Associations between organohalogen concentrations and transcription of thyroid-related genes in a highly contaminated gull population

Relationships between polybrominated diphenyl ethers and transcription and activity of type 1 deiodinase in a gull highly exposed to flame retardants

“…Because the ring‐billed gulls have been chronically exposed in their environment to high concentrations of BDE‐209 and other PBDEs , perturbations of their HPT axis may have been elicited. In fact, a study from our research group on Montreal‐breeding ring‐billed gulls from the same colony uncovered multiple relationships among circulating thyroid hormone levels, mRNA levels of several thyroid‐related genes, and PBDE concentrations . Hence, compensatory mechanisms of the HPT axis could explain, at least in part, the absence of an association between total D1 activity and liver BDE‐209 concentrations in ring‐billed gulls.…”

“…Gene sequences were not available for D1 or the 3 reference genes (see below) for ring-billed gulls. A primer pair designed by Crump et al [22] for chicken (Gallus gallus) D1 (access number: NM_001097614.1; 5 0 -TCTTTGTGCTGAAGGT-GAAGTGG-3 0 [forward] and 3 0 -AGGTCGGTTATCTCG-CATGAAAC-5 0 [reverse]; amplicon length 133 bp) and manufactured by IDT was validated for ring-billed gulls as part of a companion study [20]. Primer pairs for the 3 reference genes were designed based on chicken mRNA sequences available at the National Center for Biotechnology Information (NCBI) with Primer-BLAST from the NCBI (Primer3 with Blast [23]).…”

“…Moreover, high PBDE exposure in male ring‐billed gulls from the Montreal area has been suggested to adversely affect bone (tarsus) mineral density (i.e., bone tissue demineralization) , which could be linked, among other factors, to thyroid hormone disruption. Recent findings from our laboratory further showed that PBDE concentrations in ring‐billed gulls were positively associated with the ratio of total T 4 to T 3 levels in plasma, and transcription of several genes involved in the hypothalamic–pituitary–thyroid (HPT) axis (i.e., synthesis, metabolism, transport, and action) . We hypothesized that D1 transcription and in vitro activity in livers of ring‐billed gulls are related to liver concentrations of BDE‐209 and its potential debromination products.…”

Toxic Effects and Mechanisms of Polybrominated Diphenyl Ethers

“…These results indicate that excessive ER stress, defective autophagy and the resultant apoptosis are thought to be involved in maternal thyroid harm after perigestational PBDE-47 exposure [122][123][124]. Besides, further studies showed that oxidative damage and hypothalamic-pituitary-thyroid (HPT) axis-related gene alterations may be the underlying mechanisms involved in the toxicity of PBDEs (PBDE-47, PBDE-71, PBDE-99, PBDE-209) [125][126][127][128][129][130][131][132][133][134]. The mechanisms are shown in Figures 2 and 3.…”

Dynamics and effects of plastic contaminants’ assimilation in gulls

“…Yet, such chemical process is still poorly studied and there is almost no information regarding potential hazardous effects in animal physiological processes. Even though it was already reported that gulls accumulate Polybrominated Diphenyl Ethers (PBDEs) [4], there is no information linking plastic ingestion with leaching and accumulation of these chemicals in different tissues. Moreover, it is still not fully known how PBDEs affect gulls' health and stress parameters.…”