A new conceptual model for the warm-water breakdown of the coral - algae endosymbiosis

2009 ◽  
Vol 60 (6) ◽  
pp. 483 ◽  
Author(s):  
Scott A. Wooldridge
Keyword(s):  
Climate Change ◽  
Coral Bleaching ◽  
Warming Trend ◽  
Warm Water ◽  
Bisphosphate Carboxylase ◽  
Co2 Partial Pressure ◽  
Cellular Processes ◽  
Cellular Events ◽  
Precise Understanding ◽  
Limiting Condition

The symbiosis between reef-building corals and their algae endosymbionts is sensitive to temperature stress, which makes coral reefs vulnerable to climate change. However, a precise understanding of the capacity for the symbiosis to adapt to climate change is currently restricted by the lack of coherent explanation for the set of cellular events leading to its warm-water breakdown (= coral bleaching). Here, a new coral bleaching model is proposed in which the triggering event is a disruption to the ‘dark’ photosynthetic reactions of the algae endosymbionts, primarily due to a limited availability of CO2 substrate around the Rubisco enzyme (ribulose-1,5-bisphosphate carboxylase). Paradoxically, this CO2-limiting condition may be enhanced by the modern increase in atmospheric CO2 partial pressure (pCO2). Importantly, the model delivers a new standpoint from which to explain: (i) upper thermal bleaching thresholds; and (ii) the mechanism underpinning endosymbiont shuffling. Overall, the model leaves little doubt as to the diminished stability and functioning (i.e. resilience) of the coral–algae endosymbiosis due to the rising pCO2 and warming trend in the upper ocean surface layer. It is concluded that whole-colony bleaching is the destructive endpoint to a suite of cellular processes that operate near continuously in modern symbiotic corals.

Predicting cold-water bleaching in corals: role of temperature, and potential integration of light exposure

2020 ◽  
Vol 642 ◽  
pp. 133-146
Author(s):  
PC González-Espinosa ◽  
SD Donner
Keyword(s):  
Coral Bleaching ◽  
Cold Water ◽  
Light Exposure ◽  
Light Attenuation ◽  
Florida Keys ◽  
Cold Temperature ◽  
Warm Water ◽  
Coral Tissue ◽  
Effect Of Temperature ◽  
Type I

Warm-water growth and survival of corals are constrained by a set of environmental conditions such as temperature, light, nutrient levels and salinity. Water temperatures of 1 to 2°C above the usual summer maximum can trigger a phenomenon known as coral bleaching, whereby disruption of the symbiosis between coral and dinoflagellate micro-algae, living within the coral tissue, reveals the white skeleton of coral. Anomalously cold water can also lead to coral bleaching but has been the subject of limited research. Although cold-water bleaching events are less common, they can produce similar impacts on coral reefs as warm-water events. In this study, we explored the effect of temperature and light on the likelihood of cold-water coral bleaching from 1998-2017 using available bleaching observations from the Eastern Tropical Pacific and the Florida Keys. Using satellite-derived sea surface temperature, photosynthetically available radiation and light attenuation data, cold temperature and light exposure metrics were developed and then tested against the bleaching observations using logistic regression. The results show that cold-water bleaching can be best predicted with an accumulated cold-temperature metric, i.e. ‘degree cooling weeks’, analogous to the heat stress metric ‘degree heating weeks’, with high accuracy (90%) and fewer Type I and Type II errors in comparison with other models. Although light, when also considered, improved prediction accuracy, we found that the most reliable framework for cold-water bleaching prediction may be based solely on cold-temperature exposure.

scholarly journals TSPO: kaleidoscopic 18-kDa amid biochemical pharmacology, control and targeting of mitochondria

2016 ◽  
Vol 473 (2) ◽  
pp. 107-121 ◽  
Author(s):  
Jemma Gatliff ◽  
Michelangelo Campanella
Keyword(s):  
Neurological Diseases ◽  
Anion Channel ◽  
Translocator Protein ◽  
Endocrine Regulation ◽  
Voltage Dependent Anion Channel ◽  
Steroid Synthesis ◽  
Cellular Processes ◽  
Cellular Events ◽  
Voltage Dependent

The 18-kDa translocator protein (TSPO) localizes in the outer mitochondrial membrane (OMM) of cells and is readily up-regulated under various pathological conditions such as cancer, inflammation, mechanical lesions and neurological diseases. Able to bind with high affinity synthetic and endogenous ligands, its core biochemical function resides in the translocation of cholesterol into the mitochondria influencing the subsequent steps of (neuro-)steroid synthesis and systemic endocrine regulation. Over the years, however, TSPO has also been linked to core cellular processes such as apoptosis and autophagy. It interacts and forms complexes with other mitochondrial proteins such as the voltage-dependent anion channel (VDAC) via which signalling and regulatory transduction of these core cellular events may be influenced. Despite nearly 40 years of study, the precise functional role of TSPO beyond cholesterol trafficking remains elusive even though the recent breakthroughs on its high-resolution crystal structure and contribution to quality-control signalling of mitochondria. All this along with a captivating pharmacological profile provides novel opportunities to investigate and understand the significance of this highly conserved protein as well as contribute the development of specific therapeutics as presented and discussed in the present review.

Changes in the Amplitude of the Temperature Annual Cycle in China and Their Implication for Climate Change Research

2011 ◽  
Vol 24 (20) ◽  
pp. 5292-5302 ◽  
Author(s):  
Cheng Qian ◽  
Congbin Fu ◽  
Zhaohua Wu
Keyword(s):  
Climate Change ◽  
Annual Cycle ◽  
Linear Trend ◽  
Surface Air Temperature ◽  
Mean Amplitude ◽  
Warming Trend ◽  
Ensemble Empirical Mode Decomposition ◽  
Surface Solar Radiation ◽  
Climate Change Research ◽  
Annual Cycles

Abstract Climate change is not only reflected in the changes in annual means of climate variables but also in the changes in their annual cycles (seasonality), especially in the regions outside the tropics. In this study, the ensemble empirical mode decomposition (EEMD) method is applied to investigate the nonlinear trend in the amplitude of the annual cycle (which contributes 96% of the total variance) of China’s daily mean surface air temperature for the period 1961–2007. The results show that the variation and change in the amplitude are significant, with a peak-to-peak annual amplitude variation of 13% (1.8°C) of its mean amplitude and a significant linear decrease in amplitude by 4.6% (0.63°C) for this period. Also identified is a multidecadal change in amplitude from significant decreasing (−1.7% decade−1 or −0.23°C decade−1) to significant increasing (2.2% decade−1 or 0.29°C decade−1) occurring around 1993 that overlaps the systematic linear trend. This multidecadal change can be mainly attributed to the change in surface solar radiation, from dimming to brightening, rather than to a warming trend or an enhanced greenhouse effect. The study further proposes that the combined effect of the global dimming–brightening transition and a gradual increase in greenhouse warming has led to a perceived warming trend that is much larger in winter than in summer and to a perceived accelerated warming in the annual mean since the early 1990s in China. It also notes that the deseasonalization method (considering either the conventional repetitive climatological annual cycle or the time-varying annual cycle) can also affect trend estimation.

Climate Change Observations of Indigenous Communities in the Indian Himalaya

2021 ◽  
Vol 13 (2) ◽  
pp. 245-257
Author(s):  
Vikram S. Negi ◽  
Shinny Thakur ◽  
Rupesh Dhyani ◽  
Indra D. Bhatt ◽  
Ranbeer S. Rawal
Keyword(s):  
Climate Change ◽  
Climate Change Impacts ◽  
Indigenous Communities ◽  
Western Himalaya ◽  
Warming Trend ◽  
Indian Himalaya ◽  
Climate Anomalies ◽  
Change Perceptions ◽  
The Himalaya ◽  
Instrumental Temperature

AbstractMountains are important global sites for monitoring biological and socioecological responses to climate change, and the Himalaya has some of the world’s most rapid and visible signs of climate change. The increased frequency and severity of climate anomalies in the region are expected to significantly affect livelihoods of indigenous communities in the region. This study documents the perceptions of indigenous communities of climate change in the western Himalaya of India. The study highlights the power of knowledge and understanding available to indigenous people as they observe and respond to climate change impacts. We conducted a field-based study in 14 villages that represent diverse socioecological features along an altitudinal range of 1000–3800 m MSL in the western Himalaya. Among the sampled population, most of the respondents (>95%) agreed that climate is changing. However, people residing at low- and high-altitude villages differ significantly in their perception, with more people at high altitudes believing in an overall warming trend. Instrumental temperature and rainfall from nearby meteorological stations also supported the perception of local inhabitants. The climate change perceptions in the region were largely determined by sociodemographic variables such as age, gender, and income as well as altitude. A logistic regression, which exhibited significant association of sociodemographic characteristics with climate change perceptions, further supported these findings. The study concluded that the climate change observations of local communities can be usefully utilized to develop adaptation strategies and mitigation planning in the Himalayan region.

scholarly journals Calcium ionophore, A23187, induces commitment to differentiation but inhibits the subsequent expression of erythroid genes in murine erythroleukemia cells

Blood ◽  
1991 ◽  
Vol 77 (6) ◽  
pp. 1362-1370 ◽  
Author(s):  
JO Hensold ◽  
G Dubyak ◽  
DE Housman
Keyword(s):  
Transcriptional Activation ◽  
Calcium Ionophore ◽  
Erythroid Differentiation ◽  
Cytosolic Calcium ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Cellular Processes ◽  
Cellular Events ◽  
Erythroleukemia Cells ◽  
Murine Erythroleukemia

Abstract Murine erythroleukemia (MEL) cells are a useful model for studying the processes that regulate erythroid differentiation because exposure of these cells to a variety of chemical inducing agents results in expression of erythroid-specific genes and the resultant loss of cellular immortality. Previously it has been suggested that the calcium ionophore, A23187, has effects on the early cellular events that lead to the commitment of these cells to differentiation, but was not in itself sufficient to induce differentiation. We demonstrate here that A23187, as well as another calcium ionophore, ionomycin, are capable of inducing commitment to differentiation. Unlike other inducing agents, continual exposure to A23187 inhibits transcription of the erythroid- specific genes, beta-globin and Band 3. This effect is not attributable to an increase in cytosolic calcium concentration, because cells induced by ionomycin produce normal amounts of hemoglobin. These effects of A23187 on MEL cells confirm that commitment to differentiation is a distinct event from the subsequent transcriptional activation of erythroid genes. The ability of both ionophores to induce commitment to differentiation suggests that an increase in cytosolic calcium can trigger commitment to differentiation. These agents should prove useful in investigating the cellular processes that are responsible for commitment to differentiation.

scholarly journals A Roadmap for Intestinal Regeneration

2020 ◽  
Vol 52 ◽  
Author(s):  
David Quispe-Parra ◽  
Griselle Valentín ◽  
José E. García-Arrarás
Keyword(s):  
Molecular Mechanism ◽  
Sea Cucumber ◽  
Regenerative Process ◽  
Research Model ◽  
Functional Studies ◽  
Cellular Processes ◽  
Sequencing Technologies ◽  
Cellular Events ◽  
Intestinal Regeneration ◽  
Holothuria Glaberrima

Regeneration of lost or injured organs is an intriguing process where numerous cellular events take place to form the new structure. Studies of this process during reconstitution of the intestine have been performed in echinoderms, particularly in holothurians. Many cellular events triggered during regeneration have been described using the sea cucumber Holothuria glaberrima as a research model. More recent experiments have targeted the molecular mechanism behind the process, a task that has been eased by the new sequencing technologies now available. In this review we present the studies involving cellular processes and the genes that have been identified to be associated with the early events of gut regeneration. We also present the ongoing efforts to perform functional studies necessary to establish the role(s) of the identified genes. A synopsis of the studies is given with the course of the regenerative process established so far.

scholarly journals The Mixing Regime and Turbidity of Lake Banyoles (NE Spain): Response to Climate Change

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1621
Author(s):  
Teresa Serra ◽  
Josep Pascual ◽  
Ramon Brunet ◽  
Jordi Colomer
Keyword(s):  
Climate Change ◽  
Surface Waters ◽  
Warming Trend ◽  
Western Mediterranean ◽  
Aquifer Recharge ◽  
Temperature Changes ◽  
The Past ◽  
Deep Waters ◽  
Cooling Trend ◽  
Ne Iberian Peninsula

This study analyses the water temperature changes in Lake Banyoles over the past four decades. Lake Banyoles, Spain’s second highest lake, situated in the western Mediterranean (NE Iberian Peninsula). Over the past 44 years, the warming trend of the lake’s surface waters (0.52 °C decade−1) and the cooling trend of its deep waters (−0.66 °C decade−1) during summer (July–September) have resulted in an increased degree of stratification. Furthermore, the stratification period is currently double that of the 1970s. Meanwhile, over the past two decades, lake surface turbidity has remained constant in summer. Although turbidity did decrease during winter, it still remained higher than in the summer months. This reduction in turbidity is likely associated with the decrease in groundwater input into the lake, which has been caused by a significant decrease in rainfall in the aquifer recharge area that feeds the lake through groundwater sources. As a unique freshwater sentinel lake under the influence of the climate change, Lake Banyoles provides evidence that global warming in the western Mediterranean boosts the strength and duration of the lake’s stratification and, in response, the associated decrease in the turbidity of its epilimnion.

scholarly journals Attribution of the Australian bushfire risk to anthropogenic climate change

2020 ◽  
Author(s):  
Geert Jan van Oldenborgh ◽  
Folmer Krikken ◽  
Sophie Lewis ◽  
Nicholas J. Leach ◽  
Flavio Lehner ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Southern Annular Mode ◽  
Warming Trend ◽  
Anthropogenic Climate Change ◽  
Fire Season ◽  
Fire Weather ◽  
Weather Index ◽  
Fire Weather Index

Abstract. Disastrous bushfires during the last months of 2019 and January 2020 affected Australia, raising the question to what extent the risk of these fires was exacerbated by anthropogenic climate change. To answer the question for southeastern Australia, where fires were particularly severe, affecting people and ecosystems, we use a physically-based index of fire weather, the Fire Weather Index, long-term observations of heat and drought, and eleven large ensembles of state-of-the-art climate models. In agreement with previous analyses we find that heat extremes have become more likely by at least a factor two due to the long-term warming trend. However, current climate models overestimate variability and tend to underestimate the long-term trend in these extremes, so the true change in the likelihood of extreme heat could be larger. We do not find an attributable trend in either extreme annual drought or the driest month of the fire season September–February. The observations, however, show a weak drying trend in the annual mean. Finally, we find large trends in the Fire Weather Index in the ERA5 reanalysis, and a smaller but significant increase by at least 30 % in the models. The trend is mainly driven by the increase of temperature extremes and hence also likely underestimated. For the 2019/20 season more than half of the July–December drought was driven by record excursions of the Indian Ocean dipole and Southern Annular Mode. These factors are included in the analysis. The study reveals the complexity of the 2019/20 bushfire event, with some, but not all drivers showing an imprint of anthropogenic climate change.

Impact of Climate Change on Water Resources in the Shiyang River Basin and the Adaptive Measures for Energy Conservation and Emission Reduction

2013 ◽  
Vol 405-408 ◽  
pp. 2167-2171 ◽  
Author(s):  
Zhou Li ◽  
Xiao Yan Li ◽  
Juan Sun
Keyword(s):  
Climate Change ◽  
Surface Water ◽  
Water Resources ◽  
Energy Conservation ◽  
Climate Change Impacts ◽  
Warming Trend ◽  
Annual Runoff ◽  
Climate Scenarios ◽  
Surface Water Resources ◽  
Precipitation And Temperature

Climate is an important factor which formed and affected surface water resources. Through sensitivity analysis of natural runoff towards climate change, assuming the main factors effect runoff are precipitation and temperature, then according to the possible tendency of climate changes in the future, set climate scenarios, and use the hydrological model simulate the changes trend of runoff under different climate scenarios, thereby analyze the climate change impacts on surface water resources. The results show that annual runoff will be increased with the increasing annual precipitation, and it will be reduced with rise of annual temperature, the sensitivity that annual runoff towards the change of precipitation and temperature are equally notable, both of them are two major factors impact on the change of runoff and the precipitation change impacts on annual runoff will be even more obvious in flood season. Last, with the global warming trend, put forward the corresponding adaptive measures of energy conservation and emissions reduction。

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