Download 42(5): 551-557. 2010 Insecticidal activities of essential oils from

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
Abstract
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
Abstract
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 storedgrain 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 twocomponent 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
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
b
Abstract
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 Thr167, 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
Abstract
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 phosphatelimiting 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
Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok
10330, Thailand
b
Abstract
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 Nterminal 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.
Keywords
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