Four larvae at stage G42 from controls and nitrate treatments
were collected respectively. Tissues, including tail, hind-limb and
intestine, were obtained from larvae. Tissues were treated with liquid
nitrogen, and then stored at 80 C for extracting total RNA.
Total RNA from tissues were extracted using E.Z.N.A.TM tissue
RNA Kit (Omega). RNA quality was confirmed by the ratio of O.
D. absorbencies 260/280 nm and electrophoresis on a 1.5% agarose
gel with ethidium bromide-stained. RNA quantification was measured
through UV spectrophotometry at 260 nm using Nano
Drop instrument (Thermo). Approximately 2 lg RNA was reverse
transcribed into complementary DNA (cDNA) using the high capacity
cDNA reverse transcription kit (BioRT Two Step RT-PCR Kit). The
PCR amplifications were performed in 25 ll reaction mixture containing
100nM of dNTP mixture, 2 ll of cDNA solution as template,
10PCR buffer (Mg2+), specific primers, Taq mix DNA polymerase
(Takara) and also distilled water. PCR was carried out as the following
parameters: 94 C 3 min, 30 cycles of 94 C 30 s,
52 C 30 s, 72 C 1 min.