Measurement of mitochondrial respiration in permeabilized fish gills

Abstract

Physiological investigations of fish gills have traditionally centred on the two principal functions of the gills: gas exchange and ion regulation. Mitochondrion-rich cells (MRCs) are primarily found within the gill filaments of fish, and are thought to proliferate in order to increase the ionoregulatory capacity of the gill in response to environmentally induced osmotic challenges. However, surprisingly little attention has been paid to the metabolic function of mitochondria within fish gills. Here, we describe and validate a simple protocol for the permeabilization of fish gills and subsequent measurement of mitochondrial respiration rates in vitro. Our protocol requires only small tissue samples (8 mg), exploits the natural structure of fish gills, does not require mechanical separation of the gill tissue (so is relatively quick to perform), and yields accurate and highly reproducible measurements of respiration rates. It offers great potential for the study of mitochondrial function in gills over a wide range of fish sizes and species.

Adipose tissue mitochondrial respiration in Atlantic salmon: implications for sex-dependent life-history variation

“…Salin et al, 2016), but this was an expected outcome since adipose tissue is mostly composed of lipids (Nanton et al, 2007). Despite the lower rate of mitochondrial respiration in adipose tissue, the L/P ratio indicated that approximately 30% of mitochondrial respiration was related to proton leak, which is similar to the levels reported previously in fish intestine (Brijs et al, 2017), but higher than that reported in gill (Dawson, Millet, Selman, & Metcalfe, 2020), or muscle and liver (Salin, Auer, Anderson, Selman, & Metcalfe, 2016), though it should be noted that the protocols used in measuring Leak respiration often differ between studies. As expected, CI&CII-linked respiratory leak through the entire electron transport chain (Leak Omy) was higher than CI-linked respiratory leak (Leak CI) in our study.…”

Cellular oxygen consumption, ROS production and ROS defense in two different size-classes of an Amazonian obligate air-breathing fish (Arapaima gigas)

“…This is in line with our measurements of Na + /K + -ATPase activity and also of V-ATPase activity in gill tissue and ABO, which revealed that the activity of both ATPases compared to activities recorded in water breathing fish or even the air-breathing Hoplerythrinus unitaeniatus are particularly low, pointing to a low ion exchange capacity of A. gigas gills, in small as well as in larger fish [8,27]. In accordance, the gills' oxygen uptake of A. gigas is lower compared to the water-breathing brown trout (Salmo trutta) [28]. Interestingly, the RCR of gills of larger fish is greater than that of small fish.…”

“…In accordance, the gills' oxygen uptake of A . gigas is lower compared to the water-breathing brown trout ( Salmo trutta ) [ 28 ]. Interestingly, the RCR of gills of larger fish is greater than that of small fish.…”

Climate change‐induced deprivation of dietary essential fatty acids can reduce growth and mitochondrial efficiency of wild juvenile salmon

“…This article is protected by copyright. All rights reserved respiration protocols to determine LEAK (Ln) and respiratory control ratio (RCR) were adapted from Dawson, Millet et al (2020), for details see ESM 3.…”

“…Respiration rate was measured as the rate of decline in O 2 concentration. Mitochondrial respiration protocols to determine LEAK (Ln) and respiratory control ratio (RCR) were adapted from Dawson, Millet, et al (2020), for details see ESM 3.…”