An unusual structural organization to the gut of a digenetic trematode, Fellodistomum fellis

Parasitology ◽  
1982 ◽  
Vol 85 (1) ◽  
pp. 53-60 ◽  
Author(s):  
D. W. Halton
Keyword(s):  
Cell Surface ◽  
Elemental Analysis ◽  
Structural Organization ◽  
Digenetic Trematode ◽  
Blood Components ◽  
Ultrastructural Examination ◽  
Anterior Portion ◽  
Digestive Cells ◽  
Histochemical Tests ◽  
Host Blood

SUMMARYAn ultrastructural examination of Fellodistomum fellis has revealed that the caecal lining consists of 2 distinct components: (a) cup-shaped digestive cells and (b) a pleomorphic layer of cytoplasm which supports and separates individual digestive cells. The digestive cells sequester host blood components within apical pockets formed by lamellated extensions of the cell surface, and undergo asynchronous, cyclical transformations in morphology associated with extracellular digestion and with the extrusion to the gut lumen of pigmented digestive residues. Histochemical tests and elemental analysis of the pigment suggest that it is a ferripor-phyrin, haematin. In the anterior portion of the caecum the supporting cytoplasmic layer is in continuity with the oesophageal tegument and snares the same ultrastructure. It is concluded that the digestive cells are supported by an extension of the foregut tegument.

Morphological and elemental analysis of isolated incubated frog retina-choroid

1984 ◽  
Vol 42 ◽  
pp. 298-299
Author(s):  
B. J. Panessa-Warren ◽  
J. B. Warren ◽  
H. W. Kraner
Keyword(s):  
Elemental Analysis ◽  
Pigment Epithelium ◽  
Human Retina ◽  
Healthy Individuals ◽  
Anterior Portion ◽  
Pathological Conditions ◽  
Frog Retina ◽  
Isolated Retina ◽  
Vertebrate Eye ◽  
Retina Pigment Epithelium

Our previous studies have demonstrated that abnormally high amounts of calcium (Ca) and zinc (Zn) can be accumulated in human retina-choroid under pathological conditions and that barium (Ba), which was not detected in the eyes of healthy individuals, is deposited in the retina pigment epithelium (RPE), and to a lesser extent in the sensory retina and iris. In an attempt to understand how these cations can be accumulated in the vertebrate eye, a morphological and microanalytical study of the uptake and loss of specific cations (K, Ca,Ba,Zn) was undertaken with incubated Rana catesbiana isolated retina and RPE preparations. Large frogs (650-800 gms) were dark adapted, guillotined and their eyes enucleated in deep ruby light. The eyes were hemisected behind the ora serrata and the anterior portion of the eye removed. The eyecup was bisected along the plane of the optic disc and the two segments of retina peeled away from the RPE and incubated.

scholarly journals Gastrodermis ultrastructure of the different life stages of the polyopisthocotylean monogenean gill parasite Discocotyle sagittata

2021 ◽  
Author(s):  
Joanne Cable ◽  
Mohamed Mohamed El-Naggar
Keyword(s):  
Salmo Trutta ◽  
Structural Organization ◽  
Alimentary Tract ◽  
Blood Feeding ◽  
Life Stages ◽  
Variable Size ◽  
Digestive Cells ◽  
Gill Parasite ◽  
Apical Cytoplasm ◽  
Gill Lamellae

AbstractThe polyopisthocotylean Discocotyle sagittata is a blood-feeding monogenean that infects the gill lamellae of rainbow trout, Oncorhynchus mykiss, and brown trout, Salmo trutta. The ultrastructure of their alimentary tract, at different stages of the life cycle, was previously unknown. Here, we show that the gastrodermis of the oncomiracidium, subadult, and adult D. sagittata follows the same structural organization as that of other blood-feeding polyopisthocotyleans, being composed of digestive cells alternating with a connecting syncytium. Digestive cells of the oncomiracidium are found in three developmental forms: undifferentiated, developing differentiated, and differentiated (presumably functioning) cells whereas those of adult and subadult are present in a single functioning state with variable size and content. The apical cytoplasm of adult digestive cells forms conical outgrowths, a feature which is absent in the oncomiracidium. The connecting syncytium of the oncomiracidium has no evidence of metabolic activity, while that of adult and subadult is metabolically active. The lamellae of the connecting syncytium of adults and subadults are more numerous and larger, and their terminal portions are expanded, compared with those of the oncomiracidium. Parallel, tubular, membranous structures are characteristic of the apical cytoplasm of the connecting syncytium of the oncomiracidium. Luminal lamella in the oncomiracidium, subadult, and adult form balloon-like structures enclosing some luminal contents, but those of the oncomiracidium are larger, bounded by nucleated cytoplasmic layer, and enclose more luminal contents. The possible functions of these structures and mechanism of digestion in both oncomiracidium and adult are discussed.

scholarly journals Trypanosoma cruzi: cell charge distribution

1985 ◽  
Vol 27 (6) ◽  
pp. 312-317 ◽  
Author(s):  
T. Langenbach
Keyword(s):  
Trypanosoma Cruzi ◽  
Charge Distribution ◽  
Surface Coat ◽  
Blood Components ◽  
Host Blood ◽  
Selection Of

Differences in cell charge between epimastigote and trypomastigote populations were compared in Y, Cl and Colombiana strains of T. cruzi. Trypomastigote populations were more homogenous in relation to cell charge than epimastigotes. This homogeneity of cell charge was not the result of the selection of trypomastigote sub-populations by the host immunosystem, but may be the result of a surface coat formed by host blood components.

Apicoporus haificum (Gymnodiniaceae), a new dinoflagellate species from sandy sediments of the Mediterranean Sea (Israel coast)

Phytotaxa ◽  
2019 ◽  
Vol 404 (7) ◽  
pp. 287
Author(s):  
МAXIM А. KRAKHMALNYI ◽  
ALEKSANDR F. KRAKHMALNYI
Keyword(s):  
Cell Surface ◽  
Light Microscopy ◽  
Mediterranean Sea ◽  
Cross Section ◽  
Distal Part ◽  
Eastern Coast ◽  
Anterior Portion ◽  
The Mediterranean ◽  
The Right ◽  
Sandy Sediments

A new dinoflagellate species (Dinophyceae, Gymnodiniales)—Apicoporus haificum Krachmalny sp. nov. was described on a basis of thorough light microscopy studies. The species was found in sandy sediments (water-filled spaces between sand grains) on the eastern coast of the Mediterranean Sea (HaCarmel beach, Haifa, Israel). Apicoporus haificum possesses the following features: cells elongated (with length exceeding width by 3.1–3.8 times), lanceolate in dorsoventral projection, roundish in cross-section with slight dorsoventral compression, asymmetrical, slightly curved to the right, with antapical depression. Epicone asymmetrical, somewhat umbonate, with a small hook-shaped protrusion on the apex. Cingulum displaced, descending by 1/3 cell’s length, its distal part almost parallel to the anterior portion of sulcus. Sulcus narrow, shallow, extends from the apex to the antapical depression, with apical groove. Cell surface covered with longitudinal striations that converge on the apex and on the antapical protrusion. Chloroplasts absent. Dimensions: 75.3±2.2 μm in length, 21.4±1.5 μm in width. Comparison of A. haificum to morphologically similar Apicoporus glaber and Amphidinium scissum is discussed.

Echinococcus granulosus: the effects of praziquantel, in vivo and in vitro, on the ultrastructure of equine strain murine cysts

Parasitology ◽  
1988 ◽  
Vol 96 (2) ◽  
pp. 323-336 ◽  
Author(s):  
K. Sylvia Richards ◽  
D. L. Morris ◽  
D. Daniels ◽  
E. M. Riley
Keyword(s):  
Echinococcus Granulosus ◽  
Structural Organization ◽  
Drug Withdrawal ◽  
Serum Levels ◽  
Germinal Layer ◽  
Ultrastructural Examination ◽  
Hepatic Cysts ◽  
Drug Treatments

SummaryPraziquantel (500 mg/kg) administered orally to BALB/c mice with secondary equine E. granulosus daily for 21, 30 or 30 + 30 days without the drug resulted in the majority of cysts, using bench criteria of turgidity and eosin exclusion, being assessed as ‘alive’. Ultrastructural examination of 54 of these ‘alive’ cysts did not support this conclusion. They all showed increased vesiculation of the germinal layer leading, in many, to the loss of its integrity. Increased mitochondrial numbers occurred frequently. The longer drug treatments appeared to have greater effects on the germinal layer of ‘alive’ cysts and there was no detectable re-establishment of structural organization within 30 days after drug withdrawal. Subjectively, there was no substantial difference between cysts from 4-month and 9-month infections or between affected peritoneal and hepatic cysts. Tissue from collapsed cysts was necrotic. Peak serum levels of praziquantel (6430–6136 μg/l) occurred 5–10 min after drug administration (500 mg/kg) and dropped rapidly to less than 10 μg/l at 3 h. In an in vitro study at praziquantel concentrations of 1000 and 5000 μg/l over a 10-day period, most cysts were judged ‘alive’ by bench criteria but showed ultrastructurally a time- and concentration-dependent loss of integrity identical to that seen in vivo. Turgidity and eosin exclusion therefore underestimate the effect of praziquantel and the results indicate that in vitro experiments can fulfil a legitimate preliminary role in a hydatid chemotherapy programme.

The role of algal antigenic determinants in the recognition of potential algal symbionts by cells of Chlorohydra

1979 ◽  
Vol 35 (1) ◽  
pp. 367-379
Author(s):  
R.R. Pool
Keyword(s):  
Cell Surface ◽  
Algal Cell ◽  
Antigenic Determinants ◽  
Digestive Cells ◽  
Green Hydra ◽  
Algal Symbionts ◽  
Two Systems

Algal cells grown in the green hydra Chlorohydra viridissima were shown to possess characteristic antigenic determinants not found in algae cultured in vitro. These antigenic determinants, including those localized on the algal cell surface, were shown to be responsible for the phagocytic recognition of potential algal symbionts by digestive cells of Chlorohydra. The results of this study indicate the existence of two systems governing phagocytosis in Chlorohydra, one specific for algal cells grown in hydra, another governing the uptake of other particles by the hydra digestive cells.

scholarly journals Mialostatin, a Novel Midgut Cystatin from Ixodes ricinus Ticks: Crystal Structure and Regulation of Host Blood Digestion

2021 ◽  
Vol 22 (10) ◽  
pp. 5371
Author(s):  
Jan Kotál ◽  
Michal Buša ◽  
Veronika Urbanová ◽  
Pavlína Řezáčová ◽  
Jindřich Chmelař ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ixodes Ricinus ◽  
Cathepsin L ◽  
Blood Protein ◽  
Hard Tick ◽  
Blood Proteins ◽  
Digestive Cells ◽  
Cysteine Cathepsins ◽  
Host Blood

The hard tick Ixodes ricinus is a vector of Lyme disease and tick-borne encephalitis. Host blood protein digestion, essential for tick development and reproduction, occurs in tick midgut digestive cells driven by cathepsin proteases. Little is known about the regulation of the digestive proteolytic machinery of I. ricinus. Here we characterize a novel cystatin-type protease inhibitor, mialostatin, from the I. ricinus midgut. Blood feeding rapidly induced mialostatin expression in the gut, which continued after tick detachment. Recombinant mialostatin inhibited a number of I. ricinus digestive cysteine cathepsins, with the greatest potency observed against cathepsin L isoforms, with which it co-localized in midgut digestive cells. The crystal structure of mialostatin was determined at 1.55 Å to explain its unique inhibitory specificity. Finally, mialostatin effectively blocked in vitro proteolysis of blood proteins by midgut cysteine cathepsins. Mialostatin is likely to be involved in the regulation of gut-associated proteolytic pathways, making midgut cystatins promising targets for tick control strategies.

The diet and gastrodermal ultrastructure of polystomatid monogeneans infecting chelonians

Parasitology ◽  
1989 ◽  
Vol 98 (2) ◽  
pp. 265-273 ◽  
Author(s):  
K. M. Allen ◽  
R. C. Tinsley
Keyword(s):  
Epithelial Cells ◽  
Blood Feeding ◽  
Intracellular Accumulation ◽  
X Ray ◽  
Intracellular Digestion ◽  
Transmission Electron ◽  
Supportive Role ◽  
Histochemical Tests ◽  
High Concentrations ◽  
Host Blood

SUMMARYAll polyopisthocotylean monogeneans previously studied, including representatives of the Polystomatidae infecting anuran amphibians, feed on host blood. However, the present analysis of species of Polystomoides, Polystomoidella and Neopolystoma, polystomatids which infect chelonian reptiles, has shown that this group has diverged nutritionally from related parasites. Histochemical tests failed to demonstrate haemoglobin in the gut caeca, and X-ray microanalysis confirmed the absence of haematin (or high concentrations of bound iron) in the gastrodermis. The chelonian poly-stomatids (and also the single monogenean which infects a mammal, Oculotrema hippopotami) feed on epithelial cells and mucus, the diet typical of monopisthocotyleans. Transmission electron microscopy revealed the same gastrodermal architecture in representatives of Polystomoides from Africa, N. America and S.E. Asia. The organization of the caecal epithelium conforms with that of blood-feeding polyopisthocotyleans, with two components: lamellated cells responsible for intracellular digestion interspersed with elements of a non-lamellated connecting syncytium. In other polyopistho-cotyleans, the syncytium probably has a skeletal, supportive role, related to the problems of intracellular accumulation of haematin, but in polystomatids infecting chelonians the syncytium is extremely reduced and its presence probably reflects an ancestry amongst blood-feeding relatives. The utilization of the presumably more primitive monogenean diet of epithelial cells and mucus by chelonian polystomatids may be related to the scarcity of superficial blood vessels in their oral and urinary bladder habitats.

Radioactive studies on the feeding of larvae, nymphs, and adults of the cattle tick,Boophilus microplus(Canestrini)

Parasitology ◽  
1968 ◽  
Vol 58 (2) ◽  
pp. 415-430 ◽  
Author(s):  
G. W. Seifert ◽  
P. H. Springell ◽  
R. J. Tatchell
Keyword(s):  
Life Cycle ◽  
Technical Assistance ◽  
Boophilus Microplus ◽  
Red Cells ◽  
Cattle Tick ◽  
Blood Components ◽  
Larval Stages ◽  
Adult Females ◽  
Host Blood ◽  
Radioactivity Levels

The erythrocytes and plasma of a British and Brahman crossbred steer were labelled with51Cr and125I respectively. The radioactivity levels were subsequently maintained as constant as feasible by injecting the steers with calculated amounts of the appropriate labelled material on 3 consecutive days. The steers had previously been heavily infested withBoophilus microplusto ensure that all stages in the parasite's life-cycle would be present during the 4-day period, when the steers were being treated with isotopes.Various stages ofB. micropluslarvae, nymphs and adults were collected and the uptake of red cells and plasma at each stage assessed by radioassay. In certain calculations, corrections were made for the uptake of blood fractions before the animals were made radioactive.A relationship between the weight of the tick and its dietary intake was established. At all the stages of larval and nymphal feeding the plasma content of the diet was greater than that of the host blood. However, erythrocytes were detectable even in the earliest larval stages examined. Dropped fully engorged adult females contained more red cells per individual, and generally also more plasma, than engorged ticks removed from the host.Fully engorged adult females took up as much as twice their own weight of blood components, but in none of the earlier stages did the tick concentrate its blood meal.No obvious differences could be demonstrated statistically between the behaviour of the parasites on the two hosts. However, indications are that recently attached larvae took up more erythrocytes from the British animal.We wish to thank Messrs A. K. Duffield, A. J. Short, B. Wilson, and Miss S. J. Shepherd, for skilful technical assistance.

THE CAPSULE AND ITS RELATION TO THE EMBRYOGENESIS OF THE ICHNEUMONID PARASITOID MESOLEIUS TENTHREDINIS MORL. IN THE LARCH SAWFLY, PRISTIPHORA ERICHSONII (HTG.) (HYMENOPTERA:TENTHREDINIDAE)

1960 ◽  
Vol 38 (4) ◽  
pp. 769-775 ◽  
Author(s):  
Joan F. Bronskill
Keyword(s):  
British Columbia ◽  
Blood Cells ◽  
Oxygen Supply ◽  
Outer Region ◽  
Germ Band ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly ◽  
Histochemical Tests ◽  
Inner Region ◽  
Host Blood

Eggs of the parasitoid Mesoleius tenthredinis Morl. from British Columbia develop and hatch in approximately 120 hours when reared at 23 ± 0.5 °C and a relative humidity of 72 ± 2% within field-collected larch sawfly (Pristiphora erichsonii (Htg.)) larvae from British Columbia and Newfoundland, and within laboratory-reared P. crichsonii larvae from British Columbia. However, they develop normally for only 70 to 80 hours within field-collected larvae from Manitoba as encapsulation of the developing eggs occurs and development ceases in the late germ band stage. The capsule is formed by an accumulation of host blood cells. During the formation of the capsule the innermost blood cells become flattened, fibrous, and enucleated, and eventually form a mass of concentric sheaths of non-cellular material. Thus, the definitive capsule is both cellular (outer region) and non-cellular (inner region). Histochemical tests indicate the presence of mucopolysaccharide in the capsule. It is suggested that the capsule inhibits the embryonic development of the parasitoid by interfering with its oxygen supply.

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