Revealing fine-scale cellular heterogeneity among spatial context and the functional and structural foundations of tissue architecture is fundamental within biological research and pharmacology. ...Unlike traditional approaches involving single molecules or bulk omics, cutting-edge, spatially resolved transcriptomics techniques offer near-single-cell or even subcellular resolution within tissues. Massive information across higher dimensions along with position-coordinating labels can better map the whole 3D transcriptional landscape of tissues. In this review, we focus on developments and strategies in spatially resolved transcriptomics, compare the cell and gene throughput and spatial resolution in detail for existing methods, and highlight the enormous potential in biomedical research.
To accurately reflect organ architecture, spatially resolved transcriptomics aims to provide spatial and expression information at the single cellular level for higher-order reconstruction.In silico methods combine single-cell RNA sequencing (scRNA-seq), in situ hybridization, and prior knowledge to reconstruct spatial transcriptomes of tissues but cannot match coordinates and tend to simplify.Laser capture microdissection (LCM)-based approaches allow full gene single-cell profiling plus position information, but assay only a few cells.RNA imaging provides the expression landscape for millions of cells in situ but detects only targeted transcripts.In situ sequencing provides spatial whole genome-wide expression at the micron level by combining barcoding with NGS but fails to describe individual cells.
Abstract
JWST is revolutionizing our understanding of the high-
z
Universe by expanding the black hole horizon, looking farther and to smaller masses, and revealing the stellar light of their hosts. ...By examining JWST galaxies at
z
= 4–7 that host H
α
-detected black holes, we investigate (i) the high-
z
M
•
–
M
⋆
relation and (ii) the black hole mass distribution, especially in its low-mass range (
M
•
≲ 10
6.5
M
⊙
). With a detailed statistical analysis, our findings conclusively reveal a high-
z
M
•
–
M
⋆
relation that deviates at >3
σ
confidence level from the local relation. The high-
z
relation is
log
(
M
•
/
M
⊙
)
=
−
2.43
−
0.83
+
0.83
+
1.06
−
0.09
+
0.09
log
(
M
⋆
/
M
⊙
)
. Black holes are overmassive by ∼10–100× compared to their low-
z
counterparts in galactic hosts of the same stellar mass. This fact is not due to a selection effect in surveys. Moreover, our analysis predicts the possibility of detecting in high-
z
JWST surveys 5–15× more black holes with
M
•
≲ 10
6.5
M
⊙
, and 10–30× more with
M
•
≲ 10
8.5
M
⊙
, compared to local relation’s predictions. The lighter black holes preferentially occupy galaxies with a stellar mass of ∼10
7.5
–10
8
M
⊙
. We have yet to detect these sources because (i) they may be inactive (duty cycles 1%–10%), (ii) the host overshines the active galactic nucleus (AGN), or (iii) the AGN is obscured and not immediately recognizable by line diagnostics. A search of low-mass black holes in existing JWST surveys will further test the
M
•
–
M
⋆
relation. Current JWST fields represent a treasure trove of black hole systems at
z
= 4–7; their detection will provide crucial insights into their early evolution and coevolution with their galactic hosts.
For multicellular organisms, cell-cell communication is essential to numerous biological processes. Drawing upon the latest development of single-cell RNA-sequencing (scRNA-seq), high-resolution ...transcriptomic data have deepened our understanding of cellular phenotype heterogeneity and composition of complex tissues, which enables systematic cell-cell communication studies at a single-cell level. We first summarize a common workflow of cell-cell communication study using scRNA-seq data, which often includes data preparation, construction of communication networks, and result validation. Two common strategies taken to uncover cell-cell communications are reviewed, e.g., physically vicinal structure-based and ligand-receptor interaction-based one. To conclude, challenges and current applications of cell-cell communication studies at a single-cell resolution are discussed in details and future perspectives are proposed.
We present the HST WFC3/F275W UV imaging observations of A2218-Flanking, a lensed compact dwarf galaxy at redshift . The stellar mass of A2218-Flanking is and SFR is yr−1 after correcting the ...magnification. This galaxy has a young galaxy age of 127 Myr and a compact galaxy size of . The HST UV imaging observations cover the rest-frame Lyman continuum (LyC) emission (∼800 ) from A2218-Flanking. We firmly detect ( ) the LyC emission in A2218-Flanking in the F275W image. Together with the HST F606W images, we find that the absolute escape fraction of LyC is based on the flux density ratio between 1700 and 800 ( ). The morphology of the LyC emission in the F275W images is extended and follows the morphology of the UV continuum morphology in the F606W images, suggesting that the f800 is not from foreground contaminants. We find that the region with a high star formation rate surface density has a lower (higher ) ratio than the diffused regions, suggesting that LyC photons are more likely to escape from the region with the intensive star-forming process. We compare the properties of galaxies with and without LyC detections and find that LyC photons are easier to escape in low-mass galaxies.
We present results from a spectroscopic survey of z ∼ 5 quasars in the CFHT Legacy Survey. Using both optical color selection and a likelihood method, we select 97 candidates over an area of 105 deg2 ...to a limit of iAB < 23.2, and 7 candidates in the range 23.2 < iAB < 23.7 over an area of 18.5 deg2. Spectroscopic observations for 43 candidates were obtained with Gemini, MMT, and Large Binocular Telescope, of which 37 are z > 4 quasars. This sample extends measurements of the quasar luminosity function ∼1.5 mag fainter than our previous work in Sloan Digital Sky Survey Stripe 82. The resulting luminosity function is in good agreement with our previous results, and suggests that the faint end slope is not steep. We perform a detailed examination of our survey completeness, particularly the impact of the Ly emission assumed in our quasar spectral models, and find hints that the observed Ly emission from faint z ∼ 5 quasars is weaker than for z ∼ 3 quasars at a similar luminosity. Our results strongly disfavor a significant contribution of faint quasars to the hydrogen-ionizing background at z = 5.
Abstract
We present a mock catalog of gravitationally-lensed quasars at
z
qso
< 7.5 with simulated images for the Rubin Observatory Legacy Survey of Space and Time (LSST). We adopt recent ...measurements of quasar-luminosity functions to model the quasar population, and use the CosmoDC2 mock galaxy catalog to model the deflector galaxies, which successfully reproduces the observed galaxy-velocity dispersion functions up to
z
d
∼ 1.5. The mock catalog is highly complete for lensed quasars with Einstein radius
θ
E
> 0.″07 and quasar absolute magnitude
M
i
< − 20. We estimate that there are ∼10
3
lensed quasars discoverable in current imaging surveys, and LSST will increase this number to ∼ 2.4 × 10
3
. Most of the lensed quasars have image separation Δ
θ
> 0.″5, which will at least be marginally resolved in LSST images with seeing of ∼0.″7. There will be ∼200 quadruply-lensed quasars discoverable in the LSST. The fraction of quad lenses among all discoverable lensed quasars is about ∼10%–15%, and this fraction decreases with survey depth. This mock catalog shows a large diversity in the observational features of lensed quasars, in terms of lensing separation and quasar-to-deflector flux ratio. We discuss possible strategies for a complete search of lensed quasars in the LSST era.
Strong gravitational lensing provides a powerful probe of the physical properties of quasars and their host galaxies. A high fraction of the most luminous high-redshift quasars was predicted to be ...lensed due to magnification bias. However, no multiple imaged quasar was found at z > 5 in previous surveys. We report the discovery of J043947.08+163415.7, a strongly lensed quasar at z = 6.51, the first such object detected at the epoch of reionization, and the brightest quasar yet known at z > 5. High-resolution Hubble Space Telescope imaging reveals a multiple imaged system with a maximum image separation θ ∼ 0 2, best explained by a model of three quasar images lensed by a low-luminosity galaxy at z ∼ 0.7, with a magnification factor of ∼50. The existence of this source suggests that a significant population of strongly lensed, high-redshift quasars could have been missed by previous surveys, as standard color selection techniques would fail when the quasar color is contaminated by the lensing galaxy.
Abstract
We present the first results from a new survey for high-redshift (
z
≳ 5) gravitationally lensed quasars and close quasar pairs. We carry out candidate selection based on the colors and ...shapes of objects in public imaging surveys, then conduct follow-up observations to confirm the nature of high-priority candidates. In this paper, we report the discoveries of J0025–0145 (
z
= 5.07), which we identify as an intermediately lensed quasar, and J2329–0522 (
z
= 4.85), which is a kiloparsec-scale close quasar pair. The Hubble Space Telescope (HST) image of J0025–0145 shows a foreground lensing galaxy located 0.″6 away from the quasar. However, J0025–0145 does not exhibit multiple lensed images of the quasar, and we identify J0025–0145 as an intermediate lensing system (a lensing system that is not multiply imaged but has a significant magnification). The spectrum of J0025–0145 implies an extreme Eddington ratio if the quasar luminosity is intrinsic, which could be explained by a large lensing magnification. The HST image of J0025–0145 also indicates a tentative detection of the quasar host galaxy in the rest-frame UV, illustrating the power of lensing magnification and distortion in studies of high-redshift quasar host galaxies. Object J2329–0522 consists of two resolved components with significantly different spectral properties and a lack of lensing galaxy detection under subarcsecond seeing. We identify it as a close quasar pair, which is the highest confirmed kiloparsec-scale quasar pair to date. We also report four lensed quasars and quasar pairs at 2 <
z
< 4 and discuss possible improvements to our survey strategy.
We present a survey of the C ii 158 m line and underlying far-infrared (FIR) dust continuum emission in a sample of 27 quasars using the Atacama Large Millimeter Array (ALMA) at resolution. The C ii ...line was significantly detected (at - ) in 23 sources (85%). We find typical line luminosities of , and an average line width of ∼385 . The C ii-to-far-infrared luminosity ratios (C ii/FIR) in our sources span one order of magnitude, highlighting a variety of conditions in the star-forming medium. Four quasar host galaxies are clearly resolved in their C ii emission on a few kpc scales. Basic estimates of the dynamical masses of the host galaxies give masses between 2 × 1010 and 2 × 1011 , i.e., more than an order of magnitude below what is expected from local scaling relations, given the available limits on the masses of the central black holes ( , assuming Eddington-limited accretion). In stacked ALMA C ii spectra of individual sources in our sample, we find no evidence of a deviation from a single Gaussian profile. The quasar luminosity does not strongly correlate with either the C ii luminosity or equivalent width. This survey (with typical on-source integration times of 8 minutes) showcases the unparalleled sensitivity of ALMA at millimeter wavelengths, and offers a unique reference sample for the study of the first massive galaxies in the universe.
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![An ALMA [C ii] Survey of 27...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-637X/small "An ALMA [C ii] Survey of 27 Quasars at z > 5.94")
