Gene expression and genetic mapping analyses of a perennial ryegrass glycine-rich RNA-binding protein gene suggest a role in cold adaptation

A perennial ryegrass cDNA clone encoding a putative glycine-rich RNA binding protein (LpGRP1) was isolated from a cDNA library constructed from crown tissues of cold-treated plants. The deduced polypeptide sequence consists of 107 amino acids with a single N-terminal RNA recognition motif (RRM) and a single C-terminal glycine-rich domain. The sequence showed extensive homology to glycine-rich RNA binding proteins previously identified in other plant species. LpGRP1-specific genomic DNA sequence was isolated by an inverse PCR amplification. A single intron which shows conserved locations in plant genes was detected between the sequence motifs encoding RNP-1 and RNP-2 consensus protein domains. A significant increase in the mRNA level of LpGRP1 was detected in root, crown and leaf tissues during the treatment of plants at 4°C, through which freezing tolerance is attained. The increase in the mRNA level was prominent at least 2 h after the commencement of the cold treatment, and persisted for at least 1 week. Changes in mRNA level induced by cold treatment were more obvious than those due to treatments with abscisic acid (ABA) and drought. The LpGRP1 protein was found to localise in the nucleus in onion epidermal cells, suggesting that it may be involved in pre-mRNA processing. The LpGRP1 gene locus was mapped to linkage group 2. Possible roles for the LpGRP1 protein in adaptation to cold environments are discussed.     

Combining gene expression and genetic analyses to identify candidate genes involved in cold responses in pea

Cold stress affects plant growth and development. In order to better understand the responses to cold (chilling or freezing tolerance), we used two contrasted pea lines. Following a chilling period, the Champagne line becomes tolerant to frost whereas the Terese line remains sensitive.     

Developmental control of stress stimulons in Streptomyces coelicolor revealed by statistical analyses of global gene expression patterns

Stress-induced regulatory networks coordinated with a procaryotic developmental program were revealed by two-dimensional gel analyses of global gene expression. Four developmental stages were identified by their distinctive protein synthesis patterns using principal component analysis. Statistical analyses focused on five stress stimulons (induced by heat, cold, salt, ethanol, or antibiotic shock) and their synthesis during development. Unlike other bacteria, for which various stresses induce expression of similar sets of protein spots, in Streptomyces coelicolor heat, salt, and ethanol stimulons were composed of independent sets of proteins. This suggested independent control by different physiological stress signals and their corresponding regulatory systems. These stress proteins were also under developmental control. Cluster analysis of stress protein synthesis profiles identified 10 different developmental patterns or "synexpression groups." Proteins induced by cold, heat, or salt shock were enriched in three developmental synexpression groups. In addition, certain proteins belonging to the heat and salt shock stimulons were coregulated during development. Thus, stress regulatory systems controlling these stimulons were implicated as integral parts of the developmental program. This correlation suggested that thermal shock and salt shock stress response regulatory systems either allow the cell to adapt to stresses associated with development or directly control the developmental program.     

Genetics of gene expression responses to temperature stress in a sea urchin gene network

Stress responses play an important role in shaping species distributions and robustness to climate change. We investigated how stress responses alter the contribution of additive genetic variation to gene expression during development of the purple sea urchin, Strongylocentrotus purpuratus, under increased temperatures that model realistic climate change scenarios. We first measured gene expression responses in the embryos by RNA‐seq to characterize molecular signatures of mild, chronic temperature stress in an unbiased manner. We found that an increase from 12 to 18 °C caused widespread alterations in gene expression including in genes involved in protein folding, RNA processing and development. To understand the quantitative genetic architecture of this response, we then focused on a well‐characterized gene network involved in endomesoderm and ectoderm specification. Using a breeding design with wild‐caught individuals, we measured genetic and gene–environment interaction effects on 72 genes within this network. We found genetic or maternal effects in 33 of these genes and that the genetic effects were correlated in the network. Fourteen network genes also responded to higher temperatures, but we found no significant genotype–environment interactions in any of the genes. This absence may be owing to an effective buffering of the temperature perturbations within the network. In support of this hypothesis, perturbations to regulatory genes did not affect the expression of the genes that they regulate. Together, these results provide novel insights into the relationship between environmental change and developmental evolution and suggest that climate change may not expose large amounts of cryptic genetic variation to selection in this species.     

低温胁迫下6种木兰科植物的生理响应及抗寒相关基因差异表达

分析了6种木兰科植物对低温胁迫的生理响应及耐寒相关调控基因HSP90和WRKY33的差异表达,为木兰科植物抗寒机理的研究和抗寒品种的选育提供理论基础。结果表明,6种木兰科植物的低温LT50在-10.64—-22.06℃,从高到低依次为红花深山含笑、峨眉含笑、杂交含笑、阔瓣含笑、六瓣含笑和乐东拟单性木兰;低温过程中,6种木兰科植物叶片可溶性蛋白(SP)、游离脯氨酸(Pro)含量、超氧化物歧化酶(SOD)和过氧化物歧化酶(POD)活性呈先升高后降低的趋势,可溶性糖(SS)和丙二醛含量(MDA)则不断积累;筛选出REC、MDA、SP、SS和Pro作为6种木兰科植物抗寒性评价的关键指标;聚类分析将6种木兰科植物在抗寒性能上分为强、中、弱三类,分别为乐东拟单性木兰和六瓣含笑,阔瓣含笑、杂交含笑和峨眉含笑,以及红花深山含笑。对HSP90、WRKY33基因的差异表达分析表明,2个基因在6种木兰科植物中的相对表达量呈先升高后降低的趋势,在临近各树种LT 50时,2个基因的表达被强烈抑制且后期表达量不可逆。0℃时,2个基因的表达量差异不显著;-5℃时,2个基因开始被激活,表达量增加;-10℃时,HSP90、WRKY33基因在红花深山含笑叶片中的表达量较-5℃时分别下调了0.76倍和0.68倍,而在其他5个树种中的表达被进一步激活;-15℃时,HSP90和WRKY33基因在抗寒性中等的阔瓣含笑、杂交含笑、峨眉含笑中亦被强烈抑制,较-10℃时分别下调了0.38倍、0.33倍、0.32倍和0.71倍、0.72倍、0.74倍,在抗寒性强的乐东拟单性木兰和六瓣含笑中的表达被进一步激活;-20℃以后,2个基因在6个树种中的表达均被强烈抑制,但在抗寒性最强的乐东拟单性木兰中的表达量仍高于其他5个树种。抗寒基因的激活与表达是影响植物抗寒性的重要因素,抗寒性不同的树种对低温的应答机制明显不同。抗寒性越强的树种越能快速启动低温应答机制,激活抗寒相关基因的表达,进而调整生理生化活动以抵御和适应冷应力。不抗寒树种中抗寒基因的表达则受到抑制,降低了其对低温逆境的耐受能力。     

Comparative analyses reveal potential uses of Brachypodium distachyon as a model for cold stress responses in temperate grasses

ABSTRACT: BACKGROUND: Little is known about the potential of Brachypodium distachyon as a model for low temperature stress responses in Pooideae. The ice recrystallization inhibition proteins (IRIP) genes, fructosyltransferase (FST) genes, and many C-repeat binding factor (CBF) genes are Pooideae specific and important in low temperature responses. Here we use comparative analyses to study conservation and evolution of these gene families in B. distachyon to better understand B. distachyon's potential as a model species for agriculturally important temperate grasses RESULTS: Brachypodium distachyon contains cold responsive IRIP genes which have evolved through Brachypodium specific gene family expansions. A large cold responsive CBF3 subfamily was identified in B. distachyon, while CBF4 homologs are absent from the genome. No B. distachyon FST gene homologs encode typical core Pooideae FST-motifs and low temperature induced fructan accumulation was dramatically different in B. distachyon compared to core Pooideae species. CONCLUSIONS: We conclude that B. distachyon can serve as an interesting model for specific molecular mechanisms involved in low temperature responses in core Pooideae species. However, the evolutionary history of key genes involved in low temperature responses has been different in Brachypodium and core Pooideae species. These differences limit the use of B. distachyon as a model for holistic studies relevant for agricultural core Pooideae species.     

An overlap between osmotic and anaerobic stress responses: a potential role for DNA supercoiling in the coordinate regulation of gene expression

The regulation of several genes in response to osmotic and anaerobic stress has been examined. We have demonstrated a clear overlap between these two regulatory signals. Thus, the osmotically induced proU and ompC genes require anaerobic growth for optimum induction while the anaerobically induced tppB gene is also regulated by osmolarity. Furthermore, normal expression of tppB and ompC requires the positive regulatory protein OmpR, yet this requirement can be partially, or even fully, overcome by altering the growth conditions. Finally, the pleiotropic, anaerobic regulatory locus, oxrC, is also shown to affect expression of the osmotically regulated proU gene. The oxrC mutation is shown to affect the level of negative supercoiling of plasmid DNA and its effects on gene expression can be explained as secondary consequences of altered DNA topology. We suggest that there is a class of 'stress-regulated' genes that are regulated by a common mechanism in response to different environmental signals. Furthermore, our data are consistent with the notion that this regulatory overlap is mediated by changes in DNA supercoiling in response to these environmental stresses.     

IL-8 and global gene expression analysis define a key role of ATP in renal epithelial cell responses induced by uropathogenic bacteria

The recent recognition of receptor-mediated ATP signalling as a pathway of epithelial pro-inflammatory cytokine release challenges the ubiquitous role of the TLR4 pathway during urinary tract infection. The aim of this study was to compare cellular responses of renal epithelial cells infected with uropathogenic Escherichia coli (UPEC) strain IA2 to stimulation with ATP-γ-S. A498 cells were infected or stimulated in the presence or absence of apyrase, that degrades extracellular ATP, or after siRNA-mediated knockdown of ATP-responding P2Y₂ receptors. Cellular IL-8 release and global gene expression were analysed. Both IA2 and A498 cells per se released ATP, which increased during infection. IA2 and ATP-γ-S caused a ∼5-fold increase in cellular release of IL-8 and stimulations performed in the presence of apyrase or after siRNA knockdown of P2Y₂ receptors resulted in attenuation of IA2-mediated IL-8 release. Microarray results show that both IA2 and ATP-γ-S induced marked changes in gene expression of renal cells. Thirty-six genes were in common between both stimuli, and many of these are key genes belonging to classical response pathways of bacterial infection. Functional analysis shows that 88 biological function-annotated cellular pathways were identical between IA2 and ATP-γ-S stimuli. Results show that UPEC-induced release of IL-8 is dependent on P2Y₂ signalling and that cellular responses elicited by UPEC and ATP-γ-S have many identical features. This indicates that renal epithelial responses elicited by bacteria could be mediated by bacteria- or host-derived ATP, thus defining a key role of ATP during infection.

Electronic supplementary material

The online version of this article (doi:10.1007/s11302-014-9414-7) contains supplementary material, which is available to authorized users.     

Invited review: Effects of heat and cold stress on mammalian gene expression.

This review examines the effects of thermal stress on gene expression, with special emphasis on changes in the expression of genes other than heat shock proteins (HSPs). There are approximately 50 genes not traditionally considered to be HSPs that have been shown, by conventional techniques, to change expression as a result of heat stress, and there are <20 genes (including HSPs) that have been shown to be affected by cold. These numbers will likely become much larger as gene chip array and proteomic technologies are applied to the study of the cell stress response. Several mechanisms have been identified by which gene expression may be altered by heat and cold stress. The similarities and differences between the cellular responses to heat and cold may yield key insights into how cells, and by extension tissues and organisms, survive and adapt to stress.     

The osnR gene of Corynebacterium glutamicum plays a negative regulatory role in oxidative stress responses

Journal of Industrial Microbiology & Biotechnology - Among the Corynebacterium glutamicum ORFs that have been implicated in stress responses, we chose ORF cg3230, designated osnR, and analyzed...