Oxygen limitation modulates pH regulation of catabolism and hydrogenases, multidrug transporters, and envelope composition inEscherichia coli K-12

Background  

InEscherichia coli, pH regulates genes for amino-acid and sugar catabolism, electron transport, oxidative stress, periplasmic and envelope proteins. Many pH-dependent genes are co-regulated by anaerobiosis, but the overall intersection of pH stress and oxygen limitation has not been investigated.     

HCl-induced and ATP-dependent upregulation of TRPV1 receptor expression and cytokine production by human esophageal epithelial cells

The pathogenesis of gastroesophageal reflux disease (GERD) remains elusive, but recent evidence suggests that early secretion of inflammatory cytokines and chemokines by the mucosa leads to influx of immune cells followed by tissue damage. We previously showed that exposure of esophageal mucosa to HCl causes ATP release, resulting in activation of acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine acetyltransferase (lyso-PAF AT), the enzyme responsible for the production of platelet-activating factor (PAF). In addition, HCl causes release of IL-8 from the esophageal mucosa. We demonstrate that esophageal epithelial cells secrete proinflammatory mediators in response to HCl and that this response is mediated by ATP. Monolayers of the human esophageal epithelial cell line HET-1A were exposed to acidified cell culture medium (pH 5) for 12 min, a total of seven times over 48 h, to simulate the recurrent acid exposure clinically occurring in GERD. HCl upregulated mRNA and protein expression for the acid-sensing transient receptor potential cation channel, subfamily vanilloid member 1 (TRPV1), lyso-PAF AT, IL-8, eotaxin-1, -2, and -3, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1. The chemokine profile secreted by HET-1A cells in response to repeated HCl exposure parallels similar findings in erosive esophagitis patients. In HET-1A cells, the TRPV1 agonist capsaicin reproduced these findings for mRNA of the inflammatory mediators lyso-PAF AT, IL-8, and eotaxin-1. These effects were blocked by the TRPV1 antagonists iodoresiniferatoxin and JNJ-17203212. These effects were imitated by direct application of ATP and blocked by the nonselective ATP antagonist suramin. We conclude that HCl/TRPV-induced ATP release upregulated secretion of various chemoattractants by esophageal epithelial cells. These chemoattractants are selective for leukocyte subsets involved in acute inflammatory responses and allergic inflammation. The data support the validity of HET-1A cells as a model of the response of the human esophageal mucosa in GERD.     

Crustacean Hyperglycemic Hormone (cHH) as a Modulator of Aggression in Crustacean Decapods

Biogenic amines, particularly serotonin, are recognised to play an important role in controlling the aggression of invertebrates, whereas the effect of neurohormones is still underexplored. The crustacean Hyperglycemic Hormone (cHH) is a multifunctional member of the eyestalk neuropeptide family. We expect that this neuropeptide influences aggression either directly, by controlling its expression, or indirectly, by mobilizing the energetic stores needed for the increased activity of an animal. Our study aims at testing such an influence and the possible reversion of hierarchies in the red swamp crayfish, Procambarus clarkii, as a model organism. Three types of pairs of similarly sized males were formed: (1) ‘control pairs’ (CP, n = 8): both individuals were injected with a phosphate saline solution (PBS); (2) ‘reinforced pairs’ (RP, n = 9): the alpha alone was injected with native cHH, and the beta with PBS; (3) ‘inverted pairs’ (IP, n = 9): the opposite of (2). We found that, independently of the crayfish’s prior social experience, cHH injections induced (i) the expression of dominance behaviour, (ii) higher glycemic levels, and (iii) lower time spent motionless. In CP and RP, fight intensity decreased with the establishment of dominance. On the contrary, in IP, betas became increasingly likely to initiate and escalate fights and, consequently, increased their dominance till a temporary reversal of the hierarchy. Our results demonstrate, for the first time, that, similarly to serotonin, cHH enhances individual aggression, up to reverse, although transitorily, the hierarchical rank. New research perspectives are thus opened in our intriguing effort of understanding the role of cHH in the modulation of agonistic behaviour in crustaceans.     

Palmitate activates autophagy in INS-1E β-cells and in isolated rat and human pancreatic islets

We have investigated the in vitro effects of increased levels of glucose and free fatty acids on autophagy activation in pancreatic beta cells. INS-1E cells and isolated rat and human pancreatic islets were incubated for various times (from 2 to 24 h) at different concentrations of glucose and/or palmitic acid. Then, cell survival was evaluated and autophagy activation was explored by using various biochemical and morphological techniques. In INS-1E cells as well as in rat and human islets, 0.5 and 1.0 mM palmitate markedly increased autophagic vacuole formation, whereas high glucose was ineffective alone and caused little additional change when combined with palmitate. Furthermore, LC3-II immunofluorescence co-localized with that of cathepsin D, a lysosomal marker, showing that the autophagic flux was not hampered in PA-treated cells. These effects were maintained up to 18-24 h incubation and were associated with a significant decline of cell survival correlated with both palmitate concentration and incubation time. Ultrastructural analysis showed that autophagy activation, as evidenced by the occurrence of many autophagic vacuoles in the cytoplasm of beta cells, was associated with a diffuse and remarkable swelling of the endoplasmic reticulum. Our results indicate that among the metabolic alterations typically associated with type 2 diabetes, high free fatty acids levels could play a role in the activation of autophagy in beta cells, through a mechanism that might involve the induction of endoplasmic reticulum stress.     

Distribution and evolution of circular miniproteins in flowering plants

Cyclotides are disulfide-rich miniproteins with the unique structural features of a circular backbone and knotted arrangement of three conserved disulfide bonds. Cyclotides have been found only in two plant families: in every analyzed species of the violet family (Violaceae) and in few species of the coffee family (Rubiaceae). In this study, we analyzed >200 Rubiaceae species and confirmed the presence of cyclotides in 22 species. Additionally, we analyzed >140 species in related plant families to Rubiaceae and Violaceae and report the occurrence of cyclotides in the Apocynaceae. We further report new cyclotide sequences that provide insights into the mechanistic basis of cyclotide evolution. On the basis of the phylogeny of cyclotide-bearing plants and the analysis of cyclotide precursor gene sequences, we hypothesize that cyclotide evolution occurred independently in various plant families after the divergence of Asterids and Rosids ( approximately 125 million years ago). This is strongly supported by recent findings on the in planta biosynthesis of cyclotides, which involves the serendipitous recruitment of ubiquitous proteolytic enzymes for cyclization. We further predict that the number of cyclotides within the Rubiaceae may exceed tens of thousands, potentially making cyclotides one of the largest protein families in the plant kingdom.     

Oxidative stress-induced risk factors associated with the metabolic syndrome: a unifying hypothesis

Although the biochemical steps linking insulin resistance with the metabolic syndrome have not been completely clarified, mounting experimental and clinical evidence indicate oxidative stress as an attractive candidate for a central pathogenic role since it potentially explains the appearance of all risk factors and supports the clinical manifestations. In fact, metabolic syndrome patients exhibit activation of biochemical pathways leading to increased delivery of reactive oxygen species, decreased antioxidant protection and increased lipid peroxidation. The described associations between increased abdominal fat storage, liver steatosis and systemic oxidative stress, the diminished concentration of nitric oxide derivatives and antioxidant vitamins and the endothelial oxidative damages observed in subjects with the metabolic syndrome definitively support oxidative stress as the common second-level event in a unifying pathogenic view. Moreover, it has been observed that oxidative stress regulates the expression of genes governing lipid and glucose metabolism through activation or inhibition of intracellular sensors. Diet constituents can modulate redox reactions and the oxidative stress extent, thus also acting on nuclear gene expression. As a consequence of the food-gene interaction, metabolic syndrome patients may express different disease features and extents according to the different pathways activated by oxidative stress-modulated effectors. This view could also explain family differences and interethnic variations in determining risk factor appearance. This review mechanistically focused on oxidative stress events leading to individual disease factor appearance in metabolic syndrome patients and their setting for a more helpful clinical approach.     

New sulfurated derivatives of valproic acid with enhanced histone deacetylase inhibitory activity

One dithiolthione and two new methanethiosulfonate derivatives of valproic acid (VPA) were synthesized and tested in vitro as histone deacetylase (HDAC) inhibitors. The new molecules, as well as their sulfurated moieties, exhibited a much stronger inhibition of HDAC enzymatic and antiproliferative activities and histone hyperacetylation than VPA. ACS 2 is the most interesting compound among the new VPA derivatives and its sulfurated moiety, 5-(4-hydroxyphenyl)-3H-1,2-dithiole-3-thione, also known to be a metabolite of anethole trithione, seems to contribute significantly to its activity. This is the first time that HDAC inhibitory activity is described for dithiolethiones and thiosulfonates.     

Eradications of invasive alien species in Europe: a review

Eradication of alien species is a key conservation tool to mitigate the impacts caused by biologic invasions. The aim of the present paper is to review the eradications successfully completed in Europe and to discuss the main limits to a wider application of this management option in the region. On the basis of the available literature – including conference proceedings, national reports to the Bern Convention, etc. – a total of 37 eradication programmes have been recorded. Thirty-three eradications were carried out on islands and four on the mainland. The rat (Rattus spp.) has been the most common target (n = 25, 67%), followed by the rabbit (n = 4). In many cases, these eradications determined a significant recovery of native biodiversity. Differently to other regions of the world, no eradications of alien invertebrates and marine organisms have been recorded; regarding invasive alien plants, it appears that only some very localized removals have been completed so far in Europe. The limited number of eradications carried out in Europe so far is probably due to the limited awareness of the public and the decision makers, the inadequacy of the legal framework, and the scarcity of resources. Synthetic guidelines for improving the ability of European states to respond to aliens incursions are presented. This revised version was published online in July 2006 with corrections to the Cover Date.     

Carapichea guianensis: the correct name for Psychotria carapichea (Rubiaceae), with a correction on the authority of P. carapichea, and a new combination in Carapichea

The correct name forPsychotria carapichea isCarapichea guianensis. Also, the authority ofPsychotria carapichea was previously incorrectly cited, because of an oversight of the illegitimacy ofTapogomea carapichea Poir. The complex taxonomic history of this species is analyzed, and the authority of the binomial is correctly cited. In addition,P. ligularis, which was treated as closely related toC. guianensis in previous publications, is transferred toCarapichea and it is now known asCarapichea ligularis.     

A new synthetic approach to 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-benzimidazol-2-one(J-113397), the first non-peptide ORL-1 receptor antagonist..

An efficient approach to 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-benzimidazol-2-one (J-113397) 1, the first non-peptide ORL-1 receptor antagonist described in literature, is outlined. After construction of the piperidine framework through Dieckmann cyclization of the Michael adduct 8 of cyclooctylmethylamine to methyl acrylate, condensation with o-phenylendiamine produced the beta-enamino ester 2, which has been conveniently used to construct the benzimidazolone substituent at C-4. Catalytic hydrogenation of intermediate 11 followed by base-promoted cis--trans isomerization of the key compound 12 led to the formation of ester 13, which was converted to the racemic title compound by LiAlH(4) reduction. The pure enantiomers were obtained by chiral preparative HPLC separation using a derivatized cellulose-based stationary phase.