Nippostrongylus brasiliensis infections in mice: the immunological basis of worm expulsion.

Nippostrongylus brasiliensis infections in mice were terminated more rapidly than in rats and immunologically induced damage occurred earlier. Like rats, mice expelled damaged worms more rapidly than normal worms. Recipients of cells from the spleen or mesenteric node of immune mice expelled their worms by day 8 of the infection. Recipients of cells alone or antiserum alone did not expel their worms by day 5 but mice given both cells and antiserum expelled their worms by this stage of the infection. Damaged worms were expelled more rapidly than normal worms from mice given immune cells, This work indicated that antibodies and cells collaborate to expel N. brasiliensis from mice as has been shown to occur in rats.     

Distribution, behavior, and course of patency of Dracunculus insignis in experimentally infected ferrets

From 106 ferrets experimentally infected with Dracunculus insignis, 273 female worms and 42 male worms were recovered. The percentage of female worms that mated, the location of all worms, and the rate of emergence of gravid females were recorded. Of 174 mature female worms recovered, only 11% had emerged before necropsy. Eighty-one percent of the male worms and 87% of all unmated (immature) females were found on the trunk of the animal or on the skin overlying it. Gravid female worms were found on the extremities (legs) 88% of the time. Almost one-third of gravid female worms were found on the left front leg. On 4 occasions, females were found in unusual locations: the tail, the cheek, the lumbar region of the spinal cord, and the peritoneal cavity associated with the omentum. The results showed that only a small percentage of mature female worms emerge, which suggests that infected persons harbor many more gravid female worms than indicated by reports of emergent worms. More than one-third of female worms were not mated, but it is likely that these immature females would be capable of further development. Furthermore, male worms have been observed to survive for up to 330 days, suggesting that male or unmated female worms may carry over from one transmission season to the next.     

Changes in behaviour associated with pair formation in the polychaete Harmothoë imbricata (L.)

Spacing between individuals in populations of Harmothoë imbricata has been investigated both on the shore and in the laboratory. Males tend to occur closer together than females, and the mean male‐male individual distance measured was less than the mean distance between females; male—female distances for immature worms were intermediate. When worms mature they pair: the male mounts the female and lies across her dorsal surface. There is evidence that after spawning the members of a pair separate. Contact responses between worms have been investigated in the laboratory. Most encounters between immature worms lead to separation, as a result of one or both worms moving rapidly away from the other or fighting; females show more marked avoidance behaviour than males. The majority of male‐male and female‐female encounters between mature worms also lead to separation but in male‐female encounters the male usually mounts the female. A male which has mounted a female becomes highly aggressive and will attack intruding males but not females.     

Dracunculus insignis: experimental infection in the ferret, Mustela putorius furo

The laboratory study of dracunculiasis has suffered from the lack of a suitable, readily available animal model. We have been able to experimentally infect ferrets. Mustela putorius furo, with the North American dracunculid, Dracunculus insignis. Ferrets were inoculated with 75 to 100 infective larvae and were necropsied 90 to 240 days later. Guinea worms were recovered from 10 (56%) of 18 ferrets. A total of 44 worms were recovered, for an average of 4.4 worms per infected ferret. Gravid female worms were recovered as early as 128 days postinoculation. Thirteen (87%) of 15 gravid female worms were recovered from the extremities. Living male worms were recovered at 200 days of age, indicating that not all male worms die shortly after mating. First-stage larvae recovered from gravid females as early as 200 days of age were found to be infective to the copepod, Acanthocyclops vernalis. These observations suggest that the ferret is an excellent laboratory animal for dracunculiasis research.     

Tolerance and biomarkers as useful tools for assessing environmental quality in the Oued Souss estuary (Bay of Agadir, Morocco)

The aim of this study was to assess aquatic environmental quality of Oued Souss (Agadir, Morocco). This estuary has been subjected for a long time to large amounts of sewage discharges and industrial effluents. Since November 2002, no waste outlets have been discharged in this site due to their connection to a wastewater purification plant. Firstly, we have compared metal tolerance of the annelid polychaete (Nereis diversicolor) originating from Oued Souss and a relatively clean site (Oualidia, Morocco). Secondly, we have evaluated with a multi-marker approach (acetylcholinesterase [AChE], glutathione-S-transferases [GSTs], catalase, thiobarbituric acid reactive substances [TBARs]) responses of worms to the pollution gradient. Results have shown that worms from Oued Souss have acquired tolerance to copper and zinc due to a long-term sub-lethal metal exposure and this metal tolerance was maintained in spite of the end of wastewater discharges in this site. Higher catalase, GSTs and TBARs values have been observed in worms from Oued Souss sampled before implantation of wastewater treatment. The multi-marker approach confirms that these worms have been submitted to various contaminants. In contrast, high inhibition in AChE activities measured in worms from Oued Souss could be explained by the continuous agricultural influence of nearest areas. The level of contamination was probably maintained since biomarker values were generally higher in worms from Oued Souss when compared to Oualidia.     

Lineus as a model for studying developmental processes in animals reconstructed from adult pieces

The difficulties that prevent reconstruction of animals by piecing together body fragments from several adults are overcome by using nemerteans of the genus Lineus. For 25 years I have managed to make viable composite worms by grafting body parts cut out of Lineus specimens either from the same clonal strain (syngeneically reconstructed worms) or from the same species (allogeneically reconstructed worms) or else from different species (xenogeneically reconstructed worms). Body reconstruction has usually been carried out orthotopically, i.e., the components of composite animals have been selected so as to be anatomically complementary. However, reconstruction has been made heterotopically when it was essential to obtain morphogenetic events in the adults. Here, I shall review some of the developmental processes that took place in such reconstructed animals. First, I shall report immune responses in composite worms derived from various combinations of body pieces grafted together. Second, I shall study sex differentiation during gonad development in growing or regenerating chimeric worms made by the grafting of male and female components. I shall refer also to gonadogenesis in the asexual progeny of bipartite chimeras derived from lateral body halves of both sexes fused together (clones of bilaterally allophenic worms). Third, I shall analyze regulative processes (regeneration, transgeneration) during localized morphogenesis occurring in heterotopically reconstructed worms. The data show how reconstructed Lineus may be exploited to increase our knowledge of developmental mechanisms, especially in the misunderstood field of organismal pattern homeostasis.     

Schistosoma mansoni: Electron probe X-ray microanalysis of the elemental composition of the tegument and subtegumental tissues of adult worms

The elementary composition [Na, Mg, P, S, Cl, K, Ca and Fe] of the tegument, tegumental spines, and subtegumental tissues of adult male and female Schistosoma mansoni have been determined by electron probe X-ray microanalysis of unfixed, freeze-dried cryosections. Statistical analysis of the results suggests that there are distinct differences in the elemental composition of the tissues both between and within individual male and female worms, and between male and female worms in general. In particular, there were significant variations in the elemental contents of the tissues between individual male and female worms, which may reflect differences in the physiology and/or metabolic state of the worms. Significant differences in the elemental composition of the various tissues examined within individual worms were also found. In general, in both male and female worms, there were significantly higher elemental levels in the tegument, as opposed to the subtegumental tissues. The elemental composition of the tegumental spines in both male and female worms differed from that of the tegumental cytoplasm, although the differences in the elemental composition between spines from male and female worms reflected the differences in the elemental content between the teguments themselves. Differences in the elemental composition of the tissues between male and female worms were also found, with the female tegument containing significantly higher elemental levels (with the exception of Cl) than the male tegument. In particular, the tegument of female worms contained higher levels of calcium and, in relatively small areas, isolated calcium-containing granules. This higher tegumental calcium level in female worms may reflect a higher calcium demand by sexually mature female worms due to the presence, within the mature vitelline cells, of calcium-containing corpuscles and the production of large numbers of eggs.     

The influence of Nematospiroides dubius on subsequent Nippostrongylus brasiliensis infections in mice.

The fecundity and longevity of Nippostrongylus brasiliensis was prolonged in mice previously infected with Nematospiroides dubius only when the former developed from the larval stage in those mice. Such worms appeared to be less immunogenic than worms which developed in mice never exposed to N. dubius. It is proposed that prolonged fecundity and longevity resulted from an adaptation undertaken by the worms in the face of host antibodies which had been developed against the pre-existing N. dubius infection.     

Strategies for the storage of Ancylostoma caninum third-stage larvae

Although cryopreservation protocols for storage of hookworm larvae have been described, the circumstances under which the technique is necessary to ensure larval survival are not well defined. The motility of infective-stage larvae (as judged by observation) and their ability to migrate through canine skin in vitro were measured over a 7-mo period in worms held at room temperature and worms that had been cryopreserved at the start of the experiment. Cryopreserved worms showed motility and migration proportions of 45.6-48.0% and 26.8- 34.0%, respectively, throughout the experiment, compared with percentages of 92.7 and 84.1%, respectively, in the original fresh worms. Larvae held at room temperature showed a gradual decrease in motility and migration ability over the experimental period. Motility and migratory ability of cryopreserved larvae was only significantly higher (P < 0.01) than room temperature-stored larvae from 4 and 5 mo onward, respectively.     

The ability of cestodes to synthesize serotonin

The ability of the parasitic flat worms Hymenolepis diminuta and Mesocestoides corti to synthetize serotonin (5-HT) has been investigated by means of incubation the worms in metabolic precursor of 5-HT, L-tryptophan, and monoamineoxidase inhibitor, indopan, followed by spectrofluorimetric determination of the tissue level of 5-HT. To avoid possible inhibition of 5-HT synthesis by exogenous 5-HT of the host, experiments were carried out on worms in which the level of 5-HT was previously decreased by reserpine. The increase in the level of 5-HT in tissues after incubation of the worms in L-tryptophan and indopan was observed, indicating their ability to synthetize serotonin from tryptophan.     

Grunting for worms: seismic vibrations cause Diplocardia earthworms to emerge from the soil

Harvesting earthworms by a practice called 'worm grunting' is a widespread and profitable business in the southeastern USA. Although a variety of techniques are used, most involve rhythmically scraping a wooden stake driven into the ground, with a flat metal object. A common assumption is that vibrations cause the worms to surface, but this phenomenon has not been studied experimentally. We demonstrate that Diplocardia earthworms emerge from the soil within minutes following the onset of grunting. Broadband low frequency (below 500 Hz) pulsed vibrations were present in the soil throughout the area where worms were harvested, and the number of worms emerging decreased as the seismic signal decayed over distance. The findings are discussed in relation to two hypotheses: that worms are escaping vibrations caused by digging foragers and that worms are surfacing in response to vibrations caused by falling rain.     

Dissociation of the protective immune response in the mouse to Strongyloides ratti

The generation of protective immunity by various stages in the life-cycle of Strongyloides ratti and the phases against which resistance is directed has been examined in murine strongyloidiasis. Mice were exposed to natural, complete infections, were treated with thiabendazole (which largely resembles the natural infection), were treated with cambendazole (which restricts infection to the larval stage), or infected directly by oral transfer of adult worms. Mice that were infected with infective larvae alone did not become resistant to infective larvae or the complete infection but were resistant to adult worms implanted directly into the gut. Mice exposed to adult worms alone were resistant to natural infections and adults worms implanted directly but were not resistant to infective larvae. On the other hand, mice that had received prior natural infections showed evidence of resistance to infective larvae, adult worms, and natural, complete infections. It is concluded that there is immunological cross-reactivity between infective larvae and adult worms but that under certain circumstances the infective larvae are able to evade the host's protective immune response.     

Morphological and histochemical studies on the prostate gland of developing and adult Paramphistomum cervi (Digenea: Paramphistomatidae)

Morphological and histochemical studies have been made on the development of the prostate gland of the digenetic trematode, Paramphistomum cervi during the course of its infection in sheep; histochemical characterization of prostate gland secretion in adult worms and its functional relationship with the transport of spermatozoa have also been studied. In 6-wk-old worms, the terminal portion of the male genital duct is formed of what appears to be a syncytial epithelium containing a relatively large number of nuclei compared to the rest of the male duct. Cellular organization of the prostate gland becomes conspicuous in 8-wk-old worms and the prostate gland is fully developed by 16 wk. Two types of prostate gland cells, characteristic of the adult, become distinct in 16-wk-old worms which contain spermatozoa in the lumen of their vas deferens and pars prostatica. Adult worms show two types of prostate gland cells: type I containing mainly glycoprotein and type II mainly phospholipid granules. Weak-to-strong activities of acid phosphatase, alkaline phosphatase, esterase, lipase, adenosine triphosphatase, tetrazolium reductase, NAD-diaphorase, isocitrate dehydrogenase, glyceraldehyde dehydrogenase, α-glycerophosphate dehydrogenase and glucose-6-phosphate dehydrogenase have been observed in the prostate gland. The release of prostate gland secretion and the passage of spermatozoa through the lumen of pars prostatica appear to be synchronized events.     

Trichinella spiralis: role of non-H-2 genes in resistance to primary infection in mice

Two strains of mice which share identical H-2 genes but differ in their genetic backgrounds were compared for their ability to resist infection with Trichinella spiralis. The two strains of mice, C3HeB/FeJ and AKR/J, share the H-2k haplotype which is associated with susceptibility to primary infection with T. spiralis in H-2 congenic strains of mice. AKR/J mice, infected with 150 infective muscle larvae, harbored significantly fewer muscle larvae 30 days postinfection than did mice of the strain C3HeB/FeJ. Approximately equal numbers of worms establish in the small intestine of AKR and C3H mice, but the AKR mice expelled adult worms from the gut more rapidly than did mice of the C3H strain. By Day 9 postinfection, 50% of the worms had been expelled by the AKR mice whereas expulsion of worms from C3H mice was delayed beyond Day 9 and occurred primarily between Days 10 and 12. Over this same experimental period (Days 6-12), fecundity of female worms from AKR mice, measured as the mean newborn larvae/female/hour, was approximately one-half that of worms taken from C3H mice. These results support the conclusion that genes outside of the mouse H-2 complex regulate expulsion of adult worms from the gut. These background genes also markedly influence the fecundity of female worms.     

The length of Ostertagia ostertagi in populations of uniform age

Michel J. F., Lancaster M. B. and Hong C. 1978. The length of Ostertagia ostertagi in populations of uniform age. International Journal for Parasitology8: 437–441. The conclusion that, in calves exposed to daily infection with larvae of Ostertagia ostertagi, adult worms are constantly lost and replaced was based, in part, on the observation that the length of the worms present decreased with time. The underlying assumption that worms do not shrink was examined in an experiment in which groups of calves received 8300, 25,000 and 75,000 larvae respectively in a single occasion and were killed at various times between the 20th and 132nd day thereafter.The length of the worms was inversely related to the initial worm burden but as worm burdens declined the worms did not grow. Instead, in the groups that received 25,000 and 75,000 larvae, decreases in worm length of 7% and 8% respectively were seen when most of the worms had been lost. Although it appears very probable that this was due to the more rapid loss of large worms than of small, the point could not be conclusively demonstrated.     

Adult worm tegumental damage and egg-granulomas in praziquantel-resistant and -susceptible Schistosoma mansoni treated in vivo

The effect of treatment with praziquantel (PZQ) on the tegument of adult Schistosoma mansoni worms and on liver egg-granulomas has been examined in mice infected with PZQ-resistant and -susceptible parasite isolates. Two PZQ-resistant S. mansoni isolates, one selected by passage in the laboratory under drug pressure and one from Senegal established from eggs excreted by an uncured patient, were compared with PZQ-susceptible control isolates. Scanning electron microscopic observations on the tegument of Schistosoma adult worms treated in vivo with PZQ showed that more severe damage was inflicted by PZQ on susceptible worms than on drug-resistant worms. Observations on the pathology of Schistosoma egg-granulomas in the liver of infected mice after treatment with PZQ indicated that eggs from susceptible control isolates were more sensitive to PZQ than those from drug-resistant isolates.     

Oil decontamination of bottom sediments using <Emphasis Type="Italic">Limnodrilus hoffmeisteri</Emphasis> (Oligochaeta: Tubificidae)

Using aquatic worms (Oligochaeta: Tubificidae) for oil decontamination of bottom sediments has been first considered. In a set of experiments on Limnodrilus hoffmeisteri Claparede, 1862, worms survived the exposure to oil content as high as 16.72 g/kg; they died of natural causes. Vigorous silt agitation by worms (bioturbation) was observed: the silt layer thickened as compared with that in reference aquaria without worms. Besides, it tended to thicken with increasing oil content of sediments. Within 30 days Limnodrilus hoffmeisteri reduced oil content by 1.20 to 1.72 times, or by 16.67 to 41.90% (a<0.05), compared with that in reference aquaria.     

Trichinella spiralis: an intracellular parasite in the intestinal phase.

Trichinella spiralis has been examined by electron microscopy after fixation in situ in the intestine of mice. The worms lie within the cytoplasm of cells of the intestinal mucosa and may occupy both absorptive and goblet cells. They cause little damage to host cells. A few worms have been seen protruding from tissue by SEM techniques. These unusual observations suggest that the nematodes may be capable of exit and reentry into the epithelium.     

Trichinella spiralis: immunity and inflammation in the expulsion of transplanted adult worms from mice.

The technique of implanting adult Trichinella spiralis into the intestines of mice has been used to assess the contributions of direct, anti-worm immunity and of intestinal inflammation to worm expulsion. The survival after transfer of worms exposed to an effective adoptive immunity in donors was no different from that of worms taken from control donors. Worms taken from donors 8 days after infection, i.e., shortly before the onset of expulsion, showed no increased susceptibility to an immunity adoptively transferred to the recipient mice. When worms were implanted into mice responding to a prior, oral infection they were expelled rapidly. This expulsion was independent of the age of the worms transferred and took place at the same time as the expulsion of the existing infection.     

Quantifying Phenotypic Variation in Isogenic Caenorhabditis elegans Expressing Phsp-16.2::gfp by Clustering 2D Expression Patterns

Isogenic populations of animals still show a surprisingly large amount of phenotypic variation between individuals. Using a GFP reporter that has been shown to predict longevity and resistance to stress in isogenic populations of the nematode Caenorhabditis elegans, we examined residual variation in expression of this GFP reporter. We found that when we separated the populations into brightest 3% and dimmest 3% we also saw variation in relative expression patterns that distinguished the bright and dim worms. Using a novel image processing method which is capable of directly analyzing worm images, we found that bright worms (after normalization to remove variation between bright and dim worms) had expression patterns that correlated with other bright worms but that dim worms fell into two distinct expression patterns. We have analysed a small set of worms with confocal microscopy to validate these findings, and found that the activity loci in these clusters are caused by extremely bright intestine cells. We also found that the vast majority of the fluorescent signal for all worms came from intestinal cells as well, which may indicate that the activity of intestinal cells is responsible for the observed patterns. Phenotypic variation in C. elegans is still not well understood but our proposed novel method to analyze complex expression patterns offers a way to enable a better understanding.