genes

‘Two simple words in the English language: I forgot!’ –Steve Martin

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In December last year, researchers Brian Dias and Kerry Ressler made a splash with a paper seeming to show that memories can be inherited.

This article, published in Nature Neuroscience, reported that if adult mice are taught to be afraid of a particular smell, then their children will also fear it. Which is pretty wild. Epigenetics was proposed as the mechanism.

Now, however, psychologist Gregory Francis says that the data Dias and Ressler published are just too good to be true.

{ Neuroskeptic | Continue reading }

‘If I accede to Parmenides there is nothing left but the One; if I accede to Zeno, not even the One is left.’ –Seneca the Younger

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Memories may be passed down through generations in DNA in a process that may be the underlying cause of phobias.

{ Telegraph | Continue reading }

photo { Guy Sargent }

I ain’t got no money, I ain’t like those other guys you hang around

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{ DNA tests prove your close friends are probably distant relatives }

images { 1 | 2 }

Being 21 is expensive lol

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For all those brunettes wishing they were naturally blond, a small genetic change could have made all the difference. Scientists have found that replacing one of DNA’s four letters at a key spot in the genome shifts a particular gene’s activity and leads to fairer hair. Not only does the work provide a molecular basis for flaxen locks, but it also demonstrates how changes in segments of DNA that control genes, not just changes in genes themselves, are important to what an organism looks like. […]

Over the past 6 years, studies of genetic variation in thousands of people have linked at least eight DNA regions to blondness based on the fact that a certain DNA letter, or base, was found in people with that hair color but not in people with other hair colors. Some of those base changes, or single-nucleotide polymorphisms (SNPs), were in genes involved in the production of pigments, such as melanin. Mutations in these genes typically change skin and hair color. Other SNPs lay outside genes but could be part of the regulatory DNA that helps control the function of genes nearby. Changes in that regulatory DNA could result in hair color but not skin color change, or vice versa, because regulatory DNA can change gene activity in just certain parts of the body.

{ Science | Continue reading }

related { Smokers with gene defect have one in four chance of developing lung cancer }

Let’s follow that fire truck I think your house is burnin down

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The average person misplaces up to nine items a day, and one-third of respondents in a poll said they spend an average of 15 minutes each day searching for items—cellphones, keys and paperwork top the list, according to an online survey of 3,000 people published in 2012 by a British insurance company. […]

In a recent study, researchers in Germany found that the majority of people surveyed about forgetfulness and distraction had a variation in the so-called dopamine D2 receptor gene (DRD2), leading to a higher incidence of forgetfulness. According to the study, 75% of people carry a variation that makes them more prone to forgetfulness.

{ WSJ | Continue reading }

related { Processing new information during sleep compromises memory }

photo { Daniel Bejar, The Visual Topography of a Generation Gap (Brooklyn, NY, #1), 2011 }

[Woody finds Buzz dressed up as ‘Mrs. Nesbitt’ and in the company of two headless dolls]

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Now there is hope in the form of new genome-engineering tools, particularly one called CRISPR. This technology could allow researchers to perform microsurgery on genes, precisely and easily changing a DNA sequence at exact locations on a chromosome. Along with a technique called TALENs, invented several years ago, and a slightly older predecessor based on molecules called zinc finger nucleases, CRISPR could make gene therapies more broadly applicable, providing remedies for simple genetic disorders like sickle-cell anemia and eventually even leading to cures for more complex diseases involving multiple genes.

{ Technology Review | Continue reading }

Just remember, when you control the mail, you control… information

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Amoebas are puny, stupid blobs, so scientists were surprised to learn that they contain 200 times more DNA than Einstein did. Because amoebas are made of just one cell, researchers assumed they would be simpler than humans genetically. Plus, amoebas date back farther in time than humans, and simplicity is considered an attribute of primitive beings. It just didn’t make sense. […]

Before the advent of rapid, accurate, and inexpensive DNA sequencing technology in the early 2000s, biologists guessed that genes would provide more evidence for increasing complexity in evolution. Simple, early organisms would have fewer genes than complex ones, they predicted. […] Instead, their assumptions of increasing complexity began to fall apart. […]

Then molecular analyses did something else. They rearranged the order of branches on evolutionary trees. Biologists pushed aside trees based on how similar organisms looked to one another, and made new ones based on similarities in DNA and protein sequences. The results suggested that complex body parts evolved multiple times and had also been lost. One study found that winged stick insects evolved from wingless stick insects who had winged ancestors. […]

Perhaps the fact that people are stunned whenever organisms become simpler says more about how the human mind organizes the world than about evolutionary processes. People are more comfortable envisioning increasing complexity through time instead of reversals or stasis.

{ Nautilus | Continue reading }

design { Sam Winston }

Punk is dad

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We have identified a Y-chromosomal lineage with several unusual features. It was found in 16 populations throughout a large region of Asia, stretching from the Pacific to the Caspian Sea, and was present at high frequency: ~8% of the men in this region carry it, and it thus makes up ~0.5% of the world total. The pattern of variation within the lineage suggested that it originated in Mongolia ~1,000 years ago. Such a rapid spread cannot have occurred by chance; it must have been a result of selection. The lineage is carried by likely male-line descendants of Genghis Khan, and we therefore propose that it has spread by a novel form of social selection resulting from their behavior.

{ National Institutes of Health }

An international group of geneticists studying Y-chromosome data have found that nearly 8 percent of the men living in the region of the former Mongol empire carry y-chromosomes that are nearly identical. That translates to 0.5 percent of the male population in the world, or roughly 16 million descendants living today. […]

To have such a startling impact on a population required a special set of circumstances, all of which are met by Genghis Khan and his male relatives, the authors note in the study.

[Genghis Khan lived from 1162-1227 and raped and pillaged from Mongolia to the gates of Vienna. Once he captured a village or town, he would essentially kill all the men and rape the women.]

The Y-chromosome is passed on as a chunk of DNA from father to son, basically unchanged through generations except for random mutations.

These random mutations, which happen naturally and are usually harmless, are called markers. Once the markers have been identified, geneticists can go back in time and trace them to the point at which they first occurred, defining a unique lineage of descent.

In this particular instance, the lineage originated 1,000 years ago. The authors aren’t saying that the genetic mutations defining the lineage originated with Khan, who was born around 1162; they are more likely to have been passed on to him by a great great grandfather.

[…]

The connection to Genghis Khan will never be a certainty unless his grave is found and his DNA could be extracted.

{ National Geographic | Continue reading | Audio: Radio Lab, Genghis Khan Episode }

The location of the tomb of Genghis Khan has been the object of much speculation and research. The site remains undiscovered. […] According to one legend, the funeral escort killed anyone and anything that crossed their path, in order to conceal where he was finally buried. After the tomb was completed, the slaves who built it were massacred, and then the soldiers who killed them were also killed.

{ Wikipedia | Continue reading }

Dusk and the light behind her

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Everyone grows older, but scientists don’t really understand why. Now a UCLA study has uncovered a biological clock embedded in our genomes that may shed light on why our bodies age and how we can slow the process. […]

While earlier clocks have been linked to saliva, hormones and telomeres, the new research is the first to identify an internal timepiece able to accurately gauge the age of diverse human organs, tissues and cell types. Unexpectedly, the clock also found that some parts of the anatomy, like a woman’s breast tissue, age faster than the rest of the body.

{ EurekAlert | Continue reading }

photo { Ray Metzker }

Like the chocolate of Vavey, in the sun they’ll melt away

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From biology class to “C.S.I.,” we are told again and again that our genome is at the heart of our identity. Read the sequences in the chromosomes of a single cell, and learn everything about a person’s genetic information.

But scientists are discovering that […] it’s quite common for an individual to have multiple genomes. Some people, for example, have groups of cells with mutations that are not found in the rest of the body. Some have genomes that came from other people. […]

In 1953, a British woman donated a pint of blood. It turned out that some of her blood was Type O and some was Type A. The scientists who studied her concluded that she had acquired some of her blood from her twin brother in the womb, including his genomes in his blood cells.

Chimerism, as such conditions came to be known, seemed for many years to be a rarity. But “it can be commoner than we realized,” said Dr. Linda Randolph, a pediatrician at Children’s Hospital in Los Angeles.

Twins can end up with a mixed supply of blood when they get nutrients in the womb through the same set of blood vessels. In other cases, two fertilized eggs may fuse together. […] Women can also gain genomes from their children. After a baby is born, it may leave some fetal cells behind in its mother’s body, where they can travel to different organs and be absorbed into those tissues. […] In 2012, Canadian scientists performed autopsies on the brains of 59 women. They found neurons with Y chromosomes in 63 percent of them. The neurons likely developed from cells originating in their sons. […]

Medical researchers aren’t the only scientists interested in our multitudes of personal genomes. […] Last year, for example, forensic scientists at the Washington State Patrol Crime Laboratory Division described how a saliva sample and a sperm sample from the same suspect in a sexual assault case didn’t match.

{ NY Times | Continue reading }

I could ask her perhaps about how to pronounce that voglio

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First Genetic Evidence That Humans Choose Friends With Similar DNA

The discovery that friends are as genetically similar as fourth cousins has huge implications for our understanding of human evolution, say biologists.

{ The Physics arXiv Blog | Continue reading }

and drew him down to me so he could feel my breasts all perfume

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The sense of smell is one of our most powerful connections to the physical world. Our noses contain hundreds of different scent receptors that allow us to distinguish between odours. When you smell a rose or a pot of beef stew, the brain is responding to scent molecules that have wafted into your nose and locked on to these receptors. Only certain molecules fit specific receptors, and when they slot together, like a key in a lock, this triggers changes in cells. In the case of scent receptors, specialised neurons send messages to the brain so we know what we have sniffed. […]

In the last ten years, however, reports have trickled in from bemused biologists that these receptors, as well as similar ones usually found on taste buds, crop up all over our bodies.

{ BBC | Continue reading }