Ethylene-triggered subcellular trafficking of CTR1 enhances the response to ethylene gas.

The phytohormone ethylene controls plant growth and stress responses. Ethylene-exposed dark-grown Arabidopsis seedlings exhibit dramatic growth reduction, yet the seedlings rapidly return to the basal growth rate when ethylene gas is removed. However, the underlying mechanism governing this acclimation of dark-grown seedlings to ethylene remains enigmatic. Here, we report that ethylene triggers the translocation of the Raf-like protein kinase CONSTITUTIVE TRIPLE RESPONSE1 (CTR1), a negative regulator of ethylene signaling, from the endoplasmic reticulum to the nucleus. Nuclear-localized CTR1 stabilizes the ETHYLENE-INSENSITIVE3 (EIN3) transcription factor by interacting with and inhibiting EIN3-BINDING F-box (EBF) proteins, thus enhancing the ethylene response and delaying growth recovery. Furthermore, Arabidopsis plants with enhanced nuclear-localized CTR1 exhibited improved tolerance to drought and salinity stress. These findings uncover a mechanism of the ethylene signaling pathway that links the spatiotemporal dynamics of cellular signaling components to physiological responses.

Operative versus conservative treatment of trigger thumb in children.

Trigger thumb is an uncommon anomaly in children with controversial management ranging from simple observation to surgical release. This study aimed to determine the clinical outcomes of surgical release versus conservative treatment. Data from 407 children with 511 trigger thumbs were collected from their medical records. To compare the final outcomes of conservative and operative treatments, age at onset, sex, affected side, familial history, treatment modality, time to conversion from conservative to surgical treatment, recurrence, and complications were analyzed. Forty-one children were excluded owing to loss during follow-up; thus, 366 children were finally included. Conservative treatment was administered to 96 children, of whom 25 experienced successful result and 68 experienced treatment failure and were subsequently treated surgically. There were no cases of post-operative recurrence. After 24 months of age, operative treatment had better outcomes than conservative treatment, which showed a higher failure rate.

Strigolactone elevates ethylene biosynthesis in etiolated Arabidopsis seedlings.

The gaseous phytohormone ethylene influences many aspects of plant life, including germination, fruit ripening, senescence, and stress responses. These diverse roles of ethylene occur in part through crosstalk with other phytohormones, which affects ethylene biosynthesis and signaling pathways. We have recently shown that the phytohormones, including gibberellic acid, abscisic acid, auxin, methyl jasmonate, and salicylic acid, regulate the stability of ACC synthases (ACSs), the rate-limiting enzymes in ethylene biosynthesis. Here, we report that treatment of etiolated Arabidopsis seedlings with strigolactone (SL) increases ethylene biosynthesis. SL does not influence ACS stability or ACS gene expression, but it increases the transcript levels of a subset of ACC oxidase (ACO) genes, thereby enhancing ethylene biosynthesis. Taken together with the results of our previous study, these findings demonstrate that most phytohormones differentially regulate ethylene biosynthesis in dark-grown Arabidopsis seedlings by affecting ACS stability and/or the transcript levels of ethylene biosynthesis genes.

Regulation of Ethylene Biosynthesis by Phytohormones in Etiolated Rice (Oryza sativa L.) Seedlings.

The gaseous hormone ethylene influences many aspects of plant growth, development, and responses to a variety of stresses. The biosynthesis of ethylene is tightly regulated by various internal and external stimuli, and the primary target of the regulation is the enzyme 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS), which catalyzes the rate-limiting step of ethylene biosynthesis. We have previously demonstrated that the regulation of ethylene biosynthesis is a common feature of most of the phytohormones in etiolated Arabidopsis seedlings via the modulation of the protein stability of ACS. Here, we show that various phytohormones also regulate ethylene biosynthesis from etiolated rice seedlings in a similar manner to those in Arabidopsis. Cytokinin, brassinosteroids, and gibberellic acid increase ethylene biosynthesis without changing the transcript levels of neither OsACS nor ACC oxidases (OsACO), a family of enzymes catalyzing the final step of the ethylene biosynthetic pathway. Likewise, salicylic acid and abscisic acid do not alter the gene expression of OsACS, but both hormones downregulate the transcript levels of a subset of ACO genes, resulting in a decrease in ethylene biosynthesis. In addition, we show that the treatment of the phytohormones results in distinct etiolated seedling phenotypes, some of which resemble ethylene-responsive phenotypes, while others display ethylene-independent morphologies, indicating a complicated hormone crosstalk in rice. Together, our study brings a new insight into crosstalk between ethylene biosynthesis and other phytohormones, and provides evidence that rice ethylene biosynthesis could be regulated by the post-transcriptional regulation of ACS proteins.

Dysplasia epiphysealis hemimelica: radiographic and magnetic resonance imaging features and clinical outcome of complete and incomplete resection.

OBJECTIVES: The objectives of this communication were to discuss radiographic and magnetic resonance (MR) imaging manifestations and clinical outcome after complete and incomplete resection of the mass of dysplasia epiphysealis hemimelica (DEH). MATERIALS AND METHODS: Clinical records, radiographs, and MR images of eight patients with DEH were retrospectively examined. Six patients were treated by complete excision of the lesional mass, and two patients were treated by incomplete resection at our University Hospitals during the period from 1980 to 2006. RESULTS: We found that, unlike in osteochondroma, DEH was radiographically not clearly separable from the underlying or host bone with preserved cortical bone and marrow continuity. The finding in the talus distinguished DEH from (osteochondroma-like) parosteal osteosarcoma, in which a radiolucent demarcation line clearly separated the tumor from the host bone. The DEH mass had a well-defined low to intermediate signal intensity on T1-weighted images and an intermediate to high signal intensity on T2-weighted images, with irregularity of the articular surface. Simple excision was performed in all patients. The excision was complete in six patients and incomplete in two patients whose lesions was juxta-articular in the ankle and articular in the knee, respectively. The residual mass slowly absorbed and vanished, resulting in mild flaring of the affected portion of the epiphysis. No local recurrence or complication was seen in any of the eight patients. CONCLUSIONS: Although the radiographic signs of DEH are characteristic, (osteochondroma-like) parosteal osteosarcoma should be differentiated from DEH when there is a radiolucent separation line between the mass and host bone in the talus. Simple excision was effective in the management of DEH if the deformity was not complicated. Incompletely excised masses resolved and vanished with time.

Non-specific phytohormonal induction of AtMYB44 and suppression of jasmonate-responsive gene activation in Arabidopsis thaliana.

The Arabidopsis thaliana transcription factor gene AtMYB44 was induced within 10 min by treatment with methyl jasmonate (MeJA). Wound-induced expression of the gene was observed in local leaves, but not in distal leaves, illustrating jasmonate-independent induction at wound sites. AtMYB44 expression was not abolished in Arabidopsis mutants insensitive to jasmonate (coi1), ethylene (etr1), or abscisic acid (abi3-1) when treated with the corresponding hormones. Moreover, various growth hormones and sugars also induced rapid AtMYB44 transcript accumulation. Thus, AtMYB44 gene activation appears to not be induced by any specific hormone. MeJA-induced activation of jasmonate-responsive genes such as JR2, VSP, LOXII, and AOS was attenuated in transgenic Arabidopsis plants overexpressing the gene (35S:AtMYB44), but significantly enhanced in atmyb44 knockout mutants. The 35S:MYB44 and atmyb44 plants did not show defectiveness in MeJA-induced primary root growth inhibition, indicating that the differences in jasmonate-responsive gene expression observed was not due to alterations in the jasmonate signaling pathway. 35S:AtMYB44 seedlings exhibited slightly elevated chlorophyll levels and less jasmonate- induced anthocyanin accumulation, demonstrating suppression of jasmonate-mediated responses and enhancement of ABA-mediated responses. These observations support the hypothesis of mutual antagonistic actions between jasmonate- and abscisic acid-mediated signaling pathways.