Histochemical detection of sugar residues in the chick embryo mesonephros with lectin-horseradish peroxidase conjugates

Glycobiology of developing chicken kidney: Profiling the galectin family and selected β-galactosides

The concept of the sugar code interprets the cellular glycophenotype as a rich source of information read by glycan-lectin recognition in situ. This study's aim is the comprehensive characterization of galectin expression by immunohistochemistry during chicken nephrogenesis along with mapping binding sites by (ga)lectin histochemistry. Light and two-color fluorescence microscopy were used. First, six plant/fungal lectins that are specific for galectin-binding parts of N- and O-glycans were applied. The spatiotemporally regulated distributions of these glycans in meso- and metanephros equip cells with potential binding partners for the galectins. Complete galectin profiling from HH Stage 20 (about 70-72 hr) onward revealed cell-, galectin-, and stage-dependent expression patterns. Representatives of all three types of modular architecture of the galectin family are detectable, and overlaps of signal distribution in light and two-color fluorescence microscopy illustrate a possibility for functional cooperation among them. Performing systematic galectin histochemistry facilitated comparisons between staining profiles of plant lectins and galectins. They revealed several cases for differences so that tissue lectins appear to be selective among the β-galactosides. Notably, selectivity is also disclosed in intrafamily comparison. Thus, combining experimental series with plant and tissue lectins is a means to characterize target populations of glycans presented by cellular glycoconjugates for individual galectins. Our results document the presence and sophisticated level of elaboration among β-galactosides and among the members of the family of galectins during organogenesis, using chicken galectins and kidney as model. Thus, they provide a clear guideline for functional assays using supramolecular tools, cells, and organ cultures.

Presence of sialic acid in prothoracic glands of Galleria mellonella (Lepidoptera)

The presence of sialic acid (SA) in prothoracic glands (PGs) of Galleria mellonella was determined by the methods of electron microscopy (EM), histochemistry, spectrophotometry (SP) and electronic ionization (EI)-mass spectroscopy. Histochemical observations were carried out by the cationic dye ruthenium red (RR), staining with and without neuraminidase digestion in the larval stage. Neuraminidase-sensitive SA was demonstrated by the decrease in the amount of RR-binding following neuraminidase digestion. The total amount of SA was found to be 0.09016 mg g(-1) in dry tissue by spectrophotometric determination. EI-mass spectroscopy results confirmed the EM and SP observations. The fragmentation scheme derived from EI-mass analysis exhibited the presence of the lactonized form of Neu5Gc7, 9Ac(2). On the basis of the various pieces of evidence described above, it was firmly concluded that Neu5Gc7, 9Ac(2) molecules were present in PGs of G. mellonella.

The histological observations on the large intestine of the goose (Anser anser) during the pre- and post-hatching periods

The development of the cecum and colon in the goose was investigated during the period from the 15th to 28th day of the incubation and from 1 to 30 days of age after hatching by light microscopy. By day 15 of the incubation, in the cecum and colon, the lumen was surrounded by pseudostratified epithelium. The previllous ridges appeared at 15th and 17th days of the incubation in the colon and ceca, respectively. At the base of previllous ridges, the epithelium changed into a simple prismathic epithelium at 15th and 17th days of the incubation in the colon and cecum, respectively. The villi appeared at the 21st days of the incubation. The crypts and goblet cells appeared on the first day after hatching. In the pre-hatching period, the lamina muscularis mucosa was present only in the colon. The submucosa consisted of loosely aggregated connective tissue in the pre-hatching period. In the post-hatching period, it consisted of a very thin layer of connective tissue. Its presence was only obvious where the cells of the submucosal nerve plexus or occasional large blood vessels considerably increased its thickness. The nerve plexus corresponding to the Auerbach's plexus of the mammalian intestine and submucosal nerve plexus appeared by 15th days of the incubation. From the 15th to 28th day of incubation, the tunica muscularis consisted of circular smooth muscle cells in the ceca. On the 28th day of the incubation a thinner longitudinal muscle layer added to the circular muscle layer. In the colon there was an outer longitudinal and a thicker circular muscle layer.

Temporal and spatial regulation of expression of two galectins during kidney development of the chicken

Organogenesis and the establishment of the mature phenotype require an interplay between diverse recognition systems. Concerning protein-carbohydrate interactions, galectins are known to be involved in several extra- and intracellular functions. Due to the occurrence of two avian galectins in liver (chicken galectin-16 CG-16) and intestine (chicken galectin-14; CG-14) with different developmental regulation. the questions addressed are to what extent and where these galectins are present during chicken kidney development. Using Western blot analysis, the presence of both activities in tissue extracts was ascertained. A solid-phase assay showed peak levels at day 12 followed by a decline. A histochemical analysis was carried out in combination with routine staining. Epithelial cells of the mesonephric proximal tubules were immunoreactive in the cytoplasm for CG-14 from day 5 of incubation onwards. Additionally, epithelial cells of the metanephric collecting ducts were stained. For CG-16 a rather similar pattern of staining was seen, additional positivity in early glomerular podocytes being notable. At the electron microscopical level, a diffuse staining for CG-14 was seen in the cytoplasm, whereas immunoreactivity for CG-16 was observed mainly in mitochondria. These results demonstrate quantitative differences in the developmental regulation of the two avian galectins with obvious similarities in the cell-type pattern but with a disparate intracellular localisation profile.

Glycoconjugate sugar residues in the chick embryo developing lung: a lectin histochemical study

A lectin histochemical study was performed to investigate the distribution and changes of the oligosaccharidic component of the glycoconjugates in the lung of chick embryos, of 1-day-old chick, and of the adult animal. For this purpose, a battery of seven horseradish peroxidase-conjugated lectins (PNA, SBA, DBA, WGA, Con A, LTA, and UEA I) were employed. During the first phase of parabronchi and atria formation, D-galactose-(beta1-->3)-N-acetyl-D-galactosamine, beta-N-acetyl-D-galactosamine, D-glucosamine, alpha-D-mannose, and sialic acid, present at the level of the surface and of cytoplasmic granules of the lining epithelial cells, seem to play a role in regulating morphogenetic phenomena. In the subsequent phases, the parabronchial lumen and the atrial cavities were characterized by the presence of lectin-reactive material rich in terminal D-galactose-(beta1-->3)-N-acetyl-D-galactosamine, beta-N-acetyl-D-galactosamine, D-glucosamine and alpha-D-mannose. From day 18 onwards and immediately after hatching, the free border of the cells lining the air capillaries was characterized by the presence of beta-N-acetyl-D-galactosamine and alpha-D-mannose. The appearance of these sugar residues was concomitant with the beginning of respiratory activity.

Glycoconjugate saccharidic moieties of the exocrine and endocrine pancreas in the chick embryo, newborn and adult

A battery of horseradish peroxidase-conjugated lectins (PNA, SBA, DBA, WGA, ConA, LTA and UEAI) was used to study the distribution of glycoconjugate sugar residues in the exocrine and endocrine pancreas of chick embryos, 1-day-old chicks and adult animals. During the period of incubation considered here, the time of appearance and changes in the oligosaccharides were noted in the acinar cells, in the endocrine cells of the "light islets" and in the capillary endothelial cells. In the developing exocrine pancreas, the basolateral surface of the acinar cells reacted with PNA, WGA, LTA and ConA for the entire period of incubation while SBA, WGA, LTA and ConA reactivity was detected in the apical plasma membrane. Zymogen granule membrane reacted with PNA, WGA and LTA from the 12th day onward, while ConA reactivity was detectable from the 7th day onward. Owing to its early appearance, alpha-D-mannose, revealed by ConA lectin, might in some way contribute to the maturation of the zymogen granule. In the 1-day-old chick and in the adult the cellular surface reacted with WGA and ConA. The zymogen granule membrane reacted with PNA, WGA and ConA in the 1-day-old chick. In the adult, WGA and ConA reactivity was observed in the zymogen granule membrane, whereas at this site PNA reactivity was revealed only after neuraminidase digestion. The hypothesis formulated by others that granule membrane lectin reactivity is equal to the apical membrane reactivity, owing to exocytotic processes, is not consistent with our results in the chick embryos, the 1-day-old chick and the adults. The surface and the granules of the islet beta cells in different periods of incubation reacted with WGA, SBA and, after neuraminidase treatment, with PNA. The same reactivity was seen also in 1-day-old chick while in the adult the granules of the beta cells also reacted with ConA. These findings show the achievement of an almost adult-like state of glycosylation of the glycoconjugates in the beta cells at an early stages of development.

Changes in expression of the oligosaccharides in the human fetal skin

Lectin histochemistry was used to investigate the glycoconjugate saccharidic moieties in the skin of human fetuses ranging in age from the 8th to the 13th week of gestation. For this purpose, seven HRP-conjugated lectins were employed (Con A, WGA, PNA, DBA, SBA, UEAI and LTA). The distribution and changes of the sugar residues of glycoconjugates at the level of the various layers of the fetal epidermis, as well of the underlying mesenchyme were studied. We have shown that UEAI reactivity is a characteristic finding of the cells of the intermediate layer at the 11th and 12th week of gestation. LTA reactivity was detected only at the free border of the peridermal cells from the 10th to the 13th week of gestation. We demonstrated the presence of PNA binding sites at both the basal and peridermal cells from the 8th week of gestation, whereas other authors have stated that the appearance of PNA reactivity coincides with the onset of fetal skin stratification (11th-12th week of gestation). Moreover, some typical features in lectin reactivity at the level of the mesenchymal cells and fibres have been pointed out.

Glycoconjugate expression in the chick embryonic chorioallantoic membrane: comparisons of the chorionic ectoderm and allantoic endoderm

BACKGROUND

The chorioallantoic membrane (CAM) of the chick embryo expands during embryogenesis to meet the increased oxygen demands during growth and differentiation. Temporal and spatial glycosylation patterns of CAM ectodermal and endodermal proteins likely contribute to differentiation of the functional attributes of the CAM.

METHODS

Using lectins for light and electron microscopic observations, we studied the patterns of glycoconjugate expression on the ectoderm and endoderm of the chorioallantoic membrane (CAM) of the chick at days 4.5, 5.0, 5.5, 6.0, and 10 of morphogenesis. For light microscopy, samples of unfixed CAM were incubated with the following FITC lectins: Con A, DBA, GSA-I, GSA-II, PNA, SBA, UEA-I, and WGA.

RESULTS

All lectins, except GSA-I and -II, gave positive results. The positive lectins, labeled with HRP, served to ultrastructurally localize PNA, SBA, and WGA, but not DBA binding to the luminal surface of the endoderm. UEA-I and Con A bound similarly except on day 10 when UEA-I no longer bound. On the ectodermal surface, only WGA bound at all times studied. PNA and SBA binding were present from days 5.0 to 6.0 but absent at days 4.5 and 10. DBA binding occurred through day 5.0 but was absent thereafter. UEA-I bound to the ectoderm at days 4.5, 5.0, and 10 but not days 5.5 and 6.0. Con A bound only on days 5.0 and 10.

CONCLUSION

That the ultrastructurally similar ectoderm and endoderm of the CAM display functional differences conforms to the hypothesis that differential expression of glycoconjugate microdomains likely contributes to such functional specialization.

Identification of sugar residues in secretory glycoconjugates of the lining and glandular epithelium of the chick embryo gizzard using lectin histochemistry

Using seven horseradish peroxidase-conjugated lectins we studied the distribution of glycoconjugate sugar residues in the lining and glandular epithelium of the gizzard in chick embryos from day 7 to 21 of incubation. At the outer layer of the lining epithelium all investigated sugar residues were present from day 7 onwards, except alpha-L-fucose, which was detected later. From day 9 some cells, which contained granules characterised by D-galactose-(beta 1--->3)-N-acetyl-D-galactosamine and N-acetyl-D-glucosamine, were observed in the inner part of the lining epithelium. Afterwards, although in different time periods, all investigated oligosaccharides were detected in intercellular spaces filled with mucous material. At first, the cells of the anlage of the tubular glands appeared to be characterised by D-glucosamine and alpha-D-mannose only. Afterwards, all the investigated sugar residues were detected. At hatching, the luminal glandular secretion showed all investigated sugar residues, except alpha-L-fucose, which was typical for the early formation of the tubular glands. Our data suggest that during the development of the gizzard three time periods of mucous release can be distinguished.

Chick embryo metanephros: the glycosylation pattern as revealed with lectin conjugates

Fragments of metanephros were taken from chick embryos and studied from the 7th to the 21st d of incubation. A battery of 7 different horseradish peroxidase-labelled lectins (PNA, ConA, DBA, SBA, LTA, WGA and UEA I) was used to analyse the distribution and changes of carbohydrate moieties in glycoconjugates along the metanephric nephron from the S-shaped body stage onwards. DBA and SBA reacted for a short time at some sites during the considered period of incubation. Provided WGA and ConA reacted with most of the nephric components, the almost ubiquitous presence of N-acetyl-D-glucosamine and alpha-D-mannose was demonstrated. SBA and LTA were found to be good markers of the proximal tubule. On the 12th d of incubation, sialic acid was found in the podocytes, capillary walls, and the connecting and collecting ducts. On the same day, other oligosaccharides were present at the nephric tubular components. The simultaneous presence of sialic acid and other sugar residues may be significant for the identification of the exact stage of incubation at which metanephric activity starts. The possible role of some sugar residues for the regulation of metanephric activity is discussed.

Immunohistochemical localization of transforming growth factor-alpha and epidermal growth factor-receptor in the mesonephros and metanephros of the chicken

Transforming growth factor-alpha (TGF-alpha) is a polypeptide related to epidermal growth factor (EGF). Both bind to EGF-receptor (EGF-R) to carry out their function in a variety of tissues and cell lines. Several studies have shown their presence in mammalian kidney, however, nothing has to date been stated concerning their existence in avian kidney. Expression of TGF-alpha and EGF-R is reported here for the first time during the development of the chicken kidney. Using immunohistochemical techniques, we identified a TGF-alpha (but not EGF) in mesonephric distal tubule cells from day 8 to day 20 of embryonic development and in metanephric distal tubule cells from day 14 of embryonic development to the adult. The histochemical characteristics of these cells and their histological localization suggest that they may be the "principal cells" of the distal tubules. Similarly, EGF-R was found in mesonephric proximal tubule cells from day 7 to day 18 of embryonic development and in metanephric proximal tubule cells from day 13 of embryonic development up to adult stages. The coexistence of both TGF-alpha and EGF-R from the onset of development of mesonephros and metanephros supports their possible role in mechanisms of proliferation and differentiation of the cells of these organs.

Histochemical detection of sugar residues in chick embryo developing lingual glands with horseradish-peroxidase conjugated lectins

Tongue anlage were taken in chick embryos from the 7th to the 21st d of incubation and in 3 d old chicken. A battery of 7 different horseradish peroxidase-conjugated lectins (PNA, ConA, DBA, SBA, LTA, WGA, UEA I) was used to study the carbohydrate residues of glycoconjugates at the epithelial cells of the anterior and posterior lingual glands. Some sugar residues, detected at the surface of the epithelial cells in early developmental stages of glandular primordia, seemed to play a role in inducing and regulating the first differentiative steps of the glands. Differences in type, amount, time of appearance and cellular localization between the 2 groups of glands were detected. The group of the anterior lingual glands, adjacent to the entoglossal cartilage (paraentoglossal glands), showed some peculiar histochemical characteristics.