Regulating inflammation through the anti-inflammatory enzyme platelet-activating factor-acetylhydrolase

Platelet-activating factor (PAF) is one of the most potent lipid mediators involved in inflammatory events. The acetyl group at the sn-2 position of its glycerol backbone is essential for its biological activity. Deacetylation induces the formation of the inactive metabolite lyso-PAF. This deacetylation reaction is catalyzed by PAF-acetylhydrolase (PAF-AH), a calcium independent phospholipase A2 that also degrades a family of PAF-like oxidized phospholipids with short sn-2 residues. Biochemical and enzymological evaluations revealed that at least three types of PAF-AH exist in mammals, namely the intracellular types I and II and a plasma type. Many observations indicate that plasma PAF AH terminates signals by PAF and oxidized PAF-like lipids and thereby regulates inflammatory responses. In this review, we will focus on the potential of PAF-AH as a modulator of diseases of dysregulated inflammation.     

A link between the accumulation of DNA damage and loss of multi‐potency of human mesenchymal stromal cells

Human mesenchymal stromal cells (hMSCs) represent an attractive cell source for clinic applications. Besides being multi‐potent, recent clinical trials suggest that they secrete both trophic and immunomodulatory factors, allowing allogenic MSCs to be used in a wider variety of clinical situations. The yield of prospective isolation is however very low, making expansion a required step toward clinical applications. Unfortunately, this leads to a significant decrease in their stemness. To identify the mechanism behind loss of multi‐potency, hMSCs were expanded until replicative senescence and the concomitant molecular changes were characterized at regular intervals. We observed that, with time of culture, loss of multi‐potency was associated with both the accumulation of DNA damage and the respective activation of the DNA damage response pathway, suggesting a correlation between both phenomena. Indeed, exposing hMSCs to DNA damage agents led to a significant decrease in the differentiation potential. We also showed that hMSCs are susceptible to accumulate DNA damage upon in vitro expansion, and that although hMSCs maintained an effective nucleotide excision repair activity, there was a progressive accumulation of DNA damage. We propose a model in which DNA damage accumulation contributes to the loss of differentiation potential of hMSCs, which might not only compromise their potential for clinical applications but also contribute to the characteristics of tissue ageing.     

Expansion and divergence of the GH locus between spider monkey and chimpanzee

Growth hormone (GH) has been previously described as showing distinct evolutionary stories between primates and other mammals. A burst of changes and successive amplification events took place in the primate lineage giving rise to a multigene family in the three Anthropoidea lineages. Polymerase chain reaction (PCR) was used to obtain the genes and the intergenic regions comprising the GH loci of the spider monkey (Ateles geoffroyi), a New-World primate, and of the chimpanzee (Pan troglodytes), an ape. The intergenic sequences of both species were screened by hybridization to detect copies of the Alu family, which have been implicated in the formation of the human GH locus. The GH locus of the spider monkey contains at least six GH-related genes, four of them were cloned. Likewise, five short intergenic sequences of approximately 3 kb were amplified and cloned. On the other hand, in the chimpanzee four new placental lactogen (PL) genes as well as four intergenic regions were amplified. Consequently, in this ape, six genes (two GHs, previously obtained, and four PLs) are clustered, separated by intergenic sequences of different lengths (two short ones of about 5 kb, and at least two long ones between 9 and 13 kb). The presence of Alu sequences within the intergenic regions of both GH loci corroborates the current hypothesis that they acted as a driving force for the locus expansion. GH sequence comparisons reveal that several gene-conversion events might have occurred during the formation of this genome region, which has undergone independent evolution in the three Anthropoidea branches. To establish the GH's evolutionary history may prove to be a difficult task due to these gene-conversion events.     

Epigenetic repressor-like genes are differentially regulated during grapevine (Vitis vinifera L.) development

Grapevine sexual reproduction involves a seasonal separation between inflorescence primordia (flowering induction) and flower development. We hypothesized that a repression mechanism implicating epigenetic changes could play a role in the seasonal separation of these two developmental processes in grapevine. Therefore, the expression of five grapevine genes with homology to the Arabidopsis epigenetic repressor genes FERTILIZATION INDEPENDENT ENDOSPERM (FIE), EMBRYONIC FLOWER 2 (EMF2), CURLY LEAF (CLF), MULTICOPY SUPPRESSOR OF IRA 1 (MSI1) and SWINGER (SWN) was analyzed during the development of buds and vegetative and reproductive organs. During bud development, the putative grapevine epigenetic repressor genes VvCLF, VvEMF2, VvMSI1, VvSWN and VvFIE are mainly expressed in latent buds at the flowering induction period, but also detected during bud burst and inflorescence/flower development. The overlapping expression patterns of grapevine PcG-like genes in buds suggest that chromatin remodeling mechanisms could be operating during grapevine bud development for controlling processes such as seasonal flowering, dormancy and bud burst. Furthermore, the expression of grapevine PcG-like genes was also detected in fruits and vegetative organs, suggesting that epigenetic changes could be at the basis of the regulation of various proliferation–differentiation cell transitions that occur during grapevine development.     

External validation of Adjuvant! Online breast cancer prognosis tool. Prioritising recommendations for improvement

Background

Adjuvant! Online is a web-based application designed to provide 10 years survival probability of patients with breast cancer. Several predictors have not been assessed in the original Adjuvant! Online study. We provide the validation of Adjuvant! Online algorithm on two breast cancer datasets, and we determined whether the accuracy of Adjuvant! Online is improved with other well-known prognostic factors.

Patients and Methods

The French data set is composed of 456 women with early breast cancer. The Dutch data set is composed of 295 women less than 52 years of age. Agreement between observation and Adjuvant! Online prediction was checked, and logistic models were performed to estimate the prognostic information added by risk factors to Adjuvant! Online prediction.

Results

Adjuvant! Online prediction was overall well-calibrated in the French data set but failed in some subgroups of such high grade and HER2 positive patients. HER2 status, Mitotic Index and Ki67 added significant information to Adjuvant! Online prediction. In the Dutch data set, the overall 10-year survival was overestimated by Adjuvant! Online, particularly in patients less than 40 years old.

Conclusion

Adjuvant! Online needs to be updated to adjust overoptimistic results in young and high grade patients, and should consider new predictors such as Ki67, HER2 and Mitotic Index.     

Transformation of distinct mycobacterial species by shuttle vectors derived from theMycobacterium fortuitum pAL5000 plasmid

Mycobacterium tuberculosis H37Ra,M. smegmatisATCC 607,M. smegmatis MC²155,M. aurum A +,M. aurum A11, and one representative strain ofM. flavescens were transformed by electroporation with plasmid pMY10 and cosmid pDC100. Plasmid pMY 10 contained the origin of replication of pAL5000, the origin of replication of pBR322, a kanamycin resistance gene, and the origin of transfer of the Inc plasmid RK2; the cosmid pDC100 contained the pHC79 SS cosmid, the origin of replication of pAL5000, and a kanamycin resistance gene. The efficiency of transformation varied with the recipient cells used and was in decreasing order: 7×10⁵ forM. smegmatis MC²155, 6×10³ forM. tuberculosis H37Ra, 10³ forM. aurum, 50 forM. smegmatis ATCC 607, and 5 forM. flavescens. A rapid protocol for plasmid extraction from mycobacteria was developed.The satisfactory transformation of the nonvirulentM. tuberculosis strain H37Ra was of interest for future studies on cloning of virulence genes, while the satisfactory transformation ofM. aurum was of interest for future studies on the genetics of drug resistance because these bacteria are sensitive to drugs specifically used in the treatment of tuberculosis and leprosy. However, neither vector was stably maintained inM. smegmatis, indicating that further investigations are still necessary to resolve this difficulty.     

Use of phytoplankton-derived dissolved organic carbon by different types of bacterioplankton

Phytoplankton and heterotrophic prokaryotes are major components of the microbial food web and interact continuously: heterotrophic prokaryotes utilize the dissolved organic carbon derived from phytoplankton exudation or cell lysis (DOCp), and mineralization by heterotrophic prokaryotes provides inorganic nutrients for phytoplankton. For this reason, these communities are expected to be closely linked, although the study of the interactions between them is still a major challenge. Recent studies have presented interactions between phytoplankton and heterotrophic prokaryotes based on coexistence or covariation throughout a time-series. However, a real quantification of the carbon flow within these networks (defined as the interaction strength, IS) has not been achieved yet. This is critical to understand the selectivity degree of bacteria responding to specific algal DOCp. Here we used microautoradiography to quantify the preferences of the major heterotrophic prokaryote phylogenetic groups on DOC derived from several representative phytoplankton species, and expressed these preferences as an IS value. The distribution of the ISs was not random but rather skewed towards weak interactions, in a similar way as the distributions described for stable complex non-microbial ecosystems, indicating that there are some cases of high specificity on the use of specific algal DOCp by some bacterial groups, but weak interactions are more common and may be relevant as well. The variety of IS patterns observed supports the view that the vast range of different resources (different types of organic molecules) available in the sea selects and maintains the high levels of diversity described for marine bacterioplankton.     

Mutations in neuromusculin,a gene encoding a cell adhesion molecule,cause nervous system defects

The Drosophila neuromusculin (nrm) gene encodes an immunoglobulin-like (Ig-like) cell adhesion molecule expressed in the precursors of the embryonic peripheral nervous system (PNS), in the midline precursors of the central nervous system (CNS), and in muscles. During the initial phases of CNS axonogenesis, nrm is expressed in cells involved in the development of commissures and longitudinal tracts. Mutations which alter expression of nrm mRNAs cause aberrant development of commissures and longitudinal axon pathways. Defects in the PNS and muscles of nrm mutants are also observed. In most nrm embryos, abnormal development can be detected in a subset of abdominal segments; however, in approximately 1 of 10 nrm embryos, the defects extend to all segments. Herein, we present evidence that nrm plays an important role in early morphogenesis, possibly by mediating or facilitating inductive cell contacts and movements.     

Following the water? Landscape‐scale temporal changes in bat spatial distribution in relation to Mediterranean summer drought

Understanding how the spatial distribution of ecological resources shapes species’ diversity and abundance in human‐modified landscapes is a central theme in conservation biology. However, studies often disregard that such patterns may vary over time, thereby potentially missing critical environmental constraints to species persistence. This may be particularly important in highly mobile species such as bats, which are able to track temporal variations in spatial resource distribution. Here we test the hypothesis that bats in Mediterranean landscapes are strongly affected by the progressive reduction in water availability during the seasonal summer drought. We analyzed the effects of landscape composition and structure on bat diversity and activity, during pregnancy, lactation, and postlactation periods, and identified the most influential variables within and across periods. Water bodies showed the strongest positive effect on bats, followed by riparian habitats and areas with steeper (>30%) slopes. However, while during pregnancy, there were only small landscape effects, these increased during lactation and postlactation, highlighting a progressively stronger association with water habitats during the summer drought. The spatial projection of habitat models showed that the landscape distribution of bat diversity and activity hotspots changed markedly over time. During pregnancy, the spatial pattern of hotspot distribution was weakly defined, while during lactation and particularly postlactation, there was a concentration of hotspots along permanently flowing watercourses. Our study highlights that permanently flowing watercourses are critical for bat conservation in Mediterranean landscapes, calling for measures to counteract their ongoing degradation due in particular to climate change, water abstraction and damming. More generally, our study underlines the importance of considering the temporal dimension in habitat selection studies, without which there is the risk of overlooking the importance of habitats that are key for species persistence only at certain times of the year.