Phytochrome-induced structural changes and protein degradation prior to radicle protrusion in Datura ferox seeds

1995 ◽  
Vol 73 (9) ◽  
pp. 1371-1378 ◽  
Author(s):  
R. A. Mella ◽  
R. A. Sànchez ◽  
S. Maldonado
Keyword(s):  
Protein Degradation ◽  
Protein Content ◽  
Structural Changes ◽  
Red Light ◽  
Light And Electron Microscopy ◽  
Protein Bodies ◽  
Embryonic Axes ◽  
Radicle Protrusion ◽  
Micropylar Endosperm ◽  
Extensive Degradation

In Datura ferox L. seeds induced to germinate by the far-red light absorbing form of phytochrome (Pfr) and alternating temperatures, protein degradation started before radicle protrusion. Proteolysis was, however, restricted to the micropylar region of the endosperm in which the protein content decreased 51% by 48 h after red light treatment. There was no change during that time in the protein content of the rest of the endosperm or in the embryo. Light and electron microscopy preparations show the vacuolation of protein bodies along with other changes in cellular structure in the micropylar portion of the endosperm in seeds treated with red light (R). No changes were detected in the rest of the endosperm or in the micropylar portions of far-red light (FR) treated seeds. In the embryonic axes there were some alterations but only in a small sector of the calyptra. In contrast, shortly after radicle protrusion (5 h), there was extensive degradation of protein bodies in the embryonic axes. A Pfr is required for the induction of protein degradation in the micropylar portion of the endosperm in the intact seed before radicle protrusion. Incubation of isolated micropylar portions induced protein degradation in tissues from seeds treated with either R or FR. The results do not support a source–sink type of control of protein degradation in the endosperm driven by the beginning of embryo growth but suggest the participation of regulatory signals in the determination of a temporal and spatial pattern of protein degradation in both the endosperm and the embryo. Key words: germination, dormancy, phytochrome, protein degradation, micropylar endosperm.

Structural Aspects of Protein Accumulation in Developing Pea Cotyledons. I. Qualitative and Quantitative Changes in Parenchyma Cell Vacuoles

1979 ◽  
Vol 6 (1) ◽  
pp. 81 ◽  
Author(s):  
S Craig ◽  
DJ Goodchild ◽  
AR Hardham
Keyword(s):  
Cell Volume ◽  
Surface Area ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Parenchyma Cell ◽  
Protein Body ◽  
Average Diameter ◽  
Protein Bodies ◽  
Protein Accumulation ◽  
Parenchyma Cells

Structural changes in pea cotyledons during development were studied using light and electron microscopy. Changes in the vacuolar system and cytoplasm of cotyledon parenchyma cells, during the period of storage protein deposition, are reported. Eight days after flowering, the parenchyma cells each contain one or two large vacuoles that are replaced by progressively smaller vacuoles during the next 10 days of development. Stainable material that can be histochemically identified as protein appears on the inner surface of the vacuole tonoplast 8 days after flowering. These vacuoles become smaller and more frequent during development and the amount of proteinaceous material within each vacuole increases until, at days 16-20 after flowering, they become densely packed with protein and are described as protein bodies. At day 8, the vacuole(s) have an average diameter of 39 �m, an average volume of 41 000 �m� , representing 75 % of the cell volume, and a surface area of 5500 �m�. By day 20, the average protein body diameter has fallen to 1 �m. There are, however, approx. 175 000 such protein bodies per cell, occupying 91 500 �m� or approx. 20 % of the cell volume, and whose total surface area is 550 000 �m�. The surface to volume ratlo of the vacuole/protein bodies Increases 55 times between days 8 and 20. Apart from this increase in surface area available for possible entry of protein, no mechanism for such entry can be suggested from our nlicrographs.

An Ultrastructural and Radio-Autographic Study of the Evolution of the Interphase Nucleus in Plant Meristematic Cells (Allium Porrum)

1974 ◽  
Vol 14 (2) ◽  
pp. 263-287
Author(s):  
J. G. LAFONTAINE ◽  
A. LORD
Keyword(s):  
Interphase Nucleus ◽  
Structural Changes ◽  
Tritiated Thymidine ◽  
Light And Electron Microscopy ◽  
Allium Porrum ◽  
Meristematic Cells ◽  
Fibrillar Material ◽  
Nuclear Structures ◽  
S Period ◽  
Dense Chromatin

Radioautography under both light and electron microscopy was exploited to investigate the structural changes of the chromatin reticulum which characterizes the interphase nucleus of a number of plants. Allium porrum meristematic plant cells were used for this purpose. In this species, the telophase chromosomes uncoil into dense strands which, during the G1 period, gradually give rise to a coarse reticulum. There then follows an extensive unravelling of portions of these strands, and high-resolution radioautography reveals that labelling with tritiated thymidine predominantly occurs over zones of the nucleus consisting of diffuse fine fibrillar material. As the S-period progresses, a chromatin reticulum reappears throughout the nuclear cavity, the tortuous strands being approximately 0.25 µm in diameter. Most of the radioautographic grains still remain over the light nucleoplasmic areas but a number of these are now located on the outermost portion of the dense chromatin profiles. By the end of the S-period, the chromatin strands are slightly thicker (ca. 0.3 µm) and form a looser reticulum. Labelling has decreased noticeably in nuclei of that period, the radioautographic grains being grouped into clusters resting over more or less spherical regions of the chromatin reticulum. Judging from their localization at the surface of the nucleolus or close to the nuclear envelope, these structures correspond to chromocentres. The additional interesting finding that such nuclear structures appear much less compactly organized strongly suggests that chromocentres undergo important conformational modifications during duplication of their DNA.

Cerebral autosomo-dominant arteriopathy with subcortical infarctions and leukoencephalopathy

2021 ◽  
Vol 26 (5) ◽  
pp. 30-38
Author(s):  
E. A. Savchuk ◽  
E. P. Golubinskaya ◽  
T. N. Shcherbinina ◽  
G. Yu. Voronin ◽  
E. O. Savchuk ◽  
...  
Keyword(s):  
Clinical Case ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Joint Work ◽  
Genetic Studies ◽  
Small Vessels ◽  
Clinical Case Study ◽  
The Family ◽  
Probable Diagnosis

The article presents an analysis of the literature and a clinical case of a rare disease from the group of diseases of small vessels — cerebral autosomal dominant arteriopathy with subcortical infarction and leukoencephalopathy (CADASIL).It is based on the deposition of osmiophilic granulation material in vessels of small and medium caliber. A mutation in the NOTCH3 gene on chromosome 19p13 leads to significant structural changes in the walls of small arteries due to impaired differentiation and maturation of smooth muscle cells.CADASIL is characterized by four key symptoms: migraines, recurrent ischemic strokes, mental disorders, and cognitive decline. The clinical case study is presented from the standpoint of a multidisciplinary patient-oriented approach of joint work of neurologists and morphologists. On the basis of clinical and laboratory criteria, a probable diagnosis was made. To confirm it, a muscle biopsy was performed (a musculocutaneous flap from the inner surface of the thighs and forearms), in order to conduct light and electron microscopy. The details of the results of the morphological study, which made it possible to verify the patient’s diagnosis, are presented. Differential diagnostic judgments are presented and recommendations for genetic studies in the family, prognosis and treatment of the patient are given.

Functional medial thickening and folding of the internal elastic lamina in coronary spasm

2011 ◽  
Vol 300 (2) ◽  
pp. H423-H430 ◽  
Author(s):  
Yasumi Uchida ◽  
Yasuto Uchida ◽  
Akimasa Matsuyama ◽  
Atsushi Koga ◽  
Yuko Maezawa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Coronary Spasm ◽  
Cellular Level ◽  
Internal Elastic Lamina ◽  
Circular Smooth Muscle ◽  
The Media ◽  
Medial Thickening ◽  
Elastic Lamina

Although there are a number of studies on vasospastic angina, the structural changes at the cellular level that occur in the coronary arterial wall during spasm are not well known. Coronary spasm was induced by brushing the coronary adventitia in nine anesthetized beagles, and structural changes in the spastic coronary segments were examined by light and electron microscopy, making comparisons with the adjacent nonspastic segments. The % diameter stenosis of the spastic segments as measured angiographically was 79.4 ± 12% (mean ± SD). Light microscopic changes in the spastic and nonspastic segments were as follows: medial thickness 1,512 vs. 392 μm ( P < 0.0001) and % diameter and % area stenoses of spastic segment 81.0% and 96.5%, respectively, indicating that spasm was induced by medial thickening. Circular smooth muscle cells (SMCs) in the media were arranged in parallel with the internal (IEL) and external (EEL) elastic lamina in nonspastic segments but radially rearranged in spastic segments. SMCs were classified by their patterns of connection to IEL into six types by electron microscopy. Of these, three contracted and pulled the IEL toward the EEL, causing folding of the IEL and waving of EEL resulting in thickening of the media and narrowing of the lumen. We conclude that coronary spasm was elicited by radial rearrangement of the medial SMCs due to their own contraction and resultant medial thickening and folding of IEL, creating a piston effect to narrow the lumen, i.e., spasm.

Ultrastructure of Protein Bodies in Embryonic Axes of Soybean Seeds (Glycine maxcv. Enrei)

1990 ◽  
Vol 54 (7) ◽  
pp. 1847-1848
Author(s):  
Michiko Monma ◽  
Toshio Sugimoto ◽  
Kazumoto Hashizume ◽  
Kyoko Saio
Keyword(s):  
Protein Bodies ◽  
Soybean Seeds ◽  
Embryonic Axes

scholarly journals Thermal Stress, Aggregation of Chlorophyll-Protein Complexes, and Light-Dependent Recovery of PSII activity in Wheat Seedlings

2021 ◽  
Vol 68 (5) ◽  
pp. 867-872
Author(s):  
M. S. Khristin ◽  
T. N. Smolova ◽  
V. D. Kreslavski
Keyword(s):  
Low Temperature ◽  
Structural Changes ◽  
Protein Complexes ◽  
Red Light ◽  
Photochemical Activity ◽  
Wheat Seedlings ◽  
Psii Activity ◽  
Temperature Spectra ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

Abstract The dynamics of changes in the photochemical activity of photosystem II (PSII) and low-temperature spectra at 77 K in the first leaves of 11-day winter wheat plants Triticum aestivum L., as well as structural changes in chlorophyll-protein complexes (CPC) of thylakoid membranes during recovery after a short-term (20 min) heating at a temperature of 42°C, were studied. Changes in the Fv/Fm, F735/F695, and F735/F685 ratios indicate inhibition of PSII immediately after heating. Using nondenaturing electrophoresis, it was shown that the light-harvesting Chl a/b complex of PSII does not aggregate immediately after heating but after several hours, after 6 h the desagregation of CPC was observed, which was consistent with an increase in the Fv/Fm ratio upon recovery. The influence of temperature, intensity, and quality of light (white, blue, and red light) on the recovery of PSII activity and low-temperature fluorescence spectra was studied. It was concluded that the recovery is a photo-activated low-energy process, independent of photosynthesis, and the most effective in blue light.

scholarly journals The primary structural photoresponse of phytochrome proteins captured by a femtosecond X-ray laser

2019 ◽  
Author(s):  
Elin Claesson ◽  
Weixiao Yuan Wahlgren ◽  
Heikki Takala ◽  
Suraj Pandey ◽  
Leticia Castillon ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Structural Changes ◽  
Red Light ◽  
Crystallographic Data ◽  
Water Dissociation ◽  
X Ray ◽  
Binding Domains ◽  
Delay Times

Phytochrome proteins control the growth, reproduction, and photosynthesis of plants, fungi, and bacteria. Light is detected by a bilin cofactor, but it remains elusive how this leads to activation of the protein through structural changes. We present serial femtosecond X-ray crystallographic data of the chromophore-binding domains of a bacterial phytochrome at delay times of 1 ps and 10 ps after photoexcitation. The structures reveal a twist of the D-ring, which lead to partial detachment of the chromophore from the protein. Unexpectedly, the conserved so-called pyrrole water is photodissociated from the chromophore, concomitant with movement of the A-ring and a key signalling aspartate. The changes are wired together by ultrafast backbone and water movements around the chromophore, channeling them into signal transduction towards the output domains. We suggest that the water dissociation is key to the phytochrome photoresponse, explaining the earliest steps of how plants, fungi and bacteria sense red light.

Hydra regeneration from recombined ectodermal and endodermal tissue. II. Differential stability in the ectodermal and endodermal epithelial organization

1997 ◽  
Vol 110 (16) ◽  
pp. 1919-1934
Author(s):  
M. Murate ◽  
Y. Kishimoto ◽  
T. Sugiyama ◽  
T. Fujisawa ◽  
H. Takahashi-Iwanaga ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Single Layer ◽  
Strong Interactions ◽  
High Plasticity ◽  
Spherical Structure ◽  
Epithelial Sheet ◽  
Differential Stability ◽  
Tissue Recombination

Hydra tissue consists of the ectodermal and the endodermal layers. When the two layers were separated by procaine treatment and then recombined, the ectodermal epithelial cells spread as a single cell layer over the endoderm as in epiboly in vertebrate embryogenesis, and the resultant spherical structure subsequently regenerated into a complete hydra. In this study, light and electron microscopy were used to examine the structural changes which took place in the cells and tissue during this epibolic ectodermal spreading process. Within a few hours after tissue recombination, the endoderm underwent dramatic changes; it lost its epithelial sheet organization, and turned into a mass of irregularly shaped cells without the apical-basal cell polarity initially present. In contrast, the ectoderm maintained its basic epithelial sheet organization as it spread over the endoderm. Later, the endodermal epithelial cells reorganized themselves into a single-layered epithelial sheet underneath the spreading ectodermal layer. The resultant spherical structure consisted of a single layer of ectodermal epithelial cells outside, a single layer of endodermal epithelial cells inside, and an empty cavity in the center as in normal hydra tissue. This structure regenerated into hydra in the following days. These and other observations demonstrate that the two-layered epithelial sheet organization is highly dynamic, and that its stability is maintained by strong interactions between the two layers in normal hydra. It is suggested that this dynamic nature of the hydra tissue, particularly the high plasticity of the endodermal epithelial sheet organization, may be an important element for the high regenerative capacity of this organism.

scholarly journals Trypanosoma congolense in the Microvasculature of the Pituitary Gland of Experimentally Infected Boran Cattle (Bos indicus)

1993 ◽  
Vol 30 (5) ◽  
pp. 401-409 ◽  
Author(s):  
G. Abebe ◽  
M. K. Shaw ◽  
R. M. Eley
Keyword(s):  
Electron Microscopy ◽  
Extracellular Matrix ◽  
Structural Changes ◽  
Bos Indicus ◽  
Light And Electron Microscopy ◽  
Trypanosoma Congolense ◽  
Glossina Morsitans ◽  
Glossina Morsitans Centralis ◽  
Pituitary Glands ◽  
Female Control

The pituitary glands of seven Boran cattle ( Bos indicus), five infected with a clone of Trypanosoma congolense IL 1180 (ILNat 3.1) transmitted by Glossina morsitans centralis and two uninfected controls, were examined by light and electron microscopy 43 (experiment 2) or 56 (experiment 1) days after fly challenge. The three cattle used in the first experiment included a 15-month-old female (No. 1), a 24–month-old female (No. 2), and a 21–month-old male (No. 3) as a control. In the second experiment, four cattle were used: two females (Nos. 4, 5) and one male (No. 6), all between 15 and 24 months of age, and one female control (No. 7) of similar age. In all the infected animals, dilation of both the sinusoids and microvasculature was apparent, as was an increase in the thickness of the extracellular matrix between the pituitary lobules. Trypanosomes were found in the microvasculature of the adenohypophysis and neurohypophysis in all the infected animals. Focal degenerative changes were seen in the adenohypophyseal section of glands from the infected animals euthanatized 56 days post-infection. These degenerative structural changes were confined to the somatotrophs cells. The possible role that trypanosomes in the microvasculature may play in inducing pituitary damage and dysfunction is discussed.

scholarly journals Protein degradation rate as affected by plant proteases among fresh samples of perennial ryegrass cultivars (Lolium perenne L.) / Einfluss pflanzlicher Proteasen auf den Proteinabbau bei unterschiedlichen Englischen Raigrass Sorten (Lolium perenne L.)

2016 ◽  
Vol 67 (2) ◽  
pp. 61-68
Author(s):  
Martin Gierus ◽  
Marc Loesche ◽  
Heba Salama ◽  
Antje Herrmann ◽  
Friedhelm Taube
Keyword(s):  
Protein Degradation ◽  
Protein Content ◽  
Lolium Perenne ◽  
Perennial Ryegrass ◽  
Incubation Time ◽  
Large Subunit ◽  
Ethanol Solution ◽  
Bisphosphate Carboxylase ◽  
Lolium Perenne L ◽  
Degradation Rates

Summary The objective of this study was to quantify the proteolytic activity of a set of 10 diploid early intermediate heading cultivars of Lolium perenne under rumenlike conditions. A field experiment was conducted in Northern Germany, where the perennial ryegrass cultivars were grown during two growing seasons. Leaves of the first and second cut were sampled in the field, sterilized with 800 ml. l−1 ethanol solution and incubated for 0, 6, and 24 h under rumenlike conditions (darkness, 39°C, pH 6.5) without the presence of rumen microbes. Results revealed that the leaf protein content declined with increasing incubation time, confirming the involvement of plant-mediated proteolysis in the degradation process. Gel electrophoresis illustrated that the decrease in protein content is probably mainly caused by the loss of the large subunit of Rubisco (ribulose-1, 5-bisphosphate carboxylase/oxygenase), which was entirely degraded during the incubation time. Although differences among harvests and years were evident, genetic variation among the 10 diploid perennial grass samples concerning protein degradation rates and degradation characteristics was not detected.

Sign in / Sign up

Export Citation Format

Share Document