Speciation and carcinogenic classification—some limits of assessment and prevention procedures—the case of “nickel”

The speciation of nickel is of the highest importance for the definition of lists of substances for regulatory activity in terms of prevention, regarding possible cancer risk. A review is made of the different attitudes of outstanding administrations in front of nickel speciation. Some of them show a maximum of care in chemical definition, others reflect a lack of scientific rigor leading to generic classifications, more or less abusive. The great complexity of the chemistry and physicochemistry of nickel imposes the “two‐level speciation concept” (chemical and physicochemical), at least for compliance with the “Good Laboratory Practice” as far as experimental toxicology is concerned. Recommendations are exposed for the attention of toxicologists and regulators who have been for some years now extremely solicited for prevention aims.     

14C标记的月桂酸盐在淡水勾虾（Hyalella azteca）中的生物富集、代谢及空间分布

对水的生物蓄积性监管评估通常是基于鱼类流水暴露试验得出生物浓缩因子（BCF）。这样的实验需要很多实验动物,而且费时费钱。最近,有人提出了一种替代性的有机中性化合物的测试方法,即用勾虾（Hyalella azteca）进行测试得到BCF值,该值与鱼类 BCF值有很强的相关性。本文研究了离子化合物月桂酸盐在H. azteca中的生物浓缩潜力。采用流动和半静态的方法对勾虾H. azteca进行1-14C-月桂酸钠暴露实验。由于该化合物的生物降解速度快,需要采用半静态方法,即频繁更换介质,以确保介质浓度稳定。月桂酸盐也可被H. azteca快速代谢。在勾虾组织中测得的总放射性中有很大一部分是不能提取的,这表明矿化月桂酸盐富集在H. azteca的钙化外骨骼中。这在使用14C标记的碳酸盐的进一步研究中得到了证实。以游离脂肪酸计量,月桂酸盐的脂质标准化（5.0%）的勾虾 BCF为8.9。H. azteca的生物浓缩研究结果证实了先前在鱼类中观察到的试验项目的低生物富集潜力。然而,需要测试更多的具有不同性质的有机离子化合物,以评估鱼和勾虾的BCF数据之间是否存在一般相关性。     

Factors driving mortality and growth at treeline: a 30-year experiment of 92 000 conifers

Understanding the interplay between environmental factors contributing to treeline formation and how these factors influence different life stages remains a major research challenge. We used an afforestation experiment including 92 000 trees to investigate the spatial and temporal dynamics of tree mortality and growth at treeline in the Swiss Alps. Seedlings of three high-elevation conifer species (Larix decidua, Pinus mugo ssp. uncinata, and Pinus cembra) were systematically planted along an altitudinal gradient at and above the current treeline (2075 to 2230 m above sea level [a.s.l.]) in 1975 and closely monitored during the following 30 years. We used decision-tree models and generalized additive models to identify patterns in mortality and growth along gradients in elevation, snow duration, wind speed, and solar radiation, and to quantify interactions between the different variables. For all three species, snowmelt date was always the most important environmental factor influencing mortality, and elevation was always the most important factor for growth over the entire period studied. Individuals of all species survived at the highest point of the afforestation for more than 30 years, although mortality was greater above 2160 m a.s.l., 50-100 m above the current treeline. Optimal conditions for height growth differed from those for survival in all three species: early snowmelt (ca. day of year 125-140 [where day 1 is 1 January]) yielded lowest mortality rates, but relatively later snowmelt (ca. day 145-150) yielded highest growth rates. Although snowmelt and elevation were important throughout all life stages of the trees, the importance of radiation decreased over time and that of wind speed increased. Our findings provide experimental evidence that tree survival and height growth require different environmental conditions and that even small changes in the duration of snow cover, in addition to changes in temperature, can strongly impact tree survival and growth patterns at treeline. Further, our results show that the relative importance of different environmental variables for tree seedlings changes during the juvenile phase as they grow taller.     

Ein Ansatz zur Methodik der vergleichenden Bewertung von Bodenbelastungen

An evaluation of the degradation of soils can be performed in several ways. Here, one way will be demonstrated beginning with the definition of the objects which are to be evaluated, continued with the definition of protection aims and the derivation of indicators. Objects together with indicators provide the frame within which a multicriteria assessment, has to be performed. Often no deterministic quality function is available, so that the concept of partially ordered sets is suggested. This concept is demonstrated by an example of an evaluation exercise performed for the environmental protection agency in Baden Württemberg. A result is that the use of arbitrarily defined quality functions may lead to erroneous statements.     

Phylogenetic relationships of coral-associated gobies (Teleostei,Gobiidae) from the Red Sea based on mitochondrial DNA data

Bryaninops, Gobiodon, Paragobiodon and Pleurosicya are the most abundant genera of coral-associated gobies. These genera are adapted to live among coral, while other small reef gobies (e.g., the genus Eviota) show no obligate association with this living substrate. Thirteen coral-associated species and two Eviota species were sampled from different regions of the Red Sea, along with four populations/species of Gobiodon from the Indian and western Pacific Oceans. A molecular phylogenetic analysis was performed using partial sequences of 12S rRNA, 16S rRNA and cytochrome b mitochondrial genes, 1,199 base pairs in total. Several clades were consistently resolved in neighbor joining-, maximum parsimony-, maximum likelihood and Bayesian analyses. While each of the four genera Gobiodon, Paragobiodon, Bryaninops and Pleurosicya proved to be monophyletic, their relative position in the phylogeny did not support an emergence of coral-associated gobiids as a monophyletic assemblage. Instead, two separate monophyletic sub-groups were discovered, the first comprising Gobiodon and Paragobiodon, and the second Bryaninops and Pleurosicya. Our molecular phylogenetic examinations also revealed one unassigned species of Gobiodon from the Maldives as a distinct species and confirmed three putative and yet unassigned species from the Red Sea. Moreover, the uniformly black colored species of Gobiodon are not monophyletic but have evolved independently within two distinct species groups. Genetic distances were large in particular within Pleurosicya and Eviota. Estimated divergence times suggest that coral-associated gobies have diversified in parallel to their preferred host corals. In particular, divergence times of Gobiodon species closely match those estimated for their typical host coral genus Acropora.     

Insights on plant interaction between dominating species from patterns of plant association: expected covariance of pin-point cover measurements of two species

It has been suggested that in order to infer ecological processes from observed patterns of species abundance we need to investigate the covariance in species abundance. Consequently, an expression for the expected covariance of pin-point cover measurements of two species is developed. By comparing the observed covariance with the expected covariance we get a new type of information on the spatial arrangement of two species. Here the discrepancy between the observed and expected covariance may be thought of as a measure of the spatial configuration of the two species that may indicate underling ecological processes. The method is applied in a case study of Calluna vulgaris and Deschampsia flexuosa on dry heathland sites. The observed covariance of Calluna and Deschampsia at the level of the sites was positively and significantly correlated with the expected covariance. Negative covariance was observed on sites where both Calluna and Deschampsia had a high cover, which is in agreement with the notion that both species form distinct patches. Oppositely, at sites where both species have a low cover, we found that both the expected and observed covariance were positive. The proposed measure for the expected covariance of two species does capture information on the combined spatial configuration of the two species if the species are common. We show how this may be relevant for understanding the underlying ecological processes leading to the observed covariance.     

Canopy structure versus physiology effects on net photosynthesis of mountain grasslands differing in land use

The present paper aims at investigating how changes in canopy structure and species physiology associated with the abandonment of mountain meadows and pastures affect their net photosynthesis. For this purpose, a multi-layer vegetation–atmosphere transfer (VAT) model is employed, which explicitly takes into account the structural and functional properties of the various canopy components and species. Three sites differing in land use are investigated, a meadow, a pasture and an abandoned area. Model simulations agree reasonably with measured canopy net photosynthetic rates, the meadow featuring the highest daily net photosynthesis, followed by the pasture and, finally, the abandoned area. A detailed process analysis suggests this ranking to be mainly due to bulk canopy physiology, which decreases from the meadow to the pasture and the abandoned area, reflecting species composition and species-specific photosynthetic capacities. Differences between the canopies with regard to canopy structure are found to be of minor importance. The amounts of green, photosynthetically active plant matter are too similar at the three sites to be a major source of variation in net photosynthesis. Large differences exist between the canopies with regard to the amount of photosynthetically inactive phytoelements. Even though a model analysis showed them to be potentially important, most of them are accumulated close to the ground surface, where they exert little influence on canopy net photosynthesis.     

Refueling while flying: foraging bats combust food rapidly and directly to power flight

Flying vertebrates, such as bats, face exceptionally high energy costs during active flapping flight. Once airborne, energy turnover may exceed basal metabolic rate by a factor of up to 15. Here, we asked whether fuel that powers flight originates from exogenous (dietary nutrients), endogenous sources (mostly body lipids or glycogen), or a combination of both. Since most insectivorous bats fly continuously over relatively long time periods during foraging, we assumed that slowly mobilized glycogen, although suitable for supporting brief sallying flights, is inadequate to power aerial insect-hunting of bats. We hypothesized that the insect-feeding Noctilio albiventris rapidly mobilizes and combusts nutrients from insects it has just eaten instead of utilizing endogenous lipids. We used the stable carbon isotope ratio in the bats' exhaled breath (delta13C(brth)) to assess the origin of metabolized substrates of resting and flying N. albiventris in two nutritional conditions: fasted and recently fed. The breath of fasted resting bats was depleted in 13C in relation to their insect diet (delta13C(diet)), indicating the combustion of 13C depleted body lipids. In contrast to this, delta13C(brth) of bats that had recently fed closely matched delta13C(diet) in both resting and flying bats, suggesting a quick mobilization of ingested nutrients for metabolism. In contrast to most non-volant mammals, bats have evolved the ability to fuel their high energy expenditure rates through the rapid combustion of exogenous nutrients, enabling them to conquer the nocturnal niche of aerial insectivory.     

Evaluation of ecological network analysis: Validation of output

Ecological network analysis (ENA) is a modeling approach increasingly being used to evaluate food webs and provide an ecosystem-based approach to resource management. Unfortunately, validation of ENA output is rarely performed. This study represents part of a larger effort to critically evaluate ENA. Here we validate ENA output using stable isotope analysis (SIA), and where validation is not met, determine the effects of modifying trophic networks to reflect validation.