1
|
Grosiak M, Koteja P, Hambly C, Speakman JR, Sadowska ET. Limits to sustained energy intake. XXXIV. Can the heat dissipation limit (HDL) theory explain reproductive aging? J Exp Biol 2024; 227:jeb246592. [PMID: 38264846 DOI: 10.1242/jeb.246592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 01/11/2024] [Indexed: 01/25/2024]
Abstract
According to the heat dissipation limit (HDL) theory, reproductive performance is limited by the capacity to dissipate excess heat. We tested the novel hypotheses that (1) the age-related decline in reproductive performance is due to an age-related decrease of heat dissipation capacity and (2) the limiting mechanism is more severe in animals with high metabolic rates. We used bank voles (Myodes glareolus) from lines selected for high swim-induced aerobic metabolic rate, which have also increased basal metabolic rate, and unselected control lines. Adult females from three age classes - young (4 months), middle-aged (9 months) and old (16 months) - were maintained at room temperature (20°C), and half of the lactating females were shaved to increase heat dissipation capacity. Old females from both selection lines had a decreased litter size, mass and growth rate. The peak-lactation average daily metabolic rate was higher in shaved than in unshaved mothers, and this difference was more profound among old than young and middle-aged voles (P=0.02). In females with large litters, milk production tended to be higher in shaved (least squares mean, LSM±s.e.: 73.0±4.74 kJ day-1) than in unshaved voles (61.8±4.78 kJ day-1; P=0.05), but there was no significan"t effect of fur removal on the growth rate [4.47±2.29 g (4 days-1); P=0.45]. The results provide mixed support of the HDL theory and no support for the hypotheses linking the differences in reproductive aging with either a deterioration in thermoregulatory capability or genetically based differences in metabolic rate.
Collapse
Affiliation(s)
- Marta Grosiak
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Krakow 30-387, Poland
| | - Paweł Koteja
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Krakow 30-387, Poland
| | - Catherine Hambly
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
| | - John R Speakman
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Edyta T Sadowska
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Krakow 30-387, Poland
| |
Collapse
|
2
|
Brzęk P. What do molecular laws of life mean for species: absolute restrictions or mere suggestions? J Exp Biol 2023; 226:jeb245849. [PMID: 37756603 DOI: 10.1242/jeb.245849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
Evolutionary biologists are interested in finding universal patterns of covariation between macroscopic and molecular traits. Knowledge of such laws of life can be essential for understanding the course of evolutionary processes. Molecular parameters are presumably close to fundamental limits set to all organisms by laws of physics and chemistry. Thus, laws of life that include such parameters are hypothesized to be similar at both wide interspecific levels of variation and narrower levels of intraspecific and intraindividual variation in different species. In this Commentary, I discuss examples where the significance or direction of such molecular laws of life can be compared at different levels of biological variation: (1) the membrane pacemaker theory of metabolism, (2) the correlation between variation in metabolic rate and mitochondrial efficiency and (3) the allometric scaling of metabolism. All three examples reveal that covariations within species or individuals that include molecular parameters do not always follow patterns observed between species. I conclude that limits set by molecular laws of life can be circumvented (at least to some degree) by changes in other traits, and thus, they usually do not impose strict limitations on minor within-species evolutionary changes (i.e. microevolution). I also briefly discuss some of the most promising perspectives for future studies on the universality of molecular laws of life.
Collapse
Affiliation(s)
- Paweł Brzęk
- Faculty of Biology, University of Białystok, Ciołkowskiego 1J, 15-245 Białystok, Poland
| |
Collapse
|
3
|
Gladyshev MI, Sushchik NN. Long-chain Omega-3 Polyunsaturated Fatty Acids in Natural Ecosystems and the Human Diet: Assumptions and Challenges. Biomolecules 2019; 9:biom9090485. [PMID: 31547473 PMCID: PMC6770104 DOI: 10.3390/biom9090485] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 08/28/2019] [Accepted: 09/07/2019] [Indexed: 01/05/2023] Open
Abstract
Over the past three decades, studies of essential biomolecules, long-chain polyunsaturated fatty acids of the omega-3 family (LC-PUFAs), namely eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA), have made considerable progress, resulting in several important assumptions. However, new data, which continue to appear, challenge these assumptions. Based on the current literature, an attempt is made to reconsider the following assumptions: 1. There are algal classes of high and low nutritive quality. 2. EPA and DHA decrease with increasing eutrophication in aquatic ecosystems. 3. Animals need EPA and DHA. 4. Fish are the main food source of EPA and DHA for humans. 5. Culinary treatment decreases EPA and DHA in products. As demonstrated, some of the above assumptions need to be substantially specified and changed.
Collapse
Affiliation(s)
- Michail I Gladyshev
- Institute of Biophysics of Siberian Branch of Russian Academy of Sciences, Akademgorodok, 50/50, Krasnoyarsk 660036, Russia.
- Siberian Federal University, Svobodny av. 79, Krasnoyarsk 660041, Russia.
| | - Nadezhda N Sushchik
- Institute of Biophysics of Siberian Branch of Russian Academy of Sciences, Akademgorodok, 50/50, Krasnoyarsk 660036, Russia.
- Siberian Federal University, Svobodny av. 79, Krasnoyarsk 660041, Russia.
| |
Collapse
|
4
|
Price ER, Sirsat TS, Sirsat SKG, Dzialowski EM. Sarcoplasmic reticulum Ca 2+-ATPase (SERCA) activity during the transition to endothermy in an altricial bird. ACTA ACUST UNITED AC 2019; 222:222/13/jeb201111. [PMID: 31253731 DOI: 10.1242/jeb.201111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 05/30/2019] [Indexed: 01/15/2023]
Abstract
Sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) is a transmembrane pump critical to muscle calcium cycling during contraction, and SERCA has also been proposed as the basis for a non-shivering thermogenesis mechanism in birds. Despite its potential importance to both shivering and non-shivering thermogenesis, the activity of this transporter has rarely been studied in altricial birds, and never during the developmental transition from ectothermy to endothermy. Here, we describe SERCA activity in the pectoralis muscle and heart ventricle of red-winged blackbird (Agelaius phoeniceus) nestlings, fledglings and adults. Additionally, using a diet manipulation, we tested the hypothesis that muscle SERCA activity is affected by dietary fatty acid composition, as has been shown in some previous studies. In blackbird hearts, SERCA activity increased throughout development and into adulthood, conspicuously jumping higher just prior to fledging. In pectoralis muscle, SERCA activity increased throughout the nestling period, but then declined after fledging, an effect we attribute to remodeling of the muscle from a primarily heat-generating organ to a primarily force-generating organ. SERCA activity of the pectoralis muscle was correlated with the proportion of linoleic acid in muscle phospholipids when including all ages in the control group. However, in diet-manipulated birds, there was no consistent relationship between SERCA activity and muscle membrane fatty acid composition at any tested age (5-9 days old). It is unclear whether SERCA might be affected by developmental changes in fatty acid composition at younger ages.
Collapse
Affiliation(s)
- Edwin R Price
- Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - Tushar S Sirsat
- Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - Sarah K G Sirsat
- Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - Edward M Dzialowski
- Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| |
Collapse
|
5
|
Price ER, Sirsat TS, Sirsat SKG, Curran T, Venables BJ, Dzialowski EM. The membrane pacemaker hypothesis: novel tests during the ontogeny of endothermy. J Exp Biol 2018; 221:jeb.174466. [DOI: 10.1242/jeb.174466] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 02/14/2018] [Indexed: 01/09/2023]
Abstract
The ‘membrane pacemaker’ hypothesis proposes a biochemical explanation for among-species variation in resting metabolism, based on the positive correlation between membrane docosahexaenoic acid (DHA) and metabolic rate. We tested this hypothesis using a novel model, altricial red-winged blackbird nestlings, predicting that the proportion of DHA in muscle and liver membranes should increase with the increasing metabolic rate of the nestling as it develops endothermy. We also used a dietary manipulation, supplementing the natural diet with fish oil (high DHA) or sunflower oil (high linoleic acid) to alter membrane composition and then assessed metabolic rate. In support of the membrane pacemaker hypothesis, DHA proportions increased in membranes from pectoralis muscle, muscle mitochondria, and liver during post-hatch development. By contrast, elevated dietary DHA had no effect on resting metabolic rate, despite causing significant changes to membrane lipid composition. During cold challenges, higher metabolic rates were achieved by birds that had lower DHA and higher linoleic acid in membrane phospholipids. Given the mixed support for this hypothesis, we conclude that correlations between membrane DHA and metabolic rate are likely spurious, and should be attributed to a still-unidentified confounding variable.
Collapse
Affiliation(s)
- Edwin R. Price
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
| | - Tushar S. Sirsat
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
- Current address: Department of Biology, State University of New York Potsdam, Potsdam NY 13676, USA
| | - Sarah K. G. Sirsat
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
- Current address: Department of Biology, State University of New York Potsdam, Potsdam NY 13676, USA
| | - Thomas Curran
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
| | - Barney J. Venables
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
| | - Edward M. Dzialowski
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
| |
Collapse
|
6
|
Stawski C, Koteja P, Sadowska ET. A Shift in the Thermoregulatory Curve as a Result of Selection for High Activity-Related Aerobic Metabolism. Front Physiol 2017; 8:1070. [PMID: 29326604 PMCID: PMC5741638 DOI: 10.3389/fphys.2017.01070] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 12/05/2017] [Indexed: 12/28/2022] Open
Abstract
According to the “aerobic capacity model,” endothermy in birds and mammals evolved as a result of natural selection favoring increased persistent locomotor activity, fuelled by aerobic metabolism. However, this also increased energy expenditure even during rest, with the lowest metabolic rates occurring in the thermoneutral zone (TNZ) and increasing at ambient temperatures (Ta) below and above this range, depicted by the thermoregulatory curve. In our experimental evolution system, four lines of bank voles (Myodes glareolus) have been selected for high swim-induced aerobic metabolism and four unselected lines have been maintained as a control. In addition to a 50% higher rate of oxygen consumption during swimming, the selected lines have also evolved a 7.3% higher mass-adjusted basal metabolic rate. Therefore, we asked whether voles from selected lines would also display a shift in the thermoregulatory curve and an increased body temperature (Tb) during exposure to high Ta. To test these hypotheses we measured the RMR and Tb of selected and control voles at Ta from 10 to 34°C. As expected, RMR within and around the TNZ was higher in selected lines. Further, the Tb of selected lines within the TNZ was greater than the Tb of control lines, particularly at the maximum measured Ta of 34°C, suggesting that selected voles are more prone to hyperthermia. Interestingly, our results revealed that while the slope of the thermoregulatory curve below the lower critical temperature (LCT) is significantly lower in the selected lines, the LCT (26.1°C) does not differ. Importantly, selected voles also evolved a higher maximum thermogenesis, but thermal conductance did not increase. As a consequence, the minimum tolerated temperature, calculated from an extrapolation of the thermoregulatory curve, is 8.4°C lower in selected (−28.6°C) than in control lines (−20.2°C). Thus, selection for high aerobic exercise performance, even though operating under thermally neutral conditions, has resulted in the evolution of increased cold tolerance, which, under natural conditions, could allow voles to inhabit colder environments. Further, the results of the current experiment support the assumptions of the aerobic capacity model of the evolution of endothermy.
Collapse
Affiliation(s)
- Clare Stawski
- Faculty of Biology and Earth Sciences, Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland.,Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Paweł Koteja
- Faculty of Biology and Earth Sciences, Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Edyta T Sadowska
- Faculty of Biology and Earth Sciences, Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| |
Collapse
|