Assessment of antibodies against three zoonotic bacteria and associated risk factors in pig farms in Colombia. / Evaluación de anticuerpos frente a tres bacterias zoonóticas y factores de riesgo asociados en explotaciones porcinas de Colombia.

The aim of this study was to determine the seroprevalence of Salmonella spp., Mycobacterium bovis and Brucella spp., together with associated risk factors, in pigs from various farms in seven regions of Colombia. A total of 350 blood samples were obtained from pigs at different stages in the production cycle of 23 farms, which were tested using the enzyme-linked immunosorbent assay (ELISA) diagnostic kits Pigtype®-Salmonella Ab (Qiagen®, Hilden, Germany), INgezim TB porcine and INgezim Brucella porcine (Ingenasa®, Madrid, Spain). The overall seroprevalence for Salmonella spp. was 42.85% (n = 150) and, for M. bovis, it was 5.42% (n = 19). No positive samples were detected for Brucella spp. In the farms evaluated, the presence of pests, such as rodents, was found to be the management variable with a statistically significant association with seropositivity for Salmonella spp. and M. bovis. The results suggest that, at some point in the primary production cycle, pigs came into contact with zoonotic bacteria, resulting in seropositivity, which may pose a risk to public health and national pig production.

Les auteurs présentent les résultats d'une étude menée en Colombie pour déterminer la prévalence sérologique de Salmonella spp., de Mycobacterium bovis et de Brucella spp. et d'identifier les facteurs de risques associés chez les porcs de différents élevages répartis dans sept régions du pays. Au total, 350 prélèvements sanguins de porcs en différentes phases du cycle de production et provenant de 23 exploitations ont été analysés en utilisant les kits de diagnostic suivants : test immuno-enzymatique (ELISA) Pigtype®-Salmonella Ab (Qiagen®, Hilden, Allemagne), INgezim TB porcina et INgezim Brucella porcina (Ingenasa®, Madrid, Espagne). La prévalence sérologique globale de Salmonella spp. était de 42,85 % (n = 150) et celle de M. bovis de 5,42 % (n = 19) ; aucun échantillon n'a été trouvé positif pour Brucella spp. En ce qui concerne les facteurs en lien avec la gestion des élevages, une corrélation significative au plan statistique a été observée dans les exploitations étudiées entre la présence de ravageurs (rongeurs notamment) et l'apparition d'anticorps dirigés contre Salmonella spp. et M. bovis. Les résultats obtenus laissent penser que les porcs ont été exposés à ces bactéries zoonotiques à un moment ou un autre du cycle de production primaire, ce qui a déclenché l'apparition d'anticorps ; il s'agit d'une situation à risque tant pour la santé publique que pour la filière porcine du pays.

El objetivo del presente estudio fue determinar la seroprevalencia respectoa Salmonella spp., Mycobacterium bovis y Brucella spp., junto con los factores de riesgo asociados, en porcinos de diferentes explotaciones de producción en siete regiones de Colombia. Se obtuvieron 350 muestras sanguíneas de porcinos de diferentes etapas del ciclo productivo provenientes de 23 explotaciones,y estas fueron analizadas utilizando los estuches de ensayo inmunoenzimático (ELISA) para diagnóstico Pigtype®-Salmonella Ab (Qiagen®, Hilden, Alemania), INgezim TB porcina e INgezim Brucella porcina (Ingenasa®, Madrid, España). La seroprevalencia general respecto a Salmonella spp. fue del 42,85% (n = 150),y para M. bovis, del 5,42% (n = 19); no se detectó ninguna muestra positiva respecto a Brucella spp. Se determinó que en las explotaciones evaluadas, la presencia de plagas, como los roedores, fue la variable de manejo con asociación estadísticamente significativa a la seropositividad respecto a Salmonella spp.y a M. bovis. Los resultados obtenidos sugieren que, en algún momento del ciclo de producción primaria, los cerdos estuvieron en contacto con las bacterias zoonóticas frente a las que se obtuvo seropositividad, lo cual puede representar un riesgo para la salud pública y la producción porcina a nivel nacional.

A T42A Ran mutation: differential interactions with effectors and regulators, and defect in nuclear protein import.

Ran, the small, predominantly nuclear GTPase, has been implicated in the regulation of a variety of cellular processes including cell cycle progression, nuclear-cytoplasmic trafficking of RNA and protein, nuclear structure, and DNA synthesis. It is not known whether Ran functions directly in each process or whether many of its roles may be secondary to a direct role in only one, for example, nuclear protein import. To identify biochemical links between Ran and its functional target(s), we have generated and examined the properties of a putative Ran effector mutation, T42A-Ran. T42A-Ran binds guanine nucleotides as well as wild-type Ran and responds as well as wild-type Ran to GTP or GDP exchange stimulated by the Ran-specific guanine nucleotide exchange factor, RCC1. T42A-Ran.GDP also retains the ability to bind p10/NTF2, a component of the nuclear import pathway. In contrast to wild-type Ran, T42A-Ran.GTP binds very weakly or not detectably to three proposed Ran effectors, Ran-binding protein 1 (RanBP1), Ran-binding protein 2 (RanBP2, a nucleoporin), and karyopherin beta (a component of the nuclear protein import pathway), and is not stimulated to hydrolyze bound GTP by Ran GTPase-activating protein, RanGAP1. Also in contrast to wild-type Ran, T42A-Ran does not stimulate nuclear protein import in a digitonin permeabilized cell assay and also inhibits wild-type Ran function in this system. However, the T42A mutation does not block the docking of karyophilic substrates at the nuclear pore. These properties of T42A-Ran are consistent with its classification as an effector mutant and define the exposed region of Ran containing the mutation as a probable effector loop.

Differential expression of the H-ras mutated and normal alleles in rabbit DMBA-induced keratoacanthomas.

Keratoacanthomas (KAs) are benign and self-regressing tumors in which a high incidence of the mutated H-ras oncogene has been observed both in humans and in experimental models. To determine the level of expression of the mutated H-ras allele with respect to its normal counterpart in 7,12-dimethylbenz(a)anthracene (DMBA)-induced KAs in rabbit skin, we have utilized a quantitative technique based on reverse transcription polymerase chain reaction (RT-PCR) and selective cleavage of the mutated molecules of the H-ras gene. Analysis of 16 KAs showed that the mutated H-ras transcripts were up to 3-fold more abundant than the non-mutated H-ras transcript in the different tumors. This higher expression of the mutated allele appears to correlate with increased differentiation in the KAs and in turn may contribute to tumor regression.

Separate domains of the Ran GTPase interact with different factors to regulate nuclear protein import and RNA processing.

The small Ras-related GTP binding and hydrolyzing protein Ran has been implicated in a variety of processes, including cell cycle progression, DNA synthesis, RNA processing, and nuclear-cytosolic trafficking of both RNA and proteins. Like other small GTPases, Ran appears to function as a switch: Ran-GTP and Ran-GDP levels are regulated both by guanine nucleotide exchange factors and GTPase activating proteins, and Ran-GTP and Ran-GDP interact differentially with one or more effectors. One such putative effector, Ran-binding protein 1 (RanBP1), interacts selectively with Ran-GTP. Ran proteins contain a diagnostic short, acidic, carboxyl-terminal domain, DEDDDL, which, at least in the case of human Ran, is required for its role in cell cycle regulation. We show here that this domain is required for the interaction between Ran and RanBP1 but not for the interaction between Ran and a Ran guanine nucleotide exchange factor or between Ran and a Ran GTPase activating protein. In addition, Ran lacking this carboxyl-terminal domain functions normally in an in vitro nuclear protein import assay. We also show that RanBP1 interacts with the mammalian homolog of yeast protein RNA1, a protein involved in RNA transport and processing. These results are consistent with the hypothesis that Ran functions directly in at least two pathways, one, dependent on RanBP1, that affects cell cycle progression and RNA export, and another, independent of RanBP1, that affects nuclear protein import.

The adenovirus tripartite leader may eliminate the requirement for cap-binding protein complex during translation initiation.

The adenovirus tripartite leader is a 200-nucleotide 5' noncoding region that is found on all late viral mRNAs. This segment is required for preferential translation of viral mRNAs at late times during infection. Most tripartite leader-containing mRNAs appear to exhibit little if any requirement for intact cap-binding protein complex, a property previously established only for uncapped poliovirus mRNAs and capped mRNAs with minimal secondary structure. The tripartite leader also permits the translation of mRNAs in poliovirus-infected cells in the apparent absence of active cap-binding protein complex and does not require any adenovirus gene products for this activity. The preferential translation of viral late mRNAs may involve this unusual property.

Silver staining of the nucleolar organizer regions (NORs) in semithin Lowicryl sections.

The one-step silver technique was applied to semithin Lowicryl sections of root meristem cells of Allium cepa and a human tumor cell line (TG cells). In vegetal cells, after 5 min of staining reaction, the Ag-NOR proteins formed ring-shaped structures peripherally within the nucleolus. In animal cells silver granules were distributed over the entire nucleolus. The specificity of the staining reaction was increased by incubation of the sections in NH4Cl and Schiff's reagent prior to Ag-NOR silver staining.

[Characterization of an inhibitor of glucose-6-phosphate dehydrogenase]. / Caracterización de un inhibidor de la G6PDH.

A strong inhibitor of G6PDH has been detected in rat liver homogenates. The inhibitor, isolated by ultrafiltration methods, proved to be very stable under incubation with trypsin and high temperatures. Gel-filtration through Sephadex G-75 showed it to have a molecular weight of 3,500 daltons, though perchloric acid treatment produced a light form of 900 daltons. Both forms of inhibitor act as competitive inhibitor with respect to G6P and exhibit non-competitive inhibition pattern with respect to NADP+. Physical and kinetic properties, and the increase of G6PDH activity at low NADP+ concentrations, in the presence of NADPH and inhibitor or palmitoyl-CoA, in relation to the G6PDH activity in presence of NADPH, lead to the identification of the low-molecular weight inhibitor as palmitoyl-CoA.