Root Reduction Caused Directly or Indirectly by High Application of Nitrogen Fertilizer Was the Main Cause of the Decline in Biomass and Nitrogen Accumulation in Citrus Seedlings.

Citrus is the largest fruit crop around the world, while high nitrogen (N) application in citrus orchards is widespread in many countries, which results not only in yield, quality and environmental issues but also slows down the establishment of citrus canopies in newly cultivated orchards. Thus, the objective of this study was to investigate the physiological inhibitory mechanism of excessive N application on the growth of citrus seedlings. A pot experiment with the citrus variety Orah (Orah/Citrus junos) at four N fertilization rates (0, 50, 100, and 400 mg N/kg dry soil, denoted as N0, N50, N100, and N400, respectively) was performed to evaluate the changes of root morphology, biomass, N accumulation, enzyme activities, and so on. The results showed that the N400 application significantly reduced the total biomass (from 14.24 to 6.95 g/Plant), N accumulation (from 0.65 to 0.33 g/Plant) and N use efficiency (92.69%) in citrus seedlings when compared to the N100 treatment. The partial least squares pathway model further showed that the decline of biomass and N accumulation by high N application were largely attributed to the reduction of root growth through direct and indirect effects (the goodness of fit under the model was 0.733.) rather than just soil N transformation and activity of root N uptake. These results are useful to optimize N management through a synergistic N absorption and utilization by citrus seedlings.

Integrated proteome and physiological traits reveal interactive mechanisms of new leaf growth and storage protein degradation with mature leaves of evergreen citrus trees.

The growth of fruit trees depends on the nitrogen (N) remobilization in mature tissues and N acquisition from the soil. However, in evergreen mature citrus (Citrus reticulata Blanco) leaves, proteins with N storage functions and hub molecules involved in driving N remobilization remain largely unknown. Here, we combined proteome and physiological analyses to characterize the spatiotemporal mechanisms of growth of new leaves and storage protein degradation in mature leaves of citrus trees exposed to low-N and high-N fertilization in the field. Results show that the growth of new leaves is driven by remobilization of stored reserves, rather than N uptake by the roots. In this context, proline and arginine in mature leaves acted as N sources supporting the growth of new leaves in spring. Time-series analyses with gel electrophoresis and proteome analysis indicated that the mature autumn shoot leaves are probably the sites of storage protein synthesis, while the aspartic endopeptidase protein is related to the degradation of storage proteins in mature citrus leaves. Furthermore, bioinformatic analysis based on protein-protein interactions indicated that glutamate synthetase and ATP-citrate synthetase are hub proteins in N remobilization from mature citrus leaves. These results provide strong physiological data for seasonal optimization of N fertilizer application in citrus orchards.

Analysis of the Development Trend in Forensic Odontology Based on CiteSpace.

OBJECTIVES: To realize the dynamic visualization of forensic odontology based on the bibliometrics methods, and capture the research hotspots and identify the future development trend. METHODS: Literature articles published from January 1995 to December 2020 were searched according to specific subject words in the core data set of Web of Science. The visualization analysis of publishing country, institution, discipline, author, co-cited journal and keywords was performed by CiteSpace 5.7.R5W software. RESULTS: The annual analysis of publications showed an upward trend of forensic odontology research literature year by year, with the number of annual publications more than 110 in the last five years. Developed countries were the main source of contributions and the average centrality was greater than 0.2. The research of forensic odontology involved multiple disciplines, including stomatology, biology, computer science and medical imaging, with a distinct interdisciplinary feature. A total of 115 nodes were obtained by keyword cluster analysis. The principal line of forensic odontology mainly included individual identification and age estimation and the emergence of hotspots was closely related to new technologies. Population-based odontology investigation, improvement of traditional dental age estimation method and dental age estimation based on new technology were popular research in forensic odontology. CONCLUSIONS: Developing countries urgently need to increase the focus on related research. It may be an important direction for the development of forensic odontology to establish and enrich the regional dental database, develop new odontology identification technology combined with frontier and high-end technology, and develop the identification program based on advanced information technology.

Integrated physiological, proteome and gene expression analyses provide new insights into nitrogen remobilization in citrus trees.

Nitrogen (N) remobilization is an important physiological process that supports the growth and development of trees. However, in evergreen broad-leaved tree species, such as citrus, the mechanisms of N remobilization are not completely understood. Therefore, we quantified the potential of N remobilization from senescing leaves of spring shoots to mature leaves of autumn shoots of citrus trees under different soil N availabilities and further explored the underlying N metabolism characteristics by physiological, proteome and gene expression analyses. Citrus exposed to low N had an approximately 38% N remobilization efficiency (NRE), whereas citrus exposed to high N had an NRE efficiency of only 4.8%. Integrated physiological, proteomic and gene expression analyses showed that photosynthesis, N and carbohydrate metabolism interact with N remobilization. The improvement of N metabolism and photosynthesis, the accumulation of proline and arginine, and delayed degradation of storage protein in senescing leaves are the result of sufficient N supply and low N remobilization. Proteome further showed that energy generation proteins and glutamate synthase were hub proteins affecting N remobilization. In addition, N requirement of mature leaves is likely met by soil supply at high N nutrition, thereby resulting in low N remobilization. These results provide insight into N remobilization mechanisms of citrus that are of significance for N fertilizer management in orchards.

Global reactive nitrogen loss in orchard systems: A review.

Orchards account for about 5% of the agricultural land in the world, however the amount of nitrogen (N) fertilizer input in orchards is relatively large. Little is known about N input and its impact in orchards at the global scale. Therefore, in this study we systematically evaluated reactive nitrogen (Nr) loss in global orchards. A meta-analysis of 97 studies reported from 2000 to 2021 from different countries showed that the mean global N fertilizer input in orchards was 303 kg N ha-1 yr-1, and the estimated emission factor (EF) of nitrous oxide (N2O) and ammonia (NH3) were 1.39% and 3.64%, respectively. Also, during the same period, orchard nitrate leaching factor (LF) reached 18.5%, and the runoff N loss factor (RF) and net fruit N removal factor (NRF) were estimated to be 2.75% and 5.31%, respectively. The apparent N balance of the global orchard system reached 68.4% of N input. N application increased the Nr loss in various pathways in the orchard. The N2O and NH3 emission and nitrate leaching were linearly correlated with N fertilizer application, and overuse of N resulted in substantial Nr loss. Regionally, the total Nr loss in developing countries was higher than developed countries. Average N input (405 kg N ha-1 yr-1) and Nr loss (102 kg N ha-1 yr-1) of orchards in Asia were the highest. The NH3 volatilization and runoff N loss of deciduous orchards were significantly higher than that of evergreen orchards. N application increased fruit yield, but excessive N input reduced the net fruit N removal (FNR). The results reported here fill an important knowledge gap of N balance analysis of orchards at a global scale and provided a framework for optimizing N management to achieve sustainable fruit production.

Nitrogen fertilization stimulates nitrogen assimilation and modifies nitrogen partitioning in the spring shoot leaves of citrus (Citrus reticulata Blanco) trees.

The spring shoot leaves are important sites of nitrogen (N) metabolism in citrus trees. Understanding the physiological and metabolic response of the spring shoot leaves under varying N fertilization is fundamental to the fertilization management in citrus orchards. Thus, the processes affecting N composition, the activities of N metabolism related enzymes, and the expression of relevant genes were explored in spring shoot leaves under four N levels (0, 207, 275, 413 g N tree-1 y-1, as N0, N207, N275, N413). The results showed that, compared with N0, N275 significantly increased total N by 24.81%, which was mainly attributed to enhancement of structural N by 30.92%, free amino acid N by 40.91% and nitrate N by 41.33%. The relative expression of nitrate reductase (NR) and glutamate dehydrogenase (GDH) under N275 increased by 19.32% and 73.48%, respectively, compared with that under N0 treatment. Compared with N0 treatment, the NR transcription level under N275 treatment increased by 381%. The relative transcription levels of NADP-GDH and GDH1 also increased with increasing N fertilization. However, compared with that under N275, the relative transcription of GDH2 under N413 treatment was inhibited. Therefore, the transcript abundance of NR, NADP-GDH,GDH1 and GDH2 affected the activities of NR and GDH and thereby contributed to the regulation of N composition in the leaves. In addition, the activities of glutamine synthetase and nitrite reductase were largely unaffected or even declined in the N207, N275 and N413 treatments compared with the N0. This study elucidated the mechanism of primary N metabolism and partitioning in citrus leaves and provided a theoretical basis for N management in citrus orchards.

Expression profile analysis reveals hub genes that are associated with immune system dysregulation in primary myelofibrosis.

OBJECTION: Primary myelofibrosis (PMF) is a familiar chronic myeloproliferative disease with an unfavorable prognosis. The effect of infection on the prognosis of patients with PMF is crucial. Immune system dysregulation plays a central role in the pathophysiology of PMF. To date, very little research has been conducted on the molecular mechanism of immune compromise in patients with PMF. METHODS: To explore potential candidate genes, microarray datasets GSE61629 and 26049 were obtained from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) between PMF patients and normal individuals were evaluated, gene function was measured and a series of hub genes were identified. Several significant immune cells were selected via cell type enrichment analysis. The correlation between hub genes and significant immune cells was determined. RESULTS: A total of 282 DEGs were found, involving 217 upregulated genes and 65 downregulated genes. Several immune cells were found to be reduced in PMF, such as CD4+ T cells, CD4+ Tems, CD4+ memory T cells. Gene Ontology (GO) enrichment analysis of DEGs reflected that most biological processes were associated with immune processes. Six hub genes, namely, HP, MPO, MMP9, EPB42, SLC4A1, and ALAS2, were identified, and correlation analysis revealed that these hub genes have a negative correlation with immune cell abundance. CONCLUSIONS: Taken together, the gene expression profile of whole blood cells in PMF patients indicated a battery of immune events, and the DEGs and hub genes might contribute to immune system dysregulation.

Soil type shapes the antibiotic resistome profiles of long-term manured soil.

Animal manure fertilization facilitates the proliferation and dissemination of antibiotic resistance genes (ARGs) in soil, posing high risks to humans and ecosystem health. Although studies suggest that soil types could shape the ARG profiles in greenhouse soil, there is still a lack of comparative studies on the fate of ARGs in different types of manured soils under field trials. Thus, a metagenomic approach was used to decipher the fate of ARGs in 12-year long-term fertilized (inorganic fertilizer, compost manure and a mix of them) acidic, near-neutral and alkaline soils. A total of 408 unique ARG subtypes with multidrug, glycopeptide, beta-lactam and aminoglycoside resistance genes were identified as the most universal ARG types in all soil samples. Genes conferred to beta-lactam was the predominant ARG type in all the manure-amended soils. Genomic and statistical analyses showed that manure application caused the enrichment of 98 and 91 ARG subtypes in acidic and near-neutral soils, respectively, and 8 ARG subtypes in alkaline soil. The abundances of Proteobacteria (acidic and near-neutral soils) and Actinobacteria (alkaline soil), which are the potential hosts of ARGs, were clearly increased in manured soils. Random forest modelling and Pearson correlation analysis revealed that the soil properties (pH and bio-available Zn) and mobile genetic elements had considerable impacts on the transmission of ARGs. A structural equation model further indicated that soil types shaped the ARG profiles by significantly (P < 0.01) influencing the soil properties, bacterial abundance and bacterial diversity, where bacterial abundance was the major factor influencing the ARG profiles. This study systematically explored the mechanisms shaping the ARG profiles of long-term manured soils, and this information could support strategies to manage the dissemination of ARGs in different soil types.

Astaxanthin from Haematococcus pluvialis ameliorates the chemotherapeutic drug (doxorubicin) induced liver injury through the Keap1/Nrf2/HO-1 pathway in mice.

The aim of this study is to probe a new function of astaxanthin (AST) from Haematococcus pluvialis on chemotherapeutic drug induced liver injury in mice. Doxorubicin-induced liver injury was treated with different doses of AST, and the body weight, food intake, urinalysis, liver function, and oxidative stress indexes were examined. The hepatocyte apoptosis level, pathological sections of liver tissue and the expression of antioxidant related genes were also determined. This study found that DOX could induce serious liver injury through cytotoxicity. AST treatment could decrease the level of liver function indexes (ALT, GOT, ALP and TBil), reduce the concentration of MDA and ROS, and increase the activities of SOD, CAT and GPX in the liver. AST could also repair the damaged hepatocyte in mice with liver injury and reduce the degree of the cellular apoptosis. In addition, AST could interfere with the expression of some related genes in the Keap1/Nrf2 signaling pathway by downregulating the expression of Keap1 and activating the transcription factor Nrf2 via enhancing the level of ERK, which upregulates downstream peroxiredoxins. The present research found and illustrated a new food function of AST, indicating that AST could be used in the therapy of chemotherapy induced side effects.

Polysaccharide from Spirulina platensis ameliorates diphenoxylate-induced constipation symptoms in mice.

The aim of this study is to probe new functions of a polysaccharide from Spirulina platensis (PSP) on constipation and intestinal microbiota in mice. Diphenoxylate-induced constipation in mice was treated with different doses of PSP, followed by examining the defecation patterns, levels of acetyl cholinesterase (AchE), nitric oxide (NO), and tissue section histopathology. The composition of intestinal microbiota was determined by genome sequencing analysis of the 16S rDNA. This study found that the average molecular weight of PSP was 29, 600 Da, and mainly monosaccharides of PSP were rhamnose (24.7%), glucose (16.15%) and galactose (13.32%). The beneficial effects of PSP treatment include defecation improvement, increase of AchE activity, reduction of NO concentration, renovation of the damaged intestinal villus and affection on the expression of some related genes in the constipated mice. In addition, PSP had significant effects on the gut microbiota, showing the enhancement in abundance of beneficial bacteria including Akkermansia, Lactobacillus, Butyricimonas, Candidatus Arthromitus and Prevotella, and the reduction in abundance of harmful bacteria such as Clostridium and Dorea. The present s uncovered a new function of PSP, indicating that PSP could be used in constipation therapies.

Effects of different fertilizers on residues of oxytetracycline and microbial activity in soil.

Oxytetracycline (OTC), a type of tetracycline, was used widely as feeding additive to promote animal growth in breeding industry in the world. Its residue has been found in soils. Based on potted maize experiments, the influences of OTC on soil enzyme activity, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and soil fertility were investigated during the growth stages of maize receiving different fertilizers (spent mushroom substrate, worm manure, and biochar, among others, with single applications and combined applications with their cooperating microbial inoculants). The results showed that OTC negatively affected the soil enzyme activity, MBC, MBN, and cation exchange capacity (CEC). Enzyme activity, MBC, and MBN were more sensitive to OTC than soil fertility. The significant negative correlations were found between OTC concentrations and catalase, MBC, and CEC (p < 0.05). This indicated that the effects of OTC on soil can be alleviated by different fertilizers, and the effects of T6 (microbial inoculants), T7 (microbial inoculants + worm manure), T8 (microbial inoculants + SMS), and T9 (microbial inoculants + biochar) were the best among those of all treatments. During the mature stage of maize, the content of OTC in the soil of T7 was the lowest compared with other treatments. The results provide a good basis for the development of methods to remediate OTC-contaminated soils.