Javier Aguilar1, Carlos Mas2, Luis Losinno1 y Adrián Filiberti2.
1Produccion Equina, Universidad Nacional de Río Cuarto (jaguilar@ayv.unrc.edu.ar), 2CEPIDEM, Fac. Cs. Medicas, Universidad Nacional de Córdoba (carlos@dqb.fcq.unc.edu.ar)

Currently we are witnessing a revolution in science and we hear scientists and experts daily announcing the identification of new genes, new genetic mutations which are the cause of diseases, the creation of transgenic animals, etc.
But what do these complex words really mean? How can these advances be of use to us? How near to our everyday life are they?

We are led to speculate on the importance of these advances when we see the interest shown in them by developed countries. As from a few years ago a consortium of state and private pharmaceutical companies have provided large sums of money ( approximately 7,000 million dollars) for a group of scientists to discover the human genetic makeup – The Human Genome Project.

In 1999 the president of the USA announced that this project was almost ended and that the impact of the information was so enormous it could not be owned by any one company but belonged to humanity as a whole and the first draft of the human genome was published.

At the same time, since the mid 90’s a project known as the International Equine Gene MappingWorkshop is underway thanks to the collaboration of a consortium of pharmaceuticals from the USA, France, UK, Japan and Australia.

At this point in time the first part of the equine genomic map has been published and it is expected the second part will be finished this year.

But why are we interested in knowing the genetic makeup of horses? Why has so much time and money gone into this effort?
Basically because knowledge of the genes of animals, and in this case horses, can be immediately applied so as to substantially modify equine production.

To put it in other words, genetic information correctly interpreted by trained scientists is…money.

Alvin Toffler (writer, researcher and social communicator) said that the economic history of humanity could be divided into three eras: the first was the era of agriculture and the written work, the second era was the era of capital and industry and the current era is the era of information and knowledge.

Basically, knowing the genetic makeup of horses will allow the breeder to know, for example, if a stallion has greater or lesser fertility, if he will transmit a genetic disease to all his get, how his sperm will react to freezing techniques and in the case of mares the probability that they will have multiple ovulations, their response to superovulation techniques, etc.
(Murray,J.D. Horse genomics and Reproduction, VIII International Symposium on Equine Reproduction, Ft. Collins, USA, Julio, 2002)

All the characteristics of a horse are determined by its genes and the effects of the environment in which it develops. Genes determine the coat colour, eye colour, height, and the greater tendency to suffer different diseases.

Genes are parts of a moleculle known chemically as DNA or Desoxirribonucleic acid, they are within the cell nucleus which is where they carry out their activities.

DNA can be graphically represented as two strands or ribbons which face each other and twine round each other, fitting exaclty into each other, rather like a zip (see illustration). In a zip the teeth are all the same, but in DNA these “teeth” are called nucleotides and there are 4 different types: Adenine (A), Cytosine (C), Guanine (G) and Thymine (T). IN the nucleus of each human cell there are about 3,000 million nucleotides in each strand of DNA. Their lineal sequence for example, in one case, may be ATTTGTGTCCATGCGACTCTCACGC.

To read DNA is to learn this sequence, that is in the example to know that the first nucleotide is A the second T, etc. This sequence contains the information responsible for the diversity of life, that is to say the DNA of an orchid contains the same four nucleotides (A, T, C, G) as the DNA of a human being, a hummingbird or a horse. The only thing that varies is its lineal sequence.

Every living cell possesses the mechanism necessary for “reading” this sequence of DNA nucleotides and by means of a complex process to translate it so as to form another molecule known as a protein.

To put it simply a gene is a portion of DNA capable of producing a protein. In this manner the biochemical machinery of a cell, using the information contained in the DNA, is capable of synthesizing thousands of different proteins according to the nucleotide sequence of the DNA which acted as a template.

Now that the Human Genome is known and therefore human DNA sequence, and this has been “trnaslated” using biocomputer methods, 30,000 different proteins have been determined to correspond to 30,000 genes. Proteins carry out the basic biochemical tasks that maintain life. The 30,000 genes present in each of our cells determine that we are who we are. In general terms we may say that the difference between a human being and a hummingbird is, precisely, that they have different genes – that is to say different DNA sequences – which produce different proteins.

Between two different species – humans and hummingbirds for example – there are more genetic differences than within one species. And within one species there are more differences between non-related individuals than between related individuals. The closer the realationship, less will be the genetic differences.

It must be mentioned that there are portions of DNA which are also called genes which do not synthesize proteins and to greater complicate matters there are genes that synthesize more than one protein.

By means of genetic analysis horse breeders could correctly plan services so as to avoid the transmission of genes with defects to the next generation.

This type of analysis, both trustworthy and useful, would be a powerful diagnostic tool in horse selection and would allow the improvement of horse breeds and serve to determine the exclusion of horses from prestigious associations’ books both in the USA and in Europe.

The strictly practical uses of our current knowledge of DNA which can be applied to horse breeding are two:
1) The determination of paternity .
2) The detection of animals who are transmitters of genetic diseases and the ability to predict the coat colour.

The genetic diseases which can currently be determined by means of DNA analysis are three:
a) Syndrome of Severe Combined Inmunodeficiency (SCID).
b) Hypercalcaemic Periodic Paralysis (HYPP)
c) Lethal White Piebald Foal Syndrome (SLPOB)

In plain words what is currently being done

The Pilot Centre for the Detection of Metabolic Errors CEPIDEM, which belongs to the School of Medicine of the University of Cordoba, Argentina (Facultad de Ciencias Médicas de la Universidad Nacional de Córdoba) offers a service called SCID and will soon offer HYPP and SLPOB.

We believe that breeders working on genetic improvement programs may find these tools to detect hereditary diseases in horses useful.

Scientists have put a lot of effort into desciphering the mechanisms by means of which a small alteration in a cellular component leads to a disease. These tools are very powerful if properly used and can help us to be on the cutting edge o technology. They are used by developed countries, well aware of their enormous potential, to maintain their leadership.

.