Circadian Susceptibility to Circadian Susceptibility to Pyrethroids in Female Pyrethroids in Female

Drosophila melanogasterDrosophila melanogasterBy David ChinBy David Chin

Mentor: Dr. Jadwiga Giebultowicz

Relevance for ResearchRelevance for ResearchHow fruit flies metabolize toxins may How fruit flies metabolize toxins may

be:be:Different between males and femalesDifferent between males and femalesRelated to how humans metabolize Related to how humans metabolize

toxins via circadian rhythmstoxins via circadian rhythmsThese links may open up new These links may open up new

inquiries in pharmaceuticals, inquiries in pharmaceuticals, horticulture, and global economicshorticulture, and global economics

Circadian RhythmsCircadian Rhythms Internal clocks Internal clocks

that control when that control when organisms rest organisms rest and remain activeand remain active I.e. Jet lag… … … I.e. Jet lag… … … Controlled by the Controlled by the

Period and Tim Period and Tim genesgenes

http://edfredned.com/images/portfolio/Full/jetlag.gif

Circadian Clocks (cont.)Circadian Clocks (cont.)

http://www.ou.edu/wanglab/Circadianclock1/Slide1.jpg

Circadian Rhythms (cont.)Circadian Rhythms (cont.)Physiologically, they influence:Physiologically, they influence:

Hormone secretionHormone secretionOxygen consumptionOxygen consumptionMetabolismMetabolismOther functions of the bodyOther functions of the body

Point of InterestPoint of InterestCircadian rhythms may influence the Circadian rhythms may influence the

rate of metabolism of many rate of metabolism of many substances, including toxinssubstances, including toxins

The pyrethroid, deltamethrin, is The pyrethroid, deltamethrin, is administered to the female flies to administered to the female flies to investigate how they metabolize investigate how they metabolize toxins in relation to the presence and toxins in relation to the presence and absence of the circadian rhythmabsence of the circadian rhythm

PyrethroidsPyrethroids Synthetic Synthetic

insecticides insecticides derived from the derived from the flowers of flowers of pyrethrums or pyrethrums or several plants from several plants from the genus the genus ChrysanthemumChrysanthemum http://upload.wikimedia.org/wikipedia/

commons/f/fa/Chrysanthemums.jpg

DeltamethrinDeltamethrin Deltamethrin is a pyrethroid insecticide that Deltamethrin is a pyrethroid insecticide that

damages the nervous system, paralyzing the damages the nervous system, paralyzing the organisms after cuticular penetration or oral organisms after cuticular penetration or oral uptake of the neurotoxinuptake of the neurotoxin

http://upload.wikimedia.org/wikipedia/commons/3/3f/Deltamethrin-3D-balls-2.png

C22H19Br2NO3

Deltamethrin (cont.)Deltamethrin (cont.)Modifies the membrane function Modifies the membrane function

proteins and keeps the voltage-proteins and keeps the voltage-dependent sodium channels dependent sodium channels continuously opencontinuously open

Flies Being TestedFlies Being TestedCS Flies = Wild type flies with Period & CS Flies = Wild type flies with Period &

Tim genesTim genesPer-null Flies = Mutant flies that lack Per-null Flies = Mutant flies that lack

the Period gene expressionsthe Period gene expressionsCsp Flies = Backcrossed flies that Csp Flies = Backcrossed flies that

express the Period & Tim genes and are express the Period & Tim genes and are closely related to the Per-null fliesclosely related to the Per-null flies

ExperimentsExperimentsDose ResponseDose ResponseTwo Hour Interval TestTwo Hour Interval TestGST AssayGST Assay

Glutathione S-Transferases take part in Glutathione S-Transferases take part in metabolizing toxins metabolizing toxins

Mass Ratio DataMass Ratio DataAverage mass of female = 1.409 mgAverage mass of female = 1.409 mgAverage mass of male Average mass of male == 0.8103 mg 0.8103 mg

Dose Response DataDose Response DataDeltamethrin EC50

Female Male0

50

100

150 137 μg/μ l

20 μg/μ l

EC50

Deltaμethrin [

μg/μl]

Two Hour Interval Test DataTwo Hour Interval Test DataFemales

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100

Time (ZT Hours)

Mortality (%)

Two Hour Interval Test DataTwo Hour Interval Test DataMales

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100

Time (ZT Hours)

Mortality (%)

Csp and Per-Null Testing DataCsp and Per-Null Testing DataPeak and Trough Test Data in Mortality

9 pm 7am 9 pm 7am0

20

40

60

80

100

Csp Per-Null

Mortality (%)

GST Assay DataGST Assay DataFemales

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100

Time (ZT Hours)

Mortality (%)

GST Assay (Basal Activity in Females)

7 pm 9 pm 5 am 7 am0

10

20

30

40

Cs

GST Activity (nmol/min/mg)

GST Assay DataGST Assay DataMales

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100

Time (ZT Hours)

Mortality (%)

GST Assay (Basal Activity in Males)

7 pm 9 pm 5 am 7 am0

10

20

30

40

CS

GST Activity (nmol/min/mg)

Future InvestigationsFuture Investigations I will continue working on I will continue working on

investigating direct toxin applications investigating direct toxin applications and GST assays throughout the and GST assays throughout the 2007-2008 school year at Oregon 2007-2008 school year at Oregon State UniversityState University

AcknowledgementsAcknowledgementsHoward Hughes Medical InstituteHoward Hughes Medical InstituteURISCURISCDr. Kevin AhernDr. Kevin AhernDr. Jadwiga GiebultowiczDr. Jadwiga GiebultowiczEveryone in the labEveryone in the lab