Immunohistochemical localization of a H2S-generating enzyme and its potential molecular target in hepatopancreas of the freshwater crayfish Procambarus clarkii

ABSTRACT There is increasing evidence showing that the gasotransmitter hydrogen sulfide (H2S) and NF-κB-mediated signaling may play an important role in regulating immune response. However, essentially nothing is known about them in crustaceans, especially the red swamp crayfish (Procambarus clarkii). In this work, we used immunohistochemical method to investigate, for the first time, the presence and distribution of a H2S biosynthetic enzyme (cystathionine β-synthase, CBS) and a member of NF-κB family (RelA/p65) in crayfish hepatopancreas. Results indicated that (1) CBS-like and NF-κB p65-like immunopositive cells coexisted in hepatopancreas; (2) NF-κB p65 was diffusely localized and highly expressed in the cytoplasm of R- and B-cells, but CBS was observed mainly in connective tissue, especially in sinusoids; (3) and normally, at mean optical density (MOD) level, their expression was about 0.0032 ± 0.0028 and 0.0072 ± 0.0039, and proportion (%) of positive cells was 14.37 ± 5.76 and 23.5 ± 14.3, respectively.