Showing papers by "University of Seville published in 1975"
TL;DR: The genetic relationship between germspores and parental mycelia has been investigated in crosses involving multiply-marked heterokaryons and in simple difactor crosses and it is concluded that for each zygospore the number of different diploid nuclei undergoing meiosis is often more than one, but generally not more than two.
Abstract: The genetic relationship between germspores and parental mycelia has been investigated in crosses involving multiply-marked heterokaryons and in simple difactor crosses.It is concluded that for each zygospore the number of different diploid nuclei undergoing meiosis is often more than one, but generally not more than two. The meiotic products divide to produce the nuclei in the usually uninucleate germspore primordia and then continue dividing to produce germspores. Unmated nuclei do not pass directly from parents to progeny.Each germsporangium contains differing numbers of viable germspores, with an average of about 7000; different genotypes are represented by varied numbers of germspores and often expected genotypes are missing. When the results of several germsporangia are added together or germspore stocks from many germsporangia are analysed, reciprocal genotypes appear in equal numbers and reliable recombination frequencies may be calculated.
48 citations
TL;DR: It is concluded that nitrosoguanidine inhibits DNA replication in a small fraction of the population and that mutations are induced in that same fraction.
Abstract: N-Methyl-N'-nitro-N-nitrosoguanidine (nitrosoguanidine) causes an unexpectedly high frequency of closely linked double mutants because of its specificity for chromosome regions in replication. Low nitrosoguanidine concentrations (I mug/ml) in liquid cultures allow replications at the normal rate and are mutagenic. It was expected that mutations would be spread over the chromosome as it replicated, but a high frequency of closely linked double mutants was found. If a thymine auxotroph is grown in the presence of 5-bromodeoxyuridine (BUdR) and nitrosoguanidine, then exposed to 313-nm radiation (which destroys BUdR-substituted DNA), the mutation frequency is much higher among survivors than among non-irradiated cells. It is concluded that nitrosoguanidine inhibits DNA replication in a small fraction of the population and that mutations are induced in that same fraction. Nitrosoguanidine treatment leads to a high frequency of closely linked double mutants under all known conditions.
37 citations
TL;DR: In Chlamydomonas reinhardii the reduction of nitrate to ammonia occurs in two independent enzymatic steps: the two-electrons reduction ofNitrate to nitrite catalyzed by NADH-nitrate reductase, and, the six-electron reduction of Nitrite to ammonia catalyzing by ferredoxin-nitrite reduct enzyme.
Abstract: In Chlamydomonas reinhardii the reduction of nitrate to ammonia occurs in two independent enzymatic steps: 1. the two-electrons reduction of nitrate to nitrite catalyzed by NADH-nitrate reductase, and, 2. the six-electrons reduction of nitrite to ammonia catalyzed by ferredoxin-nitrite reductase. Both enzymes have been purified and characterized, and some of their properties have been studied.
34 citations
TL;DR: The results corroborate Biondi's report of 1910, which described a group of neuroblasts that detaches itself from the primordial oculomotor column approaches the midline, intercrosses there with the cells coming from the other side, and arrives finally at the contralateral complex, where it differentiates as the ventromedial subnucleus.
34 citations
26 citations
TL;DR: In this paper, a method was developed to allow kinetic analysis of the Prout and Tompkins mechanism of solid decomposition reactions using a single TG diagram obtained in a linear heating program.
20 citations
TL;DR: In this paper, the analytical possibilities of the 4-phenyl-3-thiosemicarbazone or biacetylmonoxime were examined and compared with those of the thiose-micarazone of BiacetylMonoxime.
18 citations
TL;DR: Rodenas et al. as discussed by the authors used factor analysis of pairwise comparisons of large dam pictures to study preference pattern and found that the classical group is related to the humanized end of the natural/humanized polarity and shows some negative interdependence with the baroque group.
16 citations
TL;DR: Sulfhydryl-group reagents inactive the nitrate reductase complex from Spinacea oleracea and support the postulated existence of a binding site for pyridine nucleotides implicated in NADH-inactivation and different from the diaphorase catalytic site.
14 citations
TL;DR: It has been shown that reduced ferredoxin from this nitrogen-fixing aerobe is an electron donor for the enzymatic conversion of nitrate to nitrite.
13 citations
TL;DR: The roles of molybdenum and iron in the enzymes of the assimilatory nitrate-reducing system from Azotobacter chroococcum have been investigated and the cellular level of nitrite reductase activity gradually increased in response to the addition of increasing amounts of iron to the culture medium.
Abstract: The roles of molybdenum and iron in the enzymes of the assimilatory nitrate-reducing system from Azotobacter chroococcum have been investigated. 1. By adding 99 Mo-molybdate to a cell culture of A. chrocococcum with nitrate as the nitrogen source, it has been possible to incroporate the radioactive metal into a purified preparation of the enzyme nitrate reductase. 2. When 185 W-tungstate was supplied to a culture medium lacking added molybdate, a 185 W-labelled nitrate reductase preparation with negligible activity could be obtained. This in vivo incorporation of tungsten was competitively hindered by molybdenum. 3. The cellular level of nitrite reductase activity gradually increased in response to the addition of increasing amounts of iron to the culture medium. Under the same conditions, of the level of nitrate reductase activity was not affected.
TL;DR: In this article, the excitation table of a general P-valued JK-type multistable is developed, which does not depend on the number of levels of the logic to be used.
Abstract: The excitation table of a general P-valued JK-type multistable is developed. This table does not depend on the number of levels of the logic to be used.
Journal Article•
Journal Article•
Journal Article•
TL;DR: In this article, the linearized master evolution equations satisfied by the vacuum and the correlations are derived for inhomogeneous systems and the structure of the introduced operators is discussed, and the evolution operator in the correlation-patterns representation is studied in the linear approximation.
Abstract: The evolution operator in the correlation-patterns representation is studied in the linear approximation. The linearized master evolution equations satisfied by the vacuum and the correlations are derived. The equations are applicable to inhomogeneous systems. The structure of the introduced operators is discussed.
TL;DR: In this article, the absorption spectra of the nickel and cobalt (II) complexes of 3-hydroxypicolinealdehyde azine are sufficiently different to permit the simultaneous spectrophotometric determination of both ions when the absorbances are measured at 480 nm and 540 nm.
Journal Article•
01 Jan 1975
TL;DR: In this paper, the principal component analysis of the total coincidence matrix (rotated solutions) and the analysis of correspondences are the most relevant for studies of descriptive ecology, and some properties and applications of different factor analysis techniques of qualitative data are discussed.
Abstract: In this work some properties and applications of different factor analysis techniques of qualitative data are discussed. Using an artiflcially generated set of data we show that the principal component analysis of the total coincidence matrix (rotated Solutions) and the analysis of correspondences are the most relevant for studies of descriptive ecology.