The karyotype of Alouattapigra (Primates: Platyrrhini): mitotic and meiotic analyses

2008 ◽  
Vol 122 (2) ◽  
pp. 103-109 ◽  
Author(s):  
E.R. Steinberg ◽  
L. Cortés-Ortiz ◽  
M. Nieves ◽  
A.D. Bolzán ◽  
F. García-Orduña ◽  
...  
Keyword(s):  
Meiotic Analyses

Identification and characterization of the centromere from chromosome XIV in Saccharomyces cerevisiae

1985 ◽  
Vol 5 (11) ◽  
pp. 2887-2893
Author(s):  
M Neitz ◽  
J Carbon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Restriction Fragment ◽  
Dna Sequences ◽  
Yeast Genome ◽  
Ura3 Gene ◽  
Dna Restriction ◽  
Meiotic Analyses ◽  
The Right ◽  
In Cis

A functional centromere located on a small DNA restriction fragment from Saccharomyces cerevisiae was identified as CEN14 by integrating centromere-adjacent DNA plus the URA3 gene by homologous recombination into the yeast genome and then by localizing the URA3 gene to chromosome XIV by standard tetrad analysis. DNA sequence analysis revealed that CEN14 possesses sequences (elements I, II, and III) that are characteristic of other yeast centromeres. Mitotic and meiotic analyses indicated that the CEN14 function resides on a 259-base-pair (bp) RsaI-EcoRV restriction fragment, containing sequences that extend only 27 bp to the right of the element I to III region. In conjunction with previous findings on CEN3 and CEN11, these results indicate that the specific DNA sequences required in cis for yeast centromere function are contained within a region about 150 bp in length.

scholarly journals Monocentric chromosomes in Juncus (Juncaceae) and implications for the chromosome evolution of the family

2019 ◽  
Vol 191 (4) ◽  
pp. 475-483 ◽  
Author(s):  
Marcelo Guerra ◽  
Tiago Ribeiro ◽  
Leonardo P Felix
Keyword(s):  
In Situ Hybridization ◽  
Fluorescent In Situ Hybridization ◽  
Chromosome Evolution ◽  
Holocentric Chromosomes ◽  
Mitotic Chromosomes ◽  
Restricted Area ◽  
Rdna Sites ◽  
The Family ◽  
Meiotic Analyses

Abstract Holocentric chromosomes are rare among angiosperms, but have been suggested to be shared by all or most of the species of Cyperaceae and Juncaceae. However, no clear demonstration of the centromere type in Juncus, the largest genus of Juncaceae, has so far been published. Thus, we conducted a detailed chromosomal investigation of four Juncus spp. aiming to identify their centromere type. Mitotic chromosomes were analysed using the fluorochromes CMA and DAPI, fluorescent in situ hybridization (FISH) with rDNA probes and immunodetection of histones H3 phosphorylated at serine 10 (H3-S10ph) and H2A phosphorylated at threonine 133 (H2A-T133ph). DAPI-stained chromosomes of all species displayed typical primary constrictions, which were not related to AT-poor CMA+ heterochromatin or rDNA sites (usually negatively stained with DAPI). Immunodetection with H3-S10ph and H2A-T133ph revealed hyperphosphorylation of pericentromeric and centromeric regions, respectively, in a restricted area, as observed in monocentric chromosomes. Meiotic analyses in J. microcephalus showed no indication of inverted meiosis, commonly found in plants with holocentric chromosomes. Since the species investigated here belong to four different sections of Juncus and all of them display typical monocentric chromosomes, it seems that this kind of centromere is common in the genus and may represent the standard centromere organization for Juncus. If Juncus has monocentric chromosomes, there is no reason to hypothesize that other genera of Juncaceae for which centromeres have not been carefully investigated have holocentric chromosomes.

Transmission of an alien telocentric addition chromosome in common wheat that confers blue seed color

Genome ◽  
1989 ◽  
Vol 32 (1) ◽  
pp. 30-34 ◽  
Author(s):  
E. D. P. Whelan
Keyword(s):  
Triticum Aestivum ◽  
Common Wheat ◽  
Triticum Aestivum L ◽  
Seed Color ◽  
Chromosome Behavior ◽  
Phenotypic Markers ◽  
Telocentric Chromosome ◽  
Cytogenetic Studies ◽  
Meiotic Analyses ◽  
Color Gene

Phenotypic markers of chromosomes are useful for determining chromosome behavior in cytogenetic studies. Transmission of an alien, telocentric addition from Agropyron tricophorum (Link) Richt. that confers purple aleurone pigment and blue seed color was evaluated in common wheat (Triticum aestivum L.). Twenty-five of 2570 seeds from bagged heads of eight ditelocentric-addition sister plants were almost white rather than blue. Seven of these 25 seeds and 4 of 336 blue seeds segregated 41.4%:58.6% blue:white. Meiotic analyses showed that all plants grown from these 11 seeds were spontaneously produced monotelocentric additions. Transmission of the alien telocentric chromosome through the egg and the pollen was estimated to be 19.5 and 14.3%, respectively, based on BC1F1 seed color. About 28% of F2 and F3 seeds were blue; of these 7.4% were ditelocentric additions. The frequency of blue seed in F2 progeny from spontaneous monotelocentric additions (41.4%) was significantly greater than that of monotelocentric additions from controlled crosses (28%). Penetrance of the blue seed color gene(s) associated with the alien telocentric chromosome was good. Misclassification of seed color for 1595 BC1F1 seeds was less than 3% based on BC1F2 progeny.Key words: Agropyron tricophorum.

Meiotic abnormalities in primary regenerants from callus culture of immature embryos of 'Norstar' winter wheat

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 260-266 ◽  
Author(s):  
Ernest D. P. Whelan
Keyword(s):  
Triticum Aestivum ◽  
Tissue Culture ◽  
Winter Wheat ◽  
Structural Changes ◽  
Chromosome Structure ◽  
Triticum Aestivum L ◽  
Immature Embryos ◽  
Meiotic Abnormalities ◽  
Chromosomal Changes ◽  
Meiotic Analyses

Tissue culture can induce changes in chromosome structure and number in common wheat (Triticum aestivum L.). The type and frequency of such changes were evaluated in primary regenerants extracted from calli of four immature embryos of 'Norstar' winter wheat cultured for various durations. Meiotic analyses of samples from 18 or 19 primary regenerants from a single embryo cultured for 6, 10, or 14 weeks detected chromosomal changes in 17–20% of the samples. Analyses of 20 duplicate samples from these plants indicated that 7 (35%) plants were chimeras. Similar analyses for nine duplicate samples from plants extracted from an embryo cultured for 18 weeks failed to detect any chimeras, but meiotic abnormalities were much more frequent, with about one-half of the 46 plants sampled showing chromosomal structural changes; translocations were the most common abnormality. Plants regenerated from this embryo also were characterized by an abnormal chromosome, believed to contain a deletion, that was not considered to have been induced by tissue culture.Key words: tissue culture, meiotic abnormalities, Triticum aestivum, aneuploidy, translocations, chimeras.

Chromosome 5D instability in cell lines of Triticum tauschii and morphological variation in regenerated plants

Genome ◽  
1995 ◽  
Vol 38 (4) ◽  
pp. 737-742 ◽  
Author(s):  
M. O. Winfield ◽  
A. Karp ◽  
P. A. Lazzeri ◽  
M. R. Davey
Keyword(s):  
Seed Set ◽  
Immature Embryo ◽  
Cell Suspensions ◽  
Chromosome Counts ◽  
Triticum Tauschii ◽  
Regenerated Plants ◽  
Immature Embryo Culture ◽  
Meiotic Analyses ◽  
L2 Medium ◽  
Indole 3 Acetic Acid

Immature embryos of Triticum tauschii cultured on L2 medium with 30 g∙L−1maltose gave rise to compact and highly structured callus that readily regenerated shoots when transferred to MS medium supplemented with zeatin and indole-3-acetic acid. Two cell suspensions were initiated from the callus induced on L2 medium. An analysis of chromosome number in these cell suspensions after 3 months of culture showed that 95 and 75% of the cells had a normal complement. After 5 months, in both lines the majority of cells had chromosome complements of 2n = 13 and many of these aneuploid cells possessed a dicentric chromosome. C-banding indicated that the dicentric was often formed from chromosomes 2D and 5D. Fifty-six plants regenerated from callus were grown to maturity. Variation was observed in tiller number, flowering time, and seed-set; in two cases, the variation in early flowering was shown to be heritable. All the regenerants analysed had normal chromosome counts (2n = 2x = 14) and meiotic analyses of 35 plants revealed no obvious structural rearrangements.Key words: immature embryo culture, regeneration, chromosome, cell suspension, Triticum tauschii.

Synthetic and natural hybrids of Psathyrostachys huashanica

Genome ◽  
1987 ◽  
Vol 29 (6) ◽  
pp. 811-816 ◽  
Author(s):  
Richard R. -C. Wang
Keyword(s):  
Intergeneric Hybrid ◽  
Meiotic Pairing ◽  
Psathyrostachys Huashanica ◽  
Spike Morphology ◽  
Natural Hybrids ◽  
Close Relationship ◽  
Synthetic Hybrids ◽  
Meiotic Analyses ◽  
Mother Cells ◽  
The Relationship

Three synthetic hybrids and two natural hybrids involving Psathyrostachys huashanica are reported. Gross spike morphology of the hybrids of Pseudoroegneria cognata and Pseudoroegneria spicata ssp. inermis with P. hauashanica was not as indicative of hybridity as in other hybrids involving P. huashanica. Meiotic analyses of these two synthetic hybrids confirmed that little homology exists between the genomes S and Nh. Coenocytism in the hybrids P. huashanica × Secale montanum led to the formation of pseudomicrospores in nondehiscent anthers. No metaphase through telophase chromosome stages could be observed and thus the relationship between genomes Nh and R could not be assessed. Intermediate spike morphology of, and the sterility in, natural hybrids of P. huashanica with P. fragilis and P. juncea substantiated their hybridity. High meiotic pairing in hybrids between P. huashanica and P. fragilis, averaging 1.03 I + 6.48 II, indicated a close relationship between the two species. Occasional high pairing and frequent abnormal meiosis, manifested by degenerating prophase pollen mother cells (PMCs) and empty anthers lacking PMCs of later stages, in the hybrid P. huashanica × P. juncea suggested a more distant relationship between the parental species. It is concluded that P. fragilis is more closely related to P. huashanica than P. juncea. Key words: hybrid (intergeneric), hybrid (interspecific), genome, coenocyte, chromosome diminution, Psathyrostachys, Pseudoroegneria, Secale.

scholarly journals Chromosome Number and Meiotic Behavior of Cultivated Chia, Salvia hispanica (Lamiaceae)

HortScience ◽  
1990 ◽  
Vol 25 (12) ◽  
pp. 1646-1647 ◽  
Author(s):  
A. Estilai ◽  
A. Hashemi ◽  
K. Truman
Keyword(s):  
Chromosome Number ◽  
Species Identification ◽  
Southern California ◽  
Herbarium Specimens ◽  
Meiotic Behavior ◽  
Root Tips ◽  
Chromosome Counts ◽  
Salvia Hispanica ◽  
Meiotic Analyses ◽  
Metaphase I

Edible chia seeds, purchased from the local markets in Guatemala, Mexico, and southern California, were used for species identification, chromosome counts, karyotype construction, and meiotic analyses. Plants raised from those seeds had ovate leaves, dense racemose inflorescences, pale-blue flowers, and were identified from herbarium specimens as Salvia hispanica L. Mitotic analyses of root tips from 50 plants showed 2n = 12—the lowest chromosome number in the genus. Chromosomes were small, ranging from 2 to 3.5 pm. One pair of chromosomes was metacentric (with the long arm: short arm ratio, r = 1.5), four pairs were submetacentric (r = 2.6 to 3.6), and one pair was telocentric (r = 12). Meiosis was regular and six bivalents were observed at metaphase I. Ring and rod bivalents averaged 1.53 ± 1.05 and 4.47 ± 1.05, respectively;

THE ANALYSIS OF MEIOSIS IN HYBRIDS. II. TRIPLOID HYBRIDS

1981 ◽  
Vol 23 (2) ◽  
pp. 221-234 ◽  
Author(s):  
L. C. Alonso ◽  
G. Kimber
Keyword(s):  
Quantitative Determination ◽  
Relative Affinity ◽  
Genomic Relationships ◽  
Meiotic Analyses

Methods are developed that allow a quantitative determination of relative affinity in triploid hybrids. This results in new insights into the analysis of meiosis in hybrids, genomic relationships and the assignment of genome symbols. The separate recording of open and closed chromosome figures in meiotic analyses is shown to be essential.

Genome analysis of Thinopyrum caespitosum

Genome ◽  
1989 ◽  
Vol 32 (1) ◽  
pp. 141-145 ◽  
Author(s):  
Zhi-Wu Liu ◽  
Richard R. -C. Wang
Keyword(s):  
Genome Analysis ◽  
Karyotype Analysis ◽  
Tetraploid Species ◽  
Genomic Constitution ◽  
Meiotic Analyses

Karyotype and meiotic analyses of the triploid hybrids Pseudoroegneria libanotica (Hackel) A. Löve (2n = 2x = 14; SS) × Thinopyrum caespitosum (C. Koch) R. R.-C. Wang (2n = 4x = 28) and T. bessarabicum (Saval &Rayss) A. Löve (2n = 2x = 14; JJ) × T. caespitosum (2n = 4x = 28) were performed to study the genomic constitution of T. caespitosum. Karyotype analysis of T. caespitosum was also carried out. In all karyotypic studies, the observed ratios between the longest and shortest chromosomes in the genome complements of the tetraploid species and triploid hybrids were higher than the hypothetical one based on the assumption that T. caespitosum has both Je and S genomes. This indicates that amphiplasty occurs at both the triploid and tetraploid levels. The hypothesis that T. caespitosum is an autotetraploid, either JJJJ (JJJeJe) or SSSS, is rejected. The meiotic data, 4.83 I + 0.78 rod II + 4.09 ring II + 2.14 III for P. libanotica × T. caespitosum and 5.16 I + 2.71 rod II + 2.16 ring II + 1.99 III for T. bessarabicum × T. caespitosum, support the hypotheses that the former has SSJe and the latter has JJeS as the genome formula. This evidence and that from other relevant hybrids strongly suggest that T. caespitosum is a true allotetraploid with the genome formula JeJeSS.Key words: karyotype, meiosis, phylogeny, amphiplasty, genome, Lophopyrum, Thinopyrum, Agropyron, Pseudoroegneria.

scholarly journals Meiotic and mitotic behaviour of B chromosomes of ryegrass

2009 ◽  
Vol 40 (1) ◽  
pp. 83-88 ◽  
Author(s):  
Vânia Helena Techio ◽  
Andréa Mittelmann ◽  
Simone Marció ◽  
Antônio Vander Pereira
Keyword(s):  
Rio Grande ◽  
B Chromosomes ◽  
Rio Grande Do Sul ◽  
Anther Tapetum ◽  
Root Meristems ◽  
Fluorescent Stains ◽  
Meiotic Analyses ◽  
Metaphase I

Mitotic and meiotic analyses using conventional and fluorescent stains were employed in plants (accession ETBAZ 055 - origin: Capão do Leão, Rio Grande do Sul State, Brazil) from the Germplasm Active Bank of Ryegrass (Banco Ativo de Germoplasma de Azevém) of Embrapa, for observing the behaviour of B chromosomes. In several meiotic stages, there were observed up to two B chromosomes, which have presented an unstable behaviour regarding their precocious ascension to metaphase I or delays during anaphase I. At the end of the process, the Bs showed predominantly segregation for the nuclei under formation in order to guarantee their propagation. Concerning the cells that comprise the anther tapetum and the root meristems, the B chromosomes have presented a more stable behaviour.

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