Carbohydrate metabolism in uninfected and trematode-infected snails Biomphalaria alexandrina and Bulinus truncatus (original) (raw)
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Hydrobiologia, 1970
The Warburg's manometric technique was used to measure the rate of oxygen consumption of the second generation of laboratory-reared snails, Biomphalaria alexandrina and Bulinus truncatus at two temperatures of 25° and 30°C. The individual weight of the experimental snails ranged between 40 and 78 mg for B. alexandrina, between 60 and 90 mg for B. truncatus. At 25°C, the uninfected snails B. alexandrina consumed oxygen at an average rate of 0.096 ± 0.020 ml/g wet wt/hr. The rate of oxygen consumption increased to an average of 0.147 ± 0.008 ml/g wet wt/hr for uninfected snails maintained at 30°C (about 53 per cent increase). The average RW value for uninfected snails maintained at 25°C was 0.80. The snail Bulinus truncatus showed higher oxygen requirements than the snail Biomphalaria alexandrina. At 25°C, it consumed oxygen at an average rate of 0.124 ± 0.016 ml/g wet wt/hr. At 30°C, the rate of oxygen consumption reached a value of 0.220 + 0.006 ml/g wet wt/hr. The average RQ for Bulinus truncatus maintained at 25°C was 0.87. The rate of oxygen consumption of the schistosome — infected Biomphalaria alexandrina snails, maintained at 25°C decreased to an average rate of 0.059 ± 0.010 ml/g wet wt/hr, (an average of 39 per cent decrease). The respiratory quotient (RQ) also decreased to an average value of 0.58. Further research is suggested to clarify the metabolism of both schistosome-infected and uninfected snails.
Journal of Parasitology Research
Only a fraction of the Biomphalaria and Bulinus snail community shows patent infection with schistosomes despite continuous exposure to the parasite, indicating that a substantial proportion of snails may resist infection. Accordingly, exterminating the schistosome intermediate snail hosts in transmission foci in habitats that may extend to kilometres is cost-prohibitive and damaging to the ecological equilibrium and quality of water and may be superfluous. It may be more cost effective with risk less ecological damage to focus on discovering the parameters governing snail susceptibility and resistance to schistosome infection. Therefore, laboratory bred Biomphalaria alexandrina and Bulinus truncatus snails were exposed to miracidia of laboratory-maintained Schistosoma mansoni and S. haematobium, respectively. Snails were examined for presence or lack of infection association with soft tissue and hemolymph content of proteins, cholesterol, and triglycerides, evaluated using standard...
Acta Tropica, 1996
Alterations in physiology of snail host induced by larval trematodes are generally interpreted like the results of a nutrient deprivation similar to starvation . However, few studies ) have been made on the nutritional physiology of snail hosts to assess the impact of trematode infection on nutrient assimilation and energy conversion. For Schistosoma mansoni pluri-infected Biomphalaria glabrata, have shown that during patent period food consumption and assimilation per unit snail weight were unaffected but gross conversion efficiency was sharply reduced. According to these authors, the decreased conversion efficiency of parasitized snails indicates that a significant portion of the food energy consumed by the host is utilized by the parasite for development and reproduction.
Journal of the Egyptian Society of Parasitology, 2013
The study examined the effects of larval trematode infection on the neutral lipid and phospholipid content of Biomphalaria alexandrina infected with Schistosoma mansoni. Uninfected snails were used as matched controls. As determined by qualitative high-performance silica gel thin-layer chromatography (HPTLC), the major neutral lipids present in the whole bodies and digestive gland-gonad complexes in both infected and uninfected snail populations were free sterols, free fatty acids, and triacylglycerols, and the major polar lipids were phosphatidylcho-line and phosphatidyl ethanolamine. Quantitative analysis by HPTLC with visible and UV scanning reflectance densitometry showed the snail's digestive gland lipid level was found to be almost halved in 20 days post infection; a more then 80% reduction being visible after the subsequent 40 and 60 days.
Experimental Parasitology, 2011
Snails' susceptibilities to infection with Schistosoma mansoni were determined through observation of infection rates, total cercarial production and tissue responses of the first generation (F1) of Biomphalaria alexandrina snails, originally collected from different Egyptian governorates (Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta) and responses were compared between groups. The emergence of cercariae for a 3-month period and the calculation of survival and infection rates, in control (Schistosome Biological Supply Center; SBSC) and infected snails were evaluated. SBSC and Giza snails showed greater susceptibilities to infection and lower mortality rates. In addition, at 6 and 72 h post-exposure to miracidia all the snail groups showed no difference in the anatomical locations of sporocysts. The larvae were found in the head-foot, the mantle collar and the tentacles of the snails. Sporocysts showed normal development with low tissue reactions in SBSC and Giza snail groups infected with S. mansoni miracidia (SBSC). However, in Fayoum, Kafr El-Sheikh, Ismailia and Damietta snail groups, variable tissue responses were observed in which numerous hemocytes made direct contact with S. mansoni larvae forming capsules. The results suggested that, different responses of B. alexandrina snail's hemocytes towards S. mansoni are related to the degree of susceptibility of these snails. So this is important in planning the strategy of schistosomiasis control.
The Compatibility Between Biomphalaria glabrata Snails and Schistosoma mansoni
Elsevier eBooks, 2017
This review reexamines the results obtained in recent decades regarding the compatibility polymorphism between the snail, Biomphalaria glabrata, and the pathogen, Schistosoma mansoni, which is one of the agents responsible for human schistosomiasis. Some results point to the snail's resistance as explaining the incompatibility, while others support a "matching hypothesis" between the snail's immune receptors and the schistosome's antigens. We propose here that the two hypotheses are not exclusive, and that the compatible/incompatible status of a particular host/parasite couple probably reflects the balance of multiple molecular determinants that support one hypothesis or the other. Because these genes are involved in a coevolutionary arms race, we also propose that the underlying mechanisms can vary. Finally, some recent results show that environmental factors could influence compatibility. Together, these results make the compatibility between B. glabrata and S. mansoni an increasingly complex puzzle. We need to develop more integrative approaches in order to find targets that could potentially be manipulated to control the transmission of schistosomiasis. 2 THE GENETIC DETERMINISM OF THE COMPATIBILITY/INCOMPATIBILITY OF BIOMPHALARIA GLABRATA AND SCHISTOSOMA MANSONI The low prevalence of snails with patent schistosome infection, which is usually observed in transmission foci (Anderson and May 1979; Sire et al., 1999), was first believed to be explained by the low probability of an encounter between the partners. This hypothesis cannot be excluded in the interaction between B. glabrata and S. mansoni. However, a molecular screening approach yielded interesting results regarding the interaction between Schistosoma haematobium and Bulinus globosus snails. This work showed that although patency was often very low (less than 4% shed cercariae), more than 40% of the snails were exposed to the parasite in the field (Allan et al., 2013). Thus, snails experienced high levels of parasitic exposure, but only a small proportion of infected snails reached the stage of cercarial shedding. Moreover, even if snails were penetrated by miracidia, the infections often failed to develop to patency (Allan et al., 2013). These results suggest that nonsusceptibility or incompatibility of a particular host and parasite combination is a major factor in the low prevalence observed in the field. This nonsusceptibility/incompatibility can also reflect a biochemically unfavourable intramolluscan environment for the parasite, which is termed "unsuitability" (Lie and Heyneman, 1977; Sullivan and Richards, 1981). However, the most frequently involved mechanism consists of the recognition, encapsulation and killing of the parasite by immune cells (haemocytes) of the snail (Fig. 1 A). Numerous infection-based experiments have been performed
2016
Schistosomiasis, the most important parasitic disease in Egypt, has plagued its people since ancient times. Two species of Biomphalaria are reported from Egypt, the indigenous Biomphalaria alexandrina and Biomphalaria glabrata, the latter is believed to be introduced during the past few decades. Both are known to be excellent hosts of Schistosoma mansoni, in Egypt. SDS-PAGE was used to separate tissue proteins of control and Schistosoma-infected Biomphalaria alexandrina and B.glabrata snails. Also total protein of these groups was measured using Bradford assay method. The present data showed that there is a variation in the protein profiles under the effect of infection, and the days of infections can also affect total and protein profiles pattern. There was a significant decrease in B.alexandrina total protein, in contrary, total protein of B.glabrata groups exhibited significant and insignificant increase under the effect of infection. The electrophoretic pattern showed that there...
Schistosomiasis remains a disease of major global public health concern since it is a chronic and debilitating illness. The widely distributed Schistosoma mansoni that causes intestinal schistosomiasis represents a great threat. Its worldwide distribution is permitted by the broad geographic range of the susceptible species of its intermediate host, Biomphalaria, which serves as an obligatory host for the larval stage, at which humans get infected. The objectives were to identify the proteins responsible for the snails' compatibility outcome through differentiation between the total proteins among Biomphalaria alexandrina snails at different ages. The work was conducted on snails that differ in age and genetic backgrounds. Four subgroups (F1) from the progeny of self-reproduced susceptible and resistant snails (F0) were studied. Infection rates of these subgroups (young susceptible, adult susceptible, young resistant and adult resistant) were 90 %, 75 %, 40 % and 0 %, respectively. Using Sodium Dodecyl Sulphate Polyacrylamide Gel electrophoresis (SDS-PAGE), differences in protein expression were evaluated between adult and young snails of different subgroups. Dice similarity coefficient was calculated to determine the percentage of band sharing among the experimental subgroups. The results showed that the combination of similarities between age and compatibility status of the snails, lead to the highest similarity coefficient, followed by the combination of similarities of both genetic origin and age, even though they differ in the compatibility status. On the other hand, the differences in the genetic background, age and compatibility status, lead to the least similarity index. It was also found that the genetic background in young snails plays a major role in the determination of their compatibility, while the internal defense system has the upper hand in determining the level of adult compatibility. In conclusion, the findings of the present work highlight the great impact of the snail age in concomitance with the genetics and the internal defense in the determination of B. alexandrina/S.mansoni compatibility. Future works are recommended, as further characterization of the shared protein bands among the studied subgroups is needed to clarify their role in host-parasite relationship. Rev. Biol. Trop. 64 (4): 1747-1757. Epub 2016 December 01.