C/N ratio control and substrate addition for periphyton development jointly enhance freshwater prawn Macrobrachium rosenbergii production in ponds

The present research investigated the effect of carbon/nitrogen ratio (C/N ratio) control in ponds with or without substrate addition for periphyton development on production of giant freshwater prawn. C/N ratios of 10, 15 and 20 were investigated in 40 m^− 2 ponds stocked with 2 prawn juveniles (5.023 ± 0.02 g) m^− 2 with or without added substrates for periphyton development. The various treatment combinations of C/N ratio and periphyton substrate addition are abbreviated as ‘CN10’, ‘CN15’, ‘CN20’, ‘CN10 + P’, ‘CN15 + P’ and ‘CN20 + P’, P representing periphyton substrate. A locally formulated and prepared feed containing 30% crude protein with C/N ratio10 was applied. Tapioca starch was used as carbohydrate source for manipulating C/N ratio and applied to the water column separately from the feed. Increasing the C/N ratio from 10 to 20 reduced (P < 0.001) the total ammonia-nitrogen (TAN), nitrite–nitrogen (NO₂–N) and nitrate–nitrogen (NO₃–N) in water column and total Kjeldahl nitrogen (TKN) in sediment. The addition of substrates only influenced the NO₂–N concentration in the water column (P < 0.001). Increasing the C/N ratio raised the total heterotrophic bacterial (THB) population in the water column, sediment and periphyton (P < 0.001). It also increased the dry matter (DM), ash free dry matter (AFDM), and chlorophyll a content of periphyton (P < 0.001). The lowest specific growth rate (SGR), the highest food conversion ratio (FCR), and the lowest protein efficiency ratio (PER) were recorded in treatment CN10 (P < 0.05). The addition of substrates did not influence size at harvest (P > 0.05) but improved the survival from 62.8 to 72% (P < 0.001). Increasing the C/N ratio from 10 to 20 increased the net yield by 40% and addition of substrate increased the net yield by 23%. The combination of C/N ratio control and substrate addition increased the net yield by 75% from 309 (CN10) to 540 (CN20 + P) kg ha^− 1 (120 days)^− 1. This 75% higher production concurred with (1) a lower inorganic nitrogen content in the water column, (2) a higher THB abundance supplying additional single cell protein to augment the prawn production, and (3) an improved periphyton productivity and quality.     

Morphogenetic Effects of Different Mineral N-compounds on Roots of Maize (Zea mays L.), Spring Barley (Hordeum vulgare L.) and Broad Bean (Vicia faba L.)

Plants of maize ( Zea mays L.), spring barley ( Hordeum vulgare L.) and broad bean ( Vicia faba L.) were raised in tubes filled with a soil-sand mixture and supplied with nutrient solution. The nutrient supply was varied with regard to concentration and typ of compound of "N". Due to the relatively high concentrations of "N", dry matter of shoots and roots was reduced in comparison to the control; root morphology was affected in terms of root length and root thickness. The N-compounds, used in the experiment, exerted quantitatively different influences on dry matter production and root morphology, NH₄NO₃ being the N-form which had the weakest detrimental effects. There was no specific response to NH⁺₄ or NO⁻₃ but a strong influence could be shown for NH₄Cl and N_aNO₃. Probably not only the concentration of "N" and the form of "N" have a specific influence, but also the cations and anions associated with the N-containing ion are effective.     

鸡软骨细胞体外分离培养鉴定以及过表达miR-15a对软骨细胞的影响

为分析miR-15a在肉鸡不同组织中的表达情况,并探究过表达miR-15a对体外培养鸡软骨细胞的影响。本研究首先通过倒置显微镜观察、PCR、凝胶电泳和甲苯胺蓝染色对体外分离培养的软骨细胞进行鉴定。通过实时荧光定量PCR检测miR-15a在肢体内外翻畸形(valgus-varus deformity, VVD)组和健康组肉鸡中(各3只)各组织的表达量。之后通过CCK8和EDU方法分析软骨细胞过表达miR-15a后细胞增殖情况。软骨细胞转染miR-15a mimics后,通过qPCR检测软骨细胞的标志基因Collagen-2、Aggrecan、Collagen-10,成熟分化基因Runx2、Sox9、VEGF、MMP9,炎性因子IL-1β、IL-6、IL-8、IL-10、TNF-α、TGF-β3以及凋亡基因Fas、FasL、Bcl-2的表达量。并构建FKBP5 3'UTR的野生型载体和突变型载体,通过双荧光素酶检测报告检测miR-15a与FKBP5的靶向关系。结果表明,本研究所用的胰蛋白酶、Ⅱ型胶原酶和透明质酸酶联合消化法成功分离得到状态良好的软骨细胞。荧光定量结果显示,miR-15a在各组织中均有表达,与健康组相比,miR-15a在VVD组的肝(P < 0.01)、脾(P < 0.05)、胸腺(P < 0.01)中的表达量显著升高,在心和胸肌组织中的表达量显著降低(P < 0.01)。CCK8与EDU分析结果显示,与NC组相比,过表达miR-15a组软骨细胞增殖速度显著降低(P < 0.01),增殖细胞数量显著减少(P < 0.01)。qPCR结果显示,与mimics NC组相比,miR-15a mimics组的软骨细胞标志基因Aggrecan、成熟分化基因Sox9、Runx2表达量显著降低(P < 0.05),Fas基因表达量极显著上升(P < 0.01),FasL基因和抗凋亡基因Bcl-2极显著下降(P < 0.01)。成功构建了FKBP5 3'UTR野生型和突变型载体,双荧光素酶检测报告结果显示预测的靶基因FKBP5与miR-15a没有靶向关系。本研究成功分离并鉴定了鸡软骨细胞,过表达miR-15a抑制鸡软骨细胞增殖、成熟和分化并促进细胞凋亡。     

PK-15细胞的ISG15基因敲除促进PRV的复制

本试验旨在研究干扰素刺激基因15（interferon-stimulated gene 15,ISG15）敲除对猪伪狂犬病病毒（PRV）复制的影响。通过CRISPR/Cas9技术构建猪ISG15基因敲除猪肾上皮（PK-15）细胞系,利用CCK-8试剂盒检测PK-15敲除ISG15基因对细胞活力的影响,采用间接免疫荧光技术检测PK-15以及PK15-ISG15^-/-细胞感染PRV的增殖差异,通过RT-qPCR检测PRV-EP0、PRV-gE、PRV-VP16和IFN-β的转录水平,Western blot检测PRV-gE和ISG15的蛋白表达水平,以及通过病毒噬斑检测对子代病毒感染力的影响。结果表明,sgRNA1和sgRNA2均成功敲除ISG15基因;CCK-8试剂盒检测细胞活力结果表明,敲除ISG15基因对PK-15细胞活力无影响;间接免疫荧光检测结果表明,PRV感染后,PK15-ISG15^-/-细胞中的荧光强度明显高于PK-15细胞;RT-qPCR和Western blot结果表明,敲除ISG15可以促进PRV的转录和蛋白表达;病毒噬斑试验进一步显示,敲除ISG15可以促进PRV的复制。另外,RT-qPCR结果显示,敲除ISG15可以抑制PRV感染引起的IFN-β转录上调。本研究成功构建了PK15-ISG15^-/-细胞系,并通过PRV感染试验证实ISG15基因可以抑制PRV在PK-15细胞中的增殖,并推测这种抑制作用可能与IFN通路有关。     

不同N源对兴安落叶松苗木生长,养分吸收及离子平衡的影响(英文)

本文研究了不同N源对落叶松苗木干物重、养分吸收及离子平衡的影响。结果表明:施铵态N的苗木干物重小于对照处理;施硝铵态N的苗木生长与对照和施硝态N的苗木差别不大,但较施铵态N的苗木生长要好。铵态N与硝铵态N处理苗木地上部的阳离子总浓度受N水平的影响很小,而硝态N处理时则阳离子浓度增加;各处理对地上部阴离子浓度的影响均不大。在根部除硫酸根与钙离子外,阳离子与阴离子浓度均变化不大。硝态N处理的苗木具有较高的C-A值;△(C-A)/△Norg值在硝态N处理的苗木中随N供应量的增加而略有变化,但铵态N处理则明显下降;硝铵态N处理苗木的△(C-A)/△Norg值界于铵态N处理与硝态N处理之间。     

滴灌施肥条件下107杨幼林N、P、K养分吸收量与施肥量研究

杨树以其生长迅速、产量大、分布广、适应性强、易繁殖、易更新等特性,成为我国主要的速生造林树种,常作为短轮伐期工业用材来经营[1];同时,它在解决我国用材短缺和生态问题等方面也起着不可忽视的作用。在营造速生丰产林的过程中,施肥是一项关键措施,多项研究结果表明,施肥对杨树树高、胸径的生长具有促进作用,不同施肥处理对杨树生长的影响不同[2-8]。水和肥(主要是N     

香椿苗氮素营养的研究

试验结果表明，香椿苗对氮素敏感，合理施用氮肥促进苗木磷、氮元素吸收，生长期间叶片含磷量≥０．１４％，含氮量≥４．ｏ％．该试验地条件下，在施Ｐ２Ｏ５１３０ｋｇ·ｈｍ－２基础上，氮肥施用量与造林合格苗产量呈二次抛物线关系，回归方程为ｙ＝３０３１０．６＋５４６．８９ｘ－ｌ．０３９ｘ３，适宜施氮量范围为１８０～２７０ｋｇ·ｈｍ－２，最佳经济施氮量为２６１．３５ｋｇ·ｈｍ－２．试验还对施肥后的土壤养分变化情况进行了研究。     

赤枝栲干物质生产及氮磷营养动态研究

通过对1年生赤枝栲干物质的生产及氮磷营养动态研究,结果表明:不同的生长季节1年生赤枝栲苗木的各器官生长速率有很大差异,5~7月份根、叶生长迅速,以后迅速下降,8~10月份茎、侧根生长迅速;5~7月份大多数的光合产物用于形成根与叶,少量用于充实茎与侧根的生长;净同化率出现在5~7月份,与根系的生长呈显著的正相关;不同器官在其年生长周期中,氮、磷营养动态表现不同,养分吸收与赤枝栲生长发育规律相吻合。     

东北蕨类植物区系特征与分区

东北蕨类植物计２４科５１属１４０余种、变种，是中国北方蕨类多样性最丰富的地区。根据属的现代地理分布，东北蕨类植物可划分成７种地理成分，其中以北温带成分和东亚成分所占比例最大，反映了本区系的温带性质。区系中包含了东北亚蕨类植物区系的２个特有属，３０个特有种，是东北亚蕨类植物区系的中心区域。本区系与周围蕨类植物区系存在着广泛而复杂的联系：与朝鲜的共有种多达１０４种，与日本的共有种达１００种，与俄罗斯远东的共有种为８１种，与华北地区的共有种７２种，与秦岭地区的共有种７０种，与蒙古的共有种５３种，与西伯利亚的共有种４６种，与北美洲及欧洲的共有种各为３９种。根据蕨类植物的分布特点和种类组成，将东北蕨类植物区系划分成４个区，即长白、大兴安岭、蒙古、华北蕨类植物区。长白区有蔬类植物１２４种，东北亚特有成分主要分布于本区，是东北蕨类植物区系的中心区域；华北区有蕨类植物８７种，喜温喜热成分较多，反映了东北蕨类植物一定的热带、亚热带亲缘；大兴安岭区有蕨类植物４３种；蒙古区有蕨类植物近３０种，多耐寒、耐旱种类。东北蕨类植物的垂直分布带谱是很明显的，以长白山为例，海拔５００ｍ以下为落叶林蕨类植物带，海拔５００—１０００ｍ为暗针叶林     

离子注入对桉树萌发及苗期生长的影响

对6个尾叶桉和巨桉的全同胞和半同胞家系进行种子离子注入后,观察萌发和苗期生长,结果表明:(1)离子注入对种子发芽有刺激作用,既促进也抑制;(2)离子注入促进树高和侧根数生长,而抑制地径、叶长、叶宽和根生长,表明通过注入有可能获得生产中所需要的目的性状或品种;(3)离子注入的各家系平均生物量低于对照,但差异不显著;离子注入的家系平均叶比重、叶体积、叶肉体积和叶含水量均低于对照;(4)按突变临界值筛选,离子注入苗中共33株入选,突变率为5.323%;按各家系分别筛选,突变率在7.50%~30.00%.