It is has been shown that the majority of T. cruzi strains isolated from Mexico belong to the T. cruzi I (TCI). The immune response produced in response to Mexican T. cruzi I strains has not been well characterized. In this study, two Mexican T. cruzi I strains were used to infect Balb/c mice. The Queretaro (TBAR/MX/0000/Queretaro)(Qro) strain resulted in 100% mortality. In contrast, no mortality was observed in mice infected with the Ninoa (MHOM/MX/1994/Ninoa) strain. Both strains produced extended lymphocyte infiltrates in cardiac tissue. Ninoa infection induced a diverse humoral response with a higher variety of immunoglobulin isotypes than were found in Qro-infected mice. Also, a stronger inflammatory TH1 response, represented by IL-12p40, IFNγ, RANTES, MIG, MIP-1β, and MCP-1 production was observed in Qro-infected mice when compared with Ninoa-infected mice. We propose that an exacerbated TH1 immune response is a likely cause of pathological damage observed in cardiac tissue and the primary cause of death in Qro-infected mice.

The causes of late-Holocene centennial to millennial scale climatic variability and the impact that such variability had on tropical ecosystems are still poorly understood. Here, we present a highresolution, multiproxy record from lowland eastern Mesoamerica, studied to reconstruct climate and vegetation history during the last 2,000 years, in particular to evaluate the response of tropical vegetation to the cooling event of the Little Ice Age (LIA). Our data provide evidence that the densest tropical forest cover and the deepest lake of the last two millennia were coeval with the LIA, with two deep lake phases that follow the Spö rer and Maunder minima in solar activity. The high tropical pollen accumulation rates limit LIA's winter cooling to a maximum of 2°C. Tropical vegetation expansion during the LIA is best explained by a reduction in the extent of the dry season as a consequence of increased meridional flow leading to higher winter precipitation. These results highlight the importance of seasonal responses to climatic variability, a factor that could be of relevance when evaluating the impact of recent climate change.climate variability ͉ Late Holocene ͉ Mexico ͉ seasonality ͉ tropical ecosystems T he Little Ice Age (LIA) (1350-1850 A.D.) has been identified as one of the most important climatic oscillations of the late Holocene and the last of several centennial to millennial scale Holocene cooling events centered over the North Atlantic (1-4). Low-latitude cooling during the LIA is evident from tropical glacier advances (5, 6), and reduced sea-surface temperatures in the Caribbean (7-9). Dry LIA conditions in the Caribbean are relatively well documented and explained by a change in the position of the Intertropical Convergence Zone (ITCZ) (10, 11), but little is known about the impact that this climatic event had on the lowland tropical ecosystems of the Americas. Lago Verde, near the coast of the Gulf of Mexico (Fig. 1), is a highly sensitive record of recent climate change (12,13) where the response of the tropical vegetation and the lake system to the LIA cooling can be clearly traced, without any significant human impact. Multiproxy data from this lake show that in this tropical region the LIA is recorded by the deepest lake level and the densest forest cover of the last two millennia. In this article, we present arguments evaluating the role of solar forcing as an important element explaining climatic variability in the tropics and the North Atlantic region. We also discuss the role of regional moisture balance as a condition for the expression of regional precipitation trends, and, finally, we present an argument about the importance that changes in the seasonality of precipitation can have over the Gulf of Mexico coastal region, mitigating the dry LIA trend recorded in some areas of the Caribbean. Study SiteThis study is based mainly on pollen, charcoal particles, and diatom analyses on the sediment record from Lago Verde, a small, closed-basin lake at 200 m above sea level, on the outskirts of ...

Normal and cancerous prostate cells can take up iodine, and depending on the chemical form, it exerts antiproliferative and apoptotic effects both in vitro and in vivo.

Past research syntheses provided evidence that personality traits are both stable and changeable throughout the lifespan. However, early meta-analytic estimates were constrained by a relatively small universe of longitudinal studies, many of which tracked personality traits in small samples over moderate time periods using measures that were only loosely related to contemporary trait models such as the Big Five. Since then, hundreds of new studies have emerged allowing for more precise estimates of personality trait stability and change across the lifespan. Here, we updated and extended previous research syntheses on personality trait development by synthesizing novel longitudinal data on rank-order stability (total k = 189, total N = 178,503) and mean-level change (total k = 276, N = 242,542) from studies published after January 1st 2005. Consistent with earlier meta-analytic findings, the rank-order stability of personality traits increased significantly throughout early life before reaching a plateau in young adulthood. These increases in stability coincide with mean-level changes in the direction of greater maturity. In contrast to previous findings, we found little evidence for increasing rank-order stabilities after age 25. Moreover, cumulative mean-level trait changes across the lifespan were slightly smaller than previously estimated. Emotional stability, however, increased consistently and more substantially across the lifespan than previously found. Moderator analyses indicated that narrow facet-level and maladaptive trait measures were less stable than broader domain and adaptive trait measures. Overall, the present findings draw a more precise picture of the lifespan development of personality traits and highlight important gaps in the personality development literature.

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