Gas content of swim bladder of Wallago attu and oxygen consumption in Isoparorchis hypselobagri (Trematoda).

The swim bladder gas of Wallago attu contains O2 (22-58 mm Hg) and the presence or absence of Isoparorchis hypselobagri does not influence the O2 content of the swim bladder. Glucose increases the O2 consumption of I. hypselobagri by 50%. With the passage of in vitro culture time, the rate of O2 consumption gradually decreases to the extent of 64% on the 40th day. The optimal temperature for O2 consumption is 30 degrees C beyond which the rise in temperature is detrimental to the fish trematode as manifested by the decrease in their O2 consumption.     

Opisthorchis viverrini: ultrastructure and cytochemistry of the glycocalyx of the tegument

The ultrastructure and cytochemistry of the glycocalyx of the tegument of Opisthorchis viverrini during maturation from newly excysted juvenile to adult stages were investigated using colloidal iron, ruthenium red and lectin stainings. The results showed that the glycocalyx was intensely stained by the first two dyes, thus indicating the presence of relatively high amounts of negative charges. However, the thickness and intensity of the staining decreased during the fluke's maturation. Binding studies using lectin probes on the surface of adult parasites showed that binding sites for Canavalia ensiformis (Con A), Triticum vulgaris (WGA) and Ricinus communis I (RCA I) were present in relative large amounts on the glycocalyx of the adult tegument, whereas those for Dolichos biflorus (DBA) were relatively fewer in number, and those for Ulex europaeus I (UEA I) were absent. The binding patterns of Con A, WGA, RCA I and DBA were generally similar, and the reaction product was uniformly distributed over the dorsal and ventral surfaces of the parasite's body. These bindings, therefore, indicate the presence of D-mannose/D-glucose, N-acetyl-D-glucosamine/sialic acid, D-galactose and N-acetyl-D-galactosamine residues on the glycocalyx of the adult tegument.     

Fasciola hepatica: ultrastructure and histochemistry of the glycocalyx of the tegument.

The morphology and histochemistry of the glycocalyx of the tegument was investigated by electron microscopy. The results showed that both the morphology and histochemistry of the glycocalyx varied depending on the environment immediately prior to fixation and also on postfixation treatments. Conventional electron microscope fixation appeared to preserve only about half the total thickness of the glycocalyx, and only histochemical tests applied en bloc gave a true morphological and histochemical picture. The glycocalyx, therefore, consists of two parts, an inner continuous layer which is tightly bound to the apical plasma membrane and is always preserved, and an outer fibrillar layer, which is not always preserved by conventional fixation. Both layers are anionic and carbohydrate-rich and therefore contain glycoproteins and sialic acids. The surface of Fasciola hepatica, therefore, has morphological and chemical features very like those proposed for the “greater membrane” by Lehninger.     

Taenia crassiceps: Regional variations in ultrastructure and evidence of endocytosis in the cysticercus' tegument

Regional variations in the thickness of the tegument, in the morphology of microtriches and mitochondria, in the distribution of dense bodies, smooth micropinocytotic vesicles (SMVs), and coated micropinocytotic vesicles (CMVs) have been shown for the cysticercus of Taenia crassiceps. The number of SMVs and CMVs present in the syncytial layer are in inverse proportion to each other, the former being more numerous in the bladder wall and upper part of the invagination canal and the latter in the lower part of the canal and the rostellar region. Tegumental cells contain numerous granular endoplasmic reticulum-Golgi complexes involved in the synthesis of both primary lysosomes and dense bodies. Vesicles characteristic of various stages of heterolysosomes are present and show regional variations in numbers and size. Acid phosphatase activity (EC 3.1.3.2) is present on the tegumental surface, and within the Golgi complex, primary lysosomes, and heterophagosomes of the tegumental cells. CMVs are reported for the first time in the tegument of any helminth and have characteristics similar to CMVs in other tissues. T. crassiceps, therefore, because of the presence of both SMVs and CMVs, is a unique model system for the study of basic mechanisms of endocytosis.     

Schistosoma haematobium: the effect of Astiban on the cell composition and ultrastructure of the vitelline gland and the ultrastructure of the tegument and gastrodermis

Treatment of Schistosoma haematobium (Nigerian strain) in hamsters with a single dose of 40 mg/kg of Astiban caused a reduction in the number of S1, S2, and S3 vitelline cells and an increase in S4 cells. Following seven daily doses of the drug, a marked reduction in S1 cells and a complete loss of S2 and S3 cells occurred such that 95% of the cells were S4 cells, all of which were structurally abnormal. Coagulation and disintegration of the protein granules of the vitelline droplets occurred with increase in lipid droplets, swelling of the nuclear membrane and an increase in cytosegresomes. Blebbing of the tegument in both sexes occurred following a single treatment and vacuolation of the basal infolds and alterations to the mitochondria also resulted, but severe erosion of the tegument was rare even following repeated drug treatment. Damage to the gastrodermis was severe with the development of autophagic vacuoles containing whorls of myelin and sequestered portions of damaged tissue. The degree of damage increased with the number of drug treatments.     

The action of fenasal on the ultrastructure of the tegument in Caryophyllaeus laticeps cestodes

The effect of the anthelmintic preparation fenasal on the fine structure of tegument of the cestode Caryophyllaeus laticeps, a parasite of Cyprinidae, was studied in vitro. 10 mcg/ml concentration of fenasal causes numerous evaginations of the external cytoplasmic layer in the scolex of helminth. Inside these formations there are granules of secretion, mitochondria, vacuoles. At the same time microtrichia disappear from the surface, cytoplasmic layer gets thinner and its mitochondria degenerate. In the middle part of the body the number of microtrichia decreases, the layer of tegumental cells swells and conformational condition of its mitochondria changes. The degree of injury depends on the exposition time which was from 0 to 4 hours.     

Spermiogenesis and spermatozoon ultrastructure of the cranial digenean Troglotrema acutum (Leuckart, 1842)

Ultrastructure of spermiogenesis and the main characters of the mature spermatozoon of Troglotrema acutum are described by means of transmission electron microscopy. Specimens were obtained from the nasolacrimal sinuses of an American mink (Mustela vison). Spermiogenesis in T. acutum follows the general pattern of digeneans. The zone of differentiation is a conical-shaped area bordered by cortical microtubules and delimited at its base by a ring of arched membranes. This area contains 2 centrioles associated with striated rootlets and an intercentriolar body between them. The centrioles develop 2 free flagella that grow ortogonally to the median cytoplasmic process. The posterior flagellar rotation and proximodistal fusion of the free flagella with the median cytoplasmic process originate the spermatozoon. The mature spermatozoon of T. acutum is characterized by the presence of 2 axonemes of different lengths presenting the 9+'1' trepaxonematan pattern, 2 bundles of parallel cortical microtubules, 2 mitochondria, a nucleus, and granules of glycogen. These ultrastructural characters are compared with other digenean species previously studied and the importance of different spermatological features is discussed.     

Fasciola hepatica: basal infolds and associated vacuoles of the tegument.

The tegument of Fasciola hepatica has been shown to contain long invaginations of its basal plasma membrane, hereafter called basal infolds. Associated with the membranes of the infolds, and with the apical and basal plasma membranes, is a Na⁺ K⁺ ATPase (EC 3.6.1.3). Furthermore, polymorphic masses of acid mucopolysaccharide lie close to or against the sides of the infolds and the basal plasma membrane and also fill cytoplasmic tubules which connect the tegument with the tegumental cells. Fixation and incubation of flukes in hypertonic and hypotonic media have shown that the infolds respond to changes in external osmolarity by collapsing in the former and swelling in the latter. This is not simply a passive response, however, since the infolds return to near normal configuration and morphology within 1 hr in either hypertonic or hypotonic media, even though the whole fluke may be shrunken or turgid depending on medium osmolarity. The tegument, therefore, has many of the characteristics of a transporting epithelium. A theory outlining the possible mode of operation of the tegument as a transporting epithelium is proposed on the basis of the present structural, chemical, and physiological findings combined with current ideas of the role and functioning of standing gradients, and forward and backward channel systems in other transporting epithelia.     

Bacterial diversity in a nonsaline alkaline environment: heterotrophic aerobic populations

Heterotrophic populations were isolated and characterized from an alkaline groundwater environment generated by active serpentinization, which results in a Ca(OH)2-enriched, extremely diluted groundwater with pH 11.4. One hundred eighty-five strains were isolated in different media at different pH values during two sampling periods. To assess the degree of diversity present in the environment and to select representative strains for further characterization of the populations, we screened the isolates by using random amplified polymorphic DNA-PCR profiles and grouped them based on similarities determined by fatty acid methyl ester analysis. Phenotypic characterization, determinations of G+C content, phylogenetic analyses by direct sequencing of 16S rRNA genes, and determinations of pH tolerance were performed with the selected isolates. Although 38 different populations were identified and characterized, the vast majority of the isolates were gram positive with high G+C contents and were affiliated with three distinct groups, namely, strains closely related to the species Dietzia natrolimnae (32% of the isolates), to Frigoribacterium/Clavibacter lineages (29% of the isolates), and to the type strain of Microbacterium kitamiense (20% of the isolates). Other isolates were phylogenetically related to strains of the genera Agrococcus, Leifsonia, Kytococcus, Janibacter, Kocuria, Rothia, Nesterenkonia, Citrococcus, Micrococcus, Actinomyces, Rhodococcus, Bacillus, and Staphylococcus. Only five isolates were gram negative: one was related to the Sphingobacteria lineage and the other four were related to the alpha-Proteobacteria lineage. Despite the pH of the environment, the vast majority of the populations were alkali tolerant, and only two strains were able to grow at pH 11.     

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.     

Speed-mapping of arsenic distribution in the tissues of earthworms inhabiting arsenious soil.

We have examined the distribution of arsenic in the metal-sequestering chloragogenous tissue of a population of the earthworm, Lumbricus rubellus, exposed to the metalloid in its natural environment. The localization technique was qualitative digital X-ray speed mapping (2 minute total acquisition time) of fresh air dried tissue smears. Arsenic was located in association with sulphur in a discrete chloragocytic compartment; it was not detected in the phosphate-rich chloragosome granules. In earthworm tissues arsenic was distributed according to its sulphydryl-seeking trivalent form, not as the phosphate-resembling pentavalent form.     

Spermiogenesis and spermatozoon ultrastructure of the digenean Neoapocreadium chabaudi (Apocreadiidae), a parasite of Balistes capriscus (Pisces,Teleostei)

Spermiogenesis and the ultrastructural organization of the spermatozoon of the digenean Neoapocreadium chabaudi are described by means of transmission electron microscopy.Spermiogenesis follows the usual pattern found in the digeneans. It begins with the formation of a zone of differentiation bordered by cortical microtubules, characterized by the presence of an intercentriolar body composed of seven electron-dense plates situated between two striated rootlets and two centrioles. These centrioles give rise to two free flagella. Later, both flagella undergo a rotation of 90° and fuse with the median cytoplasmic process. Spermiogenesis finishes when the ring of arched membranes constricts. The mature spermatozoon of N. chabaudi is characterized by the presence of 2 axonemes of different lengths presenting the 9 + “1” trepaxonematan pattern, 2 bundles of parallel cortical microtubules, 2 mitochondria, a nucleus, and granules of glycogen. Nevertheless, several characters such as the morphology of sperm extremities and the presence of spinelike bodies allow us to distinguish N. chabaudi from other digenetic trematodes. The present paper provides the first ultrastructural results of a digenean belonging to the family Apocreadiidae that may be useful for the understanding of digenean relationships and phylogenetic studies.     

Bacterial communities inhabiting the healthy tissues of two Caribbean reef corals: interspecific and spatial variation

Bacterial communities inhabiting healthy tissues of the reef-building corals Diploria strigosa and Montastraea annularis were evaluated across a human-induced environmental gradient along the southern coast of Curaçao, Netherlands Antilles. Variations in bacterial communities inhabiting coral tissues were determined using terminal restriction fragment length polymorphisms (T-RFLP) of 16S rRNA genes, and the ¹⁵N value of coral tissue was used to assess the relative amount of human contaminants at each reef locality. Bacterial communities of D. strigosa were more variable than M. annularis, but there were no systematic differences in the populations of healthy M. annularis and D. strigosa. The ¹⁵N value of coral tissues showed as much as a 1.5 increase in the impacted versus the non-impacted localities. While M. annularis showed no significant variation in bacterial community structure due to local reef conditions, the bacterial communities of D. strigosa showed dramatic shifts in community structure. The most abundant bacterial taxa inhabiting D. strigosa display increased dominance at impacted localities. By linking variations in microbial communities with an understanding of variations in local environmental conditions, this study provides a means of assessing potential factors that may impact the microbial habitat of coral tissues as well as overall reef health.     

Topography and ultrastructure of the tegument of Bucephalus anguillae (Digenea: Bucephalidae), a parasite of the European eel Anguilla anguilla (Osteichthyen: Anguillidae)

The tegumental ultrastructure of the intestinal fluke Bucephalus anguillae was studied with the use of scanning and transmission electron microscopy. The surface of the tegument is covered by transverse ridges from which protrude numerous closely packed, digitated, and claw-shaped spines. Cobblestone-like units of the tegument were observed on the crescent-shaped formation of the rhynchus and at the posterior part of the body. Three types of sensory structures were examined, i.e., 2 uniciliated receptors and 1 without cilia. As anterior-posterior differences were observed, particular attention was given to spines and sensory receptors. Spine insertion zones and average cilia length are variable between anterior and posterior tegument areas. Ultrastructural study revealed that the tegument of B. anguillae has a typical syncytial organization with a distal cytoplasm lying over a basal matrix and cytons below. Cytoplasmic bridges allowed transit of secretory vesicles and granules. Diagrams of spines and sensory receptors were made to help in understanding the nature of these structures.     

Metabolic enzymes in seasonally acclimatized and cold acclimated rufous-collared sparrow inhabiting a Chilean Mediterranean environment

Due to the higher energy requirements of birds during winter, it is predicted that the activities of metabolic enzymes （e.g., citrate synthase, CS and cytochrome C oxidase, COX） should increase in tandem with increases in rates of energy expendi ture （e.g., basal metabolic rate, BMR）. However, there is mixed support for the hypothesis of enzymatic acclimatization. Fur thermore, there is little information about the effect of ambient temperature on energetics and tissue enzyme activity levels in passerines inhabiting seasonal Mediterranean environments. In this study we evaluated the interplay between BMR and enzyme activities of freshly caught individuals of the passerine Zonotrichia capensis in winter and summer in a Mediterranean environment from central Chile, and also in warm （30℃） and cold （15℃） labacclimated birds. The results revealed a lack of seasonal variation in BMR, thermal conductance and in the activity of CS and COX. However, we found higher BMR and lower thermal conductance in coldacclimated than in warmacclimated birds. Also, total CS activity was higher in the flight muscles of coldacclimated than in warmacclimated birds. We found also a significant correlation between BMR and total CS activity in pectoral muscle. Although some authors have suggested that BMR mainly depends on the metabolic intensity and mass of internal organs, our results revealed that skeletal muscles such as the flight muscles may also affect BMR. Finally, differences in the accli mation and acclimatization responses in Rufouscollared sparrows suggest that largescale oscillations in the physical environment might maintain the capacity for flexibility in thermogenic traits through generations .