Decoupling of nitrogen allocation and energy partitioning in rice after flowering.

Estimation of energy partitioning at leaf scale, such as fluorescence yield (ΦF) and photochemical yield (ΦP), is crucial to tracking vegetation gross primary productivity (GPP) at global scale. Nitrogen is an important participant in the process of light capture, electron transfer, and carboxylation in vegetation photosynthesis. However, the quantitative relationship between leaf nitrogen allocation and leaf energy partitioning remains unexplored. Here, a field experiment was established to explore growth stage variations in energy partitioning and nitrogen allocation at leaf scale using active fluorescence detection and photosynthetic gas exchange method in rice in the subtropical region of China. We observed a strongly positive correlation between the investment proportion of leaf nitrogen in photosynthetic system and ΦF during the vegetative growth stage. There were significant differences in leaf energy partitioning, leaf nitrogen allocation, and the relationship between ΦF and ΦP before and after flowering. Furthermore, flowering weakened the correlation between the investment proportion of leaf nitrogen in photosynthetic system and ΦF. These findings highlight the crucial role of phenological factors in exploring seasonal photosynthetic dynamics and carbon fixation of ecosystems.

Physiological dynamics dominate the relationship between solar-induced chlorophyll fluorescence and gross primary productivity along the nitrogen gradient in cropland.

Solar-induced chlorophyll fluorescence (SIF) has been found to be robustly correlated with gross primary productivity (GPP) based on satellite datasets. However, it is unclear whether nitrogen affects the relationship between SIF and GPP at the canopy scale. Here, seasonal dynamics of SIF, GPP, vegetation physiology and canopy structure were measured synchronously throughout growing season along the nitrogen gradient in a rice paddy of China's subtropical region. Our results found that the slope of SIF against GPP was not constant, showing an increasing trend from low to high nitrogen levels. The sensitivity of SIF to nitrogen was larger than that of GPP. Nitrogen enrichment versus deficiency had asymmetrical effects on the SIF-GPP relationship. The steeper slope of SIF against GPP under high nitrogen level was mainly attributed to the promotion of canopy fluorescence efficiency (ΦF) rather than the variation of canopy fluorescence escape probability (Fesc). These results emphasize the vital role of nitrogen in exploring mechanisms underlying SIF dynamics and decoding GPP from SIF.

The Phenolic Compounds, Metabolites, and Antioxidant Activity of Propolis Extracted by Ultrasound-Assisted Method.

The influences of ultrasound-assisted, pharmacopeia, and supercritical fluid extraction methods on bioactive compounds and biological activities of propolis were evaluated. Results showed that propolis extracted by ultrasound-assisted method contained more phenolic compounds, and showed the highest total phenolic content (245.84 ± 6.41 mg GAE/g DW), total flavonoids content (198.82 ± 5.74 mg RE/g DW), and stronger in vitro antioxidant activity (DPPH·: 1.03 ± 0.04 mmol Trolox/g DW, ABTS+·: 2.19 ± 0.05 mmol Trolox/g DW, and FRAP: 1.48 ± 0.12 mmol FeSO4 /g DW) than those of pharmacopoeia and supercritical fluid methods. A total of 36 phenolic compounds were identified in propolis. Among them, quercetin, quercetin-3-methyl-ether, kaempferol, isorhamnetin, luteolin-methyl-ether, and quercetin-7-methyl-ether could only be found in ultrasound-assisted and pharmacopoeia methods. Moreover, the phenolic compounds had the similar metabolic pathways in rats and were mainly metabolized by sulfation and glucuronidation pathways. Additionally, ultrasonic-treated propolis have good in vivo antioxidant activity and could repair D-galactose-induced oxidative damage in rats. Therefore, ultrasound-assisted method could replace pharmacopeia method to be considered as bioactive compounds extraction from propolis, taking into consideration of yield, short extraction time, and high antioxidant activity.

[Synergic antidepressive effect of quercetin and Hypericum perforatum extract in mice].

OBJECTIVE: To explore the synergistic antidepressant effect of quercetin and hyperforin (HF, extracted from Hypericum perforatum). METHODS: Male ICR mice were divided into nine groups:blank control, positive control (Paroxetine, 10 mg/kg), quercetin groups (A: 5 mg/kg, B: 10 mg/kg, C: 20 mg/kg), Hypericum perforatum extract (HF 10 mg/kg),combination groups (A: quercetin 2.5 mg/kg + HF 5 mg/kg,B:quercetin 5 mg/kg + HF 5 mg/kg,C: quercetin 10 mg/kg + HF 5 mg/kg). All drugs were administered intragastrically. Reserpine reversal tests were used to compare the reversal effects of drugs on body temperature decline, eyelid ptosis and akinesia. Tail suspension test was used to compare immobility time in each group. RESULTS: Combination group B showed no significant difference (P>0.05) compared with combination group C in reserpine reversal tests and tail suspension test. However, its body temperature reversal effect was significantly higher (P<0.01) than that of quercetin group B, and its effect in shortening immobility time was stronger than that of HF 10 mg/kg group (P<0.05) and quercetin group B (P<0.01). CONCLUSION: The combination of quercetin and Hypericum perforatum extract in certain ratio has significant synergistic antidepressant effect in ICR mice.

[Comparison of seizure induced by different drugs in ICR Mice].

OBJECTIVE: To compare seizure induced by different epileptic drugs in ICR mice. METHODS: Male adult ICR mice were injected with pilocarpine (Pilo), kainic acid (KA) and pentylenetetrazole (PTZ) to induce status epilepticus (SE). After 2 h of SE, seizures were terminated by injection of diazepam. Mice were sacrificed and sectioned for assessment of neuronal cell death by Fluro-Jade B staining after 7 d and mossy fiber sprouting by Timm staining after 28 d, respectively. Spontaneous seizures were detected by video for 28 d. RESULTS: Pilo and KA induced typical SE in ICR mice, which was identical to those observed in rats and C57/BL6 mice. Timm staining showed evident mossy fiber sprouting in both Pilo and KA treated mice. The incidences of spontaneous seizure were 57.1% and 35.7% in Pilo and KA treated mice, respectively. Mice treated with PTZ represented kindling model. No mossy fiber sprouting and spontaneous seizures were observed. No cell death was detected in all three groups. CONCLUSION: Similar seizure pattern is observed in ICR mice as in rats and C57/BL6 mice. Both Pilo and KA model are the ideal models for chronic temporal lobe epilepsy. ICR mice can be widely used as a cheaper substitute in epilepsy research.