Contamination acts as a genotype-dependent barrier to gene flow, causing genetic erosion and fine-grained population subdivision in Mussels from the Strait of Istanbul.

This study provides evidence of fine-grained genetic structuring in Mediterranean mussels (Mytilus galloprovincialis) from the Strait of Istanbul, caused by barriers to gene flow via contaminant-mediated selection. In this study, mitochondrial D-loop sequences were analyzed in mussels from 8 localities, all less than 30 kilometers apart, with differing contaminant loads. The results were: 1) Intra-population genetic differentiation (Φ) between sites with high and low contaminant loads was high (up to 0.

Biarticular mechanisms of the gastrocnemii muscles enhance ankle mechanical power and work during running.

The objective of the study was to explore how biarticular mechanisms of the gastrocnemii muscles may provide an important energy source for power and work at the ankle joint with increasing running speed. Achilles tendon force was quantified as a proxy of the triceps surae muscle force and the contribution of the monoarticular soleus and the biarticular gastrocnemii to the mechanical power and work performed at the ankle joint was investigated in three running speeds (transition 2.0 m s, slow 2.

Contractile Work of the Soleus and Biarticular Mechanisms of the Gastrocnemii Muscles Increase the Net Ankle Mechanical Work at High Walking Speeds.

Increasing walking speed is accompanied by an increase of the mechanical power and work performed at the ankle joint despite the decrease of the intrinsic muscle force potential of the soleus (Sol) and gastrocnemius medialis (GM) muscles. In the present study, we measured Achilles tendon (AT) elongation and, based on an experimentally determined AT force-elongation relationship, quantified AT force at four walking speeds (slow 0.7 m.

A Simplified Method for Considering Achilles Tendon Curvature in the Assessment of Tendon Elongation.

The consideration of the Achilles tendon (AT) curvature is crucial for the precise determination of AT length and strain. We previously established an ultrasound-kinematic-based method to quantify the curvature, using a line of reflective foil skin markers covering the AT from origin to insertion. The current study aimed to simplify the method by reducing the number of markers while maintaining high accuracy.

Quantifying mechanical loading and elastic strain energy of the human Achilles tendon during walking and running.

The purpose of the current study was to assess in vivo Achilles tendon (AT) mechanical loading and strain energy during locomotion. We measured AT length considering its curve-path shape. Eleven participants walked at 1.

Effects of Military activity and habitat quality on DNA damage and oxidative stress in the largest population of the Federally threatened gopher tortoise.

Department of Defense lands are essential for providing important habitat for threatened, endangered, and at-risk species (TER-S). However, there is little information on the effects of military-related contaminants on TER-S on these lands in field situations. Thus, this study examined genotoxicity and oxidative stress in gopher tortoises (Gopherus polyphemus) on Camp Shelby, MS-the largest known population of this species, which is listed as an "endangered species" in Mississippi and a "threatened species" by the U.

Subchronic and chronic developmental effects of copper oxide (CuO) nanoparticles on Xenopus laevis.

Metal oxide nanoparticles, such as copper oxide (CuO), are mass produced for use in a variety of products like coatings and ceramics. Acute exposure to CuO nanoparticles has caused toxicity to many aquatic organisms, yet there is no information on the effect of prolonged CuO nanomaterial exposures. This study examined effects of chronic exposure to CuO nanoparticles on Xenopus laevis growth and development.

DNA damage in cichlids from an oil production facility in Guatemala.

This study focused on several wetlands in Laguna del Tigre National Park (Guatemala) as part of Conservation International's Rapid Assessment Program. Sediment and water samples were collected from a laguna near Xan field, Guatemala's largest oil facility, and three other sites for determination of levels of polycyclic aromatic hydrocarbons (PAHs). Cichlid fish (Thorichthys meeki and Vieja synspila) were collected for determination of DNA strand breakage (by gel electrophoresis), chromosomal breakage (flow cytometry), and fin erosion.

Acute effects of Fe₂O₃, TiO₂, ZnO and CuO nanomaterials on Xenopus laevis.

Metal oxide nanomaterials have exhibited toxicity to a variety of aquatic organisms, especially microbes and invertebrates. To date, few studies have evaluated the toxicity of metal oxide nanomaterials on aquatic vertebrates. Therefore, this study examined effects of ZnO, TiO(2), Fe(2)O(3), and CuO nanomaterials (20-100 nm) on amphibians utilizing the Frog Embryo Teratogenesis Assay Xenopus (FETAX) protocol, a 96 h exposure with daily solution exchanges.

Effects of ZnO nanomaterials on Xenopus laevis growth and development.

The objectives of this study were to quantify uptake and developmental effects of zinc oxide nanomaterials (nano-ZnO) on Xenopus laevis throughout the metomormosis process. To accomplish this, X. laevis were exposed to aqueous suspensions of 40-100 nm nano-ZnO beginning in-ovo and proceeding through metamorphosis.

Arsenate and perchlorate toxicity, growth effects, and thyroid histopathology in hypothyroid zebrafish Danio rerio.

Exposure to perchlorate or other thyrotoxic compounds can cause hypothyroidism in most vertebrates, and this may affect levels of endogenous antioxidants and cause oxidative stress. Arsenic also induces oxidative stress in animals by modifying the antioxidant capacity and may alter the thyroid homeostasis. Therefore, hypothyroidism may affect the toxicity of arsenate.

Uptake, elimination, and relative distribution of perchlorate in various tissues of channel catfish.

This study was undertaken to determine the kinetics of uptake and elimination of perchlorate in channel catfish, Ictalurus punctatus. Perchlorate--an oxidizer used in solid fuel rockets, fireworks, and illuminating munitions--has been shown to effect thyroid function, causing hormone disruption and potential perturbations of metabolic activities. For the uptake study, catfish were exposed to 100 mg/L sodium perchlorate for 12 h to 5 d in the laboratory.

Uptake, accumulation and depuration of sodium perchlorate and sodium arsenate in zebrafish (Danio rerio).

In toxicokinetics studies, interactions between chemicals in mixtures has been largely neglected. This study examines a mixture of perchlorate and arsenate because (1) they have the potential to co-occur in contaminated aquatic habitats, and (2) a previous study by the authors found possible toxicological interactive effects. In the present study, zebrafish (Danio rerio) were exposed to two concentrations of sodium perchlorate (10 and 100 mg l(-1)), sodium arsenate (1 and 10 mg l(-1)), and the mixture-sodium perchlorate+sodium arsenate (10+1 mg l(-1) and 100+10 mg l(-1) Na(2)HAsO(4)-high mixture) for 90 d.

Thyrotoxicity of sodium arsenate, sodium perchlorate, and their mixture in zebrafish Danio rerio.

Both perchlorate and arsenate are environmental contaminants. Perchlorate is a definitive thyroid disruptor, and arsenic may disrupt thyroid homeostasis via multiple pathways. To evaluate the effects of sodium perchlorate and sodium arsenate on thyroid function and possible interactions between them, zebrafish (Danio rerio) were exposed to sodium perchlorate (10 and 100 mg/L), sodium arsenate (1 and 10 mg/L), and the mixture sodium perchlorate + sodium arsenate (10 + 1 and 100 + 10 mg/ L) for up to 90 days.

Seasonal variations in the concentration of microcystin-LR in two lakes in western Texas, USA.

Seasonal variations in the concentration of microcystin-LR (MCLR) in Buffalo Springs Lake (BSL) and Lake Ransom Canyon (LRC; both locations in Lubbock, TX, USA) were monitored from 2003 to 2004. In BSL, the average concentrations of MCLR were 1.78 +/- 1.

The thyroid endocrine disruptor perchlorate affects reproduction, growth, and survival of mosquitofish.

The perchlorate anion--an oxidizer found in rockets, missiles, some ammunition, flares, airbags, and fireworks--occurs as a contaminant in ground and surface water in many parts of the United States. Its toxic effects include inhibition of thyroid hormone synthesis. To investigate its chronic toxicity, mosquitofish (Gambusia holbrooki) adults and fry were exposed to aqueous sodium perchlorate at 1, 10, and 100mg/L, and growth and reproductive performance (fecundity, eggs/embryos mass, and gonadosomatic index [GSI]) were determined.

Evidence of altered gene flow, mutation rate, and genetic diversity in redbreast sunfish from a pulp-mill-contaminated river.

To determine effects of pulp mill effluent on population genetic structure, redbreast sunfish (Lepomis auritus) were collected from several sites along the Pigeon River, NC, as well as from reference sites. Previous studies found effects on molecular, biochemical, physiological, population, and community level endpoints in these populations. The population genetic structure of these fish was determined using the randomly amplified polymorphic DNA (RAPD) technique.

Comparative acute and combinative toxicity of aflatoxin B1 and fumonisin B1 in animals and human cells.

Aflatoxin B(1) (AFB(1)) and fumonisin B(1) (FB(1)) are important food-borne mycotoxins. The co-contamination of food stuffs with these two mycotoxins is well known and has been possibly implicated in the development of human hepatocellular carcinoma in high risk regions around the world. In this study the acute and combinative toxicity of AFB(1) and FB(1) were tested in F-344 rats, mosquitofish (Gambusia affinis), immortalized human hepatoma cells (HepG2) and human bronchial epithelial cells (BEAS-2B).

Thyroid endocrine disruption in stonerollers and cricket frogs from perchlorate-contaminated streams in east-central Texas.

In October 2001 and March 2002, a field survey of central stonerollers (Campostoma anomalum) from perchlorate-contaminated streams in central Texas was conducted to assess thyroid endocrine disruption. A survey of adult male and female cricket frogs (Acris crepitans) was performed at the same site between 2001 and 2003. Perchlorate is an oxidizer primarily used in solid-fuel rockets, and many sites that processed or used perchlorate are now contaminated.

Uptake and elimination of perchlorate in eastern mosquitofish.

The purpose of this study was to investigate the uptake and elimination of perchlorate in eastern mosquitofish (Gambusia holbrooki). Fish were exposed to 0.1-1000 mg/l sodium perchlorate for 12h, 1, 2, 5, 10, and 30 days, and perchlorate was determined in whole body extracts.

Comparative acute and combinative toxicity of aflatoxin B1 and T-2 toxin in animals and immortalized human cell lines.

Aflatoxin B1 (AFB1) and T-2 toxin (T-2) are important food-borne mycotoxins that have been implicated in human health and as potential biochemical weapons threats. In this study the acute and combinative toxicity of AFB1 and T-2 were tested in F-344 rats, mosquitofish (Gambusia affinis), immortalized human hepatoma cells (HepG2) and human bronchial epithelial cells (BEAS-2B). Preliminary experiments were conducted in order to assess the acute toxicity and to obtain LD50, LC50 and IC50 values for individual toxins in each model, respectively.

DNA strand length and EROD activity in relation to two screening measures of genotoxic exposure in Great Lakes herring gulls.

We collected tissues from herring gulls (Larus argentatus) nesting within and outside of the Great Lakes basin. Genotoxin exposure was assessed as fluorescent aromatic compounds (FACs) in bile and SOS Chromotest-inducing activity in muscle extracts. We determined whether these exposures were associated with decreased erythrocyte DNA strand length and/or induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity.

Joint toxicity of sodium arsenate and sodium perchlorate to zebrafish Danio rerio larvae.

Joint toxicity of arsenate and perchlorate was tested in larvae of Danio rerio. Results indicated that the 96-h median lethal concentrations of sodium arsenate and sodium perchlorate were 258.8 and 1,401.