The dynamics of erythrocyte infection in bovine anaplasmosis: a flow cytometry-based analysis.

Anaplasma marginale (A. marginale) is an obligate intracellular bacterium that infects bovine erythrocytes causing extravascular hemolysis and anemia. In the present work, we combine SYTO16 labeling of parasitized cells with the statistical power of flow cytometry to study the evolution of erythrocyte infection during bovine anaplasmosis.

Inhibition of connexin 43 in cardiac muscle during intense physical exercise.

Endurance training is accompanied by important adaptations in both cardiovascular and autonomic nervous systems. Previous works have shown that the main component of gap junctions in the ventricular myocardium (connexin 43 (Cx43) can be regulated by adrenergic stimulus. On the other hand, training raises vagal and decreases sympathetic tone, while augmenting myocardial sensitivity to sympathetic stimulation during exercise. We therefore evaluated the regulation of Cx43 expression by sympathetic tone during exercise in trained and sedentary mice. Training induced an increase in the protein level of Cx43 by 45-70% under resting conditions. The expression of Cx43 was inhibited in trained but not in untrained mice in response to a 60 min exercise bout. Normal basal expression was restored after 60 min of resting. Cx43 reached a minimum that was not different from basal expression in untrained mice. In accordance, electrocardiography and action potential analysis did not reveal major electrophysiological implications for the drop in Cx43 abundance in trained-exercise mice. We prevented Cx43 inhibition using propranolol, and observed increased basal mRNA levels of ß-adrenergic receptors without significant changes in the ratio ß1 to ß2. In conclusion, we showed that Cx43 expression is transiently inhibited by ß-adrenergic stimulus in trained mice during acute exercise.

A new set of molecular markers for the genotyping of Babesia bovis isolates.

Babesia bovis is a tick-borne apicomplexan pathogen that remains an important constraint for the development of cattle industries worldwide. The existence of different strains and subpopulations has long been described in this hemoparasite. However, few molecular markers have been reported for strain genotyping and characterization. Minisatellite sequences show high levels of variation and therefore provide excellent tools for both the genotyping and population genetic analysis. In this work we report a set of five molecular markers containing minisatellites that showed a variable degree of polymorphism in several American strains. We have used a bioinformatics approach to search for marker sequences contained in open reading frames. Five genes were chosen and primers were designed in conserved regions flanking the repeat region. Two of the genes were the previously described Bv80/Bb-1 and TRAP. The other three genes were named p200, Antigen 3 and Desmoyokin. Amplification by PCR, sequencing and comparative analysis of 11 strains from Argentina, Brazil, Uruguay, Mexico and USA determined that the tandem repeats varied in number and sequence among the isolates. Genome analysis of the five markers revealed that they were single copy and distributed across the four B. bovis chromosomes. When the new markers were analyzed in an experimental infection, absolute sequence conservation was found, indicating the stability of these markers during the course of infection. These markers were also stable during three syringe passages through calves. The application of this panel of molecular markers could provide new molecular tools for the genotyping of B. bovis isolates and analysis of changes in parasite populations following vaccination.