Insecticidal action of mammalian galectin-1 against diamondback moth (Plutella xylostella).
BACKGROUND
Previous studies showed that mammalian galectin-1 (GAL1) could interact with chitosan or chitin, one component of the peritrophic membrane (PM). This finding suggests that the PM could be a target of GAL1, which prompted the authors to explore the effect of GAL1 on larval growth and its potential mechanism.


RESULTS
The development of Plutella xylostella (L.) larvae was significantly disturbed after they were fed recombinant GAL1. The histochemical structure and immunostaining pattern suggested that GAL1 treatment resulted in dose- and time-dependent disruption of the microvilli and abnormalities in these epithelial cells. Ultrastructural studies showed that the PM was not present in the midgut of GAL1-treated insects; instead, numerous bacteria were found in the lumen area. These results indicate that the protective function of the PM was disrupted by GAL1 treatment. Moreover, in vitro data showed that GAL1 interacts with chitosan/chitin in a dose-dependent manner, and also specifically binds to the PM in vitro.


CONCLUSIONS
In view of the fact that the carbohydrate recognition domain of GAL1 recognises the structural motif N-acetyl lactosamine (Gal beta 1-4 GlcNAc), which is similar to that of chitin (beta-1,4 N-acetyl-D-glucosamine), it is proposed that the insecticidal mechanism of GAL1 involves direct binding with chitin to interfere with the structure of the PM.
Department of Life Science, Institute of Ecology and Evolutionary Biology and TechComm-5, College of Life Science, National Taiwan University, Taipei 106, Taiwan.
Shiang Jiuun
SJ
Chen
Nien-Ting
NT
Chen
Siou-Hua
SH
Wang
Ju Chun
JC
Hsu
Wang-Hsien
WH
Ding
Ling-Long
LL
Kuo-Huang
Rong Nan
RN
Huang
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002686:Chitin / Q000378:metabolism; D048271:Chitosan / Q000378:metabolism; D037483:Galectin 1 / Q000378:metabolism / Q000494:pharmacology*; D041981:Gastrointestinal Tract / Q000166:cytology / Q000187:drug effects; D007306:Insecticides / Q000378:metabolism / Q000494:pharmacology*; D007814:Larva / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009036:Moths / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D021381:Protein Transport; D015996:Survival Rate
D037483:Galectin 1; D007306:Insecticides; D002686:Chitin; D048271:Chitosan