Induction of preference and performance after acclimation to novel hosts in a phytophagous spider mite: adaptive plasticity?

We examined induction of preference and performance on novel host plants for two laboratory populations of the polyphagous spider mite Tetranychus urticae, with one population adapted to bean and the other population adapted to tomato. We bred four isofemale lines of the bean population only and used them in all the assays. The bean population had a 30% lower fecundity on tomato than on bean, while the tomato population had equal fecundity on both host plants. Acclimation of adult females to the novel host plant for both populations increased acceptability of that novel host but did not increase rejection of the original host. The bean population experienced a 60% benefit and a 30% cost in terms of egg production for acclimating to tomato, thus exemplifying adaptive plasticity. The tomato population showed a 23% benefit for acclimating to bean but no cost. Mites from the bean population that were acclimated to tomato fed more on tomato than did mites that were not acclimated to tomato. When these mites were fed inhibitors of cytochrome P-450 detoxification enzymes, their performance was severely depressed (84%) on tomato but not on bean. However, mites that were fed inhibitors of P-450 enzymes did not reduce their acceptance of tomato as a host. Thus, performance on novel hosts (but not preference) in this species is likely correlated with the induction of detoxifying enzymes. Spider mites are known to form host races rapidly on novel hosts. Induction of preference and physiological acclimation via detoxification enzymes may enhance performance and, thus, strongly contribute to initial stages of host race formation.     

Proteome analysis of differentially displayed proteins as a tool for investigating ozone stress in rice (Oryza sativa L.) seedlings

Employing classical two-dimensional electrophoresis (2-DE), amino acid sequencing and immunoblot analysis, we examine for the first time the effect of ozone, a highly notorious environmental pollutant, on rice seedling proteins. Drastic visible necrotic damage to leaf by ozone and consequent increase in ascorbate peroxidase protein(s) was accompanied by rapid changes in the 2-DE protein profiles, over controls. Out of a total of 56 proteins investigated, which were reproducible in repeated experiments, 52 protein spots were visually identified as differentially expressed over controls. Six proteins were N-terminally blocked, and the sequence of 14 proteins could not be determined, whereas 36 proteins were N-terminally and one was internally sequenced. Ozone caused drastic reductions in the major leaf photosynthetic proteins, including the abundantly present ribulose-1, 5-bisphosphate carboxylase/oxygenase, and induction of various defense/stress related proteins. Most prominent change in leaves, within 24 h post-treatment with ozone, was the induced accumulation of a pathogenesis related (PR) class 5 protein, three PR 10 class proteins, ascorbate peroxidase(s), superoxide dismutase, calcium-binding protein, calreticulin, a novel ATP-dependent CLP protease, and an unknown protein. Present results demonstrate the highly damaging effect of ozone on rice seedlings at the level of the proteome.     

On the topological evidences for modelling lipophilicity

Topological evidences for modelling lipophilicity of a large series of diversed compounds have been provided on the basis of distance-based topological indices. A pool of topological indices along with indicator parameters related to the type of the compounds present in the set of 140 compounds were used for this purpose. The results have shown that topology as well as the type of compounds are the responsible parameters for modelling lipophilicity.     

Immunostimulatory properties of phosphorothioate CpG DNA containing both 3'-5'- and 2'-5'-internucleotide linkages

Synthetic oligodeoxyribonucleotides containing CpG-dinucleotides (CpG DNA) in specific sequence contexts activate the vertebrate immune system. We have examined the effect of 3′-deoxy-2′–5′-ribonucleoside (3′-deoxynucleoside) incorporation into CpG DNA on the immunostimulatory activity. Incorporation of 3′-deoxynucleosides results in the formation of 2′–5′-internucleotide linkages in an otherwise 3′–5′-linked CpG DNA. In studies, both in vitro and in vivo, CpG DNA containing unnatural 3′-deoxynucleoside either within the CpG-dinucleotide or adjacent to the CpG-dinucleotide failed to induce immunostimulatory activity, suggesting that the modification was not recognized by the receptors. Incorporation of the same modification distal to the CpG-dinucleotide in the 5′-flanking sequence potentiated the immunostimulatory activity of the CpG DNA. The same modification when incorporated in the 3′-flanking sequence had an insignificant effect on immunostimulatory activity of CpG DNA. Interestingly, substitution of a 3′-deoxynucleoside in the 5′-flanking sequence distal to the CpG-dinucleotide resulted in increased IL-6 and IL-10 secretion with similar levels of IL-12 compared with parent CpG DNA. The incorporation of the same modification in the 3′-flanking sequence resulted in lower IL-6 and IL-10 secretion with similar levels of IL-12 compared with parent CpG DNA. These results suggest that site-specific incorporation of 3′-deoxynucleotides in CpG DNA modulates immunostimulatory properties.     

Octadecanoid signaling component "burst" in rice (Oryza sativa L.) seedling leaves upon wounding by cut and treatment with fungal elicitor chitosan

Octadecanoid pathway components, 12-oxo-phytodieonic acid (OPDA) and jasmonic acid (JA), are key biologically active regulators of plant self-defense response(s). However, to date these compounds have been studied mostly in dicots, and used large (1-10 g fresh weight, FW) samples for quantification, even when examined in mature rice plants, which is a drawback considering their rapid responsiveness to stress. Focusing on rice--a monocot cereal crop research model--this work describes an efficient and simultaneous quantification of both OPDA and JA using a minimum amount of 200mg FW seedling leaf tissue upon wounding (by cut) and treatment with fungal elicitor, chitosan (CT) by high-pressure liquid chromatography-turboionspray tandem mass spectrometry. Transient OPDA/JA "burst" was consistently and reproducibly detected within 3 min in wounded and CT treated leaves. OPDA peaked dramatically around 5 min and returned to its basal level within 15 min, whereas JA induction upon wounding and CT treatment were in parallel to OPDA production, peaking at 30 and 60 min, respectively. Present results mark a major advance in our understanding of key inducible octadecanoid pathway components in rice, and strongly suggest a role for the octadecanoid pathway downstream of perception of at least these two fundamentally different extracellular stimuli.     

Potent CpG oligonucleotides containing phosphodiester linkages: in vitro and in vivo immunostimulatory properties

Bacterial and synthetic DNAs, containing CpG dinucleotides in specific sequence contexts, activate the vertebrate immune system. Unlike phosphorothioate (PS) CpG DNAs, phosphodiester (PO) CpG DNAs require either palindromic sequences and/or poly(dG) sequences at the 3(')-end for activity. Here, we report 'PO-immunomers' having two PO-CpG DNA molecules joined through their 3(')-ends. These PO-imunomers permitted us, for the first time, to assess immunostimulatory properties of PO-CpG DNAs in vitro and in vivo without the need for palindromic and/or poly(dG) sequences. In medium containing 10% fetal bovine serum, PO-immunomers were more resistant than PO-CpG DNAs to nucleases. Compared to PS-CpG DNA in BALB/c and C3H/HeJ mice spleen cell culture assays, PO-immunomers showed increased IL-12 secretion and minimal amounts of IL-6 secretion. PO-immunomers activated NF-kappa B and induced cytokine secretion in J774 cell cultures. In addition, PO-immunomers showed antitumor activity in nude mice bearing human breast (MCF-7) and prostate (DU145) cancer xenografts.     

Effective Protocol for in Vitro Shoot Production Through Nodal Explants of Simmondsia Chinensis

Nodal explants excised from 18 to 20-year-old female plants of Simmondsia chinensis if cultured on Murashige and Skoog's medium supplemented with 20 M N⁶-benzyladenine (BA) differentiated an average of 2.7 ± 0.4 shoots in 11.5% explants. The percentage of nodal explants inducing multiple shoots enhanced significantly if in vitro raised shoots were used as source of explants. Nearly 100% cultures differentiated an average of 4.7 ± 2.0 shoots per explant on the same medium. Nearly 85% of the shoots induced roots when a pulse treatment of 50 M indole-3-butyric acid (IBA) was given prior to their transfer to semi-solid MS medium containing 10 M IBA + 0.5% activated charcoal + 1 M BA. Plantlets were gradually hardened in Soilrite and acclimatized to soil.