Whatman chromatography paper

1–10 weeks old flies collected on the same day were used for all experiments and tested on the same day side by side. For experiments with RNAi, experimental flies and genetic controls were raised at 30°C to enhance the effect of the RNAi. Flies were tested in groups of ~60 (30 females and 30 males) in a T-maze and were allowed 1 min to make a decision to go into either arm. Experimentation was carried out within climate-controlled boxes at 25°C and 60% rH in the dark. 50 μl of fresh odor solution (all odors were purchased at Sigma-Aldrich) at different concentrations diluted in distilled water or paraffin oil applied on Whatman chromatography paper was provided in the odor tube, except for 1% CO₂, which was diluted using a custom-build setup with mass flow controller from pure CO₂ and bottled air. Control tubes were filled with 50 μl odorant solvent or compressed air in the case of CO₂. Unless otherwise indicated, 1 mM of odor dilution was used. After experimentation, the number of flies in each tube was counted. An olfactory preference index (P.I.) was calculated by subtracting the number of flies on the test odor site from the number of flies on the control site and normalizing by the total number of flies. Statistical analysis was performed using ANOVA and the Bonferroni multiple comparisons posthoc test using Prism GraphPad 6.

Different filter papers have been used in the development of paper-based sensors due to their wicking ability [31 (link),32 (link)]. Among them, Whatman chromatography paper has been the most widely used. In this study, Whatman chromatography paper No.1 with a thickness of 180 µm and grammage of 88 g/m² was selected as the basis for construction of the NiFe₂O₄/paper nanocomposite. Paper of different sizes (16 mm × 1 mm, 4 mm × 4 mm) was prepared for compounding with NiFe₂O₄ to obtain NiFe₂O₄/paper nanocomposite, as shown in Figure 1A(a). The paper was characterized by SEM, EDS, and FTIR spectra.

¹⁴C-labeled substrate oxidation to ¹⁴CO₂ was performed as described earlier^{51 (link)} with minor modifications. Cells at ~80–90% confluency were treated with rapamycin (100 nM)/torin1 (250 nM) for 24 h. Cells were then serum starved for 2 h and 0.5 μCi of radiolabeled 1-¹⁴C palmitate (BRIT, Mumbai, India) or 0.5 μCi of [¹⁴C(U)]d-glucose (Perkin-Elmer, Waltham, MA, USA) was added to 1.5 ml of media. A Whatman chromatography paper cut to the size of a 6-well plate was soaked in 3 M NaOH and placed on the lid of the plate, such that each well is covered. The cells were incubated at 37 °C for 2 h. Following the incubation, 500 μl of 70% perchloric acid was added to each well and the released CO₂ was trapped in the Whatman paper for 1 h. The filter paper was left for drying overnight and the ¹⁴C levels were estimated using a β-counter (Perkin-Elmer). Cells were scrapped and pelleted down after a brief centrifugation at 5000 r.c.f for 5 min at 4  °C. The pellet was washed two times with 1× PBS and lysed using 0.5 N NaOH, vortexed and centrifuged to isolate the cell lysate at 18 000 r.c.f. for 10 min at 4 °C. Experiments were carried out in triplicate and normalized to total cellular protein.