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Fold Allethrin Fenitrothion ‰ = ‰ > ‰ > ‰ = ‰ = ‰ > ‰ > Males and females do not always show the same sensitivity to pesticide exposure. In the case of aldicarb and allethrin males and females show equal sensitivity; however upon exposure to DDT and Fenitrothion males show a greater sensitivity than females in both dMRP mutant animals and controls. One way ANOVA analysis indicates that dMRP transcripts is significantly increased in wildtype adult males and females upon aldicarb exposure equal to an LD of 25%, p = .001. Tukey Pairwise Comparison supports these observations with a 95% individual confidence level. One way ANOVA analysis indicates that dMRP transcripts is significantly increased in wildtype adult males upon fenitrothion exposure equal to an LD of 25%, p = .003, and an LD of 50%, p < .001 Tukey Pairwise Comparison supports these observations with a 95% individual confidence level. Data on female response to fenitrothione currently being collected Fenitrothion yields a 1.5 fold increase in mRNA transcript expression. Aldicarb and DDT yields a 2 fold or greater increase in mRNA transcript expression. Control LD50 = .22ug, Mutant LD50 = .24ug Female control and mutant animals show no difference in senstitivity when exposed to allethrin, p=.1 Control LD50 = .34ug, Mutant LD50 = .24ug dMRP mutant females are significantly more sensitive to aldicarb than control females, p < .001 Control LD50 = .33ug, Mutant LD50 = .23ug dMRP mutant males are significantly more sensitive to aldicarb than control males, p < .001 Control LD50 = 14.6ug, Mutant LD50 = 13.9ug Male control and mutant animals show no difference in senstitivity when exposed to allethrin, p=.212 Control LD50 = .20ug, Mutant LD50 = .20ug Male control and mutant animals show no difference in senstitivity when exposed to allethrin, p=.821 Comparison of dMRP Induction in Reponse to Pesticide Exposure Male In Process Pesticide sensitivity and transcriptional regulation of the Pesticide sensitivity and transcriptional regulation of the dMRP dMRP gene, an ATP-independent efflux pump gene, an ATP-independent efflux pump Pesticide Sensitivity Assay Drosophila were exposed to four different contact pesticides: aldicarb, DDT, allethrin and fenitrothion. Each represents a different class of pesticide. After a 24 hour exposure animals were scored as live or dead. Probit analysis was used to determine if there is any significant difference in pesticide sensitivity between control animals (solid line) and dMRP mutant animals (broken line). Control Animals ‰ ∗ ∗ dMRP Gene Induction Assay Wild-type adult animals were exposed to each pesticide for a 6 hour period. After exposure RNA was extracted and RT-PCR was conducted against a standard to determine relative levels of dMRP transcripts. ANOVA and Tukey Pairwise Comparisons were used to determine if there were any significant changes in dMRP transcript levels. INTRODUCTION The dMRP gene (Drosophila multidrug resistance like protein) is orthologous to four members of the human CFTR/MRP subfamily: MRP1, MRP2, MRP3 and MRP6. dMRP encodes a 5.4 kb transcript that is ubiquitously expressed throughout embryogenesis and is head enriched in adults. Transport assays have confirmed that DMRP is capable of binding ATP and of transporting the known human MRP1 and MRP2 substrate, leukotriene C4. In order to begin to elucidate a physiological function for DMRP we have generated mutant dMRP alleles as well as transgenic dMRP RNAi animals. dMRP mutant animals are homozygous viable. Since it is well established that multidrug-resistance associated proteins are utilized for xenobiotic detoxification we are conducting bioassays to determine whether dMRP mutants are more sensitive to various xenobiotics. Additionally, we have begun to investigate the role xenobiotics may play in regulating the transcription of dMRP. Presented here are data on xenobiotic sensitivity to the contact pesticides aldicarb, DDT, allethrin and fenitrothion. These pesticides are also being investigated to determine what affect they have on the transcriptional regulation of dMRP. Preliminary data on the efficiency of the RNAi knockdown of dMRP is also presented. Allethrin Fenitrothion Control LD50 = 4.6ug, Mutant LD50 = 3.8ug dMRP mutant males are significantly more sensitive to aldicarb than control males, p = .001 Control LD50 = 5.9, Mutant LD50 = 4.8ug dMRP mutant females are significantly more sensitive to aldicarb than control females, p < .001 DDT J.N. Tarnay-Cogbill 1 , S. Robinow 2 1)Cell and Molecular Biology, University of Hawaii- Manoa, Honolulu, HI; 2) Department of Zoology, University of Hawaii- Manoa, Honolulu, HI CONCLUSIONS Pesticide Sensitivity Assay Male vs Female: Males and females showed no difference in pesticide sensitivity when exposed to allethrin or aldicarb for either the control or the dMRP mutant animals. However, a difference between male and female sensitivity was observed when animals were exposed to DDT and fenitrothion. In both cases males were more sensitive than females to the given pesticide, regardless of genotype. Wildtype vs dMRP mutant: We hypothesized that animals lacking dMRP would be more sensitive to xenobiotics because they lacked the appropriate efflux pump. dMRP mutants are more sensitive than controls to the pesticides DDT and aldicarb, but are equally sensitive to allethrin and fenitrothion. These data suggest that DDT and aldicarb, or metabolites of these compounds, may be substrates for DMRP-mediated transport. Since each of these pesticides represents a different class of pesticide we propose that DMRP transports organochlorines and carbamates, but not organophosphates or pyrethroids. Induction Assay We hypothesized that wild-type animals would accumulate dMRP transcripts in response to DDT and aldicarb exposure as it was those pesticides for which dMRP mutant animals showed an increased sensitivity. However an increase in dMRP transcripts was evident in dMRP mutants exposed to DDT and aldicarb as well as to fenitrothion. dMRP transcripts increase by greater than two fold in response to DDT and aldicarb whereas induction was less than two fold in response to fenitrothion exposure. Data on dMRP induction in response to allethrin exposure is currently being collected. Future Directions RNAi knockdown animals will be tested using the pesticide sensitivity assay to see if we can phenocopy the dMRP mutant results observed for DDT and aldicarb exposure. Transport assays will be conducted to determine if DMRP is capable of transporting any of the pesticides tested thus far. Based on the results from the pesticide sensitivity assays on dMRP mutant animals it is anticipated that DMRP will transport DDT and aldicarb but not allethrin or fenitrothion. Mutant Animals Aldicarb DDT Pesticide Sensitivity Assay - Gender Effects = One way ANOVA analysis indicates that dMRP transcripts is significantly increased in wildtype adult males and females upon DDT exposure equal to an LD of 75%, p < .001. Tukey Pairwise Comparison supports these observations with a 95% individual confidence level. ∗ ∗ ∗ ∗ Two RNAi constructs were made, one to the 5’ end of dMRP and the other to the 3’ end. Five independent dMRP RNAi transgenic lines were analyzed via Northern blot analysis for dMRP knockdown. Three of the five effectively knockdown dMRP expression: 5’ RNAi #4, 3’ RNAi #10 and 5’ RNAi #18. The contact pesticide sensitivity assay will be conducted on these animals to determine if RNAi knockdown of dMRP will phenocopy the dMRP mutant animals. RNAi knockdown of dMRP #4 Control #4 RNAi - 5’ #10 Control #10 RNAi - 3’ #12 RNAi - 5’ #18 RNAi - 5’ #12 Control #18 Control 9 6 5 4 kbp rp49 Male Female Female Male Female * * Aldicarb Male * wildtype mutant Female * mutant wildtype Control LD50 = 15.9ug, Mutant LD50 = 14.9ug Female control and mutant animals show no difference in senstitivity when exposed to allethrin, p=.122 Female Female
