Sunday, January 16, 2011

Not quite Jurassic Park, but close.

15,000 years ago, North America was close to unrecognizable. Most of modern-day Canada and parts of what is now the United States were covered by glaciers and temperatures elsewhere easily averaged below freezing. In the midwest, enormous mammals and birds reigned supreme. One of the most well-known of these massive species was the wooly mammoth. Their stature is believed to have been comparable to today's elephants; however, their hind legs were significantly shorter than their front legs, their colossal ivory tusks often measured over 13 feet in length, and, as you may have guessed, they were exceptionally hairy. Now, Japanese scientists have hatched a plan to bring this ancient beast back to life.

Back in 1996, researchers shocked the world when they unveiled Dolly, the very first test-tube ewe. Dolly lived to be six years old, and has long been hailed as the ultimate triumph of biotechnology. But can the same be done with an extinct species from the last ice age? Allegedly yes, through the process of somatic cell nuclear transfer (SCNT).

In SCNT, scientists extract an egg cell from a live animal and remove its nucleus, replacing it with the nucleus of a somatic cell (a somatic cell is any cell not from a sex organ). Somatic cells are diploid cells, meaning that they have two copies of genetic material from the parent animals. Germ cells, such as egg cells, are called haploid because they only have one copy. Replacing the nuclear material from an egg cell with that of a somatic cell is therefore an effective simulation of fertilization. Once the egg has been modified, it can then be implanted in a surrogate uterus, where it divides to form an embryo.

The research team hopes to isolate an intact somatic cell from frozen remains of a wooly mammoth. Within five or six years, they plan to successfully replace the nucleus of an elephant's egg cell with the nucleus of this preserved mammoth cell, implant it into the uterus of an elephant, and wait patiently for the birth of an animal that has not existed since humanity's first predecessors roamed the earth. No sweat. For some biologists, raising the dead is all in a day's work.

Saturday, January 15, 2011

The greatest story ever told.

13.7 billion years ago, an event occurred. Space itself swelled terrifically into being. Suddenly, there appeared a burgeoning cosmos where before there had been nothing. The explosion left behind a molten sea of charged particles that would eventually give life to everything in the universe. The churning plasma expanded along with space for 300,000 years until its constituent protons and electrons had finally cooled enough to combine. Consequently, the entire universe was soon clouded by neutral hydrogen gas. Such gas absorbs radiation exceptionally well, and so space was plunged into darkness for another billion or so years.

At this point, it was gravity that dispelled the haze. Clumps of gas soon condensed under its influence, slowly becoming dense furnaces for nuclear fusion. The high energy UV radiation emitted by these young stars leaked out across the universe, heating the surrounding gas to temperatures they had not faced since the big bang. Electrons that had been trapped within the nuclei of light atoms were suddenly released, reionizing hydrogen and rendering space transparent once more. As the universe expanded, overdense regions of structure contracted under gravity. Over the course of a few billion years, a familiar cosmos took shape. Stars came together into galaxies, galaxies came together into clusters, wacky objects like quasars came and went, supernovae went off, our Solar System formed, and the universe painstakingly plodded into its current configuration.

You may have noticed that some details are a little murky. As of yet, astronomers have no idea how the first stars formed out of the ambient fog. One pair of scientists is now hoping to change that. Alan Rogers of MIT and Judd Bowman of Arizona State University have developed a method using the 21cm spectral line of hydrogen. This line appears in the spectra of hydrogen atoms that have undergone an excitation. According to Rogers and Bowman, the specific way in which the radio spectrum of hydrogen evolves with time tells us that reionization itself lasted about 5 million years. Thus, the first stars and galaxies were most likely born during this time. Understanding the stellar mechanics that occurred during reionization is one of the most active quests in cosmology today. The team hopes to learn more with future observation and fine-tuning of their instrument, the EDGES antenna at the MIT Haystack Observatory.