32 research outputs found
Expression patterns of class I KNOX and YABBY genes in Ruscus aculeatus (Asparagaceae) with implications for phylloclade homology
金沢大学大学院自然科学研究科生物多様性動態学金沢大学理学部STM (RaSTM) and YAB2 (RaYAB2) homologues were isolated from Ruscus aculeatus (Asparagaceae, monocots), and their expressions were analyzed by real-time polymerase chain reaction (PCR) to assess hypotheses on the evolutionary origin of the phylloclade in the Asparagaceae. In young shoot buds, RaSTM is expressed in the shoot apex, while RaYAB2 is expressed in the scale leaf subtending the shoot bud. This expression pattern is shared by other angiosperms, suggesting that the expression patterns of RaSTM and RaYAB2 are useful as molecular markers to identify the shoot and leaf, respectively. RaSTM and RaYAB2 are expressed concomitantly in phylloclade primordia. These results suggest that the phylloclade is not homologous to either the shoot or leaf, but that it has a double organ identity. © Springer-Verlag 2007
H Emission Nebulosity Associated with KH 15D
An H emission filament is found in close proximity to the unique object
KH 15D using the adaptive optics system of the Subaru Telescope. The morphology
of the filament, the presence of spectroscopic outflow signatures observed by
Hamilton et al., and the detection of extended H emission from KH 15D by
Deming, Charbonneau, & Harrington suggest that this filament arises from
shocked H in an outflow. The filament extends about 15" to the north of KH
15D.Comment: 11 pages, 3 figures, 1 table. Astrophysical Journal Letters, in pres
A Subarcsecond Companion to the T Tauri Star AS 353B
Adaptive optics imaging of the bright visual T Tauri binary AS 353 with the
Subaru Telescope shows that it is a hierarchical triple system. The secondary
component, located 5.6" south of AS 353A, is resolved into a subarcsecond
binary, AS 353Ba and Bb, separated by 0.24". Resolved spectroscopy of the two
close components shows that both have nearly identical spectral types of about
M1.5. Whereas AS 353A and Ba show clear evidence for an infrared excess, AS
353Bb does not. We discuss the possible role of multiplicity in launching the
large Herbig-Haro flow associated with AS 353A.Comment: AASTeXv5.0, 21 pages, 5 figures, Astronomical Journal, in pres
First Detection of NaI D lines in High-Redshift Damped Lyman-alpha Systems
A Near-infrared (1.18-1.35 micron) high-resolution spectrum of the
gravitationally-lensed QSO APM 08279+5255 was obtained with the IRCS mounted on
the Subaru Telescope using the AO system. We detected strong NaI D 5891,5897
doublet absorption in high-redshift DLAs at z=1.062 and 1.181, confirming the
presence of NaI, which was first reported for the rest-frame UV NaI
3303.3,3303.9 doublet by Petitjean et al. This is the first detection of NaI D
absorption in a high-redshift (z>1) DLA. In addition, we detected a new NaI
component in the z=1.062 DLA and four new components in the z=1.181 DLA. Using
an empirical relationship between NaI and HI column density, we found that all
"components" have large HI column density, so that each component is classified
as DLA absorption. We also detected strong NaI D absorption associated with a
MgII system at z=1.173. Because no other metal absorption lines were detected
in this system at the velocity of the NaI absorption in previously reported
optical spectra (observed 3.6 years ago), we interpret this NaI absorption
cloud probably appeared in the line of sight toward the QSO after the optical
observation. This newly found cloud is likely to be a DLA based upon its large
estimated HI column density. We found that the N(NaI)/N(CaII) ratios in these
DLAs are systematically smaller than those observed in the Galaxy; they are
more consistent with the ratios seen in the Large Magellanic Cloud. This is
consistent with dust depletion generally being smaller in lower metallicity
environments. However, all five clouds of the z=1.181 system have a high
N(NaI)/N(CaII) ratio, which is characteristic of cold dense gas. We tentatively
suggest that the host galaxy of this system may be the most significant
contributor to the gravitational-lens toward APM 08279+5255.Comment: 22 pages, 6 Postscript figures, 3 tables, ApJ in press (Vol.643, 2
June 2006
Direct Observation of the Extended Molecular Atmosphere of o Cet by Differential Spectral Imaging with an Adaptive Optics System
We present new measurements of the diameter of o Cet (Mira) as a function of
wavelength in the 2.2 micron atmospheric window using the adaptive optics
system and the infrared camera and spectrograph mounted on the Subaru
Telescope. We found that the angular size of the star at the wavelengths of CO
and H2O absorption lines were up to twice as large as the continuum
photosphere. This size difference is attributable to the optically thick CO and
H2O molecular layers surrounding the photosphere. This measurement is the first
direct differential spectroscopic imaging of stellar extension that resolves
individual molecular lines with high spectral-resolution observations. This
observation technique is extremely sensitive to differences in spatial profiles
at different wavelengths; we show that a difference in diameter much smaller
than the point spread function can be measured.Comment: 6 pages, 3 figures, accepted for publication in PAS
BHLHA15-Positive Secretory Precursor Cells Can Give Rise to Tumors in Intestine and Colon in Mice
Background & Aims: The intestinal epithelium is maintained by long-lived intestinal stem cells (ISCs) that reside near the crypt base. Above the ISC zone, there are short-lived progenitors that normally give rise to lineage-specific differentiated cell types but can dedifferentiate into ISCs in certain circumstances. However, the role of epithelial dedifferentiation in cancer development has not been fully elucidated. Methods: We performed studies with Bhlha15-CreERT, Lgr5-DTR-GFP, Apc flox/flox , LSL-Notch (IC), and R26-reporter strains of mice. Some mice were given diphtheria toxin to ablate Lgr5-positive cells, were irradiated, or were given 5-fluorouracil, hydroxyurea, doxorubicin, or dextran sodium sulfate to induce intestinal or colonic tissue injury. In intestinal tissues, we analyzed the fate of progeny that expressed Bhlha15. We used microarrays and reverse-transcription PCR to analyze gene expression patterns in healthy and injured intestinal tissues and in tumors. We analyzed gene expression patterns in human colorectal tumors using The Cancer Genome Atlas data set. Results: Bhlha15 identified Paneth cells and short-lived secretory precursors (including pre-Paneth label-retaining cells) located just above the ISC zone in the intestinal epithelium. Bhlha15 + cells had no plasticity after loss of Lgr5-positive cells or irradiation. However, Bhlha15 + secretory precursors started to supply the enterocyte lineage after doxorubicin-induced epithelial injury in a Notch-dependent manner. Sustained activation of Notch converts Bhlha15 + secretory precursors to long-lived enterocyte progenitors. Administration of doxorubicin and expression of an activated form of Notch resulted in a gene expression pattern associated with enterocyte progenitors, whereas only sustained activation of Notch altered gene expression patterns in Bhlha15 + precursors toward those of ISCs. Bhlha15 + enterocyte progenitors with sustained activation of Notch formed intestinal tumors with serrated features in mice with disruption of Apc. In the colon, Bhlha15 marked secretory precursors that became stem-like, cancer-initiating cells after dextran sodium sulfate–induced injury, via activation of Src and YAP signaling. In analyses of human colorectal tumors, we associated activation of Notch with chromosome instability-type tumors with serrated features in the left colon. Conclusions: In mice, we found that short-lived precursors can undergo permanent reprogramming by activation of Notch and YAP signaling. These cells could mediate tumor formation in addition to traditional ISCs
Common Fronto-temporal Effective Connectivity in Humans and Monkeys
Cognitive pathways supporting human language and declarative memory are thought to have uniquely evolutionarily differentiated in our species. However, cross-species comparisons are missing on site-specific effective connectivity between regions important for cognition. We harnessed a new approach using functional imaging to visualize the impact of direct electrical brain stimulation in human neurosurgery patients. Applying the same approach with macaque monkeys, we found remarkably comparable patterns of effective connectivity between auditory cortex and ventro-lateral prefrontal cortex (vlPFC) and parahippocampal cortex in both species. Moreover, in humans electrical tractography revealed rapid evoked potentials in vlPFC from stimulating auditory cortex and speech sounds drove vlPFC, consistent with prior evidence in monkeys of direct projections from auditory cortex to vocalization responsive regions in vlPFC. The results identify a common effective connectivity signature that from auditory cortex is equally direct to vlPFC and indirect to the hippocampus (via parahippocampal cortex) in human and nonhuman primates
Common Fronto-temporal Effective Connectivity in Humans and Monkeys
Human brain pathways supporting language and declarative memory are thought to have differentiated substantially during evolution. However, cross-species comparisons are missing on site-specific effective connectivity between regions important for cognition. We harnessed functional imaging to visualize the effects of direct electrical brain stimulation in macaque monkeys and human neurosurgery patients. We discovered comparable effective connectivity between caudal auditory cortex and both ventro-lateral prefrontal cortex (VLPFC, including area 44) and parahippocampal cortex in both species. Human-specific differences were clearest in the form of stronger hemispheric lateralization effects. In humans, electrical tractography revealed remarkably rapid evoked potentials in VLPFC following auditory cortex stimulation and speech sounds drove VLPFC, consistent with prior evidence in monkeys of direct auditory cortex projections to homologous vocalization-responsive regions. The results identify a common effective connectivity signature in human and nonhuman primates, which from auditory cortex appears equally direct to VLPFC and indirect to the hippocampus
Adaptive Optics Spectroscopy of the [Fe II] Outflows from HL Tauri and RW Aurigae
We present new results of [Fe II] 1.644-micron spectroscopy toward the jets
from HL Tau and RW Aur carried out with the Subaru Telescope combined with the
adaptive optics system. We observed the regions within 2" - 3" from the stars
with the sub-arcsecond resolutions of 0."5 and 0."2 for HL Tau and RW Aur,
respectively. In addition to the strong, high velocity emission extended along
each jet, we detected a blueshifted low velocity emission feature seen as a
wing or shoulder of the high velocity emission at each stellar position.
Detailed analysis shows that the position-velocity diagrams (PVDs) of HL Tau
and RW Aur show a characteristic similar to those of the cold disk wind and
X-wind models in that the [Fe II] line width is broad in the vicinity of the
stellar position and is narrower at the extended jet. A closer comparison
suggests, however, that the disk wind model tends to have too large line width
at the jet while the X-wind model has excess emission on the redshifted side at
the stellar position. The narrow velocity width with symmetric line profiles of
the observed high velocity emission supports an X-wind type model where the
launching region is localized in a small radial range, while the low velocity
emission located away from the star favors the presence of a disk wind. The [Fe
II] emission from the HL Tau jet shows a gap of 0."8 between the redshifted jet
and the star, indicating the presence of an optically thick disk of ~ 160 AU in
radius. The [Fe II] emission from the RW Aur jet shows a marked drop from the
redshifted peak at Y ~ -0."2 toward the star, suggesting that its disk radius
is smaller than 40 AU.Comment: Accepted in the ApJ (October 2006, v649n2), AAS LaTEX macros v 5.2,
Total 25 pages with 7 figure
Current Performance and On-Going Improvements of the 8.2 m Subaru Telescope
An overview of the current status of the 8.2 m Subaru Telescope constructed
and operated at Mauna Kea, Hawaii, by the National Astronomical Observatory of
Japan is presented. The basic design concept and the verified performance of
the telescope system are described. Also given are the status of the instrument
package offered to the astronomical community, the status of operation, and
some of the future plans. The status of the telescope reported in a number of
SPIE papers as of the summer of 2002 are incorporated with some updates
included as of 2004 February. However, readers are encouraged to check the most
updated status of the telescope through the home page,
http://subarutelescope.org/index.html, and/or the direct contact with the
observatory staff.Comment: 18 pages (17 pages in published version), 29 figures (GIF format),
This is the version before the galley proo