Combined UV and Liquid Scintillation Detection in HPLC. Formation and Depurination of Substitution Inert Pt(II) Complexes of Purine Nucleosides

Abstract

Combined UV- and liquid scintillation-HPLC has been applied to study the complexing of purine nucleosides with Pt(II)-diamine ions, and the effect of the complex formation on the acidic depurination.     

Basement membrane and epithelial features of fetal-type Leydig cells in rat and human testis

The basement membranes of developing Leydig cells in fetal and newborn testis of rat were studied by ultrastructural and immunocytochemical methods. Fetal-type Leydig cells in prenatal rats were organized in irregularly outlined groups in the interstitium and were extensively surrounded by ultrastructurally identifiable basement membranes and immunocytochemically localized laminin and collagen type IV. Prenatal Leydig cell precursors had small patches of laminin and collagen type IV on their surfaces, which indicated that changes in extracellular matrix took place during their differentiation to mature fetal-type Leydig cells. Additionally, ultrastructural evidence was obtained for a basement membrane surrounding the fetal human Leydig cells similar to that in fetal rats. Soon after birth the rat fetal-type cells gathered into distinct clusters surrounded by delicate envelope cells and a discontinuous basement membrane. Basement-membrane structures, laminin, and collagen type IV were observed between the clustered cells as well. The basement membranes covering large cell surface areas of the fetal-type Leydig cells in fetal and newborn rats differed from those of the adult-type cells, which, according to our earlier study, are covered only by small patches of basement membrane. The difference between the basement membranes of the fetal- and adult-type rat Leydig cells further supports the concept of two different Leydig cell populations. The earlier findings of the epithelial nature of the Leydig cells agree with the observation of basement membranes in the Leydig cells.     

The effect of progesterone on the localization of progesterone receptors in the nuclei of chick oviduct cells

Summary The location of occupied and unoccupied progesterone receptors (PR) in chick oviduct cells was studied by immuno-electron microscopy with the use of a highly specific polyclonal anti-PR antibody and pre-embedding modifications of the peroxidase-anti-peroxidase-(PAP-) or immunogold-silver methods. Both methods revealed a nuclear localization of the PRs. The location of the PR in the nucleus was studied in detail by means of the immunogold-silver method. The most intense labelling for unoccupied PRs was in the condensed chromatin. After occupation of PRs with progesterone (P), decondensation or dispersion of chromatin was observed. At the same time, the labelling in the border area of condensed and dispersed chromatin, and in the dispersed chromatin, increased. The changes were statistically significant. The results can be explained by conformational changes of the PR-containing chromatin rather than by translocation of PRs from one site to another.     

Intermediate filament proteins and epithelial differentiation in the embryonic ovary of the rat

Abstract. The development and sexual differentiation of gonads in female rat embryos and fetuses between the ages of 11 and 17 days was studied by immunocytochemical analysis of intermediate filament proteins and laminin by light and electron microscopy. In the 11-day-old pregonadal embryo, the surface epithelial cells in the ventral cortex of the mesonephros contained desmin but not cytokeratin or vimentin. The development of the gonad began on the following day by proliferative growth of the mesonephric surface cells, which like the subepithelial cells soon expressed vimentin in addition to desmin. The differentiation continued by formation of separate epithelial cell clusters, which joined into cords, irregular in shape and size. Desmin disappeared from the cord cells and cytokeratins appeared while vimentin remained in all somatic cell types. Desmin was especially abundant in some stromal cells adjacent to the epithelial tissues. After the segration of the basic ovarian tissues, vimentin and desmin decreased and cytokeratins appeared in the surface epithelial cells. New changes in cytokeratin expression appeared with the differentiation of the embryonic cords in a sex-specific manner with gradual decrease of reactivity for cytokeratin 18. No immunoreaction to the neurofilament proteins was found at the present ages, and the germ cells were negative for intermediate filaments. The results show that desmin is expressed in several primitive ovarian and mesonephric cells even though they are not myogenic. The sexual differences emerge after the incipient formation of the genetically female gonad, as different organization of the internal epithelial tissue with different timing of changes in intermediate filament proteins when compared with the male gonad.     

Removal of cell surface heparan sulfate increases TACE activity and cleavage of ErbB4 receptor

Background  

Nuclear localization of proteolytically formed intracellular fragment of ErbB4 receptor tyrosine kinase has been shown to promote cell survival, and nuclear localization of ErbB4 receptor has been described in human breast cancer. Tumor necrosis factor alpha converting enzyme (TACE) initiates the proteolytic cascade leading to ErbB4 intracellular domain formation. Interactions between matrix metalloproteases and heparan sulfate have been described, but the effect of cell surface heparan sulfate on TACE activity has not been previously described.     

Reliability of egg morphology to detect conspecific brood parasitism in goldeneyes Bucephala clangula examined using protein fingerprinting

Eadie (1989) developed a method based on variation between females in egg length, width and weight to detect conspecific brood parasitism in the field: using these three egg measures, Euclidean distance between all pairs of eggs within a clutch is calculated, and if maximum Euclidean distance (MED) between any two eggs exceeds a threshold value the nest is considered parasitized. The MED method has been tested in Finnish and Scottish common goldeneye Bucephala clangula populations but the results have been contradicting. Here we use protein fingerprinting to assess the validity of the MED method. Data comprised 35 clutches of which we knew, based on protein fingerprinting, how many different females laid the clutch (range 1–5 females). The mean MED of non-parasitized clutches (laid by 1 female only) was 1.470 (95% CI: lower 1.169, upper 1.771; n=21) and that of parasitized clutches (laid by 2 or more females) was 3.654 (95% CL: lower 3.083, upper 4.225; n=14). Using a MED>3.0 as a criterion to identify parasitized clutches 89% of all clutches were classified correctly either parasitized or non-parasitized when compared to the identification based on protein fingerprinting. Clutch size and the number of females (beyond 2 females) did not affect the clutch MED, whereas the status of parasitism did. Repeatability of egg length, width and weight were: 0.63, 0.76 and 0.80, respectively, implying that, variation in these egg measures occurs among rather than within females. Our new results confirm that the MED method is reliable enough to detect parasitism in common goldeneye.