An inducible DNA replication-cell division coupling mechanism in E. coli

Author: Huisman, O.; D’Ari, R. Description: Cell division is a tightly regulated periodic process. In steady-state cultures of Enterobacteriaceae, division takes place at a well defined cell mass and is strictly coordinated with DNA replication. In wild-type Escherichia coli the formation of cells lacking DNA is very rare, and interruptions of DNA replication arrest cell division. The molecular bases of this replication-division coupling have been elusive but several models have been proposed. It has been suggested, for example, that the termination of a round of DNA replication may trigger a…

See more and a link to full text

Morphological plasticity as a bacterial survival strategy

Author: Justice, S.S.; Hunstad, D.A.; Cegelski, L.; Hultgren, S.J. Description: Bacteria have evolved complex systems to maintain consistent cell morphologies. Nevertheless, in certain circumstances, bacteria alter this highly regulated process to transform into filamentous organisms. Accumulating evidence attributes important biological roles to filamentation in stressful environments, including, but not limited to, sites of interaction between pathogenic bacteria and their hosts. Filamentation could represent an intended response to specific environmental cues that promote survival amidst the threats of consumption and killing. Subject headings: Adaptation, Physiological; Animals; Epithelial Cells/microbiology; Escherichia coli/pathogenicity/physiology; Gram-Negative…

See more and a link to full text

Alternatives to Antibiotic Use: Probiotics for the Gut

Author: Reid, Gregor; Friendship, Robert Description: Developed countries are not immune from serious food-borne diseases, and the source is often the intestine of cattle, sheep and poultry livestock. Outbreaks of Escherichia coli 0157, most recently killing people in Ontario, and of salmonella and shigella food poisoning especially during summer months, remind us of the seriousness of the problem. Thus, there is renewed interest in alternative approaches to antibiotics to control bacterial diseases, both in humans and veterinary medicine. Consumers are believed to be concerned not only about bacterial pathogens being…

See more and a link to full text

Memory and fitness optimization of bacteria under fluctuating environments

Author: Lambert, G.; Kussell, E. Description: Bacteria prudently regulate their metabolic phenotypes by sensing the availability of specific nutrients, expressing the required genes for their metabolism, and repressing them after specific metabolites are depleted. It is unclear, however, how genetic networks maintain and transmit phenotypic states between generations under rapidly fluctuating environments. By subjecting bacteria to fluctuating carbon sources (glucose and lactose) using microfluidics, we discover two types of non-genetic memory in Escherichia coli and analyze their benefits. First, phenotypic memory conferred by transmission of stable intracellular lac proteins dramatically…

See more and a link to full text

Inositol 1,4,5-trisphosphate receptors are strongly expressed in the nervous system, pharynx, intestine, gonad and excretory cell of Caenorhabditis elegans and are encoded by a single gene (itr-1)

Author: Baylis, H.A.; Furuichi, T.; Yoshikawa, F.; Mikoshiba, K.; Sattelle, D.B. Description: Inositol 1,4,5-trisphosphate (InsP3) activates receptors (InsP3Rs) that mediate intracellular Ca(2+ )release, thereby modulating intracellular calcium signals and regulating important aspects of cellular physiology and gene expression. To further our understanding of InsP3Rs we have characterised InsP3Rs and the InsP3R gene, itr-1, from the model organism Caenorhabditis elegans. cDNAs encoding InsP3Rs were cloned enabling us to: (a) identify three putative transcription start sites that result in alternative mRNA 5′ ends: (b) detect alternative splicing at three sites and: (c)…

See more and a link to full text

Thermal preference of Caenorhabditis elegans: a null model and empirical tests

Author: Anderson, J.L.; Albergotti, L.; Proulx, S.; Peden, C.; Huey, R.B.; Phillips, P.C. Description: The preferred body temperature of ectotherms is typically inferred from the observed distribution of body temperatures in a laboratory thermal gradient. For very small organisms, however, that observed distribution might misrepresent true thermal preferences. Tiny ectotherms have limited thermal inertia, and so their body temperature and speed of movement will vary with their position along the gradient. In order to separate the direct effects of body temperature on movement from actual preference behavior on a thermal…

See more and a link to full text

A spectrophotometric coupled enzyme assay to measure the activity of succinate dehydrogenase

Author: Jones, A.J.Y.; Hirst, J. Description: Respiratory complex II (succinate:ubiquinone oxidoreductase) connects the tricarboxylic acid cycle to the electron transport chain in mitochondria and many prokaryotes. Complex II mutations have been linked to neurodegenerative diseases and metabolic defects in cancer. However, there is no convenient stoichiometric assay for the catalytic activity of complex II. Here, we present a simple, quantitative, real-time method to detect the production of fumarate from succinate by complex II that is easy to implement and applicable to the isolated enzyme, membrane preparations, and tissue homogenates. Our…

See more and a link to full text

Oxidative stress in bacteria and protein damage by reactive oxygen species

Author: Cabiscol, E.; Tamarit, J.; Ros, J. Description: The advent of O2 in the atmosphere was among the first major pollution events occurred on earth. The reaction between ferrous iron, very abundant in the reductive early atmosphere, and oxygen results in the formation of harmful superoxide and hydroxyl radicals, which affect all macromolecules (DNA, lipids and proteins). Living organisms have to build up mechanisms to protect themselves against oxidative stress, with enzymes such as catalase and superoxide dismutase, small proteins like thioredoxin and glutaredoxin, and molecules such as glutathione. Bacterial…

See more and a link to full text

The Use of Bacteriophages in the Poultry Industry

Author: Żbikowska, K.; Michalczuk, M. & Dolka, B. Description: The emergence of multidrug-resistant infections and antibiotic failures have raised concerns over human and veterinary medicine worldwide. Poultry production has had to confront the problems of an alarming increase in bacterial resistance, including zoonotic pathogens. According to the European Food Safety Authority (EFSA), campylobacteriosis and salmonellosis have been the most frequently reported human foodborne diseases linked to poultry. This situation has strongly stimulated a renewal of scientists’ interest in bacteriophages (phages) since the beginning of the 21st century. Bacteriophages are the…

See more and a link to full text

Antibacterial properties of common herbal remedies of the southwest

Author: Romero, C.D.; Chopin, S.F.; Buck, G.; Martinez, E.; Garcia, M.; Bixby, L. Description: Curanderismo, widely practiced in the southwest, is an alternative medical system that has been neglected by scientific research. This project analyzed the antibiotic properties of 23 common herbal remedies used in South Texas to treat wounds and infections. Ethanolic tinctures and aqueous extracts of each plant were prepared and applied to blank diffusion disks. These disks were desiccated and used in Kirby-Bauer disk diffusion susceptibility tests on three bacteria: Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli….

See more and a link to full text