Effects of Killing by Heat or Desiccation on Membrane Structure in Pea Roots

1975 ◽  
Vol 2 (2) ◽  
pp. 225 ◽  
Author(s):  
MS Buttrose ◽  
JG Swift
Keyword(s):  
Membrane Structure ◽  
Structural Protein ◽  
Root Tips ◽  
Freeze Fracturing ◽  
Lipid Structure ◽  
Pea Seedlings ◽  
Thin Sectioning ◽  
Pea Seeds ◽  
Pea Roots ◽  
Dead Tissue

Radicles of dry pea seeds were killed by heating at temperatures up to 160°C, and root tips excised from pea seedlings were killed by desiccation. The effect of these treatments on the appearance of membranes was studied in the electron microscope after fixation and thin-sectioning and after freeze- fracturing, After fixation, membranes from dead tissue appeared modified in various ways compared with membranes from control tissue, whereas after freeze-fracturing they appeared unchanged. It is argued that heating and desiccation denature or disorganize structural protein in membranes but that they do not affect the lipid structure of the membrane.

An unusual cell surface modification: a double plasma membrane

1979 ◽  
Vol 39 (1) ◽  
pp. 355-372
Author(s):  
N.J. Lane ◽  
J.B. Harrison
Keyword(s):  
Plasma Membrane ◽  
Membrane Structure ◽  
Cell Layer ◽  
Peritrophic Membrane ◽  
Thin Sections ◽  
Double Membrane ◽  
Freeze Fracturing ◽  
Blood Sucking ◽  
Great Pressure ◽  
Insertion Sites

The occurrence of an unusual double plasma membrane structure is reported; it has been studied in conventional thin sections, after lanthanum-impregnation and with freeze-fracturing. This modification of the plasmalemma is found where the luminal cell membrane (I membrane) of gut microvilli in the haematophagous insect, Rhodnius prolixus, is surrounded by a second, outer membrane (O membrane), the 2 separated from one another by a highly regular I-O space of about 10 nm. Lanthanum impregnation reveals the presence of columns inclined at an angle, within this I-O space; as in the continuous junctions which link the lateral borders of these cells, these columns may maintain the very precise I-O distance. From the outer microvillar membranes radiate short spoke-like fibrils or sheets which encounter another more extensive system of myelin-like sheets. Freeze-fracturing reveals that the spoke-like sheets and the other ones which lie like a tube, around and parallel to the microvilli, contain linear ridges composed of particles, lying at random within layers of the myelin-like material which also extends into the lumen of the gut. The microvillar membanes, both O and I, fracture into faces containing rows of either PF particles or EF pits arranged as spiral ridges or grooves around the sides and across the tip of each microbillus. These could be the insertion sites of one or both of the I-O columns and spoke-like sheets while the sheets could represent a variant of peritrophic membrane. The double membrane may be a cellular device to increase the strength of the microvillar layer in these blood-sucking animals, since the cell layer must withstand great pressure owing to a sudden massive extension of the gut during a blood meal.

Excision and replication of extrachromosomal DNA of pea (Pisum sativum)

1983 ◽  
Vol 3 (2) ◽  
pp. 172-181
Author(s):  
J Van't Hof ◽  
C A Bjerknes ◽  
N C Delihas
Keyword(s):  
Cell Cycle ◽  
Pisum Sativum ◽  
S Phase ◽  
Velocity Sedimentation ◽  
Extrachromosomal Dna ◽  
Chromosomal Dna ◽  
Root Tips ◽  
Dividing Cells ◽  
G2 Phase ◽  
Pea Roots

Experiments with cultured pea roots were conducted to determine (i) whether extrachromosomal DNA was produced by cells in the late S phase or in the G2 phase of the cell cycle, (ii) whether the maturation of nascent DNA replicated by these cells achieved chromosomal size, (iii) when extrachromosomal DNA was removed from the chromosomal duplex, and (iv) the replication of nascent chains by the extrachromosomal DNA after its release from the chromosomal duplex. Autoradiography and cytophotometry of cells of carbohydrate-starved root tips revealed that extrachromosomal DNA was produced by a small fraction of cells accumulated in the late S phase after they had replicated about 80% of their DNA. Velocity sedimentation of nascent chromosomal DNA in alkaline sucrose gradients indicated that the DNA of cells in the late S phase failed to achieve chromosomal size. After reaching sizes of 70 X 10(6) to 140 X 10(6) daltons, some of the nascent chromosomal molecules were broken, presumably releasing extrachromosomal DNA several hours later. Sedimentation of selectively extracted extrachromosomal DNA either from dividing cells or from those in the late S phase showed that it replicated two nascent chains, one of 3 X 10(6) daltons and another of 7 X 10(6) daltons. Larger molecules of extrachromosomal DNA were detectable after cells were labeled for 24 h. These two observations were compatible with the idea that the extrachromosomal DNA was first replicated as an integral part of the chromosomal duplex, was cut from the duplex, and then, once free of the chromosome, replicated two smaller chains of 3 X 10(6) and 7 X 10(6) daltons.

A technique for freeze fracturing minute amounts of isolated cardiac membrane

1981 ◽  
Vol 241 (6) ◽  
pp. H891-H893
Author(s):  
Y. Shibata ◽  
C. K. Manjunath
Keyword(s):  
Membrane Structure ◽  
Freeze Fracture ◽  
Multiple Fractures ◽  
Freeze Fracturing ◽  
Internal Membrane ◽  
Unequivocal Identification ◽  
Biochemical Studies ◽  
Membrane Type ◽  
Dialysis Bag ◽  
Internal Membrane Structure

Electron microscopy (EM) of freeze-fractured membranes provides more information about internal membrane structure than EM of thin-sectioned or negatively stained material. However, it has heretofore been impractical to use freeze fracture routinely for analysis of highly purified membrane fractions obtainable in small (micrograms) amounts, because the technique, when conventionally applied to minute pellets, yields only one fracture of unpredictable quality; it also precludes in parallel biochemical studies by using up the entire preparation. To solve this problem, we have developed a method for freeze fracturing tiny droplets of suspended membranes containing 1-10 micrograms membrane protein, thereby allowing both multiple fractures and biochemical studies. Before fracture, the final membrane fractions can be concentrated, subjected to experimental manipulations, cross-linked, and glycerinated in a dialysis bag. The technique is illustrated on isolated gap junctions from rabbit hearts, which were chosen because their unique internal membrane structure allows unequivocal identification of membrane type based on structural criteria.

Einfluß von Tetraphenylborat auf die Feinstruktur von Zellen der Maiswurzelspitze / Influence of Tetraphenylboron on Fine Structure of Cells of Corn Root Tips

1970 ◽  
Vol 25 (12) ◽  
pp. 1477-1479 ◽  
Author(s):  
Charlotte Hecht-Buchholz ◽  
Horst Marschner
Keyword(s):  
Fine Structure ◽  
Membrane Structure ◽  
Endoplasmatic Reticulum ◽  
Root Tips ◽  
Root Cortex ◽  
Double Membrane ◽  
Corn Root ◽  
Ca 50 ◽  
Root Cortex Cells

Treatment (1-3h) of corn root tips with 5 × 10-5ᴍ tetraphenylboron (TPB) caused characteristic changes of the membrane structure in the outer layers of the root cortex cells. The mitochondria had lost their inner structure. At the double membrane of the mitochondria and at the membrane plasmalemma, tonoplast, and endoplasmatic reticulum there appeared numerous osmiophilic globuli (ca. 50 nm). The permeability of the membranes seemed to be increased extremely. It is suggested that the lipoproteine complex of the membranes was destroyed by interaction of TPB with ammonium groups of the membrane constituents

The Effect of Germination on Antioxidant and Nutritional Parameters of Protein Isolates from Grass Pea (Lathyrus sativus) Seeds

2010 ◽  
Vol 16 (1) ◽  
pp. 73-77 ◽  
Author(s):  
A. Starzyńska-Janiszewska ◽  
B. Stodolak ◽  
B. Mickowska
Keyword(s):  
Antioxidant Properties ◽  
Sulfur Amino Acids ◽  
Grass Pea ◽  
Protein Isolates ◽  
Nutritional Parameters ◽  
Pea Seedlings ◽  
Total Antioxidant ◽  
Pea Seeds ◽  
Potential Food

The aim of this research was to study the antioxidant and nutritional (selected objects) properties of protein isolates obtained from grass pea seedlings as compared with soaked and raw seeds. Two percent extract of isolate from 5-day-old seedlings showed the highest total antioxidant activity (25%) and the ability to chelate Fe 2+ (2.35 mg/g d.m.) as compared with other isolates. Protein isolates from grass pea seeds had on average 89% total protein, 87% in vitro protein bioavailability, about 5574 TIU/g (d.m.) (trypsin inhibitors activity) and did not contain ODAP. Germination of seeds for 5 days considerably improved the in vitro bioavailability of isolates, by 12%, and profile of sulfur amino acids by 42%, in comparison with isolates obtained from the raw seeds. Isolates from 5-day-old grass pea seedlings had the best antioxidant properties and improved nutritional parameters (as compared with raw seeds), which makes them worthy of being considered as a potential food additive.

Métabolisme intracellulaire et extracellulaire de l'acide 3-indolylacétique dans les cultures aseptiques ou non aseptiques de pointes de racine du Pisum sativum

1968 ◽  
Vol 46 (8) ◽  
pp. 969-978 ◽  
Author(s):  
G. F. Collet
Keyword(s):  
Absorption Spectrum ◽  
Pisum Sativum ◽  
Indoleacetic Acid ◽  
Specific Activity ◽  
High Specific Activity ◽  
Ultraviolet Absorption Spectrum ◽  
Root Tips ◽  
Pea Seedlings ◽  
Oxidase Inhibition ◽  
Layer Chromatography

Studies on indoleacetic acid (IAA) metabolism with root tips of 3-day-old pea seedlings were carried out by thin-layer chromatography and 14C-labelled auxin of high specific activity at 10−6 M. After 16-h incubation, five metabolites of IAA could be recognized in the tissues and two in solution; one metabolite was identified as o-formamidoacetophenone from its chromatographic Rf and ultraviolet absorption spectrum. Under sterile conditions the rate of breakdown of IAA is higher in the medium than under nonsterile conditions (even after removal of the tissues). We noted, too, a decrease of the action of IAA on the growth. The decreased activity of solution under nonsterile conditions is believed to be due to the production of oxidase inhibition by microorganisms.

scholarly journals Ultrastructure of the sodium pump: Comparison of thin sectioning, negative staining, and freeze-fracture of purified, membrane-bound (Na+, K+)-ATPase

1977 ◽  
Vol 75 (3) ◽  
pp. 619-634 ◽  
Author(s):  
N Deguchi ◽  
PL Jorgensen ◽  
AB Maunsbach
Keyword(s):  
Membrane Surface ◽  
Freeze Fracture ◽  
Negative Staining ◽  
Intramembranous Particle ◽  
Freeze Fracturing ◽  
Intramembranous Particles ◽  
Membrane Surfaces ◽  
Thin Sectioning ◽  
Surface Particle ◽  
Protein Components

Purified (Na+, K+)-ATPase was studied by electron microscopy after thin sectioning, negative staining, and freeze-fracturing, particular emphasis being paid to the dimensions and frequencies of substructures in the membranes. Ultrathin sections show exclusively flat or cup-shaped membrane fragments which are triple-layered along much of their length and have diameters of 0.1-0.6 μm. Negative staining revealed a distinct substructure of particles with diameters between 30 and 50 A and with a frequency of 12,500 +/- 2,400 (SD) per μm(2). Comparisons with sizes of the protein components suggest that each surface particle contains as its major component one large catalytic chain with mol wt close to 100,000 and that two surface particles unite to form the unit of (Na+,K+)-ATPase which binds one molecule of ATP or ouabain. The further observations that the surface particles protrude from the membrane surface and are observed on both membrane surfaces in different patterns and degrees of clustering suggest that protein units span the membrane and are capable of lateral mobility. Freeze-fracturing shows intramembranous particles with diameters of 90-110 A and distributed on both concave and convex fracture faces with a frequency of 3,410 +/- 370 per μm(2) and 390 +/- 170 per μm(2), respectively. The larger diameters and three to fourfold smaller frequency of the intramembranous particles as compared to the surface particles seen after negative staining may reflect technical differences between methods, but it is more likely that the intramembranous particle is an oliogomer composed of two or even more of the protein units which form the surface particles.

Membrane structure as seen with a double replica method for freeze fracturing

1970 ◽  
Vol 59 (2) ◽  
pp. 336-339 ◽  
Author(s):  
E. Wehrli ◽  
K. Mühlethaler ◽  
H. Moor
Keyword(s):  
Membrane Structure ◽  
Replica Method ◽  
Freeze Fracturing

Teliospores of Entorrhiza casparyana (Ustilaginales): a correlated thin-sectioning and freeze–fracture study of endogenously dormant spores

1984 ◽  
Vol 62 (12) ◽  
pp. 2525-2539 ◽  
Author(s):  
Brian A. Fineran ◽  
Judith M. Fineran
Keyword(s):  
Outer Layer ◽  
Freeze Fracture ◽  
Middle Layer ◽  
Wall Material ◽  
Lipid Bodies ◽  
Freeze Fracturing ◽  
Thin Sectioning ◽  
Single Nucleus ◽  
Fracture Study ◽  
Small Clusters

A correlated thin-sectioning and freeze–fracturing approach was used to reveal the ultrastructure of endogenously dormant teliospores in the smut fungus Entorrhiza casparyana (Magn.) Lagerh. Conventional fixation and embedding methods yielded poor preservation of the wall and protoplasm. Successful preservation was achieved by fixing frozen and cryosectioned spores in glutaraldehyde and subsequently processing by standard procedures for transmission electron microscopy. Freeze–fracturing provided cross- and contour-fractured views of the protoplasm and the different layers of the wall. The wall is thick, consisting of three main layers: outer, middle, and inner, with the outer and inner layers further differentiated into zones. The warty zone dominates the outer layer and consists of radial protuberances (warts) with the regions between filled to varying degrees with similar wall material containing electron-transparent lamellae. The extent of differentiation of the warty zone is reflected in the surface morphology of the spores, which ranges from verrucose to almost smooth. At the base of the outer layer is an electron-translucent irregular zone. The middle and inner layers are regular in thickness around the spore, with the middle layer being the most electron dense. The inner layer is differentiated into three zones. The most distinctive is zone 2 which in freeze–fractured walls has an unique mosaic of striae. Cytochemical staining of the wall for polysaccharide material gives a positive reaction only for the warty zone. The protoplasm contains a single nucleus and is dominated by numerous spheroidal storage lipid bodies. Squeezed among the lipid bodies are organelles, believed to be microbodies, containing a granular matrix and often electron-transparent areas. These organelles failed to show catalase activity with the 3,3′-diaminobenzidine method. Occasional short profiles of endoplasmic reticulum cisternae, a few mitochondria with sparse cristae, dispersed small clusters of glycogen, and sometimes scattered ribosomes are also present in the cytoplasm. All these features are typical of dormant spores with a low metabolic activity.

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