Light Control of Salt-Induced Proline Accumulation Is Mediated by ELONGATED HYPOCOTYL 5 in Arabidopsis

Plants have to adapt their metabolism to constantly changing environmental conditions, among which the availability of light and water is crucial in determining growth and development. Proline accumulation is one of the sensitive metabolic responses to extreme conditions; it is triggered by salinity or drought and is regulated by light. Here we show that red and blue but not far-red light is essential for salt-induced proline accumulation, upregulation of Delta 1-PYRROLINE-5-CARBOXYLATE SYNTHASE 1 (P5CS1) and downregulation of PROLINE DEHYDROGENASE 1 (PDH1) genes, which control proline biosynthetic and catabolic pathways, respectively. Chromatin immunoprecipitation and electrophoretic mobility shift assays demonstrated that the transcription factor ELONGATED HYPOCOTYL 5 (HY5) binds to G-box and C-box elements of P5CS1 and a C-box motif of PDH1. Salt-induced proline accumulation and P5CS1 expression were reduced in the hy5hyh double mutant, suggesting that HY5 promotes proline biosynthesis through connecting light and stress signals. Our results improve our understanding on interactions between stress and light signals, confirming HY5 as a key regulator in proline metabolism

Light Control of Salt-Induced Proline Accumulation is Mediated by Elongated Hypocotyl 5 in Arabidopsis

Plants have to adapt their metabolism to constantly changing environmental conditions, among which the availability of light and water is crucial in determining growth and development. Proline accumulation is one of the sensitive metabolic responses to extreme conditions; it is triggered by salinity or drought and is regulated by light. Here we show that red and blue but not far-red light is essential for salt-induced proline accumulation, upregulation of Delta 1-PYRROLINE-5-CARBOXYLATE SYNTHASE 1 (P5CS1) and downregulation of PROLINE DEHYDROGENASE 1 (PDH1) genes, which control proline biosynthetic and catabolic pathways, respectively. Chromatin immunoprecipitation and electrophoretic mobility shift assays demonstrated that the transcription factor ELONGATED HYPOCOTYL 5 (HY5) binds to G-box and C-box elements of P5CS1 and a C-box motif of PDH1. Salt-induced proline accumulation and P5CS1 expression were reduced in the hy5hyh double mutant, suggesting that HY5 promotes proline biosynthesis through connecting light and stress signals. Our results improve our understanding on interactions between stress and light signals, confirming HY5 as a key regulator in proline metabolism

A Sajóbábonyi Ipari Park környezeti hatása a Bábony-patakra

A dolgozatban Sajóbábony területén üzemelő Ipari Park Bábony-patakra gyakorolt hatása kerül vizsgálatra. A patak felszíni üledékét termikus elemzéssel és kémiai elemek kimutatásával vizsgáltuk, külön figyelmet fordítva az általunk ismert szennyezőanyagok előfordulására.BSc/BAFöldtudományig

Experience of employers and expectations of employees - Generation Z in focus

A dolgozat azokra a kérdésekre keresi a válaszokat, amelyek segítségével megismerhetjük a munkáltatók tapaszatalatait, és a Z generációs fiatalok munkával kapcsolatos elvárásait. A dolgozat célja, hogy olyan következtetéseket és javaslatokat fogalmazzon meg, melyek a gyakorlatban hasznosíthatók olyan szervezetek számára, melyek munkaerőhiánnyal és fluktuációs problémákkal küzdenek.MSc/MAemberi erőforrás tanácsadóK

Optogenetics: past, present and future

The term ‘optogenetics’ was introduced into the scientific literature less than a decade ago by Karl Deisseroth, developer of pioneering optogenetic techniques, who defined optogenetics as “the combination of genetic and optical methods to achieve gain or loss of function of well-defined events in specific cells of living tissue”. Since then this new field of biology has become a very exciting and rapidly developing area producing hundreds of scientific publications. New methods and tools have been developed and long-sought answers found in these new experimental systems. Discussion and full elaboration of every optogenetic approach and application are beyond the scope of this review, instead, it gives a short insight to (i) how light can be used to manipulate the membrane potential of various cells; (ii) how light-sensitive proteins can be used to regulate targeted gene expression, and (iii) how controlled release or spatio-temporal targeting of certain molecules can be modulated by light. Besides, the most widely used light-sensor proteins, including their structure, working mechanism and their involvement in existing optogenetic applications are also discussed

High-level expression and phosphorylation of phytochrome B modulates flowering time in Arabidopsis

Optimal timing of flowering in higher plants is crucial for successful reproduction and is coordinated by external and internal factors, including light and the circadian clock. In Arabidopsis, light-dependent stabilization of the rhythmically expressed CONSTANS (CO) is required for the activation of FLOWERING LOCUS T (FT), resulting in the initiation of flowering. Phytochrome A and cryptochrome photoreceptors stabilize CO in the evening by attenuating the activity of the CONSTITUTIVE PHOTOMORPHOGENIC 1-SUPPRESSOR OF PHYA-105 1 (COP1-SPA1) ubiquitin ligase complex, which promotes turnover of CO. In contrast, phytochrome B (phyB) facilitates degradation of CO in the morning and delays flowering. Accordingly, flowering is accelerated in phyB mutants. Paradoxically, plants overexpressing phyB also show early flowering, which may arise from an early phase of rhythmic CO expression. Here we demonstrate that overexpression of phyB induces FT transcription at dusk and in the night without affecting the phase or level of CO transcription. This response depends on the light-activated Pfr form of phyB that inhibits the function of the COP1-SPA1 complex by direct interactions. Our data suggest that attenuation of COP1 activity results in the accumulation of CO protein and subsequent induction of FT. We show that phosphorylation of Ser-86 inhibits this function of phyB by accelerating dark reversion and thus depletion of Pfr forms in the night. Our results explain the early flowering phenotype of phyB overexpression and reveal additional features of the molecular machinery by which photoreceptors mediate photoperiodism

ELONGATED HYPOCOTYL 5 mediates blue light signalling to the Arabidopsis circadian clock

Circadian clocks are gene networks producing 24-h oscillations at the level of clock gene expression that are synchronized to environmental cycles via light signals. The ELONGATED HYPOCOTYL 5 (HY5) transcription factor is a signalling hub acting downstream of several photoreceptors and is a key mediator of photomorphogenesis. Here we describe a mechanism by which light quality could modulate the pace of the circadian clock through governing abundance of HY5. We show that hy5 mutants display remarkably shorter period rhythms in blue but not in red light or darkness, and blue light is more efficient than red to induce accumulation of HY5 at transcriptional and post-transcriptional levels. We demonstrate that the pattern and level of HY5 accumulation modulates its binding to specific promoter elements of the majority of clock genes, but only a few of these show altered transcription in the hy5 mutant. Mathematical modelling suggests that the direct effect of HY5 on the apparently non-responsive clock genes could be masked by feedback from the clock gene network. We conclude that the information on the ratio of blue and red components of the white light spectrum is decoded and relayed to the circadian oscillator, at least partially, by HY5

A marked shift in the serotypes of pneumococci isolated from healthy children in Szeged, Hungary, over a 6-year period

Streptococcus pneumoniae is an important pathogen with significant morbidity and mortality rates worldwide, especially among children <5 years. Healthy carriers are the most important sources of pneumococcal infections, and the nasopharyngeal colonisation is the most prevalent among children attending communities such as day-care centres (DCCs). The conjugate pneumococcal vaccines (PCVs) were shown to have an impact on the colonisation, and so play an important role in inhibiting infections. In this study we compared the nasal carriage of healthy children attending DCCs in Szeged, Hungary in 2003/2004, when nobody was vaccinated, and in 2010, when already 1/5 of the children received PCV-7. Significant differences were observed in the serotype distribution, representing a marked shift from the previously widespread vaccine-types (mostly 6A or 14) to others (11A and 23F). The new serotypes showed higher antibiotic susceptibility. The bacterium exchange between children was clear from the pulsed-field gel electrophoresis (PFGE) patterns, and the circulation of certain international clones plays also a role in these dynamic changes

SUMOylation of PHYTOCHROME INTERACTING FACTOR 3 promotes photomorphogenesis in Arabidopsis thaliana.

-In Arabidopsis thaliana phytochrome B (phyB) is the dominant receptor of photomorphogenic development under red light. phyB interacts with a set of downstream regulatory proteins, including PHYTOCHROME INTERACTING FACTOR 3 (PIF3). The interaction of PIF3 and the photo-activated phyB leads to the rapid phosphorylation and degradation of PIF3 and also to the degradation of phyB, which events are required for proper photomorphogenesis. -Here we report that PIF3 is SUMOylated on the Lys13 (K13) residue and we could detect this posttranslational modification in a heterologous experimental system and also in planta. -We also found, that the SUMO acceptor site mutant PIF3(K13R) binds stronger to the target promoters than its SUMOylated, wild-type counterpart. Seedlings expressing PIF3(K13R) show elongated hypocotyl response, elevated photoprotection and higher transcriptional induction of red light responsive genes compared with plantlets expressing wild-type PIF3. -These observations are supported by the lower level of phyB in those plants which possess only PIF3(K13R) indicating that SUMOylation of PIF3 alters photomorphogenesis also via the regulation of phyB amount. Conclusively, whereas SUMOylation is generally connected to different stress responses it also fine tunes light signalling by reducing the biological activity of PIF3 thus promoting photomorphogenesis