Deciphering the dual role of persistent luminescence materials: Toxicity and photoreception effects on rice development.

Studies on the toxicity of micro- and nanomaterials in plants have primarily focused on their intrinsic effects. However, there is often oversight when considering the potential perceptual responses that plants may exhibit in response to these materials. In this investigation, we assessed the impact of three commercially available persistent luminescence materials (PLMs) that emit red, green, or blue light under various environmental conditions. We subjected rice (Oryza sativa L.), a short-day plant, to nine distinct treatments, including exposure to particles in isolation, their nocturnal afterglow, or a combination of both. We thoroughly examined rice seedling morphology, photosynthesis patterns, metabolite dynamics, and flowering gene expression to determine the biological responses of plants to these particles. These findings demonstrated that PLMs stably interact with rice, and their emitted afterglow precisely matches the perceptual bandwidth of rice photoreceptors. Notably, the nocturnal afterglow from the red and blue PLMs enhanced the vegetative growth of rice seedlings while inhibiting their reproductive development. The blue PLMs exhibited the most pronounced positive effects, while the red PLMs exhibited inhibitory effects. When exposed to a combination of red and blue PLMs, rice displays enhanced growth and development. The observed alterations in the expression patterns of genes responsible for flowering supported these effects. We concluded that PLMs influence rice growth and development due to their inherent properties and intermittent illumination during dark periods. Both factors collectively shape rice growth and development.

A modified cultivation strategy to enhance biomass production and lipid accumulation of Tetradesmus obliquus FACHB-14 with copper stress and light quality induction.

In this study, a two-stage culture strategy was refined to concurrently enhance the growth and lipid accumulation of Tetradesmus obliquus. The results unveiled that, during the initial stage, the optimal conditions for biomass accumulation were achieved with 0.02 mg·L-1 Cu2+ concentration and red light. Under these conditions, biomass accumulation reached 0.628 g·L-1, marking a substantial 23.62 % increase compared to the control group. In the second stage, the optimal conditions for lipid accumulation were identified as 0.5 mg·L-1 Cu2+ concentration and red light, achieving 64.25 mg·g-1·d-1 and marking a 128.38 % increase over the control. Furthermore, the fatty acid analysis results revealed an 18.85 % increase in the saturated fatty acid content, indicating enhanced combustion performance of microalgae cultivated under the dual stress of red light and 0.5 mg·L-1 Cu2+. This study offers insights into the potential application of Tetradesmus obliquus in biofuel production.

Regulatory effects of silicon nanoparticles on the growth and photosynthesis of cotton seedlings under salt and low-temperature dual stress.

BACKGROUND: Silicon nanoparticles (SiO2-NPs) play a crucial role in plants mitigating abiotic stress. However, the regulatory mechanism of SiO2-NPs in response to multiple stress remains unclear. The objectives of this study were to reveal the regulatory mechanism of SiO2-NPs on the growth and photosynthesis in cotton seedlings under salt and low-temperature dual stress. It will provide a theoretical basis for perfecting the mechanism of crop resistance and developing the technology of cotton seedling preservation and stable yield in arid and high salt areas. RESULTS: The results showed that the salt and low-temperature dual stress markedly decreased the plant height, leaf area, and aboveground biomass of cotton seedlings by 9.58%, 15.76%, and 39.80%, respectively. While SiO2-NPs alleviated the damage of the dual stress to cotton seedling growth. In addition to reduced intercellular CO2 concentration, SiO2-NPs significantly improved the photosynthetic rate, stomatal conductance, and transpiration rate of cotton seedling leaves. Additionally, stomatal length, stomatal width, and stomatal density increased with the increase in SiO2-NPs concentration. Notably, SiO2-NPs not only enhanced chlorophyll a, chlorophyll b, and total chlorophyll content, but also slowed the decrease of maximum photochemical efficiency, actual photochemical efficiency, photochemical quenching of variable chlorophyll, and the increase in non-photochemical quenching. Moreover, SiO2-NPs enhanced the activities of ribulose-1,5-bisphosphate carboxylase/oxygenase and phosphoenolpyruvate carboxylase, improved leaf water potential, and decreased abscisic acid and malondialdehyde content. All the parameters obtained the optimal effects at a SiO2-NPs concentration of 100 mg L- 1, and significantly increased the plant height, leaf area, and aboveground biomass by 7.68%, 5.37%, and 43.00%, respectively. Furthermore, significant correlation relationships were observed between photosynthetic rate and stomatal conductance, stomatal length, stomatal width, stomatal density, chlorophyll content, maximum photochemical efficiency, actual photochemical efficiency, photochemical quenching of variable chlorophyll, and Rubisco activity. CONCLUSION: The results suggested that the SiO2-NPs improved the growth and photosynthesis of cotton seedlings might mainly result from regulating the stomatal state, improving the light energy utilization efficiency and electron transport activity of PSII reaction center, and inducing the increase of Rubisco activity to enhance carbon assimilation under the salt and low-temperature dual stress.

Low-frequency ultrasound and nitrogen limitation induced enhancement in biomass production and lipid accumulation of Tetradesmus obliquus FACHB-12.

The two-stage cultivation strategy was optimized in this study to simultaneously promote the growth and lipid accumulation of Tetradesmus obliquus. Results showed that the optimal dual-stress conditions were nitrogen concentration at 25 mg N·L-1 and low-frequency ultrasound at 200 Watt, 1 min, and 8 h interval. The biomass and lipid content of Tetradesmus obliquus were increased by 32.1% and 44.5%, respectively, comparing to the control, and the lipid productivity reached 86.97 mg-1·L-1·d-1 at the end of the cultivation period. The protein and photosynthetic pigment contents of microalgae decreased by 22.4% and 14.0% under dual stress comparing to the control environment. In addition, dual stress cultivation of microalgae presented higher level of antioxidant capacity to balance to oxidation level in microalgal cells. This study provides a new insight for microalgae growth and lipid accumulation with dual stress stimulation.

Proteome Responses to Individual Pathogens and Abiotic Conditions in Rice Seedlings.

Rice plants under field conditions experience various biotic and abiotic stresses and are adapted to survive using a molecular cross-talk of genes and their protein products based on the severity of a given stress. Seedlings of cultivated variety ASD16 (resistant to fungal disease, blast; tolerant to abiotic stress, salinity) were subjected to salt, drought, high temperature and low temperature stress as well as infection by Rhizoctonia solani and Xanthomonas oryzae pv. oryzae (causing reemerging diseases such as sheath blight and leaf blight), respectively, the sheath blight and bacterial leaf blight pathogens. Leaf proteome was analyzed using two-dimensional electrophoresis and differentially expressed proteins were identified using mass spectrometry. In addition to many other differentially expressed proteins, acidic endochitinase was found to be upregulated during fungal infection and drought treatment, and a germin-like protein upregulated during fungal infection and high temperature stress. These two proteins were further validated at the gene expression level using reverse transcription-PCR in dual stress experiments. Pot culture plants were subjected to fungal infection followed by drought and drought followed by fungal infection to validate chitinase gene expression. Similarly, plants subjected to fungal infections followed by high temperature stress and vice versa were used to validate the expression of germin-like protein-coding gene. The results of the present study indicate that chitinase and germin-like protein are potential targets for further exploration to develop rice plants resistant or tolerant to biotic and abiotic stresses.

Effects of psychological stress during exercise on markers of oxidative stress in young healthy, trained men.

PURPOSE: Those engaged in high stress occupations such as firefighters and military personnel are exposed to a variety of psychological and physiological stressors. The combination of mental and physical stress [i.e., dual stress challenges (DSC)] results in significant increases in stress hormones, which causes oxidative stress (OS) and contributes to elevated risk for cardiovascular disease. However, data are needed to determine the impact of DSC on markers of OS in exercise-trained individuals. METHOD: Fourteen healthy trained men aged 21-30 yrs. participated in a randomized, cross-over design to investigate the impact of DSC on blood markers of OS. The exercise alone condition (EA) consisted of 35 min of cycling at 60% V̇O2 peak. The DSC involved 20 min of mental stress challenges during exercise. Blood was sampled before exercise, as well as immediately, and 30 and 60 min after exercise and analyzed for glutathione (GSH), superoxide dismutase (SOD), hydrogen peroxide (H2O2) and advanced oxidation protein products (AOPP). RESULT: No significant treatment × time interactions were found. No time effects were noted for SOD, or H2O2; however, AOPP were reduced at 30 (p = .034) and 60 min post exercise (p = .006). GSH was reduced at 30 (p = .009) and 60 min post exercise (p = .031). CONCLUSION: These results indicate the OS response from DSC is not greater than that produced from EA in exercise trained men. Future work should investigate the impact of chronic resistance and endurance exercise training on OS resulting from DSC.

Aerobic fitness impacts sympathoadrenal axis responses to concurrent challenges.

The combination of mental and physical challenges can elicit exacerbated cardiorespiratory (CR) and catecholamine responses above that of a single challenge alone. PURPOSE: This study examined the effects of a combination of acute mental challenges and physical stress on cardiorespiratory and catecholamine responses. METHOD: Eight below-average fitness (LF VO2max = 36.58 ± 3.36 ml-1 kg-1 min-1) and eight above-average fitness (HF VO2max = 51.18 ± 2.09 ml-1 kg-1 min-1) participants completed an exercise-alone condition (EAC) session consisting of moderate-intensity cycling at 60% VO2max for 37 min, and a dual-challenge condition (DCC) that included concurrent participation in mental challenges while cycling. RESULT: The DCC resulted in increases in perceived workload, CR, epinephrine, and norepinephrine responses overall. HF participants had greater absolute CR and catecholamine responses compared to LF participants and quicker HR recovery after the dual challenge. CONCLUSION: These findings demonstrate that cardiorespiratory fitness does impact the effect of concurrent stressors on CR and catecholamine responses.

Comparison of depressive behaviors induced by three stress paradigms in rats.

Depression is a severe psychiatric disorder, which is a huge burden on both the individual and society as a whole. Neurobiological studies of depression on humans are limited by ethics. Animal models established by stressor stimulation are currently effective tools for the neurobiological study of depression. In this study, we comparatively analyzed behavioral heterogeneity, gender, and individual differences in animal models reflecting early life stress, adverse events in adulthood, or combined early life stress and stressful events in adulthood. Results demonstrated that these three different stressors induced dissimilar depressive behaviors. Maternal deprivation (MD) induced severe anhedonia. Chronic unpredictable stress (CUPS) induced the most severe decrease in desperation behavior, moderate anhedonia, and moderate loss of interest in exploration of the surroundings. Dural stress (DS) exposure caused the most severe decline in interest in exploring the surroundings. Male rats all exhibited some form of depressive behavior after they were exposed to MD, CUPS and DS. In contrast, no depressive performance was observed in female rats after they were exposed to MD, and the CUPS only decreased the total distance the rats crawled in the open field test. Rats exhibited more obvious individual differences in floating time than in the vertical activity, total distance and sucrose preference rate when experiencing stress. Our study suggests that different stressors may induce different depression subtypes and that the observed differences in the prevalence of depression between genders in the clinic may be due to effect of psychosocial factors which affects humans more strongly than rats. Our study also suggests that individual difference is more obvious in desperation behaviors than that in exploratory interest and anhedonia when the individual experienced stress.

The dysregulation of hippocampal serotonin receptor 4 and let-7a were associated with dual stress-induced depression in rats / 中华行为医学与脑科学杂志

Objective To study the effect of dual stress on the behaviors and the expression of hippocampal let-7a and serotonin receptor 4(HTR4) in rats.Methods Newborn SD rats were randomly divided into dual stress group (DS,n=6) and control group (C,n=6).The DS rats were deprived of the mother care 6 hours per day from postnatal day 1 to 14 and then were exposed to chronic mild stress for 21 days from 10 weeks old,while the rats from C group received no experimental handle but husbandry care.Open field test,forced swimmiug test and sucrose consumption test were conducted to evaluate rats' depression-like behaviors at the age of thirteen weeks.The let-7a level in hippocampus was detected by real-time Polymerase Chain Reaction and the HTR4 protein level was measured by Western Blotting.Results In the open filed test,the rearing times of DS rats was shorter than that of C group((7.50±2.35) vs (19.00±5.73),P＜0.05).In the forced swimming test,the floating time of DS rats was longer than that of C group ((110.17 ± 1.72)s vs (70.33± 1.16)s,P＜ 0.05).In the sucrose c onsumption test,DS rats consumed less sucrose than rats from C group did((0.80±0.73) vs (0.52±0.26),P＜ 0.05).The protein level of hippocampal HTR-4 in DS group was lower than that of C group((1.44±0.38) vs (0.46±0.29),P＜0.01).The let-7a level in DS group was higher than that of C group((0.04±0.01) vs (1.58±0.27),P＜0.01).The Pearson correlation analysis revealed that the sucrose preference rate of rats were negatively and positively correlated with hippocampal let-7a and HTR4 level respectively(r=-0.653,P＜0.05; r=0.774,P＜0.01),and hippocampal let-7a level showed negative association with HTR4 protein level (r=-0.803,P＜0.01).Conclusion Dual stress can induce the depressive behaviors of rats and affect the expression of let-7a and HTR4 in hippocampus.Hippocampal HTR4 and let-7a might be involved in determining individual ability to experience pleasure in rats;and hippocampal let-7a may be involved in the regulation of HTR4 gene expression in rats.