Interspecific patterns for egg and clutch sizes of African Bufonidae (Amphibia: Anura)

Little is known about reproductive trade-offs in African amphibians, but such data, particularly in the form of quantitative measurements, are a key for investigating life history evolution. Here we compile and analyze known data on African bufonids from published material and new data from preserved museum specimens, to investigate interspecific patterns of egg and clutch sizes variation. Our data is a composite of mixed sources, including ova data from dissected females and laid clutches from observations in the field. Our study shows that, as body size increases, clutch size increases but egg size decreases, and when correcting for body size, egg size is inversely correlated with clutch size. These parameter interactions however, are different for different reproductive modes. In free-swimming larval developing species, the same trends are recovered, but for lecithotrophic viviparous species no significant correlations could be recovered for clutch size and body size nor for the trade-off between clutch size and egg size, and egg size is positively related to body size. The egg size of Nimbaphrynoides occidentalis (Angel, 1943) is a clear outlier, which may be due to its matrotrophic viviparous reproduction. In addition, we observed no statistical difference between ova data collected from dissections and laid clutch data from field observations, which suggests that such a mixed dataset has utility in comparative analyses.     

Improved protein identification through the use of unstained gels

In this work, a method for improved protein identification of low-abundance proteins using unstained gels, in combination with robotics and matrix-assisted laser desorption/ionization tandem mass spectrometry, has been developed and evaluated. Omitting the silver-staining process resulted in increased protein identification scores, an increase in the number of peptides observed in the MALDI mass spectrum, and improved quality of the tandem mass spectrometry data.     

Burn‐in Free Nonfullerene‐Based Organic Solar Cells

Organic solar cells that are free of burn‐in, the commonly observed rapid performance loss under light, are presented. The solar cells are based on poly(3‐hexylthiophene) (P3HT) with varying molecular weights and a nonfullerene acceptor (rhodanine‐benzothiadiazole‐coupled indacenodithiophene, IDTBR) and are fabricated in air. P3HT:IDTBR solar cells light‐soaked over the course of 2000 h lose about 5% of power conversion efficiency (PCE), in stark contrast to [6,6]‐Phenyl C61 butyric acid methyl ester (PCBM)‐based solar cells whose PCE shows a burn‐in that extends over several hundreds of hours and levels off at a loss of ≈34%. Replacing PCBM with IDTBR prevents short‐circuit current losses due to fullerene dimerization and inhibits disorder‐induced open‐circuit voltage losses, indicating a very robust device operation that is insensitive to defect states. Small losses in fill factor over time are proposed to originate from polymer or interface defects. Finally, the combination of enhanced efficiency and stability in P3HT:IDTBR increases the lifetime energy yield by more than a factor of 10 when compared with the same type of devices using a fullerene‐based acceptor instead.     

Monoacylglycerol Lipases Act as Evolutionarily Conserved Regulators of Non-oxidative Ethanol Metabolism

Fatty acid ethyl esters (FAEEs) are non-oxidative metabolites of ethanol that accumulate in human tissues upon ethanol intake. Although FAEEs are considered as toxic metabolites causing cellular dysfunction and tissue damage, the enzymology of FAEE metabolism remains poorly understood. In this study, we used a biochemical screen in Saccharomyces cerevisiae to identify and characterize putative hydrolases involved in FAEE catabolism. We found that Yju3p, the functional orthologue of mammalian monoacylglycerol lipase (MGL), contributes >90% of cellular FAEE hydrolase activity, and its loss leads to the accumulation of FAEE. Heterologous expression of mammalian MGL in yju3Δ mutants restored cellular FAEE hydrolase activity and FAEE catabolism. Moreover, overexpression or pharmacological inhibition of MGL in mouse AML-12 hepatocytes decreased or increased FAEE levels, respectively. FAEEs were transiently incorporated into lipid droplets (LDs) and both Yju3p and MGL co-localized with these organelles. We conclude that the storage of FAEE in inert LDs and their mobilization by LD-resident FAEE hydrolases facilitate a controlled metabolism of these potentially toxic lipid metabolites.     

Superresolution imaging of biological nanostructures by spectral precision distance microscopy

For the improved understanding of biological systems on the nanoscale, it is necessary to enhance the resolution of light microscopy in the visible wavelength range beyond the limits of conventional epifluorescence microscopy (optical resolution of about 200 nm laterally, 600 nm axially). Recently, various far-field methods have been developed allowing a substantial increase of resolution ("superresolution microscopy", or "lightoptical nanoscopy"). This opens an avenue to 'nano-image' intact and even living cells, as well as other biostructures like viruses, down to the molecular detail. Thus, it is possible to combine light optical spatial nanoscale information with ultrastructure analyses and the molecular interaction information provided by molecular cell biology. In this review, we describe the principles of spectrally assigned localization microscopy (SALM) of biological nanostructures, focusing on a special SALM approach, spectral precision distance/position determination microscopy (SPDM) with physically modified fluorochromes (SPDM(Phymod) . Generally, this SPDM method is based on high-precision localization of fluorescent molecules, which can be discriminated using reversibly bleached states of the fluorophores for their optical isolation. A variety of application examples is presented, ranging from superresolution microscopy of membrane and cytoplasmic protein distribution to dual-color SPDM of nuclear proteins. At present, we can achieve an optical resolution of cellular structures down to the 20-nm range, with best values around 5 nm (～1/100 of the exciting wavelength).     

Importance of rare taxa for bacterial diversity in the rhizosphere of Bt- and conventional maize varieties

Ribosomal 16S rRNA gene pyrosequencing was used to explore whether the genetically modified (GM) Bt-maize hybrid MON 89034 × MON 88017, expressing three insecticidal recombinant Cry proteins of Bacillus thuringiensis, would alter the rhizosphere bacterial community. Fine roots of field cultivated Bt-maize and three conventional maize varieties were analyzed together with coarse roots of the Bt-maize. A total of 547 000 sequences were obtained. Library coverage was 100% at the phylum and 99.8% at the genus rank. Although cluster analyses based on relative abundances indicated no differences at higher taxonomic ranks, genera abundances pointed to variety specific differences. Genera-based clustering depended solely on the 49 most dominant genera while the remaining 461 rare genera followed a different selection. A total of 91 genera responded significantly to the different root environments. As a benefit of pyrosequencing, 79 responsive genera were identified that might have been overlooked with conventional cloning sequencing approaches owing to their rareness. There was no indication of bacterial alterations in the rhizosphere of the Bt-maize beyond differences found between conventional varieties. B. thuringiensis-like phylotypes were present at low abundance (0.1% of Bacteria) suggesting possible occurrence of natural Cry proteins in the rhizospheres. Although some genera indicated potential phytopathogenic bacteria in the rhizosphere, their abundances were not significantly different between conventional varieties and Bt-maize. With an unprecedented sensitivity this study indicates that the rhizosphere bacterial community of a GM maize did not respond abnormally to the presence of three insecticidal proteins in the root tissue.     

Multi‐factor climate change effects on insect herbivore performance

The impact of climate change on herbivorous insects can have far‐reaching consequences for ecosystem processes. However, experiments investigating the combined effects of multiple climate change drivers on herbivorous insects are scarce. We independently manipulated three climate change drivers (CO₂, warming, drought) in a Danish heathland ecosystem. The experiment was established in 2005 as a full factorial split‐plot with 6 blocks × 2 levels of CO₂ × 2 levels of warming × 2 levels of drought = 48 plots. In 2008, we exposed 432 larvae (n = 9 per plot) of the heather beetle (Lochmaea suturalis Thomson ), an important herbivore on heather, to ambient versus elevated drought, temperature, and CO₂ (plus all combinations) for 5 weeks. Larval weight and survival were highest under ambient conditions and decreased significantly with the number of climate change drivers. Weight was lowest under the drought treatment, and there was a three‐way interaction between time, CO₂, and drought. Survival was lowest when drought, warming, and elevated CO₂ were combined. Effects of climate change drivers depended on other co‐acting factors and were mediated by changes in plant secondary compounds, nitrogen, and water content. Overall, drought was the most important factor for this insect herbivore. Our study shows that weight and survival of insect herbivores may decline under future climate. The complexity of insect herbivore responses increases with the number of combined climate change drivers.     

Co-expression of nicastrin and presenilin rescues a loss of function mutant of APH-1

gamma-Secretase is an intramembrane-cleaving aspartyl protease complex that mediates the final cleavage of beta-amyloid precursor protein to liberate the neurotoxic amyloid-beta peptide implicated in Alzheimer's disease. The four proteins presenilin (PS), nicastrin (NCT), APH-1, and PEN-2 are sufficient to reconstitute gamma-secretase activity in yeast. Although PS seems to contribute the catalytic core of the gamma-secretase complex, no distinct function could be attributed to the other components so far. In Caenorhabditis elegans, mutation of a glycine to an aspartic acid within a conserved GXXXG motif in the fourth transmembrane domain of APH-1 causes a loss of function phenotype. Surprisingly, we now found that the human homologue APH-1a carrying the equivalent mutation G122D is fully active in yeast co-expressing PS1, NCT, and PEN-2. To address this discrepancy, we expressed APH-1a G122D in HEK293 cells. As reported previously, overexpressed APH-1a G122D was not incorporated into the gamma-secretase complex. Separate overexpression of PS1, NCT, or PEN-2 together with APH-1a G122D allowed the formation of heterodimers lacking the other endogenous components. Only the combined overexpression of PS1 and NCT together with APH-1a G122D facilitated the formation of a fully active gamma-secretase complex. Under these conditions, APH-1a G122D supported the production of normal amounts of Abeta. We conclude that cooperative effects may stabilize a trim-eric complex of APH-1a G122D together with PS1 and NCT. Upon successful complex assembly, the GXXXG motif becomes dispensable for gamma-secretase activity.