Posts tagged animals
Articles and news from the latest research reports.
Ion selectivity in neuronal signaling channels evolved twice in animals
July 26, 2012
Excitation of neurons depends on the selected influx of certain ions, namely sodium, calcium and potassium through specific channels. Obviously, these channels were crucial for the evolution of nervous systems in animals. How such channels could have evolved their selectivity has been a puzzle until now. Yehu Moran and Ulrich Technau from the University of Vienna together with Scientists from Tel Aviv University and the Woods Hole Oceanographic Institution (USA) have now revealed that voltage-gated sodium channels, which are responsible for neuronal signaling in the nerves of animals, evolved twice in higher and lower animals. These results were published in Cell Reports.
Close-up of nervous system of a transgenic polyp of the sea anemone Nematostella vectensis, in which a red fluorescent reporter gene (mCherry) is driven by the regulatory sequence of the neuronal ELAV gene. The picture shows the diffuse structure of the nervous system, but also reveals the accumulation of longitudinal axonal tracts along the eight gastric tissue folds (mesenteries). Credit: Copyright: U. Technau
The opening and closing of ion channels enable flow of ions that constitute the electrical signaling in all nervous systems. Every thought we have or every move we make is the result of the highly accurate opening and closing of numerous ion channels. Whereas the channels of most lower animals and their unicellular relatives cannot discern between sodium and calcium ions, those of higher animals are highly specific for sodium, a characteristic that is important for fast and accurate signaling in complex nervous system.
Surprising results in sea anemones and jellyfish
However, the researchers found that a group of basal animals with simple nerve nets including sea anemones and jellyfish also possess voltage-gated sodium channels, which differ from those found in higher animals, yet show the same selectivity for sodium. Since cnidarians separated from the rest of the animals more than 600 million years ago, these findings suggest that the channels of both cnidarians and higher animals originated independently twice, from ancient non-selective channels which also transmit calcium.
Since many other processes of internal cell signaling are highly dependent on calcium ions, the use of non-selective ion channels in neurons would accidently trigger various signaling systems inside the cells and will cause damage. The evolution of selectivity for sodium ions is therefore considered as an important step in the evolution of nervous systems with fast transmission. This study shows that different parts of the channel changed in a convergent manner during the evolution of cnidarians and higher animals in order to perform the same task, namely to select for sodium ions.
This demonstrates that important components for the functional nervous systems evolved twice in basal and higher animals, which suggests that more complex nervous systems that rely on such ion-selective channels could have also evolved twice independently.
Source: PHYS.ORG
Sheep backpacks reveal flocking strategy
UK researchers have shown for the first time that instead of fleeing randomly when faced with danger, sheep head straight for the center of the flock.
Understanding this behavior in healthy animals may help researchers understand the breakdown in social behaviours caused by neurological disorders in sheep, as well as those in humans, such as Huntington’s disease.
The findings support a 40-year-old idea put forward by evolutionary biologist Bill Hamilton. He suggested that creatures as different as insects, fish and cattle all react to danger by moving towards the middle of their respective swarms, schools or herds. “Scientists agree that flocking behavior has evolved in response to the risk of being attacked by predators.
The idea is that being part of a tight-knit group not only increases the chances that you might spot a predator, but decreases the chance that you are the one the predator goes for when it attacks,” explains Dr. Andrew King from The Royal Veterinary College (RVC), lead author the study, published in Current Biology today.
Aesop’s Fable Unlocks How Crows and Kids Think
Scientists have used an age-old fable to help illustrate how we think differently to other animals.
Lucy Cheke, a PhD student at the University of Cambridge’s Department of Experimental Psychology, expanded Aesop’s fable into three tasks of varying complexity and compared the performance of Eurasian Jays with local school children.
The task that set the children apart from the Jays involved a mechanism which was counter-intuitive as it was hidden under an opaque surface. Neither the birds nor the children were able to learn how the mechanism worked, but the children were able to learn how to get the reward, whereas the birds were not.
The results of the study illustrate that children learn about cause and effect in the physical world in a different way to birds. While the Jay’s appear to take account of the mechanism involved in the task, the children are more driven by simple cause-effect relationships.
In the insect brain, dopamine-releasing nerve cells are crucial to the formation of both punished and rewarded memories.
Hiromu Tanimoto and his colleagues at the Max Planck Institute of Neurobiology recently localised and identified the most important types of nerve cells involved in forming positive and negative memories of a fruit fly. All four nerve cell types they discovered use dopamine to communicate with other nerve cells. The dopamine signals released by these cells are received in the mushroom body, a prominent brain structure in insect brains. “It is really surprising that similar dopamine-releasing nerve cells can play such different roles,” says Tanimoto.
Read more: Dopamine – A substance with many messages
On the fifth day of the fifth month of 1921, Coco Chanel changed the scent of the world. She released Chanel No. 5as her final vaudeville act—her only child. The perfume would grow to be “le monstre"of the perfume industry, a $300-per-ounce, elegant mist still anchoring the multibillion-dollar Chanel empire. It succeeded where others had never tried by combining the cheap, musky scent of the courtesan demi-mondaines—the “women of the half-world,” as Coco herself was—with the light, single florals reserved for the upper class of Parisian women. Needing a musky base note, Coco resorted to an old perfumer’s trick: scrapings of sexual pheromones from the perianal gland of the Abyssinian civet cat.
Why is it that the elite French perfumers (known as “noses”) and sommeliers (“upturned noses”) of the world spend so much of their time inhaling cat effluvia from expensive glass bottles? A guess: It may have to do with a mind-control parasite called Toxoplasma gondii.
Read more: The Scent of a Cat Woman: Is the secret to Chanel No. 5’s success a parasite?
Bees Can ‘Turn Back Time,’ Reverse Brain Aging
ScienceDaily (July 3, 2012) — Scientists at Arizona State University have discovered that older honey bees effectively reverse brain aging when they take on nest responsibilities typically handled by much younger bees. While current research on human age-related dementia focuses on potential new drug treatments, researchers say these findings suggest that social interventions may be used to slow or treat age-related dementia.
Old bees collect nectar and pollen. Most bees start doing this job when they are 3-4 weeks old, and after that they age very quickly. Their bodies and wings become worn and they loose the ability to learn new things. Most food collector bees die after about 10 days. (Credit: Christofer Bang)
In a study published in the scientific journal Experimental Gerontology, a team of scientists from ASU and the Norwegian University of Life Sciences, led by Gro Amdam, an associate professor in ASU’s School of Life Sciences, presented findings that show that tricking older, foraging bees into doing social tasks inside the nest causes changes in the molecular structure of their brains.
"We knew from previous research that when bees stay in the nest and take care of larvae — the bee babies — they remain mentally competent for as long as we observe them," said Amdam. "However, after a period of nursing, bees fly out gathering food and begin aging very quickly. After just two weeks, foraging bees have worn wings, hairless bodies, and more importantly, lose brain function — basically measured as the ability to learn new things. We wanted to find out if there was plasticity in this aging pattern so we asked the question, ‘What would happen if we asked the foraging bees to take care of larval babies again?"
During experiments, scientists removed all of the younger nurse bees from the nest — leaving only the queen and babies. When the older, foraging bees returned to the nest, activity diminished for several days. Then, some of the old bees returned to searching for food, while others cared for the nest and larvae. Researchers discovered that after 10 days, about 50 percent of the older bees caring for the nest and larvae had significantly improved their ability to learn new things.
Amdam’s international team not only saw a recovery in the bees’ ability to learn, they discovered a change in proteins in the bees’ brains. When comparing the brains of the bees that improved relative to those that did not, two proteins noticeably changed. They found Prx6, a protein also found in humans that can help protect against dementia — including diseases such as Alzheimer’s — and they discovered a second and documented “chaperone” protein that protects other proteins from being damaged when brain or other tissues are exposed to cell-level stress.
In general, researchers are interested in creating a drug that could help people maintain brain function, yet they may be facing up to 30 years of basic research and trials.
"Maybe social interventions — changing how you deal with your surroundings — is something we can do today to help our brains stay younger," said Amdam. "Since the proteins being researched in people are the same proteins bees have, these proteins may be able to spontaneously respond to specific social experiences."
Amdam suggests further studies are needed on mammals such as rats in order investigate whether the same molecular changes that the bees experience might be socially inducible in people.
Source: Science Daily
DNA Sequenced for Parrot’s Ability to Parrot
July 2nd, 2012
Third-generation sequencing debugged to glimpse parrots’ ability to imitate.
Scientists say they have assembled more completely the string of genetic letters that could control how well parrots learn to imitate their owners and other sounds.
The research team unraveled the specific regions of the parrots’ genome using a new technology, single molecule sequencing, and fixing its flaws with data from older DNA-decoding devices. The team also decoded hard-to-sequence genetic material from corn and bacteria as proof of their new sequencing approach.
The results of the study appeared online July 1 in the journal Nature Biotechnology.
Single molecule sequencing “got a lot of hype last year” because it generates long sequencing reads, “supposedly making it easier to assemble complex parts of the genome,” said Duke University neurobiologist Erich Jarvis, a co-author of the study.
He is interested in the sequences that regulate parrots’ imitation abilities because they could give neuroscientists information about the gene regions that control speech development in humans.
This male budgie from the Fort Worth Zoo is like the parrots Erich Jarvis uses to study vocal learning behaviors, but probably without the text bubble. Image adapted from an image credited to Jerry Tillery via Wikimedia Commons. More info in notes below.
Jarvis began his project with collaborators by trying to piece together the genome regions with what are known as next-generation sequencers, which read chunks of 100 to 400 DNA base pairs at a time and then take a few days to assemble them into a draft genome. After doing the sequencing, the scientists discovered that the read lengths were not long enough to assemble the regulatory regions of some of the genes that control brain circuits for vocal learning.
University of Maryland computational biologists Adam Phillippy and Sergey Koren — experts at assembling genomes — heard about Jarvis’s sequencing struggles at a conference and approached him with a possible solution of modifying the algorithms that order the DNA base pairs. But the fix was still not sufficient.
Last year, 1000 base-pair reads by Roch 454 became available, as did the single molecule sequencer by Pacific Biosciences. The Pacbio technology generates strands of 2,250 to 23,000 base pairs at a time and can draft an entire genome in about a day.
Jarvis and others thought the new technologies would solve the genome-sequencing challenges. Through a competition, called the Assemblathon, the scientists discovered that the Pacbio machine had trouble accurately decoding complex regions of the parrot, Melopsittacus undulates, genome. The machine had a high error rate, generating the wrong genetic letter at every fifth or sixth spot in a string of DNA. The mistakes made it nearly impossible to create a genome assembly with the very long reads, Jarvis said.
But with a team, including scientists from the DOE Genome Science Institute and Cold Spring Harbor in New York, Phillippy, Koren and Jarvis corrected the Pacbio sequencer’s errors using shorter, more accurate codes from the next-generation devices. The fix reduces the single-molecule, or third-generation, sequencing machine’s error rate from 15 percent to less than one-tenth of one percent.
“Finally we have been able to assemble the regulatory regions of genes, such as FoxP2 and egr1, that are of interest to us and others in vocal learning behavior,” Jarvis said.
He explained that FoxP2 is a gene required for speech development in humans and vocal learning in birds that learn to imitate sounds, like songbirds and parrots. Erg1 is a gene that controls the brain’s ability to reorganize itself based on new experiences.
By being able to decode and organize the DNA that regulates these regions, neuroscientists may be able to better understand what genetic mechanism causes birds to imitate and sing well. They may also be able to collect more information about genetic factors that affect a person’s ability to learn how to communicate well and to speak, Jarvis said. He and his team plan to describe the biology of the parrotâs genetic code they sequenced in more detail in an upcoming paper.
Jarvis added that as more scientists use the hybrid sequencing approach, they could possibly decode complex, elusive genes linked to how cancer cells develop and to the sequences that control other brain functions.
Source: Neuroscience News
What was he thinking? Study turns to ape intellect
June 24, 2012 by SETH BORENSTEIN
(AP) — The more we study animals, the less special we seem.
In this Dec. 13, 2006 photo provided by the Primate Research Institute of Kyoto University, a 5 1/2-year-old chimpanzee named Ayumu performs a memory test with randomly-placed consecutive Arabic numerals, which are later masked, accurately duplicating the lineup on a touch screen computer in Kyoto, Japan. The young chimpanzees in the study titled “Working memory of numerals in chimpanzees” by Sana Inoue and Tetsuro Matsuzawa could memorize the nine numerals much faster and more accurately than human adults. The evidence that animals are more intelligent and more social than we thought seems to grow each year, especially when it comes to primates. It’s an increasingly hot scientific field with the number of ape and monkey cognition studies doubling in recent years, often with better technology and neuroscience paving the way to unusual discoveries. (AP Photo/Primate Research Institute of Kyoto University) PART OF A SEVEN-PICTURE PACKAGE WITH “ANIMAL SCIENCES”
Baboons can distinguish between written words and gibberish. Monkeys seem to be able to do multiplication. Apes can delay instant gratification longer than a human child can. They plan ahead. They make war and peace. They show empathy. They share.
"It’s not a question of whether they think — it’s how they think," says Duke University scientist Brian Hare. Now scientists wonder if apes are capable of thinking about what other apes are thinking.
The evidence that animals are more intelligent and more social than we thought seems to grow each year, especially when it comes to primates. It’s an increasingly hot scientific field with the number of ape and monkey cognition studies doubling in recent years, often with better technology and neuroscience paving the way to unusual discoveries.
Extensive Taste Loss in Mammals
March 12th, 2012
Scientists from the Monell Center report that seven of 12 related mammalian species have lost the sense of sweet taste. As each of the sweet-blind species eats only meat, the findings demonstrate that a liking for sweets is frequently lost during the evolution of diet specialization.
Previous research from the Monell team had revealed the remarkable finding that both domestic and wild cats are unable to taste sweet compounds due to defects in a gene that controls structure of the sweet taste receptor.
Cats are obligate carnivores, meaning that they subsist only on meat. In the current study, published online in Proceedings of the National Academy of Sciences USA, the Monell scientists next asked whether other strict carnivores have also lost the sweet taste receptor.
To do this, they examined sweet taste receptor genes from 12 related mammalian species with varying dietary habits. They once again found taste loss and to their surprise, it was widespread in the meat-eating species.
Senior author Gary Beauchamp, Ph.D., a behavioral biologist at Monell, comments, “Sweet taste was thought to be nearly a universal trait in animals. That evolution has independently led to its loss in so many different species was quite unexpected.”