Interaction of microtubules with active principles of Xanthium strumarium

Indigenous variety of Xanthium strumarium (X. strumarium) was screened for its antimitotic activity using the microtubule-tubulin system isolated from mammalian tissue. A preliminary phytochemical screening of the whole extracts of the plant was carried out followed by partial purification of the whole extract of X.strumarium. The separated fractions obtained were identified and used for in vitro polymerization studies. The whole as well as partially separated chemical constituents of X. strumarium showed effective inhibition of tubulin polymerization. The results thus suggest that X. strumarium may possess antimitotic components.     

Evidence that helix 8 of rhodopsin acts as a membrane-dependent conformational switch

The crystal structure of rhodopsin revealed a cytoplasmic helical segment (H8) extending from transmembrane (TM) helix seven to a pair of vicinal palmitoylated cysteine residues. We studied the structure of model peptides corresponding to H8 under a variety of conditions using steady-state fluorescence, fluorescence anisotropy, and circular dichroism spectroscopy. We find that H8 acts as a membrane-surface recognition domain, which adopts a helical structure only in the presence of membranes or membrane mimetics. The secondary structural properties of H8 further depend on membrane lipid composition with phosphatidylserine inducing helical structure. Fluorescence quenching experiments using brominated acyl chain phospholipids and vesicle leakage assays suggest that H8 lies within the membrane interfacial region where amino acid side chains can interact with phospholipid headgroups. We conclude that H8 in rhodopsin, in addition to its role in binding the G protein transducin, acts as a membrane-dependent conformational switch domain.     

Differential effects of viewpoint on object-driven activation in dorsal and ventral streams

Using fMRI, we showed that an area in the ventral temporo-occipital cortex (area vTO), which is part of the human homolog of the ventral stream of visual processing, exhibited priming for both identical and depth-rotated images of objects. This pattern of activation in area vTO corresponded to performance in a behavioral matching task. An area in the caudal part of the intraparietal sulcus (area cIPS) also showed priming, but only with identical images of objects. This dorsal-stream area treated rotated images as new objects. The difference in the pattern of priming-related activation in the two areas may reflect the respective roles of the ventral and dorsal streams in object recognition and object-directed action.     

Transbilayer movement of dipalmitoylphosphatidylcholine in proteoliposomes reconstituted from detergent extracts of endoplasmic reticulum. Kinetics of transbilayer transport mediated by a single flippase and identification of protein fractions enriched in flippase activity

Phospholipid translocation (flip-flop) across membrane bilayers is typically assessed via assays utilizing partially water-soluble phospholipid analogs as transport reporters. These assays have been used in previous work to show that phospholipid translocation in biogenic (self-synthesizing) membranes such as the endoplasmic reticulum is facilitated by specific membrane proteins (flippases). To extend these studies to natural phospholipids while providing a framework to guide the purification of a flippase, we now describe an assay to measure the transbilayer translocation of dipalmitoylphosphatidylcholine, a membrane-embedded phospholipid, in proteoliposomes generated from detergent-solubilized rat liver endoplasmic reticulum. Translocation was assayed using phospholipase A(2) under conditions where the vesicles were determined to be intact. Phospholipase A(2) rapidly hydrolyzed phospholipids in the outer leaflet of liposomes and proteoliposomes with a half-time of approximately 0.1 min. However, for flippase-containing proteoliposomes, the initial rapid hydrolysis phase was followed by a slower phase reflecting flippase-mediated translocation of phospholipids from the inner to the outer leaflet. The amplitude of the slow phase was decreased in trypsin-treated proteoliposomes. The kinetic characteristics of the slow phase were used to assess the rate of transbilayer equilibration of phospholipids. For 250-nm diameter vesicles containing a single flippase, the half-time was 3.3 min. Proportionate reductions in equilibration half-time were observed for preparations with a higher average number of flippases/vesicle. Preliminary purification steps indicated that flippase activity could be enriched approximately 15-fold by sequential adsorption of the detergent extract onto anion and cation exchange resins.     

Computational and experimental analysis reveals a novel Src family kinase in the C. elegans genome

MOTIVATION: The complete genomes of a number of organisms have already been sequenced. However, the vast majority of annotated genes are derived by gene prediction methods. It is important to not only validate the predicted coding regions but also to identify genes that may have been missed by these programs. METHODS: We searched the entire C.elegans genomic sequence database maintained by the Sanger Center using human c-Src sequence in a TBLASN search. We have confirmed one of the predicted regions by isolation of a cDNA and carried out a phylogenetic analysis of Src kinase family members in the worm, fly and several vertebrate species. RESULTS: Our analysis identified a novel tyrosine kinase in the C.elegans genome that contains functional features typical of the Src family kinases that we have designated as Src-1. The open reading frame contains a conserved N-terminal myristoylation site and a tyrosine residue within the C-terminus that is crucial for regulating the activity of Src kinases. Our phylogenetic analysis of Src family members from C. elegans, Drosophila and other higher organisms revealed a relationship among Src kinases from C. elegans and Drosophila.     

Micropropagation and ecorestoration of Vanda spathulata,an exquisite orchid

Node explants collected from flowering plants of Vanda spathulata, an endemic and exquisite orchid of Peninsular India and Sri Lanka, were cultured in Mitra medium with combinations of 4.4–88.8 m 6-benzyl adenine (BA) and 0.0–114.2 m indole-3-acetic acid (IAA). Combinations of 44.4 m BA with 17.1 or 28.5 m IAA and 66.6 mM BA with 28.5 or 40.0 m IAA induced maximum formation of 12.6 and 12.1 shoots / node, respectively, in a 6-month period. Subcultured nodal explants produced maximum of 6.1 shoots at combinations of 22.2–44.4 m 21 BA and 5.7–28.5 m IAA. Rooting of shoots occurred in medium containing 75 g l^–1 banana pulp and 5.7 m IAA within 3–9 weeks. Plantlets of 2–5 cm length possessing two to five roots established easily in community pots at 80–90% rates without hardening. Community potted plants introduced into forest segments at Ponmudi and Palode in Southern Western Ghats of India established at a rate of 50–70%.     

From biological databases to platforms for biomedical discovery

The use of high-throughput DNA sequencing and proteomic methods has led to an unprecedented increase in the amount of genomic and proteomic data. Application of computing technologies and development of computational tools to analyze and present these data has not kept pace with the accumulation of information. Here, we discuss the use of different database systems to store biological information and mention some of the key emerging computing technologies that are likely to have a key role in the future of bioinformatics.     

Humor modulates the mesolimbic reward centers

Humor plays an essential role in many facets of human life including psychological, social, and somatic functioning. Recently, neuroimaging has been applied to this critical human attribute, shedding light on the affective, cognitive, and motor networks involved in humor processing. To date, however, researchers have failed to demonstrate the subcortical correlates of the most fundamental feature of humor-reward. In an effort to elucidate the neurobiological substrate that subserves the reward components of humor, we undertook a high-field (3 Tesla) event-related functional MRI study. Here we demonstrate that humor modulates activity in several cortical regions, and we present new evidence that humor engages a network of subcortical regions including the nucleus accumbens, a key component of the mesolimbic dopaminergic reward system. Further, the degree of humor intensity was positively correlated with BOLD signal intensity in these regions. Together, these findings offer new insight into the neural basis of salutary aspects of humor.     

Changes in the prostaglandin levels in alcohol toxicity: effect of curcumin and N-acetylcysteine

The present study was undertaken to evaluate the potential role of curcumin, the antioxidant principal from Curcuma longa Linn., and the sulphur-containing amino acid N-acetylcysteine against ethanol-induced changes in the levels of prostanoids. Biochemical assessment of liver damage was done by measuring the activities of serum enzymes (i.e., aspartate transaminase and alkaline phosphatase), which were significantly increased in rats fed ethanol, whereas the elevated levels of these enzymes were decreased after curcumin and N-acetylcysteine treatment to rats fed ethanol. We observed a significant increase in the levels of prostaglandins E(1), E(2), F(2alpha), and D(2) in liver, kidney, and brain. Administration of curcumin and N-acetylcysteine was shown to decrease the level of these prostanoids in the tissue studied.