Heat strain and mortality effects of prolonged central European heat wave—an example of June 2019 in Poland

The occurrence of long-lasting severe heat stress, such as in July–August 2003, July 2010, or in April–May 2018 has been one of the biggest meteorological threats in Europe in recent years. The paper focuses on the biometeorological and mortality effects of the hot June that was observed in Central Europe in 2019. The basis of the study was hourly and daily Universal Thermal Climate Index (UTCI) values at meteorological stations in Poland for June 2019. The average monthly air temperature and UTCI values from 1951 to 2018 were analysed as background. Grosswetterlagen calendar of atmospheric circulation was used to assess synoptic conditions of heat wave. Several heat strain measures were applied : net heat storage (S), modelled heart rate (HR), sultriness (HSI), and UTCI index. Actual total mortality (TM) and modelled strong heat-related mortality (SHRM) were taken as indicators of biometeorological consequences of the hot June in 2019. The results indicate that prolonged persistence of unusually warm weather in June 2019 was determined by the synoptic conditions occurring over the European region and causing advection of tropical air. They led to the emergence of heat waves causing 10% increase in TM and 5 times bigger SHRM then in preceding 10 years. Such increase in SHRM was an effect of overheating and overload of circulatory system of human organism.

Wnt signaling related transcripts and their relationship to energy metabolism in C2C12 myoblasts under temperature stress

Temperature stress is one of the main environmental stressors affecting the welfare, health and productivity of livestock. Temperature changes can modify cell membrane components, disrupting the crosstalk between the cell and its surroundings by affecting signaling pathways including Wnt signaling pathway, which subsequently disrupts cell energy metabolism. The present study aims to understand the effect of temperature stress on the expression of genes involved in Wnt signaling pathways, and their interaction with energy metabolism in C2C12 myoblasts cells. The C2C12 cells were exposed to cold stress (35 °C), mild heat stress (39 °C) and severe heat stress (41 °C), whereas 37 °C was used as control temperature. Transcript levels of important genes involved in Wnt signaling including Axin2, Tnks2, Sfrp1, Dkk1, Dact1, Cby1, Wnt5a, Wnt7a, Wnt11, Porcn, Ror2, Daam1, and Ppp3ca were significantly altered under severe heat stress (41 °C), whereas eight Wnt signaling-related transcripts (Daam1, Ppp3ca, Fzd7, Wnt5a, Porcn, Tnks2, Lrp6, and Aes) were significantly altered under cold stress (35 °C) compared to control. Under heat stress transcripts of the Wnt/β-catenin inhibitors (Sfrp1, Dkk1, and Cby1) and negative regulators (Dact1 and Axin2) are activated. A positive correlation between oxidative phosphorylation and Wnt-related transcripts was found under high temperatures. Transcripts of the cell membrane receptors, including Lrp6 and Fzd7, and the members of Wnt/Ca+2 signaling pathway, including Ppp3ca and Porcn were downregulated under cold stress. Many Wnt signaling-related transcripts were positively correlated with glycolysis under cold stress. These findings indicate a cross-talk between Wnt signaling and energy metabolism under thermal stress.

Resisting the Heat: Bacterial Disaggregases Rescue Cells From Devastating Protein Aggregation

Bacteria as unicellular organisms are most directly exposed to changes in environmental growth conditions like temperature increase. Severe heat stress causes massive protein misfolding and aggregation resulting in loss of essential proteins. To ensure survival and rapid growth resume during recovery periods bacteria are equipped with cellular disaggregases, which solubilize and reactivate aggregated proteins. These disaggregases are members of the Hsp100/AAA+ protein family, utilizing the energy derived from ATP hydrolysis to extract misfolded proteins from aggregates via a threading activity. Here, we describe the two best characterized bacterial Hsp100/AAA+ disaggregases, ClpB and ClpG, and compare their mechanisms and regulatory modes. The widespread ClpB disaggregase requires cooperation with an Hsp70 partner chaperone, which targets ClpB to protein aggregates. Furthermore, Hsp70 activates ClpB by shifting positions of regulatory ClpB M-domains from a repressed to a derepressed state. ClpB activity remains tightly controlled during the disaggregation process and high ClpB activity states are likely restricted to initial substrate engagement. The recently identified ClpG (ClpK) disaggregase functions autonomously and its activity is primarily controlled by substrate interaction. ClpG provides enhanced heat resistance to selected bacteria including pathogens by acting as a more powerful disaggregase. This disaggregase expansion reflects an adaption of bacteria to extreme temperatures experienced during thermal based sterilization procedures applied in food industry and medicine. Genes encoding for ClpG are transmissible by horizontal transfer, allowing for rapid spreading of extreme bacterial heat resistance and posing a threat to modern food production.

Arbuscular Mycorrhizal Inoculation Enhances Endurance to Severe Heat Stress in Three Horticultural Crops

Global climate change is increasing temperatures worldwide, which greatly affects all biological relationships. Plant and soil ecosystems are also suffering in this new scenario, especially in semi-arid areas where water resources are limited. Regarding agricultural crops, temperatures that increase dramatically negatively affect fruit production and quality, making it mandatory to find sustainable practices to cope with these new situations. Symbiotic microorganisms in general and arbuscular mycorrhizal fungi in particular have been revealed as promising methods of alleviating stress that are respectful of the environment and soil equilibrium. In this work, we demonstrate the suitability of an ultra-pure, in vitro-issued arbuscular mycorrhizal inoculant for alleviating severe heat stress when applied to three important agricultural crops (tomato: Solanum lycopersicum L.; pepper: Capiscum annuum L.; cucumber: Cucumis sativus L.) under agronomic conditions. Inoculated plants had greatly improved endurance under heat stress because of increased vigor, productivity, and fruit quality. Considering the actual scenario of global climate change, our results shed a light of hope and indicate more sustainable cultivation practices adapted to global change.

Severe Heat Stress Resulted in High Coral Mortality on Maldivian Reefs following the 2015–2016 El Niño Event

Coral cover worldwide has been declining due to heat stress caused by climate change. Here we report the impacts of the 2015–2016 El Niño mass coral bleaching event on the coral cover of reefs located on central and northern atolls of the Maldives. We surveyed six reef sites in the Alifu Alifu (Ari) and Baa (South Maalhosmadulu) Atolls using replicate 20 m benthic photo transects at two depths per reef site. Live and recently dead coral cover identified from images differed between reef sites and depth. Recently dead corals on average made up 33% of the coral assemblage at shallow sites and 24% at deep sites. This mortality was significantly lower in massive corals than in branching corals, reaching an average of only 6% compared to 41%, respectively. The best predictors of live coral cover were depth and morphology, with a greater percentage of live coral at deep sites and in massive corals. The same predictors best described the prevalence of recently dead coral, but showed inverse trends to live coral. However, there was high variability among reef sites, which could be attributed to additional local stressors. Coral bleaching and resulting coral mortalities, such as the ones reported here, are of particular concern for small island nations like the Maldives, which are reliant on coral reefs.

Characterization of Two Small Heat Shock Protein Genes (Hsp17.4 and Hs20.3) from Sitodiplosis mosellana, and Their Expression Regulation during Diapause

Sitodiplosis mosellana, a periodic but devastating wheat pest that escapes temperature extremes in summer and winter by undergoing obligatory diapause. To determine the roles of small heat shock proteins (sHsps) in diapause of S. mosellana, we characterized two sHsp genes, SmHsp17.4 and SmHsp20.3, from this species. Both SmHsps contained the conserved α-crystallin domain and the carboxy-terminal I/VXI/V motif of the sHsp family. SmHsp17.4 had one intron while SmHsp20.3 had none. Quantitative PCR revealed that SmHsp17.4 expression decreased after diapause initiation, but substantially increased during transition to post-diapause quiescence. In contrast, SmHsp20.3 expression was not affected by entry of diapause, but was clearly up-regulated during summer and winter. Short-term more severe heat-stress (≥35 °C) of over-summering larvae or cold-stress (≤−5 °C) of over-wintering larvae could stimulate higher expression of both genes, and SmHsp17.4 was more responsive to cold stress while SmHsp20.3 was more sensitive to heat stress. Notably, transcription of SmHsp17.4, but not SmHsp20.3, in diapausing larvae was inducible by 20-hydroxyecdysone (20E). Recombinant SmHsp17.4 and SmHsp20.3 proteins also displayed significant chaperone functionality. These findings suggest that both SmHsps play key roles in stress tolerance during diapause; and 20E-regulated SmHsp17.4 was also likely involved in diapause termination.

The results of morphological examination of blood of cows under heat stress depending on the stages of temperature-humidity index

The results of morphological studies of the blood of cows under heat stress indicate that the temperature - humidity index (THI) of animals in comfortable conditions (THI - 68-71) the number of erythrocytes is 5.78 ± 0.13 T / l, the hematocrit - 24.98 ± 1.02%, hemoglobin content - 89.96 ± 2.63 g / l, MCV - 39.76 ± 2.31 fl; MCH - 15.56 ± 1.32 pg; MCHC - 39.14 ± 1.95 g / dl. The total number of leukocytes in the blood of cows is 7.17 ± 0.54 G / l. The relative content (leukogram) and the absolute number of certain types of leukocytes in the blood of cows has no abnormalities. This suggests that the morphological parameters of the blood of cows in the comfortable conditions of THI meet the normative values for cattle and, in particular, Holstein breed. Under moderate heat stress (THI -72-78), in the blood of cows, along with a significant increase in respiratory rate and heart rate, there is a tendency to increase the number of erythrocytes to 5.82 ± 0.69 T / l, there is a significant increase in hematocrit and MCV by 20 and 47%, and a significant decrease in hemoglobin, MCH and MCHC - by 32, 35 and 55%, respectively, relative to control. However, in the blood of cows there is a tendency to decrease the number of leukocytes, with the simultaneous appearance of metamyelocytes, an increase in the number of eosinophils and rod neutrophils, and a significant decrease in the number of lymphocytes by 27% compared to control. Under severe heat stress (THI - 80-90), when the pulse in cows fluctuates between 88-140 beats per minute, and the respiratory rate is 82.0 ± 3.76 respiratory movements, the number of erythrocytes in the blood of cows tends to decrease and is 5.01 ± 0.91 T / l. The hematocrit value is 21% significantly (p≤0.05) less than in cows under moderate heat stress, and is almost the same as in cows under comfortable conditions. The content of hemoglobin in the blood of cows in this period is significantly lower by 28% (p≤0.05) compared to that in cows under comfortable conditions with a slight tendency to increase compared to this figure in cows under moderate heat stress. Color indices indicate that in the blood of cows under severe heat stress there is a large number of young erythrocytes-macrocytes (MCV - 53.69 ± 3.22 fl), which are poor in hemoglobin (MSN - 12.95 ± 3.48 pg) and impaired hemoglobin formation (MCHC - 24.11 ± 2.23 g / dl). The total number of leukocytes in the blood of cows under severe heat stress is 10.80 ± 1.55 G / l, which is 78% (P≤0.01) more than under moderate heat stress and increases due to the appearance of young and an increase of almost in twice rod-shaped and segment-nuclear neutrophils and eosinophils with a simultaneous decrease in the percentage of lymphocytes.