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Plants can perceive a slight upsurge in ambient temperature and respond by undergoing morphological changes, such as elongated hypocotyls and early flowering. The dynamic functioning of PHYTOCHROME INTERACTING FACTOR4 (PIF4) in thermomorphogenesis is well established, although the complete regulatory pathway involved in thermosensing remains elusive. We establish that an increase in temperature from 22˚C to 28˚C induces upregulation and activation of MITOGEN-ACTIVATED PROTEIN KINASE 4 (MPK4) in Arabidopsis (Arabidopsis thaliana), subsequently leading to the phosphorylation of PIF4. Phosphorylated PIF4 represses the expression of ACTIN-RELATED PROTEIN 6 (ARP6), which is required for mediating the deposition of histone variant H2A.Z at its target loci. Furthermore, we demonstrate that variations in ARP6 expression in PIF4 phosphor-null and phosphor-mimetic seedlings affect hypocotyl growth at 22˚C and 28˚C by modulating the regulation of ARP6-mediated H2A.Z deposition at the loci of genes involved in elongating hypocotyl cells. Interestingly, the expression of MPK4 is also controlled by H2A.Z deposition in a temperature-dependent manner. Taken together, these findings highlight the regulatory mechanism of thermosensing by which MPK4-mediated phosphorylation of PIF4 affects ARP6-mediated H2A.Z deposition at the genes involved in hypocotyl cell elongation., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Phosphate (Pi) deficiency leads to the induction of purple acid phosphatases (PAPs) in plants, which dephosphorylate organic phosphorus (P) complexes in the rhizosphere and intracellular compartments to release Pi. In this study, we demonstrate that OsPAP3b belongs to group III low-molecular weight PAP and is low Pi-responsive, preferentially in roots. The expression of OsPAP3b is negatively regulated with Pi resupply. Interestingly, OsPAP3b was found to be dual localized to the nucleus and secretome. Furthermore, OsPAP3b is transcriptionally regulated by OsPHR2 as substantiated by DNA-protein binding assay. Through in vitro biochemical assays, we further demonstrate that OsPAP3b is a functional acid phosphatase (APase) with broad substrate specificity. The overexpression (OE) of OsPAP3b in rice led to increased secreted APase activity and improved mineralization of organic P sources, which resulted in better growth of transgenics compared to the wild type when grown on organic P as an exogenous P substrate. Under Pi deprivation, OsPAP3b knock-down and knock-out lines showed no significant changes in total P content and dry biomass. However, the expression of other phosphate starvation-induced genes and the levels of metabolites were found to be altered in the OE and knock-down lines. In addition, in vitro pull-down assay revealed multiple putative interacting proteins of OsPAP3b. Our data collectively suggest that OsPAP3b can aid in organic P utilization in rice. The APase isoform behavior and nuclear localization indicate its additional role, possibly in stress signaling. Considering its important roles, OsPAP3b could be a potential target for improving low Pi adaptation in rice., (© The Author(s) 2023. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

It is well established that DNA double-strand break (DSB) repair is required to underpin chromosomal DNA replication. Because DNA replication forks are prone to breakage, faithful DSB repair and correct replication fork restart are critically important. Cells, where the proteins required for DSB repair are absent or altered, display characteristic disturbances to genome replication. In this review, we analyze how bacterial DNA replication is perturbed in DSB repair mutant strains and explore the consequences of these perturbations for bacterial chromosome segregation and cell viability. Importantly, we look at how DNA replication and DSB repair processes are implicated in the striking recent observations of DNA amplification and DNA loss in the chromosome terminus of various mutant Escherichia coli strains. We also address the mutant conditions required for the remarkable ability to copy the entire E. coli genome, and to maintain cell viability, even in the absence of replication initiation from oriC, the unique origin of DNA replication in wild type cells. Furthermore, we discuss the models that have been proposed to explain these phenomena and assess how these models fit with the observed data, provide new insights and enhance our understanding of chromosomal replication and termination in bacteria., (© FEMS 2020.)

Objective: Mutations in the aryl hydrocarbon receptor-interacting protein ( AIP ) gene are associated with pituitary adenoma, acromegaly and gigantism. Identical alleles in unrelated pedigrees could be inherited from a common ancestor or result from recurrent mutation events., Design and Methods: Observational, inferential and experimental study, including: AIP mutation testing; reconstruction of 14 AIP -region (8.3 Mbp) haplotypes; coalescent-based approximate Bayesian estimation of the time to most recent common ancestor (tMRCA) of the derived allele; forward population simulations to estimate current number of allele carriers; proposal of mutation mechanism; protein structure predictions; co-immunoprecipitation and cycloheximide chase experiments., Results: Nine European-origin, unrelated c.805_825dup-positive pedigrees (four familial, five sporadic from the UK, USA and France) included 16 affected (nine gigantism/four acromegaly/two non-functioning pituitary adenoma patients and one prospectively diagnosed acromegaly patient) and nine unaffected carriers. All pedigrees shared a 2.79 Mbp haploblock around AIP with additional haploblocks privately shared between subsets of the pedigrees, indicating the existence of an evolutionarily recent common ancestor, the 'English founder', with an estimated median tMRCA of 47 generations (corresponding to 1175 years) with a confidence interval (9-113 generations, equivalent to 225-2825 years). The mutation occurred in a small tandem repeat region predisposed to slipped strand mispairing. The resulting seven amino-acid duplication disrupts interaction with HSP90 and leads to a marked reduction in protein stability., Conclusions: The c.805_825dup allele, originating from a common ancestor, associates with a severe clinical phenotype and a high frequency of gigantism. The mutation is likely to be the result of slipped strand mispairing and affects protein-protein interactions and AIP protein stability., (© 2017 The authors.)

Mitogen-activated protein kinase (MAPK) signal transduction networks have been extensively explored in plants; however, the connection between MAPK signaling cascades and submergence tolerance is currently unknown. The ethylene response factor-like protein SUB1A orchestrates a plethora of responses during submergence stress tolerance in rice (Oryza sativa). In this study, we report that MPK3 is activated by submergence in a SUB1A-dependent manner. MPK3 physically interacts with and phosphorylates SUB1A in a tolerant-allele-specific manner. Furthermore, the tolerant allele SUB1A1 binds to the MPK3 promoter and regulates its expression in a positive regulatory loop during submergence stress signaling. We present molecular and physiological evidence for the key role of the MPK3-SUB1A1 module in acclimation of rice seedlings to the adverse effects of submergence. Overall, the results provide a mechanistic understanding of submergence tolerance in rice., (© 2016 American Society of Plant Biologists. All rights reserved.)

MicroRNAs (miRNAs), the small non-coding RNAs, have been implicated in various biological processes including adaptation during environmental stress. The present work explores the involvement of miRNA during arsenic (As) and selenium (Se) treatment in rice seedlings. Arsenic is a heavy metalloid causing severe adverse effects on the growth and development of plants while Se is another metalloid and an essential micro-nutrient when present in appropriate amounts. It was observed that the presence of Se along with As mitigated the adverse effects of As on seedling germination, root-shoot growth, total chlorophyll and protein contents. The measurement of stress indicators such as proline, cysteine and MDA also indicated similar effects. Analysis of the miRNA profile using microarrays under As, Se and As + Se treatments showed differential regulation of at least 46 miRNAs in rice seedlings compared to untreated control. 18 of these miRNAs showed differential regulation among different treatments. Furthermore the microarray data were validated using real time PCR. The target genes of a few of these miRNAs showed inverse transcript accumulation. The possible role of miR395 and miR398 in the antagonistic effect on the adverse response of As in the presence of Se in rice seedlings is discussed.

Mitogen-activated protein kinase (MAPK) pathways are involved in several signal transduction processes in eukaryotes. Light signal transduction pathways have been extensively studied in plants; however, the connection between MAPK and light signaling pathways is currently unknown. Here, we show that MKK3-MPK6 is activated by blue light in a MYC2-dependent manner. MPK6 physically interacts with and phosphorylates a basic helix-loop-helix transcription factor, MYC2, and is phosphorylated by a MAPK kinase, MKK3. Furthermore, MYC2 binds to the MPK6 promoter and regulates its expression in a feedback regulatory mechanism in blue light signaling. We present mutational and physiological studies that illustrate the function of the MKK3-MPK6-MYC2 module in Arabidopsis thaliana seedling development and provide a revised mechanistic view of photomorphogenesis., (© 2014 American Society of Plant Biologists. All rights reserved.)

Background: The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is most accurate for estimating glomerular filtration rate (GFR) but requires an adjustment for African-American patients. Estimation equations are also improved with the use of serum cystatin C combined with standardized creatinine. Combination equations have been derived by the CKD-EPI and Chinese investigators. We investigated whether these cystatin C-based equations improve estimation adequately, so that adjustments for ethnicity are not required in a multiethnic Asian population with chronic kidney disease (CKD)., Methods: This was a cross-sectional study of 232 stable CKD patients who underwent GFR measurements using 3-sample plasma clearances of (99m)Tc-DTPA, and for whom serum cystatin C and creatinine were quantified., Results: For all patients, the median biases with cystatin C equations were generally greater than with the CKD-EPI equation, and precision and root mean square error (RMSE) were not significantly better. However, the combination serum creatinine and cystatin C equation improved the precision, RMSE, and percentage of estimated GFR to within 15% and 30% of the measured GFR (57.3% vs 50.0%, 88.4% vs 82.8%, respectively). The derived ethnicity coefficients for the combination equation were all >1 (1.009-1.082) but small, suggesting that coefficients are not required. The Chinese-specific equations were more biased and performed more poorly than the CKD-EPI equation., Conclusions: The use of a cystatin C and creatinine combination equation for estimating GFR in a multiethnic Asian population with CKD does not require ethnicity coefficients because the derived coefficients are very close to each other.

Mitogen-Activated Protein Kinase Kinase Kinases (MAPKKKs) are important components of MAPK cascades, which are universal signal transduction modules and play important role in plant growth and development. In the sequenced Arabidopsis genome 80 MAPKKKs were identified and currently being analysed for its role in different stress. In rice, economically important monocot cereal crop only five MAPKKKs were identified so far. In this study using computational analysis of sequenced rice genome we have identified 75 MAPKKKs. EST hits and full-length cDNA sequences (from KOME or Genbank database) of 75 MAPKKKs supported their existence. Phylogenetic analyses of MAPKKKs from rice and Arabidopsis have classified them into three subgroups, which include Raf, ZIK and MEKK. Conserved motifs in the deduced amino acid sequences of rice MAPKKKs strongly supported their identity as members of Raf, ZIK and MEKK subfamilies. Further expression analysis of the MAPKKKs in MPSS database revealed that their transcripts were differentially regulated in various stress and tissue-specific libraries.

Phytopathogen infection leads to changes in secondary metabolism based on the induction of defence programmes as well as to changes in primary metabolism which affect growth and development of the plant. Therefore, pathogen attack causes crop yield losses even in interactions which do not end up with disease or death of the plant. While the regulation of defence responses has been intensively studied for decades, less is known about the effects of pathogen infection on primary metabolism. Recently, interest in this research area has been growing, and aspects of photosynthesis, assimilate partitioning, and source-sink regulation in different types of plant-pathogen interactions have been investigated. Similarly, phytopathological studies take into consideration the physiological status of the infected tissues to elucidate the fine-tuned infection mechanisms. The aim of this review is to give a summary of recent advances in the mutual interrelation between primary metabolism and pathogen infection, as well as to indicate current developments in non-invasive techniques and important strategies of combining modern molecular and physiological techniques with phytopathology for future investigations.

A preparation of Tinospora cordifolia (RTc) administered i.p. (200 mg/kg b.w.) to strain "A" male mice 1 h before whole body gamma-irradiation was evaluated for its radioprotective efficacy in terms of whole body survival, spleen colony forming units (CFU), hematological parameters, cell cycle progression, and micronuclei induction. Preirradiation treatment with RTc rendered 76.3% survival (30 days), compared to 100% mortality in irradiated control and prevented radiation induced weight loss. On 10th postirradiation day, the endogenous CFU counts in spleen were decreased with increasing radiation doses 12.0 (5 Gy), 2.16 (7.5 Gy) and 0.33 (10 Gy) but pre-irradiation administration of 200 mg/kg b.w. of RTc increased CFU counts to 31.16, 21.83 and 3.00 respectively. Pre-irradiation RTc treatment could restore total lymphocyte counts (TLC) by the 15th day to normal. It also increased the S-phase cell population that was reduced following 2 Gy irradiation in a time dependent manner. 2 Gy irradiation-induced micronuclei were also decreased by a pre-irradiation administration of RTc from 2.9 to 0.52%. Because the radioprotective manifestation of RTc observed in several systems in experimental animals can be exploited for human applications.

Extracellular invertase is the key enzyme of an apoplasmic phloem unloading pathway and catalyses the hydrolytic cleavage of the transport sugar sucrose released into the apoplast. This mechanism contributes to long-distance assimilate transport, provides the substrate to sustain heterotrophic growth and generates metabolic signals known to effect various processes of primary metabolism and defence responses. The essential function of extracellular invertase for supplying carbohydrates to sink organs was demonstrated by the finding that antisense repression of an anther-specific isoenzyme provides an efficient method for metabolic engineering of male sterility. The regulation of extracellular invertase by all classes of phytohormones indicates an essential link between the molecular mechanism of phytohormone action and primary metabolism. The up-regulation of extracellular invertase appears to be a common response to various biotic and abiotic stress-related stimuli such as pathogen infection and salt stress, in addition to specific stress-related reactions. Based on the observed co-ordinated regulation of source/sink relations and defence responses by sugars and stress-related stimuli, the identified activation of distinct subsets of MAP kinases provides a mechanism for signal integration and distribution within such complex networks. Sucrose derivatives not synthesized by higher plants, such as turanose, were shown to elicit responses distinctly different from metabolizable sugars and are rather perceived as stress-related stimuli.

Escherichia coli heat-stable enterotoxin (STa) was found to bind on the surface of human colonic (COLO 205) cells. The binding of [125I]STa to cell membranes was found to be specific, reversible and saturable. Scatchard analysis of the equilibrium binding demonstrated a single class of binding sites with a Kd of 0.5 x 10(-10) M. Autoradiographic analysis of polyacrylamide gel electrophoresis revealed the specific incorporation of [125I]STa into a single STa binding protein with a molecular mass of 95 kDa. Following incubation of COLO 205 cells with STa, a rise of intracellular cGMP was also evident.

Kanagawa positive strains of Vibrio parahaemolyticus showed adherence whereas most of the Kanagawa negative strains were non-adhering to rabbit intestinal epithelial cells. Anti-hemolysin antisera did not inhibit the adherence of V. parahaemolyticus strains. Moreover, the adhesive capacity of non-adhering strains was not enhanced by purified hemolysin. Cell surface hydrophobicity remained the same in both Kanagawa positive and negative strains of V. parahaemolyticus. Fetuin strongly inhibited the adherence to rabbit intestinal epithelial cells followed by -mannose and D-glucose.

The central nervous system depends on thyroid hormones (TH) in regard to its development, maturation, and maintenance of normal functions. As there is much evidence to suggest that the effects of TH are mainly mediated through specific nuclear binding sites, we have studied the anatomical distribution of T3 nuclear receptors in different regions of adult rat brain, and the localization of receptors in the fractionated neuronal and glial nuclei of neocortex, paleocortex, and cerebellum. Purified nuclei from the various brain regions were prepared by ultracentrifugation in 2.2 M sucrose. Purified neuronal and glial fractions were obtained by discontinuous sucrose gradient centrifugation in 2.2 and 2.4 M sucrose. The washed nuclear fractions were used for T3 binding assay at 37 C for 30 min and the data analyzed by least squares nonlinear regression analysis. Nonfractionated nuclei from all regions studied were found to have similar dissociation constant (Kd) values (1.04-1.38 nM) and Eadie-Hofstee plots indicated the presence of an apparently ubiquitous single class of high affinity, low capacity binding sites. The increase in binding from cerebellum (54 +/- 24 fmol/mg DNA; mean +/- SE) to neocortex (666 +/- 89 fmol/mg DNA) showed a caudo-cranial pattern. In fractionated neuronal nuclei, the same trend was observed, only to a greater degree (1628 +/- 266, 994 +/- 76 and 212 +/- 29 fmol/mg DNA in neocortex, paleocortex, and cerebellum, respectively); the difference between corresponding values for glial nuclei of neocortex and paleocortex (357 +/- 139 and 250 +/- 92 fmol/mg DNA, respectively) was not statistically significant, and no specific T3 binding was found in cerebellar glial nuclei. These data suggest that TH may have an important role in neurons from phylogenetically newer regions, concerned with higher mental functions. The caudo-rostral distribution pattern may also indicate a gradient of TH actions in central nervous system regions.

Previous studies have shown that nuclear thyroid hormone receptors in rat brain are preferentially localized within neurons. These cells also synthesize protein at a high rate, and the aim of the present study was to investigate any relationship between these two characteristics. In this paper we have shown that T3 stimulates leucine uptake and incorporation into protein in primary cell cultures of neurons. Stimulation was apparent with concentrations of hormone as low as 1.25 nM and increased in a dose-dependent manner up to 10 nM T3. However, the rapidity of the effect (evident at 25 min, and significant at 40 min) suggests that protein synthesis is stimulated at the level of translation, rather than transcription. More detailed study with 5 nM T3, revealed that incorporation into both soluble (cytoplasmic) and insoluble (membrane-associated) protein fractions was stimulated to similar degrees, and therefore the effect on protein synthesis was general. Furthermore, T3-mediated stimulation of leucine uptake into neurons was completely abolished in the presence of the protein synthesis inhibitors, actinomycin D and cycloheximide, and therefore the effect on leucine uptake was attributed to an increased requirement for the amino acid in protein synthesis (pleiotrophic effect). Parallel studies conducted with synaptosomes and mitochondria isolated from the central nervous system of adult euthyroid animals revealed that 5 nM T3 was without effect on leucine uptake and incorporation into protein. Possible reasons for this lack of effect are discussed.

In order to investigate the localization of nuclear T3 receptors in adult rat brain, we have developed a technique for separating neuronal and glial nuclei, and compared nuclear T3 binding in both fractions. Glial and neuronal nuclear populations were prepared by homogenization of the whole brain except the cerebellum, followed by discontinuous density gradient centrifugation in 2.4 and 2.2 M sucrose. For purposes of comparison, liver nuclei were prepared by centrifugation in 2.4 M sucrose. Microscopic examination of the nuclei confirmed the purity of the two nuclear fractions to be above 90% with minimal extranuclear contamination. T3 binding studies were performed on the washed nuclear fractions using saturation analysis techniques. Maximum binding (Bmax) and dissociation constant (Kd) were obtained by nonlinear least-squares regression analysis. After 30 min incubation at 37 C, Bmax in neuronal nuclei was 1203 +/- 118 fmol/mg DNA (mean +/- SE) (n = 6), in comparison with 196 +/- 14 fmol/mg DNA in glial nuclei (n = 7). The corrected value for Bmax in glial nuclei, assuming 8% neuronal nuclear contamination, was 100 fmol/mg DNA. Bmax in liver nuclei was contamination, was 100 fmol/mg DNA. Bmax in liver nuclei was 299 +/- 38 fmol/mg DNA (n = 6). The Kd values were 0.38 +/- 0.04 nM, 0.34 +/- 0.05 nM, and 0.33 +/- 0.04 nM in neuronal, glial, and liver nuclei, respectively. The specificity of T3 binding to the nuclear receptor in both neuronal and glial nuclei was studied in competition studies, and revealed closely similar relative binding affinities (T3 greater than T4 greater than rT3) in both. We conclude that the higher T3 binding capacity of neuronal nuclei may be related to their higher protein synthetic ability, suggesting that T3 may be of importance in a rapid structural turnover in these cells. The effect of T3 on myelination in glial cells may be mediated through the nucleus.

In vitro cytogenetic assays are widely conducted to assess the mutagenic potential of chemicals. Chinese hamster ovary (CHO) cells or human lymphocytes are often used for these assays; however, these cell types have certain limitations. In order to evaluate an alternate cell system, cultured rat lymphocytes were treated for 4 h at 48 h of incubation with a variety of direct- and indirect-acting clastogens in the presence or absence of an exogenous mammalian activation system. Cytogenetic effects of in vitro physiological alterations such as medium hypertonicity or pH changes were also evaluated. The background aberration rate of rat lymphocytes is approximately 2%, and they respond positively to both direct- and indirect-acting clastogens. In contrast to CHO cells, however, neither the hyperosmolality nor pH changes in the treatment media have significant effect on background aberrations. Unlike samples of human blood, rat blood can be collected under well-controlled environmental conditions. Because of the easy access to rat blood samples, the simplicity of culture, the reproducible nature of its in vitro growth, the positive response to known clastogens and negative response to media pH changes or hyperosmolalities, the rat lymphocyte in vitro chromosomal assay presented is an optimal system to assess the mutagenic potential of chemicals.