Do fathead minnows, Pimephales promelas Rafinesque, alter their club cell investment in responses to variable risk of infection from Saprolegnia?

Abstract

Fish in the Superorder Ostariophysi possess large epidermal club cells that release chemical cues warning nearby conspecifics of danger. Despite the long-held assumption that such club cells evolved under the selective force of predation, recent studies demonstrated that predation has no effect on club cell investment. Rather, club cells have an immune function and cell production may be stimulated by skin-penetrating pathogens and parasites. The current work investigates whether fathead minnows, Pimephales promelas, alter their club cell characteristics based on variation in infection risk. In a 2 × 3 design, we exposed minnows to infective cysts of two oomycete species (Saprolegnia ferax and S. parasitica) at three different concentrations (2, 20 or 200 cysts L(-1)). Club cell characteristics (number and size) were quantified 12 days after exposure. Saprolegnia parasitica is thought to be more pathogenic than S. ferax, hence we predicted greater club cell investment and a larger turnover rate of cells by minnows exposed to S. parasitica than S. ferax. We also predicted that minnows exposed to higher numbers of cysts should invest more in club cells and have a higher turnover rate of cells. We found no difference in club cell density or size between fish exposed to the two Saprolegnia species; however, fish exposed to high concentrations of pathogens had smaller club cells than those exposed to low concentrations, indicating a higher rate of turnover of cells in the epidermis.

Histology and morphometry of the skin of purple spaghetti-eel Moringua raitaborua (Anguilliformes, Moringuidae)

“…Such physiologies are well-supported by the ED with SPCs, CCs, MCs, and SCCs con rmed in this study. Among them, two unicellular secretary glands, CCs and MCs, not only produce alarm-clue chemicals (proteins and pheromones such as serotonin and 5-HT) with cytoplasmic membrane breakage for antipredator response in conspeci cs (Zaccone et al, 1990;Carreau-Green et al, 2008;Manek et al, 2013) but also engage in defense against pathogens that can penetrate the skin (Pollock, 2011) and repair damaged tissues with chondroitin and keratin (Damasceno et al, 2012). They can help oxygen penetrate deeper toward the dermal matrix of connective tissue due an abundance of water and acidophilic proteins of a positive ion (Jakubowski, 1958;Mittal and Munshi, 1971;Park, 2002).…”

Histology and morphometry of the skin of purple spaghetti-eel Moringua raitaborua (Anguilliformes, Moringuidae)

“…Such physiologies are well-supported by the ED with SPCs, CCs, MCs, and SCCs confirmed in this study. Among them, two unicellular secretary glands, CCs and MCs, not only produce alarm-clue chemicals (proteins and pheromones such as serotonin and 5-HT) with cytoplasmic membrane breakage for antipredator response in conspecifics (Zaccone et al 1990 ; Carreau-Green et al 2008 ; Manek et al 2013 ) but also engage in defense against pathogens that can penetrate the skin (Pollock 2011 ) and repair damaged tissues with chondroitin and keratin (Damasceno et al 2012 ). They can help oxygen penetrate deeper toward the dermal matrix of connective tissue due an abundance of water and acidophilic proteins of a positive ion (Jakubowski 1958 ; Mittal and Munshi 1971 ; Park 2002 ).…”