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Posts tagged "genetics"

wildcat2030:

Neuroscientists identify key role of language gene
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Neuroscientists have found that a gene mutation that arose more than half a million years ago may be key to humans’ unique ability to produce and understand speech. Researchers from MIT and several European universities have shown that the human version of a gene called Foxp2 makes it easier to transform new experiences into routine procedures. When they engineered mice to express humanized Foxp2, the mice learned to run a maze much more quickly than normal mice. The findings suggest that Foxp2 may help humans with a key component of learning language — transforming experiences, such as hearing the word “glass” when we are shown a glass of water, into a nearly automatic association of that word with objects that look and function like glasses, says Ann Graybiel, an MIT Institute Professor, member of MIT’s McGovern Institute for Brain Research, and a senior author of the study. “This really is an important brick in the wall saying that the form of the gene that allowed us to speak may have something to do with a special kind of learning, which takes us from having to make conscious associations in order to act to a nearly automatic-pilot way of acting based on the cues around us,” Graybiel says. Wolfgang Enard, a professor of anthropology and human genetics at Ludwig-Maximilians University in Germany, is also a senior author of the study, which appears in the Proceedings of the National Academy of Sciences this week. The paper’s lead authors are Christiane Schreiweis, a former visiting graduate student at MIT, and Ulrich Bornschein of the Max Planck Institute for Evolutionary Anthropology in Germany. All animal species communicate with each other, but humans have a unique ability to generate and comprehend language. Foxp2 is one of several genes that scientists believe may have contributed to the development of these linguistic skills. The gene was first identified in a group of family members who had severe difficulties in speaking and understanding speech, and who were found to carry a mutated version of the Foxp2 gene. In 2009, Svante Pääbo, director of the Max Planck Institute for Evolutionary Anthropology, and his team engineered mice to express the human form of the Foxp2 gene, which encodes a protein that differs from the mouse version by only two amino acids. His team found that these mice had longer dendrites — the slender extensions that neurons use to communicate with each other — in the striatum, a part of the brain implicated in habit formation. They were also better at forming new synapses, or connections between neurons. (via Neuroscientists identify key role of language gene — ScienceDaily)

(via afro-dominicano)

wildcat2030:

Evolution’s Random Paths Lead to One Place
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A massive statistical study suggests that the final evolutionary outcome — fitness — is predictable.
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In his fourth-floor lab at Harvard University, Michael Desai has created hundreds of identical worlds in order to watch evolution at work. Each of his meticulously controlled environments is home to a separate strain of baker’s yeast. Every 12 hours, Desai’s robot assistants pluck out the fastest-growing yeast in each world — selecting the fittest to live on — and discard the rest. Desai then monitors the strains as they evolve over the course of 500 generations. His experiment, which other scientists say is unprecedented in scale, seeks to gain insight into a question that has long bedeviled biologists: If we could start the world over again, would life evolve the same way? Many biologists argue that it would not, that chance mutations early in the evolutionary journey of a species will profoundly influence its fate. “If you replay the tape of life, you might have one initial mutation that takes you in a totally different direction,” Desai said, paraphrasing an idea first put forth by the biologist Stephen Jay Gould in the 1980s. Desai’s yeast cells call this belief into question. According to results published in Science in June, all of Desai’s yeast varieties arrived at roughly the same evolutionary endpoint (as measured by their ability to grow under specific lab conditions) regardless of which precise genetic path each strain took. It’s as if 100 New York City taxis agreed to take separate highways in a race to the Pacific Ocean, and 50 hours later they all converged at the Santa Monica pier. The findings also suggest a disconnect between evolution at the genetic level and at the level of the whole organism. Genetic mutations occur mostly at random, yet the sum of these aimless changes somehow creates a predictable pattern. The distinction could prove valuable, as much genetics research has focused on the impact of mutations in individual genes. For example, researchers often ask how a single mutation might affect a microbe’s tolerance for toxins, or a human’s risk for a disease. But if Desai’s findings hold true in other organisms, they could suggest that it’s equally important to examine how large numbers of individual genetic changes work in concert over time. “There’s a kind of tension in evolutionary biology between thinking about individual genes and the potential for evolution to change the whole organism,” said Michael Travisano, a biologist at the University of Minnesota. “All of biology has been focused on the importance of individual genes for the last 30 years, but the big take-home message of this study is that’s not necessarily important.” (via Yeast Study Suggests Genetics Are Random but Evolution Is Not | Simons Foundation)

rhamphotheca:

Elephants Have 2000 Genes for Smell - Most Ever Found

We’ve long known that African elephants have a great sense of smell—but a new study shows that the large mammals have truly superior schnozzes.

by Christine Dell’Amore

Compared with 13 other mammal species studied, African elephants have the most genes related to smell: 2,000.

That’s the most ever discovered in an animal—more than twice the number of olfactory genes in domestic dogs and five times more than in humans, who have about 400, according to research published July 22 in the journal Genome ResearchThe previous record-holder was rats, which have about 1,200 genes dedicated to smell.

Why so many? “We don’t know the real reason,” study leader Yoshihito Niimura, a molecular evolutionist at the University of Tokyo, said by email. But it’s likely related to the importance of smell to the poorly sighted African elephant in interpreting and navigating its environment…

(read more: National Geographic)

photograph by João Nuno Gonçalves

(via simhasanam-deactivated20140822)

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)

neurosciencenews:

Unlocking the Potential of Stem Cells to Repair Brain Damage

Read the full article Unlocking the Potential of Stem Cells to Repair Brain Damage at NeuroscienceNews.com.

A QUT scientist is hoping to unlock the potential of stem cells as a way of repairing neural damage to the brain.

The research is in Developmental Biology. (full access paywall)

Research: “Mesenchymal stem cells, neural lineage potential, heparan sulfate proteoglycans and the matrix” by Rachel K. Okolicsanyi, Lyn R. Griffiths, Larisa M. Haupt in Developmental Biology. doi:10.1016/j.ydbio.2014.01.024

Image: Researchers are manipulating adult stem cells from bone marrow to produce a population of cells that can be used to treat brain damage. This image shows neural stem cells and is for illustrative purposes only. Credit Joseph Elsbernd.

academicatheism:

Squid and Humans Evolved the Same Eye

Like wings, eyes have evolved multiple times in different lineages of animals. According to a new study, humans and cephalopods evolved the same eyes through tweaks to the same gene — even though their eyes arose independently of ours.

Many genes are responsible for making the eye. One holds instructions for making light-sensitive pigments, another provides information for making the lens, and then there are genes that orchestrate it all, telling various parts when and where they need to be assembled. These are called master control genes, and for eyes, the most important one Pax-6. The ancestral Pax-6 gene controlled the formation of a very simple eye: a few light-sensing  cells working together in a primitive organism living in the Cambrian period.

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skeptv:

Chromosome 2 - What separates chimps from humans?

At the genetic level chimpanzees are almost indistinguishable from humans, so how did the formation of human chromosome 2 lead to our divergence from our primate relatives?

Geneticist Aoife McLysaght heads to Dublin Zoo to explain more…

via The Royal Institution.


(via afro-dominicano)

anthrocentric:

A History of Slavery and Genocide Is Hidden in Modern DNA

There are plenty of ways to study history. You can conduct archaeological digs, examining the artifacts and structures buried under the ground to learn about past lifestyles. You can read historical texts, perusing the written record to better understand events that occurred long ago.

But an international group of medical researchers led by Andrés Moreno-Estrada and Carlos Bustamante of Stanford and Eden Martin of the University of Miami are looking instead at a decidedly unconventional historical record: human DNA.

Hidden in the microscopic genetic material of people from the Caribbean, they’ve found, is an indelible record of human history, stretching back centuries to the arrival of Europeans, the decimation of Native American populations and the trans-Atlantic slave trade. By analyzing these genetic samples and comparing them to the genes of people around the world, they’re able to pinpoint not only the geographic origin of various populations but even the timing of when great migrations occurred.

As part of a new project, documented in a study published yesterday in PLOS Genetics, the researchers sampled and studied the DNA of 251 people living in Florida who had ancestry from one of six countries and islands that border the Caribbean—Cuba, Haiti, Dominican Republic, Puerto Rico, Honduras and Colombia—along with 79 residents of Venezuela who belong to one of three Native American groups (the YukpaWarao and Bari tribes). Each study participant was part of a triad that included two parents and one of their children who were also surveyed, so the researchers could track which particular genetic markers were passed on from which parents.

The researchers sequenced the DNA of these participants, analyzing their entire genomes in search of particular genetic sequences—called single-nucleotide polymorphisms (SNPs)—that often differ between unrelated individuals and are passed down from parent to child. To provide context for the SNPs they found in people from these groups and areas, they compared them to existing databases of sequenced DNA from thousands of people globally, such as data from the HapMap Project.

[read more]

(via afro-dominicano)

danidoroi:

Fast-Mutating DNA Sequences Shape Early Development; Guided Evolution of Uniquely Human Traits

What does it mean to be human? According to scientists the key lies, ultimately, in the billions of lines of genetic code that comprise the human genome. The problem, however, has been deciphering that code. But now, researchers at the Gladstone Institutes have discovered how the activation of specific stretches of DNA control the development of uniquely human characteristics — and tell an intriguing story about the evolution of our species.

In the latest issue of Philosophical Transactions of the Royal Society B, researchers in the laboratory of Gladstone Investigator Katherine Pollard, PhD, use the latest sequencing and bioinformatics tools to find genomic regions that guide the development of human-specific characteristics. These results offer new clues as to how the activation of similar stretches of DNA — shared between two species — can sometimes result in vastly different outcomes.

"Advances in DNA sequencing and supercomputing have given us the power to understand evolution at a level of detail that just a few years ago would have been impossible," said Dr. Pollard, who is also a professor of epidemiology and biostatistics at the University of California, San Francisco’s (UCSF’s) Institute for Human Genetics. "In this study, we found stretches of DNA that evolved much more quickly than others. We believe that these fast-evolving stretches were crucial to our human ancestors becoming distinct from our closest primate relatives."

These stretches are called human accelerated regions, or HARs, so-called because they mutate at a relatively fast rate. In addition, the majority of HARs don’t appear to encode specific genes. The research team hypothesized that HARs instead acted as “enhancers,” controlling when and for how long certain genes were switched on during embryonic development. Through experiments in embryonic animal models, combined with powerful computational genomics analyses, the research team identified more than 2,600 HARs. Then, they created a program called EnhancerFinder to whittle down that list to just the HARs were likely to be enhancers.

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thenewenlightenmentage:

This is the most accurate model yet of what DNA looks like

This is a stunning 3D map that shows how six feet of of DNA can be crammed inside a single chromosome — a space that’s only a hundredth of a millimeter across. Not surprisingly, it looks like something that would go well with meatballs.

Chromosomes, those packages of genetic material found in our cells, were discovered way back in the late 1800s, but scientists have struggled to understand the exact way DNA molecules fold into them across three-dimensions. But a new study conducted by researchers at MIT and the University of Massachusetts Medical school has resulted in the world’s first comprehensive model of the 3D organization of condensed human chromosomes.

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thenewenlightenmentage:

Scientists Discover Parts of Our Bodies Age at Different Rates

Some people age faster than others, but the discovery of a DNA body clock by UCLA researchers now shows that different parts of our bodies age faster than others. The discovery offers important insights into the aging process — and what we might be able to do about it.

This isn’t the first time that biologists have developed a mechanism for assessing age. Earlier “biological clocks” have been derived from data drawn from saliva and hormones. More crucially, there are our telomeres to consider — those fraying tips of our chromosomes that have been linked to cellular expiry dates, and by virtue, our individual rates of aging.

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(via afro-dominicano)

thenewenlightenmentage:

'Mix and match': Mixing nanoparticles to make multifunctional materials

Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have developed a general approach for combining different types of nanoparticles to produce large-scale composite materials. The technique, described in a paper published online by Nature Nanotechnology on October 20, 2013, opens many opportunities for mixing and matching particles with different magnetic, optical, or chemical properties to form new, multifunctional materials or materials with enhanced performance for a wide range of potential applications.

The approach takes advantage of the attractive pairing of complementary strands of synthetic DNA-based on the molecule that carries the genetic code in its sequence of matched bases known by the letters A, T, G, and C. After coating the  with a chemically standardized “construction platform” and adding extender molecules to which DNA can easily bind, the scientists attach complementary lab-designed DNA strands to the two different kinds of nanoparticles they want to link up. The natural pairing of the matching strands then “self-assembles” the particles into a three-dimensional array consisting of billions of particles. Varying the length of the DNA linkers, their surface density on particles, and other factors gives scientists the ability to control and optimize different types of newly formed  and their properties.

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thenewenlightenmentage:

New study changes view about the genetics of leukemia risk
A gene that helps keep blood free of cancer is controlled by tiny pieces of RNA, a finding that may lead to better ways to diagnose blood cancers and even lead to new forms of treatment, Yale School of Medicine researchers report online Oct. 10 in the journal Cell Reports.
In the past few years researchers have identified the crucial role of the gene TET2 in keeping blood cells healthy. Mutations of the gene have been found in about 20% of leukemias and indicate a poor prognosis for patients. However, the gene was thought to be irrelevant in 80% of leukemia cases.
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thenewenlightenmentage:

New study changes view about the genetics of leukemia risk

A gene that helps keep blood free of cancer is controlled by tiny pieces of RNA, a finding that may lead to better ways to diagnose blood cancers and even lead to new forms of treatment, Yale School of Medicine researchers report online Oct. 10 in the journal Cell Reports.

In the past few years researchers have identified the crucial role of the gene TET2 in keeping  healthy. Mutations of the gene have been found in about 20% of leukemias and indicate a poor prognosis for patients. However, the gene was thought to be irrelevant in 80% of leukemia cases.

Continue Reading

ucsdhealthsciences:

$6.4 Million Grant Funds Glaucoma Study in African-Americans

A study led by Robert N. Weinreb, chairman and Distinguished Professor of Ophthalmology at the University of California, San Diego School of Medicine, has received a $6.4 million, 5-year grant from the National Eye Institute, part of the National Institutes of Health, to elucidate the genetics of glaucoma in persons of African descent. 

Glaucoma is the leading cause of blindness in African-Americans. It is four to five times more likely to occur in persons of African descent, and up to 15 times more likely to cause meaningful visual impairment in this group compared to those of European descent.

The overall goal of the study, “ADAGES III: contribution of genotype to glaucoma phenotype in African-Americans,” is to identify glaucoma genes in this high-risk, minority population, particularly persons who have rapidly worsening vision. Weinreb has teamed with Jerry Rotter, MD, Distinguished Professor of Pediatrics, Medicine and Human Genetics at Harbor-UCLA Medical Center, a renowned genetics expert, to identify relevant genes, develop predictive models for glaucoma diagnosis and progression and discover new drug targets for therapies to reduce the visual impact of glaucoma blindness.

Glaucoma results in vision loss due to damage to the optic nerve, which is irreversible if undetected or untreated.  The most common form of glaucoma is called primary open angle glaucoma (POAG). The number of persons with diagnosed POAG in the United States is expected to be more 3.3 million by 2020, with millions more undiagnosed.  While glaucoma affects all races, persons of African descent are disproportionately affected.

“The lack of understanding about the cause of this disease impedes our ability to identify and treat it early in its development,” said Weinreb, who is also director of the Shiley Eye Center, part of the UC San Diego Health System. “Evidence of genetic contribution in the pathogenesis of POAG is well established. Since POAG tends to run in families, it is critical to identify the genetic basis of the disease in order to develop effective therapies for early intervention.”

“A better understanding of the relationship among the stage of disease, the rate of change, ancestry, and other important risk factors being tracked in the ongoing African Descent and Glaucoma Study (ADAGES) will allow us to evaluate the relationship between genetics, visual loss and structural damage in this high-risk group,” added Linda Zangwil, PhD, a professor of ophthalmology at UC San Diego and study co-investigator.

The study will obtain detailed phenotypes – a composite of all observed characteristics or traits of an individual – of more than 2,000 subjects, establish a repository and implement a data-coordinating center at UC San Diego, as well conduct comprehensive genetic studies.

The recruitment, enrollment and phenotyping of both established and new subjects will occur at four clinical centers: UC San Diego School of Medicine; New York Eye and Ear Infirmary; University of Alabama at Birmingham; and a private practice in the Atlanta, Ga. area.

This is how Francis Crick dealt with unwanted solicitations following the discovery of DNA.

When James Watson and Francis Crick unveiled the double-helical structure of DNA, the pair became international celebrities. But with celebrity, can come a lot of unwanted personal attention.

One of the ways Crick dealt with the barrage of letters, personal requests and solicitations that he received throughout the 1960s was the pre-printed, catch-all reply card featured up top.

According to The Francis Crick Archive at the Wellcome Library, the seventeen reply options you see listed here “are a faithful reflection of the requests [Crick] regularly received,” though there was also space to add more if he felt like it. Apparently, unsolicited solutions to “the coding problem” (the question of how just four nucleotides could code for a polypeptide containing up to twenty different amino acids) were pretty common… just not common enough to earn them a spot on the reply card. [For the Record: The Francis Crick Archive at the Wellcome Library via Futility Closet]