Synthesis of polychlorinated biphenyls and their metabolites with a modified Suzuki-coupling

A modified procedure for the synthesis of polychlorinated biphenyls (PCBs) utilizing the Suzuki-coupling, a palladium-catalyzed cross-coupling reaction, is described. The coupling of (chlorinated) benzene boronic acids with bromochlorobenzenes, using Pd(dppf)(2)Cl(2) (dppf = 1,1'-bis(diphenylphosphino)ferrocene) as the catalyst and aqueous sodium carbonate as the base, gave the desired PCB congeners in moderate to good yields. Eleven PCB congeners, including environmentally important PCB congeners and metabolites, were synthesized using this modified procedure. This new catalyst Pd(dppf)(2)Cl(2) offers the advantage of being less air-sensitive and has a longer shelf life compared to Pd(PPh(4))(4). Three new (di-)methoxylated PCB congeners were synthesized using the same procedure by either coupling a chlorinated benzene boronic acid with a bromo (di-)methoxybenzene or by coupling a (di-)methoxy benzene boronic acid with a chlorinated bromobenzene. The dimethoxylated PCB congeners were readily converted into the respective dihydroxylated PCB derivatives using boron tribromide in dichloromethane. This approach offers the advantage of high selectivity and moderate to good yields compared to conventional methods such as the Cadogan reaction and allows the use of less toxic starting materials.     

Biosensor-based diagnostics of contaminated groundwater: assessment and remediation strategy

Shallow groundwater beneath a former airfield site in southern England has been heavily contaminated with a wide range of chlorinated solvents. The feasibility of using bacterial biosensors to complement chemical analysis and enable cost-effective, and focussed sampling has been assessed as part of a site evaluation programme. Five different biosensors, three metabolic (Vibrio fischeri, Pseudomonas fluorescens 10568 and Escherichia coli HB101) and two catabolic (Pseudomonas putida TVA8 and E. coli DH5alpha), were employed to identify areas where the availability and toxicity of pollutants is of most immediate environmental concern. The biosensors used showed different sensitivities to each other and to the groundwater samples tested. There was generally a good agreement with chemical analyses. The potential efficacy of remediation strategies was explored by coupling sample manipulation to biosensor tests. Manipulation involved sparging and charcoal treatment procedures to simulate remediative engineering solutions. Sparging was sufficient at most locations.     

Differences in kelp morphology between wave sheltered and exposed localities: morphologically plastic or fixed traits?

The ability of algae to change the shape of their thallus in response to the environment may be of functional and ecological importance to the alga, with many species of macroalgae exhibiting a great range of morphological variation across wave exposure gradients. However, differences in morphology detected between sheltered and exposed environments cannot determine whether such differences represent plastic responses to the local environment or whether morphology is genetically fixed. This study tested for differences in the morphology of the common kelp, Ecklonia radiata, between wave sheltered and exposed environments, and reciprocally transplanted juveniles to distinguish the nature of such differences (i.e. plastic vs fixed traits). Differences between exposure environments were consistent with known effects of exposure (i.e. a wide, thin thallus at sheltered sites and a narrow, thick thallus with a thick stipe at exposed sites). The reciprocal transplant experiment confirmed that morphological plasticity was the mechanism enabling this alga to display different patterns in morphology between exposure environments. Individuals transplanted to the exposed environment underwent a rapid and extreme response in morphology, which was not apparent in individuals transplanted to the sheltered environment that responded more slowly. These results suggest that stressors typical of sheltered environments (i.e. diffusion stress) may not be as influential (if at all) compared to stressors typical of exposed environments (i.e. breakage, dislodgement) in differentiating morphological characters between exposure environments.     

Assured fitness returns favor sociality in a mass-provisioning sweat bee,Megalopta genalis (Hymenoptera: Halictidae)

Assured fitness returns models for the evolution of sociality emphasize the selective value of ensuring that offspring receive adequate parental care to reach maturity. If a member of a social group dies, it can accrue returns on investment in offspring through the efforts of surviving social partners. We provide evidence that in the mass-provisioning, facultatively social sweat bee Megalopta genalis, adult presence in the nest throughout brood development provides protection from ant predation. Nests with adults present were well protected, and brood in nests with adults removed suffered higher predation. Females in observation nests showed effective defensive behavior against experimentally introduced ants, and bees in natural nests repulsed naturally occurring ant raids. Megalopta nest architecture and behavior are such that the brood of several cooperating females can be defended with little additional cost relative to solitary nesting. The benefits of cooperative defense may favor group living in mass provisioning bees. Our observations and experiments suggest that parental care throughout brood development can be adaptive in mass provisioning species, supporting the predictions of assured fitness returns models.     

Experimental analysis of worker division of labor in bumblebee nest thermoregulation (<Emphasis Type="Italic">Bombus huntii</Emphasis>, Hymenoptera: Apidae)

Bumblebee colonies experience daily and seasonal fluctuations in ambient temperature, but proper brood development requires a stable nest temperature. This study examined how adaptive colony responses to changing ambient temperature are achieved through the in-nest workers’ behavioral plasticity. We studied three Bombus huntii colonies in the laboratory. In the first experiment, we manipulated ambient temperature and recorded brood cell incubation and wing fanning by individually marked, known-age bees. The colonies maintained their nests closer to appropriate brood development temperatures (28 to 32°C) when exposed to a range of ambient temperatures from 10.3 to 38.6°C. Incubation activity was greater in cooler treatment conditions, whereas in the highest temperature treatment, some bees fanned and others moved off the brood. As the ambient temperature dropped, workers increased the duration of their incubating bouts, but, except at the highest temperature, the number of workers that incubated did not differ significantly among treatments. A subset of the bees incubated significantly more than their nest mates, some of which never incubated. Worker body size, but not age, was a good predictor of incubation rates, and smaller bees incubated at higher rates. In the second experiment, we removed the most actively incubating workers. Immediately after removals, the total colony incubation effort was lower than pre-removal levels, but incubation effort rebounded toward pre-removal levels after 24 h. The increased thermoregulatory demand after removals was met primarily by bees increasing their rates of incubation rather than by bees switching from a different task to incubation. We conclude that some B. huntii workers specialize on nest thermoregulation, and that changes in work rates are more important than task switching in meeting thermal challenges.     

Interlaboratory comparability of copper complexation capacity determination in natural waters

The results of a test of interlaboratory comparability for the determination of copper complexation capacity and copper-ligand complex formation constant are presented. Eight water samples comprising, six natural waters, a synthetic ligand solution and a blank solution were analysed by seven laboratories using their own methods of complexation titration. Given the wide variation that might have been possible, relatively good comparability was demonstrated amongst the variety of methods for determining copper complexation capacity. The complexation capacity data largely satisfied the predefined criterion of agreement to within 50%. This provides support for the use of metal speciation criteria in the regulation of copper in the environment. Data for the determination of complex formation constants were of poorer comparability, ranging between 10(7) and 10(12) for the same water.     

Cloud water and throughfall deposition of mercury and trace elements in a high elevation spruce-fir forest at Mt. Mansfield,Vermont

As part of the Lake Champlain Basin watershed study of mercury (Hg) and pollutant deposition, cloud water and cloud throughfall collections were conducted at the south summit (1204 m) of Mt. Mansfield, Vermont between August 1 and October 31, 1998, for multi-element chemical analysis. A passive Teflon string collector was deployed during non-precipitating events to sample cloud/fog water at timberline, while three sets of paired funnels collected cloud throughfall under the red spruce-balsam fir canopy. Samples were analyzed for concentrations of Hg, major ions, and 10 trace elements. Ultra-clean sampling and analysis techniques were utilized throughout the study. Six events were sampled for cloud water alone and four events were sampled for both cloud water and cloud throughfall. Cloud throughfall chemistry showed substantial modification from incident cloud water. Much higher concentrations of Hg (2.3 x), base cations (Ca2+, K-, Mg2+; 3-18 x) and certain trace elements (Ni, Cu, Mn, Rb, Sr; 2-34 x) were observed in throughfall than in cloud water. These results confirm that cloud water can leach a wide variety of elements from tree foliage and wash off dry deposited elements. Cloud water deposited an average of 0.42 +/- 0.12 mm of water per hour. Estimated cloud water deposition of Hg was 7.4 microg m(-2) for the period August 1-October 31, approximately twice that deposited by rain during this period at a nearby low elevation Hg monitoring site. Our results indicate that cloud water and Hg deposition at Mt. Mansfield are likely to have considerable ecological effects.     

Effects of Turbidity,Sediment, and Polyacrylamide on Native Freshwater Mussels

Turbidity is a ubiquitous pollutant adversely affecting water quality and aquatic life in waterways globally. Anionic polyacrylamide (PAM) is widely used as an effective chemical flocculent to reduce suspended sediment (SS) and turbidity. However, no information exists on the toxicity of PAM‐flocculated sediments to imperiled, but ecologically important, freshwater mussels (Unionidae). Thus, we conducted acute (96 h) and chronic (24 day) laboratory tests with juvenile fatmucket (Lampsilis siliquoidea) and three exposure conditions (nonflocculated settled sediment, SS, and PAM‐flocculated settled sediment) over a range of turbidity levels (50, 250, 1,250, and 3,500 nephelometric turbidity units). Survival and sublethal endpoints of protein oxidation, adenosine triphosphate (ATP) production, and protein concentration were used as measures of toxicity. We found no effect of turbidity levels or exposure condition on mussel survival in acute or chronic tests. However, we found significant reductions in protein concentration, ATP production, and oxidized proteins in mussels acutely exposed to the SS condition, which required water movement to maintain sediment in suspension, indicating responses that are symptoms of physiological stress. Our results suggest anionic PAM applied to reduce SS may minimize adverse effects of short‐term turbidity exposure on juvenile freshwater mussels without eliciting additional lethal or sublethal toxicity.     

Minimizing Harm in Possum Control Operations and Experiments in New Zealand

Pest control operations andexperimentation on sentient animals such as thebrushtail possum can cause unnecessary andavoidable suffering in the animal subjects.Minimizing animal suffering is an animalwelfare goal and can be used as a guide in thedesign and execution of animal experimentationand pest control operations.The public has little sympathy for the possum,which can cause widespread environmentaldamage, but does believe that control should beas painless as possible. Trapping and poisoningprovide only short-term solutions to the possumproblem and often involve methods that causesuffering. Intrusive experiments connected withthese methods of control and published in thelast 6 years are reviewed. Many of theexperiments do not attain the welfare standardsrequired by members of the public.Possums also act as vectors for bovinetuberculosis. While this is not as important inthe minds of the public as environmentaldegradation, as long as people wish to continueraising cattle, this disease needs to becontrolled.Immunocontraception is a humane means ofcontrolling possums with wide publicacceptance. The use of vaccines for cows and/orpossums would also cause far less sufferingthan present eradication operations. Researchinto these methods does require some intrusiveexperimentation. This can be reduced if liveanimals are not used for secondary antibodyharvesting, if adequate analgesia is provided,and if potential vaccines or contraceptives aretested under conditions that would beexperienced in the field.     

Osteomyelitis in a Paleozoic reptile: ancient evidence for bacterial infection and its evolutionary significance

We report on dental and mandibular pathology in Labidosaurus hamatus, a 275 million-year-old terrestrial reptile from North America and associate it with bacterial infection in an organism that is characterized by reduced tooth replacement. Analysis of the surface and internal mandibular structure using mechanical and CT-scanning techniques permits the reconstruction of events that led to the pathology and the possible death of the individual. The infection probably occurred as a result of prolonged exposure of the dental pulp cavity to oral bacteria, and this exposure was caused by injury to the tooth in an animal that is characterized by reduced tooth replacement cycles. In these early reptiles, the reduction in tooth replacement is an evolutionary innovation associated with strong implantation and increased oral processing. The dental abscess observed in L. hamatus, the oldest known infection in a terrestrial vertebrate, provides clear evidence of the ancient association between terrestrial vertebrates and their oral bacteria.