MP10 PCB Toxicity in Aquatic Organisms- Endocrine Effects|
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall
P120 (RIP-1117-661042) Developmental exposure to PCBs through the placenta-like paternal brood pouch of two pipefishes.
Start time: 8:00 AM
Ripley, Jennifer1, Foran, Christy1, 1 West Virginia University, Morgantown, WV, USA
Pipefishes and seahorses of the family Syngnathidae are characterized by a unique mode of reproduction in which the male carries the embryos from fertilization until the fry are free-swimming in a specialized organ commonly referred to as the brood pouch. In an earlier study we investigated the role of the paternal brood pouch in nutrient transfer. We uncovered differences between two related pipefish species of the Chesapeake Bay in the relative contribution of males and females to developing offspring. Fry become implanted adjacent to blood vessels in the male brood pouch and females produce nutritionally poor eggs in the Northern pipefish, Syngnathus fuscus. On the contrary, females of the Dusky pipefish, Syngnathus floridae, produce nutrient-rich eggs which males appear to utilize as nurse eggs. Because of the potential for lipophilic contaminants to be transferred to developing pipefish through the paternal brood pouch, pipefish are likely to be exposed to contaminants during critical stages of development, analogous to human in utero exposure. We hypothesize that toxicant exposure during brooding will exhibit a greater impact on development of S. fuscus offspring than S. floridae, stemming from the production of sperm-like gametes by S. fuscus females versus nutrient-laden eggs by S. floridae and a related decline in dependence on paternal resources. We mated pipefish, collected from a relatively pristine site in Chincoteague Bay, Virginia, in the laboratory and exposed brooding males to high and low environmental concentrations of the PCB mixture Aroclor 1254 until fry were released. We indeed found S. fuscus development was impacted. Pipefish provide a unique model to investigate developmental impairment from placental exposure; due to the accessibility to brood fry and the large number of young per brood, the impact of embryonic contaminant exposure can be assessed rapidly.
P121 (KHA-1117-838618) Neuroendocrine Toxicity of Aroclor 1254 and Selected PCB Congeners in Atlantic Croaker.
Start time: 8:00 AM
Khan, I1, Berg, H1, Thomas, P1, 1 The University of Texas at Austin, Marine Science Institute, Port Aransas, TX, USA
Aroclor 1254 has been shown to impair reproductive neuroendocrine function in the Atlantic croaker, Micropogonias undulatus. In addition, we have identified hypothalamic tryptophan hydroxylase (TPH), the rate-limiting enzyme in serotonin synthesis, as a target of PCB neuroendocrine toxicity. A previous study in rats has implicated di-ortho-substituted non-coplanar PCB congeners in the inhibition of a similar enzyme, tyrosine hydroxylase, which is the rate-limiting enzyme in dopamine synthesis. Therefore, the present study was designed to investigate whether di-ortho-substituted congeners (PCB 47, PCB 153) or a coplanar congener (PCB 77) present in Aroclor 1254 could be responsible for reproductive impairment observed in croaker exposed to the PCB mixture. Fish were exposed to PCB 47 and PCB 153 in the diet (0, 0.2 and 1.0 mg/kg body weight/day) for 30 days and to PCB 77 (0.01 and 0.1 mg/kg body weight/day) for 15 days. Neither PCB 47 nor PCB 153 altered hypothalamic TPH activity or gonadal growth in croaker at doses similar to the effective doses of the Aroclor 1254 mixture. Therefore, these ortho--substituted PCB congeners known to be neurotoxic in mammalian systems are unlikely to contribute to Aroclor1254-induced reproductive neuroendocrine disruption in croaker. In contrast, PCB 77 significantly inhibited hypothalamic TPH activity and gonadal growth at doses much lower than the effective doses of Aroclor 1254. Interestingly, the decreases in TPH activity after Aroclor 1254 and PCB 77 exposures were not accompanied by reduced TPH protein content. Thus, the decrease in TPH activity does not appear to be caused by alterations in TPH protein and may involve other modes of TPH inactivation. The results provide first evidence for the disruption of reproductive neuroendocrine function by a coplanar PCB congener and may suggest involvement of oxidative processes in PCB neuroendocrine toxicity.
P122 (SPA-1117-855176) Creek chub (Semotilus atromaculatus Mitchill) reproduction in PCB-contaminated streams in Indiana.
Start time: 8:00 AM
Sparks, D1, Simon, T1, Tosick, M1, Millsap, D1, 2, Henshel, D2, 1 U.S. Fish and Wildlife Service, Bloomington, IN, USA2 Indiana University, Bloomington, IN, USA
We examined creek chubs from two PCB contaminated streams (Clear Creek and Richland Creek) at three locations and a reference stream (Little Indian Creek) to determine if reproductive measures were correlated with in-situ PCB exposure. Throughout this study, no spawning activity was observed at either location in Clear Creek, although some very small young-of-the-year creek chub fry were observed at the downstream location (CC2) by late summer. Creek chub nests were observed in both Richland Creek and Little Indian Creek but young of the year were common only in Little Indian Creek. Differences in synchronization of male and female sexual maturation were observed at the PCB sites. By mid-May at the reference site spawning was complete. We observed no reference females with maturing or ripe ova, whereas at our PCB contaminated locations several females were found carrying deteriorating ova in various stages of maturity as late as July. At CC2, we observed females with deteriorating ovaries in 1 and 2-year olds, and older age classes of females were absent. Both egg quality (e.g. shape, coloration) and egg sizes were reduced at the PCB-contaminated sites. Males at the PCB-contaminated sites tended to exhibit female secondary sex characteristics, with reductions in seasonal testes maturation and nuptial tubercle development. We observed significant differences in ovary weight and fecundity between PCB sites and the reference site. The percent volume of developing ova were significantly different between PCB sites and the reference site for early maturing, mature, and ripe ova, but not latent ova. A small follow-up study was conducted at 4 PCB-contaminated streams and a reference site wherein females were collected just prior to spawning and ovary conditions were qualitatively assessed (GSI, maturation, coloration) and regressed against congener specific PCB analysis of the ovaries and whole body concentrations.
P123 (EIS-1116-596103) PCB exposure in snapping turtles: effects on growth, metabolism and behavior.
Start time: 8:00 AM
Eisenreich, K1, Kelly, S1, Rowe, C1, 1 University of Maryland Center for Environmental Scienc - Chesapeake Biological Laboratory
Subtle changes in thyroid activity can significantly alter developmental processes due to the extreme sensitivity of embryos/fetuses to thyroid hormones. While the thyroid plays a major role in growth and metabolic processes, it also regulates neurological development. Thus, maternal transfer of PCBs to developing offspring would be expected to impair neurological development, with potential effects on learning and behavior. We examined the individual and interactive influences of maternal contributions of PCBs and food-bourne PCBs in natural prey items on snapping turtles (Chelydra serpentina) in the Hudson River Superfund site over the first year post-hatching. Measurements of carapace length and width, plastron length, and wet mass were used to quantify growth differences between hatchlings from different exposure regimes. In addition, respirometry was used to examine how potential metabolic anomalies correlated with PCB-related thyroid effects. Finally, four behavioral assays were conducted to identify potential relationships between thyroid-mediated neurological development processes and correlates with individual fitness. Behavioral assays included response to a physical stimulus and escape speed, response to a visual stimulus, righting response, and foraging success. While measurements of thyroid hormones in the juveniles have not yet been conducted, data on circulating thyroxine levels in adult turtles from the Superfund site and nearby reference sites will be presented. As PCBs perturb the thyroid system with the same mechanistic pathways in all life stages, the adult data will serve as a surrogate metric for thyroid hormone levels in the juveniles.
P123b (LER-1117-643474) Effects of aqueous exposure to Aroclor 1254 on smolt development and immune function in Atlantic salmon, Salmo salar.
Start time: 8:00 AM
Lerner, D1, 2, Iwanowicz, L1, 3, Blazer, V3, McCormick, S2, 1 University of Massachsuetts, Amherst, MA, USA2 USGS, Leetown Science Center, Conte Anadromous Fish Research Center, Turners Falls, MA, USA3 USGS, Leetown Science Center, National Fish Health Research Laboratory, Kearneysville, WV, USA
PCBs exist as persistent organic pollutants in numerous river systems in the United States and are implicated as endocrine disruptors and immunomodulators. Here we investigate the effects of aqueous PCB exposure (1 or 10 ppb Aroclor 1254) on plasma hormone concentrations, changes in osmoregulatory capacity, and behavior associated with smolt development and the mitogen-stimulated lymphoproliferative response of anterior kidney leukocytes in Atlantic salmon. Fish were exposed as smolts for 21 days and examined immediately after exposure, or exposed as post-hatch larvae for 21 days and examined 15 months after exposure. Plasma concentrations of cortisol, growth hormone, insulin-like growth factor I, and thyroid hormones were not significantly impacted, however exposure to 10 ppb Aroclor during smolting reduced gill Na, K-ATPase activity, plasma chloride concentration, and seawater preference. The proliferative response to the T cell mitogens CON A and PHA-P was significantly increased in smolts exposed to 10 ppb, and the PHA-P response was significantly increased in the 1 ppb group. In fish treated as larvae and tested 15 months later, the PHA-P sensitive populations exhibited elevated proliferation in the 1 and 10 ppb groups while the PWM response was significantly increased only in the 10 ppb group. These results suggest that the effects of Aroclor 1254 on immune function are disassociated from endocrine factors critical to smolting.