Comparative transcriptomic analysis of larval and adult Malpighian tubules from the cotton bollworm Helicoverpa armigera

Malpighian tubules (MTs) are usually considered the key excretory and osmoregulatory organs of insects. However, increasing evidence has suggested that MTs perform many more functions than just osmoregulation. Until now, the molecular and physiological functions of MTs in the cotton bollworm (Helicoverpa armigera), a very important agricultural pest, are largely unknown. In this study, the transcriptomes of H. armigera MTs from larvae, male adults and female adults were sequenced using RNA-Seq technology, and comparative analyses of transcriptomes between two life stages (larval and adult) and between adult sexes were conducted. We generated a total of 84 643 high-quality unigenes, and identified a large number of abundant transcripts putatively encoding proteins involved in diuresis, detoxification, immunity, carbohydrate transport and metabolism, development and reproduction. We found that the expression pattern of unigenes was relatively similar between female and male adult MTs, but different between larval and adult MTs. Our data suggest that insect MTs may take multiple physiological functions as versatile organs. The extensive alterations in gene expression in MTs occurred from larvae to adults reflect an ecological adaptation to different feeding habits. Sexual dimorphism in the cotton bollworm is somewhat indicated by the transcriptional difference of genes related to carbohydrate metabolism, detoxification, immunity and reproduction in the MTs of male and female adults.

Proteomic-based insight into Malpighian tubules of silkworm Bombyx mori

Malpighian tubules (MTs) are highly specific organs of arthropods (Insecta, Myriapoda and Arachnida) for excretion and osmoregulation. In order to highlight the important genes and pathways involved in multi-functions of MTs, we performed a systematic proteomic analysis of silkworm MTs in the present work. Totally, 1,367 proteins were identified by one-dimensional gel electrophoresis coupled with liquid chromatography-tandem mass spectrometry, and as well as by Trans Proteomic Pipeline (TPP) and Absolute protein expression (APEX) analyses. Forty-one proteins were further identified by two-dimensional gel electrophoresis. Some proteins were revealed to be significantly associated with various metabolic processes, organic solute transport, detoxification and innate immunity. Our results might lay a good foundation for future functional studies of MTs in silkworm and other lepidoptera.