Meiotic events in Oenothera — a non-standard pattern of chromosome behaviour

Genome ◽  
2008 ◽  
Vol 51 (11) ◽  
pp. 952-958 ◽  
Author(s):  
Hieronim Golczyk ◽  
Krystyna Musiał ◽  
Uwe Rauwolf ◽  
Jörg Meurer ◽  
Reinhold G. Herrmann ◽  
...  
Keyword(s):  
Degree Of Polarization ◽  
Chromosome Behaviour ◽  
High Complexity ◽  
Standard Pattern ◽  
Reciprocal Translocations ◽  
Chromosome Configuration ◽  
Long Period ◽  
Translocation Heterozygosity ◽  
High Degree ◽  
Contraction Stage

The genus Oenothera shows an intriguing extent of permanent translocation heterozygosity. Reciprocal translocations of chromosome arms in species or populations result in various kinds of chromosome multivalents in diakinesis. Early meiotic events conditioning such chromosome behaviour are poorly understood. We found a surprising uniformity of the leptotene–diplotene period, regardless of the chromosome configuration at diakinesis (ring of 14, 7 bivalents, mixture of bivalents and multivalents). It appears that the earliest chromosome interactions at Oenothera meiosis are untypical, since they involve pericentromeric regions. During early leptotene, proximal chromosome parts cluster and form a highly polarized Rabl configuration. Telomeres associated in pairs were seen at zygotene. The high degree of polarization of meiotic nuclei continues for an exceptionally long period, i.e., during zygotene–pachytene into the diplotene contraction stage. The Rabl-polarized meiotic architecture and clustering of pericentromeres suggest a high complexity of karyotypes, not only in structural heterozygotes but also in bivalent-forming homozygous species.

scholarly journals Polarimetric and Photometric Investigations of Lacertids

1987 ◽  
Vol 121 ◽  
pp. 325-327
Author(s):  
V.A. Hagen-Thorn ◽  
V.A. Yacovleva
Keyword(s):  
Astronomical Observatory ◽  
Degree Of Polarization ◽  
State University ◽  
Bl Lac ◽  
High Degree ◽  
Direction Of Polarization ◽  
Photographic Photometry

At the Astronomical Observatory of Leningrad State University two observational programs of investigation of lacertids - photographic photometry and photoelectric polarimetry - are in progress for many years. Some results for OJ 287 and BL Lac are of interest: (1) existence of preferable direction of polarization, (2) correlations between the brightness and polarization parameters, and (3) high degree of polarization (~50%) of individual sources responsible for variability.

scholarly journals NonRadial Pulsations and the Be Phenomenon

1987 ◽  
Vol 92 ◽  
pp. 463-463
Author(s):  
G. D. Penrod
Keyword(s):  
Relaxation Oscillation ◽  
Radial Pulsation ◽  
Be Stars ◽  
B Stars ◽  
Long Period ◽  
Period 2 ◽  
Short Period ◽  
Essential Components ◽  
Emission Stars ◽  
High Degree

AbstractOver the last three years I have obtained about 2000 spectra of a sample of 25 rapidly rotating Bn and Be stars. All but two of the program stars show obvious line-profile variations due to non-radial oscillations. The non-emission stars are each pulsating in one or two short-period high-degree (l = 4 to 10) modes, while the Be stars are in all cases pulsating in a long-period % = 2 mode, and often in a short-period high-Z mode as well. The amplitude of the pulsations in several stars (λ Eri, o And, ζ 0ph, and 2 Vul) is correlated with the occurrence of Be outbursts. The amplitude of the pulsations is largest before the outbursts, declines slowly during the emission phases to a fraction of its previous amplitude, and then slowly recovers to its previous amplitude, a few months before the onset of the next outburst. The correspondence between the presence of a long-period % = 2 mode and Ha emission in rapidly rotating B stars strongly suggests that non-radial pulsation and rapid rotation are the essential components which enable single early B stars to become Be stars. The time scale between Be outbursts probably reflects the relaxation oscillation cycle of the I = 2 mode excitation and damping.

scholarly journals Chromosome linkage in oenothera, with special reference to some F 1 hybrids

1929 ◽  
Vol 105 (736) ◽  
pp. 207-230 ◽  
Keyword(s):  
Embryo Sac ◽  
Reduction Division ◽  
Exact Nature ◽  
Chromosome Behaviour ◽  
Final Solution ◽  
Female Side ◽  
Chromosome Configuration ◽  
Pure Lines ◽  
Mother Cells ◽  
Derivatives Of

Oenothera has placed a large part in our initiation into many new fields of cytological and genetical research. Since ring-formation of chromosomes was first observed in this genus by Cleland a few years ago, it has become apparent as a characteristic of meiosis in several other Angiosperms, but whether these are entirely comparable to Oenothera is at present doubtful. It is to Oenothera that we look for the final solution of many of the difficulties encountered in any endeavour to correlate these phenomena with chromosome behaviour in more typical genera, for within the Onagra group are numerous inter-fertile species, each of which is characterised by its own particular chromosome configuration, which is constant throughout all the pollen mother-cells. Such rings are now known to occur also at reduction division in the embryo-sac mother-cell of a number of forms, and it has been found that similar configurations prevail on the male and female side in any particular species. This is observed by the author to be the ease in Oe. rubricalyx (unpublished) and similar conditions have been described by Håbansson (1928) in several other derivatives of Oe. Lamarckiana . It seemed that a systematic study of the linkage of the chromosomes in a number of pure lines and in the hybrids between them was desirable, in that it might throw some light on the exact nature of pairing and chromosome linkage. Some such hybrids have already been described by Cleland (1927). This paper will deal with the chromosome behaviour in a number of F 1 hybrids between pure lines in which the meiotic divisions have already been studied (Sheffield, 1927).

Cytogenetic analysis of translocation heterozygosity in the common bean (Phaseolus vulgaris L.)

1986 ◽  
Vol 28 (4) ◽  
pp. 574-580 ◽  
Author(s):  
M. Ashraf ◽  
M. J. Bassett
Keyword(s):  
Phaseolus Vulgaris ◽  
Common Bean ◽  
Chromosome Translocation ◽  
Phaseolus Vulgaris L ◽  
Reciprocal Translocations ◽  
Chromosome Translocations ◽  
Ovule Abortion ◽  
Translocation Heterozygosity ◽  
The Common ◽  
Half Diallel

Twelve semisterile lines of Phaseolus vulgaris L. (2n = 22) were reported previously by this laboratory. Here we verify through cytological investigations that 5 of the 12 stocks are indeed chromosome translocations. Cytological analysis of a half diallel set of crosses indicates that these five stocks involve eight different chromosomes in reciprocal translocations. Pollen and ovule abortion rates increase with the increasing number of interchanges in a stock. Cytological behavior and morphological abnormalities with respect to pollen and ovule abortion produced by translocation heterozygosity in the common bean, as observed in this study, are similar to those reported in other crops.Key words: Phaseolus, chromosome translocation, translocation heterozygosity.

scholarly journals Art, auto-mechanics, and supramolecular chemistry. A merging of hobbies and career

2016 ◽  
Vol 12 ◽  
pp. 362-376 ◽  
Author(s):  
Eric V Anslyn
Keyword(s):  
Supramolecular Chemistry ◽  
Self Assembly ◽  
Molecular Orbital Theory ◽  
High Complexity ◽  
Orbital Theory ◽  
Non Covalent Interactions ◽  
Definition Of ◽  
High Degree ◽  
Covalent Interactions ◽  
Strict Definition

While the strict definition of supramolecular chemistry is “chemistry beyond the molecule”, meaning having a focus on non-covalent interactions, the field is primarily associated with the creation of synthetic receptors and self-assembly. For synthetic ease, the receptors and assemblies routinely possess a high degree of symmetry, which lends them an aspect of aesthetic beauty. Pictures of electron orbitals similarly can be seen as akin to works of art. This similarity was an early draw for me to the fields of supramolecular chemistry and molecular orbital theory, because I grew up in a household filled with art. In addition to art, my childhood was filled with repairing and constructing mechanical entities, such as internal combustion motors, where many components work together to achieve a function. Analogously, the field of supramolecular chemistry creates systems of high complexity that achieve functions or perform tasks. Therefore, in retrospect a career in supramolecular chemistry appears to be simply an extension of childhood hobbies involving art and auto-mechanics.

A LIGHT-MICROSCOPIC STUDY OF SOME TRANSLOCATIONS IN ASPERGILLUS NIDULANS

1978 ◽  
Vol 20 (3) ◽  
pp. 325-328 ◽  
Author(s):  
E. R. Boothroyd
Keyword(s):  
Aspergillus Nidulans ◽  
Meiotic Chromosome ◽  
Low Frequency ◽  
Chromosome Analysis ◽  
Chromosome Behaviour ◽  
Structural Detail ◽  
Linkage Groups ◽  
Limited Evidence ◽  
Control Material ◽  
Reciprocal Translocations

A cytological investigation of the ascomycete, Aspergillus nidulans (Eidam) Winter, was undertaken to test the feasibility of using simple light-microscopial techniques to study chromosome aberrations for the correlation of chromosomes and linkage groups in this genetically well analysed fungus. Pachytene chromosome analysis was not possible, because the chromosomes are very small, do not spread well when squashed, and show very little structural detail. Some catenations were seen at first metaphase in translocation heterozygotes either as dense masses or, more rarely, as open rings. Lagging chromosomes were also seen at low frequency in both first and second anaphase and telophase in translocation but not in control material. The limited evidence from the study shows that meiotic chromosome behaviour in Aspergillus nidulans heterozygous for reciprocal translocations is probably similar to that in some higher organisms. However, the species is not suitable for detailed cytological analysis, at least by the techniques employed.

scholarly journals Cellular and molecular mechanisms underlying axon formation, growth, and branching

2013 ◽  
Vol 202 (6) ◽  
pp. 837-848 ◽  
Author(s):  
Tommy L. Lewis ◽  
Julien Courchet ◽  
Franck Polleux
Keyword(s):  
Cell Biology ◽  
Molecular Mechanisms ◽  
Axon Growth ◽  
Adult Brain ◽  
Degree Of Polarization ◽  
Axonal Development ◽  
Terminal Axon ◽  
Axon Specification ◽  
High Degree ◽  
Neuronal Polarization

Proper brain wiring during development is pivotal for adult brain function. Neurons display a high degree of polarization both morphologically and functionally, and this polarization requires the segregation of mRNA, proteins, and lipids into the axonal or somatodendritic domains. Recent discoveries have provided insight into many aspects of the cell biology of axonal development including axon specification during neuronal polarization, axon growth, and terminal axon branching during synaptogenesis.

scholarly journals Generating a Strong Key for a Stream Cipher Systems Based on Permutation Networks

2007 ◽  
Vol 4 (3) ◽  
pp. 501-504
Author(s):  
Baghdad Science Journal
Keyword(s):  
Communication Systems ◽  
Stream Cipher ◽  
Linear Feedback ◽  
High Complexity ◽  
Long Period ◽  
Auto Correlation ◽  
Crossbar Switches ◽  
Feedback Shift Register ◽  
Pn Sequences ◽  
Randomness Tests

The choice of binary Pseudonoise (PN) sequences with specific properties, having long period high complexity, randomness, minimum cross and auto- correlation which are essential for some communication systems. In this research a nonlinear PN generator is introduced . It consists of a combination of basic components like Linear Feedback Shift Register (LFSR), ?-element which is a type of RxR crossbar switches. The period and complexity of a sequence which are generated by the proposed generator are computed and the randomness properties of these sequences are measured by well-known randomness tests.

scholarly journals National scenario of procedures for intracranial tumor exerisis

2021 ◽  
Author(s):  
Paulo Roberto Hernandes Júnior ◽  
Juliana de Souza Rosa ◽  
Patrick de Abreu Cunha Lopes ◽  
Bárbara Tisse da Silva ◽  
Heloá Santos Faria da Silva ◽  
...  
Keyword(s):  
Public Sector ◽  
Mortality Rate ◽  
Hospital Stay ◽  
Intracranial Tumors ◽  
High Complexity ◽  
Cross Sectional ◽  
Private Care ◽  
The Public ◽  
Long Period ◽  
Treatment Procedures

Background: Intracranial tumors have an incidence that varies between 10 to 17 cases per 100 thousand people. Objectives: To analyze the panorama of craniotomy treatment procedures for removal of intracranial tumors in the State of São Paulo and correlate it with the current epidemiology. Methods: observational, descriptive and cross-sectional collection of craniotomy treatment for removal of intracranial tumors, available at DATASUS website, from January 2008 up to December 2020 - evaluating the number of hospitalizations, public spending, complexity, mortality rate, deaths, permanence and character of care. Results: 9,569 hospitalizations were observed for such procedures in this period, representing a total expenditure of R$ 39,104,400.74. 2013 was the year with the highest number of hospitalizations (880), it was also the year with the greatest expenditure (R$ 3,729,954.75). 3,204 of them were elective and 6,365 were urgent, with 4,550 occurring in the public sector and 1,519 in private one. All 9,569 considered to be of high complexity. The mortality rate was 9.31, corresponding to 891 deaths, 2008 was the year with the highest mortality, 11.64 and 2018 the lowest, 6.29. Mortality rate was lower in elective procedures (6.27 versus 10.84 in urgent ones) and when carried out in public sector (9.27 versus 9.61 in private care). The hospital stay was 17.0 days, with a cost of R$ 4,086.57. Conclusion: The excision of intracranial tumors represents a procedure of high complexity with a long period of hospital stay. Higher mortality was observed in emergency care and the private sector.

scholarly journals High degree of polarization of the near-band-edge photoluminescence in ZnO nanowires

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Gwenole Jacopin ◽  
Lorenzo Rigutti ◽  
Andres De Luna Bugallo ◽  
François Henry Julien ◽  
Camilla Baratto ◽  
...  
Keyword(s):  
Zno Nanowires ◽  
Band Edge ◽  
Degree Of Polarization ◽  
Near Band Edge ◽  
High Degree
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