A proposal for typical eukaryotic meiosis in microsporidians

1995 ◽  
Vol 41 (1) ◽  
pp. 1-11 ◽  
Author(s):  
T. W. Flegel ◽  
Tirasak Pasharawipas
Keyword(s):  
Dna Content ◽  
Nuclear Dna ◽  
Fat Body ◽  
Nuclear Dna Content ◽  
Original Data ◽  
Life Cycles ◽  
The Other ◽  
Testable Hypothesis ◽  
Developmental Sequences ◽  
Single Sequence

A review of key publications concerning the biology and life cycles of microsporidians has led us to challenge recent proposals that they exhibit a unique process of meiosis when compared with other eukaryotes. The basic data used to support this challenge are the same as those used by researchers suggesting atypical meiosis, but the data are analyzed from a different viewpoint. Arguments are put forward to support a testable hypothesis that meiosis in microsporidians is identical to that which occurs in other eukaryotes. It is proposed that confusion resulted because two separate cytological developmental sequences for diplokaryotic meronts in mosquito fat body cells were previously interpreted as a single sequence. By rearrangement of the original data into two developmental sequences, one abortive and the other for typical meiosis, a better fit was obtained between cytological stages and microphotometric measurements of nuclear DNA content. This improved data fit and the existence of similar nuclear developmental sequences in the fungi are used to support our hypothesis.Key words: microsporidia, meiosis, eukaryotes.

scholarly journals Gigantic Genomes of Salamanders Indicate Body Temperature, not Genome Size, is the Driver of Global Methylation and 5-Methylcytosine Deamination in Vertebrates

2021 ◽  
Author(s):  
Alexander Nichols Adams ◽  
Robert Daniel Denton ◽  
Rachel Lockridge Mueller
Keyword(s):  
Body Temperature ◽  
Transposable Elements ◽  
Genome Size ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Cpg Methylation ◽  
The Other ◽  
Global Methylation ◽  
Cpg Dinucleotide

Methylation of cytosines at CpG dinucleotide sites silences transposable elements (TEs), sequences that replicate and move throughout genomes. TE abundance drives differences in genome size, but TE silencing variation across genomes of different sizes remains largely unexplored. Salamanders include most of the largest C-values -- 9 to 120 Gb. We measured CpG methylation levels in salamanders with genomes ranging from 2N = ~58 Gb to 4N = ~116 Gb. We compared these levels to results from endo- and ectothermic vertebrates with more typical genomes. Salamander methylation levels are ~90%, higher than all endotherms. However, salamander methylation does not differ from the other ectotherms, despite a ~100-fold difference in nuclear DNA content. Because methylation affects the nucleotide compositional landscape through 5-methylcytosine deamination to thymine, we quantified salamander CpG dinucleotide levels and compared them to other vertebrates. Salamanders have comparable CpG levels to other ectotherms, and ectotherm levels are higher than endotherms. These data show no shift in global methylation at the base of salamanders, despite a dramatic increase in TE load and genome size. This result is reconcilable with previous studies by considering endothermy and ectothermy, which may be more important drivers of methylation in vertebrates than genome size.

Mise en évidence de variations saltatoires de l'ADN nucléaire dans et entre les espèces du genre Medicago L.

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 825-834 ◽  
Author(s):  
S. Essad
Keyword(s):  
Medicago Sativa ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
The Other ◽  
Genomic Evolution ◽  
Dna Amount ◽  
Total Amplitude ◽  
Two Samples

Forty-two samples representing 20 Medicago L. species were used to determine the nuclear DNA content of each species. Significant intra- and inter-specific variations were evident. The total amplitude of these variations at the 2C level ranged from 1.6 to 9.4 pg, but the maximum significant DNA evolutionary value amounted to 7.2 pg only (Medicago sativa 4x). The occurrence of two nuclear populations from a number of origins was interpreted as corresponding to a fundamental evolutionary value for one of them and to the addition of metabolic DNA for the other. All the values observed were near multiples of a DNA quantum called a "nucleon," which was estimated to be 0.37 pg at the 2C level. This value corresponds to the lower DNA content observed in Angiosperms. Lastly, it appears that the arithmetical distribution of one nucleon among the usual 2n = 16 chromosomes in the genus ascribes a DNA amount of 0.02 pg to each chromatid, the approximate value for a chromosome modulus.Key words: Medicago, DNA content, nucleon, chromosome modules, saltatory genomic evolution.[Journal translation]

Prognostic value of nuclear DNA content in papillary and follicular thyroid cancer

1988 ◽  
Vol 12 (4) ◽  
pp. 503-507 ◽  
Author(s):  
Jaap F. Hamming ◽  
Lodewijk J. D. M. Schelfhout ◽  
Cees J. Cornelisse ◽  
Cornelis J. H. van de Velde ◽  
Bernard M. Goslings ◽  
...  
Keyword(s):  
Thyroid Cancer ◽  
Dna Content ◽  
Prognostic Value ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Follicular Thyroid Cancer

Estimation of nuclear DNA content by flow cytometry in fishes of the genus Xiphophorus

1989 ◽  
Vol 94 (3) ◽  
pp. 465-468 ◽  
Author(s):  
Terrence R. Tiersch ◽  
Robert W. Chandler ◽  
Klaus D. Kallman ◽  
Stephen S. Wachtel
Keyword(s):  
Flow Cytometry ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content

Changes in chromosome structure, mitotic activity and nuclear DNA content from cells of Allium Test induced by bark water extract of Uncaria tomentosa (Willd.) DC

2006 ◽  
Vol 107 (2) ◽  
pp. 211-221 ◽  
Author(s):  
Mieczysław Kuraś ◽  
Julita Nowakowska ◽  
Elwira Śliwińska ◽  
Radosław Pilarski ◽  
Renata Ilasz ◽  
...  
Keyword(s):  
Mitotic Activity ◽  
Dna Content ◽  
Nuclear Dna ◽  
Chromosome Structure ◽  
Water Extract ◽  
Nuclear Dna Content ◽  
Allium Test ◽  
Uncaria Tomentosa
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