Biology subjects

Schoborg, T.

Publications and source records attributed to Schoborg, T..

7 recordsLinked to original sources

bioRxiv2025

The microcephaly protein Abnormal Spindle has an essential role in symmetrically dividing neural precursors to promote brain growth and development

Neurogenesis must be coordinated in time and space to ensure proper neural development. Defects in this process can lead to a variety of brain malformations that affect tissue size and architecture. Here we examine the spatiotemporal requirements of the Abnormal Spindle (Asp) protein and its human ortholog Abnormal Spindle-Like, Microcephaly Associated (ASPM) in a fly model of human microcephaly (MCPH). By utilizing the fly optic lobe, whose neurogenic program parallels that of mammals, and the genetic tools available in this organism, we uncover the progenitor cell types and critical neurogenesis window necessary for proper brain size and architecture. Asp has an essential function in symmetrically dividing neuroepithelial precursors, yet its expression in asymmetrically dividing neuroblasts alone is not sufficient for optic lobe development. Asp is highly expressed during both embryonic and larval neurogenesis stages, but embryonic expression is dispensable for making a properly sized adult brain. We also show that Asp/ASPMs interphase nuclear localization is not required for its ability to promote brain development. Expression of the human ASPM N-terminus can also significantly rescue fly brain defects, suggesting conserved mechanisms of function in brain growth control. These results support a model where Asp expression in symmetrically dividing precursors is required to generate a sufficient pool of progenitors prior to the cell fate switch to asymmetrically dividing neuroblasts in order to generate enough neuronal cells to make a properly sized brain.

developmental biology↗

bioRxiv2024

A Deep Learning Model for Accurate Segmentation of the Drosophila melanogaster Brain from Micro-CT Imaging

The use of microcomputed tomography (Micro-CT) for imaging biological samples has burgeoned in the past decade, due to increased access to scanning platforms, ease of operation, isotropic three-dimensional image information, and the ability to derive accurate quantitative data. However, manual data analysis of Micro-CT images can be laborious and time intensive. Deep learning offers the ability to streamline this process, but historically has included caveats--namely, the need for a large amount of training data, which is often limited in many Micro-CT studies. Here we show that accurate deep learning models can be trained using only 1-3 Micro-CT images of the adult Drosophila melanogaster brain using Dragonflys pre-trained neural networks and minimal user knowledge. We further demonstrate the power of our model by showing that it can accurately segment the brain across different tissue contrast stains, scanner models, and genotypes. Finally, we show how the model can assist in identifying morphological similarities and differences between mutants based on volumetric quantification, facilitating a rapid assessment of novel phenotypes. Our models are freely available and can be refined based on individual user needs. SummaryMicro-CT data can be automatically segmented and quantified using a deep learning model trained on as few as 3 samples, facilitating rapid comparison of developmental phenotypes.

developmental biology↗

bioRxiv2024

Computed Tomography of Polymeric Biomedical Implants from Bench to Bedside

Implanted biomedical devices require porosity to encourage tissue regeneration. However, characterizing porosity, which affects many functional device properties, is non-trivial. Computed tomography (CT) is a quick, versatile, and non-destructive way to gain 3D structural information. While optimization of CT for polymeric devices has been investigated at the bench on high-resolution micro-CT (CT) scanners, pre-clinical and clinical systems cannot be tuned the same way, given an overriding objective to minimize ionizing radiation exposure to living tissues. Therefore, in this study we tested feasibility of obtaining structural information in pre-clinical systems and CT under physiological conditions. The size of resolved features in porous structures is highly dependent on the resolution (voxel size) of the scan. Lower resolution underestimated porosity and overestimated pore size. With the homogeneous introduction of radiopaque nanoparticle contrast agent into both biopolymers and synthetic polymers, devices could be imaged in the hydrated state, even at high-resolution. Biopolymers had significant structural changes at the micro-scale post-hydration, including a mean increase of 130% in pore wall thickness that could potentially impact biological response. Through optimizing devices for medical imaging, CT has the potential to be a facile way to monitor devices from initial design stages through to clinical translation.

bioengineering↗

bioRxiv2023

Sex-Dependent Genetic Expression Signatures within Cocaine- and Sucrose-Seeking Ensembles in Mice

Maladaptive reward seeking is a hallmark of cocaine use disorder. To develop therapeutic targets, it is critical to understand the neurobiological changes specific to cocaine-seeking without altering the seeking of natural rewards, e.g., sucrose. The prefrontal cortex (PFC) and the nucleus accumbens core (NAcore) are known regions associated with cocaine- and sucrose-seeking ensembles, i.e., a sparse population of co-activated neurons. Within ensembles, transcriptomic alterations in the PFC and NAcore underlie the learning and persistence of cocaine- and sucrose-seeking behavior. However, transcriptomes exclusively driving cocaine seeking independent from sucrose seeking have not yet been defined using a within-subject approach. Using Ai14:cFos-TRAP2 transgenic mice in a dual cocaine and sucrose self-administration model, we fluorescently sorted (FACS) and characterized (RNAseq) the transcriptomes defining cocaine- and sucrose-seeking ensembles. We found reward- and region-specific transcriptomic changes that will help develop clinically relevant genetic approaches to decrease cocaine-seeking behavior without altering non-drug reward-based positive reinforcement.

neuroscience↗

bioRxiv2023

The neurodevelopmental transcriptome of the Drosophila melanogaster microcephaly gene abnormal spindle reveals a role for temporal transcription factors and the immune system in regulating brain size

The coordination of cellular behaviors during neurodevelopment is critical for determining the form, function, and size of the central nervous system. Mutations in the vertebrate Abnormal Spindle-Like, Microcephaly Associated (ASPM) gene and its Drosophila melanogaster ortholog abnormal spindle (asp) lead to microcephaly, a reduction in overall brain size whose etiology remains poorly defined. Here we provide the neurodevelopmental transcriptional landscape for a Drosophila model for autosomal recessive primary microcephaly (MCPH) and extend our findings into the functional realm in an attempt to identify the key cellular mechanisms responsible for Asp-dependent brain growth and development. We identify multiple transcriptomic signatures, including new patterns of co-expressed genes in the developing CNS. Defects in optic lobe neurogenesis were detected in larval brains through downregulation of temporal transcription factors (tTFs) and Notch signaling targets, which correlated with a significant reduction in brain size and total cell numbers during the neurogenic window of development. We also found inflammation as a hallmark of asp MCPH brains, detectable throughout every stage of CNS development, which also contributes to the brain size phenotype. Finally, we show that apoptosis is not a primary driver of the asp MCPH phenotype, further highlighting an intrinsic Asp-dependent neurogenesis promotion mechanism that is independent of cell death. Collectively, our results suggest that the etiology of asp MCPH is complex and that a comprehensive view of the cellular basis of the disorder requires an understanding of how multiple pathway inputs collectively determine the microcephaly phenotype. AUTHOR SUMMARYAutosomal recessive primary microcephaly (MCPH) is a neurodevelopmental disorder characterized by a reduction in brain size, intellect, and life span. Over 30 genes have been found mutated in human MCPH patients, with Abnormal Spindle-Like, Microcephaly Associated (ASPM) being the most common. Although the clinical aspects of the disorder are well-characterized, the underlying cellular and molecular mechanisms are not. The fruit fly, Drosophila melanogaster, has an ortholog of the ASPM gene named abnormal spindle (asp), and mutations also give rise to fruit flies with small brains. It had previously been suggested that mitotic spindle defects were responsible for the asp MCPH phenotype, preventing neural stem cells from dividing properly to generate the necessary number of neurons and glia in the brain. However, genetic studies in flies showed that this wasnt the case, suggesting that our knowledge of MCPH remains incomplete and must be revised. In this manuscript, we identified new pathways important for asp-dependent brain growth through transcriptional profiling. We found a number of key pathways disrupted in asp mutants, which have not been described previously. Using genetic tools in the fly, we tested a subset of these pathways to identify their contributions to the brain growth defects seen in asp mutants. Our results add to the growing number of pathways necessary for brain growth control, and provide a suitable foundation for follow-up genetic studies to assess MCPH.

developmental biology↗

bioRxiv2019

A Drosophila Insulator Interacting Protein Suppresses Enhancer-Blocking Function and Modulates Replication Timing

Insulators play important roles in genome structure and function in Drosophila and mammals. More than six different insulator proteins are required in Drosophila for normal genome function, whereas CTCF is the only identified protein contributing to insulator function in mammals. Interactions between a DNA binding insulator protein and its interacting partner proteins define the properties of each insulator site. The different roles of insulator protein partners in the Drosophila genome and how they confer functional specificity remain poorly understood. Functional analysis of insulator partner proteins in Drosophila is necessary to understand how genomes are compartmentalized and the roles that different insulators play in genome function. In Drosophila, the Suppressor of Hairy wing [Su(Hw)] insulator is targeted to the nuclear lamina, preferentially localizes at euchromatin/heterochromatin boundaries, and is associated with the Gypsy retrotransposon. The properties that the insulator confers to these sites rely on the ability of the Su(Hw) protein to bind the DNA at specific sites and interact with Mod(mdg4)-67.2 and CP190 partner proteins. HP1 and insulator partner protein 1 (HIPP1) is a recently identified partner of Su(Hw), but how HIPP1 contributes to the function of Su(Hw) insulators has not yet been elucidated. Here, we find that mutations in the HIPP1 crotonase-like domain have no impact on the function of Su(Hw) enhancer-blocking activity but do exhibit an impaired ability to repair double-strand breaks. Additionally, we find that the overexpression of each HIPP1 and Su(Hw) causes defects in cell proliferation by limiting the progression of DNA replication. We also find that HIPP1 overexpression suppresses the Su(Hw) insulator enhancer-blocking function.

molecular biology↗

bioRxiv2018

Micro computed tomography as an accessible imaging platform for exploring organism development and human disease modeling

Understanding how events at the molecular and cellular scales contribute to tissue form and function is key to uncovering mechanisms driving animal development, physiology and disease. Elucidating these mechanisms has been enhanced through the study of model organisms and the use of sophisticated genetic, biochemical and imaging tools. Here we present an optimized method for non-invasive imaging of Drosophila melanogaster at high resolution using micro computed tomography (-CT). Our method allows for rapid processing of intact animals at any developmental stage, provides precise quantitative assessment of tissue size and morphology, and permits analysis of inter-organ relationships. We then use the power of -CT imaging to model human diseases through the characterization of microcephaly in the fly. Our work demonstrates that -CT is a versatile and accessible tool that complements standard imaging techniques, capable of uncovering novel biological mechanisms that have remained undocumented due to limitations of current methods.

developmental biology↗