Expression of polysialic acid, alpha- and beta-cantenins in adult toad testis in hibernation stage and after gonadotrophin--releasing hormone (GnRH) treatment.

The Polysialic Acid (PSA), glycosydic moiety of the Neural Cell Adhesion Molecule (N-CAM), and alpha- and beta-Catenins, which mediate interaction between Cadherins and cytoskeletal proteins, participate in cell adhesion phenomena in numerous organs and tissues. We have performed an immunohistochemical analysis, in hibernating toad testis and in GnRH-reactivated hibernating animals. In hibernating toads we could demonstrate PSA-immunoreactivity (PSA-IR) within the seminiferous tubules, in clusters of primary spermatocytes, spermatids and spermatozoa, in follicular and Sertoli cells. PSA-IR was seen in peritubular, Leydig and efferent duct cells. In GnRH-treated toads PSA-IR persists in primary spermatocyte groups. alpha-Catenin is localized in the basal laminae of seminiferous tubules and in Leydig cells of hibernating toads. This did not change after hormonal treatment. In hibernating toads, beta-Catenin was detected only in Leydig cells and within seminiferous tubules on basal spermatocystes and limiting spermatozoa clusters. In GnRH-treated toads, the beta-Catenin-IR was less intense in Leydig cells and vanished within seminiferous tubules.

Expression of isoforms of the neural cell adhesion molecule (NCAM) and polysialic acid during the development of the Bufo arenarum olfactory system.

The neural cell adhesion molecule (NCAM), a member of the immunoglobulin superfamily that promotes Ca(2+)-independent cell-cell adhesion, is expressed as various isoforms generated by alternative splicing. In this study, the expression of the 180 kDa isoform (180-NCAM), total NCAM (180, 140 and 120 kDa isoforms) and the polysialic acid moiety of NCAM (PSA) were analyzed during the development of the olfactory system of the toad Bufo arenarum using specific antibodies and immunofluorescence light microscopy. NCAM and PSA were not found in the ectodermal thickening corresponding to the olfactory placode at early larval stage (stage 17), but by stage 19, total NCAM, 180-NCAM and PSA were all expressed in the invaginating olfactory placode at the sites of cell-cell contact and in the differentiating olfactory epithelium. Later, NCAM isoforms and PSA were found also in the primary fibers of the olfactory nerve and in the olfactory bulb. However, the expression of 180-NCAM decreased near the end of larval development and was absent in post-metamorphic and adult animals. In contrast, total NCAM (representing 140 and/or 120 kDa isoforms) and PSA continued to be expressed in olfactory tissues of post-metamorphic and adult animals, consistent with the persistent neural plasticity of this tissue. Because 180-NCAM has been associated with non-proliferating neurons, its down-regulation in post-metamorphic and adult olfactory system may be associated with the regenerative capability and continuous cell turnover documented for this region in adult animals.

Estrogen influence on maturational pathway of murine mammary tumor virus: an immunoelectron microscopy study.

Modifications induced by estrogens on hormone-independent murine mammary tumor (MMT) and its main etiological agent, the MMT virus (MMTV), are reported. High doses of estrogens released continuously from silastic capsules delay significantly the development of transplanted tumors into syngeneic hosts. Neoplastic cells present a striking cytoplasmic vacuolization and changes in the MMTV differentiation pattern. Mature virions are detected budding into cytoplasmic vacuoles instead of the extracellular space as in spontaneous and untreated transplanted tumors. This phenomenon is reversed after estrogen withdrawal at the first sign of tumor development. Application of electron microscope immunocytochemistry with colloidal gold-protein A complex and multiple monospecific antibodies reveals several interesting features. In spontaneous and untreated tumor grafts, structural viral proteins p14 and p25 appear in both intracytoplasmic capsids and mature extracellular viruses. By contrast glycoprotein gp55 labels only the envelope of mature virus. In estrogen-treated tumors this antigenic pattern is modified and the gp55 is detected in those atypical virions maturing into the intracytoplasmic vacuoles. These observations led to the conclusions that the delay in the development of hormone-independent mammary tumors caused by estrogen is due to an abnormal maturational viral process and that estrogens induce alterations of polarity in the translocation process of viral envelope glycoproteins.

Immunocytochemical detection of estrogen receptors in a hormone-unresponsive mammary tumor.

A combination of two monoclonal antibodies and high resolution immunocytochemical technique was applied to label estrogen receptors in spontaneous mouse mammary tumors. Protein A-colloidal gold complex was used as an electron opaque marker. With this procedure estrogen receptors were labelled in the nuclei of cancer cells, predominantly over heterochromatin. In the cytoplasm a slight tagging of the rough endoplasmic reticulum was detected, apparently related with the sites of receptor biosynthesis. Other organelles and the mammary tumor viruses (MuMTV) were not stained immunocytochemically. The immunocytochemical procedure applied in this investigation allowed the detection of low levels of estrogen receptors in an estrogen-unresponsive mammary carcinoma. The presence of estrogen receptors with a specific distribution in estrogen-independent tumors suggests the need of a reevaluation of their capacity as indicators of hormone-dependence in mammary carcinomas.

Differential detection of murine mammary tumor virus constituents by immuno-electron microscopy

Diferentes antigenos del virus productor de tumores mamarios del raton (MMTV) fueron detectados con la aplicación de varios anticuerpos poli monoespecíficos y una técnica inmunocitoquímica de alta resolución con oro coloidal. Anticuerpos preparados contra el virus total aislado (partículas B), las proteínas p14, p25 y una glicoproteína gp55 fueron marcados con el complejo oro coloidal proteína A en secciones de carcinomas mamarios espontáneos del raton, incluidos en resina acrílica (L. R. Whrite, London Resin Company). La estructura proteica de las nucleocapsides y la envoltura viral fueron los componentes más inmunoreactivos de la subestrutura del virus MMTV. Una continuidad de los constituyentes antigénicos del virus fueron encontrados en las diferentes etapas de la morfogénesis del virus demonstrándose una correlación entre estructuras precursoras y el virus infeccioso

Differential detection of murine mammary tumor virus constituents by immuno-electron microscopy

Diferentes antigenos del virus productor de tumores mamarios del raton (MMTV) fueron detectados con la aplicación de varios anticuerpos poli monoespecíficos y una técnica inmunocitoquímica de alta resolución con oro coloidal. Anticuerpos preparados contra el virus total aislado (partículas B), las proteínas p14, p25 y una glicoproteína gp55 fueron marcados con el complejo oro coloidal proteína A en secciones de carcinomas mamarios espontáneos del raton, incluidos en resina acrílica (L. R. Whrite, London Resin Company). La estructura proteica de las nucleocapsides y la envoltura viral fueron los componentes más inmunoreactivos de la subestrutura del virus MMTV. Una continuidad de los constituyentes antigénicos del virus fueron encontrados en las diferentes etapas de la morfogénesis del virus demonstrándose una correlación entre estructuras precursoras y el virus infeccioso (AU)