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  • 1
    Publication Date: 2013-02-28
    Description: This paper presents new observations of the planet-hosting, visual binary GJ 86 (HR 637) using the Hubble Space Telescope . Ultraviolet and optical imaging with WFC3 confirms the stellar companion is a degenerate star and indicates the binary semimajor axis is larger than previous estimates, with a 28 au. Optical STIS spectroscopy of the secondary reveals a helium-rich white dwarf with C 2 absorption bands and T eff  = 8180 K, thus making the binary system rather similar to Procyon. Based on the 10.8 pc distance, the companion has 0.59 M and descended from a main-sequence A star of 1.9 M with an original orbital separation a 14 au. If the giant planet is coplanar with the binary, the mass of GJ 86Ab is between 4.4 and 4.7 M Jup . The similarity of GJ 86 and Procyon prompted a re-analysis of the white dwarf in the latter system, with the tentative conclusion that Procyon hosts a planetesimal population. The periastron distance in Procyon is 20 per cent smaller than in α Cen AB, but the metal-enriched atmosphere of Procyon B indicates that the planet formation process minimally attained 25 km bodies, if not small planets as in α Cen.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 2
    Publication Date: 2013-10-08
    Description: Approximately 70 per cent of the nearby white dwarfs appear to be single stars, with the remainder being members of binary or multiple star systems. The most numerous and most easily identifiable systems are those in which the main-sequence companion is an M star, since even if the systems are unresolved the white dwarf either dominates or is at least competitive with the luminosity of the companion at optical wavelengths. Harder to identify are systems where the non-degenerate component has a spectral type earlier than M0 and the white dwarf becomes the less luminous component. Taking Sirius as the prototype, these latter systems are referred to here as ‘Sirius like’. There are currently 98 known Sirius-like systems. Studies of the local white dwarf population within 20 pc indicate that approximately 8 per cent of all white dwarfs are members of Sirius-like systems, yet beyond 20 pc the frequency of known Sirius-like systems declines to between 1 and 2 per cent, indicating that many more of these systems remain to be found. Estimates are provided for the local space density of Sirius-like systems and their relative frequency among both the local white dwarf population and the local population of A to K main-sequence stars. The great majority of currently unidentified Sirius-like systems will likely turn out to be closely separated and unresolved binaries. Ways to observationally detect and study these systems are discussed.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 3
    Publication Date: 2014-10-17
    Description: We present high time resolution SDSS- g ' and SDSS- z ' light curves of the primary eclipse in SDSS J141126.20+200911.1, together with time-resolved X-Shooter spectroscopy and near-infrared (NIR) JHK s photometry. Our observations confirm the substellar nature of the companion, making SDSS J141126.20+200911.1 the first eclipsing white dwarf/brown dwarf binary known. We measure a (white dwarf model dependent) mass and radius for the brown dwarf companion of M 2  = 0.050 ± 0.002 M and R 2  = 0.072 ± 0.004 M , respectively. The lack of a robust detection of the companion light in the z ' -band eclipse constrains the spectral type of the companion to be later than L5. Comparing the NIR photometry to the expected white dwarf flux reveals a clear K s -band excess, suggesting a spectral type in the range L7–T1. The radius measurement is consistent with the predictions of evolutionary models, and suggests a system age in excess of 3 Gyr. The low companion mass is inconsistent with the inferred spectral type of L7–T1, instead predicting a spectral type nearer T5. This indicates that irradiation of the companion in SDSS J141126.20+200911.1 could be causing a significant temperature increase, at least on one hemisphere.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 4
    Publication Date: 2009-10-09
    Description: Recent advances in next generation sequencing have made it possible to precisely characterize all somatic coding mutations that occur during the development and progression of individual cancers. Here we used these approaches to sequence the genomes (〉43-fold coverage) and transcriptomes of an oestrogen-receptor-alpha-positive metastatic lobular breast cancer at depth. We found 32 somatic non-synonymous coding mutations present in the metastasis, and measured the frequency of these somatic mutations in DNA from the primary tumour of the same patient, which arose 9 years earlier. Five of the 32 mutations (in ABCB11, HAUS3, SLC24A4, SNX4 and PALB2) were prevalent in the DNA of the primary tumour removed at diagnosis 9 years earlier, six (in KIF1C, USP28, MYH8, MORC1, KIAA1468 and RNASEH2A) were present at lower frequencies (1-13%), 19 were not detected in the primary tumour, and two were undetermined. The combined analysis of genome and transcriptome data revealed two new RNA-editing events that recode the amino acid sequence of SRP9 and COG3. Taken together, our data show that single nucleotide mutational heterogeneity can be a property of low or intermediate grade primary breast cancers and that significant evolution can occur with disease progression.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shah, Sohrab P -- Morin, Ryan D -- Khattra, Jaswinder -- Prentice, Leah -- Pugh, Trevor -- Burleigh, Angela -- Delaney, Allen -- Gelmon, Karen -- Guliany, Ryan -- Senz, Janine -- Steidl, Christian -- Holt, Robert A -- Jones, Steven -- Sun, Mark -- Leung, Gillian -- Moore, Richard -- Severson, Tesa -- Taylor, Greg A -- Teschendorff, Andrew E -- Tse, Kane -- Turashvili, Gulisa -- Varhol, Richard -- Warren, Rene L -- Watson, Peter -- Zhao, Yongjun -- Caldas, Carlos -- Huntsman, David -- Hirst, Martin -- Marra, Marco A -- Aparicio, Samuel -- England -- Nature. 2009 Oct 8;461(7265):809-13. doi: 10.1038/nature08489.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Molecular Oncology, BC Cancer Agency, 675 West 10th Avenue, Vancouver V5Z 1L3, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19812674" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptor Proteins, Vesicular Transport/genetics ; Breast Neoplasms/*genetics/metabolism/*pathology ; DNA Mutational Analysis ; Disease Progression ; Estrogen Receptor alpha/metabolism ; Evolution, Molecular ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic ; Genes, Neoplasm/*genetics ; Genome, Human/genetics ; Germ-Line Mutation/genetics ; Humans ; Mutagenesis/*genetics ; Mutation/*genetics ; Neoplasm Metastasis ; Nucleotides/*genetics ; RNA Editing/genetics ; Signal Recognition Particle/genetics ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2012-04-13
    Description: Primary triple-negative breast cancers (TNBCs), a tumour type defined by lack of oestrogen receptor, progesterone receptor and ERBB2 gene amplification, represent approximately 16% of all breast cancers. Here we show in 104 TNBC cases that at the time of diagnosis these cancers exhibit a wide and continuous spectrum of genomic evolution, with some having only a handful of coding somatic aberrations in a few pathways, whereas others contain hundreds of coding somatic mutations. High-throughput RNA sequencing (RNA-seq) revealed that only approximately 36% of mutations are expressed. Using deep re-sequencing measurements of allelic abundance for 2,414 somatic mutations, we determine for the first time-to our knowledge-in an epithelial tumour subtype, the relative abundance of clonal frequencies among cases representative of the population. We show that TNBCs vary widely in their clonal frequencies at the time of diagnosis, with the basal subtype of TNBC showing more variation than non-basal TNBC. Although p53 (also known as TP53), PIK3CA and PTEN somatic mutations seem to be clonally dominant compared to other genes, in some tumours their clonal frequencies are incompatible with founder status. Mutations in cytoskeletal, cell shape and motility proteins occurred at lower clonal frequencies, suggesting that they occurred later during tumour progression. Taken together, our results show that understanding the biology and therapeutic responses of patients with TNBC will require the determination of individual tumour clonal genotypes.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3863681/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3863681/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shah, Sohrab P -- Roth, Andrew -- Goya, Rodrigo -- Oloumi, Arusha -- Ha, Gavin -- Zhao, Yongjun -- Turashvili, Gulisa -- Ding, Jiarui -- Tse, Kane -- Haffari, Gholamreza -- Bashashati, Ali -- Prentice, Leah M -- Khattra, Jaswinder -- Burleigh, Angela -- Yap, Damian -- Bernard, Virginie -- McPherson, Andrew -- Shumansky, Karey -- Crisan, Anamaria -- Giuliany, Ryan -- Heravi-Moussavi, Alireza -- Rosner, Jamie -- Lai, Daniel -- Birol, Inanc -- Varhol, Richard -- Tam, Angela -- Dhalla, Noreen -- Zeng, Thomas -- Ma, Kevin -- Chan, Simon K -- Griffith, Malachi -- Moradian, Annie -- Cheng, S-W Grace -- Morin, Gregg B -- Watson, Peter -- Gelmon, Karen -- Chia, Stephen -- Chin, Suet-Feung -- Curtis, Christina -- Rueda, Oscar M -- Pharoah, Paul D -- Damaraju, Sambasivarao -- Mackey, John -- Hoon, Kelly -- Harkins, Timothy -- Tadigotla, Vasisht -- Sigaroudinia, Mahvash -- Gascard, Philippe -- Tlsty, Thea -- Costello, Joseph F -- Meyer, Irmtraud M -- Eaves, Connie J -- Wasserman, Wyeth W -- Jones, Steven -- Huntsman, David -- Hirst, Martin -- Caldas, Carlos -- Marra, Marco A -- Aparicio, Samuel -- 5U01ES017154-02/ES/NIEHS NIH HHS/ -- R01 GM084875/GM/NIGMS NIH HHS/ -- R01GM084875/GM/NIGMS NIH HHS/ -- Cancer Research UK/United Kingdom -- England -- Nature. 2012 Apr 4;486(7403):395-9. doi: 10.1038/nature10933.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia V6T 2B5, Canada. sshah@bccrc.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22495314" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Breast Neoplasms/diagnosis/*genetics/*pathology ; Clone Cells/metabolism/pathology ; DNA Copy Number Variations/genetics ; DNA Mutational Analysis ; Disease Progression ; *Evolution, Molecular ; Female ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic/genetics ; Genotype ; High-Throughput Nucleotide Sequencing ; Humans ; INDEL Mutation/genetics ; Mutation/*genetics ; Point Mutation/genetics ; Precision Medicine ; Reproducibility of Results ; Sequence Analysis, RNA
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2013-07-04
    Description: A surprisingly large fraction (70 per cent) of hot, carbon-dominated atmosphere (DQ) white dwarfs are magnetic and/or photometrically variable on short time-scales up to ~1000 s. However, here, we show that the hot DQ magnetic white dwarf SDSS J000555.90–100213.5 is photometrically variable by 11 per cent on a longer time-scale, with a period of 2.110 ± 0.045 d. We find no evidence of the target fluctuating on short time-scales at an amplitude of ±0.5 per cent. Short period hot DQ white dwarfs have been interpreted as non-radial pulsators, but in the case of SDSS J0005–1002, it is more likely that the variability is due to the rotation of the magnetic hot DQ white dwarf. We suggest that some hot DQ white dwarfs, varying on short time-scales, should be more carefully examined to ascertain whether the variability is due to rotation rather than pulsation. All hot DQs should be monitored for long-period modulations as an indicator of rotation and magnetism.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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