Enhanced resistance to two stem borers in an aromatic rice containing a synthetic cryIA(b) gene

Rice cultivars of isozyme group V include high-quality, aromatic rices that are difficult to improve by traditional methods because of the loss of quality characters upon sexual hybridization. Their low-tillering plant type predisposes them to economic loss from attack by stem borers, a group of insects to which they are susceptible. We report here the enhancement of stem borer resistance in cv. Tarom Molaii through transformation by microprojectile bombardment. Embryogenic calli derived from mature seeds were bombarded with gold particles coated with plasmid pCIB4421, carrying a synthetic truncated toxin gene based on the cryIA(b) gene from Bacillus thuringiensis, and plasmid pHygII, carrying the hygromycin phosphotransferase (hpt) selectable marker gene. Inclusion of 50 mg/l hygromycin B in culture media from bombardment through to rooting of plantlets eliminated escapes. The procedure generated three independent hpt transformants of which two also contained the cryIA(b) gene. One such line (No. 827) produced truncated (67 kDa) CryIA(b) protein equivalent to about 0.1% of total soluble protein. The cryIA(b) gene was controlled by the promoter of the maize C₄ PEP carboxylase gene and was expressed in leaf blades but was not expressed to a detectable level in dehulled mature grain. Line 827 contained about 3 copies of the cryIA(b) gene which segregated as a single dominant Mendelian locus in the second (T₁) and third (T₂) generations and co-segregated with enhanced resistance to first-instar larvae of striped stem borer (Chilo suppressalis) and yellow stem borer (Scirpophaga incertulas). T₂ line 827-6 homozygous for the cryIA(b) gene showed no dead hearts or whiteheads after infestation with stem borers, whereas T₂ line 827-25 lacking the gene averaged 7 dead hearts per plant and 2.25 whiteheads per plant. These results establish that transformation of high-quality rices of group V is a feasible alternative to sexual hybridization.     

Effect of passive myocardium on the compliance of porcine coronary arteries

The objective of this study was to determine the effect of passive myocardium on the coronary arteries under distension and compression. To simulate distension and compression, we placed a diastolic-arrested heart in a Lucite box, where both the intravascular pressure and external (box) pressure were varied independently and expressed as a pressure difference (DeltaP = intravascular pressure - box pressure). The DeltaP-cross-sectional area relationship of the first several generations of porcine coronary arteries and the DeltaP-volume relationship of the coronary arterial tree (vessels >0.5 mm in diameter) were determined using a video densitometric technique in the range of +150 to -150 mmHg. The vasodilated left anterior descending (LAD) coronary artery of six KCl-arrested hearts were perfused with iodine and 3% Cab-O-Sil. The intravascular pressure was varied in a triangular pattern, whereas the absolute cross-sectional area of each vessel and the total arterial volume were calculated using video densitometry under different box pressures (0, 50, 100, and 150 mmHg). In the range of positive DeltaP, we found that the compliance of the proximal LAD artery in situ (4.85 +/- 3.8 x 10-3 mm2/mmHg) is smaller than that of the same artery in vitro (16.5 +/- 6 x 10-3 mm2/mmHg; P = 0.009). Hence, the myocardium restricts the compliance of the epicardial artery under distension. In the negative DeltaP range, the LAD artery does not collapse, whereas the same vessel readily collapses when tested in vitro. Hence, we conclude that myocardial tethering prevents collapse of large blood vessel under compression.     

Phytochemical potential of Daphne gnidium in inhibiting growth of melanoma cells and enhancing melanogenesis of B16-F0 melanoma

In this study, we have investigated inhibitory capacity of ethyl acetate, total oligomer flavonoid (TOF), aqueous extracts and beta amyrin acetate, a triterpene isolated from ethyl acetate extract obtained from leaves of Daphne gnidium, on mouse melanoma (B16-F0 and B16-F10 cells) proliferation. Influence of these products on percentage cell distribution in cycle phases and melanogenesis was also studied. Cell viability was determined using the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and flow cytometry was used to analyse effects of tested compounds on progression through the cell cycle. In addition, amounts of melanin and tyrosinase were measured spectrophotometrically at 475 nm. Ethyl acetate, TOF and aqueous extracts exhibited significant anti-proliferative activity after incubation with the two types of tumour skin cells B16-F0 and B16-F10. Furthermore, cell cycle analysis revealed that cells treated with ethyl acetate and TOF extracts were arrested predominantly in G2-M phase. Ethyl acetate extract has also the ability to enhance melanogenesis and tyrosinase activity of B16-F0 melanoma cells. Copyright © 2012 John Wiley & Sons, Ltd.     

Stimuli-Responsive magnetic nanoparticles for monoclonal antibody purification

Monoclonal antibodies (mAbs) are important therapeutic proteins. One of the challenges facing large-scale production of monoclonal antibodies is the capacity bottleneck in downstream processing, which can be circumvented by using magnetic stimuli-responsive polymer nanoparticles. In this work, stimuli-responsive magnetic particles composed of a magnetic poly(methyl methacrylate) core with a poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-co-AA)) shell cross-linked with N, N'-methylenebisacrylamide were prepared by miniemulsion polymerization. The particles were shown to have an average hydrodynamic diameter of 317 nm at 18°C, which decreased to 277 nm at 41°C due to the collapse of the thermo-responsive shell. The particles were superparamagnetic in behavior and exhibited a saturation magnetization of 12.6 emu/g. Subsequently, we evaluated the potential of these negatively charged stimuli-responsive magnetic particles in the purification of a monoclonal antibody from a diafiltered CHO cell culture supernatant by cation exchange. The adsorption of antibodies onto P(NIPAM-co-AA)-coated nanoparticles was highly selective and allowed for the recovery of approximately 94% of the mAb. Different elution strategies were employed providing highly pure mAb fractions with host cell protein (HCP) removal greater than 98%. By exploring the stimuli-responsive properties of the particles, shorter magnetic separation times were possible without significant differences in product yield and purity.     

Control of apple blue mould disease with Torulaspora delbrueckii in combination with Silicon

In this study, Torulaspora delbrueckii alone and in combination with silicon were evaluated for the control of apple blue mould disease caused by Penicillium expansum. In vitro, the antagonistic effects of T. delbrueckii in controlling mycelial growth of P. expansum on potato-dextrose-agar (PDA) in dual cultures, and the growth of P. expansum alone with cell-free metabolites and volatile components of T. delbrueckii were assayed. In vitro, to evaluate the direct effect of silicon on mycelial growth of pathogen, silicon at different concentrations (0.2, 0.4, 0.6, 1 and 2% (wt./vol.)) was added to PDA medium. Silicon at 0.6% (wt./vol.) and above concentrations completely inhibited the mycelial growth of P. expansum. However, it had no significant effect on population dynamics of yeast in vitro and in apple wounds. In vivo, silicon at 0.2 and 1% (wt./vol.) in combination with antagonistic yeast (1 × 10⁸ cell/ml) was a more effective approach to reduce the lesion diameter of blue mould decay of apples than the application of silicon or T. delbrueckii alone at 20 and 4°C, respectively.     

The spatial distribution of acid phosphatase activity in ectomycorrhizal tissues depends on soil fertility and morphotype, and relates to host plant phosphorus uptake

Acid phosphatase (ACP) enzymes are involved in the mobilization of soil phosphorus (P) and polyphosphate accumulated in the fungal tissues of ectomycorrhizal roots, thereby influencing the amounts of P that are stored in the fungus and transferred to the host plant. This study evaluated the effects of ectomycorrhizal morphotype and soil fertility on ACP activity in the extraradical mycelium (ACP(myc)), the mantle (ACP(mantle)) and the Hartig net region (ACP(Hartig)) of ectomycorrhizal Nothofagus obliqua seedlings. ACP activity was quantified in vivo using enzyme-labelled fluorescence-97 (ELF-97) substrate, confocal laser microscopy and digital image processing routines. There was a significant effect of ectomycorrhizal morphotype on ACP(myc), ACP(mantle) and ACP(Hartig), while soil fertility had a significant effect on ACP(myc) and ACP(Hartig). The relative contribution of the mantle and the Hartig net region to the ACP activity on the ectomycorrhizal root was significantly affected by ectomycorrhizal morphotype and soil fertility. A positive correlation between ACP(Hartig) and the shoot P concentration was found, providing evidence that ACP activity at the fungus:root interface is involved in P transfer from the fungus to the host. It is concluded that the spatial distribution of ACP in ectomycorrhizas varies as a function of soil fertility and colonizing fungus.     

Cytosolic phospholipase A2α sustains pAKT,pERK and AR levels in PTEN-null/mutated prostate cancer cells

Constitutive phosphorylation of protein kinase B (AKT) is a common feature of cancer caused by genetic alteration in the phosphatase and tensin homolog (PTEN) gene and is associated with poor prognosis. This study determined the role of cytosolic phospholipase A₂α (cPLA₂α) in AKT, extracellular signal-regulated kinase (ERK) and androgen receptor (AR) signaling in PTEN-null/mutated prostate cancer cells. Doxycycline (Dox)-induced expression of cPLA₂α led to an increase in pAKT, pGSK3β and cyclin D1 levels in LNCaP cells that possess a PTEN frame-shift mutation. In contrast, silencing cPLA₂α expression with siRNA decreased pAKT, pGSK3β and cyclin D1 levels in both PC-3 (PTEN deletion) and LNCaP cells. Silencing of cPLA₂α decreased pERK and AR protein levels. The inhibitory effect of cPLA₂α siRNA on pAKT and AR protein levels was reduced by the addition of arachidonic acid (AA), whereas the stimulatory effect of AA on pAKT, pERK and AR levels was decreased by an inhibitor of 5-hydroxyeicosatetraenoic acid production. Pharmacological blockade of cPLA₂α with Efipladib reduced pAKT and AR levels with a concomitant inhibition of PC-3 and LNCaP cell proliferation. These results demonstrate an important role for cPLA₂α in sustaining AKT, ERK and AR signaling in PTEN-null/mutated prostate cancer cells and provide a potential molecular target for treating prostate cancer.     

Identification and characterization of small molecule inhibitors of Plasmodium falciparum dihydroorotate dehydrogenase

Plasmodium falciparum causes the most deadly form of malaria and accounts for over one million deaths annually. The malaria parasite is unable to salvage pyrimidines and relies on de novo biosynthesis for survival. Dihydroorotate dehydrogenase (DHOD), a mitochondrially localized flavoenzyme, catalyzes the rate-limiting step of this pathway and is therefore an attractive antimalarial chemotherapeutic target. Using a target-based high throughput screen, we have identified a series of potent, species-specific inhibitors of P. falciparum DHOD (pfDHOD) that are also efficacious against three cultured strains (3D7, HB3, and Dd2) of P. falciparum. The primary antimalarial mechanism of action of these compounds was confirmed to be inhibition of pfDHOD through a secondary assay with transgenic malaria parasites, and the structural basis for enzyme inhibition was explored through in silico structure-based docking and site-directed mutagenesis. Compound-mediated cytotoxicity was not observed with human dermal fibroblasts or renal epithelial cells. These data validate pfDHOD as an antimalarial drug target and provide chemical scaffolds with which to begin medicinal chemistry efforts.     

Sex Ratios in a Socially Parasitic Bee and Implications for Host-Parasite Interactions

Obligate social parasites of Hymenoptera, known as inquilines, have received enormous attention due to the elaborate adaptations they exhibit for exploiting their hosts, and because they have frequently been used to infer sympatric speciation. Their population biology can be difficult to infer as they are both rare and difficult to extract from host nests. Sex allocation has been studied for very few inquilines of social Hymenoptera. Here we report sex ratio patterns in the allodapine bee Inquilina schwarzi, which is an obligate social parasite of another allodapine, Exoneura robusta. We show that the sex ratio of this inquiline varies with its brood number, it is female-biased in the smallest broods, but becomes more even in larger broods, where the population-wide sex ratio is close to parity. We argue that this pattern of bias is consistent with local resource competition, where inquiline females compete to inherit their natal colony. We also argue that extremely female-biased sex ratios of the host species, combined with overall sex ratio parity in the parasite, may help ameliorate disparity in effective population sizes between these two species which are locked in an evolutionary arms race.