Quantification of heat shock protein 70 and acetylcholinesterase over a time course suggests environmental adaptation in a foundational molluscan species

Abstract

Waterways in urban areas often act as repositories for sewage, industrial waste, and environmental contaminants. In response, inhabitants of these watersheds undergo physiological adaptations specific to their respective environments. Effects of these stressors can be assayed by quantification of various well-documented biomarkers in sentinel species such as the Atlantic Ribbed mussel, Geukensia demissa, a native to the Bronx River Estuary, Bronx, NY, USA. Heat shock protein 70 (Hsp70) is a universally expressed biomarker for an array of environmental stressors including toxins and low dissolved oxygen. To better understand the mechanisms by which organisms tolerate their contaminated environments, we monitored the constitutive and heat shock-induced levels of two proteins: Hsp70 and acetylcholinesterase (AChE) in natural populations of G. demissa from differentially impacted sites: the Bronx River and Greenwich Cove estuaries. We show that G. demissa from the Bronx River exhibits a higher level of constitutive Hsp70, and launches a more rapid and robust heat shock response than does its Greenwich Cove counterpart. In addition, AChE levels are recovered more quickly in Bronx River mussels. Based on response pattern investigations from heat stress as well as constitutive expression, we suggest that the Hsp70/AChE chaperone/client relationship exemplifies the unique adaptive mechanisms utilized by organisms in order to tolerate environmentally impacted habitats. Results from this study offer important insights from an ecological perspective into the molecular and cellular basis of stress response and provide valuable information regarding adaptation to the increased demands of challenging environments.

Urbanization drives genetic differentiation in physiology and structures the evolution of pace-of-life syndromes in the water flea Daphnia magna

“…Although some studies observed clear phenotypic upregulation of stress physiological parameters (e.g. GST [33]; Hsp70 [34]), evidence for an evolutionary shift in organismal stress physiology in cities is so far limited (but see [8,14]).…”

Divergent epigenetic profiles from two differentially impacted wild populations of estuarine cordgrass (Sporobolus alterniflorus)

“…The National Oceanic and Atmospheric Administration (NOAA) National Estuarine Eutrophication Survey classifies water quality falling between 2 and 5 mg/L dissolved oxygen as stressed (Bricker et al, 1999). These data indicate that organisms residing in the Bronx River estuary are exposed to chronic, low oxygen levels, a condition that induces stress and metabolic dysfunction (Halem, et al, 2014;Ravaschiere et al, 2017). Table 1.…”

“…Human activity, industrialization, and climate change continue to negatively impact estuarine ecosystems, especially in urbanized areas (Limburg et al, 2005; Astaraie-Imani et al, 2012; Chin et al, 2013). Estuarine species face stresses associated with adverse environmental conditions such as low dissolved oxygen, combined sewage overflow, toxin contamination, bank destabilization, habitat degradation, and extreme temperature fluctuation (Van Dolah, et al, 2008; Courrat et al, 2009; Halem et al, 2014; Ravaschiere et al, 2017). Knowledge of the molecular mechanisms underlying stress adaptation is essential if we hope to rehabilitate estuarine ecosystems adversely affected by urbanization.…”

Evolutionary responses of marine organisms to urbanized seascapes

“…In addition, adequate genetic diversity is necessary for evolutionary responses to a wide range of urban stressors. A number of studies of rapid evolution to urban stressors indicate organisms are able to adapt quickly due to standing genetic variation (see Reid et al 2017; Wirgin et al., 2011 below), or even more intriguingly, via introgression from other species (Oziolor et al, 2019). Additional experimental evidence indicates the importance of standing variation in adaptation; for example, Nevo, Noy, Lavie, Beiles, and Muchtar (1986) showed that in several pairs of species with differing levels of genetic diversity, the species with greater diversity was found to be more resistant to toxicants.…”