How do marine mammals avoid the bends?

Deep-diving whales and other marine mammals can get the bends -- the same painful and potentially life-threatening decompression sickness that strikes scuba divers who surface too quickly. A new study offers a hypothesis of how marine mammals generally avoid getting the bends and how they can succumb under stressful conditions, according to Science Daily.

The key is the unusual lung architecture of whales, dolphins and porpoises (and possibly other breath-holding diving vertebrates), which creates two different pulmonary regions under deep-sea pressure, say researchers.

"How some marine mammals and turtles can repeatedly dive as deep and as long as they do has perplexed scientists for a very long time," says Michael Moore, co-author of the study. "This paper opens a window through which we can take a new perspective on the question."

When air-breathing mammals dive to high-pressure depths, their lungs compress. That collapses their alveoli -- the tiny sacs at the end of the airways where gas exchange occurs. Nitrogen bubbles build up in the animals' bloodstream and tissue. If they ascend slowly, the nitrogen can return to the lungs and be exhaled. But if they ascend too fast, the nitrogen bubbles don't have time to diffuse back into the lungs. Under less pressure at shallower depths, the nitrogen bubbles expand in the bloodstream and tissue, causing pain and damage.

Marine mammals' chest structure allows their lungs to compress. Scientists have assumed that this passive compression was marine mammals' main adaptation to avoid taking up excessive nitrogen at depth and getting the bends.

The heartbeat of a tree: Scientists discover plants pulsate throughout the night

It might seem as though trees spend most of their lives standing still – but, according to new research, they do a lot more moving than you’d think, according to Daily Mail.

Scientists have discovered the subtle ‘heartbeat’ of trees and shrubs, using terrestrial laser scanning to measure the overnight movement of branches and leaves.

While only some trees in the study were shown to follow a ‘sleep cycle,’ in which their branches lowered at night and returned to their daytime position hours later, the researchers found that all of the trees displayed minute, periodic pulses.

The discovery suggests trees are pumping water, the experts say. 

New ancestor of modern sea turtles found

A sea turtle discovered is a new species from the Late Cretaceous epoch, according to a Science Daily.

Modern day sea turtles were previously thought to have had a single ancestor of the of the Peritresius clade during the Late Cretaceous epoch, from about 100 to 66 million years ago. This ancestral species, Peritresius ornatus, lived exclusively in North America, but few Peritresius fossils from this epoch had been found, an area known for producing large numbers of Late Cretaceous marine turtle fossils. In this study, the research team analyzed sea turtle fossils collected from marine sediments, dating from about 83 to 66 million years ago.

Marine fish won an evolutionary lottery 66 million years ago

Why do our oceans contain such a staggering diversity of fish of so many different sizes, shapes and colors? A team of biologists reports that the answer dates back 66 million years, when a six-mile-wide asteroid crashed to Earth, wiping out the dinosaurs and approximately 75 percent of the world's animal and plant species, according to Science Daily.

Slightly more than half of today's fish are "marine fish," meaning they live in oceans. And most marine fish, including tuna, halibut, grouper, sea horses and mahi-mahi, belong to an extraordinarily diverse group called acanthomorphs.

How life generates new forms

When organisms change during the course of evolution, often what drives new forms is not genes themselves, but gene regulation -- what turns genes on and off. A new study identifies the kind of gene regulation most likely to generate evolutionary change, according to Science Daily.

Most modern organisms store genetic information in DNA and transcribe the information from DNA into RNA. Protein "transcription factors" that inhibit or enhance transcription of genes in the DNA are said to regulate gene expression.

In a March paper, a team demonstrated that gene regulation by protein transcription factors more readily powers evolutionary change than another form of gene regulation that works at the RNA level.