Posts Tagged: Genetics


14
Feb 10

First Genetic Link Between Reptile And Human Heart Evolution Found

Scientists at the Gladstone Institute of Cardiovascular Disease (GICD) have traced the evolution of the four-chambered human heart to a common genetic factor linked to the development of hearts in turtles and other reptiles.

The research, published in the September 3 [2009] issue of the journal Nature, shows how a specific protein that turns on genes is involved in heart formation in turtles, lizards and humans.

“This is the first genetic link to the evolution of two, rather than one, pumping chamber in the heart, which is a key event in the evolution of becoming warm-blooded,” said Gladstone investigator Benoit Bruneau, PhD, who led the study. “The gene involved, Tbx5, is also implicated in human congenital heart disease, so our results also bring insight into human disease.”

From an evolutionary standpoint, the reptiles occupy a critical point in

(Link)


12
Feb 10

Epigenetic Signals Differ Across Alleles

Researchers from the Institute of Psychiatry (IoP), King’s College London, have identified numerous novel regions of the genome where the chemical modifications involved in controlling gene expression are influenced by either genetic variation or the parental origin of that particular stretch of DNA. This contradicts previous assumptions that epigenetic signals are generally equal across both copies of a given region of the genome, except at a small number of known imprinted genes.

(Emphasis mine.)

(Link)


8
Feb 10

Dinosaur Comics: HeLa Cells

T-Rex on HeLa Cells :-)

(Link)


6
Feb 10

Eliezer Yudkowsky and Razib Khan talk Genetics and Psychology

Razib Khan (of the Gene Expression fame) and Eliezer Yudkowsky (of the Less Wrong, Overcoming Bias, and Singularity Institute fame) have an entertaining discussion on genetics and psychology.

(Link)


1
Feb 10

The Great Southern Migration Theory

Over at Kambiz Kamrani’s Anthropology.net, Terry Toohill has written and posted an interesting article on The Great Southern Migration Theory. The theory looks at the distribution of Y-DNA Haplogroup T (and to a lesser extent Y-DNA Haplogroup L).

I realise it’s risky to draw conclusions about ancient migrations from modern haplogroup distribution, but I believe that if we consider the possibility that Y-hap T was originally associated with some sort of a boating expansion we are easily able to explain the spotty distribution.
[...]
What is the possibility that L and T originate even further east? Y-haps N/O and P have become so widespread it’s possible to come up with almost any theory concerning their place of origin. But among L and T’s other close relations are S and M. Found in New Guinea, Melanesia and Australia, a region we know people must have reached using boats of some sort a very long time ago.

So we have evidence for a southern coastal migration. [...] The fact that Y-hap T, along with L to some extent, appears to have effortlessly established itself in all the desirable coastal and riverine ecosystems along the southern Eurasian margin suggests that this habitat was actually unoccupied until T’s expansion. And that argues against any other more ancient great southern coastal migration.

(Link)

Distribution of Y-DNA Haplogroup T

Distribution of Y-DNA Haplogroup L


1
Feb 10

King Tut’s DNA, Coming Soon

One of the great remaining mysteries of ancient Egypt, the lineage of the boy-pharaoh Tutankhamun, may soon be solved [...]

Zahi Hawass told AFP he has scheduled a news conference for February 17 [2010] in the Cairo Museum to unveil the findings from DNA samples taken from the world’s most famous pharaoh.

The announcement will be “about the secrets of the family and the affiliation of Tutankhamun, based on the results of the scientific examination of the Tutankhamun mummy following DNA analysis,” Hawass said.

(Link)

After this question is answered though, the question then becomes, was King Tut representative of Egyptians in general? And what was the Egyptian royalty (genetically) like before him?


27
Jan 10

Differentiating Ancient DNA from modern DNA contamination

[N]ew techniques were used in sequencing the genome of a young adult male known as the Markina Gora skeleton [...]
[...]
When compared with modern DNA, ancient DNA tends to show mutations at the end of molecules, the molecules break at different points in the DNA strand, and fragments of ancient DNA often are shorter than modern DNA fragments, Paabo and his Russian associates wrote in a recent issue of Current Biology.

(Link)


24
Jan 10

Aspie Dogs?

Well, maybe not quite an Aspie dog, but canine obsessive compulsiveness seems to be similar to human obsessive compulsiveness.

(Note the usual caveats about them labeling this behavior as a “disorder” where I don’t think that’s accurate, in the layman idea of what a “disorder” is.)

A canine chromosome 7 locus that confers a high risk of compulsive disorder susceptibility has been identified through a collaboration between the Behavior Service at the Cummings School of Veterinary Medicine, the Program in Medical Genetics at the University of Massachusetts Medical School and the Broad Institute at the Massachusetts Institute of Technology. The findings are published in the January 2010 edition of Molecular Psychiatry.

Obsessive compulsive disorder is characterized by time consuming, repetitive behaviors and affects about 2 percent of humans, while the equally distressing canine equivalent, canine compulsive disorder, or CCD, seems to target certain dog breeds, especially Dobermans and Bull Terriers. [...]

The chromosome 7 location most significantly associated with CCD is located within the neural cadherin-2 gene, CDH2. CDH2 is widely expressed, mediating synaptic activity-calcium flux related neuronal adhesion. Dogs showing multiple compulsive behaviors had a higher frequency of the “risk” associated DNA sequence than dogs with a less severe phenotype (60 and 43%, respectively, compared with 22% in unaffected dogs). This highly significant association of CCD with the CDH2 gene region on chromosome 7 is the first genetic locus identified for any animal compulsive disorder, and raises the intriguing possibility that CDH2 and other neuronal adhesion proteins are involved in human compulsive behaviors, including those observed in autism spectrum disorder. [...]

“The CDH2 gene is expressed in the hippocampus, a brain region suspected to be involved in OCD. In addition, this gene oversees structures and processes that are possibly instrumental in propagating compulsive behaviors — for example, the formation and proper functioning of glutamate receptors,” said Dr. Nicholas Dodman, professor of clinical sciences at Cummings School of Veterinary Medicine at Tufts University and the study’s lead author. Dr. Dodman added that “this finding is congruent with current evidence that NMDA blockers are effective in the treatment of OCD.”

The occurrence of repetitive behaviors and similarities in response to drug treatments in both canine CCD and human OCD suggest that common pathways are involved” [...]

(Link)


21
Jan 10

Familial resemblance for physique: heritabilities for somatotype components

My personal experience suggests to me that there is a high degree of heritability for somatotypes. This study is interesting in that it tries to figure out just how heritable they are.

Primary objective: To examine familial resemblance in the Heath-Carter anthropometric somatotype in a sample of 328 participants from 103 nuclear families in Northern Ontario (Canada). Methods and procedures: The three somatotype components (endomorphy, mesomorphy, ectomorphy) were subjected to principal components analysis and the resulting first principal component (PC1) was used as an additional index of physique. The four phenotypes were adjusted for age, sex and generation effects, while each of the three somatotype components was further adjusted for the effects of the other two components using regression procedures. A familial correlation model was fit to the data and used to estimate the degree of familial resemblance in somatotype. Main outcome and results: For all somatotype variables, the most parsimonious model was one in which there was no spouse resemblance and no sex or generation effects in the familial correlations. Maximal heritabilities were 56%, 68%, 56% and 64% for endomorphy, mesomorphy, ectomorphy and PC1, respectively, indicating significant familial resemblance for the Heath-Carter anthropometric somatotype. Further, the pattern of familial correlations suggests the role of genetic factors in explaining variation in human physique. Conclusions: In general, a pattern of no spouse but significant parent-child correlations implicates the role of genes on human physique, provided that mating is random with regard to these traits.

(Emphasis mine.)

(Link)


20
Jan 10

R1b1b2 map

From European man perhaps a Middle Eastern farmer