Science is the poetry of Nature.







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Posts tagged "biology"

I meet many people offended by evolution, who passionately prefer to be the personal handicraft of God than to arise by blind physical and chemical forces over aeons from slime…What they wish to be true, they believe is true.

Only 9 percent of Americans accept the central finding of modern biology that human beings (and all other species) have slowly evolved by natural processes from a succession of more ancient beings with no divine intervention needed along the way.

Carl Sagan (via whats-out-there)

(via afro-dominicano)

Colonies of Growing Bacteria Make Psychedelic Art

Images: 1) P. vortex exposed to a chemotherapy substance 2) P. vortex 3) Vortex Blue (P. vortex) 4) A close look at P. dendritiformis 5) Bacterial Dragon (Paenibacillus dendritiformis)

Israeli physicist Eshel Ben-Jacob uses bacteria as an art medium, shaping colonies in petri dishes into bold patterns

(via afro-dominicano)

skeptv:

The Million Women Study: Understanding Women’s Health

The most comprehensive study of women’s health in modern history has yielded some surprising results. Professor Dame Beral presents these findings and advises on healthcare and lifestyle.

The Million Women Study, a national study of women’s health in collaboration with Cancer Research UK and the National Health Service, aims to answer many outstanding questions about the factors affecting women’s health.

The transcript and downloadable versions of the lecture are available from the Gresham College Website: http://www.gresham.ac.uk/lectures-and-events/the-million-women-study

Duration: 56:50

via Gresham College.


humanoidhistory:

Happy birthday to trailblazing scientist Barbara McClintock (June 16, 1902-September 2, 1992). One of the world’s most distinguished cytogeneticists, she is best known for her discovery of DNA transposition, the moving of genetic material from one part of a chromosome to another. Basically, she helped to prove genes were not static and unchanging as they passed from one generation to another. McClintock won 1983 Nobel Prize in Physiology or Medicine for “her discovery of mobile genetic elements.” Here’s the bulk of her speech at the Nobel Banquet in Sweden on December 10, 1983:

"I understand I am here this evening because the maize plant, with which I have worked for many years, revealed a genetic phenomenon that was totally at odds with the dogma of the times, the mid-nineteen forties. Recently, with the general acceptance of this phenomenon, I have been asked, notably by young investigators, just how I felt during the long period when my work was ignored, dismissed, or aroused frustration. At first, I must admit, I was surprised and then puzzled, as I thought the evidence and the logic sustaining my interpretation of it, were sufficiently revealing. It soon became clear, however, that tacit assumptions - the substance of dogma - served as a barrier to effective communication. My understanding of the phenomenon responsible for rapid changes in gene action, including variegated expressions commonly seen in both plants and animals, was much too radical for the time. A person would need to have my experiences, or ones similar to them, to penetrate this barrier. Subsequently, several maize geneticists did recognize and explore the nature of this phenomenon, and they must have felt the same exclusions. New techniques made it possible to realize that the phenomenon was universal, but this was many years later. In the interim I was not invited to give lectures or seminars, except on rare occasions, or to serve on committees or panels, or to perform other scientists’ duties. Instead of causing personal difficulties, this long interval proved to be a delight. It allowed complete freedom to continue investigations without interruption, and for the pure joy they provided."

(NobelPrize.org/U.S. National Library of Medicine)

for-science-sake:

  • Lone Star Tick Mouth
  • Neurons in the Cerebellum 
  • Yeast Cells 
  • HIV Cells 
  • Hairs on a Gecko
  • Angel Fish Ovary

Source

(via afro-dominicano)

Everything is the way it is because it got that way.
Biologist and extremely-British-name-having D’Arcy Wentworth Thompson (1860-1948), succinctly summing up evolution in one sentence. (via jtotheizzoe)

sciencesoup:

Prokaryotes vs Eukaryotes

We know how to tell if something is alive or not, but if a bacterium and a dog are both living organisms, then what differentiates them? There are actually two distinct types of living beings, prokaryotes and eukaryotes, each made up of specialised prokaryotic and eukaryotic cells. In the three phylums of life—bacteria, archaea, and eukarya—prokaryotes cover the first two, and eukaryotes cover eukarya. You can probably already guess which groups a bacterium and a dog belong to, but let’s find out why.

All cells (i.e., both prokaryotes and eukaryotes) contain four common structures:

  1. A plasma membrane, which is a “barrier” that separates the cell from the outside world, like how your skin prevents your organs from falling out.
  2. The cytoplasm, which is the jelly-like substance that takes up the spaces inside the cell that aren’t already occupied by organelles.
  3. Nucleic acids, the genetic material, which tell the cell how to operate and reproduce.
  4. Ribosomes, where protein synthesis takes place according to the information contained in the genetic material. Proteins are organic compounds essential to living organisms, and they’ll be explored in more detail in a later article.

But there are also fundamental differences between living cells. Prokaryotic organisms as a whole are much smaller than eukaryotes, because they’re just made up of single cells, while eukaryotic organisms are made up of many specialised cells. The size of individual cells is different, too: prokaryotes are about 1-10 µm (micrometres) in diameter, while eukaryotes are 10-100 µm. If you want to get your head around the scale of things, go nuts with this interactive page.

Prokaryotes also lack a nuclear compartment and other membrane-bound organelles (which are like little organs within cells, each performing specific functions), so their genetic material and basic functioning processes happen out in the open, in the cytoplasm. This allows for less specialisation, so prokaryotes turn out to be pretty simple cells.

(Image source)

They reproduce asexually by binary fission, meaning that each cell splits in two to create a copy of itself. This gives rise to less diversity, but there is some scope for something called “horizontal gene exchange”: directly exchanging genetic information between the same generation, as opposed to passing genetic information onto the next generation. See illicit bacterial sex tape here.

Eukaryotes, on the other hand, have a range of organelles designed to perform specialised functions, such as the mitochondria, which creates the cell’s energy, the chloroplast, which converts light energy to chemical energy in plants, and the Golgi body, which modifies and processes proteins. This “compartmentalisation” allows for greater complexity—different compartments can have different functions even if they conflict, because they’re sealed off from each other.

Eukaryotes divide and reproduce by mitosis (the division of cells for tissue growth) and meiosis (the division of sex cells), and what results is two parents passing their genetic information onto the next generation. This creates the opportunity for more diversity, though it’s a longer process—some prokaryotes can divide and create a new organism in 20 minutes flat, while in humans it’s just a tad longer than that.

So what’s the difference between a bacterium and a dog? You can probably answer that yourself: bacteria are prokaryotic organisms and dogs are eukaryotic.

Further resources: Comparison table and Khan Academy video

science-junkie:

Proteins ‘ring like bells’

As far back as 1948, Erwin Schrödinger—the inventor of modern quantum mechanics—published the book “What is life?”

In it, he suggested that quantum mechanics and coherent ringing might be at the basis of all biochemical reactions. At the time, this idea never found wide acceptance because it was generally assumed that vibrations in protein molecules would be too rapidly damped.

Now, scientists at the University of Glasgow have proven he was on the right track after all. Using modern laser spectroscopy, the scientists have been able to measure the vibrational spectrum of the enzyme lysozyme, a protein that fights off bacteria. They discovered that this enzyme rings like a bell with a frequency of a few terahertz or a million-million hertz. Most remarkably, the ringing involves the entire protein, meaning the ringing motion could be responsible for the transfer of energy across proteins.

The experiments show that the ringing motion lasts for only a picosecond or one millionth of a millionth of a second. Biochemical reactions take place on a picosecond timescale and the scientists believe that evolution has optimised enzymes to ring for just the right amount of time. Any shorter, and biochemical reactions would become inefficient as energy is drained from the system too quickly. Any longer and the enzyme would simple oscillate forever: react, unreact, react, unreact, etc. The picosecond ringing time is just perfect for the most efficient reaction.

These tiny motions enable proteins to morph quickly so they can readily bind with other molecules, a process that is necessary for life to perform critical biological functions like absorbing oxygen and repairing cells. The findings have been published in Nature Communications.

Source: gla.ac.uk
Image: [x]

laboratoryequipment:

Museum Displays Cell Based, 3-D Printed Replica of van Gogh’s Ear

A German museum is displaying a copy of Vincent van Gogh’s ear that was grown using genetic material provided by one of the 19th century Dutch artist’s living relatives.

The Center for Art and Media in Karlsruhe says artist Diemut Strebe made the replica using living cells from Lieuwe van Gogh, the great-great-grandson of Vincent’s brother Theo. Using a 3-D printer, the cells were shaped to resemble the ear that Vincent van Gogh is said to have cut off during a psychotic episode in 1888.

Read more: http://www.laboratoryequipment.com/news/2014/06/museum-displays-cell-based-3-d-printed-replica-van-goghs-ear

(via afro-dominicano)

sciencesoup:

What is life?

This is the first article in an introductory biology series I’ll be writing over the next 4-6 weeks, starting from scratch and covering approximately final year high school/first semester university biology. My revision has begun, so buckle up: your learning is about to begin too.

The question of what is life? is as simple as it’s going to get, but also the most complex. Life is a weird, multi-faceted, conditional thing, and sometimes it’s hard to draw a line between what’s alive and what’s not. If I showed you a diamond, a virus, a fungus, a volcano, a dog, and a bacterium, how would you know which ones are living organisms?

There are a few key components of life, usually abbreviated to the acronym HOMER:

  1. Homeostasis: This is the regulation of internal conditions, like keeping pH and temperature constant. Polar bears, for example, help regulate their internal temperature with their thick coats.
  2. Organisation: Living things are built from complex assemblage of molecules, the smallest units of which are called cells.
  3. Metabolism: This is the transformation of energy for an organism’s use—for example, humans convert chemical energy from our food into energy that our cells can use to perform vital functions.
  4. Evolution: This is technically optional, because some living organisms don’t really evolve, but most are able to slowly change the genetic information passed down over generations, giving rise to diversity.
  5. Reproduction: Living organisms are able to pass on hereditary information into offspring.

Thinking about these five properties, let’s reconsider the list. A diamond and a volcano don’t tick any of our boxes and so are definitely not alive. A dog and a fungus are definitely alive. But the last two are more difficult to consider. What’s the difference between a bacterium and a virus? Well, we have to know a little bit more about them. Viruses are so harmful because they function by injecting their genetic material into a host, taking over the reproductive system in order to make more copes of themselves. They therefore don’t have their own reproductive system, since they have to hijack someone else’s—so they’re not alive.

Bacteria, on the other hand, tick all our boxes. We’ll find out a little more about them in the next article.

Further resources:First Life"  - David Attenborough documentary

currentsinbiology:

More than two-thirds of healthy Americans are infected with human papilloma viruses

In what is believed to be the largest and most detailed genetic analysis of its kind, researchers at NYU Langone Medical Center and elsewhere have concluded that 69 percent of healthy American adults are infected with one or more of 109 strains of human papillomavirus (HPV). Only four of the 103 men and women whose tissue DNA was publicly available through a government database had either of the two HPV types known to cause most cases of cervical cancer, some throat cancers, and genital warts.

Researchers say that while most of the viral strains so far appear to be harmless and can remain dormant for years, their overwhelming presence suggests a delicate balancing act for HPV infection in the body, in which many viral strains keep each other in check, preventing other strains from spreading out of control. Although infection is increasingly known to happen through skin-to-skin contact, HPV remains the most common sexually transmitted infection in the United States. It is so common that experts estimate nearly all men and women contract some strain of it during their lives.

Researchers at NYU Langone found 109 strains of HPV infection in tissue samples from the skin, vagina, mouth and gut of “healthy” American adults. Credit: Yingfei Ma, PhD, for NYU Langone

s-c-i-guy:

Mouse kidney

Mouse kidney section stained with Alexa Fluor 488 wheat germ agglutinin, Alexa Fluor 568 phalloidin and DAPI.

Image courtesy of Dr. Muthugapatti Kandasamy, Director of the Biomedical Microscopy Core. University of Georgia

source

(via afro-dominicano)

s-c-i-guy:

Researchers discover how DHA omega-3 fatty acid reaches the brain

It is widely believed that DHA (docosahexaenoic acid) is good for your brain, but how it is absorbed by the brain has been unknown. That is - until now. Researchers from Duke-NUS Graduate Medical School Singapore (Duke-NUS) have conducted a new study identifying that the transporter protein Mfsd2a carries DHA to the brain. Their findings have widespread implications for how DHA functions in human nutrition.

People know that DHA is an essential dietary nutrient that they can get from seafood and marine oils. Baby formula companies are especially attuned to the benefits of DHA, with nary a baby formula marketed without it.

DHA is an omega-3 fatty acid most abundantly found in the brain that is thought to be crucial to its function. However, the brain does not produce DHA. Instead, DHA uptake in the brain happens in two ways. The developing brain receives DHA during , from a mother to her baby. The adult brain gets it through food or DHA produced by the liver.

Though DHA is postulated to benefit the brain, the mechanics of how the brain absorbs the fatty acid has remained elusive. Senior author of the research, Associate Professor David L. Silver of Duke-NUS explained the importance of unlocking this mystery.

"If we could show the link by determining how DHA gets into the brain, then we could use this information to more effectively target its absorption and formulate an improved nutritional agent."

In the study, led by post-doctoral fellow Long N. Nguyen of Duke-NUS, researchers found that mice without the Mfsd2a transporter had brains a third smaller than those with the transporter, and exhibited memory and learning deficits and high levels of anxiety. The team recognized that the learning, memory and behavioral function of these mice were reminiscent of  deficiency in mice starved of DHA in their diet.

Image: Omega-3 fatty acid DHA transporter protein Mfsd2a is shown here as red fluorescence along mouse brain capillaries.

Image Credit: Long N. Nguyen

continue reading

(via afro-dominicano)