MOLECULAR AND EVOLUTIONARY BASIS OF THE CELLULAR STRESS RESPONSE

Transcriptomic response in thermally challenged seahorses Hippocampus erectus: The effect of magnitude and rate of temperature change

Hippocampus erectus inhabiting the shallow coastal waters of the southern Gulf of Mexico are naturally exposed to marked temperature variations occurring in different temporal scales. Under such heterogeneous conditions, a series of physiological and biochemical adjustments take place to restore and maintain homeostasis. This study investigated the molecular mechanisms involved in the response of H. erectus to increased temperature using transcriptome analysis based on RNA-Seq technology. Data was obtained from seahorses after 0.5-h exposure to combinations of different target temperatures (26 °C: control, and increased to 30 and 33 °C) and rates of thermal increase (abrupt: < 5 min; gradual: 1-1.5 °C every 3 h). The transcriptome of seahorses was assembled de novo using Trinity software to obtain 29,211 genes and 30,479 transcripts comprising 27,520,965 assembled bases. Seahorse exposure to both 30 and 33 °C triggered characteristic processes of the cellular stress response, regardless of the rate of thermal change. The transcriptomic profiles of H. erectus suggest an arrest of muscle development processes, the activation of heat shock proteins, and a switch to anaerobic metabolism within the first 0.5 h of exposure to target temperatures to ensure energy supply. Interestingly, apoptotic processes involving caspase were activated principally in gradual treatments, suggesting that prolonged exposure to even sublethal temperatures results in the accumulation of deleterious effects that may eventually terminate in cellular death. Results herein validate 30 °C and 33 °C as potential upper limits of thermal tolerance for H. erectus at the southernmost boundary of its geographic distribution.

Interactive effects of multiple stressors on the physiological performance of the invasive mussel Mytilus galloprovincialis

The invasive mussel Mytilus galloprovincialis is a heat-tolerant species relative to its competative congener M. trossulus, that dominates warm seawater environments but it is unknown how multiple stressors (MS) may affect its physiology. Our study determined the effects of MS on the metabolic rate (MR), superoxide dismutase (SOD) antioxidant enzyme activity, and clearance rate (CR) of M. galloprovincialis. Mussels were exposed for 7 d to hyposalinity (20, 28, 34 ppt) then to heat shock (17, 20, 25 °C) after which MR and SOD activity were determined. CR was quantified following a 30 min MS exposure. We found a significant influence of MS on MR, SOD, and CR. We identified synergistic effects on MR under the most extreme treatment. SOD activity was the greatest under 20 °C exposure while CR declined under heat shock. Thus, our study suggests that mussels experiencing MS may become energy limited as MR increases and feeding rates decrease.

Transcriptome profiles revealed high- and low-salinity water altered gill homeostasis in half-smooth tongue sole (Cynoglossus semilaevis)

Salinity is an important environmental factor that affects fish growth, development, and reproduction. As euryhaline fish, half-smooth tongue sole (Cynoglossus semilaevis) are a suitable species for deciphering the salinity adaptation mechanism of fish; however, the molecular mechanisms underlying low- and high-salinity responses remain unclear. In this study, RNA-seq was applied to characterize the genes and regulatory pathways involved in C. semilaevis gill responses to high- (32 ppt), low- (8 ppt), and control-salinity (24 ppt) water. Gills were rich in mitochondria-rich cells (MRCs) in high salinity. Compared with control, 2137 and 218 differentially expressed genes (DEGs) were identified in low and high salinity, respectively. The enriched functions of most DEGs were metabolism, ion transport, regulation of cell cycle, and immune response. The DEGs involved in oxidative phosphorylation, citrate cycle, and fatty acid metabolism were down-regulated in low salinity. For ion transport, high and low salinity significantly altered the expressions of prlr, ca12, and cftr. In cell cycle arrest and cellular repair, gadd45b, igfbp5, and igfbp2 were significantly upregulated in high and low salinity. For immune response, il10, il34, il12b, and crp increased in high and low salinity. Our findings suggested that alterations in material and energy metabolism, ions transport, cell cycle arrest, cellular repair, and immune response, are required to maintain C. semilaevis gill homeostasis under high and low salinity. This study provides insight into the divergence of C. semilaevis osmoregulation mechanisms acclimating to high and low salinity, which will serve as reference for the healthy culture of C. semilaevis.

Acute Nitrite Exposure Induces Dysfunction and Oxidative Damage in Grass Carp Isolated Hemocytes

To evaluate the effects of nitrite on the oxidative damage of blood cells of Grass Carp Ctenopharyngodon idella, the isolated hemocytes were exposed to nitrite (0, 1, 10, or 100 mg/L) for up to 24 h. Hemoglobin (Hb) and methemoglobin (MetHb) concentrations, reactive oxygen species (ROS) and malondialdehyde (MDA) levels, mitochondrial membrane potential (∆Ψm), and antioxidant enzyme activity were assayed to assess hematological parameters and the antioxidant defense mechanism. Results showed a remarkable decrease in Hb concentration with increasing nitrite concentration after a 24-h exposure, while the MetHb concentration increased significantly in nitrite exposure groups. The levels of ROS, ∆Ψm, and MDA increased to varying degrees with increases in nitrite exposure concentration and time. The total antioxidant capacity, catalase (CAT) activity, glutathione peroxidase (GPx) activity, and glutathione content showed a trend of rising initially and then decreasing with prolonged exposure time. Superoxide dismutase (SOD) activity was higher in the 1-mg/L nitrite exposure group and lower in the 100-mg/L group than in the control. The relative messenger RNA expression ratios of cat, sod1, and gpx were up-regulated significantly in the 1- and 10-mg/L groups and then declined in the 100-mg/L group. Therefore, it can be concluded that nitrite exposure activates the antioxidant defense mechanism of Grass Carp hemocytes and that the balance of oxidant-antioxidant homeostasis will be undermined by higher nitrite doses or longer exposure periods.

Does a Moderately Warming Climate Compensate for the Negative Effects of UV-B Radiation on Amphibians at High Altitudes? A Test of Rana kukunoris Living on the Qinghai–Tibetan Plateau

Simple Summary

Both the warming climate and ultraviolet-B radiation are notable environmental factors affecting tadpole development. However, the phenotypes of tadpoles living at high altitudes may be improved by moderately warming temperatures, reducing or eliminating the negative effects of oxidative damage caused by cool temperatures or strong ultraviolet-B radiation. To verify this hypothesis, Rana kukunoris tadpoles, which live at high altitudes, were exposed to ultraviolet-B radiation and ultraviolet-B radiation-free environments at 14 (cool temperature) and 22 °C (warm temperature), respectively. Ultraviolet-B radiation and a warm temperature had opposite influences on several traits of the tadpoles, and the moderate temperature could compensate for or override the negative effects of ultraviolet-B radiation by increasing the tadpoles’ preferred body temperature and critical tolerance temperature, thus enhancing the locomotion ability and thermal sensitivity of their antioxidant systems. The dark skin coloration and aggregation behavior of R. kukunoris tadpoles may also be effective strategies for allowing them to resist ultraviolet-B radiation and helping them to better adapt to a warming environment with stronger ultraviolet-B radiation. Thus, a moderate degree of warming may increase the capacity of living organisms to adapt to environmental changes and thus have positive effects on the development of tadpoles living at high altitudes.

Abstract

Both the warming climate and ultraviolet-B radiation (UVBR) are considered to be notable environmental factors affecting amphibian population decline, with particular effects on tadpole development. However, the phenotypes of tadpoles living at high altitudes may be improved by moderately warming temperatures, reducing or eliminating the negative effects of oxidative damage caused by cool temperatures or strong UVBR at high altitudes. To verify this hypothesis, Rana kukunoris tadpoles, which live at high altitudes, were used to test the effect of the interaction of temperature and UVBR on their development and antioxidant systems in a fully factorial design. The tadpoles were exposed to UVBR and UVBR-free environments at 14 (cool temperature) and 22 °C (warm temperature), respectively. UVBR and a warm temperature had opposite influences on several traits of the tadpoles, including their survival, developmental rate, individual size, preferred body temperature, thermal tolerance temperature, oxidative damage, and enzymatic and nonenzymatic antioxidant systems. The moderate temperature could compensate for or override the negative effects of UVBR by increasing the tadpoles’ preferred body temperature and critical tolerance temperature, thus enhancing the locomotion ability and thermal sensitivity of their antioxidant systems. Furthermore, the dark skin coloration and aggregation behavior of R. kukunoris tadpoles may also be effective strategies for allowing them to resist UVBR and helping them to better adapt to a warming environment with stronger UVBR. Thus, it is possible that a moderate degree of warming may increase the capacity of living organisms to adapt to environmental changes and thus have positive effects on the development of tadpoles living at high altitudes.

Prediction and Experimental Validation of a New Salinity-Responsive Cis-Regulatory Element (CRE) in a Tilapia Cell Line

Transcriptional regulation is a major mechanism by which organisms integrate gene x environment interactions. It can be achieved by coordinated interplay between cis-regulatory elements (CREs) and transcription factors (TFs). Euryhaline tilapia (Oreochromis mossambicus) tolerate a wide range of salinity and thus are an appropriate model to examine transcriptional regulatory mechanisms during salinity stress in fish. Quantitative proteomics in combination with the transcription inhibitor actinomycin D revealed 19 proteins that are transcriptionally upregulated by hyperosmolality in tilapia brain (OmB) cells. We searched the extended proximal promoter up to intron1 of each corresponding gene for common motifs using motif discovery tools. The top-ranked motif identified (STREME1) represents a binding site for the Forkhead box TF L1 (FoxL1). STREME1 function during hyperosmolality was experimentally validated by choosing two of the 19 genes, chloride intracellular channel 2 (clic2) and uridine phosphorylase 1 (upp1), that are enriched in STREME1 in their extended promoters. Transcriptional induction of these genes during hyperosmolality requires STREME1, as evidenced by motif mutagenesis. We conclude that STREME1 represents a new functional CRE that contributes to gene x environment interactions during salinity stress in tilapia. Moreover, our results indicate that FoxL1 family TFs are contribute to hyperosmotic induction of genes in euryhaline fish.

Metabolic Shades of S-D-Lactoylglutathione

S-D-lactoylglutathione (SDL) is an intermediate of the glutathione-dependent metabolism of methylglyoxal (MGO) by glyoxalases. MGO is an electrophilic compound that is inevitably produced in conjunction with glucose breakdown and is essentially metabolized via the glyoxalase route. In the last decades, MGO metabolism and its cytotoxic effects have been under active investigation, while almost nothing is known about SDL. This article seeks to fill the gap by presenting an overview of the chemistry, biochemistry, physiological role and clinical importance of SDL. The effects of intracellular SDL are investigated in three main directions: as a substrate for post-translational protein modifications, as a reservoir for mitochondrial reduced glutathione and as an energy currency. In essence, all three approaches point to one direction, namely, a metabolism-related regulatory role, enhancing the cellular defense against insults. It is also suggested that an increased plasma concentration of SDL or its metabolites may possibly serve as marker molecules in hemolytic states, particularly when the cause of hemolysis is a disturbance of the pay-off phase of the glycolytic chain. Finally, SDL could also represent a useful marker in such metabolic disorders as diabetes mellitus or ketotic states, in which its formation is expected to be enhanced. Despite the lack of clear-cut evidence underlying the clinical and experimental findings, the investigation of SDL metabolism is a promising field of research.

Transcriptomic and functional genetic evidence for distinct ecophysiological responses across complex life cycle stages

Organisms with complex life cycles demonstrate a remarkable ability to change their phenotypes across development, presumably as an evolutionary adaptation to developmentally variable environments. Developmental variation in environmentally sensitive performance, and thermal sensitivity in particular, has been well documented in holometabolous insects. For example, thermal performance in adults and juvenile stages exhibit little genetic correlation (genetic decoupling) and can evolve independently, resulting in divergent thermal responses. Yet, we understand very little about how this genetic decoupling occurs. We tested the hypothesis that genetic decoupling of thermal physiology is driven by fundamental differences in physiology between life stages, despite a potentially conserved Cellular Stress Response. We used RNAseq to compare transcript expression in response to a cold stressor in Drosophila melanogaster larvae and adults and used RNAi (RNA interference) to test whether knocking down nine target genes differentially affected larval and adult cold tolerance. Transcriptomic responses of whole larvae and adults during and following exposure to -5°C were largely unique both in identity of responding transcripts and in temporal dynamics. Further, we analyzed the tissue-specificity of differentially-expressed transcripts from FlyAtlas 2 data, and concluded that stage-specific differences in transcription were not simply driven by differences in tissue composition. In addition, RNAi of target genes resulted in largely stage-specific and sometimes sex-specific effects on cold tolerance. The combined evidence suggests that thermal physiology is largely stage-specific at the level of gene expression, and thus natural selection may be acting on different loci during the independent thermal adaptation of different life stages.

The Complex Interaction between P53 and miRNAs Joins New Awareness in Physiological Stress Responses

This review emphasizes the important role of cross-talk between P53 and microRNAs in physiological stress signaling. P53 responds to stress in a variety of ways ranging from activating survival-promotion pathways to triggering programmed cell death to eliminate damaged cells. In physiological stress generated by any external or internal condition that challenges cell homeostasis, P53 exerts its function as a transcription factor for target genes or by regulating the expression and maturation of a class of small non-coding RNA molecules (miRNAs). The miRNAs control the level of P53 through direct control of P53 or through indirect control of P53 by targeting its regulators (such as MDMs). In turn, P53 controls the expression level of miRNAs targeted by P53 through the regulation of their transcription or biogenesis. This elaborate regulatory scheme emphasizes the relevance of miRNAs in the P53 network and vice versa.

Dietary Sucrose Determines Stress Resistance, Oxidative Damages, and Antioxidant Defense System in Drosophila

Varied nutritional interventions affect lifespan and metabolic health. Abundant experimental evidence indicates that the carbohydrate restriction in the diet induces changes to support long-lived phenotypes. Reactive oxygen species (ROS) are among the main mechanisms that mediate the effect of nutrient consumption on the aging process. Here, we tested the influence of sucrose concentration in the diet on stress resistance, antioxidant defense systems, and oxidative stress markers in D. melanogaster. We found that high sucrose concentration in the fly medium leads to enhanced resistance to starvation, oxidative, heat, and cold stresses. However, flies that were raised on low sucrose food displayed increased levels of low-molecular-mass thiols, lipid peroxides in females, and higher activity of antioxidant enzymes, indicating that the consumption of a low carbohydrate diet could induce oxidative stress in the fruit fly. We found that the consumption of sucrose-enriched diet increased protein carbonyl level, which may indicate about the activation of glycation processes. The results highlight a strong dependence of oxidative metabolism in D. melanogaster from dietary carbohydrates.

Proteomic, biochemical, and anatomical influences of nanographene oxide on soybean (Glycine max)

Nano-graphene oxide (NGO) is an engineered nanostructure that is used in various fields including biology, chemistry, medicine, and environmental protection. This kind of highly used nanomaterial (NM) is being released and accumulated gradually in nature and can have some adverse influences on living organisms including plants. Soybean as a cultivated plant with a high importance in food industry, but sensitive to stresses, was chosen in the present study to be examined in terms of proteomic, biochemical, and anatomical properties under the NGO stress. Accordingly, a 2-dimensional gel electrophoresis (2-DE) approach was adopted for proteomic analysis of the NGO treated soybean roots, where significant changes were observed in the abundance of 48 proteins. MALDI TOF/TOF analysis revealed the upregulation of the proteins involved in the redox regulation in plants. Furthermore, anatomical examination of soybean roots under light microscopy showed that the NGO could enter into the root epidermis through the apoplastic pathway and accumulated in some parts of the root. With increasing NGO concentration, the diameter of the vascular apertures increased and then decreased at higher concentrations. To evaluate the toxicity of NGO, some of the growth parameters including fresh and dry weight, and height of the shoots, as well as some stress-related biochemical properties such as H2O2 production, antioxidant enzymes activity, and phenolics and flavonoids contents were measured. The results indicated that NGO could cause an oxidative stress, which can be considered a toxic effect evoking antioxidative and detoxification mechanisms in soybean.

Developmental toxicity of glyphosate on embryo-larval zebrafish (Danio rerio)

Glyphosate (GLY) induces developmental toxicity in fish, but research on the toxicity mechanism is limited. In this study, zebrafish embryos were exposed for 120 hpf to 0.7, 7, and 35 mg L-1 GLY. The results show that GLY treatment induced developmental toxicity in the fish, including premature hatching, reduced heartbeats, pericardial and yolk sac oedema, swim bladder deficiency, and shortened body length, which was possibly due to a significantly decreased triiodothyronine (T3)/thyroxine (T4) ratio and the abnormal expression patterns of hypothalamic-pituitary-thyroid (HPT) (crh, tshβ, tr α, tr β, and t tr ) and growth hormone/insulin-like growth factor (GH/IGF) axis-related genes (gh, ghrα, ghrβ, igf1, igf1rα, and igf1rβ) in larvae exposed to GLY. In addition, GLY exposure altered the levels of SOD and CAT, increased ROS, promoted malondialdehyde (MDA) content, and significantly altered the levels of endoplasmic reticulum (ER) stress signalling pathway factors (perk, eif2α, gadd34, atf4, ire1α, xbp1, atf6, hspa5, and chop), suggesting that GLY treatment induced oxidative injury and ER stress in the larvae. Further research showed that treatment with a higher concentration of GLY upregulated the levels of iNOS, IL-1β, and TNF-α while inhibiting the expression of IL-10 and TGF-β, suggesting that GLY causes an inflammatory reaction in the larvae. In addition, we also found that apoptosis was induced in the larvae, which was determined by acridine orange staining and abnormal expression of p53, caspase-3, -8, and -9. Taken together, our results demonstrate that GLY exposure altered the T3/T4 ratio, disturbed the expression patterns of HPT and GH/IGF axis-related genes, and induced oxidative and ER stress, inflammatory reactions, and apoptosis in the zebrafish larvae. This investigation contributes to improved understanding of the developmental toxicity mechanism of GLY in fish.

Predictability of thermal fluctuations influences functional traits of a cosmopolitan marine diatom

Evolutionary theory predicts that organismal plasticity should evolve in environments that fluctuate regularly. However, in environments that fluctuate less predictably, plasticity may be constrained because environmental cues become less reliable for expressing the optimum phenotype. Here, we examine how the predictability of +5°C temperature fluctuations impacts the phenotype of the marine diatom Thalassiosira pseudonana. Thermal regimes were informed by temperatures experienced by microbes in an ocean simulation and featured regular or irregular temporal sequences of fluctuations that induced mild physiological stress. Physiological traits (growth, cell size, complexity and pigmentation) were quantified at the individual cell level using flow cytometry. Changes in cellular complexity emerged as the first impact of predictability after only 8–11 days, followed by deleterious impacts on growth on days 13–16. Specifically, cells with a history of irregular fluctuation exposure exhibited a 50% reduction in growth compared with the stable reference environment, while growth was 3–18 times higher when fluctuations were regular. We observed no evidence of heat hardening (increasingly positive growth) with recurrent fluctuations. This study demonstrates that unpredictable temperature fluctuations impact this cosmopolitan diatom under ecologically relevant time frames, suggesting shifts in environmental stochasticity under a changing climate could have widespread consequences among ocean primary producers.

Environment-driven shifts in inter-individual variation and phenotypic integration within subnetworks of the mussel transcriptome and proteome

The environment can alter the magnitude of phenotypic variation among individuals, potentially influencing evolutionary trajectories. However, environmental influences on variation are complex and remain understudied. Populations in heterogeneous environments might exhibit more variation, the amount of variation could differ between benign and stressful conditions, and/or variation might manifest in different ways among stages of the gene‐to‐protein expression cascade or among physiological functions. Here, we explore these three issues by quantifying patterns of inter‐individual variation in both transcript and protein expression levels among California mussels, Mytilus californianus Conrad. Mussels were exposed to five ecologically relevant treatments that varied in the mean and interindividual heterogeneity of body temperature. To target a diverse set of physiological functions, we assessed variation within 19 expression subnetworks, including canonical stress‐response pathways and empirically derived coexpression clusters that represent a diffuse set of cellular processes. Variation in expression was particularly pronounced in the treatments with high mean and heterogeneous body temperatures. However, with few exceptions, environment‐dependent shifts of variation in the transcriptome were not reflected in the proteome. A metric of phenotypic integration provided evidence for a greater degree of constraint on relative expression levels (i.e., stronger correlation) within expression subnetworks in benign, homogeneous environments. Our results suggest that environments that are more stressful on average – and which also tend to be more heterogeneous – can relax these expression constraints and reduce phenotypic integration within biochemical subnetworks. Context‐dependent “unmasking” of functional variation may contribute to interindividual differences in physiological phenotype and performance in stressful environments.

ORA47 is a transcriptional regulator of a general stress response hub

Transcriptional regulators of the general stress response (GSR) reprogram the expression of selected genes to transduce informational signals into cellular events, ultimately manifested in a plant's ability to cope with environmental challenges. Identification of the core GSR regulatory proteins will uncover the principal modules and their mode of action in the establishment of adaptive responses. To define the GSR regulatory components, we employed a yeast-one-hybrid assay to identify the protein(s) binding to the previously established functional GSR motif, termed the rapid stress response element (RSRE). This led to the isolation of octadecanoid-responsive AP2/ERF-domain transcription factor 47 (ORA47), a methyl jasmonate inducible protein. Subsequently, ORA47 transcriptional activity was confirmed using the RSRE-driven luciferase (LUC) activity assay performed in the ORA47 loss- and gain-of-function lines introgressed into the 4xRSRE::Luc background. In addition, the prime contribution of CALMODULIN-BINDING TRANSCRIPTIONAL ACTIVATOR3 (CAMTA3) protein in the induction of RSRE was reaffirmed by genetic studies. Moreover, exogenous application of methyl jasmonate led to enhanced levels of ORA47 and CAMTA3 transcripts, as well as the induction of RSRE::LUC activity. Metabolic analyses illustrated the reciprocal functional inputs of ORA47 and CAMTA3 in increasing JA levels. Lastly, transient assays identified JASMONATE ZIM-domain1 (JAZ1) as a repressor of RSRE::LUC activity. Collectively, the present study provides fresh insight into the initial features of the mechanism that transduces informational signals into adaptive responses. This mechanism involves the functional interplay between the JA biosynthesis/signaling cascade and the transcriptional reprogramming that potentiates GSR. Furthermore, these findings offer a window into the role of intraorganellar communication in the establishment of adaptive responses.

Biomolecular alterations in the early life stages of four food fish following acute exposure of Triclosan

We investigated the effect of acute concentrations of triclosan (TCS; 96 h exposure and 10d post exposure) on the free amino acid, primary (SDS-PAGE) and secondary (FT-IR) structure of proteins in the embryos/larvae of Cyprinus carpio, Ctenopharyngodon idella, Labeo rohita and Cirrhinus mrigala. A concentration dependent increase in free amino acids, upregulation of polypeptides (100 and 70 kDa in C. carpio, C. idella and L. rohita, 55, 45, 36 kda in C. idella and L. rohita and 22 kDa in all the fish) and a decline in percent area of all the selected peaks of the FT-IR spectra was observed after exposure and recovery period. The decline in percent area was greatest for L. rohita at peak 1080 - 1088 cm^-1 (-75.99%) after exposure and at peak 2854 - 2855 cm^-1 (-53.59%) after recovery. Curve fitting analysis revealed a decrease in α-helices and increase in β-sheets in all fish after exposure and recovery period. The results suggest that TCS elicits alterations in biomolecules of fish embryos.

Temperature and salinity effects on whole-organism and cellular level stress responses of the sub-Antarctic notothenioid fish Patagonotothen cornucola yolk-sac larvae

This work aimed to evaluate the whole-organism and cellular level responses to different combinations of water temperature and salinity of the notothenioid Patagonotothen cornucola at the end of the yolk-sac larval stage. Egg masses of the species were collected in the wild and then maintained at natural water conditions (4 °C and 30 PSU). Newly hatched larvae were placed in aquaria with different combinations of water temperature (4 °C, 12 °C, and 16 °C) and salinity (15 and 30 PSU) during four days before yolk sac absorption. Larvae exposed to 12 °C grew more in length than those exposed to 16 °C, but yolk volume was more reduced in larvae exposed to 16 °C than those exposed to 4 °C and 30 PSU than of 15 PSU. In addition, a higher proportion of larvae exposed to 12 °C and 15 PSU completely absorbed their yolk. Whereas the more tolerant larvae to high temperatures were those exposed to 16 °C and 30 PSU, lipid peroxidation and protein oxidation were highest at natural and at 12 °C and 30 PSU conditions, respectively. The nutritional status (as standardized DNA/RNA index-sRD -) was low in all cases, even at natural conditions (average sRD ~ 1). Our study suggests that, in the context of climate change, the mortality rate of yolk-sac larvae of P. cornucola would not increase due to temperature or salinity stress. However, indirect effects (such as habitat degradation or changes in food availability) would be critical after complete absorption of the yolk.

Comparative Transcriptomics of the Northern Quahog Mercenaria mercenaria and Southern Quahog Mercenaria campechiensis in Response to Chronic Heat Stress

The northern quahog (Mercenaria mercenaria) supports lucrative aquaculture industries in the USA. In the southeastern USA, aquacultured M. mercenaria faces increasing risks of summer die-offs from prolonged heat waves. We used a comparative transcriptomic approach to investigate the molecular responses of M. mercenaria and its southern congener, Mercenaria campechiensis, to controlled incremental heat stress over a 4-week period. Mercenaria were exposed to temperatures from 24 to 34 °C with 2.5 °C/week, after which, gill transcriptomes were de novo assembled and annotated. During the 4 weeks of chronic heat exposure, both species had the same survival rate (96%); M. mercenaria experienced body weight gain/loss depending on the originated hatcheries while M. campechiensis experienced an average net weight loss. The upregulated genes in both species included those in chaperone-mediated protein folding and regulation of cell death pathways, while the downregulated genes in both species involved in mRNA processing and splicing pathways. Compared to M. mercenaria, M. campechiensis appears to be more sensitive to prolonged heat stress as indicated by upregulating significantly more genes in coping with oxidative stress and in the protein degradation pathways, while downregulating some inhibitors of apoptosis. We discussed this finding within their ecological and evolutionary context. Our findings highlighted the potential vulnerability of the two quahogs, especially the southern quahog, to continued ocean warming.

Molecular Mechanism Based on Histopathology, Antioxidant System and Transcriptomic Profiles in Heat Stress Response in the Gills of Japanese Flounder

As an economically important flatfish in Asia, Japanese flounder is threatened by continuously rising temperatures due to global warming. To understand the molecular responses of this species to temperature stress, adult Japanese flounder individuals were treated with two kinds of heat stress—a gradual temperature rise (GTR) and an abrupt temperature rise (ATR)—in aquaria under experimental conditions. Changes in histopathology, programmed cell death levels and the oxidative stress status of gills were investigated. Histopathology showed that the damage caused by ATR stress was more serious. TUNEL signals confirmed this result, showing more programmed cell death in the ATR group. In addition, reactive oxygen species (ROS) levels and the 8-O-hDG contents of both the GTR and ATR groups increased significantly, and the total superoxide dismutase (T-SOD) activities and total antioxidant capacity (T-AOC) levels decreased in the two stressed groups, which showed damage to antioxidant systems. Meanwhile, RNA-seq was utilized to illustrate the molecular mechanisms underyling gill damage. Compared to the control group of 18 °C, 507 differentially expressed genes (DEGs) were screened in the GTR group; 341 were up-regulated and 166 were down-regulated, and pathway enrichment analysis indicated that they were involved in regulation and adaptation, including chaperone and folding catalyst pathways, the mitogen-activated protein kinase signaling (MAPK) pathway and DNA replication protein pathways. After ATR stress, 1070 DEGs were identified, 627 were up-regulated and 423 were down-regulated, and most DEGs were involved in chaperone and folding catalyst and DNA-related pathways, such as DNA replication proteins and nucleotide excision repair. The annotation of DEGs showed the great importance of heat shock proteins (HSPs) in protecting Japanese flounder from heat stress injury; 12 hsp genes were found after GTR, while 5 hsp genes were found after ATR. In summary, our study records gill dysfunction after heat stress, with different response patterns observed in the two experimental designs; chaperones were activated to defend heat stress after GTR, while replication was almost abandoned due to the severe damage consequent on ATR stress.

Malaria parasites do respond to heat

The capacity of malaria parasites to respond to changes in their environment at the transcriptional level has been the subject of debate, but recent evidence has unambiguously demonstrated that Plasmodium spp. can produce adaptive transcriptional responses when exposed to some specific types of stress. These include metabolic conditions and febrile temperature. The Plasmodium falciparum protective response to thermal stress is similar to the response in other organisms, but it is regulated by a transcription factor evolutionarily unrelated to the conserved transcription factor that drives the heat shock (HS) response in most eukaryotes. Of the many genes that change expression during HS, only a subset constitutes an authentic response that contributes to parasite survival.

Physiological mechanisms of stress-induced evolution

Organisms mount the cellular stress response whenever environmental parameters exceed the range that is conducive to maintaining homeostasis. This response is critical for survival in emergency situations because it protects macromolecular integrity and, therefore, cell/organismal function. From an evolutionary perspective, the cellular stress response counteracts severe stress by accelerating adaptation via a process called stress-induced evolution. In this Review, we summarize five key physiological mechanisms of stress-induced evolution. Namely, these are stress-induced changes in: (1) mutation rates, (2) histone post-translational modifications, (3) DNA methylation, (4) chromoanagenesis and (5) transposable element activity. Through each of these mechanisms, organisms rapidly generate heritable phenotypes that may be adaptive, maladaptive or neutral in specific contexts. Regardless of their consequences to individual fitness, these mechanisms produce phenotypic variation at the population level. Because variation fuels natural selection, the physiological mechanisms of stress-induced evolution increase the likelihood that populations can avoid extirpation and instead adapt under the stress of new environmental conditions.

Mechanisms tailoring the expression of heat shock proteins to proteostasis challenges

All cells possess an internal stress response to cope with environmental and pathophysiological challenges. Upon stress, cells reprogram their molecular functions to activate a survival mechanism known as the heat shock response, which mediates the rapid induction of molecular chaperones such as the heat shock proteins (HSPs). This potent production overcomes the general suppression of gene expression and results in high levels of HSPs to subsequently refold or degrade misfolded proteins. Once the damage or stress is repaired or removed, cells terminate the production of HSPs and resume regular functions. Thus, fulfillment of the stress response requires swift and robust coordination between stress response activation and completion that is determined by the status of the cell. In recent years, single-cell fluorescence microscopy techniques have begun to be used in unravelling HSP-gene expression pathways, from DNA transcription to mRNA degradation. In this review, we will address the molecular mechanisms in different organisms and cell types that coordinate the expression of HSPs with signaling networks that act to reprogram gene transcription, mRNA translation, and decay and ensure protein quality control.

Extracellular circulating miRNAs as stress-related signature to search and rescue dogs

Our research explores serum extracellular circulating miRNAs (ecmiRNAs) involved in dog stress response immediately after the search and rescue (SAR) of missing people. The experimental plan considers four arduous SAR simulations. The SAR dogs are trained by the Alpine School of the Military Force of Guardia di Finanza (Passo Rolle, Italy). The First SAR Trial analyzed dog serum samples at rest time (T0), and immediately after SAR performance (T1) using the miRNome-wide screening next-generation sequencing (NGS). T1 versus T0 NGS results revealed a different expression level of let-7a and let-7f. Subsequently, in a large sample size including: 1st (n = 6), 2nd (n = 6), 3rd (n = 6), and 4th (n = 4) trials, let-7a and let-7f were validated by qPCR. Bioinformatics analysis with TarBase (v.8) and the Diana-mirPath (v.3) revealed a functional role of let-7a and let-7f in the p53 pathway to restore cellular homeostasis. Let-7a and let-7f, highly expressed at T1, could stop MDMs-p53 inhibition inducing the p53 increase in level. In addition, let-7a and let-7f, via p53 post-transcriptional regulation, buffers p53 transcription spikes. During SAR stress, the possibility of p53 preconditioning could explain the phenomenon of "stress hardening" where the tolerance of particular stress increases after preconditioning.

Collective Learnings of Studies of Stress Granule Assembly and Composition

Stress granules have gained considerable exposure and interest in recent years. These micron-sized entities, composed of RNA and protein, form following a stress exposure and have been linked to several pathologies. Understanding stress granule function is paramount but has been arduous due to the membraneless nature of these organelles. Several new methodologies have recently been developed to catalogue the protein and RNA composition of stress granules. Collectively, this work has provided important insights to potential stress granule functions as well as molecular mechanisms for their assembly and disassembly. This chapter reviews the latest advancements in the understanding of stress granule dynamics and discusses the various protocols developed to study their composition.

Alpha B-Crystallin in Muscle Disease Prevention: The Role of Physical Activity

HSPB5 or alpha B-crystallin (CRYAB), originally identified as lens protein, is one of the most widespread and represented of the human small heat shock proteins (sHSPs). It is greatly expressed in tissue with high rates of oxidative metabolism, such as skeletal and cardiac muscles, where HSPB5 dysfunction is associated with a plethora of human diseases. Since HSPB5 has a major role in protecting muscle tissues from the alterations of protein stability (i.e., microfilaments, microtubules, and intermediate filament components), it is not surprising that this sHSP is specifically modulated by exercise. Considering the robust content and the protective function of HSPB5 in striated muscle tissues, as well as its specific response to muscle contraction, it is then realistic to predict a specific role for exercise-induced modulation of HSPB5 in the prevention of muscle diseases caused by protein misfolding. After offering an overview of the current knowledge on HSPB5 structure and function in muscle, this review aims to introduce the reader to the capacity that different exercise modalities have to induce and/or activate HSPB5 to levels sufficient to confer protection, with the potential to prevent or delay skeletal and cardiac muscle disorders.

Classic and exertional heatstroke

In the past two decades, record-breaking heatwaves have caused an increasing number of heat-related deaths, including heatstroke, globally. Heatstroke is a heat illness characterized by the rapid rise of core body temperature above 40 °C and central nervous system dysfunction. It is categorized as classic when it results from passive exposure to extreme environmental heat and as exertional when it develops during strenuous exercise. Classic heatstroke occurs in epidemic form and contributes to 9-37% of heat-related fatalities during heatwaves. Exertional heatstroke sporadically affects predominantly young and healthy individuals. Under intensive care, mortality reaches 26.5% and 63.2% in exertional and classic heatstroke, respectively. Pathological studies disclose endothelial cell injury, inflammation, widespread thrombosis and bleeding in most organs. Survivors of heatstroke may experience long-term neurological and cardiovascular complications with a persistent risk of death. No specific therapy other than rapid cooling is available. Physiological and morphological factors contribute to the susceptibility to heatstroke. Future research should identify genetic factors that further describe individual heat illness risk and form the basis of precision-based public health response. Prioritizing research towards fundamental mechanism and diagnostic biomarker discovery is crucial for the design of specific management approaches.

Physiological Acclimatization in High-Latitude Zooplankton

How individual organisms adapt to non-optimal conditions through physiological acclimatization is central to predicting the consequences of unusual abiotic and biotic conditions such as those produced by marine heat waves. The Northeast Pacific, including the Gulf of Alaska experienced an extreme warming event (2014-2016, "The Blob") that affected all trophic levels leading to large-scale changes in the community. The marine copepod Neocalanus flemingeri is one key member of the subarctic Pacific pelagic ecosystem. During the spring phytoplankton bloom this copepod builds substantial lipid stores as it prepares for its non-feeding adult phase. A three-year comparison of gene expression profiles of copepods collected in Prince William Sound in the Gulf of Alaska between 2015 and 2017 included two high-temperature years (2015 and 2016) and one year with very low phytoplankton abundances (2016). The largest differences in gene expression were between high and low chlorophyll years, and not between warm and cool years. The observed gene expression patterns were indicative of physiological acclimatization. The predominant signal in 2016 was the down-regulation of genes involved in glycolysis and its incoming pathways, consistent with the modulation of metabolic rates in response to prolonged low food conditions. Despite the down-regulation of genes involved in metabolism, there was no evidence of suppression of protein synthesis based on gene expression or behavioral activity. Genes involved in muscle function were up-regulated, and the copepods were actively swimming and responsive to stimuli at collection. However, genes involved in fatty acid metabolism were down-regulated in 2016, suggesting reduced lipid accumulation.

Chimeric chromosome landscapes of human somatic cell cultures show dependence on stress and regulation of genomic repeats by CGGBP1

Genomes of somatic cells in culture are prone to spontaneous mutations due to errors in replication and DNA repair. Some of these errors, such as chromosomal fusions, are not rectifiable and subject to selection or elimination in growing cultures. Somatic cell cultures are thus expected to generate background levels of potentially stable chromosomal chimeras. A description of the landscape of such spontaneously generated chromosomal chimeras in cultured cells will help understand the factors affecting somatic mosaicism. Here we show that short homology-associated non-homologous chromosomal chimeras occur in normal human fibroblasts and HEK293T cells at genomic repeats. The occurrence of chromosomal chimeras is enhanced by heat stress and depletion of a repeat regulatory protein CGGBP1. We also present evidence of homologous chromosomal chimeras between allelic copies in repeat-rich DNA obtained by methylcytosine immunoprecipitation. The formation of homologous chromosomal chimeras at Alu and L1 repeats increases upon depletion of CGGBP1. Our data are derived from de novo sequencing from three different cell lines under different experimental conditions and our chromosomal chimera detection pipeline is applicable to long as well as short read sequencing platforms. These findings present significant information about the generation, sensitivity and regulation of somatic mosaicism in human cell cultures.

XENOHORMESIS UNDERLYES THE ANTI-AGING AND HEALTHY PROPERTIES OF OLIVE POLYPHENOLS

The paper provides a comprehensive and foundational mechanistic framework of hormesis that establishes its centrality in medicine and public health. This hormetic framework is applied to the assessment of olive polyphenols with respect to their capacity to slow the onset and reduce the magnitude of a wide range of age-related disorders and neurodegenerative diseases, including Alzheimer's Disease and Parkinson's Disease. It is proposed that olive polyphenol-induced anti-inflammatory protective effects are mediated in large part via the activation of AMPK and the upregulation of Nrf2 pathway. Consistently, herein we also review the importance of the modulation of Nrf2-related stress responsive vitagenes by olive polyphenols, which at low concentration according to the hormesis theory activates this neuroprotective cascade to preserve brain health and its potential use in the prevention and therapy against aging and age-related cognitive disorders in humans.

Machine learning-based predictions of dietary restriction associations across ageing-related genes

BACKGROUND

Dietary restriction (DR) is the most studied pro-longevity intervention; however, a complete understanding of its underlying mechanisms remains elusive, and new research directions may emerge from the identification of novel DR-related genes and DR-related genetic features.

RESULTS

This work used a Machine Learning (ML) approach to classify ageing-related genes as DR-related or NotDR-related using 9 different types of predictive features: PathDIP pathways, two types of features based on KEGG pathways, two types of Protein-Protein Interactions (PPI) features, Gene Ontology (GO) terms, Genotype Tissue Expression (GTEx) expression features, GeneFriends co-expression features and protein sequence descriptors. Our findings suggested that features biased towards curated knowledge (i.e. GO terms and biological pathways), had the greatest predictive power, while unbiased features (mainly gene expression and co-expression data) have the least predictive power. Moreover, a combination of all the feature types diminished the predictive power compared to predictions based on curated knowledge. Feature importance analysis on the two most predictive classifiers mostly corroborated existing knowledge and supported recent findings linking DR to the Nuclear Factor Erythroid 2-Related Factor 2 (NRF2) signalling pathway and G protein-coupled receptors (GPCR). We then used the two strongest combinations of feature type and ML algorithm to predict DR-relatedness among ageing-related genes currently lacking DR-related annotations in the data, resulting in a set of promising candidate DR-related genes (GOT2, GOT1, TSC1, CTH, GCLM, IRS2 and SESN2) whose predicted DR-relatedness remain to be validated in future wet-lab experiments.

CONCLUSIONS

This work demonstrated the strong potential of ML-based techniques to identify DR-associated features as our findings are consistent with literature and recent discoveries. Although the inference of new DR-related mechanistic findings based solely on GO terms and biological pathways was limited due to their knowledge-driven nature, the predictive power of these two features types remained useful as it allowed inferring new promising candidate DR-related genes.

The Goldilocks Principle: A Unifying Perspective on Biochemical Adaptation to Abiotic Stressors in the Sea

The ability of marine organisms to thrive over wide ranges of environmental stressors that perturb structures of proteins, nucleic acids, and lipids illustrates the effectiveness of adaptation at the biochemical level. A critical role of these adaptations is to achieve a proper balance between structural rigidity, which is necessary for maintaining three-dimensional conformation, and flexibility, which is required to allow changes in conformation during function. The Goldilocks principle refers to this balancing act, wherein structural stability and functional properties are poised at values that are just right for the environment the organism faces. Achieving this balance involves changes in macromolecular sequence and adaptive change in the composition of the aqueous or lipid milieu in which macromolecules function. This article traces the development of the field of biochemical adaptation throughout my career and shows how comparative studies of marine animals from diverse habitats have shed light on fundamental properties of life common to all organisms.

Elevated Salinity Rapidly Confers Cross-Tolerance to High Temperature in a Splash-Pool Copepod

Accurate forecasting of organismal responses to climate change requires a deep mechanistic understanding of how physiology responds to present-day variation in the physical environment. However, the road to physiological enlightenment is fraught with complications: predictable environmental fluctuations of any single factor are often accompanied by substantial stochastic variation and rare extreme events, and several factors may interact to affect physiology. Lacking sufficient knowledge of temporal patterns of co-variation in multiple environmental stressors, biologists struggle to design and implement realistic and relevant laboratory experiments. In this study, we directly address these issues, using measurements of the thermal tolerance of freshly collected animals and long-term field records of environmental conditions to explore how the splash-pool copepod Tigriopus californicus adjusts its physiology as its environment changes. Salinity and daily maximum temperature-two dominant environmental stressors experienced by T. californicus-are extraordinarily variable and unpredictable more than 2-3 days in advance. However, they substantially co-vary such that when temperature is high salinity is also likely to be high. Copepods appear to take advantage of this correlation: median lethal temperature of field-collected copepods increases by 7.5°C over a roughly 120 parts-per-thousand range of ambient salinity. Complementary laboratory experiments show that exposure to a single sublethal thermal event or to an abrupt shift in salinity also elicits rapid augmentation of heat tolerance via physiological plasticity, although the effect of salinity dwarfs that of temperature. These results suggest that T. californicus's physiology keeps pace with the rapid, unpredictable fluctuations of its hypervariable physical environment by responding to the cues provided by recent sublethal stress and, more importantly, by leveraging the mechanistic cross-talk between responses to salinity and heat stress.

Is Telomere Length Shortening a Risk Factor for Neurodegenerative Disorders?

Telomeres are located at the end of chromosomes. They are known to protect chromosomes and prevent cellular senescence. Telomere length shortening has been considered an important marker of aging. Many studies have reported this concept in connection with neurodegenerative disorders. Considering the role of telomeres, it seems that longer telomeres are beneficial while shorter telomeres are detrimental in preventing neurodegenerative disorders. However, several studies have shown that people with longer telomeres might also be vulnerable to neurodegenerative disorders. Before these conflicting results can be explained through large-scale longitudinal clinical studies on the role of telomere length in neurodegenerative disorders, it would be beneficial to simultaneously review these opposing results. Understanding these conflicting results might help us plan future studies to reveal the role of telomere length in neurodegenerative disorders. In this review, these contradictory findings are thoroughly discussed, with the aim to better understand the role of telomere length in neurodegenerative disorders.

Neural functions of small heat shock proteins

Stress response is a cellular widespread mechanism encoded by a common protein program composed by multiple cellular factors that converge in a defense reaction to protect the cell against damage. Among many mechanisms described, heat shock proteins were proposed as universally conserved protective factors in the stress core proteome, coping with different stress stimuli through its canonical role in protein homeostasis. However, emerging evidences reveal non-canonical roles of heat shock proteins relevant for physiological and pathological conditions. Here, we review the implications of inducible heat shock proteins in the central nervous system physiology. In particular, we discuss the relevance of heat shock proteins in the maintenance of synapses, as a balanced protective mechanism in central nervous system development, pathological conditions and aging.

Deciphering the mechanism by which the yeast Phaffia rhodozyma responds adaptively to environmental, nutritional, and genetic cues

Phaffia rhodozyma is a basidiomycetous yeast that synthesizes astaxanthin (ASX), which is a powerful and highly valuable antioxidant carotenoid pigment. P. rhodozyma cells accrue ASX and gain an intense red-pink coloration when faced with stressful conditions such as nutrient limitations (e.g., nitrogen or copper), the presence of toxic substances (e.g., antimycin A), or are affected by mutations in the genes that are involved in nitrogen metabolism or respiration. Since cellular accrual of ASX occurs under a wide variety of conditions, this yeast represents a valuable model for studying the growth conditions that entail oxidative stress for yeast cells. Recently, we proposed that ASX synthesis can be largely induced by conditions that lead to reduction-oxidation (redox) imbalances, particularly the state of the NADH/NAD+ couple together with an oxidative environment. In this work, we review the multiple known conditions that elicit ASX synthesis expanding on the data that we formerly examined. When considered alongside the Mitchell's chemiosmotic hypothesis, the study served to rationalize the induction of ASX synthesis and other adaptive cellular processes under a much broader set of conditions. Our aim was to propose an underlying mechanism that explains how a broad range of divergent conditions converge to induce ASX synthesis in P. rhodozyma. The mechanism that links the induction of ASX synthesis with the occurrence of NADH/NAD+ imbalances may help in understanding how other organisms detect any of a broad array of stimuli or gene mutations, and then adaptively respond to activate numerous compensatory cellular processes.

Transcriptome analysis and potential mechanisms of bovine oocytes under seasonal heat stress

Heat stress is the major factor affecting cattle fertility but molecular mechanisms of deleterious impacts of elevated temperature on oocyte are still not well known. Therefore, the aim of this study is to gain a better understanding of the underlying molecular mechanism of how heat stress affects GV-stage and MII-stage oocytes and discover hub genes to heat resistance for cow oocytes. In this study, we used the bioinformatics approach to discover the differentially expressed genes between GV-stage and MII-stage oocytes, which were collected during spring and summer. When GV-stage oocytes were compared to MII-stage oocytes collected in July (Jul DEGs group) a total of 1068 genes were found as differentially expressed as a result of heat stress. Also, HSPA8, COPS5, POLR2L, PSMC6, and TPI1 were identified as the common top ranked genes for the Jul DEGs group. The highest connected hub gene for the Jul DEGs group was determined as HSPA8. Our results showed that different heat response mechanisms might be activated to protect oocytes from elevated temperatures in cattle. The identified genes and their associated pathways might play an important role in the response to heat stress that affects the oocytes in cattle.

Terahertz exposure enhances neuronal synaptic transmission and oligodendrocyte differentiation in vitro

Terahertz (THz) frequency occupies a large portion of the electromagnetic spectrum that is between the infrared and microwave regions. Recent advances in THz application have stimulated interests regarding the biological effects within this frequency range. In the current study, we report that irradiation with a single-frequency THz laser on mice cortical neuron cultures increases excitatory synaptic transmission and neuronal firing activities. Microarray assay reveals gene expression dynamics after THz exposure, which is consistent with morphology and electrophysiology results. Besides, certain schedule of THz irradiation inhibits the proliferation of oligodendrocyte precursor cells (OPCs) and promotes OPC differentiation. Of note, the myelination process is enhanced after THz exposure. In summary, our observations suggest that THz irradiation can modulate the functions of different neuronal cells, with different sensitivity to THz. These results provide important understanding of the mechanisms that govern THz interactions with nervous systems and suggest THz wave as a new strategy for neuromodulation.

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THz irradiation increases excitatory synaptic transmission and neuronal firing

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Microarray assay reveals neuronal gene expression dynamics after THz exposure

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THz irradiation promotes the maturation of oligodendrocytes

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The myelination process in neuron is enhanced after THz exposure

Extracellular vesicle-associated small heat shock proteins as therapeutic agents in neurodegenerative diseases and beyond

Increasing evidence points towards using extracellular vesicles (EVs) as a therapeutic strategy in neurodegenerative diseases such as multiple sclerosis, Parkinson's, and Alzheimer's disease. EVs are nanosized carriers that play an essential role in intercellular communication and cellular homeostasis by transporting an active molecular cargo, including a large variety of proteins. Recent publications demonstrate that small heat shock proteins (HSPBs) exhibit a beneficial role in neurodegenerative diseases. Moreover, it is defined that HSPBs target the autophagy and the apoptosis pathway, playing a prominent role in chaperone activity and cell survival. This review elaborates on the therapeutic potential of EVs and HSPBs, in particular HSPB1 and HSPB8, in neurodegenerative diseases. We conclude that EVs and HSPBs positively influence neuroinflammation, central nervous system (CNS) repair, and protein aggregation in CNS disorders. Moreover, we propose the use of HSPB-loaded EVs as advanced nanocarriers for the future development of neurodegenerative disease therapies.

Transcriptome analysis provides the first insight into the molecular basis of temperature plasticity in Banggai cardinalfish, Pterapogon kauderni

Banggai cardinalfish, Pterapogon kauderni, is a tropical fish listed as an endangered species by IUCN. Its distribution and survival condition are extremely limited, and the changes of living environment caused by global warming may seriously threaten its geographical distribution. In order to understand the survival temperature range and the potential mechanism of temperature plasticity of P. kauderni, transcriptome analysis was performed under five temperature conditions (18 °C, 22 °C, 26 °C, 30 °C and 34 °C). A total of 432,444,497 clean reads were obtained from the mix tissues of whole head, viscera (except intestine), and muscle. All clean data were spliced into 194,832 unigenes. Compared with 26 °C, 57, 107, 187 and 174 differentially expressed genes (DEGs) were obtained at 18 °C, 22 °C, 30 °C and 34 °C, respectively. Gene Ontology (GO) analysis showed the most highly enriched in the DEGs were cellular processes, binding, metabolic processes and biological regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated circadian rhythm, protein processing in endoplasmic reticulum, influenza A and prion disease were significantly enriched. 47 genes that may be related to temperature stress were identified, such as Per1, MLP, IGFBP1, HSP70, HSP90α, HSPA4, DNAJB1, CALR. This is the first RNA-Seq study of P. kauderni. This information should be valuable for further targeted studies on temperature tolerance, thereby assisting the protection and development of P. kauderni.

Chlorine-stressed Salmonella cells are significantly more engulfed by Acanthamoeba trophozoites and have a longer intracystic survival than the non-stressed cells

In the present study, the effect of sublethal chlorine-induced oxidative stress on the subsequent interaction of Salmonella enterica serovars Enteritidis and Typhimurium with Acanthamoeba castellanii and A. polyphaga was evaluated. Sublethal chlorine concentration was determined using the lag phase extension information and used to prepare chlorine-stressed Salmonella cells. Coculture experiments of Acanthamoeba and Salmonella cells were performed in Page's amoeba saline (PAS) at 25 °C for 2 h. The results showed that the chlorine-stressed Salmonella cells were significantly more engulfed by A. castellanii and A. polyphaga trophozoites than the non-stressed cells. The uptake rates of the chlorine-stressed and non-stressed Salmonella cells were in the range of 14.17-27.34 and 6.51-11.52% for A. castellanii, and in the range of 8.32-17.76 and 2.28-6.12% for A. polyphaga trophozoites, respectively. Moreover, intracystic survival time of chlorine-stressed cells of S. Enteritidis and S. Typhimurium was significantly longer than that of non-stressed cells. While, non-stressed Salmonella cells survived within A. castellanii and A. polyphaga cysts for 13-20 and 8-15 days, chlorine-stressed cells were recovered from A. castellanii and A. polyphaga cysts after 22-32 and 15-24 days, respectively. These results underscore the importance of bacterial exposure to sublethal chlorine concentrations in their interaction with free-living amoebae, and may lead to a better understanding of the parameters affecting the persistence of Salmonella enterica serovars in food-related environments.

Psychiatric hospitalization during the two SARS-CoV-2 pandemic waves: New warnings for acute psychotic episodes and suicidal behaviors

BACKGROUND

The subsequent waves of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic have represented a dramatic health emergency characterized by significant consequences on mental health. Diachronic variations in the incidence rates of acute relapse of psychiatric disorders may represent significant "sentinel events" for assessing the mental health response to an unprecedented stressful event.

AIM

To investigate the variation in psychiatric hospitalization rates and differences in sociodemographic and clinical-psychopathological peculiarities at Bologna "Maggiore" General Hospital Psychiatric Ward (GHPW) between the first two waves SARS-CoV-2 pandemic and the same periods of the previous 3 years. The secondary purpose of the study was to suggest a diachronic response pathway to stress by reporting additional literature data on coping strategies.

METHODS

This observational and retrospective study collected information on admission to the GHPW at the "Maggiore" Hospital in Bologna in the index periods defined as follows: the first period between February 24, 2020 and April 30, 2020 (first epidemic wave) and the second period between October 8, 2020, and January 7, 2021 (second pandemic wave). Absolute numbers and proportion of admitted patients, their sociodemographic and clinical-psychopathological characteristics were compared with the same parameters recorded in the two same periods of the previous 3 years. No strict inclusion or exclusion criteria were provided in the data collection to collect information on all patients requiring acute psychiatric hospitalization.

RESULTS

During the first wave, there was a significant reduction in hospitalization rates, although there was a simultaneous increase in compulsory hospitalizations and the acute relapse of schizophrenia spectrum and other psychotic disorders. During the second wave, hospitalization rates reached those recorded during the same period of the previous 3 years, mainly due to the rise of bipolar and related disorders, depressive disorders, anxiety disorders, trauma- and stressor-related disorders and suicidal behaviors.

CONCLUSION

The coping strategies adopted during the first wave of the SARS-CoV-2 pandemic protected the vulnerable population from the general risk of clinical-psychopathological acute relapse, even if they increased the susceptibility to run into schizophrenia spectrum and other psychotic disorder relapses. In the medium-long term (as in the second pandemic wave), the same strategies do not play protective roles against the stress associated with the pandemic and social restriction measures. Indeed, during the second wave of the SARS-CoV-2 pandemic, an increase in total hospitalization rate, suicidal behaviors and the incidence rate of bipolar and related disorders, depressive disorders, anxiety disorders, trauma- and stressor-related disorders was observed.

The glycine betaine role in neurodegenerative, cardiovascular, hepatic, and renal diseases: Insights into disease and dysfunction networks

Glycine betaine (N, N, N-trimethyl amine) is an osmolyte accumulated in cells that is key for cell volume and turgor regulation, is the principal methyl donor in the methionine cycle and is a DNA and proteins stabilizer. In humans, glycine betaine is synthesized from choline and can be obtained from some foods. Glycine betaine (GB) roles are illustrated in chemical, metabolic, agriculture, and clinical medical studies due to its chemical and physiological properties. Several studies have extensively described GB role and accumulation related to specific pathologies, focusing mainly on analyzing its positive and negative role in these pathologies. However, it is necessary to explain the relationship between glycine betaine and different pathologies concerning its role as an antioxidant, ability to methylate DNA, interact with transcription factors and cell receptors, and participate in the control of homocysteine concentration in liver, kidney and brain. This review summarizes the most important findings and integrates GB role in neurodegenerative, cardiovascular, hepatic, and renal diseases. Furthermore, we discuss GB impact on other dysfunctions as inflammation, oxidative stress, and glucose metabolism, to understand their cross-talks and provide reliable data to establish a base for further investigations.

Large within, and between, species differences in marine cellular responses: Unpredictability in a changing environment

Predicting the impacts of altered environments on future biodiversity requires a detailed understanding of organism responses to change. To date, studies evaluating mechanisms underlying marine organism stress responses have largely concentrated on oxygen limitation and the use of heat shock proteins as biomarkers. However, whether these biomarkers represent responses that are consistent across species and different environmental stressors remains open to question. Here we show that responses to four different thermal stresses (three rates of thermal ramping (1 °C h^-1, 1 °C day^-1 or 1 °C 3 day^-1) and a three-month acclimation to warming of 2 °C) applied to three species of Antarctic marine invertebrate produced highly individual responses in gene expression profiles, both within and between species. Mapping the gene expression profiles from each treatment for each of the three species, identified considerable difference in numbers of differentially regulated transcripts ranging from 10 to 3011. When these data were correlated across the different temperature treatments, there was no evidence for a common response with only 0-2 transcripts shared between all four treatments within any one species. There were also no shared differentially expressed genes across species, even at the same thermal ramping rates. The classical cellular stress response (CSR) i.e. up-regulation of heat shock proteins, was only strongly present in two species at the fastest ramping rate of 1 °C h^-1, albeit with different sets of stress genes expressed in each species. These data demonstrate the wide variability in response to warming at the molecular level in marine species. Therefore, identification of biodiversity stress responses engendered by changing conditions will require evaluation at the species level using targeted key members of the ecosystem, strongly correlated to the local biotic and abiotic factors.

COVID-19: A Redox Disease-What a Stress Pandemic Can Teach Us About Resilience and What We May Learn from the Reactive Species Interactome About Its Treatment

Significance: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing coronavirus disease 2019 (COVID-19), affects every aspect of human life by challenging bodily, socioeconomic, and political systems at unprecedented levels. As vaccines become available, their distribution, safety, and efficacy against emerging variants remain uncertain, and specific treatments are lacking. Recent Advances: Initially affecting the lungs, COVID-19 is a complex multisystems disease that disturbs the whole-body redox balance and can be long-lasting (Long-COVID). Numerous risk factors have been identified, but the reasons for variations in susceptibility to infection, disease severity, and outcome are poorly understood. The reactive species interactome (RSI) was recently introduced as a framework to conceptualize how cells and whole organisms sense, integrate, and accommodate stress. Critical Issues: We here consider COVID-19 as a redox disease, offering a holistic perspective of its effects on the human body, considering the vulnerability of complex interconnected systems with multiorgan/multilevel interdependencies. Host/viral glycan interactions underpin SARS-CoV-2's extraordinary efficiency in gaining cellular access, crossing the epithelial/endothelial barrier to spread along the vascular/lymphatic endothelium, and evading antiviral/antioxidant defences. An inflammation-driven "oxidative storm" alters the redox landscape, eliciting epithelial, endothelial, mitochondrial, metabolic, and immune dysfunction, and coagulopathy. Concomitantly reduced nitric oxide availability renders the sulfur-based redox circuitry vulnerable to oxidation, with eventual catastrophic failure in redox communication/regulation. Host nutrient limitations are crucial determinants of resilience at the individual and population level. Future Directions: While inflicting considerable damage to health and well-being, COVID-19 may provide the ultimate testing ground to improve the diagnosis and treatment of redox-related stress diseases. "Redox phenotyping" of patients to characterize whole-body RSI status as the disease progresses may inform new therapeutic approaches to regain redox balance, reduce mortality in COVID-19 and other redox diseases, and provide opportunities to tackle Long-COVID. Antioxid. Redox Signal. 35, 1226-1268.

Urapidil alleviates ovarian torsion detorsion injury via regulating oxidative stress, apoptosis, autophagia, and inflammation

Objective(s):

This study aimed to determine anti-inflammatory, antioxidant, and antiapoptotic properties of urapidil (Ura) against ovarian torsion detorsion (T/D) injury in rats.

Materials and Methods:

40 female Wistar albino rats were grouped as sham, T/D, T/D+dimethyl sulfoxide (DMSO), T/D+Urapidil (Ura) 0.5 mg/kg (low dose), and T/D+Urapidil (Ura) 5 mg/kg (high dose) groups. In treatment groups, Ura was administered intraperitoneally just before detorsion. Biochemical parameters (TAS, TOS, MDA, MPO, and SOD) and immunohistochemical (IL-1β, TNF-α, NF-κB, LC3B, and Caspase-3) analyzes were performed.

Results:

In the T/D group, OSI and MPO levels were elevated significantly while TAS values decreased compared with the sham group. A significant difference occurred in the low dose treatment group in TAS and OSI levels compared with the T/D group. In the high dose treatment group, significant elevation in TAS but reduction in OSI and MDA levels were observed compared with the T/D group. Immunohistochemical staining resulted in IL-1β, TNF-α, NF-κB, LC3B, and caspase-3 immunopositivity in the T/D group, while Ura treatment decreased those parameters. Intensive congestion and hemorrhage were observed in the T/D group, but contrary to this, treatment groups had alleviated congestion and hemorrhage.

Conclusion:

These results suggest that Ura demonstrated protective effects against ovarian T/D injury via anti-oxidative, anti-inflammatory, and anti-apoptotic features.

An integrated, multi-level analysis of thermal effects on intertidal molluscs for understanding species distribution patterns

Elucidating the physiological mechanisms that underlie thermal stress and discovering how species differ in capacities for phenotypic acclimatization and evolutionary adaptation to this stress is critical for understanding current latitudinal and vertical distribution patterns of species and for predicting their future state in a warming world. Such mechanistic analyses require careful choice of study systems (species and temperature-sensitive traits) and design of laboratory experiments that reflect the complexities of in situ conditions. Here, we critically review a wide range of studies of intertidal molluscs that provide mechanistic accounts of thermal effects across all levels of biological organization - behavioural, organismal, organ level, cellular, molecular, and genomic - and show how temperature-sensitive traits govern distribution patterns and capacities for coping with thermal stress. Comparisons of congeners from different thermal habitats are especially effective means for identifying adaptive variation. We employ these mechanistic analyses to illustrate how species differ in the severity of threats posed by rising temperature. Counterintuitively, we show that some of the most heat-tolerant species may be most threatened by increases in temperatures because of their small thermal safety margins and minimal abilities to acclimatize to higher temperatures. We discuss recent molecular biological and genomic studies that provide critical foundations for understanding the types of evolutionary changes in protein structure, RNA secondary structure, genome content, and gene expression capacities that underlie adaptation to temperature. Duplication of stress-related genes, as found in heat-tolerant molluscs, may provide enhanced capacity for coping with higher temperatures. We propose that the anatomical, behavioural, physiological, and genomic diversity found among intertidal molluscs, which commonly are of critical importance and high abundance in these ecosystems, makes this group of animals a highly appropriate study system for addressing questions about the mechanistic determinants of current and future distribution patterns of intertidal organisms.