Tag Archives: Life Science

Roger Tsien Lecture On Green Florescent Protein

Nobel Laureate Roger Tsien discusses his research on green florescent protein. From the Nobel Prize web site:

n the 1960s, when the Japanese scientist Osamu Shimomura began to study the bioluminescent jelly-fish Aequorea victoria, he had no idea what a scientific revolution it would lead to. Thirty years later, Martin Chalfie used the jellyfish’s green fluorescent protein to help him study life’s smallest building block, the cell.
…
when Anton van Leeuwenhoek invented the microscope in the 17th century a new world opened up. Scientists could suddenly see bacteria, sperm and blood cells. Things they previously did not know even existed. This year’s Nobel Prize in Chemistry rewards a similar effect on science. The green fluorescent protein, GFP, has functioned in the past decade as a guiding star for biochemists, biologists, medical scientists and other researchers.
…
This is where the third Nobel Prize laureate Roger Tsien makes his entry. His greatest contribution to the GFP revolution was that he extended the researchers’ palette with many new colours that glowed longer and with higher intensity.

To begin with, Tsien charted how the GFP chromophore is formed chemically in the 238-amino-acid-long GFP protein. Researchers had previously shown that three amino acids in position 65–67 react chemically with each other to form the chromosphore. Tsien showed that this chemical reaction requires oxygen and explained how it can happen without the help of other proteins.

With the aid of DNA technology, Tsien took the next step and exchanged various amino acids in different parts of GFP. This led to the protein both absorbing and emitting light in other parts of the spectrum. By experimenting with the amino acid composition, Tsien was able to develop new variants of GFP that shine more strongly and in quite different colours such as cyan, blue and yellow. That is how researchers today can mark different proteins in different colours to see their interactions.

The Calorie Delusion

The calorie delusion: Why food labels are wrong

Nutritionists are well aware that our bodies don’t incinerate food, they digest it. And digestion – from chewing food to moving it through the gut and chemically breaking it down along the way – takes a different amount of energy for different foods. According to Geoffrey Livesey, an independent nutritionist based in Norfolk, UK, this can lower the number of calories your body extracts from a meal by anywhere between 5 and 25 per cent depending on the food eaten.
…
Dietary fibre is one example. As well as being more resistant to mechanical and chemical digestion than other forms of carbohydrate, dietary fibre provides energy for gut microbes, and they take their cut before we get our share. Livesey has calculated that all these factors reduce the energy derived from dietary fibre by 25 per cent
…
“Cooking gives food energy,” says Wrangham. It alters the structure of the food at the molecular level, making it easier for our body to break it up and extract the nutrients.

In plants, for example, much of the energy from starch is stored as amylopectin, which is semi-crystalline, does not dissolve in water, and cannot be easily digested. Heat starchy foods with water, though, and the crystalline forms begin to melt. The starch granules absorb water, swell, and eventually burst. The amylopectin is shattered into short starch molecules called amylose, which are easily digested by the enzyme amylase.

It seems pretty obvious, just looking around, as you walk around in any city that people are much fatter, on average, than we were 20 years ago. And the data shows people were much larger (taller, but also fatter) 20 years ago than they were 100 years ago. And we know obesity causes many human health issues. The failure to address the obesity problem in the USA is another example of the failed “health care” system. Instead of a working health care system we just manage diseases that result for unhealthy living. We should be do better at providing information to people on healthy eating (including more accurate calorie counts as it concerns food we eat) and healthy lifestyle choices.

Pigeon Solves Box and Banana Problem

Laboratory footage showing a pigeon solving Wolfgang Kohler’s famous box-and-banana problem, which he studied with chimpanzees in the early 1900s. Depending on their previous experience, pigeons could solve this problem in a human-like fashion in as little as a minute. This pigeon has learned to push boxes and to climb, and it has been rewarded with grain for pecking at a small toy banana.

In this situation, the banana is out of reach and the box is not beneath it. At first the pigeon looks confused, then it begins pushing the box – sighting the toy banana as it pushes – and then stops pushing when the box is beneath the banana, then climbs and pecks. This and related studies were summarized in Dr. Epstein‘s 1996 book, Cognition, Creativity, & Behavior.

This is another example of interesting thoughtful bird behavior.

The Evolution of House Cats

Photo shows Fritz the Cat – see photos Fritz took.

Scientific American has a long and interesting article on: The Evolution of House Cats

It is by turns aloof and affectionate, serene and savage, endearing and exasperating. Despite its mercurial nature, however, the house cat is the most popular pet in the world. A third of American households have feline members, and more than 600 million cats live among humans worldwide.
…
Together the transport of cats to the island and the burial of the human with a cat indicate that people had a special, intentional relationship with cats nearly 10,000 years ago in the Middle East. This locale is consistent with the geographic origin we arrived at through our genetic analyses. It appears, then, that cats were being tamed just as humankind was establishing the first settlements in the part of the Middle East known as the Fertile Crescent.
…
Over time, wildcats more tolerant of living in human-dominated environments began to proliferate in villages throughout the Fertile Crescent. Selection in this new niche would have been principally for tameness, but competition among cats would also have continued to influence their evolution and limit how pliant they became. Because these proto–domestic cats were undoubtedly mostly left to fend for themselves, their hunting and scavenging skills remained sharp. Even today most domesticated cats are free agents that can easily survive independently of humans, as evinced by the plethora of feral cats in cities, towns and countrysides the world over.
…
So are today’s cats truly domesticated? Well, yes—but perhaps only just. Although they satisfy the criterion of tolerating people, most domestic cats are feral and do not rely on people to feed them or to find them mates. And whereas other domesticates, like dogs, look quite distinct from their wild ancestors, the average domestic cat largely retains the wild body plan. It does exhibit a few morphological differences, however—namely, slightly shorter legs, a smaller brain and, as Charles Darwin noted, a longer intestine, which may have been an adaptation to scavenging kitchen scraps.

Cats are Cool 🙂

Saving the World with Science and Mushrooms

Entrepreneurial mycologist Paul Stamets studies mushrooms. The focus of Stamets’ research is the Northwest’s native fungal genome, mycelium, but along the way he has filed 22 patents for mushroom-related technologies, including pesticidal fungi that trick insects into eating them, and mushrooms that can break down the neurotoxins used in nerve gas.

The webcast really gets interesting at minute 9 or so (in my opinion) with 6 specific examples.

Related: Fun Fungi – Thinking Slime Moulds – Microbe Types

Antigen Shift in Influenza Viruses

Antigenic shift is the process by which at least two different strains of a virus, (or different viruses), especially influenza, combine to form a new subtype having a mixture of the surface antigens of the two original strains.

Pigs can be infected with human, avian and swine influenza viruses. Because pigs are susceptible to all three they can be a breeding ground for antigenic shift (as in the recent case of H1N1 Flu – Swine Flu) allowing viruses to mix and create a new virus.

Continue reading →

Evolutionary Robotics

Evolutionary Robotics, chapter of Handbook of Robotics, is interesting and includes a good explanation of the difference between evolution and learning:

Evolution and learning (or phylogenetic and ontogenetic
adaptation) are two forms of biological adaptation that differ in space and time. Evolution is a process of selective reproduction and substitution based on the existence of a population of individuals displaying variability at the genetic level. Learning, instead, is a set of modifications taking place within each single individual during its own life time.

Evolution and learning operate on different time scales. Evolution is a form of adaptation capable of capturing relatively slow environmental changes that

might encompass several generations (e.g., the perceptual characteristics of food sources for a given species). Learning, instead, allows an individual to adapt to environmental modifications that are unpredictable at the generational level. Learning might include a variety of mechanisms that produce adaptive changes in an individual during its lifetime, such as physical development, neural maturation, variation of the connectivity between neurons, and synaptic plasticity. Finally, whereas evolution operates on the genotype, learning affects only the phenotype and phenotypic modifications cannot directly modify the genotype.
…
Recent research showed that teams of evolved robots can: (a) develop robust and effective behavior, (b) display an ability to differentiate their behavior so
to better cooperate; (c) develop communication capabilities and a shared communication system.

Iron-breathing Species Isolated in Antarctic for Millions of Years

Graphic showing environment of Antarctic subglacial microbes

Graphic of Blood Falls showing microbial community environment in the Antarctic by Zina Deretsky at NSF)

A reservoir of briny liquid buried deep beneath an Antarctic glacier supports hardy microbes that have lived in isolation for millions of years, researchers report this week. The discovery of life in a place where cold, darkness, and lack of oxygen would previously have led scientists to believe nothing could survive comes from a team led by researchers at Harvard University and Dartmouth College.

Despite their profound isolation, the microbes are remarkably similar to species found in modern marine environments, suggesting that the organisms now under the glacier are the remnants of a larger population that once occupied an open fjord or sea.

“It’s a bit like finding a forest that nobody has seen for 1.5 million years,” says Ann Pearson, Thomas D. Cabot Associate Professor of Earth and Planetary Sciences in Harvard’s Faculty of Arts and Sciences. “Intriguingly, the species living there are similar to contemporary organisms, and yet quite different — a result, no doubt, of having lived in such an inhospitable environment for so long.”

“This briny pond is a unique sort of time capsule from a period in Earth’s history,” says lead author Jill Mikucki, now a research associate in the Department of Earth Sciences at Dartmouth and visiting fellow at Dartmouth’s Dickey Center for International Understanding and its Institute of Arctic Studies. “I don’t know of any other environment quite like this on Earth.”

Chemical analysis of effluent from the inaccessible subglacial pool suggests that its inhabitants have eked out a living by breathing iron leached from bedrock with the help of a sulfur catalyst. Lacking any light to support photosynthesis, the microbes have presumably survived by feeding on the organic matter trapped with them when the massive Taylor Glacier sealed off their habitat an estimated 1.5 to 2 million years ago.
Continue reading →

Nanoparticles With Scorpion Venom Slow Cancer Spread

In a, chlorotoxin molecules, colored blue and green, attach themselves to a central nanoparticle. In b, each nanoprobe offers many chlorotoxin molecules that can simultaneously latch on to many MMP-2s, depicted here in yellow, which are thought to help tumor cells travel through the body. In c, over time nanoprobes draw more and more of the MMP-2 surface proteins into the cell, slowing the tumor’s spread. Image from the University of Washington.

University of Washington researchers found they could cut the spread of cancerous cells by 98 percent, compared to 45 percent for the scorpion venom alone, by combining nanoparticles with a scorpion venom compound already being investigated for treating brain cancer.

For more than a decade scientists have looked at using chlorotoxin, a small peptide isolated from scorpion venom, to target and treat cancer cells. Chlorotoxin binds to a surface protein overexpressed by many types of tumors, including brain cancer. Previous research by Miqin Zhang‘s group combined chlorotoxin with nanometer-scale particles of iron oxide, which fluoresce at that size, for both magnetic resonance and optical imaging.

Chlorotoxin also disrupts the spread of invasive tumors — specifically, it slows cell invasion, the ability of the cancerous cell to penetrate the protective matrix surrounding the cell and travel to a different area of the body to start a new cancer. The MMP-2 on the cell’s surface, which is the binding site for chlorotoxin, is hyperactive in highly invasive tumors such as brain cancer. Researchers believe MMP-2 helps the cancerous cell break through the protective matrix to invade new regions of the body. But when chlorotoxin binds to MMP-2, both get drawn into the cancerous cell.

Research showed that the cells containing nanoparticles plus chlorotoxin were unable to elongate, whereas cells containing only nanoparticles or only chlorotoxin could stretch out. This suggests that the nanoparticle-plus-chlorotoxin disabled the machinery on the cell’s surface that allows cells to change shape, yet another step required for a tumor cell to slip through the body.

So far most cancer research has combined nanoparticles either with chemotherapy that kills cancer cells, or therapy seeking to disrupt the genetic activity of a cancerous cell. This is the first time that nanoparticles have been combined with a therapy that physically stops cancer’s spread.

Full press release

Amazonian Ant Species is All Female, Reproduces By Cloning

Ants inhabit ‘world without sex’

The ants reproduce via cloning – the queen ants copy themselves to produce genetically identical daughters. This species – the first ever to be shown to reproduce entirely without sex – cultivates a garden of fungus, which also reproduces asexually.
…
Dr Himler’s interest in Mycocepurus smithii was originally sparked not by their unusually biased sex ratio, but by their ability to cultivate crops. “Ants discovered farming long before we did – they have been cultivating fungus gardens for an estimated 80 million years.

“They collect plant material, insect faeces and even dead insects from the forest floor and feed it to their crops,” she said.