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41.
42.
Genetic analysis of the high responder-non-(or low) responder differences between WF and ACI rats to the synthetic copolymers GT and GA established singleIr-genes for both antigens and dominance for high responder status.Ir-GT andIr-GA are linked to the major histocompatibility locus. It could be demonstrated that only T cells carrying the high responderIr-GT gene undergo in vitro blast transformation to GT. The advantages of the rat systems for further studies of the regulatory role ofIr-genes on the cellular level are discussed.Abbreviations cpm
counts per minute
- DHR
delayed hypersensitivity reaction
- GA
random synthetic copolymer of L-glutamic acid50, L-alanine50, M.W. 45,000
- GT
random synthetic copolymer of L-glutamic acid50, L-tyrosine50, M.W. 22,000
-
Ir gene
immune response gene
- MLC
mixed lymphocyte cultures
- LDH
lactic dehydrogenase
- (T,G)-A-L
branched chain synthetic polymer of poly-L (tyrosine, glutamic acid)-poly-D, L-alanine-poly-L-lysine
Rat Strains ACI
ACI/MaI
- WF
Wistar Furth
- AUG
August 28807/Cr 相似文献
43.
Enzymatic methylations: III. Cadaverine-induced conformational changes of E.coli tRNAfMet as evidenced by the availability of a specific adenosine and a specific cytidine residue for methylation+ 总被引:1,自引:1,他引:0 下载免费PDF全文
A partially purified tRNA methylase fraction from rat liver, containing m(2)G- m(1)A- and m(5)C-methylase, was used to study the influence of Mg(++) and of the biogenic polyamine cadaverine on the enzymatic methylation of E.coli tRNA(fMet)in vitro. In presence of 1 or 10 mM Mg(++), guanosine no. 27 was methylated to m(2)G. In 1 mM Mg(++) plus 30 mM cadaverine, guanosine in position 27 and adenosine in position 59 were methylated. In presence of 30 mM cadaverine alone tRNA(fMet) accepted three methyl groups: in addition to guanosine no. 27 and adenosine no. 59 cytidine no. 49 was methylated. In order to correlate tRNA(fMet) tertiary structure changes with the methylation patterns, differentiated melting curves of tRNA(fMet) were measured under the methylation conditions. It was shown that the thermodynamic stability of tRNA(fMet) tertiary structure is different in presence of Mg(++), or Mg(++) plus cadaverine, or cadaverine alone. From the differentiated melting curves and from the methylation experiments one can conclude that at 37 degrees in the presence of Mg(++) tRNA(fMet) has a compact structure with the extra loop and the TpsiC-loop protected by tertiary structure interactions. In Mg(++) plus cadaverine, the TpsiC-loop is available, while the extra loop is yet engaged in teritary structure (G-15: C-49) interactions. In cadaverine alone, the TpsiC-loop and the extra loop are free; hence under these conditions the open tRNA(fMet) clover leaf may be the substrate for methylation. In general, cadaverine destabilizes tRNA tertiary structure in the presence of Mg(++), and stabilizes tRNA(fMet) tertiary structure in the absence of Mg(++). This may be explained by a competition of cadaverine with Mg(++) for specific binding sites on the tRNA. On the basis of these experiments a possible role of biogenic polyamines in vivo may be discussed: as essential components of procaryotic and eucaryotic ribosomes they may together with ribosomal factors facilitate tRNA-ribosome binding during protein biosynthesis by opening the tRNA tertiary structure, thus making the tRNA's TpsiC-loop available for interaction with the complementary sequence of the ribosomal 5S RNA. 相似文献
44.
45.
46.
Differential staining of plant chromosomes with Giemsa 总被引:2,自引:2,他引:0
Dieter Schweizer 《Chromosoma》1973,40(3):307-320
Simple Giemsa staining techniques for revealing banding patterns in somatic chromosomes of plants are described. The value of the methods in the recognition of heterochromatin was demonstrated using five monocotyledonous and two dicotyledonous species. In Trillium grandiflorum the stronger Giemsa stained chromosome segments were shown to be identical with the heterochromatic regions (H-segments) revealed by cold treatment. Preferential staining of H-segments was also observed in chromosomes from three species of Fritillaria and in Scilla sibirica. Under suitable conditions the chromosomes of Vicia faba displayed a characteristic banding pattern and the bands were identified as heterochromatin. The Giemsa techniques proved to be more sensitive than Quinacrine fluorescence in revealing a longitudinal differentiation of the chromosomes of Crepis capillaris, where plants with and without B-chromosomes were examined. Again all chromosome types had their characteristic bands but there was no difference in Giemsa staining properties between the B-chromosomes and those of the standard complement. 相似文献
47.
Zusammenfassung In den Zellen der Nierentubuli (Malpighische Gefäße) von Drosophila melanogaster werden Lipide in der gleichen Weise wie das 3-Hydroxykynurenin gespeichert. Diese Substanzen werden in Erweiterungen des endoplasmatischen Retikulums akkumuliert. Bei älteren Larven verschwinden diese Lipidtropfen. Dabei legen sich entweder Mitochondrien um die Depots oder sie werden von Membranstapeln des endoplasmatischen Retikulums umgeben und abgebaut. Die funktionelle Bedeutung dieser Befunde wird diskutiert.
Diese Untersuchung wurde mit Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt. 相似文献
Electronmicroscopic studies on the lipid storage in the renal tubules of Drosophila melanogaster
Summary In the cells of the renal tubules (Malpighian tubules) of Drosophila melanogaster lipids are stored in the same way as 3-hydroxykynurenin. These substances are found in dilatations of the endoplasmic reticulum. In later larval stages the lipid droplets gradually disappear. In theses stages the lipid droplets are either closely associated with the mitochondria or they are removed by concentric membrane arrays of the endoplasmic reticulum. The functional significance of these findings is discussed.
Diese Untersuchung wurde mit Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt. 相似文献
48.
Dieter Zissler 《Cell and tissue research》1969,96(1):106-133
Zusammenfassung Bei Notodromas monacha (Ostracoda) wird die Entwicklung der Spermatiden von der Spindelbis zur Schlauchform mit Phasenkontrast und elektronenmikroskopisch untersucht. Am Kern der spindelförmigen Spermatiden sind an zwei gegenüberliegenden Seiten jeweils zwei Ausstülpungen der Membran zu beobachten. Aus ihnen werden offenbar unter Beteiligung von Vesikeln des endoplasmatischen Reticulum zwei Flügelstrukturen aufgebaut. Jede Flügelstruktur besteht aus zwei Lamellen, die mit tubulären Elementen besetzt sind. An den schlauchförmigen Spermatiden läßt sich ein dicker Körper und ein dünner Faden unterscheiden. Kern, Nebenkern-Derivate und Flügelstrukturen durchziehen den Körper der Länge nach. Der Faden enthält nur noch den Kern und die Ausläufer der Flügelstrukturen. Im Bereich des freien Körperendes liegt im Kern ein als Chromatin gedeuteter Kolben. Diesem folgt in Richtung zum Fadenende ein dichter Achsenstab, der von einer Doppelmembran umhüllt ist. Im dorso-lateralen Kernraum finden sich elektronendichte Brocken unbekannter Bedeutung. Nach Beendigung des Aufbaues der Flügelstrukturen wird das endoplasmatische Reticulum samt Mikrotubuli weitgehend abgebaut. Gleichzeitig verschwindet die den Achsenstab umhüllende Doppelmembran. Die Flügelstrukturen werden als das für die Motilität der Spermien verantwortliche Organell gedeutet.
The spermiogenesis of the fresh-water ostracod Notodromas monacha O. F. Müller
Summary The transformation of spindle-like spermatids into tubular forms in Notodromas monacha (Ostracoda) has been studied by means of phase contrast and electron microscopy. At each of two opposite sides of the nucleus of spindle-like spermatids, two extensions of the nuclear membrane arise. These extensions form two Flügelstrukturen (wing-like structures) obviously by participation of vesicles of the endoplasmic reticulum. Each Flügelstruktur consists of two lamellae, each bearing numerous tubules. The tube-like spermatids consist of a large body and a small thread. The nucleus, the Nebenkern-derivatives and the Flügelstrukturen extend through the whole body. Within the thread only the nucleus and the outermost parts of the Flügelstrukturen are found. A columnar body, supposed to be chromatin, is located within that part of the nucleus which is situated in the free end of the body. A dense axial rod extends between the columnar body and the free end of the thread. The dorso-lateral sphere of the nucleus contains electron dense particles of unknown function. As soon as the construction of the Flügelstrukturen is finished, the endoplasmic reticulum and the microtubules are reduced. Simultaneously the double-membrane surrounding the axial rod disappears. The Flügelstrukturen are interpreted as organelles responsible for the motility of the sperm.相似文献
49.
Dr. Dieter Schlee 《Zoomorphology》1969,64(2):95-138
The method for the search for synapomorphies (in the sense of Hennig) is demonstrated by the study of the system of sperm-transfer. The ground plan of sperm-transfer in Homoptera (and other insect groups) is peristaltic movement of circular muscles surrounding the ejaculatory duct. In contrast, Psyllina and Aleyrodina exhibit a completely different structure and function of the ejaculatory duct, being extremely specialized, and principally identical in both the groups. This is a synapomorphic complex which proves Psyllina and Aleyrodina as most closely related. Other synapomorphies confirm this statement. 相似文献
50.
Zusammenfassung Die in der Literatur beschriebenen Beziehungen zwischen Substantivität und chemischem Bau der in der Histochemie verwendeten Tetrazoliumsalze wurden an weiteren Tetrazoliumsalzen überprüft. Die Untersuchungen ergaben, daß die Anzahl und die Stellung der Nitrogruppen im Molekül an Bedeutung für die Substantivität des Tetrazoliumsalzes hinter dem Einfluß einer linearen, aromatischen Substitution am N(3) des Tetrazolringes bzw. einer Molekülverdoppelung zurücktreten. Es ist zwischen einer Substantivität der Tetrazoliumsalze und einer Substantivität der Formazane zu unterscheiden.
On substantivity of tetrazolium salts in histochemistry
Summary The known correlations between substantivity and chemical constitution of tetrazolium salts used in histochemistry are further examined on several tetrazolium salts. The investigations are demonstrating that number and position of the nitro groups in the molecule are less important for substantivity of the salt than the influence of a linear, aromatic substitution on N(3) of the tetrazol ring or of doubling the molecule. It is to differentiate between substantivity of tetrazolium salts and the substantivity of the formazans.相似文献