CYTOTAXONOMIC STUDIES ON RUMEX SECTION AXILLARES

1958 ◽  
Vol 36 (6) ◽  
pp. 947-996 ◽  
Author(s):  
Nina Marie Sarkar
Keyword(s):  
Pollen Fertility ◽  
Diploid Species ◽  
Taxonomic Revision ◽  
The United States ◽  
Herbarium Specimens ◽  
Tetraploid Species ◽  
Structural Hybridity ◽  
The North ◽  
Essentially Normal ◽  
Very High

The present investigation covers only the North American species of Rumex subgenus Rumex (Lapathum) section Axillares. A review was made of all the previous taxonomical and cytological work done in this group. All the species of the section Axillares were morphologically studied and their natural distribution plotted on maps. The distributional data were derived from about 3000 herbarium specimens gathered from various herbaria in the United States and Canada. Chromosome numbers of 17 taxa of the section Axillares were determined. The three subsections were found to comprise a polyploid series, the monotypic subsection Venosi with 2n = 40, R. verticillatus of the subsection Verticillati with 2n = 60, and all but two of the species studied in the subsection Salicifolii with 2n = 20; the two exceptions were R. mexicanus and R. utahensis, both with 2n = 40. Meiosis was studied in the species of the subsection Salicifolii only. Both the diploid and the tetraploid species showed essentially normal meiotic behavior. Pollen fertility was also very high in all the species. A number of intra- and inter-specific hybridizations were made between the taxa in the subsection Salicifolii, involving both the diploid and the tetraploid species. The resulting diploid (diploid × diploid), triploid (diploid × tetraploid), and tetraploid (tetraploid × tetraploid) F1 hybrids were both morphologically and cytologically studied. Morphologically almost all the diploid and tetraploid hybrids were intermediate between the two parents. The triploid hybrids showed more similarity to the tetraploid species involved in the cross, Meiosis in all the diploid hybrids was essentially normal with 10 bivalents. However, there was a significant decrease in chiasma frequency as compared with the parent species. This was postulated to be due to cryptic structural hybridity. There were three different categories of pollen fertility, ranging from low to very high, which were not correlated with any meiotic irregularities. All the diploid hybrids were fertile and set abundant seeds. Meiosis in the triploid hybrids was very irregular with mostly 10 bivalents and 10 univalents at metaphase I. Anaphases were also irregular, resulting in numerous micronuclei. All the triploid hybrids were sterile and set only a few undeveloped seeds. Meiosis in the tetraploid hybrid studied was also irregular with mostly 9 bivalents and 22 univalents. It was thus postulated that both the tetraploid species are allotetraploids with one genome in common between them and that this genome is essentially the same one shared by the diploid species so far cytologically studied. The tetraploid hybrids were completely sterile and did not set any seed. From the cytogenetic data, the diploid species studied were shown to be very closely interrelated. However, no taxonomic revision was undertaken owing to lack of more complete data involving all the species comprising the group.

scholarly journals Interploid Hybridizations in Ornamental Cherries Using Prunus maackii

2012 ◽  
Vol 30 (2) ◽  
pp. 89-92
Author(s):  
Margaret Pooler ◽  
Hongmei Ma ◽  
David Kidwell-Slak
Keyword(s):  
United States ◽  
Tissue Culture ◽  
Cold Hardiness ◽  
Diploid Species ◽  
Pest Resistance ◽  
The United States ◽  
Tetraploid Species ◽  
Genetic Base ◽  
Flowering Cherry ◽  
New Cultivars

The United States National Arboretum has an ongoing flowering cherry (Prunus) breeding program aimed at broadening the genetic base of cultivated ornamental cherries by developing new cultivars with disease and pest resistance, tolerance to environmental stresses, and superior ornamental characteristics. Interploid crosses, specifically 2X × 4X, in ornamental Prunus would be beneficial in breeding because they could allow introgression of traits not available in the diploid germplasm (pest resistance, cold hardiness), and could result in the creation of seedless triploids that would not set nuisance fruit and possibly have extended bloom durations. This report documents successful hybridization of P. maackii (Manchurian or Amur cherry), a tetraploid species, with P. campanulata, P. ‘Umineko’, and P. maximowiczii, all diploid species. Chromosomes of one of these resulting triploid hybrids were successfully doubled using oryzalin in tissue culture to create a hexaploid plant.

Revisiting the evolution of the North American tetraploid treefrog (Hyla versicolor)

Genome ◽  
2020 ◽  
Vol 63 (11) ◽  
pp. 547-560 ◽  
Author(s):  
James P. Bogart ◽  
Patrick Burgess ◽  
Jinzhong Fu
Keyword(s):  
Diploid Species ◽  
Hyla Versicolor ◽  
Hyla Chrysoscelis ◽  
Gene Exchange ◽  
Tetraploid Species ◽  
Sympatric Populations ◽  
Female Progeny ◽  
The North ◽  
Mating Call ◽  
Mitochondrial Cytochrome B

Hyla chrysoscelis and H. versicolor are common treefrogs in eastern North America and are a cryptic diploid–tetraploid species pair. They are morphologically identical but H. versicolor is a tetraploid. They can be identified acoustically by the male’s advertisement mating call, which has a pulse repetition rate that has twice as many pulses per second in the diploid species, H. chrysoscelis. We used isozymes, microsatellite DNA alleles, and mitochondrial cytochrome b sequences to test the hypothesis that gene exchange occurs between the diploid and tetraploid species in sympatric populations. Each method provided results that are best explained by occasional hybridization of female H. versicolor and male H. chrysoscelis. We propose that H. versicolor first arose from an autotriploid H. chrysoscelis female that produced unreduced triploid eggs. After H. versicolor became established, genes could be passed from H. chrysoscelis to H. versicolor in sympatric populations when these species hybridize. Their F1 female progeny produce unreduced triploid eggs that are fertilized by haploid H. chrysoscelis sperm to reconstitute H. versicolor. Genes can be passed from diploid H. chrysoscelis to tetraploid H. versicolor in sympatric populations.

The origin of Dryopteris campyloptera

1977 ◽  
Vol 55 (10) ◽  
pp. 1419-1428 ◽  
Author(s):  
Mary Gibby
Keyword(s):  
Chromosome Pairing ◽  
North American ◽  
Diploid Species ◽  
Tetraploid Species ◽  
The North ◽  
Independent Origin

In an attempt to establish the origin of the North American tetraploid Dryopteris campyloptera, hybrids have been synthesized and the chromosome pairing at meiosis investigated. It seems probable that it is derived from two diploid species, D. assimilis and D. intermedia. Dryopteris austriaca, a tetraploid species from Europe, is derived from the same diploid species but it may well have had an independent origin.

scholarly journals Cyperaceae in Mexico: Diversity and distribution

2018 ◽  
Vol 96 (2) ◽  
pp. 305 ◽  
Author(s):  
M. Socorro González-Elizondo ◽  
Anton A. Reznicek ◽  
Jorge A. Tena-Flores
Keyword(s):  
Rapid Evolution ◽  
Taxonomic Revision ◽  
Field Work ◽  
The United States ◽  
Herbarium Specimens ◽  
Generic Level ◽  
Holokinetic Chromosomes ◽  
The Family ◽  
Infraspecific Taxa ◽  
High Level

<p><strong>Background</strong>: Cyperaceae, with about 5,500 species and 90 genera worldwide, are the third largest family among Monocots. A unique combination of morphological and karyotypical features, among which stand holokinetic chromosomes, favors a rapid evolution and diversification and a high level of endemism in some groups. Preliminary checklists of Mexican sedges have been published but an updating of the taxonomy and nomenclature of the group for the country is required.</p><p><strong>Questions</strong>: How many and which species and genera of Cyperaceae are in Mexico?, what patterns of geographic distribution display those species?, which are the main gaps in the systematic knowledge in the family?</p><p><strong>Study site and years of study</strong>: Mexico, 1990 to 2016.</p><p><strong>Methods</strong>: A database of Mexican Cyperaceae was generated with basis in literature review, study of herbarium specimens (11 herbaria in Mexico and the United States) and field work, the last mainly focused on <em>Carex</em>. Diversity and endemism level were calculated. Besides, we analyzed in different space scales their distributional range.</p><p><strong>Results</strong>: Our dataset includes 460 species and 20 infraspecific taxa in 21 genera that belong to 10 of the 17 tribes of the family. Subfamily Cyperoideae includes almost 100 % of the Mexican sedges, as only one representative of subfamily Mapanioideae is known for the country. At the generic level, a drastic reduction in number (21) in comparison to previous inventories (27) results of recent phylogenetic and taxonomic rearrangements. The most diverse genera are <em>Carex</em> (138 taxa) and <em>Cyperus</em> (125), followed by <em>Rhynchospora</em> (65) and <em>Eleocharis</em> (57). Sedges in Mexico are found from sea level to above 4,300 m, in all types of vegetation. The highest diversity was found for Chiapas (237 taxa, 52 % of the total) and Veracruz (206 taxa, 45 %), followed by Oaxaca and Jalisco. Two genera (<em>Cypringlea</em> and <em>Karinia</em>) and 111 species or infraspecific taxa are endemic to Mexico (24 %), 43 of them micro-endemic (only known from one state in the country). Endemism increases to 57 % when the biogeographic extension known as Megamexico is included. Forty six names are excluded from the Mexican flora.</p><strong>Conclusions</strong>: Regardless of the addition of taxa and refining of the databases, the checklist presented here is still preliminary. Collection deficiencies and insufficient taxonomic revision for Mexican sedges are reflected in gaps in their knowledge. There are at least 45 undescribed species; including them the richness of Mexican sedges would exceed 500 species. Many complexes of species are in need of taxonomic revision, mainly in <em>Carex</em> but also in<em> Bulbostylis</em>, <em>Cyperus</em>, <em>Eleocharis</em>, <em>Rhynchospora</em> and <em>Scleria</em>. To advance in the inventory and better understanding of the diversity of Mexican Cyperaceae, we propose some research topics to be addressed in the short term.<p> </p>

Preliminary results of the study on the reasons of the Hai Hau erosion phenomenon

2007 ◽  
Vol 29 (3) ◽  
pp. 415-426
Author(s):  
Pham Van Ninh ◽  
Phan Ngoc Vinh ◽  
Nguyen Manh Hung ◽  
Dinh Van Manh
Keyword(s):  
Mathematical Modeling ◽  
Historical Data ◽  
Middle Part ◽  
Red River ◽  
Erosion Process ◽  
Red River Delta ◽  
The North ◽  
Severe Erosion ◽  
North And South ◽  
Very High

Overall the evolution process of the Red River Delta based on the maps and historical data resulted in a fact that before the 20th century all the Nam Dinh coastline was attributed to accumulation. Then started the erosion process at Xuan Thuydistrict and from the period of 1935 - 1965 the most severe erosion was contributed in the stretch from Ha Lan to Hai Trieu, 1965 - 1990 in Hai Chinh - Hai Hoa, 1990 - 2005 in the middle part of Hai Chinh - Hai Thinh (Hai Hau district). The adjoining stretches were suffered from not severe erosion. At the same time, the Ba Lat mouth is advanced to the sea and to the North and South direction by the time with a very high rate.The first task of the mathematical modeling of coastal line evolution of Hai Hau is to evaluate this important historical marked periods e. g. to model the coastal line at the periods before 1900, 1935 - 1965; 1965 - 1990; 1990 - 2005. The tasks is very complicated and time and working labors consuming.In the paper, the primarily results of the above mentioned simulations (as waves, currents, sediments transports and bottom - coastal lines evolution) has been shown. Based on the obtained results, there is a strong correlation between the protrusion magnitude and the southward moving of the erosion areas.

Mafias on the Move

2011 ◽  
Author(s):  
Federico Varese
Keyword(s):  
United States ◽  
New York ◽  
Organized Crime ◽  
The United States ◽  
The West ◽  
Market Expansion ◽  
The North ◽  
Economic Transformations ◽  
At Will

Organized crime is spreading like a global virus as mobs take advantage of open borders to establish local franchises at will. That at least is the fear, inspired by stories of Russian mobsters in New York, Chinese triads in London, and Italian mafias throughout the West. As this book explains, the truth is more complicated. The author has spent years researching mafia groups in Italy, Russia, the United States, and China, and argues that mafiosi often find themselves abroad against their will, rather than through a strategic plan to colonize new territories. Once there, they do not always succeed in establishing themselves. The book spells out the conditions that lead to their long-term success, namely sudden market expansion that is neither exploited by local rivals nor blocked by authorities. Ultimately the inability of the state to govern economic transformations gives mafias their opportunity. In a series of matched comparisons, the book charts the attempts of the Calabrese 'Ndrangheta to move to the north of Italy, and shows how the Sicilian mafia expanded to early twentieth-century New York, but failed around the same time to find a niche in Argentina. The book explains why the Russian mafia failed to penetrate Rome but succeeded in Hungary. A pioneering chapter on China examines the challenges that triads from Taiwan and Hong Kong find in branching out to the mainland. This book is both a compelling read and a sober assessment of the risks posed by globalization and immigration for the spread of mafias.

Die Konstruktion von Natur – Central Park neu besichtigt | The Construction of Nature – Central Park Revisited

2005 ◽  
Vol 156 (8) ◽  
pp. 288-296
Author(s):  
Vittorio Magnago Lampugnani
Keyword(s):  
New York ◽  
Hudson River ◽  
The United States ◽  
Central Park ◽  
Housing Developments ◽  
Hudson River School ◽  
The North ◽  
Man And Nature ◽  
The 19Th Century ◽  
The Relationship

In the first half of the 19th century scientific philosophers in the United States, such as Emerson and Thoreau, began to pursue the relationship between man and nature. Painters from the Hudson River School discovered the rural spaces to the north of New York and began to celebrate the American landscape in their paintings. In many places at this time garden societies were founded, which generated widespread support for the creation of park enclosures While the first such were cemeteries with the character of parks, housing developments on the peripheries of towns were later set in generous park landscapes. However, the centres of the growing American cities also need green spaces and the so-called «park movement»reached a first high point with New York's Central Park. It was not only an experimental field for modern urban elements, but even today is a force of social cohesion.

scholarly journals Progress in Diagnosing Primary Ciliary Dyskinesia: The North American Perspective

Diagnostics ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1278
Author(s):  
Michael Glenn O’Connor ◽  
Amjad Horani ◽  
Adam J. Shapiro
Keyword(s):  
Genetic Testing ◽  
North America ◽  
North American ◽  
Primary Ciliary Dyskinesia ◽  
Clinical Phenotype ◽  
The United States ◽  
Diagnostic Process ◽  
The North ◽  
Diagnostic Guideline ◽  
Ciliary Dyskinesia

Primary Ciliary Dyskinesia (PCD) is a rare, under-recognized disease that affects respiratory ciliary function, resulting in chronic oto-sino-pulmonary disease. The PCD clinical phenotype overlaps with other common respiratory conditions and no single diagnostic test detects all forms of PCD. In 2018, PCD experts collaborated with the American Thoracic Society (ATS) to create a clinical diagnostic guideline for patients across North America, specifically considering the local resources and limitations for PCD diagnosis in the United States and Canada. Nasal nitric oxide (nNO) testing is recommended for first-line testing in patients ≥5 years old with a compatible clinical phenotype; however, all low nNO values require confirmation with genetic testing or ciliary electron micrograph (EM) analysis. Furthermore, these guidelines recognize that not all North American patients have access to nNO testing and isolated genetic testing is appropriate in cases with strong clinical PCD phenotypes. For unresolved diagnostic cases, referral to a PCD Foundation accredited center is recommended. The purpose of this narrative review is to provide insight on the North American PCD diagnostic process, to enhance the understanding of and adherence to current guidelines, and to promote collaboration with diagnostic pathways used outside of North America.

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