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]

B-chromosome and C-band heterochromatin variation in Arizona maize populations adapted to different altitudes

Genome ◽  
1990 ◽  
Vol 33 (5) ◽  
pp. 659-662 ◽  
Author(s):  
H. L. Porter ◽  
A. Lane Rayburn
Keyword(s):  
Dna Sequences ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
B Chromosome ◽  
Chromosomal Dna ◽  
Dna Amount ◽  
Maize Populations ◽  
Dna Content Variation ◽  
Band Number

The B-chromosome and C-band numbers were determined in 12 Arizona Indian maize populations. These populations were originally collected from altitudes ranging from 100 to 5300 ft (1 ft = 0.3048 m). In addition, the total nuclear DNA amounts of these populations have been observed to vary by as much as 20%. The number of B-chromosomes was not significantly correlated with altitude, C-band number, or nuclear DNA amount. C-band number was significantly correlated with both altitude and genome size. It does not appear that the amount of C-band variation can account for the large nuclear DNA variation observed in these accessions. Additional A-chromosomal DNA sequences may be involved in the nuclear DNA content variation that exists among these accessions.Key words: heterochromatin, DNA content, evolution, repeated DNA.

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.

scholarly journals NUCLEAR DNA CONTENT IN BLUEBERRY DETERMINED BY FLOW CYTOMETRY

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 580e-580
Author(s):  
Rodomiro Ortiz ◽  
D.E. Costich ◽  
T.P. Meagher ◽  
N. Vorsa
Keyword(s):  
Flow Cytometry ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Haploid Genome ◽  
Dna Flow Cytometry ◽  
Dna Amount ◽  
Ploidy Levels ◽  
Polyploid Evolution ◽  
Haploid Genome Size

DNA flow cytometry was used to determine nuclear DNA content in diploid blueberry species, and 3x, 4x, 5x, and 6x ploidy levels. Relative fluorescence intensity of stained nuclei measured by flow cytometry was a function of the number of chromosome sets (X): Y = 3.7X – 2.3 (r2 = 95.1%). DNA flow cytometry should be useful for ploidy level determination in the seedling stage. A significant linear relationship was established between nuclear DNA content and number of chromosomes (x); DNA (pg) = 0.52 x1 (r2 = 99.8%). Based on this equation the haploid genome DNA amount (1C) was calculated as 0.62 ± 0.08 pg, with an approximate haploid genome size of 602 Mbp/1C. The results indicate that conventional polyploid evolution occured in the section Cyanococcus, genus Vaccinium: the increase in DNA was concurrent with increase in chromosome number. DNA content differences among 2x species were correlated with Nei's genetic distance estimates based on 20 isozyme markers. Most of the variation was among species (49%), with 26% between populations within species, and 25% within populations.

Genome size and genome evolution in diploid Triticeae species

Genome ◽  
2007 ◽  
Vol 50 (11) ◽  
pp. 1029-1037 ◽  
Author(s):  
T. Eilam ◽  
Y. Anikster ◽  
E. Millet ◽  
J. Manisterski ◽  
O. Sagi-Assif ◽  
...  
Keyword(s):  
Genome Size ◽  
Intraspecific Variation ◽  
Dna Content ◽  
Nuclear Dna ◽  
Diploid Species ◽  
Nuclear Dna Content ◽  
Dna Amount ◽  
Nuclear Dna Amount ◽  
Speciation Event ◽  
Close Temporal Proximity

One of the intriguing issues concerning the dynamics of plant genomes is the occurrence of intraspecific variation in nuclear DNA amount. The aim of this work was to assess the ranges of intraspecific, interspecific, and intergeneric variation in nuclear DNA content of diploid species of the tribe Triticeae (Poaceae) and to examine the relation between life form or habitat and genome size. Altogether, 438 plants representing 272 lines that belong to 22 species were analyzed. Nuclear DNA content was estimated by flow cytometry. Very small intraspecific variation in DNA amount was found between lines of Triticeae diploid species collected from different habitats or between different morphs. In contrast to the constancy in nuclear DNA amount at the intraspecific level, there are significant differences in genome size between the various diploid species. Within the genus Aegilops , the 1C DNA amount ranged from 4.84 pg in A. caudata to 7.52 pg in A. sharonensis; among genera, the 1C DNA amount ranged from 4.18 pg in Heteranthelium piliferum to 9.45 pg in Secale montanum . No evidence was found for a smaller genome size in annual, self-pollinating species relative to perennial, cross-pollinating ones. Diploids that grow in the southern part of the group’s distribution have larger genomes than those growing in other parts of the distribution. The contrast between the low variation at the intraspecific level and the high variation at the interspecific one suggests that changes in genome size originated in close temporal proximity to the speciation event, i.e., before, during, or immediately after it. The possible effects of sudden changes in genome size on speciation processes are discussed.

scholarly journals ‘Junk’ DNA and phenotypic evolution in Silene section Siphonomorpha

2008 ◽  
Vol 90 (1) ◽  
pp. 111-118 ◽  
Author(s):  
THOMAS R. MEAGHER ◽  
DENISE E. COSTICH
Keyword(s):  
Negative Correlation ◽  
Sex Chromosomes ◽  
Dna Content ◽  
Nuclear Dna ◽  
Size Variation ◽  
Nuclear Dna Content ◽  
Flower Size ◽  
Phenotypic Evolution ◽  
Genomic Evolution ◽  
Dioecious Species

SummaryOne of the long-standing mysteries in genomic evolution is the observation that much of the genome is composed of repetitive DNA, resulting in inter- and intraspecific variation in nuclear DNA content. Our discovery of a negative correlation between nuclear DNA content and flower size in Silene latifolia has been supported by our subsequent investigation of changes in DNA content as a correlated response to selection on flower size. Moreover, we have observed a similar trend across a range of related dioecious species in Silene sect. Elisanthe. Given the presence of sex chromosomes in dioecious Silene species, and the tendency of sex chromosomes to accumulate repetitive DNA, it seems plausible that dioecious species undergo genomic evolution in ways that differ from what one might expect in hermaphroditic species. Specifically, we query whether the observed relationship between nuclear DNA content and flower size observed in dioecious Silene is a peculiarity of sex chromosome evolution. In the present study we investigated nuclear DNA content and flower size variation in hermaphroditic species of Silene sect. Siphonomorpha, as close relatives of the dioecious species studied previously. Although the nuclear DNA contents of these species were lower than those for species in sect. Elisanthe, there was still significant intra- as well as interspecific variation in nuclear DNA content. Flower size variation was found among species of sect. Siphonomorpha for petal claw and petal limb lengths, but not for calyx diameter. This last trait varies extensively in sect. Elisanthe, in part due to sex-specific selection. A negative correlation with nuclear DNA content was found across populations for petal limb length, but not for other floral dimensions. We conclude that impacts of nuclear DNA content on phenotypic evolution do manifest themselves in hermaphroditic species, so that the effects observed in sect. Elisanthe, and particularly in S. latifolia, while perhaps amplified by the genomic impacts of sex chromosomes, are not limited to dioecious taxa.

Nuclear DNA content in the Australian Bulbine (Liliaceae)

Genome ◽  
1987 ◽  
Vol 29 (2) ◽  
pp. 225-234 ◽  
Author(s):  
E. M. Watson
Keyword(s):  
Key Words ◽  
Genome Evolution ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Clinal Variation ◽  
Dna Amount ◽  
Climatic Trends ◽  
Eastern Australia ◽  
Dna Measurements

Nuclear DNA measurements for 17 Australian populations of Bulbine support the recognition of the four major groups already suggested by chromosome studies. Within the perennial group, Bulbine bulbosa s. lat., the tuberless, 46-chromosome (hypo-8x) "rock lily" has a similar DNA content to the hypo-4x, 24-chromosome populations of the "bulbosa" complex, which has populations at hypo-4x, -8x, and -12x levels. The "rock lily" also has substantially less DNA than another 46-chromosome entity, represented by the Kroombit population. Within the annual group, Bulbine semibarbata s. lat., the distinctions are less clear. However, the winged-seeded, 4x, 28-chromosome "alata" appears to have slightly more DNA than the closely related 26-chromosome "semibarbata." The 54-chromosome, 8x annual populations of eastern Australia have a DNA amount consistent with their proposed allopolyploid origin. The 52-chromosome "semibarbata" populations of Western Australia have, as expected, a lower DNA content than the 54-chromosome form and approximately twice the 4x "semibarbata" amount. It is suggested that some observed clinal variation in DNA content and an apparent DNA deficit in some of the higher polyploids of both perennial and annual groups may be attributable to climatic trends since the Miocene. Key words: Liliaceae, Bulbine, DNA content, polyploids, genome evolution.

scholarly journals Nuclear DNA Content and Ploidy Level of Apple Cultivars Including Polish ones in Relation to Some Morphological Traits

2016 ◽  
Vol 58 (1) ◽  
pp. 81-93 ◽  
Author(s):  
Małgorzata Podwyszyńska ◽  
Dorota Kruczyńska ◽  
Aleksandra Machlańska ◽  
Barbara Dyki ◽  
Iwona Sowik
Keyword(s):  
Chromosome Number ◽  
Flowering Time ◽  
Ploidy Level ◽  
Dna Content ◽  
Nuclear Dna ◽  
Pollen Viability ◽  
Nuclear Dna Content ◽  
Pollen Grain ◽  
Clear Correlation ◽  
Dna Amount

Abstract Apple species and cultivars differ in nuclear (2C) DNA content and ploidy level. The majority of these genotypes are diploids, but there are some triploids and a few tetraploids. Nuclear DNA content is a specific feature and its flow cytometric evaluation can be helpful in differentiating taxa. For many apple genotypes – including all the Polish ones, these characteristics are not known. 2C DNA was evaluated in relation to leaf, flower, fruit, pollen grain and stomata sizes as well as to the flowering time for seventy genotypes (including 46 Polish cultivars) gathered in the gene bank of the Research Institute of Horticulture, Skierniewice, Poland. For standard cultivars with the known chromosome number, 2C value was 1.71 pg for diploid cultivar ‘Alwa’ (2n=2x=34), 2.55 pg for triploid ‘Boskoop’ (3x=51), and 3.37 pg for tetraploid genome (4x=68) of mixoploid ‘McIntosh 2x+4x’. In 61 cultivars (including 41 Polish ones), the nuclear DNA content ranged from 1.58 to 1.78 pg indicating their diploid chromosome number. Five cultivars were identified as triploids (‘Bursztówka Polska’, ‘Pagacz’, ‘Rapa Zielona’, ‘Rarytas Śląski’ and ‘Witos’) owing to their nuclear DNA amount ranging between 2.42 and 2.58 pg. Leaf, flower, fruit, stomata and pollen grain sizes were on average significantly larger in triploids. Thus, in 3x plants the mean leaf surface was 49.1 cm2, flower diameter – 52.4 mm, fruit weight – 204.7 g, stomata length – 32.1 μm and pollen grain diameter – 33.7 μm, whereas in diploids – 36.0 cm2, 46.1 mm, 162.7 g, 28.4 μm and 30.7 μm, respectively. Pollen grain viability was on average significantly higher in diploids (75.6%), compared to triploids (22%). These results confirm that in apple, as in many other plant species, the higher ploidy level of triploids is generally associated with increased sizes of pollen grains, stomata, flowers, fruits and leaves but decreased pollen viability. No clear correlation between ploidy level and flowering time was found. In the case of mixoploid apple genotypes possessing diploid and tetraploid genomes, some phenotype observation is helpful in describing the ploidy level of the histogenic layers, L1 and L2. Small stomata sizes (similar to diploid) indicate diploid L1 and larger leaf sizes, compared to diploid counterparts, show tetraploid L2. The results will be used for breeding, in which it is important to determine maternal and paternal genotypes as well as the direction of the crossing that is of great importance in obtaining seeds and materials for further selection.

scholarly journals Use of Flow Cytometric Measurement of Nuclear DNA Content to Assess Ploidy Level in Azalea

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 627b-627
Author(s):  
Peter H. Velguth ◽  
Harold Pellett
Keyword(s):  
Ploidy Level ◽  
Dna Content ◽  
Nuclear Dna ◽  
Diploid Species ◽  
Nuclear Dna Content ◽  
Chromosome Counts ◽  
Dna Amount ◽  
The North ◽  
Flow Cytometric ◽  
Flow Cytometric Measurement

We evaluated flow cytometric measurement of nuclear DNA content to determine ploidy level in azalea. If ploidy level correlates with DNA content, ploidy level could be determined more readily than by direct chromosome counts and assist in planning crosses and evaluating progeny. Tested plants included azalea cultivars, materials from the azalea breeding project at the Univ. of Minnesota, and species from the Rhododendron Species Botanic Garden and the North Carolina Arboretum. Data compiled from DNA assays of practically all material analyzed fell into distinct groups consistent with their being either diploid, triploid, or tetraploid. Additionally, a known diploid plant of each of four diploid species, together with a natural or derived tetraploid plant of each of these species was obtained. Results showed that the four diploids had a similar DNA content compared to one another. DNA content of the tetraploids was also similar, and the tetraploid's DNA content was approximately twice that of the diploids, as expected. Unfortunately, success with direct chromosome counts in other material has proven elusive, currently precluding direct correlation of DNA amount with ploidy level across other species and cultivars. Although many cases exist in the literature where DNA content has a direct relationship to ploidy level, this does not always hold. Although the majority of plants tested fell into a diploid, triploid, or tetraploid grouping based on DNA content, further study is required to determine the exact relationship between ploidy level and DNA content in azalea.

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.

Genome size in 21 Artemisia L. species (Asteraceae, Anthemideae): Systematic, evolutionary, and ecological implications

Genome ◽  
2001 ◽  
Vol 44 (2) ◽  
pp. 231-238 ◽  
Author(s):  
Montserrat Torrell ◽  
Joan Vallès
Keyword(s):  
Flow Cytometry ◽  
Genome Size ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Life Forms ◽  
Dna Amount ◽  
Ploidy Levels ◽  
Ecological Selection ◽  
Ecological Implications

Genome size was estimated by flow cytometry in 24 populations belonging to 22 Artemisia taxa (21 species, 1 with two subspecies), which represent the distinct subgenera, life forms, basic chromosome numbers, and ploidy levels in the genus. 2C nuclear DNA content values range from 3.5 to 25.65 pg, which represents a more than sevenfold variation. DNA content per haploid genome ranges from 1.75 to 5.76 pg. DNA amount is very well correlated with karyotype length and ploidy level. Some variations in genome size have systematic and evolutionary implications, whereas others are linked to ecological selection pressures.Key words: Artemisia, Asteraceae, flow cytometry, genome size, nuclear DNA amount variation, systematics, evolution, ecology.

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