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61.
A. E. Retief J. A. Van Zyl R. Menkveld M. F. Fox G. M. Kotzè J. Brusnický 《Human genetics》1984,66(2-3):162-164
Summary Chromosome studies were performed on 106 men with azoospermia and 390 men with oligozoospermia (consistant sperm count below 10 million/ml). Constitutional chromosome abnormalities were found in 14.1% of the azoospermia group and in 5.1% of the oligozoospermia group. An overall incidence of 7.1% constitutional abnormalities indicates that this criterion of selection may be advisable for routine chromosome analysis of infertile men. A reduction of 25% in the workload increases the yield of chromosome abnormalities in the group of infertile men to 10–14 times above that expected in the normal population. 相似文献
62.
Zusammenfassung In der vorgelegten Arbeit wurde die sogenante deduktive Klassifikationsmethode der anthropogenen Pflanzengesellschaften behandelt. Diese Methode geht vom System der höheren Vegetationseinheiten der Braun-Blanquet Schule aus. Sie ermöglicht die syntaxonomische Bearbeitung zahlreicher anthropogener Gesellschaften unserer Kulturlandschaft, die nur aus Arten mit breiterer ökologischer und zönologischer Amplitude zusammengesetzt sind, und zwar ohne unerwünschte Verwechslung der Bestimmungsmerkmale einzelner Rangstufen des Systems (Klassen-, Ordnungs-, Verbands- und Assoziationskenn-und trennarten). Die Grundprinzipien der Methode wurden schon früher von Kopecký & Hejný (1971, 1973, 1974) und Kopecký (1976) erläutert. Die vorliegende Arbeit bringt eine präzisierte Auslegung der Methode auf Grund neuer Erfahrungen, die bei der Bearbeitung der spontan entstandenen strassenbegleitenden Gesellschaften derMolinio-Arrhenatheretea Tx. 1937 in Nordostböhmen gewonnen wurden. Aus dem reichen Aufnahmematerial werden nur einige Aufnahmen der Basalgesellschaften mitAlopecurus pratensis und der von ihnen abgeleiteten Derivatgesellschaften mitDactylis glomerata undAgropyron repens fur die anschauliche Demonstration der Methode beigegeben (Tab. 1 und 2). Die Aufnahmen der übrigen Gesellschafts-typen werden in einer anderen Arbeit (Kopecký 1978) veröffentlicht.
Summary Use of a so-called deductive method in syntaxonomic classification of roadside plant communities in NE Bohemia.The present paper explains the so-called deductive method of syntaxonomic classification of plant communities, derived from the system of syntaxa of higher rank of the Braun-Blanquet approach. This method enables the synthesis of vegetations units of the varied anthropogenic plant communities in the man-made landscape, and their arrangement within the existing system, without changing the classification and determination criteria of both the higher and lower syntaxa in this system. Basic principles of this method have been outlined earlier by Kopecký & Hejný (1971, 1973, 1974) and Kopecký (1976). Following the newly obtained data and experience, this paper brings further details and more precise explanation of the method. Recently, the deductive method has been applied to the classification of turf communities which spontaneously develop along the roads in NE Bohemia. In order to illustrate the principles of the method, selected relevés of basal communities withAlopecurus pratensis (Table 1), and respective communities derived from these basal communities (Table 2) are presented. A complete set of vegetation relevés of all other roadside communities will be published elsewhere (Kopecký 1978).
Die wissenschaftlichen Pflanzennamen sind nach Rothmaler et al. (1966) angeführt. 相似文献
63.
64.
65.
A study was made of the changes in the content of essential oil and its components (farnesene, (-)-α-bisabolol, (-)-α-bisabololoxide
A, (-)-α-bisabololoxide B and spathulenol, α-bisabolonoxide A, chamazulene, cis en-in-dicycloether) and of the number of secretory
canals in the receptacles during the beginning of flowering, full flowering and the termination of flowering of camomile anthodia.
The total content of the essential oil was highest during the beginning of flowering and lowest during its termination. The
proportion of the individual sesquiterpenes in the essential oil underwent changes mostly during the beginning and termination
of flowering. The number of secretory canals in the basal and middle anthodial parts increased during the beginning of flowering
and the full flowering. 相似文献
66.
Sucrose was markedly superior to fructose and glucose in promoting growth of plantlets from immature maize embryos. The elongation
of roots is shown to be more sucrose dependent than that of shoots. On the other hand, the exogenous sucrose was less effective
than fructose as substrate for carbohydrate catabolism and for the synthesis of alcohol-insoluble compounds at the beginning
of embryo cultivation. The absorbed fructose was found to be rapidly converted to sucrose and the level of endogenous sucrose
derived from sugar supplied to the medium was higher in fructosethan in sucrose-fed embryos. The preferential utilization
of fructose over sucrose, however, declined with the progress of germination which may be related to the decrease in proportion
of scutellum in total mass and physiological activity of the embryo. 相似文献
67.
When inducing simultaneously β-galactosidase and tryptophanase in a batch culture either the synthesis of tryptophanase or
of both enzymes is decreased due to an insufficient cAMP concentration. The addition of this nucleotide can overcome this
decrease. In a continuous culture both enzymes are synthesized at the maximum rate, as the amount of cAMP produced during
carbon limitation of growth is probably sufficient for the simultaneous synthesis of both enzymes. In the β-galactosidase
hyperproduction mutant cultivated continuously the level of β-galactosidase markedly decreases when tryptophanase is simultaneously
induced. Also this decrease is caused by cAMP insufficiency and can be overcome by increasing its concentration. cAMP is thus
an important regulatory factor of both enzymes and becomes a limiting factor in their simultaneous synthesis; a competition
for this regulatory compound apparently occurs and probably also a different mutual affinity of the regulatory complex with
the promoter site of the enzyme opérons is involved. 相似文献
68.
Summary LW13K2 cells, a clone of a spontaneously in vitro transformed derivative of embryonic Lewis rat fibroblastic cells, were studied by phase contrast cine-light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ruffles found at the advancing edge of cells grown on glass substrates in vitro form and recede in a period of less than one min if they do not make an attachment of the substrate. If they fail to make an attachment they may form pinocytotic channels near the leading edge as described by Price (1972) and/or collapse, generally backwards, towards the cell body. The spines which appear to reinforce the membranous ruffles are the last structures to disappear, and accumulate in an irregular array behind the ruffling edge; this area is behind that in which pinocytosis occurs. In comparison with the sparse numbers of ribosomes found in the trailing edge, they are present in notable concentrations near the leading, ruffling edge of the cell. No membrane vesicles have been found in or near the ruffling edges at the ruffle-spine concentration zone. 相似文献
69.
The capacity of pollen tubes to utilize exogenous uridine during 8 h of cultivation in shaken suspension in a sugar-mineral
medium was examined by continuous and pulse labelling with3H-uridine. The increase of uptake with increasing concentration of the nucleoside indicated a saturable transport system with
an approximate Km of 9.4 × 10−6 M and 12.5 × 10−6M as determined in 1-h and 6-h cultures, respectively. Maximal uptake took place at the beginning of germination reaching
a rate of about 2 nmol h−1 per 1 mg of dry pollen at 0.1 mM external uridine. The uptake activity decreased with the time of pollen tube growth to less
than one third during the 8-h cultivation period. Moreover, the level of radioactivity taken up initially decreased later
on during continuous cultivation in the presence of3H-uridine. The uptake took place against a concentration difference and the onset and rate of uridine release depended on
its exogenous concentration.
The activity of the nucleoside incorporation into RNA increased during the first 4 h of cultivation, decreasing later on.
The proportion of RNA radioactivity in continuously labelled pollen tubes grew steadily during 6 h and reached 2.5% with respect
to soluble pool at 0.4 μM uridine. The time course of RNA labelling was independent of uridine concentration within the range
of 0.4 μM to 40 μM but this concentration rise resulted in an about fiftyfold increase of the total amount of external uridine
incorporated. 相似文献
70.