Variations in hepatic biomarkers in American alligators ( Alligator mississippiensis ) from three sites in Florida, USA

Abstract

Sub-individual biomarkers are sub-lethal biological responses commonly used in the assessment of wildlife exposure to environmental contaminants. In this study, we examined the activity of glutathione-s-transferase (GST) and lactate dehydrogenase (LDH), and metallothionein (MT) concentrations among captive-raised alligator hatchlings, wild-caught juveniles, and wild-caught adults. Juveniles and adults were collected from three locations in Florida (USA) with varying degrees of contamination (i.e. Lake Apopka (organochlorine polluted site), Merritt Island National Wildlife Refuge (NWR) (metal polluted site), and Lake Woodruff NWR (reference site)). We examined whether changes in the response of these three biomarkers were age and sex dependent or reflected site-specific variations of environmental contaminants. Juvenile alligators from Merritt Island NWR had higher MT concentrations and lower GST activity compared to those from the other two sites. This outcome was consistent with higher metal pollution at this location. Sexually dimorphic patterns of MT and GST (F > M) were observed in juvenile alligators from all sites, although this pattern was not observed in adults. GST activity was lower in captive-raised alligators from Lake Apopka and Merritt Island NWR as compared to animals from Lake Woodruff NWR, suggesting a possible developmental modulator at these sites. No clear patterns were observed in LDH activity. We concluded that GST and MT demonstrate age and sex specific patterns in the alligators inhabiting these study sites and that the observed variation among sites could be due to differences in contaminant exposure.

Deimination Protein Profiles in Alligator mississippiensis Reveal Plasma and Extracellular Vesicle-Specific Signatures Relating to Immunity, Metabolic Function, and Gene Regulation

“…L-Lactate dehydrogenase was found deiminated in EVs only, and lactate dehydrogenase has previously been identified to be a hepatic biomarker in American alligator (206).…”

Response of phase I and II detoxification enzymes, glutathione, metallothionein and acetylcholine esterase to mercury and dimethoate in signal crayfish (Pacifastacus leniusculus)

“…Ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-deethylase (MROD) and GST activities were measured in hepatopancreas microsomes (EROD and MROD) and cytosol (GST) using previously published protocols with modifications to the procedures (Gunderson et al, 2004; Gunderson et al, 2016). Approximately 0.33g of hepatopancreas was thawed on ice and homogenized in 1 mL of cold homogenization buffer (100 mM Tris, pH 7.4, 0.1 M KCl, 1 mM EDTA, 1mM PMSF, 5 μM aprotinin, 10 μM pepstatin) 10–20 zirconium oxide beads using a Bullet Blender (Next Advance, Inc., BBUC3137) (Speed 7 for 4 min).…”

“…Damage to aquatic ecosystems due to contaminants is a concern and sub-lethal changes in biochemical endpoints in conjunction with contaminant levels can be used to help assess whether exposure causes biological responses in organisms inhabiting impacted habitats (Fernandes et al, 2002; Gunderson et al, 2016). Phase I and II enzyme activities, glutathione (GSH) and metallothionien (MT) concentrations, and acetylcholine esterase (AChE) activities are commonly used biomarkers to assess whether wildlife populations are impacted by contaminants present in the ecosystems in which they live.…”

“…Glutathione S-transferase (GST) is a phase II detoxification enzyme modulated by xenobiotics and thus has been suggested for use as a biomarker indicative of environmental contaminant exposure (Aksu et al, 2015; Frasco and Guilhermino, 2002; Gunderson et al, 2004; Gunderson et al, 2016). GST attaches the polar molecule glutathione to foreign chemicals thus facilitating clearance through the urine and bile (Newman, 1998).…”

Effects of chronic exposure to 12‰ saltwater on the endocrine physiology of juvenile American alligator (Alligator mississippiensis)

“…Although no longer endangered, alligators are commonly affected by both anthropogenic and natural environmental stressors. Whereas anthropogenic stressors generally include pollutants from domestic, agricultural and industrial sources (Crain et al, 1997;Guillette, 2000;Guillette et al, 1994;Gunderson et al, 2016;Tellez and Merchant, 2015), they can also include activities that alter alligator habitat hydrology, such as construction of canals, dredging, logging and oil/gas exploration. These activities can reduce FW input (from rivers and streams), increasing the likelihood of droughts and risk of saltwater (SW) intrusion from nearby coastal areas (Day et al, 2000;Herbert et al, 2015).…”