We report on the discovery of HAT-P-11b, the smallest radius transiting extrasolar planet (TEP) discovered from the ground, and the first hot Neptune discovered to date by transit searches. HAT-P-11b orbits the bright (V=9.587) and metal rich ([Fe/H] = +0.31 ± 0.05) K4 dwarf star GSC 03561-02092 with P = 4.8878162 ± 0.0000071 days and produces a transit signal with depth of 4.2 mmag; the shallowest found by transit searches that is due to a confirmed planet. We present a global analysis of the available photometric and radial-velocity data that result in stellar and planetary parameters, with simultaneous treatment of systematic variations. The planet, like its near-twin GJ 436b, is somewhat larger than Neptune (17M ⊕ , 3.8R ⊕ ) both in mass M p = 0.081 ± 0.009 M J (25.8 ± 2.9 M ⊕ ) and radius R p = 0.422 ± 0.014 R J (4.73 ± 0.16 R ⊕ ). HAT-P-11b orbits in an eccentric orbit with e = 0.198 ± 0.046 and ω = 355.2 ± 17.3 • , causing a reflex motion of its parent star with amplitude 11.6 ± 1.2 m s −1 , a challenging detection due to the high level of chromospheric activity of the parent star. Our ephemeris for the transit events is T c = 2454605.89132 ± 0.00032 (BJD), with duration 0.0957 ± 0.0012 d, and secondary eclipse epoch of 2454608.96 ± 0.15 d (BJD). The basic stellar parameters of the host star are M ⋆ = 0.809 +0.020 −0.027 M ⊙ , R ⋆ = 0.752 ± 0.021 R ⊙ and T eff⋆ = 4780 ± 50 K. Importantly, HAT-P-11 will lie on one of the detectors of the forthcoming Kepler mission; this should make possible fruitful investigations of the detailed physical characteristic of both the planet and its parent star at unprecedented precision. We discuss an interesting constraint on the eccentricity of the system by the transit light curve and stellar parameters. This will be particularly useful for eccentric TEPs with low amplitude RV variations in Kepler's field. We also present a blend analysis, that for the first time treats the case of a blended transiting hot Jupiter mimicing a transiting hot Neptune, and proves that HAT-P-11b is not such a blend.

We report the discovery of HAT-P-16b, a transiting extrasolar planet orbiting the V = 10.8 mag F8 dwarf GSC 2792-01700, with a period P = 2.775960 ± 0.000003 d, transit epoch T c = 2455027.59293 ± 0.00031 (BJD ⋆ ⋆ ⋆ ), and transit duration 0.1276 ± 0.0013 d. The host star has a mass of 1.22 ± 0.04 M ⊙ , radius of 1.24±0.05 R ⊙ , effective temperature 6158±80 K, and metallicity [Fe/H] = +0.17±0.08. The planetary companion has a mass of 4.193 ± 0.094 M J , and radius of 1.289 ± 0.066 R J yielding a mean density of 2.42±0.35 g cm −3 . Comparing these observed characteristics with recent theoretical models, we find that HAT-P-16b is consistent with a 1 Gyr H/He-dominated gas giant planet. HAT-P-16b resides in a sparsely populated region of the mass-radius diagram and has a non-zero eccentricity of e = 0.036 with a significance of 10σ.

We report on the latest discovery of the HATNet project: a very hot giant planet orbiting a bright (V ¼ 10:5) star with a small semimajor axis of a ¼ 0:0377 AE 0:0005 AU. Ephemeris for the system is P ¼ 2:2047299 AE 0:0000040 days, midtransit time E ¼ 2;453;790:2593 AE 0:0010 (BJD). Based on the available spectroscopic data on the host star and photometry of the system, the planet has a mass of M p ¼ 1:78 K. Because the host star is quite bright, measurement of the secondary eclipse should be feasible for ground-based telescopes, providing a good opportunity to compare the predictions of current hot Jupiter atmospheric models with the observations. Moreover, the host star falls in the field of the upcoming Kepler mission; hence extensive space-borne follow-up, including not only primary transit and secondary eclipse observations but also asteroseismology, will be possible.

We report the discovery of a massive ( M p ¼ 9:04 AE 0:50 M J ) planet transiting the bright (V ¼ 8:7) F8 star HD 147506, with an orbital period of 5:63341 AE 0:00013 days and an eccentricity of e ¼ 0:520 AE 0:010. From the transit light curve we determine that the radius of the planet is R p ¼ 0:982 þ0:038 À0:105 R J . HD 147506b (also coined HAT-P-2b) has a mass about 9 times the average mass of previously known transiting exoplanets and a density of p % 12 g cm À3 , greater than that of rocky planets like the Earth. Its mass and radius are marginally consistent with theories of structure of massive giant planets composed of pure H and He, and accounting for them may require a large (k100 M È ) core. The high eccentricity causes a ninefold variation of insolation of the planet between peri-and apastron. Using follow-up photometry, we find that the center of transit is T mid ¼ 2;454;212:8559 AE 0:0007 ( HJD) and the transit duration is 0:177 AE 0:002 days.

The Arabidopsis genome encodes four Dicer-like (DCL) proteins, two of which contain putative nuclear localization signals. This suggests one or more nuclear pathways for processing double-stranded (ds) RNA in plants. To study the subcellular location of processing of nuclear-encoded dsRNA involved in transcriptional silencing, we examined short interfering (si) RNA and micro (mi) RNA accumulation in transgenic Arabidopsis expressing nuclear and cytoplasmic variants of P19, a viral protein that suppresses posttranscriptional gene silencing. P19 binds specifically to DCL-generated 21-to 25-nucleotide (nt) dsRNAs with 2-nt 3Ј overhangs and reportedly suppresses the accumulation of all size classes of siRNA. Nuclear P19 resulted in a significant reduction of 21-to 22-nt siRNAs and a 21-nt miRNA, but had a lesser effect on 24-nt siRNAs. Cytoplasmic P19 did not decrease the quantity but resulted in a 2-nt truncation of siRNAs and miRNA. This suggests that the direct products of DCL cleavage of dsRNA precursors of 21-to 22-nt siRNAs and miRNA are present in the nucleus, where their accumulation is partially repressed, and in the cytoplasm, where both normal sized and truncated forms accumulate. DCL1, which contains two putative nuclear localization signals, is required for miRNA production but not siRNA production. DCL1-green fluorescent protein fusion proteins localize to nuclei in transient expression assays, indicating that DCL1 is a nuclear protein. The results are consistent with a model in which dsRNA precursors of miRNAs and at least some 21-to 22-nt siRNAs are processed in the nucleus, the former by nuclear DCL1 and the latter by an unknown nuclear DCL."RNA silencing" is the suppression of gene expression through nucleotide (nt) sequence-specific interactions that are mediated by RNA (Voinnet, 2002). RNA silencing is triggered by double-stranded (ds) RNA that is processed by an RNase III activity termed Dicer into short RNAs 21 to 25 nt in length (Hannon, 2002;Zamore, 2002). In plants, RNA silencing can act at the posttranscriptional and transcriptional levels (Cerutti, 2003). The 21-to 22-nt short interfering (si) RNAs and micro (mi) RNAs silence genes posttranscriptionally by targeting cognate mRNAs for degradation by an endonuclease complex (Llave et al., 2002a;Tang et al., 2003). A longer class of siRNAs in plants (24-26 nt) has been implicated in directing homologous DNA methylation and in systemic silencing (Hamilton et al., 2002). RNA-directed DNA methylation (RdDM) can lead to transcriptional gene silencing (TGS) if promoter sequences are targeted by homologous RNA (Mette et al., 1999(Mette et al., , 2000Jones et al., 1999Jones et al., , 2001Sijen et al., 2001;Aufsatz et al., 2002aAufsatz et al., , 2002b.The length and functional diversity of short RNAs in plants are reflected in the multiplicity of Dicer-like (DCL) activities. In contrast to genomes of other organisms, which encode one (human, mouse, fission yeast [Schizosaccharomyces pombe], and Caenorhabditis elegans) or two (fruitfly [Drosophila mel...