tailieunhanh - Báo cáo khoa học: Insect cytokine, growth-blocking peptide, is a primary regulator of melanin-synthesis enzymes in armyworm larval cuticle

The cuticles of most insect larvae have a variety of melanin patterns that function in the insects’ interactions with their biotic and abiotic environ-ments. Larvae of the armywormPseudaletia separatahave black and white stripes running longitudinally along the body axis. This pattern is empha-sized after the last larval molt by an increase in the contrast between the lines. | ễFEBS Journal Insect cytokine growth-blocking peptide is a primary regulator of melanin-synthesis enzymes in armyworm larval cuticle Yosuke Ninomiya1 and Yoichi Hayakawa2 1 Graduate Schoolof EnvironmentalEarth Science Hokkaido University Sapporo Japan 2 Department of Applied BiologicalScience Saga University Japan Keywords calcium ion epidermal cell growth-blocking peptide insect uric acid Correspondence Y. Hayakawa Department of Applied BiologicalScience Saga University Honjo-1 Saga 840-8502 Japan FaX Tel 81 952 28 8747 E-mail hayakayo@ Received 20 December 2006 revised 20 January 2007 accepted 1 February 2007 doi The cuticles of most insect larvae have a variety of melanin patterns that function in the insects interactions with their biotic and abiotic environments. Larvae of the armyworm Pseudaletia separata have black and white stripes running longitudinally along the body axis. This pattern is emphasized after the last larval molt by an increase in the contrast between the lines. We have previously shown that 3 4-dihydroxy-L-phenylalanine Dopa decarboxylase DDC is activated during the molt period by preferential enhancement of its transcription in the epidermal cells beneath the black stripes. This study demonstrated that tyrosine hydroxylase TH expression is activated synchronously with DDC. Furthermore enhancement of DDC and TH transcription is due to an increase in cyotoplasmic Ca2 which is induced by the insect cytokine growth-blocking peptide GBP . Enhanced gene expression for both enzymes was induced by substitution of the calcium ionophore A23187 and completely blocked by EGTA. A GBP-induced increase in cytoplasmic Ca2 was seen in epidermal cells under the black stripes but not those beneath the white stripes suggesting that a difference in Ca2 concentration in stripe cells leads to the specific expression of DDC and TH genes. Based on the fact that epidermal cells beneath the white stripes contain .