The chromosomes

White, Michele

doi:10.5962/bhl.title.7458

Cited by 23 publications

(12 citation statements)

References 1 publication

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“…la should be mitotic metaphase as stated earlier. The chromosomes of Z variegatus are therefore acrocentric, a conclusion which is consistent with the appearances of the chromosomes in the mitotic and meiotic stages observed and the karyotype in the family Pyrogomorphidae (White 1973). …”

Section: Resultssupporting

confidence: 57%

Chromosome Morphology and Meiosis in Zonocerus Variegatus L. (Orthoptera, Pyrgomorphidae).

Williams¹,

Ogunbiyi²

1995

CYTOLOGIA

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The grasshopper, Zonocerus variegatus of the family Pyrogomorphidae has a male diploid chromosome number of 19, with an XO constitution (Oyidi 1968, Lasebikan andOlorode 1972). Although these investigators described the chromosomes as acrocentric, Nwankiti (1983b) described them as metacentric. The meiotic aberrations detected by Lasebikan and Olorode (1972) and Olorode and Akingbohungbe (1975) were not reported by Nwankiti, (1983a, b). Since the chromosomes of Z. variegatus are relatively large and not too many, it is not expected that there would be any disagreement on the morphology of the chromosomes. It should also be possible to detect consistent meiotic aberrations. This paper re-examines these issues. Materials and methodsThe fifty grasshoppers used for this study were adult males collected between January and May on the University of Lagos campus. They were killed with chloroform either on the day they were captured or on the next day. The grasshoppers were then dissected in 0.67% NaCI solution.Five fresh testicular follicles were placed on each glass slide, cut into three or four pieces and covered with a drop of 2% lactic-propionic orcein stain. After about 15 min, a cover glass was placed on the material. The cover glass was held in place while it was tapped gently with a dissecting needle, to disperse the cells and force out the excess stain. The preparation was squashed further between folds of bibulous paper to absorb the excess stain. The edges of the cover glass were sealed with nail varnish. Photomicrographs were made under the 100x oil immersion objective of a Wild M20 microscope with MPS 55 photoautomat attachment. Results and discussionChromosome Morphology:In spite of the fact that the grasshoppers were not treated with colchicine the individual chromosomes could be identified and counted in a polar view of the mitotic metaphase (Fig. la). The chromosomes appeared to be in C-metaphase because there was no relational coiling between sister chromatids. This appearance and the fact that what should be the short arms of the chromosomes were not clearly visible as paired structures (chromatids) could lead to misinterpretation, as by Nwankiti (1983b), that a pair of sister chromatids are instead the two arms of a folded metacentric chromosome. Close examination however, shows that there is a constriction separating the long arm from the short arm which also has some of the lampbrush appearance of the long arm. In addition, in some cases, the two chromatids of the short arm can be detected (Fig. la). The interpretation of folded metacentric chromosomes would be plausible only if the figure which Nwankiti (1983b) called mitotic telophase were so, but that is in fact a polar view of metaphase as in the present case. Furthermore, the mitotic anaphase/

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Section: Resultssupporting

confidence: 57%

Chromosome Morphology and Meiosis in Zonocerus Variegatus L. (Orthoptera, Pyrgomorphidae).

Williams¹,

Ogunbiyi²

1995

CYTOLOGIA

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“…The diploid DNA content (2C) of sea urchin P. lividus is 1.08 pg. The difference from the previously reported haploid GS of the same species (0.9 pg) (White 1961) could be attributed to different methodological approaches. The mean diploid DNA content (2C) of tunicate P. mammillata is 0.11 pg.…”

Section: Dna Contentcontrasting

confidence: 44%

Hemocytes/coelomocytes DNA content in five marine invertebrates: cell cycles and genome sizes

et al. 2008

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Abstract:The hemocytes/coelomocytes DNA content in five selected marine invertebrates (sea mouse Aphrodita aculeata, spiny crab Maja crispata, sea star Echinaster sepositus, sea urchin Paracentrotus lividus, and tunicate Phallusia mammillata) was investigated by flow cytometry. The cell cycle analyses identified sea mouse coelomocytes as proliferating cells and revealed that spiny crab hemocytes and sea urchin coelomocytes complete their division in the hemolymph and coelom, respectively. The genome sizes of sea mouse and spiny crab are reported for the first time. The diploid DNA content (2C) in sea mouse A. aculeate was 1.24 pg, spiny crab M. crispata 7.76 pg, red starfish E. sepositus 1.52 pg and sea urchin P. lividus 1.08 pg. The mean diploid DNA content in tunicate P. mammillata was 0.11 pg with a high interindividual variability (45%). The presented results provide a useful database for future studies in the field of invertebrate physiology, ecotoxicology, biodiversity, species conservation and phylogeny.

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“…Eucariotes [8] cells usually have linear chromosomes and cells procariotes [9]; [10]; [11] it has small groups of circular chromosomes.In eukaryotes, nuclear chromosomes are packaged by proteins into a condensed structure called chromatin. This allows the complete DNA molecule is found inside the nucleus.…”

Section: Chromosome Alterationsmentioning

confidence: 99%

The Importance of Clinical Genotype in Patients with Klinefelter Syndrome. A Genetic Disorder Asociated to Taurodontism

Castilla¹,

Hernandez²,

Rodríguez

2015

Journal of Diseases

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Taurodontism is a clinical condition found in the molar teeth of humans whereby the body of the tooth and pulp chamber is enlarged vertically at the expense of the roots. As a result Journal of Diseases 2015 Vol.2, No.2, pp.12-22 ISSN(e): 2410 Contribution/ OriginalityThis study contributes in the existing literature the relation of a well known genetic syndrome as klinefelter, a sexual chromosome alteration (47, XXY) and pediatric patients with taurodontism, an oral situation with teeth roots that grow crookedly with very huge teeth, likened to a bull.

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The chromosomes

Cited by 23 publications

References 1 publication

Chromosome Morphology and Meiosis in Zonocerus Variegatus L. (Orthoptera, Pyrgomorphidae).

Chromosome Morphology and Meiosis in Zonocerus Variegatus L. (Orthoptera, Pyrgomorphidae).

Hemocytes/coelomocytes DNA content in five marine invertebrates: cell cycles and genome sizes

The Importance of Clinical Genotype in Patients with Klinefelter Syndrome. A Genetic Disorder Asociated to Taurodontism

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