The ovicidal, larvacidal and adulticidal properties of 5,5'-Dimethyl-2,2'-Bipyridyl against Drosophila melanogaster

Insecticide resistance has limited the number of available chemical options for insect pest control. Hence there is a need for new chemistries with novel modes of action. Here we investigate the mode of action for an insecticide that has not yet been released for commercial use. The ovicidal, larvacidal and adulticidal effects of 5,5'-dimethyl -2, 2'-dipyridyl (termed Ha44), which is being developed as a treatment for head lice, were evaluated in the Drosophila melanogaster model system. Ha44 demonstrated significant activity against embryos and was capable of arresting development at a number of stages of embryogenesis. The effects of Ha44 on embryos was shown to be reversible following the addition of the metal ions Fe(II) and Fe(III), Cu and Zn. When larvae were exposed to Ha44, lethality was recorded at similar concentrations to those observed for embryos. Using an eYFP reporter system it was shown that Ha44 was able to reduce the levels of both copper and zinc in the digestive tract, confirming the binding of Ha44 to these metals in vivo. Ha44 has further been shown to inhibit a zinc containing metalloproteinase in vitro. Exposure of adult flies to Ha44 resulted in lethality, but at higher concentrations than those observed for embryos and larvae. The median lethal dose in adult flies was shown to be associated with the type of exposure, with an LD-50 of 1.57 mM being recorded following the direct contact of flies with Ha44, while an LD-50 of 12.29 mM was recorded following the ingestion of the compound. The capacity of Ha44 to act on all stages of the life-cycle and potentially via a range of targets suggests that target site resistance is unlikely to evolve

Intention to accept pertussis vaccine among pregnant women in Karachi, Pakistan

Background: Maternal immunization against pertussis is a potential strategy to protect young infants from severe disease. We assessed factors associated with intention to accept pertussis vaccination among pregnant women in Karachi, Pakistan.Methods: We conducted a cross-sectional survey between May and August 2013 in pregnant women who visited healthcare centers in urban slums of Karachi city. Women completed a survey examining socio-demographic factors, vaccination history, knowledge on pertussis disease, perception of vaccine recommendation sources, and potential influences on vaccine decision-making.Results: Of the 283 participants, 259 (92%) provided their intention to either accept or decline pertussis vaccination. Eighty-three percent women were willing to accept the pertussis vaccine if offered during pregnancy. About half (53%) of the participants had ever heard of pertussis disease. Perceptions of pertussis vaccine efficacy, safety, and disease susceptibility were strongly associated with intention to accept pertussis vaccine (p \u3c 0.01). Healthcare providers, Ministry of Health, and mass media were considered as highly reliable sources of vaccine recommendation and associated with intention to accept antenatal pertussis vaccination (p \u3c 0.001). Healthcare provider recommendation was a common reason cited by respondents for pregnant women to accept antenatal pertussis vaccination (p = 0.0005). However, opinion of primary decision-makers in the family (husbands and in-laws) was a crucial reason cited by respondents for pregnant women to reject pertussis vaccination in pregnancy (p = 0.003). Conclusion: Antenatal pertussis vaccination initiatives in South Asia should strongly consider inclusion of family members, healthcare providers, national health ministries, and mass media to help implement new vaccination programs

Molecular basis of adaptive shift in body size in Drosophila melanogaster : functional and sequence analyses of the Dca gene

Latitudinal body size clines in animals conforming to Bergmann's rule occur on many continents but isolating their underlying genetic basis remains a challenge. In Drosophila melanogaster, the gene Dca accounts for approximately 5–10% of the natural wing size variation (McKechnie SW, Blacket MJ, Song SV, Rako L, Carroll X, Johnson TK, Jensen LT, Lee SF, Wee CW, Hoffmann AA. 2010. A clinally varying promoter polymorphism associated with adaptive variation in wing size in Drosophila. Mol Ecol. 19:775–784). We present here functional evidence that Dca is a negative regulator of wing size. A significant negative latitudinal cline of Dca gene expression was detected in synchronized third instar larvae. In addition, we clarified the evolutionary history of the three most common Dca promoter alleles (Dca237-1, Dca237-2, and Dca247) and showed that the insertion allele (Dca247), whose frequency increases with latitude, is associated with larger wing centroid size and higher average cell number in male flies. Finally, we showed that the overall linkage disequilibrium (LD) was low in the Dca promoter and that the insertion/deletion polymorphism that defines the Dca alleles was in strong LD with two other upstream sites. Our results provide strong support that Dca is a candidate for climatic adaptation in D. melanogaster.10 page(s

An <i>MtnB-eYFP</i> reporter (green fluorescent signal) indicates relative copper and zinc content in midguts from dissected third instar larvae.

<p>Larvae were reared on normal food (NF) or food containing 1 mM Cu or Zn. Expression of eYFP was inhibited by addition of 0.1 mM Ha44. Red arrows indicate regions with lower eYFP expression. Pictures of every condition were taken with light (top) and fluorescence filter (bottom).</p

Effect of different metals on hatching of Ha44-exposed embryos.

<p>Freshly laid embryos (0–2 hours) were exposed to a lethal dose of Ha44 in the absence/presence of metals [Cu, Zn, Fe(II) and Fe(III)] at different concentrations (mM). Possible significant differences in potency between the different metals were assessed using a two-way ANOVA model combined with a Bonferroni post hoc test (*** = p&lt;0.0001, n.s. = not significant).</p

Dose response effect of Ha44 on larval development.

<p>Concentration of Ha44 (mM) to which first instar larvae were exposed in function of mortality (50 larvae/condition). For each concentration the average mortality (percentage) is presented±S.E. The legend below the graph displays the LD-50 and −90 values (mM) for Ha44 at a 95% significance level according to Probit.</p

<i>In vitro</i> inhibitory potency of Ha44:

<p><b>Panel (A).</b> zymogram. Lane 1 and 2 are controls, in lane 3 active meprin 1A is visualised (148 KDa) and lane 4 displays the inhibitory effect of Ha44 on meprin 1A. <b>Panel (B):</b> azocasein (1%) assay. Inhibitory effect (%) of Ha44, TPEN and EDTA (1 mM) on activated meprin 1A compared to a control condition (0% inhibition).</p