Search results for "Biochemical Phenomena"
showing 10 items of 496 documents
Phage-borne factors and host LexA regulate the lytic switch in phage GIL01.
2011
ABSTRACT The Bacillus thuringiensis temperate phage GIL01 does not integrate into the host chromosome but exists stably as an independent linear replicon within the cell. Similar to that of the lambdoid prophages, the lytic cycle of GIL01 is induced as part of the cellular SOS response to DNA damage. However, no CI-like maintenance repressor has been detected in the phage genome, suggesting that GIL01 uses a novel mechanism to maintain lysogeny. To gain insights into the GIL01 regulatory circuit, we isolated and characterized a set of 17 clear plaque ( cp ) mutants that are unable to lysogenize. Two phage-encoded proteins, gp1 and gp7, are required for stable lysogen formation. Analysis of …
Horizontal gene transfer of atrazine-degrading genes (atz) from Agrobacterium tumefaciens St96-4 pADP1::Tn5 to bacteria of maize-cultivated soil
2005
International audience; The plasmid pADP1::Tn5 derived from pADP1[Atr(+)] carrying a TnS transposon conferring kanamycin and streptomycin resistances was constructed and introduced in Agrobacterium tumefaciens St96-4. This genetically modified strain was inoculated (similar to 108 cfu g(-1)) in potted soils planted with maize and treated or not with atrazine (1.5 mg kg(-1)). Bulk and maize rhizosphere soils were sampled 39 days after planting to look for soil indigenous bacteria that had acquired pADP1::Tn5. Four transconjugants were isolated from four different soil samples. The estimated transfer frequency of pADP1::Tn5 was 10(-4) per donor. Maize rhizosphere and atrazine treatment had no…
COVID-19, Cation Dysmetabolism, Sialic Acid, CD147, ACE2, Viroporins, Hepcidin and Ferroptosis: A Possible Unifying Hypothesis.
2022
Background: iron and calcium dysmetabolism, with hyperferritinemia, hypoferremia, hypocalcemia and anemia have been documented in the majority of COVID-19 patients at later/worse stages. Furthermore, complementary to ACE2, both sialic acid (SA) molecules and CD147 proved relevant host receptors for SARS-CoV-2 entry, which explains the viral attack to multiple types of cells, including erythrocytes, endothelium and neural tissue. Several authors advocated that cell ferroptosis may be the core and final cell degenerative mechanism. Methods: a literature research was performed in several scientific search engines, such as PubMed Central, Cochrane Library, Chemical Abstract Service. More than 5…
Perceived stress, sources of stress and coping strategies among undergraduate medical students of Nepal: a cross-sectional study
2022
Background: Medical students are subjected to various stressors throughout their training, which has a considerable impact on their physical and mental health. Some students have positive ways of coping, while others take to maladaptive coping measures. This study aims to assess severity, sources of stress, and coping strategies among medical students of a non-Western low-income country from South Asia. Methods: A self-administered questionnaire-based cross-sectional study was carried out. Demographic variables were collected and stress level was assessed using PSS 14 (Perceived Stress Scale 14). The sources of stress were assessed using MSSQ (Medical Student Stressor Questionnaire) and cop…
The role of swarming sites for maintaining gene flow in the brown long-eared bat (Plecotus auritus)
2004
Bat-swarming sites where thousands of individuals meet in late summer were recently proposed as 'hot spots' for gene flow among populations. If, due to female philopatry, nursery colonies are genetically differentiated, and if males and females of different colonies meet at swarming sites, then we would expect lower differentiation of maternally inherited genetic markers among swarming sites and higher genetic diversity within. To test these predictions, we compared genetic variance from three swarming sites to 14 nursery colonies. We analysed biparentally (five nuclear and one sex-linked microsatellite loci) and maternally (mitochondrial D-loop, 550 bp) inherited molecular markers. Three m…
Evidence for a new feminizing Wolbachia strain in the isopod Armadillidium vulgare: evolutionary implications.
2004
Wolbachia are intracellular maternally inherited alpha-Proteobacteria infecting a wide range of arthropods. In the common pill bug Armadillidium vulgare, the known Wolbachia strain is responsible for feminization of genetic males. We have investigated Wolbachia diversity in 20 populations of A. vulgare from west and east Europe, north Africa and north America. A new Wolbachia strain (wVulM) was identified through the variability of the wsp gene, distantly related to that previously known (wVulC) in this host species. No individual with multiple infections was detected. Inoculation experiments indicated that the new wVulM bacterial strain also induces feminization in A. vulgare. However, the…
In silico identification and experimental validation of hits active against KPC-2 β-lactamase
2018
Bacterial resistance has become a worldwide concern, particularly after the emergence of resistant strains overproducing carbapenemases. Among these, the KPC-2 carbapenemase represents a significant clinical challenge, being characterized by a broad substrate spectrum that includes aminothiazoleoxime and cephalosporins such as cefotaxime. Moreover, strains harboring KPC-type β-lactamases are often reported as resistant to available β-lactamase inhibitors (clavulanic acid, tazobactam and sulbactam). Therefore, the identification of novel non β-lactam KPC-2 inhibitors is strongly necessary to maintain treatment options. This study explored novel, non-covalent inhibitors active against KPC-2, …
Coexistence of Wolbachia with Buchnera aphidicola and a Secondary Symbiont in the Aphid Cinara cedri
2004
ABSTRACT Intracellular symbiosis is very common in the insect world. For the aphid Cinara cedri , we have identified by electron microscopy three symbiotic bacteria that can be characterized by their different sizes, morphologies, and electrodensities. PCR amplification and sequencing of the 16S ribosomal DNA (rDNA) genes showed that, in addition to harboring Buchnera aphidicola , the primary endosymbiont of aphids, C. cedri harbors a secondary symbiont (S symbiont) that was previously found to be associated with aphids (PASS, or R type) and an α-proteobacterium that belongs to the Wolbachia genus. Using in situ hybridization with specific bacterial probes designed for symbiont 16S rDNA seq…
A genome-scale study of metabolic complementation in endosymbiotic consortia: the case of the cedar aphid
2017
AbstractBacterial endosymbionts and their insect hosts establish an intimate metabolic relationship. Bacteria offer a variety of essential nutrients to their hosts, whereas insect cells provide the necessary sources of matter and energy to their tiny metabolic allies. These nutritional complementations sustain themselves on a diversity of metabolite exchanges between the cell host and the reduced yet highly specialized bacterial metabolism –which, for instance, overproduces a small set of essential amino acids and vitamins. A well-known case of metabolic complementation is provided by the cedar aphidCinara cedrithat harbors two co-primary endosymbionts,Buchnera aphidicolaBCc andCa.Serratia …
Extreme genome reduction in Buchnera spp.: Toward the minimal genome needed for symbiotic life
2002
Buchnera is a mutualistic intracellular symbiont of aphids. Their association began about 200 million years ago, with host and symbiont lineages evolving in parallel since that time. During this coevolutionary process, Buchnera has experienced a dramatic decrease of genome size, retaining only essential genes for its specialized lifestyle. Previous studies reported that genome size in Buchnera spp. is very uniform, suggesting that genome shrinkage occurred early in evolution, and that modern lineages retain the genome size of a common ancestor. Our physical mapping of Buchnera genomes obtained from five aphid lineages shows that the genome size is not conserved among them, but has been red…