Biology subjects

Nozaki, S.

Publications and source records attributed to Nozaki, S..

4 recordsLinked to original sources

bioRxiv2026

Engineering developmental transitions during human neurulation through modular integration of multimodal spatial cues

Reconstituting organ development in vitro requires reproducing dynamic developmental transitions rather than only terminal tissue structures. Here, we developed MoSAIC (Modular Spatial Assembly and Integration of Cues), a modular platform that decomposes complex culture operations and subsequently integrates them to reconstruct multimodal mechano-chemical spatial cues. Using human induced pluripotent stem cells, MoSAIC enabled independent control of tissue geometry, extracellular matrix localization, physical boundaries, and morphogen gradients, while also permitting defined mechanical and chemical perturbations during development. Their integration guided a continuous ectodermal sheet through neural induction, tissue bending, and bifurcation into neural and epidermal tissues, followed by formation of a polarized neural tube structure. Spatially controlled morphogen exposure further established dorsoventral patterning, while the resulting tissue exhibited posterior neural tube identity. Using the developed model recapitulating the transition of human neurulation, MoSAIC further enables non-genetic perturbation of mechanical and chemical cues to interrogate the mechanisms governing neural tube closure.

bioengineering↗

bioRxiv2026

PhAGE Enables One-Step Genome Integration of Large DNA Fragments in Escherichia coli

Escherichia coli is a well-established model organism in molecular biology and biotechnology. Despite its long history as a laboratory workhorse, the efficient single-step chromosomal integration of large DNA fragments remains a challenge. Currently known methods are either simple but have limitations on insert size, or flexible but laborious requiring plasmid construction or multi-step procedures. Here, we present PhAGE (Phage-Assisted Genome Engineering), which enables the integration of [~]20 kb DNA fragments into E. coli genome within a single day. PhAGE method uses in vitro packaging of recombinant DNA into bacteriophage capsids, followed by general transduction to introduce pre-assembled DNA with flanking homology arms into recipient cells. This approach allows efficient and landing pad-free integration of large constructs into the target loci. We demonstrate its usefulness through rapid integration of multi-gene operons. PhAGE resolves the long-standing trade-off between simplicity and insert size in E. coli genome engineering, accelerating strain construction across a wide range of applications, from biosynthetic pathway engineering to genome-scale design.

synthetic biology↗

bioRxiv2022

Rapid and accurate assembly of large DNA assisted by in vitro packaging of bacteriophage

Development of DNA assembly methods made it possible to construct large DNA. However, achieving the large DNA assembly easily, accurately, and at low cost remains a challenge. This study shows that DNA assembled only by annealing of overlapping single-stranded DNA ends, which are generated by exonuclease treatment, without ligation can be packaged in phage particles and can also be transduced into bacterial cells. Based on this, I developed a simple method to construct long DNA of about 40 - 50 kb from multiple PCR fragments using the bacteriophage in vitro packaging system. This method, named iPac (in vitro Packaging-assisted DNA assembly), allowed accurate and rapid construction of large plasmids and phage genomes. This simple method will accelerate research in molecular and synthetic biology, including the construction of gene circuits or the engineering of metabolic pathways. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=98 SRC="FIGDIR/small/502418v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@13aa8f6org.highwire.dtl.DTLVardef@2aea9aorg.highwire.dtl.DTLVardef@19054c2org.highwire.dtl.DTLVardef@acb76a_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2018

Exonuclease III (XthA) enforces in vivo DNA cloning of Escherichia coli to create cohesive ends

Escherichia coli has an ability to assemble DNA fragments with homologous overlapping sequences of 15-40 bp at each end. Several modified protocols have already been reported to improve this simple and useful DNA-cloning technology. However, the molecular mechanism by which E. coli accomplishes such cloning is still unknown. In this study, we provide evidence that the in vivo cloning of E. coli is independent of both RecA and RecET recombinase, but is dependent on XthA, a 3 to 5 exonuclease. Here, in vivo cloning of E. coli by XthA is referred to as iVEC (in vivo E. coli cloning). Next, we show that the iVEC activity is reduced by deletion of the C-terminal domain of DNA polymerase I (PolA). Collectively, these results suggest the following mechanism of iVEC. First, XthA resects the 3' ends of linear DNA fragments that are introduced into E. coli cells, resulting in exposure of the single-stranded 5' overhangs. Then, the complementary single-stranded DNA ends hybridize each other, and gaps are filled by DNA polymerase I. Elucidation of the iVEC mechanism at the molecular level would further advance the development of in vivo DNA-cloning technology. Already we have successfully demonstrated multiple-fragment assembly of up to seven fragments in combination with an effortless transformation procedure using a modified host strain for iVEC.\n\nImportanceCloning of a DNA fragment into a vector is one of the fundamental techniques in recombinant DNA technology. Recently, in vitro recombination of DNA fragments effectively joins multiple DNA fragments in place of the canonical method. Interestingly, E. coli can take up linear double-stranded vectors, insert DNA fragments and assemble them in vivo. The in vivo cloning have realized a high level of usability comparable to that by in vitro recombination reaction, since now it is only necessary to introduce PCR products into E. coli for the in vivo cloning. However, the mechanism of in vivo cloning is highly controversial. Here we clarified the fundamental mechanism underlying in vivo cloning of E. coli and also constructed an E. coli strain that was optimized for in vivo cloning.

bioengineering↗