Photo courtesy: Wikipedia
Ranger Rani has a puzzle for you. If an animal is big in size, does the genome of the animal have to be big too? Ranger Rani thinks not. What do you think?
Looking for complete animal genome is like looking for a needle in a haystack. With so many animals, each with lots of genes, how do scientists decide which critter goes first?
For Ranger Rani, that's an easy answer. She says pick up an endangered species! We need all the information we can get to save the species. Unfortunately, there are thousands of species in the endangered list. Which one to choose from?
Scientists recently chose the panda. Like nature lovers everywhere, including you, Ranger Rani was delighted too.
But first, Ranger Rani has a question. What does the sequence of the entire genome tell us? The genome includes all the genetic information that is hidden on the entire DNA sequence. That's lot of genes on chromosomes. The genes code for proteins. And proteins do the work at the chemical level. That is like sifting through millions and zillions of types of proteins created by our body. That's a lot of work. Yet, recent advances in scientific methods make it easy to achieve this task. If we are lucky, we can do this in less than 6 months.
One of the first things scientists look for is the size of the genome. Led by Chinese scientists, experts from all over the world joined in this effort. The panda genome has only 3 million base pairs.
But the size doesn't mean much. The 3 million base pairs have code for about 21,000 genes that code for proteins. That is about the size of the genes that code for proteins in humans too.
In recent years, panda population has rapidly declined. In the last ten years, the population has decreased by 92%. Scientists hypothesized that this rapid decline was due to inbreeding. Inbreeding happens when no new genes enter into the population and causes the population to have illness or have susceptibility to a disease.
The panda genome showed no signs of inbreeding. Pandas have double copies of DNA in each of their cells. Each of these copies isn't exactly identical. This condition is called heterozygosity.
Yet, the panda's genetic makeup changes little from generation to generation. Other mammals, especially humans, have rapid change of genes between generations. Scientists use this information to understand the rate of evolution in animals. When there is little change in genetic material from one generation to next, the rate of evolution is slow. Such animals are considered to be 'living fossil.'
The biggest surprise happened when the panda genome was analyzed for the diet. The panda, it turns out, isn't all that well equipped to eat its favorite food: bamboo. The taste gene called T1R1 senses the taste of meats, cheese, broth and other high-protein foods. It makes these foods tasty. This gene is mutated in pandas. This means the pandas couldn't taste meat. Did this mutation push them towards the bamboo diet? Scientists are studying that more closely.
Yet, the panda has a unique problem. It has all the required genes to digest meat, but it doesn't eat meat. Due to the mutations in the gene, it can't even sense the meat by smell. But, the panda has no genes to digest the bamboo it eats by tons!
So, how does the panda digest the bamboo? It turns out that pandas rely entirely on the microbes found in the guts. These microbes help panda to extract nutrients from bamboo.
Scientists are now realizing that all creatures, great and small, have to rely on the microbial genes. It is this interaction that makes each one of us unique. Like pandas, we too are unique. In the end that's what counts!
