title: Apolipophorin III and transmission electron microscopy as toxicity indicators for harmaline and tea saponin in Spodoptera exigua (Noctuidae: Lepidoptera).
abstract: Apolipophorin III, traditionally known for lipid transport in insects is fairly established as toxicity indicator against harmaline and tea saponin during this study. Apolipophorin III expressed in the hemolymph and midgut tissues of 3rd, 4th, 5th larval instars and pupae of Spodoptera exigua. Apolipophorin III presence was further confirmed by achieving its partial cDNA (Genbank accession no. FJ606822) of 448bp. qRT PCR revealed that tea saponin resulted in significant reduction of gene expression in 3rd and 4th larval instars but increased in 5th instar as compared to control. Harmaline caused gradual increase of gene expression in 3rd, 4th and 5th instars after feeding on the treated diet. Fifth instar larvae synonymously resulted in the highest gene expressions against both the biochemicals. After the injection of harmaline and tea saponin abrupt increase in gene expression of 4th, 5th larval instar and pupae was observed as compared to control treatment. Transmission electron microscopy of midgut epithelium after being fed with harmaline and tea saponin depicted certain cytological changes. Harmaline treatment lead to cytoplasm vacuolization, mitochondrial disruption, spherocrystals with concentric layers, irregular nucleus and floating nuclei in cytoplasm. Tea saponin treatment resulted in denser cytoplasm, higher intracellular osmotic concentration and reduced complement of apical microvilli. Cells were found to have only a few mitochondria and glycogen deposits in comparison to control treatment.
authors.affiliation: Key Laboratory of Natural Pesticide and Chemical Biology, South China Agriculture University, Ministry of Education, Guangzhou 510640, People's Republic of China.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Rizwan-ul-Haq
authors.forename: Liang
authors.initials: L
authors.lastname: Gong
authors.forename: Meiying
authors.initials: M
authors.lastname: Hu
authors.forename: Jianjun
authors.initials: J
authors.lastname: Luo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001053:Apolipoproteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D005786:Gene Expression Regulation / Q000187:drug effects; D006246:Harmaline / Q000633:toxicity*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D010802:Phylogeny; D012503:Saponins / Q000633:toxicity*; D017422:Sequence Analysis, DNA; D018411:Spodoptera / Q000187:drug effects* / Q000235:genetics / Q000648:ultrastructure; D013662:Tea / Q000737:chemistry*; D018675:Toxicity Tests / Q000379:methods*
chemical_list: D001053:Apolipoproteins; D012503:Saponins; D013662:Tea; C042470:apolipophorin III; D006246:Harmaline