A STRIPAK component Strip regulates neuronal morphogenesis by affecting microtubule stability

During neural development, regulation of microtubule stability is essential for proper morphogenesis of neurons. Recently, the striatin-interacting phosphatase and kinase (STRIPAK) complex was revealed to be involved in diverse cellular processes. However, there is little evidence that STRIPAK components regulate microtubule dynamics, especially in vivo. Here, we show that one of the core STRIPAK components, Strip, is required for microtubule organization during neuronal morphogenesis. Knockdown of Strip causes a decrease in the level of acetylated α-tubulin in Drosophila S2 cells, suggesting that Strip influences the stability of microtubules. We also found that Strip physically and genetically interacts with tubulin folding cofactor D (TBCD), an essential regulator of α- and β-tubulin heterodimers. Furthermore, we demonstrate the genetic interaction between strip and Down syndrome cell adhesion molecule (Dscam), a cell surface molecule that is known to work with TBCD. Thus, we propose that Strip regulates neuronal morphogenesis by affecting microtubule stability.This work was supported by grants from the Japanese Ministry of Education, Science, Sports, Culture and Technology (MEXT), the Japan Society for the Promotion of Science and the Japan Science and Technology Agency (to C.S., M.O., M.M. and T.C.)

Embedded Star Clusters in the W51 Giant Molecular Cloud

We present sub-arcsecond (0.35"-0.9"), near-infrared J,H,K band photometric observations of six fields along the W51 Giant Molecular Cloud (W51 GMC). Our observations reveal four new, embedded clusters and provide a new high-resolution (0.35") view of the W51IRS2 (G49.5-0.4) region. The cluster associated with G48.9-0.3 is found to be a double cluster enclosed in a nest of near-infrared nebulosity. We construct stellar surface density maps for four major clusters in the W51 GMC. These unveil the underlying hierarchical structure. Color-color and color-magnitude diagrams for each of these clusters show clear differences in the embedded stellar populations and indicate the relative ages of these clusters. In particular, the clusters associated with the HII regions G48.9-0.3 and G49.0-0.3 are found to have a high fraction of YSOs and are therefore considered the youngest of all the near-infrared clusters in the W51 GMC. The estimated masses of the individual clusters, when summed, yield a total stellar mass of ~10^4 Msun in the W51 GMC, implying a star formation efficiency of 5-10%. These results in comparision with the CO observations of the W51 GMC, suggest for the first time, that star formation in the W51 GMC is likely triggered by a galactic spiral density wave.Comment: 10 pages and 5 figures. 3 figures in jpeg forma

Variability in the stellar initial mass function at low and high mass: 3-component IMF models

Three component models of the IMF are made to consider possible origins for the observed relative variations in the numbers of brown dwarfs, solar-to-intermediate mass stars, and high mass stars. Three distinct physical processes are noted. The characteristic mass for most star formation is identified with the thermal Jeans mass in the molecular cloud core, and this presumably leads to the middle mass range by the usual collapse and accretion processes. Pre-stellar condensations (PSCs) observed in mm-wave continuum studies presumably form at this mass. Significantly smaller self-gravitating masses require much larger pressures and may arise following dynamical processes inside these PSCs, including disk formation, tight-cluster ejection, and photoevaporation as studied elsewhere, but also gravitational collapse of shocked gas in colliding PSCs. Significantly larger stellar masses form in relatively low abundance by normal cloud processes, possibly leading to steep IMFs in low-pressure field regions, but this mass range can be significantly extended in high pressure cloud cores by gravitationally-focussed gas accretion onto PSCs and by the coalescence of PSCs. These models suggest that the observed variations in brown dwarf, solar-to-intermediate mass, and high mass populations are the result of dynamical effects that depend on environmental density and velocity dispersion. They accommodate observations ranging from shallow IMFs in cluster cores to Salpeter IMFs in average clusters and whole galaxies to steep and even steeper IMFs in field and remote field regions. They also suggest how the top-heavy IMFs in some starburst clusters may originate and they explain bottom-heavy IMFs in low surface brightness galaxies.Comment: 10 pages, 2 figures, accepted by Monthly Notices of the Royal Astronomical Societ

CHEMICAL LEUKODERMA: WHAT’S NEW ON ETIOPATHOLOGICAL AND CLINICAL ASPECTS?

Chemical leukoderma denotes an acquired hypopigmentation caused by repeated exposure to specific chemical compounds simulating clinically idiopathic vitiligo. The ailment has been increasing in developing countries like India in recent years. Etiologically, a lot of chemicals, especially phenolic group, have been identified in various countries including India. The term, “chemical leukoderma syndrome” has been described to encompass all the various manifestations of chemical leukoderma. Clinical diagnostic criteria have been proposed to diagnose chemical leukoderma clinically more confidently

CHEMICAL LEUCODERMA: INDIAN SCENARIO, PROGNOSIS, AND TREATMENT

Chemical leucoderma is an industrial disorder in developed countries and the common causative chemicals are phenols and catechols. Due to stringent controls and preventive measures the incidence has come down. In the recent past various chemicals in consumer products have also been documented to produce depigmentation. In India due to lax quality control measures chemical leucoderma due to consumer items is not uncommon.The various consumer items documented to cause contact depigmentation are sticker bindis, rain shoes, plastic chappals, hair dye/ black henna(kali mehndi), alta, wallets and even mobile plastic covers