Moniliformis Dubius Research Articles

A child with an acanthocephalan infection

We herein describe a case of acanthocephalan infection in a 20-month old Saudi child who presented with a 3-month history of recurrent passage of long worms and poor appetite. The worm was misdiagnosed as Ascaris at another institution. Careful egg and worm examination confirmed the diagnosis of the acanthocephalan Moniliformis moniliformis. The child completely recovered with two courses of mebendazole, 3 days each, administered one week apart. Repeated stool analysis for 2-months post therapy confirmed complete eradication of this worm. We believe this is the first case of human acanthocephalan infection reported in Saudi Arabia.

Effects of concurrent infections on Hymenolepis diminuta (Cestoda) and Moniliformis dubius (Acanthocephala). I. General effects and comparison with crowding. 1961.

Hymenolepis diminuta developing in the presence of Moniliformis dubius are lighter, shorter, have a lower average weight:length ratio, and are limited to the posterior part of the intra-intestinal range they occupy in single infections. M. dubius in the concurrent infections are lighter, possibly shorter, have a lower average weight:length ratio, and tend to attach further anterior than in single infections. No effects were noted on the percent recovery of either helminth. Highly significant regressions of the wet weight, length, and weight:length ratio of H. diminuta and M. dubius on the number of larvae administered in single infections have been demonstrated. The weight and length of the H. diminuta, and the weight and weight:length ratios of the M. dubius, from concurrent infections were significantly lower than values predicted for single-species infections with a comparable number of worms. In crowded single-species infections, the distribution of attachment points of the H. diminuta is extended to include the anterior three-fourths of the intestine; in concurrent infections the tapeworms are limited to the posterior part of this range. Under crowded conditions, the M. dubius extend their linear intestinal distribution only slightly, all of the acanthocephalans attaching in the anterior half of the small intestine; in concurrent infections the acanthocephalans tend to be limited to the anterior part of this range. The distributional limitations in concurrent infections and the similarities between the effects of concurrent infection and crowding suggest that similar mechanisms, i.e., competition, possibly for carbohydrate, may be involved in the production of the effects of concurrent infection.

Comparative ultrastructural study of the lemnisci in larvae and adults of Centrorhynchus milvus Ward, 1956 (Acanthocephala, Centrorhynchidae)

The lemnisci of acanthocephalans are enigmatic organs which, except for those of adult Moniliformis dubius and Octospinifer macilentus, have not been described on the basis of examination by electron microscopy. We were able to study them in cystacanths, juveniles, and adults of Centrorhynchus milvus. They show a fibrous outer layer covering an amorphous layer; the latter is in close contact with a lining plasma membrane perforated by numerous pores which communicate with an equal number of small vesicles in cystacanths, with endocytotic vacuoles in juveniles, and with canaliculi in adults. In the center of each lemniscus are large nuclei surrounded by a common cytoplasm containing large protein granules. Only the lemnisci of cystacanths encysted in wood lice exhibit a large network of microfilaments at their center.

Morphological Studies on the Testis of Adults of Moniliformis (Acanthocephala)

AbstractThe morphology of the testis in young adult males of Moniliformis dubius developing in the rat has been studied with the aid of light and electron microscopes. In one‐day‐old male worms, the testis is organised as two zones. One zone consists of individual germ‐line cells, while the other consists of a supporting syncytium which embeds the cells and forms the boundary of the testis. The surface of the testis is covered by a fibrous non‐cytoplasmic coat. In seven‐day‐old male worms, the syncytium has lost its compact form, breaking down into multinucleate units connected by cytoplasmic processes and apparently forming a loose syncytial network throughout the testis. The germ cells are now randomly distributed and are surrounded by wide spaces among the segments of the supporting syncytium. The fibrous coat, lined internally by an irregular layer of the syncytium, forms the testis envelope. This basic structure is maintained in the testis of 14‐day‐old and sexually mature male worms.

Selective metabolism of L-serine by Moniliformis (Acanthocephala) in vitro.

In a series of in vitro experiments, adult male and female Moniliformis dubius were incubated at pH 6.88 and 37 degrees C for 3 h in a 2.5 mM solution of 18 amino acids. Fifteen of these were absorbed slightly from the medium, but L-serine was almost completely absorbed while the concentrations of glycine and alanine in the medium increased during the course of the incubation. By using L-[U-14C]serine, it was found that labelled ethanol and CO2 were the main end-products of metabolism excreted into the medium, with smaller amounts of labelled alanine, lactate and acetate. Small amounts of cystathionine with high specific radioactivity were found in extracts of the worms at the end of incubation, together with other radioactive metabolites including glucose, ethanol, lactate, succinate, malate, serine, glycine and alanine. Ammonia was found to be an excretory product of the amino acid metabolism of M. dubius. Possible metabolic pathways and suggestions for the significance of serine metabolism in this parasite are discussed.

Investigating over-dispersion; Moniliformis (Acanthocephala) and rats

An analysis of the frequency distribution of numbers of Moniliformis dubius in rats of an outbred strain of Wistar origin (CFHB) and feeding ad libitum on Oxoid 41B diet, showed that over-dispersion occurred regardless of the age and sex of the rats and the infective dose given (12, 20 or 40 cystacanths/rat). Over-dispersion was also shown to be independent of variability in the age and sex of the cystacanths given. The analysis demonstrated that the over-dispersion declined as the course of the infection proceeded. As expected, parasite survival was found to be age-dependent with female worms living longer, on average, than males, and both male and female worms living longer in rats given 12 as opposed to 20 cystacanths. Possible mechanisms for generating the over-dispersion observed during this work are discussed and a tentative hypothesis, invoking host heterogeneity with regard to carbohydrate availability in the small intestine, is proposed for further experimental investigation.

Interactions betweenMoniliformis(Acanthocephala) andNippostrongylus(Nematoda) in the small intestine of laboratory rats

Rats harbouring a 35-day-old primary infection of Moniliformis dubius were inoculated with constant doses of Nippostrongylus brasiliensis and 10 days later, after post mortem examination, rats with concurrent infections harboured significantly fewer Nippostrongylus than rats with single infections. Similar infections of Moniliformis were carried out, but with post mortem taking place on days 8, 9, 12 and 14 of the Nippostrongylus infections. On days 8 and 9 of infection, rats with concurrent infections did not harbour significantly fewer Nippostrongylus compared with single infections. Both single and concurrent infections of 12- and 14-day-old Nippostrongylus were found to harbour lower numbers of worms. In the single infection this corresponds to the timing of the typical immune expulsion of a primary single infection which takes place on approximately day 12 of infection. The Moniliformis population was not significantly affected, in terms of numbers, dry weight and length, although each parasite population did show a slight shift in site in the presence of the other. A significant reduction in egg production by Nippostrongylus was detected throughout concurrent infection. The possible role of non-reciprocal cross-immunity is discussed as an explanation for the apparent early expulsion of the Nippostrongylus population in the presence of Moniliformis.

Parasite population biology and host nutrition: dietary fructose and Moniliformis (Acanthocephala).

Experiments were carried out to investigate the possible influence of host-dietary fructose concentration on the relationship between worm burden and the fecundity of Moniliformis dubius. Worm length was found to be dependent both on the fructose concentration of the host's diet and on worm burden. The number of free ovaries/female worm was found to increase linearly with increasing dietary fructose concentration but was independent of worm burden. The length of the ovaries increased with increasing dietary fructose concentration and decreased in response to increases in worm density. The magnitude of the density-dependent reduction in the volume of ovarian tissue/female was decreased in worms from rats fed on diets containing low concentrations of fructose. The numbers of eggs present in the body cavities of the female worms was found to be positively correlated with dietary fructose concentration. At 5 weeks post-infection, mature eggs (containing fully developed acanthor larvae) were found in the body cavities of female worms from rats whose diets contained 3 and 12% fructose, but not in those from rats whose diets contained 1 and 2% fructose (w/w). The experimental results are discussed in the wider context of the influence of host nutrition on parasite population biology.

Aminergic neurons in the anterior nervous system of the rat acanthocephalan Moniliformis dubius.

The cerebral ganglion and nerve tracts of Moniliformis dubius show intense, specific, green fluorescence that is also associated with the lateral and apical sensory bulbs. Radioenzymatic assays showed that high levels of dopamine were present but only small amounts of the catecholamines norepinephrine and epinephrine were identified. Incubations of the proboscis sac in dilute solutions of dopamine increased fluorescence while incubations in reserpine resulted in loss of fluorescence. Nonfluorogenic amine octopamine was also detected radioenzymatically. Neutral red vitally stained a number of cells in the cerebral ganglion and the nerve tracts extending from the ganglion. Electron microscopy showed that many neurons contained electron-dense vesicles. The close association of the fluorescing, amine-containing nerve tracts with the sensory bulbs suggests that they may play a functional role in sensory reception and transmission in M. dubius. This is the first report on the presence of biogenic amines in the Acanthocephala.

Mucosal lesions in the rat associated with the attachment of Moniliformis (Acanthocephala).

By means of scanning electron microscopy, aspects of the attachment of Moniliformis dubius (Acanthocephala) to the intestinal wall of the rat are described together with various changes in the structure and form of the mucosa. Attachment of the parasite results in the formation of a distinct pit around the everted proboscis and a crater around the neck. Contact between the anterior region of the trunk of the worm and the intestine of the host appears to lead to villous fusion so that characteristic grooves are formed in the mucosal tissue. Evidence was also obtained to suggest that host goblet cells may become exhausted during the course of an infection with Moniliformis.

Rat-dietary fructose and the intestinal distribution and growth of Moniliformis (Acanthocephala).

The numbers, distribution in the small intestine, sexual development and growth (dry weight) of 5-week-old Moniliformis dubius (Acanthocephala) were investigated experimentally in adult, female CFHB rats fed on theoretically isoenergetic diets containing known amounts of fructose in combination with either maize-oil fatty acids or maize oil and two concentrations of casein. There was no obvious development of M. dubius when there was no fructose in the host's diet. In contrast, estimated consumption by the host of as little as about 2 g of fructose during the 5-week infection period was accompanied by marked sexual dimorphism and weight gain in most of the M. dubius present. The dry weights of M. dubius of both sexes were positively correlated with fructose concentrations ranging from 0 to 2.5% (w/w) in the diets containing fatty acids. Significant, but not substantial, increases in M. dubius dry weight were observed as the dietary fructose concentration was raised to 12% (w/w). Similar trends were observed when the fructose was offered to the infected rats with maize oil, but in general, fructose added to the fatty-acid based diets supported most M. dubius growth. Differences in the distribution pattern of the worms in rats fed on the fatty-acid or maize-oil based diets were observed and their possible significance is discussed.

Increase in size of the small intestine of rats infected with Moniliformis (Acanthocephala)

Singhvi A. and Crompton D. W. T. 1982. Increase in size of the small intestine of rats infected with Moniliformis (Acanthocephala). International Journal for Parasitology 12: 173–178. The size and histology of the small intestines of rats which had been infected for 6 weeks with a primary infection of not more than 40 Moniliformis dubius were compared with those of similar uninfected rats. Three significant differences were detected. The average length was greater, the average dry weight was heavier and the average dry weight per unit length was also heavier in infected than in uninfected rats. The increase in intestinal tissue may be accounted for mainly as the result of an increase in thickness of the muscle layers.

Effects of host dietary fructose on experimentally stunted Moniliformis (Acanthocephala)

Crompton D. W. T., Singhvi A. and Keymer Anne. 1982. Effects of host dietary fructose on experimentally stunted Moniliformis (Acanthocephala). International Journal for Parasitology 12: 117–121. Experimentally stunted Moniliformis dubius were obtained by allowing their hosts to feed on a purified synthetic diet containing 3 % glucose (w/w). Aspects of the growth, as measured by dry weight, and population dynamics of stunted Moniliformis aged 5, 7, 9, 11 and 14 weeks were compared with those of Moniliformis which were recovered from similar rats that had been allowed to feed for 3 weeks at particular times on an isoenergetic diet containing 3 % fructose. The rats that were given the fructose diet had eaten only the 3 % glucose diet and harboured infections of Moniliformis aged 5, 7, 9 and 11 weeks when the dietary change was made. It was found that the change of the host diet to one containing fructose promoted the growth and sexual development of the Moniliformis and increased their life spans. Some worms, however, were able to grow in the rats that continued to feed on the diet containing 3 % glucose. The possible significance of naturally stunted Moniliformis in the life cycle of the parasite is discussed.

Competition for dietary fructose between Moniliformis (acanthocephala) and growing rats

Crompton D. W. T., Singhvi A., Nesheim M. C. and Walters D. E. 1981. Competition for dietary fructose between Moniliformis (Acanthocephala) and growing rats. International journal for Parasitology 11: 457–461. The food intake, weight gain and blood sugar of young rats, fed on diets containing growth-limiting amounts of fructose and infected with Moniliformis dubius (Acanthocephala) for 6 weeks, were measured and compared with values obtained from similar uninfected rats which had been treated in the same manner. The growth of the rats was closely related to the fructose content of the diet. However, on average, the infected rats gained less weight than their uninfected counterparts. Significant differences between the values for blood sugar from infected and uninfected rats were not detected when the diet contained 2% fructose. The blood sugar of infected rats fed on a diet containing 4% fructose was found to be significantly less than that of similar uninfected rats. Information was also obtained about the numbers, sex, dry weight and location of the Moniliformis in the small intestines of their hosts. Male and female Moniliformis from rats fed on the 4% fructose diet were found to be heavier than those from rats fed on the 2% fructose diet. The results can be interpreted to suggest that the reduction in the growth rate of the infected rats is due to competition for fructose between Moniliformis and the rat.

A study of phosphoenolpyruvate carboxykinase from Moniliformis dubius (Acanthocephala).

Procedures have been developed for the extraction and subsequent purification of the enzyme phosphoenolpyruvate carboxykinase (GTP) (PEPCK) from Moniliformis dubius (Acanthocephala), a parasite of the rat small intestine. This is believed to be the first purification of PEPCK from an invertebrate animal. The enzyme, when purified to homogeneity as indicated by electrophoretic criteria, has a molecular weight of 73 700. Kinetic studies indicated that the enzyme had a pH optimum of 5.5 and required Mn2+ as the divalent cation. The apparent Km values determined for the substrates of the carboxylation reaction were low compared with the published values for purified PEPCK from vertebrate sources. Several competitive inhibitors were found and their Ki values determined. The possible regulation of PEPCK activity in M. dubius is discussed with reference to the observed kinetic parameters.

Observations on the surface morphology of the ovarian balls of Moniliformis (Acanthocephala).

The surface morphology of fixed ovarian balls from female Moniliformis dubius, agd 12, 18, 26, 28, 42, 77, 105 and 118 days, has been examined by means of scanning electron microscopy. The appearance of the surface has been found to be variable between ovarian balls from worms of the same and different ages. Some parts of the surface are seen to possess micro-projections, cavities and ridges while other parts have the appearance of an irregular meshwork of fibres. Various protruding features have been observed to extend from the surfaces of the ovarian balls taken from the inseminated female worms. In most cases, the surfaces of the protruding features differ in appearance from the surrounding surfaces of the ovarian balls. Some of these features have been assumed to represent growing zygotes and developing eggs covered by the supporting syncytium of the ovarian ball. Single or several thread-like structures have been observed in association with the surfaces of ovarian balls taken from the inseminated female worms. At present, the thread-like structures are believed to be portions of spermatozoa. By means of light microscopy, preliminary observations have been made on what is considered to be the division process of ovarian balls taken from uninseminated and inseminated worms varying in age from 7 to 98 days.

Evasion of the insect immune response by Moniliformis dubius(Acanthocephala): further observations on the origin of the envelope

The envelope around larvae of Moniliformis dubius appears to protect the parasite against immune recognition and encapsulation by the insect host's haemocytes. The origin of this envelope has been the subject of controversy although most evidence suggests it is parasite-derived. If host-derived, the envelope would be expected to share surface properties with host tissue. Thus, experiments were undertaken, transplanting parasites and host tissue to other insects and using haemocytic encapsulation as an assay for immune recognition, in order to compare the response to host tissue and to the parasite's envelope. Parasites without their envelopes, and pieces of tissue (ventral nerve cord) from the experimental host (the locust Schistocerca gregaria) were recognized as foreign and encapsulated in the cockroach, Periplaneta americana. The majority of parasites with their envelopes were unencapsulated or only partially encapsulated on transfer to their normal host, P. americana, indicating that the envelope does not have surface similarity to locust tissue. Cockroach-derived parasites with or without envelopes were not encapsulated in S. gregaria, suggesting that the larva itself can evade or inhibit the locust's recognition mechanism. However, since larvae which develop in S. gregaria are enclosed in an envelope, the formation of the envelope would seem to be an inherent feature of the parasite's development.

Net fluxes of electrolytes in the rat intestine infected with Moniliformis dubius (Acanthocephala).

The effect of Moniliformis dubius on fluxes of Na+, K+, Cl-, and HCO3-in the rat intestine was determined using a conventional in vivo single-pass perfusion technique. Results for ion and water movements in the uninfected gut were in agreement with previous studies. In the parasitized intestine the jejunal pH was significantly lower than that in control animals, matching the restriction of the parasites to this region of the small intestine. While parasitism did not affect Na+ transport in the distal ileum, Na+ absorption was reduced (pH 7.0), or secretion enhanced (pH 6.0), in the two proximal regions. Cl-absorption was reduced in the distal ileum, but secretion was enhanced in the other two segments. Parasitism also enhanced K+ secretion in all segments. Net H2O absorption was reduced at pH 7.0; at pH 7.0; at pH 6.0 net secretion was also reduced. These changes clearly indicate that a parasite restricted to the jejunum may significantly affect the absorptive and secretory activity of the intestine distal to the site of infection. The results are discussed in the light of current concepts of electrolyte transport. The effect of the parasites on mucosal function distal to their site of attachment is discussed in terms of the release by the parasite of toxin-like substances, changes in the physical-chemical characteristics of the intestinal lumen, and interference with neurohormonal control of gastrointestinal function.

Carbohydrate Transport in Moniliformis dubius (Acanthocephala). III. Post-Absorptive Fate of Fructose, Mannose, and Galactose

The initial metabolism of fructose, mannose, and galactose in Moniliformis dubius (M. moniliformis; Acanthocephala) was examined following brief aerobic incubations in 14C-labeled substrate. The pattern of incorporation of radioactivity from 14C-fructose and 14C-mannose into intermediates of hexose metabolism was indistinguishable from that reported elsewhere for the initial post-absorptive metabolism of 14C-glucose under comparable conditions; these hexoses were phosphorylated rapidly following their absorption, and much of the radioactivity absorbed as mannose or fructose was recovered in the nonreducing disaccharide trehalose [alpha-D-glucopyranosyl-(1 leads to 1)-alpha-D-glucopyranoside]. 14C-Galactose was phosphorylated less readily than the other hexoses. More than half of the radioactivity absorbed as galactose was incorporated into disaccharide; some of the galactose-derived disaccharide had properties suggesting the presence of a galactosyl moiety. Incorporation of radioactivity from any of the hexoses into glycogen was minimal. The extensive incorporation of hexose moieties into trehalose or a trehalose-like disaccharide rather than glycogen underscores the probable importance of trehalose metabolism to carbohydrate assimilation in Moniliformis. Physiological factors which might favor trehalose biosynthesis over glycogenesis are considered.

The number and size of ovarian balls ofMoniliformis(Acanthocephala) from laboratory rats

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 female Moniliformis 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.