Variations in the presence of chloride cells in the gills of lampreys (Petromyzontiformes) and their evolutionary implications

Abstract

Although confined to fresh water, non-parasitic species of lampreys and the landlocked parasitic sea lamprey, all of which were derived relatively recently from an adromous ancestors, still develop chloride cells, whose function in their ancestors was for osmoregulation in marine waters during the adult parasitic phase. In contrast, such cells are not developed by the non-parasitic least brook lamprey Lampetra aepyptera, which has been separated from its ancestor for >2 million years, nor by the freshwater parasitic species of the genus Ichthyomyzon. The length of time that a non-parasitic species or landlocked parasitic form or species has spent in fresh water is thus considered the overriding factor determining whether chloride cells are developed by those lampreys.

Mechanisms of acclimation to chronic intermittent hypoxia in the gills of Largemouth bass (Micropterus salmoides)

“…Glycolysis not only produces ATP but also generates pyruvate, which can enter the mitochondria and produce more ATP (Knox et al, 1980). Interestingly, our study revealed the presence of several elongated megamitochondria in the gills, in addition to numerous smallsized mitochondria that have been reported in previous studies (Bartels et al, 2015;Wilson and Laurent, 2002). The formation of megamitochondria may be an adaptive process of the organism in response to unfavorable environments at the intracellular organelle level (Wakabayashi, 2002).…”

Claudins of sea lamprey (Petromyzon marinus) – organ‐specific expression and transcriptional responses to water of varying ion content

“…On the contrary, juvenile sea lamprey are euryhaline and maintain salt and water balance within tight limits whether they are in FW, brackish water or SW (Bartels & Potter, 2004;Peek & Youson, 1979;Zydlewski & Wilkie, 2013). In this regard, plasticity of lamprey epithelia, and specifically of the gill epithelium, has been studied for more than 50 years (Bartels et al, 1996;Bartels et al, 2011;Bartels et al, 2012;Bartels et al, 2015;Bartels & Potter, 1991;Bartels & Potter, 1993;Hardisty, 1956;Mallatt et al, 1995;Peek & Youson, 1979), and changes in the architecture of the TJ complex in this organ that are life-stage dependent, or that take place in response to changed environmental ion levels, are well documented (Bartels & Potter, 1991;Bartels & Potter, 1993;Bartels & Potter, 2004). Therefore, it is logical to hypothesize that the molecular physiology of the sea lamprey TJ complex (and its protein complement) plays an important role in the osmoregulation of sea lamprey.…”