Biology subjects

Elewa, A.

Publications and source records attributed to Elewa, A..

7 recordsLinked to original sources

bioRxiv2026

The 3D Ultrastructure of C. elegans Gut Granules

We identify an endoderm-restricted organelle in published volume electron microscopy datasets of C. elegans embryos. The organelle consists of a tubular ring surrounding a membrane-bound compartment harboring a prominent dense particle and exhibits a basal polarity and size concordant with canonical gut granules. This finding offers ultrastructural detail to recent evidence that gut granules are bi-lobed organelles with two distinct compartments.

cell biology↗

bioRxiv2025

Modeling human phenotypes in the nematode C. elegans during an undergraduate developmental biology course

Caenorhabditis elegans is a widely used model organism in biomedical research due to its genetic tractability, short life cycle, and conservation of many developmental processes with humans. In this study, undergraduate students conducted nine independent experiments during a Developmental Biology course to model human phenotypes using C. elegans. Each group selected a human phenotype of interest, identified a gene associated with the phenotype, and then determined the orthologous or homologous gene in C. elegans. By obtaining mutants and designing phenotypic assays, students investigated the extent to which the worm models could recapitulate aspects of the human condition. This collective work highlights both the potential and limitations of C. elegans as a model for human phenotypic variation and disease and demonstrates the value of undergraduate inquiry as a catalyst for scientific engagement and research-based learning.

scientific communication and education↗

bioRxiv2022

Sequencing and chromosome-scale assembly of the giant Pleurodeles waltl genome

The Iberian ribbed newt (Pleurodeles waltl) constitutes a central model for probing the basis of vertebrate regeneration. Here, we present the sequencing and chromosome-scale assembly of the 20.3Gb P. waltl genome, which exhibits the highest level of contiguity and completeness among giant genome assemblies. We uncover that DNA transposable elements are the major contributors to its expansion, with hAT transposons comprising a large portion of repeats. Several hATs are actively transcribed and differentially expressed during adult P. waltl limb regeneration, along with domesticated hAT transposons of the ZBED transcription factor family. Despite its size, syntenic relationships are conserved. As an example, we show the high degree of conservation of the regeneration-associated Tig1 locus with several neighbouring genes. Together, the P. waltl genome provides a fundamental resource for the study of regenerative, developmental and evolutionary principles.

developmental biology↗

bioRxiv2022

Telomerase-independent maintenance of telomere length in a vertebrate

Telomere shortening places a key limitation on cell proliferation1. In all vertebrates explored to date, this limitation is overcome by telomerase-dependent telomere extension. Failure to maintain telomere length results in premature ageing and functional impairments in highly replicative cell populations as telomeres erode2. Alternative lengthening of telomeres (ALT), a telomerase-independent mechanism, compensates for telomere loss in a subset of human cancer cell lines 2. Here, we demonstrate that the highly regenerative newt Pleurodeles waltl lacks telomerase activity, contains telomeres distinct from all known vertebrates in both sequence and structure, and deploys ALT for physiological telomere maintenance. This constitutes the first report of telomerase-independent resolution of the end-replication problem at the whole-organism level within Chordata. One-Sentence SummaryP. waltl telomere biology is distinct amongst vertebrates and uses ALT at the whole-organism level.

molecular biology↗

bioRxiv2021

Tig1 regulates proximo-distal identity during salamander limb regeneration

Salamander limb regeneration is an accurate process which gives rise exclusively to the missing structures, irrespective of the amputation level. This suggests that cells in the stump have an awareness of their spatial location, a property termed positional identity. Little is known about how positional identity is encoded, in salamanders or other biological systems. Through single-cell RNAseq analysis, we identified Tig1/Rarres1 as a potential determinant of proximal identity. Tig1 encodes a conserved cell surface molecule, is regulated by retinoic acid and exhibits a graded expression along the proximo-distal axis of the limb. Its overexpression leads to regeneration defects in the distal elements and elicits proximal displacement of blastema cells, while its neutralisation blocks proximo-distal cell surface interactions. Critically, Tig1 reprogrammes distal cells to a proximal identity, upregulating Prod1 and inhibiting Hoxa13 and distal transcriptional networks. Thus, Tig1 is a central cell surface determinant of proximal identity in the salamander limb.

developmental biology↗

bioRxiv2020

Does the Inertia of a Cell Depend Upon its Information-Content?

A time dilation factor is derived from information entropy via the holographic principle. By imagining the embryonic cell as a hologram, time dilation during embryogenesis is predicted from the entropy of active genetic information and shown to be consistent with observed lengths of cell duration. The connection between entropy and cell duration as well as the corollary of increase in cellular mass with the reduction in information entropy are discussed. This preprint is the second in a series exploring the value of Developmental Spacetime as a framework for falsifiable predictions about the universe.

developmental biology↗

bioRxiv2020

A Waddington Epigenetic Landscape for the C. elegans embryo

Waddingtons Epigenetic Landscape provides a visual model for both robust and adaptable development. Generating and exploring a Waddington epigenetic landscape for the early C. elegans embryo suggests that the key shapers of the landscape are genes that lie at the nexus between stress response and behavior and include genes that are regulated by transgenerational neuronal small RNAs. Curiously, several genes shape the early landscape of one lineage and then pattern, differentiate or are enriched in another lineage. Additionally, paralogs with similar expression profiles contribute differently to shaping the modeled landscape. This work suggests that robust embryonic development is initialized by differential deployment of redundant genes and by transgenerational cues that configure the epigenetic landscape to adapt to a changing world.

developmental biology↗