RESUMEN

In this paper, we demonstrated the biological effects of acute low-dose neutrons on the whole body of rats and investigated the impact of that level of neutron dose to induce an in vivo radio-adaptive response. To understand the radio-adaptive response, the examined animals were exposed to acute neutron radiation doses of 5 and 10 mSv, followed by a 50 mSv challenge dose after 14 days. After irradiation, all groups receiving single and double doses were kept in cages for one day before sampling. The electron paramagnetic resonance (EPR) method was used to estimate the radiation-induced radicals in the blood, and some hematological parameters and lipid peroxidation (MDA) were determined. A comet assay was performed beside some of the antioxidant enzymes [catalase enzyme (CAT), superoxide dismutase (SOD), and glutathione (GSH)]. Seven groups of adult male rats were classified according to their dose of neutron exposure. Measurements of all studied markers are taken one week after harvesting, except for hematological markers, within 2 h. The results indicated lower production of antioxidant enzymes (CAT by 1.18-5.83%, SOD by 1.47-17.8%, and GSH by 11.3-82.1%). Additionally, there was an increase in red cell distribution width (RDW) (from 4.61 to 25.19%) and in comet assay parameters such as Tail Length, (from 6.16 to 10.81 µm), Tail Moment, (from 1.17 to 2.46 µm), and percentage of DNA in tail length (DNA%) (from 9.58 to 17.32%) in all groups exposed to acute doses of radiation ranging from 5 to 50 mSv, respectively. This emphasizes the ascending harmful effect with the increased acute thermal neutron doses. The values of the introduced factor of radio adaptive response for all markers under study reveal that the lower priming dose promotes a higher adaptation response and vice versa. Ultimately, the results indicate significant variations in DNA%, SOD enzyme levels, EPR intensity, total Hb concentration, and RDWs, suggesting their potential use as biomarkers for acute thermal neutron dosimetry. Further research is necessary to validate these measurements as biodosimetry for radiation exposure, including investigations involving the response impact of RAR with varied challenge doses and post-irradiation behavior.

Asunto(s)

Biomarcadores , Neutrones , Animales , Ratas , Masculino , Biomarcadores/metabolismo , Superóxido Dismutasa/metabolismo , Peroxidación de Lípido/efectos de la radiación , Radiometría/métodos , Relación Dosis-Respuesta en la Radiación , Daño del ADN/efectos de la radiación , Adaptación Fisiológica/efectos de la radiación , Catalasa/metabolismo , Glutatión/metabolismo , Glutatión/sangre , Ensayo Cometa , Estrés Oxidativo/efectos de la radiación , Espectroscopía de Resonancia por Spin del Electrón/métodos

RESUMEN

We studied the molecular mechanisms of cross-adaptation to ionizing radiation (1 Gy) of lymphocytes isolated from rats subjected to emotional stress. The effects of chronic (CES; various types of stress exposure) and acute (AES; forced swimming) emotional stress in rats on indicators of oxidative stress, cell death, and levels of NRF2 and NOX4 proteins involved in the development of the adaptive response were analyzed in isolated lymphocytes. It was found that stress induced an adaptive response in rat lymphocytes and triggered processes similar to the adaptive response induced by low doses of ionizing radiation: an increase in the level of oxidized DNA and cell death, as well as an increase in the content of NOX4 and NRF2 proteins. In animals subjected to emotional stress, suppressed DNA oxidation in response to irradiation, reduced levels of protective factor NRF2, as well as lymphocyte death were observed.

Asunto(s)

Linfocitos , Factor 2 Relacionado con NF-E2 , Estrés Oxidativo , Radiación Ionizante , Estrés Psicológico , Animales , Linfocitos/efectos de la radiación , Linfocitos/metabolismo , Ratas , Factor 2 Relacionado con NF-E2/metabolismo , Factor 2 Relacionado con NF-E2/genética , Estrés Psicológico/metabolismo , Masculino , Estrés Oxidativo/efectos de la radiación , Ratas Wistar , Adaptación Fisiológica/efectos de la radiación , NADPH Oxidasa 4/metabolismo , NADPH Oxidasa 4/genética , Daño del ADN/efectos de la radiación

RESUMEN

Plants face a wide range of biotic and abiotic stress conditions, which are further intensified by climate change. Among these stressors, increased irradiation in terms of intensity and wavelength range can lead to detrimental effects, such as chlorophyll degradation, destruction of the PSII reaction center, generation of ROS, alterations to plant metabolism, and even plant death. Here, we investigated the responses of two citrus genotypes, Citrus macrophylla (CM), and Troyer citrange (TC) to UV-B light-induced stress, by growing plants of both genotypes under control and UV-B stress conditions for 5 days to evaluate their tolerance mechanisms. TC seedlings had higher sensitivity to UV-B light than CM seedlings, as they showed more damage and increased levels of oxidative harm (indicated by the accumulation of MDA). In contrast, CM seedlings exhibited specific adaptive mechanisms, including accumulation of higher levels of proline under stressful conditions, and enhanced antioxidant capacity, as evidenced by increased ascorbate peroxidase activity and upregulation of the CsAPX2 gene. Phytohormone accumulation patterns were similar in both genotypes, with a decrease in ABA content in response to UV-B light. Furthermore, expression of genes involved in light perception and response was specifically affected in the tolerant CM seedlings, which exhibited higher expression of CsHYH/CsHY5 and CsRUP1-2 genes. These findings underscore the importance of the antioxidant system in citrus plants subjected to UV-B light-induced stress and suggest that CsHYH/CsHY5 and CsRUP1-2 could be considered genes associated with tolerance to such challenging conditions.

Asunto(s)

Antioxidantes , Citrus , Prolina , Plantones , Rayos Ultravioleta , Citrus/efectos de la radiación , Citrus/genética , Citrus/fisiología , Citrus/metabolismo , Prolina/metabolismo , Antioxidantes/metabolismo , Plantones/efectos de la radiación , Plantones/fisiología , Plantones/genética , Plantones/metabolismo , Estrés Fisiológico , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Genotipo , Reguladores del Crecimiento de las Plantas/metabolismo , Estrés Oxidativo/efectos de la radiación , Adaptación Fisiológica/efectos de la radiación , Adaptación Fisiológica/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética

RESUMEN

The phytohormone jasmonate (JA) coordinates stress and growth responses to increase plant survival in unfavorable environments. Although JA can enhance plant UV-B stress tolerance, the mechanisms underlying the interaction of UV-B and JA in this response remain unknown. In this study, we demonstrate that the UV RESISTANCE LOCUS 8 - TEOSINTE BRANCHED1, Cycloidea and PCF 4 - LIPOXYGENASE2 (UVR8-TCP4-LOX2) module regulates UV-B tolerance dependent on JA signaling pathway in Arabidopsis thaliana. We show that the nucleus-localized UVR8 physically interacts with TCP4 to increase the DNA-binding activity of TCP4 and upregulate the JA biosynthesis gene LOX2. Furthermore, UVR8 activates the expression of LOX2 in a TCP4-dependent manner. Our genetic analysis also provides evidence that TCP4 acts downstream of UVR8 and upstream of LOX2 to mediate plant responses to UV-B stress. Our results illustrate that the UV-B-dependent interaction of UVR8 and TCP4 serves as an important UVR8-TCP4-LOX2 module, which integrates UV-B radiation and JA signaling and represents a new UVR8 signaling mechanism in plants.

Asunto(s)

Proteínas de Arabidopsis , Arabidopsis , Ciclopentanos , Regulación de la Expresión Génica de las Plantas , Oxilipinas , Rayos Ultravioleta , Arabidopsis/efectos de la radiación , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Transducción de Señal/efectos de la radiación , Proteínas Cromosómicas no Histona/metabolismo , Proteínas Cromosómicas no Histona/genética , Lipooxigenasa/metabolismo , Lipooxigenasa/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Unión Proteica/efectos de la radiación , Adaptación Fisiológica/efectos de la radiación , Adaptación Fisiológica/genética , Núcleo Celular/metabolismo , Lipooxigenasas

RESUMEN

PURPOSE: To deepen our knowledge on the effects of high levels of indoor radon exposure, we assessed the frequencies of unstable and stable chromosome aberrations and micronucleus (MN), as well as the concentration of an endogenous antioxidant (catalase, CAT), in blood samples of individuals chronically exposed to high indoor radon concentrations in Indonesia (Tande-Tande sub-village, Mamuju, West Sulawesi). Moreover, we also investigated the occurrence of a radio-adaptive response (RAR) in Tande-Tande sub-village inhabitants using the G2 MN assay. MATERIALS AND METHODS: The frequencies of dicentric (DC), acentric (AF), ring (R), and translocation (Tr) chromosomes in Tande-Tande inhabitants were compared to those in people living in a reference area with low levels of indoor radon levels (Topoyo village, Indonesia). The number of MN per 1000 binucleated cells (BNC) and CAT concentration per total protein was quantified and compared between groups. Lastly, we irradiated (2 Gy) phytohemagglutinin-stimulated samples in vitro and measured the frequency of MN to verify the occurrence of a RAR in Tande-Tande sub-village inhabitants. RESULTS AND CONCLUSION: The frequencies of DC, AF, and Tr did not differ between Tande-Tande inhabitants and control subjects (p = 0.350, 0.521, 0.597). The frequency of MN in Tande-Tande inhabitants was significantly lower than that in the control group (p = 0.006). Similarly, CAT concentration in Tande-Tande inhabitants was also significantly lower than that in the control population (p < 0.001). Significant negative correlations were identified for MN number and CAT concentration versus indoor radon concentration, annual effective dose, or cumulative dose both within groups and when all data were analyzed together. Our findings indicate that, despite the high indoor radon levels, Tande-Tande inhabitants are not under oxidative stress, since this group had lower CAT concentration and MN frequency than those in the control group. The negative correlation between MN frequency and indoor radon concentration, annual effective dose, and cumulative dose suggests the occurrence of an RAR phenomenon in Tande-Tande sub-village inhabitants. This interpretation is also supported by the results of the G2 MN assay, which revealed lower MN frequencies after in vitro irradiation of samples from Tande-Tande sub-village inhabitants than those in samples from the control group (p = 0.0069, for cumulative MN frequency; p = 0.0146, for radiation-induced MN only).

Asunto(s)

Catalasa , Aberraciones Cromosómicas , Micronúcleos con Defecto Cromosómico , Radón , Humanos , Masculino , Femenino , Adolescente , Adulto Joven , Adulto , Persona de Mediana Edad , Anciano , Indonesia , Aberraciones Cromosómicas/efectos de la radiación , Aberraciones Cromosómicas/estadística & datos numéricos , Micronúcleos con Defecto Cromosómico/estadística & datos numéricos , Catalasa/sangre , Radón/análisis , Radón/toxicidad , Dosis de Radiación , Adaptación Fisiológica/efectos de la radiación

RESUMEN

Iron (Fe) is an essential micronutrient whose availability is limiting in many soils. During Fe deficiency, plants alter the expression of many genes to increase Fe uptake, distribution, and utilization. In a genetic screen for suppressors of Fe sensitivity in the E3 ligase mutant bts-3, we isolated an allele of the bHLH transcription factor (TF) ILR3, ilr3-4 We identified a striking leaf bleaching phenotype in ilr3 mutants that was suppressed by limiting light intensity, indicating that ILR3 is required for phototolerance during Fe deficiency. Among its paralogs that are thought to be partially redundant, only ILR3 was required for phototolerance as well as repression of genes under Fe deficiency. A mutation in the gene-encoding PYE, a known transcriptional repressor under Fe deficiency, also caused leaf bleaching. We identified singlet oxygen as the accumulating reactive oxygen species (ROS) in ilr3-4 and pye, suggesting photosensitivity is due to a PSII defect resulting in ROS production. During Fe deficiency, ilr3-4 and pye chloroplasts retain normal ultrastructure and, unlike wild type (WT), contain stacked grana similar to Fe-sufficient plants. Additionally, we found that the D1 subunit of PSII is destabilized in WT during Fe deficiency but not in ilr3-4 and pye, suggesting that PSII repair is accelerated during Fe deficiency in an ILR3- and PYE-dependent manner. Collectively, our results indicate that ILR3 and PYE confer photoprotection during Fe deficiency to prevent the accumulation of singlet oxygen, potentially by promoting reduction of grana stacking to limit excitation and facilitate repair of the photosynthetic machinery.

Asunto(s)

Proteínas de Arabidopsis/fisiología , Arabidopsis/efectos de la radiación , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/fisiología , Hierro/metabolismo , Luz , Adaptación Fisiológica/efectos de la radiación , Arabidopsis/crecimiento & desarrollo , Arabidopsis/metabolismo , Arabidopsis/fisiología , Disponibilidad Biológica , Fotosíntesis , Brotes de la Planta/metabolismo , Oxígeno Singlete/metabolismo , Suelo

RESUMEN

INTRODUCTION: In the present study, the radioadaptive role of the immune system induced by low dose (LD) was investigated for its in vivo protective activity. MATERIALS AND METHODS: Quantitative analysis of cytokine gene expression was assessed for their in vivo activity in BALB/c mice. To evaluate the adaptive response induced by LD on the mice spleen lymphocyte, the cytokine interleukin (IL)-4, interferon (IFN)-γ, and transforming growth factor (TGF)-ß expression was measured by a real-time quantitative polymerase chain reaction. To verify the radioadaptive effect of LD, animals were preirradiated at 10 cGy from a 60 Co source and then challenge dose at 200 cGy was delivered. Independent sample student's t-test was employed to compare cytokine gene expression in radioadaptive (10 + 200 cGy), LD (10 cGy), high-dose (HD, 200 cGy), and control groups of animals. RESULTS: Following the HD, the cytokine gene expression of IFN-γ, IL-4, and TGF-ß was significantly decreased compared to the control group (P = 0.0001). However, TGF-ß expression was also decreased significantly in the LD and adaptive groups compared to the control group (P = 0.0001). IFN-γ/IL-4 ratio in the adaptive group was significantly decreased compared to the HD group (P = 0.0001). CONCLUSION: These results indicate that the immune system plays an important role for radioadaptive response induction by LD radiation to adjust the harmful effects of HD irradiation.

Asunto(s)

Adaptación Fisiológica/inmunología , Inmunidad Adaptativa/efectos de la radiación , Regulación de la Expresión Génica/efectos de la radiación , Adaptación Fisiológica/efectos de la radiación , Animales , Células Cultivadas , Relación Dosis-Respuesta en la Radiación , Regulación de la Expresión Génica/inmunología , Interferón gamma/genética , Interleucina-4/genética , Masculino , Ratones , Modelos Animales , Cultivo Primario de Células , Linfocitos T/inmunología , Linfocitos T/metabolismo , Linfocitos T/efectos de la radiación , Factor de Crecimiento Transformador beta/genética , Irradiación Corporal Total

RESUMEN

Multi-modal treatment of non-metastatic locally advanced rectal adenocarcinoma (LARC) includes chemotherapy, radiation, and life-altering surgery. Although highly effective for local cancer control, metastatic failure remains significant and drives rectal cancer-related mortality. A consistent observation of this tri-modality treatment paradigm is that histologic response of the primary tumor to neoadjuvant treatment(s), which varies across patients, predicts overall oncologic outcome. In this chapter, we will examine this treatment response heterogeneity in the context of evolutionary dynamics. We hypothesize that improved understanding of eco-evolutionary pressures rendering small cancer cell populations vulnerable to extinction may influence treatment strategies and improve patient outcomes. Applying effective treatment(s) to cancer populations causes a "race to extinction." We explore principles of eco-evolutionary extinction in the context of these small cancer cell populations, evaluating how treatment(s) aim to eradicate the cancer populations to ultimately result in cure. In this chapter, we provide an evolutionary rationale for limiting continuous treatment(s) with the same agent or combination of agents to avoid selection of resistant cancer subpopulation phenotypes, allowing "evolutionary rescue." We draw upon evidence from nature demonstrating species extinction rarely occurring as a single event phenomenon, but rather a series of events in the slide to extinction. We posit that eradicating small cancer populations, similar to small populations in natural extinctions, will usually require a sequence of different external perturbations that produce negative, synergistic dynamics termed the "extinction vortex." By exploiting these unique extinction vulnerabilities of small cancer populations, the optimal therapeutic sequences may be informed by evolution-informed strategies for patients with LARC.

Asunto(s)

Adenocarcinoma/patología , Evolución Clonal/fisiología , Terapia Neoadyuvante/efectos adversos , Neoplasias del Recto/patología , Adaptación Fisiológica/efectos de los fármacos , Adaptación Fisiológica/efectos de la radiación , Adenocarcinoma/terapia , Animales , Quimioterapia Adyuvante/efectos adversos , Evolución Clonal/efectos de los fármacos , Evolución Clonal/efectos de la radiación , Progresión de la Enfermedad , Humanos , Radioterapia/efectos adversos , Neoplasias del Recto/terapia

RESUMEN

The phenotypic plasticity of plants in response to change in their light environment, and in particularly, to shade is a schoolbook example of ecologically relevant phenotypic plasticity with evolutionary adaptive implications. Epigenetic variation is known to potentially underlie plant phenotypic plasticity. Yet, little is known about its role in ecologically and evolutionary relevant mechanisms shaping the diversity of plant populations in nature. Here we used a reference-free reduced representation bisulfite sequencing method for non-model organisms (epiGBS) to investigate changes in DNA methylation patterns across the genome in snapdragon plants (Antirrhinum majus L.). We exposed plants to sunlight versus artificially induced shade in four highly inbred lines to exclude genetic confounding effects. Our results showed that phenotypic plasticity in response to light versus shade shaped vegetative traits. They also showed that DNA methylation patterns were modified under light versus shade, with a trend towards global effects over the genome but with large effects found on a restricted portion. We also detected the existence of a correlation between phenotypic and epigenetic variation that neither supported nor rejected its potential role in plasticity. While our findings imply epigenetic changes in response to light versus shade environments in snapdragon plants, whether these changes are directly involved in the phenotypic plastic response of plants remains to be investigated. Our approach contributed to this new finding but illustrates the limits in terms of sample size and statistical power of population epigenetic approaches in non-model organisms. Pushing this boundary will be necessary before the relationship between environmentally induced epigenetic changes and phenotypic plasticity is clarified for ecologically relevant mechanisms with evolutionary implications.

Asunto(s)

Adaptación Fisiológica/genética , Antirrhinum/genética , Metilación de ADN/genética , Epigénesis Genética/genética , Adaptación Fisiológica/efectos de la radiación , Antirrhinum/efectos de la radiación , Metilación de ADN/efectos de la radiación , Epigénesis Genética/efectos de la radiación , Variación Genética/efectos de la radiación , Fenotipo , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Luz Solar

RESUMEN

Vascular plants use carotenoids and chlorophylls a and b to harvest solar energy in the visible region (400-700 nm), but they make little use of the far-red (FR) light. Instead, some cyanobacteria have developed the ability to use FR light by redesigning their photosynthetic apparatus and synthesizing red-shifted chlorophylls. Implementing this strategy in plants is considered promising to increase crop yield. To prepare for this, a characterization of the FR light-induced changes in plants is necessary. Here, we explore the behaviour of Arabidopsis thaliana upon exposure to FR light by following the changes in morphology, physiology and composition of the photosynthetic complexes. We found that after FR-light treatment, the ratio between the photosystems and their antenna size drastically readjust in an attempt to rebalance the energy input to support electron transfer. Despite a large increase in PSBS accumulation, these adjustments result in strong photoinhibition when FR-adapted plants are exposed to light again. Crucially, FR light-induced changes in the photosynthetic membrane are not the result of senescence, but are a response to the excitation imbalance between the photosystems. This indicates that an increase in the FR absorption by the photosystems should be sufficient for boosting photosynthetic activity in FR light.

Asunto(s)

Adaptación Fisiológica/efectos de la radiación , Arabidopsis/efectos de la radiación , Luz , Arabidopsis/fisiología , Clorofila/metabolismo , Fluorescencia , Complejos de Proteína Captadores de Luz/efectos de la radiación , Fotosíntesis/efectos de la radiación , Complejo de Proteína del Fotosistema I/efectos de la radiación , Complejo de Proteína del Fotosistema II/efectos de la radiación , Hojas de la Planta/efectos de la radiación , Tilacoides/efectos de la radiación

RESUMEN

Diverse algae of the red lineage possess chlorophyll a-binding proteins termed LHCR, comprising the PSI light-harvesting system, which represent an ancient antenna form that evolved in red algae and was acquired through secondary endosymbiosis. However, the function and regulation of LHCR complexes remain obscure. Here we describe isolation of a Nannochloropsis oceanica LHCR mutant, named hlr1, which exhibits a greater tolerance to high-light (HL) stress compared to the wild type. We show that increased tolerance to HL of the mutant can be attributed to alterations in PSI, making it less prone to ROS production, thereby limiting oxidative damage and favoring growth in HL. HLR1 deficiency attenuates PSI light-harvesting capacity and growth of the mutant under light-limiting conditions. We conclude that HLR1, a member of a conserved and broadly distributed clade of LHCR proteins, plays a pivotal role in a dynamic balancing act between photoprotection and efficient light harvesting for photosynthesis.

Asunto(s)

Adaptación Fisiológica/genética , Proteínas de Unión a Clorofila/metabolismo , Luz/efectos adversos , Complejo de Proteína del Fotosistema I/metabolismo , Estramenopilos/fisiología , Adaptación Fisiológica/efectos de la radiación , Clorofila A/metabolismo , Proteínas de Unión a Clorofila/genética , Proteínas de Unión a Clorofila/aislamiento & purificación , Mutación , Fotosíntesis/genética , Fotosíntesis/efectos de la radiación , Complejo de Proteína del Fotosistema I/genética , Estramenopilos/efectos de la radiación

RESUMEN

The phenomenon of a massive vertebral deformity was recorded in the radiating Labeobarbus assemblage from the middle reaches of the Genale River (south-eastern Ethiopia, East Africa). Within this sympatric assemblage, five trophic morphs-generalized, lipped, piscivorous and two scraping feeders-were reported between 1993 and 2019. In 2009, a new morph with prevalence of ~10% was discovered. The new morph, termed 'short', had an abnormally shortened vertebral column and a significantly deeper body. This type of deformity is common in farmed Atlantic salmon and other artificially reared fish, but is rare in nature. In the Genale Labeobarbus assemblage, the deformity was present exclusively within the generalized and lipped morphs. The short morph had between seven and 36 deformed (compressed and/or fused) vertebrae. Their body depth was positively correlated with number of deformed vertebrae. In another collection in 2019, the short morph was still present at a frequency of 11%. Various environmental and genetic factors could contribute to the development of this deformity in the Genale Labeobarbus, but based on the available data, it is impossible to confidently identify the key factor(s). Whether the result of genetics, the environment, or both, this deep-bodied phenotype is assumed to be an anti-predator adaptation, as there is evidence of its selective advantage in the generalized morph. The Genale monstrosity is the first reported case of a massive deformity of the vertebral column in a natural population of African fishes.

Asunto(s)

Cyprinidae/anomalías , Cyprinidae/genética , Columna Vertebral/efectos de la radiación , Anomalías Inducidas por Radiación/epidemiología , Adaptación Fisiológica/genética , Adaptación Fisiológica/efectos de la radiación , África Oriental , Animales , Etiopía , Ríos , Columna Vertebral/metabolismo

RESUMEN

The chloroplast is a key organelle for photosynthesis and perceiving environmental information. GENOME UNCOUPLED 4 (GUN4) has been shown to be required for the regulation of both chlorophyll synthesis, reactive oxygen species (ROS) homeostasis and plastid retrograde signaling. In this study, we found that growth of the gun4 mutant was significantly improved under medium strong light (200 µmol photons m-2s-1) compared to normal light (100 µmol photons m-2s-1), in marked contrast to wild-type (WT). Further analysis revealed that GUN4 interacts with SIGNAL RECOGNITION PARTICLE 54 KDA SUBUNIT (SRP43) and SRP54. RNA-seq analysis indicated that the expression of genes for light signaling and the circadian clock is altered in gun4 compared with (WT). qPCR analysis confirmed that the expression of the clock genes CLOCK-RELATED 1 (CCA1), LATE ELONGATION HYPOCOTYL (LHY), TIMING OF CAB EXPRESSION 1 (TOC1) and PSEUDO RESPONSE REGULATOR 7 (PRR7) is significantly changed in the gun4 and srp54 mutants under normal and medium strong light conditions. These results suggest that GUN4 may coordinate the adaptation of plants to changing light conditions by regulating the biological clock, although it is not clear whether the effect is direct or indirect.

Asunto(s)

Adaptación Fisiológica/efectos de la radiación , Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiología , Arabidopsis/efectos de la radiación , Relojes Circadianos , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Luz , Plantones/fisiología , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Relojes Circadianos/genética , Ritmo Circadiano/genética , Ritmo Circadiano/efectos de la radiación , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Ontología de Genes , Homeostasis , Péptidos y Proteínas de Señalización Intracelular/genética , Modelos Biológicos , Mutación/genética , Fenotipo , Unión Proteica/efectos de la radiación , Especies Reactivas de Oxígeno/metabolismo , Plantones/crecimiento & desarrollo , Plantones/efectos de la radiación

RESUMEN

The yield potentiality of kharif rice is not completely used even under well-irrigated agro-ecosystem, mainly due to low irradiance by overcast cloud throughout the growing season in eastern India. We observed more than 50% yield reduction compared to the performance of 100 high-yield genotypes for consecutive three years both under open and 30-35% reduced light intensity, mainly by 34%, 25% and 12% reduction of panicle number, grains per panicle and test weight. As per the analysis of variance, genotypic variance explained 39% of the total yield-variation under shade with 58% heritability. Overall, the maintenance of equal panicle per plant in both open and shade has the highest association with shade tolerance. Purnendu, Sashi and Pantdhan19 showed less than 28% yield-reduction by maintenance or even by increasing grain numbers under shade and test weight. On the other hand, maintenance of an equal number of panicle under both situations was the key to the tolerance of Bhasamanik, Sasarang, Rudra and Swarnaprabha. As compared to open, we noticed the improvement of chlorophyll a and b under shade but saw a poor correlation with the shade tolerance index. Comparing the net photosynthesis rate (Pn) in eight genotypes, we found the best tolerant line ranked last with least Pn at low light intensity (400 µmol m-2 s-1). We also identified diverse parental combinations between newly identified shade tolerant and abiotic stress tolerant high-yielding rice lines following diversity analysis using 54 simple-sequence repeats. Thus, the selected tolerant lines from a large set of genotypes with different adjustment ability to keep up high yield under low light intensity can be used for physiological, molecular analysis as well as pyramiding of traits.

Asunto(s)

Adaptación Fisiológica/genética , Variación Genética , Repeticiones de Microsatélite/genética , Oryza/genética , Estrés Fisiológico/genética , Adaptación Fisiológica/efectos de la radiación , Clorofila A/metabolismo , Mapeo Cromosómico , Cromosomas de las Plantas/genética , Ecosistema , Genotipo , India , Luz , Oryza/clasificación , Oryza/metabolismo , Fenotipo , Fotosíntesis/genética , Fotosíntesis/efectos de la radiación , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Sitios de Carácter Cuantitativo/genética

RESUMEN

Differential inherent and acquired radioresistance of human lung cancer cells contribute to poor therapeutic outcome and tumor recurrence after radiotherapy. Inherent radioresistance of lung cancer cells is known to be associated with ROSLow cancer stem cells (CSCs). However, mechanism of acquired radioresistance in lung cancer cells is poorly understood. Here, we exposed human lung cancer cells (A549) to a cumulative dose of 40Gy and allowed the radioresistant (RR) survivors to divide and form macroscopic colonies after each fraction of 5Gy dose. The RR subline exhibited enrichment of cytosolic ROSHigh cells without specific increase in mitochondrial ROS levels. We found a concomitant increase in the expression of redox regulatory transcription factor Nrf2 and its dependent antioxidant genes in RR cells and cell cycle delay as compared to parental cells. The treatment of RR cells with Nrf2 inhibitor resulted in decreased clonogenic survival indicating their addiction to Nrf2 for metabolic adaptations under high levels of cytosolic ROS. A causal role of inherent ROS levels in conferring radioresistance was established by sorting ROSHigh and ROSLow populations from parental and RR cells. It was observed that ROSHigh population from both parental and RR cells exhibited radioresistance as observed by clonogenic assay. Interestingly, ROSHigh population of cells exhibited higher levels of cellular thiols in both parental and RR cells. Thus, our observations highlight presence of a novel subpopulation in lung cancer cells, which exhibits radioresistance by maintaining 'oxidative stress' and Nrf2 dependent metabolic adaptations. We also posit Nrf2 pathway as a druggable target for radiosensitization of RR A549 cells.

Asunto(s)

Adaptación Fisiológica/efectos de la radiación , Radioisótopos de Cobalto/química , Resistencia a Antineoplásicos/efectos de la radiación , Neoplasias Pulmonares/radioterapia , Estrés Oxidativo/efectos de la radiación , Células A549 , Antioxidantes/metabolismo , Apoptosis/efectos de la radiación , Relación Dosis-Respuesta en la Radiación , Regulación de la Expresión Génica/efectos de la radiación , Humanos , Factor 2 Relacionado con NF-E2/genética , Factor 2 Relacionado con NF-E2/metabolismo , Células Madre Neoplásicas/efectos de la radiación , Oxidación-Reducción , Tolerancia a Radiación , Especies Reactivas de Oxígeno/metabolismo , Especies Reactivas de Oxígeno/efectos de la radiación , Compuestos de Sulfhidrilo/metabolismo

RESUMEN

Organisms that inhabit the temperate zone exhibit various seasonal adaptive behaviors, including reproduction, hibernation, molting, and migration. Day length, known as photoperiod, is the most noise-free and widely used environmental cue that enables animals to anticipate the oncoming seasons and adapt their physiologies accordingly. Although less clear, some human traits also exhibit seasonality, such as birthrate, mood, cognitive brain responses, and various diseases. However, the molecular basis for human seasonality is poorly understood. Herein, we first review the underlying mechanisms of seasonal adaptive strategies of animals, including seasonal reproduction and stress responses during the breeding season. We then briefly summarize our recent discovery of signaling pathways involved in the winter depression-like phenotype in medaka fish. We believe that exploring the regulation of seasonal traits in animal models will provide insight into human seasonality and aid in the understanding of human diseases such as seasonal affective disorder (SAD).

Asunto(s)

Adaptación Fisiológica , Afecto/efectos de la radiación , Hormonas/fisiología , Luz , Reproducción/efectos de la radiación , Estaciones del Año , Adaptación Fisiológica/fisiología , Adaptación Fisiológica/efectos de la radiación , Afecto/fisiología , Animales , Humanos , Fotoperiodo , Reproducción/fisiología , Factores de Riesgo , Trastorno Afectivo Estacional/epidemiología , Trastorno Afectivo Estacional/etiología

RESUMEN

Exquisitely regulated plastid-to-nucleus communication by retrograde signaling pathways is essential for fine-tuning of responses to the prevailing environmental conditions. The plastidial retrograde signaling metabolite methylerythritol cyclodiphosphate (MEcPP) has emerged as a stress signal transduced into a diverse ensemble of response outputs. Here, we demonstrate enhanced phytochrome B protein abundance in red light-grown MEcPP-accumulating ceh1 mutant Arabidopsis (Arabidopsis thaliana) plants relative to wild-type seedlings. We further establish MEcPP-mediated coordination of phytochrome B with auxin and ethylene signaling pathways and uncover differential hypocotyl growth of red light-grown seedlings in response to these phytohormones. Genetic and pharmacological interference with ethylene and auxin pathways outlines the hierarchy of responses, placing ethylene epistatic to the auxin signaling pathway. Collectively, our findings establish a key role of a plastidial retrograde metabolite in orchestrating the transduction of a repertoire of signaling cascades. This work positions plastids at the zenith of relaying information coordinating external signals and internal regulatory circuitry to secure organismal integrity.

Asunto(s)

Proteínas de Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , Arabidopsis/metabolismo , Etilenos/metabolismo , Ácidos Indolacéticos/metabolismo , Fitocromo B/metabolismo , Adaptación Fisiológica/efectos de los fármacos , Adaptación Fisiológica/efectos de la radiación , Arabidopsis/efectos de los fármacos , Arabidopsis/efectos de la radiación , Proteínas de Arabidopsis/genética , Transporte Biológico/efectos de los fármacos , Transporte Biológico/efectos de la radiación , Vías Biosintéticas/efectos de los fármacos , Vías Biosintéticas/genética , Vías Biosintéticas/efectos de la radiación , Epistasis Genética/efectos de los fármacos , Epistasis Genética/efectos de la radiación , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Genes de Plantas , Hipocótilo/efectos de los fármacos , Hipocótilo/crecimiento & desarrollo , Hipocótilo/efectos de la radiación , Ácidos Indolacéticos/farmacología , Luz , Mutación/genética , Fitocromo B/genética , Transducción de Señal/efectos de los fármacos , Transducción de Señal/efectos de la radiación

RESUMEN

Purpose: Studying the relationship between epigenetic variability with different individual radiosensitivity and adaptive capacity.Material and method: Using a simple and convenient experimental model - maize seedlings with different germination terms and epigenetic patterns - the hypothesis was tested that homogeneous genetically but epigenetic different organisms have different radiosensitivity and radioadaptive capacity. Differences in the DNA methylation profiles of individual subpopulations of seedlings were used as a marker of epigenetic differences and the yield of chromosomal aberration was used as an indicator of DNA vulnerability and its changes under different UV-C irradiation modes. In two series of experiments involving а UV-C acute single and exposure according to the scheme 'adaptive - challenging', the investigation of possible biological importance of epigenetic polymorphism has been performed. The study used a cytogenetic analysis of the yield of chromosomal aberrations and restriction analysis followed by ITS-ISSR- PCR.Results: Significant differences have been established in chromosome aberration yield and DNA methylation profile in control and under UV-C exposure for seedlings of subpopulations differing in time of germination. The differences in the DNA methylation profiles and the yield of chromosomal aberrations in the control subpopulations of seedlings of different germination term indicate the influence of the DNA methylation profile on DNA damage by regular metabolic factors, such as thermal vibrations or reactive oxygen species (ROS). This phenomenon can be explained with different chromatin conformation determining structural or 'passive' resistance, which provides different DNA availability to damage. Methylation switching into de novo under different mode radiation exposure could become a marker of gene expression changes due to induced repair and protecting.Conclusions: The obtained data indicate the importance of epigenetic factors in determining the radio-resistance and adaptive capacity of organisms. It points out that the epigenetic mechanisms that determine the choice of the metabolic pattern also contribute to the individual radiosensitivity and adaptive capacity of the organisms. This contribution is determined by two ways. First, the DNA methylation profile affects the initial damage processes and secondly, the type of methylation switching into de novo is associated with the further development of protection and repair processes.

Asunto(s)

Adaptación Fisiológica/genética , Adaptación Fisiológica/efectos de la radiación , Epigénesis Genética/efectos de la radiación , Tolerancia a Radiación/genética , Cromosomas de las Plantas/genética , Cromosomas de las Plantas/efectos de la radiación , Metilación de ADN/genética , Metilación de ADN/efectos de la radiación , Germinación/genética , Germinación/efectos de la radiación , Plantones/genética , Plantones/fisiología , Plantones/efectos de la radiación , Zea mays/genética , Zea mays/crecimiento & desarrollo , Zea mays/efectos de la radiación

RESUMEN

KEY MESSAGE: MfLEA3 is involved in protection of catalase activity and confers multiple abiotic stress tolerance. Late embryogenesis abundant (LEA) proteins are involved in plant growth, development and abiotic stress tolerance. A member of group 3 LEA proteins from Medicago sativa subsp. falcata (L.) Arcang, MfLEA3, was investigated in the study. MfLEA3 transcript was induced in response to cold, dehydration, and abscisic acid (ABA), while the cold-induced transcript of MfLEA3 was blocked by pretreatment with inhibitor of ABA synthesis. Constitutive expression of MfLEA3 led to enhanced tolerance to cold, drought, and high-light stress in transgenic tobacco plants. Compared to accumulated reactive oxygen species (ROS) in the wild-type in response to treatments with low temperature, drought, and high light, ROS were not accumulated in transgenic plants. Superoxide dismutase, catalase (CAT), and ascorbate-peroxidase activities were increased in all plants after treatments with the above stresses, while higher CAT activity was maintained in transgenic plants compared with wild-type. However, transcript level of CAT-encoding genes including CAT1, CAT2, and CAT3 showed no significant difference between transgenic plants and wild-type, indicating that the higher CAT activity was not associated with its gene expression. ABA sensitivity and transcripts of several ABA and stress-responsive genes showed no difference between transgenic plant and wild-type, indicating that ABA signaling was not affected by constitutive expression of MfLEA3. The results suggest that MfLEA3 may be involved in the protection of CAT activity and confers multiple abiotic stress tolerance.

Asunto(s)

Adaptación Fisiológica , Frío , Sequías , Regulación de la Expresión Génica de las Plantas , Medicago/genética , Nicotiana/genética , Nicotiana/fisiología , Proteínas de Plantas/genética , Ácido Abscísico/farmacología , Adaptación Fisiológica/efectos de los fármacos , Adaptación Fisiológica/efectos de la radiación , Secuencia de Aminoácidos , Catalasa/genética , Catalasa/metabolismo , Clonación Molecular , Deshidratación , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Peróxido de Hidrógeno/metabolismo , Luz , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/efectos de la radiación , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , ARN Mensajero/genética , ARN Mensajero/metabolismo , Nicotiana/efectos de los fármacos , Nicotiana/efectos de la radiación

RESUMEN

UV-B constitutes a critical part of the sunlight reaching the earth surface. The homodimeric plant UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8) monomerizes in response to UV-B and induces photomorphogenic responses, including UV-B acclimation and tolerance. REPRESSOR OF UV-B PHOTOMORPHOGENESIS 1 (RUP1) and RUP2 are negative feedback regulators that operate by facilitating UVR8 ground state reversion through re-dimerization. Here we show that RUP1 and RUP2 are transcriptionally induced by cryptochrome photoreceptors in response to blue light, which is dependent on the bZIP transcriptional regulator ELONGATED HYPOCOTYL 5 (HY5). Elevated RUP1 and RUP2 levels under blue light enhance UVR8 re-dimerization, thereby negatively regulating UVR8 signalling and providing photoreceptor pathway cross-regulation in a polychromatic light environment, as is the case in nature. We further show that cryptochrome 1, as well as the red-light photoreceptor phytochrome B, contribute to UV-B tolerance redundantly with UVR8. Thus, photoreceptors for both visible light and UV-B regulate UV-B tolerance through an intricate interplay allowing the integration of diverse sunlight signals.

Asunto(s)

Adaptación Fisiológica , Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiología , Arabidopsis/efectos de la radiación , Proteínas Cromosómicas no Histona/metabolismo , Criptocromos/metabolismo , Fototransducción , Rayos Ultravioleta , Adaptación Fisiológica/efectos de la radiación , Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Hipocótilo/crecimiento & desarrollo , Hipocótilo/efectos de la radiación , Luz , Fototransducción/efectos de la radiación , Modelos Biológicos , Multimerización de Proteína/efectos de la radiación , ARN Mensajero/genética , ARN Mensajero/metabolismo , Plantones/metabolismo , Plantones/efectos de la radiación