Ultrastructural localization of phosphoglycerate kinase in adult Clonorchis sinensis

Phosphoglycerate kinase (PGK) is an enzyme that produces one ATP molecule in the glycolytic pathway. Clonorchis sinensis is largely dependent on glycolysis for energy production. We performed immunoelectron microscopy on adult C. sinensis by using mouse immune serum raised against recombinant C. sinensis PGK. A high density of gold particles was found in the microvilli of the intestinal epithelium and in lamellae of the sperm duct. PGK was common in the somatic cells of intra-uterine eggs and in excreted products. It was localized with moderate intensity in muscular fibers of the subtegumental muscle layer, and in the myoepithelia of the intestine and excretory bladder. We suggest that PGK plays an essential role in C. sinensis energy production for movement via muscle contraction.

Clonorchis sinensis: immunolocalization of 26 kDa glutathione S-transferase in adult worms

A mu-class glutathione S-transferase (Cs26GST) of molecular mass 26 kDa was characterized from Clonorchis sinensis. In adult C. sinensis, the distribution of the Cs26GST was investigated by immuno-histochemistry and electron microscopy. Cs26GST was localized to the tegument and parenchyma. Immunogold labeling was strong in the tegumental cell bodies and moderate in the tegument and ova in the oviduct. It is suggested that Cs26GST plays a role in the metabolism and fecundity of C. sinensis.

Purification and characterization of a 7-kDa protein from Clonorchis sinensis adult worms

A 7-kDa protein was purified from extracts of adult Clonorchis sinensis by a combination of ammonium sulfate precipitation, anion exchange chromatography, cation exchange chromatography, gel-filtration chromatography, and reversed-phase FPLC. The 7-kDa protein exists in the excretory-secretory products of adult C. sinensis, but not in extracts of adult Paragonimus westermani. Also, the 7-kDa protein reacted with the sera of patients with clonorchiasis but not with paragonimiasis or normal human sera. To observe the localization of the 7-kDa protein in the tissue of adult C. sinensis, an immunogold labeling method was followed using anti-7-kDa antibody. The gold particles were observed in the basal layer below the tegumental syncytium, in the interstitial matrix of the parenchyma, and in the content of the uterus. The 7-kDa cDNA was obtained through reverse transcription-polymerase chain reaction using a primer designed from N-terminal sequence analysis. Rapid amplification of cDNA ends (5'-RACE) was used to obtain the complete protein coding sequence. The sequence encodes a 90-amino acid polypeptide. The deduced amino acid sequence of the 7-kDa protein revealed no homology with proteins of different organisms reported so far. These results suggest that the 7-kDa protein is a fluid antigen and may be valuable as a tool for the immunodiagnosis of clonorchiasis.

Image analytical observation on the growth and development of Clonorchis sinensis in rats

For the two-dimensional observation on the growth and development of Clonorchis sinensis, an image analysis system (IBAS 2000, Kontron, Germany) was used in this study. On 3, 6, 9, 12, 15, 21, 30 and 90 days of infection, 474 worms were collected from rats infected with 50 metacercariae each. The overall recovery rate was 31.6%. The worms grew rapidly in their length and width up to 30 days of infection and then, did slowly to 90 days of infection. However, the growth pattern of body area was not similar to that of body length and width, because the body area increased continuously even after 30 days of infection. With the image analysis system, the sizes of irregular-shaped genital organs were measured easily, which showed sigmoidal growth patterns. The growth rate of genital organs increased rapidly until 21 days of infection when the uterus was filled with numerous eggs, and then gradually slowed down to 90 days. There was no difference in growth pattern between the anterior and posterior testis. The seminal receptacle, however, showed an abrupt increase in size between 15 to 21 days of infection when it was filled with condensed semen. Therefore, the growth pattern of seminal receptacle might be used as another criteria to estimate the extent of sexual maturation of C. sinensis. From this study, it is suggested that image analysis system is very useful to reveal the growth and development pattern of C. sinensis, especially of their internal organs.

[The functional characteristics of the ultrastructure of the outer membranes of opisthorchid eggs. 2. The mechanisms of egg retention on substrates]

The studies of the functional features of the ultrastructure of the outer membranes of Opisthorchis felineus and Clonorchis sinensis eggs have been continued. The variants of egg behavior on different substrates (artificial, natural, organic and inorganic) have been experimentally studied. It has been established that O. felineus and C. sinensis eggs retain on a number of substrates due to covering with microflora (e.g. fungus mycelium clinging to the rubbed surface of the egg outer membranes); sticking in the uneven surface of the substrate; catching in the uneven surface of the substrate; catching on microfibers of plant fragments. The features found are to a great extent caused by a complex comb-like structure of egg membranes and are interpreted in terms of the earlier unknown mechanisms of parasite adaptation (at the egg stage) facilitating its contact with molluscs--their intermediate hosts.

[The morphofunctional characteristics of the ultrastructure of the outer membrane of opisthorchid eggs. 1. The hatching of miracidia]

Some functional peculiarities of miracidia hatching from O. felineus eggs have been studied, using scanning electron microscope. The results were compared to the earlier data obtained by the method elaborated for the determination of opisthorchis eggs viability by stimulation of miracidia release in the artificial media. It is concluded that in the course of miracidia hatching the two release-stimulating factors (mechanical and chemical) are mutually complementing each other. First, the egg membrane is deformed, in which the radula of the mollusk host plays an essential role, then the process of chemical activation of the hatching gland is triggered and miracidia motor activity is stimulated. A complex comb-shaped structure of opisthorchis eggs outer membranes is associated with the necessity of long-term eggs survival in the water reservoirs and forms a light delicate carcass preventing the egg from deformation.

Clonorchiasis in Korea

Since the first report on the incidence of egg positiveness of Clonorchis sinensis by Matsumoto in 1915, clonorchiasis has been recognized as one of the most important endemic diseases in Korea. Most of the works on clonorchiasis after then had been studied by Japanese workers until 1945. After the Korean War in 1950-1953, health problems of Koreans were extremely aggravated. This gave us attentions for the prevention of contagious diseases as well as parasitic infections in public health point of view. It was greatly recognized that not only ascariasis, hookworm infections, and trichuriasis, but also clonorchiasis and paragonimiasis constitute the important helminthic diseases in Korea. In the late 1950s, several Korean workers conducted studies of C. sinensis on its biology, epidemiology, pathology, clinical symptoms as well as treatment. Thereafter overall epidemiological surveys were carried out actively throughout the country since 1960s. From these surveys, it became clear that endemic areas of clonorchiasis are scattered all over the country along the Nakdong, Kum, Mankyong, Yeongsan and Han rivers. The most extensive and intensive endemic regions were found mainly along the Nakdong river. Since then, clonorchiasis has been one of the most extensively studied subjects during the past 30 years. The present review mainly deals with current results obtained by Korean investigators on the prevalence of clonorchiasis, as well as its biology, epidemiology, pathogenesis, clinical manifestations, diagnosis, treatment, prevention and control.

[The differentiation of Opisthorchis eggs by the ultrastructure of their outer membranes]

Using a TESLA-BS-300 scanning electron microscope, the ultrastructure of the outer membranes of oocysts of 8 opisthorchis species (Opisthorchis felineus, O. viverrini, O. geminus, Clonorchis sinesis, Amphimerus anatis, Metorchis albidus, Pseudamphistomum truncatum, Erchoviorchis lintoni) belonging to 4 subfamilies, as well as that of O. felineus oocysts of various geographical isolates (from the Ukraine, the Volga region, West Siberia, Kazakhstan) have been investigated. The nature of the ultrastructure of the membranes differs from species to species and can be used for the differentiation of opisthorchis oocysts. Marked differences have been observed in different opisthorchis subfamilies (Opisthorchinae, Metorchinae, Pseudamphistominae, Pseudamphimerinae). The membrane ultrastructure was not significantly different in O. felineus oocysts from various geographical isolates, however, there are some distinctions in the size of oocysts and the form of apical thorns and opercular endings. The work has been done within the framework of the international scientific cooperation between the E. I. Martsinovskiĭ Institute of Medical Parasitology and Tropical Medicine, USSR Ministry of Public Health and the Institute of Parasitology, the Czechoslovakian Academy of Sciences.

Structural investigation on the effects of the herbs on Clonorchis sinensis in rabbits

The effects of boiled water extracts of clonorchicidal raw drugs screened by the EPG counts in vivo on the structure of Clonorchis sinensis were investigated. The extracts of Cassia obutusifolia and Dictamnus dasycarpus did not seem to induce the morphological changes of the worms, and in those of Machilus thunbergii and Prunús mume, widening of bladder to lower level of seminal receptacle was visible without any other changes. Those of Inula helenium and Saussurea lappa, however, disclosed regressive and progressive changes as degeneration, atrophy, necrosis, dilatation, etc. of viscera of the worms. The recover rates of the worms from experimentally infected rabbits administered with the extracts of I. helenium and S. lappa for 30 days, beginning at the 3rd day of inoculation, were as low as 2% and 2.8%, respectively.

The ultrastructural characterization of the tegument of Clonorchis sinensis (Cobbold, 1875) cercaria

The tegumental ultrastructure of the cercaria of the liver fluke, Clonorchis sinensis (Cobbold, 1875), was studied by scanning and transmission electron microscopy. The body surface is almost encircled by many rows of regularly arranged spines. The tegumental syncytium of the body contains many rod-shaped dense granules and central electron-lucent bodies, neither of which are present in the tail tegument. There are four rows of hooked teeth and modified spines on the oral cone. These teeth are differentiated morphologically and probably functionally from the other body spines. Disc-shaped papillae with long or short cilia are distributed on the body in a bilaterally symmetrical pattern dorsally and ventrally. There are 30 to 37 papillae with much longer cilia laterally. Four pairs of papillae were found on the tail. From their structure and location these papillae appear to have a mainly tango- or rheoreceptive function. Another type of sheathed papillae is situated around the oral sucker. The cuticular tegument is expanded laterally at the base of the tail, forming a characteristic sac-like structure.

Surface ultrastructure of the tegument of Clonorchis sinensis newly excysted juveniles and adult worms

The tegumental structures of newly excysted juveniles and adult worms of Clonorchis sinensis were studied using scanning and transmission electron microscopy. After excystation the juvenile's tegumental surface is characterized by knoblike protuberances and is armed almost entirely with numerous rows of small spines encircling the body. These spines are double- or triple-pointed on the anterior portion of the body and become single-pointed posteriorly. Four types of presumed sensory structures were observed as follow: A) ciliated knoblike papillae and B) nonciliated platelike papillae, both of which are arranged in rougly a bilaterally symmetrical pattern dorsally, ventrally, and laterally; C) rounded swellings of nonciliated papillae on the lips of the ventral and oral suckers, which are characterized in the transmission electron microscope by a rounded dense body in the apical bulb; and D) a sensory receptor with a bulbous projection having the appearance of a modified cilium, which was not found with SEM likely owing to its being enclosed by an extension of the tegument. In full-grown adult worms, the tegumental surface is knobbed or lobulated in various forms without surface spines. The tegumental structures in the adults appear to be clearly differentiated from those in the juveniles. Upraised, buttonlike papillae, each topped by a short cilium, which are similar to the Type A papillae in the juveniles, are distributed thickly around the oral and ventral suckers, and are rather randomly scattered over the remainder of the body. Some nonciliated swollen papillae were found on the lip of the ventral sucker.