Schistosoma haematobium (Bladder Fluke): Life Cycle and Morphology

The tropical parasitic disease schistosomiasis haematobium requires the snail vector Bulinus truncatus to successfully complete its life cycle. While in the snail, the parasite exists as a cercarial producing sporocyst. The infection of snails by the parasite is very specific, different subpopulations (strains) of parasites are not always compatible with snails from different geographic regions. It is not always known if the incompatibility is due to failure of penetration of snails by parasites or to subsequent destruction of sporocysts by infected snails. In these experiments, sporocysts from compatible sporocyst-snai1 infections were surgically transplanted into snails not compatible with the parasite.Egyptian snails (B. truncatus) which had been infected with the Egyptian strain of Schistosoma haematobium were dissected after five weeks. Sporocysts were removed from the hepatopancreas and surgically implanted into B. truncatus snails from Egypt (compatible), Morocco and Niger (incompatible). After four days, these snails were dissected and the transplanted sporocysts were prepared for electron microscopy. Each sample was also tested for glycogen contents by the Thiery Silver test.

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The amount of acetylcholinesterase on the parasite surface reflects the differential sensitivity of schistosome species to metrifonate

Parasitology ◽

10.1017/s0031182000068244 ◽

1994 ◽

Vol 108 (2) ◽

pp. 153-160 ◽

Cited By ~ 29

Author(s):

M. Camacho ◽

R. Tarrab-Hazdai ◽

B. Espinoza ◽

R. Arnon ◽

A. Agnew

Keyword(s):

Life Cycle ◽

Ache Activity ◽

Schistosoma Haematobium ◽

Adult Stage ◽

Molecular Form ◽

Differential Sensitivity ◽

Molecular Forms ◽

Ache Inhibitors ◽

Schistosoma Bovis

SUMMARYAcetylcholinesterase (AChE) is present in all stages of the life-cycle of schistosomes and is located in muscle and on the surface of the parasite. Metrifonate is a drug that inhibits AChE. We compared the AChEs from three schistosome species (Schistosoma mansoni, Schistosoma haematobium and Schistosoma bovis) that have different susceptibilities to metrifonate in vivo. Sensitivities to AChE inhibitors were similar. The subunits of AChE were 110 kDa and 76 kDa and the dominant molecular form of AChE was a G2 form in all three species. This was the major form on the tegument while additional molecular forms were associated with the internal tissues. Differences in relative amounts of AChE activity between these species were found in the adults but not in the schistosomula. At the adult stage the major difference between species lay in the relative amounts of AChE activity in their teguments. S. haematobium teguments carried 20 times and S. bovis 6·9 times the activity present on S. mansoni teguments. These quantitative differences associate with the relative sensitivities of these species to metrifonate.

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Ultrastructural analysis of “Sensory” surface nerve endings and “putative” neurotransmitter sites in Schistosoma mansoni Miracidia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156791 ◽

1989 ◽

Vol 47 ◽

pp. 962-963

Author(s):

Betty Ruth Jones ◽

Steve Chi-Tang Pan

Keyword(s):

Nervous System ◽

Life Cycle ◽

Schistosoma Mansoni ◽

Snail Host ◽

Complex Life Cycle ◽

Rational Approach ◽

Effective Control ◽

The Social ◽

Social And Economic Development ◽

Basic Biology

INTRODUCTION: Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease and thus the number of infections are increasing.Our knowledge of the basic biology of the parasites causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes. The future of the entire life cycle depends on the capacity and ability of this organism to locate and enter a suitable snail host for further development, Little is known about the nervous system of the miracidium of Schistosoma mansoni and of other trematodes. Studies indicate that miracidia contain a well developed and complex nervous system that may aid the larvae in locating and entering a susceptible snail host (Wilson, 1970; Brooker, 1972; Chernin, 1974; Pan, 1980; Mehlhorn, 1988; and Jones, 1987-1988).

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A freeze-fracture-etched study of the physarum polycephalum plasma membrane during early formation of the macroplasmodial stage

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147570 ◽

1993 ◽

Vol 51 ◽

pp. 346-347

Author(s):

Randolph W. Taylor ◽

Henrie Treadwell

Keyword(s):

Plasma Membrane ◽

Life Cycle ◽

Growth Phase ◽

Filter Paper ◽

Physarum Polycephalum ◽

Freeze Fracture ◽

Petri Dish ◽

Wire Screen ◽

Wide Mouth ◽

Sterile Filter

The plasma membrane of the Slime Mold, Physarum polycephalum, process unique morphological distinctions at different stages of the life cycle. Investigations of the plasma membrane of P. polycephalum, particularly, the arrangements of the intramembranous particles has provided useful information concerning possible changes occurring in higher organisms. In this report Freeze-fracture-etched techniques were used to investigate 3 hours post-fusion of the macroplasmodia stage of the P. polycephalum plasma membrane.Microplasmodia of Physarum polycephalum (M3C), axenically maintained, were collected in mid-expotential growth phase by centrifugation. Aliquots of microplasmodia were spread in 3 cm circles with a wide mouth pipette onto sterile filter paper which was supported on a wire screen contained in a petri dish. The cells were starved for 2 hrs at 24°C. After starvation, the cells were feed semidefined medium supplemented with hemin and incubated at 24°C. Three hours after incubation, samples were collected randomly from the petri plates, placed in plancettes and frozen with a propane-nitrogen jet freezer.

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Software Development Life Cycle

Computer Programming with C++ ◽

10.1017/9781316534489.021 ◽

2018 ◽

pp. 999-1001

Keyword(s):

Life Cycle ◽

Software Development ◽

Development Life Cycle ◽

Software Development Life Cycle

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A Spreadsheet Life Cycle Cost Model for System Modernization Studies

The Journal of Cost Analysis ◽

10.1080/08823871.1994.10462284 ◽

1994 ◽

Vol 11 (1) ◽

pp. 47-56

Author(s):

Virginia C. Day ◽

Zachary F. Lansdowne ◽

Richard A Moynihan ◽

John A. Vitkevich

Keyword(s):

Life Cycle ◽

Life Cycle Cost ◽

Cost Model

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Schistosomal Appendicitis in Pregnancy

Swiss Surgery ◽

10.1024/1023-9332.8.3.121 ◽

2002 ◽

Vol 8 (3) ◽

pp. 121-122 ◽

Cited By ~ 9

Author(s):

Halkic ◽

Abdelmoumene ◽

Gintzburger ◽

Mosimann

Keyword(s):

Acute Appendicitis ◽

Schistosoma Haematobium ◽

Acute Inflammation ◽

The Body ◽

Parasitic Infections ◽

Common Complication ◽

Surgical Infection ◽

High Prevalence ◽

Potential Challenge ◽

In Pregnancy

Acute appendicitis is the most common acute surgical infection during pregnancy. Although usually pyogenic in origin, parasitic infections account for a small percentage of cases. Despite the relatively high prevalence of acute appendicitis in our environment, it is not commonly associated with schistosomiasis. We report here the association of pregnancy and appendicitis caused by Schistosoma haematobium. Schistosomiasis is very common complication of pregnancy in hyperendemic areas. Schistosome egg masses can lodge throughout the body and cause acute inflammation of the appendix, liver and spleen. Congestion of pelvic vessels during pregnancy facilitates passage of eggs into the villi and intervillous spaces, causing an inflammatory reaction. Tourism and immigration make this disease a potential challenge for practitioners everywhere.

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