Molecular Genetics

Males, who needs ‘em?

moon — Wed, 03 Mar 2010 17:23:00 +0000

(submitted by LH) In the United States, there is essentially one male for every female. But this series of graphics illustrates that this is not always the case. There are many factors that play into a shift from a bevy of males at birth to a dearth of them at death. Biologically, male humans are more susceptible X-linked diseases than females. Having only a hemizygous state more than doubly increases the likelihood of inheriting a disease allele from a heterozygous mother. There is also the argument that males typically have more dangerous professions and are the major component of combat. Or are simply more likely to endanger themselves.
However, some societies will favour a particular gender over another and will select the sex of their child through IVF. This has led to problems in some countries as the disparity begins to impact the economy and social constructs like marriage.

Very early mugshots

moon — Wed, 03 Mar 2010 17:01:18 +0000

(submitted by JH) The lone star state of Texas unwittingly set off a firestorm of controversy by collecting 800 samples of blood from new borns. The samples were to be part of a new study and database of mitochondrial DNA. The intent was to provide information for forensic science and other studies of variation, but after public outcry, the state has promised to destroy the samples.
However, this may not quell the fears of many. Some of whom may opt to not have their new borns genetically tested for known diseases; increasing the likelihood of delayed treatment.

Jurassic Park 2, Life Imitates Art

moon — Thu, 20 Nov 2008 13:39:55 +0000

(submitted by AB) Imagine a world where pigeons and squirrels frolic about campus. The occasional feral cat dashing across west mall. Rove herds of woolly mammoths grazing around the MLK statue…

It seems that the genome of the extinct mammoth has been sequenced. This will allow scientists to compare the sequences with modern elephants to study differences that might shed light on their origins and their demise.
Several new techniques were employed including isolating the DNA from only the hair of mammoth mummies. In doing this, contaminating DNA from bacteria and fungi can easily be eliminated. The hair follicles serve to protect the DNA also.

It may be possible clone portions of the mammoth’s DNA and swap it in to elephant DNA using homologous recombination. With successive generations, we could repopulate Sarahpalinia with mammoths to support the hunting tourism industry. Molecular genetics at its best.

If cats had opposable thumbs…

moon — Sun, 09 Nov 2008 14:33:40 +0000

…there would no longer be a need for humans. The last barrier to opening cat food tins would drop and humans would be reduced to warm spots.
(submitted by TK) Scientists have recently identified an enhancer that appears to affect the expression of a gene that controls the formation of the joint between the wrist and the thumb. One of the more important aspects of this discovery is that it is not a gene itself, but part of the regulatory region of several genes. This could affect the timing of when a gene is expressed; ultimately changing the orientation of the structure.
Additionally, this type of study highlights the importance of the unknown in the human genome. Long described as junk DNA, these intergenic regions may very well prove to be the primary distinguishing sequences between humans and their closest primate relatives (Chimpanzees, Bonobos, people from Arkansas…).

When dinosaurs walked the Earth…

moon — Sun, 09 Nov 2008 14:05:18 +0000

(submitted by SS) Until now, scientists have only been able to produce clones using cells from live animals. This is how researchers created Dolly the Sheep, the first mammal to be cloned from an adult animal.

Researchers had thought that frozen cells were unusable because ice crystals would have damaged the DNA. That belief would rule out the possibility of resurrecting extinct animals from their frozen remains.

Recently, scientists in Japan have generated clones from frozen mice. Mice that have been dead and frozen for 16 years. This opens the possibility of cloning mammoths and other animals that long disappeared from the extant fauna of the Earth. Jurassic Park is one step closer…

That dude is such a vole.

moon — Wed, 10 Sep 2008 15:06:07 +0000

(submitted by RH) When they say that people in love have a certain chemistry, there may be something to it. Some time ago, it was observed that voles of different species can have remarkably different behaviour. In general, very few animals are monogamous, but Prairie Voles practice an unparalleled fidelity. While their close cousins are the studmuffins of the meadow. The difference appears to be in their response to vasopressin- a hormone with many functions, among them regulating blood pressure in response to stress.
However, both species (Prairie and Meadow Voles) have similar levels of vasopressin. The difference appears to lie in where the receptors for the hormone are expressed. Those animals with one or two copies of the gene that is driven to be expressed in the brain are more faithful than those that do not have the receptor. This was confirmed when the gene was transfered in to the straying Meadow Voles, which then became doting spouses.
The gene has been identified in humans along with variants in the gene coding for the enzyme that produces vasopressin. Those men with two copies of the variant allele report consistent relationship problems. No doubt, KwikKits that test for this gene will be on store shelves soon.

A fish by any other name, still smells as icky

moon — Fri, 29 Aug 2008 16:03:05 +0000

Is that really super tuna that they are serving you? Some students recently used DNA testing to determine how often sushi-grade meat was actually the type of fish advertised. They found that one in four samples was mislabeled! The technique that they used is called genetic fingerprinting. This involves amplifying particular segments of the genomic DNA with PCR, and then comparing the relative size of the reaction products. This is similar to the DNA tests used to determine paternity. More rigorous tests are used for criminal evidence, but the principle is the same.
Of particular interest, is that in every case a lower-quality of fish was mislabeled; leading people to believe that they were eating the expensive dish that they ordered. This type of testing is being extended to other food products as they transported around the world in bulk. Other targets for DNA finger printing include prisoners, soldiers, pets, and recently, children.

Where the future and past meet: teeny robots and Lamarck’s theories

moon — Sat, 06 Oct 2007 22:42:09 +0000

Researchers say “countless” lives could be saved with a blood test to quickly and easily determine if breast cancer survivors were suffering another bout of the disease.

Experts in the cutting-edge sciences of nanotechnology and the new field of epigenetics are teaming up to develop a test with the aim of diagnosing cancer while it is still tiny, instead of waiting for a lump to appear.

The same test could be used to determine if cancer had spread from the breast to other parts of the body, and the researchers hope it could ultimately be used to screen all women for breast cancer.

Professor Matt Trau from the University of Queensland said the greatest fear for many women treated for breast cancer was that it would return and spread to other parts of their bodies.

Once a woman has advanced breast cancer, their prognosis is poor.

“Rather than having to wait anxiously to see if another lump or symptoms return, we hope to develop a blood test that would tell patients early if the cancer has returned, so they can receive treatment quickly and with more likelihood of a successful outcome,” Prof Trau said.

“That alone could save countless lives.”

The ambitious project will centre on the new field of epigenetics, modifications to genes that do not change the DNA sequence.

Epigenetic changes are thought to be one mechanism for cancers to form, and certain epigenetic “signatures” have already been found in some types of prostate and cervical cancerous cells.

Exam Anxiety

moon — Sat, 06 Oct 2007 18:18:00 +0000

“See what will happen if you don’t stop biting your fingernails?” — Will Rogers, to his niece on seeing the Venus de Milo

So you can just stop freaking about exams in this class. They aren’t so bad. All materialial will be entirely from lecture notes and handouts. However, none of this is a state secret (yet, see: DHS), so there will be many more references on the website. Since there will be more complicated issues as the course progresses, I will try to keep you updated with my “summary notes”, if they seem helpful.

When genes hang out together.

moon — Mon, 01 Oct 2007 13:31:47 +0000

This is a fascinating story of a gene fusion event. Last year, in a paper published in PNAS in collaboration with Richard Cordaux (now at the University of Poitiers, France) and Mark Batzer (LSU), the authors reconstructed the evolutionary history of a primate fusion gene called SETMAR. It serves as a good introduction to the kind of questions that arise from molecular genomics and the study of mobile DNA It will also provide an example of how transposons and other forms of so-called ‘junk DNA’ can, on occasions, make themselves useful in the genome. Finally this is a story that generated quite a bit of discussion on the web including theology, GM foods, and evolution.