Molecular genetics of cell death in the nematode Caenorhabditis elegans

In C. elegans, cell death can be readily studied at the cellular, genetic, and molecular levels. Two types of death have been characterized in this nematode: (1) programmed cell death, which occurs as a normal component in development; and (2) pathological cell death which occurs aberrantly as a consequence of mutation. Analysis of mutations that disrupt programmed cell death in various ways has defined a genetic pathway for programmed cell death which includes genes that perform such functions as the determination of which cells die, the execution of cell death, the engulfment of cell corpses, and the digestion of DNA from dead cells. Molecular analysis is providing insightinto the nature of the molecules that function in these aspects of programmed cell death. Characterization of some genes that mutate to induce abnormal cell death has defined a novel gene family called degenerins that encode putative membrane proteins. Dominant alleles of at least two degenerin genes, mec-4 and deg-1, can cause cellular swelling and late onset neurodegeneration of specific groups of cells. © 1992 John Wiley & Sons, Inc.     

Dimer–monomer equilibrium of human thymidylate synthase monitored by fluorescence resonance energy transfer

An ad hoc bioconjugation/fluorescence resonance energy transfer (FRET) assay has been designed to spectroscopically monitor the quaternary state of human thymidylate synthase dimeric protein. The approach enables the chemoselective engineering of allosteric residues while preserving the native protein functions through reversible masking of residues within the catalytic site, and is therefore suitable for activity/oligomerization dual assay screenings. It is applied to tag the two subunits of human thymidylate synthase at cysteines 43 and 43′ with an excitation energy donor/acceptor pair. The dimer–monomer equilibrium of the enzyme is then characterized through steady‐state fluorescence determination of the intersubunit resonance energy transfer efficiency.     

Effects of NaCl and iso-osmotic PEG stress on growth,osmolytes accumulation and antioxidant defense in cultured sugarcane cells

In order to discriminate between the ionic and osmotic components of salt stress, sugarcane (Saccharum officinarum L. cv. Co 86032) calli were cultured on media containing NaCl or polyethylene glycol (PEG) 8000 that exerted the same osmotic pressure (−0.7 MPa). PEG stress exposure for 15 days led to significant growth reduction and loss in water content than salt stressed and control tissues. Osmotic adjustment (OA) was observed in callus tissues grown on salt, but was not evident in callus grown on PEG. Oxidative damage to membranes, estimated in terms of accumulation of thiobarbituric acid reactive substances-TBARS and electrolytic leakage was significantly higher in both the stressed calli than the control however, the extent of damage was more in the PEG stressed calli. The stressed callus tissues showed inhibition of ascorbate peroxidase activity, while catalase activity was increased. These results indicate sensitivity of cells to PEG-mediated stress than salt stress and differences in their OA to these two stress conditions. The sensitivity to the osmotic stress indicate that expression of the stress tolerance response requires the coordinated action of different tissues in a plant and hence was not expressed at the cellular level.     

Collagen targeting using multivalent protein-functionalized dendrimers

Collagen is an attractive marker for tissue remodeling in a variety of common disease processes. Here we report the preparation of protein dendrimers as multivalent collagen targeting ligands by native chemical ligation of the collagen binding protein CNA35 to cysteine-functionalized dendritic divalent (AB₂) and tetravalent (AB₄) wedges. The binding of these multivalent protein constructs was studied on collagen-immobilized chip surfaces as well as to native collagen in rat intestinal tissues. To understand the importance of target density we also created collagen-mimicking surfaces by immobilizing synthetic collagen triple helical peptides at various densities on a chip surface. Multivalent display of a weak-binding variant (CNA35-Y175K) resulted in a large increase in collagen affinity, effectively restoring the collagen imaging capacities for the AB₄ system. In addition, dissociation of these multivalent CNA35 dendrimers from collagen surfaces was found to be strongly attenuated.     

Probing binding mechanism of interleukin-6 and olokizumab: in silico design of potential lead antibodies for autoimmune and inflammatory diseases

Computer-aided antibody engineering has been successful in the design of new biologics for disease diagnosis and therapeutic interventions. Interleukin-6 (IL-6), a well-recognized drug target for various autoimmune and inflammatory diseases such as rheumatoid arthritis, multiple sclerosis, and psoriasis, was investigated in silico to design potential lead antibodies. Here, crystal structure of IL-6 along with monoclonal antibody olokizumab was explored to predict antigen–antibody (Ag???Ab)-interacting residues using DiscoTope, Paratome, and PyMOL. Tyr56, Tyr103 in heavy chain and Gly30, Ile31 in light chain of olokizumab were mutated with residues Ser, Thr, Tyr, Trp, and Phe. A set of 899 mutant macromolecules were designed, and binding affinity of these macromolecules to IL-6 was evaluated through Ag???Ab docking (ZDOCK, ClusPro, and Rosetta server), binding free-energy calculations using Molecular Mechanics/Poisson Boltzman Surface Area (MM/PBSA) method, and interaction energy estimation. In comparison to olokizumab, eight newly designed theoretical antibodies demonstrated better result in all assessments. Therefore, these newly designed macromolecules were proposed as potential lead antibodies to serve as a therapeutics option for IL-6-mediated diseases.     

Linked Cross Sectional Schemes for Estimating Growth of Children

For estimation of growth, the efficiency of linked cross sectional scheme has been compared with pure longitudinal and cross sectional schemes. The relevant estimation theory has been developed and the expressions for the optimum estimators alongwith their variances have been derived. It has been observed that for estimation of growth, the linked cross-sectional scheme has been observed to be less efficient as compared to pure longitudinal scheme but more efficient than pure cross-sectional scheme.     

Tree ring imprints of long-term changes in climate in western Himalaya,India

Tree-ring analyses from semi-arid to arid regions in western Himalaya show immense potential for developing millennia long climate records. Millennium and longer ring-width chronologies of Himalayan pencil juniper (Juniperus polycarpos), Himalayan pencil cedar (Cedrus deodara) and Chilgoza pine (Pinus gerardiana) have been developed from different sites in western Himalaya. Studies conducted so far on various conifer species indicate strong precipitation signatures in ring-width measurement series. The paucity of weather records from stations close to tree-ring sampling sites poses difficulty in calibrating tree-ring data against climate data especially precipitation for its strong spatial variability in mountain regions. However, for the existence of strong coherence in temperature, even in data from distant stations, more robust temperature reconstructions representing regional and hemispheric signatures have been developed. Tree-ring records from the region indicate multi-century warm and cool anomalies consistent with the Medieval Warm Period and Little Ice Age anomalies. Significant relationships noted between mean premonsoon temperature over the western Himalaya and ENSO features endorse utility of climate records from western Himalayan region in understanding long-term climate variability and attribution of anthropogenic impact.     

Cluster analysis of behavioural and event-related potentials during a contingent negative variation paradigm in remitting-relapsing and benign forms of multiple sclerosis

Background  

Event-related potentials (ERPs) may be used as a highly sensitive way of detecting subtle degrees of cognitive dysfunction. On the other hand, impairment of cognitive skills is increasingly recognised as a hallmark of patients suffering from multiple sclerosis (MS). We sought to determine the psychophysiological pattern of information processing among MS patients with the relapsing-remitting form of the disease and low physical disability considered as two subtypes: 'typical relapsing-remitting' (RRMS) and 'benign MS' (BMS). Furthermore, we subjected our data to a cluster analysis to determine whether MS patients and healthy controls could be differentiated in terms of their psychophysiological profile.