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Biomedical subjects

A Dorn

Publications and source records attributed to A Dorn.

At least 73 records · Page 4Linked to original sources
PubMed1987

Properties of a CCAAT box-binding protein.

NF-Y is a sequence-specific DNA-binding protein that interacts with the conserved Y motif of the major histocompatibility complex class II gene, E alpha. Since it is actually a CCAAT box-binding protein, NF-Y also attaches to other promoters bearing CCAAT sequences; yet, it is neither of the previously described transcription factors, CBP or CTF/NF-1. In this report, we document the cell-type distribution and various biochemical properties of NF-Y. The most important findings are that this protein is ubiquitously distributed, that it is probably a metallo-protein, that it has a protease-resistant DNA-binding domain and that the NF-Y/E alpha-olgo complex seems extremely large (greater than 200kD). These data should prove useful in comparisons of NF-Y with other sequence-specific DNA-binding proteins; they have already provided new insights into NF-Y's structure.

Animals↗
PubMed1987

A multiplicity of CCAAT box-binding proteins.

NF-Y is a sequence-specific DNA-binding protein that recognizes the Y box, a promoter element common to all major histocompatibility complex class II genes. Since the 14-base Y element harbors a CCAAT box in reverse, we were prompted to ask whether NF-Y is actually a CCAAT box-binding protein and whether it is related to the previously described CCAAT-binding factors CBP and CTF/NF-I. Data from gel retardation, methylation interference, saturation mutagenesis, and cross-competition experiments establish definitively that NF-Y is an entirely distinct CCAAT box-binding entity. Moreover, these experiments have uncovered a fourth CCAAT-binding protein, NF-Y(star) that interacts with the thymidine kinase promoter. Clearly, then, there exists a multiplicity of factors that recognize CCAAT sequences; it now becomes imperative to understand the functional significance of this multiplicity.

Animals↗
PubMed1987

Prothoracicotropic hormone activity in the embryonic brain of the tobacco hornworm, Manduca sexta.

Head segments and brains were extirpated from embryos of the tobacco hornworm, Manduca sexta, extracted and the resulting extracts assayed for prothoracicotropic hormone (PTTH) activity on prothoracic glands from day 3 fifth instar larvae and day 0 pupae. Dose-response curves were generated and indicated the presence of PTTH activity in embryonic brains and head segments, suggesting a role(s) for this neurohormone during embryogenesis. Maximal PTTH activity was found in brains from embryos 117 h post-oviposition, just prior to hatching, but activity was also noted in head segments as early as 24 h post-oviposition. These data on PTTH and those on ecdysteroids and juvenile hormones in embryos suggest that these 3 classes of hormones which control insect post-embryonic development, may also be involved in the regulation of developmental processes in the embryo.

Animals↗
PubMed1987

Immunolocalization of dipeptidyl aminopeptidase (DAP IV) in the developing human brain.

By means of immunohistochemical techniques we have investigated the presence of dipeptidyl aminopeptidase IV immunoreactivity in brain material derived from human fetuses, newborns and aged persons. It was revealed that the enzyme protein is abundantly present in the immature human CNS. On the contrary the adult human brain contains much less dipeptidyl aminopeptidase immunoreactivity. It is speculated that the enzyme might play an important role in neuronal proliferation and/or differentiation especially with regard to its possible action on certain neuronotrophic peptides (IGF II, growth hormone).

Aged↗
PubMed1987

Immunohistochemical localization of L-ornithine decarboxylase in developing rat brain.

L-Ornithine decarboxylase, the rate limiting enzyme of polyamine biosynthesis and a marker enzyme of tissue proliferation and maturation, was localized immunocytochemically in the developing rat central nervous system. It can be noted that the distribution of the enzyme protein underlies temporal alterations. Conclusions are drawn from the localization of the enzyme and possible functional roles played by ornithine decarboxylase in discrete brain areas.

Animals↗
PubMed1987

Immunohistochemical detection of cathepsin D in human neuroontogenesis.

An antiserum against rat liver cathepsin D, which was previously found to cross-react with human brain cathepsin(s) D, was used to immunolocalize the enzyme in developing CNS man. Cathepsin D protein was found in neurons as well as in glial cells. The aerliest occurrence of cathepsin D was observed in neuroblasts at the 12th gestational week. During pre-, peri-, and postnatal neuroontogenesis, there is a strong increase in the amount of immunoreactive material.

Brain↗
PubMed1987

Proteolytic degradation of insulin and glucagon in rat brain during ontogenesis.

The degradation of insulin and glucagon was investigated in rat brain, kidney, and liver during postnatal ontogenesis. It was found that a maximal activity around 13 d is unique for CNS and differs remarkably from time-course in liver and kidney. It is concluded that this result supports the hypothesis of a growth promoting role of insulin in developing rat brain.

Aging↗
PubMed1987

Conserved major histocompatibility complex class II boxes--X and Y--are transcriptional control elements and specifically bind nuclear proteins.

A conserved sequence motif exists at the 5' end of all major histocompatibility complex class II genes. This motif consists of the 14-base X and Y boxes separated by a short stretch of variable sequence. In this report, we provide evidence that the X and Y boxes play an important role in controlling transcription of the murine class II gene E kappa alpha. We have developed transgenic mouse lines that carry E alpha genes cleanly deleted for either the X or Y box and have compared the expression of these mutant transgenes with that of a nondeleted control. Both the X and Y segments appear critical for accurate and efficient transcription of E kappa alpha. The most drastic effect is seen with gamma-interferon-treated macrophages, where deletion of the Y box completely abrogates transcription initiated by the normal promoter. In addition, we identify proteins from nuclear extracts that bind specifically to the X or Y box.

Animals↗
PubMed1986

Sponge aggregation factor: in situ localization by fluorescent monoclonal antibody techniques.

The aggregation factor (AF) from sponges mediates a heterophilic interaction of homologous cells. Applying electron microscopical means, we succeeded only very rarely in identifying the 90 S AF particle in tissue sections from Geodia cydonium. By means of a fluorescent antibody technique, we have now localized the cell binding domain of the AF in situ. Previous studies in this laboratory have led to the identification of the 47-kDa cell binding protein of the AF, using the monoclonal antibody (mab) 5D2-D11 [Gramzow M, Bachmann M, Zahn RK, Uhlenbruck G, Dorn A, Müller WEG, J Cell Biol, 102: 1344-1349, 1986]. This mab and mab 7D5, directed against a 92-kDa protein in the AF complex, were chosen for the fluorescent studies. By using mab 5D2-D11, the plasma membranes of cells from different regions in the sponge could be brightly stained. However, mab 7D5 reacted only very weakly with the sponge surfaces. By applying the immuno-blotting technique it was furthermore demonstrated that the cell binding protein is present both in the associated form with AF complex and in a free state. Moreover, it was established that the 47-kDa binding protein is not present in homologous glycoconjugates, lectin, or collagen; these components are known to be involved in cell-matrix interaction.

Animals↗
PubMed1986

Immunocytochemical detection of peptides in the guinea pig cochlea.

The cochleae of juvenile guinea pigs were investigated for the presence of several neuropeptides. Glucagon, insulin, CCK and beta-endorphin immunoreactive neurons and nerve fibers as well as hair cells were demonstrated by the peroxidase antiperoxidase technique. Small amounts of substance P were also found in different sites in the inner ear. In contrast, prolactin-like material could not be found at all. These findings have significance with regard to the putative role of neuropeptides in neuromodulation.

Animals↗
PubMed1986

Atrial natriuretic polypeptides in the specific atrial granules of the rat heart: immunohistochemical and immunoelectron microscopical localization and radioimmunological quantification.

Atria of several mammalian species contain atrial natriuretic polypeptides (ANP) with natriuretic, diuretic, and vasodilating activity. In the present studies ANP were localized and quantitated in different parts of the heart by immunocytochemical and radioimmunological methods. The concentration of immunoreactive ANP as determined by quantitative radioimmunoassay in rat heart atria was a follows (ng/mg, mean +/- SD, n = 5): right auricle (688 +/- 156), left auricle (556 +/- 156), right atrium (334 +/- 60), and left atrium (93 +/- 36). The staining intensities in immunohistochemical localizations were consistent with the quantitative data. The location of the peptides was sarcoplasmic and granular. The highest concentration of ANP was found in the perinuclear area of the atrial myocyte sarcoplasm, but some staining was also seen in the periphery of the cells. The indirect immunoelectron microscopical gold method showed that ANP are located in the specific atrial granules supporting previous findings.

Animals↗
PubMed1986

Proctolin immunoreactive neurons in the human brain stem.

Using the peroxidase-antiperoxidase (PAP) technique it could be established that a variety of nerve cells of human Pons and Medulla oblongata contain proctolin-like material. These neurons belong to the Nuc. olivaris caudalis, Nuc. originis n. hypoglossi, Nuc. raphes dorsalis and the Nuc. ambiguus. Furthermore, proctolin immunoreactive peptide was found to be contained in certain fiber systems (Lemniscus medialis and fiber tracts near the Raphe).

Aging↗
PubMed1986

Neuropeptides in macula utriculi and macula sacculi of guinea pig labyrinth. An immunohistochemical study.

The neuropeptides Substance P, beta-Endorphin, Prolactin, Cholecystokinin, and Glucagon were investigated by means of Sternbergers PAP technique in the neuroepithelium of the Maculae utriculi and sacculi of the labyrinth of newborn guinea pigs. This brief report will show the localization of some neuropeptides in the neuroepithelium of the Maculae utriculi and sacculi. We could not find information about similar studies on this topic in the literature. In connection with investigations of the sensory apparatus of the inner ear we have recently presented neuropeptides evidence for the presence of certain peptides in the Ggl. spirale and the hair cells of the organ of Corti. With this paper we continue to report on neuropeptides in the labyrinth of the juvenile guinea pig as revealed by immunohistochemistry (Nowak et al., in press).

Acoustic Maculae↗
PubMed1986

Immunoelectron microscopical location of the acid cysteine proteinase inhibitor in the lymphatic tissue of the tonsils.

Previous studies have shown the acid cysteine proteinase inhibitor (ACPI) to be a common characteristic of human squamous epithelial cells and dendritic reticulum cells (DRC) in lymphoid secondary follicles. In the present study, we used the PAP-preembedding technique for the immunoelectron microscopic identification of ACPI in DRC in palatine tonsillar tissue. ACPI appeared to be located in the cytoplasm of perikaryon and of dendritic processes of DRC on the membranes of the endoplasmic reticulum and the outer membrane of mitochondria. Further more, the tonofilaments and the desmosomal membranes exhibited a strong ACPI reactivity.

Adolescent↗
PubMed1986

Identification and further characterization of the specific cell binding fragment from sponge aggregation factor.

Monoclonal antibodies (McAbs) were raised against the aggregation factor (AF) from the marine sponge Geodia cydonium. Two clones were identified that secrete McAbs against the cell binding protein of the AF complex. Fab fragments of McAbs: 5D2-D11 completely abolished the activity of the AF to form secondary aggregates from single cells. The McAbs were determined to react with the AF in vitro; this interaction was prevented by addition of the aggregation receptor, isolated and purified from the same species. After dissociation of the AF by sodium dodecyl sulfate and 2-mercaptoethanol, followed by electrophoretical fractionation, a 47-kD protein was identified by immunoblotting which interacted with the McAbs: 5D2-D11. During this dissociation procedure, the sunburst structure of the AF was destroyed. In a second approach, the 47-kD protein was isolated by immunoprecipitation; 12 molecules of this protein species were calculated to be associated with the intact AF particle. The 47-kD AF fragment bound to dissociated Geodia cells with a high affinity (Ka of 7 X 10(8) M-1) even in the absence of Ca++ ions; the number of binding sites was approximately 4 X 10(6)/cell. This interaction was prevented by addition of the aggregation receptor to the 47-kD protein in the homologous cell system. Moreover, it was established that this binding occurs species-specifically. The 47-kD fragment of the AF was localized only extracellularly by indirect immunofluorescence staining in cryostat slices. These data suggest that the 47-kD protein is the cell binding molecule of the AF from Geodia.

Animals↗
PubMed1986

Sponge secondary metabolites: biochemical and ultrastructural localization of the antimitotic agent avarol in Dysidea avara.

The secondary metabolite avarol, a potent cytostatic and antibacterial sesquiterpenoid hydroquinone, is present in large amounts only in the sponge Dysidea avara (2.7 g avarol/1 kg of fresh material). The present study was designed to determine the storage site of this compound within the organism. Light and transmission electron microscopic studies revealed that avarol is probably stored only in spherular cells. The compound is compartmented in intracellular cytoplasmic vesicles in a paracrystalline form, and therefore can have no inhibitory effect on the sponge cells. Quantitative analysis utilizing high-pressure liquid chromatography revealed that avarol is present at a concentration of 3.2 micrograms/10(6) spherular cells. It appears that avarol is released from the cells into the extracellular space in a merocrine manner. We suggest that it is involved in regulating the bacteria with which the sponge is symbiotically associated.

Animals↗