126 research outputs found
mRNA analysis of single living cells
Analysis of specific gene expression in single living cells may become an important technique for cell biology. So far, no method has been available to detect mRNA in living cells without killing or destroying them. We have developed here a novel method to examine gene expression of living cells using an atomic force microscope (AFM). AFM tip was inserted into living cells to extract mRNAs. The obtained mRNAs were analyzed with RT-PCR, nested PCR, and quantitative PCR. This method enabled us to examine time-dependent gene expression of single living cells without serious damage to the cells
mRNA detection of individual cells with the single cell nanoprobe method compared with in situ hybridization
<p>Abstract</p> <p>Background</p> <p>The localization of specific mRNA generates cell polarity by controlling the translation sites of specific proteins. Although most of these events depend on differences in gene expression, no method is available to examine time dependent gene expression of individual living cells. <it>In situ </it>hybridization (ISH) is a powerful and useful method for detecting the localization of mRNAs, but it does not allow a time dependent analysis of mRNA expression in single living cells because the cells have to be fixed for mRNA detection. To overcome these issues, the extraction of biomolecules such as mRNAs, proteins, and lipids from living cells should be performed without severe damage to the cells. In previous studies, we have reported a single cell nanoprobe (SCN) method to examine gene expression of individual living cells using atomic force microscopy (AFM) without killing the cells.</p> <p>Results</p> <p>In order to evaluate the SCN method, we compared the SCN method with <it>in situ </it>hybridization (ISH). First, we examined spatial β-actin mRNA expression in single living cells with the SCN method, and then the same cells were subjected to ISH for β-actin mRNA. In the SCN method, quantity of β-actin mRNA were analysed by quantitative PCR, and in ISH we used intensity of ISH as a parameter of concentration of β-actin mRNA. We showed that intensity of ISH is higher; quantity of β-actin mRNA detected by the SCN method increased more.</p> <p>Conclusion</p> <p>In this study, we compare the SCN method with the ISH. We examined β-actin mRNA expression in single cells using both methods. We picked up β-actin mRNA from several loci of a single living cell using an AFM nanoprobe, and identical cells were subjected to ISH. The results showed a good correlation between the SCN method and ISH. The SCN method is suitable and reliable to examine mRNAs at medium or higher expression level.</p
Feasibility study on ground-state cooling and single-phonon readout of trapped electrons using hybrid quantum systems
Qubits of long coherence time and fast quantum operations are long-sought
objectives towards the realization of high-fidelity quantum operations and
their applications to the quantum technologies. An electron levitated in a
vacuum by a Paul trap is expected to be a good candidate, for its light mass
and hence the high secular frequency which allows for the faster gate
operations than those in trapped ions. Controlling the motional state of the
trapped electron is a crucial issue, for it mediates an interaction between
electron spins, intrinsic qubits embedded in electrons, and its decoherence
results in degraded fidelity of two-qubit gates. In addition, an efficient
readout of the motional state is important, regarding the possibility of
detecting spin state by using it. Despite of such an importance, how to achieve
the motional ground state and how to efficiently detect it are not reported so
far. Here we propose methods addressing these issues by utilizing hybrid
quantum systems involving electron-superconducting circuit and electron-ion
coupled systems and analyze the feasibility of our schemes. In both systems, we
show that the ground-state cooling and the single-phonon readout of the
motional state of the trapped electron are possible. Our work shed light on the
way to precisely control the motional states of the trapped electrons, that
provides an interesting playground for the development of quantum technologies.Comment: 9 pages, 5figures, 2 table
Compact atom source using fiber-based pulsed laser ablation
We designed, demonstrated, and characterized an atom source based on
fiber-based pulsed laser ablation. By using commercially available miniature
lens system for focusing nanosecond pulsed laser of up to 225~J delivered
through a multimode fiber of 105~m core, we successfully ablate a
SrTiO target and generate a jet of neutral strontium atoms, though our
method can be applied to other transparent ablation targets containing
materials under concern. Our device endures 6\,000 cycles of pulse delivery and
irradiation without noticeable damage on the fiber facets and lenses. The
generated strontium beam is characterized with spectroscopic method and is
revealed to exhibit the transverse temperature of 800~K and longitudinal
velocity of 2\,300~m/s, which are typical of pulsed-laser-ablation-based atom
source. The number of atoms generated by a single ablation pulse is estimated
to be . Our device provides a compact, cryo-compatible
fiber-pigtailed atom source with minimized device footprints and reduced
complexity of vacuum systems to further promote the developments of cold-atom
experiments. It may also find interesting applications in atomic and molecular
sciences.Comment: 4 pages, 3 figure
All-microwave manipulation of superconducting qubits with a fixed-frequency transmon coupler
All-microwave control of fixed-frequency superconducting quantum computing
circuits is advantageous for minimizing the noise channels and wiring costs.
Here we introduce a swap interaction between two data transmons assisted by the
third-order nonlinearity of a coupler transmon under a microwave drive. We
model the interaction analytically and numerically and use it to implement an
all-microwave controlled-Z gate. The gate based on the coupler-assisted swap
transition maintains high drive efficiency and small residual interaction over
a wide range of detuning between the data transmons.Comment: 12 pages, 8 figure
Interaction between Pheromone and Its Receptor of the Fission Yeast Schizosaccharomyces pombe Examined by a Force Spectroscopy Study
Interaction between P-factor, a peptide pheromone composed of 23 amino acid residues, and its pheromone receptor, Mam2, on the cell surface of the fission yeast Schizosaccharomyces pombe was examined by an atomic force microscope (AFM). An AFM tip was modified with P-factor derivatives to perform force curve measurements. The specific interaction force between P-factor and Mam2 was calculated to be around 120 pN at a probe speed of 1.74 μm/s. When the AFM tip was modified with truncated P-factor derivative lacking C-terminal Leu, the specific interaction between the tip and the cell surface was not observed. These results were also confirmed with an assay system using a green fluorescent protein (GFP) reporter gene to monitor the activation level of signal transduction following the interaction of Mam2 with P-factor
Radiation Hybrid Maps of Medaka Chromosomes LG 12, 17, and 22
The Medaka is an excellent genetic system for studies of vertebrate development and disease and environmental and evolutionary biology studies. To facilitate the mapping of markers or the cloning of affected genes in Medaka mutants identified by forward-genetic screens, we have established a panel of whole-genome radiation hybrids (RHs) and RH maps for three Medaka chromosomes. RH mapping is useful, since markers to be mapped need not be polymorphic and one can establish the order of markers that are difficult to resolve by genetic mapping owing to low genetic recombination rates. RHs were generated by fusing the irradiated donor, OLF-136 Medaka cell line, with the host B78 mouse melanoma cells. Of 290 initial RH clones, we selected 93 on the basis of high retention of fragments of the Medaka genome to establish a panel that allows genotyping in the 96-well format. RH maps for linkage groups 12, 17, and 22 were generated using 159 markers. The average retention for the three chromosomes was 19% and the average break point frequency was ∼33 kb/cR. We estimate the potential resolution of the RH panel to be ∼186 kb, which is high enough for integrating RH data with bacterial artificial chromosome clones. Thus, this first RH panel will be a useful tool for mapping mutated genes in Medaka
Fast parametric two-qubit gates with suppressed residual interaction using the second-order nonlinearity of a cubic transmon
We demonstrate fast two-qubit gates using a parity-violated superconducting qubit consisting of a capacitively shunted asymmetric Josephson-junction loop under a finite magnetic flux bias. The second-order nonlinearity manifesting in the qubit enables the interaction with a neighboring single-junction transmon qubit via first-order interqubit sideband transitions with Rabi frequencies up to 30 MHz. Simultaneously, the unwanted static longitudinal (ZZ) interaction is eliminated with ac Stark shifts induced by a continuous microwave drive near resonant to the sideband transitions. The average fidelities of the two-qubit gates are evaluated with randomized benchmarking as 0.971, 0.958, and 0.962 for CZ, iswap, and swap gates, respectively
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