Effects of in ovo exposure to 3,3′,4,4′‐tetrachlorobiphenyl (PCB 77) on heart development in tree swallow (Tachycineta bicolor)

Abstract

Tree swallow (Tachycineta bicolor) eggs from 2 uncontaminated sites, the Patuxent Research Refuge (Laurel, MD, USA) and the Cobleskill Reservoir (Cobleskill, NY, USA) were dosed with polychlorinated biphenyl (PCB) 77 to evaluate effects on the developing cardiovascular system. To ensure embryonic viability, treatments were administered into the air cell at embryonic day 2.5 including: untreated (control), vehicle (filtered sterilized fatty acid mixture), 100 ng/g and 1000 ng/g egg. Eggs were dosed in the field with 0.2 mL/egg, returned to the nest, collected at embryonic day 13, hatched in the laboratory, and necropsied. The PCB 77-treated hatchlings were compared with uninjected, vehicle-injected, and environmentally exposed hatchlings collected from a PCB-contaminated Upper Hudson River (NY, USA) site. The PCB 77-treated embryos showed no effects on hatching success or hatchling mortality, heart index, or morphological measures of 4 distinct heart layers (heart width, length, septal thickness, total and ventricular cavity area) compared with controls. Hatchlings that had received PCB 77 exhibited increased incidence of a cardiomyopathy and absence of the ventricular heart wall compact layer (Chi square test; p < 0.001); environmentally exposed embryos showed no apparent effects. The compact layer is essential in development and overall heart function for ventricular cardiomyocyte proliferation and normal heart contraction. The finding that in ovo exposure to PCB 77 resulted in distinct cardiomyopathy has implications for long-term individual fitness. Environ Toxicol Chem 2018;37:116-125. C 2017 SETAC

Comparative Lethality of In ovo Exposure to PCB 126, PCB 77, and 2 Environmentally Relevant PCB Mixtures in Japanese Quail (Coturnix japonica)

“…Given the lack of a dose‐response relationship for mortality over the doses tested for PCB 77, any effects of exposure would likely be more subtle changes in biochemistry and physiology. These findings are consistent with our previous data in tree swallows in which embryonic exposure to PCB 77 did not impact mortality; however, there was greater incidence of cardiomyopathies (Carro et al ). It is interesting to note that despite the lack of an apparent dose‐response relationship for mortality for PCB 77, the quantifiable increase in mortality is similar to mortality increases above controls for the lowest doses of the other 3 treatments.…”

Dilated cardiomyopathy in a green-winged saltator (Saltator similis)

“…Krautwald-Junghanns et al (12) found dilation or hypertrophy of the ventricular myocardium in 15% of 107 psittacine birds evaluated. On the other hand, cardiomyopathies in passerine birds have not been reported to date, and heart diseases reported in this group are restricted to congenital heart malformations caused by environmental exposure to polychlorinated biphenyls during embryonic development, which results in alterations in the size and shape of the heart (2,4).…”

Avian Cardiovascular Disease Characteristics, Causes and Genomics

“…Environmental factors are also a consideration. A study into the effects of polychlorinated biphenyl (PCB) 77 showed that in the tree swallow (Tachycineta bicolor) in ovo exposure to the chemical results in higher levels of cardiomyopathy and ventricular wall abnormalities [83]. Age also had an effect on normal broiler roosters in comparison to mature roosters.…”