SIRT1 Regulates HIV Transcription via Tat Deacetylation

The human immunodeficiency virus (HIV) Tat protein is acetylated by the transcriptional coactivator p300, a necessary step in Tat-mediated transactivation. We report here that Tat is deacetylated by human sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide-dependent class III protein deacetylase in vitro and in vivo. Tat and SIRT1 coimmunoprecipitate and synergistically activate the HIV promoter. Conversely, knockdown of SIRT1 via small interfering RNAs or treatment with a novel small molecule inhibitor of the SIRT1 deacetylase activity inhibit Tat-mediated transactivation of the HIV long terminal repeat. Tat transactivation is defective in SIRT1-null mouse embryonic fibroblasts and can be rescued by expression of SIRT1. These results support a model in which cycles of Tat acetylation and deacetylation regulate HIV transcription. SIRT1 recycles Tat to its unacetylated form and acts as a transcriptional coactivator during Tat transactivation

Stratospheric aerosol - Observations, processes, and impact on climate

Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20% cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfate matter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes

The looming split on the Right. by Brian Toohey

While the government's economic statement revealed a new, interventionist strategy for recovery, the opposition seems wedded to the level playing field. But there's a growing divergence of opinion among conservatives

Warren's Indon mates. by Brian Toohey

Warren Anderson is a lucky man. First he has the privilege of being a close personal friend of the Treasurer. Second, when other property developers are going to the wall, he has managed to find some Indonesians wealthy enough to pay a spectacular price for a half share in his cattle properties

Julie Bishop was (half) right

It\u27s time to drop he convention that neither side of politics comments on intelligence agencies, writes Brian Toohey in Inside StoryMEMBERS of Australia’s intelligence organisations are public servants. If they break the law, endanger the lives of fellow Australians or otherwise stuff-up, it should be a matter for public discussion. From this perspective, the shadow foreign minister, Julie Bishop, did the nation a service during an interview on 25 May when she revealed that Australian officials had forged Australian passports for security operations. Although this was not Bishop’s point, the practice is illegal and potentially dangerous for innocent passport holders. Yet many journalists, security “experts” and senior ministers reacted as if Bishop had machine-gunned a pack of girl guides laying a wreath on a memorial to Simpson and his donkey. Bishop gave the offending interview soon after she received a government briefing on why it had expelled a member of the Israeli intelligence service, Mossad, after concluding that Israel fraudulently used Australian passports during an operation to assassinate a senior Hamas member in Dubai. Although the foreign minister, Stephen Smith, denied that Bishop had revealed what she had been told in briefings, some journalists and commentators presumed she had blurted out information she’d received confidentially. But most of the fury was directed at Bishop for breaching what Kevin Rudd called a longstanding convention that... Read the full article Photo: bigmick/ Flick

Big cuts and little cuts

It’s not so much the size of government spending that counts - it’s the quality, writes Brian Toohey in Inside Story FOLLOWING the brief excitement of the global financial crisis, Australian politics is back in a familiar groove. A Labor government is trying to demonstrate its commitment to fiscal discipline by imposing yet another “efficiency dividend” on the public service. The latest example to attract the public limelight was a plan to close the National Archives offices in Adelaide, Hobart and Darwin, saving $1.4 million a year out of annual government spending of around$345 billion. Faced with public opposition, the government last week decided to retain an archival presence in each city, but co-locate them with the offices of similar bodies such as state public records. It isn’t clear how much, if anything, will now be saved. Meanwhile, the Coalition is lambasting Labor for its alleged addiction to “big spending” and “spiralling debt,” while blocking its attempt to save money by means testing the rebate on private (or, more accurately, semi-private) health insurance. Never mind that John Howard’s Coalition government was no slouch on the spending front (see Treasury’s Economic Round Up, Summer 2008). Likewise, since becoming Coalition leader in December, Tony Abbott has announced over $6 billion in spending initiatives without accompanying funding measures... Read the full article Photo: Andrew Jeffre