DNA could be partially determined by factors such as diet and stress according to new research.
Researchers at the University of Edinburgh found some characteristics are determined by histones, the protein spools found in cells which DNA strands wrap around to form the characteristic double helix, rather than everything being inherited from parents.
The study is the first time DNA – the molecules containing the biological instructions for cell reproduction – has been proven not to completely determine what genetic material is passed on from parents to children. This could indicate that environmental factors could affect which genes are passed on, although further studies would need to be conducted to determine whether or not this is the case.
Environmental Changes to Genes
The study’s lead, Professor Robin Allshire, made it clear how amazing the discovery was describing it as “a holy grail in the field.” He added: “We’ve shown without doubt that changes in the histone spools that make up chromosomes can be copied and passed through generations. Our findings settles the idea that inherited traits can be epigenetic, meaning that they are not solely down to changes in a gene’s DNA.”
The researchers carried out experiments in a yeast, with similar gene control mechanisms to human cells. They introduced changes to a histone protein, mimicking those that occur naturally, causing it to switch off nearby genes. The effect was inherited by subsequent generations of yeast cells, indicating it may be possible that external factors could influence which genes are inherited by children in a similar way, but again more research would be required.
Prof Allshire said: “There is some evidence and suggestion that perhaps these traits can be passed through to the next generation but if it does occur at all it’s likely to be an exception,” adding that human sperm and egg cells contain robust mechanisms to iron out any environmentally-induced changes in histones. Therefore alterations from external sources such as diet and stress may be very rare, but it is certainly possible.
What is DNA?
DNA stands for Deoxyribonucleic acid and was first identified and isolated by Friedrich Miescher in 1871, and the double helix structure of DNA was first discovered by James Watson and Francis Crick, using experimental data collected by Rosalind Franklin and Maurice Wilkins. Learn about the discovery of DNA here.
DNA is a molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses. DNA is a nucleic acid; alongside proteins and carbohydrates, nucleic acids compose the three major macromolecules essential for all known forms of life. Most DNA molecules consist of two biopolymer strands coiled around each other to form a double helix. The two DNA strands are known as polynucleotides since they are composed of simpler units called nucleotides. The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. Hydrogen bonds bind the nitrogenous bases of the two separate polynucleotide strands to make double-stranded DNA.
As for histones, DNA is extremely long, so fitting it inside a cell requires a lot of packaging. Histones are the first level of packaging that DNA wraps around. Since the DNA needs to be accessible to be transcribed into Ribonucleic acid (RNA), DNA packaging and gene regulation are tightly linked. RNA is similar to DNA; assembled as a chain of nucleotides, but unlike DNA it is more often found in nature as a single-strand folded unto itself, rather than a paired double-strand.