Little effect of forest age on oribatid mites on the bark of trees

This study investigates the effect of forest age (20-, 50-, 160-year-old, and primeval forest) on oribatid mite communities on the bark of oak trees in the National Park Pusza Białowieża in eastern Poland. We hypothesized that oribatid mite diversity on bark peaks at forests of intermediate age and that the number of parthenogenetic species of oribatid mites is highest in young stands. In contrast to these hypotheses, the diversity, density, number of juveniles, community structure and the mode of reproduction of oribatid mite species were not significantly affected by forest age. None of the oribatid mite species occurred exclusively on trees of a specific age. The results suggest that oribatid mite communities on the bark of trees are minimally affected by tree harvesting regimes. In contrast to oribatid mites in soil, communities on bark appear to be less sensitive to disturbances.     

Impacts from Deposition on Swedish Forest Ecosystems Identified by Integrated Monitoring

Integrated monitoring of ecosystems (IM) is an international co-operative programme (ICP) to control effects of air pollution and climate change on water, soil and biological systems. It is a part of the Convention on Long-Range Transboundary Air Pollution (CLRTAP) of the United Nations Economic Commission of Europe (UN/ECE). The ICP-IM is undertaken on sites/catchments to investigate acidification, eutrophication and heavy metals with an integrated approach. In Sweden, long-term time series from forest ecosystems, with a long and stable continuity, will reveal trends and changes in processes and enable modelling to be undertaken. Investigations of acidity/alkalinity in relation to mineral and organic acids indicated the importance of atmospheric deposition. Recent results show very high inorganic nitrogen retention (99%), a net loss of sulphur originating mainly from organic horizons, and a high inorganic aluminium content in the illuvial soil horizons which could be detrimental to forests. Forest deficiency could also be caused by an observed ongoing translocation of Zn to deeper soil layers implying a movement towards increased release to surface waters.     

The Physcomitrella genome reveals evolutionary insights into the conquest of land by plants

We report the draft genome sequence of the model moss Physcomitrella patens and compare its features with those of flowering plants, from which it is separated by more than 400 million years, and unicellular aquatic algae. This comparison reveals genomic changes concomitant with the evolutionary movement to land, including a general increase in gene family complexity; loss of genes associated with aquatic environments (e.g., flagellar arms); acquisition of genes for tolerating terrestrial stresses (e.g., variation in temperature and water availability); and the development of the auxin and abscisic acid signaling pathways for coordinating multicellular growth and dehydration response. The Physcomitrella genome provides a resource for phylogenetic inferences about gene function and for experimental analysis of plant processes through this plant's unique facility for reverse genetics.     

A well-preserved Archaeopteryx specimen with theropod features

A nearly complete skeleton of Archaeopteryx with excellent bone preservation shows that the osteology of the urvogel is similar to that of nonavian theropod dinosaurs. The new specimen confirms the presence of a hyperextendible second toe as in dromaeosaurs and troodontids. Archaeopteryx had a plesiomorphic tetraradiate palatine bone and no fully reversed first toe. These observations provide further evidence for the theropod ancestry of birds. In addition, the presence of a hyperextendible second toe blurs the distinction of archaeopterygids from basal deinonychosaurs (troodontids and dromaeosaurs) and challenges the monophyly of Aves.     

Structure of PTB bound to RNA: specific binding and implications for splicing regulation

The polypyrimidine tract binding protein (PTB) is a 58-kilodalton RNA binding protein involved in multiple aspects of messenger RNA metabolism, including the repression of alternative exons. We have determined the solution structures of the four RNA binding domains (RBDs) of PTB, each bound to a CUCUCU oligonucleotide. Each RBD binds RNA with a different binding specificity. RBD3 and RBD4 interact, resulting in an antiparallel orientation of their bound RNAs. Thus, PTB will induce RNA looping when bound to two separated pyrimidine tracts within the same RNA. This leads to structural models for how PTB functions as an alternative-splicing repressor.     

Deciphering the reaction dynamics underlying optimal control laser fields

Femtosecond high-resolution pump-probe experiments have been used together with theoretical ab initio quantum calculations and wave packet dynamics simulations to decode an optimal femtosecond pulse that is generated from adaptive learning algorithms. This pulse is designed to maximize the yield of the organometallic ion CpMn(CO)3 while hindering the competing fragmentation. The sequential excitation and ionization of the target ion are accomplished by an optimized field consisting of two dominant subpulses with optimal frequencies and time delays.     

Shocks in ion sputtering sharpen steep surface features

We report a regime of ion beam sputtering that occurs for sufficiently steep slopes. High slopes propagate over large distances without dissipating the steepest features. Both the propagation velocity and the dynamically selected slope are universal, independent of the details of the initial shape of the surface. The resulting behavior can be understood as the propagation of a shock front that self-selects a stable slope, as has been previously observed in thin-film fluid flows. Experiments confirm predictions of the theory. An important implication of the propagative behavior at high surface slopes is that a pattern can be fabricated at a large length scale and, through uniform ion irradiation, reduced to a smaller length scale while preserving, or even sharpening, the sharpest features.     

Mutations in dynein link motor neuron degeneration to defects in retrograde transport

Degenerative disorders of motor neurons include a range of progressive fatal diseases such as amyotrophic lateral sclerosis (ALS), spinal-bulbar muscular atrophy (SBMA), and spinal muscular atrophy (SMA). Although the causative genetic alterations are known for some cases, the molecular basis of many SMA and SBMA-like syndromes and most ALS cases is unknown. Here we show that missense point mutations in the cytoplasmic dynein heavy chain result in progressive motor neuron degeneration in heterozygous mice, and in homozygotes this is accompanied by the formation of Lewy-like inclusion bodies, thus resembling key features of human pathology. These mutations exclusively perturb neuron-specific functions of dynein.