Secondary origin, hybridization and sexual reproduction in a diploid–tetraploid contact zone of the facultatively apomictic orchid Zygopetalum mackayi

Plant Biology ◽  
2020 ◽  
Vol 22 (5) ◽  
pp. 939-948
Author(s):  
Y. A. Moura ◽  
A. Alves‐Pereira ◽  
C. C. da Silva ◽  
L. M. Souza ◽  
A. P. de Souza ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Contact Zone ◽  
Secondary Origin

The ultrastructure of sexual reproduction in Pythium acanthicum

1976 ◽  
Vol 54 (19) ◽  
pp. 2193-2203 ◽  
Author(s):  
R. H. Haskins ◽  
J. A. Brushaber ◽  
J. J. Child ◽  
L. B. Holtby
Keyword(s):  
Endoplasmic Reticulum ◽  
Sexual Reproduction ◽  
Contact Zone ◽  
Periplasmic Space ◽  
Spine Development ◽  
Storage Body ◽  
Cytoplasmic Ribosomes ◽  
Pythium Acanthicum ◽  
Hyphal Tip

The young oogonium and young antheridium in Pythium acanthicum Drechsler are densely and randomly packed with numerous mitochondria, dictyosomes, nuclei, interlocking vacuoles of several types, some of which contain a dense storage body, a variety of vesicles, endoplasmic reticulum, and cytoplasmic ribosomes. Wall vesicles, evenly distributed next to the plasma-lemma in rapidly growing oogonia, become localized in groups at points where they appear to initiate the hyphal tip-like development of the oogonial spines. They are also found on both sides of the antheridium−oogonium contact zone. Spine development starts shortly after antheridium−oogonial contact is made and ceases with entry of antheridial material into the oogonium. Excess nuclei, mitochondria, and various organelles are abandoned in the periplasmic space, where they normally quickly disintegrate when the oospore is formed. The periplasmic space is invaded frequently by vegetative hyphae originating outside of the oogonium.

Life cycle of Spirogyra decimina var. juergensii (Kütz.) O.V. Petlovany from Lake Baikal

2018 ◽  
pp. 1-7
Author(s):  
Ekaterina A. Volkova
Keyword(s):  
Life Cycle ◽  
Sexual Reproduction ◽  
Lake Baikal

Identification of Spirogyra species is based on the morphology of the fertile specimens. This work provides characteristics of growth and the time of reproduction of Spirogyra decimina var. juergensii in Lake Baikal and describes sexual reproduction and conditions for germination of new filaments of this species isolated from the lake.

Sexual Reproduction of a Red Tide Dinoflagellate Gymnodinium mikimotoi

1994 ◽  
Vol 60 (1) ◽  
pp. 125-126 ◽  
Author(s):  
Akira Ouchi ◽  
Satoshi Aida ◽  
Takuji Uchida ◽  
Tsuneo Honjo
Keyword(s):  
Sexual Reproduction ◽  
Red Tide

Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition Part IV: Laboratory Measurement of Mechanical Properties and Mechanical Actions of Tires Relating to Treadwear

1986 ◽  
Vol 14 (4) ◽  
pp. 264-291
Author(s):  
K. L. Oblizajek ◽  
A. G. Veith
Keyword(s):  
Mechanical Properties ◽  
Shear Stress ◽  
Contact Zone ◽  
Flexural Rigidity ◽  
Comprehensive Evaluation ◽  
Shear Stiffness ◽  
Shear Stresses ◽  
Lateral Shear ◽  
Band Bending ◽  
Tread Rubber

Abstract Treadwear is explained by specific mechanical properties and actions of tires. Rubber shear stresses in the contact zone between the tire and the road become large at large slip angles. When normal stresses are insufficient to prevent sliding at the rear of the footprint, wear occurs at a rate that depends on test severity. Two experimental approaches are described to relate treadwear to tire characteristics. The first uses transducers imbedded in a simulated road surface to obtain direct measurements of contact stresses on the loaded, freely-rolling, steered tires. The second approach is developed with the aid of a simple carcass, tread-band, tread-rubber tire model. Various tire structural configurations; characterized by carcass spring rate, edgewise flexural band stiffness, and tread rubber shear stiffness; are simulated and lateral shear stress response in the contact zone is determined. Tires featuring high band stiffness and low carcass stiffness generate lower lateral shear stress levels. Furthermore, coupling of tread-rubber stiffness and band flexural rigidity are important in determining level of shear stresses. Laboratory measurements with the described apparatus produced values of tread-band bending and carcass lateral stiffness for several tire constructions. Good correlation is shown between treadwear and a broad range of tire stiffness and test course severities.

Stibnite vein from Dębowina near Bardo (polish Sudetes)

2013 ◽  
Vol 2 (1) ◽  
pp. 28-33
Author(s):  
Piotr Kotula
Keyword(s):  
Contact Zone

Abstract In the contact zone of the Bardo Structure and Kłodzko-Złoty Stok Intrusion and Kłodzko Metamorphic, metasomatic orebearing quartz-carbonate veins rich in Sb, Zn, Cu, Ag, Au, Pb are present. In 1771 the mine ,,Reiche Silber Gluck” within stibnite vein was founded in Dębowina near Bardo. Its entrance was discovered again in 2007. The stibnite vein is mainly build of stibnite and sphalerite and of quartz and dolomite rich in Mn. Stibnite crystallizes as columnar or forming radiate centres and aciculars. Its crystals reach size to 2 mm. Sphalerite appears as individual anhedral and polymineralic grained concentrations reaching size to 2,5 mm. Earlier pyrite and arsenopyrite crystallized - they occur locally in this deposit. There were found also in the deposit tetrahedrite rich in Ag, what wasn't reported earlier in studies from the mine in Dębowina.

Definitions and concepts of reproductive biology of diatoms (terminological glossary)

2017 ◽  
Vol 51 ◽  
pp. 71-105 ◽  
Author(s):  
N. A. Davidovich
Keyword(s):  
Mating System ◽  
Sexual Reproduction ◽  
Reproductive Biology ◽  
World Literature ◽  
Russian Literature ◽  
Life Cycles ◽  
Transfer Of Knowledge ◽  
Research Experience ◽  
Key Terms

The absence of a conceptual terminology, sufficiently developed and widely accepted in the Russian literature, significantly hinders progress in the field of reproductive biology of diatoms, restricts communication and debate, prevents training and transfer of knowledge. The present work is an attempt, based on world literature and our own research experience, to summarize, systematize, add, and clarify the existing terms, concepts and definitions related to research which are focused on sex and sexual reproduction in diatoms. A glossary of key terms (more than 200, including synonyms) is provided. Terms refer to diatom reproductive biology, life cycles, fertilization, mating system, gender (including inheritance and determination of sex, as well as inheritance associated with sex). Contradictions between possible interpretations of certain terms are briefly discussed.

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