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  • 1
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    STUTTGART, NEW YORK: G. FISCHER
    Call number: QP501Z:5/12,3
    Keywords: Somatostatin
    Pages: 40 S., 28 ABB.
    ISBN: 3-437-10614-7
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  • 2
    ISSN: 1432-0983
    Keywords: Mitochondrial DNA ; Cybrids ; B. napus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An important mitochondrial (mt) DNA polymorphism was detected by SalI restriction enzyme analysis in five Brassica napus cybrids plants which combine B. napus chloroplasts and a cytoplasmic male sterility (cms) trait from Raphanus sativus. Novel restriction fragments observed in these cybrids were analysed. One of them was found to be constituted by fragments of both parent mt genomes. Sites involved in rut recombination in cybrids were compared by molecular hybridization to sites supposedly implicated in intragenomic mt recombination in B. oleracea The results indicate that mt recombination events arising through protoplast fusion involve several different rut DNA regions. Some of these regions appeared homologous to regions presumably involved in intragenomic mt recombination in B. oleracea.
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  • 3
    ISSN: 1432-0983
    Keywords: Mitochondrial DNA ; Cytoplasmic male sterility ; Phaseolus coccineus ; Phaseolus vulgaris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To identify regions of the mitochondrial genome that potentially could specify cytoplasmic male sterility (CMS) in Phaseolus coccineus (including P. polyanthus), and to define differences amongst P. coccineus lines, mitochondrial (mt)DNA restriction patterns and Southern blots of total DNA from sterile and fertile lines were analysed. By restriction endonuclease mapping we isolated a region which was specific to CMS lines flanking an F1-ATPase α-subunit (atpA) gene. DNA sequence analysis of this region showed 99.9% homology to the region previously isolated from P. vulgaris CMS Sprite. A high frequency of plants carrying the CMS-fragment was observed in a wild Phaseolus population, perhaps explaining the occurrence of inter- and intraspecific gene flow observed in the autogamous species P. vulgaris.
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  • 4
    ISSN: 1432-0983
    Keywords: Brassica ; Ogura cytoplasmic male-sterility ; Cybrids ; Mitochondrial DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Spontaneous reversion to fertility was studied in the progeny of a cytoplasmic male-sterile (CMS) Brassica napus cybrid containing recombinant B. napus/Ogura radish mitochondrial genomes. This reversion is concomitant with the disappearance of a 2.5 kb NcoI fragment present in the mitochondrial DNA of Ogura radish, and of CMS cybrids derived from plants carrying Ogura cytoplasm, and absent in the mitochondrial genome of normal Brassicas and fertile cybrids. This specific fragment hybridizes to a 1.4 kb transcript found only in male-sterile plants bearing an Ogura derived cytoplasm.
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  • 5
    ISSN: 1432-0568
    Keywords: Brattleboro ; Hypothalamus ; Neurohypophysis ; Glycoprotein ; Vasopressin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary L-3H-fucose was injected into the lateral cerebral ventricle of vasopressin-deficient Brattleboro and control Long-Evans rats which were subsequently killed at several time intervals after the injection. The hypothalamus and the neurohypophysis were processed for light- and electronmicroscopic radioautography. Other complementary experiments using immunocytochemical and enzyme-histochemical techniques were also undertaken. L-3H-fucose was incorporated into newly synthesized glycoproteins in the Golgi apparatus of supraoptic and paraventricular neurons, and later on labelled glycoproteins migrated to lysosomes and the plasma membrane surrounding the perikaryon. The Golgi apparatus of the vasopressin-deficient neurons remained heavily labelled as long as 3 days after injection, in sharp contrast with the normal neurons in which there was a remarkable decrease of label in the Golgi region between 4 and 24 h after the isotope administration. Labelled glycoproteins also migrated to the neurohypophysis and were mainly found in the axonal plasma membrane, vesicles and axoplasm. The renewal of glycoproteins in the neurohypophysis of Brattleboro rats was faster than in the normal rats and this was attributed to the lack of formation of products which are normally packaged in secretory granules in the perikaryon and released at the axon terminal in the neurohypophysis. Colchicine caused a disturbance in the topography of the organelles of the perikaryon and the most striking features were the displacement of Golgi stacks to the periphery of the perikaryon and an accumulation of mitochondria in this neuronal region. No secretory granules were observed in the vasopressin-deficient neurons of untreated or colchicine-treated Brattleboro rats. By contrast, secretory granules (most of them labelled with 3H-fucose) were concentrated in the perikaryon of colchicinetreated Long-Evans rats. In these rats, colchicine caused a severe block in the migration of 3H-fucose-labelled glycoproteins to the neurohypophysis, but this did not occur in the Brattleboro rats. The results of the experiments were interpreted in the light of the genetic defect known to occur in Brattleboro rats which causes the inability to produce vasopressin and also remarkable morphological and physiological changes in the affected neurons.
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  • 6
    ISSN: 1432-0568
    Keywords: Ontogeny ; 3β-HSD ; Rat testis ; Immunocytochemistry ; Leydig cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The enzymatic complex 3β-hydroxysteroid dehydrogenase/Δ 5-Δ 4 isomerase (3β-HSD) is a step essential in the biosynthesis of all biologically active steroids, including androgens. In order to obtain information about the expression of 3β-HSD during testis development, we have localized this enzyme by light microscope immunocytochemistry during fetal and postnatal periods of development in the rat. In fetal testis, the enzyme was first detected in a few Leydig cells on the 17th day of gestation. The number of labeled cells and intensity of labeling increased with fetal developmeent. From days 19 to 21 of gestation, strongly immunoreactive Leydig cells were arranged in clusters between seminiferous tubules. During the first days following birth, the number and size of positive cells rapidly decreased so that on postnatal days 5 and 10 only small, poorly stained cells could be seen. Fifteen days after birth, positive Leydig cells appeared more numerous and localized in peri- and intertubular spaces. At the onset of puberty, the intensity of labeling markedly increased. After puberty, and during adulthood, both strongly and weakly stained Leydig cells were mainly localized in intertubular spaces. Since the fluctuations in 3β-HSD content revealed in the present study by immunocytochemistry appear similar to those already observed for androgen secretion, such data suggest that regulation of 3β-HSD by trophic hormones might play an important role in regulating testicular androgen production during fetal as well as postnatal development.
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  • 7
    ISSN: 1432-0568
    Keywords: Benzodiazepine receptors ; Diazepam-binding inhibitor ; Rat ovary ; In situ hybridization ; Steroid-secreting cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Diazepam-binding inhibitor (DBI) is the precursor of a family of peptides, including an octadecaneuropeptide (ODN), that share with DBI the ability to specifically displace benzodiazepines (BZD) from their receptors. An association of ODN with the peripheral type BZD receptors (PBR) has been reported in the brain and a few peripheral tissues. In order to investigate whether DBI and PBR are present in ovarian tissue, we have localized DBI by means of immunocytochemistry, in situ hybridization and autoradiography of PBR in the rat ovary. Immunocytochemical localization was achieved by means of rabbit antibodies developed against rat ODN. Immunostaining was located in the cytoplasm of the theca interna, corpus luteum and interstitial gland cells, but not in the granulosa cells. Hybridization signal obtained following in situ hybridization with a [35S1]-labelled single-stranded RNA probe complementary to DBI mRNA was observed in all the steroid-secreting cells, including granulosa cells of developing and mature follicles. Autoradiographic localization of PBR obtained by incubating ovary sections with [3H] PK11195, a ligand selective for PBR, revealed the presence of specific labelling in all the steroid-secreting cells. These results, which demonstrate for the first time that the ovarian steroid-secreting cells contain both PBR and its endogenous ligand, suggest that the BZD receptor might be involved in the regulation of ovarian function.
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  • 8
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neurosteroids may play a major role in the regulation of various neurophysiological and behavioural processes. However, while the biochemical pathways involved in the synthesis of neuroactive steroids in the central nervous system are now elucidated, the mechanisms controlling the activity of neurosteroid-producing cells remain almost completely unknown. In the present study, we have investigated the effect of the octadecaneuropeptide (ODN), an endogenous ligand of benzodiazepine receptors, in the control of steroid biosynthesis in the frog hypothalamus. Glial cells containing ODN-like immunoreactivity were found to send their thick processes in the close vicinity of neurones expressing the steroidogenic enzyme 3β-hydroxysteroid dehydrogenase. Exposure of frog hypothalamic explants to graded concentrations of ODN (10−10−10−5m) produced a dose-dependent increase in the conversion of tritiated pregnenolone into various radioactive steroids, including 17-hydroxypregnenolone, progesterone, 17-hydroxyprogesterone, dehydroepiandrosterone and dihydrotestosterone. The ODN-induced stimulation of neurosteroid biosynthesis was mimicked by the central-type benzodiazepine receptor (CBR) inverse agonists methyl β-carboline-3-carboxylate (β-CCM) and methyl 6,7-dimethoxy-4-ethyl-β-carboline-3-carboxylate (DMCM). The stimulatory effects of ODN, β-CCM and DMCM on steroid formation was markedly reduced by the CBR antagonist flumazenil. The ODN-evoked stimulation of neurosteroid production was also significantly attenuated by GABA. Collectively, these data indicate that the endozepine ODN, released by glial cell processes in the vicinity of 3β-hydroxysteroid dehydrogenase-containing neurones, stimulates the biosynthesis of neurosteroids through activation of central-type benzodiazepines receptors.
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  • 9
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A dense network of neuropeptide Y (NPY)-like immunoreactive (NPY-LI) fibres was revealed in the ovine pineal gland at the light microscope level. The dorsal and peripheral regions of the gland contained the most dense concentration of NPY-LI fibres with relatively few fibres in the mid-region and almost none in the pineal stalk. The effect of NPY in conjunction with isoproterenol (ISO) on cyclic AMP (cAMP) accumulation and noradrenaline (NA) on melatonin synthesis was investigated using in vitro techniques. NPY had no effect on the stimulation of cAMP or melatonin synthesis by the adrenergic agonists.
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  • 10
    ISSN: 1617-4623
    Keywords: Brazil nut ; Brassica napus ; 2S albumin ; Transgenic plants ; Tissue specific expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The methionine rich 2S albumin seed storage protein of Bertholletia excelsa has been expressed in seeds of Brassica napus (rapeseed). A chimeric gene driven by the soybean lectin 5′ flanking regions was used to produce a fusion protein consisting of the soybean lectin signal peptide and the propeptide of the Brazil nut 2S albumin. Several transgenic plants were studied at the RNA and protein levels; in each case the chimeric gene was expressed and the protein detected at levels ranging from 0.02% to 0.06% of total protein. Transcriptional studies in a particular transgenic plant show that expression of the gene is tissue specific and developmentally regulated during seed maturation. The endogenous napin genes and the introduced gene are regulated differently, with expression of the chimeric gene paralleling that seen when the soybean lectin gene is expressed in other plant species. Western analysis using antibodies to Brazil nut 2S albumins resulted in the detection of a protein whose size is consistent with correct processing of the precursor.
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