Question

Initial probes of the clones have identified partial viral sequences, mainly of genes related to RNA retroviruses that integrate into specific DNA sites on host genomes. A collaborator researches another cichlid,Pundamilia nyereri, thought to be infected by the same virus. She provides the ecologist with tissue samples for investigation. The scientist proceeds to make two libraries: a genomic library and a cDNA library, to compare them and see if a retrovirus does integrate into the genome of the fish gill cells. To calculate how many clones are needed for his genomic library, he obtains the genome size of Pundamilia nyereri from NCBI Genome, which is 830.1 Mb. He uses another enzyme to cut the genomic DNA into 25 kb fragment sizes, and clones them into a EMBL3 vector to generate a recombinant genomic library.

After he has a genomic library, he uses cDNA fragments in a range of 12 kb to 45 kb to generate a cDNA library. The RNA genome of prospective target viruses is in the range of 17 to 20 kb and may be present in low numbers in comparison to the total mRNA at the time of early infection. Estimates average 52 viruses per cell in tissues at the time symptoms first become apparent. Each specialized gill cell is estimated to have approx. 700,000 transcripts of mRNA.

4. How many independent cDNA library clones of the Pundamilia nyereri genome must the ecologist examine to give him a 99.5% probability of finding at least one recombinant containing a cDNA copy of the viral genome? Answer in decimal notation to the nearest whole number.

Answer 1