Gene Silencing

Gene Silencing

Gene silencing or RNA interference (RNAi) is a biological occurring mechanism in higher eukaryotes by which gene expression is regulated by short double-stranded RNA sequences. The mechanism occurs after the gene has been transcribed , and it was initially considered a phenomenon limited to petunias and a few other plant species, recently it has become clear that post transcription gene silencing occurs in both plants and animals and has roles in viral defence and transposon silencing mechanisms. Perhaps most exciting phenomenon and one of the hottest topics in molecular biology today is the use of RNA interference (RNAi) by introducing double-stranded RNA (dsRNA) as a tool to knock down expression of specific genes in a variety of organisms. In 1998, Andrew Fire and Craig Mello published a break-through study in the mechanism of RNA interference and they established that, only injection of double-stranded RNA (dsRNA) into C.elegan led to an efficient loss of the target mRNA. Following this break-through, researchers are no longer restricted to classical forward genetic screening where the gene can only be studied by inducing mutation then sorting of the phenotype of interest instead, gene silencing provide an alternative approach known as “Reverse genetics” where the functional study of a gene starts with the gene sequencing rather than mutant phenotype. Using reverse genetics one can investigate the function of all genes in a gene family, one can study the function of a gene found to be involved in a process of interest in another organism, something not easily done with forward genetics.

Cryopreservation- the wonder of modern science

One of the most amazing inventions of the 19th century is cryopreservation which is the process of preserving living cells or tissues in an extremely low temperature usually -196 degree centigrade which is achieved by using liquid nitrogen. The principle of cryopreservation is that during the process water inside and outside the cells are converted to ice, and as a result the metabolic and physical processes stop but there is always risks of damage to the cells which can be overcome by using cryoprotectants, chemicals which effectively reduce the damage to the cells during ice formation and whenever the cells need to be revived, they are thawed by increasing temperatures. The process involves the cells or tissues to be mixed with cryoprotectants in a styrofoam tube or glass tube and introduced in a special deep freezer which cool down the tubes up to -80 degree centigrade at the cooling rate of 1 degree centigrade per minute and then subsequent transferring to liquid nitrogen. A variety of cells and tissues including semen, stem cells, oocytes, embryos from animals and pollen, seeds, cells in tissue culture from plants have been successfully preserved by this technique. Ethical and commercial applications of this technique include genetic diversity preservation, stem cell culture to cure cancer patients and sperm banking. Cryopreservation continues to explore new doors to the advanced research and scientists are now working to preserve the human body for indefinite period and one day the dream to conquest death may come true.

Mohammad Mamun Chowdhury,EUMAINE