scholarly journals GARDobes: primordial cell nano-precursors with organic catalysis, compositional genome, and capacity to evolve

1999 ◽  
Author(s):  
Daniel Segre ◽  
Dafna Ben-Eli ◽  
Yitzhak Pilpel ◽  
Ora Kedem ◽  
Doron Lancet
Keyword(s):  
Organic Catalysis ◽  
Primordial Cell

TELIOSPORE DEVELOPMENT IN THE PUCCINIASTREAE

1933 ◽  
Vol 9 (5) ◽  
pp. 458-485 ◽  
Author(s):  
S. M. Pady
Keyword(s):  
Epidermal Cells ◽  
The Other ◽  
General Situation ◽  
Thin Walled ◽  
Primordial Cell ◽  
Teliospore Development

The genera that constitute the Pucciniastreae display a wide variation in the type of teliospore produced, as well as in the time and place of production. From the standpoint of development, however, there is a general situation that is common. In all genera primordial cells are formed from enlarged hyphal cells of the mycelium. These give rise to teliospore initials which are in the epidermal cells in Calyptospora, Milesia, Hyalopsora and Thecopsora, and are subepidermal in the other genera. These initials divide to form the mature teliospores, which are thick or thin walled, and few to many-celled. In all cases the teliospore is the product of a single primordial cell.The teliospores of Calyptospora goeppertiana are formed from a perennial mycelium, which causes a witches' broom and hypertrophied stems on species of Vaccinium. The mycelium gives rise to primordial cells in the cortex just below the epidermis. Each primordial cell pierces the host wall above and the contents pass in to form the initial, which by growth and division becomes the teliospore. The mature teliospores are one- to four-celled, with a thickened, dark brown wall. Development is not simultaneous, but progressive, and the teliospores are first formed in the basal parts, moving slowly upward until every cell of the hypertrophied portion of the stem is completely filled. In four species of Milesia the method of development is similar. The spores, however, are thin walled, and are formed in the epidermal cells of the overwintered fronds of their fern hosts. Thecopsora vacciniorum is similar to Milesia in many respects. The teliospores are intra-epidermal, thin walled and multicellular. In Pucciniastrum the teliospores are subepidermal, and arise from primordial cells, as in Calyptospora, Milesia and Thecopsora. The teliospore initials are closely packed, and the mature spores may form extended crusts. The simplest type of development is found in Uredinopsis, which is generally considered to be the most primitive of the fern rusts. Primordial cells are formed in the same way as in the other genera. These round up to form the initials, and cross walls are laid down to give the mature spores.From these studies two possible lines of development are suggested, both beginning with Uredinopsis. One line would lead through the intra-epidermal forms, as Milesia, Calyptospora, etc., and the other through the subepidermal genera, as Pucciniastrum and Melampsoridium.

Insights into the Extraction of Photogenerated Holes from CdSe/CdS Nanorods for Oxidative Organic Catalysis

2021 ◽  
Author(s):  
Yuchen Sha ◽  
Xiao-Min Lin ◽  
Jens Niklas ◽  
Oleg Poluektov ◽  
Benjamin T Diroll ◽  
...  
Keyword(s):  
Oxidative Coupling ◽  
Model Reaction ◽  
Core Shell ◽  
Organic Media ◽  
Cds Nanorods ◽  
Organic Catalysis

Using aerobic oxidative coupling of thiolphenol in organic media as a model reaction, we show that photogenerated holes in CdSe/CdS core-shell nanorods can be efficiently exctracted. As a result, CdSe/CdS...

scholarly journals Contact formation during fibroblast locomotion: involvement of membrane ruffles and microtubules.

1988 ◽  
Vol 106 (3) ◽  
pp. 747-760 ◽  
Author(s):  
G Rinnerthaler ◽  
B Geiger ◽  
J V Small
Keyword(s):  
Actin Filaments ◽  
Leading Edge ◽  
Fiber Assembly ◽  
Contact Formation ◽  
Contact Patterns ◽  
Fluorescence And Electron Microscopy ◽  
Cell Substrate ◽  
History Of ◽  
Cytoskeletal Elements ◽  
Primordial Cell

We have correlated the motility of the leading edge of fibroblasts, monitored by phase-contrast cinematography, with the relative distributions of several cytoskeletal elements (vinculin, tubulin, and actin) as well as with the contact patterns determined by interference reflection microscopy. This analysis has revealed the involvement of both ruffles and microspikes, as well as microtubules in the initiation of focal contact formation. Nascent vinculin sites within the leading edge or at its base, taken as primordial cell-substrate contacts, were invariably colocalized with sites that showed a history of transient, prolonged, or cyclic ruffling activity. Extended microspike structures, often preceded the formation of ruffles. Immunofluorescent labeling indicated that some of these primordial contacts were in close apposition to the ends of microtubules that penetrated into the leading edge. By fluorescence and electron microscopy short bundles of actin filaments found at the base of the leading edge were identified as presumptive, primordial contacts. It is concluded that ruffles and microspikes, either independently or in combination, initiate and mark the sites for future contact. Plaque proteins then accumulate (within 10-30 s) at the contract site and, beneath ruffles, induce localized bundling of actin filaments. We propose that all primordial contacts support traction for leading edge protrusion but that only some persist long enough to nucleate stress fiber assembly. Microtubules are postulated as the elements that select, stabilize, and potentiate the formation of these latter, long-lived contacts.

The Mode of Action of Disulfide Accelerators of Vulcanization

1937 ◽  
Vol 10 (1) ◽  
pp. 158-163
Author(s):  
W. Langenbeck ◽  
H. C. Rhiem
Keyword(s):  
Organic Compounds ◽  
Mode Of Action ◽  
Common Knowledge ◽  
Inorganic Compounds ◽  
Technical Problem ◽  
The Other ◽  
Rubber Industry ◽  
Organic Catalysis ◽  
Catalytic Power ◽  
Organic Catalysts

Abstract The catalytic power of organic compounds in general has up to the present time been studied much less extensively than that of inorganic compounds. For about the last ten years, however, the first author has, in collaboration with a number of his students, attempted to fill this gap, though so far efforts have been confined to explaining the mode of action of natural enzymes by means of comparative experiments with organic catalysts. As a result of this work, a theory based on experimental facts has been developed to explain in a satisfactory way the action of enzymes. The other phase of organic catalysis is, strictly speaking, a technical problem. Why for instance should it not be practicable to utilize organic catalysts more extensively than heretofore in industry? If this problem is to be attacked, it seems reasonable to start with the particular industry which already uses organic catalysts to the greatest extent. This is, of course, the rubber industry. The important accomplishments of the chemical industry with respect to the development of vulcanization accelerators is already common knowledge, and the important task at present is not simply to increase the great number of accelerators already known. A problem of more practical value would seem to be to study the mechanism of the acceleration of vulcanization, about which relatively little has been known heretofore.

The maturation of cell wall structure during germination of Bacillus polymyxa spores

1970 ◽  
Vol 16 (9) ◽  
pp. 883-887 ◽  
Author(s):  
R. G. E. Murray ◽  
Myrtle M. Hall ◽  
J. Marak
Keyword(s):  
Cell Wall ◽  
Intermediate Layer ◽  
Single Layer ◽  
Regular Structure ◽  
Wall Structure ◽  
Bacillus Polymyxa ◽  
Rectangular Array ◽  
Crack Open ◽  
Freeze Etching ◽  
Primordial Cell

Sections of germinating spores of Bacillus polymyxa show that the primordial cell wall consists of a single layer. The intermediate layer and an outer rectangular array of macromolecules found on vegetative cells do not appear until the spore coats crack open about 60 min after initiation of germination. The initial areas of the new components appear in patches under the cracks in the coats. Within 10 min the wall is completed and takes on the profile seen in the vegetative cell. Negative staining and freeze-etching techniques show the regular structure to be identical with that previously shown for mature cells, although the subunits are more readily visible in negatively stained preparations.

Umpolung of Donor-Acceptor Cyclopropanes via N-Heterocyclic Carbene Organic Catalysis

2021 ◽  
Author(s):  
Guihua Nie ◽  
Xuan Huang ◽  
Zhongyao Wang ◽  
Dingwu Pan ◽  
Junmin Zhang ◽  
...  
Keyword(s):  
Organic Catalysis ◽  
Donor Acceptor

A carbene-catalyzed formal umpolung of Donor-Acceptor (D-A) cyclopropanes is disclosed. The cyclopropane moiety is connected to an acetyl aldehyde that can be activated by a carbene catalyst. The initially electrophilic...

Organic Catalysis: A New and Broadly Useful Strategy for Living Polymerization

2003 ◽  
pp. 351-363
Author(s):  
Gregory W. Nyce ◽  
Eric F. Connor ◽  
T. Glauser ◽  
Andreas Möck ◽  
James L. Hedrick
Keyword(s):  
Living Polymerization ◽  
Organic Catalysis
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