Characterisation of cholinesterases in mucous secretions and their localisation in epidermis of Labeo rohita and Cirrhinus mrigala
Cholinesterases are multifunctional enzymes and have been associated with diverse physiological functions in addition to their classical role at synapses. In the present study, cholinesterase (ChE) isozymes have been characterised in mucous secretions and their activity has been localised in the epidermis of Labeo rohita and Cirrhinus mrigala. Zymography using specific substrates and inhibitors revealed the presence of two ChE isozymes—ChE-1 and ChE-2. The isozyme ChE-1 was characterised as an atypical butyrylcholinesterase and ChE-2 as a typical acetylcholinesterase in skin mucous secretions of both the fish species. Enzyme histochemical analysis demonstrated the presence of ChE activity in the epidermis of the fish species investigated. In both the fish species, strong ChE activity was observed in the outer-layer epithelial cells, taste buds and neuromasts. The middle and basal layer epithelial cells showed moderate to weak ChE activity. Club cells and mucous goblet cells showed the absence of ChE activity. Characterisation with specific inhibitors indicates that acetylcholinesterase (AChE) was the major cholinesterase type expressed in the epidermis of the two fish species investigated. Immunohistochemical localisation of apoptotic and cell proliferation markers, in addition, revealed high expression of active caspase 3 in the outer-layer epithelial cells, and proliferating cell nuclear antigen (PCNA) in the middle and basal layer epithelial cells. High ChE activity in caspase 3-positive cells in the outer layer of the epidermis and low in PCNA-positive cells in middle and basal layers could point towards the possible involvement of ChEs in cell death and their final extrusion from skin surface.
KeywordsFish Epidermis Mucus Epithelial cells, Cholinesterases Apoptosis
Mr. Ashwini Kumar Nigam was supported as Research Associate from Council of Scientific and Industrial Research (CSIR) [Scheme No. 9/13 (660)/2017-EMR-I], Government of India. Mr. Neeraj Verma was supported by CAS-JRF and CAS-SRF under scheme CAS-Merged R-A/c grant, Award No. 14740 (Banaras Hindu University). Mr. Ayan Srivastava was supported by Banaras Hindu University Fellowship (Scheme No. 5012) sponsored by the University Grants Commission, Government of India. We hereby declare that the experiments comply with the current laws of the country (India) in which they were performed.
Compliance with ethical standards
All experiments were conducted in accordance with the ethical guidelines related to treatment and maintenance of animals.
- APHA, AWWA, WPCF (1985) Standard methods for the examination of water and waste water. American Public Health Association, WashingtonGoogle Scholar
- Assis CRD, Bezerra RS, Carvalho LB Jr (2011) Fish cholinesterases as biomarkers of organophosphorus and carbamate pesticides. In: Stoytcheva M (ed) Pesticides in the modern world-pests control and pesticides exposure and toxicity assessment. InTech, Rijeka, pp 253–278Google Scholar
- Bancroft JD (2002) Enzyme histochemistry and its diagnostic applications. In: Bancroft JD, Gamble M (eds) Theory and practice of histological techniques, 5th edn. Churchill Livingstone, New York, pp 593–620Google Scholar
- Bancroft JD, Gamble M (2002) Theory and practice of histological techniques, 5th edn. Churchill Livingstone, New YorkGoogle Scholar
- Çokuğraş AN (2003) Butyrylcholinesterase: structure and physiological importance. Turk J Biochem 28:54–61Google Scholar
- Ehrlich P (1886) Hematoxylinlosung. Z wiss Mikroskop 3:150Google Scholar
- Habig C, Di Giulio RT (1991) Biochemical characteristics of cholinesterases in aquatic organisms. In: Mineau P (ed) Cholinesterase-inhibiting insecticides: their impact on wildlife and the environment. Elsevier, Amsterdam, pp 20–30Google Scholar
- Jin QH, He HY, Shi YF, Lu H, Zhang XJ (2004) Overexpression of acetylcholinesterase inhibited cell proliferation and promoted apoptosis in NRK cells. Acta Pharmacol Sin 25:1013–1021Google Scholar
- Monroe JD, Rajadinakaran G, Smith ME (2015) Sensory hair cell death and regeneration in fishes. Front Cell Neurosci 9(Article 131):1–18Google Scholar
- Silver A (1974) The biology of cholinesterases. North Holland Pub Co, AmsterdamGoogle Scholar
- Soreq H, Zakut H (1993) Human cholinesterases and anticholinesterases. Academic Press, San DiegoGoogle Scholar
- Teraki Y, Shiohara T (1999) Apoptosis and the skin. Eur J Dermatol 9:41325Google Scholar
- Thompson H, Walker C (1992) Blood esterases as indicators of exposure to organophosphorus and carbamate insecticides. In: Fossi MC, Leonzio C (eds) Nondestructive biomarkers in vertebrates. Lewis Publishers, Boca Raton, pp 37–62Google Scholar
- Walker CH, Thompson HM (1991) Phylogenetic distribution of cholinesterases and related esterases. In: Mineau P (ed) Cholinesterase inhibiting insecticides: their impact on wildlife and the environment. Elsevier, Amsterdam, pp 3–19Google Scholar