Selection of hygromycin-resistant Arabidopsis seedlings

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From network to phenotype : the dynamic wiring of an Arabidopsis transcriptional network induced by osmotic stress

Plants have established different mechanisms to cope with environmental fluctuations and accordingly fine-tune their growth and development through the regulation of complex molecular networks. It is largely unknown how the network architectures change and what the key regulators in stress responses and plant growth are. Here, we investigated a complex, highly interconnected network of 20 Arabidopsis transcription factors (TFs) at the basis of leaf growth inhibition upon mild osmotic stress. We tracked the dynamic behavior of the stress-responsive TFs over time, showing the rapid induction following stress treatment, specifically in growing leaves. The connections between the TFs were uncovered using inducible overexpression lines and were validated with transient expression assays. This study resulted in the identification of a core network, composed of ERF6, ERF8, ERF9, ERF59, and ERF98, which is responsible for most transcriptional connections. The analyses highlight the biological function of this core network in environmental adaptation and its redundancy. Finally, a phenotypic analysis of loss-of-function and gain-of-function lines of the transcription factors established multiple connections between the stress-responsive network and leaf growth

DFL2, a New Member of the Arabidopsis GH3 Gene Family, is Involved in Red Light-Specific Hypocotyl Elongation

A new GH3-related gene, designated DFL2, causes a short hypocotyl phenotype when overexpressed under red and blue light and a long hypocotyl when antisensed under red light conditions. Higher expression of this gene was observed in continuous white, blue and far-red light but the expression level was low in red light and darkness. DFL2 gene expression was induced transiently with red light pulse treatment. DFL2 transgenic plants exhibited a normal root phenotype including primary root elongation and lateral root formation, although primary root elongation was inhibited in antisense transgenic plants only under red light. The adult phenotypes of sense and antisense transgenic plants were not different from that of wild type. DFL2 promoter activity was observed in the hypocotyl. Our results suggest that DFL2 is located downstream of red light signal transduction and determines the degree of hypocotyl elongation.publishersversionPeer reviewe

Effects of tongue cleaning on bacterial flora in tongue coating and dental plaque: a crossover study

BACKGROUND: The effects of tongue cleaning on reconstruction of bacterial flora in dental plaque and tongue coating itself are obscure. We assessed changes in the amounts of total bacteria as well as Fusobacterium nucleatum in tongue coating and dental plaque specimens obtained with and without tongue cleaning. METHODS: We conducted a randomized examiner-blind crossover study using 30 volunteers (average 23.7 ± 3.2 years old) without periodontitis. After dividing randomly into 2 groups, 1 group was instructed to clean the tongue, while the other did not. On days 1 (baseline), 3, and 10, tongue coating and dental plaque samples were collected after recording tongue coating score (Winkel tongue coating index: WTCI). After a washout period of 3 weeks, the same examinations were performed with the subjects allocated to the alternate group. Genomic DNA was purified from the samples and applied to SYBR® Green-based real-time PCR to quantify the amounts of total bacteria and F. nucleatum. RESULTS: After 3 days, the WTCI score recovered to baseline, though the amount of total bacteria in tongue coating was significantly lower as compared to the baseline. In plaque samples, the bacterial amounts on day 3 and 10 were significantly lower than the baseline with and without tongue cleaning. Principal component analysis showed that variations of bacterial amounts in the tongue coating and dental plaque samples were independent from each other. Furthermore, we found a strong association between amounts of total bacteria and F. nucleatum in specimens both. CONCLUSIONS: Tongue cleaning reduced the amount of bacteria in tongue coating. However, the cleaning had no obvious contribution to inhibit dental plaque formation. Furthermore, recovery of the total bacterial amount induced an increase in F. nucleatum in both tongue coating and dental plaque. Thus, it is recommended that tongue cleaning and tooth brushing should both be performed for promoting oral health

Artificial colloids versus human albumin for the treatment of ovarian hyperstimulation syndrome: A retrospective cohort study

Background: The optimal colloid solution for the treatment of ovarian hyperstimulation syndrome (OHSS) remains to be established. Objective: We aimed to compare artificial colloids (AC) with human albumin (HA) for the treatment of OHSS. Materials and Methods: In this retrospective cohort study, data for OHSS participants were collected from a national inpatient database in Japan. The participants received intravenous fluid management with AC (n = 156) or HA (n = 127). We compared the two groups in terms of the length of stay, development of post-treatment complications, and termination surgery. Results: In multivariable linear regression analyses for log-transformed length of stay with reference to the OHSS participants receiving AC, the regression coefficient (95% confidence interval) in participants receiving HA was 0.03 (-0.04-0.09, p = 0.42). Thromboembolism occurred in two participants in the HA group and three participants in the AC group. Two participants in the HA group suffered renal failure during hospitalization. No participants underwent termination surgery in the two groups. Conclusions: The present results showed comparable efficacy between AC and HA for the treatment of OHSS. There were no significant differences in post-treatment complications between the two groups. Key words: Ovarian hyperstimulation syndrome, Treatment, Colloid, Length of stay

Identification and Characterization of Transcription Factors Regulating Arabidopsis \u3ci\u3eHAK5\u3c/i\u3e

Potassium (K) is an essential macronutrient for plant growth and reproduction. HAK5, an Arabidopsis high-affinity K transporter gene, plays an important role in K uptake. Its expression is up-regulated in response to K deprivation and is rapidly down-regulated when sufficient K levels have been re-established. To identify transcription factors regulating HAK5, an Arabidopsis TF FOX (Transcription Factor Full-length cDNA Over-eXpressor) library containing approximately 800 transcription factors was used to transform lines previously transformed with a luciferase reporter gene whose expression was driven by the HAK5 promoter. When grown under sufficient K levels, 87 lines with high luciferase activity were identified, and endogenous HAK5 expression was confirmed in 27 lines. Four lines overexpressing DDF2 (Dwarf and Delayed Flowering 2), JLO (Jagged Lateral Organs), TFII_A (Transcription initiation Factor II_A gamma chain) and bHLH121 (basic Helix–Loop–Helix 121) were chosen for further characterization by luciferase activity, endogenous HAK5 level and root growth in K-deficient conditions. Further analysis showed that the expression of these transcription factors increased in response to low K and salt stress. In comparison with controls, root growth under low K conditions was better in each of these four TF FOX lines. Activation of HAK5 expression by these four transcription factors required at least 310 bp of upstream sequence of the HAK5 promoter. These results indicate that at least these four transcription factors can bind to the HAK5 promoter in response to K limitation and activate HAK5 expression, thus allowing plants to adapt to nutrient stress. Includes supplementary figure and table

The YlmG protein has a conserved function related to the distribution of nucleoids in chloroplasts and cyanobacteria

<p>Abstract</p> <p>Background</p> <p>Reminiscent of their free-living cyanobacterial ancestor, chloroplasts proliferate by division coupled with the partition of nucleoids (DNA-protein complexes). Division of the chloroplast envelope membrane is performed by constriction of the ring structures at the division site. During division, nucleoids also change their shape and are distributed essentially equally to the daughter chloroplasts. Although several components of the envelope division machinery have been identified and characterized, little is known about the molecular components/mechanisms underlying the change of the nucleoid structure.</p> <p>Results</p> <p>In order to identify new factors that are involved in the chloroplast division, we isolated <it>Arabidopsis thaliana </it>chloroplast division mutants from a pool of random cDNA-overexpressed lines. We found that the overexpression of a previously uncharacterized gene (<it>AtYLMG1-1</it>) of cyanobacterial origin results in the formation of an irregular network of chloroplast nucleoids, along with a defect in chloroplast division. In contrast, knockdown of <it>AtYLMG1-1 </it>resulted in a concentration of the nucleoids into a few large structures, but did not affect chloroplast division. Immunofluorescence microscopy showed that AtYLMG1-1 localizes in small puncta on thylakoid membranes, to which a subset of nucleoids colocalize. In addition, in the cyanobacterium <it>Synechococcus elongates</it>, overexpression and deletion of <it>ylmG </it>also displayed defects in nucleoid structure and cell division.</p> <p>Conclusions</p> <p>These results suggest that the proper distribution of nucleoids requires the YlmG protein, and the mechanism is conserved between cyanobacteria and chloroplasts. Given that <it>ylmG </it>exists in a cell division gene cluster downstream of <it>ftsZ </it>in gram-positive bacteria and that <it>ylmG </it>overexpression impaired the chloroplast division, the nucleoid partitioning by YlmG might be related to chloroplast and cyanobacterial division processes.</p

A CRY-BIC negative-feedback circuitry regulating blue light sensitivity of Arabidopsis.

Cryptochromes are blue light receptors that regulate various light responses in plants. Arabidopsis cryptochrome 1 (CRY1) and cryptochrome 2 (CRY2) mediate blue light inhibition of hypocotyl elongation and long-day (LD) promotion of floral initiation. It has been reported recently that two negative regulators of Arabidopsis cryptochromes, Blue light Inhibitors of Cryptochromes 1 and 2 (BIC1 and BIC2), inhibit cryptochrome function by blocking blue light-dependent cryptochrome dimerization. However, it remained unclear how cryptochromes regulate the BIC gene activity. Here we show that cryptochromes mediate light activation of transcription of the BIC genes, by suppressing the activity of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), resulting in activation of the transcription activator ELONGATED HYPOCOTYL 5 (HY5) that is associated with chromatins of the BIC promoters. These results demonstrate a CRY-BIC negative-feedback circuitry that regulates the activity of each other. Surprisingly, phytochromes also mediate light activation of BIC transcription, suggesting a novel photoreceptor co-action mechanism to sustain blue light sensitivity of plants under the broad spectra of solar radiation in nature