scholarly journals Is there a role for sarcolipin in avian facultative thermogenesis in extreme cold?

2020 ◽  
Vol 16 (6) ◽  
pp. 20200078
Author(s):  
Maria Stager ◽  
Zachary A. Cheviron
Keyword(s):  
Gene Expression ◽  
Endoplasmic Reticulum ◽  
Oxygen Consumption ◽  
Heat Generation ◽  
Atp Hydrolysis ◽  
Transcript Abundance ◽  
Peak Oxygen Consumption ◽  
Gene Coding ◽  
Extreme Cold ◽  
Shivering Thermogenesis

Endotherms defend their body temperature in the cold by employing shivering (ST) and/or non-shivering thermogenesis (NST). Although NST is well documented in mammals, its importance to avian heat generation is unclear. Recent work points to a prominent role for the sarco/endoplasmic reticulum Ca 2+ ATPase (SERCA) in muscular NST. SERCA's involvement in both ST and NST, however, posits a tradeoff between these two heat-generating mechanisms. To explore this tradeoff, we assayed pectoralis gene expression of adult songbirds exposed to chronic temperature acclimations. Counter to mammal models, we found that cold-acclimated birds downregulated the expression of sarcolipin ( SLN ), a gene coding for a peptide that promotes heat generation by uncoupling SERCA Ca 2+ transport from ATP hydrolysis, indicating a reduced potential for muscular NST. We also found differential expression of many genes involved in Ca 2+ cycling and muscle contraction and propose that decreased SLN could promote increased pectoralis contractility for ST. Moreover, SLN transcript abundance negatively correlated with peak oxygen consumption under cold exposure (a proxy for ST) across individuals, and higher SLN transcript abundance escalated an individual's risk of hypothermia in acute cold. Our results therefore suggest that SLN-mediated NST may not be an important mechanism of—and could be a hindrance to—avian thermoregulation in extreme cold.

scholarly journals Patterns of thaumarchaeal gene expression in culture and diverse marine environments

2017 ◽  
Author(s):  
Paul Carini ◽  
Christopher L. Dupont ◽  
Alyson E. Santoro
Keyword(s):  
Gene Expression ◽  
Metabolic Regulation ◽  
Ammonia Oxidation ◽  
Expression Patterns ◽  
Transcriptional Response ◽  
Transcript Abundance ◽  
Ammonium Transporter ◽  
Growth State ◽  
Marine Habitats ◽  
Gene Coding

AbstractThaumarchaea are ubiquitous in marine habitats where they participate in carbon and nitrogen cycling. Although metatranscriptomes suggest thaumarchaea are active microbes in marine waters, we understand little about how thaumarchaeal gene expression patterns relate to substrate utilization and activity. Here, we report the global transcriptional response of the marine ammonia-oxidizing thaumarchaeon ‘CandidatusNitrosopelagicus brevis’ str. CN25 to ammonia limitation using RNA-Seq. We further describe the genome and transcriptome ofCa. N. brevis str. U25, a new strain capable of urea utilization. Ammonia limitation in CN25 resulted in reduced expression of transcripts coding for ammonia oxidation proteins, and increased expression of a gene coding an Hsp20-like chaperone. Despite significantly different transcript abundances across treatments, two ammonia monooxygenase subunits (amoAB), a nitrite reductase (nirK), and both ammonium transporter genes were always among the most abundant transcripts, regardless of growth state.Ca. N. brevis str. U25 cells expressed a urea transporter 139-fold more than the urease catalytic subunitureC. Gene co-expression networks derived from culture transcriptomes and ten thaumarchaea-enriched metatranscriptomes revealed a high degree of correlated gene expression across disparate environmental conditions and identified a module of genes, includingamoABCandnirK, that we hypothesize to represent the core ammonia oxidation machinery.Originality-Significance StatementDiscovering gene function in fastidious or uncultivated lineages remains one of the biggest challenges in environmental microbiology. Here, we use an approach that combines controlled laboratory experiments within situtranscript abundance data from the environment to identify genes that share similar transcription patterns in marine ammonia-oxidizing thaumarchaea. These findings demonstrate how transcriptomes from microbial cultures can be used together with complex environmental samples to identify suites of co-expressed genes that are otherwise enigmatic and provide new insights into the mechanism of ammonia oxidation. Our results add to the growing body of literature showing that relatively small changes in transcript abundance are linked to large changes in growth in organisms with reduced genomes, suggesting they have limited capacity for metabolic regulation or that they rely on mechanisms other than transcriptional regulation to deal with a fluctuating environment.

scholarly journals Effects of exercise on GLUT-4 and glycogenin gene expression in human skeletal muscle

2000 ◽  
Vol 88 (2) ◽  
pp. 794-796 ◽  
Author(s):  
Yorgos Kraniou ◽  
David Cameron-Smith ◽  
Marie Misso ◽  
Greg Collier ◽  
Mark Hargreaves
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Human Skeletal Muscle ◽  
Glycogen Synthesis ◽  
Cycle Ergometer ◽  
Peak Oxygen Consumption ◽  
Hexokinase Ii ◽  
Glut 4 ◽  
Single Bout

To investigate the effect of exercise on GLUT-4, hexokinase, and glycogenin gene expression in human skeletal muscle, 10 untrained subjects (6 women and 4 men, 21.4 ± 1.2 yr, 66.3 ± 5.0 kg, peak oxygen consumption = 2.30 ± 0.19 l/min) exercised for 60 min on a cycle ergometer at a power output requiring 73 ± 4% peak oxygen consumption. Muscle samples were obtained by needle biopsy before, immediately after, and 3 h after exercise. Gene expression was quantified, relative to 29S ribosomal protein cDNA, by RT-PCR. GLUT-4 gene expression was increased immediately after exercise (1.7 ± 0.4 vs. 0.9 ± 0.3 arbitrary units; P < 0.05) and remained significantly higher than baseline 3 h after the end of exercise (2.2 ± 0.4 vs. 0.9 ± 0.3 arbitrary units; P < 0.05). Hexokinase II gene expression was significantly higher than the resting value 3 h after the end of exercise (2.9 ± 0.4 vs. 1.3 ± 0.3 arbitrary units; P < 0.05). Exercise increased glycogenin mRNA more than twofold (2.8 ± 0.6 vs. 1.2 ± 0.2 arbitrary units; P < 0.05) 3 h after the end of exercise. For the first time, we report that a single bout of exercise is sufficient to cause upregulation of GLUT-4 and glycogenin gene expression in human skeletal muscle. Whether these increases, together with the associated increase in hexokinase II gene expression, lead to increased expression of these key proteins in skeletal muscle and contribute to the enhanced skeletal muscle glucose uptake, glycogen synthesis, and insulin action observed following exercise remains to be determined.

Unchanged [3H]ouabain binding site content but reduced Na+-K+ pump α2-protein abundance in skeletal muscle in older adults

2012 ◽  
Vol 113 (10) ◽  
pp. 1505-1511 ◽  
Author(s):  
Michael J. McKenna ◽  
Ben D. Perry ◽  
Fabio R. Serpiello ◽  
Marissa K. Caldow ◽  
Pazit Levinger ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Binding Site ◽  
Total Content ◽  
Peak Oxygen Consumption ◽  
Vastus Lateralis Muscle ◽  
Protein Abundance ◽  
Membrane Excitability ◽  
Ouabain Binding

Aging is associated with reduced muscle mass, weakness, and increased fatigability. In skeletal muscle, the Na+-K+ pump (NKA) is important in regulating Na+-K+ gradients, membrane excitability, and thus contractility, but the effects of aging on muscle NKA are unclear. We investigated whether aging is linked with reduced muscle NKA by contrasting muscle NKA isoform gene expression and protein abundance, and NKA total content in 17 Elderly (66.8 ± 6.4 yr, mean ± SD) and 16 Young adults (23.9 ± 2.2 yr). Participants underwent peak oxygen consumption assessment and a vastus lateralis muscle biopsy, which was analyzed for NKA α1-, α2-, α3-, β1-, β2-, and β3-isoform gene expression (real-time RT-PCR), protein abundance (immunoblotting), and NKA total content ([3H]ouabain binding sites). The Elderly had lower peak oxygen consumption (−36.7%, P = 0.000), strength (−36.3%, P = 0.001), NKA α2- (−24.4%, 11.9 ± 4.4 vs. 9.0 ± 2.7 arbitrary units, P = 0.049), and NKA β3-protein abundance (−23.0%, P = 0.041) than Young. The β3-mRNA was higher in Elderly compared with Young ( P = 0.011). No differences were observed between groups for other NKA isoform mRNA or protein abundance, or for [3H]ouabain binding site content. Thus skeletal muscle in elderly individuals was characterized by decreased NKA α2- and β3-protein abundance, but unchanged α1 abundance and [3H]ouabain binding. The latter was likely caused by reduced α2 abundance with aging, preventing an otherwise higher [3H]ouabain binding that might occur with a greater membrane density in smaller muscle fibers. Further study is required to verify reduced muscle NKA α2 with aging and possible contributions to impaired exercise capability and daily living activities.

Peak Oxygen Consumption and Resting Left Ventricular Ejection Fraction Changes After Cardiomyoplasty at 6-Month Follow-up

Circulation ◽  
1995 ◽  
Vol 92 (9) ◽  
pp. 216-222 ◽  
Author(s):  
Edimar Alcides Bocchi ◽  
Guilherme Veiga Guimarães ◽  
Luiz Felipe P. Moreira ◽  
Fernando Bacal ◽  
Alvaro Vilela de Moraes ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Left Ventricular Ejection Fraction ◽  
Ejection Fraction ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Peak Oxygen Consumption ◽  
Left Ventricular Ejection ◽  
Ventricular Ejection Fraction

scholarly journals Effects of face masks on performance and cardiorespiratory response in well-trained athletes

2021 ◽  
Author(s):  
Florian Egger ◽  
Dominic Blumenauer ◽  
Patrick Fischer ◽  
Andreas Venhorst ◽  
Saarraaken Kulenthiran ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Minute Ventilation ◽  
Anaerobic Exercise ◽  
Peak Oxygen Consumption ◽  
Exercise Tests ◽  
Maximum Performance ◽  
Outdoor Sports ◽  
Cardiorespiratory Response ◽  
Individual Anaerobic Threshold ◽  
The Individual

Abstract Background During the COVID-19 pandemic, compulsory masks became an integral part of outdoor sports such as jogging in crowded areas (e.g. city parks) as well as indoor sports in gyms and sports centers. This study, therefore, aimed to investigate the effects of medical face masks on performance and cardiorespiratory parameters in athletes. Methods In a randomized, cross-over design, 16 well-trained athletes (age 27 ± 7 years, peak oxygen consumption 56.2 ± 5.6 ml kg−1 min−1, maximum performance 5.1 ± 0.5 Watt kg−1) underwent three stepwise incremental exercise tests to exhaustion without mask (NM), with surgical mask (SM) and FFP2 mask (FFP2). Cardiorespiratory and metabolic responses were monitored by spiroergometry and blood lactate (BLa) testing throughout the tests. Results There was a large effect of masks on performance with a significant reduction of maximum performance with SM (355 ± 41 Watt) and FFP2 (364 ± 43 Watt) compared to NM (377 ± 40 Watt), respectively (p < 0.001; ηp2 = 0.50). A large interaction effect with a reduction of both oxygen consumption (p < 0.001; ηp2 = 0.34) and minute ventilation (p < 0.001; ηp2 = 0.39) was observed. At the termination of the test with SM 11 of 16 subjects reported acute dyspnea from the suction of the wet and deformed mask. No difference in performance was observed at the individual anaerobic threshold (p = 0.90). Conclusion Both SM and to a lesser extent FFP2 were associated with reduced maximum performance, minute ventilation, and oxygen consumption. For strenuous anaerobic exercise, an FFP2 mask may be preferred over an SM.

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