Aspects of Nutrition and the Metabolism of Copper in Isopods

Terrestrial immigrants from the sea have to cope with two importantnutritional problems: a shift in pathways of absorption, andthe altered availability of nutrients. The more terrestrialspecies of littoral crustaceans switch to food as the main sourceof water and salts. No serious difficulties accompany the oraluptake of mobile ions, but the vegetarians amongst the immigrantsare required to assume a new attitude with regard to the assimilationor heavier metals. Some important heavy elements, notably Cuand Zn, are soluble in sea water but form rather intractableorganic complexes in plant tissues. Herbivorous amphipods andisopods on land are incapable of extracting copper directlyfrom their primary food sources. To compensate for this shortcoming,help is enlisted from microorganisms, which render the copperpresent in ill-digested fecal material available to the crustaceans.Moreover, in terrestrial and intertidal herbivorous crustaceans—ascompared with their marine relatives—the storage capacityof the hepatopancreas, as well as the efficiency of Cu-assimilation,is augmented; compartmentalization of Cu-storage is more rigorouslycarried through; the movements of Cu and Zn within the bodyare more strictly regulated, copper, for example, being exchangedbetween different compartments in the course of endogenouslyor exogenously induced phases of the animal's life cycle.     

Unravelling the genetic complexity of sorghum seedling development under low‐temperature conditions

Sorghum is a promising alternative to maize for bioenergy production in Europe; however, its use is currently limited by poor adaptation to low temperatures during and after germination. We collected multi‐trait phenotype data under optimal and suboptimal temperatures in a genetically diverse recombinant inbred line (RIL) mapping population showing contrasting segregation patterns for pre‐ and post‐emergence chilling tolerance. Germination, emergence, seedling development, root architecture and seedling survival were assessed in two different seedlots. Emergence and root establishment were found to be the key determinants of development and survival under chilling stress. Highly interactive epistatic quantitative trait loci (QTL) hotspots, including a previously unknown QTL on Sb06 with a significant effect on prolonged chilling survival, were found to regulate different physiological mechanisms contributing to maintenance of growth and development despite the chilling temperatures. The major QTL regions harbour promising candidate genes with known roles in abiotic stress tolerance. Identification of loci in the QTL hotspot regions conferring maintenance of cell division and growth under early chilling stress represents a promising step towards breeding for successful establishment of sorghum in temperate climates.     

On a New Microcerberus from the Red Sea and the Relationship of the Microcerberidea to the Anthuridea (Crustacea, Isopoda)

Microcerberus tabai sp.n. from the Gulf of Elat is described in detail. The relationship of the Microcerberida to the Anthuridea is discussed: the Microcerberidea have none of the synapomorphies of the Anthuridea.     

Quantifying photosynthetic capacity and its relationship to leaf nitrogen content for global-scale terrestrial biosphere models

Photosynthetic capacity and its relationship to leaf nitrogen content are two of the most sensitive parameters of terrestrial biosphere models (TBM) whose representation in global‐scale simulations has been severely hampered by a lack of systematic analyses using a sufficiently broad database. Here, we use data of qualitative traits, climate and soil to subdivide the terrestrial vegetation into functional types (PFT), and then assimilate observations of carboxylation capacity, V_max (723 data points), and maximum photosynthesis rates, A_max (776 data points), into the C₃ photosynthesis model proposed by Farquhar et al. to constrain the relationship of (V_max normalised to 25 °C) to leaf nitrogen content per unit leaf area for each PFT. In a second step, the resulting functions are used to predict per PFT from easily measurable values of leaf nitrogen content in natural vegetation (1966 data points). Mean values of thus obtained are implemented into a TBM (BETHY within the coupled climate–vegetation model ECHAM5/JSBACH) and modelled gross primary production (GPP) is compared with independent observations on stand scale. Apart from providing parameter ranges per PFT constrained from much more comprehensive data, the results of this analysis enable several major improvements on previous parameterisations. (1) The range of mean between PFTs is dominated by differences of photosynthetic nitrogen use efficiency (NUE, defined as divided by leaf nitrogen content), while within each PFT, the scatter of values is dominated by the high variability of leaf nitrogen content. (2) We find a systematic depression of NUE on certain tropical soils that are known to be deficient in phosphorous. (3) of tropical trees derived by this study is substantially lower than earlier estimates currently used in TBMs, with an obvious effect on modelled GPP and surface temperature. (4) The root‐mean‐squared difference between modelled and observed GPP is substantially reduced.     

Does the disturbance hypothesis explain the biomass increase in basin‐wide Amazon forest plot data?

Positive aboveground biomass trends have been reported from old-growth forests across the Amazon basin and hypothesized to reflect a large-scale response to exterior forcing. The result could, however, be an artefact due to a sampling bias induced by the nature of forest growth dynamics. Here, we characterize statistically the disturbance process in Amazon old-growth forests as recorded in 135 forest plots of the RAINFOR network up to 2006, and other independent research programmes, and explore the consequences of sampling artefacts using a data-based stochastic simulator. Over the observed range of annual aboveground biomass losses, standard statistical tests show that the distribution of biomass losses through mortality follow an exponential or near-identical Weibull probability distribution and not a power law as assumed by others. The simulator was parameterized using both an exponential disturbance probability distribution as well as a mixed exponential–power law distribution to account for potential large-scale blowdown events. In both cases, sampling biases turn out to be too small to explain the gains detected by the extended RAINFOR plot network. This result lends further support to the notion that currently observed biomass gains for intact forests across the Amazon are actually occurring over large scales at the current time, presumably as a response to climate change.