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951.
952.
A Comparison of the Genetic Infrastructure of the Ye''Cuana and the Yanomama: A Likelihood Analysis of Genotypic Variation among Populations 总被引:1,自引:1,他引:0 下载免费PDF全文
A general procedure is described for measuring and testing population differences in gametic frequencies. The total dispersion among populations is subdivided in hierarchical fashion. The multiple-locus treatment is simply the sum of the single-locus analyses, provided gametic equilibrium obtains among the loci. In the event that gametic equilibrium does not obtain, correlations among loci need to be dealt with.—The analysis is then used to examine the genetic infrastructure of two Indian tribes from South America, the Ye'cuana (Makiritare) and the Yanomama. From historical evidence, we may identify several "clusters" of villages within each tribe. The demographic and cultural practices affecting village formation and the maintenance of peer integrity are rather different in these tribes, however, and lead us to postulate rather different patterns of genetic variation among villages. Analyses of five codominant two-allele loci, four dominant two-allele loci and two complex loci (with four codominant haplotypes each) demonstrate that Yanomama clusters are more disparate than Ye'cuana clusters, as would have been predicted on sociocultural grounds. 相似文献
953.
Peter Berthold 《Journal of Ornithology》1978,119(3):287-297
Zusammenfassung 1. In der vorliegenden Arbeit wird die Nistplatzwahl der Mönchsgrasmücke im Fichtenwald in SW-Deutschland dargestellt. Grundlage dieser Untersuchung sind 834 Nestkarten, die die ehrenamtlichen und angestellten Mitarbeiter der Vogelwarte Radolfzell im Grasmücken-Programm des Instituts von 1968–1976 sammelten.2. Die Mönchsgrasmücke nistet in SW-Deutschland häufig im Fichtenwald: 22% aller Nester wurden im Fichtenwald oder in Gruppen von Fichten gefunden. Sie brütet in allen Fichtenwald-Typen vom niedrigen Jungwuchs bis zum Hochwald.3. In den verschiedenen Fichtenwald-Typen variiert die durchschnittliche Nesthöhe nur relativ wenig, aber das Substrat, auf dem Nester gebaut werden, stark: Im Jungwuchs wird im grünen Geäst, in höheren Beständen großenteils auch im Dickicht abgestorbener Äste genistet, im Hochwald entweder im Unterwuchs, oder die Nester werden hier im Außenbereich tief herunterhängender Fichtenäste aufgehängt.4. Die Fichte wird von der Mönchsgrasmücke offenbar für relativ frühe Bruten bevorzugt. Mögliche Ursachen dafür, wie z. B. bessere Deckung oder besondere mikroklimatische Bedingungen, sind unbekannt.5. In hohen unterwuchsarmen Mischwäldern ist es oftmals das Nisten in Fichten, das der Mönchsgrasmücke das Erschließen derartiger Lebensräume ermöglicht.6. Die Mönchsgrasmücke ist ein Paradebeispiel für plastische Nistplatzwahl in stark wechselnden Verhältnissen eines Vegetationstyps — des Fichtenwaldes.7. Abschließend werden regionale Unterschiede des Nistens der Mönchsgrasmücke in Fichten kurz erörtert.
24. Mitteilung aus dem Grasmücken-Programm des Instituts. 相似文献
Studies on the breeding biology of warblers: on the choice of nest sites by blackcaps in spruce forests
Summary 1. In the paper the choice of nest sites of the blackcap Sylvia atricapilla in spruce forests in SW-Germany is presented. This investigation is based on 834 nest record cards which have been collected by the amateur and professional coworkers of the Vogelwarte Radolfzell in the warbler program over the period 1968–1976.2. In SW-Germany, the blackcap often nests in spruce forests: 22% of the nests were found in spruce forests or in groups of spruces. The blackcap nests in all types of spruce forests from very small trees to tall forests.3. In the various types of spruce forests the mean nest heights show only relatively little variation compared with that of the different nest bearing substrata: in small trees the nests are placed in green branches, in higher trees to a great extent also in the thickets of dried up branches, in tall forests either in the underwood or in spruce branches hanging down near to the ground.4. Obviously, in the blackcap the spruce is a preferred nest site for relatively early broods. Whether, for instance, covering or special microclimatic conditions might be reasons for this is open.5. In tall mixed forests without underwood it is often the nesting in spruce trees which enables the blackcap to settle in woods such as these.6. The blackcap is a good example for adaptive choices of nest sites in varying conditions of one type of vegetation as the spruce forest.7. Finally, regional differences of blackcaps' nesting in spruces are shown.
24. Mitteilung aus dem Grasmücken-Programm des Instituts. 相似文献
954.
Summary The biochemical basis of suppression of a temperature-sensitive alanyl-tRNA synthetase (alaS) mutation by mutational alterations of the ribosome has been investigated. Measurement of the polyU-dependent polyphenylalanine synthesis showed that ribosomes from the suppressor strains are less active than ribosomes from the unsuppressed aminoacyl-tRNA synthetase mutant. In this system no increased translational ambiguity could be detected for the suppressor ribosomes. This fact and also the findings that the ram-1 mutation is not able to suppress the aminoacyl-tRNA synthetase mutation and that presence of the suppressor allele is not accompanied by a measureably improved alanyl-tRNA synthetase activity argue against the possibility that suppression might be due to increased translational misreading rates of the alanyl-tRNA synthetase mRNA.It has been further found that partial suppression of temperature sensitive growth of the alaS mutation can be achieved by independent ribosomal mutations leading to reduced growth rates because of a mutation to antibiotic resistance. Addition of low concentrations of a variety of antibiotics acting at the ribosomal level can also partially revert the temperature-sensitive phenotype of the alaS mutant. Although the possibility cannot be excluded that suppression is due to the stabilisation or activation of the mutant enzyme by some indirect effect of the suppressor ribosomal mutations, the following working hypothesis is favoured at the moment: It is assumed that limitation of the aminoacyl-tRNA synthetase activity in a certain range of the restrictive temperature causes growth inhibition by the premature termination of polypeptide synthesis at the ribosome or by the unbalanced synthesis of the individual cellular proteins under this condition. The mechanism of suppression by ribosomal mutations is proposed to consist of the release of this growth inhibition by the reduction of the rate of polypeptide synthesis, which would keep amino acid incorporation from exceeding the slow charging of tRNA and thus exhausting the pool of charged tRNA. In the suppressor strains, therefore, growth at the semi-restrictive temperature is no longer limited by the aminoacylation of tRNA but by the translational process at the mutated ribosome. This influence of the ribosomal mutation on the speed of translation could be directly or indirectly coupled with an effect on translational fidelity resulting in the prevention of the binding of uncharged or non-cognate charged tRNA or in the tighter binding of peptidyl-tRNA when cognate aminoacyl-tRNA is limiting. 相似文献
955.
Friedrich Schmidt Jürgen Besemer Peter Starlinger 《Molecular & general genetics : MGG》1976,145(2):145-154
Summary DNA of the IS-elements IS1 and IS2 was prepared by digestion of appropriate heteroduplex molecules with endonuclease S1, followed by sucrose gradient centrifugation or gel electrophoresis. The material obtained is homogeneous with regard to size. The length of IS1 DNA is 820±65 nucleotides, the length of IS2 DNA is 1.350±70 nucleotides. IS1 DNA is not cleaved by the restriction endonucleases Eco R1, Hind II or Hind III. IS2 DNA is cleaved once by each of the two latter enzymes. The buoyant density determined by equilibrium centrifugation of Hg-complexes in Cs2SO4 corresponds to a GC content of approximately 50%. Labelling with polynucleotide kinase indicates that both IS DNA's have a guanosyl residue at both of their 5-termini. 相似文献
956.
Helmut Ponta Karl-Heinz Altendorf Manfred Schweiger Monica Hirsch-Kaufmann Mei-Li Pfennig-Yeh Peter Herrlich 《Molecular & general genetics : MGG》1976,149(2):145-150
Summary Infection of E. coli with the viruses T7 or T3 leads to a dramatic efflux of potassium ions. This ion efflux is caused by the virus particle since no concomitant protein synthesis is required. T7 mutants carrying deletions in the M-gene (Schweiger et al., 1975), however, yield virus particles disturbed in the ion release. 相似文献
957.
Summary SummaryYeast cultures progressing from the exponential to the stationary phase of growth showed changes in cell sensitivity to physical agents such as UV light, heat shock at 52° C and the chemical mutagens ethyl methane sulphonate, nitrous acid and mitomycin C.Exponential phase cells showed maximum resistance to UV light and minimum resistance to heat shock and the three chemicals. The increased resistance of exponential phase cells to UV light was shown to be dependent upon the functional integrity of the RAD
50 gene.Treatment of growing yeast cultures with radioactively labelled ethyl methane sulphonate indicated the preferential uptake of radioactivity during the sensitive exponential stage of growth. The results indicated that the differential uptake of the chemical mutagens was responsible for at least a fraction of the variations in cell sensitivity observed in yeast cultures at different phases of growth. 相似文献
958.
959.
960.
RNA metabolism was studied in apices of Pharbitis nil duringand after floral induction. In continuous light 3H-uridine accumulatedin RNA at a constant rate over an 18 hr period. In darkness,however, the rate of accumulation of label into RNA was constantuntil the 10th hour at which time a rapid burst of accumulationoccurred, peaking at the 14th hour of darkness and followedby a net loss of label. The RNA involved in this burst is probablymRNA due to its size and poly(A) content. This phenomenon doesnot seem to be associated with floral induction, since the siteof perception is the apex, and it also occurs under conditionswhere floral initiation is inhibited by a brief light interruptionof the dark period. Immediately after floral induction by a16-hr dark period the rate of RNA synthesis was suppressed about14%. This suppression lasts for about 12 hr and was followedby a twofold increase in the rate of RNA synthesis, comparedto non-induced apices, at 64 hr after the beginning of the inductivedark period. These post-induction changes were found to occurin all RNA fractions.
1Present address: Department of Radiation Biology and Biophysics,University of Rochester School of Medicine and Dentistry, Rochester,N.Y. 14642, U.S.A. (Received March 15, 1976; ) 相似文献