Quorum sensing activity of the plant growth-promoting rhizobacterium <Emphasis Type="Italic">Serratia glossinae</Emphasis> GS2 isolated from the sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) rhizosphere

Plant growth-promoting rhizobacteria (PGPR) affect plant growth through various mechanisms, such as indole-3-acetic acid (IAA) production, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, and biofilm formation. The aim of the study reported here was to isolate and characterize rhizobacteria that produce quorum-sensing signal molecules and other PGPR-related molecules. A biofilm-forming bacterium, GS2, was isolated from the rhizosphere of a sesame plant and subsequently found to produce two quorum-sensing signal molecules that were identified as N-hexanoyl-L-homoserine lactone (m/z 200) and N-octanoyl-L-homoserine lactone (m/z 228) by liquid chromatography–tandem mass spectrometry analysis. The strain was also found to produce IAA (17.2 μg mL^?1), gibberellins (113.7 μg mL^?1), and ACC deaminase (9.7 μM α-ketobutyrate mg^?1 protein h^?1). The strain was identified as Serratia glossinae based on a comparison of 16S rRNA gene sequences. Inoculation of the strain promoted growth of a gibberellin-deficient rice dwarf mutant (Waito-C). Different growth attributes, including shoot and root elongation, chlorophyll content, and plant weight could be attributed to the PGPR characteristics of strain GS2. These results suggest that S. glossinae strain GS2 can serve as a microbial agent that improves plant growth.     

Small phosphatidate phosphatase (<Emphasis Type="Italic">TtPAH2</Emphasis>) of <Emphasis Type="Italic">Tetrahymena</Emphasis> complements respiratory function and not membrane biogenesis function of yeast <Emphasis Type="Italic">PAH1</Emphasis>

Phosphatidate phosphatases (PAH) play a central role in lipid metabolism and intracellular signaling. Herein, we report the presence of a low-molecular-weight PAH homolog in the single-celled ciliate Tetrahymena thermophila. In vitro phosphatase assay showed that TtPAH2 belongs to the magnesium-dependent phosphatidate phosphatase (PAP1) family. Loss of function of TtPAH2 did not affect the growth of Tetrahymena. Unlike other known PAH homologs, TtPAH2 did not regulate lipid droplet number and ER morphology. TtPAH2 did not rescue growth and ER/nuclear membrane defects of the pah1? yeast cells, suggesting that the phosphatidate phosphatase activity of the protein is not sufficient to perform these cellular functions. Surprisingly, TtPAH2 complemented the respiratory defect in the pah1? yeast cells indicating a specific role of TtPAH2 in respiration. Overall, our results indicate that TtPAH2 possesses the minimal function of PAH protein family in respiration. We suggest that the amino acid sequences absent from TtPAH2 but present in all other known PAH homologs are critical for lipid homeostasis and membrane biogenesis.     

Sequence analysis and characterization of vacuolar-type H+ -ATPase proteolipid transcript from Acanthus ebracteatus Vah1.

The vacuolar-type H+ -ATPase (V-ATPase) is a multimeric enzyme with diverse functions in plants such as nutrient transport, flowering, stress tolerance, guard cell movement and development. A partial sequence of V-ATPase proteolipid was identified among the expressed sequence tags (ESTs) generated from Acanthus ebracteatus, and selected for full-length sequencing. The 876-nucleotide cDNA consists of an open reading frame of 165 amino acids. The deduced amino acid sequence displays high similarity (81%) with its homologs from Arabidopsis thaliana, Avecinnia marina and Gossypium hirsutum with the four transmembrane domains characteristics of the 16 kDa proteolipid subunit c of V-ATPase well conserved in this protein. Southern analysis revealed the existence of several members of proteolipid subunit c of V-ATPase in A. ebracteatus. The mRNA of this gene was detected in leaf, floral, stem and root tissues, however, the expression level was lower in stem and root tissues.     

Genetic determinants of phenotypic diversity in humans

New technologies for rapidly assaying DNA sequences have revealed that the degree and nature of human genetic variation is far more complex then previously realized. These same technologies have also resulted in the identification of common genetic variants associated with more than 30 human diseases and traits.     

Hanultarin, a cytotoxic lignan as an inhibitor of actin cytoskeleton polymerization from the seeds of Trichosanthes kirilowii

Bioactivity-directed fractionation of extracts from the seeds of Trichosanthes kirilowii led to the isolation of (-)-1-O-feruloylsecoisolariciresinol (2), named hanultarin, In addition, four known lignans were also isolated, including (-)-secoisolariciresinol (1), 1,4-O-diferuloylsecoisolariciresinol (3), (-)-pinoresinol (4), and 4-ketopinoresinol (5). Their structures were elucidated on the basis of spectroscopic data. Compounds 2 and 3 exhibited strong cytotoxic effects against human lung carcinoma A549 cells, melanoma SK-Mel-2 cells, and mouse skin melanoma B16F1 cells with IC(50) ranges of 3-13 microg/mL. Compound 2 showed an inhibitory effect on the polymerization of the actin cytoskeleton in normal epidermal keratinocyte (HaCaT cells), suggesting unique biological properties of compound 2 compared to those of the other isolates.     

Molecular characterization of Pasteurella multocida isolates from rabbits

Forty isolates of Pasteurella multocida from healthy (17 isolates) and diseased (23 isolates) rabbits were assayed for the presence of plasmids in seeking to determine whether any correlation exists between the presence of plasmids and health status, sensitivity to antimicrobial agents, capsular and somatic type, and the anatomic site of isolation. Six isolates were found harboring plasmids. A similar ladder pattern ranging from 18 to 3 megadalton (Mda) were found in three isolates recovered from diseased rabbits. One band of molecular weight 6.6 Mda was shared by four of five (4/5) isolates from the diseased rabbits. No correlation was found between the presence of the common plasmids and serotype, resistance to antimicrobial agents, and anatomic sites from which the bacteria were cultured. Random amplification polymorphic DNA was applied to subtype all the isolates of P. multocida. Two single primers were tested for their abilities to generate individual fingerprints by using PCR. Primer 1 grouped the isolates into 7 profiles, and primer 2 grouped them into 15. Random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) results show the presence of a wide heterogeneity within P. multocida isolates. Therefore RAPD-PCR is an efficient technique to detect the DNA polymorphism and could be used to discriminate P. multocida of rabbit isolates together with serologic typing.     

Laboratory evaluation of some plant essences to control Varroa destructor (Acari: Varroidae)

This research was conducted to evaluate acaricidal effects of some plant essences on Varroa mites and the possibility of their usage for Varroa control. First, live Varroa mites were obtained from adult honeybees with CO₂ in a newly designed apparatus. Thyme, savory, rosemary, marjoram, dillsun and lavender essences at concentrations of 2 and 1g/100g (w/w), caused a mite mortality rate of more than 97% and 95%, respectively. Also spearmint at 2g/100g was able to kill more than 97% of Varroa mites. When sprayed on worker honeybees infected with mites, thyme, savory, spearmint and dillsun essences at 2g/100g (w/w) caused 43–58% Varroa mortality. Toxicity of thyme, savory and spearmint essences for worker honeybees was not significantly different from that of controls (acetone and water), but dillsun essence caused 12% honeybee mortality. These results showed that essences of thyme, savory and spearmint have acaricidal properties that could be used for controlling Varroa in honeybee colonies. This revised version was published online in July 2006 with corrections to the Cover Date.     

PRIMA-1 induces apoptosis by inhibiting JNK signaling but promoting the activation of Bax

The p53 protein plays a major role in the maintenance of genome stability in mammalian cells. Mutations of p53 occur in over 40% of breast cancers and are indicative of tumor resistance to chemotherapeutic agents. Recently, there has been a high degree of interest in pharmacological approaches for restoring the normal function to mutant p53. The low molecular weight compound p53 reactivation and induction of massive apoptosis (PRIMA-1) was shown to induce cytotoxic effects and apoptosis in human tumor cells with mutant p53. Here, we studied the molecular mechanisms of PRIMA-1-induced apoptosis in human breast cancer cells with p53 mutations such as MDA-231 and GI-101A as compared to MCF-7 cells. We show that PRIMA-1 selectively induces apoptosis in human breast cancer cells MDA-231 and GI-101A compared to the MCF-7. This effect was paralleled by an increase in total p53 level in the nucleus and the induction of its phosphorylation at Ser-15 site. Using the chromatin immunoprecipitation (ChIP) assays, we show that PRIMA-1 restored p53 DNA binding activity to the promoters of the proapoptotic genes such as Bax and PUMA, but inhibited the binding activity to the promoters of the MAP4K4 gene. Knockdown of p53 protein in breast cancer cells using siRNA followed by PRIMA-1 treatment resulted in decline of Bax and PUMA proteins expression. Cell incubation with either PRIMA-1 or SP600125 (c-Jun NH2-terminal kinase inhibitor) resulted in the abrogation of adriamycin-induced c-Jun NH2-terminal kinase (JNK) activation, whereas Bax activation was not inhibited. We conclude that both Bax and PUMA but not JNK signaling are involved in PRIMA-1-induced apoptosis in breast cancer cells with p53 mutation.     

Effective syntheses of 2′,4′-BNANC monomers bearing adenine,guanine, thymine,and 5-methylcytosine,and the properties of oligonucleotides fully modified with 2′,4′-BNANC

We efficiently synthesized 2′-O,4′-C-aminomethylene-bridged nucleic acid (2′,4′-BNA^NC) monomers bearing the four nucleobases, guanine, adenine, thymine, and 5-methylcytosine and incorporated these monomers into oligonucleotides. Initially, we carried out the transglycosylation reaction on several 2′-O-substituted 5-methyluridines to evaluate the effects of 2′-substitutions on this reaction. Under the optimized conditions, purine nucleobases were successfully introduced, and 2′,4′-BNA^NC monomers bearing adenine or guanine were obtained over several steps. In addition, the improved synthesis of the 2′,4′-BNA^NC monomers bearing thymine or 5-methylcytosine was also achieved. The obtained 2′,4′-BNA^NC monomers were subsequently incorporated into oligonucleotides and the duplex-forming abilities of the modified oligonucleotides were investigated. Duplexes containing 2′,4′-BNA^NC monomers in both or either strands were found to possess excellent thermal stabilities.     

All-Optical Cross-Bar Switch Based on a Low-Loss Suspended Graphene Plasmonic Coupler

Plasmonics - Graphene-based optical switches are one of the promising building blocks for future optical integrated circuits. For the first time in this paper, a novel all-optical graphene-based...