Cristae are infoldings of the mitochondrial inner membrane jutting into the organelle’s innermost compartment from narrow stems at their base called crista junctions. They are emblematic of aerobic ...mitochondria, being the fabric for the molecular machinery driving cellular respiration. Electron microscopy revealed that diverse eukaryotes possess cristae of different shapes. Yet, crista diversity has not been systematically examined in light of our current knowledge about eukaryotic evolution. Since crista form and function are intricately linked, we take a holistic view of factors that may underlie both crista diversity and the adherence of cristae to a recognizable form. Based on electron micrographs of 226 species from all major lineages, we propose a rational crista classification system that postulates cristae as variations of two general morphotypes: flat and tubulo-vesicular. The latter is most prevalent and likely ancestral, but both morphotypes are found interspersed throughout the eukaryotic tree. In contrast, crista junctions are remarkably conserved, supporting their proposed role as diffusion barriers that sequester cristae contents. Since cardiolipin, ATP synthase dimers, the MICOS complex, and dynamin-like Opa1/Mgm1 are known to be involved in shaping cristae, we examined their variation in the context of crista diversity. Moreover, we have identified both commonalities and differences that may collectively be manifested as diverse variations of crista form and function.
In this review, Pánek et al. have surveyed crista diversity found in mitochondria from disparate organisms, identifying persistent shapes of cristae and discussing possible molecular mechanisms behind their varied morphology.
Landslides in deglaciated and deglaciating mountains represent a major hazard, but their distribution at the spatial scale of entire mountain belts has rarely been studied. Traditional models of ...landslide distribution assume that landslides are concentrated in the steepest, wettest, and most tectonically active parts of the orogens, where glaciers reached their greatest thickness. However, based on mapping large landslides (> 0.9 km
) over an unprecedentedly large area of Southern Patagonia (~ 305,000 km
), we show that the distribution of landslides can have the opposite trend. We show that the largest landslides within the limits of the former Patagonian Ice Sheet (PIS) cluster along its eastern margins occupying lower, tectonically less active, and arid part of the Patagonian Andes. In contrast to the heavily glaciated, highest elevations of the mountain range, the peripheral regions have been glaciated only episodically, leaving a larger volume of unstable sedimentary and volcanic rocks that are subject to ongoing slope instability.
Amoebozoa is the eukaryotic supergroup sister to Obazoa, the lineage that contains the animals and Fungi, as well as their protistan relatives, and the breviate and apusomonad flagellates. Amoebozoa ...is extraordinarily diverse, encompassing important model organisms and significant pathogens. Although amoebozoans are integral to global nutrient cycles and present in nearly all environments, they remain vastly understudied. We present a robust phylogeny of Amoebozoa based on broad representative set of taxa in a phylogenomic framework (325 genes). By sampling 61 taxa using culture-based and single-cell transcriptomics, our analyses show two major clades of Amoebozoa, Discosea, and Tevosa. This phylogeny refutes previous studies in major respects. Our results support the hypothesis that the last common ancestor of Amoebozoa was sexual and flagellated, it also may have had the ability to disperse propagules from a sporocarp-type fruiting body. Overall, the main macroevolutionary patterns in Amoebozoa appear to result from the parallel losses of homologous characters of a multiphase life cycle that included flagella, sex, and sporocarps rather than independent acquisition of convergent features.
The type 2 secretion system (T2SS) is present in some Gram-negative eubacteria and used to secrete proteins across the outer membrane. Here we report that certain representative heteroloboseans, ...jakobids, malawimonads and hemimastigotes unexpectedly possess homologues of core T2SS components. We show that at least some of them are present in mitochondria, and their behaviour in biochemical assays is consistent with the presence of a mitochondrial T2SS-derived system (miT2SS). We additionally identified 23 protein families co-occurring with miT2SS in eukaryotes. Seven of these proteins could be directly linked to the core miT2SS by functional data and/or sequence features, whereas others may represent different parts of a broader functional pathway, possibly also involving the peroxisome. Its distribution in eukaryotes and phylogenetic evidence together indicate that the miT2SS-centred pathway is an ancestral eukaryotic trait. Our findings thus have direct implications for the functional properties of the early mitochondrion.
The flysch nappe outliers represent a structural setting prone to the development of deep-seated gravitational slope deformations (DSGSDs). The study area of the Palkovické hůrky hills represents an ...isolated outlier of the Carpathians flysch nappes, Czech Republic. Geomorphological mapping based on field surveys and interpretation of LiDAR data reveals the occurrence of various types of slope deformations, including two DSGSDs. With the aim of detecting the main controlling factors of the DSGSDs, a multiapproach investigation combining surface and underground studies has been performed. Structural measurement points to a brachysynclinal structure composed of jointed and lithologically diverse strata with step-like topography. High-resolution LiDAR data suggest strong tectonic disruption caused by conjugated transtensional and en echelon tectonic faults controlling the course of slope segments, river valleys and landslide scarps. Four specific localities have been subjected to geophysical surveying. Kilometre-scale electrical resistivity tomography (ERT) profiles that have depths of penetration reaching the limits of the method (>150 m) were acquired across the gravitationally deformed nappe outlier. The data show the overall structural conditions of the nappe outlier consisting of alternating lithological units affected by folds and fault zones. A local subordinate anticline within the central part of the brachysynclinal structure has controlled the origin of the most morphologically pronounced DSGSDs. Other large-scale DSGSDs related to the inherited fault system potentially affect the entire N/NW segment of the studied elevation. Data integration indicate that structural conditions, including lithological boundaries, tectonic disruption and local folding to be the main controlling factors of the DSGSDs evolution.
•Interpretation of the deep (>150 m) internal structure of flysch nappe outliers revealed by kilometre-scale ERT sections•Distribution of landslides described by LiDAR/field mapping and ERT sounding•Major landslides and DSGSDs located along faults and/or local fold structures•Specific structural predispositions control the origin of DSGSDs even in terrain with subdued local relief
ZapE/Afg1 is a component of the inner cell membrane of some eubacteria and the inner mitochondrial membrane of eukaryotes. This protein is involved in FtsZ-dependent division of eubacteria. In the ...yeast and human mitochondrion, ZapE/Afg1 likely interacts with Oxa1 and facilitates the degradation of mitochondrion-encoded subunits of respiratory complexes. Furthermore, the depletion of ZapE increases resistance to apoptosis, decreases oxidative stress tolerance, and impacts mitochondrial protein homeostasis. It remains unclear whether ZapE is a multifunctional protein, or whether some of the described effects are just secondary phenotypes. Here, we have analyzed the functions of ZapE in Trypanosoma brucei, a parasitic protist, and an important model organism. Using a newly developed proximity-dependent biotinylation approach (BioID2), we have identified the inner mitochondrial membrane insertase Oxa1 among three putative interacting partners of ZapE, which is present in two paralogs. RNAi-mediated depletion of both ZapE paralogs likely affected the function of respiratory complexes I and IV. Consistently, we show that the distribution of mitochondrial ZapE is restricted only to organisms with Oxa1, respiratory complexes, and a mitochondrial genome. We propose that the evolutionarily conserved interaction of ZapE with Oxa1, which is required for proper insertion of many inner mitochondrial membrane proteins, is behind the multifaceted phenotype caused by the ablation of ZapE.
Oxygen plays a crucial role in energetic metabolism of most eukaryotes. Yet adaptations to low-oxygen concentrations leading to anaerobiosis have independently arisen in many eukaryotic lineages, ...resulting in a broad spectrum of reduced and modified mitochondrion-related organelles (MROs). In this study, we present the discovery of two new class-level lineages of free-living marine anaerobic ciliates, Muranotrichea, cl. nov. and Parablepharismea, cl. nov., that, together with the class Armophorea, form a major clade of obligate anaerobes (APM ciliates) within the Spirotrichea, Armophorea, and Litostomatea (SAL) group. To deepen our understanding of the evolution of anaerobiosis in ciliates, we predicted the mitochondrial metabolism of cultured representatives from all three classes in the APM clade by using transcriptomic and metagenomic data and performed phylogenomic analyses to assess their evolutionary relationships. The predicted mitochondrial metabolism of representatives from the APM ciliates reveals functional adaptations of metabolic pathways that were present in their last common ancestor and likely led to the successful colonization and diversification of the group in various anoxic environments. Furthermore, we discuss the possible relationship of Parablepharismea to the uncultured deep-sea class Cariacotrichea on the basis of single-gene analyses. Like most anaerobic ciliates, all studied species of the APM clade host symbionts, which we propose to be a significant accelerating factor in the transitions to an obligately anaerobic lifestyle. Our results provide an insight into the evolutionary mechanisms of early transitions to anaerobiosis and shed light on fine-scale adaptations in MROs over a relatively short evolutionary time frame.
•Discovery and cultivation of two new classes of marine ciliates thriving in anoxia•Phylogenomics reveals a major clade of obligate anaerobes in ciliates•Novel insights into evolution of mitochondrial metabolism in anaerobic eukaryotes•Transitions to obligate anaerobiosis might be facilitated by prokaryotic symbionts
Numerous eukaryotes have switched to anaerobiosis, variously reducing their mitochondrial metabolism. Rotterová et al. describe two new classes of obligately anaerobic ciliates with prokaryotic symbionts and reduced mitochondria with unique pathways for energetic metabolism, introducing possible mechanisms of transitions to obligate anaerobiosis.
Abstract
The discovery that the protist Monocercomonoides exilis completely lacks mitochondria demonstrates that these organelles are not absolutely essential to eukaryotic cells. However, the degree ...to which the metabolism and cellular systems of this organism have adapted to the loss of mitochondria is unknown. Here, we report an extensive analysis of the M. exilis genome to address this question. Unexpectedly, we find that M. exilis genome structure and content is similar in complexity to other eukaryotes and less “reduced” than genomes of some other protists from the Metamonada group to which it belongs. Furthermore, the predicted cytoskeletal systems, the organization of endomembrane systems, and biosynthetic pathways also display canonical eukaryotic complexity. The only apparent preadaptation that permitted the loss of mitochondria was the acquisition of the SUF system for Fe–S cluster assembly and the loss of glycine cleavage system. Changes in other systems, including in amino acid metabolism and oxidative stress response, were coincident with the loss of mitochondria but are likely adaptations to the microaerophilic and endobiotic niche rather than the mitochondrial loss per se. Apart from the lack of mitochondria and peroxisomes, we show that M. exilis is a fully elaborated eukaryotic cell that is a promising model system in which eukaryotic cell biology can be investigated in the absence of mitochondria.
River-damming by landslides is a widespread phenomenon around the world. Recent advances in remote sensing technology and the rising commercial availability of their products enable the assemblage of ...increasingly more complete inventories and improve monitoring efforts. On the ground, multi-method dating campaigns enhance our understanding of the timelines of dam formation and failure. In comparison to single-dating methods, they reduce uncertainty by using different materials from the landslide deposit, facilitate the advantages of each method, and consider the deposit and the source area. They can pin dates on the time of lake drainage where backwater sediments are included in the dating campaign and thus inform about dam longevity. Geophysical methods provide non-invasive and rapid methods to investigate the properties and interior conditions of landslide dams. By identifying, e.g. evolving zones of weakness and saturation they can aid in the monitoring of a dam in addition to providing information on interior stratification for scientific research. To verify results from geophysical campaigns, and to add details of dam interior structures and geotechnical properties, knowledge of their sedimentology is essential. This information is gathered at sections from breached dams, other (partially) eroded landslide deposits, and through laboratory testing of sampled material. Combining the knowledge gained from all these methods with insights from blast-fill and embankment dam construction, physical and numerical modelling in multi-disciplinary research projects is the way forward in landslide dam research, assessment and monitoring. This review offers a broad, yet concise overview of the state-of-the-art in the aforementioned research fields. It completes the review of Fan et al. (2020) on the formation and impact on landslide dams.
The undercut slope of the Skalická Strážnice/Vrchy hill situated in the piedmont of the Carpathian Mountains (Czech Republic) is a regional landslide “hotspot”, notorious for its repeated recent and ...historical sliding reactivations. We performed tree-ring analysis of a large number (n=274) of broad-leaved trees to reconstruct the spatio-temporal patterns of landslide reactivation for a period spanning more than one hundred years (1884–2011). Although tree rings of broad-leaved trees are less-reliable archives of landslide activity than those of conifers, the application of a methodology based on the weighting of disturbance signals within eccentricity series generated a usable dataset of sliding activity affecting anisotropic flysch bedrock. Although some known landslide years could not be found (or were expressed by only weak signals) in the reconstructed dataset, the majority of landslide events reconstructed from the tree-ring series coincide with hydrometeorological data, revealing a correlation with heavy summer rainfalls lasting from two to ten days. The spatial distribution of landslide recurrence derived from the tree-ring records together with electrical resistivity tomography and a kinematic analysis of slope failures suggest a close link between the concentration of landslide activity and the presence of faulted or fractured flysch bedrock.
•Presentation of an active landslide undercutted by a river.•A new dendrogeomorphic method based on analysis of broad-leaved trees is presented.•Results of analysis correspond with morphological features of the landslide.•Analysis of triggering factors is presented.
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