418 research outputs found
On the triggering of extreme starburst events in low-metallicity galaxies: a deep search for companions of Green Peas
Green pea galaxies are starbursting, low-mass galaxies that are good
analogues to star-forming galaxies in the early universe. We perform a survey
of 23 Green Peas using the MUSE Integral Field Unit spectrograph on the VLT to
search for companion galaxies. The survey reaches an average point-source depth
of erg cm s for emission lines. The MUSE field of
view allows us to probe a 11 arcmin field around these galaxies and
to search their surroundings for faint companions that could have interacted
with them and induced their starburst episodes. We search for companions using
a variety of methods including template matching to emission and absorption
line spectra. When restricting the search to the same physical area (R = 78
kpc) for all galaxies, we find that the fraction of green pea galaxies with
companions is . We define a control sample of
star-forming galaxies with the same stellar masses and redshifts as the green
peas, but consistent with the star-formation main sequence. We find that green
pea galaxies are as likely to have companions as the control sample; for which
the fraction of objects with companions is . Given that
we do not find statistical evidence for an elevated companion fraction in the
green peas in this study, we argue that the ``companions" are likely unrelated
to the bursts in these galaxies.Comment: Accepted for publication in the Astrophysical Journa
Cloning and characterization of the Schizosaccharomyces pombe homologs of the human protein Translin and the Translin-associated protein TRAX
Translin is a human octameric protein that specifically binds the single-stranded microsatellite repeats d(GT)(n) and the corresponding transcripts (GU)(n). It also binds, with lesser affinities, other single-stranded G-rich DNA and RNA sequences. TRAX is a human protein that bears a homology to Translin and interacts with it. Translin and TRAX have been proposed to be involved in DNA recombination, chromosomal translocation and mRNA transport and translation. Both proteins are highly conserved in eukaryotes, including the fission yeast Schizosaccharomyces pombe, which is amenable to genetic analysis. Here, we report the first study of the S.pombe Translin and TRAX homologs. We have deleted the genes encoding Translin and TRAX in S.pombe and found that the proliferation of the mutant cells was slightly stimulated, suggesting that these genes are not essential for the fission yeast. We have also shown that the S.pombe Translin and TRAX interact. Biochemical analysis of the S.pombe Translin, which was cloned and expressed in Escherichia coli, revealed that it is octameric and that it selectively binds d(GT)(n) and d(GTT)(n) microsatellite repeats. However, unlike the human protein, it has much higher affinities for the homologous RNA sequences (GU)(n) and (GUU)(n). These data suggest that the S.pombe Translin is primarily involved in functions related to RNA metabolism
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