Biology subjects

Kohlman, E.

Publications and source records attributed to Kohlman, E..

3 recordsLinked to original sources

bioRxiv2024

Sub-chronic and acute toxicity of 6PPD-quinone to early-life stage rainbow trout (Oncorhynchus mykiss)

N-(1,3-Dimethylbutyl)-N-phenyl-p-phenylenediamine-quinone (6PPD-Q) is a derivative of rubber tires which leaches into surface waters when tire particles are swept into roadway runoff. 6PPD-Q has been identified as a potential cause of urban runoff mortality syndrome in coho salmon, and subsequent research has determined a wide species variation in toxicity among fishes. While adult rainbow trout are known to be sensitive, there is limited research on their early-life stages. Given that early-life stages of fish are often more sensitive than adults, the aim of these studies was to assess the acute and sub-chronic toxicity of 6PPD-Q in early-life stage rainbow trout. Rainbow trout alevins were exposed from hatch until 28 days post-hatch (dph) to time-weighted average 6PPD-Q concentrations ranging from 0.06-2.35 g/L. From these studies, a 28-day median lethal dose (LC50) of 0.56 g/L was derived. Morphological deformities were observed during the exposure period, including pooling of blood in the caudal fin. A follow-up acute study with exogenously feeding rainbow trout fry revealed a 96-hour LC50 of 0.47 g/L. These studies indicate that early-life stage rainbow trout are more sensitive than previously studied sub-adults, with exogenously feeding fry being the most sensitive life stage studied so far, and that sub-chronic exposure to 6PPD-Q can result in developmental abnormalities. This research highlights the importance of utilizing early-life stage studies to determine the most sensitive benchmark concentrations and their value in determining sub-lethal effects.

pharmacology and toxicology↗

bioRxiv2024

Xenometabolome of Early-Life Stage Salmonids Exposed to 6PPD-Quinone

N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q) is a ubiquitous transformation product (TP) derived from the rubber tire antioxidant N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and is acutely toxic to certain species of Salmonidae. Not all salmonids are sensitive to acute lethality caused by 6PPD-Q, with 6PPD-Q potency varying by several orders of magnitude among teleosts. The main driver(s) of species sensitivity differences is (are) a pressing question, with one area of interest examining whether differences in teleosts ability to biotransform and detoxify 6PPD-Q could be a key factor. This study utilized liquid-chromatography high-resolution mass spectrometry (LC-HRMS) to assess biotransformation and metabolome-wide effects of 6PPD-Q on early-life stage salmonids, including two sensitive species, rainbow trout (Oncorhynchus mykiss) and lake trout (Salvelinus namaycush), and one tolerant species, brown trout (Salmo trutta). Three phase I TPs and seven phase II TPs were detected, with differences in peak areas revealing that brown trout had the greatest ability to detoxify 6PPD-Q. Monohydroxylated TPs were verified using co-developed analytical standards that will be of use for future biomonitoring and exposure assessment. Several endogenous metabolites were found to be dysregulated in rainbow and lake trout, indicative of mitochondrial dysfunction, altered metabolism, and disrupted membrane permeability. Results of this study indicate a difference in the biotransformation capability of 6PPD-Q among Salmonidae fish species and subsequent unique metabolome responses. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=62 SRC="FIGDIR/small/598661v2_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@1931a42org.highwire.dtl.DTLVardef@a0f446org.highwire.dtl.DTLVardef@10540d0org.highwire.dtl.DTLVardef@1e21b49_HPS_FORMAT_FIGEXP M_FIG C_FIG SynopsisInter-species salmonid differences in the biotransformation capability of 6PPD-Q leads to sensitivity variability and subsequent unique metabolome responses.

pharmacology and toxicology↗

bioRxiv2024

Acute and sub-chronic toxicity of 6PPD-quinone to early-life stage lake trout (Salvelinus namaycush)

N-(1,3-Dimethylbutyl)-N-phenyl-p-phenylenediamine-quinone (6PPD-q) is a rubber-tire derivative which leaches into surface waters from roadway runoff, from tire particles and has been identified as a possible driver of urban runoff mortality syndrome in coho salmon. Sensitivity to this toxicant is highly variable across fish species and life stages. With environmental concentrations meeting or exceeding toxicity thresholds in sensitive fishes, the potential for ecologically relevant effects is significant. There is currently no data regarding the sensitivity of lake trout (Salvelinus namaycush) to 6PPD-q. As early-life stages of fishes are typically more sensitive than adults, the goal of these studies was to evaluate the acute and sub-chronic toxicity of 6PPD-q to early-life stage lake trout. Alevins exposed from hatch until 45 days post hatch (dph) to time-weighted average 6PPD-q concentrations ranging from 0.22-13.5 g/L exhibited a 45-day median lethal dose (LC50) of 0.39 g/L. Deformities throughout growth were observed, with a unique pooling of blood observed in the caudal fin and eye. A subsequent acute study with exogenously feeding lake trout fry determined a 96-hr LC50 of 0.50 g/L. From these studies we can conclude that lake trout alevins and exogenously feeding fry are sensitive to 6PPD-q, which underscores the relevance of this chemical to inland freshwater ecosystems.

physiology↗