scholarly journals Dark-Induced Barley Leaf Senescence – A Crop System for Studying Senescence and Autophagy Mechanisms

2021 ◽  
Vol 12 ◽  
Author(s):  
Ewelina Paluch-Lubawa ◽  
Ewelina Stolarska ◽  
Ewa Sobieszczuk-Nowicka
Keyword(s):  
Leaf Senescence ◽  
Control Mechanism ◽  
Morphological Changes ◽  
Plant Cells ◽  
Cell Components ◽  
Barley Leaf ◽  
Quality Control Mechanism ◽  
Crop System ◽  
Made In

This review synthesizes knowledge on dark-induced barley, attached, leaf senescence (DILS) as a model and discusses the possibility of using this crop system for studying senescence and autophagy mechanisms. It addresses the recent progress made in our understanding of DILS. The following aspects are discussed: the importance of chloroplasts as early targets of DILS, the role of Rubisco as the largest repository of recoverable nitrogen in leaves senescing in darkness, morphological changes of these leaves other than those described for chloroplasts and metabolic modifications associated with them, DILS versus developmental leaf senescence transcriptomic differences, and finally the observation that in DILS autophagy participates in the circulation of cell components and acts as a quality control mechanism during senescence. Despite the progression of macroautophagy, the symptoms of degradation can be reversed. In the review, the question also arises how plant cells regulate stress-induced senescence via autophagy and how the function of autophagy switches between cell survival and cell death.

Vacuolar convolution: possible mechanisms and role of phosphatidylinositol 3,5-bisphosphate

2017 ◽  
Vol 44 (8) ◽  
pp. 751 ◽  
Author(s):  
Vadim Pérez Koldenkova ◽  
Noriyuki Hatsugai
Keyword(s):  
Morphological Changes ◽  
Stomatal Closure ◽  
Plant Cells ◽  
Reversible Transformation ◽  
Large Central Vacuole ◽  
Cellular Integrity ◽  
Lytic Vacuole ◽  
Cellular Cytoskeleton

The central or lytic vacuole is the largest intracellular organelle in plant cells, but we know unacceptably little about the mechanisms regulating its function in vivo. The underlying reasons are related to difficulties in accessing this organelle without disrupting the cellular integrity and to the dynamic morphology of the vacuole, which lacks a defined structure. Among such morphological changes, vacuolar convolution is probably the most commonly observed event, reflected in the (reversible) transformation of a large central vacuole into a structure consisting of interconnected bubbles of a smaller size. Such behaviour is observed in plant cells subjected to hyperosmotic stress but also takes place in physiological conditions (e.g. during stomatal closure). Although vacuolar convolution is a relatively common phenomenon in plants, studies aimed at elucidating its execution mechanisms are rather scarce. In the present review, we analyse the available evidence on the participation of the cellular cytoskeleton and ion transporters in vacuolar morphology dynamics, putting special emphasis on the available evidence of the role played by phosphatidylinositol 3,5-bisphosphate in this process.

scholarly journals The role of cytokinins in the development and metabolism of barley leaves. I. The effect of cytokinins on leaf senescence

2015 ◽  
Vol 46 (2) ◽  
pp. 357-368 ◽  
Author(s):  
A. Woźny ◽  
A. Szweykowska ◽  
J. Legocka
Keyword(s):  
Nucleic Acids ◽  
Leaf Senescence ◽  
Rna Synthesis ◽  
Similar Extent ◽  
Mesophyll Cells ◽  
Barley Leaves ◽  
Barley Leaf ◽  
Cytokinin Action ◽  
Natural Cytokinin

The loss of chlorophyll during dark-induced ageing of barley leaves was prevented to a similar extent by kinetin and the natural cytokinin, 6-Δ<sup>2</sup>-iso-pentenylarninopurine (2iP). A concentration of 400 μM appeared to be optimal in both cases. In the presence of 2iP the structure of mesophyll cells in dark-incubated leaves was maintained unchanged. A distinct correlation has been found between the retardation by 2iP of the chlorophyll loss, the rate of S2P-incorporation into nucleic acids and the maintaining of the RNase activity at a low level. The importance of the RNA synthesis and the rate of its de-gradation in the cytokinin action in barley leaf senescence will be subjected to future experiments.

scholarly journals Optineurin mediates delivery of membrane from transferrin receptor-positive endosomes to autophagosomes

2022 ◽  
Author(s):  
Megha Bansal ◽  
Kapil Sirohi ◽  
Shivranjani C Moharir ◽  
Ghanshyam Swarup
Keyword(s):  
Transferrin Receptor ◽  
Control Mechanism ◽  
Adaptor Protein ◽  
Wild Type ◽  
Autophagosome Formation ◽  
Embryonic Fibroblasts ◽  
Over Expression ◽  
Ubiquitin Binding ◽  
Quality Control Mechanism

Autophagy is a conserved quality control mechanism that removes damaged proteins, organelles and invading bacteria through lysosome-mediated degradation. During autophagy several organelles including endoplasmic reticulum, mitochondria, plasma membrane and endosomes contribute membrane for autophagosome formation. However, the mechanisms and proteins involved in membrane delivery to autophagosomes are not clear. Optineurin (OPTN), a cytoplasmic adaptor protein, is involved in promoting maturation of phagophores into autophagosomes; it is also involved in regulating endocytic trafficking and recycling of transferrin receptor (TFRC). Here, we have examined the role of optineurin in the delivery of membrane from TFRC-positive endosomes to autophagosomes. Only a small fraction of autophagosomes was positive for TFRC, indicating that TFRC-positive endosomes could contribute membrane to a subset of autophagosomes. The percentage of TFRC-positive autophagosomes was reduced in Optineurin knockout mouse embryonic fibroblasts (Optn-/-MEFs) in comparison with normal MEFs. Upon over-expression of optineurin, the percentage of TFRC-positive autophagosomes was increased in Optn-/- MEFs. Unlike wild-type optineurin, a disease-associated mutant, E478G, defective in ubiquitin binding, was not able to enhance formation of TFRC-positive autophagosomes in Optn-/- MEFs. TFRC degradation mediated by autophagy was decreased in optineurin deficient cells. Our results suggest that optineurin mediates delivery of TFRC and perhaps associated membrane from TFRC-positive endosomes to autophagosomes, and this may contribute to autophagosome formation.

scholarly journals Role of skeletal muscle autophagy in high-fat-diet–induced obesity and exercise

2019 ◽  
Vol 78 (1) ◽  
pp. 56-64
Author(s):  
Adrienne R Herrenbruck ◽  
Lance M Bollinger
Keyword(s):  
Skeletal Muscle ◽  
High Fat Diet ◽  
Control Mechanism ◽  
Degradation Pathway ◽  
The Body ◽  
High Fat ◽  
Diet Induced Obesity ◽  
Quality Control Mechanism ◽  
The Impact

Abstract Autophagy is a complex degradation pathway responsible for clearing damaged and dysfunctional organelles. High-fat-diet–induced obesity has been shown to alter autophagy throughout the body in a tissue-specific manner. The impact of obesity on skeletal muscle autophagy has yet to be elucidated. This review examines the impact of high-fat-diet–induced obesity and exercise on skeletal muscle autophagy. Better understanding this major quality control mechanism may help develop novel therapies to combat high-fat-diet–induced obesity comorbidities.

scholarly journals Molecular Control of Carpel Development in the Grass Family

2021 ◽  
Vol 12 ◽  
Author(s):  
Chaoqun Shen ◽  
Gang Li ◽  
Ludovico Dreni ◽  
Dabing Zhang
Keyword(s):  
Morphological Changes ◽  
Reproductive Organ ◽  
Molecular Control ◽  
Grass Family ◽  
Female Reproductive Organ ◽  
Carpel Development ◽  
Molecular Aspects ◽  
Vital Element ◽  
Made In

Carpel is the ovule-bearing female reproductive organ of flowering plants and is required to ensure its protection, an efficient fertilization, and the development of diversified types of fruits, thereby it is a vital element of most food crops. The origin and morphological changes of the carpel are key to the evolution and adaption of angiosperms. Progresses have been made in elucidating the developmental mechanisms of carpel establishment in the model eudicot plant Arabidopsis thaliana, while little and fragmentary information is known in grasses, a family that includes many important crops such as rice (Oryza sativa), maize (Zea mays), barley (Hordeum vulgare), and wheat (Triticum aestivum). Here, we highlight recent advances in understanding the mechanisms underlying potential pathways of carpel development in grasses, including carpel identity determination, morphogenesis, and floral meristem determinacy. The known role of transcription factors, hormones, and miRNAs during grass carpel formation is summarized and compared with the extensively studied eudicot model plant Arabidopsis. The genetic and molecular aspects of carpel development that are conserved or diverged between grasses and eudicots are therefore discussed.

scholarly journals Endoplasmic reticulum acetyltransferases Atase1 and Atase2 differentially regulate reticulophagy, macroautophagy and cellular acetyl-CoA metabolism

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Michael J. Rigby ◽  
Alexis J. Lawton ◽  
Gulpreet Kaur ◽  
Varuna C. Banduseela ◽  
William E. Kamm ◽  
...  
Keyword(s):  
Quality Control ◽  
Secretory Pathway ◽  
Control Mechanism ◽  
Cellular Biology ◽  
Lysine Acetylation ◽  
Type Ii ◽  
Acetyl Coa ◽  
Toxic Protein ◽  
Quality Control Mechanism

AbstractNε-lysine acetylation in the ER lumen is a recently discovered quality control mechanism that ensures proteostasis within the secretory pathway. The acetyltransferase reaction is carried out by two type-II membrane proteins, ATase1/NAT8B and ATase2/NAT8. Prior studies have shown that reducing ER acetylation can induce reticulophagy, increase ER turnover, and alleviate proteotoxic states. Here, we report the generation of Atase1−/− and Atase2−/− mice and show that these two ER-based acetyltransferases play different roles in the regulation of reticulophagy and macroautophagy. Importantly, knockout of Atase1 alone results in activation of reticulophagy and rescue of the proteotoxic state associated with Alzheimer’s disease. Furthermore, loss of Atase1 or Atase2 results in widespread adaptive changes in the cell acetylome and acetyl-CoA metabolism. Overall, our study supports a divergent role of Atase1 and Atase2 in cellular biology, emphasizing ATase1 as a valid translational target for diseases characterized by toxic protein aggregation in the secretory pathway.

Role of the Cilia Membrane in Control of Microtubule Sliding

1980 ◽  
Vol 38 ◽  
pp. 612-615
Author(s):  
Edna S. Kaneshiro
Keyword(s):  
Control Mechanism ◽  
Beat Frequency ◽  
Surface Membrane ◽  
Ciliary Membrane ◽  
Ciliary Beating ◽  
Ciliary Reversal ◽  
Voltage Dependent ◽  
Reversal Mechanism ◽  
And Function

It is currently believed that ciliary beating results from microtubule sliding which is restricted in regions to cause bending. Cilia beat can be modified to bring about changes in beat frequency, cessation of beat and reversal in beat direction. In ciliated protozoans these modifications which determine swimming behavior have been shown to be related to intracellular (intraciliary) Ca2+ concentrations. The Ca2+ levels are in turn governed by the surface ciliary membrane which exhibits increased Ca2+ conductance (permeability) in response to depolarization. Mutants with altered behaviors have been isolated. Pawn mutants fail to exhibit reversal of the effective stroke of ciliary beat and therefore cannot swim backward. They lack the increased inward Ca2+ current in response to depolarizing stimuli. Both normal and pawn Paramecium made leaky to Ca2+ by Triton extrac¬tion of the surface membrane exhibit backward swimming only in reactivating solutions containing greater than IO-6 M Ca2+ Thus in pawns the ciliary reversal mechanism itself is left operational and only the control mechanism at the membrane is affected. The topographic location of voltage-dependent Ca2+ channels has been identified as a component of the ciliary mem¬brane since the inward Ca2+ conductance response is eliminated by deciliation and the return of the response occurs during cilia regeneration. Since the ciliary membrane has been impli¬cated in the control of Ca2+ levels in the cilium and therefore is the site of at least one kind of control of microtubule sliding, we have focused our attention on understanding the structure and function of the membrane.

ASPECTS IN BUILDING A COMPANY WEB-SITE AND ITS ROLE FOR THE DEVELOPMENT OF BUSINESS

2018 ◽  
pp. 117-124
Author(s):  
Petar Halachev ◽  
Victoria Radeva ◽  
Albena Nikiforova ◽  
Miglena Veneva
Keyword(s):  
Life Cycle ◽  
Web Site ◽  
The Internet ◽  
A Company ◽  
The Web ◽  
Design Construction ◽  
Made In ◽  
Site Types

This report is dedicated to the role of the web site as an important tool for presenting business on the Internet. Classification of site types has been made in terms of their application in the business and the types of structures in their construction. The Models of the Life Cycle for designing business websites are analyzed and are outlined their strengths and weaknesses. The stages in the design, construction, commissioning, and maintenance of a business website are distinguished and the activities and requirements of each stage are specified.

Aboutness

2014 ◽  
Author(s):  
Stephen Yablo
Keyword(s):  
Subject Matter ◽  
Philosophy Of Language ◽  
Mental States ◽  
Library Science ◽  
Philosophical Methodology ◽  
Major Advance ◽  
Truth Conditions ◽  
Ways Of Being ◽  
Made In

Aboutness has been studied from any number of angles. Brentano made it the defining feature of the mental. Phenomenologists try to pin down the aboutness features of particular mental states. Materialists sometimes claim to have grounded aboutness in natural regularities. Attempts have even been made, in library science and information theory, to operationalize the notion. However, it has played no real role in philosophical semantics, which is surprising. This is the first book to examine through a philosophical lens the role of subject matter in meaning. A long-standing tradition sees meaning as truth conditions, to be specified by listing the scenarios in which a sentence is true. Nothing is said about the principle of selection—about what in a scenario gets it onto the list. Subject matter is the missing link here. A sentence is true because of how matters stand where its subject matter is concerned. This book maintains that this is not just a feature of subject matter, but its essence. One indicates what a sentence is about by mapping out logical space according to its changing ways of being true or false. The notion of content that results—directed content—is brought to bear on a range of philosophical topics, including ontology, verisimilitude, knowledge, loose talk, assertive content, and philosophical methodology. The book represents a major advance in semantics and the philosophy of language.

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