[Spatial Distribution of Aerobic Bacteria, Sources and Risks of Nitrogen and Phosphorus in Taihu Lake Sediments].

The release of nitrogen and phosphorus from sediments into lake water will exacerbate the eutrophication of lakes and endanger ecological safety and human health. Microorganisms are indispensable in nitrogen and phosphorus conversion, and accurate analysis of the distribution characteristics and sources of nitrogen and phosphorus in sediments as well as their relationship with microorganisms is an important prerequisite for lake eutrophication control. Taking Taihu Lake as the study area, 30 surface sediment samples were collected, and the grain size, pH, organic matter (OM), dissolved organic carbon (DOC), total phosphorus (TP), total nitrogen (TN), nitrate nitrogen (NO3--N), and dissolved organic nitrogen (DON) along with some other index contents were measured and analyzed; accordingly, spatial distribution characteristics were analyzed. While using nutrient agar (NA), the number of aerobic bacteria (AB) was determined by plate counting in the medium. Combined with principal component analysis (PCA) and Pearson correlation analysis, the spatial distribution characteristics and sources of sediments and AB in Taihu Lake were explored. The characteristics of sediment pollution in Taihu Lake were studied using the comprehensive pollution index and the organic pollution index methods. The results revealed that the average sediment indicators of the surface layer of Taihu Lake were as follows:AB was 9.25×104 CFU·g-1, average particle size (MZ) was 17.59 µm, pH was 7.62, ω(OM) was 15.05 g·kg-1, ω(DOC) was 71.60 mg·kg-1, ω(TP) was 598.13 mg·kg-1, ω(TN) was 1113.92 mg·kg-1, ω(NO3--N) was 3.22 mg·kg-1, and ω(DON) was 22.60 mg·kg-1. The comprehensive pollution index (FF) showed that 13% of the Taihu Lake was moderately polluted, while 87% was heavily polluted. Excluding the area in the center of the lake, the southern lake area, and some lakes in the western part of the East Taihu Lake, TN in the rest of the area was moderately and severely polluted. In addition to the heavy pollution of Zhushan Bay, the TP in Taihu Lake was generally at light and moderate pollution. The organic pollution index (OI) showed that the organic pollution of the sediments of Taihu Lake was relatively light, majorly caused by organic nitrogen (ON) pollution. DOC, DON, TN, and OM in Taihu Lake were primarily derived from the influence of aquatic plants, and TP And AB were primarily derived from the influence of the external input of rivers. This research will provide theoretical support for lake eutrophication treatment and also provide new ideas for further analysis of AB to remove nitrogen and phosphorus pollution from sediments.

[Occurrence Characteristics of Microplastics in Baiyangdian Lake Water and Sediments].

In order to explore the occurrence characteristics of microplastics in the freshwater environment of Baiyangdian Lake in China, ten overlying water samples and ten sediment samples were collected in Baiyangdian Lake of Hebei Province in October 2021, and the abundance distribution, shape, particle size, and polymer type of microplastics in the samples were identified using laboratory pretreatment, microscope observation, and laser infrared spectroscopy. The sedimentation law of microplastics at the overlying water-sediment interface was studied using the Stokes sedimentation formula, and their pollution characteristics and potential sources were analyzed. The abundances of microplastics in the overlying water and sediments in Baiyangdian Lake ranged from 474-19382 n·m-3 and 95.3-29542.5 n·kg-1, respectively, with an average value of 6255.4 n·m-3 and 11088 n·kg-1. The main polymer of the microplastics in the overlying water was polyethylene terephthalate[PET, (17.20±0.26)%], and the microplastics in the sediments were mainly chlorinated polyethylene[CPE, (46.11±1.30)%]. The sedimentation velocities of microplastics in the sedimentation zone ranged from 0.0793-111.7547 mm·s-1. The particles with larger particle size had higher sedimentation velocity and easily settled and remained in the sediments. The main sources of microplastic pollution in the study area were the discharge of textile fibers from washing wastewater and the wear and tear of ship paint, ship rubber, and building materials.

Establishment of Transgenic Mouse Leukemia Cell Lines Expressing Human CD4/CCR5/CyclinT1 Infected with HIV-1.

PURPOSE: Establishing a cross-species animal model of human immunodeficiency virus (HIV) infection is crucial for the study of HIV/acquired immunodeficiency syndrome (AIDS). However, due to the species-specific characteristics of HIV-1, the virus can only infect directly humans and a small number of non-human primates. It cannot directly infect mouse cells across species. METHODS: A mouse leukemia cell line with high CD4 (clusters of differentiation 4)/CCR5 (CC-chemokine receptor 5)/CyclinT1 expression was constructed in this study. First, CD4/CCR5/CyclinT1 lentiviral vector was used to infect a murine leukemia cell line L1210 to express the receptor CD4, co-receptor CCR5 and tat protein driving factor CyclinT1, which are required to infect L1210 cells with HIV-1. RESULTS: The results of sequencing identification and fluorescence expression showed that the plasmid expressing CD4, CCR5, and CyclinT1 vector was successfully constructed and wrapped as the lentiviral vector. Moreover, it was observed that CD4, CCR5, and CyclinT1 proteins were highly expressed in mouse leukemia cells L1210 compared to empty lentiviral vector-transfected cells. Next, viral entry and replication were demonstrated when HIV-1 RNA was detected in body cells and cultured supernatants. Transgenic mice cells L1210 showed significantly greater content of HIV-1 RNA compared to control L1210 cells. Finally, CEMx174 was infected with cell culture supernatants to clarify that the progeny virus is an active virus with infection ability. HIV-1 RNA was highly expressed in CEMx174 cells. CONCLUSIONS: This study made the foundation for future studies evaluating HIV-1 cross-species infection in a murine animal model. The results provided new direction for studies investigating the development of vaccines, antiviral drugs screening, and HIV/AIDS pathogenesis.

A circuit from the ventral subiculum to anterior hypothalamic nucleus GABAergic neurons essential for anxiety-like behavioral avoidance.

Behavioral observations suggest a connection between anxiety and predator defense, but the underlying neural mechanisms remain unclear. Here we examine the role of the anterior hypothalamic nucleus (AHN), a node in the predator defense network, in anxiety-like behaviors. By in vivo recordings in male mice, we find that activity of AHN GABAergic (AHNVgat+) neurons shows individually stable increases when animals approach unfamiliar objects in an open field (OF) or when they explore the open-arm of an elevated plus-maze (EPM). Moreover, object-evoked AHN activity overlap with predator cue responses and correlate with the object and open-arm avoidance. Crucially, exploration-triggered optogenetic inhibition of AHNVgat+ neurons reduces object and open-arm avoidance. Furthermore, retrograde viral tracing identifies the ventral subiculum (vSub) of the hippocampal formation as a significant input to AHNVgat+ neurons in driving avoidance behaviors in anxiogenic situations. Thus, convergent activation of AHNVgat+ neurons serves as a shared mechanism between anxiety and predator defense to promote behavioral avoidance.

Connecting macroscopic diffusion metrics of cardiac diffusion tensor imaging and microscopic myocardial structures based on simulation.

To investigate the relationship between microscopic myocardial structures and macroscopic measurements of diffusion tensor imaging (DTI), we proposed a cardiac DTI simulation method using the Bloch equation and the Monte Carlo random walk in a realistic myocardium model reconstructed from polarized light imaging (PLI) data of the entire human heart. To obtain a realistic simulation, with the constraints of prior knowledge pertaining to the maturational change of the myocardium structure, appropriate microstructure modeling parameters were iteratively determined by matching DTI simulations and real acquisitions of the same hearts in terms of helix angle, fractional anisotropy (FA) and mean diffusivity (MD) maps. Once a realistic simulation was obtained, we varied the extra-cellular volume (ECV) ratio, myocyte orientation heterogeneity and myocyte size, and explored the effects of microscopic changes in tissue structure on macroscopic diffusion metrics. The experimental results demonstrated the feasibility of simulating the DTI of the whole heart using PLI measurements. When varying ECV from 15% to 55%, mean FA decreased from 0.55 to 0.26, axial diffusivity increased by 0.6 µm2/ms, and radial diffusivity increased by 0.7 µm2/ms. When orientation heterogeneity was varied from 0 to 20∘, mean FA decreased from 0.4 to 0.3, axial diffusivity decreased by 0.08 µm2/ms, and radial diffusivity increased by 0.03 µm2/ms. When mean diameter of myocytes was varied from 6 µm to 10 µm, FA decreased from 0.67 to 0.46, axial and radial diffusivities increased by 0.05 and 0.2 µm2/ms, respectively.

Non-Noble-Metal Metal-Organic-Framework-Catalyzed Carboxylative Cyclization of Propargylic Amines with Atmospheric Carbon Dioxide under Ambient Conditions.

The coupling reaction of propargylic amines and carbon dioxide (CO2) to synthesize 2-oxazolidinones is an important reaction in industrial production, and yet harsh reaction conditions and noble-metal catalysts are often required to achieve high product yields. Herein, one novel noble-metal-free three-dimensional framework, [Mg3Cu2I2(IN)4(HCOO)2(DEF)4]n (1), assembled by magnesium and copper clusters was synthesized and applied to this reaction. Compound 1 displays excellent solvent stability. Importantly, 1, acting as heterogeneous catalyst, can highly catalyze the cyclization of propargylic amines with CO2 under atmospheric pressure at room temperature, which can be recycled at least five times without an obvious decrease of the catalytic activity. NMR spectroscopy, coupled with 13C-isotope- and deuterium-labeling experiments, clearly clarifies the mechanism of this catalytic system: CO2 was successfully captured and converted to the product of 2-oxazolidinones, the C≡C bond of propargylic amines can be effectively activated by 1, and proton transfer was involved in the reaction process. Density functional theory calculations are further conducted to uncover the reaction path and the crucial role of compound 1 during the reaction.

Association between Toxoplasma gondii types and outcomes of human infection: A meta-analysis.

The virulence and pathogenicity of various types of Toxoplasma gondii differ considerably in mice. Recent studies have claimed that similar phenomenon was observed in humans, but no relevant studies have been performed to validate this finding. In addition, reports showing association between a given T. gondii type and outcomes of human infection yielded conflicting results. To provide a more precise estimation of the association and a more reliable conclusion on this subject, we performed this meta-analysis. Relevant literatures were identified in multiple databases and selected based on strict screening. T. gondii-type proportions among different severities of infection were calculated and compared using Fisher's exact test. Pooled odds ratios (OR) were calculated. Our results showed that the difference among T. gondii-type proportions was significant (p < 0.0001). In addition, significant associations were detected between Type I strains infection and congenital toxoplasmosis (OR: 1.91, p = 0.0009), Type III strains infection and pulmonary toxoplasmosis (OR: 5.15, p = 0.04). In our subgroup analysis, Type I strains were significantly associated with cerebral toxoplasmosis in offspring (OR: 1.81, p = 0.02). This result indicated that different types of T. gondii exhibited different virulence and caused different outcomes in humans.