Evidence for a pre-PETM dispersal of the earliest European crocodyloids

Crocodyloid remains from the late Paleocene of Mont de Berru (France) hosted in the collections of the Muséum National d’Histoire Naturelle (Paris, France) and in the Institut royal des Sciences naturelles de Belgique (Brussels, Belgium) are described for the first time. This material, although fragmentary, can be clearly referred on a morphological basis to Asiatosuchus depressifrons (Blainville, 1855), a species previously reported from several Eocene Belgian localities thanks to abundant material including a nearly complete skeleton. The Paleocene material shares with A. depressifrons the number of alveoli involved in the dentary symphysis, the exclusion of the splenials from the symphysis, and the presence of a distinct depression on the jugal. The fossil remains from Berru represent the oldest European crocodyloid. Along with the alligatoroid Diplocynodon remensis Martin, Smith, de Lapparent de Broin, Escuillié and Delfino, 2014, previously reported from the same locality, the crocodyloid A. depressifrons indicates that these genera reached Europe before the Paleocene–Eocene Thermal Maximum. Although more complete remains from outside Europe are needed to refine phylogenetic hypotheses, according to the currently established fossil record the forerunners of diplocynodontids likely dispersed from North America, whereas those related to Asiatosuchus likely dispersed from Asia.     

Synthesis and chiroptical properties of organometallic complexes of helicenic N‐heterocyclic carbenes

Novel [4, 6]helicenes ( 4a,b ) bearing a fused imidazolium unit have been prepared from [4, 6]helicene‐2,3‐di‐n‐propyl‐amines 3a,b . The in situ formation of N‐heterocyclic carbene (NHC) derivatives followed by their complexation to iridium(I) or rhodium(I) gave access to complexes 1a , 1′a , and 1b , containing mono‐coordinated helicene‐NHC, chloro and COD (COD = 1,5‐cyclooctadiene) ligands. Ir and Rh complexes 1a and 1′a were characterized by X‐ray crystallography. HPLC and NMR analyses showed that Ir(I) complex 1b existed as a mixture of two diastereomeric complexes corresponding to enantiomeric pairs M‐(?)/P‐(+)‐ 1b ¹ and M‐(?)/P‐(+)‐ 1b ² which differ by the position of COD through space. The chiroptical properties (electronic circular dichroism and optical rotation) of the four stereoisomers were measured. These complexes were also tested as catalysts in a transfer hydrogenation reaction.     

Chiroptical study of cryptophanes subjected to self‐encapsulation

In 1,1,2,2‐tetrachloroethane‐d₂, the ¹²⁹Xe NMR spectrum of the Xe@cryptophane‐223 complex bearing seven acetate groups (Xe@ 1 complex) shows an unusually broad signal compared with that of its congeners (Chapellet, LL. et al. J. Org. Chem. 2015 ;80:6143–6151). To interpret this unexpected behaviour, a ¹H NMR analysis and a thorough study of the chiroptical properties of 1 as a function of the nature of the solvent have been performed. The ¹H NMR spectra of 1 reveal that a self‐encapsulation phenomenon takes place in DMSO‐d₆ and 1,1,2,2‐tetrachloroethane‐d₂ solvents. Thanks to the separation of the two enantiomers of 1 by HPLC on chiral stationary phase, the two enantiomers of 1 have been studied in detail by polarimetry, electronic (ECD), and vibrational (VCD) circular dichroism spectroscopies. Except for ECD spectroscopy, these chiroptical techniques reveal spectroscopic changes as a function of the nature of the solvent. For instance, in DMSO and 1,1,2,2‐tetrachloroethane, in which the self‐encapsulation phenomenon takes place, the sign of the specific optical rotation of [CD(?)₂₅₄]‐ 1 and [CD(+)₂₅₄]‐ 1 is changed. These results have then been compared with those obtained with cryptophane‐223 bearing only one acetate group on the propylenedioxy linker (compound 2 ) and with cryptophane‐223 bearing six acetate groups (compound 3 ). A self‐encapsulation phenomenon is also observed with compound 2 . Finally, compounds 2 and 3 show different chiroptical properties compared with those obtained with the two enantiomers of compound 1 .     

How shall we use the proteomics toolbox for biomarker discovery?

Biomarker discovery for clinical purposes is one of the major areas in which proteomics is used. However, despite considerable effort, the successes have been relatively scarce. In this perspective paper, we try to highlight and analyze the main causes for this limited success, and to suggest alternate strategies, which will avoid them, without eluding the foreseeable weak points of these strategies. Two major strategies are analyzed, namely, the switch from body fluids to cell and tissues for the initial biomarker discovery step or, if body fluids must be analyzed, the implementation of highly selective protein selection strategies.     

A high-resolution anatomical ontology of the developing murine genitourinary tract

Cataloguing gene expression during development of the genitourinary tract will increase our understanding not only of this process but also of congenital defects and disease affecting this organ system. We have developed a high-resolution ontology with which to describe the subcompartments of the developing murine genitourinary tract. This ontology incorporates what can be defined histologically and begins to encompass other structures and cell types already identified at the molecular level. The ontology is being used to annotate in situ hybridisation data generated as part of the Genitourinary Development Molecular Anatomy Project (GUDMAP), a publicly available data resource on gene and protein expression during genitourinary development. The GUDMAP ontology encompasses Theiler stage (TS) 17-27 of development as well as the sexually mature adult. It has been written as a partonomic, text-based, hierarchical ontology that, for the embryological stages, has been developed as a high-resolution expansion of the existing Edinburgh Mouse Atlas Project (EMAP) ontology. It also includes group terms for well-characterised structural and/or functional units comprising several sub-structures, such as the nephron and juxtaglomerular complex. Each term has been assigned a unique identification number. Synonyms have been used to improve the success of query searching and maintain wherever possible existing EMAP terms relating to this organ system. We describe here the principles and structure of the ontology and provide representative diagrammatic, histological, and whole mount and section RNA in situ hybridisation images to clarify the terms used within the ontology. Visual examples of how terms appear in different specimen types are also provided.     

Local-scale species-energy relationships in fish assemblages of some forested streams of the Bolivian Amazon

Productivity (trophic energy) is one of the most important factors promoting variation in species richness. A variety of species-energy relationships have been reported, including monotonically positive, monotonically negative, or unimodal (i.e. hump-shaped). The exact form of the relationship seems to depend, among other things, on the spatial scale involved. However, the mechanisms behind these patterns are still largely unresolved, although many hypotheses have been suggested. Here we report a case of local-scale positive species-energy relationship. Using 14 local fish assemblages in tropical forested headwater streams (Bolivia), and after controlling for major local abiotic factors usually acting on assemblage richness and structure, we show that rising energy availability through leaf litter decomposition rates allows trophically specialized species to maintain viable populations and thereby to increase assemblage species richness. By deriving predictions from three popular mechanistic explanations, i.e. the 'increased population size', the 'consumer pressure', and the 'specialization' hypotheses, our data provide only equivocal support for the latter.     

First insight into Mycobacterium tuberculosis genetic diversity in Paraguay

Background

Francisella tularensis is a gram negative, facultative intracellular bacterium that is the etiological agent of tularemia. F. novicida is closely related to F. tularensis but has low virulence for humans while being highly virulent in mice. IglA is a 21 kDa protein encoded by a gene that is part of an iglABCD operon located on the Francisella pathogenicity island (FPI).

Results

Bioinformatics analysis of the FPI suggests that IglA and IglB are components of a newly described type VI secretion system. In this study, we showed that IglA regulation is controlled by the global regulators MglA and MglB. During intracellular growth IglA production reaches a maximum at about 10 hours post infection. Biochemical fractionation showed that IglA is a soluble cytoplasmic protein and immunoprecipitation experiments demonstrate that it interacts with the downstream-encoded IglB. When the iglB gene was disrupted IglA could not be detected in cell extracts of F. novicida, although IglC could be detected. We further demonstrated that IglA is needed for intracellular growth of F. novicida. A non-polar iglA deletion mutant was defective for growth in mouse macrophage-like cells, and in cis complementation largely restored the wild type macrophage growth phenotype.

Conclusion

The results of this study demonstrate that IglA and IglB are interacting cytoplasmic proteins that are required for intramacrophage growth. The significance of the interaction may be to secrete effector molecules that affect host cell processes.     

MetaLook: a 3D visualisation software for marine ecological genomics

Background  

Marine ecological genomics can be defined as the application of genomic sciences to understand the structure and function of marine ecosystems. In this field of research, the analysis of genomes and metagenomes of environmental relevance must take into account the corresponding habitat (contextual) data, e.g. water depth, physical and chemical parameters. The creation of specialised software tools and databases is requisite to allow this new kind of integrated analysis.