Behavioral responses of the whitebacked planthopperSogatella furcifera (Homoptera: Delphacidae) on rice plants whose odors have been masked

In a two-choice test, moreS. furcifera females settled more often on exposed plants than on parafilm-masked ones, regardless of the susceptibility of rice varieties. This indicates that rice volatiles play an important role in the insect's short-range orientation to its host. The fact that more insects settled on exposed resistant Rathu Heenati (RHT) than to masked susceptible Taichung Native 1 (TN1) suggests that there must be certain common volatiles released by both varieties. Few females landed on masked plants of either RHT or TN1. This implies that the insect could not recognize at a distance that a plant was resistant or susceptible without olfactory stimuli.S. furcifera excreted less honeydew on masked plants than on exposed ones for both varieties and more on masked TN1 than on exposed RHT. The electronic monitoring of feeding behavior demonstrates that the insect made more frequent probes and had shorter phloem ingestion durations on exposed RHT than on exposed TN1 and on masked RHT than on masked TN1. Moreover, the insect had longer phloem ingestion durations on masked TN1 than on exposed RHT. These results suggest that volatile chemicals given off by resistant RHT plants have a negative effect on feeding.     

Microbial Oxidation of Hydrocarbons: Properties of a Soluble Methane Monooxygenase from a Facultative Methane-Utilizing Organism, Methylobacterium sp. Strain CRL-26

Methylobacterium sp. strain CRL-26 grown in a fermentor contained methane monooxygenase activity in soluble fractions. Soluble methane monooxygenase catalyzed the epoxidation/hydroxylation of a variety of hydrocarbons, including terminal alkenes, internal alkenes, substituted alkenes, branched-chain alkenes, alkanes (C₁ to C₈), substituted alkanes, branched-chain alkanes, carbon monoxide, ethers, and cyclic and aromatic compounds. The optimum pH and temperature for the epoxidation of propylene by soluble methane monooxygenase were found to be 7.0 and 40°C, respectively. Among various compounds tested, only NADH₂ or NADPH₂ could act as an electron donor. Formate and NAD⁺ (in the presence of formate dehydrogenase contained in the soluble fraction) or 2-butanol in the presence of NAD⁺ and secondary alcohol dehydrogenase generated the NADH₂ required for the methane monooxygenase. Epoxidation of propylene catalyzed by methane monooxygenase was not inhibited by a range of potential inhibitors, including metal-chelating compounds and potassium cyanide. Sulfhydryl agents and acriflavin inhibited monooxygenase activity. Soluble methane monooxygenase was resolved into three components by ion-exchange chromatography. All three compounds are required for the epoxidation and hydroxylation reactions.     

Light-dependent hypersensitive response and resistance signaling against Turnip Crinkle Virus in Arabidopsis

Resistance to Turnip Crinkle Virus (TCV) in Arabidopsis ecotype Dijon (Di)-17 is conferred by the resistance gene HRT and a recessive locus rrt. In Di-17, TCV elicits a hypersensitive response (HR), which is accompanied by increased expression of pathogenesis-related (PR) genes and high levels of salicylic acid (SA). We have previously shown that HRT-mediated resistance to TCV is dependent on SA-mediated signal transduction and that increased levels of SA confer enhanced resistance to TCV via upregulation of the HRT gene. Here we show that HRT-mediated HR and resistance are dependent on light. A dark treatment immediately following TCV inoculation suppressed HR, resistance and activation of the majority of the TCV-induced genes. However, the absence of light did not affect either TCV-induced elevated levels of free SA or the expression of HRT. Interestingly, in the dark, transgenic plants overexpressing HRT showed susceptibility, but overexpression of HRT coupled with high levels of endogenous SA resulted in pronounced resistance. Consistent with these results is the finding that exogenous application of SA prior to TCV inoculation partially overcame the requirement for light. Light was also required for N gene-mediated HR and resistance to Tobacco Mosaic Virus, suggesting that it is an important factor which may be generally required during defense signaling.     

Characterization of acid-induced molten globule like state of ficin

Effect of pH on the conformational behaviour of ficin (EC 3.4.22.3), a cysteine protease from the latex of Ficus carica was monitored by circular dichroism, fluorescence spectroscopy, ANS binding and hydrodynamic studies. The results obtained from near- and far-UV CD, intrinsic fluorescence and ANS binding studies demonstrate that ficin exhibits the characteristic properties of molten globule at acidic conditions between pH 1.4 and 2.0. Ficin at pH 1.4 retained about 74% secondary structure with a substantial loss of tertiary structure. The acid-induced state was found to have a compact shape as measured by Stokes radius on size exclusion chromatography.     

Slit protein-mediated inhibition of CXCR4-induced chemotactic and chemoinvasive signaling pathways in breast cancer cells

Slit, which mediates its function by binding to the Roundabout (Robo) receptor, has been shown to regulate neuronal and CXCR4-mediated leukocyte migration. Slit-2 was shown to be frequently inactivated in lung and breast cancers because of hypermethylation of its promoter region. Furthermore, the CXCR4/CXCL12 axis has been reported recently to be actively involved in breast cancer metastasis to target organs such as lymph nodes, lung, and bone. In this study, we sought to characterize the effect of Slit (=Slit-2) on the CXCL12/CXCR4-mediated metastatic properties of breast cancer cells. We demonstrate here that breast cancer cells and tissues derived from breast cancer patients express Robo 1 and 2 receptors. We also show that Slit treatment inhibits CXCL12/CXCR4-induced breast cancer cell chemotaxis, chemoinvasion, and adhesion, the fundamental components that promote metastasis. Slit had no significant effect on the CXCL12-induced internalization process of CXCR4. In addition, characterization of signaling events revealed that Slit inhibits CXCL12-induced tyrosine phosphorylation of focal adhesion components such as RAFTK/Pyk2 at residues 580 and 881, focal adhesion kinase at residue 576, and paxillin. We found that Slit also inhibits CXCL12-induced phosphatidylinositol 3-kinase, p44/42 MAP kinase, and metalloproteinase 2 and 9 activities. However, it showed no effect on JNK and p38 MAP kinase activities. To our knowledge, this is the first report to analyze in detail the effect of Slit on breast cancer cell motility as well as its effect on the critical components of the cancer cell chemotactic machinery. Studies of the Slit-Robo complex may foster new anti-chemotactic approaches to block cancer cell metastasis.     

Plant proteomics in India and Nepal: current status and challenges ahead

Plant proteomics has made tremendous contributions in understanding the complex processes of plant biology. Here, its current status in India and Nepal is discussed. Gel-based proteomics is predominantly utilized on crops and non-crops to analyze majorly abiotic (49 %) and biotic (18 %) stress, development (11 %) and post-translational modifications (7 %). Rice is the most explored system (36 %) with major focus on abiotic mainly dehydration (36 %) stress. In spite of expensive proteomics setup and scarcity of trained workforce, output in form of publications is encouraging. To boost plant proteomics in India and Nepal, researchers have discussed ground level issues among themselves and with the International Plant Proteomics Organization (INPPO) to act in priority on concerns like food security. Active collaboration may help in translating this knowledge to fruitful applications.     

Analysis of propagation of <Emphasis Type="Italic">Bacopa monnieri</Emphasis> (L.) from hairy roots,elicitation and Bacoside A contents of Ri transformed plants

Agrobacterium rhizogenes mediated transformation has been experimented in leaf explants of the memory herb Bacopa monnieri in order to assess the regeneration potential of hairy roots (HR) followed by the elicitation of transformed plants for increased Bacoside A production. Out of the four strains tested, A4 and MTCC 532 derived HR exhibited regrowth in MS basal medium while MTCC 2364 derived HR showed regeneration in MS medium supplemented with suitable phyto hormones. R1000 derived HR possessed no regeneration potential. Comparable to A4, MTCC 532 derived HR displayed maximum regrowth frequency of about 85.71 ± 1.84 % with an increase in biomass to threefold. Therefore, five HR plant lines (MTCC 532 derived) were generated and maintained in MS basal liquid medium in which HR3 topped the others in producing a huge biomass of about 67.09 ± 0.66 g FW. PCR amplification and southern hybridization analysis of rol A gene (280 bp) has been performed in order to confirm the transformation process. Moreover, HR3 plant line has accumulated highest total phenolic content of about 165.68 ± 0.82 mg GAE/g DW and highest total flavonoid content of about 497.78 ± 0.57 mg QRE/g DW when compared to other lines and untransformed controls. In addition, HR3 plant extract showed 85.58 ± 0.14 % of DPPH (2, 2-diphenyl-1-picryl hydrazyl) inhibition displaying its reliable anti oxidant potential. Further on elicitation with 10 mg/L chitosan for 2 weeks, HR3 has produced 5.83 % of Bacoside A which is fivefold and threefold increased production when compared to untransformed and transformed unelicited controls respectively. This is the first report on eliciting HR plants for increased metabolite accumulation in B. monnieri.     

Origin and radiation of the house mouse: clues from nuclear genes

Although quite a lot is known about the genetic structure of the polytypic species Mus musculus at the periphery of its range, the centre of origin and dispersion of the species remains unknown. To investigate the amount of genetic subdivision that occurs in the central parts of its range, we analysed the genetic variation in four new samples of mice coming from Iran, Pakistan, northern and southern India using 35 autosomal protein loci and restriction fragment length polymorphisms of three genes of the Vβ gene complex of the immune system. The variation was then compared with that found in the subspecies occupying the peripheral regions of the species range. The two samples from the northern part of the Indian subcontinent were shown to be more heterozygous than the samples from any of the other regions. They also contain the majority of the alleles that exist in the differentiated subspecies at the periphery of the species range. A neighbour-joining analysis on Nei's genetic distances and a factorial analysis of correspondences on the allelic composition of each sample both place the Pakistani and Indian populations in a phylogenetically and genetically central position compared to the peripheral subspecies. These results suggest that the populations in this geographically central area have retained most of the ancestral polymorphisms, which in turn indicates that the Indian subcontinent is probably the cradle of the species. The nature of the genetic relationships between the various populations throughout the species range and the possibility that they form an incipient ring species are also discussed. Our results are in agreement with the classical model of geographic differentiation where genetic divergence in allopatry is considered to be the prime cause of subspecies formation that may eventually lead to partial reproductive isolation on secondary contact.     

The role of protein kinases and protein phosphatases in the regulation of cardiac sarcoplasmic reticulum function

Summary Canine cardiac sarcoplasmic reticulum is phosphorylated by adenosine 3,5-monophosphate (cAMP)-dependent and by calcium · calmodulin-dependent protein kinases on a 27 000 proteolipid, called phospholamban. Both types of phosphorylation are associated with an increase in the initial rates of Ca²⁺ transport by SR vesicles which reflects an increased turnover of elementary steps of the calcium ATPase reaction sequence. The stimulatory effects of the protein kinases on the calcium pump may be reversed by an endogenous protein phosphatase, which can dephosphorylate both the CAMP-dependent and the calcium · calmodulin-dependent sites on phospholamban. Thus, the calcium pump in cardiac sarcoplasmic reticulum appears to be under reversible regulation mediated by protein kinases and protein phosphatases.