Biology subjects

Engels, T.

Publications and source records attributed to Engels, T..

6 recordsLinked to original sources

bioRxiv2025

Diptera flight diversity is shaped by aerodynamic constraints, scaling, and evolutionary trade-offs

Flight has been a key innovation in insect evolution, yet the selective and mechanistic pressures shaping their flight motor systems remain poorly understood. Here, we present a comprehensive comparative analysis of flight in Diptera (true flies), integrating morphology, wingbeat kinematics, and aerodynamics within a phylogenetic framework. We quantified morphology in 133 species spanning the Dipteran phylogenetic and size range, and for a subset of 46 species we combined high-speed stereoscopic videography with computational fluid dynamics (CFD) to characterize wingbeat kinematics and aerodynamic performance, respectively. Our results reveal that morphology is strongly structured by phylogeny, whereas wingbeat kinematics are broadly conserved across Diptera, reflecting dominant aerodynamic constraints. Two early-diverged lineages, Culicomorpha (mosquitoes and midges) and Tipulomorpha (crane flies), exhibit strikingly divergent kinematics and aerodynamics, suggesting lineage-specific selective pressures. Combining these data with our scaling analyses suggests that tiny Diptera are primarily constrained by aerodynamic force production, and maintain weight support through relatively larger wings and increased wingbeat frequencies. In contrast, as Diptera increase in size, hovering flight becomes progressively constrained by power availability, resulting in markedly elevated relative flight-muscle mass among the largest species. Mosquitoes and midges represent an extreme case, exhibiting a pronounced aerodynamic-acoustic trade-off with disproportionately large flight musculature and increased aerodynamic and acoustic power, consistent with selection favoring acoustic signaling during in-swarm mating. By integrating comparative morphology, kinematics, and aerodynamics across a major insect radiation, our study uncovers the interplay between physical scaling laws, aerodynamic constraints, and ecological pressures in shaping the evolution of animal flight. These findings provide a mechanistic framework for understanding how complex locomotor systems diversify under multiple selection pressures.

evolutionary biology↗

bioRxiv2025

Olfactory performance explains duality of antennal architectural designs in Lepidoptera

Male attraction by females through sex pheromones is widespread among Lepidoptera, and antennae are key olfactory organs during male orientation. Broadly speaking, two designs of antennae coexist in Lepidoptera: complex (pectinate) or stick-like (filiform) ones. Pectinate antennae have attracted attention because of their multiscale geometry, assumed to outperform filiform. Yet, the filiform design is by far more common. We compare the olfactory performance of the two designs using modeling, particle image velocimetry on 3D-printed scaled-up models, and computational simulations. In terms of absolute odor capture, pectinate antennae perform better at nearly all flying speeds. However, when considering drag, filiform designs are more energy-efficient than pectinate ones at low flight speeds, while the reverse holds at high speeds. This is due to the differential scaling of drag and molecule capture with flight speed. According to our results, small and slow moths would bear filiform antennae whereas big and fast moths would have pectinate ones, which is the general trend observed in Nature. We discuss exceptions to this general pattern and how species could evolve from one design to the other by investigating the influence of the antennal structural elements.

physiology↗

bioRxiv2025

Muscle power output reflects elevated viscosity in the propulsion system of flying miniature wasps

Air viscosity compromises aerodynamic lift production in the smallest flying insects, leading to increased flight costs. Miniature insects thus utilize both lift and drag for weight support but the exact energetic costs of wing flapping at low Reynolds number are widely unexplored. We estimated flight power in the miniature wasp Eretmocerus mundus. Wing kinematics was three-dimensionally reconstructed using high-speed video and computational fluid dynamics simulated air flows, aerodynamic forces and moments. We found an asymmetrical crescent-shaped wingtip trajectory with the upstroke posterior to the downstroke path. This fore-aft distance increases with increasing horizontal flight velocity, maintaining the wings backwards rowing motion needed for drag-based propulsion. Although the wings lift-to-drag ratio is below unity, lift is the predominant force responsible for weight support and forward thrust. Elevated drag leads to mass-specific mechanical power output of 118{+/-}9.0 Wkg-1 flight muscle, which exceeds most power estimates reported for other insects, birds and bats. The elevated energetic costs for flight may have fostered the development of bristled wings in miniature insects. Altogether, our study of wingbeat control and flight costs in a miniature insect extends the scope of flight mechanisms to the smallest flying animals revealing limits of miniaturization during the evolution of flight.

biophysics↗

bioRxiv2024

cMPL-Based Purification and Depletion of Human Hematopoietic Stem Cells: Implications for Pre-Transplant Conditioning

The transplantation of gene-modified autologous hematopoietic stem and progenitor cells (HSPCs) offers a promising therapeutic approach for hematological and immunological disorders. However, this strategy is often limited by the toxicities associated with traditional conditioning regimens. Antibody-based conditioning strategies targeting cKIT and CD45 antigens have shown potential in mitigating these toxicities, but their long-term safety and efficacy in clinical settings require further validation. In this study, we investigate the thrombopoietin (TPO) receptor, cMPL, as a novel target for conditioning protocols. We demonstrate that high surface expression of cMPL is a hallmark feature of long-term repopulating hematopoietic stem cells (LT-HSCs) within the adult human CD34+ HSPC subset. Targeting the cMPL receptor facilitates the separation of human LT-HSCs from mature progenitors, a delineation not achievable with cKIT. Leveraging this finding, we developed a cMPL-targeting immunotoxin, demonstrating its ability to selectively deplete host cMPLhigh LT-HSCs with a favorable safety profile and rapid clearance within 24 hours post-infusion in rhesus macaques. These findings present significant potential to advance our understanding of human hematopoiesis and enhance the therapeutic outcomes of ex vivo autologous HSPC gene therapies. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=154 SRC="FIGDIR/small/581887v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@10b265aorg.highwire.dtl.DTLVardef@102ec94org.highwire.dtl.DTLVardef@fa269dorg.highwire.dtl.DTLVardef@fd2583_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO C_FIG

cell biology↗

bioRxiv2021

A novel flight style allowing the smallest featherwing beetles to excel

Flight speed generally correlates positively with animal body size1. Surprisingly, miniature featherwing beetles can fly at speeds and accelerations of insects three times as large2. We show here that this performance results from a previously unknown type of wing motion. Our experiment combines three-dimensional reconstructions of morphology and kinematics in one of the smallest insects, Paratuposa placentis (body length 395 m). The flapping bristled wing follows a pronounced figure-eight loop that consists of subperpendicular up and down strokes followed by claps at stroke reversals, above and below the body. Computational analyses suggest a functional decomposition of the flapping cycle in two power half strokes producing a large upward force and two down-dragging recovery half strokes. In contrast to heavier membranous wings, the motion of bristled wings of the same size requires little inertial power. Muscle mechanical power requirements thus remain positive throughout the wing beat cycle, making elastic energy storage obsolete. This novel flight style evolved during miniaturization may compensate for costs associated with air viscosity and helps explain how extremely small insects preserved superb aerial performance during miniaturization. Incorporating this flight style in artificial flappers is a challenge for designers of micro aerial vehicles.

zoology↗

bioRxiv2021

Activity of Plasmodium vivax promoter elements in Plasmodium knowlesi, and a centromere-containing plasmid that expresses NanoLuc throughout the parasite life cycle

BackgroundPlasmodium knowlesi is now the major cause of human malaria in Malaysia, complicating malaria control efforts that must attend to the elimination of multiple Plasmodium species. Recent advances in the cultivation of P. knowlesi erythrocytic-stage parasites in vitro, transformation with exogenous DNA, and infection of mosquitoes with gametocytes from culture have opened up studies of this pathogen without the need for resource-intensive and costly non-human primate (NHP) models. For further understanding and development of methods for parasite transformation in malaria research, this study examined the activity of various trans-species transcriptional control sequences and the influence of Plasmodium vivax centromeric (pvcen) repeats in plasmid-transfected P. knowlesi parasites. MethodsIn vitro cultivated P. knowlesi parasites were transfected with plasmid constructs that incorporated P. vivax or Plasmodium falciparum 5 UTRs driving the expression of bioluminescence markers (firefly luciferase or Nanoluc). Promoter activities were assessed by bioluminescence, and parasites transformed with human resistant allele dihydrofolate reductase-expressing plasmids were selected using antifolates. The stability of transformants carrying pvcen-stabilized episomes was assessed by bioluminescence over a complete parasite life cycle through a rhesus macaque monkey, mosquitoes, and a second rhesus monkey. ResultsLuciferase expression assessments show that certain P. vivax promoter regions, not functional in the more evolutionarily-distant P. falciparum, can drive transgene expression in P. knowlesi. Further, pvcen repeats may improve the stability of episomal plasmids in P. knowlesi and support detection of NanoLuc-expressing elements over the full parasite life cycle from rhesus macaque monkeys to Anopheles dirus mosquitoes and back again to monkeys. In assays of drug responses to chloroquine, G418 and WR9910, antimalarial half-inhibitory concentration (IC50) values of blood stages measured by NanoLuc activity proved comparable to IC50 values measured by the standard SYBR Green method. ConclusionAll three P. vivax promoters tested in this study functioned in P. knowlesi whereas two of the three were inactive in P. falciparum. NanoLuc-expressing, centromere-stabilized plasmids may support high-throughput screenings of P. knowlesi for new antimalarial agents, including compounds that can block the development of mosquito- and/or liver-stage parasites.

microbiology↗