genetics
razib | February 14, 2009ScienceDaily has a report on a presentation Mark Shriver gave at AAAS meething this year:
"We started with 22 landmarks on the faces that could be accurately located in all the images," said Shriver.
These landmarks might be the tip of the nose, the tip of the chin, the outer corner of the eye or other repeatable locations. They then recorded the distances between all the points in all directions, so they had a distance map of each of the faces.
From their DNA profiles, Shriver could determine the admixture percentages of each individual, how much of their genetic make up came from each group…
razib | February 13, 2009ScienceDaily highlights an angle on the paper I blogged a few days ago, Chromosome And Surname Study Challenges Infidelity 'Myth':
"People often quote a figure of one in ten for the number of people born illegitimately," says Professor Jobling. "Our study shows that this is likely to be an exaggeration. The real figure is more likely to be less that one in twenty-five."
I didn't comment on this because there is research which contradicts the 1 in 10 number. There's a lot of variation worldwide, but among mainstream Western populations the misattributed paternity rates are on the order of 2%,…
mikethemadbiologist | February 13, 2009A recent paper in PLoS argues that variation in genes that regulate dopamine (5-HTTLPR) and serotonin neurotransmission (DRD4) influences financial risk taking: at the 5-HTTLPR gene, one homozygous form (two identical copies or alleles) took on 28 percent less risk, while those who had the '7-repeat' form of the DRD4 gene took 25 percent more risk. The Mad Biologist has issues regarding this study.
To me, the total amount of money the subjects could win (or not win) could influence the results. Someone who is risk adverse at $23 might be risk accepting at $2,300: if the participant were…
razib | February 12, 2009Extended Haplotypes in the Growth Hormone Releasing Hormone Receptor Gene (GHRHR) Are Associated with Normal Variation in Height. Here's the important bit:
In the VB cohort the height of individuals carrying the associated haplotypes were 3.8 cm and 2.5 cm shorter for males and females, respectively, and in the NB cohort 2.1 cm and 1.2 cm shorter for males and females, respectively. After correcting for sex, age and population affinity, carrying or not carrying the negatively associated haplotype accounts for as much as 1.8% of the variation in height in our two populations (0.9% without…
edyong | February 12, 2009This is the seventh of eight posts on evolutionary research to celebrate Darwin's bicentennial. It combines many of my favourite topics - symbiosis, horizontal gene transfer, parasitic wasps and viruses.
Parasitic wasps make a living by snatching the bodies of other insects and using them as living incubators for their grubs. Some species target caterpillars, and subdue them with a biological weapon. They inject the victim with "virus-like particles" called polydnaviruses (PDVs), which weaken its immune system and leave the wasp grub to develop unopposed. Without the infection, the wasp egg…
razib | February 11, 2009A burst of segmental duplications in the genome of the African great ape ancestor:
It is generally accepted that the extent of phenotypic change between human and great apes is dissonant with the rate of molecular change...Between these two groups, proteins are virtually identical...cytogenetically there are few rearrangements that distinguish ape-human chromosomes3, and rates of single-base-pair change...and retrotransposon activity...have slowed particularly within hominid lineages when compared to rodents or monkeys. Studies of gene family evolution indicate that gene loss and gain are…
edyong | February 11, 2009This is the sixth of eight posts on evolutionary research to celebrate Darwin's bicentennial.
Physically, we are incredibly different from our ape cousins but genetically, it's a different story. We famously share more than 98% of our DNA with chimpanzees, our closest living relatives. Our proteins are virtually identical and our chromosomes have more or less the same structure. At the level of the nucleotide (the "letters" that build strands of DNA), little has happened during ape evolution. These letters have been changing at a considerably slower rate than in our relatives than in other…
razib | February 10, 2009Dienekes points me to a paper, Founders, drift and infidelity: the relationship between Y chromosome diversity and patrilineal surnames:
Most heritable surnames, like Y chromosomes, are passed from father to son. These unique cultural markers of coancestry might therefore have a genetic correlate in shared Y chromosome types among men sharing surnames, although the link could be affected by mutation, multiple foundation for names, nonpaternity, and genetic drift. Here, we demonstrate through an analysis of 1678 Y-chromosomal haplotypes within 40 British surnames a remarkably high degree of…
razib | February 9, 2009Nick Wade's Darwin, Ahead of His Time, Is Still Influential is a good complement to the strained Darwin-skepticism I pointed to earlier. From the perspective of this weblog this comment was interesting:
Darwin is still far from being fully accepted in sciences outside biology. "People say natural selection is O.K. for human bodies but not for brain or behavior," Dr. Cronin says. "But making an exception for one species is to deny Darwin's tenet of understanding all living things. This includes almost the whole of social studies -- that's quite an influential body that's still rejecting…
razib | February 5, 2009Via Dienekes, Interactions Between HERC2, OCA2 and MC1R May Influence Human Pigmentation Phenotype:
Human pigmentation is a polygenic trait which may be shaped by different kinds of gene-gene interactions. Recent studies have revealed that interactive effects between HERC2 and OCA2 may be responsible for blue eye colour determination in humans. Here we performed a population association study, examining important polymorphisms within the HERC2 and OCA2 genes. Furthermore, pooling these results with genotyping data for MC1R, ASIP and SLC45A2 obtained for the same population sample we also…
gregladen | February 5, 2009I want to bring your attention to a somewhat dense and possibly inconclusive (but important) paper accompanied by a very informative overview in PLoS Biology, concerning mutations in the human genome.
Mutation rates and patterns of mutation are important for a number of reasons. For one thing, the genome itself is a data set that is both broad and deep. There is a lot of information in a given individual genome (a haploid set of genes from a person, for instance) but there is a wide range of variation in that information. So, inferences or assertions regarding the nature and distribution…
razib | February 4, 2009John Hawks notes that Neandertal genome in one week's time? I saw Svante Paabo speak in the fall and he said he was trying to get this out early in 2009, but he didn't clue us in to any surprises. Rather, he seemed to indicate that there would simply be greater precision on what he already had reported.
amillikan | February 3, 2009As the field of genetics sheds its sci-fi image and gains approval in the public eye, the possibilities unravel for mainstream commercial use. But some worry that if couples can use In-Vitro Fertilization to screen for disease during pre-implantation procedures, they could use it to select desired physical characteristics like eye color and gender as well, as dozens of couples from Australia have been traveling to the U.S. to do. But ScienceBlogger Daniel MacArthur from Genetic Future doesn't anticipate that this recent trend will catch on, and discusses why he thinks there won't be a large…
edyong | February 3, 2009Our health isn't just affected by the things we do after we're born - the conditions we face inside our mother's womb can have a lasting impact on our wellbeing, much later in life. This message comes from a growing number of studies that compare a mother's behaviour during pregnancy to the subsequent health of her child.
But all of these studies have a problem. Mothers also pass on half of their genes to their children, and it's very difficult to say which aspects of the child's health are affected by conditions in the womb, and which are influenced by mum's genetic legacy.
Take the case…
clock | February 2, 2009This shows how waves of humans spread throughout the world from their origins in Africa over a period of some 50,000 years. The video was created by geneticist Daniel Falush of University College Cork in Ireland and colleagues. For more info, go here: http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1000078
Soundtrack courtesy of Garageband
razib | February 1, 2009OK, it died soon after resurrection, and they used "brute force" methodologies.
edyong | February 1, 2009The Japanese pinecone fish searches for food with living headlights. This ÂÂhand-sized fish harbours colonies of light-producing bacteria in two organs on its lower jaw. The beams from these organs shine forward, and when night falls and the fish goes searching for food, its jaw-lamps light the way.
Elsewhere in the Pacific Ocean, the Hawaiian bobtail squid also uses luminous bacteria, but theirs act as a cloaking device. They produce a dim glow that matches the strength of moonlight from above, hiding the squid's silhouette from hungry fish below. It's a mutual relationship; the squid gets…
razib | January 30, 2009
Over at The Root Keith Adkins has a post, Sandra Laing: Born Black with White Parents:
I'm no geneticist or biologist, but it looks like Sandra is a product of an black South African and maybe a white Afrikaneer. I'm saying, it looks like somebody in her family was lying. The tests they used to prove her father's paternity could have been faulty. And what about proving her mother's maternity? Is it possible she was adopted? Is it possible Sandra's mother was "getting love" from a undeniably-black man on the side? I'm not trying to throw salt on Laing's game, I'm just not convinced…
amillikan | January 29, 2009ScienceBloggers are up in arms about the cover article of New Scientist which boldly proclaims "Darwin was Wrong." The article, authored by Graham Lawton, explains that occurrences such as horizontal gene transfer and hybridization transform the shape of Darwin's famous tree into something more like a thicket with criss-crossing branches. But some argue that new information in genetics doesn't render Darwin's model obsolete, and, moreover, that the headline is misleading and could be used as a tool for Creationists. "Very few readers will read your article. But everyone will see the cover,"…
razib | January 29, 2009A few years ago PLoS Medicine published Eight Americas: Investigating Mortality Disparities across Races, Counties, and Race-Counties in the United States. The results were:
-- Asian-Americans, per capita income of $21,566, life expectancy of 84.9 years.
-- Northland low-income rural Whites, $17,758, 79 years.
-- Middle America (mostly White), $24,640, 77.9 years.
-- Low-income Whites in Appalachia, Mississippi Valley, $16,390, 75 years.
-- Western American Indians, $10,029, 72.7 years.
-- Black Middle America, $15,412, 72.9 years.
-- Southern low-income…