A pan-genome of 69 Arabidopsis thaliana accessions reveals a conserved genome structure throughout the global species range.

Although originally primarily a system for functional biology, Arabidopsis thaliana has, owing to its broad geographical distribution and adaptation to diverse environments, developed into a powerful model in population genomics. Here we present chromosome-level genome assemblies of 69 accessions from a global species range. We found that genomic colinearity is very conserved, even among geographically and genetically distant accessions. Along chromosome arms, megabase-scale rearrangements are rare and typically present only in a single accession. This indicates that the karyotype is quasi-fixed and that rearrangements in chromosome arms are counter-selected. Centromeric regions display higher structural dynamics, and divergences in core centromeres account for most of the genome size variations. Pan-genome analyses uncovered 32,986 distinct gene families, 60% being present in all accessions and 40% appearing to be dispensable, including 18% private to a single accession, indicating unexplored genic diversity. These 69 new Arabidopsis thaliana genome assemblies will empower future genetic research.

A Reference Genome Assembly for the Spotted Flycatcher (Muscicapa striata).

The spotted flycatcher (Muscicapa striata) forms with the Mediterranean flycatcher (Muscicapa tyrrhenica) a newly recognized species pair of trans-Saharan migratory passerines. These flycatchers present a nested peripatric distribution, a pattern especially unusual among high dispersal species that questions the eco-evolutionary factors involved during the speciation process. Here, we present a genome assembly for M. striata assembled using a combination of Nanopore and Illumina sequences. The final assembly is 1.08 Gb long and consists of 4,779 contigs with an N50 of 3.2 Mb. The completeness of our M. striata genome assembly is supported by the number of BUSCO (95%) and ultraconserved element (UCE) (4889/5041; 97.0%) loci retrieved. This assembly showed high synteny with the Ficedula albicollis reference genome, the closest species for which a chromosome-scale reference genome is available. Several inversions were identified and will need to be investigated at the family level.

Methanobacterium alkalithermotolerans sp. nov., a novel alkaliphilic and hydrogen-utilizing methanogen isolated from an alkaline geothermal spring (La Crouen, New Caledonia).

An anaerobic, hydrogenotrophic methane-producing archaeon was isolated from an alkaline thermal spring (42 °C, pH 9.0) in New Caledonia. This methanogen, designated strain CANT, is alkaliphilic, thermotolerant, with Gram-positive staining non-motile cells. Strain CANT grows autotrophically using hydrogen exclusively as an energy source and carbon dioxide as the sole carbon source (without the requirement of yeast extract or other organic compounds). It grows at 20-45 °C (optimum, 45 °C) and pH 7.3-9.7 (optimum, pH 9.0). NaCl is not required for growth (optimum 0 %) but is tolerated up to 1.5 %. It resists novobiocin, streptomycin and vancomycin but is inhibited by ampicillin and penicillin, among other antibiotics. The genome consists of a circular chromosome (2.2 Mb) containing 2126 predicted protein-encoding genes with a G+C content of 36.4 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain CANT is a member of the genus Methanobacterium, most closely related to the alkaliphilic Methanobacterium alcaliphilum WeN4T with 98.5 % 16S rRNA gene sequence identity. The genomes of strain CANT and M. alcaliphilum DSM 3459, sequenced in this study, share 71.6 % average nucleotide identity and 14.0 % digital DNA-DNA hybridization. Therefore, phylogenetic and physiological results indicate that strain CANT represents a novel species, for which the name Methanobacterium alkalithermotolerans sp. nov. is proposed, and strain CANT (=DSM 102889T= JCM 31304T) is assigned as the type strain.

A supernumerary "B-sex" chromosome drives male sex determination in the Pachón cavefish, Astyanax mexicanus.

Sex chromosomes are generally derived from a pair of classical type-A chromosomes, and relatively few alternative models have been proposed up to now.1,2 B chromosomes (Bs) are supernumerary and dispensable chromosomes with non-Mendelian inheritance found in many plant and animal species3,4 that have often been considered as selfish genetic elements that behave as genome parasites.5,6 The observation that in some species Bs can be either restricted or predominant in one sex7-14 raised the interesting hypothesis that Bs could play a role in sex determination.15 The characterization of putative B master sex-determining (MSD) genes, however, has not yet been provided to support this hypothesis. Here, in Astyanax mexicanus cavefish originating from Pachón cave, we show that Bs are strongly male predominant. Based on a high-quality genome assembly of a B-carrying male, we characterized the Pachón cavefish B sequence and found that it contains two duplicated loci of the putative MSD gene growth differentiation factor 6b (gdf6b). Supporting its role as an MSD gene, we found that the Pachón cavefish gdf6b gene is expressed specifically in differentiating male gonads, and that its knockout induces male-to-female sex reversal in B-carrying males. This demonstrates that gdf6b is necessary for triggering male sex determination in Pachón cavefish. Altogether these results bring multiple and independent lines of evidence supporting the conclusion that the Pachón cavefish B is a "B-sex" chromosome that contains duplicated copies of the gdf6b gene, which can promote male sex determination in this species.

Genome sequence of the coffee root-knot nematode Meloidogyne exigua.

Root-knot nematodes (Meloidogyne spp.) cause serious damages on most crops. Here, we report a high-quality genome sequence of Meloidogyne exigua (population Mex1, Costa Rica), a major pathogen of coffee. Its mitogenome (20,974 bp) was first assembled and annotated. The nuclear genome was then constructed consisting of 206 contigs, with an N50 length of 1.89 Mb and a total assembly length of 42.1 Mb.

Alkalicella caledoniensis gen. nov., sp. nov., a novel alkaliphilic anaerobic bacterium isolated from 'La Crouen' alkaline thermal spring, New Caledonia.

A novel anaerobic, alkaliphilic, mesophilic, Gram-stain-positive, endospore-forming bacterium was isolated from an alkaline thermal spring (42 °C, pH 9.0) in New Caledonia. This bacterium, designated strain LB2T, grew at 25-50 °C (optimum, 37 °C) and pH 8.2-10.8 (optimum, pH 9.5). Added NaCl was not required for growth (optimum, 0-1 %) but was tolerated up to 7 %. Strain LB2T utilized a limited range of substrates, such as peptone, pyruvate, yeast extract and xylose. End products detected from pyruvate fermentation were acetate and formate. Both ferric citrate and thiosulfate were used as electron acceptors. Elemental sulphur, nitrate, nitrite, fumarate, sulphate, sulfite and DMSO were not used as terminal electron acceptors. The two major cellular fatty acids were iso-C15 : 0 and C16 : 0. The genome consists of a circular chromosome (3.7 Mb) containing 3626 predicted protein-encoding genes with a G+C content of 36.2 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the isolate is a member of the family Proteinivoraceae, order Clostridiales within the phylum Firmicutes. Strain LB2T was most closely related to the thermophilic Anaerobranca gottschalkii LBS3T (93.2 % 16S rRNA gene sequence identity). Genome-based analysis of average nucleotide identity and digital DNA-DNA hybridization of strain LB2T with A. gottschalkii LBS3T showed respective values of 70.8 and 13.4 %. Based on phylogenetic, genomic, chemotaxonomic and physiological properties, strain LB2T is proposed to represent the first species of a novel genus, for which the name Alkalicella caledoniensis gen. nov., sp. nov. is proposed (type strain LB2T=DSM 100588T=JCM 30958T).

Characterisation of hydrocarbon degradation, biosurfactant production, and biofilm formation in Serratia sp. Tan611: a new strain isolated from industrially contaminated environment in Algeria.

A novel bacterial strain was isolated from industrially contaminated waste water. In the presence of crude oil, this strain was shown to reduce the rate of total petroleum hydrocarbons (TPH) up to 97.10% in 24 h. This bacterium was subsequently identified by 16S rRNA gene sequence analysis and affiliated to the Serratia genus by the RDP classifier. Its genome was sequenced and annotated, and genes coding for catechol 1,2 dioxygenase and naphthalene 1,2-dioxygenase system involved in aromatic hydrocarbon catabolism, and LadA-type monooxygenases involved in alkane degradation, were identified. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of crude oil after biological treatment showed that Serratia sp. Tan611 strain was able to degrade n-alkanes (from C13 to C25). This bacterium was also shown to produce a biosurfactant, the emulsification index (E24) reaching 43.47% and 65.22%, against vegetable and crude oil, respectively. Finally, the formation of a biofilm was increased in the presence of crude oil. These observations make Serratia sp. Tan611 a good candidate for hydrocarbon bioremediation.

Gut Microbiota-Derived Metabolite Signature in Suckling and Weaned Piglets.

The gut microbiota plays a key role in intestinal development at the suckling-to-weaning transition. The objective of this study was to analyze the production of metabolites by the gut microbiota in suckling and weaned piglets. We studied piglets raised in two separate maternity farms and weaned at postnatal day 21 in the same farm. The fecal metabolome (1H nuclear magnetic resonance) and the microbiota composition (16S rRNA gene amplicon sequencing) and its predicted functions (PICRUSt2) were analyzed in the same piglets during the suckling period (postnatal day 13) and 2 days after weaning (postnatal day 23). The relative concentrations of the bacterial metabolites methylamine, dimethylamine, cadaverine, tyramine, putrescine, 5-aminovalerate, succinate, and 3-(4-hydroxyphenylpropionate) were higher during the suckling period than after weaning. In contrast, the relative concentrations of the short-chain fatty acids acetate and propionate were higher after weaning than during the suckling period. The maternity of origin of piglets also influenced the level of some bacterial metabolites (propionate and isobutyrate). The fecal metabolome signatures observed in suckling and weaned piglets were associated with specific microbiota-predicted functionalities, structure, and diversity. Gut microbiota-derived metabolites, which are differentially abundant between suckling and weaned piglets (e.g., short-chain fatty acids and biogenic amines), are known to regulate gut health. Thus, identification of metabolome signatures in suckling and weaned piglets paves the way for the development of health-promoting nutritional strategies, targeting the production of bacterial metabolites in early life.

Complete Genome Sequence of Microbacterium sp. Strain Nx66, Isolated from Waters Contaminated with Petrochemicals in El Saf-Saf Valley, Algeria.

Microbacterium sp. strain Nx66 was isolated from waters contaminated by petrochemical effluents collected in Algeria. Its genome was sequenced using Illumina MiSeq (2 × 150-bp read pairs) and Oxford Nanopore (long reads) technologies and was assembled using Unicycler. It is composed of one chromosome of 3.42 Mb and one plasmid of 34.22 kb.

Related factors for ProSeal™ laryngeal mask airway failure / Factores relacionados con insuficiencia de las vías respiratorias con el uso de ProSeal™ laryngeal mask

Abstract Introduction: The laryngeal mask airway (LMA) is a device for airway management that is easy to insert, safe, and efficient. However, there are associated complications that can lead to important patient morbidity and mortality, as ventilator failure, can occur with reported incidence between 0.2% and 4.7%. Male gender, advanced age, obesity, short thyromental distance, and poor dentition are known related factors to LMA failure. Objective: Determine the incidence of ProSeal™ LMA ventilatory failure and identify clinical related conditions. Materials and methods: Observational analytic study a group of adult patients with ProSealTM laryngeal mask for airway management. Statistical analysis was performed using STATA 12.1 software. Bivariate analysis was done using Fisher's exact test or Chi2 as it corresponded with statistical significance defined as P value <0.05. Skewed logistic regression for multivariate analysis was performed for estimating adjusted odd ratios (ORs). Results: Incidence of ProSealTM LMA ventilatory failure was 5.2%. In the group of patients that presented failure, 69 were older than 75 years (OR=1.06, 95% confidence interval [CI] 1.03-1.09, P < 0.001), 6 (23.1%) thyromental distance less than 6 x0200A;cm (OR = 2.48, 95% CI 0.93-6.62, P = 0.069), 5 (19.2%), inadequate anesthetic depth and/or laryngospasm (OR=5.78, 95% CI 2.23-14.96, P< 0.001) and 9 (34.6%) vintraoperative use of neuromuscular blockers (NMB) (OR=2.35, 95% CI 1.06-5.21, P=0.035). Conclusion: In patients with LMA management, the age, intraoperative use of NMB and inadequate anesthetic depth and/ or laryngospasm are clinical related conditions for ProSealTMLMA ventilatory failure.

Resumen Introducción: La mascarilla laríngea de vía aérea (LMA) es un dispositivo para el manejo de la vía aérea fácil de insertar, seguro y eficiente. Sin embargo, hay complicaciones asociadas que pueden llevar a morbilidad y mortalidad del paciente, como la falla del respirador, con una incidencia reportada de entre el 0.2% y el 4.7%. El sexo masculino, la edad avanzada, la obesidad, la corta distancia tiromentoniana y la mala dentición son factores conocidos relacionados con el fracaso de la LMA. Objetivo: Determinar la incidencia de la insuficiencia respiratoria con ProSeal™ LMA e identificar las condiciones clínicas relacionadas. Materiales y métodos: Estudio analítico observacional de un grupo de pacientes adultos con uso de ProSeal™ Laryngeal Mask para el manejo de las vías respiratorias. El análisis estadístico se realizó utilizando el software STATA 12.1©. El análisis bivariado se realizó utilizando la prueba exacta de Fisher o Chi2, ya que correspondía a la significación estadística definida como valor de p < 0.05. Se realizó una regresión logística sesgada para el análisis multivariado, con el fin de estimar las proporciones impares ajustadas (OR). Resultados: La incidencia de fallo ventilatorio de ProSeal™ LMA fue del 5.2%. En el grupo de pacientes que presentaron fracaso, 69 eran mayores de 75 años (OR = 1.06; IC del 95%: 1.03 a 1.09; p < 0.001), 6 pacientes (23.1%) tenían distancia tiromentoniana inferior a 6 cm (OR = 2.48; IC del 95%: 0.93 a 6.62, p = 0.069), 5 (19.2%) presentaron profundidad inadecuada del anestésico y/o laringoespasmo (OR = 5.78; IC del 95%: 2.23 a 14.96; p < 0.001) y en 9 (34.6%) hubo uso intraoperatorio de NMB (OR = 2.35; IC del 95%: 1.06 a 5.21; p = 0.035). Conclusión: En pacientes con manejo de la LMA, la edad, el uso intraoperatorio de la NMB y la profundidad anestésica inadecuada y/o laringoespasmo son condiciones clínicas relacionadas con la insuficiencia respiratoria de la LMA ProSeal™.