cold adaptation Dotaz Zobrazit nápovědu
Cold-loving microorganisms developed numerous adaptation mechanisms allowing them to survive in extremely cold habitats, such as adaptation of the cell membrane. The focus of this study was on the membrane fatty acids of Antarctic Flavobacterium spp., and their adaptation response to cold-stress. Fatty acids and cold-response of Antarctic flavobacteria was also compared to mesophilic and thermophilic members of the genus Flavobacterium. The results showed that the psychrophiles produced more types of major fatty acids than meso- and thermophilic members of this genus, namely C15:1 iso G, C15:0 iso, C15:0 anteiso, C15:1ω6c, C15:0 iso 3OH, C17:1ω6c, C16:0 iso 3OH and C17:0 iso 3OH, summed features 3 (C16:1ω7cand/or C16:1ω6c) and 9 (C16:0 10-methyl and/or C17:1 iso ω9c). It was shown that the cell membrane of psychrophiles was composed mainly of branched and unsaturated fatty acids. The results also implied that Antarctic flavobacteria mainly used two mechanisms of membrane fluidity alteration in their cold-adaptive response. The first mechanism was based on unsaturation of fatty acids, and the second mechanism on de novo synthesis of branched fatty acids. The alteration of the cell membrane was shown to be similar for all thermotypes of members of the genus Flavobacterium.
- Klíčová slova
- Adaptation, Antarctic bacteria, Cell membrane, Cold-shock, Fatty acids, Flavobacterium,
- MeSH
- Flavobacterium fyziologie MeSH
- fyziologická adaptace * MeSH
- mastné kyseliny metabolismus MeSH
- nízká teplota * MeSH
- reprodukovatelnost výsledků MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Antarktida MeSH
- Názvy látek
- mastné kyseliny MeSH
The impact of repeated exposure to cold and cold adaptation on human cardiovascular health is not fully understood. The aim of the study was to determine the effect of cold adaptation on cardiovascular risk factors, thyroid hormones and the capacity of humans to reset the damaging effect of oxidative stress. Ten well cold-adapted winter swimmers (CA) and 16 non-adapted controls (CON) were enroled in this experiment to test whether cold adaptation could influence the parameters of lipoprotein metabolism, cholesterol efflux capacity (CEC), homocysteine, thyroid hormones, antioxidant defence markers (reduced glutathione (GSH), glutathione peroxidase 1 (GPX1), glutathione reductase (GR), catalase (CAT) and paraoxonase 1 (PON1)) and oxidative stress markers (concentration of conjugated dienes (CD)). A decreased apolipoprotein B/apolipoprotein A1 (ApoB/ApoA1) ratio was found in the CA group (p<0.05), but other lipoprotein parameters, including CEC, did not differ significantly. Plasma homocysteine was lower in CA subjects in comparison with controls (p<0.05). Higher triiodothyronine (T3) values were observed in the CA compared to the CON (p<0.05) group, but TSH and other thyroid hormones did not differ between both groups. CA subjects had lower activity of GPX1 (p<0.05), lower concentrations of CD (p<0.05) and increased activities of PON1 (p<0.001) compared to CON subjects. A trend for decreased activity of CAT (p=0.06) in CA compared to CON groups was also observed, but GSH levels did not differ significantly. Zn concentration was higher in the CA group than in the CON group (p<0.001). Human cold adaptation can influence oxidative stress markers. Trends towards the improvement of cardiovascular risk factors in cold-adapted subjects also indicate the positive effect of cold adaptation on cardio-protective mechanisms.
- Klíčová slova
- Antioxidant enzymes, Antioxidants, Atherosclerosis, Cold adaptation, Lipoproteins,
- MeSH
- antioxidancia metabolismus MeSH
- ateroskleróza epidemiologie patofyziologie MeSH
- dospělí MeSH
- fyziologická adaptace fyziologie MeSH
- hormony štítné žlázy metabolismus MeSH
- hormony krev MeSH
- kardiovaskulární nemoci epidemiologie patofyziologie MeSH
- kultivované buňky MeSH
- lidé středního věku MeSH
- lidé MeSH
- metabolismus lipidů MeSH
- nízká teplota * MeSH
- oxidační stres fyziologie MeSH
- plavání MeSH
- zinek metabolismus MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- antioxidancia MeSH
- hormony štítné žlázy MeSH
- hormony MeSH
- zinek MeSH
Membrane fluidity adaptation to the low growth temperature in Bacillus subtilis involves two distinct mechanisms: (1) long-term adaptation accomplished by increasing the ratio of anteiso- to iso-branched fatty acids and (2) rapid desaturation of fatty acid chains in existing phospholipids by induction of fatty acid desaturase after cold shock. In this work we studied the effect of medium composition on cold adaptation of membrane fluidity. Bacillus subtilis was cultivated at optimum (40 degrees C) and low (20 degrees C) temperatures in complex medium with glucose or in mineral medium with either glucose or glycerol. Cold adaptation was characterized by fatty acid analysis and by measuring the midpoint of phospholipid phase transition T(m) (differential scanning calorimetry) and membrane fluidity (DPH fluorescence polarization). Cells cultured and measured at 40 degrees C displayed the same membrane fluidity in all three media despite a markedly different fatty acid composition. The T(m) was surprisingly the highest in the case of a culture grown in complex medium. On the contrary, cultivation at 20 degrees C in the complex medium gave rise to the highest membrane fluidity with concomitant decrease of T(m) by 10.5 degrees C. In mineral media at 20 degrees C the corresponding changes of T(m) were almost negligible. After a temperature shift from 40 to 20 degrees C, the cultures from all three media displayed the same adaptive induction of fatty acid desaturase despite their different membrane fluidity values immediately after cold shock.
- MeSH
- Bacillus subtilis růst a vývoj fyziologie MeSH
- diferenciální skenovací kalorimetrie MeSH
- fluidita membrány * MeSH
- fluorescenční polarizace MeSH
- fyziologická adaptace * MeSH
- kultivační média MeSH
- nízká teplota * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kultivační média MeSH
Intermittent exposures to cold (15 head out immersions into 14 degrees C water, for 1 h, within 3 weeks) induce physiological changes leading to the restriction of heat loss from the body, due to hypothermia and vasoconstriction. These adaptational changes may save more than 25% of energy during 1 hour cold test. Insulative adaptation due to increased amount of the subcutaneous fat is less prominent. Winter swimmers show similar mechanisms of cold adaptationn as humans adapted by intermittent cold exposures in the laboratory. Additionally, winter swimmers exert a greater capacity of nonshivering thermogenesis than nonadapted controls. Thus, adaptation of humans to cold involves hypothermic, metabolic and insulative mechanisms. Time courses of development of individual mechanisms of adaptation differ. Intermittent local cold exposures (20 immersions of legs into 12 degrees C water, for 45 min, within 4 weeks lower sympathetic tone and induce redistribution of cardiac output, in order to ensure preferential warming of central parts of the body. Basal metabolism and cold induced thermogenesis are increased, but the threshold for induction of cold thermogenesis is not influenced. In contrast to changes induced by repeated whole body immersions, these changes may not ensure greater resistance to the cold stress.
- MeSH
- fyziologická adaptace fyziologie MeSH
- lidé MeSH
- nízká teplota * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- přehledy MeSH
Bacillus subtilis, which grows under aerobic conditions, employs fatty acid desaturase (Des) to fluidize its membrane when subjected to temperature downshift. Des requires molecular oxygen for its activity, and its expression is regulated by DesK-DesR, a two-component system. Transcription of des is induced by the temperature downshift and is decreased when membrane fluidity is restored. B. subtilis is also capable of anaerobic growth by nitrate or nitrite respiration. We studied the mechanism of cold adaptation in B. subtilis under anaerobic conditions that were predicted to inhibit Des activity. We found that in anaerobiosis, in contrast to aerobic growth, the induction of des expression after temperature downshift (from 37 degrees C to 25 degrees C) was not downregulated. However, the transfer from anaerobic to aerobic conditions rapidly restored the downregulation. Under both aerobic and anaerobic conditions, the induction of des expression was substantially reduced by the addition of external fluidizing oleic acid and was fully dependent on the DesK-DesR two-component regulatory system. Fatty acid analysis proved that there was no desaturation after des induction under anaerobic conditions despite the presence of high levels of the des protein product, which was shown by immunoblot analysis. The cold adaptation of B. subtilis in anaerobiosis is therefore mediated exclusively by the increased anteiso/iso ratio of branched-chain fatty acids and not by the temporarily increased level of unsaturated fatty acids that is typical under aerobic conditions. The degrees of membrane fluidization, as measured by diphenylhexatriene fluorescence anisotropy, were found to be similar under both aerobic and anaerobic conditions.
- MeSH
- aerobióza MeSH
- anaerobióza MeSH
- Bacillus subtilis metabolismus fyziologie MeSH
- bakteriální proteiny biosyntéza MeSH
- buněčná membrána chemie MeSH
- desaturasy mastných kyselin biosyntéza MeSH
- fluidita membrány MeSH
- fyziologická adaptace * MeSH
- mastné kyseliny metabolismus MeSH
- nízká teplota * MeSH
- regulace genové exprese u bakterií * MeSH
- signální transdukce MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bakteriální proteiny MeSH
- desaturasy mastných kyselin MeSH
- mastné kyseliny MeSH
- Klíčová slova
- ADAPTATION, PHYSIOLOGICAL *, CHROMOSOMES *, EVOLUTION *, NEOPLASMS, EXPERIMENTAL *,
- MeSH
- aklimatizace * MeSH
- biologická evoluce * MeSH
- chromozomy * MeSH
- experimentální nádory * MeSH
- fyziologická adaptace * MeSH
- nádory * MeSH
- Publikační typ
- časopisecké články MeSH
- Klíčová slova
- COLD *,
- MeSH
- aklimatizace * MeSH
- fyziologická adaptace * MeSH
- Hominidae * MeSH
- lidé MeSH
- nízká teplota * MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Repeated exposure to cold leads to a decline in the intensity of physiological defence reactions. In the complex of adaptational responses metabolic, thermogenic and insulation reactions predominate. The objective of the present investigation was to provide evidence of the predominating type of response of sportsmen exposed repeatedly to cold in an aqueous environment and to elucidate metabolic processes which serve to meet the energy demands of a certain type of adaptation to cold. METHODS AND RESULTS: The examination was made in a group of volunteers (men, mean age 21.0 +/- 1.8 years, height 1.80 +/- 0.04 m, body weight 77.0 +/- 3.1 kg, body fat 13.2 +/- 1.7%, anaerobic capacity expressed as maximum oxygen consumption 4.5 +/- 0.43 l.min-1). The cold acclimation programme involved immersion of the body into water 14 +/- 1 degree C 3 times a week for 1 month. During cold exposure the median body temperature before the acclimation programme dropped by 3.9 degrees C, after the acclimation programme by 4.1 degrees C. The total metabolic turnover after the programme declined by a 0.23 multiple of the metabolism at rest, at the end of the programme merely by a multiple of 0.07. During immersion the oxygen consumption doubled regardless of the stage of adaptation and an insignificant rise of non-esterified fatty acids occurred before the onset of the programme as well as after its termination. After the first exposure to cold a significant drop of the blood sugar was observed, while after the acclimation programme it increased insignificantly. The serum level of the thyroid stimulating hormone and triiodothyronine were affected only insignificantly by exposure to cold, the thyroxine level only at the borderline of significance before the onset of the acclimation programme. CONCLUSIONS: From values of the blood sugar level, respiratory quotient RQ, the non-esterified fatty acid level and body temperature at the periphery we may conclude that there is a restriction of the carbohydrate component as regards meeting energy demands of cold exposure before adaptation and a mixed type of meeting energy demands after termination of the cold acclimation programme.
- MeSH
- dospělí MeSH
- energetický metabolismus MeSH
- fyziologická adaptace fyziologie MeSH
- krevní glukóza analýza MeSH
- kyseliny mastné neesterifikované krev MeSH
- lidé MeSH
- nízká teplota * MeSH
- spotřeba kyslíku MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- Názvy látek
- krevní glukóza MeSH
- kyseliny mastné neesterifikované MeSH
A temperature shift-down of Bacillus subtilis from 40 to 20 degrees C induces an 80 min growth lag. Benzyl alcohol reduced this period to 51 min, whereas ethanol prolonged it up to 102 min. The effect of the two alcohols on the membrane state was investigated by measuring the steady-state fluorescence anisotropy and analysing the lifetime distribution of diphenylhexatriene (DPH) and its polar derivative, TMA-DPH. As followed from the fluorescence anisotropy, the two alcohols exerted similar (fluidizing) effects on the cytoplasmic membranes of B. subtilis. However, benzyl alcohol significantly shortened the main DPH lifetime component and widened its distribution, while ethanol had no effect. The benzyl alcohol activity was interpreted in terms of an increased membrane hydration due to disordering of the membrane structure. Such an effect imitates the cold shock induced synthesis of unsaturated fatty acids in B. subtilis. The fatty acid analysis revealed that ethanol hindered this adaptive synthesis of fatty acids. At the same time, its effect on the membrane state (membrane order) was very low and could not substitute the physiological response as was the case with benzyl alcohol. It can thus be concluded that the adaptation of the membrane physical state contributes significantly to the cold shock response of B. subtilis.
- MeSH
- anizotropie MeSH
- Bacillus subtilis účinky léků fyziologie ultrastruktura MeSH
- benzylalkohol farmakologie MeSH
- cytoplazma účinky léků metabolismus MeSH
- difenylhexatrien analogy a deriváty MeSH
- ethanol farmakologie MeSH
- fluorescenční barviva MeSH
- fyziologická adaptace účinky léků MeSH
- intracelulární membrány účinky léků metabolismus MeSH
- nenasycené mastné kyseliny metabolismus MeSH
- nízká teplota MeSH
- poločas MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Názvy látek
- 1-(4-(trimethylamino)phenyl)-6-phenylhexa-1,3,5-triene MeSH Prohlížeč
- benzylalkohol MeSH
- difenylhexatrien MeSH
- ethanol MeSH
- fluorescenční barviva MeSH
- nenasycené mastné kyseliny MeSH
