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OBJECTIVE: To evaluate the risk factors for lymph node metastasis (LNM) after a non-curative (NC) gastric endoscopic submucosal dissection (ESD) and to validate and eventually refine the eCura scoring system in the Western setting. Also, to assess the rate and risk factors for parietal residual disease. DESIGN: Retrospective multicentre multinational study of prospectively collected registries from 19 Western centres. Patients who had been submitted to surgery or had at least one follow-up endoscopy were included. The eCura system was applied to assess its accuracy in the Western setting, and a modified version was created according to the results (W-eCura score). The discriminative capacities of the eCura and W-eCura scores to predict LNM were assessed and compared. RESULTS: A total of 314 NC gastric ESDs were analysed (72% high-risk resection (HRR); 28% local-risk resection). Among HRR patients submitted to surgery, 25% had parietal disease and 15% had LNM in the surgical specimen. The risk of LNM was significantly different across the eCura groups (areas under the receiver operating characteristic curve (AUC-ROC) of 0.900 (95% CI 0.852 to 0.949)). The AUC-ROC of the W-eCura for LNM (0.916, 95% CI 0.870 to 0.961; p=0.012) was significantly higher compared with the original eCura. Positive vertical margin, lymphatic invasion and younger age were associated with a higher risk of parietal residual lesion in the surgical specimen. CONCLUSION: The eCura scoring system may be applied in Western countries to stratify the risk of LNM after a gastric HRR. A new score is proposed that may further decrease the number of unnecessary surgeries.
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Resección Endoscópica de la Mucosa , Neoplasias Gástricas , Humanos , Neoplasias Gástricas/cirugía , Neoplasias Gástricas/patología , Estudios Retrospectivos , Factores de Riesgo , Gastrectomía/métodos , Endoscopía Gastrointestinal , Mucosa Gástrica/cirugía , Mucosa Gástrica/patologíaRESUMEN
Pancreatic cancer surveillance can improve outcomes in high-risk individuals. However, little is known about its applicability and findings in routine clinical practice. Our aim was to evaluate findings on screening tests in high-risk individuals in a clinical practice setting and to analyze factors associated with the presence of relevant pancreatic lesions. We developed a prospective observational study of pancreatic cancer high risk patients that meet criteria of surveillance from the International Cancer of the Pancreas Screening Consortium. The demographic variables, other risk factors and imaging findings are collected. Patients with significant findings are compared to those without noteworthy findings. Of 70 high-risk individuals, 25 fitted the criteria for pancreatic cancer surveillance. The most frequent condition was hereditary breast and ovarian cancer syndrome (60%). We identified eleven abnormal imaging findings (44%) and three of them (12%) were relevant: two intraductal papillary mucinous neoplasms and one localized pancreatic neoplasm. BRCA2 mutation was more frequent in patients with significant lesions (66.7% vs 30%, p=0.376) but smoking and diabetes were not associated with relevant findings (0 vs 18 %, p=0.578 and 0 vs 4.5%, p=0.880 respectively). Screening test could detect early-stage or resectable lesions in a significant in a significant percentage of the selected high-risk population. The most relevant findings were in patients belonging to hereditary breast and ovarian cancer syndrome.
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Carcinoma Ductal Pancreático , Síndrome de Cáncer de Mama y Ovario Hereditario , Neoplasias Pancreáticas , Femenino , Humanos , Carcinoma Ductal Pancreático/diagnóstico , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patología , Detección Precoz del Cáncer/métodos , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/patología , Neoplasias PancreáticasRESUMEN
Vehicle-to-everything (V2X) communications enable real-time information exchange between vehicles and infrastructure, which extends the perception range of vehicles beyond the limits of on-board sensors and, thus, facilitating the realisation of cooperative, connected, and automated mobility (CCAM) services that will improve road safety and traffic efficiency. In the context of CCAM, the successful deployments of cooperative intelligent transport system (C-ITS) use cases, with the integration of advanced wireless communication technologies, are effectively leading to make transport safer and more efficient. However, the evaluation of multi-vendor and multi-protocol based CCAM service architectures can become challenging and complex. Additionally, conducting on-demand field trials of such architectures with real vehicles involved is prohibitively expensive and time-consuming. In order to overcome these obstacles, in this paper, we present the development of a standards-compliant experimental vehicular on-board unit (OBU) that supports the integration of multiple V2X protocols from different vendors to communicate with heterogeneous cloud-based services that are offered by several original equipment manufacturers (OEMs). We experimentally demonstrate the functionalities of the OBU in a real-world deployment of a cooperative collision avoidance service infrastructure that is based on edge and cloud servers. In addition, we measure end-to-end application-level latencies of multi-protocol supported V2X information flows to show the effectiveness of interoperability in V2X communications between different vehicle OEMs.
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A novel electrochemical disposable nucleic acid biosensor for simple, rapid, and specific detection of adulterations with horsemeat is reported in this work. The biosensing platform involves immobilization of a 40-mer RNA probe specific for a characteristic fragment of the mitochondrial DNA D-loop region of horse onto the surface of magnetic microcarriers. In addition, signal amplification was accomplished by using a commercial antibody specific to RNA/DNA duplexes and a bacterial protein conjugated with a horseradish peroxidase homopolymer (ProtA-HRP40). Amperometric detection at -0.20 V vs Ag pseudoreference electrode was carried out at disposable screen-printed carbon electrodes. The methodology achieved a limit of detection (LOD) of 0.12 pM (3.0 attomoles) for the synthetic target and showed ability to discriminate between raw beef and horsemeat using just 50 ng of total extracted mitochondrial DNA (â¼16â¯660 bp in length) without previous fragmentation. The biosensor also allowed discrimination between 100% raw beef and beef meat samples spiked with only 0.5% (w/w) horse meat (levels established by the European Commission) using raw mitochondrial lysates without DNA extraction or polymerase chain reaction (PCR) amplification in just 75 min. These interesting features made the developed methodology an extremely interesting tool for beef meat screening, and it can be easily adapted to the determination of other meat adulterations by selection of the appropriate specific fragments of the mitochondrial DNA region and capture probes.
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ADN Mitocondrial/química , Técnicas Electroquímicas/instrumentación , Carne/análisis , Reacción en Cadena de la Polimerasa/métodos , Reacción en Cadena de la Polimerasa/veterinaria , Animales , Bovinos , ADN Mitocondrial/genética , Equipos Desechables , Análisis de los Alimentos , Caballos , Reacción en Cadena de la Polimerasa/instrumentaciónRESUMEN
BACKGROUND: This paper studies the socioeconomic disparities in self-perceived oral health among Chilean adults and in the perceived physical, functional, psychological and social consequences of oral health. METHODS: In February 2011, 1,413 residents of Metropolitan Area of Santiago, Chile, were interviewed using a standardized questionnaire and examined by dentists for dental status and oral health conditions. Only adults 18 to 60 years old affiliated with the public healthcare system were eligible to participate. We estimate socioeconomic gradients in self-perceived oral health and its distinct dimensions. We use the Heckman two-step procedure to control for selection bias given the non-random nature of the sample. In addition, we use a two-equation ordered response model given the discrete nature of the dependent variable. RESULTS: There is a non-linear socioeconomic gradient in self-perceived oral health even after controlling for oral health status. The gradient is steep at the lower end of the income distribution and constant at mid-income levels. These socioeconomic disparities are also found for the psychological and social dimensions of self-perceived oral health, but not for the functional limitations and physical pain dimensions. CONCLUSIONS: The findings are consistent with inequities in the access to oral health services due to insufficient provision in the public sector and costly options in the private sector.
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Autoevaluación Diagnóstica , Disparidades en el Estado de Salud , Salud Bucal , Adolescente , Adulto , Chile , Atención a la Salud/organización & administración , Femenino , Humanos , Renta/estadística & datos numéricos , Masculino , Persona de Mediana Edad , Sector Público , Encuestas y Cuestionarios , Adulto JovenRESUMEN
In nature roots grow in the dark and away from light (negative phototropism). However, most current research in root biology has been carried out with the root system grown in the presence of light. Here, we have engineered a device, called Dark-Root (D-Root), to grow plants in vitro with the aerial part exposed to the normal light/dark photoperiod while the roots are in the dark or exposed to specific wavelengths or light intensities. D-Root provides an efficient system for cultivating a large number of seedlings and easily characterizing root architecture in the dark. At the morphological level, root illumination shortens root length and promotes early emergence of lateral roots, therefore inducing expansion of the root system. Surprisingly, root illumination also affects shoot development, including flowering time. Our analyses also show that root illumination alters the proper response to hormones or abiotic stress (e.g. salt or osmotic stress) and nutrient starvation, enhancing inhibition of root growth. In conclusion, D-Root provides a growing system closer to the natural one for assaying Arabidopsis plants, and therefore its use will contribute to a better understanding of the mechanisms involved in root development, hormonal signaling and stress responses.
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Oscuridad , Luz , Raíces de Plantas/crecimiento & desarrollo , Regulación de la Expresión Génica de las Plantas/genética , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Raíces de Plantas/fisiología , Raíces de Plantas/efectos de la radiaciónRESUMEN
Reservation frame slotted-ALOHA (RFSA) was proposed in the past to manage the access to the wireless channel when devices generate long messages fragmented into small packets. In this paper, we consider an M2M area network composed of end-devices that periodically respond to the requests from a gateway with the transmission of fragmented messages. The idle network is suddenly set into saturation, having all end-devices attempting to get access to the channel simultaneously. This has been referred to as delta traffic. While previous works analyze the throughput of RFSA in steady-state conditions, assuming that traffic is generated following random distributions, the performance of RFSA under delta traffic has never received attention. In this paper, we propose a theoretical model to calculate the average delay and energy consumption required to resolve the contention under delta traffic using RFSA.We have carried out computer-based simulations to validate the accuracy of the theoretical model and to compare the performance for RFSA and FSA. Results show that there is an optimal frame length that minimizes delay and energy consumption and which depends on the number of end-devices. In addition, it is shown that RFSA reduces the energy consumed per end-device by more than 50% with respect to FSA under delta traffic.
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Redes de Comunicación de Computadores , Telemetría , Tecnología Inalámbrica , Recolección de DatosRESUMEN
Recent standardization efforts on low-power wireless communication technologies, including time-slotted channel hopping (TSCH) and DASH7 Alliance Mode (D7AM), are starting to change industrial sensing applications, enabling networks to scale up to thousands of nodes whilst achieving high reliability. Past technologies, such as ZigBee, rooted in IEEE 802.15.4, and ISO 18000-7, rooted in frame-slotted ALOHA (FSA), are based on contention medium access control (MAC) layers and have very poor performance in dense networks, thus preventing the Internet of Things (IoT) paradigm from really taking off. Industrial sensing applications, such as those being deployed in oil refineries, have stringent requirements on data reliability and are being built using new standards. Despite the benefits of these new technologies, industrial shifts are not happening due to the enormous technology development and adoption costs and the fact that new standards are not well-known and completely understood. In this article, we provide a deep analysis of TSCH and D7AM, outlining operational and implementation details with the aim of facilitating the adoption of these technologies to sensor application developers.
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Data collection is a key scenario for the Internet of Things because it enables gathering sensor data from distributed nodes that use low-power and long-range wireless technologies to communicate in a single-hop approach. In this kind of scenario, the network is composed of one coordinator that covers a particular area and a large number of nodes, typically hundreds or thousands, that transmit data to the coordinator upon request. Considering this scenario, in this paper we experimentally validate the energy consumption of two Medium Access Control (MAC) protocols, Frame Slotted ALOHA (FSA) and Distributed Queuing (DQ). We model both protocols as a state machine and conduct experiments to measure the average energy consumption in each state and the average number of times that a node has to be in each state in order to transmit a data packet to the coordinator. The results show that FSA is more energy efficient than DQ if the number of nodes is known a priori because the number of slots per frame can be adjusted accordingly. However, in such scenarios the number of nodes cannot be easily anticipated, leading to additional packet collisions and a higher energy consumption due to retransmissions. Contrarily, DQ does not require to know the number of nodes in advance because it is able to efficiently construct an ad hoc network schedule for each collection round. This kind of a schedule ensures that there are no packet collisions during data transmission, thus leading to an energy consumption reduction above 10% compared to FSA.
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Redes de Comunicación de Computadores/instrumentación , Recolección de Datos/instrumentación , Recolección de Datos/métodos , Modelos Teóricos , Teoría de Sistemas , Tecnología Inalámbrica/instrumentaciónRESUMEN
OBJECTIVE: To analyze the change in the characteristics of presentation, evolution and treatment in the ICU, as well as the functional evolution at 12 months of spontaneous intracranial hemorrhages (ICHs) treated in an ICU reference center. PATIENT AND METHODS: Descriptive, retrospective study in a Neurocritical Reference Hospital. All admissions of patients with HICE during three periods are studied: 1999-2001 (I), 2015-2016 (II) and 2020-2021 (III). Evolution in the three periods of demographic variables, baseline characteristics of the patients, clinical variables and characteristics of bleeding, evolutionary data in the ICU are studied. At one year we assessed the GOS scale (Glasgow Outcome Score) according to whether they had a poor (GOS 1-3) or good (GOS 4-5) prognosis. RESULTS: 300 admitted patients, distributed in periods: I: 28.7%, II: 36.3% and III: 35%. 56.7% were males aged 66 (55.5-74) years; ICH score 2 (1-3). The ICU stay was 5 (2-14) days with a mortality of 36.8%. GOS 1-3 a year in 67.3% and GOS 4-5 in 32.7%. Comparing the three periods, we observed a higher prevalence in women, and the presence of cardiovascular factors; no changes in etiology; in relation to the location, it increases cerebellar hemorrhage and in the brainstem. Although the severity was greater, the stay in the ICU, the use of invasive mechanical ventilation and tracheostomy were lower. Open surgery has decreased its use by 50%. Mortality continues to be high, stagnating in the ICU at 35% and entails a high degree of disability one year after assessment. CONCLUSIONS: Severe ICH is a complex pathology that has changed some characteristics in the last two decades, with more severe patients, with more cardiovascular history and a greater predominance of brainstem and cerebellar hemorrhage. Despite the increase in severity, better parameters during the ICU stay, with open surgery used 50% less. Mortality remains stagnant at 35% with high disability per year.
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Hemorragia Cerebral , Escala de Consecuencias de Glasgow , Unidades de Cuidados Intensivos , Humanos , Masculino , Femenino , Anciano , Estudios Retrospectivos , Persona de Mediana Edad , Hemorragia Cerebral/etiología , Hemorragia Cerebral/cirugía , Hemorragia Cerebral/epidemiología , Pronóstico , Centros de Atención Terciaria , Tiempo de InternaciónRESUMEN
BACKGROUND: Idiopathic ventricular fibrillation (IVF) can be associated with undetected distinct conditions such as microstructural cardiomyopathic alterations (MiCM) or Purkinje (Purk) activities with structurally normal hearts. OBJECTIVE: This study sought to evaluate the characteristics of recurrent VF recorded on implantable defibrillator electrograms, associated with these substrates. METHODS: This was a multicenter collaboration study. At 32 centers, we selected patients with an initial diagnosis of IVF and recurrent arrhythmia at follow-up without antiarrhythmic drugs, in whom mapping demonstrated Purk or MiCM substrate. We analyzed variables related to previous ectopy, sinus rate preceding VF, trigger, and initial VF cycle lengths. Logistic regression with cross validation was used to evaluate the performance of criteria to discriminate Purk or MiCM substrates. RESULTS: Among 95 patients (35 women, age 35 ± 11 years) meeting the inclusion criteria, IVF was associated with MiCM in 41 and Purk in 54 patients. A total of 117 arrhythmia recurrences including 91% VF were recorded on defibrillator. Three variables were mostly discriminant. Sinus tachycardia (≤570 ms) was more frequent in MiCM (35.9% vs 13.4%, P = 0.014) whereas short-coupled (<350 ms) triggers were most frequent in Purk-related VF (95.5% vs 23.1%, P = 0.001), which also had shorter VFCLs (182 ± 15 ms vs 215 ± 24 ms, P < 0.001).The multivariable combination provided the highest prediction (accuracy = 0.93 ± 0.05, range 0.833-1.000), discriminating 81% of IVF substrates with a high probability (>80%). Ectopy were inconsistently present before VF. CONCLUSIONS: Characteristics of arrhythmia recurrences on implantable cardioverter- defibrillator provide phenotypic markers of the distinct and hidden substrates underlying IVF. These findings have significant clinical and genetic implications.
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Circum-Mediterranean firs are considered among the most drought-sensitive species to climate change. Understanding the genetic basis of trees' adaptive capacity and intra-specific variability to drought avoidance is mandatory to define conservation measures, thus potentially preventing their extinction. We focus here on Abies pinsapo and Abies marocana, both relict tree species, endemic from south Spain and north Morocco, respectively. A total of 607 samples were collected from eight nuclei: six from Spanish fir and two from Moroccan fir. A genotyping by sequencing technique called double digestion restriction site-associated DNA sequencing (ddRAD-seq) was performed to obtain a genetic matrix based on single-nucleotide polymorphisms (SNPs). This matrix was utilized to study the genetic structure of A. pinsapo populations and to carry out selection signature studies. In order to understand how Spanish fir and Moroccan fir cope with climate change, genotype-environment associations (GEAs) were identified. Further, the vulnerability of these species to climate variations was estimated by the risk of non-adaptedness (RONA). The filtering of the de novo assembly of A. pinsapo provided 3,982 SNPs from 504 out of 509 trees sequenced. Principal component analysis (PCA) genetically separated Grazalema from the rest of the Spanish populations. However, FST values showed significant differences among the sampling points. We found 51 loci potentially under selection. Homolog sequences were found for some proteins related to abiotic stress response, such as dehydration-responsive element binding transcription factor, regulation of abscisic acid signaling, and methylation pathway. A total of 15 associations with 11 different loci were observed in the GEA studies, with the maximum temperature of the warmest month being the variable with the highest number of associated loci. This temperature sensitivity was also supported by the risk of non-adaptedness, which yielded a higher risk for both A. pinsapo and A. marocana under the high emission scenario (Representative Concentration Pathway (RCP) 8.5). This study sheds light on the response to climate change of these two endemic species.
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OBJECTIVE: Herpes simplex virus type1 (HSV-1) reactivation have been described in patients with invasive mechanical ventilation and recently in patients with acute respiratory distress syndrome (ARDS) secondary to COVID-19 with higher rates of reactivation than were detected previously in critical care, and although the diagnosis of HSV-1 pneumonia is not easy, its presence is associate with an increase in morbidity and mortality. The objective of this study is to determinate if the identification of HSV-1 in lower airway of patients with ARDS secondary to COVID-19 have influence in clinical outcome and mortality. METHOD: Two hundred twenty-four admitted patients in intensive care unit (ICU) of Complejo Hospitalario Universitario de Toledo diagnosed of severe acute respiratory syndrome coronavirus2 (SARS-CoV-2) were reviewed and were selected those with mechanical ventilation who had undergone (BAL). It was registered all results of HSV-1 PCR (negative and positive). RESULTS: During the study period (November 28, 2020 to April 13, 2021) was admitted 224 patients in ICU diagnosed of SARS-CoV-2 pneumonia. Eighty-three patients of them had undergone BAL, with HSV-1 PCR positive result in 47 (56%), and negative result in 36 (43.4%). We performed pathological anatomy study in BAL samples on 26 of the total BAL realized. Typical cytopathic characteristics of HSV-1 were found in 13 samples (50%) and 11 of them (84.6%) have had HSV-1 PCR positive result. Thirty days mortality was significantly higher in the group of patients with HSV-1 PCR positive result (33.5% vs. 57.4%, P=.015). This difference was stronger in the group of patients with HSV-1 findings in the pathological anatomy study (30.8% vs. 69.2%, P=.047). CONCLUSION: Our results suggest that ARDS secondary to SARS-CoV-2 pneumonia is highly associated to HSV-1 reactivation and that the finding of HSV-1 in lower airway is associated with a worst prognostic and with significantly mortality increase. It is necessary to carry out more extensive studies to determinate if treatment with acyclovir can improve the prognosis of these patients.
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COVID-19 , Herpes Simple , Herpesvirus Humano 1 , Neumonía , Síndrome de Dificultad Respiratoria , Humanos , COVID-19/complicaciones , SARS-CoV-2 , Herpes Simple/complicaciones , Herpes Simple/diagnóstico , Herpes Simple/tratamiento farmacológico , Síndrome de Dificultad Respiratoria/etiología , Respiración ArtificialRESUMEN
Objective: Herpes simplex virus type 1 (HSV-1) reactivation have been described in patients with invasive mechanical ventilation and recently in patients with acute respiratory distress syndrome (ARDS) secondary to COVID-19 with higher rates of reactivation than were detected previously in critical care, and although the diagnosis of HSV-1 pneumonia is not easy, its presence is associate with an increase in morbidity and mortality. The objective of this study is to determinate if the identification of HSV-1 in lower airway of patients with ARDS secondary to COVID-19 have influence in clinical outcome and mortality. Method: Two hundred twenty-four admitted patients in intensive care unit (ICU) of Complejo Hospitalario Universitario de Toledo diagnosed of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were reviewed and were selected those with mechanical ventilation who had undergone (BAL). It was registered all results of HSV-1 PCR (negative and positive). Results: During the study period (November 28, 2020 to April 13, 2021) was admitted 224 patients in ICU diagnosed of SARS-CoV-2 pneumonia. Eighty-three patients of them had undergone BAL, with HSV-1 PCR positive result in 47 (56%), and negative result in 36 (43.4%). We performed pathological anatomy study in BAL samples on 26 of the total BAL realized. Typical cytopathic characteristics of HSV-1 were found in 13 samples (50%) and 11 of them (84.6%) have had HSV-1 PCR positive result. Thirty days mortality was significantly higher in the group of patients with HSV-1 PCR positive result (33.5% vs. 57.4%, pâ¯=â¯0.015). This difference was stronger in the group of patients with HSV-1 findings in the pathological anatomy study (30.8% vs. 69.2%, pâ¯=â¯0.047). Conclusion: Our results suggest that ARDS secondary to SARS-CoV-2 pneumonia is highly associated to HSV-1 reactivation and that the finding of HSV-1 in lower airway is associated with a worst prognostic and with significantly mortality increase. It is necessary to carry out more extensive studies to determinate if treatment with acyclovir can improve the prognosis of these patients.
Objetivo: Las reactivaciones del virus herpes simple (VHS) están descritas en los pacientes en ventilación mecánica invasiva y recientemente en el síndrome de distrés respiratorio agudo (SDRA) por COVID-19, con tasas más altas que las descritas previamente en pacientes críticos, y aunque el diagnóstico de neumonía por VHS es difícil, su presencia se asocia con aumento de la morbimortalidad. El objetivo de este estudio es determinar si la identificación de VHS en el tracto respiratorio inferior en pacientes en ventilación mecánica con SDRA por COVID-19 influye sobre la evolución clínica y la mortalidad. Método: Se revisaron 224 pacientes ingresados en el servicio de medicina intensiva del Complejo Hospitalario de Toledo con el diagnóstico de neumonía por SARS-CoV-2 y se seleccionaron los pacientes en ventilación mecánica a los que se les había realizado lavado broncoalveolar (LBA). Se registraron todos los resultados de la PCR, tanto si fue positiva como si fue negativa para VHS. Resultados: Durante el periodo de estudio (del 28 de noviembre de 2020 hasta el 13 de abril de 2021) ingresaron 224 pacientes en la UCI con el diagnóstico de neumonía por SARS-CoV-2. De ellos, en 83 se realizó lavado broncoalveolar (LBA), siendo la PCR para VHS-1 positiva en 47 y negativa en 36 (56,6%). Realizamos estudio anatomopatológico en muestras de LBA a 26 pacientes del total de la muestra. Se encontraron características citopáticas típicas de infección por herpes en 13 (50%), de los cuales 11 (84,6%) tenían PCR positiva. La mortalidad a los 30 días fue significativamente mayor en el grupo de pacientes con PCR positiva (33,5% vs 57,4%, pâ¯=â¯0,015). Esta diferencia fue aún más marcada en el grupo con hallazgos anatomopatológicos compatibles con neumonía por VHS (30,8% versus 69,2%, pâ¯=â¯0,047). Conclusión: Nuestros resultados sugieren que el SDRA secundario a neumonía por SARS-CoV-2 se asocia a una alta reactivación del VHS y que su hallazgo en el tracto respiratorio inferior se asocia con un peor pronóstico y un aumento significativo de la mortalidad. Son necesarios estudios más amplios para determinar si el tratamiento con aciclovir puede mejorar el pronóstico de estos pacientes.
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The frequency and intensity of drought events are increasing worldwide, challenging the adaptive capacity of several tree species. Here, we evaluate tree growth patterns and climate sensitivity to precipitation, temperature, and drought in the relict Moroccan fir Abies marocana. We selected two study sites, formerly stated as harboring contrasting A. marocana taxa (A. marocana and A. tazaotana, respectively). For each tree, dendrochronological methods were applied to quantify growth patterns and climate-growth sensitivity. Further, ddRAD-seq was performed on the same trees and close saplings to obtain single nucleotide polymorphisms (SNPs) and related genotype-phenotype associations. Genetic differentiation between the two studied remnant populations of A. marocana was weak. Growth patterns and climate-growth relationships were almost similar at the two sites studied, supporting a negative effect of warming. Growth trends and tree size showed associations with SNPs, although there were no relationships with phenotypes related to climatic sensitivity. We found significant differences in the SNPs subjected to selection in the saplings compared to the old trees, suggesting that relict tree populations might be subjected to genetic differentiation and local adaptation to climate dryness. Our results illustrate the potential of tree rings and genome-wide analysis to improve our understanding of the adaptive capacity of drought-sensitive forests to cope with ongoing climate change.
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Local differentiation at distribution limits may influence species' adaptive capacity to environmental changes. However, drivers, such gene flow and local selection, are still poorly understood. We focus on the role played by range limits in mountain forests to test the hypothesis that relict tree populations are subjected to genetic differentiation and local adaptation. Two alpine treelines of mountain pine (Pinus uncinata Ram. ex DC) were investigated in the Spanish Pyrenees. Further, an isolated relict population forming the species' southernmost distribution limit in north-eastern Spain was also investigated. Using genotyping by sequencing, a genetic matrix conformed by single nucleotide polymorphisms (SNPs) was obtained. This matrix was used to perform genotype-environment and genotype-phenotype associations, as well as to model risk of non-adaptedness. Increasing climate seasonality appears as an essential element in the interpretation of SNPs subjected to selective pressures. Genetic differentiations were overall weak. The differences in leaf mass area and radial growth rate, as well as the identification of several SNPs subjected to selective pressures, exceeded neutral predictions of differentiation among populations. Despite genetic drift might prevail in the isolated population, the Fst values (0.060 and 0.066) showed a moderate genetic drift and Nm values (3.939 and 3.555) indicate the presence of gene flow between the relict population and both treelines. Nonetheless, the SNPs subjected to selection pressures provide evidences of possible selection in treeline ecotones. Persistence in range boundaries seems to involve several selective pressures in species' traits, which were significantly related to enhanced drought seasonality at the limit of P. uncinata distribution range. We conclude that gene flow is unlikely to constrain adaptation in the P. uncinata rear edge, although this species shows vulnerability to future climate change scenarios involving warmer and drier conditions.
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Pinus , España , Pinus/genética , Árboles , Bosques , Cambio Climático , Flujo GenéticoRESUMEN
Ongoing climatic change is threatening the survival of drought-sensitive tree species, such as silver fir (Abies alba). Drought-induced dieback had been previously explored in this conifer, although the role played by tree-level genetic diversity and its relationship with growth patterns and soil microsite conditions remained elusive. We used double digest restriction-site-associated DNA sequencing (ddRADseq) to describe different genetic characteristics of five silver fir forests in the Spanish Pyrenees, including declining and non-declining trees. Single nucleotide polymorphisms (SNPs) were used to investigate the relationships between genetics, dieback, intraspecific trait variation (functional dendrophenotypic traits and leaf traits), local bioclimatic conditions, and rhizosphere soil properties. While there were no noticeable genetic differences between declining and non-declining trees, genome-environment associations with selection signatures were abundant, suggesting a strong influence of climate, soil physicochemical properties, and soil microbial diversity on local adaptation. These results provide novel insights into how genetics and diverse environmental factors are interrelated and highlight the need to incorporate genetic data into silver fir forest dieback studies to gain a better understanding of local adaptation.
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Introduction: Understanding the adaptive capacity to current climate change of drought-sensitive tree species is mandatory, given their limited prospect of migration and adaptation as long-lived, sessile organisms. Knowledge about the molecular and eco-physiological mechanisms that control drought resilience is thus key, since water shortage appears as one of the main abiotic factors threatening forests ecosystems. However, our current background is scarce, especially in conifers, due to their huge and complex genomes. Methods: Here we investigated the eco-physiological and transcriptomic basis of drought response of the climate change-threatened conifer Cedrus atlantica. We studied C. atlantica seedlings from two locations with contrasting drought conditions to investigate a local adaptation. Seedlings were subjected to experimental drought conditions, and were monitored at immediate (24 hours) and extended (20 days) times. In addition, post-drought recovery was investigated, depicting two contrasting responses in both locations (drought resilient and non-resilient). Single nucleotide polymorphisms (SNPs) were also studied to characterize the genomic basis of drought resilience and investigate a rapid local adaptation of C. atlantica. Results: De novo transcriptome assembly was performed for the first time in this species, providing differences in gene expression between the immediate and extended treatments, as well as among the post-drought recovery phenotypes. Weighted gene co-expression network analysis showed a regulation of stomatal closing and photosynthetic activity during the immediate drought, consistent with an isohydric dynamic. During the extended drought, growth and flavonoid biosynthesis inhibition mechanisms prevailed, probably to increase root-to-shoot ratio and to limit the energy-intensive biosynthesis of secondary metabolites. Drought sensitive individuals failed in metabolism and photosynthesis regulation under drought stress, and in limiting secondary metabolite production. Moreover, genomic differences (SNPs) were found between drought resilient and sensitive seedlings, and between the two studied locations, which were mostly related to transposable elements. Discussion: This work provides novel insights into the transcriptomic basis of drought response of C. atlantica, a set of candidate genes mechanistically involved in its drought sensitivity and evidence of a rapid local adaptation. Our results may help guide conservation programs for this threatened conifer, contribute to advance drought-resilience research and shed light on trees' adaptive potential to current climate change.