Histopathological changes in gills of the estuarine crab Chasmagnathus granulata (Crustacea-Decapoda) following acute exposure to ammonia

Dept. Ciências Fisiologicas, Lab. Zoofisiologia, Fundação Universidade Federal do Rio Grande, CP 474, Rio Grande, RS, 91206-900, Brazil.
Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology (Impact Factor: 2.3). 02/2000; 125(2):157-64. DOI: 10.1016/S0742-8413(99)00093-6
Source: PubMed


Histopathological effects of ammonia on the gills of the estuarine crab Chasmagnathus granulata (Dana, 1851) were evaluated after acute exposure to ammonia concentrations around LC(50) value (17.85 Mm). Disruption of pilaster cells and a subsequent collapse of gill lamellae were the main effects observed. Epithelial necrosis and hyperplasia were also detected. Significant (P<0.05) increases in pCO(2) and lactate, and significant decreases of pO(2) were detected in the haemolymph of ammonia-exposed crabs. These changes suggest that the observed histopathological damage affected gas exchange, possibly leading to death.

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    • ") and such a process was suggested to contribute to signi¢cantly increasing the haemo - lymph pH of early S . serrata juveniles ( Romano & Zeng 2007d ) . However , in the current study the haemolymph pH of P . pelagicus juveniles remained unaltered throughout the sub - lethal ammonia - N ex - posure or lethal ammonia - N levels causing morbidity . Rebelo et al . ( 2000 ) detected a similar result with N . granulata juveniles and suggested a compensatory ef - fect occurred as a result of increasing haemolymph CO 2 ( leading to a haemolymph pH decrease ) match - ing with haemolymph NH 3 protonation ( leading to a haemolymph pH increase ) . Obviously , further experi - mentation is warranted to determine"
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    • "A reduction in haemolymph pH levels may be accomplished by the significantly reduced haemolymph Ca 2+ levels (Taylor and Whiteley, 1989; Rebelo et al., 1999), increased exchange of haemolymph HCO 3 − outwards via apically located Cl − /HCO 3 − transport (Henry and Wheatly, 1992) which may explain the unaltered haemolymph osmolality and/or haemolymph CO 2 accumulation (Varley and Greenaway, 1992). The latter can be caused by ammonia-N induced anterior gill damage, including epithelial thickening and lamellae collapse, as observed in C. granulata adults (Rebelo et al., 2000) and P. pelagicus early juveniles (Romano and Zeng, 2007). Further investigation is warranted to determine the exact cause(s). "
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    ABSTRACT: The current study was conducted to determine the LC(50) value of ammonia-N as well as the effects of acute exposure to elevated ammonia on the haemolymph osmolality, ionic composition, ammonia-N and pH levels of early juvenile mud crabs, Scylla serrata. The results show that early S. serrata juveniles have a high 96-h LC(50) value of 95.35 mg/L ammonia-N (6.81 mg/L NH(3)-N) or 6.80 mmol/L total ammonia-N (0.486 mmol/L NH(3)-N). Following a 96-h exposure, the haemolymph osmolality and K(+) levels of the surviving crabs remained unaltered (p>0.05) at all ammonia-N concentrations, while the haemolymph Na(+) and Ca(2+) were significantly lower (p<0.05) for the crabs exposed to 5.710 and 7.138 mmol/L ammonia-N. While the haemolymph ammonia-N levels of the crabs significantly increased (p<0.01) with increasing external ammonia-N concentrations, the haemolymph ammonia-N of the crabs remained below the external ammonia-N concentrations. The haemolymph pH of the crabs significantly increased between 0.714 and 4.283 mmol/L total ammonia-N. However, at 5.710 mmol/L total ammonia-N the haemolymph pH dropped and was not significantly different (p>0.05) from that of the control crabs which coincided with significantly lower (p<0.05) haemolymph Na(+) and Ca(2+) levels. These physiological responses may explain the high ammonia tolerance of early S. serrata juveniles.
    Comparative Biochemistry and Physiology - Part A Molecular & Integrative Physiology 11/2007; 148(2):278-85. DOI:10.1016/j.cbpa.2007.04.018 · 1.97 Impact Factor
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    • "The process involving Na + K + ATPase activity involves the exchange of sodium from the water for ammonia in the fish (Salama et al., 1999; Shrimpton and McCormick, 1999). In fish, branchial gas exchange and oxidative metabolism are disturbed by excess ammonia causing gill damage, excessive mucus production (Smart, 1976; Wilkie, 1997) or osmoregulation imbalance (Rebelo et al., 2000; Lease et al., 2003). This experiment was designed to determine whether ammonia in the external environment could alter the rate of activity of Na + K + ATPase and associated metabolic enzymes at the gill level. "
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