Through various pathways of cell death, degradation, and regulated extrusion, partial or complete genomes of various origins (e.g., host cells, fetal cells, and infiltrating viruses and microbes) are ...continuously shed into human body fluids in the form of segmented cell-free DNA (cfDNA) molecules. While the genetic complexity of total cfDNA is vast, the development of progressively efficient extraction, high-throughput sequencing, characterization via bioinformatics procedures, and detection have resulted in increasingly accurate partitioning and profiling of cfDNA subtypes. Not surprisingly, cfDNA analysis is emerging as a powerful clinical tool in many branches of medicine. In addition, the low invasiveness of longitudinal cfDNA sampling provides unprecedented access to study temporal genomic changes in a variety of contexts. However, the genetic diversity of cfDNA is also a great source of ambiguity and poses significant experimental and analytical challenges. For example, the cfDNA population in the bloodstream is heterogeneous and also fluctuates dynamically, differs between individuals, and exhibits numerous overlapping features despite often originating from different sources and processes. Therefore, a deeper understanding of the determining variables that impact the properties of cfDNA is crucial, however, thus far, is largely lacking. In this work we review recent and historical research on active vs. passive release mechanisms and estimate the significance and extent of their contribution to the composition of cfDNA.
The 2022 outbreak of the monkeypox virus already involves, by April 2023, 110 countries with 86,956 confirmed cases and 119 deaths. Understanding an emerging disease on a molecular level is essential ...to study infection processes and eventually guide drug discovery at an early stage. To support this, we provide the so far most comprehensive structural proteome of the monkeypox virus, which includes 210 structural models, each computed with three state-of-the-art structure prediction methods. Instead of building on a single-genome sequence, we generated our models from a consensus of 3,713 high-quality genome sequences sampled from patients within 1 year of the outbreak. Therefore, we present an average structural proteome of the currently isolated viruses, including mutational analyses with a special focus on drug-binding sites. Continuing dynamic mutation monitoring within the structural proteome presented here is essential to timely predict possible physiological changes in the evolving virus.
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•The distribution of circulating cell-free DNA coverage over the respective reference genome is highly non-uniform.•Retrotransposable elements and non-telomeric satellite DNA are ...consistently overrepresented in human plasma and bovine serum.•Telomeric satellite DNA is underrepresented.•DNA from retrotransposable elements and non-telomeric satellite DNA is potentially actively secreted from cells, most likely via exosomes.•Sepsis patients have elevated fractions of DNA from retrotransposable elements.
Circulating cell-free DNAs (cfDNAs) are DNA fragments which can be isolated from mammalian blood serum or plasma. In order to gain deeper insight into their origin(s), we have characterized the composition of human and cattle cfDNA via large-scale analyses of high-throughput sequencing data. We observed significant differences between the composition of cfDNA in serum/plasma and the corresponding DNA sequence composition of the human genome. Retrotransposable elements and non-telomeric satellite DNA were particularly overrepresented in the cfDNA population, while telomeric satellite DNA was underrepresented. This was consistently observed for human plasma, bovine serum and for the supernatant of human cancer cell cultures. Our results suggest that reverse transcription of retrotransposable elements and secondary-structure formation during the replication of satellite DNA are contributing to the composition of the cfDNA molecules in the mammalian blood stream. We believe that our work is an important step towards the understanding of the biogenesis of cfDNAs and thus may also facilitate the future exploitation of their diagnostic potential.
•Assay is based on host-response, NOT on pathogen detection•Assay detects sepsis 2–3 days before the first clinical signs•Assay is robust (DNA-based)•Assay uses serum or plasma without further ...isolation/purification steps
We have identified 24 molecular markers, based on circulating nucleic acids (CNA) originating from the human genome, which in combination can be used in a quantitative real-time PCR (qPCR) assay to identify the presence of human sepsis, starting two to three days before the first clinical signs develop and including patients who meet the SEPSIS-3 criteria. The accuracy was more than 87 % inside of the same patient cohort for which the markers were developed and up to 81 % in blind studies of patient cohorts which were not included in the marker development. As our markers are host-based, they can be used to capture bacterial as well as fungal sepsis, unlike the current PCR-based tests, which require species-specific primer sets for each organism causing human sepsis. Our assay directly uses an aliquot of cell-free blood as the substrate for the PCR reaction, thus allowing to obtain the diagnostic results in three to four hours after the collection of the blood samples.
Accurate 3D reconstruction of neurons is vital for applications linking anatomy and physiology. Reconstructions are typically created using Neurolucida after biocytin histology (BH). An alternative ...inexpensive and fast method is to use freeware such as Neuromantic to reconstruct from fluorescence imaging (FI) stacks acquired using 2-photon laser-scanning microscopy during physiological recording. We compare these two methods with respect to morphometry, cell classification, and multicompartmental modeling in the NEURON simulation environment. Quantitative morphological analysis of the same cells reconstructed using both methods reveals that whilst biocytin reconstructions facilitate tracing of more distal collaterals, both methods are comparable in representing the overall morphology: automated clustering of reconstructions from both methods successfully separates neocortical basket cells from pyramidal cells but not BH from FI reconstructions. BH reconstructions suffer more from tissue shrinkage and compression artifacts than FI reconstructions do. FI reconstructions, on the other hand, consistently have larger process diameters. Consequently, significant differences in NEURON modeling of excitatory post-synaptic potential (EPSP) forward propagation are seen between the two methods, with FI reconstructions exhibiting smaller depolarizations. Simulated action potential backpropagation (bAP), however, is indistinguishable between reconstructions obtained with the two methods. In our hands, BH reconstructions are necessary for NEURON modeling and detailed morphological tracing, and thus remain state of the art, although they are more labor intensive, more expensive, and suffer from a higher failure rate due to the occasional poor outcome of histological processing. However, for a subset of anatomical applications such as cell type identification, FI reconstructions are superior, because of indistinguishable classification performance with greater ease of use, essentially 100% success rate, and lower cost.
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