Duración y éxito de eclosión en diferentes tamaños de nidadas de Crocodylus moreletii (Crocodylia: Crocodilidae)

Background. The Crocodylia begin their life by overcoming the incubation stage with group hatching. Incubation temperature is important for the development of the embryos and the duration of the hatching process, during which they emit sounds. Goals. The effect of the size of the clutch on the duration and success of hatching is reported for the first time, and the hatching process is described. Methods. We used four clutches supplied by the "Granja de Lagartos" farm in Tabasco, Mexico, from the 2010 breeding season, and each was distributed in containers to integrate three clutches of different size: large (15 eggs), medium (nine eggs), and small (one egg). We monitored the temperature, relative humidity, and the number of eggs hatched in each clutch. The duration of hatching and the incubation period were statistically compared, as well as hatching success among the three brood sizes. We made sure that incubation conditions were the same for all boxes. Results. The small clutches (? = 3340, ± 2794 min) and the medium-sized ones (? = 1844 ± 476 min) took less minutes to hatch, and both took less time than the large clutches (? = 9431 ± 768 min). The hatchings began with the vocalization of pre-hatching calls, heard up to a week before eclosion. Conclusions. The size of the clutch influences the duration of hatching, but is not related to hatching success.  Antecedentes. Los Crocodylia inician su historia de vida al superar la etapa de incubación con la eclosión en grupo. La temperatura de incubación es importante para el desarrollo de los embriones y el proceso de eclosión, durante el cual emiten sonidos. Objetivos. Reportar la influencia del tamaño de la nidada sobre la duración y el éxito de eclosión, y describir dicho proceso. Métodos. Se emplearon cuatro nidadas de Crocodylus moreletii de la Unidad de Manejo para la Conservación de la Vida Silvestre (UMA) Granja de Lagartos, en Tabasco, México. Con estas se integraron tres nidadas de diferente tamaño: grande (15 huevos), mediana (9 huevos) y pequeña (un huevo). Se monitorizó la temperatura, la humedad relativa y el número de huevos eclosionados y se compararon estadísticamente la duración de las eclosiones y el periodo de incubación, así como el éxito de la eclosión entre los tres tamaños de nidadas. Por último, se verificó que las condiciones de incubación fueran iguales para todas las nidadas. Resultados. Las nidadas pequeñas (? = 3340 ± 2794) y las medianas (? = 1844 ± 476) tardaron menos minutos en eclosionar en comparación con las nidadas grandes (? = 9431 ± 768). Mientras que el éxito de la eclosión (expresado en porcentaje) y la duración en días del periodo de incubación no mostraron diferencias entre los tres tamaños de nidada. Las eclosiones iniciaron con la emisión de los llamados preeclosionales, los cuales se escucharon una semana antes de la eclosión. Conclusiones. El tamaño de nidada influye en la duración de la eclosión, pero no influye sobre su éxito

An integrated whole genome analysis of Mycobacterium tuberculosis reveals insights into relationship between its genome, transcriptome and methylome.

Human tuberculosis disease (TB), caused by Mycobacterium tuberculosis (Mtb), is a complex disease, with a spectrum of outcomes. Genomic, transcriptomic and methylation studies have revealed differences between Mtb lineages, likely to impact on transmission, virulence and drug resistance. However, so far no studies have integrated sequence-based genomic, transcriptomic and methylation characterisation across a common set of samples, which is critical to understand how DNA sequence and methylation affect RNA expression and, ultimately, Mtb pathogenesis. Here we perform such an integrated analysis across 22 M. tuberculosis clinical isolates, representing ancient (lineage 1) and modern (lineages 2 and 4) strains. The results confirm the presence of lineage-specific differential gene expression, linked to specific SNP-based expression quantitative trait loci: with 10 eQTLs involving SNPs in promoter regions or transcriptional start sites; and 12 involving potential functional impairment of transcriptional regulators. Methylation status was also found to have a role in transcription, with evidence of differential expression in 50 genes across lineage 4 samples. Lack of methylation was associated with three novel variants in mamA, likely to cause loss of function of this enzyme. Overall, our work shows the relationship of DNA sequence and methylation to RNA expression, and differences between ancient and modern lineages. Further studies are needed to verify the functional consequences of the identified mechanisms of gene expression regulation

Developmental Splicing Deregulation in Leukodystrophies Related to EIF2B Mutations

Leukodystrophies (LD) are rare inherited disorders that primarily affect the white matter (WM) of the central nervous system. The large heterogeneity of LD results from the diversity of the genetically determined defects that interfere with glial cells functions. Astrocytes have been identified as the primary target of LD with cystic myelin breakdown including those related to mutations in the ubiquitous translation initiation factor eIF2B. EIF2B is involved in global protein synthesis and its regulation under normal and stress conditions. Little is known about how eIF2B mutations have a major effect on WM. We performed a transcriptomic analysis using fibroblasts of 10 eIF2B-mutated patients with a severe phenotype and 10 age matched patients with other types of LD in comparison to control fibroblasts. ANOVA was used to identify genes that were statistically significantly differentially expressed at basal state and after ER-stress. The pattern of differentially expressed genes between basal state and ER-stress did not differ significantly among each of the three conditions. However, 70 genes were specifically differentially expressed in eIF2B-mutated fibroblasts whatever the stress conditions tested compared to controls, 96% being under-expressed. Most of these genes were involved in mRNA regulation and mitochondrial metabolism. The 13 most representative genes, including genes belonging to the Heterogeneous Nuclear Ribonucleoprotein (HNRNP) family, described as regulators of splicing events and stability of mRNA, were dysregulated during the development of eIF2B-mutated brains. HNRNPH1, F and C mRNA were over-expressed in foetus but under-expressed in children and adult brains. The abnormal regulation of HNRNP expression in the brain of eIF2B-mutated patients was concomitant with splicing dysregulation of the main genes involved in glial maturation such as PLP1 for oligodendrocytes and GFAP in astrocytes. These findings demonstrate a developmental deregulation of splicing events in glial cells that is related to abnormal production of HNRNP, in eIF2B-mutated brains

Gla-rich protein function as an anti-inflammatory agent in monocytes/macrophages: implications for calcification-related chronic inflammatory diseases

Calcification-related chronic inflammatory diseases are multifactorial pathological processes, involving a complex interplay between inflammation and calcification events in a positive feed-back loop driving disease progression. Gla-rich protein (GRP) is a vitamin K dependent protein (VKDP) shown to function as a calcification inhibitor in cardiovascular and articular tissues, and proposed as an anti-inflammatory agent in chondrocytes and synoviocytes, acting as a new crosstalk factor between these two interconnected events in osteoarthritis. However, a possible function of GRP in the immune system has never been studied. Here we focused our investigation in the involvement of GRP in the cell inflammatory response mechanisms, using a combination of freshly isolated human leucocytes and undifferentiated/differentiated THP-1 cell line. Our results demonstrate that VKDPs such as GRP and matrix gla protein (MGP) are synthesized and gamma-carboxylated in the majority of human immune system cells either involved in innate or adaptive immune responses. Stimulation of THP-1 monocytes/macrophages with LPS or hydroxyapatite (HA) up-regulated GRP expression, and treatments with GRP or GRP-coated basic calcium phosphate crystals resulted in the down-regulation of mediators of inflammation and inflammatory cytokines, independently of the protein gamma-carboxylation status. Moreover, overexpression of GRP in THP-1 cells rescued the inflammation induced by LPS and HA, by down-regulation of the proinflammatory cytokines TNF alpha, IL-1 beta and NFkB. Interestingly, GRP was detected at protein and mRNA levels in extracellular vesicles released by macrophages, which may act as vehicles for extracellular trafficking and release. Our data indicate GRP as an endogenous mediator of inflammatory responses acting as an anti-inflammatory agent in monocytes/macrophages. We propose that in a context of chronic inflammation and calcification-related pathologies, GRP might act as a novel molecular mediator linking inflammation and calcification events, with potential therapeutic application.Portuguese Science and Technology Foundation (FCT) [PTDC/SAU-ORG/117266/2010, PTDC/BIM-MEC/1168/2012, UID/Multi/ 04326/2013]; FCT fellowships [SFRH/BPD/70277/2010, SFRH/BD/111824/2015

A comparison of several similarity indices used in the classification of protein sequences: a multivariate analysis.

The present work describes an attempt to identify reliable criteria which could be used as distance indices between protein sequences. Seven different criteria have been tested: i and ii) the scores of the alignments as given by the BESTFIT and the FASTA programs; iii) the ratio parameter, i.e. the BESTFIT score divided by the length of the aligned peptides; iv and v) the statistical significance (Z-scores) of the scores calculated by BESTFIT and FASTA, as obtained by comparison with shuffled sequences; vi) the Z-scores provided by the program RELATE which performs a segment-by-segment comparison of 2 sequences, and vii) an original distance index calculated by the program DOCMA from all the pairwise dotplots between the sequences. These 7 criteria have been tested against the aminoacid sequences of 39 globins and those of the 20 aminoacyl-tRNA synthetases from E. coli. The distances between the sequences were analyzed by the multivariate analysis techniques. The results show that the distances calculated from the scores of the pairwise alignments are not adequately sensitive. The Z-score from RELATE is not selective enough and too demanding in computer time. Three criteria gave a classification consistent with the known similarities between the sequences in the sets, namely the Z-scores from BESTFIT and FASTA and the multiple dotplot comparison distance index from DOCMA

Planar webs of maximum rank and analytic projective surfaces

International audienc

Pipeline Transportation of Heavy Oils, a Strategic, Economic and Technological Challenge

Because of very large reserves mainly located in Venezuela and Canada, heavy crude oils represent a significant energy supply. This article gives an overview of the geographical distribution of their resources and lists the recent projects of production. These projects have to face technological challenges in all phases of operation: reservoir, transportation and refining. The paper focuses on transportation, describing the different methods (heating, dilution, oil-in-water emulsion, upgrading and core annular flow). In order to improve them or develop new ones, a structural and rheological study was undertaken to appraise the origin of the high viscosity and counteract its effect

Mechanical Degradation Onset of Polyethylene Oxide Used as a Hydrosoluble Model Polymer for Enhanced Oil Recovery

Résumé — Seuil de dégradation mécanique de solutions de polymères utilisés en récupération assistée des hydrocarbures — Les polymères hydrosolubles comme les polyacrylamides peuvent être utilisés en récupération assistée des hydrocarbures (Enhanced Oil Recovery (EOR)) par injection de polymère. Cette technique vise à augmenter la production de brut en le poussant du réservoir vers un puits producteur à l’aide d’une solution de polymère suffisamment visqueuse. Les polymères utilisés à cet effet ont des masses moléculaires supérieures à 106 g/mol, ce qui les rend sensibles à la dégradation. En raison des débits élevés utilisés lors de leur injection, mais aussi en raison des taux d’élongation élevés rencontrés dans le réservoir, les polymères peuvent se rompre et perdre leurs propriétés viscosifiantes. Dans la littérature, il a été clairement montré, pour des solutions diluées en régime laminaire, que la dégradation des macromolécules n’était initiée qu’au-delà d’un taux d’élongation critique noté ε · c, et que ce taux d’élongation était une fonction puissance de la masse moléculaire du polymère: ε · c ≈ Mw –k. La présente étude expérimentale de la dégradation mécanique a été menée sur des solutions d’oxydes de polyéthylène pour comprendre la dégradation mécanique non seulement en écoulement laminaire ou turbulent, mais aussi en régime dilué et semi-dilué, ainsi qu’en bon ou mauvais solvant. Il a été mis en évidence que la dégradation mécanique affecte principalement les longue