The Impacts of Inter-El Nino Variability on the Tropical Atlantic and Northeast Brazil Climate

In this study, observations and numerical simulations are used to investigate how different El Nino events affect the development of SST anomalies in the Atlantic and how this relates to the Brazilian northeast (NE) precipitation. The results show that different types of El Nino have different impacts on the SST anomalies of the equatorial and tropical South Atlantic but a similar SST response in the tropical North Atlantic. Strong and long (weak and short) El Ninos with the main heating source located in the eastern (central) Pacific generate cold (warm) anomalies in the cold tongue and Benguela upwelling regions during boreal winter and spring. When the SST anomalies in the eastern equatorial and tropical South Atlantic are cold (warm), the meridional SST gradient across the equator is positive (negative) and the ITCZ is not allowed (allowed) to move southward during the boreal spring; as a consequence, the precipitation is below (above) the average over the NE. Thus, strong and long (weak and short) El Ninos are followed by dry (wet) conditions in the NE. During strong and long El Ninos, changes in the Walker circulation over the Atlantic and in the Pacific-South Atlantic (PSA) wave train cause easterly wind anomalies in the western equatorial Atlantic, which in turn activate the Bjerknes mechanism, establishing the cold tongue in boreal spring and summer. These easterly anomalies are also responsible for the Benguela upwelling. During short and weak El Ninos, westerly wind anomalies are present in the western equatorial Atlantic accompanied by warm anomalies in the eastern equatorial and tropical South Atlantic; a positive phase of the South Atlantic dipole develops during boreal winter. The simulations highlight the importance of ocean dynamics in establishing the correct slope of the equatorial thermocline and SST anomalies, which in turn determine the correct rainfall response over the NE.

Germination rate and sporeling development of Chondracanthus chamissoi (Rhodophyta, Gigartinales) varies along a latitudinal gradient on the coast of Chile

Chondracanthus chamissoi (C. Agardh) Kutzing is an economically important red seaweed with an extended latitudinal distribution along the south-east Pacific. Here we report on the seasonal in vitro germination of carpospores and tetraspores from four populations distributed from 27 to 41 degrees S on the Chilean coast. Our results show that both types of spores exhibited a different physiological behavior related to the geographic origin of the specimens. Germination occurred throughout the year for both spore types in the four populations. However, for the northern locations (Calderilla, La Herradura and Puerto Aldea) germination was higher in spring, while for the southern location (Lechagua), germination was higher in summer. The growth rate of carposporelings and tetrasporelings varied seasonally in ail locations studied, with higher growth in spring. Among all, carposporelings from Lechagua specimens reached the highest growth rates (9.3 +/- 0.2% d(-1)). However, spores from Herradura and P. Aldea had a good germination and SGR in all seasons and would be good candidates to start spores-based cultivation of this valuable resource in Chile. (C) 2009 Elsevier B.V. All rights reserved

Influence of age on the development of immunological lung response in intrauterine undernourishment

Objective: We investigated the effect of intrauterine undernourishment on some features of asthma using a model of allergic lung inflammation in rats. The effects of age at which the rats were challenged (5 and 9 wk) were also evaluated. Methods: Intrauterine undernourished offspring were obtained from dams that were fed 50% of the nourished diet of counterparts and were immunized at 5 and 9 wk of age. They were tested for immunoglobulin E anti-ova titers (by passive cutaneous anaphylaxis), cell count in the bronchoal-veolar fluid, leukotriene concentration, airway reactivity, mucus production, and blood corticosterone and leptin concentrations 21 d, after immunologic challenge. Results: Intrauterine undernourishment significantly reduced the antigen-specific immunoglobulin E production, inflammatory cell infiltration into airways, mucus secretion, and production of leukotrienes B-4/C-4 in the lungs in both age groups compared with respective nourished rats. The increased reactivity to methacholine that follows antigen challenge was not affected by intrauterine undernourishment. Corticosterone levels increased with age in the undernourished rats` offspring, but not in the nourished rats` offspring. Undernourished offspring already presented high levels of corticosterone before inflammatory stimulus and were not modified by antigen challenge. Leptin levels increased with challenge in the nourished rats but not in the undernourished rats and could not be related to corticosterone levels in the. undernourished rats. Conclusion: Intrauterine undernourishment has a striking and age-dependent effect on the off spring, reducing lung allergic inflammation. (C) 2008 Elsevier Inc. All rights reserved.