Arabidopsis HEAT SHOCK TRANSCRIPTION FACTORA1b regulates multiple developmental genes under benign and stress conditions

In Arabidopsis thaliana, HEAT SHOCK TRANSCRIPTION FACTORA1b (HSFA1b) controls resistance to environmental stress and is a determinant of reproductive fitness by influencing seed yield. To understand how HSFA1b achieves this, we surveyed its genome-wide targets (ChIP-seq) and its impact on the transcriptome (RNA-seq) under nonstress (NS), heat stress (HS) in te wild type, and in HSFA1b-overexpressing plants under NS. A total of 952 differentially expressed HSFA1b-targeted genes were identified, of which at least 85 are development associated and were bound predominantly under NS. A further 1780 genes were differentially expressed but not bound by HSFA1b, of which 281 were classified as having development-associated functions. These genes are indirectly regulated through a hierarchical network of 27 transcription factors (TFs). Furthermore, we identified 480 natural antisense non-coding RNA (cisNAT) genes bound by HSFA1b, defining a further mode of indirect regulation. Finally, HSFA1b-targeted genomic features not only harboured heat shock elements, but also MADS box, LEAFY, and G-Box promoter motifs. This revealed that HSFA1b is one of eight TFs that target a common group of stress defence and developmental genes. We propose that HSFA1b transduces environmental cues to many stress tolerance and developmental genes to allow plants to adjust their growth and development continually in a varying environment

Development of pGEMINI, a Plant Gateway Destination Vector Allowing the Simultaneous Integration of Two cDNA via a Single LR-Clonase Reaction

Gateway technology has been used to facilitate the generation of a large number of constructs for the modification of plants for research purposes. However, many of the currently available vectors only allow the integration of a single cDNA of interest into an expression clone. The ability to over-express multiple genes in combination is essential for the study of plant development where several transcripts have a role to play in one or more metabolic processes. The tools to carry out such studies are limited, and in many cases rely on the incorporation of cDNA into expression systems via conventional cloning, which can be both time consuming and laborious. To our knowledge, this study reports on the first development of a vector allowing the simultaneous integration of two independent cDNAs via a single LR-clonase reaction. This vector “pGEMINI” represents a powerful molecular tool offering the ability to study the role of multi-cDNA constructs on plant development, and opens up the process of gene stacking and the study of gene combinations through transient or stable transformation procedures

The effects of upper and lower limb exercise on the microvascular reactivity in limited cutaneous systemic sclerosis patients

Background: Aerobic exercise in general and high intensity interval training (HIIT) specifically is known to improve vascular function in a range of clinical conditions. HIIT in particular has demonstrated improvements in clinical outcomes, in conditions that have a strong macroangiopathic component. Nevertheless, the effect of HIIT on microcirculation in systemic sclerosis (SSc) patients is yet to be investigated. Therefore, the purpose of the study was to compare the effects of two HIIT protocols (cycle and arm cranking) on the microcirculation of the digital area in SSc patients. Methods: Thirty four limited cutaneous SSc patients (65.3 ± 11.6 years old) were randomly allocated in three groups (cycling, arm cranking and control group). The exercise groups underwent a twelve-week exercise program twice per week. All patients performed the baseline and post-exercise intervention measurements where physical fitness, functional ability, transcutaneous oxygen tension (ΔtcpO2), body composition and quality of life were assessed. Endothelial-dependent as well as-independent vasodilation were assessed in the middle and index fingers using LDF and incremental doses of acetylcholine (ACh) and sodium nitroprusside (SNP). Cutaneous flux data were expressed as cutaneous vascular conductance (CVC). Results: Peak oxygen uptake increased in both exercise groups (p<0.01, d=1.36). ΔtcpO2 demonstrated an increase in the arm cranking group only, with a large effect, but not found statistically significant,(p=0.59, d=0.93). Endothelial-dependent vasodilation improvement was greater in the arm cranking (p<0.05, d=1.07) in comparison to other groups. Both exercise groups improved life satisfaction (p<0.001) as well as reduced discomfort and pain due to Raynaud's phenomenon (p<0.05). Arm cranking seems to be the preferred mode of exercise for study participants as compared to cycling (p<0.05). No changes were observed in the body composition or the functional ability in both exercise groups. Conclusion: Our results suggest that arm cranking has the potential to improve the microvascular endothelial function in SSc patients. Also notably, our recommended training dose (e.g., a 12-week HIIT program, twice per week), appeared to be sufficient and tolerable for this population. Future research should focus on exploring the feasibility of a combined exercise such as aerobic and resistance training by assessing individual's experience and the quality of life in SSc patients. Trial registration: ClinicalTrials.gov (NCT number): NCT03058887, February 23, 2017, https://clinicaltrials.gov/ct2/show/NCT03058887?term=NCT03058887&rank=1 Key words: High intensity interval training, vascular function, quality of lif

Panmixia in a fragmented and unstable environment: the hydrothermal shrimp Rimicaris exoculata disperses extensively along the Mid-Atlantic ridge

Dispersal plays a fundamental role in the evolution and persistence of species, and especially for species inhabiting extreme, ephemeral and highly fragmented habitats as hydrothermal vents. The Mid-Atlantic Ridge endemic shrimp species Rimicaris exoculata was studied using microsatellite markers to infer connectivity along the 7100-Km range encompassing the sampled sites. Astonishingly, no genetic differentiation was found between individuals from the different geographic origins, supporting a scenario of widespread large-scale dispersal despite the habitat distance and fragmentation. We hypothesize that delayed metamorphosis associated to temperature differences or even active directed migration dependent on physical and/or chemical stimuli could explain these results and warrant further studies on adaptation and dispersal mechanisms

The Cyst-Dividing Bacterium Ramlibacter tataouinensis TTB310 Genome Reveals a Well-Stocked Toolbox for Adaptation to a Desert Environment

Ramlibacter tataouinensis TTB310T (strain TTB310), a betaproteobacterium isolated from a semi-arid region of South Tunisia (Tataouine), is characterized by the presence of both spherical and rod-shaped cells in pure culture. Cell division of strain TTB310 occurs by the binary fission of spherical “cyst-like” cells (“cyst-cyst” division). The rod-shaped cells formed at the periphery of a colony (consisting mainly of cysts) are highly motile and colonize a new environment, where they form a new colony by reversion to cyst-like cells. This unique cell cycle of strain TTB310, with desiccation tolerant cyst-like cells capable of division and desiccation sensitive motile rods capable of dissemination, appears to be a novel adaptation for life in a hot and dry desert environment. In order to gain insights into strain TTB310's underlying genetic repertoire and possible mechanisms responsible for its unusual lifestyle, the genome of strain TTB310 was completely sequenced and subsequently annotated. The complete genome consists of a single circular chromosome of 4,070,194 bp with an average G+C content of 70.0%, the highest among the Betaproteobacteria sequenced to date, with total of 3,899 predicted coding sequences covering 92% of the genome. We found that strain TTB310 has developed a highly complex network of two-component systems, which may utilize responses to light and perhaps a rudimentary circadian hourglass to anticipate water availability at the dew time in the middle/end of the desert winter nights and thus direct the growth window to cyclic water availability times. Other interesting features of the strain TTB310 genome that appear to be important for desiccation tolerance, including intermediary metabolism compounds such as trehalose or polyhydroxyalkanoate, and signal transduction pathways, are presented and discussed

Measuring redox changes in vivo in leaves: Prospects and technical challenges

In leaves, the functioning of many key proteins under conditions promoting oxidative stress depends to a large extent on the redox potential of the glutathione couple. Routine measurements of the glutathione pool in leaves are destructive and labor-intensive processes that tend to underestimate the redox state. Therefore, a challenge for plant scientists is to develop a tool capable of measuring the redox state of the glutathione couple spatially (at different levels of resolution) and temporally in tissues and subcellular compartments in vivo. This chapter highlights the possibilities of using redox-sensitive green fluorescence proteins (roGFPs) as real-time redox reporters for use in intact plants and focuses on practical assessments of using such bioindicators in different leaf cell types subjected to environmental change. The advantages and shortcomings of different GFP variants are discussed along with the choice of system for leaves and possible approaches to overcoming some of the problems. We consider roGFP1-12 as an ideal candidate for developing a redox reporter system in whole plants because it has several advantages over the other variants, with dual excitation peaks allowing a ratiometric approach, insensitivity to pH and halide ions, increased response times for real-time measurements, and appropriate emission wavelengths for use in leaves. We conclude that when using roGFP1-12 with specific cell promotors, it would be possible to target distinct cell compartments and tissues and monitor changes in glutathione redox state to determine the effects of reactive oxygen species on specific cellular components. © 2008 Humana Press, a part of Springer Science+Business Media, LLC

The Use of HyPer to Examine Spatial and Temporal Changes in H₂O₂ in High Light-Exposed Plants

Exposure of photosynthetic cells of leaf tissues of Arabidopsis thaliana (Arabidopsis) to high light intensities (HL) may provoke a rapid rise in hydrogen peroxide (H₂O₂ ) levels in chloroplasts and subcellular compartments, such as peroxisomes, associated with photosynthetic metabolism. It has been hypothesized that when H₂O₂ is contained at or near its site of production then it plays an important role in signaling to induce acclimation to HL. However, should this discrete containment fail and H₂O₂ levels exceed the capacity of antioxidant systems to scavenge them, then oxidative stress ensues which triggers cell death. To test this hypothesis, the spatiotemporal accumulation of H₂O₂ needs to be quantified in different subcellular compartments. In this chapter, preliminary experiments are presented on the use of Arabidopsis seedlings transformed with a nuclear-encoded cytosol-located yellow fluorescent protein-based sensor for H₂O₂ , called HyPer. HyPer allows ratiometric determination of its fluorescence at two excitation wavelengths, which frees quantification of H₂O₂ from the variable levels of HyPer in vivo. HyPer fluorescence was shown to have the potential to provide the necessary spatial, temporal, and quantitative resolution to study HL responses of seedlings using confocal microscopy. Chlorophyll fluorescence imaging was used to quantify photoinhibition of photosynthesis induced by HL treatment of seedlings on the microscope staging. However, several technical issues remain, the most challenging of which is the silencing of HyPer expression beyond the seedling stage. This limited our pilot studies to cotyledon epidermal cells, which while not photosynthetic, nevertheless responded to HL with 45% increase in cytosolic H₂O₂