Changes in threats to macroalgal forests (Cystoseira sensu lato) at three restoration sites in the Mediterranean Sea

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Removal of Atrazine Contamination in Soil and Liquid Systems Using Bioaugmentation

Reported levels of atrazine in soils at pesticide mix-load sites can vary between 7·9×10^-5 mM and 1·9 mM . We report on a mixed microbial culture, capable of degrading concentrations of atrazine in excess of 1·9 mM . At initial concentrations of 0·046 M and 0·23 M , the mixed population degraded 78% and 21% of atrazine in soil (100 days), respectively. At the same initial concentrations in liquid cultures, 90% and 56% of the atrazine was degraded (80 days), respectively. Decreased degradation in soil samples may have resulted from atrazine sorption to soil surfaces or decreased contact between the population and the herbicide. In the 0·23 M system, we attribute incomplete degradation to phosphorous depletion. Data for carbon dioxide evolution was fitted to a three-half-order regression model, but we feel that there are limitations of the application of this model to atrazine degradation. The population uses the herbicide as a nitrogen source and little carbon is incorporated into biomass, as the energy status of carbons in the ring leads to their direct evolution as [¹⁴C]carbon dioxide. This situation contributes to an evolution pattern that, when fitted to the three-half-order model, results in underestimation of the biomass produced. Data from our study suggest that our mixed culture could be used for bioremediation of atrazine at concentrations up to and exceeding those currently reported for agrochemical mixing-loading facilities. © 1997 SCI.     

Effects of life‐history traits on stream fish abundances across spatial scales

Identifying cross‐scale patterns of ecological processes is imperative, especially in hierarchically structured riverine ecosystems. The role of abiotic factors in determining cross‐scale spatial structure of stream fish populations and communities is well studied, but less is known about how species traits drive cross‐scale patterns. We investigated the role of species traits for explaining autocorrelation of stream fish abundance at spatial scales ranging from local stream reaches to major basins. We calculated intraclass correlation coefficients (ICCs) representing abundance autocorrelation within species (N = 47) at each of five spatial scales. A hierarchical Bayesian regression then modelled ICCs against spatial scale with the resulting regression coefficients modelled as functions of species traits. Finally, we ordinated the scale‐by‐species ICC matrix to calculate an overall metric describing species whose abundances were autocorrelated along a gradient of large to small scales, and modelled this metric as a function of species traits. Abundances of most species were autocorrelated at smaller spatial scales. Maximum fecundity had a significant positive relationship with abundance patterns across spatial scales. Species habitat affinities and body forms were significantly associated with overall abundance patterns across spatial scales: populations of upland/lotic‐affiliated species adapted to streams with high flow correlated at small (≤10 km²) spatial scales. Lowland/lacustrine species with laterally compressed bodies showed little correlation across scales. The appropriate spatial scale for modelling abundance is determined not only by exogenous (e.g. environmental) factors, but also endogenous factors, like traits. Careful consideration of traits and life history will aid researchers in designing more effective and efficient surveys and analyses.     

Comparison of proanthocyanidins in commercial antioxidants: grape seed and pine bark extracts

The major constituents in grape seed and pine bark extracts are proanthocyanidins. To evaluate material available to consumers, select lots were analyzed using high-performance liquid chromatography, gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), gel permeation chromatography (GPC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Atmospheric pressure chemical ionization (APCI) LC/MS was used to identify monomers, dimers, and trimers present. GC/MS analyses led to the identification of ethyl esters of hexadecanoic acid, linoleic acid, and oleic acid, as well as smaller phenolic and terpene components. The GPC molecular weight (MW) distribution indicated components ranging from approximately 162 to approximately 5500 MW (pine bark less than 1180 MW and grape seed approximately 1180 to approximately 5000 MW). MALDI-TOF MS analyses showed that pine bark did not contain oligomers with odd numbers of gallate units and grape seed contained oligomers with both odd and even numbers of gallate. Reflectron MALDI-TOF MS identified oligomers up to a pentamer and heptamer, and linear MALDI-TOF MS showed a mass range nearly double that of reflectron analyses.     

Application of a real time polymerase chain reaction method to detect castor toxin contamination in fluid milk and eggs

The castor seed contains ricin, which is one of the most potent biological toxins and is widely considered to be a threat agent for bioterrorism. In this study, a rapid and sensitive PCR method was applied to the detection of castor contamination in milk and liquid egg samples. The targeting gene sequence of the primer set, Ricin-F4/R4, was not found in either the bovine or chicken genome. Primers against a highly conserved sequence from the 18S ribosomal RNA gene were used as a positive control for DNA extraction and PCR reaction efficiency. The quantity and quality of DNA prepared from castor spiked or nonspiked milk and egg samples obtained from three different DNA extraction methods were compared. The cetyl trimethylammonium bromide (CTAB) method yielded the highest quality of DNA and is most suitable for the sensitive detection of castor DNA by real-time PCR in both milk and liquid egg matrixes. However, taking time and cost into consideration, a commercial kit designed for extraction of DNA from stool samples could be used as an alternative method for the routine extraction of DNA from milk for real-time PCR assays. The egg matrix was found to inhibit PCR amplification and interfere with two of the three methods tested for DNA extraction. Egg yolk had a greater negative effect on PCR amplification than the egg white matrix. Our results affirm the necessity of performing individual validations for each food matrix. Both real-time PCR systems used in this study, TaqMan and SYBR Green I dye, were capable of detecting 100 ng of castor acetone powder, corresponding to 5 ng of ricin, in 1 mL of milk or liquid egg, well below the toxic dose for humans. On the basis of these results, the real-time PCR method for detection of intentional castor contamination is applicable to milk and egg matrixes.     

Effects of platelet-derived growth factor-BB on the metabolic function and morphologic features of equine tendon in explant culture

OBJECTIVE: To evaluate the effects of recombinant human platelet-derived growth factor-BB (rhPDGF-BB) on the metabolic function and morphologic features of equine superficial digital flexor tendon (SDFT) in explant culture. Animals-6 euthanized horses (2 to 5 years old). METHODS: Forelimb SDFT explants were cultured for 6 days as untreated control specimens or treated with rhPDGF-BB (1, 10, 50, or 100 ng/mL of medium). Treatment effects on explant gene expression were evaluated via real-time PCR analysis of collagen type I, collagen type III, PDGF-A, and PDGF-B mRNA. Explants were assayed for total collagen, glycosaminoglycan, and DNA content; histologic changes were assessed via H and E staining and immunohistochemical localization of collagen types I and III. RESULTS: No morphologic or proliferative changes were detected in tendon explant sections. After high-dose rhPDGF-BB treatment, gene expression of collagen types I and III was increased and decreased, respectively. Expression of PDGF-A and PDGF-B mRNA was significantly increased at 24 hours, but later decreased to have few or negative autoinductive effects. Although PDGF gene expression waned after 48 hours of culture, collagen type I gene expression was significantly increased at 48 hours and reached peak value on day 6. Glycosaminoglycan and DNA content of explants were unchanged with rhPDGF-BB treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that rhPDGF-BB use may be of benefit in the repair of equine tendon, particularly through induction of collagen type I mRNA. Positive autoinductive effects of PDGF-BB in equine SDFT explants were detected early following culture medium supplementation, but these diminished with time.     

The molecular diversity of adaptive convergence

To estimate the number and diversity of beneficial mutations, we experimentally evolved 115 populations of Escherichia coli to 42.2°C for 2000 generations and sequenced one genome from each population. We identified 1331 total mutations, affecting more than 600 different sites. Few mutations were shared among replicates, but a strong pattern of convergence emerged at the level of genes, operons, and functional complexes. Our experiment uncovered a set of primary functional targets of high temperature, but we estimate that many other beneficial mutations could contribute to similar adaptive outcomes. We inferred the pervasive presence of epistasis among beneficial mutations, which shaped adaptive trajectories into at least two distinct pathways involving mutations either in the RNA polymerase complex or the termination factor rho.     

“The Range Problem” After a Century of Rangeland Science: New Research Themes for Altered Landscapes

The rangeland science profession in the United States has its roots in the widespread overgrazing and concurrent severe droughts of the late 19th century. These drivers contributed to rangeland resource degradation especially in the American Southwest—what E. O. Wooton (1908) called the “Range Problem.” Although logical for the time, the scientific activities and resulting policies that arose out of this catastrophe were based on reductionist experimentation and productionist emphases on food and fiber. After a century of science and policy, there are two additional perspectives that shape our vision for the emphases of the future. First, rangeland landscapes are extremely heterogeneous; general principles derived from scientific experimentation cannot be easily or generally applied without adjusting to the distinct societal and ecological characteristics of a location. Second, rangeland management occurs at spatial scales considerably larger than those that have typically been addressed in range science. Scaling up science results is not a simple, additive process. The leading features of the emerging science are 1) research at landscape scales and 2) over longer time spans that 3) approaches conservation and management practices as treatments requiring scientific evaluation, 4) incorporates local knowledge, 5) is explicitly applied in nature, and 6) is transparent in its practice. We strongly argue for a science that supports resource management by testing hypotheses relevant to actual conservation practices and iteratively applying its findings in partnership with managers in an ongoing, adaptive fashion.     

Grand Challenges for Resilience-Based Management of Rangelands

The social and ecological contexts for rangeland management are changing rapidly, prompting a reevaluation of science, management, and their relationship. We argue that progression from steady-state management to ecosystem management has served the rangeland profession well, but that further development toward resilience-based management is required to ensure that ecosystem services are sustained in an era of rapid change. Resilience-based management embraces the inevitability of change and emphasizes that management should seek to guide change to benefit society. The objectives of this forum are to: 1) justify the need for adopting resilience-based management, 2) identify the challenges that will be encountered in its development and implementation, and 3) highlight approaches to overcoming these challenges. Five grand challenges confronting the adoption of resilience-based management, based upon the insights of 56 rangeland researchers who have contributed to this special issue, were identified as: 1) development of knowledge systems to support resilience-based management, 2) improvement of ecological models supporting science and management, 3) protocols to assess and manage tradeoffs among ecosystem services, 4) use of social-ecological system models to integrate diverse knowledge sources, and 5) reorganization of institutions to support resilience-based management. Resolving the challenges presented here will require the creation of stronger partnerships between ecosystem managers, science organizations, management agencies, and policymakers at local, regional, and national scales. A realistic near-term goal for achieving such partnerships is to initiate and support collaborative landscape projects. The creation of multiscaled social learning institutions linked to evolving knowledge systems may be the best approach to guide adaptation and transformation in rangelands in the coming century.