Dynamic Phosphoproteome Profiling of Zebrafish Embryonic Fibroblasts during Cold Acclimation

Temperature affects almost all aspects of the fish life. To cope with low temperature, fish have evolved the ability of cold acclimation for survival. However, intracellular signaling events underlying cold acclimation in fish remain largely unknown. Here, the formation of cold acclimation in zebrafish embryonic fibroblasts (ZF4) is monitored and the phosphorylation events during the process are investigated through a large‐scale quantitative phosphoproteomic approach. In total, 11 474 phosphorylation sites are identified on 4066 proteins and quantified 5772 phosphosites on 2519 proteins. Serine, threonine, and tyrosine (Ser/Thr/Tyr) phosphorylation accounted for 85.5%, 13.3%, and 1.2% of total phosphosites, respectively. Among all phosphosites, 702 phosphosites on 510 proteins show differential regulation during cold acclimation of ZF4 cells. These phosphosites are divided into six clusters according to their dynamic changes during cold exposure. Kinase–substrate prediction reveals that mitogen‐activated protein kinase (MAPK) among the kinase groups is predominantly responsible for phosphorylation of these phosphosites. The differentially regulated phosphoproteins are functionally associated with various cellular processes such as regulation of actin cytoskeleton and MAPK signaling pathway. These data enrich the database of protein phosphorylation sites in zebrafish and provide key clues for the elucidation of intracellular signaling networks during cold acclimation of fish.     

Climate‐dependent variation in cold tolerance of weedy rice and rice mediated by OsICE1 promoter methylation

The mechanisms by which weedy rice (Oryza sativa f. spontanea) has adapted to endure low‐temperature stress in northern latitudes remain unresolved. In this study, we assessed cold tolerance of 100 rice varieties and 100 co‐occurring weedy rice populations, which were sampled across a broad range of climates in China. A parallel pattern of latitude‐dependent variation in cold tolerance was detected in cultivated rice and weedy rice. At the molecular level, differential cold tolerance was strongly correlated with relative expression levels of CBF cold response pathway genes and with methylation levels in the promoter region of OsICE1, a regulator of this pathway. Among all methylated cytosine sites of the OsICE1 promoter, levels of CHG and CHH methylation were found to be significantly correlated with cold tolerance among accessions. Furthermore, within many of the collection locales, weedy rice shared identical or near‐identical OsICE1 methylation patterns with co‐occurring cultivated rice. These findings provide new insights on the possible roles that methylation variation in the OsICE1 promoter may play in cold tolerance, and they suggest that weedy rice can rapidly acquire cold tolerance via methylation patterns that are shared with co‐occurring rice cultivars.     

早期介入高压氧提高寒冷应激下小鼠存活率并促进创面愈合的研究

暴露于寒冷环境下的皮肤开放性伤口是一种高度危险的战场创伤,威胁在室外作业的人员健康。紧急治疗中,高压氧(hyperbaric oxygen, HBO)治疗已经证实能够安全有效地促进皮肤伤口愈合。然而,HBO治疗的最佳干预时间说法仍然并不统一。使用冷应激下的小鼠背部皮肤全层缺损创面模型,比较了HBO治疗的3种干预策略,即分别为创伤后0、24和48 h介入HBO。结果显示,创后立即实施高压氧治疗(0-hHBO组)降低死亡率的效果最佳,小鼠死亡率为33%,而对照组死亡率为100%,且0-hHBO组创面愈合率第5天已达到85%。进一步的血常规和组织免疫化学检测显示,0-hHBO治疗组改善了血液指标,并发挥了一定的抗凋亡作用,这种作用尤其在表皮干细胞中更为明显。因此,研究结果将为HBO的临床应用提供重要的实验数据和线索。     

The effects of population and thermal acclimation on the growth,condition and cold responsive mRNA expression of age-0 lake sturgeon (Acipenser fulvescens)

In Manitoba, Canada, wild lake sturgeon (Acipenser fulvescens) populations exist along a latitudinal gradient and are reared in hatcheries to bolster threatened populations. We reared two populations of lake sturgeon, one from each of the northern and southern ends of Manitoba and examined the effects of typical hatchery temperatures (16°C) as well as 60-day acclimation to elevated rearing temperatures (20°C) on mortality, growth and condition throughout early development. Additionally, we examined the cold shock response, which may be induced during stocking, through the hepatic mRNA expression of genes involved in the response to cold stress and homeoviscous adaptation (HSP70, HSP90a, HSP90b, CIRP and SCD). Sturgeon were sampled after 1 day and 1 week following stocking into temperatures of 8, 6 and 4°C in a controlled laboratory environment. The southern population showed lower condition and higher mortality during early life than the northern population while increased rearing temperature impacted the growth and condition of developing northern sturgeon. During the cold shock, HSP70 and HSP90a mRNA expression increased in all sturgeon treatments as stocking temperature decreased, with higher expression observed in the southern population. Expression of HSP90b, CIRP and SCD increased as stocking temperature decreased in northern sturgeon with early acclimation to 20°C. Correlation analyses indicated the strongest molecular relationships were in the expression of HSP90b, CIRP and SCD, across all treatments, with a correlation between HSP90b and body condition in northern sturgeon with early acclimation to 20°C. Together, these observations highlight the importance of population and rearing environment throughout early development and on later cellular responses induced by cold stocking temperatures.     

Impact of short‐term exposure to low subzero temperatures on egg hatch in the hemlock looper,Lambdina fiscellaria

The frequency of extreme events, such as cold spells, is expected to increase under global warming. Therefore, the ability of insects to survive rapid changes in temperature is an important aspect to investigate in current population ecology. The hemlock looper (HL), Lambdina fiscellaria (Guenée) (Lepidoptera: Geometridae), a defoliator of boreal balsam fir forests in eastern Canada, overwinters at the egg stage on tree trunks and branches where eggs can be exposed to very low subzero air temperatures. Using eggs from the island of Newfoundland (NL) and Quebec mainland (QC), we undertook field and laboratory experiments to determine: (1) their supercooling point (SCP) in mid‐January and mid‐February; (2) overwintering mortality; (3) cold tolerance to various combinations of subzero temperatures (?25, ?30, ?33, ?35, or ?37 °C) and exposure durations (2, 4, 8, 12, or 16 h); and (4) potential causes of death at subzero temperatures above the SCP. Regardless of population or sampling date, eggs supercooled on average at ?40.1 °C. In the field, 59% of eggs from either population that overwintered in Sainte‐Foy (QC) and Corner Brook (NL) hatched successfully, whereas none did in Armagh (QC) or Epaule (QC). In the laboratory, 50% of eggs survived after 4 h at ?34.4 °C or after 14 h at ?32.9 °C. In contrast, regardless of exposure duration, >50% of eggs hatched at temperatures ≥?33 °C, but <50% did so at ≤?35 °C, suggesting high pre‐freeze mortality. However, when eggs were attached to thermocouples and exposed to temperatures ranging from ?25 to ?37 °C for 16 h, 69% froze at temperatures of ?35 to ?37 °C, but only 2% did at ?25 or ?30 °C. Time to freeze decreased as subzero temperatures declined, and this was more evident in island eggs than in mainland eggs. Overall, eggs can freeze after a brief exposure to subzero temperatures higher than the standard SCP, and are thus highly vulnerable to cold spells.     

Physio-biochemical and proteome analysis of chickpea in early phases of cold stress

Intensive and short-term strategies can aid in more rapid screening with informative and reliable results for long-term investigations under cold stress (CS). The integration of cellular analysis of chickpea during 0, 2, 4, 8, and 12 h CS supplied us with novel possible responsive components and the possible interactions embedded inside, still remaining a Maze. Seedlings showed a biphasic pattern of responses over time. The transitory phase happened after 8 h, when cells are presumably experiencing a new stage of responses and setting the stage for long-term adjustments. Physio-biochemical analysis confirmed the direct effect of fatty acids composition, lipoxygenase activity and antioxidant systems in cell responses under CS. Also, proteome results using MALDI-TOF-TOF and/or LC–MS/MS were able to differentiate changes in early phases of CS. Two-dimensional gel analysis results showed the possible targets of CS as mitochondria, chloroplast, organelle–nucleus communications, storage resources, stress and defense, protein degradation and signal transduction that confirmed the cell intended to re-establish a new homeostasis, in energy and primary metabolites to adapt to long-term CS. Here we propose a time course dynamic assessing multi-dimensional approaches for CS studies as one of the first studies in short-term treatment to progressively fill in the gaps between physio-biochemical and molecular events and touch the cell architecture for a better comprehension of the nature of plant stress response.     

Conditional cold avoidance drives between-population variation in germination behaviour in Calluna vulgaris

Background and Aims

Across their range, widely distributed species are exposed to a variety of climatic and other environmental conditions, and accordingly may display variation in life history strategies. For seed germination in cold climates, two contrasting responses to variation in winter temperature have been documented: first, an increased ability to germinate at low temperatures (cold tolerance) as winter temperatures decrease, and secondly a reduced ability to germinate at low temperatures (cold avoidance) that concentrates germination towards the warmer parts of the season.

Methods

Germination responses were tested for Calluna vulgaris, the dominant species of European heathlands, from ten populations collected along broad-scale bioclimatic gradients (latitude, altitude) in Norway, covering a substantial fraction of the species'' climatic range. Incubation treatments varied from 10 to 25 °C, and germination performance across populations was analysed in relation to temperature conditions at the seed collection locations.

Key Results

Seeds from all populations germinated rapidly and to high final percentages under the warmer incubation temperatures. Under low incubation temperatures, cold-climate populations had significantly lower germination rates and percentages than warm-climate populations. While germination rates and percentages also increased with seed mass, seed mass did not vary along the climatic gradients, and therefore did not explain the variation in germination responses.

Conclusions

Variation in germination responses among Calluna populations was consistent with increased temperature requirements for germination towards colder climates, indicating a cold-avoidance germination strategy conditional on the temperature at the seeds'' origin. Along a gradient of increasing temperatures this suggests a shift in selection pressures on germination from climatic adversity (i.e. low temperatures and potential frost risk in early or late season) to competitive performance and better exploitation of the entire growing season.