**9. Pollutant-induced apoptosis and necrosis of invertebrate immunocytes**

Apoptosis, the programmed cell death, is functionally involved in developmental and immunological processes of organisms. Moreover, apoptosis helps in the process of removal of damaged cells and thus is considered an important machinery of survival of host animal in polluted environment. It is involved in specific cell signaling mechanism, which is yet to be studied in invertebrates in detail. However, pesticides and other environmental xenobiotics are reported to affect the apoptotic and necrotic pathways of the immunoactive cells of invertebrates (Figure 7). Current scientific reports suggest apoptosis as an effective biomarker of aquatic pollution. Apoptosis presented changes in the morphological characteristics of cells including membrane blebbing, nuclear condensation, cytoplasmic shrinkage and membrane asymmetry. Kiss (2010) reported the translocation of phosphatidylserine from inner leaflet of the plasma membrane to the outer leaftet, which was considered a hallmark of apoptosis [38]. Ray et al. (2013b) reported the apoptotic and necrotic cell deaths of haemocytes of *B. benga‐ lensis* and *L. marginalis* under the sublethal exposures of cypermethrin and fenvalerate, respectively, employing flow cytometry [2]. According to them, cypermethrin and fenvalerate treatment yielded decrease in the percentage of apoptotic and necrotic haemocyte morpho‐ types of *B. bengalensis* and *L. marginalis.* Pyrethroid-induced apoptosis of molluscan haemo‐ cytes is considered as impairment of immunological status of *B. bengalensis* and *L. marginalis.*

Figure 7: Immunofluorescent detection of apoptosis exposed to sublethal (3000 ppm/ 7 days) concentrations of washing soda. (a) and represent positive staining by Annexin V of hemocytes of pond snail, V-FITC and propidium iodide respectively, (c) pond B. bengalensis FITC **Figure 7.** Immunofluorescent detection of apoptosis of haemocytes of pond snail, *B. bengalensis* exposed to sublethal (3000 ppm/7 days) concentrations of washing soda. (a) and (b) represent positive staining by Annexin V-FITC and pro‐ pidium iodide, respectively; (c) depicts co-localization of fluorescent signals.

and (b)

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