Surface films of Escherichia coli colonies

Abstract Escherichia coli colony surfaces were examined using SEM and TEM. The results indicated that bacterial colonies in the course of their development produce surface films which become thicker with increased growth duration. Membrane vesicles contribute to the formation of the surface film. The complex organization of the film suggests that it may perform specific functions.     

Inhibition of infection‐mediated preterm birth by administration of broad spectrum chemokine inhibitor in mice

Preterm birth (PTB) is the single most important cause of perinatal and infant mortality worldwide. Maternal infection can result in PTB. We investigated the ability of a Broad Spectrum Chemokine Inhibitor (BSCI) to prevent infection‐induced PTB in mice. PTB was initiated in pregnant mice by intraperitoneal injection of lipopolysaccharide (LPS; 50 μg). Half the mice received BSCI (10 mg/kg) 24 hrs prior to and immediately before LPS administration. The impact of LPS alone or LPS plus BSCI was assessed on (i) injection‐to‐delivery interval, foetal survival rate, placental and neonates' weight; (ii) amniotic fluid and maternal plasma cytokine levels (by Luminex assay); foetal and maternal tissue cytokine gene expression levels (by Real‐Time RT‐PCR); (iii) immune cells infiltration into the uterine tissue (by stereological immunohistochemistry). Pre‐treatment with BSCI (i) decreased LPS‐induced PTB (64% versus 100%, P < 0.05); (ii) significantly attenuated cytokine/chemokine expression in maternal tissues (plasma, liver, myometrium, decidua); (iii) significantly decreased neutrophil infiltration in the mouse myometrium. BSCI‐treated mice in which PTB was delayed till term had live foetuses with normal placental and foetal weight. BSCI represents a promising new class of therapeutics for PTB. In a mouse model of preterm labour, BCSI suppresses systemic inflammation in maternal tissues which resulted in the reduced incidence of LPS‐mediated PTB. These data provide support for efforts to target inflammatory responses as a means of preventing PTB.     

Extracellular vesicle RNAs reflect placenta dysfunction and are a biomarker source for preterm labour

Preterm birth (PTB) can lead to lifelong complications and challenges. Identifying and monitoring molecular signals in easily accessible biological samples that can diagnose or predict the risk of preterm labour (PTL) in pregnant women will reduce or prevent PTBs. A number of studies identified putative biomarkers for PTL including protein, miRNA and hormones from various body fluids. However, biomarkers identified from these studies usually lack consistency and reproducibility. Extracellular vesicles (EVs) in circulation have gained significant interest in recent years as these vesicles may be involved in cell‐cell communication. We have used an improved small RNA library construction protocol and a newly developed size exclusion chromatography (SEC)‐based EV purification method to gain a comprehensive view of circulating RNA in plasma and its distribution by analysing RNAs in whole plasma and EV‐associated and EV‐depleted plasma. We identified a number of miRNAs in EVs that can be used as biomarkers for PTL, and these miRNAs may reflect the pathological changes of the placenta during the development of PTL. To our knowledge, this is the first study to report a comprehensive picture of circulating RNA, including RNA in whole plasma, EV and EV‐depleted plasma, in PTL and reveal the usefulness of EV‐associated RNAs in disease diagnosis.     

Benchmark of different charges for prediction of the partitioning coefficient through the hydrophilic/lipophilic index

A few different theoretical methods for assigning the partial atomic charges were benchmarked for calculation of the hydrophilic/lipophilic index (HLI). The coefficients were selected to produce the best correlation of the HLI values with the experimental octanol-water partition. Different parameters were checked in calculations of partial charges to get the best performance of the HLI values obtained. Thus, four partitioning schemes (Coulson, Mulliken, Merz-Kollman, Ford-Wang) were benchmarked for calculations of atomic charges with six semiempirical methods (AM1, PM3, RM1, PM6, PM6-D3H4, PM7). Moreover, five distinct types of partial atomic charges (Mulliken, Hirshfeld, Löwdin, CHELPG, NPA), obtained at the Hartree–Fock and DFT levels of theory with three basis sets, were tested for their ability to produce the HLI values with the best correlation to experimental logP coefficients of 50 mono-charged organic anions. In the case of the semiempirical methods, the best correlation between the HLI and logP values (the correlation coefficient r?=?0.9216) was obtained with the AM1 Ford–Wang parametric electrostatic potential charges. The Mulliken and Coulson charges calculated with the PM7 method can be used as an alternative to AM1, with the r values of 0.9107 and 0.8984, respectively. In the case of the DFT, the PBE/def2-TZVP natural population analysis charges produce the best correlation (r?=?0.9220). Nevertheless, in spite of a marginally lower performance (r?=?0.9159), the NPA charges computed at the PBE/def2-SVP level are more robust and can be regarded as the optimum choice for calculating the HLI values.

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Graphical abstract The hydrophilic/lipophilic index (HLI)

     

New belemnites (Megateuthididae,Cylindroteuthididae) from the Bajocian and Bathonian of the Yuryung-Tumus Peninsula,northern Siberia,Russia and their palaeobiogeographic implications

New species of Paramegateuthis (Megateuthididae) and Cylindroteuthis (Cylindroteuthididae) are described from the Bajocian–Bathonian boundary interval of the Yuryung-Tumus Peninsula, northern Siberia, Russia. Additionally, Paramegateuthis subishmensis Stoyanova-Vergilova, 1983, first documented from the Sub-Mediterranean region, is described herein from the Arctic. We propose the presence of a temporary passage between the Boreal and Tethyan seas in the European part of Russia during the Early Bajocian Humphriesianum Chronozone as an explanation of the migration of P. subishmensis. New belemnite records from the Yuryung-Tumus section contribute to the palaeontological characteristics of the Arctic domain.     

ERAD‐dependent control of the Wnt secretory factor Evi

Active regulation of protein abundance is an essential strategy to modulate cellular signaling pathways. Within the Wnt signaling cascade, regulated degradation of β‐catenin by the ubiquitin‐proteasome system (UPS) affects the outcome of canonical Wnt signaling. Here, we found that abundance of the Wnt cargo receptor Evi (Wls/GPR177), which is required for Wnt protein secretion, is also regulated by the UPS through endoplasmic reticulum (ER)‐associated degradation (ERAD). In the absence of Wnt ligands, Evi is ubiquitinated and targeted for ERAD in a VCP‐dependent manner. Ubiquitination of Evi involves the E2‐conjugating enzyme UBE2J2 and the E3‐ligase CGRRF1. Furthermore, we show that a triaging complex of Porcn and VCP determines whether Evi enters the secretory or the ERAD pathway. In this way, ERAD‐dependent control of Evi availability impacts the scale of Wnt protein secretion by adjusting the amount of Evi to meet the requirement of Wnt protein export. As Wnt and Evi protein levels are often dysregulated in cancer, targeting regulatory ERAD components might be a useful approach for therapeutic interventions.     

Positive selection on sociobiological traits in invasive fire ants

The fire ant Solenopsis invicta and its close relatives are highly invasive. Enhanced social cooperation may facilitate invasiveness in these and other invasive ant species. We investigated whether invasiveness in Solenopsis fire ants was accompanied by positive selection on sociobiological traits by applying a phylogenomics approach to infer ancient selection, and a population genomics approach to infer recent and ongoing selection in both native and introduced S. invicta populations. A combination of whole‐genome sequencing of 40 haploid males and reduced‐representation genomic sequencing of 112 diploid workers identified 1,758,116 and 169,682 polymorphic markers, respectively. The resulting high‐resolution maps of genomic polymorphism provide high inference power to test for positive selection. Our analyses provide evidence of positive selection on putative ion channel genes, which are implicated in neurological functions, and on vitellogenin, which is a key regulator of development and caste determination. Furthermore, molecular functions implicated in pheromonal signalling have experienced recent positive selection. Genes with signatures of positive selection were significantly more often those overexpressed in workers compared with queens and males, suggesting that worker traits are under stronger selection than queen and male traits. These results provide insights into selection pressures and ongoing adaptation in an invasive social insect and support the hypothesis that sociobiological traits are under more positive selection than nonsocial traits in such invasive species.     

Effects of 5-azacytidine on the development of parthenogenetic mouse embryos

This study describes the effects of 5-azacytidine (5-azaC) on the development of diploid parthenogenetic embryos (PE) of CBA, C57BL/6 and (CBA × C57BL/6)F₁ mice in vitro at the 1-cell or the blastocyst stage or in vivo after implantation. Our findings indicate that genomic imprinting is modulated by genetic background. Non-fertilized C57BL/6 eggs form diploid parthenogenetic blastocysts at a much higher frequency than CBA eggs. Eggs from F₁ hybrid females form parthenogenetic blastocysts at an approximately intermediate level between these inbred strains of mice. C57BL/6 PE do not develop to the somite stages. In contrast, CBA PE and F₁ PE develop to various somite stages. Following administration of 5–azaC at 1.0 μmol/L in vitro at the 1- -cell stage, the number of implantations of C57BL/6 PE transferred to pseudopregnant females increased. In contrast, the number of implantations and somite F₁ PE did not significantly change following exposure to 5–azaC. However, administration of 5-azaC at the 1-cell stage stimulates development of somite F₁ PE. Administration of 5-azaC at 0.2 and 1.0 μmol/L in vitro at the blastocyst stage did not change the number of implantations of C57BL/6 PE. However, the number of implantations and somite CBA PE decreased. After injection of 5azaC at 0.24mg/kg in vivo at day 8 of gestation, some F₁ PE developed to 26–35 somites compared with a maximum of 25 somites in controls. The different effects of 5-azaC on the development of PE depend upon the mouse strain used and the stage of development.