A Synthetic Approach to Reconstruct the Evolutionary and Functional Innovations of the Plant Histone Variant H2A.W

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Estimation of tree biomass of Norway spruce forest in the Plešné Lake catchment,the Bohemian Forest

This paper evaluates the total biomass and pools of major nutrients and ecologically important metals of the tree layer in the catchment of Ple?né jezero (PL) in the Bohemian Forest (?umava, Czech Republic), and compares them to analogous data on understory vegetation and soils. The results are based on field measurements and semi-automatic image analyses of aerial orthophotographs. The tree layer was relatively sparse with open canopy in some parts of the catchment. Stand density varied between 44 and 328 individuals per hectare. The catchment weighted mean total biomass of trees was 134 t ha^?1 dry weight, of which needles, branches, roots, and stems represented 5%, 10%, 14%, and 71%, respectively. The stem wood and bark represented 67% and 4%, respectively, of the total tree biomass. The catchment weighted mean element pools were 568 and 3.0 mol m^?2 (i.e., 68 and 0.42 t ha^?1) for C and N, respectively. The other pools were 76 mmol P m^?2, 602 mmol Ca m^?2, 133 mmol Mg m^?2, 39 mmol Na m^?2, 347 mmol K m^?2, 19 mmol Al m^?2, 6.2 mmol Fe m^?2, and 35 mmol Mn m^?2. The element pools accumulated in the tree biomass represented from < 1% (Al, Fe) to 37% (C) of their total pools (soil + tree layer + understory vegetation) in the catchment. Pools of Ca and Mg in the tree biomass were similar to their exchangeable pools in the catchment soils, while those of K were 3 times higher. Nutrient (N, P, Ca, Mg, and K) and C pools in the tree biomass were 2–11 times higher than those in the understory vegetation, with the minimum for P and maximum for C.     

The halomethylketone derivative L-Glu-gamma-DL-Ala-CH2Cl and N-methyl-D-aspartate as selective antagonists against L-glutamate and kainate excitation respectively on Retzius cells of the leech, Hirudo medicinalis

Intracellular recordings were made from leech Retzius cells. The action of a range of putative antagonists was examined on the excitatory responses to dicarboxylic amino acids which were applied via a diffusion electrode. The halomethylketone derivative, L-Glu-gamma-DL-Ala-CH2Cl was found to block preferentially the L-glutamate response compared to the kainate response. This compound had no effect on the response to carbachol. N-Methyl-D-aspartate was found to block the response to kainate while having no effect on the responses to L-glutamate, ibotenate or carbachol. This compound had no direct action on the cell. N-Methyl-D-aspartic acid also reduced the excitatory responses to methyltetrahydrofolate and 3- carboxymethylpyrrolidine -2,4-dicarboxylic acid ( CMPDA ). gamma-D-Glutamyl-amino methyl-sulphonate ( GAMS ), while partially blocking the action of kainate, had no effect on the response to ibotenate. gamma-D-Glutamylglycine was found to reduce the response to L-glutamate, ibotenate, kainate, quisqualate and CMPDA . CMPDA , a tricarboxylic acid derivative of kainate, was found to be approximately equipotent with kainate on leech Retzius cells. This compound was partially blocked by N-methyl-D-aspartate. The present study demonstrates that it is possible to differentially block L-glutamate and kainate on leech Retzius cells and indicates that they are acting on separate components of the membrane.     

Effect of population size and selection on Toll-like receptor diversity in populations of Galápagos mockingbirds

The interactions of evolutionary forces are difficult to analyse in free-living populations. However, when properly understood, they provide valuable insights into evolutionary biology and conservation genetics. This is particularly important for the interplay of genetic drift and natural selection in immune genes that confer resistance to disease. The Galápagos Islands are inhabited by four closely related species of mockingbirds (Mimus spp.). We used 12 different-sized populations of Galápagos mockingbirds and one population of their continental relative northern mockingbird (Mimus polyglottos) to study the effects of genetic drift on the molecular evolution of immune genes, the Toll-like receptors (TLRs: TLR1B, TLR4 and TLR15). We found that neutral genetic diversity was positively correlated with island size, indicating an important effect of genetic drift. However, for TLR1B and TLR4, there was little correlation between functional (e.g., protein) diversity and island size, and protein structural properties were largely conserved, indicating only a limited effect of genetic drift on molecular phenotype. By contrast, TLR15 was less conserved and even its putative functional polymorphism correlated with island size. The patterns observed for the three genes suggest that genetic drift does not necessarily dominate selection even in relatively small populations, but that the final outcome depends on the degree of selection constraint that is specific for each TLR locus.     

Microtaphonomy of bioclasts and paleoecology of microencrusters from Upper Jurassic spongiolithic limestones (External Prebetic,Southern Spain)

Microencrusters and microtaphonomic features of the Oxfordian spongiolithic limestones of the External Prebetic were studied using thin-section analysis. The spongiolithic limestone is a bioclastic-rich packstone with common echinoderm, mollusc and brachiopod remains. The bioclasts show a high fragmentation index and frequent microborings. The encrustation index (E _i) is higher for fragments of serpulids, ammonoids and bivalves, and increases with the initial grain-size of bioclasts. The main microencrusters consist of benthic microbial communities (BMC) and nubeculariids, as well as subordinate calcareous and siliceous agglutinated foraminifera, serpulids and bryozoans. BMC are usually the first colonizers, and encrusting foraminifera mainly appear on bioclasts larger than 2 mm. BMC dominate in well-developed encrustations on upward facing surfaces of larger bioclasts that are also colonized by foraminifera (nubeculariids and Subdelloidina). Bullopora, serpulids and bryozoans are more common on lower surfaces. The fact that the values of encrustation index, encrustation thickness and diversity of the microencrusters increase with the size of bioclasts is related to a higher stability and exposure time of the available bioclastic substrate. The microencruster distribution on upper and lower surfaces of large bioclasts may be related to photic control, space competition and/or predation avoidance.     

Necroptosis inhibition counteracts neurodegeneration,memory decline,and key hallmarks of aging,promoting brain rejuvenation

Age is the main risk factor for the development of neurodegenerative diseases. In the aged brain, axonal degeneration is an early pathological event, preceding neuronal dysfunction, and cognitive disabilities in humans, primates, rodents, and invertebrates. Necroptosis mediates degeneration of injured axons, but whether necroptosis triggers neurodegeneration and cognitive impairment along aging is unknown. Here, we show that the loss of the necroptotic effector Mlkl was sufficient to delay age-associated axonal degeneration and neuroinflammation, protecting against decreased synaptic transmission and memory decline in aged mice. Moreover, short-term pharmacologic inhibition of necroptosis targeting RIPK3 in aged mice, reverted structural and functional hippocampal impairment, both at the electrophysiological and behavioral level. Finally, a quantitative proteomic analysis revealed that necroptosis inhibition leads to an overall improvement of the aged hippocampal proteome, including a subclass of molecular biofunctions associated with brain rejuvenation, such as long-term potentiation and synaptic plasticity. Our results demonstrate that necroptosis contributes to age-dependent brain degeneration, disturbing hippocampal neuronal connectivity, and cognitive function. Therefore, necroptosis inhibition constitutes a potential geroprotective strategy to treat age-related disabilities associated with memory impairment and cognitive decline.     

Inferring species roles in metacommunity structure from species co-occurrence networks

A long-standing question in community ecology is what determines the identity of species that coexist across local communities or metacommunity assembly. To shed light upon this question, we used a network approach to analyse the drivers of species co-occurrence patterns. In particular, we focus on the potential roles of body size and trophic status as determinants of metacommunity cohesion because of their link to resource use and dispersal ability. Small-sized individuals at low-trophic levels, and with limited dispersal potential, are expected to form highly linked subgroups, whereas large-size individuals at higher trophic positions, and with good dispersal potential, will foster the spatial coupling of subgroups and the cohesion of the whole metacommunity. By using modularity analysis, we identified six modules of species with similar responses to ecological conditions and high co-occurrence across local communities. Most species either co-occur with species from a single module or are connectors of the whole network. Among the latter are carnivorous species of intermediate body size, which by virtue of their high incidence provide connectivity to otherwise isolated communities playing the role of spatial couplers. Our study also demonstrates that the incorporation of network tools to the analysis of metacommunity ecology can help unveil the mechanisms underlying patterns and processes in metacommunity assembly.