Showing papers in "Journal of Helminthology in 1989"
TL;DR: It is concluded that the cysticerci of goat and pig origin probably represent two different strains and possibly follow the same pattern of speciation as reported in the related taeniid, Echinococcus granulosus.
Abstract: Analysis of the major biochemical components of Taenia hydatigena cysticerci collected from goats and pigs showed marked differences, particularly in glycogen, protein, lipid and DNA levels. Differences were also detected in the levels of cholesterol, triglycerides, free fatty acids and phospholipids. Furthermore, the profile of phospholipid fractions revealed quantitative differences between the two species. It is concluded that the cysticerci of goat and pig origin probably represent two different strains and possibly follow the same pattern of speciation as reported in the related taeniid, Echinococcus granulosus.
38 citations
TL;DR: The unfenced buffalo abattoir and the large number of dogs allowed access to the abattir coupled to the number of buffalo slaughtered in comparison to the other potential hosts, indicates that the buffalo is the most significant host for maintaining the life-cycle of the parasite in this area of India.
Abstract: The present study investigated the suitability and importance of buffaloes, camels, sheep, goats and pigs in maintaining the life-cycle of Echinococcus granulosus in Aligarh, India. A total of 565 (36%) of 1556 buffaloes, 20 (2%) of 1208 goats, 5 (1%) of 559 pigs, 6 (6%) of 109 sheep and two of three camels were found to harbour hydatid cysts. The frequency distribution of the hydatid cysts in each intermediate host species was over-dispersed and in buffaloes cyst fertility increased with increasing cyst size. Of 2171, 95 and four buffalo, goat, and camel cysts examined 327 (15%), two (2%) and three cysts respectively were fertile. No pig or sheep cysts were found to contain protoscoleces. The unfenced buffalo abattoir and the large number of dogs allowed access to the abattoir coupled to the number of buffaloes slaughtered in comparison to the other potential hosts, indicates that the buffalo is the most significant host for maintaining the life-cycle of the parasite in this area of India. Applicable control measures for the region are suggested.
35 citations
TL;DR: The pattern of transmission of human schistosomiasis was studied in Amagunze Village, eastern Nigeria, during 1986-1987 and its high endemicity in the area were thus demonstrated.
Abstract: The pattern of transmission of human schistosomiasis was studied in Amagunze Village, eastern Nigeria, during 1986–1987. The prevalence of Schistosoma haematobium in 119 schoolboys aged 5–12 years was 79%. The geometric mean of intensity of infection was 49 eggs/10 ml urine and the frequency of visible haematuria was 25·2%. No S. mansoni infections were demonstrated. A marked seasonality in population density of Bulinus truncatus, B. forskalii and Biomphalaria pfeifferi was demonstrated with reduced densities during the late rainy and early dry seasons. Schistosoma sp. infected B. truncatus were found in the late dry and early rainy seasons in 2 out of 7 major human water contact sites studied. Seasonality and focality of transmission of S. haematobium and its high endemicity in the area were thus demonstrated.
32 citations
TL;DR: The number of infective O. ostertagi larvae in inoculated cow pats was reduced and herbage larval infectivity around them by 50-71% as compared with the corresponding parameters in control pats and surrounding herbage, reflected in lower egg counts, lower serum pepsinogen levels and higher body weight.
Abstract: Artificially prepared cow pats containing Ostertagia ostertagi eggs were deposited on two comparable grazing plots at weekly intervals during June and July 1987. Before deposition the cow pats, on the one plot, were inoculated with 0·250 g mycelial fragments per kg of faeces of the predacious fungus Arthrobotrys oligospora . On the other control plot comparable numbers of non-inoculated cow pats were placed at the same time. Subsequently, in July, two equal groups of calves were turned out one on each plot to graze for two months after which they were necropsied. The number of infective O. ostertagi larvae in inoculated cow pats was reduced by 42% and herbage larval infectivity around them by 50–71% as compared with the corresponding parameters in control pats and surrounding herbage. After a grazing period of two months the calves on the plot with inoculated cow pats had acquired worm burdens that were on average 37% lower than those of calves on the control plot. The lower degree of parasitism in these calves was also reflected in lower egg counts, lower serum pepsinogen levels and higher body weight.
32 citations
TL;DR: It was concluded that the two agents (A. suum larvae and E. coli) worked together synergistically and bacteria were carried to the lungs by the migrating Ascaris larvae.
Abstract: The effect of intestinal flora on the establishment, development and pathogenicity of Ascaris suum larvae in piglets (Large White breed) was investigated. The infected piglets with Ascaris and Escherichia coli showed signs of pneumonia, cough with respiratory difficulties initially even though these moderated with time. They lost appetite and showed signs of unthriftiness with loss of weight. The packed cell volume was normal but the differential leucocyte counts of the pigs infected with Ascaris larvae and bacteria had high neutrophils, unlike the very high lymphocyte count observed in piglets with ascarids only. The piglets had generalized serous atrophy of body fat. The pericardial and perirenal fats were gelatinous. There was a firm and nodular grey and red hepatization with abscess pockets in the intermediate and anterior one third of the diaphragmatic lobes of the lungs. The liver contained greyish-white and depressed focus immediately dorsal to the area of attachment to the gall bladder with multifocal areas. There was no significant gross lesion in the control animals. Cultural and microscopic examinations of some internal organs of the infected animals showed that bacteria were carried to the lungs by the migrating Ascaris larvae. The combined synergistic effect of Ascaris larvae and E. coli was also investigated and it was concluded that the two agents (A. suum larvae and E. coli) worked together synergistically.
30 citations
TL;DR: Infective larvae of Onchocerca lienalis and O. volvulus implanted subcutaneously within micropore chambers into laboratory hosts moulted to the fourth stage (L4) and underwent limited development and growth.
Abstract: Infective larvae of Onchocerca lienalis and O.volvulus implanted subcutaneously within micropore chambers into laboratory hosts moulted to the fourth stage (L4) and underwent limited development and growth. Similar recoveries of O. lienalis L4 larvae in the range of 33–66% were obtained from chambers implanted into CBA and BALB/c strains of mice, jirds, and the natural bovine host. A relatively constant proportion of larvae survived up to 24 days post implantation and thereafter recoveries declined, although some worms were still alive after 96 days. Recoveries of O. volvulus L4 larvae from chambers given to normal or T-cell deprived mice were equivalent to one another and to those obtained with O. lienalis . Moulting of O. lienalis in chambers was observed on days 3 and 5, in close accordance with the timing of the third moult in cattle following systemic infection. Moulting of O. volvulus occurred between days 3–6. Morphological changes in developing larvae included a small but significant increase in length, a transient increase in width, and early development of the spicular primordia and genital tube. L4 larvae of O. lienalis , but not those of O. volvulus , exhibited 3 distinct caudal papillae not present on infective larvae.
29 citations
TL;DR: The immune response of hamsters to a chronic hookworm infection has been investigated and cells from both the mesenteric lymph node and spleen, after an initial period of increased blast cell activity, became less reactive in the latter stages of infection.
Abstract: The immune response of hamsters to a chronic hookworm infection has been investigated. Ancylostoma ceylanicum caused long term infections in hamsters which were associated with prominent changes in secondary lymphoid organs. The mesenteric lymph nodes and spleens increased rapidly in size stabilizing at approximately 3-4 times the weight in control animals by weeks 3-7. Cells from both the mesenteric lymph node and spleen, after an initial period of increased blast cell activity, became less reactive in the latter stages of infection. Serum antibody responses were marked, commencing in weeks 3-4 and increasing in intensity throughout the 10 week period of measurement. The results are discussed in relation to their contribution to the understanding of human hookworm infection.
27 citations
TL;DR: The results suggest that these free fatty acids cause physiological changes that determine the developmental course of L1 of S. ratti in nature.
Abstract: The effect of fatty acids was studied on the developmental direction of Strongyloides ratti first-stage larvae (L1). The proportion of third-stage infective larvae increased markedly when L1 were cultured in faeces with added fatty acids such as palmitic (C16), stearic (C18), oleic (C18:1) and linoleic (C18:2) acids. Unsaturated fatty acids were more effective than saturated ones. Moreover, the proportion of infective larvae increased with quantity of linoleic acid but the triacylglycerols of any fatty acid had no effect. These results suggest that these free fatty acids cause physiological changes that determine the developmental course of L1 of S. ratti in nature.
24 citations
TL;DR: A significant reduction was shown in worm length from mice compared to that from cotton rats, and marked differences in mortality and in worm burden were found among inbred strains of mice tested.
Abstract: Experimental Angiostrongylus costaricensis infection was carried out in inbred strains of mice (C57BL/6 BALB/c, DBA/2 and C3H/He). All strains became infected with this parasite. Marked differences in mortality and in worm burden were found among inbred strains of mice tested. A significant reduction was shown in worm length from mice compared to that from cotton rats.
24 citations
TL;DR: The structure of the male reproductive system of Schistosoma margrebowiei as viewed by light, scanning and transmission electron microscopy is described and suggests that these cells have a secretory function.
Abstract: The structure of the male reproductive system of Schistosoma margrebowiei as viewed by light, scanning and transmission electron microscopy is described. The cirrus tube opens at the genital pore without the presence of a cirrus and is spongy and leaf-like. The structure of the germinal and non-germinal cells of the testes are described. The spermatozoon consists of a head, without an acrosome, and a flagellum with a 9 + 0 arrangement of microtubules in the axial filament. A large mass of mitochondria is situated in the anterior end of the head and cortically arranged longitudinally running microtubules are present. The apical region of the epithelial cells of the vas deferens extends into the lumen of the duct forming convoluted lamellae. This arrangement, together with the presence of dense bodies within the cells, suggests that these cells have a secretory function.
21 citations
TL;DR: A canine zoographic study was conducted, and fresh faecal deposits were collected and analysed for helminth life-cycle stages, finding a high level of multiple infection in the host animals.
Abstract: This study investigates the level of helminthic infestation in better-cared-for dogs in a middle-class community in suburban Kingston. A canine zoographic study was conducted, and fresh faecal deposits were collected and analysed for helminth life-cycle stages. The survey indicated that 73% (n = 93) of households in the study area owned one dog or more (mean = 1.4). Resident's attitudes towards canine management suggested that the dog population was, in general, restricted to the residential estate, and most owners claimed to have dewormed their dogs at least as young animals. Of 141 faecal specimens, 58% contained eggs or larvae of one or more of eight helminths: Uncinaria stenocephala (26%), Ancylostoma sp. (23%), Trichuris vulpis (9%), Toxocara canis (8%), Spirocerca lupi (6%), Strongyloides sp. (6%), Apophallus sp. (4%) and taeniids (1%). There was a high level of multiple infection in the host animals, with approximately one fifth of the infected samples containing three or more helminth types. Infection intensity was apparently low, but some dogs harboured heavy worm loads.
TL;DR: Kinetic analysis of the incorporation of labelled substrate, sodium-1-14C acetate, reveals that gangliosides are the fastest biosynthesizing and turning over lipids, although they constitute only 0.1% of the total lipids.
Abstract: Adult males and females of Trichuris globulosa, an intestinal nematode parasite of goats, were studied for their lipid composition, capability of incorporation of (Na)-1-14C-acetate into different lipid classes and the activity of certain key enzymes of lipid metabolism. The parasite possesses a large variety of lipids including certain complex lipids. These are phosphatidylcholine (PC), diphosphatidylglycerol (cardiolipin), lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), phosphatidylserine (PS), phosphatidylinositol (PI), plasmalogens (choline + ethanolamine), mono-, di- and triacylglycerols, free and esterified cholesterol, non-esterified fatty acids (NEFA), gangliosides, cerebrosides (glycosyl ceramide) and sulphuric acid esters of cerebrosides (sulphatides). The females contain more lipids than males, particularly the acylglycerols and phospholipids, possibly to meet the energy requirement and structural entities for the daily production of large numbers of eggs. Incorporation studies of labelled substrate, sodium-1-14C acetate demonstrate that the adult female has extremely active mechanisms for biosynthesizing these lipids. Most of the labels are found in PC, PE, SM, acylglycerols, NEFA, gangliosides, cerebrosides and sulphatides. Cholesterol, although a minor component of the parasitic lipids, incorporates large amount of label and also undergoes fast turnover. Kinetic analysis of the incorporation by measuring the rate constant (k) and half life (t1/2) reveals that gangliosides are the fastest biosynthesizing and turning over lipids, although they constitute only 0.1% of the total lipids. The presence of important enzymes of lipid biosynthesis, glucose-6-phosphate dehydrogenase, malate dehydrogenase and hydroxymethyl glutaryl-CoA reductase and an enzyme of lipid ester hydrolysis, triacylglycerol lipase, is also established in T. globulosa. Michaelis-Menten kinetic characteristics of the parasitic enzymes (Km, Vmax, v and the first order rate constant, k) are comparable with those of rat liver homogenates.
TL;DR: Peritoneal Echinococcus granulosus in gerbils was treated with albendazole and the ability of the parasite to recover after treatment was found to depend on dose and length of therapy.
Abstract: Peritoneal Echinococcus granulosus in gerbils was treated with albendazole. Both early and late infections were studied; response to albendazole therapy and the ability of the parasite to recover after treatment was found to depend on dose and length of therapy. Even after treatment at 50 mg/kg for 2 months late infections retained the ability to recover over 3 months.
TL;DR: Faecal pads were the sole reservoir of L3 during the dry season and hence the source of the early rains herbage infestation, according to the overall trend of faecal larval populations in each paddock, which is distinctly curvilinear.
Abstract: Five experimental grass paddocks were sequentially contaminated with fresh bovine faeces containing known numbers of eggs of predominantly Haemonchus and Cooperia spp. during the 1984/85 dry season (November to March). Faecal, herbage and soil samples were examined at regular intervals between November and June in order to determine the rate of development and mortality of infective larvae (L3) in faeces, the pattern of herbage infestation with L3 and the role of faeces and soil as reservoirs of L3 during the dry season and early rains. L3 first appeared in faeces approximately 4 days post contamination (PC) and peak counts were obtained 28, 14, 7 and 14 days PC in the paddocks contaminated in December, January, February and March, respectively. The counts initially declined linearly at the rate of approximately 7535 L3/week and 10,947 L3/week in P2 and P4 respectively, due primarily to mortality but later there was an accelerated fall in the counts as the surviving L3 moved out of the faecal pads onto herbage. The overall trend of faecal larval populations in each paddock was therefore distinctly curvilinear. Although large numbers of L3 were present inside dry faecal pads in most paddocks throughout the dry season, none migrated on to herbage at that time of the year. Translation of L3 to herbage was very rapid and occurred simultaneously in all the paddocks 24 hours following the first heavy rainfall in late March. Consequently peak herbage infestations in all paddocks were coincident and occurred a few days after commencement of larval migration. The closer to the end of the dry season the contaminations were carried out, the larger were the subsequent early rains rise and the peak herbage infestation and the longer this infestation survived on herbage. No L3 were recovered from soil throughout the study, which suggests that faecal pads were the sole reservoir of L3 during the dry season and hence the source of the early rains herbage infestation.
TL;DR: It is shown that growing flukes (smaller forms) with active oogenesis and spermatogenesis contained more zinc than old (large) or very old adults with an empty uterus and large lobulated testes and fully grown cyst walls.
Abstract: The distribution of zinc in representative groups of parasitic helminths was determined by the use of the atomic absorption spectrophotometer. The results of these analyses have shown that growing flukes (smaller forms) with active oogenesis and spermatogenesis contained more zinc than old (large) or very old adults with an empty uterus and large lobulated testes. In cestodes, the neck region and immature proglottids showed more zinc concentration than mature and gravid proglottids and fully grown cyst walls. Similarly, the youngest endogenous daughter cysts of Echinococcus granulosus contained more zinc in their walls than those of larger/older forms. Zinc was concentrated more in nematode eggs than in adult females.
TL;DR: Hydatid fluid collected from the lungs and livers of sheep and humans was analysed for protein and lipid composition and the major lipids were triglycerides and diglycerides.
Abstract: Hydatid fluid collected from the lungs and livers of sheep and humans was analysed for protein and lipid composition. There were no marked differences in the composition of these parameters and the major lipids were triglycerides and diglycerides. The phospholipids, which formed the minor fraction, were mainly phosphatidyl choline and phosphatidyl inositol. Cholesterol present was in the free form.
TL;DR: A case is presented of infection by Oesophagostomum, a nematode worm, producing a cutaneous nodule in man, believed to be the first in which the worm has produced a lesion outside the gastro-intestinal tract and without evidence of bowel infection.
Abstract: A case is presented of infection by Oesophagostomum, a nematode worm, producing a cutaneous nodule in man. Of the 70 individual cases reported in man it is believed that this is the first in which the worm has produced a lesion outside the gastro-intestinal tract and without evidence of bowel infection. This finding suggests either that the worm is able to achieve direct skin penetration or that it can be disseminated from the bowel via the bloodstream or the lymphatics. The pathology caused by Oesophagostomum and the possible modes of infection are discussed in relation to studies in animals, particularly simians and cattle.
TL;DR: The technique of allozyme electrophoresis was applied to species of Onchocerca from cattle to increase the number of enzyme loci established and therefore provide a genetic basis for a rational species-level taxonomy and form the basis for identification of life-cycle stages, individuals and species and population structure analyses.
Abstract: The technique of allozyme electrophoresis was applied to species of Onchocerca from cattle to increase the number of enzyme loci established and therefore provide a genetic basis for a rational species-level taxonomy. Twenty-three enzyme loci were established and provided unequivocal genetic evidence for the taxonomic validity of Onchocerca gibsoni, O. gutturosa and O. lienalis. Furthermore, the diagnostic enzyme markers detected form the basis for identification of life-cycle stages, individuals and species and population structure analyses.
TL;DR: In this article, the prevalence and relative density of Paradiplozoon homoion were monitored over one year in populations of roach Rutilus rutilus, captured in a thermally raised artificial lake located outside a nuclear power station and in a nearby reference locality.
Abstract: The prevalence and relative density of the monogenean Paradiplozoon homoion, were monitored over one year in populations of roach, Rutilus rutilus, captured in a thermally raised artificial lake located outside a nuclear power station and in a nearby reference locality. Recruitment of P. homoion started earlier in the warmer lake. A temporal shift of the life-cycle was thus observed but there were no differences between the total prevalence or the total relative density of the parasite in the two areas. Since there is no evidence of parasite-induced host mortality, or for the development of protective immunity, the main regulatory process in the heated area are most likely an increased mortality due to reduced thermal tolerance of the adult parasite.
TL;DR: No significant difference in cercarial production was noted when Biomphalaria glabrata from Brazil were exposed to one or several miracidia of Schistosoma rodhaini from Burundi, even though the dynamics seemed different.
Abstract: No significant difference in cercarial production was noted when Biomphalaria glabrata from Brazil were exposed to one or several miracidia of Schistosoma rodhaini from Burundi, even though the dynamics seemed different. The minor differences can be explained by the intramolluscal larval development of this parasite characterized by the production of a high number of daughter sporocysts over a long period.
TL;DR: The infected ileum showed atrophic villi, hypertrophied circular musculature with collagen-like fibres and haemorrhagic zones, and Worms in contact with host mucosa showed tissue plugs in the suckers.
Abstract: Domestic chicks experimentally infected with Echinostoma caproni for 2 weeks showed a dilated ileum, unkempt feathers, watery diarrhoea, and weight loss. The ileum from infected and control chicks was fixed in 10% neutral buffered formalin, and prepared as 10 microns paraffin sections stained in haematoxylin and eosin, Papanicolau, periodic acid-Schiff, picro-ponceau, and alcian blue. The infected ileum showed atrophic villi, hypertrophied circular musculature with collagen-like fibres and haemorrhagic zones. The brush borders of epithelial cells and goblet cells were absent in the mucosa of the infected ileum. Worms in contact with host mucosa showed tissue plugs in the suckers. The cephalic spines of worms abraded the host mucosa.
TL;DR: It is suggested that macrophages have more important role(s) than do eosinophils on the expression of sex difference in the susceptibility to a primary B. pahangi infection in C57BL/6 mice.
Abstract: The role of macrophages or eosinophils on the expression of sex difference in the susceptibility to a primary Brugia pahangi infection in C57BL/6 mice was investigated by using a macrophage blockade technique (carbon treatment) or a histamine type 1 (H1) receptor antagonist (promethazine). Carbon treatment remarkably inhibited macrophage exudation, reduced the resistance of female mice, and completely abolished sex difference in the susceptibility to B. pahangi infection. Although promethazine treatment inhibited eosinophil exudation, it caused only a little increase (not significant) in the recovery rate of worms. These results suggest that macrophages have more important role(s) than do eosinophils on the expression of sex difference in the susceptibility to a primary B. pahangi infection in C57BL/6 mice.
TL;DR: Third larval stages (L3) removed from fish fillets, fourth larval Stage (L4) raised in in vitro culture, and adults of Pseudoterranova decipiens, collected from grey seal stomachs, were exposed to the broad spectrum anthelmintic, ivermectin.
Abstract: Third larval stages (L3) removed from fish fillets, fourth larval stages (L4) raised in in vitro culture, and adults of Pseudoterranova decipiens, collected from grey seal (Halichoerus grypus) stomachs, were exposed to the broad spectrum anthelmintic, ivermectin. L3 and L4 parasites were exposed, in vitro, to 500, 100, 50, 20, 5 and 1 μg/ml concentrations of the drug, in culture media. Adult P. decipiens were exposed in vitro to a concentration of 500 μg/ml ivermectin, only. Controls consisted of parasites placed in culture media alone or culture media plus drug vehicle. These three developmental stages of P. decipiens were all found to be susceptible to the effects of ivermectin.
TL;DR: It was concluded that CIEP can be used as a field test for the anti-mortem diagnosis and ELISA can be employed for laboratory confirmation of T. solium cysticercosis in pigs using fractionated 1st peak antigen.
Abstract: The sensitivity and specificity of double immunodiffusion (DID), indirect haemagglutination test (IHA), immunoelectrophoresis (IEP), counterimmunoelectrophoresis (CIEP) and enzyme-linked immunosorbent assay (ELISA) were evaluated and compared using saline extracted of Taenia solium larval scolex and its Sephadex G-200 fractionated 1st and 2nd peak as antigens. Various immunodiagnostic tests gave different results with different antigens. Highest sensitivity (92·5%) was obtained with ELISA using 1st peak antigen and lowest sensitivity was obtained with DID. However, 88·4% and 84·6% sensitivity was obtained with IHA and CIEP respectively using scolex antigen. CIEP gave better results as compared to IEP. Crude antigen gave high sensitivity but less specificity. It was concluded that CIEP can be used as a field test for the anti-mortem diagnosis and ELISA can be employed for laboratory confirmation of T. solium cysticercosis in pigs using frationated 1st peak antigen.
TL;DR: During the intramolluscan larval development of Schistosoma haematobium (Algerian strain) in Bulinus truncatus, two replication processes of daughter sporocysts occur that assure a periodic renewal of the sporocyst stock in the snail host and seem to be synchronized with the development of cercarial generations.
Abstract: During the intramolluscan larval development of Schistosoma haematobium (Algerian strain) in Bulinus truncatus, two replication processes of daughter sporocysts occur. Replication by direct sporocystogenesis appears more important than sporocystogenesis post cercariogenesis. These mechanisms assure a periodic renewal of the sporocyst stock in the snail host and seem to be synchronized with the development of cercarial generations. The succession of several generations of cercariae is responsible for the alternation of high and low periods of productivity. The scheme proposed for the intramolluscan development of S. haemtobium is compared with those described for S. mansoni and S. bovis and interpreted in terms of demographic strategies adapted to a better exploitation of the snail host.
TL;DR: The results suggest that the RFLPs analysis may be useful for distinguishing Anisakinae larvae and clarifying the relationships between Anisakis larvae and their adult worms.
Abstract: The analysis of restriction fragment length polymorphisms (RFLPs) was applied to distinguish several kinds of Anisakinae larvae, Anisakis larvae (type I) collected from two different paratenic hosts, Anisakis larvae (type II) and Contracaecum larvae. The patterns of the two different paratenic host-derived DNA of Anisakis larva (I) were exactly the same in hybridized fragments generated by six endonucleases. The quite different patterns in RFLPs of genomic DNA were observed among the Anisakis larva (I), Anisakis larva (II) and Contracaecum larvae. The results suggest that the RFLPs analysis may be useful for distinguishing Anisakinae larvae and clarifying the relationships between Anisakis larvae and their adult worms.
TL;DR: A variety of other pretreatments and treatments were tested but pepsin appears to be the most effective “primer”, apparently producing localized changes which permit the exit of the metacercaria.
Abstract: It has been established that the wall of the metacercarial cyst of the strigeid digenean Apatemon (Australapatemon) minor from the leech Erpobdella octoculata shares with Apatemon (Apatemon) gracilis the remarkable ability to expel the metacercaria forcibly from the cyst, an event which presumably occurs when the cysts are eaten by the bird definitive host. When cysts of A. minor are treated in vitro with a solution containing a mixture of bile salts and trypsin following pretreatment with acid pepsin, the metacercaria is expelled in an explosive manner through a canal at the narrow end of the pear-shaped cyst. This expulsion is produced by a sudden and substantial inward expansion of the birefringent wall, as a consequence of which the cyst lumen is virtually eliminated. Expulsion of the metacercaria in this explosive manner also occurs when similarly pretreated cysts are exposed to either bile salts alone or to trypsin, but cysts treated with the latter take longer to respond. When the cyst wall is perforated with a needle, inward expansion of the wall occurs and the metacercaria is forcibly ejected through the perforation. A variety of other pretreatments and treatments was tested but pepsin appears to be the most effective “primer”, apparently producing localized changes which permit the exit of the metacercaria. These observations are discussed in relation to the mechanism of expulsion.
TL;DR: Observations made on cercariae during penetration indicate that the paraoesophageal glands are used to enter the body of the planarian and that the so-called penetration glands have some other function.
Abstract: An echinostome cercaria (? Cercaria spinifera La Valette, 1855) with 37 collar spines and paraoesophageal glands has been recorded for the first time in Britain from the gastropod Planorbarius corneus. The cercariae penetrate into and encyst in planarians. Observations made on cercariae during penetration indicate that the paraoesophageal glands are used to enter the body of the planarian and that the so-called penetration glands have some other function. Gastropod molluscs may also serve as second intermediate hosts, but there is evidence to indicate that anatomically similar cercariae from different host individuals vary in their second intermediate host preferences
TL;DR: The facts show the existence of immunological differences among proteins with apparently identical molecular weights in T. spiralis and T. pseudospiralis infective larvae, using a monoclonal antibody named ES/TA2.
Abstract: Crude saline extracts of Trichinella spiralis and T. pseudospiralis infective larvae were studied by Western blot analysis using a monoclonal antibody, named ES/TA2 and produced against T. spiralis larvae. This monoclonal antibody recognized seven major antigenic components in T. spiralis larvae with apparent Mr: 45, 48, 50, 68, 70, 92 and 105 kDa and five in T. pseudospiralis larvae: 38, 50, 70, 72 and 92 kDa. SDS-PAGE of both extracts did not reveal appreciable differences in the range of molecular weights recognized by ES/TA2. These facts show the existence of immunological differences among proteins with apparently identical molecular weights.