A new method for the histochemical demonstration ofO-acyl sugars in human colonic epithelial glycoproteins

Abstract

A new general method has been developed for the specific histochemical identification of O-acyl sugars in any epithelial glycoprotein. These sugars include hexose, 6-deoxyhexose and N-acetylhexosamine with an ester substituent(s) located on a potential vicinal diol(s). In the procedure reported [the periodic acid-borohydride reduction-saponification-selective periodate oxidation-borohydride reduction-periodic acid-Schiff (PA-Bh-KOH-PA*-Bh-PAS) method] the initial PA-Bh treatment renders vicinal diols located on either sialic acid or neutral sugars PAS unreactive. In the subsequent steps ester substituents are removed from both O-acyl sugars and O-acyl sialic acids by saponification (KOH), sialic acid vicinal diols are selectively removed by the PA*-Bh sequence and O-acyl sugars are stained with the PAS technique. This method has the advantage that the results are obtained with a single section and the results are either positive or negative. Consequently, it is superior to the three indirect methods investigated because it does not require an observer to compare the intensity or the shade of the staining obtained with serial sections. Using the PA-Bh-KOH-PA*-Bh-PAS method we have demonstrated, for the first time, that O-acyl sugars occur in the epithelial goblet cell glycoproteins of adult human colon. The effect of the presence of O-acyl sugars on the interpretation of a number of other methods for the histochemical investigation of glycoproteins is discussed. It is recommended that the results obtained with the PA-Bh-KOH-PA*-Bh-PAS method be evaluated before histochemical procedures for the investigation of neutral sugars and O-acyl sialic acids are selected.

Histochemical differences along the intestine of Corydoras paleatus (Siluriformes: Callichthyidae)

“…HC and LHC patterns of the mucosal layer differ among species and in different regions of the digestive tract (Reid, Volz, Cho, & Owen, 1988;Grau, Crespo, Sarasquete, & González de Canales, 1992;Leknes, 2011). In this research, a variety of GCs in the glycocalyx of I1, and a moderated to strong presence of sulfated GCs were observed.…”

Histologia e caracterização histoquímica do tubo gastrintestinal de Pimelodus maculatus (Pimelodidae, Siluriformes) no reservatório de Funil, Rio de Janeiro, Brasil

“…A ocorrência de células mucosecretoras é uma característica comum na superfície de epitélios do trato digestório de teleósteos; com as mucosubstâncias secretadas diferindo ao longo do canal alimentar dos peixes. A presença de glicoproteínas (GPs) é correlacionada com diferentes funções, como lubrificação, degradação proteolítica e inibição de microrganismos (REID et al, 1988). Neste escopo, as descrições da histologia do trato digestório são de especial interesse visando dar informações mais completas sobre todos os tipos de interferência no funcionamento de organismos vivos.…”

Immunohistochemical study of the digestive tract ofOligosarcus hepsetus

“…The secretions vary among different fish species and also according to the location in the DT within the same species [4] . These secretions play an important role in lubricating the or-gan and protecting against proteolytic degeneration and pathogenic microorganisms [5] . Besides this, to control the functions of the different DT segments, endocrine cells compose a complex system disseminated among the epithelial components, with the ability to secrete physiologically active polypeptide hormones and amines [6] .…”