The determination of position in crossing-over

1936 ◽  
Vol 33 (2) ◽  
pp. 207-235 ◽  
Author(s):  
K. Mather
Keyword(s):  
Crossing Over

DETERMINATION OF BREAKPOINT POSITIONS IN BARLEY TRANSLOCATIONS BY KARYOTYPE ANALYSIS OF PERMANENT RINGS OF SIX CHROMOSOMES

1974 ◽  
Vol 16 (3) ◽  
pp. 539-548 ◽  
Author(s):  
N. A. Tuleen ◽  
J. H. Gardenhire
Keyword(s):  
Karyotype Analysis ◽  
Chromosome 1 ◽  
Crossing Over ◽  
Differential Segment

Five T1-5 and 10 T1-6 barley translocations were crossed with the translocation T1-7f. Plants in which the T1-5 and T1-6 translocations had been combined with T1-7f due to crossing over in the differential segment were selected in the F2 generation. One of the chromosomes present in plants carrying the translocations in the combined form is made up of parts of the three chromosomes involved in the two translocations, and the segmental arrangement of this tripartite chromosome is determined by the position of the breakpoints in chromosome 1. The karyotypes of these stocks were analyzed and the breakpoints in seven of the translocations were assigned to the same arm and eight to the opposite arm of chromosome 1 relative to the position of the breakpoint in T1-7f.

THE RELATIONSHIP BETWEEN CHIASMATA AND CROSSING OVER IN TRITICUM AESTIVUM

Genetics ◽  
1973 ◽  
Vol 75 (2) ◽  
pp. 231-246
Author(s):  
T K Fu ◽  
E R Sears
Keyword(s):  
Chiasma Frequency ◽  
Rust Resistance ◽  
Genetic Recombination ◽  
Substantial Reduction ◽  
Leaf Rust Resistance ◽  
Crossing Over ◽  
Two Temperatures ◽  
Independent Behavior ◽  
The Relationship

ABSTRACT Telocentrics for the β arm of chromosome 4A and the long arm of 6B were used as cytological markers for the determination of chiasma frequency. In concomitant studies of recombination, terminal segments of rye and T. umbellulatum chromatin carrying Hp (Hairy peduncle) and Lr9 (Leaf-rust resistance), respectively, marked 4A and 6B. Two temperatures, 21° and 32°, were used for both the 4A and 6B experiments.—Only one chiasma was observed in each heteromorphic bivalent. Because there was a substantial reduction in pairing between diakinesis and metaphase I, all determinations of chiasma frequency were made at diakinesis. In the 21° experiments, agreement was good between genetic recombination and cytological prediction on the basis of the partial chiasmatypy hypothesis that each chiasma represents a crossover. At 32° both chiasma frequency and crossing over, but particularly the latter, were strongly reduced. The fewer crossovers than expected are explained in part by stickiness of chromosomes at the high temperature, sometimes resulting in adjacent chromosomes being wrongly scored as having a chiasma, and in part by premetaphase disjunction of some recombined bivalents and subsequent independent behavior of the two resulting univalents.—Male transmission of the 4A telocentric from the heteromorphic bivalent was unusually high: 51% at 21° and 31% at 32°.

The determination of position in crossing-over

1940 ◽  
Vol 39 (2) ◽  
pp. 205-223 ◽  
Author(s):  
K. Mather
Keyword(s):  
Crossing Over

Structural changes of Ag-stained nucleolus organizing regions and nucleoli during meiosis in Allium flavum

1983 ◽  
Vol 25 (5) ◽  
pp. 524-529 ◽  
Author(s):  
Josef Loidl ◽  
Johann Greilhuber
Keyword(s):  
Light Microscopy ◽  
Structural Changes ◽  
Silver Impregnation ◽  
Crossing Over ◽  
Prophase I ◽  
Impregnation Technique ◽  
Chromosome Arm ◽  
Meiotic Cycle

Microsporogenesis of Allium flavum was investigated by light microscopy using a silver impregnation technique. Ag-positive structures were present at the nucleolus organizing regions (NORs) in all stages of the meiotic cycle. During prophase I the nucleoli were found to be composed of a strongly impregnated central and a weakly impregnated peripheral component, probably corresponding to the pars fibrosa and pars granulosa, respectively. A heteromorphism with regard to the presence of a NOR allowed the determination of the crossing-over frequency in the chromosome arm concerned.

scholarly journals The Determination of Position in Crossing-over. II

CYTOLOGIA ◽  
1937 ◽  
Vol FujiiJubilaei (1) ◽  
pp. 514-526 ◽  
Author(s):  
K. Mather
Keyword(s):  
Crossing Over

scholarly journals The detection of linkage in human families. I.–Both heterozygous genotypes indeterminate

1934 ◽  
Vol 114 (789) ◽  
pp. 340-352 ◽  
Keyword(s):  
General Population ◽  
Human Genetics ◽  
Crossing Over ◽  
Human Chromosomes ◽  
Theoretical Possibility ◽  
Growing Body ◽  
Order Of Magnitude

In (1931) Bernstein published a method of analysis for the determination of linkage in a group of families consisting of parents and offspring of known phenotypes. This contribution was a signal event in the progress of human genetics. It disclosed the theoretical possibility of constructing a map of the human chromosomes. Although the practical difficulties which beset such a task are not insignificant, a growing body of information concerning gene substititions with allelomorphic frequencies of the same order of magnitude in the general population encourages the hope that they will be overcome in the course of time. At present the iso agglutinin reaction, the new hetero agglutinins of Landsteiner and Levine (1931), together with the work of Snyder (1932) and Blakeslee (1931) provide the most suitable basis for the determination of linkage. When dominance is complete, three classes of matings yield phenotypic proportions which depend upon the crossing over value.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Sign in / Sign up

Export Citation Format

Share Document