Chromera et al.: Novel Photosynthetic Alveolates and Apicomplexan Relatives

Linares, Marjorie C.; Carter, Dee; Gould, Sven B.

doi:10.1007/978-3-7091-1303-5_10

Cited by 5 publications

(5 citation statements)

References 40 publications

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“…This suggests that non-cooling thermonuclear bursts are an exclusive feature of high-Ṁ states of NS-LMXBs. The case of T5X2 presented herein, however, remains exceptional for its extremely high burst rate (Linares et al 2011) and for the unprecedented smooth evolution between canonical type I X-ray bursts and non-cooling high-Ṁ bursts. It also opens the prospect of a "hidden", previously unrecognized, population of non-cooling bursts from rapidly accreting NSs.…”

Section: Discussionmentioning

confidence: 85%

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On the Cooling Tails of Thermonuclear X-Ray Bursts: The Igr J17480–2446 Link

Linares

Chakrabarty

Klis

2011

ApJ

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The neutron star transient and 11 Hz X-ray pulsar IGR J17480-2446, recently discovered in the globular cluster Terzan 5, showed unprecedented bursting activity during its 2010 October-November outburst. We analyzed all X-ray bursts detected with the Rossi X-ray Timing Explorer and find strong evidence that they all have a thermonuclear origin, despite the fact that many do not show the canonical spectral softening along the decay imprinted on type I X-ray bursts by the cooling of the neutron star photosphere. We show that the persistent-to-burst power ratio is fully consistent with the accretion-to-thermonuclear efficiency ratio along the whole outburst, as is typical for type I X-ray bursts. The burst energy, peak luminosity and daily-averaged spectral profiles all evolve smoothly throughout the outburst, in parallel with the persistent (non-burst) luminosity. We also find that the peak burst to persistent luminosity ratio determines whether or not cooling is present in the bursts from IGR J17480-2446, and argue that the apparent lack of cooling is due to the "non-cooling" bursts having both a lower peak temperature and a higher non-burst (persistent) emission. We conclude that the detection of cooling along the decay is a sufficient, but not a necessary condition to identify an X-ray burst as thermonuclear. Finally, we compare these findings with X-ray bursts from other rapidly accreting neutron stars.

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Section: Discussionmentioning

confidence: 85%

“…T5X2 is in a 21 hr orbit (Papitto et al 2011) and contains the slowest rotating NS among the type I X-ray burst sources with known spin. Linares et al (2010a) discovered millihertz quasi-periodic oscillations during the peak of the outburst (see also Linares et al 2011).…”

Section: Introductionmentioning

confidence: 99%

On the Cooling Tails of Thermonuclear X-Ray Bursts: The Igr J17480–2446 Link

Linares

Chakrabarty

Klis

2011

ApJ

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“…Chandra quiescent X-ray counterpart searches have now been performed for nine transient cluster LMXBs, of which the three with the faintest outbursts have been identified with very faint (L X < 10 32 ergs/s) quiescent counterparts (M15 X-3, Heinke et al 2009;NGC 6440 X-2, Heinke et al 2010;IGR J17361-4441 in NGC 6388, Pooley et al 2011b), two have spectrally hard counterparts with L X ∼ 10 32−33 ergs/s (EXO 1745-248 in Terzan 5, Wijnands et al 2005;IGR J18245-2452in M28, Papitto et al 2013Linares et al 2013), and four have spectrally soft counterparts with L X ∼ 10 32−33 ergs/s (SAX J1748.9-2021in NGC 6440, in't Zand et al 2001X1732-304 1.1 +1.9 −0.6 -Table 2 Swift/XRT and Chandra/ACIS observations fit to an absorbed power-law model. Unabsorbed flux in units of 10 −12 erg s −1 cm −2 and Luminosity in 10 34 erg s −1 , both in 0.5 -10 keV.…”

Section: Quiescent Counterpartmentioning

confidence: 99%

“…The softening of black hole LMXB spectra has been interpreted as a change in the origin of the X-ray emission, produced at low luminosities by either a radiatively inefficient hot flow (Esin et al 1997;Gardner & Done 2012) or synchrotron emission from a jet (Yuan & Cui 2005;Pszota et al 2008). A similar softening in the spectrum from the accretion flow occurs in NS systems at similar luminosities, where emission from the NS surface can play a role (Armas Padilla et al 2011;Degenaar et al 2013a;Linares et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Discovery of the Third Transient X-Ray Binary in the Galactic Globular Cluster Terzan 5

Bahramian

Heinke

Sivakoff

et al. 2013

ApJ

107

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We report and study the outburst of a new transient X-ray binary (XRB) in Terzan 5, the third detected in this globular cluster, Swift J174805.3-244637 or Terzan 5 X-3. We find clear spectral hardening in Swift/XRT data during the outburst rise to the hard state, thanks to our early coverage (starting at L X ∼ 4 × 10 34 ergs/s) of the outburst. This hardening appears to be due to the decline in relative strength of a soft thermal component from the surface of the neutron star (NS) during the rise. We identify a Type I X-ray burst in Swift/XRT data with a long (16 s) decay time, indicative of hydrogen burning on the surface of the NS. We use Swift/BAT, MAXI/GSC, Chandra/ACIS, and Swift/XRT data to study the spectral changes during the outburst, identifying a clear hard-to-soft state transition. We use a Chandra/ACIS observation during outburst to identify the transient's position. Seven archival Chandra/ACIS observations show evidence for variations in Terzan 5 X-3's non-thermal component, but not the thermal component, during quiescence. The inferred long-term time-averaged mass accretion rate, from the quiescent thermal luminosity, suggests that if this outburst is typical and only slow cooling processes are active in the neutron star core, such outbursts should recur every ∼10 years.11 Note that the true identity of the transient seen by EXOSAT in the 1980s (leading to the EXO name) is not known.

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“…Several investigators have previously pointed out similarities between what we are calling epiplasts/epiplastins present in the euglenids and in the three alveolate radiations ( 21 – 23 , 45 , 46 , 49 , 67 , 90 , 106 , 133 , 139 , 148 ), and Santore ( 124 ) notes similarities between the epiplasts of euglenids and cryptophytes. In this study, we subjected these similarities to comprehensive scrutiny and also analyzed two additional lineages—the glaucophytes and cryptophytes—that had not been previously recognized as epiplastin producers.…”

Section: Discussionmentioning

confidence: 99%

Epiplasts: Membrane Skeletons and Epiplastin Proteins in Euglenids, Glaucophytes, Cryptophytes, Ciliates, Dinoflagellates, and Apicomplexans

Goodenough

Roth

Kariyawasam

et al. 2018

mBio

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Membrane skeletons associate with the inner surface of the plasma membrane to provide support for the fragile lipid bilayer and an elastic framework for the cell itself. Several radiations, including animals, organize such skeletons using actin/spectrin proteins, but four major radiations of eukaryotic unicellular organisms, including disease-causing parasites such as Plasmodium, have been known to construct an alternative and essential skeleton (the epiplast) using a class of proteins that we term epiplastins. We have identified epiplastins in two additional radiations and present images of their epiplasts using electron microscopy. We analyze the sequences and secondary structure of 219 epiplastins and present an in-depth overview and analysis of their known and posited roles in cellular organization and parasite infection. An understanding of epiplast assembly may suggest therapeutic approaches to combat infectious agents such as Plasmodium as well as approaches to the engineering of useful viscoelastic biofilms.

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Chromera et al.: Novel Photosynthetic Alveolates and Apicomplexan Relatives

Cited by 5 publications

References 40 publications

On the Cooling Tails of Thermonuclear X-Ray Bursts: The Igr J17480–2446 Link

On the Cooling Tails of Thermonuclear X-Ray Bursts: The Igr J17480–2446 Link

Discovery of the Third Transient X-Ray Binary in the Galactic Globular Cluster Terzan 5

Epiplasts: Membrane Skeletons and Epiplastin Proteins in Euglenids, Glaucophytes, Cryptophytes, Ciliates, Dinoflagellates, and Apicomplexans

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