THE GENOMIC ORIGIN OF THE UNPAIRED CHROMOSOMES IN TRITICALE

1976 ◽  
Vol 18 (4) ◽  
pp. 687-700 ◽  
Author(s):  
J. B. Thomas ◽  
P. J. Kaltsikes
Keyword(s):  
Meiotic Metaphase ◽  
The Other ◽  
Differential Staining ◽  
Hexaploid Triticale ◽  
Genome Chromosome ◽  
Other Hand ◽  
Telocentric Chromosomes ◽  
Telomeric Heterochromatin ◽  
Triticosecale Wittmack ◽  
Terminal Chiasmata

Differential staining of telomeric rye heterochromatin and telocentric chromosomes were used to identify chromosomes which were unpaired at first meiotic metaphase of hexaploid triticale (× Triticosecale Wittmack). Both approaches showed that it was the rye chromosomes which were seen as univalents. Differences in the rate of pairing from triticale to triticale were mostly explained by variation in the pairing of the rye genome. Within the rye genome, chromosome arms with telomeric heterochromatin showed pairing rates much lower than chromosome arms lacking heterochromatin. Wheat telocentrics and heterochromatin-free rye telocentrics which showed intermediate levels of pairing failure (65-90%), had mostly terminal chiasmata. On the other hand rye telocentrics with large heterochromatin bands on the telomeres had mostly nonterminal chiasmata and very low pairing (5-35%). It is concluded that the presence of heterochromatin on certain telomeres of rye chromosomes blocks the formation of terminal chiasmata and this results in desynapsis and univalents at MI.

Effect of chromosome 1B, chromosome 6B, and low temperature on the frequency of chromosome pairing at first meiotic metaphase in hexaploid triticale

1983 ◽  
Vol 25 (3) ◽  
pp. 278-282
Author(s):  
Julian B. Thomas ◽  
P. J. Kaltsikes ◽  
S. Shigenaga
Keyword(s):  
Low Temperature ◽  
Common Wheat ◽  
Chromosome Pairing ◽  
Meiotic Metaphase ◽  
The Other ◽  
Hexaploid Triticale ◽  
Other Hand

Chromosome 1B in 'Rosner' and chromosome 6B in line 125 both reduced the frequency with which chromosomes were paired at first meiotic metaphase of hexaploid triticale. On the other hand, chromosome 6B in 'Rosner' and chromosomes 1B and 6B in line 110 had no such effect. The 1B pairing suppressor in 'Rosner' was located on the short arm of the chromosome (1Bs). Between 10 and 30 °C, pairing frequency was quite stable in 'Rosner' triticale in comparison with common wheat, although the level was consistently lower in the triticale. Some reduction of pairing frequency was noted at 10 °C in 'Rosner'. This effect of low temperature did not interact with 1B dosage to cause a disproportionate decrease in pairing frequency when plants with high 1B dosage were grown at 10 °C.

THE EFFECT OF TELOMERIC HETEROCHROMATIN ON CHROMOSOME PAIRING OF HEXAPLOID TRITICALE

1977 ◽  
Vol 19 (3) ◽  
pp. 543-548 ◽  
Author(s):  
D. G. Roupakias ◽  
P. J. Kaltsikes
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Metaphase ◽  
Single Plant ◽  
Hexaploid Triticale ◽  
Telomeric Heterochromatin ◽  
Triticosecale Wittmack

Plants carrying (++) or lacking (−−) most of the telomeric heterochromatic band on the short arm of chromosome 6R(6RS) were isolated from a single plant progeny of Rosner triticale (× Triticosecale Wittmack) heterozygous for this band. Chromosome pairing at first meiotic metaphase was significantly higher in −− than in ++ or +− plants. The changes in chromosome pairing were likely due to the 6RS telomeric heterochromatin which affected the pairing not only of the arm carrying it but of other chromosomes as well.

Introduction of the D-genome chromosomes from bread wheat into hexaploid triticale with a complete rye genome

Genome ◽  
1987 ◽  
Vol 29 (3) ◽  
pp. 425-430 ◽  
Author(s):  
A. J. Lukaszewski ◽  
B. Apolinarska ◽  
J. P. Gustafson
Keyword(s):  
Key Words ◽  
Bread Wheat ◽  
Hexaploid Triticale ◽  
Genome Chromosome ◽  
D Genome ◽  
Homozygous Condition ◽  
C Banding ◽  
B Genome ◽  
Chromosome Substitutions ◽  
Triticosecale Wittmack

Hexaploid triticale (× Triticosecale Wittmack) lines selected from the progeny of octoploid × tetraploid triticale hybrids were karyotyped using C-banding. The number of D-genome chromosome pairs substituted for A- and (or) B-genome chromosomes ranged from 0 to 4, averaging 2.1 substitutions per line. Every D-genome chromosome was present in at least 1 of the 70 lines analyzed. The most frequent were chromosomes 3D and 6D, followed by 1D. Of the 14 possible substitutions, 12 were present in the homozygous condition, 1 (4D/4B) was still segregating, and 6D/6B was absent. With the exception of one 1D/1R substitution and one 7RS/4DS translocation, all lines had a complete rye genome. Key words: triticale, chromosome substitutions, D genome.

INFLUENCE OF SOURCE OF WHEAT CYTOPLASM ON THE SYNTHESIS AND PLANT CHARACTERISTICS OF HEXAPLOID TRITICALE

1974 ◽  
Vol 16 (2) ◽  
pp. 333-340 ◽  
Author(s):  
S. L. K. Hsam ◽  
E. N. Larter
Keyword(s):  
Reproductive Behavior ◽  
Female Parent ◽  
Triticum Aestivum L ◽  
The Other ◽  
Agronomic Performance ◽  
Hexaploid Triticale ◽  
Embryo Survival ◽  
Plant Characteristics ◽  
Triticosecale Wittmack

Reciprocal F1 triticale hybrids (× Triticosecale Wittmack) produced from crosses between primary 6x amphiploids (C1) were synthesized that differed only in their source of cytoplasm. One member of each reciprocal pair possessed hexaploid (6x) wheat cytoplasm (Triticum aestivum L. em Thell), the other, tetraploid (4x) wheat cytoplasm (T. turgidum L.). Comparisons of agronomic and reproductive behavior were made between members of reciprocal F1 pairs. Initial embryo development, embryo survival in vitro, and survival of F1 wheat-rye hybrids were 10, 105, and 127% higher respectively when the female parent possessed 6x as compared with 4x wheat cytoplasm. Similarly, F1 amphiploids with 6x cytoplasm were 3.0% taller and developed 25.0% more fertile tillers than their genetically identical counterparts with 4x cytoplasm. Spike morphology and floret number were not found to be influenced by source of cytoplasm. As current triticale procedures require the synthesis of new wheat-rye amphiploids for the introduction of genetic variability, it is suggested that the utilization of 6x wheat cytoplasm would enhance such a program as well as improve the agronomic performance of triticales so synthesized.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

Don’t Put Me in This Group

2019 ◽  
Vol 50 (2) ◽  
pp. 80-93
Author(s):  
Jort de Vreeze ◽  
Christina Matschke
Keyword(s):  
Positive Emotions ◽  
Negative Emotions ◽  
Negative Information ◽  
The Self ◽  
The Other ◽  
Other Hand ◽  
Group Memberships

Abstract. Not all group memberships are self-chosen. The current research examines whether assignments to non-preferred groups influence our relationship with the group and our preference for information about the ingroup. It was expected and found that, when people are assigned to non-preferred groups, they perceive the group as different to the self, experience negative emotions about the assignment and in turn disidentify with the group. On the other hand, when people are assigned to preferred groups, they perceive the group as similar to the self, experience positive emotions about the assignment and in turn identify with the group. Finally, disidentification increases a preference for negative information about the ingroup.

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