Nanoplastics can cause severe malformations in chicken embryos. To improve our understanding of the toxicity of nanoplastics to embryos, we have studied their biodistribution in living chicken... Show moreNanoplastics can cause severe malformations in chicken embryos. To improve our understanding of the toxicity of nanoplastics to embryos, we have studied their biodistribution in living chicken embryos. We injected the embryos in the vitelline vein at stages 18–19. We injected polystyrene nanoparticles (PS-NPs) tagged with europium- or fluorescence. Their biodistribution was tracked using inductively-coupled plasma mass spectrometry on tissue lysates, paraffin histology, and vibratome sections analysed by machine learning algorithms. PS-NPs were found at high levels in the heart, liver and kidneys. Furthermore, PS-NPs crossed the endocardium of the heart at sites of epithelial-mesenchymal transformation; they also crossed the liver endothelium. Finally, we detected PS-NPs in the allantoic fluid, consistent with their being excreted by the kidneys. Our study shows the power of the chicken embryo model for analysing the biodistribution of nanoplastics in embryos. Such experiments are difficult or impossible in mammalian embryos. These findings are a major advance in our understanding of the biodistribution and tissue-specific accumulation of PS-NPs in developing animals. Show less
This thesis focuses on important life history traits and their trade-offs using two hexapod models. Particularly, the trade-off between immune defense and embryonic developmental speed is a central... Show moreThis thesis focuses on important life history traits and their trade-offs using two hexapod models. Particularly, the trade-off between immune defense and embryonic developmental speed is a central theme of this study. In short, I study the details of immune defenses during embryonic development of basal hexapods in Chapter 2, the trade-off with developmental speed in Chapter 3, and the genetic basis of developmental speed in Chapter 4, using selection lines of the red flour beetle Tribolium castaneum. I demonstrate that 1) springtail eggs do show an immune response, despite absence of a serosa that provides immune protection to insect eggs; 2) a strong trade-off is present between developmental speed and fecundity in the selection lines of the beetle T. castaneum; and 3) a life-history allele of large effect shortens developmental time in this wild insect population. I suggest that such alleles of large effect play a crucial role when insects have to adapt their developmental speed to current climate change. Show less
Cheng, S.; Jacobs, C.G.; Mogollón Pérez, E.A.; Chen, D.; Sanden, J.T. van de; Bretscher, K.M.; ... ; Zee, M. van der 2023
Developmental time is a key life-history trait with large effects on Darwinian fitness. In many insects, developmental time is currently under strong selection to minimize ecological mismatches in... Show moreDevelopmental time is a key life-history trait with large effects on Darwinian fitness. In many insects, developmental time is currently under strong selection to minimize ecological mismatches in seasonal timing induced by climate change. The genetic basis of responses to such selection, however, is poorly understood. To address this problem, we set up a long-term evolve-and-resequence experiment in the beetle Tribolium castaneum and selected replicate, outbred populations for fast or slow embryonic development. The response to this selection was substantial and embryonic developmental timing of the selection lines started to diverge during dorsal closure. Pooled whole-genome resequencing, gene expression analysis and an RNAi screen pinpoint a 222 bp deletion containing binding sites for Broad and Tramtrack upstream of the ecdysone degrading enzyme Cyp18a1 as a main target of selection. Using CRISPR/Cas9 to reconstruct this allele in the homogenous genetic background of a laboratory strain, we unravel how this single deletion advances the embryonic ecdysone peak inducing dorsal closure and show that this allele accelerates larval development but causes a trade-off with fecundity. Our study uncovers a life-history allele of large effect and reveals the evolvability of developmental time in a natural insect population. Show less
Wang, M.; Rücklin, M.; Poelmann, R.E.; Mooij, C.L. de; Fokkema, M.; Lamers, G.E.M.; ... ; Richardson, M.K. 2023
Nanomaterials are widespread in the human environment as pollutants, and are being actively developed for use in human medicine. We have investigated how the size and dose of polystyrene... Show moreNanomaterials are widespread in the human environment as pollutants, and are being actively developed for use in human medicine. We have investigated how the size and dose of polystyrene nanoparticles affects malformations in chicken embryos, and have characterized the mechanisms by which they interfere with normal development. We find that nanoplastics can cross the embryonic gut wall. When injected into the vitelline vein, nanoplastics become distributed in the circulation to multiple organs. We find that the exposure of embryos to polystyrene nanoparticles produces malformations that are far more serious and extensive than has been previously reported. These malformations include major congenital heart defects that impair cardiac function. We show that the mechanism of toxicity is the selective binding of polystyrene nanoplastics nanoparticles to neural crest cells, leading to the death and impaired migration of those cells. Consistent with our new model, most of the malformations seen in this study are in organs that depend for their normal development on neural crest cells. These results are a matter of concern given the large and growing burden of nanoplastics in the environment. Our findings suggest that nanoplastics may pose a health risk to the developing embryo. Show less
Objective. To evaluate the efficacy and safety of apremilast, an oral phosphodiesterase 4 inhibitor, in patients with active ankylosing spondylitis (AS).Methods. This phase III, multicenter, double... Show moreObjective. To evaluate the efficacy and safety of apremilast, an oral phosphodiesterase 4 inhibitor, in patients with active ankylosing spondylitis (AS).Methods. This phase III, multicenter, double-blind, placebo-controlled study (ClinicalTrials.gov: NCT01583374) randomized patients with active AS (1:1:1) to placebo, apremilast 20 mg twice daily, or apremilast 30 mg twice daily for 24 weeks, followed by a long-term extension phase (up to 5 yrs). The primary endpoint was Assessment of the Spondyloarthritis international Society 20 (ASAS20) response at Week 16. The effect of treatment on radiographic outcomes after 104 weeks was assessed using the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS).Results. In total, 490 patients with active AS were randomized in the study (placebo: n = 164; apremilast 20 mg twice daily: n = 163; apremilast 30 mg twice daily: n = 163). The primary endpoint of ASAS20 response at Week 16 was not met (placebo: 37%; apremilast 20 mg twice daily: 35%; apremilast 30 mg twice daily: 33%; P = 0.44 vs placebo). At Week 104, mean (SD) changes from baseline in mSASSS were 0.83 (3.6), 0.98 (2.2), and 0.57 (1.9) in patients initially randomized to placebo, apremilast 20 mg twice daily, and apremilast 30 mg twice daily, respectively. The most frequently reported adverse events through Week 104 were diarrhea, nasopharyngitis, upper respiratory infection, and nausea.Conclusion. No clinical benefit was observed with apremilast treatment in patients with active AS. The safety and tolerability of apremilast were consistent with its known profile. Show less
Background The western flower thrips,Frankliniella occidentalis(Pergande), is a globally invasive pest and plant virus vector on a wide array of food, fiber, and ornamental crops. The underlying... Show moreBackground The western flower thrips,Frankliniella occidentalis(Pergande), is a globally invasive pest and plant virus vector on a wide array of food, fiber, and ornamental crops. The underlying genetic mechanisms of the processes governing thrips pest and vector biology, feeding behaviors, ecology, and insecticide resistance are largely unknown. To address this gap, we present theF. occidentalisdraft genome assembly and official gene set.Results We report on the first genome sequence for any member of the insect order Thysanoptera. Benchmarking Universal Single-Copy Ortholog (BUSCO) assessments of the genome assembly (size = 415.8 Mb, scaffold N50 = 948.9 kb) revealed a relatively complete and well-annotated assembly in comparison to other insect genomes. The genome is unusually GC-rich (50%) compared to other insect genomes to date. The official gene set (OGS v1.0) contains 16,859 genes, of which similar to 10% were manually verified and corrected by our consortium. We focused on manual annotation, phylogenetic, and expression evidence analyses for gene sets centered on primary themes in the life histories and activities of plant-colonizing insects. Highlights include the following: (1) divergent clades and large expansions in genes associated with environmental sensing (chemosensory receptors) and detoxification (CYP4, CYP6, and CCE enzymes) of substances encountered in agricultural environments; (2) a comprehensive set of salivary gland genes supported by enriched expression; (3) apparent absence of members of the IMD innate immune defense pathway; and (4) developmental- and sex-specific expression analyses of genes associated with progression from larvae to adulthood through neometaboly, a distinct form of maturation differing from either incomplete or complete metamorphosis in the Insecta.Conclusions Analysis of theF. occidentalisgenome offers insights into the polyphagous behavior of this insect pest that finds, colonizes, and survives on a widely diverse array of plants. The genomic resources presented here enable a more complete analysis of insect evolution and biology, providing a missing taxon for contemporary insect genomics-based analyses. Our study also offers a genomic benchmark for molecular and evolutionary investigations of other Thysanoptera species. Show less
Doublecortin-like (DCL) is a microtubule-binding protein crucial for neuroblastoma (NB) cell proliferation. We have investigated whether the anti-proliferative effect of DCL knockdown is linked to... Show moreDoublecortin-like (DCL) is a microtubule-binding protein crucial for neuroblastoma (NB) cell proliferation. We have investigated whether the anti-proliferative effect of DCL knockdown is linked to reduced mitochondrial activity. We found a delay in tumor development after DCL knockdown in vivo in doxycycline-inducible NB tumor xenografts. To understand the mechanisms underlying this tumor growth retardation we performed a series of in vitro experiments in NB cell lines. DCL colocalizes with mitochondria, interacts with the mitochondrial outer membrane protein OMP25/ SYNJ2BP and DCL knockdown results in decreased expression of genes involved in oxidative phosphorylation. Moreover, DCL knockdown decreases cytochrome c oxidase activity and ATP synthesis. We identified the C-terminal Serine/Proline-rich domain and the second microtubule-binding area as crucial DCL domains for the regulation of cytochrome c oxidase activity and ATP synthesis. Furthermore, DCL knockdown causes a significant reduction in the proliferation rate of NB cells under an energetic challenge induced by low glucose availability. Together with our previous studies, our results corroborate DCL as a key player in NB tumor growth in which DCL controls not only mitotic spindle formation and the stabilization of the microtubule cytoskeleton, but also regulates mitochondrial activity and energy availability, which makes DCL a promising molecular target for NB therapy. Show less
