Life histories ofPsyllaephagus yaseeni (Hym., Encyrtidae) andTamarixia leucaenae (Hym., Eulophidae), parasitoids of the leucaena psyllidHeteropsylla cubana

Age specific fecundity of two parasitoids,P. yaseeni andT. leucaenae, of the leucaena psyllidH. cubana, were studied under laboratory conditions. At 25 °C,P. yaseeni had a greater fecundity (R₀=192.9)_thanT. leucaenae (R₀=71.2);T. leucaenae however had a lower sex ratio (about 99 % females) thanP. yaseeni (about 50 % females). Innate capacity for increase (r_m=0.236) ofT. leucaenae was higher thanP. yaseeni (r_m=0.188). Developmental rates of the parasitoids were examined at constant and fluctuating temperatures and equations of the rate of development against temperature were calculated. At 25 °C, mean generation times were 28.0 and 18.1 days forP. yaeseeni andT. leucaenae respectively. At temperatures of 21.5, 25, and 30 °C total development times (egg to adult) were 28.5, 21.9, and 14.7 days inP. yaseeni and 19.2, 12.6, and 9.5 days inT. leucaenae respectively. The level of parasitism was low and pupal mortality was high at the lower temperature of 21.5 °C for both parasitoids. Both parasitoids showed poor survivorship at 100 % RH,P. yaseeni survived particularly well (32 days) at a temperature of 21.5 °C and 44 or 76 % RH. P. yaseeni allocated about 58 % females to first instar psyllid nymphs but only 12 % females to second instars. About 99 % of allT. leucaenae births were females. Significantly largerT. leucaenae females emerged from fifth instar parasitized nymphs than third or fourth instars.     

Isolation of succinate dehydrogenase from Desulfobulbus elongatus, a propionate oxidizing, sulfate reducing bacterium

Succinate dehydrogenase was purified from the particulate fraction of Desulfobulbus. The enzyme catalyzed both fumarate reduction and succinate oxidation but the rate of fumarate reduction was 8-times less than that of succinate oxidation. Quantitative analysis showed the presence of 1 mol of covalently bound flavin and 1 mol of cytochrome b per mol of succinate dehydrogenase. The enzyme contained three subunits with molecular mass 68.5, 27.5 and 22 kDa. EPR spectroscopy indicated the presence of at least two iron sulfur clusters. 2-Heptyl-4-hydroxy-quinoline-N-oxide inhibited the electron-transfer between succinate dehydrogenase and a high redox potential cytochrome c3 from Desulfobulbus elongatus.     

Suppression of bacterial cell–cell signalling,biofilm formation and type III secretion system by citrus flavonoids

Aim: This study investigated the quorum sensing, biofilm and type three secretion system (TTSS) inhibitory properties of citrus flavonoids. Methods and Results: Flavonoids were tested for their ability to inhibit quorum sensing using Vibrio harveyi reporter assay. Biofilm assays were carried out in 96‐well plates. Inhibition of biofilm formation in Escherichia coli O157:H7 and V. harveyi by citrus flavonoids was measured. Furthermore, effect of naringenin on expression of V. harveyi TTSS was investigated by semi‐quantitative PCR. Differential responses for different flavonoids were observed for different cell–cell signalling systems. Among the tested flavonoids, naringenin, kaempferol, quercetin and apigenin were effective antagonists of cell–cell signalling. Furthermore, these flavonoids suppressed the biofilm formation in V. harveyi and E. coli O157:H7. In addition, naringenin altered the expression of genes encoding TTSS in V. harveyi. Conclusion: The results of the study indicate a potential modulation of bacterial cell–cell communication, E. coli O157:H7 biofilm and V. harveyi virulence, by flavonoids especially naringenin, quercetin, sinensetin and apigenin. Among the tested flavonoids, naringenin emerged as potent and possibly a nonspecific inhibitor of autoinducer‐mediated cell–cell signalling. Naringenin and other flavonoids are prominent secondary metabolites present in citrus species. Therefore, citrus, being a major source of some of these flavonoids and by virtue of widely consumed fruit, may modulate the intestinal microflora. Significance and Impact of the Study: Currently, a limited number of naturally occurring compounds have demonstrated their potential in inhibition of cell–cell communications; therefore, citrus flavonoids may be useful as lead compounds for the development of antipathogenic agents.     

Ubiquitous presence of normally non-culturable endophytic bacteria in field shoot-tips of banana and their gradual activation to quiescent cultivable form in tissue cultures

Exploring the source of quiescent bacteria in tissue-cultured bananas (Musa sp.) we demonstrate here through a combination of bacterial 16S rDNA-based molecular technique, light microscopy and cultivation-based approaches the ubiquitous presence of endophytic bacteria in the field shoots of different genotypes (Grand Naine, Robusta, Dwarf Cavendish, Ney Poovan and exotic accessions) and their widespread prevalence in apparently clean tissue cultures. A portion of field shoot-tips (10–60%) showed cultivable endophytes, especially during rainy season, yielding 10²–10⁵ colony forming units g⁻¹ fresh tissue in ‘Grand Naine’, which overtly expressed on tissue culture medium as well. The rest showed no colony development on diverse bacteriological media but proved PCR^+ve to bacterial primers indicating the presence of normally non-culturable organisms, which was endorsed by microscopic observations. Such endophytes gradually turned cultivable rendering all visibly clean cultures as quiescent bacteria-harboring after a few (2–4) to several (8–20) passages, resulting in as much as 1.7 × 10⁵ – 4.0 × 10⁷ colony forming units g⁻¹ tissue of ‘Grand Naine’ after ten passages, yielding different organisms. This study has thus exposed the ubiquitous and intense association existing between endophytes and bananas, including their quiescent survival in suspension cultures. The effect due to quiescent bacteria in micropropagated stocks could not be generalized. The observations question the fundamental principle of asepsis in plant tissue cultures and bring in new information on plant-endophtye association in vitro with implications in micropropagation, germplasm conservation, cell culture studies and molecular profiling. The possible involvement of unsuspected endophytic bacteria in tissue-culture associated phenomena like habituation and epigenetic and somaclonal variations are discussed.     

Collagen Promotes Higher Adhesion,Survival and Proliferation of Mesenchymal Stem Cells

Mesenchymal stem cells (MSC) can differentiate into several cell types and are desirable candidates for cell therapy and tissue engineering. However, due to poor cell survival, proliferation and differentiation in the patient, the therapy outcomes have not been satisfactory. Although several studies have been done to understand the conditions that promote proliferation, differentiation and migration of MSC in vitro and in vivo, still there is no clear understanding on the effect of non-cellular bio molecules. Of the many factors that influence the cell behavior, the immediate cell microenvironment plays a major role. In this context, we studied the effect of extracellular matrix (ECM) proteins in controlling cell survival, proliferation, migration and directed MSC differentiation. We found that collagen promoted cell proliferation, cell survival under stress and promoted high cell adhesion to the cell culture surface. Increased osteogenic differentiation accompanied by high active RHOA (Ras homology gene family member A) levels was exhibited by MSC cultured on collagen. In conclusion, our study shows that collagen will be a suitable matrix for large scale production of MSC with high survival rate and to obtain high osteogenic differentiation for therapy.     

Effect of nimesulide on acetic acid- and leukotriene-induced inflammatory bowel disease in rats

Inflammatory bowel disease (IBD) is a relapsing inflammation of intestine, which is mediated by release of inflammatory mediators. Both cyclo-oxygenase product prostaglandin (PGE2) and lipo-oxygenase product leukotriene (LTB4), may contribute to the pathogenesis of the inflammatory response. Nimesulide, a preferential COX-2 inhibitor was evaluated for its efficacy against experimental colitis in two different models (acetic acid- and LTB4-induced IBD) in rats. Inflammatory response was induced by intrarectal single administration of acetic acid or LTB4. Nimesulide (9 and 18 mg/kg, p.o.) significantly prevented development of inflammatory changes, decreased myeloperoxidase (MPO) activity, and also restored the altered contractility response of the isolated colon segment to KCl. The results suggested the involvement of both cyclo-oxygenase (COX) and lipo-oxygenase-mediated proinflammatory agents in colonic inflammatory process associated with IBD. Further, this study suggests that such therapeutic interventions may be of value in the treatment of IBD.     

Synthesis and Conformational Studies of O 5′, 6-Methanouridine—A New Type of Pyrimidine Cyclonucleoside

Abstract

The 5-oxo-6-methylene-pyrimidine-2,4-dione intermediate (6) that is formed when 5-acetoxy-6-acetoxymethyl-1-β-D-(5-O-acetyl-2,3-O-isopropylidene)-ribofuranosyluracil (5) is treated with sodium hydroxide undergoes cyclization at pH 14 to give 2′,3′-O-isopropylidene-5-hydroxy- O ⁵, 6-methanouridine (8) in good yield. Conversion of 8 into the 5-triflate ester 14 followed by reduction with [(Ph)₃P]₄Pd/Bu₃SnH and deblocking with acetic acid then affords O ^5′, 6-methanouridine (4) Conformational studies (NOE difference spectra, vicinal ¹H-¹³C coupling constants, NOESY and CD spectra, molecular modeling) indicate that the C7-methylene group of 4 projects towards the furanose ring oxygen atom, producing a glycosyl rotation angle of about ? 160°.     

Mesothelin Expression in Triple Negative Breast Carcinomas Correlates Significantly with Basal-Like Phenotype,Distant Metastases and Decreased Survival

Mesothelin is a cell surface associated antigen expressed on mesothelial cells and in some malignant neoplasms. Mesothelin-targeted therapies are in phase I/II clinical trials. The clinicopathologic and prognostic significance of mesothelin expression in triple negative breast carcinomas (TNBC) has not been fully assessed. We evaluated the expression of mesothelin and of basal markers in tissue microarrays of 226 TNBC and 88 non-TNBC and assessed the clinicopathologic features of mesothelin-expressing breast carcinomas. Furthermore, we investigated the impact of mesothelin expression on the disease-free and overall survival of patients with TNBC. We found that mesothelin expression is significantly more frequent in TNBC than in non-TNBC (36% vs 16%, respectively; p = 0.0006), and is significantly correlated with immunoreactivity for basal keratins, but not for EGFR. Mesothelin-positive and mesothelin-negative TNBC were not significantly different by patients’ race, tumor size, histologic grade, tumor subtype, lymphovascular invasion and lymph node metastases. Patients with mesothelin-positive TNBC were older than patients with mesothelin-negative TNBC, developed more distant metastases with a shorter interval, and had significantly lower overall and disease-free survival. Based on our results, patients with mesothelin-positive TNBC could benefit from mesothelin-targeted therapies.     

UV-B induced transcript accumulation of DAHP synthase in suspension-cultured Catharanthus roseus cells

Background

AMP-activated protein kinase (AMPK) is a fuel-sensing enzyme that is activated when cells experience energy deficiency and conversely suppressed in surfeit of energy supply. AMPK activation improves insulin sensitivity via multiple mechanisms, among which AMPK suppresses mTOR/S6K-mediated negative feedback regulation of insulin signaling.

Results

In the present study we further investigated the mechanism of AMPK-regulated insulin signaling. Our results showed that 5-aminoimidazole-4-carboxamide-1 ribonucleoside (AICAR) greatly enhanced the ability of insulin to stimulate the insulin receptor substrate-1 (IRS1)-associated PI3K activity in differentiated 3T3-F442a adipocytes, leading to increased Akt phosphorylation at S473, whereas insulin-stimulated activation of mTOR was diminished. In 3T3-F442a preadipocytes, these effects were attenuated by expression of a dominant negative mutant of AMPK α1 subunit. The enhancing effect of ACIAR on Akt phosphorylation was also observed when the cells were treated with EGF, suggesting that it is regulated at a step beyond IR/IRS1. Indeed, when the cells were chronically treated with AICAR in the absence of insulin, Akt phosphorylation was progressively increased. This event was associated with an increase in levels of phosphatidylinositol -3,4,5-trisphosphate (PIP3) and blocked by Wortmannin. We then expressed the dominant negative mutant of PTEN (C124S) and found that the inhibition of endogenous PTEN per se did not affect phosphorylation of Akt at basal levels or upon treatment with AICAR or insulin. Thus, this result suggests that AMPK activation of Akt is not mediated by regulating phosphatase and tensin homologue (PTEN).

Conclusion

Our present study demonstrates that AMPK exerts dual effects on the PI3K pathway, stimulating PI3K/Akt and inhibiting mTOR/S6K.