Prey‐type‐dependent foraging of young‐of‐the‐year fish in turbid and humic environments

Abstract – Fish, which are generally visual foragers, experiences reduced reaction distance in visually degraded environments, which has consequences for encounter rates with prey. Small prey is detected at shorter distances than larger prey, and piscivores are therefore predicted to be more strongly affected by visual degradation. In experiments, roach (Rutilus rutilus) were fed two plankton prey types and pike (Esox lucius) were fed Daphnia and larval roach, in clear water, algal turbid water and water coloured brown by dissolved organic matter (DOM). Planktivorous foraging in roach was not affected by visual degradation, while pike foraging on both Daphnia and larval roach was. Pike showed increased reaction distance to Daphnia in visually degraded water, while it was severely reduced with roach as prey even if the visual range was not reduced below pike reaction distances in clear water. Pike foraging on Daphnia was not affected, but when foraging on roach, the reduced search efficiency was counteracted by increased attack rates. However, there was no increase in movement and no difference between turbid and DOM treatments. Effects on piscivores will likely become more pronounced at later life stages as prey size and the reliance on long‐distance detection increases at the same time as changing climatic conditions may further deteriorate the visual conditions in future.     

Prevalence and geographic distribution of Fanconi syndrome in Basenjis in the United States

A survey was conducted to ascertain the prevalence of Fanconi syndrome in Basenjis and to determine in which geographic regions the greatest number of affected dogs resided. A thousand questionnaires were distributed nationally, and 624 (62%) were returned. Through this survey, prevalence, geographic distribution, and breeder involvement were successfully correlated with the overall association of the disease with the Basenji breed. Ten percent (96/959) of all Basenjis involved in the survey had Fanconi syndrome. Half (50%; 48/96) of the Basenjis affected were between 4 and 8 years old. Seventy-six percent (44/58) of owners of Basenjis with Fanconi syndrome were breeding their dogs, and 93% (52/56) had owned other Basenjis before the survey was conducted. Females outnumbered males (3:1) in frequency of the disease. This ratio reflected the higher breeder participation in the survey, rather than being a true gender predilection for the disease.     

Epidemiology of neoplasia in captive black-footed ferrets (Mustela nigripes), 1986-1996.

The epidemiology of neoplastic disease was studied retrospectively in the captive population of black-footed ferrets (Mustela nigripes). Postmortem reports were reviewed and archived tissues examined from 184 of the 227 adult (>1 yr old) black-footed ferrets that died from the beginning of the current captive propagation program in late 1985 to the end of 1996. A total of 185 neoplasms, of 28 distinct phenotypes, were seen in 102 (55.4%) of these ferrets. There was more than one tumor type present in 51 ferrets. Tumors of the apocrine glands (28.3%), renal tubular neoplasms (20.7%), and biliary cystadenoma or carcinoma (20.1%) were the most common neoplasms. The probability of developing most types of neoplasms increased with age. Neoplasms of the apocrine glands were more common in males and may be hormonally influenced. The unusually high prevalence of biliary cystadenocarcinoma may be secondary to the common occurrence of intrahepatic biliary cysts in this population. Although neoplasia is an important cause of mortality in captive adult black-footed ferrets, its impact on captive propagation of the species, and on the wild population, is probably limited because clinically significant tumors are encountered almost exclusively in postreproductive ferrets (>3 yr old) and because ferrets released into their natural habitat rarely reach susceptible age.     

Effects-based Assays in the Earthworm Aporrectodea caliginosa: Their Utilisation for Evaluation of Contaminated Sites before and after Remediation (8 pp)

Goal, Scope and Background   In a preliminary ecological risk assessment, potential adverse effects of contaminants are often evaluated by measuring chemical residues and comparing these with regulatory guidelines. However limitations with this approach with regards to establishing actual effects have resulted in the increasing usage of sublethal effects-based assays, including biomarkers, to evaluate the hazard posed by contaminants in the environment. In this study a number of effects-based endpoints in the earthworm Aporrectodea caliginosa were evaluated to determine their comparative sensitivity for assessment of adverse effects of soil contaminated with petroleum hydrocarbons. Methods   Adult and juvenile earthworms were exposed for 4 weeks to sublethal concentrations of soil collected before and after remediation of a petroleum-contaminated site. A suite of endpoints were measured in these earthworms, including mortality, fecundity, growth, and juvenile maturation, and two less traditional endpoints, the biomarker, the neutral red retention assay (NRRA) and an avoidance behaviour test. Results and Discussion   Cocoon viability in this species is not a reliable parameter to measure, due to low viability in controls and a high coefficient of variation. Growth in adult earthworms was a more sensitive parameter than cocoon production. Maturation and growth of juveniles have been proposed as more sensitive endpoints than adult cocoon production and growth respectively. This was not apparent in the growth parameters, but maturation of juveniles did appear to be more sensitive than cocoon production by adults. The NRRA was a more sensitive parameter than cocoon production, and the NRRA and growth were both affected at the lowest concentration tested. The NRRA response appeared to be more sensitive than growth, but NRRT was only evaluated in one soil only, while the other parameters were assessed in two soils. However, the NRRA has previously been found to be more sensitive than growth after exposure to a number of contaminants. The avoidance behaviour assay exhibited similar sensitivity to growth and fecundity and could therefore be useful as a simple pre-screening test. Conclusion   The chronic endpoints, growth, cocoon production, and juvenile maturation parameters, were all sensitive endpoints for detecting exposure to the petroleum-hydrocarbon-contaminated soil. The NRRA was the most sensitive of the endpoints assessed and could be used as an early-warning indicator to predict adverse impacts. Avoidance behaviour could be used as a simple pre-screening test to evaluate contaminated soils prior to more extensive and invasive testing. Recommendations and Perspective   Measuring chemical concentrations in environmental samples is not always useful, as the toxicological impacts of exposure to these concentrations are not always discernible. However, the use of effects-based endpoints, either in situ or in the laboratory using laboratory-reared earthworms, can account for the bioavailability of chemicals in the soil, and can therefore provide information on the toxicological impacts of exposure. The assays tested in this research were sensitive indicators of exposure, and therefore can be used to determine potential ecological risks at contaminated sites and to monitor the progress of remediation at these sites.     

Light Weight Aggregates made from Dredged Harbour Sediments

Goal  

Annually, 400.000 m₃ harbour sediments are dredged to maintain the water depth in the harbours of Bremen and Bremerhaven. The sediment contains organic and inorganic pollutants and hence is deposited on a landfill. Because of the limited capacity of that landfill alternative treatment techniques are investigated. This study aims to evaluate the production of Light Weight Aggregates (LWA) from harbour sediments with respect to the product quality and environmental aspects of the use of the LWA.     

Using EM and VERIS technology to assess land suitability for orchard and vineyard development

Orchard and vineyard producers conduct preplant site evaluations to help prevent planting permanent tree and vine crops on lands where the crop will not perform to its highest potential or attain its full life expectancy. Physical soil characteristics within specific soil profiles and spatially throughout an orchard influence decisions on land preparation, irrigation system selection, horticultural choices, and nutrient management. Producers depend on soil surveys to help them understand the soil characteristics of the land and may be interested in technology that provides additional information. Electromagnetic induction (EM38) and four-probe soil resistance sensors (VERIS) are being used in combination with global positioning systems to map spatial variability of soils using apparent soil electrical conductivity (ECa). The hypothesis evaluated in this study is whether rapid, in situ, and relatively low-cost methods of measuring ECa (EM38 and VERIS) can effectively identify and map physical soil variability in non-saline soils. The supposition is that in non-saline soils, ECa levels will relate well to soil texture and water-holding capacity and can be used to map physical soil variability. In turn, the information can be used to guide decisions on preplant tillage, irrigation system design, water and nutritional management, and other horticultural considerations. Two sites in the Sacramento Valley were mapped each with EM38 and VERIS methods. Site-specific management zones were identified by each provider on ECa maps for each site, and then soil samples were collected by University of California researchers to verify these zones. Results showed that on non-saline soils, ECa measured with both EM38 and VERIS correlate with physical soil properties such as gravel, sand, silt, and clay content but the relationship between conductivity and these physical soil properties varied from moderately strong to weak. The strength of the correlation may be affected by several factors including how dominant soil texture is on conductivity relative to other soil properties and on methods of equipment operation, data analysis and interpretation. Overall, the commercial providers of ECa surveys in this study delivered reasonable levels of accuracy that were consistent with results reported in previous studies. At one site, an ECa map developed with VERIS provided more detail on physical soil variability to supplement published soil surveys and aided in the planning and development of a walnut orchard. At a second site, almond yield appeared to correlate well with distinctly different soil zones identified with EM38 mapping.     

Temporal bone preservation in a 2600-year-old Egyptian mummy

Perforated eardrums in the preserved temporal bones of a mummified Egyptian male in otherwise normal middle ears offer new evidence of acute otitis media and probable defective hearing among ancient Egyptians.     

Structural basis of type II topoisomerase inhibition by the anticancer drug etoposide

Type II topoisomerases (TOP2s) resolve the topological problems of DNA by transiently cleaving both strands of a DNA duplex to form a cleavage complex through which another DNA segment can be transported. Several widely prescribed anticancer drugs increase the population of TOP2 cleavage complex, which leads to TOP2-mediated chromosome DNA breakage and death of cancer cells. We present the crystal structure of a large fragment of human TOP2β complexed to DNA and to the anticancer drug etoposide to reveal structural details of drug-induced stabilization of a cleavage complex. The interplay between the protein, the DNA, and the drug explains the structure-activity relations of etoposide derivatives and the molecular basis of drug-resistant mutations. The analysis of protein-drug interactions provides information applicable for developing an isoform-specific TOP2-targeting strategy.