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The captivating scent of cakes and the compelling aroma of freshly brewed coffee attract you to a bakery in the morning. A male moth is flittering around, frenetically following the scent plume released by her female. What do these two phenomena have in common? Much more than we suspect, when we look at the molecular level. Imagine if we had a very powerful microscope enabling us to detect details

The post The importance of smell appeared first on OUPblog.

Molecular biology continues to inform science on a daily basis and reveal what it means to be human beings as we discover our place in the universe. With the ability to engage science in ways that were unimaginable only a few decades ago, we can obtain the genetic profile of a germ, discover the roots of unicellular life and uncover the mysteries of now extinct Neanderthals.

In One Plus One Equals One, author John Archibald unmasks the wonders of biotechnology, showing readers how evolution has interacted with the subcellular components of life from the beginning to present day. With molecular biology, we can look back more than three billion years to reveal the microbial activities that underpin the development of complex life, just as we can look at the inner workings of our own cells. Take a look around and ask yourself, how much do you know about the world around us?

Headline image credit: HINGOLGADH. Photo by Kalpeshzala59. CC BY-SA 3.0 via Wikimedia Commons.

The post The evolution of life appeared first on OUPblog.

        

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By Qiliang Ding and Ya Hu

Hominins and their closest living relative, chimpanzees, diverged approximately 6.5 million years ago on African continent. Fossil evidence suggests hominins have migrated away from Africa at least twice since then. Crania of the first wave of migrants, such as Neanderthals in Europe and Peking Man in East Asia, show distinct morphological features that are different from contemporary humans (also known as Homo sapiens sapiens). The first wave of migration was estimated to have occurred 7-9,000,000 years ago. In the 1990s, studies on Y-chromosome and mitochondrial DNA proved that the contemporary Eurasians are descendants of the second wave of migrants, who migrated out of Africa less than 100,000 years ago.

It has been reported that the habitats of Neanderthals and ancestors of contemporary Eurasians overlapped both in time and space, and therefore provides possibility of introgression between Neanderthals and ancestors of Eurasians. This possibility is confirmed by recent studies, which suggest that about 1-4% of Eurasian genomes are from Neanderthal introgression.

Adaptation to local environment is crucial for newly-arrived migrants, and the process of local adaptation is sometimes time-consuming. Since Neanderthals arrived in Eurasia ten times earlier than ancestors of Eurasians, we are trying to figure out whether the Neanderthal introgressions helped the ancestors of Eurasians adapt to the local environment.

Two major out-of-Africa migration waves of hominins. The purple and red colors represent the first and second migration waves, respectively. The circle near Middle East represents a possible location where main Neanderthal introgression might have occurred.

Our study reports that Neanderthal introgressive segments on chromosome 3 may have helped East Asians adapting to the intensity of ultraviolet-B (UV-B) irradiation in sunlight. We call the region containing the Neanderthal introgression the “HYAL” region, as it contains three genes that encode hyaluronoglucosaminidases.

We first noticed that the entire HYAL region is included in an unusually large linkage disequilibrium (LD) block in East Asian populations. Such a large LD block is a typical signature of positive natural selection. More interestingly, it is observed that some Eurasian haplotypes at the HYAL region show a closer relationship to the Neanderthal haplotype than to the contemporary African haplotypes, implicating recent Neanderthal introgression. We confirmed the Neanderthal introgression in HYAL region by employing a series of statistical and population genetic analyses.

Further, we examined whether the HYAL region was under positive natural selection using two published statistical tests. Both suggest that the HYAL region was under positive natural selection, and pinpoint a set of single nucleotide polymorphisms (SNPs) contributed by Neanderthal introgression as the candidate targets of positive natural selection.

We then explored the potential functional importance of Neanderthal introgression in the HYAL region. The HYAL genes attracted our attention, as they are important in hyaluronan metabolism and cellular response to UV-B irradiation. We noticed that an SNP pinpointed as a potential target for positive natural selection was located in the most conservative exon of HYAL2 gene. We suspect that this SNP (known as rs35455589) may have altered the function of HYAL2 protein, since this SNP is also associated with the risk of keloid, a dermatological disorder related to hyaluronan metabolism.

Next, we interrogated the global distribution of Neanderthal introgression at the HYAL region. It is observed that the Neanderthal introgression reaches a very high frequency in East Asian populations, which ranges from 49.4% in Japanese to 66.5% in Southern Han Chinese. The frequency of Neanderthal introgression is higher in southern East Asian populations compared to northern East Asian populations. Such evidence might suggest latitude-dependent selection, which implicates the role of UV-B intensity.

We discovered that Neanderthal introgression on chromosome 3 was under positive natural selection in East Asians. We also found that a gene (HYAL2) in the introgressive region is related to the cellular response to UV-B, and an allele from Neanderthal introgression may have altered the function of HYAL2. As such, we think it is possible that Neanderthals may have helped East Asians to adapt to sunlight.

 Qiliang Ding and Ya Hu are MSc Students at the Institute of Genetics at Fudan University and Intern Students at the CAS-MPG Partner Institute of Computational Biology of the Chinese Academy of Sciences. Their research interest lies in revealing evolutionary history of hominids using ancient and contemporary human genomes. They are the authors of the paper “Neanderthal Introgression at Chromosome 3p21.31 Was Under Positive Natural Selection in East Asians,” which appears in the journal Molecular Biology and Evolution.

Molecular Biology and Evolution publishes research at the interface of molecular (including genomics) and evolutionary biology.

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Image credit: Background map via Wikimedia Commons, with annotations by the authors. 

The post Neanderthals may have helped East Asians adapting to sunlight appeared first on OUPblog.

        

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By Cassie Ammerman- Publicity Assistant

Richard Dawkins is the bestselling author of The Selfish Gene and The God Delusion. He’s also a pre-eminent scientist, the first holder of the Charles Simonyi Chair of the Public Understanding of Science at Oxford, and is a fellow of New College, Oxford. Called “Darwin’s Rottweiler” by the media, he is one of the most famous advocates of Darwinian evolution. His most recent book is The Oxford Guide to Modern Science Writing, a collection of the best science writing in the last century.

This is the first in a series of podcasts we’ll be running from an interview with Richard Dawkins. In it, Dawkins talks about the different scientists he chose to include in The Oxford Book of Modern Science Writing. In this selection, Dawkins talks with Dorian Devins about James Watson and Francis Crick, the two men famous for discovering the structure of DNA.

Transcript after the jump.

DORIAN DEVINS: Francis Crick is one of the people in here, and I know you…

RICHARD DAWKINS: Yes, I met him a couple of times. I know Jim Watson rather better. Francis Crick died a couple of years ago. He was of course the other half of Watson and Crick, and they were both indispensable. It’s a wonderful illustration of how two people coming together seem to make something that’s greater than the sum of their parts. Francis Crick has written a number of books. He’s always very thoughtful, very stimulating. It’s impossible for him to say anything that isn’t interesting, and he was one of the great, possibly the greatest, intellects of the molecular biology revolution, which started with Watson and Crick in 1953, when they were both young men. But Crick went on to in a way dominate the field. I mean, in the elucidation of the genetic code, the fact that it’s a triplet code, for example, he played a leading role in that. So he became a kind of elder statesman of molecular genetics, and then rather later in his life, he switched completely to a totally new field, which was the study of consciousness. And he was never really a proper neurobiologist, but he sort of somehow managed to well, use his eminence in the field to open doors to talk to neurobiologists. And once again, he was a very, very thoughtful, stimulating figure in that field, as well as his own field of molecular genetics.

DEVINS: Whereas I guess Watson, more or less, stuck to genetics, although he did…

DAWKINS: Yes he did stick with genetics, and Watson was pretty much involved in initiating the human genome project. He didn’t stay in the human genome project, but he was largely responsible for getting it started in the first place.

DEVINS: And their writing styles are so different. It’s interesting.

DAWKINS: Yes, well, that’s right. Watson’s writing style is amazingly readable, but very odd. I mean, it’s…any teacher of English would blue-pencil it straight away. He had a most weird tendency to stick strings of adjectives before a—not so much adjectives, more phrases that count as adjectives—so he’ll say, if he wants to say he walked by, well quite close to here is Keble College (which is the Victorian building designed by Butterfield), Watson will say “I walked by the Butterfield-designed Keble College.” Sticking an adjective, making a phrase into an adjective, and then sticking it before the noun. And it’s an odd way of writing, but for some reason, it’s very readable, and I find that his books are page turners in a way that any teacher of English would sort of veto.

DEVINS: It’s funny how the personalities come out in the writing sometimes.

DAWKINS: Yes, that’s true. I think it’s part of the personality, and I think it’s because Watson writes in such an irresponsible way. He doesn’t mind who he offends, and so you’re always kind of turning the page, waiting for the next bit of scandal really.

DEVINS: As he is in life.

DAWKINS: Yes.

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The family is here for Christmas--let the games begin.

Note: Not head games; real games, the kind you can win.

What better way to spend time together with family than by smearing them into the ground with your superior game-playing skills? Here are the games that will be played in the Haworth house: You Don't Know Jack, Yahtzee, and Scrabble.

You Don't Know Jack is a computer trivia game that feels like a live action game show. I AM THE UNDISPUTED CHAMPION. People I've beaten include one of my brothers, my mom, my sister, my sister's friend, and my husband. My husband thinks I win because I'm faster than he is, but really it's cuz I'm smarter. I win every time I play. I AM THE CROWNED VICTOR and no one even comes close. At the start of the game, players must enter their names; everyone else enters their given name. I enter W-I-N-N-E-R. I figure that saves everyone a little time at the end.

Yahtzee--what can I say? We love this game. It was my dad's favorite. We love to rattle the dice and jar non-playing visitors with the noise.

Scrabble--You're talking serious stuff here, folks. Long before I was even thought of, my mom and dad stayed up many late nights with my grandma playing Scrabble. Grandma had only a sixth grade education, but she'd win with words like c-a-t. Somehow she always hit the specials.

I do not always win at Scrabble, but I like to make my opponents think I do. Again, I list my name as "Winner." Others are intimidated by the fact that I own a regular board and a travel board as well. (You do not want to get caught without your Scrabble board.) I employ the power of the Challenge, something your less hearty players will not do; they think they're in it just for the fun. My brothers and sister and I know better: we play to win, and we play cutthroat. We are equally as good and my trash talk doesn't work with them because we've all got the same mom.

In any case, the gang's all here (except for you, little bro). Let the games begin! MERRY CHRISTMAS!