Biology subjects

Engels, M.

Publications and source records attributed to Engels, M..

3 recordsLinked to original sources

bioRxiv2026

Dissetangling the Vine: Phylogenomics and Historical Biogeography of Vanilla (Orchidaceae)

Renowned for its aromatic fruits and economic importance, the genus Vanilla poses longstanding taxonomic and phylogenetic challenges. Despite recent molecular studies, a comprehensive species tree is lacking, and the evolutionary processes and historical patterns shaping the genus remain poorly understood. We present a new, comprehensive phylogenomic framework for Vanilla, based on 349 low-copy nuclear genes and 76 plastid loci from the Angiosperms353 probe set, which we used to infer evolutionary relationships, assess cyto-nuclear and gene-species tree discordance, and thoroughly investigate its historical distribution and diversification. Sampling 43% of the genus, our framework resolves phylogenetic uncertainties, clarifies major clades, confirms prior hypotheses, and reveals novel placements, including V. planifolia and Vanilla subg. Gondwana. Discordances are primarily driven by incomplete lineage sorting, particularly in the vanillin-producing clade, with evidence of both ancient and recent hybridization, including a natural hybrid from the Yucatan Peninsula. Biogeographic analyses indicate a Guiana Shield origin ([~]30 Mya), Amazonia as a major diversification source, the Andes as a permeable barrier, and Central America as the main diversification sink. This study provides a robust evolutionary framework for Vanilla, supporting taxonomic revisions, comparative trait analyses, and a deeper understanding of the processes shaping this economically and biologically important orchid genus.

evolutionary biology↗

bioRxiv2023

Auditory confounds can drive online effects of transcranial ultrasonic stimulation in humans

Transcranial ultrasonic stimulation (TUS) is rapidly emerging as a promising non-invasive neuromodulation technique. TUS is already well-established in animal models, providing foundations to now optimize neuromodulatory efficacy for human applications. Across multiple studies, one promising protocol, pulsed at 1000 Hz, has consistently resulted in motor cortical inhibition in humans (Fomenko et al., 2020). At the same time, a parallel research line has highlighted the potentially confounding influence of peripheral auditory stimulation arising from TUS pulsing at audible frequencies. In this study, we disentangle direct neuromodulatory and indirect auditory contributions to motor inhibitory effects of TUS. To this end, we include tightly matched control conditions across four experiments, one preregistered, conducted independently at three institutions. We employed a combined transcranial ultrasonic and magnetic stimulation paradigm, where TMS-elicited motor-evoked potentials (MEPs) served as an index of corticospinal excitability. First, we replicated motor inhibitory effects of TUS but showed through both tight controls and manipulation of stimulation intensity, duration, and auditory masking conditions that this inhibition was driven by peripheral auditory stimulation, not direct neuromodulation. Further, we consider neuromodulation beyond driving overall excitation/inhibition and show preliminary evidence of how TUS might interact with ongoing neural dynamics instead. Primarily, this study highlights the substantial shortcomings in accounting for the auditory confound in prior TUS-TMS work where only a flip-over sham and no active control was used. The field must critically reevaluate previous findings given the demonstrated impact of peripheral confounds. Further, rigorous experimental design via (in)active control conditions is required to make substantiated claims in future TUS studies. Only when direct effects are disentangled from those driven by peripheral confounds can TUS fully realize its potential for research and clinical applications.

neuroscience↗

bioRxiv2021

Scent dog identification of SARS-CoV-2 infections, similar across different body fluids

BackgroundThe main strategy to contain the current SARS-CoV-2 pandemic remains to implement a comprehensive testing, tracing and quarantining strategy until vaccination of the population is adequate. MethodsTen dogs were trained to detect SARS-CoV-2 infections in beta-propiolactone inactivated saliva samples. The subsequent cognitive transfer performance for the recognition of non-inactivated samples were tested on saliva, urine, and sweat in a randomised, double-blind controlled study. ResultsDogs were tested on a total of 5242 randomised sample presentations. Dogs detected non-inactivated saliva samples with a diagnostic sensitivity of 84% and specificity of 95%. In a subsequent experiment to compare the scent recognition between the three non-inactivated body fluids, diagnostic sensitivity and specificity were 95% and 98% for urine, 91% and 94% for sweat, 82%, and 96% for saliva respectively. ConclusionsThe scent cognitive transfer performance between inactivated and non-inactivated samples as well as between different sample materials indicates that global, specific SARS-CoV-2-associated volatile compounds are released across different body secretions, independently from the patients symptoms. FundingThe project was funded as a special research project of the German Armed Forces. The funding source DZIF-Fasttrack 1.921 provided us with means for biosampling.

animal behavior and cognition↗