197 research outputs found
Extended Ultraviolet Disks and Ultraviolet-bright Disks in Low-mass E/S0 Galaxies
We have identified 15 extended ultraviolet (XUV) disks in a largely field sample of 38 E/S0 galaxies that have stellar masses primarily below ~4 × 10^(10) M_☉ and comparable numbers on the red and blue sequences. We use a new purely quantitative XUV-disk definition designed with reference to the "Type 1" XUV-disk definition found in the literature, requiring UV extension relative to a UV-defined star formation threshold radius. The 39% ± 9% XUV-disk frequency for these E/S0s is roughly twice the ~20% reported for late-type galaxies (although differences in XUV-disk criteria complicate the comparison), possibly indicating that XUV disks are preferentially associated with galaxies experiencing weak or inefficient star formation. Consistent with this interpretation, we find that the XUV disks in our sample do not correlate with enhanced outer-disk star formation as traced by blue optical outer-disk colors. However, UV-Bright (UV-B) disk galaxies with blue UV colors outside their optical 50% light radii do display enhanced optical outer-disk star formation as well as enhanced atomic gas content. UV-B disks occur in our E/S0s with a 42^(+9)_–8% frequency and need not coincide with XUV disks; thus their combined frequency is 61% ± 9%. For both XUV and UV-B disks, UV colors typically imply <1 Gyr ages, and most such disks extend beyond the optical R_(25) radius. XUV disks occur over the full sample mass range and on both the red and blue sequences, suggesting an association with galaxy interactions or another similarly general evolutionary process. In contrast, UV-B disks favor the blue sequence and may also prefer low masses, perhaps reflecting the onset of cold-mode gas accretion or another mass-dependent evolutionary process. Virtually all blue E/S0s in the gas-rich regime below stellar mass M_t ~ 5 × 10^9 M_☉ (the "gas-richness threshold mass") display UV-B disks, supporting the previously suggested association of this population with active disk growth
The role of the maternal immune system in the regulation of human birth weight
This is the accepted manuscript version. It will be embargoed until 12 months after publication by RSC. The final version is available from RCS at http://rstb.royalsocietypublishing.org/content/370/1663/20140071.longHuman birth weight is subject to stabilizing selection. Large babies are at
risk of obstetric complications such as obstructed labour, which endangers
both mother and child. Small babies are also at risk with reduced survival.
Fetal growth requires remodeling of maternal spiral arteries to provide an
adequate maternal blood supply to the placenta. This arterial
transformation is achieved by placental trophoblast cells, which invade into
the uterine wall. Under invasion is associated with fetal growth restriction;
but if invasion is excessive large babies can result. A growing body of
evidence suggests that this process is controlled by interactions between KIR
receptors expressed on maternal uterine NK cells (uNK) and their
corresponding HLA-C ligands on invading trophoblast. Mothers with the KIR
AA genotype and a fetus with a paternal HLA-C2 allele tend to have small
babies, because this combination inhibits cytokine secretion by uNK.
Mothers with the activating KIR2DS1 gene and an HLA-C2 fetus are more
likely to have large babies. When KIR2DS1 binds to HLA-C2 this increases
secretion of cytokines that enhance trophoblast invasion. We conclude that
specific combinations of the highly polymorphic gene systems, KIR and HLAC,
contribute to successful reproduction by maintaining birth weight
between two extremes.This work was supported by
funding from the Wellcome Trust [090108/Z/09/Z], [085992/Z/08/Z] and
the British Heart Foundation [PG/09/077/27964]. This work was also
supported by a Frederick National Laboratory for Cancer Research Contract
[HHSN261200800001E] and by the Intramural Research Program of National
Institutes of Health, Frederick National Laboratory, Center for Cancer
Research. The authors also thank the Centre for Trophoblast Research,
Cambridge for generous support
Working Paper on Acknowledging and Repairing the Moral and Collective Harm of Ethnic Vietnamese Victims of the Khmer Rouge Genocide
How Do Uterine Natural Killer and Innate Lymphoid Cells Contribute to Successful Pregnancy?
Innate lymphoid cells (ILCs) are the most abundant immune cells in the uterine mucosa both before and during pregnancy. Circumstantial evidence suggests they play important roles in regulating placental development but exactly how they contribute to the successful outcome of pregnancy is still unclear. Uterine ILCs (uILCs) include subsets of tissue-resident natural killer (NK) cells and ILCs, and until recently the phenotype and functions of uILCs were poorly defined. Determining the specific roles of each subset is intrinsically challenging because of the rapidly changing nature of the tissue both during the menstrual cycle and pregnancy. Single-cell RNA sequencing (scRNAseq) and high dimensional flow and mass cytometry approaches have recently been used to analyse uILC populations in the uterus in both humans and mice. This detailed characterisation has significantly changed our understanding of the heterogeneity within the uILC compartment. It will also enable key clinical questions to be addressed including whether specific uILC subsets are altered in infertility, miscarriage and pregnancy disorders such as foetal growth restriction and pre-eclampsia. Here, we summarise recent advances in our understanding of the phenotypic and functional diversity of uILCs in non-pregnant endometrium and first trimester decidua, and review how these cells may contribute to successful placental development
How Do Uterine Natural Killer and Innate Lymphoid Cells Contribute to Successful Pregnancy?
Innate lymphoid cells (ILCs) are the most abundant immune cells in the uterine mucosa both before and during pregnancy. Circumstantial evidence suggests they play important roles in regulating placental development but exactly how they contribute to the successful outcome of pregnancy is still unclear. Uterine ILCs (uILCs) include subsets of tissue-resident natural killer (NK) cells and ILCs, and until recently the phenotype and functions of uILCs were poorly defined. Determining the specific roles of each subset is intrinsically challenging because of the rapidly changing nature of the tissue both during the menstrual cycle and pregnancy. Single-cell RNA sequencing (scRNAseq) and high dimensional flow and mass cytometry approaches have recently been used to analyse uILC populations in the uterus in both humans and mice. This detailed characterisation has significantly changed our understanding of the heterogeneity within the uILC compartment. It will also enable key clinical questions to be addressed including whether specific uILC subsets are altered in infertility, miscarriage and pregnancy disorders such as foetal growth restriction and pre-eclampsia. Here, we summarise recent advances in our understanding of the phenotypic and functional diversity of uILCs in non-pregnant endometrium and first trimester decidua, and review how these cells may contribute to successful placental development
- …