Search

Purpose: Ascariasis caused by the helminth Ascaris suum is the most common parasitosis of swine worldwide and it may involve all age categories of pigs. The present study reports an unusual localization of A.suum worms in the biliary system of a piglet slaughtered for human consumption. Methods: The liver was subjected to ultrasound scan and pathological examination. The isolated worms were morphologically examined and the DNA was extracted for the molecular identification of the species involved. Results: A total of 43 preadult nematodes were found within the gallbladder and the bile ducts. Parasites were morphologically identified as belonging to the genus Ascaris and molecularly as A. suum. At gross examination, the liver was moderately enlarged, with the bile ducts severely dilated. A chronic inflammatory infiltrate was noted, often centered around ectatic bile ducts (up to 5 mm in diameter), lined by hyperplastic epithelium and filled with sections of nematodes. The worm sections showed smooth cuticle, coelomyarian musculature, and an intestinal tract lined by columnar, uninucleated cells within a pseudocoelom. The ex vivo ultrasonographic examination of the liver allowed the visualization of several nematodes in the bile duct lumen and could be suggested for in vivo diagnosis. Unfortunately, the absence of the intestine did not allow to define the pathogenesis of the infection. Conclusion: Although, given the unusual nature of this finding, it is difficult to identify predisposing factors for this A. suum localization, it suggests that ascariasis should be considered in the differential diagnosis of pigs with hepatobiliary disease. [ABSTRACT FROM AUTHOR]

The nematode parasite intestine absorbs nutrients, is involved in innate immunity, can metabolize xenobiotics and as we show here, is also a site of action of the anthelmintic, diethylcarbamazine. Diethylcarbamazine (DEC) is used to treat lymphatic filariasis and activates TRP-2, GON-2 & CED-11 TRP channels in Brugia malayi muscle cells producing spastic paralysis. DEC also has stimulatory effects on ascarid nematode parasites. Using PCR techniques, we detected, in Ascaris suum intestine, message for: Asu-trp-2, Asu-gon-2, Asu-ced-11, Asu-ocr-1, Asu-osm-9 and Asu-trpa-1. Comparison of amino-acid sequences of the TRP channels of B. malayi, and A. suum revealed noteworthy similarity, suggesting that the intestine of Ascaris will also be sensitive to DEC. We used Fluo-3AM as a Ca2+ indicator and observed characteristic unsteady time-dependent increases in the Ca2+ signal in the intestine in response to DEC. Application of La3+ and the TRP channel inhibitors, 2-APB or SKF 96365, inhibited DEC mediated increases in intracellular Ca2+. These observations are important because they emphasize that the nematode intestine, in addition to muscle, is a site of action of DEC as well as other anthelmintics. DEC may also enhance the Ca2+ toxicity effects of other anthelmintics acting on the intestine or, increase the effects of other anthelmintics that are metabolized and excreted by the nematode intestine. [ABSTRACT FROM AUTHOR]

Ascaris lumbricoides and Ascaris suum are described as helminths that infect humans and pigs, respectively. It is estimated that infection by A. lumbricoides affects about 447 million individuals living in tropical regions of developing countries. However, there is an increasing number of cases of human ascariasis in countries with no recent history of autochthonous infection by A. lumbricoides. In these places, pigs have been incriminated as the main source of human infection. Conventional parasitological diagnosis does not allow species-specific identification, and the real epidemiological scenario of human and swine ascariasis is still uncertain. Therefore, this work presents the application of a species-specific molecular diagnosis, based on the allele-specific PCR methodology (AS-PCR), using the Internal Transcript Space 1 (ITS-1) of the ribosomal DNA, as a target for differentiating between the two species, using DNA obtained from eggs. To validate the methodology, stool samples positive for Ascaris spp, were obtained from 68 humans from seven Brazilian states and from six pigs from the state of Minas Gerais. All samples obtained from humans were genotyped as A. lumbricoides and all samples obtained from swine were genotyped as A. suum. These results are in agreement with the literature, which demonstrates that in most endemic regions, transmission cycles are separate. Therefore, the execution of this work allowed the availability of a useful methodology for the differential diagnosis of the species, which may contribute to the characterization of the real epidemiological profile of human and swine ascariasis, and to the implementation of future control strategies. [ABSTRACT FROM AUTHOR]

Purpose: Breeding of wild boars is a significant part of the hunting economy; however, hogs are associated with zoonotic infection. This study assessed the prevalence and degree of parasitic infections that exist in wild boars from two hunting grounds in the Autonomous Province of Vojvodina, Republic of Serbia. Methods: Parasitological examinations were conducted from 2016 to 2019. In total 220 fecal samples and 13 lungs were collected from wild boars in two hunting grounds (an open and a closed habitat) on the territory of Vojvodina (Serbia). Assessment of the prevalence and degree of the detected endoparasitosis involved a semi-quantitative fecal egg count method. Results: The presence of protozoa—Eimeria spp./Isospora spp. (76.38%; 32.26%) and Balantidium coli (7.08%), nematodes—Ascaris suum (29.03%), Trichuris suis (31.49%; 19.35%), Hyostrongylus rubidus/Oesophagostomum spp. (55.12%; 48.39%), Metastrongylus pudendotectus (66.14%; 21.51%), Gnathostoma hispidum (3.94%; 2.15%) and Macracanthorhynchus hirudinaceus (9.45%; 7.53%) and trematodes—Fasciola hepatica (5.51%; 4.30%) and Dicrocoelium dendriticum (0.78%; 2.30%) were detected as single or mixed infections, via qualitative coprological examination. The total prevalence of the endoparasitosis was 92.91% in hunting ground I (closed habitat) and 73.12% in hunting ground II (open habitat). The most prevalent infection in hunting ground I was coccidiosis (76.38%), and hyostrongylosis/oesophagostomosis (48.39%) in hunting ground II. Adult forms of M. pudendotectus were identified in the lungs of 13 wild hogs with mild to severe bronchopneumonia from hunting ground II. Conclusions: The semi-quantitative fecal egg count method demonstrated clinical and parasitological significance and revealed the risks associated with zoonotic infections in this game species population. Therefore, monitoring the etiology and epizootiology of parasitic infections in wild boars is essential for creating health care programs in hunting ground areas and planning control strategies that protect both the hunting economy and public health. [ABSTRACT FROM AUTHOR]

To ensure that meat from livestock and game is safe for human consumption, European legislation lays down rules for mandatory testing. Helminth larvae are a category of zoonotic foodborne pathogens that can contaminate meat. Among helminths, the only zoonotic nematode regulated in Europe regarding meat inspection is Trichinella spp.. It is precisely during Trichinella testing that other potentially zoonotic larvae can be found. Due to current lack of tools, their identification is often very complicated. Nematode larvae other than Trichinella, recovered from artificial digestions of pig and wild boar muscles from France and Germany, were subjected to a newly developed two-step identification scheme, which includes both morphological examination and molecular assays. The first step is a general orientation towards a broad taxonomic group; the second step consists of targeted identification based on the results of first step. Different parasites were identified, some of which were not zoonotic such as Metastrongylus spp. and Angiostrongylus vasorum, but others are known to be zoonotic such as Toxocara cati, Ascaris suum, and Uncinaria stenocephala. The strategy is efficient for the identification of nematode larvae recovered from muscles but could also be applied for larvae from other sources. [ABSTRACT FROM AUTHOR]

The EU regulation for organic pig production requires outdoor access to promote the animal welfare. This may increase the risk of infection of the common pig parasites, Ascaris suum and Trichuris suis, because their eggs can survive for many years in the soil. The egg contamination of these parasites in outdoor areas with different managements and the faecal egg output from the pigs was investigated on 11 Swedish organic pig farms in 2008. We found eggs of A. suum and, to a minor extent, T. suis in the soil from outdoor areas, which had previously been used for pig rearing and/or for spreading of pig manure. Piglets and their dams were turned out on pastures included in a crop rotation, and these areas had a mean of 2500 A. suum and 40 T. suis eggs per kilogram soil. When the pigs were 12-week-old, the faecal egg counts (FECs) of A. suum were positively correlated with the egg concentration in pasture soils before pig turnout. The areas used by dry sows had a mean of 11,700 A. suum and 220 T. suis eggs per kilogram soil. The highest egg concentrations in the soil were found in areas, frequently used by pigs in the most recent years. To minimise pasture contamination with parasite eggs, it is advised to have a crop rotation system and to inactivate parasite eggs in pig manure before spreading it. Parasite control needs further development to protect suckling piglets from infections due to environmental parasite egg contamination. [ABSTRACT FROM AUTHOR]

Schistosoma japonicum and Ascaris suum are considered as the major parasites of human which cause various life threatening diseases such as schistomiasis and ascariasis. The codon usage bias (CUB) is known as the phenomenon of more usage of a specific codon than the other synonymous codons for an amino acid. The factors that influence the codon usage bias are mutation pressure, natural selection, gene expression, gene length, GC content, RNA stability, recombination rates, codon position etc. Here we had used various bioinformatic tools and statistical analyses to understand the compositional features, expression level and codon usage bias in the genes of these two species. After estimating the effective number of codon (ENC) in both the species, codon usage bias was found to be low and gene expression was high. The nucleobase A and T were used most often than C and G. From neutrality plot and correspondence analysis it was found that both natural selection and mutation pressure played an important role in shaping the codon usage pattern of both species. Moreover, natural selection played a major role while mutation pressure played a minor role in shaping the codon usage bias in S. japonicum and A.suum. This is the first report on the codon usage biology in S. japonicum and A.suum, and the factors influencing their codon usage bias. These results are expected to be useful for genetic engineering and evolutionary studies. [ABSTRACT FROM AUTHOR]

A single nucleotide polymorphism on chromosome 4 (SNP TXNIP) has been reported to be associated with roundworm (Ascaris suum) burden in pigs. The objective of the present study was to analyse the immune response to A. suum mounted by pigs with genotype AA (n = 24) and AB (n = 23) at the TXNIP locus. The pigs were repeatedly infected with A. suum from eight weeks of age until necropsy eight weeks later. An uninfected control group (AA; n = 5 and AB; n = 5) was also included. At post mortem, we collected mesenteric lymph nodes and measured the expression of 28 selected immune-related genes. Recordings of worm burdens confirmed our previous results that pigs of the AA genotype were more resistant to infection than AB pigs. We estimated the genotype difference in relative expression levels in infected and uninfected animals. No significant change in expression levels between the two genotypes due to infection was observed for any of the genes, although IL-13 approached significance (P = 0.08; Punadjusted = 0.003). Furthermore, statistical analysis testing for the effect of infection separately in each genotype showed significant up-regulation of IL-13 (P<0.05) and CCL17 (P<0.05) following A. suum infection in the 'resistant' AA genotype and not in the 'susceptible' AB genotype. Pigs of genotype AB had higher expression of the high-affinity IgG receptor (FCGR1A) than AA pigs in both infected and non-infected animals (P = 1.85*10-11). [ABSTRACT FROM AUTHOR]

Ascarid nematodes, Ascaris suum, Toxocara canis and Toxocara cati, are the most important causative species of larva migrans syndrome (LMS) in humans. Although the diagnosis of ascarid LMS is generally based on serological tests, specific serological tests for A. suum infection have not been fully developed. In the present study, the sensitivity and specificity of three A. suum antigen preparations, i.e., the somatic adult worm antigen (As-SWAP), larval excretory-secretory (ES) antigens derived from infective L3 (AsiL3-ES) and larval ES from tissue migratory L3 (AsmL3-ES), were evaluated for the serodiagnosis of A. suum infection in enzyme-linked immunosorbent assay (ELISA). We found that all A. suum antigen preparations showed positive reaction to all sera from A. suum-infected mice, while only AsmL3-ES obtained 100 % detection of anti- A. suum antibodies in human visceral ascarosis patients. Comparing the reactivity of each A. suum antigen, sera from both A. suum-infected mice and human patients bound to AsiL3-ES significantly weaker than As-SWAP and AsmL3-ES. Moreover, the OD values of ELISA with the A. suum antigen preparations and T. canis larval ES antigen (TciL3-ES) were compared in order to discriminate between ascarosis and toxocarosis. Linear discriminant analysis showed that diagnosis based on TciL3-ES and AsmL3-ES ELISA gave the most reliable result for the discrimination of infecting species. In conclusion, the application of AsmL3-ES antigen in ELISA can be recommended for the serodiagnosis of A. suum infection in humans. [ABSTRACT FROM AUTHOR]

Toxocara canis, Toxocara cati and Ascaris suum are worldwide-distributed zoonotic roundworms of dogs, cats and pigs, respectively. The epidemiology of these parasites in developed countries is largely unclear. Two countrywide cross-sectional serosurveys were therefore conducted in the Netherlands in 1995/1996 and 2006/2007 to investigate the prevalence, trends and risk factors for human Toxocara and Ascaris infections in the general population. The Netherlands is characterized by high pig production, freedom from stray dogs and virtual absence of autochthonous infections with the human-adapted roundworm Ascaris lumbricoides. Over the 10 years between the two serosurveys, Toxocara seroprevalence decreased significantly from 10.7 % ( n = 1159) to 8.0 % ( n = 3683), whereas Ascaris seroprevalence increased significantly from 30.4 % ( n = 1159) to 41.6 % ( n = 3675), possibly reflecting concomitant improvements in pet hygiene management and increased exposure to pig manure-contaminated soil. Increased anti- Toxocara IgGs were associated with increasing age, male gender, contact with soil, ownership of cats, cattle or pigs, hay fever, low education, high income and non-Western ethnic origin. Increased anti- Ascaris IgGs were associated with increasing age, owning pigs, low education, childhood geophagia and non-Dutch ethnic origin. Besides identifying specific groups at highest risk of Toxocara and Ascaris infections, our results suggest that these infections mainly occur through environmental, rather than foodborne, routes, with direct contact with soil or cat and pig ownership being potentially modifiable exposures. [ABSTRACT FROM AUTHOR]

The pig roundworm, Ascaris suum, is commonly found in domestic pigs all over the world. The transmission to humans takes place by ingestion of infective A. suum eggs present in soil because pig manure is widely used as fertilizer. The possible role of A. suum in the human visceral larva migrans (VLM) syndrome has been discussed controversially during past decades, even though various case reports, particularly from Japan document pulmonal, hepatic and even cerebral symptoms caused by migrating A. suum larvae after ingestion of infected row meat (liver) or contaminated vegetables. We examined 4481 sera by A. suum immunoblot (As-IB) and 5301 sera by Toxocara-ELISA from patients with symptoms associated with the VLM syndrome during three consecutive years (2012-2014). The incidence of A. suum-specific antibodies was 13.2 %, the incidence of T. canis specific antibodies 12.9 % and from a part of the As-IB positive sera ( n = 417) additional Toxocara serology was performed to demonstrate the specificity of our tests. Only 56 out of the 417 (13.4 %) sera showed antibodies to both helminth species demonstrating that double infections exist. Interestingly the age distribution of the patients showed that 2.8 % of the Ascaris-positive patients were younger than 21 years, while in the Toxocara-positive group 13.4 % were <21 years. These results are in accordance with a Dutch study suspecting different ways of transmission as cause for this interesting age distribution. Due to the fact that large amounts of untreated pig manure are used as fertilizer and that the expulsion of adult A. suum worms causing intestinal ascariosis is extremely rare in Central European countries, the zoonotic potential of A. suum is considerably underestimated. We suggest that the performance of reliable immunoserological tests, in all industrialized countries where pigs are raised and their manure is used as fertilizer, could help to assess the actual potential of A. suum as causative agent of the VLM syndrome in humans. [ABSTRACT FROM AUTHOR]

In multicellular parasites (e.g., nematodes and protozoa), proteins and glycolipids have been found to be decorated with phosphorylcholine (PC). PC can provoke various effects on immune cells leading to an immunomodulation of the host's immune system. This immunomodulation allows long-term persistence but also prevents severe pathology due to downregulation of cellular immune responses. PC-containing antigens have been found to interfere with key proliferative signaling pathways in B and T cells, development of dendritic cells and macrophages, and mast cell degranulation. These effects contribute to the observed modulated cytokine levels and impairment of lymphocyte proliferation. In contrast to glycosphingolipids, little is known about the PC-epitopes of proteins. So far, only a limited number of PC-modified proteins from nematodes have been identified. In this project, PC-substituted proteins and glycolipids in Ascaris suum have been localized by immunohistochemistry in specific tissues of the body wall, intestine, and reproductive tract. Subsequently, we investigated the PCome of A. suum by 2D gel-based proteomics and detection by Western blotting using the PC-specific antibody TEPC-15. By peptide-mass-fingerprint matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), we could identify 59 PC-substituted proteins, which are in involved multiple cellular processes. In addition to membrane proteins like vitellogenin-6, we found proteins with structural (e.g., tubulins) and metabolic (e.g., pyruvate dehydrogenase) functions or which can act in the defense against the host's immune response (e.g., serpins). Initial characterization of the PC-epitopes revealed a predominant linkage of PC to the proteins via N-glycans. Our data form the basis for more detailed investigations of the PC-epitope structures as a prerequisite for comprehensive understanding of the molecular mechanisms of immunomodulation. [ABSTRACT FROM AUTHOR]

Essential plant oils (or their active principles) are safe to use and a potentially attractive alternative to current antiparasitic drugs. In the present study, we tested the effects of carvacrol on the isolated tissues of Ascaris suum and investigated potential interactions with other antiparasitic drugs. We used somatic muscle flaps for contraction assays, as well as for electrophysiological investigations. Carvacrol 300 μM highly significantly inhibited contractions caused by 1, 3, 10, 30, and 100 μM of ACh ( p = 0.0023, p = 0.0002, p = 0.0002, p < 0.0001, and p < 0.0001). The control EC for acetylcholine was 8.87 μM (log EC = 0.95 ± 0.26), while R was 2.53 ± 0.24 g. The EC of acetylcholine in the presence of 300 μM of carvacrol was 27.71 μM (log EC = 1.44 ± 0.28) and the R decreased to 1.63 ± 0.32 g. Furthermore, carvacrol highly significant potentiates inhibitory effect of GABA and piperazine on the contractions induced by ACh. However, carvacrol (100 and 300 μM), did not produce any changes in the membrane potential or conductance of the A. suum muscle cell. While, 300 μM of carvacrol showed a significant inhibitory effect on ACh-induced depolarization response. The mean control depolarization was 13.58 ± 0.66 mV and decreased in presence of carvacrol to 4.50 ± 1.02 mV ( p < 0.0001). Mean control Δg was 0.168 ± 0.017 μS, while in the presence of 300 μM of carvacrol, Δg significantly decreased to 0.060 ± 0.018 ΔS ( p = 0.0017). The inhibitory effect on contractions may be the explanation of the antinematodal potential of carvacrol. Moreover, inhibition of depolarizations caused by ACh and reduction of conductance changes directly points to an interaction with the nAChR in A. suum. [ABSTRACT FROM AUTHOR]

Visceral larva migrans (VLM) syndrome caused by Toxocara canis larvae was first described in the 1950s. The role of other nematode larvae, i.e. the pig roundworm Ascaris suum as a causative agent of visceral larva migrans-associated symptoms like general malaise, cough, liver dysfunction, hypereosinophilia with hepatomegaly and/or pneumonia, was discussed controversially during the last decades. Recent serological screening studies for specific A. suum antibodies carried out in the Netherlands and Sweden yielded remarkable high seroprevalences, while a number of case reports from Japan report pulmonal, hepatic and cerebral symptoms caused by A. suum larvae after ingestion of infected raw meat (liver) or contaminated vegetables. We present here a sensitive and specific larval excretory-secretory (E/S) antigen-based immunoblot (As-IB) for the serodiagnosis of A. suum-infected patients suffering from symptoms associated to the VLM syndrome. In total, 34 sera from patients with hypereosinophilia and other clinical symptoms associated to the VLM syndrome tested negative for Toxocara sp. antibodies but positive in our newly established As-IB, 30 sera from healthy volunteers, 53 sera from patients with clinically and serologically confirmed toxocarosis and other helminthoses as well as 3 sera from patients with intestinal ascariosis due to Ascaris lumbricoides were included in the study. When evaluated with 30 sera from healthy volunteers and 53 sera from patients suffering from different helminthoses, the calculated specificity of our new As-IB is 95 %. Problems hampering the establishment of simple serological screening tests for specific A. suum antibodies, like extensive antigenic similarities between the nematodes Ascaris and Toxocara or the absence of suitable experimental animals, are discussed. We assume that specific serological testing for antibodies of A. suum is very important for the treatment of individual patients on one hand and seroepidemiological investigations will help to clarify routes of transmission on the other hand. Further studies will be necessary to learn more about the extent of A. suum as a causative agent of the VLM syndrome and the role of pigs and their manure as the main source of human Ascaris infections in Austria and other industrialized countries. [ABSTRACT FROM AUTHOR]

Adult worm extract from Ascaris suum (Asc) has immunosuppressive activity and elicits Th2/IL-4/IL-10 response. This study evaluated the prophylactic and therapeutic effect of Asc in a murine model of concanavalin A (ConA)-induced autoimmune hepatitis (AIH). BALB/c mice received ConA, iv, (20 mg/kg), and three groups of animals were formed: (1) AIH, received only ConA; (2) AIH + Asc prophylactic, treated with Asc (1 mg/ml), ip, 30 min before of the AIH; and (3) AIH + Asc therapeutic, treated with Asc 2 h after the AIH. Plasma transaminase and immunoglobulins (measured at 8 and 24 h and 7 days after treatment) and cytokine production (IL-4, IL-10, IL-13, and IFN-γ) by splenocytes upon ConA and Asc stimulus were compared. The livers were weighed and examined histologically. In the AIH group, there was an increase in liver weight, transaminase levels, and total immunoglobulins. These parameters were reduced by 8-24 h and 7 days in the prophylactic group, but in the therapeutic group, only on day 7. The survival rate of mice in the AIH group was 38.5 %, compared to 67 % in the therapeutic Asc group. The survival rate of the animals with AIH that were prophylactically treated with Asc was 100 %. A decrease of cellular infiltration and high levels of IL-4, IL-10, and IL-13 were induced by Asc. An increase of liver fibrosis was also observed, but with less intensity with prophylactic treatment. Thus, the Ascaris components have an inhibitory effect on AIH, with an intense Th2 immune response. [ABSTRACT FROM AUTHOR]

As-p18 is produced and secreted by larvae of the parasitic nematode Ascaris suum as they develop within their eggs. The protein is a member of the fatty acid binding protein (FABP) family found in a wide range of eukaryotes, but is distinctive in that it is secreted from the synthesizing cell and has predicted additional structural features not previously seen in other FABPs. As-p18 and similar proteins found only in nematodes have therefore been designated 'nemFABPs'. Sequence-specific H, C and N resonance assignments were established for the 155 amino acid recombinant protein (18.3 kDa) in complex with oleic acid, using a series of three-dimensional triple-resonance heteronuclear NMR experiments. The secondary structure of As-p18 is predicted to be very similar to other FABPs, but the protein has extended loops that have not been observed in other FABPs whose structures have so far been solved. [ABSTRACT FROM AUTHOR]

Over a billion people are infected by Ascaris spp. intestinal parasites. To clarify functional differences among tissues of adult A. suum, we compared gene expression by various tissues of these worms by expression microarray methods. The A. suum genome was sequenced and assembled to allow generation of microarray elements. Expression of over 40,000 60-mer elements was investigated in a variety of tissues from both male and female adult worms. Nearly 50 percent of the elements for which signal was detected exhibited differential expression among different tissues. The unique profile of transcripts identified for each tissue clarified functional distinctions among tissues, such as chitin binding in the ovary and peptidase activity in the intestines. Interestingly, hundreds of gender-specific elements were characterized in multiple non-reproductive tissues of female or male worms, with most prominence of gender differences in intestinal tissue. A. suum genes from the same family were frequently expressed differently among tissues. Transcript abundance for genes specific to A. suum, by comparison to Caenorhabditis elegans, varied to a greater extent among tissues than for genes conserved between A. suum and C. elegans. Analysis using C. elegans protein interaction data identified functional modules conserved between these two nematodes, resulting in identification of functional predictions of essential subnetworks of protein interactions and how these networks may vary among nematode tissues. A notable finding was very high module similarity between adult reproductive tissues and intestine. Our results provide the most comprehensive assessment of gene expression among tissues of a parasitic nematode to date. [ABSTRACT FROM AUTHOR]

This study aimed to identify the species of helminths infecting the respiratory tract of Sus scrofa scrofa from commercial breeding and check the existence of a possible antagonistic relationship of these species with Ascaris suum. Forty wild boars were analyzed, and the genus Metastrongylus was recorded in the bronchi and bronchioles of 60 % of these, with the occurrence of the species Metastrongylus apri, Metastrongylus salmi, and Metastrongylus pudendotectus. The highest prevalence found was in M. apri (52.5 %), followed by M. salmi (20 %), and M. pudendotectus (7.5 %), registering the highest prevalence of Metastrongylus in wild boars from commercial breeding so far. M. apri was first reported parasitizing wild boars bred in captivity. There was no observed significant influence of A. suum in the mean intensity of Metastrongylus. [ABSTRACT FROM AUTHOR]

In the present study, anisakids from: tuna ( Thunnus thynnus) fattened in the Croatian farm in middle Adriatic Sea, three different feral fish species caught near tuna farm ( Trachurus trachurus, Scomber japonicus and Oblada melanura) and fish marketed in Croatia ( T. trachurus) were analysed by morphology and molecular methods. Larvae were identified to the species level by PCR restriction fragment length polymorphism and characterised by sequencing of nuclear (internal transcribed spacer) and mitochondrial (cytochrome c oxidase subunit 2) markers. The results revealed diverse Anisakidae community consisting of: Anisakis pegreffi, Anisakis simplex (s.s.) , Anisakis typica and Hysterothylacium aduncum. This is the first report of A. typica in Adriatic Sea, and also the first record of this species in T. thynnus as host in Mediterranean Sea. Molecular identification of H. aduncum found in co-infection with Anisakis larvae type I expands our knowledge of the occurrence of these taxa in the Adriatic Sea. Zoonotic Anisakidae worms found in fish from the Adriatic Sea could represent a risk to acquire parasitic infection/allergies in Croatia. [ABSTRACT FROM AUTHOR]

C-type lectins (CTLs) are a group of proteins which bind to carbohydrate epitopes in the presence of Ca, which have been described in a wide range of species. In this study, a cDNA sequence coding a putative CTL has been identified from the cDNA library constructed from the pig round worm Ascaris suum lung L3 (LL3) larvae, which was designated as A. suum C-type lectin-1 (As-CTL-1). The 510 nucleotide open reading frame of As-CTL-1 cDNA encoded the predicted 169 amino acid protein including a putative signal peptide of 23 residues and C-type lectin/C-type lectin-like domain (CLECT) at residue 26 to 167. As-CTL-1 was most similar to Toxocara canis C-type lectin-1 and 4 ( Tc-CTL-1 and 4), and highly homologous to namatode CTLs and mammalian CTLs as well, such as human C-type lectin domain family 4 member G (CLECG4). In addition, As-CTL-1 was strongly expressed in tissue migrating LL3 and the L4 larvae, which were developmental larvae stages within the mammalian host. These results suggest that A. suum larvae might utilize As-CTL-1 to avoid pathogen recognition mechanisms in mammalian hosts due to it is similarity to host immune cell receptors. [ABSTRACT FROM AUTHOR]

The cyclo-octapdepsipeptide anthelmintic emodepside exerts a profound paralysis on parasitic and free-living nematodes. The neuromuscular junction is a significant determinant of this effect. Pharmacological and electrophysiological analyses in the parasitic nematode Ascaris suum have resolved that emodepside elicits a hyperpolarisation of body wall muscle, which is dependent on extracellular calcium and the efflux of potassium ions. The molecular basis for emodepside's action has been investigated in forward genetic screens in the free-living nematode Caenorhabditis elegans. Two screens for emodepside resistance, totalling 20,000 genomes, identified several mutants of slo- 1, which encodes a calcium-activated potassium channel homologous to mammalian BK channels. Slo- 1 null mutants are more than 1000-fold less sensitive to emodepside than wild-type C. elegans and tissue-specific expression studies show emodepside acts on SLO-1 in neurons regulating feeding and motility as well as acting on SLO-1 in body wall muscle. These genetic data, combined with physiological measurements in C. elegans and the earlier physiological analyses on A. suum, define a pivotal role for SLO-1 in the mode of action of emodepside. Additional signalling pathways have emerged as determinants of emodepside's mode of action through biochemical and hypothesis-driven approaches. Mutant analyses of these pathways suggest a modulatory role for each of them in emodepside's mode of action; however, they impart much more modest changes in the sensitivity to emodepside than mutations in slo- 1. Taken together these studies identify SLO-1 as the major determinant of emodepside's anthelmintic activity. Structural information on the BK channels has advanced significantly in the last 2 years. Therefore, we rationalise this possibility by suggesting a model that speculates on the nature of the emodepside pharmacophore within the calcium-activated potassium channels. [ABSTRACT FROM AUTHOR]

Ascaris suum is a gastrointestinal nematode parasite of swines. The aim of this study was to observe Pochonia chlamydosporia fungus on biological control of A. suum eggs after fungus passage through swines gastrointestinal tract. Eighteen pigs, previously dewormed, were randomly divided into three groups: group 1, treated with the fungus isolate VC4; group 2, treated with the fungus isolate VC1 and group 3 did not receive fungus (control). In the treated groups, each animal received a 9 g single dose of mycelium mass containing P. chlamydosporia (VC1 or VC4). Thereafter, animal fecal samples were collected at the following intervals: 8, 12, 24, 36, 48, 72 and 96 h after treatment beginning and these were poured in Petri dishes containing 2% water-agar culture medium. Then, 1,000 A. suum eggs were poured into each dish and kept in an incubator at 26°C and in the dark for 30 days. After this period, approximately 100 eggs were removed from each Petri dish and morphologically analyzed under light microscopy following the ovicidal activity parameters. The higher percentage observed for isolated VC4 eggs destruction was 57.5% (36 h) after fungus administration and for isolate VC1 this percentage was 45.8% (24 h and 72 h) ( p > 0.01). P. chlamydosporia remained viable after passing through the gastrointestinal tract of swines, maintaining its ability of destroying A. suum eggs. [ABSTRACT FROM AUTHOR]

During the last 30 years, pig production in Uganda and neighbouring counties has increased markedly. Pigs are mainly kept as a source of income for small-scale farmers; however, the pig production is subject to several constraints, one of them being worm infections. A study was carried out in rural communities in Kabale District in the South Western part of Uganda in September and October 2007 in order to estimate the prevalence of gastrointestinal nematode parasites in pigs based on coprological examination. Fifty-six households were randomly selected and visited. Housing system and deworming history were recorded. Faeces was sampled from rectum of one to five pigs (age, 3-12 months) per household. A total of 106 pigs were examined coprologically of which 91% excreted nematode eggs. The following prevalences of nematode eggs were recorded: strongyles (89%), Ascaris suum (40%), Trichuris suis (17%) and spiruroid eggs (48%). On household level, rearing pigs on slatted floors in pens significantly reduced the faecal egg excretion of strongyle eggs with almost 80% ( p = 0.010) and a significant interaction between floor type and anthelmintic treatment was found for spiruroids ( p = 0.037). Fifteen T. suis egg positive pigs were selected for post-mortem examination of the gastrointestinal tract. The post-mortem examinations revealed that 93% pigs were infected with Oesophagostomum spp. (worm burden, min-max 10-2,180), 73% with A. suum (1-36), 67% with T. suis (6-58), and 20% with Hyostrongylus rubidus (worms not quantified). In general, nematode infections were widespread and polyparasitism common in pigs in Uganda. However, worm burdens were moderate which may be related to recent deworming or to the practice of rearing pigs on slatted floors in wooden elevated pens. [ABSTRACT FROM AUTHOR]

The ovicidal effect of the nematophagous fungus Pochonia chlamydosporia on eggs of Ascaris suum was tested under laboratory conditions. A. suum eggs were plated on 2% water-agar with seven fungal isolates (Isol. 5, Isol. 31, Isol. 1, VC1, Isol. 12, Isol. 22 and VC4) and control without fungus. After 5, 7, 10, 14, 15 and 21 days of incubation, approximately 100 eggs were removed from the plates and classified according to the following parameters: type 1, biochemical and physiological effect without morphological damage to the eggshell, type 2, lytic effect with morphological alteration of the eggshell and embryo and type 3, lytic effect with morphological alteration of eggshell and embryo showing hyphal penetration and internal egg colonization. The isolates effectively destroyed A. suum eggs and all types of effects were observed during the experiment. There was no variation in ovicidal capacity (type 3 effect) among the isolates ( p > 0.05) throughout the experiment. After 21 days, isolate 5 showed the highest percentages of type 3 effect (58.33%). The results indicated that P. chlamydosporia (Isol. 5, Isol. 31, Isol. 1, VC1, Isol. 12, Isol. 22 and VC4) can destroy A. suum eggs and is, therefore, a potential biological control agent of nematodes. [ABSTRACT FROM AUTHOR]

Aggregated distributions of macroparasites within their host populations are characteristic of most natural and experimental infections. We designed this study to measure the amount of variation that is attributable to host genetic factors in a pig–helminth system. In total, 195 piglets were produced after artificial insemination of 19 sows (Danish Landrace–Yorkshire crossbreds) with semen selected from 13 individual Duroc boars (1 or 2 sows per boar; mean litter size: 10.3; 5–14 piglets per litter). Starting at 10 weeks of age, piglets were repeatedly infected with the gastrointestinal helminths Trichuris suis and Ascaris suum by administering eggs in the feed for 14 weeks until necropsy. Faecal egg counts (FECs) were estimated regularly and A. suum worm burden was obtained at necropsy. Heritability calculations for log (FEC+1) at weeks 7–10 post-infection (p.i.) showed that 0.32–0.73 of the phenotypic variation for T. suis could be attributed to genetic factors. For A. suum, heritabilities of 0.29–0.31 were estimated for log (FEC+1) at weeks 7–14 p.i., whereas the heritability of log worm counts was 0.45. Strong positive genetic correlations (0.75–0.89) between T. suis and A. suum FECs suggest that resistance to both infections involves regulation by overlapping genes. Our data demonstrate that there is a strong genetic component in resistance to A. suum and T. suis infections in pigs. Identification of responsible genes would enhance our understanding of the host immune response to these common nematodes and for the closely related species (T. trichiura and A. lumbricoides) in man infecting more than a billion people.Heredity (2009) 102, 357–364; doi:10.1038/hdy.2008.131; published online 14 January 2009 [ABSTRACT FROM AUTHOR]

The trypsin inhibitor (ATI) isolated from gastrointestinal nematode Ascaris suum was tested in vitro for induction of chromosome aberrations and sister chromatid exchanges (SCE). Genotoxicity assessment of purified ATI was carried out on metaphase plates received from peripheral blood lymphocyte macroculture (48 h test of structural chromosome aberrations and 72 h test of SCE) with exogenous metabolic activation. ATI was tested in dose of 25, 50 and 100 µg per ml of culture. Kinetics of cell divisions were determined by the replication index (RI). The mitotic index (MI) was expressed as a number of metaphases per 1000 nuclei analysed. Analysis of chromosome aberrations showed that higher doses of ATI (50 and 100 µg/ml) significantly increased the frequency of chromosome aberrations (mainly of chromatid gaps and breaks) compared to the negative control. All concentrations of ATI caused a statistically significant reduction in the MI and RI. In comparison with the negative control, a significant increase in the SCE frequency was observed in all applied doses of ATI. Thus, in the presence of S9 activation, the Ascaris trypsin inhibitor showed potential clastogenic activity and inhibition of the dynamics of lymphocyte divisions. [ABSTRACT FROM AUTHOR]

The prevalence of gastrointestinal parasites in suckling piglets, weaners, fattening pigs and sows was studied from November 2001 to October 2002 on 16 free-range farms (FRF), 11 organic farms (OF) and 9 conventional farms (CF) by means of faecal examinations of composite samples. Each farm was visited four times with a 3-month interval. Infections with coccidia were found on 43.8% of the FRF, 90.9% of the OF and 66.7% of the CF. Sows had the highest prevalence, particularly on FRF (87.5%) and OF (80%). Ascaris suum was present on 50% of the FRF, 72.7% of the OF and 11.1% of the CF, whereas fattening pigs on FRF (42.9%) and OF (54.5%) had the highest prevalence. Oesophagostomum spp. were observed on 25% of the FRF, 27.2% of the OF and 22.2% of the CF. The infection was most prevalent in the sows on all farm types: 37.5% on FRF, 30% on OF and 22.2% on CF. Trichuris suis was found on 37.5% of the FRF, 36.4% of the OF and 11.1% of the CF. Again, this infection was most prevalent in the sows, particularly on the FRF (50%) and OF (30%). No other gastrointestinal parasite species were found and no clinical signs were observed. No seasonal trends could be distinguished. In many cases, when an age group on a farm was positive for a certain parasite, it remained so during the whole study. This indicates that this parasite was really ‘endemic’ on that farm. The results of this study demonstrate that the prevalence of helminth infections of pigs on farms with outdoor facilities is higher than in pigs on conventional farms. [ABSTRACT FROM AUTHOR]

The purpose of this study was to analyze computed tomographic (CT) findings of hepatic lesions due to Ascaris suum infection. CT of the liver in three patients, all of whom had immunoserologically confirmed A. suum infection, were retrospectively reviewed. Twenty-five lesions were identified in total. Two radiologists analyzed CT findings in a consensus fashion, with particular interest in the margin, shape, and location of the lesions. Hepatic lesions were ill-defined (22 of 25), small (3-35 mm; average, 11 mm), and nodular (18 of 25) or wedge (three of 25) in shape. Most were located in periportal (16 of 25) or subcapsular (six of 25) regions. Hepatic nodules due to visceral larva migrans of A. suum were located mainly in periportal or subcapsular regions, which may represent periportal eosinophilic granuloma, its pathologic feature. The results were considered to represent the pathophysiology of this entity. [ABSTRACT FROM AUTHOR]

The studies focused on the effect of 1-ppm ochratoxin A solution on the activity of some enzymes during successive embryogenesis stages of Ascaris suum. As a result of OTA-affected incubation of A suum eggs, inhibition of AcP reactions was observed throughout the embryonic development, reduction in of SDH and LDH activity during cleavage and gastrulation, and enhancement of the SDH and LDH activity was found in larvae. Moreover, inhibition of the processes of cleavage, gastrulation and organogenesis was recorded. The observed morphological and metabolic embryo disorders demonstrated teratogenic properties of the studied mycotoxin, and the presence of granules of various sizes in the developing eggs may indicate that OTA penetrated into the eggs. [ABSTRACT FROM AUTHOR]

The neutral glycosphingolipid fraction from adults of the pig parasitic nematode, Ascaris suum, was resolved into four components on thin-layer chromatography. The high-performance liquid chromatography-isolated components were structurally analysed by: methylation analysis; exoglycosidase cleavage; gas-liquid chromatography/mass spectrometry; liquid secondary-ion mass spectrometry; and, in particular, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Their chemical structures were determined as: Glc(β1-1)ceramide, Man(β1-4)Glc(β1-1)ceramide, GlcNAc(β1-3)Man(β1-4)Glc(β1-1)ceramide and Gal(α1-3)GalNAc(β1-4)GlcNAc(β1-3)Man(β1-4)Glc(β1-1)ceramide; and were characterized as belonging to the arthro-series of protostomial glycosphingolipids. No glycosphingolipid component corresponding to ceramide tetrasaccharide was detected during these analyses. The ceramide composition of the parent glycosphingolipids was dominated by the 2-(R)-hydroxy C24:0 fatty acid, cerebronic acid, and C17 sphingoid-bases: 15-methylhexadecasphing-4-enine and 15-methylhexadecaphinganine in approximately equal proportions. The component ceramide monohexoside was characterized by an additional 15-methylhexadecaphytosphingosine. Abbreviations: CDH, ceramide dihexoside; Cer, ceramide; CMH, ceramide monohexoside; CPH, ceramide pentahexoside; CTH, ceramide trihexoside; CTetH, ceramide tetrahexoside; Hex, hexose; HexNAc, N-acetylhexosamine; HPTLC, high-performance thin-layer chromatography; LSIMS, liquid secondary-ion mass spectrometry; MALDI-TOF-MS, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; N-, Nz- and A-glyco(sphingo)lipids, neutral, neutralzwitterionic and acidic glyco(sphingo)lipids, respectively [ABSTRACT FROM AUTHOR]

The small- and large-subunit mitochondrial ribosomal RNA genes (mt-s-rRNA and mt-1-rRNA) of the nematode worms Caenorhabditis elegans and Ascaris suum encode the smallest rRNAs so far reported for metazoa. These size reductions correlate with the previously described, smaller, structurally anomalous mt-tRNAs of C. elegans and A. suum. Using primer extension analysis, the 5′ end nucleotides of the mt-s-rRNA and mt-1-rRNA genes were determined to be adjacent to the 3′ end nucleotides of the tRNA and tRNA genes, respectively. Detailed, consensus secondary-structure models were constructed for the mt-s-rRNA genes and the 3′ 64% of mt-1-rRNA genes of the two nematodes. The mt-s-rRNA secondary-structure model bears a remarkable resemblance to the previously defined universal core structure of E. coli 16S rRNA: most of the nucleotides that have been classified as variable or semiconserved in the E. coli model appear to have been eliminated from the C. elegans and A. suum sequences. Also, the secondary structure model constructed for the 3′ 64% of the mt-1-rRNA is similar to the corresponding portion of the previously defined E. coli 23S rRNA core secondary structure. The proposed C. elegans/ A. suum mt-s-rRNA and mt-1-rRNA models include all of the secondary-structure element-forming sequences that in E. coli rRNAs contain nucleotides important for A-site and P-site (but not E-site) interactions with tRNAs. Sets of apparently homologous sequences within the mt-s-rRNA and mt-1-rRNA core structures, derived by alignment of the C. elegans and A. suum mt-rRNAs to the corresponding mt-rRNAs of other eukaryotes, and E. coli rRNAs were used in maximum-likelihood analyses. The patterns of divergence of metazoan phyla obtained show considerable agreement with the most prevalent metazoan divergence patterns derived from more classical, morphological, and developmental data. [ABSTRACT FROM AUTHOR]

The intestinal epithelium of Ascaris suum consists of a single layer of tall columnar epithelial cells that rest on a thick basal membrane in contact with the pseudocoelomic cavity. Experiments were conducted on glutaraldehyde-fixed tissue to ascertain the nature of the electronegative charges associated with both the apical microvillar surface and basal membrane. A strong electronegative charge was demonstrated on the microvillar surface and basal membrane with ruthenium red and cationic ferritin staining. The ionic nature of ferritin binding was demonstrated with poly-L-lysine, a polycation that interacts with anionic groups on the membrane and thus blocks the subsequent binding of ferritin. Tissue thus treated was devoid of reaction product. Methylation with diazomethane completely abolished staining. Since the stronger acidic groups of sulfates or phosphates would not be protonated under the conditions employed in this study, and therefore susceptible to methylation, staining by ferritin is thought to be due to its interaction with carboxyl groups. Prior enzymatic treatment of tissue with neuraminidase or phospholipase C had no effect on subsequent ferritin binding. Tissue exposed to colloidal iron at various pH values showed maximal reactivity at a pH of 2.5 or above. Above pH 2.5, the dissociation of protons from free carboxyl groups of protein-bound amino-acid residues with pK's of 3.8 and 4.2 would be maximal, and the ionized carboxyl groups are then available to interact with iron micelles. These results suggest the presence of weaker acidic groups, such as the carboxyl groups of acidic amino acids or uronic acid residues. The stronger acidic groups of sialic acid and the esterified sulfate groups, if present, contribute only minimally to overall staining. These results demonstrate that a high electronegative charge density exists, despite the apparent lack of sialic acid. Staining is believed to be due to carboxyl groups of acidic amino acids and/or carboxyl groups or uronic acid residues. [ABSTRACT FROM AUTHOR]

A system is described for the study of activation and motility of Ascaris spermatozoa in vitro. Activation was accomplished by addition of the sperm-activating substances (SAS), extracted from the male accessory gland, to cells incubated in phosphate-buffered saline (pH 7.4) at 37-39° C under anaerobic conditions (95% N, 5% CO). Activation is characterized by a change from spherical to ameboid shape with coalescence of the refringent granules. The normal ameboid spermatozoa bear several stubby and needle-like filopodia at the lamellipodial margin. Within the lamellipodium are bundles of microfilament-like structures extending toward the pseudopodial membrane and concentrating within the needle-like filopodia. These filopodia exhibit a pendulous, sweeping motion with subsequent retraction and disappearence within the main lamellipodium. Membranes of the ameboid cells interact at the pseudopodial regions with partial fusion, as suggested by apparent membrane breakdown between interdigitating portions of the pseudopodia. Activation is complete in 5-15 min, is totally inhibited at 4° C and/or by an atmospheric environment, but can be reinitiated by transfer to anaerobic conditions at 22-9° C. Activation also requires favorable pH (6.8-8.7) and continual exposure to sufficiently high sodium concentrations (134-154mM), i.e., lowering of sodium concentration to 10 mM causes irreversible inactivation. Sodium may be replaced by potassium or lithium but not by Tris or sucrose. Proteinases (10 μg/ml) can act as activators even though SAS lack detectable proteolytic activity against azoalbumin, azocasein, TAME and BTEE and SAS activation was not inhibited by TLCK or soybean trypsin inhibitor. [ABSTRACT FROM AUTHOR]

Receptors for Concanavalin A (Con A), were localized on the intestinal epithelium of the nematodes Ascaris suum and Parascaris equorum. Fixed tissue incubated in H-Con A showed labeling of the microvilli surface and basal membrane. Using Con A coupled with peroxidase, the tips of the microvilli of Ascaris suum and the tips and lateral surfaces of Parascaris equorum were stained. The basal membrane of both species was also labeled. No labeling was observed on control tissue incubated without Con A or on tissue incubated with Con A to which α-methyl-D-mannoside was added. [ABSTRACT FROM AUTHOR]

A large number of FMRFamide-related peptides (FaRPs) are found in nematodes, and some of these are known to influence tension and contractility of neuromuscular strips isolated from Ascaris suum body wall. Relaxation of these strips has been noted with five nematode FaRPs. The inhibitory actions of SDPNFLRFamide (PF1) and SADPNFLRFamide (PF2) appear to be mediated by nitric oxide, as previously demonstrated with inhibitors of nitric oxide synthase (NOS). This present study showed that the effects of PF1 were also dependent on external Ca and were reduced by the Ca-channel blocker verapamil, observations consistent wirh the finding that nematode NOS is Ca-dependent. KSAYMRFamide (PF3), KPNFIRFamide (PF4) and KNAFIRFamide (an alanine substituted analog of KNEFIRFamide, AF1, termed AAF1) also relaxed A. suum muscle strips, but these responses were not affected by NOS inhibitors. PF3 inhibited the activity of strips prepared from the dorsal side of the worm, but contracted ventral strips. Both effects were dependent on the presence of ventral/dorsal nerve cords (unlike PF1/PF2) and were attenuated in medium which contained high K or low Ca. PF4-induced muscle relaxation and hyperpolarization were independent of nerve cords, but were reversed in Cl-free medium, unlike PF1 or PF3. The PF4 effect physiologically desensitized muscle strips to subsequent treatment with PF4 and/or GABA. However, PF4 and GABA were not synergistic in this preparation. The effects of GABA, but not PF4, were reduced in muscle strips treated with the GABA antagonist, NCS 281-93. Following PF4 (or GABA) relaxation, subsequent treatment with higher doses of PF4 caused muscle strip contraction. AAF1 was found to relax muscle strips and hyperpolarize muscle cells independently of the ventral and dorsal nerve cords, K, Ca, and Cl-, and mimicked the inhibitory phase associated with the exposure of these strips to AF1. On the basis of anatomical and ionic dependence, these data have delineated at least four distinct inhibitory activities attributable to nematode FaRPs. Clearly, a remarkably complex set of inhibitory mechanisms operate in the nematode neuromuscular system. [ABSTRACT FROM AUTHOR]

The malic enzyme gene of Ascaris suum was cloned into the vector pTRC99a in two forms encoding alternative arnino-termini. The resulting plasmids, pMEAl and pMEA2, were introduced into Escherichia coli NZN111, a strain that is unable to grow fermentatively because of inactivation of the genes encoding pyruvate dissimilation. Induction of pMEAl, which encodes the native animoterminus, gave better overexpression of malic enzyme, approx 12-fold compared to uninduced cells. Under the appropriate culture conditions, expression of malic enzyme allowed the fermentative dissimilation of glucose by NZN111. The major fermentation product formed in induced cultures was succinic acid. [ABSTRACT FROM AUTHOR]

The permeability of organic anions (produced from anaerobic fermentation of glucose) through a nonselective membrane Cl channel was examined. Single channel recording techniques were used to study the permeabilities of the anions: oxalate, succinate, oxaloacetate, malate, lactate and pyruvate in Ascaris muscle cell membranes. All of the anions, except malate, were found to be conducted through the channel. The relative permeability of most anions could be predicted from the component structure of the anions. The failure of the channel to conduct malate prevents an energy drain on the cell. These studies further the hypothesis that a Cl channel functions to transport waste organic anions across the cell membrane. This mechanism does not require specific exchange carriers for the anions. Channels with properties like the nonselective anion channels of Ascaris, are suitable for transport of carboxylic anions through cell membranes, down a concentration or potential gradient. [ABSTRACT FROM AUTHOR]

Plasma membrane vesicles prepared from the bag region of the somatic muscle cell of the parasite Ascaris suum contain a large conductance, voltage-sensitive, calcium-activated chloride channel. The ability of this channel to conduct a variety of carboxylic acids, a number of which are products of anaerobic respiration, was investigated using the patch-clamp technique and isolated inside-out patches of muscle membrane. The channel has a conductance of 140 pS in symmetrical 140 m m chloride. Replacement of internal chloride with various carboxylic acids (140 m m) caused large hyperpolarizing shifts in the reversal potential. Permeability ratios, relative to chloride, were calculated for each acid. The relationship between permeability ratio and ionic size is inverse and linear predicting a pore diameter of 6.55 Å. This simple relationship was not observed between ionic size and conductance. Calculation of the transition state energy required to transfer a single methyl group from aqueous phase to the binding site afforded a value that was low but favorable, indicating a cationic binding site of low field strength. As the channel is able to open fully at the resting membrane potential of Ascaris and is permeable to fatty acids produced by anaerobic respiration, the possible role of this channel in the removal of metabolic products across the muscle membrane is discussed. [ABSTRACT FROM AUTHOR]

Plasma membrane vesicles prepared from the bag re gion of the somatic muscle cell of the parasite Ascaris suum contain a large conductance, voltage-sensitive, calcium-activated chloride channel. The ability of this channel to conduct a variety of anions has been investigated using the patch-clamp technique on isolated inside-out patches of muscle membrane. Symmetrical Cl solutions (140 mm) produced single-channel I/V plots with reversal potentials of 0 mV, substitution of bath Cl by 140 mM NO, Br and I caused depolarizing shifts in the reversal potentials. Replacement of the internal Cl by F (140 mM) caused a large hyperpolarizing shift in the reversal potential. The channel dis played a permeability sequence of I > Br = NO> Cl > F which differed from the corresponding conductance sequence Cl > NO = Br = I > F. The ionic environment within the channel pore has been investigated using Reuter and Stevens (1980) plots to describe the selectivity and 'fluidity' of the channel pore. In addition, the approach of Wright and Diamond (1977) was employed to estimate the number of cationic binding sites within the channel pore. The channel is relatively fluid but the number of cationic binding sites varies inversely with the ionic radius of the anion from 2.15 for F to 0.89 for the large planar anion NO [ABSTRACT FROM AUTHOR]