Cytogenetics of an unstable trisomie in barley (Hordeum vulgare)

The origin, identification, meiotic chromosome behavior, and breeding behavior of an unstable trisomic barley were studied. The extra chromosome originated by breakage and fusion of an acrocentric chromosome 3 in a plant from an F2 population of a cross between acrotrisomic 3L3S (2n = 14 + 1 acro3L3S) and a balanced lethal stock, xc. (xantha) ac (albino). The F2 population segregated only for the albino trait. The genotypic constitution of the trisomic plant was ac ac (for both normal chromosome 3) and Ac (for the unstable metacentric chromosome). The unstable extra metacentric chromosome was designated as metacentric 3B (abbreviated as meta3B). Meiotic chromosome behavior in plants with 2n = 14 + 1 meta3B differed from plant to plant and within spikes. Some plants showed only trisomic cells with a chromosome configuration of 1 III + 6 II and 7 II + 1 I at metaphase I, whereas other plants showed both trisomie and disomic cells (7 II) that resulted from the elimination of the extra meta3B. The frequency of ring trivalents was low (6.8%). An average transmission rate of unstable meta3B ranged from 4.3 to 12.9%. The elimination of meta3B, and hence loss of the dominant Ac allele, resulted in albino seedlings as well as white stripes on plants, leaves, and spikes. Chromosome numbers of albino seedlings in the progeny of 2n = 14 + 1 meta3B were all diploid (2n = 14), while green seedlings contained 2n = 14 + 1 meta3B. However, progenies of some spikes of one trisomic plant showed a low frequency of green diploids and metatrisomics (2n = 14 + 1 meta3B), which was attributed to crossing-over.Key words: aneuploid, chromosome elimination, kinetochore, meta3B.

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TRISOMIC TRANSMISSION IN LOTUS PEDUNCULATUS

Canadian Journal of Genetics and Cytology ◽

10.1139/g68-082 ◽

1968 ◽

Vol 10 (3) ◽

pp. 648-654 ◽

Cited By ~ 17

Author(s):

Chi-Chang Chen ◽

W. F. Grant

Keyword(s):

Pollen Germination ◽

Transmission Rate ◽

Extra Chromosome ◽

Low Frequency ◽

Pollen Grains ◽

Tube Growth ◽

Male Gametes ◽

Meiotic Irregularities ◽

Significant Difference ◽

Lotus Pedunculatus

Transmission of the extra chromosome was studied for four primary trisomic types of Lotus pedunculatus Cav., named Broad, Pointed, Narrow, and Small (trisomic for chromosomes 3, 4, 5 and 6, respectively). Despite the low frequency of transmission (average 9.2%), parental trisomics were recovered in all of the four trisomic types. No significant difference was found between pollen and ovule transmission. It was suggested that either there is no difference in germination and tube growth between the n and n + 1 pollen grains, or selection against the n + 1 male gametes in pollen germination and tube growth is balanced by the mechanism (s) selecting against the n + 1 female gametes. Although there were variations in transmission rate within the same trisomic types, the shorter extra chromosomes tended to be transmitted more frequently than the longer ones. This was interpreted as reflecting the degree of genic unbalance created by the extra chromosome in gametes and zygotes. The longer the extra chromosome, the greater would be the unbalance, and hence the less chance there would be for the n + 1 gametes and 2n + 1 zygotes to be viable. The trisomic types Small and Narrow produced a few unrelated trisomics in their progenies. It was considered that meiotic irregularities in these trisomic types could account for the production of such unrelated trisomics.

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An Effective Congestion Control Algorithm based on Traffic Assignment and Reassignment in Wireless Sensor Network

Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) ◽

10.2174/2352096513999200628095848 ◽

2020 ◽

Vol 13 (8) ◽

pp. 1166-1174

Author(s):

Chao Wang

Keyword(s):

Wireless Sensor Network ◽

Congestion Control ◽

Sensor Network ◽

Traffic Assignment ◽

Transmission Rate ◽

Sensor Nodes ◽

Wireless Sensor ◽

Congestion Detection ◽

Detection Technology ◽

Average Transmission

Background: It is important to improve the quality of service by using congestion detection technology to find the potential congestion as early as possible in wireless sensor network. Methods: So an improved congestion control scheme based on traffic assignment and reassignment algorithm is proposed for congestion avoidance, detection and mitigation. The congestion area of the network is detected by predicting and setting threshold. When the congestion occurs, sensor nodes can be recovery quickly from congestion by adopting reasonable method of traffic reassignment. And the method can ensure the data in the congestion areas can be transferred to noncongestion areas as soon as possible. Results: The simulation results indicate that the proposed scheme can reduce the number of loss packets, improve the throughput, stabilize the average transmission rate of source node and reduce the end-to-end delay. Conclusion: : So the proposed scheme can enhance the overall performance of the network. Keywords: wireless sensor network; congestion control; congestion detection; congestion mitigation; traffic assignment; traffic reassignment.

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Meiotic chromosome behavior of Haworthia limifolia

International Journal of Bioassays ◽

10.21746/ijbio.2016.03.009 ◽

2016 ◽

Vol 5 (03) ◽

pp. 4902

Author(s):

Afrin Nazli ◽

Kamini Kumar*

Keyword(s):

Genetic Recombination ◽

Meiotic Chromosome ◽

Pollen Sterility ◽

Meiotic Abnormalities ◽

Chromosome Behavior ◽

The Family ◽

Medicinal Properties ◽

Fruit Formation ◽

Meiosis I ◽

Chromosomal Behaviour

Haworthia limifolia is a xerophytic plant belonging to the family Liliaceae and is indigenous to Africa. It is use extensively for its medicinal properties like antibacterial, antifungal properties and used for the treatment of sores, superficial burns, as a blood purifier and to promote pregnancy in women and cattles. In present investigation chromosomal behaviour of H. limifolia in meiosis was studied. In diplotene stage chiasmata was observed showing the possibilities of genetic recombination. Chromosome clumps were observed in diakinesis indicating sticky nature of chromosomes. Meiotic abnormalities like stickiness, precocious movement, formation of bridges and laggards were also reported in both meiosis I and II. A fairly high percentage of pollen sterility that is 73.41% was recorded resulting in failure of fruit formation. This plant could be designated as facultative apomict (Swanson, 1957) as the only means of reproduction found was asexual or vegetative.

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Intergeneric hybrids of Hordeum vulgare with Agropyron caninum and A. dasystachyum

Canadian Journal of Genetics and Cytology ◽

10.1139/g85-057 ◽

1985 ◽

Vol 27 (4) ◽

pp. 387-392 ◽

Cited By ~ 6

Author(s):

George Fedak

Keyword(s):

Hordeum Vulgare ◽

Chromosome Pairing ◽

Meiotic Chromosome ◽

Intergeneric Hybrids ◽

Spindle Fibre ◽

Chromosome Behavior ◽

Paternal Parent ◽

Agropyron Caninum

Hybrids were obtained by pollinating Hordeum vulgare cv. Betzes with Agropyron caninum (4x) and A. dasystachyum (4x) at frequencies of 1.4 and 6.1% of pollinated florets, respectively. The hybrids were sterile and phenotypically resembled the paternal parent, except for floret structure which was intermediate between the parental types. Chromosome pairing at meiosis was very low and thus provided no indication of homoeology between parental genomes. Abnormal meiotic chromosome behavior in meiocytes that occurred in sectors on the 'Betzes' × A. dasystachyum hybrid was attributed to abnormal spindle fibre function.Key words: intergeneric hybrids, Hordeum vulgare, Agropyron caninum, Agropyron dasystachyum.

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Meiotic Chromosome Behavior in Rhoeo spathacea

Journal of Heredity ◽

10.1093/oxfordjournals.jhered.a108443 ◽

1973 ◽

Vol 64 (6) ◽

pp. 365-368 ◽

Cited By ~ 5

Author(s):

THOMAS R. MERTENS

Keyword(s):

Meiotic Chromosome ◽

Chromosome Behavior

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Chromosome 3 Duplication q/Deletion p Syndrome

PEDIATRICS ◽

10.1542/peds.61.4.611 ◽

1978 ◽

Vol 61 (4) ◽

pp. 611-618

Author(s):

Robert M. Fineman ◽

Frederick Hecht ◽

Ronald C. Ablow ◽

Rufus O. Howard ◽

W. Roy Breg

Keyword(s):

Spina Bifida ◽

Extra Chromosome ◽

Psychomotor Retardation ◽

Chromosome 3 ◽

Cardiovascular Disorders ◽

Radiological Findings ◽

Recombinant Chromosome ◽

X Ray ◽

Digital Impressions ◽

Ocular Hypertelorism

This report describes the clinical, chromosomal, and radiological findings in four unrelated families with different recombinant chromosome 3 abnormalities. On the basis of the phenotypic and cytogenetic findings seen in our six patients and those noted in two recent reports, we concur with Allderdice et al. that the syndrome in which the long arm (q) of chromosome 3 is duplicated and the short arm (p) is deleted is a distinct clinical entity. The psychomotor retardation found in this syndrome appears to be caused mostly by monosomy of the region 3pter→3p25, while severity of the physical malformations (and hence the lethality) is apparently proportional to the amount of extra chromosome 3q material present. That is, patients who are trisomic for larger segments are physically more affected than patients who are trisomic for smaller amounts of the long arm of chromosome 3. Features common to the chromosome 3 duplication q/deletion p syndrome are mental and growth retardation, microcephaly, seizures, prominent and/or asymmetric frontal bossing, ocular hypertelorism, ptosis, upward-slanting palpebral fissures, and low-set and/or malformed ears. Other anomalies frequently seen are short webbed neck, various types of congenital cardiovascular disorders, omphalocele, cryptorchidism, spina bifida, short digits, hypotonia, and digital impressions on skull x-ray examination which are presumably caused by trisomy for the distal band (3q28) of the long arm of chromosome 3. In addition, the importance of doing chromosome studies in persons who are mildly affected, both mentally and physically, is illustrated by the study of one of these families.

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Role of microtubules and microtubule organizing centers on meiotic chromosome elimination in Sciara ocellaris

Journal of Cell Science ◽

10.1242/jcs.110.6.721 ◽

1997 ◽

Vol 110 (6) ◽

pp. 721-730 ◽

Cited By ~ 3

Author(s):

M.R. Esteban ◽

M.C. Campos ◽

A.L. Perondini ◽

C. Goday

Keyword(s):

Meiotic Chromosome ◽

Chromosome Elimination ◽

Male Meiosis ◽

Meiotic Spindle ◽

Monopolar Spindle ◽

Meiotic Spindles ◽

Cytoplasmic Microtubules ◽

Spindle Microtubules ◽

Meiosis I

Spindle formation and chromosome elimination during male meiosis in Sciara ocellaris (Diptera, Sciaridae) has been studied by immunofluorescence techniques. During meiosis I a monopolar spindle is formed from a single polar complex (centrosome-like structure). This single centrosomal structure persists during meiosis II and is responsible for the non-disjunction of the maternal X chromatids. During meiosis I and II non-spindle microtubules are assembled in the cytoplasmic bud regions of the spermatocytes. The chromosomes undergoing elimination during both meiotic divisions are segregated to the bud region where they associate with bundles of microtubules. The presence and distribution of centrosomal antigens in S. ocellaris meiotic spindles and bud regions has been investigated using different antibodies. gamma-Tubulin and centrin are present in the bud as well as in the single polar complex of first meiotic spindle. The results suggest that spermatocyte bud regions contain microtubule-organizing centres (MTOCs) that nucleate cytoplasmic microtubules that are involved in capturing chromosomes in the bud regions. The distribution of actin and myosin in the spermatocytes during meiosis is also reported.

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