A certain number of epithelial cells in intestinal crypts are DNA damage resistant and contribute to regeneration. However, the cellular mechanism underlying intestinal regeneration remains unclear. ...Using lineage tracing, we show that cells marked by an Msi1 reporter (Msi1+) are right above Lgr5high cells in intestinal crypts and exhibit DNA damage resistance. Single-cell RNA sequencing reveals that the Msi1+ cells are heterogeneous with the majority being intestinal stem cells (ISCs). The DNA damage-resistant subpopulation of Msi1+ cells is characterized by low-to-negative Lgr5 expression and is more rapidly cycling than Lgr5high radiosensitive crypt base columnar stem cells (CBCs). This enables an efficient repopulation of the intestinal epithelium at early stage when Lgr5high cells are not emerging. Furthermore, relative to CBCs, Msi1+ cells preferentially produce Paneth cells during homeostasis and upon radiation repair. Together, we demonstrate that the DNA damage-resistant Msi1+ cells are cycling ISCs that maintain and regenerate the intestinal epithelium.
Display omitted
•Cycling Msi1+ ISCs in the intestinal crypt are DNA damage resistant•Msi1+ ISCs enable fast intestinal repair ahead of Lgr5high CBCs•Paneth cells preferentially arise from Msi1+ ISCs during homeostasis and repair
Quiescent reserve stem cells in the intestine are thought to activate following irradiation to restore the depleted Lgr5high CBCs. Now, Sheng et al. demonstrate that cycling Msi1+ cells represent DNA damage-resistant ISCs that support efficient repopulation of the intestinal epithelium at the early stage of post-radiation repair, ahead of Lgr5high CBCs.
This paper presents a feasible road to achieving green development through the e-commerce model. We employ the data of 230 cities data in China from 2003 to 2017 as a research sample and use the ...Multi-period DID method to test the policy shock of National E-commerce Demonstration Cities (NEDC) pilots on the green total factor productivity (GTFP). The basic results show that urban GTFP increases by about 1.24% on average after becoming pilot cities, and NEDC policy has promoted the improvement of urban GTFP. We adopt different methods to test the robustness of the basic results, and all tests show that basic results are extremely robust. Moreover, NEDC policy plays a more effective role in the growth of urban GTFP in the mid-western cities and resource-based cities. The industrial structure upgrading effect, unproductive costs reduction effect, and green innovation motivating effect are the key mechanisms for NEDC policy to affect urban GTFP. Under the context of the information technology era, this study provides new evidence for the relationship between e-commerce and green development, and also gives policy guidance for other countries who are seeking the energy-saving and emission-reduction measures.
•We study the impact of National E-commerce Demonstration Cities (NEDC) policy on green total factor productivity (GTFP).•The NEDC policy has significantly and robustly promoted the improvement of urban GTFP.•Some historical variables are used as instrument variables to solve endogenous problems.•There are three mechanisms: industrial structure upgrading, unproductive costs reduction, and green innovation motivating.•The NEDC policy plays a more effective role in the growth of urban GTFP in the mid-western cities and resource-based cities.
Recently, higher-order topological phases that do not obey the usual bulk-edge correspondence principle have been introduced in electronic insulators and brought into classical systems, featuring ...in-gap corner or hinge states. In this Letter, using near-field scanning measurements, we show the direct observation of corner states in second-order topological photonic crystal slabs consisting of periodic dielectric rods on a perfect electric conductor. Based on the generalized two-dimensional Su-Schrieffer-Heeger model, we show that the emergence of corner states roots in the nonzero edge dipolar polarization instead of the nonzero bulk quadrupole polarization. We demonstrate the topological transition of two-dimensional Zak phases of photonic crystal slabs by tuning intracell distances between two neighboring rods. We also directly observe in-gap one-dimensional edge states and zero-dimensional corner states in the microwave regime. Our work presents that the photonic crystal slab is a powerful platform to directly observe topological states and paves the way to study higher-order photonic topological insulators.
To battle adverse internal and external conditions and maintain homeostasis, diploid organisms employ various cellular processes, such as proliferation and apoptosis. In some tissues, an alternative ...mechanism, endoreplication, is employed toward similar goals. Endoreplication is an evolutionarily conserved cell cycle program during which cells replicate their genomes without division, resulting in polyploid cells. Importantly, endoreplication is reported to be indispensable for normal development and organ formation across various organisms, from fungi to humans. In recent years, more attention has been drawn to delineating its connections to wound healing and tumorigenesis. In this Review, we discuss mechanisms of endoreplication and polyploidization, their essential and positive roles in normal development and tissue homeostasis, and the relationship between polyploidy and cancer.
As an alternative cell cycle program, endoreplication is crucial during development. Polyploid cells assume various pivotal functions in metazoans.
Besides its significant role in development, endoreplication is induced by various signaling pathways to maintain homeostasis and tissue integrity, and to assist the wound healing and tissue repair processes.
Polyploidy and aneuploidy are widespread across different types of cancer, contributing to cancer progression, surveillance escape, and relapse.
Polyploid giant cancer cells (PGCCs) possess stem cell characteristics, and can differentiate into three germ layers in vitro. PGCCs can form tumors through asymmetric budding or bursting.
•Strain DM02 efficiently removes TAN, nitrate, nitrite under high oxygen environment.•Diverse organic carbon can be used by strain DM02 for NO3−-N removal (>95%).•NO3− and NO2− removal efficiency was ...linearly related to C/N ratio (range 0–10).•The contribution of N assimilation for N removal increased linearly with C/N ratio.•Immobilized technology has been used for real aquaculture wastewater treatment.
A bacterial strain was isolated and identified as Pseudomonas sp. DM02 from an aquaculture system. Strain DM02 showed efficient heterotrophic nitrification-aerobic denitrification capability. Total ammonia nitrogen (TAN, 10 mg/L) could be completely removed by strain DM02 within 12 h under low nutrient condition. Nitrogen mass balance indicated that 70.8% of the initial TAN was translated into gaseous nitrogen and 28.1% was converted into intracellular nitrogen. Various carbon sources can be used for nitrate removal (>95% within 28 h). The optimal conditions for TAN, nitrate and nitrite removal were pH 7 with carbon/nitrogen (C/N) ratios of 8, 12 and 12, respectively. The napA, nirK, and nosZ functional genes were successful amplified from strain DM02. Both bioaugmentation and immobilized technology of strain DM02 present ability (>88%) for continuous treatment of real aquaculture wastewater. This research indicated a great potential for practical application of Pseudomonas sp. DM02 in aquaculture wastewater treatment.
Artificial steel slag aggregates were prepared via accelerated carbonation with the assistance of EDTA. The influences of EDTA on the CO2 uptake, microstructure, and properties of the carbonated ...steel slag aggregates as well as the performance of concrete were investigated. With the addition of EDTA, the carbonation of steel slag aggregates was enhanced, yielding increases in CO2 uptake, quantity of formed CaCO3 and bulk density whereas reduction in the crushing value. Moreover, EDTA improved the volume stability of the steel slag aggregate. The EDTA played a role as a catalyst in the process of steel slag carbonation, which chelated the calcium leached from steel slag and hence accelerated the calcium leaching. This hence increased the carbonation efficiency and carbonation degree of steel slag. Concretes cast with the steel slag aggregates modified by EDTA gained higher compressive strengths and more stable volumes than that of concretes cast with the steel slag aggregates without EDTA.
The HIV/AIDS epidemic continues to threaten the health and wellbeing of millions in the United States and worldwide. Syndemic theory suggests that HIV/AIDS can cooccur with other afflictions. As ...close to 20% of US adults live with a mental health condition, it is critical to understand the correlation between HIV risk behaviors and mental health needs, as well as protective factors such as social support in intervening the association between mental distress and HIV risk behaviors. Furthermore, as past research has shown mixed results concerning the function of social support on HIV risks by gender, it is important to conduct a gender-specific analysis.
To assess the relationship between mental health needs, social support, and HIV risk behaviors, and to assess if social support can be a buffer, weakening the effect of mental health needs on HIV risk, in 2018, we analyzed representative, cross-sectional data from 2016 BRFSS collected from 33,705 individuals from four states in the United States, stratified by gender. Weighted logistic regression analyses, adjusted for age, race, marital status, education, and annual income, assessed the correlation between mental health needs, social support, and HIV risk behaviors. Furthermore, interaction analyses were performed to see if social support modifies the slope of mental health needs as a function of HIV risk behaviors.
For both genders, the odds of participating in HIV risk behaviors increase with mental health needs and decrease with the level of social support. Furthermore, social support mitigates the association between mental health needs and HIV risk behavior involvement for males, as males receiving high level of social support have least odds of HIV risk behaviors relative to males receiving low level of social support. Notably, for females, social support does not serve as a buffer against HIV risk behaviors when their mental health needs increase.
The study contributes to the knowledge base of HIV prevention and highlights the important role of mental health and social support against HIV risk behaviors when developing gender-specific prevention strategies.
In multicellular organisms, tissue integrity and organ size are maintained through removal of aberrant or damaged cells and compensatory proliferation. Little is known, however, about this ...homeostasis system in postmitotic tissues, where tissue-intrinsic genetic programs constrain cell division and new cells no longer arise from stem cells. Here we show that, in postmitotic Drosophila follicular epithelia, aberrant but viable cells are eliminated through cell competition, and the resulting loss of local tissue volume triggers sporadic cellular hypertrophy to repair the tissue. This “compensatory cellular hypertrophy” is implemented by acceleration of the endocycle, a variant cell cycle composed of DNA synthesis and gap phases without mitosis, dependent on activation of the insulin/IGF-like signaling pathway. These results reveal a remarkable homeostatic mechanism in postmitotic epithelia that ensures not only elimination of aberrant cells through cell competition but also proper organ-size control that involves compensatory cellular hypertrophy induced by physical parameters.
•Cell competition occurs in the postmitotic epithelium•Compensatory cellular hypertrophy (CCH) as a tissue repair mechanism•CCH is implemented by acceleration of the endoreplication cycle•Loss of local tissue volume triggers sporadic epithelial CCH over a long range
Tamori and Deng show that cell competition occurs in postmitotic epithelia to remove aberrant cells. Their studies also reveal that a loss of local tissue volume resulting from cell death or reduced cell size triggers compensatory cellular hypertrophy sporadically throughout the epithelium to ensure tissue homeostasis.
Oogenesis is a complex developmental process that involves spatiotemporally regulated coordination between the germline and supporting, somatic cell populations. This process has been modeled ...extensively using the Drosophila ovary. Although different ovarian cell types have been identified through traditional means, the large-scale expression profiles underlying each cell type remain unknown. Using single-cell RNA sequencing technology, we have built a transcriptomic data set for the adult Drosophila ovary and connected tissues. Using this data set, we identified the transcriptional trajectory of the entire follicle-cell population over the course of their development from stem cells to the oogenesis-to-ovulation transition. We further identify expression patterns during essential developmental events that take place in somatic and germline cell types such as differentiation, cell-cycle switching, migration, symmetry breaking, nurse-cell engulfment, egg-shell formation, and corpus luteum signaling. Extensive experimental validation of unique expression patterns in both ovarian and nearby, nonovarian cells also led to the identification of many new cell type-and stage-specific markers. The inclusion of several nearby tissue types in this data set also led to our identification of functional convergence in expression between distantly related cell types such as the immune-related genes that were similarly expressed in immune cells (hemocytes) and ovarian somatic cells (stretched cells) during their brief phagocytic role in nurse-cell engulfment. Taken together, these findings provide new insight into the temporal regulation of genes in a cell-type specific manner during oogenesis and begin to reveal the relatedness in expression between cell and tissues types.
Uniquely, China employs MgO already contained in cement clinker or as an expansive additive to compensate for the thermal shrinkage of mass concrete, particularly dam concrete, with almost 40years' ...experience in both research activities and industrial applications. Compensating shrinkage with expansion produced by MgO has been proved to effectively prevent thermal cracking of mass concrete, and reduce the cost of temperature control measures and speed up the construction process. Moreover, the expansion properties of MgO could be designed flexibly, through adjusting its microstructure by changing the calcination conditions (calcining temperature and residence time). The collective knowledge and experience of MgO expansive cement and concrete is worthy of sharing with relevant engineers and researchers globally but dissemination has been hindered as most of the relevant literature is published in Chinese. This paper reviews the history, state-of-the-art progress and future research needs in the field of MgO expansive cement and concrete.
•Review on near 40years' research history of MgO expansive cement and concrete•Review on the state-of-the-art progress in the field of MgO cement and concrete•Review on future work needs for extending application of MgO cement and concrete•Review on production, property design, and application of MgO in cement materials•Review on mechanical performance, durability, and soundness of MgO concrete
PDF
