The fruit fly, Drosophila melanogaster has been an influential invertebrate model organism in understanding gene function for over a century. In addition to being suitable for classical genetics, its adaptability to evolving gene modification tools ranging from transgenesis to novel genome modification tools including CRISPR has made the fly a sought after model organism in modern biology. Over the past six years the Fly Facility, has provided services to facilitate modern molecular genetics in Drosophila.
a. P-element mediated transgenesis
P-element Classic - Injection of DNA into the embryos, raising the survived larvae to adulthood and crossing the G0 flies (>100 individual crosses). Identification and collection of transformants; the collected transformant flies (at least 3 independent lines) are sent to the customer and original vials are maintained in the facility for two weeks as backup.
P-element Excel - This involves mapping the insertions of the screened transgenic lines followed by the Classic service and balancing the insertions.
b. PhiC31integrase mediated transgenesis:
Site-Specific Excel - Injection of DNA into the embryos of PhiC31 integrase & selected attP docking site (click here and choose attP sites), crossing of G0 flies, screening the transformants and balancing the insertions.
Site-Specific BAC- This service includes injecting the BACs or fosmids (>30kb) into 500 embryos of strain (or a cross of) PhiC31-integrase and a docking site of the user’s choice and scoring the transformants, balancing and shipping.
Site-Specific CRISPR- This service includes injecting the plasmids with CRISPR/Cas9 guide RNA into 300 embryos of strain (or a cross of) PhiC31-integrase and a docking site of the user’s choice and scoring the transformants, balancing and shipping.
The fly facility has started using CRISPR-Cas9 system to generate deletions. The use of the CRISPR-Cas9 nuclease system is a very young but rapidly developing area of modern biology. The type II CRISPR system from S. pyogenes has been adapted for inducing sequence-specific DSBs and targeted genome editing. In this system, Cas9 endonuclease and a target sequence specific guide RNA (gRNA) are introduced into a heterologous system to generate DSBs in their genome in a sequence specific manner, making it a useful genetic engineering tool to induce deletions, insertions, and precisely defined modifications in genomes of diverse organisms.
This technique has been used in Drosophila to mutate about a dozen genes and different methods to improve efficiency are being actively under research. Our facility is providing the service of sgRNA injections in various fly backgrounds in addition to full genomic deletion service. Please write to us for further details.