Clade 8 and Clade 6 Strains of Escherichia coli O157:H7 from Cattle in Argentina have Hypervirulent-Like Phenotypes

The hemolytic uremic syndrome (HUS) whose main causative agent is enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a disease that mainly affects children under 5 years of age. Argentina is the country with the highest incidence of HUS in the world. Cattle are a major reservoir and source of infection with E. coli O157:H7. To date, the epidemiological factors that contribute to its prevalence are poorly understood. Single nucleotide polymorphism (SNP) typing has helped to define nine E. coli O157:H7 clades and the clade 8 strains were associated with most of the cases of severe disease. In this study, eight randomly selected isolates of EHEC O157:H7 from cattle in Argentina were studied as well as two human isolates. Four of them were classified as clade 8 through the screening for 23 SNPs; the two human isolates grouped in this clade as well, while two strains were closely related to strains representing clade 6. To assess the pathogenicity of these strains, we assayed correlates of virulence. Shiga toxin production was determined by an ELISA kit. Four strains were high producers and one of these strains that belonged to a novel genotype showed high verocytotoxic activity in cultured cells. Also, these clade 8 and 6 strains showed high RBC lysis and adherence to epithelial cells. One of the clade 6 strains showed stronger inhibition of normal water absorption than E. coli O157:H7 EDL933 in human colonic explants. In addition, two of the strains showing high levels of Stx2 production and RBC lysis activity were associated with lethality and uremia in a mouse model. Consequently, circulation of such strains in cattle may partially contribute to the high incidence of HUS in Argentina.     

Mutations in DOCK7 in Individuals with Epileptic Encephalopathy and Cortical Blindness

Epileptic encephalopathies are increasingly thought to be of genetic origin, although the exact etiology remains uncertain in many cases. We describe here three girls from two nonconsanguineous families affected by a clinical entity characterized by dysmorphic features, early-onset intractable epilepsy, intellectual disability, and cortical blindness. In individuals from each family, brain imaging also showed specific changes, including an abnormally marked pontobulbar sulcus and abnormal signals (T2 hyperintensities) and atrophy in the occipital lobe. Exome sequencing performed in the first family did not reveal any gene with rare homozygous variants shared by both affected siblings. It did, however, show one gene, DOCK7, with two rare heterozygous variants (c.2510delA [p.Asp837Alafs^∗48] and c.3709C>T [p.Arg1237^∗]) found in both affected sisters. Exome sequencing performed in the proband of the second family also showed the presence of two rare heterozygous variants (c.983C>G [p.Ser328^∗] and c.6232G>T [p.Glu2078^∗]) in DOCK7. Sanger sequencing confirmed that all three individuals are compound heterozygotes for these truncating mutations in DOCK7. These mutations have not been observed in public SNP databases and are predicted to abolish domains critical for DOCK7 function. DOCK7 codes for a Rac guanine nucleotide exchange factor that has been implicated in the genesis and polarization of newborn pyramidal neurons and in the morphological differentiation of GABAergic interneurons in the developing cortex. All together, these observations suggest that loss of DOCK7 function causes a syndromic form of epileptic encephalopathy by affecting multiple neuronal processes.     

Biology and conservation of freshwater bivalves: past,present and future perspectives

Freshwater bivalves have been highly threatened by human activities, and recently their global decline has been causing conservational and social concern. In this paper, we review the most important research events in freshwater bivalve biology calling attention to the main scientific achievements. A great bias exists in the research effort, with much more information available for bivalve species belonging to the Unionida in comparison to other groups. The same is true for the origin of these studies, since the publishing pattern does not always correspond to the hotspots of biodiversity but is concentrated in the northern hemisphere mainly in North America, Europe and Russia, with regions such as Africa and Southeast Asia being quite understudied. We also summarize information about past, present and future perspectives concerning the most important research topics that include taxonomy, systematics, anatomy, physiology, ecology and conservation of freshwater bivalves. Finally, we introduce the articles published in this Hydrobiologia special issue related with the International Meeting on Biology and Conservation of Freshwater Bivalves held in 2012 in Bragança, Portugal.     

The Cdk5 Kinase Downregulates ATP-Gated Ionotropic P2X<Subscript>3</Subscript> Receptor Function Via Serine Phosphorylation

Cdk5 is an endogenous kinase activated by the neuronal-specific protein p35 and implicated in multiple neuronal functions, including modulation of certain pain responses. We investigated whether Cdk5 could regulate ATP-gated P2X₃ receptors that are members of the family of membrane proteins expressed by sensory neurons to transduce nociception in baseline and chronic pain. To study the potential P2X₃ receptor modulation by Cdk5, we co-transfected rat P2X₃ receptors and Cdk5 into HEK cells and observed increased P2X₃ receptor serine phosphorylation together with downregulation of receptor currents only when these genes were transfected together with the gene of the Cdk5 activator p35. The changes in receptor responses were limited to depressed current amplitude as desensitization and recovery were not altered. Transfection of p35 with P2X₃ similarly downregulated receptor responses, suggesting that this phenomenon could be observed even with constitutive Cdk5. The present data indicate a novel target to express the action of Cdk5 on membrane proteins involved in pain perception.     

A behavioural scale to measure ease of farrowing in sows

Farrowing is one of the most critical phases in pig production, as it has an impact on neonatal pig survival. Assessing the ease of farrowing can improve the management of sows and thus increase litter survival. The aims of this study were: 1) to develop an ease of farrowing score (EFS) in sows based on the behaviour of the sows and their piglets, and 2) to determine the relationship between the EFS and productive, physiological, and subjective parameters. Eighty hybrid (Large White × Landrace) sows from first to seventh parity housed in individual crates were used. An EFS was constructed using the total duration of farrowing, the birth interval, the total time standing or sitting, the number of position changes during the day before and the day of farrowing, the sow posture at birth, the viability and the position of the piglets at birth (head or back born). Moreover, rectal temperature at 90 min after farrowing, a four categorical subjective visual assessment (VA) of farrowing and litter size (piglets born alive, stillborn and mummified foetus) were recorded. A common factor analysis model yielded five factors with an eigenvalue higher than 0.95 that accounted for 75.05% of the total variation between individuals. The three main factors were “farrowing duration”, “sow posture”, and “sow activity” of sows and explained 23.44%, 15.67%, and 14.23% of the variance, respectively. Primiparous sows had higher values for factor 3 (sow activity) than multiparous sows (P = 0.02). Sows without stillborn or mummification foetus showed higher values of EFS than sows with at least one stillborn or mummification foetus (P = 0.06 and 0.01, respectively). Sows that received a visual assessment of 3 and 4 showed higher values of EFS than sows that received a VA of 1 and 2 (P = 0.0017). The EFS appears to be a good behavioural scale to measure ease of farrowing in sows kept in individual farrowing crates. Duration of farrowing, sow position, and presence of stillborn piglets and mummified foetuses appear to be important ease of farrowing indicators.     

The virus as metabolic engineer

Recent genome-wide screens of host genetic requirements for viral infection have reemphasized the critical role of host metabolism in enabling the production of viral particles. In this review, we highlight the metabolic aspects of viral infection found in these studies, and focus on the opportunities these requirements present for metabolic engineers. In particular, the objectives and approaches that metabolic engineers use are readily comparable to the behaviors exhibited by viruses during infection. As a result, metabolic engineers have a unique perspective that could lead to novel and effective methods to combat viral infection.     

Acetylcholinesterase inhibitory activity of lycopodane-type alkaloids from the Icelandic Lycopodium annotinum ssp. alpestre

The aim of this study was to investigate structures and acetylcholinesterase inhibitory activities of lycopodane-type alkaloids isolated from an Icelandic collection of Lycopodium annotinum ssp. alpestre. Ten alkaloids were isolated, including annotinine, annotine, lycodoline, lycoposerramine M, anhydrolycodoline, gnidioidine, lycofoline, lannotinidine D, and acrifoline, as well as a previously unknown N-oxide of annotine. ¹H and ¹³C NMR data of several of the alkaloids were provided for the first time. Solvent-dependent equilibrium constants between ketone and hemiketal form of acrifoline were determined. Conformation of acrifoline was characterized using NOESY spectroscopy and molecular modelling. The isolated alkaloids were evaluated for their in vitro inhibitory activity against acetylcholinesterase and butyrylcholinesterase. Ligand docking studies based on mutated 3D structure of Torpedo californica acetylcholinesterase provided rationale for low inhibitory activity of the isolated alkaloids as compared to huperzine A or B, which are potent acetylcholinesterase inhibitors belonging to the lycodine class. Based on the modelling studies the lycopodane-type alkaloids seem to fit well into the active site gorge of the enzyme but the position of their functional groups is not compatible with establishing strong hydrogen bonding interactions with the amino acid residues that line the binding site. The docking studies indicate possibilities of additional functionalization of the lycopodane skeleton to render potentially more active analogues.     

Resistance of tomato genotypes to the greenhouse whitefly Trialeurodes vaporariorum (West.) (Hemiptera: Aleyrodidae)

The greenhouse whitefly, Trialeurodes vaporariorum Westwood, is the most common and abundant whitefly in Argentine horticultural greenhouse crops, especially in tomato (Solanum lycopersicum). Resistance in some wild tomato relatives, such as S. peruvianum, S. habrochaites and S. pennellii to the greenhouse whitefly has been described. The Mi gene confers effective resistance against several species of insects, among them the sweet potato whitefly, Bemisia tabaci Gennadius. Resistance to T. vaporariorum was found in the prebreeding line FCN 93-6-2, derived from a cross between S. lycopersicum cultivar Uco Plata INTA (MiMi) and the wild line FCN 3-5 S. habrochaites. The purpose of this study was to evaluate resistance to T. vaporariorum in tomato genotypes and to study the relationship between this resistance and the presence of the REX-1 marker, which is linked to the Mi gene. In a free-choice assay, the average number of adults per leaf and the number of immatures on the middle and basal plant parts were analyzed. In a no-choice assay, the oviposition rate and adult survival rate were calculated. For all variables analyzed, FCN 3-5 was the most resistant strain. Variations were found in the F2 progeny between the prebreeding line FCN 13-1-6-1 and cv. Uco Plata INTA. Results from the F2 progeny indicate that resistance to T. vaporariorum may be polygenic with transgressive segregation. Whitefly resistance was found to be independent of the REX-1 marker.     

Galactan sulfate of Grateloupia indica: Isolation, structural features and antiviral activity

Natural compounds offer interesting pharmacological perspectives for antiviral drug development with regard to broad-spectrum antiviral properties and novel modes of action. In this study, we have analyzed polysaccharide fractions isolated from Grateloupia indica. The crude water extract (GiWE) as well as one fraction (F3) obtained by anion exchange chromatography had potent anti-HSV activity. Their inhibitory concentration 50% (IC₅₀) values (0.12-1.06 μg/ml) were much lower than cytotoxic concentration 50% values (>850 μg/ml). These fractions, which were effective antiviral inhibitors if added only during the adsorption period, had very low anticoagulant activity. Furthermore, they had no direct inactivating effect on virions in a virucidal assay. Chemical, chromatographic and spectroscopic methods showed that the active polysaccharide, which has an apparent molecular mass of 60 kDa and negative specific rotation −16° (c 0.2, H₂O), contains α-(1 → 4)- and α-(1 → 3)-linked galactopyranose residues. Sulfate groups, if present, are located mostly at C-2/6 of (1 → 4)- and C-4/6 of (1 → 3)-linked galactopyranosyl units, and are essential for the anti herpetic activity of this polymer.