Built to last: The structure,function, and evolution of primate dental enamel

The teeth of every primate, living and extinct, are covered by a hard, durable layer of enamel. This is not unique: Almost all mammals have enamel-covered teeth. In addition, all of the variations in enamel structure that occur in primates are also found in other groups of mammals. Nevertheless, the very complexity of enamel and the variation we see in it on the teeth of living and fossil primates raise questions about its evolutionary significance. Is the complex structure of primate enamel adaptive? What, if anything, does enamel structure tell us about primate phylogeny? To answer these questions, we need to look more closely at the characteristics of prismatic enamel in primates and at the distribution of those characteristics, both in relation to our knowledge of primate dental function and feeding ecology and from a phylogenetic perspective.     

Automatic extraction and measurement of individual trees from mobile laser scanning point clouds of forests

Background and AimsIn addition to terrestrial laser scanning (TLS), mobile laser scanning (MLS) is increasingly arousing interest as a technique which provides valuable 3-D data for various applications in forest research. Using mobile platforms, the 3-D recording of large forest areas is carried out within a short space of time. Vegetation structure is described by millions of 3-D points which show an accuracy in the millimetre range and offer a powerful basis for automated vegetation modelling. The successful extraction of single trees from the point cloud is essential for further evaluations and modelling at the individual-tree level, such as volume determination, quantitative structure modelling or local neighbourhood analyses. However, high-precision automated tree segmentation is challenging, and has so far mostly been performed using elaborate interactive segmentation methods.MethodsHere, we present a novel segmentation algorithm to automatically segment trees in MLS point clouds, applying distance adaptivity as a function of trajectory. In addition, tree parameters are determined simultaneously. In our validation study, we used a total of 825 trees from ten sample plots to compare the data of trees segmented from MLS data with manual inventory parameters and parameters derived from semi-automatic TLS segmentation.Key ResultsThe tree detection rate reached 96 % on average for trees with distances up to 45 m from the trajectory. Trees were almost completely segmented up to a distance of about 30 m from the MLS trajectory. The accuracy of tree parameters was similar for MLS-segmented and TLS-segmented trees.ConclusionsBesides plot characteristics, the detection rate of trees in MLS data strongly depends on the distance to the travelled track. The algorithm presented here facilitates the acquisition of important tree parameters from MLS data, as an area-wide automated derivation can be accomplished in a very short time.     

NO removal in continuous BioDeNOx reactors: Fe(II)EDTA2- regeneration, biomass growth, and EDTA degradation

BioDeNOx is a novel technique for NOx removal from industrial flue gases. In principle, BioDeNOx is based on NO absorption into an aqueous Fe(II)EDTA2- solution combined with biological regeneration of that scrubber liquor in a bioreactor. The technical and economical feasibility of the BioDeNOx concept is strongly determined by high rate biological regeneration of the aqueous Fe(II)EDTA2- scrubber liquor and by EDTA degradation. This investigation deals with the Fe(II)EDTA2- regeneration capacity and EDTA degradation in a lab-scale BioDeNOx reactor (10-20 mM Fe(II)EDTA2-, pH 7.2 +/- 0.2, 55 degrees C), treating an artificial flue gas (1.5 m3/h) containing 60-155 ppm NO and 3.5-3.9% O2. The results obtained show a contradiction between the optimal redox state of the aqueous FeEDTA solution for NO absorption and the biological regeneration. A low redox potential (below -150 mV vs. Ag/AgCl) is needed to obtain a maximal NO removal efficiency from the gas phase via Fe(II)EDTA2- absorption. Fe(III)EDTA- reduction was found to be too slow to keep all FeEDTA in the reduced state. Stimulation of Fe(III)EDTA- reduction via periodical sulfide additions (2 mM spikes twice a week for the conditions applied in this study) was found to be necessary to regenerate the Fe(II)EDTA2- scrubber liquor and to achieve stable operation at redox potentials below -150 mV (pH 7.2 +/- 0.2). However, redox potentials of below -200 mV should be avoided since sulfide accumulation is unwanted because it is toxic for NO reduction. Very low values for biomass growth rate and yield, respectively, 0.043/d and 0.009 mg protein per mg ethanol, were observed. This might be due to substrate limitations, that is the electron acceptors NO and presumably polysulfide, or to physiological stress conditions induced by the EDTA rich medium or by radicals formed in the scrubber upon the oxidation of Fe(II)EDTA2- by oxygen present in the flue gas. Radicals possibly also induce EDTA degradation, which occurs at a substantial rate: 2.1 (+/-0.1) mM/d under the conditions investigated.     

Arachidonic acid metabolism of the murine eosinophil. II. Involvement of the lipoxygenase pathway in the response to the lymphokine eosinophil stimulation promoter

Eosinophil stimulation promoter (ESP) is a murine lymphokine that enhances the migration of eosinophils. Exogenous arachidonic acid between 0.5 and 2 micrograms/ml potentiated the activity of ESP on murine eosinophil migration, whereas such concentrations did not affect migration in the absence of ESP. Among the lipoxygenase products identified from an enriched population of murine eosinophils, leukotriene B4 (optimal activity at 100 ng/ml) and 12-HETE (optimal activity at 2 micrograms/ml) stimulated migration of these cells. Another lipoxygenase product from these cells 15-HETE inhibited ESP-induced migration; between 5 and 10 micrograms/ml 15-HETE decreased by one-half both stimulated migration and 12-HETE biosynthesis. Structurally diverse drugs at concentrations that inhibited HETE biosynthesis inhibited ESP-induced migration. The concentrations that decreased migration activity by one-half were 5 microM NDGA, 10 microM ETYA, and 150 microM BW755C. Aspirin and indomethacin at concentrations reported to inhibit prostaglandin biosynthesis did not substantially inhibit ESP activity, but concentrations of indomethacin above 20 microM caused concentration-dependent inhibition of migration. The selective lipoxygenases inhibitor 134,7,10,13-eicosatetraynoic acid was more potent than ETYA in inhibition of ESP-induced migration, and the selective cyclooxygenase inhibitor 6,9,12-octadecatriynoic acid did not effect inhibition. These results are consistent with the hypothesis that stimulation of eosinophils by the lymphokine ESP involves the generation of lipoxygenase products from arachidonic acid, which positively and negatively regulate the migratory activities of these cells.     

Purification of the flavoproteins 6-hydroxy-D- and 6-hydroxy-L-nicotine oxidase using hydrophobic affinity chromatography

A systematic study of the homologous series of omega-aminoalkyl-agaroses revealed differences in the affinities of 6-hydroxy-D- and 6-hydroxy-L-nicotine oxidase. In contrast to supports with nonpolar alkyl chains, omega-aminoalkyl-agarose showed high affinity towards the L-specific enzyme, while the D-specific oxidase was bound most firmly by omega-aminododecyl-agarose. 6-Hydroxy-L-nicotine oxidase could be desorbed by 1.3M NaCl only in the presence of the substrate L-6-hydroxynicotine. Using the omega-aminoalkyl-agarose, a complete separation of the enantiozymes was accomplished and an efficient purification procedure for both oxidases established.     

Salt-induced Inhibition of Phosphate Transport and Release of Membrane Proteins from Barley Roots

Osmotic shock with sequential 30-minute treatments in ice-cold saline solutions and H₂O released proteins from excised barley roots and inhibited the subsequent uptake of orthophosphate (Pi). The amount of protein released increased sharply at NaCl concentrations above 0.05 molar, approximately the threshold concentration above which Pi uptake was increasingly suppressed. About 60% of the nearly 100 micrograms of protein per gram fresh weight of roots that was eluted in 0.16 molar NaCl treatments apparently had no function in Pi transport, since it was eluted at NaCl concentrations (≤0.05 molar) that did not affect Pi uptake. Although 0.16 molar NaCl completely inhibited Pi uptake, active uptake resumed at about 60% of control rates within 1 to 2 hours. The presence of either puromycin or cycloheximide greatly reduced the recovery of Pi uptake activity after the NaCl treatment. Mannitol and various monovalent and divalent salts at concentrations isosmotic with NaCl also inhibited Pi uptake, but CaCl₂ was consistently the least inhibitory. The correlation between the concentration of the osmotic treatments and the simultaneous loss of protein and Pi uptake activity, together with the evidence that uptake recovery requires protein synthesis, support the hypothesis that the proteins eluted are required for active Pi transport.