Flagellar Attachment in Selected Trypanosomes

Author(s):  
J. J. Paulin

Movement in epimastigote and trypomastigote stages of trypanosomes is accomplished by planar sinusoidal beating of the anteriorly directed flagellum and associated undulating membrane. The flagellum emerges from a bottle-shaped depression, the flagellar pocket, opening on the lateral surface of the cell. The limiting cell membrane envelopes not only the body of the trypanosome but is continuous with and insheathes the flagellar axoneme forming the undulating membrane. In some species a paraxial rod parallels the axoneme from its point of emergence at the flagellar pocket and is an integral component of the undulating membrane. A portion of the flagellum may extend beyond the anterior apex of the cell as a free flagellum; the length is variable in different species of trypanosomes.

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Kristopher R. Schumacher ◽  
Aleksander S. Popel ◽  
Bahman Anvari ◽  
William E. Brownell ◽  
Alexander A. Spector

Cell membrane tethers are formed naturally (e.g., in leukocyte rolling) and experimentally to probe membrane properties. In cochlear outer hair cells, the plasma membrane is part of the trilayer lateral wall, where the membrane is attached to the cytoskeleton by a system of radial pillars. The mechanics of these cells is important to the sound amplification and frequency selectivity of the ear. We present a modeling study to simulate the membrane deflection, bending, and interaction with the cytoskeleton in the outer hair cell tether pulling experiment. In our analysis, three regions of the membrane are considered: the body of a cylindrical tether, the area where the membrane is attached and interacts with the cytoskeleton, and the transition region between the two. By using a computational method, we found the shape of the membrane in all three regions over a range of tether lengths and forces observed in experiments. We also analyze the effects of biophysical properties of the membrane, including the bending modulus and the forces of the membrane adhesion to the cytoskeleton. The model’s results provide a better understanding of the mechanics of tethers pulled from cell membranes.


Bioprinting ◽  
2021 ◽  
pp. 98-118
Author(s):  
Kenneth Douglas

Abstract: This chapter recounts bioprinting studies of skin, bone, skeletal muscle, and neuromuscular junctions. The chapter begins with a study of bioprinted skin designed to enable the creation of skin with a uniform pigmentation. The chapter relates two very different approaches to bioprinted bone: a synthetic bone called hyperelastic bone and a strategy that prints cartilage precursors to bone and then induces the conversion of the cartilage to bone by judicious choice of bioinks. Muscles move bone, and the chapter discusses an investigation of bioprinted skeletal muscle. Finally, the chapter considers an attempt to bioprint a neuromuscular junction, a synapse—a minute gap—of about 20 billionths of a meter between a motor neuron and the cell membrane of a skeletal muscle cell. A motor neuron is a nerve in the central nervous system that sends signals to the muscles of the body.


2000 ◽  
Vol 150 (1) ◽  
pp. 253-264 ◽  
Author(s):  
Teresa M. Rogalski ◽  
Gregory P. Mullen ◽  
Mary M. Gilbert ◽  
Benjamin D. Williams ◽  
Donald G. Moerman

Embryos homozygous for mutations in the unc-52, pat-2, pat-3, and unc-112 genes of C. elegans exhibit a similar Pat phenotype. Myosin and actin are not organized into sarcomeres in the body wall muscle cells of these mutants, and dense body and M-line components fail to assemble. The unc-52 (perlecan), pat-2 (α-integrin), and pat-3 (β-integrin) genes encode ECM or transmembrane proteins found at the cell–matrix adhesion sites of both dense bodies and M-lines. This study describes the identification of the unc-112 gene product, a novel, membrane-associated, intracellular protein that colocalizes with integrin at cell–matrix adhesion complexes. The 720–amino acid UNC-112 protein is homologous to Mig-2, a human protein of unknown function. These two proteins share a region of homology with talin and members of the FERM superfamily of proteins. We have determined that a functional UNC-112::GFP fusion protein colocalizes with PAT-3/β-integrin in both adult and embryonic body wall muscle. We also have determined that UNC-112 is required to organize PAT-3/β-integrin after it is integrated into the basal cell membrane, but is not required to organize UNC-52/perlecan in the basement membrane, nor for DEB-1/vinculin to localize with PAT-3/β-integrin. Furthermore, UNC-112 requires the presence of UNC-52/perlecan and PAT-3/β-integrin, but not DEB-1/vinculin to become localized to the muscle cell membrane.


Zootaxa ◽  
2007 ◽  
Vol 1466 (1) ◽  
pp. 19-34 ◽  
Author(s):  
HIROYUKI MOTOMURA ◽  
PETER R. LAST ◽  
GORDON K. YEARSLEY

Two new species of the scorpionfish genus Trachyscorpia are described on the basis of 20 and 7 specimens collected from Australasia at depths of 731–1020 m and the southwestern Indian Ocean at depths of 620–1080 m respectively. The two new species, classified into the subgenus Mesoscorpia, are distinguished from the only other member of the subgenus, T. (M.) eschmeyeri, by the following characters: the tympanic spines absent (vs. usually present in the latter), the upper-jaw lip well developed, covering the premaxillary tooth band laterally (vs. lip poorly developed, the premaxillary teeth exposed laterally), scales absent on the lateral surface of the maxilla (vs. scales present), and 4 blackish saddles on the body in preserved specimens (vs. no blackish saddles). Trachyscorpia (M.) carnomagula sp. nov. differs from T. (M.) longipedicula sp. nov. in having 57–63 scale rows in longitudinal series (vs. 50–53 in the latter). They are also distinguished by several morphometric characters, including lengths of pelvic-fin spine and soft ray, and first anal-fin spine. The subgenus Mesoscorpia is redefined. A key to the species of Trachyscorpia and comments on distribution of T. (M.) eschmeyeri are also provided.


2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Sara Novak ◽  
Damjana Drobne ◽  
Janez Valant ◽  
Primož Pelicon

There is littlein vivodata concerning the fate of ingested TiO2nanoparticles (nano-TiO2). We report here experiments aimed at assessing if ingested nano-TiO2accumulates in the digestive gland epithelium or are internalized elsewhere in the body of the terrestrial isopod crustaceans. The animals (Porcellio scaber, Isopoda, Crustacea) fed for 3, 7, or 14 days on food dosed with 100 or 1000 μg nano-TiO2showed no evidence of internalization of Ti measured by microparticle-induced X-ray emission method. The effect of ingested nanoparticles was measured by conventional toxicity measures such as feeding rate, weight change, and mortality and did not indicate any toxicity. However, cell membrane of digestive glands, measured with a modified method for assessing cell membrane stability, was affected already after 3 days of exposure to 1000 μg nano-TiO2per gram dry weight of food indicating cytotoxic potential of ingested nanoparticles. Our results confirmed hypothesis on low toxic potential and no internalization of consumed TiO2nanoparticles by a model invertebrate organism. However, cytological marker unequivocally indicated adverse effect of ingested nano-TiO2. We conclude that the isopod model system could be used for studying the fate and effect of ingested nanoparticles.


2016 ◽  
Vol 37 (3) ◽  
pp. 1431 ◽  
Author(s):  
Claudia Russo ◽  
Ana Paula F. Rodrigues Loureiro Bracarense

Reactive oxygen species (ROS), also known as free radicals, are generated during cellular respiration. Under normal conditions, the body has the ability to neutralize the effects of free radicals by using its antioxidant defenses. In the case of an imbalance between oxidants and antioxidants, free radical production exceeds the capacity of organic combustion, resulting in oxidative stress. Of all the cellular components compromised by the harmful effects of ROS, the cell membrane is the most severely affected owing to lipid peroxidation, which invariably leads to changes in the membrane structure and permeability. With lipid peroxidation of the cell membrane, some by-products can be detected and measured in tissues, blood, and other bodily fluids. The measurement of biomarkers of oxidative stress is commonly used to quantify lipid peroxidation of the cell membrane in humans, a species in which ROS can be considered as a cause or consequence of oxidative stress-related diseases. In dogs, few studies have demonstrated this correlation. The present review aims to identify current literature knowledge relating to oxidative stress diseases and their detection in dogs.


2018 ◽  
Vol 20 (4) ◽  
pp. 117-122
Author(s):  
M V Listov ◽  
A I Mamykin

Based on the analysis of simulation results of Wagner-Unverricht form polymyositis on mice of DBA/2 line, theoretical and experimental models of oxidative stress in the biological system were compared. It is shown that oxidative stress develops when the balance between the intake of free radicals and the effectiveness of the antioxidant system of the body is impaired. The main role for maintaining radical balance in the biosystem belongs to reversible electron transport through the plasma membrane during the interaction of the free radical flow with the active centres of the cell membrane. The electromagnetic nature of this interaction is underlined. The possible electrical structure of the active centre of the plasma membrane, based on the physicochemical laws of adsorption of electrically charged particles on the surface of liquid crystals, is presented and discussed in detail. The possibility of ion transport through the active centre in its interaction with the free radical is shown. It is noted that the electron transfer through the cell membrane provides the energy necessary for the non- spontaneous reverse transfer of ions in the energy-dependent component of the thermodynamic process that can form the action potential. The presence of irreversible interactions of the free radical flux with the bilipid layer of the plasma membrane in the places of defects of the liquid crystal structure is shown, which leads to the development of destructive changes. It is noted that the hypothesis of the electromagnetic nature of neurohumoral regulation presented in the paper can serve as a basis for further studies of discrete energy effects on the reflex and automatic activity of neurons, including the understanding of the mechanisms of the trigger of automatic processes in glia neurons, up to large neurons of the cerebral cortex, affecting the activity of the Central nervous system and the whole biosystem.


Author(s):  
L. Roman ◽  
S. Sidashova ◽  
I. Popova ◽  
N. Stepanova ◽  
V. Chornyi ◽  
...  

The results of the influence of the conditions of keeping Ukrainian red dairy cows on the manifestation of clinical symptoms of damage to the lateral surface of the tibia and the level of reproduction are presented. The study was conducted on the basis of an industrial dairy complex (600 dairy cows with an average productivity of 6050 kg of milk per lactation) as part of agricultural associations in Odessa region. The objects of the study were cows during lactation, which were kept loose in sections with rest boxes (where the floor was a special rubber mat with a thickness of 30 mm). Evaluation (in points) was performed on the clinical manifestation of symptoms of damage to the skin epithelium of the lateral surface of the leg, which was injured by the rubber coating of the stall compared to the level of reproduction (service period, days/%) and the severity of skin pigmentation of the body surface (selection melanism). Clinical, zootechnical, biometric methods were comprehensively applied to realize the purpose of research. Comparison of data (n = 462) visual-clinical assessment of the condition of the skin of the lateral surface of the leg, as an indicator of the adaptability of lactating cows to keep in sections with rubber flooring and the area of pigmented hair of animals of different phenotypes by coat color, showed that cows typical pigmentation, characteristic of red dairy breed (red hair occupied more than 80 % of the body surface), wound lesions of the lower leg are much less common, namely: in comparison with red-spotted animals by 28.41–15.98 %, with mostly white – by 39.03–20.23 %, respectively. Due to the negative impact of open wounds of the skin of the leg on the immunity of lactating cows, it was found that increasing the number of animals with damaged epithelium as a gateway to infection, provokes an increase in the service period in cows with predominantly white or mottled color to 140.97 and 141.07 days, which is higher by 6.74 and 6.84 days, respectively, compared with red animals (P < 0.05).


2010 ◽  
Vol 2 (2) ◽  
pp. 17-20
Author(s):  
Jayakumar LNU ◽  
Sonia LNU

Abstract Protective eyewear is integral component of Personnel protective equipments (PPE) and helps contribute to a safer work environment. Protective eyewear protocol is important in reducing contamination of the mucous membranes and skin surrounding the eyes, nose as well as injury and infections. The topic of occupational eye injuries in dentistry is one that clearly requires further study, thus, this article reviews the various eye injuries and their prevention in dentistry.


1989 ◽  
Vol 37 (1) ◽  
pp. 15 ◽  
Author(s):  
EM Burreson

Two species of Trypanosoma, three species of Haemogregarina and one species of Haemohormidium were found in 69 fishes belonging to 28 species. Trypanosoma mackerrasi, sp, nov., from Hemiscyllium ocellatum, measures 125 �m long by 18 �m wide, has no free flagellum, and has the kinetoplast located 37% of the body length from the posterior end. Trypanosoma taeniurae, sp. nov., from Taeniura lymma measures 55 �m long by 4 �m wide and has a free flagellum 9 �m long. Haemogregarina hemiscyllii was found in H. ocellatum, H. tetraodontis parasitised Diodon hystrix, and H. bigemina was found in Ecsenius bicolor. A species of Haemohorrnidium was found in Pomacentrus melanochir, but it could not be identified with certainty.


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