Genetics & Molecular Biology

In the 150 years since the publication of Charles Darwin's 'Origin of Species',  despite consistent patterns of biodiversity identified over space, time, organism type and geographical region, there still remain two views of the process of 'speciation', the evolutionary process by which new biological species arise.

The first requires a physical barrier;  a glacier, mountain or body of water that separates organisms,  enabling groups to diverge until they become separate species. In the second scenario, an environment favors specific characteristics within a species, which encourages divergence as members fill different roles in an ecosystem. 
Scientists in Atlantic Canada say they have found a gene that may play a role in skin aging. Researchers were investigating the genetic cause of a rare disorder known as cutis laxa type 2 (CL2), which causes skin on the hands, feet and face to be loose and older looking, as well as growth and developmental delays including effects on the brain. In the process, researchers found some interesting correlations with the synthesis of proline, a chemical associated with skin and joint health.

Several maritime Canadian families with CL2 were identified by clinicians at the IWK Health Centre’s Maritime Medical Genetics service.

A single evolutionary event appears to explain the short, curved legs that characterize all of today's dachshunds, corgis, basset hounds and at least 16 other breeds of dogs.

The research team led by the National Human Genome Research Institute (NHGRI) scientist Elaine Ostrander, Ph.D., examined DNA samples from 835 dogs, including 95 with short legs. Their survey of more than 40,000 markers of DNA variation uncovered a genetic signature exclusive to short-legged breeds. Through follow-up DNA sequencing and computational analyses, the researchers determined the dogs' disproportionately short limbs can be traced to one mutational event in the canine genome - a DNA insertion - that occurred early in the evolution of domestic dogs. 
A gene called Chd1 has been identified in a Nature study as crucial for embryonic stem cell pluripotency - the ability to differentiate into any type of cell.  Chd1 seems to act by keeping the genetic material open and there poised to express any gene. Chd1 is also shown to be fundamental when reactivating differentiated tissue cells in order to create new stem cells.

The discovery has implications, not only for a better understanding of stem cells unique characteristics, but also for the process of obtaining them from tissue-specific cells avoiding all the problems associated with embryonic stem cells.
I'm a G-protein coupled receptor (GPCR) fan, and all of you should be too. Most drugs, from pot to tylenol, act on G-protein Coupled Receptors. The pharmaceutical industry would be helpless without them.

For a quick primer on GPCRs, you can try to decipher this picture:




Or just check out Wikipedia.

Scientists have discovered the gene behind Recessive Omodysplasia, a rare skeletal disease characterised by short-limbed dwarfism and craniofacial anomalies. The work, just published in the American Journal of Human Genetics, reports the identification on chromosome 13 of a gene - GPC6 – that is shown to be crucial for normal bone development.

The research will allow a better comprehension, as well as prevention, of the disease by permitting the screening of potential mutation carriers in pregnancy but most importantly will also help to understand better bone development and its molecular bases.
Welcome back, Moa.   Scientists say they have performed the first DNA-based reconstruction of the giant extinct moa bird using prehistoric feathers recovered from caves and rock shelters in New Zealand.

The researchers from the University of Adelaide and Landcare Research in New Zealand have identified four different moa species after retrieving ancient DNA from moa feathers believed to be at least 2500 years old.

The giant birds, measuring up to 2.5 meters and weighing 250 kilograms, were the dominant animals in New Zealand’s pre-human environment but were quickly exterminated after the arrival of the Maori around 1280 AD.

moa bird
Moa bird
How proteins recognize specific stretches of DNA is one of the key questions of gene regulation. One would like to be able to look at the regulatory DNA sequence adjacent to a gene, and predict which regulatory proteins bind there, and control the adjacent gene. In other words, we want to, just by running a few computer programs over a genome, know how the genes in that genome are regulated.
An interesting phenomenon in growing random networks:

The number of 3-node, 3-edge connected subgraphs in a random, scale-free network of N nodes scales as N0 (=1). No matter how big your network grows, you're going to have a roughly constant number of 3-node, 3-edge  subgraphs that depends only on the ratio of edges to nodes.

Let's back up a minute before we see why this counterintuitive result is so and what it means.  Imagine that we have a network made up of N nodes connected by E edges. You can start out with two nodes connected by one edge:


The Database of Useful Biological Numbers - great stuff, although before using any hard-to-measure number, be sure to know how the measurement was done before you trust the result.

Check these out:

Number of hairs in human eyebrows: 600

Respiratory cost for slow growing gradd: 2.4 mmole ATP/g dry weight * day

ATP requirement for the creation of an E. coli cell: 12-20 billion ATP molecules.

Average diameter of a protein in E. coli: 5 nm

Fraction of total body energy that is used to drive sodium/potassium pumps in the human brain: 10%

Serotonin content in pineapple: 17ug/g

Total nasal epithelial cell surface area in a mouse: 300 mm^2