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

Abstract

Abstract:The Neotropical catfish Corydoras paleatus is a facultative air-breather and the caudal half of the intestine is involved in gas exchange. In South America, air-breathing fishes are found in tropical or sub-tropical freshwaters where the probability of hypoxia is high. The aim of this study was to characterize by traditional histochemical and lectinhistochemical methods the pattern of carbohydrate in the intestinal mucosa. Intestine samples were taken from 25 healthy adult specimens collected in Buenos Aires (Argentina). Samples were fixed by immersion in 10 % buffered formalin and routinely processed and embedded in paraffin wax. Subsequently, these sections were incubated in the biotinylated lectins battery. Labeled Streptavidin-Biotin (LSAB) system was used for detection, diaminobenzidine as chromogen and haematoxylin as a contrast. To locate and distinguish glycoconjugates (GCs) of the globet cells, we used the following histochemical methods: PAS; PAS*S; KOH/ PA*S; PA/Bh/KOH/PAS; KOH/PA*/Bh/PAS; Alcian Blue and Toluidine Blue at different pHs. Microscopically, the general structure of vertebrate intestine was observed and showed all the cell types characteristic of the intestinal epithelium. The cranial sector of catfish intestine is a site of digestion and absorption and its structure is similar to other fish groups. In contrast, enterocytes of the caudal portion are low cuboidal cells; and between these, globet cells and capillaries are observed, these latter may reach the mucosal lumen. Underlying the epithelium, observed a well-developed lamina propria-submucosa made of connective tissue; this layer was highly vascularized and did not exhibit glands. According to histochemistry, the diverse GCs elaborated and secreted in the intestine are associated with specific functions in relation to their physiological significance, with special reference to their role in lubrication, buffering effect and prevention of proteolytic damage to the epithelium together with other biological processes, such as osmoregulation and ion exchange. The lectinhistochemical analysis of the intestinal mucosa reveals the presence of terminal residues of glucose, mannose and galactose. In conclusion, this study has shown that GCs synthesized in the intestine of C. paleatus exhibit a high level of histochemical complexity and that the lectin binding pattern of the intestinal mucosa is characteristic of each species and the variations are related with the multiple functions performed by the mucus in the digestive tract. The information generated here may be a relevant biological tool for comparing and analyzing the possible glycosidic changes in the intestinal mucus under different conditions, such as changes in diet or different pathological stages. Rev. Biol. Trop. 64 (1): 327-340. Epub 2016 March 01.

Distribution of goblet and endocrine cells in the intestine: A comparative study in Amazonian freshwater Tambaqui and hybrid catfish

“…Similar to Tambaqui, the GC distribution of four from the six fishes fall in line with other omnivorous species such as C. paleatus (Plaul et al, 2016), P. fulvidraco (Cao & Wang, 2009) P. antalyae (Çinar & Şenol, 2006), and P. mesopotamicus, of the same family of Tambaqui Serrasalmidae (da Cruz, Moretti, Nordi, Cyrino, & Machado-Neto, 2017), except for A. bimaculatus (Cardoso et al, 2015) and T. obscrus (Hur et al, 2016) that showed assorted distribution of GCs (Table 3).…”

“…Similar to Tambaqui, the GC distribution of four from the six fishes fall in line with other omnivorous species such as C . paleatus (Plaul et al, ), P . fulvidraco (Cao & Wang, ) P .…”

Scanning electron microscope investigation on the process of healing of skin wounds in Cirrhinus mrigala

“…Scale bar 5 5 mm 1 h in Labeo rohita (Rai et al, 2012). Accumulation of mucus in the wound gap soon after the infliction of wound is significant in the light of the reports that fish skin mucus is associated to play various important functions (Plaul, Barbeito, & Díaz, 2016;Shephard, 1994).…”

“…Accumulation of mucus in wound gap in 30 min to 2 h has also been reported in the incised wound in the skin of Rita rita (Mittal & Munshi, ); within 1 h in Labeo rohita (Rai et al, ). Accumulation of mucus in the wound gap soon after the infliction of wound is significant in the light of the reports that fish skin mucus is associated to play various important functions (Plaul, Barbeito, & Díaz, ; Shephard, ). Recently, Balasubramanian et al (), Nigam, Kumari, Mittal, and Mittal (), and Kumari, Nigam, Mittal, and Mittal () suggested that skin mucus play an important role in the protection of the fish against microbial invasion.…”

Histochemistry of the zona pellucida of the ovary of a species with natural polyovulation: Lagostomus maximus (Rodentia, Hystricomorpha, Chinchillidae)

“…Of each ovary, no less than 15 follicles in which the ZP was evident were observed; among them: preantral, secondary, tertiary, polyovulatory and atretic follicles. The intensities of the different techniques were classified according to the following semi‐quantitative scale: 0, unlabelled; 1, light mark; 2, moderate mark; and 3, strong mark, according to the criterion used in previous works (Barbeito, Ortega, Matiller, Gimeno, & Salvetti, ; Boonzaier, Merwe, Bennett, & Kotze, ; Liquori et al, ; Mastrodonato, Mentino, Liquori, & Ferri, ; Plaul, Barbeito, & Díaz, ), including some carried out in the species under study (Flamini et al, ; Tano de la Hoz, Flamini, & Díaz, ).…”