Dynamics of magnetization at infinite temperature in a Heisenberg spin chain

Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the one-dimensional Heisenberg model were conjectured as to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we studied the probability distribution of the magnetization transferred across the chain's center, [Formula: see text]. The first two moments of [Formula: see text] show superdiffusive behavior, a hallmark of KPZ universality. However, the third and fourth moments ruled out the KPZ conjecture and allow for evaluating other theories. Our results highlight the importance of studying higher moments in determining dynamic universality classes and provide insights into universal behavior in quantum systems.

Stable quantum-correlated many-body states through engineered dissipation

Engineered dissipative reservoirs have the potential to steer many-body quantum systems toward correlated steady states useful for quantum simulation of high-temperature superconductivity or quantum magnetism. Using up to 49 superconducting qubits, we prepared low-energy states of the transverse-field Ising model through coupling to dissipative auxiliary qubits. In one dimension, we observed long-range quantum correlations and a ground-state fidelity of 0.86 for 18 qubits at the critical point. In two dimensions, we found mutual information that extends beyond nearest neighbors. Lastly, by coupling the system to auxiliaries emulating reservoirs with different chemical potentials, we explored transport in the quantum Heisenberg model. Our results establish engineered dissipation as a scalable alternative to unitary evolution for preparing entangled many-body states on noisy quantum processors.

Investigation of the Potential Mechanism of Compound Dragon's Blood Capsule against Myocardial IschemiaBased on Network Pharmacology

BACKGROUND

Dragon's blood is widely consumed in China, Vietnam and Laos to promote blood circulation. A Compound Dragon's blood capsule (CDC) is a patented medicine composed of dragon's blood, notoginseng, and borneol. This combination is purported to stabilize coronary heart disease and myocardial ischemia. However, the possible mechanisms and the characterization of its drug targets' relevance at the systemic level remain unclear.

AIM

The present study aims to reveal the potential mechanisms of CDC's anti-myocardial ischemia effect.

MATERIALS AND METHODS

The potential mechanisms were investigated by network pharmacology and qRT-PCR was used to verify the expression levels of key genes of PI3k-Akt pathway.

RESULTS

S1PR2 and AGTR1 were the common targets, which involved 6 biological processes annotated by KEGG and GO analysis. The qRT-PCR results showed a remarkable increase in the expression of Pi3k, Pdk1, Akt, Mdm2, Bcl2, and mTOR. Results also showed a decline in the expression of P53 and Casp3 after CDC intervention.

CONCLUSION

CDC has a significant anti-myocardial ischemia effect through the PI3k/Akt pathway, which demonstrates that CDC is a suitable adjuvant to treat CHD and provides a theoretical basis for its further clinical application.

Prognostic implication of a novel lactate score correlating with immunotherapeutic responses in pan-cancer

A thorough assessment of lactate-related genes (LRGs) in different types of human cancers is currently lacking. To elucidate the molecular landscape of LRGs, we conducted a comprehensive analysis using genomic, mRNA, and microRNA expression profiles and developed a lactate score model using the least absolute shrinkage and selection operator (LASSO) algorithm. We found that our lactate score could be a prognostic marker instead of LDHA for several cancer patients who possess high-frequency variants in LRGs. The lactate score also demonstrated an association with CD8+ T cells infiltration in multiple cancer types. Furthermore, our findings indicate that the lactate score holds promise as a potential biomarker for immunotherapy in patients with bladder cancer (BLCA) and skin cutaneous melanoma (SKCM). Among the seventeen genes of the lactate score model, PDP1 showed the strongest positive correlation with lactate score and the potential as a standalone biomarker for prognosis. In general, our study has yielded crucial insights into the potential application of the lactate score as a predictive biomarker for both survival outcomes and the response to immunotherapy. By recognizing the prognostic significance of lactate metabolism, we open avenues for further investigations aimed at harnessing the therapeutic potential of lactate.

Glycyrrhetinic Acid Receptor-Mediated Zeolitic Imidazolate Framework-8 Loaded Doxorubicin as a Nanotherapeutic System for Liver Cancer Treatment

In this study, we designed and developed a DOX nanodrug delivery system (PEG-GA@ZIF-8@DOX) using ZIF-8 as the carrier and glycyrrhetinic acid (GA) as the targeting ligand. We confirmed that DOX was loaded and PEG-GA was successfully modified on the surface of the nanoparticles. The in vitro release profile of the system was investigated at pH 5.0 and 7.4. The cellular uptake, in vitro cytotoxicity, and lysosomal escape characteristics were examined using HepG2 cells. We established an H22 tumor-bearing mouse model and evaluated the in vivo antitumor activity. The results showed that the system had a uniform nanomorphology. The drug loading capacity was 11.22 ± 0.87%. In acidic conditions (pH 5.0), the final release rate of DOX was 57.73%, while at pH 7.4, it was 25.12%. GA-mediated targeting facilitated the uptake of DOX by the HepG2 cells. PEG-GA@ZIF-8@DOX could escape from the lysosomes and release the drug in the cytoplasm, thus exerting its antitumor effect. When the in vivo efficacy was analyzed, we found that the tumor inhibition rate of PEG-GA@ZIF-8@DOX was 67.64%; it also alleviated the loss of the body weight of the treated mice. This drug delivery system significantly enhanced the antitumor effect of doxorubicin in vitro and in vivo, while mitigating its toxic side effects.

Measurement-induced entanglement and teleportation on a noisy quantum processor

Measurement has a special role in quantum theory1: by collapsing the wavefunction, it can enable phenomena such as teleportation2 and thereby alter the 'arrow of time' that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space-time3-10 that go beyond the established paradigms for characterizing phases, either in or out of equilibrium11-13. For present-day noisy intermediate-scale quantum (NISQ) processors14, the experimental realization of such physics can be problematic because of hardware limitations and the stochastic nature of quantum measurement. Here we address these experimental challenges and study measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping9,15-17 to avoid mid-circuit measurement and access different manifestations of the underlying phases, from entanglement scaling3,4 to measurement-induced teleportation18. We obtain finite-sized signatures of a phase transition with a decoding protocol that correlates the experimental measurement with classical simulation data. The phases display remarkably different sensitivity to noise, and we use this disparity to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realizing measurement-induced physics at scales that are at the limits of current NISQ processors.

Complement and coagulation cascades pathway-related signature as a predictor of immunotherapy in metastatic urothelial cancer

BACKGROUND

Immune checkpoint inhibitors (ICIs) have shown efficacy in patients with metastatic urothelial cancer (mUC), however, only a small subset of patients could benefit from ICIs. Identifying predictive biomarkers of ICIs in patients with mUC is clinical meaningful for patient stratification and administration.

METHODS

Clinical and transcriptomic data of mUC patients treated with ICIs from mUC cohort (IMvigor210 study) was utilized to explore the predictive biomarkers. LASSO Cox regression was performed to construct a predictive model. The predictive model was trained and tested in the mUC cohort, and then exploratively tested in clear cell renal cell carcinoma (ccRCC) and melanoma cohorts in which patients also received ICIs regimens.

RESULTS

The differentially expressed genes (DEGs) in complement and coagulation cascades pathway (CCCP) were mainly enriched in non-responders of ICIs in the mUC cohort. A CCCP risk score was constructed based on the DEGs in CCCP. Patients with a low-risk score were more responsive to ICIs and had better overall survival (OS) than those with a high-risk score in the training set (HR, 0.38; 95%CI, 0.27-0.53, P<0.001) and the test set (HR, 0.34; 95%CI, 0.17-0.71, P=0.003). The association between the CCCP risk score and OS remained significant in the multivariable cox regression by adjusting PD-L1 expression and TMB (P<0.05). In addition, there was no difference for OS in the bladder cancer patients without ICIs (TCGA-BLCA cohort, HR, 0.76, 95%CI, 0.49-1.18, P=0.22), suggesting a predictive but not prognostic effect of the risk score. For the exploratory analysis, consistent results were observed that low-risk group showed superior OS in ccRCC cohort (HR, 0.52, 95%CI, 0.37-0.75, P<0.001) and melanoma cohort (HR, 0.27, 95%CI, 0.12-0.62, P=0.001).

CONCLUSIONS

Our study showed that the CCCP risk score is an independent biomarker that predicts the efficacy of ICIs in mUC patients. The patients with a low-risk score tend to have a better response to ICIs and a longer life time probably due to the immune-activated TME. Further studies are needed to validate the clinical utility of the seven-gene signature.

Non-Abelian braiding of graph vertices in a superconducting processor

Indistinguishability of particles is a fundamental principle of quantum mechanics¹. For all elementary and quasiparticles observed to date-including fermions, bosons and Abelian anyons-this principle guarantees that the braiding of identical particles leaves the system unchanged^2,3. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotations in a space of topologically degenerate wavefunctions^4-8. Hence, it can change the observables of the system without violating the principle of indistinguishability. Despite the well-developed mathematical description of non-Abelian anyons and numerous theoretical proposals^9-22, the experimental observation of their exchange statistics has remained elusive for decades. Controllable many-body quantum states generated on quantum processors offer another path for exploring these fundamental phenomena. Whereas efforts on conventional solid-state platforms typically involve Hamiltonian dynamics of quasiparticles, superconducting quantum processors allow for directly manipulating the many-body wavefunction by means of unitary gates. Building on predictions that stabilizer codes can host projective non-Abelian Ising anyons^9,10, we implement a generalized stabilizer code and unitary protocol²³ to create and braid them. This allows us to experimentally verify the fusion rules of the anyons and braid them to realize their statistics. We then study the prospect of using the anyons for quantum computation and use braiding to create an entangled state of anyons encoding three logical qubits. Our work provides new insights about non-Abelian braiding and, through the future inclusion of error correction to achieve topological protection, could open a path towards fault-tolerant quantum computing.

Hyperprogressive disease after immune checkpoint inhibitor therapy in a patient with non‑small cell lung cancer who harbors a TGFBR2 mutation: A case report

We previously demonstrated that a transforming growth factor β type II receptor (TGFBR2) mutation can predict resistance to immune checkpoint inhibitors (ICIs) in patients with advanced non-small cell lung cancer (NSCLC), based on publicly available immunotherapeutic cohorts. However, the efficacy of ICI-based regimens in patients with advanced NSCLC harboring TGFBR2 mutations in the real-world setting is rarely reported. The present study describes the case of a patient with advanced NSCLC who harbors a TGFBR2 mutation. The patient was treated with ICI monotherapy and experienced hyperprogressive disease (HPD). The clinical information was retrospectively collected. The progression-free survival (PFS) was only 1.3 months. In conclusion, HPD occurred in a patient with advanced NSCLC with a TGFBR2 mutation who received an ICI monotherapy regimen. The findings suggested that caution may be required regarding the clinical delivery of ICI monotherapy to patients with NSCLC and TGFBR2 mutations; ICIs combined with chemotherapy may be an alternative treatment option.

A pyroptosis-related gene signature for prognosis prediction in hepatocellular carcinoma

Introduction

Hepatocellular carcinoma (HCC) is one of the most invasive cancers with a low 5-year survival rate. Pyroptosis, a specialized form of cell death, has shown its association with cancer progression. However, its role in the prognosis of HCC has not been fully understood.

Methods

In our study, clinical information and mRNA expression for 1076 patients with HCC were obtained from the five public cohorts. Pyroptotic clusters were generated by unsupervised clustering based on 40 pyroptosis-related genes (PRGs) in the TCGA and ICGC cohort. A pyroptosis-related signature was constructed using least absolute shrinkage and selection operator (LASSO) regression according to differentially expressed genes (DEGs) of pyroptotic clusters. The signature was then tested in the validation cohorts (GES10142 and GSE14520) and subsequently validated in the CPTAC cohort (n=159) at both mRNA and protein levels. Response to sorafenib was explored in GSE109211.

Results

Three clusters were identified based on the 40 PRGs in the TCGA cohort. A total of 24 genes were selected based on DEGs of the above three pyroptotic clusters to construct the pyroptotic risk score. Patients with the high-risk score showed shorter overall survival (OS) compared to those with the low-risk score in the training set (P&lt;0.001; HR, 3.06; 95% CI, 2.22-4.24) and the test set (P=0.008; HR, 1.61; 95% CI, 1.13-2.28). The predictive ability of the risk score was further confirmed in the CPTAC cohort at both mRNAs (P&lt;0.001; HR, 2.99; 95% CI, 1.67-5.36) and protein levels (P&lt;0.001; HR, 2.97; 95% CI 1.66-5.31). The expression of the model genes was correlated with immune cell infiltration, angiogenesis-related genes, and sensitivity to antiangiogenic therapy (P&lt;0.05).

Discussion

In conclusion, we established a prognostic signature of 24 genes based on pyroptosis clusters for HCC patients, providing insight into the risk stratification of HCC.

Formation of robust bound states of interacting microwave photons

Systems of correlated particles appear in many fields of modern science and represent some of the most intractable computational problems in nature. The computational challenge in these systems arises when interactions become comparable to other energy scales, which makes the state of each particle depend on all other particles1. The lack of general solutions for the three-body problem and acceptable theory for strongly correlated electrons shows that our understanding of correlated systems fades when the particle number or the interaction strength increases. One of the hallmarks of interacting systems is the formation of multiparticle bound states2-9. Here we develop a high-fidelity parameterizable fSim gate and implement the periodic quantum circuit of the spin-½ XXZ model in a ring of 24 superconducting qubits. We study the propagation of these excitations and observe their bound nature for up to five photons. We devise a phase-sensitive method for constructing the few-body spectrum of the bound states and extract their pseudo-charge by introducing a synthetic flux. By introducing interactions between the ring and additional qubits, we observe an unexpected resilience of the bound states to integrability breaking. This finding goes against the idea that bound states in non-integrable systems are unstable when their energies overlap with the continuum spectrum. Our work provides experimental evidence for bound states of interacting photons and discovers their stability beyond the integrability limit.

Noise-resilient edge modes on a chain of superconducting qubits

Inherent symmetry of a quantum system may protect its otherwise fragile states. Leveraging such protection requires testing its robustness against uncontrolled environmental interactions. Using 47 superconducting qubits, we implement the one-dimensional kicked Ising model, which exhibits nonlocal Majorana edge modes (MEMs) with ℤ 2 parity symmetry. We find that any multiqubit Pauli operator overlapping with the MEMs exhibits a uniform late-time decay rate comparable to single-qubit relaxation rates, irrespective of its size or composition. This characteristic allows us to accurately reconstruct the exponentially localized spatial profiles of the MEMs. Furthermore, the MEMs are found to be resilient against certain symmetry-breaking noise owing to a prethermalization mechanism. Our work elucidates the complex interplay between noise and symmetry-protected edge modes in a solid-state environment.

A Combined Catalytic Ozonation-MBR Approach to Remove Contaminants from the Mature Landfill Leachate in the Yellow River Basin

The mature landfill leachate (MLL) is characterized by a large number of fulvic acids and humic acids, which is refractory organic matter and can be cleaned by ozone oxidation. However, the poor property of mass transfer prohibits the widespread use of ozone oxidation in actual leachate treatment. Meanwhile, some combined processes are adopted to treat the mature landfill leachate, which places catalytic ozonation before the membrane bioreactor (MBR) process to enhance the biodegradability of MLL. Thus, this research is conducted to investigate the practicability of applying nano-Fe₃O₄ loaded cow-dung ash (Fe₃O₄@CDA) and biological post-treatment with MBR for the effective removal of pollutants from MLL and puts forward the variation of organics in leachate between catalytic ozonation and MBR. The addition of catalytic ozonation not only improved the removal of hazardous organics but also enhanced the biodegradability of the leachate and favored the subsequent MBR process. Chemical oxygen demand (COD) removal in the catalytic ozonation step was optimized, and 53% removal was obtained at pH = 7, catalyst dosage = 1.0 g/L, and O₃ dosage = 3.0 g/L. After the MBR process, COD in effluent stabilized in the range of 57.85-65.38 mg/L, and the variation range of the ammonia nitrogen (NH₃-N) concentration was 5.98-10.24 mg/L. The catalytic ozonation-MBR integrated process showed strong feasibility in dealing with the biologically pre-treated leachate.

The Protective Effect of Trichilia catigua A. Juss. on DEHP-Induced Reproductive System Damage in Male Mice

The present study aimed to explore the protective effect and molecular mechanisms of Trichilia catigua A. Juss. extract (TCE) against di (2-ethylhexyl) phthalate (DEHP)-induced damage to the reproductive system of mice. Acute toxicity tests revealed that the maximum tolerated dose (MTD) in mice was up to 2.7 g kg⁻¹. After induction with DEHP, TCE (L-TCE, M-TCE, H-TCE) was orally administered to mice for 28 days. Differences in indicators among groups showed that TCE significantly improved the anogenital distance and the organ indexes of the epididymides and testes. It also significantly reduced varicocele and interstitial cell lesions compared to the model group. H-TCE reduced the sperm abnormality rate, increased the levels of sex hormones, Na⁺K⁺ and Mg²⁺, Ca²⁺-ATPase enzyme activity, antioxidant enzyme vitality, coupled with a significant decrease in LH and MDA contents. The levels of testicular marker enzymes ACP and LDH were significantly augmented by both M-TCE and H-TCE. Further studies claimed that DEHP induction reduced the mRNA expression levels of Nrf2, SOD2, SOD3, CDC25C CDK1, CYP11A1, 3β-HSD, 5ɑ-R, AR, SF1, and CYP17A1, increased the level of Keap1, while TCE reversed the expression levels of these genes. Meanwhile, IHC results demonstrated a significant change in the expression activity of the relevant proteins compared to the control group. The results suggest that M-TCE and H-TCE enabled the recovery of DEHP-induced reproductive system damage in male mice by improving testicular histopathology, repairing testicular function, and reducing oxidative stress damage. The oxidation-related Keap1-Nrf2 pathway, SODs enzyme, the cell cycle control-related CDC25C-CDK1 pathway, and the steroidogenic-related pathway may contribute to this protective effects of TCE.

Folic Acid Decorated Zeolitic Imidazolate Framework (ZIF-8) Loaded with Baicalin as a Nano-Drug Delivery System for Breast Cancer Therapy

Background

Baicalin (BAN) has attracted widespread attention due to its low-toxicity and efficient antitumor activity, but its poor water solubility and low bioavailability severely limit its clinical application. Development of a targeted drug delivery system is a good strategy to improve the antitumor activity of baicalin.

Methods

We prepared a BAN nano-drug delivery system PEG-FA@ZIF-8@BAN with a zeolite imidazole framework-8 (ZIF-8) as a carrier, which can achieve the response of folate receptor (FR). We characterized this system in terms of morphology, particle size, zeta-potential, infrared (IR), ultraviolet (UV), x-ray diffraction (XRD), and Brunel-Emmett-Teller (BET), and examined the in vitro cytotoxicity and cellular uptake properties of PEG-FA@ZIF-8@BAN using MCF-7 cells. Lastly, we established a 4T1 tumor-bearing mouse model and evaluated its in vivo anti-mammary cancer activity.

Results

The PEG-FA@ZIF-8@BAN nano-delivery system had good dispersion with a BAN loading efficiency of 41.45 ± 1.43%, hydrated particle size of 176 ± 8.1 nm, Zeta-potential of −23.83 ± 1.1 mV, and slow and massive drug release in an acidic environment (pH 5.0), whereas release was 11.03% in a neutral environment (pH 7.4). In vitro studies showed that PEG-FA@ZIF-8@BAN could significantly enhance the killing effect of BAN on MCF-7 cells, and the folic acid-mediated targeting could lead to better uptake of nanoparticles by tumor cells and thus better killing of cancer cells. In vivo studies also showed that PEG-FA@ZIF-8@BAN significantly increased the inhibition of the proliferation of solid breast cancer tumors (p < 0.01 or p < 0.001).

Conclusion

The PEG-FA@ZIF-8@BAN nano-drug delivery system significantly enhanced the anti-breast cancer effect of baicalin both in vivo and in vitro, providing a more promising drug delivery system for the clinical applications and tumor management.

Minimal solutions of fuzzy relation inequalities with addition-min composition1

This paper investigates minimal solutions of fuzzy relation inequalities with addition-min composition. It first shows the conditions that an element is a minimal solution of the inequalities, and presents the conditions that the inequalities have a unique minimal solution. It then proves that every solution of the inequalities has a minimal one and proposes an algorithm to searching for a minimal solution with computational complexity O (n2) where n is the number of unknown variables of the inequalities. This paper finally describes all minimal solutions of the inequalities.

Realizing topologically ordered states on a quantum processor

[Figure: see text].

Time-Crystalline Eigenstate Order on a Quantum Processor

Quantum many-body systems display rich phase structure in their low-temperature equilibrium states¹. However, much of nature is not in thermal equilibrium. Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases^2–8 that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC)^7,9–15. Concretely, dynamical phases can be defined in periodically driven many-body-localized (MBL) systems via the concept of eigenstate order^7,16,17. In eigenstate-ordered MBL phases, the entire many-body spectrum exhibits quantum correlations and long-range order, with characteristic signatures in late-time dynamics from all initial states. It is, however, challenging to experimentally distinguish such stable phases from transient phenomena, or from regimes in which the dynamics of a few select states can mask typical behaviour. Here we implement tunable controlled-phase (CPHASE) gates on an array of superconducting qubits to experimentally observe an MBL-DTC and demonstrate its characteristic spatiotemporal response for generic initial states^7,9,10. Our work employs a time-reversal protocol to quantify the impact of external decoherence, and leverages quantum typicality to circumvent the exponential cost of densely sampling the eigenspectrum. Furthermore, we locate the phase transition out of the DTC with an experimental finite-size analysis. These results establish a scalable approach to studying non-equilibrium phases of matter on quantum processors.

A study establishes a scalable approach to engineer and characterize a many-body-localized discrete time crystal phase on a superconducting quantum processor.

Information scrambling in quantum circuits

[Figure: see text].

Comparative study of the distribution and expression of Neuroglobin and Hypoxia-inducible factor-1α in the adult and young Yak Brain

BACKGROUND

The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals.

AIM

The study examined the expression of Neuroglobin (Ngb) and Hypoxia-inducible factor-1α (Hif-1α) in adult and young yak brain tissues, and provided researchers with meaningful insight into the anatomy, physiology, and biochemistry of this mammal.

METHOD

The study employed immunohistochemistry (IHC), quantitative real-time PCR (qRT-PCR), and Western blot (WB) to obtain the results.

RESULTS

Ngb and Hif-1α were significantly (P<0.05) expressed in the cerebellar cortex, piriform lobe, medulla, and corpus callosum of the adult yak while in the young yak brain tissues, the protein expressions were significantly found in the white matter of the cerebellum, pineal gland, corpus callosum, and cerebellar cortex. The Ngb and Hif-1α expression showed similarities and differences. This may have resulted from similar animal species, source of nutrition, age factors, brain size, emotional activities, and communication. The findings documented that Ngb and Hif-1α are commonly expressed in various adult and young yak brain tissues. Multiple roles in the brain tissues of the adult and young yaks are involved in the expression and distribution and are proposed to play a significant role in the adaptation of the yak to the high altitude environment.

CONCLUSION

This study provides meaningful data to understand the adaptive mechanism to hypoxia and recommended researchers to expand on the adaptive mechanism and brain tissues that are not recorded.

Comparative study on the distribution and expression of Neuroglobin and Hypoxia-inducible factor-1α in the telencephalon of yak and cattle

The telencephalon refers to the most highly developed and anterior part of the forebrain, consisting mainly of the cerebral hemispheres. The study determined Neuroglobin (Ngb) and Hypoxia-inducible factor (HIF-1α) expression in the telencephalon of yak and cattle, and compare the expression and distribution pattern of Ngb and HIF-1α in the two animals. Immunohistochemistry (IHC), quantitative real-time Polymerase Chain Reaction (qRT-PCR), and Western blot (WB) were employed to investigate Ngb and Hif-1α expression in the telencephalon of yak and cattle. mRNA and protein expressions of Ngb and HIF-1α showed positive in different tissues of the yak and cattle telencephalon. Ngb expression in tissues of the yak recorded higher as compare to cattle while HIF-1α expression was found higher in cattle than yak. The HIF-1α expression in some tissues of yak telencephalon was consistent with the cattle. The results documented that HIF-1α may have a direct or indirect synergistic effect on Ngb expression in the yak telencephalon to improve hypoxia adaptation. It is suggested that yak may need more Ngb expression for adaptation, but the expression of HIF-1α seems to be down-regulated during long-term adaptation, and the specific causes of this phenomenon needs to be further verified.

Removing leakage-induced correlated errors in superconducting quantum error correction

Quantum computing can become scalable through error correction, but logical error rates only decrease with system size when physical errors are sufficiently uncorrelated. During computation, unused high energy levels of the qubits can become excited, creating leakage states that are long-lived and mobile. Particularly for superconducting transmon qubits, this leakage opens a path to errors that are correlated in space and time. Here, we report a reset protocol that returns a qubit to the ground state from all relevant higher level states. We test its performance with the bit-flip stabilizer code, a simplified version of the surface code for quantum error correction. We investigate the accumulation and dynamics of leakage during error correction. Using this protocol, we find lower rates of logical errors and an improved scaling and stability of error suppression with increasing qubit number. This demonstration provides a key step on the path towards scalable quantum computing.

Akkermansia muciniphila: A potential novel mechanism of nuciferine to improve hyperlipidemia

BACKGROUND

Intestinal microbiota is a novel drug target of metabolic diseases, especially for those with poor oral bioavailability. Nuciferine, with poor bioavailability, has an anti-hyperlipidemic effect at low dosages.

PURPOSE

In the present study, we aimed to explore the role of intestinal microbiota in the anti-hyperlipidemic function of nuciferine and identify the key bacterial targets that might confer the therapeutic actions.

METHODS

The contribution of gut microbes in the anti-hyperlipidemic effect of nuciferine was evaluated by conventional and antibiotic-established pseudo-sterile mice. Whole-metagenome shotgun sequencing was used to characterize the changes in microbial communities by various agents.

RESULTS

Nuciferine exhibited potent anti-hyperlipidemic and liver steatosis-alleviating effects at the doses of 7.5-30 mg/kg. The beneficial effects of nuciferine were substantially abolished when combined with antibiotics. Metagenomic analysis showed that nuciferine significantly shifted the microbial structure, and the enrichment of Akkermansia muciniphila was closely related to the therapeutic effect of nuciferine.

CONCLUSIONS

Our results revealed that gut microbiota played an essential role in the anti-hyperlipidemic effect of nuciferine, and enrichment of Akkermansia muciniphila represented a key mechanism through which nuciferine exerted its therapeutic effects.

Demonstrating a Continuous Set of Two-Qubit Gates for Near-Term Quantum Algorithms

Quantum algorithms offer a dramatic speedup for computational problems in material science and chemistry. However, any near-term realizations of these algorithms will need to be optimized to fit within the finite resources offered by existing noisy hardware. Here, taking advantage of the adjustable coupling of gmon qubits, we demonstrate a continuous two-qubit gate set that can provide a threefold reduction in circuit depth as compared to a standard decomposition. We implement two gate families: an imaginary swap-like (iSWAP-like) gate to attain an arbitrary swap angle, θ, and a controlled-phase gate that generates an arbitrary conditional phase, ϕ. Using one of each of these gates, we can perform an arbitrary two-qubit gate within the excitation-preserving subspace allowing for a complete implementation of the so-called Fermionic simulation (fSim) gate set. We benchmark the fidelity of the iSWAP-like and controlled-phase gate families as well as 525 other fSim gates spread evenly across the entire fSim(θ,ϕ) parameter space, achieving a purity-limited average two-qubit Pauli error of 3.8×10^{-3} per fSim gate.

Hartree-Fock on a superconducting qubit quantum computer

The simulation of fermionic systems is among the most anticipated applications of quantum computing. We performed several quantum simulations of chemistry with up to one dozen qubits, including modeling the isomerization mechanism of diazene. We also demonstrated error-mitigation strategies based on N-representability that dramatically improve the effective fidelity of our experiments. Our parameterized ansatz circuits realized the Givens rotation approach to noninteracting fermion evolution, which we variationally optimized to prepare the Hartree-Fock wave function. This ubiquitous algorithmic primitive is classically tractable to simulate yet still generates highly entangled states over the computational basis, which allowed us to assess the performance of our hardware and establish a foundation for scaling up correlated quantum chemistry simulations.

miR-18a expression in basal cell carcinoma and regulatory mechanism on autophagy through mTOR pathway

BACKGROUND

Basal cell carcinoma (BCC) is the most common form of skin carcinoma.

AIM

To investigate the function of key micro(mi)RNAs and to explore the potential molecular mechanisms involved in BCC.

METHODS

The microarray dataset GSE34535, which comprises seven BCC samples and seven control samples, was downloaded from the Gene Expression Omnibus database. Differentially expressed miRNAs (DE-miRNAs) were identified. We collected tissue samples from 20 patients with BCC and 20 healthy controls (HCs), to compare the miR-18a expression in their tissue samples. Expression of miR-18a in A431 and HaCaT cells was also assayed. Following this, we upregulated and downregulated miR-18a expression in A431 cells to examine the effects on cell proliferation, migration and apoptosis. To further investigate the relative mechanism, the proteins LC3, Beclin 1, Akt and mammalian target of rapamycin (mTOR) were examined by quantitative real-time PCR and Western blotting. For further verification, we examined the expression of LC3 in the 20 BCC and 20 HC tissue samples.

RESULTS

In total, 19 DE-miRNAs (13 upregulated and 6 downregulated) that were common to the BCC and HC groups were identified. Levels of miR-18a were about three-fold higher in BCC tissues and A431 cells compared with their respective control groups. In vitro, downregulation of miR-18a was shown to inhibit cell proliferation and activate autophagy via the Akt/mTOR signalling pathway, while upregulation of miR-18a promoted proliferation of these cells. LC3 was decreased in BCC compared with HC tissue samples.

CONCLUSIONS

Our data support an oncogenic role of miR-18a through a novel Akt/mTOR/Beclin 1/LC3 axis, and suggest that the antitumour effects of miR-18a inhibitor may make it suitable for BCC therapy.

Diabatic Gates for Frequency-Tunable Superconducting Qubits

We demonstrate diabatic two-qubit gates with Pauli error rates down to 4.3(2)×10^{-3} in as fast as 18 ns using frequency-tunable superconducting qubits. This is achieved by synchronizing the entangling parameters with minima in the leakage channel. The synchronization shows a landscape in gate parameter space that agrees with model predictions and facilitates robust tune-up. We test both iswap-like and cphase gates with cross-entropy benchmarking. The presented approach can be extended to multibody operations as well.

Detection and differential diagnosis of cancer relapse using circulating tumor DNA profiling in a patient with synchronous breast and rectal cancer

Background: In Chinese women, breast and colorectal cancers are highly prevalent. In the early stage, the primary treatment for these cancers is surgical resection. However, many patients develop a metastatic recurrence. Thus, tools that help estimate the risk of recurrence are critical. Although synchronous breast and rectal cancer is uncommon, estimating recurrence risk is even more challenging in patients with two histologically distinct malignancies. Methods: Next generation sequencing (NGS) allows the comprehensive detection of simultaneous genome abnormalities. NGS-based circulating tumor DNA (ctDNA) profiling is a new molecular technique that has demonstrated great potential in the detection and differential diagnosis of cancer relapse. Results: We present a 43-year-old female patient with synchronous breast and rectal cancer that was surgically removed 2 years prior. During regular follow-up, elevated carcinoembryonic antigen (CEA) levels were detected. ctDNA profiling revealed multiple somatic mutations that were identical to those found in rectal cancer samples. Thus, we suspected relapse of rectal cancer. Positron emission tomography-computed tomography (PET-CT) and pathogenic analysis confirmed lung metastasis of rectal cancer. Conclusions: This case demonstrated the utility of ctDNA profiling in the detection and differential diagnosis of cancer relapse in a patient with synchronous breast and rectal cancer.

High-Resolution Valley Spectroscopy of Si Quantum Dots

We study an accumulation mode Si/SiGe double quantum dot (DQD) containing a single electron that is dipole coupled to microwave photons in a superconducting cavity. Measurements of the cavity transmission reveal dispersive features due to the DQD valley states in Si. The occupation of the valley states can be increased by raising the temperature or applying a finite source-drain bias across the DQD, resulting in an increased signal. Using the cavity input-output theory and a four-level model of the DQD, it is possible to efficiently extract valley splittings and the inter- and intravalley tunnel couplings.

Threshold Dynamics of a Semiconductor Single Atom Maser

We demonstrate a single atom maser consisting of a semiconductor double quantum dot (DQD) that is embedded in a high-quality-factor microwave cavity. A finite bias drives the DQD out of equilibrium, resulting in sequential single electron tunneling and masing. We develop a dynamic tuning protocol that allows us to controllably increase the time-averaged repumping rate of the DQD at a fixed level detuning, and quantitatively study the transition through the masing threshold. We further examine the crossover from incoherent to coherent emission by measuring the photon statistics across the masing transition. The observed threshold behavior is in agreement with an existing single atom maser theory when small corrections from lead emission are taken into account.

High-dose dexamethasone or all-trans-retinoic acid restores the balance of macrophages towards M2 in immune thrombocytopenia

Essentials M1/M2 imbalance is involved in many autoimmune diseases, and could be restored. The expressions and functions of M1 and M2 were investigated in an in vitro culture system. A preferred M1 polarization is involved in the pathogenesis of immune thrombocytopenia (ITP). High-dose dexamethasone or all-trans-retinoic acid restores M1/M2 balance in ITP patients.

SUMMARY

Background Immune thrombocytopenia (ITP) is an autoimmune disorder. Deficiency of immune tolerance in antigen-presenting cells and cross-communication between antigen-presenting cells and T cells are involved in the pathogenesis of ITP. Macrophages can polarize into proinflammatory M1 or anti-inflammatory M2 phenotypes in response to different environmental stimuli, and have diverse immunologic functions. Objectives To investigate the M1/M2 imbalance in ITP and whether high-dose dexamethasone (HD-DXM) or all-trans-retinoic acid (ATRA) could restore this imbalance. Methods The numbers of M1 and M2 macrophages in the spleens of ITP patients and patients with traumatic spleen rupture were analyzed by immunofluorescence. Monocyte-derived macrophages were cultured and induced with cytokines and drugs. The expression of M1 and M2 markers and functions of M1 and M2 macrophages before and after modulation by HD-DXM or ATRA were evaluated with flow cytometry and ELISA. Results There was preferred M1 polarization in ITP spleens as compared with healthy controls. Monocyte-derived macrophages from ITP patients had increased expression of M1 markers and impaired immunosuppressive functions. Either HD-DXM or ATRA corrected this imbalance by decreasing the expression of M1 markers and increasing the expression of M2 markers. Moreover, HD-DXM-modulated or ATRA-modulated macrophages suppressed both CD4+ and CD8+ T-cell proliferation and expanded CD4+ CD49+ LAG3+ type 1 T-regulatory cells. HD-DXM or ATRA modulated macrophages to shift the T-cell cytokine profile towards Th2. Treating patients with HD-DXM or ATRA revealed that macrophages induced from responders showed a predominant M2-like phenotype and immunosuppressive function. Conclusions Aberrant macrophage polarization is involved in the pathogenesis of ITP. Either HD-DXM or ATRA is able to correct this imbalance.

Preparation of La-modified magnetic composite for enhanced adsorptive removal of tetracycline

Composite adsorbents usually outperform single component adsorbents as they could combine the properties and advantages of each component. In this research, rare earth element Lanthanum was introduced into magnetic substrate by a method of chemical co-precipitation to enhance its adsorption capability. It was found that the La-modified magnetic composite with a presumed La and Fe₃O₄ molar ratio at 1:50 had a better adsorption performance for tetracycline than the magnetic adsorbents at other molar ratios. The La-modified magnetic composite was characterized by scanning electron microscope, X-ray diffractometer, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results showed that the magnetic adsorbent was nano-sized, and the introduction of La did not change the crystal structure of magnetic substrate. The adsorptive removal of tetracycline was favorable at neutral pH conditions. Kinetic experiments indicated that most of the uptake occurred within the initial 120 min. Chemisorption occurred in the process while rate-determining step might be diffusive in nature. An empirical model (Langmuir model) was applied in this paper, and fitting result indicates that the q _max value of the magnetic composite reached as much as 145.9 mg/g for the uptake of tetracycline at 298 K. The above indicates that method of La doping could significantly enhance the adsorption capability of an intentionally designed composite adsorbent.

Effects of JIP3 on epileptic seizures: Evidence from temporal lobe epilepsy patients, kainic-induced acute seizures and pentylenetetrazole-induced kindled seizures

JNK-interacting protein 3 (JIP3), also known as JNK stress-activated protein kinase-associated protein 1 (JSAP1), is a scaffold protein mainly involved in the regulation of the pro-apoptotic signaling cascade mediated by c-Jun N-terminal kinase (JNK). Overexpression of JIP3 in neurons in vitro has been reported to lead to accelerated activation of JNK and enhanced apoptosis response to cellular stress. However, the occurrence and the functional significance of stress-induced modulations of JIP3 levels in vivo remain elusive. In this study, we investigated the expression of JIP3 in temporal lobe epilepsy (TLE) and in a kainic acid (KA)-induced mouse model of epileptic seizures, and determined whether down-regulation of JIP3 can decrease susceptibility to seizures and neuron damage induced by KA. We found that JIP3 was markedly increased in TLE patients and a mouse model of epileptic seizures; mice underexpressing JIP3 through lentivirus bearing LV-Letm1-RNAi showed decreased susceptibility, delayed first seizure and decreased seizure duration response to the epileptogenic properties of KA. Subsequently, a decreased activation of JNK following seizure induction was observed in mice underexpressing JIP3, which also exhibited less neuronal apoptosis in the CA3 region of the hippocampus, as assessed three days after KA administration. We also found that mice underexpressing JIP3 exhibited a delayed pentylenetetrazole (PTZ)-induced kindling seizure process.

Minocycline inhibits brain inflammation and attenuates spontaneous recurrent seizures following pilocarpine-induced status epilepticus

Mounting evidence suggests that brain inflammation mediated by glial cells may contribute to epileptogenesis. Minocycline is a second-generation tetracycline and has potent antiinflammatory effects independent of its antimicrobial action. The present study aimed to investigate whether minocycline could exert antiepileptogenic effects in a rat lithium-pilocarpine model of temporal lobe epilepsy. The temporal patterns of microglial and astrocytic activation were examined in the hippocampal CA1 and the adjacent cortex following pilocarpine-induced status epilepticus (SE). These findings displayed that SE caused acute and persistent activation of microglia and astrocytes. Based on these findings, Minocycline was administered once daily at 45 mg/kg for 14 days following SE. Six weeks after termination of minocycline treatment, spontaneous recurrent seizures (SRS) were recorded by continuous video monitoring. Minocycline inhibited the SE-induced microglial activation and the increased production of interleukin-1β and tumor necrosis factor-α in the hippocampal CA1 and the adjacent cortex, without affecting astrocytic activation. In addition, Minocycline prevented the SE-induced neuronal loss in the brain regions examined. Moreover, minocycline significantly reduced the frequency, duration, and severity of SRS during the two weeks monitoring period. These results demonstrated that minocycline could mitigate SE-induced brain inflammation and might exert disease-modifying effects in an animal model of temporal lobe epilepsy. These findings offer new insights into deciphering the molecular mechanisms of epileptogenesis and exploring a novel therapeutic strategy for prevention of epilepsy.

Molecular characterization, immune responsive expression and functional analysis of QM, a putative tumor suppressor gene from the Pacific white shrimp, Litopenaeus vannamei

The QM, firstly identified as a putative tumor suppressor gene from human, has been confirmed to possess varieties of functions in a range of organisms. In the present study, the cDNA that encodes a 220-amino-acid QM protein with calculated molecular mass of 25.5 kDa and isoelectric point of 10.07 was characterized from the Pacific white shrimp Litopenaeus vannamei. Analysis of the deduced amino acid sequence of LvQM revealed that it contained a series of conserved functional motifs. Quantitative real-time PCR (qRT-PCR) results showed that the transcript of LvQM was extensively distributed in the tissues under investigation and most highly expressed in gill. After challenged with Vibrio anguillarum, the LvQM transcripts were significantly increased (P < 0.05) both in hepatopancreas and hemocytes in the early experimental phase. When LvQM was knocked down by RNA interference (RNAi), the transcript of prophenoloxidase (proPO) and the phenoloxidase activity (PO) in shrimp hemolymph were dramatically decreased, while the mortality was significantly increased. Furthermore, the recombinant LvQM protein (rLvQM) was successfully expressed in Escherichia coli BL21 (DE3)-pLysS. Injecting the purified rLvQM mixed with V. anguillarum markedly increased the clearance rate of bacteria and PO activity in the shrimp hemolymph. Hence, we conclude that LvQM was involved in the host defense of L. vannamei, probably as a positive regulator to phenoloxidase activity.

p53 is involved in shrimp survival via its regulation roles on MnSOD and GPx in response to acute environmental stresses

The tumor suppressor gene p53 plays a critical role in safeguarding the integrity of genome in mammalian cells. It acts as a sequence-specific transcription factor. Once activated by a variety of cellular stresses, p53 transactivates downstream target genes, through which it regulates cell cycle and apoptosis. However, little is known about p53 as well as its downstream target genes in invertebrates. A full length cDNA that encodes a 453-amino-acid p53 protein (Lvp53) was characterized in the Pacific white shrimp (Litopenaeus vannamei) to explore the potential relationships between p53 and two antioxidant enzyme genes: Mn-superoxide dismutase (MnSOD) and glutathione peroxidase (GPx) in eliminating cell stresses in L. vannamei. Sequence analysis revealed a close phylogenetic relationship between Lvp53 and that of Marsupenaeus japonicus, and a high degree of conservation in critical amino acids residues is involved in DNA and zinc binding among species. Quantitative real-time PCR showed that Lvp53 was expressed with varied levels in all the 11 tissues under investigation. In response to acute pH challenge, the relative expression of Lvp53 was induced in a pH- and time-dependent manner, with the peak observed at pH 6.1 and after 24 h of treatment, in which condition, both the relative mRNA expressions and the enzymatic activities of LvMnSOD and LvGPx were increased correspondingly. In response to acute cadmium (Cd) exposure, the relative expression of Lvp53 was upregulated in a time- and concentration-dependent manner, with the maximum detected at Cd 6.6 μM and after 48 h of exposure, in which case, both the transcripts and the enzymatic activities of LvMnSOD and LvGPx were also induced. After Lvp53 transcripts were declined by double-strand RNA injection, the relative mRNA expressions of LvMnSOD and LvGPx were decreased correspondingly. Meanwhile, pH 6.1 or 6.6 μM Cd could not induce the transcripts or the enzymatic activities of LvMnSOD or LvGPx any more in Lvp53-silenced shrimp, but increased shrimp mortalities. These results indicated the involvement of Lvp53, LvMnSOD and LvGPx in mediating cell stress caused by suboptimal pH and elevated levels of Cd in L. vannamei, and that the expressions of LvMnSOD and LvGPx were positively regulated by Lvp53, which is a potential mechanism for shrimp to survive the oxidative stress that occurs during short-term exposure to Cd or challenge with acidic pH. This finding will contribute to better understanding of p53 signaling pathways and redox regulation in invertebrate organisms.

Identification and functional studies of Akirin, a potential positive nuclear factor of NF-κB signaling pathways in the Pacific white shrimp, Litopenaeus vannamei

As conserved nuclear factors, Akirins play critical roles in regulating antimicrobial peptides (AMPs) transcription downstream of NF-κB dependent signaling pathways in insects and mammals. However, no any functional studies was reported in penaeid shrimp. The identification and functional analysis of Akirin in the Pacific white shrimp, Litopenaeus vannamei were made in this research. The 833 nucleotides cDNA of Litopenaeus vannamei Akirin (LvAkirin) was obtained with an open reading frame of 639 bp, which encodes a putative protein of 212 amino acids. The molecular weight of LvAkirin is about 23.7 kDa with theoretical pI of 9.05. Two predicted nuclear localization signals (NLSs) were found and amino acid sequence alignments showed that Akirins are highly conserved between insects and mammals. The constitutive expression of LvAkirin mRNA was confirmed in all the examined tissues and high level appeared in testis followed by hemocytes and gill. LvAkirin mRNA was strongly induced in response to Vibrio parahaemolyticus infection. Silencing LvAkirin by dsRNA significantly reduced the expression of NF-κB dependent anti-lipopolysaccharide factor, crustin and penaeidin3a as well as transcription factors, Dorsal and Relish post Vibrio anguillarum (V. anguillarum) and Micrococcus lysodeikticus (M. lysodeikticus) challenge. Antibacterial activities of shrimp plasma was analyzed and high cumulative mortality was found in LvAkirin-silenced shrimps post bacteria challenge. Hence, we proposed LvAkirin might function as a positive nuclear factor of NF-κB dependent signaling pathways in shrimp innate immunity.

Molecular characterization of a p38 MAPK from Litopenaeus vannamei and its expression during the molt cycle and following pathogen infection

The p38 mitogen-activated protein kinase (MAPK), a serine/threonine-specific protein kinase, has been reported to be involved in innate immunity, development and muscle differentiation. To explore the function of p38 in shrimp, partial cDNA sequence of p38 in Litopenaeus vannamei (designated as Lv-p38) was characterized and the expression of Lv-p38 in hepatopancreas of the shrimp after being infected with Vibrio parahaemolyticus and in muscle of the shrimp at different molt stages was detected by quantitative RT-PCR in this study. The results showed that the open reading frame of Lv-p38 was 1098 bp and encoded a protein of 365 amino acids. The protein of Lv-p38 which showed close phylogenetic relationship to Marsupenaeus japonicus p38 had a conserved TGY motif and serine/threonine protein kinase (S_TKc) domain. The expression of Lv-p38 was detected in all tested tissues, especially in the hepatopancreas and muscle. The expression of Lv-p38 in the hepatopancreas was different from that of the control at the 24th hour after the injection of V. parahaemolyticus and in the muscle significantly increased at stage C but decreased at other stages during molt, illustrating that Lv-p38 could be involved in pathogen infection and the molt cycle of shrimp. In conclusion, we identified Lv-p38 and studied its role in pathogen infection and molting, which might facilitate our understanding of the function of p38 in innate immunity and growth during molt of shrimp.

Genome-wide transcriptional analysis of differentially expressed genes in flagellin-pretreated mouse corneal epithelial cells in response to Pseudomonas aeruginosa: involvement of S100A8/A9

We previously showed that pre-exposure of the cornea to Toll-like receptor 5 ligand flagellin induces profound mucosal innate protection against infections by modifying gene expression. Taking advantage of easily procurable epithelial cell population, this study is the first report to use genome-wide cDNA microarray approach to document genes associated with flagellin-induced protection against Pseudomonas aeruginosa in corneal epithelial cells (CECs). Infection altered the expression of 675 genes (497 up and 178 down), while flagellin pretreatment followed by infection resulted in a great increase in 890 gene upregulated and 37 genes downregulated. Comparing these two groups showed 209 differentially expressed genes (157 up, 52 down). Notably, among 114 genes categorized as defense related, S100A8/A9 are the two most highly induced genes by flagellin, and their expression in the corneal was confirmed by realtime PCR and immunohistochemistry. Neutralization of S100A8 and, to a less extent, A9, resulted in significantly increased bacterial burden and severe keratitis. Collectively, our study identifies many differentially expressed genes by flagellin in CECs in response to Pseudomonas. These novel gene expression signatures provide new insights and clues into the nature of protective mechanisms established by flagellin and new therapeutic targets for reducing inflammation and for controlling microbial infection.

Fine mapping of qhir1 influencing in vivo haploid induction in maize

Production of haploids by the in vivo haploid induction method has now become routine for generating new inbred lines in maize. In previous studies, a major quantitative trait locus (QTL) (qhir1) located in bin 1.04 was detected, explaining up to 66 % of the genotypic variance for haploid induction rate (HIR). Our objectives were to (1) fine-map qhir1 and (2) identify closely linked markers useful for marker-assisted breeding of new inducers. For this purpose, we screened a mapping population of 14,375 F2 plants produced from a cross between haploid inducer UH400 and non-inducer line 1680 to identify recombinants. Based on sequence information from the B73 reference genome, markers polymorphic between the two parents were developed to conduct fine mapping with these recombinants. A progeny test mapping strategy was applied to accurately determine the HIR of the 14 recombinants identified. Furthermore, F3 progeny of recombinant F2 plants were genotyped and in parallel evaluated for HIR. We corroborated earlier studies in that qhir1 has both a significantly positive effect on HIR but also a strong selective disadvantage, as indicated by significant segregation distortion. Altogether, we were able to narrow down the qhir1 locus to a 243 kb region flanked by markers X291 and X263.

Multispecies coexistence of trees in tropical forests: spatial signals of topographic niche differentiation increase with environmental heterogeneity

Neutral and niche theories give contrasting explanations for the maintenance of tropical tree species diversity. Both have some empirical support, but methods to disentangle their effects have not yet been developed. We applied a statistical measure of spatial structure to data from 14 large tropical forest plots to test a prediction of niche theory that is incompatible with neutral theory: that species in heterogeneous environments should separate out in space according to their niche preferences. We chose plots across a range of topographic heterogeneity, and tested whether pairwise spatial associations among species were more variable in more heterogeneous sites. We found strong support for this prediction, based on a strong positive relationship between variance in the spatial structure of species pairs and topographic heterogeneity across sites. We interpret this pattern as evidence of pervasive niche differentiation, which increases in importance with increasing environmental heterogeneity.