Biology subjects

Kaul, V.

Publications and source records attributed to Kaul, V..

4 recordsLinked to original sources

bioRxiv2024

Minimal-invasive 3D laser printing of microimplants in organismo

Multi-photon 3D laser printing has gathered much attention in recent years as a means of manufacturing biocompatible scaffolds that can modify and guide cellular behavior in vitro. However, in vivo tissue engineering efforts have been limited so far to the implantation of beforehand 3D printed biocompatible scaffolds and in vivo bioprinting of tissue constructs from bioinks containing cells, biomolecules, and printable hydrogel formulations. Thus, a comprehensive 3D laser printing platform for in vivo and in situ manufacturing of microimplants raised from synthetic polymer-based inks is currently missing. Here we present a platform for minimal-invasive manufacturing of microimplants directly in the organism by one-photon photopolymerization and multi-photon 3D laser printing. Employing a commercially available elastomeric ink giving rise to biocompatible synthetic polymer-based microimplants, we demonstrate first applicational examples of biological responses to in situ printed microimplants in the teleost fish Oryzias latipes and in embryos of the fruit fly Drosophila melanogaster. This provides a framework for future studies addressing the suitability of inks for in vivo 3D manufacturing. Our platform bears great potential for the direct engineering of the intricate microarchitectures in a variety of tissues in model organisms and beyond.

bioengineering↗

bioRxiv2023

Divergent evolutionary strategies preempt tissue collision in fly gastrulation

Metazoan development proceeds through a series of morphogenetic events that sculpt body plans and organ structures. In the early embryonic stages, morphogenetic processes involving growth and deformation occur concurrently. Forces generated in one tissue can thus increase mechanical stress in the neighboring tissue, potentially disrupting spatial patterning, morphological robustness, and consequently decreasing organismal fitness. How organisms evolved mechanisms to reduce or release inter-tissue stresses remains poorly understood. Here we combined phylogenetic survey across a whole insect order (Diptera), quantitative live imaging, and functional mechanical perturbation to investigate the evolution of mechanical stress management during epithelial expansions in the gastrulating fly embryos. We find that two distinct cellular mechanisms exist in Diptera to prevent the accumulation of compressive stress that can arise when the expanding head and trunk tissues collide. In Cyclorrhapha, a monophyletic dipteran subgroup including the fruit fly Drosophila melanogaster, the head-trunk boundary undergoes active out-of-plane deformation to form a transient epithelial fold, called the cephalic furrow (CF), which acts as a mechanical sink to preempt head-trunk collision. Genetic or optogenetic elimination of the CF leads to tissue buckling, yielding deleterious effects of axial distortion that likely results from unmitigated release of compressive stress. Non-cyclorrhaphan flies, by contrast, lack CF formation and instead display widespread out-of-plane division in the head, which shortens the duration of its expansion and reduces surface area increase. Reorienting head mitosis in Drosophila from in-plane to out-of-plane partially suppresses the need for epithelial out-of-plane deformation, suggesting that out-of-plane division can act as an alternative mechanical sink to prevent tissue collision. Our data suggest that programs of mechanical stress management can emerge abruptly under selective pressure of inter-tissue mechanical conflict in early embryonic development.

developmental biology↗

bioRxiv2021

In vivo identification and validation of novel potential predictors for human cardiovascular diseases

Genetics crucially contributes to cardiovascular diseases (CVDs), the global leading cause of death. Since the majority of CVDs can be prevented by early intervention there is a high demand for predictive markers. While genome wide association studies (GWAS) correlate genes and CVDs after diagnosis and provide a valuable resource for such markers, preferentially those with previously known or suspected function are addressed further. To tackle the unaddressed blind spot of understudied genes, we particularly focused on the validation of heart GWAS candidates with little or no apparent connection to cardiac function. Building on the high conservation of basic heart function and underlying genetics from fish to human we combined CRISPR/Cas9 genome editing of the orthologs of human GWAS candidates in isogenic medaka with automated high-throughput heart rate analysis. Our functional analyses of understudied human candidates uncovered a prominent fraction of heart rate associated genes from adult human patients displaying a heart rate effect in embryonic medaka already in the injected generation. Following this pipeline, we identified 16 GWAS candidates with potential diagnostic and predictive power for human CVDs.

genetics↗

bioRxiv2020

Tissue-specific transcriptome profiling of the Arabidopsis thaliana inflorescence stem reveals local cellular signatures.

Genome-wide gene expression maps with a high spatial resolution have substantially accelerated molecular plant science. However, the number of characterized tissues and growth stages is still small because of the limited accessibility of most tissues for protoplast isolation. Here, we provide gene expression profiles of the mature inflorescence stem of Arabidopsis thaliana covering a comprehensive set of distinct tissues. By combining fluorescence-activated nucleus sorting and laser-capture microdissection with next generation RNA sequencing, we characterize transcriptomes of xylem vessels, fibers, the proximal and the distal cambium, phloem, phloem cap, pith, starch sheath, and epidermis cells. Our analyses classify more than 15,000 genes as being differentially expressed among different stem tissues and reveal known and novel tissue-specific cellular signatures. By determining transcription factor binding regions enriched in promoter regions of differentially expressed genes, we furthermore provide candidates for tissue-specific transcriptional regulators. Our datasets predict expression profiles of an exceptional amount of genes and allow generating hypotheses toward the spatial organization of physiological processes. Moreover, we demonstrate that information on gene expression in a broad range of mature plant tissues can be established with high spatial resolution by nuclear mRNA profiling. One sentence summaryA genome-wide high-resolution gene expression map of the Arabidopsis inflorescence stem is established.

plant biology↗