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PubMed1992

Ultrastructure and histochemistry of the lymph system and parenchyma of juvenile paramphistomes (Paramphistomidae: Digenea) during migration in Indian ruminants.

The lymph system of juvenile Paramphistomum epiclitum and Fischoederius elongatus consists of a single pair of longitudinal primary vessels from which sub-dividing branches extend laterally to associate with most major tissues and organs. The system originates shortly after excystation in the definitive host and is fully developed in day 14 juveniles. Lymph vessels are syncytial and membrane limited, with a matrix which contains autophagic-like inclusions, clusters of SER and free nuclei. Similar organelles are evident in the matrix of parenchyma and specialized cells juxta-posing the pharynx (JP cells). These tissues are intimately associated and perhaps functionally integrated. Parenchyma represents a major site for carbohydrate storage and turnover, whilst the lymph appears to perform a similar role for proteins. The JP cells of juveniles display prolific autophagic-like activity only during migration, which coincides with the depletion of carbohydrate reserves in parenchyma. Key mitochondrial enzymes were histochemically demonstrated in the lymph despite the apparent absence of mitochondria from this system in post-day 14 juveniles. Succinate dehydrogenase activity was cytolocalized in mitochondria, whilst attempts to perform a similar localization of this enzyme in lymph were unsuccessful. The possibility of non-enzymatic interference in the histochemical demonstration of dehydrogenase is examined.

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PubMed1992

A response to light in an adult encotyllabine (capsalid) monogenean from the pharyngeal tooth pads of some marine teleost fishes.

A response to light in an adult monogenean is reported for the first time. Living encotyllabine (capsalid) monogeneans, identified tentatively as Encotyllable caballeroi Velasquez, 1977, attached to pharyngeal tooth pads excised from two species of teleost fish, contracted rapidly when the intensity of the incident illumination was suddenly increased. Contracted individuals were immobile and largely concealed in crevices in the tooth pads. Parasites habituated to the higher light intensity after 60-100 s and re-extended their bodies and resumed activity. Contracted, immobile individuals re-extended prematurely if the light intensity was reduced during the habituation period. Detached parasites responded in the same way to abrupt changes in the illumination intensity. The possible significance of this response in relation to the biology of the hosts is briefly discussed.

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PubMed1992

Ultrastructure of the protonephridial system, of Anoplodiscus cirrusspiralis (Monogenea Monopisthocotylea).

The flame bulb is formed by a terminal cell and a proximal canal cell. The weir consists of interdigitating ribs all of which form one circle, i.e. alternating ribs do not have distinctly 'internal' or 'external' positions. Cytoplasmic cords are absent and all ribs, i.e. those continuous with the proximal canal cell and those continuous with the terminal cell, form external leptotriches. At least some external leptotriches have interconnected branches extending along the flame bulb. Internal leptotriches are not branched and arise from the basal perikaryon of the terminal cell. In the cytoplasmic cylinder at the tip of the flame bulb, structures resembling incomplete septate junctions were seen. However, neither the cytoplasmic cylinder nor the small protonephridial capillaries contain complete septate junctions as found in all other Monogenea Polyopisthocotylea, Monogenea Monopisthocotylea, Trematoda Aspidogastrea and Trematoda Digenea examined to date. In the lack of a septate junction, Anoplodiscus resembles Udonella, Amphilinidea, Gyrocotylidea and Eucestoda. However, the presence in this species of rudimentary septate junctions in the small capillaries and of complete junctions in larger ones indicates that complete junctions have been secondarily lost. Anoplodiscus resembles the Monogenea and Trematoda in the presence of lamellae in the larger protonephridial ducts. For the first time in a monogenean, the ultrastructure of the excretory bladder is described. A nucleated convoluted duct opens through a narrow connecting duct into the bladder, which in turn opens through a narrow connecting duct into the excretory pore lined by tegument. Convoluted duct, connecting ducts and bladder are lined by a lamellated epitheliu.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1993

The influence of formalin, benzocaine and hyposalinity on the fecundity and viability of Polylabroides multispinosus (Monogenea: Microcotylidae) parasitic on the gills of Acanthopagrus australis (Pisces: Sparidae).

Adult Polylabroides multispinosus exposed in vivo to formalin (200 p.p.m. in sea water, 30 min) deposited a similar number of eggs in 24 h in vitro as did control parasites (sea water, 35 parts per thousand, p.p.t., salinity) and worms exposed in vivo to benzocaine (40 p.p.m. in sea water, 10 min). Worms laid more eggs at 30 p.p.t. salinity in vitro than at 20, 35, 10 and 5 p.p.t. salinity (in decreasing order). Formalin (200 p.p.m., 30 min) decreased the viability of recently laid eggs, the survival of oncomiracidia, removed 70% of juvenile and adult worms from the gills, but decreased only slightly the viability of eggs exposed in utero or after eyespots developed in vitro. Salinities below 30 p.p.t. reduced viability as did an increase in temperature from 24 to 28 degrees C. All adult and juvenile worms were removed by baths in formalin (400 p.p.m., 25 min) or fresh water (1 h).

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PubMed1993

Insemination and population density in Entobdella soleae, a monogenean skin parasite of the common sole, Solea solea.

Immature specimens of the monogenean skin parasite Entobdella soleae, experimentally isolated from other individuals, fail to self-inseminate when maturity is reached and self-insemination has not been recognized during many hours spent observing living parasites. E. soleae lives on the lower surface of its flatfish host, the common sole (Solea solea), in relatively small numbers, most commonly 1, 2 or 3 adults per fish, but in spite of the low density and extensive habitat, freshly collected wild parasites were found to be inseminated. If it is assumed that E. soleae is unable to self-inseminate in the wild, then it seems likely that single isolated parasites on wild soles have lost their partners as a result of death or transfer to another host and that parasites have an efficient way of locating a mating partner. Mathematical modelling indicates that random locomotion with searching movements of the body would lead to mating contacts between 2 individuals on a small sole within the reproductive life-time of the parasites, but is unlikely to maximize reproductive output because it cannot ensure that mating will occur soon after sexual maturity is achieved. It is suggested that pheromonal attraction may ensure early meetings and that the thin stagnant layer of sea water between the lower surface of the relatively inactive sole and the sea bottom is an ideal environment for the operation of such a system and may account for the preference of adult E. soleae for the host's lower surface.

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PubMed1993

Fertilization and the functional anatomy of the germarium in the monogenean Entobdella soleae.

The germarium of the monogenean skin parasite Entobdella soleae encloses a coiled tube containing many mature oocytes. This intragermarial tube communicates distally with the oviduct. The proximal end of the tube is closed by a "plug cell" which is suspended by finger-like cytoplasmic processes attached to the sheaths enclosing dorso-ventral muscle fibres passing through the main compartment of the germarium. Mature oocytes reach the tube lumen by penetrating the plug cell cytoplasm and this may be achieved by amoeboid movement of the oocyte. The tube contains spermatozoa and fertilization begins soon after a mature oocyte enters the tube. The events of fertilization have been determined by sequential ultrastructural studies of oocytes in the tube.

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PubMed1993

A new species of Haliotrema (Monogenea: Ancyrocephalidae) from a Japanese puffer fish Takifugu niphobles (Tetraodontiformes: Tetraodontidae).

A new species of Haliotrema is described on the basis of material from the gills of the Japanese puffer fish Takifugu niphobles. The new species is compared to other ancyrocephalids from tetraodontid hosts and congeners with similar copulum morphology from unrelated hosts. It is distinguished from these species based on a combination of reproductive and haptoral characters. Comparison of the haptor musculature of the new species with that described for Haliotrema balisticus revealed a potential for additional taxonomic characters. Resolution of differences in the interpretation of the functional morphology of the muscle groups in the two species will require further investigation.

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PubMed1993

The ultrastructure of the tegument and clamp attachment organ of Gotocotyla bivaginalis (Monogenea, Polyopisthocotylea).

The tegument of Gotocotyla bivaginalis consists of a syncytium, perikarya and four kinds of secretory bodies, viz. electron-dense granules, moderately electron-dense vesicles, electron-lucent vesicles and large multivesicular bodies occurring in the ratio of 83:50:40:1. Microvillus-like structures, finger-like projections and a thin coat of glycocalyx occur on the In contrast, the syncytium of the clamp is relatively thin and irregularly folded, containing only three kinds of secretory bodies, viz. electron-dense granules, a few moderately electron-dense granules and several large electron-lucent vacuole-like structures in the ratio of 15:2:5. Exocytosis of the electron-dense and -lucent vesicles is apparently prevalent both in the syncytium of the haptor and general body surface. Tegumental damages induced by natural mechanical forces appear to occur in some regions of the syncytium of the clamps/haptor. Sclerites of the clamp are electron-dense and they are interconnected by the basal lamina, tendon and radial muscle fibres. Interstitial space is absent between the sarcolemma of adjacent muscle fibres of the clamp. Groups of neurons and non-myelinated nervous processes can be seen in the vicinity of the clamps. The axon is subdivided by invaginations of the neurolemma. Presumed non-ciliated mechano-receptors occur on the body surface.

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PubMed1993

A survey of didymozoid trematodes of the barracuda Sphyraena obtusata from Kuwait Bay.

Examination of 120 yellow-finned barracudas, Sphyraena obtusata, from Kuwait Bay revealed 8 species of didymozoid trematodes encapsulated in pairs in the tissues. Four species of the didymozoids, Allodidymozoon operculare, Didymocylindrus sp., Didymocystis sp., and Didymocystoides sp., were found in the head region, 3 species, Didymozoon tetragynae, Lepidodidymozoon sinicum and Platocystoides polyaster, in external surfaces and 1 species, Allodidymozoon sp., in stomach wall. The didymozoid species collected constitute new geographic distribution records and occurrence of D. tetragynae and L. sinicum are new host records.

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PubMed1995

Use of cement for attachment in Neocalceostomoides brisbanensis, a calceostomatine monogenean from the gill chamber of the blue catfish, Arius graeffei.

The thin, weakly muscular, disc-shaped haptor of the calceostomatine monogenean Neocalceostomoides brisbanensis is attached to surfaces in the gill chamber of its catfish host by cement. It is unlikely that any suction is generated (there are no muscular loculi) and the hooks are reduced in size. Two distinctive secretions are associated with the haptor: a finely granular secretion from glandular tissue within the haptor and anterior to it, which enters the dorsal haptor tegument near the periphery of the disc and spreads throughout the ventral haptor tegument; a coarser secretion produced in the peduncle and posterior region of the body, which finds its way to gland openings near the hamuli via centrally situated large and small haptor reservoirs. It seems most likely that the tegumentary secretion is the cement, but other possibilities are discussed. It is suggested that the increasing importance of cement for haptor attachment in calceostomatines has led to the development of a weakly muscular, foliaceous haptor and a progressive reduction of the hooks.

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PubMed1994

Ancyrocephaline monogeneans of the genera Chauhanellus and Hamatopeduncularia from the gills of the blue catfish, Arius graeffei, in the Brisbane River and Moreton Bay, Queensland, Australia, with descriptions of four new species.

At least six ancyrocephaline monogeneans, four of which are new species, are reported from the gills of the blue catfish, Arius graeffei, in the Brisbane area, Queensland, Australia, namely Chauhanellus australis (Young, 1967) Bychowsky & Nagibina, 1969, Chauhanellus youngi new species, Hamatopeduncularia pearsoni new species, Hamatopeduncularia brisbanensis Young, 1967, Hamatopeduncularia major new species and Hamatopeduncularia spiralis new species. H. major has been found so far only on catfishes from the Brisbane River (freshwater) and C. youngi and H. brisbanensis only on catfishes from Moreton Bay (salt water). H. spiralis is described from river catfishes; a similar, possibly identical parasite occurs on bay catfishes. Young's paratypes of H. brisbanensis were found to include specimens of H. pearsoni new species. Additional observations were made on the anatomy and biology of C. australis and H. brisbanensis, with special attention being paid to the haptor glands. New light is shed on the function of the marginal-hooklet-bearing haptoral tentacles of Hamatopeduncularia spp. and on the status of these tentacles in taxonomic studies. Possible evolutionary trends in these gill parasites are suggested. Consideration is given to salinity tolerances by the parasites, to possible age-related changes in host susceptibility and to genetic differences between catfishes, as explanations for differences in the distribution of these parasites on large and small hosts and on hosts from the Brisbane River and from Moreton Bay.

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