Mechanisms of Adaptation to Cold

AbstractPopulation genomic analyses of high-altitude humans and other vertebrates have identified numerous candidate genes for hypoxia adaptation, and the physiological pathways implicated by such analyses suggest testable hypotheses about underlying mechanisms. Studies of highland natives that integrate genomic data with experimental measures of physiological performance capacities and subordinate traits are revealing associations between genotypes (e.g., hypoxia-inducible factor gene variants) and hypoxia-responsive phenotypes. The subsequent search for causal mechanisms is complicated by the fact that observed genotypic associations with hypoxia-induced phenotypes may reflect second-order consequences of selection-mediated changes in other (unmeasured) traits that are coupled with the focal trait via feedback regulation. Manipulative experiments to decipher circuits of feedback control and patterns of phenotypic integration can help identify causal relationships that underlie observed genotype–phenotype associations. Such experiments are critical for correct inferences about phenotypic targets of selection and mechanisms of adaptation.

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Growth, Development and Innate Capacity for Increase in Aphytis Chrysomphali Mercet and A. Melinus Debach, Parasites of California Red Scale, Aonidiella Aurantii (Mask.), In Relation to Temperature.

Australian Journal of Zoology ◽

10.1071/zo9740213 ◽

1974 ◽

Vol 22 (2) ◽

pp. 213 ◽

Cited By ~ 31

Author(s):

I Abdelrahman

Keyword(s):

Negative Relationship ◽

Differential Mortality ◽

Female Progeny ◽

Annual Fluctuation ◽

Adaptation To Cold ◽

Rate Of Increase ◽

Total Progeny ◽

Searching Ability ◽

Pupal Mortality ◽

Threshold Of Development

A, melinus produced more female progeny and more than twice as many total progeny as A. chrysomphali; it also destroyed almost twice as many hosts through oviposition and mutiliation. A. chrysomphali had a longer post-oviposition period than A. melinus, especially at 30�C. The proportion of single progeny in a host was higher for A, chrysomphali than for A. melinus at all temperatures, and was related to temperature positively in A. chrysomphali and inversely in A. melinus. Large old female A. melinus produced only males at the end of their lives; they did not mate at that stage when offered males, not because they were aged but because they mate only once in their lives. As temperature decreased, female A. melznus ceased producing females earlier, probably because temperature affected either longevity of sperms or the mechanism controlling their release. Differential mortality, temperature, and age of mothers all influenced sex ratio. Pupal mortality was inversely related to temperature within the observed range 20-30�C; in female pupae of A. chrysomphali it was lower than that in either female or male pupae of A. melinus; it was higher in male than female pupae in A. melinus. A. melinus lived longer than A. chrysomphali at all temperatures. Duration of development was longer for A. chrysomphali than for A. melinus at 30�C, but shorter at 20 and 25�C. The threshold of development was 8.5C for A. chrysomphali and 11C for A. melinus. A. chrysomphali had a higher rm at 20 and 25�C than A. melinus, but much lower at 30�C. The highest rate of increase was at > 30�C for A. melinus, and at about 25�C for A. chrysomphali. The rm of the parasites was 3.1-5.0 times that of red scale, depending on parasite species and temperature. A. chrysomphali is smaller than A. melinus, and from the positive relationship between adaptation to cold and speed of development, and the negative relationship between speed of development and size, a negative relationship between size and adaptation to cold within Aphytis spp. may be postulated. A. chrysomphali is more adapted to cold and less to heat than A. melinus. This explains the seasonal and annual fluctuation in their relative abundance in southern Australia. The species would complement each other in controlling red scale; from the data presented here it is possible that Aphytis spp. in Australia may have evolved into more efficient control agents of red scale than elsewhere. Knowledge on the searching ability of Aphytis at different host densities is wanting.

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Identification of Biomolecules Involved in the Adaptation to the Environment of Cold-Loving Microorganisms and Metabolic Pathways for Their Production

Biomolecules ◽

10.3390/biom11081155 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1155

Author(s):

Eva Garcia-Lopez ◽

Paula Alcazar ◽

Cristina Cid

Keyword(s):

Metabolic Pathways ◽

Extracellular Polymeric Substances ◽

Molecular Mechanisms ◽

Current Knowledge ◽

Analytical Techniques ◽

Light Protection ◽

Domains Of Life ◽

Mechanisms Of Adaptation ◽

Resistance To Stress ◽

Function Discovery

Cold-loving microorganisms of all three domains of life have unique and special abilities that allow them to live in harsh environments. They have acquired structural and molecular mechanisms of adaptation to the cold that include the production of anti-freeze proteins, carbohydrate-based extracellular polymeric substances and lipids which serve as cryo- and osmoprotectants by maintaining the fluidity of their membranes. They also produce a wide diversity of pigmented molecules to obtain energy, carry out photosynthesis, increase their resistance to stress and provide them with ultraviolet light protection. Recently developed analytical techniques have been applied as high-throughoutput technologies for function discovery and for reconstructing functional networks in psychrophiles. Among them, omics deserve special mention, such as genomics, transcriptomics, proteomics, glycomics, lipidomics and metabolomics. These techniques have allowed the identification of microorganisms and the study of their biogeochemical activities. They have also made it possible to infer their metabolic capacities and identify the biomolecules that are parts of their structures or that they secrete into the environment, which can be useful in various fields of biotechnology. This Review summarizes current knowledge on psychrophiles as sources of biomolecules and the metabolic pathways for their production. New strategies and next-generation approaches are needed to increase the chances of discovering new biomolecules.

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Advances in Comparative and Environmental Physiology, 4. Animal Adaptation to Cold. Edited byLawrenceC. H.Wang. Pp. 441. (Springer-Verlag, Berlin, 1989.) DM 198.00 hardback. ISBN 3 540 50301 3

Experimental Physiology ◽

10.1113/expphysiol.1998.sp004178 ◽

1990 ◽

Vol 75 (3) ◽

pp. 435-436

Author(s):

John Bligh

Keyword(s):

Environmental Physiology ◽

Adaptation To Cold

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Mechanisms of Adaptation to Nitrosative Stress in Bacillus subtilis

Journal of Bacteriology ◽

10.1128/jb.01782-06 ◽

2007 ◽

Vol 189 (8) ◽

pp. 3063-3071 ◽

Cited By ~ 50

Author(s):

Annika Rogstam ◽

Jonas T. Larsson ◽

Peter Kjelgaard ◽

Claes von Wachenfeldt

Keyword(s):

Bacillus Subtilis ◽

Stress Proteins ◽

Nitrosative Stress ◽

Vital Role ◽

Null Mutant ◽

Truncated Hemoglobin ◽

Sigma B ◽

Nitrosonium Cation ◽

Mechanisms Of Adaptation ◽

Increased Sensitivity

ABSTRACT Bacteria use a number of mechanisms for coping with the toxic effects exerted by nitric oxide (NO) and its derivatives. Here we show that the flavohemoglobin encoded by the hmp gene has a vital role in an adaptive response to protect the soil bacterium Bacillus subtilis from nitrosative stress. We further show that nitrosative stress induced by the nitrosonium cation donor sodium nitroprusside (SNP) leads to deactivation of the transcriptional repressor NsrR, resulting in derepression of hmp. Nitrosative stress induces the sigma B-controlled general stress regulon. However, a sigB null mutant did not show increased sensitivity to SNP, suggesting that the sigma B-dependent stress proteins are involved in a nonspecific protection against stress whereas the Hmp flavohemoglobin plays a central role in detoxification. Mutations in the yjbIH operon, which encodes a truncated hemoglobin (YjbI) and a predicted 34-kDa cytosolic protein of unknown function (YjbH), rendered B. subtilis hypersensitive to SNP, suggesting roles in nitrosative stress management.

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MECHANISMS OF ADAPTATION OF THE LEFT VENTRICLE TO MUSCULAR EXERCISE

PEDIATRICS ◽

10.1542/peds.32.4.660 ◽

1963 ◽

Vol 32 (4) ◽

pp. 660-670

Author(s):

Jere H. Mitchell

Keyword(s):

Cardiac Output ◽

Left Ventricle ◽

Stroke Volume ◽

Pulse Rate ◽

Individual Factors ◽

Normal Male ◽

Oxygen Intake ◽

Mechanisms Of Adaptation ◽

Male Subjects ◽

Oxygen Difference

THE mechanisms of adaptation of the left ventricle to the demands of muscular exercise have intrigued cardiovascular physiologists for many years. Although highly complex, these adaptive mechanisms are more and more susceptible to analysis and quantification. In this presentation I will attempt to identify some of the individual factors which appear to be important in the response of the left ventricle to exercise, beginning with data obtained from experiments on conscious normal male subjects and proceeding to experiments performed on dog preparations in which individual factors were controlled and analyzed. The changes in oxygen intake, cardiac output, estimated arteriovenous oxygen difference, pulse rate and estimated mean stroke volume were determined in 15 normal male subjects during rest in the standing position and during treadmill exercise at the maximal oxygen intake level. Oxygen intake was obtained from the volume and composition of expired air, cardiac output by the dye dilution technique, and pulse rate from the electrocardiogram. Estimated arteriovenous oxygen difference was obtained by dividing the oxygen intake by the cardiac output (Fick principle) and estimated mean stroke volume by dividing the cardiac output by the heart rate. The data are shown in Figure 1. Oxygen intake increased from a mean value of 0.34 at rest to a maximal value of 3.22 L./min. The corresponding mean values for cardiac output were 5.4 and 23.4 L./min. and for arteriovenous oxygen difference were 6.5 and 14.3 ml./100 ml. Thus, as oxygen intake increased 9.5 times, the cardiac output increased 4.3 times and the arterio venous oxygen difference 2.2 times.

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