Cytological basis of 2n pollen formation in a wide range of 2x, 4x, and 6x taxa from tuber-bearing Solanum species

Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 8-13 ◽  
Author(s):  
Kazuo Watanabe ◽  
Stanley J. Peloquin
Keyword(s):  
South America ◽  
Solanum Species ◽  
2N Pollen ◽  
Parallel Spindles ◽  
Wide Range ◽  
Pollen Formation

Cytological mechanisms of 2n pollen formation were investigated in microsporogenesis and sporad development in 2x, 4x, and 6x taxa of tuber-bearing Solanum species that were originally collected from Mexico, and Central and South America. Parallel spindles and tripoles were seen at anaphase II in the majority of genotypes observed. The occurrence of parallel spindles and tripoles were well correlated with the occurrence of dyads and triads at the sporad stage. Further, the frequency of 2n pollen predicted by frequencies of parallel spindles and tripoles and by frequencies of dyads and triads were also well correlated with observed 2n pollen frequencies. Premature cytokinesis at telophase I to prophase II was seen only in 2x and 4x species from series Conicibaccata. The frequency of premature cytokinesis corresponded well with the frequency of dyads leading to 2n pollen formation. It was concluded that the major mechanisms of 2n pollen formation in tuber-bearing Solanum species is parallel spindles.Key words: cytological mechanisms, parallel spindles, ploidy series, tuber-bearing Solanum species, 2n pollen.

2n pollen formation via parallel spindles in the potato cultivar sebago

1980 ◽  
Vol 57 (9) ◽  
pp. 449-455 ◽  
Author(s):  
E. W. Souter ◽  
J. C. Dawe ◽  
S. J. Peloquin
Keyword(s):  
Potato Cultivar ◽  
2N Pollen ◽  
Parallel Spindles ◽  
Pollen Formation

THREE MECHANISMS OF 2n POLLEN FORMATION IN DIPLOID POTATOES

1975 ◽  
Vol 17 (2) ◽  
pp. 217-225 ◽  
Author(s):  
D. W. S. Mok ◽  
S. J. Peloquin
Keyword(s):  
Meiotic Division ◽  
Genetic Data ◽  
The Other ◽  
Cleavage Furrow ◽  
2N Pollen ◽  
Parallel Spindles ◽  
Solatium Tuberosum ◽  
Pollen Formation ◽  
Group Tuberosum

Three mechanisms of 2n pollen formation observed in diploid hybrids between Solatium tuberosum Group Phureja (2x) and haploids of S. tuberosum Group Tuberosum (4x) are termed parallel spindles (ps), premature cytokinesis 1 (pc 1) and premature cytokinesis 2 (pc 2). A II spindles are parallel to each other in many cells of clones producing 2n pollen by ps. A single cleavage furrow follows and forms a dyad which generates two 2n microspores. The other two mechanisms, pc 1 and pc 2, produce 2n pollen by omission of the second meiotic division. Premature cytokinesis 1 (pc 1) involves asynchronized movement of bivalents to and from the M I plate and falling apart of chromatids at T I. A cleavage furrow follows the first meiotic division, no second division occurs and products of meiosis are dyads. Premature cytokinesis 2 (pc 2) exhibits no abnormalities at the first meiotic division. However, cytokinesis occurs prematurely at P II, no second division occurs, and only dyads are formed. Genetic data suggested that these three mechanisms may be controlled by single loci, and are inherited independently as simple recessives.

Diversity and Integration in Private International Law

2019 ◽  
Keyword(s):  
South America ◽  
International Law ◽  
Value Systems ◽  
Private International Law ◽  
Diverse Range ◽  
Cross Border ◽  
Wide Range ◽  
Depth Analysis ◽  
And Shifts ◽  
Substantive Law

This book opens a cross-regional dialogue and shifts the Eurocentric discussion on diversity and integration to a more inclusive engagement with South America in private international law issues. It promotes a contemporary vision of private international law as a discipline enabling legal interconnectivity, with the potential to transcend its disciplinary boundaries to further promote the reality of cross-border integration, with its focus on the ever-increasing cross-border mobility of individuals. Private international law embraces legal diversity and pluralism. Different legal traditions continue to meet, interact and integrate in different forms, at the national, regional and international levels. Different systems of substantive law couple with divergent systems of private international law (designed to accommodate the former in cross-border situations). This complex legal landscape impacts individuals and families in cross-border scenarios, and international commerce broadly conceived. Private international law methodologies and techniques offer means for the coordination of this constellation of legal orders and value systems in cross-border situations. Bringing together world-renowned academics and experienced private international lawyers from a wide range of jurisdictions in Europe and South America, this edited collection focuses on the connective capabilities of private international law in bridging and balancing legal diversity as a corollary for the development of integration. The book provides in-depth analysis of the role of private international law in dealing with legal diversity across a diverse range of topics and jurisdictions.

scholarly journals Coupling between the JULES land-surface scheme and the CCATT-BRAMS atmospheric chemistry model (JULES-CCATT-BRAMS1.0): applications to numerical weather forecasting and the CO<sub>2</sub> budget in South America

2013 ◽  
Vol 6 (1) ◽  
pp. 453-494 ◽  
Author(s):  
D. S. Moreira ◽  
S. R. Freitas ◽  
J. P. Bonatti ◽  
L. M. Mercado ◽  
N. M. É. Rosário ◽  
...  
Keyword(s):  
South America ◽  
Atmospheric Chemistry ◽  
Land Surface ◽  
Amazon Basin ◽  
Mean Squared Error ◽  
Weather Forecasting ◽  
Dew Point ◽  
Surface Model ◽  
Co2 Concentrations ◽  
Wide Range

Abstract. This article presents the development of a new numerical system denominated JULES-CCATT-BRAMS, which resulted from the coupling of the JULES surface model to the CCATT-BRAMS atmospheric chemistry model. The performance of this system in relation to several meteorological variables (wind speed at 10 m, air temperature at 2 m, dew point temperature at 2 m, pressure reduced to mean sea level and 6 h accumulated precipitation) and the CO2 concentration above an extensive area of South America is also presented, focusing on the Amazon basin. The evaluations were conducted for two periods, the wet (March) and dry (September) seasons of 2010. The statistics used to perform the evaluation included bias (BIAS) and root mean squared error (RMSE). The errors were calculated in relation to observations at conventional stations in airports and automatic stations. In addition, CO2 concentrations in the first model level were compared with meteorological tower measurements and vertical CO2 profiles were compared with aircraft data. The results of this study show that the JULES model coupled to CCATT-BRAMS provided a significant gain in performance in the evaluated atmospheric fields relative to those simulated by the LEAF (version 3) surface model originally utilized by CCATT-BRAMS. Simulations of CO2 concentrations in Amazonia and a comparison with observations are also discussed and show that the system presents a gain in performance relative to previous studies. Finally, we discuss a wide range of numerical studies integrating coupled atmospheric, land surface and chemistry processes that could be produced with the system described here. Therefore, this work presents to the scientific community a free tool, with good performance in relation to the observed data and re-analyses, able to produce atmospheric simulations/forecasts at different resolutions, for any period of time and in any region of the globe.

scholarly journals A review on design and testing methodologies of modern freight train draft gear system

2021 ◽  
Author(s):  
Simon Wagner ◽  
Colin Cole ◽  
Maksym Spiryagin
Keyword(s):  
Soviet Union ◽  
South America ◽  
Former Soviet Union ◽  
Rolling Stock ◽  
Freight Train ◽  
Wide Range ◽  
Draft Gear ◽  
Design And Testing ◽  
Damping Systems ◽  
The Eu

AbstractRolling stock connection systems are key to running longer and heavier trains as they provide both the connections of vehicles and the damping, providing the longitudinal suspension of the train. This paper focuses on the evolution of both connection and stiffness damping systems. Focus is on freight rolling stock, but passenger draw gears are also examined. It was found that connection systems have evolved from the buff and chain system used in the pioneer railways of the 1800s to the modern auto-coupler connection systems that are in-service worldwide today. Refined versions of the buff and chain coupling are, however, still in use in the EU, UK, South America and India. A wide range of auto-coupler systems are currently utilised, but the AAR coupler (Janney coupler) remains the most popular. A further variation that persists is the SA3 coupler (improved Wilson coupler) which is an alternative auto-coupler design used mainly throughout the former Soviet Union. Restricting the review to auto-coupler systems allowed the paper to focus on draft gears which revealed polymer, polymer-friction, steel spring-friction, hydraulic draft gears and sliding sill cushioning systems. Along with the single compressive draft gear units balanced and floating plate configurations are also presented. Typical draft gear acceptance standards are presented along with modelling that was included to aid in presentation of the functional characteristics of draft gears.

CYTOLOGY OF 2n POLLEN FORMATION IN DIPLOID ALFALFA, MEDICAGO SATIVA

1979 ◽  
Vol 21 (4) ◽  
pp. 525-530 ◽  
Author(s):  
Nicholi Vorsa ◽  
E. T. Bingham
Keyword(s):  
Medicago Sativa ◽  
Seed Set ◽  
Pollen Grains ◽  
Genetic Constitution ◽  
2N Pollen ◽  
Diploid Parent ◽  
2N Gamete ◽  
Medicago Sativa L ◽  
Pollen Formation ◽  
Mother Cells

Four diploid (2x) clones of alfalfa, Medicago sativa L., which produced good seed set when used as male parents in 4x-2x crosses were selected for study. The 2x clones descended from 2x haploids of cultivated 4x alfalfa. Fertility in the 4x-2x cross was due to the production of pollen with the unreduced chromosome number (2n pollen) from the 2x parent. The cytological mechanism of 2n pollen formation was found to be disorientation of spindles at metaphase II in up to 38% of the pollen mother cells. Thus, both n and 2n pollen were produced by all four diploids examined. Normal spindles at metaphase II were oriented such that they defined the poles of a tetrahedron and resulted in normal tetrads in a tetrahedral arrangement. Disoriented spindles were basically parallel to each other and resulted in formation of dyads and occasionally a triad. Dyads developed into two 2n pollen grains; triads developed into one 2n and two n pollen grains. Since both n and 2n pollen grains are produced by the diploids, they can be maintained as diploids or they can be used as male parents in crosses to tetraploids. The genetic constitution of 2n pollen resulting from parallel spindles is similar to that expected after first division restitution of meiosis and much of the heterozygosity of the diploid parent is conserved in the gametes. The 2n gamete mechanism has potential application in germplasm transfer and in maximizing heterozygosity in tetraploid hybrids.

Chrysomphalus ficus. [Distribution map].

1951 ◽  
Author(s):  
Keyword(s):  
North America ◽  
South America ◽  
Central America ◽  
West Indies ◽  
Pacific Islands ◽  
New Caledonia ◽  
Ryukyu Islands ◽  
Distribution Map ◽  
Society Islands ◽  
Wide Range

Abstract A new distribution map is provided for Chrysomphalus ficus[Chrysomphalus aonidum] Ashm. (aonidum auct.) (Florida Red Scale). Hosts: Citrus; wide range of Mono- and Dicotyledons. Information is given on the geographical distribution in ASIA, China, Formosa, Hong Kong, Kowloon, India, Indonesia, Israel, Malaya, Pakistan, Philippines, Syria, AFRICA, Agaléga Island, Algeria, Anglo-Egyptian Sudan, Egypt, Madagascar, Mauritius, Morocco, Northern Rhodesia, Portuguese East Africa, Seychelles, Southern Rhodesia, Union of South Africa, Zanzibar, AUSTRALASIA AND PACIFIC ISLANDS, Australia, Hawaii, Society Islands, NORTH AMERICA, Mexico, U.S.A., CENTRAL AMERICA and WEST INDIES, Honduras, Panama, West Indies, SOUTH AMERICA, Argentina, Brazil, British Guiana, Chile, Colombia, Paraguay, Uruguay, Venezuela, Pakistan, Philippines, Ryukyu Islands, Saudi Arabia, Singapore, South Yemen, Sri Lanka, Syria, Taiwan, Yemen, AUSTRALASIA and PACIFIC ISLANDS, American Samoa, Australia, New South Wales, Northern Territory, Queensland, Caroline Islands, Fiji, Hawaii, Kiribati, New Caledonia, Ogasawara-shoto, Papua, New Guinea, Society Islands, Tuvalu, Western Samoa, NORTH AMERICA, USA, California, Florida, Mississippi, Texas, Washington D.C., CENTRAL AMERICA and CARIBBEAN, Barbados, Bermuda, Cayman Islands, Cuba, Dominica, Dominican Republic, El Salvador, Guadeloupe, Guatemala, Haiti, Honduras, Jamaica, Martinique, Mexico, Montserrat, Panama, Puerto Rico, St. Lucia, St. Vincent, Trinidad, Virgin Islands, SOUTH AMERICA, Argentina, Brazil, Chile, Colombia, French Guiana, Guyana, Paraguay, Surinam, Uruguay, Venezuela.

Ustilago hypodytes. [Descriptions of Fungi and Bacteria].

1984 ◽  
Author(s):  
J. E. M. Mordue
Keyword(s):  
New Zealand ◽  
North America ◽  
South America ◽  
Root System ◽  
Geographical Distribution ◽  
Host Plants ◽  
Meristematic Tissue ◽  
Wide Range ◽  
Vegetative Multiplication ◽  
Established Infection

Abstract A description is provided for Ustilago hypodytes. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: A wide range of grasses, including species of Agropyron (many), Ammophila, Brachypodium, Bromus, Calamagrostis, Diplachne, Distichlis, Elymus (many), Festuca, Glyceria, Hilaria, Hordeum, Haynaldia, Lygeum, Melica, Orysopsis, Panicum, Phalaris, Phleum, Poa (many), Puccinellia, Secale, Sitanion, Sporobolus, Stipa (many), and Trisetum. DISEASE: Stem smut of grasses. GEOGRAPHICAL DISTRIBUTION: Chiefly a temperate species found in Europe (including Denmark, Finland, France, Germany, Hungary, Italy, Romania, Sweden, Switzerland, UK, USSR, Yugoslavia) and North America (Canada, USA) and extending to central and South America (Argentina, Peru, Uruguay), N. Africa (Libya, Morocco, Tunisia), Japan, Australia and New Zealand. TRANSMISSION: Not fully understood, though inoculation experiments have demonstrated that infection occurs in mature vegetative plants (possibly through meristematic tissue), not seeds or flowers (22, 240; 24, 511). Once established, infection is systemic, probably overwintering in the root system and spreading by vegetative multiplication of host plants as well as from plant to plant (24, 511; 19, 720).

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