Genetic manipulation of Prochlorococcus strain MIT9313: green fluorescent protein expression from an RSF1010 plasmid and Tn5 transposition.

Prochlorococcus is the smallest oxygenic phototroph yet described. It numerically dominates the phytoplankton community in the mid-latitude oceanic gyres, where it has an important role in the global carbon cycle. The complete genomes of several Prochlorococcus strains have been sequenced, revealing that nearly half of the genes in each genome are of unknown function.

Mammalian Sir2 homolog SIRT7 is an activator of RNA polymerase I transcription.

We investigated the role of SIRT7, one of the seven members of the mammalian sirtuin family. We show that SIRT7 is a widely expressed nucleolar protein that is associated with active rRNA genes (rDNA), where it interacts with RNA polymerase I (Pol I) as well as with histones. Overexpression of SIRT7 increases Pol I-mediated transcription, whereas knockdown of SIRT7 or inhibition of the catalytic activity results in decreased association of Pol I with rDNA and a reduction of Pol I transcription.

Spindle checkpoint maintenance requires Ame1 and Okp1.

Kinetochore proteins are required for high fidelity chromosome segregation and as a platform for checkpoint signaling. Ame1 is an essential component of the COMA (Ctf19, Okp1, Mcm21, Ame1) sub-complex of the central kinetochore of budding yeast. In this study, we describe the isolation and characterization of an Ame1 conditional mutant, ame1-4.

Mouse Sir2 homolog SIRT6 is a nuclear ADP-ribosyltransferase.

Members of the Sir2 family of NAD-dependent protein deacetylases regulate diverse cellular processes including aging, gene silencing, and cellular differentiation. Here, we report that the distant mammalian Sir2 homolog SIRT6 is a broadly expressed, predominantly nuclear protein. Northern analysis of embryonic samples and multiple adult tissues revealed mouse SIRT6 (mSIRT6) mRNA peaks at day E11, persisting into adulthood in all eight tissues examined.

Saccharomyces cerevisiae SSD1-V confers longevity by a Sir2p-independent mechanism.

The SSD1 gene of Saccharomyces cerevisiae is a polymorphic locus that affects diverse cellular processes including cell integrity, cell cycle progression, and growth at high temperature. We show here that the SSD1-V allele is necessary for cells to achieve extremely long life span. Furthermore, addition of SSD1-V to cells can increase longevity independently of SIR2, although SIR2 is necessary for SSD1-V cells to attain maximal life span.