Storage and metabolism of radioactively labeled pyrrolizidine alkaloids by butterflies and larvae of Mechanitis polymnia (Lepidoptera: Nymphalidae,Ithomiinae)

Summary. Tracer feeding studies with radioactively labeled pyrrolizidine alkaloids (PAs) were performed to attain experimental information about the specificity and mechanisms of uptake, metabolism and storage of PAs in the alkaloid sequestering ithomiine butterfly Mechanitis polymnia. Adult butterflies easily ingest the tracers offered dissolved in a saturated sugar solution. Feeding of [¹⁴C]rinderine (free base) confirmed that M. polymnia is well adapted to sequester and maintain PAs of the lycopsamine type. Approximately 80% of the ingested radioactivity can be recovered in methanol extracts of the butterflies over a period of at least 6 hours. Labeled rinderine is efficiently N-oxidized and transformed into a metabolite of still unknown structure. These two metabolites are formed in almost equal amounts and account for more than 90% of total radioactivity. After four hours the toxic free base is only detectable in traces. Radioactively labeled senecioylretronecine (free base), a PA that often accompanies PAs of the lycopsamine type in plants, is metabolized in a different manner. The toxic free base disappeared as fast as the tertiary rinderine, but the final products which accumulated in a stable ratio after 12 hours were mainly two polar metabolites of unknown structure; senecioylretronecine N-oxide accounts for less than 10% of total PAs. Labeled senecionine a macrocyclic PA, which never has been found in wild caught M. polymnia is only slowly N-oxidized. In females ca 50% of the ingested senecionine is still present as free base after 24 hours, whereas under the same conditions in males this percentage is only ca 20%. This difference in N-oxidation was the only significant sex-specific difference observed in various experiments. Larvae of M. polymnia which feed on Solanum tabacifolium, a plant that does not contain PAs, are able to sequester and partly N-oxidize labeled senecioylretronecine and senecionine. However, the storage is not very efficient; with the two tracers less than 5% of radioactivity remained in the bodies after 24 hours. Received 19 October 1999; accepted 24 November 1999     

Equity trade‐offs in conservation decision making

Conservation decisions increasingly involve multiple environmental and social objectives, which result in complex decision contexts with high potential for trade‐offs. Improving social equity is one such objective that is often considered an enabler of successful outcomes and a virtuous ideal in itself. Despite its idealized importance in conservation policy, social equity is often highly simplified or ill‐defined and is applied uncritically. What constitutes equitable outcomes and processes is highly normative and subject to ethical deliberation. Different ethical frameworks may lead to different conceptions of equity through alternative perspectives of what is good or right. This can lead to different and potentially conflicting equity objectives in practice. We promote a more transparent, nuanced, and pluralistic conceptualization of equity in conservation decision making that particularly recognizes where multidimensional equity objectives may conflict. To help identify and mitigate ethical conflicts and avoid cases of good intentions producing bad outcomes, we encourage a more analytical incorporation of equity into conservation decision making particularly during mechanistic integration of equity objectives. We recommend that in conservation planning motivations and objectives for equity be made explicit within the problem context, methods used to incorporate equity objectives be applied with respect to stated objectives, and, should objectives dictate, evaluation of equity outcomes and adaptation of strategies be employed during policy implementation.     

Starch-Based Materials Encapsulating Anthocyanins: A Review

Journal of Polymers and the Environment - Anthocyanins (ACNs) are natural pigments broadly used in the food industry due to their color, antioxidant, and antimicrobial properties, however, these...     

Assessing conservation status with extensive but low-resolution data: Application of frequentist and Bayesian models to endangered Athabasca River rainbow trout

Use of extensive but low-resolution abundance data is common in the assessment of species at-risk status based on quantitative decline criteria under International Union for Conservation of Nature (IUCN) and national endangered species legislation. Such data can be problematic for 3 reasons. First, statistical power to reject the null hypothesis of no change is often low because of small sample size and high sampling uncertainty leading to a high frequency of type II errors. Second, range-wide assessments composed of multiple site-specific observations do not effectively weight site-specific trends into global trends. Third, uncertainty in site-specific temporal trends and relative abundance are not propagated at the appropriate spatial scale. A common result is the propensity to underestimate the magnitude of declines and therefore fail to identify the appropriate at-risk status for a species. We used 3 statistical approaches, from simple to more complex, to estimate temporal decline rates for a designatable unit (DU) of rainbow trout in the Athabasca River watershed in western Canada. This DU is considered a native species for purposes of listing because of its genetic composition characterized as >0.95 indigenous origin in the face of continuing introgressive hybridization with introduced populations in the watershed. Analysis of abundance trends from 57 time series with a fixed-effects model identified 33 sites with negative trends, but only 2 were statistically significant. By contrast, a hierarchical linear mixed model weighted by site-specific abundance provided a DU-wide decline estimate of 16.4% per year and a 3-generation decline of 93.2%. A hierarchical Bayesian mixed model yielded a similar 3-generation decline trend of 91.3% and the posterior distribution showed that the estimate had a >99% probability of exceeding thresholds for an endangered listing. We conclude that the Bayesian approach was the most useful because it provided a probabilistic statement of threshold exceedance in support of an at-risk status recommendation.     

Methods for selenium removal from contaminated waters: a review

Environmental Chemistry Letters - Worldwide contamination of waters by metals, metalloids, and organometallic pollutants is a major health issue. In particular, the occurrence of the selenium...