Differential Change in the Prevalence of the Ascaris, Trichuris and Clonorchis infection Among Past East Asian Populations

As we learn more about parasites in ancient civilizations, data becomes available that can be used to see how infection may change over time. The aim of this study is to assess how common certain intestinal parasites were in China and Korea in the past 2000 years, and make comparisons with prevalence data from the 20th century. This allows us to go on to investigate how and why changes in parasite prevalence may have occurred at different times. Here we show that Chinese liver fluke (Clonorchis sinensis) dropped markedly in prevalence in both Korea and China earlier than did roundworm (Ascaris lumbricoides) and whipworm (Trichuris trichiura). We use historical evidence to determine why this was the case, exploring the role of developing sanitation infrastructure, changing use of human feces as crop fertilizer, development of chemical fertilizers, snail control programs, changing dietary preferences, and governmental public health campaigns during the 20th century.

Inactivation of Ascaris suum in a biodrying compost system

Pathogen contamination of waterways is a serious concern in dairy farming areas where livestock waste is applied to agricultural fields. As an alternative, a biodrying composting system dries collected livestock waste, reduces the strong odors, and has been proposed as a means of reducing, and even eliminating pathogens present in the waste. Therefore, the survival of pathogens in a biodrying composting system was investigated. Dairy farm livestock waste was piled in a biodrying storage shed where forced aeration and natural decomposition processes heated a major portion of the waste pile to temperatures exceeding 55 degrees C. Ascaris suum eggs were used as the surrogate species and inoculated into special chambers and placed at three different elevations at different intervals along the length of the pile. Control chambers were stored in water at 4 degrees C in the laboratory. Both compost and control chambers were removed at Day 4, 8, 12, 16, and 20. The eggs were extracted from the chamber medium and analyzed for viability. No viable eggs were recovered from any of the chambers removed from the compost pile, while >or=90% viability was observed in the control chambers. High temperatures and continued drying were the major contributing factors to the inactivation of the helminth eggs. The complete inactivation of A. suum eggs by the biodrying process encourages the storage and treatment of manure to high temperatures and reduced moisture conditions before field spreading to reduce the risk of harmful pathogens contaminating waterways and potential drinking water supplies.

Structure of MFP2 and its function in enhancing MSP polymerization in Ascaris sperm amoeboid motility

The simplicity and specialization of the cell motility machinery of Ascaris sperm provides a powerful system in which to probe the basic molecular mechanism of amoeboid cell motility. Although Ascaris sperm locomotion closely resembles that seen in many other types of crawling cell, movement is generated by modulation of a cytoskeleton based on the major sperm protein (MSP) rather than the actin present in other cell types. The Ascaris motility machinery can be studied conveniently in a cell-free in vitro system based on the movement of plasma membrane vesicles by fibres constructed from bundles of MSP filaments. In addition to ATP, MSP and a plasma membrane protein, reconstitution of MSP motility in this cell-free extract requires cytosolic proteins to orchestrate the site-specific assembly and bundling of MSP filaments that generates locomotion. One of these proteins, MFP2, accelerates the rate of movement in this assay. Here, we describe crystal structures of two isoforms of MFP2 and show that both are constructed from two domains that have the same fold based on a novel, compact beta sheet arrangement. Patterns of conservation observed in a structure-based analysis of MFP2 sequences from different nematode species identified regions that may be putative functional interfaces involved both in interactions between MFP2 domains and also with other components of the sperm motility machinery. Analysis of the growth of fibres in vitro in the presence of added MFP2 indicated that MFP2 increases the rate of locomotion by enhancing the effective rate of MSP filament polymerization. This observation, together with the structural data, suggests that MFP2 may function in a manner analogous to formins in actin-based motility.

Electron miscroscopy and histochemical studies on four Egyptian helminthes eggs of medical importance

By SEM the Fasciola gigantica egg is ovoid with a small knob like operculum, while the egg of Heterophyes heterophytes is broad oval with the operculum more tapering. The egg shell of fertilized Ascaris lumbricoides has interconnected ridges and peak-like projections, while the egg of Enterobius vermicularis is flattened with a thicker margin at the curved side. By TEM, Fasciola egg shell consists of fine reticulum fibrils of three layers. The outer lipoprotein of perivitelline membrane beneath which 2 membranes separated by inclusions, middle of protein globules and inner lipoprotein layer with minute electron-dense granules of melanin or polymer origin, in some parts of the shell giving the egg its brown coloration. The Heterophyes egg shell is more or less similar to that of Fasciola but lacking the minute electron-dense granules. The egg shell of Ascaris has outer ulterine layer with three consecutive layers, basal lipoprotein layer and the inner lipid or ascaroside layer which is the most resistant layer. The Enterobius egg shell consists of five layers, external uterine, internal uterine, vitelline, chitinous and lipid layer. Histochemically, Fasciola egg shell consists of nine amino-acids, and that of Heterophyes consists of ten amino acids. In Ascaris, the lipid layer characteristically consists 25% protein and 75% lipid. The histochemical examination of Enterobius as a detailed example, showed different degrees of reactions with mercuric bromophenol blue, diazotization coupling, Sakaguchi reaction, Sudan black and Mallory's triple stain. Temperature showed marked effect on eggs survival. Eggs of Fasciola and Heterophyes withstand more low temperatures but those of Ascaris and Enterobius withstand more high ones. There are marked correlations between the egg shell constitution, histochemical compositions on one hand and water permeability and egg dryness on the other hand. The results were photographed and discussed.

Modelling and estimation of physical parameters in a sludge drying system

In this paper is presented the study of a Sludge Drying System used to kill pathogenic organisms living in sludge. The system is modeled and the physical parameters thermal capacity, thermal resistance and thermal time constant are estimated using conventional estimation methods.

Posterior end mark, a novel maternal gene encoding a localized factor in the ascidian embryo

Ascidian embryogenesis is regarded as a typical ‘mosaic’ type. Recent studies have provided convincing evidence that components of the posterior-vegetal cytoplasm of fertilized eggs are responsible for establishment of the anteroposterior axis of the embryo. We report here isolation and characterization of a novel maternal gene, posterior end mark (pem). After fertilization, the pem transcript is concentrated in the posterior-vegetal cytoplasm of the egg and later marks the posterior end of developing ascidian embryos. Despite its conspicuous localization pattern, the predicted PEM protein shows no significant homology to known proteins. Overexpression of this gene by microinjection of synthesized pem mRNA into fertilized eggs results in development of tadpole larvae with deficiency of the anteriormost adhesive organ, dorsal brain and sensory pigment-cells. Lineage tracing analysis revealed that the anterior epidermis and dorsal neuronal cells were translocated posteriorly into the tail region, suggesting that this gene plays a role in establishment of anterior and dorsal patterning of the embryo. The ascidian tadpole is regarded as a prototype of vertebrates, implying a similar function of pem in vertebrate embryogenesis.

Reconstitution in vitro of the motile apparatus from the amoeboid sperm of Ascaris shows that filament assembly and bundling move membranes

We have developed an in vitro motility system from Ascaris sperm, unique amoeboid cells that use filament arrays composed of major sperm protein (MSP) instead of an actin-based apparatus for locomotion. Addition of ATP to sperm extracts induces formation of fibers approximately 2 microns in diameter. These fibers display the key features of the MSP cytoskeleton in vivo. Each fiber consists of a meshwork of MSP filaments and has at one end a vesicle derived from the plasma membrane at the leading edge of the cell. Fiber growth is due to filament assembly at the vesicle; thus, fiber elongation results in vesicle translocation. This in vitro system demonstrates directly that localized polymerization and bundling of filaments can move membranes and provides a powerful assay for evaluating the molecular mechanism of amoeboid cell motility.

GABA-immunoreactive neurons in the nematode Ascaris

gamma-Aminobutyric acid (GABA) immunoreactive neurons in the cephalic, somatic, and caudal regions of the Ascaris nervous system were visualized with serial section and whole-mount GABA immunocytochemistry. In the ventral and dorsal nerve cords, GABA-like immunoreactivity (GLIR) is localized to the neurites and cell bodies of identified inhibitory motor neurons and to two fibers, one in each cord, that arise from neurons in the nerve ring. GLIR is absent from identified excitatory motor neurons and from ventral cord interneurons. In neurons containing GLIR, immunoreactivity was present throughout the cell, which argues against an exclusive localization of GABA at conventional synapses. In whole mounts, ten GABA-immunoreactive neurons were present in the cephalic region. These include four nerve ring-associated cells (the RME-like cells), two bilaterally symmetrical pairs of lateral ganglia neurons (the amphid-GABA and deirid-GABA cells) and one bilaterally symmetrical pair of ventral ganglion cells (the VG-GABA cells). In sections, the RME-like cells and the VG-GABA cells were consistently stained through the cephalic region. However, anti-GABA staining of the lateral ganglia cells in sections was light, thus suggesting that they contain less GLIR than the other more intensely stained GABA-immunoreactive neurons. In the caudal region, a single GABA-immunoreactive neuron was present in the dorsal rectal ganglion. Our data suggest that these ten cephalic neurons, and a single dorsal rectal ganglion neuron, use GABA as a neurotransmitter.

Immunocytochemical demonstration of a neuropeptide in Ascaris suum (Nematoda) using an antiserum to FMRFamide

A FMRFamide-like peptide has been detected in the nematode Ascaris suum, using the peroxidase-anti-peroxidase (PAP) immunocytochemical technique. Positive reactions were obtained in both the central nervous system and the peripheral nervous system of the worm, the strongest reactions being in the anterior nerve ring, the cephalic papillary ganglia, the lateral ganglia and the dorso-rectal ganglion. Immunoreactivity was observed along the length of the main nerve cords of the worm and, to a lesser extent, in the pharyngeal nerve cords. The possible role of this neuropeptide in the physiology of the nematode is discussed.

Ascaris suum: immunoperoxidase and fluorescent probe analysis of host proteases and parasite proteinase inhibitors in developing eggs and second stage larvae

Live Ascaris suum females were incubated in medium containing chymotrypsin liganded to fluorescein-5-isothiocyanate, and eggs in the parasite's genital tract took up the probe and fluoresced. Eggs passed by these worms into the medium containing fluorescent probe retained their fluorescence in formaldehyde-saline and by 65 days had developed into second stage infective larvae. Eggs passed naturally by untreated worms were incubated in media containing fluorescent probes and all of the eggs exposed to chymotrypsin liganded to fluorescein-5-isothiocyanate were extensively labeled. Control eggs were labeled sporadically and less intensely, indicating specificity in the uptake of environmental proteins. Chymotrypsin from the parasite's environment can bind to A. suum eggs, and this occurs both inside the worm's genital tract and outside of the parasite. Immunoperoxidase studies showed that IgG developed against chymotrypsin or against A. suum chymotrypsin/elastase isoinhibitors A or C, binds to antigens in cross sections of second stage larvae and their egg shell coats. This suggests that host chymotrypsin is retained during development and may be complexed to A. suum isoinhibitors A and C.

The survival of parasite eggs throughout the soil profile

An experiment using lysimeters suggested that the eggs of Taenia saginata and Ascaris lumbricoides survive for only a short time when applied to pasture in sewage sludge. However, a subsequent experiment which followed the survival of eggs throughout the soil profile demonstrated that some T. saginata eggs could still be found at 200 days on the soil surface, and that survival increased down the profile. Rainfall is shown to be able to wash eggs into the soil where they may be afforded protection from radiation and desiccation; this may have little epidemiological significance.

Identification of excitatory and inhibitory motoneurons in the nematode Ascaris by electrophysiological techniques

A physiological preparation in which it is possible to record responses in muscle to stimulation of single motoneurons of the nematode Ascaris lumbricoides is described. With this preparation we have determined the physiological sign (E or I; excitatory or inhibitory) of the neuromuscular synapses of 21 identified motoneurons--12 are excitatory and 9 inhibitory. Ascaris motoneurons had previously been classified by morphological criteria into seven classes (Stretton, A. O. W., R. M. Fishpool, E. Southgate, J. E. Donmoyer, J. P. Walrond, J. E. R. Moses, and I. S. Kass (1978) Proc. Natl. Acad. Sci. U. S. A. 75: 3493-3497). Physiological studies were performed on members of five of these classes. Three classes of neurons (DE1, DE2, and DE3) are excitatory to dorsal muscle cells. Two classes (DI and VI) are inhibitory neurons which innervate the dorsal and ventral muscle cells, respectively. The motoneurons in Caenorhabditis elegans (White, J. E., E. Southgate, J. N. Thomson, and S. Brenner (1976) Philos. Trans. R. Soc. Lond. (Biol.) 275: 327-348) can be divided into seven morphological classes which are very similar to those in Ascaris. Based upon the structure-function correlation in Ascaris, we have predicted which motoneurons are excitatory and which are inhibitory in C. elegans.

Effect of levamisol on tissues of Ascaris lumbricoides

Levamisol which is highly effective against Ascaris infections, was shown to produce degenerative changes in the intestine and the reproductive system of the worm. Worms that were not expelled by treatment produced only nonviable eggs which could not develop in vitro. Levamisol is thus shown to be not only a highly curative drug, but a compound of significant epidemiological importance.

Structure and physiological activity of the motoneurons of the nematode Ascaris

The nervous system of the nematode worm Ascaris contains about 250 nerve cells; of these, the motoneurons consist of five segmental sets, each containing 11 cells. Morphologically, the motoneurons can be divided into seven different types. Their geometry is simple: some are unbranched, others have one branch point, and the most complex have two. There is no neuropil in the nerve cords; synapses are made by axo-axonal contact or onto short spines. These features enable us to study the anatomy and physiology of the system with a degree of completeness that would be difficult in other systems. The physiological activity of five of the motoneurons has been investigated, three being excitatory and two inhibitory. The excitatory motoneurons receive input from intersegmental interneurons. The inhibitory motoneurons do not receive input from the interneurons; instead they receive their input from the excitatory motoneurons in a circuit that can mediate reciprocal inhibition between the dorsal and the ventral musculature.

[Experimental studies on anthelmintics (XXVI). Biochemical and pharmacological studies of 4-iodothymol on Ascaris lumbricoides suum]

We have shown previously that 4-iodothymol (IT) produces a contraction in Ascaris muscle, probably due to the myogenic action. In this paper, the effects of IT on the carbohydrate metabolism in Ascaris muscle have been investigated in comparison with those of hexylresorcinol (Hex), santonin (S) and piperazine (Pip). (1) Hex (200 approximately 400 mug/ml) showed a strong nonspecific inhibition on the formation of succinate from fumarate in muscle homogenate, the phosphofructokinase (PFK) activity in cytoplasm, and the electron transfer activity in mitochondria. (2) S(100 approximately 400 mug/ml) and Pip (100 approximately 400 mug/ml) were inneffective on these activities. (3) IT inhibited the formation of succinate from glucose and fumarate in muscle homogenate (100 approximately 400 mug/ml), the PFK activity in cytoplasm (400 mug/ml), and the mitochondrial succinate oxidase system (25 approximately 400 mug/ml). These results suggest that IT elicits the wormcidal action by inhibiting the energy metabolism of Ascaris muscle mitochondria.

Morphology and behaviour of sex chromosomes during meiosis in Ascaris suum

The morphology and behaviour of sex chromosomes was studied in A. suum during meiosis. It was found that the five sex chromosomes have their proper characteristic. The largest is submetacentric, of 2 microns mean length. The second largest is acrocentric, mean length of 1.4 mu. The third largest is metacentric, 1.2 mu mean length. The fourth and the fifth are metacentric, of mean length of 1 mu. In primary and secondary spermatocyte cells the sex chromosomes are close to each other, most often in the peripheral part of the cell. During anaphase I the pentad sex chromosomes lie freely between the two sister cells. It is assumed that in anaphase II the five sex chromosomes divide equally and are regularly distributed in the daughter cells. It was found that the chromosomes set of female Ascaris in metaphase I contains 24 bivalent chromosomes n = 24 and of male Ascaris 19 bivalents and 5 univalents. It is assumed that the univalent chromosomes, found in spermatocyte cells, determine sex.

Ultrastructure of dyads in muscle fibers of Ascaris lumbricoides

The dyads of Ascaris body muscle cells consist of flattened intracellular cisternae applied to the sarcolemma at the cell surface and along the length of T-tubules. In specimens prepared by conventional methods (glutaraldehyde fixation, osmium tetroxide postfixation, double staining of sections with uranyl acetate and lead hydroxide), both the sarcolemma and the limiting membrane of the cisterna exhibit unit membrane structure and the space between them is occupied by a layer of peg-shaped densities which is referred to as the subsarcolemmal lamina. The lumen of the cisterna contains a serrated layer of dense material referred to as the intracisternal lamina. In specimens fixed in glutaraldehyde, dehydrated, and then postfixed in phosphotungstic acid, with no exposure to osmium tetroxide or heavy metal stains, the membranous components of the dyads appear only as negative images, but the subsarcolemmal and intracisternal laminae still appear dense. Except for the lack of density in membranes and in glycogen deposits, the picture produced by the latter method is very much like that of tissue prepared by conventional methods.

Parasites as biological models

The value of metazoan parasites as models for the investigation of fundamental biological phenomena is discussed. The fields in which they are of particular value include: immunology, neuromuscular physiology, nucleo-cytoplasmic relationships, genetics, cyto-differentiation, comparative biochemistry.

After reviewing some examples of experimental organisms in trematodes and nematodes, the cestode, Echinococcus granulosus, in particular, is examined as a model.

Problems of particular interest in this organism are: the function of the rostellar gland, whose cells release a secretion which has its origin in the nuclei of these cells; the mode of action of the suckers, which in vivo are thought to remain in a state of sustained contraction; the mode of digestion at the host–parasite interface—membrane digestion appears to be involved; the various modes of membrane transport through the tegument; factors controlling cystic or strobilar differentiation, a problem viewed in the light of the Jacob–Monad model of gene action.

A hypothetical control circuit for differentiation of the stages in parasite life-cycles in general is also put forward.

Some preliminary experiments on the in vitro culture of Taenia serialis, are described. The factors controlling differentiation into cystic or strobilar directions appear to be generally similar to those which operate for Echinococcus granulosus.

It was stressed that many other species of parasites could also serve as models for investigating similar or related problems.

Some of the studies described here were supported by grants from the Australian Wool Board, the U.S. Public Health Service (Grant no. A 107452–02) and the Rural Credits Development Fund.

I am grateful to Mr D. Heath for the provision of the micrographs of Taenia pisiformis and T. serialis in P1. 2, figs. 2, 3.