Discreet Meat Deceit

As you’re probably aware, horse meat has been found in many of the UK’s cheaper ‘beef’ products. This led to an investigation which discovered that this is happening all over Europe, including Sweden, Switzerland, Germany and France. Personally, I don’t mind, but a lot of people are creating a lot of noise about it, so it must be pretty important. I think maybe its the fact that people have been mislead. But how was the horse meat initially discovered in these products?

Horse head on cow body

Corse or How?

Some of the products tested showed a positive result for equine DNA – but if DNA is, at the end of the day, made of exactly the same building blocks in every living species on earth, how can you identify horse DNA from cow DNA from human DNA? Every individual living thing on the earth has their own unique DNA sequence (except identical twins) otherwise we’d all be clones of each other, and there are certain genes that must be present in each species in order to make them look how they do. An example would be the genes that give horses a single hoof and cows a cloven hoof on each foot, or the genes that give the horse one stomach chamber but the cow four.

The DNA sequences of many, many animals have been catalogued, and so if a sample of meat is subjected to a DNA test, you can compare the genetic material in the meat to the ‘generic’ horse genome, and if horse meat is present, you know you have it in your sample!

DNA

DNA

So, what are the implications of having horse meat in our burgers, lasagnes, etc? Horse meat is cheaper than beef in some countries, so using it can drive the price of products down. Horses are also fed a drug called bute as an anti-inflammatory, but it is actually lethal to humans at high enough concentrations, but you’d have to have a lot of it to kill you (it is still used as a last resort for extreme cases of spinal arthritis in humans – but only a last resort as the side effects are quite serious).

My opinion is that horse meat is leaner, apparently more succulent than beef, and is considered a delicacy in many countries, so maybe we should start too? Original post and personal blog at http://danthechemist.wordpress.com/2013/03/03/discreet-meat-deceit/

 

Losing DNA made us human

 

Written by Olivia O’Sullivan

 

A study has shown that it may be DNA we have lost which sets humans apart from our nearest primate relatives. 

The majority of mutations in DNA are harmful, and a loss of genetic information might be assumed to be catastrophic. In a paper published last week in Nature, a team of researchers from Stanford University in California have challenged this by identifying the loss of particular regions of non-coding DNA to be a key factor in shaping our unique minds and bodies, thus setting us apart from chimpanzees and the rest of the animal kingdom.

By conducting a genetic comparison of the human genome with that of a chimp and a macaque the team found 510 DNA sequences missing in humans that were present in chimps, almost all of these sequences were from the non-coding region of DNA, i.e. chunks of DNA responsible for turning genes on or off . Two regions of particular interest were the androgen receptor (AR) gene and ‘GADD45G’ – a tumour suppressor gene involved in brain development.

The AR gene is implicated in the production of hard, keratinized penile spines which are found in many mammals and play different roles in different species. It is thought that penile spines may have been used as a way of competing with other males for mating partners by removing the sperm of competitors. It is believed that the molecular changes resulting in a loss of human penile spines has allowed us as a species to form more complex social structures by adopting monogamous reproductive relationships.

Another ‘lost section of DNA’ in humans was found to code for a tumour suppressor gene that normally acts to suppress brain growth, putting an evolutionary brake on the growth of specific brain structures zones in our primate relatives. This ultimately paved the way for the evolution of a larger human brain, giving us an intellectual edge over our fellow animals.

The results of this study certainly underlines the fact that genetic information is both gained and lost during evolution and that despite sharing approximately 96% of our DNA with chimpanzees, it is thought that this genetic divergence may have occurred more than 800,000 years ago when our ancestors split from the Neanderthal lineage. This is an exciting finding, opening up new areas for discovery through the analysis of the remaining 508 DNA sequences which promise to reveal further secrets about the molecular basis of human individuality.

 

References:

McLean, C. Y. et al. Nature 471, 216-219 (2011)

Life, but not as we know it

 

Michaela Livingstone


A newly discovered bacterium uses the deadly arsenic to grow and live.


The only organism able to use a different chemical from the accepted fundamental building blocks of life has been found living in a lake in California, substituting phosphorus for the usually poisonous element arsenic, opening up questions on what other forms of life might be possible in the universe.


Until now, all life on Earth has been found to use the same basic building blocks for life, the elements carbon, hydrogen, oxygen, nitrogen, phosphorus and sulphur. These elements make up the various cellular parts and machinery from DNA to proteins and lipids.


The bacterial strain, named the not-so-exotic GFAJ-1, was isolated from mud samples collected from the shores of the briny Mono Lake in California, known to have high levels of arsenic, by NASA researcher Felisa Wolfe-Simon and was reported in a research article in this week’s issue of the journal Science.

Phosphorus is contained in a phosphate form (phosphorus and oxygen) in the backbone of DNA and RNA, as well as energy-carrying molecules such as ATP. There had been suggestions that arsenic in the form of arsenate could be used by life as it is chemically similar to phosphate, which is why it is usually deadly.


The bacterium was shown to have arsenate incorporated in to its DNA and other cellular parts when grown in media lacking phosphorus but containing a relatively high level of arsenic. The organism was however still able to grow faster in the presence of phosphorus.


Some researchers have hailed this as evidence that it is possible for life elsewhere in the universe to use different chemicals as their building blocks, opening up many possibilities for extraterrestrial environments where life could thrive, where before it was thought impossible. It suggests that anything is possible and that alien life may look very different from what we have assumed, if we ever come face to face with it.


Others say it opens up questions as to how, and how many times, life may have evolved here on Earth speculating that life may have evolved in harsh environments with high levels of arsenic such as volcanic vents on sea beds before later incorporating phosphorus.


Clara Chan, a geomicrobiologist from the University of Delaware, Newark was reported by the journal Science as saying that the strongly held belief is that the chemistry of life is so specific that any changes would not be tolerated, “The implication of this work is that life can be quite different from what we know.”


Other scientists are less convinced by the data, withholding belief that the organism really is able to use arsenate in place of phosphate until more data is produced to show that the arsenate isn’t simply being stored in the bacterium.


GFAJ-1 at least shows that is possible for life to exist in the absence of phosphorus. Wolfe-Simon hopes now to find bacteria growing naturally in high-arsenic but low phosphate-containing environments to find proof of life that depends on arsenic.

 

Find the original research article here:

http://www.sciencemag.org/content/early/2010/12/01/science.1197258