The role of the coastal oceans on the seasonal mean air temperature in Argentina

El objetivo de este trabajo es detectar la influencia de la temperatura de superficie del mar (TSM) de las zonas costeras de los océanos Atlántico y Pacífico, sobre la temperatura media estacional en Argentina. Para ello se consideró una región de estudio delimitada por 30-90º O y 20-60º S. Se obtuvieron patrones de variabilidad interanual de TSM estacional (de verano e invierno) a través de análisis de componentes principales (ACP) en modo T. Se calcularon correlaciones lineales entre las series de tiempo derivadas de este método y las de temperatura media simultánea pertenecientes a estaciones meteorológicas de Argentina. Algunos de los modos de variabilidad obtenidos mostraron relación con la temperatura media en gran parte del territorio argentino. Para evaluar la predictibilidad de la temperatura media utilizando dichos modos, se realizaron correlaciones desfasadas una estación. Los resultados mostraron un buen grado de predictibilidad para la temperatura de primavera a partir de los modos de variabilidad de TSM de invierno, pero para la temperatura de otoño no se encontró ninguna relación.This work aimed to detect the influence of the sea surface temperature (SST) of the coastal Atlantic and Pacific oceans on the seasonal mean air temperature in Argentina. The study region was delimited by 30-90º W and 20-60º S. Patterns of interannual variability of seasonal (summer and winter) SST were obtained through principal component analysis (PCA) in the T-mode. Linear correlations between time series derived from this method and the simultaneous mean air temperature series from weather stations were performed. Some of the variability modes obtained showed a relationship with mean air temperature over a large portion of Argentina. Lagged-by-one-season correlations were also made to assess the predictability of the mean temperature employing these modes. Results showed a reasonable degree of predictability in spring temperatures using winter SST variability modes, but for autumn temperatures, no relationship was found.Fil: Oliveri, Paula Carolina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; ArgentinaFil: González, Marcela Hebe. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones del Mar y la Atmósfera. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones del Mar y la Atmósfera; Argentin

Host-Parasite Interactions in Chagas Disease: Genetically Unidentical Isolates of a Single <i>Trypanosoma cruzi</i> Strain Identified <i>In Vitro via</i> LSSP-PCR

<div><p>The present study aims at establishing whether the diversity in pathogenesis within a genetically diverse host population infected with a single polyclonal strain of <i>Trypanosoma cruzi</i> is due to selection of specific subpopulations within the strain. For this purpose we infected Swiss mice, a genetically diverse population, with the polyclonal strain of <i>Trypanosoma cruzi</i> Berenice-78 and characterized <i>via</i> LSSP-PCR the kinetoplast DNA of subpopulations isolated from blood samples collected from the animals at various times after inoculation (3, 6 and 12 months after inoculation). We examined the biological behavior of the isolates in acellular medium and <i>in vitro</i> profiles of infectivity in Vero cell medium. We compared the characteristics of the isolates with the inoculating strain and with another strain, Berenice 62, isolated from the same patient 16 years earlier. We found that one of the isolates had intermediate behavior in comparison with Berenice-78 and Berenice-62 and a significantly different genetic profile by LSSP-PCR in comparison with the inoculating strain. We hereby demonstrate that genetically distinct <i>Trypanosoma cruzi</i> isolates may be obtained upon experimental murine infection with a single polyclonal <i>Trypanosoma cruzi</i> strain.</p></div

UPGMA.

<p>Phenogram constructed from UPGMA (Unweighted Pair Group Method using Arithmetic averages) resulting from the gene signature profile analysis obtained by LSSP-PCR of isolates obtained from hemocultures at 3 (Be-78is5-3mai, Be-78is21-3mai), 6 (Be-78is1-6mai; Be-78is2-6mai; Be-78is5-6mai; 78is15-6mai-Be) and 12 (Be-78is1-12mai; Be-78is15-12mai) months after infection of Swiss mice with 5000 blood trypomastigotes from Be-78 <i>Trypanosoma cruzi</i> strain in comparison with the Be-78 parental and Be-62 strains.</p

Hemocultures.

<p>Be-78: Berenice-78; is: isolate; MAI/mai: months after infection.</p><p>Repartition of the positive hemocultures from blood samples collected from mice infected with Berenice-78 <i>T</i>. <i>cruzi</i> strains at three, six and twelve months after infection.</p

Infectivity and <i>in vitro</i> development illustration.

<p>Representative photomicrographs of <i>in vitro</i> assay infection in Vero cell cultures with Berenice-62 and Berenice-78 parental strains and subpopulations/isolates of Be-78 strain, obtained from hemocultures at 3, 6 or 12 months after infection of Swiss mice with 5000 blood trypomastigotes from Be-78 <i>Trypanosoma cruzi</i> strain. After 18 hours exposure to the parasite, the cells were washed to remove extracellular parasites and maintained in medium until collection, fixed and stained at 24, 48 or 72 hours after inoculation. Increasing the rate of infectivity (asterisks) 48h after incubation for Be-62 strain (a, b, c) strain and for Be 78is5-3mai isolate (g, h, i); Increased rate of intracellular multiplication (asterisks) in 72h time for Be-78 parental strain (d, e, f); Infectivity and intracellular development profiles upper (asterisks) for isolate Be-78is2-6mai (j, k. G), and lower for Be-78is14-12mai (m, n, o). Fast Panotic. Bar = 25μm.</p

Infectivity and in vitro development.

<p><i>In vitro</i> infection assay in Vero cell cultures using Berenice-62 (grey square), Berenice-78 (parental, black square) strains and subpopulations/isolates of Be-78 strain, obtained from hemocultures at 3, 6 or 12 months after infection of Swiss mice with 5000 blood trypomastigotes from Be-78 <i>Trypanosoma cruzi</i> strain. After 18 exposure hours to the parasite, the cells were washed to remove extracellular parasites and maintained in medium until collection, fixation and staining 24 (solid bar), 48 (hatched bar) ou 72 (dotted bar) hours after inoculum. A) number of infected cells in 100 counted cells; B) number of intracellular amastigotes in 100 counted cells; C) number of intracellular parasites per infected cell. *: Significant difference compared to the 24 hours of culture; #: Significant difference compared to the 48 hours of culture; a: significant difference compared to the strain Be-62; b: significant difference compared to the Be-78 parental strain. The data represent the mean of triplicates ± standard error.</p

UPGMA.

<p>Phenogram constructed from UPGMA (Unweighted Pair Group Method using Arithmetic averages) resulting from the gene signature profile analysis obtained by LSSP-PCR of isolates obtained from hemocultures at 3 (Be-78is5-3mai, Be-78is21-3mai), 6 (Be-78is1-6mai; Be-78is2-6mai; Be-78is5-6mai; 78is15-6mai-Be) and 12 (Be-78is1-12mai; Be-78is15-12mai) months after infection of Swiss mice with 5000 blood trypomastigotes from Be-78 <i>Trypanosoma cruzi</i> strain in comparison with the Be-78 parental and Be-62 strains.</p

Growth kinetics in acellular culture medium.

<p>Growth kinetics of epimastigotes in LIT medium from days 0 to 20 of the parasites isolates obtained from hemoculture at 3, 6 or 12 months after infection of Swiss mice with 5000 blood trypomastigotes from Be-78 <i>Trypanosoma cruzi</i> strain. The Y-axis represents the number of parasites triplicate median x 10⁷/ml and the X axis represents the days of culture. The isolates’ growth curves (hatched line) are presented in comparison with the curves of the strain used in the inoculum (Berenice-78 parental: continous black lineBe-78) and of Berenice-62 strain (continous grey line Be-62).</p