The cytology of hybrids between Hordeum vulgare and H. bulbosum revisited

Genome ◽  
1988 ◽  
Vol 30 (4) ◽  
pp. 486-494 ◽  
Author(s):  
Xu Jie ◽  
J. W. Snape
Keyword(s):  
Hordeum Vulgare ◽  
High Frequency ◽  
Interspecific Hybrids ◽  
Somatic Chromosome ◽  
Banding Technique ◽  
Chromosome 6 ◽  
Hordeum Bulbosum ◽  
Chromosome Counts ◽  
Low Frequencies ◽  
C Banding

Diploid and triploid interspecific hybrids were produced from crosses between four Hordeum vulgare varieties and two diploid and two tetraploid Hordeum bulbosum genotypes. These were studied cytologically using a C-banding technique as well as with conventional staining procedures. C-banding of mitotic preparations of the hybrids enabled all H. vulgare chromosomes to be identified individually, although only the satellited chromosome of H. bulbosum could be distinguished from the others of this genome. Most diploid hybrids had stable somatic chromosome constitutions (2n = 14), although 4 out of 39 plants had a mosaic constitution. Chromosome counts of triploid hybrids, however, revealed that about 40% of plants had a mosaic somatic constitution ranging from 7–22 chromosomes per cell, although 21-chromosome cells were at the highest frequency. Studies of meiosis in diploid hybrids showed that the frequency of pairing between H. vulgare and H. bulbosum chromosomes varied between different cross combinations and appeared to be mainly under the control of the H. bulbosum genome. C-banding revealed that H. vulgare chromosome 6 paired with the satellited chromosome of H. bulbosum. However, this latter chromosome was also absent in the majority of aneuploid cells and appeared to be the first to be eliminated. Meiosis in triploid hybrids was characterized by the presence of univalents, bivalents, and trivalents and, infrequently, higher order associations. Bivalents were formed mainly from pairing between H. bulbosum chromosomes alone, although trivalents were formed from pairing between two H. bulbosum and one H. vulgare chromosomes. All univalents, in cells that contained less than seven, were H. vulgare chromosomes. Overall, these results indicate that a high frequency of homoeologous allosyndesis can occur between the chromosomes of these two species, but it does depend on the H. bulbosum genotype used. It should be possible to introgress genes into H. vulgare through the use of H. bulbosum genotypes that have low frequencies of elimination and high chromosome pairing.Key words: Hordeum vulgare, H. bulbosum, C-banding, chromosome pairing.

Identification of all chromosome arms and their involvement in meiotic homoeologous associations at metaphase I in 2 Hordeum vulgare L. × Hordeum bulbosum L. hybrids

Genome ◽  
2006 ◽  
Vol 49 (1) ◽  
pp. 73-78 ◽  
Author(s):  
R Pickering ◽  
S Klatte ◽  
R C Butler
Keyword(s):  
In Situ Hybridization ◽  
Hordeum Vulgare ◽  
Fluorescence In Situ Hybridization ◽  
Interspecific Hybrids ◽  
Association Studies ◽  
Hordeum Bulbosum ◽  
Hordeum Vulgare L ◽  
Chromosome Addition ◽  
Chromosome Associations

We have identified all Hordeum bulbosum chromosomes in 2 diploid Hordeum vulgare × Hordeum bulbosum hybrids using suitable probes and fluorescence in situ hybridization. Using the parental idiograms allowed us to carry out a full analysis of chromosome associations among all chromosome arms in the hybrids. Association frequencies were generally lower for the short arms than for the long arms. There were also significant differences among the chromosome arms in association frequencies, partly correlated with the absolute length of the chromosome arm, as well as with the frequency of recombinant lines, which were recovered from partially fertile interspecific hybrids. The H. bulbosum idiogram will be useful for further chromosome association studies and will enable the identification of H. bulbosum chromosomes involved in chromosome addition or substitution lines.Key words: Hordeum vulgare, Hordeum bulbosum, interspecific hybrids, chromosome associations, meiosis, fluorescence in situ hybridization.

Chromosome instability in somaclones of a Triticum crassum × Hordeum vulgare hybrid

1986 ◽  
Vol 28 (4) ◽  
pp. 618-623 ◽  
Author(s):  
George Fedak ◽  
John Grainger
Keyword(s):  
Hordeum Vulgare ◽  
Chromosome Number ◽  
High Frequency ◽  
Chromosome Instability ◽  
Dichlorophenoxyacetic Acid ◽  
Meiotic Pairing ◽  
Immature Inflorescence ◽  
Low Frequencies ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Subsequent Regeneration

Immature inflorescence culture and subsequent plant regeneration was practiced for four successive cycles using a Triticum crassum × Hordeum vulgare hybrid cultured on Kao's medium supplemented with 2,4-dichlorophenoxyacetic acid (5 mg/mL). In one line, chromosomal mixoploidy was observed among both mitotic and meiotic cells. Variation in chromosome number of 20 to 98 was observed in mitotic and 14 to 68 among meiocytes in the first cycle regenerants. The range in chromosome number decreased in subsequent regeneration cycles. Fragmented chromosomes were observed at low frequencies in both groups of cells. The high frequency of univalents at meiosis was attributed to possible elimination of chromosomes carrying meiotic pairing control genes.Key words: somaclonal variation, hybrids (intergeneric), tissue culture, chromosomal mixoploidy.

scholarly journals Earless toads sense low frequencies but miss the high notes

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171670 ◽  
Author(s):  
Molly C. Womack ◽  
Jakob Christensen-Dalsgaard ◽  
Luis A. Coloma ◽  
Juan C. Chaparro ◽  
Kim L. Hoke
Keyword(s):  
High Frequency ◽  
Species Differences ◽  
Low Frequency ◽  
Auditory Brainstem ◽  
Low Frequencies ◽  
Hearing Sensitivity ◽  
Sensory Pathways ◽  
Airborne Sound ◽  
Vibrational Sensitivity ◽  
Species Specific

Sensory losses or reductions are frequently attributed to relaxed selection. However, anuran species have lost tympanic middle ears many times, despite anurans' use of acoustic communication and the benefit of middle ears for hearing airborne sound. Here we determine whether pre-existing alternative sensory pathways enable anurans lacking tympanic middle ears (termed earless anurans) to hear airborne sound as well as eared species or to better sense vibrations in the environment. We used auditory brainstem recordings to compare hearing and vibrational sensitivity among 10 species (six eared, four earless) within the Neotropical true toad family (Bufonidae). We found that species lacking middle ears are less sensitive to high-frequency sounds, however, low-frequency hearing and vibrational sensitivity are equivalent between eared and earless species. Furthermore, extratympanic hearing sensitivity varies among earless species, highlighting potential species differences in extratympanic hearing mechanisms. We argue that ancestral bufonids may have sufficient extratympanic hearing and vibrational sensitivity such that earless lineages tolerated the loss of high frequency hearing sensitivity by adopting species-specific behavioural strategies to detect conspecifics, predators and prey.

scholarly journals Importance of the Secondary Genepool in Barley Genetics and Breeding. I. Cytogenetics and Molecular Analysis

2011 ◽  
Vol 40 (No. 3) ◽  
pp. 73-78 ◽  
Author(s):  
R. Pickering ◽  
A. Johnston P ◽  
B. Ruge
Keyword(s):  
Hordeum Vulgare ◽  
Plant Breeding ◽  
Molecular Analysis ◽  
Hordeum Bulbosum ◽  
Hordeum Vulgare L ◽  
Cultivated Barley

There have been no plant breeding developments using species from the tertiary genepool of cultivated barley for breeding or genetics since the VIII<sup>th</sup> International Barley Genetics Symposium in 2000. Hence, the first part of this review describes progress since 2000 in developing and characterising recombinant lines derived from hybridisations between the sole species in the secondary genepool, Hordeum bulbosum L., and cultivated barley, Hordeum vulgare L. The topics discussed in part I are cytogenetics and molecular analysis of recombinant lines. &nbsp;

The Effect of Homoeologous Meiotic Pairing in Tetraploid Hordeum bulbosum L. × H. vulgare L. Hybrids on Alien Introgressions in Offspring

2016 ◽  
Vol 150 (2) ◽  
pp. 139-149 ◽  
Author(s):  
Margret Scholz ◽  
Galina Pendinen
Keyword(s):  
Interspecific Hybrids ◽  
In Situ Hybridisation ◽  
Basic Material ◽  
Meiotic Pairing ◽  
Hordeum Bulbosum ◽  
Homoeologous Pairing ◽  
Introgression Breeding ◽  
The Individual ◽  
Pairing Behaviour

The pairing behaviour of the individual chromosome arms of Hordeum vulgare (Hv) with their homoeologous arms of H. bulbosum (Hb) at metaphase I of meiosis in tetraploid Hb × Hv hybrids and the frequencies of recombined Hv chromosome arms in selfed offspring were studied on differentially visualized chromosomes after fluorescent in situ hybridisation. The frequencies of paired Hv-Hb arms in the F2 and F3 hybrids were correlated with the frequencies of recombined Hv chromosomes in progenies. Self-generation of hybrids, the number of Hv and Hb chromosomes, and the number of recombined Hv chromosomes of the hybrids strongly influenced the Hv-Hb pairing frequency in meiosis. Within the offspring of F2 and F3 hybrids both Hv plants and hybrids were detected. In contrast, all progenies of the F4 hybrid were hybrids which exhibited centromere misdivisions. The highest frequencies of homoeologous pairing in hybrids and most recombinants were obtained for the barley chromosome 1HL. Recombinants for 4HL, 5HS, 6HS, and 7HS were rarely found. Meiotic pairing and recombinants involving chromosome 1HS were never observed. The results of this study demonstrate that fertile tetraploid interspecific hybrids with a high intergenomic pairing at meiosis are valuable basic material for introgression breeding in barley.

scholarly journals The Estimation of Hydrometeor Profiles from Wideband Microwave Observations

2000 ◽  
Vol 39 (10) ◽  
pp. 1645-1656 ◽  
Author(s):  
Gail M. Skofronick-Jackson ◽  
James R. Wang
Keyword(s):  
High Frequency ◽  
Cloud Water ◽  
Tropical Ocean ◽  
Low Frequencies ◽  
High Frequencies ◽  
Atmospheric Research ◽  
Brightness Temperatures ◽  
Microphysical Properties ◽  
Ice Microphysics ◽  
Updraft Region

Abstract Profiles of the microphysical properties of clouds and rain cells are essential in many areas of atmospheric research and operational meteorology. To enhance the understanding of the nonlinear and underconstrained relationships between cloud and hydrometeor microphysical profiles and passive microwave brightness temperatures, estimations of cloud profiles for an anvil region, a convective region, and an updraft region of an oceanic squall were performed. The estimations relied on comparisons between radiative transfer calculations of incrementally estimated microphysical profiles and concurrent dual-altitude wideband brightness temperatures from the 22 February 1993 flight during the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment. The wideband observations (10–220 GHz) are necessary for estimating cloud profiles reaching up to 20 km. The low frequencies enhance the rain and cloud water profiles, and the high frequencies are required to detail the higher-altitude ice microphysics. A microphysical profile was estimated for each of the three regions of the storm. Each of the three estimated profiles produced calculated brightness temperatures within ∼10 K of the observations. A majority of the total iterative adjustments were to the estimated profile’s frozen hydrometeor characteristics and were necessary to match the high-frequency calculations with the observations. This requirement indicates a need to validate cloud-resolving models using high frequencies. Some difficulties matching the 37-GHz observation channels on the DC-8 and ER-2 aircraft with the calculations simulated at the two aircraft heights (∼11 km and 20 km, respectively) were noted, and potential causes were presented.

scholarly journals The dual-slope conversion improvement

2014 ◽  
Vol 11 (3) ◽  
pp. 351-363
Author(s):  
Radojle Radetic ◽  
Marijana Pavlov-Kagadejev ◽  
Nikola Milivojevic
Keyword(s):  
High Frequency ◽  
Frequency Noise ◽  
Good Resolution ◽  
Practical Realization ◽  
Digital Conversion ◽  
Low Frequencies ◽  
Analog To Digital ◽  
High Frequency Noise ◽  
Low Input ◽  
Analog To Digital Conversion

The dual-slope ADC (DSADC) is a type of analog-to-digital conversion with low input bandwidths. It is pretty slow, but its ability to reject high-frequency noise and fixed low frequencies such as 50 Hz or 60 Hz makes it useful in noisy industrial environments and applications. It provides very good resolution. For the practical measurements in the Institutes laboratory an instrument is designed and realized. The base DSADC method is used, but improved by multiple conversions to make the measuring more precise and the time shorter. The special attention is paid to the problems occurred in practical realization and the way to overcome them. The paper describes the proposed and applied solutions, functional principles and achieved performances of the realized instrument.

scholarly journals Novel Negative Capacitance and Conductance in All Temperatures and Voltages of Au/CNTs/n-Si/Al at Low and High Frequencies

2021 ◽  
Author(s):  
A. Ashery ◽  
Samia Gad ◽  
A. E.H. Gaballah ◽  
G. M. Turky
Keyword(s):  
Carbon Nanotube ◽  
High Frequency ◽  
Series Resistance ◽  
Negative Capacitance ◽  
Donor Concentration ◽  
Low Frequencies ◽  
High Frequencies ◽  
Depletion Width ◽  
Density Surface ◽  
P Type

Abstract The structure of carbon nanotube CNTs functioning as p-type material deposited over n-type silicon to produce heterojunction of Au/CNTs/n-Si/Al is presented in this study.This work explored the capacitance and conductance at various frequencies, temperatures, and voltages, the novelty here is that negative capacitance and conductance were observed at high frequencies in all temperatures and voltages, whereas capacitance appeared at both high and low frequencies, such as (2x107,1x107,1x102,10) Hz. At high-frequency f = 2x107 Hz, the capacitance raises while the conductance decreases; at all temperatures and voltages, the capacitance and conductance exhibit the same behavior at particular frequencies such as 1x106,1x105,1x104,1x103Hz, however their behavior differs at 2x107,1x107, 1x102 and 10Hz. Investigating the reverse square capacitance with voltage yielded the energy fermi (Ef), density surface of states (Nss), depletion width (Wd), barrier height, series resistance, and donor concentration (Nd)

SKY reveals a high frequency of unbalanced translocations involving chromosome 6 in t(12;21)-positive acute lymphoblastic leukemia

2008 ◽  
Vol 32 (1) ◽  
pp. 39-43 ◽  
Author(s):  
David R. Betts ◽  
Racheli Stanchescu ◽  
Felix K. Niggli ◽  
Ninette Cohen ◽  
Gideon Rechavi ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
High Frequency ◽  
Lymphoblastic Leukemia ◽  
Chromosome 6

Calibration of a Semi-Stochastic Procedure for Simulating High-Frequency Ground Motions

2013 ◽  
Vol 29 (4) ◽  
pp. 1495-1519 ◽  
Author(s):  
Emel Seyhan ◽  
Jonathan P. Stewart ◽  
Robert W. Graves
Keyword(s):  
High Frequency ◽  
Ground Motions ◽  
Random Phase ◽  
Low Frequencies ◽  
Intensity Measures ◽  
Amplitude Spectra ◽  
Random Site ◽  
Broadband Ground Motion Simulation ◽  
Broadband Ground Motion ◽  
Attenuation Bias

Broadband ground motion simulation procedures typically utilize physics-based modeling at low frequencies, coupled with semi-stochastic procedures at high frequencies. The high-frequency procedure considered here combines deterministic Fourier amplitude spectra (dependent on source, path, and site models) with random phase. Previous work showed that high-frequency intensity measures from this simulation methodology attenuate faster with distance and have lower intra-event dispersion than in empirical equations. We address these issues by increasing crustal damping (Q) to reduce distance attenuation bias and by introducing random site-to-site variations to Fourier amplitudes using a lognormal standard deviation ranging from 0.45 for Mw < 7 to zero for Mw 8. Ground motions simulated with the updated parameterization exhibit significantly reduced distance attenuation bias and revised dispersion terms are more compatible with those from empirical models but remain lower at large distances (e.g., > 100 km).

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