Male Schistosoma Research Articles

Schistosoma mansoni tegumental appendages: scanning microscopy following thiocarbohydrazide-osmium preparation.

Scanning photographs of the surface of normal adult male and female Schistosoma mansoni are given. The specimens were prepared using a thiocarbohydrazide technique which facilitates the binding of osmium. The resultant deep penetration of osmium preserves surface detail for electron reflection. The schistosomal tegument is characterized by a variety of surface bosses and spines. The function of certain of these is thought to be tactile or as chemoreceptors. Numerous tegumental pores surrounding setae in surface tubercles are shown. Clefts in the inner aspect of the gynecophoral canal are also seen. The excretory pore in both male and female is shown, along with a cluster of receptors at the terminus of the gynecophoral groove. Such grouped receptors may function to indicate position of the worm in copula.

Schistosoma mansoni: Direct method for simultaneous recording of electrical and motor activity

A method utilizing suction electrodes for simultaneous recording of electrical activity and motility of adult male Schistosoma mansoni is described. Spontaneous body contractions, similar to peristaltic waves, occur in an approximately rhythmic manner. Surface electrical potentials are associated with these contractions. Stretch increases the rate of spontaneous contractions. 5-Hydroxytryptamine at a concentration of 10 −6 M increases the contraction rate and also the complexity of the contractions. Carbachol at 10 −5 M decreases the rate at which contractions occur and also decreases the complexity of each contraction burst and at 10 −4 M completely suppresses activity.

Scanning Electron Microscopy of Integumental Surfaces of Schistosoma intercalatum

Scanning electron microscopy was employed to study critical point dried Schistosoma intercalatum adults at 120 to 6,000 X magnifications. Well-developed integrumental elevations, or bosses, with variable spination account for the roughness of the male schistosome. The female is relatively smooth even though it possesses minute spines on the posterior part of the body. SEM reveals that the gynecophoral canal of the male, especially the presence of a gynecophoral fold, provides an effective means for clasping the female when in copula.

The Timing of Reproductive Cell Development and Movement in Schistosoma mansoni, S. japonicum, and S. haematobium, Using Techniques of Autoradiography and Transplantation

Tritiated thymidine was incorporated into gonial and vitelline cells of male and female Schistosoma mansoni, S. japonicum, and S. haematobium after 2 hr of incubation. Spermatogonial cells developed into labeled mature sperm after 6 days of transplantation in all species. Insemination of females was detected on the same day indicating copulation is frequent. Oogonia labeled in the initial incubation matured into primary oocytes after 7 days of transplantation for S. mansoni and S. haematobium and after 6 days in S. japonicum. Cytoplasmic thymidine label was observed after 2-hr incubations in the primary oocytes of all species. Initial label in the vitellaria was scattered and heavy. After 3 days of transplantation, label was considerably diluted and by day 6 was undetectable in vitelline glands. These times for development and movement of reproductive cells are considered to be standards against which the effects of stressful conditions on the reproductive system can be assessed.

Scanning Electron Microscopy of the Integumental Surfaces of Schistosoma haematobium

The integumental surfaces of critical point dried S. haematobium were studied by scanning electron microscopy at 34 to 8,000 magnifications. There are marked differences between the surface structures of male and female as well as from one part of the same parasite to another. The surface of the male schistosome is moderately rough while that of the female is relatively smooth. SEM reveals certain basic features such as spines in the oral sucker and the acetabulum of both sexes which may facilitate rasping and/or attachment of the parasite for residence in the bloodstream of the definitive host. The lining of the gynecophoral canal is roughened by minute spines. The presence of a gynecophoral fold may enhance anchorage of the female in the grasp of the male. The significance of visualization of surface features by SEM as a means for differentiating species is not yet known.

Membrane transport in Schistosoma mansoni: Transport of amino acids by adult males

The mechanisms by which adult male Schistosoma mansoni transport amino acids have been investigated using radioactive amino acids during 2-min incubation times. The transport constants ( K t ) for mediated uptake of glycine, proline, methionine, arginine, glutamate, and tryptophan were calculated to be 0.60-1.05, 1.67-1.98, 2.0, 0.10-0.35, 0.30-0.50, and 0.5-1.0 m M, respectively. Maximal velocities ( V max) were 5.5–7.5, 25, 6.4, 1.5-2.0, 2.5, and 3.0–6.0 μmoles absorbed/g worm protein/2 min, respectively. Cysteine is taken up solely by diffusion. Proline uptake is unique in that no significant diffusion component was found. The other amino acids studied were absorbed by diffusion as well as by specific transport systems. In the 2-min incubation periods employed glycine, proline, glutamate, and methionine were not significantly metabolized indicating that the uptake studies using these substrates reflect transport. Metabolism of the other amino acids used in these studies was not examined. The specificity of the transport systems was studied by testing the inhibitory effects of various amino acids on the uptake of each of the amino acids studied. The results suggest the presence of at least five transport systems. There is a highly specific transport locus for proline, and one for acidic amino acids. There are probably at least two transport systems, each of broad and overlapping specificity, for most of the neutral amino acids. Basic amino acids also appear to be taken up by complex transport systems, at least one of which overlaps with the neutral sites. The results are discussed with respect to the nutrition of the parasite and the host-parasite relationship.

Anatomical localization of glucose uptake by Schistosoma mansoni adults

An apparatus was used to determine whether glucose enters adult Schistosoma mansoni through the oral sucker or the integumental surfaces. The results confirm the view that the integument is the primary site of glucose absorption in S. mansoni. Incubation of the parasites in 5-hydroxytryptamine (prior to insertion into the apparatus) depleted glycogen stores and increased glucose uptake. The demonstration of integumental uptake of glucose by female worms is consistent with the hypothesis that in copula the male schistosome provides glucose to the female.

Schistosomatium douthitti: Effects of thyroxine

Thyroxine-treated flukes showed increased tetrazolium reductase and cytochrome oxidase activities in histochemical preparations. Single male, single female, and pairs of S. douthitti, as well as cercariae of this species, consumed more oxygen when treated with thyroxine than did controls. The same effect was observed in all other invertebrates examined ( Haematoloechus sp., Dugesia sp., Tetrahymena pyriformis, and an unidentified strigeoid species of cercaria). Both male and female schistosomes from hyperthyroid hosts are significantly larger than flukes from normal mice ( P < 0.025). This condition prevailed whether the hyperthyroid state was established prior to cercarial penetration or after schistosomular migration through the lungs. S. douthitti adults from surgically thyroidectomized rats were significantly smaller than flukes from sham-operated sibling controls ( P < 0.01). An accelerated death rate was also observed in hyperthyroid mice infected with S. douthitti. Female schistosomes from unisexual infections were significantly smaller ( P < 0.1) than those from bisexual infections, confirming Short's (1952) report.

Schistosoma mansoni and Schistosoma japonicum: Comparison of selected aspects of carbohydrate metabolism

1.1. The production of CO2 from selected carbohydrates by male and female Schistosoma mansoni and S. japonicum was studied.2.2. The largest amounts of CO2 were produced from glucose, fructose and mannose while lesser amounts were provided from galactose, maltose, lactose, glucosamine and mannitol.3.3. Both sex- and species-related differences were found.4.4. The differences observed in CO2 production from individually labeled carbons of the glucose molecule and quantitative differences in this incorporation of the glucose carbons into glycogen also suggested quantitative differences in the metabolic pathways between species and sexes.

Comparison of the characteristics of acetylcholinesterase present in four species of Schistosoma

1.1. The acetylcholinesterase (EC. 3.1.1.7) of adult male and female Schistosoma mansoni, S. haematobium, S. bovis and S. mattheei was characterized using acetyl-1-14C-choline iodide as substrate.2.2. Optimum acetylcholine iodide hydrolysis occurred at pH 8·0 at 37°C in 0·05 M Tris-HCl buffer and pH 8·1 at 37°C in 0°1 M ammediol buffer for all species studied.3.3. The effect of sodium and potassium phosphate buffers and veronal-HCl buffer on enzyme activity was studied.4.4. Optimum substrate concentrations and Michaelis-Menten constants differed between species and sexes.

Changes in Dry Weight and Glycogen Content as Criteria for Measuring the Postcercarial Growth and Development of Schistosoma mansoni

Precise measurements of dry weight and glycogen content of individual worms were used as criteria in comparative studies of postcercarial growth of male and female Schistosoma mansoni. The growth rate and weight at maturity of males exceeded that of females, but only in the males did these 2 parameters show significant differences that could be related to the number of cercariae used to infect the host. Enzymic analyses of glycogen in worms during their postcercarial growth and development indicated that the ratios of glycogen content to dry weight change with time and that some dependent relationship may exist between the carbohydrate metabolism of male and female worms in copula.

Characterization of cell types in the parenchyma of Schistosoma mansoni.

SUMMARYA study has been made of the parenchyma of adult male Schistosoma mansoni by electron microscopy. Four different cell types have been characterized: one corresponding to cell bodies of the integument, two to muscle cells and another one to nerve cells with a possible neurosecretory function. The cytoplasm of the integument cell bodies is characterized by rod-shaped and round membrane-bound cytoplasmic bodies with a dense core, measuring 1200 to 2000 Å, similar to those found in the integument. One type of muscle cell has a large, clear nucleus, characteristic cytoplasmic vacuoles measuring up to 1 μm with a finely granular content and numerous free ribosomes. The other type of muscle cell is much smaller, with clumped nuclear chromatin and scanty perinuclear cytoplasm. Both types of cells give rise to muscle fibres which are morphologically distinct from the perinuclear cytoplasm. The nerve cells contain electron-dense, membrane-bound vesicles-ranging in size from 1000 to 3000 Å, similar to those found in nerve axons.Appreciable extracellular matrix has only been found under the integument and surrounding the processes of the integument cell bodies. This observation and the fact that silver methenamine after periodic oxidation stains intensely both the extracellular substance and the rod-shaped and round cytoplasmic bodies of the integument cells, suggests that these integument cells may be involve the production of extracellular matrix.This investigation was supported by grant AI 07806 from the U.S.P.H.S.The technical assistance of Mrs Lucille Jeffries and the photographic assistance of Mr William Douglas are acknowledged. This investigation was supported by the United States–Japan Cooperative Medical Science Program administered by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, Department of Health, Education and Welfare.

Lipid fractions in adult Schistosoma mansoni.

Total lipid from adult male and adult paired Schistosoma mansoni has been fractionated by thin-layer chromatography. Phospholipid, free sterol, and triglyceride were major components of both mixtures. A remarkably small amount of sterol ester was found in adult flukes considering the prevalence of this compound in mouse blood. Free fatty acids were found to be a minor component. Cholesterol was the major free sterol present.The technical assistance of Mrs Katye Ross Summerlin is gratefully acknowledged.

The Integument of Schistosoma Mansoni *

Abstract The structure of the integument of Schistosoma mansoni is described by histochemical and electron-microscopical study, and the effects of incubating adult schistosomes in buffered saline, thyoglycollic acid, horse-radish peroxidase, normal and immune serum are described. Stage-and-sex-determined structural variations between cercariae, schistosomules, and male and female adult schistosomes are discussed. As in other trematodes, the schistosome integument consists of an enveloping, syncytial epithelium connected to subjacent cytons by internuncial processes; a similar arrangement is found in schistosome muscle cells. In cercariae, the epithelium is covered by a finely fibrillar envelope; the other stages lack any noncellular envelope or cuticle. Tubular infoldings of the trilaminate outer plasma membrane are common in all three forms and grow increasingly complex with maturation. The male plasma membrane of the gynecophoric canal is thicker than the dorsal and is pentalaminate. The cell organelles associated with protein synthesis, e.g., polysomes, and Golgi apparatus are found in the cytons, whereas the superficial syncytium shows mitochondria, multilaminate vesicles, discoid granules, spines, and dense bodies—structures presumably associated with absorptive and protective functions; thus, there is evidence of morphologic polarization. In the male dorsal integument, but not in the ventral or female integument, horse-radish peroxidase is taken up during incubation, suggesting phagocytic activity and resorption of superficial plasma membranes by multilaminate vesicles. The fine structure of the spines is paracrystalline, suggesting tightly packed, repeating macromolecular subunits. Spines are closely associated with discoid granules, but the functions of both remain unknown. The dorsal tubercles of the adult male represent herniations of medullary parenchyma through gaps in the cortical-muscle layer. Ciliated globular termini of processes of medullary cells appear in the integumental epithelium and seem to be sensory neural endings. This study is preliminary to further investigations concerning interactions at the host-parasite interface, with particular reference to the relative indifference of living schistosomes to host antibodies and cellular defense mechanisms.

Studies in proline metabolism by Schistosoma mansoni—I. Radioautography following in vitro exposure to radioproline C 14

1. 1. When exposed in vitro to C 14 proline male schistosoma become much more heavily than do females. 2. 2. The areas of concentration in the male are the integument and sub-integument, the paraoesophageal region, the gut and the testes. 3. 3. In the female local accumulation in the posterior ovary and, to a lesser extent, in the mehlis gland was noted. 4. 4. The vitelline gland and duct fail to tag heavily on exposure; the female gut also shows minimal proline uptake. 5. 5. Proline may play a special metabolic role in either the paraoesophageal musculature or in the nearby neural ganglionic ring. 6. 6. Speculations concerning functional implications of these findings are given.

Anemia in Mice Infected with Gamma-Irradiated or Nonirradiated Schistosoma Mansoni

Summary Mice infected with nonirradiated schistosomes of both sexes demonstrated decreased hemoglobin and hematocrit values by 8 weeks after exposure. This apparent anemia was very severe by 12 weeks after exposure and was characterized by a depressed mean corpuscular hemoglobin concentration. Mice harboring a greater number of schistosomes of only the male sex demonstrated only a slight anemia by 16 weeks after exposure. Similarly, mice infected with both sexes of schistosomes, which had been irradiated with 3000 r so that oviposition was greatly diminished, demonstrated only slight anemia after 16 weeks of infection. However, no difference was detected between this partially sterile bisexual infection and the numerically equivalent infection of only male schistosomes. It is believed that the difference in accumulation of eggs in the tissues was of primary importance in producing the striking difference in response to the infection, and the mere presence of male and female schistosomes together in mice is no more pathogenic, as far as the production of the anemia of schistosomiasis is concerned, than is a numerically equivalent male schistosome infection.

Biochemical and morphological characteristics of subcellular fractions of male Schistosoma mansoni

A method is described for the subcellular fractionation of adult male Schistosoma mansoni, by differential centrifugation of homogenates in 0.3 M sucrose. Five fractions ( P1, P2, P3, P4, and S) were obtained, and each has been characterized morphologically and biochemically. Fraction P1 was the sediment obtained by spinning at 300 g av for 5 minutes; it was the most heterogeneous of the fractions, since it contained relatively large pieces of unbroken worm tissue and fragments of cuticle. Fraction P2, obtained by spinning at 1000 g av for 10 minutes, contained most of the free nuclei of the homogenate and was rich in DNA. Fraction P3, obtained after spinning at 8000 g av for 10 minutes, contained the mitochondria, muscle fibers, membrane fragments, and pigment; succinoxidase and alkaline phosphatase were concentrated in this fraction. A microsomal fraction, P4, was sedimented at 105,000 g av for 1 hour; it was rich in RNA and phospholipid and contained a high concentration of glucose-6-phosphatase. The final supernatant, S, contained 38% of the total protein of the homogenate, and was rich in acid phosphatase, alkaline phosphatase, and glucose-6-phosphatase.

THE EFFECTS OF ANTIMONY UPTAKE ON THE LOCATION AND PAIRING OF SCHISTOSOMA MANSONI.

The rate of uptake and elimination of antimony by both male and female schistosomes has been measured. It has been confirmed that the female schistosome is more susceptible to antimony therapy than the male since she absorbs more drug. The changes in location of the worms and the separation of the sexes following one or more injections of antimony potassium tartrate have been related to the different rates of uptake and elimination of the drug by the two sexes. The suppressive treatment of schistosomiasis is discussed in the light of these observations.

A cholinergic mechanism of inhibitory synaptic transmission in a molluscan nervous system.

A cholinergic mechanism of inhibitory synaptic transmission in a molluscan nervous system.

Susceptibility studies in schistosomiasis. III. Infection of various experimental hosts with Schistosoma haematobium in Egypt

Exposure of 472 animals to the cercariae of S. haematobium under conditions conducive to infection, and subsequent examination of these hosts has allowed an evaluation of the susceptibility of commonly used laboratory animals to infection by this parasite. 1. 1. All albino mice and hamsters exposed to cercariae became infected. Both are considered as usable laboratory hosts for experimental schistosomiasis with S. haematobium, although they display rather broad ranges in their susceptibilities. The former produces greater numbers of larger parasites but the latter may be the best all-around host, since the schistosomes reach the veins in the vicinity of the urinary bladder as well as those in the lower levels of the large intestine. Mice and hamsters could probably be used more effectively if exposed to larger numbers of parasites than employed in this study. 2. 2. Albino rats, cotton rats and guinea pigs are poor hosts for S. haematobium. The numbers of parasites are drastically reduced in early stages of infection in albino rats and guinea pigs. Rabbits and dogs are refractory to infection and cats produce almost negligible numbers of subnormal parasites although exposed to large numbers of cercariae. Goats can be infected but the return of schistosomes is extremely low. 3. 3. Monkeys and baboons are good hosts for experimental studies. However it must be realized that these primates as well as acceptable rodents demonstrate variable degrees of susceptibility or tolerance for S. haematobium. The parasite may or may not reach the vessels of the urogenital system which is supposedly a natural definitive location for S. haematobium in man. 4. 4. There is a slight predominance of male schistosomes if the overall return of parasites is considered. Only male schistosomes were recovered from guinea pigs. Female schistosomes were slightly in the majority when sex determinations were made using cercariae from naturally infected snails. 5. 5. Pathologically, the primates stand alone in demonstrating conditions of involvement comparable to those found in man. Pathologic changes in monkeys and baboons were inconsistent, the urinary bladder being involved in some individuals but not in others. In mice a few eggs were found in the tissues near the urinary bladder but no parasites were demonstrated. In hamsters there were both worms and eggs in the region of the urinary bladder, with some tissue damage. Albino rats and guinea pigs showed little tissue damage since eggs were deposited in neither the intestine nor the bladder. Cotton rats demonstrated only minor lesions since the parasites were few and only a limited quantity of eggs was found in the walls of the large intestine. A majority of albino mice and hamsters, and a few cotton rats possessed eggs in the liver. In this respect pathologic involvement was not remarkable. Eggs were not found in the livers of white rats and guinea pigs. 6. 6. Splenomegaly occurred in many of the mice infected with S. haematobium but only in two hamsters. There was no indication of splenic enlargement in albino rats, cotton rats or guinea pigs. The occurrence and the degree of splenomegaly in the primates was surprisingly low. There is no consistent relationship between parasite returns and splenic enlargement although this condition appeared more frequently in mice with prolonged periods of infection. 7. 7. Egg production and subsequent passage with the feces and urine were variable and seemed to depend mostly on individual compatibility or host-parasite relationship. Only moderate quantities of eggs were passed irregularly by mice and hamsters. The peak in egg passage with feces was reached at 16 to 24 weeks. Quantities of eggs were regularly recovered from feces after this period in some cases but in others egg passage ceased entirely. Cotton rats passed only limited numbers of viable eggs, whereas albino rats and guinea pigs passed none. Monkeys and baboons passed moderate quantities of eggs with the feces and on a few occasions in the urine. Their recovery from the primates was just as erratic as that recorded for rodents and when estimated on a per worm basis, the quantity of eggs produced is of the same magnitude.