Specification of axial identity by Hoxa2 distinguishes between a phenotypic and molecular ground state in mouse cranial neural crest cells

Hox genes play a key role in head formation by specifying the axial identity of neural crest cells (NCCs) migrating into embryonic pharyngeal arches. In the absence of Hoxa2, NCC derivatives of the second pharyngeal arch (PA2) undergo a homeotic transformation and duplicate structures formed by first arch (PA1) NCCs. Current models postulate that PA1 represents a NCC ‘ground state’ and loss of Hoxa2 causes a reversion of PA2 NCCs to the PA1 ‘ground state’. We use bulk and single-cell RNAseq to investigate the molecular mechanisms driving this phenotypic transformation in the mouse. In Hoxa2-/- mutants, PA2 NCCs generally maintain expression of the PA2 transcriptional signature and fail to strongly upregulate a PA1 transcriptional signature. Our analyses identify putative HOXA2 targets and suggest that subsets of NCCs may respond to HOXA2 activity in distinct manners. This separation of phenotypic and molecular states has significant implications for understanding craniofacial development.

Quantum computing simulation of the hydrogen molecular ground-state energies with limited resources

In this article, the hydrogen molecular ground-state energies using our algorithm based on quantum variational principle are calculated. They are calculated through a simulator since the system of the present study (i.e., the hydrogen molecule) is relatively small and hence the ground-state energies for this molecule are efficiently classically simulable using a simulator. Complete details of this algorithm are elucidated. For this, a full description on the fermions–qubits and the molecular Hamiltonian–qubit Hamiltonian transformations, is given. The authors search for qubit system parameters ( θ 0 {\theta }_{0} and θ 1 {\theta }_{1} ) that yield the minimum energies for the system and also study the ground state energies as a function of the molecular bond length. Proposed circuit is humble and does not include many parameters compared with that of Kandala et al., the authors control only two parameters ( θ 0 {\theta }_{0} and θ 1 {\theta }_{1} ).

Structural, spectroscopic and first-principles studies of new aminocoumarin derivatives

The new aminocoumarin derivatives 3-[1-(3-hydroxyanilino)ethylidene]-3H-chromene-2,4-dione, (1), 3-[1-(4-hydroxyanilino)ethylidene]-3H-chromene-2,4-dione, (2), and 3-[1-(2-hydroxyanilino)ethylidene]-3H-chromene-2,4-dione, (3), all C17H13NO4, were synthesized by reacting an equimolar amount of 3-acetyl-4-hydroxycoumarin and the corresponding aminophenol in absolute ethanol. Structural and spectroscopic analysis of these phases revealed that derivatives (1) and (2) are isomers of previously reported (3) [Brahmia et al. (2013). Acta Cryst. E69, o1296]. The crystal structures of meta derivative (1) and para derivative (2) were ab initio determined from powder X-ray diffraction data using the direct-space approach. Both (1) and (2) adopt the orthorhombic space group P212121. These isomers show hydrogen bonds and rich π–π stacking, together with π...H interactions, which are built by conjugated systems of coumarin and phenol rings. In the crystalline lattice, the packing of (1) and (3) are mainly stabilized through O—H...O hydrogen bonding between neighbouring coumarin molecules, while hydrogen bonds between coumarin and water molecules build the stable crystal structure of derivative (2). A big similarity in the skeletons of the IR spectra of these isomers was noticed. Derivative (2) exhibits two weak bands which were not present in the spectra of the other two derivatives, at 2370 and 2948 cm−1, which can be assigned to the O—H vibrations of the solvent (H2O) trapped in the structure of (2). These aminocoumarin derivatives display absorption maxima in the visible region, attributed to π–π delocalization involving the whole electronic system of the compounds with a considerable charge-transfer character originating from the aminophenyl ring and pointing towards the coumarin system which is characterized by a high electron-accepting character. Additionally, the isolated molecular ground-state geometries were optimized at the PBE0/TZP level and the electronic properties, molecular electrostatic potential and Hirshfeld charges were determined.

Fluorescence anisotropy in indole under two-photon excitation in the spectral range 385–510 nm

This paper presents the detailed study of two-photon excited fluorescence in indole dissolved in propylene glycol produced by two-photon absorption from the molecular ground state to several high lying excited states.