Constraints on cosmological models from Hubble parameters measurements

In this paper, we study the cosmological constraints from the measurements of Hubble parameters — H(z) data. Here, we consider two kinds of H(z) data: the direct H0 probe from the Hubble Space Telescope (HST) observations of Cepheid variables with H0 = 73.8 ± 2.4 km s-1 Mpc-1 and several measurements on the Hubble parameter at high redshifts H(z). Employing Markov Chain Monte Carlo (MCMC) method, we also combine the WMAP nine-year data (WMAP9), the baryon acoustic oscillations (BAO) and type Ia supernovae (SNIa) Union2.1 compilation to determine the cosmological parameters, such as the equation of state (EoS) of dark energy w, the curvature of the universe Ωk, the total neutrino mass ∑mν, the effective number of neutrinos N eff and the parameters associated with the power spectrum of primordial fluctuations. These H(z) data provide extra information on the accelerate rate of our universe at high redshifts. Therefore, adding these H(z) data significantly improves the constraints on cosmological parameters, such as the number of relativistic species. Moreover, we find that direct prior on H0 from HST can also give good constraints on some parameters, due to the degeneracies between these parameters and H0.

Transactivation activity of the human cytomegalovirus IE2 protein occurs at steps subsequent to TATA box-binding protein recruitment

The IE2 protein of human cytomegalovirus transactivates viral and cellular promoters through a wide variety of cis-elements, but the mechanism of its action has not been well characterized. Here, IE2–Sp1 synergy and IE2–TATA box-binding protein (TBP) interaction are examined by artificial recruitment of either Sp1 or TBP to the promoter. It was found that IE2 could cooperate with DNA-bound Sp1. A 117 amino acid glutamine-rich fragment of Sp1, which can interact with Drosophila TAFII110 and human TAFII130, was sufficient for the augmentation of IE2-driven transactivation. In binding assays in vitro, IE2 interacted directly with the C-terminal region of Sp1, which contains the zinc finger DNA-binding domain, but not with its transactivation domain, suggesting that synergy between IE2 and the transactivation domain of Sp1 might be mediated by other proteins such as TAF or TBP. It was also found that TBP recruitment to the promoter markedly increased IE2-mediated transactivation. Thus, IE2 acts synergistically with DNA-bound Sp1 and DNA-bound TBP. These results suggest that, in human cytomegalovirus IE2 transactivation, Sp1 functions at an early step such as recruitment of TBP and IE2 acts to accelerate rate-limiting steps after TBP recruitment.