Heavy metals and hydrocarbons are of the most common marine pollutants around the world. The present study aimed to assess the concentration of petroleum hydrocarbons and heavy metals in tissues of the snail cyclope neritea, water and sediments from two sites of the study area (Temsah lake and Suez canal) represent polluted and unpolluted sites respectively. The results showed that, the levels of the heavy metals (Pb, Cd, Co, Mg and Zn) in the polluted area have reached harmful limits recorded globally. Lead in water, sediment and tissue of the snail reached to 0.95 ppm, 4.54 ppm and 7.93 ppm respectively. Cadmium reached 0.31 ppm, 1.15 ppm and 3.08 ppm in the corresponding samples. Cobalt was not detected in water, but it reached 1.42 ppm and 10.36 ppm in the sediment and snails tissue respectively. Magnesium in water, sediment and tissue of the snail reached 3.73 ppm, 9.44 ppm and12.6 ppm respectively. Zinc reached 0.11 ppm, 3.89 ppm and 12.60ppm in the corresponding samples. Meanwhile, hydrocarbons in the polluted area (site1) reached 110.10 μg/L, 980.15 μg/g and 228.00 μg/g in water sediment and digestive gland tissues of the snails respectively. Whereas, hydrocarbons in the unpolluted area (site2) were estimated as 14.20 μg/L, 55.60 μg/g and 22.66 μg/g in water, sediment and tissue of the snails respectively.The combination of histopathological image with monitoring of the metal level in the digestive gland of the present snail provides an important tool for early detection of impending environmental problems and potential public health issues. Petroleum hydrocarbons are toxic to the marine fauna when present above certain limit in the marine water. The major detoxification organ in molluscs is the digestive gland, which has been used as a bioindicator organ for toxicity assessment. The effect of high crude oil on the digestive gland tubules of exposed snails when examined microscopically reveals a series of histological changes which indicates that the cellular compensatory mechanism is activated by hydrocarbons. These changes include vacuolation and presence of pyknotic nuclei.
Laboratory studies have been carried out on the toxic effects of three different pesticides namely, Diazinon, Lambdacyhalothrin and Methomyl as poisonous baits against the land snail, Monacha cantiana. The activities of five vital tissue enzymes, as Catalase (CAT), Malondialdehyde (MDA), Aspartate transaminase (AST). Alanine transaminase(ALT) and Alkaline phosphatase (ALP) were examined after exposure of these snails to LC 50 (5ppm) of the tested pesticides for 96hr. Results showed clearly that all sublethal concentrations of tested pesticides lead to a significant increase in the activities of the enzymatic levels within tissues of treated snails. On the other hand, LC 25 (2.5 ppm) of Diazinon was found to produce severe histopathological alterations in the hermaphrodite gland of M. cantiana, including, deterioration in germinal epithelium of the acini spermatocytes as well as reduction in numbers of sperms which are inhibited to develop to the late stages of maturity.
Schistosomiasis is caused by blood flukes including all Schistosoma species. It affects about 207 million persons in 76 countries across the world, and is more prevalent in developing countries where about 800 million people are at the risk of schistosomiasis [1]. Following oviposition, schistosomes eggs that failed to exit with either urine or stools are carried back into the liver to be lodged in the pre-sinusoidal capillaries. The eggs are in intimate contact with the capillary endothelium before and during the generation of the granulomatous response [2]. Schistosoma miracidium inside the ovum secretes glycoprotein antigens that pass through microscopic pores within the egg shell, so are called SEA. These antigens elicit a vigorous immune response that encapsulates the ova in pre-granuloma collagen fibers and immune cells, predominantly eosinophils and macrophages. The granuloma formation presents a barrier to sequester egg toxicity and antigenicity. Fibrosis of granulation tissues leads to disturbance of hepatic parenchymal architecture including its vasculature [3]. Despite portal vascular impairment, it was found that the total hepatic blood flow remained within normal limits with normal parenchymal cell perfusion, accompanied by absent gross changes in hepatic function tests. This was attributed to hepatic neovascular formation in the
Albendazole and Nitazode were tested as molluscicidal agents against Biomphalaria alexandrina snails. The effect of Albendazole and Nitazode on snails infected with Schistosoma mansoni miracidia and hermaphrodite glands of Biomphalaria alexandrina snails were also carried out. In addition, the parasitological parameters, the dynamics of serum-specific immunoglobulins and splenic cytokines associated with changes in granuloma diameter were assessed. The results indicate that exposure of B. alexandrina to Albendazole and Nitazode, resulted in a considerable reduction in the infectivity of S. mansoni miracidia to the snails and a severe damage in the hermaphrodite gland cells of treated snails. In addition, immunization did not affect worm reduction, but a slight decrease in granuloma diameter, increase in immunoglobulins and cytokines was observed. Reduction in worm burden was associated with a reduction in ova count. Changes in oogram pattern were mainly due to Albendazole and Nitazode. In conclusion, treatment with Albendazole and Nitazode with immunization resulted in significant reduction of parasitological parameters and rise of specific immunoglobulins.
The present study was designed to investigate histochemically the detection of carbohydrate and protein in the normally feeding snails and after 15 and 30 days of starvation. Generally, abundant carbohydrate and protein materials were detected in the component cells of the digestive gland of normally feeding snails. The results of this investigation revealed a pronounced decline of carbohydrates in the digestive gland cells of Monacha cartusiana snails after starvation. Severe decline in carbohydrate content was observed especially after 30 days of starvation. Moreover, protein inclusions have exhibited a week stainability in the digestive gland cells of these snails as a consequence of starvation.
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