miR-460b-5p promotes proliferation and differentiation of chicken myoblasts and targets RBM19 gene.

The meat production of broilers is crucial to economic benefits of broiler industries, while the slaughter performance of broilers is directly determined by skeletal muscle development. Hence, the broiler breeding for growth traits shows a great importance. As a kind of small noncoding RNA, microRNA (miRNA) can regulate the expression of multiple genes and perform a wide range of regulation in organisms. Currently, more and more studies have confirmed that miRNAs are closely associated with skeletal muscle development of chickens. Based on our previous miR-seq analysis (accession number: PRJNA668199), miR-460b-5p was screened as one of the key miRNAs probably involved in the growth regulation of chickens. However, the regulatory effect of miR-460b-5p on the development of chicken skeletal muscles is still unclear. Therefore, miR-460b-5p was further used for functional validation at the cellular level in this study. The expression pattern of miR-460b-5p was investigated in proliferation and differentiation stages of chicken primary myoblasts. It was showed that the expression level of miR-460b-5p gradually decreased from the proliferation stage (GM 50%) to the lowest at 24 h of differentiation. As differentiation proceeded, miR-460b-5p expression increased significantly, reaching the highest and stabilizing at 72 h and 96 h of differentiation. Through mRNA quantitative analysis of proliferation marker genes, CCK-8 and Edu assays, miR-460b-5p was found to significantly facilitate the transition of myoblasts from G1 to S phase and promote chicken myoblast proliferation. mRNA and protein quantitative analysis of differentiation marker genes, as well as the indirect immunofluorescence results of myotubes, revealed that miR-460b-5p significantly stimulated myotube development and promote chicken myoblast differentiation. In addition, the target relationship was validated for miR-460b-5p according to the dual-luciferase reporter assay and mRNA quantitative analysis, which indicates that miR-460b-5p was able to regulate RBM19 expression by specifically binding to the 3' UTR of RBM19. In summary, miR-460b-5p has positive regulatory effects on the proliferation and differentiation of chicken myoblasts, and RBM19 is a target gene of miR-460b-5p.

[Effects of Different Concentrations of Lanthanum on the Growth and Uptake of Pb by Maize Grown Under Moderate Lead Stress].

A greenhouse pot experiment was conducted to investigate the effects of different concentrations of lanthanum (0 mg·kg-1, 50 mg·kg-1, 200 mg·kg-1 and 800 mg·kg-1) on growth, nutrient uptake, C:N:P stoichiometry, and La and Pb uptake by maize (Zea mays L.) under moderate lead stress (200 mg·kg-1) and evaluate the interaction of rare earth elements and heavy metals in the soil-plant system. The aim was to provide basic data and a theoretical basis for the remediation of rare earth element and heavy metal-co-contaminated soils in a rare earths mining area. The results indicate that the concentrations of CH3COONH4-EDTA-extractable La and Pb significantly increase and decrease, respectively, with increasing La concentrations of the soils. The shoot dry weights of maize significantly decreases by 17.90% to 81.17% and the root to shoot ratio of maize significantly increases by 21.74% to 86.96% with increasing La concentrations of the soils. With increasing La concentrations in soils, the root P contents of maize significantly decrease by 19.16% to 89.68%. The shoot P and N contents significantly decrease by 65.51% to 91.98% and 48.27% to 76.58%, respectively, when the exogenous application of La is 200 mg·kg-1 and 800 mg·kg-1, respectively. The increasing La concentrations in soils significantly increase the C:P and N:P ratios and shoot and root La concentrations of maize. The shoot and root Pb concentrations of maize significantly increase by 52.61% to 99.01% and 15.99% to 44.34%, respectively, with increasing La concentrations. Overall, the increasing La concentrations in soils significantly decrease the K, Ca, and Mg contents of maize. The results demonstrate that the presence of rare earth elements aggravates the phytotoxicity of heavy metals to plant and ecological risks. Further research should focus on the effects and mechanisms of rare earth elements on the heavy metal uptake by plants.

Effects of arbuscular mycorrhizal symbiosis on growth, nutrient and metal uptake by maize seedlings (Zea mays L.) grown in soils spiked with Lanthanum and Cadmium.

Multiple contaminants can affect plant-microbial remediation processes because of their interactive effects on environmental behaviour, bioavailability and plant growth. Recent studies have suggested that arbuscular mycorrhizal fungi (AMF) can facilitate the revegetation of soils co-contaminated with rare earth elements (REEs) and heavy metals. However, little is known regarding the role of AMF in the interaction of REEs and heavy metals. A pot experiment was conducted to evaluate the effects of Claroideoglomus etunicatum on the biomass, nutrient uptake, metal uptake and translocation of maize grown in soils spiked with Lanthanum (La) and Cadmium (Cd). The results indicated that individual and combined applications of La (100 mg kg-1) and Cd (5 mg kg-1) significantly decreased root colonization rates by 22.0%-35.0%. With AMF inoculation, dual-metal treatment significantly increased maize biomass by 26.2% compared to single-metal treatment. Dual-metal treatment significantly increased N, P and K uptake by 20.1%-76.8% compared to single-metal treatment. Dual-metal treatment significantly decreased shoot La concentration by 52.9% compared to single La treatment, whereas AM symbiosis caused a greater decrease of 87.8%. Dual-metal treatment significantly increased shoot and root Cd concentrations by 65.5% and 58.7% compared to single Cd treatment and the La translocation rate by 142.0% compared to single La treatment, whereas no difference was observed between their corresponding treatments with AMF inoculation. Furthermore, AMF had differential effects on the interaction of La and Cd on metal uptake and translocation under the background concentrations of soil metals. Taken together, these results indicated that AMF significantly affected the interaction between La and Cd, depending on metal types and concentrations in soils. These findings promote a further understanding of the contributions of AMF to the phytoremediation of co-contaminated soil.

[Effects of Arbuscular Mycorrhizal Fungi on the Growth and Uptake of La and Pb by Maize Grown in La and Pb-Contaminated Soil].

A greenhouse pot experiment was conducted to investigate the effects of arbuscular mycorrhizal (AM) fungi Claroideoglomus etunicatum (CE) and Rhizophagus intraradices (RI) on AM colonization rate, biomass, nutrient uptake, C:N:P stoichiometry, and the uptake and transport of lanthanum (La) and lead (Pb) by maize (Zea mays L.) grown in La-and Pb-contaminated soils (combined La-Pb concentrations of 50, 200, and 800 mg·kg-1). The aim was to provide a scientific basis for the remediation of soils contaminated by rare earth elements and heavy metals. The results indicated that symbiotic associations were successfully established between the two isolates and maize, and the average AM colonization rate ranged from 26.7% to 95.8%. The increasing concentrations of La and Pb in soils significantly decreased the mycorrhizal colonization rate, biomass, and mineral nutrition concentrations of the maize, and significantly increased C:P and N:P ratios and the concentrations of La and Pb in shoots and roots of maize. The shoot and root dry weights of maize were significantly increased by 17.8%-158.9% with two AM fungi inoculations, while the P concentration of shoots and roots of the maize were significantly increased by 24.5%-153.8%. Inoculation with two AM fungi decreased the C:P and N:P ratios, consistent with the growth rate hypothesis. With AM fungi inoculation in three types of La-Pb co-contaminated soils, root Pb concentrations of the maize significantly increased by 51.3%-67.7%; shoot Pb concentrations of the maize significantly decreased by 16.0%-67.7%; and the transport rate of Pb from root to shoot of the maize decreased by 31.5%-54.7%. Meanwhile, inoculation with AM fungi significantly increased the shoot La concentrations in the maize grown in soils mildly contaminated with La-Pb, while it significantly decreased shoot La concentrations, increased root La concentrations of maize, and inhibited the transport of La from root to shoot of the maize grown in soils moderately contaminated with La-Pb, but had no significant effect in severely contaminated soils. The results showed that AM fungi had the potential to promote phytoremediation of soils contaminated with rare earth elements and heavy metals, with potential applications to revegetate such contaminated soil ecosystems.