In addition, two earlier developmental stages (stages 10 and 7;
Ojeda et al., 2012a,b) were analyzed for two species, L. japonicus
and L. berthelotii with the purpose of characterizing the early gene
expression of the same set of genes. RNA was extracted using the
Pure LinkTM Plant RNA Reagent from Invitrogen following the manufacturer’s
protocol. RNA was treated with DNAse, visualized on an
agarose gel (2%) and its concentration measured using a Nanodrop
spectrophotometer (ND-1000 Spectrophotometer, Thermo Scientific).
RNA was converted to cDNA using similar amount of RNA
across all the samples using the RevertAidTM H Minus First Strand
cDNA Synthesis Kit from Fermentas using a random hexamer
primer according to manufacturer’s protocol. Genomic contamination
was assessed using the CYCLOIDEA 2 (LjCYC2) intron in L.
japonicus. The initial amount of cDNA was adjusted for each sample
analyzed and an internal control of endogenous expression was
assessed by the constitutive expression of L. japonicus Ubiquitin
(LjUbi) using LjUbiF/R (Feng et al., 2006).