Most molecular genetics experiment cannot be employed on humans because of their complexity. In order to perform these experiments, researchers use certain model organisms which can be cultured very easily in the laboratory and is easy to manipulate. These model organisms though physically different from humans bear certain biochemical and physiological features that have been conserved during evolution (Hedges,2002, p838). With this respect, the nematode worm Caenorhabditis Celegans offer certain exceptional advantages and is one of the foremost model systems in molecular genetics. In order to study gene function in model organisms, single gene mutations are introduced and phenotypical characters are analyzed. The result of this analysis may vary-some of these single gene mutations would produce drastic biochemical or structural differences while others may go silent when compared with the wild-type phenotype (Fire at all,1998). Background of RNAi RNAi (RNA inference) also known as post-transcriptional gene silencing is a biological process which down-regulates expression of the targeted gene. Exogenous dsRNA could induce potent and sequence-specific silencing of endogenous gene expression in C.elegans (Fire et al,1998) i.e. intentional introduction of dsRNA into any organism, the difference in traits as a result of gene silencing may be observed. Worms as a model system: Most molecular genetics experiment cannot be employed on humans because of their complexity. In order to perform these experiments, researchers use certain model organisms which can be cultured very easily in the laboratory and is easy to manipulate and Celegans is an ideal organism because of the following characteristics: It is a eukaryote Genome size is small (97 Megabases) Small lifecycle Easy to maintain in laboratory (Gilbert,2000) Gene that we studied: The entire genome of C.elegans has been sequenced and therefore we have a clear understanding about the genes. We used 4 mutant with different genes suppressed so as to try and understand the role of the genes in the wild C.elegans. The genes are day-10, roll-6, by-1, and unc-22.Material Required: Mutant worms on NGM-lite plates Wild-type worms on NGM-lite plates Binocular dissecting microscope Methods: 1. LAB1-part 1- Plates with wild worms are seen under microscope and behavior is observed. Life stage of microscope and drop on the plate to induce movement. Tapping the plate may also be required to induce movement. Observation of lifecycle is made. 2. LAB1-part 2 Both mutant and wild types are observed under the microscope and morphological and locomotor differences between them are observed and recorded. 2 E. coli are used as the food source for C.elegans. C.elegans are propagated on the lawn of E-coli on NGM-lite medium. The worms are propagated from plate to plate by the process of chucking and picking. Chucking and Picking Chucking is a rapid way of transfer and involved cutting out a portion of the NGM-lite medium where E. coli food source had been consumed and transferring it on a new plate. Picking involves transferring of individual worms with the help of flattened tip of a platinum wire.
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