Directional transport and active retention of Dpp/BMP create wing vein patterns in Drosophila

AbstractThe bone morphogenetic protein (BMP) family ligand decapentaplegic (Dpp) plays critical roles in wing vein development during pupal stages in Drosophila. However, how the diffusible Dpp specifies elaborate wing vein patterns remains unknown. Here, we visualized Dpp distribution in the pupal wing and found that it tightly reflects the wing vein patterns. We show that Dpp is directionally transported from the longitudinal veins (LVs) into the posterior crossvein (PCV) primordial region by the extracellular BMP-binding proteins, short gastrulation (Sog) and crossveinless (Cv). Another BMP-type ligand, glass bottom boat (Gbb), also moves into the PCV region and is required for Dpp distribution, presumably as a Dpp–Gbb heterodimer. In contrast, we found that most of the Dpp is actively retained in the LVs by the BMP type I receptor thickveins (Tkv) and a positive feedback mechanism. We provide evidence that the directionality of Dpp transport is manifested by sog transcription that prepatterns the PCV position in a Dpp signal-independent manner. Taken together, our data suggest that spatial distribution of Dpp is tightly regulated at the extracellular level by combination of long-range facilitated transport toward the PCV and short-range signaling by active retention in the LVs, thereby allowing diffusible ligands to form elaborate wing vein patterns

Time-domain Brillouin scattering assisted by diffraction gratings

Absorption of ultrashort laser pulses in a metallic grating deposited on a transparent sample launches coherent compression/dilatation acoustic pulses in directions of different orders of acoustic diffraction. Their propagation is detected by the delayed laser pulses, which are also diffracted by the metallic grating, through the measurement of the transient intensity change of the first order diffracted light. The obtained data contain multiple frequency components which are interpreted by considering all possible angles for the Brillouin scattering of light achieved through the multiplexing of the propagation directions of light and coherent sound by the metallic grating. The emitted acoustic field can be equivalently presented as a superposition of the plane inhomogeneous acoustic waves, which constitute an acoustic diffraction grating for the probe light. Thus, the obtained results can also be interpreted as a consequence of probe light diffraction by both metallic and acoustic gratings. The realized scheme of time-domain Brillouin scattering with metallic grating operating in reflection mode provides access to acoustic frequencies from the minimal to the maximal possible in a single experimental configuration for the directions of probe light incidence and scattered light detection. This is achieved by monitoring of the backward and forward Brillouin scattering processes in parallel. Applications include measurements of the acoustic dispersion, simultaneous determination of sound velocity and optical refractive index, and evaluation of the samples with a single direction of possible optical access.Comment: 21 pages, 4 figures, 1 tabl

Mapping the band structure of a surface phononic crystal

We map the band structure of surface acoustic modes of a periodic array of copper lines embedded in a SiO2 film on a silicon substrate by means of the laser-induced transient grating technique. A detailed map of the lowest sheet of the ω(k) surface and partial maps of two higher-order sheets are obtained. We discuss the topology of the ω(k) surface and explain how it arises from the Rayleigh and Sezawa modes of the film/substrate system. In the vicinity of the bandgap formed at the Brillouin zone boundary, the first and second dispersion sheets take the form of a saddle and a bowl, respectively, in agreement with a weak perturbation model. The shape of the third dispersion sheet, however, appears to defy expectations based on the perturbation approach. In particular, it contains minima located off the symmetry directions, which implies the existence of zero group velocity modes with an obliquely directed wavevector.United States. Dept. of Energy (Office of Science, and Office of Basic Energy Sciences, S3TEC Energy Frontier Research Center under award no. DE-SC0001088

Kainic acid induces expression of caveolin-1 in activated microglia in rat brain

Caveolin-1, a major constituent of caveolae, has been implicated in endocytosis, signal transduction and cholesterol transport in a wide variety of cells. In the present study, the expression of caveolin-1 was examined by immunohistochemistry in rat brain with or without systemic injection of kainic acid (KA). Caveolin-1 immunoreactivity was observed in capillary walls in brains of control rats. From one to seven days after KA injection, caveolin-1 immunoreactivity appeared in activated microglia in the cerebral cortex, hippocampus and other brain regions. The strongest immunoreactivity of microglia was seen after 3 days after KA administration. The expression of caveolin-1 was confirmed by RT-PCR and Western blot analysis, respectively. The induction of caveolin-1 expression in microglia activated in response to kainic acid administration suggests its possible role in a modulation of inflammation. (Folia Histochemica et Cytobiologica 2013, Vol. 51, No. 1, 25–30

Gliding Basal Cell Migration of the Urothelium during Wound Healing

Collective cell migration during wound healing has been extensively studied in the epidermis. However, it remains unknown whether the urothelium repairs wounds in a manner similar to the epidermis. By in vivo two-photon excitation microscopy of transgenic mice that express fluorescent biosensors, we studied the collective cell migration of the urothelium in comparison with that of the epidermis. In vivo time-lapse imaging revealed that, even in the absence of a wound, urothelial cells continuously moved and sometimes glided as a sheet over the underlying lamina propria. On abrasion of the epithelium, the migration speed of each epidermal cell was inversely correlated with the distance to the wound edge. Repetitive activation waves of extracellular signal–regulated kinase (ERK) were generated at and propagated away from the wound edge. In contrast, urothelial cells glided as a sheet over the lamina propria without any ERK activation waves. Accordingly, the mitogen-activated protein kinase/ERK kinase inhibitor PD0325901 decreased the migration velocity of the epidermis but not the urothelium. Interestingly, the tyrosine kinase inhibitor dasatinib inhibited migration of the urothelium as well as the epidermis, suggesting that the gliding migration of the urothelium is an active, not a passive, migration. In conclusion, the urothelium glides over the lamina propria to fill wounds in an ERK-independent manner, whereas the epidermis crawls to cover wounds in an ERK-dependent manner

Electrolyte composition of renal tubular cells in gentamicin nephrotoxicity

Electrolyte composition of renal tubular cells in gentamicin nephrotoxicity. The effect of long-term gentamicin administration on sodium, potassium, chloride and phosphorus concentrations was studied in individual rat renal tubular cells using electron microprobe analysis. Histological damage was apparent only in proximal tubular cells. The extent of damage was only mild after 7 days of gentamicin administration (60 mg/kg body wt/day) but much more pronounced after 10 days. GFR showed a progressive decline during gentamicin treatment. In non-necrotic proximal tubular cells, sodium was increased from 14.6 ± 0.3 (mean ± SEM) in controls to 20.6 ± 0.4 after 7 and 22.0 ± 0.8 mmol/kg wet wt after 10 days of gentamicin administration. Chloride concentration was higher only after 10 days (20.6 ± 0.6 vs. 17.3 ± 0.2 mmol/kg wet wt). Both cell potassium and phosphorus concentrations were diminished by 6 and 15, and by 8 and 25 mmol/kg wet wt after 7 and 10 days of treatment, respectively. In contrast, no major alterations in distal tubular cell electrolyte concentrations could be observed after either 7 or 10 days of gentamicin administration. As in proximal tubular cells, distal tubular cell phosphorus concentrations were, however, lowered by gentamicin treatment. These results clearly indicate that gentamicin exerts its main effect on proximal tubular cells. Decreased potassium and increased sodium and chloride concentrations were observed in proximal tubular cells exhibiting only mild histological damage prior to the onset of advanced tissue injury. Necrotic cells, on the other hand, showed widely variable intracellular electrolyte concentration patterns

Confirmation of a one-dimensional spin-1/2 Heisenberg system with ferromagnetic first-nearest-neighbor and antiferromagnetic second-nearest-neighbor interactions in Rb2{}_{2}Cu2{}_{2}Mo3{}_{3}O12{}_{12}

We have investigated magnetic properties of Rb$_2$Cu$_2$Mo$_3$O$_{12}$ powder. Temperature dependence of magnetic susceptibility and magnetic-field dependence of magnetization have shown that this cuprate is a model compound of a one-dimensional spin-1/2 Heisenberg system with ferromagnetic first-nearest-neighbor (1NN) and antiferromagnetic second-nearest-neighbor (2NN) competing interactions (competing system). Values of the 1NN and 2NN interactions are estimated as $J_1 = -138$ K and $J_2 = 51$ K ($\alpha \equiv J_2 / J_1 = -0.37$). This value of $\alpha$ suggests that the ground state is a spin-singlet incommensurate state. In spite of relatively large $J_1$ and $J_2$, no magnetic phase transition appears down to 2 K, while an antiferromagnetic transition occurs in other model compounds of the competing system with ferromagnetic 1NN interaction. For that reason, Rb$_2$Cu$_2$Mo$_3$O$_{12}$ is an ideal model compound to study properties of the incommensurate ground state that are unconfirmed experimentally.Comment: 6 pages, 4 figure