bluuebunny/crossref_metadata_2025 huggingface dataset:
A note on the effects of antimalarial drugs on the sporogonous cycle of Plasmodium cynomolgi in Anopheles stephensi
Authors: Terzian Levon A.
Published: June 2009

It has been shown that in common with other malarial species the drug response in the sporogonous cycle of Plasmodium cynomolgi parallels in a special way the drug response in the schizogonous cycle. Thus, prophylactic drugs produce deteriorating changes in the oocysts while curative drugs have a destructive effect on the sporozoites. A comparison of the effects of prophylactic drugs on the sporogonous and schizogonous cycles of the four malarial species studied thus far suggests the presence of more than one pre-erythrocytic developmental stage in the schizogonous cycles of P. vivax and P. cynomolgi following the initial invasion by the sporozoite.
The inhibitory effect of CO2 on the ecdysis of infective Haemonchus contortus cayugensis larvae
Authors: Slocombe J. Owen D. , Whitlock J. H.
Published: June 2009

Infective Haemonchus contortus cayugensis larvae were stimulated to exsheath in 0·02 m-Na2B4O7. 10H2O, into which was bubbled CO2. The larvae under the exsheathing stimulus were found to be coiled and sluggish. The larvae became very active after most of the CO2 was removed by compressed air, oxygen or nitrogen. The exsheathment rate in each of the latter instances was higher than when larvae were exsheathed completely in an atmosphere of CO2. Carbon dioxide is an essential component of the exsheathing stimulus, but the continued presence of a high pCO2 or carbonic reaction products appeared to inhibit larval motility and caused lower exsheathment rates.
Experiments on the reproduction ofNippostrongylus brasiliensisin the rat intestine
Authors: Phillipson R. F.
Published: June 2009

A method is described for producing unisexual infections ofN. brasiliensisin rats; this method was used primarily to obtain populations of virgin adult females. Experiments were carried out in which male worms were introduced to virgin females in the rat small intestine. The worms were recovered after periods varying from 30 min to 22 h and the females were examined for fertile egg production or other evidence of insemination.

In some experiments a few females were inseminated within 30 min of being mixed with males, but for reliable results a period of over 1 h was necessary. Sperm were first deposited along the ventral wall of the vagina and there was evidence that a single insemination could fill the vagina. After 4·5 h the majority of females had been inseminated and this period was long enough for sperm to reach the seminal receptacle in one female. A minority of females had a few fertile eggs in the uterus by 5·5 h, and fertile eggs were being passed by 6·0 h after the introduction of males.

Small numbers of males were introduced to an excess of virgin females in order to obtain information on the sexual capacity of males. These experiments indicated that males could, on average, fertilize one female every 2 h during the first 15–20 h. This potential was shown to be greatly in excess of the minimum requirements for maintaining the maximum fertile egg output of females in normal infections.
Temperature as a critical factor in the mating behaviour of the rat flea,Nosopsyllus fasciatus(Bosc.)
Authors: Iqbal Q. J. , Humphries David A.
Published: June 2009

1. Both male and femaleN. fasciatusnormally require a blood meal before they will mate.

2. Fed males do not attempt to mate with unfed females. It is suggested that the taking of a blood meal enables the female to provide a stimulus necessary for the male to show mating behaviour.

3. UnfedNosopsyllusof both sexes will mate if subjected to a temperature between 30 and 35°C inclusive. Above 35° mating does not occur.

4. Below 30°C mating occurs only if the fleas have previously been subjected to a temperature of 30°C or above. A temperature rise to the critical point thus acts as a trigger for an enabling process which continues after temperature has again fallen.

5. It is suggested that the effect of a blood meal in enabling mating to occur may be explained by the fleas' experience, while on the host, of a rise in temperature to the level critical for mating.
Nematode parasites of Oceanica
Authors: Wakelin D. , Schmidt Gerald D. , Kuntz R. E.
Published: June 2009

The capillariid nematodes present in passeriform hosts collected in Taiwan are recorded and described. Two new species are established, Capillaria parusi sp.n. from Parus monticolus insperatus and Sitta europaea formosana, and C. madseni sp.n. from Corvus macrorhynchus colonorum, and their affinities are discussed. Capillaria tridens, C. longifila and C. contorta are recorded from a number of new hosts.
Some effects of irradiation on Theileria parva in the salivary glands of the tick Rhipicephalus appendiculatus
Authors: Purnell R. E. , Ledger M. A. , Obatre J. B.
Published: June 2009

Groups of R. appendiculatus ticks infected with T. parva were irradiated at doses varying from 0 to 32 krad and then applied to rabbits; 3 and 4 days later their salivary glands were removed, processed and examined. Increasing doses of irradiation resulted both in a decreased infection rate of ticks and a decrease in the number of parasite masses observed in infected ticks. No normal parasite masses were seen after doses of 4 krad or above.
On the relationship between abomasal electrolytes and some population parameters of the nematodes Haemonchus contortus and Nematodirus battus
Authors: Mapes C. J. , Coop R. L.
Published: June 2009

Possible relationships between the numbers and development and growth of Haemonchus contortus and Nematodirus battus during concurrent infections and the levels of abomasal pH and Na+ were investigated in 2- to 3-month-old and 8-month-old lambs. The percentage of Haemonchus in the fourth larval stage was found to be positively related to the levels of abomasal electrolytes, while the mean lengths of the worms in the total male and female populations and in the fifth-stage populations were negatively related to these parameters. The numbers of Nematodirus and the mean lengths of worms in the total and fifth-stage populations were negatively related and the percentage of worms in the fourth-stage positively related to abomasal pH and Na+ levels. It is suggested that the changes in abomasal physiology caused by massive infections of Haemonchus directly affect the growth and development of this abomasal parasite. It is also suggested that the changes in the abomasal contents entering the proximal part of the small intestine during such infections of Haemonchus alter the intestinal environment and that this alteration directly affects the course of development of concurrent infections of Nematodirus.
Amino acid flux in the sporocysts ofCercaria emasculansPelseneer, 1906in vitro
Authors: Watts Stuart D. M.
Published: June 2009

Quantitative paper chromatography and radioactive tracers were used to study the flux of alanine through the sporocysts ofCercaria emasculans in vitro. The following evidence indicates that simple diffusion is the main mechanism of permeation: (1) the sporocysts cannot accumulate alanine against a concentration gradient; (2) the concentration of alanine in the sporocysts is a direct linear function of the concentration of alanine in the external environment; (3) addition of 10−2M glucose to the medium does not enhance permeation; (4) neither heat-killing the sporocysts nor treating them with 10−3M iodoacetate slows the rate of permeation; (5) theQ10's for the permeation are similar to those to be expected in a process involving simple diffusion; (6) the amino acid molarities in the parasite and host tissuesin vivoare strikingly similar. No utilization of alanine during the course of 3 h incubations could be detected by autoradiography.

The dynamic nature of the equilibrium between the sporocysts and the external environment is emphasized by the exchange of alanine that occurred even under isotonic conditions.

Fresh sporocysts leaked alanine and proline during 1 and 4 h incubationsin vitro. The significance of this is not known.
Haemonchus contortus - haematological changes in lambs during prolonged exposure to daily and weekly doses of infective larvae
Authors: Pradhan S. L. , Johnstone I. L.
Published: June 2009

Thirty-five lambs (14 weeks old), the progeny of Border Leicester rams mated with Border Leicester × Merino ewes were divided at random into two groups. Seventeen lambs received 3500 Haemonchus contortus larvae at weekly intervals (weekly group) and 18 lambs received 500 larvae each day (daily group). The dosage was decreased to 1400 and 200 larvae respectively after 8 weeks.

The daily infection with a small number of larvae induced a severe anaemic condition with the blood picture falling to 7% PCV; 2% Hb conc. and 1·6m/mm3 RBC count in 78 days. The anaemia with weekly dosing of larvae was less severe with equivalent figures of 10–12% PCV; 4% Hb conc and 3·6m/mm3 RBC count.

Two phases were observed in the changes in the sodium (Na+e) and potassium (K+e) electrolyte concentrations. In the first phase (K+e) increased and (Na+e) decreased, while in the second phase both electrolytes increased. The influx of young red blood cells into the circulation is considered as the factor responsible for these changes.
Nutritional requirements for protein synthesis during parasitic development of the entomophilic nematode Mermis nigrescens
Authors: Gordon Roger , Webster John M.
Published: June 2009

Adult desert locusts were experimentally infected with a dose of 50 M. nigrescens ova and larval nematodes removed 14, 17, 21 and 24 days afterwards for in vitro radiotracer studies. These nematodes were incubated under controlled conditions either in a nutrient medium or in insect saline, which contained the appropriate 14C or 3H-labelled radioisotope. The rate of incorporation of the radioisotope into the proteins of the nematode was measured.

The rate of incorporation of 14C-leucine into proteins was greatest for the 17- day-old larvae and this accorded with the in vivo growth pattern of the nematode. This isotope was incorporated less rapidly into proteins by the 14-, 21 and 24-day- old larvae, which synthesized proteins at approximately the same rates as each other. A non-linear rate of incorporation was manifest for each of the larval stages.

Total dry weight and protein determinations showed that the nematode synthesizes relatively large quantities of non-proteinaceous reserves during the third week of infection, whilst proteins are preferentially synthesized between the 21st and 24th days of infection.

The 17-day-old nematode larvae were able to incorporate six 14C-amino acids into proteins to varying degrees. Leucine was incorporated most effectively into nematode proteins, whilst glutamic acid was the least incorporated of the six amino acids.

These nematode larvae could not effectively metabolize the 3H-dipeptide histidyl-leucine and incorporate its component amino acid residues into proteins. Similarly, a preparation of 3H-haemolymph proteins were not significantly metabolised and incorporated into proteins by the nematode. However, the nematode metabolized and incorporated an exogenous source of 14C-glucose into proteins at relatively high levels.

Incorporation of 14C-luecine into proteins was seven times more rapid for nematodes incubated in buffered insect saline than for those incubated in a more complete nutrient medium.

The dietary requirements of the nematode for protein synthesis were discussed in relation to their associated effects upon the host metabolism and an active transport of dietary amino acids into the nematode was postulated.

We wish to thank Dr H. L. Speer and Dr K. K. Nair for their helpful suggestions regarding radioisotope techniques. Thanks are also due to the National Research Council of Canada for providing financial assistance (Grant No. A4679).
Gastro-duodenal motor and transit disturbances associated with Haemonchus contortus infection in sheep
Authors: Bueno L. , Dakkak A. , Fioramonti J.
Published: June 2009

Abomasal and duodenal motility was investigated by electromyography in 4 lambs fitted with permanent abomasal and duodenal cannulae and infected twice with 25000 Haemonchus contortus larvae at an interval of 39 days. In addition, abomasal and duodenal pH, flow rate of digesta of the duodenum, and faecal water content were determined. The 80–90 min cycles of antral contractions were shortened for at least 3 weeks after infection. This was accompanied by a 26% increase in the number of duodenal migrating myoelectric complexes/day during the intra-parietal development of the larvae (10–12 days). Concomitantly, the duodenal flow of digesta increased from 215 ± 22 ml/h to 318 ± 15 ml/h 4 days after infection and was associated with a higher water content of the faeces. The frequency of the migrating myoelectric complexes, but not the duration of antral motor cycles (or the duodenal flow rate), was correlated with both gastric (P < 0·01) and duodenal (P < 0·05) pH after the first and second infections. The duodenal flow rate was correlated with the Cl− concentration of the abomasal contents (P < 0·01) and with the duodenal pH (P < 0·05). It is concluded that, (i) the duodenal motor disturbances associated with experimental H. contortus infection are related to the alterations in abomasal gastric acid secretion which occurs during the histotrophic phase of larval development and (ii) the increased duodenal flow is a consequence of ionic permeability changes of the gastro-intestinal mucosae.
Antagonism of Echinostoma liei (Trematoda: Echinostomatidae) against the trematodes Paryphostomum segregatum and Schistosoma mansoni
Authors: Heyneman D. , Lim H.-K. , Jeyarasasingam U.
Published: June 2009

Echinostoma liei, a newly described 37-spined eehinostome from Egypt, was tested against two trematodes in paired infections in the snail host, Biomphalaria glabrata (NIH strain). E. liei, when matched with the highly predacious Brazilian echinostome Paryphostomum segregatum, was dominated by the latter's predatory rediae. Pre-existing E. liei infections were destroyed, although the P. segregatum infection was itself delayed in development by an unidentified ‘indirect antagonism’ elicited by the E. liei larvae. In concurrent exposures with the two species, or with E. liei challenge of an established P. segregatum infection, the E. liei miracidia penetrated the snail, but the infection did not become established.
When E. liei and S. mansoni were paired, the former species dominated. Exposure of snails already infected with E. liei to miracidia of S. mansoni slowed growth of the latter and the schistosome sporocysts eventually disintegrated without producing cercariae. When E. liei miracidia were exposed to snails with S. mansoni infections of different ages, the echinostome became established but developed slowly. Subsequently, however, it destroyed the schistosome infection. Although E. liei is itself quickly eliminated by P. segregatum, the two species appear almost equal in anti-schistosome capacity. This can be credited in part to a deleterious or lethal effect of the E. liei-schistosome combination on the host snail, as well as to a direct anti-schistosomal effect. Greater knowledge of this host-inter-trematode balance may permit the use of trematodes to attack infected snails and their parasites in regions hyperendemic with human schistosomiasis.
Ultrastructural studies on microfilariae (Nematoda: Filarioidea)
Authors: McLaren Diane J.
Published: June 2009

The ultrastructural morphology of selected microfilariae from four genera is described and compared.
1. The sheath is composed of a thick layer of material not limited by membranes.
2. The cuticle is composed of a trilaminate membrane, a dense cortical layer and an inner fibrous layer. The outer leaflet of the trilaminate membrane is covered with a dense surface layer.
3. The hypodermis is formed of four components, and the outer membrane of each component is castellated.
4. Muscle cells are located in the four quadrants of the worm; each cell is divided into a contractile and a non-contractile region. Anterior muscle cells are probably involved in the movement of the hook.
5. A buccal capsule is situated at the anterior tip of the microfilaria; it is connected to the pharyngeal thead. The thread is already surrounded by the future oesophageal cells. It is not yet known whether these structures are functional in the microfilaria.
6. Three kinds of sensory organelle have been identified; they all contain modified cilia. The hook is associated with one of the amphids.
7. The excretory vesicle opens through a pore in the cuticle and is surrounded at its base by an elongate cell. The apparatus may possibly have an excretory, secretory or osmoregulatory function.
8. The inner body is composed of dense, granular material; it is already surrounded by the future intestinal cells. The inner body is thought to represent some kind of reserve material.
9. Apart from its size the G1 cell shows no unusual characteristics.
10. The anal vesicle opens through a pore in the cuticle and is surrounded at its base by the three R cells. The anal apparatus may be instrumental in the removal of waste materials, or it may be involved in some secretory activity.
Duration of immunity to East Coast fever (Theileria parva infection of cattle)
Authors: Burridge M. J. , Morzaria S. P. , Cunningham M. P. , Brown C. G. D.
Published: June 2009

Forty-five cattle, which had recovered from EOF and been kept free from reexposure to infection for periods of 1–43 months, were given a single uniform lethal challenge using a stabilate prepared from triturated infected ticks. All withstood the challenge which killed the five controls. There was an increase in the incidence of mild febrile reactions with time since last exposure to T. parva, indicating a gradual loss of immunity in the absence of reinfection. The duration of the immunity was not related to the severity of the initial reaction.

We are indebted to our colleagues on the Immunological Research on Tickborne Cattle Diseases and Tick Control Project, with whom we designed and carried out the experiment.
The distribution of Nippostrongylus brasiliensis in prolonged infections in lactating and neonatally infected rats
Authors: Connan R. M.
Published: June 2009

In lactating rats examined 3 weeks post infection, adult Nippostrongylus brasiliensis were found in the duodenum close to the pylorus. Worms migrated from the predilection site, shown by Brambell (1965) and Alphey (1970) to be approximately 25% down the intestine, during the second week of infection. A similar migration took place in neonatally infected rats.

It was suggested that the migration was an active response to immunological damage. It could be prevented by early betamethasone treatment but only modified by treatment given late in infection.
The egg envelopes of Polymorphus minutus (Acanthocephala)
Authors: Whitpield P. J.
Published: June 2009

The series of egg envelopes around the acanthor in the mature egg of the palaeacanthocephalan, Polymorphus minutus, has been investigated with light and electron microscopy. An attempt has been made to characterize the macromolecules from which the envelopes are constructed using histochemistry, an analysis of stabilizing bond types and comparisons of envelope fine structure with that of other structural protein systems.
The outermost envelope (I) of the mature Polymorphus egg is a fertilization membrane. It is produced by membrane-bounded inclusions in the cytoplasm of the unfertilized oocyte which discharge their contents into the extracellular space around the egg. Envelope II is composed largely of keratin, and its subzones consist of different packing arrangements of 8 nm diameter electron-lucid filaments in an electron-dense matrix. The electron microscopical appearances which this filamentous keratin can present due to section orientation artefacts are discussed. The innermost envelope (III) is 20–30 nm thick and highly corrugated. The spaces between envelopes I and II and between envelope III and the inner surface of envelope II contain material with a granular or fibrous ultrastructure. These spaces show histochemical evidence for the presence of acid mucopolysaccharides.
Extrinsic factors affecting the reproduction ofNippostrongylus brasiliensis
Authors: Phillipson R. F.
Published: June 2009

Experiments to study the effect of extrinsic factors on the copulation of normal adultNippostrongylus brasiliensisare described. Worms copulated when in contact with the rat small intestine, whether it was ligatured, maintained inside or outside the peritoneal cavity, slit open or its lumen obstructed, provided that the blood supply remained intact and the temperature was within a few degrees of normal. Copulation did not occur in the colon, pleural cavity, peritoneal cavity, pregnant or non-pregnant uterus of the live rat or under a variety ofin vitroconditions. These results indicate the importance of extrinsic factors for successful copulation since all the worms used in the experiments were intrinsically ready for immediate copulation in their normal environment. Worms observed duringin vitroexperiments were more vigorous and erratic in their movements than worms in their normal environment. The possible significance of this observation is discussed both in the context ofin vitroreproduction experiments andin vitroexperiments to study the physiology and biochemistry of the worm.
The functional organization and fine structure of the tail musculature of the cercariae of Cryptocotyle lingua and Himasthla secunda
Authors: Chapman H. D.
Published: June 2009

The functional organization of the tail musculature of two species of cercariae has been studied by examination of serial sections in the light and transmission electron microscopes. A three-dimensional reconstruction of the tail has been established. The fine structure of the muscle cells has been investigated and the complexity of organization is related to the requirement for a fast contracting system in the cercarial tail.
Surface aminopeptidase in Moniliformis dubius and its relation to amino acid uptake
Authors: Uglem Gray L. , Pappas Peter W. , Read Clark P.
Published: June 2009

Surface aminopeptidase (APase) in the acanthocephalan, Moniliformis dubius, was studied using leucylleucine, leucylglycylglycine, glycylglycine, alanylalanine, tri-alanine and tetra-alanine as substrates. In the presence of intact worms all peptides, except glycylglycine, were hydrolysed liberating amino acids and/or peptide subunits into the incubation medium. In 5 min incubations with 5mM leucylleucine, 93% of the liberated leucine was absorbed by the worms indicating a kinetic advantage for absorption of the leucine. In media with leucylleucine plus 10 mM methionine as an inhibitor of leucine uptake, the liberated leucine was not absorbed by the worms, but accumulated in the incubation medium.
The inhibitory effects of leucylleucine and alanylalanine (or products of hydrolysis) on the uptake of 0·1 mM [14C]leucine in 2 min incubations were examined. Inhibition of [14C]leucine uptake by these peptides was non-linear up to 5 mM inhibitor concentration. Concentrations of either peptide greater than 5 mM did not produce further inhibition. A significant portion of [14C]leucine transport was not inhibited by these peptides. Inclusion of 0·5 mM Pb2+, an APase inhibitor, blocked the inhibition of [14C]leucine uptake by leucylleucine indicating that the inhibition is caused by the liberated leucine alone, and that interaction of the intact dipeptide and the leucine transport system is negligible.
It is concluded that the surface membrane of adult worms has APase which can hydrolyse peptides in the ambient medium. The spatial arrangement of the APase and the leucine transport system is such that the hydrolysis of a peptide confers a kinetic advantage for absorption of the liberated amino acids.
Encysted or mechanically excysted cystacanth larvae from the haemocoele of the cockroach showed no APase activity. Activation of the APase required a 30 min treatment in lipase, [Na+]taurocholate or other surface active agents. Since the APase in adult worms was unaffected by washing, the data strongly suggest that this enzyme is of parasitic origin.
Studies on ascaridoid nematodes of pythons: two new species from New Guinea
Authors: Sprent J. F. A.
Published: June 2009

Two new species are described from New Guinea pythons, i.e. Ophidascaris niuginiensis and O. papuanus. The former was from Chondropython viridis and Liasis albertisi, the latter from L. amethistinus. Development of O. niuginiensis in mice involved a primary stage in the liver, a secondary stage in the mesenteric blood vessels and a tertiary stage in the skin, where growth occurred to a length of 50 mm or more. Initial growth, up to 10 mm, of O. papuanus occurred in the liver and body cavity of mice; a secondary growth phase occurred in the body cavity of the python host.
The incidence of Anoplocephaline cestodes in a population of rabbits in Surrey, England
Authors: Mead-Briggs A. R. , Vaughan J. A.
Published: June 2009

Samples of approximately five wild rabbits were obtained each week over the 4-year period 1967–70, and their intestines examined for adult tapeworms. Pour species of anoplocephalinae were found,Cittotaenia pectinata, C. denticulata, C. ctenoidesandAndrya cuniculi. C. pectinatawas found in 29% of the 968 rabbits examined,C. denticulatain 14%,C. ctenoidesin 12% andA. cuniculiin 6%. There were 63 double infections, of which 44 involvedA. cuniculi, and three triple infections. The most frequent number of worms per infection was one forC. pectinataandA. cuniculiand two forC. denticulataandC. clenoides, although the mean numbers for these species were respectively 7·2, 5·3, 2·7 and 1·8.A. cuniculi, and to a lesser extentC. ctenoides, were very restricted in distribution within the study area, occurring only on the higher, chalk downland (250–550 ft A.S.L.). This finding implies that individual rabbits usually spend their lives within relatively small areas. Considering all the material a seasonal trend in host infection rate was apparent only withC. denticulata, which increased in abundance from July to a peak in September and then declined gradually to a low level, lasting from April to June. Infections, including small specimens of any of the four species, were rare from February to June and it is presumed that infected intermediate hosts were correspondingly rare during this period. Except forC. denticulata, which was found more frequently in male rabbits than females, the sex of the host had no influence on its likelihood of infection. However, except forC. pectinata, the age of the host was important. Thus,C. denticulataandA. cuniculiwere significantly more frequent in juveniles than adults whilst the reverse was true forC. ctenoides. Small (‘young’) specimens ofC. denticulataandA. cuniculiwere more frequent in juvenile than adult rabbits, but the difference was not significant for the other two species. It is concluded that onlyC. ctenoidessurvives for more than a year and that this species andC. pectinataare more likely to infect rabbits that are adult than are the other two species.
Eimeria tenella: experimental studies on the development of resistance to amprolium, clopidol and methyl benzoquate
Authors: Chapman H. D.
Published: June 2009

The development of resistance by the Houghton strain of Eimeria tenella to the anticoccidial drugs amprolium, clopidol and methyl benzoquate has been studied. Resistance to amprolium and clopidol developed more readily in experiments where a large number of coccidia were exposed to the drug, either by increasing the number of oocysts in the inoculum or by increasing the number of birds in the group. When 45 birds were given 2·0 × 106 oocysts, resistance to amprolium and clopidol appeared after 6 and 7 passages respectively. In previous experiments, under similar conditions, resistance to robenidine developed after 6 passages, suggesting little difference between these three drugs. Resistance to amprolium and clopidol arose gradually as the concentration of drug was increased, but resistance to methyl benzoquate appeared in a single step from sensitivity to high-level resistance. Both amprolium and clopidol-resistant lines showed an 8-fold reduction in drug sensitivity. Attempts to measure the degree of resistance by calculation of the ED50 were unsuccessful.
Boophilus microplus: rejection of larvae from British breed cattle
Authors: Koudstaal D. , Kemp D. H. , Kerr J. D.
Published: June 2009

Larvae of Boophilus microplus were labelled with [32P] and used to study the rejection of larvae from British breed cattle with different levels of resistance. On animals of high resistance the loss of larvae due to grooming ranged from 9–54% during the first 24 h of infestation, and more time was spent grooming by these animals. Most of the grooming activity could be attributed to the presence of tick larvae and the presence of older tick stages did not increase the percentage of larvae lost. Grooming was directed to attached larvae and these could be removed. Animals of low resistance did not lose a significant number of larvae as a result of grooming, but all previously infested hosts lost a proportion of the larvae (18–39%) which could not be accounted for by grooming. This loss was greater than the total loss of larvae (11%) on animals not previously exposed to B. microplus.
The life-cycle, ultrastructure and mode of feeding of the locust amoeba Malpighamoeba locustae
Authors: Harry Owen G. , Finlayson L. H.
Published: June 2009

The primary trophozoites of Malpighamoeba locustae excyst in the crop and midgut of the Desert Locust (Schistocerca gregaria) and then penetrate the epithelial cells of the midgut and caeca where they grow and multiply slowly. After about 10–12 days they leave the gut epithelium passively when the cells in which they have grown degenerate and are extruded. From the lumen of the gut they make their way into the lumen of the Malpighian tubules where they feed upon the brush border as extracellular parasites. No primary or secondary trophozoites were found in the haemocoele of the host.

During the first few days in the Malpighian tubules the secondary trophozoites undergo a rapid series of divisions which enables them to double their numbers every 24 h so that by day 20–22 the lumen of the tubules is packed with cysts and trophozoites. The trophozoites phagocy-tose small pieces of brush border and numerous food vacuoles are present in their cytoplasm. The cytoplasm of the primary trophozoite contains the normal complement of cell organelles, a notable feature of which are the large, numerous mitochondria with their tubular cristae. When the trophozoites are ready to encyst they round up and begin to lay down a series of membranes which totally cover the trophozoite. Numerous storage granules are found in mature trophozoites which are about to encyst and these may be utilized in cyst wall production.
The role of the tegument of the metacercarial stage of Bucephalus haimeanus (Lacaze-Duthiers, 1854) in the absorption of particulate material and small molecules in solution
Authors: Higgins J. C.
Published: June 2009

Uptake by the tegument of metacercariae of Bucephalus haimeanus of both particulate material and small molecules in solution is demonstrated by the use of electron-dense tracers and autoradiographic techniques. Ruthenium red (RR) uptake involved pinocystosis and the formation of large, electron-lucent vesicles in the outer cytoplasmic tegument. RR lost its association with these vesicles and became freely dispersed within the cytoplasm as it passed through the outer cytoplasmic tegument, down the cytoplasmic bridges and into the tegumental cell bodies. Ferritin, iodinated insulin and iodinated human serum albumin were also located within the outer cytoplasmic tegument and ferritin collected beneath the inner plasma membrane of the outer cytoplasmic tegument. Horseradish peroxidase was not absorbed by the tegument although it bound strongly to the outer surface of the metacercariae. C-labelled glucose, phenylalanine, tryptophan and tyrosine were all detected in the outer cytoplasmic tegument.
Schistosoma mansoni: the activity and development of the schistosomulum during migration from the skin to the hepatic portal system
Authors: Wilson R. A. , Draskau Tove , Miller Patricia , Lawson J. Ruth
Published: June 2009

The activity patterns and changes in shape of schistosomula recovered from various locations during migration, are described. There is no significant increase in length during the period which worms remain in the skin. Rhythmic cycles of extension and contraction of the worm body are established soon after penetration. Worms newly arrived at the lungs are identical with skin worms of the same age. Within the lungs their maximum length increases to four times that of skin worms, an adaptation which is believed to facilitate migration through the lumina of blood capillaries. Worms recovered from the lungs and systemic organs on, and subsequent to, day 8 post-infection retain this capacity for elongation. When worms arrive at the hepatic portal system they undergo a process of shortening and there is a transient doubling in the duration of cycles of activity. It is suggested that this shape and activity change terminates migration by preventing escape of worms from the hepatic portal system via the liver sinuses. The stimulus which triggers the response is thought to be the high nutrient levels present in hepatic portal blood, but not in peripheral blood. The stimulus which terminates migration also probably initiates growth. Worms cultured in vitro undergo some increase in length, but have a significantly lower maximum length than lung worms of a corresponding age. Although cultured worms were active, the cycles of extension and contraction were much more erratic than those of in vivo worms. The worms shortened spontaneously after 8–10 days in culture. This shortening occurred marginally later than in the most rapidly migrating worms in vivo.
Use of genomic DNA restriction fragment length differences to identify nematode species
Authors: Curran J. , Baillie D. L. , Webster J. M.
Published: June 2009

Restriction endonuclease digestion of genomic DNA generates DNA fragments of unique size, dependent upon the particular base sequence. Following fractionation by agarose gel electrophoresis, repetitive DNA can be visualized as distinct bands in stained gels and the restriction fragment length of such bands used as diagnostic characters. Restriction fragment length differences were detected between species within the genera Trichinella, Caenorhabditis, Romanomermis, Steinernema (syn. Neoaplectana) and Meloidogyne. This technique provides a new tool for the taxonomist, which is independent of phenotypic variation and it enables the rapid and reliable separation of closely related species.
Development of the tegument and alimentary tract in a trematode, Fellodistomum fellis
Authors: Halton D. W. , McCrae J. M.
Published: June 2009

Formation of the tegument and alimentary tract in developing Fellodistomum fellis cercariae has been examined by electron microscopy. Morphogenesis of the tegument is a two-stage event: (1) ectodermal cells at the germ ball periphery coalesce beneath a closely apposed and transitory primitive epithelium of sporocyst origin, forming a syncytial boundary of nucleated tegument. The primitive epithelium is then lost and the nuclei in the surface layer of the early tegument degenerate; (2) cells in the mesenchyme of the cercarial embryo differentiate as secretory cells and connect with the anucleate layer to form the true tegument. The foregut develops as an apical invagination of early nucleated tegument, with the primordial digestive cells differentiating behind the oesophagus. When fully formed, the surface anucleate layer of oesophagus tegument extends posteriorly over the apposed surfaces of the developing digestive cells, thus isolating them from each other and from the gut lumen. An apical cavity develops in each of the digestive cells and later communicates with the gut lumen through a pore in the overlying caecal tegument. Lamellated extensions of digestive cell cytoplasm project into the cavity, and development of GER and a Golgi apparatus in the cell mark the onset of digestive secretion.
Biological controls in mixed trichostrongyle infections
Authors: Whitlock J. H. , Georgi J. R.
Published: June 2009

The parasite reaction phenotype of 80 lambs was determined with natural infection on pasture. These lambs were then assigned to outcome groups and randomized into treatment groups. Developing some simple but unusual analytical techniques it was possible to demonstrate that mixed natural infections of trichostrongyles with the chief biomass component Haemonchus contortus cayugensis protected against superinfections with 35000 infective larvae but protected against superinfections with 1000 infective larvae per day only within the limits characteristic of the enclosing barn ecosystem. The limits of the barn ecosystem were less constraining on more diathetic sheep than the natural pasture infection. Internal evidence from the experiment suggests that the interaction of sheep × pasture × infective trichostrongylid larvae constrains the parasite biomass in the host in more diathetic animals at significantly lower levels. Anaphylactoid ‘self-cure’ did not occur in this experiment but something like premunition certainly did.
Feeding ofBoophilus micropluslarvae on a partially defined medium through thin slices of cattle skin
Authors: Kemp D. H. , Koudstaal D. , Roberts J. A. , Kerr J. D.
Published: June 2009

Larvae of the cattle tickBoophilus micropluswill attach to thin (0·3–0·5 mm) slices of cattle skin and engorge on a partially denned medium at 35 °C. Forty-seven to 83% of the larvae had engorged by 8 days, and 51–71% of these moulted to nymphs. Tissue culture medium alone allowed little growth unless supplemented with dialysed, freeze dried bovine serum (7%, w/v). This medium could be further defined by substituting purified bovine serum albumin (Cohn fraction V) for the dialysed bovine serum. In one experiment, nymphs ofHaemaphysalis longicornisengorged and later moulted to adults. Skin slices were used fresh or after freeze-drying and storing at − 25 °C. The possible uses of the culture method are discussed.
Faecal egg counts and nematode fecundity: Heligmosomoides polygyrus and laboratory mice
Authors: Keymer A. E. , Hiorns R. W.
Published: June 2009

The results are presented of an experimental investigation of the relationship between faecal egg counts and worm burden in outbred MF1 mice infected with Heligmosomoides polygyrus (Nematoda). The sex-ratio of the adult parasites was found to be significantly female biased, but independent of parasite burden. Evidence was also found to suggest a significant association between parasite density and mating success. The linear logarithmic relationship (gradient of approximately 2) between the variance and mean of repeated egg counts from individual mice could not be disrupted by controlled experimental conditions, and is therefore concluded to be an inherent feature of the biology of helminth-host interactions. A significant positive association was detected between host faecal output and parasite fecundity; further investigation of the cause of this association is now required. Average faecal production was found to be inversely related to worm burden. In combination, the above two factors account partly, but not completely, for the observed density dependence in the absolute rate of parasite egg production. Two epidemiological consequences of the relationship between faecal production and parasite fecundity are discussed. First, absolute rates of egg production can only be estimated by temporal egg counts (epd). Secondly, measurements of egg production/g of faecal material (epg) are more reliable indicators of worm burden than measurements of epd. Both faecal output and worm fecundity respond as might be predicted to a period of host food deprivation; faecal egestion and measurements of epd are signifcantly depressed, and measurements of epg are significantly increased. The data are consistent with the hypothesis that egg production and faecal output are causally associated, but that other factors relating to parasite density also influence egg production. Of the possible causes for the high variability in parasite egg production between mice harbouring low number of worms, the most likely explanation seems to be host heterogeneity (possible genetic in origin). This is discussed in relation to similar patterns observed in data collected from human populations in areas of endemic helminth infection.
Parasite utilization of a host community: the distribution and occurrence of metacercarial cysts of Echinoparyphium recurvatum (Digenea: Echinostomatidae) in seven species of mollusc at Harting Pond, Sussex
Authors: Evans N. A. , Whitfield P. J. , Dobson A. P.
Published: June 2009

The occurrence, in September 1979, of Echinoparyphium recurvatum metacercarial cysts in a community of molluscan hosts at Harting Pond, West Sussex, was investigated. The parasite exhibited broad host specificity with all 7 species comprising the molluscan community being infected. There were marked differences, however, in the extent to which each host species was utilized and using the mean number of parasites/ individual mollusc as a parameter of infection the mollusc species may be ranked in descending order of utilization as follows: Sphaerium corneum, Lymnaea peregra, Valvata piscinalis, planorbids, Pisidium subtruncatum and Potamopyrgus jenkinsi. Combination of basic infection data with population estimates for each mollusc species in the study area showed that the bivalve P. subtruncatum and the prosobranch V. piscinalis were the most important hosts because they contained approximately 90% of the total number of cysts. In both of these hosts the cyst population was over-dispersed and the degree of over-dispersion increased with host size. The pattern of second intermediate host utilization is discussed in relation to the likely flow of E. recurvatum between the first intermediate host (L. peregra) and wildfowl definitive hosts at Harting.
Establishment and maintenance of behavioural dominance in male mice infected withTrichinella spiralis
Authors: Rau M. E.
Published: June 2009

Trichinella spiralis infections influenced the establishment and maintenance of behavioural dominance among outbred male mice. Infected animals assumed a subordinate status when challenged by normal or more lightly infected conspecifics both in an unfamiliar test arena and in their established home cages. These effects were demonstrable during the acute and the chronic phases of infection. The significance of this phenomenon to the survival of the mouse host and the transmission of the parasite is discussed.
Parthenogenesis and asexual multiplication among parasitic platyhelminths
Authors: Whitfield P. J. , Evans N. A.
Published: June 2009

Among flatworms with parasitic and commensal modes of existence, parthenogenesis and asexual multiplication appear to be largely confined to the Digenea and Cestoda, the only parasitic platyhelminths that routinely utilize indirect life-cycles. Parthenogenesis is apparently restricted to a minority of adult digeneans and cestodes inhabiting their final hosts, and a survey is made of the particular modes of parthenogenesis (i.e. apomictic, automictic and generative) which are employed by such adults. Asexual (amictic) multiplication, in the form of fissioning, is demonstrated by young adults of the cyclophyllidean cestode, Mesoces-toides corti, but is otherwise not exhibited by adult cestodes or digeneans, other than in the perplexing phenomenon of proglottid formation in polyzoic tapeworms. Secondary multiplication is of ubiquitous occurrence in digenean life-cycles in the form of the proliferation which takes place within sporocysts and rediae (germinal sacs) located in the first intermediate host. The controversy concerning the nature of this multiplication is reconsidered in the context of recent findings which have centred on cellular aspects. On the basis of present evidence germinal sac multiplication should be regarded as an asexual rather than a parthen-ogenetic process. The cestode asexual multiplication which occurs in intermediate hosts is a function of the metacestode stage of development. Metacestode proliferation is only known from about 20 species and 6 families of polyzoic cestodes with approximately half the described instances occurring in the family Taeniidae. The organization of these proliferative metacestodes, findings concerning their totipotent stem cells and the ontogeny of buds and new scolices are all reviewed. Finally, the capacity for population expansion of multiplicative larval digeneans and metacestodes are compared, while the ecological roles and the genetical consequences of both parthenogenesis and amictic multiplication in the two taxa are also examined.
The number and size of ovarian balls ofMoniliformis(Acanthocephala) from laboratory rats
Authors: Crompton D. W. T. , Arnold Susan , Walters D. E.
Published: June 2009

By means of conventional light microscopical and counting procedures, estimations have been made of the average number and size of ovarian balls from unfertilized and fertilized femaleMoniliformis dubius. The observations were made on worms recovered from experimental primary infections lasting 1, 2, 3, 4, 5, 8, 11, 14, 17 and 20 weeks in male rats. The number of ovarian balls rises to about 6300 per worm, with the maximum being attained more rapidly in unfertilized than in fertilized females. On average more ovarian balls were present in unfertilized than in fertilized females, but a marked decline in number occurred in both groups of worms towards the end of the experimental period. Similarly, on the basis of the area within the elliptical profiles of fixed ovarian balls, it appeared that those from unfertilized females were generally larger on average than those from fertilized worms.
Synchronization of Plasmodium falciparum gametocytes using an automated suspension culture system
Authors: Ponnudurai T. , Lensen A. H. W. , Meis J. F. G. M. , Meuwissen J. H. E. Th.
Published: June 2009

An automated suspension culture system for the cultivation of Plasmodium falciparum is described which retains a degree of flexibility which is absent in other automated culture apparatuses. Not only does this system of cultivation promote rapid multiplication of asexual parasites but also permits the development and maturation of gametocytes. Using a combination of gelatin flotation and N-acetyl glucosamine treatment synchronous development of gametocytes was achieved. The total time for gametocyte maturation in vitro under the conditions provided was 7 days. Stages II and V required 48 h for development whilst I, III and IV needed 24 h each. Mature microgametocytes were relatively long lived in comparison with macrogametocytes. Electron microscopic study of the synchronized stages confirmed the observations of Sinden (1982) but, in addition, we noted the presence of Garnham bodies, a cytostome in all stages and dense spherules in stages I–III similar to the fenestrated buttons in sporozoites and exoerythrocytic forms. The relationship between the number of osmiophilic bodies in the mature gametocytes and their ability to escape from the red cell is reaffirmed.