A predator unmasked: life cycle of Bdellovibrio bacteriovorus from a genomic perspective

Predatory bacteria remain molecularly enigmatic, despite their presence in many microbial communities. Here we report the complete genome of Bdellovibrio bacteriovorus HD100, a predatory Gram-negative bacterium that invades and consumes other Gram-negative bacteria. Its surprisingly large genome shows no evidence of recent gene transfer from its prey. A plethora of paralogous gene families coding for enzymes, such as hydrolases and transporters, are used throughout the life cycle of B. bacteriovorus for prey entry, prey killing, and the uptake of complex molecules.     

Construction and characterization of a fowlpox virus field isolate whose genome lacks reticuloendotheliosis provirus nucleotide sequences

Fowlpox virus (FWPV) has been isolated from vaccinated chicken flocks during subsequent fowlpox outbreaks that were characterized by a high degree of mortality and significant economic losses. This inability of current vaccines to induce adequate immunity in poultry could be reflective of an antigenic and/or biologic distinctiveness of FWPV field isolates. In this regard, whereas an infectious reticuloendotheliosis virus (REV) provirus is present in the majority of the field viruses' genomes, only remnants of REV long terminal repeats (LTR) have been retained in the DNAs of each vaccine strain. Although it has not been demonstrated whether the partial LTRs can provide an avenue for FWPV to reacquire the REV provirus by homologous recombination, utilizing viruses of which genomes lack any known integrated retroviral sequences could resolve concern over this issue. Therefore, such an entity was created by genetically modifying a recently isolated field strain of FWPV. This selection, in lieu of a commercial vaccine virus, as the progenitor was based on the probability that a virus circulating in the environment would be more antigenically similar to others in this locale and thus might be a better candidate for vaccine development. A comparison in vivo of the pathogenic traits of the parental wild-type field isolate, its genetically modified progeny, and a rescue mutant in whose genome the REV provirus was inserted at its previous location, indicated that elimination of the provirus sequence correlated with reduced virulence. However, even with elimination of the parasitic REV, the modified FWPV was still slightly more invasive than a commercial vaccine virus. Interestingly, both types of attenuated FWPV elicited a similar degree of antibody production in inoculated chickens and afforded them protection against a subsequent challenge by a field virus, the origin of which was temporally and geographically distinct from that of the progenitor strain. Due to its antigenicity being retained despite a decrease in virulence, this REV-less FWPV could potentially be developed as a vaccine against fowlpox.     

Surfactant effects on application of a hydrophobic, fluoropolymer coating to cotton by admicellar polymerization

Various methods have been used previously to impart hydrophobicity to cotton. In this study, thin co-polymer films of trifluoroethyl acrylate (TFEA) and octafluoro pentyl methacrylate (OFPM) were formed on cotton using individual fluorosurfactants and surfactant mixtures through the process of admicellar polymerization. Efficacy of 6 different fluorosurfactant systems and process conditions including surfactant type, concentration, adsorption/adsolubilization time, polymerization time, and monomer concentration have been investigated in order to obtain hydrophobic coatings on woven cotton fabric. Adsolubilization times as short as 2 h and polymerization times as short as 1 h yielded satisfactory performance. Characterization of the hydrophobic polymer films obtained included static contact angles, SEM imaging, elemental analysis and XPS analysis. Treated fabrics exhibited good water repellency for several surfactants and surfactant mixtures with initial supernatant monomer concentrations of 4 mM. Surfactant mixtures were able to outperform the separate individual species in admicellar polymerization.     

Endophytic colonization of white jute (Corchorus capsularis) plants by different Beauveria bassiana strains for managing stem weevil (Apion corchori)

Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales), an entomopathogenic fungus, was introduced through seed inoculation with spore suspension as an endophyte in white jute (Corchorus capsularis L.), a bast fiber crop. Out of nine B. bassiana strains, seven, viz., ITCC 6063, ITCC 4512, ITCC 4563, ITCC 5562, ITCC 4796, ITCC 5408 and ITCC 4705, became established as endophytes. The endophytic colonization was initially detected by cultivation on selective medium. Colonization was confirmed by polymerase chain reaction (PCR) using sequence characterized amplified region (SCAR) marker. Endophytic B. bassiana strains colonized in leaves of all the plants grown from treated seeds. However, the colonization frequency varied among the strains. The highest colonization frequency (70.09%) was recorded in ITCC 6063 followed by ITCC 5562 (67.67%) and ITCC 5408 (64.17%); ITCC 4512 exhibited the lowest (42.54%) colonization. ITCC 4925 and ITCC 4644 did not show any colonization. Endophytic colonization of B. bassiana reduced stem weevil infestation under pot culture. ITCC 5408 and ITCC 6063 were found most efficient, with only 10.44% and 14.06% infested plants, respectively.     

Prezygotic interspecific hybridization barriers between kenaf (Hibiscus cannabinus L.) and four wild relatives

Use of interspecific hybridization in genetic improvement of kenaf (Hibiscus cannabinus), a multipurpose crop, is limited by low cross‐compatibility. Previous hybridization studies suggest that part of incompatibility barrier is prezygotic. Pollen germination, stigma receptivity and growth of alien pollen on kenaf pistil were studied using wild relatives of kenaf. Four wild and semi‐domesticated species, H. surattensis, H. acetosella, H. radiatus and H. vitifolius, were used as pollen donors in the present experiment. H. radiatus exhibited highest pollen germination (65.89%) on H. cannabinus stigma. For closely related species (H. surattensis, H. acetosella, H. radiatus), stylar incompatibility was noticed, while for distantly related species H. vitifolius, the incompatibility was stigmatic. Number of pollen tubes entering ovule of H. cannabinus pistil was higher for H. radiatus (1.30). Alien pollen growth and penetration of pollen tube through ovule were higher in species sharing same genome of H. cannabinus. High callose deposition was observed in incompatible crosses, suggesting a general mechanism for prezygotic incompatibility in Hibiscus section Furcaria. Callose deposition in incompatible crosses increased with time.     

Sarcophine-Diol Inhibits Expression of COX-2, Inhibits Activity of cPLA2, Enhances Degradation of PLA2 and PLC��1 and Inhibits Cell Membrane Permeability in Mouse Melanoma B16F10 Cells

Sarcophine-diol (SD) is a semi-synthetic derivative of sarcophine with a significant chemopreventive effect against non-melanoma skin cancer both in vitro and in vivo. Recently, we have studied the effect of SD on melanoma development using the mouse melanoma B₁₆F₁₀ cell line. In this study, our findings show that SD suppresses cell multiplication and diminishes membrane permeability for ethidium bromide (EB), a model marker used to measure cell permeability for Ca²⁺ ions. SD also decreases protein levels of COX-2, and increases degradation of phospholipases PLA₂ and PLC_γ1 and diminishes enzymatic activity of the Ca²⁺-dependent cPLA₂. This lower membrane permeability for Ca²⁺-ions, associated with SD, is most likely due to the diminished content of lysophosphosphatidylcholine (lysoPC) within cell membranes caused by the effect of SD on PLA₂. The decrease in diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP₃) due to inhibition of PLC_γ1, leads to the downregulation of Ca²⁺-dependent processes within the cell and also inhibits the formation of tumors. These findings support our previous data suggesting that SD may have significant potential in the treatment of melanoma.     

Identification of genomic locations associated with grain micronutrients (iron and zinc) in rice (Oryza sativa L.)

Genetic Resources and Crop Evolution - In this investigation, recombinant inbred lines (RILs) population derived from PAU 201 (high yielding) and Palman 579 (high iron and zinc content) varieties...     

Molecular identification of a Candidatus phytoplasma (Group16SrV-D) coding partial uvrB gene and degV gene on a new host – mesta (Hibiscus sabdariffa) – with phyllody and reddening of leaves in India

Mesta (Hibiscus sabdariffa) is an important bast fiber crop. In August 2011, there was an outbreak of a phytoplasma-like disease on H. sabdariffa in different villages of the northern coastal mesta-growing region of Andhra Pradesh, India, covering mainly two districts – Srikakulam and Vijayanagaram. The infected plants showed characteristic symptoms such as phyllody and reddening of leaves. PCR with P1/P7 universal primer pair of 16 S rDNA yielded amplicons of 1850 bp from all symptomatic mesta leaf samples similar to samples of brinjal little leaf (phytoplasma positive reference control). However, asymptomatic samples were not amplified. Multiplex nested-PCR showed simultaneous amplification of DNA fragments with phytoplasma specific primers, viz., P1/P7 universal primer pair of 16 S rDNA, nested primer pair R16F2n/R2, uvrB and DegV gene-specific uvrB-degVF/R primer generating amplicons of 1850 bp, 1200 bp and 1023bp, respectively. However, SecY-map gene specific primer SecY-mapF/R was not amplified. The 1023 bp nucleotide sequence of uvrB and DegV gene of the phytoplasma was deposited in the GenBank (NCBI) with the accession no. JX975061. NCBI BLASTn analysis of the 1023 bp products showed that the phytoplasma strain belonged to elm yellows group (16SrV-D). This is the first report that Hibiscus sabdariffa is infected by a phytoplasma and we named it mesta phyllody disease (MPD).     

Identification and characterization of fowlpox virus strains using monoclonal antibodies.

The use of 2 monoclonal antibodies (MAbs), P1D9 and P2D4, which recognize different fowlpox virus (FPV) antigens, for the identification and characterization of FPV strains was evaluated. Initially, the MAbs were used in conjunction with a dot blot assay that enabled FPV to be differentiated from the avian herpesvirus, infectious laryngotracheitis virus. Confirmation of the specificity of these MAbs was provided by the demonstration that only FPV antigens were recognized by a combination of both antibodies when used for immunoblotting proteins contained in various avipoxviruses. Later, an antigenic characterization of 11 FPV field isolates, 6 FPV vaccine strains, and 3 pigeonpox virus vaccines was performed by Western blotting with the individual MAbs. Whereas MAb P2D4 consistently recognized a protein with an apparent molecular weight of 60 kD, there was variability in the size of the antigen that was immunoreactive with the other MAb. For example, MAb P1D9 recognized an antigen of apparent molecular weight of 46 kD in all vaccine strains except 2 of FPV origin. In these exceptions, either only a 39-kD or both a 42- and 46-kD protein were immunoreactive. As for the field isolates, a 39-kD antigen was recognized in 8 of them, whereas a 42-kD antigen was detected in the remaining 3. Therefore, the more extensive immunoblotting technique may facilitate FPV strain differentiation, whereas routine diagnosis of fowlpox could be accomplished by using the MAb-based dot blot assay.