Ring-like Distribution Research Articles

The lithosphere structure of Northeast China

The lithosphere of northeastern China is composed of the Erguna, Xingan, Songnen, Jiamusi blocks and Mesozoic Wandashan accretionary complex from west to east. Nd isotope model ages indicate that the Xingan and Songnen blocks have the same Nd model ages ranging from 500 to 1 000 Ma. These are obviously younger than those of the Jiamusi block (1 500–2 000 Ma) and the Erguna block (1 500–1 700 Ma), reflecting the different evolutions of individual blocks in the early times. Geochemical tracing analysis shows that the Nd model ages of Paleozoic supercrustal rocks in the four blocks are dominantly Mesoproterozoic, while those of Mesozoic granites are mainly Neoproterozoic. It is shown that the crust ages of the region are characterized by being younger in the lower part and older in the upper part. The Os isotope analysis also indicates that the lithosphere mantle of the region is characteristic of a younger age. The P-wave velocities of the region show more complicated structures in lithosphere and asthenosphere. First of all, notably different from traditional concept of the seismic lithosphere, the low velocity zone of the lithosphere beneath the region has no persistent and continuous top interface which is highly varied in depth and intersected with the high velocity layers, forming sharp velocity discontinuities beneath major tectonic belts, even up to the Moho beneath some tectonic units. But the bottom interface of the low velocity zone is relatively persistent, occurring at a depth of 230–240 km. Another feature is that the lithosphere is characterized by an “overpass type” velocity structure vertically, in which the contoured velocity is distributed in the NE trending within the crust, in a nearly NS trending in the lithosphere mantle from a depth of 45 to 90 km, in a nearly EW trending in the upper part of the asthenosphere from 90 to 170 km and in a ring-like distribution with a diameter of about 300 km in the lower part of the asthenosphere from 170 to 240 km. The P-wave velocity is progressively increasing from 240 to 400 km.

Nocardia Keratitis

To correlate the clinical presentation and treatment outcome of Nocardia keratitis with the time to diagnosis, different species and with the drug sensitivity pattern. Patients with Nocardia corneal ulcers were studied at a tertiary eye care center. Speciation of Nocardia isolates was done by sequencing the 16s rRNA gene. Clinical response to treatment was assessed by chart review. Twenty one (65.3%) patients presented within 15 days of the onset of symptoms with typical clinical features of Nocardia keratitis, ie, a ring-like distribution of superficial infiltrates in a wreath pattern. Eight patients (25%) who presented after 15 days and within 30 days had an ulcer resembling fungal keratitis. N. Cyriacigeorgica (n = 11; 34.37%), N. asteroides (n = 9; 28%), N. farcinica (n = 7; 22%,) and N. Otitidiscaviarum (n = 5; 16%). All the species had 100% sensitivity to amikacin, sulphamethoxazole, imipenem and co-trimoxazole. Time to diagnosis of the infection was significantly associated with the different types of clinical presentation; those presenting early having the typical clinical picture (P = 0.004). Patients (73%) presenting within 15 days showed a highest recovery rate. (P = 0.045). The recovery time of the patients when compared with species showed those who were infected with N. cyriageorgica had a healing time of less than 15 days. Clinically, healing was faster when treated with 2% amikacin. Visual outcome improved in fourteen patients (44%) and sixteen (50%) patients remained the same (P = 0.0001). Characteristic clinical picture of Nocardia is dependant on early presentation. It could be mistaken for fungal keratitis. Microbiological confirmation is important. Drug of choice for Nocardia keratitis is amikacin.

Maser emission towards the young planetary nebula IRAS 17347-3139

AbstractWe have re-analyzed observations of the water maser emission in IRAS 17347-3139 carried out previously and compared them with new higher angular resolution and more sensitive radio-continuum observations to explain the shift between the position of the peak of the radio-continuum with respect to the center of the ring-like distribution. From our analysis, we found that the water maser emission is not distributed in a closed ring-like structure, but in what appears to be a segment of an ellipse centered in the position of the peak of the radio-continuum. These results can explain the shift between the radio-continuum and the water maser emission. We also present interferometric observations of the OH maser emission towards IRAS 17347-3139 from which we have found that the OH maser emission detected previously is not associated with this source. Furthermore, since our observations are more sensitive, we have detected for the first time weak OH maser emission associated with IRAS 17347-3139.

Second generation of Moore-Read quasiholes in a composite-fermion liquid

Two- and three-body correlations of incompressible quantum liquids are studied numerically. Pairing of composite fermions (CFs) in the 1/3-filled second CF Landau level is found at nu_e=4/11. It is explained by reduced short-range repulsion due to ring-like single-particle charge distribution. Although Moore-Read state of CFs is unstable in the 1/2-filled second CF level, condensation of its quasiholes is a possible origin of incompressibility at nu_e=4/11. Electron pairing occurs at nu_e=7/3 and 13/3, but with different pair-pair correlations. Signatures of triplets are found at higher fillings.

PROBLEMS WITH SPECIES: PATTERNS AND PROCESSES OF SPECIES FORMATION IN SALAMANDERS1

How many species one recognizes within a given taxon remains a difficult question, especially when morphology is relatively stable or when clinal variation is present, thus complicating diagnosis. I accept the general lineage concept of species, and my goal is to recognize historically distinct evolutionary lineages that are likely to remain distinct. Here I analyze this task with respect to patterns of species formation in two genera of plethodontid salamanders in California. Ensatina is a ring species complex surrounding the Central Valley of California. At present it is a single species with seven subspecies that are linked by apparent clinal variation in intergrade zones, but there are also some narrow hybrid zones where morphologically and ecologically differentiated forms interact. In contrast, Batrachoseps, which has much the same distribution, has about 20 species in California, most occurring in sympatry with Ensatina. Divergence in the two taxa is based on two fundamentally different phenomena, and yet there are some common themes. Adaptive divergence in coloration is the dominant theme in Ensatina, whereas differentiation is largely perceived at the molecular level in Batrachoseps. Yet both have evolved in the same region and have been affected by many of the same climatic and earth historical phenomena. Within the Ensatina complex, different adaptations related to predator avoidance have evolved. Coloration has diverged in different directions in coastal and inland populations, even though genetic interactions continue to take place. Where coastal populations meet other coastal populations, ecologically and morphologically similar populations merge genetically, even if well differentiated in molecular traits. In contrast, where the ring is crossed and where ecologically and morphologically differentiated populations meet, they hybridize narrowly or are sympatric and behave as if they are species. Within the ring-like distribution, clinal patterns of variation occur. The current polytypic taxonomy is retained, even though it is problematic, because alternatives are even less appropriate. In contrast, where genetically differentiated populations of Batrachoseps meet they typically do not merge. Instead, they replace one another spatially, in part because they are so similar ecologically. Apparently the periods of isolation were sufficiently long that even in the absence of adaptive divergence there has been divergence of isolating mechanisms. Analysis of patterns of genetic differentiation in allozymes and mtDNA in relation to the geological history of California is used to generate biogeographic scenarios to help explain the contrast between Batrachoseps and Ensatina.

Diffraction of conic and Gaussian beams by a spiral phase plate

An analytical expression for the spatial spectrum of the conic wave diffracted by a spiral phase plate (SPP) with arbitrary integer singularity of order n is obtained. Conic wave diffraction by the SPP is equivalent to plane-wave diffraction by a helical axicon. A comparison of the conic wave and Gaussian beam diffraction on a SPP is made. It is shown that in both cases a light ring is formed, with the intensity function growing in proportion to rho(2n) at small values of radial variable rho and decreasing as n(2)rho(-4) at large rho. By use of direct e-beam writing on the resist, a 32 level SPP of the 2nd order and diameter 5 mm is manufactured. By use of this SPP, a He-Ne laser beam is transformed into a beam with phase singularity and ringlike intensity distribution. A four-order binary diffractive optical element (DOE) with its transmittance proportional to a linear superposition of four angular harmonics is also manufactured. With this DOE, simultaneous optical trapping of several polystyrene beads of diameter 5 microm is performed.

Inward Motions of the Compact SiO Masers around VX Sagittarii

We report Very Long Baseline Array (VLBA) observations of 43 GHz v=1, J=1-0 SiO masers in the circumstellar envelope of the M-type semi-regular variable star VX Sgr at 3 epochs during 1999 April-May. These high-resolution VLBA images reveal a persistent ringlike distribution of SiO masers with a projected radius of ~3 stellar radii. The typical angular size of 0.5 mas for individual maser feature was estimated from two-point correlation function analysis for maser spots. We found that the apparent size scale of maser features was distinctly smaller than that observed in the previous observations by comparing their fractions of total power imaged. This change in the size scale of maser emission may be related to stellar activity that caused a large SiO flare during our observations. Our observations confirmed the asymmetric distribution of maser emission, but the overall morphology has changed significantly with the majority of masers clustering to the north-east of the star compared to that lying to the south-west direction in 1992. By identifying 42 matched maser features appearing in all the three epochs, we determined the contraction of an SiO maser shell toward VX Sgr at a proper motion of -0.507 mas/yr, corresponding to a velocity of about 4 km/s at a distance of 1.7 kpc to VX Sgr. Such a velocity is on the order of the sound speed, and can be easily explained by the gravitational infall of material from the circumstellar dust shell.

Self-organized MnAs quantum dots formed during annealing of GaMnAs under arsenic capping

Formation of MnAs quantum dots in a regular ring-like distribution has been found on molecular beam epitaxy grown (GaMn)As(100) surfaces after low-temperature annealing under As capping. The appearance of the dots depends on the thickness and Mn concentration in the (GaMn)As layer. With 5 at. % substitutional Mn the quantum dots showed up for layers thicker than 100 nm. For thinner layers the surfaces of the annealed samples are smooth and well ordered with 1×2 surface reconstruction, just as for as-grown (GaMn)As. The annealed surfaces are Mn rich, and are well suited for continued epitaxial growth.

The disrupted molecular envelope of Frosty Leo

We present maps of CO emission in the protoplanetary nebula Frosty Leo. Observations of the rotational transitions ^(12)CO J=2-1 and 1-0 have been obtained with the IRAM interferometer and the OVRO array. The molecular envelope of Frosty Leo is found to be complex and compact; most of the gas extends ≾6 and shows a structure that is very different to the extended optical nebula. It is composed of a central ring-like structure, whose symmetry axis is inclined ~-40° with respect to the sky plane and expands at speeds of up to ~30 km s^(-1), and high-velocity jets distributed along the symmetry axis of the ring, which reach expansion velocities as high as ~75 km s^(-1). The symmetry axis of the molecular jets in the plane of the sky coincides with the direction of some jet-like features seen in the optical, which are not aligned at all with the main symmetry axis of the optical nebula. The brightness distribution of the ring presents a clumpy structure. We have modeled the spatio-kinematical distribution of, and the excitation conditions in, the molecular envelope. For both transitions, the ^(12)CO emission is found to be very optically thick in the center of the nebula. From our best-fit model, we find that the nebular particle density varies between ~10^5 cm^(-3) and ~10^3 cm^(-3), and that the rotational temperature is very low, ~10 K. The kinematical lifetime of the molecular jets is ~1700 yr, long in comparison with the lifetime of the post-AGB winds of most PPNe. It is very remarkable that the bulk of the gas accelerated during the post-AGB phase of Frosty Leo is located within the central ring, reaching expansion velocities of up to ~30 km s^(-1). The central ring-like distribution of Frosty Leo is probably not the undisrupted remnant of the previous AGB envelope (as found for most PPNe), but its dynamics likely result from multiple post-AGB interactions.

Vascular Flow Patterns of Hepatic Tumors in Contrast-Enhanced 3-Dimensional Fusion Ultrasonography Using Plane Shift and Opacity Control Modes

This study was conducted to determine whether contrast-enhanced 3-dimensional (3D) fusion ultrasonography with combined use of the plane shift and opacity control modes can serve as a useful tool for identifying the vascular characteristics of hepatic tumors in 3D perspective. Contrast-enhanced 3D fusion ultrasonography was performed in 31 patients with hepatic tumors after the intravenous injection of contrast media. The shapes, courses, and distributions of tumor vessels, displayed in 3D perspective, were examined to identify the characteristic vascular flow patterns of various tumors. Images before and after contrast media administration were compared for evaluation of the effectiveness of contrast enhancement with regard to tumor diameter for various types of tumors. The images were interpreted in a blinded manner by 3 physicians specializing in abdominal ultrasonography, and vascular flow patterns were determined on the basis of consensus. The characteristic vascular flow patterns observed in hepatocellular carcinomas are reticular flow within the tumor and flow showing a ringlike distribution surrounding the tumor. Metastatic tumors show a vascular flow pattern running between adjacent tumor nodules, and hemangiomas show localized nodular flow at the tumor margins. Contrast enhancement was found to be useful for showing the vascular flow patterns in small hepatocellular carcinomas and hemangiomas. Contrast-enhanced 3D fusion ultrasonography makes it possible to display images combining the plane shift and opacity control modes to show tumor vessels, including minute vascular flow within hepatic tumors, in 3D perspective and to identify tumor-specific vascular flow patterns.

The Scent of an Ovum?

Sperm chemotaxis toward the egg plays a critical role in fertilization; however, the underlying mechanisms remain poorly understood. Spehr et al ., who recently showed that human sperm exhibited chemotaxis to the floral scent bourgeonal [which binds the olfactory receptor (OR) protein hOR17-4, thereby activating an adenosine 3′,5′-monophosphate (cAMP)-mediated pathway, eliciting Ca 2+ influx, and modifying flagellar beating], further investigated the mechanisms linking hOR17-4 activation to changes in sperm swimming. The authors used a multidimensional protein identification technology (MudPIT) approach based on two-dimensional liquid chromatography and mass spectroscopy to show that human spermatazoa expressed the G olf "olfactory specific" heterotrimeric guanine nucleotide-binding protein α subunit, as well as all nine mammalian isoforms of membrane-bound adenylyl cyclase (mAC). hOR17-4 expression, previously determined on the basis of functional assays, was confirmed as well. Immunofluorescence analysis for G olf , mAC III, and mAC VIII revealed that mAC VIII was localized to the flagellum, whereas mAC III was localized to the head and midpiece. mAC localization depended on acrosome status and showed a ringlike distribution in sperm that had not undergone the acrosome reaction and spreading through the heads of acrosome-reacted spermatazoa. G olf was found in the tail and midpiece. Ca 2+ signals elicited by bourgeonal originated in the midpiece before spreading to the head. Pharmacological analysis indicated that both the Ca 2+ signal and behavioral responses to bourgeonal depended on mAC and not on soluble AC (which has been identified in mammalian sperm). Thus, membrane-associated AC appears to be critically involved in Ca 2+ influx and sperm chemotaxis. M. Spehr, K. Schwane, J. A. Riffell, J. Barbour, R. K. Zimmer, E. M. Neuhaus, H. Hatt, Particulate adenylate cyclase plays a key role in human sperm olfactory receptor-mediated chemotaxis. J. Biol. Chem . 279 , 40194-40203 (2004). [Abstract] [Full Text]

Chondrocyte interactions with porous titanium alloy and calcium polyphosphate substrates

Chondrocytes maintain their phenotype and form cartilagenous tissue when cultured on calcium polyphosphate (CPP) or titanium alloy (Ti alloy), porous three-dimensional materials. To understand how these materials may influence chondrocyte phenotype and matrix synthesis, the early interactions of cultured cells with CPP and titanium alloy were examined. These were compared to chondrocytes grown in monolayer culture on tissue culture polystyrene, conditions in which cultured chondrocytes dedifferentiate and do not form cartilagenous tissue. Scanning electron microscopy of cells up to 72 h in culture showed that bovine chondrocytes on CPP, Ti alloy, and polystyrene were an admixture of round and spread cells. The spread cells on CPP and titanium alloy were not entirely flattened but maintained a polygonal shape. In contrast, spread chondrocytes in monolayer culture were flatter and significantly larger, a difference that was maintained even in the absence of serum. All cells cultured on CPP and Ti alloy exhibited subcortical ring-like distribution of actin filaments whereas the flattened cells on polystyrene showed actin filaments distributed throughout the cytoplasm. Cells on CPP and Ti alloy synthesized significantly less collagen and proteoglycans than cells cultured on polystyrene at 72 h of culture. In summary the cells on the porous three-dimensional materials differed from those on polystyrene in terms of cell morphology and size, actin cytoskeleton organization, and synthesis of selected matrix macromolecules. The data suggests that CPP and titanium alloy may mediate their effect by limiting cell spreading in part by favoring the maintenance of a ring-like actin distribution.

Ring formation of focused half-cycle terahertz pulses

Studies using a terahertz (THz) imaging system have shown that focused THz electromagnetic pulses exhibit a ring-like spatial intensity distribution. In the study, almost half-cycle THz pulses were generated from a large-aperture photoconductive antenna and focused by an off-axis parabolic mirror. Time-resolved spatial distribution of the THz electric field on the focal plane was found to form a ring before and after the time region where a single peak is formed around the time origin. On the other hand, with the delay time fixed at the origin, the field distribution was also found to exhibit a ring-like profile at positions away from the focal plane. Existence of relatively low-frequency components in the power spectrum of the THz field gives these observable phenomena. Numerical simulations using diffraction integral calculations reproduced the observed features. A simpler numerical analysis based on the Gaussian beam approximation was shown to yield the observed features and also predicted the dependence on the beam parameters.

COHERENT SCATTERING OF ULTRAVIOLET LIGHT BY AVIAN FEATHER BARBS

Abstract Ultraviolet (UV) structural colors of avian feathers are produced by the spongy medullary keratin of feather barbs, but various physical mechanisms have been hypothesized to produce those colors, including Rayleigh scattering, Mie scattering, and coherent scattering (i.e. constructive interference). We used two-dimensional Fourier analysis of transmission electron micrographs of the medullary keratin of UV-colored feather barbs of the Blue Whistling Thrush (Myiophonus caeruleus) (Turdidae) to test the alternative hypotheses for production of those UV structural hues. The two-dimensional Fourier power spectra of the tissue reveal a ring-like distribution of peak periodicity at intermediate spatial frequencies (∼0.078 nm −1), which documents that Myiophonus medullary keratin is substantially nanostructured and equivalently ordered in all directions. This nanoscale spatial order falsifies a basic assumption of both the Rayleigh scattering and Mie scattering. A predicted reflectance spectrum based on...

Centromere-specific acetylation of histone H4 in barley detected through three-dimensional microscopy.

Histone acetylation affects chromatin conformation and transcriptional activity. However, the structural role of histone acetylation at specific chromosomal regions, such as the centromere, is poorly understood. In this study, histone H4 acetylation and its localization in barley interphase nuclei are revealed by three-dimensional microscopy. The centromeres form a ring-like allocation near the nuclear membrane in barley. Immunofluorescence studies on non-fixed, interphase nuclei treatment revealed ring-like distribution of the highly acetylated histone H4, located near the nuclear membrane at one pole of the nucleus. This fluorescent structure was similar to the centromere cluster and referred to as hyperacetylated region (HAR). The distribution pattern of the acetylated histone H4 was similar to each of the K5, K8, K12 and K16 lysine residues, although H4 acetylated at K5, K8 and K12 residues was found in almost all nuclei, whereas H4 acetylated at K16 was weakly observed in only half of the nuclei. Each HAR consists of two strongly acetylated cores and a halo-like, less acetylated surrounding area. Fluorescence signals from centromere-specific repetitive sequences of barley, detected through three-dimensional fluorescence in situ hybridization (3D-FISH), co-localized with the HAR corresponding to the K5 residue acetylation, but the signals did not completely overlap each other. These findings indicate that histone acetylation specifically occurring at the centromeres likely have certain structural roles for the centromere.

Coherent Scattering of Ultraviolet Light by Avian Feather Barbs

Abstract Ultraviolet (UV) structural colors of avian feathers are produced by the spongy medullary keratin of feather barbs, but various physical mechanisms have been hypothesized to produce those colors, including Rayleigh scattering, Mie scattering, and coherent scattering (i.e. constructive interference). We used two-dimensional Fourier analysis of transmission electron micrographs of the medullary keratin of UV-colored feather barbs of the Blue Whistling Thrush (Myiophonus caeruleus) (Turdidae) to test the alternative hypotheses for production of those UV structural hues. The two-dimensional Fourier power spectra of the tissue reveal a ring-like distribution of peak periodicity at intermediate spatial frequencies (∼0.078 nm −1), which documents that Myiophonus medullary keratin is substantially nanostructured and equivalently ordered in all directions. This nanoscale spatial order falsifies a basic assumption of both the Rayleigh scattering and Mie scattering. A predicted reflectance spectrum based on the Fourier power spectra matches hue of the measured reflectance spectra of the feathers (345 nm). These results demonstrate that the Myiophonus medullary keratin is ordered at the appropriately nanoscale to produce the observed UV hues by coherent scattering.

Formation of stacking faults in nitrogen-doped silicon single crystals

The behavior of the ring-like distribution of oxidation-induced stacking faults (OSFs) in nitrogen-doped Czochralski grown single silicon crystals was investigated as a function of the nitrogen and oxygen content. It was found that the inner and outer boundary of the OSF ring is shifted towards the crystal center with higher nitrogen concentration, while, at the same time, the width of the OSF ring increases. This result can be explained by a qualitative model which takes into account the nitrogen-induced change in the temperature-dependent variation of the vacancy concentration. Without nitrogen doping the OSF ring disappears if the oxygen content drops below a critical value. However, the OSF ring reappears at a sufficient nitrogen doping level. The lower the oxygen content, the higher the nitrogen concentration must be to observe an OSF ring. It is shown that this can be understood using the same qualitative model if a critical width of the OSF ring is introduced below which the OSF ring is no longer detectable.

Mm-VLBI observations of SiO masers: Further support for radiative pumping and rotation of the inner shell

We have performed VLBA observations of the SiO v = 1 and v = 2 J = 1-0 masers in two AGB stars, TX Cam and IRC +10011. We confirm the ring-like spatial distribution, previously found in several AGB objects, as well as the tangential polarization pattern, already reported for TX Cam. Both properties, that seem to be systematic in this kind of objects, are characteristic of radiatively pumped SiO masers. On the contrary, we do not confirm the previous report on the spatial coincidence between the J = 1-0 v = 1 and 2 masers, a result that would have argued in favor of collisional pumping. We find that both lines sometimes arise from nearby spots, typically separated by 1-2 mas, but are rarely coincident. The discrepancy with previous results is explained by the very high spatial resolution of our observations, ∼ 0.5 mas, an order of magnitude better than in the relevant previously published experiment. Moreover, we have been able to measure a probable rotation of the inner shell of a few km/s. Rotation of circumstellar shells is assumed by the most convincing models explaining the drastic change of symmetry between the AGB envelopes (spherical symmetry) and Proto Planetary Nebulae (axial symmetry).

Warm gas in central regions of nearby galaxies

We have mapped the CO(3-2) line emission from several nearby galaxies, using the Heinrich-Hertz-Telescope on Mt. Graham, Arizona. Unlike earlier observations, our investigation is not restricted to starburst galaxies, but includes twelve galaxies of various types and in different stages of star forming activity. Furthermore, we have not only observed the central positions of these objects, but have obtained maps of the extended CO(3-2) emission, with a typical map extent of 2 to 3 arcmin in each direction. Our observations show that this extended mapping is necessary to reveal spatial changes of the ISM properties within the galaxies. In this paper we present the data sets and some data analysis. We compare the galaxies in view of their morphology and excitation conditions, using line ratios, luminosities and other properties, like the extent of the CO(3-2) emission. The main results of this CO(3-2) survey are: 1. In none of the observed objects the emission is confined to the nucleus, as claimed in some earlier publications. CO(3-2) emission can be detected for some objects to the same extent as the CO(2-1) and the CO(1-0) lines. 2. The emission is more concentrated to the vicinity of star forming structures (nuclear regions and spiral arms) than the lower CO transitions for most of the observed objects. This is shown by decreasing (3-2)/(1-0) line intensity ratios from the very centres towards larger radii. The (deconvolved) sizes of the central emission peaks in the CO(3-2) line vary from about 300 pc up to 3 kpc. 3. The CO(3-2) luminosity is stronger in objects that contain a nuclear starburst or morphological peculiarities. The total power emitted in the CO(3-2) line from the central regions (i.e. excluding spiral arms/outer disk) is highest in the starburst galaxies NGC 2146, M 82, NGC 3628, and in the spiral galaxy M 51. When comparing the total power normalized to the size of the emission region, the starburst galaxies M 82 and NGC 253 show the highest values (about three times higher than most other objects), while NGC 278 and NGC 4631 show the lowest. 4. With the present spatial resolution, the line ratios seem to be independent of Hubble type, color or luminosity. Most galaxies with enhanced central star formation ("starbursts" ) show line ratios of the integrated intensities of in the very centre and ~1.0 at a radius of about 1 kpc. Objects with a ring-like (or double-peak if seen edge-on) molecular gas distribution (NGC 253, M 82, and NGC 4631) show lower ratios. The two galaxies that have CO(3-2) emission distributed over their spiral arms (NGC 891 and M 51) show very low line ratios despite their high infrared luminosities. This result suggests that CO emission in these objects reflects a large amount of molecular gas, but not enhanced star forming activity. 5. Starburst galaxies show CO(3-2) emission also in their disks. The line intensities are higher than that of normal galaxies. This suggests that even if a starburst is a localized phenomenon, it is related to different properties of the molecular gas over the whole galaxy.

Agonist- and Reflex-Evoked Internalization of Metabotropic Glutamate Receptor 5 in Enteric Neurons

We demonstrate that metabotropic glutamate receptor 5 (mGluR5) is present in the guinea pig ileum. A punctate ring-like distribution of immunoreactivity is found on the soma of a subset of neurons, consistent with an association of mGluR5 with the plasma membrane. mGluR5-containing cells in the submucosal plexus are predominantly noncholinergic and contain vasoactive intestinal peptide, a marker of secretomotor neurons. Using immunocytochemistry in conjunction with confocal microscopy, we show that the mGluR5 undergoes agonist- and reflex-evoked internalization that is inhibited by the group I antagonist 1-aminoindan-1,5-dicarboxylic acid. In addition, group I mGluR antagonists reduce the distension-induced phosphorylation of cAMP-responsive element-binding protein in enteric neurons and attenuate both glutamate- and group I agonist-induced depolarizing responses and slow synaptic events in submucosal neurons. These findings support the idea that mGluRs play a role in enteric reflexes and suggest that internalization might be a major mechanism for regulation of mGluR activity.