Biology subjects

Kerner, P.

Publications and source records attributed to Kerner, P..

6 recordsLinked to original sources

bioRxiv2025

Multifaceted conserved functions of Notch during post-embryonic neurogenesis in the annelid Platynereis

Notch signaling is an evolutionarily conserved pathway known to orchestrate neurogenesis by regulating the transition of progenitor cells to differentiated neurons and glia, as well as by directing neurite outgrowth and axon guidance in many species. Although extensively studied in vertebrates and ecdysozoans, the role of Notch in spiralians (including mollusks, annelids or flatworms) remains largely unexplored, limiting our understanding of its conserved functions across bilaterians. In this study, we focus on the segmented annelid Platynereis dumerilii, a model organism in neurobiology and regeneration, to investigate Notch signaling functions during post-embryonic developmental processes. We show that Notch pathway components are expressed in neurogenic territories during both posterior elongation and regeneration, two processes requiring sustained neurogenesis. Through chemical inhibitions of the pathway and RNA-seq profiling, we demonstrate that Notch signaling regulates neural progenitor specification, differentiation, and overall neurogenic balance in the regenerating and elongating posterior part. Moreover, disruption of Notch activity leads to severe defects in pygidial and central nervous system organization, including abnormal axon guidance and impaired neurite outgrowth. Altogether, our results support the hypothesis that Notch has multifaceted conserved functions in neurogenesis across bilaterians, shedding light on the ancestral functions of this critical pathway.

developmental biology↗

bioRxiv2024

Biochar Modulates Wheat Root Metabolome and Rhizosphere Microbiome in a Feedstock-dependent Manner

BackgroundBiochar is a multifunctional soil conditioner capable of enhancing soil health and plant productivity, but the underlying mechanisms remain elusive. Here we tackled this question using wheat as a model plant and through the lens of the rhizosphere, a vital soil-plant interface continuum. We systematically examined the effects of four types of biochar (corn stover, cattle manure, pine sawdust, or wheat straw) applied at two rates (0.25% or 2.5%, w/w). ResultsEmploying untargeted metabolomics and 16S rRNA gene sequencing, we revealed both common and unique modulating effects of the tested biochar treatments on wheat root metabolites and rhizosphere microbiome structure and functioning. Biochar modulated numerous metabolic pathways in wheat roots, where amino acid metabolism was the most common one, leading to cascade effects on the dynamics of a wide range of secondary metabolites, including many plant signaling molecules (e.g., flavonoid compounds, brassinosteroids) that are known to be involved in plant-microbe interactions. All biochar treatments increased rhizosphere microbial diversity, altered community composition, enhanced microbial interactions, and resulted in functional changes. Increased Burkholderiales (denitrifying bacteria) abundance and decreased Thermoplasmata (archaeal methanogens) abundance could explain biochars widely reported effects on nitrous oxide and methane mitigation, respectively. Biochar enhanced positive correlations among microbes and network complexity, particularly modularity, suggesting local adaptation through mutualism and/or synergism and the formation of modules of functionally interrelated taxa. A large number of diverse keystone taxa from both dominant and non-dominant phyla emerged after biochar treatments, including those known to be involved in methane, nitrogen, and sulfur cycling. Besides common alterations, treatment-specific alterations also occurred, and biochar type (i.e., feedstock choice) exerted greater influence than application rate. Wheat biochar applied at a 0.25% rate showed the strongest and distinct modulating effects, resulting in orchestrated changes in both root metabolites and rhizosphere microbiome, especially those relevant to plant-microbe interactions and likely beneficial to the host plant (e.g., upregulated biosynthesis of zeatin and down-regulated limonene degradation). ConclusionsOur work contributes to a mechanistic understanding of how biochar modulates the soil-plant continuum and provides new insights into the potential of top-down rhizosphere microbiome engineering through biochar-based reprogramming of root-microbe interactions.

microbiology↗

bioRxiv2023

Microbial Responses to Biochar Soil Amendment and Influential Factors: A Three-level Meta-analysis

Biochar is a multifunctional soil conditioner capable of enhancing soil health and crop production while reducing greenhouse gas emissions. Understanding how soil microbes respond to biochar amendment is a vital step towards precision biochar application. Here, we synthesized 3899 observations of 24 microbial responses from 61 primary studies, applied a three-level mixed-effects model to estimate biochar effects, and evaluated the importance of biochar characteristics (feedstock, pyrolysis temperature), soil properties (pH, C:N, cation exchange capacity, bulk or rhizosphere), and treatment protocols (application rate, fertilization, duration, field or laboratory). Biochar significantly boosts microbial abundance (microbial biomass carbon > CFU), nitrite reductase gene (nirS), the activity of C- and N-cycling enzymes (dehydrogenase > cellulase > urease > invertase), and potential nitrification rate. Biochar characteristics, soil properties, and treatment protocols strongly determine the direction and extent of microbial response changes. Feedstock, pyrolysis temperature, application rate, and soil pH are important predictors most frequently included in the final models. Our study highlights the promise of purpose-driven biochar production and application such that biochar production parameters can be tuned to elicit the desired microbial responses and application protocols could be optimized to invoke multiple benefits. It also underlines current knowledge gaps and future research needs. SynopsisMeta-analysis reveals overall effect sizes of soil microbial responses to biochar amendment and the most influential factors, highlighting the potential of purpose-driven precision biochar towards sustainable agriculture.

ecology↗

bioRxiv2022

Differential effects of carbon nanotube and graphene on the tomato rhizosphere microbiome

Application of carbonaceous nanomaterials (CNMs) to the soil-plant system can affect plant physiology, with positive results ranging from enhanced seed germination and root system development to improved stress tolerance. The underlying mechanisms are not fully understood. Plant rhizosphere microbiomes at the soil-root interface are strongly influenced by the host plant and play a key role in the plant hosts development and health. Yet few studies have characterized changes in plant rhizosphere microbiomes following applications of CNMs to the soil-plant system. Here we investigated the effects of multi-walled carbon nanotube (CNT) and graphene on microbial communities in the ectorhizosphere of tomato plants versus surrounding bulk soil. Pot experiments were conducted where tomato plants were exposed to CNT or graphene at 200 mg/kg soil for four weeks. Ectorhizosphere and bulk soils were then collected and analyzed for physicochemical properties and microbiome structure and function. While graphene had a limited impact on the tomato rhizosphere microbiome, CNT significantly increased microbial alpha diversity, induced greater divergence of beta diversity, enhanced microbial interactions, and potentially impacted community functions such as aromatic compound degradation, antioxidant synthesis, and redox cofactor biosynthesis. Furthermore, CNT induced stronger and/or unique microbiome alterations in the tomato rhizosphere compared to bulk soil. Our findings reveal the differential modulating effects of two widely-used CNMs on plant rhizosphere microbiomes and highlight an imminent need to understand complex plant root-microbe interplays in the CNM-impacted rhizosphere. These results have implication for realizing the full potential of phytoapplication of CNMs toward improved and sustainable plant production.

microbiology↗

bioRxiv2020

DNA methylation during development and regeneration of the annelid Platynereis dumerilii

BackgroundMethylation of cytosines in DNA (5mC methylation) is a major epigenetic modification that modulates gene expression and is important for embryonic development and cell reprogramming in vertebrates. In mammals, 5mC methylation in promoter regions is linked to transcriptional repression. Transcription regulation by 5mC methylation notably involves the Nucleosome Remodeling and Deacetylase complex (NuRD complex) which bridges DNA methylation and histone modifications. Less is known about roles and mechanisms of 5mC methylation in non-vertebrate animals. In this paper, we study 5mC methylation in the marine annelid worm Platynereis dumerilii, an emerging evolutionary and developmental biology model capable of regenerating the posterior part of its body upon amputation. The regenerated region includes both differentiated structures and a growth zone consisting of stem cells required for the continuous growth of the worm. ResultsUsing in silico and experimental approaches, we show that P. dumerilii displays a high level of DNA methylation comparable to that of mammalian somatic cells. 5mC methylation in P. dumerilii is dynamic along the life cycle of the animal and markedly decreases at the transition between larval to post-larval stages. We identify a full repertoire of mainly singlecopy genes encoding the machinery associated to 5mC methylation or members of the NuRD complex in P. dumerilii and show, through phylogenetic analyses, that this repertoire is close to the one inferred for the last common ancestor of bilaterians. These genes are dynamically expressed during P. dumerilii development, growth and regeneration. Treatment with the DNA hypomethylating agent Decitabine, impairs P. dumerilii larval development and regeneration, and has long-term effects on post-regenerative growth by affecting the functionality of stem cells of the growth zone. ConclusionsOur data indicate high-level of 5mC methylation in the annelid P. dumerilii, highlighting that this feature is not specific to vertebrates in the bilaterian clade. Analysis of DNA methylation levels and machinery gene expression during development and regeneration, as well as the use of a chemical inhibitor of DNA methylation, suggest an involvement of 5mC methylation in P. dumerilii development, regeneration and stem cell-based post-regenerative growth. We also present data indicating that P. dumerilii constitutes a promising model to study biological roles and mechanisms of DNA methylation in non-vertebrate bilaterians and to provide new knowledge about evolution of the functions of this key epigenetic modification in bilaterian animals.

developmental biology↗

bioRxiv2019

Globins and hemogenic cells in the marine Annelid Platynereis dumerilii shed new light on blood evolution in Bilaterians

BackgroundHow vascular systems and their respiratory pigments evolved is still debated. While many animals present a vascular system, hemoglobin exists as a blood pigment only in a few groups (Vertebrates, Annelids, a few Arthropod and Mollusk species). Hemoglobins are formed of globin sub-units, belonging to multigene families, in various multimeric assemblages. It was so far unclear whether hemoglobin families from different Bilaterian groups had a common origin. ResultsTo unravel globin evolution in Bilaterians, we studied the marine Annelid Platynereis dumerilii, a species with a slow evolving genome. Platynereis exhibits a closed vascular system filled with extracellular hemoglobin. Platynereis genome and transcriptomes reveal a family of 19 globins, nine of which are predicted to be extracellular. Extracellular globins are produced by specialized cells lining the vessels of the segmental appendages of the worm, serving as gills, and thus likely participate in the assembly of the giant hexagonal bilayer hemoglobin of the worm. Extracellular globin mRNAs are absent in smaller juvenile, accumulate considerably in growing and more active worms and peak in swarming adults, as the need for O2 culminates. Next, we conducted a Metazoan-wide phylogenetic analysis of globins using data from complete genomes. We establish that five globin genes (stem globins) were present in the last common ancestor of Bilaterians. Based on these results, we propose a new nomenclature of globins, with five clades. All five ancestral stem-globin clades are retained in some Spiralians, while some clades disappeared early in Deuterostome and Ecdysozoan evolution. All known Bilaterian blood globin families are grouped in a single clade (clade I) together with intracellular globins of Bilaterians devoid of red blood. ConclusionsWe uncover a complex "pre-blood" evolution of globins, with an early gene radiation in ancestral Bilaterians. Circulating hemoglobins in various bilaterian groups evolved convergently, presumably in correlation with animal size and activity. However, all hemoglobins derive from a clade I globin, or cytoglobin, probably involved in intracellular O2 transit and regulation (clade I). The Annelid Platynereis is remarkable in having a large family of extracellular blood globins, while retaining all clades of ancestral Bilaterian globins.

evolutionary biology↗