Genomic differentiation and polyploidy in Sowerbaea (Liliaceae)

1976 ◽  
Vol 24 (3) ◽  
pp. 349 ◽  
Author(s):  
DA Stewart ◽  
BA Barlow
Keyword(s):  
Nuclear Dna ◽  
Early Stage ◽  
Chromosome Length ◽  
Late Tertiary ◽  
Eastern Australia ◽  
Structural Differences ◽  
Basic Genome ◽  
Diploid Level ◽  
Dna Measurements ◽  
Later Phase

Sowerbaea is an endemic Australian genus of five allopatric, vicarious species. A basic genome of three long subacrocentric chromosomes and one shorter acrocentric chromosome is constant in the genus, but within this overall genomic uniformity there are distinct karyotypic differences between species. There are also quantitative differences in nuclear DNA with a twofold difference between the species with the greatest and least amounts of DNA per genome. The quantitative DNA measurements have been combined with measurements of relative chromosome length to obtain estimates of differences in absolute chromosome sizes. Polyploidy is widespread in the genus, and diploid (n = 4), tetraploid (n = 8) and octoploid (n = 16) biotypes occur. Structural differences in the genomes were established at the diploid level, and have arisen during an early stage in differentiation of biotypes in the genus. The polyploid forms are mostly located in eastern Australia, and the establishment of polyploid races was probably a later phase of biotype differentiation associated with late Tertiary and Quaternary climatic changes. The tetraploids are structural autoploids, and have probably arisen within established biotypes. The octoploid form of S. juncea is probably an autoallo-octoploid, derived from tetraploid stocks which were ancestral to S. juncea and S. subtilis respectively.

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.

When is a prognostic factor useful? A guide for the perplexed.

1991 ◽  
Vol 9 (2) ◽  
pp. 348-356 ◽  
Author(s):  
M N Levine ◽  
G P Browman ◽  
M Gent ◽  
R Roberts ◽  
M Goodyear
Keyword(s):  
Breast Cancer ◽  
Nuclear Dna ◽  
Early Stage ◽  
Cancer Recurrence ◽  
Nuclear Dna Content ◽  
Predictive Ability ◽  
Threshold Value ◽  
Prognostic Test ◽  
Risk Patients

Traditionally, a number of variables have been used to predict outcome in patients with early-stage breast cancer. These tests are simple to perform and relatively inexpensive. Recently, a number of new factors, eg, tumor proliferative index, nuclear DNA content, and amplification or overexpression of growth-promoting genes or oncogenes have been identified as potential predictors of outcome in patients with breast cancer. There is now increasing pressure to introduce such tests into routine clinical practice. How does a clinical practitioner identify which test, or group of tests, best predicts adverse outcome and whether any more clinically useful information is provided than with the use of more traditional factors alone? The aim of a prognostic test in breast cancer is to predict which patients are destined to develop a recurrence of cancer and those who are not. The prognostic usefulness of a test can be expressed in terms of relative risk (RR), which is the ratio of the risk of breast cancer recurrence in patients who test positive to the risk in those who test negative. Methodologic guidelines that should be satisfied by a study evaluating the predictive ability of a test include the following: (1) Was an inception cohort assembled? (2) Was the referral pattern described? (3) Were laboratory and clinical outcomes assessed in a blinded fashion? (4) Was complete follow-up achieved? (5) Was adjustment for extraneous prognostic factors carried out? (6) Were appropriate statistical methods used? An approach is suggested to help the clinician choose the test, or combination of tests, likely to discriminate between "high-" and "low-risk" patients in his/her own practice. The decision regarding what particular threshold value (risk) defined by a prognostic test (or series of tests) warrants adjuvant therapy for an individual patient is a complex one but should be based on a clear presentation of the risks and benefits to the patient.

The nature and possible origins of soluble salts in deeply weathered landscapes of eastern Australia

Soil Research ◽  
1979 ◽  
Vol 17 (2) ◽  
pp. 197 ◽  
Author(s):  
RH Gunn ◽  
DP Richardson
Keyword(s):  
Sedimentary Rocks ◽  
Granitic Rocks ◽  
Soluble Salts ◽  
Sea Salts ◽  
Soluble Ions ◽  
Late Tertiary ◽  
Eastern Australia ◽  
Salt Affected Soils ◽  
Hydrologic Conditions

Extensive areas of salt-affected soils in eastern Australia occur on the exposed lower zones of lateritic profiles or in derived materials. Analyses of 96 samples of mottled and pallid zones collected in this study show that they generally contain appreciable soluble salts, predominantly sodium chloride, particularly where they developed in argillaceous sedimentary rocks which underlie about two-thirds of the area, and in some granitic rocks. Analyses of 96 samples of unweathered rocks indicate that some contain moderate to appreciable quantities of sodium and chloride, and it is suggested that these and other soluble ions accumulated in the lower zones as a result of deep weathering in the Mid-Tertiary. Atmospheric accessions of sea salts in rain or dry fallout at present rates account partly for the occurrence of salt-affected soil landscapes in some coastal areas but are unlikely sources of salts far inland. Soils formed in situ on weathered basalt, argillaceous sedimentary and granitic rocks which have been exposed at the surface since the Late Tertiary are not salt-affected, because climatic, topographic and hydrologic conditions are different from those of the Mid-Tertiary and only small volumes of rock are involved.

scholarly journals When forms meet genes: revision of the scleractinian genera Micromussa and Homophyllia (Lobophylliidae) with a description of two new species and one new genus

2016 ◽  
Vol 85 (4) ◽  
pp. 387-422 ◽  
Author(s):  
Roberto Arrigoni ◽  
Francesca Benzoni ◽  
Danwei Huang ◽  
Hironobu Fukami ◽  
Chaolun Allen Chen ◽  
...  
Keyword(s):  
New Genus ◽  
Nuclear Dna ◽  
New Caledonia ◽  
Sequence Data ◽  
Intergenic Spacer ◽  
Taxonomic Revision ◽  
Its Region ◽  
Distinct Species ◽  
Morphological Data ◽  
Eastern Australia

The scleractinian family Lobophylliidae is undergoing a major taxonomic revision thanks to the combination of molecular and morphological data. In this study, we investigate the evolutionary relationships and the macro- and micromorphology of six nominal coral species belonging to two of the nine molecular clades of the Lobophylliidae, clades A and B, and of Symphyllia wilsoni, a lobophylliid species analyzed from a molecular point of view for the first time. Sequence data from mitochondrial DNA (COI and the intergenic spacer between COI and l-rRNA), and nuclear DNA (histone H3 and ITS region) are used to generate robust molecular phylogenies and a median-joining haplotype network. Molecular results are strongly in agreement with detailed observations of gross- and fine-scale morphology of skeletons, leading to the formal revision of the genera Micromussa and Homophyllia and the description of two newly discovered zooxanthellate shallow-water species, Micromussa pacifica sp. nov. Benzoni & Arrigoni and Micromussa indiana sp. nov. Benzoni & Arrigoni, and a new genus, Australophyllia gen. nov. Benzoni & Arrigoni. In particular, Acanthastrea lordhowensis and Montastraea multipunctata are moved into Micromussa, A. hillae is synonymized with A. bowerbanki and is transferred to Homophyllia, and a revised diagnosis for both genera is provided. Micromussa pacifica sp. nov. is described from the Gambier Islands with its distribution spanning New Caledonia and eastern Australia. Despite a superficial resemblance with Homophyllia australis, it has distinctive macroand micromorphological septal features. Micromussa indiana sp. nov., previously identified as M. amakusensis, is here described from the Gulf of Aden and the southern Red Sea as a distinct species that is genetically separated from M. amakusensis and is morphologically distinct from the latter due to its smaller corallite size and lower number of septa. Finally, molecular trees show that S. wilsoni is closely related, but molecularly separated from clades A and B, and, also based on a unique combination of corallite and sub-corallite characters, the species is moved into Australophyllia gen. nov. These findings confirm the need for using both genetic and morphological datasets for the ongoing taxonomic revision of scleractinian corals.

scholarly journals Pliocene Origin, Ice Ages and Postglacial Population Expansion Have Influenced a Panmictic Phylogeography of the European Bee-Eater Merops apiaster

Diversity ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 12 ◽  
Author(s):  
Carina Carneiro de Melo Moura ◽  
Hans-Valentin Bastian ◽  
Anita Bastian ◽  
Erjia Wang ◽  
Xiaojuan Wang ◽  
...  
Keyword(s):  
Genetic Differentiation ◽  
Nuclear Dna ◽  
Bird Species ◽  
Population Expansion ◽  
Genetic Connectivity ◽  
Middle Pleistocene ◽  
Ice Ages ◽  
Breeding Sites ◽  
Late Tertiary ◽  
Merops Apiaster

Oscillations of periods with low and high temperatures during the Quaternary in the northern hemisphere have influenced the genetic composition of birds of the Palearctic. During the last glaciation, ending about 12,000 years ago, a wide area of the northern Palearctic was under lasting ice and, consequently, breeding sites for most bird species were not available. At the same time, a high diversity of habitats was accessible in the subtropical and tropical zones providing breeding grounds and refugia for birds. As a result of long-term climatic oscillations, the migration systems of birds developed. When populations of birds concentrated in refugia during ice ages, genetic differentiation and gene flow between populations from distinct areas was favored. In the present study, we explored the current genetic status of populations of the migratory European bee-eater. We included samples from the entire Palearctic-African distribution range and analyzed them via mitochondrial and nuclear DNA markers. DNA data indicated high genetic connectivity and panmixia between populations from Europe, Asia and Africa. Negative outcomes of Fu’s Fs and Tajima’s D tests point to recent expansion events of the European bee-eater. Speciation of Merops apiaster started during the Pliocene around three million years ago (Mya), with the establishment of haplotype lineages dated to the Middle Pleistocene period circa 0.7 Mya. M. apiaster, which breed in Southern Africa are not distinguished from their European counterparts, indicating a recent separation event. The diversification process of the European bee-eater was influenced by climatic variation during the late Tertiary and Quaternary. Bee-eaters must have repeatedly retracted to refugia in the Mediterranean and subtropical Africa and Asia during ice ages and expanded northwards during warm periods. These processes favored genetic differentiation and repeated lineage mixings, leading to a genetic panmixia, which we still observe today.

Determination of nuclear DNA content in fungi using mithramycin: vegetative diploidy in Armillaria mellea confirmed

1983 ◽  
Vol 29 (9) ◽  
pp. 1179-1183 ◽  
Author(s):  
A. L. Franklin ◽  
W. G. Filion ◽  
J. B. Anderson
Keyword(s):  
Dna Binding ◽  
Aspergillus Nidulans ◽  
Dna Content ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Phytopathogenic Fungus ◽  
Armillaria Mellea ◽  
Dna Measurements

Armillaria mellea, a phytopathogenic fungus, is the only member of the Agaricales (Basidiomycetes) whose fertile vegetative phase in nature is thought to be diploid, rather than dikaryotic. To examine the vegetative ploidy of A. mellea, we used the DNA-binding antibiotic, mithramycin, for fluorometry of in situ nuclear DNA. The measurements of nuclear DNA content indicated that strains derived from single basidiospores of A. mellea were haploid and that strains derived from matings of isolates of single spores were diploid. These data confirm the results of earlier genetic experiments, which show haploidy and diploidy in unmated and mated strains, respectively. Nuclear DNA measurements in known haploid and diploid strains of Aspergillus nidulans confirmed the validity of our protocol.

Genome size and karyotype evolution in Tradescantia section Cymbispatha (Commelinaceae)

Genome ◽  
1990 ◽  
Vol 33 (4) ◽  
pp. 604-610 ◽  
Author(s):  
Ann Kenton ◽  
Andrew Drakeford
Keyword(s):  
Genome Size ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Central American ◽  
South American ◽  
Basic Genome ◽  
C Value ◽  
Robertsonian Fusions ◽  
Karyotype Morphology ◽  
Dna Reduction

Karyotype morphology and nuclear DNA content are compared in species of Tradescantia section Cymbispatha from North and South America. Comparison of DNA amounts confirms the polyploid ancestry previously suggested for several cytotypes and shows that basic genome size has been unaffected by the Robertsonian fusions constituting a major evolutionary change in this group. The 2C-values of Mexican tetraploids are double those of their Central American diploid relative Tradescantia gracillima. The 2C-value of the South American tetraploid T. cymbispatha is comparatively lower as a result of a reduction in the size of some chromosomes. This reduction is most likely to have been achieved by Robertsonian fusions in a hybrid whose parental chromosome sets differed in size. The results provide evidence for selection of ancestral diploids with low C-value as mechanism for reduction of genome size in polyploids.Key words: Tradescantia, genome size, polyploidy, Robertsonian fusion, DNA reduction.

scholarly journals Nanocrystallography measurements of early stage synthetic malaria pigment

2017 ◽  
Vol 50 (5) ◽  
pp. 1533-1540 ◽  
Author(s):  
Ruben A. Dilanian ◽  
Victor Streltsov ◽  
Hannah D. Coughlan ◽  
Harry M. Quiney ◽  
Andrew V. Martin ◽  
...  
Keyword(s):  
Free Electron Laser ◽  
Malaria Parasite ◽  
Early Stage ◽  
Simulation Studies ◽  
X Ray ◽  
Additional Information ◽  
Structural Differences ◽  
Malaria Pigment ◽  
Damage Simulation ◽  
Crystalline Forms

The recent availability of extremely intense, femtosecond X-ray free-electron laser (XFEL) sources has spurred the development of serial femtosecond nanocrystallography (SFX). Here, SFX is used to analyze nanoscale crystals of β-hematin, the synthetic form of hemozoin which is a waste by-product of the malaria parasite. This analysis reveals significant differences in β-hematin data collected during SFX and synchrotron crystallography experiments. To interpret these differences two possibilities are considered: structural differences between the nanocrystal and larger crystalline forms of β-hematin, and radiation damage. Simulation studies show that structural inhomogeneity appears at present to provide a better fit to the experimental data. If confirmed, these observations will have implications for designing compounds that inhibit hemozoin formation and suggest that, for some systems at least, additional information may be gained by comparing structures obtained from nanocrystals and macroscopic crystals of the same molecule.

Sign in / Sign up

Export Citation Format

Share Document