Latest Publications
Structural basis and evolutionary pathways of glycerol-1-phosphate transport in marine bacteria
Ning Wang, Linda M. Westermann, Mingyu Li, Chun-Yang Li, Andrew R. J. Murphy, Zengtian Gu, Eleonora Silvano, Claudia A. Blindauer, Ian D. E. A., Yu-Zhong Zhang, David J. Scanlan, Yin Chen
All cells use lipid membranes to maintain cellular integrity and function, though Archaea utilize lipids composed of glycerol-1-phosphate (G1P), while Bacteria and Eukaryotes use glycerol-3-phosphate (G3P). Given that Archaea contribute significantly to global marine biomass, accounting for 0.3 gigatonnes (Gt) of carbon in the oceans, we aimed to uncover how archaeal G1P is recycled by marine microorganisms. Through a multidisciplinary approach combining microbiology, biochemistry, and structural biology, we identified a G1P transporter in marine bacteria, which we named GpxB. Phylogenetic analysis revealed that GpxB belongs to the organic phosphonate transporter (PhnT) family and is widely distributed in the marine microbiome, found in approximately 5 to 10% of microbial cells in surface marine waters. Strikingly, we also identified a second G1P transporter, UgpB, that is known to transport G3P and belongs to the carbohydrate uptake transporter-1 (CUT1) family, in the model bacterium Phaeobacter sp. MED193. To explore the evolutionary pathways that led to the formation of G1P binding sites in both the PhnT and CUT1 families, we determined the structures of GpxB and UgpB bound to G1P and G3P. Using structure-guided mutagenesis and a comparative analysis of the binding pockets within the PhnT and CUT1 families, we traced their evolutionary trajectories, highlighting the distinct strategies through which G1P-binding sites developed in these two protein families.
Natural variation modifies centromere-proximal meiotic crossover frequency and segregation distortion in Arabidopsis thaliana
Nicola Gorringe , Stephanie Topp , Robin Burns , Sota Yamaguchi , Fernando ARabanal , Joiselle B Fernandes , Detlef Weigel , Tetsuji Kakutani , Matthew Naish , Ian R Henderson
Eukaryotic centromeres mediate chromosome segregation during cell division. Plant centromeres are loaded with CENH3-variant nucleosomes, which direct kinetochore formation and spindle-microtubule interaction. Centromeres are frequently composed of megabase-scale satellite repeat arrays, or retrotransposon nests. In monocentric genomes, such as the model plant Arabidopsis thaliana, pericentromeric heterochromatin surrounds the CENH3-occupied satellite arrays. A zone of suppressed meiotic crossover recombination contains the centromere and extends into the pericentromeres. Here, we explore how natural variation in Arabidopsis influences centromere-proximal crossover frequency and segregation distortion when centromeres are heterozygous. We used fluorescent crossover reporters to quantify the effect of genetic variation on centromere-proximal recombination in 12 F1 hybrids between the reference strain Col-0 and nonreference accessions that captured Eurasian and relict diversity, and in total, we measured 3,037,802 meioses. The majority of the F1 hybrids (49 of 60) had significantly higher or lower centromere-proximal crossover frequency than inbreds. We relate hybrid crossover frequencies to patterns of nucleotide diversity and centromeric structural variation, and in a subset of 7 accessions, to epigenetic patterns of CENH3 enrichment and DNA methylation. Using linear modeling, we observed that chromosome and accession, and their interaction, together explained 85% of variation in crossover frequency, consistent with cis- and trans-acting modifying effects. The fluorescent reporters also allow segregation distortion through meiosis to be quantified between hybrids and inbreds. We observed a minority of hybrids (18 of 60) with distorted segregation through meiosis compared to inbreds, which occurred with or without a simultaneous change to centromere-proximal crossover frequency. Linear modeling revealed that 56% of variation in segregation distortion is explained by chromosome and accession, but with a stronger effect of accession compared to crossover frequency. We discuss how Arabidopsis centromeric structural heterozygosity may modify recombination and cause segregation distortion through meiosis.
Transcriptomic and enzymological evidence for plastid peptidoglycan synthesis in the gymnosperm Picea abies
Yayoi Sugita, Amanda J. Dowson, Ichiro Kajisa, Katsuaki Takechi, Yilan E, Jingzhi Zhao, Jiaqi Wang, Xiaofei Lin, Laura Diaz-Saez, Adrian J. Lloyd, Christopher G. Dowson, Hiroyoshi Takano
It is understood that a cyanobacterium was the progenitor of plastids and that the biosynthesis of cell wall peptidoglycan was lost during chloroplast evolution. However, accumulated data, especially from the moss Physcomitrium patens, suggest that peptidoglycan remains essential for plastid division in some land plants. A fundamental set of peptidoglycan biosynthesis (Mur) genes has been identified in the genomes of these land plants, while many angiosperms no longer encode some core Mur genes, including a bifunctional penicillin-binding protein (PBP). Ten incomplete Mur genes were previously identified in the genome of the gymnosperm Picea abies but these could be pseudogenes or encode proteins that have been repurposed. For instance, mutant albino maize and Arabidopsis seedlings possess a defective UDP-N-acetylmuramoyl-l-alanyl-d-glutamate--2,6-diaminopimelate ligase (MurE), an intact MurE ligase being essential for peptidoglycan synthesis. In this study, we isolated a full set of cDNAs for peptidoglycan biosynthesis from P. abies. GFP fusion proteins with either P. abies (Pa)MurE or PaPBP were detected in chloroplasts. Cross-species complementation assays with PaMurE in Arabidopsis albino MurE mutants and Physcomitrium MurE chloroplast division mutants showed that the gymnosperm MurE completely rescued both mutant phenotypes. Enzymatic assay of recombinant PaMurE proteins revealed they catalyze the same reaction performed by their bacterial MurE homologs. Moreover, the expression of the PaPbp cDNA partially rescued the giant chloroplast phenotype in the moss Pbp knockout line. These results are consistent with the operation of a functional Mur gene set in the Norway spruce genome.
Update of general guidelines for statistically sound and risk-based surveys of plant pests
European Food Safety Authority (EFSA), Elena Lázaro, Stephen Parnell, Antonio Vicent Civera, Martijn Schenk, Jose Cortiñas Abrahantes, Juan Navas-Cortes, Hans-Hermann Thulke, Francesco Pecori, Joshua Koh, Jan Schans, Marc Aerts, Gabriele Zancanaro, Sybren Vos, Tomasz Kaluski
At the request of the European Commission, EFSA prepared the general guidelines for surveys of plant pests, describing the legal, international and scientific context in which the surveys are designed, the basic principles implemented for surveillance of quarantine pests and introducing the concepts needed for the design of statistically sound and risk-based surveys. Three types of specific surveys are addressed: detection surveys for substantiation of pest freedom, delimiting surveys to determine the boundaries of a potential infested zone, and monitoring surveys for prevalence estimation when measuring the effectiveness of eradication measures or for the confirmation of a low pest prevalence area. For each type of survey, the survey parameters are introduced and their interactions analysed showing the importance of the assumptions that are taken for each one of them:
1) The aims of the survey are defined as achieving a certain level of confidence of detecting a given pest prevalence (design prevalence), this reflects the trade-off between the acceptable level of the risk and availability of resources that determine the strength of the evidence to support the conclusion of the survey;
2) The target population is described by its structure and size, including the risk factors; and
3) The method sensitivity is defined as the combination of the sampling effectiveness and the diagnostic sensitivity for each inspection unit. EFSA's RiPEST and RiBESS+ tools1 are introduced for calculating the sample size using the survey parameters as input values for a statistically sound and risk-based survey design. The mathematical principles behind the tools are in line with the International Standards for Phytosanitary Measures. The survey design is flexible and can be tailored to each pest and specific situation in the Member States. Once the survey is implemented following this approach, the conclusions allow surveys to be compared across time and space, contributing to the harmonisation of surveillance activities across the EU Member States.
Bayesian inference of reproduction number from epidemiological and genetic data using particle MCMC
Alicia Gill, Jere Koskela, Xavier Didelot, Richard G Everitt
Inference of the reproduction number through time is of vital importance during an epidemic outbreak. Typically, epidemiologists tackle this using observed prevalence or incidence data. However, prevalence and incidence data alone are often noisy or partial. Models can also have identifiability issues with determining whether a large amount of a small epidemic or a small amount of a large epidemic has been observed. Sequencing data however are becoming more abundant, so approaches which can incorporate genetic data are an active area of research. We propose using particle MCMC methods to infer the time-varying reproduction number from a combination of prevalence data reported at a set of discrete times and a dated phylogeny reconstructed from sequences. We validate our approach on simulated epidemics with a variety of scenarios. We then apply the method to real datasets of HIV-1 in North Carolina, USA and tuberculosis in Buenos Aires, Argentina. The models and algorithms are implemented in an open source R package called EpiSky which is available at https://github.com/alicia-gill/EpiSkyLink opens in a new window.
Journal of the Royal Statistical Society Series C (Applied Statistics), December 2025
The Emergence of a CRISPR-Cas Revolution in Ecology: Applications, Challenges, and an Ecologist's Overview of the Toolbox
Amadeus Plewnia, Brandon D. Hoenig, Stefan Lötters, Christopher Heine, Jesse Erens, Philipp Böning, Gary D. Bending, Henrik Krehenwinkel, Molly Ann Williams
CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeats—CRISPR-associated nucleases) systems allow researchers to detect, capture, and even alter parts of an organism's genome. However, while the use of CRISPR-Cas has revolutionised many fields in the life sciences, its full potential remains underutilised in ecology and biodiversity research. Here we outline the emerging applications of CRISPR-Cas in ecological contexts, focusing on three main areas: nucleic acid detection, CRISPR-enhanced sequencing, and genome editing. CRISPR-based nucleic acid detection of environmental DNA samples is already reshaping species monitoring, providing highly sensitive and non-invasive tools for both scientists and the public alike, with reduced costs and minimal experience required. Further, CRISPR-enhanced sequencing, including Cas-mediated target enrichment, enables efficient recovery of ecologically relevant loci and supports diverse applications such as amplification-free metagenomics. Finally, while genome editing on wild species remains largely theoretical in ecology, these tools are already being used in controlled settings to study adaptation and resilience in the face of ongoing global stressors. Together, the applications of CRISPR-Cas are paving the way for more affordable, accessible, and impactful applications for species conservation, and promise to improve our ability to tackle the ongoing global biodiversity crisis.