Impact of the Genetic Background on the Composition of the Chicken Plasma MiRNome in Response to a Stress

Circulating extra-cellular microRNAs (miRNAs) have emerged as promising minimally invasive markers in human medicine. We evaluated miRNAs isolated from total plasma as biomarker candidates of a response to an abiotic stress (feed deprivation) in a livestock species. Two chicken lines selected for high (R+) and low (R−) residual feed intake were chosen as an experimental model because of their extreme divergence in feed intake and energy metabolism. Adult R+ and R− cocks were sampled after 16 hours of feed deprivation and again four hours after re-feeding. More than 292 million sequence reads were generated by small RNA-seq of total plasma RNA. A total of 649 mature miRNAs were identified; after quality filtering, 148 miRNAs were retained for further analyses. We identified 23 and 19 differentially abundant miRNAs between feeding conditions and between lines respectively, with only two miRNAs identified in both comparisons. We validated a panel of six differentially abundant miRNAs by RT-qPCR on a larger number of plasma samples and checked their response to feed deprivation in liver. Finally, we evaluated the conservation and tissue distribution of differentially abundant miRNAs in plasma across a variety of red jungle fowl tissues. We show that the chicken plasma miRNome reacts promptly to the alteration of the animal physiological condition driven by a feed deprivation stress. The plasma content of stress-responsive miRNAs is strongly influenced by the genetic background, with differences reflecting the phenotypic divergence acquired through long-term selection, as evidenced by the profiles of conserved miRNAs with a regulatory role in energy metabolism (gga-miR-204, gga-miR-let-7f-5p and gga-miR-122-5p). These results reinforce the emerging view in human medicine that even small genetic differences can have a considerable impact on the resolution of biomarker studies, and provide support for the emerging interest in miRNAs as potential novel and minimally invasive biomarkers for livestock species.     

A natural system of chromosome transfer in Yersinia pseudotuberculosis

The High Pathogenicity Island of Yersinia pseudotuberculosis IP32637 was previously shown to be horizontally transferable as part of a large chromosomal segment. We demonstrate here that at low temperature other chromosomal loci, as well as a non-mobilizable plasmid (pUC4K), are also transferable. This transfer, designated GDT4 (Generalized DNA Transfer at 4°C), required the presence of an IP32637 endogenous plasmid (pGDT4) that carries several mobile genetic elements and a conjugation machinery. We established that cure of this plasmid or inactivation of its sex pilus fully abrogates this process. Analysis of the mobilized pUC4K recovered from transconjugants revealed the insertion of one of the pGDT4-borne ISs, designated ISYps1, at different sites on the transferred plasmid molecules. This IS belongs to the IS6 family, which moves by replicative transposition, and thus could drive the formation of cointegrates between pGDT4 and the host chromosome and could mediate the transfer of chromosomal regions in an Hfr-like manner. In support of this model, we show that a suicide plasmid carrying ISYps1 is able to integrate itself, flanked by ISYps1 copies, at multiple locations into the Escherichia coli chromosome. Furthermore, we demonstrate the formation of RecA-independent cointegrates between the ISYps1-harboring plasmid and an ISYps1-free replicon, leading to the passive transfer of the non-conjugative plasmid. We thus demonstrate here a natural mechanism of horizontal gene exchange, which is less constrained and more powerful than the classical Hfr mechanism, as it only requires the presence of an IS6-type element on a conjugative replicon to drive the horizontal transfer of any large block of plasmid or chromosomal DNA. This natural mechanism of chromosome transfer, which occurs under conditions mimicking those found in the environment, may thus play a significant role in bacterial evolution, pathogenesis, and adaptation to new ecological niches.     

Differences in Acinetobacter baumannii strains and host innate immune response determine morbidity and mortality in experimental pneumonia

Despite many reports documenting its epidemicity, little is known on the interaction of Acinetobacter baumannii with its host. To deepen our insight into this relationship, we studied persistence of and host response to different A. baumannii strains including representatives of the European (EU) clones I-III in a mouse pneumonia model. Neutropenic mice were inoculated intratracheally with five A. baumannii strains and an A. junii strain and at several days morbidity, mortality, bacterial counts, airway inflammation, and chemo- and cytokine production in lungs and blood were determined. A. baumannii RUH875 and RUH134 (EU clone I and II, respectively) and sporadic strain LUH8326 resulted in high morbidity/mortality, whereas A. baumannii LUH5875 (EU clone III, which is less widespread than clone I and II) caused less symptoms. A. baumannii type strain RUH3023(T) and A. junii LUH5851 did not cause disease. All strains, except A. baumannii RUH3023(T) and A. junii LUH5851, survived and multiplied in the lungs for several days. Morbidity and mortality were associated with the severity of lung pathology and a specific immune response characterized by low levels of anti-inflammatory (IL-10) and specific pro-inflammatory (IL-12p40 and IL-23) cytokines at the first day of infection. Altogether, a striking difference in behaviour among the A. baumannii strains was observed with the clone I and II strains being most virulent, whereas the A. baumannii type strain, which is frequently used in virulence studies appeared harmless.     

Desulfosoma profundi sp. nov., a thermophilic sulfate-reducing bacterium isolated from a deep terrestrial geothermal spring in France

A novel strictly anaerobic bacterium designated SPDX02-08^T was isolated from a deep terrestrial geothermal spring located in southwest France. Cells (1–2 × 2–6 μm) were non-motile, non sporulating and stained Gram negative. Strain SPDX02-08^T grew at a temperature between 40 and 60°C (optimum 55°C), pH between 6.3 and 7.3 (optimum 7.2) and a NaCl concentration between 0 and 5 g/l (optimum 2 g/l). Sulfate, thiosulfate and sulfite were used as terminal electron acceptors, but not elemental sulfur, nitrate, nitrite, Fe (III) or fumarate. In the presence of sulfate, strain SPDX02-08^T completely oxidized pyruvate, propionate, butyrate, isobutyrate, valerate, isovalerate and hexadecanoate. Stoichiometric measurements revealed a complete oxidation of part of lactate (0.125 mol of acetate produced per mole lactate oxidized). Strain SPDX02-08^T required yeast extract to oxidize formate and H₂ but did not grow autotrophically on H₂. Among the substrates tested, only pyruvate was fermented. The G+C content of the genomic DNA was 57.6 mol%. Major cellular fatty acids of strain SPDX02-08^T were iso-C_15:0, C_15:0, and C_16:0. Phylogenetic analysis of the 16S small-subunit (SSU) ribosomal RNA gene sequence indicated that strain SPDX02-08^T belongs to the genus Desulfosoma, family Syntrophobacteraceae, having Desulfosoma caldarium as its closest phylogenetic relative (97.6% similarity). The mean DNA/DNA reassociation value between strain SPDX02-08^T and Desulfosoma caldarium was 16.9 ± 2.7%. Based on the polyphasic differences, strain SPDX02-08^T is proposed to be assigned as a new species of the genus Desulfosoma, Desulfosoma profundi sp. nov. (DSM 22937^T = JCM 16410^T). GenBank accession number for the 16S rRNA gene sequence of strain SPDX02-08^T is HM056226.     

Molecular approach to the epidemiology of urinary schistosomiasis in France

BackgroundThe diagnosis of urogenital schistosomiasis is based on the complementarity of serological technique and microscopic examination (ME). Between 2015 and 2019, the number of urinary schistosomiasis tests received in our laboratory increased sharply from 300 to 900 per year.Therefore, we wanted to evaluate the reliability of urine microscopic examination (ME, reference and routine technique) from urine sample by comparing it to other techniques (antigenic technique and PCR). To this end, we optimized two real-time PCRs targeting respectively Schistosoma haematobium (Sh) and Schistosoma mansoni (Sm).Methodology/Principal findings914 urine samples from 846 patients suspected of urogenital schistosomiasis were prescribed and analyzed by PCR and also by antigenic technique for the first 143 samples. The antigenic technique evaluated was Schisto POC-CCA, Rapid Medical Diagnostics. These results (antigenic technique and PCR) were compared to ME which was performed from all urines.The percentage of 14% (128/914) positive cases with the PCR technique and the percentage of 6.0% (54/914) positive cases with ME is significantly different (Chi 2 test, p<0.001). These 128 positive PCRs correspond to 120 different patients, 88.3% (106/120) of them were young migrants and 11.7% (14/120) were French patients returning from travel. Among these migrants, more than 75% (80/106) came from French-speaking West Africa.In addition, the Schisto POC-CCA showed a specificity of 39% (46/117), too poor to be used as a screening tool in low or non-endemic areas.Conclusion/SignificanceTargeted Sh and Sm PCRs in urine are reliable techniques compared to ME (reference technique). In view of our results, we decided to screen urinary schistosomiasis by direct ME always coupled by the PCR technique, which has shown better reliability criteria.     

Tuning magnetic exchange using the versatile azide ligand

The ability of the azido ligand to generate various chemical architectures and magnetic couplings is surveyed, using Cu(II) and Ni(II) derivatives. Depending on the ratio between the azide salt, the metal salt and the tridentate Schiff base LH (L^?:1,1,1-trifluoro-7-(dimethylamino)-4-methyl-5-aza-3-hepten-2-onato), molecular bimetallic [CuL(μ_1,3-N₃)]₂ (1) and monometallic [NiL(μ₁-N₃)] (2) as well as extended {[CuL(μ_1,1-N₃)]}_n (3) and {[Ni₂(μ_1,1-N₃)(μ_1,3-N₃)(L)₂(MeOH)₂]}_n (4) chains were obtained. These systems were fully characterized by X-ray diffraction and magnetic susceptibility measurements. In 1, the asymmetrical double μ_1,3-N₃ bridge mediates a ferromagnetic exchange whereas 3 and 4 exhibit unusual symmetric and asymmetric single μ_1,1-N₃ coordination modes that transmit weak ferromagnetic interactions. Ab initio calculations were systematically performed to clarify the origin of the observed magnetic exchanges and to study the role of the asymmetric coordination modes on the magnetic coupling.     

Nanoparticles as vehicles for delivery of photodynamic therapy agents

Photodynamic therapy (PDT) in cancer treatment involves the uptake of a photosensitizer by cancer tissue followed by photoirradiation. The use of nanoparticles as carriers of photosensitizers is a very promising approach because these nanomaterials can satisfy all the requirements for an ideal PDT agent. This review describes and compares the different individual types of nanoparticles that are currently in use for PDT applications. Recent advances in the use of nanoparticles, including inorganic oxide-, metallic-, ceramic-, and biodegradable polymer-based nanomaterials as carriers of photosensitizing agents, are highlighted. We describe the nanoparticles in terms of stability, photocytotoxic efficiency, biodistribution and therapeutic efficiency. Finally, we summarize exciting new results concerning the improvement of the photophysical properties of nanoparticles by means of biphotonic absorption and upconversion.     

Growth hormone action in the developing neural retina: a proteomic analysis

The possible presence and action of growth hormone (GH) in the neural retina was investigated in newborn mice. The neural retina was found to be a site of GH gene expression, as GH mRNA was abundant in cells of the retinal ganglion cell layer, in which GH was also detected. It was also a site of GH action, since GH receptor (GHR) immunoreactivity mirrored that of GH. Actions of GH within the eye were indicated by a reduction in its axial length and retinal width (its neuroblastic, inner plexiform, and optic fiber layers) in GHR gene disrupted mice (GHR-/-), in comparison with wild type (GHR+/+) littermates. In the absence of GH signaling, four proteins in the retinal proteome of the GHR-/- mice (identified by 2-D gels and MS) differed in abundance with those in the wild type mice. Brain abundant membrane attached signal protein-1 (BASP-1) was down-regulated, whereas protein kinase C inhibitor 1, cyclophilin A, KH domain-containing, RNA-binding, signal transduction-associated protein 3 were up-regulated in GHR-/- mice. These proteins are involved in retinal vascularization, neural proliferation and neurite outgrowth. GH might thus have hitherto unsuspected roles in these processes during retinal development.     

Antifouling activity of sessile bacilli derived from marine surfaces

Marine biofilms are a virtually untapped source of bioactive molecules that may find application as novel antifoulants in the marine paint industry. This study aimed at determining the potential of marine biofilm bacteria to produce novel biomolecules with potential application as natural antifoulants. Nine representative strains were isolated from a range of surfaces and were grown in YEB medium and harvested during the late exponential growth phase. Bacterial biomass and spent culture medium were extracted with ethanol and ethyl acetate, respectively. Extracts were assayed for their antifouling activity using two tests: (1) antimicrobial well diffusion test against a common fouling bacterium, Halomonas marina, and (2) anti-crustacean activity test using Artemia salina. Our results showed that none of the ethanolic extracts (bacterial biomass) were active in either test. In contrast, most of the organic extracts had antimicrobial activity (88%) and were toxic towards A. salina (67%). Sequencing of full 16 S ribosomal DNA analysis showed that the isolates were related to Bacillus mojavensis and Bacillus firmus. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) profiling of ethyl acetate extracts of culture supernatants showed that these species produce the bioactive lipopeptides surfactin A, mycosubtilin and bacillomycin D.