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Evidence for several waves of global transmission in the seventh cholera pandemic
Mutreja, Ankur,Kim, Dong Wook,Thomson, Nicholas R.,Connor, Thomas R.,Lee, Je Hee,Kariuki, Samuel,Croucher, Nicholas J.,Choi, Seon Young,Harris, Simon R.,Lebens, Michael,Niyogi, Swapan Kumar,Kim, Eun J Nature Publishing Group, a division of Macmillan P 2011 Nature Vol.477 No.7365
Vibrio cholerae is a globally important pathogen that is endemic in many areas of the world and causes 3??5??million reported cases of cholera every year. Historically, there have been seven acknowledged cholera pandemics; recent outbreaks in Zimbabwe and Haiti are included in the seventh and ongoing pandemic. Only isolates in serogroup O1 (consisting of two biotypes known as ??classical?? and ??El Tor??) and the derivative O139 (refs 2, 3) can cause epidemic cholera. It is believed that the first six cholera pandemics were caused by the classical biotype, but El Tor has subsequently spread globally and replaced the classical biotype in the current pandemic. Detailed molecular epidemiological mapping of cholera has been compromised by a reliance on sub-genomic regions such as mobile elements to infer relationships, making El Tor isolates associated with the seventh pandemic seem superficially diverse. To understand the underlying phylogeny of the lineage responsible for the current pandemic, we identified high-resolution markers (single nucleotide polymorphisms; SNPs) in 154 whole-genome sequences of globally and temporally representative V.??cholerae isolates. Using this phylogeny, we show here that the seventh pandemic has spread from the Bay of Bengal in at least three independent but overlapping waves with a common ancestor in the 1950s, and identify several transcontinental transmission events. Additionally, we show how the acquisition of the SXT family of antibiotic resistance elements has shaped pandemic spread, and show that this family was first acquired at least ten years before its discovery in V.??cholerae.
GLOBULAR AND OPEN CLUSTERS OBSERVED BY SDSS/SEGUE: THE GIANT STARS
Morrison, Heather L.,Ma, Zhibo,Clem, James L.,An, Deokkeun,Connor, Thomas,Schechtman-Rook, Andrew,Casagrande, Luca,Rockosi, Constance,Yanny, Brian,Harding, Paul,Beers, Timothy C.,Johnson, Jennifer A. American Astronomical Society 2016 The Astronomical journal Vol.151 No.1
<P>We present griz observations for the clusters M92, M13 and NGC 6791 and gr photometry for M71, Be 29 and NGC 7789. In addition we present new membership identifications for all these clusters, which have been observed spectroscopically as calibrators for the Sloan Digital Sky Survey (SDSS)/SEGUE survey; this paper focuses in particular on the red giant branch stars in the clusters. In a number of cases, these giants were too bright to be observed in the normal SDSS survey operations, and we describe the procedure used to obtain spectra for these stars. For M71, we also present a new variable reddening map and a new fiducial for the gr giant branch. For NGC 7789, we derived a transformation from T-eff to g-r for giants of near solar abundance, using IRFM T-eff measures of stars with good ugriz. and 2MASS photometry and SEGUE spectra. The result of our analysis is a robust list of known cluster members with correctly dereddened and (if needed) transformed gr photometry for crucial calibration efforts for SDSS and SEGUE.</P>