Cooperative roles of introns 1 and 2 of tobacco resistance gene N in enhanced N transcript expression and antiviral defense responses.

The tobacco virus resistance gene N contains four introns. Transient expression of transcripts from an N transgene containing these introns and driven by the native promoter in the presence of the elicitor of tobacco mosaic virus resulted in its increased expression. The requirement of the native promoter, the elicitor, or the individual introns for enhanced expression of N has not been fully studied. Here, we determined that 35S promoter-driven N transcript expression could be enhanced in the presence of the four introns regardless of the co-expression of the virus elicitor in tobacco. Function analyses using a series of N transgenes with different combination of introns revealed that the presence of intron 1 more so than intron 2 allowed higher accumulation of premature and mature N transcripts; however, both introns were important for not only enhanced gene expression but also for induction of cell death in tobacco and induced local resistance to spread of virus in Nicotiana benthamiana. Our findings indicate that introns 1 and 2 cooperatively contribute to N expression and virus resistance.

[Re-operation of an aortic pericardial bioprosthesis 23-years after implantation; report of a case].

A 49-year-old female suffered from dyspnea on exertion and jaundice from June, 2009. She had undergone aortic valve replacement with Carpentier-Edwards pericardial bioprosthesis due to active infectious endocarditis 23-years previously. The echocardiography showed severe aortic stenosis with moderate regurgitation. She was diagnosed as having prosthetic valve malfunction. Re-replacement of the aortic valve with mechanical valve was successfully performed. As far as we can see, this is one of the longest-term cases of implantation of pericardial bioprosthesis.