不同光温条件对翠碧一号烤烟碳氮代谢的影响

为探究烤烟生长后期对光温交互胁迫的响应规律,尤其是应对高温强光等逆境条件时烤烟碳氮的代谢变化,以翠碧一号为供试品种,分别设置25.0℃遮光、25.0℃强光、35.0℃遮光和35.0℃强光等4种不同光温条件处理以探究其对烟株碳氮代谢的影响(光照强度均为1600μmol/m2·s).结果表明:高温强光处理下,烟株叶片光合色...     

Effect of low-nitrogen stress on photosynthesis and chlorophyll fluorescence characteristics of maize cultivars with different low-nitrogen tolerances

Nitrogen(N) is a critical element for plant growth and productivity that influences photosynthesis and chlorophyll fluorescence. We investigated the effect of low-N stress on leaf photosynthesis and chlorophyll fluorescence characteristics of maize cultivars with difference in tolerance to low N levels. The low-N tolerant cultivar ZH311 and low-N sensitive cultivar XY508 were used as the test materials. A field experiment(with three N levels: N0, 0 kg ha–1; N1, 150 kg ha–1; N2, 300 kg ha–1) in Jiyanyang, Sichuan Province, China, and a hydroponic experiment(with two N levels: CK, 4 mmol L–1; LN, 0.04 mmol L–1) in Chengdu, Sichuan Province, China were conducted. Low-N stress significantly decreased chlorophyll content and rapid light response curves of the maximum fluorescence under light(Fm′), fluorescence instable state(Fs), non-photochemical quenching(qN), the maximum efficiency of PSII photochemistry under dark-adaption(Fv/Fm), potential activity of PSII(Fv/Fo), and actual photochemical efficiency of PSII(ΦPSII) of leaves. Further, it increased the chlorophyll(Chl) a/Chl b values and so on. The light compensation point of ZH311 decreased, while that of XY508 increased. The degree of variation of these indices in low-N tolerant cultivars was lower than that in low-N sensitive cultivars, especially at the seedling stage. Maize could increase Chl a/Chl b, apparent quantum yield and light saturation point to adapt to N stress. Compared to low-N sensitive cultivars, low-N tolerant cultivars maintained a higher net photosynthetic rate and electron transport rate to maintain stronger PSII activity, which further promoted the ability to harvest and transfer light. This might be a photosynthetic mechanism by which low-N tolerant cultivar adapt to low-N stress.     

Effects of Supplementing Holstein Heifers with Dietary Melatonin during Late Gestation on Growth and Cardiovascular Measurements of their Offspring

The objective was to examine the effects of supplementing dams with dietary melatonin during late gestation on offspring growth and cardiovascular measurements. On day 190 of gestation, heifers (n = 20) were blocked by body weight and randomly assigned to one of two dietary treatments consisting of 20 mg of dietary melatonin per day [melatonin (MEL)] or no melatonin supplementation [control (CON)]. Dietary treatments were terminated on day 262 of gestation. At birth, calves were separated from their dams with no further treatments. Calf (n = 18) blood pressure, cortisol, nitrites and total antioxidant capacity were collected on weeks 0, 1, 2, 3 and 4 of age. Calf hepatic portal blood flow and concentrations of insulin‐like growth factor 1 were determined on weeks 0 and 4 of age. Calf body weight, abdominal girth, hip height and wither height increased (p < 0.05) with age. An age by treatment interaction (p < 0.01) was observed for calf body weight, which was increased at weeks 8 and 9 of age in calves born to MEL heifers compared to calves born to CON heifers. Pulse pressure, mean arterial pressure, absolute hepatic portal blood flow and blood flow relative to calf body weight were not different (p > 0.05) between treatments. A main effect of calf age (p < 0.05) was observed for concentrations of insulin‐like growth factor 1, which was decreased at week 4 compared to week 0. An age by treatment interaction (p < 0.05) was observed for cortisol, which was decreased at week 2 in calves from MEL‐treated dams compared to calves from CON‐treated dams. Early post‐natal growth was altered in offspring born to dams supplemented with dietary melatonin. This could lead to further foetal programming implications in conjunction with post‐natal development.     

不同抗性甘薯品种感染疮痂病后的细胞超微结构

在甘薯疮痂病胁迫下,抗病性不同的甘薯品种金山1255(感病)和广薯8870(抗病)染病后,叶片细胞的超微结构都发生了变化,最敏感的部位均是细胞膜;活性氧产生的两个主要部位(叶绿体和线粒体)也受到了不同程度的攻击;感病品种的叶绿体和线粒体外膜外突成致密的小球,产生了大量的吞噬体,抗病品种则产生了大量用于修复细胞膜的高尔基小泡.     

表达绿色荧光蛋白重组单核细胞增多性李斯特菌的构建

将编码绿色荧光蛋白(GFP)的基因融合到单核细胞增多性李斯特菌actA基因启动子和信号肽下游,应用同源重组技术构建了含gfp的重组李斯特菌突变株.PCR扩增及其产物的酶切鉴定均证实目的基因gfp融合到李斯特菌基因组中.荧光显微镜下可见重组菌体发绿色荧光.SDS-PAGE电泳和免疫印迹结果显示重组李斯特菌表达的GFP分子量约为28 kD,与预计的分子量大小一致.重组菌对鸡胚和小鼠的毒力以及对体外培养细胞的侵袭力均低于野生型李斯特菌.该重组菌可用于研究李斯特菌的致病机理和食品加工过程中微生物污染控制的指示性细菌.     

栽培基质添加豆粕对白背毛木耳产量及品质的影响

【目的】探讨在栽培基质中添加豆粕对白背毛木耳产量和质量的影响,为白背毛木耳高产栽培提供参考依据。【方法】在白背毛木耳传统培养料中添加1.0%、3.0%及5.0%豆粕,以不添加豆粕为对照(CK),观察、测定不同培养料配方的白背毛木耳菌丝生长情况、产量及效益,分析不同处理白背毛木耳的主要营养成分和功能氨基酸含量。【结果】与CK相比,添加1.0%、3.0%和5.0%豆粕处理的毛木耳菌丝洁白、吃料快、长势强劲,单袋产量分别增加3.54%、8.45%和12.21%,蛋白质含量分别提高11.65%、21.68%和23.71%,粗纤维含量分别提高47.30%、59.46%和13.51%,氨基酸总量分别提高10.77%、14.63%和25.24%,必需氨基酸含量分别提高16.42%、21.89%和29.35%。其中,添加5.0%豆粕处理的毛木耳菌丝长势浓密,单袋总产量显著高于其他处理(P<0.05),蛋白质含量、氨基酸总量、必需氨基酸和还原糖含量最高,粗纤维含量较低,粗脂肪含量最低。添加1.0%、3.0%和5.0%豆粕处理的单袋利润均高于CK,分别提高0.04、0.08和0.10元。【结论】白背毛木耳培养料添加豆粕,可明显提高其产量、主要营养成分及功能氨基酸含量,以添加5.0%豆粕的栽培效果最佳,可在白背毛木耳生产中推广应用。     

马尾松半同胞家系子代林遗传增益分析

以湖北省京山县太子山林场管理局马尾松实生种子园子代半同胞家系16年生林分为研究对象,测定了胸径、树高、枝下高、冠幅和材积等生长因子,结果表明:不同半同胞家系林木各生长因子间差异均达极显著水平,说明马尾松林木半同胞家系间存在较为丰富的遗传变异,具选育潜力。16年生半同胞家系马尾松林分树高、胸径及材积遗传力分别为0.843 5,0.740 5及0.750 6。根据性状遗传力的大小,以树高、胸径和材积作为优良马尾松半同胞家系选择指标。采用10%入选率进行选优时,可选出9个优良半同胞家系,其树高、胸径和材积遗传增益分别可达13.37%、25.57%和51.53%。     

Role of SIRT1/eNOS/NO signaling pathway in protective effect of ginsenoside Rb1 against replicative senescence of endothelial cells

AIM: To explore the effect of ginsenoside Rb1 on replicative senescence of endothelial cells and the role of SIRT1/eNOS/NO signaling pathway in this process. METHODS: The replicative senescence model of primary human umbilical vein endothelial cells (HUVECs) was established. The morphological change of the cells, the proportion of senescence-associated β-galactosidase (SA-β-Gal) positive cells and the plasminogen activator inhibitor 1 (PAI-1) expression were detected to assess the senescence model. The expression of eNOS and PAI-1 at mRNA and protein levels in the aging cells was determined by real-time PCR and Western blot before and after silencing of SIRT1 was performed. The NO concentration in the cell culture supernatant was measured by nitrate reductase assay. RESULTS: HUVECs with cumulative population-doubling level (CPDL) at 16 were chosen as the replicative senescence model in this research. Ginsenoside Rb1 at 80 μmol/L significantly reduced the expression of PAI-1 at mRNA and protein levels. Furthermore, ginsenoside Rb1 increased the expression of SIRT1 and eNOS at mRNA and protein levels, and increased the NO content. SIRT1 silencing inhibited the expression of eNOS at mRNA and protein levels and reduced NO generation, leading to an increase in the expression of PAI-1 at mRNA and protein levels. Upon intervention of ginsenoside Rb1, the eNOS and PAI-1 expression and the level of NO were not reversed. CONCLUSION: Ginsenoside Rb1 modulates SIRT1/eNOS/NO signaling pathway to prevent the replicative senescence of HUVECs.     

大棚黄瓜早熟栽培氮素肥料运筹试验

为解决黄瓜生产上盲目施肥现象,提高肥料利用率,降低农业投入品对环境的污染,以津春1号黄瓜为试材,采用测土配方施肥技术规范中的有机肥当量试验（X3）实施方案,研究了合肥市庐江县具有代表性的砂质壤土黄瓜种植的施肥模式。研究结果表明,黄瓜栽培中菜园地习惯性氮素养分的施入量不是最佳的施肥量;黄瓜生产中氮素养分施入的多少与产量不成正比;抗逆性好和产量最高的施肥处理是 N2P3K3＋M 组合,即每667 m2大田基施有机肥250 kg、尿素20 kg、普钙55 kg、硫酸钾21 kg,追施尿素8.5 kg、硫酸钾4.8 kg,产量为2871.67 kg。     

一株胶质芽胞杆菌YA-07的鉴定及固体发酵研究

胶质芽胞杆菌(Bacillus mucilaginosus)是一类能分解土壤中磷、钾和硅酸盐矿物的化能异养型好氧细菌,广泛应用于微生物肥料中。该菌在微生物肥料生产过程中主要是经液体发酵后由草炭吸附而成,这种工艺生产的微生物肥料有效活菌数和芽胞率均较低。因此,如何通过改善胶质芽胞杆菌的发酵方式和发酵条件以提高其有效活菌数和芽胞率显得尤为重要。对陕西省洛川县苹果园土壤中分离到的一株YA-07菌株通过形态学、生理生化实验和16s rDNA序列比对鉴定为胶质芽胞杆菌(Bacillus mucilaginosus)。通过单因素实验和正交试验,建立了一种使该菌产生高密度有效活菌数和高芽胞率的固体发酵条件。结果表明:YA-07能够产生大量有效活菌数和高芽胞率的培养基组分为500 mL培养瓶装草炭50 g,淀粉添加量3%,蛋白胨添加量3%,不添加无机盐和微量元素。在培养温度30℃,pH 7.0左右,接种量10%,培养时间144 h条件下,YA-07的有效活菌数可以达到1.58×10~9 cfu/g,芽胞率可以达到91.3%。利用固体发酵技术提高了胶质芽胞杆菌的有效活菌数和芽胞率,在改善微生物肥料产品质量的同时减少了环境的污染,对促进我国绿色农业的发展具有重要意义。