RESUMEN
Evidence of hot and cold igneous processes has been reported in small satellites and dwarf planets of the Solar System. Olivine and pyroxenes were detected in the spectral bands of both small satellites and dwarf planets. The aqueously altered form of olivine and serpentine has been detected in the spectrums of Ceres and Miranda hinting at possible hydrothermal processes in their interiors. Once more, the ubiquitous distribution of 26Al in the planetary nebula, then evolving in the protoplanetary disk, contributed to the primordial widespread heating. Volcanism, or cryovolcanism, then developed only in those bodies where long-lived radiogenic elements, and/or tidal processes, were available.
RESUMEN
Igneous processes were quite widespread in the small bodies of the Solar System (SBSS) and were initially fueled by short-lived radioisotopes, the proto-Sun, impact heating, and differentiation heating. Once they finished, long-lived radioisotopes continued to warm the active bodies of the Earth, (possibly) Venus, and the cryovolcanism of Enceladus. The widespread presence of olivine and pyroxenes in planets and also in SBSS suggests that they were not necessarily the product of igneous processes and they might have been recycled from previous nebular processes or entrained in comets from interstellar space. The difference in temperature between the inner and the outer Solar System has clearly favored thermal annealing of the olivine close to the proto-Sun. Transport of olivine within the Solar System probably occurred also due to protostellar jets and winds but the entrainment in SBSS from interstellar space would overcome the requirement of initial turbulent regime in the protoplanetary nebula.
RESUMEN
Hordeum vulgare, cultivated barley, and its wild relative, H. chilense, have several important traits that might be useful for wheat improvement. Here, in situ hybridization and barley expressed sequence tag (EST) markers were used to characterize and compare the chromosomes of H. chilense with those of H. vulgare. FISH with four repetitive DNA sequences, AG, AAG, 5S rDNA and 45S rDNA, was applied to the mitotic chromosomes of H. vulgare, H. chilense and available wheat-H. chilense addition and substitution lines. FISH with the AAG repeat differentiated the individual chromosomes of H. chilense and H. vulgare. The patterns of FISH signals in the two species differed greatly. The 45S rDNA signals were observed on two pairs of chromosomes in both species, while the 5S rDNA signals were observed on four pairs of chromosomes in H. vulgare and on one pair in H. chilense. The AG repeat showed FISH signals at the centromeric regions of all chromosomes of H. vulgare but none of the chromosomes of H. chilense. These results indicate that the chromosomes of the two species are highly differentiated. To study the homoeology between the two species, 209 EST markers of H. vulgare were allocated to individual chromosomes of H. chilense. One hundred and forty of the EST markers were allocated to respective chromosomes of H. chilense using the wheat-H. chilense addition and substitution lines. Twenty-six EST markers on average were allocated to each chromosome except to the chromosome 2H(ch)S, to which only 10 markers were allocated. Ninety percent of the allocated EST markers in H. chilense were placed on H. vulgare chromosomes of the same homo-eologous group, indicating that the expressed sequences of the two species were highly conserved. These EST markers would be useful for detecting chromatin introgressed from these species into the wheat genome.
Asunto(s)
Cromosomas de las Plantas/genética , Variación Genética , Hordeum/genética , Chile , Mapeo Cromosómico , Cartilla de ADN , ADN Ribosómico/genética , Etiquetas de Secuencia Expresada , Hibridación Fluorescente in Situ , Especificidad de la EspecieRESUMEN
In order to elucidate the global distribution of dioxins and related compounds, such as PCDDs, PCDFs and coplanar PCBs, levels of these compounds were determined in the muscle of skipjack tuna (Katsuwonus pelamis) collected from the offshore waters and open seas near Japan, Taiwan, Philippines, Indonesia, Seychelles and Brazil, and the Japan Sea, the East China Sea, the South China Sea, the Indian Ocean and the North Pacific Ocean. PCDDs, PCDFs and coplanar PCBs were detected in almost all the specimens collected from all the locations surveyed, indicating widespread contamination by these compounds in the marine environment. Higher concentrations of dioxins and coplanar PCBs were detected in the samples from temperate Asian regions, plausibly due to larger usage and anthropogenic generation in highly industrialized countries around the East China Sea and the South China Sea, such as Japan, Korea, Taiwan, Hong Kong and coastal China.