Fig. 1

Generation of rhLF transgenic silkworm. a Structural map of the transgenic vector. 3xp3RFP represents the selection marker of the transgene; SV40 indicates the termination codon sequence of sericin1 gene; Ser1 represents the promoter region of the sericin1 gene; Ser1PA indicates the poly A sequence of the sericin1 gene. b SDS-PAGE analysis of the cocoon proteins from 13 different transgenic lines. Lane 1–13, 13 transgenic cocoon sericin extracts; M and WT represent the marker and wild type samples, respectively. c Western blot analysis of rhLF in sericin crude extract from number 1–13, the thicker strip indicates the higher rhLF content. The individual with the highest rhLF content was selected to established the rhLF transgenic line. d The insertion site of the rhLF gene on the chromosome of the transgenic silkworm. The highest expression level of the rhLF transgenic silkworm was determined, and then backcross with a normal moth, its offspring were used for insertion site detection after the establishment of the silkworm strain. e The insertion site of the transgene in the rhLF transgenic silkworm genome, the target sequence “TTAA” specifically recognized by piggyBac transposase is highlighted in red