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1.
Front Pharmacol ; 15: 1415011, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39281283

RESUMO

The objective of this study was to evaluate the clinical effects of perioperative steroid hormone usage in hepatectomy patients through a comprehensive systematic review and meta-analysis. Prospective randomized controlled trials (RCTs) investigating the perioperative use of steroid hormones in hepatectomy patients were systematically searched using various databases, including PubMed, Medline, Embase, the Cochrane Library, the Chinese Biomedical Literature Database, Wanfang Data, and the CNKI database. Two researchers independently screened and extracted data from selected studies. Data analysis was performed using RevMan 5.3 software. The results revealed significantly lower levels of total bilirubin (standard mean difference [SMD] = -0.7; 95% CI: -1.23 to -0.18; and p = 0.009), interleukin-6 (SMD = -1.02; 95% CI: -1.27 to -0.77; and p < 0.001), and C-reactive protein (SMD = -0 .65; 95% CI: -1 .18 to -0.11; and p = 0.02) on postoperative day 1 (POD 1), as well as a reduced incidence of postoperative complications in the steroid group compared to the placebo group. No significant differences were observed between the two groups regarding alanine aminotransferase (ALT) levels, aspartic aminotransferase (AST) levels, or specific complications such as intra-abdominal infection (p = 0.72), wound infection (p = 0.1), pleural effusion (p = 0.43), bile leakage (p = 0.66), and liver failure (p = 0.16). The meta-analysis results indicate that perioperative steroid usage can effectively alleviate liver function impairment and inflammation response following hepatectomy while improving patient prognosis.

2.
Nanomaterials (Basel) ; 14(17)2024 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-39269125

RESUMO

Polymer fibers are considered ideal transmission media for all-optical networks, but their high intrinsic loss significantly limits their practical use. Quantum dot-doped polymer fiber amplifiers are emerging as a promising solution to this issue and are becoming a significant focus of research in both academia and industry. Based on the properties of CdSe/ZnS quantum dots and PMMA material, this study experimentally explores three fabrication methods for CdSe/ZnS quantum dots-doped PMMA fibers: hollow fiber filling, melt-drawing, and melt extrusion. The advantages and disadvantages of each method and key issues in fiber fabrication are analyzed. Utilizing the CdSe/ZnS quantum dots-doped PMMA fibers that were fabricated, we theoretically analyzed the key factors affecting gain performance, including fiber length, quantum dots doping concentration, and signal light intensity. Under the conditions of 1.5 W power and 445 nm laser pumping, a maximum on-off gain of 16.2 dB was experimentally achieved at 635 nm. Additionally, using a white light LED as the signal source, a broadband on-off gain with a bandwidth exceeding 70 nm and a maximum gain of 12.4 dB was observed in the 580-650 nm range. This research will contribute to the development of quantum dots-doped fiber devices and broadband optical communication technology, providing more efficient solutions for future optical communication networks.

3.
ACS Appl Mater Interfaces ; 16(24): 31709-31718, 2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38836706

RESUMO

Air-processed perovskite solar cells (PSCs) with high photoelectric conversion efficiency (PCE) can not only further reduce the production cost but also promote its industrialization. During the preparation of the PSCs in ambient air, the contact of the buried interface not only affects the crystallization of the perovskite film but also affects the interface carrier transport, which is directly related to the performance of the device. Here, we optimize the buried interface by introducing 3-mercaptopropyltrimethoxysilane (MPTMS, (CH3O)3Si(CH2)3SH) on the nickel oxide (NiOx) surface. The crystallization of the perovskite film is improved by enhancing surface hydrophobicity; besides, the SH-based functional group of MPTMS passivates the uncoordinated lead at the interface, which effectively reduces the defects at the bottom interface of perovskite and inhibits the nonradiative recombination at the interface. Moreover, the energy level between the NiOx layer and the perovskite layer is better matched. Based on multiple functions of MPTMS modification, the open circuit voltage of the device is obviously improved, and efficient air-processed methylamine-free (MA-free) PSCs are realized with PCE reaching 21.0%. The device still maintains the initial PCE of 85% after 1000 h aging in the glovebox. This work highlights interface modification in air-processed MA-free PSCs to promote the industrialization of PSCs.

4.
World J Gastrointest Surg ; 16(5): 1371-1376, 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38817278

RESUMO

BACKGROUND: Appendectomy is an acute abdominal surgery that is often accompanied by severe abdominal inflammation. Oral probiotics are one of the postoperative treatments for rapid rehabilitation. However, there is a lack of prospective studies on this topic after appendectomy. AIM: To investigate whether the postoperative probiotics can modulate the inflammatory response and restore intestinal function in patients following appendectomy. METHODS: This was a prospective, randomized trial. A total of 60 emergency patients were randomly divided into a control group (n = 30) and a probiotic group (n = 30). Patients in the control group started to drink some water the first day after surgery, and those in the probiotic group were given water supplemented with Bacillus licheniformis capsules for 5 consecutive days postsurgery. The indices of inflammation and postoperative conditions were recorded, and the data were analyzed with RStudio 4.3.2 software. RESULTS: A total of 60 participants were included. Compared with those in the control group, the C-reactive protein (CRP), interleukin 6 and procalcitonin (PCT) levels were significantly lower in the probiotic group at 2 d after surgery (P = 2.224e-05, P = 0.037, and P = 0.002, respectively, all P < 0.05). This trend persisted at day 5 post-surgery, with CRP and PCT levels remaining significantly lower in the probiotic group (P = 0.001 and P = 0.043, both P < 0.05). Furthermore, probiotics resulted in a shorter time to first flatus and a greater percentage of gram-negative bacilli in the feces (P = 0.035, P = 0.028, both P < 0.05). CONCLUSION: Postoperative oral administration of probiotics may modulate the gut microbiota, benefit the recovery of the early inflammatory response, and subsequently enhance recovery after appendectomy.

5.
Appl Environ Microbiol ; 90(2): e0091423, 2024 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-38265213

RESUMO

Marine macroalgae produce abundant and diverse polysaccharides, which contribute substantially to the organic matter exported to the deep ocean. Microbial degradation of these polysaccharides plays an important role in the turnover of macroalgal biomass. Various members of the Planctomycetes-Verrucomicrobia-Chlamydia (PVC) superphylum are degraders of polysaccharides in widespread anoxic environments. In this study, we isolated a novel anaerobic bacterial strain NLcol2T from microbial mats on the surface of marine sediments offshore Santa Barbara, CA, USA. Based on 16S ribosomal RNA (rRNA) gene and phylogenomic analyses, strain NLcol2T represents a novel species within the Pontiella genus in the Kiritimatiellota phylum (within the PVC superphylum). Strain NLcol2T is able to utilize various monosaccharides, disaccharides, and macroalgal polysaccharides such as agar and É©-carrageenan. A near-complete genome also revealed an extensive metabolic capacity for anaerobic degradation of sulfated polysaccharides, as evidenced by 202 carbohydrate-active enzymes (CAZymes) and 165 sulfatases. Additionally, its ability of nitrogen fixation was confirmed by nitrogenase activity detected during growth on nitrogen-free medium, and the presence of nitrogenases (nifDKH) encoded in the genome. Based on the physiological and genomic analyses, this strain represents a new species of bacteria that may play an important role in the degradation of macroalgal polysaccharides and with relevance to the biogeochemical cycling of carbon, sulfur, and nitrogen in marine environments. Strain NLcol2T (= DSM 113125T = MCCC 1K08672T) is proposed to be the type strain of a novel species in the Pontiella genus, and the name Pontiella agarivorans sp. nov. is proposed.IMPORTANCEGrowth and intentional burial of marine macroalgae is being considered as a carbon dioxide reduction strategy but elicits concerns as to the fate and impacts of this macroalgal carbon in the ocean. Diverse heterotrophic microbial communities in the ocean specialize in these complex polymers such as carrageenan and fucoidan, for example, members of the Kiritimatiellota phylum. However, only four type strains within the phylum have been cultivated and characterized to date, and there is limited knowledge about the metabolic capabilities and functional roles of related organisms in the environment. The new isolate strain NLcol2T expands the known substrate range of this phylum and further reveals the ability to fix nitrogen during anaerobic growth on macroalgal polysaccharides, thereby informing the issue of macroalgal carbon disposal.


Assuntos
Alteromonadaceae , Bactérias Anaeróbias , Anaerobiose , Composição de Bases , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Filogenia , Análise de Sequência de DNA , Bactérias Anaeróbias/metabolismo , Polissacarídeos/metabolismo , Alteromonadaceae/genética , Carragenina , DNA Bacteriano/análise , Ácidos Graxos , Técnicas de Tipagem Bacteriana
7.
BMC Genomics ; 24(1): 695, 2023 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-37986036

RESUMO

BACKGROUND: Despite a rising interest in the diversity and ecology of fungi in marine environments, there are few published genomes of fungi isolated from the ocean. The basidiomycetous yeast (unicellular fungus) genus Rhodotorula are prevalent and abundant in the open ocean, and they have been isolated from a wide range of other environments. Many of these environments are nutrient poor, such as the Antarctica and the Atacama deserts, raising the question as to how Rhodotorula yeasts may have adapted their metabolic strategies to optimize survival under low nutrient conditions. In order to understand their adaptive strategies in the ocean, the genome of R. sphaerocarpa ETNP2018 was compared to that of fourteen representative Rhodotorula yeasts, isolated from a variety of environments. RESULTS: Rhodotorula sphaerocarpa ETNP2018, a strain isolated from the oligotrophic part of the eastern tropical North Pacific (ETNP) oxygen minimum zone (OMZ), hosts the smallest of the fifteen genomes and yet the number of protein-coding genes it possesses is on par with the other strains. Its genome exhibits a distinct reduction in genes dedicated to Major Facilitator Superfamily transporters as well as biosynthetic enzymes. However, its core metabolic pathways are fully conserved. Our research indicates that the selective pressures of the ETNP OMZ favor a streamlined genome with reduced overall biosynthetic potential balanced by a stable set of core metabolisms and an expansion of mechanisms for nutrient acquisition. CONCLUSIONS: In summary, this study offers insights into the adaptation of fungi to the oligotrophic ocean and provides valuable information for understanding the ecological roles of fungi in the ocean.


Assuntos
Rhodotorula , Rhodotorula/genética , Leveduras , Genômica , Oceanos e Mares , Filogenia
8.
Entropy (Basel) ; 25(10)2023 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-37895505

RESUMO

The assessment of seismic risk and the prevention of earthquake occurrences during reservoir operation present significant challenges in terms of accurate determination. This study aims to address this issue by developing a numerical model. The primary objective is to estimate the vulnerability of different fault types to reservoir impoundment. This model integrates essential parameters such as fault dip and the relative orientation between the reservoir and potential earthquakes, and it is structured within a risk framework using polar coordinates. Through comprehensive computations, we evaluate the alterations in elastic stress and fluid pore pressure resulting from water impoundment. This is achieved by employing a fully coupled two-dimensional poroelastic approach. Furthermore, our model incorporates relevant seismic data to enhance its accuracy. The findings of our study underscore that the critical factor lies in the fault's precise positioning with respect to the reservoir. The risk associated with a fault is contingent upon both its location and its orientation, emphasizing the importance of these factors in determining hazardous zones.

9.
Opt Express ; 31(18): 29440-29451, 2023 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-37710744

RESUMO

Supercontinuum sources with high compactness are essential for applications such as optical sensing, airborne detection and communication systems. In the past decades, the adoption of bulky optical parametric amplifier to pump various chalcogenide glass waveguides are widely reported for on-chip mid-infrared supercontinuum generation, but this usually leads to a large volume of the whole system, and is not practical. Therefore, integrating advanced femtosecond fiber lasers with optical waveguides using nano-fabrication technology are highly desired. However, the scarcity of compact pump sources and the dispersion-matched high-nonlinearity waveguide in short wavelength regions have hindered the advancement of integrated supercontinuum source performances in the near and mid-infrared region. In this study, we demonstrate a broadband supercontinuum source from As2S3 waveguide pumped by a compact dual-femtosecond solitons pulse source. The laser is completely fiber structured, and its wavelength can be readily tuned from 2 to 2.3 µm using Raman soliton self-frequency shift technology in a Tm3+-doped fiber amplifier. Furthermore, the As2S3 waveguide is designed with controllable dispersion and high nonlinearity for a broadband supercontinuum generation. These results will advance the development of on-chip supercontinuum sources based on chalcogenide waveguides.

10.
Nanotechnology ; 34(44)2023 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-37527642

RESUMO

Recently, narrow bandgap tin-lead mixed perovskite solar cells (PSCs) have become a research hotspot because they can be applied in tandem cells to break the Shockley-Queisser radiative limit of the single junction PSCs. However, the introduction of tin, on the one hand, makes the crystal quality of perovskite thin film worse, leading to the increase of film defects; on the other hand, the easy oxidation of divalent tin also leads to the increase of defect states, which seriously affects the photoelectric conversion efficiency of tin-lead cell devices. Good crystallization and low defect density of perovskite layer are very important to ensure good light absorption and photogenerated carrier generation and transport. Here, we adjust the crystallization of tin-lead perovskite films by a Lewis base-urea (CO(NH2)2), which significantly increases the grain size and improves the film morphology. At the same time, because of the Lewis base property of urea, the uncoordinated Pb2+and Sn2+defects of Lewis acids in the tin-lead films are effectively passivated, and the occurrence of non-radiative recombination in the films is reduced. Under the dual effects of improving crystallization and passivating defects, the photoelectric performance of tin-lead perovskite solar cell devices is significantly improved to 18.1% compared with the original device of 15.4%.

11.
Front Bioeng Biotechnol ; 11: 1223831, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37520296

RESUMO

Introduction: The lower limb exoskeleton rehabilitation robot should perform gait planning based on the patient's motor intention and training status and provide multimodal and robust control schemes in the control strategy to enhance patient participation. Methods: This paper proposes an adaptive particle swarm optimization admittance control algorithm (APSOAC), which adaptively optimizes the weights and learning factors of the PSO algorithm to avoid the problem of particle swarm falling into local optimal points. The proposed improved adaptive particle swarm algorithm adjusts the stiffness and damping parameters of the admittance control online to reduce the interaction force between the patient and the robot and adaptively plans the patient's desired gait profile. In addition, this study proposes a dual RBF neural network adaptive sliding mode controller (DRNNASMC) to track the gait profile, compensate for frictional forces and external perturbations generated in the human-robot interaction using the RBF network, calculate the required moments for each joint motor based on the lower limb exoskeleton dynamics model, and perform stability analysis based on the Lyapunov theory. Results and discussion: Finally, the efficiency of the APSOAC and DRNNASMC algorithms is demonstrated by active and passive walking experiments with three healthy subjects, respectively.

13.
PeerJ ; 11: e14557, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36778148

RESUMO

Forest fires are one of the significant disturbances in forest ecosystems. It is essential to extract burned areas rapidly and accurately to formulate forest restoration strategies and plan restoration plans. In this work, we constructed decision trees and used a combination of differential normalized burn ratio (dNBR) index and OTSU threshold method to extract the heavily and mildly burned areas. The applicability of this method was evaluated with three fires in Muli County, Sichuan, China, and we concluded that the extraction accuracy of this method could reach 97.69% and 96.37% for small area forest fires, while the extraction accuracy was lower for large area fires, only 89.32%. In addition, the remote sensing environment index (RSEI) was used to evaluate the ecological environment changes. It analyzed the change of the RSEI level through the transition matrix, and all three fires showed that the changes in RSEI were stronger for heavily burned areas than for mildly burned areas, after the forest fire the ecological environment (RSEI) was reduced from good to moderate. These results realized the quantitative evaluation and dynamic evaluation of the ecological environment condition, providing an essential basis for the restoration, decision making and management of the affected forests.


Assuntos
Queimaduras , Ecossistema , Humanos , Tecnologia de Sensoriamento Remoto , Monitoramento Ambiental , Florestas
14.
Comput Intell Neurosci ; 2022: 4278849, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36052037

RESUMO

In this study, we focus on the relevance of remaining life prediction of randomly degraded equipment in the context of big data monitoring and the core issue of quantifying uncertainty in remaining life prediction. We analyze the limitations and common problems of current research. To address the limitations and common problems, a solution for predicting the remaining life of randomly degraded devices with multisource sensing monitoring in the context of big data is proposed, and the feasibility and effectiveness of the idea are verified using battery data. Finally, multiple machine learning methods, such as support vector machines, random forests, recurrent neural networks, and convolutional neural networks, are combined to predict the remaining life of batteries, and these four machine learning methods perform well in the work of battery remaining life prediction and solve the key scientific problems.


Assuntos
Big Data , Aprendizado de Máquina , Armazenamento e Recuperação da Informação , Tecnologia
15.
J Mol Endocrinol ; 69(2): 315-327, 2022 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-35604113

RESUMO

We tried to unveil the clinical significance of miR-146a as a biomarker in M2 macrophage polarization in diabetic wound healing. Initially, we found reduced miR-146a in macrophages of diabetic patients. Next, dual-luciferase assay verified that toll-like receptor 4 (TLR4) was a target gene of miR-146 and was negatively regulated by miR-146. Moreover, after ectopic expression and depletion experiments of miR-146 and/or TLR4, lipopolysaccharide-induced inflammatory response of macrophages was detected. The results revealed that overexpression of miR-146a promoted the M2 macrophage polarization by suppressing the TLR4/nuclear factor-kappaB (NF-κB) axis, so as to enhance wound healing in diabetic ulcers. Further, mouse models with diabetic ulcers were established to investigate the effects of miR-146a on diabetic wound healing in vivo, which revealed that miR-146a promoted wound healing in diabetic ulcers by inhibiting the TLR4/NF-κB axis. In conclusion, we demonstrate that miR-146a can induce M2 macrophage polarization to enhance wound healing in diabetic ulcers by inhibiting the TLR4/NF-κB axis.


Assuntos
Complicações do Diabetes , Ativação de Macrófagos , MicroRNAs , Cicatrização , Animais , Complicações do Diabetes/metabolismo , Diabetes Mellitus/metabolismo , Humanos , Macrófagos/metabolismo , Camundongos , MicroRNAs/genética , MicroRNAs/metabolismo , NF-kappa B/metabolismo , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/metabolismo , Úlcera/metabolismo , Cicatrização/genética
16.
Nanoscale ; 14(4): 1219-1225, 2022 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-34989751

RESUMO

Tin (Sn)-based perovskite solar cells (PSCs) have attracted much attention because they are more environmentally friendly than lead-based PSCs. However, the fast crystallization of Sn-based perovskite films and the easy oxidation of Sn2+ to Sn4+ hinder the improvement of their efficiency and stability. In this work, ethylammonium bromide (EABr) was added to methylammonium tin iodide (MASnI3) perovskite precursor solution to regulate the crystallization dynamics and improve the film morphology. The results show that the large EA+ ions slow down the crystallization process of Sn-based perovskites and form a smooth perovskite film with high crystallinity, while the added Br- anions further improved the crystallinity and orientation of the perovskite film. Under the combined action of EA+ and Br- ions, the as-produced PSCs achieved a champion power conversion efficiency (PCE) of 9.59%. The EABr additive also retarded the oxidation of Sn2+, and the solar cell device maintained 93% of its initial efficiency after 30 days in a nitrogen-filled glove box without being encapsulated. This work provides a new strategy for the realization of high-efficiency Sn-based PSCs.

17.
Phys Med Biol ; 66(23)2021 11 29.
Artigo em Inglês | MEDLINE | ID: mdl-34727529

RESUMO

The automatic detection of liver tumors by computed tomography is challenging, owing to their wide variations in size and location, as well as to their irregular shapes. Existing detection methods largely rely on two-stage detectors and use CT images marked with bounding boxes for training and detection. In this study, we propose a single-stage detector method designed to accurately detect multiple tumors simultaneously, and provide results demonstrating its increased speed and efficiency compared to prior methods. The proposed model divides CT images into multiple channels to obtain continuity information and implements a bounding box attention mechanism to overcome the limitation of inaccurate prediction of tumor center points and decrease redundant bounding boxes. The model integrates information from various channels using an effective Squeeze-and-Excitation attention module. The proposed model obtained a mean average precision result of 0.476 on the Decathlon dataset, which was superior to that of the prior methods examined for comparison. This research is expected to enable physicians to diagnose tumors very efficiently; particularly, the prediction of tumor center points is expected to enable physicians to rapidly verify their diagnostic judgments. The proposed method is considered suitable for future adoption in clinical practice in hospitals and resource-poor areas because its superior performance does not increase computational cost; hence, the equipment required is relatively inexpensive.


Assuntos
Neoplasias Hepáticas , Abdome , Humanos , Neoplasias Hepáticas/diagnóstico por imagem , Compostos Radiofarmacêuticos , Tomografia Computadorizada por Raios X
18.
J Fungi (Basel) ; 7(10)2021 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-34682226

RESUMO

Airborne microbial communities directly impact the health of humans, animals, plants, and receiving ecosystems. While airborne bacterial and fungal communities have been studied by both cultivation-based methods and metabarcoding surveys targeting specific molecular markers, fewer studies have used shotgun metagenomics to study the airborne mycobiome. We analyzed the diversity and relative abundance of fungi in nine airborne metagenomes collected on clear days ("background") and during dust storms in the Eastern Mediterranean. The negative correlation between the relative abundance of fungal reads and the concentrations of atmospheric particulate matter having an aerodynamic diameter smaller than 10 µm (PM10) indicate that dust storms lower the proportion of fungi in the airborne microbiome, possibly due to the lower relative abundance of fungi in the dust storm source regions and/or more effective transport of bacteria by the dust. Airborne fungal community composition was altered by the dust storms, particularly those originated from Syria, which was enriched with xerophilic fungi. We reconstructed a high-quality fungal metagenome-assembled genome (MAG) from the order Cladosporiales, which include fungi known to adapt to environmental extremes commonly faced by airborne microbes. The negative correlation between the relative abundance of Cladosporiales MAG and PM10 concentrations indicate that its origin is dominated by local sources and likely includes the indoor environments found in the city.

19.
Environ Sci Technol ; 55(15): 10832-10842, 2021 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-34291904

RESUMO

Salt marsh sediments are known hotspots for nitrogen cycling, including the production and consumption of nitrous oxide (N2O), a potent greenhouse gas and ozone-depleting agent. Coastal eutrophication, particularly elevated nitrogen loading from the application of fertilizers, is accelerating nitrogen cycling processes in salt marsh sediments. Here, we examine the impact of long-term fertilization on nitrogen cycling processes with a focus on N2O dynamics in a New England salt marsh. By combining 15N-tracer experiments with numerical modeling, we found that both nitrification and denitrification contribute to net N2O production in fertilized sediments. Long-term fertilization increased the relative importance of nitrification to N2O production, likely a result of increased oxygen penetration from nutrient-induced increases in marsh elevation. Substrate utilization rates of key nitrogen cycling processes revealed links between functions and the corresponding microbial communities. Higher specific substrate utilization rates leading to N2O production from nitrification in fertilized sediments indicate a shift in the community composition of ammonia oxidizers, whereas the lack of change in specific substrate utilization of N2O production from denitrification under long-term fertilization suggests resilience of the denitrifying communities. Both are consistent with previous studies on the functional gene community composition in these experimental plots.


Assuntos
Óxido Nitroso , Áreas Alagadas , Desnitrificação , Fertilização , Nitrificação , Nitrogênio
20.
Nat Commun ; 12(1): 3076, 2021 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-34031405

RESUMO

Changes in the sequence of an organism's genome, i.e., mutations, are the raw material of evolution. The frequency and location of mutations can be constrained by specific molecular mechanisms, such as diversity-generating retroelements (DGRs). DGRs have been characterized from cultivated bacteria and bacteriophages, and perform error-prone reverse transcription leading to mutations being introduced in specific target genes. DGR loci were also identified in several metagenomes, but the ecological roles and evolutionary drivers of these DGRs remain poorly understood. Here, we analyze a dataset of >30,000 DGRs from public metagenomes, establish six major lineages of DGRs including three primarily encoded by phages and seemingly used to diversify host attachment proteins, and demonstrate that DGRs are broadly active and responsible for >10% of all amino acid changes in some organisms. Overall, these results highlight the constraints under which DGRs evolve, and elucidate several distinct roles these elements play in natural communities.


Assuntos
Ecologia , Evolução Molecular , Microbiota/genética , Microbiota/fisiologia , Mutação , Bactérias/genética , Bacteriófagos/fisiologia , Biodiversidade , Ecossistema , Microbiologia Ambiental , Variação Genética , Metagenoma , Filogenia , Retroelementos
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