Positive selection systems for discovery of novel polyester biosynthesis genes based on fatty acid detoxification.

The photosynthetic bacterium Rhodobacter capsulatus can grow with short- to long-chain fatty acids as the sole carbon source (R. G. Kranz, K. K. Gabbert, T. A. Locke, and M. T. Madigan, Appl. Environ. Microbiol. 63:3003-3009, 1997). Concomitant with growth on fatty acids is the production to high levels of the polyester storage compounds called polyhydroxyalkanoates (PHAs). Here, we describe colony screening and selection systems to analyze the production of PHAs in R. capsulatus. A screen with Nile red dissolved in acetone distinguishes between PHA producers and nonproducers. Unlike the wild type, an R. capsulatus PhaC- strain with the gene encoding PHA synthase deleted is unable to grow on solid media containing high concentrations of certain fatty acids. It is proposed that this deficiency is due to the inability of the PhaC- strain to detoxify the surrounding medium by consumption of fatty acids and their incorporation into PHAs. This fatty acid toxicity phenotype is used in selection for the cloning and characterization of heterologous phaC genes.     

Distribution of amiloride-sensitive sodium channels in the oral cavity of the hamster

The distribution of amiloride-sensitive sodium channels (ASSCs) in taste buds isolated from the oral cavity of hamsters was assessed by patch clamp recording. In contrast to the case for rats, taste cells from the fungiform, foliate and vallate papillae and from the soft palate all contain functional ASSCs. The differential distribution of ASSCs between the hamster and the rat may be important for understanding the physiology underlying the differing behavioral responses of these species to sodium salts.      

Monitoring individual development of isolated wheat zygotes: a novel approach to study early embryogenesis

Summary A culture method has been established by which development of isolated wheat (Triticum aestivum L.) zygotes can be monitored individually until formation of multicellular structures. As was shown recently, these isolated zygotes have a high capacity to form differentiated embryos and normal plants, and thus constitute a suitable object to study early embryogenesis. After being isolated within 6 h after pollination (hap), zygotes were immobilized in an agarose droplet directly on a microscopic chamber slide, which allows for both subsequent development through co-culture with feeder aggregates, as well as detailed observation and photographic documentation of individiual behavior. Shortly after fertilization, the wheat zygote, like the unfertilized egg cell, is characterized by one conspicuous nucleolus. Typically, a second and a third nucleolus appeared between 5 and 8.5 hap. Between 7 and 15 hap, we observed nucleolar vacuolation indicating enhanced ribosomal activity. Continuous cell expansion with slight cell elongation was detected until around 15 hap, followed by a period of transitory reduction in cell volume which roughly corresponded with mitosis. Mitotic prophase of a zygote could easily be detected by the disappearance of all nucleoli within a few minutes. The division plane was generally established perpendicular to the formerly established cell elongation axis. At cytokinesis, which was completed by 19 hap in 90% of the individuals observed, 2 or 3 nucleoli were detected again per daughter cell. The first cell division, including the establishment of a cleavage furrow with intercellular spaces, was completed in all cases within 23 hap. Since this result is in accordance with what is known from earlier studies based upon fixed material, and since the zygotes subsequently continue embryogenesis, in vitro development is assumed to be analogous to that in planta. This experimental system constitutes a valuable experimental tool for further detailed research, both at the cellular and at the molecular level.Abbreviations hap hours after pollination - NOR nucleolus-organizing region     

Multiscale Investigation of Sodium-Ion Battery Anodes: Analytical Techniques and Applications

The anode/electrolyte interface behavior, and by extension, the overall cell performance of sodium-ion batteries is determined by a complex interaction of processes that occur at all components of the electrochemical cell across a wide range of size- and timescales. Single-scale studies may provide incomplete insights, as they cannot capture the full picture of this complex and intertwined behavior. Broad, multiscale studies are essential to elucidate these processes. Within this perspectives article, several analytical and theoretical techniques are introduced, and described how they can be combined to provide a more complete and comprehensive understanding of sodium-ion battery (SIB) performance throughout its lifetime, with a special focus on the interfaces of hard carbon anodes. These methods target various length- and time scales, ranging from micro to nano, from cell level to atomistic structures, and account for a broad spectrum of physical and (electro)chemical characteristics. Specifically, how mass spectrometric, microscopic, spectroscopic, electrochemical, thermodynamic, and physical methods can be employed to obtain the various types of information required to understand battery behavior will be explored. Ways are then discussed how these methods can be coupled together in order to elucidate the multiscale phenomena at the anode interface and develop a holistic understanding of their relationship to overall sodium-ion battery function.     

Genetic diversity and population structure of food-borne Staphylococcus carnosus strains

The species Staphylococcus carnosus is a non-pathogenic representative of the coagulase negative staphylococci. Specific strains are applied as meat starter cultures. The species consists of two subspecies, S. carnosus ssp. carnosus and S. carnosus ssp. utilis. In order to place S. carnosus strains, characterized in former studies, in a genetic background that allows a typing of candidates for starter cultures, a Multilocus Sequence Typing (MLST) scheme was developed. Internal fragments of the genes tpiA, xprT, dat, gmk, glpK, narG, cstA, encoding triosephosphate isomerase, xanthine phosphoribosyltransferase, d-amino acid aminotransferase, guanylate kinase, glycerol kinase, the α-chain of the respiratory nitrate reductase, and a carbon starvation protein where chosen. Genes were selected based on their equal distribution in the genome, taxonomic value in subspecies differentiation and metabolic function. This MLST was applied to 44 S. carnosus strains, most of them previously analyzed for their suitability as starter cultures.The number of alleles varied between zero (tpiA) and five (cstA) and allowed the definition of nine sequence types (ST). ST1 was most abundant (18 strains), followed by ST2 (8) and ST4 (6). The nine STs confirmed a close relationship of all strains despite their isolation source and year, but lacked correlation with physiological activities relevant for starter cultures. The low amount of STs in the strain set lets us suggest that recombination between strains is rare. Thus, it is hypothesized that evolutionary events seem to be due to single point mutations rather than intrachromosomal recombination, and that the species possesses a clonal population structure.     

Quinolines as a novel structural class of potent and selective PDE4 inhibitors. Optimisation for inhaled administration

Crystallography driven optimisation of a lead derived from similarity searching of the GSK compound collection resulted in the discovery of quinoline-3-carboxamides as highly potent and selective inhibitors of phosphodiesterase 4B. This series has been optimized to GSK256066, a potent PDE4B inhibitor which also inhibits LPS induced production of TNF-α from isolated human peripheral blood mononuclear cells with a pIC₅₀ of 11.1. GSK256066 also has a suitable profile for inhaled dosing.     

Patterns and mechanisms of invasive plant impacts on North American birds: a systematic review

Understanding how invasive plants affect biodiversity is a crucial conservation need. Numerous studies examine impacts of invasions on birds, but trends in these effects have not been synthesized. We reviewed 128 studies from North America to quantify the frequency of positive, negative, and neutral (non-significant) effects of invasive plants on avian ecology, and then evaluated support for proposed mechanisms of impacts. Our frequency-based approach enabled us to draw value from the full breadth of available literature, including articles that do not provide information necessary for meta-analyses and articles examining understudied phenomena. Total avian abundance and prevalence of individual bird species were usually unaffected by invasion, with 48.9 and 57.2% of tests showing neutral results, respectively. Avian richness decreased with invasion in 41.3% of tests. Although birds often preferred nesting in invasive vegetation (45.0% of tests), effects on nest survival were typically neutral (57.9%). Multiple metrics (e.g. body condition, fledgling survival) have received scant attention. Some of the patterns we highlight differ across ecological contexts, emphasizing the need to understand impact mechanisms. Several studies have directly linked invasion impacts to altered nest-site availability, habitat heterogeneity, and food supplies. There is mixed evidence that plant architecture impacts nest-site selection and nest predation. Our review highlights the nonuniform consequences of biological invasions. The high frequency of reported neutral effects suggests that invasions often have minimal impacts on birds, but positive and negative impacts certainly can arise. Managers considering eradicating invasive plants for avian conservation should monitor impacts locally to determine whether eradication will be beneficial.     

Identification of a Common Non-Apoptotic Cell Death Mechanism in Hereditary Retinal Degeneration

Cell death in neurodegenerative diseases is often thought to be governed by apoptosis; however, an increasing body of evidence suggests the involvement of alternative cell death mechanisms in neuronal degeneration. We studied retinal neurodegeneration using 10 different animal models, covering all major groups of hereditary human blindness (rd1, rd2, rd10, Cngb1 KO, Rho KO, S334ter, P23H, Cnga3 KO, cpfl1, Rpe65 KO), by investigating metabolic processes relevant for different forms of cell death. We show that apoptosis plays only a minor role in the inherited forms of retinal neurodegeneration studied, where instead, a non-apoptotic degenerative mechanism common to all mutants is of major importance. Hallmark features of this pathway are activation of histone deacetylase, poly-ADP-ribose-polymerase, and calpain, as well as accumulation of cyclic guanosine monophosphate and poly-ADP-ribose. Our work thus demonstrates the prevalence of alternative cell death mechanisms in inherited retinal degeneration and provides a rational basis for the design of mutation-independent treatments.