Evidence for Dynamical Changes in a Transitional Protoplanetary Disk with Mid-infrared Variability

We present multi-epoch Spitzer Space Telescope observations of the transitional disk LRLL 31 in the 2-3 Myr-old star forming region IC 348. Our measurements show remarkable mid-infrared variability on timescales as short as one week. The infrared continuum emission exhibits systematic wavelength-dependent changes that suggest corresponding dynamical changes in the inner disk structure and variable shadowing of outer disk material. We propose several possible sources for the structural changes, including a variable accretion rate or a stellar or planetary companion embedded in the disk. Our results indicate that variability studies in the infrared can provide important new constraints on protoplanetary disk behavior.Comment: 15 pages, 4 figures, accepted to ApJ Letter

Identifying Primordial Substructure in NGC 2264

We present new Spitzer Space Telescope observations of the young cluster NGC2264. Observations at 24 micron with the Multiband Imaging Photometer has enabled us to identify the most highly embedded and youngest objects in NGC2264. This letter reports on one particular region of NGC2264 where bright 24 micron sources are spatially configured in curious linear structures with quasi-uniform separations. The majority of these sources (~60% are found to be protostellar in nature with Class I spectral energy distributions. Comparison of their spatial distribution with sub-millimeter data from Wolf-Chase (2003) and millimeter data from Peretto et al. (2005) shows a close correlation between the dust filaments and the linear spatial configurations of the protostars, indicating that star formation is occurring primarily within dense dusty filaments. Finally, the quasi-uniform separations of the protostars are found to be comparable in magnitude to the expected Jeans length suggesting thermal fragmentation of the dense filamentary material.Comment: Accepted for publication in ApJL, 5 pages, 4 figures. Color version available from the following webpages: http://cfa-www.harvard.edu/~pteixeir/ and http://cfa-www.harvard.edu/~clada

A Spitzer Census of Star Formation Activity in the Pipe Nebula

The Pipe Nebula, a large nearby molecular cloud lacks obvious signposts of star formation in all but one of more than 130 dust extinction cores that have been identified within it. In order to quantitatively determine the current level of star formation activity in the Pipe Nebula, we analyzed 13 square degrees of sensitive mid-infrared maps of the entire cloud, obtained with the Multiband Imaging Photometer for Spitzer (MIPS) at wavelengths of 24 micron and 70 micron to search for candidate Young Stellar Objects (YSOs) in the high-extinction regions. We argue that our search is complete for class I and typical class II YSOs with luminosities of Lbol~0.2 Lo and greater. We find only 18 candidate YSOs in the high-extinction regions of the entire Pipe cloud. Twelve of these sources are previously known members of a small cluster associated with Barnard 59, the largest and most massive dense core in the cloud. With only six candidate class I and class II YSOs detected towards extinction cores outside of this cluster, our findings emphatically confirm the notion of an extremely low level of star formation activity in the Pipe Nebula. The resulting star formation efficiency for the entire cloud mass is only ~0.06 %.Comment: 23 pages, 8 figures, accepted for publication in Ap

Generation of cloned transgenic pigs rich in omega-3 fatty acids

Meat products are generally low in omega-3 (n-3) fatty acids, which are beneficial to human health. We describe the generation of cloned pigs that express a humanized Caenorhabditis elegans gene, fat-1, encoding an n-3 fatty acid desaturase. The hfat-1 transgenic pigs produce high levels of n-3 fatty acids from n-6 analogs, and their tissues have a significantly reduced ratio of n-6/n-3 fatty acids (P < 0.001). © 2006 Nature Publishing Group

ISOGAL: A deep survey of the obscured inner Milky Way with ISO at 7 and 15 micron and with DENIS in the near-infrared

The ISOGAL project is an infrared survey of specific regions sampling the Galactic Plane selected to provide information on Galactic structure,stellar populations,stellar mass-loss and the recent star formation history of the inner disk and Bulge of the Galaxy. ISOGAL combines 7 and 15 micron ISOCAM observations - with a resolution of 6'' at worst - with DENIS IJKs data to determine the nature of the sources and theinterstellar extinction. We have observed about 16 square degrees with a sensitivity approaching 10-20mJy, detecting ~10^5 sources,mostly AGB stars,red giants and young stars. The main features of the ISOGAL survey and the observations are summarized in this paper,together with a brief discussion of data processing and quality. The primary ISOGAL products are described briefly (a full description is given in Schuller et al. 2003, astro-ph/0304309): viz. the images and theISOGAL-DENIS five-wavelength point source catalogue. The main scientific results already derived or in progress are summarized. These include astrometrically calibrated 7 and 15um images,determining structures of resolved sources; identification and properties of interstellar dark clouds; quantification of the infrared extinction law and source dereddening; analysis of red giant and (especially) AGB stellar populations in the central Bulge,determining luminosity,presence of circumstellar dust and mass--loss rate,and source classification,supplemented in some cases by ISO/CVF spectroscopy; detection of young stellar objects of diverse types,especially in the inner Bulge with information about the present and recent star formation rate; identification of foreground sources with mid-IR excess. These results are the subject of about 25 refereed papers published or in preparation.Comment: A&A in press. 19 pages,10 Ps figures; problems with figures fixe

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Production of Piglets after Cryopreservation of Embryos Using a Centrifugation-Based Method for Delipation Without Micromanipulation1

It is still difficult to successfully cryopreserve in vitro-produced (IVP) swine embryos, as they are sensitive to chilling due to the abundance of intracellular lipids. Mechanical delipation through micromanipulation is successful, but this method increases the potential of pathogen transmission because of the damage inflicted upon the zona pellucida during micromanipulation, and it is labor intensive. Reported here is a method to remove the lipid of IVP porcine embryos, without significantly compromising the zona pellucida, by trypsin treating the embryos or exposing the embryo to a high-osmolality solution to enlarge the perivitelline space so that the lipid could be polarized and separated completely after subsequent centrifugation without micromanipulation. The procedures work both for nuclear transfer-derived embryos and in vitro-fertilized embryos. Both methods provide a high-throughput process that leaves the zona pellucida intact (or relatively intact for the trypsin treatment) to aid in preventing disease transmission. It is also demonstrated that this procedure results in viable piglets, a claim that could not be made in many previous reports. Although the efficiencies of cryopreservation have not been dramatically improved, these procedures allow a single person to process very large numbers of embryos without the necessity of manipulating each individual embryo on a micromanipulator. Such high-throughput processing overcomes the lack of high efficiency (i.e., the system can be overloaded with embryos for transfer to surrogates)

Significant Improvement in Cloning Efficiency of an Inbred Miniature Pig by Histone Deacetylase Inhibitor Treatment after Somatic Cell Nuclear Transfer1

The National Institutes of Health (NIH) miniature pig was developed specifically for xenotransplantation and has been extensively used as a large-animal model in many other biomedical experiments. However, the cloning efficiency of this pig is very low (<0.2%), and this has been an obstacle to the promising application of these inbred swine genetics for biomedical research. It has been demonstrated that increased histone acetylation in somatic cell nuclear transfer (SCNT) embryos, by applying a histone deacetylase (HDAC) inhibitor such as trichostatin A (TSA), significantly enhances the developmental competence in several species. However, some researchers also reported that TSA treatment had various detrimental effects on the in vitro and in vivo development of the SCNT embryos. Herein, we report that treatment with 500 nM 6-(1,3-dioxo-1H, 3H-benzo[de]isoquinolin-2-yl)-hexanoic acid hydroxyamide (termed scriptaid), a novel HDAC inhibitor, significantly enhanced the development of SCNT embryos to the blastocyst stage when NIH inbred fetal fibroblast cells (FFCs) were used as donors compared with the untreated group (21% vs. 9%, P < 0.05). Scriptaid treatment resulted in eight pregnancies from 10 embryo transfers (ETs) and 14 healthy NIH miniature pigs from eight litters, while no viable piglets (only three mummies) were obtained from nine ETs in the untreated group. Thus, scriptaid dramatically increased the cloning efficiency when using inbred genetics from 0.0% to 1.3%. In contrast, scriptaid treatment decreased the blastocyst rate in in vitro fertilization embryos (from 37% to 26%, P < 0.05). In conclusion, the extremely low cloning efficiency in the NIH miniature pig may be caused by its inbred genetic background and can be improved by alteration of genomic histone acetylation patterns