Cellular expression of the pepsinogen and gastric proton pump genes in the stomach of winter flounder as determined by in situ hybridization

Abstract

The sites of pepsinogen synthesis and hydrochloric acid secretion were localized in the glandular stomach mucosa of winter flounder using in situ hybridization with gastric‐specific, biotinylated antisense RNA probes for three genes: pepsinogen IIa, pepsinogen IIb and the a‐subunit of the proton pump (H+/K+‐ATPase). The spatial expression patterns of the pepsinogen IIa and IIb genes appeared to be the same, but they differed from that of the ‐proton pump gene. The gastric gland cells contained transcripts (mRNAs) of all three genes, whereas the mucous neck cells and surface mucous cells contained transcript of the a‐proton pump only. The expression of the pepsinogen IIa, pepsinogen IIb and α‐proton pump gene in the same gastric gland cells indicates that these cells synthesize pepsinogens and secrete hydrochloric acid simultaneously and confirms that they are of the oxynticopeptic type. The presence of the a‐proton pump mRNA in the mucous neck and surface mucous cells, shown here for the first time, indicates that these cells are capable of secreting hydrochloric acid. The physiological importance of hydrochloric acid secretion by these two cell types remains unknown.

Development of digestive enzyme activity in larvae of spotted sand bass Paralabrax maculatofasciatus II: Electrophoretic analysis

“…These discrepancies in the results could be attributed to the different techniques (histological vs. biochemical) or dissimilar culturing conditions. Díaz-López et al (1998) and Gawlicka et al (2001) reported that pepsin activity occurs when larvae become juveniles and the stomach becomes functional. One suggestion is that, prior to the development of pepsin activity, alkaline proteases are responsible for protein digestion and that this activity is reduced when pepsin increases (Ribeiro et al 1999).…”

Dietary acidification enhances phosphorus digestibility but decreases H+/K+-ATPase expression in rainbow trout

“…Oxynticopeptic cells contain abundant zymogen granules (Garrido et al, 1993) or large intracellular vacuoles (Bomgren et al, 1998) or cavities (Garrido et al, 1996) and secrete both hydrochloric acid and protein. Oxynticopeptic cells are located mainly in the corpus of the stomach and are embedded in glands within the lamina propria as described in the winter flounder, European eel, rainbow trout and Atlantic stingray (Garrido et al, 1996;Garrido et al, 1993;Gawlicka et al, 2001;Smolka et al, 1994). Because oxynticopeptic cells are not specialized, they are thought to be less efficient in secreting acid than mammalian parietal cells (Koelz, 1992;Vial and Garrido, 1979).…”

A putative H+-K+-ATPase in the Atlantic stingray,Dasyatis sabina: primary sequence and expression in gills

“…Although our immunoreactivity results suggest the expression of an HK␣1-like protein in stingray stomachs and gills, we could not make any definitive conclusions about the identity of these putative HK␣1-like proteins based on these results alone. Before this study, the most ancestral organism for which HK␣1 sequence data existed was a teleost (Pleuronectes americanus) (18), and it was not known if an orthologue of HK␣1 existed in elasmobranchs. In addition, although the HK␣1 antibodies did not appear to react with NaK␣ on Western blots or in rectal glands of stingrays, the possibility of crossreactivity with other type IIc P-ATPases could not be eliminated because all the type IIc P-ATPases share homology.…”

“…H ϩ -K ϩ -ATPase has also been predicted to function in secretion of acid in fish stomachs, but the evidence is sparse. For example, although teleosts and elasmobranchs are known to secrete acid from their stomachs (23), the only fish sequence data in GenBank is an HK␣1-like cDNA fragment from the stomach of a teleost fish, Pleuronectes americanus (AW013156) (7,18). The only evidence in an elasmobranch is a study that detected immunoreactivity for HK␣1 in gastric oxyntic cells of the Atlantic stingray (Dasyatis sabina) (43).…”