Structural and metabolic responses of Ceratophyllum demersum to eutrophic conditions

Eutrophication in water bodies affects the growth of aquatic plants. In this study, we conducted static experiments to better understand the structural and metabolic responses of Ceratophyllum demersum under eutrophication conditions. The anatomical structure, nitrogen (N) and phosphorous (P) levels in tissue, malondiadehyde (MDA), and activities of three antioxidases (peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT)) of C. dermersum cultured at different nutrient levels (oligotropher, mesotropher, eutropher, and hypertrophics) were investigated. The results showed that with nutrient concentration increase, disordered anatomical structures and a cavity in stem of C. demersum existed; there was also an increase in the N and P contents of C. demersum. The MDA content improved with nutrient increase while POD and SOD activities initially increased and later decreased. CAT activity also increased during the experimental period. These finding suggested that changes in stem anatomical structure and the increase in antioxidant enzyme activity can be served as the indicators of the response of C. demersum to eutrophication conditions.Keywords: Submerged aquatic plants, anatomical structure, antioxidant enzymes, nitrogen and phosphorus eutrophicationAfrican Journal of Biotechnology Vol. 9(35), pp. 5722-5729, 30 August, 201

Combined effect of molybdenum and nitrogen fertilization on nitrogen metabolism and amino acid content in tobacco leaves

IntroductionThis study investigated the combined effects of molybdenum (Mo) and nitrogen (N) fertilization on N metabolism and amino acid content in the leaves of flue-cured tobacco (Nicotiana tabacum L.) during its mature stage through a pot experiment.MethodsDifferent application levels of Mo (0, 0.15, 0.30 mg/kg soil) and N (0.06, 0.24, 0.42 g/kg soil) were set to observe and analyze changes in leaf quality, N, and amino acid content in the tobacco plants.ResultsThe results revealed that the N fertilizer application level exhibited a primary effect on regulating the total nitrogen, nitrate nitrogen, soluble protein, and amino acid nitrogen concentrations within tobacco leaves, while the effectiveness of Mo fertilization was influenced by the level of N applied. Specifically, under the conditions of 0.24 g/kg soil N and 0.30 mg/kg soil Mo application, the N content, N accumulation, and dry matter mass of the tobacco plants increased significantly by 110%, 204%, and 48%, respectively. Concurrently, nitrate reductase activity increased by 107-fold, and the nitrate nitrogen content was relatively low, contributing to enhanced tobacco yield and safety. Moreover, this treatment led to a notable (170%) increase in free amino acid nitrogen content, with minimal impact on total amino acids and soluble proteins. Notably, it effectively increased the content of free amino acids beneficial to the sensory quality of tobacco (such as histidine, arginine, aspartic acid, isoleucine, and glutamic acid) without reducing the total amino acid content, while simultaneously reducing other amino acids that might affect quality. Therefore, the combined application of 0.30 mg/kg soil Mo and 0.24 g/kg soil N specifically optimized the amino acid composition in tobacco leaves, positively impacting overall quality and market competitiveness.DiscussionThis study provides a theoretical basis for the rational application of Mo fertilizer in Mo-deficient areas to improve the yield and quality of flue-cured tobacco

Cisplatin inhibits the proliferation of Saos-2 osteosarcoma cells via the miR-376c/TGFA pathway

The transforming growth factor alpha (TGFA) gene is involved in the proliferation and metastasis of various tumors, but its role in cell sensitivity to cisplatin chemotherapy is unclear. In this study, we investigated the mechanism underlying inhibitory effects of cisplatin on growth and proliferation of osteosarcoma cells. Osteosarcoma and normal skeletal muscle tissues were collected from 26 patients by biopsy. TGFA was silenced or overexpressed in Saos-2 osteosarcoma cells by transfection with TGFA-shRNA or TGFA ORF clone, respectively. MiR-376c was inhibited or overexpressed by transfection of Saos-2 cells with miR-376c sponge or miR-376c mimics, respectively. Cell growth was analyzed by MTT assay and cell proliferation by BrdU assay. MiR-376c and TGFA mRNA expression was detected by quantitative reverse transcription PCR and TGFA protein expression by Western blot. The target relationship between miR-376c and TGFA was assessed by luciferase reporter assay. Both in osteosarcoma tissues and Saos-2 cells, miR-376c expression was significantly decreased and TGFA mRNA expression was significantly increased compared with control. Transfection of Saos-2 cells with TGFA-shRNA silenced TGFA expression and significantly inhibited cell growth and proliferation. TGFA mRNA and protein expression in Saos-2 cells significantly decreased with increasing cisplatin concentrations (2.5–10 mg/L). Transfection with TGFA ORF clone reversed the inhibitory effects of cisplatin on Saos-2 cell proliferation. Compared with cisplatin (10 mg/L) treatment alone, the combined treatment with cisplatin and miR-376c mimics inhibited the proliferation of Saos-2 cells more significantly. MiR-376c suppressed TGFA expression by directly interacting with its 3' UTR region. Overall, cisplatin inhibited the proliferation of Saos-2 cells by upregulating miR-376c and downregulating TGFA expression

Earthworms and rice straw enhanced soil bacterial diversity and promoted the degradation of phenanthrene

Abstract Background Since the industrial revolution, the contamination of agricultural soils by polycyclic aromatic hydrocarbons (PAHs) has increasingly become of serious global environmental concern and poses a huge threat to human beings and natural ecosystems. Microbial degradation is a proved technology mostly used to depollute polycyclic aromatic hydrocarbon (PAH) in the environment. However, very limited information is available regarding the interaction of earthworms with rice straw on the soil microbial community and the degradation of phenanthrene. This study was performed to enlighten the rice straw and earthworms’ interaction on soil bacterial abundance and structure and phenanthrene removal. Results Result about functional gene information revealed that both rice straw and earthworm enhanced phenanthrene degradation. Subsequently, both Shannon diversity index (r2 = − 0.8807, p &lt; 0.001) and bacterial 16S rRNA genes (r2 = − 0.7795, p &lt; 0.001) negatively correlated with the remaining phenanthrene concentration in soil. The application of both rice straw and earthworms in soil had the lowest ratio of soil remaining phenanthrene concentration (0.16 ± 0.02), the highest Shannon diversity index (6.45 ± 0.2) and the highest bacterial 16S rRNA genes. This implied that both earthworms and rice straw might improve the phenanthrene metabolism by increasing soil bacteria diversity. The abundance of genera Pseudomonas, Luteimonas, Rhodanobacter, Sphingomonas, Gemmatimonas, Flavobacterium, and Leifsonia was significantly increased in the presence of both earthworms and rice straw and was found to negatively correlate with the remaining phenanthrene concentration in soil. Conclusion Based on these results, this study offers clear and strong evidences that the positive interaction between earthworms and rice straw could promote phenanthrene degradation in soil. These finding will improve our understanding on the importance of the natural resources forsaken and how they can interact with the soil macro- and microorganisms to change soil structure and enhance PAH degradation in soil. </jats:sec

Land Inequality and Its Influencing Factors in Rural China in Modern Times: A Systematic Review

Land inequality is a global and historic issue. There is a problem of unequal distribution of land ownership in modern China; research results on this topic are extensive, but the conclusions are quite different or even completely opposite. This study systematically reviewed the research results obtained for land inequality in modern China and performed an international comparison. The results show that the debate on the estimation of land inequality in modern China has existed for a long time. The overall estimation of land inequality has been repeatedly revised, and many subdivision estimates show great regional variability. The application of the Gini coefficient and other methods can address the drawbacks of traditional methods. A change trend toward equality was found to be more likely in the late modern period. The majority of studies support the notion that debt burden, power, and strength exacerbated land inequality in modern China, whereas the inheritance system with equal sharing, revolution, and reform reduced the land inequality. However, the impact of disasters and commercialization remains controversial. Compared with relevant international studies, the study on land inequality in modern China focused on estimations with unique interpretation perspectives, but there are limitations in terms of the research methods used.</jats:p

Nitric Oxide Mediates Molybdenum-Induced Antioxidant Defense in Wheat under Drought Stress

Molybdenum (Mo) has been reported to alleviate drought stress by enhancing antioxidant defense in plants, but the underlying mechanism remains unclear. Here, we hypothesized that Mo mediates nitric oxide (NO)-induced antioxidant defense through Mo-enzymes, particularly by nitrate reductase (NR) in wheat under drought stress. The 30-day-old wheat seedlings cultivated in -Mo (0 μM Mo) and +Mo (1 μM Mo) Hoagland solutions were detached and then pretreated with Mo-enzyme inhibitors, NO scavengers, NO donors or their combinations according to demands of complementary experiment under 10% polyethylene glycol 6000 (PEG)-stimulated drought stress (PSD). Mo supplementation increased the activities and transcripts of antioxidant enzymes, decreased H2O2 and MDA contents, and elevated NO production, implying that Mo-induced antioxidant defense may be related to NO signal. Complementary experiment showed that NO production was induced by Mo, while suppressed by Mo-enzyme inhibitors and NO scavengers, but restored by NO donors, suggesting that Mo-induced increase of NO production may be due to the regulation by Mo-enzymes. Further experiment indicated that the increased activities and transcripts of antioxidant enzymes induced by Mo were suppressed by Mo-enzyme inhibitors and NO scavengers, and NO donors could eliminate their suppressing effects. Moreover, Mo application increased NR activity and inhibitors of Mo-enzymes inhibited NR activity in wheat leaves under PSD, suggesting that NR might involve in the regulation of Mo-induced NO production. These results clearly indicate that NO mediates Mo-induced antioxidant defense at least partially through the regulation of NR

Land Inequality and Its Influencing Factors in Rural China in Modern Times: A Systematic Review

Land inequality is a global and historic issue. There is a problem of unequal distribution of land ownership in modern China; research results on this topic are extensive, but the conclusions are quite different or even completely opposite. This study systematically reviewed the research results obtained for land inequality in modern China and performed an international comparison. The results show that the debate on the estimation of land inequality in modern China has existed for a long time. The overall estimation of land inequality has been repeatedly revised, and many subdivision estimates show great regional variability. The application of the Gini coefficient and other methods can address the drawbacks of traditional methods. A change trend toward equality was found to be more likely in the late modern period. The majority of studies support the notion that debt burden, power, and strength exacerbated land inequality in modern China, whereas the inheritance system with equal sharing, revolution, and reform reduced the land inequality. However, the impact of disasters and commercialization remains controversial. Compared with relevant international studies, the study on land inequality in modern China focused on estimations with unique interpretation perspectives, but there are limitations in terms of the research methods used