Many members of Archaea, a group of prokaryotes recognized three decades ago, colonize extreme environments; however, new research has shown that Archaeans are also abundant components of plankton in the open sea, where they play a key role in the biogeochemical cycles. Although the widespread distribution of Archaea in the marine environment is well documented there are no reports on the detection of Archaea in the Southwest Atlantic Ocean. During the search for picophytoplankton sequences using eukaryotic universal primers, we retrieved archaeal rDNA sequences from surface samples collected during the spring at a fixed monitoring station (EPEA) in the Argentine Sea. From environmental DNA and using PCR methodology, two DNA fragments of about 1700 and 1450 bp were visualized after electrophoresis in agarose gels, and separately purified, cloned, and sequenced. BLAST analysis showed that sequences of the highest size corresponded to eukaryotic organisms and, unexpectedly, those of about 1460 bp corresponded to archaeal organisms. Phylogenetic analysis showed that archaeal sequences belong to Euryarchaeota of marine group II, characterized as a methanogenic lineage. This is the first report on the presence of group II Euryarchaeota sequences in environmental water samples of the Argentine Sea. The fact that Archaea sequences were amplified with primers non-specific for this group may suggest an unexpected abundance of these organisms in the early spring in the Argentine Sea.

Muchos miembros de Archaea, un grupo de microroganismos descritos hace aproximadamente 30 años, colonizan ambientes extremos. Sin embargo, las investigaciones más recientes han demostrado que las arqueas también son abundantes componentes del plankton marino, siendo algunos grupos de Archaea componentes fundamentales de los ecosistemas marinos debido a su rol clave en los ciclos biogeoquímicos. Aunque la ubiquidad de las arqueas ha sido bien documentada, hasta el momento no hay registros de la presencia de representantes de este grupo en el mar Argentino. En un estudio de biodiversidad orientado a determinar secuencias de picoplancton utilizando cebadores universales para eucariotas, se encontraron secuencias de ADNr de Archaea en muestras recolectadas durante la primavera en una estación fija de monitorización (EPEA) en el mar Argentino. A partir de ADN ambiental y mediante el uso de la metodología de PCR, se obtuvieron dos fragmentos de aproximadamente 1700 y 1460 pb, que fueron separados y visualizados después de electroforesis en geles de agarosa y, luego, purificados, clonados y secuenciados. El análisis de BLAST mostró que las secuencias de tamaño superior correspondían a organismos eucariotas y las secuencias de menor tamaño pertenecían a Archaea. El análisis filogenético mostró que las secuencias de Archaea se agrupan con Euryarchaeota marina grupo II, caracterizado como un linaje metanógeno. Éste es el primer reporte de la presencia de secuencias de Euryarchaeota grupo II en aguas del mar Argentino. El hecho de que las secuencias de Archaea hayan sido amplificadas con cebadores no específicos para este grupo podría sugerir una inesperada abundancia de estos organismos durante los inicios de primavera en el mar Argentino.

A cross-sectional study on HIV/AIDS was carried out in 108 outpatients from the university hospital of the Federal University of Mato Grosso do Sul, Campo Grande, Brazil, from July to December 2008, to investigate latent tuberculosis infection using the tuberculin skin test (TST). The prevalence of positive results was 13.9%. The CD4+ T cell count (p = 0.091) and the diagnosis time (p = 0.010) were statistically significant when compared with TST positivity. In the cohort of HIV/AIDS patients who had latent tuberculosis infection, the median diagnosis time was eight years. Undetectable viral load presented significant association (p = 0.046) with tuberculosis infection. The fact that numerous individuals with HIV/AIDS infection presented a negative reaction to the tuberculin skin test is probably related to alterations in the cellular immune response induced by HIV infection. The tuberculin test is a useful tool for the detection of latent tuberculosis infection and should be performed in all HIV/AIDS individuals at the time of the diagnosis and on a yearly basis, if negative. Both the early identification of the tuberculosis infection by the tuberculin skin test at the moment of immunological restoration and chemoprophylaxis in infected individuals are mechanisms to control HIV/AIDS and tuberculosis coinfection.