scholarly journals Autophagy facilitates mitochondrial rebuilding after acute heat stress via a DRP-1–dependent process

2021 ◽  
Vol 220 (4) ◽  
Author(s):  
Yanfang Chen ◽  
Romane Leboutet ◽  
Céline Largeau ◽  
Siham Zentout ◽  
Christophe Lefebvre ◽  
...  
Keyword(s):  
Heat Stress ◽  
Mitochondrial Fission ◽  
Stress Conditions ◽  
Autophagic Flux ◽  
Mitochondrial Network ◽  
Major Site ◽  
Developmental Defects ◽  
Acute Heat Stress ◽  
The Matrix ◽  
Abnormal Mitochondria

Acute heat stress (aHS) can induce strong developmental defects in Caenorhabditis elegans larva but not lethality or sterility. This stress results in transitory fragmentation of mitochondria, formation of aggregates in the matrix, and decrease of mitochondrial respiration. Moreover, active autophagic flux associated with mitophagy events enables the rebuilding of the mitochondrial network and developmental recovery, showing that the autophagic response is protective. This adaptation to aHS does not require Pink1/Parkin or the mitophagy receptors DCT-1/NIX and FUNDC1. We also find that mitochondria are a major site for autophagosome biogenesis in the epidermis in both standard and heat stress conditions. In addition, we report that the depletion of the dynamin-related protein 1 (DRP-1) affects autophagic processes and the adaptation to aHS. In drp-1 animals, the abnormal mitochondria tend to modify their shape upon aHS but are unable to achieve fragmentation. Autophagy is induced, but autophagosomes are abnormally elongated and clustered on mitochondria. Our data support a role for DRP-1 in coordinating mitochondrial fission and autophagosome biogenesis in stress conditions.

Responses of broilers at moderate or high temperatures to dietary arginine:lysine ratio and source of supplemental methionine activity

2003 ◽  
Vol 54 (2) ◽  
pp. 177 ◽  
Author(s):  
J. Chen ◽  
J. Hayat ◽  
B. Huang ◽  
D. Balnave ◽  
J. Brake
Keyword(s):  
Heat Stress ◽  
High Temperatures ◽  
Feed Intake ◽  
Bodyweight Gain ◽  
Stress Conditions ◽  
Butanoic Acid ◽  
Acute Heat Stress

Recent studies have shown that the relative feed intake (FI) and bodyweight gain (BWG) responses of chronically heat-stressed broilers to equimolar additions of DL-methionine (DLM) or 2-hydroxy–4-(methylthio) butanoic acid (HMB; Alimet) can be altered by changing the arginine:lysine (arg:lys) ratio of the diet. However, no information is available concerning responses of broilers during acute heat stress. Broilers were exposed to either 22�C or 30�C during 3 consecutive 5-day experimental periods between 28 and 43 days of age. Responses to equimolar additions of the 2 sources of supplemental methionine activity were similar during exposure to 22�C at 28–33 days and 38–43 days of age. However, between 33 and 38 days of age, when the temperature was 30�C, increasing the dietary arg:lys ratio from 1.04 to 1.35 significantly improved the FI and BWG of broilers fed HMB, but not DLM. At an arg:lys ratio of 1.35, the BW gain of broilers fed HMB was significantly greater than that of broilers fed DLM. Therefore, under acute heat stress conditions the choice of a supplemental source of methionine activity should be dependent upon the dietary arg:lys ratio.

Abstract 222: Sigmar1 Mediates Mitochondrial Autophagy and Protects the Heart Against Ischemia/Reperfusion Injury

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Md. Shenuarin Bhuiyan ◽  
Shafiul Alam ◽  
Jonette M. Green ◽  
A. Wayne Orr ◽  
Jeanne James ◽  
...  
Keyword(s):  
Stress Response ◽  
Membrane Protein ◽  
Outer Membrane Protein ◽  
Cardiac Remodeling ◽  
Ischemia Reperfusion ◽  
Mitochondrial Fission ◽  
Mitochondrial Outer Membrane ◽  
Autophagic Flux ◽  
Autophagosome Formation ◽  
Abnormal Mitochondria

Rationale: Sigma 1 receptor (Sigmar1) is a highly expressed mitochondrion-associated ER membrane resident protein in different cell lines. We recently reported that Sigmar1 is highly expressed in cardiomyocytes but it’s molecular functions and role in the stress response still remains unknown. Objective: We investigated the functional role of Sigmar1 in mediating mitochondrial autophagy, mitochondrial fission and effects on stress resistance in the heart. Methods and Results: Subcellular fractionation and biochemical experiments confirmed Sigmar1 expression in the mitochondria, where it resides as an integral mitochondrial outer membrane protein. Sigmar1 overexpression induced mitochondrial fission, increased autophagosome formation and autophagic flux in cardiomyocytes. Similarly, cardiac specific Sigmar1 transgenic (Tg) mice showed increased levels of mitochondrial fission and mitochondrial autophagy without adverse effects. Conversely, Sigmar1 knockdown induced both mitochondrial elongation and accumulation of damaged mitochondria, whereas autophagosome formation and autophagic flux were reduced at baseline and in response to glucose deprivation in cardiomyocytes. Parallel studies using Sigmar1 knockout mice showed increased accumulation of abnormal mitochondria and significantly altered cardiac contractility. To define the functional significance of Sigmar1 in the cardiac stress response, we subjected the mice to ischemia/reperfusion (I/R) injury. Sigmar1 Tg mouse showed reduced infarct size, protected from I/R-injury induced adverse cardiac remodeling, and improved cardiac function associated with enhanced mitochondrial autophagy even 12 weeks after reperfusion injury. In contrary, knockdown of Sigmar1 evoked mitochondrial dysfunction, accumulation of abnormal mitochondria, enhanced adverse cardiac remodeling, aggravated cardiac dysfunction and increased susceptibility to I/R-injury. Conclusions: Our findings suggested that Sigmar1 is an integral mitochondrial outer membrane protein dispensable for constitutive mitochondrial quality control in normal hearts. Sigmar1 regulates mitochondrial autophagy to protect the heart against I/R injury-induced cardiac remodeling and dysfunction.

Repeated thermal conditioning during the neonatal period affects behavioral and physiological responses to acute heat stress in chicks

2020 ◽  
Vol 94 ◽  
pp. 102759
Author(s):  
Yoshimitsu Ouchi ◽  
Hiroshi Tanizawa ◽  
Jun-ichi Shiraishi ◽  
John F. Cockrem ◽  
Vishwajit S. Chowdhury ◽  
...  
Keyword(s):  
Heat Stress ◽  
Neonatal Period ◽  
Physiological Responses ◽  
Acute Heat Stress

scholarly journals Exploring Morpho-Physiological Variation for Heat Stress Tolerance in Tomato

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 347
Author(s):  
Samikshya Bhattarai ◽  
Joshua Harvey ◽  
Desire Djidonou ◽  
Daniel Leskovar
Keyword(s):  
Heat Stress ◽  
Chlorophyll Fluorescence ◽  
Open Field ◽  
Electrolyte Leakage ◽  
Leaf Gas Exchange ◽  
Total Yield ◽  
Stress Conditions ◽  
Heat Injury ◽  
Injury Index ◽  
Heat Tolerant

Texas tomato production is vulnerable to extreme heat in the spring-summer cropping period, which is exacerbated by the lack of superior genetic materials that can perform well in such environments. There is a dire need for selecting superior varieties that can adapt to warm environments and exhibit high yield stability under heat stress conditions. This research aimed at identifying heat-tolerant varieties under heat-stress conditions in controlled and open-field environments and was carried out in three stages. For the first experiment, 43 varieties were screened based on yield responses in natural open-field environment. From those, 18 varieties were chosen and exposed to control (greenhouse: 26/20 °C) and constant heat-stress (growth-chamber: 34/24 °C) conditions for three months. Measurements were done for chlorophyll fluorescence, chlorophyll content (SPAD), plant height, stem diameter and heat injury index (HII). The last experiment was conducted in an open field with a pool of varieties selected from the first and second experiments. Leaf gas exchange, leaf temperature, chlorophyll fluorescence, SPAD value, electrolyte leakage, heat injury index and yield were assessed. From the combined studies, we concluded that heat-tolerant genotypes selected by using chlorophyll fluorescence and HII in controlled heat-stress conditions also exhibited heat-tolerance in open-field environments. Electrolyte leakage and HII best distinguished tomato varieties in open-field environments as plants with low electrolyte leakage and HII had higher total yield. 'Heat Master,' 'New Girl,' 'HM-1823,' 'Rally,' 'Valley Girl,' 'Celebrity,' and 'Tribeca' were identified as high heat-tolerant varieties. Through trait correlation analysis we provide a better understanding of which traits could be useful for screening and breeding other heat-tolerant tomato varieties.

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