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The Mycobacterial growth inhibition assay (MGIA) is an ex-vivo assay used to measure the overall functional immune response elicited by infection or vaccination. In tuberculosis (TB) vaccine development, MGIA is a potentially important tool for preclinical evaluation of early-stage vaccine candidates to complement existing assays, and to potentially reduce the need for lengthy and costly pathogenic Mycobacterium tuberculosis (Mtb) animal challenge experiments. The conventional method of MGIA in mice entails directly infecting mixed cell cultures, most commonly splenocytes, from immunised mice with mycobacteria. However, this direct infection of mixed cell populations may yield unreliable results and lacks sufficient sensitivity to discriminate well between different vaccines due to the low number of mycobacteria-permissive cells. Here, we modified the assay by inclusion of mycobacteria-infected congenic murine macrophage cell lines as the target cells, and by measuring the total number of killed cells rather than the relative reduction between different groups. Thus, using splenocytes from Mycobacterium bovis BCG immunised mice, and J774 and MH-S (BALB/c background) or BL/6-M (C57Bl/6 background) macrophage cell lines, we demonstrated that the modified assay resulted in at least 26-fold greater mycobacterial killing per set quantity of splenocytes as compared to the conventional method. This increased sensitivity of measuring mycobacterial killing was confirmed using both the standard culture forming unit (CFU) assay and luminescence readings of luciferase-tagged virulent and avirulent mycobacteria. We propose that the modified MGIA can be used as a highly calibrated tool for quantitating the killing capacity of immune cells in preclinical evaluation of vaccine candidates for TB. [ABSTRACT FROM AUTHOR]

Dysregulated epigenetic states are a hallmark of cancer and often arise from genetic alterations in epigenetic regulators. This includes missense mutations in histones, which, together with associated DNA, form nucleosome core particles. However, the oncogenic mechanisms of most histone mutations are unknown. Here, we demonstrate that cancer-associated histone mutations at arginines in the histone H3 N-terminal tail disrupt repressive chromatin domains, alter gene regulation, and dysregulate differentiation. We find that histone H3R2C and R26C mutants reduce transcriptionally repressive H3K27me3. While H3K27me3 depletion in cells expressing these mutants is exclusively observed on the minor fraction of histone tails harboring the mutations, the same mutants recurrently disrupt broad H3K27me3 domains in the chromatin context, including near developmentally regulated promoters. H3K27me3 loss leads to de-repression of differentiation pathways, with concordant effects between H3R2 and H3R26 mutants despite different proximity to the PRC2 substrate, H3K27. Functionally, H3R26C-expressing mesenchymal progenitor cells and murine embryonic stem cell-derived teratomas demonstrate impaired differentiation. Collectively, these data show that cancer-associated H3 N-terminal arginine mutations reduce PRC2 activity and disrupt chromatin-dependent developmental functions, a cancer-relevant phenotype. Missense mutations in histones can drive oncogenesis and disrupt chromatin, but the associated mechanisms for many such mutations remain poorly understood. Here, the authors show that cancer-associated histone mutations at arginines in the H3 N-terminal tail disrupt repressive chromatin domains, alter gene expression, and in one case impair differentiation via reduction of PRC2 function. [ABSTRACT FROM AUTHOR]

Background and objectives: The practice of teleneurology provided an accessible and safe method of consultation during the COVID-19 pandemic. We aimed to describe the practice of teleneurology among Filipino neurologists and determine the factors affecting its adoption using the unified theory of acceptance and use of technology (UTAUT) model and its constructs, namely performance expectancy, effort expectancy, social influence, and facilitating conditions. Methods: This was a cross-sectional survey conducted online last October 2020 involving adult and pediatric neurologists in the Philippines. The internal consistency of the questionnaire adapted from UTAUT model was determined using Cronbach's alpha. We performed logistic regression analysis to determine which constructs of the UTAUT model were significant factors on the intent to practice teleneurology. Results: The study yielded a 28.8% response rate. Among the respondents (n1 = 147), 95.2% (n2 = 140) practiced teleneurology during the pandemic, and 77.6% (n1 = 147) planned to continue it after the pandemic. Teleneurology was mostly done on an outpatient basis on social media platforms via videoconferencing due to easier access for both end-users. The UTAUT model explained 80.9% (95% CI 0.76, 0.86a) of the total variation. Performance expectancy and facilitating conditions affect the intent to use teleneurology. Conclusions: Due to the limited resources and knowledge of its practice, infrastructural support and benefit awareness campaigns would be beneficial to increase its adoption, especially in developing countries. [ABSTRACT FROM AUTHOR]

Uptake of noble gases into heterogeneous geologic core samples was measured using a piezometric methodology. In addition to measuring accessible porosity—as with gas pycnometry—by monitoring the rate of pressure decay, this method can also be used to estimate the gas effective diffusivity in the sample. In contrast to previous applications of this method, where milligram quantities of fractured grains are characterized, here approximately kilogram core samples were left intact when tested. In doing so, a more representative sample of the heterogeneous field geology is provided. Additionally, alteration of the pore structure and connectivity during sample preparation is avoided. To scale the piezometric method from milligrams to kilograms, the system was designed to operate at medium vacuum (1 to 100 Pa) to restrict transport in pores less than approximately 60 µm to large Knudsen numbers. To test the system performance, two samples of interest were selected: a rhyolitic welded tuff from Blue Canyon Dome at the Energetic Materials Research and Testing Center and a zeolitized non-welded rhyolitic tuff from the Nevada National Security Site. Three noble gases were utilized in this test series; Argon and xenon as they are of direct interest to nuclear monitoring efforts and helium as it is a weakly adsorbing reference standard. Additionally, mercury intrusion porosimetry measurements were made on subsamples of the core to compare the observed porosity by the two methods and to discuss gas transport rates in the context of the measured pore distribution. Article Highlights: The piezometric method was extended to measure transport in intact geologic core samples between 800 and 1400 g. Transport in the pores spaces was restricted to Knudsen flow using medium vacuum, enabling a closed-form solution. Argon and xenon in a zeolitized tuff core exhibited significant adsorption and enhanced transport relative to helium. [ABSTRACT FROM AUTHOR]

Detection of radioxenon and radioargon produced by underground nuclear explosions is one of the primary methods by which the Comprehensive Nuclear-Test–Ban Treaty (CTBT) monitors for nuclear activities. However, transport of these noble gases to the surface via barometric pumping is a complex process relying on advective and diffusive processes in a fractured porous medium to bring detectable levels to the surface. To better understand this process, experimental measurements of noble gas and chemical surrogate diffusivity in relevant lithologies are necessary. However, measurement of noble gas diffusivity in tight or partially saturated porous media is challenging due to the transparent nature of noble gases, the lengthy diffusion times, and difficulty maintaining consistent water saturation. Here, the quasi-steady-state Ney–Armistead method is modified to accommodate continuous gas sampling via effusive flow to a mass spectrometer. An analytical solution accounting for the cumulative sampling losses and induced advective flow is then derived. Experimental results appear in good agreement with the proposed theory, suggesting the presence of retained groundwater reduces the effective diffusivity of the gas tracers by 10–1000 times. Furthermore, by using a mass spectrometer, the method described herein is applicable to a broad range of gas species and porous media. [ABSTRACT FROM AUTHOR]

Condensin is a multi-subunit protein complex that belongs to the family of structural maintenance of chromosomes (SMC) complexes. Condensins regulate chromosome structure in a wide range of processes including chromosome segregation, gene regulation, DNA repair and recombination. Recent research defined the structural features and molecular activities of condensins, but it is unclear how these activities are connected to the multitude of phenotypes and functions attributed to condensins. In this review, we briefly discuss the different molecular mechanisms by which condensins may regulate global chromosome compaction, organization of topologically associated domains, clustering of specific loci such as tRNA genes, rDNA segregation, and gene regulation. [ABSTRACT FROM AUTHOR]

Detection of radioxenon is a critical component of underground nuclear explosion monitoring. Sulfur hexafluoride (SF6) has historically served as a Xe tracer. This work explores the use of carbon tetrafluoride (CF4) as an alternative for field tests given its general suitability as a tracer and reduced greenhouse gas potential compared to SF6. Gas Chromatography-Mass Spectrometry measurements characterized the diffusive behavior of CF4 in a 2-bulb apparatus to determine how well int approximates Xe. The measured diffusion coefficient of SF6 was 78% of that of Xe, agreeing with literature values, while CF4 diffused at 97% the rate of Xe. [ABSTRACT FROM AUTHOR]

The pressing global issue of food insecurity due to population growth, diminishing land and variable climate can only be addressed in agriculture by improving both maximum crop yield potential and resilience. Genetic modification is one potential solution, but has yet to achieve worldwide acceptance, particularly for crops such as wheat. Trehalose-6-phosphate (T6P), a central sugar signal in plants, regulates sucrose use and allocation, underpinning crop growth and development. Here we show that application of a chemical intervention strategy directly modulates T6P levels in planta. Plant-permeable analogues of T6P were designed and constructed based on a 'signalling-precursor' concept for permeability, ready uptake and sunlight-triggered release of T6P in planta. We show that chemical intervention in a potent sugar signal increases grain yield, whereas application to vegetative tissue improves recovery and resurrection from drought. This technology offers a means to combine increases in yield with crop stress resilience. Given the generality of the T6P pathway in plants and other small-molecule signals in biology, these studies suggest that suitable synthetic exogenous small-molecule signal precursors can be used to directly enhance plant performance and perhaps other organism function. [ABSTRACT FROM AUTHOR]

X-linked recessive dystonia-parkinsonism is a rare movement disorder that is highly prevalent in Panay Island in the Philippines. Earlier studies identified seven different genetic alterations within a 427-kb disease locus on the X chromosome; however, the exact disease-causing variant among these is still not unequivocally determined. To further investigate the genetic cause of this disease, we sequenced all previously reported genetic alterations in 166 patients and 473 Filipino controls. Singly occurring variants in our ethnically matched controls would have allowed us to define these as polymorphisms, but none were found. Instead, we identified five patients carrying none of the disease-associated variants, and one male control carrying all of them. In parallel, we searched for novel single-nucleotide variants using next-generation sequencing. We did not identify any shared variants in coding regions of the X chromosome. However, by validating intergenic variants discovered via genome sequencing, we were able to define the boundaries of the disease-specific haplotype and narrow the disease locus to a 294-kb region that includes four known genes. Using microarray-based analyses, we ruled out the presence of disease-linked copy number variants within the implicated region. Finally, we utilized in silico analysis and detected no strong evidence of regulatory regions surrounding the disease-associated variants. In conclusion, our finding of disease-specific variants occurring in complete linkage disequilibrium raises new insights and intriguing questions about the origin of the disease haplotype, the existence of phenocopies and of reduced penetrance, and the causative genetic alteration in XDP. [ABSTRACT FROM AUTHOR]

Maize, the highest-yielding cereal crop worldwide, is particularly susceptible to drought during its 2- to 3-week flowering period. Many genetic engineering strategies for drought tolerance impinge on plant development, reduce maximum yield potential or do not translate from laboratory conditions to the field. We overexpressed a gene encoding a rice trehalose-6-phosphate phosphatase (TPP) in developing maize ears using a floral promoter. This reduced the concentration of trehalose-6-phosphate (T6P), a sugar signal that regulates growth and development, and increased the concentration of sucrose in ear spikelets. Overexpression of TPP increased both kernel set and harvest index. Field data at several sites and over multiple seasons showed that the engineered trait improved yields from 9% to 49% under non-drought or mild drought conditions, and from 31% to 123% under more severe drought conditions, relative to yields from nontransgenic controls. [ABSTRACT FROM AUTHOR]

The article discusses an inaugural meeting of the International Society for Plant Molecular Farming (ISPMF) held at the Julius Kuehn Institute in Berlin, Germany on June 17-19, 2014. Topics include immunology of plant derived recombinant proteins, genetically engineered plant viruses as vaccines, downstream processing, plant tissues culture and therapeutic use of plant derived recombinant proteins and.

Accumulation of reactive oxygen species (ROS) causes oxidative stress under adverse environmental conditions, such as salinity. Ethylene decreases accumulation of ROS induced by salinity, but the mechanism is still unclear. To examine the interactions between salinity and ROS accumulation and the possible role of ethylene metabolism in regulation, we used mutant ein2- 5 in Arabidopsis with loss of function in EIN2. The mutant is compared to the wild-type Col-0, completely insensitivity to ethylene at the morphological, physiological and molecular levels. The oxidative responses of the wild type and mutant to salinity were compared. Loss-of-function of EIN2 enhanced sensitivity to salinity, implying that EIN2 is required for plant response to salinity. Furthermore, salinity resulted in accumulation of large amounts of ROS in ein2- 5 seedlings when compared with Col-0, suggesting that the loss-of-function of EIN2 exaggerates oxidative stress induced by salinity. Activities of the antioxidant enzymes SOD, POD and CAT decreased significantly in ein2- 5 under salinity when compared with Col-0 plants. The expression profiles of the genes Fe- SOD, PODs and CAT1, which code for ROS scavenging enzymes were severely decreased in ein2- 5 under salinity compared with Col-0, suggesting that EIN2 was involved in regulating expression of these genes. Taken together, our results demonstrate that loss-of-function of EIN2 increased oxidative stress induced by salinity and that EIN2 is involved in modulating ROS accumulation, at least in part, by decreasing activities of ROS-scavenging enzymes. [ABSTRACT FROM AUTHOR]

We previously described the expression of a tumour-targeting antibody (mAb H10) in Nicotiana benthamiana by vacuum-agro-infiltration and the remarkable yields of highly pure protein achieved. The objective of the present work was to investigate different strategies for transient overexpression of the mAb H10 in which glycan configuration was modulated and assess how these strategies affect the accumulation yield and stability of the antibody. To this aim, three procedures have been assayed: (1) Site-directed mutagenesis to abolish the glycosylation site; (2) endoplasmic reticulum retention (C-terminal SEKDEL fusion) to ensure predominantly high-mannose type glycans; and (3) expression in a N. benthamiana RNAi down-regulated line in which β1,2- xylosyltransferase and α1,3- fucosyltransferase gene expression is silenced. The three antibody variants (H10-Mut) (H10-SEKDEL) (H10) were transiently expressed, purified and characterised for their glycosylation profile, expression/purification yield and antibody degradation pattern. Glycosylation analysis of H10 demonstrated the absence of plant complex-type sugars, while H10-SEKDEL, although substantially retained in the ER, revealed the presence of β1,2-xylose and α1,3-fucose residues, indicating a partial escape from the ER retrieval system. Antibody accumulation and purification yields were not enhanced by ER retention. All H10 antibody glyco-forms revealed greater degradation compared to the original, resulting mostly in the formation of Fab fragments. In the case of aglycosylated H10-Mut, more than 95% of the heavy chain was cleaved, confirming the pivotal role of the sugar moiety in protein stability. Identification of possible 'fragile' sites in the H10 antibody hinge region could be of general interest for the development of new strategies to reduce antibody degradation and increase the yield of intact IgGs in plants. [ABSTRACT FROM AUTHOR]

Application of multivariate statistics to trace element datasets is reviewed using 164 multi-element LA-ICP-MS spot analyses of pyrite from the Moonlight epithermal gold prospect, Queensland, Australia. Multivariate analysis of variance (MANOVA) is used to demonstrate that classification of pyrite on morphological and other non-numeric factors is geochemically valid. Parallel coordinate plots and correlation cluster analysis using Spearman's coefficients are used to discover unexpected elemental relationships without making assumptions a priori. Finally, principal component analysis and factor analysis are used to demonstrate the presence of sub-classes of pyrite. Corroborated with geological data, statistical analysis provides evidence for successive generations of hydrothermal fluids, each introducing specific metals, and for partial or complete replacement of different minerals. The data permit reinterpretation of Moonlight as a telescoped system where epithermal-Au (± base metals) is superposed onto early porphyry-Mo mineralization. [ABSTRACT FROM AUTHOR]

Nicotiana tabacum is emerging as a crop of choice for production of recombinant protein pharmaceuticals. Although there is significant commercial expertise in tobacco farming, different cultivation practices are likely to be needed when the objective is to optimise protein expression, yield and extraction, rather than the traditional focus on biomass and alkaloid production. Moreover, pharmaceutical transgenic tobacco plants are likely to be grown initially within a controlled environment, the parameters for which have yet to be established. Here, the growth characteristics and functional recombinant protein yields for two separate transgenic tobacco plant lines were investigated. The impacts of temperature, day-length, compost nitrogen content, radiation and plant density were examined. Temperature was the only environmental variable to affect IgG concentration in the plants, with higher yields observed in plants grown at lower temperature. In contrast, temperature, supplementary radiation and plant density all affected the total soluble protein yield in the same plants. Transgenic plants expressing a second recombinant protein (cyanovirin-N) responded differently to IgG transgenic plants to elevated temperature, with an increase in cyanovirin-N concentration, although the effect of the environmental variables on total soluble protein yields was the same as the IgG plants. Planting density and radiation levels were important factors affecting variability of the two recombinant protein yields in transgenic plants. Phenotypic differences were observed between the two transgenic plant lines and non-transformed N. tabacum, but the effect of different growing conditions was consistent between the three lines. Temperature, day length, radiation intensity and planting density all had a significant impact on biomass production. Taken together, the data suggest that recombinant protein yield is not affected substantially by environmental factors other than growth temperature. Overall productivity is therefore correlated to biomass production, although other factors such as purification burden, extractability protein stability and quality also need to be considered in the optimal design of cultivation conditions. [ABSTRACT FROM AUTHOR]

Affective responses to objects can be influenced by cognitive processes such as perceptual fluency. Here we investigated whether the quality of motor interaction with an object influences affective response to the object. Participants grasped and moved objects using either a fluent action or a non-fluent action (avoiding an obstacle). Liking ratings were higher for objects in the fluent condition. Two further studies investigated whether the fluency of another person’s actions influences affective response. Observers watched movie clips of the motor actions described above, in conditions where the observed actor could be seen to be looking towards the grasped object, or where the actor’s head and gaze were not visible. Two results were observed: First, when the actor’s gaze cannot be seen, liking ratings of the objects are reduced. Second, action fluency of observed actions does influence liking ratings, but only when the actor’s gaze towards the object is visible. These findings provide supporting evidence for the important role of observed eye gaze in action simulation, and demonstrate that non-emotive actions can evoke empathic states in observers. [ABSTRACT FROM AUTHOR]

We have previously obtained several lines of tobacco transformed with a trehalose-6-phosphate synthase gene of plant origin ( Arabidopsis thaliana), involved in the first step of the biosynthesis of trehalose, a known osmoprotectant. Two showed distinct intensity of expression: high (B5H) and low (B1F). Such lines were analyzed for trehalose-6-phosphate content and the obtained results demonstrated to be in accordance with the expression results. In order to study the responses of photosynthesis to water deficit of transgenic lines in comparison to wild type (WT), three experiments were performed under different conditions: (1) Relative water (2) Leaf gas exchange (3) Modulated Chlorophyll a Fluorescence. Different responses in RWC of plant lines to water withdrawal were detected, with transgenic line B5H indicating less water loss after the water withdrawal period. Similar responses to water deficit regarding the leaf gas exchanges were recorded for the three lines. When subjected to water deficit stress situations, higher F v/ F m, ΦPSII and qP were detected for the transgenic lines. Under a SWC of 20% where higher values for such parameters were detected with special relevance for the B5H line, indicating a possible higher ability to withstand severe drought stress and to resist to prolonged periods without water than the B1F and WT lines. [ABSTRACT FROM AUTHOR]

DNA homologous to the yeast (Saccharomyces cerevisiae) protein kinase gene, GCN2, was amplified from arabidopsis [Arabidopsis thaliana (L.) Heynh.] RNA and given the name AtGCN2. The AtGCN2 peptide sequence included adjacent protein kinase and histidyl tRNA synthetase-like domains and showed 45% sequence identity with the GCN2 peptide sequence in the protein kinase domain. AtGCN2 transcripts were detectable in RNA from roots, leaves, stems, buds, flowers, siliques and seedlings. GCN2 is required for yeast cells to respond to amino acid starvation. Expression of AtGCN2 in yeast gcn2 mutants complemented the mutation, enabling growth in the presence of sulfometuron methyl, an inhibitor of branched-chain amino acid biosynthesis, and 3-aminotriazole, an inhibitor of histidine biosynthesis. [ABSTRACT FROM AUTHOR]

Previous work has shown that in a sequential cueing task, inhibition of the return of attention (IOR) can be observed for up to four or five loci. We have argued that the inhibition processes mediating IOR are associated with object-based representations, and it is object-based representations that are maintained in memory. Experiments presented here show that, compared with standard conditions in which a number of identical grey squares are cued, cueing empty locations tends to reduce the memory for prior inhibitory processes; while cueing objects which are distinctive in colour and shape tends to increase memory for inhibition. Converging with other recent findings, we conclude that memory for the inhibitory processes of attention facilitates visual search and that this memory is dependent on object-based representations. [ABSTRACT FROM AUTHOR]

The pre-motor theory suggests that, when attention is oriented to a location, the motor systems that are involved in achieving current behavioural goals are activated. For example, when a task requires accurate reaching, attention to a location activates the motor circuits controlling saccades and manual reaches. These actions involve separate neural systems for the control of eye and hand, but we believe that the selection processes acting on neural population codes within these systems are similar and can affect each other. The attentional effect can be revealed in the subsequent movement. The present study shows that the path the eye takes as it saccades to a target is affected by whether a reach to the target is also produced. This effect is interpreted as the influence of a hand-centred frame used in reaching on the spatial frame of reference required for the saccade. [ABSTRACT FROM AUTHOR]

To test the hypothesis that the contribution of phosphoribulokinase (PRK) to the control of photosynthesis changes depending on the light environment of the plant, the response of transgenic tobacco (Nicotiana tabacum L.) transformed with antisense PRK constructs to irradiance was determined. In plants grown under low irradiance (330 μmol m-2 s-1) steady-state photosynthesis was limited in plants with decreased PRK activity upon exposure to higher irradiance, with a control coefficient of PRK for CO2 assimilation of 0.25 at and above 800 μmol m-2 s-1. The flux control coefficient of PRK for steady-state CO2 assimilation was zero, however, at all irradiances in plant material grown at 800 μmol m-2 s-1 and in plants grown in a glasshouse during mid-summer (alternating shade and sun 300–1600 μmol m-2 s-1). To explain these differences between plants grown under low and high irradiances, Calvin cycle enzyme activities and metabolite content were determined. Activities of PRK and other non-equilibrium Calvin cycle enzymes fructose-1,6-bisphosphatase, sedoheptulose-1,7-bisphosphatase and ribulose-1,5-bisphosphate carboxylase-oxygenase were twofold higher in plants grown at 800 μmol m-2 s-1 or in the glasshouse than in plants grown at 330 μmol m-2 s-1. Activities of equilibrium enzymes transketolase, aldolase, ribulose-5-phosphate epimerase and isomerase were very similar under all growth irradiances. The flux control coefficient of 0.25 in plants grown at 330 μmol m-2 s-1 can be explained because low ribulose-5-phosphate content in combination with low PRK activity limits the synthesis of ribulose-1,5-bisphosphate. This limitation is overcome in high-light-grown plants because of the large relative increase in activities of sedoheptulose-1,7-bisphosphatase and fructose-1,6-bisphosphatase under these conditions, which facilitates the synthesis of larger amounts of ribulose-5-phosphate. This potential limitation will have maintained evolutionary selection pressure for high concentrations of PRK within the chloroplast. [ABSTRACT FROM AUTHOR]

Tobacco plants ( Nicotiana tabacum L.) transformed with an inverted cDNA encoding ribulose 5-phosphate kinase (phosphoribulokinase,PRK; EC 2.7.1.19) were employed to study the in vivo relationship between photosynthetic electron transport and the partitioning of electron transport products to major carbon metabolism sinks under conditions of elevated ATP concentrations and limited ribulose 1,5-bisphosphate (RuBP) regeneration. Simultaneous measurements of room temperature chlorophyll fluorescence and CO gas exchange were conducted on intact leaves. Under ambient CO concentrations and light intensities above those at which the plants were grown, transformants with only 5% of PRK activity showed 'down-regulation' of PS II activity and electron transport in response to a decrease in net carbon assimilation when compared to wild-type. This was manifested as a decline in the efficiency of PS II electron transport (Φ), an increase in dissipation of excess absorbed light in the antennae of PS II and a decline in: total linear electron transport (J), electron transport dedicated to carbon assimilation (J) and electron transport allocated to photorespiration (J). The transformants showed no alteration in the Rubisco specificity factor measured in vitro and calculated in vivo but had a relatively smaller ratio of RuBP oxygenation to carboxylation rates (v/v), due to a higher CO concentration at the carboxylation site (C). The relationship between Φ and Φwas similar in transformants and wild-type under photorespiratory conditions demonstrating no change in the intrinsic relationship between PS II function and carbon assimilation, however, a novel result of this study is that this similar relationship occurred at different values of quantum flux, J, J, J and v/v in the transformant. For both wild-type and transformants, an assessment was made of the possible presence of a third major sink for electron transport products, beside RuBP oxygenation and carboxylation, the data provided no evidence for such a sink. [ABSTRACT FROM AUTHOR]

Spring wheat ( Triticum aestivum L.) was grown under optimal nutrition for six weeks at 700 and 350 μmol·mol CO and simultaneous measurements of photosystem-II (PSII) chlorophyll fluorescence and gas exchange were conducted on intact attached leaves. Plants grown at elevated CO had double the concentration of CO at the carboxylation site (C) despite a lowered stomatal (g) and mesophyll (g) conductance compared with ambient-grown plants. Plants grown at elevated CO had a higher relative quantum yield of PSII electron transport (Φ) and a higher relative quantum yield of CO fixation (Φ). The higher Φ was due to a larger proportion of open PSII centres, estimated by the coefficient of photochemical quenching of fluorescence (q), with no change in the efficiency of light harvesting and energy transduction by open PSII centres (F′/F′). Analysis of the relationship between Φ and Φ conducted under various CO and O concentrations showed that the higher Φ for a given Φ in leaves developed under elevated CO was similar to that obtained in leaves upon a partial reduction in photorespiration. Calculation of the allocation of photosynthetic electron-transport products to CO and O showed that for leaves developed in elevated CO, there was an increase in both total linear electron flow and electron flow to CO and a decrease in electron flow to O. Plants developed under elevated CO showed positive acclimation manifested by a higher Φ when measured under ambient CO and higher assimilation rates in A/C curves. Initial and total activity of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco EC 4.1.1.39) measured in vitro increased by 16 and 15% respectively in leaves from plants grown in elevated CO, which was in agreement with a 15% higher in vivo carboxylation efficiency. It is concluded that growth of spring wheat at elevated CO enhances photosynthesis due to a change in the balance of component processes manifested as an increased capacity for carbon fixation, total electron transport and Rubisco activity, and a concomitant partial reduction of photorespiration. [ABSTRACT FROM AUTHOR]

Transformation of tobacco with the potato gene encoding the subunit of pyrophosphate: fructose-6-phosphate 1-phosphotransferase (PFP) in the antisense orientation under the control of the constitutive CaMV 35S promoter, followed by selfing and crossing of the transformants, generated a line of tobacco (5-37) with up to an 85% reduction in PFP activity in the shoot. Transformants containing a sense construct (4-40-91) contained only 1-3% of wild-type PFP, presumably due to co-suppression. Rates of photosynthesis and partitioning between sucrose and starch in source leaves were identical in 4-40-91 transformants and the wild type. In the dark in sink leaves of 4-40-91 transformants, levels of hexose phosphates were up to 50% higher, glycerate-3-phosphate 30% lower and fructose-2,6-bisphosphate threefold higher than in the wild type; inorganic pyrophosphate, pyruvate and the ATP/ADP ratio were unaltered. Low -PFP and wild-type plants did not differ significantly in their rate of growth at 25° C and 200 μmol quanta · m · s on full nutrient medium. Growth on limiting phosphate and limiting nitrogen was inhibited identically in the wild type and transformants, and transformants adjusted their shoot/root ratio in an identical manner to the wild type. Differences in fructose-2,6-bisphosphate and glycolytic metabolites between the wild type and transformants were no larger in these suboptimal nutrient conditions, than in optimal conditions. Growth of the wild type and 4-40-91 transformants was inhibited identically at 12° C compared to 25° C. Differences in fructose-2,6-bisphosphate were smaller when the genotypes were compared at 12° C than at 25° C. We conclude that PFP does not play an essential role in photosynthate partitioning in source leaves. During respiratory metabolism in sink leaves it catalyzes a net glycolytic flux, as in potato tubers. However, tobacco seedlings are able to compensate for a large decrease in expression of PFP without loss of growth, or the ability to cope with suboptimal phosphate, nitrogen or temperature. [ABSTRACT FROM AUTHOR]

Post-translational modifications (PTMs) on histones are a key source of regulation on chromatin through impacting cellular processes, including gene expression 1 . These PTMs often arise from metabolites and are thus impacted by metabolism and environmental cues 2-7 . One class of metabolically regulated PTMs are histone acylations, which include histone acetylation, butyrylation, crotonylation and propionylation 3,8 . As these PTMs can be derived from short-chain fatty acids, which are generated by the commensal microbiota in the intestinal lumen 9-11 , we aimed to define how microbes impact the host intestinal chromatin landscape, mainly in female mice. Here we show that in addition to acetylation, intestinal epithelial cells from the caecum and distal mouse intestine also harbour high levels of butyrylation and propionylation on lysines 9 and 27 of histone H3. We demonstrate that these acylations are regulated by the microbiota and that histone butyrylation is additionally regulated by the metabolite tributyrin. Tributyrin-regulated gene programmes are correlated with histone butyrylation, which is associated with active gene-regulatory elements and levels of gene expression. Together, our study uncovers a regulatory layer of how the microbiota and metabolites influence the intestinal epithelium through chromatin, demonstrating a physiological setting in which histone acylations are dynamically regulated and associated with gene regulation., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)