Effects of nitrogen application on ammonium assimilation and microenvironment in the rhizosphere of drip-irrigated sunflower under plastic mulch.

This study investigated the effect of nitrogen application on the rhizosphere soil microenvironment of sunflower and clarified the relationship between ammonium assimilation and the microenvironment. In a field experiment high (HN, 190 kg/hm2), medium (MN, 120 kg/hm2) and low nitrogen (CK, 50 kg/hm2) treatments were made to replicate plots of sunflowers using drip irrigation. Metagenomic sequencing was used to analyze the community structure and functional genes involved in the ammonium assimilation pathway in rhizosphere soil. The findings indicated that glnA and gltB played a crucial role in the ammonium assimilation pathway in sunflower rhizosphere soil, with Actinobacteria and Proteobacteria being the primary contributors. Compared with CK treatment, the relative abundance of Actinobacteria increased by 15.57% under MN treatment, while the relative abundance decreased at flowering and maturation stages. Conversely, the relative abundance of Proteobacteria was 28.57 and 61.26% higher in the MN treatment during anthesis and maturation period, respectively, compared with the CK. Furthermore, during the bud stage and anthesis, the abundance of Actinobacteria, Proteobacteria, and their dominant species were influenced mainly by rhizosphere soil EC, ammonium nitrogen (NH4+-N), and nitrate nitrogen (NO3--N), whereas, at maturity, soil pH and NO3--N played a more significant role in shaping the community of ammonium-assimilating microorganisms. The MN treatment increased the root length density, surface area density, and root volume density of sunflower at the bud, flowering, and maturity stages compared to the CK. Moreover, root exudates such as oxalate and malate were positively correlated with the dominant species of Actinobacteria and Proteobacteria during anthesis and the maturation period. Under drip irrigation, applying 120 kg/hm2 of nitrogen to sunflowers effectively promoted the community structure of ammonium-assimilating microorganisms in rhizosphere soil and had a positive influence on the rhizosphere soil microenvironment and sunflower root growth.

Effect and environmental behaviour of microplastics in soil.

Soil microplastic pollution is currently a worldwide concern. Microplastics are organic pollutants that are abundant in the natural environment, are persistent and difficult to degrade and may endanger human health while harming the environment. This article offers a bibliometric analysis of the environmental behaviour of microplastics in soils, as well as a thorough statistical analysis of research goals and trends in this field. We conducted a thorough search of all relevant literature from 2012 to 2022 in the Web of Science core database. The data analysis shows that, starting in 2012, there has been an upward trend in the number of articles about soil microplastic pollution. It can also be seen that China is relatively ahead of the curve in this area of research, followed by the United Kingdom and the United States. This article also systematically describes the research hotspots in this field. The results show that the current research on soil microplastics is mainly focused on their identification, enrichment and toxicity, whereas studies on the migration and transformation of soil microplastics and the mechanism of interaction with other pollutants are still lacking. Our results provide ideas and prospects for future research in this field.

Infiltration and Water Use Efficiency of Maize Fields with Drip Irrigation and Biodegradable Mulches in the West Liaohe Plain, China.

Biodegradable mulches have the same temperature- and moisture-preservation effects as ordinary plastic mulches before degradation. After degradation, rainwater enters the soil through the damaged parts, improving precipitation utilization. Under drip irrigation with mulching, this study explores precipitation utilization of biodegradable mulches under different precipitation intensities and the effects of different biodegradable mulches on the yield and water use efficiency (WUE) of spring maize in the West Liaohe Plain, China. In this paper, in situ field observation experiments were conducted for three consecutive years from 2016 to 2018. Three types of white degradable mulch films were set up, with induction periods of 60 d (WM60), 80 d (WM80), and 100 d (WM100). Three types of black degradable mulch films were also used, with induction periods of 60 d (BM60), 80 d (BM80), and 100 d (BM100). Precipitation utilization, yield, and WUE under biodegradable mulches were studied, with ordinary plastic mulches (PM) and bare land (CK) set as controls. The results showed that as precipitation increased, the effective infiltration of precipitation decreased first and then increased. When precipitation reached 89.21 mm, plastic film mulching no longer affected precipitation utilization. Under the same precipitation intensity, the precipitation effective infiltration ratio increased as the damage to the biodegradable film increased. Still, the intensity of this increase gradually decreased as the damage increased. The highest yield and WUE were observed for the degradable mulch film with an induction period of 60 days in years with normal rainfall and for the degradable mulch film with an induction period of 100 days in dry years. In the West Liaohe Plain, maize planted under film receives drip irrigation. We recommend that growers select a degradable mulch film with a degradation rate of 36.64% and an induction period of approximately 60 days in years with normal rainfall, and a degradable mulch film with an induction period of 100 days in dry years.

ROCK inhibitor fasudil reduces the expression of inflammatory factors in LPS-induced rat pulmonary microvascular endothelial cells via ROS/NF-κB pathway.

BACKGROUND: Inflammation plays a major role in the pulmonary artery hypertension (PAH) and the acute lung injury (ALI) diseases. The common feature of these complications is the dysfunction of pulmonary microvascular endothelial cells (PMVECs). Fasudil, the only Rho kinase (ROCK) inhibitor used in clinic, has been proved to be the most promising new drug for the treatment of PAH, with some anti-inflammatory activity. Therefore, in the present study, the effect of fasudil on lipopolysaccharide (LPS)-induced inflammatory injury in rat PMVECs was investigated. METHODS: LPS was used to make inflammatory injury model of rat PMVECs. Thereafter, the mRNA and protein expression of pro-inflammatory factors was evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) assay respectively. Intracellular reactive oxygen species (ROS) levels were measured by the confocal laser scanning system. The activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and the content of malondialdehyde (MDA) were determined by using commercial kits according to the manufacturer's instructions. Western blot assay was used to detect the protein expression of nuclear factor kappa B (NF-κB) p65. RESULTS: Fasudil effectively prevented inflammatory injury induced by LPS, which is manifested by the decrease of pro-inflammatory cytokines interleukin-6 (IL-6) and monocyte chenotactic protein-1 (MCP-1). Meanwhile, fasudil dramatically reduced the levels of ROS and MDA, and also elevated the activities of SOD and GSH-Px. Furthermore, the nuclear translocation of NF-κB p65 induced by LPS was also suppressed by fasudil. Additionally, the ROS scavengers N-Acetylcysteine (N-Ace) was also found to inhibit the nuclear translocation of NF-κB and the mRNA expression of IL-6 and MCP-1 induced by LPS, which suggested that ROS was essential for the nuclear translocation of NF-κB. CONCLUSIONS: The present study revealed that fasudil reduced the expression of inflammatory factors, alleviated the inflammatory and oxidative damage induced by LPS in rat PMVECs via ROS-NF-κB signaling pathway.

Inhibition of the INa/K and the activation of peak INa contribute to the arrhythmogenic effects of aconitine and mesaconitine in guinea pigs.

Aconitine (ACO), a main active ingredient of Aconitum, is well-known for its cardiotoxicity. However, the mechanisms of toxic action of ACO remain unclear. In the current study, we investigated the cardiac effects of ACO and mesaconitine (MACO), a structurally related analog of ACO identified in Aconitum with undocumented cardiotoxicity in guinea pigs. We showed that intravenous administration of ACO or MACO (25 µg/kg) to guinea pigs caused various types of arrhythmias in electrocardiogram (ECG) recording, including ventricular premature beats (VPB), atrioventricular blockade (AVB), ventricular tachycardia (VT), and ventricular fibrillation (VF). MACO displayed more potent arrhythmogenic effect than ACO. We conducted whole-cell patch-clamp recording in isolated guinea pig ventricular myocytes, and observed that treatment with ACO (0.3, 3 µM) or MACO (0.1, 0.3 µM) depolarized the resting membrane potential (RMP) and reduced the action potential amplitude (APA) and durations (APDs) in a concentration-dependent manner. The ACO- and MACO-induced AP remodeling was largely abolished by an INa blocker tetrodotoxin (2 µM) and partly abolished by a specific Na+/K+ pump (NKP) blocker ouabain (0.1 µM). Furthermore, we observed that treatment with ACO or MACO attenuated NKP current (INa/K) and increased peak INa by accelerating the sodium channel activation with the EC50 of 8.36 ± 1.89 and 1.33 ± 0.16 µM, respectively. Incubation of ventricular myocytes with ACO or MACO concentration-dependently increased intracellular Na+ and Ca2+ concentrations. In conclusion, the current study demonstrates strong arrhythmogenic effects of ACO and MACO resulted from increasing the peak INa via accelerating sodium channel activation and inhibiting the INa/K. These results may help to improve our understanding of cardiotoxic mechanisms of ACO and MACO, and identify potential novel therapeutic targets for Aconitum poisoning.

Effects of straw biochar application on soil temperature, available nitrogen and growth of corn.

Straw biochar could improve the water holding capacity effectivity of salinized soil, increase soil fertili, enhance crop yield, reduce greenhouse gas emission, and mitigate climate change. The mechanism of using straw biochar for soil improvement is different under various climate and soil texture conditions. To explore the mechanism of using straw biochar to improve soil and its influence on crop yield in the typical arid and semi-arid, a large temperature difference between day and night, soil temperature at different depths, and physiological changes and crop yield of maize at different growth stages were studied. It is assumed that straw biochar can improve the properties of salinized soil including physicochemical indexes, and crop physiological index, stimulates the positive circulation between soil, vegetation, and microorganisms, and plays a role in improving soil quality. The results showed that biochar application increased the average soil temperature (T) by 2 °C and reduced day-night T differences. Application of 30 t/ha biochar increased the average maize leaf T by 2.2 °C and photosynthetic rate by 16.5%. Furthermore, the average transpiration rate doubled compared to control, and the chlorophyll value increased by 21%. The application of biochar improved the utilization rate of nitrogen fertilizer by enhancing ammonification. Biochar application caused a maximum overall yield increase of 11.9% compared to control treatment (CK). Therefore, these results provide a practical basis for improving weakly alkaline farmland soils in arid and semi-arid areas, and provide an effective method to potentially mitigate the environmental crisis and promote sustainable development in agriculture.

Protective effect of berberine on aconite­induced myocardial injury and the associated mechanisms.

Aconitum plants, which have analgesic, diuretic and anti­inflammatory effects, have been widely used to treat various types of disease. However, the apparent toxicity of Aconitum­derived agents, particularly in the cardiovascular system, has largely limited their clinical use. Thus, the present study investigated whether berberine (Ber), an isoquinoline alkaloid, may reduce myocardial injury induced by aconitine (AC) in rats and the underlying mechanisms. Rats (n=40) were randomly divided into four groups: Control, Chuan­wu and Chuan­wu + Ber (8 and 16 mg/kg doses). Electrocardiograms (ECG) of the rats were recorded and serum biomarkers of cardiac function [lactate dehydrogenase (LDH), creatine kinase (CK) and CK­MB] were assayed. Histopathological changes were assessed using myocardial tissue sectioning and hematoxylin and eosin staining. Additionally, the effects of Ber on AC­induced arrhythmias in rats were observed. The changes in ECG following AC perfusion were observed, and the types and onset time of arrhythmias were analyzed. Furthermore, the effects of Ber and AC on papillary muscle action potentials were observed. The results suggested that Ber ameliorated myocardial injury induced by Chuan­wu, which was indicated by reduced arrhythmias and decreased LDH, CK and CK­MB levels in serum. Furthermore, histological damage, including dilation of small veins and congestion, was also markedly attenuated by Ber. In addition, the occurrence of arrhythmias was significantly delayed, and the dosage of AC required to induce arrhythmias was also increased by Ber pretreatment. Additionally, AC­induced changes in action potential amplitude, duration of 30% repolarization and duration of 90% repolarization in the papillary muscle were attenuated by Ber. All of these results indicate that Ber had a preventive effect on acute myocardial injury induced by Chuan­wu and arrhythmias caused by AC, which may be associated with the inhibition of delayed depolarization and triggered activity caused by AC. Thus, combination treatment of Ber with Aconitum plants may be a novel strategy to prevent AC­induced myocardial injury in clinical practice.

Group A Streptococcus induces less p65 nuclear translocation and non-classical nuclear factor kappa B activation in macrophages, which possibly leads to a weaker inflammatory response.

OBJECTIVES: The aim of this study was to explore the pathogenic mechanism of group A Streptococcus (GAS) and to investigate how GAS evades phagocytosis by immune cells. METHODS: The classical inflammatory signaling pathway of macrophages infected with GAS was investigated by protein microarray, real-time PCR, Western blot, immunoprecipitation, and flow cytometry. RESULTS: GAS induced a lower level of inflammatory mediators in macrophages than either the Gram-positive Staphylococcus aureus or the Gram-negative Escherichia coli. Therefore, the conventional inflammatory signal pathway was investigated. It was found that GAS and S. aureus induced both toll-like receptor (TLR)2 and TLR4 expression, while Gram-negative E. coli only activated TLR4 in RAW264.7 cells. Although MyD88, the main adaptor protein, was activated by the three pathogens, there was no difference in MyD88 expression in macrophages. Nuclear factor kappa B (NF-κB) is the classical transcription factor of inflammatory signals, and the results of the present study showed that GAS, similar to E. coli, induced a weaker p65 nuclear translocation compared to S. aureus. Interestingly, GAS activated NF-κB by inducing p65-p52 heterodimer, but not the classical heterodimer of NF-κB (p65-p50), while E. coli activated NF-κB by inducing both p65-p50 and p65-p52 heterodimers. CONCLUSIONS: Compared to S. aureus and E. coli infection, GAS induced a weaker nuclear translocation and distinct combination of NF-κB subunits in macrophages, which probably leads to a weak inflammatory response.

iPSC-derived human cardiac progenitor cells improve ventricular remodelling via angiogenesis and interstitial networking of infarcted myocardium.

We investigate the effects of myocardial transplantation of human induced pluripotent stem cell (iPSC)-derived progenitors and cardiomyocytes into acutely infarcted myocardium in severe combined immune deficiency mice. A total of 2 × 10(5) progenitors, cardiomyocytes or cell-free saline were injected into peri-infarcted anterior free wall. Sham-operated animals received no injection. Myocardial function was assessed at 2-week and 4-week post-infarction by using echocardiography and pressure-volume catheterization. Early myocardial remodelling was observed at 2-week with echocardiography derived stroke volume (SV) in saline (20.45 ± 7.36 µl, P < 0.05) and cardiomyocyte (19.52 ± 3.97 µl, P < 0.05) groups, but not in progenitor group (25.65 ± 3.61 µl), significantly deteriorated as compared to sham control group (28.41 ± 4.41 µl). Consistently, pressure-volume haemodynamic measurements showed worsening chamber dilation in saline (EDV: 23.24 ± 5.01 µl, P < 0.05; ESV: 17.08 ± 5.82 µl, P < 0.05) and cardiomyocyte (EDV: 26.45 ± 5.69 µl, P < 0.05; ESV: 18.03 ± 6.58 µl, P < 0.05) groups by 4-week post-infarction as compared to control (EDV: 15.26 ± 2.96 µl; ESV: 8.41 ± 2.94 µl). In contrast, cardiac progenitors (EDV: 20.09 ± 7.76 µl; ESV: 13.98 ± 6.74 µl) persistently protected chamber geometry against negative cardiac remodelling. Similarly, as compared to sham control (54.64 ± 11.37%), LV ejection fraction was preserved in progenitor group from 2-(38.68 ± 7.34%) to 4-week (39.56 ± 13.26%) while cardiomyocyte (36.52 ± 11.39%, P < 0.05) and saline (35.34 ± 11.86%, P < 0.05) groups deteriorated early at 2-week. Improvements of myocardial function in the progenitor group corresponded to increased vascularization (16.12 ± 1.49/mm(2) to 25.48 ± 2.08/mm(2) myocardial tissue, P < 0.05) and coincided with augmented networking of cardiac telocytes in the interstitial space of infarcted zone.

iPSC-derived human mesenchymal stem cells improve myocardial strain of infarcted myocardium.

We investigated global and regional effects of myocardial transplantation of human induced pluripotent stem cell (iPSC)-derived mesenchymal stem cells (iMSCs) in infarcted myocardium. Acute myocardial infarction (MI) was induced by ligation of left coronary artery of severe combined immunodeficient mice before 2 × 10(5) iMSCs or cell-free saline were injected into peri-infarcted anterior free wall. Sham-operated animals received no injection. Global and regional myocardial function was assessed serially at 1-week and 8-week by segmental strain analysis by using two dimensional (2D) speckle tracking echocardiography. Early myocardial remodelling was observed at 1-week and persisted to 8-week with global contractility of ejection fraction and fractional area change in saline- (32.96 ± 14.23%; 21.50 ± 10.07%) and iMSC-injected (32.95 ± 10.31%; 21.00 ± 7.11%) groups significantly depressed as compared to sham control (51.17 ± 11.69%, P < 0.05; 34.86 ± 9.82%, P < 0.05). However, myocardial dilatation was observed in saline-injected animals (4.40 ± 0.62 mm, P < 0.05), but not iMSCs (4.29 ± 0.57 mm), when compared to sham control (3.74 ± 0.32 mm). Furthermore, strain analysis showed significant improved basal anterior wall strain (28.86 ± 8.16%, P < 0.05) in the iMSC group, but not saline-injected (15.81 ± 13.92%), when compared to sham control (22.18 ± 4.13%). This was corroborated by multi-segments deterioration of radial strain only in saline-injected (21.50 ± 5.31%, P < 0.05), but not iMSC (25.67 ± 12.53%), when compared to sham control (34.88 ± 5.77%). Improvements of the myocardial strain coincided with the presence of interconnecting telocytes in interstitial space of the infarcted anterior segment of the heart. Our results show that localized injection of iMSCs alleviates ventricular remodelling, sustains global and regional myocardial strain by paracrine-driven effect on neoangiogenesis and myocardial deformation/compliance via parenchymal and interstitial cell interactions in the infarcted myocardium.

The inhibitory effects of m-nisoldipine on the 5-hydroxytryptamine-induced proliferation of pulmonary artery smooth muscle cells via Ca2+ antagonism and antioxidant mechanisms.

The excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) plays a critical role in the development of pulmonary arterial hypertension. Recent studies indicate that Ca(2+) and reactive oxygen species are critically involved in the process of smooth muscle cell proliferation stimulated by mitogens, such as 5-hydroxytryptamine (5-HT). Because m-nisoldipine, a Ca(2+) channel blocker of the dihydropyridine class, possesses some calcium antagonistic and antioxidant properties, we investigated the effect of m-nisoldipine on PASMC proliferation. The results indicated that m-nisoldipine inhibited 5-HT-induced PASMC proliferation, evaluated by BrdU incorporation and the MTT assay, and this effect was associated with a decreased expression of proliferating cell nuclear antigen (PCNA). Flow cytometry analysis showed that m-nisoldipine blocked 5-HT-induced cell-cycle progression by arresting the cells in the G(0)/G(1) phase. Next, the production of reactive oxygen species and the levels of [Ca(2+)](i) in PASMCs were measured by laser scanning confocal microscopy; m-nisoldipine pretreatment attenuated the [Ca(2+)](i) elevation and the production of reactive oxygen species induced by 5-HT. In addition, m-nisoldipine significantly decreased the 5-HT-induced activation of extracellular signal-regulated kinase (ERK1/2) and c-Jun N-terminal kinase (JNK) and the subsequent c-fos and c-jun mRNA expression. Meanwhile, results also showed that N-acetylcysteine (a reactive oxygen species scavenger) suppressed the proliferation and the ERK1/2 and JNK activation induced by 5-HT. In summary, this study demonstrated that m-nisoldipine effectively suppressed the 5-HT-induced PASMC proliferation, ERK1/2 and JNK activation and subsequent c-fos and c-jun mRNA expression, all of which might be associated with the Ca(2+) antagonistic and antioxidant properties of m-nisoldipine.

[Effect of m-nisoldipine on the Ca2+/CaM/CaN signal pathway in 5-HT-induced proliferation of rat PASMCs].

This study is to explore the activation of the Ca2+/CaM/CaN signal pathway in 5-HT-induced proliferation of rat pulmonary artery smooth muscle cells (PASMCs) and the inhibitory effect of m-nisoldipine (m-Nis) on this pathway. PASMCs were cultured with the explant technique. The proliferation of PASMCs was evaluated by MTT assay. Confocal microscopy was used to measure the change of [Ca2+]i. The mRNA expression of CaM and CaN was evaluated by RT-PCR and the activity of CaN was measured according to the instruction of kits. The results of MTT assay suggested that 5-HT (1 micromol x L(-1)) significantly induced the proliferation of rat PASMCs (P < 0.01), which was inhibited obviously by m-Nis (P < 0.05 or P < 0.01). Similarly, m-Nis inhibited 5-HT-induced elevation of [Ca2+]i (P < 0.01). The mRNA expression of CaM, CaN and the activation of CaN were also inhibited by m-Nis at different degrees (P < 0.05 or P < 0.01). Thus, the results of this study suggested that Ca2+/CaM/CaN signal pathway played an important role in 5-HT-induced proliferation of rat PASMCs, the inhibition of m-Nis on proliferation of rat PASMCs may be related to the blockage of Ca2+/CaM/CaN signal pathway by inhibiting the elevation of [Ca2+]i.

Fasudil hydrochloride hydrate, a Rho-kinase inhibitor, suppresses 5-hydroxytryptamine-induced pulmonary artery smooth muscle cell proliferation via JNK and ERK1/2 pathway.

Excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) plays a critical role in the development of pulmonary artery hypertension, and inhibition of PASMC proliferation has been shown to be beneficial to patients with this disease. Recent studies indicate that Rho/ROCK is critically involved in the proliferation of smooth muscle cells. However, the signal transduction of Rho/ROCK and its downstream signaling are not fully understood. In the present study, we investigated the antiproliferation effect of fasudil hydrochloride hydrate, a Rho-kinase inhibitor, on rat PASMC proliferation, and the possible relation of Rho/ROCK to ERK, JNK pathways. The results indicate that fasudil effectively inhibited 5-HT-induced PASMC proliferation, as evaluated by MTT assay and protein expression of proliferating cell nuclear antigen. Flow cytometry analysis showed that fasudil markedly blocked 5-HT-induced cell-cycle progression by arresting the cells in the G(0)/G(1) phase. Consistently, 5-HT-induced ROCK-1 mRNA expression and MYPT-1 phosphorylation were markedly suppressed by fasudil. In addition, fasudil significantly decreased 5-HT-induced JNK activation, ERK translocation to the nucleus and subsequent c-fos and c-jun expression. Taken together, these results indicate that Rho/ROCK is essential for PASMC proliferation produced by 5-HT. Fasudil effectively suppressed 5-HT-induced PASMC proliferation and cell-cycle progression, which was associated with inhibition of JNK activation, ERK translocation to nucleus and subsequent c-fos and c-jun expression.

m-Nisoldipine attenuates monocrotaline-induced pulmonary hypertension by suppressing 5-HT/ERK MAPK pathway.

Effect of new calcium antagonist m-nisoldipine (m-Nis) on MCT-induced PH in rats and its mechanisms were investigated. Rats were injected with a single dose (60 mg x kg(-1)) of MCT subcutaneously to induce PH. Pulmonary haemodynamic measurement and lung tissue morphological investigations were undertaken. The MDA production and SOD activity in the serum were tested. PCNA, ERK1 and p-ERK expressions were analyzed by Western blotting. The expressions of 5-HT and PCNA were observed with immunohistochemistry. Results suggested that the PAP, right ventricular index and the degree of muscularization of small pulmonary artery were elevated markedly in MCT group, which was attenuated by m-Nis treatment. A significant reduction in MDA production and an increase in the SOD activity in the serum were also observed in all three m-Nis groups. The number of PCNA and 5-HT positive smooth muscle cells increased significantly in MCT group, and m-Nis treatment attenuated the expression obviously. Western blotting results suggested that the protein expression of PCNA and the ratio of p-ERK/ ERK1 increased markedly in MCT group and decreased by m-Nis. In conclusion, m-Nis protected against MCT-induced PH by decreasing PAP, right ventricular index, PAMSCs proliferation and pulmonary artery remodelling, which may be related to the reduction of 5-HT and the suppression of the ERK/MAPK signal pathway.