Why in News
Researchers from Princeton University have reported that after the Caenorhabditis elegans worms ate a disease-causing strain of bacteria, its progeny were born with the ‘knowledge’ to avoid making the same mistake for up to four generations
Pseudomonas vranovensis is a disease-causing bacterium found in C. elegans’s natural environment.
The researchers found that P. vranovensis makes a small RNA molecule called sRNA.
When the worms ingest this strain, they also take in the sRNA.
The sRNA then altered the worm’s feeding behaviour such that, from that point on, the worms ‘know’ to avoid feeding on this bacterium and save themselves from getting sick.
Given the mechanism by which this transmission occurs, the study raises questions about whether humans could have the same ability.
Caenorhabditis elegans
It was the first multicellular organism to have its full genome sequenced and neural wiring mapped.
Caenorhabditis elegans is a free-living transparent nematode that lives in temperate soil environments
C. elegans grows within 3-5 days from a fertilised egg to a millimetre-long adult, and it has informed profound insights into the human body, as well as biology more broadly.
Four chemical bases of DNA and RNA
A DNA molecule is like a big ladder.
Its two side rails, or strands, are made of a long series of alternating units of phosphate and the sugar deoxyribose molecules.
Each sugar unit is attached to one of four chemical bases: adenine (A), cytosine (C), guanine (G), and thymine (T).
The As and Cs on one strand are bonded with Ts and Gs on the other by hydrogen bonds.
These bonds form the rungs that hold the strands together.
In contrast to DNA, the RNA molecule is like a half-ladder or a comb.
Its spine is made up of alternating units of phosphate and the sugar ribose.
Each ribose molecule is attached to one of four bases: A, C, G or uridine (U), which jut out from the strand like the comb’s tines.
A cell copies the sequence of As, Ts, Cs, and Gs in a gene in the DNA into the sequence of Us, As, Gs, and Cs in an RNA molecule.
This RNA is called the messenger (mRNA).
The length of this mRNA is comparable to that of the gene from which it is derived.
The mRNA moves to structures called ribosomes, where the cell assembles the corresponding protein.
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