Publications by authors named "Nikolaos Doumpas"

The monitoring of contaminants in fish species is pivotal for fishes' health and reproduction, as well as for human health. In the specific work, three major categories of contaminants, pesticides, pharmaceuticals, and macro and trace elements, were investigated in two major fish species, and , collected from Thermaikos Gulf, in Greece. To achieve this goal, three analytical methods using LC-MS/MS, GC-MS/MS, and ICP-MS were developed, validated, and applied to the collected fish samples.

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During kidney development, reciprocal signaling between the epithelium and the mesenchyme coordinates nephrogenesis with branching morphogenesis of the collecting ducts. The mechanism that positions the renal vesicles, and thus the nephrons, relative to the branching ureteric buds has remained elusive. By combining computational modeling and experiments, we show that geometric effects concentrate the key regulator, WNT9b, at the junctions between parent and daughter branches where renal vesicles emerge, even when uniformly expressed in the ureteric epithelium.

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Here, we present a protocol for collecting high-spatiotemporal-resolution datasets of undisturbed mouse embryonic epithelial rudiments using light-sheet fluorescence microscopy. We describe steps for rudiment dissection, clearing, and embedding for cleared and live imaging. We then detail procedures for light-sheet imaging followed by image processing and morphometric analysis.

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Trace elements have the potential to bioaccumulate in marine organisms and to biomagnify towards the upper levels of marine trophic webs, resulting in a range of negative effects on organisms. Elasmobranchs are highly susceptible to bioaccumulation of trace metals, while their consumption by humans is increasing worldwide. Therefore, it is important to monitor the trace metal content in the edible tissues of elasmobranchs.

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Mouse embryonic stem cells (mESCs) can be maintained in vitro in defined N2B27 medium supplemented with two chemical inhibitors for GSK3 and MEK (2i) and the cytokine leukemia inhibitory factor (LIF), which act synergistically to promote self-renewal and pluripotency. Here, we find that genetic deletion of the four genes encoding the TCF/LEF transcription factors confers mESCs with the ability to self-renew in N2B27 medium alone. TCF/LEF quadruple knockout (qKO) mESCs display dysregulation of several genes, including Aire, Dnmt3l, and IcosL, located adjacent to each other within a topologically associated domain (TAD).

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We lack a holistic understanding of the genetic programs orchestrating embryonic colon morphogenesis and governing damage response in the adult. A window into these programs is the transcriptomes of the epithelial and mesenchymal cell populations in the colon. Performing unbiased single-cell transcriptomic analyses of the developing mouse colon at different embryonic stages (embryonic day 14.

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In the Mediterranean Sea, where biological invasions constitute a serious threat, the combination of citizen science and social networks amplified the power of proper field studies, recording species that would have otherwise presumably passed unnoticed. Based on data collected on several Facebook groups, we hereby first report the presence of five fish taxa (Kyphosus sp., Heniochus intermedius, Pomacanthus imperator, Pomacanthus maculosus and Abudefduf sp.

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BCL9 and PYGO are β-catenin cofactors that enhance the transcription of Wnt target genes. They have been proposed as therapeutic targets to diminish Wnt signaling output in intestinal malignancies. Here we find that, in colorectal cancer cells and in developing mouse forelimbs, BCL9 proteins sustain the action of β-catenin in a largely PYGO-independent manner.

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During canonical Wnt signalling, the activity of nuclear β-catenin is largely mediated by the TCF/LEF family of transcription factors. To challenge this view, we used the CRISPR/Cas9 genome editing approach to generate HEK 293T cell clones lacking all four TCF/LEF genes. By performing unbiased whole transcriptome sequencing analysis, we found that a subset of β-catenin transcriptional targets did not require TCF/LEF factors for their regulation.

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TOR complex 1 (TORC1) is a potent anabolic regulator of cellular growth and metabolism. When cells have sufficient amino acids, TORC1 is active due to its lysosomal localization mediated via the Rag GTPases. Upon amino acid removal, the Rag GTPases release TORC1, causing it to become cytoplasmic and inactive.

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Background: Wnt6 is an evolutionarily ancient member of the Wnt family. In Drosophila, Wnt6 loss-of-function animals have not yet been reported, hence information about fly Wnt6 function is lacking. In wing discs, Wnt6 is expressed at the dorsal/ventral boundary in a pattern similar to that of wingless, an important regulator of wing size.

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The molecular mechanisms regulating tissue size represent an unsolved puzzle in developmental biology. One signalling pathway controlling growth of the Drosophila wing is Dpp. Dpp promotes growth by repression of the transcription factor Brk.

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