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71.
A method has been developed for the study of somatostatin (SS) binding to dissociated cells from rat cerebral cortex. Binding of [125I][Tyr11]SS to cells obtained by mechanical dissociation of rat cerebral cortex was dependent on time and temperature, saturable, reversible and highly specific. Under conditions of equilibrium, i.e., 60 min at 25°C, native SS inhibited tracer binding in a dose-dependent manner. The Scatchard analysis of binding data was linear and yielded a dissociation constant of 0.60±0.08 nM with a maximal binding capacity of 160±16 fmol/mg protein. The binding of [125I][Tyr11]SS was specific as shown in experiments on tracer displacement by the native peptide, SS analogues, and unrelated peptides. 相似文献
72.
73.
74.
DNA Segments Sensitive to Single-Strand-Specific Nucleases Are Present in Chromatin of Mitotic Cells
It was observed before that DNAin situin chromatin of mitotic cells is more sensitive to denaturation than DNA in chromatin of interphase cells. DNA sensitivity to denaturation, in these studies, was analyzed by exposing cells to heat or acid and using acridine orange (AO), the metachromatic fluorochrome which can differentially stain double-stranded (ds) vs single-stranded (ss) nucleic acids, as a marker of the degree of DNA denaturation. However, without prior cell treatment with heat or acid no presence of single-stranded DNA in either mitotic or interphase cells was detected by this assay. In the present experiments we demonstrate that DNAin situin mitotic cells, without any prior treatment that can induce DNA denaturation, is sensitive to ss-specific S1 and mung bean nucleases. Incubation of permeabilized human T cell leukemic MOLT-4, promyelocytic HL-60, histiomonocytic lymphoma U937 cells, or normal PHA-stimulated lymphocytes with S1 or mung bean nucleases generated extensive DNA breakage in mitotic cells. DNA strand breaks were detected using fluorochrome-labeled triphosphonucleotides in the reaction catalyzed by exogenous terminal deoxynucleotidyl transferase. Under identical conditions of the cells’ exposure to ss-specific nucleases, DNA breakage in interphase cells was of an order of magnitude less extensive compared to mitotic cells. The data indicate that segments of DNA in mitotic chromosomes, in contrast to interphase cells, may be in a conformation which is sensitive to ss nucleases. This may be a reflection of the differences in the torsional stress of DNA loops between interphase and mitotic chromatin. Namely, greater stress in mitotic loops may lead to formation of the hairpin-loop structures by inverted repeats; such structures are sensitive to ss nucleases. The present method of detection of such segments appears to be more sensitive than the use of AO. The identification of mitotic cells based on sensitivity of their DNA to ss nucleases provides an additional method for their quantification by flow cytometry. 相似文献
75.
Fully developed thalli of Chondrus crispus, Gracilaria chilensis, Gymnogongrus furcellatus and Mazzaella laminarioides were used to assess tissue compatibility. The effect of thallus polarity on grafting and regeneration was also evaluated. Fusion did occur between fragments of the same life history phase in C. crispus, G. chilensis, G. furcellatus and M. laminarioides. Fusion between sporophytic and gametophytic tissue occurred in C. crispus, G. chilensis and M. laminarioides. Intergeneric fusion was observed between C. crispus and M. laminarioides, but not between G. chilensis and G. furcellatus.Outer cell wall, cortex and medulla were continuous at the contact face in compatible combinations. Medullary cells in the attached fragments were thinner and longer than normal cells, forming an interwoven scar plate. Thallus polarity did not modify fusion and regeneration. 相似文献
76.
Xp-duplications with and without sex reversal 总被引:5,自引:0,他引:5
Annette Baumstark Gotthold Barbi Mahmoud Djalali Claudia Geerkens Beate Mitulla Torsten Mattfeldt José Carlos Cabral de Almeida Fernando Regla Vargas Juan Clinton Llerena Jr Walther Vogel Walter Just 《Human genetics》1996,97(1):79-86
Duplications in Xp including the DSS (dosage sensitive sex reversal) region cause male to female sex reversal. We investigated two patients from families with Xp duplications. The first case was one of two sisters with karyotype 46,XY, der(22), t(X;22)(p11.3;p11)mat and unambiguous female genitalia. The living sister was developmentally retarded, and showed multiple dysmorphic features and an acrocallosal syndrome. The second case was a boy with a maternally inherited direct duplication of Xp21.3-pter with the breakpoint close to the DSS locus. He had multiple abnormalities and micropenis, but otherwise unambiguous male genitalia. We performed quantitative Southern blot analysis with probes from Xp22.13 to p21.2 to define the duplicated region. Clinical, cytogenetic, and molecular data from both patients were compared with those of previously reported related cases. A comparison of the extragenital symptoms revealed no differences between patients with or without sex reversal. In both cases, the symptoms were non-specific. Among 22 patients with a duplication in Xp, nine had unambiguous female genitalia and a well-documented duplication of the DSS region. Two patients with duplication of DSS showed ambiguous external genitalia. From these data, we conclude that induction of testicular tissue may start in these patients, but that the type of genitalia depends on the degree of subsequent degeneration by a gene in DSS. 相似文献
77.
We have created a catalogue comprising all viroid and viroid-like RNA sequences which to our knowledge have been either published or were available from on-line sequence libraries as of October 1, 1995. In the development of this catalogue nomenclature ambiguities were removed, the likely ancestral sequence of most species was determined and the most stable secondary structures of these sequences were predicted using the MulFold package. Only viroids of PSTVd-type possessed a rod-like secondary structure, while most other viroids adopted branched secondary structures. Several viroids have predicted secondary structures that include either a Y or cruciform structure reminiscent of the tRNA-like end of virus genomes at an extremity. However, it remains unknown whether or not these predicted structures are adopted in solution, and if they serve a particular function in vivo. Additional information such as the position of the self-catalytic domains are included in the catalogue. An analysis of the data compilated in the catalogue is included. The catalogue will be available on the world wide web (http://www.callistro.si.usherb.ca/jpperra), on computer disk and in printed form. It should provide an excellent reference point for further studies. 相似文献
78.
Relationship between the levels of wheat-rye metaphase I chromosomal pairing and recombination revealed by GISH 总被引:3,自引:0,他引:3
The metaphase I and anaphase I stages of meiosis of wheat×rye hybrids carrying the ph1b mutation were analyzed by genomic in situ hybridization. This technique allows distinction between three different types of
wheat-rye associations in metaphase I configurations as well as detection of wheat-rye recombinant chromosomes in anaphase
I cells. The frequency of associations between wheat and rye chromosomes greatly exceeded the level of wheat-rye recombination
found in the three hybrids examined. Extremely distal associations, which account for about 50% of the total wheat-rye metaphase
I chromosomal pairing, can explain such a discrepancy between metaphase I and anaphase I data. It is further discussed whether
these associations reflect very distally located chiasmata or nonchiasmatic pairing. The sizes of the segments exchanged in
wheat-rye recombinant chromosomes provide cytological evidence that wheat-rye recombination is restricted to the distal chromosomal
regions.
Received: 24 August 1995; in revised form: 27 February 1996 / Accepted: 28 March 1996 相似文献
79.
Akihiro Ohira Eugene de Juan Jr Yasuo Tano Charles A. Wilson 《The Histochemical journal》1996,28(9):607-611
Summary It has been proposed that basic fibroblast growth factor (basic FGF) mediates the neovascular response in a variety of conditions,
including diabetic retinopathy and branch retinal vein occlusion. To test the hypothesis that basic FGF was released from
retinal stores as a result of retinal ischaemia, transient retinal ischaemia was induced, followed by 48 h of reperfusion,
in the rat by combined central retinal vasculature and optic nerve ligation. The immunolocalization of basic FGF was studied
in the retina. We found that basic FGF in the normal retina is present around the deeper retinal vessels and in the neuronal
tissue of the outer plexiform layer. In the eyes that had ischaemia followed by reperfusion, there was moderate cellular oedema
with retinal swelling, and mitoses in the inner nuclear and plexiform layers. There were no changes evident at the immunohistochemical
level either in the intensity or distribution of stores of basic FGF. We conclude from these data that stores of basic FGF
are not altered dramatically under the conditions of transient experimental ischaemia and reperfusion in the rat, despite
the presence of cellular proliferation. 相似文献
80.
Thehigh growth(hg) locus in mice produces a 30–50% increase in weight gain of homozygous individuals. Here we report that the microsatellite markerD10Mit69is deleted in high growth mice. The deletion ofD10Mit69was uncovered in a screen of the high growth mouse and its progenitor strains for available markers in thehgregion. We demonstrate thathgandD10Mit69cosegregate in a cross of congenic strains C57BL/6J-hghg× C57BL/6J. These results suggest that deletion of a region aroundD10Mit69is responsible for the high growth effect. MarkerD10Mit69will be utilized as an entry point to physical cloning of thehg-containing segment. A dense map of markers aroundhgconstructed here should allow identification of markers in homologous regions in domestic animals and humans, which may be utilized to assess the role of thehglocus in these other species. 相似文献