Viaje a las profundidades del Océano (VIDEO) + Extrañas criaturas marinas (FOTOS)

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  Pero, ¿qué es un Océano? U n océano es una enorme masa de agua salada que representa un importante ecosistema para el equilibrio ecológico de la Tierra y que constituye el  71% de la superficie terrestre , gracias a los 360,132,000 km² de su extensión. Y,  ¿cuántos océanos existen? Lo que cubre gran parte de la superficie de la Tierra, es en sí, un solo océano. Es decir, una sola masa de agua. Para un mejor estudio, el hombre dividió esta enorme masa en 5 partes de acuerdo a su ubicación geográfica. Por ello, la expresión “los océanos”, es correcta. Importancia de los océanos *Absorben entre un 25 y 30% del dióxido de carbono emitido a la atmósfera, por lo que Equilibran el clima de toda la Tierra. *Representan numerosos ecosistemas para diversas formas de vida animal, vegetal, bacteriana, protista y fúngica. *Son hogar para miles de especies, conocidas y aún desconocidas. Existen aproximadamente 250,000 especies conocidas, pero se cree que puedan haber 750,000 más. *Proveen fuentes

Human brain cells boost Mouse memory

Mice with human cells grafted into their brains outperform their normal counterparts on tests of learning and memory, according to new research.

The findings, published today in the journal Cell Stem Cell, suggest that evolution of the human brain involved a major upgrade to long-neglected cells called Astrocytes (see image below), and could provide a better way of testing potential treatments for neurological and psychiatric diseases.

Astrocytes are one of several types of Glia, the non-neuronal cells found alongside neurons in the nervous system.

Maiken Nedergaard, Steve Goldman and their colleagues of the University of Rochester Medical Centre in New York isolated Glial cell progenitors – the stem cells that generate astrocytes – from aborted human foetuses, labelled them with fluorescent green protein, and then grafted them into the brains of newborn mice.

The mice endowed with human cells learned to associate a mild electric shock with a particular sound or location in their environment far more quickly than another group of animals which received grafts of mouse cells.

They also learned their way through a maze about twice as fast, and were better at recognizing familiar objects when they were placed in unusual location.

The technique of grafting human cells into mouse brains could improve the way in which researchers test potential treatments for a host of neurological and psychiatric diseases. "We can also generate glial progenitor cells from human skin cells reprogrammed into induced pluripotent stem cells," says Goldman.

"As a result, we can now establish glial progenitor cells from individuals with brain diseases," he says, "and we have already established chimeric mice containing glia from patients with schizophrenia." Such chimeras would be better for evaluating new drugs as they because they would bear a much closer resemblance to humans than existing mouse models.
Source: The Guardian

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