The Enigma of the Respiratory Chain Supercomplex

Respiratory chain dysfunction plays an important role in human disease and aging. It is now well established that the individual respiratory complexes can be organized into supercomplexes, and structures for these macromolecular assemblies, determined by electron cryo-microscopy, have been described recently. Nevertheless, the reason why supercomplexes exist remains an enigma. The widely held view that they enhance catalysis by channeling substrates is challenged by both structural and biophysical information. Here, we evaluate and discuss data and hypotheses on the structures, roles, and assembly of respiratory-chain supercomplexes and propose a future research agenda to address unanswered questions.N.G.L. receives support from the Max Planck Society, the Swedish Research Council (2015-00418), and the Knut and Alice Wallenberg foundation. J.H. and J.N.B. are supported by The Medical Research Council (U105663141 to J.H.)

Plant responses to soil inoculation treatments at different life-stages

Plant responses to soil inoculation treatments at different life-stage

Bivariate relationships between plant species richness and the diversity indices.

<p>abundance (a and b), species richness (c and d), Shannon evenness (e and f) and dominance (g and h) for herbivores (left panel) and carnivores (right panel). All response variables were standardized by removing the block effect, ie by substracting from each experimental unit (n = 80) the average value measured in the respective block. Abundance was log10-transformed and evenness logit-transformed. The lines show fitted regression lines from linear models, and solid lines indicate significant diversity effects (p <0.05). The <b>R</b>^<b>2</b> values were taken from the linear models. Diversity indices and the fitted regression lines from the models were back-transformed to the original scale.</p

SEM’s representing plant community effects on arthropod diversity indices.

<p>Effects of plant sown richness, total plant biomass and the presence/absence of the four plant functional groups on abundance (a and b), species richness (c and d), Shannon evenness (e and f) and dominance (g and h) for herbivores (left panels) and carnivores (right panels). The reported path coefficients are standardized, and colored paths are significant at the 0.05 level. Blue paths have a positive path coefficient, whereas red paths have a negative one. We report the p-value for the Chi-square test of the SEM’s along with the p-value for the root mean square error (RMSEA). R^<b>2</b> value for the diversity indices are given in the indices box.</p

Trophic and Non-Trophic Interactions in a Biodiversity Experiment Assessed by Next-Generation Sequencing

<div><p>Plant diversity affects species richness and abundance of taxa at higher trophic levels. However, plant diversity effects on omnivores (feeding on multiple trophic levels) and their trophic and non-trophic interactions are not yet studied because appropriate methods were lacking. A promising approach is the DNA-based analysis of gut contents using next generation sequencing (NGS) technologies. Here, we integrate NGS-based analysis into the framework of a biodiversity experiment where plant taxonomic and functional diversity were manipulated to directly assess environmental interactions involving the omnivorous ground beetle <i>Pterostichus melanarius</i>. Beetle regurgitates were used for NGS-based analysis with universal 18S rDNA primers for eukaryotes. We detected a wide range of taxa with the NGS approach in regurgitates, including organisms representing trophic, phoretic, parasitic, and neutral interactions with <i>P</i>. <i>melanarius</i>. Our findings suggest that the frequency of (i) trophic interactions increased with plant diversity and vegetation cover; (ii) intraguild predation increased with vegetation cover, and (iii) neutral interactions with organisms such as fungi and protists increased with vegetation cover. Experimentally manipulated plant diversity likely affects multitrophic interactions involving omnivorous consumers. Our study therefore shows that trophic and non-trophic interactions can be assessed via NGS to address fundamental questions in biodiversity research.</p></div

Mites as prey and parasites of <i>P</i>. <i>melanarius</i>.

<p>(A) Predatory mite (Trombidiformes: Trombiculidae) in a plot of the Jena-Experiment. (B) Mite isolated from a gut of <i>P</i>. <i>melanarius</i> (C). Phoretic mites (Mesostigmata: Parasitidae) on <i>P</i>. <i>melanarius</i>. Photographs by C. Scherber.</p

Organisms detected with NGS in regurgitates of <i>P</i>. <i>melanarius</i>, sorted by their most likely type of interaction with the beetle.

<p>Organisms detected with NGS in regurgitates of <i>P</i>. <i>melanarius</i>, sorted by their most likely type of interaction with the beetle.</p

Effects of plant species richness and plant functional diversity on detection frequency of abundant OTUs detected in regurgitates of <i>P</i>. <i>melanarius</i>.

<p>The six panels show the three kingdoms (Plantae, Animalia, and Fungi). Points represent OTUs, aggregated at family level, that were detected in at least two levels of plant species richness. Lines (smoother span = 1.6) show least-squares fits for illustrative purposes only.</p

Effects of plant species richness, plant functional diversity, and percentage vegetation cover on feeding interactions and neutral interactions detected in regurgitates of <i>P</i>. <i>melanarius</i>.

<p>Points represent individual plots and are scaled based on the logarithm of the number of sequences, blue lines show GLM predictions, blue polygons show 95% confidence intervals for effects with p<0.05, red lines and red polygons refer to GLMs weighted by the number of sequences. A) Total number of feeding interactions including prey and plant taxa, B) feeding interactions involving plant taxa, C) feeding interactions involving total prey taxa, D) feeding interactions involving intraguild predation, and E) neutral interactions.</p

Summary of generalized linear model results on the effect of plant species richness, plant functional diversity and percent vegetation cover on the number of OTUs detected in each interaction group.

<p>Summary of generalized linear model results on the effect of plant species richness, plant functional diversity and percent vegetation cover on the number of OTUs detected in each interaction group.</p