(n.) The indirect division of cells in which, prior to division of the cell protoplasm, complicated changes take place in the nucleus, attended with movement of the nuclear fibrils; -- opposed to karyostenosis. The nucleus becomes enlarged and convoluted, and finally the threads are separated into two groups which ultimately become disconnected and constitute the daughter nuclei. Called also mitosis. See Cell development, under Cell.
Example Sentences:
(1) These results indicate a hierarchy of requirements for high pHi during early development of sea urchin embryos, with protein synthesis, karyokinesis, and cytokinesis showing, respectively, increasing requirements for an elevated pHi.
(2) Since we found that PMA-mediated formation of binuclearity was not the effect of cell fusions, it was assumed that the inhibition of cytokinesis preceded by karyokinesis was responsible for binuclearity.
(3) Plant cytokinesis in a particular orientation and location can be viewed as having several component stages, often beginning with the establishment of division polarity before karyokinesis occurs.
(4) We have found that nocodazole reversibly inhibits nuclear migration and can be used to induce karyokinesis before the completion of nuclear migration, resulting in spindles that are displaced toward the hypothecal end of the cell.
(5) Double nucleated cells occur in hypertrophying cells by karyokinesis without subsequent cytokinesis, perhaps in response to the intense protein synthetic demands of normal growth.
(6) The spindle had a broad polar region and did not commence karyokinesis in the first maturation division.
(7) With respect to karyokinesis, mitotic apparatus (MA) structure often was altered when the PI cycle was blocked, and anaphase was blocked when the PI cycle was blocked.
(8) These concentrations of cytochalasin B blocked cytokinesis but not karyokinesis with the result that cells became multinucleate after mitoses.
(9) Despite the ability for karyokinesis, it is concluded that astrocytes do undergo changes with ageing.
(10) These calmodulin-binding proteins may be involved in regulating microtubule organization and depolymerization during karyokinesis.
(11) The spleen was swollen, and the corpuscles and karyokinesis of the cell decreased.
(12) Chromosomes finally entered one blastomere, although they did not participate in the following karyokinesis.
(13) Karyokinesis proceeds to completion under a low pHi, but is retarded, while cytokinesis is always impaired.
(14) We conclude that the mechanism of giant cell DNA amplification involves multiple rounds of DNA replication in the absence of both karyokinesis and cytokinesis, and that sister chromatids, but not homologous chromosomes, remain closely associated during this process.
(15) Similar changes are visible in the contralateral testis which also demonstrates the evolution of multinucleate spermatids by karyokinesis without cytokinesis.
(16) During karyokinesis the nucleolus remained present and divided to form polar masses.
(17) Apparently, the parasite had genetically altered a metabolic pathway necessary for both the initiation of DNA replication and karyokinesis.
(18) Our results would also suggest that activation of gene expression is simply related to neither cell number nor time spent in culture since fertilization, but may be related to continuing karyokinesis.
(19) It starts with synthesis of the new MP a few minutes upon karyokinesis has been completed.
(20) The same dichotomy between the levels of the two decarboxylases was observed for meningiomas, in which ODC levels were higher in atypical forms (with karyokinesis) then in typical forms (without karyokinesis).
Meiosis
Definition:
(n.) Diminution; a species of hyperbole, representing a thing as being less than it really is.
Example Sentences:
(1) To this end, a meiosis-defective mating-type mutation was used as a marker for the plus segment, by taking advantage of its suppressibility by a nonsense suppressor.
(2) When multiple probes were informative, the meiotic exchange points for each meiosis were located in individual families.
(3) This observation suggests that testosterone acts to inhibit meiosis at a site beyond the function of the puromycin-sensitive proteins or that testosterone causes a reduction in the turnover rate of these proteins.
(4) Commitment to meiosis occurs during the prezygotene interval at about the time when S-phase replication is completed.
(5) Meiosis is too complex to have arisen at once full blown and a stepwise scheme is proposed for its evolution, where each step is believed to have provided an immediate selective advantage: (1) The first step in this tentative sequence is the development of a haploidization process by means of a rapid series of mitotic non-disjunctions, turned on under conditions where haploidy is favored.
(6) Recently, cDNA clones encoding several bovine CKI isoforms have been sequenced that show high sequence identity to the HRR25 gene product of the budding yeast Saccharomyces cerevisiae; HRR25 is required for normal cellular growth, nuclear segregation, DNA repair, and meiosis.
(7) They proceed through meiosis normally, as judged by the occurrence of meiotic recombination, the production of haploid nuclei, and the formation of multinucleate cells visible after Giemsa staining.
(8) In continuation of the research on male human meiosis within the study of pachytene bivalents, results from the analysis of 125 cells are presented.
(9) The absence of these mRNAs in mitosis and their disappearance at 4 hr and later in meiosis suggest that the rec7 and rec8 gene products may be involved primarily in the early steps of meiotic recombination in S. pombe.
(10) This trisomy arose through aberrant segregation of translocation chromosome during meiosis in the patient's mother, who is a balanced heterozygote for a complex translocation involving chromosomes 9, 21 and 22.
(11) Chemicals were injected into mice at the MI (meiosis I) stage or 3 hours before the MI stage in order to examine their toxicity.
(12) In the immunogold staining assay a post-fixation and nuclear staining procedure was developed which allowed identification of isolated germ cells, revealing clearly, for all seven MAbs, that the determinants were expressed on germ cells but not on somatic cells and, for WCS 7, 11 and 12 only, that the determinants first appeared on small spermatogonia prior to meiosis.
(13) A 'small' CG-free area of the cortex, with prominent cytoplasmic protrusions, appeared twice during the progression of meiosis.
(14) An attractive explanation for these results is that long tandem arrays of simple repeated sequences are generated at high frequency throughout the genome and that they are retained for a longer time on the Y chromosome due to the absence of homologous pairing at meiosis.
(15) Expression of one of the three genes was found to be limited to a single cell type during the 5-6 day period from late meiosis to immature pollen formation.
(16) Analysis of RNA from different developmental stages and from enriched populations of spermatogenic cells revealed that this gene is expressed during the prophase stage of meiosis.
(17) In fission yeast the ability to undergo meiosis and sporulation is conferred by the matP+ and matM+ genes of the mating-type locus.
(18) The binding of in vivo labeled RNA to the corresponding DNAs increased 3- to 12-fold at the time of meiosis I, in parallel with the accumulation of the SPR transcripts.
(19) It was concluded that meiosis and spore formation in Saccharomycopsis lipolytica seem to represent parallel and coordinated processes which generally resemble those recorded for Saccharomyces cerevisiae and Hansenula species.
(20) Neither meiosis nor mutagenesis increased the revertant frequency, nor did incubation at elevated temperatures lower it.