Himasthla Quissetensis Research Articles

Changes in concentrations of free amino acids in larval stages of the trematode, Himasthla quissetensis and its intermediate host, Nassarius obsoletus

1.1. The first intermediate host, Nassarius obsoletus, reacted to salinity changes in a similar fashion whether parasitized or nonparasitized.2.2. The primary amino acids involved with salinity stress in the host were taurine, glutarnic acid, aspartic acid, and proline.3.3. The major amino acid functioning as an osmotic effector in the rediae and cercariae of Himasthla quissetensis was proline.4.4. The proline concentration apparently drops to one half of its original value as the trematode develops from the redial to the cercarial stage in its complex life cycle.

Himasthla quissetensis: Induced in vitro encystment of cercaria and ultrastructure of the cyst

Himasthla quissetensis cercariae were induced to encyst in solutions of casein hydrolysate, sodium glutamate, lysine, arginine, glucose, α-methylglucoside, 3-0-methylglucose, glucosamine, gluconate, galactose, xylose, cellobiose, maltose, clam mucus, and diffusates from bluegill and eel skin. The approximately ellipsoidal cyst is composed of an outer homogeneous layer formed by granules released from the tegument and an inner laminated layer formed by scrolled rods originating in subtegumental cell bodies. Encysted metacercariae were infective to fledgling seagulls. Cercariae of Leopcreadium setiferoides, Cryptocotyle lingua, and Parorchis acanthus could not be induced to encyst in vitro by addition of casein hydrolysate.

Fatty acid compositions of three lipid classes of Himasthla quissetensis rediae before and after starvation

1.1. The major neutral lipid classes of Himasthla quissetensis rediae are sterols, free fatty acids, triglycerides and sterol esters.2.2. Sixteen fatty acid components of these classes have been resolved using gas-liquid chromatography. The major fatty acid in the sterol ester class is C20:1, in the triglyceride class is C18:1 and in the free fatty acid class is C16:0.3.3. The fatty acid composition of the triglyceride class varies while the composition of the free fatty acid fraction shows a decrease in the relative proportions of C18:1 and shorte chain fatty acids following in vitro starvation. The relative fatty acid composition of the sterol ester class shows no change after starvation.

Himasthla quissetensis: Uptake and utilization of glucose by rediae as determined by autoradiography and respirometry

Daughter rediae of Himasthla quissetensis removed from the digestive gland of Nassarius obsoletus were placed in sterilized seawater fortified with antibiotics. When [ 3H]-glucose was added to this medium and autoradiographs were made after 3, 9, and 24 hr of exposure, labeling was observed associated with the redial walls and developing germ balls and cercariae within the brood chambers. Respirometric determinations on starved rediae suspended in the seawater medium with and without glucose revealed the rate of oxygen utilization by rediae exposed to exogenous glucose is significantly elevated. These results are interpreted to mean that the daughter rediae of H. quissetensis can take up and utilize glucose.

Dehydrogenase activity in the rediae of Himasthla quissetensis (Trematoda) as an indicator of substrate utilization

1. 1. The levels of dehydrogenase activity in specimens of daugther redise of Himasthla quissetensis removed from the digestive gland of Nassarius obsoletus were determined by employing the methylene blue reduction method. These measurements were made on rediae suspended in a sterile, sea-water medium or in media in which sodium succinate, glucose or trehalose had been added. 2. 2. The presence of sodium soccinate, glucose or trehalose increases the level of dehydrogenase activity and it is concluded that these substrates are utilized by the rediae. 3. 3. The data indicating an increase in dehydrogenase activity, coupled with our earlier report of increased oxygen consumption in similar rediae when exposed to glucose (Hoskin & Cheng, 1973), suggest that, contrary to an earlier report, H. quissetensis rediae do metabolize glucose.

Fatty acid composition of parasitized and nonparasitized tissue of the mud-flat snail, Nassarius obsolete (Say)

Fatty acid composition was analyzed in nonparasitized digestive gland tissue of Nassarius obsoleta and in digestive gland tissue of this host parasitized with one of four species of larval trematodes: Zoogonus lasius, Lepocreadium setiferoides, Austrobilharzia variglandis, and Himasthla quissetensis. The larval trematodes differentially affected the fatty acid composition of the tissue of their molluscan host.

Fine Structure of the Cuticle of the Cercaria of Acanthatrium oregonense (Macy)

The integument of the cercaria of Acanthatrium oreganense was studied by means of electron microscopy and histochemistry. The ultrastructure of the cuticle varies in different regions of the body. The body cuticle is characterized by the presence of fibril-containing vesicles in the syncytial cytoplasmic layer. These vesicles occur in the sucker in great density, but are absent from the tail cuticle. Instead there are small elongate cavities along the periphery of the tail cuticle. These structural differences have been correlated with histochemical findings. Chemically the body cuticle and sucker may be differentiated from the tail cuticle by the presence of mucopolysaccharides. The subcuticular layer of the body has a concentration of glycogen. Only a few workers have investigated the ultrastructure of trematode larval stages. Kruidenier and Vatter (1960) studied the cercaria of Schistosoma mansoni, limiting their discussion to the musculature of the tail. The cercaria of Himasthla quissetensis was studied with some reference to the integument (Cardell and Philpott, 1960; Cardell, 1962). The only work to focus specifically on the integument of cercariae is a study of the histogenesis of trematode cuticle from the sporocyst stage to the adult trematode, made by means of the electron microscope (Bils and Martin, 1966). Their discussion of one strigeid and three echinostome cercariae did not include descriptions of the tail and sucker. A more recent paper by Rees (1966) in this area briefly describes the ultrastructure of the integument of the redia of Parorchis acanthus. Axmann (1947) did the first studies localizing glycogen deposits in various larval stages and in the adults of three schistosomes. Her work has been continued in investigations of the histochemistry of larval trematodes and their effects on the pathology of the molluscan intermediate hosts (Cheng, 1963a, b; Cheng and Snyder, 1962, 1963). The purpose of this investigation was to provide more detailed information about the structure of the cercaria. Such an investigation would provide valuable information about the host-parasite relationship. MATERIALS AND METHODS Naturally infected snails, Oxytrema siliqua (Gould), were collected from Oak Creek near Received for publication 28 November 1966. * Present address: Department of Biology, California State College at Hayward. Corvallis, Oregon. Emerged cercariae were fixed in preparation for ultrastructural and histochemical study.

Effects of plasma and tissue extracts of marine pelecypods on the cercaria of Himasthla quissetensis

Himasthla quissetensis cercariae, freshly emitted from Nassarius obsoletus, were exposed to the plasma and tissue extracts of 7 species of marine pelecypods, Mercenaria mercenaria, Mya arenaria, Crassostrea gigas, C. virginica, Tapes philippinarium, Mytilus edulis, and Modiolus demissus. The plasma of all the molluscan species stimulated cercarial encystment, but the rapidity of encystation varied with the types of sera. The stimulatory component of the sera was heat labile. All of the tissue extracts caused the death of cercariae, with the time of death again varying with the type of extract; however, the longevity of the cercariae was definitely much less than those maintained in seawater. The absence of metacercariae in the tissues of C. gigas and C. virginica is believed to be due to the immobilization of penetrating cercariae by plasma seeping into the mantle cavity.

A Comparative Study of the Susceptibility and Response of Eight Species of Marine Pelecypods to the Trematode Himasthla quissetensis

Specimens of eight species of marine pelecypods, Crassostrea virginica, C. gigas, Mytilus edulis, Modiolus demissus, Ensis directus, Mya arenaria, Mercenaria mercenaria, and Tapes philippinarum, were individually challenged with 150 Himasthla quissetensis cercariae in order to study their susceptibility and reactions. Quantitative recovery rates are given. Metacercariae were found encysted in various tissues of all of the pelecypods except C. virginica and C. gigas. In C. virginica few metacercariae were found in blood vessel lumina. Except in T. philippinarum, when metacercariae were found in tissues, they were enveloped by a non-cellular, parasite-secreted inner cyst wall. In T. philippinarum, only those metacercariae found in the testes were enveloped by such a wall. In addition to the inner wall, an outer wall, comprised of host leucocytes and either myofibers or connective tissue fibers, surrounded encysted metacercariae in most instances. The fibrous constituent of the outer wall appeared to be dependent on the type of fibers available in the immediate proximity, while the leucocytes are believed to be attracted by the inner wall. Encysted metacercariae were found on the gill and mantle surfaces of C. virginica and C. gigas and on the palps of M. edulis. These are believed to be inactivated, and thus prevented from invading the molluscs, by some host-elaborated substance. Adults of the echinostomatid trematode Himasthla quissetensis (Miller and Northrup) were originally described by Stunkard (1937) from gulls, Larus argentatus Pontoppidan, which were experimentally infected with metacercariae in molluscs which had been exposed to Cercaria quissetensis Miller & Northrup, 1926, a larval trematode of the mud snail, Nassarius obsoletus Say, collected at Woods Hole, Massachusetts. In one abstract (Stunkard, 1934) and two papers (Stunkard, 1937, 1938), Stunkard reported the life cycle of this parasite. In these papers he recorded that seven species of marine molluscs, Mya arenaria L., Modiolus modiolus L., Mytilus edulis L., Cumingia tellinoides Conrad, Aequipecten irradians L., Ensis directus Conrad, and Crepidula fornicata L., were compatible second intermediate hosts into which the cercariae penetrated and encysted. He reported encystment in the mantle, gills, and foot of these molluscs. Uzmann (1951) reported that the soft clam, Mya arenaria, is an important second intermediate host of H. quissetensis in nature since he found 43 to 100% of the samples of this clam from Merrimac Bay, Plum Island Sound, and Annisquam River, Massachusetts, and 90% of 50 specimens of this clam from St. Andrews, New Brunswick, Canada, to harbor metacercariae of this trematode. During a recent survey of the parasites of Nassarius obsoletus in Narragansett

Interrelationships between parasites and their hosts—I. Comparative metabolic patterns of thermal acclimation of larval trematodes with that of their host

1. 1. Patterns of metabolic adaptation in thermal acclimation have been determined for the common mud-flat snail, Nassarius obsoleta, and two species of larval trematodes, Zoögonus rubellus and Himasthla quissetensis. Both of these species of larval trematodes utilize N. obsoleta as the first intermediate host. 2. 2. Although the host and its parasites are subject to the same general thermal environment, all three species exhibit distinctively different patterns of acclimation. 3. 3. It would appear that the thermal environment of the intermediate host has little or no influence on the physiology of thermal acclimation in the trematode larvae.

Utilization of certain substrates by larval and adult stages of Himasthla quissetensis

Proline and glutamic acid increased the respiration rate of rediae of H. quissetensis, but glucose, fucose, mannose, and ribose were without effect. Succinate also caused increased oxygen uptake, and manolate sharply decreased the q O 2 . Glucose, proline, succinate, and malonate were without effect on the respiration rate of both whole cercariae and homogenates. Adult H. quissetensis showed greatest increases in respiration rate with glucose, mannose, and succinate; proline was only slightly effective in increasing the respiration rate.

Studies on oxygen consumption in digenetic trematodes. VI. The influence of temperature on larval trematodes

1. 1. The metabolic response of two species of larval trematodes has been determined at temperatures varying from 6–41 ° C. 2. 2. The two species of trematodes used are Himasthla quissetensis, found in sea gulls in the adult stage, and Zoögonus rubellus, which utilizes marine fish as the definitive host. The larval stages of both species are found in the mud-flat snail, Nassarius obsoleta. 3. 3. The larvae of the fish parasite die within a half hour at 39 ° C, while the larvae of the bird parasite were still alive and active at the end of a six hour period at 41 ° C. 4. 4. The Q 10 values of the larvae of H. quissetensis tended to reflect the temperature of the definitive host.