资源环境科技发展态势分析平台

Conventional information processors convert information between different physical carriers for processing, storage and transmission. It seems plausible that quantum information will also be held by different physical carriers in applications such as tests of fundamental physics, quantum enhanced sensors and quantum information processing. Quantum controlled molecules, in particular, could transduce quantum information across a wide range of quantum bit (qubit) frequencies-from a few kilohertz for transitions within the same rotational manifold(1), a few gigahertz for hyperfine transitions, a few terahertz for rotational transitions, to hundreds of terahertz for fundamental and overtone vibrational and electronic transitions-possibly all within the same molecule. Here we demonstrate entanglement between the rotational states of a (CaH+)-Ca-40 molecular ion and the internal states of a Ca-40(+) atomic ion(2). We extend methods used in quantum logic spectroscopy(1,3) for pure-state initialization, laser manipulation and state readout of the molecular ion. The quantum coherence of the Coulomb coupled motion between the atomic and molecular ions enables subsequent entangling manipulations. The qubit addressed in the molecule has a frequency of either 13.4 kilohertz(1) or 855 gigahertz(3), highlighting the versatility of molecular qubits. Our work demonstrates how molecules can transduce quantum information between qubits with different frequencies to enable hybrid quantum systems. We anticipate that our method of quantum control and measurement of molecules will find applications in quantum information science, quantum sensors, fundamental and applied physics, and controlled quantum chemistry.

Quantum entanglement is realized between rotational levels of a molecular ion with energy differences spanning several orders of magnitude and long-lived internal states of a single atomic ion.

Detection of dopamine dips by neurons that express dopamine D2 receptors in the striatum is used to refine generalized reward conditioning mediated by dopamine D1 receptors.

Dopamine D2 receptors (D2Rs) are densely expressed in the striatum and have been linked to neuropsychiatric disorders such as schizophrenia(1,2). High-affinity binding of dopamine suggests that D2Rs detect transient reductions in dopamine concentration (the dopamine dip) during punishment learning(3-5). However, the nature and cellular basis of D2R-dependent behaviour are unclear. Here we show that tone reward conditioning induces marked stimulus generalization in a manner that depends on dopamine D1 receptors (D1Rs) in the nucleus accumbens (NAc) of mice, and that discrimination learning refines the conditioning using a dopamine dip. In NAc slices, a narrow dopamine dip (as short as 0.4 s) was detected by D2Rs to disinhibit adenosine A(2A) receptor (A(2A)R)-mediated enlargement of dendritic spines in D2R-expressing spiny projection neurons (D2-SPNs). Plasticity-related signalling by Ca2+/calmodulin-dependent protein kinase II and A(2A)Rs in the NAc was required for discrimination learning. By contrast, extinction learning did not involve dopamine dips or D2-SPNs. Treatment with methamphetamine, which dysregulates dopamine signalling, impaired discrimination learning and spine enlargement, and these impairments were reversed by a D2R antagonist. Our data show that D2Rs refine the generalized reward learning mediated by D1Rs.

An in vivo approach to identify proteins whose enrichment near cardiac Ca(V)1.2 channels changes upon beta-adrenergic stimulation finds the G protein Rad, which is phosphorylated by protein kinase A, thereby relieving channel inhibition by Rad and causing an increased Ca2+ current.

Increased cardiac contractility during the fight-or-flight response is caused by beta-adrenergic augmentation of Ca(V)1.2 voltage-gated calcium channels(1-4). However, this augmentation persists in transgenic murine hearts expressing mutant Ca(V)1.2 alpha(1C) and beta subunits that can no longer be phosphorylated by protein kinase A-an essential downstream mediator of beta-adrenergic signalling-suggesting that non-channel factors are also required. Here we identify the mechanism by which beta-adrenergic agonists stimulate voltage-gated calcium channels. We express alpha(1C) or beta(2B) subunits conjugated to ascorbate peroxidase(5) in mouse hearts, and use multiplexed quantitative proteomics(6,7) to track hundreds of proteins in the proximity of Ca(V)1.2. We observe that the calcium-channel inhibitor Rad(8,9), a monomeric G protein, is enriched in the Ca(V)1.2 microenvironment but is depleted during beta-adrenergic stimulation. Phosphorylation by protein kinase A of specific serine residues on Rad decreases its affinity for beta subunits and relieves constitutive inhibition of Ca(V)1.2, observed as an increase in channel open probability. Expression of Rad or its homologue Rem in HEK293T cells also imparts stimulation of Ca(V)1.3 and Ca(V)2.2 by protein kinase A, revealing an evolutionarily conserved mechanism that confers adrenergic modulation upon voltage-gated calcium channels.

The CRISPR system in bacteria and archaea provides adaptive immunity against mobile genetic elements. Type III CRISPR systems detect viral RNA, resulting in the activation of two regions of the Cas10 protein: an HD nuclease domain (which degrades viral DNA)(1,2) and a cyclase domain (which synthesizes cyclic oligoadenylates from ATP)(3-5). Cyclic oligoadenylates in turn activate defence enzymes with a CRISPR-associated Rossmann fold domain(6), sculpting a powerful antiviral response(7-10) that can drive viruses to extinction(7,8). Cyclic nucleotides are increasingly implicated in host-pathogen interactions(11-13). Here we identify a new family of viral anti-CRISPR (Acr) enzymes that rapidly degrade cyclic tetra-adenylate (cA(4)). The viral ring nuclease AcrIII-1 is widely distributed in archaeal and bacterial viruses and in proviruses. The enzyme uses a previously unknown fold to bind cA(4) specifically, and a conserved active site to rapidly cleave this signalling molecule, allowing viruses to neutralize the type III CRISPR defence system. The AcrIII-1 family has a broad host range, as it targets cA(4) signalling molecules rather than specific CRISPR effector proteins. Our findings highlight the crucial role of cyclic nucleotide signalling in the conflict between viruses and their hosts.