Mortality-Associated Factors in a Traumatic Brain Injury Population in Mexico.

BACKGROUND: Traumatic brain injury (TBI) is a major cause of death and disability, with a rising incidence in recent years. Factors such as age, sex, hypotension, low score on the Glasgow Coma Scale, use of invasive mechanical ventilation and vasopressors, etc., have been associated with mortality caused by TBI. The aim of this study was to identify the clinical and sociodemographic characteristics that influence the mortality or survival of patients with TBI in a tertiary care hospital in Mexico. METHODS: A sample of 94 patients aged 18 years or older, from both sexes, with an admitting diagnosis of mild-to-severe head trauma, with initial prehospital treatment, was taken. Data were extracted from the Single Registry of Patients with TBI at the Ixtapaluca Regional High Specialty Hospital (HRAEI). Normality tests were used to decide on the corresponding statistical analysis. RESULTS: No factors associated with mortality were found; however, survival analysis showed that the presence of seizures, aggregate limb trauma, and subjects with diabetes mellitus, heart disease or patients with four concomitant comorbidities had 100% mortality. In addition, having seizures in the prehospital setting increased the risk of mortality four times. Although they did not have a direct association with mortality, they significantly decreased survival. A larger sample size is probably required to obtain an association with mortality. CONCLUSIONS: These results reflect the severity of the clinical situation in this population and, although no risk factors were identified, they enlighten us about the conditions presented by patients who died.

The first genome-wide association study in the Argentinian and Chilean populations identifies shared genetics with Europeans in Alzheimer's disease.

INTRODUCTION: Genome-wide association studies (GWAS) are fundamental for identifying loci associated with diseases. However, they require replication in other ethnicities. METHODS: We performed GWAS on sporadic Alzheimer's disease (AD) including 539 patients and 854 controls from Argentina and Chile. We combined our results with those from the European Alzheimer and Dementia Biobank (EADB) in a meta-analysis and tested their genetic risk score (GRS) performance in this admixed population. RESULTS: We detected apolipoprotein E ε4 as the single genome-wide significant signal (odds ratio  = 2.93 [2.37-3.63], P = 2.6 × 10-23 ). The meta-analysis with EADB summary statistics revealed four new loci reaching GWAS significance. Functional annotations of these loci implicated endosome/lysosomal function. Finally, the AD-GRS presented a similar performance in these populations, despite the score diminished when the Native American ancestry rose. DISCUSSION: We report the first GWAS on AD in a population from South America. It shows shared genetics modulating AD risk between the European and these admixed populations. HIGHLIGHTS: This is the first genome-wide association study on Alzheimer's disease (AD) in a population sample from Argentina and Chile. Trans-ethnic meta-analysis reveals four new loci involving lysosomal function in AD. This is the first independent replication for TREM2L, IGH-gene-cluster, and ADAM17 loci. A genetic risk score (GRS) developed in Europeans performed well in this population. The higher the Native American ancestry the lower the GRS values.

Mortality and Survival Factors in Patients with Moderate and Severe Pneumonia Due to COVID-19.

During the pandemic, some mortality-related factors were age, sex, comorbidities (obesity, diabetes mellitus, and hypertension), recovery time, hospitalizations, and biochemical markers. The present work aimed to identify the mortality and survival factors in adults with moderate and severe pneumonia due to COVID-19 during the first and second waves of the pandemic in Mexico at a third-level hospital (High-Specialty Regional Hospital of Ixtapaluca (HRAEI), Ixtapaluca, Estado de Mexico, Mexico). A database was generated using information from the electronic clinical records of patients hospitalized from December 2021 to August 2022. Survival analysis was performed associating age, sex, longer recovery times, and some drugs. The risk factors found were age in the patients between 40 and 60 years (OR = 1.70), male sex (OR = 1.53), the presence of comorbidities (OR = 1.66) and hypertension (OR = 2.19), work occupation (construction workers OR = 5.22, factory workers OR = 3.13, unemployed OR = 2.93), the prehospital use of metamizole sodium (OR = 2.17), cough (OR = 1.73), and in-hospital oxygen therapy (reservoir mask OR = 6.6). The survival factors found in this study were working in the healthcare field (OR = 0.26), the prehospital use of certain medications (paracetamol OR = 0.65, dexamethasone OR = 0.55, and azithromycin OR = 0.47), presenting ageusia (OR = 0.5) and hyporexia (OR = 0.34), and the time using in-hospital oxygen therapy (device 1 OR = 0.72). Prehospital treatment needs to be reevaluated as dexamethasone and azithromycin proved to be protective factors. Likewise, providing aggressive oxygen therapy during hospital admission decreased mortality risk.

Cierre primario diferido en pacientes laparotomizados de emergencia con índice SENIC ≥ 3 puntos / Deferred primary closure in emergency laparotomized patients with SENIC index ≥ 3 points

Las infecciones del sitio operatorio representan un desafío en el entorno hospitalario. El cierre primario diferido ha surgido como técnica para prevenirlas. Esta investigación busca explorar los beneficios del cierre primario diferido en la reducción de infecciones, estancia hospitalaria y costos, mejorando los resultados clínicos en cirugías abdominales. Objetivos. Evaluar el cierre primario diferido en pacientes laparotomizados de emergencia que acuden Hospital Universitario de Mérida ­Venezuela, con índice SENIC ≥ 3 puntos. Métodos. Se llevó a cabo un estudio experimental prospectivo para evaluar los efectos del cierre primario diferido en comparación con el cierre primario en laparotomías exploradoras. La muestra consistió en 160 pacientes. Se analizaron la presencia de infecciones, la duración de la estancia hospitalaria y la evolución temporal de las infecciones como desenlaces del estudio. Resultados. Se encontró que el cierre primario diferido redujo la presencia de infecciones en comparación con el cierre primario. La limpieza trans-operatoria y el diagnóstico de abdomen agudo quirúrgico infeccioso fueron factores beneficiosos. La antibioticoterapia continua en el postoperatorio también fue más efectiva. Se observó una disminución del riesgo de infección en el grupo experimental en un 37% en comparación con el grupo de control. Conclusiones. El cierre primario diferido de la herida reduce significativamente la probabilidad de infección del sitio operatorio en cirugías abdominales con heridas contaminadas. Es una técnica beneficiosa para pacientes con abdomen agudo quirúrgico infeccioso. Además, el cierre primario diferido resulta rentable al disminuir tanto la incidencia de ISO como la duración de la estancia hospitalaria

Surgical site infections pose a challenge in the hospital setting. Delayed primary closure has emerged as a technique to prevent such infections. This research aims to explore the benefits of delayed primary closure in reducing infections, hospital stay, and costs, thus improving clinical outcomes in abdominal surgeries. Objectives. To evaluate delayed primary closure in emergency laparotomized patients with SENIC index ≥ 3 points at the University Hospital of Mérida, Venezuela. Methods. A prospective experimental study was conducted to assess the effects of delayed primary closure compared to primary closure in exploratory laparotomies. The sample consisted of 160 patients. The presence of infections, duration of hospital stay, and temporal evolution of infections were analyzed as study outcomes. Results. Delayed primary closure was found to reduce the presence of infections compared to primary closure. Transoperative cleaning and the diagnosis of infectious surgical acute abdomen were beneficial factors. Continuous postoperative antibiotic therapy was also more effective. A 37% reduction in the risk of infection was observed in the experimental group compared to the control group. Conclusions. Delayed primary closure significantly reduces the probability of surgical site infection in abdominal surgeries with contaminated wounds. It is a beneficial technique for patients with infectious surgical acute abdomen. Additionally, delayed primary closure proves cost-effective by reducing both the incidence of surgical site infections and the duration of hospital stay(AU)

Synergistic influence of cytokine gene polymorphisms over the risk of dementia: A multifactor dimensionality reduction analysis.

Objective: Evidence supports the important role of neuroinflammation in some types of dementia. This study aimed to evaluate the effect of epistasis of gene cytokines such as interleukin (IL)-α, IL-6, tumor necrosis factor (TNFα), and interferon-gamma (IFN-γ) on the susceptibility to the development of dementia. Materials and methods: In the study, 221 patients diagnosed with dementia and 710 controls were included. The multifactor-dimensionality reduction (MDR) analysis was performed to identify the epistasis between SNP located in genes of IL-α (rs1800587), IL-6 (rs1800796), TNFα (rs361525 and rs1800629), and IFNγ (rs2069705). The best risk prediction model was identified based on precision and cross-validation consistency. Results: Multifactor-dimensionality reduction analysis detected a significant model with the genes TNFα, IFNγ, IL1α, and IL6 (prediction success: 72%, p < 0.0001). When risk factors were analyzed with these polymorphisms, the model achieved a similar prediction for dementia as the genes-only model. Conclusion: These data indicate that gene-gene interactions form significant models to identify populations susceptible to dementia.

Predicted landscape of RETINOBLASTOMA-RELATED LxCxE-mediated interactions across the Chloroplastida.

The colonization of land by a single streptophyte algae lineage some 450 million years ago has been linked to multiple key innovations such as three-dimensional growth, alternation of generations, the presence of stomata, as well as innovations inherent to the birth of major plant lineages, such as the origins of vascular tissues, roots, seeds and flowers. Multicellularity, which evolved multiple times in the Chloroplastida coupled with precise spatiotemporal control of proliferation and differentiation were instrumental for the evolution of these traits. RETINOBLASTOMA-RELATED (RBR), the plant homolog of the metazoan Retinoblastoma protein (pRB), is a highly conserved and multifunctional core cell cycle regulator that has been implicated in the evolution of multicellularity in the green lineage as well as in plant multicellularity-related processes such as proliferation, differentiation, stem cell regulation and asymmetric cell division. RBR fulfills these roles through context-specific protein-protein interactions with proteins containing the Leu-x-Cys-x-Glu (LxCxE) short-linear motif (SLiM); however, how RBR-LxCxE interactions have changed throughout major innovations in the Viridiplantae kingdom is a question that remains unexplored. Here, we employ an in silico evo-devo approach to predict and analyze potential RBR-LxCxE interactions in different representative species of key Chloroplastida lineages, providing a valuable resource for deciphering RBR-LxCxE multiple functions. Furthermore, our analyses suggest that RBR-LxCxE interactions are an important component of RBR functions and that interactions with chromatin modifiers/remodelers, DNA replication and repair machinery are highly conserved throughout the Viridiplantae, while LxCxE interactions with transcriptional regulators likely diversified throughout the water-to-land transition.

Transcriptional analysis of Ceratopteris richardii young sporophyte reveals conservation of stem cell factors in the root apical meristem.

Gene expression in roots has been assessed in different plant species in studies ranging from complete organs to specific cell layers, and more recently at the single cell level. While certain genes or functional categories are expressed in the root of all or most plant species, lineage-specific genes have also been discovered. An increasing amount of transcriptomic data is available for angiosperms, while a limited amount of data is available for ferns, and few studies have focused on fern roots. Here, we present a de novo transcriptome assembly from three different parts of the Ceratopteris richardii young sporophyte. Differential gene expression analysis of the root tip transcriptional program showed an enrichment of functional categories related to histogenesis and cell division, indicating an active apical meristem. Analysis of a diverse set of orthologous genes revealed conserved expression in the root meristem, suggesting a preserved role for different developmental roles in this tissue, including stem cell maintenance. The reconstruction of evolutionary trajectories for ground tissue specification genes suggests a high degree of conservation in vascular plants, but not for genes involved in root cap development, showing that certain genes are absent in Ceratopteris or have intricate evolutionary paths difficult to track. Overall, our results suggest different processes of conservation and divergence of genes involved in root development.

Evidence of requirement for homologous-mediated DNA repair during Ambystoma mexicanum limb regeneration.

BACKGROUND: Limb regeneration in the axolotl is achieved by epimorphosis, thus depending on the blastema formation, a mass of progenitor cells capable of proliferating and differentiating to recover all lost structures functionally. During regeneration, the blastema cells accelerate the cell cycle and duplicate its genome, which is inherently difficult to replicate because of its length and composition, thus being prone to suffer double-strand breaks. RESULTS: We identified and characterized two remarkable components of the homologous recombination repair pathway (Amex.RAD51 and Amex.MRE11), which were heterologously expressed, biochemically characterized, and inhibited by specific chemicals. These same inhibitors were applied at different time points after amputation to study their effects during limb regeneration. We observed an increase in cellular senescent accompanied by a slight delay in regeneration at 28 days postamputation regenerated tissues; moreover, inhibitors caused a rise in the double-strand break signaling as a response to the inhibition of the repair mechanisms. CONCLUSIONS: We confirmed the participation and importance of homologous recombination during limb regeneration. The chemical inhibition induces double-strand breaks that lead to DNA damage associated senescence, or in an alternatively way, this damage could be possibly repaired by a different DNA repair pathway, permitting proper regeneration and avoiding senescence.

Nicotinamide as potential biomarker for Alzheimer's disease: A translational study based on metabolomics.

Introduction: The metabolic routes altered in Alzheimer's disease (AD) brain are poorly understood. As the metabolic pathways are evolutionarily conserved, the metabolic profiles carried out in animal models of AD could be directly translated into human studies. Methods: We performed untargeted Nuclear Magnetic Resonance metabolomics in hippocampus of McGill-R-Thy1-APP transgenic (Tg) rats, a model of AD-like cerebral amyloidosis and the translational potential of these findings was assessed by targeted Gas Chromatography-Electron Impact-Mass Spectrometry in plasma of participants in the German longitudinal cohort AgeCoDe. Results: In rat hippocampus 26 metabolites were identified. Of these 26 metabolites, nine showed differences between rat genotypes that were nominally significant. Two of them presented partial least square-discriminant analysis (PLS-DA) loadings with the larger absolute weights and the highest Variable Importance in Projection (VIP) scores and were specifically assigned to nicotinamide adenine dinucleotide (NAD) and nicotinamide (Nam). NAD levels were significantly decreased in Tg rat brains as compared to controls. In agreement with these results, plasma of AD patients showed significantly reduced levels of Nam in respect to cognitively normal participants. In addition, high plasma levels of Nam showed a 27% risk reduction of progressing to AD dementia within the following 2.5 years, this hazard ratio is lost afterwards. Discussion: To our knowledge, this is the first report showing that a decrease of Nam plasma levels is observed couple of years before conversion to AD, thereby suggesting its potential use as biomarker for AD progression.

Arabidopsis thaliana PrimPol is a primase and lesion bypass DNA polymerase with the biochemical characteristics to cope with DNA damage in the nucleus, mitochondria, and chloroplast.

PrimPol is a novel Primase-Polymerase that synthesizes RNA and DNA primers de novo and extents from these primers as a DNA polymerase. Animal PrimPol is involved in nuclear and mitochondrial DNA replication by virtue of its translesion DNA synthesis (TLS) and repriming activities. Here we report that the plant model Arabidopsis thaliana encodes a functional PrimPol (AtPrimPol). AtPrimPol is a low fidelity and a TLS polymerase capable to bypass DNA lesions, like thymine glycol and abasic sites, by incorporating directly across these lesions or by skipping them. AtPrimPol is also an efficient primase that preferentially recognizes the single-stranded 3'-GTCG-5' DNA sequence, where the 3'-G is cryptic. AtPrimPol is the first DNA polymerase that localizes in three cellular compartments: nucleus, mitochondria, and chloroplast. In vitro, AtPrimPol synthesizes primers that are extended by the plant organellar DNA polymerases and this reaction is regulated by organellar single-stranded binding proteins. Given the constant exposure of plants to endogenous and exogenous DNA-damaging agents and the enzymatic capabilities of lesion bypass and re-priming of AtPrimPol, we postulate a predominant role of this enzyme in avoiding replication fork collapse in all three plant genomes, both as a primase and as a TLS polymerase.

DNA repair during regeneration in Ambystoma mexicanum.

The remarkable regenerative capabilities of the salamander Ambystoma mexicanum have turned it into one of the principal models to study limb regeneration. During this process, a mass of low differentiated and highly proliferative cells, called blastema, propagates to reestablish the lost tissue in an accelerated way. Such a process implies the replication of a huge genome, 10 times larger than humans, with about 65.6% of repetitive sequences. These features make the axolotl genome inherently difficult to replicate and prone to bear mutations. In this context, the role of DNA repair mechanisms acquires great relevance to maintain genomic stability, especially if we consider the necessity of ensuring the correct replication and integrity of such a large genome in the blastema cells, which are key for tissue regeneration. On the contrary, DNA damage accumulation in these cells may result in senescence, apoptosis and premature differentiation, all of them are mechanisms employed to avoid DNA damage perpetuation but with the potential to affect the limb regeneration process. Here we review and discuss the current knowledge on the implications of DNA damage responses during salamander regeneration.

Síndrome de bouveret, una forma infrecuente de íleo biliar: a propósito de un caso y revisión de la literatura / Bouveret syndrome, a rare presentation of biliary ileus: case report and literature review

El íleo biliar es una complicación poco frecuente de la colelitiasis o colecistitis litiásica, aparece en menos del 1-3% de los pacientes con estas enfermedades, se define como una obstrucción intestinal mecánica debido a la impactación de uno o más cálculos biliares dentro del tracto gastrointestinal. Ubicaciones menos comunes incluyen estómago y duodeno (síndrome de Bouveret) y el colon. El diagnóstico del síndrome de Bouveret (SB) suele iniciar con una radiografía simple de abdomen; la ecografía abdominal confirma el síndrome de Bouveret si revela neumobilia y ubicación ectópica del cálculo biliar, sin embargo, en la mayoría de los casos se necesita una tomografía computarizada que permite una evaluación completa.Caso Clínico : Se presenta caso de masculino de 57 años de edad quien 8 días previo a su ingreso presenta dolor abdominal en epigastrio de moderada intensidad acompañado de pirosis, halitosis, náuseas, vómitos, intolerancia a la vía oral y ausencia de evacuaciones; acude inicialmente a gastroenterólogo que realiza endoscopia digestiva superior encontrando una imagen de obstrucción a nivel de primera porción de duodeno, motivo por el cual refiere a servicio de cirugía general donde es intervenido quirúrgicamente, se diagnostica el SB realizando gastrotomía, extracción del lito y piloroplastia, presentando adecuada evolución postoperatoria.Conclusión : El SB es un diagnóstico raro que afecta a <0,5% de los pacientes con cálculos biliares por lo que requiere un grado extremadamente alto de sospecha para el diagnóstico y puede observarse de manera incidental en estudios de imágenes en pacientes que presentan síntomas de obstrucción del vaciamiento gástrico(AU)

Biliary ileus is a rare complication of cholelithiasis or lithiasic cholecystitis, appearing in less than 1 to 3% of patients with these diseases, it is a mechanical intestinal obstruction due to the impaction of one or more gallstones within the gastrointestinal tract. Less common locations include the stomach and duodenum (Bouveret syndrome) and the colon. For the diagnosis of Bouveret's syndrome (BS) the initial step is usually a simple abdominal X-ray, while an abdominal ultrasound confirms Bouveret's syndrome if it reveals pneumobilia and ectopic location of the gallstone, in most cases a computed tomography (CT) scan is needed for diagnosis and full evaluation.Clinical Case: We present the clinical case of a 57-year-old male who 8 days prior to his admission presented with moderate intensity abdominal pain in the epigastrium accompanied by heartburn, halitosis, nausea, vomiting, intolerance to oral intake, and absence of evacuations; initially went to a gastroenterologist who performed upper digestive endoscopy, finding an image of obstruction at the level of the first portion of the duodenum, which is why he refers to the general surgery department where he underwent surgery, diagnosing BS by performing gastrotomy, stone extraction, and pyloroplasty, presenting adequate postoperative evolution.Conclusion : BS is a rare diagnosis that affects <0.5% of patients with gallstones and therefore requires an extremely high degree of suspicion for the diagnosis and can be seen incidentally on imaging studies in patients with symptoms of obstruction of gastric emptying(AU)

Experiencia en el manejo del tumor sólido pseudopapilar de pancreas en un centro de referencia / Experience in the management of the solid pseudopapillary tumor of the pancreas in a reference center

El tumor sólido pseudopapilar de páncreas tiene una incidencia de 0,13-2,7%, afectando preferentemente a mujeres jóvenes. Presentamos la experiencia en el manejo de tumores sólidos pseudopapilares de páncreas durante 10 años en el Hospital Coromoto de Maracaibo. Métodos: Estudio retrospectivo realizado en el Hospital Coromoto de Maracaibo desde enero 2010 hasta diciembre 2019. Se analizaron las variables edad, sexo, ubicación del tumor, procedimiento quirúrgico, tamaño del tumor, tiempo quirúrgico, tiempo de hospitalización y complicaciones. Resultados: De 183 casos totales de cirugía pancreática,15 casos presentaron diagnóstico anatomopatológico de tumor sólido pseudopapilar, representando un 8,20% del total de las cirugías pancreáticas; con edades comprendidas entre 15 a 56 años, con una media de 27,93 de los cuales el 93,33% fueron del género femenino. La ubicación más frecuente fue el cuerpo y la cola del páncreas con un 53,33%. El procedimiento quirúrgico más empleado fue la pancreatectomía distal en 8 casos. El tamaño promedio de los tumores fue de 6,47cm y el tiempo quirúrgico empleado fue de 254 minutos para las pancreatectomías distales y 412 minutos para los procedimientos de Whipple, con una media de hospitalización de 4,6 y 7,2 días respectivamente. Presentaron complicaciones 2 pacientes y sin decesos. Conclusiones: El tumor sólido pseudopapilar es una neoplasia pancreática de comportamiento incierto, con una baja incidencia entre todos los tumores de páncreas, donde la laparoscopia es un método de abordaje seguro en las pancreatectomías distales, sin diferencias en estancia hospitalaria y tiempo quirúrgico. La resección quirúrgica con márgenes libres es curativa(AU)

The solid pseudopapillary tumor of the pancreas has an incidence of 0.13-2.7%, preferentially affecting young women. We present the experience in the management of solid pseudopapillary tumors of the pancreas for 10 years at the Coromoto Hospital in Maracaibo. Methods: Retrospective study carried out at the Coromoto Hospital in Maracaibo from January 2010 to December 2019. The variables age, sex, tumor location, surgical procedure, tumor size, surgical time, hospitalization time and complications were analyzed. Results: Of 183 total cases of pancreatic surgery, 15 cases had a pathological diagnosis of a solid pseudopapillary tumor, representing 8.20% of the total of pancreatic surgeries; with ages ranging from 15 to 56 years, with an average of 27.93 of which 93.33% were female. The most frequent location was the body and tail of the pancreas with 53.33%. The most used surgical procedure was distal pancreatectomy in 8 cases. The average size of the tumors was 6.47cm and the surgical time used was 254 minutes for distal pancreatectomies and 412 minutes for Whipple procedures, with a mean hospital stay of 4.6 and 7.2 days, respectively. Two patients presented complications and no deaths. Conclusions: The solid pseudopapillary tumor is a pancreatic neoplasm of uncertain behavior, with a low incidence among all pancreatic tumors, where laparoscopy is a safe approach to distal pancreatectomies, without differences in hospital stay and surgical time. Surgical resection with free margins is curative(AU)

Functional Characterization of the Lin28/let-7 Circuit During Forelimb Regeneration in Ambystoma mexicanum and Its Influence on Metabolic Reprogramming.

The axolotl (Ambystoma mexicanum) is a caudate amphibian, which has an extraordinary ability to restore a wide variety of damaged structures by a process denominated epimorphosis. While the origin and potentiality of progenitor cells that take part during epimorphic regeneration are known to some extent, the metabolic changes experienced and their associated implications, remain unexplored. However, a circuit with a potential role as a modulator of cellular metabolism along regeneration is that formed by Lin28/let-7. In this study, we report two Lin28 paralogs and eight mature let-7 microRNAs encoded in the axolotl genome. Particularly, in the proliferative blastema stage amxLin28B is more abundant in the nuclei of blastemal cells, while the microRNAs amx-let-7c and amx-let-7a are most downregulated. Functional inhibition of Lin28 factors increase the levels of most mature let-7 microRNAs, consistent with an increment of intermediary metabolites of the Krebs cycle, and phenotypic alterations in the outgrowth of the blastema. In summary, we describe the primary components of the Lin28/let-7 circuit and their function during axolotl regeneration, acting upstream of metabolic reprogramming events.

Development and Cell Cycle Activity of the Root Apical Meristem in the Fern Ceratopteris richardii.

Ferns are a representative clade in plant evolution although underestimated in the genomic era. Ceratopteris richardii is an emergent model for developmental processes in ferns, yet a complete scheme of the different growth stages is necessary. Here, we present a developmental analysis, at the tissue and cellular levels, of the first shoot-borne root of Ceratopteris. We followed early stages and emergence of the root meristem in sporelings. While assessing root growth, the first shoot-borne root ceases its elongation between the emergence of the fifth and sixth roots, suggesting Ceratopteris roots follow a determinate developmental program. We report cell division frequencies in the stem cell niche after detecting labeled nuclei in the root apical cell (RAC) and derivatives after 8 h of exposure. These results demonstrate the RAC has a continuous mitotic activity during root development. Detection of cell cycle activity in the RAC at early times suggests this cell acts as a non-quiescent organizing center. Overall, our results provide a framework to study root function and development in ferns and to better understand the evolutionary history of this organ.

Transcriptional and Morpho-Physiological Responses of Marchantia polymorpha upon Phosphate Starvation.

Phosphate (Pi) is a pivotal nutrient that constraints plant development and productivity in natural ecosystems. Land colonization by plants, more than 470 million years ago, evolved adaptive mechanisms to conquer Pi-scarce environments. However, little is known about the molecular basis underlying such adaptations at early branches of plant phylogeny. To shed light on how early divergent plants respond to Pi limitation, we analyzed the morpho-physiological and transcriptional dynamics of Marchantia polymorpha upon Pi starvation. Our phylogenomic analysis highlights some gene networks present since the Chlorophytes and others established in the Streptophytes (e.g., PHR1-SPX1 and STOP1-ALMT1, respectively). At the morpho-physiological level, the response is characterized by the induction of phosphatase activity, media acidification, accumulation of auronidins, reduction of internal Pi concentration, and developmental modifications of rhizoids. The transcriptional response involves the induction of MpPHR1, Pi transporters, lipid turnover enzymes, and MpMYB14, which is an essential transcription factor for auronidins biosynthesis. MpSTOP2 up-regulation correlates with expression changes in genes related to organic acid biosynthesis and transport, suggesting a preference for citrate exudation. An analysis of MpPHR1 binding sequences (P1BS) shows an enrichment of this cis regulatory element in differentially expressed genes. Our study unravels the strategies, at diverse levels of organization, exerted by M. polymorpha to cope with low Pi availability.

Conservation analysis of core cell cycle regulators and their transcriptional behavior during limb regeneration in Ambystoma mexicanum.

Ambystoma mexicanum (axolotl) has been one of the major experimental models for the study of regeneration during the past 100 years. Axolotl limb regeneration takes place through a multi-stage and complex developmental process called epimorphosis that involves diverse events of cell reprogramming. Such events start with dedifferentiation of somatic cells and the proliferation of quiescent stem cells to generate a population of proliferative cells called blastema. Once the blastema reaches a mature stage, cells undergo progressive differentiation into the diverse cell lineages that will form the new limb. Such pivotal cell reprogramming phenomena depend on the fine-tuned regulation of the cell cycle in each regeneration stage, where cell populations display specific proliferative capacities and differentiation status. The axolotl genome has been fully sequenced and released recently, and diverse RNA-seq approaches have also been generated, enabling the identification and conservatory analysis of core cell cycle regulators in this species. We report here our results from such analyses and present the transcriptional behavior of key regulatory factors during axolotl limb regeneration. We also found conserved protein interactions between axolotl Cyclin Dependent Kinases 2, 4 and 6 and Cyclins type D and E. Canonical CYC-CDK interactions that play major roles in modulating cell cycle progression in eukaryotes.

Deep microbial community profiling along the fermentation process of pulque, a biocultural resource of Mexico.

The biggest non-tree perennial plant species endemic to Mexico were called metl in the Nahua culture; during colonial times, renamed with the Antillean word maguey. Carl von Linné finally renamed them as Agave, a Greek-Latin root word meaning admirable. Since pre-Columbian times, one of the major products obtained from some Agave species is the fermented beverage called pulque or octli. This beverage represents an ancient biotechnological development obtained by the natural fermentation of mead from such plants. Pulque played a central role in Mexican pre-Columbian cultures, while in recent times, there has been a renewed interest in it, due to its high content in nutrients and probiotics. In this study, we used massive sequencing of the 16S rRNA gene and the ribosomal internal transcribed spacer (ITS) to profile the pulque microbiome. We identified 2,855 bacteria operational taxonomic units (OTUs) and 1,494 fungi species in the pulque fermentation. Our results provide the most diverse catalog of microbes during pulque production reported so far. These findings allowed us to identify previously unidentified and core microbes resilient during pulque production, with the potential to be used as fermentation stage biomarkers. We confirmed previous reports of pulque microbes and discovered new ones like the bacteria Sphingomonas and Weisella. Among fungi we found that Saccharomyces cerevisiae was second to Candida zemplina in the studied pulque samples.

Multi-organ transcriptomic landscape of Ambystoma velasci metamorphosis.

Metamorphosis is a postembryonic developmental process that involves morphophysiological and behavioral changes, allowing organisms to adapt into a novel environment. In some amphibians, aquatic organisms undergo metamorphosis to adapt in a terrestrial environment. In this process, these organisms experience major changes in their circulatory, respiratory, digestive, excretory and reproductive systems. We performed a transcriptional global analysis of heart, lung and gills during diverse stages of Ambystoma velasci to investigate its metamorphosis. In our analyses, we identified eight gene clusters for each organ, according to the expression patterns of differentially expressed genes. We found 4064 differentially expressed genes in the heart, 4107 in the lung and 8265 in the gills. Among the differentially expressed genes in the heart, we observed genes involved in the differentiation of cardiomyocytes in the interatrial zone, vasculogenesis and in the maturation of coronary vessels. In the lung, we found genes differentially expressed related to angiogenesis, alveolarization and synthesis of the surfactant protein. In the case of the gills, the most prominent biological processes identified are degradation of extracellular matrix, apoptosis and keratin production. Our study sheds light on the transcriptional responses and the pathways modulation involved in the transformation of the facultative metamorphic salamander A. velasci in an organ-specific manner.