Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 222
Filter
1.
Cancer Immunol Immunother ; 73(12): 242, 2024 Oct 03.
Article in English | MEDLINE | ID: mdl-39358613

ABSTRACT

The biotechnological development of monoclonal antibodies and their immunotherapeutic use in oncology have grown exponentially in the last decade, becoming the first-line therapy for some types of cancer. Their mechanism of action is based on the ability to regulate the immune system or by interacting with targets that are either overexpressed in tumor cells, released into the extracellular milieu or involved in processes that favor tumor growth. In addition, the intrinsic characteristics of each subclass of antibodies provide specific effector functions against the tumor by activating antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, and antibody-dependent cellular phagocytosis, among other mechanisms. The rational design and engineering of monoclonal antibodies have improved their pharmacokinetic and pharmacodynamic features, thus optimizing the therapeutic regimens administered to cancer patients and improving their clinical outcomes. The selection of the immunoglobulin G subclass, modifications to its crystallizable region (Fc), and conjugation of radioactive substances or antineoplastic drugs may all improve the antitumor effects of therapeutic antibodies. This review aims to provide insights into the immunological and pharmacological aspects of therapeutic antibodies used in oncology, with a rational approach at molecular modifications that can be introduced into these biological tools, improving their efficacy in the treatment of cancer.


Subject(s)
Neoplasms , Humans , Neoplasms/immunology , Neoplasms/drug therapy , Neoplasms/therapy , Animals , Immunotherapy/methods , Antibodies, Monoclonal/therapeutic use , Antibodies, Monoclonal/immunology , Antineoplastic Agents, Immunological/therapeutic use , Antineoplastic Agents, Immunological/pharmacology , Antibody-Dependent Cell Cytotoxicity/immunology
2.
mSphere ; : e0019224, 2024 Sep 17.
Article in English | MEDLINE | ID: mdl-39287428

ABSTRACT

Soil microorganisms mediate several biological processes through the secretion of natural products synthesized in specialized metabolic pathways, yet functional characterization in ecological contexts remains challenging. Using culture-independent metagenomic analyses of microbial DNA derived directly from soil samples, we examined the potential of biosynthetic gene clusters (BGCs) from six bacterial communities distributed along an altitudinal gradient of the Andes Mountains in the Atacama Desert. We mined 38 metagenome-assembled genomes (MAGs) and identified 168 BGCs. Results indicated that most predicted BGCs were classified as non-ribosomal-peptides (NRP), post-translational modified peptides (RiPP), and terpenes, which were mainly identified in genomes of species from Acidobacteriota and Proteobacteria phyla. Based on BGC composition according to types of core biosynthetic genes, six clusters of MAGs were observed, three of them with predominance for a single phylum, of which two also showed specificity to a single sampling site. Comparative analyses of accessory genes in BGCs showed associations between membrane transporters and other protein domains involved in specialized metabolism with classes of biosynthetic cores, such as resistance-nodulation-cell division (RND) multidrug efflux pumps with RiPPs and the iron-dependent transporter TonB with terpenes. Our findings increase knowledge regarding the biosynthetic potential of uncultured bacteria inhabiting pristine locations from one of the oldest and driest nonpolar deserts on Earth.IMPORTANCEMuch of what we know about specialized metabolites in the Atacama Desert, including Andean ecosystems, comes from isolated microorganisms intended for drug development and natural product discovery. To complement research on the metabolic potential of microbes in extreme environments, comparative analyses on functional annotations of biosynthetic gene clusters (BGCs) from uncultivated bacterial genomes were carried out. Results indicated that in general, BGCs encode for structurally unique metabolites and that metagenome-assembled genomes did not show an obvious relationship between the composition of their core biosynthetic potential and taxonomy or geographic distribution. Nevertheless, some members of Acidobacteriota showed a phylogenetic relationship with specific metabolic traits and a few members of Proteobacteria and Desulfobacterota exhibited niche adaptations. Our results emphasize that studying specialized metabolism in environmental samples may significantly contribute to the elucidation of structures, activities, and ecological roles of microbial molecules.

3.
Appl Phys Rev ; 11(3): 031314, 2024 Sep.
Article in English | MEDLINE | ID: mdl-39221036

ABSTRACT

With the rapid development and popularization of additive manufacturing, different technologies, including, but not limited to, extrusion-, droplet-, and vat-photopolymerization-based fabrication techniques, have emerged that have allowed tremendous progress in three-dimensional (3D) printing in the past decades. Bioprinting, typically using living cells and/or biomaterials conformed by different printing modalities, has produced functional tissues. As a subclass of vat-photopolymerization bioprinting, digital light processing (DLP) uses digitally controlled photomasks to selectively solidify liquid photocurable bioinks to construct complex physical objects in a layer-by-layer manner. DLP bioprinting presents unique advantages, including short printing times, relatively low manufacturing costs, and decently high resolutions, allowing users to achieve significant progress in the bioprinting of tissue-like complex structures. Nevertheless, the need to accommodate different materials while bioprinting and improve the printing performance has driven the rapid progress in DLP bioprinters, which requires multiple pieces of knowledge ranging from optics, electronics, software, and materials beyond the biological aspects. This raises the need for a comprehensive review to recapitulate the most important considerations in the design and assembly of DLP bioprinters. This review begins with analyzing unique considerations and specific examples in the hardware, including the resin vat, optical system, and electronics. In the software, the workflow is analyzed, including the parameters to be considered for the control of the bioprinter and the voxelizing/slicing algorithm. In addition, we briefly discuss the material requirements for DLP bioprinting. Then, we provide a section with best practices and maintenance of a do-it-yourself DLP bioprinter. Finally, we highlight the future outlooks of the DLP technology and their critical role in directing the future of bioprinting. The state-of-the-art progress in DLP bioprinter in this review will provide a set of knowledge for innovative DLP bioprinter designs.

4.
J Clin Med ; 13(16)2024 Aug 10.
Article in English | MEDLINE | ID: mdl-39200846

ABSTRACT

Background/Objectives: Elevated glycemic variability (GV) has been associated with postoperative morbidity. Traditional preoperative fasting guidelines may contribute to high GV by driving the body into catabolism. Enhanced recovery after surgery (ERAS) protocols that include a preoperative carbohydrate load (PCL) reduce hospital length of stay and healthcare costs; however, it remains unclear whether PCL improves GV in surgical patients. The aim of this retrospective study was to determine the effect of a PCL on postoperative GV in diabetic and non-diabetic patients having gynecological surgery. Methods: Retrospective data were collected on patients who had gynecological surgery before and after the rollout of an institutional ERAS protocol that included PCL ingestion. The intervention group included patients who underwent surgery in 2019 and were enrolled in the ERAS protocol and, therefore, received a PCL. The control group included patients who underwent surgery in 2016 and, thus, were not enrolled in the protocol. The primary endpoint was GV, calculated by the coefficient of variance (CV) and glycemic lability index (GLI). Results: A total of 63 patients in the intervention group and 45 in the control were analyzed. GV was not statistically significant between the groups for CV (19.3% vs. 18.6%, p = 0.65) or GLI (0.58 vs. 0.54, p = 0.86). Postoperative pain scores (4.5 vs. 5.2 p = 0.23) and incentive spirometry measurements (1262 vs. 1245 p = 0.87) were not significantly different. A subgroup analysis of patients with and without type 2 diabetes mellitus revealed no significant differences in GV for any of the subgroups. Conclusions: This retrospective review highlights the need for additional GV research, including consensus agreement on a gold standard GV measurement. Large-scale prospective studies are needed to test the effectiveness of the PCL in reducing GV.

5.
Cureus ; 16(6): e61624, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38966450

ABSTRACT

The article describes a successful clinical outcome in the case of a 24-year-old male with a diagnosis of an ostium secundum atrial defect secondary to a perforated aneurysm associated with vena cava agenesis. During hospitalization, an echocardiogram revealed the presence of ostium secundum inter-atrial communication with a left to right shunt, a left ventricular ejection fraction (LVEF) of 60%, and mild pulmonary hypertension, measured at 40 mmHg. CT imaging showed anomalous dilation of the azygos vein (16.8 mm), associated with interruption of the vena cava in the intrahepatic and adrenal portion, continuing through the azygos system and draining into the superior vena cava. Open-heart surgery was performed with pericardium patch placement on the defect. Postoperative transthoracic echocardiography revealed a tracking of the interatrial septum, with adequate placement of the surgical patch and no evidence of residual short circuits. The postoperative recovery was favorable, and the patient was discharged five days after surgery. Outpatient monitoring at the first and third months showed no complications during physical examination and echocardiogram imaging.

6.
Medicina (B.Aires) ; Medicina (B.Aires);84(2): 333-336, jun. 2024. graf
Article in Spanish | LILACS-Express | LILACS | ID: biblio-1564788

ABSTRACT

Resumen La nutrición enteral por yeyunostomía es una prác tica frecuente en cualquier servicio de cirugía general, esta conlleva bajo riesgo de complicaciones y morbi mortalidad. Presentamos el caso de una paciente con antecedente inmediato de gastrectomía subtotal que inició nutrición por yeyunostomía y complicó con ne crosis intestinal por isquemia no oclusiva en el corto lapso. La finalidad de este trabajo es informar sobre esta complicación, su fisiopatología y factores de riesgo para tenerla en cuenta y poder tomar precozmente una conducta terapéutica adecuada.


Abstract Enteral nutrition through jejunostomy is a common practice in any general surgery service; it carries a low risk of complications and morbidity and mortality. We present the case of a patient with an immediate history of subtotal gastrectomy that began nutrition through jejunostomy and complicated with intestinal necrosis due to non-occlusive ischemia in the short period. The purpose of this work is to report on this complication, its pathophysiology and risk factors to take it into account and be able to take appropriate therapeutic action early.

7.
BMC Genomics ; 25(1): 614, 2024 Jun 18.
Article in English | MEDLINE | ID: mdl-38890559

ABSTRACT

BACKGROUND: To unravel the evolutionary history of a complex group, a comprehensive reconstruction of its phylogenetic relationships is crucial. This requires meticulous taxon sampling and careful consideration of multiple characters to ensure a complete and accurate reconstruction. The phylogenetic position of the Orestias genus has been estimated partly on unavailable or incomplete information. As a consequence, it was assigned to the family Cyprindontidae, relating this Andean fish to other geographically distant genera distributed in the Mediterranean, Middle East and North and Central America. In this study, using complete genome sequencing, we aim to clarify the phylogenetic position of Orestias within the Cyprinodontiformes order. RESULTS: We sequenced the genome of three Orestias species from the Andean Altiplano. Our analysis revealed that the small genome size in this genus (~ 0.7 Gb) was caused by a contraction in transposable element (TE) content, particularly in DNA elements and short interspersed nuclear elements (SINEs). Using predicted gene sequences, we generated a phylogenetic tree of Cyprinodontiformes using 902 orthologs extracted from all 32 available genomes as well as three outgroup species. We complemented this analysis with a phylogenetic reconstruction and time calibration considering 12 molecular markers (eight nuclear and four mitochondrial genes) and a stratified taxon sampling to consider 198 species of nearly all families and genera of this order. Overall, our results show that phylogenetic closeness is directly related to geographical distance. Importantly, we found that Orestias is not part of the Cyprinodontidae family, and that it is more closely related to the South American fish fauna, being the Fluviphylacidae the closest sister group. CONCLUSIONS: The evolutionary history of the Orestias genus is linked to the South American ichthyofauna and it should no longer be considered a member of the Cyprinodontidae family. Instead, we submit that Orestias belongs to the Orestiidae family, as suggested by Freyhof et al. (2017), and that it is the sister group of the Fluviphylacidae family, distributed in the Amazonian and Orinoco basins. These two groups likely diverged during the Late Eocene concomitant with hydrogeological changes in the South American landscape.


Subject(s)
Cyprinodontiformes , Evolution, Molecular , Genome , Phylogeny , Animals , Cyprinodontiformes/genetics , Cyprinodontiformes/classification , DNA Transposable Elements/genetics , Genome Size
8.
Anesth Analg ; 139(1): e4-e5, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-38885402
9.
Int J Cardiovasc Imaging ; 40(6): 1319-1328, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38634941

ABSTRACT

Scimitar Syndrome is part of a complex spectrum of congenital cardiovascular anomalies related to anomalous pulmonary venous return. Depending on the extent of involvement, treatment can be either expectant or surgical. Prognosis and survival have been controversial, with some results supporting early surgical management. This research aims to disclose the outcomes and describe the management, clinical and imaging characteristics of patients diagnosed with Scimitar Syndrome treated in a tertiary referral healthcare center. Longitudinal descriptive observational study. The study included all patients diagnosed with scimitar syndrome in our institution between January/2011 and December/2022. A description of the sociodemographic and clinical characteristics, diagnostic tools used, treatment features, and patient outcomes is provided. Eleven patients were included, with a mean age at diagnosis of five years (CI 0-17), six of which were female (54.55%). Nine (81.82%) patients had evidence of a scimitar vein on the chest radiograph, six (54.55%) cardiac dextroposition, six (54.55%) pulmonary hypoplasia, five (45.45%) right pulmonary artery hypoplasia, and three (27.27%) had aortopulmonary collaterals. Four (36.36%) patients had horseshoe lungs, and four (36.36%) had bronchopulmonary sequestration. In the associations, two (18.18%) patients were found to have an atrial septal defect, three (27.27%) ventricular septal defect, and one (9%) had Tetralogy of Fallot. Pulmonary hypertension was demonstrated in two (18.18%) patients. Seven (63.64%) required surgical management to correct the scimitar vein, and two patients died due to unrelated complications. Scimitar syndrome presents diagnostic and treatment challenges, necessitating a multidisciplinary approach for timely care. Chest radiography and CT scans are primary diagnostic tools, with surgical intervention often warranted alongside other heart defects or significant hemodynamic repercussions. Medical management is effective for mild to moderate cases. Long-term patient outcomes remain uncertain due to study limitations, but improved life expectancy is anticipated with ongoing care.


Subject(s)
Predictive Value of Tests , Scimitar Syndrome , Tertiary Care Centers , Humans , Scimitar Syndrome/diagnostic imaging , Scimitar Syndrome/surgery , Scimitar Syndrome/physiopathology , Scimitar Syndrome/mortality , Scimitar Syndrome/therapy , Female , Male , Colombia , Child, Preschool , Child , Infant , Adolescent , Treatment Outcome , Infant, Newborn , Longitudinal Studies , Time Factors , Retrospective Studies , Pulmonary Circulation , Cardiac Surgical Procedures
10.
Rev Alerg Mex ; 71(1): 72, 2024 Feb 01.
Article in Spanish | MEDLINE | ID: mdl-38683089

ABSTRACT

METHODS: We took Peripheral blood samples from adult patients over 60 years of age with a confirmed diagnosis of IPF through biopsy or clinical criteria. Plasma separation was performed, and proinflammatory cytokines were measured using CBA. This study received approval from the ethics and research committee of the Colombian Pulmonological Foundation. RESULTS: Patients with IPF exhibited an increase in cytokines such as IL-4, INFy, and IL-6 compared to healthy older adults. CONCLUSION: Inflammatory disease has been associated with the development and coexistence of multiple chronic non-communicable diseases that have a higher incidence after 65 years of age. The involvement of adaptive immunity in the pathogenesis of IPF has been described as an imbalance in the Th1/Th2 lymphocyte response. Further studies are required to identify additional markers of immunosenescence that correlate with IPF.


OBJETIVO: Identificar citoquinas proinflamatorias en el plasma de pacientes con FPI residentes en la altura de Bogotá. MÉTODOS: Se tomaron muestras de sangre periférica de pacientes adultos mayores de 60 años, con diagnóstico de FPI confirmado por biopsia o por criterios clínicos. Se realizó la separación de plasma y se midieron citoquinas proinflamatorias por CBA. Este trabajo fue aprobado por el Comité de Ética e Investigaciones de la Fundación Neumológica Colombiana. RESULTADOS: Los pacientes con FPI mostraron un aumento de citocinas como la IL-4, INFy e IL-6, en comparación con adultos mayores sanos. CONCLUSIÓN: El inflammaging ha sido asociado con el desarrollo y coexistencia de múltiples enfermedades crónicas no transmisibles que tienen mayor incidencia después de los 65 años. Se ha descrito la participación de la inmunidad adaptativa con la patogénesis de la FPI, como un desbalance en la respuesta de linfocitos Th1/Th2. Es necesario realizar más estudios que permitan identificar otros marcadores de inmunosenescencia que se correlacionen con la FPI.


Subject(s)
Idiopathic Pulmonary Fibrosis , Humans , Idiopathic Pulmonary Fibrosis/etiology , Aged , Male , Female , Middle Aged , Inflammation , Cytokines/blood
11.
Medicina (B Aires) ; 84(2): 333-336, 2024.
Article in Spanish | MEDLINE | ID: mdl-38683519

ABSTRACT

Enteral nutrition through jejunostomy is a common practice in any general surgery service; it carries a low risk of complications and morbidity and mortality. We present the case of a patient with an immediate history of subtotal gastrectomy that began nutrition through jejunostomy and complicated with intestinal necrosis due to non-occlusive ischemia in the short period. The purpose of this work is to report on this complication, its pathophysiology and risk factors to take it into account and be able to take appropriate therapeutic action early.


La nutrición enteral por yeyunostomía es una práctica frecuente en cualquier servicio de cirugía general, esta conlleva bajo riesgo de complicaciones y morbimortalidad. Presentamos el caso de una paciente con antecedente inmediato de gastrectomía subtotal que inició nutrición por yeyunostomía y complicó con necrosis intestinal por isquemia no oclusiva en el corto lapso. La finalidad de este trabajo es informar sobre esta complicación, su fisiopatología y factores de riesgo para tenerla en cuenta y poder tomar precozmente una conducta terapéutica adecuada.


Subject(s)
Enteral Nutrition , Intestinal Perforation , Jejunostomy , Necrosis , Female , Humans , Middle Aged , Enteral Nutrition/adverse effects , Gastrectomy/adverse effects , Intestinal Perforation/etiology , Intestinal Perforation/surgery , Jejunostomy/adverse effects , Necrosis/etiology
12.
Cureus ; 16(1): e53294, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38435917

ABSTRACT

We present a 47-year-old male without a relevant history or past respiratory diseases. He debuted with an acute, non-complicated COVID-19 infection, and later he started with mMRC-2 dyspnea, accompanied by a non-expectorant cough of four months evolution. A CT thoracic scan showed a dilatation of the aerial homogenous space and a well-defined anterior left pericardiac level, and a pericardial left bulla was diagnosed. The patient was treated with surgical intervention by video-assisted thoracoscopic surgery and had an adequate post-surgical evolution. The PPT must be managed by a multidisciplinary team with the definitive treatment of surgical resection.

13.
Rev Esp Anestesiol Reanim (Engl Ed) ; 71(1): 8-16, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37683971

ABSTRACT

OBJECTIVE: To analyse the impact of 10 years of blended echocardiography teaching. METHODS AND RESULTS: A questionnaire was emailed to all medical doctors who graduated from the blended learning diploma in echocardiography developed by the University of Chile and taught by a team from Chile and Spain. One hundred and forty of the 210 students who graduated from the program between 2011 and 2020 completed the questionnaire: 53.57% were anaesthesiologists, and 26.42% were intensivists. More than 85% of respondents indicated that the online teaching met their expectations, and 70.2% indicated that the hands-on practice fulfilled the stated objectives. In a retrospective analysis using self-reported data, graduates reported that their use of transthoracic and transoesophageal echocardiography has increased from 24.29% to 40.71% and from 13.57% to 27.86%, repectively, after the programme compared to before the programme. They used echocardiography mainly in the perioperative period (56.7%) and during intensive care (32.3%), while only 11% of respondents used it in emergency care units. Nearly all (92.4%) respondents reported that the skills learned was very useful in their professional practice. CONCLUSIONS: Ten years after its launch, the blended learning diploma in echocardiography was well rated by graduate specialists, and is associated with a significant increase in the use of echocardiography in the perioperative period and during intensive care. The main challenges are to establish a longer period of practice and achieve greater implantation in emergency medicine.


Subject(s)
Echocardiography , Students , Humans , Retrospective Studies , Surveys and Questionnaires , Echocardiography, Transesophageal
16.
Int J Mol Sci ; 24(19)2023 Oct 03.
Article in English | MEDLINE | ID: mdl-37834314

ABSTRACT

Lactose intolerance (LI) and vitamin D deficiency (VDD) have been linked to inflammatory bowel disease (IBD). We conducted an observational study in 192 Chilean IBD patients to investigate the prevalence of a specific gene variant (LCT-13910 CC genotype) associated with LI and the prevalence of VDD/Vitamin D Receptor (VDR) gene variants. Blood samples were analyzed using Illumina's Infinium Global Screening Array. The LCT-13910 CC genotype was found in 61% of IBD patients, similar to Chilean Hispanic controls and lower than Chilean Amerindian controls. The frequency of the LCT-13910-C allele in Chilean IBD patients (0.79) was comparable to the general population and higher than Europeans (0.49). Regarding VDR and VDD variants, in our study, the rs12785878-GG variant was associated with an increased risk of IBD (OR = 2.64, CI = 1.61-4.32; p-value = 0.001). Sixty-one percent of the Chilean IBD cohort have a genetic predisposition to lactose malabsorption, and a significant proportion exhibit genetic variants associated with VDD/VDR. Screening for LI and VDD is crucial in this Latin American IBD population.


Subject(s)
Inflammatory Bowel Diseases , Lactose , Receptors, Calcitriol , Humans , Chile/epidemiology , Genetic Predisposition to Disease , Genotype , Inflammatory Bowel Diseases/epidemiology , Inflammatory Bowel Diseases/genetics , Inflammatory Bowel Diseases/complications , Lactose/deficiency , Polymorphism, Single Nucleotide , Prevalence , Receptors, Calcitriol/genetics , Vitamin D , Vitamin D Deficiency/complications , Vitamin D Deficiency/epidemiology , Vitamin D Deficiency/genetics
17.
A A Pract ; 17(7): e01705, 2023 Jul 01.
Article in English | MEDLINE | ID: mdl-37463288

ABSTRACT

The delivery of drugs from the manufacturer to the hospital is a complex process. Despite numerous safeguards, lapses may occur, creating the potential for patient harm. Recently, an urban tertiary care medical center received a shipment of isoflurane bottles labeled for veterinary use. This error was not identified until the veterinary isoflurane reached the operating room automated medication dispensing system. No patients received the anesthetic. This report describes how such an error occurred, explains the differences between veterinary and human medications, and emphasizes the importance of vigilance in the drug supply chain to prevent patient harm.


Subject(s)
Isoflurane , Veterinary Drugs , Humans , Medication Errors/prevention & control , Problem-Based Learning , Hospitals
18.
Sensors (Basel) ; 23(12)2023 Jun 08.
Article in English | MEDLINE | ID: mdl-37420605

ABSTRACT

Wearable devices are starting to gain popularity, which means that a large portion of the population is starting to acquire these products. This kind of technology comes with a lot of advantages, as it simplifies different tasks people do daily. However, as they recollect sensitive data, they are starting to be targets for cybercriminals. The number of attacks on wearable devices forces manufacturers to improve the security of these devices to protect them. Many vulnerabilities have appeared in communication protocols, specifically Bluetooth. We focus on understanding the Bluetooth protocol and what countermeasures have been applied during their updated versions to solve the most common security problems. We have performed a passive attack on six different smartwatches to discover their vulnerabilities during the pairing process. Furthermore, we have developed a proposal of requirements needed for maximum security of wearable devices, as well as the minimum requirements needed to have a secure pairing process between two devices via Bluetooth.


Subject(s)
Wearable Electronic Devices , Humans , Computer Security , Communication
19.
Biol Res ; 56(1): 35, 2023 Jun 24.
Article in English | MEDLINE | ID: mdl-37355658

ABSTRACT

BACKGROUND: High mountainous environments are of particular interest as they play an essential role for life and human societies, while being environments which are highly vulnerable to climate change and land use intensification. Despite this, our knowledge of high mountain soils in South America and their microbial community structure is strikingly scarce, which is of more concern considering the large population that depends on the ecosystem services provided by these areas. Conversely, the Central Andes, located in the Mediterranean region of Chile, has long been studied for its singular flora, whose diversity and endemism has been attributed to the particular geological history and pronounced environmental gradients in short distances. Here, we explore soil properties and microbial community structure depending on drainage class in a well-preserved Andean valley on the lower alpine vegetation belt (~2500 m a.s.l.) at 33.5˚S. This presents an opportunity to determine changes in the overall bacterial community structure across different types of soils and their distinct layers in a soil depth profile of a highly heterogeneous environment. METHODS: Five sites closely located (<1.5 km) and distributed in a well preserved Andean valley on the lower alpine vegetation belt (~2500 m a.s.l.) at 33.5˚S were selected based on a pedological approach taking into account soil types, drainage classes and horizons. We analyzed 113 soil samples using high-throughput sequencing of the 16S rRNA gene to describe bacterial abundance, taxonomic composition, and co-occurrence networks. RESULTS: Almost 18,427 Amplicon Sequence Variant (ASVs) affiliated to 55 phyla were detected. The bacterial community structure within the same horizons were very similar validating the pedological sampling approach. Bray-Curtis dissimilarity analysis revealed that the structure of bacterial communities in superficial horizons (topsoil) differed from those found in deep horizons (subsoil) in a site-specific manner. However, an overall closer relationship was observed between topsoil as opposed to between subsoil microbial communities. Alpha diversity of soil bacterial communities was higher in topsoil, which also showed more bacterial members interacting and with higher average connectivity compared to subsoils. Finally, abundances of specific taxa could be considered as biological markers in the transition from topsoil to subsoil horizons, like Fibrobacterota, Proteobacteria, Bacteroidota for shallower soils and Chloroflexi, Latescibacterota and Nitrospirota for deeper soils. CONCLUSIONS: The results indicate the importance of the soil drainage conditions for the bacterial community composition, suggesting that information of both structure and their possible ecological relationships, might be useful in clarifying the location of the edge of the topsoil-subsoil transition in mountainous environments.


Subject(s)
Bacteria , Microbiota , Humans , RNA, Ribosomal, 16S/genetics , Bacteria/genetics , Soil/chemistry , Proteobacteria/genetics , Soil Microbiology
20.
Environ Microbiome ; 18(1): 24, 2023 Mar 28.
Article in English | MEDLINE | ID: mdl-36978149

ABSTRACT

BACKGROUND: Soil microorganisms are in constant interaction with plants, and these interactions shape the composition of soil bacterial communities by modifying their environment. However, little is known about the relationship between microorganisms and native plants present in extreme environments that are not affected by human intervention. Using high-throughput sequencing in combination with random forest and co-occurrence network analyses, we compared soil bacterial communities inhabiting the rhizosphere surrounding soil (RSS) and the corresponding bulk soil (BS) of 21 native plant species organized into three vegetation belts along the altitudinal gradient (2400-4500 m a.s.l.) of the Talabre-Lejía transect (TLT) in the slopes of the Andes in the Atacama Desert. We assessed how each plant community influenced the taxa, potential functions, and ecological interactions of the soil bacterial communities in this extreme natural ecosystem. We tested the ability of the stress gradient hypothesis, which predicts that positive species interactions become increasingly important as stressful conditions increase, to explain the interactions among members of TLT soil microbial communities. RESULTS: Our comparison of RSS and BS compartments along the TLT provided evidence of plant-specific microbial community composition in the RSS and showed that bacterial communities modify their ecological interactions, in particular, their positive:negative connection ratios in the presence of plant roots at each vegetation belt. We also identified the taxa driving the transition of the BS to the RSS, which appear to be indicators of key host-microbial relationships in the rhizosphere of plants in response to different abiotic conditions. Finally, the potential functions of the bacterial communities also diverge between the BS and the RSS compartments, particularly in the extreme and harshest belts of the TLT. CONCLUSIONS: In this study, we identified taxa of bacterial communities that establish species-specific relationships with native plants and showed that over a gradient of changing abiotic conditions, these relationships may also be plant community specific. These findings also reveal that the interactions among members of the soil microbial communities do not support the stress gradient hypothesis. However, through the RSS compartment, each plant community appears to moderate the abiotic stress gradient and increase the efficiency of the soil microbial community, suggesting that positive interactions may be context dependent.

SELECTION OF CITATIONS
SEARCH DETAIL