Drosophila neuroglian: a member of the immunoglobulin superfamily with extensive homology to the vertebrate neural adhesion molecule L1

Drosophila neuroglian is an integral membrane glycoprotein that is expressed on a variety of cell types in the Drosophila embryo, including expression on a large subset of glial and neuronal cell bodies in the central and peripheral nervous systems and on the fasciculating axons that extend along them. Neuroglian cDNA clones were isolated by expression cloning. cDNA sequence analysis reveals that neuroglian is a member of the immunoglobulin superfamily. The extracellular portion of the protein consists of six immunoglobulin C2-type domains followed by five fibronectin type III domains. Neuroglian is closely related to the immunoglobulin-like vertebrate neural adhesion molecules and, among them, shows most extensive homology to mouse L1. Its homology to L1 and its embryonic localization suggest that neuroglian may play a role in neural and glial cell adhesion in the developing Drosophila embryo. We report here on the identification of a lethal mutation in the neuroglian gene.     

Helix packing moments reveal diversity and conservation in membrane protein structure

Helical membrane proteins are more tightly packed and the packing interactions are more diverse than those found in helical soluble proteins. Based on a linear correlation between amino acid packing values and interhelical propensity, we propose the concept of a helix packing moment to predict the orientation of helices in helical membrane proteins and membrane protein complexes. We show that the helix packing moment correlates with the helix interfaces of helix dimers of single pass membrane proteins of known structure. Helix packing moments are also shown to help identify the packing interfaces in membrane proteins with multiple transmembrane helices, where a single helix can have multiple contact surfaces. Analyses are described on class A G protein-coupled receptors (GPCRs) with seven transmembrane helices. We show that the helix packing moments are conserved across the class A family of GPCRs and correspond to key structural contacts in rhodopsin. These contacts are distinct from the highly conserved signature motifs of GPCRs and have not previously been recognized. The specific amino acid types involved in these contacts, however, are not necessarily conserved between subfamilies of GPCRs, indicating that the same protein architecture can be supported by a diverse set of interactions. In GPCRs, as well as membrane channels and transporters, amino acid residues with small side-chains (Gly, Ala, Ser, Cys) allow tight helix packing by mediating strong van der Waals interactions between helices. Closely packed helices, in turn, facilitate interhelical hydrogen bonding of both weakly polar (Ser, Thr, Cys) and strongly polar (Asn, Gln, Glu, Asp, His, Arg, Lys) amino acid residues. We propose the use of the helix packing moment as a complementary tool to the helical hydrophobic moment in the analysis of transmembrane sequences.     

Covalent carcinogenic O6-methylguanosine lesions in DNA. Structural studies of the O6 meG X A and O6meG X G interactions in dodecanucleotide duplexes

High-resolution proton and phosphorus nuclear magnetic resonance studies are reported on the self-complementary d(C1-G2-N3-G4-A5-A6-T7-T8-C9-O6meG10-C11-G12) duplexes (henceforth called O6meG X A 12-mer when N3 = A3 and O6meG X G 12-mer when N3 = G3), which contain symmetry-related A3 X O6meG10 and G3 X O6meG10 interactions in the interior of the helices. We observe inter-base-pair nuclear Overhauser effects (NOE) between the base protons at the N3 X O6meG10 modification site and protons of flanking G2 X C11 and G4 X C9 base-pairs, indicative of the stacking of N3 and O6meG10 bases in both O6meG X A 12-mer and O6meG X G 12-mer duplexes. We have assigned all the base and a majority of the sugar protons from two-dimensional proton-correlated and nuclear Overhauser effect experiments on the O6meG X A 12-mer duplex and O6meG X G 12-mer duplex in solution. The observed NOEs establish that the A3 and O6meG10 at the modification site and all other residues adopt the anti configuration about the glycosidic bond, and that the O6meG X A 12-mer forms a right-handed duplex. The interaction between the bulky purine A3 and O6meG10 residues in the anti orientation results in large proton chemical shift perturbations at the (G2-A3-G4) X (C9-O6meG10-C11) segments of the helix. By contrast, we demonstrate that the O6meG10 residue adopts a syn configuration, while all other bases adopt an anti configuration about the glycosidic bond in the right-handed O6meG X G 12-mer duplex. This results in altered NOE patterns between the base protons of O6meG10 and the base and sugar protons of flanking C9 and C11 residues in the O6meG X G 12-mer duplex. The phosphorus backbone is perturbed at the modification site in both duplexes, since the phosphorus resonances are dispersed over 2 parts per million in the O6meG X A 12-mer and over 1 part per million in the O6meG X G 12-mer compared to a 0.5 part per million dispersion for an unperturbed DNA helix. We propose tentative pairing schemes for the A3 X O6meG10 and G3 X O6meG10 interactions in the above dodecanucleotide duplexes.     

Induction of male and female sterility in isabgol (<Emphasis Type="Italic">Plantago ovata</Emphasis>) due to floral infection of downy mildew (<Emphasis Type="Italic">Pernospora plantaginis</Emphasis>)

Downy mildew (Peronospora plantaginis) caused two different types of infection in the floral parts of isabgol (Plantago ovata). Systemic infection resulted in long spikes bearing weak and sterile florets, which later turned black due to saprophytic growth. Localised infection produced various symptoms ranging between normal flower opening and failure to bloom. Different parts of infected flowers such as sepal, petal, filament and anther were reduced in size compared to healthy flowers. However, gynoecium was elongated in localised infection. P. plantaginis induced gradual sterility of isabgol flowers. Androecium was affected more than the gynoecium was. Pollen number, pollen viability and germination reduced drastically due to localised infection. On the contrary, there were no significant differences between healthy and locally infected flowers in terms of stigma receptivity. In systemically infected spikes, bud development was arrested leading to sterility. When localised disease severity was high, secondary systemic infection caused similar symptoms. Microscopic observations showed presence of the pathogen in different parts of the flowers. Downy mildew adversely affected seed yield and quality; producing seeds, which were smaller and lighter than the healthy ones and later, became black. Seed yield was reduced by as much as 73.45 percent. Husk content per unit seed mass increased relatively as the total surface area of infected seeds increased.     

Truthful online double auction based dynamic resource provisioning for multi-objective trade-offs in IaaS clouds

Auction designs have recently been adopted for static and dynamic resource provisioning in IaaS clouds, such as Microsoft Azure and Amazon EC2. However, the existing mechanisms are mostly restricted to simple auctions, single-objective, offline setting, one-sided interactions either among cloud users or cloud service providers (CSPs), and possible misreports of cloud user’s private information. This paper proposes a more realistic scenario of online auctioning for IaaS clouds, with the unique characteristics of elasticity for time-varying arrival of cloud user requests under the time-based server maintenance in cloud data centers. We propose an online truthful double auction technique for balancing the multi-objective trade-offs between energy, revenue, and performance in IaaS clouds, consisting of a weighted bipartite matching based winning-bid determination algorithm for resource allocation and a Vickrey–Clarke–Groves (VCG) driven algorithm for payment calculation of winning bids. Through rigorous theoretical analysis and extensive trace-driven simulation studies exploiting Google cluster workload traces, we demonstrate that our mechanism significantly improves the performance while promising truthfulness, heterogeneity, economic efficiency, individual rationality, and has a polynomial-time computational complexity.

     

HECT Domain-containing E3 Ubiquitin Ligase Nedd4 Interacts with and Ubiquitinates Sprouty2

Sprouty (Spry) proteins are important regulators of receptor tyrosine kinase signaling in development and disease. Alterations in cellular Spry content have been associated with certain forms of cancers and also in cardiovascular diseases. Thus, understanding the mechanisms that regulate cellular Spry levels are important. Herein, we demonstrate that Spry1 and Spry2, but not Spry3 or Spry4, associate with the HECT domain family E3 ubiquitin ligase, Nedd4. The Spry2/Nedd4 association involves the WW domains of Nedd4 and requires phosphorylation of the Mnk2 kinase sites, Ser¹¹² and Ser¹²¹, on Spry2. The phospho-Ser^112/121 region on Spry2 that binds WW domains of Nedd4 is a novel non-canonical WW domain binding region that does not contain Pro residues after phospho-Ser. Endogenous and overexpressed Nedd4 polyubiquitinate Spry2 via Lys⁴⁸ on ubiquitin and decrease its stability. Silencing of endogenous Nedd4 increased the cellular Spry2 content and attenuated fibroblast growth factor-elicited ERK1/2 activation that was reversed when elevations in Spry2 levels were prevented by Spry2-specific small interfering RNA. Mnk2 silencing decreased Spry2-Nedd4 interactions and also augmented the ability of Spry2 to inhibit fibroblast growth factor signaling. This is the first report demonstrating the regulation of cellular Spry content and its ability to modulate receptor tyrosine kinase signaling by a HECT domain-containing E3 ubiquitin ligase.     

The impact of aging on innate and adaptive immunity in the human female genital tract

Mucosal tissues in the human female reproductive tract (FRT) are primary sites for both gynecological cancers and infections by a spectrum of sexually transmitted pathogens, including human immunodeficiency virus (HIV), that compromise women''s health. While the regulation of innate and adaptive immune protection in the FRT by hormonal cyclic changes across the menstrual cycle and pregnancy are being intensely studied, little to nothing is known about the alterations in mucosal immune protection that occur throughout the FRT as women age following menopause. The immune system in the FRT has two key functions: defense against pathogens and reproduction. After menopause, natural reproductive function ends, and therefore, two overlapping processes contribute to alterations in immune protection in aging women: menopause and immunosenescence. The goal of this review is to summarize the multiple immune changes that occur in the FRT with aging, including the impact on the function of epithelial cells, immune cells, and stromal fibroblasts. These studies indicate that major aspects of innate and adaptive immunity in the FRT are compromised in a site‐specific manner in the FRT as women age. Further, at some FRT sites, immunological compensation occurs. Overall, alterations in mucosal immune protection contribute to the increased risk of sexually transmitted infections (STI), urogenital infections, and gynecological cancers. Further studies are essential to provide a foundation for the development of novel therapeutic interventions to restore immune protection and reverse conditions that threaten women''s lives as they age.     

Potential of fruit and vegetable wastes as novel biosorbents: summarizing the recent studies

Fruit and vegetable wastes produced in astronomical quantities from food processing and agriculture industries often cause nuisance in municipal landfills owing to their high biodegradability. Biosorption by these waste-based adsorbents can be used as a cost effective and efficient technique for the removal of toxic heavy metals and dyes from wastewater. Recently, many papers claiming the feasible use of these biosorbents for water decontamination, treatment of industrial and agricultural wastewater and valuable metal recovery have been published. The organic waste-based adsorbents, characterized by good uptake capacity and rapid kinetics are expected to be economically and ecologically viable. This paper presents a judicious and pragmatic review depicting the key advances in implications of the fruit and vegetable wastes in pollution mitigation, the underlying mechanisms, major challenges and the future implementations. This compilation is expected to provide an impetus to the bioremediation research and promote green technology.     

Inferring subjective states through the observation of actions

Estimating another person''s subjective confidence is crucial for social interaction, but how this inference is achieved is unknown. Previous research has demonstrated that the speed at which people make decisions is correlated with their confidence in their decision. Here, we show that (i) subjects are able to infer the subjective confidence of another person simply through the observation of their actions and (ii) this inference is dependent upon the performance of each subject when executing the action. Crucially, the latter result supports a model in which motor simulation of an observed action mediates the successful understanding of other minds. We conclude that kinematic understanding allows access to the higher-order cognitive processes of others, and that this access plays a central role in social interactions.