RESUMEN
Synthetic modulators of plant 14-3-3s are promising chemical tools both for understanding the 14-3-3-related signaling pathways and controlling plant physiology. Herein, we describe a novel small-molecule inhibitor for 14-3-3 proteins of Arabidopsis thaliana. The inhibitor was identified from unexpected products in a stock solution in dimethyl sulfoxide (DMSO) of an in-house chemical library. Mass spectroscopy, mutant-based analyses, fluorescence polarization assays, and thermal shift assays revealed that the inhibitor covalently binds to an allosteric site of 14-3-3 with isoform selectivity. Moreover, infiltration of the inhibitor to Arabidopsis leaves suppressed the stomatal aperture. The inhibitor should provide new insight into the design of potent and isoform-selective 14-3-3 modulators.
Asunto(s)
Proteínas 14-3-3 , Arabidopsis , Isoformas de Proteínas , Proteínas 14-3-3/metabolismo , Proteínas 14-3-3/antagonistas & inhibidores , Proteínas 14-3-3/química , Arabidopsis/metabolismo , Arabidopsis/efectos de los fármacos , Isoformas de Proteínas/antagonistas & inhibidores , Isoformas de Proteínas/metabolismo , Proteínas de Arabidopsis/antagonistas & inhibidores , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/química , Bibliotecas de Moléculas Pequeñas/química , Bibliotecas de Moléculas Pequeñas/farmacología , Bibliotecas de Moléculas Pequeñas/metabolismo , Estructura Molecular , Descubrimiento de Drogas , Hojas de la Planta/química , Hojas de la Planta/metabolismoRESUMEN
The incidence of second primary neoplasms arising in the skin reconstructive flap (SNAF) is increasing because of the increase in head and neck flap reconstruction and cancer survival. Prognosis, optimal treatment, and their clinicopathological-genetic features are under debate and are difficult to diagnose. We retrospectively reviewed SNAFs based on a single center's experience over 20 years. Medical records and specimens of 21 patients with SNAF who underwent biopsies between April 2000 and April 2020 at our institute were retrospectively analyzed. Definite squamous cell carcinoma and the remaining neoplastic lesions were subclassified as flap cancer (FC) and precancerous lesions (PLs), respectively. Immunohistochemical studies focused on p53 and p16. TP53 sequencing was conducted using next-generation sequencing. Seven and 14 patients had definite FC and PL, respectively. The mean number of biopsies/latency intervals was 2.0 times/114 months and 2.5 times/108 months for FC and PL, respectively. All lesions were grossly exophytic and accompanied by inflamed stroma. In FC and PL, the incidences of altered p53 types were 43% and 29%, respectively, and those of positive p16 stains were 57% and 64%, respectively. Mutation of TP53 in FC and PL were 17% and 29%, respectively. All except one patient with FC under long-term immunosuppressive therapy survived in this study. SNAFs are grossly exophytic tumors with an inflammatory background and show a relatively low altered p53 and TP53 rate and a high p16 positivity rate. They are slow-growing neoplasms with good prognoses. Diagnosis is often difficult; therefore, repeated or excisional biopsy of the lesion may be desirable.
Asunto(s)
Neoplasias Primarias Secundarias , Humanos , Embarazo , Femenino , Proteína p53 Supresora de Tumor/genética , Estudios Retrospectivos , Cabeza , CuelloRESUMEN
BACKGROUND: There is a group of hypopharyngeal squamous cell carcinoma (HPSCC) patients for whom larynx-preserving open partial pharyngectomy (PP) and radiotherapy/chemoradiotherapy (RT/CRT) are indicated. We aimed to retrospectively evaluate the survival difference as there is no evidence directly comparing the two therapies. METHODS: This study evaluated HPSCC patients who were initially treated by PP or RT/CRT at our institution between January 2007 and October 2019. Overall survival (OS), disease-specific survival (DSS), laryngectomy-free survival (LFS), and local relapse-free survival (LRFS) were evaluated. The main analyses were performed with inverse probability of treatment weighting (IPTW) adjustments. Sensitivity analyses compared hazard ratios (HRs) obtained with three models: unadjusted, multivariate Cox regression, and propensity score-adjusted. RESULTS: Overall, 198 patients were enrolled; 63 and 135 underwent PP and RT/CRT, respectively. IPTW-adjusted 5-year OS, DSS, LFS, and LRFS rates in the PP and RT/CRT groups were 84.3% and 61.9% (p = 0.019), 84.9% and 75.8% (p = 0.168), 94.8% and 90.0% (p = 0.010), and 75.9% and 74.1% (p = 0.789), respectively. In the IPTW-adjusted regression analysis, PP was associated with a significant benefit regarding OS (HR 0.48, 95% confidence interval [CI] 0.26-0.90) and LFS (HR 0.17, 95% CI 0.04-0.77). The results obtained with the three models in the sensitivity analyses were qualitatively similar to those of the IPTW-adjusted models. CONCLUSION: Despite the risk of bias related to unadjusted factors, our results suggest that PP is associated with significantly better OS and LFS compared with RT/CRT for HPSCC.
Asunto(s)
Neoplasias de Cabeza y Cuello , Neoplasias Hipofaríngeas , Laringe , Humanos , Carcinoma de Células Escamosas de Cabeza y Cuello , Estudios Retrospectivos , Faringectomía , Neoplasias Hipofaríngeas/patología , Recurrencia Local de Neoplasia/terapia , Recurrencia Local de Neoplasia/etiología , Quimioradioterapia , Modelos de Riesgos ProporcionalesRESUMEN
Stomatal pores in the plant epidermis open and close to regulate gas exchange between leaves and the atmosphere. Upon light stimulation, the plasma membrane (PM) H+-ATPase is phosphorylated and activated via an intracellular signal transduction pathway in stomatal guard cells, providing a primary driving force for the opening movement. To uncover and manipulate this stomatal opening pathway, we screened a chemical library and identified benzyl isothiocyanate (BITC), a Brassicales-specific metabolite, as a potent stomatal-opening inhibitor that suppresses PM H+-ATPase phosphorylation. We further developed BITC derivatives with multiple isothiocyanate groups (multi-ITCs), which demonstrate inhibitory activity on stomatal opening up to 66 times stronger, as well as a longer duration of the effect and negligible toxicity. The multi-ITC treatment inhibits plant leaf wilting in both short (1.5 h) and long-term (24 h) periods. Our research elucidates the biological function of BITC and its use as an agrochemical that confers drought tolerance on plants by suppressing stomatal opening.
Asunto(s)
Proteínas de Arabidopsis , Estomas de Plantas , Estomas de Plantas/metabolismo , Luz , Resistencia a la Sequía , ATPasas de Translocación de Protón/metabolismo , Isotiocianatos/farmacología , Isotiocianatos/metabolismo , Proteínas de Arabidopsis/metabolismoRESUMEN
The quantification of stomatal pore size has long been a fundamental approach to understand the physiological response of plants in the context of environmental adaptation. Automation of such methodologies not only alleviates human labor and bias but also realizes new experimental research methods through massive analysis. Here, we present an image analysis pipeline that automatically quantifies stomatal aperture of Arabidopsis thaliana leaves from bright-field microscopy images containing mesophyll tissue as noisy backgrounds. By combining a You Only Look Once X-based stomatal detection submodule and a U-Net-based pore segmentation submodule, we achieved a mean average precision with an intersection of union (IoU) threshold of 50% value of 0.875 (stomata detection performance) and an IoU of 0.745 (pore segmentation performance) against images of leaf discs taken with a bright-field microscope. Moreover, we designed a portable imaging device that allows easy acquisition of stomatal images from detached/undetached intact leaves on-site. We demonstrated that this device in combination with fine-tuned models of the pipeline we generated here provides robust measurements that can substitute for manual measurement of stomatal responses against pathogen inoculation. Utilization of our hardware and pipeline for automated stomatal aperture measurements is expected to accelerate research on stomatal biology of model dicots.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Humanos , Arabidopsis/fisiología , Estomas de Plantas/fisiología , Hojas de la Planta/fisiología , MicroscopíaRESUMEN
Stomata are pores in the leaf epidermis of plants and their opening and closing regulate gas exchange and water transpiration. Stomatal movements play key roles in both plant growth and stress responses. In recent years, small molecules regulating stomatal movements have been used as a powerful tool in mechanistic studies, as well as key players for agricultural applications. Therefore, the development of new molecules regulating stomatal movement and the elucidation of their mechanisms have attracted much attention. We herein describe the discovery of 2,6-dihalopurines, AUs, as a new stomatal opening inhibitor, and their mechanistic study. Based on biological assays, AUs may involve in the pathway related with plasma membrane H+-ATPase phosphorylation. In addition, we identified leucine-rich repeat extensin proteins (LRXs), LRX3, LRX4 and LRX5 as well as RALF, as target protein candidates of AUs by affinity based pull down assay and molecular dynamics simulation. The mechanism of stomatal movement related with the LRXs-RALF is an unexplored pathway, and therefore further studies may lead to the discovery of new signaling pathways and regulatory factors in the stomatal movement.
Asunto(s)
Proteínas de Arabidopsis , Estomas de Plantas , Fosforilación , Membrana Celular/metabolismo , Pared Celular/metabolismo , ATPasas de Translocación de Protón , Proteínas de Arabidopsis/metabolismoRESUMEN
Reports on BCOR-CCNB3 sarcoma in the head and neck region are scarce, given their unknown etiology. An 18-year-old male patient presented a rapidly enlarging tumor extending from the right nasopharynx to the oropharynx. Histological examination showed a spindle cell sarcoma with BCOR-CCNB3 fusion detected by fluorescence in situ hybridization, and BCOR-CCNB3 was diagnosed. After three courses of alternating VDC-IE therapy, the patient underwent tumor resection based on the original tumor range with a minimal margin, using the mandibular swing technique. Radiation therapy (50.4 Gy) was administered postoperatively, followed by three additional courses of alternating VDC-IE therapy. The patient survived and showed no evidence of disease at 12 months postoperatively. BCOR-CCNB3 sarcoma is a chemotherapy-sensitive sarcoma, and conservative resection with a minimal margin that does not interfere with the treatment flow is preferable.
Asunto(s)
Faringe , Sarcoma , Masculino , Humanos , Adolescente , Faringe/patología , Hibridación Fluorescente in Situ , Proteínas Proto-Oncogénicas/genética , Proteínas Represoras/genética , Biomarcadores de Tumor , Sarcoma/genética , Sarcoma/cirugía , Ciclina BRESUMEN
Photoinduced benzylic C-H thiocyanation is described. A series of alkyl thiocyanates were efficiently obtained by using Selectfluor as the oxidant. Moreover, we accomplished the one-pot isothiocyanation following the C-H thiocyanation. The thiocyanates and isothiocyanates were applied to the divergent transformation of pharmaceuticals.
Asunto(s)
Hidrógeno , Tiocianatos , Isotiocianatos , Oxidantes , Preparaciones FarmacéuticasRESUMEN
BACKGROUND/AIM: There are no real-world comparative data of nivolumab doses of 3 mg/kg and 240 mg/body for recurrent/metastatic squamous cell carcinoma of the head and neck (R/M SCCHN). We investigated the efficacy and safety of nivolumab in treating recurrent/metastatic squamous cell carcinoma of the head and neck (R/M SCCHN) at different doses using real-world data. PATIENTS AND METHODS: R/M SCCHN patients who received nivolumab were divided into the 3 mg/kg and 240 mg/body groups and retrospectively examined for efficacy and safety. RESULTS: A total of 199 patients (3 mg/kg and 240 mg/body, 88 and 111 patients, respectively) were included. The 3 mg/kg vs. 240 mg/body groups had similar overall response rates (15% vs. 25, p=0.15), disease control rates (46% vs. 57%, p=0.15), overall survival (9.5 months vs. 10.9 months), and progression-free survival (3.7 months vs. 3.8 months, p=0.95). The incidence of immune-related adverse events was also similar in both groups. CONCLUSION: In R/M SCCHN patients, nivolumab showed similar efficacy and safety at doses of 3 mg/kg and 240 mg/body.
Asunto(s)
Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Inhibidores de Puntos de Control Inmunológico/administración & dosificación , Recurrencia Local de Neoplasia , Nivolumab/administración & dosificación , Carcinoma de Células Escamosas de Cabeza y Cuello/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Neoplasias de Cabeza y Cuello/inmunología , Neoplasias de Cabeza y Cuello/mortalidad , Neoplasias de Cabeza y Cuello/patología , Humanos , Inhibidores de Puntos de Control Inmunológico/efectos adversos , Masculino , Persona de Mediana Edad , Nivolumab/efectos adversos , Supervivencia sin Progresión , Estudios Retrospectivos , Carcinoma de Células Escamosas de Cabeza y Cuello/inmunología , Carcinoma de Células Escamosas de Cabeza y Cuello/mortalidad , Carcinoma de Células Escamosas de Cabeza y Cuello/secundario , Factores de Tiempo , Tokio , Adulto JovenRESUMEN
Stomata-small pores generally found on the leaves of plants-control gas exchange between plant and the atmosphere. Elucidating the mechanism that underlies such control through the regulation of stomatal opening/closing is important to understand how plants regulate photosynthesis and tolerate against drought. However, up-to-date, molecular components and their function involved in stomatal regulation are not fully understood. We challenged such problem through a chemical genetic approach by isolating and characterizing synthetic molecules that influence stomatal movement. Here, we describe that a small chemical collection, prepared during the development of C-H amination reactions, lead to the discovery of a Stomata Influencing Molecule (SIM); namely, a sulfonimidated oxazole that inhibits stomatal opening. The starting molecule SIM1 was initially isolated from screening of compounds that inhibit light induced opening of dayflower stomata. A range of SIM molecules were rapidly accessed using our state-of-the-art C-H amination technologies. This enabled an efficient structure-activity relationship (SAR) study, culminating in the discovery of a sulfonamidated oxazole derivative (SIM*) having higher activity and enhanced specificity against stomatal regulation. Biological assay results have shed some light on the mode of action of SIM molecules within the cell, which may ultimately lead to drought tolerance-conferring agrochemicals through the control of stomatal movement.
RESUMEN
Nivolumab administration to patients with organ transplantation history requires careful management. Herein, we report the case of a living-donor liver-transplant recipient, a 52-year-old man, with recurrent and metastatic hypopharyngeal cancer treated with nivolumab. He was diagnosed with T2N2bM0 stage IVA hypopharyngeal squamous cell carcinoma. While using oral immunosuppressants (cyclosporine and mycophenolate mofetil), the patient underwent right neck dissection followed by radiotherapy as an initial treatment. Three months after radiotherapy, positron emission tomography scans revealed multiple bone metastases. We administered two courses of the EXTREME regimen, comprising cisplatin, 5-fluorouracil, and cetuximab, as the first-line treatment for distal metastasis, but the patient presented with progressive disease. The patient was administered nivolumab as the second-line treatment. The programmed death-ligand 1 (PD-L1) expression level in a biopsy specimen of the primary hypopharyngeal tumor and resected specimen of the cervical lymph node metastasis was 40% and 10%, respectively. PD-L1 expression was not detected in hepatocytes of the liver biopsy sample obtained before nivolumab introduction. The patient received four courses of nivolumab 240 mg. Although liver dysfunction was alleviated by adjusting the dose of the hepatoprotective agent and cyclosporine, the progressive disease status persisted after completing nivolumab courses. The patient died of hypopharyngeal cancer progression.
Asunto(s)
Ciclosporinas , Neoplasias de Cabeza y Cuello , Neoplasias Hipofaríngeas , Trasplante de Hígado , Antígeno B7-H1/metabolismo , Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Humanos , Neoplasias Hipofaríngeas/diagnóstico por imagen , Neoplasias Hipofaríngeas/terapia , Donadores Vivos , Masculino , Persona de Mediana Edad , Nivolumab/uso terapéutico , Carcinoma de Células Escamosas de Cabeza y Cuello/tratamiento farmacológicoRESUMEN
Black thyroid is characterized by a rare pigment change observed almost exclusively in patients taking minocycline. We present the case of a 72-year-old man diagnosed with T3N3bM0 stage IVB hypopharyngeal squamous cell carcinoma who had been taking minocycline for approximately 18 months as a treatment for prurigo chronica multiformis. Initial treatment consisted of total pharyngolaryngoesophagectomy, bilateral neck dissection, total thyroidectomy, pharyngeal reconstruction using a free jejunal autograft, and creation of a permanent tracheostoma. During surgery, black discoloration of the thyroid and trachea was observed. Postoperative histological findings confirmed the black discoloration, with deposits of dark-brown, melanin-like granules observed in the thyroid, trachea, thyroid cartilage, and cricoid cartilage. Therefore, the black discoloration of the thyroid associated with the use of minocycline can extend to the thyroid cartilage, cricoid cartilage, and trachea. This information is important for surgeons to recognize in order to prevent unnecessary resection due to misdiagnosis.
Asunto(s)
Neoplasias Hipofaríngeas , Procedimientos de Cirugía Plástica , Neoplasias de la Tiroides , Anciano , Cartílago Cricoides/cirugía , Humanos , Neoplasias Hipofaríngeas/patología , Neoplasias Hipofaríngeas/cirugía , Masculino , Minociclina/efectos adversos , Pigmentación , Cartílago Tiroides/cirugía , Glándula Tiroides/patología , Neoplasias de la Tiroides/patología , TráqueaRESUMEN
Stomata in the epidermis of plants play essential roles in the regulation of photosynthesis and transpiration. Stomata open in response to blue light (BL) by phosphorylation-dependent activation of the plasma membrane (PM) H+-ATPase in guard cells. Under water stress, the plant hormone abscisic acid (ABA) promotes stomatal closure via the ABA-signaling pathway to reduce water loss. We established a chemical screening method to identify compounds that affect stomatal movements in Commelina benghalensis. We performed chemical screening using a protease inhibitor (PI) library of 130 inhibitors to identify inhibitors of stomatal movement. We discovered 17 PIs that inhibited light-induced stomatal opening by more than 50%. Further analysis of the top three inhibitors (PI1, PI2, and PI3; inhibitors of ubiquitin-specific protease 1, membrane type-1 matrix metalloproteinase, and matrix metalloproteinase-2, respectively) revealed that these inhibitors suppressed BL-induced phosphorylation of the PM H+-ATPase but had no effect on the activity of phototropins or ABA-dependent responses. The results suggest that these PIs suppress BL-induced stomatal opening at least in part by inhibiting PM H+-ATPase activity but not the ABA-signaling pathway. The targets of PI1, PI2, and PI3 were predicted by bioinformatics analyses, which provided insight into factors involved in BL-induced stomatal opening.
RESUMEN
PURPOSE: The standard induction chemotherapy for head and neck cancer is TPF [cisplatin (CDDP), docetaxel (DOC), and 5-fluorouracil (5-FU)]. We assessed whether one course of TPF could predict the efficacy of chemoradiotherapy for human papilloma virus (HPV)-related oropharyngeal squamous cell carcinoma. METHODS: We retrospectively reviewed 51 patients with stage III-IV HPV-related oropharyngeal squamous cell carcinoma who received one course of TPF with CDDP 60 mg/m2, DOC 60 mg/m2, and 5-FU 600 mg/m2. We recommended chemoradiotherapy for patients with complete or partial response (CR/PR), and surgery for those with stable or progressive disease (SD/PD). The endpoints were TPF-related adverse events and efficacy, chemoradiotherapy efficacy, and 2-year survival. RESULTS: Neutropenia was the most common grade ≥ 3 adverse event (88%). No grade 5 adverse events occurred. TPF achieved CR in 4% of patients (2/51), PR in 73% (37/51), SD in 20% (10/51), and PD in 4% (2/51). Concurrent cetuximab and radiotherapy (bio-radiotherapy, BRT) were administered to 61% of patients (31/51), concurrent CDDP and radiotherapy (CDDP-RT) to 16% (8/51), RT alone to 2% (1/51), and surgery was performed for 22% (11/51). CR was achieved in 85% of the chemoradiotherapy group, and the rate tended to increase with TPF efficacy. CR was achieved in 84% (26/31) of patients receiving BRT, 88% (7/8) receiving CDDP-RT, and 100% (1/1) receiving RT. The 2-year survival rates were 92% overall, and 97% and 79% in the chemoradiotherapy and surgery groups, respectively. CONCLUSIONS: When facing difficulty in deciding between chemoradiotherapy and surgery, one course of TPF may be an effective option.
Asunto(s)
Neoplasias de Cabeza y Cuello , Taxoides , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Quimioradioterapia , Cisplatino , Fluorouracilo , Humanos , Quimioterapia de Inducción , Papillomaviridae , Estudios Retrospectivos , Carcinoma de Células Escamosas de Cabeza y Cuello/terapiaRESUMEN
Herein, we report a case of an occult thyroid cancer that was not detected as a primary tumor on preoperative ultrasonography or postoperative pathological examination, although a diagnosis of papillary thyroid carcinoma metastasis was made owing to the presence of a mass in the right upper neck. Needle biopsy of the mass in the right upper neck revealed positive results for thyroglobulin and TTF-1 on immunostaining, and a papillary thyroid carcinoma was observed with papillary and follicular patterns. We suspected papillary thyroid carcinoma (T0N1bM0) or ectopic papillary thyroid carcinoma. Accordingly, we performed total thyroidectomy, central lymph node dissection, right lateral neck dissection, and resection of the superficial lobe of the right parotid. A postoperative pathological examination of 5-mm slices of the specimen revealed no primary tumor in the thyroid. However, a hyalinized image of the thyroid indicated that a micropapillary thyroid carcinoma might have spontaneously disappeared. As there was no normal thyroid tissue in the metastasis to the superior internal jugular lymph node, the tumor was unlikely to be an ectopic papillary thyroid carcinoma. Therefore, we made a diagnosis of a papillary thyroid carcinoma (pT0N1bM0). After surgery, we determined that the tumor belonged to a high-risk group of papillary thyroid carcinomas and a poor-prognosis group of symptomatic papillary thyroid microcarcinomas; accordingly, ablation was performed with 30 mCi iodine-131. There was no recurrence or metastasis 24 months after the first surgery.
RESUMEN
Stable endosymbiotic relationships between cnidarian animals and dinoflagellate algae are vital for sustaining coral reef ecosystems. Recent studies have shown that elevated seawater temperatures can cause the collapse of their endosymbiosis, known as 'bleaching', and result in mass mortality. However, the molecular interplay between temperature responses and symbiotic states still remains unclear. To identify candidate genes relevant to the symbiotic stability, we performed transcriptomic analyses under multiple conditions using the symbiotic and apo-symbiotic (symbiont free) Exaiptasia diaphana, an emerging model sea anemone. Gene expression patterns showed that large parts of differentially expressed genes in response to heat stress were specific to the symbiotic state, suggesting that the host sea anemone could react to environmental changes in a symbiotic state-dependent manner. Comparative analysis of expression profiles under multiple conditions highlighted candidate genes potentially important in the symbiotic state transition under heat-induced bleaching. Many of these genes were functionally associated with carbohydrate and protein metabolisms in lysosomes. Symbiont algal genes differentially expressed in hospite encode proteins related to heat shock response, calcium signaling, organellar protein transport, and sugar metabolism. Our data suggest that heat stress alters gene expression in both the hosts and symbionts. In particular, heat stress may affect the lysosome-mediated degradation and transportation of substrates such as carbohydrates through the symbiosome (phagosome-derived organelle harboring symbiont) membrane, which potentially might attenuate the stability of symbiosis and lead to bleaching-associated symbiotic state transition.
Asunto(s)
Cnidarios/genética , Dinoflagelados/genética , Ambiente , Perfilación de la Expresión Génica , Simbiosis , Transcriptoma , Animales , Cnidarios/metabolismo , Dinoflagelados/metabolismo , Regulación de la Expresión GénicaRESUMEN
Reef-building corals thrive in nutrient-poor marine environments because of an obligate symbiosis with photosynthetic dinoflagellates of the genus Symbiodinium Symbiosis is established in most corals through the uptake of Symbiodinium from the environment. Corals are sessile for most of their life history, whereas free-living Symbiodinium are motile; hence, a mechanism to attract Symbiodinium would greatly increase the probability of encounter between host and symbiont. Here, we examined whether corals can attract free-living motile Symbiodinium by their green fluorescence, emitted by the excitation of endogenous GFP by purple-blue light. We found that Symbiodinium have positive and negative phototaxis toward weak green and strong purple-blue light, respectively. Under light conditions that cause corals to emit green fluorescence, (e.g., strong blue light), Symbiodinium were attracted toward live coral fragments. Symbiodinium were also attracted toward an artificial green fluorescence dye with similar excitation and emission spectra to coral-GFP. In the field, more Symbiodinium were found in traps painted with a green fluorescence dye than in controls. Our results revealed a biological signaling mechanism between the coral host and its potential symbionts.
Asunto(s)
Cnidarios/metabolismo , Cnidarios/microbiología , Dinoflagelados/fisiología , Fluorescencia , Simbiosis , Animales , Antozoos/metabolismo , Antozoos/microbiología , Arrecifes de Coral , Dinoflagelados/clasificación , FilogeniaRESUMEN
Light is essential for photosynthesis, but the amounts of light that exceed an organism's assimilation capacity can cause serious damage1. Photosynthetic organisms minimize such potential harm through protection mechanisms collectively referred to as non-photochemical quenching2. One mechanism of non-photochemical quenching called energy-dependent quenching (qE quenching) is readily activated under high-light conditions and dissipates excess energy as heat. LIGHT-HARVESTING COMPLEX STRESS-RELATED PROTEINS 1 and 3 (LHCSR1 and LHCSR3) have been proposed to mediate qE quenching in the green alga Chlamydomonas reinhardtii when grown under high-light conditions3. LHCSR3 induction requires a blue-light photoreceptor, PHOTOTROPIN (PHOT)4, although the signal transduction pathway between PHOT and LHCSR3 is not yet clear. Here, we identify two phot suppressor loci involved in qE quenching: de-etiolated 1 (det1)5 and damaged DNA-binding 1 (ddb1)6. Using a yeast two-hybrid analysis and an inhibitor assay, we determined that these two genetic elements are part of a protein complex containing CULLIN 4 (CUL4). These findings suggest a photoprotective role for the putative E3 ubiquitin ligase CUL4-DDB1DET1 in unicellular photosynthetic organisms that may mediate blue-light signals to LHCSR1 and LHCSR3 gene expression.
Asunto(s)
Chlamydomonas reinhardtii/fisiología , Proteínas de Plantas/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Etiolado , Regulación de la Expresión Génica de las Plantas , Prueba de Complementación Genética , Luz , Complejos de Proteína Captadores de Luz/genética , Complejos de Proteína Captadores de Luz/metabolismo , Mutación , Proteínas de Plantas/genética , Técnicas del Sistema de Dos Híbridos , Ubiquitina-Proteína Ligasas/genéticaRESUMEN
Reef-building corals form symbiotic relationships with dinoflagellates of the genus Symbiodinium. Symbiodinium are genetically and physiologically diverse, and corals may be able to adapt to different environments by altering their dominant Symbiodinium phylotype. Notably, each coral species associates only with specific Symbiodinium phylotypes, and consequently the diversity of symbionts available to the host is limited by the species specificity. Currently, it is widely presumed that species specificity is determined by the combination of cell-surface molecules on the host and symbiont. Here we show experimental evidence supporting a new model to explain at least part of the specificity in coral-Symbiodinium symbiosis. Using the laboratory model Aiptasia-Symbiodinium system, we found that symbiont infectivity is related to cell size; larger Symbiodinium phylotypes are less likely to establish a symbiotic relationship with the host Aiptasia. This size dependency is further supported by experiments where symbionts were replaced by artificial fluorescent microspheres. Finally, experiments using two different coral species demonstrate that our size-dependent-infection model can be expanded to coral-Symbiodinium symbiosis, with the acceptability of large-sized Symbiodinium phylotypes differing between two coral species. Thus the selectivity of the host for symbiont cell size can affect the diversity of symbionts in corals.
Asunto(s)
Antozoos/fisiología , Dinoflagelados/citología , Simbiosis/fisiología , Animales , Tamaño de la Célula , Dinoflagelados/fisiología , Especificidad de la EspecieRESUMEN
We synthesized neutral Ru(II) complexes cis-Ru(bpy)2(CN)2 (bpy = 2,2'-bipyridine), cis-Ru(dmb)2(CN)2 (dmb = 4,4'-dimethyl-2,2'-bipyridine), cis-Ru(dbb)2(CN)2 (dbb = 4,4'-di-tert-butyl-2,2'-bipyridine), and cis-Ru(phen)2(CN)2 (phen = 1,10-phenanthroline) and optically resolved them into respective enantiomers using high-performance liquid chromatography with a chiral column. The absolute configuration of enantiomer of cis-Ru(dbb)2(CN)2 was determined by an X-ray crystallography. Upon photoirradiation, the entire enantiomers of the complexes underwent the racemization with considerably slow rates (k = 1 × 10(-6) to 1 × 10(-5) s(-1)) and small quantum yields (Ï = 1 × 10(-6) to 1 × 10(-5)). The photoracemization was concluded to proceed via a five-coordinate pyramidal intermediate with the base plane composed of Ru, bidentate polypyridine, and two cyanides and the axial ligand of monodentate polypyridine. We derived the equations for photoracemization rate and quantum yield by a kinetics analysis of the photoracemization reaction that depended on polypyridine ligand, solvent, temperature, wavelength and intensity of irradiation light, and emission lifetime. From the temperature-dependent photoracemization reaction, the energy gap between (3)MLCT (metal-to-ligand charge transfer) and (3)d-d* states was estimated as ΔE = 4000-5000 cm(-1), and the energy of invisible (3)d-d* state was estimated to be ca. 20â¯500 cm(-1), which was in good agreement with that of [Ru(bpy)3](2+).