毛白杨人工幼林施用N、P、K效果的研究

本文研究沙地营造毛白杨人工幼林施肥的效果.结果表明:在该土壤条件下,最佳施肥总量450kg/ha,材积生长量比对照提高32.1%;最佳配比N∶P_2O_5∶K_2O=4∶3∶0.5;最佳施肥量与最佳配比二者组合的林木生长更快,材积比对照提高一倍.施肥增加了毛白杨叶子中叶绿素和N、P、K的含量,同时叶重、叶面积等也有所增加,因而促进了毛白杨生长.     

不同施氮量与氮磷钾配比对烤烟农艺性状和产质影响的研究

该研究探索出了信阳地区烤烟的最佳施氮量以及不同施氮水平下的N、P、K最优配比.     

N、K配施对燕麦生长特性和鲜草产量影响的研究

以白燕7号燕麦为材料,研究了不同配比的N肥和K肥对燕麦生长特性(有效分蘖、茎粗、叶面积、穗长)和鲜草产量的影响.结果表明:施N和施K对有效分蘖、茎粗、叶面积、穗长都有显著的影响(P<0.05),随着施肥量的增加呈先增后降的变化趋势;鲜草产量在不同生育时期随着施N量的增加而增加,随着施K量的增加呈先增后降的变化,其中N100K105的增产效应在施肥处理组合中最佳.     

不同退化高寒草甸矮嵩草和高山嵩草无性系繁殖规律

对不同退化高寒草甸矮嵩草和高山嵩草的繁殖对策进行了初步研究.结果表明,不同退化程度下两种嵩草都以营养繁殖为主扩大无性系繁殖后代,其中两种嵩草的芽分别占无性系小株数的比例最大;有性繁殖能力较弱.芽向一龄分蘖的转化率较高,各退化程度下矮嵩草平均分株内芽转化率达76%,高山嵩草达91%.两种嵩草无性系的扩大主要由二龄分蘖产生大量的营养芽来实现,芽通过一龄分蘖、二龄分蘖到生殖枝的转化率最低,其中矮嵩草无性系最多只有14%,高山嵩草最多只有5.7%.矮嵩草无性系分株生物量中根茎>叶>根,高山嵩草根茎>根>叶,地下生物量>地上生物量.     

Potassium fertilization of rainfed olive orchards

Experiments under both greenhouse and field conditions were performed to study the influence of the type of salt applied (KCl or K₂SO₄) and to compare the effectiveness of their method of application (soil versus foliar) on leaf K concentration and yield in olive trees established under rainfed conditions. In the experiment performed in the greenhouse, mist-rooted 3-month-old ‘Picual’ olive plants growing in 2-l pots containing perlite were irrigated with a complete nutrient solution containing either 0.05 or 2.5 mM KCl during 128 days after transplanting (DAT). A group of plants received one K soil application at a dose equivalent to 1 kg of K per tree at 63 DAT. Another group received four foliar applications at 63, 78, 93 and 108 DAT with a K concentration of 10.5 g/l. The experiment under field conditions was developed with 80-year-old ‘Hojiblanca’ olive trees. Soil application was performed in March every year at a rate of 1 kg K/tree by injecting K fertilizer around the trees. Foliar sprays were carried out in April, March, June and July every year with the same K concentration used for the greenhouse experiment. The results showed that, under both field and greenhouse conditions, either KCl or K₂SO₄ increased K concentration in leaves. Also, both K salts had a positive effect in increasing K content in fruits under field conditions, although the intensity of the increase varied among years. Tree water stress and low K status seemed to influence K uptake. The method of K application, soil or foliar, did not affect the effectiveness of K fertilization.     

Refeeding and insulin activate the AKT/p70S6 kinase pathway without affecting IRS1 tyrosine phosphorylation in chicken muscle

p70 S6 kinase (p70S6K) is a key enzyme involved in the control of protein synthesis. We have previously shown that this kinase is insulin sensitive in chicken muscle despite a relative insulin resistance in the early steps of insulin receptor signaling in this tissue, particularly with no change in tyrosine phosphorylation of the insulin receptor substrate 1 (IRS1). The aim of the present study is to further study the p70S6K pathway in chicken muscle. By analyzing in silico several kinases involved in the protein kinase B (PKB also called AKT)/target of rapamycin (TOR)/p70S6K pathway in the chicken, we showed that the amino acid sequence of the proteins exhibited a very high identity with their homologs in mammalian species and Drosophila. We investigated the regulation of these kinases in vivo or in vitro. Refeeding and insulin treatment significantly (P<0.05) increased the phosphorylation and/or activity of kinases upstream of p70S6K such as AKT and TOR. Similarly, refeeding and insulin increased the phosphorylation of p70S6K on key residues (i.e. T389, T229 and T421/S424) and the phosphorylation of a p70S6K downstream target, the ribosomal protein S6 (by 3-10-fold, P<0.05). Interestingly, we also showed an increase in the phosphorylation level of IRS1 on S632/S635, sites involved in insulin resistance. In conclusion, the AKT/TOR/p70S6K pathway is activated by refeeding and insulin injection, which might negatively regulate IRS1 tyrosine phosphorylation. These results indicate some particularities of the insulin signaling in chicken muscle and suggest the involvement of p70S6K in these features.     

Effects of PI3K/AKT signaling pathway on polarization of M2 macrophages induced by SjCystatin

AIM: To investigate the subtype of M2 macrophages induced by Schistosoma japonicum cystatin (SjCystatin) and to determine the mechanism underlying these effects.METHODS: The releases of IL-10 and IL-12, and the expression of macrophage subtype markers LIGHT (M2b) and Arg-1 (M2a+M2c) were assessed by ELISA, RT-qPCR and Western blot. The phosphorylation level of AKT was assessed by Western blot.RESULTS: SjCystatin promoted the continuous increase in IL-10 level at 6 h, 12 h and 24 h, and increased the amount of mRNA and protein expression of LIGHT, but down-regulated the amount of mRNA and protein expression of AKT. The addition of PI3K/AKT inhibitor reduced the release of IL-10 at 12 h and 24 h, reduced the mRNA and protein expression of LIGHT at 24 h, up-regulated the mRNA and protein expression of Arg-1 at 24 h, and decreased the phosphorylation level of AKT.CONCLUSION: SjCystatin promotes the differentiation of M2 macrophage to M2b macrophage subtype, and the PI3K/AKT signaling pathway is involved in this process.     

NVP-BEZ235 induces autophagy of polycystic kidney rat cholangiocytes

AIM: To explore the effect of dual PI3K/Akt/mTOR inhibitor NVP-BEZ235 on autophagy of polycystic kidney (PCK) rat cholangiocytes. METHODS: The protein levels of p-mTOR and p-Akt in the bile duct epithelial cells were examined by immunohistochemistry. The effect of NVP-BEZ235 on the viability of cholangiocytes was detected by WST-1 assay. The levels of PI3K/Akt/mTOR signaling pathway and autophagy-related proteins with NVP-BEZ235 treatment were determined by Western blot. The effects of LC3 and Beclin 1 silencing, and authophagy-specific inhibitor 3-methyladenine (3-MA) on the cell viability were analyzed by WST-1 assay. RESULTS: The protein levels of p-Akt and p-mTOR were highly increased in the bile duct epithelium of the PCK rats. NVP-BEZ235 significantly inhibited the viability of the cholangiocytes in a dose- and time-dependent manner (P<0.05). NVP-BEZ235 significantly reduced the levels of PI3K/Akt/mTOR signaling pathway-related proteins in the PCK rat cholangiocytes. NVP-BEZ235 upregulated the autophagy-specific proteins LC3 II and Beclin 1. The inhibitory effect of NVP-BEZ235 on the cell viability was weakened by treatment with 3-MA and knockdown of LC3 and Beclin 1 (P<0.01).CONCLUSION: The PI3K/Akt/mTOR inhibitor NVP-BEZ235 suppresses the viability of PCK rat cholangiocytes, and the mechanism is closely related with autophagy.     

高等植物K+吸收及转运的分子机制研究进展

K⁺是植物生长必需的营养元素。K⁺被植物根系吸收后,有效地向地上部转运,在跨膜转运的过程中主要由次级K⁺转运蛋白和K⁺通道介导。KT/HAK/KUP和HKT家族是参与植物体内K⁺吸收及转运的两类主要K⁺转运蛋白,其中HKT家族参与K⁺转运的成员仅存在于单子叶植物中,它们在植物生长发育、渗透调节等过程中均发挥重要作用。Shaker家族是K⁺通道中最早发现且研究最为深入的一类电压门控型通道,是植物K⁺吸收的重要途径之一。本研究从结构特征、定位和组织表达、功能调控等方面对植物KT/HAK/KUP家族、HKT家族和Shaker通道进行综述,最后对未来的主要研究方向做了展望。     

乳酸菌发酵饲料对SPF鸡免疫功能的影响

本试验旨在研究乳酸菌发酵饲料对SPF鸡免疫功能和磷脂酰肌醇三激酶/蛋白激酶B(PI3K/Akt)信号通路的影响。选取14日龄无特定病原体(SPF)雏鸡120羽,随机分为4组,每组5个重复,每个重复6羽。对照组饲喂基础饲料,发酵饲料组饲喂乳酸菌发酵饲料,基础阻断剂组为基础饲料加PI3K阻断剂组,乳酸菌阻断剂组为乳酸菌发酵饲料加PI3K阻断剂。试验期21 d。结果表明:发酵饲料组与对照组、乳酸菌阻断剂组与基础阻断剂组比较,乳酸菌发酵饲料可降低雏鸡耗料增重比(P<0.05),提高日增重、T淋巴细胞转化率、B淋巴细胞转化率、白细胞介素-2(IL-2)、白细胞介素-6(IL-6)、干扰素-α(IFN-α)、免疫球蛋白M(IgM)、免疫球蛋白A(IgA)和免疫球蛋白G(IgG)含量(P<0.05),提高雏鸡新城疫抗体(NDV-Ab)水平(P<0.05),提高雏鸡脾脏中PI3K、Akt mRNA和蛋白表达量(P<0.05);基础阻断剂组与对照组、乳酸菌阻断剂组与发酵饲料组比较,PI3K阻断剂可以提高雏鸡耗料增重比(P<0.05),降低日增重、T淋巴细胞转化率、B淋巴细胞转化率、IL-2、IL-6、IFN-α、IgM、IgA和IgG含量(P<0.05),降低雏鸡NDV-Ab水平(P<0.05),降低雏鸡脾脏中PI3K、Akt mRNA和蛋白表达量(P<0.05)。由此可见,乳酸菌发酵饲料可能是通过激活PI3K/Akt信号通路来提高SPF雏鸡的免疫功能。