bluuebunny/crossref_metadata_2025_split huggingface dataset:
Robust, Universal Tree Balance Indices
Authors: Lemant Jeanne , Sueur Cécile Le , Manojlović Veselin , Noble Robert 
Published: August 2021

AbstractBalance indices that quantify the symmetry of branching events and the compactness of trees are widely used to compare evolutionary processes or tree-generating algorithms. Yet existing indices have important shortcomings, including that they are unsuited to the tree types commonly used to describe the evolution of tumours, microbial populations, and cell lines. The contributions of this article are twofold. First, we define a new class of robust, universal tree balance indices. These indices take a form similar to Colless’ index but account for node sizes, are defined for trees with any degree distribution, and enable more meaningful comparison of trees with different numbers of leaves. Second, we show that for bifurcating and all other full m-ary cladograms (in which every internal node has the same out-degree), one such Colless-like index is equivalent to the normalised reciprocal of Sackin’s index. Hence we both unify and generalise the two most popular existing tree balance indices. Our indices are intrinsically normalised and can be computed in linear time. We conclude that these more widely applicable indices have potential to supersede those in current use.
Structural Analysis of Receptor Binding Domain Mutations in SARS-CoV-2 Variants of Concern that Modulate ACE2 and Antibody Binding
Authors: Mannar Dhiraj , Saville James W , Zhu Xing , Srivastava Shanti S. , Berezuk Alison M. , Zhou Steven , Tuttle Katharine S. , Kim Andrew , Li Wei , Dimitrov Dimiter S. , Subramaniam Sriram 
Published: August 2021

SummaryThe recently emerged SARS-CoV-2 South African (B. 1.351) and Brazil/Japan (P.1) variants of concern (VoCs) include a key mutation (N501Y) found in the UK variant that enhances affinity of the spike protein for its receptor, ACE2. Additional mutations are found in these variants at residues 417 and 484 that appear to promote antibody evasion. In contrast, the Californian VoCs (B.1.427/429) lack the N501Y mutation, yet exhibit antibody evasion. We engineered spike proteins to express these RBD VoC mutations either in isolation, or in different combinations, and analyzed the effects using biochemical assays and cryo-EM structural analyses. Overall, our findings suggest that the emergence of new SARS-CoV-2 variant spikes can be rationalized as the result of mutations that confer either increased ACE2 affinity, increased antibody evasion, or both, providing a framework to dissect the molecular factors that drive VoC evolution.
The impact of genetic modifiers on variation in germline mutation rates within and among human populations
Authors: Milligan William R. , Amster Guy , Sella Guy 
Published: August 2021

AbstractMutation rates and spectra differ among human populations. Here, we examine whether this variation could be explained by evolution at mutation modifiers. To this end, we consider genetic modifier sites at which mutations, “mutator alleles”, increase genome-wide mutation rates and model their evolution under purifying selection due to the additional deleterious mutations that they cause, genetic drift, and demographic processes. We solve the model analytically for a constant population size and characterize how evolution at modifier sites impacts variation in mutation rates within and among populations. We then use simulations to study the effects of modifier sites under a plausible demographic model for Africans and Europeans. When comparing populations that evolve independently, weakly selected modifier sites (2Nes ≈ 1), which evolve slowly, contribute the most to variation in mutation rates. In contrast, when populations recently split from a common ancestral population, strongly selected modifier sites (2Nes ≫ 1), which evolve rapidly, contribute the most to variation between them. Moreover, a modest number of modifier sites (e.g., 10 per mutation type in the standard classification into 96 types) subject to moderate to strong selection (2Nes > 1) could account for the variation in mutation rates observed among human populations. If such modifier sites indeed underlie differences among populations, they should also cause variation in mutation rates within populations and their effects should be detectable in pedigree studies.
Evolutionarily conserved genetic interactions between nphp-4 and bbs-5 mutations exacerbate ciliopathy phenotypes
Authors: Bentley-Ford Melissa R. , LaBonty Melissa , Thomas Holly R. , Haycraft Courtney J. , Scott Mikyla , LaFayette Cameron , Croyle Mandy J. , Parant John M. , Yoder Bradley K. 
Published: August 2021

AbstractPrimary cilia are sensory and signaling hubs with a protein composition that is distinct from the rest of the cell due to the barrier function of the transition zone (TZ) at the base of the cilium. Protein transport across the TZ is mediated in part by the BBSome, and mutations disrupting TZ and BBSome proteins cause human ciliopathy syndromes. Ciliopathies have phenotypic variability even among patients with identical genetic variants, suggesting a role for modifier loci. To identify potential ciliopathy modifiers, we performed a mutagenesis screen on nphp-4 mutant C. elegans and uncovered a novel allele of bbs-5. Nphp-4;bbs-5 double mutant worms have phenotypes not observed in either individual mutant strain. To test whether this genetic interaction is conserved, we also analyzed zebrafish and mice mutants. While Nphp4 mutant zebrafish appeared overtly normal, Bbs5 mutants exhibited scoliosis. When combined, Nphp4;Bbs5 double mutant zebrafish did not exhibit synergistic effects, but the lack of a phenotype in Nphp4 mutants makes interpreting these data difficult. In contrast, viable Nphp4;Bbs5 double mutant mice were not obtained and there were fewer mice than expected carrying three mutant alleles. Additionally, postnatal loss of Bbs5 in mice using a conditional allele compromised survival when combined with a Nphp4 allele. As cilia are formed in the double mutant mice, the exacerbated phenotype is likely a consequence of disrupted ciliary signaling. Collectively, these data support an evolutionarily conserved genetic interaction between Bbs5 and Nphp4 alleles that may contribute to the variability in ciliopathy phenotypes.
A quantitative mapping approach to identify direct interactions within complexomes
Authors: Trepte Philipp , Secker Christopher , Choi Soon Gang , Olivet Julien , Ramos Eduardo Silva , Cassonnet Patricia , Golusik Sabrina , Zenkner Martina , Beetz Stephanie , Sperling Marcel , Wang Yang , Hao Tong , Spirohn Kerstin , Twizere Jean-Claude , Calderwood Michael A. , Hill David E. , Jacob Yves , Vidal Marc , Wanker Erich E. 
Published: August 2021

ABSTRACTComplementary methods are required to fully characterize all protein complexes, or the complexome, of a cell. Affinity purification coupled to mass-spectrometry (AP-MS) can identify the composition of complexes at proteome-scale. However, information on direct contacts between subunits is often lacking. In contrast, solving the 3D structure of protein complexes can provide this information, but structural biology techniques are not yet scalable for systematic, proteome-wide efforts. Here, we optimally combine two orthogonal high-throughput binary interaction assays, LuTHy and N2H, and demonstrate that their quantitative readouts can be used to differentiate direct interactions from indirect associations within multiprotein complexes. We also show that LuTHy allows accurate distance measurements between proteins in live cells and apply these findings to study the impact of the polyglutamine expansion mutation on the structurally unresolved N-terminal domain of Huntingtin. Thus, we present a new framework based on quantitative interaction assays to complement structural biology and AP-MS techniques, which should help to provide first-approximation contact maps of multiprotein complexes at proteome-scale.Graphical Abstract
MicroRNA-27a-5p inhibits proliferation, migration and invasion and promotes apoptosis of Wilms tumor cell by targeting PBOV1
Authors: Guo Zheng-Tuan , Yu Qiang , Miao Chunlin , Ge Wenan , Li Peng 
Published: August 2021

AbstractWilms tumor is the most common type of renal tumor in children. MicroRNAs (miRNA) are small non-coding RNAs that play crucial regulatory roles in tumorigenesis. We aimed to study the expression profile and function of miR-27a-5p in Wilms tumor. MiR-27a-5p expression was downregulated in human Wilms tumor tissues. Functionally, overexpression of miR-27a-5p promoted cell apoptosis of Wilms tumor cells. Furthermore, upregulated miR-27a-5p delayed xenograft Wilms tumor tumorigenesis in vivo. Bioinformatics analysis predicted miR-27-5p directly targeted to the 3’-untranslated region (UTR) of PBOV1 and luciferase reporter assay confirmed the interaction between miR-27a-5p and PBOV1. The function of PBOV1 in Wilms tumor was evaluated in vitro and knockdown of PBOV1 dampened cell migration. In addition, overexpression of PBOV1 antagonized the tumor-suppressive effect of miR-27a-5p in Wilms tumor cells. Collectively, our findings reveal the regulatory axis of miR-27-5p/PBOV1 in Wilms tumor and miR-27a-5p might serve as a novel therapeutic target in Wilms tumor.
Drivers of genomic landscapes of differentiation acrossPopulusdivergence gradient
Authors: Shang Huiying , Rendón-Anaya Martha , Paun Ovidiu , Field David L , Hess Jaqueline , Vogl Claus , Liu Jianquan , Ingvarsson Pär K. , Lexer Christian , Leroy Thibault 
Published: August 2021

AbstractSpeciation, the continuous process by which new species form, is often investigated by looking at the variation of nucleotide diversity and differentiation across the genome (hereafter genomic landscapes). A key challenge lies in how to determine the main evolutionary forces at play shaping these patterns. One promising strategy, albeit little used to date, is to comparatively investigate these genomic landscapes as a progression through time by using a series of species pairs along a divergence gradient. Here, we resequenced 201 whole-genomes from eight closely relatedPopulusspecies, with pairs of species at different stages along the divergence gradient to learn more about speciation processes. Using population structure and ancestry analyses, we document extensive introgression between some species pairs, especially those with parapatric distributions. We further investigate genomic landscapes, focusing on within-species (nucleotide diversity and recombination rate) and among-species (relative and absolute divergence) summary statistics of diversity and divergence. We observe highly conserved patterns of genomic divergence across species pairs. Independent of the stage across the divergence gradient, we find support for signatures of linked selection (i.e., the interaction between natural selection and genetic linkage) in shaping these genomic landscapes, along with gene flow and standing genetic variation. We highlight the importance of investigating genomic patterns on multiple species across a divergence gradient and discuss prospects to better understand the evolutionary forces shaping the genomic landscapes of diversity and differentiation.
Structural remodeling of SARS-CoV-2 spike protein glycans reveals the regulatory roles in receptor binding affinity
Authors: Hsu Yen-Pang , Mukherjee Debopreeti , Shchurik Vladimir , Makarov Alexey , Mann Benjamin F. 
Published: August 2021

AbstractGlycans of the SARS-CoV-2 spike protein are speculated to play functional roles in the infection processes as they extensively cover the protein surface and are highly conserved across the variants. To date, the spike protein has become the principal target for vaccine and therapeutic development while the exact effects of its glycosylation remain elusive. Experimental reports have described the heterogeneity of the spike protein glycosylation profile. Subsequent molecular simulation studies provided a knowledge basis of the glycan functions. However, there are no studies to date on the role of discrete glycoforms on the spike protein pathobiology. Building an understanding of its role in SARS-CoV-2 is important as we continue to develop effective medicines and vaccines to combat the disease. Herein, we used designed combinations of glycoengineering enzymes to simplify and control the glycosylation profile of the spike protein receptor-binding domain (RBD). Measurements of the receptor binding affinity revealed the regulatory effects of the RBD glycans. Remarkably, opposite effects were observed from differently remodeled glycans, which presents a potential strategy for modulating the spike protein behaviors through glycoengineering. Moreover, we found that the reported anti-SARS-CoV-(2) antibody, S309, neutralizes the impact of different RBD glycoforms on the receptor binding affinity. Overall, this work reports the regulatory roles that glycosylation plays in the interaction between the viral spike protein and host receptor, providing new insights into the nature of SARS-CoV-2. Beyond this study, enzymatic remodeling of glycosylation offers the opportunity to understand the fundamental role of specific glycoforms on glycoconjugates across molecular biology.Covert art LegendsThe glycosylation of the SARS-CoV-2 spike protein receptor-binding domain has regulatory effects on the receptor binding affinity. Sialylation or not determines the “stabilizing” or “destabilizing” effect of the glycans. (Protein structure model is adapted from Protein Data Bank: 6moj. The original model does not contain the glycan structure.)SignificanceGlycans extensively cover the surface of SARS-CoV-2 spike (S) protein but the relationships between the glycan structures and the protein pathological behaviors remain elusive. Herein, we simplified and harmonized the glycan structures in the S protein receptor-binding domain and reported their regulatory roles in human receptor interaction. Opposite regulatory effects were observed and were determined by discrete glycan structures, which can be neutralized by the reported S309 antibody binding to the S protein. This report provides new insight into the mechanism of SARS-CoV-2 S protein infection as well as S309 neutralization.
Characterization and computational simulation of human Syx, a RhoGEF implicated in glioblastoma
Authors: Boyd Ryan J , Olson Tien L. , Zook James D. , Aceves Manuel , Stein Derek , Lin Wan-Hsin , Craciunescu Felicia M. , Hansen Debra T. , Anastasiadis Panos Z. , Singharoy Abhishek , Fromme Petra 
Published: August 2021

AbstractStructural discovery of guanine nucleotide exchange factor (GEF) protein complexes is likely to become increasingly relevant with the development of new therapeutics targeting small GTPases and development of new classes of small molecules that inhibit protein-protein interactions. Syx (also known as PLEKHG5 in humans) is a RhoA GEF implicated in the pathology of glioblastoma (GBM). Here we investigated protein expression and purification of ten different human Syx constructs and performed biophysical characterizations and computational studies that provide insights into why expression of this protein was previously intractable. We show that human Syx can be expressed and isolated and Syx is folded as observed by circular dichroism (CD) spectroscopy and actively binds to RhoA as determined by co-elution during size exclusion chromatography (SEC). This characterization may provide critical insights into the expression and purification of other recalcitrant members of the large class of oncogenic — Diffuse B-cell lymphoma (Dbl) homology GEF proteins. In addition, we performed detailed homology modeling and molecular dynamics simulations on the surface of a physiologically realistic membrane. These simulations reveal novel insights into GEF activity and allosteric modulation by the plekstrin homology (PH) domain. These newly revealed interactions between the GEF PH domain and the membrane embedded region of RhoA support previously unexplained experimental findings regarding the allosteric effects of the PH domain from numerous activity studies of Dbl homology GEF proteins. This work establishes new hypotheses for structural interactivity and allosteric signal modulation in Dbl homology RhoGEFs.
Frameshifting at collided ribosomes is modulated by elongation factor eEF3 and by Integrated Stress Response regulators Gcn1 and Gcn20
Authors: Houston Lisa , Platten Evan , Connelly Sara , Wang Jiyu , Grayhack Elizabeth J. 
Published: August 2021

AbstractRibosome stalls can result in ribosome collisions that elicit quality control responses, one function of which is to prevent frameshifting by the stalled ribosome, an activity that entails interaction of the conserved yeast protein Mbf1 with uS3 on colliding ribosomes. However, the full spectrum of factors that mediate frameshifting during ribosome collisions is unknown. To delineate such factors in the yeastSaccharomyces cerevisiae, we used genetic selections for mutants that either suppress or increase frameshifting from a known ribosome stall site, CGA codon repeats. We show that the general translation elongation factor eEF3 promotes frameshifting, while Integrated Stress Response (ISR) pathway components Gcn1 and Gcn20 suppress frameshifting. We found a mutant form of eEF3 that specifically suppressed frameshifting, but not translation inhibition by CGA codons. Thus, we infer that frameshifting at collided ribosomes requires eEF3, which facilitates tRNA-mRNA translocation and E-site tRNA release in yeast and other single cell organisms. By contrast, we found that removal of either Gcn1 or Gcn20, which bind collided ribosomes with Mbf1, increased frameshifting. Thus, we conclude that frameshifting is suppressed by Gcn1 and Gcn20, although these effects are not mediated through activation of the ISR. Furthermore, we examined the relationship of eEF3-mediated frameshifting to other quality control mechanisms, finding that the eEF3-mediated frameshifting competes with No-Go decay, Mbf1 and Gcn1/20. Thus, these results provide evidence of a direct link between translation elongation and frameshifting at collided ribosomes, as well as evidence that frameshifting competes with other quality control pathways that act on collided ribosomes.
Using herbarium samples for NGS methods – a methodological comparison
Authors: Marinček Pia , Wagner Natascha D. , Tomasello Salvatore 
Published: August 2021

AbstractHerbaria harbor a tremendous amount of plant specimens that are rarely used for plant systematic studies. The main reason is the difficulty to extract a decent quantity of good quality DNA from the preserved plant material. While the extraction of ancient DNA in animals is well established, studies including old plant material are still underrepresented. In our study we compared the standard Qiagen DNeasy Plant Mini Kit and a specific PTB-DTT protocol on two different plant genera (Xanthium L. and Salix L.). The included herbarium material covered about two centuries of plant collections. A selected subset of samples was used for a standard library preparation as well as a target enrichment approach. The results revealed that PTB-PTT resulted in higher quantity and quality regarding DNA yield. For relatively recent herbarium specimens, and despite the lower overall yield of DNA, the Qiagen Kit resulted in better sequencing results regarding the number of filtered and mapped reads. We were able to successfully sequence a sample from 1820 and conclude that it is possible to include old herbarium specimens in NGS approaches. This opens a treasure box for phylogenomic research.
Impact of vitamin B12 on rhamnose metabolism, stress defense and in-vitro virulence ofListeria monocytogenes
Authors: Zeng Zhe , Wijnands Lucas M. , Boeren Sjef , Smid Eddy J. , Notebaart Richard A. , Abee Tjakko 
Published: August 2021

AbstractListeria monocytogenesis a facultative anaerobe which can cause a severe food-borne infection known as listeriosis. Rhamnose is a deoxyhexose sugar abundant in a range of environments, including the human intestine, and can be degraded byL. monocytogenesin aerobic and anaerobic conditions into lactate, acetate and 1,2-propanediol. Our previous study showed that addition of vitamin B12 stimulates anaerobic growth ofL. monocytogeneson rhamnose due to the activation of bacterial microcompartment (BMC)-dependent 1,2-propanediol utilization with concomitant production of propionate and propanol. Notably, anaerobic propanediol metabolism has been linked to virulence of enteric pathogens includingSalmonellaspp. andL. monocytogenes. In this study we investigate the impact of B12 on aerobic and anerobic growth ofL. monocytogeneson rhamnose, and observed growth stimulation andpduBMC activation only in anaerobically grown cells with B12 added to the medium. Comparative Caco-2 virulence assays, showed that thesepduBMC induced cells have significantly higher translocation efficiency compared to aerobically grown cells (without and with added B12) and non-induced anaerobically grown cells, while adhesion and invasion capacity is similar for all cells. Comparative proteomics analysis showed specific and overlapping responses linked to metabolic shifts, activation of stress defense proteins and virulence factors, with RNA polymerase sigma factor SigL; teichoic acids export ATP-binding protein, TagH; DNA repair and protection proteins RadA and DPS; and glutathione synthase GshAB previously linked to activation of virulence response inL. monocytogenes, uniquely upregulated in anaerobically rhamnose grownpduBMC induced cells. Our results shed new light into B12 impact onL. monocytogenescompetitive fitness and virulence.
Sex differences in deleterious genetic variants in a haplodiploid social insect
Authors: Miller Sara E. , Sheehan Michael J. 
Published: August 2021

AbstractDeleterious variants are selected against but can linger in populations at low frequencies for long periods of time, decreasing fitness and contributing to disease burden in humans and other species. Deleterious variants occur at low frequency but distinguishing deleterious variants from low frequency neutral variation is challenging based on population genetics data. As a result, we have little sense of the number and identity of deleterious variants in wild populations. For haplodiploid species, it has been hypothesized that deleterious alleles will be directly exposed to selection in haploid males, but selection can be masked in diploid females due to partial or complete dominance, resulting in more efficient purging of deleterious mutations in males. Therefore, comparisons of the differences between haploid and diploid genomes from the same population may be a useful method for inferring rare deleterious variants. This study provides the first formal test of this hypothesis. Using wild populations of Northern paper wasps (Polistes fuscatus), we find that males have fewer overall variants, and specifically fewer missense and nonsense variants, than females from the same population. Allele frequency differences are especially pronounced for rare missense and nonsense mutations and these differences lead to a lower genetic load in males than females. Based on these data we estimate that a large number of highly deleterious mutations are segregating in the paper wasp population. Stronger selection against deleterious alleles in haploid males may have implications for adaptation in other haplodiploid insects and provides evidence that wild populations harbor abundant deleterious variants.