Download the Free Unbound MEDLINE PubMed App to your smartphone or tablet.
Available for iPhone, iPad, iPod touch, and Android.
vegetative function [keywords]
- Tetrameric c-di-GMP Mediates Effective Transcription Factor Dimerization to Control Streptomyces Development. [JOURNAL ARTICLE]
- Cell 2014 Aug 28; 158(5):1136-1147.
The cyclic dinucleotide c-di-GMP is a signaling molecule with diverse functions in cellular physiology. Here, we report that c-di-GMP can assemble into a tetramer that mediates the effective dimerization of a transcription factor, BldD, which controls the progression of multicellular differentiation in sporulating actinomycete bacteria. BldD represses expression of sporulation genes during vegetative growth in a manner that depends on c-di-GMP-mediated dimerization. Structural and biochemical analyses show that tetrameric c-di-GMP links two subunits of BldD through their C-terminal domains, which are otherwise separated by ∼10 Å and thus cannot effect dimerization directly. Binding of the c-di-GMP tetramer by BldD is selective and requires a bipartite RXD-X8-RXXD signature. The findings indicate a unique mechanism of protein dimerization and the ability of nucleotide signaling molecules to assume alternative oligomeric states to effect different functions.
- Measuring consciousness in coma and related states. [Journal Article, Review]
- World J Radiol 2014 Aug 28; 6(8):589-97.
Consciousness is a prismatic and ambiguous concept that still eludes any universal definition. Severe acquired brain injuries resulting in a disorder of consciousness (DOC) provide a model from which insights into consciousness can be drawn. A number of recent studies highlight the difficulty in making a diagnosis in patients with DOC based only on behavioral assessments. Here we aim to provide an overview of how neuroimaging techniques can help assess patients with DOC. Such techniques are expected to facilitate a more accurate understanding of brain function in states of unconsciousness and to improve the evaluation of the patient's cognitive abilities by providing both diagnostic and prognostic indicators.
- Interplay between sugar and hormone signaling pathways modulate floral signal transduction. [Journal Article, Review]
- Front Genet 2014.:218.
NOMENCLATURE The following nomenclature will be used in this article: Names of genes are written in italicized upper-case letters, e.g., ABI4.Names of proteins are written in non-italicized upper-case letters, e.g., ABI4.Names of mutants are written in italicized lower-case letters, e.g., abi4. The juvenile-to-adult and vegetative-to-reproductive phase transitions are major determinants of plant reproductive success and adaptation to the local environment. Understanding the intricate molecular genetic and physiological machinery by which environment regulates juvenility and floral signal transduction has significant scientific and economic implications. Sugars are recognized as important regulatory molecules that regulate cellular activity at multiple levels, from transcription and translation to protein stability and activity. Molecular genetic and physiological approaches have demonstrated different aspects of carbohydrate involvement and its interactions with other signal transduction pathways in regulation of the juvenile-to-adult and vegetative-to-reproductive phase transitions. Sugars regulate juvenility and floral signal transduction through their function as energy sources, osmotic regulators and signaling molecules. Interestingly, sugar signaling has been shown to involve extensive connections with phytohormone signaling. This includes interactions with phytohormones that are also important for the orchestration of developmental phase transitions, including gibberellins, abscisic acid, ethylene, and brassinosteroids. This article highlights the potential roles of sugar-hormone interactions in regulation of floral signal transduction, with particular emphasis on Arabidopsis thaliana mutant phenotypes, and suggests possible directions for future research.
- Genomic organization, differential expression, and functional analysis of the SPL gene family in Gossypium hirsutum. [JOURNAL ARTICLE]
- Mol Genet Genomics 2014 Aug 27.
SQUAMOSA promoter binding protein-like (SPL) genes encode plant-specific transcription factors that are involved in many fundamental developmental processes. Certain SPL genes contain sequences complementary to miR156, a microRNA (miRNA) that plays a role in modulating plant gene expression. In this study, 30 SPL genes were identified in the reference genome of Gossypium raimondii and 24 GhSPLs were cloned from Gossypium hirsutum. G. raimondii is regarded as the putative contributor of the D-subgenome of G. hirsutum. Comparative analysis demonstrated sequence conservation between GhSPLs and other plant species. GhSPL genes could be classified into seven subclades based on phylogenetic analysis, diverse intron-exon structure, and motif prediction. Within each subclade, genes shared a similar structure. Sequence and experimental analysis predicted that 18 GhSPL genes are putative targets of GhmiR156. Additionally, tissue-specific expression analysis of GhSPL genes showed that their spatiotemporal expression patterns during development progressed differently, with most genes having high transcript levels in leaves, stems, and flowers. Finally, overexpression of GhSPL3 and GhSPL18 in Arabidopsis plants demonstrated that these two genes are involved in the development of leaves and second shoots and play an integral role in promoting flowering. The flowering integrator GhSOC1 may bind to the promoter of GhSPL3 but not GhSPL18 to regulate flowering. In conclusion, our analysis of GhSPL genes will provide some gene resources and a further understanding of GhSPL3 and GhSPL18 function in flowering promotion. Furthermore, the comparative genomics and functional analysis deepened our understanding of GhSPL genes during upland cotton vegetative and reproductive growth.
- Arabidopsis inositol pentakisphosphate 2-kinase, AtIPK1, is required for growth and modulates phosphate homeostasis at the transcriptional level. [JOURNAL ARTICLE]
- Plant J 2014 Aug 23.
Inositol hexakisphosphate (IP6 ) provides a phosphorous reservoir in plant seeds; in addition, along with its biosynthesis intermediates and derivatives, IP6 also plays important roles in diverse developmental and physiological processes. Disruption of the Arabidopsis inositol pentakisphosphate 2-kinase coding gene AtIPK1 was previously shown to reduce IP6 content in vegetative tissues and affect phosphate (Pi) sensing. Here we show that AtIPK1 is required for sustaining plant growth, as null mutants are non-viable. An incomplete loss-of-function mutant, atipk1-1, exhibited disturbed Pi homeostasis and overaccumulated Pi as a consequence of increased Pi uptake activity and root-to-shoot Pi translocation. The atipk1-1 mutants also showed a Pi-deficiency-like root system architecture with reduced primary root and enhanced lateral root growth. Transcriptome analysis indicated that a subset of Pi starvation-responsive genes was transcriptionally perturbed in the atipk1-1 mutants and the expression of multiple genes involved in Pi uptake, allocation, and remobilization was increased. Genetic and transcriptional analyses suggest that disturbance of Pi homeostasis caused by atipk1 mutation involved components in addition to PHR1(-like) transcription factors. Notably, the transcriptional increase of a number of Pi starvation-responsive genes in the atipk1-1 mutants is correlated with the reduction of histone variant H2A.Z occupation in chromatin. The myo-inositol-1-phosphate synthase mutants, atmips1 and atmips2 with comparable reduction in vegetative IP6 to that in the atipk1-1 mutants did not overaccumulate Pi, suggesting that Pi homeostasis modulated by AtIPK1 is not solely attributable to IP6 level. This study reveals that AtIPK1 has important roles in growth and Pi homeostasis. This article is protected by copyright. All rights reserved.
- A stearoyl-acyl carrier protein desaturase, NbSACPD-C, is critical for ovule development in Nicotiana benthamiana. [JOURNAL ARTICLE]
- Plant J 2014 Aug 23.
Stearoyl-acyl carrier protein desaturase (SACPD) activity is essential for production of the major unsaturated fatty acids (UFAs) in plant lipids. We report here the characterization of three SACPD genes from Nicotiana benthamiana, NbSACPD-A, -B, and -C. All three genes share high similarity to AtSSI2/FAB2 (Suppressor of Salicylic acid-Insensitivity2/Fatty Acid Biosynthesis2), the primary SACPD isoform in Arabidopsis. Knocking down the expression of individual or combinations of NbSACPDs by an artificial microRNA approach resulted in significantly reduced accumulation of 18C UFAs and elevated levels of 18:0-FA in leaves, indicating that all three genes participated in fatty acid desaturation. The triple knockdown (KD) plants displayed severe growth phenotypes, including spontaneous cell death and dwarfing. While no vegetative morphologic abnormality was observed in NbSACPD-A, -B, or -C KD plants, strikingly, NbSACPD-C KD plants produced small fruits with aborted ovules. Reciprocal crosses with wild-type and NbSACPD-C KD plants revealed that knocking down NbSACPD-C expression caused female, but not male, sterility. Furthermore, arrested ovule development and significantly altered lipid composition in ovaries were observed in NbSACPD-C KD plants, consistent with the predominant NbSACPD-C expression in ovules. The ovule development defect was fully complemented by coexpressing an amiRNA-resistant NbSACPD-C variant in the NbSACPD-C KD background, further supporting a specific requirement for NbSACPD-C in female fertility. Our results thus indicated that NbSACPD-C plays a critical role maintaining membrane lipid composition in ovule development for female fertility in N. benthamiana, complementing and extending prior understanding on the well-demonstrated roles of SACPDs in biotic and abiotic stresses. This article is protected by copyright. All rights reserved.
- The post-translational modification of the Clostridium difficile flagellin affects motility, cell surface properties and virulence. [JOURNAL ARTICLE]
- Mol Microbiol 2014 Aug 18.
Clostridium difficile is a prominent nosocomial pathogen, proliferating and causing enteric disease in individuals with a compromised gut microflora. We characterised the post-translational modification of flagellin in C. difficile 630. The structure of the modification was solved by nuclear magnetic resonance and shown to contain an N-acetylglucosamine substituted with a phosphorylated N-methyl-L-threonine. A reverse genetics approach investigated the function of the putative four-gene modification locus. All mutants were found to have truncated glycan structures by LC-MS/MS, taking into account bioinformatic analysis, we propose that the open reading frame CD0241 encodes a kinase involved in the transfer of the phosphate to the threonine, the CD0242 protein catalyses the addition of the phosphothreonine to the N-acetylglucosamine moiety and CD0243 transfers the methyl group to the threonine. Some mutations affected motility and caused cells to aggregate to each other and abiotic surfaces. Altering the structure of the flagellin modification impacted on colonisation and disease recurrence in a murine model of infection, showing that alterations in the surface architecture of C. difficile vegetative cells can play a significant role in disease. We show that motility is not a requirement for colonisation, but that colonisation was compromised when the glycan structure was incomplete.
- Bibliometric performance of Acta Physiologica. [EDITORIAL]
- Acta Physiol (Oxf) 2014 Aug 14.
One step up in the ranking of Acta Physiologica, that is the result of the 2013 impact factor. We now rank ninth out of 81 journals the field of physiology. If only those publication organs are considered that are not completely focused on reviews or on specialized fields, Acta Physiologica ranks number four. This article is protected by copyright. All rights reserved.
- Responses of a rice-field cyanobacterium Anabaena siamensis TISTR-8012 upon exposure to PAR and UV radiation. [JOURNAL ARTICLE]
- J Plant Physiol 2014 Jul 25; 171(16):1545-1553.
The effects of PAR and UV radiation and subsequent responses of certain antioxidant enzymatic and non-enzymatic defense systems were studied in a rice field cyanobacterium Anabaena siamensis TISTR 8012. UV radiation resulted in a decline in growth accompanied by a decrease in chlorophyll a and photosynthetic efficiency. Exposure of cells to UV radiation significantly affected the differentiation of vegetative cells into heterocysts or akinetes. UV-B radiation caused the fragmentation of the cyanobacterial filaments conceivably due to the observed oxidative stress. A significant increase of reactive oxygen species in vivo and DNA strand breaks were observed in UV-B exposed cells followed by those under UV-A and PAR radiation, respectively. The UV-induced oxidative damage was alleviated due to an induction of antioxidant enzymatic/non-enzymatic defense systems. In response to UV irradiation, the studied cyanobacterium exhibited a significant increase in antioxidative enzyme activities of superoxide dismutase, catalase and peroxidase. Moreover, the cyanobacterium also synthesized some UV-absorbing/screening substances. HPLC coupled with a PDA detector revealed the presence of three compounds with UV-absorption maxima at 326, 331 and 345nm. The induction of the biosynthesis of these UV-absorbing compounds was found under both PAR and UV radiation, thus suggesting their possible function as an active photoprotectant.
- Elucidation of sevadicin, a novel non-ribosomal peptide secondary metabolite produced by the honey bee pathogenic bacterium Paenibacillus larvae. [Journal Article, Research Support, Non-U.S. Gov't]
- Environ Microbiol 2014 May; 16(5):1297-309.
American foulbrood (AFB) caused by the bee pathogenic bacterium Paenibacillus larvae is the most devastating bacterial disease of honey bees worldwide. From AFB-dead larvae, pure cultures of P. larvae can normally be cultivated indicating that P. larvae is able to defend its niche against all other bacteria present. Recently, comparative genome analysis within the species P. larvae suggested the presence of gene clusters coding for multi-enzyme complexes, such as non-ribosomal peptide synthetases (NRPSs). The products of these enzyme complexes are known to have a wide range of biological activities including antibacterial activities. We here present our results on antibacterial activity exhibited by vegetative P. larvae and the identification and analysis of a novel antibacterially active P. larvae tripeptide (called sevadicin; Sev) produced by a NRPS encoded by a gene cluster found in the genome of P. larvae. Identification of Sev was ultimately achieved by comparing the secretome of wild-type P. larvae with knockout mutants of P. larvae lacking production of Sev. Subsequent mass spectrometric studies, enantiomer analytics and chemical synthesis revealed the sequence and configuration of the tripeptide, D-Phe-D-ALa-Trp, which was shown to have antibacterial activity. The relevance of our findings is discussed in respect to host-pathogen interactions.