SYNTHESIS, FREE RADICAL SCAVENGING AND DNA CLEAVAGE ACTIVITIES OF SOME NOVEL INDOLE DERIVATIVES

Objective: Synthesis of a series of novel indole derivatives (6a-h) by condensation of indolyl chalcones (5a-h) with thiobarbituric acid to evaluate free radical scavenging and DNA cleavage activity.Methods: The newly synthesized compounds were screened for free radical scavenging activity by DPPH method. The DNA cleavage activity of some indole derivatives was studied by agarose gel electrophoresis method. The structures of the synthesized compounds are assigned on the basis of elemental analysis, IR, 1HNMR, 13C NMR and mass spectral data.Results: Among the synthesized compounds the simple indole derivative (6a) has very good scavenging activity, chloro and fluoro substituted indole derivatives (6g), (6h) have shown moderate activities and methyl derivatives (6e), (6f) have shown least activity compare with the standard. All the tested compounds in the series have exhibited promising DNA cleavage activity.Conclusion: A series of novel indole derivatives were synthesized and evaluated for free radical scavenging and DNA cleavage activity. The compound (6g) was found most active among all the synthesized compounds.Â

Novel Neuroprotective Function of Apical-Basal Polarity GeneCrumbs in Amyloid Beta 42 (Aβ42) Mediated Neurodegeneration

Alzheimer\u27s disease (AD, OMIM: 104300), a progressive neurodegenerative disorder with no cure to date, is caused by the generation of amyloid-beta-42 (Aβ42) aggregates that trigger neuronal cell death by unknown mechanism(s). We have developed a transgenic Drosophilaeye model where misexpression of human Aβ42 results in AD-like neuropathology in the neural retina. We have identified an apical-basal polarity gene crumbs (crb) as a genetic modifier of Aβ42-mediated-neuropathology. Misexpression of Aβ42 caused upregulation of Crb expression, whereas downregulation of Crb either by RNAi or null allele approach rescued the Aβ42-mediated-neurodegeneration. Co-expression of full length Crb with Aβ42 increased severity of Aβ42-mediated-neurodegeneration, due to three fold induction of cell death in comparison to the wild type. Higher Crb levels affect axonal targeting from the retina to the brain. The structure function analysis identified intracellular domain of Crb to be required for Aβ42-mediated-neurodegeneration. We demonstrate a novel neuroprotective role of Crb in Aβ42-mediated-neurodegeneration

Activation of JNK Signaling Mediates Amyloid-ß-Dependent Cell Death

Alzheimer's disease (AD) is an age related progressive neurodegenerative disorder. One of the reasons for Alzheimer's neuropathology is the generation of large aggregates of Aß42 that are toxic in nature and induce oxidative stress, aberrant signaling and many other cellular alterations that trigger neuronal cell death. However, the exact mechanisms leading to cell death are not clearly understood.We employed a Drosophila eye model of AD to study how Aß42 causes cell death. Misexpression of higher levels of Aß42 in the differentiating photoreceptors of fly retina rapidly induced aberrant cellular phenotypes and cell death. We found that blocking caspase-dependent cell death initially blocked cell death but did not lead to a significant rescue in the adult eye. However, blocking the levels of c-Jun NH(2)-terminal kinase (JNK) signaling pathway significantly rescued the neurodegeneration phenotype of Aß42 misexpression both in eye imaginal disc as well as the adult eye. Misexpression of Aß42 induced transcriptional upregulation of puckered (puc), a downstream target and functional read out of JNK signaling. Moreover, a three-fold increase in phospho-Jun (activated Jun) protein levels was seen in Aß42 retina as compared to the wild-type retina. When we blocked both caspases and JNK signaling simultaneously in the fly retina, the rescue of the neurodegenerative phenotype is comparable to that caused by blocking JNK signaling pathway alone.Our data suggests that (i) accumulation of Aß42 plaques induces JNK signaling in neurons and (ii) induction of JNK contributes to Aß42 mediated cell death. Therefore, inappropriate JNK activation may indeed be relevant to the AD neuropathology, thus making JNK a key target for AD therapies

Titania based nanocomposites as a photocatalyst: A review

Titanium dioxide or Titania is a semiconductor compound having remarkable dielectric, electronic and physico-chemical surface properties. It has excellent photocatalytic efficiency in presence of UV light. The curious grey matter of scientists has forced them to focus their attention to make Titania capable of utilizing the whole visible spectrum of light also. The hurdle that they faced was larger band gap of 3 eV and more, for this, efforts were directed towards adding other materials to Titania. The present article reviews the recent advances in the synthesis of different Titanium-based nanocomposite materials and their photocatalytic efficiency so as to apply them for several applications such as removal of dyes, other water pollutants, microbes and metals. A brief explanation of the photocatalytic process and the structural properties of TiO2 are also touched upon. Various past and recent approaches made in these directions of utilizing Titania based nanocomposites for photocatalytic activities are reviewed. It is suggested that there is a need to establish the kinetics of photo-corrosion and thermodynamic part of the photo-corrosion of various composites developed by different group across the globe, so that Titania based nanocomposites could be commercially utilized

Memcached : An Experimental Study of DDoS Attacks for the Wellbeing of IoT Applications

Distributed denial‐of‐service (DDoS) attacks are significant threats to the cyber world because of their potential to quickly bring down victims. Memcached vulnerabilities have been targeted by attackers using DDoS amplification attacks. GitHub and Arbor Networks were the victims of Memcached DDoS attacks with 1.3 Tbps and 1.8 Tbps attack strengths, respectively. The bandwidth amplification factor of nearly 50,000 makes Memcached the deadliest DDoS attack vector to date. In recent times, fellow researchers have made specific efforts to analyze and evaluate Memcached vulnerabilities; however, the solutions provided for security are based on best practices by users and service providers. This study is the first attempt at modifying the architecture of Memcached servers in the context of improving security against DDoS attacks. This study discusses the Memcached protocol, the vulnerabilities associated with it, the future challenges for different IoT applications associated with caches, and the solutions for detecting Memcached DDoS attacks. The proposed solution is a novel identification‐pattern mechanism using a threshold scheme for detecting volume‐based DDoS attacks. In the undertaken study, the solution acts as a pre‐emptive measure for detecting DDoS attacks while maintaining low latency and high throughput

Modulating <i>crb</i> levels in the Aβ42 background leads to defects in axonal targeting from retina to the brain.

<p>(A) Wild Type eye disc stained with sensory neuron marker, Chaoptin (24B10) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone.0078717-Zipursky1" target="_blank">[34]</a>, which marks only photoreceptor neurons and their axons. The photoreceptor neurons extends through the optic stalk and innervate the medulla and lamina of the larval brain. Note that misexpression of Aβ42 (GMR>Aβ42) in the eye imaginal discs, (B) there is mislocalization of 24B10 expression showing aberrant axonal targeting from retina to brain. The retinal axons fail to innervate the two layers of the brain and end abruptly. (C) Misexpression of Crb full length (FL) in the GMR>Aβ42 background (GMR>Aβ42+Crb FL) strongly enhances the neurodegeneration phenotype which results in (C) lack of axonal targeting from retina to brain. Reducing Crb levels by using (D) <i>crb^11A22</i> allele <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone.0078717-Johnson1" target="_blank">[33]</a> (GMR>Aβ42+<i>crb^11A22</i>) or (E) <i>crb</i> RNAi (VDRC) (GMR>Aβ42+RNAi) result in the significant rescue of GMR>Aβ42 mediated neurodegeneration as evident from the (D, E) restoration of retinal axon targeting.</p

Intracellular domain (ICD) of Crb is required for Aβ42 mediated neurodegeneration.

<p>(A) A cartoon depicting full length type I transmembrane Crb protein and various truncated constructs used in this study. The full length Crb protein consists of an extracellular domain (ECD), transmembrane domain (TM), and a short cytoplasmic intracellular domain (ICD), which consists of the juxtamembrane Ferm-binding motif (JM) and PDZ-binding motif (PBM) domains <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone.0078717-Klebes1" target="_blank">[28]</a>. GMR-Gal4 driver was used for the misexpression studies in the differentiating photoreceptor neurons <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone.0078717-Moses1" target="_blank">[22]</a>. (B–D) Adult eyes of (B) Wild-Type, (C) GMR>Aβ42 (GMR enhancer driving overexpression of human Aβ42 in the developing neural retina), and (D) GMR>Crb (FL) are shown as controls. (A, E–F) Misexpression of (E) Crb^intra alone, comprising of fully intact ICD, shows a severe phenotype with a small scab on the head cuticle in the adult eye, which is similar to the (F) GMR>Aβ42+Crb^intra adult eye. (G) In the GMR>Aβ42+Crb^intra eye disc big gaps and holes between photoreceptors of the ommatidia are seen, Dlg (white) marks the membrane and provide an outline of the imaginal disc and pan neural marker Elav <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone.0078717-Dhanasekaran1" target="_blank">[52]</a> marks the photoreceptors. (A, H–P) In the three other Crb constructs, one of the two domains (JM and PBM) of the ICD is either missing or both of them are missing. (H–P) When Crb is missing either (H–J) PBM, or (K–M) JM, or (N–P) both the PBM and JM domain of the ICD, the GMR>Aβ42 neurodegenerative phenotype is restored significantly with the adult eye having a larger size, higher number of ommatidia, and interommatidial bristles. Furthermore, the Elav staining in the eye-imaginal discs shows more organized photoreceptors in comparison to the GMR>Aβ42 eye imaginal disc. (H, K, N) The controls (H) GMR>Crb^{intra ΔPBM}, (K) GMR>Crb^{intra ΔJM}, and (N) GMR>Crb^{intra ΔPBM ΔJM} showed adult eye phenotypes that are significantly closer to the wild-type. (I, J) When the PBM domain (GMR>Aβ42+Crb^{intra ΔPBM}) is missing, (I) the adult eye and (J) the eye imaginal disc showed significant rescue in comparison to the GMR>Aβ42 phenotype. (L, M) When the JM domain (GMR>Aβ42+Crb^{intra ΔJM}) is missing, (L) the adult eye and (M) the eye-imaginal disc showed significant rescue in comparison to the GMR>Aβ42 phenotype. (O, P) Finally, when both PBM and JM domains of the ICD are missing (GMR>Aβ42+Crb^{intra ΔPBM ΔJM}), a significant rescue was seen in (O) the adult eye and (P) the eye imaginal disc in comparison to the GMR>Aβ42 phenotype.</p

Misexpression of Crb intracellular domain (ICD) can impair axonal targeting.

<p>The eye-antennal disc is stained with Elav (red), which marks the photoreceptors, and 24B10 (chaoptin; green), which stains the axons from the retina to the brain <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone.0078717-Zipursky1" target="_blank">[34]</a>. (A, B) Misexpression of intact instar cellular domain ICD GMR>Aβ42+Crb^intra results in clumping of photoreceptors (Elav; A), disorganization of axonal targeting from the retina to the brain as evident from 24B10 staining. (C, D)When the JM motif using GMR>Aβ42+Crb^{intra ΔJM}, photoreceptor organization as well as the axonal targeting is restored to the wild type. Similarly, removing the (E, F) PBM motif of the ICD using GMR>Aβ42+Crb^{intra ΔPBM}, or both PBM and JM domain in GMR>Aβ42+Crb^{intra ΔJMΔPBM}, result in restoration of axonal targeting and photoreceptors. Thus, ICD domain of Crb is required for its role in neurodegeneration.</p

Downregulation of <i>crb</i> can block neurodegeneration in the Aβ42 background.

<p>TUNEL assays are commonly employed to mark the cells undergoing cell death where the cleavage of double and single stranded DNA is labeled by a Fluorescein <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone.0078717-White1" target="_blank">[31]</a>. (A) Wild type eye imaginal disc showing a few TUNEL positive nuclei. (B) Misexpression of Aβ42 using GMR-Gal4 driver <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone.0078717-Moses1" target="_blank">[22]</a> in the differentiating photoreceptor neurons results in induction of neurodegeneration (B) as seen by a three-fold induction of cell death as evident from number of TUNEL positive nuclei of the dying cells in comparison to (A) wild type eye imaginal disc. Misexpression of Crb full length (FL) in GMR>Aβ42 background (GMR>Aβ42+Crb FL) strongly enhances (C) the neurodegeneration phenotype which results in nearly seven fold increase in number of TUNEL positive nuclei of dying cells in comparison to wild type eye imaginal disc. (D, E) Reducing Crb levels by using (D) <i>crb^11A22</i> mutant allele <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone.0078717-Johnson1" target="_blank">[33]</a> (GMR>Aβ42+<i>crb^11A22</i>) or (E) <i>crb</i> RNAi (VDRC) (GMR>Aβ42+RNAi) result in the rescue of GMR>Aβ42 mediated neurodegeneration as evident from reduction in numbers of TUNEL positive nuclei of the dying cells. (F) Quantitatively, the number of TUNEL cells have been counted and recorded with all five constructs shown. These phenotypes of enhancement of neurodegenerative phenotype and rescue, based on the number of TUNEL positive cells, are significant as seen by the calculation of P-values based on the one-tailed t-test using Microsoft Excel 2010.</p

Misexpression of Crb intracellular domain triggers neuronal cell death.

<p>(A, C, E, G) The eye-antennal discs are stained with pan neural marker Elav (green), marking the photoreceptor neurons, and TUNEL (red), which marks the nuclei of dying cells. (B, D, F, H) The split channels of the TUNEL cells are shown for better depiction of the TUNEL cells alone. (A, B) In the GMR>Aβ42+crb^intra eye disc, the neurodegenerative phenotype of GMR>Aβ42 is enhanced due to increased number of dying photoreceptor neurons as evident from the large number of TUNEL (red) positive cells nuclei, which are (I) calculated quantitatively for all constructs in the bar graph. (A)The dying photoreceptors are clumped and fused together. When we removed either of the PBM, JM or both of these domains within the intracellular domain (ICD) motifs, we see a rescue in the adult eye (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone-0078717-g002" target="_blank">Figure 2</a>) and also a (I) decrease in the number of TUNEL positive cells. (C, D) GMR>Aβ42+Crb^{intra ΔJM} (when the JM motif is removed) shows an increase in the (C) organization of the photoreceptors within the ommatidia (Elav) and (C, D, I) a decrease in the number of TUNEL positive cells nuclei as compared to the GMR>Aβ42+Crb^intra. (D) The number of dying cells in GMR>Aβ42+Crb^{intra ΔJM} is closer to that seen in the wild-type. A similar result was found (E, F, I) when PBM domain was removed from the ICD motif, GMR>Aβ42+Crb^{intra ΔPBM} or (G, H, I) when both the JM and PBM domains were removed from the ICD motif Aβ42+Crb^{intra ΔJM ΔPBM}. In comparison to GMR>Aβ42+Crb^intra, we see a significant decrease in the number of TUNEL positive cells in (E, F, I) GMR>Aβ42+Crb^{intra ΔPBM} and (G, H, I), Aβ42+Crb^{intra ΔJM ΔPBM}. (E–H) The number of dying cell nuclei is closer to that seen in the wild-type. Thus, when the ICD is intact (A, B), there is a large number of TUNEL positive cells, which accounts for the adult eye phenotype observed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078717#pone-0078717-g002" target="_blank">Figure 2B</a>. However, when either or both of the ICD motifs are removed (C, D, E, F, G, H), there is a significant reduction in the number of TUNEL positive cells as compared to GMR>Aβ42+Crb^intra and GMR>Aβ42.</p