Aspects of the Physiology of Terrestrial Life in Amphibious Fishes

1970 ◽  
Vol 53 (3) ◽  
pp. 559-572 ◽  
Author(s):  
MALCOLM S. GORDON ◽  
SIEGMUND FISCHER ◽  
EDUARDO TARIFEÑO S.
Keyword(s):  
Thermal Stresses ◽  
Control Level ◽  
Severe Dehydration ◽  
Evaporative Water ◽  
Central Chile ◽  
Lethal Temperatures ◽  
Physiological Adaptations ◽  
Terrestrial Life ◽  
Amphibious Fishes ◽  
Systemic Accumulation

1. A study has been made of major aspects of the physiological adaptations for terrestrial life possessed by the amphibious clingfish, Sicyases sanguineus, on the coast of central Chile. 2. These fish can survive for more than 1½ days out of water, if not exposed to severe dehydration or thermal stresses. Rates of evaporative water loss while out of water are low. Upper lethal temperatures are also low, reflecting the uniformly cool water temperatures of their environment. In nature the fish rarely leave areas in which they are frequently washed over by waves. 3. These fish demonstrate an unusual combination of metabolic and cardiovascular adjustments to emersion. Metabolic rates (oxygen consumption) of small (1-5 g weight) fish are higher out of water than in water. Larger fish show a pattern of intermittent oxygen uptake when out of water. Heart rates respond to emersion (and associated cessation of breathing movements) in the pattern of the diving syndrome. Lactic acid concentrations in the blood gradually increase above control levels during the first few hours of emersion, then remain constant at about x 3 control level. There is no indication of peripheral vascular shutdown during emersion. 4. Emersion produces a marked shift towards ureotelism in waste nitrogen production. There appears to be no systemic accumulation of ammonia during emersion. 5. The generality of the results, and also their physiological significance, are discussed.

Aspects of the Physiology of Terrestrial Life in Amphibious Fishes

1969 ◽  
Vol 50 (1) ◽  
pp. 141-149 ◽  
Author(s):  
MALCOLM S. GORDON ◽  
INGE BOËTIUS ◽  
DAVID H. EVANS ◽  
ROSEMARY McCARTHY ◽  
LARRY C. OGLESBY
Keyword(s):  
Thermal Stresses ◽  
Severe Dehydration ◽  
Evaporative Water ◽  
Lethal Temperatures ◽  
Physiological Adaptations ◽  
Urea Production ◽  
Terrestrial Life ◽  
Production Increase ◽  
Amphibious Fishes ◽  
Environmental Temperatures

1. A study has been carried out of major aspects of the physiological adaptations for terrestrial life possessed by the amphibious mudskipper fish, Periophthalmus sobrinus, on the island of Nosy Bé, Madagascar. 2. These fish can survive for approximately 1½ days out of water, if not exposed to severe dehydration or thermal stresses. Evaporative water-loss rates while out of water are relatively low. Upper lethal temperatures are only a few degrees above normal midday environmental temperatures. 3. These fish lack the symptoms of the ‘diving syndrome’. Metabolic rates (oxygen consumption), heart rates, and blood lactic acid concentrations are not affected by shifts of fish between water and air. 4. Rates of ammonia and urea production increase in fish out of water. The ratio of urea/ammonia also increases. 5. The generality of the results, also their physiological significance, are discussed.

scholarly journals Environmental temperatures shape thermal physiology as well as diversification and genome-wide substitution rates in lizards

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Joan Garcia-Porta ◽  
Iker Irisarri ◽  
Martin Kirchner ◽  
Ariel Rodríguez ◽  
Sebastian Kirchhof ◽  
...  
Keyword(s):  
Climatic Conditions ◽  
Evaporative Water ◽  
Substitution Rates ◽  
Preferred Temperature ◽  
Genome Wide ◽  
A Genome ◽  
Physiological Adaptations ◽  
Preferred Temperatures ◽  
Maximum Temperatures ◽  
Species Specific

Abstract Climatic conditions changing over time and space shape the evolution of organisms at multiple levels, including temperate lizards in the family Lacertidae. Here we reconstruct a dated phylogenetic tree of 262 lacertid species based on a supermatrix relying on novel phylogenomic datasets and fossil calibrations. Diversification of lacertids was accompanied by an increasing disparity among occupied bioclimatic niches, especially in the last 10 Ma, during a period of progressive global cooling. Temperate species also underwent a genome-wide slowdown in molecular substitution rates compared to tropical and desert-adapted lacertids. Evaporative water loss and preferred temperature are correlated with bioclimatic parameters, indicating physiological adaptations to climate. Tropical, but also some populations of cool-adapted species experience maximum temperatures close to their preferred temperatures. We hypothesize these species-specific physiological preferences may constitute a handicap to prevail under rapid global warming, and contribute to explaining local lizard extinctions in cool and humid climates.

scholarly journals A Gastrointestinal Metagenomic Study On Mudskippers Supports Their Terrestrial Adaptation

2022 ◽  
Author(s):  
Bo Dong ◽  
Jing Liu ◽  
Bing Chen ◽  
Yuqi Huang ◽  
Peng Ai ◽  
...  
Keyword(s):  
Fish Species ◽  
Life Style ◽  
Potential Functions ◽  
Metagenomic Data ◽  
Literature Mining ◽  
Microbial Composition ◽  
Terrestrial Life ◽  
Metagenomic Study ◽  
Amphibious Fishes ◽  
Genome Level

Abstract -Purpose: The adaptability of blue-spotted mudskipper (Boleophthalmus Periophthalmodon; BP) and giant-fin mudskipper (Periophthalmus magnuspinnatus; PM), has been previously reported at the genome level to explain their amphibious life. However, the roles of GI microbiota in their adaptation to the terrestrial life are worth exploring. -Methods: In this study, we mainly utilized metagenomic data from these two representative mudskippers and typical aquicolous fish species to obtain microbial composition, diversity, abundance and potential functions of GI microbiota for comparisons between amphibious and aquicolous fishes. Meanwhile, we summarized the GI microbiota results of representative seawater fishes, freshwater fishes, amphibians, and terrestrial animals by literature mining for comparing those of the mudskippers. -Result: Interestingly the content for each dominant phylum was strikingly different among BP, PM and aquicolous fishes. We also observed that the profile of GI microbiota in mudskippers owned the typical bacterial families for the terrestrial animals, (freshwater and seawater) fishes, and amphibians at the same time, which is consistent with their life style of water-to-land and freshwater to seawater transition. More interestingly, certain bacteria strains like S24-7, previously thought to be specific in terrestrial animals, were also identified in both BP and PM. -Conclusion: The various composite and diversity of mudskipper GI microflora are therefore considered to conduce to their terrestrial adaptation in these amphibious fishes.

Distributed Parameter Optimum Control of a Nuclear Rocket With Thermal Stress Constraints

1967 ◽  
Vol 89 (2) ◽  
pp. 300-306 ◽  
Author(s):  
D. L. Briggs ◽  
C. N. Shen
Keyword(s):  
Optimal Control ◽  
Thermal Stress ◽  
Flow Rate ◽  
Thermal Stresses ◽  
Control Level ◽  
Control Program ◽  
Bilinear System ◽  
Stress Constraints ◽  
Stress Constraint ◽  
Nuclear Rocket

The problem considered here is that of controlling the flow rate through a nuclear rocket such that temperature gradients in the fuel elements, and the corresponding thermal stresses produced, do not exceed specified values. The desired control program is that which takes the system from steady-state conditions at a given flow rate to a higher, specified flow rate in minimum time without violating the thermal stress constraints. The system equations here are a pair of coupled, first-order, bilinear, partial differential equations and the thermal stress constraint is proportional to a product of state and control variables. By analyzing both the solution for a step in control and the coupling between control level and time response in the bilinear system, the form of the optimal control is deduced. It is shown how the optimal control law can be generated using a digital computer. Numerical results are given.

Homochirality as the Signature of Extra-Terrestrial Life

1997 ◽  
Vol 161 ◽  
pp. 505-510
Author(s):  
Alexandra J. MacDermott ◽  
Laurence D. Barron ◽  
Andrè Brack ◽  
Thomas Buhse ◽  
John R. Cronin ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Optical Rotation ◽  
Physical Origin ◽  
Natural Choice ◽  
Rosetta Mission ◽  
Terrestrial Life ◽  
Subsurface Layers ◽  
Solar System Bodies ◽  
Origin Of Homochirality

AbstractThe most characteristic hallmark of life is its homochirality: all biomolecules are usually of one hand, e.g. on Earth life uses only L-amino acids for protein synthesis and not their D mirror images. We therefore suggest that a search for extra-terrestrial life can be approached as a Search for Extra- Terrestrial Homochirality (SETH). The natural choice for a SETH instrument is optical rotation, and we describe a novel miniaturized space polarimeter, called the SETH Cigar, which could be used to detect optical rotation as the homochiral signature of life on other planets. Moving parts are avoided by replacing the normal rotating polarizer by multiple fixed polarizers at different angles as in the eye of the bee. We believe that homochirality may be found in the subsurface layers on Mars as a relic of extinct life, and on other solar system bodies as a sign of advanced pre-biotic chemistry. We discuss the chiral GC-MS planned for the Roland lander of the Rosetta mission to a comet and conclude with theories of the physical origin of homochirality.

Deformation at interfaces of Ti-6Al-4V/SiC fiber composites

1992 ◽  
Vol 50 (1) ◽  
pp. 158-159
Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy
Keyword(s):  
Thermal Stresses ◽  
Load Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Hot Isostatic Pressing ◽  
Matrix Composites ◽  
Ongoing Research ◽  
Aerospace Applications ◽  
Sic Fiber ◽  
The Matrix ◽  
Intermetallic Matrix Composites

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.

Arabidopsis 4-COUMAROYL-COA LIGASE 8 contributes to the biosynthesis of the benzenoid ring of coenzyme Q in peroxisomes

2019 ◽  
Vol 476 (22) ◽  
pp. 3521-3532
Author(s):  
Eric Soubeyrand ◽  
Megan Kelly ◽  
Shea A. Keene ◽  
Ann C. Bernert ◽  
Scott Latimer ◽  
...  
Keyword(s):  
Oxidative Metabolism ◽  
Time Course ◽  
Reverse Genetics ◽  
De Novo ◽  
Coenzyme Q ◽  
Control Level ◽  
Wild Type ◽  
Fluorescent Reporters ◽  
Coa Ligase ◽  
Peroxisomal Targeting

Plants have evolved the ability to derive the benzenoid moiety of the respiratory cofactor and antioxidant, ubiquinone (coenzyme Q), either from the β-oxidative metabolism of p-coumarate or from the peroxidative cleavage of kaempferol. Here, isotopic feeding assays, gene co-expression analysis and reverse genetics identified Arabidopsis 4-COUMARATE-COA LIGASE 8 (4-CL8; At5g38120) as a contributor to the β-oxidation of p-coumarate for ubiquinone biosynthesis. The enzyme is part of the same clade (V) of acyl-activating enzymes than At4g19010, a p-coumarate CoA ligase known to play a central role in the conversion of p-coumarate into 4-hydroxybenzoate. A 4-cl8 T-DNA knockout displayed a 20% decrease in ubiquinone content compared with wild-type plants, while 4-CL8 overexpression boosted ubiquinone content up to 150% of the control level. Similarly, the isotopic enrichment of ubiquinone's ring was decreased by 28% in the 4-cl8 knockout as compared with wild-type controls when Phe-[Ring-13C6] was fed to the plants. This metabolic blockage could be bypassed via the exogenous supply of 4-hydroxybenzoate, the product of p-coumarate β-oxidation. Arabidopsis 4-CL8 displays a canonical peroxisomal targeting sequence type 1, and confocal microscopy experiments using fused fluorescent reporters demonstrated that this enzyme is imported into peroxisomes. Time course feeding assays using Phe-[Ring-13C6] in a series of Arabidopsis single and double knockouts blocked in the β-oxidative metabolism of p-coumarate (4-cl8; at4g19010; at4g19010 × 4-cl8), flavonol biosynthesis (flavanone-3-hydroxylase), or both (at4g19010 × flavanone-3-hydroxylase) indicated that continuous high light treatments (500 µE m−2 s−1; 24 h) markedly stimulated the de novo biosynthesis of ubiquinone independently of kaempferol catabolism.

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