Mechanisms Of Cold Adaptation Research Articles

Fibroblast Growth Factor-9 Regulates Adaptive Brown Adipose Tissue Mass Expansion

Brown adipose tissue (BAT) plays an essential role in adaptive thermogenesis in response to environmental changes, such as cold and diet. Targeting BAT and modulating its mass and/or energy-dissipating capacity hold great promise for treatment of metabolic disorders. Expansion of BAT mass through increased cellular proliferation is a fundamental mechanism of cold adaptation. We have recently discovered Fibroblast Growth Factor 9 (FGF-9) as a cold-induced adipokine produced by BAT that regulates BAT mass. Adeno-associated virus (AAV)-mediated overexpression of FGF-9 in vivo increased BAT mass and improved glucose metabolism in obese mice. Additionally, using double thymidine analogue labeling we demonstrated that FGF-9 overexpression in BAT increased cellular proliferation and enhanced cold-induced BAT expansion. Using an adipose tissue-specific Cas9 knock-in mouse model coupled with the AAV-mediated delivery of gRNAs targeting FGF-9, we specifically deleted FGF-9 in BAT and demonstrated that loss of FGF-9 resulted in reduction of cold-induced proliferation of brown adipocyte progenitors, and led to impaired thermogenic capacity. Therefore, FGF-9 is essential for cold-induced formation of new brown adipocytes and long term cold adaptation. Combining the results from these gain- and loss-of-function studies, we conclude that FGF-9 acts as a growth factor for brown adipocyte progenitors to promote BAT expansion in response to cold. These findings provide a novel regulatory mechanism modulating BAT mass, and may ultimately contribute to the development of novel therapeutic strategies to combat obesity and its comorbidities. Disclosure F. Shamsi: None. T. Huang: None. Y. Tseng: Other Relationship; Self; Chugai Pharmaceutical Co., Ltd.. Research Support; Self; MedImmune.

The Main Physiological Mechanisms of Cold Adaptation in Humans

This article reviews published data on the main types of adaptation of humans to cold and the mechanisms increasing heat production. Studies in recent years addressing the molecular mechanisms of adaptation to cold are shown to confirm results from earlier physiological investigations demonstrating that the main contribution to adaptive thermogenesis on cooling is provided by oxidative fibers in skeletal muscle (birds, marsupials, large placental mammals, and humans) and brown fat (small placental mammals, particularly rodents). The main increase in heat production occurs as a result of contractile activity (shivering and thermoregulatory muscle tone), uncoupling of oxidative phosphorylation, and decreases in the efficiency (energy conversion efficiency, ECE) of cellular pumps (ATPases), which is induced by noradrenaline and thyroid hormones and is accompanied by increases in the consumption of oxygen and energy substrates. Prolonged cold adaptation leads to increases in the number and activity of mitochondria to provide for increasing levels of ATP consumption.

Isolation and characterization of two lytic cold-active bacteriophages infecting Pseudomonas fluorescens from the Napahai plateau wetland.

As the "kidneys of the Earth", wetlands play important roles as biodiversity reservoirs, in water purification, and in flood control. In this study, 2 lytic cold-active bacteriophages, named VW-6S and VW-6B, infecting Pseudomonas fluorescens W-6 cells from the Napahai plateau wetland in China were isolated and characterized. Electron microscopy showed that both VW-6S and VW-6B had an icosahedral head (66.7 and 61.1 nm, respectively) and a long tail (8.3 nm width × 233.3 nm length and 11.1 nm width × 166.7 nm length, respectively). The bacteriophages VW-6S and VW-6B were classified as Siphoviridae and had an approximate genome size of 30-40 kb. The latent and burst periods of VW-6S were 60 and 30 min, whereas those of VW-6B were 30 and 30 min, respectively. The optimal pH values for the bacteriophages VW-6S and VW-6B were 8.0 and 10.0, respectively, and their activity decreased rapidly at temperatures higher than 60 °C. These cold-active bacteriophages provide good materials for further study of cold-adaptation mechanisms and interaction with the host P. fluorescens.

40 Gene Expression Profiling of In Vitro-Produced Blastocysts Derived from In Vitro-Matured Bovine Oocytes Vitrified/Warmed in Media Supplemented with a Biopolymer Produced by an Antarctic Bacterium

Previous reports have demonstrated the beneficial effect of antifreeze glycoprotein supplementation during oocyte vitrification on preventing ice crystal formation and thus enhancing developmental competence after vitrification-warming. Pseudomonas sp. ID1, a bacterium isolated from marine sediment from Antarctica, produces an exopolysaccharide, M1 EPS, as a cold adaptation mechanism. Despite numerous studies on structural and morphological damages induced by cryopreservation in oocytes, few studies have focused on the impact of vitrification on the expression pattern of genes during early embryo development. In the present study, the expression patterns of 6 genes (BAX, BCL2-like 1, DNMT3A, UBE2A, SCLC2A3, and HDAC1) were investigated in Day 8 blastocysts resulting from in vitro-matured oocytes vitrified/warmed in media supplemented with various concentrations of M1 EPS. After 21 h of IVM, 1,062 oocytes were vitrified/warmed in media supplemented with 0, 0.001, 0.01, 0.1, and 1 mg mL−1 M1 EPS. At 24 h of IVM, oocytes were in vitro fertilized and in vitro cultured and the resulting blastocysts were harvested at Day 8 for RNA extraction and qPCR analysis. Fresh, non-vitrified oocytes were used as a control. Analysis of gene expression was performed through Kruskall-Wallis test and followed by Mann-Whitney test, and the level of significance was set at P ≤ 0.05. No significant differences were detected in relative mRNA abundance for SLC2A3, UBE2A, or HDAC-1 between blastocysts derived from vitrified oocytes, regardless of M1 EPS treatment. Expression of DNMT3A was significantly higher in embryos obtained from oocytes vitrified and warmed with 0.1 mg mL−1 M1 EPS compared with other treatment groups. However, no differences in DNMT3A expression were observed when the other vitrified groups were compared. The relative abundance of BAX transcript in embryos from oocytes vitrified in media supplemented with 0.1 mg mL−1 M1 EPS was higher than that in 0 or 0.001 mg mL−1 groups. Embryos from 0.01 and 0.1 mg mL−1 groups showed higher BCL2-like 1 mRNA abundance than those from the 0, 0.001, and 1 mg mL−1 groups. Whereas blastocysts from oocytes vitrified with 0.01 mg mL−1 M1 EPS exhibited the lowest BAX:BCL2-like 1 ratio, no significant differences in BAX:BCL2-like 1 ratio were observed between the other treatments. The significantly lower BAX:BCL2 ratio observed in blastocysts obtained from oocytes vitrified with 0.01 mg mL−1 M1 EPS could be indicative for a better embryo quality. Although optimizing the use of M1 EPS may benefit oocyte cryopreservation protocols, further research is required to clarify the exact mechanism through which it exerts its protective role. This study was supported by the Spanish Ministry of Science and Innovation (Project AGL2016-79802-P and grant CTQ2014-59632-R).

Effect of Low Temperature Cultivation on the Phytochemical Profile and Bioactivity of Arctic Plants: A Case of Dracocephalum palmatum.

The influence of climatic factors, e.g., low temperature, on the phytochemical composition and bioactivity of the arctic plant Dracocephalum palmatum Steph. ax Willd. (palmate dragonhead), a traditional food and medical herb of Northern Siberia, was investigated. D. palmatum seedlings were grown in a greenhouse experiment at normal (20 °C, NT) and low (1 °C, LT) temperature levels and five groups of components that were lipophilic and hydrophilic in nature were characterized. The analyses indicated that D. palmatum under NT demonstrates high content of photosynthetic pigments, specific fatty acid (FA) profile with domination of saturated FA (53.3%) and the essential oil with trans-pinocamphone as a main component (37.9%). Phenolic compounds were identified using a combination of high performance liquid chromatography with diode array detection and electrospray ionization mass-spectrometric detection (HPLC-DAD-ESI-MS) techniques, as well as free carbohydrates and water soluble polysaccharides. For the first time, it was established that the cold acclimation of D. palmatum seedlings resulted in various changes in physiological and biochemical parameters such as membrane permeability, photosynthetic potential, membrane fluidity, leaf surface secretory function, reactive oxygen species–antioxidant balance, osmoregulator content and cell wall polymers. In brief, results showed that the adaptive strategy of D. palmatum under LT was realized on the accumulation of membrane or surface components with more fluid properties (unsaturated FA and essential oils), antioxidants (phenolic compounds and enzymes), osmoprotectants (free sugars) and cell wall components (polysaccharides). In addition, the occurrence of unusual flavonoids including two new isomeric malonyl esters of eriodictyol-7-O-glucoside was found in LT samples. Data thus obtained allow improving our understanding of ecophysiological mechanisms of cold adaptation of arctic plants.

Advances in transcriptome-based analyses of cold response and signaling pathways of plants

Low temperature is one of the most important environmental factors limiting plant growth, development, and distribution. Moreover, cold stress can always lead to impaired growth, mal-development, or even physiological imbalance in plants. On the brighter side, plants have evolved a number of adaptive mechanisms to resist cold depending upon the activation of molecular networks involved in stress perception, signal transcription and transduction, expression of specific stress-related genes, and physiological reaction of tolerance. Research related to plant cold response performed over the last few years has made significant achievements in the molecular, physiology, and phenology aspects. Genome-wide analyses have dramatically improved the efficiency of gene discovery. With the development of omics-based technology, including transcriptome and protein mass spectrometry, large-scale transcriptome data has become available in both model and non-model species. This paper uses transcriptome-based analyses of cold response and signaling pathways in Lilium lancifolium as an example, in combination with the latest studies in other plants, focusing on the molecular aspects of cold stress adaptive mechanisms. It attempts to highlight the major findings in response to cold stress factors from transcriptome-based analyses, and provides a tentative signaling regulatory pathway.

Expression of Candidate Cold Stress and Metabolic Related Genes in <i>Acidithiobacillus ferrivorans</i> PQ33 Strain Using Ferrous Iron as Electron Donor

The identification of genes involved in cold adaptations of psychrotolerant bacteria Acidithiobacillus ferrivorans is important for biomining processes that take place at low temperatures like Andean mining installations in Peru. We have performed relative quantification RT-qPCR on candidate genes to have a role in adaptations at low temperature (5°C). The candidate genes analyzed were six: Two trehalose synthesis pathway genes, trehalose synthase (treS) and malto-oligosiltrehalose trehalohydrolase (treZ) showing no overexpression at 5°C. Two diguanylate cyclases genes related to exopolymer synthesis and biofilm formation (designated as dgc-I and dgc-II in this paper) were overexpressed at 21°C. The rusA and rusB genes involved in iron oxidation showed no significant change for rusA and no expression for rusB gene in any of both conditions. Genes rpoC, gyrB and alaS were validated as reference genes. These results show congruency with trancriptomics studies about gene expression of A. ferrivorans. Furthermore, the trehalose synthesis genes show no overexpression at low temperatures suggesting that other cold adaptation mechanisms are involved.

Особенности апоптоза, индуцированного снижением температуры

We summarised and analysed here the findings on apoptosis contribution into the cell damages, caused by temperature deviation from the physiological norm (below 37°C). The participation of the caspases, causing the disintegration of anti-apoptotic Bcl- 2 family proteins and proteolysis of the DNAase inhibitor, responsible for DNA fragmentation in the apoptosis, induced by a moderate cell cooling, was shown. An important role in cold adaptation mechanism belongs to the RNA-binding protein (cold-inducible RNAbinding protein, CIRP), which is capable to prevent the oxidative stress-induced apoptosis development. We reported here the data, confirming the participation of reactive oxygen species and antioxidant cell components: superoxide dismutase and human peroxiredoxin 1 in apoptosis and cold adaptation. Probl Cryobiol Cryomed 2017; 27(2): 97–109

Ecology of cold environments: new insights of bacterial metabolic adaptation through an integrated genomic-phenomic approach

Cold environments dominate Earth’s biosphere, hosting complex microbial communities with the ability to thrive at low temperatures. However, the underlying molecular mechanisms and the metabolic pathways involved in bacterial cold-adaptation mechanisms are still not fully understood. Herein, we assessed the metabolic features of the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 (PhTAC125), a model organism for cold-adaptation, at both 4 °C and 15 °C, by integrating genomic and phenomic (high-throughput phenotyping) data and comparing the obtained results to the taxonomically related Antarctic bacterium Pseudoalteromonas sp. TB41 (PspTB41). Although the genome size of PspTB41 is considerably larger than PhTAC125, the higher number of genes did not reflect any higher metabolic versatility at 4 °C as compared to PhTAC125. Remarkably, protein S-thiolation regulated by glutathione and glutathionylspermidine appeared to be a new possible mechanism for cold adaptation in PhTAC125. More in general, this study represents an example of how ‘multi-omic’ information might potentially contribute in filling the gap between genotypic and phenotypic features related to cold-adaptation mechanisms in bacteria.

Cold adaptation of the Antarctic haloarchaea Halohasta litchfieldiae and Halorubrum lacusprofundi.

Halohasta litchfieldiae represents ∼ 44% and Halorubrum lacusprofundi ∼ 10% of the hypersaline, perennially cold (≥ -20°C) Deep Lake community in Antarctica. We used proteomics and microscopy to define physiological responses of these haloarchaea to growth at high (30°C) and low (10 and 4°C) temperatures. The proteomic data indicate that both species responded to low temperature by modifying their cell envelope including protein N-glycosylation, maintaining osmotic balance and translation initiation, and modifying RNA turnover and tRNA modification. Distinctions between the two species included DNA protection and repair strategies (e.g. roles of UspA and Rad50), and metabolism of glycerol and pyruvate. For Hrr. lacusprofundi, low temperature led to the formation of polyhydroxyalkanoate-like granules, with granule formation occurring by an unknown mechanism. Hrr. lacusprofundi also formed biofilms and synthesized high levels of Hsp20 chaperones. Hht. litchfieldiae was characterized by an active CRISPR system, and elevated levels of the core gene expression machinery, which contrasted markedly to the decreased levels of Hrr. lacusprofundi. These findings greatly expand the understanding of cellular mechanisms of cold adaptation in psychrophilic archaea, and provide insight into how Hht. litchfieldiae gains dominance in Deep Lake.

A Proteomic Perspective on the Bacterial Adaptation to Cold: Integrating OMICs Data of the Psychrotrophic Bacterium Exiguobacterium antarcticum B7.

Since the publication of one of the first studies using 2D gel electrophoresis by Patrick H. O’Farrell in 1975, several other studies have used that method to evaluate cellular responses to different physicochemical variations. In environmental microbiology, bacterial adaptation to cold environments is a “hot topic” because of its application in biotechnological processes. As in other fields, gel-based and gel-free proteomic methods have been used to determine the molecular mechanisms of adaptation to cold of several psychrotrophic and psychrophilic bacterial species. In this review, we aim to describe and discuss these main molecular mechanisms of cold adaptation, referencing proteomic studies that have made significant contributions to our current knowledge in the area. Furthermore, we use Exiguobacterium antarcticum B7 as a model organism to present the importance of integrating genomic, transcriptomic, and proteomic data. This species has been isolated in Antarctica and previously studied at all three omic levels. The integration of these data permitted more robust conclusions about the mechanisms of bacterial adaptation to cold.

Differential expression patterns of two delta-9-acyl-CoA desaturases in Thitarodes pui (Lepidoptera: Hepialidae) during different seasons and cold exposure.

Thitarodes pui larvae have a limited distribution in the Tibetan Plateau and are the host of a parasitic fungus, Ophiocordyceps sinensis. Low temperature is a main environmental stress. However, understanding of T. pui cold adaptation mechanisms is insufficient. Delta‐9‐acyl‐CoA desaturase (D9D) is closely correlated with cold adaptation for many organisms. To further understand the cold adaptation processes in T. pui larvae, two D9Ds, TpdesatA and TpdesatB were sequenced, and expression patterns were investigated during different seasons and cold exposure (under 0°C) in the laboratory. The full lengths of two cDNAs are 1,290 bp and 1,603 bp, and the ORFs encode a polypeptide of 348 and 359 amino acids, respectively. Four transmembrane domains, three conserved histidine residues and five hydrophobic regions exist in these two sequences. The expression level of TpdesatA is up‐regulated in the long‐term cold exposure and negatively correlated with temperature in seasonal patterns. TpdesatB responds to cold temperature in short‐term cold exposure and positively corresponds temporarily in seasonal expression. Two D9Ds may have different substrate specificities, TpdesatA tends to use C16:0 and C18:0 as substrate while TpdesatB prefers C18:0. In conclusion, TpdesatA may play a very important role in T. pui cold tolerance and TpdesatB regulates function in short‐term cold exposure and content change of fatty acids in the body.

Structural insights into the cold adaptation of the photosynthetic pigment-protein C-phycocyanin from an Arctic cyanobacterium

The cold adaptation mechanism of phycobiliproteins, the major photosynthetic pigment-proteins in cyanobacteria and red algae, has rarely been studied. Here we reported the biochemical, structural, and molecular dynamics simulation study of the C-phycocyanin from Arctic cyanobacterial strain Pseudanabaena sp. LW0831. We characterized the phycobilisome components of LW0831 and obtained their gene sequences. Compared to the mesophilic counterpart from Arthrospira platensis (Ar-C-PC), LW0831 C-phycocyanin (Ps-C-PC) has a decreased thermostability (∆Tm of −16°C), one of the typical features of cold-adapted enzymes. To uncover its structural basis, we resolved the crystal structure of Ps-C-PC 1 at 2.04Å. Consistent with the decrease in thermostability, comparative structural analyses revealed decreased intra-trimer and inter-trimer interactions in Ps-C-PC 1, compared to Ar-C-PC. However, comparative molecular dynamics simulations indicated that Ps-C-PC 1 shows similar flexibilities to Ar-C-PC for both the (αβ)3 trimer and (αβ)6 hexamer. Therefore, the optimization mode is clearly different from cold-adapted enzymes, which usually have increased flexibilities. Detailed analyses demonstrated different optimization modes for the α and β subunits and it was revealed that hydrophobic interactions are key to this difference, though salt bridges, hydrogen bonds, and surface hydrophobicity are also involved. This study is the first report of the structure of cold-adapted phycobiliproteins and provides insights into the cold-adaptation strategies of non-enzyme proteins.

Genomic, Transcriptomic, and Proteomic Analysis Provide Insights Into the Cold Adaptation Mechanism of the Obligate Psychrophilic Fungus Mrakia psychrophila.

Mrakia psychrophila is an obligate psychrophilic fungus. The cold adaptation mechanism of psychrophilic fungi remains unknown. Comparative genomics analysis indicated that M. psychrophila had a specific codon usage preference, especially for codons of Gly and Arg and its major facilitator superfamily (MFS) transporter gene family was expanded. Transcriptomic analysis revealed that genes involved in ribosome and energy metabolism were upregulated at 4°, while genes involved in unfolded protein binding, protein processing in the endoplasmic reticulum, proteasome, spliceosome, and mRNA surveillance were upregulated at 20°. In addition, genes related to unfolded protein binding were alternatively spliced. Consistent with other psychrophiles, desaturase and glycerol 3-phosphate dehydrogenase, which are involved in biosynthesis of unsaturated fatty acid and glycerol respectively, were upregulated at 4°. Cold adaptation of M. psychrophila is mediated by synthesizing unsaturated fatty acids to maintain membrane fluidity and accumulating glycerol as a cryoprotectant. The proteomic analysis indicated that the correlations between the dynamic patterns between transcript level changes and protein level changes for some pathways were positive at 4°, but negative at 20°. The death of M. psychrophila above 20° might be caused by an unfolded protein response.

Cold adaptation regulated by cryptic prophage excision in Shewanella oneidensis.

Among the environmental stresses experienced by bacteria, temperature shifts are one of the most important. In this study, we discovered a novel cold adaptation mechanism in Shewanella oneidensis that occurs at the DNA level and is regulated by cryptic prophage excision. Previous studies on bacterial cold tolerance mainly focus on the structural change of cell membrane and changes at the RNA and protein levels. Whether or not genomic change can also contribute to this process has not been explored. Here we employed a whole-genome deep-sequencing method to probe the changes at DNA level in a model psychrotrophic bacteria strain. We found that temperature downshift induced a 10 000-fold increase of the excision of a novel P4-like cryptic prophage. Importantly, although prophage excision only occurred in a relatively small population of bacteria, it was able to facilitate biofilm formation and promote the survival of the entire population. This prophage excision affected cell physiology by disrupting a critical gene encoding transfer-messenger RNA (tmRNA). In addition, we found that the histone-like nucleoid-structuring protein (H-NS) could silence prophage excision via binding to the promoter of the putative excisionase gene at warm temperatures. H-NS level was reduced at cold temperatures, leading to de-repression of prophage excision. Collectively, our results reveal that cryptic prophage excision acts as a regulatory switch to enable the survival of the host at low temperature by controlling the activity of tmRNA and biofilm formation.

Genomic mechanisms for cold tolerance and production of exopolysaccharides in the Arctic cyanobacterium Phormidesmis priestleyi BC1401.

BackgroundCyanobacteria are major primary producers in extreme cold ecosystems. Many lineages of cyanobacteria thrive in these harsh environments, but it is not fully understood how they survive in these conditions and whether they have evolved specific mechanisms of cold adaptation. Phormidesmis priestleyi is a cyanobacterium found throughout the cold biosphere (Arctic, Antarctic and alpine habitats). Genome sequencing of P. priestleyi BC1401, an isolate from a cryoconite hole on the Greenland Ice Sheet, has allowed for the examination of genes involved in cold shock response and production of extracellular polymeric substances (EPS). EPSs likely enable cyanobacteria to buffer the effects of extreme cold and by identifying mechanisms for EPS production in P. priestleyi BC1401 this study lays the way for investigating transcription and regulation of EPS production in an ecologically important cold tolerant cyanobacterium.ResultsWe sequenced the draft genome of P. priestleyi BC1401 and implemented a new de Bruijn graph visualisation approach combined with BLAST analysis to separate cyanobacterial contigs from a simple metagenome generated from non-axenic cultures. Comparison of known cold adaptation genes in P. priestleyi BC1401 with three relatives from other environments revealed no clear differences between lineages. Genes involved in EPS biosynthesis were identified from the Wzy- and ABC-dependent pathways. The numbers of genes involved in cell wall and membrane biogenesis in P. priestleyi BC1401 were typical relative to the genome size. A gene cluster implicated in biofilm formation was found homologous to the Wps system, although the intracellular signalling pathways by which this could be regulated remain unclear.ConclusionsResults show that the genomic characteristics and complement of known cold shock genes in P. priestleyi BC1401 are comparable to related lineages from a wide variety of habitats, although as yet uncharacterised cold shock genes in this organism may still exist. EPS production by P. priestleyi BC1401 likely contributes to its ability to survive efficiently in cold environments, yet this mechanism is widely distributed throughout the cyanobacterial phylum. Discovering how these EPS related mechanisms are regulated may help explain why P. priestleyi BC1401 is so successful in cold environments where related lineages are not.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2846-4) contains supplementary material, which is available to authorized users.

Development of a versatile method for targeted gene deletion and insertion by using the pyrF gene in the psychrotrophic bacterium, Shewanella livingstonensis Ac10

Shewanella livingstonensis Ac10, a psychrotrophic bacterium isolated from Antarctic seawater, grows well at low temperatures close to 0°C. The bacterium is useful as a host in a low-temperature protein expression system. It is also useful as a model microorganism to investigate the mechanisms of microbial cold-adaptation. Versatile genetic manipulation techniques would be useful to investigate the biology of this bacterium and to develop its applications. In this study, we developed a method for targeted gene deletion and insertion by using the gene coding for orotidine-5'-phosphate decarboxylase (pyrF), which is involved in pyrimidine synthesis. We found that S.livingstonensis Ac10 is sensitive to 5-fluoroorotic acid (5-FOA), which is converted to a highly toxic compound by the product of pyrF. A uracil-auxotrophic strain resistant to 5-FOA was constructed by deleting pyrF, thus allowing the use of a plasmid-borne copy of pyrF for selection of recombinants. We constructed the pyrF complementation suicide plasmid pKKP, which contains pyrF, the R6K replication origin, the mob site of RP4, an antibiotic marker gene, and a multiple cloning site. To demonstrate pyrF-based gene replacement, we deleted the internal region of orf5, the gene coding for an eicosapentaenoic acid (EPA) synthesis enzyme. We also successfully inserted a His6-tag-coding sequence into orf8, the gene coding for another EPA synthesis enzyme. This system allows the markerless deletion and insertion of desired sequences at specific sites in the genome, which remarkably facilitates genetic manipulation of this bacterium.

Complete genome sequence of the cold-active bacteriophage VMY22 from Bacillus cereus.

The cold-active bacteriophage VMY22, belonging to the Podoviridae family, was isolated from Mingyong Glacier in China. Sequence analysis revealed that the genome is 18,609bp long, with an overall G+C content of 36.4mol%, and 25 open reading frames (ORFs). The sequence contains 46 potential promoters, 6 transcription terminators, and no tRNAs. Most of the ORFs show a high degree of similarity to B103 (NC_004165). Two noteworthy findings were made. First, one of the predicted proteins, ORF 19, shows high sequence similarity to the bacteriocin biosynthesis protein from Bacillus cereus. From this information, we propose that the VMY22 phage is at an intermediate phase in its coevolution with its bacterial host. Second, seven of the hypothetical proteins appear to be unique to this cold-active B. cereus phage (i.e., not found in temperate-active B. cereus phages). These observations add to our current knowledge about the coevolution of bacteriophages and their hosts. The identification of a novel group of gene and protein structures and functions will lead to a better understanding of cold-adaptation mechanisms in bacteria and their bacteriophages.

Quantitative Proteomic Analysis Provides Novel Insights into Cold Stress Responses in Petunia Seedlings.

Low temperature is a major adverse environmental factor that impairs petunia growth and development. To better understand the molecular mechanisms of cold stress adaptation of petunia plants, a quantitative proteomic analysis using iTRAQ technology was performed to detect the effects of cold stress on protein expression profiles in petunia seedlings which had been subjected to 2°C for 5 days. Of the 2430 proteins whose levels were quantitated, a total of 117 proteins were discovered to be differentially expressed under low temperature stress in comparison to unstressed controls. As an initial study, 44 proteins including well known and novel cold-responsive proteins were successfully annotated. By integrating the results of two independent Gene Ontology (GO) enrichment analyses, seven common GO terms were found of which “oxidation-reduction process” was the most notable for the cold-responsive proteins. By using the subcellular localization tool Plant-mPLoc predictor, as much as 40.2% of the cold-responsive protein group was found to be located within chloroplasts, suggesting that the chloroplast proteome is particularly affected by cold stress. Gene expression analyses of 11 cold-responsive proteins by real time PCR demonstrated that the mRNA levels were not strongly correlated with the respective protein levels. Further activity assay of anti-oxidative enzymes showed different alterations in cold treated petunia seedlings. Our investigation has highlighted the role of antioxidation mechanisms and also epigenetic factors in the regulation of cold stress responses. Our work has provided novel insights into the plant response to cold stress and should facilitate further studies regarding the molecular mechanisms which determine how plant cells cope with environmental perturbation. The data have been deposited to the ProteomeXchange with identifier PXD002189.

The effect of temperature adaptation on the ubiquitin-proteasome pathway in notothenioid fishes.

There is an accumulating body of evidence suggesting that the sub-zero Antarctic marine environment places physiological constraints on protein homeostasis. Levels of ubiquitin (Ub)-conjugated proteins, 20S proteasome activity and mRNA expression of many proteins involved in both the Ub tagging of damaged proteins as well as the different complexes of the 26S proteasome were measured to examine whether there is thermal compensation of the Ub-proteasome pathway in Antarctic fishes to better understand the efficiency of the protein degradation machinery in polar species. Both Antarctic (Trematomus bernacchii, Pagothenia borchgrevinki) and non-Antarctic (Notothenia angustata, Bovichtus variegatus) notothenioids were included in this study to investigate the mechanisms of cold adaptation of this pathway in polar species. Overall, there were significant differences in the levels of Ub-conjugated proteins between the Antarctic notothenioids and B. variegatus, with N. angustata possessing levels very similar to those of the Antarctic fishes. Proteasome activity in the gills of Antarctic fishes demonstrated a high degree of temperature compensation such that activity levels were similar to activities measured in their temperate relatives at ecologically relevant temperatures. A similar level of thermal compensation of proteasome activity was not present in the liver of two Antarctic fishes. Higher gill proteasome activity is likely due in part to higher cellular levels of proteins involved in the Ub-proteasome pathway, as evidenced by high mRNA expression of relevant genes. Reduced activity of the Ub-proteasome pathway does not appear to be the mechanism responsible for elevated levels of denatured proteins in Antarctic fishes, at least in the gills.