scholarly journals DEVELOPMENTAL AND REGULATORY MECHANISMS INVOLVED IN PECAN SOMATIC EMBRYO MATURATION

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1154F-1154 ◽  
Author(s):  
Hazel Y. Wetzstein ◽  
Choong-Suk Kim
Keyword(s):  
Somatic Embryo ◽  
Cold Treatment ◽  
Limiting Factor ◽  
Embryo Maturation ◽  
Electron Microscopic ◽  
Low Frequencies ◽  
Transmission Electron ◽  
Somatic Embryo Conversion ◽  
Somatic Embryogenic

Although somatic embryogenesis in vitro has been carried out successfully in a number of plants, a limiting factor in many somatic embryogenic systems is that plantlet regeneration is not obtainable or restricted to low frequencies. We have developed a repetitive, high frequency somatic embryogenic system in pecan (Carya illinoensis) and have identified effective treatments for improved somatic embryo conversion. A 6 to 10 week cold treatment followed by a 5 day desiccation, promoted enhanced root germination and extension, and epicotyl elongation. Light and transmission electron microscopic evaluations of somatic embryo cotyledon development will be presented and related to conversion enhancing treatments and their possible roles in embryo maturation.

scholarly journals DEVELOPMENTAL AND REGULATORY MECHANISMS INVOLVED IN PECAN SOMATIC EMBRYO MATURATION

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1154f-1154
Author(s):  
Hazel Y. Wetzstein ◽  
Choong-Suk Kim
Keyword(s):  
Somatic Embryo ◽  
Cold Treatment ◽  
Limiting Factor ◽  
Embryo Maturation ◽  
Electron Microscopic ◽  
Low Frequencies ◽  
Transmission Electron ◽  
Somatic Embryo Conversion ◽  
Somatic Embryogenic

Although somatic embryogenesis in vitro has been carried out successfully in a number of plants, a limiting factor in many somatic embryogenic systems is that plantlet regeneration is not obtainable or restricted to low frequencies. We have developed a repetitive, high frequency somatic embryogenic system in pecan (Carya illinoensis) and have identified effective treatments for improved somatic embryo conversion. A 6 to 10 week cold treatment followed by a 5 day desiccation, promoted enhanced root germination and extension, and epicotyl elongation. Light and transmission electron microscopic evaluations of somatic embryo cotyledon development will be presented and related to conversion enhancing treatments and their possible roles in embryo maturation.

Cytological changes induced by platinum-thymine in sarcoma-180 cells: Electron microscopy study

1990 ◽  
Vol 48 (3) ◽  
pp. 290-291
Author(s):  
Gustav Ofosu
Keyword(s):  
Mammalian Cells ◽  
Antitumor Agent ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Limiting Factor ◽  
Sarcoma 180 ◽  
Electron Microscopic ◽  
Cytological Changes

Platinum-thymine has been found to be a potent antitumor agent, which is quite soluble in water, and lack nephrotoxicity as the dose-limiting factor. The drug has been shown to interact with DNA and inhibits DNA, RNA and protein synthesis in mammalian cells in vitro. This investigation was undertaken to elucidate the cytotoxic effects of piatinum-thymine on sarcoma-180 cells in vitro ultrastructurally, Sarcoma-180 tumor bearing mice were treated with intraperitoneal injection of platinum-thymine 40mg/kg. A concentration of 60μg/ml dose of platinum-thymine was used in in vitro experiments. Treatments were at varying time intervals of 3, 7 and 21 days for in vivo experiments, and 30, 60 and 120 min., 6, 12, and 24th in vitro. Controls were not treated with platinum-thymine.Electron microscopic analyses of the treated cells in vivo and in vitro showed drastic cytotoxic effect.

scholarly journals TrkB-Targeted Therapy for Mucoepidermoid Carcinoma

Biomedicines ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 531
Author(s):  
Vivian P. Wagner ◽  
Manoela D. Martins ◽  
Esra Amoura ◽  
Virgilio G. Zanella ◽  
Rafael Roesler ◽  
...  
Keyword(s):  
Cell Migration ◽  
Cell Lines ◽  
Mucoepidermoid Carcinoma ◽  
Combined Treatment ◽  
Cell Ultrastructure ◽  
Ultrastructural Changes ◽  
Migration And Invasion ◽  
Limiting Factor ◽  
Transmission Electron

The brain-derived neurotrophic factor (BDNF)/tyrosine receptor kinase B (TrkB) pathway was previously associated with key oncogenic outcomes in a number of adenocarcinomas. The aim of our study was to determine the role of this pathway in mucoepidermoid carcinoma (MEC). Three MEC cell lines (UM-HMC-2, H253 and H292) were exposed to Cisplatin, the TrkB inhibitor, ANA-12 and a combination of these drugs. Ultrastructural changes were assessed through transmission electron microscopy; scratch and Transwell assays were used to assess migration and invasion; and a clonogenic assay and spheroid-forming assay allowed assessment of survival and percentage of cancer stem cells (CSC). Changes in cell ultrastructure demonstrated Cisplatin cytotoxicity, while the effects of ANA-12 were less pronounced. Both drugs, used individually and in combination, delayed MEC cell migration, invasion and survival. ANA-12 significantly reduced the number of CSC, but the Cisplatin effect was greater, almost eliminating this cell population in all MEC cell lines. Interestingly, the spheroid forming capacity recovered, following the combination therapy, as compared to Cisplatin alone. Our studies allowed us to conclude that the TrkB inhibition, efficiently impaired MEC cell migration, invasion and survival in vitro, however, the decrease in CSC number, following the combined treatment of ANA-12 and Cisplatin, was less than that seen with Cisplatin alone; this represents a limiting factor.

scholarly journals Glial imaging during synapse remodeling at the neuromuscular junction

2008 ◽  
Vol 4 (4) ◽  
pp. 319-326 ◽  
Author(s):  
Yi Zuo ◽  
Derron Bishop
Keyword(s):  
Neuromuscular Junction ◽  
Schwann Cells ◽  
Synapse Formation ◽  
Ultrastructural Organization ◽  
Post Injury ◽  
Electron Microscopic ◽  
Cell Dynamics ◽  
Transmission Electron

Glia are an indispensable structural and functional component of the synapse. They modulate synaptic transmission and also play important roles in synapse formation and maintenance. The vertebrate neuromuscular junction (NMJ) is a classic model synapse. Due to its large size, simplicity and accessibility, the NMJ has contributed greatly to our understanding of synapse development and organization. In the past decade, the NMJ has also emerged as an effective model for studying glia–synapse interactions, in part due to the development of various labeling techniques that permit NMJs and associated Schwann cells (the glia at NMJs) to be visualized in vitro and in vivo. These approaches have demonstrated that Schwann cells are actively involved in synapse remodeling both during early development and in post-injury reinnervation. In vivo imaging has also recently been combined with serial section transmission electron microscopic (ssTEM) reconstruction to directly examine the ultrastructural organization of remodeling NMJs. In this review, we focus on the anatomical studies of Schwann cell dynamics and their roles in formation, maturation and remodeling of vertebrate NMJs using the highest temporal and spatial resolution methods currently available.

Morphometrical Ultrastructural Studies of the Rat's Hepatocytes Under Cooling

1997 ◽  
Vol 3 (S2) ◽  
pp. 245-246
Author(s):  
A.S. Kaprelyants ◽  
A.A. Kaprelyants ◽  
A.N. Reylan ◽  
R.K. Migunova
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscopic ◽  
Rat Hepatocyte ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Morphometric Methods

The aim of given investigation is to study the effect of cooling upon rat hepatocyte structure using transmission electron microscopic and computer morphometric methods. Ultrastructural and morphometrical characteristics of hepatocytes under liver cooling for various levels under in vivo and in vitro conditions were investigated. Vistar rats of 180-250 g were used in the experiment. Liver cooling (in vivo) was performed by means of original cryoapplicator with different probe temperature (1,2). Liver tissue for transmission electron microscopy was fixed in glutaraldehyde fixator on cocadylate buffer and OsO4. Dehydration was completed on acetone (3). Tissue embedding was done into the mixture of Epon/Araldite epoxy rasin. Ultrathin slices were contrasted by the method of Reinolds. Cell viewing and imaging were accomplished by electron microscope at accelerating power of 75kV.Morphometrical and stereometrical analysis was performed using the “Morpho-Tools” original computer system (c) 1994-1996 A.S. Kaprelyants, A.A. Kaprelyants, A.N. Reylan .

Somatic embryo maturation, germination, and soil establishment of plants of black and white spruce (Picea mariana and Picea glauca)

1990 ◽  
Vol 68 (12) ◽  
pp. 2583-2589 ◽  
Author(s):  
S. M. Attree ◽  
T. E. Tautorus ◽  
D. I. Dunstan ◽  
L. C. Fowke
Keyword(s):  
Abscisic Acid ◽  
Somatic Embryo ◽  
Picea Mariana ◽  
Picea Glauca ◽  
Black Spruce ◽  
White Spruce ◽  
Embryo Maturation ◽  
Black And White ◽  
Somatic Embryo Maturation

Somatic embryo maturation, germination, and soil establishment frequencies were compared for two conifer species, white and black spruce (Picea glauca and Picea mariana). The comparison of the two species regenerated and established in soil under the same conditions showed black spruce to be the most responsive. Shorter exposure times to 32 μM abscisic acid were not as effective as maturation on a medium containing 16 μM abscisic acid for 28 days. This gave similar maturation frequencies for the two species (6–8%), and germination frequencies of 64% for white spruce and over 73% for black spruce. Over 1800 black and white spruce plantlets were recovered, and more than 400 were transferred from in vitro to nonsterile conditions. Sixty percent (160) of the black spruce plantlets survived transfer and continued to grow vigorously. By comparison only 18% (29) of the white spruce plantlets survived, and half of these rapidly produced dormant buds and underwent no further shoot growth. White spruce plants that did not produce dormant buds grew vigorously. These results indicate that there are large differences in the ability of these closely related species to respond to plantlet establishment following regeneration from somatic embryos, and that black spruce is highly responsive to micropropagation by this method. Key words: Picea glauca, Picea mariana, somatic embryogenesis, maturation, germination, soil establishment.

Intraerythrocytic schizogony of Theileria annulata

Parasitology ◽  
1985 ◽  
Vol 91 (1) ◽  
pp. 67-82 ◽  
Author(s):  
P. A. Conrad ◽  
B. G. Kelly ◽  
C. G. D. Brown
Keyword(s):  
Theileria Annulata ◽  
Infected Cattle ◽  
Electron Microscopic ◽  
Trophozoite Stage ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies ◽  
Food Vacuoles

The intraerythrocytic multiplication of two strains of Theileria annulata was studied with parasites maintained in stationary cultures and in the blood of infected cattle. In cultures established with blood from infected cattle 20–60% of single T. annulata piroplasms divided into quadruplet forms by day 6 in vitro. Transmission electron microscopic studies of T. annulata in culture showed that piroplasms possess intracytoplasmic food vacuoles and cytostomes during a pre-division trophozoite stage. The onset of intraerythrocytic multi plication was marked by the appearance of rhoptries and electron-dense plaques beneath the parasite's plasmalemmal membrane. The plaques developed into short segments of subplasmalemmal double membranes which were closely associated with the rhoptries. It was concluded that multiplication of T. annulata in erythrocytes occurred by schizogony, as nuclear division preceded cytoplasmic division and the final separation of merozoites. The four merozoites produced by intraerythrocytic schizogony had the same ultrastructural features as the T. annulata merozoites produced by intralymphocytic schizogony. Clusters of four merozoites, identical to those observed in stationary cultures, were also seen in the erythrocytes of persistently infected cattle and appeared to represent the most significant dividing forms of T. annulata in vivo.

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