|Pakistan Journal of Zoology 42(5): 551-557. 2010
Insecticidal activities of essential oils from fruits of Litsea salicifolia Roxb. ex Wall. Against Sitophilus zeamais motschulsky and tribolium castaneum (Herbst)
Ko, K.a b , Juntarajumnong, W.a , Chandrapatya, A.a
a Department of Entomology, Faculty of Agriculture, Kasetsart University, 50 Paholyothin Road, Jatuchak, Bangkok 10900, Thailand
b Plant Protection Division, Myanma Agriculture Service, Bayint Naung Road, West Gyogon, Insein P.O 11011 Yangon, Myanmar
The insecticidal activities of essential oil extracted from Litsea salicifolia to Sitophilus zeamais and Tribolium castaneum were investigated under laboratory conditions. Essential oil was extracted by hydro-distillation method and then analyzed by GC/MS. The major components of I. salicifolia were (E)-citral and (Z)-citral. Litsea salicifolia had repellency effect on both insect species even at the lowest application rate (0.16 μg/cm2). In addition, it exhibited fumigant toxicity to S. zeamais, contact toxicity to both species and high antifeedant toxicity to T. castaneum compared to 5. zeamais. Hence, L. salicifolia might be considered as a grain protectant to major stored product insects. Copyright 2010 Zoological Society of Pakistan.
Keywords: Contact toxicity; Essential oil; Fumigant; Grain protectant; Litsea salicifolia; Repellency
Kasetsart Journal - Natural Science 43(1): 56-63. 2009
Repellency, fumigant and contact toxicities of Litsea cubeba (Lour.) persoon against Stiophilus zeamais motschulsky and Tribolium castaneum (Herbst)
Ko, K.a , Juntarajumnong, W.b , Chandrapatya, A.b
a Plant Protection Division, Myanma Agriculture Service, Bayint Naung Road, West Gyogon, Yangon, Myanmar
b Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
Litsea cubeba is found in many parts of Thailand and has medicinal properties. Mature fruit of L. cubeba was collected from Doi Ang-khang, in the Fang District of Chiang Mai Province, Thailand in June 2007 and the essential oil was extracted by a water-distillation method. The insecticidal properties of L. cubeba were evaluated under laboratory conditions. The results showed that the essential oil of L. cubeba strongly repelled Sitophilus zeamais and Tribolium castaneum even at low concentrations, but its repellency was more marked toward T. castaneum. Of interest was the fact that the repellency against T. castaneum was fairly consistent over the 5 h period of the experiment. Moreover, it showed both contact and fumigant toxicities against the tested species. Probit analysis showed that S. zeamais was more susceptible than T. castaneum in both the fumigant and contact bioassays. Hence, the essential oil of L. cubeba might be used as an alternative for grain protection against stored-grain insects. Further studies are needed prior to its commercial use.
Keywords: Contact; Fumigant; Grain protection; Litsea cubeba; Repellency
Archives of Microbiology 188(4): 389-402. 2007
Phosphate sensing in Synechocystis sp. PCC 6803: SphU and the SphS-SphR two-component regulatory system
Juntarajumnong, W.a b , Hirani, T.A.a c , Simpson, J.M.a d , Incharoensakdi, A.b , Eaton-Rye, J.J.a
a Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand
b Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand
c ARC Centre for Legume Research, University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia
d Department of Molecular Medicine and Pathology, University of Auckland, Private Bag 92019, Auckland, New Zealand
The Pho regulon is controlled by the histidine kinase-response regulator pair SphS-SphR in many cyanobacteria and up-regulation of the Pho regulon can be monitored by measuring alkaline phosphatase activity. However, the mechanism regulating signal transduction between SphS and SphR has not been described. We have created a cyanobacterial strain allowing the introduction of mutations into the transmitter domain of SphS. Mutations at Thr-167, adjacent to the H motif of SphS, introduce elevated alkaline phosphatase activity in the presence of phosphate and an enhancement of alkaline phosphatase activity, when compared to the control strain, in phosphate-limiting media. SphU acts as a negative regulator of the SphS-SphR system in Synechocystis sp. PCC 6803 andwe show that constitutive alkaline phosphatase activity in the absence of SphU requires signal transduction through SphS and SphR. However, constitutive activity in the absence of SphU is severely attenuated in the ΔSphU:SphS-T167N mutant. Our data suggest that Thr-167 contributes to the mechanism underlying regulation by SphU. We have also assembled a deletion mutant system allowing the introduction of mutations into SphR and show that Gly-225 and Trp-236, which are both conserved in SphR from cyanobacteria, are essential for activation of the Pho regulon under phosphate-limiting conditions. © 2007 Springer-Verlag.
Keywords: Alkaline phosphatase; Cyanobacteria; PhoB; PhoR; Phosphate sensing; PhoU; SphR; SphS; SphU
Journal of Biochemistry and Molecular Biology 40(5): 708-714. 2007
Two-component signal transduction in Synechocystis sp. PCC 6803 under phosphate limitation: Role of acetyl phosphate
Juntarajumnong, W.a , Eaton-Rye, J.J.b , Incharoensakdi, A.a
a Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
b Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand
The two-component signal transduction, which typically consists of a histidine kinase and a response regulator, is used by bacterial cells to sense changes in their environment. Previously, the SphS-SphR histidine kinase and response regulator pair of phosphate sensing signal transduction has been identified in Synechocystis sp. PCC 6803. In addition, some response regulators in bacteria have been shown to be cross regulated by low molecular weight phosphorylated compounds in the absence of the cognate histidine kinase. The ability of an endogenous acetyl phosphate to phosphorylate the response regulator, SphR in the absence of the cognate histidine kinase, SphS was therefore tested in Synechocystis sp. PCC 6803. The mutant lacking functional SphS and acetate kinase showed no detectable alkaline phosphatase activity under phosphate-limiting growth conditions. The results suggested that the endogenous acetyl phosphate accumulated inside the mutants could not activate the SphR via phosphorylation. On the other hand, exogenous acetyl phosphate could allow the mutant lacking functional acetate kinase and phosphotransacetylase to grow under phosphate-limiting conditions suggesting the role of acetyl phosphate as an energy source. Reverse transcription PCR demonstrated that the transcripts of acetate kinase and phosphotransacetylase genes in Synechocystis sp. PCC 6803 is upregulated in response to phosphate limitation suggesting the importance of these two enzymes for energy metabolism in Synechocystis cells.
Keywords: Acetate kinase; Acetyl phosphate; Phosphotransacetylase; SphR; SphS and Synechocystis sp. PCC 6803
Current Microbiology 55(2): 142-146. 2007
Identification of the start codon for sphS encoding the phosphate-sensing histidine kinase in Synechocystis sp. PCC 6803
Juntarajumnong, W.a b , Incharoensakdi, A.b , Eaton-Rye, J.J.a
a Department of Biochemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand
b Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
In Synechocystis sp. PCC 6803 extracellular phosphate levels are relayed to the pho regulon via the SphS histidine kinase. In this cyanobacterium, the start codon of sphS has been assigned as a GUG, thereby predicting SphS to be a cytosolic protein lacking a putative N-terminal region found in the PhoR orthologue from Escherichia coli. Inspection upstream of sphS located an in-frame AUG positioned 47 codons in front of the putative GUG start. Alterations at either of the putative AUG or GUG start codons did not prevent transcription of sphS; however, up-regulation of alkaline phosphatase mRNA, or alkaline phosphatase activity, was not detected in response to phosphate-limiting conditions when the AUG was mutated. Alkaline phosphatase expression and activity serve as phenotypic markers for activation of the pho regulon. Therefore, the pho regulon had not been induced in these cells, whereas normal up-regulation was observed in strains carrying mutations at the GUG. These results show that the AUG codon, not the GUG codon, is the initiation site for sphS translation in Synechocystis sp. PCC 6803. © 2007 Springer Science+Business Media, LLC.
EMTREE drug terms: alkaline phosphatase; cytosol receptor; messenger RNA; phosphate; protein histidine kinase
EMTREE medical terms: amino terminal sequence; article; enzyme activity; gene activation; gene mutation; genetic code; genetic marker; nonhuman; prediction; priority journal; protein expression; regulon; RNA translation; start codon; Synechocystis; transcription initiation; transcription initiation site; upregulation
MeSH: Amino Acid Sequence; Bacterial Proteins; Base Sequence; Codon, Initiator; DNA, Bacterial; Gene Deletion; Genes, Bacterial; Molecular Sequence Data; Mutagenesis; Phosphotransferases; Protein Kinases; Regulon; Sequence Homology, Amino Acid; Synechocystis; Transcription Factors
Medline is the source for the MeSH terms of this document.
Species Index: Escherichia coli; Synechocystis sp. PCC 6803