Early Life On Earth: Could Salt Crusts Be Key Ingredient In Cooking Up Prebiotic Molecules?

ScienceDaily (Sep. 17, 2009) — German scientists investigating the complex chemical mixture thought to be present in the early Earth’s oceans have found that amino acids can be ‘cooked’ into many other important chemical building blocks of life when embedded in salt crusts.

Results of the laboratory experiments will be presented by Dr Stefan Fox at the European Planetary Science Congress in Potsdam, Germany, on Thursday 17 September.
Approximately 4.5 - 3.8 billion years ago, the Earth was probably covered by a salty ocean, rich in organic compounds, dotted with active volcanic islands and short-lived continents. The team from the University of Hohenheim in Stuttgart has simulated some of the chemical processes that might have taken place along hot volcanic coasts during this Hadean era by evaporating solutions of artificial primordial seawater and then baking the salty residue in an atmosphere of nitrogen and carbon dioxide to volcanic temperatures of 350 degrees Celsius. They found that compounds such as pyrroles, which are contained in chlorophyll and haeme (the oxygen-carrying component of haemoglobin), are created.
The group’s experiments show that interaction of amino acids with metal ions in the salt crusts fundamentally changes the thermal behaviour of the molecules, preventing them from turning into gas at high temperatures and allowing unexpected compounds to form.
“We embedded the amino acid DL-alanine in a salt crust mixture of sodium, calcium, potassium and magnesium chlorides and, after heating, we found that a compound formed with calcium salt chemically bonded to the amino acid. This particular compound has never been seen before and, although similar compounds are known to exist, we did not expect to see them in our experiments. This bond between the salt and the amino acid stabilises the compound at high temperatures and prevents sublimation. Without the bond, pyrroles would not be able to form,” said Dr Fox.
Amino acids are the chemical subunits of proteins. The amino acids present in the young Earth’s oceans would have been created in atmospheric reactions, perhaps during lightning discharges in clouds of volcanic ash, and there is increasing evidence that they would have been supplemented by impacting comets and meteorites. Although the concentration of amino acids in the primordial oceans would have been very small – about ten thousand times weaker than the salt concentrations – these reactions would have taken place over many hundreds of thousands of years, allowing significant concentrations of pyrroles to build up. Pyrroles are also created during volcanic eruptions, which were much more common during the Hadean era than today.
“Our aim is to identify types of small molecules that might have participated in a hypothetical next step of chemical evolution – the formation of energy driven networks of molecules that were the precursors to the first primitive electron-transfer and light-harvesting molecules. Our recent results show that amino acids, peptides and pyrroles could all have been present at this stage of the Earth’s evolution and would be good candidates for components of those networks,” said Fox.
These processes have important implications for Earth-like planets orbiting other stars, which may also be seeded with amino acids by impactors. A clear chemical pathway for the development of the raw materials of life would add support to the theory of life evolving beyond Earth.

A Biochemist Explains The Chemistry Of Cooking

January 1, 2009 — A biochemist and cook explains that cooking is all about chemistry and knowing some facts can help chefs understand why recipes go wrong. Because cooking is essentially a series of chemical reactions, it is helpful to know some basics. For example, plunging asparagus into boiling water causes the cells to pop and result in a brighter green. Longer cooking, however, causes the plant's cell walls to shrink and releases an acid. This turns the asparagus an unappetizing shade of grey.

You love to cook, but have you whipped up some disasters? Even the best recipes can sometimes go terribly wrong. A nationally recognized scientist and chef says knowing a little chemistry could help.
Long before she was a cook, Shirley Corriher was a biochemist. She says science is the key to understanding what goes right and wrong in the kitchen.
"Cooking is chemistry," said Corriher. "It's essentially chemical reactions."
This kind of chemistry happens when you put chopped red cabbage into a hot pan. Heat breaks down the red anthocyanine pigment, changing it from an acid to alkaline and causing the color change. Add some vinegar to increase the acidity, and the cabbage is red again. Baking soda will change it back to blue.
Cooking vegetables like asparagus causes a different kind of reaction when tiny air cells on the surface hit boiling water.
"If we plunge them into boiling water, we pop these cells, and they suddenly become much brighter green," Corriher said.
Longer cooking is not so good. It causes the plant's cell walls to shrink and release acid.
"So as it starts gushing out of the cells, and with acid in the water, it turns cooked green vegetables into [a] yucky army drab," Corriher said.
And that pretty fruit bowl on your counter? "Literally, overnight you can go from [a] nice green banana to an overripe banana," Corriher said.
The culprit here is ethylene gas. Given off by apples and even the bananas themselves, it can ruin your perfect fruit bowl -- but put an apple in a paper bag with an unripe avocado, and ethylene gas will work for you overnight.
"We use this as a quick way to ripen," Corriher said. Corriher says understanding a little chemistry can help any cook.
"You may still mess up, but you know why," she said. When it works, this kind of chemistry can be downright delicious.
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WHAT ARE ACIDS AND BASES? An acid is defined as a solution with more positive hydrogen ions than negative hydroxyl ions, which are made of one atom of oxygen and one of hydrogen. Acidity and basicity are measured on a scale called the pH scale. The value of freshly distilled water is seven, which indicates a neutral solution. A value of less than seven indicates an acid, and a value of more than seven indicates a base. Common acids include lemon juice and coffee, while common bases include ammonia and bleach.
WHY DOES FOOD SPOIL? Processing and improper storage practices can expose food items to heat or oxygen, which causes deterioration. In ancient times, salt was used to cure meats and fish to preserve them longer, while sugar was added to fruits to prevent spoilage. Certain herbs, spices and vinegar can also be used as preservatives, along with anti-oxidants, most notably Vitamins C and E. In processed foods, certain FDA-approved chemical additives also help extend shelf life.
This report has been produced thanks to a generous grant from the Camille and Henry Dreyfus Foundation, Inc.

Scientists Use MicroRNAs To Track Evolutionary History For First Time

ScienceDaily (Sep. 10, 2009) — The large group of segmented worms known as annelids, which includes earthworms, leeches and bristle worms, evolved millions of years ago and can be found in every corner of the world. Although annelids are one of the most abundant animal groups on the planet, scientists have struggled to understand how the different species of this biologically diverse group relate to each other in terms of their evolutionary history.

Now a team of scientists from Yale University and Dartmouth College has used a groundbreaking method to untangle some of that history.
The researchers used a novel source of data—the presence and absence of different microRNA genes—to investigate the evolutionary relationships of annelids. MicroRNAs are small, non-coding genes that have long been known to play an important role in developmental biology but which have never before been used to study the evolutionary relationships between organisms. The team’s findings appear online September 9 in the journal Proceedings of the Royal Society B.
“These genes are excellent evolutionary markers,” said lead author Erik Sperling, a graduate student in Yale’s Department of Geology and Geophysics. “Once a microRNA gene is fixed in a species, it is very rarely lost. As such, organisms with similar microRNAs are closely related to one another.”
Building on previous work done at Kevin Peterson’s lab at Dartmouth, which demonstrated the potential of using microRNAs to decipher evolutionary history, the team applied a form of high-throughput sequencing technology at the Yale Center for Genomics and Proteomics that uses a novel strategy to reveal the microRNA complement of an organism.
They discovered that certain groups of organisms previously shown by molecular analyses to lie within the annelid family, such as mollusks and peanut worms, could not have evolved from the same branch of the evolutionary tree as the rest of the annelids. Instead, the team’s results demonstrate that annelids represent a unique evolutionary branch separate from these other organisms. They also show that the ancestral annelid more closely resembled a kind of bristle worm that lived on the seafloor, as opposed to the classical belief that it was a kind of burrowing worm that lived in the ocean mud.
The team’s microRNA sequencing results also agree with the order in which the different annelids and their relatives appear in the fossil record—something that previous hypotheses about their relationships had failed to do, said co-author Derek Briggs, Yale’s Frederick William Beinecke Professor of Geology and Geophysics.
“This study is an elegant example of how new methods can reconcile results from molecular sequencing of living animals with information from the fossil record,” he said.
Authors of the paper include Erik Sperling, Jakob Vinther and Derek Briggs (Yale University), Vanessa Moy and Kevin Peterson (Dartmouth College), Benjamin Wheeler (North Carolina State University), and Marie Sémon (University of Lyon).

Bacteria Used To Make Radioactive Metals Inert

ScienceDaily (Sep. 9, 2009) — The Lost Orphan Mine below the Grand Canyon hasn't produced uranium since the 1960s, but radioactive residue still contaminates the area. Cleaning the region takes an expensive process that is only done in extreme cases, but Judy Wall, a biochemistry professor at the University of Missouri College of Agriculture, Food and Natural Resources, is researching the use of sulfate-reducing bacteria to convert toxic radioactive metal to inert substances, a much more economical solution.

The bacteria Wall is studying are bio-corrosives and can change the solubility of heavy metals. They can take uranium and convert it to uraninite, a nearly insoluble substance that will sink to the bottom of a lake or stream. Wall is looking into the bacteria's water cleansing ability and how long the changed material would remain inert.

Wall's research could also be beneficial to heavy metal pollution from storage tanks and industrial waste. The bacteria are already present in more than 7,000 heavy metal contaminated sites, but they live in a specific range of oxygen and temperature, making them difficult to control.

"Our research must be done in the absence of air," Wall said. "Obviously, none but the most committed – and stubborn – will work with them."

Even if an oxygen-tolerant strain were developed, there are still multiple factors that would make applying the bacteria challenging, and these microbes can contribute to massive iron corrosion.

"Knowledge of the way bacteria live in the environment, in microbial communities, is still in its infancy," Wall said. "We just don't know a lot about the communication systems among microbes."

Wall and researchers from the Lawrence Berkley National Laboratory in California are investigating the bacterium's basic genetics and hope to determine its growth limits and activity in natural settings, including how to make its interactions with metals sustainable. They have already identified a few genes that are critical to converting uranium.

Wall's research has been published in Applied and Environmental Microbiology, Nucleic Acids Research and Environmental Microbiology.

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