Variation in pollen wall ultrastructure in New World Senecioneae (Asteraceae), with special reference to Packera

1997 ◽  
Vol 75 (5) ◽  
pp. 730-735 ◽  
Author(s):  
J. F. Bain ◽  
B. S. Tyson ◽  
D. F. Bray
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chromosome Number ◽  
Special Reference ◽  
New World ◽  
Pollen Wall ◽  
Wall Structure ◽  
Transmission Electron ◽  
Wall Ultrastructure ◽  
Base Chromosome Number

The structure of the pollen wall as revealed by transmission electron microscopy is presented for 34 species representing two subtribes and 12 genera of New World Senecioneae. The genus Packera (=aureoid Senecio), with the exception of Packera zimapanica, is characterized by the helianthoid wall structure. In light of these results, the disposition of the latter species requires review. The genera Robinsonecio and Telanthophora of the subtribe Tussilagininae also possess helianthoid pollen. All other taxa surveyed have senecioid pollen. So far as known no taxa exist within the tribe Senecioneae with a base chromosome number of n = 20 and helianthoid pollen. This suggests that the evolution of Packera may have involved hybridization between members of the two subtribes Senecionineae and Tussilagininae. Key words: Asteraceae, Packera, Senecioneae, pollen, TEM, systematics.

scholarly journals Chemical composition, anatomy, lignin distribution, and cell wall structure of Malaysian plant waste fibers

BioResources ◽  
2006 ◽  
Vol 1 (2) ◽  
pp. 220-232 ◽  
Author(s):  
H. P. S. Abdul Khalil ◽  
M. Siti Alwani ◽  
A. K. Mohd Omar
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Chemical Composition ◽  
Cell Wall Structure ◽  
Wall Structure ◽  
Anatomical Characteristics ◽  
Lignin Distribution ◽  
Transmission Electron ◽  
Palm Frond

The chemical composition, anatomical characteristics, lignin distribution, and cell wall structure of oil palm frond (OPF), coconut (COIR), pine-apple leaf (PALF), and banana stem (BS) fibers were analyzed. The chemical composition of fiber was analyzed according to TAPPI Methods. Light microscopy (LM) and transmission electron microscopy (TEM) were used to observe and determine the cell wall structure and lignin distribution of various agro-waste fibers. The results revealed differences in anatomical characteristics, lignin distributions, and cell wall structure of the different types of fibers investigated. Nevertheless, transmission electron microscopy (TEM) micrographs have confirmed that the well wall structure, in each case, could be described in terms of a classical cell wall structure, consisting of primary (P) and secondary (S 1 , S 2 , and S 3 ) layers.

Centromere structure and chromosome number in mitosis of the colourless phytoflagellate Polytoma papillatum (Chlorophyceae, Volvocales, Chlamydomonadaceae)

Genome ◽  
1995 ◽  
Vol 38 (6) ◽  
pp. 1249-1254 ◽  
Author(s):  
Klaus Werner Wolf
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chromosome Number ◽  
Higher Plants ◽  
Attachment Site ◽  
Dense Layer ◽  
Mitotic Metaphase ◽  
Serial Sections ◽  
Transmission Electron ◽  
Alternative Approach

Centromere structure is described in mitosis of the unicellular biflagellate alga Polytoma papillatum using transmission electron microscopy. The kinetochores are five-layered elements at the poleward surface of the chromosomes. The five layers consist of three dense plates interspersed by two transparent zones. The polemost dense layer serves as the attachment site for kinetochore microtubules and the innermost dense layer is intimately associated with the chromatin. The five-layered organization of the kinetochore in the alga is unusual. In animals, three-layered kinetochores are the rule. This type has also been found in some algae, while higher plants do not possess striated kinetochores. An attempt was made to determine the chromosome number of P. papillatum. Individual chromosomes could not be recognized with confidence, since there were numerous lateral contacts between the chromosomes throughout mitosis. An alternative approach, however, was successful. Counting the kinetochores in serial sections through mitotic metaphase and anaphase plates revealed a number of 15 chromosomes.Key words: anaphase, kinetochore, metaphase, microtubule.

scholarly journals ULTRASTRUCTURE AND CHARACTERISTICS OF A DEEP-SEA BACTERIUM

2004 ◽  
Vol 42 (2) ◽  
Author(s):  
Bhavleen Kaur ◽  
Henrietta Mann
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Deep Sea ◽  
Bacterial Isolate ◽  
Wall Structure ◽  
Marine Agar ◽  
Gram Negative ◽  
Negative Cell ◽  
Transmission Electron ◽  
Microscopie Électronique

The ultrastructure of a bacterium, isolated from rusticles found on the wreck of the Royal Mail Steamship (R.M.S.) Titanic, was studied. The bacterium was rod-shaped, gram-negative and produced circular, off-white, opaque colonies on marine agar. Transmission electron microscopy revealed that the bacterium had a typical gram-negative cell wall structure; the nucleoid region was scattered throughout the cytoplasm and darkly stained inclusions were found in the cytoplasm. Negative staining illustrated the presence of 2-6 peritrichous flagella on the bacterium. This bacterial isolate may be part of transient consortia involved in the formation of the rusticles.On a étudié l’ultrastructure d’une bactérie, isolée de concrétions de rouille en stalactite provenant de l’épave du Royal Mail Steamship (R.M.S.) Titanic. La bactérie, en forme de bâtonnet, était Gram négatif et produisait des colonies circulaires, blanc cassé et opaques sur de l’agar marin. La microscopie électronique à transmission a révélé que la structure de la paroi cellulaire de la bactérie était typiquement Gram négatif; la région du nucléoïde était dispersée dans le cytoplasme, caractérisé par des inclusions foncées. La coloration négative a révélé la présence de 2 à 6 flagelles péritriches. Cet isolat bactérien pourrait faire partie des consortiums transitoires qui contribuent à la formation des concrétions de rouille.

scholarly journals Macroscopic and Microscopic Characteristics of 2- and 4-Year-Old Schizostachyum brachycladum

2019 ◽  
pp. 62-69
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Vascular Bundle ◽  
Middle Lamella ◽  
Cell Wall Structure ◽  
Wall Structure ◽  
Transmission Electron ◽  
Scanning Electron

Anatomical of cell wall structure on Schizostachyum brachycladum examined. The harvested two-year-old and four-year-old bamboo culms segregated into the bottom, middle and top portions. The samples then undergo the Light Microscopy (LM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) to determine their structure such as a vascular bundle, parenchyma, and sclerenchyma. Results show the surface of bamboo was visualized by LM to decide on their structural figure. In this part, 2-year age indicated that higher numbers of vascular bundle and average of mean compared to the 4-year S. brachycladum. Followed by a specific study of cell wall structure using SEM with highlighted 4-year S. brachycladum had more complex of morphology structure compared to the 2-year-old. Later on, TEM illustrated to shows most depth anatomically structure of bamboo such as middle lamella, primary and secondary walls.

scholarly journals Antileishmanial Activity of an Indole Alkaloid fromPeschiera australis

2001 ◽  
Vol 45 (5) ◽  
pp. 1349-1354 ◽  
Author(s):  
Jan Carlo Delorenzi ◽  
Márcia Attias ◽  
Cerli R. Gattass ◽  
Marcelo Andrade ◽  
Cláudia Rezende ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Analysis ◽  
New World ◽  
Indole Alkaloid ◽  
Antileishmanial Activity ◽  
Chemical Fractionation ◽  
Chloroform Fraction ◽  
Transmission Electron ◽  
Stem Extract

ABSTRACT In this study, we show the leishmanicidal effects of a chloroform fraction (CLF) and a purified indole alkaloid obtained from crude stem extract of Peschiera australis againstLeishmania amazonensis, a causative agent of cutaneous leishmaniasis in the New World. In a bioassay-guided chemical fractionation, the leishmanicidal activity in CLF completely and irreversibly inhibited promastigote growth. This fraction was also active against amastigotes in infected murine macrophages. Chemical analysis of CLF identified an iboga-type indole alkaloid coronaridine as one of its major compounds. Coronaridine showed potent antileishmanial activity, inhibiting promastigote and amastigote growth. Promastigotes and amastigotes treated with CLF or coronaridine showed pronounced alterations in their mitochondria as assessed by transmission electron microscopy.

Ultrastructure of the buccal capsule of the equine nematode Strongylus vulgaris with special reference to the dorsal gutter

1998 ◽  
Vol 72 (2) ◽  
pp. 167-177 ◽  
Author(s):  
M.S. Mobarak ◽  
M.F. Ryan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Special Reference ◽  
Preliminary Data ◽  
Buccal Capsule ◽  
Oesophageal Gland ◽  
Transmission Electron ◽  
Strongylus Vulgaris

AbstractEarly studies by light microscopy provided preliminary data on the fine structure of Strongylus vulgaris (Looss 1900). The present study employed transmission electron microscopy to investigate particular structures in the buccal capsule especially the dorsal gutter (DG) and teeth. The DG is a tube containing the terminal duct of the dorsal oesophageal gland (DOG) surrounded by two concentric canals. Putative pores indicated in the wall of the DG seen in other studies are revealed as honey-combed, fibrous, structures on each side of the ventral lamella. This lamella is formed by the wall of the DG internal canal running the length of the DG. Secretions of the DG canals are released through the dorsal gutter duct (DGD) which passes through the teeth bases at the base of the buccal capsule. Teeth have a vesicular cytoplasmic core containing various organelles.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

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