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34 results on '"SiMa, Yanghu"'

28. Hematopoiesis toxicity induced by 4-methylumbelliferon determined in an invertebrate model organism.

Author

Fang, Yan, He, Yue, Wang, Hua, Yan, Siqi, Xing, Rui, Yin, Weimin, Sima, Yanghu, and Xu, Shiqing

Subjects
HEMATOPOIESIS, ANTIOXIDANTS, PEPTIDE antibiotics, HEMOLYMPH, INVERTEBRATES, BLOOD cells
Abstract

Umbelliferone has potential value as it has an inhibitory effect on tumor cells; however, its impact on an animal's circulatory system and hematopoietic function has not been reported. In this study, 4-methylumbelliferon (4-MU), an umbelliferone derivative, was used as a model drug, and its potential toxicity on hemocytes and hematopoietic organs (HOs) was investigated using an invertebrate animal model, the silkworm,Bombyx mori. The results showed that the level of reactive oxygen species in HOs increased when larvae (third day of the fifth instar) were orally exposed to 4 mM 4-MU for 8 min, followed by the induction of improved antioxidative metabolism of coenzymes in hemolymph. Exposure to 4-MU also significantly upregulated the expression levels of several genes in the hemolymph and fat body (a detoxification tissue similar to the liver in mammals) including antimicrobial peptide genececropinAandmoricin, and a phagocytosis-related gene,tetraspanin E, suggesting an increased antioxidant level and antimicrobial ability of the circulatory system. However, the percentage of dead hemocytes increased and hematopoiesis significantly decreased in HOs, indicating the toxic effect of 4-MU on hemocytes and hematopoiesis, despite it inducing enhanced antioxidant and antimicrobial activity in the circulatory system. [ABSTRACT FROM PUBLISHER]

Published
2016
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34. Chitin synthase B: a midgut-specific gene induced by insect hormones and involved in food intake in Bombyx mori larvae.

Author

Zhuo W, Chu F, Kong L, Tao H, Sima Y, and Xu S

Subjects
Animals, Gastrointestinal Tract enzymology, Insect Hormones pharmacology, Larva enzymology, Larva genetics, Molting genetics, Appetite Regulation genetics, Bombyx enzymology, Bombyx genetics, Chitin Synthase genetics, Chitin Synthase metabolism, Gene Expression Regulation, Enzymologic drug effects
Abstract

Chitin synthase (CHS) is the key regulatory enzyme in chitin synthesis and excretion in insects, and a specific target of insecticides. We cloned a CHS B gene of Bombyx mori (BmChsB) and showed it to be midgut specific, highly expressed during the feeding process in the larva. Knockdown of BmChsB expression in the third-instar larvae increased the number of nonmolting and abnormally molting larvae. Exposure to nikkomycin Z, a CHS inhibitor, reduced the amount of chitin in the peritrophic membrane of molted larvae, whereas abnormally elevated BmChsB mRNA levels were readily detected from the end of molting and in the newly molted larvae. Exogenous 20-hydroxyecdysone (20E) and methoprene, a juvenile hormone analogue, significantly upregulated the expression of BmChsB when the levels of endogenous molting hormone (MH) were low and the levels of endogenous juvenile hormone (JH) were high immediately after molting. When levels of endogenous MH were high and those of endogenous JH were low during the molting stage, exogenous 20E did not upregulate BmChsB expression and exogenous methoprene upregulated it negligibly. When the endogenous hormone levels were low during the mulberry-leaf intake process, BmChsB expression was upregulated by exogenous methoprene. We conclude that the expression of BmChsB is regulated by insect hormones, and directly affects the chitin-synthesis-dependent form of the peritrophic membrane and protects the food intake and molting process of silkworm larvae., (© 2013 Wiley Periodicals, Inc.)

Published
2014
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