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41.
Escherichia coli and Bacillus megaterium rendered permeable to ribonucleoside triphosphates by toluene treatment retain the capacity to synthesize discrete ribonucleic acid species. 相似文献
42.
Proteolytic processing in the biosynthesis of insulin and other proteins 总被引:41,自引:0,他引:41
43.
44.
45.
Purification of myeloperoxidases from the bone marrow of the guinea pig 总被引:22,自引:0,他引:22
46.
Patterns of (14) CO(2) , assimilate movement in Vicia jaba plants having 7 nodes were studied. Bidirectional translocation occurred throughout most of the stem length when tracer was applied to leaves of various ages. To determine whether this bidirectional translocation occurs within single sieve tubes, a O.1 % solution of the fluorescent dye K-fluorescein was applied to a lightly scraped area on the stem in the middle of a young internode. After one hour the dye was present short distances above and below the treated area. Free-hand sections of the internode showed the dye to be localized in the traces of the larger leaves below tbe treated area and in the traces of the younger leaves above the treated area. The dye was never present in the same bundle both above and below the treated area, indicating that each bundle and sieve tube translocated the dye in only one direction. These results were confirmed using Phaseolus vulgaris, Vinca rosea, and Pelargonium hortum. A similar study in which petioles of young Ecballium elaterium leaves were treated showed that usually the phloem of one bundle translocated the dye in only one direction but in some cases the external phloem of the bicollateral bundles carried the dye toward the stem while the internal phloem carried the dye toward the blade. When longer time intervals were used in all these experiments, the dye sometimes appeared in the same phloem areas both above and below the treated area. This is explained by a lateral transfer of tracer within the phloem, either through secondary phloem or through bundle anastomoses at the nodes. 相似文献
47.
The deoxyribonucleic acid homologies of Mycoplasma laidlawii type A and type B, M. pulmonis (#47 and #63), and M. hominis were determined by membrane methodology. The homology data revealed a difference in genome size between M. laidlawii type A and type B. This difference also held with stringent conditions of annealing (high temperature). Little or negligible homology was shown to exist between the M. laidlawii strains type A and type B and M. pulmonis strains 47 and 63 and M. hominis. M. hominis showed less than 10% homology to the M. pulmonis and M. laidlawii strains. Neither of the M. laidlawii strains showed more than 2% annealing to the M. pulmonis strains. Reaction rate studies are suggested as a means of demonstrating the phylogenetic relationship between the Mycoplasma and other microorganisms. 相似文献
48.
Professor Peter A. Peterson Professor C. R. Weber 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1969,39(4):156-162
Summary Investigation of a variegated condition in the soybean variety Lincoln indicates instability at the Y locus. Leaf sectors of chlorophyll-less yellow tissue occur in distinct heritable patterns; some leaves have small flecks of yellow tissue (late occurring mutations) and others possess large areas or whole leaflets (early occurring mutations).There is evidence that this allele, Y
18
m
, mutates to the wild type, Y, which is green and stable and to the recessive, y, which is yellow and lethal in the seedling condition. (With an increase in the amount of yellow tissue there is an increase in the frequency of lethals.) However, changes from one type to the other are observed, and patterns of variegation representing different states of the instability are described. These depend upon the time and frequency of mutation events.Evidence is presented to support the hypothesis that this instability is controlled by a factor that resides at the locus. Such a factor governs the timing of the mutation events and is related to similar elements in maize, which are part of specific mutable systems. Control of variegation of the Y
18
m
locus is compared with the models proposed for the cases of instability in maize.
Joint contribution from the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa (Projects 1335 und 1179) as Journal Paper No. 5635.
Former Agronomist, Crops Research Division, ARS, USDA, and Professor Iowa State University; now Research Director, Peterson Seed Company. 相似文献
Zusammenfassung Die Untersuchung eines variegaten Zustandes bei der Sojabohnensorte Lincoln führte zum Nachweis einer Instabilität des Y-Locus. Blattsektoren mit chlorophyllfreiem gelbem Gewebe traten in bestimmten erblichen Mustern auf. Einige Blätter wiesen kleine Flecken gelben Gewebes auf (spät eingetretene Mutationen), während andere große Flächen oder vollständig gelbe Blättchen besaßen (früh eingetretene Mutationen).Es gibt Beweise dafür, daß das entsprechende Allel Y 18 m sowohl zum stabilen Wildtypallel Y, mit grünem Phänotyp, als auch zum rezessiv gelben y, das im Sämlingsstadium letal wirkt, mutiert. (Eine Zunahme der Menge gelben Gewebes ist mit einer Zunahme der Letalfrequenz verbunden.) Umwandlungen eines Typs zu einem anderen werden beobachtet und Variegationsmuster beschrieben, die unterschiedliche Stadien der Instabilität verkörpern. Diese hängen von dem Zeitpunkt und der Frequenz der Mutationsereignisse ab.Es werden Beweise vorgelegt, die die Hypothese stützen, daß diese Instabilität durch einen Faktor kontrolliert wird, der sich am Locus befindet. Ein Faktor dieser Art kontrolliert das zeitliche Auftreten der Mutationsereignisse. Er ist mit ähnlichen Elementen des Maises verwandt, die Teile eines spezifisch mutablen Systems sind. Die Kontrolle der Variegation durch den Y 18 m -Locus wird mit den Modellen verglichen, die für die Fälle der Instabilität beim Mais vorgeschlagen wurden.
Joint contribution from the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa (Projects 1335 und 1179) as Journal Paper No. 5635.
Former Agronomist, Crops Research Division, ARS, USDA, and Professor Iowa State University; now Research Director, Peterson Seed Company. 相似文献
49.
An evaluation of the respiratory capacity of human spermatozoa 总被引:1,自引:0,他引:1
50.
The incorporation of 14C-leucine and 14C-amino acid mixture into protein in unfertilized eggs and developing embryos of the brown alga Fucus vesiculosus L. was studied. Bacterial contamination was initially a problem, but it was found that the addition of 40 μg/ml chloramphenicol to the incubation medium would inhibit bacterial protein synthesis without affecting early development of the Fucus embryos. The kinetics of uptake and incorporation of 14C-leucine into the trichloroacetic acid-soluble and -insoluble fractions indicated that the exogenous precursor did not equilibrate with the main soluble leucine pool before incorporation into protein. Uptake and incorporation of leucine by embryos 90 to 175 minutes old were proportional to exogenous leucine concentration over the range 5 × 10−6 m to 5 × 10−3 m. Unfertilized eggs will incorporate 14C-leucine into protein. The rate of this incorporation increases dramatically in newly fertilized eggs with a maximum rate at 3.5 hours, a period of cell wall formation and increasing metabolic rates. Thereafter, the rate of incorporation declines until approximately 15 to 17 hours when it increases again concurrently with the onset of rhizoid initiation and cell division. 相似文献