Identification and characterization of the TetR family transcriptional regulator NffT in Rhizobium johnstonii.

Symbiotic nitrogen fixation (SNF) by rhizobia is not only the main natural bionitrogen-source for organisms but also a green process leveraged to increase the fertility of soil for agricultural production. However, an insufficient understanding of the regulatory mechanism of SNF hinders its practical application. During SNF, nifA-fixA signaling is essential for the biosynthesis of nitrogenases and electron transfer chain proteins. In the present study, the TetR regulator NffT, whose mutation increased fixA expression, was discovered through a fixA-promoter-ß-glucuronidase fusion assay performed with Rhizobium johnstonii. Real-time quantitative PCR analysis showed that nffT deletion increased the expression of symbiotic genes including nifA and fixA in nifA-fixA signaling, and fixL, fixK, fnrN, and fixN9 in fixL-fixN signaling. nffT overexpression resulted in disordered nodules and reduced nitrogen-fixing efficiency. Electrophoretic mobility shift assays revealed that NffT directly regulated the transcription of RL0091-93, which encode an ATP-binding ABC transporter predicted to be involved in carbohydrate transport. Purified His-tagged NffT bound to a 68 bp DNA sequence located -32 to -99 bp upstream of RL0091-93 and NffT deletion significantly increased the expression of RL0091-93. nffT-promoter-ß-glucuronidase fusion assay indicated that nffT expression was regulated by the cobNTS genes and cobalamin. Mutations in cobNTS significantly decreased the expression of nffT, and cobalamin restored its expression. These results revealed that NffT affects nodule development and nitrogen-fixing reaction by participating in a complex regulatory network of symbiotic and carbohydrate metabolic genes and, thus, plays a pivotal regulatory role during symbiosis of R. johnstonii-Pisum sativum.IMPORTANCESymbiotic nitrogen fixation (SNF) by rhizobia is a green way to maintain soil fertility without causing environmental pollution or consuming chemical energy. A detailed understanding of the regulatory mechanism of this complex process is essential for promoting sustainable agriculture. In this study, we discovered the TetR-type regulator NffT, which suppressed the expression of fixA in Rhizobium johnstonii. Furthermore, NffT was confirmed to play pleiotropic roles in R. johnstonii-Pisum sativum symbiosis; specifically, it inhibited rhizobial growth, nodule differentiation, and nitrogen-fixing reactions. We revealed that NffT indirectly affected R. johnstonii-P. sativum symbiosis by participating in a complex regulatory network of symbiotic and carbohydrate metabolic genes. Furthermore, cobalamin, a chemical molecule, was reported for the first time to be involved in TetR-type protein transcription during symbiosis. Thus, NffT identification connects SNF regulation with genetic, metabolic, and chemical signals and provides new insights into the complex regulation of SNF, laying an experimental basis for the targeted construction of rhizobial strains with highly efficient nitrogen-fixing capacity.

Defect-induced atomic-level intimate interface of a hollow Ov-CeO2/CdS photocatalyst with a Z-scheme to boost hydrogen evolution.

Construction of Z-scheme heterojunction catalysts with high-speed charge transfer channels for efficient photocatalytic hydrogen production from water splitting is still a challenge. In this work, a lattice-defect-induced atom migration strategy is proposed to construct an intimate interface. The oxygen vacancies of cubic CeO2 obtained from a Cu2O template are used to induce lattice oxygen migration and form SO bonds with CdS to form a close contact heterojunction with a hollow cube. The hydrogen production efficiency reaches ∼12.6 mmol·g-1·h-1 and maintains a high value over 25 h. A series of photocatalytic tests combined with density functional theory (DFT) calculations show that the close contact heterostructure not only promotes the separation/transfer of photogenerated electron-hole pairs but also regulates the intrinsic catalytic activity of the surface. A large number of oxygen vacancies and SO bonds at the interface participate in charge transfer, which accelerates the migration of photogenerated carriers. The hollow structure improves the ability to capture visible light. Therefore, the synthesis strategy proposed in this work, as well as the in-depth discussion of the interface chemical structure and charge transfer mechanism, provides new theoretical support for the further development of photolytic hydrogen evolution catalysts.

ConMLP: MLP-Based Self-Supervised Contrastive Learning for Skeleton Data Analysis and Action Recognition.

Human action recognition has drawn significant attention because of its importance in computer vision-based applications. Action recognition based on skeleton sequences has rapidly advanced in the last decade. Conventional deep learning-based approaches are based on extracting skeleton sequences through convolutional operations. Most of these architectures are implemented by learning spatial and temporal features through multiple streams. These studies have enlightened the action recognition endeavor from various algorithmic angles. However, three common issues are observed: (1) The models are usually complicated; therefore, they have a correspondingly higher computational complexity. (2) For supervised learning models, the reliance on labels during training is always a drawback. (3) Implementing large models is not beneficial to real-time applications. To address the above issues, in this paper, we propose a multi-layer perceptron (MLP)-based self-supervised learning framework with a contrastive learning loss function (ConMLP). ConMLP does not require a massive computational setup; it can effectively reduce the consumption of computational resources. Compared with supervised learning frameworks, ConMLP is friendly to the huge amount of unlabeled training data. In addition, it has low requirements for system configuration and is more conducive to being embedded in real-world applications. Extensive experiments show that ConMLP achieves the top one inference result of 96.9% on the NTU RGB+D dataset. This accuracy is higher than the state-of-the-art self-supervised learning method. Meanwhile, ConMLP is also evaluated in a supervised learning manner, which has achieved comparable performance to the state of the art of recognition accuracy.

[Field control efficacy of 12 insecticides and five species of natural enemies to Thysanogyna limbata]. / 12种杀虫剂及5种天敌昆虫对梧桐木虱的田间控害评价.

Thysanogyna limbata is a pest on the landscape plant Firmiana platanifolia. In this study, we evaluated the control efficacy of twelve insecticides and five common natural enemies to T. limbata. The results showed that the control efficacy of thiamethoxam and imidacloprid to T. limbata was much better than other insecticides. For the three application methods evaluated (spraying, injection, and root-irrigation), the spraying method should be avoided and the injection performed better. If conditions permitted, root-irrigation method could be used as a supplementary method. Among the five natural enemies, Chrysoperla sinica and Lemnia saucia had the best control effect on T. limbata, which could replace insecticide in the long-term control effect. Therefore, C. sinica and L. saucia could be used as safe and environment-friendly pattern to prevent T. limbata in the medium- and long-term in the garden, whereas injection of thiamethoxam and imidacloprid could be used as a short-term and rapid treatment.

A Universal Graphene Quantum Dot Tethering Design Strategy to Synthesize Single-Atom Catalysts.

A general graphene quantum dot-tethering design strategy to synthesize single-atom catalysts (SACs) is presented. The strategy is applicable to different metals (Cr, Mn, Fe, Co, Ni, Cu, and Zn) and supports (0D carbon nanosphere, 1D carbon nanotube, 2D graphene nanosheet, and 3D graphite foam) with the metal loading of 3.0-4.5 wt %. The direct transmission electron microscopy imaging and X-ray absorption spectra analyses confirm the atomic dispersed metal in carbon supports. Our study reveals that the abundant oxygenated groups for complexing metal ions and the rich defective sites for incorporating nitrogen are essential to realize the synthesis of SACs. Furthermore, the carbon nanotube supported Ni SACs exhibits high electrocatalytic activity for CO2 reduction with nearly 100 % CO selectivity. This universal strategy is expected to open up new research avenues to produce SACs for diverse electrocatalytic applications.

Diagnosis of Patent Foramen Ovale: The Combination of Contrast Transcranial Doppler, Contrast Transthoracic Echocardiography, and Contrast Transesophageal Echocardiography.

OBJECTIVES: To access the distinct values of contrast transcranial Doppler (cTCD), contrast transthoracic echocardiography (cTTE), and contrast transesophageal echocardiography (cTEE) in the diagnosis of right-to-left shunt (RLS) due to patent foramen ovale (PFO) and to define the most practical strategy for the diagnosis of PFO. METHODS: 102 patients with a high clinical suspicion for PFO had simultaneous cTCD, cTTE, and cTEE performed. The agitated saline mixed with blood was used to detect right-to-left shunt (RLS). RESULTS: In all 102 patients, the shunt was detected at rest by cTCD in 60.78% of cases, by cTTE in 42.16%, and by cTEE in 47.06%. The positive results of all 3 techniques with Valsalva maneuver (VM) were significantly improved. cTCD showed higher pick-up rate than cTTE (98.04% vs. 89.22%; χ 2 = 12.452, p < 0.05) and the cTEE (98.04% vs. 96.08%; nonsignificant difference) in the diagnosis of PFO. Nevertheless, cTEE, compared with cTTE, underestimated shunting in 44% of patients. The diameter of both PFO entrance and exit was significantly greater in patients with a severe shunt compared with a mild shunt (2.8 ± 1.0 mm vs. 2.0 ± 0.7 mm, t = 3.135, p < 0.05) and the cTEE (98.04% vs. 96.08%; nonsignificant difference) in the diagnosis of PFO. Nevertheless, cTEE, compared with cTTE, underestimated shunting in 44% of patients. The diameter of both PFO entrance and exit was significantly greater in patients with a severe shunt compared with a mild shunt (2.8 ± 1.0 mm vs. 2.0 ± 0.7 mm, t = 3.135, p < 0.05) and the cTEE (98.04% vs. 96.08%; nonsignificant difference) in the diagnosis of PFO. Nevertheless, cTEE, compared with cTTE, underestimated shunting in 44% of patients. The diameter of both PFO entrance and exit was significantly greater in patients with a severe shunt compared with a mild shunt (2.8 ± 1.0 mm vs. 2.0 ± 0.7 mm, t = 3.135, p < 0.05) and the cTEE (98.04% vs. 96.08%; nonsignificant difference) in the diagnosis of PFO. Nevertheless, cTEE, compared with cTTE, underestimated shunting in 44% of patients. The diameter of both PFO entrance and exit was significantly greater in patients with a severe shunt compared with a mild shunt (2.8 ± 1.0 mm vs. 2.0 ± 0.7 mm. CONCLUSIONS: The best method to diagnose PFO should be the combination of cTCD, cTTE, and cTEE. And cTCD should be applied as the first choice for screening RLS. Then, cTTE should be performed to quantify the severity of the shunt. Last but not least, cTEE should be performed to assess the morphologies of PFO when the closure is planned. The study provides for clinicians the most practical strategy for diagnosing PFO in the future. However, further trials with a large sample size are required to confirm this finding.

Understanding the Pathway of Gas Hydrate Formation with Porous Materials for Enhanced Gas Separation.

The reason that the stoichiometry of gas to water in artificial gas hydrates formed on porous materials is much higher than that in nature is still ambiguous. Fortunately, based on our experimental thermodynamic and kinetic study on the gas hydrate formation behavior with classic ordered mesoporous carbon CMK-3 and irregular porous activated carbon combined with density functional theory calculations, we discover a microscopic pathway of the gas hydrate formation on porous materials. Two interesting processes including (I) the replacement of water adsorbed on the carbon surface by gas and (II) further replacement of water in the pore by gas accompanied with the gas condensation in the pore and growth of gas hydrate crystals out of the pore were deduced. As a result, a great enhancement of the selectivity and regeneration for gas separation was achieved by controlling the gas hydrate formation behavior accurately.

Thickness and Ratio of Noncompacted and Compacted Layers of the Left Ventricular Myocardium Evaluated in 56 Normal Fetuses by Two-Dimensional Echocardiography.

The thickness and ratio of noncompacted and compacted layers of the left ventricular (LV) myocardium in the normal fetus were investigated by fetal echocardiography. We aimed to investigate the compaction process of the LV myocardium during the normal gestation period and provide reference for echocardiographic diagnosis of a fetus with ventricular myocardium noncompaction. A total of 56 pregnant women in the gestational period of 23-30 weeks were included. Complete fetal echocardiography was performed with system ultrasonographic examination to exclude congenital heart malformation or extracardiac malformation. All 56 fetuses showed normal development. In the short-axis view of the fetal heart, the LV wall was divided into an upper and lower section at the level of the papillary muscle. Each section was then further divided into four segments, namely, anterior, posterior, lateral, and inferior wall. Thus, the LV wall was divided into eight segments. The thickness of the ventricular noncompacted and compacted layers and the ratio of the ventricular noncompacted to compacted layers of these segments at end-systole were measured and calculated. In echocardiography, the fetal LV myocardium is a two-layered structure: the endocardial noncompact myocardium (NC) with higher echo and the epicardium compact myocardium (C) with lower echo. The noncompacted layer is thinner than the compacted layer in the anterior wall, but thicker than the compacted layers in the posterior, lateral, and inferior wall. With respect to the upper and lower sections of the LV myocardium, the noncompacted layer in each segment of the upper section is thinner than that in each segment of the lower section, whereas the compacted layer of the upper section is thicker than that of the lower section. This study suggests that the densification of the fetal LV myocardium occurs gradually from base to apex and from the anterior to lateral, posterior, and inferior walls. This finding aids in further understanding the process of myocardial densification and provides a diagnostic reference for noncompaction of noncompaction cardiomyopathy (NCCM).

Wall shear stress in portal vein of cirrhotic patients with portal hypertension.

AIM: To investigate wall shear stress (WSS) magnitude and distribution in cirrhotic patients with portal hypertension using computational fluid dynamics. METHODS: Idealized portal vein (PV) system models were reconstructed with different angles of the PV-splenic vein (SV) and superior mesenteric vein (SMV)-SV. Patient-specific models were created according to enhanced computed tomography images. WSS was simulated by using a finite-element analyzer, regarding the blood as a Newtonian fluid and the vessel as a rigid wall. Analysis was carried out to compare the WSS in the portal hypertension group with that in healthy controls. RESULTS: For the idealized models, WSS in the portal hypertension group (0-10 dyn/cm2) was significantly lower than that in the healthy controls (10-20 dyn/cm2), and low WSS area (0-1 dyn/cm2) only occurred in the left wall of the PV in the portal hypertension group. Different angles of PV-SV and SMV-SV had different effects on the magnitude and distribution of WSS, and low WSS area often occurred in smaller PV-SV angle and larger SMV-SV angle. In the patient-specific models, WSS in the cirrhotic patients with portal hypertension (10.13 ± 1.34 dyn/cm2) was also significantly lower than that in the healthy controls (P < 0.05). Low WSS area often occurred in the junction area of SV and SMV into the PV, in the area of the division of PV into left and right PV, and in the outer wall of the curving SV in the control group. In the cirrhotic patients with portal hypertension, the low WSS area extended to wider levels and the magnitude of WSS reached lower levels, thereby being more prone to disturbed flow occurrence. CONCLUSION: Cirrhotic patients with portal hypertension show dramatic hemodynamic changes with lower WSS and greater potential for disturbed flow, representing a possible causative factor of PV thrombosis.

A Comparison of Transthroracic Echocardiograpy and Transcranial Doppler With Contrast Agent for Detection of Patent Foramen Ovale With or Without the Valsalva Maneuver.

Patent foramen ovale (PFO) is a remnant of the fetal circulation exist in 20% of the general population. The purpose of our study was to compare of transthoracic echocardiography (TTE) and contrast-transcranial Doppler sonography (c-TCD) in the diagnosis and quantification of PFO with or without the Valsalva maneuver (VM).We studied 106 patients with a high clinical suspicion for PFO prospectively. Simultaneous c-TCD and TTE were conducted using agitated saline solution to detect right to left shunt (RLS). To classify RLS, mainly PFO, we applied a 4-level visual classification for c-TCD test: no occurrence of micro-embolic signals; grade I, 1 to 10 signals; grade II, 10 to 30 signals but not curtain; and grade III, curtain pattern. We used the number of micro-bubbles appeared in left atrium per frame image to define classification for TTE test: no occurrence of micro-bubbles; grade I, 1 to 10 micro-bubbles; grade II, 10 to 30 micro-bubbles; and grade III, more than 30 micro-bubbles or left atrium nearly filled with micro-bubbles or left atrial opacity. Statistical analyses were performed using SPSS Version 18.0.RLS was detected in 36.0% in c-TCD test and in 46% in TTE test at rest (P = 0.158). And during the VM, RLS was detected in 99.0% in c-TCD test and in 83.0% in TTE test (P < 0.001). Compared with the positive results of c-TCD and TTE at rest, the positive results of them with VM is more higher, respectively (all P < 0.001). The VM obviously increased the number of micro-bubbles shunting.Both c-TCD and TTE should used as initial screening tool for PFO. VM increases the size of shunt. VM resulted in detection of more RLS both in c-TCD and TTE tests.