Reference no: EM133669301

Question: Do you agree or disagree with their interpretation of the results? Why? The kidneys are one of the major osmoregulatory organs in fishes (Engelund & Madsen, 2011) as well as in amphibians (Hillyard, 1999). Amphibians represent the crucial evolutionary link between water-dwelling fish and land-dwelling animals. Thus, it is important to compare the biological role and adaptability of kidney cells during osmotic stress between fishes and amphibians. To mimic the natural setting of varying osmolarity in vitro, we measured a range of different osmotic stimulations from 50 to 700 mOsm and different periods of stimulation from 6 to 24 h on fish CIK cells (unpublished data). We found that CIK cells were able to tolerate to some extend lower salinities (100 mOsm) and higher salinity (700 mOsm) during short periods, but present visible morphological changes after 16 h of exposure to the two environments. In contrast, amphibian GSK cells became extremely unhealthy suggesting that CIK rather than GSK cells have a higher capacity to tolerate hyperosmolality. Research on amphibian osmoregulation has mainly focused on frogs. It was found that the osmotic pressure of the excreted urine was always slightly lower than that of the body fluids, which explains why frogs in hyperosmotic solutions cannot establish normal water balance (Jorgensen, 1997). This may explain why kidney cells of the Chinese giant salamander were more sensitive to hyperosmotic challenge when compared to fish. In adult frogs, gut, kidney, urinary bladder and skin are important in osmoregulation organs. For example, skin can adapt to changes in water permeability, and it is important for the maintenance of a constant osmotic pressure (Mori et al., 2012). Due to changes between dehydration on land and rehydration in the water, the osmoregulatory capacity of the Chinese giant salamander is mainly regulated by skin and kidney. However, little was previously known about the osmoregulation of the Chinese giant salamander and the nature of the integrated mechanisms are still not well understood. Further research on other cell types of the Chinese giant salamander will provide new insights on the relationships between osmotic stress and cell responses in amphibians. The Chinese giant salamander is an expensive delicacy and farming is rapidly growing in China in recent years (Cunningham et al., 2016). A better understanding of the mechanism of osmotic regulation may provide essential data for artificial breeding.