Fine structure of the growing point of the coenocytic alga, Caulerpa sertularioides

1969 ◽  
Vol 47 (10) ◽  
pp. 1599-1603 ◽  
Author(s):  
Arun K. Mishra
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Osmium Tetroxide ◽  
Axial Orientation ◽  
Parallel Orientation ◽  
Wall Formation ◽  
Cytoplasmic Vesicles ◽  
Side Walls

The coenocytic alga Caulerpa sertularioides (Gmelin) Howe was used for the study of the ultrastructure of cell wall and cytoplasm. After ultrasonic maceration and metal shadowing of the cell wall the microfibrils were observed to be random at the tip and parallel for each lamella of the subtip region and the mature portions of rhizome. The microfibrils in the two adjacent lamellae crossed each other at about right angles. The microfibrils of wall trabeculae were parallel to each other and to the long axis of the trabeculae. Fine structure studies of the algal cytoplasm were made using material fixed with glutaraldehyde and osmium tetroxide. The rhizome growing point was studied in detail. A gradient in the differentiation of cytoplasm was observed. The appearance varied from compact, homogeneous cytoplasm in the tip to a reticulate, vacuolate organization in the region farther back. Compartmentation in the cytoplasm was noted in the region immediately behind the compact, homogeneous cytoplasm of the tip region. Numerous smooth-walled vesicles were scattered throughout the growing point of the alga and were observed close to the plasmalemma near the cell wall. Microtubules with axial orientation were observed near the side walls of the alga. These also occurred in parallel orientation with respect to the microfibrils in the trabeculae at the growing points of the latter. The results were discussed with respect to the roles of microtubules and the cytoplasmic vesicles in the process of wall formation.

Structures of the motile cells of Coelomomyces psorophorae and function of the zygote in encystment on a host

1979 ◽  
Vol 57 (9) ◽  
pp. 1021-1035 ◽  
Author(s):  
Linda B. Travland
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Fungal Mycelium ◽  
Cell Wall Formation ◽  
Spore Type ◽  
Aquatic Fungus ◽  
Wall Formation ◽  
Motile Cells ◽  
Culiseta Inornata ◽  
And Function

Coelomomyces psorophorae is an aquatic fungus in the order Blastocladiales. Its motile zoospores and zygote transmit this pathogen to its copepod and mosquito larval hosts, respectively. In copepods, the fungal mycelium gives rise to isogametes, which fuse to form zygotes.The fine structure of the motile cells: zoospore, isogamete, and zygote, is reported. Morphology is compared with spore structure of other fungi in the order, and a model is proposed for a blastocladialian parasitic spore type. Features of this parasitic spore include close mitochondrial–nuclear contact, asymmetrical nucleus, internal axoneme, vestigial kinetosome lacking, and presence of adhesion vesicles.Encystment of zygotes on the cuticle of larvae of the mosquito Culiseta inornata appears to involve secretion of the contents of adhesion vesicles. Subsequent events include cell wall formation and dedifferentiation of specialized zygote structures.

scholarly journals THE FINE STRUCTURE OF DIFFERENTIATING XYLEM ELEMENTS

1965 ◽  
Vol 24 (3) ◽  
pp. 415-431 ◽  
Author(s):  
James Cronshaw ◽  
G. Benjamin Bouck
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Fine Structure ◽  
Secondary Wall ◽  
Osmium Tetroxide ◽  
Light And Electron Microscopy ◽  
Wall Thickening ◽  
Direction Parallel ◽  
Secondary Wall Thickening ◽  
Xylem Elements

Differentiating xylem elements of Avena coleoptiles have been examined by light and electron microscopy. Fixation in 2 per cent phosphate-buffered osmium tetroxide and in 6 per cent glutaraldehyde, followed by 2 per cent osmium tetroxide, revealed details of the cell wall and cytoplasmic fine structure. The localized secondary wall thickening identified the xylem elements and indicated their state of differentiation. These differentiating xylem elements have dense cytoplasmic contents in which the dictyosomes and elements of rough endoplasmic reticulum are especially numerous. Vesicles are associated with the dictyosomes and are found throughout the cytoplasm. In many cases, these vesicles have electron-opaque contents. "Microtubules" are abundant in the peripheral cytoplasm and are always associated with the secondary wall thickenings. These microtubules are oriented in a direction parallel to the microfibrillar direction of the thickenings. Other tubules are frequently found between the cell wall and the plasma membrane. Our results support the view that the morphological association of the "microtubules" with developing cell wall thickenings may have a functional significance, especially with respect to the orientation of the microfibrils. Dictyosomes and endoplasmic reticulum may have a function in some way connected with the synthetic mechanism of cell wall deposition.

The Ultrastructure of Myocardial Cells in Normal and Cardiac Lethal Mutant Mexican Axolotls, (Ambystoma Mexicanum)

1970 ◽  
Vol 28 ◽  
pp. 62-63
Author(s):  
Larry F. Lemanski ◽  
Eldridge M. Bertke ◽  
J. T. Justus
Keyword(s):  
Fine Structure ◽  
Heart Development ◽  
Osmium Tetroxide ◽  
Picric Acid ◽  
Ambystoma Mexicanum ◽  
Recessive Mutation ◽  
Acid Mixture ◽  
Myocardial Cells ◽  
Lethal Mutant ◽  
Mexican Axolotl

A recessive mutation has been recently described in the Mexican Axolotl, Ambystoma mexicanum; in which the heart forms structurally, but does not contract (Humphrey, 1968. Anat. Rec. 160:475). In this study, the fine structure of myocardial cells from normal (+/+; +/c) and cardiac lethal mutant (c/c) embryos at Harrison's stage 40 was compared. The hearts were fixed in a 0.1 M phosphate buffered formaldehyde-glutaraldehyde-picric acid-styphnic acid mixture and were post fixed in 0.1 M s-collidine buffered 1% osmium tetroxide. A detailed study of heart development in normal and mutant embryos from stages 25-46 will be described elsewhere.

Ethylene effects on cambial activity and cell wall formation in hypocotyls of Picea abies seedlings

1991 ◽  
Vol 82 (2) ◽  
pp. 219-224 ◽  
Author(s):  
Barbro S. M. Ingemarsson ◽  
Leif Eklund ◽  
Lennart Eliasson
Keyword(s):  
Cell Wall ◽  
Picea Abies ◽  
Cambial Activity ◽  
Cell Wall Formation ◽  
Wall Formation

Arabidopsis Callose Synthase Gene GSL8 is Required for Cell Wall Formation and Establishment and Maintenance of Quiescent Center

2014 ◽  
Vol 48 (4) ◽  
pp. 389-397
Author(s):  
Liu Lin ◽  
Quan Xianqing ◽  
Zhao Xiaomei ◽  
Huang Lihua ◽  
Feng Shangcai ◽  
...  
Keyword(s):  
Cell Wall ◽  
Quiescent Center ◽  
Cell Wall Formation ◽  
Callose Synthase ◽  
Wall Formation

scholarly journals MYB Transcription Factors and Its Regulation in Secondary Cell Wall Formation and Lignin Biosynthesis during Xylem Development

2021 ◽  
Vol 22 (7) ◽  
pp. 3560
Author(s):  
Ruixue Xiao ◽  
Chong Zhang ◽  
Xiaorui Guo ◽  
Hui Li ◽  
Hai Lu
Keyword(s):  
Cell Wall ◽  
Transcription Factors ◽  
Secondary Wall ◽  
Secondary Cell Wall ◽  
Lignin Biosynthesis ◽  
Cell Wall Formation ◽  
Long Distance ◽  
Secondary Cell Wall Formation ◽  
Myb Transcription Factors ◽  
Wall Formation

The secondary wall is the main part of wood and is composed of cellulose, xylan, lignin, and small amounts of structural proteins and enzymes. Lignin molecules can interact directly or indirectly with cellulose, xylan and other polysaccharide molecules in the cell wall, increasing the mechanical strength and hydrophobicity of plant cells and tissues and facilitating the long-distance transportation of water in plants. MYBs (v-myb avian myeloblastosis viral oncogene homolog) belong to one of the largest superfamilies of transcription factors, the members of which regulate secondary cell-wall formation by promoting/inhibiting the biosynthesis of lignin, cellulose, and xylan. Among them, MYB46 and MYB83, which comprise the second layer of the main switch of secondary cell-wall biosynthesis, coordinate upstream and downstream secondary wall synthesis-related transcription factors. In addition, MYB transcription factors other than MYB46/83, as well as noncoding RNAs, hormones, and other factors, interact with one another to regulate the biosynthesis of the secondary wall. Here, we discuss the biosynthesis of secondary wall, classification and functions of MYB transcription factors and their regulation of lignin polymerization and secondary cell-wall formation during wood formation.

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