27 research outputs found
The Infrared Properties of Hickson Compact Groups
Compact groups of galaxies provide a unique environment to study the
mechanisms by which star formation occurs amid continuous gravitational
encounters. We present 2MASS (JHK), Spitzer IRAC (3.5-8 micron) and MIPS (24
micron) observations of a sample of twelve Hickson Compact Groups (HCGs 2, 7,
16, 19, 22, 31, 42, 48, 59, 61, 62, and 90) that includes a total of 45
galaxies. The near-infrared colors of the sample galaxies are largely
consistent with being dominated by slightly reddened normal stellar
populations. Galaxies that have the most significant PAH and/or hot dust
emission (as inferred from excess 8 micron flux) also tend to have larger
amounts of extinction and/or K-band excess and stronger 24 micron emission, all
of which suggest ongoing star formation activity. We separate the twelve HCGs
in our sample into three types based on the ratio of the group HI mass to
dynamical mass. We find evidence that galaxies in the most gas-rich groups tend
to be the most actively star forming. Galaxies in the most gas-poor groups tend
to be tightly clustered around a narrow range in colors consistent with the
integrated light from a normal stellar population. We interpret these trends as
indicating that galaxies in gas-rich groups experience star formation and/or
nuclear actively until their neutral gas consumed, stripped, or ionized. The
galaxies in this sample exhibit a ``gap'' between gas-rich and gas-poor groups
in infrared color space that is sparsely populated and not seen in the Spitzer
First Look Survey sample. This gap may suggest a rapid evolution of galaxy
properties in response to dynamical effects. These results suggest that the
global properties of the groups and the local properties of the galaxies are
connected.Comment: 34 pages, 26 figures, accepted for publication in AJ, higher quality
images available in publicatio
Phylogeny of the Sepia pharaonis species complex (Cephalopoda: Sepiida) based on analyses of mitochondrial and nuclear DNA sequence data
The pharaoh cuttlefish, Sepia pharaonis Ehrenberg, 1831, is a commercially fished species found from
Japan to East Africa. Previous morphological and genetic work (the latter based on the 16S rRNA
mitochondrial gene) suggested that S. pharaonis is a species complex, but relationships within the
complex remained unresolved. To clarify these relationships, we have sequenced an additional mitochondrial
gene region (cytochrome oxidase subunit I) and a nuclear gene region (rhodopsin) from
over 50 specimens from throughout the range of S. pharaonis. We have also added sequence data from
two specimens of Sepia ramani Neethiselvan, 2001, collected in southeastern India. Sepia ramani is a
species that is morphologically very similar to S. pharaonis, and there is some question regarding its
status as a distinct species. Phylogenetic analyses of a dataset comprising all three-gene regions
revealed a monophyletic S. pharaonis complex consisting of a western Indian Ocean clade, a northeastern
Australia clade, a Persian Gulf/Arabian Sea (‘Iranian’) clade, a western Pacific clade and a
central Indian Ocean clade. Relationships among these clades remain somewhat poorly supported
except for a clade comprising the Iranian clade, the western Pacific clade and the central Indian
Ocean clade. One S. pharaonis specimen was collected in the Arabian Sea, but was found to be a
member of the western Indian Ocean clade, suggesting that gene flow between these regions has
either occurred recently or is ongoing. Both specimens of S. ramani are members of the S. pharaonis
complex, but their mtDNA haplotypes are not closely related – one is a member of the central
Indian Ocean clade, while the other is rather distantly related to the northeastern Australia clade.
We suggest that ‘S. pharaonis’ may consist of several species, but morphological work is needed to
clarify species-level taxonomy within this complex
Mid-Infrared Evidence for Accelerated Evolution in Compact Group Galaxies
We find evidence for accelerated evolution in compact group galaxies from the
distribution in mid-infrared colorspace of 42 galaxies from 12 Hickson Compact
Groups (HCGs) compared to the the distributions of several other samples
including the LVL+SINGS galaxies, interacting galaxies, and galaxies from the
Coma Cluster. We find that the HCG galaxies are not uniformly distributed in
colorspace, as well as quantitative evidence for a gap. Galaxies in the infall
region of the Coma cluster also exhibit a non-uniform distribution and a less
well defined gap, which may reflect a similarity with the compact group
environment. Neither the Coma Center or interacting samples show evidence of a
gap, leading us to speculate that the gap is unique to the environment of high
galaxy density where gas has not been fully processed or stripped.Comment: To appear in the Proceedings of the Galaxy Wars: Stellar Populations
and Star Formation in Interacting Galaxies Conferenc
Somatic genome editing with CRISPR/Cas9 generates and corrects a metabolic disease
Germline manipulation using CRISPR/Cas9 genome editing has dramatically accelerated the generation of new mouse models. Nonetheless, many metabolic disease models still depend upon laborious germline targeting, and are further complicated by the need to avoid developmental phenotypes. We sought to address these experimental limitations by generating somatic mutations in the adult liver using CRISPR/Cas9, as a new strategy to model metabolic disorders. As proof-of-principle, we targeted the low-density lipoprotein receptor (Ldlr), which when deleted, leads to severe hypercholesterolemia and atherosclerosis. Here we show that hepatic disruption of Ldlr with AAV-CRISPR results in severe hypercholesterolemia and atherosclerosis. We further demonstrate that co-disruption of Apob, whose germline loss is embryonically lethal, completely prevented disease through compensatory inhibition of hepatic LDL production. This new concept of metabolic disease modeling by somatic genome editing could be applied to many other systemic as well as liver-restricted disorders which are difficult to study by germline manipulation
Hypertension, antihypertensive medication use, and breast cancer risk in the California Teachers Study cohort
A prenylated dsRNA sensor protects against severe COVID-19
Inherited genetic factors can influence the severity of COVID-19, but the molecular explanation underpinning a genetic association is often unclear. Intracellular antiviral defenses can inhibit the replication of viruses and reduce disease severity. To better understand the antiviral defenses relevant to COVID-19, we used interferon-stimulated gene (ISG) expression screening to reveal that OAS1, through RNase L, potently inhibits SARS-CoV-2. We show that a common splice-acceptor SNP (Rs10774671) governs whether people express prenylated OAS1 isoforms that are membrane-associated and sense specific regions of SARS-CoV-2 RNAs, or only express cytosolic, nonprenylated OAS1 that does not efficiently detect SARS-CoV-2. Importantly, in hospitalized patients, expression of prenylated OAS1 was associated with protection from severe COVID-19, suggesting this antiviral defense is a major component of a protective antiviral response
A prenylated dsRNA sensor protects against severe COVID-19
Inherited genetic factors can influence the severity of COVID-19, but the molecular explanation underpinning a genetic association is often unclear. Intracellular antiviral defenses can inhibit the replication of viruses and reduce disease severity. To better understand the antiviral defenses relevant to COVID-19, we used interferon-stimulated gene (ISG) expression screening to reveal that OAS1, through RNase L, potently inhibits SARS-CoV-2. We show that a common splice-acceptor SNP (Rs10774671) governs whether people express prenylated OAS1 isoforms that are membrane-associated and sense specific regions of SARS-CoV-2 RNAs, or only express cytosolic, nonprenylated OAS1 that does not efficiently detect SARS-CoV-2. Importantly, in hospitalized patients, expression of prenylated OAS1 was associated with protection from severe COVID-19, suggesting this antiviral defense is a major component of a protective antiviral response
Analyses Of Deaf1 And Its Role In Deaf1 And Eif4g3 Expression
Deformed epidermal autoregulatory factor-1 (DEAF1) is a transcription factor that has been shown to be essential in development and immunity in Drosophila (Veraksa et al. 2002; Reed et al. 2008) and a contributor to neural tube defects, cancer, and depression in mammals (Hahm et al. 2004; Cubeddu et al. 2006; Iyo et al. 2009). Recently, it has been determined that DEAF1 plays a role in development of peripheral immune tolerance in the lymph nodes, and that variant isoforms and deficiencies of DEAF1 may contribute to development of type I diabetes (Yip et al. 2009). Eukaryotic initiation factor 4 gamma 3 (Eif4g3) has reduced expression in type I diabetics and in Deaf1 deficient mice (Yip et al. 2013). Mouse embryo fibroblasts (MEF) lacking Deaf1 were used as a model system to examine the role of Deaf1 in target gene transcription. Loss of Deaf1 reduced Eif4g3 mRNA levels. DEAF1 was shown to be physically associated with the Deaf1 and Eif4g3 transcriptional promoters. Repressive histone modifications and DNA methylation were absent in Eif4g3 promoter region. These studies indicate that DEAF1 expression positively influences Deaf1 and Eif4g3 transcription by association with the promoters through direct DNA binding and not through changes in DNA or histone modification
Not Available
Not AvailableThe pharaoh cuttlefish, Sepia pharaonis Ehrenberg, 1831, is a commercially fished species found from
Japan to East Africa. Previous morphological and genetic work (the latter based on the 16S rRNA
mitochondrial gene) suggested that S. pharaonis is a species complex, but relationships within the
complex remained unresolved. To clarify these relationships, we have sequenced an additional mitochondrial
gene region (cytochrome oxidase subunit I) and a nuclear gene region (rhodopsin) from
over 50 specimens from throughout the range of S. pharaonis. We have also added sequence data from
two specimens of Sepia ramani Neethiselvan, 2001, collected in southeastern India. Sepia ramani is a
species that is morphologically very similar to S. pharaonis, and there is some question regarding its
status as a distinct species. Phylogenetic analyses of a dataset comprising all three-gene regions
revealed a monophyletic S. pharaonis complex consisting of a western Indian Ocean clade, a northeastern
Australia clade, a Persian Gulf/Arabian Sea (‘Iranian’) clade, a western Pacific clade and a
central Indian Ocean clade. Relationships among these clades remain somewhat poorly supported
except for a clade comprising the Iranian clade, the western Pacific clade and the central Indian
Ocean clade. One S. pharaonis specimen was collected in the Arabian Sea, but was found to be a
member of the western Indian Ocean clade, suggesting that gene flow between these regions has
either occurred recently or is ongoing. Both specimens of S. ramani are members of the S. pharaonis
complex, but their mtDNA haplotypes are not closely related – one is a member of the central
Indian Ocean clade, while the other is rather distantly related to the northeastern Australia clade.
We suggest that ‘S. pharaonis’ may consist of several species, but morphological work is needed to
clarify species-level taxonomy within this complex.Not Availabl