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"Paul Monnier"
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H19 lncRNA controls gene expression of the Imprinted Gene Network by recruiting MBD1
The H19 gene controls the expression of several genes within the Imprinted Gene Network (IGN), involved in growth control of the embryo. However, the underlying mechanisms of this control remain elusive. Here, we identified the methyl-CpG–binding domain protein 1 MBD1 as a physical and functional partner of the H19 long noncoding RNA (lncRNA). The H19 lncRNA–MBD1 complex is required for the control of five genes of the IGN. For three of these genes— Igf2 (insulin-like growth factor 2), Slc38a4 (solute carrier family 38 member 4), and Peg1 (paternally expressed gene 1)—both MBD1 and H3K9me3 binding were detected on their differentially methylated regions. The H19 lncRNA–MBD1 complex, through its interaction with histone lysine methyltransferases, therefore acts by bringing repressive histone marks on the differentially methylated regions of these three direct targets of the H19 gene. Our data suggest that, besides the differential DNA methylation found on the differentially methylated regions of imprinted genes, an additional fine tuning of the expressed allele is achieved by a modulation of the H3K9me3 marks, mediated by the association of the H19 lncRNA with chromatin-modifying complexes, such as MBD1. This results in a precise control of the level of expression of growth factors in the embryo.
Journal Article
Hybrid indium phosphide-on-silicon nanolaser diode
By exploiting one-dimensional photonic crystal nanocavities, an ultra-compact indium phosphide-on-silicon laser diode with low current threshold, high wall-plug efficiency and high integrability is demonstrated.
The most-awaited convergence of microelectronics and photonics promises to bring about a revolution for on-chip data communications and processing
1
. Among all the optoelectronic devices to be developed, power-efficient nanolaser diodes able to be integrated densely with silicon photonics and electronics are essential to convert electrical data into the optical domain. Here, we report a demonstration of ultracompact laser diodes based on one-dimensional (1D) photonic crystal (PhC) nanocavities
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,
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made in InP nanoribs heterogeneously integrated on a silicon-waveguide circuitry. The specific nanorib design enables an efficient electrical injection of carriers in the nanocavity without spoiling its optical properties. Room-temperature continuous-wave (CW) single-mode operation is obtained with a low current threshold of 100 µA. Laser emission at 1.56 µm in the silicon waveguides is obtained with wall-plug efficiencies greater than 10%. This result opens up exciting avenues for constructing optical networks at the submillimetre scale for on-chip interconnects and signal processing.
Journal Article
The H19 lincRNA is a developmental reservoir of miR-675 that suppresses growth and Igf1r
The
H19
large intergenic non-coding RNA (lincRNA) is one of the most highly abundant and conserved transcripts in mammalian development, being expressed in both embryonic and extra-embryonic cell lineages, yet its physiological function is unknown. Here we show that miR-675, a microRNA (miRNA) embedded in
H19
’s first exon, is expressed exclusively in the placenta from the gestational time point when placental growth normally ceases, and placentas that lack
H19
continue to grow. Overexpression of miR-675 in a range of embryonic and extra-embryonic cell lines results in their reduced proliferation; targets of the miRNA are upregulated in the
H19
null placenta, including the growth-promoting insulin-like growth factor 1 receptor (
Igf1r
) gene. Moreover, the excision of miR-675 from
H19
is dynamically regulated by the stress-response RNA-binding protein HuR. These results suggest that
H19
’s main physiological role is in limiting growth of the placenta before birth, by regulated processing of miR-675. The controlled release of miR-675 from
H19
may also allow rapid inhibition of cell proliferation in response to cellular stress or oncogenic signals.
Reik and colleagues show that deletion of the large intergenic non-coding RNA H19 leads to unlimited placenta growth. They find that the H19 RNA contains a microRNA that targets the insulin-like growth factor receptor IGF-1R, and demonstrate that the RNA-binding protein HuR prevents miR-675 excision from H19 until miR-675 activity is required to halt placenta growth.
Journal Article
Spontaneous mirror-symmetry breaking in coupled photonic-crystal nanolasers
The observation of symmetry breaking in a coupled nanolaser system could yield new types of switchable devices.
Multi-cavity photonic systems, also known as photonic molecules, exhibit multi-well potentials that may prove useful for advanced quantum and nonlinear optics
1
,
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,
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,
4
. A key phenomenon arising in double-well potentials is the spontaneous breaking of inversion symmetry, with a transition to two localized states in the wells, which are mirror images of each other. Although a few theoretical studies have addressed mirror-symmetry breaking in micro- and nanophotonic systems
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,
7
, no experimental evidence has been reported to date. Here, we demonstrate spontaneous mirror-symmetry breaking through a pitchfork bifurcation in a photonic molecule composed of two coupled photonic-crystal nanolasers. The coexistence of localized states is shown by switching them with short pulses. This offers exciting prospects for the realization of ultra-compact, integrated, scalable optical flip-flops. Analysis suggests that such symmetry breaking should be possible with a small number of intracavity photons and is thus suitable for quantum correlation devices.
Journal Article
The AquaVIT-4 intercomparison of atmospheric hygrometers
The AquaVIT-4 intercomparison of atmospheric hygrometers was conducted at the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) climate simulation chamber of the Karlsruhe Institute of Technology (KIT), Germany, in March–April 2022, within the framework of the HEMERA H2020 EU project. The objectives were to document the performance of existing hygrometers and to support the development of novel methods for water vapor (H2O) measurements in the upper atmosphere. The AquaVIT-4 intercomparison involved seven hygrometers based on either infrared laser absorption spectroscopy or frost-point hygrometry techniques: four deployed on aircraft or stratospheric balloon platforms and three reference instruments. The simulated conditions in the AIDA chamber reproduced the characteristic atmospheric conditions of the upper troposphere–lower stratosphere (UTLS, altitude range ∼ 5–28 km) in the tropics and midlatitudes, spanning 20–600 hPa pressure, 190–245 K temperature, and 0.5–530 ppm H2O mixing ratio. The campaign was divided into two phases, each consisting of 4 measurement days: an “open intercomparison”, where the simulated conditions were known to the participants, and a “blind intercomparison”, where the conditions were coordinated by independent referees and unknown to the participating teams. Here we present a statistical analysis of the entire dataset, which allows us to assess the accuracy and limitations of each instrument. For the accuracy evaluation, two sets of reference measurements were defined: one for in situ instruments, located inside the AIDA vessel, and one for extractive instruments, sampling the chamber gas through a heated inlet. This distinction accounts for H2O desorption effects, which are most prominent at low pressures and low H2O concentrations. All instruments showed good agreement with the reference values in the range of H2O >2 ppm, with mean deviations within ± 7 % for H2O >10 ppm and ± 8 % between 2–10 ppm H2O. The largest differences were found for H2O <2 ppm, a rarely observed range in the atmosphere, though most of the instruments still achieved average deviations within ± 10 %. Overall, the results of AquaVIT-4 demonstrate the high accuracy and reliability of the four involved sensors for upper-atmospheric monitoring and research applications.
Journal Article
H19 IncRNA controls gene expression of the Imprinted Gene Network by recruiting MBD1
The H19 gene controls the expression of several genes within the Imprinted Gene Network (IGN), involved in growth control of the embryo. However, the underlying mechanisms of this control remain elusive. Here, we identified the methyl-CpG–binding domain protein 1 MBD1 as a physical and functional partner of the H19 long noncoding RNA (IncRNA). The H19 IncRNA–MBD1 complex is required for the control of five genes of the IGN. For three of these genes—Igf2 (insulin-like growth factor 2), Slc38a4 (solute carrier family 38 member 4), and Peg1 (paternally expressed gene 1)—both MBD1 and H3K9me3 binding were detected on their differentially methylated regions. The H19 IncRNA–MBD1 complex, through its interaction with histone lysine methyltransferases, therefore acts by bringing repressive histone marks on the differentially methylated regions of these three direct targets of the H19 gene. Our data suggest that, besides the differential DNA methylation found on the differentially methylated regions of imprinted genes, an additional fine tuning of the expressed allele is achieved by a modulation of the H3K9me3 marks, mediated by the association of the H19 IncRNA with chromatin-modifying complexes, such as MBD1. This results in a precise control of the level of expression of growth factors in the embryo.
Journal Article
The H19 locus: regulatory function of an imprinted non coding RNA in embryonic development
Doc number: P54
Journal Article