Human Chromosomes Mass Measured For the First Time in 130 Years

To measure, researchers used X-ray beams 'billions of times brighter than the Sun.'
Fabienne Lang

In a study led by UCL researchers in the U.K., the mass of human chromosomes has been measured for the first time using X-rays. 

The implications of understanding the mass of chromosomes could be important in the field of medicine, as they contain the instructions for life in nearly every cell of our bodies, as the UCL researchers explain in their paper published in Chromosome Research.

Interestingly, the team found out that the chromosomes were heavier than they anticipated, as they were approximately 20 times heavier than the DNA they contained. This means that there might be missing parts that have yet to be discovered — something that could further medical understanding of the human body. 

DNA's mass was already understood, but not the masses of chromosomes'. 

Senior author of the study Professor Ian Robinson said "Chromosomes have been investigated by scientists for 130 years but there are still parts of these complex structures that are poorly understood."

Understanding precisely how chromosomes work, including their mass, is critical for medical labs, as "A vast amount of study of chromosomes is undertaken in medical labs to diagnose cancer from patient samples. Any improvements in our abilities to image chromosomes would therefore be highly valuable," explained Archana Bhartiya, a Ph.D. student at UCL, and lead author of the study.

How the team calculated the chromosomes' mass

In order to calculate the mass, the team used a powerful X-ray beam from the U.K.'s national synchrotron facility, Diamond Light Source, to determine the number of electrons across 46 chromosomes in order to calculate mass. 

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The method the researchers used is called X-ray ptychography, which creates a highly sensitive 3D reconstruction of the chromosomes. The team was able to get such fine resolution as the beam used at Diamond Light Source is billions of times brighter than the sun. 

The chromosomes were imaged in metaphase, right before they were about to divide into two daughter cells.

Just last year, a chromosome was completely sequenced for the time first ever, and another study used 3D imaging to show us that chromosomes don't always take the X shape we're taught in biology class. 

As Bhartiya said "A better understanding of chromosomes may have important implications for human health."