¿Están vivos o no?

Most viruses travel light. They carry only a handful of genes for making new viruses, relying on their hosts' machinery to do the rest. But the newly identified virus, known as the Cafeteria roenbergensis virus, is a pack rat: It lugs around a staggering 730,000 base pairs of DNA, including more than 500 gene-like regions, researchers report online today in the Proceedings of the National Academy of Sciences. That makes it the largest marine virus known, with more DNA than some bacteria have. The researchers speculate that this virus—which infects Cafeteria roenbergensis, a predatory single-celled organism that eats other viruses and bacteria in the ocean—takes a more active role in making its proteins than do smaller viruses like HIV or herpesviruses. The only known virus that is larger, thought to be a close relative, infects a freshwater amoeba. Scientists typically don't classify viruses as living organisms, but giant viruses like these, with their own protein-making machinery and other functions normally carried out in living cells, blur the lines between what's alive and what isn't.

Origen de la vida

Llegará el momento en que abordemos el origen de la vida en clase, mientras tanto, podemos abrir boca con esta noticia publicada hace unos días. Nos habla de Titán una de las lunas de Saturno, donde al parecer, podrían darse las condiciones para la aparición de aminoácidos y nucleótidos (moléculas orgánicas imprescindibles para la aparición de la vida). Lo más sorprendente es que eso podría ocurrir en la atmósfera, cuando siempre hemos supuesto que eso sólo podría ocurrir en los océanos.

It's unlikely that the process produced Titanians, but experiments simulating the chemistry of the dense air on Saturn's biggest moon have yielded some of the basic buildings blocks of life. Scientists described how they used radio-frequency radiation—a more convenient substitute for ultraviolet sunlight—to turn methane, nitrogen, and carbon monoxide (the main constituents of Titan's atmosphere) into glycine and alanine, the two smallest amino acids. The experiments also produced cytosine, adenine, thymine, and guanine, the four most basic components of DNA. And they created uracil, a precursor of RNA. The researchers said that because they achieved the reactions without the presence of liquid water, it's possible life could have sprung forth on Earth not in the seas, as commonly assumed, but perhaps in the planet's early atmosphere—a considerably thinner version of the fog enveloping Titan today.