Drought’s impact on Ca,Fe, Mg,Mo and S concentration and accumulation patterns in the plants and soil of a Mediterranean evergreen <Emphasis Type="Italic">Quercus </Emphasis><Emphasis Type="Italic">ilex</Emphasis> forest

We conducted a 6-year field manipulation drought experiment in an evergreen Quercus ilex forest where we simulated the drought predicted by GCM and ecophysiological models for the coming decades (an average of 15% soil moisture reduction). We thereby tested the hypothesis that enhanced drought will change Ca, Fe, Mg, Mo and S availability, concentrations and accumulation patterns in Mediterranean ecosystems. The strongest effects of drought occurred in the soil. Drought increased the total soil concentrations of S, the soil extract concentrations of Fe, Mg and S, the Mg saturation in the soil exchangeable complex and tended to increase the percentage base saturation of the soil exchangeable complex. These increased soil concentrations were related to a decrease of plant uptake capacity and not to an increase of soil enzyme activity, which in fact decreased under drier conditions. Drought increased leaf Mg concentrations in the three dominant species although only significantly in Quercus ilex and Arbutus unedo (20 and 14%, respectively). In contrast, drought tended to decrease Ca in Phillyrea latifolia (18%) and Ca and Fe concentrations in the wood of all three species. Drought increased Ca and Fe concentrations in the roots of Quercus ilex (26 and 127%). There was a slight general trend to decrease total biomass accumulation of nutrients that depend on water flux such as Mg, Fe and S. This effect was related to a decrease of soil moisture that reduced soil flow, and to a decrease in photosynthetic capacity, sap flow, transpiration and growth, and therefore plant uptake capacity under drought observed in Quercus ilex and Arbutus unedo. On the contrary, drought increased Mo accumulation in aboveground biomass in Phillyrea latifolia and reduced Mo accumulation in Arbutus unedo by reducing growth and wood Mo concentrations (51%). Phillyrea latifolia showed a great capacity to adapt to drier conditions, with no decrease in growth, an increase of Mo uptake capacity and a decrease in leaf Ca concentration, which was related to a decrease in transpiration under drought. The results indicate asymmetrical changes in species capacity to accumulate these elements, which are likely to produce changes in inter-specific competitive relations among dominant plant species and in their nutritional quality as food sources. The results also indicate that drought tended to decrease nutrient content in aboveground biomass, mainly through the decrease in growth and transpiration of the most sensitive species and caused an increase in the availability of these nutrients in soil. Thus, drought decreased the ecosystem’s capacity to retain Mg, Fe and S, facilitating their loss in torrential rainfalls.     

Zero erucic acid trait of rapeseed (<Emphasis Type="Italic">Brassica napus</Emphasis> L.) results from a deletion of four base pairs in the <Emphasis Type="Italic">fatty acid elongase 1</Emphasis> gene

The fatty acid elongase 1 (FAE1) gene is a key gene in the erucic acid biosynthesis in rapeseed. The complete coding sequences of the FAE1 gene were isolated separately from eight high and zero erucic acid rapeseed cultivars (Brassica napus L.). A four base pair deletion between T1366 and G1369 in the FAE1 gene was found in a number of the cultivars, which leads to a frameshift mutation and a premature stop of the translation after the 466th amino acid residue. This deletion was predominantly found in the C-genome and rarely in the A-genome of B. napus. Expression of the gene isoforms with the four base pair deletion in a yeast system generated truncated proteins with no enzymatic activity and could not produce very long chain fatty acids as the control with an intact FAE1 gene did in yeast cells. In the developing rape seeds the FAE1 gene isoforms with the four base pair deletion were transcribed normally but failed to translate proteins to form a functional complex. The four base pair deletion proved to be a mutation responsible for the low erucic acid trait in rapeseed and independent from the point mutation reported by Han et al. (Plant Mol Biol 46:229–239, 2001). Gang Wu, Yuhua Wu contribute equally to this article.     

Characterization of Protein–Protein Interfaces

We analyze the characteristics of protein–protein interfaces using the largest datasets available from the Protein Data Bank (PDB). We start with a comparison of interfaces with protein cores and non-interface surfaces. The results show that interfaces differ from protein cores and non-interface surfaces in residue composition, sequence entropy, and secondary structure. Since interfaces, protein cores, and non-interface surfaces have different solvent accessibilities, it is important to investigate whether the observed differences are due to the differences in solvent accessibility or differences in functionality. We separate out the effect of solvent accessibility by comparing interfaces with a set of residues having the same solvent accessibility as the interfaces. This strategy reveals residue distribution propensities that are not observable by comparing interfaces with protein cores and non-interface surfaces. Our conclusions are that there are larger numbers of hydrophobic residues, particularly aromatic residues, in interfaces, and the interactions apparently favored in interfaces include the opposite charge pairs and hydrophobic pairs. Surprisingly, Pro-Trp pairs are over represented in interfaces, presumably because of favorable geometries. The analysis is repeated using three datasets having different constraints on sequence similarity and structure quality. Consistent results are obtained across these datasets. We have also investigated separately the characteristics of heteromeric interfaces and homomeric interfaces.     

The decomposition of α-aminophosphine oxides to phosphonic acid derivatives (P<Superscript>III</Superscript>)

Aminophosphine oxides and aminophosphonates are, in general, very stable compounds. However, following phosphorus–carbon bond cleavage in aqueous acidic media these compounds sometimes decompose to phosphonic acids derivatives (P^III). Despite some controversy in the literature, careful analysis supported by theoretical studies leads to the conclusion that decomposition to P^III derivatives proceeds via an elimination reaction. Figure The decomposition of α-aminophosphine oxides to phosphonic acid derivatives (P^III)     

5a-Carba-β-D-glucopyranose derivatives as novel sodium-dependent glucose cotransporter 2 (SGLT2) inhibitors for the treatment of type 2 diabetes

5a-Carba-β-D-glucopyranose derivatives were synthesized and identified as novel SGLT2-selective inhibitors. These inhibitors exhibited potent SGLT2 inhibition with high selectivity over SGLT1. Among the tested compounds, 6f indicated the most potent hSGLT2 inhibition and the highest selectivity over hSGLT1. Moreover, the pharmacokinetics data also showed that 6h, which had the same aglycon structure as sergliflozin-active (3-active), had a threefold longer half-life time (T(1/2)) than sergliflozin (3) with a high distribution volume in db/db mice. Subsequently, 6h lowered blood glucose levels as much as 3 and showed longer hypoglycemic action than 3 in db/db mice.     

Modified cell cycle status in a mouse model of altered neuronal vulnerability (slow Wallerian degeneration; <Emphasis Type="Italic">Wld</Emphasis><Superscript><Emphasis Type="Italic">s</Emphasis></Superscript>)

Background  

Altered neuronal vulnerability underlies many diseases of the human nervous system, resulting in degeneration and loss of neurons. The neuroprotective slow Wallerian degeneration (Wld ^s ) mutation delays degeneration in axonal and synaptic compartments of neurons following a wide range of traumatic and disease-inducing stimuli, providing a powerful experimental tool with which to investigate modulation of neuronal vulnerability. Although the mechanisms through which Wld ^s confers neuroprotection remain unclear, a diverse range of downstream modifications, incorporating several genes/pathways, have been implicated. These include the following: elevated nicotinamide adenine dinucleotide (NAD) levels associated with nicotinamide mononucleotide adenylyltransferase 1 (Nmnat1; a part of the chimeric Wld ^s gene); altered mRNA expression levels of genes such as pituitary tumor transforming gene 1 (Pttg1); changes in the location/activity of the ubiquitin-proteasome machinery via binding to valosin-containing protein (VCP/p97); and modified synaptic expression of proteins such as ubiquitin-activating enzyme E1 (Ube1).     

LTR retrotransposons and the evolution of dosage compensation in <Emphasis Type="Italic">Drosophila</Emphasis>

Background  

Dosage compensation in Drosophila is the epigenetic process by which the expression of genes located on the single X-chromosome of males is elevated to equal the expression of X-linked genes in females where there are two copies of the X-chromosome. While epigenetic mechanisms are hypothesized to have evolved originally to silence transposable elements, a connection between transposable elements and the evolution of dosage compensation has yet to be demonstrated.     

Risk assessment strategies for transgenic plants

Advances in recombinant DNA technology have created advantages for the development of plants with high agro-economical values. Since the production of transgenic plants, some issues concerning the safe use of these plants and their products have been under debate throughout the world. In this respect, the potential risks and benefits of transgenic plants need to be evaluated objectively. Risk assessment of transgenic crops is a basic prerequisite for monitoring the possible risks that could arise upon the release and use of transgenic plants. To get a meaningful tool for decision making, risk assessment needs to be carried out in a scientific sound and transparent manner. There are specific governmental regulations in many countries for the safety assessment of genetically modified (GM) crops. Furthermore, there are some international agreements, which regulate the cultivation and commercialization of transgenic plants and their derivatives. Internationally accepted risk assessment strategies have been performed to evaluate the safe use of a large variety of GM crops. The main objectives of these regulations and risk assessment strategies are focused to protect human/animal health and the environment.     

Current knowledge of microbial community structures in landfills and its cover soils

Landfills are a vital component of our waste handling processes. Our lack of knowledge on the microbial processes in these systems, however, hampers our ability to design the next generation of landfills that: (1) enhance the rate and extent of waste decomposition, (2) produce byproducts of some value (e.g., methane that can be used for energy generation), and, (3) minimize their overall impact on driving climate change through the emission of greenhouse gases. In this review, the current state of knowledge the microbial community structure and activity in both the refuse and overlying cover soils is discussed, and suggestions provided for future research in this critical aspect of our infrastructure.     

Genetic diversity,genetic drift and mixed mating system in small subpopulations of <Emphasis Type="Italic">Dyckia ibiramensis</Emphasis>, a rare endemic bromeliad from Southern Brazil

Dyckia ibiramensis is a naturally rare, endemic and threatened bromeliad which occurs naturally on 4 km of rocky river outcroppings in Southern Brazil. For this study, subpopulations of the species were characterized based on size and genetics, to compile information for in situ and ex situ conservation strategies. A census of the rosettes was undertaken for each subpopulation and seven allozyme polymorphic loci were used to estimate genetic diversity and structure of adults and offspring and assess the mating system. In general, the subpopulations were small and most of the rosettes were aggregated into clumps. The species showed a high genetic diversity ([^(H)]_e = 0.219 \hat{H}_{e} = 0.219 ) and significant fixation index ([^(f)] = 0.642, \hat{f} = 0.642, P ≤ 0.05). The estimate of differentiation among all adult subpopulations indicate pronounced genetic structure ([^(G)]^￠_ST = 0.674 \hat{G}^{\prime}_{ST} = 0.674 ). D. ibiramensis has a mixed mating system and multilocus outcrossing rates [^(t)]_m \hat{t}_{m} were variable between subpopulations. This study demonstrates the importance of in situ preservation of all subpopulations for the maintenance of species diversity. For effective ex situ conservation, it would be necessary to collect seeds from 52 to 99 seed-rosettes, depending on the target population.