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Sylvestre EL Lapointe D Dutil JD Guderley H 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2007,177(4):447-460
Atlantic cod populations live in a wide thermal range and can differ genetically and physiologically. Thermal sensitivity
of metabolic capacity and swimming performance may vary along a latitudinal gradient, to facilitate performance in distinct
thermal environments. To evaluate this hypothesis, we compared the thermal sensitivity of performance in two cod stocks from
the Northwest Atlantic that differ in their thermal experience: Gulf of St Lawrence (GSL) and Bay of Fundy (BF). We first
compared the metabolic, physiological and swimming performance after short-term thermal change to that at the acclimation
temperature (7°C) for one stock (GSL), before comparing the performance of the two stocks after short-term thermal change.
For cod from GSL, standard metabolism (SMR) increased with temperature, while active metabolism (AMR, measured in the critical
swimming tests), EMR (metabolic rate after an exhaustive chase protocol), aerobic scope (AS) and critical swimming speeds
(U
crit and U
b–c) were lower at 3°C than 7 or 11°C. In contrast, anaerobic swimming (sprint and burst-coasts in U
crit test) was lower at 11 than 7 or 3°C. Factorial AS (AMR SMR−1) decreased as temperature rose. Time to exhaustion (chase protocol) was not influenced by temperature. The two stocks differed
little in the thermal sensitivities of metabolism or swimming. GSL cod had a higher SMR than BF cod despite similar AMR and
AS. This led factorial AS to be significantly higher for the southern stock. Despite these metabolic differences, cod from
the two stocks did not differ in their U
crit speeds. BF cod were better sprinters at both temperatures. Cod from GSL had a lower aerobic cost of swimming at intermediate
speeds than those from BF, particularly at low temperature. Only the activity of cytochrome C oxidase (CCO) in white muscle
differed between stocks. No enzymatic correlates were found for swimming capacities, but oxygen consumption was best correlated
with CCO activity in the ventricle for both stocks. Overall, the stocks differed in their cost of maintenance, cost of transport
and sprint capacity, while maintaining comparable thermal sensitivities. 相似文献
2.
Exocytotic insertion of TRPC6 channel into the plasma membrane upon Gq protein-coupled receptor activation 总被引:10,自引:0,他引:10
Cayouette S Lussier MP Mathieu EL Bousquet SM Boulay G 《The Journal of biological chemistry》2004,279(8):7241-7246
TRPC proteins are the mammalian homologues of the Drosophila transient receptor potential channel and are involved in calcium entry after agonist stimulation of non-excitable cells. Seven mammalian TRPCs have been cloned, and their mechanisms of activation and regulation are still the subject of intense research. TRPC proteins interact with the inositol 1,4,5-trisphosphate receptor, and the conformational coupling plays a critical role in the activation of calcium entry. Some evidence also supports an exocytotic mechanism as part of the activation of calcium entry. To investigate the possible involvement of exocytosis in TRPC6 activation, we evaluated the location of TRPC6 at the plasma membrane by biotinylation labeling of cell surface proteins and by indirect immunofluorescence marking of TRPC6 in stably transfected HEK 293 cells. We showed that when the muscarinic receptor was stimulated or the thapsigargin-induced intracellular calcium pool was depleted the level of TRPC6 at the plasma membrane increased. The carbachol concentration at which TRPC6 externalization occurred was lower than the concentration required to activate TRPC6. Externalization occurred within the first 30 s of stimulation, and TRPC6 remained at the plasma membrane as long as the stimulus was present. These results indicate that an exocytotic mechanism is involved in the activation of TRPC6. 相似文献
3.
Auld Daniel S. Colomar Aurore Bélair Eve-Lyne Castonguay Annie Pinard Audrée Rousse Isabelle Thomas Sébastien Robitaille Richard 《Brain Cell Biology》2003,32(5-8):1003-1015
Perisynaptic Schwann cells are glial cells that are closely associated with pre- and postsynaptic elements of the neuromuscular junction. Recent evidence shows that these cells detect and modulate neurotransmission in an activity-dependent fashion. Through G-protein signalling and Ca2+ released from internal stores they can decrease or increase neurotransmitter release, respectively. Thus, they help to establish the level of neurotransmission associated with activity dependent short-term synaptic plasticity. We discuss evidence implicating perisynaptic Schwann cells as being active partners in neurotransmission at the neuromuscular junction, with emphasis on the modulation of short-term plasticity and potential implications for long-term changes. 相似文献
4.
Meier K Mathieu EL Finkernagel F Reuter LM Scharfe M Doehlemann G Jarek M Brehm A 《PLoS genetics》2012,8(5):e1002676
Mutations in the l(3)mbt tumour suppressor result in overproliferation of Drosophila larval brains. Recently, the derepression of different gene classes in l(3)mbt mutants was shown to be causal for transformation. However, the molecular mechanisms of dL(3)mbt-mediated gene repression are not understood. Here, we identify LINT, the major dL(3)mbt complex of Drosophila. LINT has three core subunits-dL(3)mbt, dCoREST, and dLint-1-and is expressed in cell lines, embryos, and larval brain. Using genome-wide ChIP-Seq analysis, we show that dLint-1 binds close to the TSS of tumour-relevant target genes. Depletion of the LINT core subunits results in derepression of these genes. By contrast, histone deacetylase, histone methylase, and histone demethylase activities are not required to maintain repression. Our results support a direct role of LINT in the repression of brain tumour-relevant target genes by restricting promoter access. 相似文献
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