Effects of Hypoxia and Sedimentary Naphthalene on the Activity of <Emphasis Type="Italic">N</Emphasis>-acetyl-<Emphasis Type="Italic">β</Emphasis>-Glucosaminidase in the Epidermis of the Brown Shrimp, <Emphasis Type="Italic">Penaeus aztecus</Emphasis>

The brown shrimp, Penaeus aztecus, is subject to dual stresses of environmental hypoxia and contamination of polycyclic aromatic hydrocarbons (PAHs) in the northern Gulf of Mexico. The effects of hypoxia and sedimentary naphthalene, administered alone and in combination, on epidermal activity of N-acetyl-β-glucosaminidase (NAG), a biomarker for molt-interfering effects in P. aztecus, were investigated. It was found that hypoxia and sedimentary naphthalene, when given simultaneously, significantly inhibited epidermal NAG activity, suggesting that these two environmental stressors together can have adverse effects on molting of the brown shrimp. The results of this study also show that sedimentary naphthalene potentiates hypoxia effects on epidermal NAG activity.     

Metal Accumulation and Binding Protein Induction in <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis>, <Emphasis Type="Italic">Scapharca inaequivalvis</Emphasis>, and <Emphasis Type="Italic">Tapes philippinarum</Emphasis> from the Lagoon of Venice

Heavy metal pollution is known to be widespread in the sediments of the Lagoon of Venice. Therefore, physiological parameters influenced by this form of contamination were examined. The bivalve molluscs blue mussel (Mytilus galloprovincialis), ark clam (Scapharca inaequivalvis), and Japanese littleneck (Tapes philippinarum) were sampled in two sites (Marghera, Chioggia) every 3 months for 1 year. The digestive gland and gills of each bivalve were analyzed. The concentrations of essential and nonessential metals (including chromium, manganese, iron, cobalt, nickel, copper, zinc, and cadmium) were determined. Because glutathione and metallothioneins (MTs) are involved in metal homeostasis and detoxification, their concentrations were evaluated in relation to metal concentrations. Results show that (1) all three studied species accumulate metals to a considerable extent, with some species-specific differences between the digestive gland and gills; (2) gills are a good tissue to evaluate pollution by examining the MT content. In particular, the correlation between Zn and MT levels in the gills indicates that M. galloprovincialis and S. inaequivalvis are sentinel organisms and can be used specifically for Zn pollution; (3) T. philippinarum accumulates Cu in the digestive gland more readily than the other two bivalves and therefore has the highest MT. Received: 20 December 2001/Accepted: 11 November 2002     

<Emphasis Type="Italic">GSTM1</Emphasis> and <Emphasis Type="Italic">APE1</Emphasis> genotypes affect arsenic-induced oxidative stress: a repeated measures study

Background  

Chronic arsenic exposure is associated with an increased risk of skin, bladder and lung cancers. Generation of oxidative stress may contribute to arsenic carcinogenesis.     

Effects of Temperature on the Sensitivity of <Emphasis Type="Italic">Gammarus</Emphasis><Emphasis Type="Italic">aequicauda</Emphasis> (Martynov, 1931) to Cadmium

Gammarus aequicauda, collected at different times of the year was used to assess the mortality rates and the sensitivity to cadmium (96 h LC50), at different laboratory temperatures (10, 15, 20, 25°C). The survival in 10 days sediment control test, was high at all tested temperatures, ranging from 4 ± 1% at 10°C (winter collection) to 13.3 ± 2.1% at 25°C (spring collection). The 96 h-LC50 values recorded, ranged from 1.50 mgCd/L in winter at 10°C to 0.10 mgCd/L in spring and summer at 25°C. The results showed that temperature and season of collection influenced mortality rates and G. aequicauda sensitivity to cadmium.     

Soil <Emphasis Type="Italic">Pseudomonas</Emphasis> Community Structure and Its Antagonism Towards <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> Under the Stress of Acetochlor

In a microcosm experiment, the amplified ribosomal DNA restriction analysis was adopted to investigate the Pseudomonas community structure in soils applied with different concentrations (0, 50, 150, and 250 mg/kg) of acetochlor, and an in vitro assay was made to examine the antagonistic activity of isolated Pseudomonas strains acting on soil-borne pathogen Rhizoctonia solani. The results showed that acetochlor application changed the community structure of Pseudomonas in aquic brown soil. The diversity of Pseudomonas and the amount of isolated Pseudomonas strains with antagonistic activity decreased with an increasing acetochlor concentration, and the toxic effect of acetochlor reached to a steady level at 150–250 mg/kg.     

<Emphasis Type="Italic">Passing It On</Emphasis> During a <Emphasis Type="Italic">Day In The Life</Emphasis> of Resilient Adolescents in Diverse Communities Around the Globe

This social-ecological inquiry explores youth resiliency in diverse communities using innovative qualitative visual methodologies. It engages adolescents in a process of sharing their daily experiences and reflecting on the resources they bring to bear to thrive in the face of geographic and social relocations. The four youth participants were identified by local community advisors as especially resilient teenagers despite experiencing transitions that could provoke risks to normative development. The youths were interviewed and videotaped during a weekend day in [their] lives. They also engaged in deliberations on that day; took part in a photo elicitation that reflected on significant people, places, and objects in their environments; and responded to a resilience questionnaire. These visual data and the youths’ deliberations were analyzed for themes of positive identity and personal control observed within and across communities by their passing on the nurturant interchanges they themselves had experienced during that day.     

Investigation of the Multixenobiotic Resistance Mechanism in the Freshwater Fishes Western Mosquitofish, <Emphasis Type="Italic">Gambusia affinis</Emphasis>, and Bluegill Sunfish, <Emphasis Type="Italic">Lepomis macrochirus</Emphasis>

The purpose of the study was to evaluate multixenobiotic resistance mechanism expression as a biomarker for contaminant exposure in freshwater fishes. Exposure to a known mammalian inhibitor (verapamil, 10 μM) and inducer (rhodamine 123, 3 μM) on the transport protein P-glycoprotein (Pgp) was investigated in the liver of the western mosquitofish and bluegill sunfish. No differences in the activity or expression of Pgp were measured in either species using a fluorometric accumulation assay and western blot analyses. The preliminary results from this study indicate that this detoxification mechanism may not be a sensitive indicator of contaminant exposure in certain teleost species.     

Comparison of Sensitivity of Grasses (<Emphasis Type="Italic">Lolium perenne</Emphasis> L. and <Emphasis Type="Italic">Festuca rubra</Emphasis> L.) and Lettuce (<Emphasis Type="Italic">Lactuca sativa</Emphasis> L.) Exposed to Water Contaminated with Microcystins

The effects of aqueous extracts from Microcysts aeruginosa strains (both microcystin-producers and non-microcystin producers) on germination and root growth were investigated for three economically important plant species: Festuca rubra L., Lolium perenne L., and Lactuca sativa L. There was a clear inhibition of root growth for L. sativa exposed to strains containing microcystins (5.9–56.4 μg L⁻¹). The strain that produced the most pronounced effects contained the lowest concentration of microcystin suggesting that other cellular compounds may also affect growth.     

The Uptake of Cd,Cr, and Zn by the Macroalga <Emphasis Type="Italic">Enteromorpha crinita</Emphasis> and Subsequent Transfer to the Marine Herbivorous Rabbitfish, <Emphasis Type="Italic">Siganus canaliculatus</Emphasis>

Marine macroalgae can appreciably accumulate metals out of seawater and are the principle food source for marine herbivorous fish, thus playing an important role in introducing metals into marine food webs. There have been few experimental studies on metal transfer from macroalgae up the trophic chain. In this study, we examined the assimilation efficiencies (AEs) of Cd, Cr, and Zn in the rabbitfish, Siganus canaliculatus, which feeds on the macroalga Enteromorpha crinita. The influences of metal concentration and nutrient conditions in the macroalga, and starvation on the assimilation of metals in fish were investigated. The macroalgae were radiolabeled by direct exposure to radiotracers in the dissolved phase. The uptake of metals in the macroalgae proceeded linearly and was directly proportional to the metal concentration in the ambient seawater. Ammonium and nitrate enrichment significantly increased the accumulation of Cd by the macroalgae, whereas Cr accumulation was not influenced by nutrient enrichment. The metal concentrations in the macroalgae did not have any effect on metal assimilation in the rabbitfish. The measured AEs of the metals were generally higher in starved rabbitfish than in fed fish, probably as a result of the prolonged retention of metals in the gut of fish. Rabbitfish fed macroalgae that had been previously exposed to ammonium or nitrate addition decreased their assimilation of Cd and Zn, but not Cr. Phosphate enrichment did not have any significant effect on metal AE in the rabbitfish. Our study demonstrated that marine herbivorous fish can appreciably assimilate trace metals from marine macroalgae and that trophic transfer should be considered as a source for metal accumulation in fish. Nutrient condition and starvation do have considerable effects on the AEs of Cd and Zn in rabbitfish that are fed macroalgae. Received: 6 April 2002/Accepted: 19 August 2002     

Toxicokinetics of Organic Contaminants in <Emphasis Type="Italic">Hyalella azteca</Emphasis>

Uptake, biotransformation, and elimination rates were determined for pentachlorophenol (PCP), methyl parathion (MP), fluoranthene (FU), and 2,2′,4,4′,5,5′-hexachlorobiphenyl (HCBP) using juvenile Hyalella azteca under water-only exposures. A two-compartment model that included biotransformation described the kinetics for each chemical. The uptake clearance coefficients (k_u) were 25.7 ± 2.9, 11.5 ± 1.1, 184.4 ± 9.3, and 251.7 ± 9.0 (ml g⁻¹ h⁻¹) for PCP, MP, FU, and HCBP, respectively. The elimination rate constant of the parent compound (k_ep) for MP was almost an order of magnitude faster (0.403 ± 0.070 h⁻¹) than for PCP and FU (0.061 ± 0.034 and 0.040 ± 0.008 h⁻¹). The elimination rate constants for FU and PCP metabolites (k_em) were similar to the parent compound elimination 0.040 ± 0.005 h⁻¹ and 0.076 ± 0.012 h⁻¹, respectively. For MP, the metabolites were excreted much more slowly than the parent compound (0.021 ± 0.001 h⁻¹). For PCP, FU, and MP whose metabolites were measured, the biological half-life (t_1/2p) of the parent compound was shorter than the half-life for metabolites (t_1/2m) because the rate is driven both by elimination and biotransformation processes. Thus, H. azteca is capable of metabolizing compounds with varying chemical structures and modes of toxic action, which may complicate interpretation of toxicity and bioaccumulation results. This finding improves our understanding of H. azteca as a test organism, because most biomonitoring activities do not account for biotransformation and some metabolites can contribute significantly to the noted toxicity. Received: 13 June 2002/Accepted: 21 October 2002     

The Acute Toxicity of Gluconic Acid, β-Alaninediacetic Acid,Diethylenetriaminepentakismethylenephosphonic Acid,and Nitrilotriacetic Acid Determined by <Emphasis Type="Italic">Daphnia magna,Raphidocelis subcapitata</Emphasis>, and <Emphasis Type="Italic">Photobacterium phosphoreum</Emphasis>

Acute toxicity of four relatively new chelating agents and their equimolar manganese and cadmium complexes was studied. The chelating agents studied were gluconic acid (GA), β-alaninediacetic acid (ADA), diethylenetriaminepentakismethylenephosphonic acid (DTPMP), and nitrilotriacetic acid (NTA). Three common bioassays, namely Daphnia magna, Raphidocelis subcapitata, and Photobacterium phosphoreum (Microtox™ bioassay) were applied. R. subcapitata proved the most sensitive to these compounds. With D. magna bioassay the LC₅₀ values were 600–900 mg/L with all other studied chelates and their Mn complexes, except Mn-GA, which yielded LC₅₀ value of 240 mg/L. The Cd-chelate complexes proved highly more toxic compared to Mn-chelate complexes or uncomplexed chelates exhibiting LC₅₀ values of 130–200 μg/L. However, Cd-DTPMP was an exception exhibiting LC₅₀ value of 2170 μg/L. That is to say, DTPMP proved the strongest chelating agent to reduce the Cd toxicity in the present study. The results from these bioassays were well in agreement to each other as well as with the results published elsewhere. Received: 29 October 2001/Accepted: 19 August 2002     

Mercury Contamination in Idaho Bald Eagles, <Emphasis Type="Italic">Haliaeetus leucocephalus</Emphasis>

Because mercury contamination is potentially threatening to bald eagle (Haliaeetus leucocephalus) populations, we collected molted feathers at nests to determine the level of contamination in bald eagles in the state of Idaho, USA. Eagle feathers contained measurable amounts of cadmium (Cd), chromium (Cr), selenium (Se), lead (Pb), as well as mercury (Hg). Cadmium, Cr, Se, and Pb levels averaged 0.17, 4.68, 2.02, and 1.29 mg/kg dry weight, respectively, and were at or below concentrations indicated as causing reproductive failure in bald eagles. Mercury contamination was found to be the highest averaging 18.74 mg/kg dry weight. Although a concentration of only 7.5 mg/kg dry weight Hg in bird feathers can cause reduced productivity and even sterility, all of the eagles we sampled bred successfully and the population of bald eagles continues to grow annually throughout the state.     

Accumulation of Lead,Chromium, and Cadmium in Muscle of <Emphasis Type="Italic">capitán</Emphasis> (<Emphasis Type="Italic">Eremophilus mutisii</Emphasis>), a Catfish from the Bogota River Basin

Heavy metal accumulation of lead (Pb), chromium (Cr), and cadmium (Cd) in the muscle of the catfish Eremophilus mutisii was studied in 47 specimens, captured by anglers in the Bogotá River at two sampling sites (Chocontá and Suesca) during May–October 2005. Water samples were processed for physicochemical and metal analyses. Metal accumulation in muscle (wet weight) of specimens at Chocontá and Suesca showed high levels of Pb (3.4 and 3.1 ppm, respectively), Cr (1.8 and 2.1 ppm, respectively), and Cd (0.35 and 0.48, respectively). Metal levels in waters (ppm) indicated that average Pb (0.028 Chocontá, 0.029 Suesca), Fe (0.462 Chocontá, 1.1 Suesca), and Cr (0.113 Chocontá) were above the maximum levels (MCLs) allowed in drinking waters. No extreme average values were found for pH, nitrites, alkalinity, and hardness in the waters. This study showed the importance of benthic and nonmigratory species like the capitán to evaluate the effects of heavy metals pollution. Further public health implications could be derived in the region where this investigation took place due to consumption of capitán by people in the area.