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vegetative function [keywords]
- Life, Death and Immortality. [EDITORIAL]
- Acta Physiol (Oxf) 2014 Nov 20.
Since the childhood of humanity, man has been fascinated by the concept of mortality and the idea of the presence of immortals, may they be heavenly creatures, demons from an ancient world or etheric beings walking the earth, unseen, among us mere mortals. How fascinating it must have been when scientists, for the first time, could actually see the biochemical structure that contains immortal information, our genetic code, and which is, in its own way, immortal when transmitted from one generation to the other. (In today's world of high-throughput molecular biology, the sight of precipitated DNA in a test tube is, of course, no longer sensational. Rather, one might hear the occasional swear word when precipitation at that time in the protocol was not intended.) Creatures die, while their structural design plan does not. But not only are they capable of passing on these blueprints from generation to generation, but also to sacrifice individual cells or even tissues in a controlled manner for the common good of the whole body. This article is protected by copyright. All rights reserved.
- PnTgs1-like expression during reproductive development supports a role for RNA methyltransferases in the aposporous pathway. [JOURNAL ARTICLE]
- BMC Plant Biol 2014 Nov 18; 14(1):297.
BackgroundIn flowering plants, apomixis (asexual reproduction via seeds) is widely believed to result from failure of key regulators of the sexual female reproductive pathway. In the past few years, both differential display and RNA-seq comparative approaches involving reproductive organs of sexual plants and their apomictic counterparts have yielded extensive lists of candidate genes. Nevertheless, only a limited number of these genes have been functionally characterized, with few clues consequently available for understanding the molecular control of apomixis. We have previously identified several cDNA fragments with high similarity to genes involved in RNA biology and with differential amplification between sexual and apomictic Paspalum notatum plants. Here, we report the characterization of one of these candidates, namely, N69 encoding a protein of the S-adenosyl-L-methionine-dependent methyltransferases superfamily. The purpose of this work was to extend the N69 cDNA sequence and to characterize its expression at different developmental stages in both sexual and apomictic individuals.ResultsMolecular characterization of the N69 cDNA revealed homology with genes encoding proteins similar to yeast and mammalian trimethylguanosine synthase/PRIP-interacting proteins. These proteins play a dual role as ERK2-controlled transcriptional coactivators and madiators of sn(o)RNA and telomerase RNA cap trimethylation, and participate in mammals and yeast development. The N69-extended sequence was consequently renamed PnTgs1-like. Expression of PnTgs1-like during reproductive development was significantly higher in floral organs of sexual genotypes compared with apomicts. This difference was not detected in vegetative tissues. In addition, expression levels in reproductive tissues of several genotypes were negatively correlated with facultative apomixis rates. Moreover, in situ hybridization observations revealed that PnTgs1-like expression is relatively higher in ovules of sexual plants throughout development, from premeiosis to maturity. Tissues where differential expression is detected include nucellar cells, the site of aposporous initials differentiation in apomictic genotypes.ConclusionsOur results indicate that PnTgs1-like (formerly N69) encodes a trimethylguanosine synthase-like protein whose function in mammals and yeast is critical for development, including reproduction. Our findings also suggest a pivotal role for this candidate gene in nucellar cell fate, as its diminished expression is correlated with initiation of the apomictic pathway in plants.
- SAD1, an RNA polymerase I subunit A34.5 of rice, interacts with Mediator and controls various aspects of plant development. [JOURNAL ARTICLE]
- Plant J 2014 Nov 18.
The DWARF14 (D14) gene of rice functions within the signaling pathway of strigolactones, a group of plant hormones that inhibits shoot branching. We isolated a recessive mutant named super apical dormant (sad1-1) from a suppressor screen of d14-1. The growth of tillers (vegetative shoot branches) is suppressed in both the d14-1 sad1-1 double mutant and the sad1-1 single mutant. In addition, the sad1-1 mutant shows pleiotropic defects throughout development. SAD1 encodes an ortholog of RPA34.5, a subunit of RNA polymerase I (Pol I). Consequently, the level of ribosomal RNA (rRNA) is severely reduced in the sad1-1 mutant. These results indicate that proper ribosome function is a prerequisite for normal development in plants. The Arabidopsis ortholog of SAD1 was previously isolated as a Mediator-interacting protein. Here we show that SAD1 interacts physically with the Mediator complex through a direct binding with OsMED4, a component of the middle module of the Mediator complex in rice. It is known that Mediator interacts with Pol II, which transcribes mRNAs and functions as a central regulator of transcription. This study indicates a novel aspect of Mediator function in Pol I-controlled rRNA transcription. TFIIF2 and RPC53 are counterparts of RPA34.5 in Pol II and Pol III, respectively. We demonstrate that the rice orthologs of these proteins also interact with OsMED4. Our results suggest that interaction with MED4 in the Mediator complex is a common feature of the three types of RNA polymerases. This article is protected by copyright. All rights reserved.
- Dihydroxyacid dehydratase is important for gametophyte development and disruption causes increased susceptibility to salinity stress in Arabidopsis. [JOURNAL ARTICLE]
- J Exp Bot 2014 Nov 13.
Dihydroxyacid dehydratase (DHAD) catalyses a key step in the branched-chain amino acid (BCAA) biosynthetic pathway that exists in numerous organisms, including bacteria, fungi, and plants, but not humans. In Arabidopsis thaliana, DHAD is encoded by a single gene (AT3G23940), but its biological function in controlling plant development remains uncharacterized. In this study, we showed that DHAD is highly expressed in most vegetative and reproductive tissues. It is an essential gene, and complete disruption caused partial sterility in both male and female gametophyte phases. In addition, reduced expression of DHAD in knockdown mutants resulted in a reduction in the accumulation of all three BCAAs in roots and, as a consequence, led to a shorter root phenotype, which could be restored by an exogenous supplement of free BCAAs. Interestingly, the knockdown mutants became hypersensitive to salt stress, not to heavy metal stress, implying that BCAAs may act as osmolytes in salt tolerance. This would be the second amino acid shown to confer such a function in addition to the well-documented proline. Our results provide evidence that BCAA biosynthesis plays important roles in gametophyte and root development, and BCAA homeostasis contributes to the adaptation of Arabidopsis to salinity stress.
- Diadenosine pentaphosphate modulates glomerular arteriolar tone and glomerular filtration rate. [JOURNAL ARTICLE]
- Acta Physiol (Oxf) 2014 Nov 13.
Mechanisms and participating substances involved in the reduction of glomerular filtration (GFR) in contrast-induced acute kidney injury (CI-AKI) are still matter of debate. We hypothesized that diadenosine polyphosphates are released by the action of contrast media on tubular cells and may act on glomerular arterioles and reduce GFR.Freshly isolated rat tubules were treated with the contrast medium iodixanol (47 mg iodine/ml) at 37°C for 20 min. The content of Apn A (n=3-6) in the supernatant of treated tubules and in the plasma of healthy persons and patients with AKI was analyzed by using reversed phase chromatography, affinity chromatography and mass-spectrometry. GFR was obtained in conscious mice by inulin clearance. Concentration response curves for Apn A (n=3-6, 10(-12) -10(-5) mol/l) were measured in isolated perfused glomerular arterioles.Iodixanol treatment of tubules significantly increased the concentration of Apn A (n=3-5) in the supernatant. Ap6 A was below the detection limit. AKI patient show higher concentrations of Apn A compared to healthy. Application of Ap5 A significantly reduced the GFR in conscious mice. Ap5 A reduced afferent arteriolar diameters, but did not influence efferent arterioles. The constrictor effect on afferent arterioles was strong immediately after application, but weakened with time. Then non-selective P2 inhibitor suramin blocked the Ap5 A induced constriction.The data suggest that Ap5 A plays a role in the pathophysiology of CI-AKI. We show a contrast media induced release of Ap5 A from tubules, which might increase afferent arteriolar resistance and reduce the GFR. This article is protected by copyright. All rights reserved.
- LytR-CpsA-Psr enzymes as determinants of Bacillus anthracis secondary cell wall polysaccharide assembly. [JOURNAL ARTICLE]
- J Bacteriol 2014 Nov 10.
Bacillus anthracis, the causative agent of anthrax, replicates as chains of vegetative cells by regulating the separation of septal peptidoglycan. Surface (S)-layer proteins and associated proteins (BSLs) function as chain length determinants and bind to the secondary cell wall polysaccharide (SCWP). Here, we identified the B. anthracis lcpD mutant, which displays increased chain length and S-layer assembly defects due to diminished SCWP attachment to peptidoglycan. In contrast, the B. anthracis lcpB3 variant displayed reduced cell size and chain length, which could be attributed to increased deposition of BSLs. In other bacteria, LytR-CpsA-Psr (LCP) proteins attach wall teichoic acid (WTA) and polysaccharide capsule to peptidoglycan. B. anthracis does not synthesize these polymers yet its genome encodes six LCP homologues, which, when expressed in S. aureus, promote WTA attachment. We propose a model whereby B. anthracis LCPs promote attachment of SCWP precursors to discrete locations in the peptidoglycan, enabling BSL assembly and regulated separation of septal peptidoglycan.
- Reversible Cognitive, Motor and Driving Impairments in Severe Hypothyroidism. [JOURNAL ARTICLE]
- Thyroid 2014 Nov 8.
Background: Hypothyroidism has been associated with cognitive and motor impairments that are likely to constitute hazards in the operation of motor vehicles and a public safety risk; however, there is a paucity of data that would provide an evidence basis for recommendations to hypothyroid patients. The purpose of this study was to determine the specific neurological and psychological deficits consequent to hypothyroidism and whether they are of sufficient magnitude to impede the safe operation of motor vehicles. Methods: Repeated measurements were obtained in euthyroid, hypothyroid, and euthyroid hormone replaced states of thyroid cancer outpatients, at an academic medical center, who underwent thyroid hormone withdrawal preparation for radioiodine scanning. Study design used within-subject longitudinal "A-B- A" with each subject tested at 3 visits in the same sequence: euthyroid, hypothyroid, and euthyroid for a total of 32 subjects. Data on clinical status and cognitive performance were collected using standard instruments, including ThyDQoL and ThySRQ measures, National Adult Reading Test, Boston Naming Test, Mini-Mental State Exam, Wechsler Adult Intelligence Test-Revised, Letter Fluency FAS, and Beck inventory. Fine motor function was measured with an automated assessment panel, and driving performance on a commercial driving simulator. Results: In severe hypothyroidism (median TSH 83.2 mIU/L), fine motor performance of hands and reaction times in emergency braking tests were slowed, as well as subjective slowing reported on structured clinical scales. Depression was present, typified by vegetative and mood alterations, but lacking reported guilt and lowered self-esteem seen in other types of depression. Cognitive impairment was characterized by declines on speeded executive tests. In contrast, episodic memory performance improved over time regardless of thyroid hormone status. Braking times increased in hypothyroidism by 8.5%, equivalent to reports of effects from a blood alcohol level of 0.082 g/100 mL (above the USA legal driving limit). Conclusions: Transient profound hypothyroidism is characterized by reversible depression, decreased fine motor performance, slowed reaction times, and decreased processing speed. These data represent new empirical evidence that support the recommendation that complex activities requiring rapid responses, such as operating motor vehicles, should be avoided during hypothyroidism. This has broader implications regarding functional impairments and risk to public health.
- [The clinical and functional evaluation of the combined treatment of vasomotor rhinitis in the children]. [English Abstract, Journal Article]
- Vestn Otorinolaringol 2014; (4):31-5.
The objective of the present work was the comparative analysis of the results of the application of different methods for the treatment of the children presenting with vasomotor rhinitis. It was shown that the proposed combined approach including remedial therapy for the normalization of the function of the vegetative nervous system and the local application of fluctuating current to the nasal cavity mucosa has an advantage over the traditional modalities. Specifically, this newly developed simple and efficacious method for the combined conservative treatment of vasomotor rhinitis in the children has practically no contraindications for use, yields the most stable positive functional outcomes, and can by recommended for the application in both inpatient and outpatient settings to manage the patients with vasomotor rhinitis.
- Genetic, Molecular and Clinical Determinants for the Involvement of Aldosterone and Its Receptors in Major Depression. [JOURNAL ARTICLE]
- Nephron Physiol 2014 Nov 6.
Major depression (MDE) has metabolic and neuroendocrine correlates, which point to a biological overlap between MDE and cardiovascular diseases. Whereas the hypothalamic-pituitary-adrenocortical axis has long been recognized for its involvement in depression, the focus was mostly on cortisol/corticosterone, whereas aldosterone appears to be the 'forgotten' stress hormone. Part of the reason for this is that the receptors for aldosterone, the mineralocorticoid receptors (MR), were thought to be occupied by glucocorticoids in most parts of the brain. However, recently it turned out that aldosterone acts selectively in relevant mood-regulating brain areas, without competing with cortisol/corticosterone. These areas include the nucleus of the solitary tract (NTS), the amygdala and the paraventricular nucleus of the hypothalamus. These regions are intimately involved in the close relationship between emotional and vegetative symptoms. Genetic analysis supports the role of aldosterone and of MR-related pathways in the pathophysiology of depression. Functional markers for these pathways in animal models as well as in humans are available and allow an indirect assessment of NTS function. They include heart rate variability, baroreceptor reflex sensitivity, blood pressure, salt taste sensitivity and slow-wave sleep. MR activation in the periphery is related to electrolyte regulation. MR overactivity is a risk factor for diabetes mellitus and a trigger of inflammatory processes. These markers can be used not only to assist the development of new treatment compounds, but also for a personalized approach to treat patients with depression and related disorders by individual dose titration with an active medication, which targets this system. © 2014 S. Karger AG, Basel.
- Mitochondrial Function in Murine Skin Epithelium is Crucial for Hair Follicle Morphogenesis and Epithelial-Mesenchymal Interactions. [JOURNAL ARTICLE]
- J Invest Dermatol 2014 Nov 5.
Here, we studied how epithelial energy metabolism impacts overall skin development by selectively deleting intraepithelial mitochondrial DNA in mice by ablating a key maintenance factor (Tfam(EKO)), which induces loss of function of the electron transport chain (ETC). Quantitative (immuno)histomorphometry demonstrated that Tfam(EKO) mice showed significantly reduced hair follicle (HF) density and morphogenesis, fewer intrafollicular keratin15+ epithelial progenitor cells, increased apoptosis, and reduced proliferation. Tfam(EKO) mice also displayed premature entry into (aborted) HF cycling by apoptosis-driven HF regression (catagen). Ultrastructurally, Tfam(EKO) mice exhibited severe HF dystrophy, pigmentary abnormalities and telogen-like condensed dermal papillae. Epithelial HF progenitor cell differentiation (Plet1, Lrig1 Lef1, beta-catenin), sebaceous gland development (adipophilin, Scd1, oil red) and key mediators/markers of epithelial-mesenchymal interactions during skin morphogenesis (NCAM, versican, alkaline phosphatase) were all severely altered in Tfam(EKO) mice. Moreover, the number of mast cells, MHC class II+ or CD11b+ immunocytes in the skin mesenchyme was increased, and essentially no subcutis developed. Therefore, in contrast to their epidermal counterparts, pilosebaceous unit stem cells depend on a functional ETC. Most importantly, our findings point towards a frontier in skin biology: the coupling of HF keratinocyte mitochondrial function with the epithelial-mesenchymal interactions that drive overall development of the skin and its appendages.Journal of Investigative Dermatology accepted article preview online, 05 November 2014. doi:10.1038/jid.2014.475.