scholarly journals Hypoxia tolerance of giant axon-mediated escape jetting in California market squid (Doryteuthis opalescens)

2019 ◽  
Vol 222 (8) ◽  
pp. jeb198812 ◽  
Author(s):  
Diana H. Li ◽  
William F. Gilly
Keyword(s):  
Giant Axon ◽  
Hypoxia Tolerance ◽  
Doryteuthis Opalescens

Formation of paired helical filaments in Alzheimer's disease

1984 ◽  
Vol 42 ◽  
pp. 302-303
Author(s):  
J. Metuzals ◽  
D. F. Clapin ◽  
V. Montpetit
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Frontal Lobe ◽  
Giant Axon ◽  
Paired Helical Filaments ◽  
Normal Brain ◽  
Protein Assemblies ◽  
Electron Microscopic ◽  
Helical Symmetry ◽  
Structural Levels

Information on the conformation of paired helical filaments (PHF) and the neurofilamentous (NF) network is essential for an understanding of the mechanisms involved in the formation of the primary lesions of Alzheimer's disease (AD): tangles and plaques. The structural and chemical relationships between the NF and the PHF have to be clarified in order to discover the etiological factors of this disease. We are investigating by stereo electron microscopic and biochemical techniques frontal lobe biopsies from patients with AD and squid giant axon preparations. The helical nature of the lesion in AD is related to pathological alterations of basic properties of the nervous system due to the helical symmetry that exists at all hierarchic structural levels in the normal brain. Because of this helical symmetry of NF protein assemblies and PHF, the employment of structure reconstruction techniques to determine the conformation, particularly the handedness of these structures, is most promising. Figs. 1-3 are frontal lobe biopsies.

Neurofilaments and Paired Helical Filaments

1985 ◽  
Vol 43 ◽  
pp. 740-743
Author(s):  
J. Metuzals
Keyword(s):  
Animal Model ◽  
Posttranslational Modifications ◽  
Posttranslational Modification ◽  
Giant Axon ◽  
Paired Helical Filaments ◽  
Squid Giant Axon ◽  
In Vitro Experiments ◽  
Thin Sections ◽  
Structural Relationships

It has been demonstrated that the neurofibrillary tangles in biopsies of Alzheimer patients, composed of typical paired helical filaments (PHF), consist also of typical neurofilaments (NF) and 15nm wide filaments. Close structural relationships, and even continuity between NF and PHF, have been observed. In this paper, such relationships are investigated from the standpoint that the PHF are formed through posttranslational modifications of NF. To investigate the validity of the posttranslational modification hypothesis of PHF formation, we have identified in thin sections from frontal lobe biopsies of Alzheimer patients all existing conformations of NF and PHF and ordered these conformations in a hypothetical sequence. However, only experiments with animal model preparations will prove or disprove the validity of the interpretations of static structural observations made on patients. For this purpose, the results of in vitro experiments with the squid giant axon preparations are compared with those obtained from human patients. This approach is essential in discovering etiological factors of Alzheimer's disease and its early diagnosis.

Hypoxia Tolerance in Twelve Species of East African Cichlids: Potential for Low Oxygen Refugia in Lake Victoria

1995 ◽  
Vol 9 (5) ◽  
pp. 1274-1288 ◽  
Author(s):  
LAUREN J. CHAPMAN ◽  
LESLIE S. KAUFMAN ◽  
COLIN A. CHAPMAN ◽  
F. ELLIS MCKENZIE
Keyword(s):  
Lake Victoria ◽  
Hypoxia Tolerance ◽  
Low Oxygen ◽  
East African ◽  
East African Cichlids ◽  
African Cichlids

scholarly journals Physiological resilience of pink salmon to naturally occurring ocean acidification

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Andrea Y Frommel ◽  
Justin Carless ◽  
Brian P V Hunt ◽  
Colin J Brauner
Keyword(s):  
British Columbia ◽  
Elevated Co2 ◽  
Condition Factor ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Hypoxia Tolerance ◽  
High Co2 ◽  
The North ◽  
Naturally Occurring ◽  
Co2 Levels

Abstract Pacific salmon stocks are in decline with climate change named as a contributing factor. The North Pacific coast of British Columbia is characterized by strong temporal and spatial heterogeneity in ocean conditions with upwelling events elevating CO2 levels up to 10-fold those of pre-industrial global averages. Early life stages of pink salmon have been shown to be affected by these CO2 levels, and juveniles naturally migrate through regions of high CO2 during the energetically costly phase of smoltification. To investigate the physiological response of out-migrating wild juvenile pink salmon to these naturally occurring elevated CO2 levels, we captured fish in Georgia Strait, British Columbia and transported them to a marine lab (Hakai Institute, Quadra Island) where fish were exposed to one of three CO2 levels (850, 1500 and 2000 μatm CO2) for 2 weeks. At ½, 1 and 2 weeks of exposure, we measured their weight and length to calculate condition factor (Fulton’s K), as well as haematocrit and plasma [Cl−]. At each of these times, two additional stressors were imposed (hypoxia and temperature) to provide further insight into their physiological condition. Juvenile pink salmon were largely robust to elevated CO2 concentrations up to 2000 μatm CO2, with no mortality or change in condition factor over the 2-week exposure duration. After 1 week of exposure, temperature and hypoxia tolerance were significantly reduced in high CO2, an effect that did not persist to 2 weeks of exposure. Haematocrit was increased by 20% after 2 weeks in the CO2 treatments relative to the initial measurements, while plasma [Cl−] was not significantly different. Taken together, these data indicate that juvenile pink salmon are quite resilient to naturally occurring high CO2 levels during their ocean outmigration.

Hypoxia Tolerance, Nitric Oxide, and Nitrite: Lessons From Extreme Animals

Physiology ◽  
2015 ◽  
Vol 30 (2) ◽  
pp. 116-126 ◽  
Author(s):  
Angela Fago ◽  
Frank B. Jensen
Keyword(s):  
Nitric Oxide ◽  
Marine Mammals ◽  
Crucian Carp ◽  
Physiological Responses ◽  
Oxygen Deprivation ◽  
Hypoxia Tolerance ◽  
Carassius Carassius ◽  
Slider Turtle ◽  
Total Lack ◽  
Crucian Carp Carassius Carassius

Among vertebrates able to tolerate periods of oxygen deprivation, the painted and red-eared slider turtles ( Chrysemys picta and Trachemys scripta) and the crucian carp ( Carassius carassius) are the most extreme and can survive even months of total lack of oxygen during winter. The key to hypoxia survival resides in concerted physiological responses, including strong metabolic depression, protection against oxidative damage and–in air-breathing animals–redistribution of blood flow. Each of these responses is known to be tightly regulated by nitric oxide (NO) and during hypoxia by its metabolite nitrite. The aim of this review is to highlight recent work illustrating the widespread roles of NO and nitrite in the tolerance to extreme oxygen deprivation, in particular in the red-eared slider turtle and crucian carp, but also in diving marine mammals. The emerging picture underscores the importance of NO and nitrite signaling in the adaptive response to hypoxia in vertebrate animals.

Injury-induced vesiculation and membrane redistribution in squid giant axon

1990 ◽  
Vol 1023 (3) ◽  
pp. 421-435 ◽  
Author(s):  
Harvey M. Fishman ◽  
Kirti P. Tewari ◽  
Philip G. Stein
Keyword(s):  
Giant Axon ◽  
Squid Giant Axon

scholarly journals Theoretical Effect of Temperature on Threshold in the Hodgkin-Huxley Nerve Model

1966 ◽  
Vol 49 (5) ◽  
pp. 989-1005 ◽  
Author(s):  
Richard Fitzhugh
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Giant Axon ◽  
Temperature Curve ◽  
Effect Of Temperature ◽  
Threshold Temperature ◽  
Ionic Conductances ◽  
And Shifts ◽  
The Right ◽  
Increasing Temperature

In the squid giant axon, Sjodin and Mullins (1958), using 1 msec duration pulses, found a decrease of threshold with increasing temperature, while Guttman (1962), using 100 msec pulses, found an increase. Both results are qualitatively predicted by the Hodgkin-Huxley model. The threshold vs. temperature curve varies so much with the assumptions made regarding the temperature-dependence of the membrane ionic conductances that quantitative comparison between theory and experiment is not yet possible. For very short pulses, increasing temperature has two effects. (1) At lower temperatures the decrease of relaxation time of Na activation (m) relative to the electrical (RC) relaxation time favors excitation and decreases threshold. (2) For higher temperatures, effect (1) saturates, but the decreasing relaxation times of Na inactivation (h) and K activation (n) factor accommodation and increased threshold. The result is a U-shaped threshold temperature curve. R. Guttman has obtained such U-shaped curves for 50 µsec pulses. Assuming higher ionic conductances decreases the electrical relaxation time and shifts the curve to the right along the temperature axis. Making the conductances increase with temperature flattens the curve. Using very long pulses favors effect (2) over (1) and makes threshold increase monotonically with temperature.

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