Domain swapping in human αA and αB crystallins affects oligomerization and enhances chaperone-like activity

αA and αB crystallins, members of the small heat shock protein family, prevent aggregation of proteins by their chaperone-like activity. These two proteins, although very homologous, particularly in the C-terminal region, which contains the highly conserved "α-crystallin domain," show differences in their protective ability toward aggregation-prone target proteins. In order to investigate the differences between αA and αB crystallins, we engineered two chimeric proteins, αANBC and αBNAC, by swapping the N-terminal domains of αA and αB crystallins. The chimeras were cloned and expressed in Escherichia coli. The purified recombinant wild-type and chimeric proteins were characterized by fluorescence and circular dichroism spectroscopy and gel permeation chromatography to study the changes in secondary, tertiary, and quaternary structure. Circular dichroism studies show structural changes in the chimeric proteins. αBNAC binds more 8-anilinonaphthalene-1-sulfonic acid than the αANBC and the wild-type proteins, indicating increased accessible hydrophobic regions. The oligomeric state of αANBC is comparable to wild-type αB homoaggregate. However, there is a large increase in the oligomer size of the αBNAC chimera. Interestingly, swapping domains results in complete loss of chaperone-like activity of αANBC, whereas αBNAC shows severalfold increase in its protective ability. Our findings show the importance of the N- and C-terminal domains of αA and αB crystallins in subunit oligomerization and chaperone-like activity. Domain swapping results in an engineered protein with significantly enhanced chaperone-like activity

Morpho-anatomical responses of Catharanthus roseus due to combined heavy metal stress observed under Scanning Electron Microscope

Heavy metals trigger various plant responses that basically vary with the intensity as well as duration of stress. Comprehension of the morphological and anatomical responses to such stress is essential for a holistic perception of plant resistance mechanisms to metal-excess conditions in higher plants. In the present study, the effects of heavy metals on morpho-anatomy of Catharanthus roseus based on its potential to tolerate metal stress has been studied in industrially polluted environments. The tissue samples of these plants grown in contaminated and uncontaminated soils were processed for analysis under Scanning Electron Microscope (SEM). Briefly, harvested tissues were pre-fixed using glutaraldehyde and paraformaldehyde in sodium cacodylate (CAC) buffer, followed by post fixation in osmium tetroxide. Further, the digital micrographs of critically dried samples were captured. The analysis of micrographs revealed structural changes like cell wall thickening, increased stele diameter, increased root and shoot diameter, variations in stomatal number, enlargement of trichomes and salt glands of plants grown in contaminated soil when compared to those grown in uncontaminated soil. The study also provided microscopic evidence of endophytic colonization of microorganisms within surface-disinfected plant tissues. Based on the varied morpho-anatomical responses due to heavy metal stress, several physiological and metabolic mechanisms of plants were deciphered

Effect of Substrates Types on CO Gas Sensing of SnO2 Thin Film Prepared by Sol-Gel Method

Tin oxide thin film was synthesized on glass and quartz substrate by sol-gel dip coating process taking tin (II) chloride as precursor and methanol as solvent. XRD study confirmed the tetragonal rutile structure of SnO2. It was concluded that the transmission was higher and grain size was bigger in case of quartz than glass substrate from the study of optical characteristics by UV/VIS Spectrophotometer and SEM micrographs. CO gas sensing property of SnO2 thin film was studied and it was revealed that the sensitivity of SnO2 thin film grown on quartz substrate shows better performance than the film grown on glass substrate under the same conditions. Sensitivity of the film to CO gas was measured at different temperatures and was found to be highly sensitive at 220 C for glass substrate and 210 C for quartz substrate, at 50 ppm concentration. The result of change in conductivity of the sensors in presence of CO gas was also reported. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3554

Comparative Analysis of QoS-Aware Routing Protocols for Wireless Sensor Networks

The main ability of wireless sensor networks (WSNs) is communicating and sensing between nodes, which are deployed in a wide area with a large number of nodes. Wireless sensor networks are composed of a large number of sensor nodes with limited energy resources. One critical issue in wireless sensor networks is how to gather sensed information in an energy efficient way, since their energy is limited. The limiting factors of the sensor nodes, such as their finite energy supplies and their moderate processing abilities, as well as the unreliable wireless medium restrict the performance of wireless sensor networks While contemporary best-effort routing approaches address unconstrained traffic, QoS routing is usually performed through resource reservation in a connection-oriented communication in order to meet the QoS requirements for each individual connection. This article surveys a sample of existing QoS-Aware Routing Protocols for Wireless Sensor Networks and highlights their key features, including merits and limitations. Keywords: Wireless sensor networks, Routing protocols, QoS-Aware Routing Protocols

Preemptive Routing & Intrusion Detection for MANETs

An ad-hoc network will often change rapidly in topology, this courses for routes in the network to often disappear and new to arise. The Ad-hoc On-Demand Distance Vector Routing Protocol(AODV), is based on the principle of discover routes as needed. In this paper we will extend the definition of AODV with the ability to discover multiple routes to a host and switch between them, if an active route is becoming weak and there is a risk that it will disappear. We will refer to it as pre-emptive AOMDV . We will show that the performance of pre-emptive AOMDV do handle changes in topology better than AODV it self. To show the effect of extending AODV, the suggested protocol is implemented in a simulator. Performance enhancements will be presented from different scenarios, to compare pre-emptive AOMDV with the ordinary AODV. In this paper we also focus on intrusion detection based on Finite State Machine and cache memory in ad hoc networks. Security is one of the most important issues in current networks. The most common cases of attacks in mobile Ad hoc networks can be drop of routing packets and changes in the incoming packets which aims at disrupting the network routing and overall network reduce performance. The presented approach based on FSM focuses at recognizing the malicious nodes within the network in a fast and accurate way, then it deals with rapid introduction of the malicious nodes to other nodes in the network to prevent sending multiple packets and drop and packet change. Finally, we will show the significant improvement in comparison with others, we simulated our methods by NS2 software

Redox-regulated chaperone function and conformational changes of Escherichia coli Hsp33

We have studied the chaperone activity and conformation of Escherichia coli heat shock protein (Hsp)33, whose activity is known to be switched on by oxidative conditions. While oxidized Hsp33 completely prevents the heat-induced aggregation of ζ-crystallin at 42°C at a ratio of 1:1 (w/w), the reduced form exhibits only a marginal effect on the aggregation. Far UV–circular dichroism (CD) spectra show that reduced Hsp33 contains a significant α-helical component. Oxidation results in significant changes in the far UV–CD spectrum. Near UV–CD spectra show changes in tertiary structural packing upon oxidation. Polarity-sensitive fluorescent probes report enhanced hydrophobic surfaces in the oxidized Hsp33. Our studies show that the oxidative activation of the chaperone function of Hsp33 involves observable conformational changes accompanying increased exposure of hydrophobic pockets