Thyroid and reproduction in amphibians and reptiles.

The relationship between the thyroid gland and reproduction in amphibians and reptiles has been studied for more than 100 years. Most studies suggest a positive involvement of thyroid hormones with some aspects of reproduction, but some studies support a negative role for thyroid hormones at certain life stages. Comprehensive studies of gene activation/suppression by thyroid hormones and their absence at various levels of the hypothalamo-pituitary-gonadal axis coupled with observations of adrenocorticoid activity, reproductive performance, and metabolic involvement are needed to understand this complex relationship.

Comparative Endocrinology: Past, Present, and Future.

Comparative endocrinology has traditionally focused on studies of the evolution of endocrine systems, regulation of hormone actions in animals, development of model systems, and the role of the environment in controlling hormone functions related to major life-history events. Comparative endocrinology also has made important contributions to basic research and clinical endocrinology. In recent years there has been a shift to a focus on anthropogenic chemical factors and their alteration of major life history events through endocrine disruption. During the 21st century, environmental comparative endocrinologists must play an important role in the identification and assessment of endocrine disruption on vertebrate and invertebrate animals and their environment as well as in monitoring remediation. All comparative biologists are encouraged to communicate their understanding of threats to biological systems to non-scientists to facilitate their understanding of the human impacts of various kinds of pollution and habitat destruction on wildlife and ecosystems as well as their long-term consequences.

The occurrence of intersex fishes in Boulder Creek, Colorado, is a recent phenomenon.

Gonads were examined visually and histologically from white sucker (Catostomus commersoni) and fathead minnows (Pimephales promelas) isolated from museum specimens collected from Boulder Creek, Colorado. These fishes were collected between 42 and 102 years ago before addition of large quantities of estrogenic chemicals via wastewater effluent was reported to disrupt reproductive structures and functions in white suckers living in Boulder Creek downstream of the wastewater treatment facility (WWTF) and in test exposures of fathead minnows to wastewater effluent at the WWTF. No evidence of abnormal external gonad appearance or histology (e.g., testicular oocytes, mixed gonadal tissue) were observed in male or female museum specimens of either species supporting the conclusion that observations of reproductive abnormalities, feminization, demasculinization, and altered sex ratios are recent phenomena.

Complex hand dexterity: a review of biomechanical methods for measuring musical performance.

Complex hand dexterity is fundamental to our interactions with the physical, social, and cultural environment. Dexterity can be an expression of creativity and precision in a range of activities, including musical performance. Little is understood about complex hand dexterity or how virtuoso expertise is acquired, due to the versatility of movement combinations available to complete any given task. This has historically limited progress of the field because of difficulties in measuring movements of the hand. Recent developments in methods of motion capture and analysis mean it is now possible to explore the intricate movements of the hand and fingers. These methods allow us insights into the neurophysiological mechanisms underpinning complex hand dexterity and motor learning. They also allow investigation into the key factors that contribute to injury, recovery and functional compensation. The application of such analytical techniques within musical performance provides a multidisciplinary framework for purposeful investigation into the process of learning and skill acquisition in instrumental performance. These highly skilled manual and cognitive tasks present the ultimate achievement in complex hand dexterity. This paper will review methods of assessing instrumental performance in music, focusing specifically on biomechanical measurement and the associated technical challenges faced when measuring highly dexterous activities.

Fish endocrine disruption responses to a major wastewater treatment facility upgrade.

The urban-water cycle modifies natural stream hydrology, and domestic and commercial activities increase the burden of endocrine-disrupting chemicals, such as steroidal hormones and 4-nonylphenol, that can disrupt endocrine system function in aquatic organisms. This paper presents a series of integrated chemical and biological investigations into the occurrence, fate, and effects of endocrine-disrupting chemicals in the City of Boulder Colorado's WWTF and Boulder Creek, the receiving stream. Results are presented showing the effects of a full-scale upgrade of the WWTF (that treats 0.6 m(3) s(-1) of sewage) from a trickling filter/solids contact process to an activated sludge process on the removal of endocrine-disrupting compounds and other contaminants (including nutrients, boron, bismuth, gadolinium, and ethylenediaminetetraacetic acid) through each major treatment unit. Corresponding impacts of pre- and postupgrade effluent chemistry on fish reproductive end points were evaluated using on-site, continuous-flow experiments, in which male fathead minnows (Pimephales promelas) were exposed for 28 days to upstream Boulder Creek water and WWTF effluent under controlled conditions. The upgrade of the WWTF resulted in improved removal efficiency for many endocrine-disrupting chemicals, particularly 17ß-estradiol and estrone, and fish exposed to the postupgrade effluent indicated reduction in endocrine disruption relative to preupgrade conditions.

Demasculinization of male fish by wastewater treatment plant effluent.

Adult male fathead minnows (Pimephales promelas) were exposed to effluent from the City of Boulder, Colorado wastewater treatment plant (WWTP) under controlled conditions in the field to determine if the effluent induced reproductive disruption in fish. Gonadal intersex and other evidence of reproductive disruption were previously identified in white suckers (Catostomus commersoni) in Boulder Creek downstream from this WWTP effluent outfall. Fish were exposed within a mobile flow-through exposure laboratory in July 2005 and August 2006 to WWTP effluent (EFF), Boulder Creek water (REF), or mixtures of EFF and REF for up to 28 days. Primary (sperm abundance) and secondary (nuptial tubercles and dorsal fat pads) sex characteristics were demasculinized within 14 days of exposure to 50% and 100% EFF. Vitellogenin was maximally elevated in both 50% and 100% EFF treatments within 7 days and significantly elevated by 25% EFF within 14 days. The steroidal estrogens 17ß-estradiol, estrone, estriol, and 17α-ethynylestradiol, as well as estrogenic alkylphenols and bisphenol A were identified within the EFF treatments and not in the REF treatment. These results support the hypothesis that the reproductive disruption observed in this watershed is due to endocrine-active chemicals in the WWTP effluent.

Antidepressant pharmaceuticals in two U.S. effluent-impacted streams: occurrence and fate in water and sediment, and selective uptake in fish neural tissue.

Antidepressant pharmaceuticals are widely prescribed in the United States; release of municipal wastewater effluent is a primary route introducing them to aquatic environments, where little is known about their distribution and fate. Water, bed sediment, and brain tissue from native white suckers (Catostomus commersoni) were collected upstream and at points progressively downstream from outfalls discharging to two effluent-impacted streams, Boulder Creek (Colorado) and Fourmile Creek (Iowa). A liquid chromatography/tandem mass spectrometry method was used to quantify antidepressants, including fluoxetine, norfluoxetine (degradate), sertraline, norsertraline (degradate), paroxetine, citalopram, fluvoxamine, duloxetine, venlafaxine, and bupropion in all three sample matrices. Antidepressants were not present above the limit of quantitation in water samples upstream from the effluent outfalls but were present at points downstream at ng/L concentrations, even at the farthest downstream sampling site 8.4 km downstream from the outfall. The antidepressants with the highest measured concentrations in both streams were venlafaxine, bupropion, and citalopram and typically were observed at concentrations of at least an order of magnitude greater than the more commonly investigated antidepressants fluoxetine and sertraline. Concentrations of antidepressants in bed sediment were measured at ng/g levels; venlafaxine and fluoxetine were the predominant chemicals observed. Fluoxetine, sertraline, and their degradates were the principal antidepressants observed in fish brain tissue, typically at low ng/g concentrations. A qualitatively different antidepressant profile was observed in brain tissue compared to streamwater samples. This study documents that wastewater effluent can be a point source of antidepressants to stream ecosystems and that the qualitative composition of antidepressants in brain tissue from exposed fish differs substantially from the compositions observed in streamwater and sediment, suggesting selective uptake.

Antidepressants at environmentally relevant concentrations affect predator avoidance behavior of larval fathead minnows (Pimephales promelas).

The effects of embryonic and larval exposure to environmentally relevant (ng/L) concentrations of common antidepressants, fluoxetine, sertraline, venlafaxine, and bupropion (singularly and in mixture) on C-start escape behavior were evaluated in fathead minnows (Pimephales promelas). Embryos (postfertilization until hatching) were exposed for 5 d and, after hatching, were allowed to grow in control well water until 12 d old. Similarly, posthatch fathead minnows were exposed for 12 d to these compounds. High-speed (1,000 frames/s) video recordings of escape behavior were collected and transferred to National Institutes of Health Image for frame-by-frame analysis of latency periods, escape velocities, and total escape response (combination of latency period and escape velocity). When tested 12 d posthatch, fluoxetine and venlafaxine adversely affected C-start performance of larvae exposed as embryos. Conversely, larvae exposed for 12 d posthatch did not exhibit altered escape responses when exposed to fluoxetine but were affected by venlafaxine and bupropion exposure. Mixtures of these four antidepressant pharmaceuticals slowed predator avoidance behaviors in larval fathead minnows regardless of the exposure window. The direct impact of reduced C-start performance on survival and, ultimately, reproductive fitness provides an avenue to assess the ecological relevance of exposure in an assay of relatively short duration.

Predator avoidance performance of larval fathead minnows (Pimephales promelas) following short-term exposure to estrogen mixtures.

Aquatic organisms exposed to endocrine disrupting compounds (EDCs) at early life-stages may have reduced reproductive fitness via disruption of reproductive and non-reproductive behavioral and physiological pathways. Survival to reproductive age relies upon optimal non-reproductive trait expression, such as adequate predator avoidance responses, which may be impacted through EDC exposure. During a predator-prey confrontation, larval fish use an innate C-start escape behavior to rapidly move away from an approaching threat. We tested the hypotheses that (1) larval fathead minnows exposed to estrogens, a primary class of EDCs, singularly or in mixture, suffer a reduced ability to perform an innate C-start behavior when faced with a threat stimulus; (2) additive effects will cause greater reductions in C-start behavior; and (3) effects will differ among developmental stages. In this study, embryos (post-fertilization until hatching) were exposed for 5 days to environmentally relevant concentrations of estrone (E1), 17beta-estradiol (E2), and 17alpha-ethinylestradiol (EE2) singularly and in mixture. Exposed embryos were allowed to hatch and grow in control well water until 12 days old. Similarly, post-hatch fathead minnows were exposed for 12 days to these compounds. High-speed (1000frames/s) video recordings of escape behavior were collected and transferred to National Institutes of Health Image for frame-by-frame analysis of latency period, escape velocity, and total escape response (combination of latency period and escape velocity). When tested 12 days post-hatch, only E1 adversely affected C-start performance of larvae exposed as embryos. Conversely, larvae exposed for 12 days post-hatch did not exhibit altered escape responses when exposed to E1, while adverse responses were seen in E2 and the estrogen mixture. Ethinylestradiol exposure did not elicit changes in escape behaviors at either developmental stage. The direct impact of reduced C-start performance on survival, and ultimately, reproductive fitness provides an avenue to assess the ecological relevance of exposure in an assay of relatively short duration.

Reproductive disruption in fish downstream from an estrogenic wastewater effluent.

To assess the impact of an estrogenic wastewater treatment plant (WWTP) effluent on fish reproduction, white suckers (Catostomus commersoni) were collected from immediately upstream and downstream (effluent site) of the city of Boulder, CO, WWTP outfall. Gonadal intersex, altered sex ratios, reduced gonad size, disrupted ovarian and testicular histopathology, and vitellogenin induction consistent with exposure to estrogenic wastewater contaminants were identified in white suckers downstream from the WWTP outfall and not at the upstream site. The sex ratio was female-biased at the effluent site in both the fall of 2003 and the spring of 2004; the frequency of males at the effluent site (17-21%) was half that of the upstream site (36-46%). Intersex white suckers comprised 18-22% of the population at the effluent site. Intersex fish were not found at the upstream site. Chemical analyses determined that the WWTP effluent contained a complex mixture of endocrine-active chemicals, including 17beta-estradiol (E2) 17alpha-ethynylestradiol, alkylphenols, and bisphenol A resulting in an estimated total estrogen equivalence of up to 31 ng E2 L(-1). These results indicate that the reproductive potential of native fishes may be compromised in wastewater-dominated streams.

Intersex and other reproductive disruption of fish in wastewater effluent dominated Colorado streams.

Intersex white suckers (Catostomus commersoni) were collected in Boulder Creek and the South Platte River downstream of wastewater treatment plant (WWTP) effluent but not at reference sites. Eighty-three percent of the 60 white suckers collected downstream of the Boulder WWTP in spring and fall were female compared to 45% upstream (n=33). Only female (n=16) and intersex white suckers (n=4) were collected in the South Platte River downstream of the Denver WWTP in the spring. Gonad deformities and delayed follicular maturation were noted in some white suckers in Boulder Creek and the South Platte River downstream of the WWTP effluents. Asynchronous ovarian development was found in some female white suckers downstream of the WWTP effluents, but not upstream. The types and extent of sexual disruption differed in each river studied.

Effects of steroids and dioxin (2,3,7,8-TCDD) on the developing wolffian ducts of the tiger salamander (Ambystoma tigrinum).

This study was undertaken to investigate effects of the prototypical dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on steroid-dependent development of the wolffian ducts of an amphibian, the tiger salamander (Ambystoma tigrinum). Larvae with immature gonads and undeveloped mullerian ducts were injected with the steroid hormones estradiol (E2), dihydrotestosterone (DHT), or vehicle alone. Additionally, steroid-treated and vehicle-control larvae were immersed in sub-lethal solutions of technical grade TCDD (0, 0.0003, 0.003, 0.03, 0.3, and 3.0 microg TCDD/L). Both steroid treatments stimulated hypertrophy of the wolffian duct epithelium and an increase in mean epithelial cell size. Only DHT treatment stimulated epithelial cell proliferation. TCDD stimulated wolffian duct hypertrophy through an increase in mean epithelial cell size. TCDD acted as an androgen agonist on wolffian duct epithelial area and epithelial cell size. TCDD had no effect on wolffian duct epithelium among E2-injected animals. Stimulatory effects on cell size were observed at 0.0003 microg/L TCDD in saline-injected animals and at 0.003 microg/L TCDD in DHT-injected animals. Both E2 and DHT stimulated growth of the wolffian ducts early in development. Technical grade TCDD alone mimics E2 and DHT action but exhibits an androgen-agonistic action in the presence of exogenously administered DHT. Implications of possible interactions between TCDD and xenosteroids are discussed.

Monoamines stimulate sex reversal in the saddleback wrasse.

Monoamine neurotransmitters (norepinephrine, dopamine, and serotonin) play an important role in reproduction and sexual behavior throughout the vertebrates. They are the first endogenous chemical signals in the regulation of the hypothalamo-pituitary-gonadal (HPG) axis. In teleosts with behavioral sex determination, much is known about behavioral cues that induce sex reversal. The cues are social, processed via the visual system and depend on the ratio of females to males in the population. The mechanisms by which these external behavioral cues are converted to an internal chemical regulatory process are largely unknown. The protogynous Hawaiian saddleback wrasse, Thalassoma duperrey, was used to investigate the biological pathway mediating the conversion of a social cue into neuroendocrine events regulating sex reversal. Because monoamines play an important role in the regulation of the HPG axis, they were selected as likely candidates for such a conversion. To determine if monoamines could affect sex reversal, drugs affecting monoamines were used in an attempt to either induce sex reversal under non-permissive conditions, or prevent sex reversal under permissive conditions. Increasing norepinephrine or blocking dopamine or serotonin lead to sex reversal in experimental animals under non-permissive conditions. Increasing serotonin blocked sex reversal under permissive conditions, while blocking dopamine or norepinephrine retarded the process. The results presented here demonstrate that monoamines contribute significantly to the control sex reversal. Norepinephrine stimulates initiation and completion of gonadal sex of reversal as well as color change perhaps directly via its effects on the HPG axis. Dopamine exercises inhibitory action on the initiation of sex reversal while 5-HT inhibits both initiation and completion of sex reversal. The serotonergic system appears to be an integral part of the pathway mediating the conversion of a social cue into a neuroendocrine event. The complex organization of neurochemical events controlling the psychosocial, physiological, and anatomical events that constitute reversal of sexual identity includes monoamine neurotransmitters.

Intraneuronal amyloid precursor protein (APP) and appearance of extracellular beta-amyloid peptide (abeta) in the brain of aging kokanee salmon.

Antibodies to human amyloid precursor protein (APP(695)) and beta-amyloid peptide (A beta(1-42)) were used to determine timing of amyloidosis in the brain of kokanee salmon (Oncorhynchus nerka kennerlyi) in one of four reproductive stages: immature (IM), maturing (MA), sexually mature (SM), and spawning (SP), representing a range of aging from somatically mature but sexually immature to spawning and somatic senescence. In IM fish, immunoreactive (ir) intracellular APP occurred in 18 of 23 brain regions. During sexual maturation and aging, the number of neurons expressing APP increased in 11 of these APP-ir regions. A beta-ir was absent in IM fish, present in seven regions in MA fish, moderately abundant in 15 regions in SM fish, and was most abundant in all brain regions of SP fish exhibiting A beta-ir. Intracellular APP-ir was observed in brain regions involved in sensory integration, olfaction, vision, stress responses, reproduction, and coordination. Intra- and extracellular A beta(1-42) immunoreactivity (A beta-ir) was present in all APP-ir regions except the nucleus lateralis tuberis (hypothalamus) and Purkinje cells (cerebellum). APP-ir and A beta deposition increase during aging. APP-ir is present in IM fish; A beta-ir usually appears first in MA or SM fish and increases in SM fish as does APP-ir. Extracellular A beta deposition dramatically increases between SM and SP stages (1-2 weeks) in all fish, indicating an extremely rapid and synchronized process. Rapid senescence observed in pacific salmon could make them a useful model to investigate timing of amyloidosis and neurodegeneration during brain aging.

Timing of neurodegeneration and beta-amyloid (Abeta) peptide deposition in the brain of aging kokanee salmon.

Brains of kokanee salmon (Oncorhynchus nerka kennerlyi) in one of four reproductive stages (sexually immature, maturing, sexually mature, and spawning) were stained with cresyl violet and silver stain to visualize neurodegeneration. These reproductive stages correlate with increasing somatic aging of kokanee salmon, which die after spawning. Twenty-four regions of each brain were examined. Brains of sexually immature fish exhibited low levels of neurodegeneration, whereas neurodegeneration was more marked in maturing fish and greatest in spawning fish. Neurodegeneration was present in specific regions of the telencephalon, diencephalon, mesencephalon, and rhombencephalon. Pyknotic neurons were observed in all regions previously reported to be immunopositive for A beta. Regions that did not exhibit neurodegeneration during aging included the magnocellular vestibular nucleus, the nucleus lateralis tuberis of the hypothalamus, and Purkinje cells of the cerebellum, all of which also lack A beta; perhaps these regions are neuroprotected. In 14 of 16 brain areas for which data were available on both the increase in A beta deposition and pyknosis, neurodegeneration preceded or appeared more or less simultaneously with A beta production, whereas in only two regions did A beta deposition precede neurodegeneration. This information supports the hypothesis that A beta deposition is a downstream product of neurodegeneration in most brain regions. Other conclusions are that the degree of neurodegeneration varies among brain regions, neurodegeneration begins in maturing fish and peaks in spawning fish, the timing of neurodegeneration varies among brain regions, and some regions do not exhibit accelerated neurodegeneration during aging.

Cortisol and Pacific Salmon: A New Look at the Role of Stress Hormones in Olfaction and Home-stream Migration.

Pacific salmon (genus Oncorhynchus) exhibit an interesting and uncommon life-history pattern that combines semelparity, anadromy, and navigation (homing). During smoltification, young salmon imprint on the chemical composition of their natal stream water (the home-stream olfactory bouquet or "HSOB"); they then migrate to the ocean where they spend a few years feeding prior to migrating back to their natal freshwater stream to spawn. Upstream migration is guided by the amazing ability to discriminate between the chemical compositions of different stream waters and thus identify and travel to their home-stream. Pacific salmon demonstrate marked somatic and neural degeneration changes during home-stream migration and at the spawning grounds. The appearance of these pathologies is correlated with a marked elevation in plasma cortisol levels. While the mechanisms of salmonid homing are not completely understood, it is known that adult salmon continuously utilize two of their primary sensory systems, olfaction and vision, during homing. Olfaction is the primary sensory system involved in freshwater homing and "HSOB" recognition, and will be emphasized here. Previously, we proposed that the increase in plasma cortisol during Pacific salmon home-stream migration is adaptive because it enhances the salmon's ability to recall the imprinted memory of the "HSOB" (Carruth, 1998; Carruth et al., 2000b). Elevated plasma concentrations of cortisol could prime the hippocampus or other olfactory regions of the brain to recall this memory and, therefore, aid in directing the fish to their natal stream. Thus, specific responses of salmon to stressors could enhance reproductive success.