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101.
102.
Comparative morphology of acrogenous branch systems and phylogenetic considerations. II. Angiosperms
Wolfgang Hagemann 《Acta biotheoretica》1990,38(3-4):207-242
A concept for a primitive angiospermous branch system is given in order to have a starting point for the derivation of the diverse and highly differentiated branch systems observed in contemporary angiosperms. Hitherto Troll's (1964, 1969) comparative study of the synflorescences in this plant group — developed out predominantly on herbaceous plants — was the most comprehensive and sophisticated treatment dealing with branch systems. Unfortunately, the work on tropical tree architecture by Hallé et al. (1978) has no reference to the classical studies of Troll and his pupils. Thus Müller-Doblies and Weberling (1984) emphasized the high degree of terminological incompatibility between the two works. Angiosperms are seen as a monophyletic plant division. Consequently, the branch system of the first primitive angiosperms must be the starting point in the evolution of the abundant diversity of branch systems and growth forms of modern angiosperms. If it is accepted that primitive angiospermous shoots were terminated by a large flower, one may assume, that the reproductive end of the shoot was enriched by paracladia early in evolution, thereby developing a terminal inflorescence instead of a single flower. Thus the primitive shoot unit was divided into a basal vegetative region — the trophotagma, branching retardively — and the reproductive terminal region, the anthotagma, branching simultaneously. It is demonstrated through a selection of different examples, that the construction of such a system possesses the options for several modifications, enabling the evolution of the abundant diversity of branch systems which characterizes contemporary angiosperms. 相似文献
103.
Beim maulbrütenden Cichliden Pseudocrenilabrus multicolor übernimmt ausschließlich das ♀ die Brutpflege. Es laicht die Eier portionsweise ab und nimmt sie sofort in das Maul auf. Die Brutpflegebereitschaft entsteht während der der Eiabgabe vorausgehenden Initiallaichphase in mehreren Schritten: Zunächst werden angebotene Eier gefressen, dann ausgespuckt und schließlich im Maul behalten. Versuche mit Unterbrechung des Laichaktes zu verschiedenen Zeitpunkten der Initiallaichphase zeigten, daß die Umstimmung nicht spontan eintritt, sondern vom Ablaichverhalten abhängt. Weitere Versuche lassen vermuten, daß die Umstimmung an die Ausführung von Laichbewegungen des ♀ gebunden ist. Die Laichbewegungen wiederum unterliegen in ihrer zeitlichen Organisation einer endogenen Steuerung durch das ♀ selbst. Die Funktion des ♂ beschränkt sich in diesem Zusammenhang auf die Bereitstellung der Auslösereize für die Bewegungen des ♀. Der Mechanismus der Umstimmung wird erörtert und mit Ergebnissen bei anderen Tieren verglichen. 相似文献
104.
Rapid cataloging of ribonuclease T1 resistant oligonucleotides from ribosomal RNAs for phylogenetic studies 总被引:3,自引:0,他引:3
Erko Stackebrandt Wolfgang Ludwig Karl-Heinz Schleifer Hans J. Gross 《Journal of molecular evolution》1981,17(4):227-236
A rapid and simple method of oligonucleotide cataloging for phylogenetic studies is presented. It involves in vitro 5'-32P-labelling of RNase T1 - resistant oligonucleotides of ribosomal 16S RNA and finger-printing by high voltage electrophoresis and gradient thinlayer chromatography. Oligonucleotide sequences are established by the mobility shift method, using controlled alkali cleavage, high voltage electrophoresis and homochromatography. These procedures facilitate in particular the analysis of long RNase T1 - resistant oligonucleotides. Oligonucleotide catalogs are established fo three Actinomycetes, namely Oerskovia turbata, Actinoplanes philippinensis and Ampullariella regularis. These catalogs are equivalent to those obtained by methods which were described by Sanger and Woese. 相似文献
105.
The use of azidoarylimidoesters in RNA-protein cross-linking studies with Escherichia coli ribosomes
Jutta Rinke Marlis Meinke Richard Brimacombe Gerald Fink Wolfgang Rommel Hugo Fasold 《Journal of molecular biology》1980,137(3):301-314
A series of related hetero-bifunctional RNA-protein cross-linking reagents has been prepared, carrying an imidoester or N-hydroxysuccinimide ester function at one end of the molecule, and a phenylazido function at the other. These compounds have been applied to RNA-protein cross-linking studies with ribosomal subunits, and one of them, p-azido-phenylacetic imidoester, has proved to be a particularly useful reagent for this purpose. The reagent first reacts specifically with protein amino groups, and subsequent photolysis of the azide group leads to cross-linking to the RNA in yields of up to 8% of the total protein. The whole reaction takes place under very mild conditions in aqueous solution.The individual proteins concerned in the cross-links have been identified by two-dimensional gel electrophoresis, and the existence of a covalent cross-link was confirmed by the isolation by two different methods of protein-oligonucleotide complexes carrying a 32P label. Although most of the ribosomal proteins could be cross-linked to their corresponding ribosomal RNA within the individual subunits, RNA-protein cross-links at the ribosomal subunit interface were only detectable in vanishingly small amounts.The advantages of this type of genuine hetero-bifunctional reagent in RNA-protein cross-linking studies are discussed. 相似文献
106.
Summary H-Y antigen was determined in eight transsexual patients. Two of the four male-to-female transsexual patients typed as H-Y antigen-negative, while the other two typed as expected from their phenotypic and gonadal sex, namely H-Y antigen-positive. Of the four female-to-male transsexual patients, three typed as H-Y antigen-positive and one was H-Y antigen-negative, as expected. The presence of normal testes in H-Y antigen-negative males is assumed to result from a mutation of nucleotide sequences of the H-Y structural gene for antigenic determinants. Thus, an H-Y is produced with normal receptor-binding activity which can sustain the testis determination of the bipotent gonadal anlage. In the case of H-Y antigen-positive females with normal ovaries a deletion of the autosomally located H-Y structural gene is assumed. This deletion should affect sequences for repressor-binding (as was suggested for H-Y antigen-positive XX-males) and for receptor-binding activity of the H-Y antigen molecule. The resulting H-Y antigen is unable to bind to the gonadal receptor of the bipotent gonadal anlage. Thus an ovary is determined. The relevance of H-Y antigen for the aetiology of transsexualism is discussed. 相似文献
107.
108.
Biological activity of the antitumor protein neocarzinostatin coupled to a monoclonal antibody by N-succinimidyl 3-(2-pyridyldithio)-propionate 总被引:6,自引:0,他引:6
Gundram Jung Wolfgang Köhnlein Gerd Lüders 《Biochemical and biophysical research communications》1981,101(2):599-606
The chromophore free apoprotein of neocarzinostatin was coupled to monoclonal IgG1 antibody using N-Succinimidyl 3-(2-pyridyldithio)-propionate as heterobifunctional reagent. After coupling active chromophore was reassociated with the apoprotein. We present here experimental evidence that the hybrid protein retains biological activity as measured by the degradation of T2-DNA and bacteriostatic action. 相似文献
109.
110.