From Endosymbiont to Host-Controlled Organelle: The Hijacking of Mitochondrial Protein Synthesis and Metabolism

Mitochondria are eukaryotic organelles that originated from the endosymbiosis of an alpha-proteobacterium. To gain insight into the evolution of the mitochondrial proteome as it proceeded through the transition from a free-living cell to a specialized organelle, we compared a reconstructed ancestral proteome of the mitochondrion with the proteomes of alpha-proteobacteria as well as with the mitochondrial proteomes in yeast and man. Overall, there has been a large turnover of the mitochondrial proteome during the evolution of mitochondria. Early in the evolution of the mitochondrion, proteins involved in cell envelope synthesis have virtually disappeared, whereas proteins involved in replication, transcription, cell division, transport, regulation, and signal transduction have been replaced by eukaryotic proteins. More than half of what remains from the mitochondrial ancestor in modern mitochondria corresponds to translation, including post-translational modifications, and to metabolic pathways that are directly, or indirectly, involved in energy conversion. Altogether, the results indicate that the eukaryotic host has hijacked the proto-mitochondrion, taking control of its protein synthesis and metabolism

Ancient Landslide Reactivation at the Viaduct No. 1 Located on the Caraca-La-Guaira Highway in Venezuela

Reactivation of an ancient landslide detected in 1987 affected the southern side of the Viaduct No.1 located in the Caracas-La Guaira highway, which connects Caracas, capital of Venezuela, with its main seaport and the Simon Bolivar International Airport. The Viaduct was built in 1953 and covered a gorge of approximately 300 m. It consisted of three parallel double-hinged arch ribs made of plain concrete spanning over approximately 152 m and two smaller access Viaducts on either side of the arch rib span. This paper summarizes the results from geotechnical investigation, the evaluation of inclinometers readings and surface control points and the main rehabilitation measures conducted on the structure

Experiencia de Aprendizaje-Servicio en el Máster de Formación de Profesorado: Un enfoque práctico para futuros educadores

En esta comunicación se describe una experiencia de Aprendizaje-Servicio (ApS) integrada en tres asignaturas del Máster de Formación de Profesorado de Educación Secundaria Obligatoria, Bachillerato y Formación Profesional, en la especialidad de Tecnología, que se imparte en la Universidad Politécnica de Madrid (UPM). El servicio ha consistido en mejorar el “aula-avión” del colegio de educación especial Príncipe de Asturias, para que la experiencia de los alumnos con discapacidad intelectual que la utilizan sea lo más fiel posible a la realidad. Se expone el proceso de investigación-acción que se ha seguido con el fin de conocer el impacto que ha tenido en los estudiantes, fundamentalmente en relación a su futuro profesional. También se analiza el desarrollo de la actividad de ApS para detectar aspectos de mejora. Los resultados reflejan una valoración altamente positiva de cómo la experiencia de ApS ha influido en la formación de los estudiantes como futuros profesores comprometidos con las realidades de sus comunidades educativas

Widespread inter- and intra-domain horizontal gene transfer of d-amino acid metabolism enzymes in eukaryotes

Analysis of the growing number of available fully-sequenced genomes has shown that Horizontal Gene Transfer (HGT) in eukaryotes is more common than previously thought. It has been proposed that genes with certain functions may be more prone to HGT than others, but we still have a very poor understanding of the selective forces driving eukaryotic HGT. Recent work uncovered that D-amino acid racemases have been commonly transferred from bacteria to fungi, but their role in the receiving organisms is currently unknown. Here, we set out to assess whether D-amino acid racemases are commonly transferred to and between eukaryotic groups. For this we performed a global survey that used a novel automated phylogeny-based HGT-detection algorithm (Abaccus). Our results revealed that at least 7.0% of the total eukaryotic racemase repertoire is the result of inter- or intra-domain HGT. These transfers are significantly enriched in plant-associated fungi. For these, we hypothesize a possible role for the acquired racemases allowing to exploit minoritary nitrogen sources in plant biomass, a nitrogen-poor environment. Finally, we performed experiments on a transferred aspartate-glutamate racemase in the fungal human pathogen Candida glabrata, which however revealed no obvious biological role

Origin and evolution of the peroxisomal proteome

BACKGROUND: Peroxisomes are ubiquitous eukaryotic organelles involved in various oxidative reactions. Their enzymatic content varies between species, but the presence of common protein import and organelle biogenesis systems support a single evolutionary origin. The precise scenario for this origin remains however to be established. The ability of peroxisomes to divide and import proteins post-translationally, just like mitochondria and chloroplasts, supports an endosymbiotic origin. However, this view has been challenged by recent discoveries that mutant, peroxisome-less cells restore peroxisomes upon introduction of the wild-type gene, and that peroxisomes are formed from the Endoplasmic Reticulum. The lack of a peroxisomal genome precludes the use of classical analyses, as those performed with mitochondria or chloroplasts, to settle the debate. We therefore conducted large-scale phylogenetic analyses of the yeast and rat peroxisomal proteomes. RESULTS: Our results show that most peroxisomal proteins (39–58%) are of eukaryotic origin, comprising all proteins involved in organelle biogenesis or maintenance. A significant fraction (13–18%), consisting mainly of enzymes, has an alpha-proteobacterial origin and appears to be the result of the recruitment of proteins originally targeted to mitochondria. Consistent with the findings that peroxisomes are formed in the Endoplasmic Reticulum, we find that the most universally conserved Peroxisome biogenesis and maintenance proteins are homologous to proteins from the Endoplasmic Reticulum Assisted Decay pathway. CONCLUSION: Altogether our results indicate that the peroxisome does not have an endosymbiotic origin and that its proteins were recruited from pools existing within the primitive eukaryote. Moreover the reconstruction of primitive peroxisomal proteomes suggests that ontogenetically as well as phylogenetically, peroxisomes stem from the Endoplasmic Reticulum. REVIEWERS: This article was reviewed by Arcady Mushegian, Gáspár Jékely and John Logsdon OPEN PEER REVIEW: Reviewed by Arcady Mushegian, Gáspar Jékely and John Logsdon. For the full reviews, please go to the Reviewers' comments section

Pectin methyl esterases and rhamnogalacturonan hydrolases: weapons for successful Monilinia laxa infection in stone fruit?

The secretion of cell wall‐degrading enzymes is one of the mechanisms used by necrotrophic fungi to colonize host tissues. However, information about virulence factors of Monilinia spp., the causal agents of brown rot in stone fruit, is scarce. Plant cell walls have three main components that are broken down by fungal enzymes: cellulose, hemicellulose and pectin. In order to identify Monilinia laxa candidate proteins involved in pectin hydrolysis, two in vitro approaches were conducted: (i) phenotypic and ecophysiological characterization of growth of the pathogen at different pHs, in glucose‐ and pectin‐containing solid media for 7 days' incubation; and (ii) expression analysis of genes encoding M. laxa pectin methyl esterases (MlPMEs) and rhamnogalacturonan hydrolases (MlRG‐HYDs) after incubation for 0.5, 2, 6, 24 and 48 h in glucose‐ and pectin‐containing liquid media. Phenotypic tests showed the role of carbon source on M. laxa growth rate and aggressiveness, and indicated that pectinases were greatly affected by pH. Gene expression analyses uncovered differences among members of each family of pectinases and between the two families, defining sets of genes expressed at earlier (0.5–6 h) and later (48 h) phases. Notably, the up‐ or down‐regulation of these target genes was carbon source‐dependent. Finally, an in vivo study confirmed the synergistic and complementary role that these genes play in the M. laxa–stone fruit pathosystem. Based on these results, it is hypothesized that MlPME2, MlRG‐HYD1 and MlRG‐HYD2 may be potential virulence factors of M. laxa in the process from infection to colonization.info:eu-repo/semantics/acceptedVersio

Comparative Genomics Used to Predict Virulence Factors and Metabolic Genes among Monilinia Species

Brown rot, caused by Monilinia spp., is among the most important diseases in stonefruits, and some pome fruits (mainly apples). This disease is responsible for significant yield losses,particularly in stone fruits, when weather conditions favorable for disease development appear.To achieve future sustainable strategies to control brown rot on fruit, one potential approach will be to characterize genomic variation among Monilinia spp. to define, among others, the capacity to infect fruit in this genus. In the present work, we performed genomic and phylogenomic comparisons of five Monilinia species and inferred differences in numbers of secreted proteins, including CAZy proteins and other proteins important for virulence. Duplications specific to Monilinia were sparse and, overall, more genes have been lost than gained. Among Monilinia spp., low variability in the CAZome was observed. Interestingly, we identified several secondary metabolism clusters based on similarity to known clusters, and among them was a cluster with homology to pyriculol that could be responsible for the synthesis of chloromonilicin. Furthermore, we compared sequences of all strains available from NCBI of these species to assess their MAT loci and heterokaryon Compatibility systems. Our comparative analyses provide the basis for future studies into understanding how these genomic differences underlie common or differential abilities to interact with the host plant.info:eu-repo/semantics/publishedVersio

Recent trends in molecular diagnostics of yeast infections : from PCR to NGS

The incidence of opportunistic yeast infections in humans has been increasing over recent years. These infections are difficult to treat and diagnose, in part due to the large number and broad diversity of species that can underlie the infection. In addition, resistance to one or several antifungal drugs in infecting strains is increasingly being reported, severely limiting therapeutic options and showcasing the need for rapid detection of the infecting agent and its drug susceptibility profile. Current methods for species and resistance identification lack satisfactory sensitivity and specificity, and often require prior culturing of the infecting agent, which delays diagnosis. Recently developed high-throughput technologies such as next generation sequencing or proteomics are opening completely new avenues for more sensitive, accurate and fast diagnosis of yeast pathogens. These approaches are the focus of intensive research, but translation into the clinics requires overcoming important challenges. In this review, we provide an overview of existing and recently emerged approaches that can be used in the identification of yeast pathogens and their drug resistance profiles. Throughout the text we highlight the advantages and disadvantages of each methodology and discuss the most promising developments in their path from bench to bedside

Controls on intermontane basin filling, isolation and incision on the margin of the Puna Plateau, NW Argentina (similar to 23 degrees S)

Intermontane basins are illuminating stratigraphic archives of uplift, denudation and environmental conditions within the heart of actively growing mountain ranges. Commonly, however, it is difficult to determine from the sedimentary record of an individual basin whether basin formation, aggradation and dissection were controlled primarily by climatic, tectonic or lithological changes and whether these drivers were local or regional in nature. By comparing the onset of deposition, sediment-accumulation rates, incision, deformation, changes in fluvial connectivity and sediment provenance in two interrelated intermontane basins, we can identify diverse controls on basin evolution. Here, we focus on the Casa Grande basin and the adjacent Humahuaca basin along the eastern margin of the Puna Plateau in northwest Argentina. Underpinning this analysis is the robust temporal framework provided by U-Pb geochronology of multiple volcanic ashes and our new magnetostratigraphical record in the Humahuaca basin. Between 3.8 and 0.8 Ma, similar to 120 m of fluvial and lacustrine sediments accumulated in the Casa Grande basin as the rate of uplift of the Sierra Alta, the bounding range to its east, outpaced fluvial incision by the Rio Yacoraite, which presently flows eastward across the range into the Humahuaca basin. Detrital zircon provenance analysis indicates a progressive loss of fluvial connectivity from the Casa Grande basin to the downstream Humahuaca basin between 3 and 2.1 Ma, resulting in the isolation of the Casa Grande basin from 2.1 Ma to \u3c 1.7 Ma. This episode of basin isolation is attributed to aridification due to the uplift of the ranges to the east. Enhanced aridity decreased sediment supply to the Casa Grande basin to the point that aggradation could no longer keep pace with the rate of the surface uplift at the outlet of the basin. Synchronous events in the Casa Grande and Humahuaca basins suggest that both the initial onset of deposition above unconformities at similar to 3.8 Ma and the re-establishment of fluvial connectivity at similar to 0.8 Ma were controlled by climatic and/or tectonic changes affecting both basins. Reintegration of the fluvial network allowed subsequent incision in the Humahuaca basin to propagate upstream into the Casa Grande basin