Fine structure of the midventral abdominal tracheal glands in banded woolly bear caterpillars (Arctiidae: Lepidoptera)

1976 ◽  
Vol 54 (11) ◽  
pp. 1824-1839 ◽  
Author(s):  
J. R. Byers ◽  
C. F. Hinks
Keyword(s):  
Smooth Endoplasmic Reticulum ◽  
Tracheal System ◽  
Gland Cells ◽  
Functional Aspects ◽  
Secretory Cavities ◽  
Pyrrharctia Isabella ◽  
Glandular Cells ◽  
Gain Access ◽  
Membrane Infoldings

Caterpillars of Pyrrharctia isabella have four well developed tracheal glands located at the midventral anastomosis of the transverse tracheae in the third to sixth abdominal segments. The glands are approximately spherical, about 0.7 mm in diameter, and consist of a single, lobulated layer of very large glandular cells enclosing a sacculated reservoir. The haemal margin of the gland cells is characterized by extensive plasma membrane infoldings and the lumenal margin abutting the reservoir is deeply invaginated to form large microvilli-lined secretory cavities. The secretory cavities contain a lipoidal secretion that occurs in the form of fragmented plate micelles with a lamellar periodicity of about 55 Å. The secretory cavities are confluent with subcuticular spaces, from which the secretion can cross the lumenal cuticle into the reservoir and thence gain access to the exterior via the tracheal system. The most significant cytoplasmic features of the gland cells are an abundance of smooth endoplasmic reticulum and numerous small golgi complexes. Functional aspects of the cellular organization are discussed in relation to the possible role of the tracheal glands.

scholarly journals The Role of Capsid in HIV-1 Nuclear Entry

Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1425
Author(s):  
Anabel Guedán ◽  
Eve R. Caroe ◽  
Genevieve C. R. Barr ◽  
Kate N. Bishop
Keyword(s):  
Nuclear Pore ◽  
Outer Face ◽  
Nuclear Entry ◽  
Nuclear Compartment ◽  
Critical Step ◽  
Technological Advances ◽  
Dividing Cells ◽  
Hiv 1 ◽  
Gain Access

HIV-1 can infect non-dividing cells. The nuclear envelope therefore represents a barrier that HIV-1 must traverse in order to gain access to the host cell chromatin for integration. Hence, nuclear entry is a critical step in the early stages of HIV-1 replication. Following membrane fusion, the viral capsid (CA) lattice, which forms the outer face of the retroviral core, makes numerous interactions with cellular proteins that orchestrate the progress of HIV-1 through the replication cycle. The ability of CA to interact with nuclear pore proteins and other host factors around the nuclear pore determines whether nuclear entry occurs. Uncoating, the process by which the CA lattice opens and/or disassembles, is another critical step that must occur prior to integration. Both early and delayed uncoating have detrimental effects on viral infectivity. How uncoating relates to nuclear entry is currently hotly debated. Recent technological advances have led to intense discussions about the timing, location, and requirements for uncoating and have prompted the field to consider alternative uncoating scenarios that presently focus on uncoating at the nuclear pore and within the nuclear compartment. This review describes recent advances in the study of HIV-1 nuclear entry, outlines the interactions of the retroviral CA protein, and discusses the challenges of investigating HIV-1 uncoating.

scholarly journals Physiological and interactomic analysis reveals versatile functions of Arabidopsis 14-3-3 quadruple mutants in response to Fe deficiency

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jing Gao ◽  
Paula J. M. van Kleeff ◽  
Ka Wan Li ◽  
Albertus H. de Boer
Keyword(s):  
Iron Acquisition ◽  
Tca Cycle ◽  
Utilization Efficiency ◽  
Fe Deficiency ◽  
Transcriptional Level ◽  
Functional Aspects ◽  
Clear Explanation ◽  
Physiological Analysis ◽  
Proper Operation

AbstractTo date, few phenotypes have been described for Arabidopsis 14-3-3 mutants or the phenotypes showing the role of 14-3-3 in plant responding to abiotic stress. Although one member of the 14-3-3 protein family (14-3-3 omicron) was shown to be involved in the proper operation of Fe acquisition mechanisms at physiological and gene expression levels in Arabidopsis thaliana, it remains to be explored whether other members play a role in regulating iron acquisition. To more directly and effectively observe whether members of 14-3-3 non-epsilon group have a function in Fe-deficiency adaptation, three higher order quadruple KOs, kappa/lambda/phi/chi (klpc), kappa/lambda/upsilon/nu(klun), and upsilon/nu/phi/chi (unpc) were generated and studied for physiological analysis in this study. The analysis of iron-utilization efficiency, root phenotyping, and transcriptional level of Fe-responsive genes suggested that the mutant with kl background showed different phenotypes from Wt when plants suffered Fe starved, while these phenotypes were absent in the unpc mutant. Moreover, the absence of the four 14-3-3 isoforms in the klun mutant has a clear impact on the 14-3-3 interactome upon Fe deficiency. Dynamics of 14-3-3-client interactions analysis showed that 27 and 17 proteins differentially interacted with 14-3-3 in Wt and klun roots caused by Fe deficiency, respectively. Many of these Fe responsive proteins have a role in glycolysis, oxidative phosphorylation and TCA cycle, the FoF1-synthase and in the cysteine/methionine synthesis. A clear explanation for the observed phenotypes awaits a more detailed analysis of the functional aspects of 14-3-3 binding to the target proteins identified in this study.

scholarly journals Confounding Roles of ER Stress and the Unfolded Protein Response in Skeletal Muscle Atrophy

2021 ◽  
Vol 22 (5) ◽  
pp. 2567
Author(s):  
Yann S. Gallot ◽  
Kyle R. Bohnert
Keyword(s):  
Skeletal Muscle ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Smooth Endoplasmic Reticulum ◽  
Skeletal Muscle Atrophy ◽  
Unfolded Protein ◽  
The Individual ◽  
The Unfolded Protein Response ◽  
Protein Response

Skeletal muscle is an essential organ, responsible for many physiological functions such as breathing, locomotion, postural maintenance, thermoregulation, and metabolism. Interestingly, skeletal muscle is a highly plastic tissue, capable of adapting to anabolic and catabolic stimuli. Skeletal muscle contains a specialized smooth endoplasmic reticulum (ER), known as the sarcoplasmic reticulum, composed of an extensive network of tubules. In addition to the role of folding and trafficking proteins within the cell, this specialized organelle is responsible for the regulated release of calcium ions (Ca2+) into the cytoplasm to trigger a muscle contraction. Under various stimuli, such as exercise, hypoxia, imbalances in calcium levels, ER homeostasis is disturbed and the amount of misfolded and/or unfolded proteins accumulates in the ER. This accumulation of misfolded/unfolded protein causes ER stress and leads to the activation of the unfolded protein response (UPR). Interestingly, the role of the UPR in skeletal muscle has only just begun to be elucidated. Accumulating evidence suggests that ER stress and UPR markers are drastically induced in various catabolic stimuli including cachexia, denervation, nutrient deprivation, aging, and disease. Evidence indicates some of these molecules appear to be aiding the skeletal muscle in regaining homeostasis whereas others demonstrate the ability to drive the atrophy. Continued investigations into the individual molecules of this complex pathway are necessary to fully understand the mechanisms.

Quality management challenges in a dynamic reality of mergers, acquisitions and global expansion

2019 ◽  
Vol 36 (7) ◽  
pp. 1192-1211
Author(s):  
Aviva Bashan ◽  
Deganit Armon
Keyword(s):  
Quality Management ◽  
Quality Management System ◽  
Strategic Partnerships ◽  
Quality Systems ◽  
Content Type ◽  
Global Expansion ◽  
Global Quality ◽  
Functional Aspects ◽  
Strategic Role

Purpose The purpose of this paper is to highlight the challenges facing the quality management system (QMS) of parent and subsidiary companies within the dynamics of multinational mergers, acquisitions and strategic partnerships, and to present guidelines for developing a global quality strategy. Design/methodology/approach The quality systems of 18 multinational companies at different stages of mergers and acquisitions (M&A) processes and different global expansion levels were studied in depth using observations, content analyses and interviews with CEOs and operational and quality managers in parent or subsidiary companies. Findings As part of the M&A process, not enough consideration is given to the functional aspects and challenges facing the QMS of subsidiaries, and to the integration of the subsidiary QMS into the corporate QMS. The findings highlight the strategic role of the parent company in creating a corporate QMS and developing a corresponding global quality strategy. Practical implications The classification of the challenges facing the parent and subsidiary QMS forms a diagnostic tool that supports a functional preparedness for integrating quality systems, while addressing their local needs, integrating them into the global activity of the system, and utilizing the growing integrative array of resources and capabilities to achieve global value. Originality/value While M&A is perceived as a strategic topic, it has direct impact on the QMS. This study outlines a necessary conjoining of quality management and strategy, which is the key to global quality management.

Pressure cycles and the water economy of insects

1988 ◽  
Vol 318 (1190) ◽  
pp. 377-407 ◽  
Keyword(s):  
Body Temperature ◽  
Water Exchange ◽  
Vapour Phase ◽  
The Body ◽  
Tracheal System ◽  
Water Economy ◽  
Insect Wings ◽  
Pressure Cycle ◽  
Respiratory Gases

Water exchange between insects and their environment via the vapour phase includes influx and efflux components. The pressure cycle theory postulates that insects (and some other arthropods) can regulate the relative rates of influx and efflux of water vapour by modulating hydrostatic pressures at a vapour-liquid interface by compressing or expanding a sealed, gas-filled cavity. Some such cavities, like the tracheal system, could be compressed by elevated pressure in all or part of the haemocoele. Others, perhaps including the muscular rectum of flea prepupae, could be compressed by intrinsic muscles. Maddrell Insect Physiol . 8, 199 (1971)) suggested a pressure cycle mechanism of this kind to account for rectal uptake of water vapour in Thermobia but did not find it compatible with quantitative information then available. Newer evidence conforms better with the proposed mechanism. Cyclical pressure changes are of widespread occurrence in insects and have sometimes been shown to depend on water status. Evidence is reviewed for the role of the tracheal system as an avenue for net exchange of water between the insect and its environment. Because water and respiratory gases share common pathways, most published findings fail to distinguish between the conventional view that the tracheal system has evolved as a site for distribution and exchange of respiratory gases and that any water exchange occurring in it is generally incidental and nonadaptive, and the theory proposed here. The pressure cycle theory offers a supplementary explanation not incompatible with evidence so far available. The relative importance of water economy and respiratory exchange in the functioning of compressible cavities such as the tracheal system remains to be explored. Some further implications of the pressure cycle theory are discussed. Consideration is given to the possible involvement of vapour-phase transport in the internal redistribution of water within the body. It is suggested that some insect wings may constitute internal vapour-liquid exchange sites, where water can move from the body fluids to the intratracheal gas. Ambient and body temperature must influence rates of vapour-liquid mass transfer. If elevated body temperature promotes evaporative discharge of the metabolic water burden that has been shown to accumulate during flight in some large insects, their minimum threshold thoracic temperature for sustained flight may relate to the maintenance of water balance. The role of water economy in the early evolution of insect wings is considered. Pressure cycles might help to maintain water balance in surface-breathing insects living in fresh and saline waters, but the turbulence of the surface of the open sea might prevent truly marine forms from using this mechanism.

scholarly journals THE ORGANIZATION AND INNERVATION OF THE LUMINESCENT ORGAN IN A FIREFLY, PHOTURIS PENNSYLVANICA (COLEOPTERA)

1963 ◽  
Vol 16 (2) ◽  
pp. 323-359 ◽  
Author(s):  
David S. Smith
Keyword(s):  
Electron Microscope ◽  
Synaptic Vesicles ◽  
Light Emission ◽  
Nerve Endings ◽  
Tracheal Epithelium ◽  
Nerve Terminals ◽  
Tracheal System ◽  
Physiological Evidence ◽  
Effector System

The organization of the luminescent organ of an adult firefly has been studied with the electron microscope, and particular attention has been given to the disposition of nerve terminals within the organ. The cytological structure of the cells of the tracheal system, the peripheral and terminal axons, the photocytes and the cells of the dorsal ("reflecting") layer is described. Previous observations on the peripheral course of nerve branches alongside the tracheal trunks at the level of the dorsal layer and photocyte epithelium have been confirmed, and specialised nerve endings containing axoplasmic components structurally identical with "synaptic vesicles" and "neurosecretory droplets" have been identified, not in association with the surface of the photocytes, but lying between the apposed surfaces of two components of the tracheal epithelium: the tracheal end-cell and the tracheolar cell. These cytological findings are discussed in terms of available biochemical and physiological evidence concerning the mechanism of light emission in the firefly, especially with respect to the possible role of chemical "transmitter" action in triggering a response in a luminescent effector system.

scholarly journals Role of Antioxidant Vitamins in Neurogenesis

2021 ◽  
Vol 15 (1) ◽  
pp. 11
Author(s):  
Shreyashish Roy-Chowdhury ◽  
Daivat Bhavsar ◽  
Jasrita Singh ◽  
Austin Mardon
Keyword(s):  
Cell Proliferation ◽  
Neural Differentiation ◽  
Scientific Evidence ◽  
Antioxidant Vitamins ◽  
Antioxidant Vitamin ◽  
Regulatory Factor ◽  
Functional Aspects ◽  
Cycle Regulation ◽  
Inhibit Cell Proliferation

Neurogenesis is vital in the preservation of cognition. Previous studies have reported antioxidant vitamins as a key regulatory factor in neurogenesis. However, current research investigating their role is inconclusive due to the limited number of studies that have been conducted and conflicting results. This review evaluates the scientific evidence behind the potential roles of antioxidant vitamins in neurogenesis. Observations concerned with the mechanistic and functional aspects of how antioxidant vitamins modulate neurogenesis are both assessed. Vitamin A is evidently involved in cell cycle regulation and cell proliferation; vitamin C reportedly promotes neural differentiation and maturation while inhibiting neurite outgrowth; vitamin E is identified to inhibit cell proliferation while improving cell viability. Varying antioxidant vitamin concentrations have been implicated in facilitating cognition in terms of attention, memory, language, and executive function. Moreover, this review suggests a threshold antioxidant vitamin concentration that should be maintained to promote optimal levels of adult neurogenesis.

Disengagement from the State in Africa: Reflections on the Experience of Ghana and Guinea

1987 ◽  
Vol 29 (1) ◽  
pp. 106-131 ◽  
Author(s):  
Victor Azarya ◽  
Naomi Chazan
Keyword(s):  
Social Life ◽  
The State ◽  
Underlying Assumption ◽  
Center Stage ◽  
Societal Response ◽  
Role Of The State ◽  
Political Studies ◽  
Cast Doubt ◽  
Gain Access

Few questions have galvanized the attention of observers of African affairs in recent years as forcefully as the performance of the state on the continent. The debate on the nature of the state—its capabilities, weaknesses, external and societal connections, and impact—has come to occupy center stage in the field of African political studies. This overriding preoccupation emanates from the underlying assumption that the state constitutes a superior means for the fulfillment of economic and social aspirations; participation in its activities is deemed beneficial, and various sectors of society strive to associate with its institutions and gain access to its resources. Some recent works have cast doubt on this assumption, however, and the trend in the literature has been shifting towards an emphasis on the diminishing role of the state in African social life. However, even in these new studies the focus has been primarily on the state itself, its difficulties, incapacities, and failures, rather than on societal response to its actions.

Organizational access in qualitative research

2019 ◽  
Vol 14 (2) ◽  
pp. 172-193 ◽  
Author(s):  
Benjamin Nathan Alexander ◽  
Anne D. Smith
Keyword(s):  
Qualitative Research ◽  
Design Methodology ◽  
Primary Analysis ◽  
Organization Studies ◽  
Management Journal ◽  
Content Type ◽  
Systematic Assessment ◽  
Gain Access ◽  
Administrative Science

Purpose While organizational access is central to much qualitative research, little is known about how researchers secure it. The purpose of this paper is to provide a systematic assessment of this critical methodological step. Design/methodology/approach A systematic review was conducted to establish how researchers gained access to organizations for qualitative research. Access type was identified and explanatory indicators were inductively developed to illuminate how access was obtained in a sample of 216 qualitative articles published in Administrative Science Quarterly and Academy of Management Journal between 1986 and 2013. A supplemental review of 306 articles published in Organization Studies over the same period augmented the primary analysis with a broader view of published accounts of access. Findings Learning prior to entering organizations, researchers’ backgrounds, organizational insiders, and outside contacts facilitated access. The role of these factors, which served as indicators of legitimacy, varied with the type of access. In addition, the authors found that many articles provide little information about how the researchers gained access, regardless of a publication’s domicile. Originality/value This study furthers the understanding of how researchers gain access to organizations to conduct qualitative research and discusses the implications of the limited access accounts in published studies. In addition, this research provides practical guidance for authors, editors, and reviewers.

Colleters in the vegetative axis of Aechmea blanchetiana (Bromeliaceae): anatomical, ultrastructural and functional aspects

2018 ◽  
Vol 66 (5) ◽  
pp. 379 ◽  
Author(s):  
Igor Ballego-Campos ◽  
Elder Antônio Sousa Paiva
Keyword(s):  
Developmental Stages ◽  
Light And Electron Microscopy ◽  
Secretory Activity ◽  
Functional Roles ◽  
Reproductive Axis ◽  
Functional Aspects ◽  
The Family ◽  
Marginal Cells ◽  
First Time

Colleters are common among eudicotyledons, but few records exist for monocotyledons and other groups of plants. For Bromeliaceae, mucilage secretions that protect the young portions of the plant have been observed only in the reproductive axis, and little is known about the secretory systems behind this or even other kind of secretions in the family. We aimed to describe, for the first time, the occurrence of colleters associated with the vegetative shoot of Aechmea blanchetiana (Baker) L.B.Sm., and elucidate aspects of their structure, ultrastructure and secretory activity. Samples of various portions of the stem axis were prepared according to standard methods for light and electron microscopy. Colleters were found compressed in the axillary portion of leaves and in all leaf developmental stages. Secretory activity, however, was found to be restricted to young and unexpanded leaves. The colleters displayed a flattened hand-like shape formed by a multiseriate stalk and an expanded secretory portion bearing elongated marginal cells. Ultrastructural data confirmed that the secretory role of the colleters is consistent with mucilaginous secretion. The functional roles of the colleters are discussed with regard to environmental context and intrinsic features of the plant, such as the presence of a water-impounding tank.

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