Binding of fluorescein isothiocyanate conjugated lectins to rat spermatogenic cells in tissue sections: Enhancement of lectin fluorescence obtained by fixation in Bouin's fluid

Identification of a variant-specific phosphorylation of TH2A during spermiogenesis

Tissue-specific histone variant incorporation into chromatin plays dynamic and important roles in tissue development. Testis is one such tissue, and a number of testis-specific histone variants are expressed that have unique roles. While it is expected that such variants acquire post-transcriptional modifications to be functional, identification of variant-specific histone modifications is challenging because of the high similarity of amino acid sequences between canonical and variant versions. Here we identified a novel phosphorylation on TH2A, a germ cell-specific histone H2A variant. TH2A-Thr127 is unique to the variant and phosphorylated concomitant with chromatin condensation including spermiogenesis and early embryonic mitosis. In sperm chromatin, phosphorylated TH2A-Thr127 (=pTH2A) is co-localized with H3.3 at transcriptional starting sites of the genome, and subsequently becomes absent from the paternal genome upon fertilization. Notably, pTH2A is recurrent and accumulated in the pericentromeric heterochromatin of both paternal and maternal chromosomes in the first mitosis of embryos, suggesting its unique regulation during spermiogenesis and early embryogenesis.

Distribution of lectin-bindings in the testis of the lesser mouse deer, Tragulus javanicus

The distribution of lectin bindings in the testis of the smallest ruminant, lesser mouse deer (Tragulus javanicus), was studied using 12 biotinylated lectins specific for d-galactose (peanut agglutinin PNA, Ricinus communis agglutinin RCA I), N-acetyl-d-galactosamine (Dolichos biflorus agglutinin DBA, Vicia villosa agglutinin VVA, Soybean agglutinin SBA), N-acetyl-D-glucosamine and sialic acid (wheat germ agglutinin WGA, s-WGA), D-mannose and d-glucose (Lens culinaris agglutinin LCA, Pisum sativum agglutinin PSA, Concanavalin A Con A), L-fucose (Ulex europaeus agglutinin UEA I), and oligosaccharide (Phaseolus vulgaris agglutinin PHA-E) sugar residues. In Golgi-, cap-, and acrosome-phase spermatids, lectin-bindings were found in the acrosome (PNA, RCA I, VVA, SBA, WGA and s-WGA), and in the cytoplasm (PNA, RCA I, VVA, SBA, WGA, LCA, PSA, Con A and PHA-E). s-WGA binding was confined to the spermatid acrosome, but other lectins were also observed in spermatocytes. In spermatogonia, VVA, WGA, Con A, and PHA-E bindings were observed. Sertoli cells were intensely stained with DBA and Con A, and weakly with PHA-E. In interstitial Leydig cells, RCA I, DBA, VVA, Con A, PSA, LCA, WGA and PHA-E were positive. UEA I was negative in all cell types including spermatogenic cells. Unusual distribution of lectin-bindings noted in the testis of lesser mouse deer included the limited distribution of s-WGA only in the spermatid acrosome, the distribution of DBA in Sertoli cells, Leydig cells and lamina propria, and the absence of UEA I in all type cells. The present results were discussed in comparison with those of other animals and their possible functional implications.

A Lectin Histochemical Study on the Testis of the Babirusa, Babyroussa babyrussa (Suidae)

The distribution of lectin bindings in the testis of babirusa, Babyrousa babyrussa (Suidae) was studied histochemically using 10 biotinylated lectins, Peanut agglutinin (PNA), Ricinus communis agglutinin (RCA I), Dolichos biflorus agglutinin (DBA), Vicia villosa agglutinin (VVA), Soybean agglutinin (SBA), Wheat germ agglutinin (WGA), Lens culinaris agglutinin (LCA), Pisum sativum agglutinin (PSA), Concanavalin A(Con A) and Ulex europaeus agglutinin (UEA I). Nine of 10 lectins showed a variety of staining patterns in the seminiferous epithelium and interstitial cells. The acrosome of Golgi-, cap- and acrosome-phase spermatids displayed various PNA, RCA I, VVA, SBA and WGA bindings, indicating the presence of glycoconjugates with D-galactose, N-acetyl-D-galactosamine and N-acetyl-D-glucosamine sugar residues respectively. No affinity was detected in the acrosome of late spermatids. LCA, PSA and Con A which have affinity for D-mannose and D-glucose sugar residues were positive in the cytoplasm of spermatids and spermatocytes. DBA was positive only in spermatogonia. In addition to DBA, positive binding in spermatogonia was found for VVA, WGA and Con A, suggesting the distribution of glycoconjugates with N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, D-mannose and D-glucose sugar residues. Sertoli cells were stained intensely with RCA I, WGA and Con A. In Leydig cells, RCA I and Con A were strongly positive, while WGA, LCA and PSA reactions were weak to moderate. The present findings showed that the distribution pattern of lectin binding in the testis of babirusa is somewhat different from that of pig or other mammals reported previously.

Histochemical study of glycoconjugates in active and photoperiodically-regressed testis of hamster (Mesocricetus auratus)

The objective of the present study was to characterize glycoconjugates of hamster testis in gonadally-active and -inactive states by lectin histochemical methods. Thirteen HRP- or digoxigenin-labeled lectins were used in samples obtained from fertile and photoinhibited hamsters. In gonadally-active hamsters, spermatozoa tails were stained with Con-A, HPA, PNA, UEA-I, LTA, AAA, WGA and LFA and weakly with GNA and RCA-I. Spermatozoa acrosomes were labeled with HPA, SBA, WGA and PNA. Spermatid acrosomes were labeled with SBA, RCA-I, PNA, and WGA. Staining with GNA and Con-A was found in the Golgi phase and HPA staining was found in the Golgi phase and maturated spermatids. Cytoplasm of spermatocytes was labeled with Con-A, GNA, LTA, AAA, RCA-I, HPA, WGA and LFA, whereas spermatocyte membranes were stained with Con-A, LTA and AAA. Spermatogonia were strongly labeled with Con-A and moderately labeled with AAA, WGA and LFA. Sertoli cells were positive after staining with Con-A, AAA, WGA, and LFA. The lamina propria was positive after staining with UEA-I, LTA, AAA and LFA. Leydig cells showed strong labeling with SBA, Con-A, GNA, SNA and MAA, moderate labeling with WGA, weak labeling with RCA-I, AAA and LFA. In gonadally-inactive hamsters, spermatocytes showed increased staining with HPA, PNA and AAA, whereas staining with Con-A, GNA and LTA had disappeared. Spermatogonia showed an increased labeling with AAA and WGA, but labeling with Con-A and LFA had disappeared. Sertoli cells were strongly labeled with GNA. Con-A and GNA staining was decreased in Leydig cells of gonadally-inactive hamsters but PNA and HPA staining was increased. The lamina propria in regressed testes showed intense labeling with PNA. These results suggest that histological, morphological and hormonal changes occurring in hamster testis during exposure to a short photoperiod are reflected in altered patterns of expression and distribution of N- and O-linked glycans.

Distribution of terminal sugar residues in the testis of the spotted rayTorpedo marmorata

Lectins represent a class of proteins/glycoproteins binding specifically to terminal sugar residues. The present investigation aims to identify lectin-binding sites in testis of Torpedo marmorata. Using a panel of lectins coupled with fluoresceine isothiocyanate, we demonstrated that germ and somatic cells present in Torpedo testis contain glycoconjugates, whose distribution at the level of the surface, the cytoplasm and the nucleus changes during germ cell differentiation. Moreover our observations demonstrate that the germ cells undergoing apoptosis (Prisco et al., 2003a: Mol Reprod Dev 64:341-348) overexpress a residual sugar recognised by WFA lectin that can be considered a specific marker for apoptotic germ cells. Finally, our results indicate that there is a progressive increase in glycosilation during spermatogenesis, especially at the level of the acrosome in the spermatocyte-spermatid step, and that Leydig cells are differently stained in relation to the spermatogenetic cycle.

Glycan residues of N- and O-linked oligosaccharides in the premeiotic spermatogenetic cells of the urodele amphibian Pleurodeles waltl characterize by means of lectin histochemistry

The aim of this work was the characterization of the glycoconjugates of the premeiotic spermatogenetic cells of the testis of an urodele amphibian, Pleurodeles waltl, by means of lectins in combination with several chemical and enzymatic procedures, in order to establish the distribution of N- and O-linked oligosaccharides in these cells. In the cytoplasm of the primordial germ cells, primary and secondary spermatogonia and primary spermatocytes, a granular structure can be observed close to the nucleus. These granules contain four types of sugar chains according to their appearance during the differentiation process: 1. some oligosaccharides that are identified in all the four cell types above mentioned, which include N-linked oligosaccharides with Fuc, Gal beta1,4GlcNAc and Neu5Ac alpha2,3Gal beta1,4GlcNAc and O-linked oligosaccharides with Gal beta1,4GlcNAc and Neu5Ac alpha2,3Gal beta1,4GlcNAc; 2. other glycan chains that are not present in the primary spermatocytes (N-linked oligosaccharides with DBA-positive GalNAc, GlcNAc, and a slight amount of Neu5Ac alpha2,6Gal/GalNAc and O-linked oligosaccharides with WGA-positive GlcNAc); 3. the sugar chains that are not in the earliest step of spermatogenesis (formed by both N-linked and O-linked oligosaccharides with Glc); and 4. other that appear at the earliest and latest stages, but not in the intermediate ones, (N-linked oligosaccharides with Man and O-linked oligosaccharides with SBA- and HPA-positive GalNAc and PNA-positive Gal beta1,3GalNAc). This structure could be related with the Drosophila spectrosome and fusome, unusual cytoplasmic organelles implicated in cystic germ cell development. Data from the present work, as compared with those from mammals and other vertebrates, suggest that, although no dramatic changes in the glycosylation pattern are observed, some cell glycoconjugates are modified in a predetermined way during the early steps of the spermatogenetic differentiation process.

Correlation between lectin binding and clinical factors in seminoma patients

The binding of a panel of lectins to histological sections of seminomas was studied. The findings were correlated with different clinical parameters. Concanavalin A and wheat germ agglutinin stained all seminomas whereas horse gram (DBA) and peanut agglutinin did not stain the tumor cells. A varying staining pattern was found with lectins from castor bean (RCA I), soy bean (SBA) and gorse (UEA I) indicating a heterogeneity of the tumor cell population. In the seminomas that were derived from undescended testis there were more cases that showed positive staining with soy bean agglutinin, which shows that the intra-abdominal location of the seminoma might cause changes in the cellular metabolism resulting in glycoconjugates different from those in descended tumors. No correlation was found between the lectin staining and the prognosis, stage or metastasis of the tumor.

Lectin binding to rat spermatogenic cells: effects of different fixation methods and proteolytic enzyme treatment

The binding of a panel of eight different fluorescein-conjugated lectins to rat spermatogenic cells was investigated. Particular attention was paid to the effects of different fixation methods and proteolytic enzyme digestion on the staining pattern. Concanavalin A (Con A), wheatgerm agglutinin (WGA), succinylated WGA (s-WGA) and agglutinin from gorse (UEA I) stained the cytoplasm of most germ cells as well as the spermatid acrosome. In contrast, peanut agglutinin (PNA), castor bean agglutinin (RCAI) and soy bean agglutinin (SBA) mainly stained the acrosome. The staining pattern varied depending on the fixation method used. PNA was particularly sensitive to formalin fixation, while SBA, DBA and UEA I showed decreased binding and Con A, WGA, s-WGA and RCA I were insensitive to this type of fixation. Pepsin treatment of the sections before lectin staining caused marked changes in the staining pattern; staining with PNA in formalin-fixed tissue sections was particularly improved but there was also enhanced staining with SBA and horse gram agglutinin (DBA). On the other hand, in Bouin- and particularly in acetone-fixed tissue sections, pepsin treatment decreased the staining with several of the lectins, for example WGA and UEA I.

Lectin binding to serous ovarian tumours

Sections of normal ovarian surface epithelium, benign serous cystadenomas, borderline serous cystadenomas and serous cyst-adenocarcinomas were stained with a pattern of lectins (Con A, WGA, SBA, DBA, UEA I, PNA and RCA I) to determine the different glycoproteins and their cellular changes. The epithelial cells stained with Con A, WGA, UEA I and RCA, although the intensity of the staining was generally higher in the malignant tumours. PNA stained only the malignant cells of the cystadenocarcinoma and DBA only the benign epithelial cells. These findings show that ovarian epithelial cells contain different glycoconjugates and that malignant transformation is accompanied by changes in the composition of these glycoconjugates.

Lectin binding to the human retina

Formalin-fixed, paraffin-embedded tissue sections of the human retina were stained with different fluorescein isothiocyanate-conjugated lectins. The lectins used were concanavalin A (Con A), Triticum vulgaris (WGA), glycine maximum (SBA), Dolichos biflorus (DBA), Ulex europaeus (UEA I), Arachis hypogaea (PNA), and Ricinus communis (RCA I). Con A stained both the inner and outer segments of the rods and cones, whereas WGA stained the inner and outer segments of the rods and the outer segments of the cones. PNA selectively stained only the inner segments of the cones. In addition, Con A and WGA stained neuron cytoplasm and nerve fibers in different layers of the retina. The results obtained differ in some important aspects from those previously obtained in the frog and monkey retina; this finding may be due to species differences. The results of lectin staining in the normal human retina may form the basis for future studies of retinal diseases.

Analysis of differentiation and transformation of cells by lectins

During differentiation cells are known to change their biological behavior according to their genotype. This is thought to be accompanied by a modulation of cell surface determinants expressed on the outer cell membrane. Vice versa, cell surface molecules are suggested to mediate extracellular signals to the genome. Most of these molecules integrated in the cell membrane have been proven to be glycoconjugates. The carbohydrate moieties of these molecules can be detected by means of lectins that are characterized by their ability to react specifically with distinct terminal sugar sequences. Thus, lectins have been used as appropriate tools for studying the modulation of functionally important membrane-associated molecules during the differentiation of cells, in particular of B- and T-lymphocytes. Moreover, lectins have been proven to distinguish between differentiated cells and malignant cell clones, according to the hypothesis that transformed cells possess a glycoconjugate profile that corresponds to the stage of differentiation at which they are arrested. Since lectins, like monoclonal antibodies, make it possible to study functionally important molecules that are associated with differentiation and malignancy, they might be of value for diagnostic purposes and, moreover, for analyzing malignant transformation.

Lectin binding to prostatic adenocarcinoma

The binding of different lectins (concanavalin A [Con A], triticum vulgaris [WGA], glycine maximum [SBA], dolichos bilflorus [DBA], ulex europaeus [UEA I], arachis hypogaea [PNA], and ricinus communis [RCA I]) to cells of normal prostate glands, hyperplastic glands and adenocarcinoma was studied. The Con A, WGA, DBA, PNA and RCA I bound to both normal and hyperplastic glands. The binding in the malignant glands differed from that of the benign conditions. The SBA, which was not bound by benign cells, was bound to the malignant glandular cells. Also, UEA I was bound to a part of the carcinoma cells. In addition, the binding pattern of Con A and WGA in the cells differed between the malignant and benign conditions. Based on the results of this study, it is suggested that lectin histochemical study might be useful in routine pathologic examination to detect malignant cells in cases which are doubtful with regard to malignancy by routine methods.

Distribution of glycoconjugates in human testis. A histochemical study using fluorescein- and rhodamine-conjugated lectins

Differentiation in the seminiferous epithelium involves the orderly transformation of germ cells into spermatozoa. We have employed ten fluorescein- and rhodamine-labeled lectins to visualize distinctive changes in the distribution of carbohydrate containing compounds during spermatogenesis and noticed the increase in RCA I, PNA, SBA and HPA binding sites during germ cell differentiation, suggesting the appearance of certain galactose and N-acetylgalactosamine containing glycoconjugates. Besides, in the cytoplasm of all germ cell types the positive reactions with Con A, LCA, WGA, LPA and UEA I indicate the presence of mannose, N-acetylglucosamine, sialic acid and fucose containing glycosubstances. Developing acrosomes demonstrated binding sites for most lectins, and particular HPA binding glycoconjugates were expressed in the equatorial segment region of late spermatids and testicular spermatozoa. In addition, the characteristic staining patterns of other testicular compartments are described. Our results suggest that human germ cells are rich in various carbohydrate containing compounds and there are specific alterations in cellular glycoconjugates during germ cell differentiation.

Lectin binding sites in human seminiferous epithelium, in CIS cells and in seminomas

The distribution of glycoconjugates in germ cells during spermatogenic differentiation, in carcinoma-in-situ (CIS) cells and in seminoma were studied by lectin histochemistry. The results show that human germ cells are rich in carbohydrate-containing compounds with specific alterations in the expression of glucosyl moieties during germ cell development. CIS cells reveal different lectin binding sites from spermatogenic cells, but the distribution of glycosubstances in CIS cells is similar to that of seminoma cells which supports the suggestion of the malignant nature of CIS germ cells.

Lectin binding to collagen strands in histologic tissue sections

Histologic sections from human skin and uterine ligaments were stained with the following FITC conjugated lectins: Con A, WGA, s-WGA, SBA, DBA, UEA I, PNA, RCA I, BPA, GSA I, GSA II, MPA and LPA. The staining of the connective tissue was similar in the dermis and the uterine ligaments and it was most intense in the extracellular matrix containing collagen strands whereas the fibrocytes remained unstained. The staining was clear with glucose or N-acetylglucosamine binding lectins like Con A, WGA, s-WGA and GSA II, which may be related to the presence of glucose residues in collagenous hydroxylysine. The staining with some of the galactose or N-acetylgalactosamine binding lectins like RCA I, DBA, and BPA was less intense. This may reflect the presence of terminal galactose sugars in the hydroxylysine of collagen. No staining was found with SBA, UEA I, PNA, GSAI, MPA or LPA. The results show that different particularly glucose specific lectins bind to the extracellular matrix and especially to collagenous strands in connective tissue. It is suggested that this might be used in histochemical studies of connective tissue and particularly concerning the changes that may occur in different disease states.

Lectin-binding pattern of bull testis and epididymis

Seven rhodamine-conjugated lectins (PNA, RCA I, SBA, Con A, WGA, UEA I, DBA) were used to study the distribution of glycoproteins in the testis and epididymis of immature, juvenile, and adult bulls. A marked change was found in the staining pattern of the lectins in the seminiferous tubules during acrosomal development, and the Sertoli cells seemed to have a cyclic affinity for some of the lectins. The distribution of lectin staining in six regions of the bull epididymis showed some typical differences that were associated with the secretory and absorptive functions of the organ. Region 1 was characterized by strong surface and villous staining and a patchy reaction in the principal cells. Regions 2 and 3 showed a strongly reactive apical Golgi zone and secretory material. In regions 4 and 5, the Golgi zone was subapical but strongly reactive with most lectins, while in region 6 a weakly reactive apical Golgi zone was found. During sexual maturation, an increasing number of basal cells with a strong affinity for some lectins was found at the periphery of the epithelium in regions 2 to 6. These regions also had lectin-stained material along the basal border of the principal cells. These findings suggest that the basal cells may be active in the digestion of absorbed material and that they derive from the principal cells, which may be active in transporting absorbed material to them. The staining pattern of the spermatozoa changed during their transit through the epididymis. The degenerating cells in the testis and epididymal tubules also showed an altered affinity for the lectins.