International research team become the first to map pig genome
Together with an international team of scientists, researchers from the University of Copenhagen are the first to map the genome of pigs. This new knowledge can be used to better understand serious human diseases as well as to ensure sustainable pig breeding in future. The results have just been published in the scientific journal Nature.
Human genome was finally mapped in 2001. Now it’s the pig’s turn. Mapping the porcine genome provides the basis for important new knowledge about disease in humans such as Parkinson’s disease, diabetes and obesity.
“We can utilise this new knowledge in several ways. For example, the biomedical angle is highly significant, because pigs are very close to humans anatomically and physiologically. Pigs have the same genes as humans, and some of the genes with mutations that affect the development of serious disease in humans are also found as mutations in pigs. This means that pigs are an important resource for the study of the genes behind these diseases,” explains Professor Merete Fredholm, Faculty of Faculty of Health and Medical Sciences, University of Copenhagen, who has been involved in the project to map pig genome since the very beginning.
To reach the ground-breaking results, scientists isolated the DNA from a sow. They cut the DNA into small pieces that were cloned to provide multiple copies of the genetic material of pigs. The copies are the basis for so-called sequencing, which means decoding the DNA piece by piece.
Tailor-made disease counselling
“When we look at an animal that is so close to humans and study how its genes function relative to certain characteristics, we can acquire a lot of information about why people develop various diseases. For example, why some people have a greater tendency towards overweight than others,” says Professor Fredholm.
Knowledge of the pig genome will enable scientists to find a link between phenotype and genotype. A phenotype is the set of physical characteristics that can be seen and measured, in contrast to a genotype, which is the template that is determined in the genes. Because there is far less complexity within the individual races of pigs than in the human population, scientists can work out some basic mechanisms that affect the phenotypical differences associated with production characteristics as well as disease.
The scientists from the University of Copenhagen have mapped a new class of genes called non-coding RNA.
“The non-coding RNA genes allow us to understand in a completely new way basic mechanisms in many contexts, for example, in such diseases as diabetes, Alzheimer’s disease and cancer, says Professor of Bioinformatics Jan Gorodkin, head of the Center for Non-coding RNA in Technology and Health, which has contributed to these results.
Pig breeding in future
While the new findings are significant for studying disease in humans, the results will also form the basis for sustainable pig breeding in future.
“Until now, breeding has been based on selecting animals with the best production characteristics, such as those with the lowest fat per cent and greatest amount of meat, without any knowledge of the underlying genes. But the more we know about the genes of pigs, the more precisely we will be able to select breeding stock with precisely the characteristics we want. This will be key to sustainable pig breeding in future, because we will be able to breed more specifically and quickly towards phenotypic goals, and that is relevant both economically and in terms of animal welfare,” explains Professor Fredholm.
Pigs come in out of the cold
In addition to helping us become more knowledgeable about disease in humans and sustainable pig breeding, the results are also interesting from an anthropological and historical point of view. Being able to look at the entire pig genome illuminates the common history of pigs and people.
“For example, we can see how the pig was domesticated – that is, how the pig moved from living in the wild to the farmyard. The change from living in the wild to domestication left its mark on their genetic makeup. The selection process that pigs have undergone in order to become attractive production animals has left clear traces in their DNA, which we can now study,” says Professor Fredholm.
Professor Merete Fredholm
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Facts about the pig genome
Mapping genetic material means acquiring knowledge of the sequence of so-called bases in the DNA. The bases are the genetic components, and we can think of them as letters of the alphabet. Once you know the sequence of all the letters, you can read the genetic material the way you read a book. However, because the “book” is very long (~3x10^9 letters), it is not very accessible. Therefore, it is necessary to establish a relationship between genotype (knowledge of the letters) and phenotype (knowledge of which specific components of the genetic material control the various characteristics).