The myogenic precursors responsible for muscle growth in amniotes develop from the dermomyotome, an epithelium at the external surface of the somite. In teleosts, the myogenic precursors responsible ...for growth have not been identified. We have used single cell lineage labeling in zebrafish to show that anterior border cells of epithelial somites are myogenic precursors responsible for zebrafish myotome growth. These cells move to the external surface of the embryonic myotome and express the transcription factor Pax7. Some remain on the external surface and some incorporate into the fast myotome, apparently by moving between differentiated slow fibres. The posterior cells of the somite, by contrast, elongate into medial muscle fibres. The surprising movement of the anterior somite cells to the external somite surface transforms a segmentally repeated arrangement of myogenic precursors into a medio-lateral arrangement similar to that seen in amniotes.
Abstract We compare the molecular cloud properties in subgalactic regions of two galaxies, barred spiral NGC 1313, which is forming many massive clusters, and flocculent spiral NGC 7793, which is ...forming significantly fewer massive clusters despite having a similar star formation rate to NGC 1313. We find that there are larger variations in cloud properties between different regions within each galaxy than there are between the galaxies on a global scale, especially for NGC 1313. There are higher masses, line widths, pressures, and virial parameters in the arms of NGC 1313 and the center of NGC 7793 than in the interarm and outer regions of the galaxies. The massive cluster formation of NGC 1313 may be driven by its greater variation in environment, allowing more clouds with the necessary conditions to emerge, although no one parameter seems primarily responsible for the difference in star formation. Meanwhile NGC 7793 has clouds that are as massive and have as much kinetic energy as the clouds in the arms of NGC 1313, but have densities and pressures more similar to those in the interarm regions and so are less inclined to collapse and form stars. The cloud properties in NGC 1313 and NGC 7793 suggest that spiral arms, bars, interarm regions, and flocculent spirals each represent distinct environments with regard to molecular cloud populations. We see surprisingly little difference in surface density between the regions, suggesting that the differences in surface densities frequently seen between arm and interarm regions in lower-resolution studies are indicative of the sparsity of molecular clouds, rather than differences in their true surface density.
Abstract We present a comparative study of the molecular gas in two galaxies from the Legacy ExtraGalactic UV Survey (LEGUS) sample: barred spiral NGC 1313 and flocculent spiral NGC 7793. These two ...galaxies have similar masses, metallicities, and star formation rates, but NGC 1313 is forming significantly more massive star clusters than NGC 7793, especially young massive clusters (<10 Myr, >10 4 M ⊙ ). Using Atacama Large Millimeter/submillimeter Array (ALMA) CO(2–1) observations of the two galaxies with the same sensitivity and resolution (13 pc), we directly compare the molecular gas in these two similar galaxies to determine the physical conditions responsible for their large disparity in cluster formation. By fitting size–line width relations for the clouds in each galaxy, we find that NGC 1313 has a higher intercept than NGC 7793, implying that its clouds have higher kinetic energies at a given size scale. NGC 1313 also has more clouds near virial equilibrium than NGC 7793, which may be connected to its higher rate of massive cluster formation. However, these virially bound clouds do not show a stronger correlation with young clusters than with the general cloud population. We find surprisingly small differences between the distributions of molecular cloud populations in the two galaxies, though the largest of those differences is that NGC 1313 has higher surface densities and lower freefall times.
With >80 million United States households engaged in lawn and gardening activities, increasing sustainability of lawn care is important. Mowing height is an easily manipulated aspect of lawn ...management. We tested the hypothesis that elevated mowing of tall fescue lawn grass promotes a larger, more diverse community of arthropod natural enemies which in turn provides stronger biological control services, and the corollary hypothesis that doing so also renders the turf itself less suitable for growth of insect pests. Turf-type tall fescue was mowed low (6.4 cm) or high (10.2 cm) for two growing seasons, natural enemy populations were assessed by vacuum sampling, pitfall traps, and ant baits, and predation and parasitism were evaluated with sentinel prey caterpillars, grubs, and eggs. In addition, foliage-feeding caterpillars and root-feeding scarab grubs were confined in the turf to evaluate their performance. Although some predatory groups (e.g., rove beetles and spiders) were more abundant in high-mowed grass, predation rates were uniformly high because ants, the dominant predators, were similarly abundant regardless of mowing height. Lower canopy temperatures in high-mowed grass were associated with slower growth of grass-feeding caterpillars. Higher lawn mowing reduces fuel consumption and yard waste, and promotes a deep, robust root system that reduces need for water and chemical inputs. Although in this study elevated mowing height did not measurably increase the already-high levels of predation, it did suggest additional ways through which bottom-up effects on insect pest growth might interact with natural enemies to facilitate conservation biological control.
Many golf courses are converting out-of-play areas to meadow-like habitat to reduce mowing, irrigation, and chemical inputs. Such naturalized roughs, which often constitute 50Â % or more of a ...courseâs total acreage, support biodiversity by providing habitat for pollinators and other wildlife. This study explored the hypothesis that they also serve as reservoirs of invertebrate natural enemies whose services extend to suppress pests in adjacent mowed turf. We used vacuum sampling, pitfall traps, and ant baits to compare arthropod populations in grassland or meadow-type naturalized roughs and traditional mowed roughs at two courses, and tested for spillover of biological control using sentinel eggs or larvae of a grass-feeding caterpillar exposed near or farther from naturalized areas into mowed turf. Although some natural enemies (e.g., spiders) were more abundant in naturalized roughs, we saw no direct spillover of predation which was quite high regardless of habitat type. Most likely that is because ground-nesting ants (Lasius, Solenopsis, and Pheidole spp.), which are dominant predators in this system, were equally or more abundant in the mowed turfgrass. Herbivorous insects, too, were more abundant in naturalized roughs, so prey availability may discourage solitary ground-dwelling predators from leaving those refuges to forage in mowed areas. There was no parasitism of sentinel eggs or larvae in our trials. Despite absence of direct spillover of predation, we argue that naturalized roughs might be more purposely designed and managed to promote parasitoids, insectivorous birds, and other enemies that provide diffuse biological control services elsewhere on the course.
Erectile dysfunction (ED) is a significant health concern that greatly impacts quality of life, and is common in men as they age, impacting 52% of men between the ages of 40 and 70. A significant ...underlying cause of ED development is injury to the cavernous nerve (CN), a peripheral nerve that innervates the penis. CN injury also occurs in up to 82% of prostatectomy patients. We recently showed that Sonic hedgehog (SHH) protein delivered by peptide amphiphile (PA) nanofiber hydrogel to the CN and penis of a prostatectomy model of CN injury, is neuroprotective, accelerates CN regeneration, improves erectile function ~60%, preserves penile smooth muscle 56% and suppresses collagen deposition 30%. This regenerative potential is substantial in an adult prostatectomy model (P120). However prostatectomy patients are typically older (61.5 ± 9.6 years) and our models should mimic patient conditions more effectively when considering translation. In this study we examine regenerative potential in an aged prostatectomy model (P200–329).
The caudal portion of the pelvic ganglia (MPG) and CN were dissected from adult (n = 11), and aged (n = 13) Sprague Dawley rats, and were grown in organ culture 3 days. Uninjured and 2 day CN crushed MPG/CN were exposed to Affi-Gel beads containing SHH protein, PBS (control), or 5e1 SHH inhibitor. Neurites were quantified by counting the number of growth cones normalized by tissue perimeter (mm) and immunohistochemistry for SHH, patched1 (PTCH1), smoothened (SMO), GLI1-3, and GAP43 were performed.
SHH treatment increased neurites 3.5-fold, in uninjured adult, and 5.7-fold in aged rats. Two days after CN crush, SHH treatment increased neurites 1.8-fold in adult rats and 2.5-fold in aged rats. SHH inhibition inhibited neurite formation in uninjured MPG/CN but not in 2 day CN crushed MPG/CN. PTCH1 and SMO (SHH receptors), and SHH transcriptional activators/repressors, GLI1-3, were abundant in aged MPG/CN with unaltered localization. ROCK1 was induced with SHH treatment.
Reintroduction of SHH protein in an aged prostatectomy model is even more effective in promoting neurite formation/CN regeneration than in the adult. The first 48 h after CN injury are a critical window when growth factors are released, that impact later neurite formation. These studies are significant because most prostatectomy patients are not young and healthy, as with adult rats, so the aged prostatectomy model will more accurately simulate ED patient response. Understanding how neurite formation changes with age is critical for clinical translation of SHH PA to prostatectomy patients.
•SHH protein is more effective in promoting neurite formation/CN regeneration in aged rats than in the adult.•The first 48 h after CN injury are a critical window when growth factors are released, that impact later neurite formation.•SHH pathway signaling machinery remains intact in aged MPG/CN and are able to respond to exogenous SHH protein.•These studies are significant because the aged prostatectomy model will more accurately simulate ED patient response.•Understanding how neurite formation changes with age is critical for clinical translation of SHH PA to prostatectomy patients
Erectile dysfunction (ED) critically impacts quality of life in prostatectomy, diabetic and aging patients. The underlying mechanism involves cavernous nerve (CN) damage, resulting in ED in 80% of ...prostatectomy patients. Peptide amphiphile (PA) nanofiber hydrogel delivery of sonic hedgehog (SHH) protein to the injured CN, improves erectile function by 60% at 6 weeks after injury, by an unknown mechanism. We hypothesize that SHH is a regulator of neurite formation. SHH treatment promoted extensive neurite formation in uninjured and crushed CNs, and SHH inhibition decreased neurites >80%. Most abundant neurites were observed with continuous SHH PA treatment of crushed CNs. Once induced with SHH, neurites continued to grow. SHH rescued neurite formation when not given immediately. SHH is a critical regulator of neurite formation in peripheral neurons under uninjured and regenerative conditions, and SHH PA treatment at the time of injury/prostatectomy provides an exploitable avenue for intervention to prevent ED.
Erectile dysfunction critically impacts quality of life in prostatectomy, diabetic and aging patients. The underlying mechanism involves cavernous nerve injury. As a step towards clinical translation, we examined how peptide amphiphile nanofiber hydrogels delivering sonic hedgehog protein to the cavernous nerve at the time of crush injury (rat prostatectomy model) significantly promote regeneration and improve erectile function. A key mechanism is sonic hedgehog regulation of neurite formation in penile projecting neurons, which is critical for re-innervation and clinical translation. Development of peptide amphiphile sonic hedgehog delivery has significant potential for high impact on future treatment of prostatectomy patients to prevent erectile dysfunction. Display omitted
A salient effect of addictive drugs is to hijack the dopamine reward system, an evolutionarily conserved driver of goal-directed behavior and learning. Reduced dopamine type 2 receptor availability ...in the striatum is an important pathophysiological mechanism for addiction that is both consequential and causal for other molecular, cellular, and neuronal network differences etiologic for this disorder. Here, we sought to identify gene expression changes attributable to innate low expression of the Drd2 gene in the striatum and specific to striatal indirect medium spiny neurons (iMSNs).
Cre-conditional, translating ribosome affinity purification (TRAP) was used to purify and analyze the translatome (ribosome-bound messenger RNA) of iMSNs from mice with low/heterozygous or wild-type Drd2 expression in iMSNs. Complementary electrophysiological recordings and gene expression analysis of postmortem brain tissue from human cocaine users were performed.
Innate low expression of Drd2 in iMSNs led to differential expression of genes involved in GABA (gamma-aminobutyric acid) and cAMP (cyclic adenosine monophosphate) signaling, neural growth, lipid metabolism, neural excitability, and inflammation. Creb1 was identified as a likely upstream regulator, among others. In human brain, expression of FXYD2, a modulatory subunit of the Na/K pump, was negatively correlated with DRD2 messenger RNA expression. In iMSN-TRAP-Drd2HET mice, increased Cartpt and reduced S100a10 (p11) expression recapitulated previous observations in cocaine paradigms. Electrophysiology experiments supported a higher GABA tone in iMSN-Drd2HET mice.
This study provides strong molecular evidence that, in addiction, inhibition by the indirect pathway is constitutively enhanced through neural growth and increased GABA signaling.
Simple and efficient: Protonation of Ru(1,2:5,6‐η‐cod)(η6‐cot) (cod=1,5‐cyclooctadiene, cot=1,3,5‐cyclooctatriene) with HBF4⋅Et2O and then reaction with chiral bisphosphane ligands ($_{\rm ...PP}^{\frown }$=Me‐DuPHOS, BINAP, Tol‐BINAP, JOSIPHOS) affords the corresponding Ru($_{\rm PP}^{\frown }$)(H)(η6‐cot)+ or Ru($_{\rm PP}^{\frown }$)(1,2,3,4,5‐η‐C8H11′)+ (C8H11′=2,4‐cyclooctadienyl; see scheme). Exposure of these cations to H2 in solvents (sol) such as acetone, methanol, and THF affords Ru($_{\rm PP}^{\frown }$)(H)(sol)3+, which are catalysts for (amongst other things) enantioselective hydrogenations of alkenes.
In this paper we introduce the concept of what we call “NUDAR” (NeUtrino Direction and Ranging), making the point that measurements of the observed energy and direction vectors can be employed to ...passively deduce the exact three-dimensional location and thermal power of geophysical and anthropogenic neutrino sources from even a single detector. Earlier studies have presented the challenges of long-range detection, dominated by the unavoidable inverse-square falloff in neutrinos, which force the use of kiloton scale detectors beyond a few kilometers. Earlier work has also presented the case for multiple detectors, and has reviewed the background challenges. We present the most precise background estimates to date, all handled in full three dimensions, as functions of depth and geographical location. For the present calculations, we consider a hypothetical 138 kiloton detector which can be transported to an ocean site and deployed to an operational depth. We present a Bayesian estimation framework to incorporate any a priori knowledge of the reactor that we are trying to detect, as well as the estimated uncertainty in the background and the oscillation parameters. Most importantly, we fully employ the knowledge of the reactor spectrum and the distance-dependent effects of neutrino oscillations on such spectra. The latter, in particular, makes possible determination of range from one location, given adequate signal statistics. Further, we explore the rich potential of improving detection with even modest improvements in individual neutrino direction determination. We conclude that a 300 MWth reactor can indeed be geolocated, and its operating power estimated with one or two detectors in the hundred kiloton class at ranges out to a few hundred kilometers. We note that such detectors would have natural and non-interfering utility for scientific studies of geo-neutrinos, neutrino oscillations, and astrophysical neutrinos. This motivates the development of cost effective methods of constructing and deploying such next generation detectors.
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