knowing the dark matter of genome

Scientists have revealed the dark matter of human genome through their comparison of genomes of 29 mammals. The dark matter is not literally dark. It helps controlling where genes would turn on. This would certainly help in dealing with certain diseases. But it is more important to have served to human quest about working of human genome.

It is not for the first time that genomes of different animals are compared or that genomes of different mammals are compared. It is a well-established interesting fact that it is only in a few percent of our genome that we differ from other mammals. And regions of critical concerns are those that are same with all mammals as any disruptions in these areas cause human diseases.The regulation of genes through the process of cell differentiation is far more important than the expression of genes itself. It has interestingly been the mouse, which has been subject for genome comparison. What comprised earlier of indirect results has now been confirmed by so many comparisons thanks to rigorous experiments by scientists.

Why are the sections of human genome named as dark matter of genome? It is only because of the blank or scanty knowledge about these and nothing else. It should yet be clear that these parts don’t have any functional genes. Their crucial importance lies in their role in gene regulation and cell differentiation.


What is gene regulation and cell differentiation?

Every human being starts as a single cell in mother’s womb (rather fallopian tubes mostly): the zygote that is formed out of fertilization of an ovum by a sperm. Now this cell multiplies into two same cells. The genome of the two cells is exactly same (and for that matter it is exactly same with all the trillions of cells in human body). The two cells further divide to four cells and the four into eight…into 16 …into32 …into 64 and so on. And this division continues even after birth and puberty when we and our body keep growing.

A simple logic applied on this division process tells us that all the cells thus produced should be exactly the same. But you know it is not the case.If the body of an adult has different organs and organs-systems, it has its roots in early development of fetus. This differentiation of cells that determines that a particular set of cells of an organ will produce only those particular types of cells starts quite early in the fetal development. The question is what regulates this differentiation. Because everything of a cell is governed by its genome, it means the genome must be regulateddifferently to produce differentiated cells. The mystery continues through entire course of logic as genome of all the cell is perfectly same (how can they be regulated differently). 
One thing should be clear through this discussion that the differentiation of cells in our body that has got different types of cells and tissues to make quite dissimilar organs (compare eyes and bones, for example) has to do with cell differentiation and regulation of genome.

The quest for- and the success:

Most parts of our genomes consist of this dark matter (about which we are honestly in dark!) and we don’t have succeeded in exploration of this matter in most of the mammals. The search for ways – both direct and direct – is on for this. This time a comparison of genome of rabbit, bat, elephant and others –a total of 29 placental mammals -- has been tried. In some cases it is still not possible to peep into this matter but some 3 million points that don’t code genetic information to be expressed in animals have been identified.The contributions from the Genome Institute (Washington University), Baylor College of Medicine and Broad Institute in mapping the genomes of different mammals have provided the basis for this discovery.Hope this dark matter will not remain dark anymore!