The respiratory chain of in urine-like conditions: critical roles of NDH-2 and -terminal oxidases.

is an opportunistic nosocomial bacterial pathogen that commonly causes urinary tract infections. Over the past decades, strains have acquired resistance to common antibiotics that has led to the rise of multidrug-resistant and even pandrug-resistant strains. Infections produced by these strains are nearly impossible to treat, which makes a global priority to develop new antibiotics and there is an urgent need to identify targets to treat infections against this pathogen.

Comparison of Two Culture-Based Detection Systems for the Isolation of Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii in Raw Ground Poultry.

Arcobacters are emerging pathogens that have been underestimated due to a lack of a standardized isolation method. The aim of this research was to evaluate the ability to isolate Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii using two Arcobacter-specific culture detection systems: (i) the Houf broth and modified charcoal cefoperazone deoxycholate agar supplemented with cefoperazone, amphotericin B, and teicoplanin (HB/mCCDA+CAT), and (ii) the Nguyen-Restaino-Juárez Arcobacter enrichment broth and chromogenic agar (NRJ-B/M). Both detection systems were evaluated for productivity ratio, sensitivity, and specificity.

NRJ Media as the Gold-Standard -Specific Detection System: Applications in Poultry Testing.

species are ubiquitous emerging pathogens with an impact that has been underestimated due to limitations in isolation and detection methods. Our group recently developed the novel NRJ -detection system, with major improvements in specificity and selectivity compared to other culture-based methods. In this work, the NRJ detection system was evaluated using retail whole broiler chicken carcass.

Identification of the riboflavin cofactor-binding site in the Vibrio cholerae ion-pumping NQR complex: A novel structural motif in redox enzymes.

The ion-pumping NQR complex is an essential respiratory enzyme in the physiology of many pathogenic bacteria. This enzyme transfers electrons from NADH to ubiquinone through several cofactors, including riboflavin (vitamin B2). NQR is the only enzyme reported that is able to use riboflavin as a cofactor.

The Transition Zone Protein AHI1 Regulates Neuronal Ciliary Trafficking of MCHR1 and Its Downstream Signaling Pathway.

The Abelson-helper integration site 1 () gene encodes for a ciliary transition zone localizing protein that when mutated causes the human ciliopathy, Joubert syndrome. We prepared and examined neuronal cultures derived from male and female embryonic and mice (littermates) and found that the distribution of ciliary melanin-concentrating hormone receptor-1 (MchR1) was significantly reduced in neurons; however, the total and surface expression of MchR1 on neurons was similar to controls (). This indicates that a pathway for MchR1 trafficking to the surface plasma membrane is intact, but the process of targeting MchR1 into cilia is impaired in Ahi1-deficient mouse neurons, indicating a role for Ahi1 in localizing MchR1 to the cilium.

Concise Synthesis of 1,4-Benzoquinone-Based Natural Products as Mitochondrial Complex I Substrates and Substrate-Based Inhibitors.

A short, efficient one-step synthesis of 2-methyl-5-(3-methyl-2-butenyl)-1,4-benzoquinone, a natural product from Pyrola media is described. The synthesis is based on a direct late C-H functionalization of the quinone scaffold. The formation of the natural product was confirmed by means of 2D-NMR spectroscopy.

The aerobic respiratory chain of Pseudomonas aeruginosa cultured in artificial urine media: Role of NQR and terminal oxidases.

Pseudomonas aeruginosa is a Gram-negative γ-proteobacterium that forms part of the normal human microbiota and it is also an opportunistic pathogen, responsible for 30% of all nosocomial urinary tract infections. P. aeruginosa carries a highly branched respiratory chain that allows the colonization of many environments, such as the urinary tract, catheters and other medical devices.

Conserved residue His-257 of flavin transferase ApbE plays a critical role in substrate binding and catalysis.

The flavin transferase ApbE plays essential roles in bacterial physiology, covalently incorporating FMN cofactors into numerous respiratory enzymes that use the integrated cofactors as electron carriers. In this work we performed a detailed kinetic and structural characterization of WT ApbE and mutants of the conserved residue His-257, to understand its role in substrate binding and in the catalytic mechanism of this family. Bi-substrate kinetic experiments revealed that ApbE follows a random Bi Bi sequential kinetic mechanism, in which a ternary complex is formed, indicating that both substrates must be bound to the enzyme for the reaction to proceed.

Characterization of the NQR complex, a bacterial proton pump with roles in autopoisoning resistance.

is a Gram-negative bacterium responsible for a large number of nosocomial infections. The respiratory chain contains the ion-pumping NADH:ubiquinone oxidoreductase (NQR). This enzyme couples the transfer of electrons from NADH to ubiquinone to the pumping of sodium ions across the cell membrane, generating a gradient that drives essential cellular processes in many bacteria.

Dynamic energy dependency of on host cell metabolism during intracellular growth: Role of sodium-based energetics in chlamydial ATP generation.

is an obligate intracellular human pathogen responsible for the most prevalent sexually-transmitted infection in the world. For decades has been considered an "energy parasite" that relies entirely on the uptake of ATP from the host cell. The genomic data suggest that respiratory chain could produce a sodium gradient that may sustain the energetic demands required for its rapid multiplication.

Kinetic characterization of Vibrio cholerae ApbE: Substrate specificity and regulatory mechanisms.

ApbE is a member of a novel family of flavin transferases that incorporates flavin mononucleotide (FMN) to subunits of diverse respiratory complexes, which fulfill important homeostatic functions. In this work a detailed characterization of Vibrio cholerae ApbE physiologic activity, substrate specificity and pH dependency was carried out. The data obtained show novel characteristics of the regulation and function of this family.

Identification of the Catalytic Ubiquinone-binding Site of Sodium-dependent NADH Dehydrogenase: A NOVEL UBIQUINONE-BINDING MOTIF.

The sodium-dependent NADH dehydrogenase (Na-NQR) is a key component of the respiratory chain of diverse prokaryotic species, including pathogenic bacteria. Na-NQR uses the energy released by electron transfer between NADH and ubiquinone (UQ) to pump sodium, producing a gradient that sustains many essential homeostatic processes as well as virulence factor secretion and the elimination of drugs. The location of the UQ binding site has been controversial, with two main hypotheses that suggest that this site could be located in the cytosolic subunit A or in the membrane-bound subunit B.

The Kinetic Reaction Mechanism of the Vibrio cholerae Sodium-dependent NADH Dehydrogenase.

The sodium-dependent NADH dehydrogenase (Na(+)-NQR) is the main ion transporter in Vibrio cholerae. Its activity is linked to the operation of the respiratory chain and is essential for the development of the pathogenic phenotype. Previous studies have described different aspects of the enzyme, including the electron transfer pathways, sodium pumping structures, cofactor and subunit composition, among others.

Spatiotemporal differences in the c-fos pathway between C57BL/6J and DBA/2J mice following flurothyl-induced seizures: A dissociation of hippocampal Fos from seizure activity.

Significant differences in seizure characteristics between inbred mouse strains highlight the importance of genetic predisposition to epilepsy. Here, we examined the genetic differences between the seizure-resistant C57BL/6J (B6) mouse strain and the seizure-susceptible DBA/2J (D2) strain in the phospho-Erk and Fos pathways to examine seizure-induced neuronal activity to uncover potential mechanistic correlates to these disparate seizure responsivities. Expression of neural activity markers was examined following 1, 5, or 8 seizures, or after 8 seizures, a 28 day rest period, and a final flurothyl rechallenge.

The Joubert syndrome-associated missense mutation (V443D) in the Abelson-helper integration site 1 (AHI1) protein alters its localization and protein-protein interactions.

Background: Missense mutations in AHI1 result in the neurodevelopmental ciliopathy called Joubert syndrome.

Results: Mutations in AHI1 decrease cilia formation, alter its localization and stability, and change its binding to HAP1 and NPHP1.

Conclusion: Mutations in AHI1 affect ciliogenesis, AHI1 protein localization, and AHI1-protein interactions.

Trafficking in and to the primary cilium.

Polarized vesicle trafficking is mediated by small GTPase proteins, such as Rabs and Arls/Arfs. These proteins have essential roles in maintaining normal cellular function, in part, through regulating intracellular trafficking. Moreover, these families of proteins have recently been implicated in the formation and function of the primary cilium.

[Impaired fasting glucose detection in blood donors population].

Objective: to identify subjects with impaired fasting glucose (IFG), from a group of apparently healthy individuals.

Methods: a cross-sectional study was undertaken in 1188 blood donors, with no family history of diabetes (T2D). All these individuals were subjected to a questionnaire, and biochemical tests.

Volume changes in neurons: hyperexcitability and neuronal death.

Hyponatremia propitiates and increases susceptibility to seizure episodes. In vitro, hyposmolarity induces hyperexcitability and epileptiform activity and increases the amplitude of excitatory postsynaptic potentials. Synaptic (increased glutamate vesicular release) and non-synaptic (swelling-induced extracellular space shrinkage and ephaptic interactions) might be responsible for the hyposmolarity effects on brain excitability.

Mechanisms of cell volume regulation in hypo-osmolality.

Cells respond to a condition of hypo-osmolality by rapid swelling followed by an adaptive response that tends to recover the normal cell volume despite the persistence of the hypo-osmotic condition. This is an active process accomplished by the extrusion of intracellular osmolytes, essentially K+, Cl-, and small organic molecules. This regulatory process operates through a chain of events that essentially consists of a sensor or sensing mechanism to detect changes in cell volume, a signaling cascade to amplify the sensing signal and orient it to activate pathways for osmolyte extrusion, and a memory of the original cell volume, which sets the timing for inactivation of the volume-regulatory process.

Depolarization, exocytosis and amino acid release evoked by hyposmolarity from cortical synaptosomes.

External osmolarity reduction (20%) led to labelled glutamate, GABA and taurine release from rat brain cortical synaptosomes. A Cl--independent, Na+-dependent, La3+-sensitive and tetrodotoxin (TTX) reduced depolarization of synaptosomes occurred upon hyposmolarity, suggestive of Na+ entry through nonselective cation channels. This depolarization, together with cytosolic Ca2+ ([Ca2+]I) increase, resulted in exocytosis, monitored by FM1-43.

Osmolytes and mechanisms involved in regulatory volume decrease under conditions of sudden or gradual osmolarity decrease.

A decrease in external osmolarity results in cell swelling and the immediate activation of a mechanism to restore cell volume, known as regulatory volume decrease (RVD). When exposed to a gradual osmolarity decrease (GODE), some cells do not swell. This reflects the operation of an active regulatory process known as isovolumetric regulation (IVR).