Transcriptional Analysis of Bm-1 Repetitive Elements in the genome of Bombvx mori

Document Type



Master of Science (MS)



First Advisor's Name

Rene J. Herrera

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Case K. Ockubo

Third Advisor's Name

Martin L. Tracey

Date of Defense



Bm-1 repetitive element family represents a group of sequences in the genome of the silkmoth, Bombyx mori. and is found to be transcribed. There are about 3X more Bm-1 cytoplasmic transcripts as compared to their nuclear counterparts. The size range of Bm-1 nuclear transcripts is greater than that of their cytoplasmic species. Alpha- amanitin inhibition and nuclear ”run-on” experiments demonstrated that 80-85% of the Bm-1 transcripts are produced by RNA polymerase II; the other 15-20% may be transcribed by polymerase I and/or III. Sharply contrasting with most of the transcribed SINE families, the Bm-1 transcripts are dramatically enriched in both poly A+ and polysomal RNA fractions. Compared to Bm-1 transcripts in total RNA there are 2-4X more Bm-1 transcripts in the poly A+ RNA population and up to 22X more in the polysomal RNA fractions. This strongly suggests that the transcripts of the Bm-1 family may be involved in translation. To express exogenous Bm-1 elements in vivo and explore their effect(s) on transcriptional actitivity in Bombyx mori cells in culture and their possible function in gene regulation, two members of the Bm-1 family, clone 1 and clone 10, have been subcloned into a selectable and inducible plasmid vector and were named as pG/1 and pG/10, respectively. Subsequently, they were introduced into the BmN and Bm-5 Bombyx mori cell lines by electro-transfection. A G418 (Geneticin) resistant Bombyx mori cell population has been selected out, following transfection.



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