EFFECT OF CU, ZN, CD AND HG ON THE HISTOLOGY OF THE DlGESTIVE GLAND OF THE FRESHWATER SNAIL BIOMPHALARIA ALEXANDRINA AND BULINUS TRUNCATUS

1999 ◽  
Vol 3 (1) ◽  
pp. 39-57
Author(s):  
ToIba A ◽  
Bedir M. ◽  
Mossa M.
2013 ◽  
Vol 88 (4) ◽  
pp. 411-416 ◽  
Author(s):  
O.M.S. Mostafa ◽  
A.-T.H. Mossa ◽  
H.M.A. El Einin

AbstractIn spite of using aquatic snails as bioindicators for water pollution, little attention has been paid to the effect of parasitism upon the concentration of heavy metals (Al, Cd, Cu, Fe, Mn, Pb and Zn) in these organisms. The present study therefore aimed to compare the concentrations of heavy metals in trematode-infected Biomphalaria alexandrina collected from Kafer Alsheikh and Menofia provinces, Egypt, with uninfected snails from the same sites, in order to assess the effect of parasitism on the use of these snails as bioindicators. The concentrations of heavy metals in the soft parts and shells of snails were measured by flame atomic absorption spectrometry. The results showed that the heavy metal profile in snails infected with Echinostoma liei was very different from that in snails infected with Schistosoma mansoni. The total concentration of heavy metals in E. liei-infected snails collected from Kafer Alsheikh or Menofia province was greater than in uninfected snails. In contrast, the total concentration of heavy metals in S. mansoni-infected snails was reduced compared with uninfected snails. In conclusion, the status of snails with respect to parasitic infection must be taken into consideration when these snails are used as bioindicators.


2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Marian Elias ◽  
Rasha S. Hanafi ◽  
Samia El-Bardicy ◽  
Ebtisam A. Hafez ◽  
Rashika El Ridi

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 biochemical techniques and palmitic, oleic, linoleic, and arachidonic acid, assayed by ultraperformance liquid chromatography-tandem mass spectrometry. Successful schistosome infection of B. alexandrina and B. truncatus consistently and reproducibly correlated with snails showing highly significant (up to P < 0.0001 ) decrease in soft tissue and hemolymph content of the monounsaturated fatty acid, oleic acid, and the polyunsaturated fatty acids, linoleic, and arachidonic acids as compared to naïve snails. Snails that resisted twice infection had soft tissue content of oleic, linoleic, and arachidonic acid similar to naïve counterparts. High levels of soft tissue and hemolymph oleic, linoleic, and arachidonic acid content appear to interfere with schistosome development in snails. Diet manipulation directed to eliciting excessive increase of polyunsaturated fatty acids in snails may protect them from infection and interrupt disease transmission in a simple and effective manner.


1993 ◽  
Vol 62 (2) ◽  
pp. 89-100 ◽  
Author(s):  
Flobert Njiokou ◽  
Christian Bellec ◽  
Patrick Berrebi ◽  
Bernard Delay ◽  
Philippe Jarne

SummaryBulinus truncatus, one of the intermediate hosts of the genus Schistosoma is an hermaphrodite freshwater snail species occupying a variety of environments over almost all Africa. These environments are subjected to large variations in water availability. B. truncatus is allotetraploid and its populations exhibit various frequencies of aphallic individuals (unable to reproduce as male). Both traits probably favour a reproduction by self-fertilization. Here we investigate the genetic structure of populations of B. truncatus of Niger and Ivory Coast using protein electrophoresis to analyse the influence of the environment and of both the last traits. To obtain an estimate of the true heterozygosity in this allotetraploid species, we analyse independently the two diploid loci at each tetraploid locus. Our study indicates (i) an extremely low intrapopulation polymorphism with most alleles fixed and the total absence of heterozygotes and (ii) low differentiation between populations. These results indicate high gene flow between populations. However, the existence of private alleles sometimes at high frequency, the low polymorphism and the lack of heterozygotes point to the role of both genetic drift and self-fertilization, the second amplifying the genetic consequences of the first.


Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 973-982
Author(s):  
Frédérique Viard ◽  
Fabienne Justy ◽  
Philippe Jarne

We analyzed short-term forces acting on the genetics of subdivided populations based on a temporal survey of the microsatellite variability in the hermaphrodite freshwater snail Bulinus truncatus. This species inhabits temporary habitats, has a short generation time and exhibits variable rates of selfing. We studied the variability over three sampling dates in 12 Sahelian populations (1161 individuals). Classical genetic parameters (estimators of Ho, He, f selfing rate and Fst) showed limited change over time whereas important temporal changes of allelic frequencies were detected for 10 of the ponds studied. These variations are not easily explained by selection, sampling drift and genetic drift alone and may be due to periodic migration. Indeed the habitats occupied by the populations studied are subject to large temporal fluctuations owing to annual cycles of drought and flood. In such ponds our results support a demographic model of population expansions and contractions under which available habitats, after the rainy season, are colonized by individuals originating from a smaller number of refuges (areas that never dry out in the deepest parts of the ponds). In contrast, selfing appeared to be an important force affecting the genetic structure in permanent ponds.


Genetics ◽  
1996 ◽  
Vol 142 (4) ◽  
pp. 1237-1247 ◽  
Author(s):  
Frédérique Viard ◽  
Philippe Bremond ◽  
Rabiou Labbo ◽  
Fabienne Justy ◽  
Bernard Delay ◽  
...  

Abstract Hermaphrodite tropical freshwater snails provide a good opportunity to study the effects of mating system and genetic drift on population genetic structure because they are self-fertile and they occupy transient patchily distributed habitats (ponds). Up to now the lack of detectable allozyme polymorphism prevented any intrapopulation studies. In this paper, we examine the consequences of selfing and bottlenecks on genetic polymorphism using microsatellite markers in 14 natural populations (under a hierarchical sampling design) of the hermaphrodite freshwater snail Bulinus truncatus. These population genetics data allowed us to discuss the currently available mutation models for microsatellite sequences. Microsatellite markers revealed an unexpectedly high levels of genetic variation with ≤41 alleles for one locus and gene diversity of 0.20–0.75 among populations. The values of any estimator of F  is, indicate high selfing rates in all populations. Linkage disequilibria observed at all loci for some populations may also indicate high levels of inbreeding. The large extent of genetic differentiation measured by F  st, R  st or by a test for homogeneity between genic distributions is explained by both selfing and bottlenecks. Despite a limited gene flow, migration events could be detected when comparing different populations within ponds.


2008 ◽  
Vol 5 (1) ◽  
pp. 84-88
Author(s):  
Baghdad Science Journal

The molluscicidal effects of herbicide 2, 4-D were studied against tow species of freshwater snail Bulinus truncatus and Melanopsis nodosa by short term experiments. Calculated values of lethal concentrations (LC50 and LC100) were maid to two spices for different period of time 24hr, 48hr, 72hr and 96hr. The study had showed that the herbicide 2, 4-D was toxic against the tow species. The toxicity of the herbicide was low or unknown in low concentrations in the first period of exposure 24and 48hr to two spices but it increase gradually with increase period of exposure. The spice of B.truncatus was more tolerant than the M.nodosa. All the individual of M nodosa was death while in B.truncatus the complete death was not appear until finish the period of exposure 96hr.


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