred almost immediately in about 60% of all eggs tested. Susceptibility to host mucus increased with the age of the eggs so that after 26–30 days of incubation over 80% of the eggs tested hatched. Some oncomiracidia were found to remain alive for up to 83 days in the egg, although they appeared to be fully developed at 15 days. Lipid droplets in the body of the 15-day-old oncomiracidia gradually disappeared as the eggs aged and it is suggested that these droplets serve as a food store for resting larvae.
Nippostrongylus brasiliensis: the distribution of primary worm populations within the small intestine of neonatal rats
Authors: Jenkins D. Conwil
Published: June 2009

When neonatal rats were exposed to a small (200 larvae) primary infection of Nippostrongylus brasiliensis the worms that became established in the intestine were found in the mid-jejunum on both the seventh and the fourteenth day after infection. By day 21 most of the worms had migrated to the duodenum where they remained subsequently.

When similar rats were exposed to a heavy primary infection (1500 larvae) the worms were found to be distributed along the length of the duodenum and jejunum by the seventh day. By day 28, however, a proportion of worms equal to that formerly located in the jejunum had been expelled, leaving a population of about 300 worms in the duodenum.

It is suggested that the increased longevity of those worms that survive the effects of host immunity is dependent on their location at the duodenal site. The possibility is raised that the duodenum may be an immunologically privileged site for N. brasiliensis in young rats.
Salivarian trypanosome infections in cattle in Ikoma, South Mara District, Tanzania
Authors: Mwambu P. M. , Mayende J. S. P.
Published: June 2009

798 cattle from the Ikoma area, Musoma district, were examined for evidence of trypanosomiasis and the predominant trypanosome species involved.

From the results, the extent of cattle trypanosomiasis in Ikoma and the predominance of congolense-type infections as compared with vivax-type infections was established.

The need to use more than one method in the diagnosis of animal trypanosomiasis is emphasized from the results presented in Table 3.

The direct relationship between the poor health of the cattle and T. congolense infections demonstrates the economic importance of this trypanosome species as compared with T. vivax. This relationship also supports results of earlier work showing that in East Africa congolense-type infections produce more serious clinical trypanosomiasis in cattle than do vivax-type infections. This is important when drawing up a treatment programme.
The specific immunoglobulin response in cattle immunized with isolated Theileria parva antigens
Authors: Wagner G. G. , Duffus W. P. H. , Burridge M. J.
Published: June 2009

Cattle were inoculated with purified Theileria parva piroplasm and/or schizont antigen. Two similar inoculations were given 10 days apart. Serum samples were regularly collected and the indirect haemagglutination (IHA), indirect immunofluorescence (IFA), complement-fixation (CF) and immunodiffusion (ID) tests were used to detect T. parva antibodies. Selected sera were separated by Sephadex G 200 and fractions examined for specific immunoglobulin activity.

With the IHA test specific antibody first appeared 4 days post inoculation (dpi) and reached high titres by 8 dpi. With the IFA and CF tests specific antibody also appeared 4 dpi and reached high titres by 8–14 and 10–14 dpi respectively. Specific ID activity was detected as early as 6 dpi and persisted for the length of the experiment.

On fractionation of the sera both the IHA and CF tests indicated a sequential production of T. parva IgM and 7S Ig. However, in cattle inoculated with schizont antigen only, a significant 7S Ig component was not detected by the IHA test until 16 dpi, but was demonstrated by the CF test 7 dpi. The IFA test, however, detected anti T. parva activity almost exclusively in the 7S Ig fractions. All cattle were challenged 35–42 dpi with infective T. parva stabilate and all cattle proved fully susceptible. The lack of protection by high titres of specific T. parva immunoglobulin is discussed, together with the data on the differential immunoglobulin response, in relation to previous results.
Aspects of in vivo growth of the plerocercoid stage of Schistocephalus solidus
Authors: Meakins R. H. , Walkey M.
Published: June 2009

1. The in vivo growth of Schistocephalus solidus plerocercoids was investigated by surgical implantation of worms into the body cavity of uninfected, recipient sticklebacks.
2. Burdens of one, two and five worms were used.
3. Results show a reduction in parasite growth with both increasing size and increasing numbers of parasites.
4. Reasons for the decrease in growth rate of multiple burdens are discussed and reference is made to the significance of burden size in completion of the life-cycle under natural conditions.
Studies on the biology of the life-cycle ofTrichuris suisSchrank, 1788
Authors: Beer R. J. S.
Published: June 2009

The biology of the life-cycle ofTrichuris suisof the pig is described and discussed together with aspects of the hosi-parasite relationship. Development of the infective L. 1 larval stage within the egg was shown to be influenced by temperature. Following ingestion of infective ova by the pig, all subsequent larval development to the adult stage occurred in the mucosa of the caecum and colon. Eggs hatched in the distal region of the small intestine and throughout the large intestine. Larvae then penetrated the caecum and colonic mucosa via the crypts of Lieberkühn, where they entered the cells lining the crypts. The ensuing histotrophic phase lasted 13 days, during which time a gradual larval migration occurred from the deeper regions of the lamina propria to areas immediately beneath the surface mucosal epithelium. Luminal development was initially seen on day 16 when the posterior extremities of larvae were protruded into the gut lumen; from day 20 the entire posterior body region was exposed, while only the filamentous anterior region of the parasite remained embedded in the mucosal surface. The prepatent period varied from 41 to 47 days. Four moults were observed during development within the host and these occurred on days 10, 16, 20, 32 and 37 (to form the L. 2, L. 3, L. 4 and L. 5 or adult stage respectively). It is suggested that althoughT. suismay not be an important pathogen in its own right, its activities in the caecal and colonic mucosa may cause sufficient damage to enable secondary pathogenic invaders to become established.
The release of membrane antigens into culture by adult Schistosoma mansoni
Authors: Kusel J. R. , Mackenzie P. E. , McLaren D. J.
Published: June 2009

Antigens sharing determinants with surface membranes and soluble proteins of adult Schistosoma mansoni have been detected in culture media after incubation of radioactively labelled worms. The relative quantities of these antigens were measured with specific antisera raised in rabbits and with serum from an immune rhesus monkey. It was found that 12–16% of TCA-precipitable radioactivity in the culture medium consisted of membrane antigens and 6–8% consisted of antigens sharing determinants with proteins found in the soluble fraction of adult worms. Over half the membrane antigens were present in particulate form, while other antigens were present in solution. Surface labelling the adult worms with [125I]confirmed that some of the particles in the culture medium were derived from the surface membrane of the adult worm and electron microscope examination of such particles showed that large membrane fragments were present. These results support the hypothesis that anti-bodies against schistosome membrane antigens are induced by particulate membrane antigens released by the parasite.
Histochemical demonstration of acetylcholinesterase in sporocysts of Schistosoma mansoni (Trematoda)
Authors: Diconza Joseph J. , Basch Paul F.
Published: June 2009

The distribution of acetylcholinesterase in mother and daughter sporocysts of Schistosoma mansoni was studied histochemically. In young mother sporocysts derived from miracidia cultured in vitro the miracidial neural mass and flame cells were shown to persist. The nerve trunks and commissures, as well as papillae, are apparently lost in the transformation process. In young daughter sporocysts freshly dissected from mother sporocysts there was little enzyme activity except for a sparse distribution in the tegument. After cultivation, intense enzyme activity was associated with developing cercarial embryos. A similar distribution of activity was observed in older daughter sporocysts obtained from the digestive gland of snails. No evidence of flame cells, neural mass, or commissures was detected in daughter sporocysts by the methods employed.
Utilization of amino acids byTrypanosoma bruceiin culture: L-threonine as a precursor for acetate
Authors: Cross G. A. M. , Klein R. A. , Linstead D. J.
Published: June 2009

The amino acid compositions of several culture media have been analysed and compared. The utilization and excretion of amino acids and other metabolites have been followed during growth ofTrypanosoma bruceiS42 in a defined medium. All of the added L-threonine was metabolized by the cells, even when it was present at elevated concentrations. Glucose was consumed throughout the growth cycle: glutamine was consumed more rapidly than glutamic acid, which was itself used at about the same rate as proline. Threonine was cleaved to form glycine and acetate, both of which accumulated in the medium. Alanine and succinate were excreted together with a small amount of pyruvate, but these three products accounted for less than half of the glucose used. CO2production from glucose was not measured, but insignificant amounts of CO2were produced from threonine. Tetraethylthiuram disulphide blocked the cleavage of threonine and was a potent inhibitor of trypanosome growth.
Schistosoma mansoni: in vitro conversion of cercariae to schistosomula
Authors: Eveland L. K. , Morse S. I.
Published: June 2009

Schistosoma mansoni cercariae were incubated for 3–5 h at 37°C in various test solutions, and the rate and extent of conversion of th ecercariae to schistosomula were determined. Criteria used to identify schistosomula included: (1) loss of cercariai tail, (2) viability of organisms in saline but not in water, (3) pre-acetabular gland evacuation and (4) ability to survive in culture.
Echinococcus granulosus: developmentin vitrofrom oncosphere to immature hydatid cyst
Authors: Heath D. D. , Lawrence S. B.
Published: June 2009

Echinococcus granulosuscysts were culturedin vitrofrom the oncosphere, and cyst morphogenesis is described. Cysts grew to a mean diameter of 16 mm in 120 days, with a maximum of 20 mm. An amorphous layer was apparent around the larvae during early post-oncospheral re-organization. Organisms became vesicular at 6 days and laminations appeared in the amorphous layer at 10 days. Confluence of proliferating cells to form the syncytium of the germinal membrane was observed.
Fasciola hepatica: the ultrastructure of the epithelium of the seminal vesicle, the ejaculatory duct and the cirrus
Authors: Threadgold L. T.
Published: June 2009

The ultrastructure of the seminal vesicle, ejaculatory duct, cirrus sac and cirrus is described. The epithelium of the seminal vesicle consists of a single layer of squamous to cuboidal cells. The apical ends of the cells have thin polymorphic lamellae and long narrow pits, both of which enclose normal spermatozoa. The cells have a moderate amount of GER and Golgi complexes which produce a lucid secretory body. The ejaculatory duct epithelium is composed of cuboidal to columnar cells between or through which project the terminal parts of the ducts of the unicellular prostate glands. The apical surfaces of the epithelia are extended into triangular or filiform projections having thin sinuous lamellae. The cytoplasm contains GER cisternae and Golgi complexes which synthesize a dense ovoid secretion. The cirrus sac and cirrus are covered by a thin modified tegument. The cirrus has many spines and the normal ratio of T1 to T2 type of secretory bodies, whereas the cirrus sac has few spines and the T2 type of secretory body predominates over the T1 type. The significance and possible functions of the structures observed in the three tissues are discussed.
Structure and invasive behaviour ofPlasmodium knowlesimerozoitesin vitro
Authors: Bannister L. H. , Butcher G. A. , Dennis E. D. , Mitchell G. H.
Published: June 2009

The structure and invasive behaviour of extracellular erythrocytic merozoites prepared by a cell sieving method have been studied with the electron microscope.

Free merozoites contain organelles similar to those described in late schizonts ofPlasmodium knowlesi. Their surface is lined by a coat of short filaments. On mixing with fresh red cells, merozoites at first adhere, then cause the red cell surface to invaginate rapidly, often with the formation of narrow membranous channels in the red cell interior. As the merozoite enters the invagination it forms an attachment by its cell coat to the rim of the pit, and finally leaves this coat behind as it is enclosed in a red cell vacuole. Dense, rounded intracellular bodies then move to the merozoite periphery, and apparently rupture to cause further localized invagination of the red cell vacuole. The merozoite finally loses its rhoptries, the pellicle is reduced to a single membrane and the parasite becomes a trophozoite. Invasion is complete by 1 min after adhesion, and the trophozoite is formed by 10 min.
Some influences of population density on Hymenolepis diminuta in rats
Authors: Hesselberg Carl Aage , Andreassen Jørn
Published: June 2009

When measured 56 days postinfection the length, wet weight and dry-weight of Hymenolepis diminuta were all found to decrease with increasing number of cysticercoids given up to 20. The mean position of the worms in 10, 12 and 20 worm infections is significantly posterior to that of 1, 2 and 5 worm infections and the worms are attached over a wider area of the intestine.

Egg production by the worms was followed up to day 56 postinfection; the number of eggs produced per worm and even per rat decreased with increasing population density. Thus the best way to get most eggs and to maintain the parasite in the laboratory is to have rats infected with only one tapeworm.

Rats given 1–20 cysticercoids showed a mean recovery of 100–65%, while rats given 40–200 cysticercoids showed a mean recovery ranging from 13 to 2%. In addition to ‘normal’ worms, defined as worms > 10 mm, small, most probably destrobilated, worms were found. In the 50 and 100 cysticercoid infections, worm recoveries were, respectively, 8% ‘normal’, 16% small, and 2% ‘normal’, 5% small. From the significantly lower recovery from heavy infections it is concluded that a deleterious factor is operating during the 8 weeks after the infection.
Protection of mice againstBabesiaspp. andplasmodiumspp. with killedCorynebacterium parvum
Authors: Cleark I. A. , Cox F. E. G , Allison A. C.
Published: June 2009

Mice which had been pre-treated with killedCorynebacterium parvumgiven intravenously or intraperitoneally, but not subcutaneously, were completely resistant ot infection withBabesia microtiorB. rodhaini, and protected from death caused byPlasmodium vinckeiorP. chabaudiinfection. There is evidence that the parasites died within circulating erythrocytes. This occurred much too soon for a specific antibody response to be evoked, and no antibody could be detected by the indirect fluorescent-anitbody technique. Thus it is suggested that a non-secific soluble mediator may play an important role in the protection observed.
Flight muscle ultrastructure of susceptible and refractory mosquitoes parasitized by larvalBrugia pahangi
Authors: Lehane M. J. , Laurence B. R.
Published: June 2009

On parasitization with larvalBrugia pahangithe infected flight muscle fibres of ‘resistant’Anopheles labranchiae atroparvusundergo the following ultrastructural changes. The fibres become almost totally devoid of glycogen, their sarcoplasmic reticulum becomes elongate and closely associated with muscle fibrils. These fibrils degenerate and vesicles appear both within the degenerate fibril and within elements of the sarcoplasmic reticulum. Vesicles accumulate around the worm and degenerate to a uniform mass which eventually becomes melanized from its inner edge (next to the parasite) outwards.

The infected flight muscle fibres of both ‘resistant’Aedes aegyptiand ‘susceptible’Aedes togoiare almost totally devoid of glycogen granules, but show no other ultrastructural change from the uninfected state.
Changes in the adenylate energy charge ofNippostrorigylus brasiliensisandNematodirus battusduring the development of immunity to these nematodes in their hosts
Authors: Ballantyne A. J. , Sharpe M. J. , Lee D. L.
Published: June 2009

Infection of rats with 2000 infective juveniles ofNippostrongylus brasiliensisand of lambs with 60000 infective juveniles ofNematodirus battusresults in a well-marked immunity to these nematodes in their respective hosts. There is a fall in the adenylate energy charge value of these nematodes during the course of these infections, reaching values of 0·37 in males and 0·27 in females ofN. brasiliensis, and 0·31 in males and 0·23 in females ofN. battustowards the end of the infections. In hosts given relatively small numbers of infective juveniles, the values for the nematodes removed from the hosts late in the infection remain at a relatively high level. These results indicate that the immune response of the host may affect the energy status of these nematodes, and this could help to explain their subsequent expulsion from the immune host.
Strongyloides ratti in virgin female rats: studies of oestrous cycle effects and general variability
Authors: Wilson P. A. G. , Cameron Maureen , Scott D. S.
Published: June 2009

There were no differences in mean intestinal worm burdens 8 days after subcutaneous injection of 4000 infective larvae of Strongyloides ratti into rats in dioestrus, pro-oestrus, oestrus and metoestrus. Thus, changes in the hormonal environment of the migrating larvae dependent on the oestrous cycle did not alter the worms' destination or affect their potential for development. In particular, the results are prima facie evidence that prolactin is not, on its own, responsible for the re-orientation of larvae in the tissues of nursing mothers. Other sources of variability in experimental S. ratti infections are analysed and the ‘exact dose’ technique offered as a corrective for some procedural errors.
Evidence for the involvement of a bone marrow-derived cell population in the immune expulsion ofTrichinella spiralis
Authors: Wakelin D. , Wilson Margaret M.
Published: June 2009

When mice were irradiated immediately before infection withTrichinella spiralisthere was a profound and long-lasting interference with their ability to expel adult worms from the intestine. Irradiation given after the fifth day of infection was progressively less effective in this respect. The ability to expel worms was not restored when mesenteric lymph node cells (MLNC) were transferred (a) on the day of infection in mice irradiated one day previously, or (b) on day 7 of an infection in mice irradiated on day 6, even though the MLNC transferred immunity to intact recipients. Transfer of bone marrow (BM) alone was also without effect. However, worm explusion was restored if, following irradiation and injection of BM, 10 days were allowed for BM differentiation before transfer of MLNC. This restoration was effective even after lethal levels of irradiation and was clearly dependent upon a donor-derived BM component cooperating with, or responding to, the activity of the transferred MLNC. The possibility that the BM component is non-lymphoid in nature is discussed.
The life-cycle of Rasajeyna nannyla n.gen., n.sp., a coccidian pathogen of Tipula paludosa Meigen
Authors: Beesley J. E.
Published: June 2009

A coccidium belonging to the family Adeleidae was discovered in the mid-gut cells of Tipula paludosa. A new genus Rasajeyna and a new species nannyla are established because this pathogen differs from previously described coccidia. A diagnosis of R. nannyla is given.

The endogenous phase of R. nannyla is restricted to larvae. The oocysts, which are the external phase of the parasite, are swallowed by the leatherjackets and excyst in the anterior mid-gut. The sporozoites, 36·5 µm (± 5·4 µm, 95% confidence limits) long, 15·7 µm (± 1·8 µm, 95% confidence limits) wide, each containing a refractile body, enter the anterior mid-gut cells where the 1st schizogony occurs. The refractile bodies are retained during the early nuclear divisions. The sausage-shaped merozoites, 28·2 µm (± 4·3 µm, 95% confidence limits) long, 7·1 µm (± 0·9 µm, 95% confidence limits) wide, with posterior nuclei exhibit three distinct types of movement. (a) An active flexion of the body which is thought to occur during the intracellular phase. (b) A flicking action by both ends of the body. This is thought to occur during the free phase. (c) A spiralling motion which is thought to aid the entry of the merozoite into the cells.

The nucles of the intracellular merozoite divides several times, forming a multinucleate body. The merozoites of the 2nd schizogony form in groups at the poles of the schizont. The merozites are indistinguishable from each other until after a period of growth has ensued, when they are differentiated as macro- and microgametocytes. The pear-shaped macrogamete 44·3 µm (± 4·5 µm, 95% confidence limits) long, 21·6 µm (± 3·2 µm, 95% confidence limits) wide, which contains a crescent-shaped structure in the nucleus. The microgametocyte grows to 40·3 µm (± 2·7 µm, 95% confidence limits) long, 16·7 µm (± 1·5 µm, 95% confidence limits) wide and then attaches itself lengthwise to the macrogamete. A membrane is then secreted around both partners. Nuclear division produces 4 microgametes, one of which fertilizes the female. The 1st and 2nd oocyst membranes are deposited before cytoplasmic shrinkage and meiosis. The zygote is 44·6 µm (± 4·2 µm, 95% confidence limits) long and 33·7 µm (± 4·1 µm, 95% confidence limits ) wide. Cytoplasmic condensation around the nuclei forms the sporoblasts which mature into sporocysts each containing 1 sporozoite. The zygote may be expelled from the larvae at any juncture after fertilization.
Oxygen uptake byDiclidophora merlangi(Monogenea)
Authors: Arme C. , Fox M. G.
Published: June 2009

Diclidophora merlangiwas found to consume oxygen under a variety of experimental conditions. TheQo2of homogenates was 0.415 μl oxygen consumed/mg wet wt/h. Oxygen uptake was reduced in the presence of inhibitors: cyanide 0.1 mM and 5.0 mM, 100%; rotenone 10−6M, 56%; antimycin A10−6M, 63 %; malonate 10 mM, 36 %; arsenite 5 mM, 46 %; fluoroacetate 5 mM, 47 %. Worms died after 1 h incubation in 1 mM cyanide. It is suggested that these data provide evidence for the existence of a functional TCA cycle and respiratory chain of the classical pattern in this fluke.
Studies on enzyme variation in the murine malaria parasitesPlasmodium berghei,P. yoelii,P. vinckeiandP. chabaudiby starch gel electrophoresis
Authors: Carter Richard
Published: June 2009

Electrophoretic variation of the enzymes glucose phosphate isomerase, 6-phosphogluconate dehydrogenase, lactate dehydrogenase and glutamate dehydrogenase (NADP-dependent) has been studied in the African murine malaria parasitesPlasmodium berghei,P. yoelii,P. vinckeiandP. chabaudiand their subspecies. Horizontal starch gel electrophoresis was used throughout. The number of isolates examined in each subspecies varied from 1 (P. y. nigeriensis) to 24 (P. c. chabaudi). Extensive enzyme variation was found among isolates of most of the subspecies from which more than two such isolates were available for study. It is clear that the phenomenon of enzyme polymorphism is of common occurrence among malaria parasites. With the exception ofP. bergheiandP. yoelii, of which all isolates share an identical electrophoretic form of lactate dehydrogenase, no enzyme forms are shared between any of the 4 species of murine plasmodia. By contrast, within each species common enzyme forms are shared among each of the subspecies. The subspecies are, nevertheless, distinguished from each other by the electrophoretic forms of at least one enzyme.

The distribution and reassortment of enzyme variation among isolates of a single subspecies is in accordance with the concept of malaria parasites as sexually reproducing organisms. The study of variation among parasites present in individual wild-caught rodent hosts demonstrates that natural malarial infections usually comprise genetically heterogeneous populations of parasites. Nevertheless, the number of genetically distinct types of parasite of any one species present in a single infected host appears to be small. Generally not more than 2 or 3 clones of parasite of distinct genetic constitution are present in a single infected animal.
The metabolic profile of adultFasciola hepaticaobtained from rafoxanide-treated sheep
Authors: Prichard R. K.
Published: June 2009

Sheep infected with adultFasciola hepaticawere drenched with rafoxanide. At 4, 8, 16 and 24 h after drenching the sheep were killed and the flukes removed, washed and rapidly frozen in liquid nitrogen. The content of key metabolites in the fermentation pathway were determined and compared with those in controlF. hepatica, whose hosts were not treated with rafoxanide.

Rafoxanide decreased glycogen, malate, NADH and ATP levels. The level of other metabolites in the pathway increased for the first 8–16 h after rafoxanide treatment. The marked decrease in ATP and glycogen, and the increase in total [NAD+]/[NADH] and [oxaloacetate]/[malate], together with the changed content of other metabolites, led to the conclusion that the mode of action of rafoxanide againstF. hepatica in vivois by uncoupling oxidative phosphorylation.
Antibody dependent cell-mediated cytotoxicity of Trypanosoma cruzi: the release of tritium-labelled RNA, DNA and protein
Authors: Sanderson C. J. , Moreno Marlene M. Bunn , Lopez Angel F.
Published: June 2009

The cytotoxicity of normal rat spleen cells to antibody-coated Trypanosoma cruzi epimastigotes has been studied by assaying the release of [3H]-labelled macromolecules from the parasites. The release of thymidine (DNA) is slower than the release of uridine (RNA), suggesting that the nucleus is broken down more slowly than the cytoplasmic membrane. Less than 50% of the leucine (protein) is released when the parasites are lysed, whereas uridine (RNA) is almost totally released. In practical terms these results show that the release of incorporated radioisotope-labelled uridine can be used as a sensitive assay for cytotoxicity of T. cruzi. Cytotoxicity by normal rat spleen cells is antibody dependent and proportional to the logarithm of effector cell number. The lag phase and the rate of RNA release is not altered by centrifuging the parasites and effector cells to enhance contacts between them.
Experimental investigations on the behaviour of the cercariae of an ectoparasitic digenean transversotrema patialense: general activity patterns
Authors: Whitfield P. J. , Anderson R. M. , Bundy D. A. P.
Published: June 2009

The activity patterns of the cercariae of Transversotrema patialense have been examined by monitoring the behaviour of individual larvae. Records of three different behavioural modes, namely active, tail–first swimming, passive dropping and resting periods were made separately. The age- and temperature–dependence of the activity patterns during the spontaneously active life of the cercariae were examined and estimates made of the absolute speeds of swimming and dropping. Through the temperature range 25–32° C, the spontaneously active life of cercariae declined from about 18 h to about 6 h. Within this interval, after an initial period of high activity rates, a gradual decline in activity followed. The decline was a result of a decreasing frequency of swimming events rather than any change in the durations of such events. The neural control and energetic significance of the cercarial activity patterns are discussed.
Impairment of primary expulsion of Trichuris muris in mice concurrently infected with Nematospiroides dubius
Authors: Jenkins Simon N , Behnke Jerzy M
Published: June 2009

Primary immune expulsion of Trichuris muris was markedly delayed by concurrent infection with Nematospiroides dubius. Maximum delay of expulsion was dependent on size and timing of N. dubius infection relative to T. muris infection. In NIH mice infection with 400 N. dubius larvae immediately before or after T. muris infection was found to be most effective in suppressing expulsion. Infection on day 8 of T. muris infection, when mice are sensitized to T. muris, also impaired expulsion. From this evidence it is suggested that the larvae of N. dubius are immunosuppressive and that the efferent role of the immune response to T. muris is inhibited. The results are discussed in terms of non-specific immunosuppression and their relevance to the tropical disease situation is emphasized.
Schistosoma mansoni: differential cell death associated with in vitro culture and treatment with Astiban (Roche)
Authors: Shaw J. R. , Erasmus D. A.
Published: June 2009

A simple technique for the maintenance in vitro of mature Schistosoma mansoni is described and critically assessed at the ultrastructural level. Females were cultured for 4–6 days with no apparent ultrastructural change, but after this period changes appeared in the cells of the ovary and vitelline gland. At a later stage (10–12 days) lipid bodies appeared in the parenchyma cells. These changes occurred in worms which were active, paired with males and were egg–laying. Thus the activity, pairing behaviour and egg–laying characteristics are not adequate to reveal the true morphological condition and presumably the physiological and biochemical status of cultured worms.

This technique was used to study the effect of Astiban on females and the results were compared with worms treated in vivo. Astiban concentrations greater than 30 µg/ml killed worms within 7–20 h and acted non–selectively. Astiban at low concentrations (10µg/ml) during short–term culture (1–3 h) resulted in a selective action of the drug on maturing vitelline cells. Thus, although the degree of cell damage caused by drug treatment was more severe and occurred earlier than the effects observed in worms cultured in vitro without drugs, both treatments resulted in differential cell death.
Efficacy and cross-resistance studies on N, N′-bis (3,4 ditrifluoromethylphenyl) methylmalonamide, a novel anticoccidial agent
Authors: Panitz E.
Published: June 2009

N, N′-bis (3,4 ditrifluoromethylphenyl) methylmalonamide (Sch18545) completely controlled a mild Eimeria necatrix infection at 50, 40 or 30 p.p.m. in the diet, and controlled E. tenella infections at 50 and 40 p.p.m. Slight oocyst passage was observed at each E. tenella treatment level with a marked increase at the 30 p.p.m. treatment level. Fifty p.p.m. were necessary to control E. acervulina infections; levels of 40 p.p.m. reduced E. acervulina oocyst production while 30 p.p.m. were ineffective. Evaluations of Sch 18545 using a mixed infection (Coccivac D®) further suggested that activity with this compound was weakest against E. acervulina. Weight gains decreased with increasing concentration of drug in the diet of treated, infected birds and thus the compound showed an insufficient safety margin to be of practical value. Sch 18545 administered at 35 p.p.m. in the diet was effective against amprolium, zoalene, aklomide or nicarbazin-resistant strains of E. tenella.
Studies on Eimeria dispersa Tyzzer 1929 in turkeys
Authors: Long P. L. , Millard B. J.
Published: June 2009

Eimeria dispersa was isolated from young, intensively housed turkeys in Britain. The parasite has morphological features in common with those of the original description. At least two generations of schizonts occur before gametogony and one or two more schizont generations are concurrent with gametogony. Four generations of schizonts are needed to account for the observed reproduction index of 2·08 × 106/oocyst inoculated. The first oocysts were discharged by 105 h and these sporulated. within 30 h at 30 °C. A single dose of between 1 × 102 and 1 × 106 oocysts depressed body weight gain of 3-week-old poults and 2 poults died 6 and 12 days after receiving 1 × 104 or 1 × 106 oocysts. A single dose of oocysts protected against a challenge inoculation given 14 days later. Poultsimmunized against E. dispersa were resistant to challenge with a strain of E. dispera obtained from the United States. Electrophoretic examination of 2 enzymes from both strains of E. dispersa showed that they had similar mobilities. Attempts to infect chickens, guinea-fowl and Japanese quail with E. dispersa were unsuccessful. The strain of E. dispersa isolated here is best referred to as E. dispersa (Briston).
The possible role of the frontal and sub-parietal gland systems of the pentastomidReighardia sternae(Diesing, 1864) in the evasion of the host immune response
Authors: Riley J. , James J. L. , Banaja A. A.
Published: June 2009

The frontal and sub-parietal glands of the pentastomidReighardia sternaeelaborate lamellate secretion which is poured on to the cuticle. The entire surface of the cuticle, including the mouth, hook pits and reproductive apertures, is coated with secretion. Electron microscope studies indicate that the glands are continuously active, which implies a turnover of surface membranes. The postulated function of these membranes is to protect certain vital areas of the host–parasite interface, notably the pores of ion-transporting cells, from the host immune response. The available evidence suggests that pentastomids do evoke a strong immune response but since most are long-lived they must circumvent it. We believe the surface membrane system to be instrumental in this. Studies on another pentastomid,Porocephalus crotaliin rats have shown that an immune response stimulated by a primary infection will kill subsequent infections and that the surface membranes are strongly immunogenic. Obvious parallels between this situation and that of schistosome infections in mammals are discussed. An alternative explanation of concomitant immunity is proposed.
Effects on cattle of artificial infestations with the tick Rhipicephalus appendiculatus
Authors: Castro J. J. De , Cunningham M. P. , Dolan T. T. , Dransfield R. D. , Newson R. M. , Young A. S.
Published: June 2009

Groups of ten cattle were exposed to 0, 40 and 400 adult Rhipicephalus appendiculatus feeding once a week for 24 weeks. Although no differences in cumulative percentage weight gain were found at the end of the experiment, animals free of ticks performed better during the first 12 weeks. A marked recovery of the 400-tick group was recorded during weeks 13–24 and after ticks were removed. Haemoglobin and packed cell volume values were lowered in tick-infested animals but no clear trends were observed in red and white blood cells. No differences between the percentages of ticks feeding in the 2 tick-infested groups on day 2 were observed but higher numbers of females were feeding on the 40-tick group on day 5. More ticks were found on day 5 after tick application to the cattle during weeks 1–6 than in the rest of the experiment. Significant correlations were found between lymph node enlargement and ear damage when they were tested against tick load. R. appendiculatus nymphs feeding on the formerly tick-infested cattle were fewer, lighter and engorged in a shorter time than those on the control animals. The possible causes for the reduction in ticks feeding, the changes in cattle weights, blood composition and development of host resistance are discussed.
Transplantation of adult Trichinella spiralis between hosts: worm survival and immunological characteristics of the host–parasite relationship
Authors: Kennedy M. W. , Wakelin D. , Wilson Margaret M.
Published: June 2009

A technique for the transplantation of Trichinella spiralis worms directly into the host intestine is described. Infections established by the direct transfer of adult worms were essentially normal both in terms of their survival and reproduction and in their stimulation of, and susceptibility to, host immune responses. Worms transplanted from NIH mouse donors at intervals after infection had an equal ability to survive in the recipient, even when taken from the donor shortly before or during the process of worm expulsion, showing that expulsion does not require worms to be irreversibly damaged. It was noted, however, that after 7 days in the donor the ability of the worm to reproduce in the recipient was temporarily impaired.