Meeting Abstract
P2.44 Monday, Jan. 5 Nitric oxide synthase isoforms in metamorphosis of anuran tadpoles, Xenopus laevis YAP, ANNA; VAN GURP, JAMES; MENON, JAISHRI*; William Paterson University; William Paterson University; William Paterson University menonj@wpunj.edu
Nitric oxide (NO) a signaling molecule, produce in situ by nitric oxide synthase regulate metamorphosis in some invertebrates as well as ascidians. NO has both, apoptotic and antiapoptotic properties mediated via activation of caspases and guanyl cyclase respectively. NO is also involved in cellular dynamics of regressing tail of anuran tadpoles. The objectives of the present study were to investigate a) cell specific localization for NOS using immunohistochemistry (IHS) b) if thyroid hormones control gene expression for NOS isoforms and c) changes in NO sensitive guanylyl cyclase in intestine and tail during different stages of metamorphosis of Xenopus laevis tadpoles. Immunostaining shows that, both NOS I and III are expressed in cytoplasm of epithelium and brush border of the intestine just before remodeling begins, and in epidermis of tail before regression begins. Though, there was stronger expression for NOS I than NOS III in both the tissues. NOS II was not expressed at all in either tissue. Increased apoptosis during critical period of intestinal remodeling and tail regression is associated with high expression of NOS I. RT-PCR results show that during spontaneous metamorphosis, when endogenous T3 levels are at peak, (as well as following exogenous T3 treatment) there is down regulation of NOSI in intestine. However, in tail there is up regulation of NOS I at the same stage (beginning of tail regression). Absence of guanylyl cyclase in either tissue indicates lack of NO signaling via formation of cGMP, but it may be via caspases favoring apoptosis. In conclusion, NOS(s) might be playing a crucial role as an endogenous regulator of NO signaling in intestinal remodeling and tail regression of anuran tadpoles promoting apoptosis in a tissue and/or cell specific fashion.
