Clustered regularly interspaced short palindromic repeats cas systems: a comprehensive review.

The clustered regularly interspaced short palindromic repeats (CRISPR) system was recently identified as a bacterial defense mechanism against phages and plasmids. The CRISPR system is composed of DNA arrays containing short sequences identical to those present in phages and plasmids. These short DNAs are transcribed and processed by CRISPR associated proteins that also guide other CRISPR proteins to target the invading DNA. Only a few of the CRISPR components have been characterized to date, and their mechanism of action is still largely unknown. Phage defense mechanisms probably have co-evolved against the CRISPR system, but none has yet been found. We propose to identify phage genes that counteract the CRISPR system.

Short nucleotide sequences signal spliceosomal binding in nucleic acids.

We have explored the region around the splice sites of the human intron and exons from the exon-intron database (EID) and located a number of short 6-nucleotide and 7-nucleotide sequences that are relatively common in the regions. These short sequences, we expect play an important role in the selection of the appropriate splicing process. We propose that the external signals via short recognition sequences play the deterministic role in the actual splicing process. We have obtained 50 such sequences each from the exon and intron from the beginning and from the ending and noted a number of common features.